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Biomedical subjects

T Oku

Publications and source records attributed to T Oku.

At least 217 records · Page 12Linked to original sources
PubMed1980

Inhibition of beta-sitosterol on intestinal cholesterol absorption in rat using in vivo dual isotope ratio method.

The inhibitory effects of beta-sitosterol on intestinal cholesterol absorption were studied by means of a dual isotope plasma ratio method (in vivo), which is a new technique for the measurement of cholesterol absorption, as well as a ligated-loop method (in situ). The results obtained were as follows: 1. The absorption of beta-sitosterol itself was significantly less than cholesterol. Cholesterol was selectively absorbed from rat intestine. 2. When 100 to 1,000 microgram of beta-sitosterol were added to the dose solution containing 10 microgram of cholesterol, cholesterol absorption by the in vivo experiment decreased with the increae of additional beta-sitosterol. 3. A similar inhibitory effect of beta-sitosterol was observed by the in situ ligated-loop method. These results suggest that beta-sitosterol actually inhibits cholesterol absorption in the physiological state of an animal.

Animals↗
PubMed1976

Light-dependent development of thermoluminescence, delayed emission and fluorescence variation in dark-grown spruce leaves.

Thermoluminescence profiles of spruce leaves grown under various light or dark conditions were measured after excitation at a low temperature (-70 to -20 degrees C) by 1-min illumination with red light, and the following results were obtained. Mature spruce leaves showed five thermoluminescence bands at -30, -5, +20, +40 (or +35) and +70 degrees C (denoted as Zv, A, B1, B2 and C bands, respectively), but dark-grown spruce leaves with a similar chlorophyll content showed only two bands, at -30 and +70 degrees C (the Zv and C bands) and were devoid of the three other bands (the A, B1, and B2 bands). On exposure of the dark-grown leaves to continuous red light, the A, B1and B2 bands were rapidly developed, and the development was accompanied by enhancement of delayed emission, fluorescence variation and the Hill activity (photoreduction of 2,6-dichlorophenolindophenol with water as electron donor). It was demonstrated that the dark-grown spruce leaves are devoid of the water-splitting system in Photosystem II, and that the latent water-splitting activity is rapidly photoactivated by exposure of the leaves to continuous red light. These results on the gymnosperm spruce leaves, in which greening proceeds in complete darkness, being independent of the development of the water-splitting system in light, were discussed in relation to previous observations on angiosperm leaves, in which both greening and the activity generation proceed in the light.

Chlorophyll↗
PubMed1976

Multiple-flash development of thermoluminescence bands in dark-grown spruce leaves.

Spruce leaves greened in darkness were devoid of three of the five thermoluminescence bands found for mature leaves. These bands were developed rapidly by exposure of the dark-grown leaves to continuous light. The development of these bands was studied by illumination with repetitive flashes at varied intervals. Flashes at intervals of 1 s were the most effective in inducing these bands. Those at shorter or longer intervals were less effective. It was deduced from these data that the development of these bands is a multiquantum process which involves at least two photo-events with a dark reaction between them.

Chloroplasts↗
PubMed1976

Development of 1,25-dihydroxycholecalciferol receptor in the duodenal cytosol of chick embryo.

The development of 1,25-(OH)2D3 receptor in the duodenal cytosol of chick embryo was studied by the sucrose density gradient analysis. The binding profile for 1,25-(OH)2D3 in the cytosol of vitamin D-deficient chick duodenum on the sucrose density gradient revealed 3 binding components, and the sedimentation constant was estimated as 2.5, 3.5 and 5.5S respectively. The 3.5S binding component has high affinity and low capacity for 1,25-(OH)2D3 and is thought to be 1,25-(OH)2D3 receptor. During the development of chick embryo, the 3.5S binding component was not detected in 13-day embryonic duodenum, it appeared on 15th day of incubation and then gradually increased to the level of vitamin D-deficient chick on 19th day of incubation. The 5.5S binding component was specific for 25-OH-D3 and it was found even in 13-day embryo, but it did not show any significant change during development. On the other hand, the 2.5S component was not specific for either 1,25-(OH)2D3 or 25-OH-D3. However, it was main binding component in early stages of development and decreased during development. From these results, it is suggested that the receptor for 1,25-(OH)2D3 is available a few days before hatching and the inability to produce CaBP in the duodenum of chick embryo could not be ascribed to the absence of the receptor.

Animals↗