The antioxidant benefits of sleep

Researchers from Columbia University in New York have found that short-sleeping fruit fly mutants shared the common defect of sensitivity to acute oxidative stress, and therefore concluded that sleep supports antioxidant processes. In a study published in PLOS Biology, the researchers reasoned that if sleep is required for a core function of health, animals that sleep significantly less than usual should all share a defect in that core function. They used a diverse group of short-sleeping Drosophila mutants and found that these short-sleeping mutants do indeed share a common defect: they are all sensitive to acute oxidative stress. Oxidative stress results from excess free radicals that can damage cells and lead to organ dysfunction. Toxic free radicals, or reactive oxygen species, build up in cells from normal metabolism and environmental damage. If the function of sleep is to defend against oxidative stress, then increasing sleep should increase resistance to oxidative stress. The researchers used both pharmacological and genetic methods to show that this is true. Finally, the authors proposed, if sleep has antioxidant effects, then surely oxidative stress might regulate sleep itself. Consistent with this hypothesis, they found that reducing oxidative stress in the brain by overexpressing antioxidant genes also reduced the amount of sleep. Taken together, these results point to a bidirectional relationship between sleep and oxidative stress—that is, sleep functions to defend the body against oxidative stress and oxidative stress in turn helps to induce sleep. This work is relevant to human health because sleep disorders are correlated with many diseases that are also associated with oxidative stress, such as Alzheimer’s, Parkinson’s and Huntington’s diseases. Sleep loss could make individuals more sensitive to oxidative stress and subsequent disease; conversely, pathological disruption of the antioxidant response could also lead to loss of sleep and associated disease pathologies.

Ethical concerns about Chinese organ transplants

A University of Auckland researcher, Associate Professor Phillipa Malpas, has raised ethical concerns about cases where New Zealand patients may travel to China for an organ transplant. Writing in the New Zealand Medical Journal, Professor Malpas said that, while Chinese officials have given assurances that organs would not be taken from executed prisoners, the practice seems to be ongoing and poses an ethical dilemma for health professionals whose patients may travel to China for a transplant. An accompanying editorial notes a lack of accurate data about current practices within China means that there is uncertainty about what our response should be. The editorial states that most New Zealand transplant surgeons already advise their patients against travelling overseas to purchase an organ transplant and that doctors are unable to enforce travel bans or deny medical care to those who have received transplants elsewhere. “A number of ethical tensions arise for [New Zealand] health professionals if they suspect or know their patient is considering procuring an organ from China, or if their patient returns to [New Zealand] with a transplanted organ,” Associate Professor Malpas wrote. “Transplant surgeons from China who intend to continue their training and practice at home, should not be permitted to further their transplant training in [New Zealand]. It is recommended that professional medical bodies provide formal guidance for health professionals engaged with patients who are organ transplant candidates.”

Iceman’s last meal was a fatty binge

Italian researchers have conducted the first in-depth analysis of the stomach contents of the Iceman – a human body discovered in 1991 in the Eastern Italian Alps that was later determined to be the oldest naturally preserved ice mummy, at 5300 years old. Among other things, their findings show that the Iceman’s last meal was heavy on the fat. “By using a complementary multi-omics approach combined with microscopy, we reconstructed the Iceman’s last meal, showing that he has had a remarkably high proportion of fat in his diet, supplemented with wild meat from ibex and red deer, cereals from einkorn, and with traces of toxic bracken,” the researchers wrote in Current Biology. The analysis hadn’t happened earlier because scientists were initially unable to identify the Iceman’s stomach. That’s because it had moved up during the mummification process. In 2009, his stomach was spotted during a re-investigation of computed tomography scans, and an effort to analyse its contents was launched. “The stomach material was, compared to previously analyzed lower intestine samples, extraordinarily well preserved, and it also contained large amounts of unique biomolecules such as lipids, which opened new methodological opportunities to address our questions about Otzi’s diet,” the researchers wrote. They combined classical microscopic and modern molecular approaches to determine the exact composition of the Iceman’s diet before his death. The broad-spectrum approach allowed them to make inferences based on ancient DNA, proteins, metabolites and lipids. The analysis identified ibex adipose tissue as the most likely fat source. In fact, about half of the stomach contents were composed of adipose fat. While the high fat diet was unexpected, the researchers wrote that it “totally makes sense” given the extreme alpine environment in which the Iceman lived and where he was found. The analysis indicated that the wild meat was eaten fresh or perhaps dried. While the presence of toxic bracken particles is more difficult to explain, the researchers say it’s possible that the Iceman had intestinal problems related to parasites found earlier in his gut and took the bracken as a medicine. On the other hand, he may have used the fern’s leaves to wrap food and ingested toxic spores unintentionally. Their analysis also revealed traces of the original gut bacterial community present in the Iceman’s intestinal contents. The researchers say they plan to conduct further studies aimed to reconstruct the ancient gut microbiomes of the Iceman and other mummified human remains.

What’s new online at the MJA

16 July Perspective: New enhanced influenza vaccines for older Australians: what promise do they hold?
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16 July Podcast with Professor Kristine Macartney, Director of the National Centre for Immunisation Research and surveillance … OPEN ACCESS permanently

16 July Research letter: Ethics and site-specific governance approvals for multicentre, intersector health care research
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16 July Podcast with Dr Christopher Freeman, a pharmacist and Clinical Senior Lecturer at the University of Queensland … OPEN ACCESS permanently

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