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Biomedical subjects

Klaus Wolff

Publications and source records attributed to Klaus Wolff.

At least 37 records · Page 2Linked to original sources
PubMed2004

CpG oligonucleotides elicit antitumor responses in a human melanoma NOD/SCID xenotransplantation model.

For patients with advanced malignant melanoma, the 5 y survival rate with current treatment modalities is low. There is an urgent need for more effective therapeutic concepts. One approach with great potential is to stimulate the body's own immune defense to reject cancer cells using CpG oligonucleotides. Distinct oligonucleotides containing nonmethylated cytidine residues in cytidine-guanosine dinucleotides with particular flanking bases (CpG motifs) are capable of eliciting powerful immune stimulation by mimicking infectious disease. We evaluated the in vivo antitumoral effects of CpG oligonucleotides against human malignant melanoma xenografts in NOD/SCID mice. CpG oligonucleotides administered in single peritumoral subcutaneous injections three times per week resulted in elevated plasma levels of interleukin-12 and significant inhibition of the growth of established tumor xenografts by 60% (p<0.016) compared to the saline control. In addition to this a significant invasion of macrophages into tumor xenografts and increased numbers of Langerhans-cell-derived dendritic cells in draining lymph nodes could be observed. Our findings demonstrate the antitumor activity of oligonucleotides containing immune-stimulatory CpG motifs in a xenotransplantation model with absent B, T cells and a lack of natural killer cell function.

Animals↗
PubMed2004

RPE65 of retinal pigment epithelium, a putative receptor molecule for plasma retinol-binding protein, is expressed in human keratinocytes.

Retinoids are important modulators for cell growth and differentiation of normal skin. In plasma, retinol is transported coupled to plasma retinol-binding protein. In this study, we investigated gene and protein expression of RPE65, a putative receptor for plasma retinol-binding protein in human epidermal keratinocytes. We performed real-time PCR analysis to evaluate expression of RPE65 mRNA in proliferating and differentiating keratinocytes. Immunoblotting with anti-RPE65 antibody shows distinct reactivity to a 61-kDa protein. Indirect immunofluorescence on normal human epidermis reveals cell surface labeling of keratinocytes. Laser scan microscopy exhibits colocalization of plasma retinol-binding protein and RPE65 on cultured keratinocytes. Internalization experiments with [3H]retinoic acid-retinol-binding protein complex in the presence and absence of excess of retinol-binding protein indicates receptor-dependent uptake of retinoids. We further show isolation of RPE65 protein by affinity chromatography from lysates of keratinocytes using a retinol-binding protein-matrix gel column. In summary, we demonstrate mRNA and protein expression of RPE65 in epidermal keratinocytes. Colocalization of plasma retinol-binding protein with RPE65 and affinity binding suggest a direct interaction of RPE65 with plasma retinol-binding protein in cultured human keratinocytes that might be involved in retinoid uptake of keratinocytes.

Adult↗
PubMed2004

BRAF kinase gene V599E mutation in growing melanocytic lesions.

Mutations in the BRAF-gene are found in benign and malignant melanocytic lesions, >90% being a V599E mutation. This mutation results in constitutively active kinase function and increased colony formation in vitro. The biological impact of this mutation in vivo is still debated. To address this question, we used our digital epiluminescence image archive and retrospectively selected 49 melanocytic lesions, which did not meet the criteria of melanoma at the initial presentation. Mean 12 months later these lesions were excised because of increased size or changed structure and BRAF(V599E) mutations were analyzed. Among 36 growing lesions, BRAF(V599E) mutations were found in 16 (11 melanomas and 5 nevi). Among 13 lesions with structural changes, BRAF(V599E) mutations were found in 4 (3 melanomas and 1 nevus). Thirty-five randomly selected additional lesions with no changes during follow-up served as controls, all nevi by histology, and two of them showed a BRAF(V599E) mutation. Statistics revealed odds for the presence of the BRAF(V599E) mutation being seven times higher in lesions with structural changes and 13 times higher in growing lesions as compared with lesions without changes. This raises the question if the V599E mutation determines lesions at risk developing into melanoma and if not, what are the mechanisms controlling growth stop in benign lesions?

Adult↗
PubMed2004

Pegylated and conventional interferon-alpha induce comparable transcriptional responses and inhibition of tumor growth in a human melanoma SCID mouse xenotransplantation model.

