影响术后机械通气患者撤机的相关参数分析

目的：探讨影响术后机械通气患者呼吸机撤离的相关参数,寻找具有预测价值的指标,为指导临床撤机时机提供依据。方法：选择术后机械通气后准备撤机的患者68例,记录撤机开始时的血流动力学指标,包括心率（HR）、收缩压（SBP）、舒张压（DBP）、平均动脉压（MAP）;呼吸力学指标,包括呼吸频率（RR）、潮气量（VT）、分钟通气量（MV）、浅快呼吸指数（RSBI）、肺顺应性（Crs）、气道峰压（Ppeak）、气道闭合压（P0.1）;血气分析指标,包括血乳酸浓度（lac）、动脉血pH值（pHa）、动脉血氧分压（PaO2）、动脉血二氧化碳分压（PaCO2）、动脉血氧饱和度（SaO2）,并计算氧合指数（PaO2/FiO2）;胃黏膜酸度包括胃黏膜pH值（pHi）、胃黏膜二氧化碳分压（PgCO2）。低水平（5-8 cmH2O）压力支持通气下行60 min自主呼吸实验,按撤机结果分为撤机成功组和撤机失败组。应用SPSS12.0软件包对数据进行统计学分析,采用χ2检验和t检验筛选与撤机有关的阳性指标,采用Logistic回归分析阳性指标中与撤机相关的参数。结果：68例术后机械通气患者完成了本实验,其中撤机成功患者42例,撤机成功率为61.8%。单因素分析表明,RR、VT、RSBI、Ppeak、pHi、PgCO2是与撤机有关的阳性指标（P〈0.05）。Logistic多因素回归分析表明,RSBI、P0.1、pHi是影响撤机的相关参数（P〈0.05）。结论：RR、VT、RSBI、Ppeak、pHi、PgCO2是与撤机有关的阳性指标,而RSBI、P0.1、pHi是影响撤机的相关参数。     

Apoptosis of human tongue squamous cell carcinoma cell (CAL-27) induced by Lactobacillus sp. A-2 metabolites

Objective

To study the effect of Lactobacillus sp. A-2 metabolites on viability of CAL-27 cells and apoptosis in CAL-27 cells.

Methods

Lactobacillus sp. A-2 metabolites 1 and 2 (LM1 and LM2) were obtained by culturing Lactobacillus sp. A-2 in reconstituted whey medium and whey-inulin medium; the cultured CAL-27 cells were treated with different concentrations of LM1 and LM2 (0, 3, 6, 12, 24, 48 mg/mL) and assayed by methyl thiazolyltetrazolium (MTT) method; morphological changes of apoptotic cell were observed under fluorescence microscopy by acridine orange (Ao) fluorescent staining; flow cytometry method (FCM) and agarose gel electrophoresis were used to detect the apoptosis of CAL-27 cells treated LM1 and LM2.

Results

The different concentrations of LM1 and LM2 could restrain the growth of CAL-27 cells, and in a dose-dependent manner; the apoptosis of CAL-27 cells was obviously induced and was time-dependent.

Conclusions

Viability of CAL-27 cells was inhibited by Lactobacillus sp. A-2 metabolites; Lactobacillus sp. A-2 metabolites could induce CAL-27 cells apoptosis; study on the bioactive compounds in the Lactobacillus sp. A-2 metabolites and their molecular mechanism is in progress.     

From the Cover: Molecular determinants of Hv1 proton channel inhibition by guanidine derivatives

