Biomedical subjects
Publications and source records attributed to D C Merrill.
Giant prostatic hyperplasia (GPH) is an uncommon pathologic entity with only 10 reported cases of prostate glands exceeding 500 g. We report the uncomplicated removal of a 526-g prostatic adenoma by simple retropubic prostatectomy.
This multicenter, cooperative study represents the initial United States experience using an expandable, titanium intraprostatic stent in 68 patients (60 to 93 years old). The stents were inserted under direct vision and expanded to 33F using a balloon catheter. All patients had a symptom score analysis, and underwent measurement of peak urine flow and rate and post-void residual urine volume as part of the initial evaluation. Patients were seen at approximately 1, 3, 6 and 18 months after stent insertion (mean followup 16 months). Of the 68 patients 38 presented in urinary retention. The type of anesthesia used included general anesthesia in 6 patients, spinal or epidural anesthesia in 24, intravenous sedation in 20 and intraurethral lidocaine only in 18. All patients were able to void spontaneously within 36 hours after stent insertion. Symptom scores decreased from 16.8 to 3.9, 6.3, 5.0, 5.7 and 3.2 at approximately 1, 3, 6, 12 and 18 months, respectively. Peak urine flow rate increased from 3.9 to 13.8, 11.5, 11.2, 12.4 and 14.4 ml. per second at approximately 1, 3, 6, 12 and 18 months, respectively. Post-void residual urine volume decreased from 74.4 to 30.1, 29.2, 19.8 and 40.2 ml. at approximately 1, 3, 6 and 12 months, respectively. Of the initial 68 patients 5 died of the underlying disorder (all voiding satisfactorily with the stent in place) and 17 underwent uneventful stent removal (10 for technical failure and 7 for treatment failure). Technical failures were secondary to either inaccurate positioning or improper stent sizing. Of the 58 patients with proper placement of the stent and no technical failures 46 (79%) had improvement in symptom scores and urine flow rate. Transient hematuria was noted in 43 patients (63%) and usually resolved within 48 hours. None of the 6 urinary tract infections (9%) was recurrent. In conclusion, the titanium intraprostatic stent, when properly placed, is a promising therapeutic alternative to prostatectomy or long-term catheterization in high risk obstructed patients or those in urinary retention. Studies are currently in progress to determine the long-term efficacy of this therapeutic modality.
Endotracheal suctioning of intubated infants produces profound changes in cardiovascular and cerebral hemodynamics, but the mechanisms regulating these changes are not fully understood. To determine the role of the autonomic nervous system in regulating these physiologic changes, we investigated the effects of endotracheal suctioning on heart rate (HR), mean arterial blood pressure (MABP), and renal sympathetic nerve activity (RSNA) in nine ventilated newborn lambs. In the first part of the study (n = 6), ventilation was interrupted for suctioning. With suctioning (15 s), HR decreased by 39 +/- 6% (p < 0.05), whereas MABP and RSNA increased significantly (p < 0.05) by 36 +/- 5% and 68 +/- 8%, respectively. These changes were significantly (p < 0.05) larger than changes observed during disconnection from the ventilator (15 s) without suctioning. Administration of atropine (0.02 mg/kg) blocked the HR response to suctioning without altering MABP or RSNA changes. After bilateral vagotomy, suctioning produced no changes in any parameter. When a closed tracheal suction system was used and ventilation was maintained, suctioning again resulted in significant (p < 0.05) increases in MABP (+10 +/- 3%) and RSNA (+34 +/- 5%) and a decrease in HR (-15 +/- 4%). These data suggest that suctioning stimulates sympathoexcitatory receptors localized in large airways whose afferent fibers course within the vagus, resulting in increased sympathetic activity, which induces peripheral vasoconstriction and elevates MABP. In contrast, the HR response appears to be mediated by increased parasympathetic activity as this is abolished by atropine.
We conducted this pilot clinical study to investigate the safety, primarily acute toxicity, of green light (514.5 nm) whole bladder photodynamic therapy (PDT) in human bladders with transitional cell carcinoma. We enrolled five patients who were scheduled to undergo radical cystectomy and urinary diversion for locally muscle invasive bladder cancer. Four patients received intravenous injection of Photofrin at 1 mg/kg, while one patient received no drug, 48 hr before undergoing green light whole bladder photoactivation with light doses of 20-60 J/cm 2. Each patient underwent radical cystectomy on day 7 following light treatment. Post-PDT evaluation included daily monitoring of voiding symptoms, cystometric measurements of bladder capacity, and gross and histopathologic examination of the excised bladders. Our results show that the intensity of acute bladder irritation and acute post-PDT loss in bladder volume depended on the light dose and extent of bladder tumor with the associated inflammation. There was no transmural bladder injury and no treatment related morbidity. These data on acute toxicity suggest that green light whole bladder PDT treatment with 1 mg/kg of Photofrin and 20-40 J/cm 2 of laser power is safe.
