Reperfusion of ischemic corporal tissue: physiologic and biochemical changes in an animal model of ischemic priapism

Ischemic priapism caused by self intracavernous injection of tadalafil

Introduction

We present a case of ischemic priapism caused by self intracavernous injection of tadalafil.

Case presentation

A 77-year-old man developed priapism due to self-injection of tadalafil into the corpus cavernosum. He presented to our hospital 2 days after the development of priapism and severe penile pain. The blood gas analysis of the corpus cavernosum revealed ischemic priapism. At first, we performed percutaneous distal shunt (T-shunt) and cavernosal irrigation, resulting in slight improvement of penile tumescence. Several hours later, penile tumescence and severe pain reappeared. Bilateral proximal (corpora-spongiosal) shunt was performed under anesthesia again. Penile tumescence was slowly and gradually relieved. His erectile function was declined.

Conclusion

We experienced a case of priapism due to self intracavernous administration of tadalafil who needed a proximal shunt to relieve the severe penile pain. This case report may serve as a warning for physicians and patients not to use phosphodiesterase 5 inhibitor inappropriately.

The role of angiotensin receptor blocker (losartan) on decreasing fibrotic process of corpora cavernosa in priapism model of wistar rats

Background

Priapism induces regulation of Transforming Growth Factor-β1 (TGF-β1) expression and collagen-type-1 deposition. This will replace the normal corpora cavernosa with fibrotic tissue which eventually resulted in erectile dysfunction. It is also known that the fibrosis process of corpora cavernosa is related to Renin-Angiotensin II System (RAS). Angiotensin II receptor blockers (ARB), especially losartan, inhibit the inflammation process and fibrotic tissue formation. This study evaluated the effect of losartan in reducing fibrosis in priapism by evaluating TGF-β1 and collagen-type-1 in cavernous tissue and determined the effect of losartan in preventing fibrosis in priapism model of Wistar rats assessed by the metavir score.

Methods

A total of eighteen male Wistar rats mean were divided into five groups. For the priapism models, we applied negative pressure on the penis to make an artificial erection to mimic the priapism process. The control groups were observed and the treatment groups were orally given losartan 15 mg/kg/day. Corpora cavernosa was harvested for TGF-β1 and collagen-type-1 measurement using an enzyme-linked immunosorbent assay (ELISA). The fibrotic tissue of each rat was then collected and assessed histopathologically with the metavir scoring system.

Results

Penile TGF-β1 concentration in the losartan-treated group was not significantly different on day 10 and day 28 of observation (p10=0,30; p28=0,17). Meanwhile, collagen-type-1 concentration was significantly lower compared to control group (p10=0,002; p28=0,01). There was a significant difference in metavir scores in rats that received losartan and those who did not (p<0,05).

Conclusion

Losartan could suppress the fibrosis process in the priapism model. It could decrease the collagen type 1 deposition during corpora cavernosa tissue regeneration. Based on the metavir score, the group receiving losartan therapy was better than the control group.

An Experimental Rat Model Study: Is There Any Effect of Syringic Acid on Ischemia-Reperfusion Injury in Priapism?

Purpose The purpose of this research is to examine the impact of syringic acid on ischemia-reperfusion injury in cavernosal tissue, utilizing a rat model of induced priapism. Materials and methods A total of 24 rats were allocated into three groups. Group 1 was designated as the control group, while Group 2 underwent ischemia-reperfusion injury assessment using the priapism model. Group 3 underwent the same procedures as Group 2, with the addition of intraperitoneal administration of syringic acid (100 mg/kg) 60 min after priapism initiation. All rats underwent penectomy, and sufficient blood samples were collected. Histopathological assessment of penile cavernosal tissue involved grading tissue damage, inflammation, vasocongestion, desquamation, and edema on a scale of 0-3 (0: normal, 1: mild, 2: moderate, 3: severe). Result Significant differences were observed among the three groups in terms of IL-1 beta and TNF-alpha levels (p=0.001 and p<0.001, respectively). IL-1 beta and TNF-alpha levels in Group 2 were found to be significantly higher than Group 3 (p=0.003 and p=0.004). There was also a significant difference among the three groups in terms of median MDA levels (p<0.001). Furthermore, the median MDA level in Group 2 was found to be significantly higher than that in Group 3 (p<0.001). While significant differences were observed among the three groups in terms of median SOD and GSH-px levels, no significant difference was found among the groups in terms of median PC levels (p=0.004, p= 0.048, and p=0.159, respectively). In direct microscopic examination, a significant improvement in pathological scores was noted in Group 3 compared to Group 2 (p<0.001). Conclusion Syringic acid demonstrated protective properties against ischemia-reperfusion injury caused by priapism in cavernosal tissue.

Review of Ischemic and Non-ischemic Priapism

PURPOSE OF REVIEW

Priapism is a rare condition that has different presentations, etiologies, pathophysiology, and treatment algorithms. It can be associated with significant patient distress and sexual dysfunction. We aim to examine the most up-to-date literature and guidelines in the management of this condition.

