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Biomedical subjects

I A Kozlov

Publications and source records attributed to I A Kozlov.

At least 19 recordsLinked to original sources
PubMed1991

[The first clinical experience with orthotopic transplantation of the liver].

The article deals with material concerning the performance of 4 operations for orthotopic liver transplantation (OLT). The operations were carried out on 2 males and 2 females whose ages ranged from 20 to 52 years. The indications for OLT were as follows: ++hemangioendothelioma of the liver, hepatocellular carcinoma, cirrhosis-carcinoma of the liver, and metastatic affection of the liver. One male patient died immediately after the end of the operation, another patient died 3 days after the operation due to nonfunctioning of the transplant. In 2 female patients the operations were carried out successfully. One of them was discharged from the clinic in 62 days in a satisfactory conditions and a well functioning transplant. The other patient died from a complication which was not connected with the operation--perforation of the small intestine 69 days after OLT. The technical aspects of and the provision for the operation and the postoperative management of patients are discussed. The encountered complications are analysed.

Adult↗
PubMed1989

Glucose metabolism and insulin activity during cardiac surgery.

Disorders of glucose metabolism were investigated in 177 patients undergoing cardiac surgery. In group I patients, the cardiopulmonary bypass (CPB) priming fluid contained glucose. Patients in group II received neither glucose nor insulin during the operation. Group III received insulin-glucose therapy (IGT) during the operation (insulin, 1 U/kg/h, glucose, 0.5 g/kg/h). At the onset of CPB in group I, hyperglycemia was produced by the glucose load and by a relative reduction in insulin secretion. In group II, the start of the operation was accompanied by a rise in the titer of insulin antibodies. IGT resulted in normalization of the blood glucose level after CPB and stability of the insulin antibody titer during the investigation. The indices of myocardial contractility in group III were better than those of the "glucose-free" group II before and after CPB. In group II, indices of beta-cell function were moderately depressed 16 to 18 hours after the operation. Insulin and c-peptide level measurements demonstrated insulin production in group III on the first postoperative day. The results demonstrate that IGT has some potential benefit for glucose metabolism and myocardial function during cardiac surgery.

Adolescent↗
PubMed1985

The nucleotide binding site of F1-ATPase which carries out uni-site catalysis is one of the alternating active sites of the enzyme.

Nucleotide-depleted mitochondrial F1-ATPase binds 3'-(2')-O-(2-nitro-4-azidobenzoyl)-derivatives of ATP (NAB-ATP) and GTP (NAB-GTP) when these nucleotide analogues are added to the enzyme in equimolar quantities in the presence of Mg2+ (uni-site catalysis conditions). The binding of NAB-ATP is accompanied by its hydrolysis and inorganic phosphate dissociation from the enzyme; NAB-ADP remains bound to F1-ATPase. The F1-ATPase X NAB-ADP complex has no ATPase activity and its reactivation in the presence of an excess of ATP is accompanied by NAB-ADP release. The illumination of the F1-ATPase complexes with NAB-ADP or NAB-GDP leads to the covalent binding of one nucleotide analogue molecule to the enzyme and to the irreversible inactivation of F1-ATPase. It follows from the results obtained that the modification of just one of the F1-ATPase catalytic sites is sufficient to complete the inhibition of ATPase activity.

Adenosine Triphosphate↗
PubMed1985

The inhibition of mitochondrial F1-ATPase by 1,5-difluoro-2,4-dinitrobenzene.

1,5-Difluoro-2,4-dinitrobenzene completely inhibits F1-ATPase when it is used at micromolar concentrations and the inhibitor/enzyme molar ratio is equal to 3. The inhibition can be reversed by dithiothreitol treatment. 7-Chloro-4-nitrobenzofurazan treatment of F1-ATPase does not prevent the reaction of the enzyme with 1,5-difluoro-2,4-dinitrobenzene. The 1,5-difluoro-2,4-dinitrobenzene-induced inhibition is thought to be a result of the modification of a tyrosine residue with pK 9.1.

4-Chloro-7-nitrobenzofurazan↗
PubMed1985

The oxidation of sulfhydryl groups in mitochondrial F1-ATPase decreases the rate of its inactivation by the natural protein inhibitor.

The oxidants of the SH groups (o-iodozobenzoate, oxidized glutathione, etc.) and the divalent cations of some metals (Zn2+ and Cd2+) significantly slow down the rate of inactivation by the protein inhibitor of the isolated F1-ATPase and ATPase in submitochondrial particles. Modification of SH groups in the ATPase does not change the rate of inactivation but completely prevents the effect of oxidants.

Animals↗
PubMed1985

Tightly bound adenosine diphosphate, which inhibits the activity of mitochondrial F1-ATPase, is located at the catalytic site of the enzyme.

The binding of one ADP molecule at the catalytic site of the nucleotide depleted F1-ATPase results in a decrease in the initial rate of ATP hydrolysis. The addition of an equimolar amount of ATP to the nucleotide depleted F1-ATPase leads to the same effect, but, in this case, inhibition is time dependent. The half-time of this process is about 30 s, and the inhibition is correlated with Pi dissociation from the F1-ATPase catalytic site (uni-site catalysis). The F1-ATPase-ADP complex formed under uni-site catalysis conditions can be reactivated in two ways: (i) slow ATP-dependent ADP release from the catalytic site (tau 1/2 20 s) or (ii) binding of Pi in addition to MgADP and the formation of the triple F1-ATPase-MgADP-Pi complex. GTP and GDP are also capable of binding to the catalytic site, however, without changes in the kinetic properties of the F1-ATPase. It is proposed that ATP-dependent dissociation of the F1-ATPase-GDP complex occurs more rapidly, than that of the F1-ATPase-ADP complex.

Adenosine Diphosphate↗
PubMed1985

Tightly bound nucleotides affect phosphate binding to mitochondrial F1-ATPase.

The interaction of inorganic phosphate with native and nucleotide-depleted F1-ATPase was studied. F1-ATPase depleted of tightly bound nucleotides loses the ability to bind inorganic phosphate. The addition of ATP, ADP, GTP and GDP but not AMP, restores the phosphate binding. The nucleotides affecting the phosphate binding to F1-ATPase are located at the catalytic (exchangeable) site of the enzyme. The phosphate is thought to bind to the same catalytic site where the nucleotide is already bound. It is thought that ADP is the first substrate to bind to F1-ATPase in the ATP synthesis reaction.

Adenosine Diphosphate↗