Publications by authors named "Weichao Guo"

13 Publications

  • Page 1 of 1

Prediction of finger kinematics from discharge timings of motor units: implications for intuitive control of myoelectric prostheses.

J Neural Eng 2019 04 29;16(2):026005. Epub 2018 Nov 29.

State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China.

Objective: The aim of the study was to characterize the accuracy in the identification of motor unit discharges during natural movements using high-density electromyography (EMG) signals and to investigate their correlation with finger kinematics.

Approach: High-density EMG signals of forearm muscles and finger joint angles were recorded concurrently during hand movements of ten able-bodied subjects. EMG signals were decomposed into motor unit spike trains (MUSTs) with a blind-source separation method. The first principle component (FPC) of the low-pass filtered MUST was correlated with finger joint angles.

Main Results: On average, [Formula: see text] motor units were identified during each individual finger task with an estimated decomposition accuracy [Formula: see text]85%. The FPC extracted from discharge rates was strongly associated to the joint angles ([Formula: see text]), and preceded the joint angles on average by [Formula: see text] ms. Moreover, the FPC outperformed two time-domain features (the EMG envelop and the root mean square of EMG) in estimating joint angles.

Significance: These results indicated the possibility of identifying individual motor unit behavior in dynamic natural contractions. Moreover, the strong association between motor unit discharge behaviors and kinematics proves the potential of the approach for the simultaneous and proportional control of prostheses.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1741-2552/aaf4c3DOI Listing
April 2019

Uneven winter snow influence on tree growth across temperate China.

Glob Chang Biol 2019 01 6;25(1):144-154. Epub 2018 Nov 6.

Faculty of Geographical Science, Beijing Normal University, Beijing, China.

Winter snow is an important driver of tree growth in regions where growing-season precipitation is limited. However, observational evidence of this influence at larger spatial scales and across diverse bioclimatic regions is lacking. Here, we investigated the interannual effects of winter (here defined as previous October to current February) snow depth on tree growth across temperate China over the period of 1961-2015, using a regional network of tree ring records, in situ daily snow depth observations, and gridded climate data. We report uneven effects of winter snow depth on subsequent growing-season tree growth across temperate China. There shows little effect on tree growth in drier regions that we attribute mainly to limited snow accumulation during winter. By contrast, winter snow exerts important positive influence on tree growth in stands with high winter snow accumulation (e.g., in parts of cold arid regions). The magnitude of this effect depends on the proportion of winter snow to pre-growing-season (previous October to current April) precipitation. We further observed that tree growth in drier regions tends to be increasingly limited by warmer growing-season temperature and early growing-season water availability. No compensatory effect of winter snow on the intensifying drought limitation of tree growth was observed across temperate China. Our findings point toward an increase in drought vulnerability of temperate forests in a warming climate.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/gcb.14464DOI Listing
January 2019

GM-CSF overexpression after influenza a virus infection prevents mortality and moderates M1-like airway monocyte/macrophage polarization.

Respir Res 2018 01 5;19(1). Epub 2018 Jan 5.

Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, USA.

Background: Influenza A viruses cause life-threatening pneumonia and lung injury in the lower respiratory tract. Application of high GM-CSF levels prior to infection has been shown to reduce morbidity and mortality from pathogenic influenza infection in mice, but the mechanisms of protection and treatment efficacy have not been established.

Methods: Mice were infected intranasally with influenza A virus (PR8 strain). Supra-physiologic levels of GM-CSF were induced in the airways using the double transgenic GM-CSF (DTGM) or littermate control mice starting on 3 days post-infection (dpi). Assessment of respiratory mechanical parameters was performed using the flexiVent rodent ventilator. RNA sequence analysis was performed on FACS-sorted airway macrophage subsets at 8 dpi.

Results: Supra-physiologic levels of GM-CSF conferred a survival benefit, arrested the deterioration of lung mechanics, and reduced the abundance of protein exudates in bronchoalveolar (BAL) fluid to near baseline levels. Transcriptome analysis, and subsequent validation ELISA assays, revealed that excess GM-CSF re-directs macrophages from an "M1-like" to a more "M2-like" activation state as revealed by alterations in the ratios of CXCL9 and CCL17 in BAL fluid, respectively. Ingenuity pathway analysis predicted that GM-CSF surplus during IAV infection elicits expression of anti-inflammatory mediators and moderates M1 macrophage pro-inflammatory signaling by Type II interferon (IFN-γ).

Conclusions: Our data indicate that application of high levels of GM-CSF in the lung after influenza A virus infection alters pathogenic "M1-like" macrophage inflammation. These results indicate a possible therapeutic strategy for respiratory virus-associated pneumonia and acute lung injury.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12931-017-0708-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5756339PMC
January 2018

Differentiating drought legacy effects on vegetation growth over the temperate Northern Hemisphere.

