Mutation of conserved aspartates affect maturation of presenilin 1 and presenilin 2 complexes.

Presenilin (PS1 and PS2) holoproteins are transiently incorporated into low molecular weight (MW) complexes. During subsequent incorporation into a higher MW complex, they undergo endoproteolysis to generate stable N- and C-terminal fragments (NTF/CTF). Mutation of either of two conserved aspartate residues in transmembrane domains inhibits both presenilin-endoproteolysis and the proteolytic processing of APP and Notch. We show that aspartate-mutant holoprotein presenilins are not incorporated into the high molecular weight, NTF/CTF-containing complexes. Aspartate-mutant presenilin holoproteins also preclude entry of endogenous wild-type PS1/PS2 into the high molecular weight complexes, but do not affect the incorporation of wild-type holoproteins into lower molecular weight holoprotein complexes. These data suggest that the loss-of-function aspartate-mutants cause altered PS complex maturation, and argue that the functional presenilin moieties are contained in the high molecular weight presenilin NTF/CTF-containing complexes.

A preliminary open trial on interferon stimulator (SNMC) derived from Glycyrrhiza glabra in the treatment of subacute hepatic failure.

The efficacy of the interferon stimulator named Stronger Neo Minophagen-C (SNMC) derived form the plant G. glabra was studied at a dose of 40 or 100 ml daily for 30 days followed by thrice weekly intravenously for 8 wk in 18 patients of subacute hepatic failure due to viral hepatitis. The survival rate amongst these patients was 72.2 per cent, as compared to the earlier reported rate of 31.1 per cent in 98 patients who received supportive therapy (P < 0.01). Death in four of the five patients was due to associated infections leading to hepatorenal failure and terminal coma. Further studies are necessary to standardize the dose and duration of therapy with SNMC in subacute hepatic failure.