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)

In patients with peptic ulceration, both vagal stimulation by insulin hypoglycaemia and stimulation by pentagastrin cause pepsin 1 to be secreted into gastric juice. There is a secretory threshold for pepsin 1, below which only pepsins 3 and 5 are secreted. Pepsin 1 accounts for an increasing proportion of the total peptic activity/ml of gastric juice as the total activity increases. Higher concentrations of pepsin 1 in the basal gastric secretion occurred significantly more frequently in patients with duodenal ulcer than with gastric ulcer. In these patients there may be an increased 'background' secretory drive.
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PMID:Pepsin 1 secretion in chronic peptic ulceration. 677 16

1. The effect of i.v. administration of prostaglandin (PG) E(2) (10-40 mug kg(-1) h(-1)), 16,16-dimethyl PGE(2) (0.1-0.5 mug kg(-1) h(-1)), PGE(1) (16-20 mug kg(-1) h(-1)), PGA(1) (5-11 mug kg(-1) h(-1)) and PGF(2alpha) (40 mug kg(-1) h(-1)) on the relationship between [H(+)] and flow of gastric juice during stimulation of gastric secretion by pentagastrin was investigated in conscious cats prepared with cannulated gastric fistulae.2. A- and E-type prostaglandins significantly reduced pentagastrin-stimulated acid output. This inhibition was associated with a reduction of the [H(+)] of the gastric juice such that the [H(+)] observed at any flow rate tended to be lower than the normal range observed with pentagastrin alone. With the highest doses of these prostaglandins the mean [H(+)] values were well below the normal range with pentagastrin alone.3. At the dose tested, PGF(2alpha) had little effect on acid output, and did not alter the relationship between [H(+)] and gastric flow.4. There is a linear relationship between acid output and gastric flow and this relationship is similar during stimulation of gastric secretion by pentagastrin, histamine or insulin. Gastric acid inhibitory doses of cimetidine, atropine and somatostatin did not alter this relationship. In contrast the A- and E-type prostaglandins displaced this relationship to the right of the normal line observed with the acid stimulants alone. A- and E-type prostaglandins reduced the slope of the line relating acid output and gastric flow from approximately 150-170 muequiv/ml(-1) to approximately 100-120 muequiv ml(-1), this being taken as evidence of dilution of the parietal H(+) secretion with a non-parietal secretion.5. The volume of non-parietal gastric secretion was calculated as the gastric flow at zero acid output by extrapolation of linear plots of acid output versus gastric flow. Unstimulated gastric flow measured directly was 0.75 ml 15 min(-1). The calculated non-parietal flow was in the range 0.52-0.90 ml 15 min(-1) during stimulation of gastric secretion with pentagastrin, histamine and insulin, and inhibition of pentagastrin-stimulated acid secretion with cimetidine, atropine and somatostatin. PGE(2) (1.51 ml 15 min(-1)) and 16,16-dimethyl PGE(2) (1.20 ml 15 min(-1)) nearly doubled the calculated non-parietal flow.6. These data demonstrate that gastric acid inhibitory doses of A- and E-type prostaglandins can reduce the [H(+)] in the bulk fluid of the gastric lumen during stimulation of acid secretion. The data provide evidence that these prostaglandins stimulate a non-parietal component of gastric secretion. This might be gastric bicarbonate and mucus secretion.
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PMID:Prostaglandins alter the relationship between gastric hydrogen ion concentration and flow: evidence for stimulation of non-parietal secretion in the cat. 694 8

It is known that some metabolic disturbances may modify the progression of renal disease including primary glomerulonephritis, but the role of purines in this process is still unknown. To investigate this, 13 untreated patients with primary glomerulonephritis were followed up for a mean of 17.6 months to analyze the changes in proteinuria and glomerular filtration rate. On entering the study, each patient was given an oral glucose tolerance test and an oral fructose load test. The areas under the glucose (PGA), insulin (PIA) and uric acid (PUAA, post-fructose) curves were calculated. Glomerulonephritic patients were found to have a statistically higher response to fructose than controls (782 +/- 219 vs 518 +/- 154, P < 0.005). Multiple regression analysis showed that PGA, PIA and PUAA were independently related to changes in proteinuria and glomerular filtration rate during the natural course of the disease. This preliminary study suggests that purine metabolism may modulate the progression of renal disease in proteinuric patients.
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PMID:The relationship between insulin, glucose and serum uric acid and their contribution to the progression of renal damage in patients with primary glomerulonephritis. 895 28

