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Biomedical subjects

R D McClure

Publications and source records attributed to R D McClure.

At least 19 recordsLinked to original sources
PubMed2001

Androgen deficiency and the aging male: new urologic perspectives.

Among the most prominent health care issues of the 21st century are those relating to aging. Indeed, the elderly represent the fastest growing segment of our population. Typically, a urology practice includes a significant number of elderly males, providing the physician with both a challenge and an opportunity. Androgen deficiency in the aging male, with its detrimental effects on bone, muscle and body composition, sexual function, and psychological well-being, is an area of increasing interest in both the lay press and the medical community. The urologist must understand the pathophysiology of androgen deficiency in the male, recognize and investigate the subtle signs and symptoms of hypogonadism, determine the appropriateness of treatment, and offer informed options to the patient. Health care professionals have a responsibility to make "healthy" aging a priority.

Aged↗
PubMed1996

Back-pressure testing to prevent autoinflation of penile prosthetic devices.

Autoinflation of a penile prosthetic device can be a frustrating experience for the patient and surgeon alike. Although there are many causes of autoinflation, elevated reservoir pressure at the time of surgical placement is one of the more common etiologies. We describe a simple, quick technique to quantitate reservoir pressures and volume, preventing pressures that could lead to autoinflation.

Humans↗
PubMed1996

Endocrine screening for sexual dysfunction using free testosterone determinations.

PURPOSE: Controversy exists concerning the need for routine endocrine screening in impotent men. Debate also continues as to what hormonal studies are necessary, the role of the free fraction of testosterone and whether a history of decreased libido or testicular atrophy can predict these endocrinopathies. MATERIALS AND METHODS: We reviewed 508 consecutive men who presented with sexual dysfunction within a 22-month period. Testosterone data were available for 268 patients (53%) and prolactin data were available for 170 (33%). RESULTS: Hypogonadism, defined as 2 abnormal total testosterone levels, was found in 42 of our 268 patients (15.6%). A history of decreased libido by patient questionnaire and/or testicular atrophy on physical examination could not predict these cases. A normal free fraction of testosterone saved further unnecessary endocrine evaluation in 50% of patients with hypogonadism. Hypoprolactinemia was noted in 3 of 170 patients (1.8%). CONCLUSIONS: Routine endocrine screening remains a necessary part of the evaluation for sexual dysfunction. A history of decreased libido and/or testicular atrophy on physical examination cannot predict hypogonadism. Measurement of free fraction of testosterone will further lessen unnecessary endocrine evaluations by 50% and should become standard practice in screening for hypogonadism. Prolactin levels are necessary only in patients with hypogonadism and/or a history of decreased libido.

Adult↗
PubMed1995

Timing of penile color flow duplex ultrasonography using a triple drug mixture.

Duplex ultrasonography is an accepted method to assess noninvasively arterial inflow to the penis. Optimal pharmacological agents as well as timing of the scan and stimulation during the scan continue to be debated. In an effort to achieve a more complete smooth muscle relaxation and capture what we perceived was a wide variation in interval to maximum arterial velocity, we revised our duplex protocol in January 1991. We report on 280 consecutive patients evaluated in this manner. Patients received 0.25 or 0.5 cc of a triple drug mixture containing 22.5 mg./cc papaverine, 0.83 mg./cc phentolamine and 8.33 micrograms/cc prostaglandin E1. Scans were performed at 0, 5, 15 and 30 minutes after injection in all patients. Any patient not having a full erection at 15 minutes performed private self-stimulation while in the standing position for at least 5 minutes before the 30-minute scan. If we conservatively define normal arterial inflow as a peak Doppler velocity of 25 cm. per second or greater in the best artery, only 35% of our patients achieved this velocity at 5 minutes. Of the remainder 26% and 22% did not reach normal velocity values until 15 and 30 minutes, respectively, after the injection. By delaying initial measurements of velocity until 5 minutes, could the highest inflow velocity be missed and patients diagnosed incorrectly? The group at risk would be those who had good tumescence at 5 minutes and who had presumably already decreased the inflow velocities. Of the 280 patients 74 (26%) had greater than 10% tumescence at 5 minutes. Only 6 of these 74 patients did not reach velocities of 25 cm. per second or more in the best artery at some time during their study. In conclusion, our study clearly supports delaying the initial scan until 5 minutes, since only 6 of our 280 patients (2.1%) may have been incorrectly diagnosed. The study also strongly argues for additional scans until 30 minutes and self-stimulation when necessary.

