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1美国生物圈二号内生长在高CO_2浓度下的10种植物气孔导度、蒸腾速率及水分利用效率的变化显示文摘报道了美国生物圈二号内生长在高CO_2浓度下(>2200μmol·mol^(-1))4.5年后的5种热带雨林植物和5种荒漠植物气孔导度、蒸腾速率和水分利用效率的变化。结果表明:热带雨林植物在CO_2浓度为350~400μmol·mol^(-1)时的气孔导度、蒸腾速率和水分利用效率分别为:(127.4±65.6)mmol·m^(-2)·s^(-1)、(2.04±0.61)mmol·m^(-2)·s^(-1)和(2.90±0.55)μmol CO_2·mmol^(-1) H_2O,而在700~820μmol·mol^(-1)时为(61.3±30.5)mmol·m^(-2)·s^(-1)、(1.54±0.65)mmol·m^(-2)·s^(-1)和(8.45±2.71)μmol CO_2·mmol^(-1) H_2O;荒漠植物气孔导度和蒸腾速率则分别由CO_2 320~400μmol·mol^(-1)时的(142.8±94.6)和(2.09±0.71)下降到820~850μmol·mol^(-1)时的(57.7±35.8)和(1.36±0.52)mmol·m^(-2)·s^(-1),水分利用效率由(4.69±1.39)上升到(9.68±1.61)μmol CO_2·mmol^(-1) H_20。在低CO_2浓度时植物的气孔导度、蒸腾速率和水分利用效率受光照强度的影响较高CO_2浓度时明显,一般雨林植物三项指标在光照强度为500μmol·m^(-2)·s^(-1)时达到饱和,而荒漠植物在1000μmol·m^(-2)·s^(-1)时达到饱和。不同植物中,以荒漠C_3植物粉蓝烟草(Nicotiana glau-ca Grah.)的气孔导度。蒋高明 林光辉 Bruno D V Marino 1997Acta Botanica Sinica1997,39,6:55
2欧洲早产儿呼吸窘迫综合征防治共识指南(2013版)显示文摘本次指南更新包括了自2010年以来Cochrane系统评价和医学文献中的最新证据,并采纳了一种新的证据评估分级系统(GRADE)。以往关于早期肺表面活性物质和持续气道正压通气治疗的推荐目前拥有了更坚定的循证依据。对产房复苏、稳定生命体征等内容进行了较大扩充。生命体征稳定后的氧疗目前仍存在一定的争议,但是在获得更多的证据之前,血氧饱和度的目标范围不应低于90%,支持治疗对于超早早产儿仍然极为重要。指南对其他注意事项进行了缩减。Sweet D Carnielli V Greisen G Hallman M Ozek E Plavka R Saugstad OD Simeoni U Speer CP Halliday HL 王敏婕 袁琳 陈超 2014中华儿科杂志2014,52,10:34
3急性缺血性卒中的血管内治疗:神经介入外科学学会实践标准委员会的报告显示文摘目的总结采用血管内技术治疗急性缺血性卒中的有关证据并等级分类。方法对美国心脏协会(American Heart Association,AHA)以前发表的推荐意见进行审查并作为当前流程的基础。在此这基础上,进行系统的文献回顾以评估支持急性缺血性卒中血管内治疗的证据。根据AHA卒中委员会和牛津大学循证医学中心提出的循证医学证据分级指南进行评估。对操作安全性、技术效果以及对临床转归的影响进行特别审核。K A Blackham P M Meyers T A Abruzzo F C Alberquerque D Fiorella J Fraser D Frei C D Gandhi D V Heck J A Hirsch D P Hsu M Jayaraman S Narayanan C Prestigiacomo J L Sunshine 包元飞(译) 李永坤(译) 刘新峰(译) 2012国际脑血管病杂志2012,20,12:28
4Pancreatic fistula after pancreatectomy:Evolving definitions,preventive strategies and modern management显示文摘Pancreatic resection is the treatment of choice for pancreatic malignancy and certain benign pancreatic disorders. However, pancreatic resection is technically a demanding procedure and whereas mortality after a pancreaticoduodenectomy is currently < 3%-5% in experienced high-volume centers, post-operative morbidity is considerable, about 30%-50%. At present, the single most significant cause of morbidity and mortality after pancreatectomy is the development of pancreatic leakage and fistula (PF). The occurrence of a PF increases the length of hospital stay and the cost of treatment, requires additional investigations and procedures, and can result in life-threatening complications. There is no universally accepted definition of PF that would allow standardized reporting and proper comparison of outcomes between different centers. However, early recognition of a PF and prompt institution of appropriate treatment is critical to the prevention of potentially devastating consequences. The present article, reviews the evolution of post resection pancreatic fistula as a concept, and discusses evolving definitions, the current preventive strategies and the management of this problem.Shailesh V Shrikhande Melroy A D'Souza 2008World Journal of Gastroenterology2008,14,38:26
