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Biomedical subjects

J Sikulová

Publications and source records attributed to J Sikulová.

At least 19 recordsLinked to original sources
PubMed1997

Human Escherichia coli O157:H7 infection associated with the consumption of unpasteurized goat's milk.

A cluster of four cases of haemolytic uraemic syndrome in children occurred in Northern Bohemia, Czech Republic, between 15 June and 7 July, 1995. All the cases had significantly elevated titres of anti-O157 lipopolysaccharide (LPS) antibodies as detected by the indirect haemagglutination assay. All but one of them had drunk unpasteurized goat's milk from the same farm within the week before the disease. Evidence of E. coli O157 infection was subsequently found in 5 of 15 regular drinkers of the farm's raw goat's milk; four of them were asymptomatic, 1 had mild diarrhoea at the end of June. Verocytotoxin 2-producing E. coli O157:H7 strains of phage type 2 and of identical pulsed-field gel electrophoresis patterns were isolated from 1 of 2 farm goats and from 1 of the asymptomatic goat's milk drinkers. The frequency of anti-O157 LPS antibodies found among regular drinkers of the farm's raw goat's milk (33%; 5 of 15) was significantly higher than that found in control population (0%; none of 45) (P = 0.0005; Fisher's exact test). Our findings indicate that goats may be a reservoir of E. coli O157:H7 and a source of the infection for humans; raw goat's milk may serve as a vehicle of the pathogen transmission.

Animals↗
PubMed1993

Morphological and functional alterations in endothelium, smooth muscle, and nerve fibers in rabbit aorta after storage at 4 degrees C.

Structural and implied functional changes in endothelial cells (EC), smooth muscle cells (SMC), and nerve fibers (NF) in rabbit aorta were studied after storage in cold Krebs solution. Rings from the thoracic aorta were stored for 2, 4, 6, and 8 days in a refrigerator at 4 degrees C. Subsequently they were examined after 6 h in an organ bath at 37 degrees C and processed for transmission electron microscopy. The earliest and most prominent structural changes were observed in NF and varicosities. These changed after 2 days and were completely destroyed after 6 days. Less remarkable changes in both the intensity and the timeliness of alterations were found in EC. The majority of them showed changes after 4 days. After 8 days they were seriously destroyed, but still formed a relatively continuous layer. The most resistant cells were SMC, showing only slight alterations during the whole period. Contraction of aortic rings in response to transmural nerve stimulation (8 Hz) gradually decreased with the length of cold storage. After 4 days contraction was about 10% of the control value, while after 6 days it was entirely abolished. Maximal relaxation of noradrenaline-precontracted rings in response to acetylcholine was decreased to 46% after 4 days of storage, while after 8 days it was only 15% of the control value. The contractile response of aorta to exogenous noradrenaline did not change during the whole period except for Day 4 when the response was significantly increased. These results showed the different susceptibilities of the EC, the SMC and the NF of the thoracic aorta to cold storage at 4 degrees C (NF > EC > SMC). The observed structural changes were in close agreement with their functional expressions.

Animals↗
PubMed1992

Protection of early cellular damage in 1 Gy-irradiated mice by the elevation of extracellular adenosine.

In whole-body 1Gy-irradiated mice a modification of early cellular damage by means of preirradiation dipyridamole and adenosine monophosphate (AMP) treatment was investigated. Both drugs were given either alone or in combination, AMP being administered i.p. at doses of 5, 10 and 15 mg, dipyridamole s.c. at the dose of 2 mg, 20 min before AMP. The thymidine level in plasma and the amount of free polynucleotides in the thymus and spleen, both estimated at the interval of 4 h after irradiation, were used as indices of early cellular damage in vivo. The elevated level of thymidine observed in the plasma of irradiated controls decreased significantly after the administration of AMP (5 mg) alone to 71%, after the combination of dipyridamole and AMP a still deeper significant fall to 60% was observed. Such a protective effect was observed when injecting AMP 15 min before irradiation. Using the interval of 65 min between AMP administration and irradiation, no protection was detected. The higher doses of AMP (10, 15 mg) enhanced the protective effect manifested in plasma thymidine level only moderately. The amount of free polynucleotides, elevated in the thymus and spleen of irradiated mice, was significantly decreased in the thymus of mice pretreated with the combination of dipyridamole and AMP. The results suggest that the treatment used decreases the radiation damage of the sensitive thymocyte population. It is proposed that the joint use of AMP, an adenosine prodrug, and dipyridamole, a drug inhibiting adenosine uptake by cells, leads to an elevation in extracellular adenosine which activates cell surface adenosine receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1991

The effect of cyclophosphamide and gamma irradiation on adenosine deaminase and purine nucleoside phosphorylase in mice.

Changes in ADA and PNP activities in the spleens and thymuses of mice were studied after a single administration of cyclophosphamide (CY, 200 mg/kg) and after whole-body gamma irradiation (5.5 Gy), applied alone or three days after CY application. In the first days after the treatment the enzyme activities were significantly depressed (p less than 0.01) with the exception of ADA in the spleen, where a high elevation (220-380%) in relation to controls was observed. During the regeneration period a pronounced rise of PNP activity in the spleen occurred mainly after a combined application of CY and irradiation (270%). In the thymus the regeneration was manifested by a mild increase of both ADA and PNP activities towards control values. The findings suggest that the expressive changes of ADA and PNP activities, participating in the purine salvage pathway, may, after a cytotoxic treatment, influence the nucleotide pool and DNA synthesis in lymphoid organs.

