0000000000019549
AUTHOR
Martin H. Holtmann
showing 20 related works from this author
Noninvasive assessment of Crohn's disease activity: a comparison of 18F-fluorodeoxyglucose positron emission tomography, hydromagnetic resonance imag…
2002
Detection of disease activity in Crohn's disease (CD) is of crucial importance for diagnosis and management of the disease. Noninvasive methods for monitoring are desirable and comprise hydromagnetic resonance imaging (hydro-MRI) and leukocyte scintigraphy. In addition, a recent case report indicated the potential of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) to assess CD activity. However, comparative prospective studies are lacking.Between February, 1999 and August, 2000, 59 patients with CD were enrolled in a prospective study to assess disease activity by FDG-PET, hydro-MRI, and immunoscintigraphy with anti-nonspecific cross-reacting antigen 95 antigranulocyte antibod…
Differential TNF-Signaling in Chronic Inflammatory Disorders
2004
TNF-alpha is a pleiotropic cytokine with strong proinflammatory and immunomodulatory properties. TNF-alpha plays a critical role in many acute or chronic inflammatory diseases and anti-TNF-strategies have proven to be clinically effective. Two TNF-specific cell surface receptors TNF-R1 and TNF-R2 have been identified and the function of these receptors and the downstream intracellular signal transduction pathways have been extensively studied in vitro. For a long time TNF-R1 was considered to be the predominant mediator of TNF-signaling, whereas TNF-R2 was ascribed only auxilliary function. However, there is increasing clinical and experimental evidence for an important independent role of …
Anti-TNF-Antikörper zur Therapie von entzündlichen Darmstenosen bei Morbus Crohn
2003
Stenoses are a frequent complication in patients with Crohn's disease and represent a major diagnostic and therapeutic challenge. The proper assessment of the nature of a stenosis as inflammatory or fibrotic is critical for appropriate treatment, since symptomatic fibrotic stenoses require surgical resection. Standard diagnostic procedures to assess the nature of a stenosis include endoscopy, conventional contrast radiography and magnetic resonance tomography. Recent data suggest, that the positron-emission-tomography possesses a high sensitivity and specificity to confirm inflammatory activity in the bowel. The recombinant monoclonal anti-TNF-antibody Infliximab (Remicade) has been approve…
Tonnenkonkremente im Ductus choledochus bei einer 4 Jahre vergessenen, impaktierten Endoprothese
2006
We report on a 67-year-old female patient who presented in July 2005 with sudden onset of pain in the right upper abdomen. The patient had undergone cholecystectomy in 1987. Because of recurrrent complaints in the right upper abdomen, a pigtail stent was placed into the common hepatic duct in 2001. When the patients presented now, the laboratory tests including liver enzymes were within normal ranges. Endoscopic retrograde cholangiogi aphy, however, revealed a remaining 10-French, impacted double pigtail endoprothesis that was obstructed by sludge as well as multiple giant bile duct stones of 20 to 30 mm in size. The giant stones could be finally removed by the combined use of ESWL and endo…
From Immunogenic Mechanisms to Novel Therapeutic Approaches in Inflammatory Bowel Disease
2006
Crohn’s disease (CD) and ulcerative colitis (UC) are the two most common forms of chronic inflammatory bowel disease (IBD). The etiology of IBD is still unclear and should be considered as multi-factorial according to recent studies.1 Genetic factors seem to play a pathogenetic role as well as environmental, infectious and immulogical factors. Substantial progress, however, has been made in the understanding of the pathogenesis of IBD during the past years persuing the view, that IBD could result from disturbances of the intestinal barrier and a pathologic activation of the intestinal immune response towards luminal, bacterial antigens. This paradigm has led to the identification of key pla…
Ausbildung am Ultraschallsimulator – Analyse der größten simulatorbasierten Fortbildung in Deutschland
2010
Teaching ultrasound (US) has not been sufficiently standardised yet. Most educational devices in US consist of 2-dimensional B-mode images. However, the identification of anatomic structures in the 3-dimensional space can only be learned by practical hands-on education. In US simulators, US images of real pathologies are created by the examination of a dummy with a mock transducer. The resulting US images were previously recorded in a 3-dimensional format and were processed in a way which facilitates the reconstruction and projection of the images on a screen corresponding to the sectional plane of the mock transducer, simulating the conventional B-mode images. This enables standardised, re…
Coexpression of receptor-tyrosine-kinases in gastric adenocarcinoma-a rationale for a molecular targeting strategy?
