卫生类：阅读理解Human Heart Can
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 born with or if they could be renewed1，" he said.
The process of renewing these ceils 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， also from the Karolinska Institute. "Chronic heart failure arises from heart cells dying2，" he said. from www.yingyukaoshi.com
With this finding， scientists are "opening the door to potential therapies to having ourselves3，" 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 turnover in diseased hearts is the same remains unknown.
词汇
Longstanding adj. 为时甚久的turnover n. 更替率
Cardiac adj. 心脏的pharmaceutical n. 药物
cardiomyocyte n. 心肌细胞therapy n. 疗法、治疗
注释
1. It has previously not been known whether we were limited to the cardiomyocytes we are born with or if they could be renewed: 早前并不清楚人们是否局限于出生时所具有的细胞还是说这些细胞可以被更新。
2. Chronic heart failure arises from heart cells dying: 慢性心衰是由心肌细胞死亡导致的。
3. With this finding， scientists are "opening the door to potential therapies to having ourselves heal ourselves": 有了这一发现，科学家们正在打开让我们自愈的潜在疗法的大门。