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Martin Zeitz

Publications and source records attributed to Martin Zeitz.

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

The solvent-inaccessible Cys67 residue of HLA-B27 contributes to T cell recognition of HLA-B27/peptide complexes.

Crystallographic studies have suggested that the cysteine at position 67 (Cys(67)) in the B pocket of the MHC molecule HLA-B*2705 is of importance for peptide binding, and biophysical studies have documented altered thermodynamic stability of the molecule when Cys(67) was mutated to serine (Ser(67)). In this study, we used HLA-B27.Cys(67) and HLA-B27.Ser(67) tetramers with defined T cell epitopes to determine the contribution of this polymorphic, solvent-inaccessible MHC residue to T cell recognition. We generated these HLA-B27 tetramers using immunodominant viral peptides with high binding affinity to HLA-B27 and cartilage-derived peptides with lower affinity. We demonstrate that the yield of refolding of HLA-B27.Ser(67) molecules was higher than for HLA-B27.Cys(67) molecules and strongly dependent on the affinity of the peptide. T cell recognition did not differ between HLA-B27.Cys(67) and HLA.B27.Ser(67) tetramers for the viral peptides that were investigated. However, an aggrecan peptide-specific T cell line derived from an HLA-B27 transgenic BALB/c mouse bound significantly stronger to the HLA-B27.Cys(67) tetramer than to the HLA-B27.Ser(67) tetramer. Modeling studies of the molecular structure suggest the loss of a SH ... pi hydrogen bond with the Cys-->Ser substitution in the HLA-B27 H chain which reduces the stability of the HLA-B27/peptide complex. These results demonstrate that a solvent-inaccessible residue in the B pocket of HLA-B27 can affect TCR binding in a peptide-dependent fashion.

Aggrecans↗
PubMed2004

Standards of medical treatment and nutrition in Crohn's disease.

Crohn's disease is a condition of chronic inflammation potentially involving any location of the alimentary tract from mouth to anus but with a propensity for the distal small bowel and proximal large bowel. Frequent complications include stricture and fistula. Numerous extra-intestinal manifestations may also be present. The aetiology of Crohn's disease is incompletely understood, and therapy, although generally effective in alleviating the symptoms, is not curative. Due to the heterogeneity of the disease a major need for the therapeutic approach is the ability to define subgroups with distinct characteristics. However, with regard to the heterogeneity of demographic, anatomic and disease behaviour characteristics, distillation of the numerous possible phenotypes in simple categories is a formidable task. In the present review the focus will be on clinically relevant situations providing therapeutic algorithms according to international guidelines.

Algorithms↗
PubMed2004

Gallbladder involvement of Henoch-Schönlein purpura mimicking acute acalculous cholecystitis.

BACKGROUND/AIMS: We report the case of a 53-year-old man with fever and severe abdominal pain following an upper respiratory tract infection. METHODS/RESULTS: The clinical signs, the laboratory markers, and the ultrasound findings were consistent with acute acalculous cholecystitis and he underwent cholecystectomy. Histologically the gallbladder showed vasculitis and the patient developed postoperatively a purpuric rash of the legs with transient ankle arthritis. Gastroscopy revealed prepyloric ulcers consistent with vasculitis. The patient was diagnosed as having Henoch-Schönlein purpura. Gastric ulcers as well as arthritis disappeared upon treatment with corticosteroids and proton pump inhibitors. CONCLUSION: Taken together, Henoch-Schönlein purpura can mimic acute cholecystitis and should be considered as a rare differential diagnosis of acute cholecystitis.

Abdominal Pain↗
PubMed2004

Development of intestinal inflammation in double IL-10- and leptin-deficient mice.

Leptin-deficient (ob/ob) mice are resistant in different models of autoimmunity and inflammation, suggesting that leptin regulates immunity and inflammation. To investigate whether leptin deficiency modulates the spontaneous intestinal inflammation observed in interleukin (IL)-10-deficient mice, double IL-10- and leptin-deficient [IL-10 knockout (KO) ob/ob] mice were generated and compared with single IL-10 KO mice for colitis severity. Body weight in IL-10 KO ob/ob mice was significantly reduced compared with that of ob/ob mice. However, when compared with wild-type or IL-10 KO mice, IL-10 KO ob/ob mice were still markedly obese. IL-10 KO and IL-10 KO ob/ob mice developed colitis with a comparable time-course and severity in terms of macroscopic and histologic scores. Likewise, production of interferon-gamma, IL-6, and IL-13 from colon cultures and splenocytes did not differ among these two groups. Conversely, rates of apoptosis were higher in lamina propria lymphocytes obtained from the colon of IL-10 KO ob/ob compared with IL-10 KO mice. In conclusion, although leptin deficiency has been associated with resistance in models of autoimmunity and inflammation induced by exogenous stimuli, leptin appears not to play a significant role in the spontaneous colitis of IL-10 KO mice, although it modulates survival of intestinal lymphocytes.

