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At least 739 records · Page 41Linked to original sources
PubMed1995

Administration of rHuGM-CSF activates monocyte reactive oxygen species secretion and adhesion molecule expression in vivo in patients following high-dose chemotherapy.

Microbicidal and cytocidal products of the respiratory burst and integrin adhesion molecule expression have been studied in monocytes from patients who received rHuGM-CSF during regeneration after high-dose chemotherapy. In this study, administration of rHuGM-CSF after high-dose chemotherapy significantly augmented the secretion of inducible products of the monocyte respiratory burst. Monocyte activation persisted for several weeks after the cessation of GM-CSF therapy. Under in vitro conditions that mimicked gram-negative (LPS) and gram-positive (opsonized Staphylococcus aureus) sepsis, the monocyte responded to such stimulation by exhibiting an enhanced release of hydrogen peroxide at both regeneration and several weeks later (P < 0.001). Similarly, GM-CSF administration significantly augmented the phenotypic expression of the beta 2-integrin adhesion molecules and allowed the leucocyte-specific selectin, LAM-1, and the beta 2-integrins to respond normally to inflammatory stimulation by LPS. We further present evidence that GM-CSF therapy restored the otherwise refractory status of monocytes to inflammatory stimulation that existed in those patients given chemotherapy alone. The restoration of monocyte responsiveness by GM-CSF following high-dose chemotherapy could be a potentially valuable and hitherto not described action of rHuGM-CSF on monocyte function. We conclude that administration of GM-CSF may have the potential for restoring as well as augmenting the anti-microbial and anti-tumour function of the monocyte after high-dose chemotherapy.

Adult↗
PubMedDate not supplied

[A probiotic as an antagonist of bacterial translocation in experimental pancreatitis].

Infection is the most common cause of death in acute pancreatitis. Earlier studies have demonstrated that early enteral nutrition decreases microbial translocation, upregulates the immune function and reduces septic complications and mortality. Lactobacillus plantarum (Lp) has been shown to be effective in reducing egress of endotoxin and microbial strain that showed very high adherence power to gut mucosa. We adopted a model of acute pancreatitis induced by isolation and ligation of biliopancreatic duct in adult Lewis rats. Three groups were studied: A. control group (sham operation); B. induced pancreatitis, no further treatment; C. Induced pancreatitis + gavage with 5 ml/day of a suspension of Lp 299 v in a dose of 0.5-1.0 x 10(9)/ml during 4 days before and 4 days after induction of pancreatitis. All animals were sacrificed after 96 hours. Histological studies and microbiological analyses were performed. Forty out of 55 animals showed signs of severe pancreatitis on sacrifice after 96 hours. Only these animals were further studied. In group A, we found only 1/20 bacteria in mesenteric nodes (MN). Pathogenic microrganisms were found in the non-treated group in MN in 14/20 and in the pancreatic tissue in 10/20. In contrast, when kept on an umbrella of Lp 299 v, only 4/20 animals demonstrated growth of enteric bacteria in MN and 3/20 in pancreatic tissue. All of these results showed a significant reduction of infection in the treated groups. In our model, Lp 299 v is effective in preventing microbial translocation in experimental pancreatitis. Treatment with probiotic bacteria, such as Lactobacillus spp, seems to be a promising alternative as problems with antibiotic-resistant bacteria seem to accumulate.

Acute Disease↗
PubMed2001

Probiotics and functional foods in gastrointestinal disorders.

Probiotics are live microbial food supplements that benefit the host animal by improving intestinal microbial balance. When they are fed in yogurts, they can fall into the category of functional foods. Functional foods include these probiotics, prebiotics, and, to a certain extent, dietary fiber. Prebiotics are nondigestible food ingredients or supplements that alter the intestinal flora and stimulate the growth of healthy bacteria. Dietary fibers are part of plant foods that are nonstarch polysaccharides and are poorly digested or not digested by human enzymes. The physiologic process in which probiotics and functional foods affect the intestinal flora is through the balance of the intestinal microecology. This review looks at the four major components of intestinal microecology and describes the probiotics in use today and their clinical relevance. Although probiotics hold great promise and appear to be useful in some settings, more clinical study is needed to firmly establish the relevance of probiotic therapy.

Dietary Fiber↗
PubMed2002

Probiotics and Functional Foods in Gastrointestinal Disorders.

