Publications by authors named "Yizhao Chen"

36 Publications

Digital in-service relative time delay estimation for SDM self-homodyne coherent systems.

Opt Express 2021 Nov;29(24):39079-39095

For space division multiplexing self-homodyne coherent systems, we propose a novel digital in-service relative time delay (RTD) estimation method without any additional optoelectronic device. Taking advantage of the frequency-domain periodicity of the colored frequency modulation noise, we manage to find the peak with location reflecting the RTD in its autocorrelation function (ACF). The peak to average ratio is further enhanced by leveraging a low-pass differential finite impulse response filter for robust identification. By simulations, the method is validated to be feasible for various linewidths, formats (16QAM, 32QAM and 64QAM), and links up to 80 km. Particularly, it is proved to be inherently compatible with large-linewidth low-cost lasers for the 10-km link. Also, for a low-complexity implementation, we discuss the way to reduce the number of points used to calculate the ACF while maintaining the same dynamic range. Furthermore, we demonstrate a 50-GBaud 16-QAM experiment to investigate its performances. With received optical power varying from -11 dBm to -17 dBm, 2 points are sufficient to provide an estimation accuracy of standard deviation (STD) less than 0.089 ns for the RTD range of [2.6, 491.0 ns]. The STD can be lowered to 0.036 ns by adopting 2 points. Especially, at -11-dBm ROP, the highest performance has been achieved with an accuracy smaller than the symbol period (0.018-ns STD) and a RTD range of [1.5, 491.0 ns].
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.442919DOI Listing
November 2021

Characteristics of the Dynamic Electrocardiogram in the Elderly with Nonvalvular Atrial Fibrillation Combined with Long R-R Intervals.

Evid Based Complement Alternat Med 2021 10;2021:4485618. Epub 2021 Nov 10.

ECG Diagnosis Department, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, China.

Objective: To investigate the characteristics of dynamic electrocardiogram and their clinical implications in elderly patients with nonvalvular atrial fibrillation combined with long R-R intervals.

Methods: Elderly patients diagnosed with nonvalvular atrial fibrillation who were admitted as an inpatient or attended the outpatient department from January 2015 to January 2020 were selected. Patients were divided into two groups based on the presence of a long R-R interval. The characteristics and therapeutic significance of dynamic electrocardiogram between the two groups were compared.

Results: A total of 532 patients were included in our analyses. Of these, 399 patients were in the long R-R interval group and 133 in the nonlong R-R interval group. In 399 patients, there were 48,840 long R-R intervals manifested within 24 hours. The average, slowest, and fastest ventricular rates during sleep time were higher than those in nonsleep time, while the number of long R-R intervals in sleep time was significantly smaller than that in nonsleep time ( < 0.05). Clinical parameters including dizziness/syncope, cerebral infarction, ST-segment changes, platelet count, average hematocrit, prothrombin time (PT), left ventricular systolic function, end-diastolic diameter, pulmonary artery pressure, and left ventricular ejection fraction were comparable between the groups ( > 0.05). When compared with the nonlong R-R interval group, the level of C-reactive protein was slightly lower in the long R-R interval group ( < 0.05). In addition, the long R-R interval group had a higher incidence of atrial premature beats but a lower incidence of ventricular premature beats. Furthermore, the probability of long R-R interval combined with paroxysmal atrial tachycardia, transient ventricular arrest, second-degree atrioventricular block, and complete or incomplete right bundle branch block was higher than that of nonlong R-R interval ( < 0.05). In patients with long R-R interval >3 s, the risk of having second-degree atrioventricular block and complete or incomplete right bundle branch block was significantly lower, while the risk of having transient ventricular arrest was higher when compared to patients with long R-R intervals of 2-3 s ( < 0.05).

Conclusions: Long R-R interval is a common electrocardiographic phenomenon among the elderly with nonvalvular atrial fibrillation. The long R-R interval mostly occurs in nonsleeping time. The average ventricular rate, slowest ventricular rate, and fastest ventricular rate of sleep time are higher than nonsleeping time. Analysis of the characteristics of the dynamic electrocardiogram of these patients may shed light on the mechanisms for long R-R intervals, including the likelihood of concealed conduction and physiological interference in the atrioventricular node, overspeed inhibition, increased vagus nerve tension, or pathological atrioventricular block.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1155/2021/4485618DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8598370PMC
November 2021

Geometric shaping optimization of 64-APSK constellation in discrete nonlinear frequency division multiplexing systems.

Opt Lett 2021 Jul;46(14):3368-3371

We experimentally demonstrated a geometric shaped (GS) 64-ary amplitude phase shift keying (64-APSK) eigenvalue transmission. The signal is modulated on the scatter coefficient of a single eigenvalue and linear minimum mean square error (LMMSE) estimator is used to reduce the noise. The channel response is estimated by transmitting a normally distributed 64-APSK constellation through a communication link. Based on the polar coordinates distribution of the received constellation, the diameter distributions for each circle can be obtained so that circles with larger noise can obtain larger judgment width. After optimization, the experimental results show that the Q-factor gain is 1.13 dB under 22 dB received optical signal to noise ratio (OSNR) configuration and 0.88 dB after 900 km transmission compared with normally distributed APSK configuration.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.430391DOI Listing
July 2021

Puerarin attenuates intracerebral hemorrhage-induced early brain injury possibly by PI3K/Akt signal activation-mediated suppression of NF-κB pathway.

J Cell Mol Med 2021 08 27;25(16):7809-7824. Epub 2021 Jun 27.

Department of Neurosurgery, Zhujiang Hospital, The Engineering Technology Research Center of Education Ministry of China, The National Key Clinical Specialty, The Neurosurgery Institute of Guangdong Province, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Southern Medical University, Guangzhou, China.

