sábado, 15 de fevereiro de 2014
Intravenous Vitamin C May Boost Chemo's Cancer-Fighting Power
WEDNESDAY Feb. 5, 2014, 2014 -- Large doses of intravenous vitamin C have the potential to boost chemotherapy's ability to kill cancer cells, according to new laboratory research involving human cells and mice.
Vitamin C delivered directly to human and mouse ovarian cancer cells helped kill off those cells while leaving normal cells unharmed, University of Kansas researchers report.
"In cell tissue and animal models of cancer, we saw when you add IV vitamin C it seems to augment the killing effect of chemotherapy drugs on cancer cells," said study co-author Dr. Jeanne Drisko, director of integrative medicine at the University of Kansas Medical Center.
In follow-up human trials, a handful of cervical cancer patients given intravenous vitamin C along with their chemotherapy reported fewer toxic side effects from their cancer treatment, according to the study published in the Feb. 5 issue of Science Translational Medicine.
"In those patients, we didn't see any ill effects and we noticed they had fewer effects from the chemotherapy," Drisko said. "It seemed to be protecting the healthy cells while killing the cancer cells."
Intravenous vitamin C has been considered an integrative medical therapy for cancer since the 1970s, Drisko noted.
But vitamin C's cancer-killing potential hasn't been taken seriously by mainstream medicine ever since clinical trials performed by the Mayo Clinic with oral vitamin C in the late 1970s and early 1980s found no anti-cancer effects, she explained.
Researchers have since argued that those trials were flawed because vitamin C taken orally is absorbed by the gut and excreted by the kidneys before its levels can build up in the bloodstream.
But it's been hard to attract funding for further research. There's no reason for pharmaceutical companies to fund vitamin C research, and federal officials have been uninterested in plowing research dollars into the effort since the Mayo research was published, Drisko said.
This latest investigation began with researchers exposing human ovarian cancer cells to vitamin C in the lab. They found that the cells suffered DNA damage and died off, while normal cells were left unharmed.
The researchers then tested vitamin C on mice with induced ovarian cancer. The vitamin appeared to help chemotherapy drugs either inhibit the growth of tumors or help shrink them.
Finally, the team conducted a pilot phase clinical trial involving 27 patients with stage III or stage IV ovarian cancer.
The patients who received intravenous vitamin C along with their chemotherapy reported less toxicity of the brain, bone marrow and major organs, the investigators found.
These patients also appeared to add nearly 8.75 months to the time before their disease relapsed and progressed, compared with people who only received chemotherapy. The researchers did note that the study was not designed to test the statistical significance of that finding.
Vitamin C in the bloodstream helps kill cancer cells because it chemically converts into hydrogen peroxide when it interacts with tumors, Drisko said.
"If you can get your blood levels of vitamin C very high, it gets driven into the space around the cancer cells," she explained. "In that space, it's converted into hydrogen peroxide. It's very similar to what our white blood cells do. They create hydrogen peroxide to fight infection."
Dr. Stephanie Bernik, chief of surgical oncology at Lenox Hill Hospital in New York City, said intravenous vitamin C therapy is not unheard of among cancer doctors.
"I've had patients come in and say they were doing vitamin C intravenous therapy," Bernik said. "I always tell them we don't know enough to know whether it is good or bad."
This new research raises interesting possibilities, but until larger clinical trials are conducted Bernik says her advice to patients will not change.
"You have to do a bigger study with patients and look at outcomes. You also have to make sure these treatments don't interfere with the treatments we're giving currently," she said. "There may be some efficacy in what they're doing. It just needs to be proven. This is just the start of more studies looking at this in-depth."
Dr. Michael Seiden, chief medical officer for The US Oncology Network, agreed.
"It is important to emphasize that many vitamin therapies have shown interesting results when applied to cancer cells in test tubes yet, to date, these approaches typically are not effective and occasionally prove harmful in human studies," he said. "At this time, there is still no evidence that high-dose vitamin C should be part of the treatment for women with ovarian cancer."
While she agreed that larger trials need to be conducted, Drisko was not as hesitant.
"It's safe. It's inexpensive. There's a plausible mechanism we're investigating for why it works," she said. "We should be using this in patients, rather than dragging our feet and worrying about using it at all."