The purpose of this study was to characterize the developmental changes in baroreflex function during fetal and postnatal life in sheep. Resting mean arterial blood pressure increased significantly from 55 +/- 2 mmHg in fetuses to 86 +/- 3 mmHg in newborn lambs and to 105 +/- 4 mmHg in 4- to 6-wk-old lambs. The sensitivity (gain) of the renal sympathetic nerve activity (RSNA) response to baroreceptor stimulation was greater (P < 0.05) in fetuses (-7.7 +/- 1.9%/mmHg) than in newborn (-2.9 +/- 0.1%/mmHg) and 4- to 6-wk-old lambs (-2.2 +/- 0.2%/mmHg). The threshold and saturation pressures for the baroreflex function curve were lower (P < 0.05) in fetuses (44 +/- 2 and 61 +/- 2 mmHg) than in newborn (59 +/- 4 and 106 +/- 5 mmHg) or 4- to 6-wk-old lambs (78 +/- 5 and 132 +/- 6 mmHg). Similar findings were observed when the heart rate response to baroreceptor stimulation was examined. Additional experiments were performed in newborn and 4- to 6-wk-old lambs to determine whether the rise in arterial blood pressure associated with postnatal maturation contributed to baroreflex resetting. Sustained elevation of arterial blood pressure by 15-20 mmHg for over 90 min did not reset the baroreflex function curve in either newborn or 4- to 6-wk-old lambs.(ABSTRACT TRUNCATED AT 250 WORDS)
Fetal therapy continues to be an exciting yet controversial field. In utero treatment of a variety of fetal conditions is discussed: parvovirus B19 infection, fetal thyroid dysfunction, fetal ovarian cysts, twin-twin transfusion syndrome, and fetal hemolytic disease. Fetal surgery continues to be controversial. Despite considerable publicity, fetal surgery appears to be rarely, if ever, truly indicated. A new area of fetal therapy, ie, antenatal transplantation of fetal liver stem cells, is discussed.
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Patient satisfaction with the Mentor inflatable penile prosthesis was assessed by sending a thirty-six-item questionnaire to 251 patients who had undergone implantation of the device by the senior author (D.C.M.). A total of 152 (61%) of the patients responded. Recovery time, satisfaction, reasons for dissatisfaction, perceptions of erection quality, and psychosexual parameters were evaluated. Eight-eight percent of the patients were engaging in regular sexual activity. Depending on the definition of satisfaction, 81-89 percent of the respondents reported that they were satisfied with the prosthesis. Sixty-eight percent of the survey group were satisfied with the length, width, and firmness of their prosthetic-induced erection. The majority of patients reported improvement in psychosexual functioning after implantation. Reasons for dissatisfaction included inadequate penile length, insufficient firmness, and difficulty with inflation and deflation of the penile cylinders.
Present-day whole bladder photodynamic therapy (WBPDT) is cumbersome and time consuming because cystoscopic and ultrasonic manipulations are necessary to position the light emitter within the bladder. More important, WBPDT is inherently unsafe and often ineffective since neither uniform photoirradiation nor accurate light dosimetry can be achieved with the techniques employed to photoirradiate the bladder wall. The intravesical laser catheter (IVLC) eliminates the need for cystoscopy and ultrasonography because passage of the treatment fiber into the catheter's central lumen automatically positions its light-diffusing tip within the center of the bladder. Use of the IVLC delivery system also assures accurate photoirradiation of the bladder wall since inflation of the catheter's balloon transforms the asymmetric bladder into a sphere of known diameter. The light sensor incorporated in the balloon wall provides a method to monitor light fluence and measure total light dose. When provided the parameters of bladder volume, laser energy output, and desired light dose, the computerized control system calculates treatment time and automatically adjusts the period of photoirradiation to compensate for variations in laser light production, energy losses during transmission, and for variations in light intensity resulting from the integrating sphere effect of the bladder wall. This delivery system also increases the safety of WBPDT since the monitor automatically discontinues treatment if any unsafe situation, with respect to light fluence, develops during photoirradiation.
