Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nitrosamines are carcinogenic compounds synthetized from amines and nitrites or nitrates, if nitrates in the reaction medium may be reduced to nitrites. Nitrosation is determined in the digestive tract of several species of laboratory animals. Two physiochemical factors appear to determine in vitro nitrosamine formation: the type of amine and the medium pH. The property of secondary amines to nitrosate is inversely related to amine basicity (checked in vivo), and it increases with the medium acidity. In vitro studies show that different types of bacteria can, even at neutral pH, catalyze nitroamine formation from their precursors. However, the role of digestive tract microbial flora in nitrosamine synthesis in the gut cannot be affirmed due to lack of in vivo studies.
 ...
PMID:[Formation of nitrosamines in the digestive tract]. 2 20

The distribution of radioactivity was measured in rats various times after single intravenous doses of tritium-labelled 2,3-bis-hydroxymethyl-1-methylpyrrole (BHMP). Over half the dose was excreted in urine during the first day; less than a seventh this amount was found in the faeces. The level in glandular stomach was much higher than in any other organ and there was evidence that this was related to the acidity of this tissue. With this exception, the radioactivity in other tissues was lower than after an equivalent dose of tritiated synthanecine A bis-N-ethylcarbamate, and that in liver tissue was more easily solubilised than after the latter compound. The results indicate it is unlikely that more than a small amount of free BHMP is released into the bloodstreams of rats given synthanecine A bis-N-ethylcarbamate. When [3H]BHMP is given by stomach tube much radioactivity remains within the gut and there is no exceptional binding to glandular stomach tissue. Whereas the tissue binding as well as chemical and toxicological properties of BHMP are similar to those of dehydroretronecine, the binding properties of synthanecine A bis-N-ethylcarbamate are likely to resemble those of monocrotaline and similar pyrrolizidine alkaloids.
 ...
PMID:The distribution of radio-activity in rats given [3H]bishydroxymethyl-1-methylpyrrole and its relationship to that from [3H]synthanecine A bis-N-ethylcarbamate. 97 2

The administration of the currently available H2-blockers (at a dosage that induces only partial inhibition of the intragastric acidity) is effective in nearly all peptic ulcer patients in the short and long- term treatment. The benefits of more profound gastric acid inhibition (as achieved with omeprazole) in the short-term treatment of acid peptic diseases has been demonstrated in clinical studies. However, gastric acid has an important physiological role and the potential consequences of profound inhibition of gastric acid include intragastric bacterial colonization and hypergastrinaemia. Bacterial overgrowth of the stomach renders the gut more susceptible to enteric infection and another possible sequela of intragastric bacteria is the formation of N-nitroso compounds with carcinogenic potency. Hypergastrinaemia has a trofic effect on the gastric mucosa and gastric endocrine cells and, in animal, ECL cell hyperplasia and carcinoid formation has been observed as a result of high serum gastrin levels. So far, these potential risks have precluded the long-term administration of omeprazole.
 ...
PMID:Inhibition of gastric acid secretion: advantages and risks in short and long-term treatment. 198 19

We have purified an acidic octapeptide from the neural ganglion of the protochordate Ciona intestinalis by a three-step procedure including C18 Sep-Pak fractionation, MonoQ ion-exchange chromatography, and C4 reversed-phase high-performance liquid chromatography. The purification was monitored by an immunoassay specific for the alpha-carboxyamidated COOH terminus common to the mammalian brain-gut hormones, cholecystokinin and gastrin. Automated Edman degradation revealed the sequence Asn-Tyr-Tyr-Gly-Trp-Met-Asp-Phe. In accordance with the high acidity of the peptide, amino acid analysis after cleavage with aminopeptidase M showed that both tyrosyl residues are sulfated. Hence, the structure is Asn-Tyr(SO3)-Tyr(SO3)-Gly-Trp-Met-Asp-Phe-NH2, as also confirmed by identity with the synthetic disulfated peptide in different chromatographic systems. The occurrence of two consecutively sulfated tyrosyl residues after a neutral residue challenges present concepts of consensus sites for tyrosyl sulfation. We conclude that the structure of the peptide, named cionin, suits that of a common ancestor for cholecystokinin and gastrin.
 ...
PMID:Cionin: a disulfotyrosyl hybrid of cholecystokinin and gastrin from the neural ganglion of the protochordate Ciona intestinalis. 230 39

