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PubMedDate not supplied

[Changes in the structural function of the membrane of M. lysodeikticus as affected by preparations of the bacterial autoregulatory factors D1].

Introduction of factors D1 isolated from the culture fluids of B. cereus and Ps. carboxydoflava into cytoplasmic membranes of M. lysodeikticus resulted in a higher microviscosity of the lipid phase. Factor d1 changes the ion permeability of an artificial bilayer membrane as well as reduces the content of free water in the bacterial paste. It is assumed that registered structural changes may result from the interaction of the factor molecules with membrane lipids and be the main reason of changes in the functioning of membrane-bound enzymes and dehydration of the microbial cell as well.

Bacillus cereus↗
PubMed1993

[Experimental study on the interaction of fibronectin with oral Streptococci].

Interaction of fibronectin (Fn) with Streptococcus mutans, S. sorbrinus, and S. milleri is demonstrated by an enzyme-linked immunosorbent assay (ELISA). The results show that the three strains are able to adhere to Fn. The interaction may be strengthened while the concentration of Fn increases (q test P < 0.01). The ability of adherence among S. mutans, S. sorbrinus and S. milleri is different in Fn high concentration (q test P < 0.01). It is speculated the free Fn in saliva may serve as an agglution for elimination of the organisms from the oral cavity, or as a receptor when immobilized on the tooth surface for cariogenic streptococci to form plaque. A balance between these two functions of Fn may play a role in modulating the microbial ecological environment of the oral cavity.

Animals↗
PubMed1998

[Pathogenesis of pancreatogenic sepsis].

The intestinal tract is the motor of sepsis in the "gut-MOF hypothesis". Acute pancreatitis causes an early severe reduction of intestinal microcirculation with consequent production of radicals and cytokines damaging intestinal integrity. The intestinal organ dysfunction syndrome results in a breakdown of barrier function and a loss of propulsive activity. This leads to microbial overgrowth and bacterial translocation. This liberates cytokines and causes secondary pancreatic infection after lymphatic and systemic bacterial dissemination. Infected pancreatic necrosis by enteric microorganisms is the main cause of pancreatic sepsis.

Bacterial Translocation↗
PubMed2006

Therapeutic potential of chitosan and its derivatives in regenerative medicine.

BACKGROUND: Cell-based transplantation, tissue engineering and gene therapy are important therapeutic strategies for present and future regenerative medicine. One challenge is to present the target cells in a suitable matrix to allow the cells to survive the wound contraction, tissue repair, and remodeling in certain tissues. Recently, functional biomaterial research has been directed towards the development of improved scaffolds and new drug delivery systems for regenerative medicine. MATERIALS AND METHODS: A literature survey was performed in basic and clinic publications relevant to the therapeutic potential of chitosan and its derivatives in regenerative medicine. In this review the functional properties and potential applications of chitosan and its derivatives in regenerative medicine are presented and discussed. RESULTS: Chitosan can be obtained by alkaline deacetylation of chitin and is found to be a natural-based nontoxic, biocompatible, and biodegradable polymer with anti-microbial activity. Chitosan and its derivatives could accelerate wound healing by enhancing the functions of inflammatory cells and repairing cells. Recent studies further indicated that chitosan and its derivatives also are novel scaffold materials for tissue engineering and are-promising non-viral vectors for gene delivery. CONCLUSIONS: Regenerative medicine has entered a new era with the development of modern science and technology. The novel properties of chitosan make it a versatile biomaterial for cell therapy, tissue engineering and gene therapy. It is hoped that these diverse approaches for regenerative medicine will translate from "bench to bedside" in the future.

Animals↗
PubMed2000

Regulation of the adhesion versus cytotoxic functions of the Mac-1/CR3/alphaMbeta2-integrin glycoprotein.

