Growing human hearts

Growing a human heart from a single cell may seem like science fiction, but scientists at the Gladstone Institute at the University of California San Francisco, have taken a huge step forward, by producing the first three-dimensional, beating, human heart chamber. Previously, it had been possible to produce a two dimensional sheet of beating heart cells, but to really gain an understanding of heart formation in a developing foetus and perhaps more importantly, how drugs given to women during pregnancy may affect this development, a three dimensional structure was needed. By treating stem cells with drugs and then confining them to a very small spherical geometry, Bruce Conklin and his team have managed to grow their very own three dimensional model of a human heart, as he explains…

Bruce – the cells around the edge became fibroblasts – a particular type of cell that you use to heal wounds and then only in the very centre were cardiac cells that beat. What this is forming is more of a little organoid is what we call it, where there’s beating cells but there’s also multiple other cell types and that’s what makes it so interesting is that these cell types are somehow talking to each other and somehow collaborating in some way so that they can actually make this structure that we didn’t expect.

Tom – It’s almost like they’re trying to form a heart…

Bruce – That certainly is the impression. They’re heart cells, they’re forming cavities so it could be a model of how parts of human development occurs, but it certainly is not a real human heart in the sense that there’s probably many things that we’re missing. We just have a simplified version with just one chamber, but having it in a controlled way where it happens the same way over and over again we can start asking questions about ‘how do these cells talk to each other?’ So once you have a system which is reproducible you can do experiments to break it in some way or to enhance it in another way.

Tom – What are the applications of this work then?

Bruce – The most obvious application of the work is to study human development. How do cells actually form a heart is something of basic interest. And also, the most common form of birth defects is actually cardiac defects. But the other application is that we can expose these developing human micro-chambers to drugs which are thought to cause developmental defects, specifically of the heart, and in fact one of the key experiments in this study was to use the drug thalidomide which is notorious for causing birth defects. When we expose these cells to the thalidomide they had a dramatic change in the morphology so that you could see that it was altering the developmental process in this micro-chamber. Thalidomide was tested in rodents before it was tried in people and there were no cardiac defects in the rodents. I think that more and more we’re thinking how do we get tests which use real human cells so that we can actually make safer drugs. And in this case say you turn back the hands of time and you had this sort of test perhaps you would have discovered that thalidomide was dangerous before it had gone on to be given to people.

You can listen to the full interview with the Naked Scientists here.

Can you pee on the moon?

Question

If, in some miraculous way, one were able to pee standing on the surface of the Moon, what kind of arc would it create?

Answer

Dr Chris Messenger from the University of Glasgow was on hand to help me with Michael’s question…

  • The moon’s gravity is 16% of that on Earth, which means the pee will travel in a straighter arc and about 2.5 times further
  • In a uniform gravitational field objects travel in a parabolic arc – sort of a ‘u-shape’
  • On the moon, the atmosphere is so thin that the pee would follow a very accurate parabola, as can be seen with the dust thrown up by the lunar rover
  • The low atmospheric pressure on the moon would immediately boil the pee which would then fall to the surface as steam
  • Despite the low temperature of the moon (as low as -170 degrees Celsius), the pressure reduces the boiling point of water so dramatically that your pee would boil way below body temperature of 37 degrees Celsius, which is why it immediately turns to steam
  • The freezing temperature of water on the moon also occurs in the same range as the boiling point, which means that the steam molecules will then freeze into yellow ice crystals

You can listen to the full version of Question of the Week with the Naked Scientists here.

Can ants feel pain?

Question

Carol asks: Can ants feel pain?

Answer

I went crawling around for the answer with York University’s Eleanor Drinkwater…

  • Ants can sense that they’ve been harmed and react but this is different to actually feeling pain
  • Nociception is the sensory nervous system informing the brain that you’ve been hurt, whereas pain is an unpleasant sensation with a negative emotional response
  • One can occur without the other eg. when playing sports you often don’t realise that you are injured until afterwards, or people who have lost limbs experience phantom limb pain
  • Robots can also be programmed to experience nociception without experiencing pain, for example in the video game The Sims characters will jump around if they’re burnt by fire
  • We currently know very little about insect expressions of pain, but we do know that the pain expression systems are different to those in mammals, meaning that insects are likely to experience pain in a different way to humans
  • In short, the jury is still out, so best to be nice to any ants that you may come across!

