Search PubMed⌕ Search

Biomedical subjects

K Hosoya

Publications and source records attributed to K Hosoya.

64 records · Page 4Linked to original sources
PubMed1985

Effect of the absorption enhancer, Azone, on the transport of 5-fluorouracil across hairless rat skin.

The effect of the percutaneous absorption enhancer, Azone, on the transport of 5-fluorouracil across hairless rat skin has been investigated by an in-vitro permeation technique using 2-chamber diffusion cells. Azone (3% w/v) emulsions were used. Azone enhanced the permeability of drug 10-100 times across the full-thickness skin although there was a lag time about 10 h. The long lag time, however, disappeared with Azone pretreatment. Azone also affected the transport across stripped skin. These results suggest that Azone mainly affects the stratum corneum. It seems to change the diffusivity of drug in that layer and is not so effective against diffusivities in the epidermis and dermis.

Animals↗
PubMed1984

Studies on algal cytochromes. V. Purification and characterization of cytochrome c-552 from a red alga, Polysiphonia urceolata.

Cytochrome c-552 was extracted from a red alga, Polysiphonia urceolata, by immersion of the frozen trichomes in deionized water. Purification was carried out by acrinol treatment, ammonium sulfate fractionation, DEAE-Sephacel chromatography, hydroxyapatite column chromatography, and Bio-Gel P-10 gel filtration. The ferrocytochrome c-552 has absorption maxima at 551.5(alpha), 522.5(beta), 416.3(gamma), 318(delta), 292, and 270 nm; those of the ferricytochrome are at 525, 408.5(gamma), and 358 nm. The pyridine ferrohemochrome showed absorption maxima at 550(alpha), 520(beta), and 414 nm(gamma). The alpha-band of the ferrocytochrome is symmetric without any shoulder at room temperature, and does not split even at liquid nitrogen temperature. The ferricytochrome showed a weak absorption shoulder at 695 nm, suggesting a methionine sulfur to be the sixth ligand of heme c iron. The cytochrome is oxidized by ferricyanide and reduced by ferrocyanide, cysteine, ascorbate, and hydrosulfite. Autoxidation was not observed. The midpoint potential (Em) of the cytochrome was determined by equilibration with the ferro- and ferricyanide system to be 0.333 volt at pH 7.0 and 25 degrees C. The isoelectric points of the ferro- and ferricytochromes were determined to be at pH 3.85 and 4.02, respectively, by the isoelectric focusing method. The molecular weight was estimated to be about 12,000 from the results of gel filtration and SDS polyacrylamide gel electrophoresis.

Cytochrome c Group↗
PubMed1984

Antitumor agent poly (amino acid) conjugates as a drug carrier in cancer chemotherapy.

Antitumor agent melphalan was conjugated through a carbodiimide-catalyzed reaction to poly (L-lysine) (71.3K and 2K) and poly (L-glutamic acid) (60K and 14K) at a ratio of approximately one molecule per 7-lysyl and 23-glutamate residues, respectively. These conjugates had 40-70% of alkylating activities by themselves in vitro as compared with free melphalan. Poly (glutamic acid) conjugates showed the antitumor activity in vivo against Yoshida sarcoma in rats. In addition, poly (glutamic acid) conjugates containing 3H-phenylalanine which was used as a model compound instead of melphalan had a sustained release property of radioactivity and the release rates could be regulated by exopeptidases. After subcutaneous injection as the first choice of routes of administration, moreover, the conjugates were found to be absorbed through the lymphatic transport system, probably due to the macromolecularity. These results suggest that the melphalan-poly (amino acid) conjugates are one of good candidates to attain the sustained release and targeting of drugs in cancer chemotherapy.

Absorption↗
PubMed1976

The effect of p-chlorophenylalanine on the pethidine- or methadone-induced decrease in locomotor activity of rats.

Either pethidine HCl (50 mg/kg s.c.) or methadone HCl (8 mg/kg s.c.) produced a prominent decrease in locomotor activity of rats. Pretreatment of rats with p-chlorophenylalanine (p-CPA, 320 mg/kg i.p.) 48 h before the narcotic injection significantly antagonized the activity-decreasing effects of narcotics. When rats pretreated with p-CPA were given 5-hydroxytryptophan (75 mg/kg s.c.) 30 min before narcotic administration, the activity-decreasing response to narcotics was restored. Thus, a decrease in locomotor activity induced in rats by either pethidine or methadone is probably mediated by serotonergic mechanisms.

Animals↗
PubMedDate not supplied

Masculinization mechanism of hybrids in bitterlings (Teleostei: Cyprinidae).

The sex ratio of bitterling hybrids (subfamily: Acheilognathinae) is often likely to be biased toward males. Artificial hybridization was carried out in 10 species of bitterlings (three genera) in order to elucidate the masculinization mechanism of hybrids. Tanakia himantegus never produced viable F1 hybrids with other species, while hybrids of most other species were viable. In terms of sex ratio and fertility, hybrids were clearly divided into two groups: congeneric Tanakia hybrids and others. Both male and female congeneric Tanakia hybrids were fertile. The sex ratio was nearly 1:1 in all groups of Tanakia hybrids. Except for the congeneric Tanakia hybrids, sterile males appeared predominantly in groups of hybrids in which females were very rare but remained fertile. Sterile intersexes were also observed in five hybrid groups: T. lanceolata (female) x Acheilognathus cyanostigma (male), Rhodeus uyekii (female) x T. lanceolata (male), A. rhombeus (female) x T. lanceolata (male), A. rhombeus (female) x T. limbata (male), and A. tabira tabira (female) x A. cyanostigma (male). In the development of male-predominant hybrids, although hybrid and control (parental species) hatching and survival rates do not differ, no females appeared in hybrids, contrary to the controls. Taking the female heterogametic sex-determining system (ZW) and the phylogenetic relationship of bitterlings into consideration, the masculinization mechanism of hybrids in bitterlings can be explained by the interaction of two sex chromosomes, derived from each parental species. The basic genetic sex in bitterlings is male (ZZ) and the derivative is female (ZW). When parental species are related, the sex phenotype of hybrids coincides with the genetic sex. However, when the parental species differ, the sex phenotype of the ZW genotype is reversed to become male by an abnormal interaction between the Z and W chromosomes. The rare appearance of females and intersexes in male-predominant hybrids might be due to complete or partial functional expression of the W chromosome.

Animals↗