Intracerebral hemorrhage (ICH) can induce intensively oxidative stress, neuroinflammation, and brain cell apoptosis. However, currently, there is no highly effective treatment available. Puerarin (PUE) possesses excellent neuroprotective effects by suppressing the NF-κB pathway and activating the PI3K/Akt signal, but its role and related mechanisms in ICH-induced early brain injury (EBI) remain unclear. In this study, we intended to observe the effects of PUE and molecular mechanisms on ICH-induced EBI. ICH was induced in rats by collagenase IV injection. PUE was intraperitoneally administrated alone or with simultaneously intracerebroventricular injection of LY294002 (a specific inhibitor of the PI3K/Akt signal). Neurological deficiency, histological impairment, brain edema, hematoma volume, blood-brain barrier destruction, and brain cell apoptosis were evaluated. Western blot, immunohistochemistry staining, reactive oxygen species (ROS) measurement, and enzyme-linked immunosorbent assay were performed. PUE administration at 50 mg/kg and 100 mg/kg could significantly reduce ICH-induced neurological deficits and EBI. Moreover, PUE could notably restrain ICH-induced upregulation of the NF-κB pathway, pro-inflammatory cytokines, ROS level, and apoptotic pathway and activate the PI3K/Akt signal. However, LY294002 delivery could efficaciously weaken these neuroprotective effects of PUE. Overall, PUE could attenuate ICH-induced behavioral defects and EBI possibly by PI3K/Akt signal stimulation-mediated inhibition of the NF-κB pathway, and this made PUE a potential candidate as a promising therapeutic option for ICH-induced EBI.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jcmm.16679DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8358853PMC
August 2021

All-optical polarization split of the signal and LO for a bi-directional self-homodyne coherent system.

Opt Lett 2021 Jun;46(12):2819-2822

In this Letter, we propose a cost-efficient bi-directional (BiDi) polarization-multiplexed self-homodyne coherent detection (SHCD) system, in which only one fiber link and one adaptive polarization controller (APC) are required. By employing the correlation of the state of polarization (SOP) between the upstream and downstream light, one APC is capable of stabilizing SOPs of the counterpropagating waves at the same time. The signal and local oscillator (LO) can be optically split by a polarization beam splitter (PBS), relaxing pressure of the digital signal processing (DSP) and simplifying the coherent receiver. The impact induced by polarization cross talk and delay mismatch is collectively investigated by theoretical analysis and simulation. Finally, the proposed scheme is experimentally verified through 120 Gbit/s 16-quadrature amplitude modulation (16-QAM) transmission, achieving a satisfying laser-linewidth tolerance of 10 MHz and a polarization rotation tolerance of up to 45 rad/s.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.427789DOI Listing
June 2021

Manipulating phloem transport affects wood formation but not local nonstructural carbon reserves in an evergreen conifer.

Plant Cell Environ 2021 08 21;44(8):2506-2521. Epub 2021 Jun 21.

School of Informatics, Computing, and Cyber Security, Northern Arizona University, Flagstaff, Arizona, USA.

How variations in carbon supply affect wood formation remains poorly understood in particular in mature forest trees. To elucidate how carbon supply affects carbon allocation and wood formation, we attempted to manipulate carbon supply to the cambial region by phloem girdling and compression during the mid- and late-growing season and measured effects on structural development, CO efflux and nonstructural carbon reserves in stems of mature white pines. Wood formation and stem CO efflux varied with a location relative to treatment (i.e., above or below the restriction). We observed up to twice as many tracheids formed above versus below the treatment after the phloem transport manipulation, whereas the cell-wall area decreased only slightly below the treatments, and cell size did not change relative to the control. Nonstructural carbon reserves in the xylem, needles and roots were largely unaffected by the treatments. Our results suggest that low and high carbon supply affects wood formation, primarily through a strong effect on cell proliferation, and respiration, but local nonstructural carbon concentrations appear to be maintained homeostatically. This contrasts with reports of decoupling of source activity and wood formation at the whole-tree or ecosystem level, highlighting the need to better understand organ-specific responses, within-tree feedbacks, as well as phenological and ontogenetic effects on sink-source dynamics.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/pce.14117DOI Listing
August 2021

CAR-macrophage: A new immunotherapy candidate against solid tumors.

Biomed Pharmacother 2021 Jul 23;139:111605. Epub 2021 Apr 23.

Institute of Clinical Pharmacology, Anhui Medical University, Key Laboratory of Anti-Inflammatory and Immune Medicine, Ministry of Education, Anhui Collaborative Innovation Center of Anti-Inflammatory and Immune Medicine, Hefei, China; Department of Gynecology, The First Affiliated Hospital of Shenzhen University, Health Science Center; Shenzhen Second People's Hospital, Shenzhen, China. Electronic address:

Chimeric antigen receptor (CAR)-T cell therapy has been shown to be an effective treatment for hematological tumors, but the treatment of solid tumors still lacks effectiveness. In the tumor microenvironment, macrophages are the innate immune cells with the highest infiltration rate. Tumor-associated macrophages (TAMs) stimulate angiogenesis, increase tumor invasion, and mediate immunosuppression. Because macrophages can infiltrate solid tumor tissue and interact with almost all cellular components in the tumor microenvironment (including tumor cells, immune cells such as T-cells, NK cells, DCs, and other resident non-immune cells), researchers are trying to use macrophages modified with CAR (CAR-M) against solid tumors. This review describes recent reports of CAR-M-based tumor treatments and summarizes their shortcomings and future applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.biopha.2021.111605DOI Listing
July 2021

Inhibition of NOX4/ROS Suppresses Neuronal and Blood-Brain Barrier Injury by Attenuating Oxidative Stress After Intracerebral Hemorrhage.

Front Cell Neurosci 2020 13;14:578060. Epub 2020 Nov 13.

Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang Hospital, The National Key Clinical Specialty, The Neurosurgery Institute of Guangdong Province, The Engineering Technology Research Center of Education Ministry of China, Southern Medical University, Guangzhou, China.

Intracerebral hemorrhage (ICH) is a common and severe neurological disorder that can effectively induce oxidative stress responses. NADPH oxidase 4 (NOX4) is a member of the NOX family of oxidases. It is expressed in the brain normally and involved in cell signal transduction and the removal of harmful substances. In some pathological conditions, it mediates inflammation and the aging of cells. However, few studies have focused on whether NOX4 is involved in brain injury caused by ICH. Therefore, this study aimed to clarify the role of NOX4 in the pathological process that occurs after ICH and the potential mechanism underlying its role. A rat model of ICH was established by the injection of collagenase type IV, and the expression of NOX4 was then determined. Further, siRNA-mediated protein expression knockdown technology was used for NOX4 knockdown, and western immunoblotting, immunohistochemistry, immunofluorescence, enzyme-linked immunosorbent assay (ELISA), and other molecular biological techniques were performed to assess the effects of NOX4 knockdown. Neurobiological scoring, brain water content determination, and other brain injury detection methods were also performed to assess the role of NOX4 following ICH. We found that the expression of NOX4 increased in the brains of rats after ICH, and that it was mainly expressed in neurons, astrocytes, vascular endothelial cells and microglia. Following NOX4 knockdown, the level of oxidative stress in the brain decreased considerably, the neurobehavioral scores improved, the levels of neuronal apoptosis reduced markedly, and the impairment of blood-brain barrier function was significantly ameliorated in rats with ICH. In conclusion, this study suggests that NOX4 expression is upregulated after ICH, which may cause an imbalance in the oxidative stress of relevant cells in the brain, leading to subsequent apoptosis of neurons and damage to the blood-brain barrier due to secondary brain injury following ICH.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fncel.2020.578060DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7691600PMC
November 2020

Measurement of urine albumin by liquid chromatography-isotope dilution tandem mass spectrometry and its application to value assignment of external quality assessment samples and certification of reference materials.

