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Biomedical subjects

K Shimamura

Publications and source records attributed to K Shimamura.

At least 253 records · Page 14Linked to original sources
PubMed1981

Effects of abrupt cessation of treatment with clonidine and guanfacine on blood pressure and heart rate in spontaneously hypertensive rats.

Present experiments were undertaken to compare the effects of clonidine and guanfacine withdrawal on blood pressure in spontaneously hypertensive rats. Five week oral administration of clonidine at a dose of approximately 300 microgram/kg/day produced a significant hypotension. After acute interruption of clonidine administration, a marked blood pressure rise was observed. Peak blood pressure rise was reached within 24 hours after clonidine withdrawal. A significant increase in plasma norepinephrine concentration was observed when clonidine treatment was discontinued. On the other hand, long-term administration of guanfacine at a dose of approximately 3 mg/kg/day produced a significant hypotension. After a five week administration of guanfacine, abrupt cessation did not produce a rapid blood pressure rise. Catecholamine concentration in urine and plasma was not influenced either by guanfacine administration or its withdrawal.

Animals↗
PubMed1981

Removal of fibrin thrombi in disseminated intravascular coagulation (DIC). Morphological studies.

Twenty-one cases of untreated disseminated intravascular coagulation (DIC) were morphologically studied with special reference to the removal processes of the microthrombi. Four types of microthrombi were identified: intraluminal microthrombi with or without cellular reaction, and endothelialized microthrombi with or without fibroblastic reaction. They seem to indicate the course and the degree of disappearance of the microthrombi.

Adolescent↗
PubMed1981

The causes of death of tuberculosis patients in chemotherapy era.

Detailed analysis was made on causes of death among tuberculosis patients hospitalized in national sanatoria and those registered as tuberculosis at the breath centres. Deaths directly or indirectly related to tuberculosis could be divided into the following four major categories; dying with active tuberculosis process shortly after the detection due to the delay in detection, with active process combined with the emergence of drug resistance long after the detection due to failure in treatment, with sequela of tuberculosis mainly cardiopulmonary insufficiency, and with other conditions listed as non-tuberculosis death but attributable to either active or inactive tuberculosis. The ratio of these four categories at present in Japan is estimated to be approximately 1:1:2:4-6. The results indicate that the magnitude of tuberculosis problem should not be underestimated through decline in the crude tuberculosis mortality.

Antitubercular Agents↗
PubMed1981

In vivo effects of anti-asialo GM1. I. Reduction of NK activity and enhancement of transplanted tumor growth in nude mice.

Intravenous injection of anti-asialo GM1, which has been shown to eliminate natural killer (NK) activity in vitro in the presence of complement, completely abolished NK activity against lymphoma cell line (YAC-1) in spleen cells from athymic nude mice as well as from conventional mice. An immunofluorescence study revealed a decreased number of asialo GM1 positive cells in the spleens of mice injected with anti-asialo GM1 than in those of mice injected with normal rabbit serum. In the nude mice with reduced NK activity, incidence of tumor take and the growth were enhanced when syngeneic (RL male-1), and allogeneic (YAC-1) tumors and human tumors were transplanted subcutaneously. These results strongly suggest that NK cells play an important role in transplanted-tumor growth in vivo.

Animals↗
PubMed1981

Effect of clonidine on the function of the adrenal medulla in rats.

Intravenous administration of clonidine at a dose of 30 microgram/kg produced significant decrease both in spontaneous adrenal nerve activity and in adrenal catecholamine secretion rate in rat. These findings could indicate that clonidine decreases catecholamine secretion from the adrenal medulla via the central nervous system.

Adrenal Medulla↗
PubMed1981

[Effect of clonidine on the function of adrenal medulla in rats (author's transl)].

The present experiments were undertaken to elucidate the effect of clonidine on the function of adrenal medulla both in normotensive rats and spontaneously hypertensive rats (SHR). In urethane anesthetized rats, efferent discharge rate of splanchnic nerve and sympathetic adrenal nerve branch (adrenal nerve) was recorded. Plasma catecholamine concentration of adrenal venous blood was determined radioenzymatically. Catecholamine secretion rate from left adrenal gland was calculated. In normotensive rats, clonidine produced a significant decrease in efferent nerve activity of the splanchnic nerve and adrenal nerve. It was also demonstrated that clonidine produced a significant decrease in adrenaline secretion rate from adrenal gland. Statistically insignificant decrease in noradrenaline secretion rate from adrenal gland was observed. Clonidine induced hyperglycemia was not related to the rapid fall in adrenal efferent nerve activity induced by clonidine. In debuffered rats, clonidine produced a decrease in the adrenal efferent nerve activity. In SHR, clonidine produced a significant decrease in adrenal efferent nerve activity and adrenaline secretion rate from adrenal gland. With regard to the response of adrenal efferent nerve activity to clonidine, decreased activity appeared more remarkably in normotensive rats as compared with that in SHR. These findings suggest that clonidine decreases adrenaline secretion rate from the adrenal glands by central actions in rats.

