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W Westerhof

Publications and source records attributed to W Westerhof.

At least 37 records · Page 2Linked to original sources

The development of guidelines for the treatment of vitiligo. Clinical Epidemiology Unit of the Istituto Dermopatico dell'Immacolata-Istituto di Recovero e Cura a Carattere Scientifico (IDI-IRCCS) and the Archives of Dermatology.

OBJECTIVE: To develop and introduce evidence-based guidelines for the treatment of vitiligo in children and in adults. PATIENTS AND SETTING: Patients, residents, and dermatologists from the Department of Dermatology, Academic Medical Center, University of Amsterdam, and the Netherlands Institute for Pigmentary Disorders in Amsterdam. DESIGN: Scientific evidence obtained from 3 systematic reviews of the literature was combined with the results of 2 questionnaires and interviews of potential users of the guidelines, 3 internal expert meetings, and 1 local expert meeting, during which preliminary guidelines were presented and commented on. A final version of the guidelines was synthesized and disseminated among potential users. Six months after the introduction of these guidelines, their use was evaluated. RESULTS: Before the development of the guidelines, there was no uniformity in treatment selection, and there was a variability in estimates of treatment outcome. The metaanalysis showed class 3 corticosteroids and narrowband UV-B to be the most effective and safest therapies for localized and for generalized vitiligo, respectively. From another systematic review, it could be concluded that patients with segmental, stable, or lip-tip vitiligo could be successfully treated with most autologous transplantation methods. For vitiligo universalis, results of the systematic review showed that depigmentation using monobenzone or a Q-switched ruby laser was equally effective. The final version of the guidelines consisted of a treatment scheme together with detailed treatment protocols. Implementation of the guidelines was evaluated in 5 physicians. After the introduction of these guidelines, they were followed in most adult cases with vitiligo (71% of patients with localized vitiligo, 82% with generalized vitiligo, 100% with stable or segmental vitiligo, and 80% with universal vitiligo). In children with vitiligo, the physicians adhered to the guidelines for 52% of the cases. CONCLUSIONS: Guidelines for the treatment of vitiligo can be successfully developed and disseminated for daily clinical practice. The results of the implementation of these guidelines should be confirmed in other centers involving more clinicians.

Adrenal Cortex Hormones↗

Association of the Köbner phenomenon with disease activity and therapeutic responsiveness in vitiligo vulgaris.

OBJECTIVE: To investigate the association between the experimentally induced Kobner phenomenon (KP-e) and the Kobner phenomenon by history (KP-h), disease activity, and therapeutic responsiveness in vitiligo vulgaris. DESIGN: Cohort study. SETTING: An outpatient clinic. PATIENTS: Sixty-one consecutive patients with vitiligo vulgaris. INTERVENTION: Three months after a standardized epidermodermal injury was induced, the KP-e was evaluated. For 1 year, UV-B (311 nm) therapy or topical fluticasone propionate plus UV-A therapy was given, depending on the severity of depigmentation. MAIN OUTCOME MEASURES: The presence or absence of the KP-e and the KP-h disease activity as scored on a 6-point scale from -1 to +4 (vitiligo disease activity [VIDA] score) and therapy-induced repigmentation grade. RESULTS: Nineteen (31%) of the patients had a positive KP-h, whereas 37 (61%) showed a positive KP-e (P<.001). The VIDA score did not always predict a positive KP-e, although patients with a positive KP-e had a higher mean VIDA score (VIDA score of 1.6) than did patients with a negative KP-e (VIDA score of 0.5) (P<.001). The responsiveness to UV-B (311 nm) therapy among KP-e-positive or KP-e-negative patients was not significantly different (P=.66). However, KP-e-positive patients who were treated with fluticasone propionate plus UV-A showed a better response than did KP-e-negative patients (P=.01). Among patients responding to both therapies, VIDA scores were significantly decreased (P<.001) compared with VIDA scores before therapy. CONCLUSION: The KP-e may function well as a clinical factor to assess present disease activity and may also predict the responsiveness to fluticasone propionate plus UV-A therapy but not to UV-B (311 nm) therapy.

Administration, Topical↗

Left-right comparison study of the combination of fluticasone propionate and UV-A vs. either fluticasone propionate or UV-A alone for the long-term treatment of vitiligo.

