ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00339.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00340.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

In order to clarify the role of tyrosinase (E.C. 1.14.18.1) in the cytotoxicity of 4‐hydroxyanisole (4HA) in vivo, we have compared the therapeutic effects of 4HA on the B16 melanoma and Harding‐Passey melanoma, which differ significantly in their tyrosinase content. The observed therapeutic effects are moderate and similar in both tumors. Therefore, there is no evidence for an increase of the cytotoxic effect of 4HA by tyrosinase in vivo. Application of 4HA to mice carrying B16 melanoma and Harding‐Passey melanoma results in an inhibition of [3H]‐TdR incorporation into melanoma DNA as well as into DNA of liver, intestine, kidney, and spleen. There is no selective activity on melanoma cells by 4HA in vivo. Therefore, in the therapy of human melanoma by 4HA, side effects on normal tissues cannot be e

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00255.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The effects of N‐acetyl‐l‐cysteine (l‐NAC), N,N‐diacetyl‐l‐cystine (oxidized form ofl‐NAC) and N‐acetyl‐d‐cysteine on the intracellular glutathione (GSH) level and their toxicity were investigated in the human melanoma cell culture IGR1.l‐NAC applied in 3 mM concentration for 24 hr decreased; when applied for 48 hr it did not alter the intracellular GSH level. Treatment with 1 mMl‐NAC for 24 hr had no effect on cellular glutathione, whereas the same concentration applied for 48 hr resulted in an increase in the level of GSH. Both concentrations also induced cell injury as determined by protein assay and trypan blue staining. N,N‐diacetyl‐l‐cystine (0.5 and 1.5 mM, 24 hr) induced a decrease in cellular glutathione content without any apparent cell toxicity.d‐NAC (1 and 3 mM, 24 hr) did not influence the GSH level of the melanoma cells; however, it had tox

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00256.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Our objective was to determine using electron microscopy how nonagouti (a), lethal yellow (Ar), and albino (c2J) genes affect the program of mouse hairbulb melanosome differentiation; 1,921 hairbulb melanosomes from four genotypes (a/a C/C = B,Ay/a C/C = Y, a/a c2J/c2J= BA, and Ay/a c2J/c2J= YA) were scored for developmental stage, length, and width.Qualitative and quantitative electron microscopy revealed the following. An albino locus‐induced diminution of melanosome size suggests that the albino locus is involved in structural features of melanosomes not directly related to the synthesis and deployment of tyrosinase. Ratio data on melanosome length‐to‐width confirm that the agouti locus determines melanosome shape, either spherical or elliptical; melanization is not required for melanosomes to achieve their agouti‐locus‐determined shapes. YA (Ay/a c2J/c2J) melanosomes, characterized by poorly organized matrices, absence of active tyrosinase, unusually large membrane invaginations, and significantly smaller dimensions than those of BA (a/a c2J/c2J), showed additive effects of both Ayandc2Jalleles.These data suggest that the albino locus plays a structural as well as functional (tyrosinase) role in the differentiation of mouse hairbulb melanosomes. The agouti locus, even in the absence of melanization, directs melanosome shape either via synthesis and deployment of agouti‐locus‐encoded matrix proteins or by other structural factors. The additive effects of Ayand c2Jalleles in compound YA mutants document the importance of specific interactions both functional and structural between agouti an

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00257.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00341.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00342.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00343.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00344.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

An in vitro crustacean (freshwater shrimp,Macrobrachium potiuna) erythrophore bioassay for chromatophorotropins and other pigment cell agonists is described. The present assay is a quantitative method that determines the pigment responses with the aid of an ocular micrometer. The pigment granules within the erythrophores are dispersed out into the dendritic processes of the cells when the isolated carapace is placed in physiological solution. This bioassay provides, therefore, a method for measuring the response of the pigment cells to aggregating agents such as pigment concentrating hormone (PCH). This bioassay is sensitive to PCH at a concentration as low as 3 ± 10−12M. Calcium ionophore A23187 mimics the actions of PCH, but, unlike the hormone, the Ionophore‐induced pigment aggregation is irreversible after physiological solution rinses. Therefore, chromatophorotropic activities of pigment dispersing agents, such as pigment dispersing hormones (PDH), can be determined on ionophore‐treated erythrophores. The potencies of α‐PDH and β‐PDH show a threefold difference (not significant). Because of its convenience and its ability to make an objective determination of the bidirectional pigment movements within erythrophores, this bioassay is a suitable method for further structure‐activity studies of the various chromatophorotropins and

ISSN:0893-5785    

DOI:10.1111/j.1600-0749.1990.tb00258.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY