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

Luteinizing hormone (LH) and follicle stimulating hormone (FSH) stimulated the accumulation of adenosine 3',5'-monophosphate (cAMP) within 30 minutes of addition to human testicular incubates. The phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine acted synergistically with FSH and to a lesser degree with LH to enhance cAMP accumulation. The findings indicate that cAMP accumulation may be involved in the mechanism of action of LH and FSH in the human testes, as has been proposed for rats. The prostaglandins (PG) PGE-1, PGE-2, PGA-1, and PGF-2-alpha stimulated cAMP levels at a concentration of 1/10,000 M in human testes. The E type prostaglandins were the most potent; they induced half-maximal stimulation of cAMP at 7/10,000,000 M.
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PMID:Stimulation of cyclic adenosine 3':5'-monophosphate accumulation in human testes in vitro by luteinizing hormone, follicle-stimulating hormone, and prostaglandins. 8 21

A peptide-containing extract (PE) from Helix nervous system modifies the endogenous bursting pattern of electrical activity in Helix neurone F-1. This effect is similar to that induced in neuron F-1 by certain phosphodiesterase inhibitors and cAMP derivatives. The PE, and the vertebrate peptide hormones vasopressin and oxytocin, also cause an accumulation of cAMP in Helix ganglia in vitro. The factor in the PE which causes the cAMP accumulation is destroyed by Pronase, is lost on dialysis, and is stable to boiling. In all these respects it is identical to the factor which causes the change in neuronal electrical activity. The PE also stimulates adenylate cyclase activity in a crude membrane fraction prepared from Helix ganglion homogenates. This stimulation is abolished by prior dialysis of the PE, or pretreatment of the PE with pepsin, but is not affected by boiling of the PE. Pepsin-treated PE has no effect on electrical activity in neuron F-1. The adenylate cyclase-stimulating activity of the PE, like the factor which modifies neurone F-1 electrical activity, elutes in the void volume of a Sephadex G-10 column. The included volume of this column contains a factor which inhibits PE modification of neuronal electrical activity, and also inhibits both basal and PE-stimulated adenylate cyclase activity. The data are consistent with the possibility that cAMP mediates the effects of the PE on electrical activity in molluscan neurones.
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PMID:Modulation of electrical activity and cyclic nucleotide metabolism in molluscan nervous system by a peptide-containing nervous system extract. 20 Mar 7

The effect of secretin on acid and pepsin secretion and gastrin release in the totally isolated vascularly perfused rat stomach was studied. With the phosphodiesterase inhibitor isobutyl methylxanthine (IMX) added to the vascular perfusate, baseline acid secretion was 4.7 +/- 1.1 (mean +/- S.E.M.) mumol/h and baseline pepsin output 1147 +/- 223 micrograms/h. Secretin significantly inhibited acid output to a minimum of 1.4 +/- 0.2 mumol/h at a concentration of 25 pM in the vascular perfusate (P less than 0.01). Pepsin output was not significantly different from baseline at any of the secretin doses tested. Threshold secretin concentration for acid inhibition was 5 pM. IMX stimulated gastrin output from 48 +/- 9 pM in the basal state to 95 +/- 13 pM after IMX (P less than 0.01). Secretin inhibited gastrin release only at the maximal dose of 625 pM, when gastrin concentration in the venous effluent decreased from 93 +/- 19 to 68 +/- 19 pM after secretin. Thus, in the totally isolated vascularly perfused rat stomach secretin in physiological concentrations inhibits acid secretion by a direct action on the acid secretory process and not via gastrin inhibition. The study also suggests that gastrin release at least in part is mediated via increased intracellular cAMP.
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PMID:The effect of secretin on acid and pepsin secretion and gastrin release in the totally isolated vascularly perfused rat stomach. 243 26

