Virus to blame for blood pressure

Virus to blame for blood pressure

US Scientists have discovered that a common human viral infection may be linked to hypertension, also known as high blood pressure.

Writing in PLoS Pathogens, Beth Israel Deconess Medical Center researcher Clyde Crumpacker and his team infected mice with the rodent equivalent of CMV (cytomegalovirus), which infects 80% of human adults. They found that, compared with uninfected controls, the CMV-exposed animals had significantly higher blood pressure in the weeks after the infection.

They also fed a second group of mice on a high-fat diet and infected half of them with the virus. In the CMV-exposed group the animals again developed hypertension but also showed signs of early atherosclerosis (arterial disease).

To find out why, the team studied the animal's blood vessels and found that the virus was establishing a persistent infection in the vessel wall that led to the production of inflammatory hormones called cytokines including IL-6, TNF-alpha and MCP-1, which have been linked previously to vascular disease. The team also found increases in the activity of two genes that directly control blood pressure - renin and angiotensin.

Next, to find out whether the results also apply to humans the team infected human umbilical cord blood vessels with human CMV with the same results. These findings are important because CMV is part of the herpes virus family, members of which characteristically establish life-long "latent" infections, meaning that CMV is well-placed to provoke long-term injury to blood vessels that could lead to vascular disease. The next step will be to discover whether there is a real association between human onset of hypertension and CMV infection, which increases in prevalence with increasing age, just like blood pressure diagnoses...

Does snow cool the world by reflecting light?

Does snow cool the world by reflecting light?

Well, the thing about snow is that it’s quite reflective compared to bare ground. A good thick snow cover will reflect back up to 80 percent or even more of the sunlight that’s falling on it. Whereas bare ground or grasslands might only reflect 10 or 20 percent of the sunlight falling on it and so, the sunlight warms it up considerably. So, if you replace that bare ground by snow cover, then a lot of the sunlight that would’ve heated the ground just gets reflected back into space. So, if you remove a snow cover by ploughing it up or sweeping it away or whatever, revealing the bare ground underneath, then the ground is going to absorb a lot more sunlight, and will warm up a lot more quickly than if the snow were there. We are having an effect on the reflectivity, the albedo of the planet by changing land use for instance; cutting down forests and replacing them with grasslands. But that generally has the opposite effect, forests absorb quite a lot of sunlight, grassland is less reflective. People have suggested that we could partially offset global warming by painting the roofs of all of our buildings white. I think some calculations have been done that have showed that this will be a good thing, but it wouldn’t have a very large effect because you're only talking about a rather small area of the planet that you'll be changing the reflectivity of.

Why is chocolate toxic for dogs?

Why is chocolate toxic for dogs?

Yes. Chocolate, unfortunately, is toxic to dogs. And the reason for that is because it contains a compound called theobromine. Theobromine and caffeine are both present in chocolate but theobromine is the problem. They’re both methyl xanthines. In dogs, theobromine is very long lasting. So it’s got a very long half-life of about 18 hours. Whereas in people, the half-life is only two or three hours. And people readily absorb the theobromine.

It’s just a fact that every species has a different metabolism. We see differences between dogs and cats. With certain drugs, say for example, you shouldn’t give a cat paracetamol whereas dogs can tolerate paracetamol. So it’s just a species difference; probably down to different enzymes that are present in the system.

So how much theobromine is toxic, you might ask yourself. So if a dog eats a couple of M&Ms, that’s not going to cause any problem. The toxic levels vary from 20 mg per kilogram of theobromine to about 150 mg per kilogram of theobromine. So what does that mean in reality?

Well, putting into a typical scenario, if you got a labrador and that ate a 200 gram bar of dark chocolate, that, potentially, is enough to kill your dog. So it’s actually not very much. And the big problem this time of year is someone gives you a box of chocolates, wrapped up, and you put it under the Christmas tree, and the dog eats the box of chocolates. If that happens you certainly should call your vet as soon as possible.

Can we create artificial nerve signals?

Can we create artificial nerve signals?

Yes we can. We actually know quite a lot about how nerve information travels. If you can imagine a nerve cell as a bit like a long straw, with sides and a space in the middle - what nerves do is to move positively charged ions, in this case sodium ions, from the inside of the nerve, to the outside world. So the inside of the nerve is a bit negative compared to the surroundings.

When a nerve impulse travels along a nerve, what happens is that some "positive" (some sodium) goes back inside the nerve through tiny pores, which are on the surface of the nerve. This is called de-polarising the nerve, and it makes that section of the nerve become, transiently, a bit positive.

Now this does two things; it starts an electrical signal rather like a Newton’s Cradle running inside the nerve, but it also activates other little channels and pores on the surface of the nerve a bit further downstream. They open and let in some more "plus" to sustain and maintain the propagation of the signal. In a big nerve, this signal is actually travelling along at something like 100m/s.

