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W Stremmel

Publications and source records attributed to W Stremmel.

At least 19 recordsLinked to original sources
PubMed2007

Helicobacter pylori-induced apoptosis in T cells is mediated by the mitochondrial pathway independent of death receptors.

BACKGROUND: Chronic infection with Helicobacter pylori is related to the pathogenesis of the noncardia carcinoma of the stomach. In this study we investigated the mechanisms of H. pylori-induced apoptosis in T lymphocytes, which could explain a mechanism of immune evasion facilitating chronic inflammation of the mucosa and gastric carcinogenesis. MATERIALS AND METHODS: The supernatant of H. pylori culture was used to study the mechanism of apoptosis induction in human leukaemia T cell lines Jurkat and CEM and in primary T cells. The cytotoxin associated gene A (CagA) and vacuolating cytotoxin A (Vac A) positive bacterial strain H. pylori 60190 (CagA(+), VacA(+)) and as a control the less toxic H. pylori strain Tx30a (CagA(-), VacA(-)) were used to produce the supernatant. Cell death was determined by DNA fragmentation and protein expression by Western blot. RESULTS: H. pylori 60190-induced apoptosis was neither blocked by inhibition of the death ligands TRAIL (TNF-related apoptosis-inducing ligand), CD95L/FasL and TNF-alpha (tumour necrosis factor-a) in wild type Jurkat cells nor in FADD(def) (Fas-associated death domain protein) and caspase-8(def) subclones of the Jurkat cell line. Yet, the pancaspase inhibitor zVAD-fmk could inhibit up to 90% of H. pylori-induced apoptosis. Stable transfection of Jurkat wild type cells with Bcl-x(L and) Bcl-2 resulted in marked reduction of H. pylori-induced apoptosis, showing that the mitochondrial pathway is the key regulator. This is supported by the finding that surviving primary human lymphocytes upregulate Bcl-2 when exposed to H. pylori supernatant. CONCLUSIONS: H. pylori-induced apoptosis of T cells is mediated by the mitochondrial pathway and could create a local environment that facilitates life-long infection by immune evasion.

Apoptosis↗
PubMed2006

Clinical presentation, diagnosis and long-term outcome of Wilson's disease: a cohort study.

BACKGROUND: Wilson's disease is a rare inborn disease related to copper storage, leading to liver cirrhosis and neuropsychological deterioration. Clinical data on larger cohorts are limited owing to low disease frequency. OBJECTIVE AND METHODS: We performed a retrospective analysis of 163 patients with Wilson's disease, examined at the University of Heidelberg, Heidelberg, Germany, to determine clinical presentation, diagnostic course and long-term outcome. RESULTS: Diagnostic criteria for non-caeruloplasmin-bound serum copper, serum caeruloplasmin, 24-h urinary copper excretion, liver copper content, presence of Kayser-Fleischer rings and histological signs of chronic liver damage were reached in 86.6%, 88.2%, 87.1%, 92.7%, 66.3% and 73% of patients, respectively. By analysis of the coding region of ATP7B (except exons 2, 3 and 21), disease-causing mutations were detected in 57% and 29% of patients with Wilson's disease on both chromosomes and on one chromosome, respectively. No mutations were detected in 15% of patients with Wilson's disease. No significant differences were found in clinical parameters or initial presentation between patients grouped according to their mutations. The patients with neurological symptoms were significantly older at the onset of symptoms than patients with hepatitic symptoms (20.2 v 15.5 years of age, p<0.05), and the neurological symptoms were associated with a significantly longer time from onset to diagnosis than hepatic symptoms (44.4 v 14.4 months, p<0.05). After initiating treatment, 76.1% of the patients had a stable or improved course of the disease. Disease progression under treatment was more likely for neuropsychiatric than for hepatic symptoms. Side effects of treatment occurred in 74.4% of patients. CONCLUSIONS: Patients with Wilson's disease having predominantly neuropsychiatric symptoms manifest symptoms later, have a longer time delay from onset of symptoms until definitive diagnosis and have a poorer outcome than patients with hepatic symptoms.

Adenosine Triphosphatases↗
PubMed2005

TAp73/Delta Np73 influences apoptotic response, chemosensitivity and prognosis in hepatocellular carcinoma.

