Biomedical subjects

V del Marmol

Publications and source records attributed to V del Marmol.

12 recordsLinked to original sources

PubMed2004

The role of combined oral contraceptives in the management of acne and seborrhea.

Acne and seborrhea (or facial oiliness) are related androgenic skin disorders which affect a high proportion of women after menarche. They can have a negative effect on psychological well-being and social life. Androgens play an important role in the pathogenesis of acne through the stimulation of sebum secretion, increasing sebaceous gland size and possibly through follicular hyperkeratinization. Conversely, estrogens decrease sebum production by suppressing gonadotropin release and androgen production and increasing sex hormone binding globulin production. One of the treatment options for these conditions is hormonal therapy, especially for women who require contraception. The effect of combined oral contraceptives in androgenic skin disorders depends on their estrogen:progestogen balance and on the antiestrogenic activity of the progestogen component. Improved understanding of what women value about oral contraceptives suggests that the choice of product should be tailored as much as possible to the individual. Several combined oral contraceptives containing new-generation progestogens (e.g. desogestrel, gestodene) or progestational antiandrogens (e.g. cyproterone acetate, chlormadinone acetate) have demonstrated efficacy in the treatment of women with acne, although comparisons between trials are difficult because of differing endpoints. Seborrhea has been less well studied, but the few studies that are available show an improvement in women with this condition using combined oral contraceptives.

Acne Vulgaris↗

PubMed2004

[Clinical tools for assessing hair loss].

The complaint of hair loss is quite frequent but merits close attention because it can be very stressful to the patient. A simple examination will allow in most cases to define the origin of the hair loss and reassure the patient rapidly as to its likely evolution if it is reversible. The examination must take into account the medical, chirurgical, gynaecological and dietary antecedents and the cosmetic habits. These elements must be situated in time and complemented by a clinical examination to define the loss as diffuse or localised and in the latter case, expose scar damage. The clinical examination will be associated with a trichogram and in certain cases with a biopsy or a squam prelevement. Further, the blood can be analysed for different metabolically and hormonal elements. Finally, the treatments already administered must be known in order to identify the beneficial and secondary effects, which will allow the definition of a new treatment, if required.

Alopecia↗

PubMed2004

[Androgenetic alopecia].

The physiopathology of androgenetic alopecia is linked to the action of the androgens of the bulbs pilairs of the scalp. The action of these androgens can be associated with the level of hormones in circulation and with the genetic predisposition which will influence the activity of these androgens at the periphery. The classifications of the evolution of alopecia will be done following Norwood for the male and following Ludwig for the female. Hormonal investigation will be effectuated on the female only in the case of research on or the identification of hyperandrogenia; this is essential in order to direct the therapy. The diagnose and the therapeutic follow-up are essentially clinical but can be assisted by a trichogram which will show-up the miniaturisation process of androgenetic alopecia and the telogen effluvium of the affected areas. The treatment of alopecia can be local or general. The local treatment will use a lotion of minoxidil 2 to 5% whether the patient is male of female. On males, an inhibitor of the 5 alpha reductase 2, finasteride, has shown its efficiency at a dose of 1 mg/day. On females oestroprogestatives will be used, if they are not counter-advised, associated with an anti-androgen: either cyproterone acetate or spironolactone. A therapeutic evaluation will be made after 6 months of treatment.

Alopecia↗

PubMed2000

Melanoma screening: results of the first one-day campaign in Belgium ('melanoma Monday').

BACKGROUND: Although the incidence of melanoma is increasing and many informative campaigns have been organized. The general population is still little informed about this tumour. AIMS: To organize a media campaign, with more relevant information and the opportunity for free skin inspections. METHODS: A 'Task Force' organized a media campaign in April 1999 and convinced 65% of the Belgian dermatologists to give up 4 h of their time to do free skin examinations for skin cancer on Monday 26 April 1999; it was called 'Melanoma Monday'. RESULTS: A total 2767 patients were screened. We found 25 melanomas and suspected 59 basal cell carcinomas. In the following 4 weeks another 141 melanomas were found. These 166 melanomas found in one month represent 15-20% of the total number of melanomas per year in Belgium. SUMMARY: A media campaign with relevant information combined with screening opportunities can lead to the early detection of melanomas in a large number of patients and can continue to alert people at risk in the following weeks.

Adolescent↗

PubMed1998

Comparison of HPLC and stereologic image analysis for the quantitation of eu- and pheomelanins in nevus cells and stimulated melanoma cells.

