PubMed Health⌕ Search

Biomedical subjects

B Wiedenmann

Publications and source records attributed to B Wiedenmann.

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

Sustained virological response in hepatitis C virus type 1b infected patients is predicted by the number of mutations within the NS5A-ISDR: a meta-analysis focused on geographical differences.

BACKGROUND AND AIMS: There is growing evidence that the response of hepatitis C virus (HCV) genotype 1b infected patients towards interferon (IFN) therapy is influenced by the number of mutations within the carboxy terminal region of the NS5A gene, the interferon sensitivity determining region (ISDR). PATIENTS AND METHODS: In order to attain better insight into this correlation, a file comprising published data on ISDR strains from 1230 HCV genotype 1b infected patients, mainly from Japan and Europe, was constructed and analysed by logistic regression. Sustained virological response (SVR) was defined as negative HCV RNA six months after treatment. RESULTS: The distribution of wild-, intermediate-, and mutant-type ISDR sequences differed significantly between Japanese (n = 655) (44.1%, 37.6%, and 18.3%) and European patients (n = 525) (24.8%, 63.4%, and 11.8%; p<0.001). There was a significant positive correlation between the number of ISDR mutations and SVR rate, irrespective of geographical region. The likelihood of SVR with each additional mutation within the ISDR was considerably more pronounced in Japanese compared with European patients (odds ratios 1.82 v 1.39; p<0.001). Pretreatment viraemia of <6.6 log copies/ml and ISDR mutant-type infection was associated with an SVR rate of 97.1% in Japanese patients but only 52.5% in European patients. Pretreatment viraemia was a stronger predictor of SVR than ISDR mutation number in Japanese patients whereas in European patients both parameters had similar predictive power. CONCLUSION: These data support the concept that mutant-type ISDR strains may represent a subtype within genotype 1b with a more favourable response towards IFN therapy.

Antiviral Agents↗
PubMed2004

Mechanisms of diarrhea in the interleukin-2-deficient mouse model of colonic inflammation.

Colitis in interleukin-2-deficient (IL-2(-/-)) mice resembles ulcerative colitis in humans. We studied epithelial transport and barrier function in IL-2(-/-) mice and used this model to characterize mechanisms of diarrhea during intestinal inflammation. (22)Na(+) and (36)Cl(-) fluxes were measured in proximal colon. Net Na(+) flux was reduced from 4.0 +/- 0.5 to 0.8 +/- 0.5 micromol.h(-1).cm(-2), which was paralleled by diminished mRNA and protein expression of the Na(+)/H(+) exchanger NHE3. Net Cl(-) flux was also decreased from 2.2 +/- 1.6 to -2.7 +/- 0.6 micromol.h(-1).cm(-2), indicating impaired Na(+)-Cl(-) absorption. In distal colon, aldosterone-induced electrogenic Na(+) absorption was 6.1 +/- 0.9 micromol.h(-1).cm(-2) in controls and was abolished in IL-2(-/-) mice. Concomitantly, mRNA expression of beta- and gamma-subunits of the epithelial sodium channel (ENaC) was reduced. Epithelial barrier was studied in proximal colon by impedance technique and mannitol fluxes. In contrast to ulcerative colitis, epithelial resistance was increased and mannitol fluxes were decreased in IL-2(-/-) mice. This was in accord with the findings of reduced ion transport as well as increased expression of tight junction proteins occludin and claudin-1, -2, -3, and -5. In conclusion, the IL-2(-/-) mucosa exhibits impaired electroneutral Na(+)-Cl(-) absorption and electrogenic Na(+) transport due to reduced mRNA and protein expression of NHE3 and ENaC beta- and gamma-subunit mRNA. This represents a model of early intestinal inflammation with absorptive dysfunction due to impaired transport protein expression/function while epithelial barrier is still intact. Therefore, this model is ideal to study regulation of transporter expression independent of barrier defects.

Animals↗
PubMed2004

Diagnosis of non-functioning neuro-endocrine gastro-enteropancreatic tumours.

