Characterisation of pomegranate juice effects on human corpus cavernosum.

Pomegranate (POM) juice may benefit the erectile process, but the scientific evidence is lacking. This study evaluates the molecular characterisation and confirmation of POM's action on human corpus cavernosum (HCC) obtained from patients (n = 16) undergoing penile prosthesis implantation. After phenylephrine contraction, the relaxant effects of POM with various inhibitors in the presence and absence of palmitic acid (PA)-induced acute oxidative stress were investigated. Electrical field stimulation (EFS)- and acetylcholine (ACh)-induced relaxation were performed using organ bath preparation. Expression of neuronal nitric oxide synthase (nNOS), endothelial (eNOS), phosphodiesterase (PDE)-5A and cGMP levels were assessed in cells from ex vivo organ cultures of HCC, using RT-PCR, ELISA and immunohistochemistry techniques. POM induced marked relaxation of HCC (maximum response: 97.0 ± 3.1%) and reversed the PA-induced decrease of EFS (20 Hz). nNOS transcription was increased by 7-fold in POM-treated cells without influencing eNOS and PDE5A expressions. We conclude that POM induced marked relaxation of HCC via: (i) nNOS stimulation, and (ii) downstream relaxation stimulated by nNOS and cGMP and bypassing the NO and PDE5. This action provides a rationale for the therapeutic or preventative use of POM in men with erectile dysfunction who do not respond well to PDE5 inhibitors.

Effect of avanafil on rat and human corpus cavernosum.

We compared the activity of a new phosphodiesterase-5 inhibitor (PDE5i) avanafil with sildenafil and tadalafil in human and rat corpus cavernosum (CC) tissues. The effect of avanafil with several inhibitors and electrical field stimulation (EFS) was evaluated on CC after pre-contraction with phenylephrine. With the PDE5i, sildenafil and tadalafil, concentration-response curves were obtained and cyclic guanosine monophosphate (cGMP) levels were measured in tissues. Avanafil induced relaxation with maximum response of 74 ± 5% in human CC. This response was attenuated by NOS inhibitor and soluble guanylate cyclase (sGC) inhibitor. Avanafil potentiated relaxation responses to acetylcholine and EFS in human CC and enhanced SNP-induced relaxation and showed 3-fold increase in cGMP levels. When compared with sildenafil, avanafil and tadalafil were effective at lower concentrations in human CC. In addition, Sprague-Dawley rats underwent in vivo intracavernosal pressure (ICP) and mean arterial pressure (MAP) measurements. Avanafil increased ICP/MAP that was enhanced by SNP and cavernous nerve (CN) stimulation in rat CC tissues. Also avanafil showed maximum relaxation response of 83 ± 7% in rat CC with 3-fold increase in cGMP concentration. Taken together, these results of our in vivo and in vitro studies in human and rat suggest that avanafil promotes the CC relaxation and penile erection via NO-cGMP pathway.

Understanding the course of Peyronie's disease.

AIMS: To correct common misconceptions about Peyronie's disease (PD) that present obstacles to early recognition and treatment. METHODS: The prevalence, natural disease course, psychosocial effects and treatment considerations for patients with PD were reviewed. RESULTS: Studies over the past decade have shown that the prevalence of PD may be higher (up to 20%) than previously thought. PD can lead to emotional and relationship distress. Nearly 10% of men who present with PD are younger than 40. Both younger age and comorbid vascular disease have been associated with more severe and progressive PD. In the majority of patients, symptoms will either deteriorate or remain stable. PD is often associated with erectile dysfunction (ED). Effective, minimally invasive treatments used early in the disease course include unapproved and/or investigational intralesional injection therapy with verapamil, interferon (IFN) α-2b, or collagenase clostridium histolyticum (CCH). Surgical intervention is considered in patients with ED and/or penile deformity that impairs sexual functioning; however, preoperative discussion of appropriate expectations is important. DISCUSSION: The availability of effective minimally invasive and surgical therapies for PD suggests that active management should be considered over a 'wait-and-see' approach. CONCLUSION: Providing early intervention and improved education/awareness of PD as a chronic and progressive disorder may result in improved physical and psychosocial outcomes for PD patients. As general practitioners are often the first contact for men with PD, they are well positioned to recognise symptoms early and promptly refer patients for further evaluation and treatment.