Glob Chang Biol 2018 Jan 23;24(1):504-516. Epub 2017 Oct 23.

State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, China.

In view of future changes in climate, it is important to better understand how different plant functional groups (PFGs) respond to warmer and drier conditions, particularly in temperate regions where an increase in both the frequency and severity of drought is expected. The patterns and mechanisms of immediate and delayed impacts of extreme drought on vegetation growth remain poorly quantified. Using satellite measurements of vegetation greenness, in-situ tree-ring records, eddy-covariance CO and water flux measurements, and meta-analyses of source water of plant use among PFGs, we show that drought legacy effects on vegetation growth differ markedly between forests, shrubs and grass across diverse bioclimatic conditions over the temperate Northern Hemisphere. Deep-rooted forests exhibit a drought legacy response with reduced growth during up to 4 years after an extreme drought, whereas shrubs and grass have drought legacy effects of approximately 2 years and 1 year, respectively. Statistical analyses partly attribute the differences in drought legacy effects among PFGs to plant eco-hydrological properties (related to traits), including plant water use and hydraulic responses. These results can be used to improve the representation of drought response of different PFGs in land surface models, and assess their biogeochemical and biophysical feedbacks in response to a warmer and drier climate.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/gcb.13920DOI Listing
January 2018

TGF-β stimulates HDAC4 nucleus-to-cytoplasm translocation and NADPH oxidase 4-derived reactive oxygen species in normal human lung fibroblasts.

Am J Physiol Lung Cell Mol Physiol 2017 06 23;312(6):L936-L944. Epub 2017 Mar 23.

Department of Medicine, Section of Pulmonary Diseases, Critical Care and Environmental Medicine, Tulane University Health Science Center, New Orleans, Louisiana;

Myofibroblasts are important mediators of fibrogenesis; thus blocking fibroblast-to-myofibroblast differentiation (FMD) may be an effective strategy to treat pulmonary fibrosis (PF). Previously, we reported that histone deacetylase 4 (HDAC4) activity is necessary for transforming growth factor-β (TGF-β)-induced human lung FMD. Here, we show that TGF-β increases NADPH oxidase 4 (NOX4) mRNA and protein expression in normal human lung fibroblasts (NHLFs) and causes nuclear export of HDAC4. Application of the NOX family inhibitor diphenyleneiodonium chloride reduces TGF-β-induced HDAC4 nuclear export, expression of the myofibroblast marker α-smooth muscle actin (α-SMA), and α-SMA fiber formation. Inhibition of HDAC4 nucleus-to-cytoplasm translocation using leptomycin B (LMB) had little effect on α-SMA expression but blocked α-SMA fiber formation. A coimmunoprecipitation assay showed that HDAC4 associates with α-SMA. Moreover, LMB abolishes TGF-β-induced α-SMA fiber formation and cell contraction. Relevant to human pulmonary fibrosis, idiopathic PF specimens showed significantly higher NOX4 RNA expression and scant HDAC4 staining within nuclei of fibroblast foci myofibroblasts. Taken together, these results indicate that reactive oxygen species promote TGF-β-mediated myofibroblast differentiation and HDAC4 nuclear export. The physical association of HDAC4 with α-SMA suggests that HDAC4 has a role in regulating the α-SMA cytoskeleton arrangement.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/ajplung.00256.2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5495947PMC
June 2017

A portable multi-channel wireless NIRS device for muscle activity real-time monitoring.

Annu Int Conf IEEE Eng Med Biol Soc 2014 ;2014:3719-22

Near-infrared spectroscopy (NIRS) is a relative new technology in monitoring muscle oxygenation and hemo-dynamics. This paper presents a portable multi-channel wireless NIRS device for real-time monitoring of muscle activity. The NIRS sensor is designed miniaturized and modularized, to make multi-site monitoring convenient. Wireless communication is applied to data transmission avoiding of cumbersome wires and the whole system is highly integrated. Special care is taken to eliminate motion artifact when designing the NIRS sensor and attaching it to human skin. Besides, the system is designed with high sampling rate so as to monitor rapid oxygenation changes during muscle activities. Dark noise and long-term drift tests have been carried out, and the result indicates the device has a good performance of accuracy and stability. In vivo experiments including arterial occlusion and isometric voluntary forearm muscle contraction were performed, demonstrating the system has the ability to monitor muscle oxygenation parameters effectively even in exercise.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1109/EMBC.2014.6944431DOI Listing
November 2015

Identification of two forms of the Eso1 protein in Schizosaccharomyces pombe.