Mac-1/CR3 functions as both an adhesion molecule mediating the diapedesis of leukocytes across the endothelium and a receptor for the iC3b fragment of complement responsible for phagocytic/degranulation responses to microorganisms. Mac-1/CR3 has many functional characteristics shared with other integrins, including bidirectional signaling via conformational changes that originate in either the cytoplasmic domain or extracellular region. Another key to its functions is its ability to form membrane complexes with glycosylphosphatidylinositol (GPI)-anchored receptors such as Fc gammaRIIIB (CD16b) or uPAR (CD87), providing a transmembrane signaling mechanism for these outer membrane bound receptors that allows them to mediate cytoskeleton-dependent adhesion or phagocytosis and degranulation. Many functions appear to depend upon a membrane-proximal lectin site responsible for recognition of either microbial surface polysaccharides or GPI-linked signaling partners. Because of the importance of Mac-1/CR3 in promoting neutrophil inflammatory responses, therapeutic strategies to antagonize its functions have shown promise in treating both autoimmune diseases and ischemia/reperfusion injury. Conversely, soluble beta-glucan polysaccharides that bind to its lectin site prime the Mac-1/CR3 of circulating phagocytes and natural killer (NK) cells, permitting cytotoxic degranulation in response to iC3b-opsonized tumor cells that otherwise escape from this mechanism of cell-mediated cytotoxicity.

Antibodies, Monoclonal↗
PubMed2005

Azospirillum brasilense does not affect population structure of specific rhizobacterial communities of inoculated maize (Zea mays).

Positive response of plant species to plant growth-promoting rhizobacteria have led to an increased interest in their use as bacterial inoculants. However, the introduction of exogenous bacteria into natural ecosystems may perturb bacterial populations within the microbial community and lead to the disruption of indigenous populations performing key functional roles. In this study the effect of Azospirillum brasilense inoculation on maize (Zea mays) rhizosphere Actinobacteria, Bacteroidetes, alpha-Proteobacteria, Pseudomonas and Bdellovibrio spp. was assessed using a polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) approach in conjunction with group-specific primers. The DGGE fingerprints analysis revealed that the introduction of A. brasilense did not alter or disrupt the microbial system at the group-specific level. However, some communities such as the alpha-Proteobacteria and Bdellovibrio were influenced by plant age while the other bacterial groups remained unaffected. Based on these as well as previous data, it can be inferred that inoculation with A. brasilense does not perturb the natural bacterial populations investigated.

Azospirillum brasilense↗
PubMed2002

Constitutive expression of a single antimicrobial peptide can restore wild-type resistance to infection in immunodeficient Drosophila mutants.

One of the characteristics of the host defense of insects is the rapid synthesis of a variety of potent antibacterial and antifungal peptides. To date, seven types of inducible antimicrobial peptides (AMPs) have been characterized in Drosophila. The importance of these peptides in host defense is supported by the observation that flies deficient for the Toll or Immune deficiency (Imd) pathway, which affects AMP gene expression, are extremely susceptible to microbial infection. Here we have developed a genetic approach to address the functional relevance of a defined antifungal or antibacterial peptide in the host defense of Drosophila adults. We have expressed AMP genes via the control of the UAS/GAL4 system in imd; spätzle double mutants that do not express any known endogenous AMP gene. Our results clearly show that constitutive expression of a single peptide in some cases is sufficient to rescue imd; spätzle susceptibility to microbial infection, highlighting the important role of AMPs in Drosophila adult host defense.

Animals↗
PubMed2026

Isolation and genomic characterization of Bacillus X32: a potent phosphate-solubilizing bacterium with growth-promoting effects on navel orange seedlings.

