Heterogeneity of the genes encoding the major surface glycoprotein of Leishmania donovani.

The major surface glycoprotein of Leishmania (GP63) is present on all known species of Leishmania and likely plays an integral role during the infection of macrophages in the mammalian host. To identify regions of GP63 which may be of functional significance, the nucleotide sequence of a gene encoding GP63 of Leishmania donovani was determined and compared to the sequences reported for GP63 genes of Leishmania major and Leishmania chagasi. The GP63 nucleotide and predicted protein sequence was highly conserved among the 3 species despite their diverse geographical distribution. L. donovani GP63 is encoded by a multigene family and the gene locus contains at least 7 tandemly repeated genes and at least 3 genes which are dispersed from the tandem array. In addition, polymerase chain reaction and Southern blot analyses demonstrated that there was size heterogeneity within the pro-peptide coding regions of the multiple GP63 genes of L. donovani and that such genes were expressed concurrently in the promastigote life stage.     

Central pontine myelinolysis in liver transplantation.

Five cases of central pontine myelinolysis (CPM) were detected by neuropathological examination in a series of 50 patients coming to necropsy after liver transplantation. One patient also had extrapontine myelinolysis. In no case was the diagnosis made during life. Only two patients showed rapid rises in serum sodium concentrations. The incidence of hyponatraemia, before and after transplantation, and rapid rises in serum sodium in patients with CPM was significantly greater than in the 45 patients showing no neuropathological evidence of CPM. It is concluded that there is a high incidence of CPM after liver transplantation, that clinical diagnosis is difficult, and that there is no simple direct correlation between rapid serum sodium changes and the development of this condition. Avoidance of major electrolyte fluctuations at the time of liver transplantation is recommended but it must be emphasised that CPM may occur without any rapid rise in serum sodium concentration.     

Effects of exercise on behavioral sensitivity to carbamate cholinesterase inhibitors

The interaction between exercise and drug response has not been studied extensively. The present study examined the relationship between both acute (15 minute) and chronic (10 week) treadmill exercise and behavioral response to the carbamates physostigmine and pyridostigmine. Rats trained on an operant task under a multi-component FR30 schedule were used to evaluate the interaction between exercise and performance following drug administration. The direct effects of both 10 weeks of exercise conditioning and a moderate exercise challenge, as well as the interaction between two were assessed. Results obtained with physostigmine show that acute exercise increased behavioral sensitivity. Chronic exercise resulted in behavioral tolerance. These results are consistent with previously reported studies of centrally acting compounds. In contrast, pyridostigmine, which has little or no central activity, produced no behavioral changes. This result was constant over exercise conditions.     

Common bile duct calculi: updated experience with dissolution with methyl tertiary butyl ether

The authors describe their experience with methyl tertiary butyl ether (MTBE) in a larger series of patients than previously reported in order to acquaint physicians with both its effectiveness for dissolution of common bile duct calculi and the limitations of its use. Ten patients with 13 biliary calculi underwent percutaneous stone dissolution treatment with the experimental cholesterol solvent, MTBE. Three stones completely dissolved within 30 minutes, seven were reduced in size, and three were visibly unaffected. All stones not completely dissolved were easily extracted by means of a stone basket except for one in a patient taken to surgery. Although MTBE perfusion is an effective technique for management of biliary calculi, practitioners should be aware that its use is quite time consuming and its odor difficult to control.