PLA Fourth Military Medical University | Date: 2015-05-29
The present invention discloses a cellulose derivative shown as formula (I), which is obtained as follows: the hydroxyl at position 6 of microcrystalline cellulose is protected with triphenylchloromethane, and then reacted with acyl chloride or isocyanate. After the protection of the hydroxyl at positions 2 and 3 of microcrystalline cellulose, triphenylmethyl is removed under acidic conditions to expose the hydroxyl at position 6. Finally, the hydroxyl at position 6 is chiral derivatized with amino acid acyl chloride or polypeptide acyl chloride, to obtain a micro chiral regulation cellulose derivative. The micro chiral regulation cellulose derivative thus obtained is coated onto the surface of a silica gel support, to form a chiral stationary phase, which is filled in a stainless steel column to form a chiral column for the separation of various different types of chiral compounds. The preparation method of the present invention is not only efficient and convenient, but also safe and reliable. The chiral column thus formed has stable performance, high separation efficiency, and is suitable for large scale production.
Zhang H.-M.,PLA Fourth Military Medical University |
Zhang Y.,University of Texas Health Science Center at San Antonio
Journal of Pineal Research | Year: 2014
Melatonin (N-acetyl-5-methoxytryptamine), an indoleamine produced in many organs including the pineal gland, was initially characterized as a hormone primarily involved in circadian regulation of physiological and neuroendocrine function. Subsequent studies found that melatonin and its metabolic derivatives possess strong free radical scavenging properties. These metabolites are potent antioxidants against both ROS (reactive oxygen species) and RNS (reactive nitrogen species). The mechanisms by which melatonin and its metabolites protect against free radicals and oxidative stress include direct scavenging of radicals and radical products, induction of the expression of antioxidant enzymes, reduction of the activation of pro-oxidant enzymes, and maintenance of mitochondrial homeostasis. In both in vitro and in vivo studies, melatonin has been shown to reduce oxidative damage to lipids, proteins and DNA under a very wide set of conditions where toxic derivatives of oxygen are known to be produced. Although the vast majority of studies proved the antioxidant capacity of melatonin and its derivatives, a few studies using cultured cells found that melatonin promoted the generation of ROS at pharmacological concentrations (μm to mm range) in several tumor and nontumor cells; thus, melatonin functioned as a conditional pro-oxidant. Mechanistically, melatonin may stimulate ROS production through its interaction with calmodulin. Also, melatonin may interact with mitochondrial complex III or mitochondrial transition pore to promote ROS production. Whether melatonin functions as a pro-oxidant under in vivo conditions is not well documented; thus, whether the reported in vitro pro-oxidant actions come into play in live organisms remains to be established. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Liu H.,PLA Fourth Military Medical University
PloS one | Year: 2012
In vitro hypoxic preconditioning (HP) of mesenchymal stem cells (MSCs) could ameliorate their viability and tissue repair capabilities after transplantation into the injured tissue through yet undefined mechanisms. There is also experimental evidence that HP enhances the expression of both stromal-derived factor-1 (SDF-1) receptors, CXCR4 and CXCR7, which are involved in migration and survival of MSCs in vitro, but little is known about their role in the in vivo therapeutic effectiveness of MSCs in renal ischemia/reperfusion (I/R) injury. Here, we evaluated the role of SDF-1-CXCR4/CXCR7 pathway in regulating chemotaxis, viability and paracrine actions of HP-MSCs in vitro and in vivo. Compared with normoxic preconditioning (NP), HP not only improved MSC chemotaxis and viability but also stimulated secretion of proangiogenic and mitogenic factors. Importantly, both CXCR4 and CXCR7 were required for the production of paracrine factors by HP-MSCs though the former was only responsible for chemotaxis while the latter was for viability. SDF-1α expression was upregulated in postischemic kidneys. After 24 h systemical administration following I/R, HP-MSCs but not NP-MSCs were selectively recruited to ischemic kidneys and this improved recruitment was abolished by neutralization of CXCR4, but not CXCR7. Furthermore, the increased recruitment of HP-MSCs was associated with enhanced functional recovery, accelerated mitogenic response, and reduced apoptotic cell death. In addition, neutralization of either CXCR4 or CXCR7 impaired the improved therapeutic potential of HP-MSCs. These results advance our knowledge about SDF-1-CXCR4/CXCR7 axis as an attractive target pathway for improving the beneficial effects of MSC-based therapies for renal I/R.
