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Biomedical subjects

A Dubin

Publications and source records attributed to A Dubin.

At least 91 records · Page 5Linked to original sources
PubMed1981

The interaction between chymotrypsin and horse leucocyte neutral proteinases inhibitor.

The inhibition of alpha-chymotrypsin by horse leucocyte neutral proteinases inhibitor was time-dependent with synthetic substrate N-benzoyl-L-tyrosine ethyl ester but not with azo-casein. This time dependence could be used to calculate the rate constant kass for the association of the inhibitor with bovine alpha-chymotrypsin (kass = 0.3 X 10(6)M-1 S-1). The inhibitor reacted with chymotrypsin at a molar a ratio of 1 : 1. The dissociation constant Ki = 0.30 X 10(9)M of the complex indicates a very strong interaction between enzyme and inhibitor.

Animals↗
PubMed1980

Regulation of vitamin K-dependent carboxylation.

Vitamin K-dependent carboxylation activity measured with pentapeptide substrate (Phe-Leu-Glu-Glu-Leu) gradually decreases upon in vivo injection of vitamin K to vitamin K-deficient rats. A decrease in pentapeptide carboxylation can also be observed by the in vitro addition of antibodies against prothrombin and other vitamin K-dependent proteins to the soluble system derived from vitamin K-deficient rat liver microsomes. In both cases, adding back in vitro partially decarboxylated vitamin K-dependent proteins or purified hepatic prothrombin precursor restores the level of pentapeptide carboxylation. After warfarin treatment, a 3-fold increase in carboxylation results, which can be abolished by giving cycloheximide along with the warfarin. However, the resulting decreased activity is restored by the in vitro addition of partially decarboxylated vitamin K-dependent proteins. These data are consistent with the hypothesis that (after warfarin treatment) increased peptide carboxylation is primarily due to activation of the system by precursor proteins, rather than synthesis of an increased amount of enzyme.

Animals↗
PubMed1979

Th activities of perfused livers of control and streptozotocin diabetic rats in the synthesis of some plasma proteins and peptides.

By measuring the incorporation of 14C-DL-leucine a decreased capacity of isolated perfused steptozotocin diabetic rat liver to synthetize plasma total proteins, albumin and the seromucoid fraction was found as compared with a control. The relative rate of synthesis of the seromucoid proteins calculated as proportional to the rate of synthesis of albumin or the total plasma proteins was approximately twice as great as in control liver. 14C-DL-leucine was also incorporated in perfused liver into the nonprotein but non-dialysable sugar-peptide fraction but the synthesis of the glycopeptide components of this fraction was markedly reduced in diabetic rat liver.

Animals↗
PubMed1978

The effect of D-galactosamine on plasma protein synthesis by the perfused rat liver from turpentine-stimulated donors.

D-galactosamine (100 mg) was added to the reconstituted blood during 4h perfusion of livers isolated either from control rats or those injected with turpentine 20 h or 5 h earlier. This dose of galactosamine administered 30 min before [3H]lysine significantly inhibited the incorporation of the label into liver proteins, and even more into plasma proteins, but albumin and acute-phase reactants (fibrinogen, seromucoid fraction, Concanavalin A-adsorbed glycoproteins) were all similarly affected. When galactosamine was administered in vivo simultaneously with turpentine, and the liver was isolated 5 h later, trauma-induced fibrinogen synthesis was selectively inhibited. This can be explained either by a differential control of synthesis of various acute-phase reactants, or by augmentation of catabolism of fibrinogen in galactosamine-treated rats. Crossed immunoelectrophoresis of the full perfusate or Concanavalin A-adsorbed glycoproteins did not reveal any significant effect of galactosamine on the protein pattern obtained from control or turpentine-stimulated liver donors.

Animals↗
PubMed1978

The carcinoembryonic antigen test in urologic cancer.

The diagnostic value of the CEA test was evaluated in 2,029 blood and urine samples from 308 patients with urologic cancer, 13 with nonurologic cancer, 20 urologic patients with nonmalignant disease, and in 30 controls. The blood CEA test was positive in 50% of the patients with active urologic cancer and in 35% of those with inactive cancer. The urine CEA test was elevated only in patients with active bladder cancer, but most of these had concurrently infected urines. At the present time, the CEA test does not reflect the accuracy necessary for an acceptable diagnostic test for the detection of urologic cancer.

Carcinoembryonic Antigen↗
PubMed1977

A polyvalent proteinase inhibitor from horse-blood-leucocyte cytosol. Isolation, purification and some molecular parameters.

Cytosol of horse blood polymorphonuclear leucocytes contains an inhibitor active against neutral proteinases from the granules of these cells and against chymotrypsin, elastases I and II from pig pancreas, but not against trypsin. A method has been elaborated to isolate and purify this inhibitor by means of salting out with ammonium sulphate (45---70% saturation), followed by chromatography and rechromatography on a column of DEAE-Sephadex A-50. The preparation obtained is homogeneous during polyacrylamide gel electrophoresis in the presence of 0.1% sodium dodecylsulphate after reduction with 2-mercaptoethanol. It is a thermolabile protein soluble at its isoelectric point (pH 5.38) and having a molecular weight of 35200 but aggregating in solutions of low ionic strength and irreversibly precipitating during dialysis at pH 4.0. The results obtained show the similarity of this inhibitor isolated from horse blood leucocyte cytosol to other inhibitors isolated from human or pig blood leucocytes.

