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Biomedical subjects

K Niijima

Publications and source records attributed to K Niijima.

At least 55 records · Page 3Linked to original sources
PubMed1990

Marked decrease of mitochondrial DNA with multiple deletions in a patient with familial mitochondrial myopathy.

Muscle mitochondrial DNA (mtDNA) from a patient with mitochondrial myopathy was examined by Southern blotting. Her family history suggests autosomal dominant inheritance of this disorder. In contrast to other cases of this myopathy that are associated with a compensatory increase of mitochondria, in this patient, the content of mtDNA was markedly decreased (15% of controls), whereas protein of the ATP synthase beta-subunit was not decreased appreciably as judged by Western blotting. In addition, the mitochondrial DNA had multiple deletions, which were located between the replication origins of the heavy strand and light strand.

Adult↗
PubMed1990

Interleukin 3 as a trophic factor for central cholinergic neurons in vitro and in vivo.

We have found that interleukin 3 (IL-3), a growth factor for hematopoietic cells, is a novel trophic factor for mouse and rat central cholinergic neurons. It enhanced neurite outgrowth and elevated choline acetyltransferase activity. The effect seems to be specific for cholinergic neurons, since somatostatin release and glutamic acid decarboxylase and 2',3'-cyclic nucleotide 3'-phosphodiesterase activities were not significantly influenced by IL-3. In vivo, IL-3 was infused into the lateral ventricles of rats after unilateral axotomy of the septohippocampal pathways. Two weeks later, the IL-3-treated animals showed significant numbers of acetylcholinesterase-positive neurons remaining in the septal region.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1990

[A new family of Machado-Joseph disease--an abnormal decrease in signal intensity of the putamen in magnetic resonance imaging].

The propositus (case 1) was a 40 year-old man. He had begun to note unsteady walking at age 26. He was found to have cerebellar ataxia and pyramidal signs in addition to minor features such as progressive external ophthalmoplegia, gaze nystagmus, bulging eyes, intention fasciculation-like movements of facial and lingual muscles, and limb dystonia. These findings were categorized into type II form of the disease. One sister (case 3) aged 37 years, and one brother (case 4) aged 44 years of the propositus had also type II form of the disease. His uncle (case 2) had the same cerebellar and extrapyramidal signs accompanied with peripheral nerve signs such as muscle wasting, weakness, hypo-tonus and decreased deep tendon reflexes, and a diagnosis of type III form of the disease was made. In the T2-weighted magnetic resonance imaging (1.5 T, TR 2000 or 3000 msec, TE 120 msec) of the three patients (case 1, 3 and 4), dorsolateral part of the putamen showed decreased signal intensity. Although hypo-intensity of the putamen is often observed in normal elderly people over 50 years old, it is considered to be abnormal when it exists in relatively young people as in this family members.

Adult↗
PubMed1989

Impairment of active avoidance produced after destruction of pedunculopontine nucleus areas in the rat.

Pedunculopontine nucleus areas were lesioned bilaterally in the rat by local injection of kainic acid. When rats so treated were tested for active avoidance behavior in shuttle boxes we found that their avoidance acquisition was completely abolished, whereas their intertrial locomotor activity and escape behavior were not affected. In the lesioned rats, choline acetyltransferase activity in the medial thalamus and substantia nigra decreased, but not in the lateral thalamus, hippocampus, or cerebral cortex. These findings suggest that the cholinergic pedunculopontine-medial thalamus projection plays an important role in memory acquisition in the rat.

Animals↗
PubMed1988

Activation of mesencephalic dopamine neurons by chemical stimulation of the nucleus tegmenti pedunculopontinus pars compacta.

Unilateral stereotaxic microinjection of a small amount of kainic acid (KA) into the nucleus tegmenti pedunculopontinus pars compacta (TPC) of male Wistar rats produced constant ipsiversive circling behavior. The rate of the TPC-derived circling was significantly attenuated by blocking agents of dopamine systems, including haloperidol and alpha-methyl-tyrosine (both injected intraperitoneally) and also 6-hydroxydopamine (injected into the bilateral medial forebrain bundles). Administration of norepinephrine antagonists (phenoxybenzamine hydrochloride and DL-propranolol) had no effect on the rate of the TPC-derived circling. Bilateral preinjections of atropine sulfate into the ventral midbrain tegmentum, including the ventral tegmental area and the pars compacta of the substantia nigra, significantly attenuated the rate of the circling. The unilateral KA injection into the TPC dramatically increased the ratio of HVA + DOPAC/dopamine, an indicator of dopamine turnover, in the nucleus accumbens as well as in the striatum bilaterally. The increase of the ratio in the nucleus accumbens was selectively suppressed by pretreatment with atropine sulfate administered into the bilateral ventral midbrain tegmentum. These facts indicate: (1) the TPC-derived circling behavior is mediated by the dopamine system, (2) the chemical stimulation of TPC by KA might produce an activation of midbrain dopamine neurons by excitatory TPC efferents to the dopamine neurons and enhance the dopamine turnover in the nucleus accumbens as well as in the striatum, (3) the excitatory TPC efferents may be muscarinic cholinergic in accordance with previous reports.

