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Results for “POLAROGRAPHY”

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PubMed1978

In vitro and in vivo inhibitory effect of dehydroepiandrosterone on respiration.

The inhibitory effect of dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulphate (DHEA-S) was tested either in vitro with the use of Clark electrode combined with polarography or in vivo using the Spirolyt apparatus. In vitro, DHEA and progesterone showed a marked inhibitory effect on oxygen consumption by the rat heart liver mitochondria. A decrease of oxygen consumption was also observed with electron transporting particles (ETP). However, in both instances DHEA-S was without effect. In vivo, DHEA inhibited whole body oxygen consumption in rats, provided the steroid was injected in a dose of 50 mg kg-1 and 1--16 h before the measurement. No effect was obtained 9 h after DHEA injected in a dose of 5 mg kg-1. Also DHEA administered per os (25 mg kg-1) for six days was without effect as measured 16 h after the last dose. These data are discussed in connection with the beneficial effect of DHEA-S administered to patients with angina pectoris.

Animals↗

PubMedDate not supplied

[Myocardial energy metabolism in decimeter-wave exposures].

Decimeter waves (460 MHz, 10 or 120 mW/cm2) were applied to the area of the heart, thyroid, adrenals and hypothalamus-hypophysis of rabbits with myocardial ischemia. As shown by polarography of energy metabolism in the cardiomyocytic mitochondria, an optimal energetic effect was achieved in the thyroid exposure (120 mW/cm2), while maximal stimulation of the mitochondrial respiration took place in the cardiac exposure (10 mW/cm2).

Adrenal Glands↗

PubMed2005

Evaluation of microcirculation in elderly patients with venous trophic ulcers.

Altogether 112 patients over 50 years of age suffering from varicosity and chronic trophic ulcers of the distal limb segments were examined. The work was based on an analysis of the microcirculatory flow in lower limb tissues (laser Doppler flowmetry, BLF 21 system, Transonic Systems Inc., USA) and on the evaluation of tissue metabolism by measuring partial oxygen and carbon dioxide tension (percutaneous polarography; TCM-3 system, Radiometry Company, Denmark). The postischemic and orthostatic tests were used to assess the functional microcirculatory reserve. The data obtained indicate local tissue hypoxia in elderly patients with venous trophic ulcers associated with an increase of the basal flow only in the lower third of the leg. Venous trophic ulcers are marked by a significant reduction of partial oxygen tension in the tissues adjacent to the area of trophic ulcers to 4.3+/-0.5 mm Hg on the average in the presence of the low functional microcirculatory reserve. Local tissue hypoxia in the area of trophic ulcers, which develops despite an increase of blood inflow to the microcirculatory bed evidences inhibition of tissue flow and activation of the arterio-venular bypasses. The results obtained in the course of the study allow to optimize the treatment policy in elderly patients suffering from venous trophic ulcers. In addition to the measures lowering venous hypertension, the treatment should include correction of microcirculatory disorders, which is to be carried out in the pre- and postoperative periods.

Aged↗

PubMed1991

AC-polarographic quantitation of tolmetin sodium.

Fundamental harmonic alternating current polarography has been described for the determination of tolmetin sodium and its capsules, (Tolectin-200 mg). The AC procedure was applied by superimposing 10 mV, rms, AC voltage on a DC ramp in the range -1200 to -1450 mV at a frequency of 50 Hz in acetate buffer of pH 5.0 containing 0.001% gelatin as a maxima suppressor. A three electrode assembly consisting of dropping mercury electrode (dme) and two Ag/AgCl/KCl (sat.) electrodes was employed. Mercury flow rate was 3 mg sec(-1) under a corrected head pressure of 80 cm. The electrode reaction was investigated by Kalousek K1 and K2 techniques which indicated the non-reversibility of the electrode process on the AC time scale. The percent result obtained by standard addition procedure was 101.4 +/- 2.0 for tolmetin sodium capsules.

Journal Article↗

PubMed2006

[Role of peroxidation processes and nitric oxide in mechanisms of paraneoplastic alterations of hemocirculation].

The present work was aimed to study mechanisms of paraneoplastic alterations of tissue redox-status, intensity of local blood flow in liver and their possible interrelations in case of malignant tumor growth. It has been investigated the electronic paramagnetic centres of blood and liver using the electronic paramagnetic resonance (EPR) method and intensity of local hemocirculation with the use of H(+) clearance polarography method. Experiments have been carried out on adult white rats of mixed population with carcinoma Walker and mice -- with carcinoma Ehrlich. It has been shown that malignant tumor growth displays conditions that lead to exaggerated lipid peroxidation (production of POL promoters -- Fe(2+), Mn(2+), NO, ubiquinone) and suppression of antioxidant protection of organism (reduction of total ceruloplasmin concentration in blood and increased concentration of oxidized ceruloplasmin). It has been suggested that in case of malignant tumor growth sharp paraneoplastic alterations of redox-status plays essential role in mechanisms of paraneoplastic disorders of tissues blood supply. All of these interrelated processes result in generalized paraneoplastic hypoxia in organs and tissues.

