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D Dobrota

Publications and source records attributed to D Dobrota.

At least 19 recordsLinked to original sources
PubMed2000

Carnosine protects rats under global ischemia.

Rat brain subjected to 45-min global ischemia is characterized by decreased activity of K-p-nitrophenyl phosphatase and monoamine oxidase B and a disordering of the membrane bilayer by reactive oxygen species attack, the latter being monitored by the fluorescence of the membrane fluorescent probe, 1-anilino, 8-naphtalene sulphonate (ANS). Ischemic injury resulted in 67% mortality of the animals. In the group of animals pre-treated with the neuropeptide carnosine the mortality was only 30%. At the same time, carnosine protected both the activity of the above-mentioned enzymes and the brain membrane disordering, which was also tested by ANS fluorescence. The conclusion was made that carnosine protects the brain against oxidative injury and thereby increases the survival of the animals.

4-Nitrophenylphosphatase↗
PubMed2000

Preface

Explore the source record for details and available documents.

Journal Article↗
PubMed2000

A study of creatine kinase reaction in rat brain under chronic pathological conditions-chronic ischemia and ethanol intoxication.

Creatine kinase reaction rates were measured by the magnetisation transfer technique in brains of healthy adult and aged rats and in rats with chronic cerebral ischemia and chronic ethanol intoxication. These measurements indicated that the rate constant of the creatine kinase reaction is significantly reduced in the case of severe chronic cerebral ischemia in aged rats. In the adult rats, during chronic ethanol intoxication after 3 weeks of administration of 3 ml of 30% ethanol once a day via a gastric tube, a significant decrease in the pseudo first-order rate constant k(for) of the creatine kinase reaction was also found. In contrast, mild chronic cerebral ischemia in adult rats produced an increase in the reaction rate 4 weeks after occlusion. At the same time, corresponding conventional phosphorus magnetic resonance spectra showed negligible changes in signal intensities.

Adenosine Triphosphate↗
PubMed2000

Anti-ischemic activity of carnosine.

This review summarizes the data on anti-ischemic activity of carnosine. The pronounced anti-ischemic effects of carnosine in the brain and heart are due to the combination of antioxidant and membrane-protecting activity, proton buffering capacity, formation of complexes with transition metals, and regulation of macrophage function. In experimental cerebral ischemia, carnosine decreases mortality and is beneficial for neurological conditions of the animals. In cardiac ischemia, carnosine protects cardiomyocytes from damage and improves contractility of the heart. The data indicate that carnosine can be used as an anti-ischemic drug.

Animals↗
PubMed1999

Na/K-ATPase under oxidative stress: molecular mechanisms of injury.

1. The authors compare oxidative injury to brain and kidney Na/K-ATPase using in vitro and in vivo approaches. The substrate dependence of dog kidney Na/K-ATPase was examined both before and after partial hydrogen peroxide modification. A computer simulation model was used for calculating kinetic parameters. 2. The substrate dependence curve for the unmodified endogenous enzyme displayed a typical curve with an intermediate plateau, adequately described by the sum of hyperbolic and sigmoidal components. 3. The modified enzyme demonstrated a dependent curve that closely approximates normal hyperbola. The estimated ATP K(m) value for the endogenous enzyme was about 85 microM; the Kh was equal to 800 microM. The maximal number of protomers interacting was 8. Following oxidative modification, the enzyme substrate dependence curve did not show a significant change in the maximal protomer rate Vm, while the K(m) was increased slightly and interprotomer interaction was abolished. 4. Na/K-ATPase from an ischemic gerbil brain showed a 22% decrease in specific activity. The maximal rate of ATP hydrolysis by an enzyme protomer changed slightly. but the sigmoidal component, characterizing the enzyme's ability to form oligomers was abolished completely. The K(m) value was almost unchanged, but the Hill coefficient fell to 1. These data show that Na/K-ATPase molecules isolated from the ischemic brain have lost the ability to interact with one another. 5. We suggest that the most important consequence of oxidative modification is Na/K-ATPase oligomeric structure formation and subsequent hydrolysis rate suppression.

