Search Results
You are looking at 1 - 4 of 4 items for
- Author: Y H A Abdel-Wahab x
- Refine by access: All content x
Search for other papers by AMAL M. SAEED in
Google Scholar
PubMed
Search for other papers by H. A. EL MUNSHID in
Google Scholar
PubMed
Search for other papers by M. Y. SUKKAR in
Google Scholar
PubMed
Search for other papers by S. M. ABDEL WAHAB in
Google Scholar
PubMed
Departments of Physiology and Pathology, Faculty of Medicine, University of Khartoum, P.O. Box 102, Khartoum, Sudan
(Received 31 October 1977)
The important role of the kidney in the degradation and excretion of insulin has recently been reviewed (Rubenstein & Spitz, 1968; Rubenstein, Mako & Horwitz, 1975). The kidney functions with a wide margin of safety but the minimum functional renal mass required for the effective elimination of insulin is not known. The present report deals with the effects of total and five-sixths nephrectomy on the concentrations of insulin and glucose in the blood. The effects of uraemia itself, produced by bilateral ureteric ligation, have also been studied.
Albino rats of the Wistar strain (mean weight 232 ± 5 (s.e.m.) g) were used. Except for ten female rats included in the acutely uraemic group, the remainder of the animals were male. The subsequent operations were performed under open diethyl ether anaesthesia
Search for other papers by L Marenah in
Google Scholar
PubMed
Search for other papers by P R Flatt in
Google Scholar
PubMed
Search for other papers by D F Orr in
Google Scholar
PubMed
Search for other papers by C Shaw in
Google Scholar
PubMed
Search for other papers by Y H A Abdel-Wahab in
Google Scholar
PubMed
Skin secretions of Rana saharica were evaluated for the isolation and characterisation of novel insulinotropic peptides. Crude secretions obtained from young adult frogs by mild electrical stimulation of the dorsal skin surface were purified by reverse phase HPLC yielding 80 fractions. In acute 20-min incubations with glucose responsive BRIN-BD11 cells, fractions 36–43, 46–54 and 57–63 significantly stimulated insulin release by 2- to 8-fold compared with 5.6 mM glucose alone. Pooled fractions in the latter two bands were rechromatographed to reveal 9 homogenous peaks, which elicited significant 1.3- to 3.5-fold increases in insulin release (P < 0.05). Structural analysis of the most potent non-toxic peptides was performed by mass spectrometry and automated Edman degradation. This revealed four major insulin-releasing peaks with molecular masses of 2676.9 Da, 3519.3 Da, 4920.4 Da and 4801.2 Da respectively. These peptides were found to be identical to brevinin-1E, brevinin-2EC, esculentin-1 and esculentin-1B, which belong to the group of antimicrobial peptides isolated from skin secretions of various Rana frog species. Preliminary studies on the mechanism underlying the insulinotropic actions of esculentins-1 and -1B suggested possible involvement of both cyclic AMP–protein kinase A and –C-dependent G-protein sensitive pathways. These data indicate that the skin secretions of Rana saharica frogs contain bioactive molecules with significant insulin-releasing activity. Relatives of the brevinin/esculentin peptide family merit further investigation as novel insulin secretagogues.
Department of Pharmacology, Biomedical Research Group, BIRDEM, Dhaka-1000, Bangladesh
Search for other papers by J M A Hannan in
Google Scholar
PubMed
Department of Pharmacology, Biomedical Research Group, BIRDEM, Dhaka-1000, Bangladesh
Search for other papers by L Marenah in
Google Scholar
PubMed
Department of Pharmacology, Biomedical Research Group, BIRDEM, Dhaka-1000, Bangladesh
Search for other papers by L Ali in
Google Scholar
PubMed
Department of Pharmacology, Biomedical Research Group, BIRDEM, Dhaka-1000, Bangladesh
Search for other papers by B Rokeya in
Google Scholar
PubMed
Department of Pharmacology, Biomedical Research Group, BIRDEM, Dhaka-1000, Bangladesh
Search for other papers by P R Flatt in
Google Scholar
PubMed
Department of Pharmacology, Biomedical Research Group, BIRDEM, Dhaka-1000, Bangladesh
Search for other papers by Y H A Abdel-Wahab in
Google Scholar
PubMed
Ocimum sanctum leaves have previously been reported to reduce blood glucose when administered to rats and humans with diabetes. In the present study, the effects of ethanol extract and five partition fractions of O. sanctum leaves were studied on insulin secretion together with an evaluation of their mechanisms of action. The ethanol extract and each of the aqueous, butanol and ethylacetate fractions stimulated insulin secretion from perfused rat pancreas, isolated rat islets and a clonal rat β-cell line in a concentration-dependent manner. The stimulatory effects of ethanol extract and each of these partition fractions were potentiated by glucose, isobutylmethylxanthine, tolbutamide and a depolarizing concentration of KCl. Inhibition of the secretory effect was observed with diazoxide, verapamil and Ca2+ removal. In contrast, the stimulatory effects of the chloroform and hexane partition fractions were associated with decreased cell viability and were unaltered by diazoxide and verapamil. The ethanol extract and the five fractions increased intracellular Ca2+ in clonal BRIN-BD11 cells, being partly attenuated by the addition of verapamil. These findings indicated that constituents of O. sanctum leaf extracts have stimulatory effects on physiological pathways of insulin secretion which may underlie its reported antidiabetic action.
Search for other papers by Y H A Abdel-Wahab in
Google Scholar
PubMed
Search for other papers by F P M O'Harte in
Google Scholar
PubMed
Search for other papers by C R Barnett in
Google Scholar
PubMed
Search for other papers by P R Flatt in
Google Scholar
PubMed
Abstract
Characteristics of cellular insulin glycation were examined in the pancreatic B-cell line, BRIN-BD11. The extent of insulin glycation increased stepwise during 72 h of culture at 5·6–33·3 mmol/l glucose, attaining levels up to 27%. Glycation of insulin at 33·3 mmol/l glucose was rapid, reaching maximal values within 2 h, and not readily reversible during 2 to 24 h of subsequent exposure to 5·6 mmol/l glucose. Glycated insulin was readily secreted by BRIN-BD11 cells upon active stimulation with glucose and other secretagogues. Cellular insulin glycation was decreased by 66–80% by inhibitors of protein glycation, vitamin C, aminoguanidine or acetylsalicylic acid. Modulation of insulin-secretory activity of BRIN-BD11 cells by co-culture at high glucose with diazoxide, l-alanine or glibenclamide indicated that long-term stimulation of secretion was associated with a decrease in the extent of insulin glycation. Glycation of insulin in vitro was substantially less extensive than in BRIN-BD11 cells, although glucose-6-phosphate and glyceraldehyde-3-phosphate were 1·4- to 2·0-fold more reactive than glucose per se. These observations indicate that insulin is readily glycated and secreted from insulin-secreting cells under hyperglycaemic conditions in culture.
Journal of Endocrinology (1997) 152, 59–67
