Search PubMed⌕ Search

Biomedical subjects

N Oya

Publications and source records attributed to N Oya.

At least 19 recordsLinked to original sources
PubMed1992

Radiosensitization efficacy of KU-2285, RP-170 and etanidazole at low radiation doses: assessment by in vitro cytokinesis-block micronucleus assay.

Since the cytokinesis-block micronucleus assay is very sensitive at low radiation doses, we used it to investigate the in vitro sensitizing effects of two new hypoxic cell sensitizers (KU-2285, a fluorinated 2-nitroimidazole and RP-170, a 2-nitroimidazole nucleoside analogue) at 1-3 Gy in comparison with etanidazole. Exponentially growing EMT6 cells were treated with the drugs under aerobic or hypoxic conditions for 40 min prior to and during irradiation, after which the drugs were removed and cytochalasin B (2 micrograms/ml) was added to the medium. The number of micronuclei in binucleate cells was counted after 42 h of culture. Under aerobic conditions the three compounds at 5 mM had no sensitizing effect. Under hypoxic conditions the sensitizer enhancement ratio (SER) at 5 mM was 3.8 for KU-2285, 3.2 for RP-170, and 2.3 for etanidazole, while the oxygen enhancement ratio was 2.9. When the cells were pretreated under hypoxic conditions with drugs at 5 mM but then irradiated under aerobic conditions, KU-2285 and RP-170 had a sensitizing effect whereas etanidazole did not. The sensitizers were also tested at 0.5 and 1 mM, and the SER values were compared with those obtained at high doses (15-30 Gy) using a colony assay. The SER at low doses was higher than that at high doses for 1 and 5 mM KU-2285 and 5 mM RP-170, while the SERs were similar for all concentrations of etanidazole and the lower concentrations of KU-2285 and RP-170. These results might suggest the potential usefulness of KU-2285 and RP-170 in clinical radiotherapy.

Animals↗
PubMed1992

Pharmacokinetics of fluorinated 2-nitroimidazole hypoxic cell radiosensitizers in murine peripheral nervous tissue.

We have previously reported that KU-2285, a 2-nitroimidazole with a fluorinated N1-substituent (-CH2-CF2CONH(CH2)nOH, n = 2), was a promising hypoxic cell radiosensitizer. In this study the pharmacokinetics of KU-2285 and its related compounds (n = 3 and n = 4) were compared with those of etanidazole (a 2-nitroimidazole with an N1-substituent of -CH2CONH(CH2)nOH, n = 2) and its related compounds (n = 3 and n = 4) to assess the effects of incorporation of a CF2 group. The lipophilicity of the fluorinated compounds was higher than that of etanidazole, as measured by the octanol/water partition coefficient. As the number of CH2 groups increased, the lipophilicity of the compounds in both the KU-2285 and etanidazole series increased. The brain tissue levels of the fluorinated compounds were as low as those of the etanidazole derivatives, while the biological half-lives of the fluorinated compounds in peripheral nervous tissues were shorter than those of related non-fluorinated compounds.

Animals↗
PubMed1991

A new single base substitution in a Japanese phenylketonuria (PKU) patient.

DNA analysis on phenylalanine hydroxylase (PAH) gene was performed in four Japanese PKU patients. By the Southern analysis, three patients were confirmed to be homozygous for haplotype 4, and the other one was homozygous for haplotype 2. Sequence analysis on the mutant PAH gene of this haplotype 2 patient, who was born to first-cousin parents, disclosed it to be a C-to-T transition in exon 7. This transition causes the substitution of Arg261 codon to a termination codon.

Base Sequence↗
PubMed1983

Synaptic changes in Purkinje cell dentritic spine of mouse cerebellum after neonatal administration of cytosine arabinoside.

