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A Taïeb

Publications and source records attributed to A Taïeb.

At least 73 records · Page 4Linked to original sources
PubMed1998

Chimeric human epidermal reconstructs to study the role of melanocytes and keratinocytes in pigmentation and photoprotection.

Chimeric epidermal reconstructs made with Negroid melanocytes and Caucasoid keratinocytes (or vice versa) were studied before and after UVB irradiation to understand the respective roles of these cells in tanning and photoprotection, especially lipoperoxidation and enzymatic defences against free radicals. Using this approach, we have confirmed overall the theory of the epidermal melanin unit. We have also shown that melanocytes of poorly tanning Caucasoids, which have a comparatively higher content of unsaturated fatty acids in their cell membrane, are more prone to the peroxidative effects of UV light, and that keratinocytes participate in photoprotection via phototype-dependent antioxidant enzyme activities, especially for catalase.

Adult↗
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↗
PubMed1998

[Severe hemangiomas treated with interferon alpha-2b: seven cases].

INTRODUCTION: High-dose corticosteroids are the primary means of controlling alarming hemangiomas. However, only 2/3 of these life-threatening hemangiomas regress or are stabilized with corticosteroids: and for others there is no regularly safe and effective treatment. Contradictory publications have been reported about the efficacy of interferon (INF) alpha in hemangiomas, we report our experience concerning the management of 7 cases. PATIENTS AND METHODS: Seven infants have been treated with INF alpha-2b in our Pediatric Dermatology Unit. All hemangiomas were corticosteroid resistant. Hemangiomas were located on head and neck in 6 cases and on lower limb in one case in association with platelet trapping syndrome. Mean age at beginning of treatment was 7.5 months and mean duration of treatment was 5 months. INF alpha-2b was given daily in subcutaneous injections of 3 millions units per square meter of body surface area. RESULTS: After one month of treatment, 2 cases of facial hemangiomas showed a dramatic improvement, and INF alpha-2b was maintained for one year. One case was stabilized, but INF was ineffective in 3 cases after 2 months of treatment (the child with platelet trapping syndrome died at 4 months of age). The treatment had to be stopped in one case because of hepatitis. No long term side effects were noted with a mean follow-up of 27 months. CONCLUSION: INF alpha can be an interesting alternative therapy for infantile hemangiomas. However, only a minority of patients can be considered as excellent responders at current dosages and long term secondary effects cannot be excluded.

Anti-Inflammatory Agents↗
PubMed1998

[Lichen planus in children: role of the campaign for hepatitis B vaccination].

INTRODUCTION: Cutaneous lichen planus in children is a rare entity. To study its specific clinical and therapeutic features, we report on 8 cases seen in 5 years in a pediatric dermatology clinic. In parallel, this study addresses the role of HBV immunization campaigns in childhood lichen planus. OBSERVATIONS: Six boys and two girls with a diffuse form of lichen planus were studied. The mean age was 11 years. Four children were of skin types V and VI. Lesions followed Blaschko's lines in two children. One case was associated with atopic dermatitis. In half the cases--the most recent--the eruption was noted after HBV immunization. Biopsy specimens from seven children were reviewed and confirmed the diagnostic of lichen planus. Oral retinoids or corticosteroids were used successfully in six cases. DISCUSSION: Half of our cases confirmed the atypical features of lichen planus in childhood. This study confirms the predominance of lichen planus in children with pigmented skin suggesting a genetic predisposition. The eruption following Blaschko's lines suggests that a clonal keratinocytic population is the target of lichenoid inflammation. HBV immunization could be a stimulus triggering a cytotoxic lymphocyte-mediated reaction. The proportion of affected children was low in comparison with all children immunized. So lichen planus arises probably in predisposed children. This justifies surveillance in the pediatric and dermatologic medical communities.

Adolescent↗
PubMed1998

[Faun tail and sacral hemangioma associated with occult spinal dysraphism].

INTRODUCTION: Hemangiomas are the most frequent skin tumor of childhood. Usually, a "wait and see" policy is adopted. However, a sacral hemangioma may reveal occult neurodysraphism. CASE REPORT: MRI discovered lipomyelomeningocele and a tethered spinal chord in an asymptomatic 4-month-old boy with sacral hemangioma and faun tail. Because of absence of neurological defect only surgery of the caudal appendage was performed for the moment. DISCUSSION: Midline lombosacral lesions, as well as lipomas, hirsutism or pilonidal cyst, may be associated with occult spinal defect; the most severe is tethered chord. Renal or ano-genital anomalies can be also associated. CONCLUSION: MRI is necessary in case of midline sacral hemangioma to detect underlying anomalies.

Hemangioma↗
PubMed1997

Stereological image analysis of cultured human melanocytes observed by transmission electron microscopy.