Animals↗
PubMed2004

Enhancement of peripheral benzodiazepine receptor ligand-induced apoptosis and cell cycle arrest of esophageal cancer cells by simultaneous inhibition of MAPK/ERK kinase.

Specific ligands of the peripheral benzodiazepine receptor (PBR) activate pro-apoptotic and anti-proliferative signaling pathways. Previously, we found that PBR ligands activated the p38 mitogen-activated protein kinase (MAPK) pathway in esophageal cancer cells, and that the activation of p38MAPK contributed to tumor cell apoptosis and cell cycle arrest. Here, we report that PBR ligands also activate the pro-survival MAPK/ERK kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway in esophageal cancer cells, which might compromise the efficacy of PBR ligands. Hence, a combination treatment of PBR ligands and MEK inhibitors, which are emerging as promising anticancer agents, was pursued to determine whether this treatment could lead to enhanced apoptosis and cell cycle arrest. Using Western blotting we demonstrated a time- and dose-dependent phosphorylation of ERK1/2 in response to PBR ligands. Apoptosis was investigated by assessment of mitochondrial alterations and caspase-3 activity. Cell cycle arrest was measured by flow cytometric analysis of stained isolated nuclei. The inhibition of MEK/ERK with a pharmacologic inhibitor, 2'-amino-3'-methoxyflavone (PD 98059), resulted in a synergistic enhancement of PBR-ligand-induced growth inhibition, apoptosis and cell cycle arrest. Specifity of the pharmacologic inhibitor was confirmed by the use of 1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio)butadiene (U 0126), a second MEK/ERK inhibitor, and 1,4-diamino-2,3-dicyano-1,4-bis(methylthio)butadiene (U 0124), a structural analogue of it which does not display any affinity to MEK. Enhanced pro-apoptotic and anti-proliferative effects were observed both in KYSE-140 esophageal squamous cancer and OE-33 adenocarcinoma cells, suggesting that this effect was not cell-type specific. In addition, the PBR-mediated overexpression of the stress response gene (growth arrest and DNA-damage-inducible gene gadd153) was synergistically enhanced by MEK inhibition. This is the first report of enhanced PBR-ligand-mediated apoptosis and cell cycle arrest by simultaneous MEK inhibition, suggesting a new anticancer strategy.

Apoptosis↗
PubMed2004

IL-1beta and TNFalpha regulate sodium absorption in rat distal colon.

The epithelial Na+ channel (ENaC) provides the main absorptive pathway of the distal large intestine. This study aimed to characterize regulatory influences of cytokines in rat late distal colon. After 6 h incubation with either IL1beta, TNFalpha, IFNgamma, or combinations of TNFalpha and IFNgamma, ENaC was measured as electrogenic Na+ transport after 8 h induction by 3 nM aldosterone (JNa) in totally stripped specimens in the Ussing chamber. Subsequently, alpha-, beta-, and gamma-ENaC subunit mRNAs were analyzed by Northern blotting. The gamma-ENaC promoter was cloned and characterized by reporter gene assays. IL-1beta and TNFalpha, but not interferon-gamma, decreased JNa. In parallel, beta- and gamma-ENaC transcription was inhibited, whereas alpha-ENaC was unaffected. gamma-ENaC promoter activity was inhibited by IL-1beta and TNFalpha but not by IFNgamma. We conclude that the pro-inflammatory cytokines IL-1beta and TNFalpha inhibit electrogenic sodium absorption in rat distal colon by mRNA expression regulation of the beta- and gamma-ENaC subunits.

Aldosterone↗
PubMed2004

Esophageal cancer.

Explore the source record for details and available documents.

Carcinoma, Squamous Cell↗
PubMed2004

Peripheral benzodiazepine receptor ligands induce apoptosis and cell cycle arrest in human hepatocellular carcinoma cells and enhance chemosensitivity to paclitaxel, docetaxel, doxorubicin and the Bcl-2 inhibitor HA14-1.

