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Biomedical subjects

K Wolff

Publications and source records attributed to K Wolff.

At least 73 records · Page 4Linked to original sources
PubMed1999

Deletions of the region 17p11-13 in advanced melanoma revealed by cytogenetic analysis and fluorescence in situ hybridization.

The significance of the p53 tumour-suppressor gene in the oncogenesis of a variety of malignant tumours has been demonstrated over recent years. However, the role of p53 in human malignant melanoma is still unclear. Therefore, we investigated melanoma metastases from 11 patients cytogenetically and with fluorescence in situ hybridization (FISH) after short-term culture, employing a p53 region-specific probe for 17p13.1 and a probe detecting the centromere of chromosome 17. Furthermore, paraffin-embedded tissue samples from nine of these patients were investigated immunohistochemically for expression of the p53 protein. Deletions of the short arm of chromosome 17 were seen in six melanomas in cytogenetic analysis. With FISH, three malignant melanomas had clones with only one p53-allele and an additional four malignant melanomas showed a reduced number of signals at the p53 tumour-suppressor gene locus compared with signals for the centromeric region of chromosome 17. This was confirmed by immunohistochemistry. Our results suggest that the 17p11-13 region is frequently deleted in malignant melanomas and that p53 or other genes located on this band might contribute to the malignant potential of advanced melanoma.

Chromosome Deletion↗
PubMed1999

A review of biological indicators of illicit drug use, practical considerations and clinical usefulness.

AIMS: To examine a range of biological indicators of illicit drug use, including blood, urine, hair and saliva, addressing both technological and practical issues relating to their application and interpretation. METHODS: The review process involved an examination of key reference texts and literature from the scientific fields of analytical and clinical toxicology. FINDINGS: Urine remains the biological tool of choice for qualitative detection of illicit drug use in a clinical setting, while quantitative accuracy remains strictly the domain of blood. The growing sophistication of laboratory analysis may additionally make possible the routine use of hair sampling which can provide a much longer time frame for assessment. Breath, saliva, sweat or breast milk remain possibilities in the future. CONCLUSIONS: Accurate interpretation of the screening tests within a clinical setting alongside other relevant information remains the key to the usefulness of any test.

Biomarkers↗
PubMed1999

Population pharmacokinetics of methadone in opiate users: characterization of time-dependent changes.

AIMS: Although methadone is widely used to treat opiate dependence, guidelines for its dosage are poorly defined. There is increasing evidence to suggest that a strategy based on plasma drug monitoring may be useful to detect non-compliance. Therefore, we have developed a population-based pharmacokinetic (POP-PK) model that characterises adaptive changes in methadone kinetics. METHODS: Sparse plasma rac-methadone concentrations measured in 35 opiate-users were assessed using the P-Pharm software. The final structural model comprised a biexponential function with first-order input and allowance for time-dependent change in both clearance (CL) and initial volume of distribution (V ). Values of these parameters were allowed to increase or decrease exponentially to an asymptotic value. RESULTS: Increase in individual values of CL and increase or decrease in individual values of V with time was observed in applying the model to the experimental data. CONCLUSIONS: A time-dependent increase in the clearance of methadone is consistent with auto-induction of CYP3A4, the enzyme responsible for much of the metabolism of the drug. The changes in V with time might reflect both up- and down-regulation of alpha1-acid glycoprotein, the major plasma binding site for methadone. By accounting for adaptive kinetic changes, the POP-PK model provides an improved basis for forecasting plasma methadone concentrations to predict and adjust dosage of the drug and to monitor compliance in opiate-users on maintenance treatment.

Adolescent↗
PubMed1999

A randomized, double-blind, placebo-controlled trial of botulinum A toxin for severe axillary hyperhidrosis.

