Biomedical subjects
Publications and source records attributed to J Petrik.
The basic goals of the TOCOEN project (Toxic Organic COmpounds in the ENvironment) are to detect and understand the fate of selected organic pollutants (PAHs, PCBs and PCDDs/Fs mainly) in the environment. The TOCOEN project was established in 1988 as a free association of Czech and Slovak environmental chemists, ecototoxicologists and other environmentalists.
It was the aim of our study to prove a potential correlation (a) between laboratory findings of cholestasis and autonomic neuropathy (AN) and (b) between the severity of AN and the prolongation of the corrected QT-time (QTc). The five standard tests of autonomic cardiac neuropathy were investigated. QTc was calculated according to Bazett's formula. 12 out of 14 patients with primary biliary cirrhosis, 18 out of 21 patients with HBsAg positive liver diseases and 11 out of 14 patients with cirrhosis of other origin had AN. No significant correlation between the laboratory parameters of cholestasis and AN was found. Abnormal QTc values (> 440 m/sec) were observed significantly more often (p < 0.002) in patients with AN than in patients without AN. Significant linear regression (p < 0.01) could be confirmed between the prolongation of the QTc-time and the severity of AN. Besides the non-invasive investigation of the cardiovascular reflexes the evaluation of the QT-time might be an additional diagnostic means to identify patients with an increased cardiovascular risk in chronic non-alcoholic liver diseases.
Novel phosphate derivatives of the anti-HIV nucleoside analogue AZT have been prepared by phosphorochloridate chemistry. In particular, phosphates carrying ester-containing side-chains are described. These materials are designed to act as membrane-soluble pro-drugs of the bio-active free nucleotides. In vitro evaluation revealed the compounds to have a pronounced, selective antiviral activity. In several cases the phosphate derivatives are more selective in their action than the parent nucleoside AZT. In particular, this arises from the low toxicity of the phosphate pro-drugs by comparison to AZT. These data support the suggestion that the phosphate derivatives exert their biological effects via intracellular release of the nucleotide forms, and suggests that such pro-drug forms may be worthy of further study.
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Mixed infection of MDCK cells with influenza A and influenza B viruses leads to a reduction in the rate of synthesis of haemagglutinin (HA) and nucleoprotein (NP) as compared to their rate of synthesis in cells separately infected with these viruses. The reduction is much stronger for influenza A virus proteins. The synthesis of the nonstructural NS1 protein of both viruses is relatively resistant to the heterotypic interference. The synthesis of virus-specific mRNAs exhibits the same pattern: the formation of the transcripts of HA and NP genes is much more drastically reduced than the synthesis of NS gene transcripts. The effect is strongly dependent on the multiplicity of infection and on the ratio of influenza A and B viruses in the inoculum. Primary transcription in the presence of cycloheximide is almost unchanged in doubly infected cells as compared to single infection, and no indication of differential inhibition has been observed. The results are discussed in connection with the mechanism of heterotypic interference and the regulation of influenza virus protein synthesis.