is critical to our ability to repair, restore and protect hearing
The tumour microenvironment has been proposed to contribute to the increased genetic instability seen in cancer cells. Several studies have lent support to this notion, including a study that demonstrated a higher rate of genomic instability of mouse cells when grown in vivo as subcutaneous tumour implants in syngeneic mice, as measured using an EGFP reporter gene and a genomic minisatellite locus (Li et al., 2001). More specifically, hypoxia has been singled out as a major microenvironmental factor. Hypoxia, which appears to occur transiently within the tumour microenvironment, has been shown to lead to cycles of hypoxia and reoxygenation (Bindra and Glazer, 2005). This is thought to lead to DNA damage as a result of reactive oxygen species (ROS) and the enzyme superoxide dismutase. In addition to ROS leading to the formation of 8-oxoG, and accumulating evidence suggest a role for oxygen and ROS in causing single and (Bindra and Glazer, 2005). In addition to its ability to cause aberrations in DNA, these cycles of hypoxia and reoxygenation have been shown to affect DNA synthesis, by both interrupting this process and by leading to over-replication after reoxygenation (Bindra and Glazer, 2005; Cuvier et al., 1997; Young. and Hill, 1990; Young et al., 1990). Other studies have found that it is hypoxia induced gene amplification of p-Glycoprotein that is responsible for the observed resistance to adriamycin and doxorubicin (Luk et al., 1990; Rice et al., 1987), indicating that gene amplification may also be caused by hypoxia. Furthermore, emerging evidence suggests that hypoxia can influence the integrity of the genome by impacting upon DNA repair pathways. As described above, MLH1 is one of the key genes involved in mismatch repair. It was shown that hypoxia downregulates the expression of the MLH1 gene at the transcriptional level and this was thought to occur via chromatin remodeling, as treatment with an histone deacteylase inhibitor prevented the aforementioned decrease (Mihaylova et al., 2003). It has also been demonstrated that hypoxia enriches for MMR deficient cells (Hardman et al., 2001). Thus, DNA damage, defective DNA synthesis, gene amplification and the deregulation of DNA repair pathways all appear to be mechanisms by which hypoxia contributes to genetic instability. Little is still known about other microenvironmental factors that may lead to instability. However, it has been suggested that the tumour microenvironment may represent in mammalian cells a conserved evolutionary mechanism that increases the rate of mutation in response to cellular stresses, which preferentially gives cancer cells a survival advantage (Bindra and Glazer, 2005).
I will call it the etheric hypothesis of aging
Hypothesis : the new marriage definition is unworkable (whether in prose or in rhyme). Genetics, Canadian Marriage, and the Law (In prose) The importance of genetics, particularly at the molecular level, has almost become a given in the work of virtually all of our laboratories. At the most fundamental level DNA is sequenced, DNA is […]
Thus, this sort of approach isn't recommended unless you really need the highcapacity - testing of other microwave ovens or ion laser power supplies, forexample!
Civil engineering and infrastructure repair in New …
What is a scientist? If you ask a seven year old to draw a scientist, he will draw a man in a lab coat holding a frothing beaker with white hair standing on end. This hairstyle is otherwise known as the ‘stick your finger in the light socket look’ and my grade 10 biology teacher […]
Doctors restore consciousness in man who ..
It is with great pleasure that we introduce the inaugural issue of Hypothesis, a peer-reviewed journal that focuses on the sharing and discussion of novel, interdisciplinary research and ideas within the University of Toronto community. The present time is an extremely exciting era for science. The availability of numerous genome sequences and our growing ability to gather […]
Troubleshooting and Repair of Consumer Electronic …
There is substantial evolutionary selection pressure acting on all multicellular species to prevent the formation and uncontrolled growth of tumours prior to reproductive age. Interestingly, the quantum nature of tumourigenesis (specifically the monoclonal origin of most tumours) implies differing consequences for species with large differences in body size and life-span. Introduction Multicellular organisms are communities […]
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Whilst mustering the courage to begin my reclassification proposal in the winter of 2003 I came upon a reference to LaTeX, a typesetting and document formatting method popular among scientists and mathematicians. LaTeX was described as a highly robust way to prepare scientific articles, reports, and other documents. My interest was piqued, especially considering my […]