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Biomedical subjects

B J Vermeer

Publications and source records attributed to B J Vermeer.

At least 19 recordsLinked to original sources
PubMed1997

Melanogenesis in transfected fibroblasts induces lysosomal activation.

Normal melanosome biogenesis requires the association of structural proteins with tyrosinase. 3T3 Swiss fibroblasts transfected with mouse tyrosinase cDNA (line 13.4, clone c) are a unique system in which melanogenesis takes place in the absence of melanosomal structural proteins. Our study confirmed that transfected fibroblasts displayed tyrosinase activity and some of them produced pigment granules. In the absence of melanosomal structural proteins the granules failed both to show a typical ultrastructure and to undergo the usual melanosome ontogenesis. The differentiating agent--dimethyl sulfoxide--increased phaeomelanin production. Pigment was localized in membrane-bound vesicles which were identified as lysosomes by means of immunogold electron microscopy. Cell line 13.4 had higher levels of lysosomal enzymes (beta-hexosaminidase, alpha-mannosidase) than both parental 3T3 cells and clone pKG4 (fibroblasts transfected with the G418 resistance plasmid). Melanosomal proteins act as scavengers of toxic products of melanogenesis, and our results suggest that in their absence cells may employ an alternative mechanism to sequester injurious products.

3T3 Cells↗
PubMed1997

Characterization of interleukin-1 alpha-induced melanoma cell motility: inhibition by type I and type II receptor-blocking monoclonal antibodies.

Interleukin-1 alpha (IL-1 alpha) induces cell motility in a variety of benign cell types and in some but not all malignant cell lines in vitro. This study characterizes the IL-1 alpha-induced motility of an aggressive human melanoma cell line that expresses both type I and type II IL-1 receptors. We tested the effect of monoclonal antibodies including function-blocking moAbs against the type I and type II IL-1 receptors on melanoma cell motility to determine which receptor is involved in signal transduction of IL-1 alpha-induced melanoma cell motility. IL-1 alpha significantly increases MM-RU melanoma cell migration in a dose-dependent manner using modified Boyden chamber assays at concentrations 10 to 100 times less than concentrations that significantly inhibit cell growth. Computer-assisted time-lapse image analysis reveals that the motility is inhibited in a dose-dependent manner by neutralizing antibodies against IL-1 alpha. Function-blocking monoclonal antibodies against either type I or type II IL-1 receptors show a significant inhibition of cytokine-induced enhanced cell migration. When both the anti-IL-1 receptor antibodies are added together, the motility-response is completely blocked to control levels. Taken together the data indicate that the IL-1 alpha-induced motility of MM-RU melanoma cells is mediated through both type I and type II IL-1 receptors. The significant inhibition of motility by neutralizing IL-1 alpha or blocking either one or both of the IL-1 receptors indicates an integration of IL-1-induced signals in the induction of melanoma cell migration.

Antibodies, Blocking↗
PubMed1997

Relation between HLA antigens and skin cancer in renal transplant recipients in Queensland, Australia.

On the basis of previous studies that showed a negative association between HLA-A11 and skin cancer in renal transplant recipients and a positive association with HLA-B27 and HLA-DR7, we performed a study in Queensland with 1098 recipients to address the question of whether the same associations could be found. The influence of HLA mismatching and HLA homozygosity on the risk of skin cancer was also studied. In contrast to earlier studies, HLA-A11 was associated with an increased risk of skin cancer. On the other hand, we confirmed that the HLA-B27 antigen was associated with the development of skin cancer, but only when the development of basal cell carcinomas alone was considered, and we confirmed that there is a weak but not statistically significant association with HLA-DR7. No association between HLA mismatching or HLA homozygosity and the development of skin cancer was observed. Environmental factors such as different levels of exposure to sunlight and infection with human papillomaviruses are factors that are most likely to be involved. We hypothesize that human papillomavirus-induced antigens prevail in the skin cancers in the recipients living in the Netherlands, whereas antigens induced by solar radiation, the so-called "photo-antigens," may be more common in the skin cancers of the recipients living in Queensland. Exposure to sunlight can also induce immunologic unresponsiveness, and excessive exposure to sunlight in Australia may, therefore, simply override the risk factors that are important in countries with a more temperate climate.

Basal Cell Carcinoma↗
PubMed1997

Detection of human papillomavirus DNA in plucked hairs from renal transplant recipients and healthy volunteers.

