徐翔 楊陳麗 趙寶華 陳晶
[摘要] 目的 研究Toll樣受體4(TLR4)和核轉(zhuǎn)錄因子-κB(NF-κB)在局部腦缺血再灌注模型腦組織中表達的變化。方法 選擇36只SD大鼠隨機分為3組,分別為假手術(shù)組(S組)、對照組(C組)和菊酯組(NF-κB抑制劑,CE組),每組12只。建立局部腦缺血再灌注的大鼠模型。采用雙盲法對大鼠神經(jīng)功能缺損評分進行記錄,應(yīng)用氯化三苯基四氮唑(TTC)染色法評估大腦梗死體積,TUNEL染色法標記凋亡細胞,蛋白質(zhì)印跡分析檢測TLR4和NF-κB的表達。結(jié)果 C組和CE組大鼠的神經(jīng)功能缺損評分顯著高于S組(F=16.7~189.7,P<0.01)。TTC染色結(jié)果表明,C組和CE組的腦缺血程度高于S組,CE組的腦梗死體積顯著低于C組(F=271.5,P<0.01)。同時,CE組中TUNEL陽性細胞數(shù)顯著低于C組(F=616.9,P<0.01)。S組大鼠NF-κB和TLR4表達水平均顯著低于C組和CE組(F=279.7、884.8,P<0.01),而其在CE組大鼠表達水平顯著低于C組(P<0.01)。結(jié)論NF-κB和TLR4的高表達可能與腦缺血再灌注損傷具有相關(guān)性。
[關(guān)鍵詞] 腦缺血;再灌注損傷;Toll樣受體4;NF-κB;大鼠,Sprague-Dawley
[中圖分類號] R743.31;R619.9 ?[文獻標志碼] A ?[文章編號] 2096-5532(2020)02-0212-05
doi:10.11712/jms.2096-5532.2020.56.063 [開放科學(資源服務(wù))標識碼(OSID)]
[網(wǎng)絡(luò)出版] http://kns.cnki.net/kcms/detail/37.1517.R.20200417.0914.006.html;2020-04-17 17:04
[ABSTRACT] Objective To study the changes in the expression of Toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) in the brain tissue of focal cerebral ischemia-reperfusion model. ?Methods A total of 36 Sprague-Dawley rats were randomly divided into sham operation group (group S), control group (group C), and chrysanthemum ester group (NF-κB inhibitor, group CE), with 12 rats in each group. A rat model of focal cerebral ischemia-reperfusion was established. The double-blind me-thod was used to record the neurological deficit score of rats. The 2,3,5-triphenyltetrazolium chloride (TTC) staining of the brain slices was performed to evaluate the cerebral infarct volume. TUNEL staining was carried out to label the apoptotic cells. Western blotting analysis was used to measure the expression of TLR4 and NF-κB. ?Results Groups C and CE had significantly higher neurological deficit scores than group S (F=16.7-189.7,P<0.01). The TTC staining results showed that groups C and CE had higher degrees of cerebral ischemia than group S, but the cerebral infarct volume in group CE was significantly lower than that in group C (F=271.5,P<0.01). In addition, group CE had a significantly lower number of TUNEL positive cells than group C (F=616.9,P<0.01). The Western blotting results showed that group S had significantly lower expression levels of NF-κB and TLR4 than groups C and CE (F=279.7,884.8;P<0.01), and group CE had significantly lower expression levels of NF-κB and TLR4 than group C (P<0.01). ?Conclusion The increased expression of NF-κB and TLR4 may be related to the cerebral ischemia-reperfusion injury.
