PubMed Health⌕ Search

Biomedical subjects

S Takama

Publications and source records attributed to S Takama.

At least 19 recordsLinked to original sources
PubMed1987

Reduction and spectroscopic properties of hemoglobins M.

Reduction of five hemoglobins M (Hbs M) was studied using three enzymatic reducing systems; namely NADPH-flavin reductase from human erythrocytes, NADH-cytochrome b5 reductase from human erythrocytes and ferredoxin-NADP reductase from spinach. Under anaerobic conditions, abnormal chains in Hb M Saskatoon were reduced by all three systems, whereas those in Hb M Milwaukee were reduced by the latter two enzyme systems only. The abnormal chains in Hb M Hyde Park were reduced only by the ferredoxin-NADP reductase system. On the other hand, the abnormal chains in Hb M Iwate and Hb M Boston were reduced by sodium dithionite, but not by the three enzymatic reducing systems. Absorption and circular dichroic (CD) spectra of these Hbs M were compared with those of Hb A to examine their structural abnormalities. Absorption and CD spectra of four Hbs M except Hb M Milwaukee were remarkably different from those of Hb A. Conformational differences between alpha- and beta-abnormal Hbs M were reflected in the CD spectrum of the ultraviolet region. The difference between the proximal and distal histidine-replaced Hbs M was also observed in the CD spectra of the visible region.

Circular Dichroism↗
PubMed1986

Ultracytochemistry of pancreatic damage induced by excess lysine.

The ultracytochemical changes induced in the pancreas by a single large dose of lysine (400 mg/100 g body weight) were studied in male Wistar rats of 7 weeks old. The first changes in the acinar cells were marked swelling of mitochondria with increase in their calcium content and decrease in their ATP content. Early calcium deposits seemed to occur in the matrices of swollen mitochondria and later various patterns occurred. These findings suggested that damage of the acinar cells by excess lysine resulted in breakdown of the mitochondrial membrane barrier to calcium as a very early abnormality, and that extracellular calcium then entered the mitochondrial matrices and inhibited mitochondrial function. Subsequently focal areas of the cytoplasm were degraded. Autophagic vacuoles appeared in these areas, and then acid phosphatase activity in their periphery as a result of fusion with lysosomes. The reaction of acid phosphatase was demonstrated in the locally degraded rough endoplasmic reticulum within or around autophagic vacuoles, suggesting that the endoplasmic reticulum as well as lysosomes participated in the intracellular degradation of cytoplasmic organelles in damaged acinar cells.

Acid Phosphatase↗
PubMed1985

Hemoglobin M: effect of the proximal or distal histidine replacement on circular dichroism in the visible region.

To examine the effects of a replacement of the proximal or the distal histidine on the structure of hemoglobin (Hb), absorption and circular dichroic (CD) spectra of five species of Hbs M in the visible region were measured. Four Hbs M had a characteristic but a similar absorption spectrum upon amino acid substitution, however, the proximal histidine replaced Hbs M (Hb M Iwate and Hb M Hyde Park) showed considerably different CD spectra from those of the distal histidine replaced ones (Hb M Boston and Hb M Saskatoon). The former exhibited large positive CD but the latter gave a complex CD spectrum with positive and negative extrema. On the other hand, absorption and CD spectra of Hb M Milwaukee did not changed very much from those of Hb A.

Circular Dichroism↗
PubMed1985

Ultrastructure of tumor cell interaction with alveolar macrophages stimulated by vitamin A.

F344 rats were given vitamin A for four consecutive days and then their alveolar macrophages (AM phi) were obtained by bronchopulmonary lavage of the lung. Compared with unstimulated AM phi, AM phi from rats given vitamin A had more numerous and longer cytoplasmic projections, and these projections had many knobs on their sides and tip. The AM phi became attached to syngeneic mammary adenocarcinoma cells at many focal points and the tumor cells then lost surface microvilli around the contact zones. Detachment of the knobs from the projections on AM phi was often observed in areas of close association between AM phi and tumor cells. The detached knobs were 250 nm in diameter, gave a positive reaction for acid phosphatase, and frequently became attached to the surface of tumor cells. Then, many of the tumor cells in the vicinity of AM phi exhibited cytolytic changes. It is concluded that the cytotoxicity of stimulated AM phi is due to their attachment to the surface of tumor cells and their release of particles with acid phosphatase activity into the narrow space between the cells, and then to uptake of these particles by susceptible tumor cells.

Animals↗
PubMed1985

Dietary effects on pancreatic lesions induced by excess arginine in rats.

The effect of nutrition on the incidence of pancreatic damage was studied. Injection of excess arginine was found to cause more massive necrosis of the acinar cells after 24 h in malnourished rats (those given 50 g casein/kg diet) than in well-nourished rats (those given 200 g casein/kg diet). Ultrastructural examination showed that whorl formation of the endoplasmic reticulum, decreases in the number of zymogen granules and formation of vacuoles in the cytoplasm were more marked in rats given 50 g casein/kg diet. Degradation of zymogen granules within vacuoles in the damaged cells was frequently observed in rats given 200 g casein/kg diet. Necrosis of adipose tissue was associated with pancreatic damage more frequently in rats given 200 g casein/kg diet; rats with large amounts of zymogen granules in the acinar cells showed particularly severe necrosis of adipose tissue. Rats given 50 g casein/kg diet did not show necrosis of adipose tissue. These results indicate that in the malnourished state there were more marked arginine lesions of the pancreas in which to study cellular and histologic changes than in the well-nourished state and that the occurrence of necrosis of adipose tissue may be related to a high content of zymogen granules in the acinar cells before pancreatic damage.

Adipose Tissue↗