Biomedical subjects

H Kasama

Publications and source records attributed to H Kasama.

3 recordsLinked to original sources

PubMed1989

Differential effects of methylmercury on the synthesis of protein species in dorsal root ganglia of the rat.

Dorsal root ganglia from control and methylmercury (MeHg)-treated rats were incubated in vitro with 35S-methionine ant the proteins synthesized were analyzed by two-dimensional electrophoresis. The double labelling method, in which proteins of control dorsal root ganglia labelled in vitro with 3H-leucine were added to each of the two samples as an internal standard, was used to minimize unavoidable errors arising from the resolving procedure itself. The results obtained showed that the effect of MeHg on the synthesis of proteins in dorsal root ganglia was not uniform for individual protein species in the latent period of MeHg intoxication. Among 200 protein species investigated, 157 showed inhibition of synthesis close to that of the total proteins in the tissue (68% of the control). Among the remaining protein species, 20 showed real stimulation of synthesis, whereas 7 were moderately inhibited and 16 were inhibited more strongly than the total proteins in the tissue. These results suggest that the effect of MeHg on the synthetic rates for protein species in dorsal root ganglia differs with the species, and that unusual elevation or reduction of the synthesis of some protein species caused by MeHg may lead to impairment of normal nerve functions.

Animals↗

PubMed1987

Decrease in protein phosphorylation in central and peripheral nervous tissues of methylmercury-treated rat.

The protein phosphorylation in extracts of nervous tissues of rats acutely exposed to methylmercury chloride (seven daily injections of 10 mg methylmercury chloride/kg body weight) was examined. In the brain, the phosphorylating activity was dependent on cAMP and Mg2+. The effect of methylmercury on the phosphorylation of brain proteins, including tubulin and MAP-2, was hardly discernible. In peripheral nervous tissues such as the dorsal and ventral roots, sciatic nerves and dorsal root ganglia, the phosphorylating activity was dependent on Ca2+, and the maximal activity was obtained when the tissues were extracted in the presence of 1% Triton X-100. SDS-Polyacrylamide gel electrophoresis revealed that the major phosphorylated proteins in the peripheral tissues were myelin proteins. The effects of methylmercury were not uniform regarding protein species and tissues. The most marked changes were observed in sciatic nerves, in which phosphorylation of the 33 kDa, 28 kDa, 19 kDa, 18 kDa and 15 kDa proteins was significantly decreased in the symptomatic phase of intoxication.

Animals↗

PubMed1986

Species difference between rat and hamster in tissue accumulation of mercury after administration of methylmercury.

The accumulation of mercury in tissues of the rat and hamster was determined after the administration of a single dose of 203Hg-methylmercury chloride (10 mg/kg body weight). On day 2, the mercury contents of hamster tissues were higher than those of rat tissues, except for red blood cells, in which the mercury content was about 6-fold higher in the rat than in the hamster. After that time, the mercury content of hamster tissues decreased rather steeply and on day 16 it had reached 14-25% in nervous tissues and 7-15% in other tissues, of the levels on day 2. In the rat, on the other hand, the mercury content of nervous tissues on day 16 was higher than that on day 2 (106-220%), except for dorsal roots and dorsal root ganglia, which showed slight decreases (75-94% of the levels on day 2). In non-neural tissues, the decreases up to day 16 were also small (71-92% of the levels on day 2). Thus, both the uptake and elimination of mercury seem to be more rapid in the tissues of hamster compared with those of the rat. Similar trends of mercury accumulation and elimination were observed when animals received multiple injections of methylmercury that induced acute methylmercury intoxication. Significant biotransformation of the injected methylmercury to inorganic mercury was detected in the liver, kidney and spleen of both animal species.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