The aims of the study were to write an image analysis (IA) program allowing the stereological quantification of human epidermal melanocyte melanization at the ultrastructural level and to specify the suitable preparative methods, in keeping with IA limits and stereological principles. Micrographs of cultured human melanocytes obtained in transmission electron microscopy were digitized with a scanner. The key step of the designed IA program is a thresholding based on the gray levels. Hence, gray level histograms (pixel frequency as a function of gray level) of melanocyte images exhibit a peak specific to melanin. The gray level thresholding used consists in isolating the melanin pixels that form profiles on a binary image and in storing the numerical data produced for a given melanocyte profile. These primary data are used to calculate numerous parameters via stereology with melanocyte cytoplasm and melanized melanosome as main reference spaces. The most important stereological parameters obtained are v(mi,cy) (melanin volume per average cell), v(mi,m) (melanin volume per average melanized melanosome), and nm (number of melanized melanosomes per average cell), and their validity is discussed. Melanocytes embedded in situ were abandoned for stereological reasons but pelleted melanocytes were found suitable. Using this computerized tool and stereology, we are able to perform quantitative studies producing varied data even from small cell samples. To our knowledge, this is the first stereological approach for quantifying intracellular melanization. A quantitative comparison of spectrophotometrical results (melanin assay) with stereological results obtained in ultraviolet B-irradiated Caucasian epidermal melanocytes will be performed in order to appraise this method.

Cytoplasm↗
PubMed1997

Infants with Kasabach-Merritt syndrome do not have "true" hemangiomas.

OBJECTIVE: In 1940 Kasabach and Merritt described an infant with a vascular anomaly, extensive purpura, and thrombocytopenia; they called his lesion "capillary hemangioma." Hemangioma is a benign tumor that grows in infancy and is characterized by proliferation of endothelial cells and regression during childhood. Although Kasabach-Merritt syndrome (KMS) is frequently mentioned as a possible complication of hemangioma, our experience suggests that the anatomic vascular lesion underlying the thrombocytopenia is not a "true," classic, involuting type of hemangioma of infancy and childhood. STUDY DESIGN: We reviewed the clinical and hemostasis data and the response to treatment in 22 cases of KMS, and we analyzed the biopsy specimens of 15 of them. RESULTS: Clinically none of the 22 patients had classic hemangioma. There was no female preponderance. All patients had severe thrombocytopenia (lowest platelet count = 3000/mm3) and consumption of fibrinogen. Histologically, none had the typical "capillary," involuting type of hemangioma of infancy: they exhibited either a tufted angioma or a kaposiform hemangioendothelioma pattern; all specimens also contained numerous abnormal lymphatic-like vessels; lymphatic malformation was the major component in two patients. The infants exhibited a heterogeneous response to a number of therapeutic regimens, as noted in other reports. Severe morbidity was present; three of our patients died, and one had leg amputation. "Residua" were, in fact, residual vascular neoplasia, variable in duration, and not a stable fibrofatty residuum, as in classic involuted hemangioma; only the hematologic phenomenon was "cured" after a period of years. CONCLUSIONS: KMS is a distinctive disease of infancy, but the underlying vascular lesion is not a "true," classic, involuting type of hemangioma of infancy. This is a different vascular tumor with a resemblance pathologically to either tufted angioma or kaposiform hemangioendothelioma in association with lymphatic-like vessels. Whether the underlying lesion in KMS is a single anatomic entity or heterogeneous cannot be definitely concluded from this study. We need a better understanding of the pathogenesis of KMS to improve our therapeutic management.

Biopsy↗
PubMed1997

Scoring of atopic dermatitis by SCORAD using a training atlas by investigators from different disciplines. ETAC Study Group. Early Treatment of the Atopic Child.

The ETAC (Early Treatment of the Atopic Child) study, a multi-national double-blind placebo-controlled randomized trials, has been in progress since 1994. Fifty-six centers in Europe and Canada participate in this study. A total of 817 children with atopic dermatitis [AD] were recruited. The severity of AD was scored using the SCORAD (objective criteria). Ninety-eight investigators (mostly pediatricians) were trained by three members of the European Task Force on Atopic Dermatitis [ETFAD] to standardize their objective SCORAD scoring (system developed by the ETFAD). The experts selected photographs and prepared a training atlas. The percentages of photographs assessed by the 98 non-expert investigators below, within and above the range of evaluations by the three experts were calculated. Taking over and underscoring together, edema/papulation was the easiest intensity item to score (82% within the range by the experts). The global symptom score, as well as lichenification, edema/papulation, oozing and excoriation registered by physicians with dermatological experience were not statistically significantly different from those by other. Erythema was statistically significantly better scored by those with dermatological experience. The results of the Euclidean Distance method showed that the item excoriations gave the largest distance. Erythema and excoriations were scored better by dermatologically experienced physicians (t-test, p = 0.042 and p = 0.063 respectively), but lichenification was better scored by non-dermatologically experienced physicians (p = 0.013). The extent of surface area involved in the disease was calculated on 3 sets of photographs. Most evaluations by the 98 nonexpert investigators were within the range of the experts. Dermatologically experienced physicians scored significantly better than the others (t-test, p = 0.006). This training program is useful for standardizing the scoring in AD and indicates that SCORAD can be used by investigators from different disciplines.