Cell Biol Int 2014 May 29;38(5):682-8. Epub 2014 Jan 29.

Basic Medical College, Jilin University, Jilin, China.

In Schizosaccharomyces pombe, Eso1p is a protein fusion. Two-thirds of its N-terminus is conserved to budding yeast Rad30, which functions in error-free replication of UV-damaged DNA. A third of the C-terminus is highly conserved to budding yeast Eco1, a lysine acetyltransferase, which is essential for the establishment of cohesion. Both Rad30p and Eco1p need to be finely tuned in budding yeast. Given the distinct function existed in Rad30p and Eco1p, it is enigmatic how the Eso1p, the protein fusion regulated in S. pombe, works. We have identified two forms of the Eso1 protein by Western blot, and detected the Eco1-homology fragment by M/S analysis following TAP purification of Eso1 protein. The result raises the possibility that Eso1 might be processed in vivo to release the Eco1-homology fragment, which allows the independent regulation of Rad30-homology and Eco1-homology fragments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/cbin.10230DOI Listing
May 2014

Amino-functionalized macroporous silica for efficient tryptic digestion in acidic solutions.

Proteomics 2013 Nov 9;13(21):3117-23. Epub 2013 Oct 9.

Department of Chemistry, Institute of Biomedical Sciences and State Key Lab of Molecular Engineering of Polymers, Fudan University, Shanghai, China.

Amino-functionalized macroporous silica foam (NH2 -MOSF) has been developed as a host reactor to realize highly efficient proteolysis in acidic solutions where normal tryptic reactions cannot occur. The digestion protocol consists simply of adding the functionalized NH2 -MOSF into the protein and trypsin solutions without altering the bulk pH or preloading the enzymes on the materials. With this protocol, digestion of sample fractions from LC can be efficiently realized in the acidic solutions directly. Digestion of a protein fraction extracted from rat liver tissue after LC separation was performed to illustrate this principle, where 103 proteins were successfully identified at pH 3 after 1.5 h of tryptic digestion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/pmic.201300108DOI Listing
November 2013

A genetic screen to discover pathways affecting cohesin function in Schizosaccharomyces pombe identifies chromatin effectors.

G3 (Bethesda) 2012 Oct 1;2(10):1161-8. Epub 2012 Oct 1.

Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.

Cohesion, the force that holds sister chromatids together from the time of DNA replication until separation at the metaphase to anaphase transition, is mediated by the cohesin complex. This complex is also involved in DNA damage repair, chromosomes condensation, and gene regulation. To learn more about the cellular functions of cohesin, we conducted a genetic screen in Schizosaccharomyces pombe with two different cohesin mutants (eso1-G799D and mis4-242). We found synthetic negative interactions with deletions of genes involved in DNA replication and heterochromatin formation. We also found a few gene deletions that rescued the growth of eso1-G799D at the nonpermissive temperature, and these genes partially rescue the lagging chromosome phenotype. These genes are all chromatin effectors. Overall, our screen revealed an intimate association between cohesin and chromatin.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1534/g3.112.003327DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3464108PMC
October 2012

Characterization of efficient proteolysis by trypsin loaded macroporous silica.

Mol Biosyst 2011 Oct 29;7(10):2890-8. Epub 2011 Jul 29.

Department of Chemistry, Fudan University, Shanghai, People's Republic of China.

Tryptic digestion of proteins in trypsin loaded porous silica has been shown to be highly efficient. Enzymatic silica-reactors were prepared by immobilizing trypsin into macroporous ordered siliceous foam (MOSF) and into mesoporous SBA-15 silica which has a smaller pore size. The tryptic products from the silica reactors were analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), and a higher proteolysis efficiency was obtained with MOSF. These results can be well interpreted by a sequential digestion model taking into account the confinement and concentration enrichment of both the substrates and enzymes within the silica pores. Proteins at low concentrations and proteins in urea and surfactant solutions were also successfully digested with the MOSF-based reactor and identified by MS. Considering that the immobilized trypsin could retain its enzymatic activity for weeks, this MOSF reactor provides many advantages compared to free enzyme proteolysis. As a proof-of-concept, the digest of a real complex sample extracted from the cytoplasm of mouse liver tissue using trypsin loaded MOSF yielded better results than the typical in-solution protocol.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c1mb05140gDOI Listing
October 2011

Post-transcriptional up-regulation of miR-21 by type I collagen.

Mol Carcinog 2011 Jul 11;50(7):563-70. Epub 2011 Feb 11.

Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University, Hunan, China.