More information
Visit the U.S. National Cancer Institute for more on vitamin C and cancer.
Posted: February 2014
World Cup 2014 Brazil: a guide for visitors
Playing soccer on Ipanema beach. Photo: Reuters
The Socceroos may not be fancied for the 2014 World Cup but for travellers to Brazil, everyone is a winner, writes football fan Michael Visontay.
What do you get when you stage the world's most popular event in the world's sexiest country? A football fest in a G-string.
The World Cup in Brazil starts in June and looms as a month of goals and groans to a backdrop of shimmering beaches and shimmying bodies, Amazon forests, amazing architecture, waterfalls and wildlife.
Sunrise over Rio. Photo: Flavio Veloso
It's easy to see why Australians have made a beeline to follow the Socceroos. In last year's main ticket ballot, the most applications came from Brazil, followed by the United States, Australia, England and Argentina. Think about it: Australia, with 23 million people, applied more than England, the home of football with 53 million, or football-mad Argentina, with 41 million people, who can drive across the border if they want to
The results of the main ticket ballot will be known by March 11 but there's no point waiting till then to prepare for a daunting logistical challenge: getting there, finding somewhere to stay, getting around and trying to enjoy the experience amid all the tourist traps, traffic jams and potential political protests.
With World Cups, the laws of economics are simple: the more inaccessible the country, the more outrageous the prices charged by airlines, hotels and tour operators.
The old town of Salvador de Bahia. Photo: Alamy
Brazil is a prime example. If you haven't bought your flights yet, pour a stiff drink before you read on.
GETTING THERE
There are basically four ways to fly to Brazil: via Santiago in Chile, Dubai, Johannesburg or Los Angeles.
Sao Paulo is the main hub in Brazil and flying to Rio de Janiero will generally cost more than flying to Sao Paulo or Brasilia, the capital. You need to think about trading the cost of an extra flight versus convenience.
Whether you stay two weeks or four, flights on all of the above routes may cost more than $3000, most closer to $4000.
The quickest way to Brazil is with LAN Airlines/Qantas via Santiago, Chile, and on to Rio (27 hours). If you have plenty of time and want a stopover, the cheaper route is via LA and then (via Miami) to Sao Paulo or Brasilia: this can cost $3200 if you stop at Hawaii as well as Miami, or $3600 if you fly direct from Sydney to LA.
Historic Paraty village. Photo: Corbis
If you want to fly to Rio, Emirates has a fare for $3900 via Dubai (30 or so hours total). My son and I have decided to fly on Qantas via Johannesburg (14 hours), stop over for a night and then fly to Sao Paulo on South African Airways (nine hours).
This costs almost $4000 a person but has one hidden advantage. You can redeem Qantas frequent flyer points as Classic points on the Jo'burg leg, something you can't do if you fly via Santiago.
GETTING AROUND
Football frenzy in Maracana Stadium. Photo: Reuters
Brazil is massive, 10 per cent larger than Australia in area, so moving from one part to another requires planning to enjoy the experience beyond merely getting to matches.
This will be hard enough in itself, as every team plays their first-round games in different cities, most of them a long way from each other.
Australia plays in Cuiaba (1500 kilometres west of Sao Paulo), Porto Alegre (1200 kilometres south) and Curitiba (a mere 340 kilometres from Sao Paulo) - which brings us to planes, trains and automobiles.
Street football. Photo: Ricardo Funari
Firstly, scratch trains - Brazil's military dictatorships of the 1970s ran them into the ground. If you don't want to drive, the main options are flights or buses.
The former are quick but filling up fast. Inter-city budget flights booked a few months ago sold out and prices are rising every week.
The domestic airlines in Brazil are Tam, Gol and Avianca.
Street food in Salvador de Bahia. Photo: Alamy
Having checked the fares nearly every day since getting our tickets in the earlier December ballot, I have not yet seen evidence of extra flights being put on.
If you're unlucky, you might pay several hundred dollars for a one-hour round trip. For example, Cuiaba is half-way to the Amazon and flights there are already quite expensive. Getting out is another challenge altogether. Porto Alegre is easier because it's serviced by Rio flights as well as Sao Paulo.