The aim of the study was to compare two methods of quantitating eumelanins and pheomelanins, pigments synthesized by melanocytes. One is based on the high performance liquid chromatography quantitation of specific degradation products of each melanin type. The other requires image analysis, transmission electron microscopy, and stereology. In a previous study, we showed good correlations between both methods for total melanin but not for eumelanins or pheomelanins. We describe here the same comparison in more pigmented cells (nevus cells and stimulated HBL melanoma cells). Transmission electron microscopy micrographs were image analyzed to generate several primary parameters. Stereology was used for estimating melanosomal maturation, intracellular melanin content, and the number of melanized melanosomes per cell, for total melanin, eumelanins, or pheomelanins. Our results showed a good correlation between both methods for total melanin, eumelanins, and pheomelanins with an r equal to 0.99, 0.91, and 0.93, respectively, when all the points were used in the linear regression analyses. In the melanoma cell group (HBL cells cultured in media of different compositions), the chemical and morphometric estimations were not parallel in the case of eumelanins and pheomelanins. In addition, the stereologic and high performance liquid chromatography pheomelanins to eumelanins ratios were still not correlated. These results demonstrate the relevancy of the stereologic method, but the low level of melanization, the possible lack of specificity of melanogenesis in melanoma cells, and a problem of sensitivity of the stereologic method in this context seem to be obstacles in obtaining better results. The utilization of normal human melanocytes could give some answers to our hypotheses.

Chromatography, High Pressure Liquid↗

PubMed1998

Quantification of eumelanin and pheomelanin: stereologic image analysis method.

OBJECTIVE: To develop an ultrastructural stereologic image analysis method allowing quantification of intracellular melanization. STUDY DESIGN: First, in the field of image analysis, a newly elaborated segmentation method, SEM2, was compared with a previously described method based on gray level histograms. Only SEM2 allows the segmentation of melanin in micrographs of poorly melanized melanocytes. Second, in the field of stereology, estimation of cell volume remains problematic in the case of mixed cell populations. This problem is approached by the comparison of stereologic alternatives and cytochemistry (L-3, 4-dihydroxyphenylalanine reaction) in epidermal melanocytes and melanoma cells from several in vitro experiments. The cytochemical approach was found to be the best choice. RESULTS: Concerning the quantification of eumelanin and pheomelanin, the alkali elution method, permitting the specific dissolution of pheomelanin on ultrathin sections, was validated in normal human follicular melanocytes. CONCLUSION: These results allow us to envisage the stereologic quantification of eumelanin and pheomelanin at the ultrastructural level. At present our method is undergoing evaluation by comparison with the present method of reference based on high-performance liquid chromatography.

Adolescent↗

PubMed1997

Comparison of TRPs from murine and human malignant melanocytes.

Most of our knowledge of the mammalian tyrosinase related protein (TRP) activities is derived from studies using murine melanoma models, such as B16 or Cloudman S-91 melanocytes. Owing to the high degree of homology between the murine and human enzymes, it has been assumed that their kinetic behaviour could be similar. However, the protein sequences at the metal binding sites of the murine and human enzymes show some differences of possible functional relevance. These differences are more significant in the metal-A site than in the metal-B site. By using three human melanoma cell lines (HBL, SCL, and BEU), we have studied the catalytic abilities of the human melanogenic enzymes in comparison to those obtained for the counterpart murine enzymes isolated from B16 melanoma. We have found that TRP2 extracted from all cell lines show dopachrome tautomerase activity, although the activity levels in human malignant melanocytes are much lower than in mouse cells. Reconstitution experiments of the human enzyme indicate that TRP2 has Zn at its metal binding-sites. Although mouse tyrosinase does not show DHICA oxidase activity, and this step of the melanogenesis pathway is specifically catalyzed by mouse TRP1, the human enzyme seems to recognize carboxylated indoles. Thus, human tyrosinase could display some residual DHICA oxidase activity, and the function of human TRP1 could differ from that of the murine protein. Attempts to clarify the nature of the metal cofactor in TRP1 were unsuccessful. The enzyme contains mostly Fe and Cu, but the reconstitution of the enzymatic activity from the apoprotein with these ions was not possible.

Animals↗

PubMed1996

Tyrosinase and related proteins in mammalian pigmentation.

Tyrosinase is the key enzyme in pigment synthesis, initiating a cascade of reactions which convert the amino acid tyrosine to the melanin biopolymer. Two other tyrosinase-related proteins (TRP) are known, TRP-1 (probably DHICAoxidase) and TRP-2 (DOPAchrome tautomerase). These proteins show about 40% homology, and recent results have indicated that the genes might be derived from a common ancestor. We will discuss recent findings on genomic organization, and on the proteins and their presumed function, which is important for eumelanin synthesis in mouse and man.

