Biomedical subjects
Publications and source records attributed to K Hirayama.
We report on 2 girls with a terminal deletion of the short arm of chromosome X. They had microphthalmia, cloudy corneae, mild linear skin lesions, and agenesis of corpus callosum. A comparison of clinical and cytogenetic findings in similar cases suggested that the critical genes for the Goltz and Aicardi syndromes might be contiguous in the region Xp22.31.
Liver microsomes were prepared from Wistar rat by the Ca2+ aggregation method. Under various conditions, ethyl mercury chloride (EtHgCl) or methyl mercury chloride (MeHgCl) was incubated with the microsomal preparations. After the incubation, the amounts of inorganic Hg and hydroxyl radical (.OH) in the preparations were determined. Although the preparations alone produced a small amount of inorganic Hg and .OH, the addition of NADPH to the preparations increased both inorganic Hg and .OH production, which were further accelerated by the addition of KCN. The addition of Fe(III)EDTA, a .OH formation promoter, to the microsome-NADPH-KCN system increased inorganic Hg production, whereas the addition of diethylenetriamine pentaacetic acid, a .OH formation inhibitor, decreased inorganic Hg production. When .OH scavengers such as mannitol and dimethyl sulfoxide were added to this system, the inorganic Hg production decreased. These results suggested that the .OH produced from liver microsomes was responsible for the degradation of MeHg and EtHg. Since both .OH and inorganic Hg production decreased with a concomitant decrease in NADPH-cytochrome P-450 reductase activities, it is suggested that this enzyme may be involved in the microsomal degradation of MeHg and EtHg.
Cardiovascular effects of the crowns-of-thorns starfish (Acanthaster planci) venom were examined in rats. The crude venom extracted from the spines of A. planci caused systemic hypotension associated with an increase in heart rate and a decrease in renal cortical blood flow when given i.v. The hypotensive effect of the venom was not inhibited by pretreatment with atropine, indomethacin or aprotinin, but was significantly inhibited by SRI 63-441, a platelet activating factor (PAF) antagonist. The venom caused dose-dependent vasorelaxation of the isolated rat aortic ring preparation precontracted by noradrenaline, an effect which was significantly attenuated by pretreatment with SRI 63-441, methylene blue or parabromophenacyl bromide. Denudation of the endothelium also diminished the vasorelaxing effect of the venom. Both the vasorelaxing and the hypotensive effects showed tachyphylaxis. These results suggest the release of PAF or a PAF-like substance from the endothelium by the venom.
We investigated the influence of dietary protein levels on the fate of methylmercury (MeHg), the tissue glutathione (GSH) levels and the efflux rates of GSH in C57BL/6N male mice. One group of mice was fed a 7.5% protein diet (low protein diet, LPD) and the other was fed a 24.8% protein diet (normal protein diet, NPD). The cumulative amount of Hg in urine in LPD-fed mice was approximately 3.7-times lower than in NPD group during the 7 days after oral administration of MeHg (20 mumol/kg), although the fecal Hg levels were identical in the two groups. Hg concentration in kidney, liver and blood decreased time-dependently for 7 days after the administration in both groups of mice, whereas the brain levels continued to increase during this period. Tissue Hg levels in the LPD group were significantly higher than in the NPD group except for the liver. Although the hepatic GSH level in LPD-fed mice was significantly lower than in NPD-fed mice, the levels in the kidney, brain, blood and plasma were not different between the two groups. The efflux rate (mumol/g body weight per day) of hepatic GSH in LPD-fed mice was significantly lower than in the NPD group, whereas the efflux rates of renal GSH were identical in both groups. When MeHg (20 mumol/kg)-pretreated mice were injected with acivicin, a specific inhibitor of gamma-glutamyltranspeptidase, the urinary Hg levels increased by 60- and 36-fold in groups fed LPD and NPD, respectively. As a result, the difference in urinary Hg levels between the two groups disappeared with acivicin treatment. This result indicated that LPD feeding might decrease urinary Hg excretion by increasing the retention of MeHg metabolite(s) in renal cells. Thus, our present study suggested that the dietary protein status, which could modulate the metabolism of thiol compounds, played an important role in determining the fate of MeHg.
