Wednesday, December 29, 2010

Honey before bedtime improves brain function, mental acuity

Sleep debt or chronic partial sleep deprivation from poor quality sleep has been shown to have a detrimental effect on overall energy metabolism in the body. The toxic interaction of impaired energy metabolism and chronic partial sleep loss is the underlying cause of the reduction in melatonin and the loss of brain function as we age. Failure to provide sufficient energy for the brain during sleep has a significant adverse effect on brain metabolism and on memory and learning.
Ironically, the most severe negative effect on brain energy provision occurs from chronic increased food consumption and the resultant excessive insulin production that follows. Excess insulin in the central nervous system has a profound negative influence on brain metabolism and on memory and learning. Hyperinsulinism prevents glucose uptake into the brain causing partial brain starvation. Our brain is actually starving during periods of excess energy availability.
Insulin also inhibits an enzyme in the brain which allows the accumulation of glutamate in the synaptic space between brain neurons. This leads to irreversible damage of nerve cells in the brain and deterioration of brain function.
Consuming honey before bedtime reduces the release of stress hormones and maximizes the production and release of melatonin, a hormone which is also known as the “learning hormone.” Overproduction of stress hormones night after night inhibit the release of melatonin. When melatonin is produced normally, it inhibits the negative effects of too much insulin in the brain.
Quality sleep which is critical for memory consolidation and vital in human learning may therefore be achieved by a simple strategy of consuming a tablespoon of honey before bedtime. This strategy optimizes recovery physiology, reduces chronic overproduction of adrenal stress hormones that inhibit melatonin, and produces the exact metabolic environment required for the release of melatonin, growth hormone and IGF-1, the key hormones of memory consolidation and learning.

More signs lung cancer screening could save lives

More research is suggesting that heavy smokers may benefit from screening for lung cancer, to detect tumors in their earliest stages.
A new study finds that regular smokers who received three-dimensional X-rays to look for the presence of early tumors had a significantly lower risk of dying over a 10-year period.
The results are in keeping with those of a much larger study published last month, which showed that these 3-D X-rays, or CT scans, reduced the death rate among 53,000 current and former heavy smokers by 20 percent compared with screening using regular chest X-rays. That previous finding was "very good news in the field," said Dr. Bruce Johnson of the Dana Farber Cancer Institute, who treats lung cancer patients and reviewed the results for the news agency.
This latest study, published in the journal Lung Cancer, looked at death rates in a different, smaller population of heavy smokers, and estimated that those who received up to two CT scans would have between a 36 and 64 percent lower risk of dying, compared to those who went unscreened.
The data are "consistent" with earlier studies but there are still many issues to resolve regarding lung cancer screening, Johnson said.
For one, scientists haven't yet worked out how often to screen people, and when to start. It is not clear when or how guidelines for lung cancer screening could be drawn up, and until they are, insurers including government programs such as Medicare are unlikely to pay the average $300 cost of a scan.
Furthermore, an April study showed that 21 percent of a patient's initial lung CT scans show suspicious lesions that turn out not to be cancer, but lead to needless invasive follow-up procedures and radiation exposure, as well as stress and anxiety for patients and their families.
The high so-called "false positive" rate is an issue, said Dr. James Hanley of McGill University, who also reviewed the findings for the British news agency, but many mammograms also find lesions that turn out to be benign. And for lung cancer, doctors know there is a high false-positive rate and have a set protocol to follow in order to determine which lesions are dangerous, added Johnson.

Lung cancer kills 1.2 million people a year globally and it will kill 157,000 people in the United States alone this year, according to the American Cancer Society.

Tobacco use accounts for some 85 percent of lung cancer cases in the U.S., and one estimate puts a smoker's lifetime absolute risk of developing lung cancer between 12 percent and 17 percent. Five-year survival rates for lung cancer are low.

In recent years, CT scans, in particular, have been promoted by some hospitals and advocacy groups for lung cancer screening, even though studies had not yet shown definitively whether such screening saves lives.

In 2006, Dr. Claudia Henschke, currently based at Mount Sinai School of Medicine and Arizona State University, caused a stir when she published a study concluding that 80 percent of lung-cancer deaths could be prevented through widespread use of spiral CT.