Acid-base homeostasis depends on glutamine flow from producer organs to those capable of generating bicarbonate. Glutamine oxidation, the prerequisite metabolic transformation, can be expressed by many sites; however, net base generation requires that glutamine flow be directed to a specific organ, the kidney. Normally, glutamine flows from the periphery to the splanchnic bed, providing a major fuel and supporting ureagenesis. Glutamine flow in chronic metabolic acidosis, on the other hand, is rerouted to the kidneys; asymmetrical distribution of NH+4 and HCO3- into the urine and renal vein subserves restoration of alkaline reserves. Clearly, glutamine flows in accordance with physiological demands, yet little is known of the regulatory mechanisms. As a model, chronic metabolic acidosis alters two aspects of this vital flow, its direction and magnitude. Characteristically the direction of flow is away from the splanchnic bed and into the kidneys associated with a marked fall in arterial glutamine concentration, restoring arterial level returns flow to the splanchnic bed sink. Thus glutamine homeostasis is sacrificed to impart direction to interorgan glutamine flow. Although multiple sites contribute to glutamine homeostasis, of great strategic importance is the potent hepatic glutaminase flux activated by portal venous NH+4 fed forward by gut metabolism; local hydrogen ion concentration modulates the effectiveness of this activator. Acute regulation of flow direction can be exerted by the lungs in determining the prevailing pCO2 and cellular acidity; respiratory compensation in chronic acidosis allows the expression of hepatic glutaminase, thereby suppressing arterial glutamine concentration. The enormous magnitude of glutamine flowing from muscle to the kidneys is supported by adaptive increases in glutamine synthetase and mitochondrial glutaminase, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Interorgan glutamine flow in metabolic acidosis. 332 41

Gastric acid secretion, incidence of gastric mucosal lesion, and gut hormone responses were studied in 24 patients with liver cirrhosis. Gastric acid output in these subjects showed normal acidity and was nearly similar to that in patients with gastric ulcer. The incidence of gastric mucosal lesion was high, especially in patients whose plasma disappearance rate of indocyanine green was low. Plasma levels of both gastrin and gastric inhibitory polypeptide were higher in cirrhotic patients than in control subjects both in the fasting state and after the ingestion of a test meal. Gel chromatography of the postprandial plasma of cirrhotics showed a higher immunoreactivity at the second peak than in controls. This is because cirrhotics have a higher percentage of authentic gastric inhibitory polypeptide, although the elution patterns were similar in both groups. It is suggested that impairment of extraction of some molecular components of both gastrin and gastric inhibitory polypeptide may occur in the cirrhotic liver.
 ...
PMID:Gastric acid secretion and gastrin and gastric inhibitory polypeptide release in cirrhotic patients. 388 51

The effect of Np mass and the acidity of the administered Np solutions as well as the age, sex and nutritional status of the animals injected or gavaged with 239Np or 237Np were determined. The latter factor proved to be dominant for absorption of Np from the gut. Thus in fasting weanling and young adult male rats, the absorption of 239Np was sixfold higher (0.18% and 0.12%, respectively) than in fed ones (0.03% and 0.02%, respectively). Absorption by fasted adult females was 0.05% of the administered 239Np, about half of that of adult males. Raising the Np-mass gavaged to fasted female rats to 1 and 10 mg 237Np/kg resulted in an absorption of 0.23% and 0.26%, respectively. Thus, an increased absorption of Np in adult rats seems to be expected only if a large mass is ingested. No dependence of the absorption of Np on nitric acid concentration was found. The data obtained after oral administration of 238Pu and 239Np to adult rats suggest that the f1 factor recommended by the ICRP for fractional absorption of soluble Np compounds from the gut should be decreased, whereas the f1 factor for soluble Pu compounds should be raised.
 ...
PMID:Gastrointestinal absorption of Np in rats. 406 46