Probiotics are live microbial food supplements that benefit the host animal by improving intestinal microbial balance. When they are fed in yogurts, they can fall into the category of functional foods. Functional foods include these probiotics, prebiotics, and, to a certain extent, dietary fiber. Prebiotics are nondigestible food ingredients or supplements that alter the intestinal flora and stimulate the growth of healthy bacteria. Dietary fibers are part of plant foods that are nonstarch polysaccharides and are poorly digested or not digested by human enzymes. The physiologic process in which probiotics and functional foods affect the intestinal flora is through the balance of the intestinal microecology. This review looks at the four major components of intestinal microecology and describes the probiotics in use today and their clinical relevance. Although probiotics hold great promise and appear to be useful in some settings, more clinical study is needed to firmly establish the relevance of probiotic therapy.

Journal Article↗
PubMed2003

The biological component of the life support system for a Martian expedition.

Ground-based experiments at RF SSC-IBMP RAS (State Science Center of Russian Federation--Institute of Biomedical Problems of Russian Academia of Science) were aimed at overall studies of a human-unicellular algae-mineralization LSS (life support system) model. The system was 15 m3 in volume. It contained 45 L of algal suspension with a dry substance density of 10-12 g per liter; water volume, including the algal suspension, was 59 L. More sophisticated model systems with partial substitution of unicellular algae with higher plates (crop area of 15 m2) were tested in three experiments from 1.5 to 2 months in duration. The experiments demonstrated that LSS employing the unicellular algae play not only a macrofunction (regeneration of atmosphere and water) but also carry some other functions (purification of atmosphere, formation of microbial cenosis etc.) providing an adequate human environment. It is also important that functional reliability of the algal regenerative subsystem is secured by a huge number of cells able, in the event of death of a part of population, to recover in the shortest possible time the size of population and, hence, functionality of the LSS autotrophic component. For a long period of time a Martian crew will be detached from Earth's biosphere and for this reason LSS of their vehicle must be highly reliable, robust and redundant. One of the approaches to LSS redundancy is installation of two systems with different but equally efficient regeneration technologies, i.e. physical-chemical and biological. At best, these two systems should operate in parallel sharing the function of regeneration of the human environment. In case of failure or a sharp deterioration in performance of one system the other will, by way of redundancy, increase its throughput to make up for the loss. This LSS design will enable simultaneous handling of a number of critical problems including adequate satisfaction of human environmental needs.

Air Conditioning↗
PubMed1995

Functional characterization of peripheral blood neutrophils in patients with hyperthyroidism.

The thyroid hormones may exert an important effect on neutrophil functions which play a key role in the defence against microbial pathogens. Therefore investigations of the biological functions of neutrophils in peripheral blood of 80 women with hyperthyroidism were performed. The following functions of neutrophils were examined: nitroblue tetrazolium (NBT) reduction ability, phagocytosis, adherence to fibers as well as spontaneous migration of leukocytes and activity of lysozyme in serum. The total number of leukocytes and neutrophils was also determined. The results were compared with those in the control group consisting of 40 healthy women. The data show that in patients with hyperthyroidism, the number of leukocytes and neutrophils was decreased (respectively 4.90 x 10(9) +/- 1.20, 2.70 x 10(9) +/- 0.54 in patients, and 5.40 x 10(9) +/- 1.30, 3.00 x 10(9) +/- 0.74 in the control subjects), index of spontaneous reduction NBT was increased (17.1% +/- 4.5 in patients and 11.1% +/- 4.5 in the control group), index of phagocytosing cells was decreased (63.0% +/- 16.0, 80.3% +/- 14.0 in patients and 72.2% +/- 12.1, 87.4% +/- 12.0 in the control group), an increase in adherence (71% +/- 17 in patients and 58% +/- 10 in the control subjects), and a decrease in the lysozyme activity in undiluted and diluted serum was found (185 IU/ml +/- 85,209 IU/ml +/- 78 in patients and 284 IU/ml +/- 84,352 IU/ml +/- 140 in the control group).

Adult↗
PubMed2006

In vitro system for high-throughput screening of random peptide libraries for antimicrobial peptides that recognize bacterial membranes.

