Galactocerebroside mediates Ca2+ signaling in cultured glioma cells.

Expression of galactocerebroside (GalC) was detected in human glioma cell line (U-87 MG). Exposure of cells to antibody against GalC and fluoresceinated second antibody showed intense fluorescence on the plasma membrane. Possible involvement of GalC in receptor-mediated transmembrane signaling was explored in this cell line. Antibodies raised against GalC were used as ligands. Binding of anti-GalC to these cells caused a transient increase in intracellular free calcium ([Ca2+]i). The response was observed both in the presence and absence of extracellular calcium demonstrating that the rise in [Ca2+]i induced by anti-GalC was due to an influx of Ca2+ through plasma membrane as well as the release of Ca2+ from intracellular pools. Ca2+ influx was blocked by verapamil, indicating that influx is mediated by voltage-sensitive channels. Our results suggest that GalC can play a role in transmembrane signaling by modulation of voltage-sensitive Ca2+ channels.     

Persistence of heart reactive antibodies (HRA) in acute rheumatic fever (ARF) and rheumatic heart disease (RHD) patients

Heart Reactive Antibodies (HRA) of IgG and IgM classes were investigated in 79 patients in four clinically classified groups. Group I comprised of 16 children with Acute Rheumatic Fever (ARF) and Group II consisted of 15 cases with active Rheumatic Heart Disease (RHD). Twenty seven cases of ARF and RHD in remission and 21 adults with quiescent RHD were included in Groups III and IV respectively. Control groups comprised of 14 normal, healthy, donors and eight Post Streptococcal Acute Glomerular Nephritis (PSAGN) cases. Low levels of HRA of IgG and IgM classes were detected in control groups. The overall incidence of HRA of IgG and IgM classes was 82.28 and 39.24% respectively in the patient group. An increased frequency of HRA-IgM antibodies was observed in Groups I, III and IV (p less than 0.01, 0.001 and 0.025 respectively). All the four groups demonstrated a highly significant increase in incidence of HRA--IgG class (p less than 0.0005). Persistence of high titres of HRA-IgG class in ARF and RHD is reported in the paper.     

Biochemical changes in the liver of fish, Tilapia mossambica (Peters), during continuous exposure to monocrotophos

The purpose of the present investigation was to determine the effect of continuous exposure to the organophosphate monocrotophos at 2.5 ppm for over a period of 2 through 45 days on protein, RNA, and DNA contents and on 5'-nucleotidase activity in the liver of Tilapia mossambica. Protein content was decreased by 45% after 5 days, returned to control levels at 10-30 days, and again decreased by 45 days. DNA content was decreased by 2 days, returned to control values by 5 days, and remained constant throughout the exposure. In contrast, RNA content was significantly lower starting from 2 through 45 days of exposure. 5'-Nucleotidase activity showed a transient increase at 5 and 30 days of monocrotophos exposure. These results indicate that monocrotophos altered the protein, DNA, and RNA contents and the 5'-nucleotidase activity levels as early as 2 and 5 days. However, these changes were reversed by 10 days and after a short period of recovery, the alterations reappeared. This supports our earlier histological observations of hepatic pathology during monocrotophos exposure.