Anatomy, Artistic↗
PubMed1997

Clinical validation and guidelines for the SCORAD index: consensus report of the European Task Force on Atopic Dermatitis.

BACKGROUND: We have previously reported how the SCORAD index was designed. This cumulative index combines objective (extent and intensity of lesions) and subjective (daytime pruritus and sleep loss) criteria. AIMS: To study interobserver variability in scoring for objective SCORAD criteria and to optimize the scoring guidelines. MATERIAL AND METHODS: Three scoring sessions were organized in 1993-1994 in Hamburg, Bordeaux and Rotterdam totalizing 19 patients (14 children and 5 adults) and 23 physicians, among whom 12 participated in at least 2 scoring sessions; 169 evaluation sheets have been processed using the SCORAD File Marker Pro software. At each session, total body photographs and close-up views were taken of each patient, and this material was reviewed at the final evaluation. RESULTS: The extent of lesions according to the rule of nines showed interobserver variability mostly for patients with lesions of moderate intensity involving 20-60% of body surface. Intensity items were scored with more consistency overall, but variations subsided especially for oozing/crusts and lichenifications. Low and high scorer profiles and the benefit of training were noted. CONCLUSIONS: This study has allowed to optimize clinical scoring using the SCORAD system. A proposal has been made to grade the severity of atopic dermatitis according to objective criteria in three groups for inclusion in clinical trials. The SCORAD index remains the major criterion for follow-up in trials.

Adolescent↗
PubMed1997

A mutation in the XPB/ERCC3 DNA repair transcription gene, associated with trichothiodystrophy.

Trichothiodystrophy (TTD) is a rare, autosomal recessive disorder characterized by sulfur-deficient brittle hair and nails, mental retardation, impaired sexual development, and ichthyosis. Photosensitivity has been reported in approximately 50% of the cases, but no skin cancer is associated with TTD. Virtually all photosensitive TTD patients have a deficiency in the nucleotide excision repair (NER) of UV-induced DNA damage that is indistinguishable from that of xeroderma pigmentosum (XP) complementation group D (XP-D) patients. DNA repair defects in XP-D are associated with two additional, quite different diseases; XP, a sun-sensitive and cancer-prone repair disorder, and Cockayne syndrome (CS), a photosensitive condition characterized by physical and mental retardation and wizened facial appearance. One photosensitive TTD case constitutes a new repair-deficient complementation group, TTD-A. Remarkably, both TTD-A and XP-D defects are associated with subunits of TFIIH, a basal transcription factor with a second function in DNA repair. Thus, mutations in TFIIH components may, on top of a repair defect, also cause transcriptional insufficiency, which may explain part of the non-XP clinical features of TTD. Besides XPD and TTDA, the XPB gene product is also part of TFIIH. To date, three patients with the remarkable conjunction of XP and CS but not TTD have been assigned to XP complementation group B (XP-B). Here we present the characterization of the NER defect in two mild TTD patients (TTD6VI and TTD4VI) and confirm the assignment to X-PB. The causative mutation was found to be a single base substitution resulting in a missense mutation (T119P) in a region of the XPB protein completely conserved in yeast, Drosophila, mouse, and man. These findings define a third TTD complementation group, extend the clinical heterogeneity associated with XP-B, stress the exclusive relationship between TTD and mutations in subunits of repair/transcription factor TFIIH, and strongly support the concept of "transcription syndromes."

Adolescent↗
PubMed1997

Use of human skin reconstructs in the study of pigment modifiers.

OBJECTIVE: To assay drugs that modify pigmentation (ie, agents that either enhance or decrease pigmentation) in a predictive in vitro model, as such drugs have been previously studied in vivo on human and animal skin. DESIGN: An epidermis was reconstructed with human keratinocytes and melanocytes. Epidermal reconstructs with melanocytes were made according to a variant of the model of Pruniéras and colleagues. Reagents that alter melanogenesis such as isobutyl methylxanthine, 1-oleoyl-2-acetyl-sn-glycerol, kojic acid, and mequinol were introduced in the culture medium or used topically after 8 days of culture at the air-liquid interface. MAIN OUTCOME MEASURES: Macroscopic, colorimetric, histological (Fontana-Masson stain and dopa reaction), and biochemical studies were performed. RESULTS: The effect of pigment modifiers was demonstrated ex vivo as expected from in vivo data on skin color, numbers of melanocytes, melanosome transfer, and melanin content. CONCLUSION: These results will permit other investigators to use this model to assess the efficacy of novel molecules that alter pigmentation.

1-Methyl-3-isobutylxanthine↗