Part of the Naked Scientists Question of the Week series – you can listen to the full version here.

Do roast potatoes give you cancer?

The UK Foods Standard Agency issued a health warning in 2017 about the chemical acrylamide – found in starchy foods such as bread and potatoes – saying that it may cause cancer. The warning coincides with the launch of a new health initiative called ‘go for gold’ which encourages us to only cook foods to a golden yellow, rather than brown or black, to help to reduce the amount of acrylamide. I spoke to Jasmine Just at Cancer Research UK…

  • Acrylamide is produced naturally by starchy foods when they are cooked at high temperatures for a long period of time, such as when baked, fried, roasted or toasted.
  • It is created by the Maillard reaction that occurs between sugars and amino acids in the presence of water, which is also responsible for the brown colour and roasted taste.
  •  A number of animal studies have found that acrylamide has the potential to damage our DNA which can lead to cancer, but the same process has yet to be established in humans.
  • The risk is described as ‘probable’ but is certainly much less than that from smoking, obesity and alcohol.
  • The advice from Cancer Research UK is to maintain a healthy balanced diet, follow the cooking recommendations for baked or roasted goods, and to not store potatoes in the fridge as this increases the potential for acrylamide to develop when they are cooked.

You can listen to the full interview for the Naked Scientists here.

Cocaine addiction leads to iron build-up in the brain

Cocaine used to be the drug of the rich and famous, but over recent years it has become cheaper and more readily available, and as a result more and more people are becoming addicted to this highly dangerous substance. A report last year from the UK Government Advisory Council found that 1 in 10 people between the ages of 16 and 59 had used the drug at some point. The current treatment for cocaine addicts is through therapy, but relapse rates remain high. Now a new study has linked cocaine addiction with a build up of iron in certain parts of the brain, and particularly areas known to control our inhibitions, although the team don’t yet know what the iron is doing there. I spoke with lead author Dr Karen Ersche…

  • Cocaine addiction leads to disruptions in the regulation of iron, with reduced levels in the blood and higher levels in the brain
  • Iron build-up in the brain is highly toxic and can be seen in other degenerative diseases such as dementia and Parkinson’s
  • Participants in the study had a brain scan which identified iron build-up in the area of the brain that controls inhibition
  • Possible explanations are that cocaine users have an appetite for fatty foods which hampers the absorption of iron, or that the cocaine weakens or destroys the blood-brain barrier causing iron to leak into the brain
  • The study also found a relationship between the amount of iron accumulation and the duration of cocaine use, but further work is needed to clarify its effect on brain cells
  • Understanding the relationship between cocaine addiction and iron regulation in the body could provide a new avenue for treatment in the future

You can listen to the full interview for the Naked Scientists here.

The World’s Smallest Knot

What do a clove hitch, a sheet bend and a sheepshank all have in common? They are of course, as any former scout will tell you, all knots. But I bet they couldn’t tie an 819 knot: at less than a millionth of a millimetre across, it’s the world’s smallest knot and has been tied by a team at the University of Manchester. They made the molecular tangle in a test tube using a sequence of carefully-controlled chemical reactions that used iron catalysts to bend and entwine short strings of carbon-rich molecules. I heard how from lead author David Leigh…

  • The knot is 192 atoms long with eight crossings and is the smallest, tightest knot ever tied.
  • The width of the knot is half a nanometre – less than one millionth of a millimetre or ten thousand times thinner than a human hair.
  • In mathematics, a knot describes a closed loop, which means that the knot here with its ends fused together, is still by definition a knot.
  • By viewing the positions of the atoms using X-ray crystallography, the knot can be seen to look like a four-leaf clover with extra strands wrapping around the outside of the leaves to generate the 8 crossings.
  • The knot is made using the technique of self-assembly where molecular strands are woven around metal ions, not too dissimilar to knitting.
  • The new technique used to make the knot could lead to a method of weaving molecular strands together to form stronger, lighter and more flexible materials.
  • In particular, Kevlar vest could be made much stronger by weaving the ‘rods’ of material together, rather than having them packed closely together like pencils in a pencil box, as is currently the case.

