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Biomedical subjects

M Asahi

Publications and source records attributed to M Asahi.

At least 109 records · Page 6Linked to original sources
PubMed1991

Invasion and survival of Fusarium solani in the dexamethasone-treated cornea of rabbits.

Electron microscopic observations, as well as in vitro experiments, on experimental Fusarium solani keratitis of rabbits were performed to study the mode of fungal invasion into the corneal stroma, the interactions between F. solani and inflammatory cells under the influence of topical dexamethasone (DXM) treatment, and the survival mechanism of the fungi in the DXM-treated cornea. Electron microscopy showed that, while the fungus invaded into the corneal stroma, digestion of collagen fibrils occurred around the hyphae, where amorphous material was often noted. In DXM-nontreated cornea, the fungal hyphae were entrapped by pseudopodia of the neutrophils and destruction of the hyphae was noted on day 3 of infection, most hyphae having disappeared by day 7. In the DXM-treated cornea, however, neutrophils could not ingest and destroy the hyphae. In qualitative nitroblue tetrazolium (NBT)-reduction tests using rabbit peripheral blood neutrophils, DXM significantly suppressed the rate of NBT-reduction and the rate of adherence to the fungal microconidia. In the DXM-treated corneal lesions, a considerable increase in both number and size of fungal peroxisomes was noted. Furthermore, the hyphae, surrounded by neutrophils, showed double or triple cell wall formation or sometimes a hypha-in-hypha structure. Similar hypha-in-hypha structures were also observed when the organisms were treated in vitro with a fungistatic concentration of H2O2. We suggest that this special structure is a protective device produced for the survival of F. solani when subject to neutrophil attack in the DXM-treated cornea.

Animals↗
PubMed1991

[Dermatological findings in the annual examination of the patients with Yusho in 1989-1990].

We reported the skin symptoms of the patients with Yusho in the 1989 and 1990 annual examinations. We also studied the alteration of the skin symptoms in 33 patients followed up for 14 years (1977-1990). Most of these patients showed obvious improvement in their skin symptoms during 12 years (1977-1988). However, a remarkable improvement was not observed in recent 3 years and approximately 40% of the patients still had comedones and/or acneiform eruptions.

Female↗
PubMed1990

Diverse effects of poly-basic amino acids, heparin and ionic strength on the phosphorylation of various substrates by cytosolic protein-tyrosine kinase from porcine spleen.

1. Effects of poly-basic amino acids, heparin and ionic strength on the activity of cytosolic protein-tyrosine kinase from porcine spleen (CPTK-40) have been studied. 2. Both polylysine and polyarginine stimulated the phosphorylation of [Val5]angiotensin II and E11 G1 (synthetic peptide of EDAEYAARRRG), but could neither stimulate nor inhibit the phosphorylation of random copolymers; poly(EY)4:1 and poly(EAY)6:3:1. 3. Heparin stimulated the phosphorylation of poly(EY)4:1 by 2.5-fold, however, it inhibited those of E11G1, poly(EAY)6:3:1, casein and H2B histone. 4. Elevation of ionic strength of either NaCl, KCl or (NH4)2SO4 stimulated the phosphorylation of poly(EY)4:1 by greater than 5-fold, but inhibited those of casein, tubulin, H2B histone, E11G1 and poly(EAY)6:3:1. 5. These effectors did not change the Km for substrates but increased the Vmax. 6. These results suggest that the effects of poly-basic amino acids, heparin and ionic strength on the activity of CPTK-40 are mainly on the substrates employed rather than on the enzyme itself.

Amino Acids↗
PubMed1989

Phospholipids differently modulate the activity of cytosolic protein-tyrosine kinase from porcine spleen.

