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Biomedical subjects

D Bartos

Publications and source records attributed to D Bartos.

18 recordsLinked to original sources
PubMed1992

Chronic hyperdynamic sepsis in the rat. II. Characterization of liver and muscle energy metabolism.

Sepsis was induced in male rats by injections of live Escherichia coli No. 4 (or E. coli No. 3) and Bacteroides fragilis organisms into a preformed subcutaneous abscess. Body weight, food and water intake, and cardiac output were measured daily. After 1, 2, or 3 weeks, animals were sacrificed, and blood, liver, and muscle were collected for measurements of plasma glucose and carnitine, mitochondrial respiratory activity, mitochondrial cytochrome concentrations, and tissue adenine nucleotides. Compared with sham controls, no significant differences were found in state 3 respiratory activities of liver mitochondria isolated from rats with moderate (no weight loss, cardiac output increased to 150% of control) or severe (0.5% weight loss/day, cardiac output increased to 200% of control) sepsis at any time. After 1 week of severe, but not moderate, sepsis, pyruvate-supported respiration in muscle mitochondria was significantly decreased, while branched-chain ketoacid and beta-hydroxybutyrate-supported respiration remained unchanged. After 2 weeks of severe, but not moderate, sepsis, beta-hydroxybutyrate and branched-chain ketoacid oxidation increased severalfold; pyruvate utilization remained depressed. Severe or moderate sepsis did not uncouple mitochondrial respiration at any time. Total muscle carnitine concentration was significantly decreased after long-term but not short-term severe sepsis. Severe short-term sepsis caused a significant increase in liver short-chain acyl and total carnitines. Muscle energy charge was unaltered by either moderate or severe sepsis. These results represent the first demonstration of sepsis-induced fuel shifts at the mitochondrial level in muscle: Severe hyperdynamic sepsis is characterized by the reduced ability of muscle mitochondria to utilize pyruvate with a simultaneous increase in branched-chain ketoacid and ketone body utilization. These changes were not observed in liver mitochondria.

Adenine Nucleotides↗
PubMed1992

[Changes in the visual field after laser coagulation in type I diabetics].

The authors examined 41 eyes of 22 compensated type I diabetics 1 - 2 years after laser photocoagulation, using an automatic static perimeter Peritest. One fifth of the investigated patients had marked changes - DR20. The patients are not aware of the diminution of the visual field. Even the most extensive diminution of the visual field in this group did not restrict the ability to drive motor vehicles.

Adult↗
PubMed1991

Mechanism of peroxide-induced cellular injury in cultured adult cardiac myocytes.

Reactive oxygen species contribute to the tissue injury seen after reperfusion of ischemic myocardium. We propose that toxicity originates from the effect that mitochondrial peroxide metabolism has on substrate entry into oxidative pathways. To support our contention, cultured adult rat cardiomyocytes were incubated with physiological concentrations of peroxide. The cellular extract and incubation medium were analyzed for adenine nucleotides and purines by reverse-phase high-pressure liquid chromatography. Cellular glutathione efflux was determined by enzymatic analysis of the incubation medium. Pyruvate dehydrogenase (PDH) activity was determined in the cultured myocytes as well as in freshly isolated cardiac mitochondria using [1-C14]pyruvate. Extracellular glutathione rose 3.3-fold in response to small doses of peroxide (approximately 108 nmol/mg protein). Likewise, small quantities of peroxide reduced total cellular adenine nucleotides to 50-60% of control values with only a modest (0.95-0.91) reduction in energy charge [ATP + 1/2 ADP)/(ATP + ADP + AMP]. Peroxide-treated myocytes selectively release inosine and adenosine, as only these two purine degradation products were detected in the incubation medium. The most dramatic response was a peroxide dose-dependent inhibition of PDH activity in cultured myocytes as well as freshly isolated mitochondria; just 65 and 30 nmol peroxide/mg protein induced a 50% reduction in cellular and mitochondrial PDH activity, respectively. In conclusion, physiological quantities of peroxide potently inhibit PDH in cultured cardiomyocytes and isolated cardiac mitochondria. PDH inhibition blocks the aerobic oxidation of glucose and inhibits the oxidative phosphorylation of ADP, which in turn leads to cellular adenine nucleotide degradation.

