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PubMed2000

Tolerance and immunity in the intestinal immune system.

The intestinal immune system must guard the body against invasion by pathogens while avoiding a response to the many potential antigens present in food. In the absence of the inflammatory stimuli necessary to elicit an immune response, oral administration of soluble protein antigens induces antigen-specific systemic nonresponsiveness. Recent studies have shown that peripheral nonresponsiveness to orally administered antigen is preceded by transient T-cell activation and is due primarily to the induction of functional T-cell anergy. The microenvironment of the gut-associated lymphoid tissue plays a central role in orally induced nonresponsiveness by supporting the growth of regulatory T cells that maintain intestinal homeostasis in the face of constant antigenic challenge. The transfer of nonresponsiveness by peripheral T cells from antigen-fed mice suggests that these-gut-derived regulatory cells also function in peripheral sites. When oral antigens are presented with adjuvants (microbial products that activate the innate immune system) an adaptive immune response is induced to this normally tolerogenic form of antigen. This review examines recent work that has provided new insight into the regulation of tolerance and immunity in the intestinal immune system.

Animals↗
PubMedDate not supplied

Inhibition of bacterial growth by granulocytes measured by an automated technique.

Granulocytes, collected by several methods, were assayed for antibacterial activity utilizing a technique originally developed for automated antibiotic susceptibility testing. The granulocytes were incubated with either Escherichia coli or Staphylococcus for one hour at 37 degrees C and were then separated from the suspension by gentle centrifugation at 170 g. The bacteria remaining in the supernatant broth were incubated in culture medium (eugonic broth) and their growth density was compared with diluted controls (without granulocytes) by measurement in an Autobac I (an automated nephelometer). Measurements of the density of growth at 30 minute intervals showed a marked delay in the development of density suggesting only small numbers of organisms remained after incubation with granulocytes. Once density was measurable, the rate of growth appeared similar to controls. After 2.5 hours in the Atuobac I, the density of growth was used to determine the inhibitory effect of granulocytes. The density of growth was inversely related to the concentration of granulocytes present during the preincubation phase. Filtered granulocytes showed significantly lower inhibitory effect than centrifuged granulocytes. This rapid, inexpensive method of determining microbial growth appears to be adaptable as a measure of granulocyte function.

Autoanalysis↗
PubMed1979

Absence of neutral protease and alkaline phosphatase in neutrophils of a case of hairy cell leukemia.

Enzymaticaly homogeneous fractions of lymphocytes, monocytes, and neutrophils were isolated by zonal centrifugation from peripheral blood of a patient with hairy cell leukemia, or leukemic reticuloendotheliosis, LRE,(with leukopenia, neutropenia, lymphocytosis, and massive splenomegaly). To detect enzymatic deficiencies, the cells were analyzed quantitatively for six leukocytic enzymes on three occasions: 1) before splenectomy, 2) 5 days after splenectomy, and 3) 6 weeks after splenectomy. Before splenectomy, the patient's cells showed moderate deficiency of beta-glucuronidase in lymphocytes and monocytes; server to modorate deficiency of lysozyme and myeloperoxidase in monocytes and granulocytes; and complete absence of neutral protease and alkaline phosphates in neutrophils. Full restoration of neutral protease and a three-fold rise in alkaline phosphatase activities occurred in the patient's neutrophils 5 days after splenectomy. Lysozyme and myeloperoxidase returned to normal in both monocytes and neutrophils of the patient. Six weeks following splenectomy, the alkaline phosphatase activity again disappeared from patient's neutrophils, although neutral protease remained normal. The patient's lymphocytes were unresponsive to PHA and PW mitogen before splenectomy but became responsive 6 weeks postoperatively. Monocytic transfomation into macrophges was supressed before and after splenectomy. The findings indicate that developmenally, in lymphocytic leukemia, a biochemical defect involves the patient's monocytes and neutrophils much more severely than it affects the leukemic lymphocytes. Functionally, the results partly explain the susceptibility of LRE patients to microbial infections.

Alkaline Phosphatase↗
PubMed1993

Interrelated approach to optimization of biosynthesis and chemical isolation of biologically active substances: the production of penicillinamidase by Escherichia coli and peptidohydrolase by Xanthomonas sp.

