prion

There's an excellent page on kuru on wikepedia. It only happened in one group of people in Papua New Guinea, not Africa. Creutzfeldt Jakob Disease is different and the vast majority of CJD is sporadic - i.e. people just develop it for no obvious reason. Probably what happened with kuru is someone in the tribe had a sporadic case of CJD, then when the brain was eaten (as part of the funeral), the prions infected other people. Except the disease they got had very different symptoms to CJD and was called kuru. Then when those people were eaten it got spread even more, etc. Mad cow disease probably started the same way, one cow had a sporadic case of BSE and then got 'recycled' into the food chain and it spread that way. Then when people ate the cows they got variant CJD, which is a different thing from 'normal' CJD. It's not just the brain tissue that's infectious. For example, at least one person has caught variant CJD from getting a blood transfusion from someone else with vCJD.

In theory it's right up my alley but I don't think anyone knows exactly! Some mechanisms have been excluded though. It's not due to loss of normal prion protein (PrP) function because PrP-knockout mice don't have neurodegeneration. It's not simply due to the presence of PrPSc as people have tried putting bits of infected brain into the brain of PrP knockout mice and no damage is done to surrounding tissue even if the PrPSc migrates into it. It's quite possible an intermediate in the folding pathway between normal PrPC and PrPSc is neurotoxic, and the PrPSc build up is not relevant. In support of this, animals and people have died of prion disease with little or no PrPSc. This has also been considered as a possibiliy in other amyloid disease like Alzheimers and Huntington's - actual amyloid fibrils don't seem to be neurotoxic. It's even been suggested that formation of amyloid may be a protective cell mechanism to get rid of damaging misfolded protein. Another theory that I like that could go along with the previous idea is that cell death could happen when the cell's protein degradation machinery gets overloaded by all the abnormal protein (as PrPSc is resistant to proteases) and bursts open, releasing all the digestive enzymes. Then the death of that cell would release all the contents to infect the neighbouring cells, and so on. This matches the spongy/holey patterns in the brain that occur. Also mice show the same neurodegeneration when protein degradation is inhibited. There have been some speculations that abnormal cleavage of the protein could make a peptide that can insert into membranes in a damaging way and be neurotoxic that way. Some research groups are passionate about the possibility that abnormal PrP could bind metal ions in an abnormal way and cause oxidative damage, but other groups are still sceptical about that. The reason the CNS neurons are selectively damaged is because that's where PrP is most highly expressed. Though it's expressed at low levels everywhere and it's now known that the blood of people with variant CJD is potentially infectious. So that's where things are at the moment! The hot topic is PrP folding, trying to work out what causes it to misfold and what forms are toxic to what cells...lots of cell culture etc. I left that field a couple of years ago though. Got fed up of containment labs

This is only true for 'normal' flu, i.e. the ordinary strains of flu that we are familiar with and that do the rounds every winter. The type of flu that causes pandemics is totally different, it is a virus that has mutated so that we have no immunity to it, because our species has never encounted it before. There would be totally different effects, mainly that it would infect many more people and would kill very many people. Also the pandemic flu of 1918 was more likely to kill people who were young and previously healthy, as their inflammatory response was so much more dramatic. I think to a point this was also true of the pandemics in the 50s and 60s - my friends uncle died suddenly of flu in the 60s having been young, fit and healthy. It worries me that in the event of a pandemic people will campaign for the very old and young to be vaccinated/treated when they are not the most vulnerable in those circumstances. It surprises me that people get quite blase about flu when it regularly kills thousands. In the UK a few years ago there was a bad epidemic and every hospital had to have refrigerated trucks outside to hold all the bodies, yet it's been totally forgotten and people can't understand why there so much hype when we are facing a strain that is vastly more dangerous that that. By the way thanks Biomat for drawing attention to the paper - I wasn't aware of that one. Thank goodness it was done at the CDC, heaven knows what precautions they had to take with their containment labs.

Loads of people tried to protect themselves like this in 1918 and it didn't help. There's a great book on the 1918 pandemic called "Catching Cold". If anyone is in any doubt about the hype over bird flu I'd advise them to read it.

Your body works very hard to keep things like sodium at an absolutely constant concentration in your blood. So if you had more than the normal amount of sodium in your blood, in theory your body could tell the kidneys to hold a bit more water back to 'dilute' the sodium and keep it at the same concentration, giving you higher blood pressure (due to the extra fluid). But I don't see how this scenario would happen, because the kidneys can just excrete excess sodium. Maybe there's a limit to how much they can get rid of all at once, I don't know.

Cardiovascular disease!! "Hypertension is a major risk factor for CVD [cardiovascular disease] and the most common risk factor for the development of HF [heart failure]...Aggressive lowering of BP is critical to help reduce the risk of CVD and help prevent the development of HF." The burden of cardiovascular disease: following the link from hypertension to myocardial infarction and heart failure.