OBJECTIVE: To compare the efficacy and safety of using a combination of fluticasone propionate (FP) and UV-A with that of either drug used alone in the long-term treatment of vitiligo. DESIGN: Prospective, randomized, controlled, left-right comparison study. Repigmentation was judged by a single dermatologist (L.N.-K.) and skin thickness was scored by a pathologist (using biopsy samples), a dermatologist (L.N.-K.) (visually), and patients (using a standard questionnaire). SETTING: Netherlands Institute for Pigmentary Disorders, Amsterdam. PATIENTS: Patients with lesions on arms, legs, and trunk were treated on 2 symmetrical lesions for 9 months with FP alone and a combination of FP and UV-A (FP group) or with UV-A alone and a combination of FP and UV-A (UV-A group). Fluticasone propionate cream was applied once daily at about bedtime, and UV-A (10 J/cm2) exposure was twice a week. Patients attended the clinic at 3-month intervals. RESULTS: One hundred thirty-five patients were included, 96 of whom were evaluable after 9 months. Patients not reaching the end point withdrew because of insufficient repigmentation (n = 23), decreased motivation (n = 11), or protocol violations (n = 5). No patient (irrespective of whether they withdrew) experienced any adverse effects. The FP and UV-A groups were comparable with respect to sex, age, and location of lesions. On average, combination treatment was 3 times more effective than either UV-A or FP treatment alone. In the FP group, no atrophy was seen after 9 months with either treatment. In the UV-A group, a little atrophy was detected twice: as well during UV-A treatment alone as during combination treatment. CONCLUSIONS: Combination treatment with FP and UV-A is much more effective in reaching complete repigmentation than are FP and UV-A used alone, but large inter-individual differences occur. Fluticasone propionate, UV-A, and a combination of FP and UV-A seem to be safe for long-term treatment of vitiligo.

Adolescent↗

Management of vitiligo. Results of a questionnaire among dermatologists in The Netherlands.

BACKGROUND: Several therapeutic options are available for the treatment of vitiligo. Concern exists that there is no uniform approach towards the management of vitiligo among Dutch dermatologists. METHODS: A written survey concerning the management of vitiligo was sent to 332 dermatologists in The Netherlands. RESULTS: The response rate was 86%. "Giving information and reassurance concerning the nature of disease" was regarded by most dermatologists (68%) as being the most important goal in the management of vitiligo. Only 16% of the dermatologists aimed for active treatment in vitiligo. The reported therapy choices in children resembled those of adults, except that slightly more dermatologists did not prescribe active therapy in children. Nine different therapeutic modalities were mentioned as first choice therapies. Topical corticosteroids were indicated by most dermatologists as first choice therapy (241 out of 266, i.e. 91%); however, only 2% indicated that 50% or more of the patients achieved a successful treatment; 66% found that less than 25% of the patients were successfully treated with topical corticosteroids. Only 15% of the respondents reported that 50% or more of the patients were treated successfully with narrow-band UVB. The observed response profile to broad-band UVB therapy was found to be comparable with that of narrow-band UVB. The classical therapy with oral psoralen plus UVA (PUVA) was prescribed as first choice therapy by only 12% (32 out of 266) of the dermatologists. Only 6% of these respondents observed that 50% or more of the patients achieved successful therapy using oral PUVA. The recommended maximum treatment duration for topical corticosteroids, oral PUVA, and UVB therapy was found to vary from 3 to 12 months. CONCLUSIONS: Most dermatologists in The Netherlands do not offer active treatment in vitiligo, probably because the estimated effectiveness of (nonsurgical) repigmentation therapy is low. In cases where treatment is prescribed, there appears to be no consensus on the choice of therapies and treatment strategies. The development of practice guidelines may be helpful in reducing inappropriate care and improving treatment outcome.

Administration, Topical↗

Nonsurgical repigmentation therapies in vitiligo. Meta-analysis of the literature.