We investigated the mechanisms by which TAp73 beta and dominant-negative p73 (Delta Np73) regulate apoptosis. TAp73 beta transactivated the CD95 gene via the p53-binding site in the first intron. In addition, TAp73 beta induced expression of proapoptotic Bcl-2 family members and led to apoptosis via the mitochondrial pathway. Endogenous TAp73 was upregulated in response to DNA damage by chemotherapeutic drugs. On the contrary, DeltaNp73 conferred resistance to chemotherapy. Inhibition of CD95 gene transactivation was one mechanism by which DeltaNp73 functionally inactivated the tumor suppressor action of p53 and TAp73 beta. Concomitantly, DeltaNp73 inhibited apoptosis emanating from mitochondria. Thus, DeltaNp73 expression in tumors selects against both the death receptor and the mitochondrial apoptosis activity of TAp73 beta. The importance of these data is evidenced by our finding that upregulation of DeltaNp73 in hepatocellular carcinoma patients correlates with reduced survival. Our data indicate that Delta Np73 is an important gene in hepatocarcinogenesis and a relevant prognostic factor.

Apoptosis↗
PubMed2005

[A young diabetic with small-nodule liver cirrhosis, high transferrin saturation and negative HFE test].

HISTORY: A 28 year young female presented to our hospital for further evaluation with recently diagnosed diabetes mellitus, hyperpigmentation of the skin, hepato- and splenomegaly, thrombocytopenia and an elevated transferrin saturation (96 %), but a negative test for HFE gene mutations such as C282Y and H63D. FINDINGS: Using the mini-laparascopic technique we diagnosed a smallnodular liver cirrhosis with an iron overload. DIAGNOSIS AND TREATMENT: This is the clinical presentation of one subtype of the so called Non-HFE-hemochromatosis, the juvenile hemochromatosis (HFE2). Other causes of primary and secondary iron overload have been ruled out. Different from the HFE-positive hemochromatosis (HFE 1) in which the gene defect is located on chromosome 6, the defect in HFE 2 is located on chromosome 1. The underlying genetic defect has been localized within recently identified HJV gene. Phlebotomy is the treatment of choice, to be performed until the ferritin level is lower than 50 microg/l. CONCLUSIONS: If liver cirrhosis is present in hemochromatosis, the overall risk of developing heptatocellular carcinoma is 20 times higher than in the normal population. Therefore it is suggested to perform an ultrasound examination of the liver and an AFP-test every 6 months, whereas an MRI-scan should be performed once a year, as a basis for further treatment options.

Adult↗
PubMed2005

[Integrated skills laboratory concept for undergraduate training in internal medicine].

BACKGROUND AND OBJECTIVE: An amendment to the German medical curriculum in April 2002 will place basic practical skills at the centre of medical training. We report here on the implementation and evaluation of an obligatory, tutor-guided, and integrated skills laboratory concept in the field of internal medicine. METHODS: To test the effectiveness of a skills laboratory training on OSCE performance a pilot study was carried out. The experimental group, of 77 students, participated in seven sessions of communication training, skills laboratory training, and bedside teaching, each lasting one and a half hours. The control group of 66 students had as many sessions but was only offered bedside-teaching. The evaluation of acceptance of skills' training as well as the related increase in individual competence is on-going (summer term 2004: n = 176 students). RESULTS: The integrated skills laboratory concept was rated at 3.5 (SD = 1.2) on a 5-point scale and was acknowledged as practice-oriented (M = 4.2; SD = 1.0) and relevant for doctors' everyday lives (M = 3.6; SD = 1.1). Increased levels of competence according to individual self-evaluations proved to be highly significant (p<.001), and results of the pilot study showed that the experimental group had a significantly better OSCE performance than the control group (p<.001). CONCLUSION: This pilot study shows that curriculum changes promoting basic clinical skills are effective and lead to an improved practical education of tomorrow's physicians. The integrated skills laboratory concept is well accepted and leads to a relevant increase in competence in the practice of internal medical. The presented skills laboratory concept in internal medicine is proving to be a viable and efficient learning tool.

Adult↗
PubMed2005

Prophylactic and therapeutic vaccination with dendritic cells against hepatitis C virus infection.

