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Scientists seeking view new ways to repair damaged arteries and ailing hearts have coaxed stem cells from a human embryo into forming tiny blood vessels. It’s the first time human embryonic stem cells have been nurtured to the point where they will organize into blood vessels that could nourish the body, according to Robert Langer, leader of a laboratory team at the Massachusetts Institute of Technology. But it isn’t likely to be the last, as scientists pursue research into uses for stem cells despite debate over the ethics of using the cells. The new development was reported in Tuesday’s online issue of proceedings of the National Academy of Sciences. Dr. John Gearhart of the Johns Hopkins Schools of Medicine said research was a “nice illustration” of how stem cells can serve as a source of various types of cells, in this case for blood vessels. “I think this is terrific” said Gearhart, who was not part of the research team. “It’s another good example of the isolation of an important cell type from human embryonic stem cells.” “These are the kinds of papers we are going to see a lot of,” Gearhart added. Langer said the work showed that endothelial cells could be made from human embryonic stem cells. Endothelial cells have veins, arteries and lymph tissue. They are key to the structures that carry blood throughout the body. He said that if the technique we refined, scientists would eventually be able to make in the laboratory blood vessels that could be used to replace diseased arteries in the body: “There are thousands of operations a year now where doctors take vessels from one part of the body and transplant them to another,” said Langer. Eventually, he said, such vessels might be made outside the body from embryonic stem cells. Langer said endothelial cells also might be used to restore circulation to cells damaged by heart attacks. He said the processed stem cells may be able to reestablish blood flow to hearts failing due to blocked arteries. The research was conducted under a private grant, but Langer said the cell culture used is one of 61 worldwide that have been approved by the National Institutes of Health for federally funded research. The use of embryonic stem cells is controversial because extracting the cells kills a living human embryo. President Bush last summer decided that federal funding would be permitted only for stem cell cultures that already existed and were made from embryos that were to be discarded by fertility clinics. The aim was to prevent further killing for research purposes of other human embryos. Langer said his lab will seek federal money to continue research using the same stem cell cultures, which were obtained from the Ram Bam Medial Center in Haifa, Israel. Embryonic stem cells are the ancestral cells of every cell in the body. In a developing embryo, they transform into cells that make up the organs, bone, skin and other tissues. Researchers hope to direct the transformation of such cells to treat ailing hearts, livers, brains and other organs. Langer said his team cultured the cells in such a way that they were allowed to develop into the various types of cells that are precursors to mature tissue. From this colony, the researchers extracted cells that were following a linage that would lead to mature endothelial cells. These were further cultured and some eventually formed primitive vascular structures.
[1] Which of the following statements does not follow from the passage?
(1) Fertility clinics collect human embryos.
(2) Human embryos are destroyed is stem cell research
(3) Stem cells are being researched especially for forming blood vessels
(4) Stem cell research uses federal funding[2] Which of the following would be made redundant by the research mentioned?
(1) Sourcing embryonic cells from fertility clinics.
(2) Transplanting of blood vessels from one part to another.
(3) Cardiac operations necessitated by heart attacks.
(4) Performing open heart surgeries.[3] Stem cell research involves?
(1) cell cultures from various genetically altered embryos.
(2) Killing of a live human embryo
(3) wastage of embryo by fertility clinics
(4) genetic cloning of abilitiesasked in NMAT
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213.
In many underdeveloped countries, the state plays an important and increasingly varied role in economic development today. There are four general arguments, all of them related, for state participation in economic development. First, the entrance requirements in terms of financial and capital equipment are very large in industries, and the size of these obstacles will sere as barriers to entry on the part of private investors. One can imagine that these obstacles are imposing in industries such as steel production, automobiles, electronics, and parts of the textiles industry. In addition, there are what Myint calls “technical indivisibilities in social overhead capital.” Public utilities, transport, and communication facilities must be in place before industrial development can occur, and they do not lend themselves to small-scale improvements. A related argument centres on the demand side of the economy. This economy is seen as fragmented, disconnected, and incapable of using inputs from other parts of the economy. Consequently, economic activity in one part of the economy does not generate the dynamism in other sectors that is expected in more cohesive economies. Industrialization necessarily involves many different, sectors; economic enterprises will thrive best in an environment in which they draw on inputs from related economic sectors and, in turn, release their own goods for industrial utilization within their own economies. A third argument concerns the low-level equilibrium trap in which less developed countries find themselves. At subsistence levels, societies consume exactly what they produce. There is no remaining surplus for reinvestment. As per-capita income rises, however, the additional income will not be used for saving and investment. Instead, it will have the effect of increasing the population that will eat up the surplus and force the society to its former subsistence position. Fortunately, after a certain point, the rate of population growth will decrease; economic growth will intersect with and eventually outstrip population growth. The private sector, however, will not be able to provide the one-shot large dose of capital to push economic growth beyond those levels where population increases eat up the incremental advances. The final argument concerns the relationship between delayed development and the state. Countries wishing to industrialize today have more competitors, and these competitors occupy a more differnentiated industrial terrain than previously. This means that the available niches in the international system are more limited. For today’s industrializers, therefore, the process of industrialization cannot be a haphazard affair, not can the pace, content, and direction be left, solely to market forces. Part of the reason for strong state presence, then, relates specifically to the competitive international environment in which modern countries and firms must operate.
[1] What does the author suggest about the “technical indivisibilities in social overhead capital”?
(1) It is a barrier to private investment
(2) It enhances the development effects of private sector investment
(3) It leads to rapid technological progress
(4) It can prevent development from occurring[2] According to the passage, the “low-level equilibrium trap” in underdeveloped countries results from
(1) the inability of market forces to overcome the effects of population growth
(2) intervention of the state in economic development
(3) the tendency for societies to produce more than they can use
(4) the fragmented and disconnected nature of the demand side of the economy.[3] According to the author, a strong state presence is necessary
(1) to provide food for everyone
(2) to provide the capital needed to spur economic growth
(3) to ensure the livelihood of workers
(4) to ensure that people have more than what is necessary for subsistence[4] In the passage, the world ‘cohesive’ means
(1) containing many cohorts or groups
(2) modern and competitive
(3) naturally and logically connected
(4) containing many different sectors[5] In the passage, the word ‘imposing’ means
(1) Something huge
(2) something that strikes a pose
(3) something that obtrudes on others
(4) to act with a delusive effectasked in NMAT
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214.