OBJECTIVE: To assess the effectiveness and safety of nonsurgical repigmentation therapies in localized and generalized vitiligo by means of a meta-analysis. DATA SOURCES: Computerized searches of bibliographic databases, a complementary manual literature search, and contacts with researchers and pharmaceutical firms. STUDY SELECTION: Predefined selection criteria were applied to both randomized and nonrandomized controlled trials. DATA EXTRACTION: Two investigators independently assessed the articles for inclusion. When there was a disagreement, a third investigator was consulted. DATA SYNTHESIS: Sixty-three studies were found on therapies for localized vitiligo. Of these, 10 of 11 randomized controlled trials and 29 of 110 patient series were included. One hundred seventeen studies on therapies for generalized vitiligo were found. Of these, 10 of 22 randomized controlled trials and 46 of 231 patient series were included. Among randomized controlled trials on localized vitiligo, the pooled odds ratio vs placebo was significant for topical class 3 corticosteroids (14.32; 95% confidence interval [CI], 2.45-83.72). In the patient series, topical class 3 and class 4 corticosteroids carried the highest mean success rates (56% [95% CI, 50%-62%] and 55% [95% CI, 49%-61%], respectively). Side effects were reported mostly with topical psoralen and intralesional and class 4 corticosteroids. In the randomized controlled trials on generalized vitiligo, the odds ratio vs placebo was significant for oral methoxsalen plus sunlight (23.37; 95% CI, 1.33-409.93), oral psoralen plus sunlight (19.87; 95% CI, 2.37-166.32), and oral trioxsalen plus sunlight (3.75; 95% CI, 1.24-11.29). In the series, the highest mean success rates were achieved with narrowband UV-B (63%; 95% CI, 50%-76%), broadband UV-B (57%; 95% CI, 29%-82%), and oral methoxsalen plus UV-A therapy (51%; 95% CI, 46%-56%). Oral methoxsalen plus UV-A was associated with the highest rates of side effects. No side effects were reported with UV-B therapy. CONCLUSIONS: Class 3 corticosteroids and UV-B therapy are the most effective and safest therapies for localized and for generalized vitiligo, respectively.

Humans↗

A systematic review of autologous transplantation methods in vitiligo.

OBJECTIVE: A systematic review of the effectiveness, safety, and applicability of autologous transplantation methods in vitiligo. DATA SOURCES: Computerized searches of bibliographical databases, a complementary manual literature search, and contacts with researchers and pharmaceutical firms. STUDY SELECTION: Predefined selection criteria were applied to all studies found. DATA EXTRACTION: Two investigators independently assessed the articles for inclusion. When there was a disagreement, a third investigator was consulted. DATA SYNTHESIS: Sixty-three studies were found, of which 16 reported on minigrafting, 13 on split-thickness grafting, 15 on grafting of epidermal blisters, 17 on grafting of cultured melanocytes, and 2 on grafting of noncultured epidermal suspension. Of these, 39 patient series were included. The highest mean success rates (87%) were achieved with split-skin grafting (95% confidence interval, 82%-91%), and epidermal blister grafting (87%) (95% confidence interval, 83%-90%). The mean success rate of 5 culturing techniques varied from 13% to 53%. However, in 4 of the 5 culturing methods, fewer than 20 patients were studied. Minigrafting had the highest rates of adverse effects but was the easiest, fastest, and least expensive method. CONCLUSIONS: Because no controlled trials were included, treatment recommendations should be formulated with caution. Split-thickness and epidermal blister grafting can be recommended as the most effective and safest techniques. No definite conclusions can be drawn about the effectiveness of culturing techniques because only a small number of patients have been studied. The choice of method also depends on certain disease characteristics and the availability of specialized personnel and equipment.

Humans↗

Quantitative and objective evaluation of wound debriding properties of collagenase and fibrinolysin/desoxyribonuclease in a necrotic ulcer animal model.

Proteolytic enzymes have been used for wound debridement for many years. The two enzymes most widely used in Europe are fibrinolysin/desoxyribonuclease and collagenase. Despite their frequent use, very few placebo-controlled studies comparing the enzymes with vehiculum only, or with each other, are available. In a specially developed necrotic ulcer animal model, combined with a computer image analysis technique to measure necrotic and total wound surface areas quantitatively, we assessed the wound-cleansing properties of fibrinolysin/DNase oleogel, collagenase ointment, saline-soaked gauze control treatment, and new galenic formulations of collagenase, including placebos. The average relative area of necrotic tissue present in the wound after 1 week was 31% for collagenase ointment and 56% for fibrinolysin/DNAse oleogel (P = 0.0037). Collagenase gel was significantly (P = 0.0007) better in removing necrosis than placebo (gel only). Fibrinolysin/DNAse was not significantly more effective than the three placebo or control treatments (placebo film, placebo gel, saline-soaked gauzes). We conclude that collagenase is a suitable enzyme for wound debridement, but we were not able to detect clinical efficacy of fibrinolysin/DNAse in this model.

Animals↗

Relative contributions of decay accelerating factor (DAF), membrane cofactor protein (MCP) and CD59 in the protection of melanocytes from homologous complement.

