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Biomedical subjects

J Racek

Publications and source records attributed to J Racek.

At least 73 records · Page 4Linked to original sources
PubMed1996

[Free radial activity in patients with pneumoconioses].

The authors examined indicators of the effect of free radicals (MDA, SOD, GSHPx, selenium) in 20 patients with notified simple silicosis or miner's pneumoconiosis, in 11 patients with complicated silicosis or miner's pneumoconiosis and in 10 patients exposed to fibrogenic dust without an X-ray finding of pneumoconiosis. No statistically significant differences between individual groups were found. Subsequent investigations should be focused on subjects with incipient pneumoconiosis who are not yet entitled to damages.

Aged↗
PubMed1996

[Free radicals in the central nervous system].

Central nervous system has a low antioxidative capacity, which is formed mainly by ascorbic acid. Therefore the cerebral tissue is threatened by the increased formation of free radicals and their metabolites (ROS--reactive oxygen species). ROS are formed such as in reperfusion phase after ischemia and in catecholamine metabolism, in oxidative stress due to hyperglycaemia. Polyunsaturated fatty acids (PUFA) are peroxidased by ROS; proteins and DNK are damaged as well. Free radicals are involved in etiology and pathogenesis of many CNS diseases, such as neuritis, Alzheimer disease, Parkinson disease, Huntington disease, aging and atherosclerosis of the brain, epilepsy, etc. During the antioxidant therapy it is necessary to consider the types of ROS, their origin and their mode of action, whether to administer hydrophilic or lipophilic antioxidants, eventually chelate agents, etc. Hydrophylic antioxidants are acting very soon after the administration, whereas the lipophilic ones reach their target tissues with a great delay. Therefore it is better to apply them preferentially like a prevention, if possible. Enzymatic antioxidants (SOD, GSPHx and catalase and others) are usually acting only for a short time. The methods of estimation of free radicals attacks are discussed as well their possible pathophysiological effects.

Animals↗
PubMed1996

[Free oxygen radicals and rheumatic diseases].

The authors assessed in blood some indicators of the reaction of the organism to the formation and action of free radicals in patients with rheumatoid arthritis, with other inflammatory articular diseases selected at random and with degenerative diseases of the joints and spine. From the results ensues that subjects with inflammations of the synovial membrane respond relatively frequently by a rise of indicators of the antioxidant system such as the activity of superoxide dismutase, glutathione peroxidase or the antioxidant capacity of plasma. Obviously a defence reaction of the organism is involved to the increased formation and action of free oxygen radicals in the inflamed articular lining. The authors conclude that the mentioned laboratory indicators of the action of free radicals could be used when checking the progress of treatment in rheumatic diseases.

Antioxidants↗
PubMed1996

[Determination of free radical activity in workers at risk for styrene exposure].

The authors examined indicators of the effect of free radicals (MDA, SOD, GSHPx, selenium) in 38 workers exposed to styrene. They revealed a statistically significant (p < 0.01) correlation of SOD activity and the period of exposure to styrene and also a statistically significant correlation (p < 0.05) between urinary selenium excretion and the period of exposure to styrene as well as a statistically significant correlation (p < 0.01) between the MDA serum concentration and urinary selenium excretion. There is no statistically significant difference between the MDA plasma concentration among smokers and non-smokers, the SOD activity is significantly higher in non-smokers (p < 0.05). Based on the revealed findings the authors assume that free radicals may also play a part in the action of styrene on the organism.

Adult↗
PubMed1995

[Administration of multivitamin combinations and trace elements in diabetes].

