Biomedical subjects

P Zvara

Publications and source records attributed to P Zvara.

11 recordsLinked to original sources

PubMed1996

7-Nitroindazole: a selective inhibitor of penile erection: an in vivo study in a rat animal model.

OBJECTIVES: The neuronal isoform of nitric oxide synthase (nNOS) has been localized in neurons innervating the penis and is believed to be an important mediator of erection. Using the selective inhibitor 7-nitroindazole (7-NI), we evaluated the possible role of nNOS in penile erection using a rat animal model. METHODS: Eighteen Sprague-Dawley rats were divided into three study groups. A sham group (n = 6) received the vehicle arachis oil, a low-dose group received 5 mg/kg (n = 6), and a high-dose group received 50 mg/kg (n = 6) of 7-NI prior to measurement of blood pressure and cavernous nerve stimulation-induced rise in intracavernous pressure. RESULTS: A dose-dependent inhibition of erection by 7-NI was seen. Control animals had an intracavernous pressure rise of 55.5 +/- 4.0 cm H2O, whereas the low-dose group had 26.5 +/- 2.8 cm H2O and the high-dose group had 6.2 +/- 2.1 cm H2O. A partial recovery of erection was seen in the low- and high-dose groups after 3 hours. Blood pressure was unaffected by 7-NI administration. CONCLUSIONS: 7-NI induced a reversible, dose-dependent inhibition of erection without affecting blood pressure. This in vivo study provides further evidence of the role played by nNOS in erection.

Analysis of Variance↗

PubMed1996

Neurogenic erectile dysfunction: the course of nicotinamide adenine dinucleotide phosphate diaphorase-positive nerve fibers on the surface of the prostate.

OBJECTIVES: Nitric oxide (NO) plays an important role as a neurotransmitter in the peripheral neural regulation of erection. A histochemical stain able to localize fibers releasing NO in combination with an in vivo study were used to evaluate the course and physiologic significance of the nerve fibers innervating the cavernous smooth muscle. METHODS: Morphologic studies in 6 rats and 6 human cadavers were performed, tracing the course of branches of the cavernous nerve branches using a nicotinamide adenine dinucleotide phosphate diaphorase staining technique. Electrostimulations in rats were performed before and after transection of the anterolateral part of the prostate capsule. RESULTS: Multiple nerve fibers were documented running on the lateral and ventral surfaces of the prostate distinct from the classically described dorsolateral neurovascular bundle. Transection of these fibers resulted in a loss of electrically induced intracavernous pressure (59.4 +/- 5.6 cm H2O versus 27.0 +/- 4.6 cm H2O). CONCLUSIONS: These preliminary morphologic and physiologic studies support a significant role for these nerve fibers in erection.

Animals↗

PubMed1995

Regeneration of nitric oxide synthase-containing nerves after cavernous nerve neurotomy in the rat.

In patients who recover erectile function after radical prostatectomy (with preservation of at least 1 neurovascular bundle), a recovery time of 6 to 18 months is not uncommon. As this is also the usual time required for regeneration of spinal nerves, we believe that regeneration of cavernous nerves, partially damaged inadvertently, may be responsible. In a rat model, we examined the long-term effect of unilateral and bilateral cavernous nerve transection on the nonadrenergic/noncholinergic (NANC) nervous system and erectile function. In 31 rats, nitric oxide synthase (NOS), the enzyme that catalyzes nitric oxide production, was identified in penile nerve fibers from a mid-shaft segment with nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase staining and antibody to neuronal NOS. Animals were divided into three groups: 5 rats underwent pelvic exploration without transection of cavernous nerves (sham group); 13 rats underwent unilateral neurotomy of a 5-mm. segment of the cavernous nerve; and 13 rats underwent bilateral neurotomy. After bilateral ablation, the NOS-positive nerve fibers were significantly decreased at 3 weeks and remained so at 6 months; no erectile response could be elicited by pelvic nerve stimulation. After unilateral ablation, the NOS-positive nerve fibers were similarly decreased on the side of the neurotomy at 3 weeks, but by 6 months the number had increased significantly and approximated the level on the contralateral side. Furthermore, electrostimulation of the intact side induced a greater intracavernous pressure response at 6 months than at 3 weeks (N.B. the rat has an incomplete septum). Fibers positive for NOS were also identified in the dorsal nerve. The staining pattern diminished as rapidly and significantly on the side of neurotomy as in tissue from the corpus cavernosum. However, regeneration was not seen. To our knowledge, this is the first demonstration of regeneration of NOS-containing nerves after cavernous nerve neurotomy. Our findings support the reports by others that unilateral nerve-sparing is sufficient to preserve erectile function.

