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Biomedical subjects

S Miyata

Publications and source records attributed to S Miyata.

At least 217 records · Page 12Linked to original sources
PubMed1986

A simple procedure for the extraction of the native chromophore of visual pigments: the formaldehyde method.

The chromophore of visual pigments was efficiently extracted in its original isomeric conformation by dichloromethane/hexane in the presence of excess formaldehyde. This new method of extraction (the formaldehyde method) in combination with HPLC is useful for the determination of the chromophore composition of visual pigments. The chromophore isolated by this method is biologically active and can be used for regeneration experiments.

Animals↗
PubMed1986

[Effects of preoperative administration of UFT in gastrointestinal cancer].

UFT, a combination antitumor drug consisting of 1 part Futraful and 4 parts Uracil, was administered preoperatively to 10 patients with gastric cancer, 9 patients with colo-rectal cancer and 1 patient with hepatocellular carcinoma. A pharmacokinetic study was then carried out after oral administration of 600 mg per day of UFT, measuring Uracil, Futraful and 5-FU levels in serum and tumor tissue. Preoperative total doses of UFT for gastric cancer were 3.0-11.4 g, for colo-rectal cancer 3.6-16.8 g and for hepatocellular carcinoma 8.4 g. Side effects, mainly gastrointestinal symptoms, were observed in 3 cases. Abnormalities of liver function test, depression of serum protein and bone marrow damage were observed in 4 cases. 5-FU concentration in the tumor tissue was higher than 0.05 mu/g in 15 of 19 patients (79%). This suggested that 5-FU was maintained in the tumor tissue for a longer period. However, it also suggested that the concentration of Uracil in the tumor tissue corresponded to the total dose of UFT as did the degree of side effects.

Adult↗
PubMed1986

A radiopharmaceutical for pancreatic exocrine functional diagnosis: 62Zn-EDDA metabolism in pancreas.

The metabolic pathway of radioactive 62Zn-EDDA (ethylenediamine-N,N'-diacetic acid), in the exocrine pancreas was studied with respect to that of endogenous Zn. In pancreatic duct cannulated dog, the secretion of intravenously injected exogenous 62Zn into pancreatic juice increased under the stimulation of CCK-PZ (pancreatic protein secretion stimulating hormone), which closely correlated to endogenous Zn. Moreover, in pancreatic juice, 62Zn as well as endogenous Zn was selectively bound to Zn-metalloenzymes, carboxypeptidase A and B. These results demonstrated the close correlation between the endogenous and the exogenously-administered Zn (62Zn-EDDA), as well as the high availability of 62Zn-EDDA as a marker of pancreatic function for the follow up of carboxypeptidase metabolism.

Animals↗
PubMed1985

Spatial distribution of visual pigment and dopamine in the bullfrog retina.

Visual pigments and a neurotransmitter, dopamine, were quantitatively investigated in the retina of adult bullfrog, Rana catesbeiana. The adult bullfrog (body length 15-16 cm, body weight 375 +/- 52 g, n = 10) had 21.4 +/- 4.2 nmol visual pigment and 209 +/- 28 pmol dopamine in retinal areas of 266 +/- 27 mm2. Greater pigment densities were recorded in a semicircular band around the optic disc, extending to the nasal and temporal peripheries of the ventral retina. The area with the highest concentration of visual pigment was found in the middle of the dorsal retina, 3-4 mm dorsal to the optic disc. A high concentration of vitamin A2-based pigment was found in the dorsal quarter of the retina (porphyropsin zone); the zone extended up to the most ventral part along peripheral regions of the retina. There was also a band with higher dopamine concentrations although it was not so prominent as that of the visual pigment; the highest concentration of dopamine was found in the area immediately dorsotemporal to the optic disc. Fluorescence micrography indicated that the distribution pattern of catecholamine-containing amacrine cells paralleled that of the dopamine content. The topographic map of dopamine was slightly different from that of visual pigment in the bullfrog retina.

Animals↗
PubMed1985

Heavy metal concentrations in blood cells in patients with amyotrophic lateral sclerosis.

Manganese (Mn) and selenium (Se) concentrations in blood cells were measured by neutron activation analysis. Blood was obtained from patients with amyotrophic lateral sclerosis (ALS), patients with other neurological diseases and control subjects. Dried blood cells were activated by neutron irradiation. Mn was determined after chemical separation and Se was determined nondestructively. Mn concentrations in blood cells from ALS patients were significantly lower (P less than 0.01) than those from the other groups. The Mn concentrations were also significantly lower (P less than 0.01) in late than in earlier stages of ALS. Se concentrations in blood cells from ALS patients were significantly higher (P less than 0.01) than those from the other two groups. A generalized abnormal distribution of these metals may play a role in the pathogenesis of this disorder. Bromine, zinc, rubidium, and iron concentrations of erythrocytes were the same in all groups.

Amyotrophic Lateral Sclerosis↗
PubMed1985

Competition between retinal and 3-dehydroretinal for opsin in the regeneration of visual pigment.

