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Biomedical subjects

N Murakami

Publications and source records attributed to N Murakami.

At least 595 records · Page 33Linked to original sources
PubMed1982

Thermosensitive neurons in slice preparations of rat medulla oblongata.

With extracellular recording, we examined thermosensitive neurons in slices of a possible thermosensitive region in the dorsal medulla oblongata of rats. In addition to temperature insensitive neurons, warm- and cold-sensitive neurons were recorded in vitro. The firing rates of many warm- and cold-sensitive neurons responded transiently to temporal changes in slice temperature with "overshoots" and/or "reverse overshoots." In a steady state, warm-sensitive neurons were similar in thermoresponsiveness to those studied previously in the CNS in vivo. Cold-sensitive neurons were unique in that. Most of them were silent at the normal core temperature of 38 degrees C and fired only below their own threshold temperatures (2-6 degrees C below normal).

Animals↗
PubMed1982

The role of corticosterone in cadmium-induced thymic atrophy in mice.

Serum corticosterone levels were determined at intervals after i.p. injection of 1.8 mg cadmium (Cd)/kg body weight. Thymus weight decreased significantly 3 days after injection. The effect of Cd injection on serum corticosterone levels was almost indistinguishable from that of saline injection. Further, Cd-induced thymic atrophy was observed in adrenalectomized mice as well as in sham-operated ones. These results suggest that corticosteroid effect is not essential for the induction of thymic atrophy by Cd.

Adrenalectomy↗
PubMed1982

Foster mother rat entrains circadian adrenocortical rhythm in blinded pups.

Free-running patterns of blood corticosterone rhythm were examined between the fourth and eighth postnatal week in blinded pups optically enucleated on day 1. When blinded pups were raised by intact natural mothers, the peak time of corticosterone rhythm appeared near the time of light-dark (LD) transition, which was close to that of mothers, and then free-ran. This phase relation between mothers and pups showed that mothers entrained pups' corticosterone rhythm. When blinded pups born of LD (or DL) mothers were raised by DL (or LD) foster mothers, the corticosterone rhythm in blinded pups was close to that of foster mothers at 4 wk of age, indicating that a foster mother plays a predominant role in entraining the pups' rhythm. When blinded pups were raised by blinded mothers whose rhythm was out of phase of the lighting cycle, pups' rhythm was in phase with that of mothers, showing that lighting cycle did not affect the pups' rhythm. These facts indicate that the mother nursing pups acts as the most predominant entrainer of corticosterone rhythm of the blinded pups.

Adrenal Cortex↗
PubMed1982

Circadian adrenocortical rhythm in the adrenalectomized rat with or without autotransplanted adrenal gland.

Circadian rhythm of blood corticosterone in adrenalectomized rats with (AT rat) or without adrenal autotransplants was investigated. Blood samples were obtained individually at 4-hour intervals for a 24-hour period per week for 5-7 consecutive weeks by the tail tip incision method. Corticosterone responses of the autotransplanted adrenal gland to ACTH gradually increased with time after the implantation, and by 5 weeks had attained a level comparable to that of intact rats. Concurrently with this change, circadian adrenocortical rhythms in AT rats became evident and they were able to respond to reversed photoperiodic environment. The effects of constant illumination or food restriction on the corticosterone rhythm in AT rats were indistinguishable from those in intact rats in every respect. A sharp drop and disappearance of circadian periodicity were observed in the blood corticosterone levels by removal of autotransplanted adrenals. In some of the adrenalectomized rats, the daily rhythm of the blood corticosterone levels reappeared 5-7 weeks after surgery owing to the hypertrophy of accessory adrenal glands or regeneration from capsular fragment left in situ. These results suggest that neural input to the adrenal is not essential for the occurrence of circadian adrenocortical rhythms.

Adrenal Cortex↗
PubMed1982

[Treatment of elderly patients with hepatocellular carcinomas with mitomycin C and 5-fluorouracil].

Twenty elderly patients with hepatocellular carcinoma were treated with 5-fluorouracil (5-FU) at a daily dose of 200-300 mg per os, and with a combination of 0.3-0.35 mg/kg of mitomycin C (MMC) iv on day 1 and 8-10 mg/kg of 5-FU iv daily starting on day 1 for 5 consecutive days, repeating at 4 week intervals. According to the Koyama-Saito's criteria, there was no response in the 5-FU treatment, while a 20% (2/10) of response rate (2 partial responses) was obtained in the combination regimen. The durations of response in 2 partial responses were 7.3 and 4.0 months, respectively. The median survival with MMC and 5-FU was 3.4 months compared with 1.5 months with 5-FU alone, and the survival was correlated with tumor response. The combination produced more gastrointestinal toxicities and myelotoxicities compared to a single drug, but they were well tolerated. These results support the superiority of the combination of MMC and 5-FU over 5-FU alone in the treatment of elderly hepatocellular carcinoma.

Aged↗
PubMed1981

Inactivation of rat liver glucocorticoid receptor by molybdate. Effects on both non-activated and activated receptor complexes.

When freshly prepared glucocorticoid-receptor complex from rat liver cytosol was incubated at 23 degrees C in the presence of sodium molybdate, its subsequent binding to isolated nuclei, DNA-cellulose and ATP-Sepharose was blocked. In addition, binding to these acceptors by cytosol receptor complex fractionated with (NH4)2SO4 was also blocked by incubation of the complexes with 50 mM-sodium molybdate. However, molybdate had no effect on the binding of activated receptor complexes to ATP-Sepharose. Molybdate was also effective in extracting the nuclear- and DNA-cellulose-bound glucocorticoid-receptor complexes in a dose-dependent manner. Molybdate appears to exert its effects directly on the receptor by interacting with both non-activated and activated receptor forms.

