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Biomedical subjects

J Vácha

Publications and source records attributed to J Vácha.

At least 19 recordsLinked to original sources
PubMed1990

Ferrokinetics and erythropoiesis in mice after long-term inhalation of benzene.

Ferrokinetics and erythropoiesis were examined in mice exposed for 6 or 7 weeks to an airborne concentration of 300 ppm of benzene, for 6 h per day, and 5 days per week. Ferrokinetic indicators showed only a slightly enhanced production of haeme and erythrocytes in the spleen (133% +/- 18% and 122% +/- 17%, respectively). Production did not change in the femoral marrow; a decline of CFU-C, BFU-E and especially CFU-E (34% +/- 8%) took place there and a shift of cellularity into less mature developmental classes in the erythroblast compartment, without this compartment as a whole being damaged. The erythrocytes produced have an enhanced MCV (109% +/- 0%) and MCH (109% +/- 1%) with an unchanged MCHC; their concentration in blood sank to 87% +/- 1%. The absolute reticulocyte count rose to 160% +/- 16%. 59Fe incorporation into the liver declined far below the level attributable to decreased accessibility of the tracer (84% +/- 4%). A shortening of the life span of late erythroblasts and circulating erythrocytes was deduced from these findings and methodological problems related to some of the seemingly controversial findings are discussed.

Administration, Inhalation↗
PubMed1978

Liver growth, biosynthesis of cytidine nucleotides and level of cytochrome P-450 in rat liver after administration of alpha-hexachlorocyclohexane.

The biosynthesis of cytidine nucleotides and the level of microsomal cytochrome P-450 in intact and regenerating rat liver after repeated administration of alpha-hexachlorocyclohexane (alpha-HCH) were compared. In alpha-HCH treated animals the utilization of [2-14C] orotic acid for the synthesis of cytidine nucleotides is suppressed. In 24-h regenerating liver the incorporation of labelled orotic acid into cytidine nucleotides is markedly activated; the degree of activation is lower in regenerating livers of alpha-HCH treated animals. The changes in the level of cytochrome P-450 vary inversely with the changes in the utilization of [2-14C] orotic acid for the synthesis of cytidine nucleotides. The activity of cytidine triphosphate synthetase of liver cytosol increases shortly after the administration of alpha-HCH; uridine-cytidine kinase is enhanced in the later stages of the drug action. Within 15-45 min after the administration of alpha-HCH the uptake of [U-14 C] cytidine into the liver and its incorporation into RNA cytosine are increased. After the administration of the drug the uptake of [2-14 C] uridine and its incorporation into RNA uracil is also enhanced whereas its utilization for the synthesis of cytidine nucleotides of the acid-soluble extract as well as for the RNA cytosine are suppressed.

Animals↗
PubMed1978

Pyrimidine nucleotide synthesis in rat liver after the administration of cycloheximide.

After the administration of cycloheximide (2 mg/kg) the utilization of [2(-14C)]orotic acid for the synthesis of pyrimidine nucleotides of acid-soluble extracts of the liver is not affected for about 7 h. The specific activities of uridine and cytidine components are increased later on, and this increase is higher in the case of cytidine components. Analogous changes undergoes the specific activity of RNA pyrimidine nucleotides. The increased utilization of labeled orotic acid for the synthesis of cytidine nucleotides can be observed also in the kidney and in the small intestine. The enhanced degree of labeling of cytidine nucleotides in vivo cannot be correlated with the activity of cytidine triphosphate synthetase (EC 6.3.4.2) of liver cytosol estimated in vitro. The amination of UTP is suppressed at later intervals after the application of cycloheximide. The same holds true for the activity of uridine phosphorylase (EC 2.4.2.3),5'-nucleotidase (EC 3.1.3.5) ATPase (EC 3.6.1.3) and of liver cytosol. The activity of uridine kinase (EC 2.7.1.48) is increased when tested both with uridine and cytidine as substrates. Cytidine deaminase activity (EC 3.5.4.5) raises markedly 3--5 h after the administration of drug; later on it decreases again.

Animals↗
PubMed1978

Comparison of life span of erythrocytes in some inbred strains of mouse using 14C-labelled glycine.