[KEY WORDS] brain ischemia; reperfusion injury; Toll-like receptor 4; NF-kappa B; rats, Sprague-Dawley
腦卒中是人類致死的第二大病因,其嚴重影響病人的生活質(zhì)量,并且對家庭和社會造成巨大的經(jīng)濟負擔[1-3]。臨床上,腦卒中分為缺血性卒中和出血性卒中,缺血性卒中占卒中發(fā)病率的80%左右[4-6]。各種原因引起的大腦供血、供氧減少可導致缺血性腦血管病的發(fā)生和組織的壞死,而腦缺血再灌注有時會進一步加重卒中損害和功能紊亂。業(yè)已證實,炎癥與神經(jīng)元細胞死亡和神經(jīng)系統(tǒng)功能紊亂密切相關(guān)。核轉(zhuǎn)錄因子-κB(NF-κB)在炎癥發(fā)生過程中具有關(guān)鍵作用[7]。Toll樣受體(TLR)是一種跨膜受體,而TLR4作為其中一種亞型,主要識別不同的病原相關(guān)分子模式,進而導致炎癥細胞分泌增加,引起全身炎癥反應(yīng)[8-9]。目前,對TLR4/NF-κB信號通路在局部腦缺血再灌注損傷中的作用還不夠明確[10]。本文通過建立大鼠缺血再灌注模型,探討缺血再灌注引起的神經(jīng)系統(tǒng)損傷與TLR4/NF-κB表達的關(guān)系,旨在為明確缺血再灌注損傷機制提供依據(jù)?,F(xiàn)將結(jié)果報告如下。
1 材料和方法
1.1 主要材料
菊酯(NF-κB抑制劑)、水合氯醛(上海阿拉丁生物技術(shù)公司),氯化三苯基四氮唑(TTC,美國Sigma公司),大鼠ELISA試劑盒(ELC)(美國Invitrogen公司,貨號:ML-Elisa-0600),二甲基亞砜(DMSO,美國Sigma公司,貨號:D2650),RIPA溶解產(chǎn)物、蛋白酶抑制劑、磷酸酶抑制劑(中國Service生物公司,貨號:M00620-FKB),抗TLR4抗體(Solarbio公司,貨號:K003881P),抗NF-κB抗體(美國Cayman Chemical,貨號:17493-1)。
1.2 動物和處理
雄性SD大鼠42只,8周齡,體質(zhì)量為220~280 g,購于江西省動物實驗中心(許可證號:SCXK (Gan) 2015-0019)。實驗前所有大鼠均在實驗環(huán)境中適應(yīng)1周,保證室溫(21±2)℃、濕度(50±5)%、12 h/12 h晝夜光照循環(huán),自由進食和飲水。動物實驗嚴格按照青島市中心醫(yī)院倫理委員會規(guī)定進行(KY-Y20190661)。
隨機取12只SD大鼠為假手術(shù)組(S組),其余30只參照Zea-Longa線栓法經(jīng)左側(cè)頸外-內(nèi)動脈插線建立大腦中動脈閉塞(MCAO)模型[11]。缺血2 h后,輕輕拉出線栓,實現(xiàn)缺血再灌注。術(shù)后2 h采用Zea-Longa標準評分[11],>1分者視為模型成功,將不成功的6只剔除。將建模成功的24只大鼠隨機分為對照組(C組)和菊酯組(CE組),每組12只。S組不插線,其余操作同C組和CE組。 CE組在手術(shù)前2 h腹腔內(nèi)注射2 mL 菊酯溶液(5 mg/kg),S組和CE組注射同體積生理鹽水。
1.3 檢測指標和方法
1.3.1 神經(jīng)行為功能評分 各組大鼠分別于腦缺血再灌注損傷后2、8、24 h采用Zea-Longa標準評分[11]。0分,沒有神經(jīng)功能缺損癥狀;1分,輕度局灶性神經(jīng)功能缺損(不能完全性伸展前肢);2分,中度局灶神經(jīng)功能缺損(行走時向健側(cè)劃圈);3分,重度神經(jīng)功能缺損(行走時向健側(cè)傾斜);4分,不能自主行走,意識水平下降。
1.3.2 TTC染色 缺血再灌注24 h后,每組取4只大鼠麻醉,從左心室穿刺以生理鹽水沖洗,完整取腦,放入切腦磨具中,冠狀位切片,每片約2 mm厚。每只取3張,將腦片置于20 g/L的TTC溶液中,37 ℃隔水培養(yǎng)箱中避光浸浴5 min。染色后將腦組織片置于40 g/L甲醛溶液中固定。正常腦組織在TTC溶液中被染成亮紅色,梗死區(qū)腦組織不被染色。固化24 h后照相,采用圖像處理軟件測量腦組織片各面缺血所占切片總面積的百分比。