Arterial hypertension-related renal damage is an increasingly common problem recently, because approximately 25% of patients currently treated with dialysis were hypertensive before renal replacement therapy was started. Hypertension is also known as a metabolic disease, while carbohydrate, purine and lipid disturbances are the features of this syndrome. On the other hand, the progression of renal disease depends on the extent of tubulointerstitial injury. For this reason, we undertook a study to evaluate the relationship between excretion of the markers of tubular damage (NAG) and some parameters of carbohydrate, purine and lipid metabolism in untreated essential hypertension. Both healthy volunteers (n = 15) aged 32. 6+/-7.8 and essential hypertensives (n = 25) aged 37.24+/-11.39 underwent the same tests. These tests were performed at 2-day intervals: intravenous glucose tolerance test with 0.5 g/kg b.w. as 40% glucose solution and oral fructose load test with 1.0 g/kg b.w. Area under glucose curve (GA) and serum uric acid post-fructose (PUAA) were calculated. Fasting: insulin, total cholesterol and LDL, triglycerides, free fatty acids (FFA) and urine excretion of NAG, albumin were determined. Glomerular filtration rate was estimated as creatinine clearance. Hypertensives showed statistically higher BMI (p<0.007), NAG (p<0.02), total cholesterol (p<0.01), LDL (p<0.007), FFA (p<0.007), insulin (p<0.01), PGA (p<0.01) and PUAA (p<0.03). NAG excretion correlated positively with WHR (r = 0.40), MAP (r = 0.47) and PUAA (r = 0.47) in hypertensives only. We presume that tubular injury at an early stage of renal damage in patients with essential hypertension could be a part of metabolic syndrome X.
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PMID:Hypertensive nephropathy - an increasing clinical problem. 1020 62

Purification of pepsinogen B from dog stomach was achieved. Activation of pepsinogen B to pepsin B is likely to proceed through a one-step pathway although the rate is very slow. Pepsin B hydrolyzes various peptides including beta-endorphin, insulin B chain, dynorphin A, and neurokinin A, with high specificity for the cleavage of the Phe-X bonds. The stability of pepsin B in alkaline pH is noteworthy, presumably due to its less acidic character. The complete primary structure of pepsinogen B was clarified for the first time through the molecular cloning of the respective cDNA. Molecular evolutional analyses show that pepsinogen B is not included in other known pepsinogen groups and constitutes an independent cluster in the consensus tree. Pepsinogen B might be a sister group of pepsinogen C and the divergence of these two zymogens seems to be the latest event of pepsinogen evolution.
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PMID:Primary structure, unique enzymatic properties, and molecular evolution of pepsinogen B and pepsin B. 1214 55

A miniaturized pepsin reactor was prepared inside a fused-silica capillary (i.d. 75 microm) by coating a pepsin-containing gel on a photopolymerized porous silica monolith. The pepsin-encapsulated film was prepared by a sol-gel method. The sol-gel reaction was optimized so that the sol solution containing pepsin forms a thin film on the photopolymerized sol-gel (PSG) monolith that was initially fabricated at the inlet of the capillary. Pepsin was encapsulated into the gel matrix without losing its activity. The large surface area of the PSG monolith enabled the immobilized pepsin to achieve a high catalytic turnover rate, and the porous nature of the PSG promotes penetration of large molecular proteins into the column. The immobilized pepsin-digested peptides and proteins, and the resulting mixture of peptide fragments, could be directly separated in the portion of the capillary where no PSG monolith exists. The durability and repeatability of the fabricated pepsin-coated column was tested and found to be satisfactory. An acidic solution consisting of 0.5 M formic acid was used as the running buffer, because it suppresses the adsorption of proteins or peptides on the inner surface of the capillary as well as enables direct connection of the output of the capillary electrophoresis column to a mass spectrometer. The on-line digestion of insulin chain beta and lysozyme provides identification of the proteolytic peptides. Recovery was achieved for 100% of the insulin chain beta amino acid sequence and 73% of the lysozyme amino acid sequence.
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PMID:Integration of on-line protein digestion, peptide separation, and protein identification using pepsin-coated photopolymerized sol-gel columns and capillary electrophoresis/mass spectrometry. 1505 49

The limited proteolysis approach was used to analyze the conformational features of human growth hormone (hGH) under acidic solvent conditions (A-state). Pepsin was used as the proteolytic probe because of its poor substrate specificity and its activity at low pH. Limited proteolysis of hGH in its A-state results in a selective cleavage of the Phe44-Leu45 peptide bond, leading to the production of fragments 1-44 and 45-191. The two fragments were isolated in homogeneous form for studying their conformational properties by means of spectroscopic methods. Fragment 1-44 was shown to retain little secondary and tertiary structure at neutral pH, while fragment 45-191 independently folds into a highly helical secondary structure. In particular, we have shown that the two peptic fragments are able to associate into a stable and native-like hGH complex 1-44/45-191. Our proteolysis data indicate that in acid solution hGH adopts a partly folded state characterized by a local unfolding of the first minihelix (residues 38-47) encompassing the Phe44-Leu45 peptide bond. Of interest, hGH has both insulin-like and diabetogenic effects. Two fragments of hGH occur in vivo and exert these two opposite activities, namely, fragment 1-43 showing an insulin-potentiating effect and fragment 44-191 showing a diabetogenic activity. The results of this study suggest that the conformational changes of hGH induced by an acidic pH promote the generation of the two physiologically relevant fragments by proteolytic processing of the hormone. Although pepsin cannot be the enzyme responsible for the in vivo processing of the hormone, we propose that limited proteolysis of hGH at low pH is physiologically relevant, since the hormone is exposed to an acidic environment in the cell. This study reports for the first time the analysis of the conformational features of the two individual functional domains of hGH and of their complex.
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PMID:Limited proteolysis of human growth hormone at low pH: isolation, characterization, and complementation of the two biologically relevant fragments 1-44 and 45-191. 1515 90