BACKGROUND: Many free radicals are formed in diabetes mellitus due to the oxidative stress in hyperglykemia. The objective of the investigation was to evaluate the influence of an antioxidant mixture and trace elements on some biochemical parameters in controls and diabetic patients. METHODS AND RESULTS: 13 controls (6 men and 7 women, the average age was 53 years) and 9 diabetic patients (4 men and 5 women, the average age was 52 years) were supplemented with multivitamin mixture and trace elements with respect to antioxidant activities. Both groups received the same amount of the mixture, controls 50 days, diabetic patients 35 days. Blood samples were measured before and after the treatment. Renal, liver tests and acid-base balance were not influenced. Apolipoprotein A increased significantly (p < 0.05). Glycosylated hemoglobin in the diabetic group decreased significantly from 9.4 +/- 1.6 to 7.2 +/- 1.5 mumol fructose/g of hemoglobin (p < 0.01). In the diabetic group increased the levels of ionorganic phosphorus from 0.99 +/- 0.08 to 1.15 +/- 0.13 mmol/L (p < 0.01), zinc from 10.4 +/- 1.3 to 14.3 +/- 1.7 mumol/L (p < 0.01), copper from 20.3 +/- 2.3 to 25.9 +/- 6.3 mumol/L (p < 0.05) and selenium in blood from 0.96 +/- 0.21 to 1.65 +/- 0.38 mumol/L (p < 0.001). Selenium in blood of the control group increased from 0.88 +/- 0.26 to 1.66 +/- 0.34 mumol/L (p < 0.001). The activity of superoxide dismutase (SOD) in diabetic group increased from 598 +/- 105 to 696 +/- 103 U/g of hemoglobin (p < 0.01), the activity of glutathion peroxidase (GSHPx) did not change, malondialdehyde (MDA) decreased from 7.1 +/- 1.1 to 5.8 +/- 1.1 mumol/L (p < 0.01) and uric acid decreased from 261 +/- 83 to 236 +/- 96 mumol/L (p < 0.01). CONCLUSIONS: Multivitamin mixture with trace elements significantly protects diabetic patients and the control group against injurous actions of free radicals. That is confirmed by the decrease of plasmatic malondialdehyde and uric acid and by the increase of superoxide dismutase in erythrocytes. The decrease of glycosylated hemoglobin reduces the probability of diabetic complications, the increase of plasmatic Zn and Se in the diabetic group increased the plasmatic antioxidant ability.

Diabetes Mellitus↗
PubMed1995

[Levels of endogenous plasma cortisol in patients with rheumatoid arthritis and other diffuse connective tissue diseases].

The authors tried to obtain information on levels of endogenous plasma cortisol in patients with rheumatoid arthritis and other diffuse connective tissue diseases, in particular systemic lupus erythematosus. Endogenous cortisol was assessed by radioimmunoanalysis at 8 a.m. and 4 p.m. If the sum of the morning and afternoon values reached the level of 280 nmol/l (sum of the lowest still normal values), they considered the daily cortisol secretion still normal. In a group of 30 patients who did not have glucocorticoid therapy the authors found only in one patient a lower daily endogenous cortisol secretion. In 117 patients with a relatively severe course of rheumatoid arthritis where small doses of corticoids (equivalents of 5-10 mg Prednisone) were administered for prolonged periods, a reduced daily secretion of endogenous plasma cortisol was recorded in almost 40%. Repeated examinations made in 13 subjects with rheumatoid arthritis revealed relatively frequent differences in values of endogenous plasma cortisol. In rare instances extremely low plasma levels of endogenous cortisol were found. Similar results as in rheumatoid arthritis, although assessed in a relatively small number of probands, were obtained by the authors also in patients with other diffuse connective tissue diseases, in particular those with systemic lupus erythematosus. Those patients had for prolonged periods roughly double doses of corticoids as compared with patients with rheumatoid arthritis. During repeated examinations the endogenous plasma cortisol levels varied also. The authors are aware that from the assembled results it is so far not possible to draw any definite conclusions and that further investigations are needed which will test the impact of endogenously produced corticoid.

Arthritis, Rheumatoid↗
PubMed1995

[Lipid peroxidation and the antioxidant system in bicarbonate hemodialysis and acetate-free biofiltration].

