Exam 2- Tox

difference between mutation and polymorphism?

occurs in less than 1% of population: mutation

more than 1% : polymorphism

what percent of the population has an increased risk of adverse drug reaction?

40%

non synonymous (missense) vs synonymous (sense)

non synonymous (missense): AA substitution

synonymous (sense): no AA change

where in a gene would a mutation most likely alter a protein?

in the exon

what does a mutation near the exon/intron border do?

change the number of exons

what does a mutation near the promoter/enhancer do?

alter cis/trans acting elements

what does a mutation in the intergenic region do?

unlikely to affect protein sequence, may alter 3º structure

compare three methods of DNA prep:

whole blood: high quality
buccal epithelial cells: low yield
whole saliva: high percent non human DNA

describe the Sanger assay

includes ddNTP for DNA chain terminator

describe microarray

determines genotype in terms of 2 CYP enzymes

describe taqman

fluorescent nucleic acid probe to detect and quantify specific PCR products

what was the first FDA approved pharmacogenetic test?

Clopidogrel is ____ by _____
list polymorphisms and their effect

is activated by CYP 2 C19
1 is WT

2 and 3 are not active- cause no therapeutic effect

17 is increased function

Warfarin is ____ by _____
list polymorphisms and their effect

metabolized by CYP 2 C9

1- WT

2 and 3 are less active: need to decrease dose because less clearance, increased bleeding risk

Warfarin normally ____ VKORC1

what would a polymorphism in VKOR do?

normally inhibits

polymorphism would increase sensitivity because less enzyme is present a lower dose of warfarin is needed

Tamoxifen + Codeine are ____ by _____
list polymorphisms and their effect

activated by CYP 2D6

(tam is prodrug)

1+2 are WT
3-6 are not active

9-41 have a decreased function

3-41 dont have same effect as WT

Tacrolimus + Cyclosporine are ____ by _____
list polymorphisms and their effect

metabolized by CYP 3A5

1 is WT

3,6,7 are not active

poor tacrolimus metabolism → organ rejection

5-FU is ____ by _____
list polymorphisms and their effect

metabolized by DPD

1,5,9 are WT

2,13 not active- TOXIC BUILDUP RISK

Azathioprine (immunosupp) is ____ by _____
list polymorphisms and their effect

activated to 6MP and metabolized to 6MMP (inactive) by TPMT

1 is WT

2,3,4 are not active: can cause dangerous build up and bone marrow tox

Irinotecan (chemo) is ____ by _____
list polymorphisms and their effect

activated to SN38 by carboxylesterases and metabolized by UDP-Glucuronosyl transferase 1A1

1- WT

6,28- not active

Isoniazid (TB antibiotic) is ____ by _____
list polymorphisms and their effect

metabolized by NAT2

4 IS WT

5-14 is less active, tox build up

what enzyme protects hemoglobin from oxidation and is a source of NADPH in RBCs

G6PD

what drugs create reactive species and should not be combined with ____ polymorphisms

G6PD polymorphisms react w

rasburicase in cancer patients

aspirin and sulfa agents

give 2 types of transporters

P glycoprotein and breast cancer resistance protein (BCRP)

what gene snp causes drug hypersensitivity?

HLA-B

what gene snp causes upregulation of virus immune response in HCV?

IFNL3

DNA mutagenesis initiation involves which types of mutations

point and frameshift

what aids in DNA repair?

alkyl transferases

Compare cancer development promotion and progression stages

promotion: reversible
no direct DNA change, alters gene expression
promoting agents: DES, BPA, dioxin

progression: irreversible
malignant cell population, complex gene alterations
progressor agents: arsenic, asbestos, benzene

what does dioxin do?

induces CYP 450 and increases oxidative stress

What do heterocyclic amines do

become covalently bound to DNA

what does arsenic do

multiple actions: inhibits DNA repair

what does asbestos do?

cell transcription and ROS

three endocrine disruptor mechanisms?

mimicry, blocking, epigenetic

what was the first endocrine disruptor?

DES

why are endocrine disruptors a public health issue?

