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Kimihito Arai

Publications and source records attributed to Kimihito Arai.

14 recordsLinked to original sources

Urinary dysfunction and autonomic control in amyloid neuropathy.

Uro-neurological assessment was performed in four patients with small-fiber neuropathy due to amyloidosis (2 transthyretin-type/2 immunoglobulin light-chain-type). Voiding difficulties were due to detrusor weakness and impaired bladder sensation. In two patients cholinesterase inhibition treatment caused urge incontinence, indicating detrusor denervation supersensitivity. The underlying mechanisms of urinary dysfunction seem to involve postganglionic cholinergic and afferent somatic nerves.

Aged↗

Rho-kinase inhibition enhances axonal regeneration after peripheral nerve injury.

In injured adult neurons, the process of axonal regrowth and reestablishment of the neuronal function have to be activated. We assessed in this study whether RhoA, a key regulator of neurite elongation, is activated after injury to the peripheral nervous system. RhoA is activated in motoneurons but not in Schwann cells after mouse sciatic nerve injury. To examine whether the activation of RhoA and its effector, Rho-kinase, retards axon regeneration of injured motoneurons, we employed a Rho-kinase inhibitor, fasudil. Amplitudes of distally evoked compound muscle action potentials are increased significantly faster after axonal injury in mice treated with fasudil compared with controls. Histological analysis shows that fasudil treatment increases the number of regenerating axons with large diameter, suggesting that axon maturation is facilitated by Rho-kinase inhibition. In addition, fasudil does not suppress the myelination of regenerating axons. These findings suggest that RhoA/Rho-kinase may be a practical molecular target to enhance axonal regeneration in human peripheral neuropathies.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

Epilepsia partialis continua as an isolated manifestation of motor cortical dysplasia.

Cortical dysplasia has been increasingly recognized as a cause of epilepsy. We describe herein a 31-year-old female patient with epilepsia partialis continua (EPC) in the right extremities, which had lasted for 15 years without generalized seizures and other neurological deteriorations. MRI showed a focal thickening around the left motor area, indicative of cortical dysplasia, with adjacent subcortical abnormal T2 high intensity, suggestive of dysmyelination. Transcranial magnetic stimulation revealed low motor thresholds and markedly prolonged latencies of motor-evoked potentials (MEP) of the affected side, consistent with hyperexcitability of the cortical motoneurons accompanied by dysmyelination. This case demonstrates that motor cortex dysplasia can result in a mild and non-progressive form of epilepsia partialis continua, associated with the characteristic MRI and MEP abnormalities.

Adult↗

Lower urinary tract dysfunction in Machado-Joseph disease: a study of 11 clinical-urodynamic observations.

OBJECTIVES: Machado-Joseph disease (MJD), or hereditary spinocerebellar ataxia type 3, is the most common dominantly inherited ataxia. However, lower urinary tract (LUT) dysfunction in MJD has not been fully delineated. We investigated LUT dysfunction in MJD by clinical-urodynamic observations. METHODS: In 24 genetically diagnosed MJD, we recruited all 11 patients with LUT symptoms (six men, five women; age, 18-61 [mean 48] years; disease duration, 2-24 [mean 9] years; voiding difficulty, 7, urinary incontinence, 4). Urodynamic studies consisted of uroflowmetry, measurement of post-void residuals and electromyography (EMG)-cystometry. Neurophysiology tests consisted of motor unit potential (MUP) analysis of the sphincter and extremity muscles, tibial nerve somatosensory evoked potentials (SEP) and nerve conduction studies (NCS) of the extremities. RESULTS: Urodynamic abnormalities were seen in all 11 patients studied. Maximum or average flow rate was decreased in five. Post-void residual was noted in three but residual urine volume > 100 ml was noted in only one patient. Maximum urethral closure pressure was low in one and high in one of five patients studied. EMG-cystometry during filling showed detrusor overactivity in five, impaired bladder sensation in four, low compliance detrusor in one, uninhibited sphincter relaxation in one and incompetent urethra in one. Voiding phase abnormalities included detrusor areflexia in three and detrusor-sphincter dyssynergia in two. Bethanechol supersensitivity of the bladder was noted in one of three patients studied. Bulbocavernosus reflex was absent in two of five patients studied. MUP analysis showed neurogenic changes in six of nine sphincter muscles and in all six extremity muscles studied. Five patients had prolonged or absent cortical response in SEP and four had sensory axonal neuropathy in NCS, which were relevant to the impaired bladder sensation. CONCLUSION: In the present study, a half of MJD patients had LUT symptoms and they showed various urodynamic abnormalities. Detrusor overactivity, impaired bladder sensation, and neurogenic sphincter EMG were common findings, and large post-void residuals were rare. These findings are relevant to central and peripheral nervous system pathology of MJD.

