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Simultaneous hermaphroditism is, at least initially, favoured by selection under low density — and therefore it can be assumed that sperm competition has little importance in this sexual system. However, many simultaneously hermaphroditic nudibranchs have both an allo-sperm storage organ (the seminal receptacle) and an allo-sperm digesting organ (the copulatory bursa), suggesting the possibility of the occurrence of sperm competition. A nudibranch, Chromodoris reticulata, autotomizes its penis after every copulation and replenishes it within about 24 h to perform another copulation. We observed that the surface of the autotomized penis was covered with many backward-pointing spines and that a sperm mass was often entangled on the spines. This suggests that the nudibranch removes sperm that is already stored in a mating partner's sperm storage organ(s) with its thorny penis. Using six microsatellite markers, we determined that the sperm mass attached to the penis were allo-sperm originating from individual(s) that had participated in prior copulations. We revealed that C. reticulata performed sperm removal using the thorny penis. These results suggest that competition in fertilization is quite intense and mating frequency in the wild is relatively high in this species. [ABSTRACT FROM AUTHOR]

Penile plethysmography (PPG) is a measure of sexual interests that relies heavily on the stimuli it uses to generate valid results. Ethical considerations surrounding the use of real images in PPG have further limited the content admissible for these stimuli. To palliate this limitation, the current study aimed to combine audio and visual stimuli by incorporating computer-generated characters to create new stimuli capable of accurately classifying sex offenders with child victims, while also increasing the number of valid profiles. Three modalities (audio, visual, and audiovisual) were compared using two groups (15 sex offenders with child victims and 15 non-offenders). Both the new visual and audiovisual stimuli resulted in a 13% increase in the number of valid profiles at 2.5 mm, when compared to the standard audio stimuli. Furthermore, the new audiovisual stimuli generated a 34% increase in penile responses. All three modalities were able to discriminate between the two groups by their responses to the adult and child stimuli. Lastly, sexual interest indices for all three modalities could accurately classify participants in their appropriate groups, as demonstrated by ROC curve analysis (i.e., audio AUC = .81, 95% CI [.60, 1.00]; visual AUC = .84, 95% CI [.66, 1.00], and audiovisual AUC = .83, 95% CI [.63, 1.00]). Results suggest that computer-generated characters allow accurate discrimination of sex offenders with child victims and can be added to already validated stimuli to increase the number of valid profiles. The implications of audiovisual stimuli using computer-generated characters and their possible use in PPG evaluations are also discussed. [ABSTRACT FROM AUTHOR]

The current study examined the extent to which 1136 men were able to inhibit their sexual arousal on a phallometric assessment, when instructed to do so. Although the observed changes between the two conditions (i.e., Normal and Suppression) were small to moderate in magnitude, the change was not more than what would be expected by measurement error for most participants (e.g., 83% of pedophilic sex offenders against children did not successfully inhibit their sexual arousal in the Suppression condition). There were very few variables that were associated with the ability to suppress. Higher Pedophilia Index scores in the Suppression condition predicted a greater likelihood of sexual recidivism among sex offenders (hazard ratio = 1.17, 95% CI [1.04, 1.32]), but the ability to suppress sexual arousal was not found to predict sexual recidivism. The current study highlights the importance of accounting for measurement error and found that, when doing so, most sex offenders against children are unable to successfully inhibit their sexual arousal to children when instructed to do so, and that the ability to suppress sexual arousal is not associated with recidivism. [ABSTRACT FROM AUTHOR]

Sexual offending is a significant public health problem in the USA due to its prevalence and the substantial impact it has on victims, victims' families, and the legal and mental health systems. The assessment of sexual offender recidivism risk is an important aspect of developing effective management strategies for sexual offenders in terms of placement, treatment, and other interventions. Researchers have developed numerous tools to aid in the assessment of sexual violence recidivism risk, including actuarial measures, structured professional judgment methods, and psychophysiologic assessment of sexual interests. The Static-99R and Sexual Violence Risk-20 are two instruments that have received substantial research attention for their ability to accurately compare offenders' risk of recidivism to normative group data. Penile plethysmography and visual reaction time are used to evaluate subjects' responses to sexual stimuli in an effort to characterize offenders' sexual arousal and interest, respectively. Though current research has focused on risk assessment tools' predictive utility, future research will need to examine the impact that actuarial and structured professional judgment tools have on reducing recidivism if they are to have relevance in the management of sexual offenders. [ABSTRACT FROM AUTHOR]