Zhang L.-F.,PLA Fourth Military Medical University
European Journal of Applied Physiology | Year: 2013
Evidence from recent ground and spaceflight studies with animals and humans supports the notion that microgravity-induced vascular remodeling contributes to postflight orthostatic intolerance. In the vascular beds of lower body, such as in splanchnic and lower limb circulation, resistance vessels would undergo hypotrophy and decrement in myogenic tone and vasoreactivity. Thus, despite the concurrent sympathetic activation, the increase in peripheral vascular resistance would still be compromised while astronauts were re-exposed to Earth's 1-G gravity, since ∼75 % of the total vascular conductance lies below the heart. On the contrary, cerebral arteries would undergo hypertrophy and vasoreactivity enhancement due to adaptation to cerebral hypertension, which protects the down-stream microcirculation in the brain during spaceflight. However, the enhanced vasoreactivity of cerebral vessels might also aggravate postflight orthostatic intolerance, particularly after long-duration spaceflight. Animal studies have indicated that the underlying mechanisms may involve ion-channel remodeling in vascular smooth muscle cells and vascular NO-NOS and local renin-angiotensin system (L-RAS). Furthermore, vascular remodeling and associated ion-channel and L-RAS changes can be prevented by a countermeasure of daily short-duration restoring to normal standing posture. These findings substantiate in general the hypothesis that redistribution of transmural pressure along the arterial vasculature due to the removal of gravity might be the primary factor that initiates vascular remodeling in microgravity, and daily short-duration restoring its normal distribution by intermittent artificial gravity (IAG) can effectively prevent the vascular adaptation and hence postflight cardiovascular deconditioning. IAG might also be beneficial in maintaining vascular health during future long-duration space flight. © 2013 Springer-Verlag Berlin Heidelberg.
Li H.,PLA Fourth Military Medical University
PloS one | Year: 2012
Traditional Chinese medicinal herbs Cortex Moutan and Radix Salviae Milthiorrhizaeare are prescribed together for their putative cardioprotective effects in clinical practice. However, the rationale of the combined use remains unclear. The present study was designed to investigate the cardioprotective effects of paeonol and danshensu (representative active ingredient of Cortex Moutan and Radix Salviae Milthiorrhizae, respectively) on isoproterenol-induced myocardial infarction in rats and its underlying mechanisms. Paeonol (80 mg kg(-1)) and danshensu (160 mg kg(-1)) were administered orally to Sprague Dawley rats in individual or in combination for 21 days. At the end of this period, rats were administered isoproterenol (85 mg kg(-1)) subcutaneously to induce myocardial injury. After induction, rats were anaesthetized with pentobarbital sodium (35 mg kg(-1)) to record electrocardiogram, then sacrificed and biochemical assays of the heart tissues were performed. Induction of rats with isoproterenol resulted in a marked (P<0.001) elevation in ST-segment, infarct size, level of serum marker enzymes (CK-MB, LDH, AST and ALT), cTnI, TBARS, protein expression of Bax and Caspase-3 and a significant decrease in the activities of endogenous antioxidants (SOD, CAT, GPx, GR, and GST) and protein expression of Bcl-2. Pretreatment with paeonol and danshensu combination showed a significant (P<0.001) decrease in ST-segment elevation, infarct size, cTnI, TBARS, protein expression of Bax and Caspase-3 and a significant increase in the activities of endogenous antioxidants and protein expression of Bcl-2 and Nrf2 when compared with individual treated groups. This study demonstrates the cardioprotective effect of paeonol and danshensu combination on isoproterenol-induced myocardial infarction in rats. The mechanism might be associated with the enhancement of antioxidant defense system through activating of Nrf2 signaling and anti-apoptosis through regulating Bax, Bcl-2 and Caspase-3. It could provide experimental evidence to support the rationality of combinatorial use of traditional Chinese medicine in clinical practice.
Zhao X.,PLA Fourth Military Medical University
Cell Death and Differentiation | Year: 2014
Dysregulation of transcription factors (TFs) is associated with tumor progression, but little is known about TF expression patterns in the context of gastric cancer (GC) metastasis. Using array-based profile analysis, we found that 22 TFs showed differential activities between GC cell lines with low- and high-metastatic potential. Of this group of TFs, serum response factor (SRF) was significantly upregulated in metastatic GC cells. SRF expression was frequently elevated in a panel of metastatic GC cells and tissues, and high-level expression of SRF was significantly associated with a more aggressive phenotype and poor prognosis in patients with GC. In GC cell lines, overexpression of SRF potently promoted cell migration and invasion in vitro as well as the formation of intrahepatic and pulmonary metastases in vivo, whereas loss of SRF inhibited GC cell invasion and metastasis. We also performed a microRNA microarray to screen for transcriptional targets of SRF and found that SRF transactivates miR-199a-5p and miR-199a-3p by directly binding to their promoters. We further determined that overexpression of miR-199a-5p, but not miR-199a-3p, increased GC cell invasion and metastasis. In contrast, inhibition of miR-199a-5p impaired the metastatic potential of GC cells in vitro and in vivo, and E-cadherin was identified as a direct and functional target of miR-199a-5p in GC cells. Specifically, our results showed that SRF promotes GC metastasis and the epithelial to mesenchymal transition (EMT) though miR-199a-5p-mediated downregulation of E-cadherin. The present study thus provides insight into the specific biological behavior of SRF in GC metastasis. As increased activity of the SRF/miR-199a-5p/E-cadherin pathway appears to promote GC cell EMT and metastasis, these regulators may therefore be developed as therapeutic targets or biomarkers for GC progression.Cell Death and Differentiation advance online publication, 1 August 2014; doi:10.1038/cdd.2014.109.