5专著《几何不等式新进展》的补遗(Ⅰ)(英文)显示文摘本文综述了专著 AGI 出版后几何不等式的最新进展,尽可能全面地收集了1987—1990年间的有关文献,更多地反映了中国数学家的工作成果。Mitrinovic D S Pecaric JE Volenec V 陈计 1991宁波大学学报(理工版)1991,4,2:23
6Endoscopic management of biliary strictures after liver transplantation显示文摘Bile duct strictures remain a major source of morbidity after orthotopic liver transplantation (OLT). Biliary strictures are classifi ed as anastomotic or non-anastomotic strictures according to location and are defi ned by distinct clinical behaviors. Anastomotic strictures are localized and short. The outcome of endoscopic treatment for anastomotic strictures is excellent. Nonanastomotic strictures often result from ischemic and immunological events, occur earlier and are usually multiple and longer. They are characterized by a far less favorable response to endoscopic management, higher recurrence rates, graft loss and need for retransplantation. Living donor OLT patients present a unique set of challenges arising from technical factors, and stricture risk for both recipients and donors. Endoscopic treatment of living donor OLT patients is less promising. Current endoscopic strategies for biliary strictures after OLT include repeated balloon dilations and placement of multiple side-by-side plastic stents. Lifelong surveillance is required in all types of strictures. Despite improvements in incidence and long term outcomes with endoscopic management, and a reduced need for surgical treatment, the impact of strictures on patients after OLT is signifi cant. Future considerations include new endoscopic technologies and improved stents, which could potentially allow for a decreased number of interventions, increased intervals before retreatment, and decreased reliance on percutaneous and surgical modalities. This review focuses on the role of endoscopy in biliary strictures, one of the most common biliary complications after OLT.Emmanuelle D Williams Peter V Draganov 2009World Journal of Gastroenterology2009,15,30:20
7皮质下小血管病诊断的共识声明显示文摘血管性认知损害是用于描述一组涉及大血管和小血管的散发性和遗传性异质性疾病的诊断术语。皮质下小血管病可导致腔隙性梗死和进行性白质损害。被称为宾斯旺格病(Binswanger's disease, BD)的进行性白质损害患者构成了从单纯血管性疾病到合并神经变性病变的疾病谱。BD患者是一个相对同质性的亚组,存在缺氧缺血、腔隙性梗死和炎症,它们协同作用破坏血脑屏障和髓鞘。通过临床、脑脊液、神经心理学和影像学检查获得的多模式疾病标记物能促进该亚组患者的鉴别。本共识声明确定了一系列基于基础病理学改变的潜在生物学标记物,这将有助于诊断以及将来协作性治疗试验的患者选择。Gary A Rosenberg Anders Wallin Joanna M Wardlaw Hugh S Markus Joan Montaner Leslie Wolfson Costantino Iadecola Berislav V Zlokovic Anne Joutel Martin Dichgans Marco Duering Reinhold Schmidt Amos D Korczyn Lea T Grinberg Helena C Chui Vladimir Hachinski 王训师 张劼 陈涵丰 俞娅美 徐子奇 罗本燕 2016国际脑血管病杂志2016,24,6:18
