Cell Mol Life Sci, 2000 Apr, 57(4), 542 - 51 Molecular mimicry: a critical look at exemplary instances in human diseases; Rose NR et al.; Molecular mimicry, the concept that antigenic determinants of microorganisms resemble antigenic determinants of the host, is frequently cited as a plausible mechanism to account for the association of infection and autoimmune disease . Based on analogous sequences of amino acids or on cross-reactions of monoclonal antibodies, numerous examples of such mimicry have been reported . There are, however, no clear examples of a human disease caused by molecular mimicry. Acta Obstet Gynecol Scand, 2000 Dec, 79(12), 1069 - 74 A case-referent study on fetal bacteremia and late fetal death of unknown etiology in Lithuania; Maleckiene L et al.; BACKGROUND: The objectives were to test the hypothesis that certain strains of microorganisms are present in fetal blood in a significant proportion of parturient women suffering unexplained third trimester fetal death, and to examine the correlation between fetal bacteremia and histologic chorioamnionitis and vasculitis . METHODS: A case-referent study was carried out on 58 pregnant women with fetal death of unknown etiology (cases) and 116 pregnant women at term (referents) with live fetuses . Cultures from maternal endocervix, amniotic fluid, placental homogenate, external ear and blood of newborns were performed in both groups . Histological examination of placentas and fetal membranes was carried out in order to identify chorioamnionitis and chorionic vasculitis . RESULTS: Intrauterine fetal bacteremia was observed in 36% of cases and in 0% of referents (p= 0.001) . Escherichia coli was the most common strain, isolated in 21% of fetal blood samples in cases . Extensive histologic chorioamnionitis was observed in 50% of cases with the presence of Escherichia coli in blood of stillborns . Chorionic vasculitis was found in 67% of such cases . Positive significant correlations between isolation of the Escherichia coli from maternal endocervix, amniotic fluid, placenta, fetal ear and blood in stillborns and histological chorioamnionitis and chorionic vasculitis were observed . CONCLUSIONS: Escherichia coli bacteremia was detected in a significant proportion of stillborns suffering a third trimester prelabor death . Fetal bacteremia significantly correlated with histologic signs of inflammation in placenta and membranes . Ascending subclinical intrauterine infection may play an important role in the etiology of otherwise unexplained late prelabor fetal death. J Biol Chem, 2001 Apr 6, 276(14), 11113 - 25 Epub 2000 Dec 14. Transepithelially transported pro-phenoloxidase in the cuticle of the silkworm, Bombyx mori . Identification of its methionyl residues oxidized to methionine sulfoxides; Asano T et al.; Pro-phenoloxidase (proPO) in insects is activated through the action of a protease cascade triggered by minute amounts of microbial cell wall components . It is an important molecule for the defense against invading microorganisms and for the repair of wounds . In the accompanying paper (Asano, T., and Ashida, M . (2001) J . Biol . Chem . 276, 11100-11112), a proPO isoform, proPO-HS, in the hemolymph of the silkworm, Bombyx mori, is reported to be transported to the cuticle . The transported proPO isoform was recovered from the cuticle and named proPO-CS . The elution profiles of proPO-CS and proPO-HS in reversed-phase high performance liquid chromatography (HPLC) were found to be different, giving a basis to the inference that proPO-CS is a modified form of proPO-HS . In the present study, we investigated the nature of the modifications occurring in proPO-CS, in which proteolytically and chemically cleaved fragments originating from the subunits of proPO-CS and proPO-HS were analyzed by reversed-phase HPLC, amino acid sequencing, and mass spectrometry . A subunit of the heterodimeric proPO-CS was found to contain five or six methionine sulfoxides, and another subunit was found to contain one methionine residue oxidized to the sulfoxide . All of the oxidized methionyl residues were identified . Other than oxidation of the methionyl residues, no additional modification of proPO-CS was found . In the model structure of each subunit of proPO-CS constructed by protein modeling with the known structures of the horseshoe crab, Limulus polyphemus, hemocyanin type II subunit as templates, the methionine residues identified as methionine sulfoxide had high degrees of accessibility to the solvent . The implication of the oxidation at the methionine residues is discussed in relation to the mechanism of transepithelial transport of proPO from the hemolymph to the cuticle. Postgrad Med J, 2001 Jan, 77(903), 16 - 9 The health professional's role in preventing nosocomial infections; Saloojee H et al.; Despite their best intentions, health professionals sometimes act as vectors of disease, disseminating new infections among their unsuspecting clients . Attention to simple preventive strategies may significantly reduce disease transmission rates . Frequent hand washing remains the single most important intervention in infection control . However, identifying mechanisms to ensure compliance by health professionals remains a perplexing problem . Gloves, gowns, and masks have a role in preventing infections, but are often used inappropriately, increasing service costs unnecessarily . While virulent microorganisms can be cultured from stethoscopes and white coats, their role in disease transmission remains undefined . There is greater consensus about sterile insertion techniques for intravascular catheters-a common source of infections-and their care . By following a few simple rules identified in this review, health professionals may prevent much unnecessary medical and financial distress to their patients. Cytometry, 2001 Jan 1, 43(1), 82 - 5 Quantitative assessment of phagocytic activity of hemocytes in the prawn, Penaeus merguiensis, by flow cytometric analysis; Lee YK et al.; BACKGROUND: The blood cells of crustaceans are involved in phagocytosis of invading microorganisms, contributing to their defense mechanisms . In this study, phagocytic activity of hemocytes of the prawn, Penaeus merguiensis, was quantitated by means of flow cytometric analysis . METHOD: This study was done in vitro . Hemolymph, which was extracted from prawns, was mixed with an equal volume of anticoagulant . Heat-killed Escherichia coli prestained with propidium iodide (PI) was then added . Hemocytes were fixed at various time intervals for flow cytometric analysis . This study was supplemented with electron micrographs using transmission electron microscopy (TEM), which showed three populations of hemocytes . RESULTS: It was observed that those hemocytes that were more active engulfed and digested bacteria readily, thus having higher red fluorescence intensity . The phagocytic activity was expressed as fluorescence unit or engulfed E . coli number per hemocyte . CONCLUSIONS: With this approach, the phagocytic and cellular activity of individual hemocyte populations could be studied quantitatively. Proc Natl Acad Sci U S A, 2001 Jan 2, 98(1), 60 - 2 An anthelmintic compound, nafuredin, shows selective inhibition of complex I in helminth mitochondria; Omura S et al.; Infections with parasitic helminths are important causes of morbidity and mortality worldwide . New drugs that are parasite specific and minimally toxic to the host are needed to counter these infections effectively . Here we report the finding of a previously unidentified compound, nafuredin, from Aspergillus niger . Nafuredin inhibits NADH-fumarate reductase (complexes I + II) activity, a unique anaerobic electron transport system in helminth mitochondria, at nM order . It competes for the quinone-binding site in complex I and shows high selective toxicity to the helminth enzyme . Moreover, nafuredin exerts anthelmintic activity against Haemonchus contortus in in vivo trials with sheep . Thus, our study indicates that mitochondrial complex I is a promising target for chemotherapy, and nafuredin is a potential lead compound as an anthelmintic isolated from microorganisms. FEMS Immunol Med Microbiol, 2000 Dec, 29(4), 323 - 8 Immune cell functions, lipids and host natural resistance; de Pablo MA et al.; Nutritional status may exert a profound effect on immune system functions . Hence, several parameters of immune system are modified by dietary lipid administration, as lymphocyte proliferation, cytokine production, natural killer activity, antigen presentation, etc . Thus, numerous studies have indicated the key role of lipids as immune response modulators . These properties have been applied in the treatment of autoimmune and inflammatory diseases . As a result, the reduction or suppression of immune status due to lipid incorporation promotes an impairment in the ability of host natural response to eliminate infectious microorganisms as bacteria or parasites . In the present review, we analyze the current status about the relationship among dietary lipids, reduction of immune parameters and reduction of host natural response against infectious diseases . Many discrepancies are discussed, although several studies indicate a close association between dietary lipid manipulation and impairment in the elimination of bacteria, viruses or parasites . On the other hand, other studies point out a beneficial effect of dietary lipid manipulation on the host natural response . Future investigations will determine the events involved in the regulation of immune response by fatty acids and their role in the elimination of pathogenic agents. Int J Gynaecol Obstet, 2000 Dec, 71 Suppl 1, S37 - 46 Sertaconazole: pharmacology of a gynecological antifungal agent; Palacin C et al.; Sertaconazole is a broad spectrum antifungal agent with excellent activity against yeasts, dermatophytes and opportunistic fungi . In addition to this antifungal efficacy, it has a good safety profile, sustained cutaneous retention, and low systemic absorption, all of which make it ideal for topical applications . In this study, the pharmacological properties of sertaconazole related to the treatment of vaginal fungi, in particular vulvovaginal candidiasis, are reviewed . As with all other infectious processes, the interacting components are infectious microorganism, host and drug . The following properties of sertaconazole have been investigated in pre-clinical studies: its in vitro spectrum of activity and potency against causative agents and accompanying factors in vaginal infection; its mechanism of action, whether it acts on the pathogenic properties of the microorganism; if it affects host defense mechanisms and how its antifungal activity is manifested in vivo in experimental candidiasis in the mouse. Biochem Biophys Res Commun, 2000 Dec 20, 279(2), 462 - 7 Amino acid residues conferring herbicide tolerance in tobacco acetolactate synthase; Chong CK et al.; Acetolactate synthase (ALS) is the common enzyme in the biosynthetic pathways leading to valine, leucine, and isoleucine in plants and microorganisms . ALS is the target site of several classes of structurally unrelated herbicides including sulfonylureas, imidazolinones, and triazolopyrimidines . To identify the residues conferring herbicide tolerance in tobacco ALS, site-directed mutagenesis for three residues, Ala121, Pro187 and Ser652, was performed . Mutant A121T showed strong resistance to Londax (a sulfonylurea) and Cadre (an imidazolinone), while mutant S652T was resistant only to Cadre . The S652N mutation abolished the binding affinity of FAD, and inactivated the enzyme . Double mutation of Ala121 and Ser652 with Thr yielded a mutant highly tolerant to Londax, Cadre, and TP (a triazolopyrimidine sulfonamide), but has enzymatic properties similar to those of wild-type . Substitution of Pro187 with Ser resulted in the enzyme highly susceptible to oxidation and fragmentation . These results suggest that two residues Ala121 and Ser652 are potent residues conferring herbicide resistance in tobacco ALS, and that double mutation of Ala121 and Ser652 by Thr can confer stronger tolerance to Londax, Cadre, and TP . Nature, 2000 Nov 30, 408(6812), 574 - 8 Geochemical evidence for terrestrial ecosystems 2.6 billion years ago; Watanabe Y et al.; Microorganisms have flourished in the oceans since at least 3.8 billion years (3.8 Gyr) ago, but it is not at present clear when they first colonized the land . Organic matter in some Au/U-rich conglomerates and ancient soils of 2.3-2.7 Gyr age has been suggested as remnants of terrestrial organisms . Some 2.7-Gyr-old stromatolites have also been suggested as structures created by terrestrial organisms . However, it has been disputed whether this organic matter is indigenous or exogenic, and whether these stromatolites formed in marine or fresh water . Consequently, the oldest undisputed remnants of terrestrial organisms are currently the 1.2-Gyr-old microfossils from Arizona, USA . Unusually carbonaceous ancient soils--palaeosols--have been found in the Mpumalanga Province (Eastern Transvaal) of South Africa . Here we report the occurrences, elemental ratios (C, H, N, P) and isotopic compositions of this organic matter and its host rocks . These data show that the organic matter very probably represents remnants of microbial mats that developed on the soil surface between 2.6 and 2.7 Gyr ago . This places the development of terrestrial biomass more than 1.4 billion years earlier than previously reported. Prikl Biokhim Mikrobiol, 2000 Nov-Dec, 36(6), 679 - 84 {Development of biological methods of combating steel corrosion, induced by aerobic microorganisms}; Rodin VB et al.; Cocultivation of degrading microorganisms and their antagonists decreases the corrosion loss of carbon steel by 20 to 80% . It was found that a microorganism can either