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Biomedical subjects

Jean Marie Naeyaert

Publications and source records attributed to Jean Marie Naeyaert.

8 recordsLinked to original sources
PubMed2006

Consistent cutaneous imaging with commercial digital cameras.

OBJECTIVE: To demonstrate how to improve the reproducibility and accuracy of digital images of the skin taken with commercially available digital cameras by transforming them to a standard color space, sRGB. METHODS: Our computer algorithm transforms digital images to the standard sRGB color space. It is based on a card with a number of color squares with known colorimetric properties that is included in the image, thereby removing any ambiguity about the color information in the image. Reproducibility and accuracy of the method were assessed by comparing images of color squares with known colorimetric properties taken with different digital cameras at different exposures and zoom settings. RESULTS: Although calibrated images exhibit markedly improved precision and accuracy compared with noncalibrated images, all variability of the imaging process cannot be eliminated. CONCLUSION: With a little care and effort, a calibrated color chart, and computer software, it is possible to greatly improve the quality of clinical imaging in dermatology and possibly other fields of medicine.

Calibration↗
PubMed2006

Subjective and objective evaluation of noncultured epidermal cellular grafting for repigmenting vitiligo.

BACKGROUND: Noncultured epidermal cell transplantation in vitiligo permits the coverage of relatively large areas without culturing cells. OBJECTIVE: To investigate the effectiveness of noncultured epidermal cell transplantation in treating stabilized vitiligo using objective and subjective evaluation methods. METHODS: Noncultured autologous melanocytes and keratinocytes were grafted in a hyaluronic-acid-enriched suspension on superficially laser-abraded vitiligo lesions in 40 patients with refractory stable vitiligo (30 with generalized and 10 with localized vitiligo). The repigmentation was evaluated 3-12 months after grafting using a digital image analysis system. Furthermore the treatment was evaluated from the patients' point of view with the DLQI (Dermatology Life Quality Index) and a 'global assessment'. RESULTS: The mean percentage of repigmentation, evaluated at the last follow-up visit, was 72% (median 84%), and a repigmentation of >or=70% was observed in 62% of patients. The best results were achieved in the neck and the presternal region. A subjective evaluation was performed in half of the subjects. The mean DLQI score at inclusion (6.95, SD = 6.68, n = 20) was significantly decreased after treatment (p = 0.013, mean 3.85, SD = 4.13, n = 20). The patients were satisfied with the achieved result, found it worthwhile to undergo the treatment and would choose it again. CONCLUSION: According to both subjective and objective evaluation methods, noncultured epidermal cell transplantation is promising in patients with stable vitiligo.

Adolescent↗
PubMed2005

Different approaches for assaying melanosome transfer.

Many approaches have been tried to establish assays for melanosome transfer to keratinocytes. In this report, we describe and summarize various novel attempts to label melanosomes in search of a reliable, specific, reproducible and quantitative assay system. We tried to fluorescently label melanosomes by transfection of GFP-labeled melanosomal proteins and by incubation of melanocytes with fluorescent melanin intermediates or homologues. In most cases a weak cytoplasmic fluorescence was perceived, which was probably because of incorrect sorting or deficient incorporation of the fluorescent protein and different localization. We were able to label melanosomes via incorporation of 14C-thiouracil into melanin. Consequently, we tried to develop an assay to separate keratinocytes with transferred radioactivity from melanocytes after co-culture. Differential trypsinization and different magnetic bead separation techniques were tested with unsatisfactory results. An attempt was also made to incorporate fluorescent thiouracil, since this would allow cells to be separated by FACS. In conclusion, different methods to measure pigment transfer between donor melanocytes and acceptor keratinocytes were thoroughly examined. This information could give other researchers a head start in the search for a melanosome transfer assay with said qualities to better understand pigment transfer.

Animals↗
PubMed2004

Double-blind placebo-controlled study of autologous transplanted epidermal cell suspensions for repigmenting vitiligo.