Animals↗

PubMed1996

Cysteine deprivation promotes eumelanogenesis in human melanoma cells.

Melanocytic cells can produce two types of pigment, pheomelanin or eumelanin. We used two types of human melanoma cell lines to explore the regulation of pigmentation by biochemical and enzymatic studies. These two cell lines were previously designated as either pheomelanotic or of mixed type when cultured in a medium rich in cysteine. We analyzed the effects of L-cysteine depletion on melanin synthesis and the involvement of the tyrosinase-related proteins in the production of both eumelanin and pheomelanin. Cultures were exposed to L-cysteine concentrations ranging from 206 to 2.06 microM, and the following parameters were measured: tyrosine hydroxylase activity, intracellular L-cysteine and glutathione concentrations, eumelanin and pheomelanin formation, and tyrosinase-related protein-1 and -2 mRNA levels. Extracellular L-cysteine depletion significantly increased tyrosine hydroxylase activity and promoted both eumelanogenesis and visible pigmentation in both lines. In contrast, pheomelanogenesis was increased only in the pheomelanotic cell line. Whereas eumelanogenesis was apparent upon L-cysteine depletion, tyrosinase-related protein-1 expression was not induced in the pheomelanotic cells, and tyrosinase-related protein-2 expression remained unchanged. Thus, tyrosinase-related protein-1 mRNA expression seems to be concomitant with eumelanogenesis when the L-cysteine concentration is high, but does not appear essential for eumelanogenesis at low L-cysteine concentrations. The mechanisms governing pheomelanin to eumelanin balance are dependent on L-cysteine, glutathione, and tyrosinase-related protein-1 expression, but none of these factors alone appears to be dominant in directing the synthesis of a particular type of melanin.

Cysteine↗

PubMed1994

African origin of an intragenic deletion of the human P gene in tyrosinase positive oculocutaneous albinism.

Oculocutaneous albinism (OCA) is a genetically heterogeneous hypopigmentation disorder. One of the two major autosomal recessive forms involves the tyrosinase gene (OCA1), while the other form (OCA2) has recently been associated with alterations of the P gene on chromosome 15. OCA2 is about twice as common as OCA1 in African and African-American populations. We now describe an interstitial deletion that removes a single exon of the P gene. In a large family from an inbred population of tri-racial origin, all individuals with OCA2 were found to be homozygous for this allele. Moreover, the same mutant P allele was detected in several unrelated African American individuals with OCA2, but not in Caucasians with OCA2. The detection of the same allele in two unrelated Africans with OCA2 indicates an African origin for this allele.

Africa↗

PubMed1993

TRP-1 expression correlates with eumelanogenesis in human pigment cells in culture.

We have investigated the relationship in human cultured normal and malignant melanocytes between the accumulation of mRNAs encoding tyrosinase and tyrosinase-related protein-1 (TRP-1), the activity of tyrosinase and the presence of melanin. Tyrosinase mRNA correlates with tyrosinase activity and with the presence of pheomelanin, eumelanin or both melanin types. In contrast TRP-1 mRNA is only detectable in cells containing eumelanin, which suggests a role for TRP-1 in the eumelanin synthesis pathway.

Base Sequence↗

PubMed1993

Glutathione depletion increases tyrosinase activity in human melanoma cells.

The aim of the present work was to estimate the effect of intracellular glutathione depletion on melanogenesis in human melanoma cells. We determined tyrosine hydroxylation activity, the rate-limiting step of the pathway, and 14C-melanin formation, an assay reflecting the global eumelanogenic pathway. Intracellular glutathione was depleted by treatment with buthionine-S-sulfoximine, a well-known inhibitor of gamma-glutamylcysteine synthetase. The intracellular depletion of glutathione was substantial after 20 h of incubation with 50 microM buthionine-S-sulfoximine, although a significant effect could be observed after 6 h. Tyrosine hydroxylase activity increased in parallel with glutathione depletion, to reach 160% with respect to the control values during 24 h of buthionine-S-sulfoximine treatment. We have found the response to buthionine-S-sulfoximine to be dose dependent and the two different human cell lines HBL and LND1 to have similar, if not identical, responses. 14C-melanin formation assay revealed even greater activation, up to 400% of the control values. This indicates that glutathione depletion may have two distinct effects: first, a direct one on tyrosinase activity and, second, an effect on the promotion of eumelanogenesis. The stimulation of tyrosine hydroxylase can be explained by a possible inactivation of the enzyme by endogenous thiol compounds rather than by a direct effect of buthionine-S-sulfoximine itself on tyrosinase. The data suggest that thiol compounds may play a role for stimulation of melanogenesis by ultraviolet radiation.

Antimetabolites, Antineoplastic↗