1.3.3 細胞凋亡測定 每組取4只大鼠,取腦置于液氮、-80 ℃保存,連續(xù)冠狀位切片,厚度10 μm,每隔5張抽取1張,每只取3張,貼片,晾干。按照TUNEL試劑盒說明進行操作,用PBS緩沖液沖洗5 min。用10 g/L的Triton X-100(聚乙二醇辛基苯基醚)漂洗腦組織15 min,用PBS緩沖液沖洗3次,每次5 min。在100 mmol/L氨基乙酸中孵育20 min,PBS緩沖液沖洗3次,每次5 min。加入TUNEL反應(yīng)液,在暗濕盒中37 ℃孵育1 h,用PBS緩沖液沖洗3次,每次5 min。加入DAPI 孵育10 min,用超純水沖洗3次,每次5 min。最后封片,于4 ℃暗室中在光學顯微鏡下進行拍照。具有黃綠色熒光的為陽性細胞,即凋亡細胞。
1.3.4 TLR4和NF-κB蛋白表達 采用蛋白質(zhì)印跡法(Western blot)檢測。每組取4只大鼠,每只取腦組織標本100 mg,按蛋白提取試劑盒說明提取蛋白,用BCA試劑盒測定蛋白濃度。于蛋白樣本加入1/4體積5×SDS上樣緩沖液,以50 μg蛋白樣品用于SDS-PAGE凝膠電泳,200 mA恒電流轉(zhuǎn)膜至PVDF膜。TBS/T洗膜后用50 g/L的BSA封閉2 h,再以TBS/T洗膜后加入相應(yīng)濃度的抗體(抗TLR4抗體、抗NF-κB抗體),室溫下以側(cè)搖擺床緩慢搖動孵育2 h,并4 ℃孵育過夜,最后以TBS/T洗膜加入二抗(1∶5 000),室溫孵育2 h。TBS/T洗膜后用ECL發(fā)光液顯色成像。應(yīng)用Image J軟件比較目的條帶相對灰度值。每只實驗重復3次。
1.4 統(tǒng)計學分析
應(yīng)用SPSS 19.0軟件進行統(tǒng)計學處理。計量資料以±s表示,TTC染色結(jié)果、凋亡細胞水平及蛋白表達均數(shù)的比較采用單因素方差分析,多組間不同時間神經(jīng)功能缺損評分均數(shù)的比較采用重復測量設(shè)計的方差分析,多組間均數(shù)的兩兩均數(shù)比較采用Bonferroni方法。以P<0.05為差異有統(tǒng)計學意義。
2 結(jié) ?果
2.1 各組神經(jīng)功能缺損評分比較
缺血再灌注8、24 h后C組和CE組的神經(jīng)功能缺損評分均顯著高于S組,而CE組的神經(jīng)功能缺損評分又顯著低于C組,差異均有顯著意義(F=16.7~189.7,P<0.01)。說明給予菊酯抑制NF-κB后大鼠缺血再灌注損傷減小。見表1。
2.2 各組腦組織切片TTC染色比較
缺血再灌注24 h后,S組、C組和CE組的梗死區(qū)域分別為(6.32±2.76)%、(41.46±4.52)%和(29.51±3.78)%,S組的梗死區(qū)域明顯小于C組和CE組,而CE組的壞死區(qū)域則顯著小于C組,差異具有統(tǒng)計學意義(F=271.5,P<05)。說明給予菊酯抑制NF-κB后,大鼠局部腦組織梗死區(qū)域面積明顯縮小。見圖1A。
2.3 各組腦組織切片神經(jīng)細胞凋亡水平比較
腦缺血再灌注24 h后,S組、C組和CE組的 TUNEL陽性細胞分別為23.21±5.82、385.42±26.42和204.02±35.73。S組少見TUNEL陽性細胞,C組和CE組TUNEL陽性細胞數(shù)顯著多于S組(F=616.9,P<0.001)。與C組大鼠比較,CE組大鼠TUNEL陽性細胞數(shù)明顯降低,差異有統(tǒng)計學意義(P<0.05)。結(jié)果提示給予菊酯抑制NF-κB后,局部腦缺血再灌注大鼠的神經(jīng)細胞凋亡水平明顯下降。見圖1B~D。
2.4 各組TLR4和NF-κB蛋白表達比較
Western blot結(jié)果表明,缺血再灌注24 h后, C組和CE組大鼠的TLR4和NF-κB蛋白表達水平顯著高于S組(F=279.7、884.4,P<0.01)。同時,TLR4和NF-κB蛋白表達在CE組明顯低于C組(P<0.05)。提示菊酯可明顯抑制NF-κB表達,通過控制NF-κB/TLR4信號通路降低腦組織的缺血再灌注損傷。見圖2A~C。
3 討 ?論
