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Biomedical subjects

J Bartos

Publications and source records attributed to J Bartos.

At least 55 records · Page 3Linked to original sources
PubMed1984

A coagulation pathway on bovine aortic segments leading to generation of Factor Xa and thrombin.

Previous studies have demonstrated the binding of Factors IX and IXa to cultured bovine aortic endothelial cells. The present study examines the interaction of Factors IX, IXa, and Xa with the luminal surface of calf aortas, shown by microscopic examination to have a continuous layer of endothelium. Radioimmunoassay of Factor IX showed that 74 fmol/10(6) cells of Factor IX could be eluted from freshly prepared aortic segments. Binding of 3H-Factors IX and IXa to aortic segments was saturable, and comparable to binding in previous studies using cultured endothelial cells. Preincubation of aortic segments with 3H-Factor IXa and von Willebrand factor (VWF)/Factor VIII, followed by washing and addition of Factor X, resulted in formation of Factor Xa. The addition of prothrombin to these activation mixtures resulted in formation of thrombin. Exogenous phospholipid and Factor V were not required for Factor X and prothrombin activation on the intact native endothelium. Incubation of 125I-Factor Xa with the vessel segments resulted in most of the tracer being complexed with antithrombin III originally present on the aortic segment (3.8 pmol antithrombin III/10(6) cells). The Factor Xa-antithrombin III complex was observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis exclusively in the supernatants. 125I-Factor Xa not complexed with antithrombin III bound specifically to the vessel segment. The time course of binding was biphasic, consisting of an initial more rapid reversible phase followed by a slower irreversible phase. The latter phase correlated with the formation of a covalent complex (Mr, 76,000) between 125I-Factor Xa and a vessel-localized protein presumably distinct from antithrombin III. The activation of prothrombin by vessel-bound Factor Xa was inhibited by anti-bovine Factor V IgG, suggesting that there is interaction of Factor Xa with a Factor V-like molecule provided by the endothelial cell surface. Addition of antibody to antithrombin III prevented formation of Factor Xa-antithrombin III and thrombin-antithrombin III complexes in the supernatant and increased apparent thrombin activity 30-50-fold. These studies demonstrate that freshly obtained vessels with a continuous layer of native endothelium can support activation of Factor X and prothrombin: vessel-bound Factor IXa can activate Factor X in the presence of VWF/Factor VIII. Factor Xa can also bind to the vessel and participate in the activation of prothrombin. The apparent efficiency of prothrombin activation, however, is dampened by the presence of functional antithrombin III on the vessel wall.

Animals↗
PubMed1983

[Study of the presence of sterigmatocystin in Czechoslovak grain].

Owing to its carcinogenic, hepatotoxic, nephrotoxic and dermatotoxic action, sterigmatocystine belongs to risky substances. Grains should be therefore examined for its content. A detailed description of a simple method for a current examination of grains for sterigmatocystine content is given and the method is recommended. Seventy-four samples were examined (24 samples of wheat, 19 samples of barley, 16 samples of maize, 10 samples of oats and 5 samples of rye) coming from the South Moravian, West Slovakian and East Slovakian regions from the 1980 and 1981 harvests. Only two barley samples and two maize samples were found to be positive: the maize samples contained about 50 micrograms and the samples of barley 200 and 400 micrograms of sterigmatocystine per 1 kg. One sample of wheat had a trace amount of the substance.

Czechoslovakia↗
PubMed1982

[Detection of T-2 toxin in grains using thin layer chromatography with silica gel (TLC)].

The TLC method of the detection of T-2 toxin in grains is described. A thin layer of silica gel with a sensitivity of 3 mg/kg is used in this method. In comparison with the biological assay for dermal irritability, the TLC method is 30 times less sensitive. However, it has one great advantage over the bioassay: its specificity. It is recommended for practice to use a screening method based on the test for the dermal irritability of rabbits. When the content of toxins is higher, the analytic method can be used for trying to identify the given mycotoxin of the trichothecene group. T-2 toxin was detected in none of the 33 samples of tested grains (14 samples of barley, 7 wheat, 5 rye, 5 oats, 2 samples of maize).

Chromatography, Thin Layer↗
PubMed1982

[Biological assay for trichothecenes in grain].

Three different extract preparation procedures were used to produce the extracts to be applied to the skin of rabbits. In this way one hundred samples of the grains (wheat - 35, barley - 31, maize - 10, rye - 10, oats - 14) originating from the South Moravian, West Slovakian and East Slovakian regions were tested. These samples were taken from the 1980 crop which grew under climatic conditions extremely suitable for the growth of fusaria and the production of mycotoxins. Out of one hundred tested samples only five (5%) had a toxic effect on the rabbit skin. Out of these five samples only three (3%) contained T-2 toxin at the amount of 1 mg . kg-1 (two barley samples) and 0.1 mg . kg-1 (one barley sample) when examined semiquantitatively. The dermal changes evoked by two other samples were caused by other mycotoxins of the trichothecene group because the phenomenon typical of T-2 toxin (stronger skin reaction after 48 hrs than after 24 hrs after application) was not observed. The described method is recommended for screening examination of the grains for the presence of trichothecene mycotoxins.

Animal Feed↗
PubMed1982

[Study of cheeses for the presence of sterigmatocystin].

