Masanobu Miyata

A Study Of Micturition Inducing Sites In The Periaqueductal Gray Of The Mesencephalon

PURPOSE The mesencephalon, especially the periaqueductal gray, is believed to integrate specific movement patterns of the somatic and autonomic nervous system, including those of vocalization, defensive behaviors and others. Fiber communications exist between the periaqueductal gray and the pontine micturition center, and many nerve fibers ascending from the sacral spinal cord project to the periaqueductal gray. We examined whether the mesencephalon is involved in micturition function using microstimulation and a neurotracer. MATERIALS AND METHODS We decerebrated 28 adult cats under general anesthesia. An electrode that can be used for microinjection was positioned in stereotaxic fashion in the mesencephalon and pons. Subsequently electrical stimulation and chemical stimulation with DL-homocysteine acid were applied to search for micturition inducing sites. Blood pressure and respiration were monitored simultaneously. We also performed electrical microstimulation of pontine micturition center. The neurotracer 5% Fluoro-Gold (Denver, Colorado) was injected into these sites to identify neural pathways between the mesencephalon and pons. The brainstem was removed after 10 hours and the mesencephalon was examined by fluorescence microscopy. RESULTS Bladder contraction was provoked by electrical and chemical stimulation applied mainly at the ventrolateral side of the periaqueductal gray. Blood pressure increased simultaneously with bladder contraction after periaqueductal gray stimulation. Neurotracer injected into the pontine micturition center was found mainly on the ventrolateral side of the periaqueductal gray, in agreement with the sites where micturition was provoked by microstimulation. CONCLUSIONS Nerve cells on the ventrolateral side of the periaqueductal gray have neural communications with the pontine micturition center bilaterally and they regulate micturition.

Coexistence of Fast and Slow Myosin Isozymes in Human External Urethral Sphincter. A Preliminary Report

Human external urethral sphincter muscle was isolated for biochemical research. Myosin samples were prepared and pyrophosphate gel electrophoresis and two-dimensional electrophoresis were performed. Assignment in pyrophosphate gel of myosin isozymes of human external urethral sphincter was carried out by making comparisons with those from human rectus abdominis muscle. Myosin light chains in human external urethral sphincter were identified using two-dimensional electrophoresis. Human external urethral sphincter, similar to other voluntary muscles, is composed of fast and slow twitch muscle fibers, since fast and slow myosin components were shown in both pyrophosphate gel and two-dimensional electrophoretograms.

A Maternal Functioning Adrenocortical Adenoma Causing Fetal Female Pseudohermaphroditism

Fetal virilization induced by a maternal adrenal tumor is extremely rare. We report a case of a maternal adrenocortical tumor with Cushings syndrome causing fetal virilization.

Pelvic nerve grafts restore bladder function in denervated rats

BACKGROUND Autonomic nerve preservation techniques for use during surgery for rectal cancer have improved. Nevertheless, in some patients pelvic nerves must be sacrificed to excise all tumor. For these patients, nerve reconstruction at the time of operation by using nerve grafting would be useful. A rat model of this type of nerve reconstruction is described. METHODS Animals were divided into three groups. In the sham control group, a pelvic exploration was conducted without division of the pelvic nerves. In the nerve ablation group, both pelvic nerves were excised segmentally. In the graft group, both pelvic nerves were excised and genitofemoral nerves were interposed bilaterally. At 2-week intervals postoperatively, animals from each group underwent cystometry under urethane anesthesia and neuronal tracing using fragment C of tetanus toxin for demonstration of axonal transport via regenerated nerves. RESULTS At 6 weeks postoperatively, 60% of the grafted animals produced rhythmic contractions of the bladder. In neuronal tracing studies at weeks 4 and 6, respectively, 40% and 100% of the nerve-grafted rats had labeled neurons in the sacral parasympathetic nucleus. CONCLUSIONS These findings suggest that pelvic nerve grafting in rats can successfully restore bladder function after surgical injury. Clinical use of pelvic nerve grafting may be indicated for patients whose pelvic nerves must be sacrificed to excise all tumor.

NEUROPATHIC BLADDER DYSFUNCTION IN PATIENTS WITH OSSIFICATION OF THE POSTERIOR LONGITUDINAL LIGAMENT

Background: Ossification of the posterior longitudinal ligament (OPLL) may cause neuropathic bladder dysfunction due to spinal cord involvement. OPLL, unlike a traumatic spinal cord lesion, progresses insidiously and sometimes affects longer cord segments. As the manifestation of bladder dysfunction may depend on the development of OPLL, we studied the relationship between bladder function and roentgenographic changes in the spinal canals of OPLL patients.

Automatic Analysis of Urethral Electromyography for Accurate Diagnosis of Voiding Dysfunction

An electromyogram contains much more information than observed in the gross pattern of an electromyogram simultaneously recorded with a cystometrogram. Being able to pick up some of the information would be helpful in the accurate diagnosis of ambiguous patients showing a discrepancy between clinical symptoms and laboratory data. This study analyzed electromyograms of the urethral and anal sphincter during the filling phase of the cystometrogram by means of automatic turns-amplitude analysis with a computer-assisted analyzer. In normal subjects, turns and amplitudes of an urethral electromyogram had increased frequency and size as the subjects felt a greater sensation of fullness. In patients with abnormal vesical function, the characteristics of the urethral electromyogram varied. Some of the patients with normal vesical activity and coordinated urethral sphincter, though their clinical symptoms strongly suggested neuropathic vesical dysfunction, showed a low frequency and low amplitude pattern of the urethral sphincter electromyogram. Anal sphincter electromyogram did not always show the same patterns as the urethral sphincter even in the normal subjects. The turns-amplitude analysis of urethral sphincter electromyogram will be of use for accurate diagnosis of vesical dysfunction.

Studies on the hemodynamics of erection by electrostimulation of the cavernous nerves in the dog

To study various aspects of penile erection, we created dog models by implanting electrodes around the cavernous nerves. The cavernous nerves, which are branches of the pelvic plexus, travel along the posterolateral aspect of the prostate to innervate the erectile tissue of the penis. We studied to evaluate the details of the hemodynamic changes of penile erection. The studies included: 1) internal pudendal arterial blood flow, 2) intrapenile blood flow, 3) corporeal pressure and 4) femoral blood pressure. Immediate response to stimulation was an increase in blood flow in the internal pudendal arteries. The latent period lasted for approximately 10 to 20 seconds. The flow increase occurred in both systolic and diastolic phases. After the latent phase, intracorporeal pressure rapidly increased and approached the level of the diastolic blood pressure. When the full erection was achieved, the flow still remained above prestimulation level, although a gradual decrease in the flow was seen. Intrapenile blood flow was silightly decreased at the time of full erection, compared with that of non-erection. Tumescence of the corpora cavenosa was found to be a result of active relaxation of the sinusoidal spases and active arteriolar dilatation.