Biomedical subjects

J Cáslavský

Publications and source records attributed to J Cáslavský.

6 recordsLinked to original sources

PubMed2005

Synthesis, characterization and optical properties of pi-conjugated systems incorporating closo-dodecaborate clusters: new potential candidates for two-photon absorption processes.

Non-centrosymmetric pi-conjugated systems incorporating closo-dodecaborate clusters, [NC-C6H4-C(H=N(H)-B12H11]-(2), [NC-C6H4-C(H)=C(H)-C(6)H(4)-C(H)=N(H)-B12H11]-(3), and [NC-C6H4-C(H)=C(H)-C6H4-C(H)=C(H)-C6H4-C(H)=N(H)-B12H11]-(4) have been synthesized by reaction of the monoamino derivative of B12, [B12H11NH3]-(1), with various arylaldehydes, R-C6H4-CHO. These Schiff base-like compounds were fully characterized by multinuclear NMR spectroscopy and mass spectrometry. In order to evaluate these boron rich pi-systems as potential materials for two-photon absorption (TPA) processes, UV linear absorption curves were recorded for 3 and 4, and comparatively studied with those of the boron-free pi-systems NC-C6H4-C(H)=N-CH3(5) and NC-C6H4-C(H)=C(H)-C6H4-C(H)=N-CH3(6). The donor effect of the boron cluster was evidenced by a shift to the lower energy of the absorption band in the spectra of systems incorporating B12. The two photon absorption (TPA) spectrum of compound , obtained by the up-conversion method, shows a resonance at 720 nm with a cross-section sigma(TPA) of 35 x 10(-50) cm(4) s photon(-1) molecule(-1). This value suggests the potential of B12 clusters to be used as new donor groups for the synthesis of non-linear materials.

Journal Article↗

PubMed2003

[Pitfalls in the diagnosis of carcinoids in patients treated with aminosalicylates].

INTRODUCTION: Carcinoid is one of the most common endocrine active tumours of the gastrointestinal tract. 90% of all carcinoids originate from enterochromaffine cells in the GIT. In the literature the relationship of carcinoid of the bowel and IBD is mentioned, in particular Crohn's disease. The screening test used under our conditions is assessment of the excretion of the metabolite serotonin, 5-hydroxyindole acetic acid (HIAA) in urine. The authors wish to draw attention to falsely positive results of 5-HIAA in urine by the HPLC method in patients with CD treated with aminosalicylates (ASA). METHODS: In order to rule out carcinoid in chronically active CD the authors assessed after discontinuing known interfering drugs the excretion of HIAA by the HPLC method in 14 patients. The results were confirmed in laboratories of the Czech Academy of Sciences using mass spectrometry by desorption and ionization with a laser in the presence of matrix (MALDITOF MS), analytical procedures during processing of the specimens were modified according to Coward. In two patients urinary HIAA excretion was assessed on five consecutive days after discontinuation of ASA. RESULTS: The mean values of HIAA excretion by the HPLC method was highly suspicious of interference. Using the MALDI-TOF MS the authors did not detect 5-HIAA in the fraction of the interfering peak. After discontinuation of 5-ASA the interference disappeared after 4 days. By adjustment of the pH of the mobile buffer phase according to Coward the interfering peak was separated from the 5-HIAA peak. HIAA excretion assessed by the HPLC method was not significantly higher in patients after discontinuation of 5-ASA. CONCLUSION: The authors wish to draw attention to the possible development of carcinoid on the background of chronically active CD. Using assessment of urinary HIAA excretion by the HPLC method as a screening test it is essential to discontinue 5-ASA for at least 4 days before collection of urine or modify the analytical procedure when processing the specimen.

Adult↗

PubMed2000

Heme O is present in Paracoccus denitrificans cells and accumulates under anoxic growth.

In spite of the published claims to the contrary, Paracoccus denitrificans was shown to contain a heme derivative, virtually indistinguishable from the Escherichia coli heme O on the basis of the reverse-phase high-performance liquid chromatography and MALDI-TOF mass spectrometry analyses. Aeration of the anoxically grown culture resulted in the disappearance of a significant portion of this compound with concomitant build-up of heme A.

Anaerobiosis↗

PubMed2000

The use of mosses and pine needles to detect persistent organic pollutants at local and regional scales.

Polycyclic aromatic hydrocarbons (PAHs) were analysed in mosses (Hypnum cupressiforme) and pine needles (Pinus sylvestris) collected in the Czech Republic between 1988-94 at a regional background site in Kosetice, south Bohemia (1988-94) and two industrial sources. One industrial site (sampled 1989-91) in middle Moravia, was near a factory producing PAHs, carbon black and phthalates, the other (sampled 1991-93) near a coal and gas fuel production plant in western Bohemia. Selected chlorinated pesticides and polychlorinated biphenyl congeners were also analysed in samples at the regional background site. This study clearly shows that vegetation sampling can be used to show spatial differences in the atmospheric burden of a range of persistent organic pollutants with differences in the mixtures of compounds reflecting differences in their regional or local use/atmospheric emission.

Journal Article↗

PubMed1997

Drosophila melanogaster, Vicia faba and Arabidopsis thaliana short-term bioassays in genotoxicity evaluation of air and soil samples from sites surrounding two industrial factories in the Czech Republic.

The Somatic Mutation and Recombination Test (SMART) in wing cells of Drosophila melanogaster, the Vicia faba cytogenetic tests-Sister Chromatid Exchange (SCE) and Micronucleus Test (MN), and the Müller test for gametic mutations in Arabidopsis thaliana were used for genotoxicity testing of environmental samples of pollutants from the surroundings of LACHEMA chemical factory (Brno, Czech Republic) and DEZA factory in Valasské Mezirící (Moravia, Czech Republic). Tested soil and air samples were taken from the near vicinity of both factories. The surroundings of both sites are heavy loaded by exhalation of chemicals from the factories. Chemical analyses of the 16 Polycyclic Aromatic Hydrocarbons (PAHs) according to the United States Environmental Protection Agency (US EPA) list of priority pollutants and heavy metals were performed in both soil and air samples. The Drosophila wing spot test was positive in 70.6% of the tested samples, the Vicia sister chromatid exchange test in 62.5%, and the Arabidopsis Müller test in 58.9%. The micronucleus Vicia faba test was quite insensitive in tested environmental samples. The concordance between SMART and SCE was 62.5%, between SMART and Müller test 76.5%, and between Müller test and SCE 100%. Total concordance of these three tests was 79.7%. Müller test for gametic mutation in Arabidopsis thaliana and cytogenetic SCE test in Vicia faba seem to be quite sensitive and convenient plant bioassays for assessing the mutagenic potential of environmental agents, when compared to the SMART test in Drosophila melanogaster.

Air Pollutants, Occupational↗

PubMed1994

TOCOEN project.

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.

Air Pollutants↗