Solubility, adsorption, and the thermodynamics of the cutoff effect

For many years, the expression "cutoff effect of anesthesia," has been used to denote the failure of the higher alcohols or paraffins to produce anesthesia. As such, it is used to assess the plausibility of specific models, proposed for anesthesia. However, the uses were shown, in many respects, to be problematic. This article augments the notion of the cutoff to fit for all cases in which only some of the molecules in a homologous series are anesthetics. We find that the location of the cutoff points is affected by three free energy quantities: that of the adsorption of the agent to the anesthetic "site" (f(sl,site)), that of the perturbation of the site (f(ll,site)), and that of the evaporation of the agent from its pure condensed phase (Deltamu degrees (evaporation)). This outcome indicates that the cutoff cannot be attributed to a single parameter. In addition, the analyses that attribute the cutoff to the failure of compounds to obey the much-used Meyer-Overton correlation will have to be amended. This article shows that cutoff results can be used to elucidate the structure of a site.     

Mechanism of pressure-induced thermostabilization of proteins: studies of glutamate dehydrogenases from the hyperthermophile Thermococcus litoralis

In this study, we investigated the effect of pressure on protein structure and stability at high temperature. Thermoinactivation experiments at 5 and 500 atm were performed using the wild-type (WT) enzyme and two single mutants (D167T and T138E) of the glutamate dehydrogenase (GDH) from the hyperthermophile Thermococcus litoralis. All three GDHs were stabilized, although to different degrees, by the application of 500 atm. Interestingly, the degree of pressure stabilization correlated with GDH stability as well as the magnitude of electrostatic repulsion created by residues at positions 138 and 167. Thermoinactivation experiments also were performed in the presence of trehalose. Addition of the sugar stabilized all three GDHs; the degree of sugar-induced thermostabilization followed the same order as pressure stabilization. Previous studies suggested a mechanism whereby the enzyme adopts a more compact and rigid structure and volume fluctuations away from the native state are diminished under pressure. The present results on the three GDHs allowed us to further confirm and refine the proposed mechanism for pressure-induced thermostabilization. In particular, we propose that pressure stabilizes against thermoinactivation by shifting the equilibrium between conformational substates of the GDH hexamer, thus inhibiting irreversible aggregation.     

浸提条件对小麦秸秆中化感物质检测结果的影响

通过对比不同浸提条件下小麦秸秆中化感物质的检测结果,发现浸提温度和时间对化感物质的最终结果有很大的影响,在室温条件下,化感物质的量随着浸提时间的延长而增长,但在50℃时,随着浸提时间的延长,化感物质的量反而降低。化感物质最大量在50℃,24h浸提条件下得到。在高温高压条件下提取到的化感物质的量多于多数条件下得到的量（除少于50℃,24h浸提条件下得到的量）。试验结果表明随着漫提温度升高,植物材料中的化感物质在水中的溶解速度加快,但是性质不稳定,容易分解变性。     

High pressure and glycolytic flux in the freshwater Chinese crab, Eriocheir sinensis

The hexose part of glycolysis has been studied in the freshwater Chinese crab Eriocheir sinensis exposed to high pressure (101 ATA, i.e. 1000 m depth) at 14°C and in normoxic conditions. Glycolytic fluxes (from glucose, J_A and from Glucose 6 Phosphate, J_B) have been determined using NADH depletion during the conversion of dihydroxy acetone phosphate into α-glycerol phosphate. Measurements have been performed at 14 and 19°C. Pressure exposure induces an increase of glycolytic flux and a decrease of the time needed for the transition from aerobic to anaerobic glycolysis. As a consequence pressure-exposed crabs have a higher potential to increase glycolytic flux than control animals at atmospheric pressure. It is concluded that high pressure known to alter numerous enzymes individually, can also modify an overall metabolic pathway.     

Minimal sample requirement for highly multiplexed protein quantification in cell lines and tissues by PCT‐SWATH mass spectrometry

The amount of sample available for clinical and biological proteomic research is often limited and thus significantly restricts clinical and translational research. Recently, we have integrated pressure cycling technology (PCT) assisted sample preparation and SWATH‐MS to perform reproducible proteomic quantification of biopsy‐level tissue samples. Here, we further evaluated the minimal sample requirement of the PCT‐SWATH method using various types of samples, including cultured cells (HeLa, K562, and U251, 500 000 to 50 000 cells) and tissue samples (mouse liver, heart, brain, and human kidney, 3–0.2 mg). The data show that as few as 50 000 human cells and 0.2–0.5 mg of wet mouse and human tissues produced peptide samples sufficient for multiple SWATH‐MS analyses at optimal sample load applied to the system. Generally, the reproducibility of the method increased with decreasing tissue sample amounts. The SWATH maps acquired from peptides derived from samples of varying sizes were essentially identical based on the number, type, and quantity of identified peptides. In conclusion, we determined the minimal sample required for optimal PCT‐SWATH analyses, and found smaller sample size achieved higher quantitative accuracy.     

