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DWT Exam 4 > Pathology: Carcinogens > Flashcards

Pathology: Carcinogens Flashcards

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1
Q

What are carcinogens?

A

an agent that is able to damage DNA, resulting in a heritable, nonlethal, mutation that gives rise to neoplasia

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2
Q

What are the three types of carcinogens?

A

Chemical
Radiation
Microbes

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3
Q

What is an important concept to keep in mind about DNA damage and neoplasia?

A

Severely damaged DNA will not replicate, thus toxic agents may have the potential to induce tumors, but @ high concentrations damage & kill cells before this effect is expressed

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4
Q

What do you need both of to cause tumor growth?

A

Initiation and Promotion

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5
Q

What are the characteristics of chemical carcinogen initiation?

A

permanent DNA damage
irreversible

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6
Q

What are the characteristics of chemical carcinogen promotion?

A

promote proliferation of initiated cells
no effect on DNA
reversible

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7
Q

What are the differences between direct acting and indirect acting chemical carcinogens?

A

Direct require no metabolic conversion to be carcinogenic
Indirect require metabolic conversion to be carcinogenic

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8
Q

what are most carcinogens metabolized by?

A

Cytochrome P450 enzymes

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9
Q

What is important about genes that encode Cytochrome P450 enzymes?

A

The genes that encode Cytochrome P450 enzymes are highly polymorphic so differ greatly between individuals

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10
Q

What is the relationship between Alphatoxin B1, hepatocellular carcinoma and TP53?

A

Individuals that ingest alphatoxin B1 at high levels predominantly end of with hepatocellular carcinoma due to a mutation in TP53

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11
Q

what types of radiation causes neoplastic transformation?

A

ultraviolet radiation
Ionizing radiation (alpha, beta, gamma, and x-ray)

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12
Q

What are the normal host defenses against UC radiation?

A

Cutaneous pigments (melanin) absorb irradiation
aromatic portions of amino & nucleic acids also absorb irradiation
free radical scavengers minimize damage

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13
Q

What is the primary target of UV irradiation in DNA?

A

Pyrimidine molecules

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14
Q

How are mutations formed due to UV irradiation in DNA?

A

photon of light is absorbed by DNA thus formation of pyrimidine dimers which forms mutations

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15
Q

What do Pyrimidine dimers result from?

A

The crosslinking of base pairs

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16
Q

How are mutation formed due to free radical-mediated DNA damage?

A

Translocation, direct signal/double strand breaks

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17
Q

What is the primary microbe responsible for microbial carcinogenesis?

A

Viruses

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18
Q

What are the characteristics of oncogenic retroviruses?

A

Insert viral genome into cellular DNA of host

19
Q

What are examples of oncogenic retroviruses?

A

Feline leukemia virus, bovine leukemia virus, avain leukosis virus

20
Q

What are the characteristics of oncogenic DNA viruses?

A

Viral gene encode oncoproteins capable of transforming infected cells

21
Q

How do oncogenic retroviruses cause neoplasia

A

promotors & enhancers control viral gene expression & nearby cells host genes, especially important when inserted near a proto-oncogene

22
Q

How do oncogenic DNA viruses cause neoplasia?

A

often interfere with the proteins encoded by tumor suppressor genes

23
Q

What is an example of oncogenic DNA viruses?

A

Bovine papillomavirus

24
Q

How is Bovine Leukemia virus inserted into the host genome?

A

It is inserted randomly into the genome

25
Q

How are cattle infected with bovine leukemia virus?

A

infected through transfer of blood & blood by products containing infected lymphocytes

26
Q

What are the 3 outcomes of Bovine leukemia virus?

A

1) persistent infection with no clinical signs
2) persistent lymphocytosis
3)Lymphoma: most common in adult cattle

27
Q

How is Feline Leukemia virus inserted into the host genome?

A

It is inserted randomly into the genome

28
Q

How are cats infected with feline leukemia virus?

A

oronasal contact with infectious saliva or urine, in uteros through nursing is also common

29
Q

What are the possible manifestations of feline leukemia virus?

A

Anemia, neoplasia, immunosuppression, immunemediated, diseases, reproduction problems, enteritis, neurologic dysfunction & stomatitis, and lymphoma and leukemia

30
Q

How is Avian Leukosis virus inserted into the host genome?

A

inserted near c-myc

31
Q

How are birds infected with avian leukosis virus?

A

fecal-oral transmission & horizontal transmission

32
Q

How are birds infected with avian leukosis virus?

A

fecal-oral transmission & horizontal transmission

33
Q

What are the possible manifestations of avian leukosis virus?

A

B cell lymphoma

34
Q

How is Gallid Herpesvirus-2 inserted into the host genome?

A

integrate its viral genome into the telomeres of host chromosomes & encodes a telomerase

35
Q

How is Gallis Herpesvirus-2 spread?

A

highly contagious through dander in the environment

35
Q

How is Gallis Herpesvirus-2 spread?

A

highly contagious through dander in the environment

36
Q

What are the possible manifestations of Gallid Herpesvirus-2?

A

T cell proliferations: inflammation, lymphoma, neurotropic

37
Q

What species do papillomaviruses infect?

A

horses, dogs, cattle & others

38
Q

What age of animal are preferentially affected by papillomaviruses?

A

Young animals

39
Q

What does the persistence of papillomaviruses suggest?

A

Immune dysregulation

40
Q

How do papillomaviruses have marked epidermal thickening?

A

viral proteins prevent suprabasal cells from becoming postmitotic and viral protein binds E2F preventing inhibition from Rb

41
Q

What does Helicobacter cause in humans?

A

Gastric adenocarcinoma
Lymphoma
H. pylori

42
Q

What does Helicobacter cause in ferrets?

A

Gastric carcinoma
H. mustelae

43
Q

What is the likely mechanism of Helicobacter?

A

chromic G.I inflammation & attempts @ repair

DWT Exam 4 (5 decks)

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