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Biomedical subjects

Roland Kaufmann

Publications and source records attributed to Roland Kaufmann.

At least 55 records · Page 3Linked to original sources
PubMed2004

Ligation of the beta4 integrin triggers adhesion behavior of human keratinocytes by an "inside-out" mechanism.

Carcinogenesis is considered as a multistep process involving functional changes in the hemidesmosomal organization. In normal skin keratinocytes, expression of the alpha(6)beta(4) integrin is restricted to the proliferative basal layer and mediates stable adhesion to the underlying basement membrane. Observations in carcinoma cells show a functional and spatial dissociation of the alpha(6)beta(4) integrin from the hemidesmosomal complex, which stimulates cell migration and, therefore, may contribute to carcinoma invasion. We now have evaluated the adhesion behavior of epithelial cells at different stages of transformation in response to activation of the beta(4) integrin. It is demonstrated that ligation of the beta(4) integrin augmented adhesion of carcinoma and pre-carcinoma cells to non-modified plastic. In contrast, adhesion behavior of normal human keratinocytes was not influenced by ligation of the beta(4) integrin. In order to explain the mechanism of beta(4)-mediated adhesion, the hypothesis of an "inside-out" activation of integrins was tested. Evidence is given that for cells expressing the alpha(6)beta(4) integrin, ligation of the beta(4) integrin increased beta(1) integrin-mediated adhesion. Furthermore, ligation of the beta(4) integrin led to phosphorylation of PKB/Akt at both phosphorylation sites. Functional blocking of PKB/Akt by dominant-negative overexpression decreased cell adhesion in response to beta(4) integrin ligation. Taken together, the present data establish a link between the ligation of the beta(4) integrin and beta(1) integrin-mediated cell adhesion in carcinoma and pre-carcinoma cells. Hence, these findings provide further insight into the conversion processes during carcinogenesis and show the beta(4) integrin to be a key regulator of cellular adhesion.

Carcinoma, Squamous Cell↗
PubMed2004

Rationale for clinical trials of coagulation: reactive drugs in hepatocellular carcinoma.

Evidence for the regulation of cancer growth by components of the blood coagulation mechanism provides abundant opportunity for the development of novel hypotheses for the experimental treatment of malignancy. Information available on the heterogeneity in mechanisms of interaction between various cancer cell types, and procoagulant and fibrinolytic pathways, platelets, glycosaminoglycan-regulated growth factors and cell-adhesion molecules indicates that insightful clinical trial design may allow targeting of individual cancer cell types with agents capable of intercepting mechanisms of growth control that are relevant to specific tumor types. This paper reviews the evidence that the common anticoagulant, heparin, inhibits hepatocellular carcinoma cell proliferation and hepatocellular carcinoma tumor dissemination in experimental animals. Clinical trials of heparin performed to date have shown increased tumor response rates and survival in other tumor types. Expression of urokinase-type plasminogen activator by hepatocellular carcinoma cells enhances tumor cell proliferation, motility, invasiveness and metastatic dissemination. Inhibition of the urokinase-type plasminogen activator/plasmin system by protease inhibitors such as aprotinin (Trasylol, Bayer) have shown improvement in the clinical course of certain tumor types. These data suggest that drugs that are well-known in the field of vascular medicine may find a role in the treatment of hepatocellular carcinoma, a common tumor type that has resisted containment by other means.

Animals↗
PubMed2004

PAR1-type thrombin receptor stimulates migration and matrix adhesion of human colon carcinoma cells by a PKCepsilon-dependent mechanism.