Clin Chem Lab Med 2021 03 20;59(4):711-720. Epub 2020 Oct 20.

Department of Laboratory Medicine, National University Hospital, Singapore, Singapore.

Objectives: Urine albumin is measured in clinical laboratories by immunoturbidimetry. However, large biases are observed among the different routine methods. To standardize the measurement of urine albumin, a reference measurement procedure (RMP) and urine albumin certified reference materials (CRMs) are needed.

Methods: A candidate RMP for urine albumin based on liquid chromatography-isotope dilution tandem mass spectrometry (LC-IDMS/MS) using human serum albumin as calibration standard was developed. Isotope-labeled human albumin was used as internal standard. Urine samples were digested using trypsin and eight resulting "signature" peptides of albumin were quantified by LC-IDMS/MS. The candidate RMP was employed in value assignment of external quality assessment (EQA) samples and certification of urine albumin reference materials. The commutability of the developed CRMs was assessed against patient samples.

Results: The candidate RMP (recovery 101.5-103.2% and CV 1.2-3.3% at about 7-40 mg/L) met optimal performance goal. The lower limit of quantification was 0.03 mg/L as determined by signal-to-noise method. The EQA results from clinical laboratories using different immunoturbidimetric methods were generally comparable with assigned target values determined by the candidate RMP, with albumin concentrations ranging from 5 to 226 mg/L. Urine albumin reference materials (two levels) certified using the candidate RMP showed good commutability in a preliminary study.

Conclusions: With optimal method precision and trueness, as well as comparability with routine methods, the developed RMP may be used for value assignment of EQA samples or certification of reference materials, which are important pillars in urine albumin method standardization.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1515/cclm-2020-0969DOI Listing
March 2021

Direct response of tree growth to soil water and its implications for terrestrial carbon cycle modelling.

Glob Chang Biol 2021 Jan 10;27(1):121-135. Epub 2020 Nov 10.

Department of Geography, University of Cambridge, Cambridge, UK.

Wood growth constitutes the main process for long-term atmospheric carbon sequestration in vegetation. However, our understanding of the process of wood growth and its response to environmental drivers is limited. Current dynamic global vegetation models (DGVMs) are mainly photosynthesis-driven and thus do not explicitly include a direct environmental effect on tree growth. However, physiological evidence suggests that, to realistically model vegetation carbon allocation under increased climatic stressors, it is crucial to treat growth responses independently from photosynthesis. A plausible growth response function suitable for global simulations in DGVMs has been lacking. Here, we present the first soil water-growth response function and parameter range for deciduous and evergreen conifers. The response curve was calibrated against European larch and Norway spruce in a dry temperate forest in the Swiss Alps. We present a new data-driven approach based on a combination of tree ring width (TRW) records, growing season length and simulated subdaily soil hydrology to parameterize ring width increment simulations. We found that a simple linear response function, with an intercept at zero moisture stress, used in growth simulations reproduced 62.3% and 59.4% of observed TRW variability for larch and spruce respectively and, importantly, the response function slope was much steeper than literature values for soil moisture effects on photosynthesis and stomatal conductance. Specifically, we found stem growth stops at soil moisture potentials of -0.47 MPa for larch and -0.66 MPa for spruce, whereas photosynthesis in trees continues down to -1.2 MPa or lower, depending on species and measurement method. These results are strong evidence that the response functions of source and sink processes are indeed very different in trees, and need to be considered separately to correctly assess vegetation responses to environmental change. The results provide a parameterization for the explicit representation of growth responses to soil water in vegetation models.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/gcb.15397DOI Listing
January 2021

Determination of purity values of amino acid reference materials by mass balance method: an approach to the quantification of related structure impurities.

Anal Bioanal Chem 2020 Nov 10;412(29):8023-8037. Epub 2020 Sep 10.

Chemical Metrology Division, Applied Sciences Group, Health Sciences Authority, 1 Science Park Road, #01-05/06, The Capricorn, Singapore Science Park II, Singapore, 117528, Singapore.

A systematic procedure for the determination of purity values of amino acid reference materials was developed by use of mass balance method where four categories of impurities (related structure impurities (RSIs), water, organic solvent residue (OSR), and non-volatile residue (NVR)) were quantified separately. The amount of RSIs was determined using a combination of three quantification methods. To ensure metrological traceability in the determination of RSIs, at least one such impurity in each candidate amino acid reference material was quantified using liquid chromatography-isotope dilution tandem mass spectrometry (LC-IDMS/MS). Other RSIs were determined using external calibration liquid chromatography-tandem mass spectrometry (LC-MS/MS) or o-phthaldialdehyde (OPA) derivatization, followed by liquid chromatography-ultraviolet (LC-UV) measurement. As the UV absorption of most RSIs came basically from the same chromophore after OPA derivatization, a relative peak area approach was used in the LC-UV method to quantify the amount of RSIs by comparing their peak areas with that of a reference RSI. The reference RSI was pre-selected and the amount determined by LC-IDMS/MS separately. The absence of D-amino acids was confirmed using Marfey's reagent derivatization, followed by LC-UV analysis. The amounts of water, OSR, and NVR were measured using Karl Fischer coulometry, gas chromatography-mass spectrometry (GC-MS) and thermogravimetry, respectively. By using this procedure, four amino acid (L-valine, L-leucine, L-isoleucine, and L-phenylalanine) certified reference materials (CRMs) were developed from the candidate materials. The homogeneity and stability of the CRMs were demonstrated by use of LC-IDMS/MS or OPA-LC-UV method, following the principles in ISO 17034 and ISO Guide 35.Graphical abstract.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00216-020-02936-7DOI Listing
November 2020

Procyanidins exhibits neuroprotective activities against cerebral ischemia reperfusion injury by inhibiting TLR4-NLRP3 inflammasome signal pathway.

Psychopharmacology (Berl) 2020 Nov 29;237(11):3283-3293. Epub 2020 Jul 29.