And although Curitiba is drivable from Sao Paulo, it is hardly worth the effort to rent a car and drive, even if you have four people in your group, like we do.
Between the three-hour plus trip, and getting out of a city of 18 million people, you're spending more than half a day on the road before you even get to your destination city, let alone park and queue with 40,000 fans.
Buses are an obvious compromise: the national network is extensive, regular and affordable, though slow (six hours for 420 kilometres from Rio to Sao Paulo). You don't have to worry about parking or being held-up. But how much time do you want to spend on the road?
WHERE TO STAY
There are two basic ways to organise your accommodation, and they will determine how you travel around the country to matches, and seeing the sights.
Either choose one city as a base, or fashion a flying "road trip" through the cities where your matches are played.
We chose the first option: a base in Rio. If you're staying for longer than two weeks, it makes the most sense.
You can find an apartment, generally cheaper than hotels and with more room, take in the colour of the Fanfest at Copacabana Beach and relax between match-day flights.
The city's modern, high-rise blocks routinely have 24-hour security. But you should ask, not assume.
On the other hand, staying in Rio or Sao Paulo means doubling up on a few more flights than if you simply fly from one match city to another, staying a few days in each.
This second option is worthwhile if you only plan to go for two weeks to follow Australia's first-round matches.
It also allows you to stay in more modestly sized cities, with populations of 1-2 million and fewer traffic issues.
But it does mean you're forever in hotels and forced to take all your luggage with you. We found a genuine two-bedroom apartment near the Botanical Gardens in Rio, about 30 minutes from the beaches.
There are countless apartments around Copacabana, Ipanema and the upmarket suburb of Leblon just behind them. However, you need to check very closely exactly what is offered. Many claim to be suitable for four people, but have only one bedroom and a sofa bed in a cramped lounge area.
If you're looking for hotels outside the two big centres, you need to move quickly to get something decent and close to the centre of town on match days. Perhaps owing to its remoteness, or its warm winter climate, Cuiaba has virtually no hotel rooms available around Australia's match. And I mean nada - except for a dorm bed for a few hundred dollars a night.
My hotel booking site had a few in the satellite cities 50-100 kilometres away, but that was it.
We have an early flight out after the Australian match and are already resigned to spending the night in the airport. It's that bad.
Other cities have more options but there is huge demand for three-star accommodation in city centres. Beyond that, you're looking at $400-$500 a night for a twin/double room.
BEYOND FOOTBALL
Despite these logistics to think about, make sure you leave enough time to sample the sights and delights beyond football.
Brazil boasts beaches and wildlife, man-made and natural beauty to rival the northern hemisphere capitals. Plus the X-factor: samba culture, thumping nightlife and the siren call of The Girl From Ipanema.
To fit in sightseeing between matches, half-way along the coast between Rio and Sao Paulo lies a beautiful colonial village called Paraty, recommended by several friends.
An hour north of Sao Paulo is Brasilia, a city built from scratch in 1956 to replace Rio as the national capital. Designed by the modernist architect Oscar Niemeyer, Brasilia has divided opinions since it was founded in 1960. Its layout and buildings set it apart from the rest of the country, although the critic Robert Hughes described it as "a ceremonial slum".
For beach culture, further north still lies the colonial splendour of Salvador, with a strong African flavour, and the beautiful beaches of Recife, Natal and Fortaleza. In the south, Porto Alegre offers a decided Argentine influence and a smattering of German and Polish culture. Further south again lie the extraordinary Iguazu Falls on the Argentine border (you should try to see the falls from both sides of the border).
Way out to the west lies the almost mythical city of Manaus, deep in the Amazon, with a dazzling array of wildlife and nature options. And this grab-bag does not even begin to scratch the surface.
GETTING MATCH TICKETS
So, you have tickets to some or all of the three Australian matches but you want more.
Depending on your luck in the draw, and your bank balance, there are several ways to get extra tickets: buy them in the official FIFA ballots; go to ticket shops which inflate the prices by anything up to 300 per cent, or swap and trade your tickets on fan sites such as Ticket4football (English phone number, Spanish address) or Big Soccer (American).
I have used Big Soccer, especially in Germany 2006 when demand was intense, as it is now. The fans I met and swapped with proved to be reliable and courteous and I had no nasty surprises. I am using Big Soccer again this year and have found willing and reliable trading partners.