Adolescent↗

Study of the rostral midbrain atrophy in progressive supranuclear palsy.

Rostral midbrain atrophy in progressive supranuclear palsy (PSP) is detected by mid-sagittal plain magnetic resonance imaging (MRI). The shape of the atrophy looks like the bill of a hummingbird (hummingbird sign). We studied this sign to elucidate the nature of midbrain atrophy in PSP. Eight patients with PSP, 12 with Parkinson's disease (PD), and 10 normal controls were studied. Using mid-sagittal plain MRI, we measured the rostral and caudal midbrain tegmentum (MT), superior and inferior colliculus, pontine base, and tegmentum. We compared the length of the interpeduncular fossa, which is posterior to the mammillary body, to the diameter of the midbrain tegmentum. The multiple comparison method was used for the statistical analysis. The hummingbird sign was demonstrated in all of the PSP patients studied, and it was not observed in PD patients nor in normal controls. The hummingbird sign in the PSP patients was due to the atrophy of the midbrain tegmentum (rostral and caudal) and to a relative increase in the length of the interpeduncular fossa over that of the anteroposterior diameter of the midbrain tegmentum. The hummingbird sign, which represents the atrophy of the rostral midbrain tegmentum, strongly suggests the involvement of the rostral interstitial nucleus of the medial longitudinal fasciculus in patients with PSP. Demonstration of a hummingbird sign on MRI is thought to be useful for a diagnosis of PSP.

Aged↗

Leukocytoclastic-vasculitic neuropathy associated with chronic Epstein-Barr virus infection.

We report a patient with leukocytoclastic-vasculitic neuropathy associated with chronic Epstein-Barr virus (EBV) infection. A 55-year-old man had been suffering from chronic progressive axonal polyneuropathy and skin erythema for 3 years. A skin biopsy showed capillary vasculitis with clustered leukocyte fragments. Findings of serum assays, a polymerase chain reaction for EBV-DNA, and in situ hybridization indicated chronic EBV infection. Immunosuppressive treatment resulted in the gradual lessening of his general and neurologic symptoms.

Biopsy↗

SPECT abnormalities with unilateral arm dystonia in a young mentally retarded apprentice cook: contralateral thalamo-cortical dysfunction.

We report a young, mentally retarded apprentice cook with a 2-month history of right upper extremity dystonia, for whom diazepam therapy was efficacious. We evaluated brain perfusion by single photon emission tomography (SPECT) before and after diazepam treatment. The abnormal hyperperfusion in the left thalamus and hypoperfusion in the left frontal cortex were normalized on the second SPECT under the successful diazepam treatment. These findings were indicative of functional changes in the left thalamus and left frontal cortex.

Adult↗

Biopterin metabolism in patients with malignant syndrome.

We examined the autopsied brains of two parkinsonian patients who had malignant syndrome (MS). Neopterin and biopterin contents, and GTP cyclohydrolase I activity were measured in various region of the brain. We found relatively higher GTP cyclohydrolase I activities in the hypothalamus compared with other regions of the brain from patients with MS. This finding suggested a possible involvement of biopterin metabolism in pathophysiology of MS. This is the first report on biopterin metabolism in the brains of patients with MS.

Aged↗

Muscle cramp in Machado-Joseph disease: altered motor axonal excitability properties and mexiletine treatment.

