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PubMed1993

Endogenous cholecystokinin in the control of gastric emptying of liquid nutrient loads in rhesus monkeys.

A role for the brain/gut peptide cholecystokinin (CCK) in the control of gastric emptying has been proposed. In the present studies, we have used a potent type A CCK-receptor antagonist (devazepide) to examine the quantitative contribution of endogenously released CCK in the control of liquid gastric emptying of 100 ml lipid, protein, and carbohydrate test loads in rhesus monkeys. Emptying was studied in conscious monkeys equipped with chronic indwelling gastric cannulas. Prior intragastric administration of devazepide (1.0-320 micrograms/kg) differentially affected the 10-min emptying of glucose (0.125/ml), peptone (4.5%), and Intralipid (4.5%). Glucose emptying was not affected by any dose of the CCK antagonist. The emptying of peptone was accelerated by doses of 10 micrograms/kg or higher. This effect, however, was only partial and plateaued at a dose of 100 micrograms/kg. The gastric emptying of Intralipid was accelerated at a dose of 32 micrograms/kg, and the inhibitory effect of the Intralipid was completely eliminated at a dose of 320 micrograms/kg. At this dose of devazepide, the Intralipid test meal emptied from the stomach at the same rate as physiological saline. These data demonstrate that in rhesus monkeys endogenously released CCK 1) does not play a role in the control of glucose emptying, 2) is a partial mediator of the inhibitory action of peptone on gastric emptying, and 3) is the primary inhibitory mediator in the control of the gastric emptying of Intralipid.

Animals↗

PubMed1987

Regulation of gastric acid secretion by neurotensin in man. Evidence against a hormonal role.

The present study was designed to evaluate neurotensin as a hormonal regulator of gastric acid secretion in man. After a fat-rich meal, the strongest known stimulus of neurotensin release, plasma neurotensin-like immunoreactivity (NTLI) was elevated from 7.6 +/- 1.9 to 15.5 +/- 2.5 pM. Plasma NTLI was measured with antiserum L170, which requires the biologically active carboxyl-terminal hexapeptide of the neurotensin molecule for recognition and does not crossreact significantly with any known natural catabolite in human plasma. Intravenous infusion of neurotensin at 25 pmol X kg-1 h-1 resulted in a plasma level of 14.7 +/- 2.1 pM, similar to the maximal physiological level observed after the fat-rich meal. Intravenous infusion of neurotensin at 25 pmol X kg-1 h-1 during 2 h, however, failed to significantly inhibit peptone meal-stimulated gastric acid secretion measured by intragastric titration. The 2-h acid output to peptone was 40.8 +/- 6.2 and 41.3 +/- 6.9 mmol during the vehicle and the neurotensin infusion, respectively. Intravenous infusion of neurotensin at 100 or 400 pmol X kg-1 h-1 did not affect acid output, whereas at 1,600 pmol X kg-1 h-1, which resulted in a plasma neurotensin concentration of 725 +/- 80 pM, significantly reduced peptone meal-stimulated gastric acid secretion. The neurotensin-induced inhibition of acid output was independent of the hormone gastrin. The present results provide evidence against a hormonal role for neurotensin in the regulation of meal-stimulated gastric acid secretion in man.

Adolescent↗

PubMed2006

Production of electricity from proteins using a microbial fuel cell.

Electricity generation was examined from proteins and a protein-rich wastewater using a single chamber microbial fuel cell (MFC). The maximum power densities achieved were 354 +/- 10 mW/m2 using bovine serum albumin (BSA) and 269 +/- 14 mW/m2 using peptone (1100 mg/L BSA and 300 mg/L peptone). The recovery of organic matter as electricity, defined as the Coulombic efficiency (CE), was comparable to that obtained with other substrates with CE = 20.6% for BSA and CE = 6.0% for peptone. A meat packing wastewater (MPW), diluted to 1420 mg/L chemical oxygen demand, produced 80 +/- 1 mW/m2, and power was increased by 33% by adding salt (300 mg/L sodium chloride) to increase solution conductivity. A wastewater inoculum generated 33% less power than the MPW inoculum. The MFC was an effective method of wastewater treatment, demonstrated by >86% of biochemical oxygen demand and total organic carbon removal from wastewater.

Bioelectric Energy Sources↗

PubMed1980

Somatostatin and gastrin release from canine stomach.

