Host: Nick Petrić Howe
Welcome back to the Nature Podcast. This week, could scientists develop a simple test for pre-eclampsia?
Host: Shamini Bundell
And the problem of urine in our waste. I’m Shamini Bundell.
Host: Nick Petrić Howe
And I’m Nick Petrić Howe.
[Jingle]
Interviewer: Nick Petrić Howe
First up on the show: pre-eclampsia. This is an extremely serious condition that can occur during pregnancy, characterised by high blood pressure. In severe cases, it can lead to kidney dysfunction, seizures and even death. Early detection of pre-eclampsia would give pregnant people more options for treatment, and a new study aims to allow just that – detecting pre-eclampsia earlier with just a simple blood test. I called up one of the authors, Stephen Quake, to find out more, and I started by asking how many people this disorder affects.
Interviewee: Stephen Quake
Pre-eclampsia is a very common disease in pregnancy, and it’s the cause of something like 14% of maternal deaths each year globally and it’s the second leading cause of maternal death. The costs are enormous. In the US it’s something like US$2 billion a year in care. It’s a very common thing and it’s something that is preventable if we’re able to be diagnosed earlier.
Interviewer: Nick Petrić Howe
And how is it currently diagnosed and at what point will people find out that they have this?
Interviewee: Stephen Quake
So, pre-eclampsia is a hypertensive disease, so high blood pressure, hypertension, and so today it’s mostly diagnosed when you have that high blood pressure and you’re already feeling the symptoms of the disease. So, when you’re symptomatic is when it’s diagnosed. Our work was aimed at finding ways to predict who is going to get it before you have high blood pressure and hypertension.
Interviewer: Nick Petrić Howe
And so you mention there you were looking at different ways to detect this, looking for non-invasive methods, so what were you looking for?
Interviewee: Stephen Quake
So, we’re using a phenomenon called cell-free RNA. So, it turns out that every tissue in your body contributes RNA into the blood, and when you’re pregnant it’s coming from the placenta and fetus as well as all the maternal tissues, and RNA is the cells’ way of expressing proteins. It’s that intermediate step. When it wants to express a protein, the gene is transcribed from the genome, it’s copied into RNA and then the RNA is used as a template to make the protein. So, it’s really a very valuable measure of what the cells are doing at any given point in time.
Interviewer: Nick Petrić Howe
And so, this RNA, is it just floating around the body waiting to be picked up?
Interviewee: Stephen Quake
It is floating around the body, and much of it gets digested, but some of it survives and circulates through the blood, and that’s the little bit that we analyse.
Interviewer: Nick Petrić Howe
And what could that tell us about pre-eclampsia?
Interviewee: Stephen Quake
Because the body is changing due to disease, hypertension is happening and high blood pressure is happening and that’s going to cause changes, and even before those symptoms are manifested, the changes are happening in the tissues, and so the RNA is changing because the cells are either causing the disease or responding to it, and it’s those messages that we’re analysing and that are providing the earliest signals of disease.
Interviewer: Nick Petrić Howe
So, in this study, you did a clinical trial of 199 people and you had 404 blood samples from them. What were you able to find from this and what were the sort of markers of pre-eclampsia?
Interviewee: Stephen Quake
What we found was roughly 500 genes whose expression levels change through the course of pregnancy in the women who had pre-eclampsia versus those who didn’t. We analysed them to try to understand which cell types they came from and what was kind of the underlying biology to be able to learn something about that and particularly cells of the immune system, neuromuscular cells, endothelial cells, and relate that to the sort of biological cause of pre-eclampsia. And then we also found a subset of those genes that would predict who would get pre-eclampsia before the symptoms manifested, and so we think that panel of genes could form the basis of a diagnostic screen to help understand who is at risk. Now, it must be said that this is all still very early and to really understand if there’s going to be clinical value, a large, blinded trial has to be done. But I think it’s an exciting proof of principle that indicates what might be possible in the field.
Interviewer: Nick Petrić Howe
And at what point does pre-eclampsia typically occur and then at what point were you able to detect the changes that indicated that pre-eclampsia was a risk?
