Sunday, October 09, 2011

New study suggests inflammation may not be cause of obesity-type 2 diabetes link

For years, it has been assumed that obesity led to type 2 diabetes by causing inflammation, which was thought to change the way the body reacts to the effects of insulin. However, a new study suggests that this hypothesis may need an update.

Researchers from Children’s Hospital Boston reported in the journal Nature Medicine that inflammation actually activates two different proteins that play key roles in stablizing blood sugar levels. Without the presence of inflammation, these proteins remain dormant.

The findings suggest an important new role for inflammation in the body. Rather than being the cause of health problems like type 2 diabetes, heart disease and certain cancers, it may actually be a helpful reaction to other conditions in the body that are the real cause of disease...

Cold mice might be skewing weight-loss drug studies

Animals and people burn calories in an effort to keep warm, and room temperature may be affecting the testing and development of weight-loss drugs, says University of Alabama at Birmingham researcher Daniel Smith, Ph.D.

Smith, an instructor in the Department of Nutrition Sciences, received a 2011 Early-Career Research Grant from The Obesity Society for his proposal to examine the effect of room temperature on obesity-related drug effects in mice.

“More than 90 percent of weight-loss drugs that show promising results in lab tests fail to reach approval for treatment in humans,” said Smith. “There appears to be a translation gap from the bench to the market. I think the temperature used in animal research facilities may be part of the reason.”

Smith noted that most animals are tested in rooms where the temperature is near 22 degrees Celsius (72F), which is comfortable for most adult humans. However, that temperature is cold for mice, which have to eat more to elevate their metabolic rate to meet the constant, cold stress.

“If you raise the temperature to 30 degrees Celsius, that puts the mice in their thermo-neutral zone or a comfortable temperature for them, mimicking more closely what humans experience in modern daily life,” said Smith.

Smith will test a handful of weight-loss drugs in a group of mice housed at 22 degrees Celsius and another group at 30 degrees Celsius. Food intake, body weight and body composition will be measured to determine drug-related, weight-loss effects in the two temperatures. He said this study could be an important turning point for obesity researchers using animal models.

“This could change the models of pre-clinical drug testing,” said Smith...

Parents' weight affects children, study shows

Overweight parents are more likely to have children who are obese which could lead to the need for weight loss surgery, according to a new study.

Thinner children are therefore more likely to come from slimmer families, researchers at University College London (UCL) have found through a national health survey for England.

Published in the Archives of Pediatrics & Adolescent Medicine, the study found that there is a strong association between children's and parents' body size.

When both parents were in the thinner half of the healthy weight range, the chance of the child being thin was 16.2 per cent, compared with 7.8 per cent when both parents were in the upper half of range.

In comparison, 5.3 per cent of children with two overweight parents are likely to be thin.

Lead author Dr Katriina Whitaker, UCL epidemiology and public health specialist, commented: "We know from other studies that children's weights are correlated with those of their parents, but previous research has tended to focus on obesity rather than the other end of the spectrum."

A further study published in Obesity suggested that green tea could decrease the risk of obesity after lab tests on mice showed positive results...

Carbs may suppress fat absorption and accumulation: Animal data

Dietary fructooligosaccharides – carbohydrates with established prebiotic activity – may suppress high-fat diet-induced body fat accumulation, and inhibit intestinal absorption of dietary fats, say researchers.

Writing in the journal BioFactors, researchers investigated the effects of fructooligosaccharides (FOS) on the development of obesity, using two experiments in rats and mice. They found that body weight and percent body fat were lower in mice fed FOS than in controls, whilst rats receiving an oral dose of FOS were reported to have suppressed elevation of plasma triglycerides.

“We have shown that a low dose of dietary FOS suppressed weight gain, accumulation of visceral adipose [fat] tissue, and the increase in liver triglycerides resulting from feeding a high-fat ‘western’ diet ... while fat excretion increased,” reported the authors, led by Yuko Nakamura from the Food and Health R&D Laboratories at the Japanese pharmaceutical company Meiji Seika Kaisha.

“These results suggest that FOS may prevent fat accumulation by inhibiting intestinal absorption of dietary fat in a high-fat ‘western’ diet,” added the researchers...

Discover Key Protein Responsible for Fat Storage

UC Davis Health System researchers have discovered that a protein called galectin-12 plays a key role in fat storage, a finding that could lead to improvements in treating obesity and diabetes. The researchers found that without the ability to make the protein, mice used in their research investigation stored 40 percent less body fat and had increased fat metabolism and decreased insulin resistance.

"This study for the first time demonstrates the importance of a galectin in energy metabolism," said Fu-Tong Liu, distinguished professor and chair of the UC Davis Department of Dermatology, and senior author on the paper.

The findings, published online this week in the early edition of the Proceedings of the National Academy of Sciences, point to galectin-12 as a potential target for the treatment of obesity and diabetes in humans. The breakdown and storage of fat in the body are both tightly controlled processes that involve numerous chemical signals, Liu said.

"In this case, galectin-12 seems to be signaling to fat cells that its time to conserve rather than burn energy," he said. "If we can interrupt that signal, we have a chance at improving fat metabolism and reducing insulin resistance in patients with obesity and type 2 diabetes."