BACKGROUND/AIMS: Hepatocellular carcinoma (HCC) is one of the most common causes of cancer deaths worldwide. Thus, novel therapies are urgently needed. A promising approach is the use of peripheral benzodiazepine receptor (PBR) ligands which inhibit the proliferation of various tumors. METHODS: PBR expression both in human HCC cell lines and in tumor specimens of HCC patients was analyzed by RT-PCR and immunostaining. To evaluate PBR ligands for the treatment of HCC, we tested their effects on human HCC cells. RESULTS: PBR was localized to the mitochondria both of HCC cell lines and tumor tissues of HCC patients. In contrast, normal liver did not express PBR. PBR ligands inhibited the proliferation of HCC cell lines by inducing apoptosis and cell cycle arrest. Apoptosis was characterized by a breakdown of the mitochondrial membrane potential, caspase-3 activation and nuclear degradation. Furthermore, pro-apoptotic Bax was overexpressed while anti-apoptotic Bcl-2 and Bcl-X(L) were suppressed. Cell cycle was arrested both at the G1/S- and G2/M-checkpoints. Synergistic anti-neoplastic effects were obtained by a combination of PBR ligands with cytostatic drugs (paclitaxel, docetaxel, doxorubicin), or with an experimental Bcl-2 inhibitor. CONCLUSIONS: This is the first report on the induction of apoptosis and cell cycle arrest by PBR ligands in HCC cells. Moreover, PBR ligands sensitized HCC cells to taxans and doxorubicin.

Antibiotics, Antineoplastic↗
PubMed2004

Targeting the epidermal growth factor receptor by gefitinib for treatment of hepatocellular carcinoma.

BACKGROUND/AIMS: Hepatocellular carcinoma (HCC) is one of the most common cancer-related causes of death worldwide. Due to very poor 5-year-survival new therapeutic approaches are mandatory. Gefitinib, an inhibitor of epidermal growth factor receptor tyrosine kinase (EGFR-TK), potently suppresses the growth of various tumors, but its effect on HCC remains unexplored. We therefore studied the antineoplastic potency of gefitinib in human HCC cells. RESULTS: Gefitinib induced a time- and dose-dependent growth inhibition of the human HCC cell lines Huh-7 and HepG2. Gefitinib-treatment induced both mitochondria-dependent and -independent apoptosis. Changes in mitochondrial membrane potential and caspase-8 activation, followed by caspase-3 activation and nuclear degradation, were detected. Moreover, gefitinib induced cell cycle arrest at the G1/S checkpoint and decreased the phosphorylation of mitogen-activated protein kinase ERK1/2. Finally, gefitinib suppressed the expression of antiapoptotic Bcl-2 and Bcl-X(L), further rendering HCC cells prone to apoptosis. CONCLUSIONS: Our data demonstrate that the inhibition of EGFR-TK by gefitinib induced growth inhibition, apoptosis and cell cycle arrest in human HCC cells. Thus, EGFR-TK inhibition appears to be a promising novel approach for future treatment strategies of HCC.

Antineoplastic Agents↗
PubMed2004

Cytokine-dependent transcriptional down-regulation of epithelial sodium channel in ulcerative colitis.

BACKGROUND & AIMS: The main limiting factor for sodium absorption in distal colon is the amiloride-sensitive epithelial sodium channel (ENaC). This study aimed to characterize mechanisms involved in the dysregulation of ENaC expression in ulcerative colitis (UC). METHODS: Epithelial preparations from surgically removed inflamed and control sigmoid colons were used. Active electrogenic Na(+) transport (J(Na)) was determined after 8-hour aldosterone stimulation in Ussing-chambers (corrected for the altered epithelial/subepithelial resistance ratio). Subsequently, ENaC alpha-, beta-, and gamma-subunits were analyzed immunohistochemically and in Western and Northern blots (corrected for the inflammatory increase in subepithelial protein content). To study gene regulation, the promoters of beta- and gamma-ENaC were analyzed in reporter gene assays. RESULTS: In controls, aldosterone stimulated J(Na) and induced ENaC beta- and gamma-subunit expression, whereas this response was virtually abolished in UC. Preservation of surface epithelium in UC was indicated by unchanged ENaC alpha-subunit expression, which points also against a mere immaturity or epithelial cell loss. Inhibition of electrogenic sodium transport as well as beta- and gamma-ENaC mRNA expression could be mimicked in control colon by in vitro preexposure for 8 hours to tumor necrosis factor alpha and interferon gamma. Promoter analysis revealed that down-regulation of beta- and gamma-ENaC gene expression was primarily induced by tumor necrosis factor alpha. CONCLUSIONS: We conclude that, in UC, elevated proinflammatory cytokines selectively impair beta- and gamma-ENaC expression, which contributes to diarrhea by reducing colonic sodium absorption.

