Food for thought: Eat your way to dementia

Sugar junkies take note: a calorific diet isn't just bad for your body, it may also trigger Alzheimer's disease

Editorial: "Brain diabetes: the ultimate food scare"

SUZANNE DE LA MONTE's rats were disoriented and confused. Navigating their way around a circular water maze - a common memory test for rodents - they quickly forgot where they were, and couldn't figure out how to locate the hidden, submerged safety platform. Instead, they splashed around aimlessly. "They were demented. They couldn't learn or remember," says de la Monte, a neuropathologist at Brown University in Providence, Rhode Island.

A closer look at her rats' brains uncovered devastating damage. Areas associated with memory were studded with bright pink plaques, like rocks in a climbing wall, while many neurons, full to bursting point with a toxic protein, were collapsing and crumbling. As they disintegrated, they lost their shape and their connections with other neurons, teetering on the brink of death.

Such changes are the hallmarks of Alzheimer's disease, and yet they arose in surprising circumstances. De la Monte had interfered with the way the rats' brains respond to insulin. The hormone is most famous for controlling blood sugar levels, but it also plays a key role in brain signalling. When de la Monte disrupted its path to the rats' neurons, the result was dementia.

Poor sensitivity to insulin is typically associated with type 2 diabetes, in which liver, fat and muscle cells fail to respond to the hormone. But results such as de la Monte's have led some researchers to wonder whether Alzheimer's may sometimes be another version of diabetes - one that hits the brain. Some have even renamed it "type 3 diabetes".

115m people globally will get Alzheimer's by 2050

If they are right - and a growing body of evidence suggests they might be - the implications are deeply troubling. Since calorific foods are known to impair our body's response to insulin, we may be unwittingly poisoning our brains every time we chow down on burgers and fries. People with type 2 diabetes, who have already developed insulin resistance, may be particularly at risk. "The epidemic of type 2 diabetes, if it continues on its current trajectory, is likely to be followed by an epidemic of dementia," says Ewan McNay of the University at Albany in New York. "That's going to be a huge challenge to the medical and care systems."

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Large NIH projects cut

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Budget woes force institutes to scrutinize expensive, non-competitive programmes.

• Sara Reardon

12 November 2013

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A sample of the thousands of protein structures solved with the help of a US National Institutes of Health programme that has now been closed down.

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climate models shows increased tropical cyclone activity over the 21st century

A recently developed technique for simulating large [O(104)] numbers of tropical cyclones in climate states described by global gridded data is applied to simulations of historical and future climate states simulated by six Coupled Model Intercomparison Project 5 (CMIP5) global climate models. Tropical cyclones downscaled from the climate of the period 1950–2005 are compared with those of the 21st century in simulations that stipulate that the radiative forcing from greenhouse gases increases by over preindustrial values. In contrast to storms that appear explicitly in most global models, the frequency of downscaled tropical cyclones increases during the 21st century in most locations. The intensity of such storms, as measured by their maximum wind speeds, also increases, in agreement with previous results. Increases in tropical cyclone activity are most prominent in the western North Pacific, but are evident in other regions except for the southwestern Pacific. The increased frequency of events is consistent with increases in a genesis potential index based on monthly mean global model output. These results are compared and contrasted with other inferences concerning the effect of global warming on tropical cyclones.
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Did climate change cause Typhoon Haiyan?

There is limited evidence that warming oceans could make superstorms more likely.

• Quirin Schiermeier

11 November 2013

A large ship that washed ashore in Tacloban, the Philippines, on 10 November during Typhoon Haiyan — the most violent tropical storm on record.

AARON FAVILA/AP PHOTO

As the Philippines assesses the havoc caused by Typhoon Haiyan, which according to some reports has killed as many as 10,000 people, speculation is heating up as to whether the disaster might be a manifestation of climate change. Speaking today on the first day of United Nations climate talks in Warsaw, the head of the Philippines delegation, Yeb Sano, said that he will stop eating until negotiators make "meaningful" progress.

But can the devastating storm be linked to the changing global climate? Nature wades into the evidence.

Was Haiyan the strongest storm ever measured?

Apparently, yes. With sustained wind speeds of more than 310 kilometres per hour, Haiyan was the most powerful tropical cyclone to make landfall in recorded history. The previous record was held by Hurricane Camille, which hit Mississippi in 1969 with wind speeds of just over 300 kilometres per hour.

It is the third time that disaster has struck the Philippines in less than 12 months. In August, Typhoon Trami caused massive flooding on the island of Luzon. And in December 2012, Typhoon Bopha killed up to 2,000 people and caused some US$1.7 billion in damage on the island of Mindanao. Haiyan could easily surpass that figure: its total economic impact could reach US$14 billion, according to a report by a senior insurance analyst at Bloomberg Industries, a data company in New York.