The proteinase-activated receptor1 (PAR1) was characterized as a functional receptor for thrombin in cells from different tumor entities. In colon carcinoma, its function has to be defined. In this study we demonstrate that the PAR1-selective agonist peptide TFLLRN induced activation of protein kinase C isoenzymes alpha and epsilon in human HT-29 colon carcinoma cells expressing PAR1 endogeneously. On the cellular level, TFLLRN and thrombin prompted HT-29 cell migration and matrix adhesion by a PKCepsilon-dependent mechanism as concluded because of the inhibition of PAR1-mediated effects by the PKC inhibitor bisindolylmaleimide I and the PKCepsilon translocation inhibitory peptide EAVSLKPT but not by the PKC inhibitor Gö 6976. In addition, blockade of PAR1 by RWJ 56110, a selective PAR1 antagonist, fully abolished the effect of thrombin on HT-29 cell migration and adhesion. Therefore, PAR1 seems to be the responsible receptor for thrombin-induced migration and adhesion of human colon carcinoma cells including PKCepsilon as an essential signal transducer.

Blotting, Western↗
PubMed2004

Proteomic profiling in microdissected hepatocellular carcinoma tissue using ProteinChip technology.

At present, the molecular mechanisms of hepatocellular carcinogenesis are not well understood. It is known, however, that cancer development and progression are accompanied by profound changes at the cellular and subcellular level, involving RNA/DNA and protein structure and function. Therefore, high-throughput, proteomic techniques targeting these biological molecules may provide novel insights into HCC genesis and prognosis. We characterized tissue protein profiles from 10 HCC patients using ProteinChip technology (SELDI) which is able to detect minute amounts of proteins and moreover to analyze complex protein pattern. Therefore, after histopathological examination, proteins from kryostat sections of non-tumorous hepatic tissue as well as from central and peripheral tumor areas were isolated from complete histological sections or from selected and microdissected tissue areas. Analysis on the SAX and WCX ProteinChip Arrays revealed 14-26, and 25-29 differentially expressed peaks respectively, which characterized non-tumorous and tumor tissue (p< or =0.05). One feature which allows differentiation between central tumor and peripheral tumor regions could only be detected in microdissected tissue. Using ProteinChip technology in combination with tissue microdissection it is possible to investigate complex changes at the protein level in hepatocellular cancer associated with tumor development and progression.

Biomarkers, Tumor↗
PubMed2003

Determination of 8-methoxypsoralen in human plasma, and microdialysates using liquid chromatography-tandem mass spectrometry.

The validation of a LC/MS/MS method for the determination of 8-methoxypsoralen (8-MOP) in human plasma and microdialysates after topical application is described. Plasma samples were extracted by liquid-liquid extraction with diisopropylether using 4,5',8-trimethylpsoralen (TMP) as internal standard. Chromatographic separation of plasma sample extracts was carried out using a short narrow-bore Nucleosil C18 column (30 mm x 2.0 mm i.d.) with acetonitrile/(2 mM ammonium acetate buffer, 2 mM acetic acid) (80:20, v/v). For mass spectrometric analysis an API 3000 triple quadrupole mass spectrometer was employed. The mass transitions used were m/z 217.2-->174.0 for 8-MOP and m/z 229.1-->142.1 for TMP. Microdialysis samples diluted with an equal amount of acetonitrile did not require any extraction and were analyzed directly on a narrow-bore Nucleosil C18 column (70 mm x 2.0mm i.d.) with acetonitrile/(2 mM ammonium acetate buffer, 2 mM acetic acid) (50:50, v/v) with the mass transition m/z 217.2-->174.0. The assays were validated over the concentration ranges of 0.5-50 ng/ml for plasma samples and 0.25-50 ng/ml for microdialysates, respectively.

Chromatography, Liquid↗
PubMed2003

PPARalpha activators inhibit vascular endothelial growth factor receptor-2 expression by repressing Sp1-dependent DNA binding and transactivation.

