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Biomedical subjects

S Yildirim

Publications and source records attributed to S Yildirim.

At least 73 records · Page 4Linked to original sources
PubMed1999

Effects of chronic unilateral internal pudendal arterial occlusion on reactivity of isolated corpus cavernosum strips from rabbits.

An animal model was developed to elucidate the effect of chronic obstruction of the internal pudendal artery on the responsiveness of the corpus cavernosum. In male albino rabbits, the internal pudendal artery was chronically ligated unilaterally with a silk tie and the occlusion was maintained for 1 month. The control group was sham-operated. The reactivity of corpus cavernosum tissue from the ligated animals and the control animals was studied in organ chambers. Unilateral chronic ligation of the internal pudendal artery caused an impaired contractile response to alpha-adrenoceptor stimulation with decreased Em and pD2 values and an impaired relaxant response to electrical field stimulation but resulted in a marked increase in the endothelium-dependent relaxant response to carbachol with an increased pD2 value. However chronic obstruction of the pudendal artery had no effect on adenosine-, papaverine- and sodium nitroprusside-induced relaxant responses, and there was no change in agonist potency. These data indicate that altered penile hemodynamics have an effect on the reactivity of the corpus cavernosum and may contribute to the etiology of impotence.

Adenosine↗
PubMed1999

A comparison of the sperm mixed-agglutination reaction test with the peroxidase-labelled protein A test for detecting antisperm antibodies in infertile men with varicocele.

OBJECTIVE: To compare the sperm mixed-agglutination reaction (sMAR) with the peroxidase-labelled protein A method (POPA) in infertile patients with varicocele. PATIENTS, SUBJECTS AND METHODS: The study comprised 30 men with a history of varicocele-associated infertility and 30 fertile men (control group). Antisperm antibodies against spermatozoa in the semen and against progenitor spermatozoa in testicular tissue were detected using the two methods. RESULTS: The tests were positive in 15 (50%) of patients with both the sMAR and the POPA methods, while no autoantibodies were detected in the control group. There were no significant differences between the methods. The sensitivity and specificity of both tests was approximately 93%, with no significant difference between them (P>0. 05). CONCLUSION: Both methods may be used for detecting sperm autoantibodies in infertile patients with varicocele.

Agglutination Tests↗
PubMed1999

Corporal reactivity to adenosine and prostaglandin E1 in alloxan-induced diabetic rabbit corpus cavernosum, and the effect of insulin therapy.

OBJECTIVE: To investigate the changes in corporal reactivity to adenosine and prostaglandin E1 (PGE1 ) in corpus cavernosal strips from alloxan-induced diabetic rabbits and to determine the effects of insulin therapy. MATERIALS AND METHODS: Twenty-four New Zealand white rabbits were studied in three equal groups: group 1, control; group 2, diabetes induced by the administration of alloxan hydrochloride intravenously; group 3, as group 2 but with insulin administered after the induction of diabetes. At the end of 8 weeks, the reactivity of corpus cavernosal strips from the animals was assessed in organ chambers. RESULTS: The relaxation responses of corpus cavernosal strips to adenosine were similar in all groups, but the response to PGE1 was impaired in groups 2 and 3 compared with that in controls. CONCLUSION: If vasoactive drugs are to be used for the diagnosis or treatment of diabetic erectile impotence, direct-acting vasodilators, e.g. adenosine, must be used. In alloxan-induced diabetes, the corporal reactivity to PGE1 was impaired and insulin therapy did not restore the relaxation responses.

Adenosine↗
PubMed1999

The effects of long-term oral administration of L-arginine on the erectile response of rabbits with alloxan-induced diabetes.

OBJECTIVE: To investigate the effects of the long-term oral administration of L-arginine on the impaired neurogenic and endothelium-dependent relaxation responses of corpus cavernosum smooth muscle from alloxan-induced diabetic rabbits. MATERIALS AND METHODS: Thirty-two New Zealand white rabbits were used in four groups of eight each. In group 1, the rabbits received no treatment after the induction of diabetes with alloxan hydrochloride given intravenously; in group 2, L-arginine (1 mg/mL) was administered orally after the induction of diabetes; in group 3, 6 U/day of insulin was injected subcutaneously; group 4 was maintained with no treatment (as litter-mate controls) for 8 weeks. Thereafter, the rabbits were killed by exsanguination and the penis removed en bloc. The reactivity of corpus cavernosum strips from the penis was then assessed in organ chambers. RESULTS: Relaxation and contraction responses of corpus cavernosum strips to sodium nitroprusside and potassium chloride, respectively, were similar in all groups. Relaxation responses of corpus cavernosum strips elicited by electrical field stimulation and carbachol from rabbits in group 1 were less than in controls; the responses to carbachol were not significantly impaired in group 2 and 3, whereas responses to electrical field stimulation were impaired in both groups when compared with the control group. CONCLUSION: The impairment of endothelium-dependent and nerve-mediated relaxation by diabetes appears to involve an alteration in nitric oxide/cyclic GMP pathway. Administration of oral L-arginine increased endothelium-dependent relaxation, probably through activating nitric oxide synthase. Additionally, decreasing elevated blood glucose concentration and advanced glycosylation products by insulin treatment protected endothelium-dependent relaxation, whereas neither L-arginine nor insulin treatment restored impaired neurogenic relaxation.

