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Biomedical subjects

A Nehra

Publications and source records attributed to A Nehra.

At least 37 records · Page 2Linked to original sources
PubMed2000

Medical and surgical advances in the radical prostatectomy patient.

Maintaining the quality of life after surgery in the radical prostatectomy patient is of paramount importance. One of the major dilemmas in surgical management of radical retropubic prostatectomy (RRP) is preservation of the neurovascular bundle and, hence, erectile function and the continence mechanism. This manuscript addresses anatomical considerations for the surgeon and discusses the following issues with regard to medical and surgical therapies: (1) incidence of erectile dysfunction solely due to complications during RRP; (2) nerve damage during RRP; (3) vascular damage during RRP; (4) current medical and surgical therapies for restoring or maintaining potency; and (5) new advances on the horizon for management of the prostatectomy patient. International Journal of Impotence Research (2000) 12, Suppl 4, S47-S52.

Blood Vessels↗
PubMed2000

Grading and staging of bladder carcinoma in transurethral resection specimens. Correlation with 105 matched cystectomy specimens.

We compared the grading and staging of transurethral resection of the bladder (TURB) and cystectomy specimens for 105 patients who underwent radical cystectomy for urothelial carcinoma between 1980 and 1984. Of 105 patients, 96% underwent cystectomy within 100 days of TURB (median interval, 10 days). Grading was performed according to the 1998 World Health Organization/International Society of Urologic Pathology grading system and staging according to the 1997 TNM classification. Histologic grade was low-grade, 13; high-grade, 92 in TURB specimens; low-grade, 17; high-grade, 88 in cystectomy specimens. Pathologic stage was Ta, 15; T1, 55; and T2, 35 in TURB specimens; Ta, 5; T1, 19; T2, 19; T3, 46; and T4, 16 in cystectomy specimens. Histologic grade at TURB was associated with pathologic stage at cystectomy (P < .001). When all advanced-stage (muscle-invasive) carcinomas (pT2 or more) were considered together, 55 patients were understaged by TURB, 4 had higher stage in TURB than in cystectomy, and 46 were the same stage as by cystectomy. Forty-three of 55 patients with stage T1 carcinoma at TURB had advanced-stage carcinoma at cystectomy, including 34 who had extravesicular extension (pT3 or more). We found pathologic understanding by TURB occurs in a significant number of patients with bladder cancer; the newly proposed grading system predicted final pathologic stage.

Adult↗
PubMed2000

Treatment of endocrinologic male sexual dysfunction.

Erectile dysfunction affects 20 million to 30 million men in the United States, and it has been reported that a significant number of impotent men (2.1% to 23%) have subnormal serum testosterone levels. A decline in serum levels of testosterone accompanies normal aging in men; however, the pathophysiological and clinical consequences of this decline are unknown. Appropriate hormonal therapy for men with hypogonadism requires an understanding of the normal physiologic regulation of the testes and the pathophysiology of underlying testicular dysfunction. This article reviews those mechanisms.

Administration, Cutaneous↗
PubMed1999

Urothelial papilloma of the bladder. Clinical and biologic implications.

BACKGROUND: An international consensus has been reached regarding diagnostic criteria for papilloma of the urinary bladder. However, the incidences of recurrence and progression in patients with urothelial papilloma are uncertain. METHODS: The population for this study consisted of 52 patients who were diagnosed with urothelial papilloma of the bladder at the Mayo Clinic between 1914 and 1998. All histologic slides were reviewed and fulfilled the diagnostic criteria of urothelial papilloma from the 1998 World Health Organization/International Society of Urological Pathology classification system. No patients had previous or coexistent urothelial carcinoma, and none were treated after biopsy. RESULTS: The mean patient age at diagnosis was 57 years (range, 22-89 years). The male-to-female ratio was 1.9:1. The mean follow-up was 9.8 years (range, 0.1-58 years). Four patients developed recurrent papilloma (mean interval from diagnosis to recurrence, 3.3 years); 1 other patient developed papillary neoplasm of low malignant potential (Ta WHO Grade 1 papillary urothelial carcinoma) 6 years after the initial diagnosis of papilloma. None of these patients developed dysplasia, carcinoma in situ, or invasive urothelial carcinoma or died of bladder cancer. CONCLUSIONS: Patients with urothelial papilloma have a low incidence of recurrence and rarely, if ever, develop urothelial carcinoma.

Adult↗
PubMed1999

Hemangioma of the urinary bladder.

