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Biomedical subjects

J Cervenka

Publications and source records attributed to J Cervenka.

At least 73 records · Page 4Linked to original sources
PubMed1982

Temporal parameters involved in retention of reflex alterations in spinal rats.

Temporal parameters concerning retention of a stimulation-induced hindlimb flexion were investigated. After spinal transection, 60 rats received 10, 20, 30, 40, 45, or 50 min of hindlimb stimulation. Consistent persistence of flexion following stimulus cessation was observed in rats that were stimulated for at least 30 min. When the results ae compared with previous data, the spinalized rat shows a 10-min reduction in the critical time interval needed to consistently obtain poststimulation persistence of flexion.

Animals↗
PubMed1982

Prevention of health damage caused by agrochemical substances.

Present paper refers to prevention of health damage caused by agrochemical substances in Czechoslovakia. Authors introduce criteria for the approval of agrochemicals in agriculture [altogether a list of 526 pesticides in 1981]. In socialist countries uniform maximum permissible levels of pesticides in foodstuffs and uniform analytical methods are being established. The necessity of epidemiological studies and that of monitoring pesticide residues in the environment are stressed. During 1973-78 altogether 80 cases of occupational poisoning by pesticides were notified in Slovakia; out of them 45 being severe and 3 lethal ones. Emphasis is given to the need of systematic checking of the use of pesticides in agriculture from the health prevention point of view.

Agricultural Workers' Diseases↗
PubMed1982

Patterns of DNA replication of human chromosomes. II. Replication map and replication model.

Combining higher resolution chromosome analysis and bromodeoxyuridine (BrdU) incorporation, our study demonstrates that: (1) Human chromosomes synthesize DNA in a segmental but highly coordinated fashion. Each chromosome replicates according to its innate pattern of chromosome structure (banding). (2) R-positive bands are demonstrated as the initiation sites of DNA synthesis in all human chromosomes, including late-replicating chromosomes such as the LX and Y. (3) Replication is clearly biphasic in the sense that late-replicating elements, such as G-bands, the Yh, C-bands, and the entire LX, initiate replication after it has been completed in the autosomal R-bands (euchromatin) with minimal or no overlap. The chronological priority of R-band replication followed by G-bands is also retained in the facultative heterochromatin or late-replicating X chromosome (LX). Therefore, the inclusion of G-bands as a truly late-replicating chromatin type or G(Q)-heterochromatin is suggested. (4) Lateral asymmetry (LA) in the Y chromosome can be detected after less than half-cycle in 5-bromodeoxyuridine (BrdUrd), and the presence of at least two regions of LA in this chromosome is confirmed. (5) Finally, the replicational map of human chromosomes is presented, and a model of replication chronology is suggested. Based on this model, a system of nomenclature is proposed to place individual mitoses (or chromosomes) within S-phase, according to their pattern of replication banding. Potential applications of this methodology in clinical and theoretical cytogenetics are suggested.

Bromodeoxyuridine↗
PubMed1982

Synthesis of unsaturated carnitine esters with N-acyl imidazoles.

A novel procedure is described for the synthesis of acylcarnitines. This entails the synthesis of an N-acyl imidazole intermediate, which subsequently is reacted with L-carnitine perchlorate to form the acylcarnitine. The procedure is rapid and simple, and does not require a large excess of N-acyl imidazole to achieve a reaction yield of 50-70%. A procedure, based on reverse-phase Sep-Pak cartridges for rapid isolation of acylcarnitines from these reaction mixtures is also described. These procedures have, in particular, been applied in the synthesis of polyunsaturated acylcarnitines, including docosahexaenoylcarnitine.

Acylation↗
PubMed1981

Fixation of spinal reflexes in rats by central and peripheral sensory input.

Two methods were used to demonstrate retention of postural asymmetries after spinal cord section in adult rats. In the first preparation, postural asymmetries of the hindlimbs were induced by placing electrolytic lesions in the anterior cerebellum. Asymmetry was found to consistently outlast a spinal cord section if 45 min were allowed between brain lesion and cord section. A certain percentage of rats allowed 35 or 40 min also demonstrated the retention. In the second preparation, postural asymmetries induced by 45 min of direct hindlimb stimulation were also retained after spinal section. Rhizotomy prior to stimulation resulted in a lack of appreciable asymmetry upon termination of the stimulation. Finally, retention of a hindlimb-stimulation-induced asymmetry was observed in animals that underwent a spinal section prior to the stimulation. The present series of studies demonstrates that the "spinal fixation" phenomenon can be obtained by induction of postural alterations from central (cerebellar lesion) and peripheral (hindlimb stimulation) sources. In addition, results obtained from spinal animals indicate that retention of peripherally induced asymmetry is not crucially dependent on higher brain center activity but rather seems to be more dependent on long-term alterations that occur directly in the spinal reflex system.

