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Biomedical subjects

W L Epstein

Publications and source records attributed to W L Epstein.

At least 91 records · Page 5Linked to original sources
PubMed1984

Immunohistochemical demonstration of S-100 protein antigen-containing cells in beryllium-induced, zirconium-induced and sarcoidosis granulomas.

S-100 protein has been detected in epidermal Langerhans cells, interdigitating reticulum cells, and large mononuclear cells of cutaneous T-cell lymphomas. Experimental data imply these cells are involved in the presentation of antigens and/or maturation of T-lymphocytes. The authors studied the morphology and distribution of S-100 protein antigen-containing cells in cutaneous sarcoidosis and metal-induced granulomas, both immunogenic and foreign-body types, with light and electron microscopic immunoperoxidase technics. Immunological reaction was seen in Langerhans cells, peripheral nerves, and granulomatous lesion dendritic cells. The latter showed a large, irregular nucleus and branching cytoplasm. They intermingled with other mononuclear cells in the granulomas but not with organized epithelioid cells. Morphometric quantification of dendritic cells in the three types of granulomas revealed statistically significant differences (P less than 0.005) and electron microscopy demonstrated their typical cytoplasmic appearance, without Birbeck granules. The increased number of dendritic cells in immunogenic granulomas, and their shared antigenic components with Langerhans cells suggest they act as accessory cells in eliciting the granulomatous response.

Beryllium↗
PubMed1984

Effects of 4-tertiary butyl catechol on glutathione-metabolizing enzymes in vivo and in vitro.

4-Tertiary butyl catechol (TBC) causes depigmentation in humans and animals and stimulates formation of pheomelanosomes. In this study, we investigated the effects of noncytotoxic doses of TBC on glutathione S-transferase (GST) activity in the skin of Uscd strain mice and B16 murine melanoma cells in culture, in relation to changes in activities of glutathione reductase (GR) and gamma-glutamyl transpeptidase (GGT) reported to be involved in pheomelanogenesis. Occurrence of pheomelanosomes in skin melanocytes was demonstrated by electron microscopy and reduction (25%) of eumelanin content in melanoma cells was shown by spectrophotometry. Topical application of 1 M TBC-DMSO-acetone solution on the ear skin elevated GST activity about 27%, and activities of GGT and GR to 35% and 19%, respectively, within 1 week. Melanoma cells cultured in 10(-4) M TBC-containing medium for 2 h showed no changes in GST and GGT activities, but 12% increase of GR activity during the first 12 h. Activities of all 3 enzymes was elevated (11-17%) 24 h later. The elevation detected by 48 h was 25% for GST, 26% for GGT, and 14% for GR. The findings were interpreted to show that depigmentation produced by the antioxidant results from stimulated pheomelanogenesis through activation of glutathione-metabolizing enzymes and suppressed oxidation of eumelanin intermediates.

Animals↗
PubMed1984

Appearance of T-cell subpopulations during the time course of beryllium-induced granulomas.

Employing monoclonal antibodies that identify T-helper/inducer or T-suppressor/cytotoxic cells, we investigated the T-lymphocyte subsets in hypersensitivity granulomas developed after beryllium salt injection. T-helper/inducer cells were detected at all stages of the lesions, including early nonspecific inflammatory lesions seen at 3 weeks after injection. They formed clusters intermingled with the mononuclear phagocytes in granulomatous lesions, but were not found among the epithelioid cells. In contrast, T-suppressor/cytotoxic cells were slow to appear in the lesions and constituted very small numbers in mature epithelioid cell granulomas of 9-11 weeks. These findings suggest that T-helper/inducer cells may be responsible for the evolution of the perivascular infiltrate of mononuclear cells. Furthermore, appearance of T-helper/inducer cells without T-suppressor/cytotoxic cells may contribute to the development and organization of epithelioid cells and their maturity in the granulomatous lesions.

Antibodies, Monoclonal↗
PubMed1984

Purification and properties of aminoendopeptidase from rat epidermis.