Department of Neurosurgery, Zhujiang Hospital, The National Key Clinical Specialty, The Neurosurgery Institute of Guangdong Province, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Engineering Technology Research Center of Education Ministry of China, Southern Medical University, Guangzhou, 510282, China.

Background: Ischemic stroke is a serious cardiovascular disease with high morbidity and mortality rates that affects millions of people worldwide.Currently, the only therapy with proven efficacy for acute ischemic stroke is alteplase, however, it still has many shortcomings and limitations. Therefore,we screen new compounds from traditional Chinese medicine to explore their efficacy against ischemic reperfusion injury. Procyanidins, a natural productextracted from grapes seed, which have been shown can ameliorate cerebral ischemic injury. However, the underlying mechanism is still not very clear. Theaim of this study was to investigate the effect of procyanidins on middle cerebral artery occlusion/reperfusion (MCAO/R)-mediated cerebral ischemic injuryand its underlying possible mechanisms.

Methods: SD rats were used to evaluate the effect of procyanidins on MCAO/R induced cerebral ischemic injury in vivo. Histological analysis was used toassess neuronal apoptosis. Cell signaling was assayed by Western blot.

Results: In this study, we found that procyanidins can significantly ameliorate the middle cerebral artery occlusion/reperfusion (MCAO/R)-mediatedneurological deficits, and relieved brain edema, cerebral infarction volume, histopathological damage and apoptosis in rats. In addition, procyanidins canalso markedly inhibit MCAO/R and oxygen-glucose deprivation/reoxygenation (OGD/R)-mediated activation of TLR4-p38-NF-κB-NLRP3 signalingpathway in vitro and in vivo. Moreover, procyanidins can inhibit MCAO/R and OGD/R-induced the production of inflammatory cytokines such asinterleukin-1β (IL-1β) in vitro and in vivo. Besides, treatment with TLR4 inhibitor (Cli-095) in BV2 cell also shows the same effect.

Conclusion: Altogether, these data suggested that procyanidins exerted a potential neuroprotective effect may by inhibit the TLR4-p38-NF-κB-NLRP3signaling pathway in the brain in MCAO/R rats.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00213-020-05610-zDOI Listing
November 2020

Isocyanoacetate-Aldehyde Polymerization: A Facile Tool toward Functional Oxazoline-Containing Polymers.

Macromol Rapid Commun 2020 Jun 28;41(12):e2000179. Epub 2020 May 28.

State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, Center for Aggregation-Induced Emission, South China University of Technology, Guangzhou, 510640, China.

As an important nitrogen source, isocyanides have been involved in numerous organic reactions. As a result, many complicated compounds have been successfully synthesized through isocyanide chemistry. However, compared with its popular research in organic reactions, the application of isocyanides in polymerization is less investigated. In this work, a new polymerization based on isocyanide monomers is established. By simply mixing diisocyanoacetates and dialdehydes in the presence of a catalytic system of CuCl/PPh /organobase in dichloromethane at room temperature readily produces soluble and thermally stable oxazoline-containing polymers with moderate weight-averaged molecular weights (M up to 11 200) in excellent yields (up to 97%) after 6 h. Furthermore, introducing the tetraphenylethene moiety into the main chains endows the resultant polymers with aggregation-induced emission, which can function as fluorescent probes for Fe ion detection with high sensitivity and selectivity. This work not only enriches the family of isocyanide-based polymerizations but also provides an efficient tool for the preparation of functional heterocycle-containing polymers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/marc.202000179DOI Listing
June 2020

Hybrid constellation entropy loading for adaptively partitioned SSB-DMT systems.

Opt Express 2019 Sep;27(19):26295-26306

In this paper, by adaptively partitioning and precoding the subcarriers, we proposed a practical and effective entropy loading (EL) scheme for single sideband discrete multi-tone (SSB-DMT) systems. To reveal the practical performance, information bits per symbol (IBPS) is used to identify the optimal probabilistically shaped quadrature amplitude modulation (PS-QAM). Under the constraint of normalized generalized mutual information (NGMI) of the off-the-shelf forward error correction (FEC), we obtain the PS-QAMs that achieve the maximum IBPS using different constellations for different signal-to-noise ratio (SNR). Based on the result, we proposed two adaptively partitioning methods, equally partitioned precoding (EPP) and optimally partitioned precoding (OPP), to perform hybrid constellation entropy loading (HCEL). The HCEL with OPP significantly reduces the number of distribution matcher to 3 from generally several hundred of conventional EL with negligible loss of net data rate (NDR). As demonstrated by experiments, the HCEL with OPP achieves 4.4 dB receiver sensitivity gain compared to conventional bit and power loading, Levin-Campello (LC), and 1.2 dB receiver sensitivity gain compared to HCEL with EPP at the NDR of 60 Gb/s after 80 km standard single mode fiber transmission, making it a competitive and practical solution for EL in the short-to-medium reach transmission systems.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.27.026295DOI Listing
September 2019

Simple and accurate candidate reference measurement procedure for total testosterone in human serum by one-step liquid-liquid extraction coupled with isotope dilution mass spectrometry.

Anal Bioanal Chem 2019 Nov 19;411(28):7519-7528. Epub 2019 Oct 19.

Department of Laboratory Medicine, National University Hospital, 5 Lower Kent Ridge Road, Singapore, 119074, Singapore.

Testosterone in human serum is commonly tested in clinical laboratories using immunoassay methods as well as liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. To standardize and ensure the accuracy of the measurement results, reference procedures with higher metrological order are required. A simple measurement procedure based on one-step liquid-liquid extraction (LLE) and liquid chromatography-isotope dilution tandem mass spectrometry (LC-IDMS/MS) was developed for total testosterone in human serum. The procedure involved serum spiked with C-testosterone, equilibration for 2 h, and extraction with an organic solvent. Testosterone certified reference material (CRM) was used as the calibration standard to ensure the traceability to the International System of Units (SI). Testosterone in serum CRMs from the National Institute for Standards and Technology (NIST) and LGC were used to validate the accuracy of the newly developed method. The deviations of the obtained values from the NIST and LGC certified values ranged from -0.55% to 0.45%. Similarly, the coefficient of variations (CVs) of the replicate measurements were in the range of 0.55% and 0.78%, respectively. The relative expanded uncertainties were comparable with those of the certified materials. The newly developed LC-IDMS/MS procedure demonstrated adequate trueness and precision, and was simple to perform. The method can be used for value assignment of testosterone in external quality assessment (EQA) materials as well as certification of CRMs in the future. Graphical abstract.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00216-019-02152-yDOI Listing
November 2019

Sparse-fast-Fourier-transform-based quick synchronization for optical direct detection orthogonal frequency division multiplexing systems.

