Acclimation of photosynthetic temperature optima of temperate and boreal tree species in response to experimental forest warming

Rising temperatures caused by climate change could negatively alter plant ecosystems if temperatures exceed optimal temperatures for carbon gain. Such changes may threaten temperature‐sensitive species, causing local extinctions and range migrations. This study examined the optimal temperature of net photosynthesis (T_opt) of two boreal and four temperate deciduous tree species grown in the field in northern Minnesota, United States under two contrasting temperature regimes. We hypothesized that T_opt would be higher in temperate than co‐occurring boreal species, with temperate species exhibiting greater plasticity in T_opt, resulting in better acclimation to elevated temperatures. The chamberless experiment, located at two sites in both open and understory conditions, continuously warmed plants and soils during three growing seasons. Results show a modest, but significant shift in T_opt of 1.1 ± 0.21 °C on average for plants subjected to a mean 2.9 ± 0.01 °C warming during midday hours in summer, and shifts with warming were unrelated to species native ranges. The 1.1 °C shift in T_opt with 2.9 °C warming might be interpreted as suggesting limited capacity to shift temperature response functions to better match changes in temperature. However, T_opt of warmed plants was as well‐matched with prior midday temperatures as T_opt of plants in the ambient treatment, and T_opt in both treatments was at a level where realized photosynthesis was within 90–95% of maximum. These results suggest that seedlings of all species were close to optimizing photosynthetic temperature responses, and equally so in both temperature treatments. Our study suggests that temperate and boreal species have considerable capacity to match their photosynthetic temperature response functions to prevailing growing season temperatures that occur today and to those that will likely occur in the coming decades under climate change.     

基于rDNA ITS序列对绒泡菌目黏菌系统发育的探讨

绒泡菌目Physarida是黏菌纲Myxogastria最大的一个目,对其系统发育关系的研究一直是根据形态特征。为了从分子水平探讨绒泡菌目乃至黏菌纲的系统发育关系,以黏菌r DNA ITS通用引物对绒泡菌目5属8种黏菌的r DNA ITS进行扩增和测序,结合Gen Bank中已有的黏菌r DNA ITS序列,利用贝叶斯推断法(Bayesian inference,BI)和最大似然法(Maximum likelihood,ML)构建系统发育树。结果表明:绒泡菌目不同物种的r DNA ITS区在碱基组成和长度上差异明显,长度为777–1 445bp,G+C mol%在53.4%–61.9%之间。绒泡菌目与发网菌目Stemonitida聚类为两个明显的分支,在绒泡菌目分支上,绒泡菌科Physaraceae和钙皮菌科Didymiaceae各聚为一支,支持了形态学上以孢丝是否具有石灰质为依据区分这两个科的观点。由多份不同地理来源的鳞钙皮菌Didymium squamulosum材料组成的钙皮菌科又形成3个分支,证实了这个形态种是由地域来源广泛、繁殖亲和性各异和遗传变异较大的不同生物种组成的复合体。     

二甲双胍抗肿瘤效应的基础与临床研究进展

二甲双胍(Metformin)是一种胰岛素增敏剂,临床上主要用于2型糖尿病的治疗。越来越多的证据表明,二甲双胍能够发挥抗肿瘤效应,它通过活化磷酸腺苷蛋白激酶(AMPK),阻断哺乳动物雷帕霉素靶蛋白(m TOR)信号通路抑制肿瘤细胞的生长,并且参与细胞周期、凋亡、血管新生等多种生物学行为。不仅如此,二甲双胍的抗肿瘤临床研究也不断出现,包括大样本回顾性研究和前瞻性研究。这些研究数据不仅为二甲双胍抗肿瘤效应提供了有益的证据支持,也为二甲双胍及其介导的抗肿瘤分子信号途径的阐明奠定了理论依据。     

“首届中国孤儿药研发论坛”专家观点（续）

对 2015 年 4 月 25 日召开的“首届中国孤儿药研发论坛”与会专家对话内容进行归纳总结,旨在为从事罕见病诊断和孤儿药研发工作的人士提供信息参考。来自产、学、研领域的专家从研发、临床、审评、投资、媒体等角度探讨了中国孤儿药研发策略。     

Physiological status of broiler chicks at pulling time and the relationship to duration of holding period

Newly hatched chicks may be held longer than 48 h and experience long periods of fasting in commercial hatcheries. Limited information is known about the physiological status of chicks in such situations, due to the difficulty of precisely recording time of hatch. This study investigated the effect of the time from hatch to pulling (holding period) on physiological measures/parameters in 109 broiler chicks. Fertile Ross 308 eggs were incubated in a custom built small-scale incubator. The individual hatching time of each focal chick was determined using eggshell temperature monitoring. At ‘pulling’ (512 h of incubation time), the quality of focal chicks was assessed using the chick scoring method and physiological parameters were measured including BW, organ (heart, liver and stomach) weights, blood values and plasma corticosterone level. The time from hatch to pulling varied from 7.58 to 44.97 h. Egg weight at setting was significantly correlated with chick BW and weight of organs at pulling, but had no effect on chick quality, blood values and plasma corticosterone. Relative BW at pulling was negatively associated with the duration of holding period (P=0.002). However, there was a positive correlation between relative stomach weight and the duration of the holding period (P<0.001). As the holding period duration increased, there was a trend that blood partial pressure of oxygen, haematocrit and haemoglobin also increased, and blood partial pressure of carbon dioxide, total carbon dioxide and bicarbonate decreased (P<0.05). A wide range of plasma corticosterone was observed from chicks that had experienced different durations of holding period. We conclude that shortening the hatch window and minimising the number of chicks that experience a long holding period before pulling may improve chick quality and physiological status, which may be due to unfavourable environmental conditions that include feed and water deprivation.     