An aminoendopeptidase isolated from 2-day-old rat epidermis was purified to apparent homogeneity by the procedures of ammonium sulfate fractionation, DE-52 column chromatography, Sephadex G-200 gel filtration, and CM-52 and DEAE-Sepharose 6B column chromatography. Enzymatic activity was exhibited only in the presence of sulfhydryl compounds and further enhanced by addition of 5 mM EDTA. It was inhibited by p-chloromercuribenzoate, other sulfhydryl blocking reagents, and o-phenanthroline. The monomer form of the enzyme is Mr = 52,000 +/- 2,300 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, but a native form was considered to be Mr = 400,000 +/- 26,000 having an isoelectric point of pH 5.25. Among synthetic substrates the enzyme hydrolyzed amino acid 2-naphthylamide derivatives and L-leucine amine (L-LeuNH2) most effectively. N-alpha-benzoyl-DL-arginine-2-naphthylamide (BANA) was the only endopeptidase substrate for the enzyme and a competitive inhibitor for its aminopeptidase activity. Protein substrates have not yet been found. The pH optimum is 7.5 and in a range of pH 6.5-7.5 it is stable at 37 degrees C for 30 min but loses about 50% of its activity at 50 degrees C.

Animals↗
PubMed1983

Reduction in eumelanin by the activation of glutathione reductase and gamma-glutamyl transpeptidase after exposure to a depigmenting chemical.

Topical application of 4-tertiary butyl catechol (TBC) causes vitiligo in the skin of man and animals, and previous electron microscopic studies showed pheomelanin formation in the affected areas. In the present study, we investigated changes of enzyme activities, eumelanin content and amount of sulfur in tissue cultured human melanoma cells exposed to the depigmenting chemical. TBC enhanced glutathione reductase activity without changing the eumelanin content by 24 hr after exposure and subsequently (by 42 hr) increased gamma-glutamyl transpeptidase activity and sulfur content in the cells with a decrease in eumelanin content. It is suggested that this chemical alters the types of melanin formed by modulation of these enzyme activities.

Catechols↗
PubMed1983

Glutathione reductase activity in skin exposed to 4-tertiary butyl catechol.

The effect of 4-tertiary butyl catechol (TBC), a potent depigmenting chemical, on glutathione reductase (GR) in pigmented ear skin of hairless mice was investigated. Three topical applications of TBC, which cause neither skin color changes nor melanocyte degeneration, induced an increase in enzyme activity. Since the same treatment resulted in pheomelanin formation as evidenced by electron microscopy, it is suggested that the GR increase correlates at least in part with changes in melanocyte metabolism. This enzyme generates a reduced form of glutathione which may be involved in the formation of glutathionedopas, substrates for hydrolytic enzymes to produce cysteinyldopas, and pheomelanin. Elevation of GR may be an indication of melanogenesis before clinical skin color changes due to TBC appear. It may be used for the early detection of occupational leukoderma.

Animals↗
PubMed1983

The epidermal barrier to Schistosoma mansoni infection.

The stratified epithelium serves as protection for underlying tissues and organs, and the structural fitness of the epidermal cells has been extensively reported. We studied the possible roles played by the epidermis as a barrier against the migration of Schistosoma mansoni larvae. Freshly shed cercariae were collected and placed on the back skin of 2-day-old rats. Electron microscopy of biopsies taken at various intervals showed the larvae and their secretory granules in keratinocytes in which the cytoplasm had become homogeneous in appearance. SDS gel electrophoresis showed the digestion of purified epidermal keratin (60K protein) by a proteinase secreted from cercariae, but this activity was inhibited by an inhibitor purified from epidermal cells. These findings suggest that epidermal cells function both structurally and chemically as a barrier against cercariae invasion.

Animals↗
PubMed1983

Zinc-binding proteins of newborn rat epidermis.