RECENT FINDINGS

Priapism is a challenging condition to manage for urologists, since the etiology is often multi-factorial and the suggested treatment algorithms are based on small studies and expert anecdotal experience, perhaps due to the rarity of the disorder. Ischemic priapism of less than 24 h can be managed non-surgically in most cases with excellent results. Ischemic priapism of more than 36 h is frequently associated with permanent erectile dysfunction. Management of prolonged priapism with penile shunting still may result in poor erectile function, so penile prosthesis can be discussed in these scenarios.

Protective effects of dexmedetomidine on ischaemia-reperfusion injury in an experimental rat model of priapism

The study aimed to investigate the effects of dexmedetomidine against ischaemia-reperfusion injury occurring after priapism in a model of induced-priapism in rats. A total of 18 male rats were randomised into three groups. Group 1 was the control group. A priapism model was performed rats in Group 2 and then ischaemia-reperfusion injury was evaluated. Group 3 had similar procedures to the rats in Group 2. Rats in Group 3 additionally had 100 μg/kg dexmedetomidine administered intraperitoneally immediately after reperfusion. Blood and tissue samples were analysed. Biochemical analysis of blood samples revealed a decrease in the levels of the pro-inflammatory cytokines including interleukin-1 beta (IL-1 Beta), interleukin-6 (IL-6), and tumour necrosis factor-alpha (TNF-alpha) in Group 3 compared to Group 2 (p:.04, p:.009 and p:.009, respectively). Similarly, the highest malondialdehyde (MDA) level was in Group 2 (p:.002). The levels of antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were significantly higher in Group 3 than that of Group 2 (p:.037 and p:.045, respectively). Direct microscopic examinations revealed positive changes in desquamation, oedema, inflammation and vasocongestion scores in Group 3 compared to Group 2 (p:.007, p:.008, p:.007 and p:.006, respectively). Dexmedetomidine has a protective effect against ischaemia-reperfusion injury in penile tissue.

Neurobehavioral, testicular and erectile impairments of chronic ketamine administration: Pathogenesis and ameliorating effect of N-acetyl cysteine

Ketamine, a dissociative anesthetic, recently has spread as a recreational drug. Its abuse lead to neurobehavioral disturbance in addition to toxic effects on other body organs. To evaluate the toxic effects of chronic administration of low ketamine doses on the memory, testicles, and erection, explore its pathophysiology through oxidative stress mechanism and examine the ameliorating effect of N-acetyl cysteine (NAC). A total of 40 male albino rats were assigned to control, vehicle, ketamine only I.P. (10 mg/kg), and ketamine (10 mg/kg) + NAC (150 mg/kg) groups. Assessment of memory affection and erectile function by Passive Avoidance, Novel Object Recognition, and copulatory tests were performed. Estimation of malondialdehyde (MDA), catalase (CAT), and total antioxidant capacity (TAC) in serum and prefrontal & hippocampal homogenate, and luteinizing hormone (LH), testosterone in serum were done. Prefrontal cortex, hippocampus, and testes were collected for histopathology. Chronic ketamine administration induced significant memory deficits (P < 0.05), reduced erectile function (P < 0.05), severe hypospermatogenesis, increased MDA, reduced CAT, TAC levels in serum, and tissue homogenate (P < 0.05) and reduction of LH, and testosterone (P < 0.05). Treatment with NAC resulted in significant improvement of memory function, improved erectile function, and decrease in oxidative injury in both serum and tissue homogenates. Testosterone and LH levels exhibited significant difference between treatment groups and controls (P < 0.05). NAC reduced the deleterious histopathological changes. These data suggest that long-term ketamine affects short and long memory, induces erectile and testicular dysfunction through oxidative stress. Co-administration with NAC ameliorates these toxic effects.

Effect of Intracorporeal Human Adipose-Derived Stem Cells (hADSCs) on Corpora Cavernosa Transforming Growth Factor β1 (TGFβ1) and Collagen Type I Concentration in Wistar Rat Priapism Model

Introduction

The ischemic process in priapism can lead to displacement of normal tissue with fibrotic tissue, due to collagen deposition, and eventually leads to erectile dysfunction. Many studies have identified that the supernatant of adipose tissue–derived stem cells (ADSCs) significantly ameliorates fibrosis of different tissue, but limited attention has been paid to its efficacy on fibrosis of the corpora cavernosa.

Methods

A total of 22 Wistar rats divided into five groups, with two groups each consisting of five male wistar rats with priapism without human ADSC (hADSC) therapy (group I) and two other groups consisting of five rats with priapism, were given 10⁶ cells' intracorporeal hADSC injection after 12 hours of penile clamping (group II) were euthanized after 2 and 4 weeks of observation. The last group consisted of two rats without any treatment or model (group III). Following euthanasia, penises were harvested for TGFβ₁ and collagen type I measurement using ELISA. Statistical analysis using independent-sample t-tests was done with SPSS 21.0.