Update on treatments for premature ejaculation.

Current and upcoming treatment options for premature ejaculation (PE) are of global clinical interest. In 2008, the International Society for Sexual Medicine published an evidence-based definition for PE. While there are no US Food and Drug Administration-approved therapies for PE, the American Urological Association 2004 guidelines state the serotonergic antidepressants paroxetine, sertraline, fluoxetine and clomipramine and the topical lidocaine-prilocaine cream are effective treatment options. However, there are limitations associated with their use, which may be overcome by PE-specific therapies currently in development. Two agents that are in advanced stages of clinical development include: (i) dapoxetine, an on-demand short-acting selective serotonin reuptake inhibitor, and (ii) PSD502, a metered-dose aerosol containing lidocaine and prilocaine, also for on-demand treatment. Another on-demand agent in development is tramadol, a weak opioid that is currently approved for treating pain. Coupled with efficient diagnosis, it is hoped that these newer agents will improve the quality of life for patients who suffer from PE.

Survey of patient and partner satisfaction following collagenase Clostridium histolyticum treatment for Peyronie's disease.

Intralesional injection of collagenase Clostridium histolyticum (CCH) is a minimally invasive, Food and Drug Administration-approved, effective treatment for Peyronie's disease (PD). To assess the satisfaction of patients and their female sexual partners (FSP) following CCH therapy for PD, we conducted a retrospective review of the records of all patients treated with CCH for PD between 04/2014 and 03/2016. Collected variables included demographics, pre- and post-treatment sexual function, penile curvature, penile vascular findings, and treatment outcomes. Patients and their FSPs were subsequently contacted by telephone and queried regarding their ability to have intercourse and their satisfaction with treatment. A total of 24 couples responded to our questionnaire and constitute the subjects of this analysis. Patient and FSP satisfaction with treatment were 67% and 71%, respectively. Significant predictors of FSP satisfaction with treatment included recall of penile trauma during prior sexual intercourse, improved ability to have sexual intercourse following treatment, and absence of post-procedural glans hypoesthesia. In conclusion, CCH imparts a significant benefit on a couple's sexual health. Partner satisfaction with treatment is correlated with improved ability to have sexual intercourse and absence of patient glans hypoesthesia.

Gene and stem cell therapy for erectile dysfunction.

Erectile dysfunction (ED) is defined as the inability to attain and/or maintain penile erection sufficient for satisfactory sexual performance. ED is a highly prevalent health problem with considerable impact on the quality of life of men and their partners. Although the treatment of ED with oral phosphodiesterase type V (PDE5) inhibitors is effective in a wide range of individuals, it is not efficacious in all patients. The failure of PDE5 inhibitors happens mainly in men with diabetes, non-nerve sparing radical prostatectomy, and high disease severity. Therefore, improved therapies based on a better understanding of the fundamental issues in erectile physiology and pathophysiology have recently been proposed. Here, we summarize studies on ED treatment using gene and stem cell therapies. Adenoviral-mediated intracavernosal transfer of therapeutic genes, such as endothelial nitric oxide synthase (eNOS), calcitonin gene-related peptide (CGRP), superoxide dismutase (SOD), and RhoA/Rho kinase and mesenchymal stem cell-based cell and gene therapy strategy for the treatment of age- and diabetes-related ED are the focus of this review.

Erectile dysfunction in urethral stricture and pelvic fracture urethral injury patients: diagnosis, treatment, and outcomes.

Urethral stricture disease, pelvic fracture urethral injury (PFUI), and their various treatment options are associated with erectile dysfunction (ED). The etiology of urethral stricture disease is multifactorial and includes trauma, inflammatory, and iatrogenic causes. Posterior urethral injuries are commonly associated with pelvic fractures. There is a spectrum in the severity of both conditions and this directly impacts the treatment options offered by the surgeon. Many published studies focus on the treatment outcomes and the relatively high recurrence rates after surgical repair. This communication reviews the current knowledge of the association between ED and urethral stricture disease, as well as PFUI. The incidence, pathophysiology, and clinical ramifications of both conditions on sexual function are discussed. The treatment options for ED in those patients are reviewed and summarized.

Comparison of infrapubic versus transcrotal approaches for inflatable penile prosthesis placement: a multi-institution report.

