Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P17174 (aspartate aminotransferase)
 14,872 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We describe a column-chromatographic method for separating the mitochondrial and cytoplasmic isoenzymes of aspartate aminotransferase in human serum. Bed height of the ion exchanger, pH, and salt concentrations in the eluting buffers are shown to be variables affecting the separation of the isoenzymes. Under the optimized conditions selected for this study, a 30% increase in volume was observed in one fraction, associated with changing the salt concentration of the eluting buffer and attributed to a contraction of the DEAE-Sephadex A-50. Elution profiles (enzyme activity vs. fraction number) were examined with highly purified mitochondrial and cytoplasmic isoenzymes of human origin in bovine serum albumin and human serum. Recovery of the enzyme in the eluted fractions averaged 102% (SD, 2.0%) for specimens prepared from the purified isoenzymes and 104% (SD, 10.7%) for 38 human serum specimens. The separation technique showed linearity to catalytic concentrations in excess of 200 U/liter (reaction temperature 30 degrees C) for each isoenzyme. Additional information is presented regarding among-day precision and the effect of specimen dilution.
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PMID:Column-chromatographic separation of isoenzymes of aspartate aminotransferase. 2 23

Isolated rat livers were perfused at 35 degrees C with bovine serum albumin (40 g/l) in Krebs Ringer bicarbonate buffer, or with the same solution containing insulin (0.22 x 10(-6) mol/l), hydrocortisone (0.068 x 10(-3) mol/l), or both hormones together. Observations on the synthesis of bile and on perfusate levels of potassium, aspartate aminotransferase, urea and glucose showed that the presence of insulin and/or hydrocortisone had no beneficial effect on the perfused rat liver in vitro. There is little justification of the isolated liver.
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PMID:The effect of insulin and hydrocortisone on the isolated rat liver. 28 8

Eight different pools of purified human mitochondrial and cytoplasmic isoenzymes of aspartate aminotransferase were prepared, to examine the effects of the following matrix variables: the matrix support material (bovine serum albumin and polyvinylpyrrolidone), endogenous pyridoxal concentration, and azide as an antimicrobial preservation. Storage temperatures of 25 and 37 degrees C were used as a rapid and convenient means of accelerating the degradation process. Activity of the enzyme was measured with and without pyridoxal in the reaction solution. We found that the mitochondrial isoenzyme was consistently more labile than the cytoplasmic isoenzyme under identical storage conditions. Both isoenzymes were more stable in matrixes containing bovine serum albumin than in those containing polyvinylpyrrolidone. No apparent difference in the stability of either isoenzyme was observed at matrix pyridoxal concentrations of 15 micromol/L and 150 micromol/L. Only the mitochondrial isoenzyme in matrixes containing bovine serum albumin and 15 micromol of pyridoxal per liter had increased activity (about 9%) when pyridoxal was added to the enzymatic reagent. The amount of activity in reconstituted specimens did not apparently change after 72 h at 4 degrees C.
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PMID:Relative stabilities of purified human mitochondrial and cytoplasmic isoenzymes of aspartate aminotransferase in lyophilized materials. 43 29

Three groups of isolated rat livers were perfused at 35 C with Krebs-Ringer bicarbonate buffer containing commercial bovine serum albumin (BSA) which had been purified by gel filtration on a column of Sephacryl S-200 and used within 12 hr of purification, or BSA which had been purified by gel filtration and stored at -70 C until used. The ability of livers to produce bile, retain potassium, and to maintain a constant level of glucose in the perfusate was greatly improved in the presence of purified albumin which had not been frozen. Such livers also showed the highest rates of urea synthesis, but the rate of release of aspartate aminotransferase (GOT) from cells and the bile salt content of the bile produced were similar to those found with unpurified BSA. Livers perfused with purified albumin which had been stored in the frozen state were slightly inferior to those perfused with nonfrozen albumin in their ability to produce bile and urea, to retain potassium and GOT within cells, and to maintain a constant concentration of glucose in perfusates. The concentration of bile salts in the bile produced by this group was also lower than that found with the other two groups. Overall, isolated rat livers benefited from perfusion with purified albumin, although freeze storage of this material rendered it slightly inferior to the nonfrozen material in its ability to support the liver.
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PMID:Improved performance of the isolated rat liver when perfused with purified bovine serum albumin. 46 29

The effect of danazol in a dose of 600 mg a day was studied in 20 women with moderate or severe endometriosis. The clinical effect was found to be excellent and repeat laparoscopy after about 6 months treatment revealed a marked regression in all patients with only small residual foci of endometriosis in two of them. The side effects were few. The metabolic studies revealed a significant increase in serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT), serum potassium, serum albumin and serum creatinine, but a significant decrease in serum gamma glutamyl transpeptidase (GT). Serum sodium showed no alteration. A longitudinal study of basal plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and their responses to 25 microgram gonadotrophic releasing hormone (GnRH) i.v. as well as basal plasma levels of oestradiol, oestrone, progesterone and prolactin was performed. During treatment with danazol (600 mg a day) basal levels of LH, FSH, oestradiol, oestrone and progesterone were low but did not differ from the levels found in the early follicular phase of the menstrual cycle. On the other hand the pituitary response to GnRH was significantly greater for both LH and FSH than observed during the early follicular phase. These conflicting results are discussed. It seems that danazol inhibits the pituitary secretion of biologically active LH and FSH and this action is responsible for the decreased ovarian steroid secretion. Whether the atrophy of the uterine and ectopic endometrium is an effect of the reduced oestradiol levels or is a direct effect of danazol on endometrial oestrogen receptors, or a combination of both modes of action, is not clear.
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PMID:Hormonal, metabolic and clinical effects of danazol in the treatment of endometriosis. 53 48

