Podcast: Barnard’s Star, and clinical trials

Host: Benjamin Thompson

Welcome back to the Nature Podcast. This week, we’ll find out about a potential exoplanet orbiting one of our nearest celestial neighbours.

Host: Noah Baker

And following the impacts of social media on clinical trials. I’m Noah Baker.

Host: Benjamin Thompson

And I’m Benjamin Thompson.

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Interviewer: Benjamin Thompson

For our first story today listeners, we’re going to travel into space for several trillion kilometres, or about six light years. This is the distance to Barnard’s star, one of the closest stars to our Sun after the Alpha Centauri system. Barnard’s star is a red dwarf and is relatively cool and small. It’s about a sixth of the mass of our Sun. Due to its close proximity, astronomers have spent decades searching Barnard’s star for evidence of orbiting exoplanets. There were claims in the 60s that a planet had been discovered, but these were later disproven and other searches have so far drawn a blank. However, things might be about to change, as a group of researchers have combed through a huge amount of previous data and think they might have found evidence that an exoplanet is there after all. Now, you might think that searching for an exoplanet would be easy – just point a telescope at a star and have a look. According to Ignasi Ribas, who led the new research, it’s not that simple.

Interviewee: Ignasi Ribas

Yeah, wouldn’t it be nice to have a digital camera take a telescope and take a picture and then see a nice planetary system orbiting a star, right? This would be our dream, and this dream is what we call direct detection of exoplanets.

Interviewer: Benjamin Thompson

Ignasi, who is based at the Spanish Research Council and the Institute of Space Sciences of Catalonia, hasn’t fulfilled this particular dream quite yet. In fact, direct detection is often pretty difficult for a number of reasons, so astronomers use indirect detection methods instead, looking for the effects that an exoplanet is having on its star. One of these indirect detection methods is known as radial velocity, and this is what Ignasi and his colleagues have used in their latest work. Radial velocity looks at a star’s slight wobble as it is tugged by an orbiting exoplanet. Now, you can’t see the actual movement of this wobble from Earth but as the star moves towards or away from us, you can detect a tiny, repeating shift in the frequency of its light, which we can see as its colour. This frequency shift indicates the size and period of the wobble.

Interviewee: Ignasi Ribas

That’s an indirect indication that indeed there’s an orbiting object around that star and then from this wobble we can actually calculate how massive is the object that is responsible for this wobble, and this technique has been used for ages.

Interviewer: Benjamin Thompson

Ignasi combined hundreds of radial-velocity measurements of Barnard’s star, collected by different groups over the past 20 years. Within these combined data, he and his colleagues identified a low-amplitude signal that repeated every 233 days.

Interviewee: Ignasi Ribas

And this tells that there could be a potential planet there with really low mass because the wobble is really small, and with a period that’s quite long. It’s comparable to the year of our year actually. We’re talking about 233 days – that’s really long compared to most of the other planets that people have observed. And by collecting all this huge amount of data, we have managed to see this signal very strong in the data actually.

Interviewer: Benjamin Thompson

The team reckon that the exoplanet’s distance to Barnard’s star is a bit less than half the distance of Earth to the Sun. They also suggest its mass is a minimum of 3.2 Earth masses. This puts the exoplanet in the super-Earth category. Now, sadly this doesn’t mean that it’s home to superheroes, but it does mean that it’s between 1 and 10 Earth masses. Other than that, we don’t really know much more about it.

Interviewee: Ignasi Ribas

The sad thing about finding planets with radial velocity is that we know very little about the planets actually. To tell you the real honest answer, is that we know how long its year lasts and we know what the minimum mass is. Everything else we have to calculate or speculate.

Interviewer: Benjamin Thompson

So, too early to talk about the exoplanet’s terrain or the inevitable discussion about its chances of harbouring life. In fact, perhaps it’s too early to talk about a lot of things. Is there really a planet there at all? After all, when it comes to Barnard’s star and exoplanets, astronomers have been wrong before. Rodrigo Diaz from the Institute of Astronomy and Space Physics in Buenos Aires, Argentina, has written a News and Views article about this new work. He says that when looking for exoplanets using radial velocity, there are a few pitfalls to be aware of.

Interviewee: Rodrigo Díaz

You have to be sure that the activity of the star is not tricking you because stars are not just balls of light emitting light uniformly, but they have their own activity and they have their own variations, and some of this can actually mimic velocity variations. So, you can confuse activity of the star, usually related to the magnetic fields of the star and the rotational rate of the star, with an actual planetary signal.

Interviewer: Benjamin Thompson

Rodrigo said that the amount of data analysed in this new research was impressive, and there’s reason to be optimistic that there is an exoplanet orbiting Barnard’s star. However, he noted that there’s still a chance that this could be a false positive.