We have previously detected a group of human papillomaviruses originally found in skin lesions of epidermodysplasia verruciformis (EV) patients in skin cancers from renal transplant recipients and from non-immunosuppressed patients. The reservoir of EV-HPVs is still unknown. In the current study we investigated whether EV-HPV DNA can be detected in plucked hairs from renal transplant recipients and healthy volunteers. Hairs were plucked from eyebrows, scalp, arms, and/or legs and DNA was subsequently isolated. To detect EV-HPV, we used nested PCR with degenerate primers located in the HPV L1 open reading frame. HPV DNA was detected in hairs from one or more sites in all 26 renal transplant recipients tested. Forty-five of 49 samples (92%) from these 26 patients were positive. The HPV type was successfully determined by sequencing in 38 samples, and all types belonged to the EV-HPVs. In ten of 22 healthy volunteers (45%), EV-HPV DNA was also detected in hairs from one or more sites. Twenty of 38 samples (53%) were positive, of which 17 samples were typed as EV-HPV types. These findings indicate that EV-HPV is subclinically present in the skin of the general population. Immunosuppression may lead to activation of the virus, explaining the finding that the apparent prevalence of EV-HPV in plucked hairs from renal transplant patients is higher than in those from the volunteers. If a dose-response situation exists for the carcinogenic potential of HPV infection, this finding may be relevant to the increased risk of skin cancer in this group of patients.

Arm↗
PubMed1997

Differential suppression of the human mixed epidermal cell lymphocyte reaction (MECLR) and mixed lymphocyte reaction (MLR) by cis-urocanic acid.

Cis-urocanic acid (UCA), formed in the stratum corneum by UV irradiation of trans-UCA has been proposed as a mediator of UV-induced immunosuppression in the skin. In this study, we examined the in vitro effect of cis-UCA (6-100 micrograms/mL) on the human mixed lymphocyte reaction (MLR) and the mixed epidermal cell lymphocyte reaction (MECLR). Addition of cis-UCA (purified or in a mixture with trans-UCA) did not affect the MLR but was able to induce a 20% suppression of the MECLR responses. Because this effect of cis-UCA on the MECLR was not as strong as could be expected from previous in vivo results, we designed a set of experiments in order to enhance the in vitro immunosuppressive capacity of cis-UCA. Firstly, we preincubated epidermal cells with UCA (50 micrograms/mL). for 3 or 6 days before culture in the MECLR because in vivo repeated UV exposure can lead to a photostationary state, where cis-UCA may be present for several weeks. This pretreatment with cis-UCA resulted in a maximal decrease of the MECLR response of 27%, whereas trans-UCA had no effect. Secondly, we investigated whether UVB irradiation of epidermal cells could make cells more sensitive to cis-UCA. However, addition of trans- or cis-UCA did not potentiate the reduced alloactivating capacity of UVB-irradiated cells. Finally, we examined the possibility of a synergistic effect of cis-UCA with histamine. Addition of histamine suppressed the MLR and MECLR responses, but neither cis- nor trans-UCA were able to modulate this decrease. We conclude that cis-UCA can partly downregulate the human MECLR but not the MLR. The mechanism involved in this differential downregulation is not known. In this respect it is striking that cis-UCA dose not potentiate the UVB- or histamine-induced suppression of the MECLR.

Cells, Cultured↗
PubMed1997

In situ action spectra suggest that DNA damage is involved in ultraviolet radiation-induced immunosuppression in humans.

The mixed epidermal cell lymphocyte reaction (MECLR) is a commonly used method to study the immunomodulatory effects of UV radiation. The in vitro action spectrum for the MECLR showed that the UV-induced suppression of the MECLR responses is associated with UV-induced DNA damage. To investigate whether in vivo DNA damage also leads to the abrogation of the MECLR, in situ action spectra were made for the MECLR and the induction of thymine dimers (T < > T). Human skin, obtained from plastic surgery, was exposed to monochromatic light of 254, 297, 302 and 312 nm. After irradiation, epidermal cells were isolated and used as stimulator cells in the MECLR or processed for flow cytometric detection of T < > T. On the basis of dose-response curves for each wavelength, the action spectra for suppression of the MECLR and the induction of T < > T were calculated. These spectra showed close similarities, suggesting that, also in situ, UV-induced DNA damage is involved in the UV-induced suppression of the MECLR. Both action spectra showed a small decline from 254 nm to 302 nm, followed by a steep decline to 312 nm. These data show that, in situ, UVC can efficiently induce DNA damage and modulate cutaneous immune responses.

