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PubMedDate not supplied

Elevation of meal-stimulated gastrin release in subjects with Helicobacter pylori infection: reversal by low intragastric pH.

The aim of the present study was to determine whether the association between Helicobacter pylori infection and increased concentrations of gastrin in serum is independent of chronic duodenal ulcer disease and whether the mechanism of this association involves a disturbance of feedback inhibition of gastrin release by intragastric acid. Of 48 subjects evaluated, 26 (54%) were seropositive for H. pylori by ELISA. Fasting and peptone meal-stimulated gastrin release at pH 2.5 and pH 5.5 as well as integrated 24-hour plasma gastrin concentrations were significantly higher in the seropositive group, even when subjects with a history of duodenal ulcer were excluded. The inhibitory effect of low pH on the release of gastrin was not attenuated in subjects with positive results in the ELISA. These data indicate that the association between seropositivity for H. pylori and enhanced release of gastrin is independent of a history of duodenal ulcer and is not caused by a disturbance of the normal feedback inhibition of gastrin release by intragastric acid.

Adult↗
PubMed1976

Promotion of tumor growth in vivo by antimacrophage agents.

Various attempts were made to assess the role of the mononuclear phagocyte system in tumor resistance of rats in vivo. The growth of sc inoculated, weakly immunogenic, carcinogen-induced, syngeneic tumor cells was modestly reduced by ip injection and, more impressively, by local injection of peptone-induced, activated, nonimmune macrophages. A single iv injection of silica particles or carrageenan on the day of sc tumor cell inoculation greatly enhanced tumor growth. When these agents had been given a few days before or after tumor cell inoculation, the tumor-promoting efficiency was distintly diminished or even cancelled. The enhancing effects of silica and carrageenan on tumor growth were nulified by the macrophage-stabilizing agent, poly-2-vinylpyridine N-oxide, To assess the in vivo consequences of silica administration, various cellular, biochemical, and functional macrophage parameters were determined at different intervals. Results indicated the complexity of events elicited after the mononuclear phagoycte system was damaged, which made the interpretation of such results difficult.

Animals↗
PubMed2000

Validation of thiosulfate for neutralization of acidified sodium chlorite in microbiological testing.

At low pH, acidified sodium chlorite (ASC) has antimicrobial activity against a variety of foodborne contaminants. To evaluate the antimicrobial efficacy of ASC at specific time points posttreatment, it is necessary to halt the action of the disinfectant by removing residual chlorite or by increasing the pH. In this study, thiosulfate was investigated at varying concentrations for its effect on microbial survival and was investigated at a concentration of 0.1% in the presence of ASC for its effect on the antimicrobial and chemical activity of the test solution. Additionally, sodium thiosulfate was tested in two buffering systems, buffered peptone water (BPW) and Butterfield's phopshate buffer (BPB), for its ability to inactivate ASC chemistry. The results of this study show that, at a concentration of 0.1%, sodium thiosulfate has no deleterious effect on Escherichia coli survival and is effective in halting the antimicrobial action of ASC by eliminating the production of residual chlorite. The BPW alone and BPB in combination with thiosulfate were found to be effective inactivators of ASC chemistry.

Bacteria↗
PubMed1981

Regulation of extracellular alkaline protease activity by histidine in a collagenolytic Vibrio alginolyticus strain.

Vibrio alginolyticus synthesized an inducible extracellular collagenase in a peptone medium during the stationary growth phase. These cultures also possessed extracellular alkaline serine protease activity. The alkaline protease activity did not require a specific inducer and it was produced in tryptone or minimal media. The collagenase was not produced in either the tryptone or minimal media. The alkaline protease activity was sensitive to catabolite repression by a number of carbon sources, including glucose, and by amino acids and ammonium ions. Cyclic AMP, dibutyryl cyclic AMP and cyclic GMP did not relieve catabolite repression. Histidine and urocanic acid stimulated the production of alkaline protease activity in tryptone and minimal media. Other compounds associated with the histidine utilization (hut) pathway did not increase alkaline protease activity. Histidine reversed the repression of alkaline protease activity by glucose of (NH4)2SO4 in minimal medium. Histidine and the compounds associated with the hut pathway inhibited collagenase production.

Amino Acids↗
PubMed1981

Relationship between sporulation medium and germination ability of Mucor racemosus sporangiospores.