8纳秒、皮秒和飞秒激光脉冲对材料表面的改性(英文)显示文摘对基体材料镉镍铁合金600和多层TiAlN/TiN涂层的激光表面改性在基础研究和实际应用中有着很好的前景。本文观察了由超短脉冲(fs和ns)和短脉冲(ns)激光器引起的镉镍铁合金600和TiAlN/TiN镀层的表面变化。结果显示,3种激光都能使靶面发生形态改变,超短脉冲的破坏轮廓更为清晰。与ps激光脉冲相比,fs激光脉冲能产生更严重的破坏。与产生半球体形状的ps激光束相反,fs激光脉冲产生的破坏斑是圆锥形的。另外,ns脉冲辐照时热效应占支配地位,且所有的辐照都伴随着等离子体。TRTICAM S GAKOVIC B M RADAK B B BATANI D TARASENKO V F PETROVIC S STASIC J MILOVANOVIC D KRMPOT A JELENKOVIC B 2011光学精密工程2011,19,2:18
9欧洲新生儿呼吸窘迫综合征防治共识显示文摘呼吸窘迫综合征(RDS)是由于肺表面活性物质(PS)缺乏及肺结构发育不成熟所致,多见于早产儿,自然病程为出生当时或生后很快发病,并在生后2d内进行性恶化,如不及时治疗,因进行性缺氧和呼吸衰竭而死亡。存活者出生后2—4d病情开始改善。RDS临床表现早期出现呼吸窘迫如紫绀、呻吟、吸凹和呼吸急促,然后进一步发展为呼吸衰竭,血气分析结果可提示呼吸衰竭的严重性。胸部X线典型的毛玻璃样改变和支气管充气征可以确诊。Vermont Oxford新生儿协作网对RDS的定义为:Sweet D Bevilacqua G Carnielli V Greisen G Plavka R Didrik Saugstad O Simeoni U Speer CP Valls-I-Soler A Halliday H 袁琳(译) 陈超(译) 杜立中(校) 2008中华儿科杂志2008,46,1:17
10Incidence and mortality of primary liver cancer in England and Wales: Changing patterns and ethnic variations显示文摘AIM: To explore recent trends, modes of diagnosis, ethnic distribution and the mortality to incidence ratio of primary liver cancer by subtypes in England and Wales. METHODS: We obtained incidence(1979-2008) and mortality(1968-2008) data for primary liver cancer for England and Wales and calculated age-standardised incidence and mortality rates. Trends in age-standardised mortality(ASMR) and incidence(ASIR) rates and basis of diagnosis of primary liver cancer and subcategories: hepatocellular carcinoma, intrahepatic bile duct and unspecified liver tumours, were analysed over the study period. Changes in guidelines for the diagnosis of primary liver cancer(PLC) may impact changing trends in the rates that may be obtained. We thus explored changes in the mode of diagnosis as reported to cancer registries. Furthermore, we examined the distribution of these tumours by ethnicity. Most of the statistical manipulations of these data was carried out in Microsoft excel(Seattle, Washington, United Sttaes). Additional epidemiological statistics were done in Epi Info software(Atlanta, GA, United Sttaes). To define patterns of change over time, we evaluated trends in ASMR and ASIR of PLC and intrahepatic bile duct carcinoma(IHBD) using a least squares regression line fitted to the natural logarithm of the mortality and incidence rates. We estimated the patterns of survival over subsequent 5 and 10 years using complement of mortality to incidence ratio(1-MIR). RESULTS: Age-standardised mortality rate of primary liver cancer increased in both sexes: from 2.56 and 1.29/100000 in 1968 to 5.10 and 2.63/100000 in 2008 for men and women respectively. The use of histology for diagnostic confirmation of primary liver cancer increased from 35.7% of registered cases in 1993 to plateau at about 50% during 2005 to 2008. Reliance on cytology as a basis of diagnosis has maintained a downward trend throughout the study period. Although