Somatostatin-induced gastric protection against ethanol: involvement of nitric oxide and effects on gastric mucosal blood flow

BACKGROUND--AIMS:The mechanisms of somatostatin-mediated gastroprotection are not fully understood. Aims of this study were to determine in the rat the role of nitric oxide (NO) in somatostatin-induced effects on gastric mucosal protection and blood flow (GMBF) in the absence and in the presence of intraluminal ethanol. METHODS: Ethanol (70% v/v)-induced gastric mucosal injury after orogastric dosing was quantitated at 30 min and GMBF determined in an ex vivo gastric chamber preparation. RESULTS: Somatostatin (4 microg/kg; i.p.) protection against ethanol-induced ulceration was prevented by the NO inhibitor L-NNA and restored by L-arginine, but not D-arginine. Somatostatin (1-8 microg/kg; i.p.) did not effect basal GMBF. The gastroprotective dose of somatostatin (4 microg/kg; i.p.) prevented the decrease in GMBF caused by ethanol. L-NNA reversed this vascular effect of somatostatin. CONCLUSION: Somatostatin-induced gastroprotection and restoration of GMBF during ethanol exposure involve mechanisms which are dependent on NO generation.     

Molecular cloning,structural analysis,and expression of a human IRLB,MYC promoter-binding protein: new DENN domain-containing protein family emerges

IRLB was originally identified as a partial cDNA clone, encoding a 191-aa protein binding the interferon-stimulated response element (ISRE) in the P2 promoter of human MYC. Here, we cloned the full-size IRLB using different bioinformatics tools and an RT-PCR approach. The full-size gene encompasses 131 kb within chromosome 15q22 and consists of 32 exons. IRLB is transcribed as a 6.6-kb mRNA encoding a protein of 1865 aa. IRLB is ubiquitously expressed and its expression is regulated in a growth- and cell cycle-dependent manner. In addition to the ISRE-binding domain IRLB contains a tripartite DENN domain, a nuclear localization signal, two PPRs, and a calmodulin-binding domain. The presence of DENN domains predicts possible interactions of IRLB with GTPases from the Rab family or regulation of growth-induced MAPKs. Strongly homologous proteins were identified in all available vertebrate genomes as well as in Caenorhabditis elegans and Drosophila melanogaster. In human and mouse a family of IRLB proteins exists, consisting of at least three members.     

Role of extracellular DNA oxidative modification in radiation induced bystander effects in human endotheliocytes

The development of the bystander effect induced by low doses of irradiation in human umbilical vein endothelial cells (HUVECs) depends on extracellular DNA (ecDNA) signaling pathway. We found that the changes in the levels of ROS and NO production by human endothelial cells are components of the radiation induced bystander effect that can be registered at a low dose. We exposed HUVECs to X-ray radiation and studied effects of ecDNA(R) isolated from the culture media conditioned by the short-term incubation of irradiated cells on intact HUVECs. Effects of ecDNA(R) produced by irradiated cells on ROS and NO production in non-irradiated HUVECs are similar to bystander effect. These effects at least partially depend on TLR9 signaling. We compared the production of the nitric oxide and the ROS in human endothelial cells that were (1) irradiated at a low dose; (2) exposed to the ecDNA(R) extracted from the media conditioned by irradiated cells; and (3) exposed to human DNA oxidized in vitro. We found that the cellular responses to all three stimuli described above are essentially similar. We conclude that irradiation-related oxidation of the ecDNA is an important component of the ecDNA-mediated bystander effect.     

PPARgamma activation by thiazolidinediones (TZDs) may modulate breast carcinoma outcome: the importance of interplay with TGFbeta signalling

The thiazolidinediones (TZDs) are a class of synthetic antidiabetic drugs exerting its action primarily upon activation of the peroxisome proliferator-activated receptor-gamma (PPARgamma). Given the widespread incidence of diabetes type II and lifelong exposure of these patients to TZDs, there is a possibility that chronic treatment with TZD modifies clinical phenotypes of other common human diseases, for example breast carcinoma. There is evidence that TZDs act as breast carcinoma suppression agents, at least in the in vitro and animal models. Stimulation of the PPARgamma by TZDs interferes with oestrogen receptor signalling, STAT5B and NF-kappaB signalling cascades. On the other hand, TZDs repress TGFbeta signalling, a well-known suppressor of the initial stages of breast carcinoma development. Another layer of complexity arises at the later stages of tumour development, when TGFbeta acts as a tumour promoter: its overexpression is associated with poor prognosis, higher degree of tumour vascularization and metastasis. Longitudinal studies of breast carcinoma development in chronic TZD users are needed. In this review, we dissect possible interplays between chronic exposure of breast tis-sue to TZDs and TGFbeta signalling and predict influence of TZD exposure on cancer-related clinical outcome.     

Knowledge-Based Identification of Soluble Biomarkers: Hepatic Fibrosis in NAFLD as an Example

The discovery of biomarkers is often performed using high-throughput proteomics-based platforms and is limited to the molecules recognized by a given set of purified and validated antigens or antibodies. Knowledge-based, or systems biology, approaches that involve the analysis of integrated data, predominantly molecular pathways and networks may infer quantitative changes in the levels of biomolecules not included by the given assay from the levels of the analytes profiled. In this study we attempted to use a knowledge-based approach to predict biomarkers reflecting the changes in underlying protein phosphorylation events using Nonalcoholic Fatty Liver Disease (NAFLD) as a model. Two soluble biomarkers, CCL-2 and FasL, were inferred in silico as relevant to NAFLD pathogenesis. Predictive performance of these biomarkers was studied using serum samples collected from patients with histologically proven NAFLD. Serum levels of both molecules, in combination with clinical and demographic data, were predictive of hepatic fibrosis in a cohort of NAFLD patients. Our study suggests that (1) NASH-specific disruption of the kinase-driven signaling cascades in visceral adipose tissue lead to detectable changes in the levels of soluble molecules released into the bloodstream, and (2) biomarkers discovered in silico could contribute to predictive models for non-malignant chronic diseases.