Somatostatin and gastrin release into the veins draining the stomach was studied in 27 anaesthetized dogs. Basal somatostatin-like immunoreactivity (SLI) in corpus veins (136 +/- 36 pg/ml) was significantly higher than in antrum veins (83 +/- 20 pg/ml; p less than 0.05) and the femoral artery (58 +/- 15 pg/ml; p less than 0.02). During peptone, pH 6.5, perfusion of the stomach, SLI concentration increased significantly in the corpus veins to approximately four times basal and in the antrum veins to three times basal, whereas SLI levels in the peripheral circulation remained constant. Peptone, pH 3.5, and sodium oleate did not stimulate gastric SLI. Gastric distension increased significantly SLI release from the corpus. In gel filtration studies 50%--70% of SLI from gastric vein plasma samples but greater than 90% from femoral artery samples eluted in the void volume of Sephadex G-25 columns. Gastrin secretion was stimulated significantly only by peptone, pH 6.5.

Animals↗

PubMed1991

[The enzyme release by Trichophyton rubrum is dependent on nutritional substance supply].

Enzymes liberated by growing dermatophytes are of pathogenetic importance in tinea. To investigate the influence of nutrients on this enzyme release, Trichophyton rubrum was grown in media containing peptone, keratin and lipids, to which glucose was added in separate assays. The culture supernatants were compared for extracellular enzyme activities by use of the api-zym-test. Our results clearly show that the extracellular enzyme activity is dependent on the nutrients supplied. Seven different enzymes were released when keratin was supplied, as compared to only 5 and 2, respectively, when lipids or peptone were available. Among these enzymes alkaline phosphatase and N-acetyl-beta-glucosaminidase were detected in all cultures lacking glucose. Enzyme release was inhibited completely when glucose was added to the media, except for N-acetyl-beta-glucosaminidase in peptone cultures. This dependency of enzyme release on fungal nutrition can be expected to occur in vivo, too. In addition, it has to be considered for in vitro cultural conditions. Alkaline phosphatase and acetyl-glucosaminidase may be more important in tinea than has been assumed so far.

Culture Media↗

PubMed1979

Some aspects of FMDV-production in growing cells and a closed system for concentration of FMDV by polyethylene glycol.

Different commercially available peptone preparations, all derived by enzymatic digestion of meat, were tested for their ability to replace the individual amino acids and polyethylene glycol (PEG)-treated serum in BHK suspended cell culture growth medium. Cell growth was not impaired if the individual amino acids were replaced by 3 g/l of peptone in combination with 3 g/l LAH and 5% PEG-treated bovine serum. The concentration of the latter could be reduced to 1% by gradually lowering the concentration in successive cell passages. No significant differences in growth stimulating properties were observed between the peptone preparations. The virus produced was concentrated and partly purified by precipitation with PEG, collection of the precipitate by filter-aid filtration and direct elution from filter cake in the filter by pumping one tenth the original volume of buffer through the filter. The whole procedure was performed in a simple closed system, offering maximum guarantee of bacteriological sterility and preventing virus aerosol formation in the surroundings.

Animals↗

PubMed1987

Effect of poly I:C-activated peritoneal cells on the take of transplantable murine tumours.

The effect of syngeneic mouse peritoneal cells (PC) on the growth of four different transplantable tumours was studied in adoptive transfer experiments (Winn's test). PC from unstimulated mice did not influence the growth of a benzpyrene induced fibrosarcoma (BaF1) and a methylcholantrene induced mastocytoma (P815), but significantly enhanced the growth of a spontaneous adenocarcinoma (Sp4) and Lewis lung carcinoma (LL). PC induced by a single injection of thioglycollate did not influence, whereas PC elicited by proteose peptone markedly enhanced the growth of BaF1 fibrosarcoma. The enhancing effect of peptone induced PC was diminished by a single intraperitoneal dose (100 micrograms/mouse) of polyinosinic-polycytidylic acid (poly I:C) given after peptone injection. Transferring PC obtained after a single injection of poly I:C (100 micrograms intraperitoneally) resulted in retardation of growth of BaF1 fibrosarcoma and Sp4 adenocarcinoma or in a marked decrease in their take depending on the PC/tumour cell ratio. The effector cells involved in the protective effect proved to be different, using these two tumour models. Lewis lung carcinoma and P815 mastocytoma proved to be insensitive to poly I:C-stimulated PC.

