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Biomedical subjects

W Westerhof

Publications and source records attributed to W Westerhof.

At least 55 records · Page 3Linked to original sources
PubMed1997

Laser treatment for further depigmentation in vitiligo.

BACKGROUND: In patients with vitiligo, sometimes the greatest part of the skin has already lost its melanocytes. The remaining pigmented patches can be removed by using strong bleaching creams, but many adverse events have been reported with this treatment. A new depigmentation therapy could be treatment with a Fluby laser. METHODS: Before treatment, the patients filled out a questionnaire about their vitiligo history. Eight patients with remaining pigmentation of the arms, hands, and face were treated once with a Ruby laser. Patients were monitored for developing repigmentation during the 9 months after treatment. RESULTS: In patients with a positive Koebner phenomenon, a permanent state of depigmentation was reached after laser therapy. None of the treated patients showed severe side-effects. CONCLUSIONS: Ruby laser treatment can be an effective, fast, and safe method for removing cosmetically disturbing remnants of normal pigmentation in vitiligo patients with a positive Koebner phenomenon.

Adolescent↗
PubMed1997

[Vitiligo].

Explore the source record for details and available documents.

Diagnosis, Differential↗
PubMed1997

Treatment of vitiligo with UV-B radiation vs topical psoralen plus UV-A.

OBJECTIVE: To compare the efficacy and safety of 2 treatment modalities, topical psoralen plus UV-A (PUVA) with unsubstituted psoralen and 311-nm UV-B radiation, in patients with vitiligo. DESIGN: This intervention study was designed as a before-and-after trial with 2 arms, in which patients were consecutively included. PATIENTS: Male (n = 99) and female (n = 182) patients, who predominantly had skin type III, with extensive, generalized vitiligo of more than 3 months' duration. INTERVENTIONS: Two patient groups were investigated. The first group of patients was treated for 4 months with either topical PUVA (n = 28) or 311-nm UV-B radiation (n = 78). The second group of patients, treated twice weekly with 311-nm UV-B radiation, was followed up for 3 (n = 60), 6 (n = 27), 9 (n = 37), or 12 months (n = 51). RESULTS: Thirteen (46%) patients in the first group treated with topical PUVA showed repigmentation after 4 months. Fifty-two patients (67%) in the 311-nm UV-B treatment group showed repigmentation after 4 months. After 3 months, 5 patients (8%) in the second group showed more than 75% repigmentation of lesional skin compared with 32 patients (63%) after 12 months. As in other treatment modalities, the face showed good repigmentation, whereas hands and feet responded poorly. No adverse effects were encountered with treatment with narrowband UV-B radiation, contrary to those seen with topical PUVA treatment. The cumulative UV-B dose was very small compared with that of the topical PUVA treatment. CONCLUSIONS: According to our results, the treatment of patients with vitiligo with 311-nm UV-B radiation is as efficient as with topical PUVA and has fewer adverse effects.

Administration, Topical↗
PubMed1996

Foetal human melanocytes: in situ detection, in vitro culture and differentiation characteristics at 6-11 weeks EGA.

In vivo, melanocytes were detected in epidermis from human tissue of 6.5 weeks estimated gestinational age (EGA) and older. We have successfully established melanocyte monocultures from tissue of 9 to 10 weeks EGA. To our knowledge, this is the first report on physiology of human foetal melanocytes in monoculture. In culture, such melanocytes retained foetal characteristics. Proliferation rates noted were markedly higher (approximately 2.7-fold) when compared to those in cultures of neonatal melanocytes. Moreover, when analyzing cellular phenotypes by markers for cells of the melanocytic lineage, foetal cells isolated from tissue of 9 weeks EGA reproducibly showed expression of the high molecular weight (HMW) antigen and c-kit to an extent intermediate to that found in neonatal melanocytes and M14 melanoma cells. Such differential expression was not observed if cells were isolated from tissue of 10 weeks EGA, indicating that the foetal environment provides essential differentiation stimuli during the 10th week of gestation. Moreover, these results are supportive of the theory that malignant transformation involves a process of dedifferentiation. In all, human foetal melanocyte culture provides a useful model to investigate pigment cell differentiation.