Interviewee: Rodrigo Díaz

As the authors know perfectly well, this is a very tough thing to detect, so to test the robustness of the detection they used different methods to account for the fact that the star is active and that the star has its own intrinsic variability. So, one of these methods came out with a kind of worrying result that the signal that they see could actually be produced by the star. But it’s one method in a few, but then again you know that when you’re doing this kind of reasoning, the reasoning is as strong as your weakest link, so if there’s a weak link in the chain then we have to take the result with caution.

Interviewer: Benjamin Thompson

Ignasi told me that he’s 99% confident that an exoplanet is present, but he says there’s still work to be done.

Interviewee: Rodrigo Díaz

We have to keep gathering more data to make the case even stronger, and this 99% go to 99.9%, to 99.999% if we can, right? So, we’re trying to nail this and to make sure we investigate the star deeply enough to make sure this activity that all stars have is not the culprit of this signal that we see.

Interviewer: Benjamin Thompson

Both Ignasi and Rodrigo hope that in future, other detection methods and things like the soon-to-be-launched Gaia space observatory could confirm the presence of the exoplanet and tell us about its composition and atmosphere. There is so much to learn about how super-Earth-sized planets form, so this one – a mere hop, step and a jump away from us in astronomical terms – could be a good place to start. You can read Ignasi’s paper and Rodrigo’s News and Views article over at nature.com/nature.

Host: Noah Baker

Coming up in the show, we’ll be getting an update on the continuing European Xylella crisis – that’s in the News Chat. But before that, Anna Nagle has dropped by the studio to bring us this week’s Research Highlights.

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Interviewer: Anna Nagle

A stash of human bones has confirmed a particularly gruesome habit of Iron Age Celtic warriors. Ancient texts describe how the Celts would decapitate their enemies and then put their embalmed heads on public display. Scientists got a chance to test this claim at a former Celtic settlement site in the south of France. The team examined skull fragments dating back to the third century BC. Not only did the bones have cut marks, suggesting the brains had been removed, the chemical analysis revealed hints of the Celts embalming mixture – things like traces of resins and plant oils, which would have had useful anti-odour properties, and would also have slowed tissue decay. All the better for keeping that battle trophy in display as long as possible. Head on over to the Journal of Archaeological Science to find out more.

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Interviewer: Anna Nagle

Bitcoin may cost more than gold – in energy terms, that is. This virtual cryptocurrency is mined by solving immensely difficult computational calculations, and that takes energy… a lot of energy. In fact, according to a new study it takes about 17 megajoules to mine US$1 worth of bitcoin. That’s more than three times the amount of energy it takes to mine the equivalent value in gold, and more than twice that of platinum. Over a two-and-a-half-year period, researchers also calculated that mining across just four major cryptocurrencies generated as much as 13 million tonnes of carbon dioxide – that’s about the same as a million cars. Bank that research in Nature Sustainability.

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Host: Noah Baker

Clinical trials are a well-established way to test out new medicines. Their methods have been honed over hundreds of years, but the rise in social media poses difficult new problems. How do you keep a trial blind when everyone is connected? Well, reporter Heidi Ledford has written a Feature on this very topic, and Ali Jennings spoke to her in our studio to find out more. He began with the basics.

Interviewer: Ali Jennings

What is a clinical trial?

Interviewee: Heidi Ledford

You know, it’s kind of interesting actually that you ask it that way because a clinical trial can be different things to different people. So, for a researcher, a clinical trial is a chance to test a medicine in the most important setting – in people, in the clinic. For the participants in the trial, for some of them it may be a shot at a better treatment or even a cure for their condition.

Interviewer: Ali Jennings

If I’m a participant in a clinical trial, I want to know that I’m getting the treatment, not the placebo, right? And so, doesn’t that cause a bit of a conflict with the researchers who are trying to blind the trial?

Interviewee: Heidi Ledford

It can, yes, because researchers, you know, their goal really is to get data that is as good and as clean as possible, and if participants do find out that they’re on the placebo or that they’re on the experimental medication that could colour their perception of their own responses to that medication.

Interviewer: Ali Jennings

So, researchers need to keep trial participants from knowing which arm of the trial they’re on, but with the arrival of social media which enables more interaction between participants, does that mean that it’s even harder to keep trials blinded?

Interviewee: Heidi Ledford

That’s the perception, the worry, that’s out there right now among researchers, clinical researchers, in academia and in pharma. There have always been some participants who have tried to figure out whether or not they’re on placebo or on the medication, and that’s – I think – completely understandable. There was a famous case in the early days of the AIDS epidemic when some of the participants in early clinical trials there would pool their medicines, their pills, together, and have pill parties because felt it was unfair for anyone to be on placebo, so they just pooled together the medicines and thought everybody will get something. So, it’s an old phenomenon but there is a concern that with the rise of social media it has a wider reach.