SECURITY
Last June, Brazil was ignited by a series of grassroots political protests against the cost of staging the World Cup and how the money could have been better spent on much-need public infrastructure. The organisers have vowed to mount more protests as the global spotlight shines on their country.
Add to that the endemic police-gang tensions in the two major cities and Brazil's reputation as a country where everyone gets robbed, and you could be excused for thinking it's all too hard.
But they said that for South Africa too. In truth, there is never a safer time to visit an edgy country than during the World Cup or Olympics.
Governments put on huge extra police and security measures and a national pride ripples through the local population, bringing out their best behaviour.
Nevertheless, there are obvious precautions: don't wear an expensive watch or wave around your smartphone or digital camera in public.
Take a photo of your passport and leave it on your smartphone; that way you don't have to carry it around with you.
Carry a spare credit card in a safe place, and consider reducing the limit on your everyday card to something low enough for buying the odd meal or trinket, but nothing more.
In any case, you have probably paid for nearly all of your major costs before leaving Australia.
If that's all too scary, imagine this: a giant samba party at Ipanema, free cocktails all round and a giant TV screen behind the dancers showing a match where Australia thrashes Spain.
For more information, begin with fifa.com ; flightcentre.com.au and visitbrasil.com .
NASA's Cold Atom Lab to make the ISS the coldest spot in the Universe
Artist's conception of a quantum atomic gas undergoing laser cooling in an ultracold refrigerator (Photo: NASA)
Quantum physics likes the cold. In particular, macroscopic quantum phenomena such as superconductivity, superfluidity, and Bose-Einstein condensates (BECs) are only found at quite low temperatures. While current refrigeration methods can attain temperatures of a few nK (nanoKelvin), attaining still lower temperatures is largely prevented by the need to support the cooling matter against the pull of Earth's gravity. Now NASA's Cold Atom Lab, scheduled for installation on the ISS in 2016, will aim for temperatures roughly three orders of magnitude smaller.
Shedding light on the nature of quantum matter (forms of matter in which some macroscopic properties are dominated by quantum mechanics) has been a major theme of the past half-century in physics, having collected nine Nobel Prizes shared among 23 Laureates in that period. Examples include superconductivity, superfluidity, the fractional quantum Hall effect , and Bose-Einstein condensates .
Presumably new and unexpected quantum effects remain to be discovered at colder temperatures. In particular, experiments with a quieter background are more likely to provide data which can reveal tiny effects normally overshadowed by thermal noise. The potential exists to obtain clues to the nature of space and time, quantum entanglement, the Equivalence Principle, and other issues with which we still struggle.
A range of novel applications are also within reach, such as quantum sensors based on atomic matter-wave interferometry, in which the wave nature of atoms is so enhanced owing to the low experimental temperatures that they can be split and made to interfere with themselves.
How can extreme cold be understood? In the Kelvin temperature scale, zero temperature is absolute zero, the point at which all classical motion stops. The temperature change associated with one degree Kelvin is equal to that of one degree Centigrade.
There are markers on the path to ultracold temperatures. Dry ice has a temperature of 195 K, liquid nitrogen boils at 77 K, and helium becomes liquid at 4.2 K. The cosmic microwave background of the Universe corresponds to 2.725 K, and the coldest known natural place in the Universe, the Boomerang nebula, is a chilly 1 K.
The markers are nice, but matter at a temperature of 1 pK (picoKelvin) is a trillion times colder than the Boomerang nebula; a huge leap over which to get a feel for truly extreme cold. One approach is to look at the de Broglie wavelength (roughly the quantum size) of an atom in a cold gas.
At room temperature a mid-weight atom has a wavelength of about 0.02 nm, which is about 10 times smaller than the physical size of the atom. The discrepancy in sizes explains why atomic gases show essentially no quantum nature at room temperature. At 1 K, the wavelength is about 0.3 nm, a bit larger than the separation of atoms in a liquid, and indeed one sees quantum mechanical superfluid helium appearing at roughly this temperature.