Non-functioning neuro-endocrine gastro-enteropancreatic tumours are neoplasms of neuro-endocrine differentiation without symptoms of hormonal hypersecretion. In pancreatic tumours, symptoms are related to an expanding tumour mass, while most midgut tumours are small and symptoms of intermittent intestinal entrapment are due to mesenteric fibrosis. Positive somatostatin receptor imaging indicates the neuro-endocrine differentiation of the tumour. The high spatial resolution of MRI/CT improves preoperative planning. In localized pancreatic tumours, curative resection of the primary improves survival. In midgut tumours, resection of the primary should be performed, irrespective of the presence of liver metastases. Palliative surgery and cytoreductive therapy of liver metastases may prolong survival in both, pancreatic and midgut tumours. Combination chemotherapy is effective in pancreatic disease, while in midgut tumours the response rate is only 22%. As the antiproliferative effect of biotherapy is still uncertain, it cannot yet be recommended as a routine treatment in non-functioning neuro-endocrine gastro-enteropancreatic tumours.

Diagnostic Imaging↗
PubMed2003

Diagnosis of neuroendocrine tumours by retrospective image fusion: is there a benefit?

This study evaluated the use of image fusion in the preoperative staging of neuroendocrine tumors (NET) of the pancreas and the gastrointestinal tract (GIT). Thirty-eight patients suffering from a metastasized NET with location of the primary in the pancreas ( n=15) or the GIT ( n=23) were examined by somatostatin receptor scintigraphy (SRS) and computed tomography (CT). Consecutive image registration and fusion were performed using custom-built software integrated in AVS/Express (Advanced Visual Systems, Waltham, MA, USA). Registration was performed by a voxel-based algorithm based on normalized mutual information. Image fusion was feasible in 36/38 patients. A total of 87 foci were assigned to anatomical regions (e.g. gut, pancreas, liver, lymph node or others) by two independent observers in both SRS and SRS/CT fusion images. The assignments used a binary ranking system (1="definite", 0="not definite"). These results were then retrospectively compared to the classification of the foci, based on postoperative histology or clinical follow-up. Imaging by SRS allowed a definite anatomical assignment in 57% (50/87) and 61% (53/87) of all lesions in the case of observers A and B, respectively. Image fusion improved the topographic assignment to 91% (79/87) and to 93% (81/87). The number classified as "definite" by both observers increased from 54% (47/87) to 86% (77/87). The increase in definite assignments was highly significant for both observers ( P<0.0001 for each). In the case of foci classified as liver metastases, image fusion allowed improved assignment to the corresponding liver segment from 45% (18/40) to 98% (39/40) and from 58% (23/40) to 100% (40/40) by observers A and B, respectively. Furthermore, the improved assignment of foci classified as lesions by image fusion was relevant for therapy in 7/36 patients (19%). Therefore, the image fusion technique presented herein appears to be a very useful method for clinical routine.

Adult↗
PubMed2003

R-type Ca(2+)-channel activity is associated with chromogranin A secretion in human neuroendocrine tumor BON cells.

This electrophysiological study was undertaken to investigate the role of voltage-operated Ca(2+) channels (VOCCs) in cultivated human neuroendocrine tumor (NET) cells. Patch-clamp techniques, measurements of intracellular Ca(2+) ([Ca(2+)](i)), and secretion analysis were performed using cultured human NET BON cells. Ba(2+) inward currents through R-type channels (Ca(V)2.3) were measured and identified by SNX-482 (10 n M), a novel voltage-sensitive R-type Ca(2+) channel antagonist. In the presence of nifedipine (5 micro M), omega-Conotoxin GVIA (100 n M) and omega-Agatoxin IVA (20 n M), R-type channel currents were also detectable. Release of Ca(2+) from intracellular Ca(2+) stores by intracellular application of inositol-1,4,5-trisphosphate (InsP(3); 10 micro M) via the patch pipette during whole-cell configuration as well as induction of capacitative Ca(2+) entry (CCE), a passive maneuver to release Ca(2+) from intracellular Ca(2+) stores, led to an increase in [Ca(2+)](i). This effect could be reduced by SNX-482 (20 n M). In addition, SNX-482 (25 n M) also decreased chromogranin A (CgA) secretion, whereas omega-Conotoxin GVIA (500 n M) and nifedipine (5 micro M) failed to reduce CgA secretion. We conclude that these data reveal neuronal R-type channel activity (Ca(V)2.3), for the first time associated with CgA secretion in BON cells. Influx of Ca(2+) by activation of R-type channels may lead to an increase of intracellular Ca(2+), which stimulates CgA secretion. Thus, R-type channels could play an important role in certain clinical characteristics of NETs, such as the hypersecretion syndrome.

