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Excessive Calcium Could be Harmful

Excessive intake of calcium supplements may have adverse effect on health, notes a study.
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Postmenopausal and pregnant women, transplant recipients, patients with bulimia (an eating disorder) and individuals on dialysis face the highest risk of developing the calcium-alkali syndrome.

The incidence of the calcium-alkali or the milk-alkali syndrome is growing in large parts, because of widespread use of over-the-counter calcium and vitamin D supplements.

Study authors Stanley Goldfarb and Ami Patel from the University of Pennsylvania School of Medicine (UPSM) recommend changing milk-alkali syndrome’s name to calcium-alkali syndrome because it is now associated with a large calcium intake, not just milk.

The syndrome arose in the early 1900s when patients ingested abundant amounts of milk and (alkaline) antacids to control their ulcers.

This practice increased individual risk of developing dangerously high levels of calcium in the blood, which could cause high blood pressure and even kidney failure.

The incidence of the milk-alkali syndrome declined when newer ulcer medications became available, but it appears to be on the rise again.

Thanks to the increased use of over-the-counter calcium and vitamin D supplements, used mainly as preventive and treatment measures for osteoporosis, many patients with the syndrome now require hospitalisation.

The obvious preventive strategy against the calcium-alkali syndrome is to limit the intake of calcium to no more than 1.2 to 1.5 grams per day, the study co-authors said.

“Calcium supplements taken in the recommended amounts are not only safe but are quite beneficial. Taken to excess is the problem,” said Goldfarb, according to a University of Pennsylvania School of Medicine release.

“Even at the recommended dose, careful monitoring of any medication is wise and yearly determinations of blood calcium levels for those patients taking calcium supplements or vitamin D is a wise approach,” he added.

These findings will appear in the Journal of the American Society Nephrology (JASN).

Source:The Times Of India

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Nod Off to Take Off

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Your brain will function better after a good siesta, say researchers.

If you are a teacher and catch students napping in your class, fret not. The youngsters may not learn what you teach, but will certainly grasp the next lecture very well. This was the conclusion of some sleep researchers, unveiled at a recent meeting of the American Association for the Advancement of Science in San Diego. Napping during the day not only consolidates memory but also improves the brain. The activity is necessary not just for babies; it’s important for adults and old people too, say researchers.

Matthew Walker of the University of California in Berkeley investigated the effect of long afternoon naps on students’ learning ability. His team found that the more you remain awake during the day, the more the brain loses its ability to learn.

At the University of Arizona, professor of psychology Lynn Nadel and his team investigated the effect of napping on babies, and came to the same conclusion — babies learn to abstract better when they nap.

At the University of Pennsylvania School of Medicine, Marcos Frank found something more fundamental — the brain reorganises itself during sleep, and this reorganisation is essential to learning.

Together, neuroscientists are learning new facets of this seemingly passive activity. The brain does not switch off during sleep. In fact, it remains active, in a different way from when you are awake.

“Sleep is a far more complex activity than we thought,” says Walker. What his research shows now is that the brain has a limited short-term memory capacity, and it needs sleep to free up this space frequently by sending some facts to long-term memory. And it can perform this activity only during sleep. This much is now clear, but things get a bit murky after that.

Walker experimented with 40 volunteers, half of whom took a 90-minute nap in the afternoon. When the two teams learned things at noon and at 6pm, the team that did not nap performed much worse the second time.

“We chose a 90-minute nap to provide for a full sleep cycle,” says Walker. This cycle includes stages of rapid eye movement (REM) and non-REM sleep. REM is a dream state of sleep, and was long thought to be the most important phase of sleep. Non-REM sleep is in three stages — 1, 2 and deep sleep. Memory consolidation occurs during stage 2 non-REM sleep, which during the night constitutes 50 per cent of our sleep cycle.

You enter stage 2 non-REM sleep within 15 minutes of falling asleep, and the brain remains in this state for another 40-50 minutes. So for a nap to really enhance learning, it needs to last an hour.

“We do not know yet whether shorter naps are enough,” says Walker. The scientist also hints at another fascinating aspect of sleep — many older people are known to sleep less, and this could be one reason why they have poorer memories. We would know this in the future, when scientists investigate the mechanisms behind sleep and learning.

At the University of Arizona, Nadel and his team tried to investigate the effect of naps on 15-month-old babies. They created an artificial language, with nonsense sounds but having a close relationship structurally — like subject-verb agreement — with English. Like in the Berkeley experiment, babies in this exercise learned before and after naps. Those who napped were able to translate their previous learning to understand what they learned after the naps. In other words, they were able to generalise their knowledge of sentence structure to understand new phrases better.

What they found was slightly different from the Berkeley team’s finding but was equally important. If babies nap within a specific period after learning a new task, they learned to abstract better.

This kind of learning, the ability to detect patterns in a piece of information, is vital to learning many things in later life. Napping is effective only if it happens within four hours of learning. Babies thus need to nap to understand what they learn during the day.