Excessive axillary hyperhidrosis is a socially embarrassing condition which severely reduces quality of life and may result in psychological disturbance. Available treatment strategies do not resolve the problem in all cases. Intracutaneous injections of botulinum A toxin have been shown to be effective in patients with local sweating disorders. We performed a randomized, double-blind, within-group comparison in 13 individuals (nine women and four men) with severe axillary hyperhidrosis resistant to conventional treatment, to study the effect of intracutaneous injections of botulinum toxin on sweating. A total dose of 200 mouse units of botulinum A toxin (Dysport(R)) was injected into six different sites in one axilla, whereas the other was injected with sterile saline. Objective quantification of sweat production was performed using digitized ninhydrin-stained sheets. Three weeks after treatment, the mean difference in ninhydrin staining between botulinum-treated and placebo-treated axillae was -34.5% (P < 0.001), after 8 weeks -36.9% (P < 0.001) and after 13 weeks -28.4% (P < 0.001). Subjective rating of sweat production was evaluated on a visual analogue scale (0, no sweating, to 100, most severe sweating). Three weeks after treatment the difference between the botulinum-treated and placebo-treated axillae was -56.5% (P < 0.001), after 8 weeks -67.4% (P < 0.001) and after 13 weeks -62.5% (P < 0.001). No serious side-effects were observed.

Adult↗
PubMed1999

Influence of increased c-Myc expression on the growth characteristics of human melanoma.

Overexpression of the proto-oncogene c-myc has been associated with neoplastic transformation in a variety of tumors. For human melanoma high c-myc expression has been found in the vertical growth phase and higher positivity reported in metastases than primary tumors. The principle aim of this study was to determine, whether c-Myc expression influences the metastatic behavior of human melanoma in the absence of lymphocyte-mediated immune phenomena. The growth characteristics and tumor biology of two c-myc transfectants of the human melanoma cell line IGR39D, expressing c-Myc 1.7 and three times over baseline and the respective vector control were analyzed both in vitro and in a severe combined immunodeficient mouse model in vivo. Both c-myc transfectants showed increased growth rates, anchorage independent growth and directed cell movement in culture. Subcutaneously implanted IGR39D melanomas highly overexpressing c-Myc spontaneously formed macroscopic metastases (lymph nodes and lung) in severe combined immunodeficient mice in all cases (n = 7 per group), whereas less prominent c-Myc overexpression caused the development of only lung micrometastases. During the time period leading to terminal disease in animals injected with c-myc transfected human melanoma cells, melanoma development was not seen in vector controls. These findings suggest that constitutive high c-Myc expression in human melanoma results in a more aggressive growth behavior both in vitro and in vivo and favors metastasis in severe combined immunodeficient mice by factors unrelated to immune phenomena such as class I human leukocyte antigen downregulation known to be associated with c-Myc expression.

Animals↗
PubMed1999

Immune complexes from vasculitis patients bind to endothelial Fc receptors independent of the allelic polymorphism of FcgammaRIIa.

UNLABELLED: Cutaneous leukocytoclastic vasculitis is characterized by the deposition of circulating immune complexes, neutrophil extravasation, and vessel destruction, but mechanisms of circulating immune complexes capture within postcapillary venules are unknown. We demonstrate that circulating immune complexes from sera of vasculitis patients bind to cultured endothelium in an Fc gamma receptor IIa-dependent fashion. In lesional skin, endothelial cells bind immunoglobulin G2 > immunoglobulin G3 and immunoglobulin G4, but not immunoglobulin G1, even before obvious neutrophil transmigration and vessel damage. As the human Fc gamma receptor IIa proteins exist in two allotypes (one with a histidine at position 131, which binds immunoglobulin G1, 2, 3 and the other with an arginine at position 131, which binds immunoglobulin G1, and 3, but is unable to bind immunoglobulin G2), we expected an altered prevalence of histidine 131 forms in vasculitis patients. Sequence analysis, however, revealed an equal distribution of allotypes in patients and controls. In conclusion, circulating immune complex binding to endothelial Fc gamma receptor IIa is among the initial steps in the development of vasculitis. Although immunoglobulin G2 is the predominant subtype precipitated at endothelial surfaces, it is not required for fixing circulating immune complexes to endothelium, because patients homozygote for Fc gamma receptor IIa-arginine 131 equally develop leukocytoclastic vasculitis as those bearing the Fc gamma receptor IIa-histidine 131 allele. As immunoglobulin G1 is virtually absent in leukocytoclastic vasculitis lesions and immunoglobulin G4 does not bind to both Fc gamma receptor IIa alleles, these complexes, in addition to immunoglobulin G2, should contain immunoglobulin G3 in order to fix to vascular Fc gamma receptor IIa, at least in persons homozygous for Fc gamma receptor IIa-arginine 131. KEYWORDS: CD32/immunoglobulin G subtypes/leukocytoclastic vasculitis/microvessels.