Barium↗
PubMed2003

Rescue therapy with tacrolimus is effective in patients with severe and refractory inflammatory bowel disease.

BACKGROUND: Oral tacrolimus, approved for the prophylaxis of organ rejection in liver or kidney transplants, has been reported to be effective in anecdotal cases of refractory inflammatory bowel disease. AIM: To evaluate the usefulness of low-dose oral tacrolimus in refractory inflammatory bowel disease. METHODS: Thirty-one adult Caucasian patients with steroid-dependent (n = 15) or steroid-refractory (n = 16) inflammatory bowel disease (Crohn's disease, n = 6; ulcerative colitis, n = 23; pouchitis, n = 2) were enrolled. Tacrolimus (0.1 mg/kg body weight per day) was administered orally in 30 patients and initially intravenously in one patient (0.01 mg/kg body weight per day), aiming for serum trough levels of 4-6 ng/mL. The median treatment duration was 12 months (range, 1-137 months). RESULTS: Twenty-eight patients (90.3%) experienced a clinical and laboratory response and 20 (64.5%) went into remission. One ulcerative colitis patient and two Crohn's disease patients did not improve. Three ulcerative colitis patients (9.7%) were colectomized at 1, 12 and 24 months after tacrolimus initiation. In 19 of 23 patients (82.6%) taking steroids, steroids were reduced or discontinued. Side-effects included a temporary rise of creatinine (n = 3, 9.7%), tremor or paraesthesias (n = 3, 9.7%), hyperkalaemia (n = 1, 3.2%), hypertension (n = 1, 3.2%) and an opportunistic infection (n = 1, 3.2%). CONCLUSION: Oral tacrolimus is safe and effective in refractory inflammatory bowel disease.

Administration, Oral↗
PubMed2003

Electrogastrography as a diagnostic tool for delayed gastric emptying in functional dyspepsia and irritable bowel syndrome.

Several pathophysiological mechanisms have been proposed in functional gastrointestinal (GI) disorders, e.g. altered GI motility and sensitivity. The aim of this study was to investigate gastric electrical activity (GEA) in patients with functional dyspepsia (FD) or irritable bowel syndrome (IBS) compared with healthy controls (HC), and to assess if abdominal symptoms and delayed gastric emptying are associated with alterations in GEA, as determined by electrogastrography (EGG). Forty patients with FD, IBS or both were compared with 22 HC. EGG was performed before and after a standard meal. Frequencies and amplitudes pre- and post-prandially were analysed. Furthermore, gastric emptying and symptom scores were assessed. Eight of 40 patients (20%; three FD, three IBS, two FD and IBS) had delayed gastric emptying. Disturbed gastric emptying and lack of a postprandial increase in the EGG amplitude were significantly correlated (r = 0.8; P < 0.005). No differences between controls and patients were observed in the distribution of EGG frequencies. Treatment with the prokinetically active macrolide erythromycin improved gastric emptying, GEA and symptoms (n = 4). The data suggest that EGG could be useful as a diagnostic tool in patients with FD and IBS to identify a subgroup of patients with delayed gastric emptying.

Adolescent↗
PubMed2003

Complete bile duct sequestration after liver transplantation, caused by ischemic-type biliary lesions.

