Direct observation of toxic effects of cyanobacterial extracellular products on Daphnia

The filtrate from a suspension of the cyanobacterium Anabaena minutissima var. attenuata depressed thoracic limb beat frequency of Daphnia carinata by 38–45% in a food-free medium. Repeated exposure to the filtrate produced a similar depression of activity with full or neary full recovery. Response time to the filtrate was 5–8 min and recovery time was 8–12 min. The dose effect on limb beat frequency was continuous, linear, correlated with increased concentration and with no threshold. There was no relationship between body length and limb beat frequency.The interaction between toxicity and food concentration was tested using the diatom Cyclotella suspended in Anabaena filtrate. Daphnia limb beat frequency was depressed by 62%.     

Atrial fibrillation after thoracic surgery for lung cancer: use of a single cut-off value of N-terminal pro-B type natriuretic peptide to identify patients at risk

Postoperative atrial fibrillation (AF) is a well-known complication occurring after thoracic surgery. B-type natriuretic peptide has recently been investigated as a predictive marker of postoperative AF after cardiac surgery. The aim of this study was to evaluate a definite cut-off for N-terminal pro-B type natriuretic peptide (NT-proBNP) in predicting postoperative AF in lung cancer patients. NT-proBNP was determined before and after surgery in 400 patients. Cardiac function was monitored by continuous postoperative ECG and clinical cardiological evaluation. AF occurred in 18% of the patients. Receiver operating characteristic curve analyses identified a cut-off of 182.3?ng l^?1 as the one with the highest sensitivity and specificity. Perioperative increased levels of NT-proBNP seem to predict postoperative AF in patients undergoing thoracic surgery, and a single cut-off of 182.3?ng l^?1 can be used to select high-risk patients who could receive preventive therapy, leading to a considerable decrease in the total costs associated with the management of this complication.     

Solution NMR views of dynamical ordering of biomacromolecules

Background

To understand the mechanisms related to the ‘dynamical ordering’ of macromolecules and biological systems, it is crucial to monitor, in detail, molecular interactions and their dynamics across multiple timescales. Solution nuclear magnetic resonance (NMR) spectroscopy is an ideal tool that can investigate biophysical events at the atomic level, in near-physiological buffer solutions, or even inside cells.

Thermoregulation and flying habits of the Japanese sulfur butterfly Colias erate (Lepidoptera: Pieridae) in an open habitat

This study evaluated the impact of the thermal environment on the flying behavior of male Japanese sulfur butterflies Colias erate searching for females in an open habitat. Thoracic temperature was monitored before and after flight. Mean thoracic temperature of butterflies immediately after landing was consistently higher than, but independent of, ambient temperature. Although ground speed of flying butterflies was different between flight types, air speed against the butterfly was similar across flight types. The excess of thoracic over ambient temperature was lower in flying butterflies than in basking ones, as predicted by a model. This difference appeared to be due to air current, which enhanced heat loss. In a laboratory study, newly eclosed male butterflies were placed under an incandescent lamp to measure their thoracic temperature at different air current speeds. The excess of thoracic over ambient temperature decreased as the speed of air currents increased. When the air current was similar to the air speed against flying butterflies in the field, a substantial decrease occurred in the operative thoracic temperature.     

江豚脊髓的研究

本文研究了江豚脊髓的形态和内部构造,首次报道鲸类脊髓灰质分层和神经核的对应关系,并发现在胸段8—13节 、腰尾段1一6节等白质的侧索中有特殊细胞群,以多极或小三角形细胞为多,也有少数棱形细胞,呈串珠状排列或散在分布,分别与背角I- Ⅴ层相联系,它们显示出与感觉传导系有关,作者认为应分别称之为胸外侧核和腰尾外倒核。     

HTEA对全脑缺血/再灌注大鼠脑血流及海马细胞凋亡的影响

目的:研究上胸段硬膜外阻滞(high thoracic epidural anesthesia,HTEA)对大鼠全脑缺血再灌注损伤(global cerebral ischemia,GCI)再灌注期间脑血流及凋亡相关蛋白Bcl-2和Bax的影响。方法:本研究选用成年雄性Wistar大鼠成功进行T4-5间隙硬膜外置管,并建立四血管阻断的全脑缺血模型进行15 min的全脑缺血。根据通过硬膜外导管输注药物不同,随机分为四组:假手术组(Sham,0.9%生理盐水)、假手术-硬膜外组(Sham-HTEA,0.25%布比卡因)、全脑缺血组(GCI,0.9%生理盐水)和硬膜外组(HTEA,0.25%布比卡因)。给药时间从缺血前15 min开始以20μL/h的速度持续输注至再灌注24 h。缺血前至再灌注2 h观察平均动脉压(MAP)和心率(HR),激光多普勒血流仪监测脑血流(cerebral blood flow,CBF),Western-blot检测再灌注24 h海马凋亡蛋白Bcl-2和Bax含量。结果:HTEA组与GCI组相比,缺血期间及再灌注2 h内的MAP和HR无统计学差异,而与Sham组相比,GCI组的MAP缺血时升高,而再灌注时降低(P0.05);再灌注10 min的高灌注期HTEA组CBF明显低于GCI组(123.1%±35.2%vs 177.5%±32.4%,P0.01),再灌注60 min至120 min的低灌注期的大部分时间点HTEA组CBF均高于GCI组(P0.05);再灌注24 h海马组织Bax/Bcl-2比例明显降低(P0.01)。结论:0.25%的布比卡因20μL·h-1连续上胸段硬膜外阻滞可以维持血流动力学稳定,且可改善大鼠全脑缺血再灌注后低灌注期的脑血流量,并减少再灌注24 h海马Bax/Bcl-2比例。     

低能离子束在植物种粒和微生物中的穿透深度

计算了低能离子注入生物体中的穿透深度,考虑生物媒质为匀相多组元系统,求出了平均射程的一般理论公式,将其用于植物种粒和微生物中。以30keV的N 注入水稻种子和100keV的As 注入微生物细胞为例,计算了平均穿透深度,结果与实验资料一致。指出抽真空过程中水分蒸发及离子注入时的热效应和机械效应对植物种子结构的动态影响,可使穿透深度大大加大。     

Psidium guajava Paluma responses to environmental conditions and ozone concentrations in the urban forest of São Paulo,SE-Brazil

Tropospheric ozone concentrations (O₃) are continuously increasing with harmful effects on vegetation. Ozone uptake triggers oxidative stress that may promote adverse changes in various plant physiological processes. The aim of this study was to evaluate the relationship between meteorological conditions and O₃ exposure in foliar injuries, gas exchanges and antioxidant enzyme activity in Psidium guajava Paluma. Saplings of Paluma were exposed in a site contaminated by O_3. Foliar injuries, gas exchanges, and the activity of superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) were evaluated weekly. Results were analyzed by multivariate analysis. The O₃ exposure reduced carbon assimilation and induced the onset of foliar injuries. The enzymatic activities were more related to meteorological conditions than to O₃ exposure, indicating that these enzymes are not this species’ first line of defense. However, our finding indicates that Paluma may be considered a response indicator, given its presentation of foliar injuries even at low O₃ concentrations.