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S Kanamura

Publications and source records attributed to S Kanamura.

At least 73 records · Page 4Linked to original sources
PubMed1984

Development of structural heterogeneity of mitochondria in mouse hepatocytes.

The volume and shape (the axial ratio:length/diameter) of mitochondria in periportal and perihepatic hepatocytes from newborn, 5 days old, 10 days old and adult male ddY mice were analysed by quantitative electron microscopy. In newborn animals, the volume and relative histogram of the axial ratio were not significantly different between periportal and perihepatic cells. Thereafter, the volume did not change significantly in periportal cells, whereas it decreased between 5 days of age and the adult in perihepatic cells. In adult animals, the volume in perihepatic cells was 26% of that in periportal cells. The relative histogram of the axial ratio for periportal cells deviated significantly to smaller values than in that for perihepatic cells in 5 days old, 10 days old and adult animals. Thus, the structural heterogeneity of hepatocyte mitochondria, evident in adult animals, is not present in newborn animals but arises during postnatal development.

Animals↗
PubMed1983

Effect of castration and testosterone replacement on high glucose 6-phosphatase activity in principal cells of the mouse epididymis.

Glucose 6-phosphatase activity is higher in the principal cell than in other cell types in the terminal segment and caudal half of the middle segment of the mouse epididymis. Effect of castration and testosterone replacement on the high enzyme activity in the principal cell was studied in the terminal segment and the caudal half of the middle segment (cytochemical study), and in the whole epididymis (biochemical study). Ten, 20, or 30 days after castration, the abundant amount of reaction product seen in principal cells from intact control animals decreased to the level in basal cells, halo cells, and smooth muscle cells. However, in animals treated with testosterone following castration, the reaction product in principal cells remained abundant. Changes in the biochemical activity after castration or testosterone administration following castration paralleled the cytochemical results. Thus, the high activity in the principal cell is under the control of testosterone.

Animals↗
PubMed1983

Observation of cytochemical alkaline phosphatase activity on the plasma membrane of cultured rat hepatocytes by backscattered electron imaging.

Distribution of alkaline phosphatase (ALPase) activity on the plasma membrane of rat hepatocytes in primary monolayer culture was observed using the backscattered electron image (BEI) mode. Apparent reaction product was seen in hepatocytes cultured for 48 or 72 hours in a concentration of 8 X 10(5) cells per ml, and those cultured for 72 or 96 hours in a concentration of 6 or 4 X 10(5) cells per ml. The reaction product was observed as scattered fine dots, as spots, and as bands along the cell edge, with high contrast in flattened polyhedral hepatocytes forming cell trabeculae. The deposition of the reaction product was generally more abundant at the periphery of the cell trabeculae. X-ray microanalysis revealed that the reaction product contains both lead and phosphorus as real ALPase reaction product. In transmission electron microscopy, the reaction product was exclusively localized on the external surface of the plasma membrane. However, the plasma membrane adjoining the culture substratum was devoid of the reaction product. Further, the highest biochemical ALPase activity appeared in earlier culture stages when the density of cultured cells was larger. Thus, during a few days of culture, ALPase activity increases on the plasma membrane predominantly at the periphery of the hepatocyte trabeculae. This increase in the activity might be related to the mechanism of preserving the cell shape.

Alkaline Phosphatase↗
PubMed1983

Cytochemical glucose-6-phosphatase activity in the cells of mouse pancreas and submandibular gland.

Ultrastructural localization of glucose-6-phosphatase activity was studied in the cells of the pancreas and submandibular gland of the mouse using a incubation medium modified from that of Wachstein & Meisel (1956). In pancreatic acinar cells, the reaction product for the enzyme activity was not found even after 90 min of incubation with three changes of the medium. However, the reaction product was localized in the endoplasmic reticulum and nuclear envelope of all other cell types composing the pancreas and submandibular gland. The reaction product appeared in moderate to abundant amounts in acinar cells and striated duct cells of the submandibular gland, and in the B cells, A and D cells of the pancreatic islet, but it was scarce in other cell types.