Animals↗

PubMed2005

Toxicity of the ammonium nitrate NH4NO3 on the respiratory metabolism of three biological models: parameciums, mosses and lichens.

The inopportune throws out of diverse substances in the atmosphere, constitutes without any doubt the obvious of environmental pollution by man. Among these substances, we are interested in the ammonium nitrate NH4NO3, nitrate fertilizers widely used in farming in our region - Annaba located in the eastern part of Algeria - and manufactured in the same region. In fact, the excessive fertilization, the intensive spreading of animal faeces and the industrial pollution are the accumulation sources of nitrate in vegetables, drilling and the underground waters. The goal of this study is to show the obviousness of a possible toxic effect of NH4NO3 on paramecium an inferior plants resed as biological models. The tests of toxicity were achieved on samples of the area of culture of parameciums. Four concentrations were chosen: 10, 20, 30 and 40 mM, and added before and after appearance of the parameciums in the area. The prepared solutions with the same concentrations of NH4NO3, were used for the dampening of the samples of mosses and lichens. The use of an original technique the polarography allowed us to measure the quantity of oxygen consumed by the organisms in presence of the polluent. The results show that: (i): The treatment by NH4NO3 stimulates the respiratory metabolism of paramecium, (ii): with mosses as well as the measure of the consumption of the oxygen shous the abviousness contrasted with a dampening of respiration but also of the photosynthesis. The perturbation of the respiration and photosynthesis of mousses and lichens can explain the degradation of the plant material and the disappearance of certain species from our ecosystem.

Animals↗

PubMed1991

[The microcirculation of patients with arterial ischemia of the lower extremities during laser therapy].

Microcirculation in the patient's foot skin with different stages of arterial ischemia, was examined with the aid of TV-capillaroscopy, laser dopplerography, polarography of transcutaneous oxygen tension. The effect of semiconductor laser (wave length 0.98 mcm) on microcirculation system was studied. The dependence of capillary blood flow on the transcutaneous oxygen tension was determined. The laser therapy proved to be successful in the patients with the II and III stages of arterial ischemia.

Adult↗

PubMedDate not supplied

[The use of the electrophoresis of water-insoluble preparations of fencarol and parmidine from dimexide solutions].

Hepatic mitochondrial respiration was recorded by polarography in various metabolic states using relevant substrates and inhibitors in rat male experiments in vivo and in vitro. The above measurements were made following electrophoresis of parmidine and phencarol in 50% dimexide solution. Parmidine from dimexide solution proved indifferent to mitochondrial energy apparatus, while phencarol could inhibit NADH-dehydrogenase link of the respiratory chain and arrest dimexide inhibition of succinate oxidase system. The findings provided a basis for therapeutic procedures which were tested in 105 patients. The immediate response of coronary and neurodermatitis patients appeared satisfactory.

Adolescent↗

PubMed2006

Mutagenic and carcinogenic potential of menadione.

Menadione (2-methyl-l,4-naphthoquinone) or vitamin K3 is a lipid-soluble substance and promotes the hepatic biosynthesis of blood clotting factors. Carcinogenic potential of menadione was determined by a DC polarography method in strictly anhydrous N,N-dimethylformamide (DMF) in the presence of alpha-lipoic acid. Superoxide anion formation was measured after incubation of rat lung, liver and kidney microsomes with menadione. The genotoxic potential of menadione was investigated using the unscheduled DNA synthesis (UDS) and alkaline elution assays. The parameter of potential menadione carcinogenicity tg alpha was 0.0025 indicating no carcinogenic activity of menadione. Superoxide anion was generated in a concentration- and time-dependent manner when menadione was incubated with microsomes. In the mammalian cells (A 549) used for alkaline elution and UDS assays, menadione was cytotoxic at concentrations above 20 nmol/ml. The use of S9 mix (metabolic activation) fractions decreased the cytotoxicity of menadione. In the concentration range of above 20 nmol/ml menadione was genotoxic in the UDS test in absence of metabolic activation. In the presence of metabolic activation the menadione-induced DNA damage and repair was greatly reduced. Treatment of A 549 lung cells with 4-nitroquinoline-N-oxide (NQO) caused significant formation of DNA single-strand breaks both in the absence and presence of metabolic activation. Treatment of A 549 lung cells with menadione caused formation of DNA single-strand breaks in the absence of S9 mix. In the presence of metabolic activation menadione caused no significant formation of DNA strand breaks. Menadione-induced DNA repair in A 549 cells was concentration-, time-, and temperature- dependent. Measurement of unscheduled DNA (UDS) synthesis (repair) following treatment with NQO and menadione yielded strong UDS responses in the absence of S9 mix. Taken together the results of these studies suggest the mutagenic potential of NQO and menadione. These results indicate that menadione undergoes redox cycling with formation of reactive oxygen species which cause DNA damage and repair without having a carcinogenic potential.

