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Biomedical subjects

K Fukuyama

Publications and source records attributed to K Fukuyama.

At least 199 records · Page 11Linked to original sources
PubMed1980

Inhibition of tyrosinase activity by 4-tert-butylcatechol and other depigmenting agents.

4-tert-Butylcatechol (TBC) is an antioxidant widely used in industry and a potent depigmenting agent to the skin of the workers. In this study, tyrosinase was extracted from tissue-cultured human melanoma cells and purified by polyacrylamide gel electrophoresis. T1 and T2 tyrosinase, which migrated differently on the gels, were treated with TBC as well as other depigmenting agents and natural substrates of tyrosinase. Changes in the enzyme activity on dopa oxidation were quantified by photometric and radiometric analysis. The enzyme activity was inhibited by TBC and hydroquinone, but only at a high concentration that is toxic to tissue-cultured melanocytes. The activity was also decreased by tyrosine, but was increased by dopa, particularly at a lower concentration. The results indicated that the reported methodology is useful for testing the effects of chemicals with depigmenting or pigmenting potential. TBC and hydroquinone are inhibitors of tyrosinase at concentrations higher than 1 x 10(-3) M. Dopa and tyrosine alter tyrosinase activity in the second step of melanogenesis in the same manner that has been reported to occur in the first step-conversion of tyrosine to dopa.

Antioxidants↗
PubMed1980

Comparative studies of keratins isolated from psoriasis and atopic dermatitis.

Keratin proteins were extracted from scales of normal skin, clinically active psoriatic lesions, and atopic dermatitis. Filaments prepared by in vitro assembly upon dialysis of the proteins against a low ionic strength buffer were comparatively characterized by electron microscopy, SDS gel electrophoresis, and amino acid analysis. Filaments formed using keratin obtained from the skin of normal individuals were thin and wavy, whereas those formed using keratin isolated from the scales of psoriatic patients were straight and showed a tendency to assemble side by side. Filaments of atopic dermatitis were indistinguishable from those of normal individuals. Filaments of both normal and atopic dermatitis contained the protein band of 67,000 daltons, which was absent in filaments of psoriasis. In contrast, 2 protein bands of 54,000 and 57,000 daltons were only detectable in psoriasis. Amino acid analysis of these filaments further demonstrated that filaments of psoriasis differ from those of normal individuals in that they have a glycine content that is 60% of normal.

Amino Acids↗
PubMed1980

Detection of a fibrous component in keratohyalin granules of newborn rat epidermis.

Keratohyalin granules of frozen newborn rat epidermis were stained histologically and immunohistochemically and studied by light and electron microscopy. They showed a variety of reactivity to eosin, hematoxylin, uranyl acetate and rabbit monospecific antikeratin IgG. We found that good preservation of ultrastructure can be obtained from quickly frozen skin, and filamentous components remain after extraction of tissue substances by 0.14 M NaCl in 0.1 M-Tris-HCl buffer, pH 8.0. Furthermore, filaments in keratohyalin granules became immunologically reactive with rabbit anti-keratin IgG after extraction. Poststain with uranyl acetate further facilitated ultrastructural demonstration of filaments in the granules. These results indicate that filaments are one of the constituents of keratohyalin granules and the staining property changes occur in tonofilaments as they associate with other components to form keratohyalin granules.

Animals↗
PubMed1980

Eosinophil response in guinea pig skin to a low molecular weight eosinophil chemotactic factor extracted from livers of mice with schistosomiasis.

A low-molecular weight eosinophil chemotactic factor (ECF-G), isolated and partially purified from livers of mice with schistosomiasis, was injected intradermally into guinea pigs. Biopsies obtained were studied for inflammatory cell accumulation in the injected sites and compared with those in the control sites injected with phosphate buffered saline. Tissue eosinophilia was seen as early as 1 hr after injection of ECF-G, but not in the control site. The increase of eosinophilia appeared biphasic with peaks at 6 and 24 hr. Mast cells increased in both ECF-G and saline injected sites and the increase was still found at 120 hr after injection. Neutrophils also increased in both ECF-G and saline injected sites but disappeared within 48 hr. These findings indicate that ECF-G is a tissue and species nonspecific eosinophil chemotactic factor, and injection of ECF-G initiates interaction of eosinophils and mast cells in the skin.

Animals↗
PubMed1980

Effects of trace elements in polymerization of keratin proteins and destruction of the filaments by processing techniques for electron microscopy.

