The winter sun feels welcome, but not so the summer sunburn, thanks to proteins on the surface of nerve cells that enable us to sense different temperatures, new research shows.

Scientists have discovered how just a few of these proteins, called ion channels, distinguish perhaps dozens of discrete temperatures from mildly warm to very hot.

Ion channels are pores in cell membranes controlling the flow of charged ions, which turns (nerve cell) neuron signalling on or off -- in this case to inform the body of the temperature the neuron senses, the Journal of Biological Chemistry reported.

Researchers showed that the building blocks, or subunits, of heat-sensitive ion channels can assemble in many different combinations, yielding new types of channels, each capable of detecting a different temperature.

The discovery, in cell cultures, demonstrates for the first time that only four genes, each encoding one subunit type, can generate dozens of different heat-sensitive channels.

"Researchers in the past have assumed that because there are only four genes, there are only four heat-sensitive channels, but now we have shown that there are many more," said Jie Zheng, associate professor of physiology and membrane biology at the University of California Davis School of Medicine, who led the study.

One of the channels they studied, called TRPV1, reacts to hot temperatures -- about 37 degrees Celsius. It is also responsible for the ability to sense spicy foods, such as chili peppers, said a university statement.

A second channel, TRPV3, responds to temperatures of about 26 degrees Celsius. It also senses many food flavours such as those found in rosemary, oregano, vanilla and cinnamon that elicit a warm sensation.

The trick to getting the perfect night's sleep is to be tucked up by 10pm, says new research.

The poll examined the night-time routines of 2,000 adults in Britain who claim to enjoy peaceful slumber and wake on average at 6:47am rested and ready to start the day.

'The actual time people are going to bed is important, with most people ensuring they get a healthy eight or nine hours a night,' says Tania Johnston, spokeswoman for bedlinen brand Bedeck.

According to the poll, the optimum time for your head to hit the pillow is exactly 10pm.This should ideally follow an evening of relaxing activity, with the last meal being eaten an hour and 31 minutes before bed, followed by a cup of tea at 9:10pm.

To encourage the most restful sleep, you should spend 2 hours 7 minutes of down time before bed, including 41 minutes checking emails, 51 minutes surfing the net, 41 minutes of chatting with a partner or family member and 1 hour 45 minutes of television.

Once in bed wearing pyjamas, sleeping on the right hand side and having a partner snuggle into your back is the most common criteria for a good night's sleep.

'It would be great to know that if you followed a certain string of events, and approached bedtime in the same way every night, you would be guaranteed a wonderful night's sleep,' says Ms Johnston.

In a study, researchers have found that treatment with vitamin D reduced the size of uterine fibroids in laboratory rats predisposed to developing the benign tumours.

Uterine fibroids are the most common non-cancerous tumours in women of childbearing age. Fibroids grow within and around the wall of the uterus. Thirty percent of women 25 to 44 years of age report fibroid-related symptoms, such as lower back pain, heavy vaginal bleeding or painful menstrual periods.



Uterine fibroids also are associated with infertility and such pregnancy complications as miscarriage or preterm labour.

Other than surgical removal of the uterus, there are few treatment options for women experiencing severe fibroid-related symptoms and about 200,000 U.S. women undergo the procedure each year.

Fibroids are three to four times more common in African-American women than in white women. Moreover, African-American women are roughly 10 times more likely to be deficient in vitamin D than are white women. In previous research, the study authors found that vitamin D inhibited the growth of human fibroid cells in laboratory cultures.

First author Sunil K. Halder, Ph.D., of Meharry Medical College in Nashville conducted the research with Meharry colleagues Chakradhari Sharan, Ph.D., and Ayman Al-Hendy, M.D., Ph.D., and with Kevin G. Osteen, Ph.D., of Vanderbilt University Medical Center, also in Nashville.

For the current study, the researchers tested the vitamin D treatment on a strain of rats genetically predisposed to developing fibroid tumors. After examining the animals and confirming the presence of fibroids in 12 of them, the researchers divided the rats into two groups of six each: those that would receive vitamin D and those that would not.

In the first group, small pumps implanted under the skin delivered a continuous dose of vitamin D for three weeks. The researchers then examined the animals in both groups. Fibroids increased in size in the untreated rats, but, in the rats receiving vitamin D, the tumors had shrunk dramatically. On average, uterine fibroids in the group receiving vitamin D were 75 percent smaller than those in the untreated group.

The amount of vitamin D the rats received each day was equivalent to a human dose of roughly 1,400 international units. The recommended amount of vitamin D for teens and adults age 70 and under is 600 units daily, although up to 4,000 units is considered safe for children over age 9, adults, and for pregnant and breastfeeding females.