You can listen to the full interview for the Naked Scientists here.

Music Taste Linked to Brain Type

How does the way you think influence the music you choose to listen to? Scientists at Cambridge University have developed a test that marries up a person’s personality traits including how empathic they are, and how systematically they think, with the tunes most likely to resonate with them. I went to see the lead researcher David Greenberg to discover what the test revealed about my own musical tastes…

David – The measure of empathy is called the empathy quotient and it’s a sixty-item measure that asks about how you interact in your daily life and your care for others, how you perceive emotion and react to emotion and thoughts of others. Another dimension is called systemising and systemising is the drive to construct, analyse and look at the rules that govern different aspects of the world.

Tom on the empathy quotient you scored a 56, and the average male scores around 30 so you were slightly above average on empathising. On systemising you scored very high – so you’re score is a 95 and the average male usually scores a 68.

Tom – Okay so that makes sense I guess – I do maths, I do see patterns in things and so this is sort of reflecting how I would have thought my brain worked.

David – It’s not too surprising because previous research has shown that males tend to score higher than females on systemising. And mathematicians score higher on systemising than for example students who are studying humanities.

Tom – And then once you’ve worked out how someone thinks, how did you then try to find out their musical preferences – do you say to them perhaps ‘here’s a list of band names who’d you like’?

David – No, so that’s been done previously where participants would just list how much they like a genre, but the problem with genres is that they’re so vast. If you take the rock genre in general, you have heavy metal, punk and you have bands like Metallica. But also in the rock genre you have Jeff Buckley or Jodie Mitchell and so there’s a vast difference. So we thought a more accurate way of doing it could be to just administer pieces of music to the participants: have them listen and then to indicate how much they liked each piece of music.

Tom – And so what did you find then? Once these participants have done this questionnaire you’ve worked out how they think – how did this affect their music choices?

David – What we found quite consistently over several studies was that empathisers in terms of the style of music that they liked, they were preferring music that was mellow and was from R&B, adult contemporary and soft rock genres. Whereas, systemisers were preferring music that was more intense and that was from the punk and heavy metal genres.

Tom – So what do I like? What did you find out about me?

David – You scored for example with mellow music or unpretentious styles which is from the folk genres or music that’s from classical or jazz, you scored average on those preference dimensions. But you scored the highest on intense music – so musical extracts that were from the punk, heavy metal and hard rock genres those were your favourites by far.

[MUSIC]

Tom – That was my favourite one that I listened to yesterday! I feel like I’ve been the perfect test student here! We’ve just been discussing exactly what type of music a systemiser should like and we’re just looking at my results here and I’ve nailed it to be honest!

And are there any applications for this beyond just figuring out which music people should and shouldn’t like?

David – A lot of research and there’s volumes of it has shown that music can be effective in music therapies. So, for example in terms of social skills or emotion recognition, we could use these results as a way of say teaching emotion recognition to children through music.

Tom – Based on my test results, play me the song that I should absolutely hate – I should leave the room I should dislike it that much!

[MUSIC]

…Yeah not liking that! That’s just so depressing I’m just not buying it.

David – But that’s the great thing about this study: there’s really no right or wrong answer. It’s just that people like different things and you can actually say that music is a mirror of the self in a way, it’s a reflective of who we are. And that our musical choices are a link or an expression of our mind, our personalities and the way we interact with the world.

You can listen to the full interview with the Naked Scientists here.

Looking inside your heart

One of the tools available to doctors to see the heart in action is the echocardiogram. This uses ultrasound waves to image the heart as it beats, so the cardiologist can tell whether it’s contracting correctly and that the heart muscle is a healthy shape. I volunteered to be a guinea pig…

Clare – I’m Clare Ward-Jones; I work for Phillips Healthcare and my role is a cardiac ultrasound applications specialist. We’ve got a machine the ETHIC and that is the supreme ultrasound machine for cardiology. We can do a 2D scan on you, we can also do 3D images so we can get a 3D model of the heart.