Inflatable penile prostheses (IPP) are associated with excellent long-term outcomes. To date, no study has evaluated the significance of surgical approach on IPP intraoperative variables. High-volume surgeons placing the Titan 0-degree prosthesis from March-July 2012 completed questionnaires including pre-/intraoperative variables. Intraoperative data were compared between surgeons performing an infrapubic versus transcrotal approach for total length of prosthesis, proximal and distal measurements, rear-tip extender (RTE) length, reservoir size and fill volume and ability to place the reservoir in the space of Retzius. Forty-six surgeons placed 256 IPPs, with a median of 5 (range 1-10) inserted. Transcrotal placement was performed most commonly (80%). Revision procedures accounted for 13% of cases, with 19% previously undergoing robotic-assisted prostatectomy. Compared with infrapubic, transcrotal placement resulted in a longer total prosthesis (22.3 cm vs 20.6 cm, P < 0.0001), increased proximal dilation (10.1 cm vs 8.6 cm, P < 0.0001), longer RTEs (1.9 cm vs 1.2 cm, P < 0.0001) and larger reservoir fill volume (79 cc vs 71 cc, P = 0.0003). No differences were noted in distal measurements or ability to place the reservoir in the space of Retzius. Compared with the infrapubic approach, high-volume surgeons placing the Titan 0-degree IPP transcrotally achieved increased proximal dilation with an ~1-2-cm-longer prosthesis inserted.

Therapeutic advances in the treatment of Peyronie's disease.

Peyronie's disease (PD) is an under-diagnosed condition with prevalence in the male population as high as 9%. It is a localized connective tissue disorder of the penis characterized by scarring of the tunica albuginea. Its pathophysiology, however, remains incompletely elucidated. For the management of the acute phase of PD, there are currently numerous available oral drugs, but the scientific evidence for their use is weak. In terms of intralesional injections, collagenase clostridium histolyticum is currently the only Food and Drug Administration-approved drug for the management of patients with PD and a palpable plaque with dorsal or dorsolateral curvature >30°. Other available intralesional injectable drugs include verapamil and interferon-alpha-2B, however, their use is considered off-label. Iontophoresis, shockwave therapy, and radiation therapy have also been described with unconvincing results, and as such, their use is currently not recommended. Traction therapy, as part of a multimodal approach, is an underused additional tool for the prevention of PD-associated loss of penile length, but its efficacy is dependent on patient compliance. Surgical therapy remains the gold standard for patients in the chronic phase of the disease. In patients with adequate erectile function, tunical plication and/or incision/partial excision and grafting can be offered, depending on degree of curvature and/or presence of destabilizing deformity. In patients with erectile dysfunction non-responsive to oral therapy, insertion of an inflatable penile prosthesis with or without straightening procedures should be offered.

The direction and severity of penile curvature does not have an impact on concomitant vasculogenic erectile dysfunction in patients with Peyronie's disease.

Although the association between Peyronie's disease (PD) and erectile dysfunction (ED) is well established, limited data are available correlating penile curvature and penile hemodynamic parameters. We sought to examine this association in a cohort of PD men undergoing penile duplex Doppler ultrasound (PDDU). PD patients were retrospectively evaluated to correlate the extent and direction of penile curvature with measured vascular parameters. Demographic variables, disease characteristics and PDDU parameters were tabulated and statistically compared based on extent (≤ 45° and >45°) and direction (dorsal, ventral, lateral, ventrolateral, dorsolateral) of curvature. A total of 220 PD patients (mean age of 55.0 ± 9.2 years) underwent PDDU at one institution from January 2008 to December 2010. Overall, 69.5% of patients were found to have vasculogenic ED (arterial insufficiency (AI): 10%; veno-occlusive dysfunction (VOD): 43.2%; AI + VOD: 16.4%). Mean curvature was similar among all PDDU groups (AI: 41.7 ± 5.2°; VOD: 41.3 ± 2.5°; AI+VOD: 37 ± 4.1°; no-ED: 37.3 ± 3°; P > 0.85). No significant differences were noted in the presence or type of ED among various directions of curvature (P = 0.34) or when curvatures were stratified by ≤ 45° and >45°. The direction and extent of penile curvature are not associated with altered rates of vasculogenic ED on PDDU in PD patients.

Failure to attain stretched penile length after intracavernosal injection of a vasodilator agent is predictive of veno-occlusive dysfunction on penile duplex Doppler ultrasonography.

