Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P00790 (PGA)
 2,475 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. In conscious rats provided with Pavlov pouches, with the antrum retained or resected,the gastric secretory response to various stimuli has been studied. Each acid secretory response was related to that obtained with maximal doses of methacholine and histamine in combination, presumed to reflect the maximal secretory capacity of the mucosa. 2. Three weeks after the operation, the maximal acid secretory capacity was 60 percent lower in the antrectomized than in the intact Pavlov pouch rats; the difference was still larger at 6 weeks and 3-5 months, owing to a gradual increase in the rats with the antrum retained. 3. Antrectomy reduced interdigestive secretion of acid to the same degree as the concomitant reduction in maximal secretory capacity. 4. Acid secretion in response to a maximal infusion of pentagastrin was reduced by about 50 percent at 3 and about 65 percent at 6 weeks after antrectomy. No significant difference was, however, noted between the antrectomized and intact rats when the responses were related to the maximal secretory capacity. The dose response curve to pentagastrin revealed a redcued responsiveness to submaximal doses of this agent following antrectomy. 5. The maximal acid secretory response to histamine was reduced after antrectomy, although the sensitivity to submaximal infusions of histamine appeared to be increased. 6. The mean secretroy output to 2-deoxy-D-glucose was reduced by about 65 percent and that to food by about 85 percent following antrectomy. 7. After antrectomy a background infusion of pentagastrin enhanced the secretory responses to 2-deoxy-D-glucose and to food but did not restore the responses to the levels in the intact rats. The feeding responses as related to the maximal secretory capacity were, however, similar in the two groups on infusing pentagastrin in the antrectomized rats. 8. Interdigestive secretion of pepsin was reduced by about 60 percent after antrectomy, while the peak response to 2-deoxy-Dglucose was about twice the interdigestive level in both groups. Pepsin secretion in response to food showed an increased secretion above the interdigestive level of longer duration in the antrectomized than in the intact Pavlov pouch rats. 9. The irreversibily reduced responsiveness of the gastric mucosa after antrectomy is discussed in relation to known morphological and biochemical changes.
 ...
PMID:Alterations in secretory patterns following antrectomy in rats with Pavlov pouches. 109 18

Since flow-through fluorometry seemed to be a workable method for prescreening cytological material, it became important to have available a reliable method of preparing suspensions of single cells with naked nuclei. An experiment was performed with cervical smears and tissue cultures exposed to varying degrees of pepsination and ultrasonication. The results were disappointing as it appeared impossible to digest cytoplasm completely without damaging the nucleus. Ultrasonic treatment appeared to have an effect only in combination with pepsin; sonication therefore is not a useful technique for dispersion of cell clusters. Moreover, a proposal found in the literature to apply sonication to effect selective damage to leukocyte nuclei was assessed but found to be unsuccessful. Pepsin treatment and ultrasonic treatment appeared conclusively to be unreliable methods for preparing suspensions of single and naked nuclei.
 ...
PMID:Preparing cell suspensions from cervical smears with pepsine and ultrasonic treatment. 109 18

Pepsin secretion is stimulated by the back-diffusion of acid across the mucosa of the vagally denervated canine pouch. If back-diffusion is enhanced by damage, pepsin secretion increases. The current study investigates whether this mechanism exists in man. The stomach of normal human volunteers were irrigated for 1 hour with either buffer of 0.01 N HCl, 1 hour with 0.2 N HCl, and a final hour with buffer or 0.01 N HCl. During the middle hour both the concentration and output of pepsin increased three- or fourfold. From these studies it appears that the human gastric mucosa contains a mechanism similar to the dog's which results in the stimulation of pepsin secretion when exposed to acid. This mechanism could be of etiologic significance in gastric ulcer disease, which has been shown to be associated with increased gastric-mucosal permeability.
 ...
PMID:Stimulation of human pepsin output by tropical hydrochloric acid. 109 97

