PubMed Health⌕ Search

Biomedical subjects

V I Iakovleva

Publications and source records attributed to V I Iakovleva.

16 recordsLinked to original sources
PubMed1979

[Dependence of the rate of aspartate ammonia-lyase reaction catalyzed by free and immobilized cells of E. coli on temperature and preliminary thermal treatment].

The effects of temperature (45--55 degrees) and duration of thermal treatment on the L-aspartase activity of free and immobilized on polyacrylamide gel cells of E. coli, strain 85 were studied. It was found that preliminary thermal treatment of the cells at 50 degrees for 40--60 min is optimal for a high aspartase activity. Within the temperature interval of 20--55 degrees the temperature dependence of effective rate constants of L-aspartate synthesis obeys the Arrhenius equation, whereas the effective energy of activation is decreased from 12,6 to 3,6 kcal/mole, when the "activation" of the cells shows an increase.

Ammonia-Lyases↗
PubMed1979

[Kinetics of the aspartate-aminotransferase reaction catalyzed by free and immobilized cells of E. coli].

The kinetics of the aspartate-aminotransferase reaction were studied, using free and immobilized cells of E. coli, strain 85 as an enzyme source. It was shown that the reaction is limited by mass transport of the reagents through the bacterial cell membrane even at high concentrations of the substrates in the surrounding solution. The polyacrylamide gel-incorporated cells of E. coli, strain 85 catalyze the aspartate-aminotransferase reaction more effectively as compared to free or destroyed cells. In the latter case the reaction is characterized by the following kinetic parameters: the effective values of the stationary rate of the product accumulation and its stationary efflux from the cell are equal to (15,37 +/- 0.4) . 10(-6) mole/s/mg of protein and (3,01 +/- 0,8) . 10(-20) mole/s per 1 cell. respectively. The steady-state constant for glutamate synthesis from aspartic acid is equal to 0,22--0,23.

Aspartate Aminotransferases↗
PubMed1977

[Dynamics of lipid concentration changes in the livers of rats on biosatellites "Cosmos-605" and "Cosmos-782"].

Histological and histochemical investigation was carried out with rat liver specimens taken 9-11 h (from 6 rats), 24 (from 7 rats), 48 h (from 8 rats), and 25 (from 5 rats) and 27 days (from 7 rats) after the completion of 19.5- and 22.5-day of space bioflights in "Cosmos-605" and "Cosmos-782". The same number of specimens was investigated from corresponding models of the experiments carried out in the laboratory and from the control rats. The investigations demonstrated that in the rats sacrificed during the first two days, and in 25 and 27 days after the completion of the flight, no morphological changes developed in comparison with the control and with the animals from the laboratory experiments. Only some fluctuations in lipid content could be noticed in connection with the time of samples taking after the completion of the experiments. The greatest amount of lipids in the liver was observed in the rats sacrified 9-11 h after the completion of the flight, in 24 h the lipid level was still rather high, and in 48 h there was a tendency to their decrease. In 25 and 27 days the livers of the animals from the experimental group did not differ in their lipid content from those of the control animals. The changes in the lipid content observed in the liver during 8-48 h after the flight completion and during the period of afteraction indicate the reversibility of the adipose infiltration process, connected with lipid mobilization, dependent on stress-reaction.

Animals↗
PubMedDate not supplied

[Synthesis of L-aspartic acid by Escherichia coli and Pseudomonas fluorescens as related to the cultivation conditions].

The capacity of the cultures Escherichia coli str. 85, 113, BC, C and K-12 and Pseudomonas fluorescens str. 1 to synthesize L-aspartic acid from fumarate and ammonium ions was studied. E. coli str. 85 was shown to synthesize the largest amounts of aspartic acid. The cultivation conditions which helped to increase the activity several times were selected. The product of fumarate amination by ammonium ions was identified and found to be L-isomer of aspartic acid with an angle of rotation of [alpha] 20/D = +25,5 degrees in 6 N HCl.

Aspartic Acid↗
PubMedDate not supplied

[Aspartate aminotransferase activity of different strains of Escherichia coli].