The solution to the problem of optimizing conditions for the isolation of biologically active substances (BAS) from microbial cells should be based on investigations of the structural and functional characteristics of cultures. Models of two bacterial cultures, of Escherichia coli and a Xanthomonas species, producing enzymes the localization of which differ, is described. The isolation of membrane-bound penicillinamidase from E. coli was optimal in the 'preautolysis' period, when the components of the cytoplasm autolysed but the membranes remained intact. In contrast, the isolation of the cytoplasmic enzyme peptidohydrolase from Xanthomonas sp. was optimal during the period when the cell membranes markedly changed. Thus the physiological state of the cultures and the localization of the BAS within the cells are important determinants for optimization of the isolation process. It follows that all stages of a technological process for the production of BAS, i.e. biosynthesis, chemical isolation, etc., should be interrelated for a successful outcome.

Culture Media↗
PubMed1997

[Microbial behavior and hurdles in Venezuelan intermediate moisture food].

Sixteen Venezuelan IMF, dairy products, dry-salted fish products, meat products and vegetable products (specially fruit products) were characterized; water activity, pH, moisture, acidity and humectants were determined, allowing us to identify the main hurdles. Parallelly the microbial profile and her evolution for each IMF were established in function of time and storage conditions. This information permits us to explain the different stability compartments for our IMF; simple modifications that will increase their stability are suggested. Water activity is not enough as a hurdle if it is not accompanied by an appropriate packaging, specially in tropical countries, that would limit water migrations.

Candy↗
PubMed1978

[Disorders of phagocytic and fungicide function of granulocytes in chronic muco-cutaneous candidiasis].

The granulocytes which are distributed by blood circulation close to the extern and intern body surfaces as well as in all organs protect the organism from microbial perils by phagocytosis and intracellular killing of bacteria and fungi so constituting a very important component of the granulocytic functions seriously impairs the host resistance and may entail a state of persisting infectious disease. As chronic mucocutaneous candidosis (CMCC) represents such a persistent generalized infection, we studied in vitro several functional activities of the granulocytes of 5 patients suffering from CMCC. 2 of them presented a non-familiar type of CMCC, the remaining 3 patients (father and 2 daughters) were subject to the hereditary type of CMCC. For comparison, by the same way we investigated the granulocytic functions of 51 clinically and immunologically healthy adult persons. Each of our 5 patients exhibited a reduced ability of the granulocytes to phagocytize and kill Candida albicans. In the CMCC family, the father had a marked deficiency of the oxidase activity of the granulocytes whereas in his daughters, the oxidase deficiency proved to be of a minor grade. In the sera of both daughters a phagocytosis inhibiting factor could be assumed to exist in addition to the granulocytic abnormalities. When heat-inactivated Candida albicans cells, however, were used for experiments, the granulocytes of each patient were able to phagocytize the germs at the same rate as did the granulocytes taken from the controls. With regard to alterations of the T cell function previously reported in CMCC, in all patients we also could demonstrate various symptoms of a T cell-dependent immunodeficiency. The results of the present in vitro-experiments furnish good evidence of a state of fundamental deficiency of the microphages in patients with CMCC, which may be the dominating cellular factor in the aetiopathogenesis of CMCC.

Adult↗
PubMed2000

Oxidative burst and cognate redox signalling reported by luciferase imaging: identification of a signal network that functions independently of ethylene, SA and Me-JA but is dependent on MAPKK activity.

Recognition of avirulent microbial pathogens activates an oxidative burst leading to the accumulation of reactive oxygen intermediates (ROIs), which are thought to integrate a diverse set of defence mechanisms resulting in the establishment of plant disease resistance. A novel transgenic Arabidopsis line containing a gst1:luc transgene was developed and employed to report the temporal and spatial dynamics of ROI accumulation and cognate redox signalling in response to attempted infection by avirulent strains of Pseudomonas syringae pv. tomato (Pst). Strong engagement of the oxidative burst was dependent on the presence of functional Pst hrpS and hrpA gene products. Experiments employing pharmacological agents suggested that at least two distinct sources, including an NADPH oxidase and a peroxidase-type enzyme, contributed to the generation of redox cues. The analysis of gst1 and pal1 gene expression in nahG, coi1 and etr1 plants suggested that engagement of the oxidative burst and cognate redox signalling functioned independently of salicylic acid, methyl jasmonate and ethylene. In contrast, studies using a panel of protein kinase and phosphatase inhibitors and in-gel kinase assays in these mutant backgrounds suggested that a 48 kDa mitogen-activated protein kinase (MAPK) activity was required for the activation of gst1 and pal1 in response to redox cues. Thus the engagement of a bifurcating redox signalling pathway possessing a MAPK module may contribute both to the establishment of plant disease resistance, and to the development of cellular protectant mechanisms.

Acetates↗
PubMed1976

Granulocyte function in untreated acute and chronic granulocytic leukemia.