approximately 30% of the PLC registrations had information on ethnicity, there was a relatively higher registration of the major tumour subtypes in patients whose ethnic backgrounds were from high incident regions of the world. Survival from PLC is estimated to get poorer in 10 years(2018) relative to 2008, particularly as a result of IHBD. CONCLUSION: Incidence and mortality of PLC, and particularly IHBD, have continued to rise in England and Wales. Changes in the modes of diagnosis may be contributing.Nimzing G Ladep Shahid A Khan Mary ME Crossey Andrew V Thillainayagam Simon D Taylor-Robinson Mireille B Toledano 2014World Journal of Gastroenterology2014,20,6:15
11Phytochemical and anti-bacterial activity of epidermal glands extract of Christella parasitica (L.) H. Lev.显示文摘Objective:To study the morphology,biochemistry and bioactivity of the epidermal glands of the glandular morphotype of Christella parasitica(C.parasitica)(L.) H.Lev.Methods: Morphological studies on epidermal glands were earned out by using light microscope and scanning electron microscope.To prepare the extract,the shade-dried fronds of glandular morphotype were soaked in acetone.For antibacterial studies paper disc method was followed by using various pathogenic bacteria.Results:Detailed micromorphological,phytochemical and bioactivity studies on a medicinal fern C.parasitica(L.) H.Lev.showed its inlraspecific variation in antibacterial activity.The presence or absence of the epidermal glands was the key factor for antibacterial activity in the morphovariants of this species.The epidermal glands were orange-coloured,stalked and elongated ones of about 84.2μm×45μm,and distributed on the undersurface of cosla,coslules and veins in croziers,young and mature leaves.Frequency of glands varied from 15/cm on costa in mature leaves to 140/cm on costules in croziers.The acetone extract of the glands showed antibacterial activities and also toxic effect against mosquito larvae and tadpoles of frog.Preliminary phytochemical analysis and HPLC studies of the gland extract showed the presence of various kinds of terpenoids,alkaloids,tannins,saponins and flavonoids in it.Conclusions:The present study shows that epidermal glands of the glandular morphotype of C. parasitica(L.) H.Lev.have several bioactive compounds and such rare moiphovariant should be conserved in nature.The next step is to isolate the pure compounds and to screen the bioactivity of individual compounds of the epidermal glands.Paul Raj K Irudayaraj V Johnson M Patric Raja D 2011Asian Pacific Journal of Tropical Biomedicine2011,1,1:14
12气象卫星云图的多分辨小波分解及人工神经网络降水估计研究显示文摘采用多分辨小波分析对卫星图象进行预处理 ,在保留其特征信息的同时 ,减小了数据量 ,改善了神经网络训练过程的收敛性能 ,提高了处理速度。采用这一方法根据 GOES- 8的红外亮温图象和气象雷达资料对巴西圣保罗州中部的降水量估计进行了试验 ,取得了良好的效果。李伟钢 Maria C V Ramirez Nelson J Ferreira 石立华 Leonardo D de A Sá 2000南京气象学院学报2000,23,2:13