Holotyrosine phenol-lyase (EC 4.1.99.2), a pyridoxal-5'-phosphate (PLP)- requiring enzyme, was shown to rapidly dissociate when injected into BDF1 mice. The holoenzyme dissociated when incubated in plasma but not 0.01 M potassium phosphate (pH 7.4) buffer at 37 degrees C. A nonspecific alkaline phosphatase from calf intestine was found to inactivate the holoenzyme at pH 7.4 and 37 degrees C. This inactivation was inhibited in the presence of 0.5 M potassium phosphate buffer. Two other PLP-requiring enzymes, aspartate aminotransferase (EC 2.6.1.1), and alanine aminotransferase (EC 2.6.1.2) were inactivated by alkaline phosphatase in a similar manner. Incubation of holotyrosine phenol-lyase in the presence of bovine serum albumin also resulted in a reduction of holoenzyme activity but partially protected the enzyme from inactivation by alkaline phosphatase. A nuclear fraction having PLP-hydrolyzing activity also inactivated holotyrosine phenol-lyase. A regulatory function for alkaline phosphatase in the metabolism of PLP-requiring enzymes is suggested by these data.
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PMID:Albumin and alkaline phosphatase as factors involved in the regulation of tyrosine phenol-lyase activity. 65 5

The Center for Disease Control (CDC), the New York State Department of Health (NYSDH), the College of American Pathologists, and 23 manufacturers of diagnostic products participated in an interlaboratory study of aspartate aminotransferase (EC 2.6.1.1) methodologies. Six different lyophilized materials were prepared and characterized and then distributed to 293 laboratories for aspartate aminotransferase measurements. The specimens included one human serum; four catalytic concentrations of the cytoplasmic isoenzyme, two purified from human erythrocytes, and two from porcine heart; and one matrix bovine serum albumin (30 g/liter) blank. The purified isoenzymes were prepared in the matrix. We present data on Michaelis parameters (Km and Vmax), Arrhenius plots, activation with pyridoxal 5-phosphate, vial-to-vial variability, and stability on reconstitution. The 281 responses showed that most of the laboratories used NADH-detection methods (91.1%), monitored at 340 nm (79.4%), and reported results in U/liter (89.4%). The percentage of laboratories reporting use of reaction temperatures of 30 and 37 degrees C was evenly divided, i.e., 42.7 and 42%, respectively. Analytical values reported by participating laboratories were categorized by reporting temperature, instrument, and method. Results were most consistent for a selected group of laboratories that supplemented optimized reaction solutions with pyridoxal 5-phosphate.
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PMID:An interlaboratory study of measurement of aspartate aminotransferase activity with use of purified enzyme materials. 65 80

Twelve substituted benzylidenes were evaluated for antiinflammatory activity against carrageenin-induced edema in rats. The protection afforded by these compounds at a dose of 100 mg/kg, i.p., ranged from 30 to 60%. Sodium salicylate (100 mg/kg, i.p.), used as a reference drug, exhibited a 30% antiinflammatory activity under similar experimental conditions. The in vitro effects of substituted benzylidenes were also investigated on the activity of trypsin during hydrolysis of bovine serum albumin, serum glutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase, and endogenous lipid peroxide formation by liver homogenates. These results have provided some correlation between antiinflammatory and antiproteolytic properties of substituted benzylidenes.
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PMID:Correlation between antiinflammatory and antiproteolytic properties of substituted benzylidenes. 84 Aug 88

Applications of centrifugal analysers to the field of clinical chemistry have been reviewed. Specific areas covered include recent developments in clinical enzymology with emphasis on aspartate aminotransferase and alkaline phosphatase. Also included are newer methods for uric acid, bilirubins and applications of enzyme linked immunoassays and immunochemical nephelometric techniques. Studies are described of the optimization of the BCG dye-binding procedure for serum albumin using an early absorbance reading.
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PMID:Progress and future of centrifugal analysers. 90 Jun 3

The rate of distribution of cell enzymes between the intravascular and extravascular space was studied, following a sudden decrease of enzyme activities in plasma. This rapid decrease of enzyme activities was achieved in rats by a rapid exchange of the blood with a twofold volume of a suspension of homologous erythrocytes in isoosmolar bovine serum albumin solution. After this plasmapheresis, the activities of seven cell enzymes in the plasma were decreased to 14 to 22% of their original values. The subsequent increase in activities showed different kinetics, depending on the enzyme. After 120 min, creatine kinase had reached the starting activity; malate dehydrogenase and aldolase reached their original activities after 180 min. Aspartate aminotransferase, glutamate dehydrogenase, alanine aminotransferase and pyruvate kinase increased more slowly and they had still not reached their starting values after 240 min. Repetition of the plasmapheresis after 90 min had no obvious effect on the kinetics of the subsequent activity increase. During the first minutes after plasmapheresis the adjustment of the activity equilibrium between the interstitial and the intravascular compartments depends mainly on the capillary permeability. It is therefore possible to determine half-life constants for the distribution of enzymes within the extracellular space. The constants for malate dehydrogenase and aldolase are almost identical with those determined by intravenous injection, whereas there are discrepancies in the constants for the remaining enzymes. The constants for pyruvate kinase and glutamate dehydrogenase are significantly lower, while those for aspartate aminotransferase, alanine aminotransferase and creatine kinase are significantly higher, than those determined after intravenous injection. Possible reasons for these differences are disucssed.
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PMID:[Plasmapheresis as an experimental model for studies on the extracellular distribution of enzymes. Distribution and transport of cell enzymes within the extracellular space. IV (author's transl)]. 93 47


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