Rhodopsin regenerated faster than porphyropsin in all preparations of bullfrog opsin, bullfrog rod outer segment membrane and cattle opsin. When opsin was incubated with excess amount of an equimolar mixture of 11-cis-retinal and 11-cis-3-dehydroretinal, the composition of the regenerated pigment was simply dependent on the ratio of regeneration rates of rhodopsin and porphyropsin. This result can provide a mechanism to account for the discrepancy in vitamin A1/A2 composition between the retina and the pigment epithelium. The property of opsin preferring retinal to 3-dehydroretinal may be one of the basic factors affecting vitamin A1/A2 visual pigment systems.

Animals↗
PubMed1985

Differences of proteins in isolated egg surface after fertilization of Xenopus laevis.

Egg surface proteins of Xenopus laevis were compared between unfertilized and fertilized egg surfaces before the first cleavage. The egg surfaces were isolated in acetone. The macromolecular compositions of egg surfaces were analyzed by two-dimensional gel electrophoresis and were shown to contain at least 30 proteins with molecular weights ranging from 27,000 to 200,000. At 50 min after fertilization, one spot with a molecular weight of 160,000 disappeared and two bands with molecular weights of 190,000 and 180,000 increased gradually after fertilization. Although the disappearance of the spot was not affected by colchicine or cytochalasin B, intensification of the two bands was inhibited completely by the two agents.

Acetone↗
PubMed1985

Timing of the initiation of rRNA gene expression and nucleolar formation in cleavage embryos arrested by cytochalasin B and podophyllotoxin and in cytoplasm-extracted embryos of Xenopus laevis.

The timing mechanism of rRNA gene expression was studied in Xenopus laevis embryos whose cleavage was arrested by treatment with cytochalasin B or podophyllotoxin, and in fertilized eggs from which about 40% of the cytoplasm was extracted by micromanipulation. rRNA synthesis was activated in the cleavage-arrested embryos and also in cytoplasm-extracted embryos at the time when the control embryos commenced synthesizing rRNA at the late blastula stage. Formation of the nucleolar structure occurred at the normal time in the nuclei of cleavage embryos arrested by podophyllotoxin. Therefore, neither twelve continuous cell divisions nor the nuclear division which normally precedes the MBT (mid-blastula transition) was the factor determining the timing of rDNA expression. Moreover, lowering of the cytoplasmic:nuclear ratio to a certain threshold level was not a prerequisite for rDNA activation. Some regulatory mechanism dependent on the time elapsed from fertilization is likely to be the important factor permitting rDNA expression.

Animals↗
PubMed1985

Formation of ester forms of riboflavin in the pituitary gland of rat.

We studied the formation of ester forms of riboflavin in the pituitary gland of rats using 14C-riboflavin labeling and a gel filtration technique. The active formation of ester fraction of riboflavin suggests that two synthesizing enzymes of ester forms, flavokinase and FAD pyrophosphorylase, exist in this organ. A minor peak containing a lesser amount of radioactivity contained protein as measured by UV absorption at 280 nm was found when supernatant from incubated homogenate was chromatographed on a Sephadex G-15 column. This suggests the presence of a riboflavin-binding protein; the amount of 14C-riboflavin bound to pituitary proteins was expressed as the binding capacity of riboflavin. No changes were found in the binding capacity or esterification of riboflavin in the pituitary gland of rats treated with ACTH, dexamethasone phosphate, or subjected to liver impairment by CC14 injection. However, esterification was increased at 24 and 48 h after adrenalectomy. We posit that the riboflavin turnover in the pituitary gland may not be subject to marked changes in order to maintain the function of this organ. In aged rats, esterification was lower than in young rats suggesting that the turnover of pituitary riboflavin is related to senescent phenomena.

Adrenalectomy↗
PubMed1984

Dopamine-beta-hydroxylase activities in serum and cerebrospinal fluid of aged and demented patients.

Age-related changes in dopamine-beta-hydroxylase (DBH) activities in serum and cerebrospinal fluid (CSF) were determined. In normal subjects, serum DBH activity increased gradually from the 3rd to the 8th decade, but decreased prominently in the 9th decade. DBH activity in CSF did not differ between younger and older subjects. Serum DBH activity decreased significantly in senile dementia of Alzheimer's type (SDAT, 12.2 +/- 8.8 nmoles/min/ml, P less than 0.05), but not in multi-infarct dementia (MID, 13.9 +/- 9.1 nmoles/min/ml) compared to control subjects (17.1 +/- 9.5 nmoles/min/ml). The decrease of serum DBH in SDAT was more prominent in patients with severe dementia and/or severe brain atrophy. DBH activity in CSF was much lower than that in serum and did not correlate with each other. DBH activity in CSF obtained from SDAT patients (1.60 +/- 0.94 nmoles/h/ml) and from MID patients 2.01 +/- 0.99 nmoles/h/ml) were both lower than that from other neurological diseases without dementia (4.04 +/- 3.81 nmoles/h/ml). DBH in CSF from SDAT patients was significantly lower (P less than 0.05) than that from controls, but that from MID did not differ from controls. Noradrenergic nervous dysfunction is partly associated with pathophysiology and life expectancy of senile dementia of Alzheimer's type (SDAT).

Adult↗