Adenine Nucleotides↗
PubMed1991

[The Pulsair manual noncontact tonometer].

The authors present a report on their own experience with a manual contact-free tonometer Pulsair of Keeler Co. Ais compared with results obtained by means of the manual aplanation Perkins tonometer of Clement Clarke International Ltd. in the group of patients with IOP under 2,8 kPa the arithmetic means of four readings, the scatter of mean values and standard deviations assessed by both methods were not significant. Correlation coefficient 0.92 (p less than 0.001). In the group of patients with glaucoma and hypertonics with IOP of 2.93 kPa and more the arithmetic means of four readings were significantly higher (at the 1% level) in contact-free tonometry. Correlation coefficient 0.95 (p less than 0.001). The authors emphasize the main advantage of the contact-free manual tonometer: safety, rapid procedure, objectivity, accuracy, manual use.

Humans↗
PubMed1991

[Visual function requirements in modern aviation].

The authors describe aviation ophthalmology as a typical ergoophthalmic discipline as regards the sphere of interest as well as with regard to its preventive trend. The visual analyzer is a very exposed sense which can be modified by some dynamic effects of flight to such an extent that they may restrict the pilot's activities and consequently also the safety of the flight. Specific factors of flight which comprise also aerogenic hypoxia, hypobarism, overloading, vibrations and the consequences of impaired relations of the different senses may be manifested by changes of the perception of light, colour, visual acuity, perception of contrasts of the visual field etc. The most modern aviation technique puts some so far unusual demands on vision tested by means of complicated psychophysiological tests. Only the future will show which tests should be included among routine methods of aviation ophthalmology and which tests will be restricted only to experimental work.

Aerospace Medicine↗
PubMed1990

Importance of spontaneous alpha-ketoacid decarboxylation in experiments involving peroxide.

The potential role of spontaneous alpha-ketoacid decarboxylation as a source of interference in experiments involving peroxide was investigated. The assay of pyruvate dehydrogenase activity in isolated renal mitochondria was employed as an example. Spontaneous peroxide-induced pyruvate decarboxylation competed significantly with enzymatic decarboxylation at peroxide concentrations greater than 50 microM. Corrected values for enzymatic decarboxylation could be obtained by subtracting spontaneous decarboxylation rates from rates obtained in the presence of mitochondria. At higher peroxide concentrations (greater than 200 microM), reaction product accumulates (acetoacetate) to levels which may have regulatory effects on mitochondrial metabolism. The divalent cations, Ca2+ and Mg2+, both accelerate spontaneous peroxide-induced pyruvate decarboxylation while other components of the assay medium had an inhibitory effect on the reaction. The results are discussed in relation to the currently accepted reaction mechanism. Investigators who perform experiments involving reactive oxygen species should be familiar with this often overlooked reaction.

Animals↗
PubMed1990

Effect of peroxide, sodium, and calcium on brain mitochondrial respiration in vitro: potential role in cerebral ischemia and reperfusion.