"Additional research is needed to confirm vitamin D as a potential treatment for women with uterine fibroids," said Dr. Al-Hendy.

"But it is also an essential nutrient for the health of muscle, bone and the immune system, and it is important for everyone to receive an adequate amount of the vitamin," the researcher noted.

Louis De Paolo, Ph.D., chief of the Reproductive Sciences Branch of the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development, which funded the study, added "The study results provide a promising new lead in the search for a non-surgical treatment for fibroids that doesn't affect fertility."

Researchers have discovered how marijuana disrupts short-term memory.

The drug impairs users' working memory - the ability to retain and use information over short periods of time. Neuroscientists Giovanni Marsicano of the University of Bordeaux, France, and Xia Zhang of the University of Ottawa Institute of Mental Health Research now show that this common side effect occurs because of a previously unknown signalling mechanism between neurons and non-neuronal cells called astrocytes.
The star-shaped astrocytes have long been considered nothing more than support cells that protect neurons. "Our study provides compelling evidence that astrocytes control neurons and memory," says Zhang. "The supporting actor has become the leading actor."

The psychoactive ingredient of marijuana is tetrahydrocannabinol (THC). Using microelectrodes implanted into the brains of anaesthetized rats, the researchers found that the compound weakens the connections, or synapses, between neurons in the hippocampus, a structure that is crucial for memory formation.

They repeated these experiments in two types of mice that had been genetically modified to alter their production of CB1 receptors, the molecules that interact with THC in the brain. One mouse strain lacked CB1 receptors in hippocampal neurons that synthesize the neurotransmitter glutamate; the other lacked them in those that synthesize the neurotransmitter GABA.
A process of elimination

THC weakened the synapses in both types of mouse in the same way as in unmodified strains, so the researchers reasoned that that the effects of THC must be mediated by CB1 receptors on astrocytes. Marsicano therefore created a third type of mouse, which lacked the receptor in astrocytes. He found that THC had no effect on their hippocampal synapses.

Another set of experiments, on synapse preparations in Petri dishes, revealed that activation of astrocyte CB1 receptors by THC caused receptors for a compound called AMPA to be removed from the membranes of neurons. The removal and insertion of AMPA receptors have been found to mediate weakening and strengthening of synapses respectively, but it was not previously known that astrocytes can control these processes.

Finally, the researchers tested the three strains of mutant mice with a working-memory task in which they had to remember the location of a submerged platform in a water maze. THC impaired the performance of mice lacking the CB1 receptor in neurons that synthesize glutamate and GABA, but not those lacking the receptor in astrocytes.

"It's always difficult to extrapolate from rodents to humans," says Marsicano, "but marijuana impairs working memory in both species, so I expect that similar mechanisms are involved."
Cause and effect

Ben Whalley, a pharmacologist at the University of Reading, UK, says that the work demonstrates an exciting causal link between astrocyte signalling and cognitive function. "It'll be fascinating to investigate their consequences for endogenous cannabinoid signalling in normal brain function and in pathological states," he adds.

Marsicano says that the findings could eventually lead to THC-related drugs that specifically target CB1 receptors expressed by neurons and not astrocytes. Such compounds might have therapeutic effects, for example as painkillers, without affecting the function of working memory.

"But," cautions Whalley, "we still haven't separated out the different effects of neuronal and astrocyte CB1 receptors, so the jury's still out on the potential therapeutic effects of targeting the neuronal receptors."

In the meantime, there may be a far simpler way of minimizing the unwanted side effects of medicinal marijuana.

Scientists, including one of Indian-origin, have combined two new "designer" forms of aspirin into a hybrid substance that appears more effective than either of its forebears in controlling the growth of several forms of cancer in laboratory tests.

Khosrow Kashfi, Ravinder Kodela and Mitali Chattopadhyay point out that NO and H2S are signalling substances produced in the body that relax blood vessels, reduce inflammation and have a variety of other effects.

Scientists previously developed designer aspirin that releases NO in an effort to reduce aspirin's potential adverse effects in causing bleeding in the gastrointestinal tract.

Another designer aspirin that releases H2S was developed which also has anti-inflammatory properties and appears safe to the stomach.
Since NO and H2S are gases with physiological relevance, and Kashfi's group had previously shown beneficial effects with both NO and H2S aspirins, they postulated that a new hybrid that incorporated both of these entities might be even more potent and effective than either one alone.

Their hypothesis has proved to be correct.

They found indications that the new hybrid inhibits the growth of breast, colon, pancreas, lung, prostate and some leukemia cancer cells in laboratory tests.

Some of the NOSH-aspirins tested were more than 100,000 times more powerful against cancer cell growth than aspirin alone. Promisingly, the group reported that their hybrids did not damage normal cells.