Antibacterial peptides have been isolated from a wide range of species. Some of these peptides act on microbial membranes, disrupting their barrier function. With the increasing development of antibiotic resistance by bacteria, these antibacterial peptides, which have a new mode of action, have attracted interest as antibacterial agents. To date, however, few effective high-throughput approaches have been developed for designing and screening peptides that act selectively on microbial membranes. In vitro display techniques are powerful tools to select biologically functional peptides from peptide libraries. Here, we used the ribosome display system to form peptide-ribosome-mRNA complexes in vitro from nucleotides encoding a peptide library, as well as immobilized model membranes, to select specific sequences that recognize bacterial membranes. This combination of ribosome display and immobilized model membranes was effective as an in vitro high-throughput screening system and enabled us to identify motif sequences (ALR, KVL) that selectively recognized the bacterial membrane. Owing to host toxicity, it was not possible to enrich any sequence expected to show antimicrobial activity using another in vitro system, e.g. phage display. The synthetic peptides designed from these enriched motifs acted selectively on the bacterial model membrane and showed antibacterial activity. Moreover, the motif sequence conferred selectivity onto native peptides lacking selectivity, and decreased mammalian cell toxicity of native peptides without decreasing their antibacterial activity.

Amino Acid Sequence↗
PubMed2006

Homogeneous versus heterogeneous probes for microbial ecological microarrays.

Microbial ecological microarrays have been developed for investigating the composition and functions of microorganism communities in environmental niches. These arrays include microbial identification microarrays, which use oligonucleotides, gene fragments or microbial genomes as probes. In this article, the advantages and disadvantages of each type of probe are reviewed. Oligonucleotide probes are currently useful for probing uncultivated bacteria that are not amenable to gene fragment probing, whereas the functional gene fragments amplified randomly from microbial genomes require phylogenetic and hierarchical categorization before use as microbial identification probes, despite their high resolution for both specificity and sensitivity. Until more bacteria are sequenced and gene fragment probes are thoroughly validated, heterogeneous bacterial genome probes will provide a simple, sensitive and quantitative tool for exploring the ecosystem structure.

Bacteria↗
PubMed1999

Spatial distribution of respiratory activity in Pseudomonas putida 54G biofilms degrading volatile organic compounds (VOC).

All over the world, Microbial systems are used to clean soils, waters and air streams that have been contaminated with volatile organic compounds (VOC). Information about the structure and function of the microbes that metabolize these contaminants can be gained by studying these microbial systems. Here we describe the spatial patterns of respiratory activity in Pseudomonas putida 54G aerobic biofilms degrading two VOC, toluene and ethanol. Oxygen concentration profiles within the biofilm were measured using microsensors. These profiles are thought to be most accurate reflection of the structure and function of aerobic microbial biofilms. The degrading process certainly imposed a structural and functional patterns on the microbial biofilm community growing at the expense of the VOC substrate. Cryosectioning coupled with the staining of biofilm samples confirmed a high respiratory activity near the substratum, that decreased towards the biofilm/fluid interface. The accumulation of inactive cells in the outer biofilm layer protects the inner biofilm from high concentrations of toxic compounds and also limits the degradation rate. This stratification phenomenon appeared to be a general pattern for P. putida 54G biofilms degrading VOC.

Biofilms↗
PubMed2006

Antimicrobial activities of silver used as a polymerization catalyst for a wound-healing matrix.

Wound healing is a complex and orchestrated process that re-establishes the barrier and other functions of the skin. While wound healing proceeds apace in healthy individual, bacterial overgrowth and infection disrupts this process with significant morbidity and mortality. As such, any artificial matrix to promote wound healing must also control infecting microbes. We had earlier developed a two-part space-conforming gel backbone based on polyethyleneglycol (PEG) or lactose, which used ionic silver as the catalyst for gelation. As silver is widely used as an in vitro antimicrobial, use of silver as a catalyst for gelation provided the opportunity to assess its function as an anti-microbial agent in the gels. We found that these gels show bacteriostatic and bactericidal activity for a range of Gram-negative and Gram-positive organisms, including aerobic as well as anaerobic bacteria. This activity lasted for days, as silver leached out of the formed gels over a day in the manner of second-order decay. Importantly the gels did not limit either cell growth or viability, though cell migration was affected. Adding collagen I fragments to the gels corrected this effect on cell migration. We also found that the PEG gel did not interfere with hemostasis. These observations provide the basis for use of the gel backbones for incorporation of anesthetic agents and factors that promote wound repair. In conclusion, silver ions can serve dual functions of catalyzing gelation and providing anti-microbial properties to a biocompatible polymer.