Antineoplastic Agents↗
PubMed2004

Heterogeneous expression of neuroendocrine marker proteins in human undifferentiated carcinoma of the colon and rectum.

The expression of neuroendocrine marker proteins in undifferentiated colorectal cancers has not yet been studied in great detail. Therefore, the survival of 20 patients with small cell undifferentiated colorectal cancers treated at our institution between 1982 and 1997 (0.8% of all operated colorectal carcinomas) was correlated with the extent of neuroendocrine differentiation. Chromogranin A, synaptophysin, syntaxin1, VAMP2, SNAP25, and alpha/beta-SNAP were used as neuroendocrine markers. Based on the degree of immunoreactivity for these marker proteins, tumors were divided into group 0 (<2% cells stained positive for neuroendocrine markers) and group 1 (>2% cells stained positive). Patients were followed up for at least 5 years or until death. Nine of twenty (45%) undifferentiated colorectal tumors expressed neuroendocrine markers (group 1). Only one patient of this group survived 2 years (11%), whereas the 2-year survival rate was 45.4% in group 0. Nine of eleven patients of group 0 were diagnosed in UICC stage I-III, whereas eight of nine tumors with expression of neuroendocrine markers were diagnosed in UICC stage IV (P = 0.002). Our results show that neuroendocrine differentiation is often seen in small cell undifferentiated colorectal cancer. It correlates with a more aggressive course of the disease.

Adult↗
PubMed2003

Adult autoimmune enteropathy treated successfully with tacrolimus.

BACKGROUND: Autoimmune enteropathy is a life-threatening, chronic disease of the small bowel mucosa, which generally responds well to steroids. Treatment requires long-term immunosuppression, and steroid-sparing treatment strategies are desirable. Azathioprine and cyclosporine A have limitations, however alternatives have not been described in adults. CASE REPORT: We present the case of a 54-year-old male patient with autoimmune enteropathy who responded initially to a standard treatment with steroids, but was dependent on 30 mg prednisolone. Medical treatment was changed to tacrolimus after renal function deteriorated under treatment with cyclosporine A. Under this regimen, small bowel histology normalized and the clinical condition is stable after 2 years of introduction of tacrolimus. CONCLUSION: This constitutes the first report of effective treatment of adult autoimmune enteropathy with tacrolimus, a substance with a similar mode of action to cyclosporine, but with fewer side effects and improved bioavailability.

Administration, Oral↗
PubMed2003

Intestinal non-Hodgkin's lymphoma: a multicenter prospective clinical study from the German Study Group on Intestinal non-Hodgkin's Lymphoma.

PURPOSE: Intestinal non-Hodgkin's lymphomas are not well characterized. We therefore studied prospectively their clinical features and response to standardized therapy. PATIENTS AND METHODS: Fifty-six patients with primary intestinal lymphoma were included in a prospective, nonrandomized multicenter study. Lymphoma resection was recommended and staging was performed according to the Ann Arbor classification. Patients were scheduled to receive six cycles of cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP) chemotherapy, and at stages EIII to EIV, they received additional involved-field radiotherapy. Corticosteroids were used in patients who could not receive chemotherapy. RESULTS: Thirty-five patients had intestinal T-cell lymphoma (ITCL), 21 patients had intestinal B-cell lymphoma (IBCL; 18 diffuse large-cell lymphomas, two marginal-cell lymphomas, and one follicle-center lymphoma). Thirty-four patients at stages EI to EII (14 ITCL and 20 IBCL) and nine patients at stages EIII to EIV (all ITCL) received chemotherapy. No patient in stages EIII to EIV received radiotherapy, because death occurred in 12 of 14 patients. Two-year cumulative survival in patients with IBCL was 94% (95% CI, 82% to 100%) and higher than in patients with ITCL (28% [95% CI, 13% to 43%]; P <.0001), even when only stages EI to EII were considered (ITCL, 37.5% [95% CI, 16.5% to 58.5%]; P <.0001). IBCL patients compared with ITCL patients were at lower lymphoma stages (P <.01), had higher Karnofsky status (P <.005), had intestinal perforation less often (P <.05), required emergency operation less often (P <.05), received CHOP (P <.05) more often, and reached complete remission (P <.0005) more frequently. CONCLUSION: IBCL patients at stages EI and EII respond well to chemotherapy, but the prognosis and treatment of ITCL patients is unsatisfactory.

