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K Hruska

Publications and source records attributed to K Hruska.

At least 37 records · Page 2Linked to original sources
PubMed1987

Effect of biological activity of PTH on its peripheral metabolism in the rat.

Previous studies from our laboratory have characterized the peripheral metabolism of parathyroid hormone (PTH) in the dog using radioimmunoassay techniques following injection or infusion of biologically active, bovine PTH preparations. Other investigators have used biologically-inactive labelled PTH and interpreted their results as representative of the normal physiological processes. Since oxidized inactive PTH does not bind to PTH receptors and since we have found substantial differences between the tissue uptake of active and inactive PTH preparations, it is possible that results obtained with inactive PTH preparations may not totally represent the normal metabolism of PTH. Therefore, we performed studies in rats to compare the disappearance of immunoreactive PTH (i-PTH) from plasma following injection of active or inactive syn b-PTH 1-34. The maneuvers of bilateral ureteral ligation and bilateral nephrectomy were utilized to characterize the sites of tissue uptake of i-PTH. The results obtained indicate that inactive syn b-PTH 1-34 has a significantly slower disappearance from plasma than biologically active syn b-PTH 1-34. Reduction of glomerular filtration by acute bilateral ureteral ligation decreased the disappearance of oxidized PTH more than active PTH. Thus, the results indicate a major dependence on glomerular filtration for the removal of inactive syn b-PTH 1-34. The demonstration that the peripheral metabolism of active and inactive syn b-PTH 1-34 is not identical suggests that studies of the metabolism of inactive PTH preparations do not accurately reflect that of biologically active PTH.

Animals↗
PubMed1985

Specificity of the immune response to the oestrone-azo-hapten structure.

Comparison of the cross-reactions between 14 related steroids with eight antibodies showed that each antibody had its individual molecular specificity. During the 183-day period covering eight immunizations, cross-reaction between oestrone and 1-methyloestrone showed only very little change with five antibodies, while the great differences in cross-reactivity values for the individual antibodies were retained. With the same five antibodies, the course of cross-reaction between oestrone and 3-sulphooestrone as well as 6-oxooestrone was also fairly constant, the differences in cross-reactivity in relation to the individual antibodies being considerably large. The blood plasma antibody concentrations measured at the same intervals showed considerable fluctuation, whereas the affinity constants of the respective antibodies, except one of them, showed a moderate upward trend. The suggested molecular parameters of binding sites of the antibodies to the oestrone-4-azo-hapten structure were in surprisingly good agreement with those reported in the literature for mouse myeloma immunoglobulin A proteins possessing dinitrophenyl-binding activity. The individual antibodies exhibited highly sensitive radioimmunoassay curves for both oestrone and 3-sulphooestrone.

Animals↗
PubMed1985

[Dynamics of exogenous progesterone in the blood of pigs stressed with polychlorobiphenyls (PCB)].

For a period of 70 days, young gilts were given rations containing a commercial mixture of polychlorinated biphenyls (PCB), produced in Czechoslovakia (Delor 105). One group of animals (A) was given feed containing 10 mg chlorobiphenyls per kg, the other group (B) was given feed containing 50 mg chlorobiphenyls per kg; on the whole, each animal of group A got 1 g of PCB mixture and each animal of group B 5 g. In about the mid-time of the experiment and before its termination the animals were given an i. m. injection of progesterone; then the animals were studied for the changes in the concentration of blood plasma progesterone. Statistically significant (P less than 0.05) and highly significant (P less than 0.01) differences in the values of the biological half-life of progesterone were found between the group of PCB-treated animals and the control group, and between groups A and B.

Animals↗
PubMed1983

Characterization of antibodies against oestrone-azo-protein conjugates using 3H and 125I radioligands.

This report describes the synthesis of six oestrone-azo-protein immunogens differing in the position of the azo group in the steroid skeleton and in the nature of carrier protein. By nitration of oestrone, 2-nitro- and 4-nitro-isomers were prepared and converted to amino-derivatives by reduction of the nitro group. The diazotized amino-oestrones were coupled to albumin, thyreoglobulin and haemocyanin. The immunogens thus prepared were administered to rabbits to assess the effect of position of the bridge, carrier protein and adjuvant on antibody production and specificity. Very weak immune responses were obtained with both types of albumin immunogen. The presence of the azo group at C-2 position led to a lower antibody production as compared with C-4 derivatives. The relatively high antibody production was achieved by immunization with oestrone-4-azo-thyreoglobulin or oestrone-4-azo-haemocyanin, with the oil component of adjuvant omitted. The antibodies combined with tritiated and iodinated radioligands yielded typical curves showing the sensitivity of 10-20 pg for 3H labelled oestrone and that of 3-10 pg for 125I labelled oestrone. The specificity of the 6 antibodies was tested using 25 related structures. In all these cases there was low cross-reaction with oestradiol, oestriol and their derivatives. On the other hand, the discriminating ability of the antibodies with regard to the opposite end of the molecule, i.e. with regard to the A-ring and partly the B-ring was very low. This makes it possible to use these antibodies for the radioimmunoassay of oestrone alone or some of its metabolites modified in the A-ring. The results of cross reactivity are generalized to the effect that in the oestrone-azo-hapten structure the antigenic determinant area can be ascribed to the size not exceeding 2-3 steroid rings.

Animals↗
PubMed1983

Characteristics of antibodies against 17 beta-oestradiol in homologous and heterologous systems of radioimmunoassay.

