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Biomedical subjects

A Dubin

Publications and source records attributed to A Dubin.

At least 73 records · Page 4Linked to original sources
PubMed1986

Proteinase inhibitors from horse plasma and leucocytes: properties and biological functions.

Alpha-1-antiproteinase (alpha 1-PI) and alpha-2-macroglobulin (alpha 2-M) from horse plasma and the proteinase inhibitor from horse leucocyte cytosol were purified and some of their physicochemical parameters estimated. Effective molar ratio, inactivation rate constants kon and apparent inhibitory constants Ki were determined for the reaction of these inhibitors and several leucocyte and pancreatic serine proteinases. It appears that alpha 1-PI, similarly to human inhibitor, controls the activity of leucocyte elastases in plasma and the lung. On the other hand, the physiological role of the leucocyte cytosol inhibitor is to protect the cytoplasm against the destructive activity of leucocyte proteinases rather than to protect the surrounding tissues.

Animals↗
PubMed1986

The interaction between some serine proteinases and horse leucocyte inhibitor.

Horse blood leucocyte cytosol exhibits a broad inhibitory activity against serine proteinases. The purified inhibitor was exposed to investigated enzymes (trypsin, chymotrypsin, elastases and serine proteinase from S. aureus) for variable time and the products were analyzed by gradient polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. The molar ratio I:E, association rate constants k on and inhibition constants Ki for the enzymes and inhibitor were determined. The examined elastases form stable, stoichiometric complexes with the inhibitor (Ki less than 10(-10) M), and do not undergo proteolytic degradation during 30 min incubation at 20 degrees C even at the 2-fold molar excess of the proteinases. The reactions with elastases are extremely rapid (k on greater than 10(7) M-1 s-1) and are completed within one second whereas similar reactions with chymotrypsin and trypsin are much slower (k on = 3 X 10(5) M-1 s-5 and 5 X 10(2) M-1 s-1, respectively). Serine proteinase from S. aureus neither react nor inactivates the investigated inhibitor. The complexes of the inhibitor with trypsin and chymotrypsin are digested even at a molar ratio I:E = 2:1. All these observations point out that the inhibitor from horse leucocyte cytosol is a specific and effective inhibitor of elastases.

Animals↗
PubMed1986

Elastinolytic activity of horse leukocyte proteinases. Comparison with elastases from human leukocytes and porcine pancreas.

Three proteinases from the azurophilic granules of horse leucocytes are typical elastases degrading elastin at neutral pH. Both proteinases: 1 and 2A exhibit similar elastinolytic activity, comparable with human leucocyte elastase (HLE). In relation to human enzyme, elastase 2B shows several-fold higher activity, which is comparable to the porcine pancreatic elastase activity (PPE). Similarly to HLE elastinolytic activity of the horse proteinases increases at higher ionic strength: twofold in case of 1 or 2A and fivefold for 2B. Significant activity observed during degradation of homologous lung elastin, implies the possible role of these enzymes during pathological injury of connective tissue in the lower respiratory tract and suggests similar pathogenesis of horse and human pulmonary emphysema.

Animals↗
PubMed1985

Plasma proteinase inhibitors in Morris hepatoma-bearing rats: changes in the blood level and synthesis in tissue slices.

The antiproteinase activities against trypsin, chymotrypsin, elastase, papain and rat leucocyte proteinases were determined in plasma from control and Morris hepatoma-bearing rats. Bovine trypsin and chymotrypsin were similarly inhibited by the two types of plasma whereas porcine pancreatic elastase, papain and rat leucocyte neutral proteinases were more efficiently inhibited by plasma from tumour-bearing rats. The increased plasma concentrations of some proteinase inhibitors, as determined by rocket immunoelectrophoresis, are suggested to be responsible for the observed differences in inhibition. The highest increases in plasma of tumour-bearing rats were observed for alpha 2-macroglobulin and alpha 1-acute-phase globulin. The synthesis and secretion of six proteinase inhibitors: antithrombin III, alpha 1-proteinase inhibitor, alpha 1-macroglobulin, alpha 2-macroglobulin, alpha 1-acute-phase globulin and haptoglobin, as well as albumin, were measured in tissue slices from rat liver and Morris hepatoma after incubation with [14C]leucine. Local inflammation inflicted upon the tumour-bearing rats increased formation of acute-phase proteins in liver slices but not in hepatoma slices.

