Tag: Ultraviolet

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Health Quaries

How Much Sunshine is needed to Make Enough Vitamin D?

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Vitamin D deficiency is quite common, and a growing list of diseases and conditions are being linked with it. Regular sun exposure, without sunscreen, causes your skin to produce vitamin D naturally. But how much sun do you need?

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You’ve probably seen some vague guidelines, recommending “a few minutes every day.” But these recommendations are far too general to be useful. The amount of sun you need to meet your vitamin D requirements varies hugely, depending on your location, your skin type, the time of year, the time of day, and even the atmospheric conditions.

The Vitamin D/UV Calculator
Scientists at the Norwegian Institute for Air Research have devised a calculator that will take all those factors into consideration and estimate how many minutes of exposure you need for your skin to produce 25 mcg (the equivalent of 1,000 International Units) of vitamin D.

It’s not the most user-friendly interface and it is very easy to enter the wrong information. But once you get past the technicalities, it’s very interesting to see how much the answers change when you vary the input.

It is also not written for US cities so you can go to this page to find out latitude and longitude of many cites and enter the numbers manually. The easiest way may be to simply google “altitude of [your town]”. Remember to convert it to kilometers. One kilometer is about 3300 feet.

If your latitude is 39 S, enter -39. If your longitude is 76 W, enter -76.
You’ll also need to enter the time of day you are going out in the sun, expressed as UTC (Greenwich Mean Time). Here is a converter that will convert local time into UTC. The calculator uses a 24 hour clock, so hours from 1 PM to midnight are expressed as 13 to 24.

The calculator also wants to know the thickness of the ozone layer. I suggest just setting this one to medium.

Be sure to click the radio button next to the entries. They are often not automatically selected when you fill in the values.

Keep in mind that the exposure times given are considered enough to maintain healthy vitamin D status. If you are starting out with a vitamin D deficiency, you might need more.

Resources:

Nutrition Data August 10, 2009

CNN October 4, 2009

Times Online October 10, 2009

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Secrets of a Woman’s Wrinkles With Age

The dream of retaining youthful looks into old age came a step closer yesterday after scientists announced that they had identified the key genes involved in ageing skin. Using data generated by the human genome project – the international effort to decode human DNA – researchers have found 1,500 separate genes that govern how long people stay free from wrinkles.
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The team – led by scientists working for cosmetics giant Procter & Gamble – also believe they have identified the eight major causes of ageing skin.
Despite decades of research and billions of pounds of funding, the cosmetics industry has struggled to develop creams and lotions that reverse ageing.
The best that most of the expensive anti-ageing creams can do is smooth over wrinkles or plump up the skin

Out of the 20,000 to 25,000 known human genes, they have found around 1,500 that play a key role in ageing skin.
‘The human genome project has made it possible for us to analyse ageing right down to the hundreds of genetic changes that happen in our skin as we get older,’ Dr Tiesman said.
Skin ages in eight separate ways, each one controlled by its own group of genes, he added.

Whether you grow old gracefully like Cliff Richard – or wrinkled like Keith Richards – depends partly on your lifestyle and partly on these genes.
Dr Tiesman and his research team believe one of the most important factors is hydration – the way that skin collects and retains its moisture, using molecules that bind water into skin.
As skin gets older, the genes that control this process become less active and skin can retain less moisture, leading to wrinkles.
Dr Tiesman found that up to 700 genes could be involved.
Another ‘ageing pathway’ involves collagen – the protein that gives skin its underlying structure.

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Why skin deteriorates with age: As people get older, the genes that degrade collagen can become overactive, leading to more wrinkles
As people age, the genes that degrade collagen can become overactive, leading to more wrinkles. The team has found 40 genes involved in the collapse of collagen. Inflammation was found to involve about 400 genes, while another group of genes influence how the skin reacts to sunlight.
The skin’s response to ‘free radicals‘ – the molecules that can damage a cell’s damage – is also crucial to how it ages.
By narrowing down the DNA involved with skin ageing, researchers hope to create drugs and creams which can stimulate some genes and suppress others to restore youthful looks.
Professor Anthea Tinker, who studies the social aspect of ageing at King’s College London, said: ‘Older people care about their appearance just as much as any other age group and they are an important and growing market.’
Most anti-ageing creams don’t stand up to scientific scrutiny. However, a reliable clinical trial published earlier this year showed that Boots No7 Protect and Perfect range actually worked.
Manchester University scientists found that a fifth of people who used the cream for six months saw improvement in their skin. The cream appeared to trigger the production of a protein called fibrillin-1, which makes skin more elastic.