The voltage-gated proton channel Hv1 plays important roles in proton extrusion, pH homeostasis, and production of reactive oxygen species in a variety of cell types. Excessive Hv1 activity increases proliferation and invasiveness in cancer cells and worsens brain damage in ischemic stroke. The channel is composed of two subunits, each containing a proton-permeable voltage-sensing domain (VSD) and lacking the pore domain typical of other voltage-gated ion channels. We have previously shown that the compound 2-guanidinobenzimidazole (2GBI) inhibits Hv1 proton conduction by binding to the VSD from its intracellular side. Here, we examine the binding affinities of a series of 2GBI derivatives on human Hv1 channels mutated at positions located in the core of the VSD and apply mutant cycle analysis to determine how the inhibitor interacts with the channel. We identify four Hv1 residues involved in the binding: aspartate 112, phenylalanine 150, serine 181, and arginine 211. 2GBI appears to be oriented in the binding site with its benzo ring pointing to F150, its imidazole ring inserted between residue D112 and residues S181 and R211, and the guanidine group positioned in the proximity of R211. We also identify a modified version of 2GBI that is able to reach the binding site on Hv1 from the extracellular side of the membrane. Understanding how compounds like 2GBI interact with the Hv1 channel is an important step to the development of pharmacological treatments for diseases caused by Hv1 hyperactivity.The Hv1 voltage-gated proton channel (also known as HVCN1 or voltage-sensor–only protein) regulates the production of superoxide and other reactive oxygen species by NADPH oxidase (NOX) enzymes in a variety of cell types, including microglial cells (1) and leukocytes (2). NOX activity causes membrane depolarization and intracellular accumulation of protons. Hv1 allows sustained NOX activity by repolarizing the membrane and extruding excess protons from the cell (3–5).Hv1 has been shown to enhance brain damage in a mouse model of ischemic stroke through its NOX-modulating activity (1). The channel was also found overexpressed in many B-cell malignancies (6) and breast and colorectal cancer tissues (7, 8). High Hv1 activity was shown to increase invasiveness of breast cancer cells and be associated with shorter overall and recurrence-free survival in breast cancer patients (7). These findings highlight that excessive activity of the Hv1 channel can have serious pathological consequences in ischemic stroke and cancer and that small-molecule inhibitors targeting Hv1 could lead to the development of new neuroprotective or anticancer drugs.The Hv1 protein is made of four membrane-spanning segments (S1–S4) (9, 10), and it is related to the voltage-sensing domains (VSDs) of other voltage-gated ion channels (11) and voltage-sensitive phosphatases (VSPs) (12). The inner end of the S4 segment is connected to a coiled-coil domain responsible for protein dimerization (13, 14). As a result, the channel is made of two VSD subunits, each containing a gated proton pore (15–17).The block of voltage-gated sodium, potassium, and calcium channels by small molecules has been studied for decades. Its mechanism has been elucidated for many drugs, and in the majority of cases, the inhibitors were found to bind to different regions of the pore domain (18, 19). With the exception of peptide toxins (20, 21), not much is known about compounds interacting with VSDs (22), and only recently have there been successful attempts to produce small-molecule drugs that specifically target these domains in voltage-gated ion channels (23, 24).We have recently shown that some guanidine derivatives have the ability to inhibit Hv1 activity and that one of these compounds, 2-guanidinobenzimidazole (2GBI), binds the channel''s VSD only in the open conformation (25). We have also found that the binding site is within the proton permeation pathway and faces the cytoplasm.Here, we explore the chemical space available to guanidine derivatives for Hv1 binding. We then use a mutation cycle analysis approach to identify the residues in the channel that contribute to the binding environment of 2GBI and establish the overall orientation of the blocker within the VSD in the open conformation. Our results suggest that residues D112, F150, S181, and R211 are located close to each other deep within the membrane and in the proximity of the intracellular vestibule of the VSD, where they can interact with the blocker. We discuss our binding model in the context of a recent crystal structure of the channel (26).     

Systematic determination of absolute absorption cross-section of individual carbon nanotubes

