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Biomedical subjects

T F Lue

Publications and source records attributed to T F Lue.

At least 199 records · Page 11Linked to original sources
PubMed1988

The rationale for pharmacologic cavernosography.

To refine the diagnostic method for opacification of aberrant venous drainage in venogenic impotence, an experimental study was done in eight monkeys. In all monkeys, cavernosography after induction of erection by saline perfusion showed significant drainage via the cavernous veins. However, when cavernosography was performed after neurostimulation or papaverine injection, no cavernous drainage was visualized, even when the intracavernous pressure had been significantly lowered by creation of an artificial cavernous leak. Because erection can result from saline perfusion only when the volume perfused exceeds the venous outflow capability, cavernosography during saline-induced erection will always demonstrate the entire venous system and, thus, is of no diagnostic value. Pharmacocavernosography imitates the physiologic venous occlusive mechanism and should therefore be used to identify the abnormally draining veins in venogenic erectile dysfunction.

Animals↗
PubMed1988

Clinical significance of sacral and pudendal nerve anatomy.

The neuroanatomy and neurophysiology of the external urethral closure mechanisms still are under debate because the motor fibers that emanate from the sacral plexus and pudendal nerve to supply this segment have not been traced, nor has their functional interrelationship been established. Therefore, we dissected 3 male human cadavers (aged 31 to 69 years) by tracing the entire sacral plexus, particularly the pudendal nerve, from the cauda equina throughout the branching of the nerves to their final destination. The dissection demonstrated that the extrinsic urethral sphincter, formed by the rhabdosphincter around the membranous urethra as well as the levator ani muscle and pelvic floor (especially the transversus perinei muscle), is innervated by somatic nerve fibers that emanate primarily from sacral roots S2 and S3. In 5 patients with neurogenic lower urinary tract dysfunction electrostimulation of the sacral root and pudendal nerve markedly increased intraurethral closure pressures. Stimulation of the pudendal nerve or its transversus perinei branch alone resulted in an increase in intraurethral closure pressure to 60 to 70 cm. water--an increase similar to that produced by stimulation of the sacral root without neurotomy. By means of neurotomy and/or neural blockade with lidocaine we were able to differentiate between the contributions of each muscular element to the external sphincteric mechanism. Almost 70 per cent of the closure pressure of the external urethral sphincter is induced by stimulation of the S3 ventral root, while the other 30 per cent derives from S2 and S4 neuronal impulses.

Adult↗
PubMed1988

Normal penile anatomy and abnormal penile conditions: evaluation with MR imaging.

The appearance of the normal penis and of a variety of penile abnormalities on magnetic resonance (MR) images was studied in 55 patients with either medium (0.35 T) or high (1.5 T) magnetic field strengths. Penile morphologic characteristics with anatomic detail of the corpora cavernosa and corpus spongiosum were demonstrated in each patient. MR images clearly displayed congenital anomalies (n = 6), penile prostheses (n = 7), fibrous tissue or hematoma due to trauma (n = 8), and fibrous plaque in Peyronie disease (n = 3). MR imaging also demonstrated urethral (n = 6) and penile (n = 5) neoplasms and allowed tumor staging, thus facilitating the surgical approach.

Adolescent↗
PubMed1988

Castration and erection. An animal study.

Castrated dogs (n = 3) need a much higher threshold level of energy to induce erection by electrical stimulation of the cavernous nerve than noncastrated animals (n = 24). In addition the resulting quality of erection, measured as maximal intracavernous pressure (pCC) versus peak systolic blood pressure (BP), was weaker in castrated dogs (pCC = 57% of BP on average) than in noncastrated dogs (pCC = 80% of BP on average). A high venous outflow from the corpora cavernosa in castrated dogs can also explain the shorter duration of erection. This experimental model excludes the interference of subjective factors, such as erotic stimuli and libido on erection, and it seems that androgen deficiency has a direct effect on the neurophysiology of the erectile tissues resulting in a higher tonus of the detumescence factors, which can be explained by an incomplete relaxation of the sinusoidal smooth muscle.

Androgens↗
PubMed1988

Hemodynamics of penile erection.

In the flaccid state, the smooth muscles of the cavernous arterioles and trabeculae are contracted, and minimal blood flow enters the sinusoids. Relaxation of these smooth muscles incites arterial dilation, venous compression, and sinusoidal relaxation and results in penile erection.

Animals↗
PubMed1988

Evaluation of vasculogenic impotence.