Her ideas were controversial to start with, especially when other researchers found her work had been paid for by a tobacco company.

In the current study, funded in part by manufacturers of CT scanners (along with government and other sources), Henschke and her colleagues compared outcomes for nearly 8,000 smokers and former smokers who volunteered to undergo CT scans to outcomes in two sets of people with smoking histories who were not scanned.

The three groups of people had some important differences, such as in average age and how long and heavily they had smoked, so the researchers had to use mathematical tools to try to eliminate the influence of those differences, said Hanley. For instance, to compare death rates, the researchers tracked how many people died among those who were screened, then pulled out all the people with similar underlying characteristics in the other two groups and looked at their death rates, Hanley explained.

A total of 64 people died in the screened population, the authors report -- but applying the death rate among people with the same underlying characteristics in one of the unscreened populations, they estimated that the number of deaths would have been 100. This translates into a 36 percent lower risk of dying among the screened population.
Applying the same methods to the other unscreened population, the authors estimated that screening was associated with a 64 percent lower risk of dying.
Overall, research is suggesting that CT scans of people at risk of lung cancer might make a dent in cancer mortality, and it's possible that more frequent screening might make an even bigger dent, Hanley noted. "If screening is going to work, you've got to keep at it."

Friday, December 24, 2010

'Un-Growth Hormone' Increases Longevity, Researchers Find

A compound which acts in the opposite way as growth hormone can reverse some of the signs of aging, a research team that includes a Saint Louis University physician has shown. The finding may be counter-intuitive to some older adults who take growth hormone, thinking it will help revitalize them.
Their research was published in the Dec. 6 online edition of the Proceedings of the National Academy of Sciences.
 The findings are significant, says John E. Morley, M.D., study co-investigator and director of the divisions of geriatric medicine and endocrinology at Saint Louis University School of Medicine, because people sometimes take growth hormone, believing it will be the fountain of youth.
"Many older people have been taking growth hormone to rejuvenate themselves," Morley said. "These results strongly suggest that growth hormone, when given to middle aged and older people, may be hazardous."
The scientists studied the compound MZ-5-156, a "growth hormone-releasing hormone (GHRH) antagonist." They conducted their research in the SAMP8 mouse model, a strain engineered for studies of the aging process. Overall, the researchers found that MZ-5-156 had positive effects on oxidative stress in the brain, improving cognition, telomerase activity (the actions of an enzyme which protects DNA material) and life span, while decreasing tumor activity.
MZ-5-156, like many GHRH antagonists, inhibited several human cancers, including prostate, breast, brain and lung cancers. It also had positive effects on learning, and is linked to improvements in short-term memory. The antioxidant actions led to less oxidative stress, reversing cognitive impairment in the aging mouse.
William A. Banks, M.D., lead study author and professor of internal medicine and geriatrics at the University of Washington School of Medicine in Seattle, said the results lead the team "to determine that antagonists of growth hormone-releasing hormone have beneficial effects on aging."
The study team included as its corresponding author Andrew V. Schally, M.D., Ph.D., a professor in the department of pathology and division of hematology/oncology at the University of Miami Miller School of Medicine.