Purpose: High-flow priapism is often a sequela of perineal trauma resulting in an arteriocavernosal fistula (ACF) between a cavernosal artery and lacunar spaces of the penis. We report our experience utilizing magnetic resonance angiography (MRA) in addition to color Doppler Sonography (CDS) in the workup and treatment planning of 4 patients with high-flow priapism. Methods: All patients had suspected high-flow priapism diagnosed by clinical exam and CDS and underwent MRA of the penis prior to sub-selective arterial embolization (SSAE) of the feeding vessel(s). Results: While CDS is valuable in diagnosing and lateralizing high-flow priapism, it does not provide clear anatomic delineation of the number and origin of feeding vessels. MRA provided demonstration of the fistula, demonstrated bilateral ACF supply in 2 patients, and afforded three-dimensional display of the feeding vessels which facilitated pre-embolization planning. Conclusions: In all four cases, MRA was an effective tool for displaying arterial and venous anatomy, localizing the ACF, and planning subsequent SSAE. MRA influenced management in two out of 4 patients by demonstrating bilateral feeding vessels to their ACFs that required bilateral SSAE. [ABSTRACT FROM AUTHOR]

The aim of the study is to evaluate the incidence and the echographic characteristics of minimal lesions of cavernosum corpora and tunica albuginea (TA) in subjects reporting erectile dysfunction (ED), which could suggest the suspicious of La Peyronie's disease (LPD). In total, 185 patients (pts) underwent dynamic penile Ultrasound Color Doppler (USCD) for ED. None of the pts presented any clinical symptoms or any clinical findings for LPD. In this study we evaluated, using USCD, thickness, echogenicity, regularity of the surface profile of the dorsal TA, the intercavernous and the intercaverno-spongeous septa, and the extension of the eventual pathologic lesions. In all, 16 pts (8.7%) presented minimal lesions at the ultrasound examinations. In nine of these pts (56%) the lesion was localized at the dorsal position, in six (38%) on the intercavernous septum and in one patient (6%) in both positions. The dorsal lesions were represented in nodular form in four pts (4%), and in diffuse form in five pts (55%). The nodular form was present in all the intercavernous septal lesions observed. As reported in the literature, USCD represents the investigative technique of choice in the study of LPD and in ED. Furthermore, the results of this study suggest that this technique could allow the localization of minimal lesions attributable to LPD during a preclinical phase of this disease. The localization of these lesions could permit to start a therapeutic approach during an early phase of the disease.International Journal of Impotence Research (2006) 18, 517–521. doi:10.1038/sj.ijir.3901459; published online 9 March 2006 [ABSTRACT FROM AUTHOR]

This study compared the mean levels of sexual response to children produced by four groups of men with sexual offences against prepubescent girls and two comparison groups with other offences or no offences. All groups (N = 291) consisted of patients referred for clinical assessment of their sexual behavior or interests. Group assignment was determined by the victim's age and her relation to the patient: biological daughter; stepdaughter; other biologically related girl (e.g., sister, niece, granddaughter); unrelated girl; adult woman; and no known victim. The men with sexual offences had precisely one known victim each. The patients with offences may or may not have denied the act of which they were accused, but all patients denied an erotic preference for children. Sexual response to children was assessed by means of phallometric testing, a psychophysiological technique in which the individual's penile blood volume is monitored while he is presented with a standardized set of laboratory stimuli depicting male and female children and adults. The results indicated that the mean level of pedophilic response in men with offences against daughters or stepdaughters is intermediate between that in men with offences against otherwise-related or unrelated girls and that in men with no offences against girls at all. [ABSTRACT FROM AUTHOR]

Discusses the general use of animal models for investigation of the physiology of erection. Understanding of penile erection under neurophysiological control; Exploration of the central nervous system control of penile erection; Testing therapeutic strategies for erectile dysfunction.