Penodynamics, the functional evaluation of erection after intracavernous injection of vasoactive drugs, is a simple screening test that excludes significant vascular problems if full erection occurs within a reasonable period of time. Although it is more invasive than the penile brachial index (PBI), it is well tolerated and easy to perform. There is good evidence that studies on the flaccid penis are less accurate and do not correlate well with the results of functional papaverine testing. To evaluate arteriogenic impotence, sonography and pulsed Doppler analysis combined with papaverine injections provide objective and reproducible measurements of diameter increase and blood flow of each penile artery and have the advantage of being a functional study. Although this equipment is expensive, it is available in many centers where noninvasive vascular flow studies are performed. With training, the technique can be mastered by anyone. The arterial response to papaverine and the resulting erection allow indirect judgment about the venous system. Therefore, the whole penile vasculature can be evaluated with this technique. Currently, many drugs or drug combinations are used to induce artificial erection, not only for diagnosis but also as a therapeutic alternative to penile prostheses. The only physiologic agent is prostaglandin E1, a substance that seems to be as effective as papaverine but can be metabolized within the cavernous tissue and reportedly results in fewer incidences of prolonged erection and priapism. The use of vasoactive drugs is also very helpful for angiographic studies by improving flow and diameter of the penile vessels, which will result in better images of the arterial lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteries↗
PubMed1987

Neuromuscular dysfunction in nonbacterial prostatitis.

Although chronic nonbacterial prostatitis is common, the condition remains poorly understood and refractory to treatment. Another approach, i.e., a urodynamic explanation, seems warranted. The underlying cause of the symptoms may be an inappropriate spasm of of the distal urethra/external sphincteric unit, leading to increased pressure in the prostatic urethra with a resultant reflux of urine into the prostatic ducts. The presence of urine (sterile or infected) could induce ductal and periductal inflammation, which could further aggravate spasm of the involved pelvic musculature, exacerbating the voiding dysfunction. We present 3 patients in whom this sequence of events was documented radiographically and urodynamically. Consequently, treatment involved modulation of the dysfunction of the distal urethra/external sphincteric unit: (1) reeducation by reassurance and biofeedback was the initial line of therapy; (2) pharmacologic manipulation using alpha-blockers (to affect smooth and striated muscle irritability) and striated muscle relaxants was next tried; (3) finally, in unremitting symptoms, we used selective sacral-root electro-stimulation, successfully fatiguing the involved muscles and relieving the voiding dysfunction.

Adult↗
PubMed1987

The effect of cigarette smoking on penile erection.

Clinical observations suggest that cigarette smoking impairs erectile function in patients with moderate arterial insufficiency. To evaluate the effects of smoking on the physiology of erection, we studied six healthy adult mongrel dogs in which bipolar cuff electrodes were implanted around the cavernous nerves. After threshold stimulation parameters for penile erection were established, cigarette smoke collected in a 60-ml. syringe was released slowly near the dog's mouth, to be inhaled by natural breathing. Stimulation of the cavernous nerve was repeated and blood samples for nicotine, cotinine and blood gases were obtained before and after each cigarette. The systolic and intracorporeal pressure, flow through the internal pudendal artery, and venous flow from the corpora cavernosa were recorded at baseline and with each electrostimulation after smoke inhalation. Five of the six dogs were unable to achieve full erection after inhalation of smoke from two to three cigarettes. Some decrease of flow through the internal pudendal artery occurred and the venous restriction ability was almost completely abolished by smoking. Further, when nicotine was injected intravenously into two additional dogs, the same phenomenon was observed. These findings support the idea that cigarette smoking may contribute to impotence in some patients.

Animals↗
PubMed1987

The role of vasoactive intestinal polypeptide as a neurotransmitter in canine penile erection: a combined in vivo and immunohistochemical study.

Vasoactive intestinal polypeptide (VIP), a 28-amino-acid polypeptide found in the human gut and genitourinary tract, primarily affects vasodilation and smooth-muscle relaxation. These effects have led to speculation that this neuropeptide may be a neurotransmitter in certain bodily functions, such as penile erection. We therefore designed an in vivo animal model to elucidate the influence of VIP and VIP antibody on the different stages of penile erection. We also performed immunohistochemical studies of the penile tissue to obtain further information about the distribution of VIP in the corpora cavernosa. Intracavernous injection of VIP induced penile erection. Its effect on arterial inflow was minor, but it caused active venous outflow restriction and was important in maintaining erection. VIP antibody blocked venous outflow restriction during neurostimulation-induced erection. VIP was found in the cavernous tissue (in the area between the smooth-muscle cells and the sinusoidal spaces) in close proximity to the arteries. We conclude that VIP is a neurotransmitter in the erectile tissue of the penis, and that its effects are similar to those from electrostimulation of the cavernous nerve. VIP increases arterial flow, decreases venous flow, and induces sinusoidal relaxation.

Animals↗
PubMed1987

Chronic papaverine treatment: the effect of repeated injections on the simian erectile response and penile tissue.

To investigate the effect of chronic papaverine treatment, seven monkeys underwent repeated intracavernous injections for one year. One monkey died after 56 injections; the others received a total of 100 each. The strength and duration of erection were recorded after each injection, and the erectile tissue was examined histologically at the end of the study. Over the long term, papaverine maintains its erection-inducing capability, but it does cause pathologic changes in the erectile tissue: minimal to marked fibrosis at the injection site and hypertrophy of smooth muscle in the non-injected area of the corpus.

