护理硕士研究生学习风格的调查研究

[目的]了解护理硕士研究生学习风格,以期为护理教育提供参考,提高教学质量.[方法]采用柯勃编制的学习风格量表对4所大学护理硕士研究生进行问卷调查,并用SPSS13.0统计软件包统计分析.[结果]护理硕士研究生学习风格处于不平衡状态,主要表现在主动实践阶段,其均分落在20%的区间;不同地区学习风格4个阶段得分差异无统计学意义;不同年级间学习风格在具体经验阶段差异有统计学意义(F=3.79,P=0.027),并且随着年级的增长而提高;其他3个环节在不同年级间差异无统计学意义.[结论]护理教学中,要注意引导学生平衡自己的学习风格,特别要加强实践能力和与人合作能力的培养,同时要强化信息教学信念,以拓展学生获取和加工信息的渠道,从而培养和提高学生荻取和加工信息的能力,适应信息社会对人才的需求.     

Control of APC/C-dependent ubiquitin chain elongation by reversible phosphorylation

Most metazoan E3 ligases contain a signature RING domain that promotes the transfer of ubiquitin from the active site of E2 conjugating enzymes to lysine residues in substrates. Although these RING-E3s depend on E2 enzymes for catalysis, how they turn on their E2s at the right time and place remains poorly understood. Here we report a phosphorylation-dependent mechanism that ensures timely activation of the E2 Ube2S by its RING-E3, the anaphase-promoting complex (APC/C); while phosphorylation of a specific serine residue in the APC/C coactivator Cdc20 prevents delivery of Ube2S to the APC/C, removal of this mark by PP2A^B56 allows Ube2S to bind the APC/C and catalyze ubiquitin chain elongation. PP2A^B56 also stabilizes kinetochore–microtubule attachments to shut off the spindle checkpoint, suggesting that cells regulate the E2–E3 interplay to coordinate ubiquitination with critical events during cell division.By promoting the ubiquitination and proteasomal degradation of anaphase inhibitors, the anaphase-promoting complex (APC/C) triggers sister chromatid separation and mitotic exit (1–5). The APC/C also targets kinases and microtubule-binding proteins that ensure accurate assembly of the mitotic spindle. Misregulation of the APC/C has dramatic consequences for cell cycle control; whereas APC/C inhibition causes mitotic arrest and cell death, its untimely activation results in aneuploidy, a common feature of human cancer cells (6).As a RING-dependent E3 ligase, the APC/C stimulates the transfer of ubiquitin from the catalytic cysteine of E2 conjugating enzymes to lysine residues in substrates. In most cases, the APC/C initiates chain formation by using a specific E2, Ube2C (7–10). Once the first ubiquitin molecules have been attached to substrates, another conserved E2, Ube2S, extends K11-linked chains that are recognized by the proteasome for degradation (11–16). Ube2S frequently acts on short chains rather than on single ubiquitin subunits, thereby producing branched conjugates that impart high affinity for proteasomal receptors (13). Consistent with an important role in cell division, activation of Ube2S during mitosis results in a dramatic increase in the abundance of K11 linkages (17, 18), a chain topology required for APC/C-dependent substrate degradation (19).As with many key cell cycle regulators, the APC/C and Ube2S need to be under tight control, and overexpression of Ube2S can promote tumor growth and metastasis in mice (20). The correct timing of APC/C activation is ensured by the spindle checkpoint, a signaling cascade turned on by kinetochores that have not achieved bipolar attachment to the spindle (4, 21, 22). Spindle checkpoint signaling leads to formation of the mitotic checkpoint complex (MCC), composed of Mad2, BubR1, Bub3, and Cdc20. When bound to the APC/C, the MCC competes for recognition of substrate KEN boxes and puts the APC/C coactivator Cdc20 in a position where it is unable to engage another degron, the D box (23–25). In contrast, the MCC does not occupy the binding sites for APC/C E2s or impede the ability of the APC/C to stimulate ubiquitin transfer by Ube2S (12). Thus, although overexpression of Ube2S has been associated with tumorigenesis, the mechanisms that restrict its activity during mitosis have remained elusive.RING-E3s, such as the APC/C, engage their E2 enzymes in a dynamic manner (26). On binding a charged E2, the RING domain stabilizes a closed conformation between the E2 and its donor ubiquitin (14, 27–30). Once this ubiquitin is transferred to a target lysine, the E2 dissociates from the RING domain to allow for its recharging by the E1 (31). For most RING-E3s, the cycles of E2 engagement and dissociation are thought to occur constitutively (32), and only a few examples of controlled E2 activation are known. Access of Cdc34 to its specific RING-E3, the Skp1-Cul1-F box (SCF) complex, can be regulated by phosphorylation or competition with the inhibitory protein glomulin (33, 34). Reminiscent of this situation, Ube2S interacts with the APC/C in a cell cycle-dependent manner, and depletion of Cdc20 prevents Ube2S from stably binding to the APC/C in cells (12, 15). However, as part of the MCC, Cdc20 already associates with the APC/C during prometaphase, when APC/C activity must be low to allow sufficient time for chromosome alignment. How the ability of Ube2S to build ubiquitin chains is restricted during early stages of mitosis to safeguard cells against premature APC/C activation remains unknown.In this study, we identified a mechanism that establishes how the RING-E3 APC/C activates Ube2S at the right time and place. In early mitosis, phosphorylation of a specific serine residue in the APC/C coactivator Cdc20 prevents the stable association of Ube2S with Cdc20 and the APC/C. Conversely, removal of the inhibitory mark on Cdc20 by the phosphatase PP2A^B56 allows Ube2S to engage the APC/C and catalyze ubiquitin chain elongation. PP2A^B56 also stabilizes the kinetochore–microtubule interface to silence the spindle checkpoint (35, 36), suggesting that cells regulate the interplay between RING-E3s and their E2s to coordinate ubiquitination with important events in cell division.     

