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Biomedical subjects

N Murakami

Publications and source records attributed to N Murakami.

At least 631 records · Page 35Linked to original sources
PubMed1979

Studies on the nuclear binding of steroid hormone-receptor complex; characteristics of binding of nuclei from fetal rat liver to 3H-dexamethasone-liver cytoplasmic receptor complex.

Binding of 3H-dexamethasone (Dex)-rat liver cytoplasmic receptor complex to nuclei from fetal rat livers in vitro exhibited a high-affinity and saturable nature (Kd=1.5 X 10- M, maximal binding sites=470 fmole/mg DNA), and the binding was inhibited competitively by prior injection of Dex in vivo. While binding of 3H-Dex-receptor complex to nuclei from adult rat liver was in low affinity and unsaturable, and injection of Dex prior to the sacrifice of animals did not influence the nuclear binding to 3H-Dex-receptor complex in vitro. Differential salt-extraction with KCl solution of the nuclear bound 3H-Dex receptor complex revealed the presence of salt-extractable and residual forms of bound receptors. The amount of the fraction extracted with 0.3 M KCl reached its maximum at 10 min after the start of incubation, while the 1.0 M KCl-extractable and residual fractions reached their maximum plateaus after 30 min of the incubation. Scatchard analysis revealed that the binding of the receptor complex to the 0.3M and 1.0M KCl fractions was saturable, while the residual fraction did not show any tendency of saturation under the experimental conditions employed in the present study. The results obtained in this work were compared to those which have been reported by other investigators.

Animals↗
PubMed1979

Studies on the nuclear binding of steroid hormone-receptor complex; binding of liver and thymus dexamethasone-receptor complex and prostate dihydrotestosterone-receptor complex to nuclei from various tissues.

To examine the binding specificity of steroid hormone-cytoplasmic receptor complexes to nuclei, binding of 3H-dexamethasone (Dex)-liver, 3H-Dex-thymus and 3H-dihydrotestosterone (DHT)-prostate receptor complexes to nuclei from liver, prostate, thymus, spleen and kidney was studied. It was observed that a significant amount of steroid-receptor complexes was bound to any nuclei used in the present study and the extent of the binding of receptor complexes to nuclei from homologous tissues was not always greater than that to nuclei from heterogenous tissues. However, a significant portion of the 3H-Dex-liver and 3H-DHT-prostate receptor complexes was not absorbed by nuclei from kidney, spleem, and thymus, and the unabsorbed complexes were efficiently bound to liver and prostate nuclei. The results obtained indicate that two types of receptor complex with regard to nuclear binding were present in cytosols of liver and prostate; one binds to nuclei from kidney, spleen, thymus, liver and prostate and the other does not bind to nuclei from kidney, spleen and thymus but does bind to nuclei of liver and prostate. The latter type of receptor complex was not observed in the cytosol from the thymus.

Animals↗
PubMed1978

Cervical myelopathy due to ossification of the posterior longitudinal ligament: a clinicopathologic study.

A clinicopathologic study was done of a Japanese patient with symptomatic ossification of the posterior longitudinal ligament in the cervical spine. Post-mortem specimen showed characteristic distribution of degenerations at C5-6 segments similar to chronic cervical spondylosis or disk protrusion. The degenerative changes were confined to the ventral two thirds of the posterior and lateral columns. In addition to demyelination, loss of axons, and neuronal cell death, thickening of venular wall and fine capillary neovascularization strongly suggested chronic circulatory insufficiency. Spinal immobilization produced by the ossified ligament may have contributed to the long clinical course, lasting for 30 years. Review of literature showed that the myelopathy can be distinguished clinically and radiographically from that produced by cervical spondylosis.

Aged↗
PubMed1978

Cytogenetic and dominant lethal studies on captan.

Possible mutagenic activity of captan was investigated by in vitro and in vivo cytogenetic studies and by the dominant lethal study in mice. In vitro cytogenetic study with cultured human diploid cells revealed a significant increase in the frequency of cells showing stickiness and a severe mitotic inhibition at concentrations of 3.0 and 4.0 microgram of captan per ml. although no chromosomal aberrations were observed. In in vivo cytogenetic study, no chromosomal aberrations were induced in the bone marrow cells of rats treated orally with captan at a single dose of 500, 1000 or 2000 mg/kg or at five consecutive doses of 200, 400 or 800 mg/kg/day. Dominant lethal study also failed to show any mutation induction after treatment of male mice with daily oral dose of 200 or 600 mg of captan per kg bw for five days.