At a picoKelvin, however, the wavelength is roughly 0.3 mm, about the size of a medium grain of sand, and vastly larger than the classical size of the atoms. When the quantum waves of the individual atoms in a gas overlap, the system becomes dominated by quantum effects; in the case of an atomic gas made of bosons, you get a Bose-Einstein condensate.
The quantum correlations from which properties of ultracold matter emerge are usually rather weak, and easily disrupted by thermal fluctuations, thereby preventing a condensed quantum phase from forming. As a result, quantum properties usually appear at lower temperatures, as shown in the figure above of the formation of a Bose-Einstein condensate as temperature of an atomic gas is reduced.
The lowest temperature experiments at present are those involving quantum atomic gases. To carry out such experiments requires the capability to trap, cool, and examine a collection of individual atoms. Unfortunately, atom traps degrade both the ultimate temperature that can be achieved and the uniformity of the trapped system.
Today's state-of-the-art atom traps are based on gravitomagnetic balance. Diamagnetic atoms are repelled from magnetic fields, so that when placed in a magnetic field gradient, the atoms will sink to a level where the upward force from the magnetic interaction just balances the pull of gravity. A gravitomagnetic trap is also designed so that the magnetic field is smaller in the center of the trap than at the edges, so that the atoms are also confined in the horizontal plane.
It is clear that the magnetic interactions of the various atoms in such a trap are not uniform, especially when defects in the production and operation of the trap magnets are taken into account. As a result, any system being studied is not the uniform material usually assumed to make analysis of its properties easier. In addition, any fluctuations or other changes in the magnetic field will tend to make the trapped atoms move faster, which is equivalent to an increase in temperature. Because of such effects, the lowest temperature reached to date in a quantum atomic gas is about 0.45 nK, in a tour-de-force experiment carried out at MIT.
NASA's Cold Atom Lab is intended to break the temperature barrier, offering the chance to carry out experiments on quantum gases at temperatures as low as a few pK (picoKelvin). NASA asked a seemingly stupid question: Why do we need a trap for ultracold experiments on atomic gases?
This question illuminated a fundamental turning point. If the atoms are sufficiently cold, maybe trapping isn't needed. A typical experimental sample of trapped atoms is a few mm on a side. With a sample temperature of 1 K, untrapped atoms would escape from the sample volume in well under a millisecond, nowhere near enough time to carry out the desired experiments. At 1 nK, however, atoms would remain in the experimental volume for around five seconds. At 1 pK, the typical escape period would be more like three minutes, even ignoring any interactions between the atoms. Highly accurate and meaningful experiments can easily be carried out in a handful of seconds, making trapping the atoms within the active volume of the experiment needless.
While there may not be much need to trap atoms at the lowest temperatures (leaving the option of using a trap in between experiments), there is still gravity to deal with. On Earth, the atoms would fall away from the experimental sample volume within 25 milliseconds or so. The atoms would also gain very large amounts of kinetic energy compared to their thermal movements as they fall, leading to a rather confusing experiment.
The solution for lower temperatures? Put the quantum atomic gas laboratory into orbit. At sufficiently low temperatures traps are not needed, and neither is a device to support the atoms against gravity.
The result is NASA's imaginatively named Cold Atom Lab, which will be launched to be installed in the International Space Station in 2016. One of the few science experiments which requires the specialized environment and infrastructure of the ISS, the Cold Atom Lab will pioneer new techniques for analyzing, controlling, and utilizing novel ultracold quantum phenomena. These new capabilities will shed more light on known ultracold phenomena, such as matter-wave interferometry and Bose-Einstein condensates. Also, folklore reports that many surprises lurk in the dark and the cold.