accelerate or inhibit corrosion, depending on the nutrient . The magnitude of the effect on corrosion depends on the ability of the microorganism to respond to changes in the nutrient-medium composition by releasing acidic or alkaline metabolites. Prikl Biokhim Mikrobiol, 2000 Nov-Dec, 36(6), 672 - 8 {Microorganisms as possible indicators of soil pollution by dioxin-containing defoliants}; Mitsevich EV et al.; The diversity of microorganisms from soils treated in the past with various dosages of dioxin-containing defoliants was studied . Population alterations dependent on dioxin concentrations were elucidated . Soil fungi and, to a smaller extent, actinomycetes were found to be the most sensitive to dioxins. Prikl Biokhim Mikrobiol, 2000 Nov-Dec, 36(6), 661 - 5 {Development and testing of "Ekosorb" biosorbent based on association of petroleum-oxidizing bacteria for purifying petroleum-polluted soils}; Chugunov VA et al.; A biosorbent containing an association of oil-oxidizing bacteria as a main constituent was developed, in which Lessorb, a product of moss and wood thermal processing, was used as a carrier . Xeroprotectors preserving the cell viability and oil-oxidizing activity in the biosorbent on drying and after long-term storage were selected . The use of this biosorbent for cleaning oil-polluted sod-podzol soils showed a two-threefold cleanup rate acceleration at different pollution levels (8 and 24 l/m2), especially in the presence of a nitrogen-phosphate fertilizer . The biosorbent increased the populations of certain groups of soil microorganisms and the total soil biological activity. Prikl Biokhim Mikrobiol, 2000 Nov-Dec, 36(6), 642 - 6 {Microbial degraders of some organochlorine compounds}; Mitsevich EV et al.; A possibility of isolation of microorganisms, potential destructors of chlorinated organics from aged Vietnamese soils polluted with dioxine-containing defoliants was demonstrated . As an example, the ability of one isolated strain to metabolize pentachlorophenol and 2,4-dichlorophenoxyacetic acid was shown under laboratory conditions . An attempt was made to identify intermediates of pentachlorophenol metabolism using HPLC. Prikl Biokhim Mikrobiol, 2000 Nov-Dec, 36(6), 637 - 41 {Initial stages of steel biocorrosion}; Zhigletsova SK et al.; Initial stages of corrosion of mild steel induced by Klebsiela rhinoscleromatis BO2 were studied in various media . The effect of the microorganism was detected 8-10 h after inoculation . The number of viable cells were virtually unchanged within one month in all media, but the corrosive activity of the strain decreased . The corrosive activity of microorganisms can be determined by spectrophotometry even only after incubation for 24 h . At a low level of organic substrate, even strong colonization with microorganisms does not inevitably result in a significant damage to metals. Curr Microbiol, 2001 Jan, 42(1), 12 - 7 In vitro catabolism of histidine by mixed rumen bacteria and protozoa; Wadud S et al.; An in vitro study was conducted to examine the metabolism of histidine (His) by mixed rumen bacteria (B), mixed rumen protozoa (P), and a combination of the two (BP) . Rumen microorganisms were collected from fistulated goats fed with lucerne cubes (Medicago sativa) and a concentrate mixture twice a day . Microbial suspensions were anaerobically incubated with or without 2 mm each of His, or histamine (HTM), or 1 mm urocanic acid (URA) at 39 degrees C for 12 h . His and other related compounds in both supernatant and microbial hydrolysates were analyzed by HPLC . After 6- and 12-h incubations, the net degradation of His was 26.1% and 51.7% in B, 13.5% and 20.9% in P, and 21.7% and 46.0% in BP, respectively . The rate of the net degradation of His in B (98.0 micromol/g microbial nitrogen/h) was about 2.6 times higher than that of P during a 12-h incubation period . His was found to be degraded into urocanic acid (URA), imidazolelactic acid (ImLA), imidazoleacetic acid (ImAA), and histamine (HTM) . Of these degraded His was mainly converted into URA in all microbial suspensions . The production of ImLA and ImAA was higher in B than in P suspensions, whereas the production of HTM was higher in P than in B suspensions . From these results, the existence of diverse catabolic routes of His in rumen microorganisms was indicated. Vaccine, 2000 Nov 22, 19(7-8), 958 - 65 Immunogenicity of a foreign peptide expressed within a capsid protein of an attenuated coxsackievirus; Halim SS et al.; The immunogenicity of soluble peptides can be improved by expression within recombinant microorganisms . The immunogenicity of a peptide expressed within a capsid protein of an attenuated coxsackievirus B4 was evaluated . The insertion site was chosen based on its antigenic structure . A foreign peptide was inserted into a region of the VP1 capsid protein that was identified as a T helper cell epitope . A recombinant virus containing ten amino acids of ovalbumin sequence was genetically stable and retained the biological and physical characteristics of the parental virus . The recombinant was able to elicit a T helper cell response against ovalbumin sequences . This study shows, for the first time, that coxsackievirus can be used as an expression vector and that insertion of heterologous peptides into an immunogenic region is a viable strategy for inducing T helper cell responses against foreign sequences . The implications of this work are that the attenuated coxsackievirus variant may be useful as a vaccine vector for expressing T helper cell epitopes that are important in inducing protective immunity. Vaccine, 2000 Nov 22, 19(7-8), 862 - 76 A systematic approach to vaccine complexity using an automaton model of the cellular and humoral immune system . I . Viral characteristics and polarized responses; Kohler B et al.; A modern approach to vaccination faces the compound complexity of microorganism behavior and immune response triggering and regulation . Since computational modeling can yield useful guidelines for biological experimentation, we have used IMMSIM(3), a cellular automaton model for simulating humoral- and cell-mediated responses, to explore a wide range of virus-host relations . Sixty-four virtual viruses were generated by an assortment of speed of growth, infectivity level and lethal load . The outcome of the infections, as influenced by the immune response and the bolstering of cures, obtained by vaccine presensitization are illustrated in this first article . The results of the in machina experiments allow us to relate the success rate of responses to certain combinations of viral parameters and by freezing one or the other branch, and to determine that some viruses are more susceptible to humoral, and others to cellular responses, depending either on single parameters or combinations thereof . This finding allows prediction of which infection may be susceptible to polarized ((Th)(1)>Th(2) and Th(1)<Th(2)) responses and will eventually help designing vaccines whose action relies on antagonizing both the specificity and the behavior of the invader . A second, not lesser, result of this study is the finding that humoral and cellular responses, while cooperating, towards the cure of the infected body, also show significant patterns of competition and mutual thwarting. J Mol Biol, 2001 Jan 5, 305(1), 109 - 20 NMR structure of Streptomyces killer toxin-like protein, SKLP: further evidence for the wide distribution of single-domain betagamma-crystallin superfamily proteins; Ohki SY et al.; A protein isolated from the culture supernatant of the soil bacterium, Streptomyces sp . F-287, exhibits cytocidal effects for both budding and fission yeasts, and causes morphological changes of yeasts and filamentous fungi . This protein, which was the first killer toxin-like protein for yeasts identified in the Streptomyces microorganism, was named SKLP (Streptomyces killer toxin-like protein) . Since the amino acid sequence of the protein, as determined by sequential Edman degradations, seemed to be unique, we determined the structure by NMR spectroscopy . Although the actual target of SKLP in yeasts has not been determined yet, the structure might give us a clue to characterize the targets . The solution structure of SKLP determined by NMR, however, turned out to be a single-domain crystallin-like protein, with two Greek key motifs and a short extra beta-strand at the N terminus . The final ensemble of 20 NMR structures overlaid onto their mean coordinate with rmsd values of 0.32(+/-0.06) A for the backbone atoms involved in the secondary structure elements . As a yeast killer toxin, WmKT, isolated from the yeast strain Williopsis mrakii also has a Greek key beta-barrel fold, we have made a detailed comparison of the structural features of SKLP with the other crystallin superfamily proteins . It is very interesting that SKLP has a unique electrostatic potential distribution on the molecular surface . Namely, one surface of the beta-barrel fold in SKLP has a large negatively charged region, with an isolated positive charge of the Arg62 side-chain at the center . The edge of this surface is surrounded by positively charged residues, including Arg31, Arg65 and Arg74 . The salient features of the charge distribution on this surface and the cluster of Arg residues might be related to the target binding of SKLP . Rapid Commun Mass Spectrom, 2000, 14(24), 2362 - 6 Identification of an N-(hydroxysulfonyl)oxy metabolite using in vitro microorganism screening, high-resolution and tandem electrospray ionization mass spectrometry; Pilard S et al.; Preliminary metabolic profiling of a drug under pre-clinical development revealed the presence of a minor unknown metabolite with a positive ion electrospray ionization (ESI) mass spectrum identical to that of the unchanged compound . Since the low concentration of the compound did not allow any additional experiments, preparative bioconversion using fungi was used to obtain a substantial amount of the molecule . Negative ion ESI-MS and tandem mass spectrometry (MS/MS) in combination with accurate mass measurements obtained on a quadrupole/time-of-flight instrument (Q-TOF) led to the positive identification of a hydroxylamide sulfoconjugated metabolite . Biochim Biophys Acta, 2000 Dec 15, 1524(2-3), 189 - 95 Demonstration of the central dark line in crystals of dental calculus; Kakei M et al.; Using an electron microscope and Fourier transform infrared (FTIR) microspectroscopy, we studied the lattice images of crystallites of dental calculus to demonstrate the presence of the central dark line (CDL) in its crystallite and to compare this CDL with that of bone and synthetic hydroxyapatite crystals . Ultrastructural observations revealed clearly a number of crystallites, which displayed a proper lattice image and CDL similar to that of bone, in the dental calculus . FTIR microspectroscopy revealed that the dental calculus displayed a set of major spectra analogous to that of bone . These results suggest that the formation process of hydroxyapatite crystals with CDL in dental calculus, which is considered to be an unusual type of calcified structure in association with microorganisms, is basically similar to that of the ordinary calcifying hard tissues (bone, enamel, etc.). FEMS Microbiol Lett, 2000 Dec 15, 193(2), 237 - 41 Enzymatic versus spontaneous S-methyl thioester synthesis in Geotrichum candidum; Helinck S et al.; The synthesis of short chain S-methyl thioesters was investigated in Geotrichum candidum strain GcG . The results indicated the involvement of an enzymatic reaction in this microorganism that led to the synthesis of S-methyl thioacetate (MTA) when methanethiol and acetyl-CoA were used as substrates . MTA was generated from these substrates by enzymatic or spontaneous reactions, whose relative importance depended largely on pH and temperature . For longer chain acyl-CoA compounds (C3 to C6), thioester synthesis was primarily spontaneous . Short chain fatty acid activation by a CoA residue probably is a prerequisite for the synthesis of S-methyl thioesters. Radiology, 2000 Dec, 217(3), 647 - 56 Pulmonary infections in immunocompromised hosts: the importance of correlating the conventional radiologic appearance with the clinical setting; Oh YW et al.; The lung is one of the most frequently involved organs in a variety of complications in the immunocompromised host . Among the pulmonary complications that occur in this kind of patient, infection is the most common and is associated with high morbidity and mortality . Although chest radiography and computed tomography (CT) are essential diagnostic tools, radiologists often have difficulty in establishing the correct diagnosis on the basis of radiologic findings alone . The reasons are that the immunocompromised host is potentially susceptible to infection from many different microorganisms and that radiologic findings are seldom specific for the detection of a particular pathogen . Experience has shown that a particular clinical setting predisposes patients to infection by particular pathogens . The setting comprises (a) the specific epidemiologic or environmental exposure, (b) the type of underlying immune defect, (c) the duration and severity of immune compromise, and (d) the progression rate and pattern of the radiologic abnormality . Correlating the radiologic appearance with the clinical setting can expedite diagnosis and appropriate therapy . In this review, the authors describe the clinical settings that are helpful in choosing the radiologic approach to treatment of the immunocompromised host who presents with suspected pulmonary infection. Int Microbiol, 2000 Mar, 3(1), 9 - 16 Molecular phylogeny: pitfalls and progress; Moreira D et al.; Molecular phylogeny based on nucleotide or amino acid sequence comparison has become a widespread tool for general