Directly iodinated oestradiol-2(4)-iodo-[125I] and oestradiol-6-O-(CMO)-[125I]iodohistamine were prepared and used in conjunction with anti-oestradiol-2(4)-azo and anti-oestradiol-6-O-(CMO) sera for the development of various radioimmunoassay (RIA) systems which showed marked differences in sensitivity and relatively small differences in specificity. Whereas the heterologous combination of oestradiol-6-O-(CMO)-[125I]iodohistamine and anti-oestradiol-2(4)-azo-serum showed a sensitivity expressed in femtograms, the homologous combination using oestradiol-6-O-(CMO)-[125I]iodohistamine radioligand exhibited a sensitivity two orders lower. The specificity of both the heterologous and homologous system did not differ significantly from the RIA system using tritiated radioligand. The combination of directly iodinated oestradiol and anti-oestradiol-2(4)-azo-serum showed a higher sensitivity and a lower specificity as compared with tritiated radioligand.

Antibodies↗
PubMed1983

[The effect of different cell concentrations and incubation time of testicular tissue testosterone synthesis].

The cells of the testes of mice were enzymatically separated and the amount of Leydig cells was determined in different stages of dispersion and after washing the separated tissue. This amount ranged from 2 to 9%. The largest quantity of Leydig cells (9%) was obtained when separated tubuli were washed. The response of cell suspensions at seven concentrations stimulated by human chorion gonadotrophin (HCG) was tested. Cell suspension concentrations from 5.3 x 10(5) to 1.4 x 10(6) cells/ml were found to be satisfactory. After two to three hours of incubation, the values of testosterone could be used for the determination of the activity of gonadotropic preparations.

Animals↗
PubMed1983

[Determination of the activity of luteinizing hormone in PMSG preparations using testosterone synthesis in vitro].

The activity of luteinizing hormone (LH) in serum gonadotropin (PMSG) was studied by a bioassay in vitro, using the cells of mouse testes prepared by the combination of enzymatic and mechanical diffociation. The activity of individual preparations was calculated according to the amount of produced testosterone measured by radioimmunoassay. Comparison with the 2nd international standard of PMSG (WHO) showed that in the PMSG substandard (Dessau) the activity of LH was twice lower, and in three charges of the commercial PMSG preparation (Bioveta, Ivanovice in Haná) four-and-a-half times lower than declared. No great variability of LH activity was observed among the charges of the commercial PMSG preparation.

Animals↗
PubMed1983

Significance of progesterone determination in milk.

The determination of progesterone in milk sampled on the day of insemination is used for fertilization check in dairy cattle. Thus, the corpus luteum function confirms insemination failures due to the false estrus. By this way it is possible to detect 10 to 20 per cent of cows which cannot be successfully inseminated. Further estimation is performed 3 weeks after the insemination when low concentration of progesterone reflects an insemination failure. By this way it is possible to follow up cows inseminated without success and without any clinical symptoms of the next estrus. The repeated estimation of progesterone can objectively monitor the corpus luteum function. This is of great importance for the confirmation of puerperal anestrus, diagnosis of fertility disorders and/or assessment of therapy of sexual cycle disorders.

Animals↗
PubMed1983

Radioimmunoassay of progesterone in cow milk.

Fertilization checks in dairy cattle performed by estimation of progesterone in milk require a simple technique, the use of a sample taken independently of milking procedure and a simple management of the results. The laboratory equipped with a sample processor and pipetting device, high throughput counter for 125iodine and a tabletop computer can analyse about 1000 samples of fat-free milk in one day. The results are used for computer management of reproduction and veterinary service in farms with 600 to 2000 cows.

Animals↗
PubMed1982

[Determination of the gonadotropin activity of biological preparations by testosterone synthesis in mouse testes in vitro].

The ability of mouse testicular tissue to respond to stimulation by a commercial preparation of human choriongonadotropin (Praedyn Spofa) was tested in vitro, using whole testes, fragments and cell suspension. In each experiment seven gonadotropin concentrations ranging from 0.06 to 50 i. u. per litre were tested, and the results were compared with the group of control samples without gonadotropin. The incubation of whole testes with gonadotropin of different concentrations was performed in five vessels, each containing one testis; the fragments were incubated in four vessels, each containing four fragments from different testes, and the cell suspension in triplicates containing 1 . 10(6) cells per ml. All three types of tissue reacted to the increasing concentrations of stimulating agent by the increasing production of testosterone, the concentration of which was determined by radioimmunoassay. For the suppression of the individuality and for achieving a uniform response of the individual samples with each stimulation, the cell suspension of testes from several animals appears to be most suitable.

Animals↗
PubMed1981

[Influencing superovulation in cattle with serum gonadotropin antibody].

The effectiveness of GnRH (Luliberin) and goat anti-PMSG serum prepared at the Veterinary Research Institute, Brno, was studied during the superovulation of heifers treated with PMSG and Estrumate. The use of GnRH did not exert any positive influence on superovulation, as compared with the control groups,. when anti-PMSG serum was administered five hours from the determined beginning of oestrus (46-53 hours from the first administration of Estrumate), the length of oestrus was reduced in comparison with the control group (25.8 and 51.3 h), the number of 22.3). The tested heifers produced 17.8 ova, on an average, out of which (4.1 and 22.3). The tested heifers produced 17.8 ova, on an average, out of which 12.5 were good-quality embryos. The control heifers produced 6.9 ova including 2.9 embryos. The obtained results provide convincing evidence of the promising results of the use of goat anti-PMSG serum during the superovulation cattle.

Animals↗