Aspartate-aminotransferase activity was measured in strains of Escherichia coli grown no meat infusion broth. As an enzyme cells with damaged permeability of the cytoplasmatic membrane were used. The cells were damaged by an addition of toluene at a concentration of 1% of the reaction mixture by volume. These cells showed 50--60% aspartate-aminotransferase activity as compared with aliquotes of the cell-free extract. E. coli synthesized oxalacetic and glutamic acids from L-aspartic acid and alpha-ketoglutaric acid. Glutamic acid was identified by thin-layer chromatography on Fixion plates. E. coli str. 85 cells and their extracts grown on the synthetic medium containing glucose or glycerol showed a two-fold specific aspartate-aminotransferase activity as compared with those cultivated on meat-infusion broth.

Aspartate Aminotransferases↗
PubMedDate not supplied

[L-asparatic acid synthesis from ammonium fumarate by free and immobilized Escherichia coli cells].

E. coli 85 cells with a high aspartate-ammonia-lyase activity were immobilized through polyacrylamide gel incorporation. Proper conditions to assay aspartase activity of E. coli cells were developed. Kinetic patterns of aspartate-ammonia-lyase reaction catalyzed by free and immobilized E. coli 85 cells were studied. The synthesis of L-aspartic acid from ammonium fumarate had the following characteristics: specific activity of (4--6) . 10(-5) mmole/mg.sec for free cells and (6--8) . 10(-5) mmole/mg.sec for immobilized cells with their content in polyacrylamide gel of 5--10 mg protein per g wet gelm pH 8.3--10.0.

Aspartic Acid↗
PubMedDate not supplied

[Formation of neoplasms in dogs after chronic gamma irradiation at a low-intensity dose].

In order to estimate end effects of chronic prolonged gammairradiation of dogs, an exposure of 80 animals to irradiation was terminated and they were followed up closely. Out of 80 animals 30 dogs (1st series) were irradiated for 3 years and 50 dogs (II series) for 6 years. The dogs were exposed to irradiation at doses of 21 to 190 rad per year. Out of the total number of animals 22 dogs died. Post-mortem examinations showed neoformations in 13 animals (7 malignant and 12 benign neoformations). The highest number of tumors developed in dogs of the II series (10 out of 11) one-two years after irradiation (6 malignant tumors--malignant pheochromocytoma of adrenals; malignant adenoma of the hypophysis: polymorphocellular sarcoma of the liver; leucomyosarcoma of the uterus; bladder cancer; breast cancer; and 10 benign tumors--pancreatic adenoma; liver angioma; 2 papillary adenomas of the prostate; 3 renal adenomas; lipoma; polyps of the gall-bladder). Animals of the 1st series displayed 3 neoformations (1 malignant tumor--bladder tumor and 2 benign tumorsliver hepatoma and spleen angioma) 4--5 years after irradiation.

Animals↗
PubMedDate not supplied

[Histological and histochemical study of the liver of rats exposed on the Cosmos-690 biosatellite].

Liver samples of 12 rats flown aboard the biosatellite Cosmos-690 and irradiated with a dose of 800 rad and of 12 rats from the synchronous experiment were examined histologically and histochemically. On the 2nd and 27th postexperimental days the following morphological changes were detected; nuclear polymorphism of hepatocytes, a significant increase in the number of binuclear cells, and lipid accumulation in central lobes. The changes were more expressed on the 2nd day. These changes were induced by prolonged irradiation in space flight and synchronous experiment: they were not detected in the untreated animals.

Animals↗
PubMedDate not supplied

[Morphological effects in rats following a 22-day space flight].

A morphological examination of 27 rats flown onboard the biosatellite and sacrificed on the 1st-2nd and 26-27th postflight days demonstrated no significant changes in the structural organization of the vital organs and systems of the animal body. It was, however, found that the space exposure induced morphologically detectable changes in the musculo-skeletal system, hemo- and lymphopoiesis, hypothalamic-pituitary-adrenal system and the juxtaglomerular apparatus of the kidneys. The changes were reversible and nonspecific, and could be seen in animals exposed to ground-based hypokinetic and other stress experiments. Postflight the animals developed some reactions that were similar to those in humans. This helps to identify the morphological substrate of certain changes in the human body and to investigate their pathogenesis.

Animals↗