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When activated, RTKs in turn activate the Ras, Raf, MEK, MAPK, MKK, ERK, Fos, JNKs, and Jun pathway, which can lead to the induction of ARF via gene upregulation. ARF in turn suppresses mdm2, a suppressor of p53 activity. The resulting increase in p53 activity can induce Bax, Mt, and thus apoptosis.
4. Adenomatous familial polyposis is caused by a truncated APC protein, which results from inherited mutations in the APC gene (Segditsas and Tomlinson, 2006). However, the activity of the wild-type or normal APC allele is usually sufficient to maintain tumor suppressor activity. For this reason, and because the wild-type allele is often found to have acquired somatic mutations, it is assumed that both alleles must be mutated before tumors can form. The vast majority of mutations found in colorectal tumors have retained 0 to 3 20-amino acid repeats, suggesting APC proteins that retain some ?-catenin binding activity result most often in tumor formation. The following describes the steps believed to occur from inheriting a mutated APC allele to the formation of cancer:
a. An APC allele with a mutation that truncates the expressed protein after the second 20-amino acid repeat domain is inherited.
b. The other normal APC...
The loss of heterozygosity leads to decreased tumor suppressor activity, because the APC proteins are limited in their ability to bind and degrade ? -- catenin.
d. In the presence of Wnt signaling, the translocation of increased levels of ? -- catenin to the nucleus results in proliferation and transformation. The 'just right' hypothesis suggests that limited APC tumor suppressor activity conferred by the inherited and somatic mutations allows Wnt signaling to be just right for tumor development. In support of this argument, complete loss of APC is not a common mutation found in colorectal tumors.
References
Libby, Peter, Ridker, Paul M., and Hansson, Goran K. (2011). Progress and challenges in translating the biology of atherosclerosis. Nature, 473, 317-325.
Segditsas, S. And Tomlinson, I. (2006). Colorectal cancer and genetic alterations in the Wnt pathway. Oncogene, 25, 7531-7537.
Minde, David P., Anvarian, Zeinab, Rudiger, Stefan G.D., and Maurice, Madelon M. (2011). Messing up disorder: How do missense mutations in the tumor suppressor protein APC lead to cancer? Molecular Cancer, 10, 1-9.
Aging and Retirement Reference Brochure Baernholdt, M., Hinton, I., Yan, G., Rose, K., & Mattos, M. (2012). Factors associated with quality of life in older adults in the United States. Quality of Life Research, 21(3), 527-534. doi: 10.2307/41445078 Black, B.S., Johnston, D., Morrison, A., Rabins, P.V., Lyketsos, C.G., & Samus, Q.M. (2012). Quality of life of community-residing persons with dementia based on self-rated and caregiver-rated measures. Quality of Life Research, 21(8), 1379-1389.
The gradual decrease in income, eventual dependency on other people and the government for financial resource, lack of activities to do, and the onset of physical and/or physical limitations as a result of aging are known causes of frustration, stress, and even depression among elderly people who have retired (Blekesaune and Solem, 2005, p. 80). In the case of Mrs. a, she has not experienced these negative feelings or
Lubben, James E. And Damron-Rodriguez, JoAnn. 2003. " An international approach to community health care for older adults." Family and Community Health. October-December. available from Proquest Database. In this article, Lubben and Damron-Rodriguez propose a model for community-based primary healthcare that could be more responsive to the needs of the growing elderly population around the globe. Lubben and Damron-Rodriguez base their study by analyzing the results and ramifications of the
Physiological Changes Associated With Aging Aging is the complex and inevitable process of tissue and organ system degeneration. Though largely influenced by genetics, aging is also dependent upon a number of environmental factors including exercise, diet, childhood personality, and exposure to ionizing radiation, pollutants, or microorganisms. The physiological changes that occur as an individual's age advances can be grouped into three, with the first category encompassing changes in such homeostatic mechanisms
Cellular Function and Aging Tumor Suppression Protein 53 and Effects on Cellular Function and Aging The concept of aging has many intrinsic and extrinsic factors that act as markers on an individual organism. Ignoring mortality associated with external environmental factors, very few organisms can be said to have cellular immortality with no decrease in cellular function or repeat division in normal diploid cells. Cellular senescence is a normal process that halts
Efforts to Achieve Healthy Aging Ping-Chung Leung Institute of Chinese Medicine, The Chinese University of Hong Kong, HKSAR. Abstract: Longevity is a blessing as long as good health is not lost. However, the tendency to have a decline on normal physiological activities is inevitable because of the natural processes of degeneration at all levels: molecular, cellular and organic. Hence, the elderly people frequently suffer from cardiovascular problems and skeletal deteriorations that gradually develop