Animals↗
PubMed1999

Carnosine: an endogenous neuroprotector in the ischemic brain.

1. The biological effects of carnosine, a natural hydrophilic neuropeptide, on the reactive oxygen species (ROS) pathological generation are reviewed. 2. We describe direct antioxidant action observed in the in vitro experiments. 3. Carnosine was found to effect metabolism indirectly. These effects are reflected in ROS turnover regulation and lipid peroxidation (LPO) processes. 4. During brain ischemia carnosine acts as a neuroprotector, contributing to better cerebral blood flow restoration, electroencephalography (EEG) normalization, decreased lactate accumulation, and enzymatic protection against ROS. 5. The data presented demonstrate that carnosine is a specific regulator of essential metabolic pathways in neurons supporting brain homeostasis under unfavorable conditions.

Animals↗
PubMed1998

Creatine kinase reaction rates in rat brain during chronic ischemia.

Creatine kinase reaction rates were measured by magnetisation transfer technique in the brain of healthy adult and aged rats and in the rats with mild or severe chronic cerebral ischemia. These measurements indicated that the rate constant of the creatine kinase reaction is significantly reduced in the case of chronic brain ischemia in aged rats. In contrast, occlusion of both carotid arteries in adult rats produced a slight increase in the reaction rate 4 weeks after occlusion. At the same time, corresponding conventional phosphorus magnetic resonance spectra showed negligible changes in signal intensities.

Aging↗
PubMed1998

Endogenous digoxin-like immunoactivity in subjects with diabetes mellitus and hypertension.

The serum concentrations of digoxin-like immunoactivity (DLIA) were measured in 99 patients: 20 healthy volunteers (HV), 15 patients with insulin-dependent diabetes mellitus (IDDM), 14 patients with non-insulin-dependent diabetes mellitus without hypertension taking oral hypoglycemic (OHA) agents (NIDDM/-HT), 11 patients with NIDDM without hypertension taking insulin (NIDDM/-HT+INS), 12 NIDDM patients with hypertension taking OHA (NIDDM/+HT), nine NIDDM patients with hypertension taking insulin (NIDDM/+HT/+INS), 10 patients with essential hypertension with normal insulin levels (HT/-HI), and in eight patients with essential hypertension with hyperinsulinemia (HT/+HI). The numbers (%) of subjects with DLIA levels above the detection limit of the assay used (> 0.1 nmol/L) were, in the NIDDM/-HT group, 12/14 (85.7%) and in the NIDDM/+HT group, 9/12 (75%), significantly higher (P < .05) than in the HV (7/20; 35%), IDDM (3/15; 20%), and HT/-HI groups (2/10; 20%). The number and percentage of subjects with DLIA levels above the detection limit in the HT/+HI group was six of eight (75%), significantly (P < .05) higher than in the IDDM and HT/-HI groups, and tended to be higher than in the HV group (P < .055). Means and SD of serum DLIA levels (nmol/L) in the NIDDM/-EH (0.18/0.09) and NIDDM/+EH (0.19/0.15) groups were significantly higher (P < .05) than in the HV (0.09/0.07), IDDM (0.05/0.05), and EH/-HI (0.06/0.06) groups. DLIA levels in the HT/+HI group (0.15/0.12) were significantly higher (P < .05) than in the IDDM and HT/-HI groups. The percentage of DLIA levels above the detection limit, as well as the mean and SD of DLIA in the NIDDM group taking OHA, did not differ from those in subjects taking insulin. In all subjects studied (n = 99), DLIA correlated with C-peptide (r = 0.30; P < .01) and glomerular filtration (GF) (r = -0.21; P < .05). After exclusion of insulin-treated patients, DLIA correlated significantly with plasma glucose (PG; r = 0.25; P < .05), immunoreactive insulin (IRI; r = 0.41; P < .001), C-peptide (r = 0.27; P < .05), and GF (r = -0.26; P < .05) (n = 64). Correlation of DLIA with IRI (r = 0.33; P < .05; n = 38) also persisted after exclusion of patients taking insulin and those with DLIA levels below the detection limit. Similarly, DLIA also correlated with C-peptide (r = 0.64; P < .05) and IRI (r = 0.70; P < .05) in the subgroup of 10 patients with the highest levels of DLIA (> 0.25 nmol/L). None of the sera (n = 15) with different DLIA concentrations (0.0-0.38 nmol/L) exhibited K-pNPPase (Na+-K+-ATPase) inhibitory activity. In conclusion, this work demonstrated elevated serum DLIA in NIDDM and HT/+HI patients, and its correlation with IRI and GF. However, due to the fact that the chemical nature and biologic properties of DLIA are still a matter of debate, it is too early to speculate whether the elevation of DLIA is just a secondary result associated with HI and reduced GF, or whether it also has pathophysiologic consequences. Nevertheless, in both cases the elevated concentrations of substances with DLIA and their interference with antidigoxin antibodies may affect therapeutic monitoring of digitalization in NIDDM and HT/+HI patients. Also, the elevated DLIA could subclassify these patients. The significance of such subclassifications (pathophysiologic, therapeutic, or prognostic), however, will need further investigation.