Antigen uptake and presentation capacities enable DC to prime and activate T cells. Recently, several studies demonstrated a diminished DC function in hepatitis C virus (HCV) infected patients showing impaired abilities to stimulate allogenic T cells and to produce IFN-gamma in HCV infected patients. Moreover, DC of patients who have resolved HCV infection behave like DC from healthy donors responding to maturation stimuli, decrease antigen uptake, up-regulate expression of appropriate surface marker, and are potent stimulators of allogenic T cells. A number of studies have demonstrated in tumour models and models of infectious diseases strong induction of immune responses after DC vaccination. Because DC are essential for T-cell activation and since viral clearance in HCV infected patients is associated with a vigorous T-cell response, we propose a new type of HCV vaccine based on ex vivo stimulated and matured DC loaded with HCV specific antigens. This vaccine circumvents the impaired DC maturation and the down regulated DC function of HCV infected patients in vivo by giving the necessary maturation stimuli and the HCV antigens in a different setting and location ex vivo. Strong humoral and cellular immune responses were detected after HCV core DC vaccination. Furthermore, DC vaccination shows partial protection in a therapeutic and prophylactic model of HCV infection. In conclusion, mice immunized with HCV core pulsed DC generated a specific antiviral response in a mouse HCV challenge model. Our results indicate that HCV core pulsed DC may serve as a new modality for immunotherapy of HCV especially in chronically infected patients.

Adoptive Transfer↗
PubMed2005

HJV gene mutations in European patients with juvenile hemochromatosis.

A large variety of mutations within the genes encoding hepcidin (HAMP) and hemojuvelin (HJV) have been identified in patients with the severe iron overload disorder juvenile hemochromatosis (JH). The aim of the present study was to evaluate the molecular background of JH in patients from central parts of Europe. Sequence analyses of HAMP and HJV were performed in seven JH patients from six families from Germany, Slovakia, and Croatia. For detection of the G320V mutation in HJV, a rapid polymerase chain reaction-based assay was developed. No mutations were found within the HAMP gene. Six of seven (86%) JH patients carried at least one copy of the G320V mutation within the HJV gene. Four of these patients were homozygous for the G320V mutation. In addition, two novel HJV mutations were identified (C119F and S328fsX337). Taken together, the present study demonstrates that molecular analysis of the HJV gene is a powerful tool for an early and reliable diagnosis of JH. As in affected patients from Greece, the G320V mutation seems to be widely distributed among JH patients from central parts of Europe. Therefore, detection of the G320V mutation could identify the majority of JH cases from these regions non-invasively.

Adolescent↗
PubMed2005

Regulatory CD4+CD25+ cells reverse imbalances in the T cell pool of bone marrow transplanted TGepsilon26 mice leading to the prevention of colitis.

BACKGROUND AND AIMS: Erroneous thymic selection of developing T lymphocytes may be responsible for the expansion of self reactive T cells or may contribute to the absence of regulatory T cells important in controlling peripheral inflammatory processes. Colitis in bone marrow (BM) transplanted Tgepsilon26 mice is induced by abnormally activated T cells developing in an aberrant thymic microenvironment. We investigated the protective role of regulatory CD4+CD25+ T cells in this model. METHODS: BM from (C57BL/6 x CBA/J) F1 mice was transplanted into specific pathogen free Tgepsilon26 mice (BM-->Tgepsilon26). Transplanted mice received no cells (control), sorted CD4+CD25+, or CD4+CD25- cells from mesenteric lymph nodes (MLN) of normal mice. MLN cell subsets were analysed using membrane markers. Cytokine secretion of MLN cells was measured using intracellular cytokine staining and cytokine secretion in anti-CD3 stimulated cell cultures. Colitis was measured by histological scores. RESULTS: CD4+CD25+ cells were reduced in the MLNs of BM-->Tgepsilon26 mice. Transfer of regulatory CD4CD4+CD25+ but not of CD4+CD25- cells reduced the number of MLN CD4+ T cells in BM-->Tgepsilon26 recipients and increased the number of MLN CD8+ cells, thereby normalising the CD4+/CD8+ ratio. CD4+CD25+ but not CD4+CD25- cell transfer into BM-->Tgepsilon26 mice reduced the number of tumour necrosis factor alpha+ CD4+ cells and increased the secretion of transforming growth factor beta by MLN cells. Transfer of 3 x 10(5) CD4+CD25+ cells after BM transplantation into Tgepsilon26 mice prevented colitis whereas CD4+CD25- cells had no protective effect. CONCLUSIONS: These results suggest that defective selection or induction of regulatory T cells in the abnormal thymus is responsible for the development of colitis in BM-->Tgepsilon26 mice. Transfer of CD4+CD25+ cells can control intestinal inflammation in BM-->Tgepsilon26 mice by normalising the number and function of the MLN T cell pool.