Interferon-alpha (IFN-alpha) is widely used for the treatment of viral infections and primary cancers. In the present study, we investigated whether the anti-proliferative activity of IFN-alpha is capable of inhibiting melanoma tumor development in the absence of protective immune responses in a severe combined immunodeficiency (SCID) mouse model. Mice treated with either regular (100 microg/3 times per week) or pegylated (300 microg/once weekly) human IFN-alpha 2a showed a marked reduction in tumor weight after 4 wk of treatment. Tumor weight in pegylated and conventional IFN-alpha-treated animals was reduced by 61% and 67%, respectively, as compared to saline control (both p< or =0.01). A decrease of proliferation and an increase of apoptotic tumor cells were observed in IFN-treated tumors. DNA microarrays were applied to analyze transcriptional responses in tumors after 4 wk of treatment and a subset of about 90 genes was differentially expressed. Twenty-four novel and five known interferon-inducible genes were up- and 65 genes downregulated. A direct comparison of IFN-alpha and pegylated IFN-alpha did not reveal any significant differences in tumor growth inhibition indicating that this novel and more stable class of IFN is functionally equivalent. Despite the structural difference between pegylated and conventional IFN-alpha, both agents caused similar transcriptional responses in human melanoma xenotransplants.

Animals↗
PubMed2004

Pimecrolimus for the treatment of inflammatory skin disease.

Pimecrolimus (SDZ ASM 981, Elidel ) is an ascomycin macrolactam derivative and a cell-selective inhibitor of inflammatory cytokines specifically developed to treat inflammatory skin diseases. Pimecrolimus combines high anti-inflammatory activity in the skin with a low potential to impair systemic immune reactions. Multi-centre studies have proved the efficacy and safety of pimecrolimus cream in patients with atopic dermatitis (AD) and confirmed that it is suitable for short-term treatment and long-term management of AD in adults, children and infants as young as 3 months. Topical application in humans is not associated with the atrophogenic side effects observed with corticosteroids. Pimecrolimus blood levels remained consistently low after repeated topical application and no clinically relevant drug-related systemic adverse events have been reported among the 8000 patients treated in clinical trials so far. Short-term, Phase I/II and Phase II trials of pimecrolimus administered orally in psoriasis and AD have shown that this drug is highly effective in a dose-dependent manner in patients with these diseases and has high safety profile. This finding is confirmed by pharmacogenomic blood analysis. Available data thus indicates that pimecrolimus, in both the cream and oral formulations, may represent a new option for the treatment of inflammatory skin diseases.

Administration, Cutaneous↗
PubMed2003

An endogenous retrovirus derived from human melanoma cells.

We show that human melanoma cells produce retrovirus-like particles that exhibit reverse transcriptase activity, package sequences homologous to human endogenous retrovirus K (HERV-K), and contain mature forms of the Gag and Env proteins. We also demonstrate expression of the pol gene and of Gag, Env, and Rec proteins in human melanomas and metastases but not in melanocytes or normal lymph nodes. The data suggest that expression of retroviral genes and production of retroviral particles is activated during development of melanoma.

Base Sequence↗
PubMed2003

The plant lectin wheat germ agglutinin inhibits the binding of pemphigus foliaceus autoantibodies to desmoglein 1 in a majority of patients and prevents pathomechanisms of pemphigus foliaceus in vitro and in vivo.

Pemphigus foliaceus (PF) is a life-threatening autoimmune blistering skin disease caused by pathogenic IgG autoantibodies against desmoglein 1 (dg1), a desmosomal cadherin-type adhesion glycoprotein. Using lectins and glycosidases, we have shown that dg1 displays an N-glycosylation pattern of the complex triantennary type. We have found that lectins and glycosidases interfere with N-bound sugar residues on the amino-terminal ectodomain of dg1 and completely abolish, in vitro, the antigenicity of dg1 in most of the patients' sera. Moreover, in an ex vivo model using punch biopsies from normal human skin, we demonstrate that preincubation of the epidermis in wheat germ agglutinin (WGA) prevents PF autoantibody binding, acantholysis, and subcorneal blistering. In addition, we show that topical treatment with WGA inhibits PF autoantibody binding to keratinocytes in both newborn BALB/c mice and in organotypic human epidermis grafted onto the back of SCID mice. The epidermis of these pretreated animals displays a regular morphology, whereas control animals develop the immunopathologic phenotype of PF. These findings suggest that WGA may interfere with autoantibody binding to dg1, preventing experimental PF without affecting the adhesive function of dg1. Our observations may provide a new approach to the therapy of PF.