taxonomy and evolutionary analyses . It seems the only means to establish a natural classification of microorganisms, since their phenotypic traits are not always consistent with genealogy . After an optimistic period during which comprehensive microbial evolutionary pictures appeared, the discovery of several pitfalls affecting molecular phylogenetic reconstruction challenged the general validity of this approach . In addition to biological factors, such as horizontal gene transfer, some methodological problems may produce misleading phylogenies . They are essentially (i) loss of phylogenetic signal by the accumulation of overlapping mutations, (ii) incongruity between the real evolutionary process and the assumed models of sequence evolution, and (iii) differences of evolutionary rates among species or among positions within a sequence . Here, we discuss these problems and some strategies proposed to overcome their effects. Int Microbiol, 1999 Dec, 2(4), 207 - 16 Not plants or animals: a brief history of the origin of Kingdoms Protozoa, Protista and Protoctista; Scamardella JM; In the wake of Darwin's evolutionary ideas, mid-nineteenth century naturalists realized the shortcomings of the long established two-kingdom system of organismal classification . Placement in a natural scheme of Protozoa, Protophyta, Phytozoa and Bacteria, microorganisms that exhibited plant-like and animal-like characteristics but obviously differed in organization from larger plants and animals, challenged traditional classification . The attempts of naturalists to classify these organisms outside the constraints of the plant and animal kingdoms led to concepts of additional kingdoms (Protozoa, Protista, Protoctista, etc.) to accommodate the nature of these organisms as not true plants or animals. Int Microbiol, 1999 Sep, 2(3), 145 - 54 Intracellular parasitism and molecular determinants of Legionella virulence; Belyi Y; Bacteria of the genus Legionella are intracellular parasites and major human pathogens . They bind to surface receptors, penetrate eukaryotic cells and initiate complex disorders during phagocytosis . These disorders include inhibition of oxidative burst, a decrease in phagosome acidification, the blocking of phagosome maturation and changes in organelle trafficking . As a result, the microorganisms prevent the bactericidal activity of the phagocyte and transform the phagosome into a niche for their replication . Biological, biochemical and molecular-genetic approaches have been used to identify a panel of bacterial products that may be involved in Legionella virulence . They include cytotoxins, several enzymes and a set of genes thought to encode proteins of the export machinery . However, despite distinct progress in research, the molecular mechanisms underlying intracellular parasitism in Legionella are unclear. Int Microbiol, 1998 Dec, 1(4), 295 - 300 Selection of very small differences in bacterial evolution; Baquero F et al.; As the Science of Biology is constantly changing due to new discoveries and advanced techniques it is essential that a systematic study of the environmental causes of natural selection on microorganisms be conducted . Very small phenotypic differences among individuals within bacterial populations arise as a result of spontaneous genetic variation, but the evolutionary importance of these small changes is frequently considered to be non-significant . Recent in vitro experiments indicate that efficient selection of these very small differences may take place in environmental compartments where a particular intensity of the selective agent is exerted . Model studies based on competition between bacterial populations only differing in one or two amino acid changes of a detoxifying antibiotic enzyme (e.g . beta-lactamase) have shown that at a narrow range of antibiotic concentrations the variant population is strongly selected over the original type, despite the extremely low phenotypic differences in antibiotic susceptibility . These selective concentrations are expected to occur in precise environmental compartments (selective compartments) . Due to the high frequency of structured habitats in natural environments, the intensity of selective agents is commonly exerted along certain gradients . Each one of the points forming these gradients (or intersection among gradients) may have a particular selective ability for a specific genetic variant . Considering the environment as a composition of an extremely high number of specific selective compartments may help to understand the existence of high levels of genetic variability in natural bacterial populations . This may be one of the clues towards the unraveling of bacterial evolution. Int Microbiol, 1998 Dec, 1(4), 285 - 94 Crucial crises in biology: life in the deep biosphere; Guerrero R; The origin and evolution of life on Earth are the result of a series of crises that have taken place on the planet over about 4500 millions of years since it originated . Biopoiesis (origin of life), ecopoiesis (origin of ecosystems) and the first ecosystems (stromatolites and microbial mats), as well as eukaryopoiesis (origin of nucleated cells) are revised . The paper then focuses on the study of the deep biosphere, describing ecosystems never found before, which are independent of solar radiation and have changed previous assumptions about the requirements of life; even the concept of biosphere, as Vernadsky defined it, has increased its scope . Since the discovery, in 1987, of bacteria growing in the crevices of rocks at 500 m deep, in boreholes drilled near the Savanna River, Aiken, South Carolina, other bacteria have been found in the deep subsurface reaching depths of about 3 km (e.g., in the Columbia River Basalt Group, near Richland, Washington state), in an anaerobic, hot, high-pressure environment . Some kinds of microorganisms can thrive at such depths, living in many cases a geochemical existence, by using very specialized metabolisms, which depend on the local environments . The existence of organisms independent from photosynthetic production is the most outstanding, novel feature of the deep biosphere . Living beings might not need other energy and chemical sources than those which occur in the development of all planetary bodies . Life, therefore, could even be an ineluctable outcome of planetary evolution and, as a corollary, a natural continuation of the usual development of physical phenomena in the universe. J, Exp . Mar . Biol . Ecol. . 2000 Dec 20, 255(2), 201 - 214 Diurnal changes in pore water sulfide concentrations in the seagrass Thalassia testudinum beds: the effects of seagrasses on sulfide dynamics; Lee K et al.; The dynamics of the seagrass-sulfide interaction were examined in relation to diel changes in sediment pore water sulfide concentrations in Thalassia testudinum beds and adjacent bare areas in Corpus Christi Bay and lower Laguna Madre, Texas, USA, during July 1996 . Pore water sulfide concentrations in seagrass beds were significantly higher than in adjacent bare areas and showed strong diurnal variations; levels significantly decreased during mid-day at shallow sediment depths (0-10 cm) containing high below-ground tissue biomass and surface area . In contrast, diurnal variations in sediment sulfide concentrations were absent in adjacent bare patches, and at deeper (>10 cm) sediment depths characterized by low below-ground plant biomass or when the grasses were experimentally shaded . These observations suggest that the mid-day depressions in sulfide levels are linked to the transport of photosynthetically produced oxygen to seagrass below-ground tissues that fuels sediment sulfide oxidation . Lower sulfide concentrations in bare areas are likely a result of low sulfate reduction rates due to low organic matter available for remineralization . Further, high reoxidation rates due to rapid exchange between anoxic pore water and oxic overlying water are probably stimulated in bare areas by higher current velocity on the sediment surface than in seagrass beds . The dynamics of pore water sulfides in seagrass beds suggest no toxic sulfide intrusion into below-ground tissues during photosynthetic periods and demonstrate that the sediment chemical environment is considerably modified by seagrasses . The reduced sediment sulfide levels in seagrass beds during photosynthetic periods will enhance seagrass production through reduced sulfide toxicity to seagrasses and sediment microorganisms related to the nutrient cycling. J Vet Diagn Invest, 2000 Nov, 12(6), 552 - 7 Pathogenesis of liver lesions caused by experimental infection with Piscirickettsia salmonis in juvenile Atlantic salmon, Salmo salar L; Almendras FE et al.; Piscirickettsia salmonis, the etiologic agent of salmonid rickettsial septicemia (SRS), or piscirickettsiosis, causes substantial economic losses to the salmon industry . The pathogenesis of the disease has not been fully characterized . The aim of this study is to describe the hepatic lesions associated with experimental P . salmonis infection in Atlantic salmon juveniles . Fish were maintained in fresh water and inoculated intraperitoneally (IP), orally, or on the gill surface with P . salmonis . A group of uninfected fish was kept as control . Liver samples from 5 fish in each inoculated group and 3 controls were collected weekly and processed for histological and immunohistochemical examination . Thickening of the liver capsule by inflammatory cells was a characteristic histologic feature of IP inoculated fish . Three weeks post-IP inoculation, 8 fish had died and 2 fish were sampled . Histological changes at this time consisted of vasculitis, presence of fibrin thrombi, vacuolated hepatocytes and focal areas of necrosis . Leukocytes containing intracytoplasmic basophilic microorganisms were seen within hepatic sinusoids . Vasculitis and intracytoplasmic vacuoles were prominent features in fish inoculated orally and on the gill surface . The presence of P . salmonis within hepatocellular vacuoles, endothelial cells, and leucocytes was confirmed by immunohistochemistry . The intracellular location of P . salmonis and the vascular damage seen in infected fish are characteristic of rickettsial infections . Histological lesions induced by experimental infection with P . salmonis using the oral and gill surface routes were similar to those observed in natural outbreaks of piscirickettsiosis . The tropism of P . salmonis for endothelial cells explains the vascular lesions observed in SRS, whereas hepatic lesions are due to ischemic necrosis and direct injury by intracytoplasmic organisms. Angiology, 2000 Oct, 51(10), 827 - 30 Identificaiton of chlamydia penumoniae DNA in caroitd plaques; Chierichetti F et al.; Chlamydia pneumoniae (CP) is a bacterium that in recent years has been investigated as an etiologic agent for atherosclerosis . It is a ubiquitous microorganism that has been isolated in various regions of the vascular system and its prevalence is about 10% in the patient population . This study involved a group of 43 patients (27 men, 16 women, mean age 68 years) who underwent carotid endarterectomy . About 9.3% of the patients yielded plaques that tested positive for the DNA genome of Chlamydia pneumoniae. Med Dosw Mikrobiol, 2000, 52(2), 165 - 71 {Bactericidal properties of neutrophils from peripheral blood (PMN)of patients with Lyme borreliosis}; Izycka A et al.; In recent years in Poland, the interest has increased in studies about tick borne diseases, mainly Lyme borreliosis . Immune response and genotype of pathogen play an important role in the course of this disease . Phagocytic cells, especially PMN are dominant in defence mechanisms against bacterial infections . The main feature of PMN is their ability to destroy pathogenic microorganisms by phagocytosis . The aim of this study was to estimate the phagocytic activity of PMN connected with intracellular respiratory burst in patients with Lyme borreliosis . The PMN activity tests completed were: phagocytosis, spontaneous and reduced of nitrotetralizate blue test (NBT) . Decreased phagocytic activity and oxygen metabolism of PMN from patients with borreliosis in comparison with values of controls were found . Normalization of these parameters after treatment was observed . Changed phagocytic activity connected with intracellular oxygen metabolism during the course of therapy was the main observation . Depression of phagocytic activity of PMN connected with oxygen metabolism can influence defence reactions in patients with Lyme borreliosis . It is suggested that changes observed are acquired and associated with Borrelia burgdorferi presence. Biochim Biophys Acta, 2000 Nov 20, 1460(2-3), 276 - 90 An elementary kinetic model of energy coupling in biological membranes; Cristina E et al.; The purpose of this work is to contribute to the understanding of the fundamental kinetic properties of the processes of energy coupling in biological membranes . For this, we consider a model of a microorganism that, in its plasma membrane, expresses two electrogenic enzymes (E(1) and E(2)) transporting the same monovalent cation C and electrodiffusive paths for C and for a monovalent anion A . E(1) (E(2)) couples transport C to the reaction S(1)<-->P(1) (S(2)<-->P(2)) . We developed a mathematical model that describes the rate of change of the electrical potential difference across the membrane, of the internal concentrations of C and A, and of the concentrations of S(2) and P(2) . The enzymes are incorporated via two-state kinetic models; the passive ionic fluxes are represented by classical formulations of electrodiffusion . The microorganism volume is maintained constant by accessory regulatory devices . The model is utilized for stationary and dynamic studies for the case of bacteria employing the electrochemical gradient of