Reference no: EM132416771
Imagine that you work at the medical examiner's office for a major metropolitan city. As Chief Medical Officer, you investigate suspicious deaths and provide toxicology services for the county. Unfortunately, it's been a busy week. In the past five days, seven people have died, all with similar symptoms. It is your job to examine the data and determine the cause of death for these victims.
The first was a 12-year-old girl. Her parents said that she was awake in the middle of the night complaining of a stuffy nose and sore throat. They gave her an extra strength Tylenol and sent her back to bed. At 7am the next morning, the parents discovered that the girl had collapsed on the bathroom floor. An ambulance rushed the girl to a nearby hospital, where she was pronounced dead.
That same day, paramedics found the second victim unconscious on his kitchen floor after what they thought was an apparent heart attack. Sadly, the victim's brother and fiancée also collapsed later that night while the family gathered to mourn his passing. Both had taken Tylenol to help them cope with their loss shortly before collapsing; neither survived. In the next four days, four other similar deaths were reported, all in the same neighborhood and all with similar symptoms.
Autopsy Report
- Immediate cause of death was hypoxia (suffocation or lack of oxygen).
- Tissue sections from heart, lung, kidney, and liver all show massive cell death.
- Staining with specific dyes showed major mitochondrial damage within the affected tissues.
- Oxygen levels in the patients' blood were approximately 110 mm Hg (normal range is 75 - 100 mm Hg).
Detailed analysis of the damaged cells showed that ATP levels in the mitochondria were very low. Levels of pyruvate and acetyl coenzyme A (CoA) were normal. You begin to suspect a malfunction of a specific cellular metabolic pathway and so you request a more detailed analysis of the sub-cellular components of the affected cells from the autopsy. The levels of key metabolites are reported below:
Metabolite . Average Patient Levels Normal Levels
Glucose 99microliters 100 microliters
Pyruvate 27 microliters 25 microliters
NAD+ . 10 microliters 75microliters
NADH . 400 microliters 50microliters
1) For each metabolite listed in the table, describe its role in cellular respiration. Specifically, are they substrates or products? In what reaction?
You are now convinced that you know the cause of death for these victims and quickly report it back to the police as this is a very dangerous situation. You started to suspect poisoning and ran a blood test for various poisons. The test of all seven patients came back positive for cyanide. Cyanide irreversibly binds to cytochrome c oxidase (CcOX) of the electron transport chain and prevents the transfer of electrons to oxygen, the final electron acceptor.
- What affect would cyanide have on the electron transport chain and the production of ATP? Explain your answer in detail! (Hint: Describe the role of ETC, what is the specific link between what cyanide can its effect on ATP production?)
- Explain why the patients died of lack of oxygen while their blood oxygen levels were normal.