Source: NASA
Scientists announce breakthrough in quest for fusion power
 A metallic case called a hohlraum holds the fuel capsule for the NIF experiments (Photo: Eduard Dewald/LLNL) In a perfect example of beating swords into plowshares, a team of scientists at the Lawrence Livermore National Laboratory's (LLNL) National Ignition Facility (NIF) in California reached a milestone in the quest for practical fusion power using a process designed for the development and testing of nuclear weapons. The announcement in the February 12 issue of Nature claims that the team used the world’s most powerful laser barrage to produce a controlled fusion reaction where more energy was extracted from the fuel than was put into it. If there is an ultimate engineering dream, then nuclear fusion is about as close as close as one can get. By literally harnessing the power of the stars, it holds the promise of what is, for all practical purposes, unlimited clean energy. Since man-made fusion was first demonstrated in 1951 with a boosted fission weapon , scientists and engineers have worked on some way to produce a practical fusion reactor instead of a hydrogen bomb. The story of the fusion reactor is one of both great progress, but also constant frustration. When work began, the first reactor was predicted to be 25 years away. Since then and up until today, it’s still 25 years away. That’s because although nuclear fusion is relatively simple in theory, getting a controlled reaction started outside of the heart of a star is extremely difficult. The trick is to reach the “ignition” point, where the energy released by the reactor is greater than what’s put into it and the reaction becomes self-sustaining. A fusion reactor works by simulating the conditions inside the Sun. Put simply, hydrogen atoms fuse in the Sun because its huge mass squashes the atoms together to form helium, releasing huge amounts of energy as the strong nuclear force that keeps them apart is overcome. A hydrogen bomb does the same thing, only with a fission bomb creating the necessary conditions for a millionth of a second.  A fusion reactor creates the right pressures and temperatures by taking an ionized plasma of the hydrogen isotopes deuterium or tritium and squeezing it using magnetic fields or lasers to set off the reaction. Not surprisingly, this requires huge amounts of energy, which set off various processes that heat the plasma to incredible temperatures. The NIF breakthrough isn’t ignition, but it is a significant waypoint. The NIF team achieved what is called a “fuel gain”. Using an array of 192 high-energy lasers aimed at one tiny plastic sphere filled with a mixture of deuterium and tritium, the scientists subjected the droplet of cryogenic fuel to 1.9 megajoules of light to produce sun-like temperatures for a tiny fraction of a second. The result was a fusion reaction where the energy put into the fuel was exceeded by the energy that came back out – something that until now has never been achieved anywhere outside of a star or a hydrogen bomb, and is ten times greater than anything previously seen. The key to this is something called "boot-strapping". Boot-strapping works by using alpha particles, which are helium atoms stripped of their electrons. Normally, when a fusion reaction produces such particles, they shoot off, carrying energy with them. In bootstrapping, the deuterium/tritium mixture is made to capture the alpha particles, which heats the plasma more and releases more alpha particles to increase the reaction. According to the team, the key to boot-strapping was to keep the plastic shell that contains the fuel from disintegrating during compression under a high-energy laser pulse by altering the timing of the pulse to "fluff up" the ablative plastic, making it more resilient. The team believes that this disintegration in previous tests hindered the reaction and by modifying the laser they were able to prevent this. "What's really exciting is that we are seeing a steadily increasing contribution to the yield coming from the bootstrapping process we call alpha-particle self-heating as we push the implosion a little harder each time,” says Omar Hurricane, lead author of the team’s report. Ironically, power generation wasn’t the team’s primary goal. The NIF is designed to provide hard data for computer models that simulate the explosion of a nuclear warhead as part of the US program to produce new warheads and to ensure that the existing stockpiles remain safe and reliable. Up until the comprehensive nuclear test ban treaty, this would have been done using underground test explosions, but the US government now relies on lasers and supercomputers for the National Nuclear Security Administration's Stockpile Stewardship Program. Eventually, the scientists hope the boot-strapping process will lead to ignition, but that remains in the future, as does practical application in a working commercial reactor. Currently, the experiment is only able to produce of net gain of about one percent. "There is more work to do and physics problems that need to be addressed before we get to the end," said Hurricane, "but our team is working to address all the challenges, and that's what a scientific team thrives on". The team’s results were published in the journal Nature . Source: Lawrence Livermore National Laboratory
|
Essential Nutrients in the World's Healthiest Foods
Essential nutrients are nutrients that your body can't make on its own. How these nutrients are introduced into your body may have a great impact on how well they are utilized. Nutrients do not work alone but in concert (synergistically) with other nutrients. The benefit of deriving nutrients from eating fresh whole foods such as those included on the list of the World's Healthiest Foods is that they provide not only an abundance of individual nutrients but also the variety necessary for their optimal function. This section is designed to inform you about the function of the various nutrients and which of the World's Healthiest Foods are the richest source for each of them.
Assinar:
Postagens (Atom)