Animals↗
PubMed2005

Retarded release phosphatidylcholine benefits patients with chronic active ulcerative colitis.

BACKGROUND AND AIMS: We examined the hypothesis of an anti-inflammatory effect of phosphatidylcholine in ulcerative colitis. METHODS: A phase IIA, double blind, randomised, placebo controlled study was performed in 60 patients with chronic active, non steroid dependent, ulcerative colitis, with a clinical activity index (CAI) of > or = 4. Retarded release phosphatidylcholine rich phospholipids and placebo were administered at a dose of 6 g daily over three months. The primary end point was a change in CAI towards clinical remission (CAI < or = 3) or CAI improvement by > or = 50%. Secondary end points included > or = 50% changes in endoscopic activity index (EAI), histology, and quality of life scores. RESULTS: Induction of clinical remission (CAI < or = 3) as the primary outcome variable was attained by 16 (53%) patients in the phosphatidylcholine treated group compared with three (10%) in the placebo group (p<0.00001). The rate of clinical remission and CAI improvement was 90% in the phosphatidylcholine group and only 10% in the placebo group. A median drop of seven points in the CAI score (70% improvement) was recorded in the phosphatidylcholine group compared with no change in the placebo group. Secondary end point analysis revealed concomitant drops in EAI and histology scores (p = 0.00016 and p = 0.0067 compared with placebo, respectively). Improvement in quality of life was reported by 16 of 29 evaluated patients in the phosphatidylcholine group compared with two of 30 in the placebo group (p = 0.00005). CONCLUSION: Retarded release oral phosphatidylcholine is effective in alleviating inflammatory activity caused by ulcerative colitis.

Administration, Oral↗
PubMed2005

The iron-regulatory peptide hormone hepcidin: expression and cellular localization in the mammalian kidney.

It is generally accepted that iron homeostasis is mainly controlled in the gastrointestinal tract by absorption of dietary iron. However, recent studies have shown that the kidneys are also involved in iron metabolism. Since the iron-regulatory and antimicrobial peptide hormone hepcidin was originally isolated from human urine we have investigated the expression as well as the zonal and cellular localization of hepcidin in the mammalian kidney and developed an ELISA assay to analyze hepcidin concentrations in serum and urine. The expression of hepcidin was shown by RT-PCR and immunoblot experiments; its cellular localization was studied by immunocytochemistry in human, mouse and rat kidney, which revealed similar patterns of immunoreactivity. Hepcidin expression was absent from the proximal tubule and descending and ascending thin limbs. There was strong expression in the thick ascending limb of the cortex and in connecting tubules. Moderate expression was noted in the thick ascending limb and collecting ducts of the medulla and in collecting ducts of the papilla. Importantly, the cells of the macula densa were unstained. At the cellular level, hepcidin was localized to the apical cell pole of the renal epithelial cells. Based on its presence in urine, hepcidin may be released apically into the urine. Enhanced levels of hepcidin were determined in patients with chronic renal insuffciency (156.8 ng/ml, controls 104.2 ng/ml) indicating that the kidneys may metabolize and/or eliminate the circulating peptide. From the expression of hepcidin in the mammalian kidney, we have concluded that the iron-regulatory hormone is an intrinsic renal peptide which is not only eliminated by the kidney but is also synthesized in the kidney tubular system. Localization of hepcidin in the kidney implicates an iron-regulatory role of this peptide hormone in the renal tubular system, possibly in connection with the iron transporter divalent metal transporter-1.

