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Biomedical subjects

M Ozeki

Publications and source records attributed to M Ozeki.

141 records · Page 8Linked to original sources
PubMed1967

Crayfish muscle fiber: ionic requirements for depolarizing synaptic electrogenesis.

Presence of sodium in the bathing medium is not essential for the electrically excitable depolarizing electrogenesis of crayfish muscle fibers, production of action potentials being dependent on calcium. The depolarizing electrogenesis of the excitatory synaptic membrane component does require sodium, however, and this ion cannot be replaced by lithium as it can in spike electrogenesis of many cells. Ionophoretic applications of glutamate, which in the presence of sodium depolarize the cell by activating the excitatory synaptic membrane, are without effect in the absence of sodium. Not only is there no depolarization, but the membrane conductance also remains unchanged. Thus, in the absence of inward movement of sodium across the synaptic membrane there is also no outward movement of potassium. Accordingly, it seems that increased conductance for potassium is not an independent process in the synaptic membrane, whereas it is independent of sodium activation in spike electrogenesis. Chloride activation is independent, however; increase in conductance and the electrogenesis of the inhibitory synaptic component are not affected by the absence of sodium. Implications of these findings regarding the structure of differently excitable membrane components are discussed.

Animals↗
PubMedDate not supplied

Intensification of the 5.9-nm actin layer line in contracting muscle.

According to the cross-bridge model of muscle contraction, an interaction of myosin heads with interdigitating actin filaments produces tension. Although X-ray equatorial diffraction patterns of active (contracting) muscle show that the heads are in the vicinity of the actin filaments, structural proof of actual attachment of heads to actin during contraction has been elusive. We show here that during contraction of frog skeletal muscle, the 5.9-nm layer line arising from the genetic helix of actin is intensified by as much as 56% of the change which occurs when muscle enters rigor, using a two-dimensional X-ray detector. This provides strong structural evidence that myosin heads do in fact attach during contraction.

Actins↗
PubMedDate not supplied

An autopsy case with clinically and molecular genetically diagnosed Huntington's disease with only minimal non-specific neuropathological findings.

An autopsy case with clinically and molecular genetically diagnosed Huntington's disease (HD) accompanied with minimal non-specific neuropathological features was reported. When the patient was 45 years old, he had faulty memory, mood swing, personality change and agitation. Neurological and psychiatric examinations revealed choreoathetoid movements in limbs and trunk, generalized hyperreflexia and mental deterioration. However, cerebellar ataxia and muscle rigidity were not disclosed. Neuroimaging study did not show a definite atrophy of heads of caudate nuclei. Neuroacanthocytosis and Wilson's disease were ruled out by the peripheral blood examination and serum Cu and ceruloplasmin examination. At the age of 55 he died of pneumonia. Post-mortem examination revealed minimal non-specific neuropathological features for HD (Vonsattel's grade 0), that is, no visible fibrillary gliosis in the striatum, and few neuronal loss and only proliferation of astrocytes (astrocytosis) in the striatum. Molecular-genetic study the patient's brain tissues and his youngest son's blood was performed. These studies revealed 40 CAG repeats in the patient, 56 CAG repeats in his youngest son. These results suggest they may be HD. Vonsattel et al. [ 1998] insist that grade 0 comprises 1% of all HD brains, and grade 1 comprises 4% of all HD brains. But we could not find any reports in which the clinical and neuropathological features were described in detail on the cases with clinically and molecular genetically diagnosed HD without specific pathological findings. Therefore, we present in detail the clinical and neuropathological features of such case.

Brain↗
PubMedDate not supplied

Correction of tetralogy of Fallot accompanied by malignant hyperthermia. Case report.

A 5-year-old girl susceptible to malignant hyperthermia underwent total repair of tetralogy of Fallot. The initial operation was canceled because of abrupt hyperthermia and metabolic acidosis of unknown cause. Dantrolene was given orally as preoperative treatment and administered intermittently during surgery. Postoperative hyperthermic crisis was successfully treated with intravenous dantrolene combined with surface cooling, gastric tube irrigation with cold saline, and alcohol vaporization.

Child, Preschool↗
PubMedDate not supplied

Successful surgical treatment of subaortic stenosis caused by an accessory mitral valve.

A 22-month-old boy with subaortic stenosis was found to have relatively mature mitral valve tissue beneath the aortic valve, associated with a hypertrophic and prominent interventricular septum. This tissue caused obstruction of the left ventricular outflow tract and resulted in a pressure gradient of 70 mmHg between the aorta and the left ventricle. Surgical treatment was successfully performed to excise the tissue and part of the hypertrophic ventricular septum. Results of microscopic examination of the resected specimen are shown and discussed.

Aortic Valve Stenosis↗