Untreated patients with acute granulocytic leukemia showed impairment of microbicidal activity and,, in one, this was associated with myeloperoxidase deficiency and staphylococcal infection. In chronic granulocytic leukemia, there was no significant impairment of microbial killing. However, reduction in the capacity to reduce nitro-blue tetrazolium indicated some disturbance of neutrophil function in this disorder.

Adolescent↗
PubMed2003

Differences in hyporheic-zone microbial community structure along a heavy-metal contamination gradient.

The hyporheic zone of a river is nonphotic, has steep chemical and redox gradients, and has a heterotrophic food web based on the consumption of organic carbon entrained from downwelling surface water or from upwelling groundwater. The microbial communities in the hyporheic zone are an important component of these heterotrophic food webs and perform essential functions in lotic ecosystems. Using a suite of methods (denaturing gradient gel electrophoresis, 16S rRNA phylogeny, phospholipid fatty acid analysis, direct microscopic enumeration, and quantitative PCR), we compared the microbial communities inhabiting the hyporheic zone of six different river sites that encompass a wide range of sediment metal loads resulting from large base-metal mining activity in the region. There was no correlation between sediment metal content and the total hyporheic microbial biomass present within each site. However, microbial community structure showed a significant linear relationship with the sediment metal loads. The abundances of four phylogenetic groups (groups I, II, III, and IV) most closely related to alpha-, beta-, and gamma-proteobacteria and the cyanobacteria, respectively, were determined. The sediment metal content gradient was positively correlated with group III abundance and negatively correlated with group II abundance. No correlation was apparent with regard to group I or IV abundance. This is the first documentation of a relationship between fluvially deposited heavy-metal contamination and hyporheic microbial community structure. The information presented here may be useful in predicting long-term effects of heavy-metal contamination in streams and provides a basis for further studies of metal effects on hyporheic microbial communities.

Alphaproteobacteria↗
PubMed2003

Identification and functional analysis of tumor-infiltrating plasmacytoid dendritic cells in head and neck cancer.

The antitumor activity of IFN-alpha is well established. However, the role of the plasmacytoid dendritic cell (PDC), the major producer of IFN-alpha upon viral infection, in tumor biology is unknown. We sought to study the presence and function of PDC in a human solid tumor. Here, we demonstrate that PDCs infiltrate tumor tissue of patients with head and neck squamous cell carcinoma (HNSCC). Functional activity of PDC was examined by using CpG motif containing oligonucleotides, a defined microbial stimulus for PDCs (recognized via toll-like receptor 9). We found that HNSCC diminished the ability of PDC to produce IFN-alpha in response to CpG motif containing oligonucleotide. Tumor-induced down-regulation of toll-like receptor 9 was identified as one mechanism likely contributing to impaired PDC function within the tumor environment. In tumor-draining lymph nodes, suppression of CpG-induced IFN-alpha production was less pronounced than in single-cell suspensions of primary tumor tissue. In these lymph nodes, CpG-induced IFN-alpha production was associated with increased levels of interferon-induced protein 10 and IFN-gamma and activation of CD4 and CD8 T cells. These results show for the first time the presence of PDCs in human solid tumor tissue and that tumors suppress the capacity of PDCs to produce IFN-alpha. PDCs, which in the absence of appropriate stimulation are reported to promote regulatory CD8 T cells, may contribute to an impaired T-cell-mediated immune response in HNSCC.

Adolescent↗
PubMed2003

On the nature of gene innovation: duplication patterns in microbial genomes.

Gene duplication is considered a major force in gene family expansion and gene innovation. As gene copies assume novel functions, they must avoid periods of neutrality or be deleted from the genome. Current opinions state that copies avoid neutrality through gene dosage effects. These copies are therefore selected from an early stage. This study concentrates on the flow of copies from recent duplication to gene innovation. We have studied 21 microbial genomes using amino acid divergence to describe paralog evolution in the long-term perspective. Five of these were studied in closer detail using nucleotide divergence for a shorter perspective. It was found that rates of duplication and deletion are high, with only a small fraction of duplications retained and apparently selected. This leads to a steady accumulation of paralogs, which seems to be of a similar magnitude in most of the genomes. Furthermore, it is found that genes of high expression level, as measured by their codon bias, are strongly underrepresented among the most recent duplications. Based on these and other observations, it is suggested that gene innovation is driven by amplification of weak, ancillary functions rather than strong, established functions.

DNA Transposable Elements↗
PubMed1989

Clinical and pharmacokinetic aspects of ciprofloxacin in the treatment of acute exacerbations of pseudomonas infection in cystic fibrosis patients.

