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J G Morelli

Publications and source records attributed to J G Morelli.

At least 55 records · Page 3Linked to original sources
PubMed1994

Autoregulation of endothelin-1 secretion by cultured human keratinocytes via the endothelin B receptor.

We investigated endothelin-1 (ET-1) receptor expression on normal human keratinocytes (HK). We show that HK express the ETB receptor isoform and respond to ET-1 with a 2.7-fold increase in intracellular free calcium. HK did not respond to ET-1 with increased proliferation; however, 30 nM ET-1 caused a 51.7% decrease in ET-1 accumulation in HK-conditioned medium. We propose that HK ET-1 receptors function in autocrine regulation of ET-1 secretion.

Cell Division↗
PubMed1994

Human melanoma cells express functional endothelin-1 receptors.

Current evidence suggests that endothelium-derived factors enhance human melanoma vascular invasion. Therefore, we studied human melanoma cell expression of receptors to the endothelium-derived peptide, endothelin-1 (ET-1), and determined if they respond to ET-1 with proliferation and chemokinesis. Human metastatic melanoma cell lines were found to have specific, saturable, high affinity ET-1 binding. Northern analysis and competitive inhibition studies confirmed that melanoma cells express the ETB receptor isoform. Ten nanomolar ET-1 caused an 8.2 to 25.5-fold increase in intracellular free calcium. ET-1 was found to be a weak mitogen for melanoma cells, however, melanoma cell chemokinesis was significantly increased by ET-1. These data suggest that ET-1 may be involved in providing a chemokinetic and growth factor environment that enhances perivascular proliferation and invasiveness of melanoma cells.

Calcium↗
PubMed1994

Ras mutations in human melanoma: a marker of malignant progression.

In this study we address whether there is an association between ras mutations and disease progression in malignant melanoma. DNA was extracted from 100 paraffin-embedded melanomas and sequences around the 12th, 13th and 61st codons of N-, H-, and K-ras were amplified using the polymerase chain reaction and probed for single base pair mutations using synthetic oligonucleotide probes. Thirty-six melanomas contained mutations, which in 25 cases (69%) occurred at the 61st codon of N-ras. The results from dot blot hybridizations were confirmed by subcloning and sequencing the polymerase chain reaction products from two tumors. No ras mutations were found in Clark's level I melanomas, whereas 19% of level II and 45% of the more advanced primary tumors contained ras mutations (Chi squared test: p < 0.05). The median Breslow thickness of primary melanomas with ras mutations was 0.72 mm, significantly thicker than the 0.42 mm of melanomas without mutations (Mann-Whitney U test, p = 0.042). Ras mutations were found more frequently in primary tumors from continuously exposed skin (56%) than tumors from intermittently or non-sun exposed sites (21%). Fifty percent of locally recurrent and 47% of metastatic melanomas had ras mutations. We conclude that ras mutations occur in a subset of melanomas from sun-exposed skin as a feature of tumor progression.

Genes, ras↗
PubMed1993

Metabolism of leukotriene B4 by cultured human keratinocytes. Formation of glutathione conjugates and dihydro metabolites.

Six previously unidentified leukotriene (LT) B4 metabolites formed during incubation of LTB4 with human keratinocytes in primary culture indicate the importance of the 12-hydroxyeicosanoid dehydrogenase pathway in LTB4 metabolism. The ultraviolet absorption spectra obtained for all keratinocyte metabolites revealed the presence of a conjugated diene structural moiety rather than the conjugated triene structure of LTB4. Metabolites were characterized using fast atom bombardment-mass spectrometry, gas chromatography-mass spectrometry of the pentafluorobenzyl ester, trimethylsilyl ether derivatives and specific degradation reactions. The previously identified 10,11-dihydro-LTB4 and 10,11-dihydro-12-epi-LTB4 were observed as well as 20-OH-10,11-dihydro-LTB4, consistent with the reductase pathway of LTB4 metabolism. This pathway involves initial formation of 12-oxo-LTB4 catalyzed by 12-hydroxyeicosanoid dehydrogenase followed by reduction by delta 10-reductase. The most lipophilic metabolite of LTB4 was identified as 10-hydroxy-4,6,12-octadecatrienoic acid which could result from beta-oxidation reactions of LTB4 following reduction of the 10,11-double bond. One of the most abundant metabolites was characterized as 3,7,14-trihydroxy-8,10,16- docosatrienoic acid which could result from fatty acid elongation following reduction of the 10,11-double bond. Additional abundant LTB4 metabolites were identified that result from glutathione conjugation of 12-oxo-LTB4. These were characterized using fast atom bombardment-mass spectrometry and by chemical degradation using hypochlorous acid as well as transpeptidases. These metabolites were identified as 5,12-dihydroxy-6-glutathionyl-7,9,14-eicosatrienoic acid (c-LTB3), 5,12-dihydroxy-6-cysteinyl-glycyl-7,9,14-eicosatrienoic acid (d-LTB3) and 5,12-dihydroxy-6-cysteinyl-7,9,14-eicosatrienoic acid (e-LTB3). We propose that these metabolites result from a 1,8 Michael-type addition of glutathione to the 12-oxo-LTB4 intermediate.

