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Biomedical subjects

S Gür

Publications and source records attributed to S Gür.

11 recordsLinked to original sources
PubMed2005

Synthesis, in vitro cytotoxic and antiviral activity of cis-[Pt(R(-) and S(+)-2-alpha-hydroxybenzylbenzimidazole)2Cl2] complexes.

A pair of enantiomeric platinum(II) complexes of cis-[Pt(R(-) and S(+)-HBB)2Cl2] (HBB=2-alpha-hydroxybenzylbenzimidazole) was synthesized and evaluated for its preliminary in vitro cytotoxic activity on the human MCF-7 breast cancer and HeLa cervix cancer cell lines and antiherpes virus activity against bovine herpesvirus type 1 (BHV-1). In general, it was found that Pt(II) complexes were less cytotoxic on both cell lines than cisplatin and were comparable to carboplatin. There was no significant difference in cytotoxicity between two enantiomers, and the antiviral test results showed that the Pt(II) complexes and their carrier ligands R(-) and S(+) HBB had no effects inhibiting replication of BHV-1.

Animals↗
PubMed2003

Synthesis, characterization and in vitro cytotoxic, mutagenic and antimicrobial activity of platinum(II) complexes with substituted benzimidazole ligands.

In this study, six Pt(II) complexes bearing 5(6)-H or -CH(3)-2-phenyl or -(2'-pyridyl) or -mercaptomethylbenzimidazole ligands as 'carrier groups' were synthesized and characterized by elemental analysis, IR and (1)H-NMR spectra and evaluated for their preliminary in vitro cytotoxic activity to the human RD Rhabdomyosarcoma cell line and mutagenic properties in Salmonella typhimurium strains TA 98 and TA 100 in the absence of the S9 rat liver fraction. The preliminary test results showed that the complexes had slightly greater cytotoxic activity on the RD cell line at 1 microM concentration than cisplatin. Among the compounds tested for their mutagenicity, Pt(II) complexes of 2-(2'-pyridyl)- and 5(6)-methyl-2-(2'-pyridyl)benzimidazoles were found to be mutagenic. A comparative study of the MIC (minimum inhibitory concentration) values indicated that, in general, there were no differences between the poor antimicrobial activity values of the ligands and their Pt(II) complexes with respect to the tested microorganisms. These results suggest that the synthesized Pt(II) complexes should be considered for further antitumor activity studies.

Animals↗
PubMed2000

Direct inotropic effects of propofol and adenosine on rat atrial muscle: possible mechanisms.

Experiments were designed to evaluate the mechanisms of propofol and adenosine in rat atrial muscle. Atria were suspended in the isolated organ bath system for isometric tension recording and response to propofol and adenosine were tested in the absence and presence of glibenclamide, N(G)-nitro-arginine-methyl-ester (l-NAME), tetraethylammonium (TEA) and 8-phenyltheophylline (8-PT). The inotropic effect of propofol was elicited by TEA and glibenclamide. In contrast, l-NAME and 8-PT has no effect on the propofol-induced inhibition of atria. Furthermore, atria exhibited a diminished sensitivity to the adenosine-induced negative inotropic effect in the presence of the K(ATP)channel inhibitor glibenclamide, but not the non-specific K(+)channel inhibitor TEA. The adenosine A(1)receptor antagonist 8-PT decreased the responsiveness of adenosine-induced inhibition of atrial muscle. We propose that propofol-induced inotropy is generally mediated by K(+)channels, whereas adenosine-induced inotropy is partially mediated by K(+)channels. Both propofol- and adenosine-induced inotropy were not mediated by nitric oxide release. Our study provides further evidence that there was no contribution of adenosine in the propofol-induced inotropy.

Adenosine↗
PubMed2000

Impaired endothelium-dependent and neurogenic relaxation of corpus cavernosum from diabetic rats: improvement with L-arginine.

