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T Krieg

Publications and source records attributed to T Krieg.

At least 19 recordsLinked to original sources
PubMed2006

Establishment of stable human fibroblast cell lines constitutively expressing active Rho-GTPases.

Small GTP-binding proteins of the Rho family (RhoA, Cdc42, Rac1) regulate the organisation and the turnover of the cell's cytoskeleton and adhesion structures. A significant function of these cellular structures is to translate and counterbalance forces applied to, or generated by, cells in order to maintain homeostasis and control cell movement. We therefore hypothesised that Rho-GTPases are directly involved in cellular gravity perception and may participate in the alterations induced in microgravity. To define an adequate cellular model allowing to investigate this issue, we have established stable cell lines constitutively expressing active forms of either RhoA, Cdc42, or Rac1. The three cell lines differ by morphology and by their ability to form filopodia, lamellipodia, and bundles of actin stress fibers. Overexpression of the active form of either RhoA, Cdc42, or Rac1 is compatible with cell viability and does not affect cell population doubling time. Thus, our series of mutant cells appear well suited to gain further knowledge on the molecular mechanisms of cellular gravity perception.

Actin Cytoskeleton↗
PubMed2006

Effects of constitutively active GTPases on fibroblast behavior.

The GTP-binding proteins RhoA, Cdc42 and Rac1 regulate the organization and turnover of the cytoskeleton and cell-matrix adhesions, structures bridging cells to their support, and translating forces, external or generated within the cell. To investigate the specific requirements of Rho GTPases for biomechanical activities of clonal cell populations, we compared side-by-side stable lines of human fibroblasts expressing constitutively active (CA) RhoA, Cdc42 or Rac1. There was no marked effect of any CA GTPase on cell adhesion to different extracellular matrix proteins. Cell spreading was CA Rho GTPase specific and independent of the extracellular matrix proteins allowing adhesion. Mechanical properties were dramatically restricted by CA RhoA on bi- and in tri-dimensional surroundings, were boosted by CA Rac1 on bi-dimensional surroundings only, and were not or marginally affected by CA Cdc42. In conclusion, the action of Rho GTPases appears to depend on the task cells are performing.

Actins↗
PubMed2006

[Systemic sclerosis - diagnosis and classification].

Systemic sclerosis (SSc) is a polymorphic and heterogenic systemic disorder with inflammation, fibrosis and vascular damage. Early diagnosis and classification may be difficult if disease expression is oligosymptomatic (undifferentiated), presenting with only Raynaud's phenomenon or limited scleroderma. Scleroderma specific antinuclear autoantibodies, which are present early and persistently in about 90% of the patients with SSc, play an important taxonomic role. Scleroderma specific findings in nailfold capillary microscopy are sensitive and predictive for evolving SSc. An algorithm will be presented for the diagnosis and classification of SSc using clinical, capillaroscopic and serologic criteria, which are also useful for mixed or special forms of SSc. The 6th Outcome Measures in Rheumatology Clinical Trials (OMERACT) conference proposed different outcome measurements for clinical studies, however, for daily clinical practice there is as yet no consensus on status indices for disease activity, disease related damage or suitable prognostic criteria.

Algorithms↗
PubMed2006

[Current pathophysiological aspects of systemic sclerosis].

Systemic scleroderma is characterized by a chronic inflammatory process of unknown etiology resulting in an increased deposition of connective tissue proteins in the involved organs. Involvement of the vascular system and the resulting fibrosis lead to atrophy and malfunction of the involved internal organs and the skin. Due to the development of new therapeutic concepts in particular with regard to the vascular involvement, the interaction between the vascular system and the connective tissue moves increasingly into focus. This review describes the major advancemades during recent years for the understanding of the pathophysiology of systemic scleroderma.

Animals↗
PubMed2006

Effects of antibodies obtained from patients with dilated cardiomyopathy on the function of isolated rat hearts.

