Does Beer Kill Brain Cells?

09 May 2010

Is there a cure for spots? Why do we cry? Does alcohol really kill brain cells? It's a Question and Answer Extravaganza on this week's Naked Scientists! We find out what makes a Chameleon change colour, why birds fly into windows and how a hair can change colour along it's length. Also, witnessing the birth of stars, the Neanderthal genome and how washing your hands can change the way you think. Plus, Meera dabbles with green gadgets and smell-free toilets in the home of the future, and Dave shows you how to build a hovercraft in Kitchen Science.

In this episode

01:35 - Herschel sees super-massive stars forming

The recently-launched Herschel space telescope has revealed a new way in which massive stars might form - at points where supersonic shockwaves hit clouds of dust and gas.

Herschel sees super-massive stars forming

The recently-launched Herschel space telescope has revealed a new way in which massive stars might form.

Stars are the major building block of the Universe, and our star - the Sun - powers almost all the life on Earth, so understanding the workings of the Sun and other stars like it is very important.

(c) NASA' alt='Artist's impression of the Herschel Space Observatory' >One big problem is that, according to present theories, stars shouldn't get bigger than 8 times the mass of the Sun. This is because the light they produce should blow away the surrounding material before it can become part of the star. Nevertheless, there are many stars of this size in the galaxy, so space scientists know that there must be a piece of the puzzle missing. But investigating this sort of problem has been difficult until now because young stars are surrounded by clouds of opaque dust and gas, which obscure our ability to see what's going on.

However, in May 2009, the European space telescope Herschel was launched. It is the largest space telescope ever deployed and is equipped with a 3.5m mirror and is set up to study the the Infra Red region of the spectrum. This means that it can see straight through the dust that has hampered earlier attempts to witness the births of new stars and it can also see objects that are relatively cool, which means that it can peer into the deepest recesses of space where new stars are forming.

Recently, Herschel spotted a "bubble" of hot gas that is expanding supersonically through a cloud of gas and dust, producing a high density shock wave at the surface. Intriguingly, on this surface, a star is beginning to form and already has a mass of between eight and ten times that of the Sun and is still growing. Shock waves like this might therefore be the way that these stars form.

Herschel has also been sending back beautiful pictures of stars forming in  stellar nurseries and galaxies forming stars in the early universe. There should me much more to come.

03:53 - Meet our Neanderthal ancestors

This week has seen the sequencing of the Neanderthal genome, which helps to answer some puzzles - did humans and Neanderthals ever mate? How many genes do we share..?

Meet our Neanderthal ancestors

A couple of weeks ago on the show we discussed the science of archaeogenetics - unravelling the mysteries of the past in our genes. This week there's been an important step forward in the field, with the sequencing of the Neanderthal genome, published in the journal Science. The new research helps to answer some puzzles, such as did humans and Neanderthals ever mate, and how many genes we share.

Neanderthal reconstructionThe scientists used samples of bones from three female Neanderthals who lived in Croatia more than 38,000 years ago. Then they used the latest DNA sequencing technology to sequence the DNA and build a composite genome - they've got around 1.3-fold coverage, although around a third of the genome is still a bit unclear.  Then came the fun stuff - comparing the Neanderthal sequence to the genomes of humans living in different parts of the world today.

Intriguingly, the team, led by Svante Paabo from Germany, discovered that modern Europeans and Asians share between 1 and 4 per cent of their DNA with Neanderthals - but Africans don't. This tell us that any interbreeding between us and them happened after modern humans had left Africa, but before they spread across Asia and Europe, perhaps around 30,000 to 45,000 years ago - maybe even as early as 80,p000 years ago in the Middle East.  So many people in Europe and Asia have a small but significant Neanderthal component in their genes - including Paabo himself.

The scientists have been comparing the Neanderthal genes with those of present-day humans to try and find the key genes that make us modern - we are around 99.84 per cent identical, but there are some crucial differences. At the moment the  significance of the results isn't completely clear, but there are a number of intriguing differences in genes involved in metabolism, skin, bones and brain development, but we don't know how these relate to physical properties.

The research also allows us to speculate a bit as to how Neanderthals and humans might have interacted together. The researchers think that just a few Neanderthals infiltrated a group of humans, and started interbreeding, rather than a mass mixing of the two species.  We don't know why they kept themselves mostly separate, now that we know there was no biological barrier to interbreeding  - perhaps there were significant cultural differences? For now, there's still a lot more work and analysis to do, but this new genome gives us an intriguing look into our genetic past. And maybe many of us have a little bit more Neanderthal in us than we might have thought.

06:56 - Wash your hands, wash away doubt

Pontius Pilate is probably the most famous person to have washed his hands of a problem, but new research suggests that the act goes beyond just the metaphorical: scientists in the US have...

Wash your hands, wash away doubt

Pontius Pilate is probably the most famous person to have washed his hands of a problem, but new research suggests that the act goes beyond just the metaphorical: scientists in the US have found that washing hands can alter the decisions we make about something subsequently!