When maintained in organ culture, rabbit gastric mucosal biopsies incorporated [14tc]leucine into tissue protein and secreted labeled protein into culture medium steadily for 24 hr. Incorporation of radioactivity was abolished by cycloheximide. When examined by sodium dodecyl sulfate gel electrophoresis, dextran gel filtration, and ion exchange chromatography, 65 to 90% of macromolecular radioactivity secreted into culture medium migrated coincidentally with enzymatically assayed pepsinogen. Pepsin activity in cultured biopsies did not decrease during 24 hr of organ culture. Nevertheless, pepsin activity increased linearly in culture medium during this period. Acetylcholine markedly stimulated secretion of labeled protein and pepsinogen by cultured biopsies. In the presence of a subthreshold concentration (10(-10) M) of acetylcholine, pentagastrin, secretin, and the octapeptide of cholecystokinin, all stimulated protein secretion. Over-all incorporation of [14C]leucine into protein by cultured biopsies was stimulated by 10(-9) M pentagastrin. These results directly demonstrate: (1) synthesis and secretion of protein and pepsinogen by isolated gastric mucosa, (2) stimulation of gastric secretion of protein by acetylcholine and polypeptide hormones, and (3) stimulation of gastric synthesis of protein by pentagastrin.
 ...
PMID:Synthesis and secretion of protein and pepsinogen by rabbit gastric mucosa in organ culture. 109 89

Gastric secretion was stimulated by intravenous infusion of 15 mug/kg/hr of pentagastrin before and 10 and 90 days after proximal gastric vagotomy in 16 duodenal ulcer patients. Postoperatively 15 ug/kg/hr of pentagastrin was also given in combination with 2 mug/kg/hr of carbacholine. Mean acid output in response to pentagastrin alone was reduced by 48 and 64 per cent at 10 and 90 days after the vagotomy, respectively. Mean pentagastrin-stimulated acid output and volume of gastric juice was significantly higher at 10 days than at 90 days after the operation. Mean pepsin output decreased also, but the decrease was not statistically significant. There was no significant effect of carbacholine on pentagastrin-stimulated acid output either at 10 or 90 days. Carbacholine increased pentagastrin-stimulated volume of gastric juice significantly at 10 but not 90 days postoperatively. The effect of carbacholine on pentagastrin-stimulated pepsin output was significant both 10 and 90 days after the vagotomy. Pepsin output in response to pentagastrin plus carbacholine 10 days after the operation was not significantly different from preoperative values. At 10 days postoperatively the increase in pentagastrin-stimulated volume of gastric juice by carbacholine was significantly greater than at 90 days. The corresponding differences of acid and pepsin outputs were not significant.
 ...
PMID:Decrease in gastric secretion during the first three months after proximal gastric vagotomy in duodenal ulcer patients. 109 30

Pepsin was found capable of splitting cycloota- and cyclodecapeptides cyclo (-L-leucyl-L-tyrosyl-glycln-), n=6 or 8. The 18-membered peptides cyclo(-L-leucyl-L-tyrosyl-glycyl4-) and cyclo(-L-leucyl-L-tyrosy-delta-aminovaleroyl2-) were found stable to the effect of pepsin. To study the kinectics of hydrolysis for tyrosine-containing substrates of pepsin, a method of isolation of the unsplit substrate using ion-exchange resins and quantitative spectrophotometric estimation by absortion of tyysis of cycoocta and cyclodecapeptides was characterized by Km and kcat values.
 ...
PMID:[Conformational aspects of peptide interaction with proteolytic enzymes. Pepsin-catalyzed hydrolysis of cyclic peptides, containing leucyl-tyrosine fragments]. 110 81

Patients who had cranial injuries and those who were less severely injured had a normal gastric acid output. Pepsin output decreased throughout the first 72 hours after trauma. Gastric juice protein output was slightly increased. Gastric mucosal cell renewal as estimated by gastric juice DNA was increased. Patients who were more severely injured and those with intra-abdominal trauma had markedly increased gastric acid, pepsin, and protein output after increased gastric mucosal cell exfoliation but a relatively decreased gastric mucosal cell renewal between 36 and 72 hours after trauma. It is concluded that the gastric mucosa must be protected by antacids and/or gastric aspiration before 24 hours after trauma and continued through at least 72 hours. This study supports the importance of acid-pepsin damage during gastric mucosal cell exfoliation and decreased renewal in trauma patients and indicates the timing and value of prophylactic treatment.
 ...
PMID:Prospective studies of gastric secretion in trauma patients. 110 89

