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PubMedDate not supplied

[Microorganisms distribution in the aerosol of a manned sealed cabin and the effect of artificial air ionization on this process].

In a manned enclosure the distribution of bacterial aerosol with respect to the size of particles is bimodal. Artificial bipolar ionization of the air may decrease the content of relatively large particles of bacterial aerosol, leaving particles with 2.0-0.6/micrometer in diameter in predominance. These properties of the bacterial aerosol structure may be of importance in the prophylaxis of aerogenic infections of cosmonauts.

Aerosols↗
PubMed1983

Characterization of the Rous sarcoma virus transforming gene product.

This report describes quantitative results of in vitro phosphorylation of the Rous sarcoma virus transforming gene product, pp60src, using ATP or GTP as phosphate donors. The Km values for the phosphorylation of pp60src by ATP and GTP were similar (10-36 and 25-36 microM, respectively) and the Vmax values were different (5-7 and 1.5-1.7 nmol min-1 mg-1 of pp60src, respectively). The radiolabeling of pp60src by [gamma-32P] ATP was inhibited by ADP and dATP at 20-fold higher concentrations by 75 and 83%, respectively. Other nucleotides served as weaker inhibitors under the same conditions. The radiolabeling of pp60src by [gamma-32P]GTP had lower specificity for this nucleotide, since ATP, dATP, ADP, dGTP, GDP, and TTP had at least a 50% inhibitory effect. The phosphorylated products of approximate Mr = 60,000 that were produced with ATP or GTP were shown to be the same protein molecule since they both could be immunoprecipitated with antibody raised against p60src produced by bacterial recombinants. Structural analysis revealed that the use of GTP resulted in phosphorylation of a tyrosine residue on the COOH-terminal region of pp60src, apparently the same site which contains the tyrosine phosphorylated in infected cells. In contrast, the use of ATP resulted in phosphorylation of several additional tyrosine residues on the NH2-terminal region of the molecule. In thermolability studies, the t1/2 values for the phosphorylation of pp66src in preparations from wild type virus-infected chicken cells were 5.1 min for both ATP and GTP, whereas the t1/2 values for the phosphorylation of pp60src in preparations from temperature-sensitive transformation mutant-infected cells were 1.1 min for both phosphate donors. Similar observations were found with alpha-casein as substrate.

Adenosine Triphosphate↗
PubMed1982

Epithelioid granuloma formation requiring no T-cell function.

Muramyl dipeptide (MDP), a minimal structure in bacterial cell walls essential for their adjuvant activity, was incorporated in a water-in-oil emulsion and injected into the footpads of nude rats devoid of functional T cells. MDP thus injected evoked massive epithelioid granulomas in the draining lymph nodes, indicating that MDP induced epithelioid granuloma formation requires no T cells. This finding with other data available strongly suggest that epithelioid granulomas can be induced without immunologic reactions.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMedDate not supplied

[Biological significance of nucleosomes in bacteria].

The paper presents data concerning the structural organization of specialized membrane structures in bacterial cells, viz. nucleoidosomes involved in DNA replication. A possible correlation between the number of homologous chromosomes in a nucleoid, the presence of nucleodosomes and their dimensions is discussed. Apparently, the role of nucleoidosomes is to increase the active surface of a plasmalemma region necessary to locate the replicative centers of circular DNA molecules in bacterial nucleoids.

Bacteria↗
PubMed1993

Urtica dioica agglutinin. A superantigenic lectin from stinging nettle rhizome.

Urtica dioica agglutinin (UDA) is an unusual plant lectin that differs from all other known plant lectins with respect to its molecular structure and its extremely low specific agglutination activity. We recently reported that this small lectin (8.5 kDa) is a T cell mitogen distinguishable from classical T cell lectin mitogens by its ability to discriminate a particular population of CD4+ and CD8+ T cells as well as its capacity to induce an original pattern of T cell activation and cytokine production. The mechanism by which UDA activates T cells was investigated and compared with the conventional T cell mitogen Con A and the known superantigen staphylococcal enterotoxin B. Our data show that T cell proliferation induced by UDA is strictly dependent on AC expressing MHC class II molecules but is not MHC restricted. This proliferation can be partially inhibited by anti-I-A or anti-I-E mAb and completely blocked by a mAb recognizing monomorphic determinants on the Ia molecule. UDA indeed binds to specific carbohydrate structures present on class II molecules. UDA-induced T cell stimulation is dependent on TCR recognition of the unprocessed intact molecule in association with various Ia molecules. T cell response to UDA is clonally expressed and correlates with particular TCR V beta gene families usage. This stimulation leads to a sixfold enrichment of V beta 8.3+ T cells within 3 days. Therefore, UDA appears to use the same molecular mechanism as structurally unrelated bacterial or retroviral superantigens and we propose that this lectin is a superantigen. UDA, which is not a pathogenicity factor, could provide a useful probe for the analysis of T cell activation by superantigens.

Animals↗
PubMed1993

[Structure of lipopolysaccharides from gram-negative bacteria. II. Core structure (Review)].

The review summarizes the data on the core structure of bacterial lipopolysaccharides (LPS) which represents an oligosaccharide binding the lipid moiety of the macromolecule to the O-antigenic polysaccharide chain. Both S-strains with complete LPS and R-mutants having various defects of the core biosynthesis are considered. The role of the core in the outer membrane functioning and manifestation of antigenic specificity of LPS is discussed.

Carbohydrate Conformation↗
PubMed1998

[Biochemical and immunological properties of the fractions of tubercle bacilli].