Adrenal Medulla↗
PubMed1980

[Plasma catecholamine content in hypertensive subjects and spontaneously hypertensive rats using radioenzymatic assay (author's transl)].

The present experiments were undertaken to determine the plasma catecholamine content in normotensive, slightly hypertensive humans and spontaneously hypertensive rats using radioenzymatic assay. In addition, attempts were made to compare radioenzymatic assay with a fluorometric technique, using high performance liquid chromatography with respect to human plasma catecholamine content. Human plasma catecholamine content in normotensive subjects at rest was 250 +/- 61 pg/ml (mean +/- S.E.) for norepinephrine and 37 +/- 22 for epinephrine. Immediately after treadmill exercise, human plasma norepinephrine content significantly increased. In 14 patients with mild essential hypertension, plasma norepinephrine was 460 +2- 128 pg/ml with the subject in a supine position and 1030 +/- 151 in the case of treadmill exercise. Thus, there was a statistically significant difference. With regard to plasma catecholamine content in spontaneously hypertensive rats, the norepinephrine content was 816 pg/ml, epinephrine was 209 pg/ml and dopamine was 505 pg/ml, on an average. After comparing this method with the fluorometric technique using high performance liquid chromatography, we confirmed that the former requires much smaller sizes of samples and has much the same sensitivity as the latter.

Adult↗
PubMed1979

Effects of long-term administration and withdrawal of clonidine on activity of sympathetic efferent nerve unit in spontaneously hypertensive rats.

Daily administration of clonidine for 5 weeks (approx. 300 micrograms/kg/day, p.o.) produced significant decreases in blood pressure and renal sympathetic efferent activity in spontaneously hypertensive rats (SHR). After cessation of clonidine administration, blood pressure and sympathetic nerve activity recovered rapidly from the depressed levels to the untreated control levels. These findings could indicate that clonidine-induced hypotension and its rapid recovery to control after withdrawal of clonidine are caused by corresponding changes in sympathetic efferent nerve activity.

Animals↗
PubMed1979

Pharmacokinetics of verapamil in man.

Verapamil was given intravenously (10 mg) and orally (120 mg) in six healthy subjects. After intravenous administration, the serum levels in all subjects declined bi-exponentially. Thereupon, pharmacokinetic parameters were calculated using a two-compartment open model. The half-lives of distribution (T 1/2 alpha) and elimination (T 1/2 beta) phases showed 0.23 hour and 4.21 hour on an average respectively. The apparent volume of distribution [Vd (area)] showed 2.51 1/kg and body clearance (C1b) showed 500.64 ml/min on an average. Renal clearance was smaller than normal human creatinine clearance. After oral administration, the time to reach peak blood level (Tmax) was reached within 1.84 hour and the peak serum concentration showed 219.09 ng/ml on an average. The bioavailability was only 22.47% on an average. Verapamil produced a marked prolongation of PQ interval on electrocardiogram and the degree of PQ interval prolongation was closely related to the increase in serum concentration of this compound. QRS, QTc and RR interval were not changed by this compound.

Administration, Oral↗
PubMed1978

Polypoid carcinoma of the esophagus. A unifying term for "carcinosarcoma" and "pseudosarcoma".

Polypoid carcinomas with spindle-cell sarcomatous features have been designated either as carcinosarcoma or pseudosarcoma. The distinction between these two tumors has depended on the presence of "intermingling" of the carcinomatous and sarcomatous components in so-called carcinosarcoma. But unlike the carcinosarcoma, the sarcomatous component in pseudosarcoma has been considered benign. A polypoid tumor of the esophagus in a 57-year-old male was predominantly composed of spindle cell, sarcomatous cells. The presence of adjacent intraepithelial epidermoid carcinoma with transitional and ultrastructural features confirmed the epithelial origin of this tumor. Because of the absence of "intermingling," the primary tumor was considered to be a pseudosarcoma. However, our postmortem examination showed metastases composed of both carcinomatous and sarcomatous features. A review of the literature on carcinosarcomas and pseudosarcomas shows that only one case of pseudosarcoma reported by Hughes and Cruickshank showed a similar situation and indicates that the sarcomatous component in pseudosarcomas has the same metastatic potentiality as has been reported in carcinosarcomas. We conclude from these studies a basic similarity of the carcinosarcoma and pseudosarcoma. The term polypoid carcinoma is proposed for both these lesions.

Bronchial Fistula↗