Animals↗
PubMed1976

Isolation and some molecular parameters of elastase-like normal proteinases from horse blood leucocytes.

Cytoplasmic granules were isolated from horse blood polymorphonuclear leucocytes by the heparin method and extracted with 0.9% NaCl by repeated freezing. Soluble proteins were separated on a column of Sephadex G-75 followed by chromatography on a column of CM-Sephadex with a NaCl gradient. Gel filtration, density-gradient centrifugation, isoelectric focusing and 0.1% sodium dodecyl sulphate/polyacrylamide-gel electrophoresis at pH 7.0 and at pH 4.5 were used to determine molecular parameters of proteinases. Three enzymes hydrolysing both casein and N-benzyloxycarbonyl-L-alanine nitrophenyl ester were found in the granule extract: proteinase 1, mol.wt. 38000, pI5.3; proteinase 2A, mol.wt. 24500, pI8.8; and proteinase 2B, mol.wt. 20500, pI above 10. The latter two elastase-like proteinases were purified to apparent homogeneity.

Animals↗
PubMed1976

Substrate specificity and modifications of the active centre of elastase-like neutral proteinases from horse blood leucocytes.

Two proteinases (2A and 2B) purified from the granular fraction of horse blood leucocytes degrade casein (Km values 12.8 and 6mg/ml respectively) with maximum activity at pH 7.4 and in the presence of 2m-urea. Urea-denatured haemoglobin, fibrinogen, albumin and resorcin/fuchsin-stained elastin are digested at a slower rate. The enzymes hydrolyse synthetic substrates of elastase, N-benzyloxycarbonyl-L-alanine 4-nitrophenyl ester (Km 0.114 and 0.178 mM) and N-acetyl-tri-L-alanine methyl ester (Km 5.55 and 0.98 mM), but they do not hydrolyse synthetic substrates of trypsin, chymotrypsin and thrombin. The examined proteinases are completely inhibited by 2 mM-di-isopropyl phosphorfluoridate and show a sensitivity to butyl and octyl isocyanates similar to that of pancreatic elastase. The pH-dependence of their photoinactivation in the presence of Rose Bengal indicates the presence of histidine in the active centre. Proteinase 2A rather insensitive to iodination by IC1 as is pancreatic elastase, whereas proteinase 2B is totally inactivated after incorporation of five iodine atoms per enzyme molecule.

Animals↗
PubMed1976

Inhibition of the liver and plasma protein acute-phase response in mice by D-galactosamine.

Local inflammation evoked in Swiss albino mice by subcutaneous injection of Celite resulted in a rise of liver tyrosine aminotransferase activity and plasma level of fibrinogen and seromucoid, while liver alanine aminotransferase activity and plasma level of fibrinogen and seromucoid, while liver alanine aminotransferase activity and the plasma level of albumin and total protein remained unaltered. By measuring the incorporation of [14C] leucine, stimulation of liver and plasms protein synthesis by Celite injection was demonstrated. Administration of D-galactosamine (2-5 mg/10 g body weight) inhibited the enhanced synthesis of liver proteins, and especially of trauma-induced synthesis of plasma fibrinogen and seromucoid. The inhibitory effect of galactosamine was most pronounced when the amino sugar was injected simultaneously with Celite and then protein synthesis was measured 6 h later. The results obtained support the idea that high doses of galactosamine inhibit transcription of trauma-inducible mRNA in the liver and thus block the acute-phase response.

Animals↗
PubMed1976

Comparison of protein components of the plasma membrane fraction from rat liver and Morris hepatomas 5123D and 7777.

Isolated plasma membrane fractions from rat liver and Morris hepatoma 5123D and 7777 were labelled with radioiodine 125I by a chemical or enzymatic procedure and then were solubilized in 2 per cent solution of sodium dodecyl sulphate containing 1 per cent 2-mercaptoethanol. Solubilized proteins were separated into 20--22 zones staining with Coomassie Brilliant Blue R-250 after disc gel electrophoresis (7.5 per cent polyacrylamide gel). The high similarity of electrophoretic patterns of polypeptide components of all three preparations of cellular membranes was found in distinction to apparent differnces in the amount and disposition of substances stained with Schiff's reagent. Some tentative conclusions were drawn on the disposition of proteins within membrane structure studied by the method of labelling by chemical and enzymatic procedures (distinguishing between extrinsic and integral proteins).

Animals↗
PubMed1975

Carcinoembryonic antigen test in renal cell carcinoma.

CEA (carcinoembryonic antigen) determinations were performed on 203 blood and urine samples from 23 patients with renal cell carcinoma. Neither the blood nor the urine CEA test was able to confirm the diagnosis or predict the status of the disease in more than one half of these patients. As presently constituted, the CEA test is not accurate for the diagnosis or prognosis of renal cell carcinoma.

Adenocarcinoma↗
PubMed1975

The CEA test in urologic cancer: an evaluation and a review.

The diagnostic value of the carcinoembryonic antigen test was evaluated in 2,029 blood and urine samples from 308 urologic cancer patients, 13 patients with nonurologic cancer, 20 urologic patients with nonmalignant disease, and in 30 controls. The blood CEA test was positive in 50% of patients with active urologic malignancy and in 35% of patients with inactive malignancy. The urine CEA test was elevated only in patients with active bladder cancer but most of these patients had concurrently infected urines. At the present time, the CEA test does not reflect the accuracy necessary for an acceptable diagnostic test for the detection of urologic cancer.

Carcinoembryonic Antigen↗