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E Karg

Publications and source records attributed to E Karg.

16 recordsLinked to original sources
PubMed1991

Hydrogen peroxide as a mediator of dopac-induced effects on melanoma cells.

Dopac increases tyrosinase activity and exerts cytotoxic effects in cultures of human melanoma cells. The possible role of hydrogen peroxide in these actions was examined. Catalase (100 micrograms/ml) completely reversed the cytotoxic action of 0.3 mM dopac and reduced its tyrosinase-stimulating effect by approximately one half. The results show that extracellular hydrogen peroxide is a mediator of both the tyrosinase-stimulating and cytotoxic actions of dopac. Analysis of the degradation products of melanin from dopac-treated melanoma cells after hydriodic acid (HI) hydrolysis revealed the presence of aminohydroxy-phenylacetic acid (AHPAc). This substance is obtained by HI hydrolysis of melanin formed by oxidation of cysteinyl-dopac. Thus, the presence of AHPAc indicates that dopac is transported into the melanocytes where it serves as a substrate for tyrosinase.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

Glutathione in human melanoma cells. Effects of cysteine, cysteine esters and glutathione isopropyl ester.

Thiols are of great importance for the regulation of many cellular functions including metabolism, transport and cell protection. In this study the usefulness of L-cysteine methyl and octyl esters, of N,S-diacetyl-L-cysteine methyl ester and glutathione isopropyl ester as cellular cysteine and GSH delivery systems was investigated in the human IGR 1 melanoma cell line. The L-cysteine methyl and octyl esters proved to be highly toxic to the cells. Treatment of the cultures with 1 mM N,S-diacetyl-L-cysteine methyl ester or 3 mM glutathione isopropyl ester for 24 h resulted in marked elevation of the cellular glutathione level without apparent or with slight cell loss, respectively. Thus the administration of the latter two compounds seems to be suitable for inducing GSH elevation in the cultured melanoma cells.

Acetylcysteine↗
PubMed1990

Enzyme release from cultured human melanoma cells.

The lysosomal enzyme beta-hexosaminidase and the melanocyte specific enzyme tyrosinase were examined in human melanoma cell cultures. The beta-hexosaminidase activity of the medium was approximately 40% of the total cellular activity after 24 h, while after 48 h the activity in the medium was twice that of the cells. The tyrosinase activity in the medium was 5% and 19% of the total cellular activity after the 24 h and 48 h incubation, respectively. The low level of lactate dehydrogenase activity in the medium after 24 as well as 48 h of incubation indicated that the release of beta-hexosaminidase and tyrosinase was not due to membrane injury. The data suggest, that 1) beta-hexosaminidase may be a candidate for tumor markers in malignant melanoma, and 2) the tyrosinase activity found in sera of melanoma patients may be due, at least partly, to enzyme release by living cancer cells.

Cell Line↗
PubMed1989

Modulation of glutathione level in cultured human melanoma cells.

The effects of buthionine sulphoximine (BSO) treatment on cellular glutathione (GSH) content and on the cytotoxic action of menadione were investigated in cultured IGRI human melanoma cells. Addition of BSO (10(-8)-0.5 X 10(-3) M) to the cultures resulted in a dose- and time-dependent depletion of cellular GSH. BSO (10(-5) and 10(-6) M) did not influence cell multiplication up to 48 h, as determined by trypan blue staining. Menadione (3 X 10(-5) M) treatment decreased the cellular GSH concentration and also reduced cell number after a 24 h exposure. Its cytotoxicity was increased by BSO (10(-5), 10(-6) M), though the potentiating effect was moderate.

Antimetabolites↗
PubMed1989

Adenylate cyclase activity in homogenates of human melanoma cells. Effect of alpha-MSH and isoprenaline.

The effects of the alpha-melanocyte-stimulating hormone (alpha-MSH) (10(-7)-10(-5) M) and the beta-adrenoceptor agonist isoprenaline (10(-9)-10(-4) M) on adenylate cyclase (AC) activity were investigated in homogenates of the human IGR 1 melanoma cells with or without additional GTP. Basal AC activity was increased by the administration of 10 microM GTP. Alpha-MSH had no effect on cyclic AMP (cAMP) accumulation, while isoprenaline stimulated AC activity in a dose-dependent manner.

Adenylyl Cyclases↗
PubMed1989

Stimulation of tyrosinase by dihydroxy phenyl derivatives.

Isoprenaline (0.3 mM) moderately increased the tyrosinase activity of cultured human melanoma cells, while another beta-adrenoceptor agonist, terbutaline (1-3 mM) and a catechol compound, dopac (0.1-0.3 mM) induced a several fold increase in the enzyme activity. Isoprenaline (0.3-1 mM) and dopac (0.3-1 mM) also exerted pronounced toxic effects on the cells. The data suggest: 1) a possible role for beta-adrenoceptors in the regulation of human melanogenesis; 2) two different ways of action for isoprenaline in inducing tyrosinase elevation; 3) the possible usefulness of dopac as a chemotherapeutic agent.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1986

[Recurrent disseminated infundibulofolliculitis].

A white male patient with disseminated, pruritic, follicular papules on the skin is reported. Histologically, an inflammatory infiltration around the infundibulum, perifollicular oedema and spongiosis of the follicular epithelium were demonstrated. The lesions failed to respond to therapy. On the basis of the clinical and histological findings, we suggest that this is a case of disseminated and recurrent infundibulofolliculitis, which was first described by Hitch and Lund in 1968.

Folliculitis↗
PubMed1985

Old man.

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Aged↗
PubMedDate not supplied

Melanin-related biochemistry of IGR 1 human melanoma cells.

Cultured melanoma cells have been of great value in the study of pigment metabolism. IGR 1 human melanoma cells, established by Dr Christian Aubert, produce melanin in large quantities. These cells have been used for isolation of human tyrosinase which enzyme has not previously been obtained in a pure form. IGR 1 cells contain large amounts of 5-S-cysteinyldopa which is the quantitatively most important catecholic amino acid. This review deals with the metabolism of dopa, cysteinyldopa, glutathionyldopa, cysteine and glutathione, compounds of central importance in pigment metabolism. The information available on tyrosinase, catecholic compounds and on thiols in IGR 1 melanoma cells makes these cells most suitable for further investigation of the metabolism of human melanoma cells.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

Alteration of glutathione level in human melanoma cells: effect of N-acetyl-L-cysteine and its analogues.

The effects of N-acetyl-L-cysteine (L-NAC), N,N-diacetyl-L-cystine (oxidized form of L-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 mM L-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 toxic effects resulting in cell loss.

Acetylcysteine↗