7. Viruses and Cancer

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7. Viruses and Cancer
2011-08-11 05:50:58
PH162A midterm3

public health microbiology midterm 3 lecture 7
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  1. Cancer
    uncontrolled growth of abnormal cells in the body
  2. cell maturation sequence
    • starts with stem cell, ends with terminally differentiated cell
    • at each division one daughter cell remains the same and the other becomes more mature
    • usually change morphology as they mature
    • at end, cells do not divide but die after a certain amount of time (terminal differentiation)
  3. cell maturation sequence and cancer
    • maturation sequence allows for proliferation
    • terminal differentiation keeps the cell number constant
    • cells transformed into cancer cells only at early steps of maturation in immature cells that are actively dividing - DNA synthesis is required to fix change in the genome and pass it on
  4. tumor
    any bulge or swelling, usually due to cellular growth
  5. neoplasm
    new abnormal cellular growth beyond the normal amount
  6. benign
    having some abnormal growth but not spreading to distant sites via lymph or blood
  7. malignant
    having abnormal growth and potential for spreading distant sites via lymph or blood
  8. metastasize
    to spread to distant sites via blood or lymph
  9. 3 types of cancer depending on tissues involved
    • carcinoma - involves epithelial cells
    • sarcoma - involves connective tissue
    • leukemia and lymphoma - involve blood cells
  10. carcinogens categories
    • chemical carcinogens
    • radiation
    • viruses
  11. properties of oncogenic viruses
    • must be lysogenic or latent, not lytic, so it can persist in the infected cell and cause the required genetic changes
    • must be able to alter the cell's growth pattern such that normal terminal differentiation is blocked and the cell keeps on dividing
  12. Cervical Cancer etiology
    • human papilloma virus
    • dsDNA
    • Types:
    • cervical cancer - 16,18
    • body warts - 1-4
    • genital warts - 6,11
  13. Cervical Cancer transmission
    sexual contact
  14. Cervical Cancer pathogenesis
    • infects epithelial cells on cervix
    • HPV has 2 transforming genes E6 and E7 which inactivate a tumor suppressor protein
  15. Cervical Cancer clinical
    • most women are subclinical
    • fewer women develop cervical dysplasia (precancerous)
    • cervical carcinoma is least frequent
  16. Cervical Cancer diagnosis
    • appearance of the cervix
    • papanicolaou smear
  17. Cervical Cancer treatment
    • cervical dysplasia (precancerous areas) - removed by cone biopsy
    • cervical cancer - hysterectomy
  18. Cervical Cancer prevention
    • annual pap smear
    • STI prevention
    • two vaccines now on market
  19. Bukitt's Lymphoma and Nasopharyngeal carcinoma etiology
    • epstein-barr virus
    • dsDNA virus
  20. Bukitt's Lymphoma and Nasopharyngeal carcinoma transmission
    close oral contact
  21. Bukitt's Lymphoma and Nasopharyngeal carcinoma clinical manifestations
    • most people are asymptomatic but produce antibodies
    • some people develop infectious mononucleosis
    • most serious disease is cancer
  22. Bukitt's Lymphoma
    • consists of large tumors made up of malignant lymphocytes, usually originating in the jaw or eye
    • found primarily in African children
  23. Nasopharyngeal carcinoma
    • arise in lymphoid tissue of the nasopharynx and metastasize early to lymph nodes in the neck
    • occurs primarily in Asians
  24. Bukitt's Lymphoma and Nasopharyngeal carcinoma cofactors
    Bukitt's Lymphoma - malaria, mirrors distribution, depresses the CMI response

    Nasopharyngeal carcinoma - genetic predisposition, environmental carcinogens
  25. Bukitt's Lymphoma and Nasopharyngeal carcinoma diagnosis
    • biopsy
    • for NPC, detection of elevated IgA to EBV
  26. Bukitt's Lymphoma and Nasopharyngeal carcinoma treatment
    • chemotherapy
    • radiotherapy
    • surgery
  27. Bukitt's Lymphoma and Nasopharyngeal carcinoma prevention
    • very difficult
    • possibly remove cofactor
  28. Primary Hepatocellular Carcinoma etiology
    • Hepatitis B Virus
    • partially dsDNA
  29. Primary Hepatocellular Carcinoma incidence
    areas with highest incidence are areas with highest prevalence of chronic carriers of HBV
  30. Primary Hepatocellular Carcinoma transmission
    • contaminated blood products
    • sexual contact
    • vertical transmission
  31. Primary Hepatocellular Carcinoma pathogenesis
    • virus infects hepatocytes
    • in some cells, establishes long-term infection
    • transforming gene of virus encodes for a protein that inhibits DNA repair - accumulation of mutations in cell may lead to cancerous mutations
  32. Primary Hepatocellular Carcinoma clinical
    • most infections asymptomatic
    • some infected people develop hepatitis
    • fewer people develop HPC
  33. Primary Hepatocellular Carcinoma diagnosis
    • detection of alpha-fetoprotein
    • imaging techniques
  34. Primary Hepatocellular Carcinoma treatment
    various types of surgery, liver transplantation
  35. Primary Hepatocellular Carcinoma prevention
    • vaccine against HBV
    • break mother to child cycle
    • identify chronic carriers and monitor for alpha-fetoprotein after 40
    • chronic carriers should also avoid alcohol
  36. Adult T cell Leukemia etiology
    • human T cell leukemia virus
    • RNA retrovirus
  37. Adult T cell Leukemia transmission
    blood-borne route and body fluids
  38. Adult T cell Leukemia pathogenesis
    • virus infects T lymphocytes - CD4 serves as receptor
    • HTLV transforming protein acts by inhibiting DNA repair
  39. Adult T cell Leukemia clinical
    same as any leukemia - anemia, fatigue, tendency to bleed
  40. Adult T cell Leukemia diagnosis
    • detecting serum antibodies
    • finding characteristic cancerous cells in a blood smear
  41. Adult T cell Leukemia treatment
    chemotherapeutic drugs
  42. Adult T cell Leukemia prevention
    • usual methods for blood-borne diseases and STIs
    • screening blood units especially important
    • testing pregnant women and warning them not to breastfeed or pasteurize their milk
  43. other cancers caused by viruses
    • primary liver cancer - Hepatitis C virus
    • Kapsoi's sarcoma - human herpes virus 8
    • some forms of Hodgkin's diseases - EBV
    • breast cancer - bovine leukemia virus?