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors, originally implicated in the regulation of lipid and glucose homeostasis. In addition, natural and synthetic PPAR activators may control inflammatory processes by inhibition of distinct proinflammatory genes. As signaling via the vascular endothelial growth factor receptor-2 (VEGFR2) pathway is critical for angiogenic responses during chronic inflammation, we explored whether known antiinflammatory effects of PPAR ligands are mediated in part through diminished VEGFR2 expression. In this study, PPARalpha agonists are found to inhibit endothelial VEGFR2 expression, whereas predominant PPARgamma ligands remained without discernible effects. Time- and concentration-dependent inhibition is demonstrated both at the level of protein and mRNA VEGFR2 expression. Inhibitory effects of PPARalpha agonists on transcriptional activity of the VEGFR2 promoter are conveyed by an element located between base pairs -60 and -37 that contains two adjacent consensus Sp1 transcription factor binding sites. Constitutive Sp1-containing complex formation to this sequence is decreased by PPARalpha treatment, indicating that VEGFR2 gene expression is inhibited by repressing Sp1 site-dependent DNA binding and transactivation. Our coimmunoprecipitation experiments revealed enhanced protein interactions between PPARalpha and Sp1 on PPARalpha activation, thus constituting a probable mechanism by which PPARalpha activators decrease Sp-dependent binding activity to the VEGFR2 promoter. Hence, molecular mechanisms by which PPARs modulate the rate of gene transcription may include direct interactions between specific transcription factors and PPARs that ultimately result in reduced DNA binding to their respective response elements.

Binding Sites↗
PubMed2003

Metronomic oral low-dose treosulfan chemotherapy combined with cyclooxygenase-2 inhibitor in pretreated advanced melanoma: a pilot study.

PURPOSE: The safety and efficacy of oral metronomic low-dose treosulfan chemotherapy in combination with the cyclooxygenase-2 (COX-2) inhibitor rofecoxib as a compound with antiangiogenic potential, a therapeutic regimen optimally targeting endothelial cells instead of tumor cells, were assessed in pretreated advanced melanoma patients. METHODS: Endothelial cells were analyzed for proliferation, apoptosis and cytotoxicity in response to increasing concentrations of treosulfan, either in the absence or presence of COX-2 inhibitor, to determine whether inhibition of COX-2 enhanced the effect of treosulfan on cell function. In a clinical pilot study, 12 consecutive patients with pretreated advanced melanoma, meeting the eligibility criteria were enrolled. Patients received combined daily treosulfan chemotherapy (500 mg) with rofecoxib (25 mg). Metastatic lesions were assessed every 12 weeks. Patients with responsive or stable disease were eligible for a further 12-week treatment period. Response criteria according to the WHO handbook for reporting results of cancer treatment were applied. Side effects were classified according to the National Cancer Institute's Common Toxicity Criteria v2.0. RESULTS: At noncytotoxic concentrations, treosulfan inhibited endothelial cell proliferation in a dose-dependent fashion. Simultaneous inhibition of COX-2 significantly increased the extent to which treosulfan suppressed cell proliferation, without inducing cytotoxicity. In the pilot study in which 12 patients were treated, toxicity was mild; only hematologic toxicity of grade II was seen. An objective response was noted in one patient, and four patients showed stabilization of their disease for 24 weeks (one) and 36 weeks (three). The patient who had a partial response subsequently showed stable disease for 48 weeks. The median survival time was 13 months. CONCLUSIONS: As increases in response rates following polychemo- or biochemotherapy have not been shown to correlate with prolongation in overall survival, more durable control of metastatic melanoma represents an attractive therapeutic goal. Thus, regimens scheduled to primarily target endothelial cells may potentially provide a palliative alternative that preserves quality of life in the absence of significant treatment-related toxicity.

Adult↗
PubMed2003

[The selective cyclooxygenase-2 inhibitor celecoxib is a safe alternative in patients with pseudo-allergic reactions to nonsteroidal anti-inflammatory drugs].

