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Biomedical subjects

A Melman

Publications and source records attributed to A Melman.

At least 19 recordsLinked to original sources
PubMed1992

Urothelial tumors of upper tract following treatment of primary bladder transitional cell carcinoma.

We studied, retrospectively, the incidence of upper tract urothelial tumors following the treatment of primary transitional cell carcinoma of the bladder in 638 patients. Subsequent tumor development was found in 20 patients (3.1%) with a mean latency interval between initial treatment of the bladder cancer and diagnosis of the upper urinary tract tumor of eighty months. We did not find a significant difference among treatment modalities on the incidence of upper tract occurrences. Other than carcinoma in situ, tumor stage was not an independent predictive variable.

Carcinoma in Situ↗
PubMed1992

Collagen alterations in the corpus cavernosum of men with sexual dysfunction.

Previous studies have noted the abundance of collagen in human erectile tissues and the association of altered collagen content with erectile dysfunction. We investigated these notions by studying the collagen characteristics of biopsies from the corpus cavernosum of men who required surgical correction of their sexual dysfunction. Histologic analysis revealed abundant collagen within the erectile tissues. With the exception of patients with Peyronie's disease and priapism, only mild alterations in collagen architecture were noted in the remainder of the patients. Biochemical quantitation confirmed the histologic study. The mean collagen content represented 47% of total protein in most patients. The proportion rose to 68% and 73% in the patients with Peyronie's disease and priapism, respectively. No statistical difference in collagen content was noted in all the patients studied. Immunohistochemistry revealed collagen types I and IV to predominate in the corpus cavernosum, with type III making up the minority. There were no qualitative changes in collagen ratios with age and disease. We conclude that though collagen is a major component of the penis, there are no changes in its histologic characteristics that can be correlated to senescence or to the etiology of erectile dysfunction.

Adult↗
PubMed1992

Gap junction-mediated intercellular diffusion of Ca2+ in cultured human corporal smooth muscle cells.

Ratio imaging using the calcium-sensitive probe fura-2 was employed to study intracellular calcium concentrations and intercellular calcium flux through gap junctions in homogeneous vascular smooth muscle cell cultures derived from the human corpora cavernosa. Microinjection techniques demonstrated that fura-2 free acid was freely diffusible through gap junctions between cultured cells. The resting intracellular calcium level in fura-2-loaded cells was 176.9 +/- 10.5. A robust increase in intracellular calcium was seen in response to both phenylephrine and the calcium ionophore A23187. Microinjection of Ca2+ into individual smooth muscle cells always resulted in significant, although temporally delayed, increases in intracellular calcium levels in adjacent cells; this intercellular calcium flux was reversibly blocked by inhibition of gap junctional communication with 2 mM heptanol. However, although microinjection of D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] into individual smooth muscle cells always produced significant increases in intracellular calcium levels in the injected cell, the intercellular spread of Ca2+ in response to Ins(1,4,5)P3 was more variable than for Ca2+ injections. These studies demonstrate that Ca2+, and perhaps Ins(1,4,5)P3 as well, can diffuse between smooth muscle cells through gap junction channels.

Alcohols↗
PubMed1992

Kinetic characteristics of alpha 1-adrenergic contractions in human corpus cavernosum smooth muscle.

Kinetic studies were conducted on the contractile response elicited by phenylephrine (PE) activation of the alpha 1-adrenergic receptor subtype in vascular smooth muscle isolated from the corpus cavernosum of impotent men. PE-induced contractions were separated into distinct phasic and tonic components, and the tonic portion was analyzed using a first-order rate equation to determine the maximal rate constant for onset of contraction (kobs max) and the maximum amplitude of the steady-state contractile response (Req max). The kobs max value in tissues from insulin-dependent diabetic patients was significantly greater than that in tissues from either noninsulin-dependent diabetics or nondiabetics. Additionally, the mean kobs max value in older patients (60-70 yr) was significantly greater than the mean kobs max value in younger patients (32-59 yr). Significant diabetes-related, but not age-related, alterations were also found in Req max. The observed changes in contractility resulted in dramatic age- and pathology-dependent alterations in the initial rate and/or magnitude of PE-induced response generation. These kinetic studies extend our previous observations at steady state and provide further evidence for heightened corporal tissue tone in the etiology of erectile dysfunction.

Aging↗
PubMed1991

Intercellular communication through gap junctions: a potential role in pharmacomechanical coupling and syncytial tissue contraction in vascular smooth muscle isolated from the human corpus cavernosum.

