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Biomedical subjects

S P Siatkin

Publications and source records attributed to S P Siatkin.

At least 19 recordsLinked to original sources
PubMed2006

[Polyamines and mental diseases].

The authors make an attempt to understand and evaluate the role of polyamines in the development of endogenous mental diseases. The article is dedicated to distribution and exchange of polyamines in the central nervous system, their metabolic and regulatory associations with gamma-aminobutyric acid and dopaminergic systems, as well as to possible neuromediatory and neuromodulatory functions of polyamines. The paper is also concerned with effects of psychotropic agents on polyamine metabolism and contains a hypothesis on the role of polyamines in etiopathogenesis of schizophrenia.

Central Nervous System↗
PubMed2002

[Morphological and biochemical features of cerebral beta-amyloidosis in long-livers].

This is the first assessment of the pathogenetic values of some environmental factors in the occurrence and progression of cerebral beta-amyloidosis (Alzheimer's disease, senile dementia) in long-livers of different climatic areas of the Republic of North Ossetia-Alania. New isoenzyme serum assays for determining creatine kinase BB-isoenzyme and the transaminase activity in the spinal fluid are proposed, which may be used as potential markers in the biochemical diagnosis of Alzheimer's disease. They can both provide valuable information on the severity of morphological lesions of cerebral cells in Alzheimer's disease and serve as the basis for the differential diagnosis of different forms of dementia wherein dystrophic changes in CNS cells are absent or slightly pronounced.

Aged↗
PubMed1993

[The effect of chemically modified polyamine analogs on polyamine and putrescine biosynthesis in a cell-free test system from a rat hepatoma].

Nine novel chemically modified polyamine analogues were synthesized as potential antitumor agents and evaluated for their capacity to inhibit biosynthesis of polyamines in cell-free system of rat hepatoma G-27. All analogues (numbers I-IX) were used in a final concentration of 10(-4) M. Compounds I-VI modified by adenosine demonstrated activation both ODC activity (except substance I) and polyamine synthesis. The degree of activation depended on the length and quantity of methylene groups in the structure of the analogues. Compound I inhibited ODC activity stronger than its known inhibitor DFMO. On the other hand, substances VII-IX modified by two uracils significantly reduced polyamine levels as well as inhibited the ODC activity more effectively than DFMO. These results indicate that in cell-free system of rat hepatoma G-27 new analogues I and VII-IX are cap able of to some extent inhibiting biosynthesis of polyamines. These drugs might also be useful both as experimental approaches for investigation of peculiarities of polyamine metabolism, and possible application of these substances as antineoplastic agents.

Animals↗
PubMed1989

[Spectrophotometric method for determining the stability of lysosomes from animal tissues depending on the hydrogen ion concentration].

Rapid spectrophotometric method of lysosome stability determination depending on hydrogen ion concentration is described. The time of analysis is decreased by 5-6 h in comparison with enzymic method. The process of lysosome degradation was linear at pH 6. The incubation mixture acidity dependence curve of lysosome lysis extend was complex. The lysosome lysis rate rapidly increased at pH much less than 6 less than pH. Lysosome incubation at 0-4 degrees C during 24 h decreased its sensitivity to incubation mixture acidity within the whole investigated pH range. Isolated lysosome acid resistance may be used as an index of its stability and lability in vivo and in vitro by various physicochemical factors. Percentage of initial absorbtion (A520) and initial lysosome lysis rate (delta A520/min) may be index of such effect.

Absorption↗
PubMed1987

[Spectrophotometric method of determining the osmotic resistance of lysosomes isolated from animal tissue].

Rapid spectrophotometric determination of animal tissue lysosome osmoresistance is described. The duration of analysis is decreased by 5-6 h, as compared to enzymatic method. The process of lysosome degradation was linear at 0.7 M sucrose concentration. The dependence of sucrose molarity on the extent of lysosome lysis was complex. The lysosome lysis rate rapidly increased at sucrose molarity less than 0.7 M. Lysosome incubation at 0.4 degrees C for 24 h increased their osmotic sensitivity within the whole investigated osmotic pressure range. Isolated lysosome osmoresistance may be used as an index of dynamic structural and functional state of these particles and the extent of their degradation caused by various physical and chemical factors in vivo and in vitro. The measure of the initial absorption (A520) and the initial lysosome lysis rate (delta A520/min), as well as biological half-life may be the index of such an effect.

Animals↗
PubMed1986

[Effect of geomagnetic storms on the state of heart mitochondria and their role in providing energy for myocardial contraction].

The experiments on intact rabbits have shown that geomagnetic storm breaks the relationship between the size of myocardial mitochondria and the degree of cardiac contractility, causes swelling and further destruction of mitochondria. Geomagnetic storm leads to a decline in the left ventricular contractility. The development of geomagnetic storm is associated with a significant strong positive correlation between the size of mitochondria and the blood level of free fatty acids.

