Biomedical subjects

T N Popova

Publications and source records attributed to T N Popova.

31 records · Page 2Linked to original sources

PubMed1987

[The use of laparoscopy in the staging of stomach cancer].

Laparotomy is still being resorted to on a large scale to diagnose stomach cancer. This surgical intervention causes unjustified trauma and often exacerbates patient's condition. In a comparative study, postoperative complications were recorded in 13% of cases of laparotomy. The death rate was 2%. Patients were confined to hospital for an average of 15 days. Laparoscopy was performed in 105 patients for staging stomach cancer during clinical examinations. Metastases to abdominal cavity organs were detected in 61.9%. Laparoscopy did not involve complication or lethality. Patients stayed at the hospital not more than 5 days. A retrospective analysis of 193 cases of stomach cancer who had undergone diagnostic laparotomy showed that surgery could have been avoided in 42.5%, if laparoscopy had been used during clinical examination.

Adult↗

PubMed1986

[Determining the extent of gastric cancer by the thermographic method].

In an analysis of findings of thermographic examinations of the anterior abdominal wall in 167 patients with gastric cancer four types of thermograms were established: the 1st type of thermographic picture with focal hyperthermia in the epigastric area and left hypochondrium was characteristic of gastric tumors not exceeding the limits of the organ. Carcinomatosis of the abdomen is characterized by the 2nd type of the thermographic picture. The third and fourth types characterized by intensive infrared radiation along all the anterior abdominal wall indicate mostly inoperable tumoral process. Thus, thermography should be recommended for diagnosis of gastric cancer in combination with other methods of examination.

Abdominal Neoplasms↗

PubMedDate not supplied

[Characteristics of NADP-dependent isocitrate dehydrogenase functioning in pea leaves during salt stress].

In pea seedlings transferred to a medium containing 3% NaCl, NADP-dependent isocitrate dehydrogenase (NADP-IDH) activity in leaves increased more than twofold during the first hour, decreased, and increased again (approximately 1.5 times) by the 14th hour of exposure. Some catalytic and regulatory properties of NADP-IDH were studied using enzyme preparations purified from normal plants and plants exposed to salt stress. The results showed that Km for NADP-IDH in reactions with isocitrate and NADP decreased under stress by factors of 2 and 3, respectively. Specific features of enzyme activity regulation by citrate and trans-aconitate under these conditions were revealed. The inhibitory effects of gamma-aminobutyric acid (GABA) and 2-oxoglutarate on NADP-IDH from plants exposed to salt stress was stronger than that on the enzyme from normal plants. Glutamine and glutamate slightly activated the enzyme in both cases.

Aconitic Acid↗

PubMedDate not supplied

[Identification of catalytically active groups of lipoxygenase from wheat germ].

Catalytically active groups of lipoxygenase in wheat germs have been identified. Blocking of catalytically active groups by specific reagents, dependence of the enzyme activity on pH, enthalpy of ionization of pK1 and pK2, the enzyme photoinactivation allowed to make a conclusion that imidasole and hydroxyl groups take part in lipoxygenase catalytic cycle.

Binding Sites↗

PubMedDate not supplied

[Catalytic properties of cytoplasmic and mitochondrial aconitate hydratase from rat cardiomyocytes].

Enzymatic activity of aconitate hydratase (aconitase, EC 4.2.1.3) from the rat heart is localized in the cytoplasm (65%) and mitochondria (35%). Cytoplasmic and mitochondrial forms of aconitate hydratase were separated by ion-exchange chromatography on CM-Cellulose and CM-Sephadex. The two forms have similar molecular weight, optimal pH range, and spectral properties; however, they have different chromatography properties, Km for citrate and isocitrate, as well as sensitivity to Fe2+ ions.

Aconitate Hydratase↗

PubMedDate not supplied

[Effect of gamma-aminobutyric shunt metabolites on NAD-, NADP-isocitrate dehydrogenases, and aconitate hydratase activities in higher plants].

We studied the influence of metabolites of gamma-aminobutyric shunt of the tricarboxylic acid cycle on the activities of aconitate hydratase (EC.4.2.1.3) as well as NAD- and NADP-specific isocitrate dehydrogenases (EC.1.1.1.41 and EC.1.1.1.42, respectively) using purified enzyme preparations from pea leaves (Pisum sativum L.) and maize scutellum (Zea mays L.). gamma-Aminobutyric acid and succinate proved to have no significant effect on these enzymes, while 0.1-0.2 mM glutamate considerably activated NADP isocitrate dehydrogenase from the both sources, particularly, at unsaturating concentration of the substrate. Succinic semialdehyde stimulated the activities of aconitate hydratase and NADP isocitrate dehydrogenase. The obtained data points to a similar pattern of the effect of intermediates of gamma-aminobutyric shunt on the studied enzymatic activities for both photosynthetic tissues (pea leaves) and those with acidifying, transport, and digestive functions (maize scutellum). However, the absence of pronounced control effects of most metabolites on the studied enzymes allows us to assign them to a relatively inert pool of metabolites.

Aconitate Hydratase↗

PubMedDate not supplied

[Identification of catalytically active groups in inulinase from Bacillus polymyxa 722].

Inulinase from Bacillus polymyxa 722 hydrolyzing a polyfructosan inulin was studied. The dependence of inulinase activity on pH, measurements of pK value, calculation of ionization heat, photoinactivation with methylene blue, and inhibition with p-chloromercuribenzoate suggest that the active center of this enzyme contains imidazole and sulfhydryl groups. A possible mechanism underlying cleavage of beta-2,1-fructoside bonds in the inulin molecule with inulinase is considered.

