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2013職稱英語衛(wèi)生類B試題解析（3）
Human Heart Can Make New Cells
Solving a longstanding mystery, scientists have found that the human heart continues to generate new cardiac cells throughout the life span, although the rate of new cell production slows with age.
The finding, published in the April 3 issue of Science, could open a new path for the treatment of heart diseases such as heart failure and heart attack ,experts say.
"We find that the beating cells in the heart, cardiomyocytes, are renewed, " said lead researcher Dr. Jonas Frisen, a professor of stem cell research at the Karolinska Institute in Stockholm, Sweden. "It has previously not been known whether we were limited to the cardiomyocytes we are bom with or if they could be renewed." he said.
The process of renewing these cells changes over time, Frisen added. In a 20-year-old, about 1 percent of cardiomyocytes are exchanged each year, but the turnover rate decreases with age to only 0. 45 percent by age 75.
"If we can understand how the generation of new cardiomyocytes is regulated , it may be potentially possible to develop pharmaceuticals that promote this process to stimulate regeneration after for example, a heart attack, " Frisen said.
That could lead to treatment that helps restore damaged hearts.
"A lot of people suffer from chronic heart failure," noted co-author Dr. Ratan Bhardwaj.
Ratan Bhardwaj, also from the Karolinska Institute. " Chronic heart failure arises from heart cells dying, "he said.
With this finding, scientists are "opening the door to potential therapies to having ourselves heal ourselves, " Bhardwaj said. " Maybe one could devise a pharmaceutical agent that would make heart cells make new and more cells to overcome the problem they are facing."
But barriers remain. According to Bhardwaj , scientists do not yet know how to increase heart cell production to a rate that would replace cells faster than they are dying off, especially in older patients with heart failure. In addition, the number of new cells the heart produces was estimated using healthy hearts-whether the rate of cell tumover in diseased hearts is the same remains unknown.
1. The human heart stops producing cardiac cells
A. when a person becomes old
B. as soon as a person gets sick
C. immediately after a person is born
D. once a person dies
2. The finding could prove to be useful to
A. the analysis of cardiac cells
B. the prevention of chronic diseases
C. the treatment of heart disease
D. the study of longstanding mysteries
3. In people in their mid-70s, only 0. 45 percent of cardiomyocytes _ .
A. are still functional
B. are reduced each year
C. are replaced each year
D. are damaged each year
4. Chronic heart failure is attributed to
A. the dying heart cells
B. the effect of pharmceutical
C. the weight of a patient
D. the life span of a person
5. It is not known yet if the rate of cell turnover in diseased hearts
A. is high enough to replace cells faster than they're dying off
B. is of any use to researchers
C. is the same as that in healthy hearts
D. changes over time
參考譯文及答案：
帕金森氏綜合征
帕金森氏綜合征會影響你行動的方式。當大腦的某些神經(jīng)細胞出現(xiàn)問題時，這種疾病就會爆發(fā)。正常情況下，這些神經(jīng)細胞會產(chǎn)生一種叫多巴胺的重要的化學物質(zhì)。多巴胺會向你的大腦中控制行為的部分發(fā)出信號。它使你的肌肉能活動自如，做你想做的事。一旦你患上帕金森氏綜合征，這些神經(jīng)細胞就會出問題。接著，你不再有足夠的多巴胺，并開始行動困難。
沒人知道什么促使這些神經(jīng)細胞出現(xiàn)問題。但是，科學家們做了很多研究來尋找答案。
他們研究了很多可能的病因，包括年齡老化和環(huán)境污染。在某些人身上，似乎是不正常的基因導致了帕金森氏綜合征的發(fā)病。但是目前沒有足夠的證據(jù)表明它是遺傳的。
顫抖可能是你注意到的第一個癥狀。雖然并不是每一位患者都有這種癥狀，但是它是這種疾病最常見的表現(xiàn)之一。更重要的是，并不是每一個顫抖的人都患有帕金森氏綜合征。顫抖往往從一條胳膊，一條腿或身體的一側開始。這種情況在你醒著但是沒有移動受影響的胳膊或者腿時更嚴重些。但是當你移動肢體或睡眠時情況會有所緩和。不久，帕金森氏綜合征會影響你的全身肌肉，導致吞咽困難及便秘。在疾病后期，患這種病的人可能會有表情僵化，言語困難及其他一些問題。一些患者也會思維退化。
現(xiàn)在還沒有辦法治愈帕金森氏綜合征。但是有幾種藥物能控制癥狀并讓患者好受些。如果你的癥狀很輕微的話，你可能根本不需要治療。直到你的癥狀影響到你的日常生活方式時，醫(yī)生才會給你開藥。伴隨著你的癥狀的惡化，醫(yī)生將會調(diào)整用藥。為了得到最好的療效你得吃幾種藥。
1.D [解析]根據(jù)是第一段中：…the human heart continues to generate new cardiac cells throughout the life span。在人的整個生命進程中，其心臟不時產(chǎn)生新的心肌細胞。言外之意，這個過程直到人死才會停止。
2.C [解析]根據(jù)是第二段中：The finding，…，could open a new path for the treatment of heart diseases 這一研究成果將為心臟病的醫(yī)治開拓新的途徑。
3.C[解析]第四段說，一個人20歲時，其每年被更替的心肌細胞為1%，隨著年齡的增長，該更替率( turnover rate)不斷下降，等到75歲時，只有0.45%。
4.A [解析]倒數(shù)第三段說：Chronic heart failure arises from heart cells dying。慢性心衰是由心肌細胞死亡導致的。
5.C[解析]最后一句說：心臟產(chǎn)生的新細胞的數(shù)量是按照健康心臟計算的，而有心臟病的細胞更替率是否與健康心臟相同還不得而知。
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