Placebos Work -- Even Without Deception

For most of us, the "placebo effect" is synonymous with the power of positive thinking; it works because you believe you're taking a real drug. But a new study rattles this assumption.
Researchers at Harvard Medical School's Osher Research Center and Beth Israel Deaconess Medical Center (BIDMC) have found that placebos work even when administered without the seemingly requisite deception.
 The study is published December 22 in PLoS ONE.
Placebos -- or dummy pills -- are typically used in clinical trials as controls for potential new medications. Even though they contain no active ingredients, patients often respond to them. In fact, data on placebos is so compelling that many American physicians (one study estimates 50 percent) secretly give placebos to unsuspecting patients.
Because such "deception" is ethically questionable, HMS associate professor of medicine Ted Kaptchuk teamed up with colleagues at BIDMC to explore whether or not the power of placebos can be harnessed honestly and respectfully.
To do this, 80 patients suffering from irritable bowel syndrome (IBS) were divided into two groups: one group, the controls, received no treatment, while the other group received a regimen of placebos -- honestly described as "like sugar pills" -- which they were instructed to take twice daily.
"Not only did we make it absolutely clear that these pills had no active ingredient and were made from inert substances, but we actually had 'placebo' printed on the bottle," says Kaptchuk. "We told the patients that they didn't have to even believe in the placebo effect. Just take the pills."
For a three-week period, the patients were monitored. By the end of the trial, nearly twice as many patients treated with the placebo reported adequate symptom relief as compared to the control group (59 percent vs. 35 percent). Also, on other outcome measures, patients taking the placebo doubled their rates of improvement to a degree roughly equivalent to the effects of the most powerful IBS medications.
"I didn't think it would work," says senior author Anthony Lembo, HMS associate professor of medicine at BIDMC and an expert on IBS. "I felt awkward asking patients to literally take a placebo. But to my surprise, it seemed to work for many of them."
The authors caution that this study is small and limited in scope and simply opens the door to the notion that placebos are effective even for the fully informed patient -- a hypothesis that will need to be confirmed in larger trials.
"Nevertheless," says Kaptchuk, "these findings suggest that rather than mere positive thinking, there may be significant benefit to the very performance of medical ritual. I'm excited about studying this further. Placebo may work even if patients knows it is a placebo."

Healing Ear Infections Faster Otolaryngologists Have A New Device For Inserting Ear Tubes

Otolaryngologists now usea stainless steel device to insert into the ear that provides an easier, safer and faster treatment for a common problem associated with earaches, chronic otitis media with effusion. The tiny device consists of a hollow rod with a collar that holds the tube in place, allowing the surgeon to insert the tube with one motion and suction out any residual fluid that might be in the middle ear space.
 Three out of four children fall victim to an ear infection by the time they're three years old, many of them during winter when viruses abound. Treating the common problem can be a tedious procedure, but a new device makes healing ears simple.
For years, Nancy Mazurianic has watched her son Tristen suffer from painful ear infections.
"It was awful," Nancy said. "You hate to see your kid in pain like that."
 For some patients, doctors insert tiny tubes inside the ears to ease pressure and fluid buildup and relieve pain. Multiple medical instruments are normally used for the procedure, putting delicate ears at risk for injury. "The skin is so thin in the ear canal that if you just touch it with an instrument, it will start to bleed," said Bradley Kesser, M.D., an otolaryngologist at the University of Virginia in Charlottesville, Va.
Now, otolaryngologists -- or ear, nose and throat specialists -- have a new tiny device that makes the procedure safer, easier and faster so there's less risk of injury.
"With a single instrument, we're able to insert the tube and suction out any residual fluid that might be in the middle ear space," Dr. Kesser said.
Under general anesthesia, doctors make a small incision in the eardrum. Then the new device, a hollow rod holding a tiny tube, is inserted into this small opening with one motion. The tube lets air in and drains any fluid out. Eventually, the tube falls out.
"We've devised an instrument to increase the reliability of ear tube insertion, increase its safety and potentially increase its speed," Dr. Kesser said.
Tristen's procedure was a success, and his mom is thrilled to see him pain-free.
"It's been just amazing," Nancy said. "He's been a happy little camper [and] never complains about the ears at all anymore."
Happy is a good thing to hear.
ABOUT EAR INFECTIONS: There are three main parts to the human ear: outer, middle and inner ear. The outer ear is the part you can see and opens into the ear canal leading to the middle ear. The middle ear is a closed, air-filled chamber, separated from the outer ear by the ear drum, and ventilated by the Eustachian tube. Sometimes the pressure in the middle ear becomes higher or lower than that in the outer ear, causing hearing loss, severe pain, and the accumulation of fluid in the middle ear. The inner ear contains the hearing nerve that leads to the brain. It detects sound vibrations and turns them into electrical nerve impulses, which the brain then interprets as sound.
PREVENTING EAR INFECTIONS: Chronic middle ear fluid is a condition known as otitis media with effusion (OME).When this condition becomes persistent, and antibiotics aren't effective, it is often treated with surgical insertion of ear ventilation tubes. More than 700,000 children undergo this procedure each year. But the tubes often fall out within four to seven months, and the patients may have a recurrence of the condition.

