Pathology - Carcinogens

Question 1

Carcinogen

Answer 1

Agent that is able to damage DNA, resulting in a heritable, non lethal mutation that gives rise to neoplasia

Question 2

types of carcinogens

Answer 2

Chemical, radiation, microbes

Question 3

Steps in chemical carcinogenesis

Answer 3

Initiation, promotion, direct acting, indirect, metabolism, target DNA

Question 4

Initiation & promotion

Answer 4

I: Permanent DNA damage, irreversible
P: promote proliferation of initiated cells, no effect on DNA, damage is reversible

Question 5

Direct acting, indirect damage

Answer 5

D: no metabolic conversion to be carcinogenic
I: metabolic conversion to be carcinogenic (majority of damage)

Question 6

What metabolizes carcinogens?

Answer 6

Cytochrome p450 enzymes
Genes that encode enzymes are highly polymorphic differ greatly
Influence ones susceptibility too a carcinogen

Question 7

Example of chemical carcinogen

Answer 7

Aflatoxin B1
(Mutate in TP53)

Question 8

Ionizing radiation

Answer 8

Alpha, beta, gamma, x-ray

Question 9

Radiation vs irradiation

Answer 9

Radiation is the number of photons that are being emitted by a single source. Irradiation, on the other hand, is one where the radiation is falling on the surface is being calculated.

Question 10

Host defenses against UV irradiation (3)

Answer 10

Cutaneous pigments absorb
Aromatic portions of amino & Nucleic acids absorb
Free radical scavengers minimize damage

Question 11

Primary target of UV irradiation?

Answer 11

DNA in pyrimidine molecules

Question 12

How mutations occur in pyrimidine molecules

Answer 12

Formation of pyrimidine dimmers, result from covalent cross linking of base pairs

Question 13

How mutations occur with ionizing radiation

Answer 13

Translocation, direct single/double strand dna breaks

Question 14

Example of microbial carcinogenesis

Answer 14

Retroviruses (FLV, BLV, ALV)
DNA viruses (bovine papilloma virus)

Question 15

Mechanism of retroviruses

Answer 15

Insert viral genome into cellular DNA of host cell, promoters & enhancers control viral gene expression & nearby cellular host genes

Question 16

Mechanisms of DNA viruses

Answer 16

Viral genes encode oncoproteins capable of transforming infected cells, interfere w proteins encoded by TSG

Question 17

3 main outcomes of bovine leukemia virus

Answer 17

Persistent infection w no clinical sings
Persistent lymphocytosis
Lymphoma (common in adults)

Question 18

Mechanisms of feline leukemia virus

Answer 18

Randomly inserts into genome, oronasal contact or urine

Question 19

Manifestations of FLV

Answer 19

Anemia, neoplasia, Immunosuppression, IMD, reproductive issues, enteritis, CNS, stomatitis
Lymphoma, leukemia

Question 20

Mechanism of Avian Leukosis virus

Answer 20

Inserts near c-myc
Fecal-oral/horizontal
B cell lymphoma

Question 21

Mechanisms of Gallic herpesvirus

Answer 21

Integrates viral genome into telomeres of host chromosome, encodes. T cell proliferations (inflammation, lymphoma, neurotrophic)

Question 22

Mechanisms of papilloma virus

Answer 22

Causes cutaneous papillomas, viral proteins prevent suprabasal cells from becoming postmitotic, viral proteins bind E2F preventing inhibition from Rb

Question 23

Helicobacter in humans

Answer 23

Gastric adenocarcinoma
Lymphoma
H. Pylori

Question 24

Helicobacter in ferrets

Answer 24

Gastric carcinoma
H. Mustelae