Administration, Oral↗
PubMed1998

Effect of additional testosterone on purinergic responses in isolated rabbit corpus cavernosum strips.

Recently, it has been demonstrated that the endothelium of corpus cavernosum (CC) plays an important role on smooth muscle relaxation, which is crucial to initiate and maintain erection. We investigated the effect of long-lasting additional testosterone propionate (TP) therapy on endothelium-dependent and -independent relaxations of isolated rabbit CC. Isolated CC strips were mounted in organ baths and isometric tension was recorded. Addition of a specific inhibitor of nitric oxide synthesis, NG-nitro-L-arginin methyl ester (L-NAME), into the organ bath had no effect on the relaxation responses to adenosine (ADO), adenosine 5'-triphosphate (ATP) and sodium nitroprusside (SNP) in isolated CC strips precontracted with phenylepherine, but completely inhibited relaxation responses produced by ADP. Adenosine and adenine nucleotides relaxed the phenylepherine-induced contractile response in control strips with the potency order: ADO (62.8 +/- 3.2%) > ATP (37.1 +/- 5.2%) > ADP (25.8 +/- 2.5%). The relaxation responses to ADO, ATP and SNP in isolated rabbit CC strips were not significantly altered by additional TP therapy. The relaxation responses produced by ADP were significantly enhanced following 1 and 2 months TP therapy as compared with controls. However, in the group treated with TP for 2 months followed by a 2 months drug-free period, relaxation responses were significantly reduced compared to 1 and 2 months treatment groups, and approached control values. Increased relaxation responses to ADP following 1 and 2 months additional TP therapy may be a result of increased endothelial purinergic receptor density, or it may be due to stimulation and/or release of endothelial nitric oxide (NO) by TP.

Adenosine↗
PubMed1998

Tissue and concentration-dependent effects of sodium selenite on muscle contraction.

In this study, we demonstrated that sodium selenite with high doses (> or = 10(-3) M) were potent in inducing a contracture type effect on heart and smooth muscles. Selenite (Se), at a concentration of 10(-3) M, caused a contracture effect in heart preparations. Also, low Se concentrations did not have any significant effect. Although low concentrations of Se (> or = 10(-5) M) had a biphasic effects on acetylcholine (ACh) induced and spontaneous ileum contractions, 10(-3) M selenite enhanced once more a contracture effect similar to that of the heart preparations. Replacing Ca2+ concentration of the bathing solution by twofold Ca2+ or Ca2+-free did not change the effects of selenite (10(-5) M) on contractility of ileum preparations. In vascular smooth muscle, low concentration of selenite (< 10(-4)) had no significant effects on KCl, and phenylephrine-induced contractions and acetylcholine-induced endothelium-dependent relaxations of isolated rabbit aorta. However, the contractions induced by phenylephrine and the relaxations induced by acetylcholine in rabbit aorta were depressed significantly by high concentration of selenite (10(-3) M). The results obtained by selenite exposure from these three different types of tissue preparations first suggest that the high concentration of selenite exposure induces some alterations in the functions of muscles and endothelium in a tissue- and dose-dependent manner. Second, this observed irreversible type of dysfunction of tissues induced by 10(-3) M selenite is not directly dependent on the Ca2+ entrance into the cytosol, but might be induced by the increase of intracellular Ca2+ with the disturbance of Ca2+ regulation.

Acetylcholine↗
PubMed1998

Possible mechanism of high calcium-induced relaxation of rabbit thoracic aorta.

1. The present study examined the effects of various agents on high calcium-induced relaxation of the rabbit thoracic aorta precontracted by phenylephrine (0.1 microM) or KCl (30 mM). 2. The vascular smooth muscle relaxation caused by high calcium was not changed in the presence of endothelium, glibenclamide (3 microM), TEA (5 mM), verapamil (1 microM), lidocaine (0.1 mM) and vanadate (0.1 mM). 3. In the presence of ouabain (0.1 mM) or potassium-free medium, high calcium-induced relaxation was completely abolished. 4. When rings were precontracted by high concentrations of phenylephrine (1 microM, 10 microM) and KCl (30 mM, 45 mM, 60 mM), calcium-induced relaxation was gradually decreased. 5. A low concentration of calcium ionophore A-23187 (0.1 microM) did not change calcium-induced relaxation, but A-23187 at a high concentration (1 microM) depressed this relaxation. 6. These results suggest that Na-K-ATPase activation could be responsible for high calcium-induced relaxation.