Animals↗

PubMedDate not supplied

[Conformational characteristics and packing of endogenous lipid fractions of transcriptionally active and repressed chromatin].

The fluorescence and polarography methods are used to establish certain differences in conformation characteristics of transcriptionally active and repressed forms of rat liver chromatin. The data obtained prove the nucleo-soma ability to aggregation in the repressed chromatin and confirm a decondensed character of packing in transcriptionally active chromatin. It is supposed that these peculiarities are connected with different content of calcium and iron ions in the studied fractions of chromatin. Lipids, being the components of chromatin fractions, are packed with proteins in a form of bilayer structure. The packing character is similar in the both chromatin fractions. But microviscosity of the lipid bilayer in transcriptionally active chromatin is significantly lower than that in the repressed one and this may be one of reasons of different transcriptional activity and ability to peroxidation of the studied chromatin forms.

Animals↗

PubMed1991

[Organ transplantation. One of the biochemical reasons for the race against the clock].

The authors have studied the subcellular functioning of human adrenal glands removed from subjects in a stage IV coma. The present study has a two-fold interest: on the one hand, it offers biochemical information on a key element in the intermediate metabolism (namely, the mitochondrial energetic metabolism, occurring in a fragile tissue which, under a state of shock, is primarily affected; the results obtained on such type of tissue may therefore be inferred to other organs); on the other hand, it allows a wider approach of the adrenal biochemical mechanisms during a stage IV coma. The mitochondrial fraction was obtained by differential centrifugation carried out immediately after organ removal. The steroid synthesis, studied using radioactive precursors, turned out to be similar to that found in other mammals. Respiratory characteristics, determined by polarography with a Clark oxygen electrode, at 37 degrees C, were satisfactory: respiratory intensity was 77.25 +/- 12.16 nanomoles O2/min/mg mitochondrial protein in the presence of succinate 15 mM and respiratory control was 1.93 +/- 0.15 in the presence of ADP 37 microM. The respiratory chain functioned in a classical manner: rotenone 25 microM did not inhibit respiration in the presence of succinate 15 mM, while it did with L-malate 15 mM. In the presence of succinate 15 mM, the respiratory intensity was inhibited at 87.4 percent and 76.7 percent by KCN 0.01 microM and antimycin A 0.09 microM respectively; with DNP 85 microM, it was multiplied by 5. However, the value of the P/O ratio was low (0.24 +/- 0.04). Under the present conditions, this may highlight the difficulty to synthetize ATP whenever neither the functioning nor the regulation of the multi-enzymatic complex accounting for oxygen consumption are affected. This result clearly confirms that the shortest possible delay between organ removal and transplantation is crucial, as the renewal of cell structures requires energy. These fundamental research studies account for the major concerns of reanimation teams. This also raises the issue of the role of fundamental researchers within a transplant surgery team.

Adenosine Triphosphate↗

PubMedDate not supplied

[Changes in the cerebral hemodynamics under the influence of piracetam and fenibut during motion sickness].

In the experiments on conscious rabbits with the electrodes implanted in the brain it was found by the methods of hydrogen clearance and polarography that piracetam (50 and 500 mg/kg) and phenibut (50 mg/kg) induced a decrease of the local blood flow in the cortex of the frontal, temporal and occipital regions and the total cerebral blood flow. The administration of the drugs before tilting prevents the occurrence of vasodilatation in the brain and results in a decrease of the blood flow in the cortex and in the confluence of the cerebral venous sinuses that is thought to be connected with the mechanism of an increase of the vestibular stability under the influence of GABA derivatives.

Animals↗

PubMedDate not supplied

[Analysis of inhibition in pathways of NADP.H2 and NAD.H2 oxidation in liver tissue microsomes].