Animals↗
PubMed1985

Identification and characterization of prostaglandin-binding components in rat ileum.

A specific prostaglandin E2 (PGE2) binding component was identified in the membrane fractions of rat ileum. Two ligands, 3H-PGE2 and 14C-PGE2, competed for the binding sites in crude homogenates of ileum during competition experiments, demonstrating the presence of a limited number of binding sites. There was enhancement in the specific 3H-PGE2 binding to particulate fractions over control when endogenous prostaglandin synthesis was blocked by the administration of indomethacin to rats prior to sacrifice. The specific prostaglandin-binding protein was purified by a combination of [NH4]2SO4 fractionation and Sephacryl S-200 column chromatographic techniques, and shown to be active after these biochemical steps.

Animals↗
PubMed1985

Inhibition of horse leucocyte proteinases by eglin, a proteinase inhibitor from leeches.

Interaction of eglin c with three neutral proteinases (1, 2A and 2B) from horse leucocytes was investigated using synthetic and protein substrates. With N-tert-butyloxycarbonyl-L-alanine-p-nitrophenyl ester as substrate inhibition of proteinase 1 and 2A was practically complete at equimolar inhibitor concentrations (Ki below 1 nMol/l). The complex with proteinase 2B showed a dissociation constant of approximately 25 nMol/l. The latter proteinase was only partly inhibited also in the presence of azocasein, whereas almost linear inhibition was observed for all 3 proteinases with fibrinogen as substrate. The inhibition rate constants (kon) for horse leucocyte proteinases with eglin were in the range of 8 to 13 X 10(5) M-1 S-1.

Animals↗
PubMed1985

Fluorescent substances in uremic and normal serum.

We measured the fluorescence, at various excitation (Ex) and emission (Em) wavelengths, of serum ultrafiltrates and fractions of serum resolved by chromatography on Sephadex G15, studying both normal subjects and patients in chronic renal failure requiring hemodialysis. We found hitherto undescribed fluorescence at Ex 380 nm/Em 440 nm and Ex 400 nm/Em 460 nm, the intensity being greatly increased in patients with chronic renal failure in comparison with normal subjects (p less than 0.005). This fluorescence persisted unaltered when serum was filtered through membranes having cutoffs ranging from 10 000 to 500 Da. Each serum fraction resolved by gel chromatography demonstrated a characteristic fluorescence, which was generally much more intense in uremics. The most intense fluorescence (Ex 380 nm/Em 440 nm and Ex 400 nm/Em 460 nm) was emitted in the higher-Mr fractions.

Blood Chemical Analysis↗
PubMed1984

Significance of serum aminograms in diagnosis and prognosis of liver diseases.

The diagnosis, prognosis, and treatment of various liver diseases are still frequently equivocal despite the various liver function tests and invasive procedures presently available to the clinician. The introduction of the Beckman Amino Acid Analyzer Model 119 Cl, greatly facilitated the determination of the individual amino acids in serum and cerebrospinal fluid, and the data thus obtained seem to help in the differentiation of some of the commoner types of liver disease. These data indicate that changes in the concentration of some of the aromatic amino acids (AAA) and branched chain amino acids (BCAA) are helpful in the diagnosis, evaluation of the severity of the hepatic morphologic changes, and prognosis of the type of liver disease. Moreover, the ratio between the AAA and the BCAA seems to be indicative of certain liver diseases. We describe the alterations in the amino acid patterns which may help in the diagnosis, prognosis, and treatment of patients with certain types of liver disease.

