在英语越来越重要的21世纪，英语成了大学生顺利进入社会的通行证，为了帮助同学们更好地学习英语，特提供以下资料：
Five cloned piglets, genetically modified so that their organs are much less likely to be rejected by a human donor recipient, have been born in the US
在美国已降生了5只基因改良的克隆小猪,这使得它们的器官在植入人体时发生排异反映的可能性大为缩小。
More than 62,000 people in the US alone are waiting to receive donated hearts, lungs, livers, kidneys and pancreases. The number of human donors falls far short of demand. Pig organs are of a similar size to human organs, and some scientists hope they might be used to help meet the shortfall. But previous attempts to transplant unaltered pig tissue into humans have failed, due to immune rejection of the tissue.
仅仅在美国就有6.2万多人在期待被捐募出的心脏、肺、肝脏、肾脏和胰脏,器官捐募者的人数远远知足不了要求。猪的器官巨细与人的器官相似,一些科学家但愿它们可用于填补器官欠缺问题。可是,因为种间组织免疫系统的彼此排异反映,畴前那些用未经改良的猪器官做的移植试验都失踪败了。
The five piglets, born on Christmas Day, lack a gene for an enzyme that adds a sugar to the surface of pig cells. The sugar would trigger a patient's immune system into launching an immediate attack.
圣诞节出生的这5只小猪,贫窭一种使猪的细胞概况加上某种糖类蜗质的酶的基因。恰是这种糖激发病人的免疫系统当即发生免疫排异反映。
"This advance provides a near-time solution for overcoming the shortage of human organs for transplants, as well as insulin-producing cells to cure diabetes," says David Ayares, vice president of research at PPL Therapeutics, US division, where the pigs were created. " This is the key gene for overcoming the early stage of rejection."
培育出这些小猪的PPL医疗公司美国分部的研究项目副总裁大卫·阿亚里斯说:"这项科研进展实时解决了今朝所面临的人体器官移植来历欠缺问题,以及治疗糖尿场所需的出产胰岛素的细胞。这是个解决早期排异反映的关头基因。"
However, scientists warn that much more work is necessary before organs from copies of the pigs could be transplanted into humans. Human genes will need to be added, to prevent rejection of the organ in the long-term. There are also conerns that pig viruses could infect organ recipients.
可是,科学家们提醒说,在由克隆猪所供给的器官能够顺遂植入人体以前,还有良多必需的工作要做。可能会需要再加上人体的基因以使这些器官能够持久免于排异反映。猪的病毒对接管器官的人的传染,也是个值得关注的问题。
Cloning techniques were vital to the production of the pigs. Genes can only be knocked out in a single cell. Cloning of these single cells then allowed the creation of a whole animal in which the gene was knocked out in every cell. But the PPL researchers have succeeded in knocking out only one copy of the gene for the enzyme, called alpha 1，3 galactosyl transferase. The team will now attempt to knock out both copies of the gene.
克隆手艺是培育这些猪的关头。基因的去除只有在单个细胞中才能进行。克隆这些单细胞然后再将其培育成一只完整的动物,这样动物身上的每个细胞中的这种基因就都被去除了。可是,PPL医疗公司的研究人员只是成功地去除了发生这种叫α?1,3半乳糖转移酶的基因的一个副本。他们在试图将这个基因的两个副本都去除。
"There will also be other genes we will incorporate into our program," Ayares says. "We don't think that one gene is going to produce an organ that's going to be the end-all for transplantation. We're going to have to add two to three human genes as well."
阿亚里斯说:"我们的项目也会搜罗其他基因,我们感受把握一个基因培育的器宦海不能彻调整决器官移植面临的所有问题。我们得再插手两到三小我类基因的研究。"
The team will also conduct tests to investigate whether so-called porcine endogenous retroviruses (PERVS)from the pigs could infect human cells in culture. But Ayares hopes that organs created from PPL pigs could be transplanted into patients within five years.
该小组还将经由过程尝试验证是否猪身上的内素性逆转滤过性病毒(一种致癌病毒)会在移植培育过程中传染到人身上。但阿亚里斯但愿在5年内PPL医疗公司培育的器官能够被移植到人身上
"But although a lot of the stem cell work is very exciting, we're still very far off being able to grow an organ in a culture dish," says Julia Greenstein of Immerge Bio Therapeutics in Charlestown, US, who is working on creating similar knock-out pigs with researchers at the University of Missouri.
就职美国查尔斯城浸没生物医疗公司的朱利娅·格林斯坦,正在密苏老迈学和同事们从事着近似的研究，即培育去除某种基因的小猪。她说:"尽管干细胞研究的良多工作令人很是感动,但在培育器中成功地培育出器官还为时过早。"