Hematoxylin stain was used to demonstrate localization of Zn2+-binding proteins in the skin of the newborn rat. The binding protein showed different solubilities and the zinc binding was dissociated at pH 4.5. Epidermal proteins were extracted stepwise in Tris-HCl buffer containing NaCl at 4 degrees C and 37 degrees C, 1 M potassium phosphate, and 4 M urea. Zn2+-binding protein was obtained from each extract by means of Zn2+ chelate affinity chromatography. We detected elution of histidine-rich protein from the affinity column with a pH 4.5 buffer by 3H-histidine labeling and immunoreactivity to rabbit IgG directed to histidine-rich protein. Amino acid analysis demonstrated that the compositions of the Zn2+-binding proteins soluble in the different extracts not only resemble each other, but are essentially the same as those of histidine-rich protein of the newborn rat skin as previously reported. However, sodium dodecylsulfate gel electrophoresis showed multiple protein bands ranging from Mr less than 25,000 to Mr greater than 200,000. The findings indicate that histidine-rich protein of different forms and solubility exists, in the epidermis and may be involved in the biological function of the cells through metal-binding.

Amino Acids↗
PubMed1982

Partial purification and characterization of an inhibitor from newborn-rat epidermis with activity against the proteinase of Schistosoma mansoni cercariae.

The penetration of cercariae through the skin initiates infection of the host with the human trematode parasite Schistosoma mansoni. Many larvae fail to migrate into the living epidermal cell layer. In order to determine if chemical as well as mechanical barriers to cercarial skin penetration exist, inhibitory activity of epidermal cell extracts against the proteinase obtained from cercarial secretions was assayed. An inhibitor was purified 50-fold by gel filtration on Sephadex G 75 and cation exchange chromatography at pH 5.8 and 4.9. The inhibitor has a relative molecular mass (Mr) of approx. 40 000-53 000. Oxidation of the inhibitor with N-chlorosuccinimide eliminated its inhibitory activity and thus indicated a critical methionine residue. The inhibitor was active against a wide spectrum of serine proteinases: porcine pancreatic elastase, human granulocyte elastase, bovine trypsin, and bovine alpha-chymotrypsin. However, no inhibition was detected against papain or clostridial collagenase. The inhibitor did not cross react with antiserum to human or rat serum alpha 1-proteinase inhibitor.

Animals↗
PubMed1982

Further characterization of cysteine proteinase inhibitors purified from rat and human epidermis.

Cysteine proteinase inhibitors isolated from rat and human epidermis were purified to homogeneity and had isoelectric points of pH 4.31 and pH 5.10, respectively, Both inhibitors caused noncompetitive inhibition to the same degree against papain (EC 3.4.22.2), but the activity of human inhibitor against rat liver cathepsins B (EC 3.4.22.1), H (EC 3.4.22.16), and L (EC 3.422.-) was more effective than that of rat inhibitor. Dependency on pH was observed with rat inhibitor for cathepsins B and H, and with human inhibitor for cathepsin L. The reaction of the inhibitors with papain and cathepsins H and L occurred immediately, while the inhibition reaction of cathepsin B increased progressively during a preincubation time up to 40 min. Incubation at pH 7.0 maximized the progressive inhibitory activity. These findings demonstrate that cysteine proteinase inhibitors from rat and human epidermis inhibited a variety of cysteine proteinases. However, the inhibitor and enzyme interaction depends upon the enzyme, inhibitor source, and experimental conditions such as pH and preincubation time.

Animals↗
PubMed1982

Ultrastructural demonstration of chemical modification of melanogenesis in hairless mouse skin.