Biomarkers, Tumor↗
PubMed1996

Extracellular matrix characterization during healing of full-thickness wounds treated with a collagen/elastin dermal substitute shows improved skin regeneration in pigs.

We investigated the architecture of the extracellular matrix (ECM) during healing of full-thickness wounds in the pig. Two different treatments, one based on epidermal transplantation (split skin mesh grafts, SP wounds) and one consisting of a combination of epidermal transplantation and a dermal matrix substitute (MA wounds) were compared. The dermal matrix consisted of native bovine collagen coated with elastin hydrolysate. The latter treatment reduced wound contraction and improved tissue regeneration. The expression patterns of fibronectin, von Willebrand factor, laminin, chondroitin sulfate, and elastin, detected by immunohistochemistry, were examined in time and indicated different stages of healing. During the early phase of healing the dermal matrix induced more granulation tissue, a different fibronectin expression pattern, and rapid vascular cell ingrowth (von Willebrand factor). Furthermore, in the MA wounds chondroitin sulfate was detected earlier in the basement membrane and fibronectin staining disappeared more rapidly. During later stages of healing, chondroitin sulfate expression was selective for areas in which ECM remodeling was active; in these specific areas elastin staining reappeared. ECM remodeling and elastin regeneration occurred both in the upper and lower dermis for the MA wounds but only in the upper dermis for the SP wounds. Electron microscopic evaluation of the wounds after 2 weeks showed many myofibroblasts in the SP wounds, whereas in the MA wounds cells associated with the dermal matrix had characteristics of normal fibroblasts. The results suggest that the biodegradable dermal matrix served as a template for dermal tissue regeneration, allowed faster regeneration, and improved the quality of healing in large full-thickness skin defects.

Animals↗
PubMed1996

Presence of T cells and macrophages in inflammatory vitiligo skin parallels melanocyte disappearance.

Evidence for the involvement of cellular immunity in the etiopathogenesis of the hypopigmentary disorder vitiligo is provided by rare cases of inflammatory vitiligo. Nonlesional, perilesional, and lesional skin biopsies from three inflammatory vitiligo patients were immunohistochemically analyzed. The composition of inflammatory infiltrates present in perilesional skin was analyzed by antibodies to T cells (CD2, CD3, CD4, and CD8), Langerhans cells (CD1a), and macrophages (CD36 and CD68). The presence of activation markers on inflammatory cells was evaluated by analysis of HLA-DR, interleukin-2 receptor, and HECA452 expression. The presence or absence of melanocytes was determined by the antibody NKI-beteb. Moreover, the abundance of matrix molecule tenascin was semi-quantified using T2H5. Results indicate that within perilesional skin, epidermis-infiltrating T cells exhibit an increased CD8/CD4 ratio and increased cutaneous lymphocyte antigen and interleukin-2 receptor expression. These cells are frequently juxtapositionally apposed to remaining melanocytes. In perilesional dermis, CD68+OKM5- macrophages were more numerous than in lesional or nonlesional skin. Keratinocytes as well as melanocytes consistently express major histocompatibility complex class II antigens along stretches of basal and suprabasal layers in perilesional epidermis. Moreover, inflammation is accompanied by increased tenascin content. Although these observations do not permit differentiation between the immune infiltrates being a result as opposed to the cause of the disease process, results presented in this study are very suggestive of involvement of local immune reactivity in melanocyte destruction.

Adult↗
PubMed1995

Adherence, proliferation and collagen turnover by human fibroblasts seeded into different types of collagen sponges.