Person washing his handsMichigan researchers Spike Lee and Norbert Schwarz, writing in Science, initially asked 40 undergraduates to take part in a "consumer survey" and browse through 30 CDs, selecting their favourite ten and ranking them in order of preference. They were then told that they could choose between either the fifth or sixth CD in their order and keep their selection as a reward for their cooperation.

But before they took their rewards they were first asked to also rate some soap; half the students were told just to look at the soap in the bottle, the other half were also asked to use it. They were then re-presented with the ten original CDs and asked to rank them again, including choosing which of the two they would prefer to keep. Incredibly, those who had not washed their hands clung vigorously to their original preferences, viewing the chosen CD as much more attractive than the one they'd rejected. But amongst the students who had meanwhile washed their hands, this effect evaporated alongside the soap, with the subjects showing much less of a preference for one CD over the other.

The researchers then replicated the result using a second experiment on the taste of jam! This time 85 students were shown pictures of four different fruit jams and asked to pick one from two offered jars as a reward for taking part. Then they were asked, ostensibly as part of a consumer survey, either to examine an antiseptic wipe, or to physically use the wipe, before indicating on a scale of 1 to 10, how tasty each of the two jams - the one they'd previously picked and the one they'd rejected - would taste.

The participants who didn't clean their hands expected their chosen jam to taste significantly nicer than the one they had previously rejected. But for subjects who used the wipe this difference went away.

These fascinating findings suggest that hand washing has impacts beyond just the moral domain. In some way it can erase the traces of previous decisions, preventing us from loading judgements to justify the choices we have made. So next time you're faced with a difficult decision, wash your hands to wash away your prior prejudices, before finally making up your mind!

09:48 - Taking photos through opaque objects

Something which has always tantalised many people ranging from surveillance agencies to the more dubious parts of society is being able to see through opaque objects...

Taking photos through opaque objects

Something which has always tantalised many people ranging from surveillance agencies to the more dubious parts of society is being able to see through opaque objects. If the object absorbs all the light hitting it then this is impossible but if an object is translucent, and scatters light in lots of random directions mixing up the image so much it is impossible for our eyes to decode it, but in theory none of the information about what is behind it is lost.

Nikon D700 cameraSebastian Popoff and collegues at the Langevin Institute in Paris have worked out a way of getting this information back. They have managed to see through a slide covered with zinc oxide particles which to your eyes look white. They have done it by first shining a series of carefully calibrated laser pulses through the slide, and working out what patterns these produce on a camera sensor. From this they can work out what effect the slide is happening on the light, so when they put an object behind the slide, the pattern will change and they can work out from this change in pattern what the object looked like.

This is certainly not going to let us see through a wall, and seeing through frosted glass is still very difficult without a lot of careful setup and illumination, but it may be useful in the short term for seeing through an opaque sample in a microscope, and it has been suggested that the same technique could make a white wall behave like a mirror.

11:27 - Untangling triple negative breast cancer

New work led by Cancer Research UK researchers have discovered why some cancers may be resistant to chemotherapy and radiotherapy – as well as an intriguing link to the breast cancer gene...

Untangling triple negative breast cancer

Breast cancer survival is a real success story for science - now around 80 per cent of women survive for at least five years, compared with just half back in the 70s. But most of this success is in cancers that are fuelled by female hormones, which can be treated with hormone-blocking drugs, or by the HER-2 receptor, which can be blocked with the drug Herceptin. But there are also so-called "triple negative" cancers, which are much harder to treat, where survival is poorer. 

Breast self-examinationNow new research published in the journal Nature today from an international team, led by Cancer Research UK's Madalena Tarsounas in Oxford, Jos Jonkers in the Netherlands and Shridar Ganesan in the US, has discovered why these cancers may be resistant to chemotherapy and radiotherapy - as well as an intriguing link to the breast cancer gene BRCA1.

The faulty BRCA1 gene is found in hereditary breast cancer, where lots of women in the same family have the disease.  Also, around 9 out of 10 triple negative breast cancers are in women with faulty BRCA1, so there's clearly a link.  Sometimes these BRCA1-deficient cancers respond to radiotherapy and chemotherapy - particularly with platinum-based drugs such as carboplatin and cisplatin. But often the tumours develop resistance to treatment and start growing again. Tarsounas and her colleagues wanted to find out why.

The researchers started by looking at cells grown in the lab that lacked BRCA1. Contrary to what you might think, these cells actually don't grow well at all - it's the combination of faulty BRCA1 with other faulty genes that makes cancer cells grow. The researchers then used a  clever trick to randomly knock out genes in the BRCA1-deficient cells, to hunt for genes that made the cells grow again.

They found several - but the most interesting one was a gene called 53BP1, which is normally involved in helping cells to repair damaged DNA. Then they went on to discover that while cells lacking just BRCA1 can be killed with cisplatin or radiotherapy, cells lacking both BRCA1 and 53BP1 were resistant to treatment. So this explains how these cancers may develop resistance to therapy.

The scientists also looked at more than 1,800 samples from breast cancer patients, analysing 53BP1 levels and other characteristics. They discovered that most triple negative cancers also had low levels of 53BP1, suggesting the gene was faulty. And 53BP1 was also faulty in most of the cancers from women with BRCA1 faults.