Microsomal complexes of electron transfer were resistant to typical inhibitors of mitochondrial pathway of electron transport. In oxidation of NADP.H2 there were at least three point of molecular O2 reduction: NADP.H2-specific flavoprotein, Fe2+ participating in reactions of peroxidation of unsaturated fatty acids and cytochrome P-450. Efficiency of cytochrome P-450 inhibitors could not be evaluated by polarography as in the pathway several sites of molecular O2 activation were observed. In oxidation of NADP.H2 estimation of the rate of electron transfer reactions was carried out by monitoring of velocity of O2 absorption in presence of EDTA (inhibitor of the reaction of peroxidation) because about 50% of the total oxygen were utilized only in the process where NADP.H2 was oxidized. NAD.H2 oxidation, inhibited with EDTA, was activated by addition of Ca2+.

Animals↗

PubMed1990

Inhibition of ATP synthesis by 1-methyl-4-phenylpyridinium ion (MPP+) in mouse brain in vitro and in vivo.

The effects of the MPP+ ion on ATP synthesis were studied using mouse brains in vitro and in vivo. Oxidation of glutamate + malate in mitochondria estimated by polarography was significantly inhibited by MPP+, and synthesis of ATP was inhibited to approximately one-third of that of control by 0.05 mM of MPP+. Oxidation of alpha-glycerophosphate and succinate was not inhibited, and ATP was synthesized normally. In cerebral mitochondria of mice treated with 40 mg/kg of MPTP, oxidation of glutamate, pyruvate, and malate was also significantly inhibited, but ATP was synthesized in normal amounts. This inhibition was prevented by pretreatment of mice with pargyline. Our observation would give further support for the mitochondria hypothesis of the mechanism of neuronal degeneration in MPTP-induced parkinsonism.

1-Methyl-4-phenylpyridinium↗

PubMedDate not supplied

[The diagnosis of nerve trauma late].

On the basis of examination of 110 patients with sequelae of incised damages to 146 nerves, the author compared the clinical data and the results of electroneuromyography, thermography, polarography, and the ninhydrin test to appraise the anatomical condition of the nerve trunks. Electroneuromyography is a sensitive method in determining the indications for operation, but is insufficiently informative for making the differential diagnosis of intratruncal neurinomas. Complex clinico-instrumental study of the pulsed (electroneuromyography) and the trophic function proper of the nerves (evaluation of microcirculation, thermotopography, and perspiration of the autonomous zones of innervation) allows their preoperative condition to be evaluated more fully.

Electrophysiology↗

PubMed1990

Use of myocardial skinned fibres for the study of mitochondrial oxidative phosphorylation during ischaemia.

The authors studied mitochondrial oxidative phosphorylation in the skinned myocardial fibres of the rat and the rabbit during ischaemia. Saponin action on tissue was used to remove the sarcolemma while leaving the interior of intracellular structures intact. Mitochondrial oxidative phosphorylation was measured by polarography using Clark's oxygen electrode in the presence of NAD- and FAD-substrates. The skinned fibre method is rapid and very simple. The fact no more than 5-10 mg of tissue is needed to perform it makes it suitable for the study of metabolic processes in experimental and clinical cardiology, under physiologic conditions as well as during ischaemia.

Animals↗

PubMed1990

[Measurement of oxygen concentration in tumor cells by fluorescent probe (nitrocompound)].

The hypoxic cell fraction in tumors is considered to be responsible for radioresistance. Estimating the population of the hypoxic cell fraction in tumor could develop the effective means to predict radiosensitivity. In this study, nitroacridine (fluorescent dye) was tested to estimate hypoxic status in single cells and in spheroids. The oxygen concentration in the medium was measured by oxygen electrodes utilizing polarography method, mean while that in cells was calculated from the fluorescence intensity of the dye. The fluorescent spectra from cells showed the same pattern in spite of the changed oxygen concentration in medium, on the other hand its intensity was dependent upon the oxygen concentration. Using a fixed nitroacridine concentration and a fixed staining time, oxygen concentration of cells could be determined within range from 0.1 to 1.0% values. These values are almost the same as the oxygen concentration of the radioresistant tumor cells. Thus, the fluorescent method we used in this study is considered to be useful to estimate radioresistance of tumor. However, fluorescent intensity would alter when used different cell lines, because of different cellular activity of nitroreductase.

Aminacrine↗

PubMed1990

[Relation between functional-immunological and clinical parameters in juvenile periodontal diseases].

In 57 Moscow adolescents aged 15 to 19 years gingival bleeding and periodontal pocketing was recorded. In addition to this functional parameters of Rheoperiodontography and Polarography were documented and immunological investigations were carried out. The clinical parameters of the test group showed a higher level of periodontal diseases compared with a random selected control group. A correlation between clinical and functional parameters in early periodontal destruction was not detected. This study demonstrates the importance of prevention of periodontal diseases in adolescents.

Adolescent↗