VOA慢速英語:一種乳腺癌藥物對艾滋病病毒也有一定的抗感染作用
From VOA Learning English, this is Science in the News. I’m Faith Lapidus.
And I’m Steve Ember. Today on the program, we tell about internationalefforts to fight a health threat in the West African nation of Guinea. Then, wereport on a finding that cold air might be good for your health. But first, wereport on a medical discovery. American researchers say a drug used to treatbreast cancer may help people who have AIDS or HIV, the virus that causesthe disease.
Breast Cancer Drug May Help HIV/AIDS Patients
A drug used to treat breast cancer may soon have another use. Researcherssay the drug could be helpful as a weapon against a fungal infection that killsmore HIV/AIDS patients than the disease tuberculosis. The possible new usefor tamoxifen was discovered as part of an investigation of older, alreadyapproved drugs. The makers of these drugs have sought and receivedapproval from United States government agencies to sell their products to thepublic.
Health experts estimate that a fungus called Cryptococcus infects about onemillion people worldwide every year. The fungal infection is calledCryptococcosis. It is especially deadly for people living with AIDS, AcquiredImmune Deficiency Syndrome. Most of the infections take place in Africancountries south of the Sahara Desert. Ninety percent of the people who haveAIDS live in those countries.
Damian Krysan is an infectious diseases specialist at the University ofRochester in New York State. He says Cryptococcosis can lead tomeningitis, a life-threatening infection of the covering of the brain and spinalcord.
“It currently kills on the order of three-quarters of a million people a year,primarily again in resource-limited regions with high rates of HIV/AIDS.”
Two costly drugs are commonly used to treat the fungal infection. But theyare not commonly available in developing countries. And they are difficult togive to patients, because they must be injected into a person’s blood. Expertssay that even under the best conditions, 10 to 20 percent of those who receivethis treatment will die. Another drug is often used in poor countries to fightCryptococcosis. But the drug only slows the growth of the infection.
Some researchers are investigating whether drugs already approved for onecondition might be useful against another. Dr. Krysan and other researchersexamined about 2,000 drugs and combinations of drugs for ones that could killCryptococcus.
They found one – tamoxifen, a drug that has been used for years to treatwomen with breast cancer. Dr. Krysan says tamoxifen is not pricey andseems to help patients in a number of ways.
“Can be given orally to patients, which is what we needed. And Cryptococcuscauses a brain infection essentially. And so we needed that drug to get to thebrain. And tamoxifen actually crosses into the central nervous system veryeffectively and even accumulates to levels above what we see in the blood.”
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Dr. Krysan published a report on his findings in the journal mBio. He saystamoxifen is most effective against the fungal infection when it is combinedwith the drug that is already used to treat Cryptococcosis in poor countries.
More tests are still needed. But because both drugs are already approved,human testing will follow soon.
Aid Groups in Guinea Fighting Measles Outbreak
Mass emergency vaccination programs were launched in Guinea recently tocontrol a growing health threat -- measles. Doctors Without Borders and theUnited Nations Children’s Fund announced the vaccination campaigns lastmonth. The two groups planned to work with Guinea’s Ministry of Health tovaccinate more than two million children against measles. All the boys andgirls are between the ages of six months and 10 years.
The World Health Organization warns that measles is one of the mostlyhighly-infectious diseases. WHO experts say measles is a leading cause ofdeath among children. The cause is a fast-spreading virus.
The measles outbreak in Guinea began in December. A short time later, thegovernment declared measles an epidemic. This means it has infected manypeople over a short period. The last measles outbreak in Guinea was in 2009. At that time, the disease infected more than 4,000 children and caused10 deaths.
Most cases of measles are curable. But health experts say vaccination is thebest way to keep the number of deaths low.
In February, Doctors Without Borders reported that not enough children hadreceived vaccinations that include protection against measles. It said fewerthan 80 percent of children living in the capital Conakry had received suchvaccines. Only 37 percent of all children in Guinea were vaccinated.
Dr. Renaldo Ortunio works for Doctors Without Borders. He says even asingle case of measles is one too many.
“Measles is a preventable disease by vaccine, so you shouldn’t have anepidemic, an outbreak in this country. But unfortunately, there are someweaknesses at the Ministry of Health, in the regular vaccinations and ofcourse, with this lack of vaccination among children, we see an outbreakevery three to four years, which is the case currently in Conakry.”
Health officials have been urging parents to watch their children for signs ofmeasles: high body temperature, redness in the eyes, white areas on themouth, and skin discoloration on the face and neck.
Shivering Could Help Burn Body Fat
North America was in a deep freeze this winter. Cold air from the Arctic led torecord low temperatures in some areas. But now, a new study has found thatall that cold air may actually be good for your health.
It was so cold in Chicago, Illinois last month that people were being warned tostay inside. Paige Worthy was born and lives in the place that Americans callThe Windy City. She says this was the worst winter she can remember.
“It actually hurt to breathe in because the air is so cold that I actually have tocover my mouth with a scarf to keep my lungs from actually hurting.”
Shivering is an involuntary response to cold. It is the subject of a new studypublished in the journal Cell Metabolism. Researchers say they found thatshivering or shaking causes the body to release a natural hormone calledirisin. The hormone activates brown fat -- the good fat in your body that burnscalories and helps to support weight loss.
Francesco Celi of Virginia Commonwealth University was the lead writer of areport about the study. He says irisin has another important role.
“Indeed the purpose of brown fat is maintaining the core temperature, so thetemperature of the body whereby all the vital functions can be active andnormal.”
Dr. Celi worked with researchers at the US National Institutes of Health, inBethesda, Maryland. They already knew the body produces irisin when we dophysical exercise. When we exercise, our muscles contract, or change insize, like they do when we shiver. The NIH researchers believe humanancestors developed the ability to shiver as a way to survive cold weather.
“This is the last ditch before going into hypothermia and having severemetabolic and life-threatening consequences.”
The researchers studied hormonal changes and how the body uses energy in a group of volunteers who exercised. The volunteers were then asked to lieunder cooling blankets -- where temperatures were slowly reduced to 12degrees Celsius.
“Most of our volunteers shivered at that time and the shivering was anywherebetween five and 10 minutes, not more. And, again we drew the blood beforeand after the study.”
The volunteers’ bodies produced irisin, but with some surprises.
“The amount of increase in irisin was almost identical to what we observedafter one hour of exercise. This first set of experiments validated our initialhypothesis, whereby the maximum stimulation of irisin is probably shivering.”
Dr. Celi says understanding how irisin activates brown fat could lead to newdrugs to fight diabetes or help overweight individuals.
“It is a short-term effect. We do not know yet the long term consequences ofthese interventions. So, studies need to be performed to address this veryquestion. We do not know if this is advantageous, which individuals would bemore able to gain from intervention.”
Back in Chicago, Paige Worthy is pleased to know that shivering may have aphysical benefit. Ms. Worthy works as a fitness trainer. She helps peopleimprove their physical condition. She is not sure she will urge her fitnessstudents to be cold and shiver.
“As a newly-minted spinning instructor, I guess I would say that there are risksthat go along with every exercise and every weight loss regimen, but thisseems like kind of a perilous way to approach your weight loss, if it is going to be this cold.”
Dr. Celi agrees. Just because shivering and exercise have similar effects on the body, he says, that does not mean standing in the cold should replacephysical activity.
This Science in the News was based on reports from VOA reporters JessicaBerman, Jennifer Lazuta and Rosanne Skirble. The program was written byChristopher Cruise, and produced by June Simms. I’m Faith Lapidus.
And I’m Steve Ember. Join us again next week for more news about scienceon the Voice of America.
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