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Grow Your Own Teeth

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Scientists have made teeth from stem cells in a world first that could make dentures a thing of the past.

They looked like normal teeth, were sensitive to pain and chewed food easily.
While the experiments were on mice, they pave the way for people to ‘grow their own teeth’ as required.

The new tooth at full size, seen at the back of the mouse’s mouth.
The technique could also be adapted to other organs, allowing hearts, lungs and kidneys to be grown inside the body to replace parts worn by age or damaged by disease.
The Japanese study focused on stem cells – ‘master cells’ with the ability to turn into other cell types.

The researchers from the Tokyo University of Science identified two types of stem cell, which together contain all the instructions for a fully grown tooth.
The cells were grown in the laboratory for five days until they formed a tiny tooth ‘bud’.
This was then transplanted deep into the jawbone of a mouse that had had a tooth removed.
Five weeks later, the tip of the tooth broke through the gum. And after seven weeks, it was fully-grown, the journal Proceedings of the National Academy of Sciences reports.
The researchers, who repeated the experiment many times, also showed that the new, bioengineered teeth were fully-functional.

Dr Kazuhisa Nakao said: ‘Every bio- engineered tooth erupted through the gum and had every tooth component such as dentine, enamel, pulp, blood vessels, nerve fibres, crown and root.’
Importantly, the rodent recipients had no trouble eating.
The cells used were take from mouse embryos, but the researchers believe it should be possible to make teeth from other types of cell as well.
They are now looking for suitable cells in people. Possibilities include skin cells and cells from the pulp inside teeth.

They also have to work out how to control the size of the bio-engineered teeth, as those grown in the experiments were slightly smaller than usual.
The process would also have to be speeded up if it was to be used on people as human teeth take years to form.


However, the pioneering technology could one day allow those with teeth missing to fill the gaps in their smile without having to resort to false teeth, bridges or synthetic implants.
Experts believe that using ‘living’ teeth rather than artificial ones would be better for oral health and may also provide a more natural ‘bite’. Bio- engineered teeth are likely to cost around £2,000 each – a similar price to the implants used at the moment.
But Britain’s 11 million denture wearers should not throw away their fixative creams and gels quite yet.

The technology is still at a very early stage and the Japanese researchers believe it will not be widely used by dentists for at least 15 years. Despite this, British experts said it was an important landmark.

Professor Robin Lovell-Badge, a stem cell researcher at the National Institute for Medical Research in London, said the work was ‘excellent’ and highlighted the promise of using bio-engineering to make complex structures.

But he cautioned that the researchers had yet to find cells suitable for use in people.
Professor Damien Walmsley, of the British Dental Association, said: ‘If you lose a tooth at the moment, one of the options is a metal implant. If you could have a natural replacement, that would be good.’

Natural-looking replacements-also have massive psychologicalbenefits for self-conscious patients.
The technique of creating cell ‘buds’ could be applied more widely to grow other organs, such as hearts, kidneys and livers, inside the body.
Lead researcher Professor Takashi Tsuji said: ‘The ultimate goal of regenerative therapy is to develop fully-functioning bioengineered organs that can replace lost or damaged organs following disease, injury or ageing.
‘Our study makes a substantial contribution to the development of bio- engineering technology for future organ replacement therapy.’

Source:Mailonline. Dated: Aug.4.2009.

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The Smell Secrets

Smells can be mapped and the relative distance between various odors determined:

……...CLICK & SEE

Odors waft up the nasal cavity to a patch of nerve cells above the eyes. From there, scent signals go to the olfactory bulb, higher brain areas involved in discrimination (frontal lobe), and primitive areas linked to emotions (limbic system).

Nearly 25 years ago, US physician and writer Lewis Thomas famously said of the sense of smell: “It may not seem a profound enough problem to dominate all the life sciences, but it contains, piece by piece, all the mysteries.” In humans, the olfactory sense can elicit vivid memories as much as it can evoke the imagination. But for most animals, smell is the primal sense that enables them to find food, detect predators and locate mates. From fruit flies to humans, one question has long puzzled researchers: how does the brain know what the nose is smelling?

A few years ago, US researcher Richard Axel and his student Lind Buck resolved this puzzle and won the 2004 Nobel Prize. In less than four years since, a team of Israeli scientists has shown that smells can be mapped and the relative distance between various odours determined.

The work which lays down the basic laws underlying our sense of smell has appeared in a recent issue of the journal Nature Methods. “This looks like an interesting attempt to classify odourants in relation to function. There is a need for being able to make such predictions with respect to odourants,” says Gaiti Hasan, a scientist at the National Centre for Biological Sciences, Bangalore, who works on the science of smell.

Unlike in smell, the physical attributes of vision and sound can be measured. For instance, one can easily know whether a particular musical note is different from another, because the ear can comprehend the difference in their frequencies. But no such physical relationship has been discovered for smells, partly because odour molecules are much more difficult to pin down than sound frequencies.

In order to create the map, researchers from the Weizmann Institute of Science, led by neurobiologist Noam Sobel, began working with 250 odourants. For each of these odourants, the scientists generated a list of around 1,600 chemical characteristics. Plotting these characteristics, they created a multi-dimensional map of smells that revealed the distance between one odour molecule and another.