The erythrocyte life span in four inbred strains of mice--C57BL/10ScSnPh, B10.LP, BALB/c and CBA/JPh--was determined by means of erythrocyte labelling with 14C-glycine. Experimental data [decrease of 14C-activity of washed erythrocytes], corrected for blood loss, reincorporation of the label and delay in label incorporation during the initial period, were treated by a novel mathematical procedure based on the death probability function of the form: mu [t] = a + btlambda. The mean erythrocyte life span calculated using this function was, in the given sequence of strains, 42.1 +/- 0.6, 41.3 +/- 1.2, 39.3 +/- 0.9 and 38.6 +/- 0.6 days respectively. The rate of "random" destruction of erythrocytes was 1.20, 1.31, 0.70 and 0.63% of the total number of erythrocytes per day and a "mean potential" erthrocyte life span was found to be 58.9, 59.9, 46.2 and 44.5 days respectively. All the given parameters have similar numerical values in related strains and are apparently genetically conditioned. The erythrocyte life span determined simultaneously using DF32P labelling in the C57BL/10ScSnPh strain was 47.4 +/- 1.0 days. The implications of the results yielded by these two techniques is discussed.

Animals↗
PubMed1978

Determination of heme and non-heme iron content of mouse erythropoietic organs.

A procedure is described for determining the content of heme and non-heme iron in organs and tissues of the mouse. Heme iron after homogenization and hemolysis of the samples is extracted as hemin by means of a mixture of ethyl acetate and glacial acetic acid, the extraction being followed by washing with hydrochloric acid. Total iron content is determined with commercial analytical sets exploiting color reaction with bathophenanthroline after mineralization of the samples. The presence of bone or other tissues does not distort the results. The procedure is relatively simple and suitable for serial analyses. The results obtained for the mouse by this method are in good agreement with recognized principles of ferrokinetics in mammals.

Animals↗
PubMed1977

Decreased utilization of [2-14C]orotic acid for the synthesis of cytidine nucleotides in rat liver after administration of alpha-hexachlorocyclohexane.

Administration of alpha-1,2,3,4,5,6-hexachlorocyclohexane (alpha-HCH) to rats decreased the utilization of [2-14C]orotic acid for the synthesis of liver cytidine nucleotides. The specific radioactivities of uridine components of the acid-soluble pool and rRNA increased during the first hours of treatment with the drug. Later on the specific radioactivities of uridine nucleotides remained unchanged, while those of cytidine components decreased gradually. Administration of hydrocortisone increased the incorporation of labelled orotic acid into rRNA cytidylic acid.

Animals↗
PubMed1975

Studies on non-haemoglobin erythrocyte iron; the influence of haemolysis on plasma iron determinations.

Approximately 2% of iron contained in mouse erythrocytes is transferred into supernatant when haemolysed erythrocytes are precipitated with trichloroacetic acid. The component unprecipitable with trichloroacetic acid is probably bound predominantly to reticulocytes and it is larger the younger is the reticulocyte. Under the conditions of postirradiation suppression of erythropoiesis this component grows strongly and in the phase of overrecovery of erythropoiesis decreases. The numerical values determined in the paper can be used for a correction of the disturbing influence of haemolysis on concentration and radioactivity of plasma iron in the resting state of erythropoiesis, if a preliminary precipitation of a sample with trichloroacetic acid was carried out.

Animals↗
PubMed1975

Blood volume in inbred strain BALB/c, CBA/J and C57BL/10 mice determined by means of 59Fe-labelled red cells and 59Fe bound to transferrin.

Circulating red blood cell (RBC) and plasma volume was determined in male inbred strain BALB/c, CBA/J and C57BL/10 mice by parallel use of the 59Fe-labelled RBC dilution and the dilution of 59Fe bound to transferrin. The whole blood volumes values derived from the venous haematocrit and plasma volume were about double the values calculated from the venous haematocrit and circulating RBC volume. Comparison of the two methods thus explains the marked differences in different studies of blood volume in mice and shows that correct values can be obtained only by parallel measurements of RBC and plasma volume by separate methods, or by correcting the venous haematocrit to whole body haematocrit. Combination of the labelled RBC method and the 59Fe-transferrin method showed the blood volume values in the above strains of mice to be 10.35 +/- 0.16, 7.32 +/- 0.10 and 7.94 +/- 0.15 ml/g b.w. respectively. The ratio of whole body to venous haematocrit in these strains was was 57.3 +/- 1.6%, 68.0 +/- 1.8% and 69.5 +/- 2.2%. Significant interstrain differences were demonstrated in RBC, plasma and blood volume and in the venous and whole body haematocrit and their ratio.

Animals↗