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6 November 2009

Diets High In Sodium And Artificially Sweetened Soda Linked To Kidney Function Decline

Individuals who consume a diet high in sodium or artificially sweetened drinks are more likely to experience a decline in kidney function, according to two papers being presented at the American Society of Nephrology's annual meeting in San Diego, California.

Julie Lin MD, MPH, FASN and Gary Curhan, MD, ScD, FASN of Brigham and Women's Hospital studied more than 3,000 women participating in the Nurses' Health Study to identify the impact of sodium and sweetened drinks on kidney function.

"There are currently limited data on the role of diet in kidney disease," said Dr. Lin. "While more study is needed, our research suggests that higher sodium and artificially sweetened soda intake are associated with greater rate of decline in kidney function."

The first study, "Associations of Diet with Kidney Function Decline," examined the influence of individual dietary nutrients on kidney function decline over 11 years in more than 3,000 women participants of the Nurses' Health Study. The authors found that "in women with well-preserved kidney function, higher dietary sodium intake was associated with greater kidney function decline, which is consistent with experimental animal data that high sodium intake promotes progressive kidney decline."

The second study, also conducted by Dr. Lin and Dr. Curhan, "Associations of Sweetened Beverages with Kidney Function Decline," examined the influence of sugar-sweetened and artificially sweetened beverages on kidney function decline in the same group of Nurses' Health Study participants. An analysis of the nationally representative NHANES III participants had previously reported an association between sugar-sweetened soda and urinary protein, but data on kidney function change was not available. This investigation reported "a significant two-fold increased odds, between two or more servings per day of artificially sweetened soda and faster kidney function decline; no relation between sugar-sweetened beverages and kidney function decline was noted" said Dr. Lin. This association persisted even after the study authors accounted for age, caloric intake, obesity, high blood pressure, diabetes, cigarette smoking, physical activity, and cardiovascular disease. The mechanisms for kidney decline in the setting of high intake of artificial sweetenters have not been previously studied and deserve further investigation.

The study participants were older Caucasian women and the authors note that the findings may not be directly applicable to men or people of other ethnicities.

5 November 2009

This Is Your Brain On Fatty Acids: Scientists Discover Lipid May Be Vital To Learning

Saturated fats have a deservedly bad reputation, but Johns Hopkins scientists have discovered that a sticky lipid occurring naturally at high levels in the brain may help us memorize grandma's recipe for cinnamon buns, as well as recall how, decades ago, she served them up steaming from the oven.

The Hopkins team, reporting Oct. 29 in Neuron, reveals how palmitate, a fatty acid, marks certain brain proteins -- NMDA receptors -- that need to be activated for long-term memory and learning to take place. The fatty substance directs the receptors to specific locations in the outer membrane of brain cells, which continually strengthen and weaken their connections with each other, sculpting and resculpting new memory circuits.

Moreover, the researchers report, this fatty modification is a reversible process, with some sort of on-off switch, offering possibilities for manipulating it to enhance or even, perhaps, erase memory.

"Before now, no one knew that NMDA receptors change in response to the addition of palmitate," says Richard Huganir, Ph.D., professor and director of the Solomon H. Snyder Department of Neuroscience at Johns Hopkins.

Scientists have known that a brain signaling chemical called glutamate normally activates NMDA receptors, allowing two neurons to communicate with one another. However, they were less certain what allowed this receptor to assemble properly, or what caused it to make its way to the synapse, the specialized part of nerve cells where communication takes place.

The discovery emerged from work with live neurons in a dish, to which the scientists first fed radioactive palmitate, then separated out the NMDA receptors. By tracking radioactivity on X-ray film, they were able to determine that the fat had attached to the NMDA receptors.

Next, the scientists put both normal and altered NMDA receptors into non-brain cells that don't normally manufacture their own NMDA receptors. By tracking the radioactive fat, they were able to determine where on the NMDA receptor the fat had attached.

Results showed that the NMDA receptor undergoes "dual palmitoylation," in two different regions, each of which plays a distinct role in controlling the fate of the receptor in neurons. When the fat attaches to the first region, it stabilizes the receptor on the surface of neurons. When the fat attaches to the second region, the receptors accumulate inside neurons, perhaps awaiting a signal to send them to synapses. The researchers suspect that this could be part of a quality control measure, assuring that all the Lego-like protein subunits of the receptor are put together properly.