Pepsin is a potent proteolytic enzyme stored and secreted by chief cells in an inactive precursor form, pepsinogen. Its secretion is modulated by both cAMP and calcium-dependent mechanisms. Abnormalities in levels of pepsinogen and its various isozymogens have been linked clinically, epidemiologically, and experimentally to peptic ulcer disease and gastric carcinoma. The ulcerogenesis of pepsin stems from its ability to breach gastroduodenal mucosal barriers. Furthermore, certain isozymogens seems abundant and hyperactive in patients with peptic ulcer disease. The etiology and significance of low pepsinogen levels with disproportionate elevations of pepsinogen II and pepsin 5 in gastric cancer and its precursors is less clear. Further exploration of the patho-physiologic role of pepsin is likely to be of considerable importance in initiating further advances in the understanding and treatment of upper gastrointestinal disease.
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PMID:Pepsinogen. Prolate ellipsoid or unrecognized pathogen? 330 25

Both the triple-helical and denatured forms of nonfibrillar bovine dermal type I collagen were tested as substrates for the catalytic subunit of cAMP-dependent protein kinase in an in vitro reaction. Native, triple-helical collagen was not phosphorylated, but collagen that had been thermally denatured into individual alpha chains was a substrate for the protein kinase. Catalytic subunit of cAMP-dependent protein kinase phosphorylated denatured collagen to between 3 to 4 mol of phosphate/mol of (alpha 1(I)2 alpha 2(I). Pepsin-solubilized and intact collagens were phosphorylated similarly, as long as each was in a nonhelical conformation. The first 2 mol of phosphate incorporated into type I collagen by the protein kinase were present in the alpha 2(I) chain. The alpha 1(I) chain was only phosphorylated during long incubations in which the stoichiometry exceeded 2 mol of phosphate/mol of (alpha 1(I)2 alpha 2(I). Phosphoserine was the only phosphoamino acid identified in collagen that had been phosphorylated to any degree by the protein kinase. The 2 mol of phosphate incorporated into the alpha 2(I) chain were localized to the alpha 2(I)CB4 cyanogen bromide fragment. The catalytic subunit of cAMP-dependent protein kinase phosphorylated denatured pepsin-solubilized collagen with a Km of 8 microM and a Vmax of approximately 0.1 mumol/min/mg of enzyme. Denatured, but not triple-helical, type I collagen was also phosphorylated by cGMP-dependent protein kinase, although it was a poorer substrate for this enzyme than for the cAMP-dependent protein kinase. Collagen was not a substrate for phospholipid-sensitive Ca2+-dependent protein kinase. These results suggest the potential for nascent alpha chains of type I collagen to be susceptible to phosphorylation by cAMP-dependent protein kinase in vivo prior to triple-helix formation. Such a phosphorylation of collagen could be relevant to the action of cAMP to increase the intracellular degradation of newly synthesized collagen.
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PMID:In vitro phosphorylation of type I collagen by cyclic AMP-dependent protein kinase. 395 36

Prostaglandins of the A series have been reported to inhibit tumor cell growth and induce tumor cell differentiation by a yet unknown mechanism. We propose that these effects are due to the presence of a reactive alpha, beta-unsaturated carbonyl group (delta 10,11) in the cyclopentane ring of the PGA molecule. PGA was effective whereas PGB (sterically hindered alpha, beta-unsaturated carbonyl at delta 8, 12) and PGA conjugated to glutathione were ineffective. 15-Epi-PGA2 was as effective as PGA2 suggesting that the S absolute configuration of the 15-hydroxyl group is not essential. There was no correlation between generation of cAMP and inhibition of cell proliferation or induction of differentiation by various prostaglandins. The data suggest that PGA's and PGA-like compounds inhibit tumor cell growth and induce differentation because of the chemical reactivity of the alpha, beta-unsaturated carbonyl rather than hormonal activity of the prostanoid nucleus.
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PMID:Requirement of a reactive alpha, beta-unsaturated carbonyl for inhibition of tumor growth and induction of differentiation by "A" series prostaglandins. 403 34