BACKGROUND: Adverse reactions to nonsteroidal anti-inflammatory drugs (NSAIDs) are frequent, and the need to identify a safe alternative drug is a common problem in clinical practice. We assessed the tolerability of the selective cyclooxygenase-2 inhibitor celecoxib in a group of NSAID-sensitive patients. PATIENTS AND METHODS: 77 patients (24 males, 53 females, age 31-80 years) with a history of adverse reactions to NSAIDs underwent standardized skin prick, scratch and patch tests along with oral, placebo-controlled blinded exposure to celecoxib (maximum single dose 200 mg, cumulative daily dose 350 mg). RESULTS: 21 patients had a history of cutaneous reactions only (urticaria), 25 had encountered respiratory symptoms (asthma), 18 reported cutaneous as well as respiratory symptoms, and in 13 patients an anaphylactoid shock occurred. Acetylsalicylic acid triggered symptoms in 38 patients. In 46 cases, several NSAIDs of different chemical groups caused symptoms. Oral challenge with celecoxib was tolerated by all 77 patients without adverse effects. CONCLUSION: This study demonstrates that celecoxib does not have cross-intolerance to NSAIDs. Celecoxib is a safe alternative in subjects with previous adverse reactions to NSAIDs.

Adult↗
PubMed2003

HPLC analysis of vitamin E isoforms in human epidermis: correlation with minimal erythema dose and free radical scavenging activity.

The content and composition of different vitamin E isoforms was analyzed in normal human skin. Interestingly the epidermis contained 1% alpha-tocotrienol, 3% gamma-tocotrienol, 87% alpha-tocopherol, and 9% gamma-tocopherol. Although the levels of tocotrienol in human epidermis appear to be considerably lower than reported in the hairless mouse, the presence of significant amounts of tocotrienol levels leads to speculation about the physiological function of tocotrienols in skin. Besides antioxidant activity and photoprotection, tocotrienols may have skin barrier and growth-modulating properties. A good correlation was found for epidermal alpha-tocopherol (r = 0.7909, p <.0003), gamma-tocopherol (r = 0.556, p <.025), and the total vitamin E content (r = 0.831, p <.0001) with the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging in epidermis, as assessed by electron paramagnetic resonance (EPR) spectroscopy. In human epidermis, alpha-tocopherol is quantitatively the most important vitamin E isoform present and comprises the bulk of first line free radical defense in the lipid compartment. Epidermal tocotrienol levels were not correlated with DPPH scavenging activity. The minimal erythema dose (MED), an individual measure for sun sensitivity and a crude indicator for skin cancer susceptibility, did not correlate with the epidermal content of the vitamin E isoforms. Hence it is concluded that vitamin E alone is not a determinant of individual photosensitivity in humans.

Chromans↗
PubMed2003

Fluid shear stress-induced transcriptional activation of the vascular endothelial growth factor receptor-2 gene requires Sp1-dependent DNA binding.

Hemodynamic forces play a fundamental role in the regulation of endothelial cell survival. As signaling via the vascular endothelial growth factor (VEGF) receptor-2 pathway has been previously demonstrated to impact endothelial cell survival, we hypothesized that laminar shear stress may facilitate survival in part by inducing VEGF receptor-2 expression. This study shows a time- and dose-dependent upregulation of endothelial VEGF receptor-2 expression by fluid shear stress in microvascular and large-vessel derived endothelial cells. A functional analysis of the 5'-regulatory region of the VEGF receptor-2 promoter localized the shear stress-response element to a sequence between bp -60 and -37 that encompasses two adjacent consensus Sp1 transcription factor binding sites. Constitutive and shear stress-inducible Sp1-dependent complexes are bound to this element, indicating that fluid shear stress-induced transcriptional activation of the VEGF receptor-2 gene requires Sp1-dependent DNA binding. Together, these results suggest that biomechanical stimulation may lead to endothelial cell survival by upregulating VEGF receptor-2 expression.

Binding Sites↗
PubMed2003

Increased Sp1 phosphorylation as a mechanism of hepatocyte growth factor (HGF/SF)-induced vascular endothelial growth factor (VEGF/VPF) transcription.