Animals↗
PubMed1978

Conditions for establishment of reflex ovulation in light estrous rats.

Continual anovulatory state associating with persistent vaginal cornification (light estrus) was induced by placing 4-day cycling rats under continuous lighting (LL). Uterine cervical stimulation was applied at arbitrary solar hours to light estrous rats showing continual vaginal estrus for more than 2 weeks. The ovulation was induced between 14 and 16 hr after the stimulation dissociating entirely with solar hours. Injection of anti-LHRH serum 5 min after the stimulation but not later than 20 min blocked this ovulation. Ovulation thus induced was always followed by pseudopregnancy with continual leucocytic vaginal smear lasting 10.70 days. The change in concentrations of peripheral serum progesterone during this period was almost similar to that of normal pseudopregnancy except extremely low levels observed at the start and end. Effectiveness of the cervical stimulation for induction of ovulation in light estrous rats was related to not only the duration of light estrus but also the time after transfer to LL, suggesting that the neural mechanism of ovulation in light estrous rats shifted from that of the spontaneous to reflex ovulators due to the extinction of environmental photic cue.

20-alpha-Dihydroprogesterone↗
PubMed1978

Nuclei and DNA-binding form of the steroid receptor complex in the liver and the ventral prostate of rats.

Repeated treatments of the liver cytosol prelabeled with 3H-dexamethasone with DNA-cellulose followed by treatments with purified liver nuclei enabled us to assess the amount of two forms of dexamethasone-receptor complex, one binds only to nuclei and the other binds to DNA and nuclei. The comparable amount of these two forms of the receptor complex was detected in the dexamethasone-labeled liver cytosol, while only one form which binds only to nuclei was found in the liver cytosol labeled with antiglucocorticoid, cortexolone. The significant amount of receptor complex which binds to DNA and nuclei was not present in the cytosol from the ventral prostate preincubated with 3H-dihydrotestosterone.

Animals↗
PubMed1977

Binding of cytoplasmic 5alpha-dihydrotestosterone-receptor complex by nuclei from the ventral prostate, liver, and spleen of rats.

Cytoplasmic 3H-5alpha-dihydrotestosterone-receptor complex of the rat ventral prostate was efficiently taken up by nuclei isolated from the liver, the ventral prostate and the spleen. The amount of the complex bound to liver nuclei was approximately 3 times that to prostate nuclei, and a relatively small amount of the complex was taken up by spleen nuclei under the incubation conditions: 0.16 nM complex (2.0 mg as protein) was used. Binding of the complex to liver nuclei was low-affinity and non-saturable, while in nuclei from the ventral prostate and the spleen, high-affinity and saturable binding was observed. Kd of nuclear binding in the latter two tissues was roughly of the order of 10(-10) M. Castration caused a reduction in the binding of the complex to prostate nuclei and replacement therapy with testosterone propionate completely blocked the effect of castration on the nuclear binding. The affinity of high-affinity binding was not changed significantly after castration. No significant effects of castration and testosterone treatment were observed in the binding of nuclei from the other two tissues examined. The physiological significance of the nuclear binding of hormone-receptor complexes in the action of steroid hormones is discussed.

Animals↗
PubMed1977

Rat adrenal corticosteroidogenesis; effect of ACTH, cycloheximide and sterol carrier protein.

Corticosterone formation was determined in the reconstructed rat adrenal system which consisted of the mitochondria and post-mitochondrial supernatant fraction (PM-fraction) supported by l-malate, and effect of ACTH and cycloheximide in vivo and cycloheximide, Ca++ and sterol carrier protein (SCP) in vitro were examined. Mitochondria isolated from adrenals of rats which received ACTH 15 min before sacrifice showed an elevated corticosterone formation. Cycloheximide administration 15 min prior to ACTH injection completely blocked the effect of ACTH but in vitro addition of this drug to the incubation mixture did not modify the rate of corticosterone production even at higher concentrations. Since the PM-fraction isolated from adrenals of rats received ACTH or cycloheximide or both did not change the mitochondrial capacity for corticosterone formation, factor(s) which influenced by ACTH administration seemed to be localized in mitochondria. The SCP-bound cholesterol was utilized for corticosterone formation more efficiently than the free cholesterol when added to the incubation mixture, and this might be due to, at least in part, higher rate of binding to the mitochondrial inner membrane of the SCP-bound cholesterol.

