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PubMedDate not supplied

[Effect of hyperthyroidization on (pro)insulin biosynthesis and secretion].

Insulin production and secretion in simulated rat hyperthyrosis induced by L-thyroxin, injected intraperitoneally during 8 to 30 days, were studied on isolated Langerhans' islets, using collagenase fermentation. Insulin secretion in vitro was determined by radioimmunoassay, its biosynthesis being evaluated according to 3H-leucine incorporation into de novo formed islet proteins with insulin immunoreactivity. The dissociated effect of thyroxin on the secretory response of beta-cells and their hormone production was revealed. In hyperthyroidized animals a decrease in the islet insulin secretion was seen in the presence of a low glucose content in the incubating medium (5 mM), (pro-)insulin biosynthesis remaining unchanged. (Pro-)insulin concentration increased comparatively to the control following 8-day thyroxin injection under condition of the islet incubation with 15 mM of glucose. Insulin secretion returns to normal after augmentation of hexose content in the incubating medium up to 15 mM (hormone production being not inhibited), indicating the functional character of a decrease in beta-cell secretory response and a significant role in its genesis of the changed beta-cell sensitivity to glucose action, inducing insulin secretion.

Animals↗
PubMed1994

[The effect of cadmium on the protozoan population and rumen fermentation of feed in an artificial rumen].

In our experiment, the effects of 5, 10 and 20 mg cadmium per kg dry matter (DM) on protozoan population and rumen fermentation of feed ration consisting of 11.7 g DM of hay and 2.8 g DM of barley (80: 20%) were followed in artificial rumen (Rusitec). The results of the experiment showed that the addition of 5 and 10 mg cadmium per kg DM less significantly (P < 0.05) decreased the digestibility of DM, organic matter and neutral detergent fibre and significantly (P < 0.01) decreased the digestibility of cellulose of feed ration. It is interesting that the addition of 20 mg cadmium per kg DM did not influence these parameters. Although the total gas production showed a tendency of decrease due to the influence of the addition of 5, 10 and 20 mg cadmium/kg DM, methane and CO2 production was not altered. However, cadmium significantly influenced the production of individual volatile fatty acids-VFA's (mmol/day). The addition of 5, 10 and 20 mg cadmium per kg DM significantly increased acetic acid production (by 10-20%) and decreased propionic acid production (by 18-30%). Therefore, the acetate: propionate ratio was significantly increased (from 1.57 to 2.45-2.60) by the addition of cadmium. The production of n-valeric and iso-valeric acids was also significantly decreased in comparison with the control. The decrease of individual VFA's was more significant at the higher amount of cadmium added into the fermentation system. The proportions of individual VFA's in total VFA production expressed in molar % showed a similar character. The changes in the production of individual VFA's due to the influence of the addition of 5, 10 and 20 mg cadmium per kg DM caused a decrease in energetic efficiency of VFA's (P < 0.001) in comparison with the control. The other parameters of rumen fermentation - utilization of glucose, adenosine triphosphate (ATP) production, fermented hexose, fermented amino acids and fermented organic matter (OMF) were not influenced by the cadmium addition. Although the total microbial matter production in effluent and undigested feed (residues) was significantly (P < 0.001) decreased by the addition of 5, 10 and 20 mg cadmium per kg DM, the efficiency of microbial synthesis expressed as YATP and g microbial N/kg OMF was not changed and achieved the values 11.78-12.68 (YATP), 25.56-28.35 (g microbial N/kg OMF), respectively. The total protozoan population was significantly decreased by the cadmium addition mainly as a result of the decrease of infusoria of Entodinium spp.(ABSTRACT TRUNCATED AT 400 WORDS)

Animal Feed↗
PubMed1996

Evaluation of the stimulatory activity of a fermented mistletoe lectin-1 free mistletoe extract on T-helper cells and monocytes in healthy individuals in vitro.