Complement regulatory molecules, membrane cofactor protein (MCP), decay accelerating factor (DAF) and CD59, protect body cells from autologous complement. They have wide tissue distribution but nothing is known about the expression of these molecules on human melanocytes. Since melanocytes are lysed in the lesional skin of patients with a depigmentary disorder vitiligo, it is important to compare the protection offered by complement regulatory molecules to melanocytes present in normal and vitiligo epidermis, against autologous complement. From this point of view, we investigated the differential expression of MCP, DAF and CD59 on normal cultured human melanocytes and assessed their individual contribution in the protection of these cells against complement-mediated damage. Flow cytometric analysis showed that MCP and DAF but not CD59 were expressed on cultured melanocytes. When heat inactivated sera of patients with vitiligo were used as a source of anti-melanocyte antibody to sensitize melanocytes, and guinea pig serum (GpS) or normal human serum (NHS) as a source of complement, GpS was found to be more effective in causing the lysis of melanocytes than NHS. When melanocytes were sensitized with autoantibody as well as F(ab')2 fragment of either anti-MCP or anti-DAF and subsequently incubated with NHS or GpS, both antibody fragments increased the killing of melanocytes by NHS as well as by GpS. F(ab')2 fragment of anti-DAF was much more effective in causing enhancement of lysis than that of anti-MCP. Thus, cultured normal human melanocytes express functionally active MCP and DAF but not CD59. Contribution of DAF in protecting melanocytes against complement attack was much more than that of MCP.

CD55 Antigens↗

Repigmentation of leucodermic defects in piebaldism by dermabrasion and thin split-thickness skin grafting in combination with minigrafting.

The depigmented skin areas in piebaldism are unresponsive to medical or light treatment. In 12 adult patients (eight women and four men), a method using dermabrasion and thin split-skin grafts was applied initially. Residual leucodermic areas were subsequently treated using a minigrafting method. Additional irradiation with ultraviolet A (10 J/cm2) was performed to enhance melanocyte migration. This combined surgical therapy led to 95-100% repigmentation of the leucodermic defects. A perfect colour match with the surrounding non-lesional skin was achieved in all cases. Complications were minor and easy to correct. Dermabrasion and split-skin grafting followed by minigrafting should be considered as the first choice of therapy in piebaldism.

Adult↗

[Vitiligo].

Vitiligo is a disorder in which, owing to disappearance of melanocytes in the skin, sharply delimited, symmetrically arranged white patches develop. The condition occurs in 1-2% of the population, mostly between the ages of 10 and 30 years, and as often in males as in females. The course is usually progressive with periods of stability. A number of autoimmune diseases and dermatoses coincide with vitiligo. The cause of vitiligo is unknown. Hereditary factors, autoimmunization, neurological disorders and autodestruction have been hypothesized. Repigmentation therapy consists of photo(chemo)therapy use of corticosteroids, and transplantation of pigment cells. For patients in whom this fails and with more than 80% cutaneous involvement, total depigmentation therapy could be considered.

Adolescent↗

[Effective removal of certain skin pigment spots (lentigines) using the Q-switched ruby laser].

OBJECTIVE: To determine the results of treatment of lentigines with the so-called Q-switched ruby laser (QSRL). DESIGN: Descriptive. SETTING: Netherlands Institute for Pigment Disorders. Amsterdam, the Netherlands. METHOD: In 15 patients (nine women and six men), QSRL treatment was applied to solar lentigines (to patients), labial lentigines (2), segmental lentigines (2) and lentigo simplex (1): The light energy ranged from 3 to 10 J/sq.cm. RESULTS: In 11 of 15 patients, one treatment session sufficed to remove the lesion completely. Acute side effects were slight and transient. Six months after the treatment, none of the patients showed recurrences or scar formation. No hypo- or depigmentations were seen. CONCLUSION: In the cases described. QSRL is a successful treatment for lentigines. For lesions of this nature. QSRL is to be preferred above conventional forms of therapy, such as cryotherapy, chemical peeling and abrasion.

Adolescent↗

Effect of nitric oxide on the adhesion of human melanocytes to extracellular matrix components.