BACKGROUND: Cardiac autoantibodies may play a pathophysiological role in cardiac dysfunction of patients suffering from dilated cardiomyopathy (DCM). Immunoadsorption (IA), which removes antibodies from patients' plasma, may consequently improve cardiac function in DCM. The functional effects of DCM antibodies are only partly understood. MATERIALS AND METHODS: DCM patients (n = 10) were treated with IA by application of antibody columns directed against human immunoglobulin (Ig). IA was also performed with plasma taken from 10 healthy donors (controls). The antibodies eliminated and purified by IA were collected and dialysed. Rat hearts were isolated and perfused retrogradely via the aorta in Langendorff mode. During constant-pressure and constant-volume perfusion of the hearts, the influence of diluted antibodies on contractility, relaxation, and on coronary perfusion was analysed. RESULTS: Antibodies obtained from controls had no effect on contractility and relaxation of isolated perfused hearts during constant-pressure and constant-volume perfusion. In contrast, during constant-pressure perfusion, collected DCM antibodies caused immediate and dose-related reduction of contractility (dLVP/dtmax: dilution -1:32 = -7.1 +/- 1.1%; dilution -1:2 = -20.1 +/- 2.1%; P < 0.001) and diastolic relaxation (dLVP/dtmin: dilution -1:32 = -11.1 +/- 1.5%; dilution -1:2 = -23.9 +/- 2.2%; P < 0.001). The heart rate did not change significantly in either group. The effects of DCM antibodies on contractility and relaxation remained detectable during constant-volume perfusion. The observed reduction of contractility and diastolic relaxation was accompanied by impairment of coronary perfusion. CONCLUSION: In the rat heart, antibodies obtained from DCM patients may impair contractility and relaxation, and thereby probably also coronary perfusion.

Animals↗
PubMed2005

Interleukin 4 and prolonged hypoxia induce a higher gene expression of lysyl hydroxylase 2 and an altered cross-link pattern: important pathogenetic steps in early and late stage of systemic scleroderma?

The major pathological processes of systemic scleroderma (SSc) comprise inflammation and microvascular damage in the early or acute progressive stage as well as tissue fibrosis and hypoxia in the chronic end stage. Fibrosis seems to be a general phenomenon characterized by an increase of hydroxylysine aldehyde derived collagen cross-links which has been shown in vitro for systemic scleroderma fibroblasts. In the present study, we analyzed the cross-link pattern and the gene expression of lysyl hydroxylase 2 (LH2) in the skin of SSc. Furthermore, we determined the modulatory impact of inflammatory cytokines (interleukin 4, TNF- alphaand interleukin 1alpha/beta) and prolonged hypoxia on the cross-link profile and the gene expression of LH2, respectively. The concentration of hydroxylysine aldehyde derived cross-links was significantly increased in SSc, while the level of lysine aldehyde derived cross-links was not changed. Accordingly, a marked increase of the transcriptional level of LH2 was found. In long term dermal fibroblast cultures, only interleukin 4 induced an increase of hydroxylysine aldehyde derived cross-links accompanied by a higher gene expression of LH2. Furthermore, prolonged hypoxia induced a marked increase of the mRNA level of LH2 in relation to collagen I. The skin of SSc is characterized by an increase of the transcriptional activity of LH2 leading to an altered cross-link pattern. The changes in the quality of the collagenous matrix can also be obtained in cell culture by the exposure of fibroblasts to interleukin 4 or prolonged hypoxia emphasizing the role of this mediator in the acute and the low oxygen tension in the chronic phase of the disease.

Cell Hypoxia↗
PubMed2005

[PM-Scl antibody positive systemic sclerosis associated with inclusion-body myositis].