This research tells us that BRCA1-deficient triple negative breast cancers with low levels of 53BP1 are likely to be resistant to radiotherapy and chemotherapy. So this could possibly be developed into a test to help doctors to decide what sort of treatment to give to women with these types of tumours.

And if we can find out exactly how loss of 53BP1 causes cancer cells to become resistant to treatment, it might reveal new targets for drugs to improve the effectiveness of chemotherapy and radiotherapy and overcome resistance, which would help to save lives.

15:13 - Deciphering the Second Genetic Code

Researchers in Toronto and in Cambridge have made a major breakthrough in understanding how DNA works. More specifically, how the same gene can produce different gene products in different...

Deciphering the Second Genetic Code
with Dr Yoseph Barash, University of Toronto

Chris -   Also in the new this week, researchers in Toronto and in Cambridge have made a major breakthrough in understanding how DNA works.  More specifically, how the same gene can produce different gene products in different types of cells.

To tell us more is Yoseph Barash from the University of Toronto.  Tell us first, if you could Yoseph, what's the problem you've actually been grappling with - what are you trying to solve here?

Joseph -   Basically the problem that we were handling if I put it in one sentence would be to figure out how alternative splicing works.  Of course, that wouldn't mean much if I don't explain what alternative splicing is and why it is important.  So, I'll start off by starting with what people do know and people do know usually about the genes and that they're coded in DNA molecules, and many people know that scientists just about a decade ago mapped the human genome and they found about 20,000 genes altogether in the human genome.  What people usually don't know is that the same gene can actually code for different genetic messages in the form of messenger RNA molecules.  And these different messages can operate quite differently in the cell.

The splicing code forms a genetic networkChris -   So in other words, in different tissues, genes which have the same genetic code can have a different effect by effectively chopping the gene up in a slightly different way, so it turns into a different recipe.

Joseph -   Exactly.  So instead of a one-gene one-product kind of model, we have a one-gene many products model and what we're trying to figure out is how this works.  So, what is the code within the genetic code that tells the cell how, when, under what conditions, et cetera to perform these splicing variants.

Chris -   So in a nerve cell, the same gene may do something completely different to a liver cell, but the big question is, how does it know it's a nerve cell or a liver cell and therefore to behave different?

Joseph -   Exactly.

Chris -   And how did you approach that?

Joseph -   Basically what we did is interdisciplinary research that we started off by doing experiments and that was done at the Blencowe lab and we measured around 4,000 pieces, called axons, of genetic messages across 27 different mouse tissues.  Then we analysed the data to figure out how these changes occur.  So, the different inclusion or exclusion of these bits and pieces of the messages in the different tissues, how does it change?  And then we went to the genome to figure out what is this code, what are the different components that determine these changes, so we can actually look at the genetic code and figure out if we just look at it, what would be the changes in say, brain versus liver as you suggested.

Chris -   So in other words, by looking at many thousands of genetic sequences and doing this lots and lots of times in lots of different tissues, you can begin to tie together how a different gene gets cut up in a different way in a specific tissue, and then you can begin to work out what sequences are hidden in the genetic material that's making that happen.

Joseph -   Exactly and that's the computer science part of the research - the machine learning part of the research.

Chris -   So presumably, this is really important because what this will enable us to now do is when we want to do gene therapy on something, up until now, we've taken a very simple approach and said, "This gene turns into this product in a cell regardless of what cell type it is."  So we just put the gene in and we'll get the product out.  It hasn't always been as successful as we would've liked.  Now, we're in a position to apply the discovery you've made which means that we can begin to ask, "Well, will this gene behave the way we think it will?"  So presumably, your model will enable us to make predictions so that we can work out how genes will behave in different tissues.

Joseph -   Exactly.  So once you have that program, that model, then you can look at areas that you've never seen before, you've never measured in the original experiments, and use the program to tell you what's going to happen.  You can also relate certain mutations to certain diseases, et cetera, and that's where a lot of the potential lies.

Chris -   We know that cancer, killing one person in three, is a genetic disease.  Does this mean that different cancers are going to behave differently in different tissues or that the genetics of cancer is going to differ between tissues because of what you found?

Joseph -  This is one of these promising directions that we're going to do follow up research - dedicated research.  So, instead of just looking at say, different tissues, we're going to look at different diseases and disease-versus-normal or subtypes of diseases, and as you've mentioned, different types of cancer et cetera, and concentrate on this.  In the study already published, we concentrated on certain neurological diseases and show the relation between the code that we found and mutations in certain areas.  So there's a lot of potential there definitely.

Chris -   And just to finish off, you've done this in mice.  Is what goes for a mouse, what goes for a person?  Do the same messages hidden in the genetic sequence that make the cells chop genes up this way in mice also work in men?

Joseph -   Right.  So that's an excellent question.  So first off, in the original paper, what we did when we analysed diseases, we analysed areas we know are conserved and we were able to relate the changes that we found using the mouse genome to diseases in the human.  But of course, the next step is of course to analyse more data coming from the human.  That's what actually we're doing now.  So, this is sort of work in progress.

Can we use chlorophyll as a source of energy?

