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Biomedical subjects

Y Asaka

Publications and source records attributed to Y Asaka.

29 records · Page 2Linked to original sources
PubMed1992

Postnatal changes in sublobular distribution of NADPH-cytochrome P-450 reductase in rat liver.

Immunohistochemical distribution of NADPH-cytochrome P-450 reductase (NADPH-ferrihaemoprotein reductase; EC 1.6.2.4.) in the liver lobule was examined during development of the rat. From the 19th day of gestation to 4 days after birth, the enzyme was distributed uniformly throughout the lobule. The immunostaining for the enzyme was weak before birth, and became slightly stronger after birth. A slightly uneven distribution of immunoreactivity, stronger in perivenular zones, appeared at 5 days after birth. Then, the staining intensity in perivenular zones became progressively stronger with age, except for a slight increase between 10 and 20 days of age. The intensity in periportal zones also increased gradually, although it remained weaker than that in perivenular zones. Around 30 days of age, the distribution of the immunostaining, stronger in perivenular than in periportal zones, was similar to that seen in the lobules of adult animals. Thus, heterogeneity among hepatocytes with respect to the enzyme content is not present in fetal and newborn rats but develops gradually during postnatal development; the postnatal growth of the liver is accompanied by a change in the pattern of the distribution of this enzyme within the lobule.

Age Factors↗
PubMed1992

Relation between cytochrome P-450 increase and endoplasmic reticulum proliferation in hepatocytes of mice treated with phenobarbital: a microphotometric and morphometric study.

To obtain detailed information on phenobarbital (PB)-induced cytochrome P-450 (P-450) increase and endoplasmic reticulum (ER) proliferation in hepatocytes, we estimated microphotometrically the amount of P-450 per unit cytoplasmic volume and morphometrically the area of ER per unit cytoplasmic volume in hepatocytes adjacent to the portal area or central venule (1 periportal or 1 perivenular cells) and in the second and third layers from the portal area or central venule (2, 3 periportal or 2, 3 perivenular cells) from mice injected with 35, 50, 100, or 150 mg/kg PB once a day for 3 days. By dividing the P-450 amount by the ER area, the number of P-450 molecules per unit ER area was also calculated. In 1 and 2, 3 perivenular cells, except for 2, 3 perivenular cells after injection of 150 mg/kg PB, the amount of P-450 increased with ER proliferation and the number of P-450 molecules in ER remained unchanged after injection of 50, 100, or 150 mg/kg PB. In 2, 3 periportal cells, however, the P-450 amount and the number of P-450 molecules in ER increased markedly without or with some ER proliferation after injection of 50, 100, or 150 mg/kg PB; the P-450 increase appears to be generally independent of ER proliferation. The 1 periportal cells are probably exceptional hepatocytes that usually did not respond to PB stimulation.

Animals↗
PubMed1991

High glucose-6-phosphatase activity in non-pigmented epithelial cells of rabbit ciliary body.

For study of the origin of glucose in the aqueous humor, glucose-6-phosphatase (G6Pase) and hexokinase activities, and glycogen, were cytochemically examined in the ciliary body (CB) of rabbit. G6Pase activity was also assayed biochemically. The staining reaction for G6Pase activity was strong in the non-pigmented epithelium (NPE) in the pars plana and tips of ciliary processes in the region containing large ciliary pockets within the pars plicata. NPE cells contained abundant reaction product for G6Pase activity in the endoplasmic reticulum (ER) and nuclear envelope. However, NPE in other regions of the CB and pigmented epithelium (PE) of CB, and other areas surrounding the anterior and (PE) of CB, and other areas surrounding the anterior and posterior chambers, showed weak or no G6Pase staining reaction. Biochemical G6Pase activity in the whole ciliary body was relatively high. Both NPE and PE in the pars plana and the tips showed strong staining reaction for hexokinase activity but no staining for glycogen. Furthermore, NPE cells in the tips bore large aggregates of smooth ER and many Golgi apparati. These suggest that the high G6Pase activity in NPE cells in the pars plana and the tips is related to glucose release into the aqueous humor.

Animals↗
PubMed1988

Inhibitory effect of phenobarbital on peroxisome biogenesis in mouse hepatocytes.