缺血性腦血管病的發(fā)病機制是腦血流中斷,能量代謝紊亂,離子水平失衡,自由基和興奮性神經(jīng)毒性物質(zhì)產(chǎn)生[12]。TLR4廣泛分布于中樞神經(jīng)系統(tǒng),可以識別由于缺血再灌注損傷所釋放的內(nèi)源性配體,其可引起嚴重的炎癥反應(yīng),進而影響神經(jīng)系統(tǒng)功能[13-14]?;罨腘F-κB可誘導黏附分子的表達,其相應(yīng)的受體在炎癥反應(yīng)中發(fā)揮關(guān)鍵作用[15]。NF-κB/TLR4信號通路在腦缺血再灌注損傷中介導多種炎癥遞質(zhì)和金屬蛋白酶的產(chǎn)生和釋放,因此,控制NF-κB/TLR4信號通路可降低腦組織的缺血再灌注損傷[16-21]。
本研究通過建立大鼠腦局部缺血再灌注損傷動物模型,觀察TLR4和NF-κB在神經(jīng)損傷中的變化。通過應(yīng)用菊酯抑制NF-κB表達,從而明確NF-κB是否在腦缺血再灌注損傷中發(fā)揮作用。本文結(jié)果顯示,C組大鼠的神經(jīng)功能缺損評分明顯高于S組,這就說明缺血再灌注可嚴重破壞大鼠的神經(jīng)系統(tǒng)功能。另外,CE組的神經(jīng)功能缺損評分顯著低于C組,表明NF-κB抑制劑對大鼠神經(jīng)功能具有保護作用。本文采用TTC和TUNEL染色從形態(tài)學和凋亡細胞水平評價缺血再灌注對腦組織的損害。結(jié)果顯示,缺血再灌注能明顯增加腦梗死面積,提高腦組織中凋亡細胞水平。而菊酯干預(yù)則能顯著降低腦梗死面積和細胞凋亡水平,對抗缺血再灌注損傷,對大鼠腦組織起到保護作用。既往的研究結(jié)果顯示,腦梗死病人TLR4/NF-κB信號通路表達較健康人明顯升高,并且與腦血流量具有相關(guān)性[22-24]。我們通過Western blot技術(shù)檢測各組大鼠腦組織NF-κB和TLR4蛋白表達的結(jié)果表明,C組NF-κB和TLR4蛋白表達顯著高于S組,而兩者在CE組的表達又明顯低于C組。這說明缺血再灌注損害會提高腦組織NF-κB和TLR4的表達,而活化的NF-κB信號通路會導致腦組織損傷。這是因為腦局部缺血再灌注損傷中的內(nèi)源性和外源性物質(zhì)能提高NF-κB的表達,激活NF-κB信號通路,促使NF-κB從p50同源二聚體轉(zhuǎn)化成具有轉(zhuǎn)錄活性的p60異二聚體。而活化的NF-κB從細胞質(zhì)轉(zhuǎn)移到細胞核中,發(fā)揮轉(zhuǎn)錄調(diào)節(jié)作用,產(chǎn)生一系列炎癥因子,促進炎癥發(fā)生。此外,NF-κB p65/p50水平增高也表明NF-κB信號通路的活化,進一步導致大量炎癥因子的釋放。上述原因?qū)е碌难装Y反應(yīng)引起腦組織中凋亡細胞水平升高,神經(jīng)功能受損。腦損傷產(chǎn)生的內(nèi)源性物質(zhì)作為TLR4配體,可以增強炎癥反應(yīng)[25-29]。本文的研究結(jié)果還顯示,與C組比較,CE組NF-κB水平明顯下降,更進一步證明NF-κB在腦缺血再灌注損傷中的作用。
既往對TLR4/NF-κB信號通路在腦血管病中的作用研究多為對缺血性模型的研究,而對缺血再灌注模型研究較少。而缺血再灌注損傷也是影響病人治療效果及預(yù)后的一項重要因素。本文通過腦缺血再灌注損傷的大鼠模型證實,腦缺血再灌注損傷能夠提高TLR4和NF-κB的表達,激活TLR4/NF-κB信號通路,引起神經(jīng)細胞凋亡,影響神經(jīng)功能。通過抑制NF-κB可降低TLR4的表達,抑制TLR4/NF-κB信號通路激活,在局部腦缺血再灌注損傷中發(fā)揮保護作用。這為進一步研究缺血性腦梗死發(fā)生發(fā)展機制提供了一定理論基礎(chǔ),并且有可能為進一步研究缺血性腦血管病的治療方法提供參考。本研究仍存在一些不足,今后的研究中將進一步增加缺血組和缺血再灌注組的比較,以進一步明確TLR4/NF-κB信號通路在腦缺血再灌注損傷中的作用機制。
[參考文獻]
[1] PARK J S, HWANG N K, OH D H, et al. Effect of head lift exercise on kinematic motion of the hyolaryngeal complex and aspiration in patients with dysphagic stroke[J]. Journal of Oral Rehabilitation, 2017,44(5):385-391.