Keratin extracted from keratinized cells of newborn rats polymerizes into filaments in vitro and this polymerization has been shown to be greatly stimulated by addition of divalent cations. In this study we investigated the optimum conditions for filament formation by use of CaCl2, ZnCl2, and GdCl3, a trivalent lanthanide. It was found that a concentration about 10 times higher was required for elongation and formation of wider filaments with CaCl2 when compared with that for ZnCl2, GdCl3 caused enhanced polymerization with an even lower concentration. Effects of fixation(s) and other processing techniques used for routine electron microscopy on the polymerized keratin filaments were also examined by electron microscopy and SDS polyacrylamide gel electrophoresis. Degradation of keratin protein was detected in various steps involved in handling of the keratin filaments. These results indicate that ultrastructural studies of keratin in epidermal cells in situ may be improved by re-evaluation of presently used experimental procedures.

Animals↗
PubMed1980

Induction of T cell-independent eosinophilia in mice with polymyxin B and schistosome infection.

This study examined the elevation of blood eosinophil counts in athymic and thymus-intact mice after repeated injections of polymyxin B with and without infection by Schistosoma mansoni. In athymic mice, a modest, comparable eosinophilia occurred after polymyxin B injection or parasite infection alone, or after a combination of both. In thymus-intact mice, polymyxin B injection caused a similar low grade eosinophilia, and schistosome infection produced a much higher level of eosinophilia. The combination resulted in the highest levels during the early weeks after infection; this hyperresponsive phenomenon was most apparent following 5 to 7 weekly polymyxin B injections, and the total eosinophil count approximated that derived by adding the eosinophil counts induced by polymyxin B injections or schistosome infection alone. In spite of the changes in blood eosinophil counts, tissue eosinophilia in the liver revealed no apparent differences. Furthermore, in schistosome-infected and polymyxin B-injected thymus-intact mice, hepatic granulomas reached a maximal size earlier than in mice that were only infected, and there was an over-all reduction in mast cell counts. The findings indicate that a T cell-independent eosinophilia occurs under a variety of circumstances. In athymic mice, it accounts for all peripheral eosinophilia, whereas in thymus-intact mice, it operates independently from the well known T cell-dependent eosinophilia of parasite infections.

Animals↗
PubMed1979

Immunochemical comparison of histidine-rich protein in keratohyalin granules and cornified cells.

(1) Combination of techniques for extraction and purification of histidine rich protein established by several investigators were employed for comparison of histidine-rich protein in granular cells and cornified cells of newborn rats. (2) Histidine-rich protein extracted from the same cell fraction by two different techniques either in 1 M potassium phosphate buffer (Ugel) or in 4 M urea (Dale) showed identical elution profiles on CM 52 cellulose ion exchange chromatography and the same SDS polyacrylamide gel electrophoretic patterns. (3) Histidine-rich protein from granular cells contained polypeptides of larger molecular sizes than those in histidine-rich protein from cornfield cells, although amino acid composition of the two histidine-rich protein was non-distinguishable (histidine residue was more than 7%). (4) Antibodies raised in rabbits by injection of histidine rich protein from granular cells and that from cornfield cells immunologically cross-reacted. Furthermore, the antisera were found to be reactive over both keratohyalin granules and cornified cells, but not epidermal cells of the lower strata.

Animals↗
PubMed1979

Granulomatous inflammation in normal and athymic mice infected with schistosoma mansoni: an ultrastructural study.

Inflammatory cell types and their interrelationships were studied in hepatic schistosome egg granulomas by correlated light and electron microscopy in thymus-intact and athymic mice. Intact animals developed large granulomas composed of phagocytes, stimulated macrophages, epithelioid cells, eosinophils and mast cells. The lesions peaked in size between 10--14 weeks after infection and tended to heal after 16 weeks. In athymic mice only phagocytes, stimulated macrophages and possible epithelioid cells appeared in the granulomas which were much smaller and less well organised than in intact mice. Virtually no eosinophils or mast cells entered the granulomas. These findings support the idea that development of granulomatous inflammation per se is not determined by CMI, but T cell co-operation seems to be required for its full expression in schistosomiasis. Since CMI closely regulates ingress of eosinophils and mast cells into the granuloma, the nature of T cell co-operation probably occurs at several levels in this complex infectious granuloma.

Animals↗
PubMed1979

Biological properties of human melanoma cells in culture.