Twelve cystic fibrosis patients, aged over 18, who had developed an acute respiratory exacerbation and who had Pseudomonas species isolated from their sputum, were entered into a clinical trial involving ciprofloxacin. The dosage regimen was 100 mg iv followed by 500 mg twice daily orally if less than 40 kg in weight and 200 mg iv followed by 750 mg twice daily orally if greater than 40 kg. Ciprofloxacin was well tolerated with no major side effects, except in one patient who withdrew after onset of headaches and generalized aches and pains. Eleven of the 12 patients showed clinical improvement at the end of the treatment period as determined by weight gain, Shwachman Score, Chrispin Norman Score and pulmonary function tests. MICs of Pseudomonas species isolated from the sputum at the start of the trial were in the range 0.25-4 mg/l. During therapy, sensitivity of isolates decreased and did not return to starting levels at the end of a four week follow-up period. Pharmacokinetic parameters were similar to those reported for fasting healthy volunteers by other workers except for bioavailability which was reduced in the non-fasting patients.

Administration, Oral↗
PubMed2005

Phylogenetic detection of conserved gene clusters in microbial genomes.

BACKGROUND: Microbial genomes contain an abundance of genes with conserved proximity forming clusters on the chromosome. However, the conservation can be a result of many factors such as vertical inheritance, or functional selection. Thus, identification of conserved gene clusters that are under functional selection provides an effective channel for gene annotation, microarray screening, and pathway reconstruction. The problem of devising a robust method to identify these conserved gene clusters and to evaluate the significance of the conservation in multiple genomes has a number of implications for comparative, evolutionary and functional genomics as well as synthetic biology. RESULTS: In this paper we describe a new method for detecting conserved gene clusters that incorporates the information captured by a genome phylogenetic tree. We show that our method can overcome the common problem of overestimation of significance due to the bias in the genome database and thereby achieve better accuracy when detecting functionally connected gene clusters. Our results can be accessed at database GeneChords http://genomics10.bu.edu/GeneChords. CONCLUSION: The methodology described in this paper gives a scalable framework for discovering conserved gene clusters in microbial genomes. It serves as a platform for many other functional genomic analyses in microorganisms, such as operon prediction, regulatory site prediction, functional annotation of genes, evolutionary origin and development of gene clusters.

Algorithms↗
PubMed2006

RNase L: its biological roles and regulation.

2'-5'oligoadenylate-dependent ribonuclease L (RNase L) is one of the key enzymes involved in the function of interferons (IFNs), a family of cytokines participating in innate immunity against viruses and other microbial pathogens. Upon binding with its activator, 5'-phosphorylated, 2'-5' linked oligoadenylates (2-5A), RNase L degrades single-stranded viral and cellular RNAs and thus plays an important role in the antiviral and antiproliferative functions of IFNs. In recent years, evidence has revealed that RNase L displays a broad range of biological roles which are summarized in this review.

Animals↗
PubMed2026

Exploring the hypothetical role of Bacteroides species in depression progression: insights from metagenomic analysis.

Depression, a psychiatric disorder with significant morbidity and mortality, has a complex etiology. Recent advances in microbiome research have highlighted the potential role of fecal microbiota in depression pathogenesis. This study utilized shotgun metagenomic sequencing to compare the fecal microbiota of 28 depression patients and 26 healthy individuals. Significant differences in fecal microbiota composition were observed between the two groups. We generated 350 non-redundant high-quality metagenome-assembled genomes (MAGs) by binning and conducted comparisons between the depression and control groups. Notably, we found that the MAGs enriched in people with depression mostly belonged to Bacteroides, indicating a close link between Bacteroides abundance and the development of depression, suggesting that Bacteroides might be a potential culprit for depression. In the depression group, we found that the module of nitric oxide synthesis was remarkably enriched, and all Bacteroides MAGs contained genes annotated as nitric oxide synthase, suggesting that increased levels of Bacteroides may contribute to elevated nitric oxide synthesis. A distinct microbial signature consisting of Arthrobacter sp._U41, Bacillus cereus, Campylobacter rectus, and Pasteurella dagmatis accurately discriminates between depressed individuals and healthy controls, achieving an average area under the receiver operating characteristic curve of 0.950. This research sheds light on the potential role of fecal microbiota in depression and highlights specific metabolic pathways and microbial markers for further investigation.IMPORTANCEThis research highlighted significant differences in the composition and function of fecal microbiota between individuals with depression and healthy individuals, particularly the enrichment of Bacteroides metagenome-assembled genomes (MAGs) in depression patients. The upregulation of the nitric oxide synthesis pathway associated with these MAGs belonging to Bacteroides in the gut of depression patients had also been observed. The selected bacterial biomarkers reliably differentiate depression cases from healthy controls with high diagnostic accuracy (mean area under the receiver operating characteristic curve = 0.950). Our results suggest the importance of exploring microbial markers as potential diagnostic and therapeutic targets in managing depression.