Anti-Bacterial Agents↗
PubMed2005

Application of metabolome data in functional genomics: a conceptual strategy.

A gene with yet unknown physiological function can be studied by changing its expression level followed by analysis of the resulting phenotype. This type of functional genomics study can be complicated by the occurrence of 'silent mutations', the phenotypes of which are not easily observable in terms of metabolic fluxes (e.g., the growth rate). Nevertheless, genetic alteration may give rise to significant yet complicated changes in the metabolome. We propose here a conceptual functional genomics strategy based on microbial metabolome data, which identifies changes in in vivo enzyme activities in the mutants. These predicted changes are used to formulate hypotheses to infer unknown gene functions. The required metabolome data can be obtained solely from high-throughput mass spectrometry analysis, which provides the following in vivo information: (1) the metabolite concentrations in the reference and the mutant strain; (2) the metabolic fluxes in both strains and (3) the enzyme kinetic parameters of the reference strain. We demonstrate in silico that changes in enzyme activities can be accurately predicted by this approach, even in 'silent mutants'.

Genome, Fungal↗
PubMed2002

In situ fixation of metals in soils using bauxite residue: biological effects.

Soils polluted with heavy metals can cause phytotoxicity and exhibit impared microbial activities. In this paper we evaluate the responses of different biological endpoints to in situ remediation processes. Three soil amendments (red mud, beringite and lime) were applied to two soils polluted by heavy metals. Oilseed rape, wheat, pea and lettuce were grown successively in pots on the untreated and amended soils and their yield and metal uptake were determined. A suite of microbial tests (lux-marked biosensors, Biolog and soil microbial biomass) were performed to determine the effect of the soil amendments on the functionality and size of the soil microbial community. In both soils all three amendments reduced phytotoxicity of heavy metals, enhanced plant yields and decreased the metal concentrations in plants. The red mud treatment also increased soil microbial biomass significantly. The microbial biosensors responded positively to the remediation treatments in the industrially-contaminated soil used in the experiment. Red mud applied at 2% of soil weight was as effective as beringite applied at 5%. The results also showed that since the biological systems tested respond differently to the alleviation of metal toxicity, a suite of biological assays should be used to assess soil remediation processes.

Aluminum Oxide↗
PubMedDate not supplied

Multiple functions of thioredoxins.

Reduced thioredoxins from microbial and plant cells, both of cytoplasmic or chloroplast origin, are interchangeable in stimulating such diverse enzyme activities as ribonucleoside diphosphate reductase (E. coli), PAPS sulfotransferase (Synechococcus), and fructose-1,6-bis-phosphatase (from spinach) in vitro. It is suggested that reduced thioredoxins are unspecific, multifunctional cellular proteins while in contrast the oxidized froms require specific enzymes for their reduction.

Bacterial Proteins↗
PubMed2003

In the belly of the beast: subversion of macrophage proinflammatory signalling cascades during Toxoplasma gondii infection.

Macrophages (MØ) are used as the intracellular niche by several bacterial and protozoan microorganisms. Such microbial pathogens adopt diverse strategies to avoid MØ microbicidal effects. Recent insights into the Toxoplasma gondii-MØ interaction reveal novel ways that intracellular parasites subvert MØ function. In contrast to some microbial pathogens, Toxoplasma infection is not silent but induces rapid activation of transcription factors such as STAT-1 and NFkappaB. However, the parasite blocks nuclear translocation of both factors, and MØ cannot produce IL-12 or TNF-alpha when subsequently triggered with lipopolysaccharide. The nuclear import blockade is lifted 24 h after infection, but cells remain actively suppressed in TNF-alpha production. Nevertheless, IL-12 synthesis is initiated at this later time point. Toxoplasma gondii-induced production of this cytokine occurs through both MyD88- and CCR5-dependent pathways. The balance of cytokine subversion and stimulation during infection probably results from the parasite's need to simultaneously avoid immune elimination and trigger immunity to prevent host death.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Mannan-binding lectin (MBL) gene polymorphisms in ulcerative colitis and Crohn's disease.

