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101.
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BACKGROUND: Pancreatic cancer is a common cause of mortality in the United States, with an estimated 27,800 people dying of the disease in this country in 1996. Epidemiologic studies have suggested that Western diets containing high fat, high protein, and low calcium contents are associated with increased incidence of pancreatic cancer. PURPOSE: We investigated whether a Western-style diet containing increased fat content and decreased calcium and vitamin D contents would induce epithelial cell hyperproliferation (excess cell duplication) or hyperplasia (excess cell accumulation) in the pancreas, as was previously demonstrated in the colon and mammary gland. METHODS: C57BL/6J mice at 4 weeks of age were randomly assigned to one of two groups of 14 mice each. One group received the control diet ad libitum, and the other group was given the Western-style diet ad libitum. After 6, 9, and 15 weeks on the diet, four or five mice per group were infused with 5-bromo-2'-deoxyuridine (BrdU) for 72 hours by use of subcutaneously implanted Alzet osmotic pumps. The mice were then killed, and the pancreas of each mouse was removed. In the exocrine pancreas with ductal secretion, the duct system (including interlobular and intralobular ducts and centroacinar [i.e., centroductular] cells) and acini were measured both histopathologically and immunohistochemically (BrdU) and were analyzed without knowledge of the source of the specimens. Two-way analysis of variance was carried out. All P values were generated from two-sided tests for statistical significance. RESULTS: The number of pancreatic ducts (interlobular, intralobular, and centro-acinar-cancer-prone regions in certain rodent models and in humans) and acini per mouse in the Western-style diet group was similar to that in the control diet group during the entire feeding period (P = .76, .32, .93, and .42, respectively). Statistically significant higher BrdU-labeling indices of the ductal interlobular and intralobular epithelial cells were seen in mice fed the Western-style diet than in mice fed the control diet during the entire observation period (P = .014 and .016, respectively). There was no statistically significant difference (P = .098) between both diet groups in the BrdU-labeling indices of the centroacinar epithelial cells. CONCLUSIONS: A Western-style diet induced pancreatic epithelial cell hyperproliferation in mice, further suggesting that increased fat content and decreased calcium and vitamin D contribute to the development of pancreatic neoplasms. 相似文献
103.
用有效质量理论研究了δ掺杂势中电子和空穴的行为。发现能量接近于δ势垒峰的空穴穿越势垒时能产生一系列谐振态。这些状态中的空穴波函数汇聚在势垒峰周围而同量子限制在势阱中的电子波函数交叠,产生光跃迁。用MBE生长的δ掺杂样品进行光调制光谱测量,发现明显的带间跃迁峰。测得的光谱峰同理论计算的能级相吻合,证实了δ势垒中空穴的新行为。 相似文献
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地震勘探震源药柱技术进展 总被引:2,自引:2,他引:0
介绍国内外震源药柱产品现状,着重介绍了湖北凯龙化工集团股份有限公司近期所取得的技术进展,探讨了一些施工设想及地震勘探震源药柱今后可能的发展方向. 相似文献
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本文主要介绍了硅中硼离子注入校准样品的制备与研究。分别用三台SIMS仪器对样品进行了深度剖析与比对,并对用作校准目的的样品主要参数进行了定值。 相似文献
110.
Radiation of an electric dipole located along an arbitrary direction in the presence of a chiral slab is formulated using matrix analysis in conjunction with Fourier transform techniques. Moreover, dyadic Green's function of such a structure may be determined for further investigation porpose. 相似文献