Asexual sporangiospores of Mucor racemosus produced on a minimal sporulation medium (M spores) germinated only if glucose, mannose or a complex substrate such as peptone, yeast extract or Casamino acids was present. Once germinated, growth was supported by a wide range of substrates including amino acids, carbohydrates or organic acids. Sporangiospores produced on a nutritionally complex sporulation medium (C-spores) germinated on a wide range of carbon sources. C-spore phenotype was pleiotropic in that sporangiospores capable of germinating on cellobiose could always germinate on glutamate or xylose; but C-spores capable of germinating on xylose or glutamate did not always germinate on cellobiose. There was a hierarchy of substrates capable of initiating germination with glucose = mannose greater than xylose greater than glutamate greater than cellobiose. C-spores also differed from M-spores by initiating germination in the presence of the non-metabolizable glucose analogue 3-O-methylglucose. These results suggest that at least two sporangiospore phenotypes are produced depending upon the concentration and type of ingredients present in the sporulation medium.

3-O-Methylglucose↗
PubMed1990

Internalization of lucifer yellow in Candida albicans by fluid phase endocytosis.

Lucifer yellow (LY), an impermeable fluorescent dye used as a marker for fluid phase endocytosis, was internalized by Candida albicans. As observed by fluorescence microscopy, incubation of C. albicans with LY in potassium phosphate buffer (pH 6.0) and glucose (2%, w/v) resulted in localization of the dye inside vacuoles. Sodium azide and carbonyl cyanide m-chlorophenylhydrazone, which are inhibitors of energy metabolism, decreased the uptake of the dye. The optimum temperature for uptake was 30 degrees C; no internalization was observed at 0 degrees C. Quantification of cell-associated LY by fluorescence spectrometry showed an uptake linear with time and not saturable over a 400-fold range of concentration. Thus, C. albicans internalized LY into vacuoles by a nonsaturable and time-, temperature- and energy-dependent process consistent with fluid phase endocytosis. Both the yeast and mould phase of this dimorphic fungus endocytosed LY. Growth in complex medium appeared to be required to enable the cells to internalize LY. However, addition of peptone or yeast extract to the phosphate buffer/glucose assay medium interfered with LY uptake by causing an apparent increase of exocytosis. These studies provide the first evidence of fluid phase endocytosis in C. albicans and may explain how some large molecules, such as toxins and cationic proteins, enter C. albicans.

Candida albicans↗
PubMed1991

Induction of secretory acid proteinase in Candida albicans.

Candida albicans and some other pathogenic Candida species, when grown in a medium containing a protein as a sole source of nitrogen, secrete an acid proteinase. Culture supernatants were assayed for proteinase activity, and were also analysed by Western blotting with antibodies raised and affinity-purified against proteinase of C. albicans. Proteinases secreted by C. tropicalis and C. parapsilosis were antigenically related to that of C. albicans, but had different molecular masses. The proteinases secreted by C. lipolytica, C. rugosa and C. lusitaniae were not antigenically related. The kinetics of proteinase secretion by C. albicans were monitored by activity and by Western blotting. With BSA as the nitrogen source, proteinase secretion increased exponentially until about 16 h. Culture supernatants of BSA-grown cultures accumulated proteinase to about a 1000-fold higher level than those of ammonium-sulphate-grown cultures. In vivo labelling experiments showed that proteinase was not detectably accumulated in the cells, but was secreted immediately after synthesis. Immunoprecipitation of in vitro translated poly(A)-containing RNA identified a putative pre-protein of about 54 kDa. As well as BSA, other proteins (haemoglobin, ovalbumin, histone), peptone and tryptone, when used as nitrogen sources, could induce proteinase, but to different levels. When Casamino acids or an amino acid mixture (equivalent to the composition of BSA) was used as nitrogen source, no induction was observed. Ammonium sulphate, or any other ammonium salt, repressed secretion of proteinase.

Amino Acids↗
PubMed1975

Determination of some in vitro growth requirements of Bacteroides nodosus.

Physical and nutritional factors required for growth of Bacteroides nodosus isolates from ovine foot-rot lesions were examined. Simplified anaerobic culture techniques were devised utilizing a fully soluble, autoclavable, liquid medium (TAS) which contained proteose-peptone, yeast and meat extracts and certain other essential compounds required to promote prompt and serially transferrable growth of cultures from small inocula. The latter included Trypticase, arginine, a reducing agent (most suitably thioglycollic acid) and CO2; serine and Mg2+ markedly increased growth yields. Trypticase could not be replaced by a commercial preparation of acid-hydrolysed casein; other forms of hydrolysed protein gave delayed and inconsistent growth. Maximum growth of cultures required concentrations of 0-02 to 0-35 M-arginine, which could not be replaced by glutamic acid, citrulline or ornithine. Exogenous carbohydrate compounds were not required. The temperature range for optimum growth of cultures was 37 to 39 degrees C, and anaerobic culture conditions were essential for growth and the production of B. nodosus organisms of normal morphology. Solidified TAS media for the isolation and maintenance of B. nodosus cultures were also devised.