Within this study, the potential of three clinically relevant microproteins (SE-AG-AZ, SE-EM and SE-EP) with cystine-knot architecture as pharmacophoric scaffolds for oral peptide delivery was investigated. Cystine-knot microproteins (CKM) were analysed regarding their stability towards the most important gastrointestinal secreted and membrane bound proteases in physiological concentrations. In addition, their permeation behaviour through freshly excised rat intestinal mucosa as well as important parameters such as aggregation behaviour, stability in rat plasma and isoelectric point were evaluated and compared to the properties of the model peptide drugs bacitracin and insulin. Aggregation studies indicate that under physiological conditions between 25 and 70% of the CKMs occur as monomers, whereas the rest forms di- and trimers. Pepsin and elastase cause no or only minor degradation to CKMs, whereas trypsin and chymotrypsin degrade CKMs extensively. Removing the theoretical chymotrypsin cleavage site from a CKM, however, led to stabilization towards this protease. Two of the three evaluated CKMs are stable against membrane bound proteases. P(app) values were determined to be 5.96 +/- 0.98 x 10(-6) and 6.63 +/- 0.47 x 10(-6) cm/s. In conclusion, this study indicates that CKM are promising novel pharmacophoric scaffolds for oral peptide delivery.
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PMID:The potential of cystine-knot microproteins as novel pharmacophoric scaffolds in oral peptide drug delivery. 1675 27

Insulin-mimetic vanadyl-poly(gamma-glutamic acid) complex, VO-gamma-PGA, is proposed as a novel drug delivery system for treating type 1 diabetic animals. The structure of VO-gamma-PGA in solution as well as in solid state was analyzed by electronic absorption, infra-red, and electron spin resonance spectra, and proposed that the equatorial coordination mode of VO(2+) is in either carboxylate(O)-VO-(OH(2))(3) or 2 carboxylate(O(2))-VO-(OH(2))(2). In vitro insulin-mimetic activity, metallokinetic feature in the blood of healthy rats, and in vivo normoglycemic effect of the complex prepared in solution were evaluated in streptozotocin(STZ)-induced type 1 diabetic mice, and these effects were compared with those of a solution containing only VOSO(4) as a positive control. The in vitro insulin-mimetic activity of VO-gamma-PGA was examined by determining both inhibition of free fatty acid (FFA) release and glucose uptake in isolated rat adipocytes, in which the concentration of VO-gamma-PGA for 50% inhibition of FFA release was significantly lower than that of VOSO(4). Metallokinetic study suggested that the bioavailability of VO-gamma-PGA complex was much higher than that of VOSO(4). The complex showed a significant hypoglycemic activity within at least 4h after a single oral administration, the effect being sustained for at least 24h. Furthermore, VO-gamma-PGA normalized the hyperglycemia in STZ-mice within 3 days when it was given orally at doses of 5-10mgVkg(-1) body mass for 16 days. The improvement in diabetes was also supported by the results on oral glucose tolerance test, HbA(1c) levels, and blood pressure.
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PMID:A novel drug delivery system for type 1 diabetes: insulin-mimetic vanadyl-poly(gamma-glutamic acid) complex. 1682 5

Nanoparticles (NPs) composed of chitosan (CS) and poly(gamma-glutamic acid) (gamma-PGA) were prepared by a simple ionic-gelation method for oral insulin delivery. Fourier transform infrared (FT-IR) spectra indicated that CS and gamma-PGA were ionized at pH 2.5-6.6, while X-ray diffractograms demonstrated that the crystal structure of CS was disrupted after it was combined with gamma-PGA. The diameters of the prepared NPs were in the range of 110-150 nm with a negative or positive surface charge, depending on the relative concentrations of CS to gamma-PGA used. The NPs with a positive surface charge (or shelled with CS) could transiently open the tight junctions between Caco-2 cells and thus increased the paracellular permeability. After loading of insulin, the NPs remained spherical and the insulin release profiles were significantly affected by their stability in distinct pH environments. The in vivo results clearly indicated that the insulin-loaded NPs could effectively reduce the blood glucose level in a diabetic rat model.
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PMID:Preparation and characterization of nanoparticles shelled with chitosan for oral insulin delivery. 1720


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