Cells, Cultured↗
PubMed1997

The efficacy of a topical application of terbinafine 1% solution in subjects with pityriasis versicolor: a placebo-controlled study.

A prospective randomised placebo-controlled double-blind study was designed to investigate whether topical terbinafine 1% solution is an effective treatment for subjects with pityriasis versicolor. The intention-to-treat population consisted of 110 subjects. The number of subjects who received terbinafine 1% solution was 76 and the number who received placebo was 34; treatments were given twice a day for 1 week. The primary efficacy variables were categorised at weeks 1, 2, 4 and 8. Eight weeks after the start of therapy, 81% of the subjects using terbinafine solution and 41% of those receiving placebo had a negative mycological examination (p < 0.001). A clinical effect of treatment was recorded in 72% of the subjects using terbinafine 1% solution and 26% of those receiving placebo (p < 0.001). We conclude that terbinafine 1% solution is an effective and safe local treatment modality for pityriasis versicolor.

Administration, Topical↗
PubMed1996

[Terbinafine versus miconazole in patients with tinea pedis].

OBJECTIVE: To compare the efficacy of terbinafine cream during 1 week with the efficacy of miconazole cream during 4 weeks in the treatment of tinea pedis. DESIGN: Prospective randomised double-blind study. SETTING: Department of dermatology, Academic Hospital Leiden, the Netherlands. METHODS: Patients who visited the general practitioner for tinea pedis and who had a positive KOH preparation were treated with terbinafine cream during 1 week and placebo during 3 weeks, or with miconazole cream during 4 weeks. Evaluation was done 1, 2, 3, 4 and 6 weeks after the start of the treatment. Mycological cure was defined as presence of a positive KOH preparation and a positive culture before treatment, and a negative result for both after treatment. Clinical efficacy was defined as mycological cure and presence of at most two minor symptoms (erythema, vesicles, squamae, itching) of the previously most serious skin lesion. Evaluation was done of all patients with a positive KOH preparation and of all patients with a positive KOH and a positive culture. RESULTS: 263 patients were included. Of these 207 had a positive culture; 56 patients had a positive KOH preparation but a negative culture. The group of patients treated with terbinafine and placebo consisted of 129 patients, the miconazole group of 134 patients. Both groups had an equal distribution as to age, sex, race, duration and seriousness of the fungal infection and previous treatment. Mycological cure and clinical efficacy throughout the evaluation were similar in both treatment groups, in both patients with positive KOH preparation and in patients with a positive KOH preparation and a positive culture. After 6 weeks mycological cure was seen in about 95% and clinical efficacy in about 87%. CONCLUSION: In the treatment of tinea pedis local application of terbinafine cream during 1 week is as good as treatment with miconazole cream during 4 weeks.

Adult↗
PubMed1996

Modulation of alpha 4 beta 1 and alpha 5 beta 1 integrin expression: heterogeneous effects of Q-switched ruby, Nd:YAG, and alexandrite lasers on melanoma cells in vitro.

BACKGROUND AND OBJECTIVE: Integrins of the beta 1 family are cellular adhesion molecules that play an important role in cell attachment and migration by interacting with extracellular matrix molecules. Agents such as hormones, cytokines, and ultraviolet radiation have all been shown to have an integrin modulating potential. The present study indicates that radiation of Q-switched lasers is also able to induce transient changes in integrin expression levels on human melanoma cells in vitro. STUDY DESIGN/MATERIALS AND METHODS: Radiation from Q-switched Ruby (694 nm), Alexandrite (755 nm), and Nd:YAG laser (1,064 nm) with fluences comparable to those that are generally used in treating dermatologic lesions were used to irradiate a subconfluent layer of human melanoma cells. After fixed time intervals, the cells were harvested either to analyse the integrin expression by flow cytometry or to investigate changes in cell attachment, spreading, and migration. RESULTS: It was established that all three types of laser were able to cause a significant downregulation of both the alpha 4 and the common beta 1 integrin subunit. The Alexandrite and Ruby lasers also induced a decrease in alpha 5 expression; however, the cells treated with the Nd:YAG laser showed a marked upregulation of the alpha 5 subunit. The expression of the other beta 1 integrin subunits was shown to be unaltered after laser treatment. Downregulation of the alpha 4 upregulation of the alpha 5 integrin subunit expression resulted in, respectively, decreased and increased attachment and spreading on fibronectin, the extracellular matrix ligand for both the alpha 4 beta 1 and alpha 5 beta 1 integrins. Marked upregulation of the alpha 5 subunit also resulted in a higher migration rate. CONCLUSION: Taken together, these results show that nonlethal doses of Q-switched laser radiation are able to induce changes in cellular behavior in vitro by modulating the integrin expression pattern.