Interviewer: Ali Jennings

As someone looking for access to some of these new treatments, might your community be able to help you to get on to trials of new medicines which maybe otherwise you wouldn’t have been able to?

Interviewee: Heidi Ledford

Yeah, well, you know there’s a positive side to that in that they may find out about clinical trials that they wouldn’t have known about before, so that’s very exciting I think. There is also a concern to that that if participants who are on a trial share the eligibility criteria, you know, ‘Oh, I had to score such and such on a specific memory test,’ or something along those lines, that then other people can say, ‘Okay, well I really want to get on that trial, I need to score that on that test, I’m going to learn how to score that on that test so that I can get into the trial,’ and for some clinical trials that may then affect who’s getting on and who’s not.

Interviewer: Ali Jennings

It sounds like social media is a bad thing. Is that completely true?

Interviewee: Heidi Ledford

Oh no, no, not at all. No, it’s not entirely a bad thing. It’s very empowering for many participants in clinical trials and for their advocates and it’s done wonderful things for them. I mean it gives them a community to share their experiences with. That’s enormous emotional support for some people, particularly if they have a rare condition, you know, to be able to find others who are going through the same experience is really powerful.

Interviewer: Ali Jennings

Can clinical trials evolve to encompass this new social media communication landscape?

Interviewee: Heidi Ledford

I think that’s really the challenge now that’s before researchers to try to incorporate the changing landscape, as you said. You could think, ‘Oh well, participants shouldn’t be discussing these things online,’ but I think a lot of people realise that that’s not a practical solution and instead, maybe they need to evaluate how they’ve designed the trials and, you know, if you do have endpoints or symptoms that you’re looking at that are subjective, is there a way to firm them up so that they’re less likely to be susceptible to influence when you find out about someone else’s experience on the trial and so forth?

Interviewer: Ali Jennings

It’s completely understandable if you’re suffering from a condition that you would want to seek out the best possible treatment for it, but at the same time you might argue that the greater good would be to allow these drugs to be rigorously tested so they can reach the market quicker and then reach all the people who have this condition. So, we have this ethical dilemma, which side should we be pushing towards?

Interviewee: Heidi Ledford

I think it’s always going to have to be a balance between the two somehow. Certainly, many participants in clinical trials will cite altruism as a reason for their participation but when you’re dealing with potentially a terminal illness or if you have a child, in particular, who’s dealing with a potentially terminal illness, I think there’s only so far that altruism can really carry you in that moment. I mean I often think if I were in that position, what would I do, and you know, if it were my child who were sick there’s no mountain I wouldn’t move, right? So, I think that’s a very difficult decision. I don’t know how much we can really push someone to stay. In the end, they have the power.

Host: Noah BakerThat was Heidi Ledford speaking to Ali Jennings. If you’d like to read Heidi’s full Feature article, head over to nature.com/news.

Interviewer: Benjamin Thompson

Finally then on this week’s podcast, it’s time for the News Chat and I’m joined here in the studio by Nisha Gaind, European Bureau Chief here at Nature. Nisha, thanks for stopping by.

Interviewee: Nisha Gaind

You’re very welcome, thanks, Ben.

Interviewer: Benjamin Thompson

Okay for our first story this week, we’re going to talk about a subject that we’ve mentioned on the podcast before and that is the bacterium Xylella fastidiosa.

Interviewee: Nisha Gaind

Yes, so this is a story out of southern Italy and it’s, as you say, something that we’ve followed at Nature for a number of years. There is a bacterium called Xylella fastidiosa which is attacking olive trees in southern Italy and devastating olive groves which are very commercially important crop, and it’s still spreading quite a few years after it was identified and that’s a problem.

Interviewer: Benjamin Thompson

So, I think 2013 was when this bacterium was first detected in Italy then. What’s been going on in the interim?

Interviewee: Nisha Gaind

Immediately it became subject to some very stringent quarantine regulations that apply under European law. Now, the problem with these regulations is that they mean that you often have to uproot and destroy olive trees, some of them are very ancient and some of them are very beloved, to stop an infection from spreading, but those measures have faced quite a lot of opposition from various parts of the communities.

Interviewer: Benjamin Thompson

Right, and we’re in 2018 now then, what’s been going on to stymie this outbreak?

Interviewee: Nisha Gaind

So, these containment measures have stopped and started over the years and they most recently stopped completely in May. Now, in the past few weeks, the regional government of Puglia has actually started tracking the infection again, which is a positive step, but it still hasn’t released enough money for all of these various containment measures to be put in place. So, it looks like this infection may still continue to spread and threaten some really important olive groves.