The impulse (or action potential) only goes in one direction though because, in the opposite direction - where it’s just come from, the nerve pumps the "plus" back out again, so it goes back to being net minus and the nerve resets itself.

This process happens in milliseconds, so you can literally conduct hundreds if not thousands of these impulses down a nerve in less than a second. The information can travel very, very fast.

You can also make this happen by artificially stimulating the nerve. If you apply a little bit of electricity to the wall of the nerve fibre itself you can actually make that process trigger off, and then it self-sustains. The signal will propagate along the nerve to wherever it goes – in both directions.

Scientists use this for a number of reasons; one is that you can artificially activate muscles that way – so if you've been paralysed, for example, you can use techniques like this to restore movement to certain muscle groups by electrically stimulating certain nerves that supply those muscles. Another reason is to use brain stimulation – this has been done quite effectively in Parkinson’s disease. Scientists implant a little electrode in a part of the brain which makes movements and is involved in the same circuit as is affected by Parkinson’s disease. If you stimulate those bits of the brain electrically, you can trigger off impulses in the right way and the right rate to help people who have Parkinson’s symptoms to overcome their symptoms and move a bit more easily.

So, it is possible to re-create nerve signals. At the moment it's fairly low resolution: you’re not stimulating individual nerve cells, you’re stimulating clusters of nerve cells. But at the same time, you can do that.

Also, if you listened to last week’s programme, you’ll know that we talked about cochlear implants, which are things that basically stimulate the nerve that conveys hearing information into the brain stem. They’re doing effectively the same thing – stimulating nerve cells directly to send sound information into the brain.

Do rockets punch holes in the ozone layer?

Do rockets punch holes in the ozone layer?

we know that the major culprit for making holes in the ozone layer are chemicals called CFCs — chloro-fluoro carbons. These are things that were used in aerosols, even in aspirin inhalers, but also in fridges as refrigerants, and they were used in huge amounts until the Montreal Treaty came in, in the late 80s to try and ban them. What provoked that was that a group of scientists including Brian Gardner had actually noticed this massive hole opening up over Antarctica in the mid-to-late 80s and this hole actually grew to be the size of Australia at its peak. It stopped growing; it’s actually beginning to shrink a little bit now and that’s because we have stopped using these chemicals. The reason that they concentrate down in the Antarctic is because the Antarctic is an isolated continent. It’s completely surrounded by ocean and this creates something called a circumpolar current, and this has a sort of whirlpool-like effect in terms of air; and it draws in and concentrates these molecules over the Antarctic over winter when it’s very dark. They then accumulate in high clouds over the Antarctic and when the sun comes out the following spring the sun breaks down the CFCs and they get turned into reactive chemicals that would then react with the ozone and deplete it. They are, by far, in a way the worst culprit. We don’t send enough rockets and spaceships up into space to make a huge difference, I wouldn’t have thought, in grand scheme of things. So I think although we have to be environmentally conscious, I think the benefit of sending rockets into space in terms of what they can do for satellites and furthering research is far greater than the small bit of damage they might make to the ozone layer. So I think on the whole, probably not, it’s probably more a man made, anthropogenic problem.

If you don't cut and /or wash your hair, does it grow any slower?

If you don't cut and /or wash your hair, does it grow any slower?

Unlike most other mammals, we have a very specific personal care and hygiene regime. Washing doesn't affect the hair growth itself except for some effect you may get from massaging the scalp as you are washing the hair by ensuring optimal blood circulation in the scalp, which may have some positive benefits for the hair follicle itself. Shaving does not impact on the quality of the actual hair fibre produced in that the hair is a dead entity above the surface of the skin.

There is a perception of thickened hair re-growth because if you were to cut it with a sharp instrument like a razor you would end up getting a sharpened end of the hair at its thickest point rather than that more fine, tapered end. Hair growth is very important for the success of the mammal and nature has provided enormous back-up systems to ensure that the hair continues to grow. In the wild you can imagine the loss of a coat would really be disastrous for a mammal in terms of regulations or camouflage etcetera. As a result the skin has invested enormous power into maintaining the hair follicle. That's why it's hard to grow when you want it to grow or stop growing when you want it to stop growing. That's because the principal driver for hair growth is hormonal, especially in those areas of the body with changed hair pattern after puberty.

There's a lot of clinical evidence to suggest that if you have abnormalities of the endocrine system or the hormone system you can have altered patterns of hair growth: either too much or too little.

What dictates the frequency of waves?

What dictates the frequency of waves?

The frequency of ocean waves depends on the wind speed, the time that the wind has been blowing and the length of the sea that it is been blowing over which is what we call the fetch. We actually prefer to talk about the period of waves, which is the inverse of frequency because people like to think about numbers greater than one rather than thinking about small decimals. If you started with the wind blowing over calm water, the waves start with small heights and short lengths but these steadily increase. In deep waters, the waves with the longer lengths travel more rapidly and the growth continues until the speed of the waves is about the same as the speed of the wind when it can’t put any more energy in. And we describe this as a fully-developed sea. There’s actually been a mixture of periods and people are quarreling about how you define the period in the mixture of them. Real seas often have a spectrum with more than one peak, showing that the waves are coming from more than one place or maybe that the wind speed changed while they were growing. Periods in seconds of the same sort of order as wind speeds measured in meters per seconds, a bit more or a bit less depending on how you define your period. And most sea waves have periods in the range of 5 to 15 seconds with the longer ones coming when you had a really fast wind blowing for a long time over a long bit of sea.