13肽酰基精氨酸脱亚氨酶4和中性粒细胞胞外诱捕网形成在实验性动脉粥样硬化和动脉损伤中的作用:浅表糜烂的影响显示文摘中性粒细胞可能促进人类动脉粥样硬化的血栓并发症的发生。特别是中性粒细胞胞外诱捕网(neutrophil extracellular traps,NETs)可加剧局部炎症,并放大和加剧动脉内膜损伤和血栓形成。肽酰基精氨酸脱亚氨酶4(peptidyl arginine deiminase 4,PAD4)参与NET的形成,但对该酶在动脉粥样硬化血栓形成中的作用的认识仍然不足。刘青 叶鹏 Franck G Mawson TL Folco EJ Molinaro R Ruvkun V Engelbertsen D Liu X Tesmenitsky Y Shvartz F Sukhova GK Michel JB Nicoletti A Lichtman AH Wagner DD Croce KJ Libby P 2018中华高血压杂志2018,26,5:13
14MicroRNA-185通过靶向调节DN-MT1/PTEN/Akt通路抑制肝细胞癌的生长显示文摘近来研究表明miRNAs与肝癌的发生密切相关,然而单个miRNAs的具体作用机制仍未完全阐明。作者对microR-NA-185(miR-185)在肝细胞癌生物学功能和分子机制方面做了一些研究。实验发现,与非肿瘤性的肝脏实质相比, miR-185在人肝细胞癌组织中的表达减少;qRT-PCR检测显示,与原代肝细胞相比, miR-185在人肝细胞癌细胞中的表达下降;在体外人肝细胞癌细胞中miR-185的过表达会抑制细胞的增殖和侵袭,并且阻止SCID小鼠体内肿瘤的生长。miR-185的过表达能够抑制肝细胞癌细胞中DNMT13′端非翻译区域荧光素酶的活性,当 miR-185结合位点发生突变时,就不存在该效应;miR-185的复制或过表达会减少肝细胞癌细胞中DNMT1蛋白的表达。这些结果表明DNMT1是miR-185在肝细胞癌细胞中的靶向作用蛋白。 DNMT1在miR-185诱导抑制肝细胞癌的增殖中所起的作用,可进一步通过DNMT1的过表达阻止miR-185诱导抑制肝细胞癌细胞的增殖和侵袭这一事实所证实。 miR-185的复制或过表达能够减少PTEN启动子DNA甲基化并且提高PTEN的表达,从而抑制Akt磷酸化;如果DNMT1过表达,这些效应刚好相反。以上结果表明:miR-185靶向作用于DNMT1,通过诱导PTEN和抑制Akt,从而抑制肝细胞癌细胞的增殖,活化或激活miR-185可能成为肝细胞癌新的治疗策略之一。Qadir X V Han C Lu D 魏建国 许春伟 2014临床与实验病理学杂志2014,30,12:12
15Schistosoma mansoni proteins attenuate gastrointestinal motility disturbances during experimental colitis in mice显示文摘AIM:To investigate the therapeutic effect of Schistosoma mansoni(S.mansoni) soluble worm proteins on gastrointestinal motility disturbances during experimental colitis in mice. METHODS:Colitis was induced by intrarectal injection of trinitrobenzene sulphate(TNBS) and 6 h later,mice were treated ip with S.mansoni proteins.Experiments were performed 5 d after TNBS injection.Inflammationwas quantified using validated inflammation parameters. Gastric emptying and geometric center were measured to assess in vivo gastrointestinal motility.Peristaltic activity of distal colonic segments was studied in vitro using a modified Trendelenburg set-up.Cytokine profiles of T-lymphocytes isolated from the colon were determined by real time reverse transcriptase-polymerase chain reaction. RESULTS:Intracolonic injection of TNBS caused severe colitis.Treatment with S.mansoni proteins significantly ameliorated colonic inflammation after 5 d.TNBS did not affect gastric emptying but significantly decreased the geometric center and impaired colonic peristaltic activity 5 d after the induction of colitis.Treatment with S.mansoni proteins ameliorated these in vivo and in vitro motility disturbances.In addition,TNBS injection caused a downregulation of effector T cell cytokines after 5 d,whereas a S.mansoni protein effect was no longer observed at this time point. CONCLUSION:Treatment with S.mansoni proteins attenuated intestinal inflammation and ameliorated motility disturbances during murine experimental colitis.Nathalie E Ruyssers Benedicte Y De Winter Joris G De Man Natacha D Ruyssers Ann J Van Gils Alex Loukas Mark S Pearson Joel V Weinstock Paul A Pelckmans Tom G Moreels 2010World Journal of Gastroenterology2010,16,6:11