Chris - Can chlorophyll actually be introduced into our bodies so that we could avoid hunger for example? So when you get peckish, rather than have to eat something, you just go and bask in the sunshine (assuming you don't live in Britain where there is no sun!)

Dave - I thought I'd start off with a physics approach to this to see whether it's at all practical. You've got about half a square metre of skin which you can point at the sun (you've got about a square metre in total, but you can only point half of it at the sun at any one time). The sun produces, at most if you're on the equator and on a really sunny day at midday, about a kilowatt of sunlight per square meter. It's probably about half that on average during the day and it's only day time half the time - so on average over 24 hours about 250 Watts. The maximum theoretical efficiency of photosynthesis is about 20%. But that's only compared to the half of the light it can absorb, so that's only about 10% efficiency. If you multiply those all up, you get about 12 Watts of power continuously throughout the day if your skin was completely saturated with chlorophyll, in practice the output would probably be far less than this. Now it sounds like that might be quite useful but the problem is that when you're just sitting in a chair, vegging, you use about 60 watts of power.

So, it might help a little bit, but no it certainly won't solve all your problems. I'm also guessing that the actual physiological issues would be quite serious. I guess Chris you're better to talk about those! Chris - Well some animals have done this to a great effect. There's the Sacoglossan sea slug which famously in recent years has been discovered to actually have chloroplasts - chlorophyll containing bodies - in its skin. This slug eats algae, marine microorganisms including sea weeds and things, and it has got this special system where it has tubes connecting the lining of its gut with its skin. When it eats the algae, it gets the chloroplasts with the chlorophyll in from the algae and puts them under its skin. Amazingly, the genome of the sea slug contains a number of additional genes from sea weed that can keep those chloroplasts alive. So this sea slug really does augment its metabolism using sunlight.

Presumably, your worry would be if you start putting chlorophyll into the body, would the immune system have something to say about it? The likelihood is, if you got it in there from birth, so you educated the immune system about it, I don't think there'd be a problem. Let's face it, if you're in a position to start turning people green, the likelihood is that you probably would've surmounted the immune problem too, I would guess!

Dave - I guess you'd need some quite serious genetic engineering to be able to add those genes into your body to be able to support the chloroplasts as well...

Why do some plants have purple leaves?

Dave - I had a go at this doing chromatography on chlorophyll on Kitchen Science a few weeks ago. Although most of the pigment in the plant is actually purple, if you actually do the chromatography, you do see there is still some green pigment in there, and so there is some green chlorophyll there in purple plants to do the photosyntesising, they just have other pigments as well which absorb green and yellow light to make them a deep purple colour. In things like algae and sea weeds, they canhave a different colour of chlorophyll, a completely different chlorophyll which absorbs blue light better than red light, because blue light travels through water a lot better than red light.

Chris - Yes, red light doesn't - that's why blood looks black under water because all the red light has been soaked up by the upper layers of water.

Dave - Yes.

Chris - And there's nothing to reflect off the red blood, so it looks black.

Dave - So red sea weeds have just got a different form of chlorophyll and I think that purple plants just have some green chlorophyll in there as well as a purple pigment which doesn't photosynthesise.

Why haven't scientists been able to create life in the lab?

Kat - In fact, they have. Craig Venter, the US Genome Sequencing bod, publisheda report in the journal Science a couple of years ago - they did actually completely build a very simple bacterium, Mycoplasma genitalium from scratch. They made all the DNA and they kind of put it all together. It was incredibly hard to do. The fact that we know the genome sequence of a lot of organisms and particularly simple organisms like viruses and bacteria is a far cry from actually making the DNA in exactly the right order, building that DNA strand and then putting the whole thing together. But I think Craig Venter's grand plan is to make artificial life. This is certainly a start and it has kind of been done. So, yes - it has been done, but it's very difficult.

Chris - But the cynics would say that he used a cell that had already been made and then put the genetic material in and it's that key thing is that membrane being made, it's the biochemistry that kick starts the DNA you put in into action which is the key recipe, the key ingredient in life that we just don't understand at the moment.

Kat - That's true and some people did say, "you've just stuck an instruction book into this bag of stuff!" I think building the rest of it is going to prove more tricky. The fact that we know what makes it up doesn't prove that we know how it's been put together. But obviously, the more we understand about how enzymes work, how organisms work, it might be possible. In terms of creating life from scratch, there were the famous experiments by Stanley Miller in the 1950s and '70s, mixing together a whole bunch of chemicals, zapping it with electricity and making things like simple amino acids. So those kind of experiments are being done as well. So, it may be that we will see completely artificial life appearing in the lab soon.

How and why do chameleons change colour?

It's nature's example of Joseph and his Technicolour Dream Coat, the chameleon. They're just phenomenal. There is this myth that chameleons change colour to blend in with their surroundings, but this is actually not true.

Most of the reason chameleons change colour is as a signal, a visual signal of mood and aggression, territory and mating behaviour.

The way that chameleons actually do this is molecular - they're molecular masterminds, really.

If you look at the skin of a chameleon, you find that they have several layers of specialised cells called chromatophores and these are cells that can change colour.