Mitochondrial pyruvate-supported respiration was studied in vitro under conditions known to exist following ischemia, i.e., elevated extramitochondrial Ca2+, Na+, and peroxide. Ca2+ alone (7-10 nmol/mg) decreased state 3 and increased state 4 respiration to 81 and 141% of control values, respectively. Sodium (15 mM) and/or tert-butyl hydroperoxide (tBOOH; up to 2,000 nmol/mg protein) alone had no effect on respiration; however, Na+ or tBOOH in combination with Ca2+ dramatically altered respiration. Respiratory inhibition induced by Ca2+ and tBOOH does not involve pyruvate dehydrogenase (PDH) inhibition since PDH flux increased linearly with tBOOH concentration (R = 0.96). Calcium potentiated tBOOH-induced mitochondrial NAD(P)H oxidation and shifted the redox state of cytochrome b from 67 to 47% reduced. Calcium (5.5 nmol/mg) plus Na+ (15 mM) decreased state 3 and increased state 4 respiratory rates to 55 and 202% of control values, respectively. Sodium- as well as tBOOH-induced state 3 inhibition required mitochondrial Ca2+ uptake because ruthenium red addition before Ca2+ addition negated the effect. The increase in state 4 respiration involved Ca2+ cycling since ruthenium red immediately returned state 4 rates back to control values. The mechanisms for the observed Ca2(+)-, Na(+)-, and tBOOH-induced alterations in pyruvate-supported respiration in vitro are discussed and a multifactorial etiology for mitochondrial respiratory dysfunction following cerebral ischemia in vivo is proposed.

Animals↗
PubMed1990

[Color vision in glaucoma].

The author presents an account on the results of examinations of colour vision in patients with ocular hypertension and open angle glaucoma using three tests according to Farnsworth-Munsell (100 Hue test, Roth's 28 Hue test, Lanthony's desaturated panel D-15). He proves significant deterioration of colour differentiation in groups of patients with glaucoma and ocular hypertension as compared with a reference group and within the group. Although there is deterioration of colour differentiation in the entire spectrum, disorders in the blue-yellow and blue-green area predominate.

Adult↗
PubMed1979

Polyamines: an unrecognised cardiovascular risk factor in chronic dialysis?

The significance of raised polyamine (P.A.) levels in chronic-dialysis patients is unknown. Since these biologically active substances have hormone-like properties and promote cell-growth in plant and animal tissues, it is possible that they stimulate proliferation of arterial smooth-muscle cells (S.M.C.)--a central process in atherogenesis--and thereby contribute to the rapidly accelerated cardiovascular disease observed during dialysis. Such a role for P.A. is supported by tissue-culture studies, which show not only that P.A.-rich serum from dialysis patients stimulates S.M.C. growth, but also that this mitogenic effect is lost when P.A. are selectively removed from uraemic serum and restored by their addition. Although these observations provide new insights into possible mechanisms of atherogenesis, they are not surprising in view of the many known biological actions of P.A.

Arteries↗
PubMed1979

Purification of rabbit antispermine antiserum by affinity chromatography.

Immunoglobulins G were isolated from a crude rabbit antispermine antiserum using a protein A-Sepharose CL-4B column. Affinity chromatography coupling spermine to the Sepharose matrix was employed for separation of antispermine antibodies from these immunoglobulins. Four fractions of antispermine antibodies were isolated by stepwise elution with solutions at pH range from 4 to 1. Binding constants were determined and cross-reactivity with other polyamines was tested for each fraction of antibodies. Highly specific antispermine antibodies were found in fraction IV.

Animals↗
PubMed1978

1-N-Acetylspermidine: occurrence in normal human serum.

Using gas chromatography mass spectrometry following derivatization (N-trifluoroacetylation), 1-N-acetylspermidine was found to occur in normal human serum at a level of approximately 0.008--0.5 nmol ml(-1), i.e. about two orders of magnitude lower than the corresponding spermidine level. No evidence for the occurrence in serum of the isomeric 8-N-acetylspermidine was found. Mass spectra of authentic samples of trifluoroactylated 1-N- and 8-N-acetylspermidine are presented.

Acetylation↗
PubMed1978

Radioimmunoassay of spermidine in human serum.

