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More about Alzheimer’s Disease
Scientists have developed skin tests that may be used in the future to identify people with Alzheimer’s disease and may ultimately allow physicians to predict who is at risk of getting this neurological disorder.
The only current means of diagnosing the disease in a living patient is a 1ong and expensive series of tests that eliminate every other cause of dementia.
“Since A1ois Alzheimer described the disease nearly a century ago，people have been trying to find a way to accurately diagnose it in its early stages，”said Patricia Grady，acting director of the National Institute of Neurological Disorders and Stroke in Bethesda，Maryland.“This discovery，if confirmed，could prove a big step forward in our efforts to deal with and understand the disease.”
A1zheimer，s is the single greatest cause of mental deterioration in older people，affecting between 2.5 million and 4 million people in the United States alone．The devastating disorder gradually destroys memory and the ability t0 function，and eventually causes death．There is currently no known treatment for the disease．
Researches discovered that the kin cells of Alzheimer’s patients have defects that interfere with their ability to regulate the now of potassium in and out of the cells．The fact that the cell defects are present in the skin suggests that Alzheimer’s results from physiological changes throughout the body，and that dementia may be the first noticeable effect of these changes as the deflects affect the cells in the brain．scientists said．
The flow of potassium is especially critical in cells responsible for memory formation． The scientists also found two other defects that affect the cells’ supply of calcium，another critical element．
0ne test developed by researchers calls for growing skin cells in a laboratory calture and then testing them with an electrical detector to determine if the microscopic tunnels that govern the now 0f potassium are open． 0pen potassium channels create a unique electrical signature．
A spokesman for the Alzheimer’s association said that if the validity of the diagnostic test can be proven it would he important rlevelopment，but tautioned that 0ther promising tests for Alzheimer’s have been disappointing．
第 46 题 The newly developed skin tests may be used in the future to allow doctors to
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‘Hidden’ Species May Be Surprisingly Common
Cryptic species—animals that appear identical but are genetically quite distant—may be much more widespread than previously thought． The findings could have major implications in areas ranging from biodiversity estimates and wildlife management，to our understanding of infectious diseases and evolution．
Reports of cryptic species have increased dramatically over the past two decades with the advent of relatively inexpensive DNA sequencing technology．Markus Pfenninger and Klaus Schwenk，of the Goethe—Universitat in Frailkfurt，Germany，analyzed all known data on cryptic animal species and discovered that they are found in equal pmponions throughout all major branches 0f the animal kingdom and occur in equal numbers in all biogeographical regions．
Scientists had previously speculated that cryptic species were predominantly found in insects and reptiles．and were more likely to occur in tropical rather than temperate regions．“Species that are seemingly widespread and abundant could in reality be many different cryptic species that have low populations and are highly endangered，”says Pfenninger．Until the genetic information of all species in at least one taxon is thoroughly studied，no one will know just how many cryptic species exist．“It could be as high as 30％．”Pfenninger says．
“I’m extremely surprised by their results，”says Alex Smith of the University of Guelph in Ontario．Canada．“It’s a call to arms to keep doing the broad kind of genetic studies that we are doing．"
Sampling as many individuals as possible．scientists hope to complete work on aU fish and birds in another 5 to 10 years． Once either of these taxonomic groups is completed，Pfenninger says researchers will able t0 decide how many cryptic species exist throughout the animal kingdom．
Examples of cryptic species include the African elephant．A 2001 study found the elephants were actually two genetically distinct，non—interbreeding species，the African bush elephant and the African elephant．The species are currently listed as vulnerable and threatened，respectively，by the World Conservation Union（WCU）．
The reclassifications are more than an academic exercise．They define populations that have evolved independently of each other and whose genetic differences can have significant consequences．
In the early 1900s misidentification of mosquito species based on morphology confused attempts to control malaria in Europe． Ultimately，what was thought to be a single species was actually made up of six sibling species，only three of which transmitted the disease．“The basic unit in biology is always the species．and you have to know what you are dealing with，”Pfenninger says．Much previous research is now no longer used．he says，because it is not clear what species was being studied．
第 36 题 Which of the following about the significance of the research on cryptic species is NOT true？
A．helpfully B．usefully C．1ikely D．readily
Warm people likely to keep cold at bay
Staying positive through the cold season could be your best defense against getting ill，new study findings suggest．In an experiment that exposed healthy volunteers to a cold or flu virus，researchers found that people with a generally sunny disposition were less likely to fall ill．
The findings，published in the journal Psychosomatic Medicine，build on evidence that a “posi-tive emotional style”can help ward off the common cold and other illnesses．Researchers believe the reasons may be both objective as in happiness boosting immune function and subjective as in happy people being less troubled by a scratchy throat or runny nose7.
“People with a positive emotional style. may have different immune responses to the virus．”explained lead study author Dr Sheldon Cohen of Carnegie Mellon University in Pittsburgh．“And when they do get a cold，they may interpret their illness as being less severe．”
Cohen and his colleagues had found in a previous study that happier people seemed less susceptible to catching a cold，but some questions remained as to whether the emotional trait itself had the effect．
For the new study，the researchers had 1 93 healthy adults complete standard measures of personality traits，self-perceived health and emotional “style．”Those who tended to be happy，energetic and easy-going were judged as having a positive emotional style，while those who were often unhappy，tense and hostile had a negative style．
The researchers gave them nasal drops containing either a cold virus or a particular flu virus．0ver the next six days，the volunteers reported on any aches，pains，sneezing or congestion they had，while the researchers collected objective data，like daily mucus production．Cohen and his colleagues found that based on objective measures of nasal woes，happy people were less likely to develop a cold．
第 11 题 According to a study author，when people with a positive emotional style. do get a cold，they may think_______．
According to the article，when people feel too worried or nervous or when they overwork．
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