Effect of membrane phospholipids on the activity of cytosolic protein-tyrosine kinase from porcine spleen (CPTK-40) has been studied. Using poly(Glu Na, Tyr)4:1 as a substrate, phosphatidylethanolamine, phosphatidylcholine and phosphatidylserine had stimulatory effects on that phosphorylation activity, however phosphatidic acid had inhibitory and phosphatidylinositol had no effects. Similar results were obtained using[Val5]angiotensin II as a substrate. On the other hand using basic protein (H2B histone and myelin basic protein) as substrates, phosphatidic acid stimulated the activity of CPTK-40, while phosphatidylinositol inhibited the activity. Phosphatidylethanolamine, phosphatidylcholine and phosphatidylserine caused different effect on the activity of CPTK-40 depending on the substrate employed. However using acidic protein (tubulin and casein) as substrates, the activity of CPTK-40 was neither stimulated nor inhibited by any phospholipids. These results suggest that phospholipids may modulate the activity of CPTK-40.

Animals↗
PubMed1989

Effect of poly-basic amino acids on the phosphorylation of various substrate proteins by cytosolic protein-tyrosine kinase from porcine spleen.

Cytosolic protein-tyrosine kinase from porcine spleen (CPTK-40) is strongly activated by poly-L-lysine using bovine serum albumin, ovalbumin, phosphorylase b, calmodulin and H1 histone as substrate proteins. However, this polyamine inhibited the enzyme activities when myelin basic protein, tubulin and H2B histone were used as substrate proteins. These stimulatory and inhibitory effects on CPTK-40 are not specific for polylysine, but polyarginine and polyornithine have similar effects on this phosphorylation reaction. Effect of poly-basic amino acids on CPTK-40 seems to be mainly on the substrate proteins, rather than on the enzyme itself.

Animals↗
PubMed1989

[Dermatological findings in the annual examination of the patients with yusho in 1987-1988--with special reference to the alteration of the skin symptoms in the patients followed up for 20 years].

We reported on the skin symptoms of the patients with yusho in the 1987 and 1988 annual examinations. We also studied the alteration of the skin symptoms in the patients followed up for 20 years. These patients showed obvious improvement in their skin symptoms during these 20 years. However, about a half of the patients still had comedones and/or acneiform eruptions, although the number of eruptions had decreased. The cases with blood PCB pattern A (typical yusho pattern) demonstrated higher skin severity grading points than those of the other groups (patterns B and C), but even in these cases the skin eruptions had improved.

Female↗
PubMed1989

Hyperplastic cellular components of a hemangiopericytoma. An ultrastructural study.

Based on ultrastructural features of cellular components of a hemangiopericytoma, hyperplastic cells are classifiable into fibroblast-like (group I), endotheloid (group II) and pericyte-like (group III) cells. The transformation of the group I cells to the group II, or to the group III cells, is pronounced in our electron micrographs and this may imply that the group I cell is the principal cell of origin in this neoplasm. The smooth muscle-like (group IV) cells comprising the media of the arteries and veins in this neoplasm may represent modified, possibly de-differentiated smooth muscle cells reacted to the neoplastic proliferation of the surrounding adventitial (group I) cells.

Adult↗
PubMed1985

Purification and characterization of major extracellular proteinases from Trichophyton rubrum.

Two extracellular proteinases that probably play a central role in the metabolism and pathogenesis of the most common dermatophyte of man, Trichophyton rubrum, were purified to homogeneity. Size-exclusion chromatography and Chromatofocusing were used to purify the major proteinases 42-fold from crude fungal culture filtrate. The major enzyme has pI 7.8 and subunit Mr 44 000, but forms a dimer of Mr approx. 90 000 in the absence of reducing agents. A second enzyme with pI 6.5 and subunit Mr 36 000, was also purified. It is very similar in substrate specificity to the major enzyme but has lower specific activity, and may be an autoproteolysis product. The major proteinase has pH optimum 8, a Ca2+-dependence maximum of 1 mM, and was inhibited by serine-proteinase inhibitors, especially tetrapeptidyl chloromethane derivatives with hydrophobic residues at the P-1 site. Kinetic studies also showed that tetrapeptides containing aromatic or hydrophobic residues at P-1 were the best substrates. A kcat./Km of 27 000 M-1 X S-1 was calculated for the peptide 3-carboxypropionyl-Ala-Ala-Pro-Phe-p-nitroanilide. The enzyme has significant activity against keratin, elastin and denatured type I collagen (Azocoll).

Chromatography, Gel↗