Animals↗
PubMed1998

Tolerance to isosorbide dinitrate in isolated strips of rabbit corpus cavernosum.

The aim of this study was to investigate whether prolonged exposure to a high concentration of isosorbide dinitrate (ISDN) would result in tolerance being developed against its relaxant activity in strips of corpus cavernosum, pre-contracted by phenylephrine. Under these conditions, relaxation induced by ISDN was found to be significantly reduced. Strips made tolerant to ISDN remained fully responsive to sodium nitroprusside and papaverine. Electrical field stimulation evoked relaxations which were persistent in the presence of tolerance-inducing conditions. These results indicate that desensitization of guanylate cyclase activity is not likely to be the operating mechanism for nitrate tolerance. We suggest that tolerance may result from the impairment of biotransformation of ISDN in rabbit cavernosal smooth muscle.

Animals↗
PubMed1998

Impaired contraction and relaxation in the aorta of streptozotocin-diabetic rats.

It is known that diabetes mellitus alters the vascular responsiveness to several vasoconstrictors and vasodilators. Endothelium-derived nitric oxide is a potent endogenous nitrovasodilator, and endothelin-1 (ET-1) is a potent endothelium-derived vasoconstrictor substance. They play a major role in the modulation of vascular tone. Selective impairment of endothelium-dependent relaxation and impaired vasoconstriction in response to ET-1 could result in vascular disorders. The purpose of our study was to determine whether vascular responses to ET-1 and endothelium-dependent relaxing substances are impaired in rats with streptozotocin-induced diabetes of 2 weeks duration. Endothelium-dependent relaxations produced by carbachol and ATP in aortic rings precontracted with phenylephrine were significantly attenuated in rings from diabetic rats, but the endothelium-independent relaxations produced by sodium nitroprusside and adenosine in diabetic preparations were not changed when compared to the corresponding controls. The ET-1-induced contractions were significantly attenuated with no change in agonist potency (pD2 value) in aortae with and without endothelium obtained from diabetic rats when compared to those from controls. Mechanical removal of the endothelium did not significantly change ET-1 responses of aortae from either diabetic or control rats compared with responses of aortae with intact endothelium. These results suggest that, in this diabetic model, the contractile responsiveness of thoracic aortic muscles and the endothelial functions are significantly altered during 2 weeks of diabetes.

Adenosine↗
PubMed1998

Long-term follow-up of 102 living kidney donors.

This study evaluated 102 randomly selected living-related kidney donors who were operated between November 1975 and December 1996 after a mean follow-up period of 10.2 years (range 8 months to 22 years). The donor male:female ratio was 45:57, and mean age was 41.0 years (range 21 to 65 years). The average preoperative and last follow-up blood creatinine levels were 73.37 micromol/l (range 44.2-106.8 micromol/l) and 78.67 micromol/l (range 8.84-318.2 micromol/l), respectively (p:NS), and the corresponding average creatinine clearance values were 108.4 ml/min (range 100-130 ml/min) and 96.8 ml/min (range 27 to 125 ml/min) (p: NS). Four donors had 24-hour urine protein excretion above 0.1 gram (2 G, 0.7 G, 0.2 G, and 0.14 G, specifically). The donors' mean systolic blood pressures before, and after the operation on the last follow-up were 131.7 +/- 21.2 mmHg and 139.6 +/- 20.9 mmHg, respectively (p:NS). Nine donors (8.8%) developed hypertension which required anti-hypertensive treatment. The mean age of the hypertensive group was 48.0 years (range 30 to 65 years), whereas that for the nonhypertensive group was 39.4 years (range 18 to 76 years) (p <0.02). Only one donor (0.9%), a 41 year-old female, was diagnosed with chronic renal disease related to pyelonephritis. These results support the utilization of living donors for kidney transplantation, an option which helps broaden a limited donor pool.

Adolescent↗
PubMed1997

Five-year results of the treatment of 23 patients with immunoproliferative small intestinal disease: a Turkish experience.