Amino Acid Oxidoreductases↗

PubMed1995

Transformation of the Bricker to a continent urinary reservoir to eliminate severe complications of uretero-ileostomy performed in eight patients among 200 Bricker.

Between 1969 and 1994 urinary diversion via the ileal loop (Bricker's operation) was performed in 200 patients. After introduction of methods of continent urinary diversion into clinical practice, some of young patients operated in childhood for congenital lower urinary tract malformations demanded the conversion of the primary diversion. The decision was influenced, however, not only by subjective complaints but also by severe complications having relation to the long-lasting presence of stoma. A modified Mainz pouch I, with a catheterizable stoma was constructed in 6 patients with primary uretero-ileostomy made 7 to 22 years prior to conversion because of exstrophy of the urinary bladder or a neurogenic bladder with total urine incontinence. The ileal loop used for uretero-ileostomy was detubularized or combined with additional segments of ileum and colon. The ileal stoma was connected to the umbilicus. In other two patients suffering from a neurogenic bladder the uretero-ileostomy was converted to an orthotopic ileal pouch. The authors present long-term results (1.5 to 7 years) of follow-up with urodynamic and radiological evaluation. The results both compensate the urologist's efforts and enhance the patient's quality of life.

Adolescent↗

PubMed1994

Laparoscopically implantable nerve-stimulating electrode (LINSE): application to the cavernous nerve in acute and chronic canine models.

Using a new laparoscopic procedure, we investigated stimulation of the cavernous nerves to achieve erection in a canine model. The technique was developed during acute experiments in four dogs, following which, chronic studies (4- to 6-weeks survival after surgery) were undertaken in three dogs. A monopolar cuff electrode was inserted laparoscopically by a transperitoneal approach and placed around the cavernous nerve. The leads were brought out to the subcutaneous space, where they were attached to stimulation receivers that could be activated by an external radiofrequency transmitter. An intracavernous pressure elevation indicative of successful stimulation was obtained acutely in five of eight cavernous nerves in the four acute-study dogs and in four of six nerves in the three chronic-study dogs. The implanted equipment associated with four of six cavernous nerves failed mechanically in the chronic-study animals, such that only two receiver-electrode sites were intact at the time of sacrifice 4 to 6 weeks later. Transmitter-driven stimulation of one of these two sets produced an intracavernous pressure rise above 100 cm H2O. We present this technique as part of the continuing evolution of laparoscopy as both a research and a clinical tool. The present use of the laparoscopically implantable nerve-stimulating electrode is a new animal research tool and a potential first step in the human application of the technology.

Animals↗

PubMed1994

The detailed neuroanatomy of the human striated urethral sphincter.

OBJECTIVE: To study the nerve supply of the striated urethral sphincter. MATERIALS AND METHODS: The pelvis from six formalin-fixed male cadavers was dissected. RESULTS: Cadaveric dissection revealed that both the intrinsic and extrinsic segments of the urethral rhabdosphincter receive their innervation from sacral roots S2-S4. The nerve fibres travel to their final destination via both the pudendal nerves and the nerve branches of the sacral roots. The terminal branches of the pudendal nerve enter the sphincteric area from the perineum. They separate shortly after they cross the ischial spine and run further ventromedially. Small branches approach the sphincter after their division from the dorsal nerve of the penis. The course of the pudendal nerve and its branching on the perineum are quite consistent. The pelvic branches travel inside the pelvis above the levator ani muscle. Among the cadavers the number of branches varied markedly, as did their site of termination (2.3 to 3.9 cm from the striated urethral sphincter). A substantial nerve approaching the sphincter from inside the pelvis was found. After it divided from the S2, S3 sacral roots it ran separately, initially just lateral to the fibres of the pelvic plexus and then on the dorsolateral surface of the rectum. In its terminal segment it dived into the levator ani muscle and terminated in the striated urethral sphincter. CONCLUSIONS: We believe that the nerve supply to the striated urethral sphincter consists of branches from both the pudendal nerve and the 'extrapudendal' nerves that run above the levator ani muscle inside the pelvis. The variations in the course of the latter are remarkable.

