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Biomedical subjects

R Tanaka

Publications and source records attributed to R Tanaka.

At least 919 records · Page 51Linked to original sources
PubMed1976

Unusual intranuclear filaments in the circulating lymphocytes of patients with multiple sclerosis and optic neuritis.

Mononuclear cells obtained from the peripheral blood of patients with multiple sclerosis (MS) and optic neuritis (ON) were examined by electron microscopy. Unusual intranuclear filaments identical with the so-called paramyxovirus-like filaments were found in circulating lymphocytes from 5 patients with MS and 3 with ON. They were observed in 0.1 to 0.5% of the mononuclear cells. Electron microscopy of the blood cells from 5 other patients with ON, 3 patients with neurologic diseases other than MS, and 4 normal subjects failed to reveal similar structures. The filaments were also absent from blood cells from blood cells from normal subjects during the process of autolysis.

Adolescent↗
PubMed1975

The vestibulospinal tract: crossed and uncrossed effects on hindlimb motoneurones in the cat.

Effects produced by stimulation of Deiters' nucleus on contralateral hindlimb motoneurones were investigated in the cat with intracellular and monosynaptic reflex recording. Polysynaptic PSPs were evoked in all species of motoneurone examined. The minimal synaptic linkage was found to be disynaptic in the excitatory path and prisynaptic in the inhibitory path. Experiments with various lesions to the spinal funiculus and those with mapping of the stimulated sites in the brain stem showed that the effects were evoked almost exclusively via the lateral vestibulospinal tract of the stimulated side. The crossed effects were excitatory in extensor motoneurones of all species studied except for hip extensors (ABSm) in which EPSPs and/or IPSPs were evoked. The effects on flexors, by contrast, were not simple and consisted of EPSPs, IPSPs or a mixture of both. The difference in effects depended, though not entirely, on the species of motor nucleus. Between the excitatory and inhibitory effects on knee flexor (PBSt) motoneurones the former predominated under chloralose and the latter under pentobarbital anaesthesia. By recording PSPs evoked from the two vestibulospinal tracts in the same motoneurone, the convergence pattern and the magnitude of effects from the two tracts were studied. The interneuronal organization of the crossed vestibulo-motoneuronel pathway and its functional significance are discussed.

Animals↗
PubMed1975

Paramyxovirus-like structures in brains of multiple sclerosis patients.

Twenty-four plaques obtained at autopsy from the brains of six patients with multiple sclerosis were examined under an electron microscope. Specimens for ultrastructural study were processed from the unfixed brain tissues at the time of autopsies. Intranuclear filaments with a diameter of 150 to 260 Angstroms of possibly two different types were seen in the macrophages and in unidentified mononuclear cells that were infiltrating the perivascular regions of four plaque areas from three patients. Intracytoplasmic reticular filaments with a diameter of 100 to 130 A were seen in the astrocytes and in unidentified cell processes in five plaques from three cases. A possible link between these intranuclear filaments and paramyxovirus is suggested.

Astrocytes↗
PubMed1975

Acute SSPE.

Two patients had acute fulminanting encephalitis and the typical pathological changes of subacute slcerosing panencephalitis (SSPE). It is suggested that SSPE should be considered in the differential diagnosis of acute viral encephalitis.

Adolescent↗
PubMed1975

The mode of activation of pyramidal tract cells by intracortical stimuli.

1. Direct and indirect effects of intracortical stimulattion on pyramidal tract cells were compared in the monkey and in the cat under barbiturate or chloralose anaesthesia. The hind-limb motor areas were explored, that in the monkey only within the convex part of the precentral gyrus. The intracortical stimuli were applied in the nearest vicinity of pyramidal tract cells, where antidromic spike potentials of single cells were recorded. 2. Average records of descending volleys in corticospinal tract fibres were taken from the surface of the lateral funiculus or from its dissected fascicles. The sensitivity of the recording was sufficient to detect responses in single fibres. 3. The latencies of the earliest descending volleys evoked by weak intracortical stimuli were compared with the latencies of the antidromic spike potentials of pyramidal tract cells evoked by stimulation of the lateral funiculus at a low lumbar level (same conduction distance). Only in about one third of cases these latencies were similar and compatible with a direct activation of pyramidal tract cells. In the remaining cases they indicated mono- or polysynaptic activation of pyramidal tract cells. 4. Latencies of the later components of the descending volleys indicated that they were due to indirect activation of pyramidal tract cells in practically all cases. 5. The components of the descending volleys attributable to the indirect activation of pyramidal tract cells were greatly increased when repetitive intracortical stimuli were applied instead of single ones. 6. The investigation leads to the conclusion that a weak intracortical stimulation is relatively ineffective in a direct excitation of pyramidal tract cells and that the effects of such a stimulation are mainly indirect, especially when repetitive stimuli are used.

Animals↗
PubMed1975

Projections of pyramidal tract cells to alpha-motoneurones innervating hind-limb muscles in the monkey.