Sixty-six samples of hard cheeses (Edam Block, Edam Cake, Svĕtlan, Moravian Block, Emmenthal), taken from retail shops, were examined by the chromatographic method using thin silica-gel layer. Three samples were positive. It was demonstrated by semiquantitative examination that two samples of Edam Cake contained 7.5 and 17.5 micrograms of sterigmatocystine in kg and one sample of Moravian Block contained 7.5 micrograms/kg. The described method is very simple and is recommended to be used by food-control institutions for the practical examination of cheese for the presence of sterigmatocystine.

Cheese↗
PubMed1981

[The occurrence of zearalenone in domestic grains].

The occurrence of zearalenone had not been tested n Czechoslovakia; out of a number of analytic procedures for the determination of this mycotoxin in grains and some feed mixtures, the method described by Mirocha et al. (1974) was chosen for this study. The tests were performed with 61 samples of grain and 22 samples of other feeds. In barley 58.3% of the samples were positive in the range from 0.19 to 0.82 micromol.kg-1 in wheat 46.4% of samples in the range from 0.19 to 0.57 micromol. kg-1, in maize 6.7% of samples, containing 0.33 mumol.kg-1. Oat samples contained no zearalenone. The positive findings in the samples of the commercial mixtures COS 1, COS 2, SOL and KPB ranged from 0.19 to 0.32 mumol. kg-1. Zearalenone concentrations above 0.32 mumol. kg-1 were found in seven samples of wheat, in four samples of barley, in one sample of maize and in one sample of complete feed mixture for early-weaned piglets. The described method is recommended for screening examination of grains for zearalenone in Czechoslovakia.

Animal Feed↗
PubMed1981

[Analysis of aflatoxin Ml in fresh milk].

Seventy-seven samples of cow's milk were examined by the method after Stubble-field (1979) for the presence fo aflatoxin M1; 34 of these samples came directly from farms and 43 were mixed, being taken from tank trucks. Aflatoxin M1 was found in five samples from farms and in none of the mixed samples. In the positive cases, concentrations were determined semiquantitatively and were found to range from a trace amount up to 0.38 microgram aflatoxin M1 per litre of milk. Hence the aflatoxin M1 concentration levels never exceeded tha admissible limit value.

Aflatoxin M1↗
PubMed1981

[Foreign substances in the meat and organs of bulls fed on a diet of swine and poultry fecal waste].

The meat and some organs of eight bulls given diet with 5% to 15% supplements of dried pig and poultry excrements for 175 days were subjected to examination for the presence of some foreign substances. The results were compared with samples from eight control bulls, fed the basal diet. Liver was not found to contain any aflatoxins B1 and M1. No statistically significant differences were found in the content of antimicrobial substances. The same can be said of the content of chlorinated pesticides. Residues of organo-phosphorus pesticides were not detected at all. As to chemical elements, the test bulls were found to have a significantly increased content of copper in liver and diaphragm. All the findings of the residues of foreign substances were within limits tolerated by veterinary regulations.

Animal Feed↗
PubMed1980

[Investigation of the presence of aflatoxins B1 and M1 in meat products].

Sixty-four samples of thirty-one kinds of meat products were examined by the chromatographic method with the use of a thin layer of silica gel. No aflatoxin B1 was revealed in any of the samples. Positive findings of aflatoxin M1 were obtained in three products: liver pasty, smoked rolled shoulder, and in the Spis sausage. The values found in semiquantitative evaluation were lower by 2.0 to 2.5 orders than the proposed admissible aflatoxin concentration in foods for adults in the Czech Socialist Republic (5 micrograms kg-1).

Aflatoxins↗
PubMed1980

[The occurrence of foreign substances in food products from animals fed food supplements of animal excrement].

The products of the animal origin (meat, organs, adipose tissue, eggs) from bulls, pigs and poultry which had been given animal excrements as supplements to their feeds (mostly pig excrements, in one case poultry excreta) were studied as to the content of foreign substances. The almost complete absence of aflatoxin and antimicrobial substances, and the determined levels of pesticide residues and chemical elements demonstrated that the studied foreign substances did not accumulate in the tested food as a result of the presence of non-traditional components in the diets of the animals.

Aflatoxins↗
PubMed1980

[Method for the simultaneous determination of aflatoxins B1 and M1 in the liver of slaughter animals].

The method used by Egmond et al. (1979) was chosen from a number of methods recommended for the determination of aflatoxins in raw materials of animal origin. This method is described in detail to facilitate its use in practice in cases of forced slaughters of animals suspected of aflatoxicosis. The sensitivity of the method for aflatoxin B1 and M1 is about 0.05 micrograms . kg-1. On the whole, 88 liver samples were examined for the presence of the aflatoxins B1 and M1. The samples had been obtained from the slaughtered pigs (52), bulls (23), cows (6), calves (5), and from deceased pigs (2). Positive findings were obtained in five of sixteen pork liver samples and in two of the tested five samples of calf liver. All of these animals were suspected of aflatoxicosis. At current slaughter, only one case of 36 examined pigs was found to be positive. Aflatoxin M1 was found more frequently than aflatoxin B1. However, the findings never exceeded the concentration of 100 ng . kg-1; this is less by 1.5 orders than the proposed tolerated concentration for adult animals (5 micrograms . kg-1).

Aflatoxins↗