Adrenal Glands↗
PubMed1976

Unit responses in the medulla oblongata of rabbit to changes in local and cutaneous temperature.

1. In anaesthetized rabbits which were stereotaxically implanted with a thermode following decerebellation, thermal sensitivity of neurones in the medulla oblongata to local temperature changes was examined systematically. The medullary temperature was changed by circulating water at various temperatures through the thermode. 2. Eighty-seven temperature-responsive neurones were found in the medulla, especially in the medullary reticular formation. Out of these eighty-seven, forty-eight neurones were cold-responsive neurones, while the rest were warm-responsive. Both types of neurones included not only neurones with linear or continuous relations between discharge rate and local temperature but also neurones with non-linear or discontinuous thermoresponse curves. 3. In the medulla a few of the temperature-responsive neurones showed a dynamic reaction with static discharge rate changes to changes of local temperature. 4. Seven neurones out of the fifteen respiratory neurones encountered during the exploration had thermal sensitivity to respiratory alteration of the discharge. 5. with thermal stimulation of a limited area of the skin, over 50% of the temperature-responsive neurones recorded in the medulla responded positively or negatively to changes in the skin temperature.

Action Potentials↗
PubMed1976

Effects of noradrenaline injected into the brainstem on reflex vasodilatation in the pinna of rabbits.

Reflex vasodilation in one ear of a rabbit following radiant heating of the opposite ear was observed by measuring the heat loss by a change in the heat flux when either noradrenaline or porcaine hydrochloride was administered locally into various diencephalic or mesencephalic loci in the brain. Hypothalamic cooling resulted in less reflex vasodilatation, while no vasodilatatory effect was observed immediately after an intravenous administration of atropin sulphate (0.5 mg). Five mug of noradrenaline injected intrahypothalamically either eliminated or reduced the development of reflex vasodilatation to the same extent as did an injection of procaine hydrochloride (0.5 mg). On the other hand, the magnitude of the reflex vasodilatation increased markedly with an injection of either procaine hydrochloride (1.5 mg) or noradrenaline (10 mug) into the reticular formation of the midbrain. Increased reflex vasodilatation was also obtained with a localized administration of procaine hydrochloride into the medial forebrain bundle of the hypothalamus. The results suggest that the noradrenaline in the preoptic/anterior hypothalamic (PO/AH) area and the midbrain reticular formation exerted an inhibitory effect on the action of the neural structure in connection with the heat dissipation system.

Animals↗
PubMed1975

Effects of antipyretics on normothermic rabbits.

The effects of antipyretics on the ear skin and rectal temperature (Te and Tre) were investigated in non-febrile rabbits placed in a cold environment or when they were cooled locally in the hypothalamus. Intravenous injections of sulpyrin (25-500 mg/kg) or sodium salicylate (25-100 mg/kg) produced the dose-related increase in Te and slight fall in Tre. Decrease in Te induced by hypothalamic cooling was also reversed by the intravenous injection of antipyretics. Intraventricular injections of sulpyrin and salicylate (0.5-5.0 mg/kg) also caused the vasodilatation of the pinna skin and the fall in Tre. Bilateral microinjections of sulpyrin were made into various areas of the brain stem in order to locate the site of action. The injection sites where the vasodilatatory effect was elicited were the anterior hypothalamus, ventromedial nucleus of hypothalamus and the midbrain reticular formation. The responses elicited from the ventromedial nucleus were usually accompanied by restless and violent struggling. Injection of antipyretics into the mammillary body had no effect on Te. Intrahypothalamic injection of procaine depressed the sulpyrin-induced vasodilatation. These findings suggest that action of antipyretics on the normal body temperature is mediated through anterior hypothalamus and midbrain reticular formation.

Analgesics↗