Biomedical subjects

D Bartos

Publications and source records attributed to D Bartos.

At least 19 recordsLinked to original sources

PubMed1995

Role of reactive O2 in phagocyte-induced hypermetabolism and pulmonary injury.

Activated phagocytes possess an enormous capacity for O2 consumption via NADPH oxidase. NADPH oxidase partially reduces O2, forming superoxide (O2-). Host enzymes rapidly complete O2- reduction to H2O, leaving little trace of its prior existence. Our objectives were to estimate the magnitude of whole body phagocyte respiration and determine the contribution of NADPH-derived O2- to the ensuing phagocyte-induced pulmonary injury. These objectives were accomplished using specific inhibitors of NADPH oxidase, diphenyl iodonium (DPI) and di-2-thienyl iodonium (DTI). Guinea pigs received intravenous injections of DPI (3.5 mg/kg), DTI (7.5 mg/kg), or vehicle followed by phorbol myristate acetate (PMA). Phagocyte activation by PMA immediately increased whole body respiration from 13.6 to 16.1 ml O2.kg-1.min-1 (P < 0.05). DPI and DTI completely blocked the increase in respiration induced by PMA injection (P < 0.05). Baseline respiration was unchanged by the NADPH oxidase inhibitor alone. Likewise, there was no effect on the respiration of isolated heart and kidney mitochondria from animals receiving the inhibitor with or without PMA. DPI attenuated the pulmonary injury induced by PMA. DPI attenuated the pulmonary injury induced by PMA. The ratio of lung water weight to dry weight was lower (6.4 +/- 0.3 vs. 8.3 +/- 0.6) and arterial PO2 was higher (86 +/- 9 vs. 56 +/- 6 Torr) in animals receiving DPI plus PMA than in those receiving PMA alone. In conclusion, phagocyte activation in vivo increased total body respiration by approximately 18%. The burst in respiration is attributed to the phagocyte respiratory burst in which NADPH oxidase partially O2 to O2-.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

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↗

PubMed1989

[Contrast sensitivity in glaucoma].

Author reports on results of the contrast sensitivity examinations using the Cambridge low-contrast lattice test supplied by Clement Clarke International LTD, in patients with open-angle glaucoma and ocular hypertension. In glaucoma patients there was observed statistically significant decrease of the contrast sensitivity. In patients with ocular hypertension decrease of the contrast sensitivity was in patients affected by corresponding changes of the visual field and of the optical disc. The main advantages of the Cambridge low-contrast lattice test were simplicity, rapidity and precision of its performance.

Adult↗

PubMed1988

Chronic hyperdynamic sepsis in the rat: I. Characterization of the animal model.

We describe a new rat model of chronic hyperdynamic sepsis. After control values for weight gain, and food and water intake of each animal were obtained over a 5-day period, male Sprague-Dawley rats weighing 370-425 g were anesthetized, catheterized to allow chronic cardiac-output measurements, and a sterile subcutaneous cavity was formed over the flank area. The animals were allowed a 3-4 day postoperative recovery period. Body weight, food and water intake, and cardiac output were measured daily. Frequent blood samples were withdrawn for bacterial cultures and white cell counts (WBC). On the third and, in some cases, the fourth postoperative day, the subcutaneous cavity was inoculated with 10(9) colony-forming units of Escherichia coli and Bacteroides fragilis. The resulting sepsis was characterized by loss of body weight in spite of normal food and water intake, increased cardiac output, increased WBC, intermittent bacteremia, decreased muscle mass, and decreased cross-sectional area of skeletal muscle myofibrils. Two levels of septic response emerged--moderate and severe. Based on the above-mentioned measurements, it was possible to categorize all long-term septic animals into these two groups. Both groups exhibited cardiac-output, body-weight, and WBC data significantly different from sham controls. Repeated inoculations of the subcutaneous abscess initiated on the third postoperative day resulted in moderate sepsis with no long-term mortality, severe sepsis with 23% mortality over a 3-week period, or a 100% mortality within 4 days, depending on the virulence of the E. coli organisms used. The new model is ideally suited for pathophysiologic studies of sustained, hyperdynamic sepsis.