Interviewee: Stephen Quake
So, often the onset is in middle to late pregnancy, and formally they would say after 20 weeks of gestation they are on the lookout for it. In our case, we were seeing signals as early as 12 weeks.
Interviewer: Nick Petrić Howe
And there were these changes that you detected. Sometimes gene expression changes, RNA changes can be quite subtle. Were they quite clear? Were they quite distinct between people who developed pre-eclampsia and people who didn’t?
Interviewee: Stephen Quake
Yes, these were really quite distinct, and we were happy that we were able to replicate them on other cohorts, and so it was something that has us very comfortable, I think with the rigour of the analysis and the reproducibility of the effect.
Interviewer: Nick Petrić Howe
What was the sort of diversity of the people involved? Do you think this was a representative sample? Would these changes in gene expression occur in the majority of people who were pregnant, or how representative do you think this group was?
Interviewee: Stephen Quake
Yeah, that’s a really interesting question, and it’s one that has been an open question in the field of cell-free RNA for a number of years because it’s such a young field. We went out of our way to recruit a fairly diverse cohort here, and one of the really amazing things about the study was that in our validation cohort, we had some ethnicities that weren’t represented in the discovery cohort and the results held for them. And so, both on the basis of the diversity of the cohort and the fact that the validation cohort was even more diverse, we’re feeling pretty good about that.
Interviewer: Nick Petrić Howe
So, you had a diverse group of people to begin with when you were just looking for these signatures of pre-eclampsia, but then when you went to validate this with another group of people to see if those markers were there again, it was an even more diverse group of people. So, taking this altogether, what do you think the implications of this study are?
Interviewee: Stephen Quake
Well, I mean, we’re hoping it’s going to form the basis of a test that’s going to save a lot of lives going forward. This is all about trying to improve healthcare for expectant mothers and their unborn babies, and pregnancy shouldn’t be a thing that has fatalities associated with it, and I hope this work can contribute to realising that vision of eliminating deaths during pregnancy.
Interviewer: Nick Petrić Howe
That was Stephen Quake from Stanford University and also the Chan Zuckerberg Biohub, both in the US. For more on this study, check out the paper in the show notes.
Host: Shamini Bundell
Coming up, we’ll be hearing about the issue of urine in sewage and what can be done about it. Right now, though, it’s time for the Research Highlights with Dan Fox.
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Dan Fox
A new smart camera could help machine-vision systems to see in a variety of lighting conditions, by taking inspiration from the human retina. Machine-vision systems are networks of cameras and computers that analyse visual information, making them useful for tasks such as quality-control inspections. These systems need to be able to see objects in a wide range of lighting conditions, something normally achieved using intricate optical components, circuitry and algorithms. Humans, however, can discern objects in both dark and bright environments because our retinas change their light sensitivity to adapt to the illumination level. Now, researchers have carefully designed sensors to emulate this behaviour, by using light detectors called phototransistors made from an ultrathin semiconductor material. The new sensors can perceive objects in a light-intensity range that is substantially wider than the current state-of-the-art silicon alternatives. And as the light-level adaptation happens within the sensor itself, they can also reduce the amount of complex circuitry needed within a device. Focus your human retinas on that research in Nature Electronics.
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Dan Fox
Centuries ago, the people living on South America’s Pacific Coast carefully stacked the remains of human spines onto reed sticks – a practice researchers think served to repair damage caused by European tomb raiders. The Chincha people flourished in what is now Peru from AD 1000 until the arrival of Europeans in the sixteenth century, when most of the Chincha population was wiped out by disease, famine and political turmoil. Researchers surveying ancient graves in the Chincha Valley documented 192 reed sticks with human vertebrae threaded onto them; one stick was also capped with a human skull. The researchers estimate that the objects were created about 450 years ago, around the time that newly arrived Europeans opened and robbed many graves. They think that the Chincha people may have threaded vertebrae onto sticks to reconstruct their dead after the remains were damaged by looters. Read that research in full in Antiquity.