"It is rapidly becoming clear that palmitate regulates not only NMDA receptors, but also other brain proteins at work during signaling across synapses," says Gareth Thomas, Ph.D., a Howard Hughes Medical Institute postdoctoral fellow at Hopkins.

The researchers suspect that if palmitoylation fails, the result would be learning and memory impairment because if NMDA receptors don't make their way to the synapses -- the specialized contact points between cells across which chemical messages flow -- then communication between neurons is compromised.

"This new modification of the NMDA receptor deepens our molecular understanding of how synapses are regulated and how memories might be formed. It also reveals new potential drug targets, such as the enzymes that add or remove the palmitate," Huganir says. "If we could shift the balance of the palmitoylation, then perhaps we could affect and enhance learning and memory."

Propolis Has Proved To Be A Product With Ability To Have Beneficial Effects For Health

Growing concerns about health has caused the scientific community to focus their interest on investigating functional foods which contribute to boosting the prevention and reduction of the risk of suffering from certain illnesses. The benefits of this product lies in its composition and, thus, its study, identification and subsequent extraction provides a useful tool which enables making high added-value products, given their high concentration of biologically active compounds.

Over the past 5 years, Neiker-Tecnalia, in collaboration with the Fundación Kalitatea, apicultural associations in the Autonomous Community of the Basque Country, honey producing plants and Basque governmental bodies, has undertaken R+D projects associated with the beekeeping sector. Various products derived from the beehive have been studied and propolis has proved to be a product having beneficial results for human health.

Propolis (Pro-before, Polis-city = defence of the city), is the resinous substance that bees gather from the leaf buds of trees and certain vegetables. The bee gathers this and transforms it in order to disinfect the beehive, seal cracks, build panels, as well as using it as a microbiocidal agent, disinfectant and also for embalming intruders otherwise difficult to expel due to their size. Propolis is, thus, directly responsible for guaranteeing the asepsis of the beehives, locations prone to developing viruses and bacteria, given their conditions of temperature and humidity.

Although the precise composition of propolis depends on the zone of beehive activity (climate, surrounding vegetation, and so on), as a rough guide, we can mention the following: resins and balsams (50-60%), waxes (20-25%), essential oils (5-10%), pollen (5%), others (minerals, enzymes, etc. 5%).

The fraction of resins and balsams is the one that contains most of the biologically active compounds, mainly phenolic ones derived from the vegetable kingdom and having proven pharmacological abilities. Due to the great number of active ingredients present, tincture (alcoholic extract) of propolis is well-known and used for its therapeutic properties, principally for its stimulant action on the organism's defence system. Notable amongst its properties are its antioxidant and anti-microbial action, its activity as a stimulant and its healing, analgesic, anaesthetic and anti-inflammatory activity.

The study of the biological activity of this product was undertaken following two lines of work: (a) a study of the antioxidant activity and (b) a study of the anti-microbial action.

Antioxidant properties

The antioxidant activity trials provided knowledge about the capacity of the product under study (propolis) for neutralising free radicals. These radicals represent damaged molecules, generated both in endogenous and exogenous ways, capable of causing damage at cell level, and causing the onset of future degenerative illnesses, such as cancer, Alzeheimer, and so on.

A diet rich in antioxidants minimises the risk of the onset of this kind of illness, and so the evaluation of the antioxidant activity of a product when establishing its preventative potential is of great interest.

This type of trial involves the artificial generation of free radicals in the laboratory and which are subsequently made to react with the sample to which the antioxidant properties are attributed, in order to estimate their capacity for neutralisation. To this end, three spectrophotometric techniques were applied.

Antimicrobial properties

The test for anti-microbial action enables the evaluation of the inhibition exercised on the growth of certain microorganisms by the product under study. The MIC (Minimum Inhibitory Concentration) methodology involved the diffusion of the substance under study in a medium in which the growth of the microorganisms is optimum. If the substance diffused has a capacity to impede the growth of the chosen microorganism, a halo will appear around the central point where the product has been deposited. Otherwise, the medium will remain unaltered.