肝细胞癌门静脉癌栓相关血清小分子量蛋白质标志物的筛选

目的筛选肝细胞癌门静脉癌栓相关的血清小分子量蛋白质标志物。方法收集健康志愿者、肝细胞癌无癌栓患者和肝细胞癌门静脉癌栓患者3组血清各l2份，用16％SDS-PAGE进行双向电泳，得到3组血清小分子量蛋白质表达图谱；经Image Master软件比对分析后，用基质辅助激光解析飞行时间质谱对差异点进行鉴定。结果在16％SDS-PAGE凝胶中，3×10^3～20×10^3区域内蛋白质条带间距较12．5％SDS-PAGE明显增宽，条带数目明显增多，且3组血清小分子量蛋白质表达图谱中均可清晰显示〈20×10^3的小分子量蛋白质斑点。组间比较显示，3组血清共有15个小分子量差异蛋白质点，经鉴定为5种蛋白质。与健康组比较，无癌栓组中载脂蛋白A-I、脂蛋白CⅢ、转甲状腺素蛋白和DNA拓扑异构酶Ⅱ表达降低，而结合珠蛋白-2表达增高；门静脉癌栓组5种蛋白质表达均较无癌栓组降低。结论在肝细胞癌的发生和发展过程中，血清小分子量蛋白质表达谱发生明显变化，差异表达的小分子量蛋白质有可能为肝细胞癌和门静脉癌栓早期预测及治疗监测提供参考。     

Vapor condensation with daytime radiative cooling

A radiative vapor condenser sheds heat in the form of infrared radiation and cools itself to below the ambient air temperature to produce liquid water from vapor. This effect has been known for centuries, and is exploited by some insects to survive in dry deserts. Humans have also been using radiative condensation for dew collection. However, all existing radiative vapor condensers must operate during the nighttime. Here, we develop daytime radiative condensers that continue to operate 24 h a day. These daytime radiative condensers can produce water from vapor under direct sunlight, without active consumption of energy. Combined with traditional passive cooling via convection and conduction, radiative cooling can substantially increase the performance of passive vapor condensation, which can be used for passive water extraction and purification technologies.