Adult↗
PubMed2003

Low toxic neoadjuvant cisplatin, 5-fluorouracil and folinic acid in locally advanced gastric cancer yields high R-0 resection rate.

PURPOSE: Neoadjuvant chemotherapy in locally advanced gastric cancer is effective, but is often associated with severe side effects, including fatal outcome. This study evaluates a combination of cisplatin, folinic acid and 5-fluorouracil (PLF) in terms of efficacy (R-0 resection rate) and toxicity. METHODS: Twenty-five patients with locally advanced gastric cancer who after extensive staging were deemed not suitable for curative resection underwent neoadjuvant chemotherapy. Three or four cycles of cisplatin (50 mg/m(2) days 1 and 15), folinic acid (200 mg/m(2) days 1, 8, 15 and 22), and 5-fluorouracil (2,000 mg/m(2 ) days 1, 8, 15 and 22) were administered. Cases with progressive disease were taken off the study. Two weeks after finishing chemotherapy resection was performed and all patients were enrolled in a structured follow-up. RESULTS: Of the patients, 22/25 finished chemotherapy and 20 of those underwent laparotomy. In 13/25 patients (52%) a R-0 resection and in three cases a R-1 resection were achieved. Four patients stayed irresectable. During 76 completed cycles of chemotherapy we observed five cases of WHO grade-III toxicity and no grade-IV toxicity. CONCLUSIONS: The presented PLF protocol yields R-0 resection rates comparable to protocols like EAP (etoposide, adriamycin, platinum), but with a better safety profile allowing administration in an outpatient setting. Our study supports PLF as a reference neoadjuvant treatment for gastric cancer even outside of clinical studies.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2003

Endoscopically inserted endoluminal receiver coil for high-resolution magnetic resonance imaging of the pancreas: Initial results in an animal model.

BACKGROUND: This study assessed the feasibility of high-resolution magnetic resonance imaging of the pancreas by means of an endoscopically inserted endoluminal magnetic resonance receiver coil. METHOD: A 0.032-inch diameter internal magnetic resonance imaging receiver coil was endoscopically inserted into the pancreatic duct in 4 pigs through the accessory channel of a standard duodenoscope to obtain high-resolution magnetic resonance images by using T1- and T2-weighted sequences. RESULTS: The pig anatomy precluded the usual transoral approach; however, transgastric access allowed endoscopic transpapillary insertion of a receiver coil into the pancreatic duct in all animals without the need for sphincterotomy. The small swine pancreas could then be visualized by magnetic resonance imaging with a 0.3 x 0.3-mm in-plane resolution. CONCLUSION: High-resolution pancreas magnetic resonance imaging is feasible by using an endoscopically inserted endoluminal receiver coil. The smaller stomach and larger pancreatic duct diameter in humans will facilitate clinical application of the imaging procedure.

Animals↗
PubMed2003

Congenital absence of the portal vein with splenomegaly and hypersplenism in a young woman.

Congenital absence of portal vein (CAPV) with a systemic shunt of enteric blood is a rare malformation. Twenty-seven cases have been reported to date; with the exception of 4 patients all cases had either liver anomalies or cardiac anomalies. CAPV is usually diagnosed before the age of 18 (25/27 cases). Here we present the case of a 33-year-old woman with CAPV without further anomalies. Beside suffering from circumscript scleroderma, splenomegaly and hypersplenism, the patient was otherwise healthy. Diagnosis was based on histological findings, angiography and CT scan. The liver biopsy showed portal tracts with inconspicuous arteries and bile ducts, but with severe loss of portal vein branches and minimal proliferation of bile ductules. In addition, the perivenular sinusoids were slightly dilated with focal parenchymal atrophy. Angiography showed a missing portal vein system and a missing splenic vein with drainage of the enteric blood through dilated perisplenic and perigastric collaterals to the azygos vein system. A CT scan revealed an empty liver hilus without portal vein. Here we discuss clinical aspects of this patient, show radiologic and histopathologic findings, and compare them to other cases in the literature.

Abnormalities, Multiple↗
PubMed2003

Pralnacasan (vertex pharmaceuticals).

Vertex is collaborating with Aventis Pharma AG (formerly Hoechst Marion Roussel Inc) in the development of pralnacasan, an interleukin (IL)-1b converting enzyme (ICE) inhibitor, for the potential treatment of inflammatory diseases [170247], [188293], [453094].

Anti-Inflammatory Agents, Non-Steroidal↗