Administration, Topical↗
PubMed2003

[Ruptured abdominal aortic aneurysms: status quo after a quarter century of treatment experience].

BACKGROUND: Postoperative mortality rates between 40% and 50% have been invariably reported for the treatment of ruptured abdominal aortic aneurysms (rAAA) over the last 50 years. The aim of this analysis was to investigate which patient subgroups benefit from open surgery and in which subgroups a change of treatment strategies should be considered due to lack of improvement despite optimal patient management. PATIENTS AND METHODS: From 1980 to 2002 a total of 230 patients underwent surgery because of a ruptured AAA. The observation period was divided into 3 intervals to achieve an approximately equal distribution of patients. The effect of the observation period and of baseline parameters on mortality rates were investigated. RESULTS: Between 1980 and 1990, 72 patients were operated with a mortality rate of 38.9% (n = 28). During the second period (1991-1996) surgery was performed in 72 patients with a mortality rate of 40.3% (n = 29). In the third observation interval (1997-2002) 86 patients underwent surgery with an unvaried high mortality rate of 40.7% (n = 35). By applying a logistic regression model including age, gender, modality of rupture, location of cross-clamping and type of operation, only the modality of rupture and the patient's age, which are uncontrollable by the surgeon, could be shown to have a significant impact. CONCLUSION: Summing up these findings, open surgical repair of rAAA only leads to acceptable results when performed in younger patients without supposed comorbidities. Survival appears to be accidental in patients with advanced age and increased prevalence of relevant comorbidities/underlying diseases. Minimally invasive techniques may offer promising treatment options to those patients, as they do in elective interventions.

Adult↗
PubMed2003

Accuracy of computer diagnosis of melanoma: a quantitative meta-analysis.

BACKGROUND: Recent developments in computer technology have raised expectations that fully automated diagnostic instruments will become available to diagnose cutaneous melanoma without the need of human expertise. OBJECTIVES: To critically review the contemporary literature on computer diagnosis of melanoma, evaluate the accuracy of such computer diagnosis, analyze the influence of study characteristics, and compare the accuracy of computer diagnosis of melanoma with human diagnosis. METHODS: Quantitative meta-analysis of published reports. DATA SOURCES: Eligible studies were identified by a MEDLINE search covering the period from January 1991 to March 2002, by manual searches of the reference lists of retrieved articles, and by direct communication with experts. RESULTS: Thirty studies with substantial differences in methodological quality were deemed eligible for meta-analysis. Five of these complied with the predetermined list of "good quality" requirements, but none met all methodological quality requirements. Ten of these studies compared the performance of computer diagnosis with human diagnosis. The diagnostic accuracy achieved with computer diagnosis was statistically not different from that of human diagnosis (log odds ratios, 3.36 vs 3.51; P =.80). The diagnostic performance of the computer diagnosis was better for studies that used dermoscopic images than for studies that used clinical images (log odds ratios, 4.2 vs 3.4; P =.08). Other study characteristics did not significantly influence the accuracy of the computer diagnosis. CONCLUSIONS: The computer diagnosis of melanoma is accurate under experimental conditions, but the practical value of automated diagnostic instruments under real-world conditions is currently unknown. We suggest minimum requirements for methodological quality in future experimental studies or, ideally, randomized controlled trials.

Clinical Trials as Topic↗
PubMed2003

Internalization via plasmalemmal vesicles: a route for antidesmoplakin autoantibodies into cultured human keratinocytes.