Results

Penile TGFβ₁ concentration in the treatment group was significantly lower in the second and fourth weeks of observation (p₂=0.004, p₄=0.003), and collagen type I was significantly lower in the second and fourth weeks (p₂=0.003, p₄=0.011).

Conclusion

Intracorporeal hADSC injection limited the fibrosis process in a priapism model. Although the mechanism was unclear, it may be related to the potential of hADSCs to produce various growth factors that could limit TGFβ₁ and collagen production.

Ischemic priapism as a model of exhausted metabolism

In vivo metabolic studies typically concern complex open systems. However, a closed system allows better assessment of the metabolic limits. Ischemic priapism (IP) constitutes a special model of the compartment syndrome that allows direct sampling from a relatively large blood compartment formed by the corpora cavernosa (CC). The purpose of our study was to measure metabolic changes and the accumulation of end products within the CC during IP. Blood gas and biochemical analyses of aspirates of the CC were analyzed over an 8-year period. Mean ± SD pH, pCO2 , pO2 , O2 -saturation, lactate, and glucose of the aspirated blood were determined with a point-of-care analyzer. Forty-seven initial samples from 21 patients had a pH of 6.91 ± 0.16, pCO2 of 15.3 ± 4.4 kPa, pO2 of 2.4 ± 2.0 kPa, and an O2 -saturation of 19 ± 24% indicating severe hypoxia with severe combined respiratory and metabolic acidosis. Glucose and lactate levels were 1.1 ± 1.5 and 14.6 ± 4.8 mmol/L, respectively. pH and pCO2 were inversely correlated (R2  = 0.86; P < 0.001), glucose and O2 -saturation were positively correlated (R2  = 0.83; P < 0.001), and glucose and lactate were inversely correlated (R2  = 0.72; P < 0.001). The positive correlation of CO2 and lactate (R2  = 0.69; P < 0.001) was similar to that observed in vitro, when blood was titrated with lactic acid. The observed combined acidosis underscores that IP behaves as a closed system where severe hypoxia and glycopenia coexist, indicating that virtually all energy reserves have been consumed.

Current practice in the management of ischemic priapism: an anonymous survey of ISSM members

Penile shunting is the standard of care in management of ischemic priapism refractory (IPR) to non-surgical interventions. Due to high rates of impotence, corporal fibrosis, and loss of penile length, recent literature suggests these patients benefit from immediate penile prosthesis (PP) placement. An IRB-exempt anonymous electronic survey of the 2168 members of the International Society for Sexual Medicine (ISSM) was conducted. The survey included demographic information, confidence, and experience-related management of IPR. The aim was to evaluate current practice patterns in management of IPR and to investigate the role of immediate PP implantation in the management of prolonged (>36 h) IPR. The survey response rate was 11.6% (n = 251). Most respondents were urologists (173), from the USA (49.1%), and had completed a fellowship in male sexual medicine, men's health, reconstruction, or andrology (71.1%). The majority (91.3%) see at least one case of prolonged priapism (>36 h) that requires surgical management yearly. When looking at volume in training and after, our respondents had a significantly higher experience with penile prostheses (over 70%, > = 10) as compared with shunts (less than 40%, > = 10). Overall, 70.9% of respondents felt more comfortable with a malleable PP than a shunt. However, penile shunts are still preferred as the first line of surgical management by ~80% of respondents as compared with 12.7% who instead prefer a PP. We also found that under 40% of respondents currently use penile MRI or corporal biopsies in their management of prolonged assessment. This is the first study to assess current clinical practices in management of IPR globally. As in any anonymous self-reported survey-based research, recall and sampling bias are an inherent limitation. Penile shunting for IPR continues to be the preferred treatment despite emerging data. Respondents performed PP surgery routinely and feel more confident placing PP than performing penile shunting procedures.

The effects of oxytocin on penile tissues in experimental priapism model in rats

PURPOSE

This study aimed to demonstrate the effects of oxytocin on penile tissues in ischemia-reperfusion injury developed after priapism.

METHODS

Forty Wistar Albino strain male rats were divided into four groups. The control group (n = 10) was not intervened. In Group 2, a rat model of priapism was constructed and maintained for 1 h. In Group 3, reperfusion was ensured for 30 min following priapism. Rats in Group 4 rats were given oxytocin 30 min before the induction of reperfusion following priapism. All rats were penectomized, and adequate amounts of blood sample were drawn. Inflammation, vasocongestion, desquamation, and edema in penile tissue were scored between 0 and 3 points (0: normal, 1: mild, 2: moderate, 3: severe) to evaluate the severity of tissue damage. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and the levels of malondialdehyde (MDA), and nitric oxide (NO) in blood samples were determined spectrophotometrically.

