Protective effect of Hypericum perforatum Linn (St. John's wort) against hydrogen peroxide-induced apoptosis on human neuroblastoma cells

The medicinal plant Hypericum perforatum Linn, commonly known as St. John's wort, has been used as an antidepressant. To investigate whether St. John's wort possesses a protective effect against hydrogen peroxide (H(2)O(2))-induced cytotoxicity in neuronal cells, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, 4,6-diamidino-2-phenylindole staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, flow cytometry analysis, DNA fragmentation assay, and caspase-3 enzyme assay were performed on SK-N-MC human neuroblastoma cells. Cells treated with H(2)O(2) exhibited several apoptotic features, while those pre-treated with St. John's wort prior to H(2)O(2) exposure showed a decreased occurrence of apoptotic features. In addition, pre-treatment with St. John's wort inhibited H(2)O(2)-induced increase in caspase-3 enzyme activity. These results suggest that St. John's wort may exert a protective effect against H(2)O(2)-induced apoptosis in human neuroblastoma cells.     

No evidence of PEG1/MEST gene mutations in Silver‐Russell syndrome patients

Silver‐Russell syndrome (SRS) is characterized by prenatal and postnatal growth retardation with morphologic anomalies. Maternal uniparental disomy 7 has been reported in some SRS patients. PEG1/MEST is an imprinted gene on chromosome 7q32 that is expressed only from the paternal allele and is a candidate gene for SRS. To clarify its biological function and role in SRS, we screened PEG1/MEST abnormalities in 15 SRS patients from various standpoints. In the lymphocytes of SRS patients, no aberrant expression patterns of two splice variants (α and β) of PEG1/MEST were detected when they were compared with normal samples. Direct sequence analysis failed to detect any mutations in the PEG1/MEST α coding region, and there were no significant mutations in the 5′‐flanking upstream region containing the predicted promoter and the highly conserved human/mouse genomic region. Differential methylation patterns of the CpG island for PEG1/MEST α were normally maintained and resulted in the same pattern as in the normal control, suggesting that there was no loss of imprinting. These findings suggest that PEG1/MEST can be excluded as a major determinant of SRS. © 2001 Wiley‐Liss, Inc.     

Role of hydrophobic interaction in the enantioselective solvolyses of amino acid p-nitrophenyl esters by optically active imidazole-containing polymers

Solvolytic reactions of N-benzyloxycarbonyl-D -phenylalanine p-nitrophenyl ester and N-benzyloxycarbonyl-L -phenylalanine p-nitrophenyl ester by optically active imidazole-containing polymers were performed at different temperatures and in aq. ethanol of different water contents. The catalyst polymers employed were homopolymers of N-methacryloyl-L -histidine ( 1a ) and N-methacryloyl-L -histidine methyl ester ( 1b ), as well as copolymers of 1a with dodecyl methacrylate (DMA) and 1b with DMA. In 30 vol. -% aqueous ethanol at pH 7,02 the homopolymers did not show any enantioselective catalysis. However, the copolymers did exhibit enantioselective catalysis, viz., k_cat(L )/k_cat(D ) = 1,25 for poly ( 1b -co-DMA) containing 5,7 mol-% of DMA. As the reaction temperature was lowered, the reaction rate increased and the enantioselectivity was enhanced (k_cat(L )/k_cat(D ) = 1,67 for poly ( 1b -co-DMA) at 10°C). When the ethanol content was decreased, enhanced reaction rates and enantioselectivity (k_cat(L )/k_cat(D ) = 1,65 for poly ( 1 b -co-DMA) in 20 vol.-% aqueous ethanol) were observed. From these results it is concluded that hydrophobic interaction plays an important role in the enantioselective catalysis of optically active imidazole-containing polymers.     

Inhibition of lens-aldose reductase activity by brazilin and haematoxylin

Brazilin and haematoxylin, plant pigments, were examined for their effects on the Bovine-Lens aldose reductase (LAR)-activity. About 50% inhibition was observed in a concentration of 10 (-4) M-brazilin and 10 (-4) M-haematoxylin, and above 95% inhibition was observed in a concentration of 10 (-3) M-brazilin and 10 (-3)M-haematoxylin. In order to determine the type of inhibition, kinetic studies were also conducted with brazilin and haematoxylin, in which both were found to be noncompetitive inhibitors.     

Studies on the development of enzyme linked immunosorbent assay (ELISA) for hepatitis B surface antigen(HBsAg) by monoclonal antibodies of different affinity constants

Mouse monoclonal antibodies to Hepatitis B surface antigen(HBsAg) were prepared and their functional capabilities tested by the method of solid phase enzyme linked immuno sorbent assay(ELISA). HBsAg binding studies indicated that one monoclonal antibody 6E-1-1 bound more HBsAg at a faster rate than the other monoclonal antibodies. Also, for the binding inhibition studies with the selected monoclonal antibody 6E-1-1, one monoclonal antibody 8D-3-6 didn’t exhibit binding inhibition for HBsAg. Then, a simultaneous ELISA method was developed for the immunodiagnosis of HBsAg. Different combinations of two monoclonal antibodies as solid phase and horseradish peroxidase(HRPO) labeled phase were studied. The combination of monoclonal antibody of higher affinity constant (6E-1-1) immobilized in a solid phase and monoclonal antibody of lower affinity constant (8D-3-6) as a HRPO labeled phase was more sensitive when two monoclonal antibodies of different affinity constants for HBsAg were prepared.     

