Mesothelioma

Mesothelioma is a malignant tumour that develops from the mesothelium tissue (a membrane that covers the internal organs present in the body). It occurs very rarely and is more a great deal bringd by inhaling asbestos dust. The incidence of the disease is slowly on the rise. In the US, about 2000 new cases are report every year. About 70 to 80% of all cases with mesothelioma report exposure to asbestos (NCI, 2002). Mesothelioma can develop in various sites of the body including the pleura (membranes that covers the lungs), peritoneum (membrane that covers the abdominal cavity), tunica vaginalis testis (membrane that covers the male internal reproductive organs) and tunica serous membrane uteri (membrane that covers the female internal reproductive organs) (NCI, 2002).It is made up of one layer of flat or three-dimensional cells that surround a peculiar(prenominal) organ or an organ set belonging to a particular group (Weitz & Luxenberg, 2006). In between these membranes a fluid is present that permits some amount of movement during physiologic functioning. When the asbestos is inhaled, it renders deposited into parenchyma of the lungs from where it enters the immediate membrane that covers the lungs. It whitethorn be carried soon to the other membrane of the lung. The tumor usually comes as discrete plaques known as malignant mesothelial plaques (Weitz & Luxenberg, 2006).These discrete masses soon combine to form a large sheet like lesion that spreads. The exact process by which mesothelioma occurs is not understood clearly, however, it seems that chronic exacerbation of the membrane plays a very important role (Weitz & Luxenberg, 2006). The chromosomes present in the cell are malformed (Tan, 2007). One of the most frequent changes in the malignant cell was the loss of a copy of Chromosome 22.The chromosomal picture of the cell seems to be very complex (complex karyotype) and is rearranged (Tan, 2007). Sometimes, the chromosome arms of 1p, 3p, 9p and 6q may also get structurally rearranged. This may be brought about by close contact between the chromosomes or the structural proteins with the asbestos particles (Weitz & Luxenberg, 2006).The asbestos may get deposited in the peritoneum either through the lymphatic system or the due ingestion of the sputum from the lungs (Weitz & Luxenberg, 2006). The long thin fibers of asbestos are more dangerous than the feathery fibers as they more easily cause cancer. Once the fibers get deposited in the pleura, the cancer development process actually begins. In experimental rats, it has been ascertained that when the pleura or the peritoneum are invaded by the asbestos particles, macrophages and the other cells of the bodys defense mechanism accumulate (Weitz & Luxenberg, 2006).As the disease progresses, the macrophages and immune cells continue to invade the lesion. Slowly the cells get transformed into malignancy. Studies have demonstrated that the asbestos particles may directly (through physical interaction) and indirectly (through accumulation of macrophages) bring about malignant transformation of the epithelium cells. Indirectly, the macrophages begin to function supernormally. They phagocyte the asbestos particles and release higher amounts of hydroxyl radicals.They may stimulate the cancer process by touch on the DNA present in the cell. Several other substances are released from the macrophages such as mitogens, harvest-festival factors, etc, which may bring about chronic irritation. They also alter entry of certain substances into the cell (by affecting the membrane) and reducing the effect of antioxidant action within the cells. Asbestos is also known to suppress the action of the bodys defense mechanism by overcoming the action of the lymphocytes (Weitz & Luxenberg, 2006).Several structural and functional features have been observed in the cells affected with mesothelioma (which have asbestos particles within the cells) 1.the suppressor genes against ca ncers present in the cells may get inactivated when the asbestos fibers enters the cells2.other cancer-stimulating agents may get activated and affect the cell3. the DNA of the cell gets altered due to the incorporation of a unknown DNA which encourages cancer formation4. the DNA repair enzymes may get stimulated and frequently pass on in a faulty method of repair5.the cell terminal processes may become abnormal resulting in immortality6.the DNA sequence may be added at the ends of the cell which makes the cells immortal and results in abnormal functioning (Weitz & Luxenberg, 2006)ReferencesNCI. Mesothelioma Questions and Answers. 2002. NCI. 5 Apr. 2007 http//www.cancer.gov/cancertopics/factsheet/Sites-Types/mesotheliomaTan W.W. Mesothelioma. 2007. E-Medicine. 5 Apr. 2007 http//www.emedicine.com/med/topic1457.htmWeitz & Luxenberg. The Pathophysiology of Mesothelioma. 2006. Weitz & Luxenberg Inc. 5 Apr. 2007 http//www.weitzlux.com/mesothelioma/Pathophysiology_403723.html