Hepatocyte growth factor (HGF/SF)-induced expression of vascular endothelial growth factor (VEGF/VPF) has been implicated in paracrine amplification of angiogenesis, contributing to angiogenic responses during inflammation, wound healing, collateral formation and tumor growth. We have shown previously that HGF/SF-mediated VEGF/VPF expression by keratinocytes is primarily dependent on transcriptional activation, and we mapped the HGF/SF-responsive element to a GC-rich region between bp -88 and -65. Sp1-like factors bind to this element constitutively; however the VEGF/VPF promoter is transactivated by HGF/SF in the absence of induced binding activity. In experimental approaches to clarify molecular mechanisms of Sp1-dependent VEGF/VPF gene transcription, neither HGF/SF-dependent changes in nuclear expression nor in relative DNA binding activity of Sp family members to the indicated element were observed. Thus, HGF/SF was hypothesized to induce VEGF/VPF gene transcription via increased transactivation activity of Sp1 owing to biochemical modification. In immunoprecipitation studies, HGF/SF was found to increase the amount of serine-phosphorylated Sp1, revealing a likely mechanism of HGF/SF-induced VEGF/VPF expression, as phosphorylation may enhance the transcriptional activity of Sp1. The contribution of different signaling molecules to HGF/SF-induced VEGF/VPF transcription was demonstrated by the use of chemical inhibition, of expression of kinase-deficient signaling proteins, and by the use of antisense oligonucleotides. Herein, we provide evidence that PI 3-kinase, MEK1/2 and PKC-zeta play a significant role in HGF/SF-induced VEGF/VPF promoter activation. Together, our results elucidate a critical pathway of paracrine amplification of angiogenesis, suggesting that HGF/SF-induced Sp1 phosphorylation may activate VEGF/VPF promoter activity that requires the contribution of distinct signaling molecules.

Animals↗
PubMed2003

[Pseudomelanoma following laser treatment or laser-treated melanoma?].

BACKGROUND: The increasing use of lasers for the removal of pigmented skin lesions has led to a growing risk of erroneously treated malignant melanocytic tumours. PATIENTS AND METHODS: In two patients, both of whom developed a melanoma, the lesions were initially misdiagnosed clinically as a benign naevus and treated with laser vaporisation. RESULTS: On recurrence of the tumours, the diagnosis of melanoma was finally established by histological examination of the excised tumours in which differentiation from pseudomelanoma remained difficult. CONCLUSIONS: In such cases of initially misdiagnosed melanomas, laser removal not only complicates and delays the correct diagnosis but might also worsen the prognosis after recurrence of an incompletely removed tumour.

Adult↗
PubMed2003

Early onset of action and efficacy of a combination of calcipotriene and betamethasone dipropionate in the treatment of psoriasis.

BACKGROUND: Calcipotriene and betamethasone dipropionate are topical treatments for psoriasis vulgaris. Their mode of action is different. Improved risk/benefit may result with concomitant use of the two compounds together. A new vehicle has been created with the objective of obtaining optimal stability of both calcipotriene and betamethasone dipropionate in the combination product. OBJECTIVE: We compared the clinical efficacy of a fixed combination of calcipotriene and betamethasone dipropionate in a new vehicle to calcipotriene in the new vehicle, betamethasone in the new vehicle, and the new vehicle alone. METHODS: This was an international, multicenter, prospective, randomized, double-blind, parallel-group, 4-week study in patients with psoriasis vulgaris amenable to topical treatment. RESULTS: The mean percentage reduction in PASI from baseline to end of treatment was 73.2% in the combination group (n = 301), 48.8% in the calcipotriene group (n = 308), 63.1% in the betamethasone dipropionate group (n = 312) and 28.8% in the new vehicle group (n = 107), (P < .001). The mean percentage reduction in PASI during the first week was 48.1%, 28.4%, 41.4%, and 21.5%, respectively (P < .001). CONCLUSION: A combination product of calcipotriene 50 microg/g and betamethasone dipropionate 0.5 mg/g in the new vehicle shows superior efficacy with a more rapid onset of action than the new vehicle containing either constituent alone in the treatment of psoriasis vulgaris.

