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. The serum gastrin level, gastric mucosal blood flow and acid secretion from the canine Heidenhain pouch have been measured in response to the introduction of bovine serum albumin, pepsin-digested albumin, an amino acid mixture, liver extract and mannitol used as control. 2. Distention of the Heidenhain pouch with mannitol or albumnin at pH 5-0 produced a similar pressure-related increase of acid secretion reaching a peak of only 10 percent of the maximal response to histamine. Pepsin-digested albumin was capable of producing larger acid outputs than undigested albumin. The highest acid output, attaining about 80 percent of the maximal response to histamine, was obtained with liver extract both before and after exhaustive dialysis to remove all the amino acids and short peptide fragments. An amino acid mixture containing all essential amino acids was also found to stimulate acid secretion but a lesser degree than liver extract. 3. This concluded that it is not the intact protein but the products of its digestion, the polypeptides and free amino acids, which are potent chemical stimulants of acid secretion from the oxyntic gland area. Since the serum gastrin level was not changed during acid secretion induced by peptic digests bathing the oxyntic gland area, the mechanism of chemical stimulation appears to be gastrin-independent. 4. The response to chemical stimulation by peptic digests can be greatly potentiated by combining this with distention of the oxyntic gland area. Topical application of xylocaine or atropine causes a marked decrease of Heidenhain pouch response to peptic digests, suggesting a possible neural reflex component in the mechanism of chemical stimulation of the oxyntic gland area. 5. When the pH of the liver extract in the Heidenhain pouch was gradually decreased in sequential order from 5-0 to 1-0, this resulted in a pH-related decrease in acid secretion and in the mucosal blood flow falling to the basal level at pH 1-0. Exogenous secretion given in graded doses from 0-5 to 8-0 u./kg. hr caused a small but dose-related inhibition of acid response to liver extract accompanied by a decrease of mucosal blood flow but without any significant change in the serum gastrin level. 6. The results indicate that the chemical stimulation of the oxyntic gland area by peptic digests is capable of inducing acid secretion by a local, gastrin-independent, partially neural reflex mechanism; sensitive to pH, pressure and secretin.
 ...
PMID:Chemical stimulatory mechanism in gastric secretion. 23 20

Albumin magnetic microparticles reversibly adsorb thyroxine. They quickly establish equilibrium allowing time and temperature independent measurements in T4 radioassays. We used these particles to compare the efficiency of NaOH, HCl, pepsin, sodium trichloroacetate, and 8-anilino-1-naphthalene sulfonic acid to release 125I-T4 from serum, T4-free serum and human serum albumin. We found that the efficiency of the reagents to extract 125I-T4 depended on the concentration and type of proteins to which the labelled hormone was bound. Pepsin was the most effective reagent and we utilized it for a T4 radioimmunoassay, in which albumin magnetic microparticles were used to separate free from bound hormone. We also utilized the particles in a T4 non-immune radioassay. Both assays accurately measured total serum T4, however the radioimmunoassay was simpler, less dependent on protein content of serum, required a smaller serum sample and provided slightly higher T4 values. We describe a magnetic rack which allows simultaneous handling of fifty individual tubes with an intra-assay C.V. of 2.1% for the radioimmunoassay and 2.3% for the non-immune assay and an inter-assay C.V. of 3.1%, respectively.
 ...
PMID:Immune and non-immune T4 radioassays utilizing albumin magnetic microparticles. 63 18

We have investigated the uptake and subsequent metabolism of the prostaglandins (PGs) PGE1, PGA1, and PGB1 by rat, guinea pig and rabbit isolated perfused lungs (IPL). Significant species differences were not observed in the uptake or metabolism of any PG on passage through the IPL. However, differences in the uptake of PGA1 and PGB1 and in the metabolism of PGA1 were observed with a given species when the composition of the perfusion medium was varied. The IPL removed minimal amounts (less than 20% of the supply rate) of PGA1, and PGB1 from the circulation when the perfusate contained 4.5% bovine serum albumin (BSA). In the absence of BSA, however, both PGA1 and PGB1 were substantially removed from circulation (approximately 53% of the supply rate) and PGA1 was also metabolized. The composition of the perfusate had no effect on the uptake and metabolism of PGE1 which was always taken up and metabolized to a greater extent than was PGA1 and PGB1. Thus, the apparent species differences previously reported for the pulmonary biotransformation of PGA can result from differences in the perfusion medium used. Our data suggest that both plasma protein binding and a transport system play important roles in determining the selectively of the uptake of PGs by the lung.
 ...
PMID:Uptake and metabolism of prostaglandins by isolated perfused lung: species comparisons and the role of plasma protein binding. 89 17

