在这个新的sflash, we discover why soy cuts cancer recurrence rates and how a case of mistaken identity spells trouble for endangered fish. Plus, a computer model for unclogging coronary arteries and how a book is as unique as a fingerprint...
In this episode
Soy stops breast cancer recurrence
Women who eat soy products are much less likely to die from or develop a recurrence of breast cancer.
A paper in JAMA by Xiao Shu and colleagues followed up over 5000 Chinese breast cancer survivors aged 20 to 75 for up to 7 years. The study also involved collecting lifestyle data and dietary information including soy-based food intake.
After a median follow-up of 3.9 years there had been 444 deaths and 534 disease recurrences. But when the team organised the data according to soy intake the found a striking difference: the women who ate the largest amount of soy-based food per day were nearly 30% less likely to have died and 32% less likely to have developed cancer recurrence compared with women who ate the least. The effect showed a linear "dose-response" relationship, with the protective effect peaking at an intake of about 11g per day. The reason for the protective effect is not entirely clear but scientists suspect that it may be related to the presence of oestrogen-like isoflavone molecules that are present in soy and known as phyto-oestrogens.
Paradoxically, some scientists had expressed concerns that these molecules might actually aggravate breast cancer therapy, particularly for hormone-sensitive tumours which can be oestrogen-driven, but this study shows that's not true. Instead the scientists found that tamoxifen (which blocks the growth-promoting effects of oestrogens on cancer cells) and soy food could improve survival.
"We found that soy food is safe and was associated with lower mortality and recurrence among breast cancer patients," say the researchers. "This study suggests that moderate soy food intake is safe and potentially beneficial for women with breast cancer."
A fishy case of mistaken identity
An endangered fish in the North Atlantic could be in even more trouble than previously thought because it turns out that for a long time it has been mixed up with another, less-threatened species.
White marlin are magnificent, fast-swimming, ocean-going fish that can weigh in at over 80kg and grow up to 3m long, and each one has an amazing long spear on their nose. But they are not doing well. They are the prized target of a multimillion dollar sport fishery in America and caught accidentally by longline fisheries aimed at tuna and swordfish.
A few years ago it was estimated that the number of White Marlin left in the wild has been driven down to only around 12% of the number needed to maintain a healthy population. But it now seems they could be doing even worse still, because scientists have been confusing them with another species that looks like it, called the Roundscale Spearfish.
That's the finding published in the journal Endangered Species Research by an international team of marine biologists co-led by Laurence Beerkircher from the NOAA Fisheries Service and Mahmood Shivji from the Guy Harvey Research Institute both in the US.
By sifting through DNA samples from the past decade they found that almost 30% of fish reported in fisheries statistics as White Marlin, were in fact Roundscale Spearfish, an enigmatic look-a-like fish that we know very little about and only made itself known to science in 2006 when a genetic study identified it as a separate species.
The team also used computer simulations to work out how the abundance Roundscale Spearfish will alter assessments of White Marlin populations in the past and future. Unfortunately, the crucial piece of missing information is whether spearfish have always made up 30% of the catches, or if that proportion has changed over time. Without that information, it leaves scientists with a very hazy picture of how both these fish are doing making it extremely difficult to manage and conserve them properly.
现在白色的马林已经两次提出了protection under the US Endangered Species Act (which would put an end to the lucrative trophy fishery), and twice it has been turned down based largely on population studies suggesting they have been increasing in abundance. But now that the Roundscale Spearfish has come onto the scene, we can't be at all sure if those increases really happened.
We may sometimes think of taxonomy - the science of species identification - as rather an old-fashioned pursuit confined to the dusty corridors of museums. Far from it, this study highlights just how important it is for us to understand what species there are in the world, especially the many ocean-dwelling species that we are busy hunting towards extinction.
Computer model gets to heart of blocked artery problem
A new computer model promises to dramatically improve the outcomes when clogged heart arteries are unblocked and propped open with metal stents.
The process of treating heart disease like this, with angioplasty and stenting, known as PCI - percutaenous coronary intervention, has revolutionised the treatment of heart disease; patients now only rarely have to undergo risky open-heart arterial bypass procedures.
Instead, tubes are threaded into the coronary arteries via an artery in a patient's leg and dye is used to identify blockages. The narrowed portions of the artery are then re-opened by briefly inflating a balloon inside the vessel before deploying a metal stent, which resembles a miniature cage, to ensure that the artery remains patent.
But when doctors first began to do this they discovered that new cells would grow around the stent, subsequently re-occluding it. The problem was tackled by using stents impregnated with a drug (a so-called DES - drug eluting stent) to block this cell growth. But unfortunately, whilst highly effective, in some cases these stents provoked blood clots and heart attacks in some patients.
Now a team in Harvard have worked out why and how to prevent the problem.
Writing in PLoS one, Vijaya Kolachalama and his colleagues have designed a computer algorithm that can predict how blood behaves downstream of stents and explains why, in some cases, patients have suffered repeat problems. The model shows that when stents are plumbed into sections of arteries close to points where the vessels branch, the change in blood flow causes the drug to build up at certain points along the vessel wall, triggering damage.
According to study co-author Elazer Edelman, "by observing the arterial distribution patterns for various settings, we understood that drug released from the stent does not reach uniformly to all regions of the vessel and this non-uniformity depends on where the stent is placed in the artery as well as blood flow that is entering the vessel." This should make it much easier for doctors to position stents with greater safety in future and may help designers to develop novel stents capable of avoiding these problems. It may also herald the future arrival of individualised stents, bespoke built to match the specific demands of a patient's vasculature.
09:25 - Read my words
Read my words
New computer software can read a book's literary fingerprint that is unique to the author who wrote it...
It turns out that as books get longer, even the very best writers eventually start to run out of new words to use. But, the rate at which new words drop off depends on the skill of the author and is always the same for each author, giving them a unique word-frequency fingerprint.
Based on analysis of books and stories by three great writers, Herman Melville, Thomas Hardy and DH Lawrence, a team of researchers from Sweden, led by Sebastian Bernhardsson, have come up with the idea that inside every writer's head is a 'meta-book'. Writers reach into their own personal meta-book and pull out words to put down on paper or computer screen.
The study published in the New Journal of Physics provides insights into the way language is used especially by the greatest writers.
The findings go against a 75 year old theory, called Zipf's law, which suggested that for any written work, the frequency of any word is inversely proportion to its rank. So, if the word "the" is most frequently used and accounts for 7% of all the words used, the next most frequent word "and" accounts for around 3.5% and so on.
But, rather than a universal literary rule, this new study shows that linguistic ability of individual authors is more important in determining their new-word frequency.
团队计划进行类似的研究n other literary works, and eventually think it should be possible to pick out an unidentified author from the fingerprint left in their words.
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