RESULTS

In histopathological examination, statistically significant positive changes were detected in vasocongestion, inflammation, desquamation, and edema scores in Group 4 than in Group 2 and Group 3 (p < 0.001). Biochemical test results revealed that NO levels were significantly lower in Group 4 than in Group 3 (p < 0.001). Serum GSH-Px activities in Group 4 significantly increased when compared with the other groups 2 and 3 (p = 0.002, p = 0.001, respectively). There was no statistical difference among the groups regarding SOD activities and MDA levels (p > 0.05).

CONCLUSIONS

Oxytocin protected against priapism-induced ischemia-reperfusion injury developed in cavernosal tissue as observed based on histopathological and biochemical evidence. Although this is an experimental study, oxytocin can be thought as an alternative drug in the treatment of priapism.

Non-ischemic priapism following recurrent idiopathic ischemic priapism treated successfully with selective arterial embolization and postoperative vacuum therapy before delayed inflatable penile prosthesis placement: A single case report

Introduction

Priapism is defined as a persistent tumescence or erection of the penis not associated to sexual desire and/or stimulation. Idiopathic recurrent priapism may also occasionally follow treatment of veno‐occlusive priapism and represents a diagnostic and therapeutic challenge.

Case presentation

We report a single case of non‐ischemic priapism that resulted after distal shunting procedure for severe and prolonged ischemic priapism and yet occurred without evidence of a cavernosal–sinusoidal fistula that was successfully treated with a bilateral selective arterial embolization. Our protocol of delayed inflatable penile prosthesis placement after a vacuum erectile device program was implemented.

Conclusions

The continuing use of a vacuum erectile device represented a bridge and an adjuvant therapy useful to facilitate later prosthesis placement. Anatomical and functional outcomes were optimal. No postoperative complaints or complications were reported.

The possible protective effects of dipyridamole on ischemic reperfusion injury of priapism

PURPOSE

To investigate the protective effects against ischemia reperfusion injury of dipyridamole in a model of induced priapism in rats.

MATERIALS AND METHODS

Twenty-four male Sprague-Dawley rats were divided into four groups, control, P/R, P/R+DMSO and P/R+D. 3ml blood specimens were collected from vena cava inferior in order to determine serum MDA, IMA, TAS, TOS and OSI values, and penile tissue was taken for histopathological examination in control group. Priapism was induced in P/R group. After 1h, priapism was concluded and 30 min reperfusion was performed. In P/R+DMSO group 1ml/kg DMSO was administered intraperitoneally 30 min before reperfusion, while in P/R+D group 10mg/kg dipyridamole was administered intraperitoneally 30 min before reperfusion. Blood and penis specimens were collected after the end of 30 min reperfusion period. Sinusoidal area (μm2), tears in tunica albuginea and injury parameters in sinusoidal endothelium of penis were investigated.

RESULTS

Histopathological examination revealed no significant changes in term of sinusoidal area. A decrease in tears was observed in P/R+D group compared to P/R group (p<0.05). Endothelial injury decreased in P/R+D group compared to P/R group (p>0.05). There were no significant differences in MDA and IMA values between groups. A significant increase in TOS and OSI values was observed in P/R+D group compared to P/R group. A significant decrease in TAS levels was observed in P/R+D group compared to the P/R group.

CONCLUSIONS

The administration of dipyridamole before reperfusion in ischemic priapism model has a potential protective effect against histopathological injury of the penis.

The Case Report of Priapus and a Modern Approach to an Ancient Affliction

INTRODUCTION

Priapism, taking its name from God Priapus, is total or partial erection lasting longer than 4 hours independent of sexual stimulus and can result in erectile dysfunction. There are three subtypes of priapism.

AIM

To review the three subtypes of priapism, their pathophysiology, current treatment options, and complications.

METHODS

The literature including priapism guidelines, review articles, and current trial studies was reviewed and the priapism type of God Priapus was investigated according to the mythology.

MAIN OUTCOME MEASURES

All three types of priapism were reviewed for etiology, diagnosis, and management. Medical and surgical treatment options were reviewed in relation to the current literature. Special emphasis concerned current treatment strategies and controversial surgical topics.

RESULTS

Ischemic priapism is the most common type, constituting 95% of all cases, and is an emergency. First-line treatments are blood aspiration and intracavernosal sympathomimetic drug injections. If these fail, then surgical shunt operations are recommended. A T-shunt combined with corporal tunneling is the currently popular option. Immediate penile prosthesis implantation is recommended for patients who present 48 to 72 hours after the onset of a priapism episode. High-flow priapism is caused by irregular arterial cavernosal blood flow, which usually occurs after a blunt perineal trauma. Antiandrogens and selective arterial embolization are the treatment options. Stuttering priapism is repetitive, self-limiting ischemic priapism and frequent in patients with sickle cell anemia. Ketoconazole is safe, cheap, and effective and appears to be a logical and suitable current treatment option to prevent further episodes, which is the primary treatment goal of stuttering priapism.

CONCLUSION

Priapism is a relatively common condition but not well known by clinicians. The lack and delay of treatment result in irreversible complications such as erectile dysfunction. Each type of priapism should be diagnosed and treated correctly with caution.

