COLORECTAL CARCINOGENESIS; ROLE OF OXIDATIVE STRESS AND ANTIOXIDANTS

One of the contributory causes of colon cancer is the negative effect of reactive oxygen species on DNA repair mechanism. Currently, there is a growing support for the concept that oxidative stress may be an important etiological factor for carcinogenesis. The purpose of this review is to elucidate the role of oxidative stress in promoting colorectal carcinogenesis and to highlight the potential protective role of antioxidants. Several studies have documentes the importance of antioxidants in countering oxidative stress and preventing colorectal carcinogenesis. However, there are conflicting data in the literature concerning its proper use in humans, since these studies did not yeld definitive results and were performed mostly in vitro on cell population, or in vivo in experimental animal models

Comparison of commercial DNA preparation kits for the detection of Brucellae in tissue using quantitative real-time PCR

<p>Abstract</p> <p>Background</p> <p>The detection of Brucellae in tissue specimens using PCR assays is difficult because the amount of bacteria is usually low. Therefore, optimised DNA extraction methods are critical. The aim of this study was to assess the performance of commercial kits for the extraction of <it>Brucella </it>DNA.</p> <p>Methods</p> <p>Five kits were evaluated using clinical specimens: QIAamp™ DNA Mini Kit (QIAGEN), peqGold™ Tissue DNA Mini Kit (PeqLab), UltraClean™ Tissue and Cells DNA Isolation Kit (MoBio), DNA Isolation Kit for Cells and Tissues (Roche), and NucleoSpin™ Tissue (Macherey-Nagel). DNA yield was determined using a quantitative real-time PCR assay targeting IS<it>711 </it>that included an internal amplification control.</p> <p>Results</p> <p>Kits of QIAGEN and Roche provided the highest amount of DNA, Macherey-Nagel and Peqlab products were intermediate whereas MoBio yielded the lowest amount of DNA. Differences were significant (p < 0.05) and of diagnostic relevance. Sample volume, elution volume, and processing time were also compared.</p> <p>Conclusions</p> <p>We observed differences in DNA yield as high as two orders of magnitude for some samples between the best and the worst DNA extraction kits and inhibition was observed occasionally. This indicates that DNA purification may be more relevant than expected when the amount of DNA in tissue is very low.</p

MODULATION OF MUCIN

The iinate and acquired immune systems are both implicarted in the etiology of Inflammatory Bowel Disease (IBD) in addition to the genetic predisposition, the environmental factors and the intestinal flora covering the mucosa. A defect in the mucous covering will lead to an invasion of pathogens and stimulation of the immuune response with aberrations of mucin 2, the major mucin of the mucous layer. Aim: this study aims to assess the modulation of colonic MUC 2 and MUC 3 in a arat model of IBD induced by a combination of iodoacetamide and enteropatogenic E. Coli. Methods: 78 sprague-Dawley female rats were divided into 4 groups. Each group was subjeceted, on a basis, to a rectal injection of 1% methylcellulose (MC), the veicle, or saturated enteropathogenic E. coli bacterial suspension, or 3% iodoacetamide (IA) in 1% MC, or 3% IA followed by E. Coli infection 48 hours later. Biopsies of the colon were obtained for light microscopy and indirect immunofluorescence using a monoclonal primary antibody MUC 2 and MUC 3. Colonic mucosal scrapings were also use dfor RNA extraction and running for real-time PCR usong MUC 2 and MUC 3 primers. Results: Under light microscopy, the histological sections revealed severe colonic tissue damage in the IA and IA + B groups throughout the experiment. Conclusions: this induuced IBD model succeeded in the arousal and maintanence of IBD for a 2-months period. this inflammation lead to a clear mucosal tissue damage and disruption of the mucosal barrier, togheter with a decreased expression of MUC 2, both on the protein and the RNA levels, whereas MUC 3 expression was not significantly altered