Adenocarcinoma↗

PubMed1983

Dose-response study of omeprazole on meal-stimulated gastric acid secretion and gastrin release.

In a placebo-controlled, double-blind, crossover, and randomized trial, the effect of 30, 60, and 90 mg of oral omeprazole on peptone-stimulated gastric acid secretion and synchronously measured gastrin release was studied in 8 healthy subjects. Peptone-stimulated acid output was reduced dose-dependently by 42%, 80%, and 92%, respectively. In spite of a short mean plasma half-life of 52 min, the inhibitory effect lasted for greater than 4.5 h and was significantly correlated to the area under the plasma concentration time curve for omeprazole. Mean basal serum gastrin and gastrin profiles increased insignificantly without alteration of integrated gastrin output and did not show any correlation either to the omeprazole area under the plasma concentration time curve or to the inhibition of peptone-stimulated acid secretion. Side effects, significant alterations of laboratory screen, or alterations of serum concentrations of thyroid hormones were not detected. In conclusion, omeprazole is a potent and, under the conditions tested, well-tolerated inhibitor of meal-stimulated gastric acid secretion in humans.

Adult↗

PubMed1981

Mixed culture studies of Streptococcus mitis and oral enterococci.

Strains of Streptococcus mitis and oral enterococci were grown in mixed culture in 0.5% peptone, 1.0% peptone and 1.0% peptone supplemented with 0.5% glucose. In all three media the enterococci inhibited the S. mitis strains. The inhibition was strongest in the glucose supplemented broths, probably due to pH toxicity. Inhibition in the unsupplemented broths was not similarly caused, but no other inhibitory factors could be isolated from these culture.

Culture Media↗

PubMed1976

[Study of the fractional makeup of diagnostic nutrient media for isolating Vibrio cholerae].

A study was made of the fractional composition of peptones used for preparation of solid nutrient media. It was shown that the best growth of the vibrio on these media was obtained with the use of highly split peptones. Examination of fractional composition of peptone by gel-filtration and fractionation with various precipitants is recommended for rational working out of nutrient media for cultivation of cholera vibrio.

Chromatography, Gel↗

PubMed2001

Production of tissue plasminogen activator (t-PA) in Aspergillus niger.

A protease-deficient strain of Aspergillus niger has been used as a host for the production of human tissue plasminogen activator (t-PA). In defined medium, up to 0.07 mg t-PA (g biomass)(-1) was produced in batch and fed-batch cultures and production was increased two- to threefold in two-phase batch cultures in which additional glucose was provided as a single pulse at the end of the first batch growth phase. Production was increased [up to 1.9 mg t-PA (g biomass)(-1)] by the addition of soy peptone to the defined medium. The rate of t-PA production in batch cultures supplemented with soy peptone (0.2 to 0.6 mg t-PA L(-1) h(-1)) was comparable to rates observed previously in high-producing mammalian or insect cell cultures. In glucose-limited chemostat culture supplemented with soy peptone, t-PA was produced at a rate of 0.7 mg t-PA L(-1) h(-1). Expression of t-PA in A. niger resulted in increased expression of genes (bipA, pdiA, and cypB) involved in the unfolded protein response (UPR). However, when cypB was overexpressed in a t-PA-producing strain, t-PA production was not increased. The t-PA produced in A. niger was cleaved into two chains of similar molecular weight to two-chain human melanoma t-PA. The two chains appeared to be stable for at least 16 h in culture supernatant of the host strain. However, in general, <1% of the t-PA produced in A. niger was active, and active t-PA disappeared from the culture supernatant during the stationary phase of batch cultures, suggesting that the two-chain t-PA may have been incorrectly processed or that initial proteolytic cleavage occurred within the proteolytic domain of the protein. Total t-PA (detected by enzyme-linked immunoassay) also eventually disappeared from culture supernatants, confirming significant extracellular proteolytic activity, even though the host strain was protease-deficient.

Aspergillus niger↗

PubMed2005

Medium optimization for hen egg white lysozyme production by recombinant Aspergillus niger using statistical methods.