1. We have investigated the spatial organization of monosynaptic corticospinal projections to hind-limb motoneurones, using near threshold stimulation of the surface of the precentral gyrus to activate pyramidal tract (PT) cells and intracellular recording from motoneurones to detect the resulting e.p.s.p.s. 2. Monosynaptic e.p.s.p.s. of cortical origin were seen in all motoneurone species investigated, those of distal as well as of proximal hind-limb muscles. The proportion of motoneurones in which the e.s.p.s. were evoked and the amplitudes of the latter indicated a more extensive cortical projection to motor nuclei for distal than for proximal muscles, as previously found for forelimb motoneurones. 3. Cortical areas from which monosynaptic e.p.s.p.s. were evoked in individual motoneurones were remarkably large, most often between 3 and 7 mm2. Several motoneurones appeared to have two or three separate areas within the hind-limb division of the motor cortex. 4. Areas of location of pyramidal tract cells projecting to various motoneurones innervating one muscle were usually not identical. They overlapped often only partially or did not overlap at all. 5. Areas of location of pyramidal tract cells projecting to motor nuclei for different muscles often showed an extensive overlap. When it occurred, various motoneurones of a given motor nucleus had common cortical projection areas with motoneurones of other motor nuclei, either to synergistic or to antagonistic muscles. Our results give further evidence for overlapping of areas of cortical projections to motoneurones and speak against a mosaic-like organization of pyramidal tract cells projecting to different motor nuclei. 6. The rise times of cortically evoked e.p.s.p.s. indicate that the corticospinal tract fibres terminate on motoneurones at approximately similar distances from the soma as group Ia afferents. The small amplitudes of the majority of e.p.s.p.s. evoked by near threshold cortical stimulation therefore suggest that unitary e.p.s.p.s of cortical origin are small and that the density of pyramidal tract cells projecting to individual motoneurones is usually low, even in the centrum of projection areas. 7. Effects of intracortical stimulation depended on the stimulus strength. With currents of 2-3 muA, e.p.s.p.s were usually evoked in one motoneurone species or in close synergists. With currents of 5-10 muA, largest e.p.s.p.s a number of other motoneurones. Latencies of descending volleys in the lumbar corticospinal tract indicated that intracortical stimuli activated pyramidal tract cells indirectly; the effects of these stimuli could thus not be used to indicate the location of pyramidal tract cells responsible for them.

Animals↗
PubMed1975

Effect of an exposure to chloramine-T on the immunoreactivity of glucagon.

Various preparations of glucagon treated with chloramine-T under different conditions have been studied with respect to their immunoreactivity toward two different glucagon antisera; one specific for pancreatic glucagon and the other capable of reacting with enteroglucagon as well. The glucagon preparations exposed to chloramine-T for different periods reacted almost identically with the nonspecific antibody whether they were used as tracer or standard. On the contrary, treatment with chloramine-T under severe conditions led to reduced immunoreactivity toward the specific antibody. Inclusion of dimethyl sulfoxide (DMSO) in the chloramine-T reaction resulted in preservation of the immunoreactivity of the treated preparations. The cyanogen bromide cleaved-glucagon, (1-26) homoserine lactone, showed little cross-reactivity with the specific antibody whereas it reacted to a similar extent with the nonspecific antibody as natural glucagon did. Amino acid analysis of the hormone exposed to chloramine-T demonstrated that the methionine residue at position 27 in the glucagon molecule had been oxidized to methionine sulfoxide. In addition, tryptophan had also been affected. DMSO protected methionine and tryptophan from the oxidative action of chloramine-T. We postulate from these results that the change in the immunoreactivity toward the specific antibody of glucagon exposed to chloramine-T is mainly due to oxidation of the methionine residue at position 27 in the molecule. The usefulness of DMSO in the iodination process is also discussed.

Animals↗
PubMed1975

Boiling method for the extraction of gut glucagon-like immunoreactive materials.

The boiling method deviced in accordance with the extraction procedure of secretin was applied to the extraction of gut glucagon-like immunoreactive material (GLI) and compared with the acid alcohol method of Kenny with respect to efficiency of the extraction and property of the extracted materials. GLI was extracted from minced porcine small intestine by each method. The total amount of GLI extracted by the boiling method was 14.45+/-2.07 mug/10g small intestine (mean+/-SE), showing a high yield as compared to 4.07+/-0.29 mug/10 g small intestine obtained by the acid alcohol method. The difference was statistically significant (p less than 0.005). The gel chromatogram of the acid alcohol extract was separated into two peaks; peak 1 appeared before the the insulin marker, while peak II was eluted with the glucagon marker. The chromatogram of the boiling extract has a main broad fraction including insulin marker and a minor second peak corresponding to peak II of the acid alcohol extract. Boiling of the acid alcohol extract did not cause any shift of peak I in chromatogram. GLI present in the first half of the main fraction of the boiling extract was different from that in the latter half, but identical to peak I of the acid alcohol extract with respect to the immunoreactivity against glucagon antibody. It is concluded that in the extraction of GLI not only high yield is achieved but one or more new components is picked up by the boiling procedure as compared to the acid alcohol method.

Animals↗
PubMed1975

QT prolongation and syncopal attacks. A case of the Romano-Ward syndrome.

The Romano-Ward syndrome is very rare as hereditary disease. Only 5 families have been reported in Japan before the present report. The patient, a 15-year-old female, had been treated for epilepsy due to syncopal attacks. Electrocardiography revealed occurrence of an augmented and labile U wave and prolongation of the Q-T interval, with recordings of frequent multifocal extrasystoles and transient ventricular fibrillation. Also noticed was sinus bradycardia. Clinical examinations presented no results coinciding with those specific ECG findings. It was inferred through surveys of her family tree that the present case had an autosomal dominant trait, heterozygously affected through the male line. Severe arrhythmias detected on her ECGs were suppressed by oral administration of 30 mg/day propranolol. Judging from the fact, propranolol may be the first to be administered among a variety of anti-arrhythmic agents in the Romano-Ward syndrome.

Adolescent↗