Machado-Joseph disease is one of the most common hereditary spinocerebellar degenerative disorders with a wide range of clinical manifestations. Pathology studies have shown mild to moderate loss of anterior horn cells and, in terms of spinal pathology, Machado-Joseph disease is regarded as a type of lower motoneuron disease. Muscle cramps are often associated with lower motoneuron disorders, but features of cramps in Machado-Joseph disease patients have never been studied. We investigated the incidence and nature of muscle cramps in Machado-Joseph disease patients, the excitability properties of motor axons [strength-duration time constant (tau(SD)), threshold electrotonus, refractoriness and supernormality] using threshold tracking and the effects of mexiletine hydrochloride on those cramps. Of 20 consecutive patients, 16 (80%) had frequent, severe muscle cramps in the legs, trunk or arms that disturbed their daily activities. The frequency of pathological muscle cramps was similar to that for patients with amyotrophic lateral sclerosis (68%) and higher than those for patients with spinal muscular atrophy (33%) or peripheral axonal neuropathy (24%). Threshold-tracking studies showed that tau(SD), which in part reflects Na(+) conductance at the resting membrane potential, was significantly greater in the Machado-Joseph disease patients than in normal subjects; severe muscle cramps were associated with a longer tau(SD). Threshold electrotonus, refractoriness and supernormality were not significantly different between Machado-Joseph disease patients and normal subjects. Eight Machado-Joseph disease patients with severe cramps, who received mexiletine treatment, experienced nearly complete relief with a partial normalization of tau(SD) (P = 0.08). Muscle cramps are a very frequent and disabling factor in Machado-Joseph disease. Pathological muscle cramps responded well to mexiletine treatment, and this is consistent with the hypothesis that they are caused by an increase in persistent Na(+) conductance, possibly associated with axonal regeneration or collateral sprouting.

Adolescent↗

Laryngeal stridor in multiple system atrophy.

The purpose of this study was to elucidate the clinical features of laryngeal stridor in 104 patients with multiple system atrophy (MSA) and to predict the hazard risk. Stridor was observed in 36 patients. It occurred in the first year of the disease in 10 cases, and 69% of the cases were diagnosed with stridor within the first 4 years. Dysphagia and hoarseness had a statistically higher frequency in the stridor group, and the onset period of these elements correlated with the onset of stridor. A follow-up study of survival probability was carried out in 83 patients. The median survival period in the stridor group (33 cases) and the non-stridor group (50 cases) was 8.0 and 9.0 years, respectively. Treatment for stridor decreased the relative risk from 2.998 to 0.147. Laryngeal stridor is a common and early clinical symptom in MSA. Early treatment for stridor is advisable to reduce mortality.

Adult↗

Influences of intranuclear inclusion on nuclear size - morphometric study on pontine neurons of neuronal intranuclear inclusion disease cases.

In looking for a possible influence of nuclear inclusions (NIs) on neurodegeneration in human brains, we quantified morphological features of pontine neurons of three unrelated cases of neuronal intranuclear inclusion disease (NIID) and five control cases. Cross-sectional area of each neuronal nucleus and the indices for its deformity (long axis/short axis and circularity index defined as deviation from the perfect circle) were measured on pontine sections and their relation to NIs was statistically analyzed. Cross-sectional area of neuronal nuclei harboring ubiquitin-immunopositive NIs was significantly larger (110.6+/-1.6 micro m(2), mean +/- SE), while that of nuclei not harboring NIs was smaller (77.8+/-1.5 micro m(2)) than that in controls (90.5+/-0.7 micro m(2)). This difference remained significant even when the cross-sectional area occupied by NIs was subtracted from that of the nucleus harboring the NI (97.4+/-1.5 micro m(2)). This could hardly be explained if nuclear shrinkage is accelerated in the presence of NI. On the contrary, NI formation in pontine neurons of NIID might be linked, either directly or indirectly, to a mechanism, which counteracts rather than accelerates nuclear shrinkage. Because nuclear deformity was apparent even in neurons with NIs, whose nuclei were significantly larger than controls, the nuclear deformity is not secondary to its shrinkage and represents another aspect of neurodegeneration independent of nuclear shrinkage. Association of NIs to neurons of larger nuclear size in NIID brain indicates that NIs are not necessarily toxic to neurons.

Adult↗

Expression of nitric oxide synthases in the anterior horn cells of amyotrophic lateral sclerosis.

The authors investigated for a correlation between the expression of nitric oxide synthases (NOSs) with the severity of motor neuronal loss in the anterior horns of patients with amyotrophic lateral sclerosis (ALS). Spinal cords from six patients with ALS and from three normal controls were examined. The sections of cervical, lumbar, and sacral cord including Onuf's nucleus, which are seldom degenerated until the late stage, were stained with three antibodies against NOSs (anti-n-NOS, anti-e-NOS, and anti-i-NOS) using ABC methods. Perikarya of motor neurons in ALS, but not in controls, were immunoreactive against anti-n-NOS and e-NOS. Anti-i-NOS did not recognize the motor neurons of ALS or of controls. The immunoreactivity for n- and e-NOSs was approximately the same in the sections of cervical, lumbar, and sacral cord in ALS. No significant differences in immunoreactivity were observed among the patients with ALS. These results suggest that the expression of NOSs does not immediately affect neuronal loss in ALS.

Adult↗