Previous studies have shown that electroanalgesia is an effective method of reducing postoperative pain in patients who have urologic surgery. All prior studies of postperative transcutaneous electrical nerve stimulation (TENS) have employed TENS stimulators which were designed for the control of chronic pain. Disadvantages to the use of standard TENS stimulators in postoperative patients include the high cost of the devices and their operative complexity which make it difficult for staff and patients to use them. FasTENS is a lightweight, relatively inexpensive disposable TENS stimulator which has been designed specifically for use in postoperative patients. We evaluated the effectiveness of FasTENS in patients who had implantation of an inflatable penile prosthesis, radical retropubic prostatectomy, or radical nephrectomy. Patients treated with FasTENS used 60 percent less pain medication (P less than 0.001) and made 61 percent fewer requests for Demerol injections (P less than 0.001) than did control patients who were not treated with postoperative electroanalgesia. FasTENS was most effective in patients who had radical prostatectomy or penile prosthetic surgery. FasTENS was not cost-effective or practical in patients who had radical nephrectomy.
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Studies were carried out in normal male subjects (n = 6, age 20-35 years) to determine the interaction of angiotensin II and plasma sodium on aldosterone secretion. These relations were quantified by elevation of plasma sodium with an infusion of 5% sodium chloride (4 ml/kg/30 min i.v.) with measurements of plasma aldosterone, atrial natriuretic factor (ANF), and arginine vasopressin (AVP) over 3 hours. Two hours before sodium chloride infusion, an intravenous infusion of angiotensin II was begun at 0.5 or 5.0 ng/kg/min and continued throughout the study. Plasma potassium was maintained constant by the addition of potassium to the infusate. NaCl/KCl infusion raised plasma sodium 4 meq/l with no decreases of plasma potassium. Plasma aldosterone averaged 7 +/- 1.8 ng/dl before NaCl infusion in subjects infused with 0.5 ng angiotensin II and was not significantly reduced with sodium chloride infusion. Angiotensin II infused at 5 ng/kg/min resulted in average plasma aldosterone levels of 31 +/- 3.6 ng/dl, which sodium chloride infusion decreased to 16.6 +/- 1.3 ng/dl (p less than 0.05) in 60 minutes. Plasma aldosterone remained depressed for the remaining period of study. Plasma ANF increased from 40 to 60 pg/ml with sodium chloride infusion. We conclude that small physiological elevations of plasma sodium concentrations can signal substantial decreases of plasma aldosterone in normal human subjects in situations where plasma angiotensin II is moderately elevated. The precise mechanisms of these responses remain to be determined.
The standard Mentor inflatable is an extremely reliable prosthesis that will provide complete satisfaction in 87 to 99 per cent of the patients in whom it is implanted. The proved long-term reliability and superior functional characteristics of the three-component Mentor prosthesis make it a standard investigators may use to compare the recently introduced mechanical and modified inflatable prostheses. The short-term results of the new Mentor GFS prosthesis also are encouraging. The new prosthesis provides an attractive alternative to the standard inflatable prosthesis in patients with normal-sized genitalia, especially for surgeons who prefer to implant the device through a penoscrotal incision.
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Orchiectomy is the preferred method for treating patients with metastatic adenocarcinoma of the prostate (MAP) because it is safer and more reliable than estrogen therapy. Nonetheless, a survey of Northern California urologists showed that 57 percent of their patients with MAP were treated with diethylstilbestrol (DES) rather than orchiectomy. Factors which determined treatment selection include the physician's belief that estrogen therapy was either equally (35%) or more (22%) effective than orchiectomy and the patients' rejection of orchiectomy even if it were recommended to them (20-30%). The survey also showed that previous attempts to increase the acceptability of orchiectomy by performing a subcapsular procedure have failed because urologists do not believe the procedure is effective (45%), or that subcapsular orchiectomy provides a satisfactory cosmetic result (20%). Recent laboratory and clinical investigations have shown that complete and subcapsular orchiectomy were equally effective in reducing serum testosterone. Patient acceptance of subcapsular orchiectomy may be increased by utilizing the term testicular curettage, which does not imply castration, to describe the procedure and by implantation of intracapsular testicular prostheses to restore normal testicular anatomy after the testicles' hormone-producing tissue has been removed.
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The Mentor inflatable penile prosthesis has been implanted in 301 patients during the last 60 months, of whom 3 died of unrelated causes and 13 have been lost to followup. Of the remaining 285 patients 96.8 per cent are presently using the device. A life table analysis of 253 implantations performed since 1983 shows that 97 per cent of the prostheses presently being implanted will survive 48 months without mechanical failure. There have been no wear-induced leaks or aneurysms in the 602 cylinders implanted. Complications that resulted in permanent device loss or necessitated a second operation were owing to mechanical problems in 3 per cent, infection in 2.3 per cent and surgeon error in 1.7 per cent of the cases. This clinical study demonstrates the 5-year reliability of cylinders constructed from polyurethane, the reliability of the Mentor snap-on connector system and the increased durability of nylon-reinforced silicone tubing.