2007
AIM: To define the (co-)expression pattern of target receptor-tyrosine-kinases (RTK) in human gastric adenocarcinoma. METHODS: The (co-)expression pattern of VEGFR1-3, PDGFRα/β and EGFR1 was analyzed by RT-PCR in 51 human gastric adenocarcinomas. In addition, IHC staining was applied for confirmation of expression and analysis of RTK localisation. RESULTS: The majority of samples revealed a VEGFR1 (98%), VEGFR2 (80%), VEGFR3 (67%), PDGFRα (82%) and PDGFRβ (82%) expression, whereas only 62% exhibited an EGFR1 expression. 78% of cancers expressed at least four out of six RTKs. While VEGFR1-3 and PDGFRα revealed a predominantly cytoplasmatic staining in tumor cells, accompanied by an additiona…
Methylene blue-aided chromoendoscopy for the detection of intraepithelial neoplasia and colon cancer in ulcerative colitis.
2003
Timely diagnosis of intraepithelial neoplasias (IN) and colitis-associated colon carcinomas (CRC) is crucially important for the treatment of ulcerative colitis (UC). We performed a randomized, controlled trial to test whether chromoendoscopy (CE) might facilitate early detection of IN and CRC in UC.A total of 263 patients with long-standing UC (or=8 years) were screened for potential inclusion in the study, 165 of whom were randomized at a 1:1 ratio to undergo conventional colonoscopy or colonoscopy with CE using 0.1% methylene blue. Five mucosal biopsy specimens were taken every 10 cm between the rectum and cecum. Circumscript lesions in the colon were evaluated according to a modified pi…
Tumor necrosis factor-receptor 2 is up-regulated on lamina propria T cells in Crohn's disease and promotes experimental colitis in vivo
2002
Tumor necrosis factor (TNF) plays a pivotal role in the pathogenesis of Crohn's disease (CD). However, little is known about the role of TNF receptors (TNF-R) in this disease. Here, we found that TNF-R2 (in contrast to TNF-R1) was significantly up-regulated on lamina propria and peripheral blood T cells in CD compared to control patients. To directly test the functional role of TNF-R2 in Th1-mediated experimental colitis in vivo, we took advantage of transgenic animals overexpressing TNF-R2 in T cells. Reconstitution of SCID mice with CD4+ CD62L+ T cells from TNF-R2 transgenic mice led to an earlier wasting syndrome, a more severe colitis and augmented Th1 cytokine production than reconstit…
Blockade of interleukin 6 trans signaling suppresses T-cell resistance against apoptosis in chronic intestinal inflammation: Evidence in Crohn diseas…
2000
The pro-inflammatory cytokine interleukin (IL)-6 (refs. 1-5) can bind to cells lacking the IL-6 receptor (IL-6R) when it forms a complex with the soluble IL-6R (sIL-6R) (trans signaling). Here, we have assessed the contribution of this system to the increased resistance of mucosal T cells against apoptosis in Crohn disease (CD), a chronic inflammatory disease of the gastrointestinal tract. A neutralizing antibody against IL-6R suppressed established experimental colitis in various animal models of CD mediated by type 1 T-helper cells, by inducing apoptosis of lamina propria T cells. Similarly, specific neutralization of sIL-6R in vivo by a newly designed gp130-Fc fusion protein caused suppr…
Immunotherapeutic approaches to inflammatory bowel diseases
2001
For a long time corticosteroids, aminosalicylic acid preparations and antibiotics have represented the principal approaches in evidence-based drug therapy for chronic inflammatory bowel diseases (IBD), e.g., Crohn's disease (CD) and ulcerative colitis (UC), and are able to suppress disease activity in most cases. However, there are cases that do not respond to conventional drug therapy or remain dependent on high doses of steroids associated with severe side effects in the long run. It is generally accepted now that IBD has an immunological basis and results from a hyperresponsive state of the intestinal immune system. Although the primary etiological defect respectively immunogenic agent s…
Transplanting the genetic susceptibility to Crohn’s disease
2003
Susceptibility to Crohn’s disease may be transferred via haematopoietic stem cells, highlighting the pivotal role of genetic factors in the pathogenesis of Crohn’s disease Crohn’s disease (CD) is one of the two most common forms of inflammatory bowel disease (IBD). The prevalence of CD has increased in Western countries over the past decades and mainly young patients are affected, with a peak incidence between 15 and 35 years.1 The aetiology of IBD is still unclear and should be considered as multifactorial according to recent studies.2 Genetic factors seem to play a pathogenic role as well as environmental, infectious, and immunological factors. All of these different aetiological aspects …
Functional relevance of soluble TNF-alpha, transmembrane TNF-alpha and TNF-signal transduction in gastrointestinal diseases with special reference to…
2002
As a result of extensive clinical and basic research, the pivotal role of tumour necrosis factor (TNF) in the pathogenesis of chronic inflammatory diseases such as inflammatory bowel disease (IBD) has now generally been acknowledged. This has led to promising clinically effective anti-TNF-strategies. Of note, there is more and more evidence that TNF seems to play a key role in other gastrointestinal diseases including Helicobacter pylori infection, pancreatitis, viral hepatitis and toxic liver damage, too. The action of TNF at the cellular level is mediated by two cell surface receptors, TNF-R1 (p60) and TNF-R2 (p80). The function of these receptors and the downstream intracellular signal t…