Adult↗
PubMed1998

[The effect of ischemia and ischemia-reperfusion on ion transport systems].

Interruption of cerebral blood flow leads to dissipation of ionic gradients as the consequence of ionic channel overstimulation and ionic pump failure. The aim of this work was to study the possible effects of ischaemia and ischaemia followed by reperfusion on biochemical properties of endoplasmic calcium pump and synaptosomal sodium pump and sodium/calcium exchanger. The results presented in this study showed that 15 minute ischaemia led to the inhibition of all three ionic transport systems, however in different degrees. 60 minute reperfusion following 15 minute ischaemia led to partial recovery of calcium pump and sodium/calcium exchanger. The activity of sodium pump was still significantly depressed. Ischaemia and ischemia followed by reperfusion did not affect kinetic parameters of calcium pump. On the other side, both ischaemia and ischaemia-reperfusion led to an increase of sodium pump affinity to ATP and a decrease of the enzyme affinity to potassium. The possible causes of the changes, as the alteration of membrane structure or altered enzymes phosphorylation are discussed in the study. In addition to the inhibitory effect of ischaemia-reperfusion injury, intracellular water accumulation, as the possible consequence of altered ion homeostasis, is documented by nuclear magnetic resonance (imaging).

Animals↗
PubMed1995

[Study of malignant melanoma using 1H-nuclear magnetic resonance spectroscopy].

1H-nuclear magnetic resonance spectroscopy was used to study malignant melanoma extract. The aim of this work was to study low molecular weight metabolites soluble in water, which can be helpful for a more detailed understanding of tumor metabolism with a view to using this knowledge for diagnosis. The authors found in a well distinguished spectrum the presence of numerous low molecular weight metabolites such as glutamate, glutamine, choline, inositol, creatine, phosphocreatine, phosphocholine, glucose, acetate, alanine, lactate. It is necessary to correlate these in-vitro findings with a study of the above mentioned metabolites in-vivo. Malignant melanoma is appropriate for this investigative and diagnostic technique because of its superficial localization. (Fig. 1, Ref. 18.)

Humans↗
PubMed1995

[Morphologic study of mastocytes from skin biopsies in patients with non-systemic and systemic mastocytosis].

The authors describe morphologic changes in mastocytes in the picture of transmission electron microscopy (TEM) and skin changes in patients with urticaria pigmentosa (7 causes) and systemic mastocytosis (2 causes). The presented study analyzes the changes in the cellular membrane and cytoplasmic processes, intracytoplasmic membrane structures, mitochondria, granules, and nuclei of mastocytes in patients with systemic mastocytosis. The authors evaluate these cells as being atypical, respectively immature. The study discusses the malignization of these states. (Tab. 2, Fig. 8, Ref. 16.)