BACKGROUND: Hemangioma of the urinary bladder is rare and the long term outcome of patients is unknown. METHODS: The authors evaluated the clinical and pathologic findings in 19 patients with a vesical hemangioma. All patients were treated at the Mayo Clinic between 1932-1998 and had histologic confirmation of the diagnosis. Hemangioma was classified into cavernous, capillary, or arteriovenous types based on conventional criteria from other sites. Clinical information was obtained from chart review. The mean follow-up of the patients was 6.9 years (range, 0.3-25 years). RESULTS: The mean patient age at the time of diagnosis was 58 years (range, 19-76 years) and the male-to-female ratio was 3.7:1. Patients typically presented with macroscopic hematuria and endoscopic findings usually were nonspecific. The diagnosis of hemangioma was suspected in 3 patients (16%) prior to biopsy. There was a predilection for the posterior and lateral walls and the tumor usually was small (range, 0.2-3 cm; median, 0.7 cm) and solitary. The histologic types of hemangioma were cavernous (15 cases), capillary (2 cases), and arteriovenous (2 cases). All patients were treated with biopsy with or without fulguration, except for one patient who was treated with a partial cystectomy. No patients developed a recurrence during a mean follow-up of 6.9 years. CONCLUSIONS: Patients with hemangioma of the urinary bladder have a favorable outcome. Biopsy and fulguration are effective for hemangioma of the bladder when the lesion is small.

Adult↗
PubMed1999

Tumor size predicts the survival of patients with pathologic stage T2 bladder carcinoma: a critical evaluation of the depth of muscle invasion.

BACKGROUND: Accurate examination of radical cystectomy specimens is critical for stratifying patients into prognostically important groups and determining the need for adjuvant treatment. Evidence has accumulated that cancers invading the superficial muscle wall (T2a) behave similarly to those invading the deep muscle wall (T2b). Quantitative analysis of the depth of invasion in relation to patient outcome is needed. METHODS: The authors systematically evaluated the depth of invasion by micrometer measurement and its relation to the survival of 64 patients with bladder carcinoma pathologic classification as pT2 who had long term follow-up after radical cystectomy. Numerous clinical and pathologic variables were analyzed with univariate and multivariate Cox proportional hazards models. The mean age of patients was 64 years, and their mean follow-up was 8.3 years. RESULTS: There was no significant difference in clinical outcome between patients with T2a carcinoma and those with T2b. Lymph node metastasis and tumor size were each significantly associated with distant metastasis free and cancer specific survival. Ten-year distant metastasis free and cancer specific survival were 100% and 94%, respectively, for patients with tumors <3 cm (P = 0.006) and 68% and 73%, respectively, for patients with tumors > or = 3 cm (P = 0.005). After adjustment for lymph node status, tumor size maintained significance in predicting distant metastasis free survival (risk ratio, 1.5; 95% confidence interval, 1.1-2.0; P = 0.009) and cancer specific survival (risk ratio, 1.5; 95% confidence interval, 1.1-1.9; P = 0.01). Age was associated with recurrence free survival and all-cause survival. None of the other variables, including gender, vascular invasion, presence of carcinoma in situ, pathologic classification (T2a vs. T2b), depth of invasion, depth of muscle invasion, ratio of depth of invasion to bladder wall thickness, and percentage of muscle wall invasion, were significantly associated with patient outcome. CONCLUSIONS: The findings of this study indicate that the subclassification of T2 bladder carcinoma by depth of muscle invasion is of no prognostic value; conversely, tumor size, an easily measured factor, is predictive of distant metastasis free and cancer specific survival.

Adult↗
PubMed1999

Transforming growth factor-beta1 (TGF-beta1) is sufficient to induce fibrosis of rabbit corpus cavernosum in vivo.