Statistics-based experimental design was used to investigate the effect of medium components (starch, peptone, ammonium sulfate, yeast extract, and CaCl2.2H2O) on hen's egg white lysozyme production by Aspergillus niger HEWL WT-13-16. A 2(5-1) fractional factorial design augmented with center points revealed that peptone, starch, and ammonium sulfate were the most significant factors, whereas the other factors were not important within the levels tested. The method of steepest ascent was used to approach the proximity of optimum. This task was followed by a central composite design to develop a response surface for medium optimization. The optimum medium composition for lysozyme production was found to be: starch 34 g L-1, peptone 34 g L-1, ammonium sulfate 11.9 g L-1, yeast extract 0.5 g L-1, and CaCl2.2H2O 0.5 g L-1. This medium was projected to produce, theoretically, 212 mg L-1 lysozyme. Using this medium, an experimental maximum lysozyme concentration of 209+/-18 mg L-1 verified the applied methodology.

Algorithms↗

PubMed1987

Differential protein synthesis by murine peritoneal macrophages elicited by various stimuli.

Protein synthetic patterns of murine peritoneal macrophages were analyzed by two-dimensional polyacrylamide gel electrophoresis (2D PAGE) of 35S methionine-labeled proteins. While the protein synthetic patterns exhibited by resident, inflammatory, and activated macrophages had numerous common features that distinguished them from the other normal non-macrophage cell types examined, unique proteins also characterized each macrophage population from the others. The accumulation by resident macrophages of proteins 23, 25, and 37 distinguished them from elicited cells, as did the former's more abundant synthesis of proteins 54 and 52. The protein synthetic patterns of inflammatory thioglycollate- and proteose peptone-elicited macrophages were strikingly similar, save for the former's greater levels of accumulation of proteins 14 and 28, and the latter's more pronounced expression of p23.5. Peritoneal macrophages elicited by treatment with heat-killed Propionibacterium acnes, the live, attenuated Mycobacterium bovis strain BCG, Listeria monocytogenes, and the protozoan flagellate Trypanosoma rhodesiense, all exhibited tumoricidal activity in 16-h or 72-h functional assays. They shared a common protein synthetic profile that differentiated them from the synthetic patterns characteristic of the non-tumoricidal resident and inflammatory macrophages. These tumoricidal macrophages were unique in synthesizing a protein(s) of approximate molecular weight 26,000 daltons. A time-course study employing P. acnes-activated peritoneal macrophages indicated that p26 accumulation decayed with tumoricidal capacity as a function of time in culture, although no direct correlation between lytic activity and p26 expression could be definitively established. Peritoneal macrophages elicited with proteose peptone were not directly tumoricidal but were rendered so upon in vitro treatment with nanogram amounts of bacterial lipopolysaccharide. The accumulation of low levels of p26 by the newly explanted proteose peptone-elicited macrophages suggests the possibility that this protein characterizes macrophage populations primed as well as triggered for tumoricidal activity.

Animals↗

PubMed1977

Anaerobic growth of Escherichia coli on formate by reduction of nitrate, fumarate, and trimethylamine N-oxide.

Anaerobic growth of E. coli, strain K-10, depending on formate oxidation by nitrate, fumarate, and trimethylamine N-oxide was followed in a medium containing peptone. The presence of formate and peptone was indispensable for growth with fumarate and trimethylamine N-oxide reduction. While there was no growth in the absence of acceptor, growth was observed in the absence of formate by nitrate reduction though not as much as under aerobic conditions. Per mole consumed formate equimolar succinate or trimethylamine was formed, but 1.2 mole of nitrate was produced, probably depending partly on peptone oxidation. The molar growth yield on formate was found to be 6.5, 7.6, and 7.0 g cells/mole depending on the reduction of nitrate, fumarate, and trimethylamine N-oxide, respectively, suggesting the formation of one mole ATP coupled to the anaerobic electron transfers from formate.

Aerobiosis↗

PubMed1980

Carbohydrate dissimilation tests in the identification of staphylococci.

Reproducible and comparable results were obtained in different media containing different nutrients and indicators when representative Staphylococcus strains were tested for acid production from carbohydrates. Only in tests with melezitose, ribose and turanose many discrepant, weak or delayed positive reactions occurred. In tests with other carbohydrates similarly many weak results were visible after 1 day of incubation, but acid reactions were clear and easy to read after 2 days in phenol red broth and Andrade peptone water media, commonly used in the routine identification of other bacterial genera. Important alkalinization effects were observed after prolonged incubation, but not after short periods up to 24 h in peptone-rich test media. Growth was poor and numbers of acid reactions from carbohydrate breakdown detected did not increase when peptone-free media were used.

Bacteriological Techniques↗

PubMed1991

Intracolonic fat inhibits gastric acid secretion independent of gastrin release in the dog.