Biopsy↗
PubMed1994

[Interaction of cholesterol and sphingomyelins in membranes of the sarcotubular system after denervation].

We investigated the content of cholesterol and phospholipids in the sarcotubular membranes from the rabbit fast-twitch muscle in various time intervals after the section of sciatic nerve. Along with the unchanged content of total phospholipids we found an increase of cholesterol in all investigated intervals. Significant elevation of cholesterol by about 33.8% following 14 days of denervation is associated with a three-times higher level of sphingomyelins. The elevated level of sphingomyelins persists after 28 days and the molar ratio cholesterol/phospholipids is 2.6 times higher in comparison with the control group. Investigation of cholesterol synthesis on muscle slices from the precursor 14C-mevalonic acid as well as of the activity of HMG-CoA reductase have shown that the cholesterol increase following denervation is not in correlation with its synthesis de novo. Similarly it has been shown that an increase of membrane cholesterol is not linked with the change of membrane fluidity (Tab. 3, Fig. 3, Ref. 30.)

Animals↗
PubMed1993

[The role of platelet activating factor in the pathogenesis of asthma].

The work reviews knowledge about the function of PAF, the presupposed mediator of asthma. The PAF mediator evokes contraction of smooth muscles of respiratory passages, too in vivo as in vitro, by means of an indirect mechanism involving activated platelets which function as intermediaries. The constrictor released due to this process can be represented by histamine or a product of arachidonic acid. Mucous secretion is according to current knowledge stimulated by PAF. The PAF mediator appears to be a considerable chemotactic factor for eosinophils which by their cytotoxic effects on respiratory epithelium support the origin and development of bronchial hyperresponsiveness. PAF has an eminent effect on the growth of microvascular permeability. Antagonists of PAF inhibit some mentioned PAF effects. Their possible therapeutic utilization, excluding ketotiphen, are currently subjected to research. (Fig. 2, Ref. 17.).

Asthma↗
PubMed1992

[Carnosine and anserine in working muscles--study using proton NMR spectroscopy].

NMR spectroscopy was used to study carnosine and anserine metabolism in rat tissues under intensive muscle loading. Muscle loading was accompanied by the dipeptide (predominantly anserine) accumulation in muscle tissues. Preliminary per os administration of carnosine (250 mg/kg of body mass) did not increase the dipeptide content in muscle tissues but diminished the lactate content in rat muscles under intensive muscle loading.

Animals↗
PubMed1991

Effects of denervation on the contents of cholesterol and membrane systems involved in muscle contraction in rabbit fast-twitch sarcotubular system.

Denervated fast-twitch rabbit muscles were progressively losing their fresh weight and the yield of sarcotubular protein was increasing. The activity of Ca(2+)-ATPase was affected but very slightly, the basal Mg(2+)-ATPase and the Mg(2+)-ATPase/Ca(2+)-ATPase ratio however increased together with a simultaneous depression of the membrane-bound acetylcholinesterase activity. We did not observe any differences in density properties of sarcotubular fractions between control and denervated muscle. However, a relative enrichment in SM and H fraction could be seen after denervation with small changes in the content of the Ca(2+)-pump protein, increased levels of calsequestrin and cholesterol, mostly in the heavy and the SM fraction. After denervation the binding sites for 3H-PN-200-110 did not show any changes in receptor affinity, but the number of putative Ca(2+)-channels increased twice along with a depression of 3H-ouabain binding sites. We suggest that the denervation of fast-twitch muscle leads to the hypertrophy of the junctional sarcoplasmic reticulum and the T-system. Changes in the cholesterol content, in the number of putative Ca(2+)-channels and in Na+, K(+)-ATPase can affect the muscle contraction.

Acetylcholinesterase↗