Candida albicans was established in large numbers throughout the gut after one oral challenge in the germ-free and in the conventional mouse. Of the strains tested, only the germ-free ND 1 mouse appeared to be susceptible to infection, and this was confined to the stomach mucosa; lesions contained large numbers of hyphal and mycelial forms with blastospores. These forms were also seen in the gut of resistant germ-free ND 4 mice after challenge. Only budding yeast forms were seen in the gut contents from conventional animals. The concentration of sulfhydryl-containing compounds was decreased in the stomach contents from germ-free mice. The stomach tissue of conventional animals seemed to be more acidic than that of germ-free animals, and association of C. albicans with conventional mice neutralized some of this acidity. E(h) values of contents from the gut of unchallenged mice were usually higher in conventional than in germ-free animals; after challenge, the E(h) in both groups decreased. Some reciprocal effects of intestinal microorganisms and host are discussed in relation to intestinal candidiasis.
 ...
PMID:Growth and invasiveness of Candida albicans in the germ-free and conventional mouse after oral challenge. 597 Apr 61

Non-invasive radiotelemetry techniques were used for the in-vivo assessment of gastric acidity and the effect of antacids in non-pregnant women and women in the third trimester of pregnancy. A particulate (magnesium trisilicate mixture) and a non-particulate (sodium citrate) antacid were studied. There was no significant difference in basal gastric acidity and gut transit time between the pregnant and non-pregnant subjects. The median and range of values for the efficacy (defined as the integrated area under the pH/time curves) of sodium citrate was 138.3 pH.min (29.8-520.7) in the non-pregnant and 103.0 pH.min (54.3-375.6) in the pregnant subjects. The median and range of values for the duration of action of sodium citrate were 38.6 (18.1-147.4) min in the non-pregnant and 30.5 (20.0-119.1) min in the pregnant women. Magnesium trisilicate mixture resulted in a greater intragastric pH change and had a greater efficacy than sodium citrate, but the duration of action of the two antacids was similar.
 ...
PMID:The assessment of gastric acidity and antacid effect in pregnant women by a non-invasive radiotelemetry technique. 609 30

Preliminary experiments established that a 0.5-ml inoculum that is introduced directly into the stomach of mice was cleared rapidly into the small intestine. Bicarbonate buffer, but not skim milk, protected such an inoculum from stomach acid until at least 90% of it had entered the small intestine. Passage and survival of various Escherichia coli strains through the mouse gut were tested by introducing a buffered bacterial inoculum directly into the stomach, together with the following two intestinal tracers: Cr(51)Cl(3) and spores of a thermophilic Bacillus sp. Quantitative recovery of excreted bacteria was accomplished by collecting the feces overnight in a refrigerated cage pan. The data show that wild-type E. coli strains and E. coli K-12 are excreted rapidly (98 to 100% within 18 h) in the feces without overall multiplication or death. E. coli varkappa1776 and DP50supF, i.e., strains certified for recombinant DNA experiments underwent rapid death in vivo, such that their excretion in the feces was reduced to approximately 1.1 and 4.7% of the inoculum, respectively. The acidity of the stomach had little bactericidal effect on the E. coli K-12 strain tested, but significantly reduced the survival of more acidsensitive bacteria (Vibrio cholerae) under these conditions. Long-term implantation of E. coli strains into continuous-flow cultures of mouse cecal flora or into conventional mice was difficult to accomplish. In contrast, when the E. coli strain was first inoculated into sterile continuous-flow cultures or into germfree mice, which were subsequently associated with conventional mouse cecal flora, the E. coli strains persisted in a large proportion of the animals at levels resembling E. coli populations in conventional mice. Metabolic adaptation contributed only partially to the success of an E. coli inoculum that was introduced first. A mathematical model is described which explains this phenomenon on the basis of competition for adhesion sites in which an advantage accrues to the bacterium which occupies those sites first. The mathematical model predicts that two or more bacterial strains that compete in the gut for the same limiting nutrient can coexist, if the metabolically less efficient strains have specific adhesion sites available. The specific rate constant of E. coli growth in monoassociated gnotobiotic mice was 2.0 h(-1), whereas the excretion rate in conventional animals was -0.23 h(-1). Consequently, limitation of growth must be regarded as the primary mechanism controlling bacterial populations in the large intestine. The beginnings of a general hypothesis of the ecology of the large intestine are proposed, in which the effects of the competitive metabolic interactions described earlier are modified by the effects of bacterial association with the intestinal wall.
 ...
PMID:Survival and implantation of Escherichia coli in the intestinal tract. 633 89


1 2 3 4 5 6 7 8 Next >>