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Biomedical subjects

V K George

Publications and source records attributed to V K George.

10 recordsLinked to original sources
PubMed1999

Effect of cocaine on testicular blood flow in rats: evaluation by percutaneous injection of xenon-133.

PURPOSE: Cocaine abuse has reached epidemic proportions in the United States. Our recent study has shown that cocaine has adverse action on spermatogenesis and fertility in male rats. The indirect action of cocaine occurs by blocking the reuptake of neurotransmitter, which causes local vasoconstriction. In this study we evaluate blood flow to the testes after subcutaneous injection of cocaine to male rats. METHODS: Male Sprague-Dawley rats were divided into two main groups. The treatment group received subcutaneous cocaine (30 mg/kg body weight) and the control animals received normal saline. Xenon-133 wash out experiments were carried out on testes at 5, 10, 15, 20, 30, 45, 60, 90 min and 4.5 hours after injection of cocaine or normal saline. Statistical analysis was done by SPSS V. 7.S for windows. P < 0.05 was considered statistically significant. RESULTS: There was a reduction in testicular blood flow after cocaine administration to male rats. This vasoconstrictor effect was most pronounced at 15 min after injection of cocaine and persisted up to 60 min. At 90 min, the early restitution of blood flow to ischemic tissue occurred. There was a significant increase in testicular blood flow in cocaine-treated groups than in the control group during restitution phases at 90 min. At 4.5 hours, there was no difference in blood flow in both groups. CONCLUSION: This study demonstrates that cocaine, when given subcutaneously at a 30 mg/kg body weight dose, results in prolonged vasoconstriction of the blood vessels to the testes. Adverse effects of cocaine on the testes may be in part due to ischemic and postischemic reperfusion injury to the organ.

Administration, Cutaneous↗
PubMed1997

Characterization of cocaine binding sites in the rat testes.

PURPOSE: An estimated 29 million individuals use cocaine in the United States. Studies have shown a high affinity for dose dependent binding of cocaine in the testes. Recent work done in our laboratory has shown that chronic administration of cocaine to male rats has an adverse effect on fertility and spermatogenesis by producing extensive morphological changes in the testes, leading to reduction in sperm production. As a first step toward understanding this process, we characterized and identified the pharmacological properties of [3H]cocaine binding sites in the testes. MATERIALS AND METHODS: Crude membranes from the testes were prepared from 35 days old male Sprague-Dawley rats. [3H]cocaine binding was measured by using the method of Madras et al. (1989) with modifications. The data from saturation binding assays were analyzed by Inplot (GraphPad Software, San Diego, CA) to determine the Kd and Bmax. RESULTS: Specific binding of [3H]cocaine was linearly dependent on membrane protein concentrations ranging from 0.2 to 8 mg./ml. The pooled data from three independent experiments revealed a mean affinity of 36 +/- 2.0 nM and Bmax of 1.84 +/- 0.13 pmol/mg. The present study demonstrates that testicular tissue has receptor protein that binds [3H]cocaine saturably and specifically. Competition displacement experiments revealed a shallow displacement curve for (-)cocaine and Win 35,428 with r2 = 0.96, indicative of multiple binding components. Computer analysis confirmed that a two component binding model was preferred statistically over a one component model in all three experiments (p < 0.001). CONCLUSION: The results from these studies suggest that the testicular tissue contains a protein that binds [3H]cocaine in a saturable and specific manner. It has a different sensitivity from the [3H]cocaine binding protein in the brain and placenta. Further clarification of the relationship between cocaine and its recognition site is necessary to understand the mechanism of testicular damage after cocaine exposure.

Animals↗
PubMed1997

Histopathological changes in the testes of prepubertal male rats after chronic administration of cocaine.

PURPOSE: This study was conducted to evaluate histopathologic findings in the testes of prepubertal male rats after long-term cocaine exposure. METHODS: At 25 days of age, male Sprague-Dawley rats were administered cocaine hydrochloride daily (15 mg/kg body weight corresponding to an average single dose for a heavy cocaine user). The treatment was continued for 100 days when all the rats were sacrificed. Morphological analysis of the testes were assessed by qualitative and quantitative histological means. RESULTS: In all the groups, a minimum of 5 to 10 representative seminiferous tubules were examined. The mean diameter of the seminiferous tubules was less in the treated group than in their respective controls (p < 0.05). The thickness of the germinal epithelium was much reduced in the cocaine-treated groups when compared with their controls (p < 0.05). The number of degenerating germ cells was greater in the treated group than in the controls. There was evidence of failure to release the mature spermatids in the treated groups. There was no evidence of sloughed Sertoli cells or germ cells in the tubular lumen or the epididymis. CONCLUSION: There were distinct histopathological changes noted after chronic administration of cocaine. These changes are characteristic of toxic effects on the testes, but the exact mechanism is not clear. Further studies are underway in our laboratory to delineate the exact mechanism of action by cocaine on the testes.

Animals↗
PubMed1996

The management of extensive penile fibrosis: a new technique of 'minimal scar-tissue excision'.

