Basic concepts of fluid responsiveness

Predicting fluid responsiveness, the response of stroke volume to fluid loading, is a relatively novel concept that aims to optimise circulation, and as such organ perfusion, while avoiding futile and potentially deleterious fluid administrations in critically ill patients. Dynamic parameters have shown to be superior in predicting the response to fluid loading compared with static cardiac filling pressures. However, in routine clinical practice the conditions necessary for dynamic parameters to predict fluid responsiveness are frequently not met. Passive leg raising as a means to alter biventricular preload in combination with subsequent measurement of the change in stroke volume can provide a fast and accurate way to guide fluid management in a broad population of critically ill patients.     

Stem cells: Insights into the secretome

Stem cells have been considered as possible therapeutic vehicles for different health related problems such as cardiovascular and neurodegenerative diseases and cancer. Secreted molecules are key mediators in cell–cell interactions and influence the cross talk with the surrounding tissues. There is strong evidence supporting that crucial cellular functions such as proliferation, differentiation, communication and migration are strictly regulated from the cell secretome. The investigation of stem cell secretome is accumulating continuously increasing interest given the potential use of these cells in regenerative medicine. The scope of the review is to report the main findings from the investigation of stem cell secretome by the use of contemporary proteomics methods and discuss the current status of research in the field. This article is part of a Special Issue entitled: An Updated Secretome.     

Estimation of Free Energy Systematic Errors in Molecular Simulations of Globular Proteins Surrounded by Finite Water Clusters. One Center Multipole Expansion of Reaction Field Differences

Free energy calculated in simulations on the atomic level (Monte Carlo or Molecular Dynamics) has a systematic error, if the water shell surrounding a globular protein is finite. The error (“cluster error”) is equal to a difference of free energies obtained in simulations with an infinite and finite water shell. In this work a continuum dielectric model was used to estimate the “cluster error”. A multipole expansion of the estimate was performed for a water shell with a spherical outer boundary. The expansion has very simple form. Each term is a product of two functions, one of them depending only on the charge's conformation, and the other one only on dielectric properties of the system. There are two practical uses of the expansion. First, it may be used to estimate the “cluster error” in a simulation already made; second, it may be used to plan a simulation in such a way that the “cluster error” is minimal. Numerical values of the largest terms in the multipole expansion corresponding to a typical system in simulations of globular proteins are given.     

CIRCADIAN PATTERN OF AMBULATORY BLOOD PRESSURE IN UNTREATED HYPERTENSIVE PATIENTS WITH AND WITHOUT METABOLIC SYNDROME

There is a strong association between metabolic syndrome (MS) and increased risk of end-organ damage, cardiovascular disease, stroke, and cardiovascular mortality. Moreover, non-dipping (<?10% decline in the asleep relative to the awake blood pressure [BP] mean) and elevated ambulatory pulse pressure (PP), among other factors related to the circadian BP pattern, have also been associated with increased cardiovascular morbidity and mortality. This cross-sectional study investigated the circadian BP pattern in 2,045 non-diabetic untreated patients with uncomplicated essential hypertension (941 men/1,099 women), 48.7?±?11.9 yrs of age, classified by the presence or absence of MS. BP was measured by ambulatory monitoring for 48 consecutive hours to substantiate reproducibility of the dipping pattern. Physical activity was simultaneously monitored every min by wrist actigraphy to accurately calculate mean BP when awake and asleep for each subject. MS was present in 40.7% of the patients. Patients with MS were characterized by a significantly higher 24?h mean of systolic BP and a lower diastolic BP compared to patients without MS. Accordingly, ambulatory PP was significantly elevated the entire 24?h in MS patients. The prevalence of an altered non-dipper BP profile was significantly higher in MS patients (48.4 vs. 36.1% in patients without MS, p?<?0.001). MS patients were characterized, among other risk factors, by significantly higher uric acid, fibrinogen, leukocyte count, hemoglobin and globular sedimentation velocity, plus lower estimated glomerular filtration rate. Apart from corroborating the significant increased prevalence of a blunted nocturnal BP decline in MS, this study documents ambulatory PP is higher in MS, without differences between groups in mean arterial pressure. This elevated PP might reflect increased arterial stiffness in MS. MS patients were also characterized by elevated values of relevant markers of cardiovascular risk, including fibrinogen and globular sedimentation velocity. These collective findings indicate that MS should be included among the clinical situations in which ambulatory BP monitoring is recommended. (Author correspondence: rhermida@uvigo.es)     