Previously, a strong stimulatory response of peripheral blood mononuclear cells (PBMC) to a fermented mistletoe extract (Iscador Pini, i.p.) could be observed in normal and allergic individuals. Aim of this study was therefore to analyse the cell subtypes involved in this in vitro reactivity. PBMC from 11 non-mistletoe treated healthy and allergic individuals were therefore investigated. Flow cytometric analyses revealed that this mistletoe extract stimulated T-cells (CD3+), especially T-helper cells (CD4+), as well as monocytes at concentrations of 100 or 1,000 micrograms/ml. Furthermore, an increased proportion of T- and T-helper cells expressing the interleukin-2 (IL-2) receptor (CD25) and monocytes expressing HLA-DR molecules, respectively, could be demonstrated. There was no evidence for a major involvement of B- (CD19+), natural killer- (NK-; CD56+) and T-suppressor cells/cytotoxic T-lymphocytes (CD8+). To get more insights whether the T-cell proliferation induced by i.p. was the consequence of a primary or a secondary type of immune response, kinetic studies (n = 5) were performed hereby comparing the reactivity of the non-recall antigen keyhole limpet hemocyanin (KLH) as well as the recall antigen purified protein derivative (PPD) derived from Mycobacterium tuberculosis with that of i.p. I.p. at a concentration of 100 micrograms/ml always exhibited the kinetics of a primary immune reaction. These findings were further substantiated by additional flow cytometric studies analysing changes in the proportions of naive (CD45RA+) and memory/effector cells (CD45RO+) during the exposure to i.p. It could be shown that the proportion of naive cells decreased and that of the transition stage increased, which could indicate that there was a change towards memory/effector cells. In conclusion, these data demonstrate that i.p.-related antigens act like "non-recall"-antigens, and the in vitro immune response involves T-cells as well as monocytes.

Adjuvants, Immunologic↗
PubMed1996

Peroxidase-catalyzed generation of catechin oligomers that inhibit glucosyltransferase from Streptococcus sobrinus.

Oolong tea extract (OTE) and the purified polymeric polyphenols from OTE have been found to inhibit glucosyltransferase (GTase) of mutans streptococci. In view of the partial fermentation characteristic of oolong tea, we describe here an in vitro model reaction system to produce partially fermented products of D-(+)-catechin or green tea extract (GTE) using horseradish peroxidase. A dimeric catechin molecule was identified as dehydro-dicatechin A by instrumental analyses. The molecular size of some oligomeric catechins was estimated by the elution profile with HPLC. These catechin oligomers markedly inhibited GTase from Streptococcus sobrinus 6715. As the degree of polymerization of catechin or GTE increased, GTase was inhibited more effectively. These results suggest that polymeric polyphenols found in OTE are synthesized by partial fermentation due to oxidases/peroxidases present in tea leaves.

Bacterial Adhesion↗
PubMed2001

Influence of nitrogen source on the fermentation of fibre from barley straw and sugarbeet pulp by ruminal micro-organisms in vitro.

Incubations were carried out with a batch culture system to study the effects of different N sources on the fermentation by ruminal micro-organisms from Merino sheep of two fibre substrates derived from feedstuffs that differed in their fermentation rate. The substrates were neutral-detergent fibre (NDF) from barley straw and sugarbeet pulp. N sources were ammonia (NH4Cl) and peptides (Trypticase). Three treatments were made by replacing ammonia-N with peptide-N at levels of 0 (AMMO), 33 (PEPLOW) and 66 % (PEPHIGH) of total N. There were no differences (P>0.05) between treatments in NDF degradation for both the barley straw and the sugarbeet pulp. Peptides increased (P<0.05) total volatile fatty acids daily production for both substrates, with greater values (P<0.001) for PEPHIGH than for PEPLOW for the sugarbeet pulp. The presence of peptides also increased (P<0.05) microbial N synthesis compared with AMMO, with PEPHIGH supporting more growth (P<0.001) than PEPLOW when the sugarbeet pulp NDF was fermented. The presence of peptides increased (P<0.01) the amount of solids-associated micro-organisms (SAM)-N for both the barley straw and the sugarbeet pulp fibres, values in the PEPHIGH treatment being higher (P<0.001) than those in PEPLOW. The proportion of SAM-N in the total microbial N was not affected (P>0.05) by the presence of peptides compared with the AMMO treatment, but values were greater for the PEPHIGH compared with the PEPLOW N source, reaching statistical significance (P<0.05) only for the sugarbeet pulp. For liquid-associated micro-organisms, the AMMO treatment resulted in the greatest (P<0.05) proportion of N derived from ammonia for both substrates, with a further decrease (P<0.01) for the PEPHIGH treatment compared with the PEPLOW for the sugarbeet pulp, indicating preferential uptake of peptides when they were available. Microbial growth efficiency (g microbial N/kg NDF degraded) was not affected (P>0.05) by N source. These results indicate that N forms other than ammonia are needed for maximal growth of fibre-digesting ruminal micro-organisms.

Animal Feed↗
PubMed1995

Effects of protein source on nitrogen metabolism in continuous culture and intestinal digestion in vitro.