Identifies clinical and engineering parameters of the flaccid penis for prediction of penile size during erection in patients who have erectile dysfunction. Measurement of the forces required to stretch the penis; Use of a specially designed gauge; Calculation of the regression relationships of the measured dimensions; Employment of the values of the relative and absolute elongations of stretched penis.

Presents a theory to further the understanding of the physiology of corporal veno-occlusion. Possible contribution to corporal venous outflow resistance due to venule stretching with resultant luminal narrowing when penile volume increases during erection; Indication that stretch-associated venule resistance may be due to decreased sub-tunical venule diameter and increased sub-tunical venule length.

The purpose of this study was to evaluate the penile vascular function by color Doppler ultrasonography (CDU) in patients with Peyronie's disease. A total of 136 men with Peyronie's disease were stratified according to their potency by history as Group I consisting of potent patients and Group II consisting of patients with erectile dysfunction. They were all evaluated by penile CDU. Overall, 70.6% had erectile dysfunction by history. CDU revealed penile vascular abnormalities in 76.5%. In Group I, veno-occlusive dysfunction (VOD) was observed in 40% while mixed (arterial + venous) vascular disease was diagnosed in 10%. Penile vascular disease was detected in 87.5% patients in Group II (ie VOD in 28%, arterial disease in 9.3% and mixed vascular disease in 50%). The prevalence of arterial disease on CDU among Peyronie' patients with erectile dysfunction (59.3%) was significantly (P < 0.05) higher then it was among potent patients (10%). The prevalence of pure VOD was almost similar for patients with or without erectile dysfunction (P < 0.05). We conclude that penile vascular abnormalities can be observed in 76.5% on cases with Peyronie's disease by CDU and this ratio significantly increases to 87.5% among cases with erectile dysfunction by history. Our data also indicate that arterial disease, accounts for much of the diminished rigidity in men with Peyronie's disease. [ABSTRACT FROM AUTHOR]

Studies changes in penile tunica albuginea (TA) associated with aging and diabetes mellitus. Role of TA in the mechanism of erection; Increase in thickness and loss of undulation of collagen bundles of penile TA; Causes of the compromised rigidity of the penis during erection under both conditions.

Sympathetic skin responses (SSR) are a simple procedure to investigate sympathetic activity. More specifically, SSR elicited from median nerve stimulation and recorded from the feet and genitals assess sympathetic activity resulting from thoracic-lumbar (TL) innervation. Since TL innervation is also involved in the mediation of psychogenic erection in spinal cord injured men, this study investigated the relationship between SSR and psychogenic erection in spinal cord injured subjects. The results support a general association between SSR and psychogenic erection and show that subjects who maintain SSR responses in the feet and genitals generally maintain psychogenic erections as well. Inconsistent cases are discussed from a theoretical and clinical perspective and overall results are discussed in terms of their clinical application in the evaluation of sexual function in spinal cord injured men. [ABSTRACT FROM AUTHOR]

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 24-62y) 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 is proposed. [ABSTRACT FROM AUTHOR]

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 ± 0.25kg (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. [ABSTRACT FROM AUTHOR]

Improvement in natural erections has been reported in approximately 9% of impotent men using intracavernous injections of vasoactive drugs for erection induction. The mechanisms which may account for this improvement are psychogenic, improved cavernous hemodynamics, prostaglandin-induced angiogenesis, improved cavernous oxygenation, cavernous smooth muscle hypertrophy and/or normal episodic fluctuations in erectile function. A review of the basic science literature on this subject reveals several theoretical explanations for this phenomenon but a review of the clinical literature reveals little convincing evidence that physiologic and/or pharmacologic factors are responsible for improvement in natural erections with intracavernous injection therapy. Furthermore, the prevalence of a placebo effect from impotence therapy exceeds the reported rate of improvement in natural or spontaneous erections. The most plausible explanations for spontaneous improvement in erections during or after intracavernous injection therapy are psychogenic and episodic variations in erectile function, rather than physiologic or pharmacologic factors. However, intracavernous injection therapy started soon after radical prostatectomy may have a protective effect in preserving normal cavernous physiology and erectile function in men being treated for prostate cancer. [ABSTRACT FROM AUTHOR]