Phosphorus is an essential element for plant growth. However, in nature, most phosphorus exists in the form of insoluble compounds that plants cannot directly absorb, leading to phosphorus deficiency in agricultural systems. With increasing demand for economic crops such as citrus and the decline in soil fertility due to current management practices, there is a growing need for environmentally friendly fertilizers to improve and restore soil conditions. In this study, a highly efficient phosphate&#x2011;solubilizing strain X32 was isolated from the rhizosphere soil of Gannan navel oranges. Systematic genomic analysis identified it as a putative novel species within the genus Bacillus, showing the closest phylogenetic relationship to Bacillus spizizenii. However, both the average nucleotide identity (ANI&#x2009;=&#x2009;93.18%) and digital DNA&#x2011;DNA hybridization (dDDH&#x2009;=&#x2009;50.4%) values fell below the established thresholds for species delineation, indicating significant genomic differentiation. Whole&#x2011;genome sequencing further revealed that strain X32 harbors multiple functional genes potentially related to phosphorus metabolism, including inorganic phosphate&#x2011;solubilizing genes (e.g., gdh and gltA), phosphate transport genes (e.g., glpT, pstA, pstB, pstC), and phosphorus mineralization genes (e.g., phoA, phoD). Pot experiment results demonstrated that inoculation with strain X32 significantly promoted the growth of navel orange seedlings, as evidenced by marked increases in both aboveground and belowground fresh and dry weights, as well as plant height. Additionally, strain X32 significantly enhanced the activities of antioxidant enzymes (SOD, CAT, POD) and regulated the content of chlorophyll b in seedling leaves, these changes suggest that strain X32 may enhance stress resistance in plants and influence photosynthetic pigment composition, though direct measurements of photosynthetic performance are needed for confirmation. This study provides a theoretical basis for developing microbial fertilizers with efficient phosphorus solubilization and plant growth-promoting functions, which may help reduce dependence on phosphorus fertilizers and promote sustainable agricultural development.

Phosphates↗
PubMed2002

Association of microbial community composition and activity with lead, chromium, and hydrocarbon contamination.

Microbial community composition and activity were characterized in soil contaminated with lead (Pb), chromium (Cr), and hydrocarbons. Contaminant levels were very heterogeneous and ranged from 50 to 16,700 mg of total petroleum hydrocarbons (TPH) kg of soil(-1), 3 to 3,300 mg of total Cr kg of soil(-1), and 1 to 17,100 mg of Pb kg of soil(-1). Microbial community compositions were estimated from the patterns of phospholipid fatty acids (PLFA); these were considerably different among the 14 soil samples. Statistical analyses suggested that the variation in PLFA was more correlated with soil hydrocarbons than with the levels of Cr and Pb. The metal sensitivity of the microbial community was determined by extracting bacteria from soil and measuring [(3)H]leucine incorporation as a function of metal concentration. Six soil samples collected in the spring of 1999 had IC(50) values (the heavy metal concentrations giving 50% reduction of microbial activity) of approximately 2.5 mM for CrO(4)2- and 0.01 mM for Pb2+. Much higher levels of Pb were required to inhibit [14C]glucose mineralization directly in soils. In microcosm experiments with these samples, microbial biomass and the ratio of microbial biomass to soil organic C were not correlated with the concentrations of hydrocarbons and heavy metals. However, microbial C respiration in samples with a higher level of hydrocarbons differed from the other soils no matter whether complex organic C (alfalfa) was added or not. The ratios of microbial C respiration to microbial biomass differed significantly among the soil samples (P < 0.05) and were relatively high in soils contaminated with hydrocarbons or heavy metals. Our results suggest that the soil microbial community was predominantly affected by hydrocarbons.

Bacteria↗
PubMed2006

Induction of multiple prophages from a marine bacterium: a genomic approach.