On the outer surface of the chameleon, the skin is transparent and just below that is the first layer of these cells, and they contain pigments. These cells are called xanthophores, containing particular specialised pigments that have a yellow colour.

Beneath that are pigment cells which are called erythrophores, which have a red colour in them.

Beneath them is another layer of cells called iridiphores, which have a blue coloured pigment called guanine; this is actually also used in making DNA.

Underneath all of those is another layer of cells called melanophores, which have a brown pigment - melanin - in them.

Now, how does the chameleon change colour? Well the chromatophores are wired up to the nervous system. They are also sensitive to chemicals that are washing around in the blood stream of the chameleon.

What happens is that the colours are locked away in tiny vesicles, little sacs inside the cells that keep them in one place, so the cells don't look coloured.

But, when a signal comes in from the nervous system or from the blood stream, the granules or vesicles can discharge, allowing the colour to spread out across the cell, and this alters the colour of the cell. It's rather like giving the cell a coat of paint.

By varying the relative amount of activity of the different chromatophores in different layers of the skin, it's like mixing different paints together. So if you mix red and yellow, you get orange for example, and this is how chameleons do this. They mix different contributions of these chromatophores.

It's a bit like on your television screen. When you mix different colours together on the screen to get the colour that the eye ultimately perceives and so, that's how the chameleon changes colour, and usually does so to convey mood.

So a calm chameleon is a pale greeny colour. When it gets angry, it might go bright yellow, and when it wants to mate, it basically turns on every possible colour it can which shows that it's in the mood. This is not unique to chameleons.

Other animals also have these chromatophores. Cuttlefish are another very elegant example of how this works.

For chameleons though, it's not so much to do with camouflage, it's more to do with communication...

Would you feel lightning strike a house?

Dave - Lightning is basically a huge spark. You get about 100,000 Amps of current flowing down through the air. This gives out about a thousand trillion Watts for about 30 millionths of a second, so the total amount of energy released is about 30 mega Joules of energy. That's very roughly similar to a 30-kilogram bomb.

Chris - It depends on what the bomb is made of, doesn't it?

Dave - Yes, but it's similar of order of magnitude. Quite a lot of that energy is going to be a long way up into the sky though. So basically, that energy is equivalent of about a kilogram of, say, TNT going off near your house. Most of that energy goes into heating up the air and it gets very, very hot. When hot air expands, that creates a shockwave of air pushing outwards and that's what you hear as a thunder. If that happens very, very close to you, then you will actually get quite a large overpressure, like a bomb going off, and if a bomb can shake your house, then a lightning strike should be able to.

Chris - I did some back of the envelope calculations. I think it's 120,000 pieces of toast you could make with the energy in one lightning bolt, assuming you could turn all of it into toast, obviously. So that's really quite a lot, isn't it?

Dave - For the time period, certainly, yes.

Why do birds fly into windows?

Kat - I think he's little bird brained! Now, birds do fly into windows. At home, my Mum has a lot of bird outlines stuck against the window to stop them flying into them. They fly into them for various reasons. Firstly, it's clear glass - they might not see it's there. They might think, "Ooh! That looks like a nice room, maybe a bit of floral wallpaper..." Bang! Straight into the window. So if you do have big patio doors, it's quite good to put stickers or something on them. The other thing is that the birds may be seeing their own reflection and, as it is the time of year when birds maybe get a little bit frisky, they start fighting with each other. Maybe it's a male bird, and it will start fighting with male birds or trying to mate with lady birds. So perhaps...

Chris - Surely they should mate with feathered birds because lady birds are insects and are a bit small for a bird to mate with, aren't they? Kat - Female birds. Thank you, Chris. So perhaps the bird is actually seeing its reflection in the glass and flying at it, trying to attack it and not realising that it's not another bird, it's its own reflection. Especially with houses normally if the room behind it is quite dark, that makes the window look even more reflective and then act more like a mirror. So I suspect that your bird is fighting some imaginary turf war with itself and that's why it keeps flying into your window. Try keeping the lights on in the room so that the room's not so dark or try getting a cat or putting something like stickers or something on the window might help.

Chris - Or a shotgun of course.

Kat - Or a shotgun. No! That would be nasty.

Does alcohol kill brain cells?

Chris - I can deal with the spicy one straight away because in fact, that's a myth and there's evidence that people who eat a lot of spicy food have lower rates of Alzheimer's disease than people who don't eat spicy food. This is because turmeric, the orange stuff which, when you get a bit drunk in the curry house and spill your curry down your shirt (which is always white for some reason when this happens), is the stuff that stains. Turmeric has actually got anti-inflammatory and anti-oxidant qualities. It seems to cut down the production in the brain of a chemical called beta amyloid and beta amyloid is the stuff that makes Alzheimer's disease happen. It builds up and forms plaques in the brain that damage nerve cells. So if you eat lots of turmeric, it seems to reduce the risk of that happening. So spicy food is good for your brain. That's that one done. Booze - booze is more difficult. The evidence is, if you were to incubate nerve cells in a solution of alcohol, they would die. So alcohol is a toxin. Thankfully, the body is really well set up to deal with it metabolically. The liver handles alcohol extremely well and only a tiny proportion of the alcohol we drink actually gets into circulation because the liver sees all of the blood that comes from the digestive tract before it goes anywhere near the rest of your body, and the liver therefore deals with the booze before it goes systemically around your body and into your brain. But a small amount of alcohol does go into the brain and when it gets there, the reason it makes us behave the way it does - and we all know what the effects are - at least in modest doses, is that alcohol increases the activity of one of the brain's inhibitory nerve transmitter chemicals. This is called GABA. This damps down the activity of nerve cells. So unlike certain drugs like ecstasy which can in fact make nerve cells more active and damage them, alcohol damps down the activity of nerve cells and therefore it makes them less vulnerable to damage. Jennifer - So they might live longer?

