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Biomedical subjects

M V Demcheva

Publications and source records attributed to M V Demcheva.

7 recordsLinked to original sources
PubMed1999

Endoscopic injection of bleeding esophageal varices with a poly-N-acetyl glucosamine gel formulation in the canine portal hypertension model.

BACKGROUND: It has been shown that poly-N-acetyl glucosamine produces rapid hemostasis by stimulating erythrocyte aggregation. Endoscopic injection of this substance may be effective in the treatment of bleeding varices. METHODS: In eight heparinized dogs with a bleeding esophageal varix greater than 2 mm in diameter, 2.5% to 3.5% poly-N-acetyl glucosamine gel was injected intravariceally and paravariceally. Endoscopy, endosonography, and histopathology were performed at 1, 7, 21, and 90 days after injection. RESULTS: In all cases, the variceal hemorrhage was stopped with three to four injections of a mean total gel volume of 1.9 mL. No recurrence of bleeding, ulceration, or stricture formation occurred. Through replacement of the gel by connective tissue, the varix was permanently obliterated in its whole course in five cases and in more than 70% of its length in three cases. No embolization and no poly-N-acetyl glucosamine antibodies were detected. CONCLUSIONS: Endoscopic injection of bleeding esophageal varices in this animal model with the use of poly-N-acetyl glucosamine gel was an effective and safe method for stopping the hemorrhage and inducing permanent varix obliteration.

Acetylglucosamine↗
PubMed1994

Monoclonal antibodies against metalloporphyrins. Specificity of interaction with structurally different metalloporphyrins.

Monoclonal antibodies against Pd-coproporphyrin I have been obtained. The antibody specificity for free as well as for conjugated Pd-coproporphyrin I is characterized. Affinity constants are estimated for 3 monoclonal antibodies effectively interacting with free Pd-coproporphyrin I. A comparative study on the binding of monoclonal antibodies with analogues and derivatives of Pd-coproporphyrin I has revealed that the antigen is mainly located inside the antibody paratope. The protein adjoins complementary to the metalloporphyrin in such a manner that antibodies obtained discern only isomer I, and to some degree, isomer III of coproporphyrin.

Animals↗
PubMed1994

Universal phosphorescence immunoassay.

The aim of this study is to develop a universal phosphorescence immunoassay method using monoclonal antibodies to Pd-coproporphyrin (Pd-CP) and conjugates of various proteins with Pd-CP. Pd-CP and monoclonal antibodies obtained allow a convenient method for the determination of various antigens to be developed. The conditions for immunological reactions with Pd-CP were optimized with respect to the components affecting the nonspecific binding Pd-CP and Pd-CP conjugates.

Animals↗
PubMed1994

[Co-oxidation of phenols and 4-aminoantipyrene catalyzed by microperoxidase and their complexes with proteins].

The kinetic parameters of 4-aminoantipyrine (AAP) co-oxidation with phenol or p-iodophenol in a wide range of hydrogen peroxide concentrations were compared for microperoxidases MP-8, MP-9, MP-11, horseradish peroxidase (HRP) and peroxidase of Arthromyces ramosus (PAR). The peroxidatic activity increased in the following order: HRP > PAR > MP-9 > MP-8 > MP-11. Microperoxidase complexes with human serum albumin (1:1) retained their peroxidatic activity at high H2O2 concentrations, protecting haem from destruction by active radicals. Monoclonal antibodies against porphyrin decreased the peroxidatic activities of three microperoxidases during co-oxidation of AAP and phenol and protected haem. Inert proteins (BSA, ovalbumin) had little effect on the HRP activity, whereas enzyme-specific antibodies strongly activated HRP at high concentrations of hydrogen peroxide, thereby forming an immune complex protecting HRP from its dissociation down to haem and the apoenzyme.

Amino Acid Sequence↗
PubMed1987

[Formation of a pentose phosphate cycle metabolite, erythrose-4-phosphate, from initial compounds of glycolysis by transketolase from the rat liver].

Using ion-exchange chromatography of sucrose phosphates on Dowex-1, it was demonstrated that the highly purified rat liver transketolase (specific activity 1.7 mumol/min.mg protein) is capable of catalyzing the synthesis of erythrose-4-phosphate, a metabolite of the pentose phosphate pathway non-oxidizing step, from the initial participants of glycolysis, i. e., glucose-6-phosphate and fructose-6-phosphate. As can be evidenced from the reaction course, the second product of this synthesis is octulose-8-phosphate. The reaction was assayed by accumulation of erythrose-4-phosphate. The soluble fraction from rat liver catalyzes under identical conditions the synthesis of heptulose-7-phosphate (but not erythrose-4-phosphate), which points to the utilization of the erythrose-4-phosphate formed in the course of the transketolase reaction by transaldolase which is also present in the soluble fraction. The role of the transketolase reaction reversal from the synthesis of pentose phosphate derivatives to glycolytic products is discussed. The transketolase reaction provides for the relationship between glycolysis and the anaerobic step of the pentose phosphate pathway which share common metabolites, i. e. glucose-6-phosphate and fructose-6-phosphate.

Animals↗
PubMedDate not supplied

Kinetics of oxidation of o-dianisidine by hydrogen peroxide in the presence of antibody complexes of iron(III) coproporphyrin.

The complex of iron(III) coproporphyrinI (FeCPI) with antibody D5E3 was studied as an artificial peroxidase, using o-dianisidine as a substrate. At saturation with respect to antibody, the initial rates of o-dianisidine oxidation are practically the same for free and bound FeCPI at a concentration 5 x 10(-9)M, but the catalytic rate constant (kc) for bound FeCPI exceed (kc) for free FeCPI by two- to three-fold. This difference can be explained by a real enhancement of (kc) at the antibody-active site. The dependence of initial rates of the reaction on substrate concentrations obeyed Michaelis-Menten kinetics and revealed substrate activation at high concentrations of o-dianisidine. A comparison of the Stern-Volmer constants for o-dianisidine-induced quenching of the porphyrin fluorescence proves that antibody-bound coproporphyrin is equivalently accessible to the substrate as protoporphyrin bound to apoperoxidase from horseradish peroxidase (HRP). Based on analysis of the (kc) dependence on H2O2 concentrations in the FeCPI-antibody system, we suggest that interaction with hydrogen peroxide is the rate-limiting step for the oxidation reaction.

Antibodies, Catalytic↗