Haiyan's death toll might have been much bigger had so many people in the Philippines not heeded storm warnings and fled at-risk areas.

What’s the difference between a cyclone, a typhoon and a hurricane?

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They are just different names for the same type of extreme weather phenomenon occurring in different parts of the world. These storms are called hurricanes in the Atlantic and northeastern Pacific oceans, typhoons in the northwestern Pacific and cyclones in the south Pacific and Indian Ocean.

Are such storms getting worse in a warming world?

This is the million-dollar question, but there is not yet a scientific consensus on how to answer it.

Storms receive their energy from the ocean, so it would seem logical that they would get stronger, and perhaps also more frequent, as the upper layers of tropical oceans get warmer. The potential intensity of tropical storms does increase with warmer sea surface temperatures. However, the effect of warming seas could be counteracted by the apparent increase in the strength of shearing winds — winds blowing in different directions and varying in strength at different altitudes. Shearing winds tend to hinder the formation of storms, or tear them apart before they can reach extreme strength.

On balance, many climate researchers think that it is plausible that tropical-storm activity will rise as the planet warms. There is some evidence¹ that storm intensity has increased over the last three decades, but reliable data are limited to the north Atlantic, where observations are most abundant. In other places, the evidence is not yet conclusive².

The Intergovernmental Panel on Climate Change (IPCC) in its latest report cautiously summarizes the current state of knowledge:

“Time series of cyclone indices such as power dissipation, an aggregate compound of tropical cyclone frequency, duration, and intensity that measures total wind energy by tropical cyclones, show upward trends in the North Atlantic and weaker upward trends in the western North Pacific since the late 1970s, but interpretation of longer-term trends is again constrained by data quality concerns.”

Global climate models are too coarse to resolve relatively small-scale atmospheric disturbances such as tropical storms — despite how prominently these phenomena feature on weather maps. Scientists therefore need to infer the effect of global warming on storm activity from general patterns of atmospheric circulation.What are the models saying?

For example, hurricane researcher Kerry Emanuel of the Massachusetts Institute of Technology in Cambridge has used³ a technique to simulate large numbers of tropical cyclones in climate models. When applied to scenarios of historical and future climate described by six state-of-the-art climate models, his method predicted that both the frequency and intensity of tropical cyclones will increase during the twenty-first century in all tropical ocean regions, except the southwestern Pacific. Emanuel’s study was published too late for inclusion in the latest IPCC report.

The Role of Surface Oxygen in the Growth of Large Single-Crystal Graphene on Copper

Science

The growth of high-quality single crystals of graphene by chemical vapor deposition on copper (Cu) has not always achieved control over domain size and morphology, and the results vary from lab to lab under presumably similar growth conditions. We discovered that oxygen (O) on the Cu surface substantially decreased the graphene nucleation density by passivating Cu surface active sites. Control of surface O enabled repeatable growth of centimeter-scale single-crystal graphene domains. Oxygen also accelerated graphene domain growth and shifted the growth kinetics from edge-attachment–limited to diffusion-limited. Correspondingly, the compact graphene domain shapes became dendritic. The electrical quality of the graphene films was equivalent to that of mechanically exfoliated graphene, in spite of being grown in the presence of O.

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F.D.A. Ruling Would All but Eliminate Trans Fats

The Food and Drug Administration proposed measures on Thursday that would all but eliminate artery-clogging, artificial trans fats from the food supply, the culmination of three decades of effort by public health advocates to get the government to take action against them.

Artificial trans fats — a major contributor to heart disease in the United States — have already been substantially reduced in foods. But they still lurk in many popular products, like frostings, microwave popcorn, packaged pies, frozen pizzas, margarines and coffee creamers. Banning them completely could prevent 20,000 heart attacks and 7,000 deaths from heart disease each year, the F.D.A. said.

“This is the final slam dunk on the trans fat issue,” said Barry Popkin, a nutrition epidemiologist at the University of North Carolina, Chapel Hill.

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Reward-based hypertension control by a synthetic brain–dopamine interface

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Essential activities such as feeding and reproduction as well as social, emotional, and mental behavior are reinforced by the brain’s reward system. Pleasure status directly correlates with dopamine levels released in the brain. Because dopamine leaks into the bloodstream via the sympathetic nervous system, brain and blood dopamine levels are interrelated. We designed a synthetic dopamine sensor-effector device that enables engineered human cells, insulated by immunoprotective microcontainers and implanted into the abdomen of mice, to monitor blood-dopamine levels and drive dopamine-dependent secretion of product proteins in pleasure situations associated with palatable food, drugs, or sexual arousal. Hypertensive animals treated with this device, which produces a clinically licensed antihypertensive peptide, had their high blood pressure corrected when exposed to sexual arousal.

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