Opt Lett 2018 May;43(9):2014-2017

Orthogonal frequency division multiplexing (OFDM) has always been a promising candidate for optical access networks. However, it is very sensitive to synchronization errors and requires complex digital signal processing to eliminate this influence, thus increasing the computation complexity, delay, and system cost, which hampers its applications in cost-sensitive and low-latency scenarios of future optical access networks. To deal with this issue, a sparse-fast-Fourier-transform (FFT)-based quick synchronization algorithm for optical direct detection OFDM systems is proposed and demonstrated with greatly reduced computation complexity. Detailed simulations and experimental verifications along 50 km standard single-mode-fiber transmission prove the efficiency, accuracy, and feasibility of the sparse-FFT-based synchronization technique in cost- and delay-sensitive applications for next-generation optical access networks.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.43.002014DOI Listing
May 2018

Quantitative assessments of water-use efficiency in Temperate Eurasian Steppe along an aridity gradient.

PLoS One 2017 7;12(7):e0179875. Epub 2017 Jul 7.

Institute of Geography, Georg-August University Göttingen, Göttingen, Germany.

Water-use efficiency (WUE), defined as the ratio of net primary productivity (NPP) to evapotranspiration (ET), is an important indicator to represent the trade-off pattern between vegetation productivity and water consumption. Its dynamics under climate change are important to ecohydrology and ecosystem management, especially in the drylands. In this study, we modified and used a late version of Boreal Ecosystem Productivity Simulator (BEPS), to quantify the WUE in the typical dryland ecosystems, Temperate Eurasian Steppe (TES). The Aridity Index (AI) was used to specify the terrestrial water availability condition. The regional results showed that during the period of 1999-2008, the WUE has a clear decreasing trend in the spatial distribution from arid to humid areas. The highest annual average WUE was in dry and semi-humid sub-region (DSH) with 0.88 gC mm-1 and the lowest was in arid sub-region (AR) with 0.22 gC mm-1. A two-stage pattern of WUE was found in TES. That is, WUE would enhance with lower aridity stress, but decline under the humid environment. Over 65% of the region exhibited increasing WUE. This enhancement, however, could not indicate that the grasslands were getting better because the NPP even slightly decreased. It was mainly attributed to the reduction of ET over 70% of the region, which is closely related to the rainfall decrease. The results also suggested a similar negative spatial correlation between the WUE and the mean annual precipitation (MAP) at the driest and the most humid ends. This regional pattern reflected the different roles of water in regulating the terrestrial ecosystems under different aridity levels. This study could facilitate the understanding of the interactions between terrestrial carbon and water cycles, and thus contribute to a sustainable management of nature resources in the dryland ecosystems.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0179875PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5501447PMC
October 2017

Isoliquiritigenin alleviates early brain injury after experimental intracerebral hemorrhage via suppressing ROS- and/or NF-κB-mediated NLRP3 inflammasome activation by promoting Nrf2 antioxidant pathway.

J Neuroinflammation 2017 06 13;14(1):119. Epub 2017 Jun 13.

Department of Neurosurgery, Zhujiang Hospital, The National Key Clinical Specialty, The Neurosurgery Institute of Guangdong Province, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Engineering Technology Research Center of Education Ministry of China, Southern Medical University, Guangzhou, 510282, China.

Background: Intracerebral hemorrhage (ICH) induces potently oxidative stress responses and inflammatory processes. Isoliquiritigenin (ILG) is a flavonoid with a chalcone structure and can activate nuclear factor erythroid-2 related factor 2 (Nrf2)-mediated antioxidant system, negatively regulate nuclear factor-κB (NF-κB) and nod-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome pathways, but its role and potential molecular mechanisms in the pathology following ICH remain unclear. The present study aimed to explore the effects of ILG after ICH and underlying mechanisms.

Methods: ICH model was induced by collagenase IV (0.2 U in 1 μl sterile normal saline) in male Sprague-Dawley rats weighing 280-320 g. Different doses of ILG (10, 20, or 40 mg/kg) was administrated intraperitoneally at 30 min, 12 h, 24 h, and 48 h after modeling, respectively. Rats were intracerebroventricularly administrated with control scramble small interfering RNA (siRNA) or Nrf2 siRNA at 24 h before ICH induction, and after 24 h, ICH model was established with or without ILG (20 mg/kg) treatment. All rats were dedicated at 24 or 72 h after ICH. Neurological deficits, histological damages, brain water content (BWC), blood-brain barrier (BBB) disruption, and neuronal degeneration were evaluated; quantitative real-time RT-PCR (qRT-PCR), immunohistochemistry/immunofluorescence, western blot, and enzyme-linked immunosorbent assay (ELISA) were carried out; catalase, superoxide dismutase activities and reactive oxygen species (ROS), and glutathione/oxidized glutathione contents were measured.

Results: ILG (20 and 40 mg/kg) markedly alleviated neurological deficits, histological damages, BBB disruption, brain edema, and neuronal degeneration, but there was no significant difference between two dosages. ILG (20 mg/kg) significantly suppressed the NF-κB and NLRP3 inflammasome pathways and activated Nrf2-mediated antioxidant system. Gene silencing of Nrf2 aggravated the neurological deficits, brain edema, and neuronal degeneration and increased the protein levels of NF-κB p65, NLRP3 inflammasome components, and IL-1β. ILG delivery significantly attenuated the effects of Nrf2 siRNA interference mentioned above.

Conclusions: Intraperitoneal administration of ILG after ICH reduced early brain impairments and neurological deficits, and the mechanisms were involved in the regulation of ROS and/or NF-κB on the activation of NLRP3 inflammasome pathway by the triggering of Nrf2 activity and Nrf2-induced antioxidant system. In addition, our experimental results may make ILG a potential candidate for a novel therapeutical strategy for ICH.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12974-017-0895-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5470182PMC
June 2017

Erratum to: P2X7R blockade prevents NLRP3 inflammasome activation and brain injury in a rat model of intracerebral hemorrhage: involvement of peroxynitrite.

J Neuroinflammation 2016 Aug 17;13(1):186. Epub 2016 Aug 17.

The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12974-016-0627-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4988039PMC
August 2016

Vegetation dynamics and its driving forces from climate change and human activities in the Three-River Source Region, China from 1982 to 2012.

Sci Total Environ 2016 Sep 30;563-564:210-20. Epub 2016 Apr 30.