Alprostadil↗
PubMed1993

Overtraining affects male reproductive status.

OBJECTIVE: To substantiate the hypothesis that strenuous exercise disrupts the hypothalamic-pituitary-gonadal axis in men. DESIGN: Longitudinal study. SETTING: Normal human volunteers in an academic research environment. PATIENTS: Five endurance-trained men (maximum oxygen consumption 65.4 +/- 3.6 mL/kg per minute [means +/- SEM]) with normal spermatogenic and hormonal profiles. INTERVENTIONS: Semen and blood samples were collected bimonthly before, immediately after, and 3 months after overtraining, which was defined as twice the previous average weekly training volume with unchanged intensity. MAIN OUTCOME MEASURE: Testosterone, cortisol, and sperm concentration. RESULTS: Basal T levels decreased to 5.37 +/- 67 ng/mL from 8.68 +/- 93 ng/mL (conversion factor to SI unit, 3.47) immediately after overtraining and basal cortisol levels increased to 215.3 +/- 31 ng/mL from 145.7 +/- 27 ng/mL (conversion factor to SI unit, 2.76). This inverse relationship was highly correlated (r = -0.92). Both cortisol and T levels returned to pretraining values 3 months after resumption of previous training volume. Sperm count (91 +/- 23.3 x 10(6)) decreased significantly by 43% immediately after overtraining (52 +/- 6.8 x 10(6)) and by 52% 3 months after overtraining (44.5 +/- 20 x 10(6)). However, all values remained within normal range and would not be expected to affect fertility. CONCLUSIONS: Our results indicate that overtraining reduces T levels, which is highly correlated with an increase in levels of cortisol and possibly a subsequent decrease in sperm concentration 74 days later.

Adult↗
PubMed1993

Experience with triple-drug therapy in a pharmacological erection program.

A group of 170 impotent men achieved usable erections during a 26-month period with a combination of papaverine, phentolamine and prostaglandin E1 (triple-drug therapy) injected intracorporeally. Of the patients 146 elected to enter a pharmacological erection program using this combination. Patient age ranged from 24 to 85 years and the average duration on the program was 11.2 months. Average injection volume was 0.36 cc per injection (range 0.1 to 1). Among those patients managed by our nurse clinician, only 3 episodes of priapism were encountered (1.7%). Scarring was documented in 7 of 170 patients (4.2%) 1 week to 21 months after starting the injections. Pain was encountered in 6 of 170 patients (3.5%). A superior dose response coupled with a low incidence of priapism, pain and scarring have led us to use triple-drug therapy as our agent of choice in the pharmacological management of erectile dysfunction.

Adult↗
PubMed1993

Effect of platelet-activating factor (PAF) on human spermatozoa-oocyte interactions.

The effect of exogenous platelet-activating factor (PAF) on human spermatozoa was examined by monitoring acrosomal status and hamster oocyte penetration. Induction of the acrosome response by PAF was dose, and time, dependent and required capacitated spermatozoa. Addition of 10(-14) mol PAF l-1 enhanced the acrosome reaction eightfold compared with controls treated with human serum albumin (HSA). Similar concentrations of lyso-PAF failed to induce acrosomal loss and preincubation of spermatozoa with CV3988, an inhibitor of PAF, prevented PAF induction of the acrosome reaction. PAF significantly increased the number of zona-free hamster oocytes penetrated compared with controls (9.8 +/- 0.5 of 25 oocytes were penetrated by control spermatozoa compared with 23.3 +/- 0.8 out of 25 oocytes penetrated after incubation of spermatozoa with 10(-14) mol PAF l-1; 93% of all oocytes were penetrated by at least one spermatozoon following incubation with PAF), and also increased the number of decondensed spermatozoa found per egg during the sperm penetration assay (from 1.7 +/- 0.3 spermatozoa/egg with control spermatozoa to 3.3 +/- 0.5 spermatozoa/egg with PAF-treated spermatozoa). PAF-induced increases in acrosome reaction and sperm penetration assay values were similar to effects obtained with human follicular fluid and were calcium dependent. Induction of the acrosome reaction by physiological concentrations of PAF appeared to be morphologically similar to the response induced by follicular fluid as assessed by electron microscopy.