Approximately 70% of sequenced bacterial genomes contain prophage-like structures, yet little effort has been made to use this information to determine the functions of these elements. The recent genomic sequencing of the marine bacterium Silicibacter sp. strain TM1040 revealed five prophage-like elements in its genome. The genomes of these prophages (named prophages 1 to 5) are approximately 74, 30, 39, 36, and 15 kb long, respectively. To understand the function of these prophages, cultures of TM1040 were treated with mitomycin C to induce the production of viral particles. A significant increase in viral counts and a decrease in bacterial counts when treated with mitomycin C suggested that prophages were induced from TM1040. Transmission electron microscopy revealed one dominant type of siphovirus, while pulsed-field gel electrophoresis demonstrated two major DNA bands, equivalent to 35 and 75 kb, in the lysate. PCR amplification with primer sets specific to each prophage detected the presence of prophages 1, 3, and 4 in the viral lysate, suggesting that these prophages are inducible, but not necessarily to the same level, while prophages 2 and 5 are likely defective or non-mitomycin C-inducible phages. The combination of traditional phage assays and modern microbial genomics provides a quick and efficient way to investigate the functions and inducibility of prophages, particularly for a host harboring multiple prophages with similar sizes and morphological features.

Bacteriophages↗
PubMed1980

Immunologic function in patients with carcinoma of the pancreas.

The immune fuction of 41 patients with duct cell adenocarcinoma of the pancreas or carcinoma of the periampullary region was studied by skin testing with 2,4-dinitrocholorobenzene and common microbial antigens, in vitro lymphocyte reactivity to mitogens, T-lymphocyte and B-lymphocyte cell counts and measurements of complement levels. Results show that a great proportion of patients had depressed immune function. Depression is particularly severe in lymphocyte reactivity. Positive response to skin tests with a microbial antigen carries a slightly better prognosis. The complement level is usually normal or elevated. Correlation between immune function, prognosis and tumor resectability in individual patients is generally poor.

Adenocarcinoma↗
PubMed2003

Validation of a more sensitive method for using spotted oligonucleotide DNA microarrays for functional genomics studies on bacterial communities.

Spotted oligonucleotide microarrays potentially offer a wide scope of applications for microbial ecology, especially as they improve the flexibility of design and the specificity of detection compared to PCR product based microarrays. Sensitivity, however, was expected to be problematic, as studies with the more sensitive PCR-based cDNA microarrays indicate that only genes from populations contributing to more than 5% of the community DNA can be detected. We evaluated several parameters to increase sensitivity and then tested applicability for bacterial functional genomics. The optimal parameters were the use of 5'-C6-amino-modified 70-mers printed on CMT-GAPS II substrates at a 40 micro M concentration combined with the use of Tyramide Signal Amplification labelling. This protocol allowed detection of single copy genes belonging to an organism contributing to 1% or more of the total community. To demonstrate its application, we detected the specific aromatic oxygenase genes in a soil community degrading polychlorinated biphenyls (PCBs). This increase in sensitivity is important if oligonucleotide microarrays are to be used for simultaneous monitoring of a range of functions performed by different microorganisms in the environment.

Bacteria↗
PubMed2006

Immune interactions with CD4+ T cells promote the development of functional osteoclasts from murine CD11c+ dendritic cells.

Dendritic cells (DC) are innate immune effectors and are critically involved in regulating T cell immunity. Osteoclasts (OC) are bone-resorbing cells derived from the monocyte/macrophage lineage in response to receptor activator of NF-kappaB ligand (RANKL). DC and T cells form aggregates in the inflammatory infiltrates at active disease sites in human and in experimental rheumatoid arthritis and periodontitis. We investigated whether DC interactions with T cells in the bone environment can support the development of functional OC. In the present study, we demonstrate that upon proper activation by microbial or protein Ags (namely Actinobacillus actinomycetemcomitans, bovine insulin, and outer membrane protein-1) and during immune interactions with CD4+ T cells in vitro, murine BM-derived and splenic CD11c+ DC (CD11b- F4/80- Ly-6C- CD31-) develop into TRAP+ CT-R+ cathepsin-k+ functional OC in a RANKL/RANK-dependent manner. Rescue and blocking experiments using CD11c+ DC derived from Csf-1(-/-) op/op mice show that M-CSF is required "before" developing such osteoclastogenic potential upstream of RANKL/RANK signaling, suggesting that immature CD11c+ DC can indeed act like OC precursors. In addition, these CD11c+ DC-derived OC are capable of inducing bone loss after adoptive transfer in vivo. These data suggest a direct contribution of DC during immune interactions with CD4+ T cells to inflammation-induced osteoclastogenesis. Therefore, our findings not only provide further evidence for DC plasticity, but also extend the current paradigm of osteoimmunology.