Anaerobiosis↗
PubMed1999

Functional analysis of upstream regulating regions from the Yarrowia lipolytica XPR2 promoter.

The XPR2 gene from Yarrowia lipolytica encodes an inducible alkaline extracellular protease. Its complex regulation involves pH, carbon, nitrogen and peptones. Two previously identified upstream activating sequence (UAS) regions were analysed in a reporter system, outside the XPR2 context. Fragments from the UAS regions were inserted upstream of a minimal LEU2 promoter directing the expression of a reporter gene. The activity of the hybrid promoters was assessed following integration into the Y. lipolytica genome. This study confirmed the presence of two UASs composed of several interacting elements. Within the distal UAS (UAS1), a TUF/RAP1 binding site exhibited a UAS activity, which was enhanced by the presence of two adjacent repeats, overlapping sites similar to the CAR1 upstream repressing sequence from Saccharomyces cerevisiae. Within the proximal UAS (UAS2), the UAS activity required the interaction of both an ABF1-like binding site and a decameric repeat, containing Aspergillus nidulans PacC site consensus sequences. This decameric repeat was able to mediate repression due to carbon and/or nitrogen sources as well as pH-dependent activation. A study in the context of trans-regulatory mutations in the Y. lipolytica RIM101 gene showed that the PacC-like sites, potential binding sites for YlRim101p, were implicated in the derepression of UAS2-driven expression at neutral-alkaline pH. The in vivo response of the PacC-like decamers to external pH was dependent on the status of the pH-regulated activator YlRim101p, which is homologous to the A. nidulans PacC regulator. The carbon/nitrogen regulation imposed on the decamers was shown to be independent of YlRim101p and to override its effects.

3-Isopropylmalate Dehydrogenase↗
PubMed2006

Ignisphaera aggregans gen. nov., sp. nov., a novel hyperthermophilic crenarchaeote isolated from hot springs in Rotorua and Tokaanu, New Zealand.

Consortia containing a novel coccus-shaped, anaerobic heterotroph together with Pyrobaculum rods were cultivated from geothermal environments in New Zealand. Pure cultures of the cocci were only obtained from one such consortium, despite extensive attempts. Cells of this strain (AQ1.S1T) were regular to irregular cocci in morphology and occasionally formed large aggregates, especially when utilizing polysaccharides such as konjac glucomannan as a carbon source. Strain AQ1.S1T is a hyperthermophile, with an optimal temperature for growth between 92 and 95 degrees C (range 85-98 degrees C), and a moderate acidophile, with optimal growth occurring at pH 6.4 (range 5.4-7.0). Growth was inhibited by the addition of sulphur and NaCl (optimal growth occurred without addition of NaCl) and an electron acceptor was not required. Strain AQ1.S1T utilized starch, trypticase peptone, lactose, glucose, konjac glucomannan, mannose, galactose, maltose, glycogen and beta-cyclodextrin as carbon sources. The G+C content was 52.9 mol%. Based on 16S rRNA gene sequence analysis and physiological features it is proposed that isolate AQ1.S1T (=DSM 17230T=JCM 13409T) represents the type strain of a novel species of a new genus within the Crenarchaeota, Ignisphaera aggregans gen. nov., sp. nov.

Base Composition↗
PubMed2006

Reclassification of the sulfate- and nitrate-reducing bacterium Desulfovibrio vulgaris subsp. oxamicus as Desulfovibrio oxamicus sp. nov., comb. nov.

Desulfovibrio vulgaris subsp. oxamicus (type strain, DSM 1925(T)) was found to use nitrate as a terminal electron acceptor, the latter being reduced to ammonium. Phylogenetic studies indicated that strain DSM 1925(T) was distantly related to the type strain of Desulfovibrio vulgaris (95.4 % similarity of the small-subunit rRNA gene) and had as its closest phylogenetic relatives two other nitrate- and sulfate-reducing bacteria, namely Desulfovibrio termitidis (99.4 % similarity) and Desulfovibrio longreachensis (98.4 % similarity). Additional experiments were conducted to characterize better strain DSM 1925(T). This strain incompletely oxidized lactate and ethanol to acetate. It also oxidized butanol, pyruvate and citrate, but not glucose, fructose, acetate, propionate, butyrate, methanol, glycerol or peptone. The optimum temperature for growth was 37 degrees C (range 16-50 degrees C) and the optimum NaCl concentration for growth was 0.1 % (range 0-5 %). Because of significant genotypic and phenotypic differences from Desulfovibrio termitidis and Desulfovibrio longreachensis, reclassification of Desulfovibrio vulgaris subsp. oxamicus as Desulfovibrio oxamicus sp. nov., comb. nov., is proposed. The type strain is strain Monticello 2(T) (=DSM 1925(T)=NCIMB 9442(T)=ATCC 33405(T)).

