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Biomedical subjects

L A Khan

Publications and source records attributed to L A Khan.

26 records · Page 2Linked to original sources
PubMed1993

Hypoglycaemic activity of Coccinia indica and Momordica charantia in diabetic rats: depression of the hepatic gluconeogenic enzymes glucose-6-phosphatase and fructose-1,6-bisphosphatase and elevation of both liver and red-cell shunt enzyme glucose-6-phosphate dehydrogenase.

Coccinia indica leaves were extracted with 60% ethanol, solvents were evaporated and the residue was suspended in water. This suspension was administered orally at a dose of 200 mg/kg body wt. after 18 h of fasting to normal fed and streptozotocin-induced male diabetic rats (180-250 g). After 90 min the rats were killed, and blood-glucose, hepatic glucose-6-phosphatase, fructose-1,6-bisphosphatase and glucose-6-phosphate dehydrogenase (G6PDH) and red-cell G6PDH were assayed. Blood sugar was depressed by 23% (P < 0.01) and 27% (P < 0.001) in the normal fed and streptozotocin-diabetic rats respectively compared with controls which were given distilled water. Hepatic glucose-6-phosphatase and fructose-1,6-bisphosphatase activities were depressed by 32% (P < 0.001) 30% (P < 0.05) respectively in the streptozotocin-diabetic rats, compared with 19% (P < 0.02) and 20% (P < 0.01) depression in the normal fed controls, whereas both the red-cell and hepatic G6PDH activities were found to be elevated by feeding the extract in the streptozotocin-diabetic and in the normal fed controls. Similar results were obtained with the 95%-ethanolic extract of Momordica charantia. Taken together, these results indicate that Coccinia indica and Momordica charantia extracts lowered blood glucose by depressing its synthesis, on the one hand through depression of the key gluconeogenic enzymes glucose-6-phosphatase and fructose-1,6-bisphosphatase and on the other by enhancing glucose oxidation by the shunt pathway through activation of its principal enzyme G6PDH.

Animals↗
PubMed1993

Potentiometric stripping analysis of selected heavy metals in biological materials.

Different biological materials such as edible oils, refined and unrefined cane and beet sugar and tea (black and green) leaves were assayed for the heavy metals cadmium, copper, lead and zinc. The results revealed significant differences in heavy metal contents within each class of the biological materials (P < 0.05). Cadmium was not detectable in sugar samples. Among the oils, highest amounts of copper (0.263 microgram/g) and lead (0.154 microgram/g) were in corn oil and zinc in olive oil (3.01 micrograms/g) whereas cadmium exhibited a narrow range (0.023-0.033 microgram/g). The samples of beet-sugar generally contained higher levels of the heavy metals than cane-sugar. Black and green tea leaves contained 0.411-0.908 microgram Cd/g, 6.500-9.220 micrograms Cu/g, 2.200-5.238 micrograms Pb/g, and 14.500-25.180 micrograms Zn/g.

Carbohydrates↗
PubMed1993

Extracorporeal shock wave lithotripsy for bladder stones.

Between December 1989 and July 1991, 29 patients with bladder stones were treated on the MPL 9000 extracorporeal shock wave lithotriptor using ultrasound for localisation. The mean stone dimensions were 22.65 x 15.17 mm (< 400 mm2 in 20 patients); 75% of patients required only 1 ESWL session but the largest stone (2025 mm2) required 3. Whilst larger stones tended to require more shock waves, linear regression analysis showed a poor fit and factors other than size (operator experience and stone hardness) may determine the number of shock waves required. Satisfactory fragmentation was obtained in all patients. All were treated under intravenous analgesia without anaesthesia. Three patients also had outflow obstruction and were treated by transurethral resection of the prostate (TURP) on the day after completing ESWL. ESWL prior to TURP reduces the morbidity and operating time associated with endoscopic therapy of bladder stones. Macroscopic fragments remaining after ESWL can be washed out at TURP.

Adolescent↗
PubMed1993

Proton liberation in the pre-steady state phase of creatine kinase.

Numerous stereochemical and kinetic investigations on the reaction pathway of creatine kinase (CK) suggest that this enzymic reaction proceeds via direct in-line transfer of phosphate between participating substrates and to date there has been no chemical evidence for any plausible intermediate between enzyme-substrate and enzyme-product complexes. By following the absorption pattern of a pH sensitive dye (o-cresol sulphonaphthalein) in a stopped flow module we have studied transient pH changes in the backward reaction of CK. While the rapid mixing of ADP and CK gives no pH transient, that of phosphocreatine (PCr) and CK gives H+ liberation with kapp of 62.8 sec-1. The magnitude of proton release is one H+ per monomer of CK. Mixing of PCr+CK with ADP does not give any detectable pH transient and the reaction immediately proceeds to steady phase. The mixing of ADP+CK with PCr again gives a release of 1.2 H+ per monomer of CK with kapp of around 67.2 sec-1 before the reaction proceeds to steady phase where there is absorption of one H+ per ADP transphosphorylated. The results obtained, therefore, indicate the involvement of proton deficient E.PCr and E.ADP.PCr complexes in the pathway of CK.

Adenosine Diphosphate↗
PubMed1989

Coupling of the enzymic activities of myosin ATPase and creatine kinase and its role in muscular contraction.

During muscular contraction the regeneration of ATP, catalysed by creatine kinase (CK), keeps pace with the hydrolysis of ATP by myosin ATPase posing the question of its regulatory mechanism. In the background of F-actin activation of heavy meromyosin (HMM) ATPase activity we have investigated in vitro the role of F-actin in regulating CK's activity in the absence and presence of HMM. For the coupled enzyme system we have also looked into the roles played by the individual reactants. F-actin has been found to appreciably increase CK's activity in the absence of HMM. While HMM alone inhibited CK's activity, there was a several fold increase when F-actin was also present. By a process of elimination we conclude that none of the reactants apart from H+ could be involved in regulating CK's activity in the coupled enzyme system. As no change in the pH of reaction mixture was observed during the reaction, we further conclude that the two enzymic reactions are coupled by proton transfer along F-actin. Implications of the findings for PCr-Cr shuttle and movements of ATP and ADP in sarcomere are discussed.

Actins↗
PubMed1989

The denatured states of ribonuclease-A: mechanism of denaturation by lithium chloride.

Denaturation of ribonuclease-A by lithium chloride has been studied using difference spectral, circular dichroic and viscometric measurements. The difference spectral results were interpreted in the light of our observations that the solvent effect of the denaturant on the tyrosyl residue is non-linear. It has been observed that (1) the lithium chloride-denatured protein contains 3% alpha-helix and 18% beta-structure, and (2) only two of the three buried tyrosyl residues are normalized in the denatured protein.

Chlorides↗