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Biomedical subjects

Y Fukui

Publications and source records attributed to Y Fukui.

At least 415 records · Page 23Linked to original sources
PubMed1988

Ram-specific effects on in-vitro fertilization and cleavage of sheep oocytes matured in vitro.

The present experiments were designed to identify possible male-specific effects on early embryonic development in vitro: Sheep oocytes were matured in vitro for 24-26 h and then fertilized in vitro using equal numbers of viable spermatozoa from 1 of 6 Clun Forest rams. At 15-18 h after insemination, oocytes were either fixed and examined for fertilization and polyspermy or further cultured in modified M 199 medium for 3 days in an oviduct epithelial co-culture system. There were significant differences in 5 separate trials between the rams with respect to the rate of fertilization, degree of polyspermy and cleavage rate after monospermic fertilization. The mean rate of fertilization varied from 89% in Ram B to 43% in Ram C while the percentage of polyspermic eggs varied from 5 to 34%. Both the absolute number of embryos cleaving to the 16-cell stage and the calculated percentage of monospermic eggs reaching the 16-cell stage differed markedly between groups of eggs fertilized by different rams. The results indicate that the development of sheep eggs in vitro is differentially affected by the ram from which the spermatozoa are collected.

Animals↗
PubMed1988

Teratogenic interaction of ethanol and hyperthermia in mice.

Alcohol and maternal hyperthermia have been implicated in human birth defects. Both ethanol and heat can induce neural tube defects (NTDs) and other developmental abnormalities in mice when large doses are given during pregnancy. To explore the teratogenic interaction of both agents, pregnant ICR mice were injected with a single dose of 25% ethanol and/or were heat-stressed in a water bath at 42 degrees C on the morning of Day 8 of gestation. Combined treatment with ethanol (0.01-0.02 ml/g) and heat (10 min), when they were given concurrently or 1 hr apart, resulted in a significant increase of resorptions and externally malformed fetuses. Skeletal malformations and visceral variations also increased significantly following a concurrent exposure to both agents. These results indicate that ethanol and heat can be synergistically teratogenic in mice when the doses of each agent are below the teratogenic threshold. It was also suggested that pretreatment with a small dose of ethanol may not enhance the teratogenicity of heat when the hyperthermic stress is strong enough and teratogenic by itself.

Animals↗
PubMed1988

Effects of ethanol on testicular steroidogenesis in the rat.

The effects of ethanol and NAD+ on the pregnenolone-to-testosterone pathway of testicular steroidogenesis in lysed Leydig cell preparations were investigated. Testosterone and four precursor steroids were determined by gas chromatography/mass spectrometry after incubation of the cell preparations with 100 microM of pregnenolone and appropriate concentrations of ethanol (1-100 mM). Concentrations of all 4-ene-steroids measured were significantly decreased even at the lowest concentration of ethanol. When NAD+ (0.1 mM) was added to the incubation medium, the levels of progesterone and 17-hydroxyprogesterone returned to control values, whereas those of androstenedione and testosterone remained decreased. These results suggest that ethanol may inhibit testicular steroidogenesis by suppressing at least two steps in the pregnenolone-to-testosterone pathway, the pregnenolone-to-progesterone step catalysed by NAD+-dependent 5-ene-3 beta-hydroxysteroid dehydrogenase/isomerase and the 17-hydroxy-progesterone-to-androstenedione step catalysed by the NAD+-independent C17-20 lyase.

17-alpha-Hydroxypregnenolone↗
PubMed1987

A systematic regional study of brain salsolinol levels during and immediately following chronic ethanol ingestion in rats.

Regional contents of salsolinol and catecholamines in the brain of normal and ethanol-treated rats were studied. Male Sprague Dawley rats were given ethanol solution as sole drinking fluid for 3, 4, 5 or 6 months. Salsolinol determined by gas chromatography mass spectrometry was found to be present in the hypothalamus and the striatum of control rats. The levels of salsolinol in these regions increased significantly by long-term ethanol drinking and rapidly decreased to control levels following its removal. Salsolinol levels in other regions of rat brain were extremely low or negative and unaltered upon chronic ethanol treatment. In ethanol-treated rats the hypothalamic salsolinol, although generally higher than in the striatum, increased along with the ethanol exposure, whereas the striatal salsolinol was constant during those periods of study. Brain dopamine (DA) and norepinephrine contents remained unaltered during and immediately after chronic ethanol treatments. No correlation of salsolinol levels with DA contents or blood ethanol concentrations was observed. The occurrence of salsolinol in selected areas of rat brain with lack of changes in catecholamine level but as a result of an in vivo formation by long-term ethanol drinking was considered to be due to an alteration of acetaldehyde metabolism in the liver and brain.

Animals↗
PubMed1987

Metabolic interaction between toluene and ethanol in rabbits.

The metabolic interaction of toluene and ethanol was studied in male rabbits having received ethanol (26.0 mmol/kg PO), toluene (5.4 mmol/kg PO) or both. Compared with ethanol alone, toluene given 2 h after ethanol caused a significantly higher and more prolonged concentration of blood alcohol. A similar trend of blood alcohol was observed at the later stage with toluene given prior to ethanol. On the other hand, with simultaneous doses of the two substances, the blood toluene concentration was higher for the first 15-30 min than the ethanol control and the urinary excretion of hippuric acid, a main metabolite of toluene, was markedly decreased for the first 2 h. The blood ethanol in this group, on the contrary, was reduced until 1 h after administration. These results indicate that toluene and ethanol act reciprocally as competitive inhibitors in their metabolism after single administrations.