The aim of the present study was to explore whether nitric oxide (NO) interferes with the attachment of human melanocytes to the extracellular matrix (ECM) components. Consequently, the effects have been investigated of the NO-releasing compounds 3-morpholino-sydnonimine (SIN-1) and S-nitroso-glutathione (GSNO) on the in vitro adhesion of human melanocytic cells to fibronectin. The NO donors induced a concentration-dependent reduction in the adhesion of both 51CrO4(2-)-labelled melanocytes and melanoma cells to fibronectin. Pigmented M14 melanoma cells were more susceptible to the effect of SIN-1 (half-maximal inhibiting effect at about 0.5 mM) than normal human melanocytes and also than the non-pigmented melanoma cells Mel57 (half-maximal inhibiting effects between 0.9 and 2 mM). This effect of SIN-1 also appeared to be related to the melanin content of normal melanocytes, whereas GSNO was significantly less active. Both flow cytometric analysis and immunocytochemical staining showed expression of neuronal NO synthase in all cell lines. The results of this study suggest that aberrant in vivo production of NO during infection and inflammation may contribute to loss of melanocytes in, for example, vitiligo, by reducing de novo attachment of melanocytes to the ECM. These findings could also be important for understanding the process of metastasis.

Cell Adhesion↗

Generation of a human melanocyte cell line by introduction of HPV16 E6 and E7 genes.

Availability of a standard human melanocyte cell line with unlimited growth potential and otherwise normal melanocytic properties will greatly facilitate research in melanocyte biology and in vitro studies on the etiology of pigmentary disorders and melanoma. Using a retroviral vector, E6 and E7 open reading frames of human papilloma virus type 16 (HPV 16) have been introduced into cultured normal human melanocytes. Cells selected by increased resistance to geneticin conveyed by the vector and expressing E6E7 mRNA have been cloned to ensure genetic homogeneity. Since their establishment as primary cells, cloned PIG1 cells have undergone more than twice the amount of population doublings of senescent parental cells. Moreover, in passage numbers when parental cells had become senescent, proliferation of clonal cells was retained at levels exceeding those of normal human melanocytes in third passage by 100%. Further characterization has revealed that the cells remain dependent on tetradecanoyl phorbol 13-acetate (TPA) for growth and do not proliferate in soft agar nor form tumors in nude mice. The antigenic profile of the cells was slightly altered as compared to parental cells, but was incomparable to that of M14 melanoma cells. Importantly, PIG1 cells contain more melanin pigment than parental cells.

Animals↗

In vitro tissue-digesting properties of krill enzymes compared with fibrinolysin/DNAse, papain and placebo.

Wound debridement, the removal of necrotic tissue, can be achieved with proteolytic enzymes. Recently, a new multi-enzyme preparation, krill enzyme, isolated from Antarctic shrimp-like organisms (Euphausia superba), was reported to possess powerful proteolytic activity towards protein substrates. In this paper, we study the in vitro digestive properties of krill enzymes towards whole tissue, compared with placebo, papain, and fibrinolysin/DNAse. Freshly obtained skin specimens were exposed for 3 days to krill enzymes (3; 0.6 and 0.06 U/ml), papain (120; 60; 6 and 0.6 U/ml), fibrinolysin/DNAse (2.5/1500 E and 1/600 E), and phosphate-buffered saline control solution. Tissue digestion was estimated by measuring wet wt, dry wt, and histological examination. After 72 hr of exposure to 3 U/ml krill enzymes, the dry wt of the specimens was reduced to 2.7% +/- 1.9 (SEM, n = 5), compared with 31.0% +/- 2.7 for placebo, 25.7% +/- 2.5 for 120 U/ml papain, and 24.5% +/- 3.3 for 2.5/1500 E/ml fibrinolysin/DNAse. The differences between krill enzymes and fibrinolysin/DNAse, papain, and control solution were statistically significant (p < 0.007). These data suggest that krill enzymes are more active than other commonly available proteolytic agents used for wound debridement.

Animals↗

Tenascin is overexpressed in vitiligo lesional skin and inhibits melanocyte adhesion.

The aetiology of vitiligo remains obscure. In this study, the role of integrins in the observed inability of melanocytes to repopulate lesional skin was investigated. Antibodies directed to alpha 2, alpha 3, alpha 5, alpha v, alpha 6, beta 1 and beta 3 integrin subunits were used. Immunohistology revealed no marked differences in the overall levels of expression of integrins between control, non-lesional perilesional or lesional skin. Moreover, no differences were noted in the level of expression of integrins or the adhesive capacity between cultured control cells derived from three separate donors and vitiligo-derived melanocytes from two donors. Rather, it was clearly observed that towards the lesion, vitiligo skin contains increasing amounts of tenascin in the basal membrane and papillary dermis in five patients employing T2H5 antihuman tenascin antibody. The anti-adhesive effect observed in vitro for this extracellular matrix molecule using normal melanocytes may contribute to loss of pigment cells in vitiligo or to ineffective repopulation of the lesions.

Adult↗