Carbohydrate Metabolism↗
PubMed1986

Interaction of transferrin with iron-loaded rat peritoneal macrophages.

Rat peritoneal macrophages are capable, in vitro, of processing and releasing iron derived from phagocytosed, immunosensitized red cells. From 20% to 60% of the red cell iron can be returned to the culture medium in 24 h, with resident macrophages more active than inflammatory, peptone-induced macrophages. When apotransferrin is present in the culture medium, from 39% to 72% of iron released from macrophages is bound to the protein, with most of the remainder in a ferritin-like form. No distinct preference of released iron for either site of transferrin could be observed. The absence of apotransferrin depresses iron release only slightly, with much of the iron then released in a form readily available to the protein in vitro. Pronase treatment of macrophages, which abolishes their ability to bind transferrin, depresses iron release no more than 10-15%. It appears, therefore, that binding of apotransferrin to macrophages may not be essential for iron excretion by the cells.

Animals↗
PubMed1993

Antimicrobial effect of chlorine on Yersinia enterocolitica.

The effects of chlorine at varying pH, culture media and incubation temperatures on one type and two wild type strains of Yersinia enterocolitica were studied. Exposure to 1 and 5 mg 1(-1) did not diminish viability, even after prolonged exposure. A level of 10 mg 1(-1) was required to achieve a 5-log reduction in 120 s for the type strain and 80 s for the wild strains. There was an increase of more than 30% in the rate of disinfection with a 10 degrees C rise, a remarkable increase in antimicrobial activity at pH 5-log reduction in 20 s, as well as marked neutralization of the effect in the presence of 0.1% peptone. Younger cells were more susceptible than older ones, and those from liquid medium more resistant than those from solid medium. Incubation temperature of a 24-h inoculum failed to show any influence. Lastly, there was a noteworthy demand for free chlorine by bacterial biomass, with agreement of the curve depicting the drop in free chlorine in the presence of inoculum with biphasic kinetics of survival curves.

Cell Survival↗
PubMed1994

Effect of substrate on the production of antifungal volatiles from Bacillus subtilis.

An antibiotic-producing strain of Bacillus subtilis has been shown to produce potent antifungal volatiles (AFV). These volatiles are active against a range of fungal species and are produced on a range of growth media and in loam-based compost. In vitro antifungal volatile activity on nutrient agar is enhanced with the addition of D-glucose, complex carbohydrates and peptones. The addition of L-glucose led to significantly less AFV activity than comparable levels of D-glucose. Growth studies in liquid culture revealed that B. subtilis failed to grow in response to L-glucose. Further growth studies on solid media showed no clear correlation between enhanced bacterial growth and increases in in vitro AFV activity in response to supply of substrates. Low level AFV activity was also detected from oilseed rape roots inoculated with B. subtilis. Gas chromatography mass spectrometry headspace analysis of B. subtilis cultures grown on various substrates revealed common similarities between substrates promoting AFV activity, although it was not possible to isolate individual antifungal compounds.

Antifungal Agents↗
PubMed1979

Use of a macrophage cytotoxicity system to show macrophage activation by Listeria monocytogenes cell wall fraction.

Experiments were conducted to determine whether a partially purified listeria cell wall fraction could stimulate macrophages to high levels of activation. To detect activation of macrophages, a macrophage-mediated cytotoxicity system were established. The data demonstrate that listeria cell wall components are capable of activating thioglycollate-induced adherent peritoneal exudate cells to be cytotoxic for 51Cr-labelled target tumour cells, and that the listeria fraction is as effective as bacterial lipopolysaccharide in inducing cytotoxicity. The listeria fraction can also induce peritoneal exudate cells from congenitally thymusless nude mice to become cytotoxic, suggesting that mature T cells are not required. Furthermore, thioglycollate-induced adherent peritoneal exudate cells from mice hyperimmunized to live Listeria organisms are already stimulated to be cytotoxic for tumour cells, and do not need to be activated in vitro. Additional data are presented which characterize the system. These data demonstrate that a critical concentration of adherent peritoneal cells is required for in vitro activation. Moreover, only peritoneal cells induced with aged batches of thioglycollate, and not uniduced peritoneal cells or those induced with fresh thioglycollate or with protease peptone can be activated in vitro to kill tumour cells. Evidence is presented which suggests that the cytotoxic cell is a macrophage.