While these are significant findings, Marcos Frank found something fundamental — the young brain grows more connections during sleep. Frank’s earlier research had indicated that the brain was fundamentally different during sleep from during wakefulness.

This difference is in aspects: electrochemical activity, proteins synthesised and biochemical activity. In early development, during the first five years of one’s life, this reorganisation during sleep becomes critical to its capabilities in later life. “We have some evidence that what happens during early years cannot be acquired in later life,” says Frank.

What this means is clear enough. Babies who are deprived of sleep can develop brains that are deficient. While this may not happen for healthy babies, many who suffer from sleep apnea — a disease where you wake up periodically — can have poorly-developed brains by adulthood.

However, while the research shows how important sleep is for our brains, we still do not know everything about this vital daily exercise. It still remains a puzzle, and hopefully the next few years will throw more light on it.

Source: The Telegraph (Kolkata, India)

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A Shot for All

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A vaccine in the making — equally effective for birds, men and other mammals — offers a shield against another outbreak of bird flu.

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Of all the viruses that can cause a devastating pandemic (worldwide outbreak), the influenza virus is the most likely to cause one. Influenza is a tricky disease to control. The world has already seen several outbreaks, of which the influenza pandemic in 1918 was the most serious: at least 20 million people died all over the world then. There were pandemics in 1957, 1968 and 1977, but of much less severity.

Recently, avian influenza (or bird flu) has emerged as a candidate that can cause a serious pandemic. Experts warn that another outbreak is imminent and we have only limited ability to control it if one breaks out. However, several vaccines — now in the laboratory stage — offer hope.

One of the problems of bird flu is that it affects birds as well as humans and other mammals. The virus may be slightly different in each of the animals, and it is difficult to give different vaccines for different animals during a pandemic. At the Department of Veterinary Medicine in the University of Maryland in the US, Daniel Perez and his colleagues have developed a vaccine that can control the disease in birds, humans and rodents. It is based on a region of the virus gene that is common to all the strains. “We have shown that the vaccine works in rodents and does not cause the disease,” says Perez.

This vaccine has been tested in rats but not yet in humans. Meanwhile, at the University of Pittsburgh medical college, scientists are testing a vaccine against the deadliest of all avian flu viruses, the H5N1. This is a genetically engineered vaccine that takes only 10 weeks to manufacture. The other vaccines now in the market are made using chicken eggs, and take several months to manufacture, apart from not being able to provide enough immunity. Two months ago, the institution received a $3.6 million grant to test the vaccine in non-human primates.

Currently, three companies manufacture vaccines against the avian flu virus H5N1, all of them approved in different countries in the last year and a half. Sanofi Pasteur’s vaccine was approved in the US in 2007, GlaxoSmithkline’s vaccine was approved in Europe in May this year. Australia approved a vaccine from CSL Limited. All of them are live attenuated virus — which have been so altered that they can’t cause disease — raised on chicken eggs. While all of them provide some protection, none of them can prevent a pandemic. This is because the virus mutates fast, and we do not know what strain of the virus would be involved in a pandemic.

One of the known — and fortunate — facts about the bird flu virus is its specificity. The virus that infects birds does not easily infect humans. This is why many outbreaks in birds have not resulted in human infections. Which is probably also why human to human transmission has not happened in large numbers so far.

However, such a transmission is not scientifically impossible. Since the virus mutates fast, strains of broader range can emerge. They can infect humans, pigs, rats, birds and other animals. It would be difficult, if not impossible, for us to make different vaccines for different animals. The Maryland University team has shown that it is possible to make a single vaccine effective in many animal species.

This vaccine is based on a DNA backbone that is common to all the strains. This backbone lies inside the virus and not outside. The scientists have a strain of the virus called WF10 with this backbone. They have isolated other influenza viruses that are related to this strain, including the human influenza virus. They had earlier shown that by tweaking the gene of this strain they could make a vaccine effective in birds. Now they have shown that, by further modification, this strain can protect many species against the influenza infection. In particular, they have shown that it provides protection in rats against H5N1, the most lethal strain against which human vaccines are made. Says Perez: “We have done animal trials, but we are yet to do human trials.”

There are other developments that could help in preventing a major pandemic. A series of DNA vaccines against H5N1 are also under development in several institutions. They are the Virology Research Institute in Maryland, which began clinical trials last year, the University of Pennsylvania School of Medicine, and the Rockefeller University. A DNA vaccine is a piece of DNA that can directly make the protein that produces an immune response. It is safe, because it cannot by itself cause the disease. The vaccines can be made rapidly, which is invaluable in case of an epidemic.

However, there are technical issues, which all these teams claim to have solved. If they work, we could soon have a vaccine that can be rapidly made when there is an epidemic. Let us wait and watch their progress.

Sources: The Telegraph (Kolkata, India)