PURPOSE: The pleotropic cytokine TGF-beta1 which induces connective tissue synthesis, and inhibits the growth of smooth muscle cells, has been implicated in corpus cavernosum fibrosis. The objective of this study was to determine the dose and time dependence of TGF-beta1 as an active agent in penile corporal fibrosis in an animal model. MATERIALS AND METHODS: A time release method of delivery was developed using sodium alginate microspheres containing recombinant human (rh) TGF-beta1. New Zealand White rabbits were injected intracorporally with a single alginate microsphere either with or without rh-TGF-beta1. Dosage was varied from 325 to 1500 ng./bead. Animals were sacrificed at either three or five days post injection and the penises removed en bloc, examined, and processed for quantitative histomorphometric analysis, staining the sections with Masson's trichrome. RESULTS: Alginate microspheres containing [125I]-rh-TGF-beta1 showed slow-release kinetics (t1/2 = 10.5 hours). Histomorphometric analysis of 60 sets of high powered fields/treatment/ animal showed dose dependent decreases in percentage of corporal smooth muscle with TGF-beta1 treatment (750 to 1500 ng./bead). Placebo (alginate microspheres alone) had trabecular smooth muscle content comparable to values previously reported for untreated rabbit corpus cavernosum. CONCLUSIONS: This study confirms that TGF-beta1 induces fibrosis in situ by altering connective tissue synthesis and hence the structure of the corpus cavernosum. Injection of rh-TGF-beta1 impregnated alginate microspheres into the corpus cavernosum resulted in dose-dependent decreases in percentage of corporal smooth muscle.

Animals↗
PubMed1999

Pharmacotherapeutic advances in the treatment of erectile dysfunction.

An estimated 20 million to 30 million American men have erectile dysfunction (ED). The past 2 decades of research defining erectile physiology and investigating the pathogenesis of ED have led to the recognition of a predominantly vascular basis for organic male sexual dysfunction. These scientific advances have laid the foundation for the advent of pharmacotherapies. The Food and Drug Administration approval of intracavernosal, intraurethral, and oral pharmacotherapeutics for ED has revolutionized non-surgical management of this condition. The primary care physician is faced with the challenges of diagnosis and treatment of ED, as well as referral of patients to urologists. In this article, erectile physiology and pathophysiology are reviewed, and pharmacotherapeutics are classified and discussed by their mechanisms of action and the means of administration. A thorough understanding of these new therapeutic options is key to the accurate diagnosis and successful treatment of ED and maximal patient satisfaction and care.

Adrenergic alpha-Antagonists↗
PubMed1998

Cavernosal expandability is an erectile tissue mechanical property which predicts trabecular histology in an animal model of vasculogenic erectile dysfunction.

PURPOSE: Reliable, clinically available, non-invasive measurements able to predict trabecular histology without the need for erectile tissue biopsy would improve impotence management, since the percentage of trabecular smooth muscle content has been shown to be associated with corporal veno-occlusive dysfunction. The purpose was to identify whether the erectile tissue mechanical property, cavernosal expandability, correlated with the percentage of trabecular smooth muscle content in an animal model of hypercholesterolemia and ischemic-induced corporal fibrosis. MATERIALS AND METHODS: New Zealand White rabbits (6 to 7 months old, 3 to 3.5 kg.), were divided into control (n = 7), hypercholesterolemic (n = 5, 0.5% cholesterol diet) and atherosclerotic groups (n = 8, 0.5% cholesterol diet with balloon de-endothelialization). At 16 weeks, the corpora cavernosa were removed en bloc and submerged in physiologic salt solution, and volume-pressure data were plotted at 20 mm. Hg pressure intervals under trabecular smooth muscle relaxation. Cavernosal expandability, X, (the measure of the ability to achieve high corporal expansion at relatively low intracavernosal pressure) and tunical distensibility, V(E)/V(F), (relative volume of fully erect to flaccid penis) were calculated. Erectile tissue was assessed by computer-assisted color histomorphometry with Masson's trichrome stained sections (30 to 45 high power fields/animal) to assess percentage of trabecular smooth muscle content. RESULTS: The overall mean percentage of trabecular smooth muscle content and mean cavernosal expandability values were 45.4 +/- 1.6, 39.2 +/- 0.9, 33.9 +/- 0.6 and 0.0165 +/- 3.04 x 10(-3), 0.0116 +/- 1.63 x 10(-3), 0.0118 +/- 1.26 x 10(-3) mm. Hg(-1) for the control, hypercholesterolemic and atherosclerotic groups, respectively (r = 0.87). Significant differences in trabecular smooth muscle content were observed among all 3 groups, and in cavernosal expandability, between control and atherosclerotic groups, as well as between control and hypercholesterolemic groups but not between atherosclerotic and hypercholesterolemic groups. CONCLUSIONS: The erectile tissue mechanical property, cavernosal expandability, correlated with erectile tissue structural quality. Since cavernosal histology has been shown to predict corporal veno-occlusive function, it is hypothesized that the measurement of cavernosal expandability may become a valuable functional clinical parameter in the diagnosis and treatment of men with erectile dysfunction.

