Cellular Injury and Adaptation Flashcards
In response to a cancer caused by the PML-RAR-alpha fusion gene which leads to disseminared intravascular coagulation, what is an accepted drug treatment?
ATRA - All trans retinoic acid
Causes of cell injury can be instrinsic or _. Examples of _ are hypoxia/ischemia, physical, chemical, immunilogic, nutiritional and infection
Acquired
What is thought to happen to cells when an injury is mild and transient? What is though to happen when the injury is severe and progressive?
Reversible injury, back to normal
Irreversible injury, eventually leading to cell death
What are the 2 major types of cell death?
Necrosis and apoptosis
Arrange the following events in the order that they occur
- Gross morphiological changes
- Ultrastructural changes
- Biochemical alterations
- Changes visible by light microscopy
Biochem - > Ultrastructural -> Light changes -> Gross morphological changes
What type of conditions have to be met for morphological changes to be visible under a light microsopy? (i.e. what type of injury)
Prolonged and severe injury
What is the difference between atrophy, hypertrophy and hyperplasia?
Atrophy - loss of tissue / cell size
Hypertrophy - Increase in cell / organ size
Hyperplasia - increase in number of cells produced
What is metaplasia?
Cells change their differentiation
What are 4 sites of vulnerability regarding cell injury?
Membrane integrity
Aerobic respiration
Protein Synthesis
DNA integrity
How can mitochondria contribute to cell injury / death?
When damaged, source of cytochrome C which activates caspases
How can calcium influx contribute to cell death / injury?
It can increase mitochondrial permeability, increase activation / release of cytochrome C and caspases
Neurotoxicity
Reduced ATP, Mitochondrial damafe, Increased calcium, ROS, Membrane damage and protein/DNA damage can all contribute to cell death. Which is the culprit in most cases?
Unclear, usually a combination of several of those factors
What are 2 proteins that can be quantified in a patients blood following an MI due to membrane damage?
CK - MB
Troponin
How does a mitochondrion respond to ischemic conditions? What product in reduced because of this response?
Reduced oxidative phosphorylation (no oxygen)
Reduced ATP made
What type of cellular damage would cause the following when looking at mitochondria:
- Reduced protein synthesis
- Increased lipid deposition
- Clumping of nuclear chromatin
Ischemia
Regarding the following ions / molecules, what would you expect following mitochondrial damage due to ischemia?
- Sodium pump
- Calcium, water, sodium, potassium
Decreased pump activity
Influx - Calcium water and sodium
Efflux - Potassium
What are 3 specific events that can lead to mitochondrial dysfunction?
Increased cytosolic calcium
Increased ROS (oxidative stress)
Lipid peroxidation
Membrane integrity can affect whether mitochondria initiates apoptotic or necrotic mechanisms. Explain.
If both mitochondrial membranes are impaired (loss of membrane potential), you get necrosis
If only the outer membrane is impaired (Cyt C, other pro-apoptotic proteins), you get apoptois
Prolonged increase in intracellular calcium levels can lead to cell death. What are 3 sources? What is the normal cytoplasmic level of calcium vs. extracellular levels?
Mitochondria
ER
Extracellular space
0.1 micromolar vs mM level extracell.
What are 4 enzymes mentioned that are activated by calcium?
Phospholipase
Proteases
Endonucleases
ATPases
What are the 4 free radicals / ROS molecules mentioned in the notes?
Superoxide radical
Hydrogen peroxide
Hydroxyl radical
Peroxynitrite anion
Which ROS is made from 2 superoxide molecules? Which depends on water ratiation for its formation? Which is formed from an endogenous vasodilator?
Hydrogen peroxide
Hydroxyl radical
Peroxynitrite anion (nitric oxide)
What is the enzyme used by immune cells to generate superoxide for killing bacteria? What disease develops if this enzyme in not functional?
NADPH oxidase
Chronic granulomatous disease
Excess O2 (e.g oxygen therapy in COPD), inflammation and reperfusion following ischemia are all related to reactive oxygen species because _.
They are all potential sources of ROS.
What is the enzyme in neutrophils that is thought to generate ROS following reperfusion?
Xanthine Oxidase
What is the enxyme within mitochondria that is able to generate hydrogen peroxide from superoxide? What type of reaction generates a hydroxyl radical from hydrogen peroxide? What is the necessary cofactor?
Superoxide dismutase
Fenton reaction
Hydroxyl radical (very reactive)
Which can cause injury: Too much ROS production or inadequate defense against ROS?
Both can cause injury
What are 2 antioxidant vitamins that have been used in drug trials to prevent ROS injury? (Few trials have shown benefit)q
Vitamin A
Vitamin E
In cases of acetaminophen toxicity, what molecule when free can cause severe liver injury? What molecule is normally present but can become depleted if too much acetaminophen is ingested? What can be used to treat people in cases of tylenol toxicity and what does it accomplish?
Free NAPQI
Glutathione
N-acetyl-cysteine
How are anoxia and asphyxia different?
Anoxia - lack of oxygen delivery
Asphyxia - Lack of oxygen from not breathing (a subtype)
Group A - Loss of ATP, glycogen depletion, reduced intracell pH, failure of membrane transport systems and detachment of ribosomes
Group B - Membrange damage, intracell release of lysosomal enzymes, massive calcium influx
Which of the 2 groups represent reversible damage? Which is irreversible?
Reversible - A
Irreversible - B
What might be obsevrved microscopically in response to reduced intracell pH? What about in response to membrane transport systems failure?
reduced pH - Clumping of nuclear chromatin
failure of transport - Edema
What are signs of loss of membrane integrity?
Phospholipase activation
Cytoskeletal abnormalities
Membrane blebs, loss of microvilli and mitochondrial swelling are all signs of _. Is this reversible or irreversible? What is the caveat?
Cell swelling
Reversible if early