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Biomedical subjects

M Tamai

Publications and source records attributed to M Tamai.

At least 325 records · Page 18Linked to original sources
PubMed1978

Development of haematopoietic colonies on the macrophage layer formed in the peritoneal cavity of S1/S1d mice.

The colony-forming ability of haematopoietic cells was examined on the macrophage layer formed in the peritoneal cavity of S1/S1d mice. The bone marrow cells of the congenic +/+ mice formed many macroscopic colonies on the macrophage layer of the S1/S1d mice although they did not form macroscopic colonies in the spleens of the same S1/S1d recipients. The size and the differentiation pattern of colonies on the macrophage layer of the S1/S1d mice were comparable to those of the colonies on the macrophage layer of the +/+ mice. There are two possible explanations for these results: (a) The microenvironmental defect of the S1/S1d mice has a more prominent effect on the development of spleen colonies than that of macrophage-layer colonies because 'Steel' locus may not be expressed significantly in the peritoneal macrophages or (b) because the cells that make colonies on the macrophage layer may be more differentiated cells than the multipotential stem cells that make colonies in the spleen.

Animals↗
PubMed1978

A criss-cross heart with concordant atrioventriculo-arterial connections. Report of a case.

A distinctive angiographic appearance is described in a case of "criss-cross" heart with concordant atrioventriculo-arterial connections. The atrial situs was normal, and the morphological right ventricle was superior to the left ventricle, and the ventricular septum was horizontal in position. Both ventricleswere connected by a small ventricular septal defect. The aorta was situated anteriorly and to the right of the pulmonary artery. Although the cardiac segment was the apparent [S,L,D] type, the heart had conconrdant atrioventriculo-arterial connections. The ventricular rotation of the solitus heart about the longitudinal and the anteroposterior axis affected the atrioventricular flows, the plane of the ventricular septum, the inflow and outflow tracts of the ventricles, the interrelationship of the great arteries, and the course of the left coronary artery. Using the recent definition of criss-cross heart, we classified the heart as solitus-concordant (l-rotated) -normal.

Arteries↗
PubMed1978

The pineal gland does not control rod outer segment shedding and phagocytosis in the rat retina and pigment epithelium.

Diurnal patterns of retinal outer segment shedding and phagocytosis by the pigment epithelium were examined in pinealectomized, superior-cervical-ganglionectomized, and sham-operated rats. Phagocytosis was quantitatively similar in all groups. Sharp increases in the number of large phagosomes were observed soon after lights were turned on in the tree sets of animals. Pinealectomized animals kept in constant darkness over a 24 hr period also exhibited normal shedding patterns. Our results suggest that the pineal does not exert a major influence on the daily rhythms of shedding and phagocytosis observed in the retina-pigment epithelium unit.

Animals↗
PubMed1978

Hematologic changes during spleen colony development in nonirradiated mice.

The mechanism of spleen colony formation in nonirradiated mice was investigated. When the spleen cells of C57BL mice immunized against CBA-T6T6 mice were injected into the nonirradiated BT6F1 (C57BL X CBA-T6T6) hybrid mice, the number of hematopoietic stem cells (CFU-S of C57BL mouse origin that settled in the spleen of the BT6F1 mice continued to decrease in the first 9 days and then started to increase, with a doubling time of about 36 hr. Colonies were detected on the surface of the spleen 16-22 days after the cell injection. The slower appearance of spleen colonies in nonirradiated mice (compared with 6-10 days in the irridiated animals) appears to be due to retarded start of differentiation and to the prolonged doubling time of CFU-S in non-irradiated mice.

Animals↗
PubMed1977

Development of hematopoietic spleen colonies in nonirradiated genetically normal mice.

The question as to whether prior irradiation or injection of cytotoxic drugs is essential for the development of spleen colonies was examined in genetically normal mice. Mixtures of lymph node and bone marrow cells from C57BL mice were injected into (C57BL X CBA-T6T6) F1 hybrid mice without pretreatment. Hematopoietic nodules were observed in the spleens of F1 hybrid mice killed 18 days after injection. The average number of nodules increased linearly with increased numbers of injected bone marrow cells. Hematopoietic stem cells (CFU-S) and dividing cells in the nodules were shown to be of C57BL origin. Histologic examination showed that erythroid cell colonies predominated over granulocytic cell colonies. These results suggest that any kind of treatment that causes the depletion of CFU-S in the spleen of hosts would provide a suitable environment for the production of colonies by transplanted CFU-S.