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Host: Shamini Bundell
Next up, we need to talk about toilets, because the way we manage our waste can cause big problems. Even treated sewage water can contain high levels of chemical contaminants. These can act as fertilisers and cause eutrophication – blooms of harmful algae – in our waterways. And the main culprit for these contaminants? Urine. Reporter Ali Jennings has been finding out how we might tackle our pee problem. He spoke with Chelsea Wald, a science writer who has quite literally written the book on toilets.
Interviewee: Chelsea Wald
So, the sort of radical idea that people have had since the 1990s is what if we could separate urine from the rest of sewage. You could send the rest of sewage to a wastewater treatment plant, and then you could treat the urine and reuse it as fertiliser in agriculture.
Interviewer: Ali Jennings
Just from a practical perspective, how do you go about separating urine from the rest of human waste, if you wanted to collect it?
Interviewee: Chelsea Wald
Right, so the practical part is really the crux of the problem. So, what you want to do is you want to do it at the toilet. But that’s actually remarkably difficult to do. So, the first urine-diverting toilets had a little bowel at the front, like a little basin, that caught the urine. These are still around in various places. And the problem with that is that it requires you to aim, which most people find awkward. I mean, the toilet as we know it is so convenient, it’s so easy to use, that people aren’t willing to take a step back from that and kind of downgrade.
Interviewer: Ali Jennings
So, what’s happening now in the world of urine diversion?
Interviewee: Chelsea Wald
There’s been what some people think is a big breakthrough on the toilet front, so on the interface front.
Interviewer: Ali Jennings
So, the porcelain end?
Interviewee: Chelsea Wald
Yes, the porcelain end, the bum end. It’s called the urine trap. It’s from an Austrian design firm in collaboration with some researchers and funded by the Bill & Melinda Gates Foundation. And the way it works is that it uses something called the teapot effect, which is if you think about the way that water comes out of a teapot and sort of dribbles inconveniently down the side instead of pouring into the cup. In this case, the urine dribbles down the front inside of the toilet into a separate hole that the user doesn’t even see.
Interviewer: Ali Jennings
And what happens to it then?
Interviewee: Chelsea Wald
What people are looking at are basically two different types of systems. One that attaches directly to the toilet. The other idea is to kind of put it in a large building – and there’s technologies that work better at a somewhat larger scale for treatment – send the urine to a facility in the basement that then treats the urine. And then there’s going to be some kind of service probably that comes, services the device, picks up the product and makes sure that it gets to a consumer eventually.
Interviewer: Ali Jennings
And what are the challenges that come with processing the urine after you’ve collected it?
Interviewee: Chelsea Wald
So, the main component of urine is urea, other than water, and urea is a very common fertiliser, but it’s actually really hard to get it out of the urine because as soon as it comes out of the body, there’s a reaction that transforms it into ammonia, which stinks, which is one of the reasons why urine stinks. And then that ammonia is polluting also and it can carry the nitrogen off. So, you can let this reaction go ahead and then deal with the ammonia, or you can try to stop the reaction, usually by raising or lowering the pH really, really quickly because the reaction happens really quickly, and then you can treat the urine more or less in the form that it came out of the body.
Interviewer: Ali Jennings
Is there a good example of one of these systems being incorporated into an obvious use?
Interviewee: Chelsea Wald
So, there’s a pilot project ongoing in Sweden. They are doing it on the island of Gotland. Gotland is the largest island in Sweden. It has a lot of environmental problems. One of them is that they have water shortages. They just can’t afford to flush their toilets very much, and the other one is that they have a lot of eutrophication in their water. And so, what they’re doing is they’re creating a system where they collect urine from waterless urinals at festivals. They then take the urine and dry it and make a powder out of it that fits into conventional farming equipment. They’ve given it to a local farmer to grow barley, and then they give that barley, once it’s been malted, to a local brewery and they’re making a local beer out of it, an ale.
Interviewer: Ali Jennings
And perfect circularity – the beer eventually, you would imagine, ends up back in those same urinals.
Interviewee: Chelsea Wald
Yes, in fact, yes, that’s the most delightful part of the project in my mind.