In 1954, Dr. Yuichi Yamamura and his coassociates, National Sanatorium Toneyama Hospital, has reported the formation of experimental tuberculous cavity in rabbits. This work was a milestone of the researches in the field of cellular immunology. In 1960, I have started my scientific carrier in Kyushu University Medical School as the post-graduate student under the guidance of Prof. Yamamura. Since then, I have worked on the field of biochemical and immunological properties of tubercle bacilli. The arabinose mycolate, polysaccharides, cell-wall skeleton (CWS) and trehalose dimycolate (TDM) were purified from tubercle bacilli and their Chemical structures and biological activities were investigated in detail in our laboratory. In 1971, we have reported that adjuvant active principle of tubercle bacilli was a CWS fraction, and the details of chemical structure and adjuvantity of mycobacterial CWS were investigated in our research group. The application of BCG-CWS to cancer immunotherapy was also studied. In 1974, Prof. E. Lederer and his coworkers, University of Paris, have reported that N-acetyl muramyl-L-alanyl-D-isoglutamine (MDP) was the minimum adjuvant-active structure of bacterial cell wall. We have synthesized several hundreds of MDP derivatives and selected, MDP-Lys(L18), romurtide, as the candidate of cytokine inducer for the clinical application. Romurtide is applied in cancer patients for the recovery of the number and functions of monocytes, neutrophils and platelets. These results suggest that the tubercle bacilli, especially, CWS and related synthetic MDP derivatives, are effective for the potentiation of host resistance against infectious diseases and cancer.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed2007

Structure, mechanism and physiological roles of bacterial cytochrome c peroxidases.

Cytochrome-c peroxidases (CCPs) are a widespread family of enzymes that catalyse the conversion of hydrogen peroxide (H2O2) to water using haem co-factors. CCPs are found in both eukaryotes and prokaryotes, but the enzymes in each group use a distinct mechanism for catalysis. Eukaryotic CCPs contain a single b-type haem co-factor. Conventional bacterial CCPs (bCCPs) are periplasmic enzymes that contain two covalently bound c-type haems. However, we have identified a sub-group of bCCPs by phylogenetic analysis that contains three haem-binding motifs. Although the structure and mechanism of several bacterial di-haem CCPs has been studied in detail and is well understood, the physiological role of these enzymes is often much less clear, especially in comparison to other peroxidatic enzymes such as catalase and alkyl-hydroperoxide reductase. In this review, the structure, mechanism and possible roles of bCCPs are examined in the context of their periplasmic location, the regulation of their synthesis by oxygen and their particular function in pathogens.

Amino Acid Sequence↗
PubMed1997

Characterization of the sediment bacterial community in groundwater discharge zones of an alkaline fen: a seasonal study.

The cell density, activity, and community structure of the bacterial community in wetland sediments were monitored over a 13-month period. The study was performed at Cedar Bog, an alkaline fen. The objective was to characterize the relationship between the sediment bacterial community in groundwater upwelling zones and the physical and chemical factors which might influence the community structure and activity. DNA, protein, and lipid synthesis were measured at three different upwelling zones by using [3H]thymidine, [14C]leucine, and [14C]glucose incorporation, respectively. The physiological status (apparent stress) of the consortium was assessed by comparing [14C]glucose incorporation into membrane and that into storage lipids. Bacterial cell density was determined by acridine orange direct counts, and gross bacterial community structure was determined by bisbenzimidazole-cesium chloride gradient analysis of total bacterial community DNA. Both seasonal and site-related covariation were observed in all estimates of bacterial biomass and activity. Growth rate estimates and cell density peaked in late July at 2.5 x 10(8) cells/g/day and 2.7 x 10(9) cells/g, respectively, and decreased in December to 2.0 x 10(7) cells/g/day and 1.5 x 10(9) cells/g, respectively. Across sites, membrane-to-storage-lipid ratios were generally highest in late spring and peaked in September for one site. Overall, the data indicate dynamic seasonal differences in sediment bacterial community activity and physiology, possibly in response to changing physical and chemical environmental factors which included the C/N/P ratios of the perfusing groundwater. By contrast, total cell numbers were rather constant, and community structure analysis indicated that the overall community structure was similar throughout the study.

Bacteria↗
PubMed1991

6-(substituted methylene)penems, potent broad spectrum inhibitors of bacterial beta-lactamase. III. Structure-activity relationships of the 5-membered heterocyclic derivatives.

Sodium (5RS)-Z-6-(heterocyclylmethylene)penem-3-carboxylates (2) are a series of extremely potent inhibitors of bacterial beta-lactamases. A variety of 5-membered heteroaromatic derivatives have been prepared and structure-activity studies reveal a preferred substituent orientation. One of these derivatives, the 1-methyl-1,2,3-triazolyl compound (5m) is a more potent synergist of amoxycillin than clavulanic acid, sulbactam or tazobactam.

Amoxicillin↗
PubMed2001

Photo-CIDNP 13C magic angle spinning NMR on bacterial reaction centres: exploring the electronic structure of the special pair and its surroundings.

Photochemically induced dynamic nuclear polarisation (photo-CIDNP) in intact bacterial reaction centres has been observed by 13C-solid state NMR under continuous illumination with white light. Strong intensity enhancement of 13C NMR signals of the aromatic rings allows probing the electronic ground state of the two BChl cofactors of the special pair at the molecular scale with atomic selectivity. Differences between the two BChl cofactors are discussed. Several aliphatic 13C atoms of cofactors, as well as 13C atoms of the imidazole ring of histidine residue(s), show nuclear-spin polarisation to the same extent as the aromatic nuclei of the cofactors. Mechanisms and applications of polarisation transfer are discussed.

Carbon Isotopes↗