School of Life Science, Nanjing University, Xianlin Road 163, Qixia District, Nanjing, 210046, China. Electronic address:

The Three-River Source Region (TRSR), a region with key importance to the ecological security of China, has undergone climate changes and a shift in human activities driven by a series of ecological restoration projects in recent decades. To reveal the spatiotemporal dynamics of vegetation dynamics and calculate the contributions of driving factors in the TRSR across different periods from 1982 to 2012, net primary productivity (NPP) estimated using the Carnegie-Ames-Stanford approach model was used to assess the status of vegetation. The actual effects of different climatic variation trends on interannual variation in NPP were analyzed. Furthermore, the relationships of NPP with different climate factors and human activities were analyzed quantitatively. Results showed the following: from 1982 to 2012, the average NPP in the study area was 187.37gcm(-2)yr(-1). The average NPP exhibited a fluctuation but presented a generally increasing trend over the 31-year study period, with an increase rate of 1.31gcm(-2)yr(-2). During the entire study period, the average contributions of temperature, precipitation, and solar radiation to NPP interannual variation over the entire region were 0.58, 0.73, and 0.09gcm(-2)yr(-2), respectively. Radiation was the climate factor with the greatest influence on NPP interannual variation. The factor that restricted NPP increase changed from temperature and radiation to precipitation. The average contributions of climate change and human activities to NPP interannual variation were 1.40gcm(-2)yr(-2) and -0.08gcm(-2)yr(-2), respectively. From 1982 to 2000, the general climate conditions were favorable to vegetation recovery, whereas human activities had a weaker negative impact on vegetation growth. From 2001 to 2012, climate conditions began to have a negative impact on vegetation growth, whereas human activities made a favorable impact on vegetation recovery.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2016.03.223DOI Listing
September 2016

Grazing exclusion reduced soil respiration but increased its temperature sensitivity in a Meadow Grassland on the Tibetan Plateau.

Ecol Evol 2016 02 11;6(3):675-87. Epub 2016 Jan 11.

Department of Microbiology and Plant Biology University of Oklahoma Norman Oklahoma 73019 USA; Center for Earth System Science Tsinghua University Beijing 100084 China.

Understanding anthropogenic influences on soil respiration (R s) is critical for accurate predictions of soil carbon fluxes, but it is not known how R s responds to grazing exclusion (GE). Here, we conducted a manipulative experiment in a meadow grassland on the Tibetan Plateau to investigate the effects of GE on R s. The exclusion of livestock significantly increased soil moisture and above-ground biomass, but it decreased soil temperature, microbial biomass carbon (MBC), and R s. Regression analysis indicated that the effects of GE on R s were mainly due to changes in soil temperature, soil moisture, and MBC. Compared with the grazed blocks, GE significantly decreased soil carbon release by 23.6% over the growing season and 21.4% annually, but it increased the temperature sensitivity (Q10) of R s by 6.5% and 14.2% for the growing season and annually respectively. Therefore, GE may reduce the release of soil carbon from the Tibetan Plateau, but under future climate warming scenarios, the increases in Q10 induced by GE could lead to increased carbon emissions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ece3.1867DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4739563PMC
February 2016

The role of residence time in diagnostic models of global carbon storage capacity: model decomposition based on a traceable scheme.

Sci Rep 2015 Nov 6;5:16155. Epub 2015 Nov 6.

School of Life Science, Nanjing University, Nanjing, P.R. China.

As a key factor that determines carbon storage capacity, residence time (τE) is not well constrained in terrestrial biosphere models. This factor is recognized as an important source of model uncertainty. In this study, to understand how τE influences terrestrial carbon storage prediction in diagnostic models, we introduced a model decomposition scheme in the Boreal Ecosystem Productivity Simulator (BEPS) and then compared it with a prognostic model. The result showed that τE ranged from 32.7 to 158.2 years. The baseline residence time (τ'E) was stable for each biome, ranging from 12 to 53.7 years for forest biomes and 4.2 to 5.3 years for non-forest biomes. The spatiotemporal variations in τE were mainly determined by the environmental scalar (ξ). By comparing models, we found that the BEPS uses a more detailed pool construction but rougher parameterization for carbon allocation and decomposition. With respect to ξ comparison, the global difference in the temperature scalar (ξt) averaged 0.045, whereas the moisture scalar (ξw) had a much larger variation, with an average of 0.312. We propose that further evaluations and improvements in τ'E and ξw predictions are essential to reduce the uncertainties in predicting carbon storage by the BEPS and similar diagnostic models.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/srep16155DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4635433PMC
November 2015

P2X7R blockade prevents NLRP3 inflammasome activation and brain injury in a rat model of intracerebral hemorrhage: involvement of peroxynitrite.

J Neuroinflammation 2015 Oct 17;12:190. Epub 2015 Oct 17.

The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.

Background: The NLR family, pyrin domain-containing 3 (NLRP3) inflammasome plays a key role in intracerebral hemorrhage (ICH)-induced inflammatory injury, and the purinergic 2X7 receptor (P2X7R) is upstream of NLRP3 activation. This study aimed to investigate how P2X7R functions in ICH-induced inflammatory injury and how the receptor interacts with the NLRP3 inflammasome.

Methods: Rats were treated with P2X7R small interfering RNA (siRNA) 24 h before undergoing collagenase-induced ICH. A selective P2X7R inhibitor (blue brilliant G, BBG) or a peroxynitrite (ONOO(-)) decomposition catalyst (5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato iron(III) [FeTPPS]) was injected 30 min after ICH. Brain water content, hemorrhagic lesion volume, and neurological deficits were evaluated, and western blot, immunofluorescence, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) were carried out.

Results: Striatal P2X7R and NLRP3 inflammasomes were activated after ICH. Gene silencing of P2X7R suppressed NLRP3 inflammasome activation and interleukin (IL)-1β/IL-18 release and significantly ameliorated brain edema and neurological deficits. Additionally, enhanced NADPH oxidase 2 (NOX2, gp91(phox)) and inducible nitric oxide synthase (iNOS), as well as their cytotoxic product (ONOO(-)) were markedly attenuated by BBG treatment following ICH. This was accompanied by downregulations of the inflammasome components, IL-1β/IL-18 and myeloperoxidase (MPO, a neutrophil marker). Most importantly, inflammasome activation and IL-1β/IL-18 release were significantly inhibited by ONOO(-) decomposition with FeTPPS.