The protective effects of passive immunization with two kinds of anti-glycoprotein D (anti-gD) monoclonal antibodies, having different antiviral activities, were investigated in murine herpetic keratitis. One monoclonal antibody, designated M1, had high virus-neutralizing antibody titers, along with undetectable levels of complement-dependent cytolysis (CDC) and antibody-dependent cellular cytotoxicity (ADCC); the other, designated M12, exhibited extremely low titers of virus-neutralization with high level of CDC and ADCC. When systemically administered 24 hours prior to virus inoculation to the cornea, both M1 and M12 almost completely prevented the development of stromal keratitis. The protective efficacy of both was observed to be dose-dependent. Pepsin-treated M1 retained its efficacy in suppressing stromal keratitis, whereas pepsin-treated M12 did not. When the administration of M1 and M12 were delayed, both provided significant (but less complete) protection, up to 24 hours after virus inoculation. These results suggest that both virus neutralization and CDC/ADCC play an important role in preventing virus growth in the corneal stroma during the early stage of corneal infection.
 ...
PMID:Protective effects of anti-glycoprotein D monoclonal antibodies in murine herpetic keratitis. 131 53

Expression of the cysteine proteinase cathepsin B and its physiological inhibitor cystatin C was analyzed in vitro in 1 human fibrosarcoma and 4 human colon carcinoma cell lines. Cystatin C antigen as well as cathepsin B activity were detected in the conditioned media of the 5 cell lines. The corresponding cell extracts expressed high levels of cathepsin B activity, whereas only trace amounts of cystatin C antigen could be found. Northern-blot analysis revealed the presence in the 5 cell lines of a 0.8-kb cystatin C mRNA transcript and 2 cathepsin B transcripts of 2.3 and 4.3 kb. Pepsin treatment of tumor-cell-released cathepsin B induced an average 7.3-fold increase in activity, indicating that the enzyme was mainly present as a latent form in conditioned medium. The pepsin-activated cathepsin B from one colon carcinoma cell line was further characterized using the cysteine proteinase inhibitors E-64, recombinant cystatin C, a cystatin-C-derived peptidyl inhibitor (Z-LVG-CHN2), and cathepsin-B-specific diazomethyl ketone inhibitors (Z-FT(OBzl)-CHN2, Z-FS(OBzl)-CHN2). This activity was totally neutralized by recombinant cystatin C, suggesting a potential for interaction between released extracellular cathepsin B and cystatin C. In vitro assays of degradation of extracellular matrix showed that cysteine proteinase inhibitors could decrease matrix degradation induced by pepsin-activated conditioned media. With colon cells, this inhibition was not observed, indicating a requirement for an extracellular activation of latent cathepsin B. Our data provide evidence that cystatin C and latent cathepsin B are both released extracellularly by colon carcinoma cells in vitro. They suggest that cystatin C and cathepsin B interactions may participate, in an as yet unelucidated way, in the modulation of the invasive phenotype of human colonic tumors.
 ...
PMID:Cystatin C and cathepsin B in human colon carcinoma: expression by cell lines and matrix degradation. 139 47

Pepsin successfully catalyzed the synthesis of several peptide derivatives from N-protected di- or tripeptides and amino acid or peptide esters or p-nitroanilides in dimethylformamide-water solutions at pH 4.6. An optimal substrates:pepsin ratio depended on the structure of starting peptides, especially their fit to the substrate binding sites of the enzyme. For hexapeptide Z-Ala-Ala-Phe-Leu-Ala-Ala-OCH3 formation, an equilibrium yield was attained at 1:3.10(5) enzyme-substrates ratio that indicated high efficiency of pepsin in synthesis reactions. In the course of the equilibrium peptide synthesis, pepsin gradually disappeared from the liquid phase due to its entrapment within a gel, formed by the hexapeptide product, while retaining its activity. The inclusion into the precipitate was not specific for pepsin, so far as inert proteins, lysozyme, ribonuclease A and carbonic anhydrase, when added to the reaction mixture, became also co-precipitated with the hexapeptide formed. It appears that co-precipitation of pepsin, an important factor limiting the enzyme efficiency, might be operative as well for other proteinases used to catalyze peptide synthesis.
 ...
PMID:Pepsin as a catalyst of peptide synthesis. Enzyme co-precipitation with emerging peptide products. 142 33


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>