We describe an in vitro model that we have used to evaluate dermal substitutes and to obtain data on cell proliferation, the rate of degradation of the dermal equivalent, contractibility and de novo synthesis of collagen. We tested three classes of collagenous materials: (1) reconstituted non-crosslinked collagen, (2) reconstituted collagen that was chemically crosslinked with either glutaraldehyde, aluminium alginate or acetate, and (3) native collagen fibres, with or without other extracellular matrix molecules (elastin hydrolysate, hyaluronic acid or fibronectin). The non-crosslinked reconstituted collagen was degraded rapidly by human fibroblasts. The chemically crosslinked materials proved to be cytotoxic. Native collagen fibres were stable. In the absence of ascorbic acid, the addition of elastin hydrolysate to this type of matrix reduced the rate of collagen degradation. Both elastin hydrolysate and fibronectin partially prevented fibroblast-mediated contraction. Hyaluronic acid was only slightly effective in reducing the collagen degradation rate and more fibroblast-mediated contraction of the material was found than for the native collagen fibres with elastin hydrolysate and fibronectin. In the presence of ascorbate, collagen synthesis was enhanced in the native collagen matrix without additions and in the material containing elastin hydrolysate, but not in the material with hyaluronic acid. These results are indicative of the suitability of tissue substitutes for in vivo application.

Ascorbic Acid↗
PubMed1995

Repigmentation in vitiligo vulgaris by autologous minigrafting: results in nineteen patients.

BACKGROUND: Minigrafting is a successful therapy for localized vitiligo but has never been reported for vitiligo vulgaris. OBJECTIVE: Our purpose was to evaluate the efficacy of minigrafting in vitiligo vulgaris. METHODS: In 59 patients with stable vitiligo vulgaris, a minigraft test was done by implanting two minigrafts in the lesion to be grafted. Patients were selected for grafting when spread of pigment was observed within 3 months. The rate of repigmentation was evaluated by digital image analysis. RESULTS: Twenty-three patients (36 lesions), of 24 with a positive minigraft test, were grafted. The results of 19 patients were analyzed, showing 80% to 99% repigmentation in 14 lesions, 50% to 80% repigmentation in 10 lesions, and zero to 50% repigmentation in 12 lesions. Time of observation varied from 3 to 12 months after grafting. Best results were observed after 9 to 12 months. In all patients with a positive Koebner phenomenon depigmentation of the minigrafts developed. CONCLUSION: Autologous minigrafting is an effective therapy for stable vitiligo vulgaris in a selected group of patients.

Adolescent↗
PubMed1995

Reduced wound contraction and scar formation in punch biopsy wounds. Native collagen dermal substitutes. A clinical study.

In full-thickness skin wounds dermal regeneration usually fails, resulting in scar formation and wound contraction. We studied dermal regeneration by implantation of collagenous matrices in a human punch biopsy wound model. Matrices were made of native bovine collagen I fibres, and either hyaluronic acid, fibronectin, or elastin was added. Matrices were placed in 6-mm punch biopsy holes in seven patients (biopsies were used for the grafting of leg ulcers), and covered with a protective semi-permeable polyether urethane membrane. Histology, wound contraction and dermal architecture were studied. Dermal architecture was evaluated using a recently developed laser scatter technique. All collagen matrices showed a tendency to reduce wound contraction, compared with control wounds; elastin- and fibronectin-treated matrices showed significantly less contraction than control wounds. Only the addition of elastin had a clear beneficial effect on dermal architecture; collagen bundles were more randomly organized, compared with control wounds, and wounds treated with collagen matrices coated with fibronectin or hyaluronic acid, or without coating. We conclude that the punch biopsy wound model provides important information on dermal regeneration in humans. Native collagen matrices with elastin contributed to dermal regeneration and reduced wound contraction, in contrast with matrices coated with fibronectin or hyaluronic acid, or without coating. Future clinical studies of large-area, full-thickness wounds will be required to establish their clinical relevance for leg ulcer and burn treatment.

Aged↗
PubMed1995

A new psoralen-containing gel for topical PUVA therapy: development, and treatment results in patients with palmoplantar and plaque-type psoriasis, and hyperkeratotic eczema.