Alleles↗
PubMed1999

Peripheral lymph node addressins are expressed on skin endothelial cells.

The term "peripheral node addressins" describes a set of several endothelial adhesion molecules, which collectively bind to L-selectin and react with monoclonal antibody MECA-79. They regulate lymphocyte recirculation through peripheral nodes. Their expression is thought to be restricted to a specialized vascular segment within the node, called the high endothelial venule. In certain chronic skin diseases, however, postcapillary venules of the skin may also acquire a high endothelial venule-like morphology. Employing immunohistochemistry on cryostat sections, we found these skin endothelial cells - like peripheral node high endothelial venules - to be reactive with monoclonal antibody MECA-79. Tissue lysates from the same specimens were then analyzed by immunoprecipitation using recombinant human L-selectin Fc-chimeras followed by immunoblotting using monoclonal antibody MECA-79. In contrast to peripheral node endothelium, which mainly expressed peripheral node addressin moieties of molecular sizes 90-110 kDa and 160 kDa, endothelial cells in cutaneous T cell lymphoma skin lesions expressed an additional and not yet defined 220 kDa peripheral node addressin-like molecule. Most surprisingly, even in normal skin specimens, we found a distinct subset of endothelial cells located around hair follicles constitutively expressing 90-110 kDa peripheral node addressin-like moieties. It is intriguing to speculate that - in analogy to the role of peripheral node addressins in peripheral nodes - the induced expression of peripheral node addressins in chronic T cell mediated skin diseases is responsible for a sustained lymphocyte recruitment. The constitutive expression of peripheral node addressins on perifollicular endothelium may serve for a continuous lymphocyte recirculation through normal skin.

Antigens, Surface↗
PubMed1999

Analysis of illicit ecstasy tablets: implications for clinical management in the accident and emergency department.

OBJECTIVE: To examine the composition of illicitly manufactured "ecstasy" tablets sold on the UK drugs market. METHODS: Analysis by gas chromatography of 25 illicit ecstasy tablets handed in under amnesty to Leeds Addiction Unit. RESULTS: Illicitly manufactured ecstasy tablets contain a range of ingredients, of widely differing concentrations, and even tablets with the same brand name have variable concentrations of active ingredients. Concentrations of 3,4-methylenedioxymethamphetamine (MDMA) more popularly known as ecstasy, varied 70-fold between tablets. Nine tablets contained neither MDMA nor related analogues. CONCLUSIONS: These results have implications for emergency workers attending to those who have become casualties of the drug ecstasy. Those claiming to have ingested ecstasy may actually have taken other agents that require different clinical management.

Chromatography, Gas↗
PubMed1999

Therapeutic drug monitoring for methadone: scanning the horizon.

The initial assessment and subsequent monitoring of compliance in methadone treatment programmes are excessively reliant on the accuracy of self-report from opiate addicts themselves. Given the central position of methadone treatment in the therapeutic options currently available and with the increasing number of opiate addicts requiring treatment, improved methods of judging optimal methadone treatment are required. This paper explores the possible future options for assessing the adequacy of methadone prescribing from the analysis of methadone levels in urine, blood, hair and saliva. The particular promise of plasma therapeutic drug monitoring for methadone is explored, accompanied by an account of the state of the art at the time of writing.

Heroin↗
PubMed1999

Vascular-endothelial cadherin (CD144)- but not PECAM-1 (CD31)-based cell-to-cell contacts convey the maintenance of a quiescent endothelial monolayer.

BACKGROUND: In vivo, all blood vessels are lined by a single layer of flattened noncycling endothelial cells. We tested the hypothesis that the maintenance of such a quiescent endothelial monolayer depends on homotypic contacts between not yet defined growth-inhibitory molecules located at interendothelial junctions. METHODS: ECV304 cells, which lack endogenous vascular endothelial cadherin (VE cadherin) or CD31 expression, were transfected with cDNA encoding for the respective proteins or with the empty vector. RESULTS: In VE cadherin transfectants, beta-catenin was targeted to junctional regions and the F-actin-based cytoskeleton formed parallel bundles reaching from one cell border to the other. In contrast, in CD31 transfectants and in empty vector cells, beta-catenin was dispersed throughout the cytoplasm, and F-actin formed short, plump and criss-cross bundles. On a two-dimensional plastic matrix, both, VE cadherin and CD31 transfectants formed clusters of polygonal cells, whereas in three-dimensional gels, only VE cadherin cells were able to form tubes. Empty vector cells grew in a fibroblast-like pattern and neither formed clusters nor tubes. Most importantly, whereas CD31 and empty vector cells grew on top of each other, formed polylayers and maintained cycling even after reaching confluence, VE cadherin cells strictly maintained a single layer of flattened cells and the numbers of cycling cells dramatically dropped after reaching a continuous monolayer. CONCLUSION: The insertion of VE cadherin into ECV304 cells produces a cell type which mimics endothelial growth characteristics seen in vivo.

