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  3. The complications frequently accompanying diabetes, such as impairment of vision and of kidney function, are now thought to resu

The complications frequently accompanying diabetes, such as impairment of vision and of kidney function, are now thought to resu

admin2015-01-31  23
问题     The complications frequently accompanying diabetes, such as impairment of vision and of kidney function, are now thought to result from the lack of continuous control of blood glucose concentrations. The healthy pancreas, in response to increases in blood glucose concentration, releases small quantities of insulin throughout the day and thereby maintains the concentration within physiological limits(nomoglycemia). But the diabetic generally receives only one large dose daily. The diabetic’ s blood glucose concentration can thus fluctuate greatly during the interval between doses, and it has been suggested that the complication result from the periods of high concentrations of blood glucose(hyperglycemia). Many investigators thus believe that restoration of normoglycemia might halt the progression of such complications and perhaps even reverse them.
    There are three primary techniques that have been investigated for restoration of normoglycemia. They are: transplantation of whole, healthy pancreases; transplantation of islets of Langerthan, that portion of the pancreas that actually secretes insulin, and implantation of artificial pancreases. There has, in fact been a great deal of success in the development of these techniques and each seems, on the whole, promising. Nonetheless, it will undoubtedly be many years before any one of them is accepted as a treatment for diabetes.
    To many people, the obvious approach would seem to be simply to transplant pancreases from cadavers in the same manner that kidneys and other organs are routinely transplanted. That was the rationale in 1966 when the first recorded pancreas was performed. Between 1960 and 1975, there were forty-six pancreas transplants in forty-five other patients in the United States and five other countries. But only one of these patients is still alive with a functioning graft and surgeons have found that the procedure is not simple as they once thought.
    The surviving patient has required no insulin since the operation. Another patient survived 638 days without requiring insulin. And one patient survived a transplantation for more than a year, but died when he chose not to take immunosuppressive drugs. These results, though meagre, suggest that the procedure has the potential for success.
    The rest of the patients, however, either rejected the transplant or died within a short period. There does not appear to be any technical problem with the procedure. Rather, most of the patients were already so severely debilitated by the complications of diabetes that they could not withstand the surgery and the immunosuppressive regimen required to prevent rejection. More than half of the patients, furthermore, also required a kidney transplant. Most investigators now agree that the simultaneous transplantation of both organs is too great a shock to the patient and greatly increases the total risk.
Which of the following best states one of the main conclusions of the text?
选项 A、Although the techniques for pancreas transplants appear to be theoretically correct, there are problems that must be solved before the operation can be used as a treatment for diabetes.
B、Although the techniques for pancreas transplants are still being developed, the experimental results show that the operation will be a successful treatment for diabetes in the near future.
C、Although pancreas transplants are reliable, many diabetics are reluctant to undergo the operation because of the side effects of immunosuppressive drugs.
D、Although pancreas transplants alone are not generally successful, the operation can be used in conjunction with other procedures to treat diabetes.
答案A
解析 主旨题。本章第一段首先引出话题．糖尿病的并发症可能就是源于这些高血糖浓度时期。第二段是本篇文章的中心段，指出为了恢复正常的血糖浓度．已对三种主要的技术进行了研究，而后文是对研究的简介。所以本题的定位点在第二段There has，in fact been a great deal of success in the development of these techniques and each seems，on the whole，promising．Nonetheless，it will undoubtedly be many years before any one of them is accepted as a treatment for diabetes．“事实上。这些技术的发展都获得了成功，而且从整体上讲，每种技术都大有希望。然而，毫无疑问地，在任何一种技术被接受用作糖尿病患者的治疗手段之前，还会有很多年的时间。”和A选项表达一致。所以答案选A。
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