To carry out this trial the strains were activated in an optimum medium containing the necessary nutrients for the growth/development of the microorganism. When growth reached the Macfarlane index, close to 0.5, agar was added and seeded in rectangular plaques. Once solidified, the plaques were drilled and, by means of templates, various concentrations of propolis (0.1-50%) were deposited. All the concentrations were tested in triplicate. The plaques were incubated at 37 ºC and, after this, the presence/absence of the halos of inhibition was detected and which provided a visualised measurement of the inhibition exercised by the propolis on the growth of the microorganism used. These halos of inhibition were measured with calibres and the values obtained were extrapolated using as a template a plaque seeded with various concentrations of phenol (1-10%), which has a powerful biocide activity.

3 November 2009

Low vitamin D tied to heart, stroke deaths

NEW YORK (Reuters Health) - Low vitamin D levels in the body may be deadly, according to a new study hinting that adults with lower, versus higher, blood levels of vitamin D may be more likely to die from heart disease or stroke.

Vitamin D is an essential vitamin mostly obtained from direct sunlight exposure, but also found in foods and multivitamins.

Dr. Annamari Kilkkinen, at the National Institute for Health and Welfare in Helsinki, Finland, and colleagues compared blood levels of vitamin D and deaths from heart disease or stroke over time in 2,817 men and 3,402 women in Finland.

At enrollment, participants were just over 49 years old on average, and had no indicators of cardiovascular disease, the researchers note in the American Journal of Epidemiology.

During follow-up of about 27 years on average, 640 of the participants (358 men) died from heart disease and another 293 (122 men) died from stroke.

Compared with participants' with the highest vitamin D, those with the lowest had 25 percent higher risk of dying from heart disease or stroke, Kilkkinen noted in an email to Reuters Health.

There was a "particularly striking association" between vitamin D levels and stroke deaths, the researcher noted, in that having the lowest vitamin D seemed to confer "twice the risk," compared with having the highest vitamin D.

Allowing for age, gender, and other demographic factors, plus alcohol intake, smoking, physical activity, and season in which vitamin D levels were obtained did not significantly alter these associations.

In this study, vitamin D levels were "substantially lower" than levels thought to be sufficient, and "somewhat lower" than those reported in previous studies in other European and American populations.

However, there is no "absolute consensus" as to what the optimal range of vitamin D should be, the investigators note. Also, it's not known whether low vitamin D actually causes increased risk for heart disease or stroke. Clearly, further study is needed, they conclude.

Exercise keeps dangerous visceral fat away a year after weight loss, finds UAB study

A study conducted by exercise physiologists in the University of Alabama at Birmingham (UAB) Department of Human Studies finds that as little as 80 minutes a week of aerobic or resistance training helps not only to prevent weight gain, but also to inhibit a regain of harmful visceral fat one year after weight loss.

The study was published online Oct. 8 and will appear in a future print edition of the journal Obesity.

Unlike subcutaneous fat that lies just under the skin and is noticeable, visceral fat lies in the abdominal cavity under the abdominal muscle. Visceral fat is more dangerous than subcutaneous fat because it often surrounds vital organs. The more visceral fat one has, the greater is the chance of developing Type 2 diabetes and heart disease.

In the study, UAB exercise physiologist Gary Hunter, Ph.D., and his team randomly assigned 45 European-American and 52 African-American women to three groups: aerobic training, resistance training or no exercise. All of the participants were placed on an 800 calorie-a-day diet and lost an average 24 pounds. Researchers then measured total fat, abdominal subcutaneous fat and visceral fat for each participant.

Afterward, participants in the two exercise groups were asked to continue exercising 40 minutes twice a week for one year. After a year, the study's participants were divided into five groups: those who maintained aerobic exercise training, those who stopped aerobic training, those who maintained their resistance training, those who stopped resistance training and those who were never placed on an exercise regimen.

"What we found was that those who continued exercising, despite modest weight regains, regained zero percent visceral fat a year after they lost the weight," Hunter said. "But those who stopped exercising, and those who weren't put on any exercise regimen at all, averaged about a 33 percent increase in visceral fat.

"Because other studies have reported that much longer training durations of 60 minutes a day are necessary to prevent weight regain, it's not too surprising that weight regain was not totally prevented in this study," Hunter said. "It's encouraging, however, that this relatively small amount of exercise was sufficient to prevent visceral fat gain."