Kinetic and steady-state protocols were used to examine the effects of disruption of intercellular communication with heptanol, on contractile responses elicited by activation of the alpha 1-adrenergic receptor in human corporal vascular smooth muscle. For the steady-state studies, strips of corporal tissue from 19 patients were submaximally precontracted with phenylephrine (PE) and then relaxed by the cumulative addition of heptanol. Heptanol completely and reversibly relaxed all tissues studied in a concentration-dependent manner. The heptanol concentration response data were then computer fit to the general logistic equation to obtain pEC50 (negative logarithm of the concentration that elicits one-half of the maximal effect) and slope factor values, with Emax (maximal relaxation) set to 100%. The mean pEC50 and slope factor values, respectively, were 2.86 +/- 0.04 and 1.86 +/- 0.17. Furthermore, kinetic studies on corporal tissues from a subset of the patient population (11 patients) revealed that preincubation of tissues with 2 mM heptanol caused a significant decrease in both the rate and magnitude of PE-induced contractions in all tissues studied, without affecting the rate constant for onset of contraction (k(obs)). The present results on intact tissue extend our previous observations on cultured corporal cells, and support the supposition that intercellular communication through gap junctions may play an important role in the initiation, maintenance and modulation of alpha 1-adrenergic contractions in human vascular smooth muscle.

Adult↗
PubMed1991

Male fertility in cyclosporine-treated renal transplant patients.

Fertility and potential fertility were evaluated in 9 young men on cyclosporine A therapy following renal transplantation. Semen analysis was normal in most parameters in 8 patients as was testicular hormonal function. Of 4 men who had attempted to impregnate their wives 3 succeeded. Cyclosporine A does not seem to affect adversely fertility in men.

Adult↗
PubMed1991

Follow-up of patients and partners experiencing penile prosthesis malfunction and corrective surgery.

An interview study is reported involving 14 men who had experienced at least one penile prosthesis malfunction and corrective surgery. Six partners were interviewed separately. The results indicated a broad range of coping patterns in terms of fears and disappointments, but an overall outcome of six cases very satisfactory, five satisfactory despite various worries or complaints, and three unsatisfactory. The discussion emphasizes coping, doctor-patient communication, and difficulties in predicting long-term outcome in these cases.

Adaptation, Psychological↗
PubMed1991

Age-dependent alterations in the efficacy of phenylephrine-induced contractions in vascular smooth muscle isolated from the corpus cavernosum of impotent men.

Steady-state contractile responses elicited by phenylephrine activation of the alpha 1-adrenergic receptor subtype were studied in vascular smooth muscle strips isolated from the corpus cavernosum of impotent men. The dissociation constant of phenylephrine was determined by the method of partial irreversible receptor inactivation over a wide range of alpha 1-adrenergic receptor alkylation levels. Statistical analysis of mean population values revealed a significantly greater mean efficacy for phenylephrine-induced contractions in older patients (60-73 years old) than in younger patients (40-59 years old), in the absence of similar alterations in the mean phenylephrine dissociation constant (affinity). In addition, there was no significant effect of the diabetic state on the mean phenylephrine affinity or efficacy estimates. However, despite the absence of age- or pathology-dependent variations in agonist affinity, as assessed by group mean calculations, a detailed examination of all isolated tissues on an individual basis revealed that the phenylephrine affinity estimates varied over a range of almost two orders of magnitude. Furthermore, a linear regression analysis revealed a highly significant positive correlation between agonist affinity and the location of the phenylephrine concentration-response curve, which was characterized by a slope significantly less than unity. In conclusion, an increased efficacy of phenylephrine-induced contractions in vitro is consistent with the hypothesis that augmented corporal vascular smooth muscle contractility in vivo may contribute to the pathophysiology of impotence in older patients.

Adrenergic alpha-Agonists↗
PubMed1990

Penile vein ligation for corporeal incompetence: an evaluation of short-term and long-term results.

Dynamic cavernosometry and cavernosography can be used to identify patients with corporeal venous incompetence as a cause of erectile dysfunction. We reviewed our series of 16 patients with venous leakage who underwent surgical correction of the specific abnormality identified on cavernosography. Short-term and long-term results were obtained, and while at least temporary improvement was noted in 89.5% of the patients the long-term results tended to show a reversion to the preoperative status in the majority.

Erectile Dysfunction↗
PubMed1990

Followup observations of operated male-to-female transsexuals.

We performed an in-depth interview to ascertain the psychosocial and functional status in 10 of 22 male-to-female transsexuals who underwent vaginoplasty from May 1985 to December 1988. Followup from 5 to 48 months was available for 14 patients. Our patients comprised a well educated, mostly employed, law abiding group with a low incidence of drug use. Most patients were able to develop strong support systems and showed a marked decrease in suicidal tendencies postoperatively. Functionally, the majority of the patients were able to lubricate the neovagina and have painless intercourse with a potential for orgasm. The cosmetic result was judged to be good, with no patient reporting being discovered of having had a prior operation by the sexual partner. We experienced a 21% rate of vaginal stenosis with 40% of these patients fully functional after a corrective operation.

Adaptation, Psychological↗
PubMed1990

Pharmacological studies of human erectile tissue: characteristics of spontaneous contractions and alterations in alpha-adrenoceptor responsiveness with age and disease in isolated tissues.