The binding of tritiated prostaglandins (PGA1, PGE1, PGF2alpha, and PGE2) to human and bovine serum albumins was studied by equilibrium dialysis and batchwise gel equilibration with Sephadex G-25. During equilibrium dialysis (36 hours, 4 degrees C), about half of the PGEs, but not PGA and PGF2alpha, were transformed into dehydration products; by contrast, equilibration of the prostaglandins was attained in less than a half-hour by the batchwise use of Sephadex G-25 at 25 degrees C, with no detectable ligand instability. The values of the apparent association constants for albumin-prostaglandin interactions were inversely related to the protein concentration in the assay systems. "True" apparent association constants (NKo) were measured by extrapolation to zero protein concentration. The NKo values were estimated to be 9.4 X 10(4), 2.7 X 10(4), 9 X 10(3) and 6 X 10(3) M-1 for the interaction of human serum albumin with PGA1, PGE1, PGF2alpha and PGE2, respectively. Very similar values were found for the corresponding bovine serum albumin-Prostaglandin interactions. When comparable, the data obtained by both methods were in excellent agreement. Our results were also in agreement with published values for PGA1 and PGF2alpha, both of which are relatively stable in neutral aqueous phase. Batchwise gel equilibration appears to be a useful method, if thermodynamically valid data are desired in the presence of possible ligand and/or "receptor" instability. We conclude that albumin binding probably affords circulating PGA1 a modest protection from its clearance mechanisms.
 ...
PMID:Prostaglandin-macromolecule interactions. I. Noncovalent binding of prostaglandins A1, E1, F2alpha, and E2 by human and bovine serum albumins. 94 73

Callus formation in the periosteal bone interface in response to bone morphogenetic protein (BMP) and associated bone matrix noncollagenous proteins (BMP/NCP) was investigated in mature adult rabbits. For controls byproducts of BMP/NCP purification, bone marrow, eight nonskeletal tissues, purified matrix gamma-carboxyglutamic acid-rich protein (MGP), and a composite of BMP/NCP and polylactic-polyglycolic acid polymer (PLA/PGA) were also implanted in the periosteal bone interface. Quantitative microcomputer image analysis and histologic studies were performed three weeks after the implantation. BMP/NCP and bone marrow or BMP/NCP implanted over a single drill hole into the marrow cavity produced three times more new bone than the bone marrow alone. BMP/NCP alone produced twice as much new bone as bone marrow alone. Control implants of bovine serum albumin or purified MGP produced no new bone. Autogeneic minced muscle and ten nonskeletal tissue controls produced little or no bone formation. Even at one-fifth of the dose of BMP/NCP, a composite of PLA/PGA incorporating BMP/NCP showed almost the same amount of new bone as BMP alone. Histologically, the response to BMP/NCP consisted of an external callus of calcifying cartilage and woven bone. The response to subperiosteal implants of BMP/NCP or BMP/NCP with bone marrow or with minced muscle occurred with the same sequence of developmental events as seen either in embryonic skeletogenesis or in fracture callus.
 ...
PMID:Induction of callus formation by implants of bone morphogenetic protein and associated bone matrix noncollagenous proteins. 318 May 78

The effects of ATP, vanadate, and molybdate on cathepsin D-catalyzed hydrolysis of proteins and peptides were examined. Hydrolysis of bovine serum albumin, hemoglobin, parathyroid hormone, and a synthetic octapeptide was activated by ATP. Degradation of the protein substrates all had similar ATP concentration dependence, but the magnitude of the activation varied. Kinetic constants for ATP activation were obtained with a synthetic substrate. ATP increased kcat from 0.4 to 2 s-1 but did not change KM. Kact for ATP was 800 microM. Studies with pepstatin-Sepharose confirm that ATP does not alter the substrate binding site on cathepsin D. Pepsin, a homologous aspartate protease, was not activated by ATP. It was also found that vanadate and molybdate inhibit cathepsin D-catalyzed proteolysis. However, this inhibition was dramatically dependent on substrate concentration and was eliminated at high substrate. Hydrolysis of the synthetic peptide was not inhibited at concentrations of molybdate below 50 microM, and above this concentration the peptide precipitated. Protein substrates were also found to precipitate in the presence of molybdate. The ATP dependence of the enzyme was not altered by molybdate or vanadate. These results suggest that inhibition by vanadate and molybdate is related to interactions with the substrate rather than with cathepsin D. It is concluded that ATP activation of cathepsin D may play a physiological role in regulation of proteolysis in lysosomes, but that vanadate and molybdate inhibition of lysosomal proteolysis does not establish ATP dependence.
 ...
PMID:Effects of ATP, vanadate, and molybdate on cathepsin D-catalyzed proteolysis. 389 55