Biotransformation↗
PubMed1993

Cultured human keratinocytes synthesize and secrete endothelin-1.

The human epidermal-melanin unit exists as a complex interplay of cell-cell interactions. Melanocytes synthesize melanin and transfer it to the surrounding keratinocytes, which, in turn, produce factors that affect melanocyte homeostasis, growth, and melanization. Endothelin-1 (ET-1), a vasoconstrictor peptide produced by endothelial cells, has recently been shown to stimulate human melanocyte proliferation and tyrosinase activity. To investigate the possibility that keratinocytes synthesize and secrete ET-1, we grew human keratinocytes in a defined serum-free medium and measured ET-1 levels in the keratinocytes and the keratinocyte-conditioned medium. Northern analysis of keratinocyte total RNA also was performed. We found that human keratinocytes express preproET-1 mRNA and translate the message to ET-1 protein, which is secreted into the keratinocyte medium. Human keratinocytes produced ET-1 in a time-dependent manner with total production of 20.1 +/- 1.1 pg ET-1/10(6) cells at 24 h (n = 7). Although total ET-1 production (secreted plus cell-associated ET-1) was similar, the proportion of secreted versus cell-associated ET-1 varied widely among the different donors. We have found that human keratinocytes synthesize and secrete ET-1 in vitro. From these data we believe that the keratinocyte could be an in vivo epidermal source of this melanocyte growth and pigmentation factor.

Blotting, Northern↗
PubMed1993

Melanocyte movement in vitro: role of matrix proteins and integrin receptors.

During the repigmentation of vitiliginous skin, melanocytes migrate from the outer root sheath of the hair follicle into the depigmented skin. We hypothesize that this requires changes in the local microenvironment that are conductive to melanocyte migration. One important change in the microenvironment could be the localized production of matrix proteins. We have previously employed time-lapse photography to evaluate the effect of inflammatory mediators and cytokines on melanocyte movement. We have adapted this system to study the effect of matrix proteins on melanocyte movement in vitro. Type IV collagen significantly increases melanocyte migration, whereas laminin and fibronectin have no effect. Cell/matrix interactions are in part controlled by cell-surface integrins. Integrins have been demonstrated to be important in controlling the migration of many cell types. We demonstrate that melanocytes express cell-membrane alpha 2, alpha 3, and alpha 5 integrins and that the enhanced melanocyte migration on type IV collagen is inhibited by specific function-blocking antibodies to integrins alpha 2 and alpha 3, but not to alpha 5 integrins.

Antibodies↗
PubMed1993

Influence of inflammatory mediators and cytokines on human melanocyte function.

The fully differentiated human melanocyte functions as a necessary and integral part of the epidermis, synthesizing melanin in intracellular organelles and transferring these pigment-containing organelles to surrounding keratinocytes. The epidermal environment contains multiple inflammatory mediators, cytokines, and growth factors that may alter constitutive melanocyte function. Constitutive melanocyte function can also be markedly altered by release of such mediators in inflammatory dermatoses. Many of the same factors can also be released by ultraviolet radiation and psoralen+ultraviolet A treatment. These inflammatory mediators and cytokines affect not only melanocyte pigment production, but also proliferation, differentiation, immunologic susceptibility and cytotoxicity, inflammatory mediator, cytokine and matrix protein production, and cell movement. The effect of inflammatory mediators and cytokines on melanocytes and the regulation of these effects are an active area of investigation.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1992

Pulsed dye laser treatment of benign cutaneous pigmented lesions.

Superficial benign cutaneous pigmented lesions that commonly present to the dermatologists and plastic surgeons have been treated by many conventional modalities such as dermabrasion, depigmenting creams as well as several types of lasers. Many of these treatment modalities lack specificity of injury, which has meant that normally pigmented and even non-pigment containing structures such as collagen as well as the hyperpigmented lesion itself have all been indiscriminately destroyed. This has resulted variously in hypopigmentation, hyperpigmentation, in addition to scar formation in some cases. A coaxial 504 nm laser with a pulse duration of 300 nsec was used to treat fifty two patients with superficial benign cutaneous pigmented lesions. Although the number of treatments required to clear the lesion varied according to the type of lesions being treated, on average, between 2 and 4 treatments were required to completely eradicate the superficial benign cutaneous pigmented lesions using 504 nm pulsed dye laser. The skin at the site successfully cleared of the pigmented lesion remained normal in skin color, texture, markings, and mobility.

Child, Preschool↗
PubMed1992

Evaluation of cutaneous algogenic responses to bradykinin and inhibition by bradykinin analogs.

Bradykinin has long been postulated to have a major role in physiologic human pain production. We have developed a method to systematically quantify the algogenic response to bradykinin in human skin by the direct application of bradykinin to suction blister bases. After determination of the pain threshold to bradykinin, we examined the ability of synthetic peptide analogs of bradykinin to block bradykinin-induced pain. One of the six analogs (B4642) inhibited bradykinin-induced pain with at least one concentration in all subjects tested. This result could not be predicted on the basis of inhibition of bradykinin binding to its guinea-pig ileum receptor or to previous studies of bradykinin-induced pain production in animal models. This peptide may have an eventual role as a physiologic pain inhibitor.

Amino Acid Sequence↗