Hunger triggered off by fatty foods:

Not empty stomach

New research led by the University of Cincinnati (UC) suggests that the hunger hormone ghrelin is activated by fats from the foods we eat "not those made in the body" in order to optimise nutrient metabolism and promote the storage of body fat.

The findings, the study's author says, turn the current model about ghrelin on its head and point to a novel stomach enzyme (GOAT) responsible for the ghrelin activation process that could be targeted in future treatments for metabolic diseases.

The laboratory study, led by Matthias Tschop MD, UC associate professor of psychiatry and internal medicine, was published in the journal Nature Medicine.

Ghrelin is a hormone that was believed to accumulate during periods of fasting and is found in the body in high concentrations just before meals. It is dubbed the "hunger hormone" because it has been shown that administration of pharmacological (scientifically studied or researched) doses acts in the brain to stimulate (to activate) hunger and increase food intake in animal models and humans.The ghrelin hormone is unique in that it requires acylation (the addition of a fatty acid) by a specific enzyme (ghrelin O-acyl transferase, or GOAT) for activation. Originally it was assumed that the fatty acids attached to ghrelin by GOAT were produced by the body during fasting. The new data by Tschop and his team suggests that the fatty acids needed for ghrelin activation actually come directly from ingested dietary fats. In a departure from an earlier model that was upheld for nearly a decade, Tschop says, it appears that the ghrelin system is a lipid sensor in the stomach that informs the brain when calories are available, "giving the green light to other calorie-consuming processes such as growing.

Tschop and his team used mouse models to test the effects of over expressing the GOAT enzyme, or "knocking it out." They found that, when exposed to a lipid-rich diet, mice without GOAT accumulated less fat than normal mice, while those with over-expressed GOAT accumulated more fat mass than normal mice.

"When exposed to certain fatty foods, mice with more GOAT gain more fat," says Tschop. "Mice without GOAT gain less fat since their brain does not receive the 'fats are here, store them' signal."

Tschop says that although his study can't be immediately extrapolated (considered as valid) to humans, recent human studies at the University of Virginia measured (separately) active and inactive ghrelin concentrations.

Those studies showed that during fasting, active ghrelin levels were flat, but during the presence of fat from foods, ghrelin levels peaked with meals as previously described. Tschop says these human studies support the new model for ghrelin.

"Our GOAT studies in mice offer an explanation of what could have been happening during the longer fasting periods in these human studies," Tschop adds. "Without dietary fats, ghrelin peaks remain inactive and don't affect storage of fat.

Courtesy: Health and Medicine

Drinking water from air humidity

Not a plant to be seen, the desert ground is too dry. But the air contains water, and research scientists have found a way of obtaining drinking water from air humidity. The system is based completely on renewable energy and is therefore autonomous (able to function on its own).

Cracks permeate (spread throughout) the dried-out desert ground, the landscape bears testimony to the lack of water. But even here, where there are no lakes, rivers or ground water, considerable quantities of water are stored in the air. In the Negev desert in Israel, for example, annual average relative air humidity is 64 per cent" in every cubic metre of air there are 11.5 millilitres of water.

Research scientists at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart working in conjunction (jointly) with their colleagues from the company Logos Innovation have found a way of converting this air humidity autonomously and decentraly into drinkable water. "The process we have developed is based exclusively on renewable energy sources such as thermal solar collectors and photovoltaic cells, which makes this method completely energy-autonomous. It will therefore function in regions where there is no electrical infrastructure," says Siegfried Egner, head of department at the IGB. The principle of the process is as follows: hygroscopic brine 'saline solution which absorbs moisture' runs down a tower-shaped unit and absorbs water from the air. It is then sucked into a tank a few meters off the ground in which a vacuum (space completely empty of all substances) prevails. Energy from solar collectors heats up the brine, which is diluted by the water it has absorbed. Because of the vacuum, the boiling point of the liquid is lower than it would be under normal atmospheric pressure. This effect is known from the mountains: as the atmospheric pressure there is lower than in the valley, water boils at temperatures distinctly below 100 degrees Celsius. The evaporated, non-saline water is condensed and runs down through a completely filled tube in a controlled manner. The gravity of this water column continuously produces the vacuum and so a vacuum pump is not needed. The reconcentrated brine runs down the tower surface again to absorb moisture from the air.

"The concept is suitable for various sizes of installation.

Courtesy: Science Daily

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