Conclusions: Our findings implicate that P2X7R exacerbated inflammatory progression and brain damage in ICH rats possibly via NLRP3 inflammasome-dependent IL-1β/IL-18 release and neutrophil infiltration. ONOO(-), a potential downstream signaling molecule of P2X7R, may play a critical role in triggering NLRP3 inflammasome activation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12974-015-0409-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609067PMC
October 2015

Developing a reference measurement procedure for free glycerol in human serum by two-step gas chromatography-isotope dilution mass spectrometry.

Clin Biochem 2015 Sep 6;48(13-14):897-903. Epub 2015 Jun 6.

Chemical Metrology Division, Applied Sciences Group, Health Sciences Authority, Singapore.

Background: Free glycerol in human serum is measured in clinical laboratories using enzymatic methods, which can be affected by interferences from biological samples. These methods are not applicable when stable isotopic tracers are used to determine lipid kinetics. Hence, a reference measurement procedure for free glycerol in human serum is needed.

Methods: A reference measurement procedure based on two-step gas chromatography-isotope dilution mass spectrometry (GC-IDMS) was developed for the measurement of free glycerol in human serum. This procedure involved spiking with (13)C3-glycerol, protein precipitation and cation exchange SPE, followed by two-step derivatization with 1-butylboronic acid and N-methyl-N-trimethylsilyltrifluoroacetamide. Tripalmitin certified reference material (CRM) was used as the calibration standard to ensure metrological traceability.

Results: Good precision and accuracy were obtained as demonstrated by relative standard deviation (RSD) of 1.51%-3.33%, with average recoveries over 98%. The relative measurement uncertainty was below 3% with major contributions from the concentration of glycerol calibration solution, choice of ion pair, linear regression, and measurement precision.

Conclusions: With good accuracy and precision, as well as clear metrological traceability, the developed GC-IDMS procedure is useful in producing traceable and accurate measurement of free glycerol in human serum.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinbiochem.2015.05.022DOI Listing
September 2015

Increased activity of Rho kinase contributes to hemoglobin-induced early disruption of the blood-brain barrier in vivo after the occurrence of intracerebral hemorrhage.

Int J Clin Exp Pathol 2014 15;7(11):7844-53. Epub 2014 Oct 15.

Department of Neurosurgery, The Fifth Affiliated Hospital of Southern Medical University Guangzhou 510900, China.

This study is to examine whether the activation of Rho kinase (ROCK) accounts for hemoglobin (Hb)-induced disruption of blood-brain barrier (BBB) after the occurrence of intracerebral hemorrhage. A model of intracerebral injection of Hb was established in rats. Changes in the levels of mRNA of RhoA, ROCK2 and matrix metalloproteinase-9 (MMP-9) were measured using quantitative real-time polymerase chain reaction. Protein expression of RhoA, ROCK2, claudin-5 and MMP-9, as well as ROCK activity, were determined using Western blotting. Immunohistochemical assay was performed to visualize the expression of RhoA, ROCK2, claudin-5 and MMP-9 in endothelial cells. Hb injection produced a significant increase in BBB permeability and water content in the brain. Significant reduction of claudin-5 expression was detected by Western blotting and immunofluorescence in Hb group. The levels of RhoA and ROCK2 were significantly up-regulated from 6 h to 12 h after Hb injection and were concomitant with the increase in ROCK activity. Immunofluorescence double staining showed enhanced p-myosin light chain immunoreactivity but diminished claudin-5 staining in endothelial cells. Significant up-regulation of MMP-9 expression was detected after Hb injection, and statistical analyses further confirmed a positive correlation of MMP-9 expression with ROCK activity. The results showed that ROCK was activated in endothelial cells by Hb. This may account for the early disruption of the BBB via up-regulation of p-myosin light chain expression and aggravation of injuries to TJ proteins. The activation of ROCK may also increase MMP-9 expression, thereby leading to further BBB disruption.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270524PMC
September 2015

Determination of total thyroxine in human serum by hollow fiber liquid-phase microextraction and liquid chromatography-tandem mass spectrometry.

Talanta 2014 Aug 29;126:163-9. Epub 2014 Mar 29.

Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore. Electronic address:

Determination of total thyroxine in human serum using hollow fiber liquid-phase microextraction (HF-LPME) has been accomplished for the first time. HF-LPME serves as an inexpensive sample pretreatment and the cleanup method that is nearly solvent-free. Thyroxine was extracted through a water immiscible organic solvent immobilized in the wall pores of a polypropylene hollow fiber into 20μl of an aqueous acceptor phase inside the lumen of the hollow fiber. This technique produced extracts that had comparable cleanness with those obtained using solid-phase extraction (SPE). Serum samples with endogenous thyroxine were spiked with isotopically-labeled thyroxine and analyzed by liquid chromatography-tandem mass spectrometry after HF-LPME extraction. Extraction parameters including the organic phase, acid/base concentration of acceptor phase, stirring speed and extraction time were optimized. The calibration range was found to be linear over 1-1000ng/g with the limit of detection (LOD) of 0.3 ng/g. For quantification of total thyroxine in human serum, 6 subsamples were prepared and the results indicated very good precision with a relative standard deviation of <1.3%. The difference from the SPE method was less than 1.2%, with independent t-test showing insignificant bias. Two reference materials of human serum were analyzed, and our obtained values were compared with the reference values. The results showed very good precision with RSD around 0.2% and the deviation from the reference values were -3.1% and -2.1%. The newly developed method is precise, accurate, inexpensive, and environmentally friendly.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.talanta.2014.03.058DOI Listing
August 2014

Blood-brain barrier disruption induced by hemoglobin in vivo: Involvement of up-regulation of nitric oxide synthase and peroxynitrite formation.

Brain Res 2014 Jul 9;1571:25-38. Epub 2014 May 9.

The National Key Clinic Specialty, The Neurosurgery Institute of Guangdong Province, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.