16烟酰胺磷酸核糖基转移酶促进肺血管重塑,是肺动脉高压的治疗靶点显示文摘肺动脉高压(pulmonary arterial hypertension,PAH)是一种严重的进行性疾病,其标志之一是肺血管重塑。烟酰胺磷酸核糖基转移酶(nicotinamide phosphoribosyl transferase,NAMPT)是调节细胞内烟酰胺腺嘌呤二核苷酸水平、细胞氧化还原状态,调节组蛋白脱乙酰酶,促进细胞增殖和抑制凋亡的一种细胞酶。研究人员假设NAMPT可促进肺血管重塑,Chen J Sysol JR Singla S Zhao S Yamamura A Valdez-Jasso D Abbasi T Shioura KM Sahni S Reddy V Sridhar A Gao H Torres J Camp SM Tang H Ye SQ Comhair S Dweik R Hassoun P Yuan JX Garcia JG Machado RF 刘莉 叶鹏 2017中华高血压杂志2017,25,2:10
17疝修补术:寻找理想的网片显示文摘要做到有效的网片修补是困难的。在过去的50年中,疝修补技术有了长足的进步,但仍然需要一些新的观念和方法来巩固疝修补术已经取得的成绩。在欧洲疝学会第30次国际大会上,疝修补术及网片试验评估领域的9名专家共同参加了一次圆桌会议,讨论当今疝修补术中亟待解决的问题;内容包括'理想'网片的定义及'理想'的网片材料。讨论的其他内容还包括轻量型网片的特点,网片替代物,外科医生在疝修补术中的作用,当今疝修补术中亟待解决的问题,以及最佳的动物试验模型。尽管人们对于理想网片的构成还没有定论,但对其重要的特点却有了更深的理解。希望这些建议可以促进疝治疗的发展,并催生出最为有效的疝修补网片材料。Bringman S Conze J Cuccumllo D Deprest j Junge K Klosterhalfen B Parra-Davila E Ramshaw B Schumpelick V 2010中国实用外科杂志2010,30,12:10
18Clarifying sub-genomic positions of QTLs for flowering habit and fruit quality in U.S. strawberry (Fragaria×ananassa) breeding populations using pedigree-based QTL analysis显示文摘The cultivated strawberry(Fragaria×ananassa)is consumed worldwide for its flavor and nutritional benefits.Genetic analysis of commercially important traits in strawberry are important for the development of breeding methods and tools for this species.Although several quantitative trait loci(QTL)have been previously detected for fruit quality and flowering traits using low-density genetic maps,clarity on the sub-genomic locations of these QTLs was missing.Recent discoveries in allo-octoploid strawberry genomics led to the development of the IStraw90 single-nucleotide polymorphism(SNP)array,enabling high-density genetic maps and finer resolution QTL analysis.In this study,breeder-specified traits were evaluated in the Eastern(Michigan)and Western(Oregon)United States for a common set of breeding populations during 2 years.Several QTLs were validated for soluble solids content(SSC),fruit weight(FWT),pH and titratable acidity(TA)using a pedigree-based QTL analysis approach.For fruit quality,a QTL for SSC on linkage group(LG)6A,a QTL for FWT on LG 2BII,a QTL for pH on LG 4CII and two QTLs for TA on LGs 2A and 5B were detected.In addition,a large-effect QTL for flowering was detected at the distal end of LG 4A,coinciding with the FaPFRU locus.Marker haplotype analysis in the FaPFRU region indicated that the homozygous recessive genotype was highly predictive of seasonal flowering.SNP probes in the FaPFRU region may help facilitate marker-assisted selection for this trait.Sujeet Verma Jason D Zurn Natalia Salinas Megan M Mathey Beatrice Denoyes James F Hancock Chad E Finn Nahla V Bassil Vance M Whitaker 2017Horticulture Research2017,4,1:10