We investigated chemical and physical modifications of the genetically determined ultrastructure of melanosomes. The flank skin of hairless mice was treated with ultraviolet energy (UV) shorter than 320 nm or with a combination of a photosensitizer and UV (PUVA treatment). All melanosomes in the induced melanocytes and those in resident melanocytes in the ear skin showed eumelanogenesis, although the degree of melanin deposition differed considerably according to the induction process. Eumelanogenesis was most advanced in the resident melanocytes while PUVA-induced melanocytes showed more immature premelanosomes. We then topically applied 4-tertiary butyl catechol on the skin. The depigmenting agent caused an appearance of pheomelanosomes. The alteration in melanogenesis was seen most distinctly in premelanosomes of the PUVA-induced cells. Altered ultrastructure was also observed in matured melanosomes; this change was most apparent in the resident melanocytes. These findings indicate that cells with eumelanogenesis may undergo pheomelanogenesis. The present study demonstrated effects of chemicals on genetically determined function of melanocytes by quantitative analysis of melanosome ultrastructure.

Animals↗
PubMed1982

Cellular localization of thiol-proteinase inhibitor in the epidermis of the newborn rat.

Subcellular distribution of a thiol-proteinase inhibitor protein was determined in the epidermis of the newborn rat by light and electron microscopy. This protein was highly soluble in basal cells and concentrated on ribosomes in the perinuclear region. Solubility in Tris buffer decreased in granular and cornified cells in which the protein appeared on polysomes which were attached on other cellular structures such as dense homogenous deposits and tonofilaments. The protein also appeared to be deposited on the plasma membrane and became insoluble in Tris buffer at 37 degrees C, but solubilized in 1 M phosphate buffer. Location of the protein around keratohyalin granules or by the plasma membrane suggested that the inhibitor protein bound to cysteine-rich protein of the epidermis with or without forming a thiol-proteinase inhibitor complex. The thiol-proteinase inhibitor protein seems to contribute to epidermal cell differentiation at multiple points through changes in its solubility and subcellular localization from basal cells to cornified cells.

Animals↗
PubMed1982

Differences in the behavior of SH-protease inhibitor of rat epidermis on cathepsins B and H.

1. SH-protease inhibitor was purified from newborn rat epidermis and its activity against cathepsins B and H compared using alpha-N-benzoyl-DL-arginine-2-napthylamide as a substrate. 2. Preincubation of the inhibitor with the enzymes at 37 degrees C resulted in increased inhibitor activity for cathepsin B but not for cathepsin H: pH 7.0 was more effective than the lower pH for the increase. 3. The inhibition was noncompetitive regardless of the preincubation conditions and the inhibition was greater for cathepsin H than cathepsin B. 4. These findings suggest that there is an SH-protease inhibitor of newborn rat epidermis which has different biological behavior against cathepsins B and H.

Animals↗
PubMed1982

Autotransplantation of hepatic granulomas into the skin of mice with Schistosoma mansoni infection.

Hepatic egg granulomas of mice infected with Schistosoma mansoni were transplanted into the skin of the same animal and changes occurring to macrophages, eosinophils, and mast cells over time were studied by light and electron microscopy and by autoradiographic techniques. Disappearance of cellular components about the egg granulomas occurred within 1 week; the entire implant became encapsulated by inflammatory cells and stroma. By 3 weeks mononuclear cells and macrophages reorganized the granulomas around the eggs and neutrophils disappeared. Activated macrophages contained both secretory rough endoplasmic reticulum and lysosomal-dense bodies. Granuloma size increased up to 5 weeks after implantation and mast cells and eosinophils tended to migrate into the granulomas. The mast cell index always remained lower than in the original hepatic granulomas, while eosinophils were seen in large numbers. During 3 to 8 weeks after implantation mononuclear cells undergoing DNA synthesis in the granulomas ranged from 2.9-4.8%. Some 3-week-old autotransplants were injected with 3H-thymidine and biopsied from 1 to 21 days later. Labeled mononuclear cells peaked in the granulomas by 10 days (24%) and the numbers fell off sharply after that. These findings indicate that autologously implanted schistosome egg granulomas can be maintained successfully in the skin for prolonged periods with marked ingress of macrophages and eosinophils. The autoradiographic data suggest the lesions are high turnover granulomas.

Animals↗