Accumulating evidence has demonstrated that up-regulation of nitric oxide synthase (NOS) and subsequent peroxynitrite (ONOO(-)) formation exert a devastating effect on the damage of BBB in multiple diseases. However, considerably less attention has been focused on the role of NOS/ONOO(-) in BBB disruption after intracerebral hemorrhage (ICH). Using an experimental stroke model by injecting hemoglobin (Hb) into the caudate nucleus of male Sprague Dawley rats, we explored the role of NOS/ONOO(-) in BBB disruption after ICH. Brain edema content, behavioral changes, alterations of TJ proteins (claudin-5 and ZO-1), expression of neuronal NOS (nNOS), inducible NOS (iNOS) and endothelial NOS (eNOS), formation of 3-nitrotyrosine (3-NT), as well as NO production were investigated. Hb in the rat brain led to a significant brain edema production and neurological deficits. Overexpressed NOS was concomitant with large quantities of 3-NT formation. Moreover, sites of enhanced nNOS, iNOS, eNOS and 3-NT immunoreactivity were colocalized with diminished or discontinuous ZO-1 and/or claudin-5 staining as evidenced by Western blot and immunofluorescence, indicating the involvement of NOS and ONOO(-) in the BBB disruption. Meaningfully, levels of 3-NT in serum, which had a similar tendency with that of in brain tissues (r=0.934, P<0.001), had a marked correlation with brain edema content (r=0.782, P<0.001) and neurological deficits (r=0.851, P<0.001). We concluded that ONOO(-) formation by the upregulation of NOS may play a central role in promoting the BBB damage following ICH. Moreover, ONOO(-) may be a promising biomarker for the judgment or prediction of brain injury and clinical prognosis after ICH.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.brainres.2014.04.042DOI Listing
July 2014

An improved reference measurement procedure for triglycerides and total glycerides in human serum by isotope dilution gas chromatography-mass spectrometry.

Clin Chim Acta 2014 Jan;428:20-5

Background: Triglycerides are widely tested in clinical laboratories using enzymatic methods for lipid profiling. As enzymatic methods can be affected by interferences from biological samples, this together with the non-specific nature of triglycerides measurement makes it necessary to verify the accuracy of the test results with a reference measurement procedure. Several such measurement procedures had been published. These procedures generally involved lengthy and laborious sample preparation steps. In this paper, an improved reference measurement procedure for triglycerides and total glycerides was reported which simplifies the sample preparation steps and greatly shortens the time taken.

Methods: The procedure was based on isotope dilution gas chromatography-mass spectrometry (IDGC-MS)with tripalmitin as the calibration standard. Serum samples were first spiked with isotope-labeled tripalmitin. For the measurement of triglycerides, the serum samples were subjected to lipid extraction followed by separation of triglycerides from diglycerides and monoglycerides. Triglycerides were then hydrolyzed to glycerol, derivatized and injected into the GC–MS for quantification. For the measurement of total glycerides, the serum samples were hydrolyzed directly and derivatized before injection into the GC-MS for quantification.

Results: All measurement results showed good precision with CV <1%. A certified reference material (CRM) of lipids in frozen human serum was used to verify the accuracy of the measurement. The obtained values for both triglycerides and total glycerides were well within the certified ranges of the CRM, with deviation <0.4% from the certified values. The relative expanded uncertainties were also comparable with the uncertainties associated with the certified values of the CRM. The validated procedure was used in an External Quality Assessment (EQA) Program organized by our laboratory to establish the assigned values for triglycerides and total glycerides.
View Article and Find Full Text PDF

Download full-text PDF

Source
January 2014

Assessing the spatiotemporal variation in distribution, extent and NPP of terrestrial ecosystems in response to climate change from 1911 to 2000.

PLoS One 2013 25;8(11):e80394. Epub 2013 Nov 25.

Global Change Research Institute, School of Life Science, Nanjing University, Nanjing,Jiangsu, P. R. China.

To assess the variation in distribution, extent, and NPP of global natural vegetation in response to climate change in the period 1911-2000 and to provide a feasible method for climate change research in regions where historical data is difficult to obtain. In this research, variations in spatiotemporal distributions of global potential natural vegetation (PNV) from 1911 to 2000 were analyzed with the comprehensive sequential classification system (CSCS) and net primary production (NPP) of different ecosystems was evaluated with the synthetic model to determine the effect of climate change on the terrestrial ecosystems. The results showed that consistently rising global temperature and altered precipitation patterns had exerted strong influence on spatiotemporal distribution and productivities of terrestrial ecosystems, especially in the mid/high latitudes. Ecosystems in temperate zones expanded and desert area decreased as a consequence of climate variations. The vegetation that decreased the most was cold desert (18.79%), while the maximum increase (10.31%) was recorded in savanna. Additionally, the area of tundra and alpine steppe reduced significantly (5.43%) and were forced northward due to significant ascending temperature in the northern hemisphere. The global terrestrial ecosystems productivities increased by 2.09%, most of which was attributed to savanna (6.04%), tropical forest (0.99%), and temperate forest (5.49%). Most NPP losses were found in cold desert (27.33%). NPP increases displayed a latitudinal distribution. The NPP of tropical zones amounted to more than a half of total NPP, with an estimated increase of 1.32%. The increase in northern temperate zone was the second highest with 3.55%. Global NPP showed a significant positive correlation with mean annual precipitation in comparison with mean annual temperature and biological temperature. In general, effects of climate change on terrestrial ecosystems were deep and profound in 1911-2000, especially in the latter half of the period.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0080394PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3840029PMC
January 2015

The anatomical and clinical details of the pterygoid canal: a three-dimensional reconstructive virtual anatomic evaluation based on CT.

Surg Radiol Anat 2014 Mar 4;36(2):181-8. Epub 2013 Jul 4.

The National Key Clinic Specialty, Department of Neurosurgery, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.

Purpose: To delineate the pterygoid canal (PC) configuration and its position in relation to surrounding important anatomical landmarks using three-dimensional reconstructive technology based on CT for the Chinese.

Methods: The computerized tomography arteriography (CTA) data of 137 patients were retrospectively evaluated using neuroimaging three-dimensional reconstructive software. The morphological parameters of the PC as well as the spatial relationship and distance between the PC relative to internal carotid artery (ICA) and the foramen rotundum were evaluated.

Results: 83.9% of the PC can be identified by our neuroimaging three-dimensional reconstructive software. The mean distance from the PC to the ICA was 2.6 ± 1.2 mm. The mean distance between medial aspects of bilateral ICA was 19.6 ± 2.7 mm. The distal vertical and horizontal distances between the PC and foramen rotundum were 5.2 ± 3.2 and 6.1 ± 2.8 mm, respectively. All the proximal end of the PC were inferior-lateral to the ICA. The PC mainly (92.9%) ran posteriorly with a medial to lateral direction. The distance from the PC to ICA was positively correlated with the distance between bilateral ICA and the distal diameter of the PC. The vertical distance between the PC and foramen rotundum was positively correlated with the length of the PC and the horizontal distance between the PC and foramen rotundum.

Conclusions: Understanding the configuration and spatial relationship of the PC may be helpful to improve the accuracy and safety of operation during the expanded transnasal endoscopic approaches to skull base. The three-dimensional reconstructive virtual anatomic technology may be a useful tool to delineate the PC configuration and its position to surrounding important anatomical landmarks.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00276-013-1161-xDOI Listing
March 2014
-->