Adult↗
PubMed2004

Enhanced caspase-8 recruitment to and activation at the DISC is critical for sensitisation of human hepatocellular carcinoma cells to TRAIL-induced apoptosis by chemotherapeutic drugs.

Tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) exhibits potent antitumour activity upon systemic administration in mice without showing the deleterious side effects observed with other apoptosis-inducing members of the TNF family such as TNF and CD95L. TRAIL may, thus, have great potential in the treatment of human cancer. However, about 60% of tumour cell lines are not sensitive to TRAIL. To evaluate the mechanisms of tumour resistance to TRAIL, we investigated hepatocellular carcinoma (HCC) cell lines that exhibit differential sensitivity to TRAIL. Pretreatment with chemotherapeutic drugs, for example, 5-fluorouracil (5-FU), rendered the TRAIL-resistant HCC cell lines sensitive to TRAIL-induced apoptosis. Analysis of the TRAIL death-inducing signalling complex (DISC) revealed upregulation of TRAIL-R2. Caspase-8 recruitment to and its activation at the DISC were substantially increased after 5-FU sensitisation, while FADD recruitment remained essentially unchanged. 5-FU pretreatment downregulated cellular FLICE-inhibitory protein (cFLIP) and specific cFLIP downregulation by small interfering RNA was sufficient to sensitise TRAIL-resistant HCC cell lines for TRAIL-induced apoptosis. Thus, a potential mechanism for TRAIL sensitisation by 5-FU is the increased effectiveness of caspase-8 recruitment to and activation at the DISC facilitated by the downregulation of cFLIP and the consequent shift in the ratio of caspase-8 to cFLIP at the DISC.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Interferon alfa2a induction therapy in combination with ribavirin and amantadine for the treatment of naive patients with chronic HCV infection.

Pilot studies have suggested that the addition of amantadine to interferon (IFN) is effective against hepatitis C virus (HCV). Furthermore, IFN induction therapy seems to improve virological response rates. In this open, randomized, multicentre trial we compared safety and efficacy of a triple therapy comprising IFN alpha 2a, ribavirin and amantadine using high induction doses (6 MU IFN alpha daily for the first 6 weeks) against a therapy with standard IFN alpha dosages over the entire treatment period plus amantadine and ribavirin. A total of 158 naive patients with chronic HCV infection were randomized 1:1. Group A (n = 81): induction therapy with 6 MU IFN alpha daily for 6 weeks, followed by 6 MU three times a week (tiw) for 18 weeks and then 3 MU tiw until week 48. Group B (n = 77): standard therapy with 6 MU IFN alpha tiw for 24 weeks, followed by 3 MU until week 48. All patients received oral ribavirin (10 mg/kg/day) and amantadine (200 mg/day). The triple therapy was safe and well tolerated. There were no significant differences between the groups with respect to biochemical response rates. Groups A and B did not differ in virological response rates at the end of treatment (33%vs 35%) or at the end of the 6 month follow up period (37%vs 39%). We could not detect favourable effects on sustained virological response rates using induction therapy, in either genotype 1 or non-1 infected patients. In summary, induction therapy with 6 MU IFN alpha daily did not result in increased overall response rates compared with standard IFN alpha dosages of 6 MU tiw.

Adolescent↗
PubMed2004

Phosphatidylcholine and lysophosphatidylcholine in intestinal mucus of ulcerative colitis patients. A quantitative approach by nanoElectrospray-tandem mass spectrometry.