[2] KEPPEL HESSELINK J M. NS1209/SPD 502, a novel selective AMPA antagonist for stroke, neuropathic pain or epilepsy? drug development lessons learned[J]. Drug Development Research, 2017,78(2):75-80.
[3] SETO S W, CHANG D, JENKINS A, et al. Angiogenesis in ischemic stroke and angiogenic effects of Chinese herbal medicine[J]. Journal of Clinical Medicine, 2016,5(6):630-645.
[4] VASILEVA D, LUBENOVA D, MIHOVA M, et al. Orthostatic reactivity in patients with ischemic stroke in the chronic period[J]. Medical Science, 2015,3(3):397-402.
[5] BOISSERAND L S, KODAMA T, PAPASSIN J, et al. Biomaterial applications in Cell-Based therapy in experimental stroke[J]. Stem Cells International, 2016,2016:6810562. doi:10.1155/2016/6810562. PMID:27274738.
[6] LIANG Ying, HUANG Jian, TIAN Jingbin, et al. The prevalence and risk factors of stroke in patients with chronic schizophrenia[J]. Neuropsychiatric Disease and Treatment, 2016,12(9):1131-1134.
[7] QIN W Y, LUO Y, LING C, et al. Electroacupuncture could regulate the NF-κB signaling pathway to ameliorate theinflammatory injury in focal cerebral ischemia/reperfusion model rats[J]. Evidence-based Complementary and Alternative Medicine: ECAM, 2013,2013:924541. doi:10.1155/2013/924541. PMID:23970940.
[8] OSHIRO A H, OTSUKI D A, HAMAJI M W, et al. Diffe-rential Roles of TLR2 and TLR4 in acute focal cerebral ische-mia/reperfusion injury in mice[J]. Brain Res, 2009,25(1262):100-108.
[9] LIU Xin, CAO Yan, ZHANG Yan, et al. Teneligliptin inhi-bits lipopolysaccharide-induced cytotoxicity and inflammation ? ?in dental pulp cells[J]. International Immunopharmacology, 2019,8(73):57-63.
[10] 王娜,張雪梅,陳立杰. TLR4信號通路與炎癥相關(guān)性疾病[J]. 中國實驗診斷學, 2015,19(5):857-860.
[11] LONGA E Z, WEINSTEIN P R, CARLSON S, et al. Rever-sible middle cerebral artery occlusion without craniectomy in rats [J]. Stroke, 1989,20(1):84-91.
[12] HINOHARA H, KADOI Y, TAKAHASHI K, et al. Time course of changes in cerebral blood flow velocity after tourniquet deflation in patients with diabetes mellitus or previous stroke under sevoflurane anesthesia[J]. Journal of Anesthesia, 2011,25(3):409-414.
[13] WANG Ying, GE Pengfei, ZHU Yuhong. TLR2 and TLR4 in the brain injury caused by cerebral ischemia and reperfusion[J]. Mediators of Inflammation, 2013,2013:124614.
[14] FERRONATO S, SCURO A, FOCHI S, et al. Expression of TLR4-PTGE2 signaling genes in atherosclerotic carotid plaques and peripheral blood[J]. Molecular Biology Reports, 2019,46(1):1317-1321.