Adolescent↗
PubMed2003

Herpes simplex virus type 2-associated eosinophilic cellulitis (Wells' syndrome).

Eosinophilic cellulitis (Wells' syndrome) is a recurrent inflammatory dermatosis characterized by massive infiltration of eosinophils into the skin. Drugs and pathogens have been recognized causes of eosinophilic cellulitis. We report the repeated association of eosinophilic cellulitis with herpes simplex virus type 2 infections. Antiviral therapy led to a complete remission of eosinophilic cellulitis, indicating that causative treatment of underlying diseases can be effective in controlling eosinophilic cellulitis.

Antiviral Agents↗
PubMed2003

Safety and efficacy of nonsteroid pimecrolimus cream 1% in the treatment of atopic dermatitis in infants.

OBJECTIVE: The safety and efficacy of a 1% cream formulation of pimecrolimus, a selective, nonsteroid immunomodulator, was studied in infants with atopic dermatitis (AD). METHODS: During a 6-week double-blind phase, 186 infants with mild/moderate AD were randomly assigned to twice-daily pimecrolimus cream 1% or vehicle. All patients were subsequently treated with open-label pimecrolimus for 20 weeks. RESULTS: At the end of the double-blind phase, 54.5% and 23.8% of patients in the pimecrolimus and vehicle groups, respectively, were clear or almost clear of AD (P <.001). Similar improvements were observed in the Eczema Area and Severity Index, pruritus assessment, and the care giver's assessment. By the first return visit, 69.9% and 36.5% of pimecrolimus and vehicle-treated patients, respectively, achieved absent or mild pruritus. Efficacy during the double-blind phase was maintained throughout the open-label phase. Vehicle-treated patients transferring to open-label pimecrolimus rapidly achieved disease control comparable to those receiving continuous pimecrolimus. There were no significant differences between groups in application site reactions or skin infections. Most adverse events were mild or moderate and unrelated to treatment. CONCLUSIONS: Pimecrolimus was safe in infants with AD, with rapid and sustained efficacy. Pimecrolimus holds promise as a valuable new treatment option for the youngest patients with AD.

Administration, Cutaneous↗
PubMed2003

Efficacy of dexpanthenol in skin protection against irritation: a double-blind, placebo-controlled study.

Dexpanthenol is popular in treating various dermatoses and in skin care, but few controlled clinical trials have been performed. We investigated the efficacy of dexpanthenol in skin protection against irritation in a randomized, prospective, double-blind, placebo-controlled study. 25 healthy volunteers (age 18-45 years) were treated for the inner aspect of both forearms with either Bepanthol Handbalsam containing 5% dexpanthenol or placebo x2 daily for 26 days. From day 15-22, sodium lauryl sulfate (SLS) 2% was applied to these areas x2 daily. Documentation comprised sebumetry, corneometry, pH value and clinical appearance (photographs). 21 volunteers completed the study, 3 were excluded because of non-compliance and 1 experienced a non-study-related, severe, adverse event. Only corneometry yielded a statistically significant difference, with decreased values following SLS challenge at the placebo sites (P < 0.05). Intraindividual comparisons showed superior results at the dexpanthenol-treated sites in 11 cases and in only 1 case at the placebo site. 6 volunteers experienced an irritant contact dermatitis, with more severe symptoms at the placebo site in 5 cases. In conclusion, dexpanthenol exhibits protective effects against skin irritation. The initiation of a study to evaluate the efficacy of dexpanthenol in preventing irritant occupational contact dermatitis under real workplace conditions is validated.

Administration, Topical↗