Sunday, August 23, 2009

Another big medical backflip: "Stop prescribing Tamiflu for routine swine flu cases"

Healthy people who catch swine flu should not be given antiviral drugs, as most will recover within a week, the World Health Organisation has said. The drugs are offered to anyone in England with flu-like symptoms but guidance from the UN health agency suggests that the side-effects of taking medication may outweigh the benefits for otherwise healthy people.

Tamiflu or Relenza should, however, still be used as soon as possible on people with severe illness or whose condition is deteriorating, the WHO advises. Those in at-risk groups — such as pregnant women or people with an underlying medical condition such as diabetes — should also receive treatment promptly.

The Department of Health, which has stockpiled enough antivirals to treat up to 80 per cent of the population, said that it would maintain a “safety-first” policy of offering everyone the medication.

Overall illness and the number of people in hospital with swine flu have declined in the past fortnight. However, the number of deaths linked to the H1N1 virus in Britain increased after the deaths of women in Wales and Northern Ireland. The woman patient in Northern Ireland, the first victim in the Province, was said to have had an underlying health condition. She died on Thursday night in hospital. Her family has asked for her identity to be kept private.

A 55-year-old woman from Caerphilly County Borough was the first fatal case in Wales. She died in hospital last Saturday after developing circulatory complications. She was admitted to the Royal Gwent Hospital, Newport, on August 2 after falling ill with flu-like symptoms. She tested positive for swine flu and was put on a course of antiviral medicine. Four days later she was transferred to the intensive care unit of the University Hospital of Wales, in Cardiff, with heart-related problems. No further details were released at the family’s request.

The latest WHO advice, from a panel of international experts, came as new figures showed that 45,986 courses of antivirals were given to patients in England last week. In the previous week 90,363 had been given out after callers contacted the National Pandemic Flu Service, the telephone and internet service that allows patients to obtain medication without seeing a doctor.

There have been fears that the mass use of Tamiflu would encourage the H1N1 swine flu strain to become resistant to the antiviral. Researchers have also expressed concern over the side-effects of the drug, including sickness, nightmares and insomnia in children.

A team from the University of Oxford said earlier this month that children with mild symptoms should not be given the antiviral, and urged the Department of Health to urgently reconsider its policy.

The new advice on the WHO website said that most patients were experiencing typical flu symptoms and would get better within a week. Its experts recommended prompt antiviral treatment for all children aged under 5 with severe or deteriorating illness but added that older children, who were otherwise healthy, “need not be given antiviral treatment unless their illness persists or worsens”.

Illness due to swine flu appears to have peaked for the summer, official figures showed, with an estimated 11,000 cases being diagnosed last week, down on 25,000 the previous week.

Only one person in ten in England who sought treatment from the Pandemic Flu Service or their doctor last week actually had the virus, the Health Protection Agency said yesterday. Sir Liam Donaldson, the Chief Medical Officer, warned that a second wave of illness was expected as Britain entered the winter flu season but said that it was virtually impossible to predict accurately when this would peak.


Why sleep? Scientist delves into one of science's great mysteries

Bats, birds, box turtles, humans and many other animals share at least one thing in common: They sleep. Humans, in fact, spend roughly one-third of their lives asleep, but sleep researchers still don't know why. An evolutionary explanation is offered below

According to the journal Science, the function of sleep is one of the 125 greatest unsolved mysteries in science. Theories range from brain "maintenance" — including memory consolidation and pruning — to reversing damage from oxidative stress suffered while awake, to promoting longevity. None of these theories are well established, and many are mutually exclusive.

Now, a new analysis by Jerome Siegel, UCLA professor of psychiatry and director of the Center for Sleep Research at the Semel Institute for Neuroscience and Human Behavior at UCLA and the Sepulveda Veterans Affairs Medical Center, has concluded that sleep's primary function is to increase animals' efficiency and minimize their risk by regulating the duration and timing of their behavior. The research appears in the current online edition of the journal Nature Reviews Neuroscience.

"Sleep has normally been viewed as something negative for survival because sleeping animals may be vulnerable to predation and they can't perform the behaviors that ensure survival," Siegel said. These behaviors include eating, procreating, caring for family members, monitoring the environment for danger and scouting for prey. "So it's been thought that sleep must serve some as-yet unidentified physiological or neural function that can't be accomplished when animals are awake," he said.

Siegel's lab conducted a new survey of the sleep times of a broad range of animals, examining everything from the platypus and the walrus to the echidna, a small, burrowing, egg-laying mammal covered in spines. The researchers concluded that sleep itself is highly adaptive, much like the inactive states seen in a wide range of species, starting with plants and simple micro-organisms; these species have dormant states — as opposed to sleep — even though in many cases they do not have nervous systems. That challenges the idea that sleep is for the brain, said Siegel. "We see sleep as lying on a continuum that ranges from these dormant states like torpor and hibernation, on to periods of continuous activity without any sleep, such as during migration, where birds can fly for days on end without stopping," he said.

Hibernation is one example of an activity that regulates behavior for survival. A small animal, Siegel noted, can't migrate to a warmer climate in winter. So it hibernates, effectively cutting its energy consumption and thus its need for food, remaining secure from predators by burrowing underground.

Sleep duration, then, is determined in each species by the time requirements of eating, the cost-benefit relations between activity and risk, migration needs, care of young, and other factors. However, unlike hibernation and torpor, Siegel said, sleep is rapidly reversible — that is, animals can wake up quickly, a unique mammalian adaptation that allows for a relatively quick response to sensory signals.

Humans fit into this analysis as well. What is most remarkable about sleep, according to Siegel, is not the unresponsiveness or vulnerability it creates but rather that ability to reduce body and brain metabolism while still allowing that high level of responsiveness to the environment. "The often cited example is that of a parent arousing at a baby's whimper but sleeping through a thunderstorm," he said. "That dramatizes the ability of the sleeping human brain to continuously process sensory signals and trigger complete awakening to significant stimuli within a few hundred milliseconds."

In humans, the brain constitutes, on average, just 2 percent of total body weight but consumes 20 percent of the energy used during quiet waking, so these savings have considerable adaptive significance. Besides conserving energy, sleep invokes survival benefits for humans too — "for example," said Siegel, "a reduced risk of injury, reduced resource consumption and, from an evolutionary standpoint, reduced risk of detection by predators."

"This Darwinian perspective can explain age-related changes in human sleep patterns as well," he said. "We sleep more deeply when we are young, because we have a high metabolic rate that is greatly reduced during sleep, but also because there are people to protect us. Our sleep patterns change when we are older, though, because that metabolic rate reduces and we are now the ones doing the alerting and protecting from dangers."


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