BACKGROUND: A defective mucus composition represents a key pathogenetic factor for intestinal injury. Phosphatidylcholine (PC) is an essential component contributing to formation of a hydrophobic mucus layer. For evaluation of PC in the pathogenesis of inflammatory bowel disease, the concentration and composition of PC in the rectal mucus of patients with ulcerative colitis was determined. Electrospray ionization (ESI) tandem mass spectrometry (MS/MS) allows quantification of PC species and enables analysis of crude extracts. METHODS: Lipid extracts of material obtained by light scrapings of the intestinal lumen were analysed quantitatively by nanoESI MS/MS with synthetic internal PC and lysophosphatidylcholine (LPC) standards. PC and LPC species from rectoscopically acquired mucus aliquots of patients with ulcerative colitis were compared to Crohn disease and control subjects. RESULTS: Patients with inactive ulcerative colitis showed significantly less PC and LPC (median 346 [IQR: 230-405] pmol total PC/mg dry weight) in rectal mucus compared to Crohn disease (median 126 [IQR: 465-1941] pmol total PC/mg dry weight) and control subjects (median 1285 [IQR: 850-1639] pmol total PC/mg dry weight) (P < 0.05). The molecular species of PC and LPC were not significantly different between the groups. The most abundant species were PC 16:0/18:1; PC 16:0/18:2; PC 18:0/18:1; PC 18:0/18:2; LPC 16:0; and LPC 18:0. CONCLUSION: NanoESI MS/MS is a suitable tool for analysing and quantifying small amounts of PC in human mucus. Patients with ulcerative colitis have significant less PC in their intestinal mucus despite a comparable PC molecular species composition pattern. This suggests that a low amount of protective mucus PC is a characteristic feature in ulcerative colitis and explains an increased susceptibility to luminal contents.

Adult↗
PubMed2004

Role of apoptosis and CD95-receptor/ligand system in aspirin- and Helicobacter pylori-induced cell death.

BACKGROUND: Helicobacter pylori and aspirin both induce gastric epithelial apoptosis. However, the apoptosis-inducing mechanism of aspirin is still unknown. MATERIAL AND METHODS: Apoptosis induction was measured in several gastric epithelial cell lines after incubation with either aspirin or H. pylori supernatant or with a combination of both. CD95 expression was assessed by FACS analysis and CD95L mRNA was measured by reverse transcription polymerase chain reaction. RESULTS: It could be demonstrated that aspirin- and H. pylori supernatant-induced apoptosis involves increased CD95 expression in three different gastric epithelial cell lines. The combined exposure of H. pylori supernatant and aspirin had synergistic effects on both apoptotic cell death and CD95 expression. Blockade of CD95 signalling with an antagonistic antibody was partially prevented from H. pylori- but not from aspirin-induced apoptosis. Furthermore, CD95L expression was detected after treatment with H. pylori only. CONCLUSIONS: These data suggest that although aspirin-mediated CD95 up-regulation is not relevant for its direct apoptotic effect it may sensitize gastric epithelial cells for H. pylori-induced apoptosis. Collectively our data demonstrate the relation of aspirin- and H. pylori-induced apoptosis from a new perspective.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2004

Pro-hepcidin: expression and cell specific localisation in the liver and its regulation in hereditary haemochromatosis, chronic renal insufficiency, and renal anaemia.

BACKGROUND AND AIMS: The hepatic peptide hormone hepcidin, which has recently been isolated from human plasma and urine, is thought to be a central regulator of iron homeostasis. We investigated the presence and cellular localisation of hepcidin in the liver and developed a non-invasive assay to analyse its regulation in patients with hereditary haemochromatosis (HH), chronic renal insufficiency (CRI), and renal anaemia (RA). METHODS: Expression and localisation of hepcidin was shown by reverse transcription-polymerase chain reaction, western blot, immunocytochemistry, and immunofluorescence in human and guinea pig liver. Serum concentrations were determined in various groups of patients using a sensitive enzyme linked immunosorbent assay (ELISA). RESULTS: Western blot analysis with region specific antibodies identified a approximately 10 kDa peptide corresponding to the apparent molecular mass of pro-hepcidin. Localisation studies revealed that pro-hepcidin is expressed at the basolateral membrane domain of hepatocytes and is also present in blood. We developed a stable sensitive ELISA for detection and determination of pro-hepcidin in human serum. Mean pro-hepcidin level in human serum of healthy volunteers was 106.2 ng/ml. Enhanced levels of pro-hepcidin (148.1 ng/ml) were found in patients with CRI but normal haemoglobin values, indicating that the kidneys may metabolise and/or eliminate the circulating hormone. In contrast, concentrations of pro-hepcidin were significantly decreased in patients with HH (70.2 ng/ml) and also in patients with RA (115.0 ng/ml) compared with the CRI group. CONCLUSIONS: From the detection of pro-hepcidin in human serum, we conclude that the prohormone may be involved in the regulation of iron metabolism in HH. Decreased pro-hepcidin levels could play an important role in the pathogenesis of HH.

Adult↗