Animals↗
PubMed1983

Binding and internalization of 125I-glucagon in hepatocytes of intact mouse liver. An autoradiographic study.

Localization of labeled material in hepatocytes of intact mouse liver injected via the portal vein with 125I-glucagon was studied. At 3 minutes after pulse injection of the labeled glucagon, most grains were localized associated with the plasma membrane. At 10 min after the injection, the grains were distributed throughout the cytoplasm and did not appear localized exclusively in any specific cell organelles. At 20 min after the injection, the labeled material appeared decreased, and was not yet localized exclusively in any specific cell organelles. Thus, in hepatocytes of intact liver, labeled glucagon is internalized more rapidly than in freshly isolated hepatocytes (Barazzone et al. 1980), and there appear to be no cell organelles in which internalized glucagon is preferentially localized.

Animals↗
PubMed1982

Development of ultrastructural heterogeneity among hepatocytes in the mouse.

Ultrastructural stereological analyses of periportal and centrilobular hepatocytes of newborn, 5- and 10-day-old, and adult male ddY mice were carried out to study the postnatal development of the morphologic heterogeneity among hepatocytes. In newborn animals, the periportal and centrilobular cells did not differ in the volume densities of the smooth and rough endoplasmic reticulum; in the volume and numerical densities of the mitochondria, lysosomes, peroxisomes, and lipid droplets; or in the shape (the axial ratio) of the mitochondria. In 5-day-old animals, the volume densities of the mitochondria and rough endoplasmic reticulum were greater in periportal cells than centrilobular cells, and the volume density of the smooth endoplasmic reticulum was greater in centrilobular cells than periportal cells. In 10-day-old animals, a further difference was seen in the numerical density of the mitochondria, which was greater in centrilobular cells than periportal cells. Adult hepatocytes showed also a difference in the axial ratio of the mitochondria, which was greater in centrilobular than periportal cells; there was no difference in the volume density of the rough endoplasmic reticulum. When the data were expressed as volume and number per hepatocyte, the patterns of sublobular distributions of these organelles differed from the patterns seen in the volume and numerical density data, mainly in adult animals. This difference was caused by the marked increase in hepatocyte volume between 10 days of age and adulthood, especially in centrilobular cells. The results show that, in general, the ultrastructural heterogeneity among hepatocytes, evident in adult animals, is not present in newborn animals but arises during postnatal development, and suggest the occurrence of a lobular gradient in postnatal development of hepatocyte functions.

Animals↗
PubMed1980

The pattern of glycogen withdrawal within the liver acinus during fasting.

Intraacinar regionality in glycogen withdrawal during fasting was studied in the liver of the mouse. When animals were fasted from 10.00 a.m. onwards, glycogen withdrawal began in zone 1, spreading gradually to zone 3, and after 12 h glycogen disappeared throughout the acinus. After 24 h new glycogen accumulated in various portions of the acinus. However, when animals were fasted from 10.00 p.m. or 12 midnight to the following morning, glycogen was withdrawn evenly throughout the lobule. After 24 h glycogen disappeared throughout the acinus. These results show that there is a heterogeneity in the hepatocyte with respect to glycogen withdrawal during fasting by day but not by night. Therefore, the discrepancy in reported results on the intraacinar distribution of glycogen during fasting is probably due to the time of sacrificing animals.

Animals↗
PubMed1980

The heterogeneity of hepatocytes during the postnatal development of the mouse.

Development of the hepatocyte heterogeneity was studied histochemically during the postnatal period. At birth ornithine carbamoyltransferase (OCT). succinate dehydrogenase (SDH) and NADH dehydrogenase (NADHDH) activities were evenly distributed throughout the liver acinus. Slightly uneven distribution within the acinus appeared at 3 days after birth in SDH and at 4 days after birth in OCT and NADHDH, changing to that of adult type at 10 or 12 days after birth which is characterized by a marked difference in the activities between zone 1 and 3. However, in animals of all age groups studied, glycogen was decreased mainly in zone 1 and 2 after 6 or 10 h of fasting and glucose 6-phosphatase activity was markedly reduced or disappeared in zone 3 and often in zone 2 after carbon tetrachloride administration. The results show that so-called "functional and structural heterogeneity among hepatocytes" consists of at least two different components, that formed gradually during the postnatal development and that existing already at birth.