The purpose of this study was to examine the effect of perfusion of the colon with a fatty acid (oleic acid) on peptone-stimulated gastric acid secretion and release of gastrin in conscious dogs. Gastric acid secretion was monitored by continuous intragastric titration. Perfusion of the colon with sodium oleate (24 mmol/hr) inhibited gastric acid secretion (14.2 +/- 2.6 meq/hr) stimulated by a peptone meal (1%) significantly (P less than 0.05) when compared to perfusion of the colon with saline alone (20.1 +/- 1.6 meq/hr). The serum elevation in gastrin in response to intragastric instillation of the peptone meal was not affected by the colonic perfusion of oleic acid. Plasma concentrations of peptide YY (PYY) increased significantly in response to perfusion of the colon with saline or sodium oleate, and the integrated release of PYY in response to sodium oleate [6.9 +/- 2.8 ng (60-120) min/ml] was significantly greater than the response to saline [3.1 +/- 0.7 ng (60-120) min/ml]. The results of this study indicate that inhibition of gastric acid secretion by perfusion of the colon with fat is not due to an inhibition of gastrin release. In addition, because PYY is an inhibitor of gastric acid secretion, it is possible that PYY participates as an inhibitor of gastric acid secretion by the colon.

Animals↗

PubMed1994

The involvement of muscarinic receptors in gastric liquid emptying in the conscious rat following Roux-en-Y-antrectomy.

The gastric emptying of liquid test meals is dependent on resistance to flow at the pylorus and on pressure gradients between the duodenum and the body of the stomach. In the present study, we investigated the role and subtypes of muscarinic receptors during gastric emptying of various liquid test meals in conscious rats with gastric fistula after Roux-en-Y antrectomy. In the control rats with gastric fistula but with intact reflex pathways and pylorus, the non-selective muscarinic antagonist atropine (7 mg/kg i.p.) and M1-selective pirenzepine (7 mg/kg i.p.), acting possibly on M1 receptors, delayed saline emptying by suppressing cholinergic tone and thus relaxing the body of the stomach and contracting the pyloric sphincter. On the other hand, in Roux-rats saline and hyperosmolal saline emptying were not significantly affected, while the inhibitory effect of HCl was completely reversed. Furthermore, peptone-induced delay of gastric emptying in control rats was also reduced in Roux-rats. Pirenzepine abolished the facilitating effects of Roux-en-Y operation on acid and peptone emptying and M2-selective antagonist AF DX-116 (7 mg/kg i.p.) did not have any inhibitory effect in this regard. In conclusion, Roux-en-Y gastrectomy without vagotomy does not slow gastric emptying of liquids, and it reverses the inhibitory effects of peptone and acid through an atropine- and pirenzepine-sensitive pathway.

Anastomosis, Roux-en-Y↗

PubMed1995

Doublet cells in Tetrahymena as indicators of culture media composition.

Stomatogenesis in ciliates is a complex and carefully orchestrated event. The exo- mutant SB255 of Tetrahymena thermophila has defects in mucocyst formation and docking and can also have one or two mouths. Three common culture media (proteose peptone, Medium 357, and yeast extract) were analyzed for total C, N, and inorganic elements and then tested for their effect on the number of mouths present in SB255. Cultures of SB255 grown in Medium 357 consisted of a mixed population of cells with either two mouths (doublet) or one mouth. Cultures from the same original stock grown in Medium 357 (SBm) and in 1% proteose peptone (SBpp) had different percentages of doublet cells in 1-, 2-, 3-, and 4-d-old cultures. When transferred to and grown in 1% yeast medium, both SBpp and SBm cultures had increased percentages of doublets over a 4-d culture period. When grown in 0.1, 0.5, or 1% yeast medium for 2 d, both SBpp and SBm cultures had more doublets in 1% than in either 0.1 or 0.5% yeast medium. Cultures of SBm grown in Medium 357 or 1% yeast medium for 2 d had a 10-fold increase in doublet cells compared to the inoculum. After 2 d in 1% proteose peptone, SBm cultures had percentages of doublet cells almost equal to that of the inoculum. Immunofluorescence and scanning electron microscopy (SEM) were used to examine cellular morphology of the doublet cells. These findings suggest that enriched media promote the growth of doublet cells. Furthermore, these doublets could prove to be a useful model system for the study of biological roles of trace elements.

Animals↗