Animals↗
PubMed1981

Extraction of DNA-cellulose-bound glucocorticoid-receptor complexes with sodium tungstate.

Glucocorticoid-receptor complex from rat liver cytosol, activated by warming at 23 degrees C or fractionation with (NH4)2SO4, was adsorbed over DNA-cellulose. This DNA-cellulose-bound [3H]triamcinolone acetonide-receptor complex was extracted in a dose-dependent manner by incubation with different concentrations of sodium tungstate. A 50% recovery of receptor was achieved with 5 mM sodium tungstate. Almost the entire glucocorticoid-receptor complex bound to DNA-cellulose could be extracted with 20 mM sodium tungstate. The [3H]triamcinolone acetonide released from DNA-cellulose following tungstate and molybdate treatment was found to be associated with a macromolecule, as seen by analysis on a Sephadex G-75 column. The glucocorticoid-receptor complex extracted by both the compounds sedimented as a 4 S entity of 5-20% sucrose gradients under low- and high-salt conditions. Addition of tungstate or molybdate to the preparations containing activated receptor had no effect on the sedimentation rate of receptor. However, addition of tungstate to non-activated receptor preparation caused aggregates of larger size. The tungstate-extracted glucocorticoid-receptor complex failed to rebind to DNA-cellulose even after extensive dialysis, whereas receptor in molybdate-extract retained its DNA-cellulose binding capacity.

Animals↗
PubMed1981

Surgical treatment for Graves' disease: a long term follow-up of 325 patients.

Postoperative thyroid status was classified into 6 categories on the basis of serum free thyroxine index (FTI), serum triiodothyronine (T-3) and serum TSH concentration. Review of 325 patients who underwent thyroidectomy for Graves' disease more than 4 years previously showed that 25 patients (7.7 per cent) had recurrent hyperthyroidism. Six patients (1.8 per cent) were classified as equivocal hyperthyroid since either FTI or T-3 was above the normal range. Two hundred and twenty-two patients (68.3 per cent) were unequivocally euthyroid and 33 patients (10.3 per cent) were euthyroid with elevated TSH levels. Twenty patients (6.2 per cent) were equivocal hypothyroid since either their FTI or T-3 values were below the normal range and TSH were increased. Hypothyroidism was present in 19 patients (5.8 per cent), of whom 11 had no clinical manifestation of thyroid dysfunction. The incidence of hypothyroidism did not correlate with the intervals between operation and review. The second review, performed in 189 patients 18 months after the first, showed that there was a change in thyroid functional status in 46 patients, of whom 32 had an increased level of function, including one hypothyroid and 7 equivocal hypothyroid patients who became euthyroid spontaneously. Thus postoperative hypothyroidism in some patients can recover without medication. Also thyroid function in some postoperative patients is not maintained at a fixed level but may fluctuate.

Adult↗
PubMed1981

Effect of cadmium on the isolated vas deferens from guinea-pig.

The effects of cadmium on the responses to the agonists, K, acetylcholine, noradrenaline, Ba and Ca were investigated in the isolated vas deferens from guinea pig. 1. The low concentration of cadmium enhanced the effects of tested agonists, and the enhancement was larger in order of K, Ba, Ca, noradrenaline=acetylcholine. 2. The high concentration of cadmium inhibited the effects of tested agonists with a dose-dependent manner. The inhibitory effect was weaker against the contraction by K and was stronger against the contractions by Ba, Ca, acetylcholine and noradrenaline. 3. The inhibitory effects of cadmium against the contractions by acetylcholine and noradrenaline were almost the same. 4. On the shape of contraction by K, cadmium showed the stronger inhibition against the tonic contraction than the phasic contraction. 5. The above mentioned results were mainly discussed on the Ca mobilization and the receptor selectivity.

Acetylcholine↗
PubMed1981

Direct effects of endogenous pyrogen on medullary temperature-responsive neurons in rabbits.

The effect of endogenous pyrogen (E.P.) injected directly into the tissue near the recording site were examined on the activities of the medullary temperature-responsive (TR) neurons in rabbits anesthetized with urethane. Endogenous pyrogen prepared from rabbit's whole blood was administered by a fine glass cannula (100-200 micrometer in diameter) in a fluid volume of 1 to 4 microliter. The cannula was fixed to the manipulator in parallel with a microelectrode and their tips were less than 0.05 mm apart. In rabbits with the intact preoptic/anterior hypothalamic (PO/AH) region, 4 warm-responsive neurons out of 7 were inhibited and 6 cold-responsive neuron out of 7 were excited by the direct administration of the E.P. In rabbits with lesions of the PO/AH, 5 warm-responsive neurons out of 9 were inhibited and 6 cold-responsive neurons out of 8 were facilitated by E.P. Antipyretics administered locally after the E.P. antagonized the pyretic effect, causing a return of the discharge of TR neuron to the control rate within 2.4 +/- 1.2 (mean +/- S.D.) min. The medullary TR neuron itself has the ability to respond to the E.P. and contributes to the development of fever.

Animals↗
PubMed1981

Histochemical changes of rat skeletal muscles induced by cold acclimation.

After cold acclimation of rats the augmentation of succinic dehydrogenase activity in the fast-twitch oxidative glycolytic (FOG) and the slow-twitch oxidative (SO) fibers was observed in entire regions of the soleus, the extensor digitorum longus, the plantaris, the longissimus and the gastrocnemius muscles. Furthermore, a tendency to increased proportion of the FOG and the SO fibers was observed more prominently in superficial regions than in deep regions of a large muscle such as the gastrocnemius muscle.

Adaptation, Physiological↗