Nitrergic Mechanisms for Management of Recurrent Priapism

INTRODUCTION

Priapism is a condition involving prolonged penile erection unrelated to sexual interest or desire. The ischemic type, including its recurrent variant, is often associated with both physical and psychological complications. As such, management is of critical importance. Ideal therapies for recurrent priapism should address its underlying pathophysiology.

AIM

To review the available literature on priapism management approaches particularly related to nitrergic mechanisms.

METHODS

A literature review of the pathophysiology and management of priapism was performed using PubMed.

MAIN OUTCOME MEASURE

Publications pertaining to mechanisms of the molecular pathophysiology of priapism.

RESULTS

Nitrergic mechanisms are characterized as major players in the molecular pathophysiology of priapism. PDE5 inhibitors represent an available therapeutic option with demonstrated ability in attenuating these underlying nitrergic derangements. Several additional signaling pathways have been found to play a role in the molecular pathophysiology of priapism and have also been associated with these nitrergic mechanisms.

CONCLUSION

An increasing understanding of the molecular pathophysiology of priapism has led to the discovery of new potential targets. Several mechanism-based therapeutic approaches may become available in the future.

Erectile dysfunction after sickle cell disease-associated recurrent ischemic priapism: profile and risk factors

INTRODUCTION

Risk factors associated with erectile dysfunction (ED) that results from recurrent ischemic priapism (RIP) in sickle cell disease (SCD) are incompletely defined.

AIM

This study aims to determine and compare ED risk factors associated with SCD and non-SCD-related "minor" RIP, defined as having ≥2 episodes of ischemic priapism within the past 6 months, with the majority (>75%) of episodes lasting <5 hours.

METHODS

We performed a retrospective study of RIP in SCD and non-SCD patients presenting from June 2004 to March 2014 using the International Index of Erectile Function (IIEF), IIEF-5, and priapism-specific questionnaires.

MAIN OUTCOME MEASURES

Prevalence rates and risk factor correlations for ED associated with RIP.

RESULTS

The study was comprised of 59 patients (40 SCD [mean age 28.2 ± 8.9 years] and 19 non-SCD [15 idiopathic and four drug-related etiologies] [mean age 32.6 ± 11.7 years]). Nineteen of 40 (47.5%) SCD patients vs. four of 19 (21.1%) non-SCD patients (39% overall) had ED (IIEF <26 or IIEF-5 <22) (P = 0.052). SCD patients had a longer mean time-length with RIP than non-SCD patients (P = 0.004). Thirty of 40 (75%) SCD patients vs. 10 of 19 (52.6%) non-SCD patients (P = 0.14) had "very minor" RIP (episodes regularly lasting ≤2 hours). Twenty-eight of 40 (70%) SCD patients vs. 14 of 19 (73.7%) non-SCD patients had weekly or more frequent episodes (P = 1). Of all patients with very minor RIP, ED was found among 14 of 30 (46.7%) SCD patients vs. none of 10 (0%) non-SCD patients (P = 0.008). Using logistic regression analysis, the odds ratio for developing ED was 4.7 for SCD patients, when controlling for RIP variables (95% confidence interval: 1.1-21.0).

CONCLUSIONS

ED is associated with RIP, occurring in nearly 40% of affected individuals overall. SCD patients are more likely to experience ED in the setting of "very minor" RIP episodes and are five times more likely to develop ED compared with non-SCD patients.

Sustained nitric oxide (NO)-releasing compound reverses dysregulated NO signal transduction in priapism

We evaluated the therapeutic potential of a sustained nitric oxide (NO)-releasing compound to correct the molecular hallmarks and pathophysiology of priapism, an important but poorly characterized erectile disorder. 1,5-Bis-(dihexyl-N-nitrosoamino)-2,4-dinitrobenzene (C6') and an inactive form of the compound [1,5-bis-(dihexylamino)-2,4-dinitrobenzene (C6)] were tested in neuronal cell cultures and penile lysates for NO release (Griess assay) and biological activity (cGMP production). The effect of local depot C6' or C6 was evaluated in mice with a priapic phenotype due to double neuronal and endothelial NO synthase deletion (dNOS(-/-)) or human sickle hemoglobin transgenic expression (Sickle). Changes in NO signaling molecules and reactive oxygen species (ROS) surrogates were assessed by Western blot. The physiological response after C6' treatment was assessed using an established model of electrically stimulated penile erection. C6' generated NO, increased cGMP, and dose dependently increased NO metabolites. C6' treatment reversed abnormalities in key penile erection signaling molecules, including phosphodiesterase type 5, phosphorylated endothelial nitric oxide synthase, and phosphorylated vasodilator-stimulated phosphoprotein. In Sickle mice, C6' also attenuated the increased ROS markers gp91(phox), 4-hydroxynonenal, and 3-nitrotyrosine. Finally, C6' corrected the excessive priapic erection response of dNOS(-/-) mice. Exogenous sustained NO release from C6' corrects pathological erectile signaling in mouse models of priapism and suggests novel approaches to human therapy.