Sunday, December 12, 2010

A Swarm of Ancient Stars

We know of about 150 of the rich collections of old stars called globular clusters that orbit our galaxy, the Milky Way. A sharp new image of Messier 107, captured by the Wide Field Imager on the 2.2-metre telescope at ESO's La Silla Observatory in Chile, displays the structure of one such globular cluster in exquisite detail. Studying these stellar swarms has revealed much about the history of our galaxy and how stars evolve.
The globular cluster Messier 107, also known as NGC 6171, is a compact and ancient family of stars that lies about 21 000 light-years away. Messier 107 is a bustling metropolis: thousands of stars in globular clusters like this one are concentrated into a space that is only about twenty times the distance between our Sun and its nearest stellar neighbour, Alpha Centauri, across. A significant number of these stars have already evolved into red giants, one of the last stages of a star's life, and have a yellowish colour in this image.

Globular clusters are among the oldest objects in the Universe. And since the stars within a globular cluster formed from the same cloud of interstellar matter at roughly the same time -- typically over 10 billion years ago -- they are all low-mass stars, as lightweights burn their hydrogen fuel supply much more slowly than stellar behemoths. Globular clusters formed during the earliest stages in the formation of their host galaxies and therefore studying these objects can give significant insights into how galaxies, and their component stars, evolve.
Messier 107 has undergone intensive observations, being one of the 160 stellar fields that was selected for the Pre-FLAMES Survey -- a preliminary survey conducted between 1999 and 2002 using the 2.2-metre telescope at ESO's La Silla Observatory in Chile, to find suitable stars for follow-up observations with the VLT's spectroscopic instrument FLAMES (Fibre Large Array Multi-Element Spectrograph). Using FLAMES, it is possible to observe up to 130 targets at the same time, making it particularly well suited to the spectroscopic study of densely populated stellar fields, such as globular clusters.
M107 is not visible to the naked eye, but, with an apparent magnitude of about eight, it can easily be observed from a dark site with binoculars or a small telescope. The globular cluster is about 13 arcminutes across, which corresponds to about 80 light-years at its distance, and it is found in the constellation of Ophiuchus, north of the pincers of Scorpius. Roughly half of the Milky Way's known globular clusters are actually found in the constellations of Sagittarius, Scorpius and Ophiuchus, in the general direction of the centre of the Milky Way. This is because they are all in elongated orbits around the central region and are on average most likely to be seen in this direction.
Messier 107 was discovered by Pierre M├ęchain in April 1782 and it was added to the list of seven Additional Messier Objects that were originally not included in the final version of Messier's catalogue, which was published the previous year. On 12 May 1793, it was independently rediscovered by William Herschel, who was able to resolve this globular cluster into stars for the first time. But it was not until 1947 that this globular cluster finally took its place in Messier's catalogue as M107, making it the most recent star cluster to be added to this famous list.
This image is composed from exposures taken through the blue, green and near-infrared filters by the Wide Field Camera (WFI) on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile.