囊肿去顶减压术是否改善肾功能的动物实验研究

目的:通过模型加压兔子肾脏,监测加压前后肾功能变化,论证压力对肾功能的影响,根据实验结果给多囊肾临床治疗提供借鉴。方法:将成年新西兰兔随机分为三组(A,B,C),A组兔子切除一侧肾脏,另一侧肾脏通过模型固定圆形气泡予肾脏加压;B组兔子切除一侧肾脏,另一侧肾脏通过模型固定塑料圆球予肾脏加压;C组兔子切除一侧肾脏,另一侧肾脏不予加压处理。分别监测实验组和对照组兔子术前术后肾功的变化(血肌酐、尿素)。对不同加压肾脏标本进行HE、masson和六氨银染色,了解肾脏加压后的病理改变。结果:实验组A行加压术后肾功相对术前与对照组C相比无明显差异;实验组B行加压术后,肌酐、尿素升高明显,与术前、实验组A、对照组C比较均有明显差异(P<0.01)。实验组C一侧肾切除后相比术前肾功能无明显差异。病理示:肾脏加压后,肾小球、肾小管、肾血管继发一系列损害肾功的病理改变。结论:对肾脏施加的压力足够大的时候,压力致使肾脏发生相应病理改变,肌酐、尿素升高,肾功能明显下降。因此传统的囊肿去顶减压术,仍是有意义的对症治疗手段。     

Crystal structure, magnetic properties and Mössbauer studies of [Fe(qsal)2][Ni(dmit)2]

A new compound of formula [Fe(qsal)₂][Ni(dmit)₂] (1) has been synthesised, structurally and magnetically characterised (qsalH = N-(8-quinolyl)salicylaldimine, dmit²⁻ = 1,3-dithiol-2-thione-4,5-dithiolato). Its structural features and its magnetic behaviour were compared with those of [Fe(qsal)₂]-based complexes, and more particularly [Fe(qsal)₂][Ni(dmit)₂] · 2CH₃CN.     

Survival and growth of two heterotrophic hydrothermal vent archaea, <Emphasis Type="Italic">Pyrococcus</Emphasis> strain GB-D and <Emphasis Type="Italic">Thermococcus fumicolans</Emphasis>, under low pH and high sulfide concentrations in combination with high temperature and pressure regimes

Growth and survival of hyperthermophilic archaea in their extreme hydrothermal vent and subsurface environments are controlled by chemical and physical key parameters. This study examined the effects of elevated sulfide concentrations, temperature, and acidic pH on growth and survival of two hydrothermal vent archaea (Pyrococcus strain GB-D and Thermococcus fumicolans) under high temperature and pressure regimes. These two strains are members of the Thermococcales, a family of hyperthermophilic, heterotrophic, sulfur-reducing archaea that occur in high densities at vent sites. As actively growing cells, these two strains tolerated regimes of pH, pressure, and temperature that were in most cases not tolerated under severe substrate limitation. A moderate pH of 5.5–7 extends their survival and growth range over a wider range of sulfide concentrations, temperature and pressure, relative to lower pH conditions. T. fumicolans and Pyrococcus strain GB-D grew under very high pressures that exceeded in-situ pressures typical of hydrothermal vent depths, and included deep subsurface pressures. However, under the same conditions, but in the absence of carbon substrates and electron acceptors, survival was generally lower, and decreased rapidly when low pH stress was combined with high pressure and high temperature. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

一次性可调压限压式灌肠器的实验研究

目的:研究一次性可调压限压式灌肠器的性能。方法:建立模型,测定模拟体内环境下灌肠治疗时肠管各点的压力和灌肠器可调压限压阀开启时的压力是否一致。结果:测定模拟肠管各点压力与灌肠器的可调压限压阀开启时压力一致。结论:一次性可调压限压式灌肠器的性能达到设计要求,操作简便,具有科学性、稳定性、安全性,值得推广。