Na(+) as energetic intermediate . Among other conclusions, the results show that the membrane potential represents the relevant kinetic intermediate for the overall coupling between the energy donor reaction S(1)<-->P(1) and the synthesis of S(2). Proc Natl Acad Sci U S A, 2000 Dec 19, 97(26), 14590 - 5 Cell injury releases endogenous adjuvants that stimulate cytotoxic T cell responses; Shi Y et al.; General immunostimulants (adjuvants) are essential for generating immunity to many antigens . In bacterial infections, adjuvants are provided by components of the microorganism, e.g., lipopolysaccharide . However, it is unclear what provides the adjuvant effect for immune responses that are generated to tumors and many viruses . Here we show that cell injury and death of tumor or even normal cells provide a potent adjuvant effect for the stimulation of cytotoxic T lymphocyte responses . This adjuvant activity is constitutively present in the cytoplasm of cells and is increased in the cytoplasm of cells dying by apoptosis . The release of these components stimulates immune responses both locally and at a distance, and provides a simple mechanism to alert the immune system to potential danger in almost all pathological situations. Curr Opin Biotechnol, 2000 Dec, 11(6), 565 - 71 Dynamic resolution and stereoinversion of secondary alcohols by chemo-enzymatic processes; Azerad R et al.; To overcome the maximum 50% yield limitation of classical resolution methods, deracemization processes involving a racemization step (dynamic resolution) or a prochiral intermediate (stereoinversion) have been developed . The use of transition metal complexes as racemizing agents, in combination with an enzymatic reaction, has been successfully extended to the deracemization of a number of simple or functionalized sec-alcohols . A two-enzyme process has been also investigated for their sequential or simultaneous deracemization . Other prominent results arise from an (apparently general) oxidoreduction process catalyzed by a single whole-cell microorganism. Genetics, 2000 Dec, 156(4), 1949 - 58 Sequence variation at two eosinophil-associated ribonuclease loci in humans; Zhang J et al.; Host defense against invading pathogens is of great importance to the survival of higher organisms . We have been studying the evolution of mammalian eosinophil-associated ribonucleases (EARs), which are members of the ribonuclease A superfamily with known antipathogen activities . Earlier studies showed that positive selection promoted rapid diversification of paralogous EAR genes in both primates and rodents . Intraspecifically, however, it is unknown whether these genes also have divergent alleles . The recent discovery that the gene repertoire of the EAR family is much larger in rodents than in primates has led us to consider the possibility that primates maintain a large number of polymorphic alleles to compensate for a smaller gene repertoire . Here we present sequences of 2417 nucleotides at the two EAR loci, the eosinophil-derived neurotoxin (EDN, RNase 2) and eosinophil cationic protein (ECP, RNase 3), from >50 human individuals . Our data demonstrate that the nucleotide diversities (0.06-0.11%) at these loci are typical for human nuclear genes, thus permitting us to reject this polymorphism hypothesis . No significant departure from neutrality is noted and no signs of overdominant selection are observed . Similar patterns were observed in a preliminary study of chimpanzees . In summary, our results suggest that the antipathogen functions of the primate EARs are conserved after they are established and that these proteins are not currently undergoing rapid diversification in response to challenge from invading microorganisms. Braz J Infect Dis, 1998 Dec, 2(6), 285 - 290 Morphofunctional Study of Blood Polymorphonuclear Leucocytes in HIV-Seropositive Individuals; Spada C et al.; The impairment of leukocytic functions in AIDS infected individuals, where opportunistic infections are manifested, has been under study since 1985 . However, controversy remains concerning leukocyte function during initial stages of HIV infection . In the context of the precarious immunologic and phagocytic defense of persons with AIDS, and the resulting difficulty they have to control microorganism invasion and opportunistic infections, examination of the host defense functions played by leukocytes in seropositive HIV persons is particularly important . To that end, our study sought to assess, during the initial stage of HIV infection, the laboratory parameters associated myeloid cells which are known to be altered during disease stage . Seventy-five (75) persons seropositive to HIV-1 (by the ELISA test, confirmed by immunofluorescence), and twenty-six (26) controls were tested . These individuals were screened by infectologists and their disease severity classified according to the Walter Reed Army Institute System . We observed that myeloperoxidase enzyme activity, superoxide anion production, and fungicidal action in homologous serum were all diminished in patients classified as WR-1, and progressively decreased in WR-2-4 . The percent phagocytizing neutrophils and the number of C . albicans phagocytized were normal in WR-1 patients, but diminished in WR-2-4 . We conclude that neutrophil function is diminished in HIV-infected persons at the beginning of infection, and that the defects increase as the HIV disease progresses. J Clin Microbiol, 2000 Dec, 38(12), 4408 - 11 Detection of Chlamydia pneumoniae and Helicobacter pylori DNA in human atherosclerotic plaques by PCR; Farsak B et al.; Chlamydia pneumoniae and Helicobacter pylori can cause persistent infections of the respiratory and gastrointestinal tract, respectively . It has been suggested that persistent infection of arteries with these bacteria can contribute to the development of atherosclerosis . The aims of this study were to determine the presence of C . pneumoniae and H . pylori DNA in atherosclerotic plaque samples by PCR and to evaluate the correlation between clinical status and DNA positivity of these bacteria . Eighty-five consecutive patients (mean age, 59 +/- 10; 75 male, 10 female) undergoing coronary artery bypass grafting, carotid endarterectomy, and surgery of the abdominal aorta for atherosclerotic obstructive lesions were included in the study . Forty-six endarterectomy specimens from the atherosclerotic lesions and 39 specimens from healthy regions of the ascending aorta, which were accepted as the control group, were excised . The presence of microorganism DNA in endarterectomy specimens was assessed by PCR . C . pneumoniae DNA was found in 12 (26%) of 46 endarterectomy specimens and none of the healthy vascular-wall specimens (P < 0.001), while H . pylori DNA was found in 17 (37%) of 46 endarterectomy specimens and none of the controls (P < 0.001) . Either C . pneumoniae or H . pylori DNA was positive in 23 (50%) of 46 patients and none of the controls (P < 0 . 001) . Six of the atherosclerotic lesions showed coexistence of both of the microorganism DNAs . The presence of C . pneumoniae and H . pylori DNA in a considerable number of atherosclerotic plaques but their absence in healthy vascular wall supports the idea that they may have a role in the development of atherosclerosis, especially in countries where infection is prevalent and where conventional risk factors fail to explain the high prevalence of atherosclerotic vascular disease. Semin Cancer Biol, 2000 Oct, 10(5), 331 - 40 Requirement for reverse immune surveillance for the growth of germinal center-derived murine lymphomas; Ponzio NM et al.; The concept of reverse immune surveillance, first conceived over 12 years ago, described the relationship that existed between germinal center-derived B cell lymphoma cells and the host immune system in SjL/J mice . According to reverse immune surveillance, recognition of tumor cell antigens and a response by the host immune system is required for tumor growth . The phenomenon of reverse immune surveillance related to B cell lymphomas has recently also been characterized in another inbred mouse strain, C57L/J . Moreover, elements of reverse immune surveillance have been observed in several other mouse strains that develop B cell lymphomas, suggesting that this lymphomagenic mechanism may be more common than first envisioned . In SJL and C57L mice, the B lymphoma cells express an MMTV-encoded superantigen (vSAg29) that stimulates syngeneic CD4+ T cells bearing Vbeta16 in their TCR . In contrast to the mRNAs for other MMTVs in normal mouse B cells, vSAg29 mRNA initiates in the env (META) region, undergoes splicing in the 3' env region, and continues through the 3' LTR . Copious cytokine production, including IFN-gamma, IL-4 and IL-5 accompanies the response of the T cells to this vSAg . In addition to cytokines produced by vSAg-responsive T cells, more recent evidence indicates that another cytokine, LTalphabeta2, which is expressed on the lymphoma cell surface, also plays a role in the promotion of the B cell lymphoma growth . It is possible that interaction with LTbeta-R on follicular dendritic cells or other stromal elements facilitates tumor growth by preventing apoptosis of the malignant B cells . To what degree these findings in the mouse are relevant to the development and/or growth of human B lymphoma cells remains to be determined . However, endogenous retroviral sequences do exist in the human genome . Interestingly, some of these sequences are homologous to MMTV, and are transcribed in B lymphoblastoid cells . Moreover microorganisms that are infectious for human B cells, such as EBV and Herpes Virus 8, may also produce superantigens. Med Trop (Mars), 2000, 60(2), 171 - 8 {Dangerous sharks in tropical seas}; Maslin J et al.; Sightseeing travel in tropical zones is a growing industry . The risks incurred by travelers depend on the destination, duration of stay, individual behavior, and type of leisure activity . Water sports expose visitors to encounters with dangerous marine animals . Shark attacks are rare but always serious occurrences . Divers should handle any shark, regardless of size, with due precaution . Prevention of shark attack depends on avoiding encounters by not attracting the attention of the shark and knowing the proper attitude to adopt in case an encounter should occur . Active and passive protection can be used, but each method has advantages and disadvantages depending on the situation . Rescue operations are difficult due to the gravity of injuries and their occurrence in a marine environment . This along with the nature of the aggressor explain that many attacks are immediately fatal . Wounds are often deep with involvement of bone, blood vessels, and nerves . A possible source of complication in survivors is infection, which can involve uncommon microorganisms associated with bacteria in sharks mouth or marine environment. Nat Med, 2000 Dec, 6(12), 1348 - 54 Efficient presentation of exogenous antigen by liver endothelial cells to CD8+ T cells results in antigen-specific T-cell tolerance; Limmer A et al.; Myeloid antigen-presenting cells (APC) are known to cross-present exogenous antigen on major histocompatibility class I molecules to CD8+ T cells and thereby induce protective immunity against infecting microorganisms . Here we report that liver sinusoidal endothelial cells (LSEC) are organ-resident, non-myeloid APC capable of cross-presenting soluble exogenous antigen to CD8+ T cells . Though LSEC employ similar molecular mechanisms for cross-presentation as dendritic cells, the outcome of cross-presentation by LSEC is CD8+ T cell tolerance rather than immunity . As uptake of circulating antigens into LSEC occurs efficiently in vivo, it is likely that cross-presentation by LSEC contributes to CD8+ T cell tolerance observed in situations where soluble antigen is present in the circulation. Microbes Infect, 2000 Oct, 2(12), 1523 - 35 Use of fluorescent probes to assess physiological functions of bacteria at single-cell level; Joux F et al.; A wide diversity of fluorescent probes is currently available to assess the physiological state of microorganisms . The recent development of techniques such as solid-phase cytometry, the increasing sensitivity of fluorescence tools and multiparametric approaches combining taxonomic and physiological probes have improved the effectiveness of direct methods in environmental and industrial microbiology. Neth J Med, 2000 Dec, 57(6), 215 - 23 Totally implantable venous access devices: evaluation of complications and a prospective comparative study of two different port systems; Hartkamp A et al.; BACKGROUND: Totally implantable venous access devices (TIVADs) are valuable instruments in case prolonged intravenous therapy is required, but implantation and use of these devices are associated with complications . The purpose of this study was to evaluate perioperative and long-term complications associated with TIVADs . In addition, we compared two different types of TIVADs with respect to implantation, care protocol and patients' comfort . METHODS: In a retrospective study perioperative and long-term complications in a general oncology population were analysed . In a prospective randomized study comparison of two types of TIVADs was carried out . RESULTS: Perioperative complications occurred in 27 (21.4%) of 126 implanted TIVADs: catheter malposition (16.7%) in 21 patients, pneumothorax (0.8%) in one and haemorrhage (4.0%) in five . Long-term complications appeared in 31 (25.2%) out of 123 TIVADs: thrombosis in 9 (7.3%), especially associated with malposition of the tip of the catheter; infection in 10 (8.1%); extravasation in 2 (1.6%); migration of the catheter tip in 6 (4.8%); pain at reservoir in 3 (2.4%) and inaccessibility of the port in 1 (0.8%) . No significant differences were found with respect