13.cancer.can.anything.cause

13.cancer.can.anything.cause - Cancer- Can Anything Cause...

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Unformatted text preview: Cancer- Can Anything Cause It?? Introduction Chronic Toxicity Mutagenesis and DNA Carcinogenesis – What is Cancer? Genotoxic and Epigenetic Carcinogens Summary and Conclusions History of Cancer in Humans Cancer – a disease characterized by abnormal cells that grow and divide uncontrollably, ultimately invading and destroying adjacent tissues. Causes of Human Cancer Deaths Cancer – A Disease of Genetics A C G T = Adenine = Cytosine = Guanine = Thymine DNA – Codes for all Proteins in the Body Carcinogenic Process Some Important Definitions Mutagen – a chemical that directly reacts with DNA to cause a change in its function. Carcinogen – a chemical that causes cancer by any means. Genotoxic carcinogen – a chemical that causes cancer by directly reacting with DNA to cause a change in its function. Epigenetic carcinogen – a chemical that causes cancer by non-genetic means (it does not directly interact with DNA). Is This True? Not all mutagens are carcinogens. Yes – many mutagens target DNA that does not control cell growth and division. Mutation is a part of the natural selection process. Not all carcinogens are mutagens. Yes – many carcinogens serve to cause cancer by non-genetic means, such as by suppressing the immune system or increasing cell division rate, reducing DNA repair efficiency. Benzo[a]pyrene and Lung Cancer Repair of DNA Development of cancer following mutagenesis is a very rare event. Cells efficiently recognize and either repair or replace damaged DNA. The repair efficiency is well above 99%, but declines slightly with age. Impaired repair mechanisms can lead to development of cancers at an early age. Types of General Tumors Benign tumors – tumors that contain cells that are similar to normal cells. The cells do not invade and destroy adjacent tissues. Malignant tumors – tumors that are different from normal cells. The cells generally invade and destroy adjacent tissues. Metastasis – a process by which cells break free of their origin tumor and circulate to other parts of the body. General prognosis for treatment deteriorates. Human Lung and Skin Tumors Flatfish and Tumors in Puget Sound Green Sea Turtles and Fibropapillomas Some Types of Cancers Carcinoma – cancer that arises from epithelial cells (covering body or tissue surfaces). Sarcoma – cancer that arises from supporting or connective tissues (such as muscle). Melanoma – cancer that arises from the pigmented cells of the skin (containing the pigment melanin). Lymphoma – cancer that arises from the cells of the lymphatic system. International Agency for Research on Cancer A part of the WHO, it classifies carcinogens based upon available scientific information. Classifications are regularly updated. Classification is based on the weight of scientific evidence, with human evidence weighted most heavily. Currently some 39 chemicals are listed as known human carcinogens (class 1). Human Carcinogen Classification ome of the IARC Class 1 Human Carcinogens Aflatoxins Estrogens Class 2A and 2B Human Carcinogens PCBs (2A) Dioxins and Dibenzofurans (2B) Victor Yuschenko in Ukraine, 2004 (chloracne). Class 3 and 4 Human Carcinogens Diazepam (Valium) Caprolactam (4) Conclusions Cancer is a natural disease of genetics. There are genotoxic and epigenetic carcinogens. Cancer usually takes years to develop. There are many environmental causes of cancer. Not all chemicals cause cancer – many do not! ...
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This note was uploaded on 02/01/2010 for the course ETX etx10 taught by Professor Rontjeerderma during the Fall '09 term at UC Davis.

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13.cancer.can.anything.cause - Cancer- Can Anything Cause...

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