19血栓性血小板减少性紫癜患者vWF裂解蛋白酶抗原和活性的检测及意义显示文摘目的研究血管性血友病因子裂解蛋白酶(ADAMTS13)抗原含量和活性在血栓性血小板减少性紫癜(TTP)患者及遗传性 TTP 家族突变携带者中变化的情况。方法用残余胶原结合实验(RCBA)检测13例 TTP 患者共28份血浆标本[含血浆置换(PE)前后]及10例携带者的 ADAMTS13活性;用新近建立的三抗体夹心酶联免疫反应法检测标本的 ADAMTS13抗原含量。结果正常对照组 ADAMTS13含量为(600.93±145.36)mU/ml(设白种人混合血浆的 ADAMTS13抗原含量为1000mU/ml),活性为(74.79±11.81)%。遗传性 TTP 患者 ADAMTS13抗原含量和活性治疗前和发病间期均明显减低,PE 后恢复;其家族中携带者 ADAMTS13抗原含量为(331.40±109.85)mU/ml,活性为(66.79±12.82)%(与对照组比较,P 值分别<0.01和>0.05);原发性 TTP 患者 PE 前 ADAMTS13抗原含量为(98.7±82.08)mU/ml,活性为(22.23±19.07)%(与对照组比较,P 值均<0.01);PE 后ADAMTS13 抗原含量为(449.4±232.33)mU/ml,活性为(60.92±22.33)%(与对照组比较,P 值分别<0.01和>0.05);1例继发性 TTP 患者 PE 后 ADAMTS13抗原含量远高于正常,活性仅为6.00%结论治疗前的 TTP 患者 ADAMTS13抗原含量和活性均明显减低。大多数患者两指标变化趋势一致,也有个别患者两指标变化趋势相反,前者可能因为遗传因素或体内免疫系统的廓清作用,后者可能因为抗 ADAMTS13抗体仅抑制了 ADAMTS13的活性而未影响其抗原的含量或其他未知原因所致。刘芳 BF Hendrik 董宁征 白霞 V Karen D Hans 阮长耿 2006中华血液学杂志2006,27,3:10
20Differential regulation of protein synthesis in skeletal muscle and liver of neonatal pigs by leucine through an mTORC1-dependent pathway显示文摘Neonatal growth is characterized by a high protein synthesis rate that is largely due to an enhanced sensitivity to the postprandial rise in insulin and amino acids, especially leucine. The mechanism of leucine's action in vivo is not well understood. In this study, we investigated the effect of leucine infusion on protein synthesis in skeletal muscle and liver of neonatal pigs. To evaluate the mode of action of leucine, we used rapamycin, an inhibitor of mammalian target of rapamycin (mTOR) complex-1 (mTORC1). Overnight-fasted 7-day-old piglets were treated with rapamycin for 1 hour and then infused with leucine (400 μmol·kg -1 ·h -1 ) for 1 hour. Leucine infusion increased the rate of protein synthesis, and ribosomal protein S6 kinase 1 (S6K1) and eukaryotic initiation factor (eIF) 4E-binding protein-1 (4E-BP1) phosphorylation in gastrocnemius and masseter muscles (P < 0.05), but not in the liver. The leucine-induced stimulation of protein synthesis and S6K1 and 4E-BP1 phosphorylation were completely blocked by rapamycin, suggesting that leucine action is by an mTORC1-dependent mechanism. Neither leucine nor rapamycin had any effect on the activation of the upstream mTORC1 regulators, AMP-activated protein kinase and protein kinase B, in skeletal muscle or liver. The activation of eIF2a and elongation factor 2 was not affected by leucine or rapamycin, indicating that these two pathways are not limiting steps of leucine-induced protein synthesis. These results suggest that leucine stimulates muscle protein synthesis in neonatal pigs by inducing the activation of mTORC1 and its downstream pathway leading to mRNA translation.Agus Suryawan Hanh V Nguyen Rosemarie D Almonaci Teresa A Davis 2012Journal of Animal Science and Biotechnology2012,3,1:9
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