Penile duplex Doppler ultrasound (PDDU) assesses the etiology of erectile dysfunction. Peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI) are common PDDU parameters. We assessed whether stretched penile length (SPL) in the flaccid state and measured penile length at peak erection after intracavernosal injection (ICI) of a vasodilator during PDDU correlated with the etiology of erectile dysfunction. We performed a retrospective review of 93 patients who underwent PDDU for erectile dysfunction. Normal and stretched penile length were measured, both at a flaccid state prior to ICI and at peak erection during PDDU. Collected data included patient demographics, vascular, and anatomic parameters. The mean age was 52 years. SPL was equivalent to peak penile length after ICI in 60 patients (65%, group 1) and did not match in 33 (35%, group 2). There were no significant differences between the two groups in terms of flaccid, stretched, and post-ICI erect penile lengths, IIEF score, PSV, percent rigidity or tumescence, and vasodilator dose used. Patients in group 2 had less of a change in penile length from flaccid to erect state (36% vs. 44%, p = 0.02), higher EDV (12.0 vs. 8.5, p = 0.041), lower RI (0.6 vs. 1.0, p = 0.046), and more veno-occlusive dysfunction (82% vs. 53%, p = 0.001). On multivariate analysis, failure to reach maximum SPL at peak ICI erection (OR 2.255, CI 1.191-4.271, p = 0.0126), EDV (OR 1.281, CI 1.115-1.471, p < 0.001) and RI (OR 0.694, CI 0.573-0.723, p = 0.009) predicted veno-occlusive dysfunction. Failure to reach maximal SPL during PDDU using ICI with a vasodilator agent predicted veno-occlusive dysfunction, which is independent of both penile rigidity and tumescence. This measurement could serve as another diagnostic tool for predicting veno-occlusive dysfunction when PDDU is not readily available. Limitations include the subjective nature of penile measurements and different PGE1 doses used.

Differential expression of novel biomarkers (TLR-2, TLR-4, COX-2, and Nrf-2) of inflammation and oxidative stress in semen of leukocytospermia patients.

Chronic genitourinary inflammation results in Leukocytospermia (LCS), an elevated number of white blood cells (WBCs) in semen, which, in association with oxidative stress, may suppress sperm function, and manifest as male factor infertility. The current clinical diagnosis of LCS employs manual enumeration of WBCs and requires complex staining and laboratory skills or measurement of inflammatory cytokines and chemokines levels. Many patients with idiopathic infertility are asymptomatic. In search of better inflammatory markers for LCS, we evaluated expression of toll-like receptors 2 and 4 (TLR-2/4), cyclooxygenase-2 (COX-2), and nuclear factor (erythroid-derived 2)-like 2 (Nrf-2) in semen samples of age-matched infertile patients with and without LCS. We employed the usage of specific Western blot evaluation, cytokine array; immunofluorescence microscopy (IFM) followed by computer-based analysis, and other molecular approaches. As compared with non-LCS patients (n = 38), semen samples from LCS patients (n = 47) displayed significantly lower total sperm count (p < 0.01), motility (p < 0.0001), normal head count (p < 0.0001), and a significantly higher white blood cell count (p < 0.0001). Differential cytokine profiling of seminal plasma by antibody array revealed up-regulation of several pro-inflammatory chemokines in LCS samples. Western blot analysis of LCS seminal plasma (n = 15) also showed a significant increase in expression of TLR-2 (p < 0.001) and 4 (p < 0.01), COX-2 (p < 0.001), and Nrf-2 (p < 0.001) as compared with semen samples from non-LCS patients (n = 15). Computer-based objective IFM analysis of spermatozoa from LCS patients showed increased expression of TLR-4 (p < 0.001), Cox-2 (p < 0.01), and (Nrf-2) (p < 0.01). Significant differences in the subcellular localization of these proteins were evident in the sperm head and tail segments of LCS samples. Altogether, these observations suggest that TLR-2/4, COX-2, and Nrf-2 can serve as novel biomarkers of inflammation and oxidative stress. Therefore, developing a rapid assay for these biomarkers may facilitate early diagnosis and management of LCS especially in idiopathic and asymptomatic male infertility patients.

History, epidemiology, and clinical presentation of Peyronie's disease.