to implantation, care accessibility and patients' comfort between the two TIVADs . CONCLUSIONS: The use of TIVADs is associated with some risk of serious perioperative and long-term complications . In case of thrombotic complications these systems can be saved with appropriate treatment . Correct positioning of the catheter tip is essential to prevent thrombotic complications . In case of TIVAD-related infectious complications, the possibility of saving the TIVAD depends on the causative microorganism and type of infection . Furthermore, to increase patients' satisfaction with TIVADs they should be well informed about the surgical procedure and possible disadvantages of these devices. Scand J Gastroenterol, 2000 Oct, 35(10), 1033 - 40 Different patterns of Helicobacter pylori adherence to gastric mucosa cells in children and adults . An ultrastructural study; Blom J et al.; BACKGROUND: Infection with Helicobacter pylori in childhood may be the initiation of a lifelong coexistence between microorganisms and epithelial cells resulting in chronic inflammation . The adhesion pattern of H . pylori found in antral biopsies from a group of H . pylori-infected children with recurrent abdominal pain was compared with a group of H . pylori-infected adults suffering from dyspepsia, in an attempt to reveal differences in the type of adhesion . METHODS: The histology of antrum biopsies and the ultrastructure of adherent H . pylori in biopsies from 26 children (median age, 10.1 years) were compared with organisms in biopsies from 19 adults (median age, 54.4 years) . RESULTS: More than 1000 adherent H . pylori were studied and divided into four types of adhesion: 1) contact to microvilli; 2) connection to the plasma membrane via filamentous material; 3) adhesive pedestal formation; and 4) abutting or making a depression in the plasma membrane . Contact to microvilli was significantly higher (69% versus 39%; P = 0.002) in children compared with adults and comprised two-thirds of all adherent organisms in children . The more intimate adhesion types as abutting or adhesive pedestals dominated in adults . CONCLUSIONS: These results indicate a change in contact types between H . pylori and gastric epithelial cells in adults compared with children and this may be a natural development in the lifelong infection of humans. Crit Rev Biochem Mol Biol, 2000, 35(5), 317 - 37 The production of pyrethrins by plant cell and tissue cultures of Chrysanthemum cinerariaefolium and Tagetes species; Hitmi A et al.; Pyrethrins, the most economically important natural insecticide, comprise a group of six closely related monoterpene esters . The industrial production is based on their extraction from Chrysanthemum cinerariaefolium (Pyrethrum) capitula . The world production of natural pyrethrins still falls short of global market demand stimulating the research in in vitro production as an alternative to conventional cultivation methods . The different biotechnological alternatives such as callus cultures, shoot and root cultures, plant cell suspension cultures, and bioconversion of precursors by means of enzymatic synthesis or genetically engineered microorganisms, as well as the progress achieved in methods for the identification and quantitation of insecticidal compounds have been reviewed . Although technology for plant cell culture exists, industrial applications have, to date, been limited due to both the low economical viability and technological feasibility at large scale . Bioconversion of readily available precursors looks more attractive, but more research is needed before this technology is used for the industrial production of pyrethrins. FEMS Microbiol Ecol, 2000 Sep 1, 33(3), 191 - 196 Spatial distribution of protists in the presence of macroaggregates in a marine system; Artolozaga I I et al.; The spatial distribution of marine protistan communities in the presence of organic macroaggregates, formed from natural seawater, was studied in several microcosm experiments . The presence of macroaggregates had two main effects . First, the size of the communities of bacteria, flagellates and ciliates increased, as these communities were three orders of magnitude higher in the aggregates than in the microcosm water . In addition, it brought the diversification on the niches accessible to planktonic microorganisms, as three phases were formed: water, aggregates and aggregate-water interphase . Some of the detected protistan taxa were only found in the water, and therefore they can be considered as truly free-swimming protists . Others quickly colonised the aggregates, and finally, some of them showed a preference for the aggregate-water interphase . We discuss this spatial structuring of the protistan community on the basis of their feeding strategies and structural and behavioural characteristics. Biofizika, 2000 Sep-Oct, 45(5), 882 - 7 {Mathematical model of microorganism biomass growth in the absence of a limiting substrate and inhibiting agents}; Shelykh IA et al.; A mathematical model for the growth of microbial cells upon submerged cultivation was constructed . The model describes the growth phases of the biomass of microorganisms in the absence of inhibiting agents and limitation by substrate in the medium . At the basis of model is the requirement that cells should not be in physical contact during some time in order that they can divide . The model involves the known concepts of statistical physics . The consequences of the model are discussed. Br J Anaesth, 2000 Nov, 85(5), 735 - 9 Gram staining of protected pulmonary specimens in the early diagnosis of ventilator-associated pneumonia; Mimoz O et al.; We evaluated prospectively the use of Gram staining of protected pulmonary specimens to allow the early diagnosis of ventilator-associated pneumonia (VAP), compared with the use of 60 bronchoscopic protected specimen brushes (PSB) and 126 blinded plugged telescopic catheters (PTC) obtained from 134 patients . Gram stains were from Cytospin slides; they were studied for the presence of microorganisms in 10 and 50 fields by two independent observers and classified according to their Gram stain morphology . Quantitative cultures were performed after serial dilution and plating on appropriate culture medium . A final diagnosis of VAP, based on a culture of > or = 10(3) c.f.u . ml-1, was established after 81 (44%) samplings . When 10 fields were analysed, a strong relationship was found between the presence of bacteria on Gram staining and the final diagnosis of VAP (for PSB and PTC respectively: sensitivity 74 and 81%, specificity 94 and 100%, positive predictive value 91 and 100%, negative predictive value 82 and 88%) . The correlation was less when we compared the morphology of microorganisms observed on Gram staining with those of bacteria obtained from quantitative cultures (for PSB and PTC respectively: sensitivity 54 and 69%, specificity 86 and 89%, positive predictive value 72 and 78%, negative predictive value 74 and 84%) . Increasing the number of fields read to 50 was associated with a slight decrease in specificity and positive predictive value of Gram staining, but with a small increase in its sensitivity and negative predictive value . The results obtained by the two observers were similar to each other for both numbers of fields analysed . Gram staining of protected pulmonary specimens performed on 10 fields predicted the presence of VAP and partially identified (using Gram stain morphology) the microorganisms growing at significant concentrations, and could help in the early choice of the treatment of VAP . Increasing the number of fields read or having the Gram stain analysed by two independent individuals did not improve the results. Annu Rev Genet, 2000, 34, 139 - 164 Assessment of bacterial pathogenesis by analysis of gene expression in the host; Mahan MJ et al.; A number of techniques have been developed to assess the expression of microbial virulence genes within the host (in vivo) . These studies have shown that bacteria employ a wide variety of mechanisms to coordinately regulate the expression of these genes during infection . Two tenets have emerged from these studies: bacterial adaptation responses are critical to growth within the host, and interactions between microorganisms and the microenvironments of their hosts cannot be revealed from in vitro studies alone . Results that support these tenets include (i) the prevalent class of in vivo expressed genes are involved in adaptation to environmental stresses, (ii) pathogens recovered from host tissues (versus laboratory growth) are often more resistant to host killing mechanisms, and (iii) virulence gene expression can differ in the animal compared to laboratory media . Thus, pathogenicity comprises the unique ability to adapt to the varied host milieus encountered as the infection proceeds. DNA Seq, 2000, 11(3-4), 183 - 92 A BAC library and paired-PCR approach to mapping and completing the genome sequence of Sulfolobus solfataricus P2; She Q et al.; The original strategy used in the Sulfolobus solfataricus genome project was to sequence non overlapping, or minimally overlapping, cosmid or lambda inserts without constructing a physical map . However, after only about two thirds of the genome sequence was completed, this approach became counter-productive because there was a high sequence bias in the cosmid and lambda libraries . Therefore, a new approach was devised for linking the sequenced regions which may be generally applicable . BAC libraries were constructed and terminal sequences of the clones were determined and used for both end mapping and PCR screening . The PCR approaches included a novel chromosome walking method termed "paired-PCR" . 21 gaps were filled by BAC end sequence analyses and 6 gaps were filled by PCR including three large ones by paired-PCR . The complete map revealed that 0.9 Mb remained to be sequenced and 34 BAC clones were selected for walking over small gaps and preparing template libraries for larger ones . It is concluded that an optimal strategy for sequencing microorganism genomes involves construction of a high-resolution physical map by BAC end analyses, PCR screening and paired-PCR chromosome walking after about half the genome sequence has been accumulated. Adv Biochem Eng Biotechnol, 2000, 70, 35 - 40 Antibiotica research in Jena from penicillin and nourseothricin to interferon; Bocker H et al.; Milestones of antibiotics research and biotechnology in Jena/Thuringia are: 1938--Hans Knoll established a strain collection of microorganisms; 1942--production of penicillin on laboratory scale by Hans Knoll; since 1945--development of industrial production processes for penicillin and streptomycin; 1952--production of BCG-vaccine; since 1956--development of biotechnical processes in the Institute of Microbiology and Experimental Therapy for actinomycin C, oxytetracyclin, erythromycin, paromomycin, turimycin, griseofulvin, nystatin, and nourseothricin, and in the 1980s for streptokinase, staphylokinase, and interferons . After the German unification the Hans-Knoll-Institute for Natural Products Research was founded. Am Surg, 2000 Nov, 66(11), 1004 - 10 Zinc, copper, and metallothionein metabolism after jejunoileal bypass surgery or small bowel resection in rats; Rodriguez JA et al.; Liver dysfunction is a frequent complication of jejunoileal bypass (JIB) surgery, a procedure commonly used until recently to treat morbid obesity . It has been suggested that liver failure in JIB patients is due to bacterial overgrowth and translocation from the bypassed intestine . Because invading microorganisms cause hepatic inflammation these experiments evaluated zinc, copper, and metallothionein (MT) in two experimental rat models of intestinal surgery to determine whether their distribution in plasma and tissues was similar to the highly characteristic pattern observed during an inflammatory response . In the JIB rat model 90 per cent of the small intestine was isolated from the flow of digesta but remained viable in the abdominal cavity . In the small bowel resection (SBR) model 90 per cent of the small intestine was removed and the remaining intestine was resected . Data collected 21 days after surgery showed decreased growth rate and plasma zinc in the SBR and JIB rats that was significantly improved by supplemental zinc . All other measures of zinc, copper, and MT metabolism in the SBR rats were similar to those of controls . In JIB rats, however, liver copper, MT protein, and MT mRNA were significantly elevated, and a high proportion of the intracellular zinc and copper was associated with MT . The pattern of zinc, copper, and MT distribution in systemic circulation and liver of JIB rats suggests hepatic inflammation superimposed on low zinc and copper status . Lack of a similar response in the SBR rats confirms the involvement of the bypassed intestinal segment and supports the hypothesis that bacterial overgrowth and translocation are responsible for liver inflammation and dysfunction in JIB patients. Z Gastroenterol, 2000 Oct, 38(10), 855 - 72 {The mechanisms of antigen uptake in the small and large intestines: the roll of the M cells for the initiation of immune responses}; Gebert A et al.; The gut-associated lymphoid tissues, e.g., the Peyer's patches and the appendix, constantly internalize antigenic material to rapidly generate an immune response, if necessary . This sampling of antigens is performed by specialized epithelial cells, the "membranous" or "microfold" (M) cells of the dome epithelia . M cells possess a unique ultrastructure and are typically in contact with lymphoid cells . They endocytose macromolecules and particles, including entire microorganisms, at their apical membrane, transport these in vesicles to their basolateral membrane, and exocytose them to the intercellular space . This