Bacillus↗

PubMedDate not supplied

[Purification and characterization of lipases from wheat germ].

A method of isolation and purification of lipase (EC 3.1.1.3) from the germ of wheat (Triticum aestivum) is described. Electrophoretically homogeneous preparation of the enzyme (specific activity, 622.5 x x 10(-3) mumol/min per mg protein) was obtained after purification in 61 times. The molecular weight of the enzyme, determined by gel chromatography, was 143 +/- 2 kDa. The optimal conditions for the enzyme were 37 degrees and pH 8.0. Homogeneous preparation of the lipase exhibited high thermal stability: over 20% of original activity was retained after incubation of the preparation at high temperatures (60-90 degrees) for 1 h at pH 8.0.

Chromatography, Gel↗

PubMedDate not supplied

[Free-radical oxidation and regulation of cytoplasmic NADP-dependent malate dehydrogenase in rat cardiomyocytes at norm and under ischemia].

Experimental ishemia of rat myocardium was accompanied by increase of light sum (S) and maximal intensity (Imax) of chemiluminescence, amount of a malonic dialdehyde and conjugated dienes in cytoplasmic fraction. The activity of NADP-dependent malate dehydrogenase (EC 1.1.1.82; NADP-MDH) was 1.6 times higher in rat heart under ischemia. NADP-MDH was purified from normal and ischemia-exposed rat myocardium. Using NADP-MDH purified enzyme preparations the values of Hill coefficient for oxaloacetate (1.83 +/- 0.07 and 1.50 +/- 0.10) and Km for NADPH (0.058 +/- 0.003 and 0.096 +/- 0.004 mM) were determined for the enzyme at norm and under ischemia respectively. Effects of Fe2+, Ca2+, Cu2+ ions, H2O2, oxidized and reduced glutathione, adenine nucleotides influence on functioning of NADP-MDH from rat heart at norm and under ischemic conditions have been investigated.

Adenine Nucleotides↗

PubMedDate not supplied

[The intensity of free radical oxidation and catalytic properties of the rat liver NADP-isocitrate dehydrogenase in the norm and in toxic hepatitis].

Parameters of hepatic free radical oxidation and catalytic properties of NADP-isocitrate dehydrogenase (EC 1.1.1.42; NADP-IDH) have been investigated in normal rats and under conditions of toxic hepatitis. Development of hepatitis was accompanied by the increase of conjugated dienes, malondialdehyde and some chemiluminescence parameters. Toxic hepatitis was also accompanied by the increase of liver NADP-IDH. Homogenous preparations of liver NADP-IDH from normal and toxic rats exhibited different sensitivity to effectors studied (Fe2+, Ca2+, H2O2, reduced glutatione).

Animals↗

PubMedDate not supplied

[Regulatory properties of glucose-6-phosphate dehydrogenase from rat liver under conditions of the intensification of free-radical oxidation stimulated by toxic hepatitis].

Rat liver oxidative stress caused by toxic hepatitis is accompanied by increased activity of glucose-6-phospate dehydrogenase (EC 1.1.1.4.9; G6PDG). Electrophoretically homogenous G6PDG preparations purified from livers control rats and animals with hepatitis had specific activity of 4.13 and 6.54 EU, respectively. Fe2+ and Cu2+ ions showed non-competetive type inhibition of G6PDG at normal and under pathological condition, whereas Ca2+ activated G6PDG. Hydrogen peroxide exhibited mixed type inhibition of G6PD (K(i) 0.36 mM and 0.95 mM at norm and experimental toxic hepatitis, respectively). The participation of oxidised and reduced glutathione in G6PDG activity regulation has been shown.

Animals↗

PubMedDate not supplied

[Subcellular localization, purification, and various catalitic properties of aspartate aminotransferase from Spirodela polyrhiza].

Intracellular distribution of aspartate aminotransferase (AAT) in Spirodela polyrhiza (Lemnaceae), strain SJ, has been studied by differential centrifugation. The bulk of the enzyme (73% of total cellular content) was localized in the cytoplasm and 24% activity was localized in chloroplasts. Purified cytoplasmic and chloroplastic isozymes differed by their affinity for substrates. The reaction balance was shifted towards direct and reverse transamination in the cytoplasm and chloroplast, respectively. Competitive inhibition of AAT by excessive substrates and enzyme affinity modulation by certain intermediates of the tricarboxylic acid cycle (isocitrate, succinate, and citrate) were observed. Possible involvement of AAT isozymes in the coordination of carbon and nitrogen metabolism through the regulation of 2-oxoglutarate synthesis and utilization in different cellular compartments is discussed.

Araceae↗

PubMedDate not supplied

[Catalytic properties of 6-phosphogluconate dehydrogenase from rat liver in normal state and during toxic hepatitis].

Experimental toxic hepatitis is accompanied by a decrease of 6-phosphogluconate dehydrogenase (6PGD, 1.1.1.44) activity in rat liver. Enzyme preparations of 6PGD, obtained from livers of control group rats and animals with toxic exhibit the same molecular mass of 114.2 +/- 5.8 kDa. However G6PD isolated from liver of animals with toxic hepatitis exhibited altered Km and pH-optimum values. Reduced glutathione inhibited 6PGD-activity from the liver of control group rats and did not affect the enzyme from liver of animals with toxic hepatitis. Inhibition effect of oxidized glutathione is stronger in the pathological state. Malate, citrate, 2-oxoglutarate and isocitrate activated the enzyme from control animals, but did not the enzyme isolated from animals with hepatitis. Regulation of 6PGD-activity from liver of control and experimental animals by some nucleotides (NAD, ADP, AMP) and ribose-5-phosphate was also different.

Animals↗