Animals↗
PubMed1998

Urological complications after kidney-pancreas transplantation.

PURPOSE: Urological complications are common after kidney-pancreas transplantation. Predictors of urological complication after transplantation have not been established. We studied the impact of urological complications on allograft function. In addition we evaluated age at transplantation, diabetic years before transplantation and preoperative bladder function as predictors of allograft pancreatitis, postoperative retention and urine leaks. MATERIALS AND METHODS: Urological complications in 65 cases (38 men, 27 women, mean diabetic years 21 +/- 6, mean age 33 +/- 7 years) who had transplants between December 1987 and January 1995 were reviewed. Preoperative urodynamics in 50 patients (77%) and voiding cystourethrogram in 40 (62%) were analyzed. Kidney-pancreas transplantation was completed using bladder drainage techniques. RESULTS: Mean followup was 44 +/- 27 months (median 40, range 1 to 93). Urological complications in 51 patients (79%) included urinary tract infection in 59%, hematuria in 26%, allograft pancreatitis in 19%, duodenal leaks in 17%, ureteral lesions in 9% and urethral lesions in 6%. Eleven duodenal leaks (8 leaks in less than 1 month) required surgical treatment. Nine leaks recurred in 7 patients. Allograft pancreatitis occurred 32 times (range 1 to 9) in 12 patients. Three patients had ureteral obstruction and 3 had ureteral leaks. Preoperative urodynamics included detrusor hyperreflexia in 8 patients, detrusor areflexia in 19, indeterminate in 5 and normal in 18. The 1-year patient, kidney and pancreatic allograft survival rates were 92, 91 and 86%; 2-year survival rates were 89, 88 and 80%, and 5-year survival rates were 61, 59 and 55%, respectively. CONCLUSIONS: Urological complications were common after transplantation but did not adversely affect allograft survival in our series. Age at transplantation, diabetic years preceding transplantation and preoperative bladder function were not significantly correlated with allograft pancreatitis, postoperative urinary retention or urine leaks. A prospective analysis of postoperative bladder function should be completed to improve understanding and possibly reduce morbidity of urological complications after transplantation.

Adult↗
PubMed1998

Erythropoietin-induced recurrent veno-occlusive priapism associated with end-stage renal disease.

This is the first report of a male hemodialysis patient experiencing recurrent dialysis-associated priapism that resolved when his concurrent erythropoietin dose was reduced from 2000 to 1500 U one time per week and held if his hemoglobin was greater than 10 g/dL. We discuss dialysis-associated priapism and the effects of erythropoietin on the coagulation cascade and male hormone levels in an effort to elucidate the etiology of priapism in this patient.

Adult↗
PubMed1998

Percutaneous core biopsy of the penis.

To describe the efficacy of percutaneous core biopsy of penile corporal tissue, on ten impotent men, the biopsy was performed with a 19 and a 20 gauge core biopsy co-axial system using an automatic biopsy device. All biopsies were performed on an outpatient basis under local anesthesia. Adequate biopsy specimens were obtained in all. Percutaneous core biopsy of the penis is a safe procedure that is technically easy to perform.

Anesthesia, Local↗
PubMed1998

Engineering analysis of penile hemodynamic and structural-dynamic relationships: Part I--Clinical implications of penile tissue mechanical properties.

PURPOSE: The least investigated physical determinant of penile rigidity has been penile tissue material properties. The goals in this study (Part I) were to define two penile mechanical parameters, cavernosal expandability X and tunical distensibility VE/VF, determine their magnitudes in humans and develop an analytical expression for penile volume as a function of these two tissue characteristics and intracavernosal pressure. METHODS: Dynamic infusion pharmacocavernosometry was performed in 21 impotent patients (age 43 +/- 19 y) to provide human geometric, hemodynamic and structural data. A mathematically derived model of hemodynamic and structural-dynamic characteristics of penile erection was developed (Parts I, II, III) incorporating penile tissue mechanical qualities. RESULTS: Cavernosal expandability X provided a measure of the ability to approach maximum volume at relatively low intracavernosal pressures. Tunical distensibility VE/VF denoted the maximal erect to flaccid penile volume ratio. The magnitudes of X and VE/VF in the study population were 0.04-0.17 mmHg-1 and 1.7-5.0 respectively. CONCLUSIONS: Enabling penile volume to be derived as a function of tissue mechanical characteristics and pressure, allows for penile rigidity to be expressed (in Part II) as a function of pressure, geometry and tissue qualities.