Aluminum Oxide↗
PubMed1996

Chronic sun exposure and age are inversely associated with nevi in adult renal transplant recipients.

In 126 adult renal transplant recipients who had survived their transplantation for at least 8 years, we determined whether numbers of nevi and the presence of clinically atypical nevi were related to chronic sun exposure. On the basis of a skin examination, three groups were defined: patients with at least one clinically a typical nevus; patients with only clinically normal nevi: and patients without any nevi. The prevalence odds ratio of having any clinically atypical nevi as compared to having only clinically normal nevi was calculated in a logistic model, in relation to gender, skin type, age, sun exposure, and number of keratotic skin lesions present. Similarly, the prevalence odds ratio of having 30 or more nevi compared to fewer than 30 nevi was calculated. We found an inverse association between chronic sun exposure and age with numbers of nevi in adult renal transplant recipients. The presence of clinically atypical nevi was also inversely associated with chronic sun exposure, but this association disappeared after adjustment for age. We did not observe an association of nevi with the number of keratotic skin lesions, nor with humoral immune responses against human papillomavirus and the presence of certain HLA antigens, which are factors associated with nonmelanoma skin cancer in renal transplant recipients. Chronic sun exposure and age appeared to be strong determinants for decreased numbers of nevi in adult renal transplant recipients. Infection with human papillomaviruses does not appear to play an important role.

Adult↗
PubMed1996

Comet assay demonstrates a higher ultraviolet B sensitivity to DNA damage in dysplastic nevus cells than in common melanocytic nevus cells and foreskin melanocytes.

We used the single cell gel electrophoresis assay (comet assay) to study ultraviolet B (UVB)-induced DNA damage in pigment cells. This assay detects DNA damage, mainly DNA strand breaks and alkali labile sites in the DNA molecule. We studied the effect of biologically relevant doses (comparable to 2-3 MED (minimal erythemal dose) for in vivo irradiated full-thickness skin) of monochromatic UVB light of 302 nm on cultured melanocytes derived from foreskin, common melanocytic nevi, and dysplastic nevi. We were able to demonstrate a linear dose-response relationship between UV dose and the migration coefficient of the comet tail in all three types of pigment cells. Nevus cells originating from dysplastic nevi showed the highest sensitivity to UVB irradiation: 65% higher induction of DNA damage compared to the induction in foreskin melanocytes. Common melanocytic nevus cells were most resistant and showed a 30% lower induction of DNA damage in comparison to foreskin melanocytes. Differences in chromatin structure and cell cycle profile may influence the results of the comet assay. Control experiments with x-ray irradiation, which is well known to produce direct DNA strand breaks via radical formation, revealed only small differences between the three types of melanocytic cells. It is unlikely, therefore, that intrinsic nuclear characteristics may account for the observed differences.

Cell Movement↗
PubMed1996

Attachment, spreading and migration of melanoma cells on vitronectin. The rôle of alpha V beta 3 and alpha V beta 5 integrins.

Recent in situ studies suggest the alpha V beta 3 integrin is a tumour progression marker in melanoma. We analyzed 5 human melanoma cell lines for their expression of the vitronectin binding alpha V beta 3 and alpha V beta 5 integrins using flow cytometry. The role of these receptors in cell attachment, spreading and migration was investigated using attachment assays, video time lapse spreading and migration assays and with function blocking monoclonal antibodies. Cell lines derived from later stages of tumor progression exhibited high levels of alpha V beta 3 expression, whereas no similar correlation with alpha V beta 5 expression was identified. Cell attachment, spreading and migration response on vitronectin correlated well with the expression level of the alpha V beta 3 but not the alpha V beta 5 vitronectin receptor. Blocking of the alpha V beta 3 integrin resulted in a significant decrease in cell attachment, spreading and motility whereas the function blocking antibody against the alpha V beta 5 integrin only inhibited cell attachment in cell lines with the highest level of expression of this integrin. Taken together, our study indicates that the level of expression of the alpha V beta 3 and alpha V beta 5 integrins is heterogeneous in melanoma cell lines and that the alpha V beta 5 integrin, if present, may function only during the initial cell attachment whereas the alpha V beta 3 plays an important role in cell spreading and cell migration as well.