Three human melanoma cell lines derived from one primary and two metastatic tumors from three different patients were characterized for growth properties usually associated with malignant transformation; these include cell morphology, growth rate, saturation density, growth in semisolid media, colony-forming ability on contact-inhibited monolayers of normal fibroblasts and epithelial cells, and tumorigenicity in immunosuppressed mice. Variations in expression of aberrant properties were evident among the lines. One of the metastatic lines satisfied all the parameters of malignancy tested and the other showed a number of these properties, whereas the primary essentially fulfilled only one. These results suggest that cultured melanoma cells reflect the clinical variability often observed among melanoma patients and that metastatic melanoma seems to display a higher degree of malignant transformation than the primary.

Adult↗
PubMed1979

Dithiothreitol separation of newborn rodent dermis and epidermis.

Incubation of newborn mouse skin in media containing 0.01 M dithiothreitol at 4 degrees C for 2 hr reduces dermal-epidermal cohesion, and the 2 layers may be separated readily. Unlike other methods of separation, this technique does not require heating, nonphysiologic pH or ionic strength, or addition of proteolytic enzymes. The split occurs beneath the basal lamina. The separated epidermal sheet retains the periodic acid Schiff-positive "basement membrane," and the basal cells can incorporate 3H-thymidine.

Animals↗
PubMed1979

Fibrin deposition and clearance in chronic granulomatous inflammation: correlation with T-cell function and proteinase inhibitor activity in tissue.

Patterns of fibrin deposition were investigated by immunofluorescence microscopy in livers of thymus intact (TI) and athymic (AT) mice infected with Schistosoma mansoni. Thrombin and fibrinolysis inhibitor activity in tissue extracts also were measured. In TI mice fibrin was detected perivascularly by 6 weeks after infection and at 8 weeks it was found over the granulomas as they developed. Fibrin was cleared from the center of granulomas by 10 weeks. Thrombin inhibitor activity increased at 4 to 6 weeks but declined below control levels later as granulomas formed. Fibronolysis inhibitor activity, on the other hand, peaked at 9 to 12 weeks after infection. In AT mice extensive fibrin deposition was detected in the liver throughout the period when smaller and incomplete granulomas developed. Central clearing did not occur. Thrombin inhibitor activity greatly increased by 8 weeks after infection but fibrinolysis inhibitor activity remained unchanged. These findings suggest that fibrin deposition and firbinolysis are orderly events regulated in the lesions by proteinases and their inhibitors and this seems to be a general tissue reaction in the early stage of chronic granuloma formation. Since local clearance of fibrin in vivo and fibrinolysis inhibitor activity from tissue extracts studied in vitro are more evident in TI mice than in AT mice, it appears that T cell fu;ction is important in modulating the tissue response during granulomatous inflammation.

Animals↗
PubMed1979

Low molecular weight eosinophil chemotactic factor in granulomatous liver of murine schistosomiasis.

An acidic peptide, preferentially chemotactic for eosinophils, was extracted from livers of mice infected with Schistosoma mansoni. Sephadex G-25 column chromatography showed that the majority of the eosinophil chemotactic activity was detected in the fractions just after elution of the molecular marker vitamin B12 (m.w. 1355.4). This activity began to appear in the livers of some mice 5 weeks after infection. Peak activity was detected at 8 to 12 weeks after infection and persisted at least until 16 weeks. It was sensitive to carboxypeptidase-A. By Dowex-1 anion exchange chromatography, the activity eluted as a narrow peak at pH 3.1 TO 2.6 as shown for eosinophil chemotactic factor of anaphylaxis (ECF-A). The activity was also detected in a broad peak at pH 6.3 to 3.7. Unlike ECF-A, the activity was stable to boiling in both acid and alkali. These findings suggest that granulomatous liver of murine schistosomiasis-derived eosinophil chemotactic factor (ECF-G) may play a specific role in eosinophil accumulation in this chronic inflammation.

Acids↗
PubMed1978

Crystallization and a 5 A X-ray diffraction study of Aphanothece sacrum ferredoxin.

A chloroplast-type ferredoxin containing two non-heme iron and two labile sulfur atoms per molecule was prepared from Aphanothece sacrum. Crystals were obtained by dialysis against 75% saturated a-monium sulfate solution, and belong to the tetragonal system with cell dimensions a = b = 92.2 A and c = 47.6 A, containing four molecules in an asymmetric unit. The electron density map at 5 A resolution was calculated by using the best phase angles determined by the single isomorphous replacement method coupled with the anomalous dispersion effect. An anomalous dispersion difference Fourier map for the native crystal clearly showed four humps corresponding to the iron atoms in an asymmetric unit. The electron densis surface.

Binding Sites↗