Acetate-free biofiltration (AFB) is a modern haemodiafiltration method used at present as a variant in treatment of chronic renal failure. In AFB and standard bicarbonate haemodialysis (BHD), performed under equal conditions in 20 patients with chronic renal failure the authors investigated the degree of lipid peroxidation and the antioxidant defence system. As a marker of lipid peroxidation they used malondialdehyde (MDA); as to antioxidant factors they investigated the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSHP) in red blood cells and the selenium (Se) concentration in blood. The MDA values were elevated in both dialyzation methods, as compared with 30 healthy controls (p < 0.001). The SOD value before AFB did not differ from controls, before BHD it was higher than in controls (p < 0.01). In the course of AFB or BHD the SOD values did not change. The GSHPx activity at the end of AFB rose significantly as compared with the initial value (p < 0.05) and the value during the 30th minute of AFB (p < 0.02). In BHD the GSHPx activity was lower than in controls and did not change during the procedure (p < 0.01). The selenium blood levels were before both AFB and comparative BHD lower than in controls (p < 0.001). The authors found a positive correlation between the GSHPx activity and the Se level. The rise of GSHPx activity at the end of AFB may imply improved antioxidant defence during AFB and contribute to reduced tissue damage by free radicals.

Adult↗
PubMed1994

[Rheumatoid arthritis--a diffuse connective tissue disease].

The authors describe in a group of 100 patients, mostly with a severe form of rheumatoid arthritis, subjects with so-called "severe" extraarticular affections which can threaten the patients' lives or cause substantial deterioration of its quality, and those subjects where rheumatoid arthritis was the cause of death. These affections were associated--directly or indirectly--with the basic disease. From the absolute number of revealed affections the authors do not want to draw any conclusions as they are aware of various factors which could influence them. They assume, however, that the assembled data provide evidence that the American Rheumatological Association was right to include rheumatoid arthritis among diffuse connective tissue diseases and that it must be considered not only a disease of the locomotor apparatus but a potential disease of the organism as a whole.

Arthritis, Rheumatoid↗
PubMed1994

[Evaluation of the nutritional status during treatment of anemia using erythropoietin in patients on regular dialysis therapy].

Treatment of anaemia with human recombinant erythropoietin (r-Hu EPO) substantially improves the quality of life of patients receiving regular dialysis treatment. The positive effect on the nutritional state of patients during r-Hu EPO treatment is not accepted unequivocally so far. The authors followed-up 9 patients (6 men and 3 women) who had regular dialysis treatment, and suffered from severe anaemia. The patients were treated for 12 months with r-Hu EPO (preparation Eprex Cilagd Co.) with an initial dose of 30 mu/kg 3x per week by s.c. route with a target haemoglobin (Hb) value of 90-100 g/l. Before treatment during the 6th and 12th month of treatment the basic nutritional parameters of the patients were followed up. In the course of the investigation the Hb level (x +/- SD) increased from 61 +/- 12 g/l to 98 +/- 8 g/l, p < 0.01. On comparison of the nutritional parameters before treatment and after 12 months of treatment with r-Hu EPO the authors recorded rising trends in the patients' body weight (kg) from 67.4 +/- 12.2 to 68.4 +/- 11.2 (n.s.), an increase of the skinfold thickness above the triceps brachii muscle (mm) from 8.6 +/- 5.8 to 9.8 +/- 4.3 (n.s.), a decline of skin reactivity to diphtheric antigen (mm) from 2.1 +/- 2.8 to 1.8 +/- 0.8 (n.s.), a rising trend of reactivity to Candida antigen (mm) from 2.9 +/- 2.2 to 3.9 +/- 2.4 (n.s.), to diphtheric antigen from 3.0 +/- 3.3 to 5.1 +/- 3.8 (n.s.), a rise of the transferrin level (g/l) from 2.5 +/- 0.3 to 2.8 +/- 1.3 (n.s.), a rise of serum urea (mmol/l) from 25.7 +/- 3.6 to 32.5 +/- 9.5 (n.s.), a rise of Mullen's nutritional index from 21.8 +/- 15.5 to 22.3 +/- 24.7 (n.s.).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

A yeast biosensor for glucose determination.