Eight dual flow continuous culture fermenters were used in four replicated periods to study the effects of protein supplements on ruminal fermentation and CP digestion. A basal diet was supplemented with isonitrogenous amounts of urea and tryptone (control; CTRL), soybean meal (SBM), lignosulfonate-treated SBM (LSBM), corn gluten meal (CGM), blood meal (BM), hydrolyzed feather meal (HFM), fish meal (FM), or meat and bone meal (MBM). Digestion of DM, OM, and carbohydrates was not affected by treatment. Ammonia N concentration was highest (P < .05) for CTRL and lowest (P < .05) for LSBM, CGM, BM, HFM, and FM. Nonammonia N flow was lowest (P < .05) for CTRL. Dietary N flow was lowest (P < .05) for CTRL, intermediate for SBM, and highest (P < .05) for LSBM, CGM, BM, HFM, FM, and MBM. Total N flow, bacterial N flow, and efficiency of microbial protein synthesis were not affected by treatment. Protein degradation was highest (P < .05) for CTRL. Flow of total amino acids (AA) was lowest (P < .05) for CTRL, SBM, and MBM. Diets containing BM provided the largest (P < .05) amounts of essential AA and lysine, and FM provided the largest (P < .05) amounts of methionine in fermenter effluent. Supplementation of diets with proteins low in ruminal degradability increased flows of nonammonia N, dietary N, and total and essential AA and modified the AA profile flowing out of fermenters.

Amino Acids↗
PubMed2004

Soybean milk residue ensiled with peanut hulls: fermentation acids, cell wall composition, and silage utilization by mixed ruminal microorganisms.

Preservation of soybean milk residue (SMR) by ensiling with peanut hulls (PEH) and subsequent utilization of silage by mixed ruminal microorganisms were investigated. Treatments were combinations of SMR with PEH at the following ratios: 100:0, 78:22, 71:29, and 60:40 (fresh weight basis). After eight weeks of ensiling, silage lactic acid, crude protein, ether extract, and non-fiber carbohydrates were highest when SMR was ensiled alone and reduced as amounts of SMR decreased. Similar trends were observed for silage in vitro dry matter digestibility, and gas and volatile fatty acid production by ruminal microorganisms. Conversely, silage pH, dry matter, neutral detergent fiber, acid detergent fiber, cellulose, and lignin increased accordingly. The ensiling treatment appeared to alter silage cell wall composition. In particular, silage treated with PEH at the low level (78:22) resulted in reduced fiber contents and lignification. The silage (SMR:PEH=78:22) had enhanced efficiency of both silage fermentation and in vitro ruminal fermentation pattern.

Animals↗
PubMed1995

Factors influencing the 1-g 14C-D-xylose breath test for bacterial overgrowth.

OBJECTIVES: To document the sensitivity of the 1-g 14C-D-xylose breath test for bacterial overgrowth and to investigate luminal and nonluminal factors that may influence breath 14CO2 levels and impact on the clinical utility of this test. METHODS: Thirty-five adult subjects were investigated for bacterial overgrowth by culture of gastric and small intestinal aspirates and by a 1-g 14C-D-xylose breath test. Body weight, gastroduodenal pH and the in vitro capability of overgrowth flora to ferment D-xylose were assessed. Serial breath 14CO2 levels were also recorded before and after the resolution of malabsorption in a subject with celiac disease to determine the importance of postabsorptive metabolism of this substrate. RESULTS: Gastric and small intestinal bacterial overgrowth were present in 19/35 (54.3%) and 21/35 (60.0%) subjects, respectively. The positivity rate of culture of aspirate exceeded that of the 1-g 14C-D-xylose breath test. Endogenous CO2 production independently influenced breath 14CO2 levels. After excluding this influence, sensitivity of the 1-g 14C-D-xylose breath test for gastric bacterial overgrowth or small intestinal bacterial overgrowth was poor, even when overgrowth with specific "marker organisms" was considered. Poor sensitivity could not be explained by unfavorable luminal pH. Overgrowth flora were proven capable of in vitro D-xylose fermentation in 81.8% of subjects. Systemic and/or colonic metabolism of 1-g 14C-D-xylose appear to be important factors influencing results of the 1-g 14C-D-xylose breath test, especially in partial gastrectomy subjects. CONCLUSIONS: The 1-g 14C-D-xylose breath test is not a suitable alternative to culture of aspirate for the investigation of subjects for bacterial overgrowth.

Aged↗
PubMed1973

U-42, 126, a new antimetabolite antibiotic: production, biological activity, and taxonomy of the producing microorganism.

A new antimetabolite antibiotic, U-42,126, was discovered by use of a specific in vitro screen. U-42,126 was produced by the fermentation of Streptomyces sviceus. Its antimicrobial activity in vitro was limited to fungi. Certain bacteria were inhibited only when cultivated in completely synthetic media. U-42,126 was active in vivo against L1210 leukemia in mice.

Antibiotics, Antineoplastic↗