Acrosome↗
PubMed1991

Simultaneous resection of renal carcinoma and abdominal aortic aneurysm.

A 62-year-old man with a 6.5 cm abdominal aortic aneurysm and coexistent left renal cell carcinoma was treated by simultaneous radical left nephrectomy and abdominal aortic aneurysm repair. Care was taken to avoid potential infection of the bypass graft by inadvertent contamination with urine. Pathologic examination of the left kidney revealed a renal cell carcinoma, clear cell type, with no evidence of invasion into the renal vein or lymph node metastases. The patient had an uncomplicated recovery and is well and free of disease four years after operation. In cases of equivalently life threatening surgical diseases, simultaneous resection is warranted.

Aorta, Abdominal↗
PubMed1991

Hypogonadal impotence treated by transdermal testosterone.

The transdermal therapeutic system for testosterone (TTS-T) (ALZA Corp.), applied to the scrotal skin for twenty-two hours daily, was tested for twelve weeks on 4 men with hypogonadal impotence; 2 of these men wore TTS-T for as long as twenty-six months. The 40 cm2 system delivered a daily dose of 2.8 +/- 0.16 (S.E.) mg (nominal dose 2.4 mg) and the 60 cm2 system delivered a dose of 3.99 +/- 0.24 mg (nominal dose 3.6 mg). Both systems promptly increased serum testosterone and dihydrotestosterone (DHT) to physiologic levels, restoring normal erectile activity with an increased frequency of ejaculation and a positive effect on both mood and energy. There were no changes in serum sex binding globulin and estradiol, prostate or breast size, hematologic or liver function measures, or urinary flow and frequency. There were no significant changes in serum cholesterol or low-density lipoproteins, but high-density lipoproteins tended to decline slightly. There were no dermatologic problems associated with the system. The tenfold increase in DHT over baseline levels was attributed to 5-alpha reduction of testosterone in the scrotal skin. The TTS-T is convenient, reliable, and mimics normal physiologic testosterone secretion and levels more closely than conventional methods of testosterone replacement.

Administration, Cutaneous↗
PubMed1991

Vacuum tumescence devices: the role of papaverine in the selection of patients.

We conducted a prospective study to determine the positive predictive value of papaverine testing to select patients in whom a vacuum constriction device would be a successful alternative to operative management of impotence. A total of 30 men presenting to an impotence clinic was evaluated with a series of papaverine dosages up to 60 mg. These patients then received a physician-administered trial of a vacuum constriction device, followed by 3 months of home use and a repeat objective evaluation. Initial responses to the device were poor, with 46% of the patients (14) achieving a rigid erection. However, after 3 months of home use 83% of the patients (25) achieved a rigid erection. The positive predictive value of a good response to the papaverine trial was 94%.

Equipment Design↗
PubMed1991

Subclinical varicocele: the effectiveness of varicocelectomy.

To investigate the controversial concept that subclinical varicoceles are detrimental to spermatogenesis, we undertook a prospective study of the effectiveness of surgery in 56 infertile men with clinical and subclinical varicoceles. Our statistical approach specifies improvement as a change from individual baseline level. The over-all variability in sperm counts precluded the demonstration of significant changes in sperm density consequent to surgery. Improvement in sperm motility was seen in both groups, being slightly greater in the subclinical group. The changes were inversely related to baseline levels and increased with time from surgery. Therefore, it appears that the detection of subclinical varicoceles may be warranted in infertile men with abnormal semen parameters.

Humans↗
PubMed1991

Screening assays for immunologic infertility: a comparison study.

Because the immunobead antisperm antibody test (IBT) is difficult to learn and results are heavily operator-dependent, we compared findings on IBT with those of SpermMAR and SpermCheck in 58 patients to determine whether the latter two tests could demonstrate improved screening ability. Assays performed on both sperm and serum (i.e., direct and indirect) yielded 100% positive predictive values when IBT was used as the standard. Both SpermCheck and SpermMAR are easier to perform, and, as the former has a slightly greater sensitivity, we recommend SpermCheck for the detection of immunologic infertility.