Central Regulation of Branched-Chain Amino Acids Is Mediated by AgRP Neurons

Circulating branched-chain amino acids (BCAAs) are elevated in obesity and diabetes, and recent studies support a causal role for BCAAs in insulin resistance and defective glycemic control. The physiological mechanisms underlying BCAA regulation are poorly understood. Here we show that insulin signaling in the mediobasal hypothalamus (MBH) of rats is mandatory for lowering plasma BCAAs, most probably by inducing hepatic BCAA catabolism. Insulin receptor deletion only in agouti-related protein (AgRP)–expressing neurons (AgRP neurons) in the MBH impaired hepatic BCAA breakdown and suppression of plasma BCAAs during hyperinsulinemic clamps in mice. In support of this, chemogenetic stimulation of AgRP neurons in the absence of food significantly raised plasma BCAAs and impaired hepatic BCAA degradation. A prolonged fasting or ghrelin treatment recapitulated designer receptors exclusively activated by designer drugs–induced activation of AgRP neurons and increased plasma BCAAs. Acute stimulation of vagal motor neurons in the dorsal motor nucleus was sufficient to decrease plasma BCAAs. Notably, elevated plasma BCAAs were associated with impaired glucose homeostasis. These findings suggest a critical role of insulin signaling in AgRP neurons for BCAA regulation and raise the possibility that this control may be mediated primarily via vagal outflow. Furthermore, our results provide an opportunity to closely examine the potential mechanistic link between central nervous system–driven BCAA control and glucose homeostasis.     

Mapping the effects of motor cortex stimulation on somatosensory relay neurons in the rat thalamus: Direct responses and afferent modulation

Single unit recordings were used to map the spatial distribution of motor (MI) cortical influences on thalamic somatosensory relay nuclei in the rat. A total of 215 microelectrode penetrations were made to record single neurons in tracks through the medial and lateral ventroposterior (VPM and VPL), ventrolateral (VL), reticular (nRt), and posterior (Po) thalamic nuclei. Single units were classified according to their: 1) location within the nuclei, 2) receptive fields, and 3) response to standardized microstimulation in deep layers of the forepaw-forelimb areas of MI cortex. For mapping purposes, only short latency (1-7 msec) excitatory neuronal responses to the MI cortex stimulation were considered. Percentages of recorded thalamic neurons responsive to the MI stimulation varied considerably across nuclei: VL: 42.6%, nRt: 23.0%, VPL: 15.7%, VPM: 9.3%, and Po: 3.9%. Within the VPL, most responsive neurons were found in "border" regions, i.e., areas adjacent to the VL, and (to a lesser extent) the nRt and Po thalamic nuclei. The same parameters of MI cortical stimulation were used in studies of corticofugal modulation of afferent transmission through the VPL thalamus. A condition-test (C-T) paradigm was implemented in which the cortical stimulation (C) was delivered at a range of time intervals before test (T) mechanical vibratory stimulation was applied to digit No. 4 of the contralateral forepaw. The time course of MI cortical effects was analyzed by measuring the averaged evoked unit responses of the thalamic neurons to the T stimuli, and plotting them as a function of C-T intervals from 5-50 msec. Of the 30 VPL neurons tested during MI stimulation, the average response to T stimulation was decreased a mean 43%, with the suppression peaking at about 30 msec after the C stimulus. This suppression was more pronounced in the VPL border areas (-52% in areas adjacent to VL and nRt) than in the VPL center (-25%).     

EFFICACY OF SUCRALFATE IN PREVENTING GASTROINTESTINAL SIDE EFFECTS OF NSAIDs

To find out the efficacy of sucralfate in preventing gastrointestinal side effects of non-steroidal anti-inflammatory drugs (NSAIDs) a prospective, randomised single blind study was conducted from 1989 to 1992. Patients with osteoarthritis, rheumatoid arthritis and other long standing painful conditions, who were expected to receive NSAIDs for over three months, were recruited into the study. All medicines were discontinued for a period of 10–15 days prior to initial endoscopic assessment. NSAID therapy was started and the patients were randomised to receive either placebo (group A) or sucralfate (group B) in addition. Patient were reassessed clinically every week and an endoscopic examination was repeated after 6–8 weeks of follow-up. A total of 176 patients were studied in group A (n=91) and group B (n=85). At the end of 8 weeks gastrointestinal symptoms were present in 30.6% and 26.4% patients of group A and B respectively. Endoscopic assessment showed superficial lesions in 36.5% and 18.7% while endoscopic ulcer in 2.4% and 1.1% patients of groups A and B respectively. Thus in patients receiving chronic NSAID therapy, simultaneous administration of sucralfate reduces the incidence of superficial gastric lesions but has no significant effect on symptoms or ulcer formation.KEY WORDS: Gastropathy, Sucralfate, Nonsteroidal anti-inflammatory drugs