Can lightning re-start your heart?

Can lightning re-start your heart?

Firstly the short answer is yes, it is possible that being struck twice by lightning would firstly stop your heart and then restart your heart. The answer is a bit more complicated than that though. The heart cells maintain a voltage drop across them which controls the inflow and outflow of ions. These ions allow the heart to beat. If the heart’s struck by lightning that voltage drop is immediate and the heart will contract. Unfortunately if the lightning strikes the heart at the wrong part of its relaxation the cells will not contract together, rather chaotically. The heart will enter a rhythm called fibrillation. This doesn’t allow it to pump. For that reason the pulse would stop and the heart would be said to be arrested.

If a second strike of lightning or an electric shock occurred at the same point when a heart was fibrillating it would be possible that the heart cells would all contract together in a more ordered fashion. However, there is a problem. The heart could also be struck by lightning and instead of going into this fibrillating chaotic rhythm it could go into no rhythm at all. It could quite simply not beat again. That’s called asystole. It doesn’t end there unfortunately, our poor unfortunate victim also suffers elsewhere. It’s likely that the chest would become relatively stiff and the chest muscles would go into spasm. These muscles take a lot longer to recover than heart muscles so it would be very unlikely that your victim would be able to breathe again. For that reason, although the heart may well restart the victim may well die.

How long would it take to wipe all trace of man from Earth?

How long would it take to wipe all trace of man from Earth?

Thinking first in terms of archaeological timescale if the human race were to become extinct tomorrow then our buildings and roads would gradually decay and possibly within a hundred or hundreds of years many buildings would start to collapse. The sturdier stone built buildings would stand a lot longer than this as we know because we still have Greek Temples and Egyptian pyramids with us today. If we think in terms of those ancient civilisation sit will only be a few millennia before our city would firstly be overcome by vegetation and then would be buried by silt and sediment. If you consider the fabrics used in modern day construction: reinforced concrete, plastics etcetera these would certainly survive the burial for at least as long as the two million year-old stone tools dating from the early humans from Africa, for example. If we think in terms of a geological timescale – this country and indeed most of Europe has been under the sea for a much greater period of geological history than it has been land. The one thing we can be certain of is that sea levels will rise again and this country will be flooded once more by shallow sea and then all of our cities will become deeply buried by marine sediments. Over geological time, over millions of years they’ll be preserved in a rock stratum in just the same way that dinosaurs are preserved in rock strata from 65 million years ago.

When we consider that the oldest fossils we have on Earth are 3 and a half billion year-old single-celled microscopic, soft-bodied bacteria. If such tiny and delicate organisms can survive for that long then certainly the robust skeletons of Homo sapiens can survive for similar timescales. In actual fact organisms that live in the sea are much more likely to be fossilised than organisms like ourselves that live on land. So human fossils will always be rather scarce. We know this already because although hominids have been around for say five million years the actual numbers of fossil human skeletons is very low. Certainly some of us will be fossilised and we will survive buried in rock strata. To answer the question, when the human race does eventually become extinct, as it certainly will, although evidence of our existence will disappear from the Earth’s surface relatively quickly – say within a few millennia – evidence of our existence will survive buried at depth probably for as long as the planet survives.

Would someone with a psychiatric disorder be better able to pass a lie detector test as they may not feel remorse?

Would someone with a psychiatric disorder be better able to pass a lie detector test as they may not feel remorse?

Old-fashioned lie detectors like the polygraph only detect stress. If the lack of remorse meant that the interviewees had reduced stress levels that would help them pass. Our lie detector, Silent Talker, makes its judgement on non-verbal behaviour: crudely what people call body language. Silent Talker can detect stress but lying involves other factors. We can only juggle a certain number of mental variables at once while we’re thinking. If we’ve got to try and maintain a whole load of different factors about an imaginary story it’s very difficult to do all the mental processing to keep that consistent. That’s what’s known as having a high cognitive load which affects non-verbal behaviour. Also duping delight occurs when liars get a kick out of getting a lie across successfully and again this affects non-verbal behaviour. In one of our own experiments on the general population we taught silent talk to recognise guilty feelings the participants felt while they were lying. When we added this information to the general lie detection we got more accurate classifications. In another independent study conducted by a different university using Silent Talker it was found that Silent Talker was effective at detecting lies told by psychopaths in interviews. So there we have it: evidence that remorse is a factor in the general population but also evidence that in the case of one disorder it’s not the only factor.