In order to study mechanisms underlying selective enzyme release from human leukocytes during phagocytosis, the effects were studied of compounds which affect microtubule integrity or the accumulation of cyclic nucleotides. Human leukocytes selectively extrude lysosomal enzymes (beta-glucuronidase) from viable cells during phagocytosis of zymosan or immune complexes, or upon encounter with immune complexes dispersed along a non-phagocytosable surface such as a millipore filter. In each circumstance, lysosomal enzyme release was reduced by previous treatment of cells with pharmacological doses of drugs which disrupt microtubules (e.g. 10(-3)-10(-5) M colchicine) or with agents which affect accumulation of adenosine 3'5'-monophosphate (cAMP) (e.g. 10(-3) M cyclic nucleotides and 2.8 x 10(-4)-2.8 x 10(-6) M prostaglandin E (PGE) and A (PGA) compounds). Preincubation of cells with 5 microg/ml cytochalasin B resulted in complete inhibition of zymosan ingestion, but not of adherence of zymosan particles to plasma membranes or selective enzyme release. In this system, in which enzyme release was independent of particle uptake, preincubation of cells with colchicine, vinblastine, dibutyryl cAMP, or PGE(1) also reduced extrusion of lysosomal enzymes. When cell suspensions were incubated with membrane-lytic crystals of monosodium urate (MSU), cytoplasmic as well as lysosomal enzymes were released with subsequent death of the cells. However, enzyme release followed phagocytosis of crystals (as measured by enhanced C-1 oxidation of glucose) and was due to "perforation from within" of the lysosomal membrane, rather than lysis by crystals of the plasma membrane. Enzyme release after MSU ingestion was also reduced when cells were treated with pharmacological doses of the test agents. When cells were killed by Triton X-100, acting on the plasma membrane, C-1 oxidation of glucose was abolished and enzyme release could not be inhibited pharmacologically. These observations suggest that lysosomal enzyme release from human phagocytes can be an active process which accompanies plasma membrane stimulation, is independent of cell death, and may be controlled by cyclic nucleotides and agents which affect microtubules.
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PMID:Mechanisms of lysosomal enzyme release from human leukocytes. I. Effect of cyclic nucleotides and colchicine. 412 73

The effect of omeprazole, an inhibitor of the parietal cell H+-K+-ATPase, on pepsin and acid secretion was studied in an in vitro perfused whole mouse stomach model. Omeprazole inhibited basal and dibutyryl cAMP (DBcAMP)- and histamine-stimulated acid secretion in a dose-dependent fashion with a maximally effective dose of 10(-4) M. At the same time, omeprazole induced a dose-dependent increase of unstimulated pepsin release. This increase was not affected by pretreatment with 10(-3) M atropine or 10(-4) M cimetidine. It was, however, inhibited by preincubation with 10(-4) M carbonyl cyanide m-chlorophenylhydrazone (CCCP). Pepsin secretion after maximally effective doses of histamine or DBcAMP was not affected by 10(-4) M omeprazole. In a concentration of 10(-5) M, the effect of omeprazole was additive to the effect of submaximal concentrations of carbachol and histamine. NaSCN and imidazole mimicked the effect of omeprazole on acid secretion, but pepsin release was only stimulated with 10(-2) M imidazole. Another weak base, benzylamine, stimulated acid and pepsin in parallel. Luminal perfusion with solutions of high K+ concentration did not enhance basal pepsin release. The dissociated response of acid and pepsin secretion indicates that omeprazole does not act selectively on the parietal cell. The stimulation of pepsin secretion might be related to the weak base properties of the compound.
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PMID:Dissociated response of acid and pepsin secretion to omeprazole in an in vitro perfused mouse stomach. 608 88