Sun Z.,PLA Fourth Military Medical University
Nanoscale | Year: 2013
Herein we report the design and synthesis of multifunctional VEGF-loaded IR800-conjugated graphene oxide (GO-IR800-VEGF) for multi-modality imaging-monitored therapeutic angiogenesis of ischemic muscle. The as-prepared GO-IR800-VEGF positively targets VEGF receptors, maintains an elevated level of VEGF in ischemic tissues for a prolonged time, and finally leads to remarkable therapeutic angiogenesis of ischemic muscle. Although more efforts are required to further understand the in vivo behaviors and the long-term toxicology of GO, our work demonstrates the success of using GO for efficient VEGF delivery in vivo by intravenous administration and suggests the great promise of using graphene oxide in theranostic applications for treating ischemic disease.
Ping Z.,PLA Fourth Military Medical University
Autoimmunity Reviews | Year: 2014
Idiopathic pulmonary fibrosis (IPF) is a progressive fibrosing disease with disappointing survival rate, and uneffective therapeutic progress has been made in the last few years, forcing the urgent need to improve research to this disease. The commonly accepted pathogenic hypothesis of IPF is the trigger from continuous alveolar epithelium microinjuries and in the following series events, many signaling pathways were reported to lead to abnormal tissue repair and lung structure derangement in IPF, such as TGF-β, wnt, VEGF and PI3K-Akt signaling pathways. Traditional research of IPF related signaling pathway always focus on the independent function of pathway and disease signals, but the crosstalks and interactions among them were rarely valued. In this review, we summarize the signaling pathways which were reported to play important roles in the pathologic changes of IPF and the synergistic effect among those pathways. Next we discuss the application of genomics research and bioinformatics tools on IPF related pathway analysis, and give a systems biology perspective by integrating multi-level disease related data. The novel prospective of pathway analysis could tease out the complex pathway interaction profiles of IPF, and is powerful to detect IPF related biomarkers for early diagnose and potential therapeutic targets. © 2014 Elsevier B.V.
Chen F.M.,PLA Fourth Military Medical University
Tissue engineering. Part B, Reviews | Year: 2010
The management of periodontal tissue defects that result from periodontitis represents a medical and socioeconomic challenge. Concerted efforts have been and still are being made to accelerate and augment periodontal tissue and bone regeneration, including a range of regenerative surgical procedures, the development of a variety of grafting materials, and the use of recombinant growth factors. More recently, tissue-engineering strategies, including new cell- and/or matrix-based dimensions, are also being developed, analyzed, and employed for periodontal regenerative therapies. Tissue engineering in periodontology applies the principles of engineering and life sciences toward the development of biological techniques that can restore lost alveolar bone, periodontal ligament, and root cementum. It is based on an understanding of the role of periodontal formation and aims to grow new functional tissues rather than to build new replacements of periodontium. Although tissue engineering has merged to create more opportunities for predictable and optimal periodontal tissue regeneration, the technique and design for preclinical and clinical studies remain in their early stages. To date, the reconstruction of small- to moderate-sized periodontal bone defects using engineered cell-scaffold constructs is technically feasible, and some of the currently developed concepts may represent alternatives for certain ideal clinical scenarios. However, the predictable reconstruction of the normal structure and functionality of a tooth-supporting apparatus remains challenging. This review summarizes current regenerative procedures for periodontal healing and regeneration and explores their progress and difficulties in clinical practice, with particular emphasis placed upon current challenges and future possibilities associated with tissue-engineering strategies in periodontal regenerative medicine.
PLA Fourth Military Medical University | Date: 2014-07-30
An electrical impedance measurement device and method for a portable electrical impedance imaging system adopt a current excitation and voltage measurement principle. An excitation signal is a square wave current signal with constant strength. A response voltage signal on an imaging target passes through circuits such as a buffer amplification circuit, a resistor-capacitor direct current-blocking circuit, and a differential amplification circuit sequentially and is processed into a square signal with suitable amplitude, which is converted into a digital signal by an analog to digital converter at a suitable point of time. The ADC performs data sampling on a measured voltage signal at a high level and a low level of a square wave cycle, to obtain sampling results V_(1) and V_(2), and the difference between the V_(1) and V_(2) is used as a voltage measurement result in this cycle. The average of voltage measurement results in a plurality of cycles is used as a final voltage measurement result. Due to the constant strength of the excitation current signal, the voltage measurement result can reflect electrical impedance information of the imaging target.