Energy and clean water are global challenges that are intertwined in an unfavorable way: even in areas where water is abundant, energy may not be available to purify it for human use (1, 2). There has been strong interest in developing passive technologies to purify or harvest water without using fuel or electricity. In this context, passive vapor condensation becomes particularly important because many passive water technologies go through the vapor phase of water in their harvesting or purification processes.Traditional vapor condensation technique is based on convective and conductive heat exchange with ambient environments. This technique is widely used in systems with hot vapors (3–6). However, with ever-increasing emphasis on passive systems, there are many situations in which warm- or even room-temperature vapor needs to be effectively condensed, such as extracting water from atmosphere (7–9) and warm vapor generated from high-efficiency solar evaporation (10). For vapor at such temperatures, most traditional condensers fail. For this reason, there is a clear need for a condensation technique to complement traditional condensers.A different technique is based on radiative vapor condensation. Darkling beetles in the Namib desert (11) use this technique to collect water. Their bodies function as a cooling surface by shedding thermal energy through midinfrared (mid-IR) radiation toward a clear nighttime sky, generating dew from humid air. This mechanism is also used by commercial radiative dew condensers (7–9). However, neither Namib beetle nor existing dew condensers can operate in the daytime (7). Those nighttime radiative condensers are incompatible with many emerging water technologies that require 24 h operation or direct access to sunlight.Recently, Fan et al. showed that passive radiative cooling to subambient temperatures can be realized even during the daytime, by integrating a high-efficiency solar reflector with a high-emissivity thermal emitter in the mid-IR atmospheric transparency window (12). Using this work as a basis, here we demonstrate a daytime radiative condenser. Compared to existing radiative vapor condensers (7–9), our condenser can function even in the presence of sunlight, which is essential for integration into passive water-harvesting systems that mainly operate during daytime.     

三基因突变小鼠血脂代谢及动脉粥样硬化早期病变特征

目的研究血脂代谢相关基因与瘦素受体基因联合突变导致小鼠血脂代谢紊乱的发生机制和动脉粥样硬化早期病变的特点及两者间的关系。方法应用生物化学及组织形态学手段对三基因突变(apoE-/-/LDLR-/-/Leprdb/db)与双基因突变(apoE-/-/LDLR-/-)小鼠和单基因突变(Leprdb/db)小鼠之间血脂及动脉粥样硬化早期病变的差异进行了比较研究。结果三基因突变小鼠3周龄时血浆总胆固醇、甘油三酯和血糖浓度分别为(1988±190)、(293±029)和(727±088)mmol/L,均高于双基因和单基因突变小鼠,同时出现轻微的主动脉内膜损伤,血脂及动脉粥样硬化程度随年龄增长而加重。11周龄三基因突变小鼠血浆总胆固醇、甘油三酯和血糖水平分别高出双基因突变小鼠166、141和24倍,且动脉内膜病变较双基因和单基因突变小鼠明显,其严重程度与血脂紊乱正相关。结论三个脂代谢相关基因联合突变在导致小鼠血脂代谢紊乱及主动脉粥样硬化病变的发生发展中起重要作用。     

冠状动脉内支架置入术在冠心病治疗中的价值

目的 评价冠状动脉内支架置入术在冠心病治疗中的临床应用价值。方法 对157例206支冠状动脉病变内置入203只支架，其中置入左前降支103只，右冠状动脉57只，左回旋支42只，左主干1只。结果 157例全部置入成功。置入后经冠状动脉造影证实狭窄消失，效果良好。其中5例急性心肌梗死患者由于急诊置入支架后，病情迅速缓解。择期冠状动脉支架置入术全部置入成功，无一例发生严重并发症。结论 冠状动脉内支架置入术是治疗冠心病的一种安全可靠、效果良好的介入性治疗方法、有良好的应用价值。     

Effects of administration styles of arsenic trioxide on intracellular arsenic concentration, cell differentiation and apoptosis

We studied the effects of varying and steady-state concentrations of arsenic trioxide (As2O3) on apoptosis and differentiation of several cell lines in vitro. We also studied the same effects of fluctuating vs constant concentrations of As2O3 in vivo in patients treated with daily 3-hour fast infusions or daily slow, continuous infusions. Intracellular concentrations of arsenic and apoptosis rate were higher whereas differentiation was reduced in cells exposed to constant concentrations of As2O3.