CD28-dependent Rac1 activation is the molecular target of azathioprine in primary human CD4+ T lymphocytes
2003
Azathioprine and its metabolite 6-mercaptopurine (6-MP) are immunosuppressive drugs that are used in organ transplantation and autoimmune and chronic inflammatory diseases such as Crohn disease. However, their molecular mechanism of action is unknown. In the present study, we have identified a unique and unexpected role for azathioprine and its metabolites in the control of T cell apoptosis by modulation of Rac1 activation upon CD28 costimulation. We found that azathioprine and its metabolites induced apoptosis of T cells from patients with Crohn disease and control patients. Apoptosis induction required costimulation with CD28 and was mediated by specific block- ade of Rac1 activation thro…
VEGF-D expression correlates with colorectal cancer aggressiveness and is downregulated by cetuximab
2008
AIM: To gain mechanistic insights into the role played by epidermal growth factor receptor (EGFR) in the regulation of vascular endothelial growth factors (VEGFs) in colorectal cancer (CRC). METHODS: The impact of high-level expression of the growth factor receptors EGFR and VEGF receptor (VEGFR)3 and the VEGFR3 ligands VEGF-C and VEGF-D on disease progression and prognosis in human CRC was investigated in 108 patients using immunohistochemistry. Furthermore, the expression of the lymphangiogenic factors in response to the modulation of EGFR signalling by the EGFR-targeted monoclonal antibody cetuximab was investigated at the mRNA and protein level in human SW480 and SW620 CRC cell lines an…
Das mukosale Immunsystem
2002
Untersuchungen der letzten 10 Jahre haben zu einem verbesserten Verstandnis der Pathophysiologie von chronisch entzundlichen Darmerkrankungen gefuhrt. Neuere Studien belegen hierbei v. a. die funktionelle Bedeutung einer Aktivierung des mukosalen Immunsystems durch bakterielle Antigene fur die Pathogenese der chronisch entzundlichen Darmerkrankungen (CED). Neben Chemokinen und Adhasionsmolekulen scheinen vor allem Zytokine, die von antigenprasentierenden Zellen und T-Lymphozyten produziert werden, pathogenetisch fur die CED von entscheidender Bedeutung zu sein. So konnte tierexperimentell gezeigt werden, dass Antikorper gegen proinflammatorische Zytokine zu einer Suppression von chronisch i…
Recurrent gastrointestinal haemorrhage from the distal duodenum
2006
In October 2004, a 69 year female patient presented with melena and anaemia (haemoglobin level 9 g/dl). The patient had been on warfarin due to construction of an aorto-bifemoral graft because of an aortic aneurysm and an …
T helper cell polarisation in coeliac disease: any (T-)bet ?
2004
Recent data strongly support the view that coeliac disease is a Th1 mediated inflammatory disease as both interferon γ production and T-bet levels in gut infiltrating cells are upregulated The puzzling observation on high interferon γ (IFN-γ) but low interleukin (IL)-12 levels in coeliac disease (CD) has resulted in questions about the underlying principles of T helper cell polarisation. In this issue of G ut ,1 the molecular basis of T helper cell polarisation in CD has been illuminated by the finding that T-bet, the master transcription factor of T helper cell type 1 (Th1) cells, is upregulated in this disease [see page 1090] . The past decade has witnessed a dramatic improvement in our p…
In-vivo confocal real-time mini-microscopy in animal models of human inflammatory and neoplastic diseases
2007
Background and study aims Although various improvements in tissue imaging modalities have recently been achieved, in-vivo molecular and subsurface imaging in the field of gastroenterology remains a technical challenge. In this study we evaluated a newly developed, handheld, miniaturized confocal laser microscopy probe for real-time in-vivo molecular and subsurface imaging in rodent models of human disease. Materials and methods The minimicroscope uses a 488-nm, single line laser for fluorophore excitation. The optical slice thickness is 7 microm, the lateral resolution 0.7 microm. The range of the z-axis is 0-250 microm below the tissue surface. Imaging was performed using different fluores…
Gastroenterologische Palliativmedizin
2008
On consideration of current medical and socio-economical factors, palliative care is becoming an increasingly important aspect of modern medicine in Germany. The German Society for Digestive and Metabolic Disorders (DGVS) has taken this into account by founding the working group "Palliative Gastroenterology". Patients with gastrointestinal malignancies or advanced non-malignant liver disease represent an important group that benefits from palliative care. Approximately 80 % of all palliative care patients suffer from gastrointestinal symptoms and endoscopic procedures performed by gastroenterologists play an important role in relieving symptoms such as obstruction. It is the object of this …