Specific antispermidine antibodies were produced following immunization of New Zealand white rabbits with a spermidine-thyroglobulin conjugate of high (greater than 200:1) hapten-carrier molar ratio. The harvested antispermidine rabbit antiserum was characterized and a radioimmunoassay procedure developed. The specificity of this antibody was tested against cadaverine, putrescine, spermine, monoacetylputrescine, N-8-acetylspermidine and other compounds of similar molecular structure. Negligible cross-reactivity was observed with putrescine (2.1%), cadaverine (0.6%), spermine (0.3%), diaminopropane (less than 0.1%), and no cross-reaction was found with monoacetylputrescine, N-8-acetylspermidine, histamine, L-lysine and L-ornithine. The spermidine values on serum of five healthy volunteers were determined by RIA and compared with values by gas chromatographymass spectrometry. Statistical evaluation of the results were highly agreeable. Antibody titer, intra-assay precision and analytical accuracy were tested. The assay requires only 20 microliter of serum and has picomole sensitivity. The sensitivity, specificity and small sample requirement make this procedure an effective tool for spermidine analysis.

Animals↗
PubMed1978

Stereospecific antibodies to methadone. II. Synthesis of d- and 1-methadone antigens.

Diastereomeric methadols were prepared by reduction of the methadone enantiomers. Resulting methadols, after purification and characterization by mass spectrometry, were succinylated. The hemisuccinyl derivatives were conjugated with thyroglobulin via carbodiimide condensation. The conjugates of d- and of 1-methadol hemisuccinyl-thyroglobulin were employed as the antigens for immunization of white New Zealand rabbits in order to obtain specific anti d- and anti 1-methadone antisera.

Animals↗
PubMed1977

Stereospecific antibodies to methadone. I. Radioimmunoassay of d,l-methadone in human serum.

Anti-d,l-methadone antibodies were produced in rabbits immunized with d,l-methadol-hemisuccinate thyroglobulin conjugate. Using the antiserum, a radioimmunoasay (RIA) for determination of d,l-methadone in human serum has been developed and is described. Concentration of d,l-methadone of 1.4 pmol in a native serum sample (volume 0.1 ml or less) could be measured directly by RIA. The antibodies crossreact 100% with d,l-methadone, 50% with d-methadone, 50% with l-methadone and 100% with alpha-d-methadol. No crossreactivity was found with alpha 1-methadol, morphine, meperidine, dextropropoxyphene, 2-ethyl-5-methyl-3,3-diphenyl-l-pyrroline and 2-ethylidene-l, 5-dimethyl-3,3-diphenylpyrrolidene. High sensitivity and small sample requirements make this method suitable for future monitoring of patients on methadone maintenance and for studies where other procedures have lack of sensitivity.

Animals↗
PubMed1975

Normal functions of the thyroid gland of the pygmy goat.

Normal values were obtained for blood serum PBI, T3 index. T4, and cholesterol in a colony of pygmy goats (n equal to 55) of mixed sex and age. Serum PBI values averaged 8.1 plus or minus 1.2 mug/dl with no significant sex differences. The mean T3 index and T4 value were 1.1 plus or minus 0.1 and 7.2 plus or minus 1.1 mug/dl, respectively, with no sex differences. The mean serum cholesterol value was 90.0 mg/dl, with sex differences apparent. Serum cholesterol averaged 84.9 mg/dl (n equal to 44) for females and was significantly higher in intact males (97.4 mg/dl; n=8) and significantly lower in castrate males 69.2; n=6. There was a consistent and significant increase in cholesterol values with age in females, an unexplained phenomenon also observed in humans. There was no evidence of thyroid malfunction in the animals studied.

Age Factors↗
PubMed1975

Direct determination of polyamines in human serum by radioimmunoassay.

Antipolyamine antibodies were produced following immunization of New Zealand white rabbits with thyroglobulin spermine conjugate, using multiple-site injection and macrophage-harvesting techniques. The antispermine antibody in a radioimmunoassay system cross-reacted with spermidine (22%), putrescine (1%), diaminopropane (6%), and cadaverine (0.16%). No reaction with L-lysine, ornithine, or histamine was noted. Using this antibody, the radioimmunoassay for direct determination of serum polyamines was developed. A sensitivity of 200 pg was achieved on human serum samples. This radioimmunoassay would appear to be a useful tool for the detection and monitoring of a variety of pathophysiological states associated with abnormal polyamine metabolism, i.e., cancer.

Animals↗