Sildenafil citrate-restored eNOS and PDE5 regulation in sickle cell mouse penis prevents priapism via control of oxidative/nitrosative stress

Sildenafil citrate revolutionized the practice of sexual medicine upon its federal regulatory agency approval approximately 15 years ago as the prototypical phosphodiesterase type 5 inhibitor indicated for the treatment of male erectile dysfunction. We now provide scientific support for its alternative use in the management of priapism, a clinical disorder of prolonged and uncontrolled penile erection. Sildenafil administered continuously to sickle cell mice, which show a priapism phenotype, reverses oxidative/nitrosative stress effects in the penis, mainly via reversion of uncoupled endothelial nitric oxide synthase to the functional coupled state of the enzyme, which in turn corrects aberrant signaling and function of the nitric oxide/cyclic GMP/protein kinase G/phosphodiesterase type 5 cascade. Priapism tendencies in these mice are reverted partially toward normal neurostimulated erection frequencies and durations after sildenafil treatment in association with normalized cyclic GMP concentration, protein kinase G activity and phosphodiesterase type 5 activity in the penis. Thus, sildenafil exerts pleiotropic effects in the penis that extend to diverse erection disorders.

Does pentoxifylline enhance the recovery of erectile function after a T-shunt procedure for prolonged ischaemic priapism? A prospective randomised controlled trial

Objective

To evaluate the role of oral pentoxifylline for enhancing the recovery of erectile function (EF) in patients who had a T-shunt, a technically simple procedure for treating prolonged ischaemic priapism, as the recovery of EF has been reported in many patients treated by this procedure.

Patients and methods

This prospective randomised study was conducted on 40 patients with prolonged ischaemic priapism treated with a T-shunt. Patients were randomly divided into two groups; group A received oral pentoxifylline from the second day after surgery for 3 months, and group B received placebo. Patients were followed for 18 months.

Results

The pain resolved in all patients, and EF recovered in 15 patients in group A and 10 in group B within 3 months. All patients but three had recovery of EF within the 18-month follow-up. Six patients had recovery of EF by using on-demand 50 mg sildenafil. The three patients who did not recover EF had a penile prosthesis implanted after the end of the study.

Conclusion

Pentoxifylline had no significant effect on the recovery of EF after a T-shunt procedure, but a larger study (double-blinded) is required for a more accurate assessment of any beneficial effect of pentoxifylline after a T-shunt procedure.

Sickling cells, cyclic nucleotides, and protein kinases: the pathophysiology of urogenital disorders in sickle cell anemia

Sickle cell anemia is one of the best studied inherited diseases, and despite being caused by a single point mutation in the HBB gene, multiple pleiotropic effects of the abnormal hemoglobin S production range from vaso-occlusive crisis, stroke, and pulmonary hypertension to osteonecrosis and leg ulcers. Urogenital function is not spared, and although priapism is most frequently remembered, other related clinical manifestations have been described, such as nocturia, enuresis, increased frequence of lower urinary tract infections, urinary incontinence, hypogonadism, and testicular infarction. Studies on sickle cell vaso-occlusion and priapism using both in vitro and in vivo models have shed light on the pathogenesis of some of these events. The authors review what is known about the deleterious effects of sickling on the genitourinary tract and how the role of cyclic nucleotides signaling and protein kinases may help understand the pathophysiology underlying these manifestations and develop novel therapies in the setting of urogenital disorders in sickle cell disease.

In vitro and in vivo animal models in priapism research

INTRODUCTION

Priapism is an enigmatic yet devastating clinical phenomenon. In the last two decades, the use of various animal models to study this disorder has dramatically advanced our understanding of this mysterious disorder.

AIM

This report reviews various animal models used to study ischemic priapism and informs basic science researchers the broad view of priapism research.

METHODS

Retrospective review of pertinent literature from the last two decades via PubMed search using the keywords "ischemic priapism" and "priapism model."

MAIN OUTCOME MEASURES

  Findings on the animal models used in ischemic priapism research and its advantages and limitations.

RESULTS

In vitro and in vivo animal models varying from dogs, cats, rabbits, rats to mice were used in priapism research. In vitro models included: (i) corpora cavernosa smooth muscle (CCSM) strip in organ bath; (ii) corporal tissue binding assay; (iii) CCSM cell culture under hypoxia/anoxia. In vivo models could be categorized as: (i) pharmacologically induced by corpus cavernosum medicine injection; (ii) ventilation induced by tidal volume control; (iii) mechanical induced by a constrictor band placed around the base of the penis combined with induced erection; (iv) genetic engineered by intracorporal gene transfer, transgenic, or gene knock-out.

CONCLUSIONS

The ischemic priapism animal models are shifting from pharmaceutically or mechanically induced to genetically engineered. The knowledge generated by those models is enhancing our understanding and management of this clinical challenge.