[15] WANG Ying, GE Pengfei, YANG Li, et al. Protection of ischemic post conditioning against transient focal ischemia-induced brain damage is associated with inhibition of neuroinflammation via modulation of TLR2 and TLR4 pathways[J]. Journal of Neuroinflammation, 2014,11(24):15.
[16] TOMUSCHAT C, O DONNELL A M,COYLE D, et al.Neuroprotective effect of kaempferol flycosides against brain injury and neuroinflammation by inhibiting the activation of NF-κB and STAT3 in transient focal stroke[J]. Pediatr Res, 2013,8(2):1787-1799.
[17] ZHANG Man, YIN Huajing, WANG Weiping, et al. Over-expressed human TREK-1 inhibits CHO cell proliferation via inhibiting PKA and p38 MAPK pathways and subsequently inducing G1 arrest[J]. Acta Pharmacologica Sinica, 2016,37(9):1190-1198.
[18] LEVITZ J, ROYAL P, COMOGLIO Y, et al. Long non-coding RNA C2dat1 regulates CaMKIIδ expression to promote neuronal survival through the NF-κB signaling pathway follo-wing cerebral ischemia[J]. Proc Natl Acad Sci USA, 2016,31(7):266-271.
[19] XU Q, DENG F, XING Z, et al. Long non-coding RNA C2dat1 regulates CaMKIIδ expression to promote neuronal survival through the NF-κB signaling pathway following cerebral ischemia[J]. Cell Death & Disease, 2016,7:e2173.
[20] NA Xinyu, LIU Zongyuan, REN Pengpeng, et al. Long non-coding RNA UCA1 contributes to the progression of prostate cancer and regulates proliferation through KLF4-KRT6/13 signaling pathway[J]. International Journal of Clinical and Experimental Medicine, 2015,8(8):12609-12616.
[21] XU Weihua, ZHANG Jianbin, DANG Zheng, et al. Long non-coding RNA URHC regulates cell proliferation and apoptosis via ZAK through the ERK/MAPK signaling pathway in hepatocellular carcinoma[J]. International Journal of Biological Sciences, 2014,10(7):664-676.
[22] 顧紅梅,邵陽. 急性腦梗死患者TLR4/NF-κB信號通路水平與腦血流量的相關(guān)性研究[J]. 卒中與神經(jīng)疾病, 2017,24(3):197-199,213.
[23] 李揚,李旭,葉衛(wèi)娜,等. 血管緊張素1-7通過TLR4/NF-κB信號通路拮抗大鼠腦缺血再灌注損傷[J]. 國際生物醫(yī)學工程雜志, 2018,41(6):499-503.
[24] 蔣騰,高麗,陸杰,等. 血管緊張素-(1-7)對大鼠腦缺血再灌注損傷后核因子-κB及下游炎癥因子的調(diào)控作用[J]. 中華神經(jīng)醫(yī)學雜志, 2013,12(1):19-23.
[25] ZHU H T, BIAN C, YUAN J C, et al. Curcumin attenuates acute inflammatory injury by inhibiting the TLR4/MyD88/NF-κB signaling pathway in experimental traumatic brain injury[J]. Journal of Neuroinflammation, 2014,27(11):97-110.
[26] LIU J, CHEN Q, JIAN Z, et al. Daphnetin protects against cerebral ischemia/reperfusion injury in mice via inhibition of TLR4/NF-κB signaling pathway[J]. Biomed Research International, 2016,2016:2816056. doi:10.1155/2016/2816056. PMID:28119924.
[27] QI Meng, ZHENG Lingli, QI Yan, et al. Dioscin attenuates renal ischemia/reperfusion injury by inhibiting the TLR4/MyD88 signaling pathway via up-regulation of HSP70[J]. Pharmacological Research, 2015,100:341-352.
[28] ZENG Huiqing, YANG Lijuan, ZHANG Xiaobin, et al. Dioscin prevents LPSinduced acute lung injury through inhibiting the TLR4/MyD88 signaling pathway via upregulation of HSP70[J]. Mol Med Rep, 2018,17(5):6752-6758.
[29] ZHANG Xiangsheng, LI Wei, WU Qi, et al. Resveratrol attenuates acute inflammatory injury in experimental subarachnoid hemorrhage in rats via inhibition of TLR4 pathway[J]. Int J Mol Sci, 2016,17(8):1331. PMCID: PMC5000728.
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