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Biomedical subjects

K Imamura

Publications and source records attributed to K Imamura.

At least 397 records · Page 22Linked to original sources
PubMed1976

Ultrastructural changes in hypertrophied myocardium of spontaneously hypertensive rats.

In seven arbitrarily selected groups of 3-, 5-, 9-, 11-, 15-, and 21-week and one-year-old spontaneously hypertensive rats (SHR) (F25-26), qualitative as well as quantitative light and electron microscope studies were conducted on the myocardium in the left ventricular papillary muscle and lateral wall. Age-and body-weight-matched groups of normotensive Wistar-Kyoto rats were employed as controls. In the strain of SHR used in this study blood pressure was significantly higher than in the controls in the 7th week of age, reached sustained levels (approximately 180 mmHg) in the 15th week of age and remained higher thereafter. The heart weight/body weight ratio gradually increased in SHR after the 15th week of age. In 3-week-old SHR, there was no significant difference in fine structure of the myocardium in comparison with control animals. The cardiocytes were small in size and rapidly growing. Myofibrillogenesis seemed to occur in association with juvenile forms of intercalated discs, subsarcolemmal dense mats, occasional Z band expansions and unorganized filamentous structures in the periphery of preexisting myofibrils. In 5- and 9-week-old SHR, the muscle fiber diameters in the papillary muscle were significantly larger than those in control animals of the same age. Subcellular structures of many cardiocytes were, however, apparently equal in both papillary muscle and lateral wall of the left ventricle in SHR and control animals. In 11-week-old SHR, the cardiocytes were moderately hypertrophied in both papillary muscle and lateral wall. The myofibrils were significantly increased in mass in association with altered intercalated discs, extended subsarcolemmal dense mats and unorganized filamentous structures in the periphery of preexisting myofibrils. Focal interstitial fibroses occurred in in the myocardium, and tunnel capillaries appeared in some hypertrophied cardiocytes. In 15-week-old SHR, the cardiocytes had markedly hypertrophied in accordance with the establishment of sustained hypertension. The intracellular volume ratios of myofibrils and T system had increased significantly whereas the mitochondrial volume had markedly decreased resulting in a significant increase in the myofibril/mitochondria volume ratio. There were marked changes in the intercalated discs associated with numerous immature sarcomers, and frequent abnormal Z band expansions. Interstitial fibroses had markedly increased in number and extent. In 21-week-old SHR, in addition to findings similar to those in 15-week-old SHR, heterogeneous changes of the contractile material, mitochondria and sarcoplasmic matrix were more prominent, suggesting heterogeneous malfunctions in later stages of cardiac hypertrophy. In one-year-old SHR, subcellular changes in many cardiocytes qualitatively resembled those in 21-week-old SHR. Interstitial fibroses and tunnel capillaries were also increased in extent and number...

Age Factors↗
PubMed1975

Daunorubicin, cytosine arabinoside, 6-mercaptopurine riboside, and prednisolone (DCMP) combination chemotherapy for acute myelogenous leukemia in adults.

Thirty-seven adults with acute myelogenous leukemia (AML) were treated with a combination of daunorubicin, cytosine arabinoside, 6-mercaptopurine riboside, and prednisolone (DCMP) for remission induction. Twenty-three of 37 patients (62.2%) achieved complete remission, three, partial remission and 11, failure. Patients with prior therapy responded as well as patients without it. The median survival time of the patients who received DCMP for their initial remission induction therapy was 10.3 months and that of the patients who obtained complete remission was 17 months. Complete remission occurred in 21 out of 28 patients (75%) less than 40 years old but in only two out of nine patients (22.2%) more than 40 years old. The most common toxic effects were severe myelosuppression and liver function abnormalities. DCMP therapy is an effective remission induction chemotherapy for adults with AML.

Adolescent↗
PubMed1975

Pathophysiology of aganglionic colon segment: an experimental study on aganglionosis produced by a new method in the rat.

Experimental aganglionosis was produced successfully in a colonic segment proximal to the peritoneal reflection by intraluminal filling under tension of the colorectum of rats with 0.01% corrosive sublimate in normal saline solution. Where the length of aganglionic segment was more than 3 cm, ileus appeared and megacolon proximal to a narrow segment was observed. Histologically and histochemically, a total denervation state was observed in the aganglionic segment, in contrast to findings in narrow segments of Hirschsprung's disease, in which intramural extraneous nerves are known to be increased. The fact that a definite narrow segment like that seen in Hirschsprung's disease appeared at the portion of the colon in which experimental aganglionosis was produced indicates that a narrow colonic segment certainly can be produced without presence of any intramural extraneous nerves, although the possibility that the presence of such nerves may exaggerate the narrowing cannot be denied. The fact that the cases in which length of aganglionosis was less than 2.5 cm did not have an ileus suggests that there may be some contributing factors other than aganglionosis in the etiology of Hirschsprung's disease of ultrashort segment, if this entity of the disease really exists. Aperistalsis observed in experimental aganglionic segments and that observed in aganglionotic segments of Hirschsprung's disease seem to be based on a common main factor, i.e., absence of the nonadrenergic, noncholinergic nerves.

Animals↗