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Biomedical subjects

L Trefil

Publications and source records attributed to L Trefil.

30 records · Page 2Linked to original sources

[Antioxidative properties of ascorbic acid].

Vitamin C (ascorbic acid) is an important hydrophilic compound with antioxidative effect. In the introduction the authors describe possible consequences of loss of vitamin C synthetic ability in an evolutionary ancestor of Anthropoidea. Metabolism of this vitamin is described briefly along with possibilities of its supplementation and determination in biological fluids. Highest attention is paid to metabolic effects of vitamin C, respectively to changes which can be observed after its deprivation, or after the supplementation with this vitamin. Protective effect of vitamin C against lipoperoxidation, its role in modulation of immunity and tumorigenesis are described. Many effects of vitamin C can be explained by its antioxidative activity. The authors show that under concrete conditions, administration of vitamin C can be accompanied by a prooxidative effect. Since vitamin C works in cooperation with other antioxidants, its administration in diseases which are followed by oxidative stress is move effective when used in combined preparations.

Animals↗

Anticipation of acute stress in isoprenaline-sensitive and - resistant rats: strain and gender differences.

The effect of stress anticipation was studied in two inbred Wistar rat strains with high and low sensitivity to isoprenaline. The animals were exposed to tail-flick and 4-hr water immersion restraint stress on two consecutive days. On the first day stress was applied to one group and the next day to the anticipation group. The changes in adrenal, heart and spleen weights, tail-flick latency, incidence of gastric ulcers, and the antioxidant defense system in the sensorimotor cortex were compared with two non-stressed control groups. Anticipatory stress decreased adrenal weights. The content of thiobarbituric acid reactive substances (TBARS) was increased both in acute and anticipatory stress; superoxide dismutase, glutathione peroxidase, and antioxidative capacity were increased in anticipatory stress only. Stress anticipation decreased the pain threshold in the isoprenaline-sensitive and increased in the isoprenaline-resistant rats and led to more frequent gastric ulcers in the isoprenaline-resistant group. Significant sex differences were observed both in adrenal weights and TBARS content. The relative adrenal weights were negatively correlated with the TBARS content. We suggest that the outcome of anticipatory stress may depend upon the relation between the hormonal and antioxidant functions of the adrenals and that anticipation-induced activation of antioxidant enzymes may ameliorate the acute stress response. Anticipation itself was found to be a stronger stressor than physical acute stress.

Analysis of Variance↗

[Effect of antioxidant therapy on indicators of free radical activity in workers at risk of lead exposure].

The authors administered to 36 workers exposed to lead, for four weeks the preparation Prolong which contains vitamin C, vitamin E, beta-carotene, selenium, zinc and chromium and investigated the effect on indicators of free radicals. A statistically significant increase of the following occurred: superoxide dismutase (p < 0.001), glutathione peroxidase (p < 0.01), an increase of the total antioxidant capacity (p < 0.01) and an increase of uricaemia (p < 0.05). Based on these results the authors consider supplementation with antioxidants indicated in workers exposed to lead.

Adult↗

Trichobilharzia regenti, a pathogen of the avian and mammalian central nervous systems.

The development of nasal avian schistosomes of the genus Trichobilharzia in their final host is poorly known. Therefore, an experimental infection of ducklings (Anas platyrhynchos f. dom.) by T. regenti was performed. The infection resulted in leg paralysis and orientation/balance disorders of birds. The examination of the duck's spinal cord and brain confirmed the presence of developing parasites in pre-patent as well as patent periods. The absence of the worms in other tissues strongly supports our hypothesis that the parasite migrates through the central nervous system (CNS) to its final location in bird nasal mucosa. The injury level is probably dependent on number of parasites as well as yet unknown host factors. The affinity to the CNS seems to be high; also by exposure of experimental animals to low cercarial doses the growing worms in the CNS were found. In addition to the generally accepted view that bird schistosomes may cause cercarial dermatitis of mammals (including man), there is evidence of a partial development of T. regenti in mouse CNS; in certain cases leg paralysis was also recorded. Therefore, the pathogenesis spectrum caused by bird schistosomes in birds/mammals needs to be reconsidered.

Animals↗

[Indicators of oxidative stress in cardiovascular diseases. I. Lipoperoxidation].

The level od malondialdehyde (MDA), thiobarbituric acid reactive substances (TBARS) respectively, in blood is changing very quickly and therefore isoprostanes scam to be better markers of atherogenesis. Oxidized LDL belong to the most important reasons of the origin of foam cells and therefore of atherogenesis. That is why the inhibition of the oxidation of LDL particles should belong to the standard therapy of cardiovascular diseases. The value of antibodies against oxidized LDL is difficult to interpret, because they are multifactor dependent, especially under genetic control. Antibodies against LDL modified by malondialdehyde (MDA-LDL) are increased in smokers and individuals with a rapid atherosclerotic progression. HDL-cholesterol protects LDL through the oxidized lipid exchange. Oxidized HDL formed during this process has then an increased clearance from circulation.

Cardiovascular Diseases↗

[Indicators of oxidative stress in cardiovascular diseases. II. Nitrogenous substances, AGE-substances and antioxidants].

