South Koreas stem cell scientists have cloned a dog, smashing another biological barrier a
A、buying stocks for inventory when investors want to sell.
B、selling stocks from inventory when investors want to buy.
C、doing both of the above.
D、doing neither of the above.
As expected, the most rigid opposition has come from the Catholic Church, which considers the embryo to be a living person from the moment of conception. Cloning aside, even research involving "spare" embryos (created for infertility treatments but not used. is condemned because it is morally wrong to use a person for the benefit of someone else. At the opposite end of the spectrum (范围)lie the hardcore utilitarians (功利主义)of science and business, who are generally astute (精明的)enough not to announce their politically incorrect views: namely that the embryo isjust another batch of cellular sludge (淤积;淤沉)that can and should be used like any other biological resource in the pursuit of medical research.
1.The purpose of therapeutic cloning is to.()
A.produce people
B.commercialize stem cells
C.treat various diseases
D.clone human embryo in Dolly
2.What triggered the debate across the industrial countries?()
A.The commercialization of cloned human embryos.
B.Legalizing the creation of cloned human embryos in Britain.
C.A theoretical flaw in the experiment of human embryos cloning.
D.The European Parliament's harsh criticism on the UK's decision.
3.In the 1990s the British researchers use embryos basically to.()
A.harvest stem cells
B.reform. the system of medical care
C.treat infertility and detect birth defects
D.study the possibility of organ transplants
4.The Catholic Church argue against human embryos cloning because.()
A.cloning creates spare embryos
B.it considers the embryo to be a living person
C.it may lead to reproductive cloning
D.it's morally wrong to use a person for the benefit of another one
5.The utilitarians of science and business think.()
A.human embryos cloning is a hard choice
B.it's politically incorrect to clone human embryos
C.the embryos should be used like any other biological resource
D.human embryos are important samples in the pursuit of medical research
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 born with or if they could be renewed," 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 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 turnover in diseased hearts is the same remains unknown.
The human heart stops producing cardiac cells____________. 查看材料
A.when a person is born
B.when a person becomes old
C.when a person gets sick
D.when a person dies
Though _____ experience, she eventually got the chance of working in Dell Company. |
[ ] |
A. lack of B. lacked C. lack in D. lacking |
A.Diversified.
B.Stable.
C.Thrilling.
D.Prosperous.
A.1
B.2
C.3
D.4
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