Animals↗
PubMed1986

[Fluorometric method of determining the activity of ornithine decarboxylase from animal tissues].

Fluorometric determination of ornithine decarboxylase activity is described. Dansyl putrescine fluorescence on TLC-plates was used to evaluate putrescine content in the samples. The dependence of dansyl putrescine fluorescence intensity on sample putrescine content was linear in the range of 0-120 nmol. Instrumental sensitivity coefficient (SF/C = 3), relative measurement sensitivity (Cmin = 0.3 nmol per sample), and basic metrological characteristics showing high reliability, accuracy and precision of enzyme activity determination were calculated. Standard error of the mean and relative standard deviation did not exceed 2.5 and 7.5%, respectively. Increased ODC activity was found in malignant and regenerating rat liver tissue, as well as in hepatomas H-27 and 48.

Animals↗
PubMed1986

[A rapid spectrophotometric method of determining heat-resistant lysosomes in animal tissues].

Rapid spectrophotometric method for the determination of thermoresistance in tissue animal lysosomes is described. The of analysis is decreased by 5-6 h, in comparison with enzymatic technique. The determination regimen was chosen in such a way that the process of lysosomal lysis was linear. The dependence of the incubation mixture temperature on the degree of lysosomal lysis was complex. The rate of lysosomal lysis rapidly increased at greater than 37 degrees C. Lysosome incubation at 0-4 degrees C for 24 h decreased its hypothermal (t = 10-30 degrees C), but not hyperthermal (t greater than 37 degrees C) sensitivity. Isolated lysosome thermoresistance may be used as an index of its stability and labialization in vivo and in vitro by various physico-chemical factors. The percentage of initial absorption (A520) and the initial rate of lysosomal lysis (delta A520/min), as well as melting temperature (Tmel) and biological half-life (t1/2) may be the measurements of such effect.

Animals↗
PubMed1977

[Oxidation of putrescine, spermidine and spermine by diamino-oxidase from mouse liver].

Optimal conditions to determine the activity of diaminooxidase in mouse liver homogenate are described. Maximal oxidation rate for putrescine was found to take place at a concentration of 20 mM and pH 9.5, and for spermidine and spermine--at 10 mM concentration and pH 9.2. The rate of tyramine oxidation was maximal at pH 7.8. Apparent KM values were 4.98-10(-3 M, 1-10(-3) M and 0.8-10(-3) M for putrescine, spermidine and spermine respectively. Hydroxylamine did not inhibit the rate of putrescin oxidation at optimal pH value.

Amine Oxidase (Copper-Containing)↗
PubMedDate not supplied

[Polyamine oxidative deamination in hepatomas with varying growth rates].

Rates of oxidative deamination of polyamines were studied in rapidly growing hepatomas G-22 and G-27, in slowly growing hepatomas G-60, G-61, G-48, G-46 as well as in liver tissue of tumor-bearing animals and animals treated with nitrose piperidine. Diamine oxidase activity was not found in rapidly growing hepatomas. Treatment with pyridoxal-phosphate did not restore the diamine oxidase activity in hepatomas G-27, but distinctly increased the latter in the liver tissue of the tumor-bearing animals up to the level of the enzymatic activity found in liver tissue of the intact animals. On the contrary, high concentrations of pyridoxal-phosphate (above 0.02 mg) inhibited the diamine oxidase activity in liver tissue of the impaired and intact animals. The enzymatic activity was markedly decreased in slowly growing hepatomas G-60, G-61, G-48 and G-46 as compared with the activity in liver tissue of tumor-bearing animals. Oxidation of all the substrates used could be measured using hepatoma G-60, putrescine and spermidine - for hepatoma G-61, but only putrescine - for hepatoma G-48. No of the substrates used was deaminated by hepatoma G-46. Four-fold decrease in the diamine oxidase activity was observed during malignization of liver cells induced by nitrose piperidine. The diamine oxidase was mainly localized in the postmitochondrial fraction of hepatocytes.

Amine Oxidase (Copper-Containing)↗
PubMedDate not supplied

[Supramolecular regulation of the activity of some oxidoreductases in the norm and in pathology].

Regulation metabolism in a cell is realised by enzymes arranged into supramolecular complexes. Lactate dehydrogenase (LDH) and alcohol dehydrogenase (ADH) are involved into formation of various supramolecular complexes. It is supposed that oxidoreductases LDH and ADH can form uniform functional supramolecular complex, exerting essential influence on redox potential of the cell.

Alcohol Dehydrogenase↗
PubMedDate not supplied

[Molecular mechanisms of metabolic adaptation in pathological changed liver during toxic hepatitis ].