OBJECTIVE: To evaluate the results of excising minimal scar tissue in patients undergoing insertion of a penile prosthesis for extensive corporal fibrosis. PATIENTS AND METHODS: Twelve patients (mean age 58 years, range 44-73) with extensive corporal fibrosis who underwent the insertion of a penile prosthesis were evaluated. Eleven patients had a defect of varying extent after the insertion of the penile prosthesis, and a polytetrafluoroethylene graft was used to cover the area. RESULTS: All 12 patients tolerated the procedure well and currently have a functioning penile implant. CONCLUSIONS: Minimal excision of scar tissue provided better results and fewer complications when compared to other studies which used extensive excision.

Adult↗
PubMed1996

Effects of long-term cocaine exposure on spermatogenesis and fertility in peripubertal male rats.

PURPOSE: This study was conducted to investigate the effects of long-term administration of cocaine on spermatogenesis and fertility in adult male rats. MATERIALS AND METHODS: Thirty-day-old male Sprague-Dawley rats were given cocaine hydrochloride (15 mg./kg. body weight, corresponding to an average single dose for a heavy cocaine user) either daily or twice weekly (weekend group, cocaine given on Saturday and Sunday) and mated with pregnancy-proven female rats after 100 and 150 days of exposure to the drug. Pregnancy rates and litter birth weights were evaluated. Serum testosterone, follicle stimulating hormone and luteinizing hormone levels were measured in all adult rats. Morphologic analysis of the testis entailed the evaluation of quantitative and qualitative histologic parameters to assess the effect of cocaine on various stages of spermatogenesis. RESULTS: After 100 days of treatment, the rats receiving daily cocaine had a pregnancy rate of only 33% versus 86% for the controls (p < 0.05). In rats exposed to cocaine for 150 days the pregnancy rate was 50% compared with 100% for controls (p < 0.05). The birth weights of offspring from the group receiving daily cocaine was 10% less than that of controls (p < 0.05). The weight of the testis and epididymis was not affected by cocaine exposure. Morphometric analysis showed significant differences between the cocaine-treated groups (both the daily cocaine and twice weekly cocaine groups) and their respective controls. The mean diameter of seminiferous tubules in the daily and twice weekly cocaine groups was reduced when compared with their respective controls. These differences between treated groups and their controls were statistically significant (p < 0.05). Similarly the thickness of the germinal epithelium was less in the cocaine-treated groups than in the controls (p < 0.05). Degenerating cells were more numerous in both daily and twice weekly cocaine groups than the controls. Furthermore, the number of step VII spermatids was reduced in both daily and twice weekly cocaine groups, a difference that was statistically significant (p < 0.05). CONCLUSION: Our findings demonstrate that chronic administration of cocaine to peripubertal male rats has a profound effect on their testicular function. Even with twice weekly administration there was a significant adverse effect on spermatogenesis although this was not manifested by diminished fertility in this group. These findings confirm that chronic administration of cocaine to male rats can have a deleterious effect on spermatogenesis and fertility.

Animals↗
PubMed1995

Follow-up with Mentor two-piece inflatable penile prosthesis.

Between October, 1987 and June, 1993, we implanted 50 Mentor two-piece inflatable penile prostheses with a mean follow-up of 52.18 months (6-72 months). In 7 pts (14%), the implants were removed for various reasons. One pt (2%) had total fluid leak due to breakage of the tube at its junction with the cylinder. One implant (2%) was replaced due to loss of rigidity. Two implants (4%) were removed due to infection and later replaced with semirigid prostheses. Three pts (6%) had pump erosion. There was loss of rigidity in seven implants (14%), which appears to be due to stretching of the tunica albuginea from repeated use. The limited amount of fluid in the resipump precludes compensation for the stretching, leading to loss of rigidity. The overall complication rate of 28% in this long-term series appears to be much higher than that in other reported short-term follow ups. Thirty-six pts (72%) are fully satisfied with the device and 7 pts (14%) are partially satisfied, with an overall satisfaction rate of 86%. In our series, 46/50 (92%) pts have functioning prostheses at the time of review.

Adult↗
PubMed1992

The effect of ranitidine on urine mucus concentration in patients with enterocystoplasty.

We describe the effect of ranitidine in reducing mucus in urine in 8 patients with enterocystoplasty and present a simple technique for measuring the concentration of mucus in urine. After a 10-day course of ranitidine (300 mg daily in divided doses) the concentration of mucus had fallen significantly from an initial level of 1.38 +/- 0.18 to 0.39 +/- 0.04 mg/ml.

Female↗
PubMed1991

Clam ileocystoplasty.

Clam enterocystoplasty has been used successfully in the treatment of refractory urge incontinence. We report 31 patients who underwent ileocystoplasty between 1982 and 1989. The majority of patients were pleased with the outcome of the operation. The main post-operative complication was voiding dysfunction due to relative bladder outflow obstruction. Urinary tract infection and mucus production were significant long-term problems.

Adult↗