Establishment of a transgenic sickle-cell mouse model to study the pathophysiology of priapism

INTRODUCTION

Priapism is a poorly understood disease process with little information on the etiology and pathophysiology of this erectile disorder. One group of patients with a high prevalence of priapism is men with sickle-cell disease.

AIM

Establish an in vivo transgenic sickle-cell mouse model to study the pathophysiology of sickle-cell disease-associated priapism.

METHODS

Transgenic sickle-cell disease mice, expressing human sickle hemoglobin, were utilized. Three groups of mice were used: (i) wild type (WT), (ii) sickle-cell heterozygotes (Hemi), and (ii) sickle-cell homozygotes (Sickle). Two age groups of each cohort of mice were utilized: young adult (4-6 months) and aged (18-22 months).

MAIN OUTCOME MEASURES

Histological (trichrome stain to measure ratio of collagen to smooth muscle), penile hydroxyproline content (collagen content), and transmission electron microscopic analysis of WT, Hemi, and Sickle mice penes, as well as in vivo erectile responses [change in intracavernous pressure (ICP)] to cavernous nerve stimulation (CNS), were determined. The frequency of erectile responses (erections/hour) pre- and poststimulation was also measured in each of the experimental groups.

RESULTS

Sickle mice had increased (P < 0.05) collagen to smooth muscle ratio and hydroxyproline content in the penis when compared with WT and Hemi mice penes. Transmission electron microscopy demonstrated thickened smooth muscle cell bundles, disruption of the endothelial lining of the corporal sinusoids, and increased (P < 0.05) caveolae number. Sickle mice had significantly (P < 0.05) higher ICP to CNS and increased (P < 0.05) frequency of erections pre- and post-CNS when compared with WT and Hemi mice erectile responses. Sickle mice did develop ED (change in ICP in response to CNS) with increasing age.

CONCLUSION

The morphometric changes of the penis and exaggerated in vivo erectile responses support the use of this transgenic sickle-cell disease animal model to study the pathophysiological mechanisms involved in sickle-cell disease-associated priapism.

Increased cavernosal relaxations in sickle cell mice priapism are associated with alterations in the NO-cGMP signaling pathway

INTRODUCTION

Priapism is defined as prolonged and persistent penile erection, unassociated with sexual interest or stimulation, and is one of the many serious complications associated with sickle cell disease (SCD).

AIM

The aim of this study was to evaluate the role of the NO-cGMP signaling pathway in priapism in Berkeley murine model of SCD (SS).

METHODS

SS mice and C57BL/6 mice (control) penile tissues were removed and the erectile tissue within the corpus cavernosum (CC) was surgically dissected free. The strips were mounted in 10 mL organ baths containing Krebs solution at 37 degrees C (95% O(2), 5% CO(2), pH 7.4), and vertically suspended between two metal hooks.

MAIN OUTCOME MEASURES

Cumulative concentration-response curves were constructed for acetylcholine (ACh; endothelium-dependent responses), sodium nitroprusside (SNP; endothelium-independent relaxations) and BAY 41-2272 (a potent activator of NO-independent site of soluble guanylate cyclase) in CC precontracted with phenylephrine. Cavernosal responses induced by frequency-dependent electrical field stimulation (EFS) were also carried out to evaluate the nitrergic cavernosal relaxations.

RESULTS

In SS mice, ACh-induced cavernosal relaxations were leftward shifted by 2.6-fold (P < 0.01) that was accompanied by increases in the maximal responses (78 +/- 5% and 60 +/- 3% in SS and C57B6/6J mice, respectively). Similarly, SNP- and BAY 41-2272-induced CC relaxations were leftward shifted by approximately 3.3- and 2.2-fold (P < 0.01) in SS mice, respectively. A significant increase in maximal responses to SNP and BAY 41-2272 in SS mice was also observed (113 +/- 6% and 124 +/- 5%, respectively) compared with C57B6/6J mice (83 +/- 4% and 99 +/- 2%, respectively). The EFS-induced cavernosal relaxations were also significantly higher SS mice.

CONCLUSION

These results showed that SS mice exhibit amplified corpus carvenosum relaxation response mediated by NO-cGMP signaling pathway. Intervention in this signaling pathway may be a potential therapeutic target to treat SCD priapism.

Clinical course linkage among different priapism subtypes: Dilemma in the management strategies

OBJECTIVES

Priapism is a rare condition whose management differs according to the etiology. We report the clinical course of three forms of priapism to assess the feasibility and safety of recent management strategies.

METHODS

The study included eight patients complaining of persistent erection for >/=4 h who were treated in our institution between January 1996 and July 2007.

RESULTS

Overall, we categorized 12 cases of priapism in eight patients divided as follows: five cases of ischemic priapism (IP), three of stuttering priapism (SP), and four of non-ischemic priapism (NIP). Two of five IP patients needed a shunt procedure, which led to the subsequent erectile dysfunction. The other three were treated successfully with a corporal injection of sympathomimetic agents and subsequently suffered from SP. One of the three SP patients suffered from mimicked NIP with increased arterial blood flow during the initial treatment for IP. Four of the NIP patients including the mimicked one achieved complete detumescence, through arterial embolization in two and conservative management in two.