Peyronie's disease is a localized connective tissue disorder that involves the tunica albuginea of the penis. The formation of fibrotic plaques in the tunica albuginea and surrounding cavernosal tissue alters penile anatomy and can cause different degrees of bending and narrowing, as well as penile pain and erectile dysfunction. Although long recognized as an important clinical entity of the male genitalia, the etiology of this disease has remained poorly understood. Recent studies have demonstrated that this disorder may be more prevalent than previously reported. The following review will examine the history, epidemiology, and clinical presentation of Peyronie's disease.

Three-piece inflatable penile prosthesis components (surgical pearls on reservoirs, pumps, and rear-tip extenders).

Erectile dysfunction (ED) is a major quality-of-life disorder that affects greater than 30 million American men each year. Since the introduction of Viagra, more and more men are presenting with ED that is not responding to oral or local therapies. Penile prosthesis implantation is recognized as the most effective, although most invasive, ED therapy with a high satisfaction rate. With an aging population both aware of and requesting therapy for ED, the number of penile prosthesis implantations will remain stable, especially at centers specializing in ED treatment. Therefore, a better understanding of the techniques used for placement of the penile prosthesis is necessary. The following review will discuss the techniques and a few clinical pearls in the placements of inflatable penile prostheses.

Surgical approaches for advanced Peyronie's disease patients.

Surgical therapy for Peyronie's disease (PD) is reserved for patients with severe penile deformity that fails to improve with medical treatment and impedes sexual intercourse. The surgical treatment of PD consists of either correction of the penile deformity or insertion of a penile prosthesis in patients with concomitant erectile dysfunction (ED). Plaque incision/excision combined with grafting procedures or plication techniques are suitable in Peyronie's patients having an adequate penile vascular supply. When patients with Peyronie's disease have both penile deformity and ED, penile prosthesis implantation with or without excision or incision of the tunica is the current standard of care.

Intralesional interferon-alpha-2b for the treatment of Peyronie's disease.

Peyronie's disease can best be described as a localized connective tissue disorder that primarily affects the tunica albuginea of the penis. The disease may be attributed to repetitive vascular trauma that initiates an inflammatory process and ultimately leads to the formation of a fibrous penile plaque. The plaque consists mainly of collagen and can significantly alter penile anatomy and function. Patients with Peyronie's disease will most often present with penile curvature, pain on erection, a palpable nodule most commonly located on the dorsal shaft of the penis, and erectile dysfunction. There is no definitive treatment for Peyronie's disease and the treating physician has many options. They may wait for spontaneous resolution of the plaque, choose medical therapy (which includes both oral and intralesional regimens), or opt for surgical management. The main purpose of this article is to discuss the advances in medical therapy for Peyronie's disease, in particular intralesional injection of interferon-alpha-2b (IFN-alpha-2b). Several studies have concluded that IFN-alpha-2b can be an effective modality of treatment and that many patients placed on a regimen of IFN-alpha-2b experienced a significant reduction in penile curvature, diminished pain with erection, and decreased size of the plaque. Further clinical studies are currently being undertaken to determine the precise quantity and frequency of administration of IFN-alpha-2b that is most effective with the least amount of side effects.

Implications of nitric oxide synthase isoforms in the pathophysiology of Peyronie's disease.

Peyronie's disease is an idiopathic, localized connective tissue disorder of the penis which involves the tunica albuginea of the corpus cavernosum and the adjacent areolar space. Peyronie's disease is characterized by local changes in the collagen and elastic fiber composition of the tunica albuginea. The formation of fibrotic plaques alters penile anatomy and can cause different degrees of bending and narrowing, as well as penile pain and erectile dysfunction. Though long recognized as an important clinical entity of the male genitalia, the etiology of this disease has remained poorly understood. Until recently there have been no studies to examine the role nitric oxide (NO) and nitric oxide synthase (NOS) isoforms may play in the onset and progression of Peyronie's disease. NO is a potent biological mediator with diverse physiological and pathophysiological roles. The purpose of this review is to describe each of the NOS isoforms and their potential roles in the pathophysiology of Peyronie's disease, with particular emphasis on the regulation of endothelial and inducible NOS isoforms.

Feline penile erection induced by topical glans penis application of combination alprostadil and SEPA (Topiglan).