article reviews the structural and functional characteristics of M cells in the digestive tract in humans and other species . Specializations of M cells for antigen uptake and transport comprise the composition of their apical membrane, a modified cytoskeleton as compared to enterocytes, and a large pocket-like invagination of the basolateral membrane populated by lymphocytes . Besides ultrastructural characteristics, histochemical markers are listed that are available for detecting M cells . The origin and differentiation pathways of M cells and enterocytes of the dome epithelium are outlined and critically commented on . Because M cells are known entry sites of various pathogens and, in the future, might be employed for the oral application of drugs and vaccines, the clinical relevance of M cells in health and disease is discussed. Mol Biochem Parasitol, 2000 Nov, 111(1), 95 - 105 Identification of six Trypanosoma cruzi lineages by sequence-characterised amplified region markers; Brisse S et al.; Six discrete phylogenetic lineages were recently identified in Trypanosoma cruzi, on the basis of multilocus enzyme electrophoresis and random amplified polymorphic DNA (RAPD) characterisation . The objective of the present study was to develop specific PCR-based markers for the identification of each of the six lineages . Eighty-seven T . cruzi stocks representative of all the lineages were characterised by RAPD with three primers, resulting in the identification of three fragments that were specifically amplified in the given sets of lineages . After cloning and sequencing these fragments, three pairs of sequence-characterised amplified region (SCAR) primers were designed . After PCR amplification using the SCAR primers, the initial polymorphism was retained either as the presence or absence of amplification, or as size variation between the PCR products . Although most PCR products, taken individually, were distributed across several lineages, the combination of the three SCAR markers resulted in characteristic patterns that were distinct in the six lineages . Furthermore, T . cruzi lineages were distinguished from Trypanosoma rangeli, T . cruzi marinkellei and T . cruzi-like organisms . The excellent correspondence of these new PCR markers with the phylogenetic lineages, allied with their sensitivity, makes them reliable tools for lineage identification and strain characterisation in T . cruzi . The approach described here could be generalised to any species of microorganism harbouring clear-cut phylogenetic subdivisions. J Infect Dis, 2001 Jan 1, 183(1), 119 - 24 Epub 2000 Nov 16. Biological selection of variant-specific surface proteins in Giardia lamblia; Singer SM et al.; Immune evasion is frequently cited as the main reason for antigenic variation in pathogenic microorganisms . To better understand the role of switching of variant-specific surface proteins (VSPs) in Giardia lamblia-host interactions, antigenic variation during infections of mice and gerbils was examined, using clones that predominantly expressed unique VSPs . As expected, VSPs were selected against during infections of immunocompetent hosts . In contrast, in immunodeficient hosts, some VSPs were selected for and others were selected against . These diverse patterns of selection demonstrate that there are host-VSP interactions that exert both positive and negative selective pressures on parasites, independent of the adaptive immune response . Furthermore, selection was dependent on both the particular VSP and the host . Thus, the large number of VSP genes in G . lamblia may allow the parasite to infect multiple different hosts, and antigenic variation could be a mechanism to expand the parasite's host range. J Biochem Biophys Methods, 2000 Nov 20, 46(1-2), 1 - 9 A microcalorimetric method for studying the biological effects of La(3+) on Escherichia coli; Ruming Z et al.; A microcalorimetric technique based on the bacterial heat-output was explored to evaluate the stimulatory effect of La(3+) on Escherichia coli . The power-time curves of the growth metabolism of E . coli and the effect of La(3+) on it were studied using an LKB-2277 BioActivity Monitor, stopped-flow method, at 37 degrees C . For evaluation of the results, the maximum power (P(max)), the growth rate constants (k) and the heat effects (Q(LOG), Q(STAT)) for the log phase, the stationary phase and the total heat effect (Q(T)) for E . coli were determined . The microcalorimetric method agreed with the conventional methods, such as cell numbers and biomass . La(3+) in the concentration ranges of 0-400 microg/ml has stimulatory effects on E . coli, while La(3+) ion of higher concentrations (>400 microg/ml) can inhibit the growth . This phenomenon is very similar to those observed from the in vitro cells and tissues from animals, plants and some microorganisms by other methods. Bioessays, 2000 Dec, 22(12), 1067 - 74 Adaptive mutation: implications for evolution; Foster PL; Adaptive mutation is defined as a process that, during nonlethal selections, produces mutations that relieve the selective pressure whether or not other, nonselected mutations are also produced . Examples of adaptive mutation or related phenomena have been reported in bacteria and yeast but not yet outside of microorganisms . A decade of research on adaptive mutation has revealed mechanisms that may increase mutation rates under adverse conditions . This article focuses on mechanisms that produce adaptive mutations in one strain of Escherichia coli, FC40 . These mechanisms include recombination-induced DNA replication, the placement of genes on a conjugal plasmid, and a transient mutator state . The implications of these various phenomena for adaptive evolution in microorganisms are discussed. J Endourol, 2000 Oct, 14(8), 689 - 92 Transurethral microwave thermotherapy for the treatment of prostatitis; Liatsikos EN et al.; The lethal action of microwaves on various microorganisms is well established and has been exploited in various clinical settings . Transurethral microwave thermotherapy (TUMT) has become a recognized modality for the treatment of prostatic diseases . Recently, it has been applied for the treatment of patients with nonbacterial prostatitis unresponsive to traditional therapeutic schemes . We review the current literature and present our recent encouraging experience with the in vitro bactericidal effect of microwaves on bacteria considered possible etiologic agents of prostatitis . Thus, we may consider the application of TUMT in patients with chronic bacterial prostatitis. J Mol Biol, 2000 Nov 24, 304(2), 219 - 29 High precision NMR structure of YhhP, a novel Escherichia coli protein implicated in cell division; Katoh E et al.; YhhP, a small protein of 81 amino acid residues encoded by the yhhP gene in the Escherichia coli database, is implicated in cell division although the precise biological function of this protein has not been yet identified . A variety of microorganisms have similar proteins, all of which contain a common CPxP sequence motif in the N-terminal region . We have determined the three-dimensional solution structure of YhhP by NMR spectroscopy in order to obtain insight into its biological function . It folds into a two-layered alpha/beta-sandwich structure with a betaalphabetaalphabetabeta fold, comprising a mixed four-stranded beta-sheet stacked against two alpha-helices, both of which are nearly parallel to the strands of the beta-sheet . The CPxP motif plays a significant structural role in stabilizing the first helix as a part of the new type N-capping box where the Cys-Pro peptide bond adopts a cis configuration . The structure of YhhP displays a striking resemblance to the C-terminal ribosome-binding domain of translation initiation factor IF3 (IF3C) . In addition, the surface charge distribution of the RNA-recognition helix of IF3C is nearly the same as that of the corresponding helix of YhhP . These results suggest a structure-based hypothesis in which binding to an RNA target plays an essential role in the function of this ubiquitous protein . Microb Ecol, 2000 Aug, 40(3), 260 - 272 "BACWAVE," a Spatial-Temporal Model for Traveling Waves of Bacterial Populations in Response to a Moving Carbon Source in Soil; Zelenev VV et al.; Previously, we discovered the phenomenon of wavelike spatial distributions of bacterial populations and total organic carbon (TOC) along wheat roots . We hypothesized that the principal mechanism underlying this phenomenon is a cycle of growth, death, autolysis, and regrowth of bacteria in response to a moving substrate source (root tip) . The aims of this research were (i) to create a simulation model describing wavelike patterns of microbial populations in the rhizosphere, and (ii) to investigate by simulation the conditions leading to these patterns . After transformation of observed spatial data to presumed temporal data based on root growth rates, a simulation model was constructed with the Runge-Kutta integration method to simulate the dynamics of colony-forming bacterial biomass, with growth and death rates depending on substrate content so that the rate curves crossed over at a substrate concentration within the range of substrate availability in the model . This model was named "BACWAVE," standing for "bacterial waves." Cyclic dynamics of bacteria were generated by the model that were translated into traveling spatial waves along a moving nutrient source . Parameter values were estimated from calculated initial substrate concentrations and observed microbial distributions along wheat roots by an iterative optimization method . The kinetic parameter estimates fell in the range of values reported in the literature . Calculated microbial biomass values produced spatial fluctuations similar to those obtained for experimental biomass data derived from colony forming units . Concentrations of readily utilizable substrate calculated from biomass dynamics did not mimic measured concentrations of TOC, which consist not only of substrate but also various polymers and humic acids . In conclusion, a moving pulse of nutrients resulting in cycles of growth and death of microorganisms can indeed explain the observed phenomenon of moving microbial waves along roots . This is the first report of wavelike dynamics of microorganisms in soil along a root resulting from the interaction of a single organism group with its substrate. Microb Ecol, 2000 Aug, 40(3), 250 - 259 Wavelike Distributions of Microbial Populations along an Artificial Root Moving through Soil; van Bruggen AH et al.; In a previous paper, we described wavelike distributions of bacterial populations along roots of wheat, and hypothesized that one mechanism underlying these distributions might be growth and death cycles of microorganisms in response to a moving nutrient source, the root tip . Similar wavelike distributions in microbial biomass were obtained using a simulation model for growth and death of bacteria in relation to their substrate (BACWAVE) . The model was parameterized with data from one experiment on rhizosphere bacterial populations along wheat roots, and compared against a similar but independent experiment . In experiments described in this paper, similar wavelike distributions in bacterial populations were observed in response to a single artificial exudate moving linearly through a soil that had been air-dry for almost 2 years . The period of the spatial waves was longer when the tip of the artificial exudate moved at a speed of 4.2 cm/day compared to a tip moving at 1.1 cm/day, but after transformation into the temporal domain, the periods of the waves were similar for both moving speeds . The observed distributions were simulated using the BACWAVE model with similar parameter values as derived from the experiment with wheat roots mentioned above . The results presented in this paper confirm our hypothesis that wavelike distributions of bacterial population along plant roots can arise from "exudates" released primarily from the root tip, without the need for additional exudation points. Proc Natl Acad Sci U S A, 2000 Nov 21, 97(24), 13092 - 6 Measuring the forces involved in polyvalent adhesion of uropathogenic Escherichia coli to mannose-presenting surfaces; Liang MN et al.; Mechanisms of bacterial pathogenesis have become an increasingly important subject as pathogens have become increasingly resistant to current antibiotics . The adhesion of microorganisms to the surface of host tissue is often a first step in pathogenesis and is a plausible target for new antiinfective agents . Examination of bacterial adhesion has been difficult both because it is polyvalent and because bacterial adhesins often recognize more than one type of cell-surface molecule . This paper describes an experimental procedure that measures the forces of adhesion resulting from the interaction of uropathogenic Escherichia coli to molecularly well defined models of cellular surfaces . This procedure uses self-assembled monolayers (SAMs) to model the surface of epithelial cells and optical tweezers to manipulate the bacteria . Optical tweezers orient the bacteria relative to the surface and, thus, limit the number of points of attachment (that is, the valency of attachment) . Using this combination, it was possible to quantify the force required to break a single interaction between pilus and mannose groups linked to the SAM . These results demonstrate the deconvolution and characterization of complicated events in microbial adhesion in terms of specific molecular interactions . They also suggest that the combination of optical tweezers and appropriately functionalized SAMs is a uniquely synergistic system with which to study polyvalent adhesion of bacteria to biologically relevant surfaces and with which to screen for inhibitors of this adhesion. Tsitologiia, 2000, 42(9), 891 - 5 {The effect of media tonicity on Escherichia coli resistance to heating with different gradient}; Morozov II et al.; The influence of NaCl water solutions and glycerine hypertonic concentration on the survival of bacteria Escherichia coli B/r heated with different values of heat drop was investigated . It was shown that the transfer of cell suspensions from isotonic conditions to media with raised osmotic pressure, preliminarily heated up to 60 degrees C, and the following heating at this temperature inhibited differences in cell sensitivity to heating at different heat drop . Unlike, it was found that the transfer of cell suspensions from isotonic conditions to hypertonic media before and after heating at 60 degrees C increased differences in resistance of these microorganisms to heating at different heat drop . It is proposed that different resistance of bacteria to damaging action of hyperthermia at different heat drop, and a modified influence of hypertonic solutions on these differences may be due to heat induced destabilization of cell osmotic homeostasis . The extent of expression of this destabilization may be determined by a quantitative ratio of osmotic pressure values in the cell-suspension medium system in particular temperature and tonic environmental conditions. Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 2000 Nov, 90(5), 647 - 50 Bacterial leakage in coronally unsealed root canals obturated with 3 different techniques; Siqueira JF Jr et al.; OBJECTIVE: The purpose of this in vitro study was to evaluate the coronal leakage of microorganisms from saliva into root canals filled by 3 obturation techniques . STUDY DESIGN: Obturated canals were mounted in an apparatus and then exposed to human saliva . The number of days required for the entire contamination of the root canal was recorded . Evaluation was carried out for 60 days . RESULTS: Regardless of the technique used, a significant number of specimens were contaminated after 30 and 60 days . No significant differences were detected among the techniques (P >.05) . CONCLUSIONS: Results indicated that none of the techniques tested could predictably produce a coronal bacteria-tight seal of the root canal after direct saliva challenge. FEMS Microbiol Rev, 2000 Dec, 24(5), 591 - 9 Microbial interactions involving sulfur bacteria: implications for the ecology and evolution of bacterial communities; Overmann J et al.; A major goal of microbial ecology is the identification and characterization of those microorganisms which govern transformations in natural ecosystems . This review summarizes our present knowledge of microbial interactions in the natural sulfur cycle . Central to the discussion is the recent progress made in understanding the co-occurrence in natural ecosystems of sulfur bacteria with contrasting nutritional requirements and of the spatially very close associations of bacteria, the so-called phototrophic consortia (e.g . 'Chlorochromatium aggregatum' or 'Pelochromatium roseum') . In a similar way, microbial interactions may also be significant during microbial transformations other than the sulfur cycle in natural ecosystems, and could also explain the low culturability of bacteria from natural samples. FEMS Microbiol Rev, 2000 Dec, 24(5), 555 - 65 Ribosomal RNA-targeted nucleic acid probes for studies in microbial ecology; Amann R et al.; With readily applicable hybridization assays, mainly based on rRNA-targeted nucleic acid probes, and direct, cultivation-independent sequence retrieval, microbiologists can for the first time determine the true composition of microbial communities . Phylogenetic identification and exact spatiotemporal quantification of microorganisms will in the future become prerequisites for high quality studies in microbial ecology just as good taxonomy and solid quantification have always been for macroecology . This review is intended to give a short history of the development of rRNA-targeted nucleic acid probes and probe technologies, as well as of their application in microbial ecology . The current state of the art is described, and we will try to look into the future . Over the last decade, rRNA-targeted probes have become a handy tool for microbial ecologists . In order to speed up the transformation of microbial ecology from a mostly descriptive to a hypothesis-driven, experimental science more intense use must be made of the taxonomic precision and quantitativeness of rRNA-targeted probes. Biol Chem, 2000 Sep-Oct, 381(9-10), 965 - 72 Macromolecular intelligence in microorganisms; Bruggeman FJ et al.; Biochemistry and molecular biology have been focusing on the structural, catalytic, and regulatory properties of individual macromolecules from the perspective of clarifying the mechanisms of metabolism and gene expression . Complete genomes of 'primitive' living organisms seem to be substantially larger than necessary for metabolism and gene expression alone . This is in line with the findings of silent phenotypes for supposedly important genes, apparent redundancy of functions, and variegated networks of signal transduction and transcription factors . Here we propose that evolutionary optimization has been much more intensive than to lead to the bare minima necessary for autonomous life . Much more complex organisms prevail . Much of this complexity arises in the nonlinear interactions between cellular macromolecules and in subtle differences between paralogs (isoenzymes) . The complexity can only be understood when analyzed quantitatively, for which quantitative experimentation is needed in living systems that are as simple and manipulatable as possible, yet complex in the above sense . We illustrate this for the glutamine synthetase cascade in Escherichia coli . By reviewing recent molecular findings, we show that this cascade is much more complex than necessary for simple regulation of ammonia assimilation . Simulations suggest that the function of this complexity may lie in quasi-intelligent behavior, including conditioning and learning. Biol Chem, 2000 Sep-Oct, 381(9-10), 911 - 20 Metabolic networks: a signal-oriented approach to cellular models; Lengeler JW; Complete genomes, far advanced proteomes, and even 'metabolomes' are available for at least a few organisms, e.g., Escherichia coli . Systematic functional analyses of such complete data sets will produce a wealth of information and promise an understanding of the dynamics of complex biological networks and perhaps even of entire living organisms . Such complete and holistic descriptions of biological systems, however, will increasingly require a quantitative analysis and the help of mathematical models for simulating whole systems . In particular, new procedures are required that allow a meaningful reduction of the information derived from complex systems that will consequently be used in the modeling process . In this review the biological elements of such a modeling procedure will be described . In a first step, complex living systems must be structured into well-defined and clearly delimited functional units, the elements of which have a common physiological goal, belong to a single genetic unit, and respond to the signals of a signal transduction system that senses changes in physiological states of the organism . These functional units occur at each level of complexity and more complex units originate by grouping several lower level elements into a single, more complex unit . To each complexity level corresponds a global regulator that is epistatic over lower level regulators . After its structuring into modules (functional units), a biological system is converted in a second step into mathematical submodels that by progressive combination can also be assembled into more aggregated model structures . Such a simplification of a cell (an organism) reduces its complexity to a level amenable to present modeling capacities . The universal biochemistry, however, promises a set of rules valid for modeling biological systems, from unicellular microorganisms and cells, to multicellular organisms and to populations. J Clin Periodontol, 2000 Nov, 27(11), 846 - 53 Bacterial susceptibility to amoxicillin and potassium clavulanate in advanced periodontitis patients not responding to mechanical therapy; Kleinfelder JW et al.; BACKGROUND, AIMS: Between 4 and 8% of periodontitis patients are reported to respond poorly to conventional therapy . In these cases, adjunctive use of systemic antibiotics might be a reasonable therapeutic approach . The purpose of this study was to evaluate the effects of systemic amoxicillin/clavulanate as adjunct to periodontal surgery on the predominant subgingival microorganisms in patients not responding to mechanical therapy . Furthermore, the bacterial susceptibility to amoxicillin/clavulanate was analyzed before and after therapy in order to assess the clinical validity of pre-therapeutic susceptibility testing . METHODS: In 10 periodontitis subjects with no subgingival detection of Actinobacillus actinomycetemcomitans, the predominant subgingival organisms were identified using the identification system Rapid ID 32 A as well as antibiotic susceptibility was tested utilizing the E test . RESULTS: Porphyromonas gingivalis and Prevotella oralis were detected in 7/10 subjects and could no more recovered after therapy . Fusobacterium nucleatum and Peptostreptococcus micros were present in 5/10 patients before treatment, but could be detected in 6/10, resp . 3/10 after therapy . In 4/10 subjects harboring F . nucleatum and in 3/10 with P . micros, those organisms were not targeted by amoxicillin/clavulanate, although post-treatment testing revealed their alleged susceptibility (MICs varied from 0.023 to 0.032 microg/ml, resp . from 0.125 to 2.0 microg/ ml) . CONCLUSIONS: The results of this study suggest that the outcomes of conventional methods of susceptibility testing have to be interpreted very carefully when being used for treatment of plaque-related diseases . Furthermore, since the endpoint of systemic antibiotic treatment as adjunct to conventional therapy is elimination of F . nucleatum or P . micros in patients harboring these organisms, the use of amoxicillin/clavulanate appears not to be justified. J Environ Sci Health B, 2000 Nov, 35(6), 677 - 87 Atrazine degradation in a containerized rhizosphere system; Costa RM et al.; The effect of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) on rhizosphere microorganisms and its fate in a containerized rhizosphere system was studied . The rhizosphere system consisted of corn grown in pot containing a defined potting mix of sand and bark with atrazine . Sterilized potting mix and a container without plants served as controls . Atrazine was extracted and analyzed via HPLC . Fluorescent pseudomonad populations increased 100-fold in the rhizposphere during a 60-day incubation period as compared to the nonvegetated control . Atrazine degradation was higher in the rhizosphere system (half-life of 7 days) compared to the nonvegetated control (half-life of greater than 45 days) . The major degradation product detected in the rhizosphere system was deisopropylatrazine; other products detected included deethylatrazine, deethylhydroxyatrazine, deisopropylatrazine and hydroxyatrazine . Hydroxyatrazine was detected in the nonvegetated and sterile controls . The containerized rhizosphere system provides an experimental system to study the fate of pesticidal chemicals as well as the effects on microbial populations. Rev Soc Bras Med Trop, 2000 Sep-Oct, 33(5), 417 - 25 {Epidemiology and ecology of dermatophytoses in the City of Fortaleza: Trichophyton tonsurans as important emerging pathogen of Tinea capitis}; Brilhante RS et al.; Dermatophytosis is the most common skin infectious disturbance in the world . In this research 2,297 patients were evaluated with suspected clinical lesions of dermatophytosis . It was observed that, 534 (23.2%) patients tested positive for dermatophytes . T . rubrum was the most prevalent specie (49.6%; p < or = 0.05), followed by T . tonsurans (34.4%), M . canis (7%) and T . mentagrophytes (6.2%) . When the species isolated was correlated with the respective anatomical localization, it was observed that T . tonsurans was the most frequent isolated in scalp lesions (73.9%; p < or = 0.01) . On the other hand, T . rubrum was the main specie involved in body lesions (72.8%; p < or = 0.05) . Therefore, in scalp infections it was observed that, there was an absolute prevalence of T . tonsurans . This evidence is different from the statistical data collected in the southeast and south of Brazil, as well as from other areas of the world, which still show M . canis as the most frequent microorganism isolated in Tinea capitis. Nippon Ishinkin Gakkai Zasshi, 2000, 41(4), 235 - 9 {Recent knowledge allowing diagnosis and treatment of deep-seated trichosporonosis}; Yamakami Y et al.; Deep-seated trichosporonosis is a lethal opportunistic infection in immunocompromised patients . For the rapid diagnosis of this condition, we developed a novel nested-PCR assay that detects DNA specific for clinically important strains of Trichosporon in serum of patients with disseminated trichosporonosis . In this assay, two sets of oligonucleotide primers were derived from the sequence of 26 S ribosomal RNA genes of T . asahii . The specific fragment was amplified from T . asahii and T . mucoides but not from other microorganisms . In a retrospective study using serum samples of patients with disseminated trichosporonosis, the specific fragment was detected in 64% (7 of 11) . To treat this infection, we studied the efficacy of rhG-CSF alone and in combination with antifungal agents against disseminated trichosporonosis in neutropenic mice . The results suggested that rhG-CSF might be a useful immunomodulator against Trichosporon infections