A comparative study in 103 unselected patients with erectile dysfunction between MUSE™ up to 1000 µg and intracavernous Alprostadil (Prostavasin™) up to 20 µg provided total response-rates of 43% (MUSE™) vs 70% (Prostavasin™). Complete rigid erections were reached in 10% (MUSE™) VS 48% (Prostavasin™). The average end-diastolic flow values in the deep penile arteries ranged between 9.2-9.4 cm/s after MUSE™ and 4.5-4.8 cm/s after i.c. Alprostadil confirming the investigator's assessment, that in the vast majority of patients MUSE™ were not able to induce a complete cavernous smooth muscle relaxation. In terms of side effects the reported penile pain/burning-rate after MUSE™ was 31.4% compared to 10.6% after i.c. Alprostadil. In addition after MUSE™ clinically relevant systemic side-effects like dizziness, sweating and hypotension occurred in 5.8% with syncope in 1%. No circulatory side-effects were encountered after i.c. Alprostadil. Urethral bleeding after MUSE™-application was observed in 4.8%. Due to the superior efficacy and lower side-effects self-injection therapy with Alprostadil remains the 'Gold Standard' in the management of male impotence. MUSE™ should be reserved for a subset of patients suffering from erectile dysfunction. [ABSTRACT FROM AUTHOR]

Focuses on the history, methodology and the modes of measurement on the use of radioactive tracers in the evaluation of penile hemodynamics. Association with the categories of investigative methods in erectile dysfunction; Labeled blood-pool, tracer washout, tracer washing and combined blood-pool/tracer and tracer washout examinations; Effectiveness of methods and in the analysis of penile hemodynamics.

Discusses some principles of integrated and balance control vasodilation and vasoconstriction in the penis. Phylogeny and the inevitability of multiple and overlapping systems; Role of growth induction and regression; Importance of time in the study of penile structure and function.

Focuses on the radiologic evaluation of penile arterial anatomy in arteriogenic impotence using duplex ultrasonography. Effect of penile arterial variability on sonographic arterial evaluation; Role of magnetic resonance and radionuclide imaging in the evaluation of vasogenic impotence; Appreciation of the type and frequency of anatomic variants and potential collateral routes.

Focuses on the role of signal transduction and cell-to-cell communication in coordinating corporal smooth muscle tone and penile erection. Sufficiency of corporal smooth muscle relaxation to elicit a sustained erection; Lack of knowledge on the mechanical physiology of erection; Outline of a cogent explanation for the rapid and syncytial integration of the effects of diverse stimuli in penile smooth muscle cells.

Human penile erection is a complex phenomenon mediated through the coordinated interaction among the nervous, vascular, and musculosystems. For social and ethical reasons, the mechanism and hemodynamics of this essential human function remained speculative and controversial for many years. In the past decade, however, advances in technology, together with a marked increase in clinical and research activity, have resolved some of the controversy and have provided a better understanding of erectile physiology. In this essay, we will review traditional concepts, as well as the new and exciting findings from many different research centers, concerning the physiologic mechanisms of penile erection that involve the arterial, venous, and nervous systems. [ABSTRACT FROM AUTHOR]

Focuses on functional measurements of penile erection in feline, canine and primate animal models. Investigation of corpus cavernosal smooth muscle physiology and pharmacology for the development of specific medications for sexual dysfunction treatment; Advantages of the animal models.

The article presents details about the anatomy and physiology of the penile erection. The penis, the male genital organ, has a three-cylinder shape, integrated by two vascular tissue bodies, corpora cavernosa and the corpus spongiosurn. Three types of erection are recognized: nocturnal, that follows the rapid eye movement sleep periods; reflexogenic, from genital stimulations; and the central or psychogenic one, with a single or multiple starting point (smell, visual stimulations, recalls etc.). Several neurotransmitters are known to play an active role in erection. The article concludes with the classification of organic-cause erectile dysfunction.