Animals↗
PubMed1990

In vitro survival of Bacteroides intermedius in five transport media, alone or in the presence of Streptococcus sanguis.

The survival rate of Bacteroides intermedius was first tested in monoculture, and Streptococcus sanguis was then added in 5 different transport media; 2 nonnutritious media, the viability-preserving medium of the University of Göteborg No. IV (VMG IV), reduced transport fluid (RTF), and 3 nutritious media, thioglycolate medium (TG), peptone yeast extract medium (PY) and PY medium with 1% glucose (PYG). All manipulations were carried out in an anaerobic chamber. After a given transport time (6 or 24 h) aliquots were spread on plates containing solid PY medium by means of an automated spiral system device, thus permitting counts after incubation. The slight variations in the counts of B. intermedius in monoculture, not exceeding 0.5 log10 in the 5 media tested, indicated its good survival capability, i.e. at least 24 h. By contrast, when S. sanguis was added, it was only possible to use nutritious media such as PY or TG for 6 h. In the glocose-containing media (PYG, TG), the multiplication of rapidly glucose-fermenting microorganisms such as streptococci influenced the B. intermedius survival rate. Therefore, the transport time for oral microbiological samples needs to be reduced as much as possible. The use of excessively rich media (particularly media containing a high level of glucose) should be avoided.

Antibiosis↗
PubMed1992

The breakdown and utilization of peptides by strains of Fusobacterium nucleatum.

It has been claimed that most strains of Fusobacterium nucleatum require peptides rather than free amino acids for growth. In contrast, we have shown that, under continuous culture conditions, all strains tested grow in a chemically defined medium (CDM). The purposes of this study were to determine whether resting cells of F. nucleatum could attack unsubstituted peptides and whether growing cells could utilize a peptide fraction prepared from a commercial peptone. Resting cells cleaved all 19 peptides, containing 3-6 residues, and the 4 key energy-yielding amino acids--Glu, His, Ser and Lys--were rapidly taken up. A hydrophilic Casitone fraction, rich in Glu, promoted growth and peptides < 1 kDa were rapidly utilized. The cleaved residues metabolized were those previously shown to limit growth in CDM: Glu, Ser, His and Lys. The endopeptidase activities of Porphyromonas gingivalis would provide the necessary peptides for the growth of F. nucleatum, which may partly explain why these two organisms frequently coexist in periodontally diseased sites.

Amino Acids↗
PubMed2006

Molecular characterization of thermostable direct haemolysin-related haemolysin (TRH)-positive Vibrio parahaemolyticus from oysters in Mangalore, India.

Pathogenic Vibrio parahaemolyticus strains producing either or both of a thermostable direct haemolysin (TDH) and a TDH-related haemolysin (TRH) encoded by tdh and trh genes, respectively, are isolated at a low rate from the environment. However, recently we observed that a considerable percentage of APW (alkaline peptone water) enrichment broths of oysters collected off Mangalore India, were trh(+), rather than tdh(+) by PCR. In order to further investigate the prevalence and genetic diversity of trh bearing V. parahaemolyticus in our coast, we attempted to isolate and characterize trh(+)V. parahaemolyticus from oysters. A total of 27 trh(+) strains were isolated during the period between March 2002 and February 2004, of which nine were also tdh(+). All the trh(+) isolates were positive for urease phenotype. The isolates belonged to diverse phenotypes. In order to explore the possible presence of heterogeneity in the trh gene region among trh(+)V. parahaemolyticus, a 1.5 kb region around trh gene was PCR amplified and restriction digested using selected restriction enzymes. The whole genome comparison of strains was performed by randomly amplified polymorphic DNA PCR (RAPD PCR). The PCR-RFLP results revealed fairly well conserved nature of the trh gene region studied in different serotypes. Though 11 strains were positive by PCR for a genomic fragment that has been reported to be amplified in pandemic strains, all strains were negative by group-specific PCR (GS-PCR), orf8 PCR and showed a different RAPD pattern compared with pandemic strains. The results suggest that genetically diverse V. parahaemolyticus carrying virulence genes are associated with the aquatic environment in this region.

Alkalies↗