The study also found that exercise was equally effective for both races.

2 November 2009

Cell Phones on Hip May Weaken Bone

Study Suggests Link Between Bone Weakness and Wearing a Cell Phone on the Hip

Oct. 27, 2009 -- Early research suggests that wearing a cell phone on your hip may weaken the area of the pelvis widely used for bone grafting.

Using an X-ray technique used in the diagnosis and monitoring of patients with osteoporosis, researchers from Turkey's Suleyman Demireli University measured pelvic bone density in 150 men who regularly carried their cell phones attached to their belts.

The men carried their phones for an average of 15 hours each day; they had used cell phones for an average of six years.

The researchers found that bone mineral density was slightly less on the side of the pelvis where the mobile phones were carried than on the side that was not in contact with the phones.

The difference was not statistically significant and fell far short of approaching bone density reductions seen in people with osteoporosis.

But the findings raise the possibility that bone density could be adversely affected by electromagnetic fields emitted by cell phones, researcher Tolga Atay, MD, and colleagues note in a news release.

The men in the study were relatively young -- their average age was 32 -- and the researchers hypothesize that bone loss may be more significant in older people with a greater risk for osteoporosis.

The study appears in the September issue of the Journal of Craniofacial Surgery.

It is among the first to suggest that close-proximity, long-term exposure to mobile phones may weaken bones, and the researchers stress that their findings are preliminary.

Second Opinion
Frank Barnes, PhD, who is a distinguished professor of electrical and computer engineering at the University of Colorado, Boulder, tells WebMD that he knows of no other research examining the impact of cell phone exposure on bone density.

Barnes chaired a National Research Council (NRC) committee asked by the FDA to report on the research evaluating cell phone safety.

He points out that electromagnetic waves have been used experimentally to promote bone growth in people with broken bones that would not heal.

Electromagnetic wave treatment has also been found to strengthen bone in research involving patients with osteoporosis.

But Atay and colleagues point out that these studies involved very low electromagnetic wave frequencies of 15 to 72 Hz, while cell phones typically have frequencies of between 900 to 1,800 MHz.

The NRC committee chaired by Barnes published its report in January 2008, concluding that more research is needed to determine if cell phone use is associated with any long-term health problems.

"It is clear that using a cell phone poses no immediate risk," Barnes tells WebMD. "But it may take many years to have the answers we are looking for with regard to long-term risk."

Barnes says there has been very little research aimed at determining whether radiofrequency waves emitted by cell phones pose a risk to specific groups, such as children, adolescents, and pregnant women and their fetuses.

EFSA affirms omega-3 can benefit baby brains and eyes

The European Food Safety Authority (EFSA) has confirmed that the omega-3 fatty acids, DHA and ALA, can benefit eye and cognitive development in babies.

Responding to the public comment period for Merck Selbstmedikation GmbH’s article 14 cognitive development claim that was rejected in March, EFSA affirmed its original stance that there was no need for additional supplementation of DHA (docosahexaenoic acid) and ALA (alpha-linolenic acid) because it already existed at adequate levels in the diet.

It supported their role in foetal and newborn eye and brain development but said there was an adequate supply in breast milk.

“DHA has a structural and functional role in the brain and retina and maternal DHA intake can contribute to the early development of the eye and normal cognitive development in the foetus and the brain-fed infant,” wrote Dr Juliane Kleiner, head of the DNA panel.

But in regard to the need for supplementation she added: “…while DHA can be synthesised in the human body from its precursor essential fatty acid ALA to a certain extent, the human foetus appears to be largely dependent on placental transfer of DHA from the mother derived either from her diet, from synthesis or from stores in adipose tissue. The Panel also noted that most DHA is provided to the breast-fed infant via breast milk in which the DHA concentration is dependent both on maternal dietary intake and maternal DHA stores, while the contribution by synthesis is low.”

“All these factors, and the fact DHA supplementation was administered in most studies in addition to background diets already providing ALA and DHA in unspecified amounts, may have accounted for the insufficient evidence for a causal relationship between maternal supplementation with DHA and visual and cognitive benefits in their offspring.”