We describe a 72- year-old patient with a ten year history of anti-PM-Scl positive systemic sclerosis associated with inclusion-body myositis. While the association of dermatomyositis and polymyositis with anti-PM-Scl positive systemic sclerosis is frequently reported, inclusion-body myositis was, to the best of our knowledge, only previously described once in association with anti-PM-Scl-positive systemic sclerosis. The distinction between inclusion-body myositis and other forms of inflammatory myopathy, like the histopathologically well distinguishable polymyositis or dermatomyositis, is relevant because of the poor response of inclusion- body myositis to immunosuppressive treatment. Our case underlines that in patients with anti-PM-Scl-positive systemic sclerosis and treatment resistant progressive myopathy the diagnosis of inclusion body myositis should be considered.

Aged↗
PubMed2005

Anti-CD20 monoclonal antibody (rituximab) in the treatment of pemphigus.

BACKGROUND: Pemphigus is a severe autoimmune blistering disorder caused by autoantibodies to desmoglein 1 and 3. The disease course is typically severe, thus requiring multiple immunosuppressive agents. The treatment is still challenging and in some patients with recalcitrant disease, therapies fail and therapeutic options are limited. OBJECTIVES: To investigate whether depletion of B lymphocytes that are thought to produce disease-causing autoantibodies shows a long-term benefit in pemphigus. METHODS: Five patients diagnosed as having pemphigus vulgaris and pemphigus foliaceus were treated with the monoclonal antibody rituximab. Rituximab was administered intravenously at a dosage of 375 mg m(-2) once weekly for 4 weeks. RESULTS: The treatment was well tolerated and all patients showed a good response over a follow-up period of up to 3 years, allowing immunosuppressive treatment to be reduced or terminated. B-cell depletion persisted for 6-12 months, and in one patient for almost 3 years. CONCLUSIONS: This study highlights the prolonged effect and disease control after one single course of rituximab and further extends the spectrum of treatments of bullous autoimmune disorders.

Adult↗
PubMed2004

Augmented taurine release is not the mechanism of ischemic preconditioning's cardioprotection.

In ischemic preconditioning (IPC) a brief ischemic period protects the heart from a subsequent ischemic insult by an unknown mechanism. Osmotic swelling has been proposed to be a major cause of cell death when ischemic tissue is reperfused. The present study tests whether the preconditioned heart during reperfusion might release more taurine, an important osmolyte in the cardiac myocytes, to decrease cellular osmolarity, oppose swelling, and preserve viability. We collected the coronary effluent from isolated rabbit hearts for 10 min before and 10 min after preconditioning with 5 min of global ischemia. The heart then experienced 15 min of global ischemia and effluent was collected during reperfusion for 40 min. A control group was studied similarly but without the preconditioning ischemia. Fifteen min of ischemia was chosen to avoid any taurine release caused by ischemic cell death. Taurine was measured with HPLC. In the IPC group there was a postischemic release over baseline of 5.09 +/- 1.51 micromol (approx 3.3% of the total taurine pool), whereas in the control group the release was not significantly different, 5.72 +/- 1.67 micromol. The percent of the taurine pool lost from each heart during reperfusion was calculated based on an assumption of a total content of 20 microM taurine/gm wet weight. Since the amount of taurine released by the isolated rabbit heart following ischemia was not different in preconditioned and non-preconditioned hearts, we conclude that reduced swelling through taurine release is not the mechanism of the cardioprotective effects of IPC.

Animals↗
PubMed2004

Association of killer cell immunoglobulin-like receptors with scleroderma.

OBJECTIVE: Scleroderma is an autoimmune disorder of unknown etiology. A genetic contribution has been demonstrated, and genes influencing activation of the immune system have been potentially identified as candidate genes in this process. The repertoire of killer cell immunoglobulin-like receptors (KIRs) that are involved in the activation of T cells and natural killer cells is highly variable. Recently, an association of KIR2DS2 with vasculitis in patients with rheumatoid arthritis has been reported. Because scleroderma is characterized by an involvement of the vascular system, we sought to determine whether KIR2DS2 is associated with scleroderma. METHODS: We typed 9 KIR genes in 102 patients with scleroderma and in 100 blood donors, using polymerase chain reaction on genomic DNA. RESULTS: Twelve patients with scleroderma, compared with only 2 blood donors, had KIR phenotypes characterized by the presence of the activating KIR2DS2 and the absence of the corresponding inactivating KIR2DL2 (P = 0.005). CONCLUSION: The genetic combination of KIR2DS2+ and KIR2DL2- is associated with scleroderma.

