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

Recruited Cells Can Become Transformed and Overtake PDGF-Induced Murine Gliomas In Vivo during Tumor Progression

Gliomas are thought to form by clonal expansion from a single cell-of-origin, and progression-associated mutations to occur in its progeny cells. Glioma progression is associated with elevated growth factor signaling and loss of function of tumor suppressors Ink4a, Arf and Pten. Yet, gliomas are cellularly heterogeneous; they recruit and trap normal cells during infiltration.We performed lineage tracing in a retrovirally mediated, molecularly and histologically accurate mouse model of hPDGFb-driven gliomagenesis. We were able to distinguish cells in the tumor that were derived from the cell-of-origin from those that were not. Phenotypic, tumorigenic and expression analyses were performed on both populations of these cells. Here we show that during progression of hPDGFb-induced murine gliomas, tumor suppressor loss can expand the recruited cell population not derived from the cell-of-origin within glioma microenvironment to dominate regions of the tumor, with essentially no contribution from the progeny of glioma cell-of-origin. Moreover, the recruited cells can give rise to gliomas upon transplantation and passaging, acquire polysomal expression profiles and genetic aberrations typically present in glioma cells rather than normal progenitors, aid progeny cells in glioma initiation upon transplantation, and become independent of PDGFR signaling.These results indicate that non-cell-of-origin derived cells within glioma environment in the mouse can be corrupted to become bona fide tumor, and deviate from the generally established view of gliomagenesis

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

Stand structure and regeneration of Cedrus libani (A. Rich) in Tannourine Cedar Forest Reserve (Lebanon) affected by cedar web-spinning sawfly (Cephalcia tannourinensis, Hymenoptera: Pamphiliidae)

The analysis of forest structure is a useful tool to understand stand biodiversity characterizing forest ecosystems, and could help in suggesting appropriate management plans. Cedar forests in Lebanon are remnant patches that survived past human activities but are still threatened by other different anthropogenic and natural disturbances. Among these threats, the cedar web-spinning sawfly (Cephalcia tannourinensis) discovered in Tannourine Cedar Forest Nature Reserve in 1997, which is able to cause the death of trees. The aim of this study is to investigate the impact of this pest on the stand structure and regeneration of Cedrus libani in Tannourine Cedar Forest Nature Reserve located in North Lebanon. The dependence of stand structural attributes (diameter at breast height, total height and basal area) on the presence of infestation by the cedar web-spinning sawfly was identified using the Student’s t-test. The Ripley’s K(d) function was used to analyse the spatial pattern of cedar stands. In addition, the diameter, the vertical structure and the crown projection were characterized using the Weibull function and graphic representations. The results showed that stand structure and regeneration are significantly different between infested and non-infested stands. The cedar of Lebanon remains as the dominant species, with abundant young individuals and a good regeneration status (c = 1.0). The analysis of the spatial pattern showed a positive spatial relationship between mature Lebanese cedar trees as well as between mature and juvenile cedars, with a bigger aggregation in infested plots (6 to 10 meters) than in non-infested quadrates (2 to 7 meters), reflecting the impact of the cedar web-spinning sawfly on the stand structure and regeneration of Cedrus libani stands

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

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