The inflammatory bowel diseases (IBD), Crohn's disease (CD), and ulcerative colitis (UC), are complex multifactorial traits involving both environmental and genetic factors. Mannan-binding lectin (MBL) plays an important role in non-specific immunity and complement activation. Point mutations in codons 52, 54 and 57 of exon 1 of the MBL gene are associated with decreased MBL plasma concentrations and increased susceptibility to various infectious diseases. If these MBL mutations could lead to susceptibility to putative IBD-etiological microbial agents, or could temper the complement-mediated mucosal damage in IBD, MBL could function as the link between certain microbial, immunological and genetic factors in IBD. In this study, we investigated the presence of the codon 52, 54 and 57 mutations of the MBL gene in 431 unrelated IBD patients, 112 affected and 141 unaffected first-degree relatives, and 308 healthy control individuals. In the group of sporadic IBD patients (n = 340), the frequency of the investigated MBL variants was significantly lower in UC patients when compared with CD patients (P = 0.01) and with controls (P = 0.02). These results suggest that MBL mutations which decrease the formation of functional MBL could protect against the clinical development of sporadic UC, but not of CD. This could be explained by the differential T-helper response in both diseases.

Adolescent↗
PubMedDate not supplied

How will bioinformatics influence metabolic engineering?

Ten microbial genomes have been fully sequenced to date, and the sequencing of many more genomes is expected to be completed before the end of the century. The assignment of function to open reading frames (ORFs) is progressing, and for some genomes over 70% of functional assignments have been made. The majority of the assigned ORFs relate to metabolic functions. Thus, the complete genetic and biochemical functions of a number of microbial cells may be soon available. From a metabolic engineering standpoint, these developments open a new realm of possibilities. Metabolic analysis and engineering strategies can now be built on a sound genomic basis. An important question that now arises; how should these tasks be approached? Flux-balance analysis (FBA) has the potential to play an important role. It is based on the fundamental principle of mass conservation. It requires only the stoichiometric matrix, the metabolic demands, and some strain specific parameters. Importantly, no enzymatic kinetic data is required. In this article, we show how the genomically defined microbial metabolic genotypes can be analyzed by FBA. Fundamental concepts of metabolic genotype, metabolic phenotype, metabolic redundancy and robustness are defined and examples of their use given. We discuss the advantage of this approach, and how FBA is expected to find uses in the near future. FBA is likely to become an important analysis tool for genomically based approaches to metabolic engineering, strain design, and development.

Computational Biology↗
PubMed2006

Microbial immune suppression mediated by direct engagement of inhibitory Fc receptor.

A microbial polysaccharide (glucuronoxylomannan (GXM)) exerts potent immunosuppression by direct engagement to immunoinhibitory receptor FcgammaRIIB. Activation of FcgammaRIIB by GXM leads to the recruitment and phosphorylation of SHIP that prevents IkappaBalpha activation. The FcgammaRIIB blockade inhibits GXM-induced IL-10 production and induces TNF-alpha secretion. GXM quenches LPS-induced TNF-alpha release via FcgammaRIIB. The addition of mAb to GXM reverses GXM-induced immunosuppression by shifting recognition from FcgammaRIIB to FcgammaRIIA. These findings indicate a novel mechanism by which microbial products can impair immune function through direct stimulation of an inhibitory receptor. Furthermore, our observations provide a new mechanism for the ability of specific Ab to reverse the immune inhibitory effects of certain microbial products.

Antibodies, Monoclonal↗
PubMedDate not supplied

[Regulation of the biomass and activity of soil microorganisms by microfauna].

Microcosm experiments showed that the microbial biomass and the respiration activity in soil were regulated by nematodes. Depending on nematode number and plant residue composition, the trophic activity of nematodes can either stimulate or inhibit microbial growth and respiration as compared to soil containing no nematodes. The stimulating effect was observed when nitrogen-free (starch) or low-nitrogen (wheat straw, C:N = 87) organic substrates were applied. Inhibition occurred when a substrate rich in nitrogen (alfalfa meal, C:N = 28) was decomposed and the nematode population exceeded the naturally occurring level. A conceptual model was developed to describe trophic regulation by microfauna (nematodes) of the microbial productivity and respiration activity and decomposition of not readily decomposable organic matter in soil. The stimulating and inhibiting influence of microfauna on soil microorganisms was not a linear function of the rate of microbial consumption by nematodes. These effects are largely associated with the induced change in the physiological state of microorganisms rather than with the mobilization of biogenic elements from the decomposed microbial biomass.

Animals↗