Source:http://www.dailymail.co.uk/sciencetech/article-1200689/Secrets-womans-wrinkles-revealed-scientists-discover-genes-linked-eternal-youth.html#ixzz0LqDc4UJ8

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Healthy Tips

Washing Hands Properly Stops Contagious Disease to Spread

Most people know that washing your hands can help to prevent passing on nasty viruses and bacteria. But how many people just flick their hands under a dribbling tap and think that will do? Now hopeless hand washers will be caught with glowing green fingers by a good hand-washing test.
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A new hand-washing training kit uses a cream containing a harmless dye that glows green in ultraviolet light to show up shoddy hand washing. Demonstrators put a blob of cream on people’s hands and send them away to wash them. When they come back, they are often amazed at how much glowing green dye remains on their fingers. If the dye were a microbe, they would be standing a good chance of infecting themselves and passing it on to other people.

The glowing cream can also be used to show how viruses such as those that cause colds and flu can survive on hard surfaces and be spread from hand to hand. Just touching a doorknob that has had a little of the special cream applied to it can make people’s fingers turn green under UV light — and then when they touch another person’s hand the green glow gets passed on.

Sources:
Science Daily June 3, ’09
Society for General Microbiology June3,’09

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News on Health & Science

Jet Lag to be History

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Scripps Research scientists say that they have determined the molecular structure of a plant photolyase protein, which is very similar  to the two proteins that control the circadian clock in humans and other mammals, moving a step closer to making jet lag history.

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The researchers claim that their study has even enabled them to test how structural changes affect the function of such proteins.

“The plant photolyase structure provides a much better model to use to study how the cryptochrome proteins in the human clock function than we have ever had before,” says Dr. Kenichi Hitomi, a postdoctoral research fellow at Scripps Research.

“It’s like knowing for the first time where the engine is in a car. When you know what the most important parts of the protein are, then you can begin to figure out how it functions,” the researchers added.

Dr. Elizabeth Getzoff, professor in the Department of Molecular Biology and member of The Skaggs Institute for Chemical Biology at Scripps Research, says that understanding how these proteins work may be helpful in fixing the clock when needed.

“In addition to decoding how the clock works, a long-term goal is to develop a drug to help people who can’t reset their clock when they need to, like people who work night shifts or travel long distances. Having the three-dimensional protein is a great step forward in both of those pursuits,” she says.

Working in collaboration with researchers from Scripps Research and from other institutions, including two universities in Japan, Hitomi studied Arabidopsis thaliana, a plant native to Europe and Asia that has one of the smallest genomes of all plants.

The researchers point out that just like all other plants, this plant also contains proteins known as photolyases, which use blue light to repair DNA damage induced by ultraviolet light.

They say that humans and mammals possess a homologous protein known as cryptochrome that modulates the circadian clock.

Getzoff says: “This is an amazing, and very puzzling, family of proteins, because they do one thing in plants and quite a different thing in mammals, yet these cousins all have the same structure and need the same cofactor, or chemical compound, to become activated.”

Hitomi adds: “All of these proteins were probably originally responses to sunlight. Sunlight causes DNA damage, so plants need to repair this damage, and they also need to respond to sunlight and seasons for growth and flowering. The human clock is set by exposure to sunlight, but also by when we eat, sleep and exercise.”

Hitomi and his colleagues set about producing proteins from the Arabidopsis thaliana genes that produce two related photolyase enzymes. These genes had been cloned earlier in the laboratory of co-author Dr Takeshi Todo of Kyoto University.

The researchers moved the gene from the plant into E coli bacteria to produce a lot of the protein, and later crystallized it to determine the atomic structure by using X-ray diffraction.

The researchers then produced a variety of mutant proteins in order to test the functional structure of the enzymes.

“We can now look at things that are the same and different between human and mouse cryptochromes and plant photolyases. Our results provide a detailed, comparative framework for biological investigations of both of these proteins and their functions,” says Hitomi.

He believes that his team’s findings may form the basis of drugs that can ease jet lag and regulate drug metabolism, as well as help better understand some fascinating circadian clock disorders that have been found in mice and man.

The study has been published in The Proceedings of the National Academy of Sciences.

Sources:The Times Of India

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Caffeine in Sunscreen May Cut Skin Cancer Risk

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Adding caffeine to sunscreens could boost protection against the most common form of skin cancer, claim scientists.

According to the study, conducted by a team from Harvard Medical School and Pfizer, caffeine has an effect on cells which can go on to cause non-melanoma skin cancers and found that the stimulant encourages the harmful cells to die.

The breakthrough study shows at caffeine helps eliminate human cells damaged by UV light, which can develop into cancer, by causing them to commit suicide, reports The Telegraph.

Writing in the Journal of Investigative Dermatology the authors said: “These data suggest topical application of caffeine…perhaps in a sunscreen or after-sun preparation could be investigated as an approach to minimise or reverse the effects of UV damage in human skin.”

Gavin Greenoak, Managing and Scientific Director of the Australian Photobiology Testing Facility (APTF) at the University of Sydney, Australia, said: “This research show the potential to improve protection from non-melanoma skin cancer by adding caffeine to topical sunscreens or through more specific drug synthesis.”

Sources: The Times Of India

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