Recently, autoantibodies to desmoplakin I and II have been identified in a subset of patients with a severe form of erythema multiforme. These autoantibodies recognize a specific peptide sequence at the carboxy terminal domain of desmoplakin I and II responsible for interaction with keratin filaments. Desmoplakins are major constitutive proteins of the inner dense desmosomal plaque of keratinocytes and are entirely localized within the cells. With the assumption of pathogenecity for circulating autoantibodies, the question arose how antidesmoplakin autoantibodies enter keratinocytes. Utilizing immunhistochemical procedures for cell motility and time kinetic studies at the light- and electron-microscopic level, we found that autoantibodies are bound at the cell surface of cultured human keratinocytes, internalized via plasmalemmal vesicles, and are found consecutively within tubulovesicular structures inside the cells. At the same time, a fraction of antibodies can be detected at the inner dense desmosomal plaques. Immunogold labeling reveals internalization of autoantibodies in small non-coated plasmalemmal vesicles positive for caveolin. These observations indicate that vesicular transport may represent a relevant biological mechanism for antidesmoplakin autoantibodies to enter keratinocytes and allow access to their corresponding antigenic target in vivo.

Autoantibodies↗
PubMed2003

Paclitaxel encapsulated in cationic liposomes diminishes tumor angiogenesis and melanoma growth in a "humanized" SCID mouse model.

Paclitaxel is an alkaloid that inhibits endothelial cell proliferation, motility, and tube formation at nanomolar concentrations. Cationic liposome preparations have been shown to target blood vessels. We wished to explore the possibility that paclitaxel encapsulated in cationic liposomes carries paclitaxel to blood vessels and thereby provides an antiangiogenic effect. We used a humanized SCID mouse melanoma model, which allowed us to analyze tumor growth and tumor angiogenesis in an orthotopic tumor model. Here, human melanoma cells grow on human dermis and are in part nourished by human vessels. We show that paclitaxel encapsulated in liposomes prevents melanoma growth and invasiveness and improves survival of mice. Moreover, liposome-encapsulated paclitaxel reduces vessel density at the interface between the tumor and the human dermis and reduces endothelial cell mitosis to background levels. In contrast, equimolar concentrations of paclitaxel solubilized in Cremophor EL(R) had only insignificant effects on tumor growth and did not reduce the mitotic index of endothelium in vivo, although the antiproliferative effect of solubilized paclitaxel in Cremophor EL(R)in vitro was identical to that seen with liposome-coupled paclitaxel. In conclusion, we present a model of how to exploit cytotoxic effects of compounds to prevent tumor growth by using cationic liposomes for targeting an antiproliferative drug to blood vessels.

Angiogenesis Inhibitors↗
PubMed2003

RasGAP-like protein IQGAP1 is expressed by human keratinocytes and recognized by autoantibodies in association with bullous skin disease.

Autoantibodies in patients with autoimmune bullous skin diseases, such as pemphigus or bullous pemphigoid are of diagnostic value and might play a part in the pathogenic scenario. In this study we present five patients with erythematous plaques, subepidermal blister formation of the skin, and the presence of circulating autoantibodies directed against a so far unrecognized 190 kDa antigen in human keratinocytes. Amino acid sequence analysis identified the protein as IQGAP1, a recently described human Ras GTPase-activating-like protein suspected to act as an effector molecule for Cdc42 and Rac1, members of the Rho small GTPase family and to play a key part in regulating E-cadherin-mediated cell adhesion. The protein is selectively recognized by a monoclonal anti-IQGAP1 antibody on western blots and immunoprecipitates from keratinocyte extracts. Indirect immunofluorescence locates IQGAP1 within individual keratinocytes in a cytoplasmic pattern and along the cell periphery at adhesive sites. Our results demonstrate IQGAP1, a newly described multifunctional protein, to be constitutively expressed in human keratinocytes where it may contribute to the integrity of the epidermal layer. Furthermore, we found autoantibodies reacting with IQGAP1 in patients with bullous skin eruptions most apparently belonging to the spectrum of bullous pemphigoid.

Adult↗
PubMed2003

Mcl-1 antisense therapy chemosensitizes human melanoma in a SCID mouse xenotransplantation model.