Animals↗
PubMed1987

Long-term effect of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on striatal dopamine content in young and mature mice.

Long-term effects of MPTP on striatal dopamine (DA) content and the influence of aging on the recovery were investigated in mice. Male C57BL/6J mice, young (2-month-old) and mature (10-month-old), were used. Two different dosage schedules of MPTP, i.e., 4 doses subcutaneous injections of 20 mg/kg each, and 4 doses subcutaneous injections of 40 mg/kg each, were given to both young and mature mice at 12-h intervals. Assays of striatal DA and 3,4-dihydroxyphenylacetic acid (DOPAC) content were performed 1 week, 1 month, 2 months, and 3 months after the last injection of MPTP. MPTP produced a marked reduction (-75% to -80%) of striatal DA content in both young and mature mice 1 week after the last injection of MPTP. In young mice, the striatal DA content showed a partial recovery in the subsequent stages studied. In contrast, no apparent recovery occurred in mature mice until as long as 3 months after the last injection. The results suggest that mice have a capacity for partial recovery of the striatal DA contents which was depleted by MPTP, and this capacity for recovery appears to be impaired in mature mice.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1987

Neurophysiological analysis of ataxia in capsular ataxic hemiparesis.

A quantitative analysis of ataxia and the readiness potential were studied in four cases of ataxic hemiparesis resulting from a small infarct in the posterior limb of the internal capsule. The ataxia appeared to be the result of involvement of the corticopontine tract originating from the precentral region (areas 4 and 6) at this level. The voluntary movements of the affected limbs were characterized by slowness and irregularity similar to those seen in cerebellar ataxia. The weakness per se was not such that it could account for the ataxia. The dentato-rubro-thalamo-cortical system did not appear to be significantly involved on the basis of normal readiness potentials.

Ataxia↗
PubMed1986

Changes in gamma-aminobutyrate, glutamate, aspartate, glycine, and taurine contents in the striatum after unilateral nigrostriatal lesions in rats.

Contents of five amino acids (gamma-aminobutyrate (GABA), glutamate, aspartate, glycine, and taurine) were assayed in the rat striatum in which nigrostriatal pathways were unilaterally destroyed by 6-hydroxydopamine. GABA content in the operated side was significantly increased 1 month after the surgery compared with that in the nonoperated side. Contents of four other amino acids assayed did not change significantly. Among possible mechanisms for this elevation we postulated that sprouting of the GABAergic terminals in the striatum would be most probable.

Amino Acids↗
PubMed1985

[Electrophysiological identification of neurons of the substantia innominata].

Recently in senile dementia of Alzheimer type, neuronal loss of cholinergic neurons in the substantia innominata is described. However these findings are based on morphological studies and, so far, these neurons have not been identified physiologically. In this study we tried to record these neurons electrophysiologically by antidromic activation. Cats were anesthetized with sodium pentobarbital and paralyzed with gallamine triethiodide. Three arreys of 3 or 4 silver-ball stimulating electrodes were fixed to the surface of the cerebral cortex. Each electrode was stimulated by rectangular pulses of 1 msec duration. Recording electrodes were glass micropipettes filled with 2 M NaCl saturated with fast green FCF and inserted into the ipsilateral substantia innominata stereotaxically. Twenty-eight neurons were constituted of mainly negative component; suggesting that they were recorded from cell bodies, not from axons. Also they responded in an all-or-none manner and showed constant latencies when stimulus intensities were at threshold level. When paired stimuli were applied, the latency of the action potential to the second stimulus was equal to that of the first one. These neurons were, therefore, considered to be activated antidromically. These neurons had axons of very slow conduction velocities. They are divided into two groups according to conduction velocities. The first group had mean conduction velocity of 2.3 m/sec and they responded to rather high frequency stimuli. The second group had mean conduction velocity of 1.0 m/sec and neurons belonging to this group showed quite long refractory periods. Based on conduction velocity analysis, the former is thought to include neurons with myelinated axons and the latter those with unmyelinated ones.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Choriocarcinoma arising from the pituitary fossa with extracranial metastasis: a review of the literature.

Since Askanazy's first report on a case of primary intracranial choriocarcinoma in 1906, more than 60 cases have been reported so far. We add to that a case of intrasellar choriocarcinoma with suprasellar extension: A 12-year-old girl showed cranial nerve palsies, hypopituitarism, and abnormally high titers of human chorionic gonadotropin (HCG) in blood and in cerebrospinal fluid (CSF). She died 3 months after surgery. At autopsy, an intra- and suprasellar choriocarcinoma, which penetrated through the clivus into the cerebellopontine angle and metastasized remotely to the lungs, was confirmed. This rare case is presented with a thorough review of the literature.

Adolescent↗