  • The machine is the same as that used for a scan on a pregnant woman and relies on ultrasound beams which are sent out from the end of the probe and bounce back when they hit structures in the body.
  • Patients must lie on their left-hand side to bring their heart closer to the front of the chest meaning the ultrasound has to travel a shorter distance and therefore produces a clearer image on screen.
  • Electrodes are also applied to the patient to monitor the heart rate during the procedure – mine measured 87 which lies between the normal rate of 60-100 beats per minute.
  • Jelly is applied to the skin to remove any air between the probe and the skin which ultrasound cannot travel through.

Rick – My name is Rick Steeds; I’m a consultant cardiologist. I’m particularly interested in cardiovascular imaging and I’m the current President of the British Society of Echocardiography.

  • Echo sounds are very good at showing the structure of the heart; how strong the muscle is; whether the valves work; whether they leak or whether they’re narrowed, and whether there’s damage to the heart, for example, from a heart attack.
  • The images of my heart show two of the four chambers and the valves between them opening and closing.

You can listen to the full interview for the Naked Scientists here.

The Naked Science of a DNA test

I had my genes sequenced by 23andMe in the name of science… and of course I had to ask about the ‘maths’ behind the results.

Nowadays, a lot of companies offer online ancestry tests, or tests to quantify your risk of inheriting some life-changing diseases. But how seriously should we take their results? Izzie Clarke and Tom Crawford spoke to Garrett Hellenthal from UCL and Julianna Cintron from 23andMe in order to find out…

Tom – Fill the tube with saliva to the black wavy line… shall we just crack on?

Izzie – Okay! You get the idea. But in order for companies to analyse our genetic information, all we have to do is spit into a test tube and send it off to the lab. Tom sent his to a company called 23&Me to find out about his health and physical traits, and I wanted to explore my family history. So, how does a bit of my saliva reveal so much about my ancestry?

Garrett Hellenthal from University College London’s Genetics Institute…

  • Saliva contains your genetic code in a series of cells which can be extracted and identified via a series of genetic markers that define your unique DNA sequence.
  • They look at about 500,000 different pieces of genetic code and compare them to the codes of people in the company database to determine who you share matching DNA patterns with.
  • Izzie found out that she is 30% Irish, 24% Western European, 15% Great Britain and 15% Scandinavian.

Izzie – But what about health and physical appearance? Let’s take a look at Tom’s results…

Tom – I think most of them are correct for me like I should likely have lighter eyes, and I have blue eyes. It says likely little upper back hair, and I can fortunately report I have minimal upper back hair. I was also pleased to see that I’m likely not to have a bald spot; I really hope that one’s true.

Izzie – In addition to appearance, Tom’s test was able to look at specific parts of his genetic code and explain the likelihood of there being a change called a ‘variant’, which could possibly lead to a life-changing illness.

Julianna – My name is Julianna Cintron and I’m a produce specialist on the customer care team at 23andMe.

  • There are some traits that are more influenced by genes than others, for example if you have two copies of the gene associated with having red hair then you are much more likely to have red hair.

Tom – Just with you mentioning there this idea of it’s to do with the confidence in something, or there’s a probability. We’re using phrases like more likely, it’s not sort of fixed. In my result I was told that I have a particular variant which leads me to be at a higher risk of Alzheimer’s disease and I was just wondering what exactly does this mean? Does this mean I will get Alzheimer’s; does this just mean I’m above average likely; how does this result actually relate to the risk factor?

  • The e4 variant is known to impact your risk of developing Alzheimer’s and having one copy of the variant puts you at a slightly increased risk of developing Alzheimer’s by a certain age. Having two copies increases the risk further.
  • Most of the genetic risks are actually relatively small, much less than say smoking or unhealthy lifestyles in general.
  • The most important thing is to use the results as ‘one piece of the puzzle’ and not as a diagnosis that you will or will not get a certain disease.

You can listen to the full interview with the Naked Scientists here.

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