Chris - Well, they may do. The evidence is, small doses of alcohol probably don't harm neurons and the body's pretty well set up to cope with it anyway. If you look at people who have spent their whole life drinking modest amounts of alcohol, there's evidence that actually their intellect may be preserved better than teetotalers. That's not saying, now, prescribe yourself daily alcohol intake to live a long time and have good brain function into old age. That's not what we're saying. But what we are saying is that epidemiologically, if you look at populations, the evidence is that it doesn't do any harm. There's no evidence for significant harm in those people. If you also look at people who are chronic alcoholics, unless they get a condition called Wernicke-Korsakoff's psychosis - which is where they run out of a vitamin called B1 (thiamine) which is very destructive to nerve cells - they don't actually have huge damage to the nervous system unless they are very, very, very heavy drinkers for a very long time. So therefore, the evidence is that alcohol is probably okay in modest doses and most of the injuries and most of the damage to the brain happens when people get drunk and fall over and hit their head, or get into fights. That's actually the reason why head injuries happen with alcohol and why brain damage probably occurs.

38:22 - Grand Designs Live - Greener Technology for your home

Meera explored Grand Designs Live at London's Excel centre to find greener ways to fill your home with gadgets...

Grand Designs Live - Greener Technology for your home
with Kevin McCloud, Anthony Goody, Brit O'Sullivan

Chris -   Now, it's time to join Meera Senthilingam for a bit of a technology update because this month, she has been at the Grand Designs Live Show.  This is a London based exhibition which is inspired by the television program of the same name, and it celebrates innovation in architecture, and Meera's been along to find out a bit more...

Meera -   This week, the Grand Designs Live Show has been taking place at the Excel Centre in London.  There are over 500 exhibitors and displays, showcasing ways to design, improve and power your home.  There's a whole host of technology and gadgets on display so I've come along to see what's on offer.  Now I'm here with the man behind Grand Designs Live, Kevin McCloud.  Now Kevin, what's Grand Designs Live all about?

Corrugated cardboardKevin -   In a sense I suppose it's about bringing the television shows to life.  So it's about giving people the experience at an exhibition which is rich and exciting, and educational.  What we can do is show people all the stuff that goes into buildings and what makes them tick and work, and give them a good time.  There's a lot of seminars and events for them to take part in.

Meera -   What are the key themes about this year's show in terms of house design?

Kevin -   Year-on-year, we try and steer it more and more in the direction of sustainability.  We now have a full green audit of every single exhibitor and of the whole show.  [In the Kevin's Green Heroes section] there are ten products which represent different aspects of construction and design, from furniture through to insulation and carpet which are little known.  And there are some really fun things here as well.

Meera -   There's a great variety actually.  So there are recycled clothes pegs, there's a wonderful wardrobe over there made of cardboard.

Kevin -   Yeah.

Meera -   Which actually looks quite sturdy.

Kevin -   Yeah that's Giles Miller.  He's cardboard king.  He makes beautiful cardboard, and beautiful cardboard lampshades too. And the eco-force clothes pegs!  I put them in because somebody said to me, "you know clothes pegs, there's a company that make them out of recycled plastic."  I said, "Yes."  Well surely, all clothes pegs are made out of recycled plastic and I thought, we just have to put them in just to make the point really. 

And we're standing on this - look I have to show you - this is amazing stuff.  This is carpet we're standing on.  They're carpet tiles, about 12 inches square.  They're brown and black and gray.  I think they look quite glamorous and they're very durable and hard wearing, and I've got one here.  Each carpet is just a backing and on it, the strips are 12 inches long and it's just a piece of car tyre.  It's just a piece of car tyre that they then brush to bring out the pile of the fibres that were inside the tire.  This is a minimally processed product.  It's made from tyres and it looks beautiful and glamorous.  I love that.  The problem is at the moment about 7 percent of tyres are recycled and we throw 486,000 tons of old tires away every year in this country.  We can't put them in landfill anymore, you can't even put the rubber crumb in landfills, so we need to think about what we're going to do with the stuff, and we should think about doing that in a way which minimally processes them.  I put this in because it just ticks all those boxes.  It's an amazing product.

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Meera -   With me now is Anthony Goody who's a technology expert for Media Tech.  We're inside the Phillips House of the Future and so, what exactly will the house of the future be about?