By oxidation of nitrogen oxide nitrites and nitrates are formed which can be considered markers of inflammation. AGE-substances (products of advanced glycation) are formed not only from proteins (e.g. Hb-AGE) but also from lipids (AGE-LDL) and DNA (AGE-DNA) and lead to an increased number of mutations. They are toxic and are deposited in the vascular wall. They cause coagulopathy, stimulate cytokines and inactivate nitrogen oxide and thus prevent relaxation of the vascular wall. Extracellular superoxide dismutase (EC-SOD) has a variant (mutation Arg213Gly with a 4% incidence) which causes deterioration of the cardiac prognosis. Selenium deficiency leads also to an increased frequency of cardiovascular diseases.

Antioxidants↗

[Significance of free radicals in the pathogenesis of rheumatic diseases and possibilities of decreasing their pathogenic effects].

The authors present the result of their work where they provide evidence that in inflammatory and degenerative diseases the break-down on superoxide in inadequate. This oxygen radicals and its metabolites play a significant role in the pathogenesis of these diseases. The authors revealed a severe defect in superoxide degeneration in particular in articular exudates of patients with active synovitis. Administration of the preparation Selzink-Plus of PRO.MED.CS Co. Prague which contains selenium, zinc, beta-cyrotene, vitamin C and E along with antirheumatic treatment improves according to the authors the breakdown of superoxide and its metabolites and improves thus the patient's prognosis. Long-term administration of the preparation seems to produce even better results.

Arthritis↗

[On the contamination of the citric acid fermentation. I. The contamination by representatives of Enterobacteriaceae (author's transl)].

Among the most dangerous bacterial contaminations of the citric acid fermentation is the so-called brown contamination, which is called forth by non pathogenic representatives of Enterobacteriaceae like Escherichia coli, Aerobacter aerogenes, Enterobacter cloacae and Proteus vulgaris, while other bacteria do not produce the mentioned contamination. There is given a comprehensive characterization of the brown contamination. Enterobacteriaceae interrupt the growth of the mycelium of the mold Aspergillus niger and stop the production of citric acid, produce a characteristic repugnant smell and reduce nitrate to nitrite. In a case of weak contamination the phenomena of the brown contamination do not appear, but the yield of citric acid is rather low. The contamination may be transferred successfully within the first 24 hrs. of incubation. The effect of the bacteria is determined by their virulence and some other factors.

Aspergillus niger↗

[On the contamination of the citric acid fermentation. II. Sodium 5-nitrofurylacrylate as an antiseptic against representatives of the Enterobacteriaceae (author's transl)].

In context with the first communication which deals with the characterization of the so-called brown contamination called forth by Enterobacteriaceae in the citric acid fermentation of molasses, the present paper describes the screening of antiseptic substances able to suppress the contamination mentioned without damaging the normal growth of the producing mould Aspergillus niger and its ability of producing citric acid. Among the substances tested the sodium salt of 5-nitrofurylacrylic acid (5-NFA) excelled partly because of its antiseptic effect in relatively small concentrations and partly because the mould tolerates appreciable amounts of this antiseptic. Therefore there may be applied, in the presence of a heavy contamination, relatively high concentrations of the antiseptic without fear of damaging the producing mould. Usually a dose of 10 to 15 mg 5-NFA in 11 of medium was sufficient to suppress the brown contamination.

Acrylates↗

Suppression of adjuvant arthritis in rats with chronic bromocriptine treatment does not prevent associated oxidative stress.

We studied the effect of prolactin (PRL) inhibition by bromocriptine (BRC) in the first phase of adjuvant induced arthritis (AA), up to day 11(BRCl-AA), and in the whole time course of AA, up to day 23 (BRC-AA), on the development of the disease in male Lewis rats. On day 24, arthritic rats showed inhibition of PRL secretion, but not PRL mRNA expression in adenopituitaries. BRC treatment suppressed PRL serum levels and PRL mRNA expression in adenopituitaries. In BRC/-AA group PRL levels and PRLmRNA were at the level of rats with AA. Serum corticosterone (CORT) was stimulated by AA from 16.9+/-5.8 to 59.1+/-8.7 ngml(-1), p<0.05, to the same level in BRC-control (BRC-C) and BRC-AA group and further potentiated in BRCI-AA group (148.2+/-33.1 ngml(-1), p<0.05 vs. group with AA). Hind paw swelling was reduced but not completely inhibited in BRC1-AA group and totally prevented in BRC-AA rats as was the core temperature (36.5+/-0.1 degrees C vs. 37.4+/-.0.1 degrees C in AA rats on day 23, p<0.01). Serum concentration of NO-ZNO-3 rose in rats with AA to 28.7+/-2.5 &mgr;mo1L-1 against. 13.9+/-1.9 &mgr;molL(-1) in controls (p<0.01), remained elevated in BRC-AA group and was potentiated in BRC1-AA group (48.2+/-3.5 &mgr;mol(-1), p<0.01 vs. AA or BRC1-AA group) Thiobarbituric acid reactive substances (TBARS) and antioxidant capacity in the spleen were enhanced in rats with AA and to the same extent in BRC-AA or BRC1-AA groups. These results show a discrepancy between the suppression of clinical symptoms and persisting oxidative stress in AA rats after the BRC induced PRL inhibition. The potentiation of nintric oxide (NO-) production after the sudden cessation of PRL inhibition during the disease may promote further joint damage.

Journal Article↗