Ischemic-type biliary lesions (ITBLs) are the most frequent cause of nonanastomotic biliary strictures in liver grafts, affecting about 2-19 % of patients after liver transplantation. ITBL is characterized by bile duct destruction, subsequent stricture formation, and sequestration. We report here the case of a patient affected by extremely severe ITBL, with sequestration and disintegration of the entire bile duct system, in which it was possible to extract the complete biliary tree endoscopically in a single piece. Histological examination revealed that all cells of the bile duct wall had been destroyed within 3 months after liver transplantation and replaced by connective tissue. Subsequently, biliary stricture formation occurred at the hepatic hilum, as well as the adjacent large bile ducts. It may be hypothesized that cellular rejection of small bile ducts leads to the vanishing bile duct syndrome, whereas cellular rejection of large bile ducts results in ITBL. The strictures were repeatedly dilated by endoscopic means, allowing successful control of stricture formation, as well as maintenance of liver function. At the time of writing, the grafted organ and the patient had survived for more than 3 years in good health. This is the first detailed report on a sequestration of the entire bile duct system caused by ITBL, successfully treated for several years by endoscopic means.

Bile Duct Diseases↗
PubMed2003

[Biologic therapy of inflammatory bowel disease].

Biological therapies in inflammatory bowel disease reflect the exponential advancement in understanding the human intestinal immune system and particularly the biology of intestinal inflammation during the past decade. The better understanding of the mechanisms of inflammatory bowel disease has evolved from desriptive clinical data and genetically engineered animal models. It led to great interest in the evaluation of a variety of new therapeutic agents with novel actions. This review will discuss the mechanisms of biologicals (antibodies against pro-inflammatory cytokines, T cell antibodies, anti-inflammtory cytokines, adhesion molecule blockers, growth factors, hormones, colony stimulating factors, fusion proteins, anti-sense oligonucleotides, trefoil peptides, immunostimulatory [ISS] DNA) used in the treatment of inflammatory bowel disease and summarizes the available data on established biologic therapies as well as investigational agents and briefly touch on probiotics. Based on the data discussed, it seems that biologicals will play an important role in managing inflammatory bowel disease in the near future.

Animals↗
PubMed2003

Autocrine growth inhibition by transforming growth factor beta-1 (TGFbeta-1) in human neuroendocrine tumour cells.

BACKGROUND AND AIM: The role of transforming growth factor beta-1 (TGFbeta-1) in neuroendocrine tumour biology is currently unknown. We therefore examined the expression and biological significance of TGFbeta signalling components in neuroendocrine tumours (NETs) of the gastroenteropancreatic (GEP) tract. METHODS: Expression of TGFbeta-1 and its receptors, Smads and Smad regulated proteins, was examined in surgically resected NET specimens and human NET cell lines by immunohistochemistry, reverse transcriptase-polymerase chain reaction, immunoblotting, and ELISA. Activation of TGFbeta-1 dependent promoters was tested by transactivation assays. Growth regulation was evaluated by cell numbers, soft agar assays, and cell cycle analysis using flow cytometry. The role of endogenous TGFbeta was assessed by a TGFbeta neutralising antibody and stable transfection of a dominant negative TGFbetaR II receptor construct. RESULTS: Coexpression of TGFbeta-1 and its receptors TGFbetaR I and TGFbetaR II was detected in 67% of human NETs and in all three NET cell lines examined. NET cell lines expressed the TGFbeta signal transducers Smad 2, 3, and 4. In two of the three cell lines, TGFbeta-1 treatment resulted in transactivation of a TGFbeta responsive reporter construct as well as inhibition of c-myc and induction of p21((WAF1)) expression. TGFbeta-1 inhibited anchorage dependent and independent growth in a time and dose dependent manner in TGFbeta-1 responsive cell lines. TGFbeta-1 mediated growth inhibition was due to G1 arrest without evidence of induction of apoptosis. Functional inactivation of endogenous TGFbeta revealed the existence of an autocrine antiproliferative loop in NET cells. CONCLUSIONS: Neuroendocrine tumour cells of the gastroenteropancreatic tract are subject to paracrine and autocrine growth inhibition by TGFbeta-1, which may account in part for the low proliferative index of this tumour entity.