Prostaglandins (PGs) are bioregulatory substances and are widely distributed in a variety of tissues. Numerous facts have been described in relation to cancer biology with PGs. The purpose of our study lies in the creation of anti-tumor PGs. We have described that PGD2 has strong cell growth inhibitory activity; furthermore, we discovered that PGJ2, 9-deoxy-delta 9-PGD2, has 3 times stronger activity than the mother compound, PGD2. In vivo experiments showed that only PGA2 and PGJ2 exert antitumor activity. Thus, cyclopentenone ring structure in PG seems to be an essential moiety for cytotoxicity of PG. On the basis of the above facts, we propose tha name of antineoplastic PGs for PGA and PGJ derivatives which have cyclopentenone ring. Recently, we developed several antineoplastic PGs which showed IC50 value less than 0.3 microgram/ml against L1210 leukemia cells, and these compounds also showed antitumor activity against Ehrlich ascites tumor in vivo comparable to that of cyclophosphamide. The action mechanism seems to be in its alkylation activity of the cyclopentenone structure and not in receptor-cAMP route. Spectrum of anti-tumor activity and its toxicity in vivo are now under investigation. In this brief review, mainly our recent approaches in this field are discussed.
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PMID:[Development of antineoplastic prostaglandins]. 657 12

Human gastric mucosa contains aspartic proteinases that can be separated electrophoretically on the basis of their physical properties into two major groups: Pepsinogen I (PGA, PGI); and Pepsinogen II (PGC, PGII). Pepsinogens consist of a single polypeptide chain with molecular weight of approximately 42,000 Da. Pepsinogens are mainly synthesized and secreted by the gastric chief cells of the human stomach before being converted into the proteolytic enzyme pepsin, which is crucial for the digestive processes in the stomach. Pepsinogen synthesis and secretion are regulated by positive and negative feed-back mechanisms. In the resting state pepsinogens are stored in granules, which inhibit further synthesis. After appropriate physiological or external chemical stimuli, pepsinogens are secreted in the stomach lumen where hydrochloric acid, secreted by the parietal cells, converts them into the corresponding active enzyme pepsins. The stimulus-secreting coupling mechanisms of pepsinogens appear to include at least two major pathways: one involving cAMP as a mediator, the other involving modification of intracellular Ca(2+)concentration. Physiological or external chemical stimuli acting through the intracellular metabolic adenyl cyclase are more effective in inducing ' de novo ' pepsinogen synthesis than those acting through intracellular Ca(2+). The activation of protein kinase C (PK-C) would appear to be involved in regulatory processes. The measurement of pepsinogens A and C in the serum is considered to be one of the non-invasive biochemical markers for monitoring peptic secretion and obtaining information on the gastric mucosa status of healthy subjects. Recently, pepsinogen measurements have been used as an effective biochemical method for evaluating and monitoring patients with gastrointestinal diseases and for checking the effects of drug treatment. The level of PGA in the serum is always high in normal gastritis, while in atrophic gastritis it is always low. In both cases the PGC level in the serum is high. In most gastrointestinal pathologies the ratio between the PGA/PGC decreases. Various reports concerning hormone and/or enzyme modification as well as gastrointestinal distress in the case of long distance exercise have been reported. It has been suggested that the origin of the gastrointestinal distress experienced by long distance runners is a transient ischaemia of the gastric mucosa; it is also suggested that a hypobaric-hypoxic environment could contribute to induce gastric mucosa necrosis. Interrelation between gastrointestinal distress, hypobaric-hypoxic environment and modifications of PGA and PGC, gastrin and cortisol was evaluated in 13 athletes after a marathon performed at 4300 m. Gastrointestinal symptoms occurred in approximately 40% of the athletes. After the race the athletes showed a significant increase of gastrin and cortisol, while the ratio between PGA/PGC decreased. No relationship was observed between gastrointestinal symptoms and hormonal changes after the race. A control group of five subjects, who had been exposed to the same environmental conditions, showed no gastrointestinal or hormonal alteration. Conversely, control subjects presented a significant decrease of cortisol related to the circadian rhythm. The same incidence of gastrointestinal symptoms at high altitude and at sea level and the absence of pathological alteration of PGA and PGC in the serum of the athletes indicates that running a marathon and living for 6 days at 4300 m does not induce gastric mucosa necrosis. Cortisol and gastrin alteration observed in the athletes at this altitude would seem to be related to an activation of the mesopontine and forebrain structures involved in the behavioural and metabolic integration of the autonomic control and arousal and psychophysical-exercise stress. 2000 Academic Press@p$hr
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PMID:Pepsinogens: physiology, pharmacology pathophysiology and exercise. 1067 78


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