Antibodies to the (PGA) prostaglandin A were produced in rabbits immunized with a conjugate of PGE2 covalently linked to (BSA) bovine serum albumin by reaction with carbodiimide reagent. A radioimmunoassay was developed using dextran-coated charcoal to separate the free from antibody bound PGA1-3H. The sensitivity of the method was found to be 100 picograms/ml of plasma. Ethyl acetate was used for extraction of plasma and the various classes of PGs were separated by silicic acid column chromatography. Recovery of PGA1-3H throughout the entire procedure was 65-75%. The antibody showed progressively decreasing affinity to PGA2, PGA1, PGE2, PGE1, PGB2, and PGF2alpha, respectively. The mean plasma PGA level in adult males (N=13) was found to be 1.39 + or - 0.55 ng/ml, and 1.62 + or - 0.52 ng/ml in adult females (N=7). Corresponding plasma and serum samples were found to give essentially similar results. Plasma PGA levels in adult males treated with indomethacin for rheumatoid arthritis were 0.18 + or - 0.15 ng/ml (P 0.001 in comparison with the normal adult males). This method is sufficiently sensitive, precise, and rapid to allow the routine estimation of the PGAs in biological samples.
 ...
PMID:Radioimmunoassay of the A prostaglandins. 466 56

1. With the aid of a coupled system involving glutathione reductase, the reaction of glutathione with the disulphide bonds of purified proteins has been studied. 2. Bovine serum albumin, conalbumin, lysozyme, trypsin inhibitors from egg white, lima bean and soya bean either did not react with glutathione or reacted only slightly. With these proteins reactivity was markedly increased by limited proteolysis. 3. Bovine and human gamma-globulins, fibrinogen and beta-lactoglobulin exhibited some reactivity (less than 15%) with glutathione and again this was increased by limited proteolysis. Pepsin, trypsin and chymotrypsin exhibited greater reactivity than the proteins previously mentioned. Di-isopropylphosphoryl-chymotrypsin exhibited less reactivity than chymotrypsin, suggesting that autolysis under the experimental conditions used contributed towards the reactivity of this protein. Proteolysis also increased the reactivity of these proteins. The three disulphide bonds of insulin were reduced by glutathione. 4. Above 35 degrees the disulphide bonds of serum albumin show a progressive increase in reactivity and at 55 degrees half of the bonds become accessible to glutathione. 5. From the results obtained with the proteins investigated, the conclusion reached is that the disulphide bonds of native proteins are structurally protected and do not react with glutathione under physiological conditions.
 ...
PMID:The reactivity of the disulphide bonds of purified proteins in relationship to primary structure. 486 Apr 70

The effect of amino acids and other chemicals of intragastric perfusion on pepsin secretion was studied in anaesthetized rats. Irrigation of the stomach with glycine caused concentration-dependent increase in pepsin output, but not in acid output. Pepsin stimulatory effect was decreased by an increase of the carbon chain between the amino group and carboxyl group of glycine and by transposing the amino group from alpha- to gamma-position in amino-n-butyric acid. Acidification of perfusate, a local irrigation of lidocaine and an intravenous infusion of atropine reduced but did not abolish the pepsin response to chemical stimulation. Since serum gastrin level was not changed from basal levels during pepsin secretion induced by amino acids, the mechanism of chemical stimulation appears to be gastrin-independent. The comparison of the secretagogue activity of amino acids shows that glycine exhibited the strongest stimulation of pepsin output, reaching 208% of the response to tetragastrin at the dose of 8 microgram/kg/hour. All other amino acids tested were found to stimulate pepsin secretion, whereas bovine serum albumin and hydrochloric acid were inert in this respect. The result indicates that the chemical stimulation of the stomach by amino acids is capable of inducing pepsin secretion by a local, gastrin-independent mechanism sensitive to pH and related to the molecular configuration of amino acids.
 ...
PMID:Effect of topical application of amino acids on gastric pepsin secretion in the rat. 678 43

Three cows and 2 sheep were passively immunized against prostaglandin (PG) F on Day 16 and Days 13-15 of the oestrous cycle respectively. The PGF antiplasma was raised in ovariectomized ewes against a PGF-2 alpha-bovine serum albumin complex and showed 100%, 12.5%, 0.3%, less than 0.05% and less than 0.01% cross-reactivity with PGF-2 alpha, PGE-2, PGA-2, PGB-2 and arachidonic acid, respectively. Control animals were given an equivalent amount of ovariectomized ewe plasma. In all passively immunized animals there was evidence of a persistent corpus luteum as indicated by plasma progesterone concentration and the failure of the animals to return to oestrus until at least 29 days after treatment. These data are consistent with previous proposals that PGF-2 alpha is the uterine luteolytic factor in sheep and cattle.
 ...
PMID:Prolongation of the oestrous cycle in cows and ewes after passive immunization with PGF antibodies. 719 12


1 2 3 4 Next >>