[Inhibitory effect of asymmetric dimethylarginine and NG-Monomethyl-L-arginine methyl ester on nitric oxide synthase activity]

Nitric oxide synthase [NOS] paly a role in nitric oxide [NO] generation. Despite the beneficial effects of NO on different body systems its overproduction of produce reactive nitrogen species [RNS] and nitrosilation of proteins. This study was done to evaluate the effect of asymmetric dimethylarginine [ADMA] and NG-Monomethyl-L-arginine methyl ester [L-NMMA] on inhibition of nitric oxide synthase activity. In this laboratory study, Nitric oxide synthase was extracted from 500 grams of sheep kidney by homogenization, ammonium sulphate precipitation and column chromatography on DEAE-32 Cellulose and 2', 5'-ADP-agarose. During purification, protein content was measured according to the Bradford and enzyme activity was assayed using the Griess reactions the inhibitory effects of 25 micro concentrations of ADMA and L-NMMA on purified enzyme were determined. Specific activity and yield of NOS were 0.6 units/mg protein and 0.9%, respectively. Molecular weight of purified enzyme was 54 KD with SDS-PAGE. ADMA and L-NMMA in 25 micro concentrations reduced enzyme activity by 76 and 61.2%, respectively. Km values for NOS in absence and in presence of ADMA and L-NMMA were 5.32 microM, 31.25 microM [P<0.05] and 14.29 microM [P<0.05], respectively. Vmax for NOS in absence and presence of inhibitors was not changed. ADMA and L-NMMA have competitive inhibitory effect on NOS activity and ADMA have higher inhibitory effect than L-NMMA

Thyroid stimulating hormone and leptin levels and severe growth retardation among beta - thalassemic patients

It has been proposed that Thyroid Stimulating Hormone [TSH] influences leptin secretion from adipocytes. We evaluated the association between TSH and leptin levels in thalassemic patients with growth retardation. Blood samples were collected from 30 major thalassemic patients and 24 normal subjects [range: 12 - 20 y]. Both Leptin and TSH were measured by Enzyme-Linked Immunosorbent Assay [ELISA] method. The anthropometric data were collected based on standard methods. Independent sample t-test and Pearson's correlation were used to analyze data. Patients had severe growth retardation. Mean concentration of leptin in thalassemic patients was significantly lower than normal subjects [2.26 +/- 2.61 vs 13.14 +/- 15.95 ng/ml]. The mean value of serum TSH concentration in beta - thalassemic patients was higher than normal subjects. But the difference was not statistically significant [P = 0.146]. There was no marked relationships between TSH and leptin concentrations in thalassemic patients [r= -0.022, P = 0.909] and in control group [r=0.289, P=0.214]. In both beta - thalassemic patients and normal group leptin secretion is not affected by TSH concentration

[Indentification and characterization of blood coagulation factor X activator from the venom of iranian vipera lebetina]

Snake venom particulary those belonging to Crotalidae and viperidae families, are known to contain number of components affecting blood coagulation. The Aim of this paper is to describe the isolation a specific blood coagulation factor X activator from the crude venom of Iranian Vipera lebetina. Factor X activator was purified from two hundred mg of crude venom by gel filtration on sephadex G-100 and two step ion-exchange chromatography on DEAE-cellulose [DEAE-52]. It showed a single band in sodium dodecyl sulfate-polyacrylamid gel electrophoresis [SDS-PAGE] in non-reducing condition. The mol. wt was estimated to be 78000Da by SDS-PAGE the activator, activated factor X to Xa in presence of calcium ions. It could not activate prothrombin, no had effect an fibrinogen and thus appeared to act specifically on factor X. The activator no amidolytic activtiy on factor Xa substrate benzoyl-Ile-glu-Gly-Arg-p-nitracnilide [S-2222]. It had no arginine esterase activity toward substrate benzoylagrinine ethylester [BAEE] while crude venom hydrolyzes this substrate. The results of this study showed that The activator do act specifically on factor X

[Study the effect of oxamate on rat sperm motility in vivo]