Animals↗
PubMed1976

Progesterone metabolism in vitro by testes from germ cell-free mice of different ages.

Androgen biosynthesis in vitro by testes from (C57BL X WN)F1-WV/Wn (congenitally germ cell-free) and +/+ (normal) mice of different ages was investigated using [3H]progesterone as substrate. At all ages examined, the seminiferous tubules of the WV/Wn genotype were largely devoid of germ cells. However, the age dependent pattern of progesterone metabolism by germ cell-free testes were similar to that by normal testes. Conversion of progesterone to 5alpha-reduced 17-hydroxy-C21 and C19-steroids such as 3alpha,17alpha-dihydroxy-5alpha-pregnan-20-one, androsterone, 5alpha-androstane-3alpha,17beta-diol and 5alpha-androstane-3beta,17beta-diol was high in testes of 28- and 35-day-old mice of both groups. However, these 5alpha-reduced metabolities were found to be formed in very small amounts or not formed at all in testes of 20-, 120- and 150-day-old mice of both groups, in which conversion of progesterone to 17alpha-hydroxyprogesterone, androstenedione and testosterone was observed. It appears that in the absence of germinal cells, there is a normal increase and reduction of 5alpha-reductase activity in one or more classes of remaining cells during maturation of the testis.

Aging↗
PubMed1976

Diagnosis of endocardial cushion defect with cross-sectional and M-mode scanning echocardiography. Differentiation from secundum atrial septal defect.

Twelve cases of endocardial cushion defect were studied before and after operation with ultrasono-cardiotomography (tomography) cross-sectional echocardiography, two-dimensional echocardiography, B-scan echocardiography) and M-mode scan along a horizontal section of the heart. For comparison, 20 healthy subjects, 18 cases of mitral valvular disease, 4 cases of congestive cardiomyopathy, 1 case of partial anomalous pulmonary venous drainage, and 25 cases of atrial septal defect of secundum type were also examined with the same technique. In cases without cardiac malformation, the echo of the anterior mitral valve was usually continuous medially with that of the interatrial septum in the horizontal plane at the level of the membranous septum. This feature was clearly recorded in all cases with right heart enlargement. In ostium secundum atrial septal defect the echo of the anterior mitral valve continued into that of the interatrial septum. An echo interruption was shown, indicating the defect itself to be in the middle part of the interatrial septum. In all the cases of endocardial cushion defect which we examined discontinuity was shown between the echo of the anterior mitral valve and that of the interatrial septum. This discontinuity was interpreted as indicating the defect itself. The mitral valve ring echo was close to the basal end of that of the interventricular septum, possibly reflecting an abnormal attachment of the mitral valve. In all cases, after operation, the echo of the artificial interatrial septum was recorded, continuous with that of the anterior mitral valve. The features of the echocardiographic sweep from the anterior mitral valve to the interatrial septum were thus different in the three groups. These echocardiographic differences are thought to correspond to the anatomical differences between the normal, atrial septal defect of secundum type, and endocardial cushion defect, and are essential features differentiating them from each other.

Adolescent↗
PubMed1975

An unusual pattern of the mitral echocardiogram observed in cases of congestive cardiomyopathy and other myocardial diseases.

(1) Narrowness of the early-diastolic and presystolic peaks on the echo curve of the anterior mitral leaflet and an abnormal step formation at the middle or higher level on the descending limb of the presystolic peak were observed in 7 cases with congestive cardiomyopathy or myocardial fibrosis, 1 case with myocardial infarction, and 1 case with cardiomyopathy due to progressive muscular dystrophy. (2) This abnormal pattern is considered to be closely related to the myocardial condition in the above-mentioned diseases. (3) Probable mechanisms for this pattern formation are considered as follows: (i) a sudden reduction of distensibility of the left ventricle after filling of the ventricle over a certain limit near full-filling, and impaired ventricular contractility, (ii) restriction in the mobility of the mitral valve and its chardae due to thier inability to adapt themselves to a developed dilatation of the left ventricle. (4) A similar presystolic step formation on the echo curve of the anterior mitral leaflet was observed in 3 of 25 cases of hypertrophic cardiomyopathy of Goodwin's sense. Differences between the myocardial state in congestive cardiomyopathy or in similar myocardial diseases and that in hypertrophic cardiomyopathy were also discussed.

Adolescent↗