A NOVEL THERAPEUTIC APPROACH TO COLORECTAL CANCER IN DIABETES: ROLE OF METFORMIN AND RAPAMYCIN

The link between colorectal cancer (CRC), diabetes mellitus (DM) and inflammation is well established, and polyterapy, including rapamycin, has been adopted. This study is a novel approach that aimed at assessing the effect of a combination therapy of metformin and rapamycin on the control or prevention of CRC in diabetic animals, in presence or absence of probiotics. Fifty NOD/SCIDs male mice developed xenograft by inoculating HCT16 cells. They were equally divided into diabetics (induced by Streptozocin) and non-diabetics. Metformin was given in drinking water, whereas rapamycin was administered via intra-peritoneal injections. Probiotics were added to the double therapy two weeks before the sacrifice. Assessment was performed by clinical observation, histological analysis. Reactive oxigen species (ROS) activities and molecular analysis of Interleukin 3 and 6. Tumor Necrosis Factor alpha. AMP-activated protein Kinase and the mammalian target of rapamycin. decreases in the level of tumorigenesis resulted, to various extents, with the different treatment regimens.The combination of rapamycin and metformin had no significant result, however, after adding probiotics to the combination, there was a marked delay in tumor formation and reduction of its siza, suppression of ROS and decrease in inflammatory cytokines as well as an inhibition of phospohorylated mTOR. Existing evidence clearly supports the use of rapamycin and metformin especially in the presence of probiotics. It also highlighted the possible mechanism of action of the 2 drugs through AMPK and mTOR signaling pathways and offered preliminary data on the significant role of probiotics in the combination. Further investigation to clarify is needed

COLORECTAL CANCER AND INFLAMMATORY BOWEL DISEASES: EFFECTS ON DIET AND ANTIOXIDANTS

It is well established that oxidative stress is common in inflammatory bowel diseases (IBDs). Accordingly, antioxidants are recommended for treatment. The aim of this is to compare the effects of antioxidants contained in the various types of tea on symptoms and evolution of IBD and colorectal cancer (CRC). Analysis of the literature revealed that the theaflavin-3, 30-digitale (TFDG) contained in black tea, and epigallocatechin-3-0-gallate (EGCG) contained in green tea have protective effects against oxidative stress. Moreover, these substances are involved in many biochemical processes responsible for inflammation and proliferation of cancer cells. It is documented that both TFDG and EGCG are able to reduce inflammatory phenomena and sympotms associated with IBD, as well as to reduce the proliferation of CRC cells. Most studies are performed in vitro or in experimental animal models. It is, therefore, advisable to formulate studies that could be carried out on humans or human samples, in order to develop the appropriate therapeutic strategies

NUTRACEUTICALS IMPROVE EXPERIMENTAL COLITIS: PLACE OF CATECHINS IN THE 2,4,6-TRINITROBENZENE SULFONIC ACID MODEL RATS

Background: Nutraceuticals provide added health benefits for inflammatory bowel disese (IBD) and Epigallocatechin-3-galate (EGCG), a green tea catechin, has been shown to possess such anti-inflammatory and anti-oxidant effects. Aim: To evaluate the molecular modulation of Reactive Oxygen Species (ROS), Tumor Necrosis Factor-alpha (TNF_alpha), nuclear factor Kappa Beta (NF-Kbeta), Interleukin 6 (IL-6) by EGCG on experimental colitis. Matherial and Methods: Thirthy five male sprague-dawley rats were randomly divided into 4 groups: Normal control group (n=5), EGCG group (n=9), TNBS group (n=9), and TNBS + EGCG group (n=12). For both TNBS and EGCG treated groups, 1 mg/Kg EGCG was administered daily by intraperitoneal injection, starting one week before the induction. at days 3, 10, and 17, rats were sacrificed and the descending colon was collected. The mRNA expressions of IL-6, TNF-alpha and NF-KB were measured by the polymerase chain reaction. In addition, the oxidative stress wasstudied by determination of ROS expression using dihydroethinidine (DHE) staining. results: The results showed that EGCG caused a significant decrease in the mRNA expression of pro-inflammatory cytokines IL-6, TNF-alpha and NF-KB compared to respective non-treated groups. In addition, ROS expression was reduced. Conclusions: These data provide evidence that EGCG is beneficial in TNBS-induced colitis; it exerts an antioxidant activity via decreasing ROS, and an anti-inflammatory effect via ameliorating histological findings and reducing IL-6, TNF-alpha and NF-KB