Adenosine Deaminase↗
PubMed1989

Purine metabolizing enzyme activities in radiosensitive tissues of mice after sublethal whole-body irradiation.

The activities of adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) were determined between days 1-14 in the spleen, thymus and femoral bone marrow of mice subjected to whole-body gama irradiation with a dose of 5.5 Gy. In control animals, the highest activity of ADA (as related to 10(6) cells) was recorded in the thymus (58.9 pmol.s-1), the lowest one in the femur (34.8 pmol.s-1), the PNP activity was the lowest in the thymus (14.5 pmol.s-1) and the highest in the femur (96.0 pmol.s-1). In the spleen, an elevation of ADA activity (up to 379%) was observed during the first postirradiation days; PNP activity was reduced (to 58%) on postirradiation day 3, followed by the return and even elevation on day 14 (265%). In the thymus, a parallel reduction of the activities of both enzymes appeared during the first postirradiation days, with a subsequent increase during the regeneration phase. In the femoral bone marrow, ADA and PNP activities were increased on postirradiation day 1 (275% and 201%, respectively). Reference is made to the possible relationship between the observed characteristic changes in activities and the degree of damage and/or renewal of cell population in the hemopoietic tissues after irradiation.

Adenosine Deaminase↗
PubMed1984

Protective efficacy of combined administration of lipopolysaccharide of E. coli and chemical radioprotectors under conditions of prolonged irradiation.

We investigated the protective effectiveness of the lipopolysaccharide of E. coli (LPS) in a combination with a mixture of chemical radioprotectors in female mice of the strain H at various radiation dose rates. LPS in a dose of 0.08 mg per kg of body mass was administered 1, 3, or 24 hours prior to irradiation, the radioprotective mixture (cystamine 90 mg X kg-1 + 5-methoxytryptamine 15 mg X kg-1) was administered 10 minutes before irradiation. Dose rates of 612 mGy X min-1 (irradiation time 10 to 15 minutes), 38 mGy X min-1 (3 to 4 hours), and 8.2 mGy X min-1 (27 to 29 hours) were used. The results showed that isolated administrations of LPS or of the radioprotective mixture increased the resistance of the mice against prolonged irradiation; the combined administration even enhanced the efficacy of the radioprotective action. However, this efficacy depended on the magnitude of the dose rate. At dose rates higher than 38 mGy X min-1 the effectiveness of the chemical protection prevailed, whereas at lower dose rates the biological and especially the combined protection became effective. We demonstrated a slight pyrogenic effect of LPS by measuring oxygen consumption and changes in some parameters of the hematopoiesis.

5-Methoxytryptamine↗
PubMed1982

Radiation resistance in mice increased following chronic application of Li2CO3.

In experiments on strain H mice the increased radiation resistance of mice was analysed after three weeks' feeding with a diet including Li given as lithium carbonicum. The concentration of Li in the serum during the first three days of feeding was increased to 0.5 mmol/l and remained at that level to the end of feeding. The application of Li increased the overall number of stem cells in the spleen by 80 per cent compared with the control group. D0 of the line of dependence of the number of endogenous colonies on radiation dose increased following Li application by 1.2 Gy compared with controls. The proliferation activity of haemopoietic stem cells observed 90 min after injection of hydroxyurea was, after 21 days feeding with a mixture containing Li, increased by 200 per cent. The results support the idea that the increased radiation resistance of mice following feeding with Li salts before irradiation may be due to the increased content and resistance of the haemopoietic stem cells, as well as activation of granulopoiesis.

Animals↗
PubMed1978

Protective effect of a mixture of radioprotective substances (AET and mexamine) on the haemopoietic stem cells of mice.

A protective effect of a combined application of radioprotectors (AET -i.p., mexamine -s.c.) was studied in experiments on mice. Duration of the protective effect on the haemopoietic stem cells and on the survival of mice after a lethal exposure to X-ray radiation lasted for 5 hours after the injection. DRF calculated from a change of LD 50/30 reached the maximum (1.53) within 30 min after the injection, and was equal to 1.17 within an interval of 5 hrs. The protection of haemopoiesis, as expressed by DRF calculated from an equieffective exposure for 2 ESC, reached the maximum within a 60 min interval after the injection (DRF=3.4). D0 calculated from the CFU survival curves of endogenous haemopoietic tissue colonies (ESC) was, within a 120 min interval, almost three times higher (310 R) than in the control group (110 R). After the injection of radioprotectors a greater number of haemopoietic CFU survives at an exposure of 100-400 R than after mere irradiation. The postirradiation decrease in the weight of small intestine was smaller in protected animals than in the controls. The role of a decrease of the radiation damage to the haemopoietic stem cells in the total protective effect of the radioprotectors used is discussed.

Animals↗