We report the case of a 55 year-old right-handed man who presented with a long lasting pure word deafness following left thalamic bleeding. There was no sign of aphasia. The auditory deficit was specific for language, while recognition of music and environmental sounds was normal. CT, MRI and PET examinations showed that the lesion was anatomically and functionally confined to the left cerebral hemisphere, mainly the white matter of the temporal and parietal lobes. Wernicke's area was largely preserved. It is proposed that pure word deafness was consequent to the isolation of Wernicke's area from incoming auditory information due to the interruption both of the association fibers from the right auditory area traveling across the corpus callosum and of the left auditory radiations.
Neurourological studies were performed on 15 patients with tumors at or below the first lumbar vertebra. Micturitional history revealed that 14 patients (93%) had voiding symptoms. Four patients had incontinence and three had urinary retention. Urodynamic studies revealed that three of six patients tested had abnormal uroflowmetrograms. Urinary residuals greater than 100 ml were observed in 6 of 12 patients. Detrusor hyperreflexia occurred in 3 of 15 patients, 4 of 15 had low-compliance detrusor, and 2 of 15 had detrusor-sphincter dyssynergia. There were no differences in lower-extremity neurological signs in patients with or without incontinence, and patients with or without large residual urine and urinary retention.
A micturitional history of unselected 110 patients with Parkinson's disease revealed that 66 (60%) had urinary symptoms such as irritative in 28%, obstructive in 11%, and both symptoms in 21%. The frequency of urinary symptoms statistically correlated with severity of the disease, but not with the duration of illness and no sexual difference was noted. A urodynamic study was conducted in 39 patients and 7 had residual urine of 30 ml or more, 19 had detrusor hyperreflexia, 19 had a small bladder capacity and only 1 had detrusor-sphincter dyssynergia. The results indicate that the disturbed urine storage is more frequent and to a severer degree than that of urine evacuation in Parkinson's disease.
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We have examined the turnover of 5,6,7,8-tetrahydrobiopterin (BH4) and the effect of decreasing BH4 levels on in situ tyrosine hydroxylase (TH) activity and norepinephrine (NE) content in a homogeneous population of NE-containing neurons derived from the superior cervical ganglion (SCG) of the neonatal rat and maintained in tissue culture. Initial studies indicated that the level of BH4 within SCG cultures increased fourfold between 5 and 37 days in vitro (DIV). This increase in BH4 levels was determined to result from an increase in the rate of BH4 biosynthesis without a change in the rate of degradation. Regardless of culture age, the BH4 content of SCG neurons was observed to turn over with a half-life of approximately 2.5 h. BH4 synthesis by SCG neurons was found to be five times more sensitive to inhibition by 2,4-diamino-6-hydroxypyrimidine (DAHP) and 25 times less sensitive to inhibition by N-acetylserotonin than was previously reported for CNS neurons in culture. Under basal conditions, the rates of in situ TH activity and BH4 biosynthesis were similar. In response to inhibition of BH4 biosynthesis by DAHP and a 90-95% decrease in BH4 levels, in situ TH activity declined by 75%. NE levels declined by 30% following a 24-h period of inhibition of BH4 synthesis. After 2 days of BH4 synthesis inhibition, the level of NE was decreased by 47%. On treatment days 3 and 4, the decline in NE content plateaued at 24% of control levels.(ABSTRACT TRUNCATED AT 250 WORDS)
A 67-year-old woman developed central pain in the face with bilateral horizontal gaze palsy following brainstem encephalitis. Magnetic resonance imaging demonstrated a lesion in the pontobulbar tegmental area.
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The recurrence of esophageal cancer involving regional nodes, even in patients who have undergone curative surgery, often takes place within three years after surgery. Thus, a new multidisciplinary treatment including cytokines or aggressive chemotherapy with active nutritional support to improve the prognosis in cancer of the thoracic esophagus has been adopted.
We report on a 41-year-old woman with slowly progressive motor dominant polyneuropathy, optic atrophy and sensorineural deafness, but without any known familial feature. These neurological manifestations were in accordance with the syndrome reported by Rosenberg and Chutorian in 1967 (Rosenberg-Chutorian syndrome), a unique form of Charcot-Marie-Tooth disease. The syndrome was first reported to be autosomal dominant in trait, but subsequently recessive forms and sporadic ones have also been described. Nerve biopsy and neurophysiological studies including electromyography, nerve conduction velocities, somatosensory evoked potentials, auditory brainstem responses, and visual evoked potentials revealed the axonopathic involvement of the central nervous system as well as the peripheral nervous system. Since neurophysiological aspects of this particular syndrome have not been well studied, these results would provide some insight into the understanding of this disorder.