Amino Acids↗
PubMed1984

Alpha 2-macroglobulin from horse plasma. Purification, properties and interaction with certain serine proteinases.

alpha 2-macroglobulin was isolated by polyethylene glycol precipitation, gel filtration on Sephacryl S-300 and DE-52 cellulose chromatography, with 20% yield. The preparation obtained was homogenous as tested by biochemical and immunological criteria. Its molecular mass was estimated at 800,000, comprising of four identical subunits. The isoelectric point of our preparation was 4.8 and two molecules of serine proteinases per 1 molecule of inhibitor were bound.

Animals↗
PubMed1984

Separation, isolation and amino acid composition of uremic peptides.

Gel filtration and thin layer chromatography were conducted on sera from uremic patients and normal subjects for the isolation of nitrogenous substances unique to uremia. Many ninhydrin-positive substances were found in greater amounts in uremic patients compared to normal subjects. Some of these ninhydrin-positive substances were also detected by staining with chlorine-tolidine. Amino acid analysis of these substances showed considerable qualitative and quantitative differences, perhaps reflecting interference with enzymatic activity by the uremic environment.

Amino Acids↗
PubMed1983

Synthesis and secretion of some plasma proteins by tissue slices of Morris hepatoma 7777 and liver from control and turpentine-injected rats.

Slices of Morris hepatoma 7777 or rat liver isolated from control or turpentine-injected rats were incubated for 2 h with 14C-leucine. Radioactivities incorporated into albumin, alpha-fetoprotein, fibrinogen, alpha 1-AP-globulin, haptoglobin and alpha 1-acid glycoprotein were determined after the proteins had been isolated from the incubation medium or tissue homogenate by immunoprecipitation with monospecific antisera. It was found that hepatoma synthesizes fibrinogen, alpha 1-AP-globulin and alpha 1-acid glycoprotein in the amounts comparable to rat liver, whereas formation of albumin and haptoglobin is reduced 5- to 10-fold. Local inflammation elicited by injection of turpentine to tissue donors increased formation of acute-phase protein in liver slices but had no effect on synthesis of these proteins in preparations of Morris hepatoma, although certain ultrastructural changes in the Golgi complex were observed not only in the liver but also in the tumour.

Animals↗
PubMed1983

Kinetics and stoichiometry of inactivation of some pancreatic and leucocyte serine proteinases by rabbit alpha 1-proteinase inhibitors F and S.

Purified rabbit alpha 1-proteinase inhibitors F and S were incubated with bovine trypsin, chymotrypsin or horse leucocyte neutral proteinases in order to determine the stoichiometry of inhibition, inactivation rates of the enzymes and dissociation constants of the complexes. Trypsin reacted with the two forms of alpha 1-PI with different velocities but in the molar ratio of 1:1 and yielding stable complexes. Chymotrypsin reacted very fast with the two forms of alpha 1-PI but required a three-fold molar excess of alpha 1-PI-S for almost complete inhibition, and again the dissociation constants were low. Leucocyte proteinases also needed certain molar excess of the inhibitor but the reaction was complicated by instability of the complexes, especially with Z-Ala-ONp as substrate. We conclude that the interaction of rabbit alpha 1-PI with leucocyte proteinases, and particularly alpha 1-PI-S with chymotrypsin, includes not only complex formation but also some inactivation of the inhibitor.

Animals↗
PubMed1982

Changes in the blood level and affinity to concanavalin A of rat plasma glycoproteins during acute inflammation and hepatoma growth.

Plasma concentrations of ten individual proteins were measured by electroimmunoassay in young male Buffalo rats following injection of turpentine oil or implantation of Morris hepatoma 7777. The highest relative responses to inflammation and tumour growth were found for alpha 2-macroglobulin, alpha 1-acute-phase globulin and alpha 1-acid glycoprotein. As shown by crossed immuno-affinoelectrophoresis the concanavalin A-reactive fractions of the latter two glycoproteins were predominantly increased in plasma from injured and tumour-bearing rats.

Animals↗