丹酚酸B对高糖日粮小鼠消化系统自由基水平的影响

本文研究了丹酚酸B(salvianolic acid B,Sal B)对灌注及长期摄食高糖小鼠活性氧自由基(reactive oxygen species,ROS)的影响.结果表明:灌胃高糖使小鼠全血ROS于1.5 h达到最大值,灌胃葡萄糖的ROS释放量显著高于蔗糖(P＜0.05);灌胃高糖使小鼠血糖浓度于0.5 h达到最高,灌胃葡萄糖的小鼠血糖浓度有高于灌胃蔗糖的小鼠血糖浓度的趋势(P＞0.05);添加Sal B后并没有改变灌胃高糖小鼠的全血ROS释放和血糖浓度变化趋势,但有降低血糖趋势(P＞0.05),显著减少了ROS的释放量(P＜0.05);添加Sal B后显著降低长期高糖膳食小鼠的全血、肝脏、胰腺、胃、十二指肠、空肠和回肠的ROS释放量.     

Individual and age differences in the feeding ecology of Oystercatchers Haematopus ostralegus wintering on the Exe Estuary, Devon

The habitats and foods used by a sample of marked individuals and by the whole population of Oystercatchers Haematopus ostralegus wintering on the Exe estuary, South Devon, are described. In the spring and early summer, only a few hundred immatures were present. Two thousand adults and several hundred juveniles arrived in late summer from the breeding grounds and remained until the following spring. The majority of the birds were then adults. At low water, most adults fed on the mussel Mytilus edulis beds and ate mussels. Most individuals specialised on this prey and ate little else. Some adults fed on mud-flats and sandflats within the estuary and along the coast, and specialised on a mixture of Nereis diversicolor and Scrobicularia plana or on Cerastoderma edule or Littorina spp. Though some juveniles ate mussels from the time they arrived, most did not. In winter, they took Scrobicularia on mudflats, earthworms Lumbricidae and leatherjackets Tipulidae larvae in fields and Spisula and mussels along the coast. At other times of year they mainly ate Nereis. However, as they grew older, more birds began to specialise on mussels, especially in their second, third and fourth summers when the adults were away. At high water, most birds roosted at the mouth of the estuary or along the coast. However, several hundred fed in the fields in winter with more doing so late in the winter on warm days on Neap tides when less time was available for feeding on the estuary in daylight. Birds feeding on Nereis and Scrobicularia at low water were most often seen in the fields, irrespective of age. Birds feeding on Mytilus and Littorina occurred there rarely, but no bird eating Cerastoderma was seen there. The findings are discussed in relation to age differences in feeding skills and ability to compete successfully with other birds.     

Basipetal Gradient of Axillary Bud Inhibition Along a Rose (Rosa hybridaL.) Stem: Growth Potential of Primary Buds and their Two Most Basal Secondary Buds as Affected by Position and Age

InRosa hybridaL. cv. Ruidriko ‘Vivaldi’®, theeffect of position on growth and development potentials of axillarybuds was investigated by single internode cuttings excised alongthe floral stem and its bearing shoot. The experiments werecarried out in both glasshouses and in a phytotron. The studyfirstly concerned the development of the primary shoot fromthe onset of bud growth until anthesis. The primary shoot wasthen bent horizontally to promote the growth of the two mostproximal secondary buds, the collateral buds, already differentiatedinside the primary bud. They gave rise to basal shoots. In thebasipetal direction, the axillary buds along the floral stemexhibited both an increase in the lag time before bud growthand a decrease in bud growth percentage, demonstrating the existenceof a physiological basipetal gradient of inhibition intrinsicto the buds or due to short range correlations. The same basipetalgradient of inhibition was observed along the floral stem andits bearing shoot, demonstrating that the age of the bud wasnot a major factor in determining the rate of bud growth. Afterbending the primary shoot, the percentage of collateral budgrowth was also affected by the cutting position. The more proximalthe cutting, the lower the sprouting ability of collateral buds.The growth potential of these buds appeared to be already determinedinside the main bud before cutting excision.Copyright 1998 Annalsof Botany Company Axillary bud; basal shoot; cutting; development; endodormancy; growth; paradormancy; position; primary shoot;Rosa hybridaL.; rose; secondary bud; topophysis.     

Sperm storage and degradation in the spermathecae of the salamander Eurycea Cirrigera

Spermathecae are exocrine glands in the roof of the female cloaca that store sperm. Cytological and histochemical data indicate that the one type of secretion into the lumen is a glycoprotein. After a period of stasis in the summer, production of the secretion is initiated in the fall, coincident with an increase in ovarian follicular size. By the time of maximal follicular development and most intense mating activity in March and April, the spermathecal epithelium is filled with secretory granules. The secretory material is released into the lumen, enveloping the sperm. Many sperm remain in the spermathecae after oviposition, and most of these sperm are degraded in the spermathecal epithelium or pass through interruptions in the spermathecal walls caused by desquamation. Sperm in contact with the stromal environment are phagocytized by leukocytes. Some sperm, however, may survive in the lumen until at least the following fall. These sperm retain normal cytology, but whether or not they remain fertile and intact until a subsequent ovipository cycle is unknown.     

探究式课程设计在医学生临床决策能力培养中的探索

临床决策能力是一个医生的必备能力之一，是医学教育中必要且重要的培养目标之一。目前对医学生临床决策能力的培养没有形成完备的体系，一般安排在高年级阶段进行，为时较晚。如何把临床决策能力的培养融入低年级基础课中，以尽早开展能力训练值得探索研究。本研究以医学遗传学课程为例，结合探究式教学方式的特点，模拟临床决策思维过程的各细分模块，优化了课程设计，探索在低年级课程中融入临床决策能力的培养。结果提示：探究式课程设计能充分调动学生主动性，增加学生分析、思考的投入；在教师引导下，促使学生依循临床决策思维的过程得到有效地训练。最后，整理分析了探究式课程设计及实践的思路，总结了设计原则和要点，反思了教学中的经验得失。