Humans↗
PubMed2001

Pancreatic islet-cell viability, functionality and oxidative status remain unaffected at pharmacological concentrations of commonly used antibiotics in vitro.

Environmental factors such as diet, physical activity, drugs, pollution and life style play an important role in the progression and/or precipitation of diseases like diabetes, hypertension, obesity and cardiovascular disorders. Indiscriminate use of antibiotics to combat infectious diseases is one of the commonest forms of misuse of drugs. Antibiotics seem to have a correlation with diabetes and pancreatic function. There are controversial reports about the effect of antibiotics on the pancreatic islets; some suggesting their harmless action, some depicting a beneficial role and others indicating deleterious effect. Moreover, use of antibiotics is mandatory during islet isolation and cultivation to reduce incidences of microbial contamination. It is likely that antibiotic treatment may adversely affect islet viability and its functioning leading to failure of islet transplantation. The present in vitro study was undertaken to examine the effect of commonly used antibiotics such as gentamycin, penicillin, streptomycin, tetracycline, neomycin, erythromycin and chloramphenicol on islet viability, its functioning and induction of oxidative stress if any. The viability and insulin production data showed that none of the antibiotics used in the present study affect the viability and the functioning of the islets at their pharmacological concentrations. Free radical levels measured in terms of melonyldialdehyde (MDA), nitric oxide (NO) and reduced glutathione (GSH) reveal that except for a marginal increase in lipid peroxidation with tetracycline and slight increase in NO levels with streptomycin, none of these antibiotics affect the oxidative status of the cells. Antioxidant enzymes such as superoxide dismutase and catalase remain unaffected after this treatment. Our results reveal the innocuous nature of the antibiotics used at pharmacological concentrations, suggesting their safety whenever prescribed to combat infections and also during islet isolation procedures.

Animals↗
PubMed1995

Effects of IL-12 on immune responses to microbial infections: a key mediator in regulating disease outcome.

Recent studies have documented that the immunoregulatory functions of IL-12 may play a role in promoting endogenous protective responses during infections and/or contribute to pathology resulting from unregulated cytokine expression. Pathogen induction of IL-12 elicits interferon-gamma production by natural killer cells, which contributes to early defense during certain bacterial, parasitic, and viral infections. IL-12 also facilitates the development of T helper type 1 (Th1) lymphocytes required for late protection against bacteria, parasites, and fungi. During viral infections, however, there appear to be mechanisms independent of IL-12 for inducing protective T-cell responses. In contrast, negative regulation of IL-12 during acute infections can be a key event in the establishment of chronic infection and protection against harmful excessive cellular immune response. Under appropriate conditions, IL-12 has therapeutic efficacy for promoting defense against a variety of pathogens, and for use as a vaccine adjuvant to enhance beneficial Th1 over detrimental Th2 lymphocyte responses. This information extends knowledge about the regulation of immune responses to infectious agents, and provides new insights for the development of treatment and adjuvant strategies to potentiate beneficial or inhibit detrimental endogenous immune responses.

Animals↗
PubMed2005

Immune modulatory effects of Prunella vulgaris L.

Prunella vulgaris L. (Labiatae) is a perennial plant known as 'self-heal' in Western herbal medicine. It has a wide array of biological effects exhibiting numerous therapeutic potentials. Its anti-microbial effects including anti-viral and anti-bacterial effects are, presently, receiving increasing attention. While its anti-viral effects are attributed mainly to the inhibition of virus replication, the biological mechanisms of its anti-bacterial effects or actions remain unknown. In view of the fact that polysaccharides isolated from medicinal herbs often function as biological response modifier of body immunity, we hypothesized that the anti-microbial effect of polysaccharides isolated from P. vulgaris is probably also mediated via immune modulation. We have isolated four polysaccharides containing fractions from P. vulgaris, one of the fractions, PV2, could markedly stimulate the production of superoxide and nitrite representing nitric oxide from murine macrophage RAW264.7 and brain macrophage BV2 cells. The amount of nitrite and superoxide produced after PV2 stimulation was as high as that seen in stimulation using bacterial endotoxin lipopolysaccharide (LPS), and this stimulatory response is dose-dependent. In addition to monocyte/macrophage, PV2 also stimulated the proliferation of splenocytes. In this study, we have shown that the polysaccharides isolated from P. vulgaris have marked immune stimulatory effects, which may bring about the anti-microbial effects of P. vulgaris.

Animals↗