Analytical methods for detecting pesticide switches with evolution of pesticide resistance

After a pest develops resistance to a pesticide, switching between different unrelated pesticides is a common management option, but this raises the following questions: (1) What is the optimal frequency of pesticide use? (2) How do the frequencies of pesticide applications affect the evolution of pesticide resistance? (3) How can the time when the pest population reaches the economic injury level (EIL) be estimated and (4) how can the most efficient frequency of pesticide applications be determined? To address these questions, we have developed a novel pest population growth model incorporating the evolution of pesticide resistance and pulse spraying of pesticides. Moreover, three pesticide switching methods, threshold condition-guided, density-guided and EIL-guided, are modelled, to determine the best choice under different conditions with the overall aim of eradicating the pest or maintaining its population density below the EIL. Furthermore, the pest control outcomes based on those three pesticide switching methods are discussed. Our results suggest that either the density-guided or EIL-guided method is the optimal pesticide switching strategy, depending on the frequency (or period) of pesticide applications.     

Determination of Trace Element Stability in Sediments Using Redox Gel Probes: Probe Construction and Theoretical Performance

A simple and inexpensive technique is described that can be used to assess the stability of redox-sensitive compounds in the sediments of wetlands and other shallow water environments. In this method, solid redox-sensitive compounds, such as manganese dioxide (MnO 2 ), are incorporated into agar gels held in rigid plastic holders. One surface of the gel remains exposed along the length of the resulting probe. The probes are pushed vertically into sediments and are left in situ for a period of time (days to weeks), after which they are visually inspected and chemically analyzed. The diffusion of nonreactive solutes (e.g., sulfate) in 2% (wt/vol) agar was unaffected by the presence of immobilized MnO 2 particles. The rate of dissolution of particulate MnO 2 in agar gels in the presence of an external diffusing reductant (L-ascorbic acid) could be quantified by digital analysis of pixel density on gel images. Redox gel probes incubated in the sediment of a wetland built to remove manganese from circumneutral pH coal mine drainage demonstrated different patterns of depth-dependent MnO 2 stability along a 15-m transect. MnO 2 gel probe results were consistent with data obtained using sediment cores and porewater diffusion samplers.     

Molecular weight distribution and functional group profiles of TEMPO-oxidized lyocell fibers

The effects of TEMPO-mediated oxidation, performed with NaClO, a catalytic amount of NaBr, and 2,2′,6,6′-tetramethylpiperidine-1-oxy radical (TEMPO), were studied on lyocell fibers by means of GPC using multiple detection and group-selective fluorescence labeling according to the CCOA and FDAM methodology. The applied method determines functional group content as a sum parameter, as well as functional group profiles in relation to the molecular weight of the cellulose fibers. Both the CHO and COOH profiles, as well as molecular weight alterations, were analyzed. A significant decrease in the average molecular weight was obtained during the first hour of TEMPO-mediated oxidation, but prolonged oxidation time resulted in no strong additional chain scission. Significant amounts of COOH groups were introduced in the high molecular weight fractions by the oxidation with higher concentrations of NaClO (2.42–9.67 mmol NaClO/g fiber) after modification times of 1 h or longer.     

