RESUMEN
Mebendazole and thiabendazole were found to inhibit glucose uptake and its metabolism in the adult rat hookworm (N. brasiliensis) in vitro. Rates of endogenous glycogen utilisation, and excretion of one of the end products of glycolysis viz., lactic acid, were found to be increased, when the intact N. brasiliensis adults were incubated for 60 min with mebendazole and thiabendazole, respectively.
Asunto(s)
Mebendazol/farmacología , Nippostrongylus/efectos de los fármacos , Tiabendazol/farmacología , Animales , Glucógeno/metabolismo , Lactatos/metabolismo , Ácido Láctico , Masculino , Nippostrongylus/metabolismo , RatasRESUMEN
Spermidine was detected as the major polyamine of Ancylostoma ceylanicum as well as Nippostrongylus brasiliensis. Spermine was present in lower amounts whereas the level of putrescine was even less. S-Adenosylmethionine decarboxylase, a rate-limiting enzyme in the biosynthetic pathway of polyamines, was demonstrated at low levels in both parasites. Decarboxylation of lysine and arginine was absent or negligible and that of ornithine questionable, as the enzyme activity was not inhibited by alpha-difluoromethylornithine while RMI 71,645, an irreversible inhibitor of ornithine aminotransferase, strongly inhibited the liberation of CO2 from ornithine. High activity of ornithine aminotransferase was observed in both the parasites and may interfere with the assay for ornithine decarboxylase. Adults of A. ceylanicum were found to rapidly take up spermidine and spermine from incubation medium while uptake of putrescine was very low. These results indicate that hookworms depend on uptake and interconversion rather than de novo synthesis for their polyamine requirement.
Asunto(s)
Ancylostoma/metabolismo , Nippostrongylus/metabolismo , Poliaminas/metabolismo , Ancylostoma/enzimología , Animales , Nippostrongylus/enzimologíaRESUMEN
The presence of cyclic AMP-dependent protein kinase and phosvitin kinases, with activity independent of cyclic nucleotides, was shown in the intestinal nematode Nippostrongylus brasiliensis. The activity of the cyclic AMP-dependent protein kinase was found to be enhanced about 8-fold in the presence of 10(-7) M cyclic AMP; the apparent Km values were determined to be 20 microM and 80 microM for ATP and kemptide, respectively. The molecular weight of the holoenzyme was about 170 000. Two phosvitin kinases could be isolated and distinguished by their molecular weights of 600 000 and 40 000. The activity of the high-molecular-weight phosvitin kinase was effectively inhibited by suramin and heparin. The apparent Km values were found to be 30 microM and 0.1 mg/ml for ATP and phosvitin, respectively. In the case of the low-molecular-weight phosvitin kinase the apparent Km values for ATP and phosvitin were found to be 30 microM and 0.6 mg/ml, respectively. The investigation of different developmental stages of N. brasiliensis revealed a marked higher level of protein kinase activity in the L4 larvae compared to L3 larvae and adults.