This study describes the relaxant response to acetylcholine, electrical field stimulation and sodium nitroprusside after contraction by phenylephrine (10(-5) M) in corpus cavernosum from control and diabetic rats. The response to acetylcholine (10(-9)-10(-3) M) and electrical field stimulation (0.5-64 Hz) is decreased and can be restored by the addition of nitric oxide synthetase substrate, L-arginine(10(-5) M). The response to sodium nitroprusside is not changed in diabetic rats compared to control rats. NADPH-diaphorase staining was enhanced in a diabetic preparation compared to control preparations. The findings suggest a role for the depletion of L-arginine in diabetes mellitus. The enhanced NADPH-diaphorase staining may be due to a deficiency of NOS substrate L-arginine in the endothelium and nerves of diabetic tissues.

Acetylcholine↗
PubMed2000

Altered relaxant responses to adenosine and adenosine 5'-triphosphate in the corpus cavernosum from men and rats with diabetes.

The present study was aimed at investigating the effects of diabetes on the cavernosal smooth muscle relaxations mediated by adenosine and adenosine triphosphate (ATP) in tissues obtained from men and rats. Adenosine- and ATP-induced relaxant responses showed an enhanced sensitivity with an unaltered effectiveness in diabetic men. Adenosine-elicited relaxation in diabetic rat corporeal tissues exhibited enhanced effectiveness with unaltered sensitivity, whereas ATP-induced relaxations were decreased in diabetic animals when compared to control animals. Tetraethylammonium pretreatment, but not glibenclamide, L-NAME and 8-phenyltheophylline, normalized enhanced apparent affinity to adenosine in tissue from diabetic men and effectiveness (E(max)) to adenosine in diabetic rats. These results suggest that adenosine-elicited relaxation in diabetes is controlled at the receptor level events including K(+) channels in men whereas in rats postreceptor-related events including K(+) channels control the adenosine-induced relaxation. These relaxations to adenosine and ATP in men and rats with and without diabetes may be nitric oxide-independent mechanisms. Our results also suggest that ATP-induced relaxation did not involve K(ATP) channels and Ca-activated K(+) channels.

Adenosine↗
PubMed2000

Antioxidants and lipid peroxidation levels of blood and cervical mucus in cows in relation to pregnancy.

Levels of vitamins A and E, beta carotene and lipid peroxidation product (TBARS) were determined in plasma and cervical mucus of 32 cows. Red blood cell (RBC) reduced glutathione (GSH) and RBC glutathione peroxidase (GSH-Px) activity as well as vitamin C plasma levels were measured. After taking cervical mucus and blood samples the animals were inseminated artificially. Three month later pregnant (n = 20) and non pregnant (n = 12) cattle were determined. Correlations between investigated parameters and pregnancy rate were performed. In blood plasma, a significant correlation was observed between vitamin A and beta carotene (P < 0.001) as well as vitamin E (P < 0.05). There was a significant (P < 0.001) correlation in TBARS values of plasma and cervical mucus. However, none of the investigated parameters showed a significant difference between pregnant and non pregnant cows. In conclusion, we did not find any difference and correlation between pregnant and nonpregnant animals concerning the investigated antioxidants. A positive correlation was observed between lipid peroxidation levels of plasma and cervical mucus. Our work provides basic informations about antioxidative parameters under physiological conditions. Further studies should investigate possible correlation between disturbed fertility and antioxidative status of plasma and cervical mucus in clinically healthy cows.

Animals↗
PubMed1999

Fractures due to hypocalcemic convulsion.

We report on two cases of patients in whom hypocalcemic seizures during hemodialysis led to right scapular body fracture in one and bilateral femoral neck fractures in the other.

Adult↗
PubMed1997

Effects of adenosine and isoprenaline in left atria from both neonatal and middle-aged noninsulin-dependent diabetic rat models.