and the therapeutic outcome might be better when used in combination with antifungal agents. Orthop Nurs, 2000 Mar-Apr, 19(2), 19 - 25; quiz 26-8 How drug-resistant microorganisms affect nursing; Glover TL; Although antibiotics have improved the mortality and morbidity associated with infectious disease, antibiotic mismanagement has created drug-resistant microorganisms, which are present in the environment outside the hospital . In the hospital, drug-resistant microorganisms require Contact Isolation, a transmission-based isolation recommended by the Centers for Disease Control and Prevention . The nurse's role in preventing the spread of drug-resistant microorganisms includes using appropriate infection control and isolation guidelines (especially handwashing), working with other health care workers to maintain appropriate infection control standards at all times, and teaching patients and families about infection control and antibiotic management. J Antimicrob Chemother, 2000 Nov, 46(5), 685 - 93 In vitro inactivation of Chlamydia trachomatis and of a panel of DNA (HSV-2, CMV, adenovirus, BK virus) and RNA (RSV, enterovirus) viruses by the spermicide benzalkonium chloride; Belec L et al.; Kinetics of inactivation by the detergent spermicide benzalkonium chloride (BZK) of Chlamydia trachomatis and of a panel of DNA viruses {herpes simplex virus hominis type 2 (HSV-2), cytomegalovirus (CMV), adenovirus (ADV) and BK virus (BKV)} and RNA {respiratory syncytial virus (RSV) and enterovirus (ENV)} were established in accordance with a standardized in vitro protocol . After a 5 min incubation, inactivation of >95% of HSV-2 and CMV was obtained at a concentration of 0.0025% (w/v) (25 Ig/L); concentrations as low as 0.0005%, 0.0050% and 0.0125%, induced a 3.0 log10 reduction in infectivity of HSV-2 and CMV, RSV and ADV, respectively . After a 60 min incubation, concentrations of 0.0125% and 0.050% provided a 3.0 log10 reduction in infectivity of ENV and BKV, respectively . These features indicate that sensitivity to BZK was very high (HSV-2 and CMV) or high (RSV) for enveloped viruses, intermediate (ADV) or low (ENV and BKV) for non-enveloped viruses . Furthermore, BZK had marked antichlamydial activity, showing >99% killing after only a 1 min incubation at a concentration of 0.00125% . BZK demonstrates potent in vitro activity against the majority of microorganisms causing sexually transmitted infectious diseases, including those acting as major genital cofactors of human immunodeficiency virus transmission . These attributes qualify BZK as a particularly attractive candidate for microbicide development. J Cardiovasc Nurs, 2000 Oct, 15(1), 13 - 26 Inflammation and infection in acute coronary syndrome; Albert NM; Basic science research has revealed that monocytes and macrophages are important factors in atherogenesis . Immune system activation occurs at all stages of plaque formation, from the fatty streak to an advanced, complicated lesion . The inflammatory response not only stimulates changes in coronary artery endothelial cells causing endothelial injury and dysfunction, but also plays a role in plaque instability and rupture . New perspectives of atherosclerosis and acute coronary syndromes will be discussed in relation to inflammation . In addition, discussion will focus on bacterial and viral infectious microorganisms as a potential factor that may induce and promote inflammation and lead to acute coronary events . Clinical studies in humans have provided insight relating inflammation and infectious agents to atherosclerosis and plaque vulnerability . Other studies focus on specific interventions that may aid in diagnosis and treatment. Microbiol Res, 2000 Sep, 155(3), 179 - 95 Reliable amplification of actin genes facilitates deep-level phylogeny; Voigt K et al.; The gene for actin as a highly conserved and functionally essential genetic element is developing into a major tool for phylogenetic analysis within a broad organismic range . We therefore propose a set of universally applicable primers that allow reliable amplification of actin genes . For primer construction the amino acid sequences of 57 actin genes comprising fungi, animals, plants and protists were analysed, aligned and used for the definition of six well-conserved regions which are suitable as priming sites in PCR amplification experiments . Ten primers were designed for specific in vitro amplification of actin gene fragments from a wide range of microorganisms . The corresponding gene fragments provide a strong basis to isolate nearly complete actin genes for further molecular characterization and for establishing phylogenies based on actin gene trees. Expert Opin Investig Drugs, 2000 Jun, 9(6), 1243 - 56 Microbial pathogens and apoptotic anticancer therapy; Pasechnik V; In spite of tremendous efforts to control cancer, the mortality associated with this disease has been increasing in developed countries in the recent decades . Inadequate efficiency of existing therapeutic regimens and the rise of multi-drug resistant cancer cells are the main factors which require a broadening of investigations into novel anticancer strategies . Enhancement of apoptosis in tumours has been suggested recently as a new anticancer strategy . It targets the disruption of equilibrium between cell proliferation and cell death in tumours and suggests to restore it through the use of pharmacological agents or genetic approaches . Apoptotic therapy has attracted many groups of investigators and several companies have entered the race to develop the first generation of apoptotic anticancer agents . The review discusses the role that pathogenic microorganisms may have as the source of agents for apoptotic therapy. Rev Esp Cardiol, 2000 Oct, 53(10), 1384 - 96 {Practice guidelines of the Spanish Society of Cardiology on endocarditis}; Valles F et al.; Infectious endocarditis is a disease which mainly involves the cardiac valves . It has a bad prognosis and is caused by a great variety of microorganisms . Prophylaxis is important although the effectiveness and the best way to achieve it remain unclear . Recommendations are herein presented . The diagnosis is based on clinical, bacteriological, and echocardiographic findings mainly based on Duke's criteria . Transthoracic and transesophageal echography are not only of diagnostic value but are also a tool to determine the therapy to follow . Antibiotic therapy should be selected according to the organisms isolated and their in vitro susceptibility . Guidelines for empirical antibiotic therapy in cases of negative cultures are also included . Lastly, indications and time for surgery are discussed. Biochim Biophys Acta, 2000 Oct 18, 1482(1-2), 272 - 83 Human neutrophil gelatinase-associated lipocalin and homologous proteins in rat and mouse; Kjeldsen L et al.; Neutrophil gelatinase-associated lipocalin (NGAL) is a 25-kDa lipocalin originally purified from human neutrophils . It exists in monomeric and homo- and heterodimeric forms, the latter as a dimer with human neutrophil gelatinase . It is secreted from specific granules of activated human neutrophils . Homologous proteins have been identified in mouse (24p3/uterocalin) and rat (alpha(2)-microglobulin-related protein/neu-related lipocalin) . Structural data have confirmed a typical lipocalin fold of NGAL with an eight-stranded beta-barrel, but with an unusually large cavity lined with more polar and positively charged amino acid residues than normally seen in lipocalins . Chemotactic formyl-peptides from bacteria have been proposed as ligands of NGAL, but binding experiments and the structure of NGAL do not support this hypothesis . Besides neutrophils, NGAL is expressed in most tissues normally exposed to microorganisms, and its synthesis is induced in epithelial cells during inflammation . This may indicate either a microbicidal activity of NGAL or a role in regulation of inflammation or cellular growth, putative functions yet to be demonstrated. Crit Care Med, 2000 Oct, 28(10), 3412 - 6 Pharmacokinetics and dosing regimen of meropenem in critically ill patients receiving continuous venovenous hemofiltration; Ververs TF et al.; OBJECTIVE: To study the pharmacokinetics of meropenem in critically ill patients with acute renal failure receiving continuous venovenous hemofiltration (CWHF) . DESIGN: Prospective, open-labeled study . SETTING: Medical intensive care unit of the University Medical Center Utrecht . PATIENTS: Five critically ill patients receiving CWHF for acute renal failure treated with meropenem for documented or suspected bacterial infection . INTERVENTION: All patients received meropenem (500 mg) administered intravenously every 12 hrs . Plasma samples and ultrafiltrate aliquots were collected during one dosing interval . MEASUREMENTS AND RESULTS: Mean age and body weight of the patients studied were 46.6 yrs (range, 28-61 yrs) and 85.8 kg (range, 70-100 kg), respectively . The following pharmacokinetic variables for meropenem were obtained: mean peak plasma concentration was 24.5 +/- 7.2 mg/L, mean trough plasma concentration was 3.0 +/- 0.9 mg/L, mean terminal elimination half-life was 6.37 +/- 1.96 hrs, mean total plasma clearance was 4.57 +/- 0.89 L/hr, mean CWHF clearance was 1.03 +/- 0.42 L/hr, mean nonrenal clearance was 3.54 +/- 1.06 L/hr, and mean volume of distribution was 0.37 +/- 0.15 L/kg . CONCLUSION: In critically ill patients with acute renal failure, nonrenal clearance became the main elimination route . CWHF substantially contributed to the clearance of meropenem (23% of mean total plasma clearance) . We recommend meropenem to be dosed at 500 mg intravenously every 12 hrs in patients receiving CWHF, according to our operational characteristics . This dosing regimen resulted in adequate trough plasma levels for susceptible microorganisms. Appl Environ Microbiol, 2000 Nov, 66(11), 4758 - 63 Identification of a universally primed-PCR-derived sequence-characterized amplified region marker for an antagonistic strain of Clonostachys rosea and development of a strain-specific PCR detection assay; Bulat SA et al.; We developed a PCR detection method that selectively recognizes a single biological control agent and demonstrated that universally primed PCR (UP-PCR) can identify strain-specific markers . Antagonistic strains of Clonostachys rosea (syn . Gliocladium roseum) were screened by UP-PCR, and a strain-specific marker was identified for strain GR5 . No significant sequence homology was found between this marker and any other sequences in the databases . Southern blot analysis of the PCR product revealed that the marker represented a single-copy sequence specific for strain GR5 . The marker was converted into a sequence-characterized amplified region (SCAR), and a specific PCR primer pair was designed . Eighty-two strains, isolated primarily from Danish soils, and 31 soil samples, originating from different localities, were tested, and this specificity was confirmed . Two strains responded to the SCAR primers under suboptimal PCR conditions, and the amplified sequences from these strains were similar, but not identical, to the GR5 marker . Soil assays in which total DNA was extracted from GR5-infested and noninoculated field soils showed that the SCAR primers could detect GR5 in a pool of mixed DNA and that no other soil microorganisms present contained sequences amplified by the primers . The assay developed will be useful for monitoring biological control agents released into natural field soil. Appl Environ Microbiol, 2000 Nov, 66(11), 4625 - 33 Persistence of selected Spartina alterniflora rhizoplane diazotrophs exposed to natural and manipulated environmental variability; Bagwell CE et al.; Rhizoplane-rhizosphere nitrogen-fixing microorganisms (diazotrophs) are thought to provide a major source of biologically available nitrogen in salt marshes dominated by Spartina alterniflora . Compositional and functional stability has been demonstrated for this important functional group; however, the quantitative responses of specific diazotroph populations to environmental variability have not been assessed . Changes in the relative abundances of selected rhizoplane diazotrophs in response to long-term fertilization were monitored quantitatively by reverse sample genome probing . Fertilization stimulated Spartina, with plant height nearly tripling after 1 year . Fertilization also resulted in significant changes in interstitial porewater parameters . Diazotrophic activity (acetylene reduction assay) was sensitive to the fertilization treatments and was inhibited in some plots on several sampling dates . However, inhibition was never consistent across all of the replicates within a treatment and activity always recovered . The rhizoplane diazotrophs were quite responsive to environmental variability and to experimental treatments, but none were displaced by either environmental variability or experimental treatments . All strains were detected consistently throughout this study, and extensive spatial heterogeneity in the distribution patterns of these organisms was observed . The physiological traits that differentiate the diazotroph populations presumably support competitiveness and niche specialization, resulting in the observed resilience of the diazotroph populations in the rhizosphere. Scand J Infect Dis, 2000, 32(5), 507 - 10 Mycobacterium tuberculosis drug resistance in Turkey, 1976-97; Bengisun JS et al.; Drug-resistant tuberculosis is increasing day by day and is a significant threat to tuberculosis control because there are few drugs effective against Mycobacterium tuberculosis . This study evaluates the resistance of the microorganism to primary anti-tuberculosis drugs over the 21-y period 1976-97 . Records from the bacteriology laboratory of the Department of Chest Diseases and Tuberculosis, Ankara Univer