Interviewer: Benjamin Thompson

Are they any sort of sanctions or things that could happen as a result of this?

Interviewee: Nisha Gaind

Yes, there are. These containment measures are required by European law and the European Commission has long threatened that it would refer Italy to its highest court for violating these laws. The European Commission has now done that – it’s referred Italy to the European Court of Justice – and we’re waiting to see how that will play out, but it could end up restricting or affecting the amount of agricultural subsidies that Italy receives.

Interviewer: Benjamin Thompson

We’re sort of talking national now then, what’s the national Italian government saying about this?

Interviewee: Nisha Gaind

So, this has been quite a long-running controversy. It’s attracted attention from various quarters, from various politicians, and at the moment it’s being discussed in both of the houses of Italy’s national parliament. In one house, the Senate, there is some parliamentarians who are keen to start an enquiry, and they’re actually questioning whether scientists might have misled the public about this crisis. And conversely, in Italy’s other house, there is already a series of hearings underway that is in a way trying to ascertain the truth of what has happened and it’s interviewing scientists and people from the olive industry to figure out what’s really gone on. But it’s a pretty big controversy and there will be more to this story yet.

Interviewer: Benjamin Thompson

Indeed. But let’s move on to our second story today then, Nisha, and well, to be honest with you, this one is a little bit weird.

Interviewee: Nisha Gaind

Yes, this is a really interesting story. It’s about a new technique that basically makes dead mice transparent and hard like plastic, and it’s giving researchers this incredible view into how different types of cell work in the body.

Interviewer: Benjamin Thompson

Right, I mean you say new technique there Nisha, but I think I remember hearing about a thing called CLARITY a few years back. How is this different to that?

Interviewee: Nisha Gaind

So, this technique, which has a wonderful name – it’s called vDISCO – is indeed one of these types of techniques, but it overcomes many of the issues of other methods that allow scientists to turn organs clear. In other techniques, researchers often have to remove these delicate organs from bodies, but vDISCO allows researchers to turn an entire body –

in this case, we’re talking about mice – see-through and rigid, and it preserves the bodies for years.

Interviewer: Benjamin Thompson

I mean this is where I have to ask the obvious question – why?

Interviewee: Nisha Gaind

The simple answer is just to look inside these fantastically complex organs that all animals have. For example, the technique has already been used to look at the way that mysterious vessels run between the skull and the brain, and these are only very recently discovered.

Interviewer: Benjamin Thompson

Can you give us any more information on how it works?

Interviewee: Nisha Gaind

Yeah, so the research – which has just been presented at the Society for Neuroscience meeting this year in California – it uses organic solvents to essentially strip the fats and pigments from the body of a mouse. This also preserves the structure of the mouse’s cells, even though the animal has shrunk quite a lot by up to 60%.

Interviewer: Benjamin Thompson

So, we have our transparent, rigid mouse, okay, so what happens now then?

Interviewee: Nisha Gaind

So now we want to figure out how we actually find out what organs are doing inside this mouse. What the scientists have done is use a particular type of antibody – it’s actually called a nanobody and it’s only found in llamas, camels and alpacas – and they’re very tiny antibodies that can be engineered to stick to specific proteins that are only found in a single type of cell. So, you can use these nanobodies and attach fluorescent markers to them and they pass through tiny blood vessels and into organs and reveal their structure.

Interviewer: Benjamin Thompson

Okay, and these have been used to, as you say, see these kinds of links between the brain that we didn't know were there. How else have they been used? What else have we seen with them thus far?

Interviewee: Nisha Gaind

It’s already been used to look at loads of different systems in the body, including the lymphatic system, and it’s been used to test how severe injuries to the brain and spinal cord affect cells elsewhere in the body, and that’s come up with a few surprises.

Interviewer: Benjamin Thompson

Okay, well finally then for this News Chat then, we’ve got vDISCO, we’ve got transparent mice, we’ve got llama nanobodies… I mean my goodness there’s a lot here, but where do we go next? What are the researchers saying?

Interviewee: Nisha Gaind

There’s so much more, that’s the brilliant thing about it. They think that they can use vDISCO to trace viruses, cancer cells and just a host of other invaders that spread throughout the body, so we’ll be keeping an eye on this.

Interviewer: Benjamin Thompson

Absolutely. Well, thank you, Nisha, and listeners, that’s it for this week’s show but as always, you can find out even more about the latest science news over at nature.com/news.

Host: Noah Baker

And in the meantime, if you’d like to drop us a line, why not send us a tweet (@NaturePodcast) or if you prefer, email us at podcast@nature.com. I’m Noah Baker.

Host: Benjamin Thompson

And I’m Benjamin Thompson. Thanks for listening everyone.

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