Topical photochemotherapy with psoralen and its derivatives 4,5',8-trimethylpsoralen (TMP) and 8-methoxypsoralen (8-MOP), with UVA irradiation, was evaluated with regard to minimum phototoxic dose, concentration, timing of UVA irradiation and systemic and local side-effects, in healthy volunteers. Psoralen (0.005%) in aqueous gel was found to be superior to TMP and 8-MOP in aqueous gel. No hyperpigmentation was seen after topical PUVA treatment with psoralen in aqueous gel. Patients with plaque-type psoriasis (n = 7), palmoplantar psoriasis (n = 7) and hyperkeratotic eczema (n = 2) were treated. Topical PUVA therapy was effective in most psoriasis patients, without the occurrence of local or systemic side-effects. Moreover, hyperkeratotic eczema patients who did not respond to conventional therapy showed partial remission. These results indicate that topical PUVA therapy with psoralen in aqueous gel is a useful therapeutic modality for treatment of psoriasis patients, and patients with recalcitrant dermatoses such as palmoplantar psoriasis and hyperkeratotic eczema.

Eczema↗
PubMed1995

Some aspects of melanin formation of melanocytes cultured on collagen-coated microcarrier beads.

Melanocytes cultured on collagen-coated Cytodex 3 microcarrier Sephadex beads caused remarkable pigmentation of the beads during the period of culture when optimal density was reached. Electron microscopy of melanocytes on the microcarriers revealed that the cells and their dendrites invaginate into the microcarrier surface layer. Removal of the cells by trypsinization showed that some pigment granules were left on the carrier surface and within the cavities present on the microcarrier surface. In order to investigate whether the pigmentation of the microcarriers could be a result of indole intermediates of melanogenesis present in the culture medium, extracts were studied by gas chromatography/mass spectrometry for the presence of these compounds. Two compounds (5,6-dihydroxyindole-2-carboxylic acid and 6-hydroxy-5-methoxyindole-2-carboxylic acid) so far have been identified in the medium extracts. Results indicate that microcarrier culture of melanocytes can serve as an interesting model for electron microscopy studies of melanocytes with regard to pigmentation and cell attachment.

Cell Adhesion↗
PubMed1995

Stimulation of cultured melanocytes in medium containing a serum substitute: Ultroser-G.

Melanocyte cultures were established and maintained routinely in Ham's F-10 medium containing 12-O-tetradecanoyl-phorbol-13-acetate (TPA), isobutylmethylxanthine (IBMX), cholera toxin (CT) and fetal calf serum (FCS). Three serum substitutes (Ultroser-G, Nutridoma-Hu and Nutricyte-H) were tested in order to obtain a medium without FCS having a more constant composition. Melanocyte proliferation was examined in long-term culture experiments by in situ cell counts at different periods of time. Only with Ultroser-G (1-2%) was the proliferation of melanocytes maintained without both FCS and CT, whereas the addition of the other two serum substitutes resulted in stabilization of melanocyte densities in the cultures up to 28 days. In the medium containing 1% Ultroser-G and IBMX without TPA minimal or no increases in melanocyte density were found. Addition of basic fibroblast growth factor (bFGF, 1 ng/ml) to the medium without TPA resulted in a partial restimulation of growth in different experiments. In this system with 1% Ultroser-G and 1 ng/ml bFGF, IBMX could also be replaced by other factors (dbcAMP, LTC4 and a purified form of alpha-melanocyte stimulating hormone). The culture medium with 1% Ultroser-G containing TPA and IBMX is now used for routine melanocyte culture. In this medium TPA/IBMX can easily be replaced by bFGF/dbcAMP with optimal growth stimulation. The combination bFGF/alpha-MSH and other more physiological stimulators offers an alternative to study responses of melanocytes in culture with respect to proliferation, metabolism, and phenotype.

1-Methyl-3-isobutylxanthine↗