New Clues to How Earth, Moon, and Mars Formed

New Insights Into Formation of Earth, the Moon, and Mars:
New research reveals that the abundance of so-called highly siderophile, or metal-loving, elements like gold and platinum found in the mantles of Earth, the Moon and Mars were delivered by massive impactors during the final phase of planet formation over 4.5 billion years ago. The predicted sizes of the projectiles, which hit within tens of millions of years of the giant impact that produced our Moon, are consistent with current planet formation models as well as physical evidence such as the size distributions of asteroids and ancient Martian impact scars.
They predict that the largest of the late impactors on Earth -- at 1,500 to 2,000 miles in diameter -- potentially modified Earth's obliquity by approximately 10 degrees, while those for the Moon, at approximately 150-200 miles, may have delivered water to its mantle.
The team that conducted this study comprises solar system dynamicists, such as Dr. William Bottke and Dr. David Nesvorny from the Southwest Research Institute, and geophysical-geochemical modelers, such as Prof. Richard J. Walker from the University of Maryland, Prof. James Day from the University of Maryland and Scripps Institution of Oceanography, and Prof. Linda Elkins-Tanton, from the Massachusetts Institute of Technology. Together, they represent three teams within the NASA Lunar Science Institute (NLSI).
A fundamental problem in planetary science is to determine how Earth, the Moon, and other inner solar system planets formed and evolved. This is a difficult question to answer given that billions of years of history have steadily erased evidence for these early events. Despite this, critical clues can still be found to help determine what happened, provided one knows where to look.
For instance, careful study of lunar samples brought back by the Apollo astronauts, combined with numerical modeling work, indicates that the Moon formed as a result of a collision between a Mars-sized body and the early Earth about 4.5 billion years ago. While the idea that the Earth-Moon system owes its existence to a single, random event was initially viewed as radical, it is now believed that such large impacts were commonplace during the end stages of planet formation. The giant impact is believed to have led to a final phase of core formation and global magma oceans on both the Earth and Moon.
For the giant impact hypothesis to be correct, one might expect samples from the Earth and Moon's mantle, brought to the surface by volcanic activity, to back it up. In particular, scientists have examined the abundance in these rocks of so-called highly siderophile, or metal-loving, elements: Re, Os, Ir, Ru, Pt, Rh, Pd, Au. These elements should have followed the iron and other metals to the core in the aftermath of the Moon-forming event, leaving the rocky crusts and mantles of these bodies void of these elements. Accordingly, their near-absence from mantle rocks should provide a key test of the giant impact model.
However, as described by team member Walker, "The big problem for the modelers is that these metals are not missing at all, but instead are modestly plentiful." Team member Day adds, "This is a good thing for anyone who likes their gold wedding rings or the cleaner air provided by the palladium in their car's catalytic convertors."
A proposed solution to this conundrum is that highly siderophile elements were indeed stripped from the mantle by the effects of the giant impact, but were then partially replenished by later impacts from the original building blocks of the planets, called planetesimals. This is not a surprise -- planet formation models predict such late impacts -- but their nature, numbers, and most especially size of the accreting bodies are unknown. Presumably, they could have represented the accretion of many small bodies or a few large events. To match observations, the late-arriving planetesimals need to deliver 0.5 percent of the Earth's mass to Earth's mantle, equivalent to one-third of the mass of the Moon, and about 1,200 times less mass to the Moon's mantle.
Using numerical models, the team showed that they could reproduce these amounts if the late accretion population was dominated by massive projectiles. Their results indicate the largest Earth impactor was 1,500-2,000 miles in diameter, roughly the size of Pluto, while those hitting the Moon were only 150-200 miles across. Lead author Bottke says, "These impactors are thought to be large enough to produce the observed enrichments in highly siderophile elements, but not so large that their fragmented cores joined with the planet's core. They probably represent the largest objects to hit those worlds since the giant impact that formed our Moon."
Intriguingly, the predicted distribution of projectile sizes, where most of the mass of the population is found among the largest objects, is consistent with other evidence.
  • New models describing how planetesimals form and evolve suggest the biggest ones efficiently gobble up the smaller ones and run away in terms of size, leaving behind a population of enormous objects largely resistant to collisional erosion.
  • The last surviving planetesimal populations in the inner solar system are the asteroids. In the inner asteroid belt, the asteroids Ceres, Pallas and Vesta, at 600, 300 and 300 miles across, respectively, dwarf the next largest asteroids at 150 miles across. No asteroids with "in-between" sizes are observed in this region.
  • The sizes of the oldest and largest craters on Mars, many of which are thousands of miles across, are consistent with it being bombarded by an inner asteroid belt-like population dominated by large bodies early in its history.
These results make it possible to make some interesting predictions about the evolution of the Earth, Mars and the Moon. For example:
  • The largest projectiles that struck Earth were capable of modifying its spin axis, on average, by approximately 10 degrees.
  • The largest impactor to strike Mars, according to this work and the abundance of highly siderophile elements found in Martian meteorites, was 900-1,100 miles across. This is approximately the projectile size needed to create the proposed Borealis basin that may have produced Mars' global hemispheric dichotomy.
  • For the Moon, the projectiles would have been large enough to have created the South-Pole-Aitkin basin or perhaps a comparable-sized early basin. Moreover, if they contained even a trace amount of volatiles, then the same processes that brought highly siderophile elements to the Moon's mantle may have also delivered its observed abundance of water.