1. This study examined the ability of atria from neonatal and middle-aged noninsulin-dependent diabetic rat models to respond to both adenosine and isoprenaline. 2. Cumulative additions of adenosine (1-1000 microM) produced concentration-dependent decreases in the force of contraction of rat atria that were unchanged in neonatal diabetic animals. Although direct inotropic responses to adenosine were unchanged, atria from neonatal diabetic animals exhibited an increase in maximum response to adenosine-induced antiadrenergic effect. 3. Atria from middle-aged noninsulin-dependent diabetic rats exhibited a supersensitivity to the direct inotropic effect of adenosine compared with atria from age-matched control rats. The middle-aged, noninsulin-dependent diabetic state did not alter the maximum response of atria to adenosine-induced antiadrenergic effect. 4. A comparison was made between middle-aged (10-month-old) controls and young (4-month-old) controls. Atria from middle-aged control animals exhibited a lower sensitivity and responsiveness to the direct inotropic effect of adenosine compared with those from young controls. 5. Cumulative additions of isoprenaline (10(-9)-10(-6) M) produced concentration-dependent increases in inotropy that were unchanged in atria from either neonatal or middle-aged noninsulin-dependent diabetic rats. 6. These results show that neonatal and middle-aged noninsulin-dependent diabetes and age-related factors lead to significant changes in atrial reactivity to the adenosine-induced stimulation in the absence and presence of isoprenaline. However; isoprenaline-induced positive inotropic response cannot change in each diabetic heart to an apparent extent.

Adenosine↗
PubMed1997

Increased responses to adenosine in isolated left atria from streptozotocin-diabetic rats: evidence for the involvement of hypothyroidism.

Direct and indirect (antiadrenergic) inotropic effects of adenosine in the isolated left atrial preparations from streptozotocin-induced diabetic rats were examined by comparing with those from propylthiouracil-induced hypothyroid rats. Experimental diabetes was induced by a single i.v. injection of streptozotocin (45 mg/kg). Subsets of diabetic rats were treated daily with either insulin (6-8 units/kg) or triiodothyronine (T3; 8-10 micrograms/kg). After 10 weeks, negative inotropic and antiadrenergic effects of adenosine were assessed in the atria from nondiabetic, diabetic, insulin- or T3-treated diabetic and hypothyroid rats. Diabetic rats exhibited a significant increase in negative inotropic and antiadrenergic effects of adenosine, as well as signs of hypothyroidism such as decreased thyroid hormone levels. The same changes in the adenosine effects also were noticed in the hypothyroid rats. In our study, the influence of T3 treatment on the hyperreactivity of diabetic rat atria to adenosine also was examined by comparing with that of insulin treatment. Both insulin and T3 treatments restored the hyperreactivity to adenosine, with the exception of adenosine receptor affinity (pD2 value) calculated for the negative inotropic effect of adenosine. These findings suggest that thyroid hormone deficiency is likely to be involved in the inotropic and antiadrenergic effects of adenosine on the left atria from rats with experimental diabetes for 10 weeks.

Adenosine↗
PubMed1997

Effects of adenosine 5'-triphosphate, adenosine and acetylcholine in urinary bladder and colon muscles from streptozotocin diabetic rats.

Bladder dysfunction and gastrointestinal disorders are common complications of diabetes mellitus and are attributed in part to peripheral neuropathy. Little is known of the mechanisms responsible for the bladder dysfunction and abnormality of the gastrointestinal tract. The effects of experimental diabetes on responses to adenosine, adenosine 5'-triphosphate (ATP) and acetylcholine (ACh) in rat bladder and colon were investigated 1 week and 8 weeks after i.v. injection of streptozotocin. Bladders from 8 week diabetic rats, but not from 1 week, were significantly larger than those from age matched controls. Relaxant and contractile responses of strips obtained from bladder body to these agonists were altered by diabetes. Relaxant responses to adenosine and ATP were also enhanced by diabetes. While maximum response and sensitivity to ATP relaxant effect were equivalent in 1 and 8 week diabetic rats as compared to age matched controls, both maximum responses to relaxant effect of adenosine and to contractile effect of ACh were reduced in colon preparations obtained from 8 week, but not from 1 week diabetic animals. The results suggest that changes in urinary bladder and colon smooth muscle function occur in diabetic rats and may contribute to the bladder dysfunction and colonic disorders seen in diabetes mellitus.

Acetylcholine↗