This study was undertaken to elucidate morphological changes in the synaptic area of the Purkinje cell dendritic spines when granule cells were decreased in number. The mice were injected s.c. with 30 mg/kg b.w. of cytosine arabinoside on days 2, 3, and 4, and on days 7, 8 and 9, and were designated as group I and group II, respectively. The mice injected with saline on days 2, 3, and 4 served as control. The cerebella of the mice in each group were examined by electron microscopy on days 30, 60, and 90. Using photographs thus obtained, the synaptic length and area of Purkinje cell dendritic spines which participated in synapses with axons of granule cells were measured by computer. In the controls, these spines did not increase significantly either in synaptic length or in spine area in the duration from 30 to 90 days after birth. In the 90-day-old mice belonging to group I and group II, however, they increased by about 20% in the synaptic length and by about 35% in the spine area as compared to those in age-matched control. The elongation and enlargement show that the synaptic surface on the spine spreads to compensate for synapses lost by reduction in number of granule cells in experimental groups.

Age Factors↗
PubMed1983

Neonatal monosodium glutamate-induced lesions of hypothalamus increase intestinal fat absorption in adult mice.

The hypothalamic lesion induced by monosodium glutamate injection during the suckling period affected the absorption of fat from the intestine. Mice in group 1, in which the hypothalamic lesion included not only the arcuate nucleus, but also the basal preoptic area and two-thirds of the ventromedial nucleus, showed more efficient rates of fat absorption with high serum concentrations of immunoreactive insulin than the control. Mice in group 2, in which the hypothalamic lesion was confined mostly to the arcuate nucleus, also showed a significant increase in fat absorption, but elevated immunoreactive insulin was not found in the serum of these mice.

Aging↗
PubMed1983

Effects of excess amounts of synthetic amino acid preparations on hypothalamus of mice and kittens.

The relationship between the neurotoxicity caused by excess amounts of synthetic amino acid preparations and serum levels of a certain amino acid was examined using suckling mice and kittens. Three preparations, two of which contained aspartic acid and glutamic acid, were injected intraperitoneally into neonatal mice. Almost all the animals which were treated with the preparations containing aspartic acid and glutamic acid at a dosage of more than 40 microliters/g body weight (b.w.) showed hypothalamic lesions. The severity of these increased according to each dose increment. On the other hand, none of the animals treated with the preparation containing neither aspartic acid nor glutamic acid sustained hypothalamic lesions. All kittens injected intravenously with the preparation containing aspartic acid and glutamic acid at dosages of more than 20 microliters/g b.w. also showed hypothalamic lesions, but none of the kittens treated with dosages of less than 10 microliters/g b.w. did. Serum levels of each amino acid reached their highest values as early as 5 min after injection and then returned abruptly to the control value within 3 h.

Amino Acids↗
PubMed1979

Muscular form of glycogenosis type II (Pompe's disease).

An 11-year-old boy who was previously thought to have progressive muscular dystrophy was studied clinically, biochemically, and histologically. He was seen initially with an amyotonic syndrome with no clinical evidence of heart disease. Light and histochemical examination showed vacuolar degeneration and abnormal accumulation of glycogen in the muscular fibers. Electron microscopy showed aggregates of glycogen granules surrounded by a well-defined membrane, as in previously reported cases of type II glycogenosis. Enzymatic study disclosed that acid alpha-glucosidase was deficient in muscle, liver, and heart tissue, although neutral alpha-glucosidase was present within normal ranges. Measurement of acid and neutral alpha-glucosidase activity in muscle from the patient and his sisters and in urine from them and their parents indicated that his sisters are heterozygotes and his parents probably are heterozygotes. The disease was transmitted as an autosomal-recessive trait.

Child↗
PubMed1977

Properties of the alpha-glucosidase from various human tissues in relation to glycogenosis type II (Pompe's disease).

The physico-chemical and electrophoretical properties of alpha-glucosidases from various human tissues and urine have been studied. There were some differences among Peak I enzymes (neutral alpha-glucosidases) obtained from liver, heart, muscle, kidney and urine. These differences are based on different effects of tris(hydroxymethyl)aminomethane and various thermostabilities of the Peak I enzymes. Electrophoretically, the Peak I enzyme activity at pH 6.5 from control tissues displayed a two-banded pattern except in kidney and urine. In the patient with the adult form of Pompe's disease the faster band of the Peak I enzyme from heart and muscle was not found and the slower band of the Peak I enzyme from liver was more cathodic. The results are discussed in relation to glycogenosis type II (Pompe's disease).

Copper↗