No abstract available

No abstract available

[en] Molybdenum excretion in the bile and faeces was studied in Wistar strain rats by ⁹⁹Mo radiometry. After 8 weeks when the experimental animals had ingested 336 mg Cu/kg b.wt. they were administered a dose of 6 mg Mo/kg b.wt. in form of disodium molybdate, disodium molybdate reduced with hydrazine and stabilized with ascorbic acid, or of ammonium tetrathiomolybdate. The total amount of excreted bile was 2.53±0.42 g in 4 hours. The results show that molybdenum excretion is obviously affected by the valency of the administered compound. Pentavalent molybdenum is only excreted in a negligible amount and excretion is not affected by the amount of copper in the diet. Hexavalent molybdenum in association with oxygen is excreted far more intensively but the effect of copper intake is little shown. In the administration of ammonium tetrathiomolybdate, the effect of copper on molybdenum excretion is statistically significant. (J.B.)

[en] The kinetics was studied of the retention and distribution of molybdenum in rat teeth. The chemical form of the molybdenum, the fractions of the molybdenum in the blood and the molybdenum content in the saliva were also investigated. The Wistar-Konarovice rat strain was used for the experiments fed a normal diet with an average content of Mo of 0.34 ppm. Chronically exposed animals were fed distilled water containing 800 ppm Mo in the form of ⁹⁹Mo-labelled sodium molybdate. (B.S.)

[en] Male Wistar rats were treated with Mo in a single dose or over a period of 84 days. The course of molybdenum excretion after a single dose was expressed mathematically. It was shown that various tissues produced different excretion curves and a high retention was observed only in skin. In long-term treatment it was possible to ascribe this retention to direct binding of molybdenum to collagen. In contrast to some other heavy metals molybdenum causes a decrease of collagen stability. The mechanism of this effect is discussed. (author)

[en] Changes of corneal permeability for ²²Na caused by benzalkonium chloride (BAC) and the Czechoslovak detergent Jar were tested in vitro as well as in vivo. Experiments in vitro were performed on corneas of bovine eyes incubated at 37 degC. During a 10 min span the corneal surface was wetted with nine drops of aqueous solutions of BAC (0.001%, 0.01%, 0.1%, 1% and 10.0%, resp.) and Jar (0.01%, 0.1%, 1.0%, 10.0% and 100.0%, i.e., commercialy available compound, resp.). Changes of corneal permeability caused by detergents were demonstrated by an increaseJ uptake of ²²Na transferred from the paper strips stretched over the corneal surface. For the controls, saline was used instead of detergents. The corneal permeability for ²²Na increased with increasing detergent concentration. Significant changes of corneal permeability were caused by Jar diluted to 0.01%. Experiments in vivo were carried out on rabbits. Both detergents were tested in above mentioned concetrations using always two drops during a 1 min exposure. The eyes were observed for 6 days. Heavy keratitis with corneal edema, purulent conjunctival discharge and blepharitis was caused by 10% BAC and to a lesser degree also by 1% BAC or undiluted Jar. On the seventh day the permeability of the rabbit corneas was tested applying the paper strips soaked with ²²Na. After 30 min the rabbits were dissected and the radioactivity of the isolated tissues and aqueous has been evaluated. After the six days delay the functional changes of the epithelial barrier were still observable manifesting itself by changed permeability and ocular distribution of ²²Na. (author)

No abstract available

[en] The transport was studied of rubidium and sodium through the rabbit cornea aiming at ascertainment of whether or not corneal permeability was different for both elements, of the dynamics of elimination of both elements and how the processes were affected by equinormal salts and hydroxides used in the application of sodium and rubidium cations. ²²Na and ⁸⁶Rb were used as tracers. Stripes of chromatographic papers were saturated with ²²NaCl, ²²NaOH, ⁸⁶RbCl and ⁸⁶RbOH, respectively and applied to the corneas of experimental animals. The rabbits were sacrificed immediately, 10 and 60 min after administration. Radioactivity measurements were carried out in the chromatographic stripes removed from the rabbit eyes, in cut-off corneas, in intracorneal fluid samples, and in the rest of the bulb tissue. The penetration was found much higher for cations contained in hydroxides rather than in salts while the difference between sodium and rubidium was negligible. The retention of ⁸⁶Rb after 60 min was significantly higher than that of ²²Na and the elimination was significantly higher for the cations contained in hydroxides than in salts. Nearly all radioactivity in the hydroxides was accounted for ⁸⁶Rb whose penetration was slow and retention time long while ²²Na penetrated in a significantly lower amount and its retention was shorter. On the other hand, while the transport of both cations through the eye chamber fluid initially was considerably high, later, mainly in the third observation period ⁸⁶Rb was present in a significantly lower amount, probably due to the fact that it was still bound to the cornea, this in much greater extent than ²²Na. The method was proved to be simple, selective and reproducible and only required the minimum amount of radioisotopes, being thus favourable as regards costs and radiation hazards. (L.O.)

No abstract available

[en] The effect of fluoride ions given in a low concentration corresponding to that in drinking water on the metabolism of calcium in mechanically damaged long bones of rats was studied in experiments. ⁴⁵Calcium microdistribution in the growth zone and callus was studied using contact autoradiography of bone cuts on ORWO AF 4 nuclear emulsions. Photometry of the autoradiographs revealed differences between animals exposed to fluoride ions. (author)