Antigens, CD↗
PubMed1999

Hybridization among sympatric species of Rhododendron (Ericaceae) in Turkey: morphological and molecular evidence.

Rhododendron (Ericaceae) is a large genus in which barriers to hybridization are especially weak, but many species are maintained in sympatry. Hybridization among four species of Rhododendron subsect. Pontica, which occur in sympatry in Turkey, was investigated. Material of R. ponticum, R. smirnovii, R. ungernii, and R. caucasicum and their putative hybrids was collected from the wild. Based on morphology, chloroplast DNA and nuclear ribosomal DNA restriction fragment length polymorphism (RFLP) profiles, each accession was identified as a species or hybrid combination. Five of the six possible hybrid combinations among the four species were detected. Rhododendron ponticum × R. smirnovii was represented by a single individual and R. caucasicum × R. smirnovii by one small group of hybrid plants. The combinations R. ponticum × R. ungernii and R. ungernii × R. smirnovii showed evidence of frequent backcrossing, while R. ponticum × R. caucasicum appeared unusual in that an intermediate hybrid type was abundant, whereas hybrids with phenotypes approaching either parent were rare. Possible explanations of this latter situation are discussed. The results suggest that natural hybridization among Rhododendron species is common and that ecological factors are important in maintaining integrity when species occur in sympatry.

Journal Article↗
PubMed1998

[Successively improved prognosis in erythrocyte immunization].

Prognosis in cases of erythrocyte immunisation has improved continuously over the past decades. Morbidity and mortality have been reduced by improvements in management, including screening programmes, non-invasive ultrasound evaluation and invasive procedures. The article provides an outline of the latest developments in the management of erythrocyte immunisation, and several controversial issues are discussed, such as antibody screening, strategies for the reduction of antibody titres, and the organisation of care.

Anemia, Neonatal↗
PubMed1998

Treatment of metastatic malignant melanoma with dacarbazine plus fotemustine.

Despite the poor prognosis of metastatic malignant melanoma, polychemotherapy with dacarbazine and fotemustine has shown promising results in several studies. We report on the clinical efficacy of a new sequential administration regimen with dacarbazine at a dose of 200 mg/m2 followed 24 h later by fotemustine 100 mg/m2 every 4 weeks in 63 patients with metastatic melanoma. A complete response was noted in 3 patients (5%), a partial response in 4 patients (6%), stable disease in 33 patients (5%) and progressive disease in 23 patients (37%). The duration of the 3 complete responses was 5, 14+ and 60+ months, for the 4 partial responses, 3, 4, 6 and 13 months. The median duration for stable disease was 4 months. The best response rates were obtained for lung and lymph node metastases. Toxicity was mild and mainly limited to haematological without pulmonary side-effects. Although there was a relatively low objective response rate, this chemotherapy regimen as a palliative treatment, is potentially valuable for patients with progressive stage IV melanoma.

Adult↗
PubMed1998

bcl-2 antisense therapy chemosensitizes human melanoma in SCID mice.

Malignant melanoma is a prime example of cancers that respond poorly to various treatment modalities including chemotherapy. A number of chemotherapeutic agents have been shown recently to act by inducing apoptosis, a type of cell death antagonized by the bcl-2 gene. Human melanoma expresses Bcl-2 in up to 90% of all cases. In the present study we demonstrate that bcl-2 antisense oligonucleotide treatment improves the chemosensitivity of human melanoma grown in severe combined immunodeficient (SCID) mice. Our findings suggest that reduction of Bcl-2 in melanoma, and possibly also in a variety of other tumors, may be a novel and rational approach to improve chemosensitivity and treatment outcome.