A yeast potentiometric biosensor for glucose determination is described. After induction of glycolytic enzyme synthesis a cell suspension of the yeast Hansenula anomala is retained in calcium alginate gel on the surface of a glass electrode. This biosensor gives a Nernstian response in glucose concentration of 5 x 10(-4)-5 x 10(-3) mol/l with a response time of 5 min and a life-time of at least 2 months. Mannose and fructose are the only significantly interfering substances. The biosensor was used for measurement of glucose concentration in urine with results comparable to those obtained by a photometric enzymatic method.

Biological Assay↗
PubMed1991

What are the factors contributing to the changes in tissue-type plasminogen activator during haemodialysis?

Haemodialysis (HD) is associated with stimulation of the fibrinolytic system. The increase of fibrinolytic activity seems to be primarily due to tissue-type plasminogen activator (t-PA) released from the vessel wall. The aim of our study was to determine whether the t-PA release is the consequence of uraemic intoxication adjustment, extracorporeal circulation effect, heparin administration, or whether a mere reflection of the circadian rhythm of fibrinolysis is involved. To identify the factor, fibrinolytic system parameters were determined during HD, sham HD (SD), after the administration of heparin alone outside HD, and during a control period (CP). The plasma concentrations of t-PA antigen indicate that HD is associated with the release of t-PA from the vessel wall; 3.70 ng/ml before HD, 4.35 (NS) at the 15th min, 4.88 (P less than 0.05) at the 20th min, and 5.09 (P less than 0.05) after HD (medians). The respective values for a CP are 4.05, 4.37 (NS), 4.40 (NS), and 4.22 (NS). The effect of heparin alone and SD was evaluated for 120 min only, with the following t-PA concentrations determined after heparin: 5.10, 6.22 (NS), 4.72 (NS), 4.72 (NS); during SD and 4.50, 5.14 (NS), 5.20 (P less than 0.05). We conclude that t-PA is released from the vessel wall during HD. A factor contributing to its release is the extracorporeal circulation system.

Adult↗
PubMed1987

Biosensor for lactate determination in biological fluids. 2. Interference studies.

The selectivity of a yeast lactate biosensor with immobilized cells of aerobic yeast Hansenula anomala was studied. Reducing substances potentially present in blood plasma influenced both enzyme and yeast biosensors in the same way; the highest positive error was observed in the case of uric acid. With respect to the metabolic activity of the yeast cells the biosensor was absolutely specific for lactate during the first two weeks; later on the biosensor responded slightly to some other metabolites, especially some sugars and amino acids. Glucose could cause the highest degree of interference, its effect was however completely eliminated by adding sodium fluoride to the reaction solution. The concentration of other metabolites present in blood plasma is not great enough to call a significant positive error. The results thus support the general use of the yeast lactate biosensor for lactate determination in biological material.

Humans↗
PubMed1987

Biosensor for lactate determination in biological fluids. I. Construction and properties of the biosensor.

The preparation of a biosensor for lactate determination is described. The biosensor is based on an immobilized suspension of the aerobic yeast Hansenula anomala, containing flavocytochrome b2 in high activity. The conditions for yeast cultivation were optimized to gain a sufficiently high activity of this enzyme converting lactate in the cells. The properties of the biosensor are compared with those of a sensor based on immobilized enzyme flavocytochrome b2. The yeast lactate biosensor has a sufficient sensitivity and linearity and short time of response. The precision and accuracy of lactate determination as well as the results of comparisons using an enzyme electrode and the spectrophotometric UV-test, enables this biosensor to be used in routine work. Analysis can be performed in blood plasma or whole blood. The stability of the biosensor makes it possible to work for 4 weeks with one yeast cell pellet.

Drug Stability↗