Interesting, I didn't realise it had been studied in detail at the molecular level. There still seem to be a lot of unanswered questions though. It reminds me of the issue of light affecting circadian rhythm - when people knew for ages that certain wavelengths of light affected sleep/wake cycles but just couldn't think how, then eventually they found a whole new photoreceptor in the eye. Maybe something similar will happen with this area

yeah: one fungus, lots of fungi. sorry if that wasn't very clear

afraid I don't know it in much more depth than that. I think the increased pressure causes changes in the composition of the vessel walls, with thickening and increased amounts of collagen being laid down and a loss of elasticity. I think this somehow aggravates the blood pressure problem, making it a vicious circle. And I think the changes in the vessel walls make atherosclerosis ie fatty deposition in the blood vessel walls more likely or make it develop faster. More fatty plaques means more risk of them rupturing and causing a blood clot, leading to a heart attack or stroke.

oh I'm just going to have to be different again and say fun-gee. No latin or greek word would ever be pronounced fun-guy, it sounds totally American however people just seem to pick which one they like, I don't think there's a consensus and the singular is fungus! a type of fungus, a fungus, lots of fungi! You wouldn't say "a species of trees" or "a breed of dogs". And fun-j-eye is just silly

ahh prions.... my specialist subject. I was going to launch into some detailed essay on protein folding, but I think the magnet analogy is really good! Normal, healthy prion protein (that everyone has) is made of alpha helices, 'bad', infectious prion protein is made of mainly beta-sheets. No one knows exactly (at the molecular level) how the infectious beta-sheet prions force the normal helical protein to change its shape, but experiments have shown that the normal protein definitely interacts with the beta sheet prion form and then changes its structure.

over long periods of time high blood pressure damages the walls of blood vessels, so people are more likely to have heart disease and strokes, for example.

but has anyone actually correlated MHC/HLA with odour? I understood it was just speculation: i.e. from the discovery that people on average tend to choose the scent of people with different HLA to them, it was speculated that HLA might somehow influence the way you smell? Association doesn't prove causation, I mean if unrelated people smell different because of some other genetic effect on odour, you'd still get the same result in the T-shirt experiment.

aah now according to this online dictionary the latin 'root' comes from the greek work enkephalos...I think we'll have to agree to disagree

I'm not an immunology expert but my understanding of it is that HIV attacks T helper cells (CD4+) cells. This is why people with HIV have "CD4 counts" done on their blood samples - to see how many/few T helper cells they've got. T helper cells are pretty important for an immune response to be mounted against anything - they kind of help to activate different bits of the pathway and generally get things going, including the B-cells that make antibodies. So the reason the immune system can't attack HIV is because HIV has got to the immune system first. When people have HIV it's not just HIV that they can't get rid of, they are susceptible to any infection, for the same reason. The body does make antibodies to HIV - I think often when people are tested to see if they've got HIV it's actually the antibodies against it that the test looks for. But it's never enough because the immune system is disabled by the virus.

You can't 'filter' out alcohol as it's dissolved in the blood. You'd have to do dialysis. Not a particularly convenient or quick option, I think it takes a few hours to set up and a few more hours to do its job. It's done sometimes as a last resort in cases of poisoning. you couldn't inject a gas directly into the blood, if you get bubbles in your blood they block blood vessels and can be lethal, this is what causes the bends in divers when they surface too quickly. Again you'd have to have some kind of big heart/lung set up like they use in heart surgery, not very practical.

yes I know I noticed that! I'm going to ask everyone at work now what they say! (I work in a hospital).

with a K sound, always. I've rarely heard it with an 'S' sound and it sounds bizarre to me. But maybe it's different in different places. I think in the UK people tend to stick to a more 'european' pronunciation and spelling. Like Haem Vs Heme, etc. I used to work for a professor who insisted "apoptosis" was pronounced apoh-tosis ie with no second 'p' sound. On the basis that "ptosis" on its own was pronounced 'tosis'. Haven't heard that anywhere else though

I'm going to say en-keph-alitis just to be different. I used to do research in a neurology hospital where they were studying encephalopathies and they all pronounced it with a K sound (I'm in the UK though). It comes from the Greek word for brain: enkephalos

I don't know what you mean by a "healthy heartbeat"? The way that your heat beats doesn't have much to do with haemoglobin (I can spell, I'm just British...). Haemoglobin is the red stuff in red blood cells and carries oxygen.

Can you not design it yourself? I mean design one from the sequence of whatever bit you want and then order it from a company that makes oligonucleotides? Isn't that what most labs do? I take it you're a student - ask where other people get their primers from?

"consilience" anyone?

f(27)

I'm pro abortion but as far as the 'rape' example goes, I'd be more concerned about the welfare of the child. Even if a child is adopted, they have a right to know that and to know who their birth parents are. How do you tell a child that 'your father raped your mother'?

codeine metabolises to morphine in the body, as does heroin (diamorphine) so is potentially just as addictive, it's just a very different method of delivery and different concentration of it in your body