Persistent research over the years, however, has helped the Israeli scientists tighten the list of traits needed to locate an odour on the map down to around 40. Subsequently, they checked to see whether the brain recognised this map as it recognises musical scales. Working with fruit flies to rats to honey bees, they studied the neural response patterns to smells and found that in all these species the closer any two smells were on the map, the more similar were the neural patterns.

Subsequently, the scientists tested 70 new smells by predicting the neural patterns that they would arouse. They later matched their predictions with experiments carried out at the University of Tokyo and found that their predictions closely matched the results of the experiments.

These findings lent support to the theory that, contrary to the commonly held view that smell is a subjective experience, there are universal laws governing the organisation of smells. These laws determine how our brain perceives them, says Sobel.

If the parameters they use to classify the odours are relatively simple, this is a significant achievement, Hasan told KnowHow. Hasan thinks such a map will help predict what the brain’s response to an unknown odourant would be.

In the past, scientists had tried to develop a method to measure smell. The method was rather crude and was based on the number of carbon atoms present in a particular compound. It failed miserably as scientists found that two compounds that have a similar chemical structure and differ by just one carbon atom elicited very different responses in the olfactory sensory neurons, the workhorse of the nose in detecting smells.

The smell map may be of potential interest to industry. For instance, characterising a smell on the basis of how the brain recognises it can enable it to be digitised and transferred via the computer in future. This could, for example, help the perfume industry develop superior perfumes.

You may click to see:->Secrets of smell land Nobel Prize

> Researchers Sniff Out Secrets of Smell

Sources: The Telegraph (Kolkata, India)

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Breaking Up Workouts Burn Fats Faster

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 Breaking up an exercise session, by adding a rest period in between, may boost a workout’s fat-burning efficiency, a team of Japanese and Danish researchers reports.

click & see the pictures

When men exercised for two 30-minute stretches, taking a 20-minute rest break in between, they burned more fat than when they exercised for a single 60-minute session, and then rested afterward, Dr. Kazushige Goto of the University of Tokyo and colleagues found.

Current recommendations on exercise for preventing or treating obesity emphasise longer exercise sessions, Goto and his team note in the Journal of Applied Physiology . But there is evidence that following one exercise session with another workout may increase fat metabolism, they add.

To investigate, the researchers had seven healthy men complete one long workout and then two shorter workouts on exercise bicycles, measuring several different indicators of fat metabolism. All exercised at 60 percent of their maximum level of exertion.

When the men performed the two shorter exercise sessions, their blood levels of free fatty acids and other substances rose during the rest period, indicating greater fat metabolism. Levels of these substances also were higher during an hour-long rest period after the two-part exercise session.

Greater fat metabolism was recorded during each of the rest periods in the two-part session than during the rest period following the single, longer workout.

The men also showed lower levels of insulin and blood glucose during the second phase of the two-part exercise session.

While the proportion of total calories burned did not differ between the two workouts, fat represented nearly 77 percent of the calories burned in the recovery period after the two-part exercise session, compared with about 56 percent of calories burned in the recovery period after the single long exercise session.

Although a single bout of prolonged exercise is often performed in response to a physician’s advice to exercise more, exercising for the same amount of time but with rest periods in between may be more effective, especially for sedentary or overweight individuals, the researchers conclude.

Source: The Times Of India

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Why desire drives us wild

A new brain study has pointed out why most mammals experience moments of overwhelming desire – be it for food, sex or other things – that can be followed by seemingly magical feelings of satisfaction. But the find suggests we are often likely to be left wanting rather than satisfied.

According to a study recently published in the Journal of Neuroscience, wanting and liking are separate urges in the brain that are controlled by different circuits.

When these urges occur in sync, the impact on the brain is very powerful.

But there’s a catch. Mammal brains appear to have fewer mechanisms for pleasure than they do for desire.

“Our results suggest we all are inherently susceptible to wanting more than we’ll actually enjoy, at least in certain situations,”co-author Kent Berridge told Discovery News.

Berridge, a University of Michigan psychology researcher, added, “If separable brain circuits exist for liking and wanting, then a person who had selective activation of the wanting circuit would want more without liking more.”

Such want/like dissociations can lead to addictions with drugs, sex, food, gambling and more, the researchers believe. Some people also appear to be prone to experiencing the out-of-sync phases.

For the study, Berridge and colleague Kyle Smith used a painless microinjection technique to deliver droplets of an opioid drug into a pleasure hotspot within the brains of rats.

The drug caused the rats to want to eat three times their normal amount of food – in this case, sugar – while liking it twice as much as usual.

The scientists measured the “like” degree in rats by studying their facial expressions and behaviours while they ate. These included lip and paw licking.

The researchers then turned off a rat pleasure circuit by microinjecting an opioid suppressant into another part of the rodent’s brain. The rats reacted by still wanting sugar, but exhibited no extra signs of liking it.

Finally, the scientists used a technique called Fos mapping, which shows activated portions of the brain based on colour changes due to proteins that affect certain neural circuits.

This, and the other experiments, revealed the separate want and like “hedonic hotspots”in two areas deep within the brain. Rats, humans and other mammals share these same regions and related circuitry, so rat desire can be comparable to human desire.

Source:The Times Of India