Sorry for the long one today, but if you can navigate all the parentheses, I promise you'll learn a thing or two!
Is there such a thing as a good disease? Dis-ease literally means not-good, so it would appear not. But we don't seem to have a better word for an abnormal genetic variation that is actually beneficial. ApoA1 Milano is an aberrant version of apolipoprotein A1, a protein found in high density lipoproteins (HDL ("good" cholesterol)). The very few people that seem have this version of the protein are seemingly immune to atherosclerosis (the hardening of arterial walls, a main cause of coronary artery disease). These real-life X-men have extremely low amounts of HDL floating around their blood vessels and oodles (that's a scientific term) of triglycerides, but show none of the associated ill-effects. If drug companies can find a way to produce this protein cheaply or get the body to produce it through gene therapy, huge strides could be made in combating our #1 killer, heart disease.
Is there such a thing as a good disease? Dis-ease literally means not-good, so it would appear not. But we don't seem to have a better word for an abnormal genetic variation that is actually beneficial. ApoA1 Milano is an aberrant version of apolipoprotein A1, a protein found in high density lipoproteins (HDL ("good" cholesterol)). The very few people that seem have this version of the protein are seemingly immune to atherosclerosis (the hardening of arterial walls, a main cause of coronary artery disease). These real-life X-men have extremely low amounts of HDL floating around their blood vessels and oodles (that's a scientific term) of triglycerides, but show none of the associated ill-effects. If drug companies can find a way to produce this protein cheaply or get the body to produce it through gene therapy, huge strides could be made in combating our #1 killer, heart disease.
TIL: A related protein to ApoA1, ApoB, is the best example of RNA editing. Both ApoB-100 and ApoB-48 are encoded by the same gene. While ApoB-100 is translated in its entirety in the liver, ApoB-48's RNA transcript is changed by one nucleic acid. This small but important edit changes a codon (nucleic acid triplet that codes for one amino acid of a protein) in the middle of the protoprotein to a stop codon, terminating the protein early, effectively creating a totally different protein from the same DNA code.
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| Xanthomas on the surface of knees |
Statin drugs inhibit HMG reductase, the enzyme that allows your body to synthesize cholesterol. Don't we need some of that? you might ask. We consume more than enough cholesterol in our diets; statins just stop us from adding our own to the mix. But I suppose if you are starving in a desert somewhere you should probably discontinue your statin prescription.
The coronary circulation (blood vessels supplying nutrients to the muscle or the heart) perfuses the heart tissue very oddly. The epicardium (outer surface of the heart) perfuses during systole (during ventricular contraction (when blood is pushed out of the heart)) which makes sense in the rest of the body, but the endocardium (inner surface) perfuses during diastole (when the ventricles are being refilled but no blood is flowing out of the heart). Though this doesn't seem to make sense at first (How do you get more nutrients from blood that isn't flowing?), it should with a little more explanation.
Whereas the outer surface of heart muscle is essentially at ambient pressure in the chest cavity, the inner surface is put under high pressure (specifically the systolic pressure (~120 mmHg)) every time the heart beats. This high pressure is easily withstood by the sturdy coronary arteries, but the veins are weak and collapse, stopping flow through the whole endocardium. Flow is returned after the heart finishes its beat (during diastole), allowing the blood to drain and the tissue to be perfused.
Whereas the outer surface of heart muscle is essentially at ambient pressure in the chest cavity, the inner surface is put under high pressure (specifically the systolic pressure (~120 mmHg)) every time the heart beats. This high pressure is easily withstood by the sturdy coronary arteries, but the veins are weak and collapse, stopping flow through the whole endocardium. Flow is returned after the heart finishes its beat (during diastole), allowing the blood to drain and the tissue to be perfused.
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