Autocrine Communication↗
PubMed2002

[Acute liver failure following the use of ecstasy (MDMA)].

The use of "ecstasy" (Methylenedioxymethamphetamine) as a recreational drug is increasing in europe since the 1980's. Aside intended psychological effects the use of ecstasy can be followed by symptoms of intoxication; complications include toxic hepatic damage up to acute hepatic failure. This case-report is about a 17-year old female patient who regularly used "ecstasy" over a six-month period. Two days after the last use of "ecstasy", she reported to her general practitioner with nausea, vomiting, abdominal pain and jaundice. Within 10 days the patient developed acute liver failure. With criteria for liver transplantation fulfilled she was listed for orthotopic liver transplantation of high urgency which was carried out only one day later. Histological examination of the explanted liver showed evidence for a toxic fulminant hepatitis. After transplantation the patient made a full recovery and was released from hospital on day 26 after transplantation. At the first control after six months the patient was in good physical and nutritional condition, serological parameters were normal and ultrasound examination of the transplanted liver was unremarkable. The ethiopathology of "ecstasy"-induced hepatotoxicity, which can occur dose-independently with a symptom-free period from days to weeks after ingestion is not yet fully understood. Possible mechanisms of hepatic damage include influence of MDMA on body temperature regulation, harmful effects of the substance or further components of the "ecstasy"-tablets on the liver cell or a genetic vulnerability of some individuals against amphetamines and amphetamine derivates. There are no parameters existing which could predict the course and severity of "ecstasy"-induced hepatopathy. Especially in young patients with symptoms of hepatic damage frequent controls of clinical status and relevant laboratory parameters are of great importance. Patient transfer to a specialised centre should follow as early as possible; at the latest, when coagulopathy occurs.

Adolescent↗
PubMed2002

Functional relevance of activin A in the intestinal epithelium.

BACKGROUND: Activin A modulates inflammation and repair in various tissues. The aim of this study was to characterize the effects of activin A on intestinal epithelial cell function and to evaluate a potential role in intestinal epithelial wound repair and inflammation. METHODS: The expression of activin A and its receptors ActRI and ActRII in intestinal epithelial IEC-6 cells and in tissues from IBD patients and non-inflamed controls was evaluated using RT-PCR and immunohistochemistry. Functional effects of activin A on intestinal epithelial cell migration and proliferation were assessed using an in vitro wounding model and colorimetric MTT assays. RESULTS: Expression of the activin betaA subunit and the activin receptors ActRI and ActRII in IEC-6 cells was demonstrated using RT-PCR. Activin A (50 ng/ml) caused a significant, on average 2.8-fold enhancement of epithelial cell migration and a significant on average 4.1-fold inhibition of IEC-6 cell proliferation. Expression of ActRI and ActRII was observed in all intestinal tissues from patients with IBD and in all controls. In contrast, no expression of the activin betaA-subunit was observed in controls, while betaA expression was found in intestinal tissues from IBD patients. CONCLUSIONS: Activin A may play an important role in the modulation of intestinal epithelial cell function, thus providing a new approach to modulate intestinal wound repair.

Activin Receptors↗
PubMed2002

Neuroendocrine tumors of the gastro-entero-pancreatic system: the role of early diagnosis, genetic testing and preventive surgery.

Surgery is the only curative approach in neuroendocrine gastro-entero-pancreatic (GEP) tumors. As cure is highly dependent of tumor size, early diagnosis is a prerequisite for surgical success. Diagnosis of nonfunctioning tumors of the pancreas or midgut origin is due to symptoms related to the tumor burden, thus early diagnosis is mostly incidental. Functioning pancreatic tumors should be operated early in the course of the disease to provide cure. No genetic screening is available for sporadic GEP tumors. In patients with MEN-1 syndrome genetic screening is recommended to restrict the burden of clinical screening to those with positive test results. Due to the nature of the disease cure may not be achieved, however prevention of cancer may be obtained for one or two decades of life, especially in patients with gastrinoma or nonfunctioning tumors.

Digestive System Neoplasms↗