LDH- C4 is an isoenzyme of lactate dehydrogenase that is found in mature testes and spermatozoa of species with internal fertilization. Its physiological function appears related to metabolic processes that provide energy for motility and survival of spermatozoa. Oxamate is a new selective competitive inhibitor of sperm LDH- C4 with pyruvate as substrate. In the present experimental study on male rat, the effectiveness of oxamate was evaluated as a novel approach to the development of a male contraceptive. In this study, 20 adult rats were divided into 4 groups, the first used as control and the remaining three used as experimental groups. Experimental groups received different concentration, of oxamate [150, 300, 600 mg/kg/,ip] for 45 days. Control animals received normal saline solution. The sperms from the cauda division of epididymidis were collected by placing minced cauda in culture medium [T6] for one hour at 37°C in a 5% CO[2] atmosphere. Sperm motility was evaluated utilizing Makler chamber and compared with the control group. Statistical analysis was performed by the student t- test and one - way ANOVA. Progressive sperm motility in control and treated their groups were%60.3 +/- 2.8],%50 +/- 2.4],%41.5 +/- 1.9],%19 +/- 2.2] respectively. We conclude that oxamate in vivo can reduce sperm motility significantly and this reduction was concentration-dependent. The results of this work show that sperm motility can be reduced by concentration- dependent effect of oxamate under in vivo conditions

[Selective and non-selective inhibition of nitric oxide synthase in the in-vitro model of gentamicin-induced acute renal failure in rats]

All the three nitric oxide synthase [NOS] isoforms are presented in the kidney. Some data provided evidences that eNOS activity leads to restoration of renal function after injury, but activation of iNOS aggravates renal failure. In the present study, we investigated that whether in gentamicin-induced renal failure selective iNOS blockade is beneficial. Four groups of rats were studied: Control with saline injections; gentamicin [GM] with GM injections only [iv, 4 mg/kg]; GM + L-NAME: N-omega -L-arginine methyl ester [L-NAME] administrated simultaneously with [iv, 30 mg/kg] or two and four hours after GM [ip,30 mg/kg]; GM + L-NIL: N-imino-ethyil lysine [L-NIL] administrated simultaneously with [iv, 3 mg/kg] or two and four hours after GM [ip,3 mg/kg]. In all groups, serum and urine creatinine were measured. Creatinine clearance were calculated and considered as GFR. Urine N-acethyle-b-D - glocose aminidase [NAG] was assayed. After surgery, kidney sections were histologically studied. GFR was significantly lower in GM group compared to control and L-NIL groups [P<0.01]. It was also lower in L-NAME group compared to GM group [P<0.05]. Creatinine levels were significantly higher in GM group compared to that of control ones [P<0.01]. L-NIL group had lower creatinine levels when compared to GM group. NAG had higher activities in the urine of GM group when compared to the controls [P<0.01]. Enzyme activities in L-NIL group were numerically between the control and GM groups. L-NAME increased GM-induced enzyme release [P<0.05]. Histological studies showed that GM-treated kidneys had clear evidences of tubular damages and these damages were decreased by simultaneous administration of L-NIL and GM, although not significant. Selective inhibition of iNOS by L-NIL may prevent whereas, non-selective inhibition of NOS by L-NAME aggravates GM-induced renal failure

Effect of chemical modification induced by copper oxidation on lipoprotein [a] binding site function

High Lp[a]level in human serum appears to be associated with increased risk for athero- thrombosis. Pathogenecity of Lp[a] as a risk factor may depend on its lysine binding site [LBS] activity, which imparts a unique function to Lp[a], including a potential to inhibit fibrinolysis. Lp[a] is present in human plasma in four heterogeneous subspecies: [Lp[a]Lys-, Lp[a]Lys+1, Lp[a]Lys+2, Lp[a]Lys+3]. This subclassification is made according to their ability to bind to lysine sepharose. Data available indicate that serum lipoproteins are sensitive to copper-induced oxidation. In this study the effect of copper oxidation on lysine binding site properties of Lp[a] was investigated, to find information about molecular mechanism of Lp[a] in promoting thrombosis and atherosclerosis. Serum lipids were oxidized in the presence of 15,30,50,75 and 100 micro m of CuCl2. Lipid oxidation was measured as conjugated diene formation determined by spectrophotometric method at 245 nm. Four species of Lp[a] in the oxidized serum were isolated using affinity chromatography on lysine sepharose. Results showed a concentration-dependent increase in all subtypes of Lp[a]Lys+ and a decrease in all subtypes of Lp[a] Lys-. These data suggest that copper ion can induce a chemical modificaton to lipoprotein[a] leading to an increase in LBS activity of Lp[a], and thus, can promote athero- thrombosis