Composition of extracellular matrix (ECM) is crucial to the establishment and maintenance of epithelial apical-basolateral polarity. Increased ECM rigidity caused by deposition of fibrillar collagen, for example, collagen type I (Col-1), promotes loss of epithelial polarity and tumor progression. microRNAs are small non-coding RNAs that regulate gene expression and fundamental cellular processes. The current study explored a link between microRNAs and Col-1 using organotypic three-dimensional culture in which epithelial cells are embedded within Matrigel, a mimic of basement membrane matrix (Matrigel 3-D). Matrigel 3-D culture of A549, MCF-7, and mK-ras-LE cells (lung and mammary epithelial cell lines) gave rise to acinus, an in vitro equivalent of apical-basolateral polarity that consists of a polarized monolayer of epithelial cells facing a central lumen. Supplementation of Col-1 disrupted acinus. Moreover, Col-1 up-regulated the expression of miR-21, a well-documented oncogenic microRNA, via a post-transcriptional mechanism. Similar post-transcriptional up-regulation of miR-21 correlated with deposition of Col-1 in a murine model of lung fibrogenesis. In summary, our findings link altered ECM composition/rigidity and the expression of oncogenic microRNAs. The current study also suggests a novel post-transcriptional mechanism for regulation of miR-21 expression at maturation from pre-miR-21 to mature miR-21.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/mc.20742DOI Listing
July 2011

Pharmacological inhibition of HDAC6 attenuates endothelial barrier dysfunction induced by thrombin.

Biochem Biophys Res Commun 2011 May 21;408(4):630-4. Epub 2011 Apr 21.

Department of Medicine, Tulane Medical School, New Orleans, LA, USA.

Background: Endothelial barrier dysfunction (EBD) involves microtubule disassembly and enhanced cell contractility. Histone deacetylase 6 (HDAC6) deacetylates α-tubulin, and thereby destabilizes microtubules. This study investigates a role for HDAC6 in EBD.

Methods: EBD was induced with thrombin±HDAC6 inhibitors (tubacin and MC1575), and assessed by transendothelial electrical resistance (TEER). Markers for microtubule disassembly (α-tubulin and acetylated α-tubulin) and contraction (phosphorylated myosin light chain 2, P-MLC2) were measured using immunoblots and immunofluorescence.

Results And Conclusion: Thrombin induced a ∼50% decrease in TEER that was abrogated by the HDAC6 inhibitors. Moreover, inhibition of HDAC6 diminished edema in the lung injured by lipopolysaccharide. Lastly, inhibition of HDAC6 attenuated thrombin-induced microtubule disassembly and P-MLC2. Our results suggest that HDAC6 can be targeted to limit EBD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbrc.2011.04.075DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3100403PMC
May 2011

Abrogation of TGF-beta1-induced fibroblast-myofibroblast differentiation by histone deacetylase inhibition.

Am J Physiol Lung Cell Mol Physiol 2009 Nov 21;297(5):L864-70. Epub 2009 Aug 21.

Biomedical Sciences Program, 1430 Tulane Ave. SL-9, Tulane Medical School, New Orleans, LA 70112, USA.

Idiopathic pulmonary fibrosis (IPF) is a devastating disease with no known effective pharmacological therapy. The fibroblastic foci of IPF contain activated myofibroblasts that are the major synthesizers of type I collagen. Transforming growth factor (TGF)-beta1 promotes differentiation of fibroblasts into myofibroblasts in vitro and in vivo. In the current study, we investigated the molecular link between TGF-beta1-mediated myofibroblast differentiation and histone deacetylase (HDAC) activity. Treatment of normal human lung fibroblasts (NHLFs) with the pan-HDAC inhibitor trichostatin A (TSA) inhibited TGF-beta1-mediated alpha-smooth muscle actin (alpha-SMA) and alpha1 type I collagen mRNA induction. TSA also blocked the TGF-beta1-driven contractile response in NHLFs. The inhibition of alpha-SMA expression by TSA was associated with reduced phosphorylation of Akt, and a pharmacological inhibitor of Akt blocked TGF-beta1-mediated alpha-SMA induction in a dose-dependent manner. HDAC4 knockdown was effective in inhibiting TGF-beta1-stimulated alpha-SMA expression as well as the phosphorylation of Akt. Moreover, the inhibitors of protein phosphatase 2A and 1 (PP2A and PP1) rescued the TGF-beta1-mediated alpha-SMA induction from the inhibitory effect of TSA. Together, these data demonstrate that the differentiation of NHLFs to myofibroblasts is HDAC4 dependent and requires phosphorylation of Akt.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/ajplung.00128.2009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2777501PMC
November 2009