Animals↗
PubMed1987

Mapping of the ras1 gene of Schizosaccharomyces pombe.

The ras1 gene, an oncogene homologue, is known to be essential for recognition of the mating pheromone and hence for conjugation but not for vegetative growth in Schizosaccharomyces pombe. To facilitate further characterization and genetic manipulation of this gene, we have mapped it by using S. pombe strains which carry the Saccharomyces cerevisiae LEU2 gene inserted next to ras1 on the chromosome. Crosses with tester strains revealed that ras1 is tightly linked to pro2 on chromosome I. Furthermore, we have shown that ras1 is allelic with ste5, one of the sterility genes described by O. Girgsdies. The map position previously reported for ste5 eventually turned out to be false.

Alleles↗
PubMed1987

Developmental abnormalities of mouse cerebellum induced by intracisternal injection of ochratoxin A in neonatal period.

Ochratoxin A, one of the food-contaminating mycotoxins, is known to impair brain development in mammals. Slc:ICR mice were treated intracisternally with a single dose of 5 micrograms ochratoxin A on day 0, 1, 2, 4, 5, or 7 after birth, in order to examine the direct effects of ochratoxin A on cerebellar development. The mice in each group were killed at 30 days of age, and the brains examined by light microscopy. Body and total brain weights were reduced (7 to 15%) in the treated groups. Cerebellar weight was also significantly reduced (18 to 27%) in all treated groups. In mice treated on day 0, 1, or 2, the layered structure of the vermis was well preserved, but some animals treated on day 4, 5, or 7 had cerebella with disarranged cortical structure. The number of folia decreased and the foliation index showed a significant decrease in the groups treated on days 0, 1, and 2.

Animals↗
PubMed1987

The effect of diphenylamine derivatives on arachidonic acid metabolism in rat peritoneal macrophages.

The effect of diphenylamine derivatives such as diclofenac sodium, mefenamic acid and lobenzarit disodium on arachidonic acid metabolism in rat peritoneal macrophages was examined. Lobenzarit disodium has no effect on prostaglandin E2 production as measured by radioimmunoassay although two other diphenylamine derivatives have a potent inhibitory activity. Three diphenylamine derivatives have no effect on Ca2+ ionophore-stimulated release of radioactivity from (3H)arachidonic acid-labeled macrophages. HPLC analysis revealed that lobenzarit disodium had no effect on the synthesis of lipoxygenase products as observed in diclofenac sodium and mefenamic acid. It is concluded that lobenzarit disodium, although its fundamental chemical structure resembles diclofenac sodium and mefenamic acid, has no inhibitory activity on arachidonic acid metabolism, suggesting that immunomodulatory activities of lobenzarit disodium are manifested without interfering with arachidonic acid metabolism.

Aniline Compounds↗
PubMed1987

Placental transfer of ochratoxin A and its cytotoxic effect on the mouse embryonic brain.

Pregnant ICR mice were given a single ip injection of 5 mg ochratoxin A/kg on day 11 or 13 of pregnancy. Concentrations of ochratoxin A in the maternal serum and tissues reached maximum levels within 2 hr of the injection and then decreased rapidly. The half-life of the toxin in serum was 28.7 hr on day 11 and 23.6 hr on day 13. On the other hand, the concentrations of ochratoxin A in the embryos were very low 2 hr after injection and then gradually increased up to 48 and 30 hr after injection on day 11 and 13, respectively. Pharmacokinetically, the embryo was found to be a 'deep' compartment. In mice treated with ochratoxin A on day 10 of pregnancy, the incidence of pyknotic cells in the telencephalon of the embryos began to increase 12 hr after injection to a peak between 36 and 48 hr, coinciding with the time of peak concentration of the toxin in the embryo.

Amniotic Fluid↗
PubMed1987

Derivative spectrophotometric studies on cytotoxic effects of carbon monoxide.

Characteristics of cytochrome oxidase prepared from hearts of Sprague-Dawley male rats were studied with the use of the fourth derivative spectrophotometry in respect to the cytotoxic effects of carbon monoxide (CO). CO-exposed rats tended to show lower specific activities of cytochrome oxidase than control and recovered rats. Moreover, there was a significant difference in the fourth derivative spectral features of the enzyme: CO-exposed groups indicated peaks at 412 nm in the spectra while controls at 408 nm. This spectral difference seemed to reflect specific effect of CO on cytochrome oxidase, though such trace remained for not more than a day after death.

Animals↗
PubMed1987

Agar-overlay immunofluorescence: high-resolution studies of cytoskeletal components and their changes during chemotaxis.

Cells that are flattened by overlaying with a thin sheet of agarose can be instantaneously fixed with freezing absolute methanol containing 1% formalin. This procedure results in good preservation of the cytoskeleton. Use of this technique ("agar-overlay immunofluorescence") clarified that (1) Dictyostelium myosin exists in situ as thick filaments (Yumura and Fukui, 1985), (2) the thick filaments are arranged in a meshwork at the posterior cortex of a polarized cell performing directed locomotion, at the constricting portion of a dividing cell forming a contractile ring, and at the outermost lateral periphery of a cell engaging in spiral aggregation (Fig. 1f; Yumura et al., 1984; Yumura and Fukui, 1985), and (3) the distribution of thick filaments changes dramatically in response to the chemoattractant cAMP in 1 minute (Fig. 3; Yumura and Fukui, 1985). This technique can provide valuable information on the dynamic features as well as the detailed organization of cytoskeletal elements which, otherwise, cannot be visualized with sufficient resolution.

Chemotaxis↗