BACKGROUND: Currently, there is no agreement regarding optimal treatment strategies for immunoproliferative small intestinal disease (IPSID). In this article, the authors report the treatment outcomes of a group of 23 Turkish patients with IPSID. METHODS: Between December 1988 and July 1993, 23 consecutive patients with IPSID, including 5 with secretory type, were included in the study. Seven patients with Stage A disease (according to the criteria of Galien et al.) received tetracycline (1 g/day, orally) for a median duration of 7 months (range, 6-11 months) initially, whereas the remaining patients (9 Stage B patients and 7 Stage C patients) received combination chemotherapy (cyclophosphamide, vincristine, procarbazine, and prednisolone [COPP regimen]) followed by tetracycline at a dose of 1 g/day for 6 more months in patients with complete response (CR) after the COPP regimen. RESULTS: The median follow-up was 68 months (range, 38-89 months). As first-line therapy in Stage A patients, tetracycline yielded a 71% CR and 43% disease free survival (DFS) rate. Eleven of 16 patients (69%) with Stage B or C disease who received the COPP regimen achieved CR and only 2 patients had a recurrence (DFS rate of 56%). The 5-year overall survival (OAS) rate for the entire group was 70%, and the 5-year DFS rate for patients with CR was 75%. However, the median OAS for 3 patients with immunoblastic lymphoma was only 7 months. CONCLUSIONS: The COPP regimen, with its acceptable toxicity, appears to be a good alternative as a first-line treatment for patients with Stage B or C IPSID with low grade lymphoma whereas tetracycline appears to be the initial treatment of choice for patients with Stage A disease.

Adolescent↗
PubMed1997

Comparison of Neoral and Sandimmun for induction and maintenance immunosuppression after kidney transplantation.

We compared the mean trough level/dose (L/D) ratio, mean coefficient of variation (CV) of individual patients, and graft, patient, and rejection-free survival rates of 40 renal transplant recipients receiving Neoral (CyE) with 103 consecutive renal transplant recipients receiving Sandimmun (CyA). The mean L/D ratio on the 3rd post-transplant day (16.2 vs 11.8, P < 0.04), in the 1st week (24.6 vs 16.1; P < 0.03), and 1st month (39.1 vs 28.7; P < 0.05) were higher in the CyE group. In both groups the L/D ratio improved in proportion to the duration of time post-transplant and reached a maximum in the 3rd post-transplant month. In the early post-transplant period in particular, the number of patients achieving target levels was significantly higher, and the mean dose needed to achieve target levels lower, in the CyE group. The variation in trough levels, demonstrated by the CV, was lower in the CyE group (0.41 +/- 0.14) than in the CyA group (0.62 +/- 0.21; P < 0.005). Actuarial 1-year patient and graft survival rates in the CyE group were 100% and 96%, respectively; these were similar to the 100% and 95% in the CyA group. The 1-year rejection-free survival rate in the CyE group was 61% compared to 43% in the CyA group (P < 0.02). We conclude that it is possible to obtain higher blood trough levels at lower doses by administering CyE, particularly in the early post-transplant period. The lower variability of trough levels and the higher L/D ratio in the CyE group, which are related ti improved bioavailability of CyE, may explain the lower rejection rate among these patients. In this study, the microemulsion formulation of cyclosporin (CyE) was found to be more beneficial and cost-effective as induction and maintenance immunosuppression than the conventional formulation (CyA).

Azathioprine↗
PubMed1997

Effects of castration on adrenergic, cholinergic and nonadrenergic, noncholinergic responses of isolated corpus cavernosum from rabbit.

OBJECTIVE: To investigate the effects of castration and testosterone on the constricting effect of phenylephrine and endothelium-dependent and -independent relaxing effects of different agonists in the corpus cavernosum of male rabbits. MATERIALS AND METHODS: Twenty rabbits were castrated and 10 received testosterone replacement for 1 month after castration; 10 further rabbits underwent a sham operation and acted as controls. One month after operation the rabbits were killed and their penises excised. Strips of corpus cavernosum were used for isometric tension measurements in organ chambers; concentration-response relationships for phenylephrine, carbachol, adenosine and sodium nitroprusside were obtained by adding the reagent cumulatively to the bath. RESULTS: The phenylephrine-induced contractions were markedly lower, with no change in the pD2 values (i.e. the negative logarithm of the concentration for half-maximal response), in cavernosal strips obtained from castrated rabbits than in those from controls. Endothelium-dependent relaxation elicited by carbachol increased in the castrated group but the relaxation induced by sodium nitroprusside did not change and those elicited by adenosine were strongly depressed when compared with controls. There were no significant changes in the pD2 values of agonist-induced relaxation responses in all groups. The relaxation elicited by electrical-field stimulation at lower frequencies increased in strips from castrated rabbits but at higher frequencies were unchanged when compared with controls. Castration-induced changes in the relaxation response of cavernosal strips were significantly restored by in vivo testosterone replacement but those induced by phenylephrine were not. CONCLUSION: The lack of testosterone has an effect on the reactivity of the corpus cavernosum, indicating that testosterone has an important role in erectile function by a pre- or post-synaptic action on the corpus cavernosum.

Adenosine↗