Optical absorption is the most fundamental optical property characterizing light–matter interactions in materials and can be most readily compared with theoretical predictions. However, determination of optical absorption cross-section of individual nanostructures is experimentally challenging due to the small extinction signal using conventional transmission measurements. Recently, dramatic increase of optical contrast from individual carbon nanotubes has been successfully achieved with a polarization-based homodyne microscope, where the scattered light wave from the nanostructure interferes with the optimized reference signal (the reflected/transmitted light). Here we demonstrate high-sensitivity absorption spectroscopy for individual single-walled carbon nanotubes by combining the polarization-based homodyne technique with broadband supercontinuum excitation in transmission configuration. To our knowledge, this is the first time that high-throughput and quantitative determination of nanotube absorption cross-section over broad spectral range at the single-tube level was performed for more than 50 individual chirality-defined single-walled nanotubes. Our data reveal chirality-dependent behaviors of exciton resonances in carbon nanotubes, where the exciton oscillator strength exhibits a universal scaling law with the nanotube diameter and the transition order. The exciton linewidth (characterizing the exciton lifetime) varies strongly in different nanotubes, and on average it increases linearly with the transition energy. In addition, we establish an empirical formula by extrapolating our data to predict the absorption cross-section spectrum for any given nanotube. The quantitative information of absorption cross-section in a broad spectral range and all nanotube species not only provides new insight into the unique photophysics in one-dimensional carbon nanotubes, but also enables absolute determination of optical quantum efficiencies in important photoluminescence and photovoltaic processes.Single-walled carbon nanotubes (SWNTs), a model one-dimensional nanomaterial system, constitute a rich family of structures (1). Each single-walled nanotube structure, uniquely defined by the chiral index (n,m), exhibits distinct electrical and optical properties (2–5). Quantitative information of SWNT absorption cross-section is highly desirable for understanding nanotube electronic structures, for evaluating quantum efficiency of nanotube photoluminescence (5, 6) and photocurrent (7–9), and for investigating the unique many-body effects in 1D systems (10–16). Despite its obvious importance, reliable experimental determination of nanotube absorption cross-section at the single-tube level is still challenging (17). Previous absorption measurements on ensemble nanotube samples only provide averaged behavior (18–20). Recent absorption studies of individual nanotubes, suffering from small absorption signals and/or slow laser-frequency scanning, cannot determine the absolute absorption cross-section and are limited in achievable spectral range (15, 21–23).We demonstrate here a high-sensitivity polarization-based homodyne method to measure nanotube absorption spectra. By manipulating the light polarization, we enhanced the nanotube-induced transmission contrast, ΔI/I, by two orders of magnitude, and this enhanced transmission contrast can be quantitatively related to nanotube absorption cross-section along and perpendicular to the nanotube axis. Using this polarization control together with supercontinuum laser source, we realized high-throughput and broadband absorption measurements at the single-tube level; combined with electron diffraction technique on the same tube, it enables absolute determination of absorption cross-sections of individual chirality-defined nanotubes, to our knowledge for the first time. We obtained quantitative absorption spectra of over 50 SWNTs of different chiralities, and established a phenomenological formula for absorption cross-sections of different nanotubes. The chirality-dependent nanotube absorption spectra reveal unique 1D photophysics in nanotubes, including a universal scaling behavior of exciton oscillator strength and of exciton resonance linewidth.     

Clinical status of Sagliker syndrome: a case report and literature review

In a 53-year-old woman, Sagliker syndrome developed during 22 years of treatment with intermittent hemodialysis as a result of severe secondary hyperparathyroidism (SHPT) complicating end-stage renal disease. She failed medical managements and lost her renal graft just after the kidney transplantation due to acute rejection. Although surgical parathyroidectomy was effective, the parathyroid hormone level became extremely high again due to recurrent hyperparathyroidism. It is possible that such patient could survive long-term with dialysis, but prevention of severe SHPT is the most important.     

Risk factors for acute kidney injury (AKI) in infants with melamine-associated urolithiasis and follow-up: a multi-center retrospective analysis

An epidemic of urinary tract stones was noted among infants in China, 2008. This event was believed to be associated with consumption melamine-contaminated powdered formula. The patients with symptoms and clinical manifests had already been analyzed in our previous studies. In this study, our aim is to investigate the risk factors of melamine-associated acute kidney injury (AKI) and the potential relationship toward children growth in our five years follow-up. A total of 619 infants with melamine-associated urolithiasis were admitted into 20 different hospitals in the Gansu province, China. All clinical data were divided into AKI and control groups according to the occurrence of AKI. Univariate and multivariate analyses were performed with a logistic regression model to assess the independent risk factors of AKI. Logistic regression analysis revealed that the odds ratio (OR) of AKI was 19.62 in the group of infants who consumed Sanlu® milk powdered infant milk formula. A higher prevalence of AKI was observed in infants age of 6–11 months (OR: 9.59, p?p?p?相似文献