Actins↗
PubMed1998

Granulocyte/macrophage colony-stimulating factor increases wound-fluid interleukin 8 in normal subjects but does not accelerate wound healing.

Granulocyte/macrophage colony-stimulating factor (GM-CSF) is thought to play an important part under conditions of impaired wound healing. This is not confirmed and it is also unknown whether GM-CSF affects wound healing in healthy subjects. We conducted a randomized, double-blind, placebo-controlled pilot study in 10 healthy volunteers. Triplicate wounds (10 x 10 x 0.5 mm) on the right and left upper thigh were made by a razor blade and injected with GM-CSF or a solvent control. Four of the 10 volunteers were re-examined after 2 months by investigating the healing of a new set of triplicate wounds injected with solvent control alone (controls). Factors measured were wound healing time, wound-fluid cytokines by enzyme-linked immunosorbent assay, wound-fluid inflammatory cells and dermal thickness by ultrasonography. Intradermal injection with 20 micrograms GM-CSF per wound caused significantly higher wound-fluid GM-CSF and interleukin 8 (IL-8) levels than in controls, but did not affect the time needed for wound closure (mean 11 days in all groups), dermal thickness, wound-fluid inflammatory cells or other wound-fluid cytokines, e.g. vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF). Transforming growth factor (TGF) beta 1 and beta 2, epidermal growth factor (EGF), and beta-fibroblast growth factor (beta-FGF) were not measurable in any wound fluid. The lack of efficacy of exogenously delivered GM-CSF on wound healing in healthy subjects is probably based on the failure of GM-CSF to induce 'wound-healing cytokines' like PDGF, FGF, TGF, EGF or VEGF. However, GM-CSF increases IL-8 release, which is a potent chemotactic cytokine, indicating that GM-CSF might be of therapeutic value under conditions of impaired chemotaxis.

Adult↗
PubMed1998

Erythema multiforme associated human autoantibodies against desmoplakin I and II: biochemical characterization and passive transfer studies into newborn mice.

The demonstration of circulating autoantibodies directed against the constitutive desmosomal plaque proteins desmoplakin (dp) I and II in mucocutaneous lesions in a subset of patients with erythema multiforme major, suggests that humoral immune mechanisms may play a role in the pathogenesis of this severe skin disease. In this study we identified a specific peptide sequence--YSYSYS--representing an antigenic binding site for the human autoantibodies. This epitope is localized at the extreme carboxy terminal domain of dp thought to be responsible for the assembly of keratin filaments with desmosomes. To test the possibility whether these antibodies may exert any pathologic effects in vivo, human autoantibodies were affinity purified on a corresponding synthetic peptide matrix and peptide-specific antibodies were raised in rabbits. After repeated subcutaneous injections into newborn mice, affinity-purified human autoantibodies and anti-peptide rabbit IgG were detected on desmosomal plaques of keratinocytes overlying the injection site. Histologic and electron microscopic examinations showed hydropic degeneration of basal and suprabasal keratinocytes, dyskeratosis, signs of suprabasal acantholysis, and keratin filaments detached from the desmosomal plaques clumping around the nucleus. We demonstrate that autoantibodies are directed to an epitope within a dp domain crucial for the interaction of keratin filaments with desmosomes, and, when injected subcutaneously into newborn mice, produce pathologic changes. These findings imply that autoantibodies to dp could impair the function of desmosome-keratin filament complexes suggesting a pathogenic role in vivo.

Animals↗
PubMed1998

MCP-1 and MIP-1alpha are most efficient in recruiting T cells into the skin in vivo.

To analyze T cell recruitment by chemokines in vivo, we used SCID mice grafted with human skin onto their backs and human T cells into their peritoneal cavities. rh MIP-1alpha and rh MCP-1, as well as mouse MCP-1, attracted significant amounts of human T cells into human skin grafts, whereas effects of rh RANTES, rh SDF-1, or rh IP-10 were minimal. Human T cells were found in a striking perivascular position exclusively at sites of human endothelium. None of the chemokines recruited human T cells across mouse endothelial barriers. For control purposes, chemokines were injected into the abdominal wall directly above the peritoneal cavity, where human T cells had been injected and were not subjected to flow. At this site all tested chemokines attracted human T cells to an equal extent. In summary, our experiments point towards an important role for MCP-1 and MIP-1alpha as T cell chemoattractants for skin inflammatory conditions.

Animals↗