Animals↗
PubMed1987

Mechanisms of venous occlusion during canine penile erection: an anatomic demonstration.

Hemodynamic studies have clearly demonstrated that intracorporeal injection of papaverine causes an increase of venous outflow resistance, and we therefore undertook a study of the venous drainage of the canine penis to delineate the anatomic changes in the venular structure during papaverine-induced erection. In 11 dogs, the corpora cavernosa were examined by corrosion casting in six and serial trichrome staining and histologic sectioning in five. Low-power scanning electron microscopy of the corrosion casts demonstrated the existence of a venular plexus interposed between the tunica albuginea and the sinusoidal spaces. After papaverine injection, this subalbugineal venular plexus is compressed between the dilated sinusoids from below and the tunica albuginea from above, such that venous drainage is effectively impeded. Examination of two cadaveric human penile corrosion casts by low-power scanning electron microscopy revealed evidence of a similar subalbugineal venular plexus draining into the emissary veins along the shaft of the penis. Based on the above, a model for the anatomic basis of venous occlusion during penile erection is outlined. Along with arteriolar and sinusoidal smooth-muscle relaxation, this can account for the three basic hemodynamic changes necessary for erection: increased arterial inflow, increased intracorporeal pressure, and increased venous outflow resistance.

Animals↗
PubMed1987

Constrictive penile band injury: anatomical and reconstructive considerations.

Cases of constrictive penile band injury are seen often in the emergency room, and most require only removal of the constriction and conservative management. Occasionally, patients present with long-standing constriction, necrosis of the penile tissue and urethral injury. We report 2 such cases. We believe that a thorough understanding of the penile anatomy, aggressive debridement, skin grafting and temporary urinary diversion are essential for successful management of these severe cases.

Adult↗
PubMed1987

Priapism induced by chlorpromazine and trazodone: mechanism of action.

To investigate the mechanism of drug-induced priapism, we gave the antipsychotic agent chlorpromazine and the antidepressant trazodone to 14 dogs by intravenous and intracorporeal injection. Bilateral intracorporeal pressure, blood flow within the internal pudendal artery, and systemic blood pressure were monitored. Venous outflow restriction was evaluated by continuous saline infusion of the corpus cavernosum with the infrarenal aorta clamped. When delivered by intracorporeal injection, both drugs induced erection in a manner similar to that of intracorporeal injection of papaverine. Internal pudendal arterial flow increased slightly at the beginning of tumescence, and excellent venous restriction occurred. Intravenous injection, however, could neither induce an erection nor facilitate an erection after sub-threshold neurostimulation. We believe that the alpha-adrenergic antagonist properties of chlorpromazine and trazodone probably cause priapism by local action.

Animals↗
PubMed1987

New therapy for impotence.

In the not too distant past, the physician caring for the impotent patient had few therapeutic options. With the recent advances in penile pharmacotherapy, vascular surgery, and prosthetics, several possibilities for treatment are now available. Before a decision is made, however, numerous factors must be taken into consideration: age, manual dexterity, cause of erectile dysfunction, psychological attitude, and social considerations. Clearly, the choice of therapy for impotence must now be made on an individual basis after a careful diagnostic evaluation and in-depth consultation with the patient. Only then can the treatment that offers the highest likelihood of success, both functional and emotional, be chosen.

Adrenergic alpha-Antagonists↗
PubMed1987

[The physiology of penile erection. I. Hemodynamics of penile erection].

Arterial and venous flow and pressure studies of the corpora cavernosa were performed to elucidate the hemodynamics of canine penile erection. Being able to induce erection by electrical stimulation we were able to study the functionally relevant parameters at different stages of penile erection. From our results we conclude that penile erection can be subdivided in 5 phases: (1) latent-, (2) tumescence-, (3) erection-, (4) rigidity- and (5) detumescence phase. Furthermore, a differentiation of these subdivisions is made by observing at the mechanism of the 5 different stages: phase 1 to 4 is an active phenomenon, the detumescence phase is passive only.

Animals↗
PubMed1987

[The physiology of penile erection. II. Neurophysiology of penile erection].

Selective cavernous and pudendal nerve stimulation enabled us to study the neurophysiologic-/neurovascular mechanisms of penile erection in 6 monkeys. Corporeal pressure recordings during different neurostimulation patterns demonstrated that tumescence and erection are controlled by the autonomic nervous system (Nn. cavernosi) and has to be understood as the vascular phase of erection. However, rigidity is related to the muscle tone of the striated bulbospongiosus and ischiocavernosus muscles which are innervated by somatomotoric fibers of the pudendal nerve. This mechanism is defined as the muscular phase of penile erection.

Animals↗