Interviewer: Ali Jennings
How do people feel about eating food which has been fertilised with the products of urine?
Interviewee: Chelsea Wald
So, there’s been a lot of fear that people wouldn’t accept it just because they’d be grossed out. The research that’s been done has shown that in fact there are a lot of people who have no problem with it, they’re willing to accept it, and it really depends on the location. I mean, taboos about human waste vary a lot country to country and culture to culture. So, apparently, France, China and Uganda would be very accepting, whereas a place like Jordan, where there’s more of a religious taboo on human waste in general, would be less accepting. Researchers are actually kind of more worried about the inertia in the overall system. It’s just very difficult to get food companies, farmers, regulators, all of those players, are very slow to change, and so that’s where the researchers that I’ve talked to expect the most resistance to come from. It’s not actually from individual food consumers.
Host: Shamini Bundell
That was Chelsea Wald talking to reporter Ali Jennings. If you want to find out more, you can read Chelsea’s feature article. Also, if you want yet more toilet science, then Chelsea has also written a book on the topic, Pipe Dreams. We’ll put a link to the article and a review of Chelsea’s book in the show notes.
Host: Nick Petrić Howe
Finally on the show, it’s time for the Briefing chat, where we discuss a couple of articles that have been highlighted in the Nature Briefing. Shamini, what have you found for us this time?
Host: Shamini Bundell
Well, this week, I have been reading an article in Nature about the Winter Olympics, which have just recently started, and China’s plans to make them the first fully carbon-neutral Winter Olympics.
Host: Nick Petrić Howe
So, it sounds like quite an ambitious target to make it carbon-neutral because it’s a huge event, there’s lots of things going on. How are they planning to do this?
Host: Shamini Bundell
Absolutely. There is a lot to cover, and there have been previous attempts at carbon-neutral Olympics, but China says their plans are the most wide-covering, considering many different kinds of emissions and considering indirect emissions caused by the games as well. So, they’ve got lots and lots of things in place to do this. So, Beijing already hosted the Summer Olympics in 2008, and they’re actually, I think, the first city to host both a winter and a summer, so they have been, for example, reusing some of the buildings that they’ve got there. When they’ve been building new buildings, they’ve been making them to a really high green, energy-efficient standard or making temporary buildings which have a lower carbon footprint. They’ve been doing things like using electric- or hydrogen-powered vehicles and they’ve made sure that all of their Olympics venues are using renewable power.
Host: Nick Petrić Howe
Well, one of the things I’ve been seeing, and as you said there, they’ve hosted both the Summer and the Winter Olympics, is this is quite a dry region, and they’ve been having to create quite a lot of snow for the Olympics to occur. It seems to be that that would be quite a carbon-intensive thing. How are they tackling that, for instance?
Host: Shamini Bundell
Yeah, absolutely. So, the snow sports are taking place in very cold but rather dry regions, so, yes, they’re transporting quite a large amount of water, which obviously has got a big carbon footprint. And there are lots of things that they’re doing that, obviously, you can’t make everything completely renewable or carbon neutral. So, what they’re doing for this excess is carbon offsetting, so for example planting a large number of trees. But there are people who are saying this is pushing the problem further down the road. Those trees, you don’t necessarily know what’s going to happen to them, and that as a sort of planet we shouldn’t be overly relying on carbon offsetting as a way to manage our emissions.
Host: Nick Petrić Howe
And that’s a good point as well, what has been the reaction of scientists and especially climate scientists to this ambitious pledge to make it carbon neutral?
Host: Shamini Bundell
There’s a mixture of reactions, both positive about everything that’s being done and maybe sceptical about whether it’s as much as is being claimed. So, for example, one energy systems researcher says that the value of this achievement is in demonstrating that broader carbon-neutral activities are possible. Of course, in a way, this Winter Olympics is a sort of drop in the ocean of China’s annual carbon dioxide emissions of 11 billion tons compared to this games’ estimated footprint is about 1.3 million tons. But they’re also doing more than any previous games has done, helped somewhat by COVID because they’ve basically got no international tickets, so you haven’t got all the footprints from all the spectators flying in due to their sort of very tight COVID policies. And they’ve also just massively limited the number of local tickets as well, so that’s certainly something that’s reducing the overall footprint of these games.