不同电针方法对慢性应激抑郁模型大鼠下丘脑TRH表达的影响

目的:研究分析两种不同电针方法对慢性应激抑郁模型大鼠(CUMS)下丘脑中促甲状腺激素释放激素(TRH)表达的影响。方法:选取60只健康雄性SPF级SD大鼠编号后采用随机数字表法分为对照组(正常喂养)、模型组(仅建立CUMS模型,不予治疗)、观察组A(建立CUMS模型后,脉冲电针治疗)、观察组B(建立CUMS模型后,音乐电针治疗)、氟西汀组(建立CUMS模型后,氟西汀治疗)各12只,对除对照组之外的其他各组大鼠进行1只/笼的孤养结合方式建造CUMS模型,利用开野实验观察各组大鼠行为学改变,采用实时荧光定量(PCR)法测定各组大鼠下丘脑组织中TRH m RNA的表达,采用免疫组化法测定TRH蛋白的表达。结果:在刺激21 d后,模型组大鼠的水平运动次数、垂直运动次数显著的低于对照组、实验组A、实验组B、氟西汀组,且差异均具有统计学意义(P0.05),实验组A、实验组B、氟西汀组大鼠的水平运动次数、垂直运动次数显著低于对照组,且差异均具有统计学意义(P0.05),实验组A、实验组B、氟西汀组大鼠的水平运动次数、垂直运动次数差异无统计学意义(P0.05);模型组大鼠的下丘脑TRH m RNA、TRH蛋白水平低于对照组、实验组A、实验组B、氟西汀组,且差异均具有统计学意义(P0.05),实验组A、实验组B、氟西汀组大鼠的大鼠的下丘脑TRH m RNA、TRH蛋白水平显著低于对照组,且差异均具有统计学意义(P0.05);实验组A、实验组B、氟西汀组大鼠的大鼠的下丘脑TRH m RNA、TRH蛋白水平差异无统计学意义(P0.05)。结论:CUMS大鼠下丘脑中促甲状腺激素释放激素表达水平降低,脉冲电针与音乐电针能有效逆转这一现象,效果相当。     

高山姬鼠下丘脑神经肽表达量的季节性变化

为阐明高山姬鼠(Apodemus chevrieri)下丘脑神经肽表达量在季节性变化条件下对其体重调节的作用,测定了不同季节高山姬鼠的体重、体脂含量、食物摄入量以及血清瘦素浓度和神经肽Y(NPY)、刺鼠相关蛋白(Ag RP)、阿片促黑色素原(POMC)和可卡因-安他非明转录调节肽(CART)表达量。采用食物平衡法测定高山姬鼠的食物摄入量,体脂含量用索氏抽提法进行测定,采用实时荧光PCR仪测定下丘脑神经肽表达量。采用单因素方差分析或协方差分析进行检验,相关性采用Pearson相关分析。高山姬鼠的体重和体脂均出现了季节性变化,冬季较低,夏季较高。食物摄入量季节性差异显著,冬季较高,夏季最低。血清瘦素含量也出现了季节性变化,与体脂变化趋势类似,瘦素含量与脂肪含量呈正相关关系。下丘脑神经肽NPY、Ag RP、POMC和CART表达量季节性差异显著。食物摄入量与NPY和Ag RP负相关,与POMC和CART正相关。以上结果表明,高山姬鼠在季节性变化过程中冬季降低体重、体脂,增加摄入量来维持生存。瘦素通过作用于下丘脑神经肽基因来调节高山姬鼠的体重平衡。     

Production,application, and field performance of Abietiv™, the balsam fir sawfly nucleopolyhedrovirus

Beginning in the early 1990s, the balsam fir sawfly (Neodiprion abietis) became a significant defoliating insect of precommercially thinned balsam fir (Abies balsamea (L.) Mill.) stands in western Newfoundland, Canada. In 1997, a nucleopolyhedrovirus (NeabNPV) was isolated from the balsam fir sawfly and, as no control measures were then available, NeabNPV was developed for the biological control of balsam fir sawfly. In order to register NeabNPV for operational use under the Canadian Pest Control Products Act, research was carried out in a number of areas including NeabNPV field efficacy, non-target organism toxicology, balsam fir sawfly ecology and impact on balsam fir trees, and NeabNPV genome sequencing and analysis. As part of the field efficacy trials, approximately 22 500 hectares of balsam fir sawfly-infested forest were aerially treated with NeabNPV between 2000 and 2005. NeabNPV was found to be safe, efficacious, and economical for the suppression of balsam fir sawfly outbreak populations. Conditional registration for the NeabNPV-based product, Abietiv™, was received from the Pest Management Regulatory Agency (Health Canada) in April 2006. In July 2006, Abietiv was applied by spray airplanes to 15 000 ha of balsam fir sawfly-infested forest in western Newfoundland in an operational control program.