-age: early exposure

-latency: early exposure has effects later in life

-dose response: dont act through linear response, low dose can have large effect

- epigenomic changes

differentiate plant defense mechanisms:

spines

thorns

prickles

trichomes

spines: modified leaves

thorns: modified branches/stems

prickles: extension of cortex

trichomes: originate from only epidermis (hard, sticky, fragile)

what is the largest plant toxin family

alkaloid

what are alkaloids made of and examples of alkaloids

amine/amino acid derived and have nitrogen containing base

atropine, cocaine, morphine, nicotine, muscarine

what is the most important medical plant toxin family

glycosides

what is a glycoside and examples

upon hydrolysis get sugar and nonsugar

cardiac glycoside (digoxin), cyanogenic glycosides (amygdalin in fruit seeds/pits)

what is a terpene vs terpenoid and example

derived from isoprene. terpene is hydrocarbon and terpenoid has an additional group

geraniol, limonene, linalool

what is a phenol and example

derived from phenols or phenyl + propyl linker

acetylsalicylic acid, methyl salicylate, capsaicin

Wolfsbane/Aconitine:

mechanism:
symptoms:

mech: prolonged activated of voltage gated Na channels. Acts on neurotoxin binding site 2

symptoms: cardiac arrhythmias is the usual cause of death

Yew Trees/ Taxines

mechanism:

symptoms:

mechanism: blocks L type voltage dependent Ca channels

symptoms: circulatory collapse, dec BP

Cardiac glycosides/digoxin

mechanism:

symptoms:

mechanism: inhibits Na/K/ATPase
increases Na and Ca

symptoms: cardiac arrhythmias is cause of death

Strychnine

mechanism:

symptoms:

mechanism: competitive antagonist for glycine neurotransmitter

symptoms: no muscle relax, painful dramatic symptoms

the lambeth poisoner used what toxin?

strychnine

Poison hemlock/Coniine

mechanism:

symptoms:

mechanism: nicotinic receptor agonist

symptoms: paralysis of diaphragm causes death
(no CNS)

Curare/D-tubocurarine + Rocuronium
mechanism:

symptoms:

mechanism: nicotinic antagonist

symptoms: paralytic agent

Atropine (nightshade)

mechanism:

symptoms:

mechanism: muscarinic antagonist

symptoms: dilation, bradycardia, muscarine antidote

Scopolamine (nightshade)

mechanism:

symptoms:

mechanism: muscarinic antagonist, crosses BBB

symptoms: motion sickness, dec oral secretions

what toxin is used in witches flying ointment

scopolamine

Physostigmine (calabar bean) + organophosphates

mechanism:

symptoms:

mechanism: ACh-esterase inhibitor

symptoms: respiratory paralysis

Cocaine

mechanism:

symptoms:

mechanism: indirect sympathetic stimulation: blocks NE and dopamine uptake

symptoms: local anesthetic and vasoconstrictor during surgery

Ephedrine (Ma Huang shrub)

mechanism:

symptoms:

mechanism: release of NE from nerve endings

symptoms: pseudoephed as decongestant

Quinine (Cinchona tree)

mechanism:

symptoms:

mechanism: interferes with parasites ability to digest hemoglobin, Na channel blocker

symptoms: treat malaria, tonic

vinka alkaloids + taxol

mechanism:

uses:

mechanism: prevents mitotic spindle division

uses: cancers

Salicylic Acid (willow trees)

mechanism:

uses:

mechanism: covalently binds COX 1+2 and inhibits PG

uses: analgesia, antipyretic, anti inflamm

Morphine

mechanism:

uses:

mechanism:inhibition at relay neurons in spinal cord

uses: acute and chronic , death due to respiratory

Capsaicin

mechanism:

uses:

mechanism: activates TRPV1 channels in nociceptors

uses: desensitizes, pain relief

give some fungal infection examples

athletes foot, tinea

C. neoformans: lung infection in immunocompromised

histoplasmosis: serious symptoms in immunocompromised

where does mycotox come from and give some mycotoxin mechanism examples

aflatoxin:

ochratoxin A:

ergot:

food molds (cereals, nuts, spices)

aflatoxins: damage liver, DNA

ochratoxin A: kidneys, oxidative damage

ergotism: St Anthony’s fire. Causes gangrenous and convulsions

give two examples of ergot alkaloid derivatives

LSD, anti migraine

give some mushroom toxin/alkaloids mechanisms

muscimol:

Psilocybin:

Mescaline:

Death Cap mushroom:

muscimol: GABA agonist

Psilocybin: 5HT2A agonist

Mescaline: 5HT2A agonist

Death Cap mushroom: RNA pol II inhibitor, inhibits mRNA synthesis

3 stage of death cap toxicity

1) GI
2) stop GI
3) hepatic necrosis, renal dys, death x