Possible molecular mechanisms underlying changes in catalytical properties of alcohol dehydrogenase (ADH) and lactate dehydrogenase (LDH) were studied at toxic hepatitis. The development of toxic hepatitis is accompanied by significant changes in the activity of ADH and LDH assayed in subcellular fractions and kinetic characteristics of these enzymes. This can result in an increase cellular level of acetylaldehyde and lactate which promotes the development of liver cirrhosis.

Alcohol Dehydrogenase↗
PubMedDate not supplied

[Polyamines as biochemical markers of the antiproliferative effect of inhibitors of polyamine and putrescine biosynthesis enzymes in L-cell tissue cultures].

Effects of inhibitors of enzymes involved in biosynthesis of putrescine and polyamines on growth of mice C3H strain transformed fibroblasts as well as on the intracellular content of putrescine and polyamines were studied. Putrescine and polyamines were estimated as dansyl derivatives using HPLC. DL-alpha-difluoromethyl ornithine (F2MeOrn) and methyl glyoxalbis (quanyl hydrazone) (MGBG) were added to cultivation medium at final concentration 10(-4) M daily within 4 days. The cell culture was not treated within the following 3 days of the experiment. Distinct exceeding of spermidine content over concentrations of putrescine and spermine proved to be the specific property of L-cells growth in the culture. Amount of cells correlated strongly with intracellular content of spermidine and spermine (r = 0.964). Treatment of L-cells with F2MeOrn singly or in combination with MGBG led to 4- and 6-fold decrease in their growth rate, respectively. F2MeOrn altered content of polycations 2 days earlier in the cells which exhibited distinct correlation between putrescine and polyamines (r = 0.943). The rate of MGBG inhibition correlated distinctly with content of putrescine and polyamines (r = 0.953) as well as strong correlation between putrescine and polyamines content (r = 0.994) was detected after simultaneous effect of these inhibitors. This suggests that polyamines were involved in the antiproliferative action of the inhibitors studied and may be used as markers of cytostatics chemotherapeutic efficiency.

Animals↗
PubMedDate not supplied

[Spectrophotometric study of the physico-chemical properties of lysosomes isolated from rat liver].

Physico-chemical properties of intact lysosomes isolated from rat liver tissue were studied using spectrophotometric methods. The lysosomal suspension did not show specific maximal peaks in spectra of light passing through, scattering and absorbance. Stability of the suspension was most suitably evaluated at 520 nm. The rate of lysosomes lysis was distinctly increased at temperature above 37 degrees at pH below 3.0 and above 7.0 as well as in osmotic pressure (pi) exceeding 0.75 MPa. The temperature of phase conversion at 12.5 degrees and 38.5 degrees was calculated from Arrhenius plot. Activating energy of the lysosomes thermolysis was equal to 50, 2 and 18 kcal/mol for solid, mixed and liquid phases of lysosomal membranes, respectively. Additional incubation of the initial lysosomal suspension at 0-4 degrees within 24 hrs led to an increase in osmosis- and acid-stability within all the ranges of pi and pH values studies as well as to decrease of its sensitivity to hypothermia (10-30 degrees) but not to hyperthermia (above 37 degrees). Cadaverine at final concentration 1.0 and 0.1 mM protected lysosomes from thermolysis. Osmotic-resistance, acid-stability and thermotolerance may be used as available dynamic parameters of the particles structure state as well as in evaluation of deteriorating effects of various physicochemical factors in vivo and in vitro.

Animals↗
PubMedDate not supplied

[The characteristics of thermal action on the stability of liver lysosomes in rats].

The direct effect of temperature on the structural integrity of lysosomes was studied. Destruction of these particles was minimum in hypothermia but increased sharply in hyperthermia. A studied concentrated lysosome fraction proved to be heterogeneous in thermoresistance. The lysosome membranes started melting at 12.5 degrees C and melted completely at 38.5 degrees C. The results of the study show that the surrounding temperature may produce a direct damaging effect on the lysosomes, and support the assumption that the lysosomes play an important role as one of the key factors of the molecular mechanisms of the formation of a pathological condition in generalized hypo- and hyperthermia.

Animals↗
PubMedDate not supplied

[A modified highly sensitive spectrophotometric method for determining acid phosphatase activity in the animal liver].

A modified spectrophotometric procedure is described for estimation of acid phosphatase activity in rabbit liver tissue. Coefficient of instrumental sensitivity (SA/C = 0.029), apparent molar absorption (epsilon 820 = 30,500), relative sensitivity of measurement (Cmin = 0.18 mM) were calculated as well as main metrological patterns were evaluated, which showed that the procedure was highly sensitive, accurate and reproducible. Standard error did not exceed 1% and standard deviation was not above 5%.

Acid Phosphatase↗