Acid Phosphatase↗
PubMed2006

Is there a role of food allergy in irritable bowel syndrome and functional dyspepsia? A systematic review.

A significant proportion of adults believe they suffer from food allergy, and 20-65% of patients with irritable bowel syndrome (IBS) attribute their symptoms to something in food that activates an abnormal response. This systematic review evaluates the role of food allergy in aetiology and management of these disorders. Activation of gastrointestinal mucosal immune system may be one of the causative factors in the pathogenesis of functional dyspepsia and IBS. This activation may result from effects of bacterial infection or other luminal factors including commensal microbial flora and food antigens. Some studies have reported on the role of food allergy in IBS; only one epidemiological study on functional dyspepsia and food allergy has been published. The mechanism by which food activates mucosal immune system is uncertain, but food specific IgE and IgG4 appeared to mediate the hypersensitivity reaction in a subgroup of IBS patients. Exclusion diets based on skin prick test, RAST for IgE or IgG4, hypoallergic diet and clinical trials with oral disodium cromoglycate have been conducted, and some success has been reported in a subset of IBS patients. Further well-controlled studies are needed to establish whether food allergy plays a role in the pathophysiology of functional dyspepsia and IBS.

Adult↗
PubMed1983

[Threshold doses of Staphylococcus aureus and the dynamics of leukocyte phagocytic activity in relation to the concentration of the causative agent in the blood].

The study of the phagocytic characteristics of leukocytes at different concentrations of Staphylococcus aureus, carried out in 18 persons, has revealed that the mechanism of phagocytosis cannot be triggered only by the presence of the infective agent in the blood; to trigger this mechanism, the concentration of the infective agent in the blood must reach a definite liminal level (for S. aureus this level is 0.5 X 10(6) microbial bodies per ml). A further rise in the concentration of the infective agent leads to the increase of the efficiency of phagocytosis as indicated by a curve resembling the exponential logarithmic function. When the concentration of S. aureus in the blood exceeds 1 X 10(9) microbial bodies per ml, no essential effect on the increase of phagocytic characteristics is observed.

Adult↗
PubMed2006

[Diversity and function of symbiotic microbes in the gut of lower termites].

The gut of lower termites harbor a complex microbial community, including eukaryotic flagellates and prokaryotic bacteria and archaea, which play important roles in the wood-cellulose digestion of these termites. The hindguts of lower termites are characterized with an enlarged paunch with steep oxygen and hydrogen gradient and not randomly distributed abundant microorganisms. The symbiotic flagellates in the gut of lower termites, which are normally associated with epibionts or endobionts, are phylogenetically affiliated with Trichomonadida, Hypermastigida and Oxymonadida. They endocytose wood particles and ferment the polysaccharide components to acetate, CO2 and H2, which are further metabolized by symbiotic prokaryotes as energy and nutrition sources in the termites. Cellulose genes such as glycosyl hydrolase family 45 have been identified in gut protists with molecular approach. Phylogenetic analysis have revealed that in the gut of lower termites, such as several Reticulitermites species, most of the dominant bacteria belong to phyla like "Termite group 1", Spirochaetes, Firmicutes, Bacteroidetes, and Proteobacteria. These bacteria clones normally form distinct termite clusters in phylogenetic trees, which show the existence of specific microbial diversity in the termite guts. Most of the symbiotic archaea in the gut of lower termites are methanogens and affiliated with the genus Methanobrevibacter by phylogenetic analysis and pure culture. The symbiotic bacteria and archaea may involve in the reduction of CO2 and the metabolism of N2 in these termite guts. However, the functions and metabolic mechanisms of the symbiotic flagellates and prokaryotes in the gut of lower termites are still remaining to be further elucidated.

Animals↗