CONCLUSIONS

Current management seems effective and safe in the short-term. However, the long-term outcome of the treatment for IP is still disappointing. Careful long-term observation is needed for an appropriate management.

Priapism: New concepts in the pathophysiology and new treatment strategies

Priapism is defined as prolonged and persistent erection of the penis without sexual stimulation. This is a poorly understood disease process, and we have little information on the etiology and pathophysiology of this erectile disorder. Two main types of priapism exist: low-flow (ischemic) and high-flow (nonischemic) priapism. When the physician first diagnoses which type of priapism exists, distinguishing the type of priapic event is paramount in order to choose the correct treatment options. Until recently, we had not sufficiently understood the pathogenesis of this erectile disorder and therefore, could not effectively manage its pathologic consequences of erectile tissue damage and erectile dysfunction. In this review, the proposed pathogenesis of ischemic priapism is reviewed, and a survey regarding novel treatment modalities is given.

Nitric oxide/redox-based signalling as a therapeutic target for penile disorders

Oxidative and/or nitrosative stress is implicated in the pathogeneses of assorted penile disorders of clinical significance, notably erectile dysfunction, priapism and penile fibrosis. It is becoming increasingly recognised that the generation and activity of reactive oxygen and nitrogen species in the penis influence vascular homeostasis of this organ, with adverse effects exerted at cellular and molecular levels. Furthermore, these elements may interact with molecular signalling pathways operating in the penis, modulating their functional roles. This interaction in particular suggests that by accessing molecular targets associated with oxidative/nitrosative stress in the penis, new pharmacotherapeutic approaches may be developed to promote normal erectile ability and preserve erectile tissue health. This notion pertains to, but also extends beyond, interventions which predictably target components of the nitric oxide-based signal transduction pathway for the on-demand treatment of erectile dysfunction. The next line of pharmaceuticals for disorders of the penis, in general, may well spawn from an integrative understanding of the complex regulatory interactions influenced by, as well as influencing nitric oxide signalling in this organ.

Priapismo

Priapism has been defined by AFUD as a pathological condition which consists in a penile erection that persists moreover or is not related to sexual stimulation. Priapism pathophysiology has remained unknown until differents groups of clinical investigators began to research about this entity in patients complaining of erectile dysfunction, who where receiving treatment with intracavernosal vasoactive molecules. Priapism can be clasified into ischaemic (venocclusive): the most prevalent type, or Arterial (non-ischaemic). The purpose of this revision is to update the pathophysiology of the two types of priapism and to create an algorithm of therapeutical and diagnostic approach.

TGF-beta1 neutralizing antibodies decrease the fibrotic effects of ischemic priapism

The objective of this study was to evaluate the possible role of transforming growth factor beta 1 (TGF-beta1) antibodies (ab) for the prevention of fibrotic effects of priapism in a rat model. In total, 30 adult Sprague-Dawley rats were divided into five groups. Priapism with 6 h (group 1), priapism with 6 h+ab (group 2), priapism with 24 h (group 3), priapism with 24 h+ab (group 4) and control (group 5). Priapism was induced with a vacuum erection device and a rubber band was placed at the base of the erect penis. At 1 h after the initiation of priapism, TGF-beta1 antibodies were given intracavernosaly. All rats underwent electrical stimulation of the cavernous nerve after 8 weeks. Intracavernous and systemic blood pressures were measured during the procedure. Rats in group 1 showed significantly higher (intracavernosal pressure (ICP) pressures to cavernous nerve stimulation and had higher ICP/BP ratios when compared to other groups. Similarly, histopathologic examination revealed less fibrosis in group 2, compared with the other groups. Consequently, TGF-beta1 antibodies antagonise the fibrotic effects of TGF-beta1, especially in cases with duration of priapism less than 6 h.

Comparison of oxidative/antioxidative status of penile corpus cavernosum blood and peripheral venous blood

The aim of the study is to determine and to compare the oxidative and antioxidative status of penile corpus cavernosum and peripheral venous blood. A total of 28 adult healthy males were included in the study. Whole blood was simultaneously withdrawn from penile corpus cavernosum and the cubital vein and their plasma separated. Total antioxidant capacity (TAC), vitamin C, total protein, albumin, uric acid, bilirubin and total peroxide (TP) levels of both plasma samples were measured and compared. While TAC, total protein, albumin, bilirubin and uric acid levels were higher, vitamin C levels were lower in cavernosal blood than that of peripheral blood. On the other hand, TP level was found to be higher in penile blood samples than that of peripheral blood. We thought that the normal erectile process of the penile cavernosal body leads to increased production of oxidants as in the mechanism of ischaemia-reperfusion; however, the increase of TAC can prevent development of oxidative injury.