Antibodies, Blocking↗
PubMed1996

Keratinocytes resident in normal human skin constitutively express, at low levels, the intercellular adhesion molecule-1. An in situ immunoelectronmicroscopy study.

The expression of intercellular adhesion molecule-1 (ICAM-1) on keratinocytes (KC) was previously demonstrated in biopsies from various inflammatory skin lesions. KC were, however, found virtually ICAM-1 negative, in normal skin, when the same immunocytochemical techniques were employed. By contrast, epithelial cells resident in different organs constitutively express ICAM-1, albeit weakly. The aim of the present study was to use an immunostaining system more sensitive than the conventional immunocytochemistry, namely the in situ immunogold labelling of ultracryosections, to investigate the constitutive ICAM-1 expression by resting KC in normal skin, in vivo. The semiquantitative analysis performed on 500 resident KC, visualized within tissue ultracryosections of normal human skin, revealed that gold granules were present long the cell membrane in a small percentage (14.6%) of resident KC. The density of gold particles (10 nm sized) observed on the cell surface per KC section was as scarce as 13.72 +/- 4.6 (mean +/- standard deviation), although highly significant when compared with controls (P < 0.005). This indicates the presumably low expression of ICAM-1 moieties on the plasma membrane of this KC subset. This ICAM-1 expression could be important in modulating the trafficking to and from normal epidermis of migrating Langerhans cells and occasional leucocytes. The fact that the ICAM-1 expression on KC in normal skin is limited can be considered favourable, because it can account for the prevention of inappropriate KC/leucocyte interactions in the resting cutaneous environment.

Epidermis↗
PubMed1995

Distribution of HLA class II molecules in epidermal Langerhans cells in situ.

We performed immunoelectron microscopic studies to investigate the expression of HLA class II molecules in Langerhans cells (LC). In the epidermis, LC expressed class II molecules on the plasma membrane of the dendrites, resulting in a class II positive reticulo-epithelial network, but not on the surface of the cell body. In contrast, isolated LC as well as activated LC in situ displayed an even and strong expression of class II molecules on their entire cell surface. Therefore, isolation and/or activation results in redistribution and up-regulation of class II molecules on the cell surface. In addition, double-labeling experiments were carried out with monoclonal antibodies to class II antigens and to LAMP-1, CD63 and alpha-glucosidase, specific markers for organelles of the endosomal/lysosomal system. The results show expression of class II molecules on intracellular, electron-dense vesicular structures, and co-localization of class II molecules and the markers for late endosomes and early lysosomes in human LC in situ. Expression of these markers was not found on Birbeck granules, an LC-specific organelle.

Animals↗
PubMed1995

A comparative study of atypical and melanocytic naevi on the tropical island Curaçao and in The Netherlands.

A cross-sectional study was undertaken in 270 inhabitants of The Netherlands (moderate maritime climate, latitude 51 degrees 5' N-53 degrees 3' N) with skin types I-III and 757 inhabitants of the tropical island Curaçao (latitude 12 degrees 2' N-12 degrees 23' N). The latter group consisted of 282 White individuals (mostly Dutch immigrants) and 475 people with non-White skin types IV, V and VI. All participants underwent total skin examination and melanocytic naevi (MN) and clinically atypical naevi (AN) were noted. There was no statistical difference in the mean number of naevi > or = 2 mm or > or = 5 mm between the Curaçao and The Netherlands White groups, but the mean number of naevi > or = 2 mm and > or = 5 mm was significantly lower in the Curaçao non-White group. We found no obvious differences in mean naevus counts between genders and the various comparable age groups. Furthermore, we found no significant difference in mean crude and mean age-standardized prevalence of (one or more) AN between Whites in The Netherlands and on Curaçao. The Mantel-Haenszel prevalence ratio weighted for age and gender differences of Curaçao Whites vs non-Whites was 5.93 (95% confidence interval 3.9-12.0), demonstrating that AN are significantly less prevalent in darker skin types. In all groups, people with AN had significantly more MN than people without AN. We found a generation-dependent difference in the expression of AN among White inhabitants of The Netherlands and on Curaçao, with a higher prevalence of AN in the younger generation.

Adolescent↗