Peroxisomes in hepatocytes from mice administered 35, 50, or 100 mg/kg of phenobarbital (PB) were analyzed by quantitative electron microscopy. In perivenular hepatocytes, the volume of peroxisomes per unit cytoplasmic volume decreased to 78 or 57% of that of control animals by administration of 50 or 100 mg/kg. Their average volume also decreased to 78 or 64% of that in control animals in animals injected with 35 or 50 mg/kg. Further, cytochemical catalase activity appeared decreased in peroxisomes of hepatocytes of this zone after administration of 50 or 100 mg/kg. These suggest an inhibitory action of PB administration of biogenesis of peroxisomes in perivenular hepatocytes. In periportal hepatocytes, however, the volume density, average volume, and cytochemical catalase activity of peroxisomes did not change by administration of any doses of PB. Thus, PB administration appears to produce no inhibitory effect on the peroxisome biogenesis in periportal hepatocytes. On the other hand, the number of peroxisomes per unit cytoplasmic volume increased in both periportal and perivenular hepatocytes in animals injected with 50 mg/kg, although it returned to the level of control animals by injection of 100 mg/kg. The inhibitory effect of PB on the peroxisome neogenesis in perivenular hepatocytes may be related to the marked smooth endoplasmic reticulum proliferation by administration of this drug.

Animals↗
PubMed1988

Prediction of curve progression in idiopathic scoliosis based on initial roentgenograms. A proposal of an equation.

A retrospective study was conducted in 122 patients with idiopathic scoliosis who were followed for more than 2 years. There were 58 patients who showed 5 degrees (Cobb) or more progression, and 41 patients who showed no progression. Only those who did not receive any treatment or who failed to comply with brace treatment were selected, to eliminate the effect of treatment. In the early phase of the study, 12 parameters were put into a multivariate analysis to observe the relative weight of each of them, which led the authors to eliminate the following five parameters: 1) Cobb angle, 2) rotation of the apical vertebra, 3) deviation of the apical vertebra, 4) Risser's expected correction: (standing angle--supine angle) X 3, and 5) maturation index of the iliac apophysis. Through a multiple regression analysis, an equation was obtained to correlate the predictive and the real progression within 10 degrees deviation.

Child↗
PubMed1986

[Follow-up results of brace treatment of adolescent idiopathic scoliosis].

Assessment of brace treatment for idiopathic scoliosis should be based on long-term follow-up results compared with those in untreated cases. Such comparison, however, is extremely difficult from an ethical standpoint. Therefore, we conducted a comparable follow-up study on three groups of patients divided according to how well the brace had been worn during the period of treatment. Two hundred and twenty-six adolescent idiopathic cases in which brace treatment had been initiated before skeletal maturity were studied, 170 of which were followed up after the termination of the treatment. In 131 single curve cases, those who had worn the brace well showed significantly less progression than those who had worn it poorly, while 38 double curve cases failed to show significant difference between the two groups. Approximately two thirds of the cases demonstrated no major progression whether the brace had been worn well or not. Development of a method to select cases based on prediction of curve progression is an important project in the near future.

Adolescent↗
PubMed1979

[Idiopathic scoliosis and equilibrium disturbance (author's transl)].

UNLABELLED: The body balance is maintained by the complexed nervous system in the brain stem and the cerebellum. However, the amount of neurological information obtained from this area is relatively small, so that a fine abnormality is easily overlooked or could not be definitely elicited. Examination of the ocular movement becomes often a powerful tool to detect an indiscrete lesion in the brain stem and the cerebellum which otherwise fails to be demonstrated neurologically. METHOD: With a hypothesis that equilibrium disturbance might be playing a role in the development of idiopathic scoliosis, extensive neuro-otological studies were carried out in three groups of individuals: 169 cases of idiopathic scoliosis, 19 cases of congenital scoliosis and 488 young girls with no scoliosis. The examination included Mann's test, deviation tests and other neuro-otological tests with the special reference to the observation of the ocular movement. RESULTS: 1. There was no case in the entire groups which presented positive Mann's test or deviation abnormality. 2. With the aid of electronystagmography (ENG), the presence of nystagmus was detected in 71 out of 169 cases (42.0%) with idiopathic scoliosis, 9 out of 19 cases (46.7%) with congenital scoliosis and 5 out of 488 girls (1.0%) with no scoliosis. This fact was highly suggestive of the possibility of equilibrium disturbance in the background of scoliosis. 3. However, even with positive ENG findings, few cases showed abnormality on optokinetic nystagmus (OKN) test or eye tracking test, so that definite localization of the lesion was impossible in the majority of the cases with the abnormal ocular movement. 4. There was no significant correlation between the rate of the abnormal ocular movement and the age of the patient, the magnitude of the spinal curve or the curve pattern. CONCLUSION: The co-existence of abnormal ocular movement and scoliosis was proved to be statistically significant, suggesting that equilibrium disturbance might be playing a role in the multifactorial etiology of idiopathic scoliosis, although the real pathomechanism still remains to be studied.

Adolescent↗