Obesity is the number-one predictor for the development of diabetes, a leading cause of death and disability in the United States. An estimated 24 million Americans have the disease. Between 90 and 95 percent of them have type 2 diabetes, and about 80 percent of people with type 2 diabetes are overweight or obese.

In its early stages, type 2 diabetes is characterized by insulin resistance. The pancreas is producing insulin, but for unknown reasons the body cannot use the insulin effectively. After several years, insulin production decreases, glucose builds up in the blood and the body cannot make efficient use of its main source of fuel. People with advanced diabetes may experience blindness, require limb amputations or suffer fatal organ failure.

In order to discover potential treatments for type 2 diabetes, Liu and his UC Davis colleagues have been working to understand the chemical signals involved in normal energy metabolism and storage. They isolated and cloned the galectin-12 gene 10 years ago. Since then, their studies have shown that the gene is preferentially expressed in fat cells, and that its expression is required for fat-cell differentiation. To enable a focus on specific biological mechanisms associated with galectin-12, the researchers worked with the UC Davis Mouse Biology Program to obtain genetically customized mice that have had individual genes systematically turned off or "knocked out."

"We decided to create the galectin-12 knockout mice to further clarify the function of this protein in animals," said Ri-Yao Yang, associate project scientist...

Gene clue to diabetes sufferers

Scientists have identified a gene that could explain why some people are more susceptible than others to diabetes.

The gene, found in tests on obese mice, controls a protein called tomosyn-2 which acts as a brake on insulin secretion from the pancreas, the researchers also discovered.

Insulin is made and released by beta cells in the pancreas and regulates blood sugars. Those with type 1 diabetes have too little insulin, while those with type 2 are insulin-resistant - both conditions potentially causing serious health problems if they are not treated.

Alan Attie, of the University of Wisconsin-Madison, who led the study, said: "It's too early for us to know how relevant this gene will be to human diabetes, but the concept of negative regulation is one of the most interesting things to come out of this study and that very likely applies to humans."

The researchers studied obese mice as it takes more insulin to lower glucose for an obese person than someone of a healthy weight...

Green Tea May Help You Lose Weight

Drinking green tea can slow down weight gain by limiting the amount of fat absorbed by the body, the Daily Mail reported Wednesday.

In a new study, Penn State University researchers found that a compound in the herbal tea slowed down weight gain in mice.

Crucially, the mice were already obese at the start of the experiment. This makes the findings more relevant to humans because people often consider dietary changes only when they notice problems associated with obesity, the researchers said...

Scientists identify genes involved in storing fat

Researchers funded by the Wellcome Trust have identified several genes in fat tissue that may lead us to retain fat unnecessarily in the body. The study, using a mouse model, may explain why some people carry more weight than others even when they have similar diets because of genes that encourage fat storage.

Scientists at the University of Edinburgh compared fat tissue from mice that had been selectively bred for many generations to be increasingly fat or thin, and as a result had acquired weight-related genes. The research, published in the journal ’PLoS One’, cross-referenced thousands of genes and pinpointed genes that prevented the breakdown of fat, which were more prevalent in the fat tissue of the overweight mice than in the fat tissue of the lean mice.

Mice were then bred from one overweight parent and one lean parent. Those among the offspring that were born overweight were found to have the same active genes as the fatter parent mice - an indication that hereditary factors play a part in fat storage and can increase the likelihood of putting on weight.

The research also found that the thin offspring had an added protection against weight gain. When both sets of mice were given fatty foods, the thin offspring seemed able to break down fatty tissue more easily than the heavier mice, suggesting they had inherited ’lean genes’...

Fat content in mice affected by environment

A recent study found that mice living in socially enriching environments converted a greater portion of their energy-storing white fat to energy-burning brown fat, losing weight despite their increased caloric intake. These findings reinforce how social and physical environments can impact animal metabolisms.

Adipose tissue, commonly known as fat, comes in two types: white and brown. White fat, which constitutes as much as 20 percent of the body weight in men and 25 percent of the body weight in women, serves to store excess energy, cushion organs and maintain body temperature. Brown fat, which is especially abundant in newborns and hibernating mammals, expends energy to generate heat. Increases in white fat and brown fat concentrations are associated with weight gain and loss, respectively.

Functional differences between white and brown fat are predicted by differences in structure. White adipocytes contain a single, large lipid droplet that occupies most of the cell volume. In contrast, brown adipocytes contain numerous small droplets, more iron-containing mitochondria, which explains the characteristic brown color, and more capillaries to deliver greater amounts of oxygen.

While brown fat is best known for its role in insulating infants, scientists found that active brown fat is also present in adults. In addition, cold exposure and activation of the sympathetic nervous system drives the production of more brown fat. The new study, whose results are published in the September issue of Cell Metabolism, suggests that an engaging environment can provide another, perhaps more effective means to increase brown fat.

According to Lei Cao of The Ohio State University, the typical laboratory mouse leads what might be considered a "couch potato" lifestyle. Lab mice are given free access to food and water, as well as a few potential playmates. However, they are not given much else to do.

In the enriched environment, mice live in groups of 15 to 20. They are given more space as well as exercise wheels, mazes and toys. After four weeks in the enriched environment, the mice's abdominal fat decreased by 50 percent...