Intraoperative squash cytology: accuracy and impact on immediate surgical management of central nervous system tumours

N. Krishnani, N. Kumari, S. Behari, C. Rana and P. Gupta
Intraoperative squash cytology: diagnostic accuracy and its impact on immediate surgical management of central nervous system tumours Objective: To assess the diagnostic accuracy of squash cytology, reasons for deferment, disagreement and partial agreement, and assess its impact on immediate surgical management of central nervous system tumours. Study design: All cases of squash cytology received from January 2007 to July 2010 were reviewed and correlated with final histopathological diagnoses. Deferments, disagreements and partial disagreements were reviewed to look for possible reasons. The impact of disagreements and partial agreements on immediate surgical management was evaluated in consultation with neurosurgeons. Results: Overall accuracy (including complete and partial agreement) for squash smear diagnosis of 334 cases was 94.9% while complete agreement was 79.9%, excluding deferred cases. Disagreement was seen in 17 cases and 31 cases were deferred for final histopathology diagnosis. Good correlation was seen in astrocytoma, meningioma, schwannoma, medulloblastoma, pituitary adenoma and metastatic carcinoma, whereas poor correlation was seen in oligodendroglioma, ependymoma and lymphoma. Among 17 cases with disagreement and 50 cases with partial agreement, an adverse impact on immediate surgical management was found in six (35.3%) cases and one (2.0%) case, respectively. The sensitivity and specificity of squash for diagnosis of neoplastic lesions were 98.7% and 87.5%, respectively. Conclusion: Squash cytology is a rapid, reliable, simple technique for intraoperative consultation in neurosurgical practice with high overall accuracy. Causes causing an adverse impact on surgical management were rare and potential avoidable reasons for them were identified.     

转化医学：现代医学发展的动力

Translational medicine is a class of medicalresearch that proposes a two-way interaction betweenlaboratory and clinical research[1].Elias A.Zerhouni,the director of the National Institutes of Health(NIH),     

双因素理论在我院医师临床技能考核中的运用

将临床技能考核作为新的条件引入到专业技术职务评聘中是职称评聘工作的一个创新。要使考核的实施既达到加强医师队伍建设的目的,又不至影响医师工作积极性是实施者必须考虑的关键问题。文章介绍我院运依据“双因素理论”制定实施医师临床技能考核的一系列配套政策,在保障职工利益的同时激励其不断提高技术水平和职业水准,使技能考核在顺利引入的同时又取得明显效果,达到提高医院管理水平、加强医师队伍建设的目的。     

小菜蛾的耐热性

小菜蛾是世界范围内十字花科蔬菜上的重要害虫.临界高温(critical thermal maximum, CTMax)是昆虫耐热性的常用指标.采用动态加热方法,利用自行组装的装置测定了小菜蛾的临界高温,以此作为其耐热性指标,研究发育阶段、饲养温度、世代、性别和热激对小菜蛾耐热性的影响.结果表明： 25 ℃下饲养的小菜蛾4龄幼虫的CTMax 均值为50.31 ℃,显著高于1龄幼虫(43.03 ℃)、2龄幼虫(46.39 ℃)、3龄幼虫(49.67 ℃)以及雌性成虫(45.76 ℃)和雄性成虫(47.73 ℃);不同饲养温度(20、25和30 ℃)下成虫耐热性无显著差异;30 ℃下饲养1代、3代及6代的不同世代成虫CTMax也无显著变化;所有处理雌雄成虫的CTMax无显著差异;40 ℃下45 min热激可使5日龄雄成虫的CTMax值从45.51 ℃增加到46.49 ℃.     

The impact of confounders on the test performance of natriuretic peptides for cardiac dysfunction in subjects aged 80 and older

The hypothesis that natriuretic peptides could be used to identify ‘pancardiac’ damage has been proposed. However, multiple factors are known to influence circulating levels of natriuretic peptides, especially in the very old. Therefore, the impact of confounders on the association between natriuretic peptide levels and cardiac dysfunction was further explored in subjects aged 80 and older. A diagnostic cross-sectional study embedded within the BELFRAIL study (n = 567) was performed. Baseline BNP and NT-proBNP levels were measured and echocardiograms were performed at the subject's home. Cardiac dysfunction was defined as systolic dysfunction, valvular heart disease or isolated severe diastolic dysfunction. Several functional and structural echocardiographic parameters were independently related to circulating levels of natriuretic peptides. Cystatin C, BMI, β blockers, diabetes, heart frequency, usCRP, age and sex were identified as confounders. The prevalence of cardiac dysfunction was 17.1% in the subjects without and 30.8% in the subjects with chronic atrial fibrillation (CAF) or pacemaker (PM). Only in subjects with CAF or PM the C statistic for cardiac dysfunction improved after correcting for confounders. The post-test probability for a negative test (PTP−) ranged from 3.7% to 12.2% and the PTP+ ranged from 21.9% to 62.2% in different strata of confounders. According to these data adjusting for identified confounders does not improve the diagnostic accuracy of the natriuretic peptides for cardiac dysfunction, except in subjects with CAF or PM. Stratifying for individual confounders showed that different cut-off values could be used to optimize the diagnostic characteristics of natriuretic peptides.