Age Factors↗
PubMed1979

Postnatal changes in the distribution of lipid droplets within the liver lobule of the mouse.

The changes in the distribution of lipid droplets in the liver lobule were studied during the postnatal development of the mouse. At birth, and 1 day after birth, lipid droplets were evenly distributed throughout the lobule. A slightly uneven distribution of the droplets, more in centrilobular areas, appeared 2 days after birth. After this the difference in the number of droplets between the cells of the centrilobular and periportal areas became progressively more marked reaching a maximum by 17 days of age, and then decreasing to the adult level between 21 and 24 days. Thus, heterogeneity among hepatocytes with respect to lipid content is not present in newborn mice but develops gradually during the postnatal development.

Aging↗
PubMed1975

Postanal changes in the localization of glucose 6-phosphatase activity within the liver lobule of the mouse.

The change in the localization of glucose 6-phosphatase activity within the liver lobule of the mouse was studied during development. From one day before birth to three days after birth, a uniform localization of the activity was observed throughout the lobule. This uniform localization of the acitvity gradually changed to that of the adult type, characterized by a relatively higher activity in periportal areas, between three to ten days of age. This indicates that the postnatal growth of the liver is accompanied by a change in the pattern of the localization of this enzyme activity within the liver lobule. Further, the biochemical results showed that the elevated activity after birth was reduced to the level seen in adult at ten days of age. Thus, the reduction in the level of the enzyme activity during ten days after birth corresponds to a redistribution of the enzyme activity within the liver lobule.

Animals↗
PubMed1975

Sensitivity of glucose 6-phosphatase activity to glutaraldehyde.

The effect of glutaraldehyde fixation on glucose 6-phosphatase activity in mouse liver was investigated. After transparenchymal perfusion with 2% glutaraldehyde for 1.5 minutes, the activity of the recovered enzyme was higher than those reported for acid phosphatase and aryl sulfatase activities after fixation under similar condition, and an abundant deposition of reaction product was observed in hepatocytes. Subsequent immersion in the same fixative solution for 30 minutes after 4 degrees C resulted in only a slight decrease in the activity. However, the activity was almost completely destroyed after 3 hours of immersion fixation at 4 degrees C following the perfusion. Therefore, the enzyme can be said to be aldehyde-sensitive when a long fixation time is used, but not aldehyde-sensitive during a short fixation time.

Acid Phosphatase↗
PubMed1975

Short term culture of dissociated rat submandibular gland cells.

Submandibular glands of 4-week-old rats were dissociated by a procedure involving digestions with collagenase and hyaluronidase, chelation with ethylenediaminetetraacetic acid, and mechanical force. The isolated cells were purified by centrifugation in a Ficoli solution and were maintained in culture for 36 hours. On the basis of trypan blue exclusions, about 70 per cent of the dissociated cells were viable. Electron microscopic observations indicated that the isolated acinar cells and intercalated and striated duct cells retained their essential in situ ultrastructural characteristics. During a 36-hour culture period the number of viable cells declined to about 40 per cent, and the various cell types formed mixed aggregates. The ultrastructural features of the intercalated and duct cells changed relatively little, but the acinar cells revealed several structural alterations. These included a decrease in the number of the secretory granules, fusions of the secretory granules, and an increase in the rough surfaced endoplasmic reticulum. In general, the polarity of acinar cells became less distinct. The endogenous peroxidase activity in the acinar cells gradually diminished during the culture. Isoproterenol when added to the cultured cells failed to stimulate the incorporation of radioactive thymidine or the discharge of the secretory material from the acinar cells.

Animals↗