Autoantibodies↗
PubMed1991

MR imaging of the seminal vesicles.

MR imaging (0.35 and 1.50 T) was used to assess the appearance of the seminal vesicles. The size and signal intensity of normal seminal vesicles vary with the age of the subject. In general, on T2-weighted images, the signal intensity of normal seminal vesicles is lower than that of fat in prepubertal children, similar to or higher than that of fat in adults, and similar to or lower than that of fat in patients older than 70 years of age. Endocrine and radiation therapy will influence the size and signal intensity of the seminal vesicles. The purpose of the essay is to illustrate the spectrum of seminal vesicle disease, including congenital anomalies, inflammation, and neoplastic disease. Although MR imaging is helpful in depicting seminal vesicle abnormalities, it does not allow differentiation of benign from malignant disease, distinction of hemorrhage due to tumor invasion from postbiopsy changes, or distinguishing between glandular obstruction due to tumor infiltration and mechanical compression.

Genital Diseases, Male↗
PubMed1991

Varicoceles. Radiologic diagnosis and treatment.

The association of clinically apparent varicoceles with male subfertility and infertility has been noted in the urology literature since the late nineteenth century, and surgical ligation of varicoceles has been considered appropriate therapy in an attempt to improve semen quality and increase fertility for the past 40 years. It has been established by several authors cited herein that varicocele size does not predict prognosis after ligation reliably. Because subclinical varicoceles may affect testicular function and histologic characteristics adversely and because age at time of therapy may affect probability of successful enhancement of fertility, the interest of radiologists and urologists has been directed toward diagnosis and treatment of both clinically obvious and clinically occult varicoceles, particularly in young adult men or adolescent boys. Testicular growth after varicocele ligation in adolescent boys also suggests a benefit from early intervention. Sonographic evidence of a varicocele must be correlated with analysis of semen for sperm density, motility, and morphology, as not all patients with varicoceles are infertile. Although surgical therapy is standard for varicocele occlusion, fairly extensive evidence exists to show that percutaneous transvenous occlusion of varicoceles is feasible, safe, and effective, particularly in the setting of varicocele recurrence after conventional surgical treatment.

Embolization, Therapeutic↗
PubMed1991

Platelet-activating factor in sperm from fertile and subfertile men.

STUDY OBJECTIVE: To examine the proposed role of platelet-activating factor (PAF) as a mediator of sperm function first by quantitating the concentration of PAF in sperm and second by incubating sperm with PAF and assessing the change in sperm motion parameters with a computerized motion analysis system. DESIGN: Retrospective, case-control study. SETTING: University hospital urology clinic. PATIENTS: Concentrations of PAF were measured in sperm from 6 randomly chosen normal donors and 8 asthenozoospermic patients. The change in sperm motion parameters was assessed in sperm from 10 randomly chosen normal donors and 7 asthenozoospermic patients. RESULTS: Platelet-activating factor concentrations were significantly higher (P less than 0.05) in spermatozoa from asthenozoospermic patients (149 +/- 18.0 fmol/10(6) sperm) than in sperm from normal donors (91.9 +/- 13.0 fmol/10(6) sperm). Exogenous PAF did not enhance the percent motility of precapacitated or capacitated sperm from either patients or donors, and computerized semen analysis revealed no enhancement of sperm motion parameters in asthenozoospermic patients after addition of PAF to either precapacitated or capacitated sperm. CONCLUSION: Platelet-activating factor does not appear to have therapeutic value as a means of enhancing sperm motility.

Case-Control Studies↗
PubMed1990

Optimizing the sperm penetration assay with human follicular fluid.

Major limitations of the conventional sperm penetration assay are the inability to assess several aspects of sperm function (zona binding and penetration) and the absence of human ovulatory products known to influence fertilization. We therefore modified the sperm penetration assay by the addition of human follicular fluid (FF) to induce the acrosome reaction in an attempt to improve the false-negative rate of the conventional technique. In 26 patients with negative results, results became positive in 20 with human FF and the acrosome reaction increased fourfold. In 19 different men, we compared the results of the conventional and modified assays with outcome of in vitro fertilization. The false-positive rate was the same, but the false-negative rate was reduced from 40% to 7% with the addition of human FF.

Acrosome↗