Clinical findings were studied in 50 patients with 53 lesions of solar keratosis encountered during the 15 year period from 1977 to 1991. The majority of these cases were evident in the over-sixty age group (average 62.2 years). A greater proportion were females. Most lesions were observed on the face; especially on the cheek, and from the outer eyelid to the temple. The erythematous type (desquamative-keratotic) lesion was the most evident. With the exceptions of the years 1979 and 1991, no remarkable increase in the number of patients was noted during the 15 year period.
We examined histopathologic data from 50 patients with 53 lesions of solar keratosis encountered over the past 15 years (1977 to 1991). The epidermis showed acanthosis, uneven epidermal dyeing properties, disorderly arrangement of the basal cells, atypia of the nucleus, mitotic figures and hyperpigmentation of the basal layers. The dermis showed actinic elastosis, cell infiltration mainly consisting of the lymphoid cells, and incontinentia pigmenti histologica. Among histologic types, the hypertrophic type was the primary example.
Non-progressive juvenile spinal muscular atrophy of the distal upper limb (Hirayama's disease) occurs predominantly in men in the second decade with unilateral weakness of the fingers and hand, and atrophy of the hand and forearm. The symptoms generally progress for 3-4 years after onset and then stop. Since the second decade is a very important period starting one's career, early stopping of the progression and possibly the improvement are essential. On the bases of the neuroradiological studies, a forward displacement of the posterior wall of the dural canal at the lower cervical level on neck flexion is presumed to be the main pathogenetic mechanism in this disease. On neck flexion, the spinal cord is compressed anteroposteriorly at C7 and C8 segmental levels. Pathological studies suggested that chronic microcirculatory disturbances in the spinal cord as the result of repeated flexion of the neck might produce necrosis of the anterior horns. We used a cervical collar for the prevention of neck flexion in 14 patients in the early stage and compared the results with those of 18 patients who had natural courses. In the therapy group, muscle weakness of the affected hand improved in 5 patients and the progression of the disease was stopped in 8 patients with the duration of 1.8 +/- 1.2 years, whereas the duration of progression of the natural course group was 2.9 +/- 1.6 years. Only one patient who could not tolerate the use of collar showed a slight progression. These results suggest that the cervical collar is a useful therapeutic tool in this disease.
We reported a case of 89-year-old woman showing rhythmic skeletal myoclonus mainly on the right upper limb. This myoclonus appeared five days after the cerebral infarction. It was seen constantly both at rest and in posture, and decreased during voluntary movement. When the patient was under emotional stress, it spread to the submandibular, neck and trunks of upper limb. During sleep, this movement completely disappeared. There was no myoclonus in palato-pharyngo-laryngo-oculo-diaphragmatic muscle group. In the examination of the surface electromyography, the movement was not reciprocal between extensor and flexor muscles, and its cycle was about 3.5 Hz. It was different from the intention tremor because it did not increase during the movement phase on the finger nose test. The examination of MRI revealed a small infarction including right dentate nucleus and right superior cerebellar peduncle, and from which an infarction of the superior cerebellar artery territory was considered. Only a few cases of rhythmic skeletal myoclonus without palatal myoclonus have been reported in the literature. All of these cases had small infarction of the same region as the above case. Their myoclonus began 5 to 15 days after the onset of cerebral infarction. These periods were markedly shorter than that of intention tremor and palatal myoclonus. This fact suggest that the rhythmic skeletal myoclonus has a different mechanism from that of the palatal myoclonus.
We investigated the clinical features of 179 patients with late cortical cerebellar atrophy (LCCA) comparing with 382 patients with olivo-ponto-cerebellar atrophy (OPCA) and 91 patients with hereditary cortical cerebellar atrophy (HCCA) using multivariate analysis. They had no significant difference in durations from onset. Disorders of finger-nose test were of more severity and disorders of heel-knee test were less involved in LCCA than in HCCA. Eye movements tended to be normal in LCCA. LCCA showed more depressive and euphoric character than OPCA and HCCA. Analysis of LCCA and OPCA demonstrated that LCCA revealed hypotonia in muscles, normal or weak reactions of muscle stretch reflexes. There existed 21.4 percent of cases which could not be discriminated by multivariate analysis using clinical signs in LCCA and OPCA. Multivariate analysis of LCCA and HCCA, which are very similar in clinical signs, showed 66.3 percent of discriminatory rate. Thus, we could diagnose them to a certain extent only by clinical signs.