Anthony -   The house of the future will be adopting some different themes of how we move forward of all our future technology. Our main one is energy conscious living.  So it's how we reduce the impact our homes have on the environment in the future, from everything from reducing our water consumption to reducing our energy consumption.  Switching to LED lighting for instance could actually reduce power consumption at home by up to 90% when compared to standard light bulbs in the home.

Meera -   Now we're inside the House of the Future.  It's very white.  It's very bright and there's very cool looking gadgets all over the place.  So you've mentioned LEDs already which lots of gadgets and lighting around here seem to be made of, but what are the other new gadgets that are on show here?

Anthony -   One of the key products on the show at the House of the Future this year is actually our wireless power technology and this is essentially the ability to deliver power over a distance.  So it's time to cut the cord and to remove our cables from our laptops, and our phone chargers.  So essentially in the future, you'll be able to enter the house of the future, your mobile phone will instantly start charging and you'll never have to plug your laptop in again to get it charged. All of your devices, gadgetry will all be powered wirelessly.

Meera -   So at the moment, it requires localised hot spots, doesn't it?

Anthony -   That's correct, yeah.  We got localised hot spots that deliver energy power transfer around the distance of 20 centimetres, so you could have a special place on your coffee table in the lounge that charges your laptop or a special place in your kitchen that you could have to power your blender per se.  But in the future, they've actually got trials going on in America at the minute, that are delivering power in a distance of up to 3 metres.  So essentially, you can vacuum cordlessly.

Meera -   So I guess lastly, how would you summarise the house then?  It looks very pretty.  It looks very futuristic.  Is this going to be your home of the future, do you think?

Anthony -   This is definitely my ideal living scenario of the future.  This is what my home would definitely be like.  We've absolutely got everything on display here.  Obviously, we're heading this up with wireless power.  All of the devices as well are connected so all of our lighting is controlled by one central remote controlled unit.  It's just all about usability and easability of living in the future.  And of course, a smell reducing toilet just to top it off!

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Meera -   Staying on the eco theme, I'm now in a home, a very comfortable home out on a roof terrace, but surprisingly, this house is made out of shipping containers.  And with me, to tell me a little bit more about this is Brit O'Sullivan who works with the company making these which is Eco-Modular Living.

Brit -   We brought with us to Grand Designs a two-bed one-bath home on two floors which is made of four shipping containers, two on top of each other.  The house is made out of standard shipping containers.  It takes 21 days from them looking like ordinary second-hand shipping containers to being turned into a home which includes carpets, recycled plaster-board walls, a kitchen, a bathroom, with all the doors, and fixtures and fittings.

Meera -   What are the main reasons for people to go for this kind of home?  What are the environmental benefits of it?

Brit -   It is very environmentally friendly.  We're using a recycled product already.  You Eco Modular Livingcan bolt on as many sustainable credentials as you like, so you can have a living roof, solar panels attached.  It's currently signed off as code 4 of the sustainability code, but if it's actually sat within the right environment, it would reach zero carbon.

Meera -   What's the market for these?  So who are you trying to attract?

Brit -   Our client base is quite diverse.  So if you think both public and private sector, we've got individuals who want to do a self-build.  Also, we are very popular at the moment with councils.  We're actually presenting and designing for various councils across the UK for affordable housing.

Meera -   I'm very comfortable out here on the terrace and I'm not yet a homeowner, so what's the retail price of this?

Brit -   This one at the moment is 95,000 which gives you two containers on the ground floor, giving you a kitchen, dining, and living area.  And then on the first floor, it gives you two bedrooms and a bathroom.  Just get your land and then we'll be there within 21 days.

Kat -   Absolutely fantastic stuff of the future.  I for one will be first in the line for the smell free toilet, living with three boys.  Anyway, that was Brit O'Sullivan from Eco Modular Living and before that you heard Anthony Goody from Media Tech, and Kevin McCloud from Grand Designs, taking Meera through the latest futuristic and environmentally friendly technology for the home.

How can hair change colour along its length and why does it change colour with age?

Your hair is coloured because you have cells that pump pigment into the hair as it's growing. As you get older, these pigment cells basically get a bit knackered and they stop putting colour into your hair - which is why your hair goes grey. It doesn't actually go grey, in fact, it goes colourless. It goes white, but against the background of darker hair, it may look gray. This is because the pigment has stopped being pumped into the hair.

Also, pigment cells don't continually pump pigment into the hair. They may take little breaks, going in a cyclical way, and so it's perfectly possible for hairs to be different colours along their lengths. It's probably unusual that you'd have zebra print hair, but it is certainly possible that they might stop producing pigment for a bit and then start producing pigment again.

Why do we cry?

It's obviously a very highly evolved behaviour because we are the only animals that do it. Other animals, although this is possibly disputed by some scientists, don't appear to cry. It's thought that you cry in response to a stimulus, some scientists thought it might be to do with the build up of stress and hormones - a hormone called adrenocorticotropic hormone might actually be released through the tears. So when you're in a stressful or unhappy situation, you actually release this hormone and get it out of your body through your tears. There is evidence for certain hormones found in your tears, things like the hormone prolactin, other things like potassium and manganese. And so, tears produced when you're crying for emotional reasons actually have more of these things in than tears that are just lubricating your eyelids. So perhaps, you might be able to tell if someone is just faking it or just the got onions out by measuring these hormones in their tears. Interestingly, another thing about crying, women do cry more than men. It's thought to be to do with certain hormones that are only found in women. As studies showed on average that men cry about once a month, women cry about five times a month on average. (More around the time of the month ladies.)

