Rad Bio Flashcards
2 purines are ?
adenine & guanine
2 pyrimidines are?
thymine & cytosine
adenine binds with
thymine
guanine binds with
cytosine
mitosis phases (4)
- prophase
- metaphase
- anaphase
- telephase
what happens in prophase
- spindle forms
- membrane begins to disappear
what happens in metaphase
chrom line up @ equator
what happens in anaphase
migrate to opp poles
telophase main process
division (cytokenesis)
what happens during G1?
rapid growth & active metabolism
S phase fxn & sensitivity?
- DNA synthesis
- least sensitive
G2 fxn & sensitivity?
- prepare for cell division
- highly sensitive
M fxn & sensitivity?
- cell divides
- most sensitive
what happens during G0?
resting phase
linear quadrant model surviving fx = ?
alpha (a)dose + beta (B) dose squared
alpha (a) proportional to:
dose
beta (B) proportional to:
dose squared
tumor display for a/B ratio?
tumors tend to display higher a/B ratio than normal tissue due to lack of repair fxn
tumor typical value of a/B
10Gy
norm tissue typical value of a/B -late effects
3 Gy
LET definition
rate @ which E is deposited as charged particle travels thru matter
EMR mass?
no mass
quantum theory of EMR
E is photon traveling in straight but diverging lines
RBE stands for
relative biologic effect
RBE definition
ability to produce specific biologic response w/diff LET
what happens in chromosome with damaged base?
- change/loss in base
- mutation or abberation
what happens with double strand break chromosome damage?
both chains break
Mammalian cell survival curve shape
semi-log
reciprocal of slope & expression of radiosensitivity of cell population value is?
b/n 1-2 Gy
radiosensitivity = ? Do
low
radioresistant = ? Do
high
high dose curve shape
shallow curve
curve shape for low doses
steep curve
low LET shoulder on cell survival curve
broad shoulder
high LET shoulder on cell survival curve
no shoulder
division delay dependent on
dose
interphase death means
cells die before dividing
repair SLD radiation type
x-ray, gamma only
repair PLD occurs when
post irradiation conditions are modified
inherent sensitivity means
when & if cell divides
Bergonie & Tribondeau stated
cell division critical to selective cell killing
Ancel & Vitemberger stated
inherent susceptibility of any cell to damage by radiation is same but time of appearance of damage is different
appearance of rad damage influenced by ? stress
biological stress
greatest stress on cell- ? necessity
necessity for division
Rubin & Casarett 5 categories of cell populations
VIM, DIM, multipotential conn tissue, RPM, FPM
VIM definition
vegetative intermitotic delay
DIM stands for
differential intermitotic delay
RPM stands for
reverting post mitotic delay
FPM stands for ? & do cells divide?
- fixed post mitotic delay
- do NOT divide
stromal dept found in?
all organs & tissues
3 factors that affect cell/tissue after radiation
physical, chemical, biological
physical factors (3)
- LET
- RBE
- dose rate
large shoulders for neutrons exhibit ? RBE
high RBE than cells & tissues w/small shoulders
dose rate most dramatic at what dose rate?
most dramatic b/n 1-100 cGy/min
high LET exhibits ? dose rate effect
high LET does NOT show dose rate effect
nitroimidazoles mimic
O2
halogenated pyrimidines substitute ?
substitute for base thymidine in DNA
radiation protectors reduce dose by factor of
1.5-2
biological factors (2)
- cell cycle (G, S, G2, M)
- intracellular repair (SLD, PLD)
acute effects have ? a/B ratio
high
late effects have ? a/B ratio
low
structural tissue tolerance
parallel organiz, serial organiz
parallel organization shows pronounced
volume effect (lung)
serial organization shows little
volume effect (spinal cord)
as dose rate decreases cell killing ?
increases= b/c cells continue to progress thru cell cycle & become arrested in G2 phase
acute effect causes depletion of ? cells
parenchymal cells
healing is fxn of ?
dose & organ irradiation
repair
- replacement by diff cells
- only after high doses so regen not poss
hemopoietic system made up of
bone marrow, circulating blood, lymphoid organs
liver rad hepatitis dose
35-45Gy
dose lungs respond to
> 10Gy
radiation nephritis due to
loss of tubules
which part of spine most sensitive
c & t spine more sensitive than L
LD 50/30 rad syndrome whole body irrad dose
450 rad (cGy)
hemopoietic syndrome dose
1-10 Gy
GI system syndrome dose
10-100Gy
CNS system syndrome dose
> 100Gy
russell & russell developed what
stages of fetal development
greatest variety of congenital abnormalities happen when?
23-37 day
fetus most sensitive at what time?
1st 6 wks