Animals↗
PubMed1981

Karyotype analysis and quantitation of viral transforming genes in Rous sarcoma virus transformed, revertant, and retransformed field vole cells.

Comparative studies of the number of cellular chromosomes and viral genes, including the gene required for malignant transformation, were performed on several clones of Rous sarcoma virus-transformed, revertant, and spontaneously retransformed field vole cells. The results of these studies indicate that no appreciable differences in either total viral gene equivalents or transforming gene sequences can be detected between transformed and revertant cell types, even though considerable differences in the number of certain chromosomes exist among the clones tested. Furthermore, no increase in the amount of total genes or transforming gene sequences accompanies retransformation of revertant clones, including clones that exhibited significant increases in chromosome number following retransformation.

Animals↗
PubMed1981

Delineation of 13q-deletion by replication banding in retinoblastoma.

High-resolution replication banding was performed to (1) delineate at the prometaphase level small interstitial deletions of chromosome 13 in two unrelated patients with retinoblastoma (Rb) and (2) study the influence of these deletions in the replication autonomy of the regions involved. The present study indicates that, in spite of the fact that break points separate (split) bands q14 and q21 in different segments, these deletions do not produce a position effect or alteration in the replication behavior of the abnormal chromosome 13's. Each segment in the deleted chromosomes replicates with a chronology and pattern identical to the normal homolog's. The present data also indicate that metaphase bands are not only autonomous foci of replication but that they can be further divided into subunits of replication which correspond to sub-bands observed in more elongated prometaphase chromosomes. Our results strongly suggest that prometaphase sub-bands represent units of chromatid organization and replication.

Chromosome Banding↗
PubMed1981

Coliphages as ecological indicators of enteroviruses in various water systems.

The occurrence of coliphages and enteroviruses in a variety of water systems in Czechoslovakia was monitored for two years. Two host strains of Escherichia coli bacteria were used to test 1161 water samples for the presence of bacteriophages. These strains were polyvalent hosts for a broad spectrum of morphologically distinct coliphages, and their use thus gave quantitative data on the degree of viral pollution in any given water sample. Ninety-two water samples were tested in parallel for the presence of enteroviruses, by using a flocculation method to concentrate the viruses followed by isolation in cultures of a buffalo green monkey (BGM) kidney continuous cell line. The enterovirus and coliphage recovery rates showed similar differences when waters with different levels of pollution were compared. Seasonal fluctuations of both the coliphage and enterovirus (mostly poliovirus) levels in river water were demonstrated by statistical analysis of the data collected. The levels increased in the winter and sharply declined in the summer months as the river water temperature increased. Chemical pollution did not seem to influence the survival of either the coliphages or the enteroviruses in the observed rivers.

Coliphages↗
PubMed1981

Transduction of amikacin, gentamicin and tobramycin resistance in Pseudomonas aeruginosa with phage F 116 and AP 19, a new wildtype phage.

Amikacin-, tobramycin-, gentamicin- as well as carbenicillin-resistance has been found to be transducible, in various combinations of spectra both with the phage F 116 propagated on an Amikacin-resistant wild-type strain of Pseudomonas aeruginosa (No. BE 11) and with the phage AP 19 isolated from a different Amikacin-resistant strain (No. 578). Both strains were found to transfer Amikacin-resistance genes presumably by conjugation thus possessing an R plasmid coding for multiple antibiotic resistance. Evidence is presented that classical as well as wild-type phages may acquire and transmit antibiotic resistance genes among pseudomonads. This is particularly significant in view of the importance to preserve Amikacin as an effective reserve antibiotic for treatment of poly-resistant infections including those caused by P. aeruginosa.

Amikacin↗
PubMed1981

Mitomycin C test for diagnostic differentiation of idiopathic aplastic anemia and Fanconi anemia.

A cytogenetic test was developed to enable the diagnostic differentiation between Fanconi anemia and the group of disorders classified as "idiopathic" aplastic anemia. The method is based on the effect of the bifunctional alkylating agent mitomycin C (MMC) on chromosomes of peripheral lymphocytes in culture 92 to 96 hours. At the highest concentration of 80 ng/ml of MMC, about a 50-fold increase of chromosomal breaks and a 200-fold increase of radial figures was observed in Fanconi anemia lymphocytes in comparison with the average values for aplastic anemia cells or cells of healthy control subjects. In addition, sister chromatoid exchange analysis of cells treated with MMC demonstrated a marked inhibition of mitotic activity of lymphocytes of patients with increased sensitivity to MMC. It is advocated that the MMC-stress test should be used in each case of pancytopenia, as part of the therapy planning. The cytoreduction regimens used prior to bone marrow transplantation may produce lethal complications in patients with high clastogenic response to MMC.

Adolescent↗