Animals↗

PubMed1981

Identification of spermine as an inhibitor of erythropoiesis in patients with chronic renal failure.

Fetal mouse liver and normal human bone marrow cell cultures were used for studies on the inhibition of erythroid colony formation (CFU-E) by sera from anemic patients with end-stage renal failure and the polyamine spermine. Sera from each of eight predialysis uremic anemic patients with end-stage renal failure produced a significant (P < 0.001) inhibition of erythroid colony formation in the fetal mouse liver cell cultures when compared to sera from normal human volunteers. In vivo or in vitro dialysis of the uremic sera with a 3,500-dalton exclusion limit membrane removed the inhibitor from uremic sera. The uremic serum dialysate provided by the membrane fractionation was significantly inhibitory in the erythroid cell cultures. When this dialysate was applied to gel filtration chromatography (Bio-Gel P-2) the inhibitor was found to be in the same molecular weight range as [(14)C]spermine. The polyamine spermine produced a dose-related inhibition of erythroid colony formation (CFU-E) in fetal mouse liver and normal human bone marrow cultures. Thus, the following evidence is provided that the in vitro inhibitor of erythropoiesis found in chronic renal failure patients' sera is identical with the polyamine spermine: (a) the inhibitor and radiolabeled spermine appeared in identical Bio-Gel P-2 effluent fractions; (b) when spermine was added to normal human sera at concentrations reported in sera of uremic patients, and studied in both the fetal mouse liver cell culture and normal human bone marrow cultures, a dose-related inhibition of erythroid colony (CFU-E) formation was noted; and (c) the inhibitory effects of crude uremic serum, uremic serum dialysate, and fractions of uremic serum dialysate from a Bio-Gel column, on erythroid colony formation were completely abolished by the addition of a specific rabbit antiserum to spermine.

Animals↗

PubMed1980

Antibody to spermine: a natural biological constituent.

A protein that binds spermine specifically was separated from normal rabbit serum by affinity chromatography. Immunoelectrophoresis, the Ouchterlony immunodiffusion test, and gradient gel electrophoresis indicated that this protein has immunoglobulin characteristics and consists of several populations of antibodies to spermine. These were sequentially released from Sepharose-spermine gel by step-wise elution with solutions ranging in pH from 4 to 1. The binding constants varied from 5.0 x 10(8) to 11.1 x 10(8) liters per mole. These globulins did not react with monoacetylputrescine, L-ornithine, L-lysine, and histamine. Negligible cross-reactivity was detected with spermidine, putrescine, N8-monoacetylspermidine, cadaverine, and diaminopropane. Since perturbations in polyamine metabolism have been identified in several diseases, the study of extracellular polyamine homeostasis may reveal an important regulatory function for this protein.

Animals↗

PubMed1980

Polyamines and polyamine complexes: analytical comments.

Different methods of sample preparation for determination of di- and polyamines (putrescine, spermidine, spermine) and their conjugates in serum, plasma, and urine are discussed. Higher polyamine values obtained after hydrolysis of serum or plasma acidic extracts suggest the presence of polyamine conjugates. Additional polyamines might be bound to proteins and released by hydrolysis of the crude samples. Biological studies of bound polyamines in health and disease will require procedures for quantitative analysis. For the pertinent measurements, radioimmunoassays employing antibodies developed against isolated polyamine conjugates may prove useful.

Acetylation↗

PubMed1980

Development of a specific antispermine antibody.

Highly specific antibody to spermine was produced in the rabbits by immunization with a spermine-thyroglobulin conjugate of high molar ratio (740:1). Cross-reactivity with spermidine was 1.4-2.2 percent and negligible with putrescine and other compounds of similar structure. The average affinity constant of five pools of antispermine rabbit antisera was Ka = 1.8 +/- 0.2 X 10(8) liter/mole.

Animals↗

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↗