The other interesting thing about crying is that it may well have evolved as a communication signal to say, "I'm really unhappy and I need a cuddle" or "I'm really upset. I'm really angry. I'm really stressed." Because obviously, people can see your tears and respond to them, so it may well be some kind of signal - showing that you're vulnerable, that you're unhappy - that other people can respond to.

Is there a cure for spots?

If you look at skin and if you look closely, you'll see that on the surface of the skin there are lots of little tiny pits or holes. Those are pores. These are tiny little glands, or the openings of little glands from glandular tissue which is deeper in the skin. That glandular tissue produces various chemicals, mainly oil based ones including sebum which oozes out from the gland and nourishes the overlying skin and also controls the chemical environment of the overlying skin. It controls, for instance, the growth and proliferation of various microorganisms.

The thing is, these glands are very sensitive to androgens, testosterone-like chemicals in the blood stream. When a person goes into puberty, the time when the secondary sexual characteristics form, the levels of testosterone in both girls and boys increase enormously. This makes the gland tissue in the skin dramatically increase its productivity of these oily chemicals and as a result, the skin becomes a lot greasier which can affect the proliferation of certain micro-organisms. Certain microbes survive better under those conditions and it also means that it's more likely that the little ducts that drain those glands can become obstructed, either by the oil itself or other things applied to the skin like creams, lotions or just dirt and grime.If they become obstructed because they're producing much more material, then bacteria, which can get into them, can overgrow within the blocked gland and the overgrowth of the bacteria can then trigger inflammation. When you have inflammation, the immune system comes in and attacks the bacteria, and in the process it produces inflammatory chemicals that open up blood vessels, they wind up nerve cells and they also attract other components of the immune system which makes the area get red, hot, swollen and tender.As the micro-organisms are attacked by the immune system, the white blood cells that come in to do that can also die in the process. This is what produces pus, or the yellow stuff you get inside a spot. It's a good idea not to squeeze a spot, because although sometimes the stuff can come out in the right way, what can happen is instead of splurging out the front, the pus-y inflammatory debris inside the spot can sometimes go sideways into the adjacent skin tissue. This spreads the infection and also increases the degree of inflammation and this in turn can damage the underlying skin tissue which can produce more swelling and if it's very bad you can get scarring.

Some people are more prone to spots than others. Probably because some aspects of their genetic make up might mean that they have certain populatons of bacteria on their skin that are more likely to provoke spots. It may be that they're more sensitive to testosterone and androgens and this makes their glands produce more of this oily material in the first place. Both of those in combination can conspire to make some people more prone to acne and spots and they way they react to those bacteria with inflammation for example.

So the long and the short of it is that unfortunately it's a consequence of growing up. As you get older, the amount of testosterone being produced in surges drops a bit and therefore the skin acclimatises and becomes less greasy.

But for people for whom it's a big problem, you don't have to suffer in silence because there are some good treatments. In people who have chronic cases, antibiotics are very effective. Members of the tetracycline family of antibiotics are very good and taken for about 6 months, they can sometimes eliminate the bacteria that are causing the problem and prevent any more skin damage. This means the skin then has a chance to recover. If it does recur you can simply start the antibiotics again.Obviously antibiotics are dramatic measure and so you should try and use simple measures first. Soap and water to get rid of the excess oil and then things like benzoyl peroxide creams which can help to take off the excess skin and stop the ducts from getting blocked in the first place. But it is a big problem, luckily it does tend to improve with age.

57:56 - Why haven't crocodiles changed?

Why have crocodiles remained the same while other species have evolved? What's so special about croc genes?

Why haven't crocodiles changed?

We put this to Michael Benton, Professor of Vertebrate Palaeontology at the University of Bristol:

Michael - Crocodiles are extraordinary animals. They are not very common. There's only about 15 species of them on the earth today and they haven't really changed very much for the last 200 million years, or at least to our eyes, they haven't.

There are two reasons that people sometimes give to try and explain this phenomenon. We call them living fossils, meaning, animals or plants that haven't apparently changed very much. It's not a very precise term so we have to be very cautious about it. It may just be our perception - they look the same to us. But those explanations are either that they're hugely successful on the one hand or on the other hand, that they're just doing something that nothing else wants to do - so a kind of strongly positive and a somewhat negative interpretation.

So, the highly successful argument is that crocodiles are doing something remarkably well. They're preying on animals, fish and land animals in fresh water generally, sometimes in salt water. They're feeding in a particularly beastly manner and nothing else can compete, and they do it so well that there's no reason for them to change their mode of behaviour.

The other explanation is that they're doing something so obscure that perhaps no other animal is interested or has had any evolutionary pressure that it should evolve into this particular niche, and therefore, nothing is really competing with crocodiles, so they can just potter on doing what they've been doing for the last 200 million years, and nothing in evolution is driving them to change.

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