Humans↗

PubMed1994

Erectile dysfunction.

A better understanding of penile physiology and pathophysiology has revolutionized the diagnosis and treatment of erectile dysfunction in the past decade. This article summarizes the current knowledge and presents a patient's goal-directed approach to the evaluation and treatment of erectile dysfunction.

Erectile Dysfunction↗

PubMed1993

[Electrostimulation of the urinary bladder].

The authors present their first results with urinary bladder stimulation in dogs by using an electronic stimulator and electrodes of their own construction. Neurostimulation was carried out by means of contactless application of electrical rectangular pulses with the voltage ranging from 1 to 10 volts, frequency from 10 to 300 Hz and pulse with 1 ms. Due to the stimulation of the branches of the pelvis plexus an isolated contraction of the bladder detrussor with an increase of intravesical pressure up to 65 cm H2O was observed with subsequent spontaneous voiding. The stimulation of the intact sacral root S2 led to detrussor-sphincteric dyssynergia caused by simultaneous contraction of the detrussor and the striated urethral sphincter. The poststimulus spurt of urine was observed at the end of each S2 stimulation. The authors inform about the further plan of experimental work before introducing the method into clinical practice. (Fig. 4, Ref. 17.).

Animals↗

PubMed1993

[Erectile dysfunctions in patients treated with hemodialysis and kidney transplantation].

The incidence of erectile dysfunction in patients suffering from severe renal diseases in the stage of renal insufficiency is significantly higher in comparison with healthy men of the same age. In the etiopathogenesis of erectile disorders, both organic and psychogenic factors participate in combination. By means of a questionnaire, the authors have collected information from 53 men treated by hemodialysis and kidney transplantation because of renal failure. Erectile disorders occurred in 41.5 per cent of men with chronic renal insufficiency. On one side hemodialysis improved the erectile dysfunction in two patients, in total, however, the incidence of impotence increased to 64.2 per cent. Erectile dysfunction was reported by 71.7 per cent of patients after kidney transplantation. The authors describe two cases of iatrogenic arterial insufficiency of the penis as the cause of impotence after secondary renal transplantation. In uremic patients as possible therapeutic methods, intracavernous application of vasoactive drugs or penile prostheses implantation should be considered. (Fig. 2, Ref. 20).

Adult↗

PubMed1992

[A screening program for the diagnosis of early forms of prostatic carcinoma].

Carcinoma of the prostate is at present one of the most frequently occurring malignancies in the male population. The disease can be cured only at the early stage when it has not yet spread beyond the limits of the gland. Early, clinically asymptomatic forms of carcinoma of the prostate can be diagnosed only by screening examinations of men. The justification of screening has, however, not been conclusively established and the fear of damaging the patient on examination could not be dispelled. The project of an international co-operative study was accepted in Stockholm in 1990 with the aim to address this question. The Department of Urology of Derer's Hospital with Policlinic, along with several urological, oncological, and research departments, have decided to join the project in order to contribute to the improvement of diagnosis and treatment of carcinoma of the prostate. (Fig. 1, Ref. 12.).

Humans↗

PubMed1992

[Urinary diversion by means of uretero-ileostomy. Long-term results].

The authors analyze a group of 187 patients where in 1969-1991 a ureteroileostomy was performed on account of malignant tumours (89.8%) or other diseases (10.2%). Ureteroileostomy was indicated along with cystectomy in 77 patients with tumours of the urinary bladder (63 times), with gynaecological carcinoma (21 times) and in tumours of the urethra and rectum (7 times). Indications in non-tumours diseases comprised a neurogenic bladder (10 times) exstrophy of the urinary bladder (6 times), post-traumatic incontinence of urine in women (twice) and iatrogenic injuries of the ureters (once). In all patients an anastomosis between the ureter and excluded loop, as described by Wallace, was used. The surgical mortality was 5.3%. During the immediate postoperative period 96 complications developed in 91 (51.3%) patients. As to late complications, most frequently complications of the stoma of the excluded loop were involved. Ureteroileostomy gives satisfactory results in the majority of patients, however, the number of complications is not negligible. The authors discuss the selection of derivation methods under our conditions.

Adolescent↗