It is well established that high expression of the antiapoptotic Bcl-2 family proteins Bcl-2 and Bcl-xL can significantly contribute to chemoresistance in a number of human malignancies. Much less is known about the role the more recently described Bcl-2 family member Mcl-1 might play in tumor biology and resistance to chemotherapy. Using an antisense strategy, we here address this issue in melanoma, a paradigm of a treatment-resistant malignancy. After in vitro proof of principle supporting an antisense mechanism of action with specific reduction of Mcl-1 protein as a consequence of nuclear uptake of the Mcl-1 antisense oligonucleotides employed, antisense and universal control oligonucleotides were administered systemically in combination with dacarbazine in a human melanoma SCID mouse xenotransplantation model. Dacarbazine, available now for more than three decades, still remains the most active single agent for treatment of advanced melanoma. Mcl-1 antisense oligonucleotides specifically reduced target protein expression as well as the apoptotic threshold of melanoma xenotransplants. Combined Mcl-1 antisense oligonucleotide plus dacarbazine treatment resulted in enhanced tumor cell apoptosis and led to a significantly reduced mean tumor weight (mean 0.16 g, 95% confidence interval 0.08-0.26) compared to the tumor weight in universal control oligonucleotide plus dacarbazine treated animals (mean 0.35 g, 95% confidence interval 0.2-0.44) or saline plus dacarbazine treated animals (mean 0.39 g, 95% confidence interval 0.25-0.53). We thus show that Mcl-1 is an important factor contributing to the chemoresistance of human melanoma in vivo. Antisense therapy against the Mcl-1 gene product, possibly in combination with antisense strategies targeting other antiapoptotic Bcl-2 family members, appears to be a rational and promising approach to help overcome treatment resistance of malignant melanoma.

Animals↗
PubMed2003

[Clinical value of a dermatoscopic classification of Clark nevi].

BACKGROUND AND OBJECTIVES: The aim of this study was to evaluate the practical value of the dermatoscopic classification of Clark nevi PATIENTS AND METHODS: Dermatoscopic images of 268 lesions clinically and dermatoscopically diagnosed as Clark nevi were presented to 2 dermatologists without knowledge of the histological diagnosis. The dermatologists evaluated the lesions according to a simplified version of the classification scheme for Clark nevi proposed by Hofmann-Wellenhof and differentiated between 12 different types of Clark nevi. RESULTS: The most common type of Clark nevus was the reticular-homogenous type (n = 64, 23.9%), followed by the globular-homogeneous type (n = 32, 12%) and by the homogenous type (n = 30, 11.2%). The overall inter-rater agreement between the examiners was moderate to good (kappa = 0.58). The highest level of agreement was found for the peripheral hyperpigmented type (kappa = 0.83). Histologically, 17 lesions (6.3%) were diagnosed as melanomas. The frequency of melanoma was highest among the peripheral-hyperpigmented type for one observer and among the homogenous type for the other observer. No melanoma was found among the globular, reticular-globular, and the central-hyperpigmented types. CONCLUSIONS: A dermatoscopic classification of Clark nevi is practically feasible and allows--to some extent--a risk stratification of Clark nevi, which could be useful for clinical management.

Dermoscopy↗
PubMed2003

Dermoscopy of pigmented skin lesions: results of a consensus meeting via the Internet.

BACKGROUND: There is a need for better standardization of the dermoscopic terminology in assessing pigmented skin lesions. OBJECTIVE: The virtual Consensus Net Meeting on Dermoscopy was organized to investigate reproducibility and validity of the various features and diagnostic algorithms. METHODS: Dermoscopic images of 108 lesions were evaluated via the Internet by 40 experienced dermoscopists using a 2-step diagnostic procedure. The first-step algorithm distinguished melanocytic versus nonmelanocytic lesions. The second step in the diagnostic procedure used 4 algorithms (pattern analysis, ABCD rule, Menzies method, and 7-point checklist) to distinguish melanoma versus benign melanocytic lesions. kappa Values, log odds ratios, sensitivity, specificity, and positive likelihood ratios were estimated for all diagnostic algorithms and dermoscopic features. RESULTS: Interobserver agreement was fair to good for all diagnostic methods, but it was poor for the majority of dermoscopic criteria. Intraobserver agreement was good to excellent for all algorithms and features considered. Pattern analysis allowed the best diagnostic performance (positive likelihood ratio: 5.1), whereas alternative algorithms revealed comparable sensitivity but less specificity. Interobserver agreement on management decisions made by dermoscopy was fairly good (mean kappa value: 0.53). CONCLUSION: The virtual Consensus Net Meeting on Dermoscopy represents a valid tool for better standardization of the dermoscopic terminology and, moreover, opens up a new territory for diagnosing and managing pigmented skin lesions.

Algorithms↗