Genetic Predisposition to Disease↗
PubMed2004

Evidence for an S-phase checkpoint regulating DNA replication after heat shock: a review.

Exposure of cells to heat inhibits a number of nuclear activities associated with semi-conservative replication of DNA including the incorporation of radiolabelled precursors into acid-insoluble DNA, the initiation of new replicons, the elongation of the DNA fibre at the replication fork, the synthesis and deposition of new histones into chromatin and the reorganization of nascent DNA into mature chromatin. These effects are likely to underlie the heat sensitivity of S-phase cells and may contribute to the radiosensitization observed in this phase of the cell cycle. While some of these effects may be explained as 'passive' consequences of heat-induced damage on chromatin structures experiments reviewed here point to the activation of a checkpoint as a contributing factor to the observed inhibition of DNA replication. Activation of a heat responsive S-phase checkpoint targets the activity of RPA via interaction with nucleolin. Nucleolin, a major nucleolar protein, is found normally sequestered in the nucleolus. Exposure of cells to heat causes a rapid translocation of nucleolin from the nucleolus into the nucleoplasm that enables RPA/nucleolin interaction. This interaction inhibits functions of RPA associated with the initiation of DNA replication and contributes to the immediate inhibition of DNA synthesis observed after heat shock. The results suggest that the nucleolus serves as a sequestration centre for the temporary inactivation of regulatory molecules, such as nucleolin, capable of regulating essential cellular functions after heat shock. It is speculated that this regulatory process is integrated in the network of responses that determine cell sensitivity to heat and that it may be involved in heat radiosensitization to killing as well.

Animals↗
PubMed2003

TRAIL-beta and TRAIL-gamma: two novel splice variants of the human TNF-related apoptosis-inducing ligand (TRAIL) without apoptotic potential.

Tumour necrosis factor (TNF) related apoptosis-inducing ligand (TRAIL/APO2L) is a recently identified member of the TNF family, which induces programmed cell death in a variety of neoplastic cell types, but not in most nonneoplastic cells. In this study, we report on the identification of two novel alternative splice variants of TRAIL in neoplastic and non-neoplastic human cells lacking either exon 3 (TRAIL-beta) or exons 2 and 3 (TRAIL-gamma). In both splice variants, loss of exon 3 resulted in a frame shift generating a stop codon with consecutive extensive truncation in the extracellular domain. Ectopic expression revealed a loss of proapoptotic potential for both alternative splice variants. In contrast to the predominantly cytoplasmatic localisation of GFP-tagged TRAIL-alpha and TRAIL-beta, TRAIL-gamma showed an additional association with the cell surface and nuclear membrane. In conclusion, alternative splicing might be involved in fine tuning of TRAIL-induced apoptosis and underlines the complexity of the TRAIL system.

Alternative Splicing↗
PubMed2003

Enhanced frequency of a PTPRC (CD45) exon A mutation (77C-->G) in systemic sclerosis.

A point mutation in exon A (C to G transversion at position 77) of human PTPRC (CD45) has recently been associated with the development of multiple sclerosis (MS) for at least a subgroup of patients. In the present report, we studied the frequency of the 77C-->G transversion in two other autoimmune diseases namely systemic sclerosis (SSc) and systemic lupus erythematosus (SLE). The mutation was found with significantly enhanced frequency in patients suffering from SSc suggesting that PTPRC could play a role as susceptibility gene not only in MS but also in other autoimmune diseases. Further understanding of the mode of interaction of mutant PTPRC with other susceptibility genes may uncover mechanisms common in various autoimmune disorders.

Exons↗