1. The pathophysiology of impotence related to vascular smooth muscle dysfunction in the male corpus cavernosum was studied on human isolated erectile tissue (HET). Studies were conducted on 140 sections of HET obtained from 38 male patients undergoing surgery for implantation of penile prostheses to correct underlying erectile dysfunction. 2. Spontaneous myotonic oscillations were characteristic of greater than 90% of all HET preparations at 37 degrees C. These spontaneous oscillations were markedly attenuated by indomethacin, BW755C, nifedipine, removal of extracellular Ca2+, or lower temperatures (less than or equal to 32 degrees C), but were not sensitive to inhibition by atropine, phentolamine or tetrodotoxin. Our data suggest that the oscillations may, at least in part, result from the generation and/or release of a stable cyclo-oxygenase product and a consequent increase in transmembrane Ca2+ influx. 3. The phenylephrine-induced contractions in HET may be reliably assayed up to 24 h after surgical removal, without significant alterations in the EC50, maximum response (Emax) or slope index of the steady-state concentration-response curve to phenylephrine. 4. The competitive and surmountable nature of the antagonism of phenylephrine-induced contractions by prazosin and yohimbine allowed calculation of antagonist dissociation constants. The calculated pKb values for prazosin and yohimbine, respectively, were 9.47 +/- 0.49 and 5.54 +/- 0.22. The rank order of agonist potency in HET was: noradrenaline = phenylephrine much greater than clonidine. These data indicate the presence of a population of membrane receptors that are predominantly of the alpha 1-adrenoceptor subtype. 5. The entire patient population was stratified on a decennial basis into five age groups, and each age group was subsequently subdivided into diabetic and nondiabetic diagnostic categories. With respect to the steady-state phenylephrine concentration-response curves, a Winer two-factor analysis of variance revealed a significant effect of age on the calculated pEC50 value, as well as a significant age-diagnosis interaction. A post hoc statistical analysis for unpaired samples yielded significant differences between pEC50 values for diabetic and nondiabetic patients in age groups 41-50 and 61-70 years. In addition, a Winer two-factor analysis of variance also detected a significant effect of age on the calculated E.., value. 6. In conclusion, our studies demonstrate that spontaneous contractions in HET are likely to be mediated by the generation and release of a stable cyclo-oxygenase product. Furthermore, the results of both agonist and antagonist studies are consistent with the presence of a homogeneous alpha x-adrenoceptor population. Lastly, the responsiveness of isolated HET to phenylephrine was shown to be altered by both age and disease.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1988

Instability and rotation of silver silicone penile prosthesis.

Four cases of a similar complication in patients who have had the Jonas silver silicone prosthesis implanted are reported. The patients complain of instability and rotation of the prosthesis to a position that stands out from the body, no matter what the initial position of the prosthesis. The rotation causes difficulty with coitus. The explanation is one of a manufacturing and not a surgical defect.

Adult↗
PubMed1988

Evaluation of first 406 patients in urology department based Center for Male Sexual Dysfunction.

Four hundred six patients with a complaint of erectile dysfunction were evaluated in a urology department based Male Sexual Dysfunction Center. Results of physical examination, medical and psychosexual history, nocturnal penile tumescence (NPT), penile blood pressure, visual sexual stimulation, hormonal screen, and partner interview were used in establishing the final diagnosis. A summary of the final diagnoses is as follows: organic impotence 117 (28.8%), psychogenic impotence 161 (39.7%), combined factors 102 (25.1%), and dysfunction of unknown origin 26 (6.4%). Data analysis confirms that to establish a diagnosis of organic erectile failure multiple objective measurements in combination with patient and partner history are necessary.

Aged↗
PubMed1988

Evaluation of patients and partners 1 to 4 years after penile prosthesis surgery.

One to 4 years after penile prosthesis implantation 52 men and 22 partners were interviewed personally. All except 4 patients were having intercourse on a regular basis. A quarter of the patients reported restriction in intercourse positions, possibly because of a smaller penis postoperatively, and 15 per cent reported decreased orgasm intensity. Six men had an undiagnosed prosthesis malfunction or they used an inadequate pumping technique, suggesting that prosthesis patients should be followed on a continuing basis. The 52 men had experienced 10 malfunctions with the prosthesis. Partial erections were reported by 69 per cent of the patients but this could be confirmed in only 1 of 10 with visual sexual stimulation testing. It is suggested that differences between prosthesis models are more a result of psychological, relationship and health factors than mechanical factors. Of the patients 79 per cent would undergo the operation again but only 59 per cent of the partners had no hesitations. The longer the postoperative period the more hesitations. A satisfaction score was used to measure patient satisfaction.

Coitus↗
PubMed1988

Evaluation and management of erectile dysfunction.

The man who seeks treatment for impotence typically has a sense of inadequacy that extends beyond sexual satisfaction to his business and personal relationships. Although no magic potion is available, current medical technology allows the surgeon to accommodate each patient who seeks treatment, guaranteeing sufficient penile rigidity to effect coitus.

Erectile Dysfunction↗