Host: Nick Petrić Howe
Well, what might this mean for future Olympic events? Will it inspire people to do more?
Host: Shamini Bundell
Yeah, the International Olympics Committee are definitely interested in discussing with future hosts how green their Olympics can be. There is an interesting point at the end of this article. One of the researchers interviewed notes that by the end of the century, due to sort of changes in temperature and snow conditions, the majority of cities that have hosted any of the past 21 Winter Olympics would struggle to host another. So, this researcher says that the International Olympics Committee would need to be even more creative and flexible in how they host future games. So, perhaps you shall hear more Olympics coverage on the Nature Podcast with respect to that. So, Nick, what’s your story for this week?
Host: Nick Petrić Howe
Well, my story is another story that’s been reported in Nature, and this is about the first millimetre-range radio telescope to be built in Africa.
Host: Shamini Bundell
Okay, so what is a millimetre-range telescope and kind of how many of them are there all over the world?
Host: Nick Petrić Howe
So, millimetre-range telescopes are ones that can detect radio waves over very small wavelengths, so 1 millimetre. And there’s one that you’ll be quite familiar with, Shamini, which is the Event Horizon Telescope, which famously…
Host: Shamini Bundell
Oh yeah!
Host: Nick Petrić Howe
Yes, you were there at the press conference where they announced the first image of the event horizon of a black hole. So, the Event Horizon Telescope is a network of such telescopes that can actually image these things at the edges of black holes and get that really, really fine resolution. And this new telescope to be built in Namibia will actually fill a gap in the Event Horizon Telescope and allow for further images in the future.
Host: Shamini Bundell
Wow, so this one in Namibia is the first one in the whole of Africa to have been built. Why hasn’t there been many of these before?
Host: Nick Petrić Howe
Well, there are actually a fair few different telescopes across the African continent, and actually it’s a good place for it. There are often low populations and not much light pollution, so it’s a good place for telescopes, but such telescopes require a lot of technical expertise to operate and to be maintained. And historically, it’s been a challenge to find trained scientists and engineers in those parts of Africa. However, this telescope and others are starting to promote that and increase the amount of engineers and scientists that are trained in such things, and so the hope is that more telescopes will lead to more scientists and more scientists will lead to yet more telescopes, and then we’ll have a whole range of telescopes across Africa.
Host: Shamini Bundell
And who has built this particular telescope and what are they looking for?
Host: Nick Petrić Howe
So, this telescope is actually already in place in Chile, so it’s being donated by the Onsala Space Observatory in Sweden and the European Southern Observatory. And so, they’re going to transport it, presumably bit by bit, from Chile to Africa, and it’s going to be rebuilt there and repurposed. So, this will cost around US$25 million to be done, and once done it will be, as I said, one of these millimetre-range radio telescopes. Part of it will be as part of this Event Horizon Telescope network, but the other part will be for Namibian projects.
Host: Shamini Bundell
So, yet more exciting space science incoming for us to report on then.
Host: Nick Petrić Howe
Absolutely, so, at the moment, this telescope is undergoing a critical design review to determine where exactly is going to be the best place for it, and they reckon in about five years’ time it will be ready to start taking in its first photons and imaging the greater Universe.
Host: Shamini Bundell
Wow, that’s a long time, five years to set it up. We shall have to be patient then to be reporting on these findings. Well, thank you, Nick. And listeners, if you’re interested in more stories like these then why not check out the Nature Briefing. We’ll pop a link of where you can sign up to that along with the stories that we’ve discussed in the show notes.
Host: Nick Petrić Howe
That’s all for this week. If you want to get in touch with us then you can. We’re on Twitter - @NaturePodcast. Or for a good old-fashioned email then you can reach us at podcast@nature.com. I’m Nick Petrić Howe.
Host: Shamini Bundell
And I’m Shamini Bundell.