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Biomedical subjects

M Niimi

Publications and source records attributed to M Niimi.

At least 181 records · Page 10Linked to original sources
PubMed1982

A cerebellar ataxic rat produced by kainic acid and changes in concentration and turnover rates of catecholamines in discrete brain regions.

We made an animal model of cerebellar ataxia by injections of kainic acid into the cerebellar hemispheres on both sides of male rats. The histological and behavioral changes were observed at 4 weeks following the injections. The concentrations of catecholamines and the disappearance rates of alpha-MPT-induced catecholamines were measured in discrete regions of the brain of sham-operated and kainic acid-lesioned rats. A lowered dopamine disappearance rate was seen in the accumbens nucleus of the lesioned rats, but no change in norepinephrine. These findings suggest that the decrease in dopamine turnover in the accumbens nucleus is involved in the development of ataxic behavior.

Animals↗
PubMed1980

Changes in cyclic nucleotide levels and dimorphic transition in Candida albicans.

The relationship between the levels of cyclic nucleotides and dimorphic transition in Candida albicans was examined. The results showed that cells of this pathogenic fungus contained both cyclic adenosine 3',5'-monophosphate (cAMP) and cyclic guanosine 3',5'-monophosphate (cGMP), the concentration of the latter being about one-tenth that of the former in stationary-phase cells of the yeast form. Our results further indicated that germ tube formation induced by incubation at 40 degrees C followed a rise in cAMP concentration in the cell with no accompanying change in cGMP content. Cysteine, which suppressed germination, also reversed the increase in intracellular cAMP concentration. Dibutyryl cAMP (1 MM) significantly promoted germination in proline medium at temperatures of 32 to 34 degrees C. These results suggested that cAMP was one of the controlling factors in the morphological transition in Candida albicans.

Bucladesine↗
PubMed1978

Thalamic afferents to the limbic cortex in the cat studied with the method of retrograde axonal transport of horseradish peroxidase.

Thalamic afferents to the limbic cortex in the cat were studied with the method of retrograde axonal transport of horseradish peroxidase. The anterior limbic region receives fibers largely from the anteromedial nucleus and partly from the anterodorsal and anteroventral nuclei. There appears to be a dorsoventral organization of cortical projections of the anteromedial nucleus to the anterior limbic region. The cingular area has its main input from the anteroventral and anteromedial nuclei. The lower bank and fundus of the splenial sulcus receive fibers from the anteroventral nucleus, particularly its parvocellular part. The retrosplenial area receives projections from the naterodorsal, anteroventral and anteromedial nuclei. The agranular retrosplenial area (area 30) recieves hardly any fibers from the anterior thalamic nuclei. The postsubicular and presubicular areas receive cortical afferents from the anterodorsal, anteroventral (both magnocellular and parvocellular parts) and anteromedial nuclei. In addition, the limbic cortex receives many fibers from the dorsal lateral, medial pulvinar and lateral pulvinar nuclei, and few fibers from the intralaminar and midline nuclei.

Afferent Pathways↗
PubMed1978

Cortical projections of the anterior thalamic nuclei in the cat.

Unilateral stereotaxic lesions were made in the anterior thalamic nuclei of the cat, and the ensuing terminal degeneration traced to the medial cortex by the methods of Nauta-Gygax and Fink-Heimer. The anterodorsal nucleus projects to the retrosplenial, postsubicular and presubicular areas. These projections appear to be organized in the dorsoventral direction. The posterior portion of the retrosplenial area receives no fibers from the anterodorsal nucleus. Fibers from this nucleus are distributed largely in layer I and in layer III and the deep portion of layer II of the posterior limbic cortex. The anteroventral nucleus sends fibers to the cingular area and parts of the retrosplenial, postsubicular and presubicular areas. These projections appear to be organized in a topical manner mediolaterally. When the lesion involves the parvocellular part of the nucleus, degeneration spreads to the lower lip, bank and fundus of the splenial sulcus. There appears to be an anteroposterior organization in the cortical projections of the anteroventral nucleus. Fibers from the anteroventral nucleus are distributed most profusely in layers IV and III and in the superficial portion of layer I of the posterior limbic cortex. The anteromedial nucleus sends fine fibers to the anterior limbic region and to the cingular, retrosplenial, postsubicular and presubicular areas. The cortical projections of the anteromedial nucleus appear to be topographically organized in the dorsoventral direction. Fibers from the anteromedial nucleus are distributed largely in cortical layers V and VI of the anterior and posterior limbic regions.

Animals↗
PubMedDate not supplied

Corticotropin-releasing factor (CRF)-like immunoreactivity in the adrenal medulla.

Bovine adrenal medulla extract prepared by acid-acetone or acid methanol extraction showed two peaks of CRF-like immunoreactivity on Sephadex G-50 chromatography. One eluted near the void volume and another (low molecular weight CRF-like immunoreactivity) eluted slightly before arginine vasopressin (AVP), while most of the immunoreactivity in bovine hypothalamus coeluted with synthetic ovine CRF. When low molecular weight CRF fractions were chromatographed by reversed phase high performance liquid chromatography, three CRF-like immunoreactive peaks appeared. The first peak appeared near TRH, the second one eluted near AVP and the last one eluted near somatostatin. These three peaks of immunoreactivity showed ACTH releasing bioactivity in rat pituitary cells cultures. Therefore, the adrenal medulla-CRF-like substances might be tissue-CRF which may play a role to stimulate ACTH release in the severe stress conditions.

Adrenal Medulla↗
PubMedDate not supplied

Immunohistochemical identification of corticotropin releasing factor-containing neurons projecting to the stalk-median eminence of the rat.

The site of origin of CRF-containing projections to the rat median eminence was studied with immunofluorescence for CRF in combination with the retrograde transport of True blue. After the injection of True blue into the median eminence, retrogradely-labeled CRF producing neurons were identified in the medial division of the paraventricular nucleus and the periventricular nucleus. CRF neurons in the preoptic region had no positive dye. The present findings demonstrate that CRF neurons in the paraventricular and periventricular nuclei project directly to the median eminence.

Animals↗