Adult↗
PubMed1998

Engineering analysis of penile hemodynamic and structural-dynamic relationships: Part II--Clinical implications of penile buckling.

PURPOSE: Penile buckling force was analytically described in terms of its constituents. In addition, theoretically-derived buckling force data were compared to clinically measured data and the influence of each constituent on penile buckling force data was assessed. METHODS: Using engineering buckling theory for a column, a mathematically-derived penile buckling model was developed which incorporated geometric and hemodynamic data obtained by dynamic infusion pharmacocavernosometry studies in 21 impotent patients (age 43, range 24-62 y) as well as penile tissue mechanical characteristics previously developed (Part I). RESULTS: In 17 of 21 patients the mean difference between theoretically derived and clinically measured buckling force data was 0.33 +/- 0.25 kg (r = 0.96). Factors which increased penile buckling forces were: (1) high intracavernosal pressure values (rigidity was related to pressure in an exponential-like fashion); (2) high penile aspect ratio (D/L) values (relatively large diameter/short length penile geometry) and high flaccid diameter; and (3) high cavernosal expandability values (a measure of the ability of the corpora to approach its erect volume with relatively low intracavernosal pressures). CONCLUSIONS: Pressure-volume data (pressure, geometry and tissue characteristics) obtained during erectile function testing have been shown, for the first time, to theoretically predict the magnitude of clinically-measured penile buckling forces.

Adult↗
PubMed1998

Engineering analysis of penile hemodynamic and structural-dynamic relationships: Part III--Clinical considerations of penile hemodynamic and rigidity erectile responses.

PURPOSE: The extent to which hemodynamic erectile responses predict penile buckling forces has not previously been analytically investigated. An engineering study was performed to compare hemodynamic data with penile buckling force values. METHODS: Dynamic infusion pharmacocavernosometry studies in 21 impotent patients (age 43, range 24-62 y) were accomplished to obtain information during penile erection concerning hemodynamic values, penile buckling forces and their determinants: intracavernosal pressure, erectile tissue mechanical properties and penile geometry. RESULTS: In the 21 patients, discrepancies existed in several patients who demonstrated normal hemodynamic values (low flow-to-maintain and high equilibrium intracavernosal pressures) but elevated cavernosal compliance values and diminished penile buckling forces. There was poor correlation between cavernosal compliance and equilibrium intracavernosal pressure (r = -0.36); better correlation between compliance and expandability (r = -0.72) and best correlation between dimensionless compliance and the dimensionless product of expandability with equilibrium pressure (r = -0.88). These data implied that cavernosal compliance was dependent on multiple factors, not only equilibrium intracavernosal pressure. CONCLUSIONS: Hemodynamic indices which correlate with intracavernosal pressure alone do not predict penile buckling forces since the latter are dependent not only on intracavernosal pressure but also on penile geometry and erectile tissue properties. The most relevant tissue property in predicting adequate penile buckling forces is cavernosal expandability. A new impotence classification system and diagnostic algorithm based on the determinants of penile rigidity and not exclusively on hemodynamic responses in proposed.

Adult↗
PubMed1998

Preliminary report on the development and characterization of rabbit clitoral smooth muscle cell culture.

PURPOSE: Scientific model systems for physiological evaluation and investigation of pathophysiologies in clitoral function have been limited. The aim was to develop a New Zealand White rabbit clitoral corpus cavernosum smooth muscle cell culture. METHODS: Clitoral corpus cavernosum erectile tissue was harvested and placed in culture. Clitoral smooth muscle cells which migrated out from explants were grown to confluence and subcultured. Characterizations were performed by morphological and biochemical analyses. RESULTS: The cells exhibited typical morphologic characteristics of smooth muscle cells. Indirect immunofluorescence studies confirmed the presence of a-smooth muscle cell actin. Androgen and estrogen receptors were detected by specific antibodies and binding studies. The cells expressed subtypes of TGF-beta receptors. Treatment with 80 pM TGF-beta 1 24 h resulted in induction and/or increased availability of TGF-beta receptors. CONCLUSIONS: An in-vitro cell culture system using rabbit clitoral smooth muscle cells was developed. These smooth muscle cells retain their biochemical and functional integrity. This in-vitro cell culture system may facilitate studies aimed at understanding the molecular basis of female sexual function.

Animals↗