OBJECTIVES: To investigate the efficacy of epidermal noncultured cellular grafting in patients with vitiligo and the role of postinflammatory, spontaneous, or UV-induced pigmentation in obtaining repigmentation. DESIGN: A prospective, randomized, double-blind, placebo-controlled study. SETTING: Ambulatory patients in an institutional practice. Patients were followed up for 3 to 12 months. PATIENTS: A total of 33 paired, symmetrically distributed leukodermic lesions, all resistant to therapy, were observed in 28 patients. Nineteen patients appeared to have a stable vitiligo (group 1), whereas there was doubt about the stability of the disease in 9 patients (group 2). INTERVENTION: After laser ablation, a hyaluronic acid-enriched cellular graft was applied to 1 lesion while the paired lesion received placebo. Three weeks later all lesions were exposed to UV irradiation twice per week for approximately 2 months. MAIN OUTCOME MEASURES: Primarily, the percentage of repigmentation was assessed after 3, 6, and 12 months using a digital image analysis system. The repigmentation pattern was also evaluated after 1 and 3 months. RESULTS: A strongly significant difference between cellular grafts and placebo was observed after 3, 6, and 12 months (P<.001, P = .002, and P = .002, respectively). In group 1, repigmentation of at least 70% of the treated area was achieved in 55%, 57%, and 77% of the actively treated lesions 3, 6, and 12 months after treatment, whereas in group 2 repigmentation of at least 70% of the treated area was not observed at any time point. The repigmentation pattern was diffuse in 94% of the responding patients. CONCLUSIONS: After a strict preoperative selection for disease stability, transplantation resulted in repigmentation of at least 70% of the treated area in most actively treated vitiligo lesions. Repigmentation was primarily caused by the transplanted melanocytes.

Adolescent↗
PubMed2004

Rab27b is up-regulated in human Griscelli syndrome type II melanocytes and linked to the actin cytoskeleton via exon F-Myosin Va transcripts.

Patients with the autosomal recessive Griscelli-Pruniéras syndrome type II are immunologically impaired and have an unusual silvery-grey hypopigmented colour of scalp hair, eyelashes and eyebrows but no noteworthy pigmentary abnormalities of the skin. In most Griscelli patients, the RAB27A gene, which encodes a small GTPase that is associated with the melanosome membrane in melanocytes, is mutated. Here we discuss a genomic RAB27A deletion found in a 21-month-old Moroccan Griscelli patient. Additionally, we provide evidence that the loss of functional Rab27a in melanocytes of this Griscelli patient is partially compensated by the up-regulation of Rab27b, a homologue of Rab27a. By real-time quantitative PCR and western blot analysis, we found that Rab27b mRNA and protein, expressed at low levels in normal human melanocytes, is significantly up-regulated in melanocytes derived from this patient. Our immunofluorescence and yeast two-hybrid screening studies reveal that Rab27b can form a tripartite complex on the melanosome membrane with Melanophilin, a Rab27a effector, and protein products of Myosin Va transcripts that contain exon F. Our data suggest that up-regulated Rab27b in melanocytes of the Griscelli patient can partially take over the function of Rab27a, which could explain the fact that this patient had an evenly pigmented skin and was able to tan.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Interactions of human Myosin Va isoforms, endogenously expressed in human melanocytes, are tightly regulated by the tail domain.

Primary human epidermal melanocytes express six endogenous isoforms of the human actin-associated myosin Va motor protein, involved in organelle transport. As isoforms containing exon F are most abundant in melanocytes, we hypothesized that these isoforms probably have a melanocyte-specific function. To uncover the biologic role of the six isoforms we introduced enhanced green fluorescent protein (eGFP)-myosin Va tail constructs in human melanocytes. We found that the medial tail, undergoing alternative splicing, has to be expressed in combination with the globular tail in order to obtain clear colocalization with organelles. Our data show that isoforms lacking exon F but containing exon D are associated with vesicles near the Golgi area. Myosin Va isoforms containing exon F are able to colocalize with and influence melanosome distribution by indirect interaction with rab27a and direct interaction with melanophilin. These results indicate that the myosin Va medial tail domain provides the globular tail domain with organelle-interacting specificity.

Adaptor Proteins, Signal Transducing↗
PubMed2002

Diffuse plane normolipaemic xanthomatosis in a patient with chronic lymphatic leukaemia and monoclonal gammopathy.

Diffuse plane normolipaemic xanthomatosis is a well-defined uncommon condition characterized by yellow-orange plaques involving the eyelids, neck, upper trunk, buttocks and flexural folds. Over half of the reported cases are associated with lymphoproliferative disorders. The condition may arise as a result of perivascular deposition of lipoprotein-immunoglobulin complexes. We present a female patient with clear clinical features of diffuse plane xanthomatosis associated with chronic lymphatic leukaemia and monoclonal gammopathy. In this patient, we found evidence of complement consumption supporting the hypothesis that complexes of lipoprotein and paraprotein are formed. Lipid electrophoresis of fasting serum revealed the presence of a faint precipitate at the application slot, also indicative of the presence of protein-lipid complexes.

Aged↗