The objective of this study was to evaluate the efficacy of topically applied prostaglandin E1 (PGE(1))+5% SEPA (soft enhancement of percutaneous absorption) on the glans penis in a feline erection model. Erectile response after glans penis administration of PGE(1)+5% SEPA cream (Topiglan, MacroChem Co., Lexington, MA, USA) was compared to the erectile response after intracavernosal administration of the triple-drug combination (1.65 mg papaverine, 25 microg phentolamine, and 0.5 microg PGE(1)). The placebo cream and increasing concentrations (0.25%, 2.5 mg/ml; 0.5%, 5 mg/ml; and 1%, 10 mg/ml) of PGE(1)+5% SEPA were applied in a total volume of 0.1 ml via a plastic needle-less syringe. The control triple-drug combination was administrated intracavernosally via a 30-gauge needle at the completion of each experiment to serve as a control reference. With each application of placebo, PGE(1)+SEPA, and the triple-drug combination, changes in intracavernosal pressure and systemic blood pressure were continuously monitored. Topical application of PGE(1)+SEPA induced increases in intracavernosal pressure in a dose-dependent manner, with minimal effects on systemic blood pressure. The increases obtained with 1% PGE(1) Topiglan cream were similar to the intracavernosal pressure values elicited by the standard intracavernosal triple-drug combination. These data demonstrate that topical glans penis application of PGE(1)+SEPA can induce an erectile response in cats with minimal systemic adverse effects. Oral pharmacological agents are the first-line treatment for male ED. Studies investigating the effectiveness of noninvasive modalities such as topical therapy should continue, because these agents have the potential to avoid the systemic effects commonly seen with oral therapies. Additionally, topical therapy may also benefit patients who are unresponsive to oral agents or have explicit contraindications. Topical PGE(1) application to the glans penis may become an important treatment option in selected patients suffering from erectile dysfunction.

Effect of combination endothelial nitric oxide synthase gene therapy and sildenafil on erectile function in diabetic rats.

Erectile dysfunction associated with diabetes mellitus is caused in part by disordered endothelial smooth muscle relaxation, neuropathy, and a decrease in cavernosal nitric oxide synthase (NOS) activity. The purpose of this study was to determine whether a combination of sildenafil and adenoviral gene transfer of endothelial NOS (eNOS) could enhance the erectile response in diabetic rats. Five groups of animals were utilized: (1) age-matched control rats, (2) streptozotocin (STZ)-induced diabetic rats (60 mg/kg i.p.), (3) STZ-rats + sildenafil (2 mg/kg i.v.), (4) STZ-rats transfected with AdCMVbetagal or AdCMVeNOS, and (5) STZ-rats transfected with AdCMVeNOS +sildenafil (2 mg/kg i.v.). At 2 months after i.p. injection of STZ, groups 4 and 5 were transfected with the adenoviruses and 1-2 days after transfection, all animals underwent cavernosal nerve stimulation (CNS) to assess erectile function. Cyclic 3',5'-guanosine monophosphate (cGMP) levels were assessed in the cavernosal tissue. STZ-diabetic rats had a significant decrease in erectile function as determined by the peak intracavernosal pressure (ICP) and total ICP (area under the erectile curve; AUC) after CNS when compared to control rats. STZ-diabetic rats+AdCMVeNOS had a peak ICP and AUC, which were similar to control animals. STZ-diabetic rats administered sildenafil demonstrated a significant increase in peak ICP at the 5 and 7.5 V settings, while the AUC was significantly increased at all voltage (V) settings. The increase in both ICP and AUC of STZ-diabetic rats transfected with AdCMVeNOS at all V settings was greater than STZ-diabetic rats transfected with AdCMVbetagal. STZ-diabetic rats transfected with AdCMVeNOS and administered sildenafil had a significant increase in total ICP that was greater than eNOS gene therapy alone. Cavernosal cGMP levels were significantly decreased in STZ-diabetic rats, but were increased after transfection with AdCMVeNOS to values greater than control animals. In conclusion, overexpression of eNOS and cGMP in combination with sildenafil significantly increased both the peak ICP and total ICP to CNS in the STZ-diabetic rat, which was similar to the response observed in control rats. Moreover, the total erectile response was greater in STZ-diabetic rats receiving eNOS gene therapy plus sildenafil than STZ-rats receiving sildenafil or eNOS gene therapy alone.