防御素在肠黏膜屏障功能中的作用

肠黏膜不仅有消化和吸收功能,而且还具有重要的防御性屏障功能,它可以使机体的内环境保持相对稳定以维持机体的正常生命活动。当肠黏膜屏障受到损伤时,肠道中的微生物和毒素会突破肠黏膜屏障,进入门静脉和淋巴系统从而引起细菌移位,甚至发展为全身性的炎症反应综合征（systemic inflammatory response syndrome,SIRS）以及多器官功能衰竭综合征（multiple organs defic iency syndrome,MODS）。     

低聚果糖对溃疡性结肠炎模型小鼠肠黏膜屏障影响的研究

目的 探讨低聚果糖对溃疡性结肠炎（UC）模型小鼠肠黏膜屏障的调节作用及可能机制。方法 小鼠随机分成3组：正常对照（NC）组、模型（MD）组和低聚果糖（FOS）组,采用葡聚糖硫酸钠制作UC小鼠模型。造模7 d同时给予干预治疗,停用造模药物并后续治疗7 d。采用细菌定量测定法检测肠道菌群,放射免疫法检测肠黏膜sIgA,ELISA法检测小鼠肠黏膜IL-10、TNF-α和IL-6水平。结果 模型组小鼠存在肠道菌群失调（t=2.088,2.036,2.203,2.109,P<0.05）,其TNF-α、IL-6水平高于正常对照组（t=1.734,1.801,P<0.05）,肠黏膜sIgA、IL-10低于正常对照组（t=1.820,1.806,P<0.05）;低聚果糖组肠道菌群失调状况较模型组有所改善,其TNF-α、IL-6水平低于正常对照组（t=1.980,1.816,1.936,1.920,1.969,1.893,P<0.05）,肠黏膜sIgA、IL-10高于正常对照组（t=1.801,1.796,P<0.05）。结论 低聚果糖可改善溃疡性结肠炎模型小鼠肠道菌群屏障功能,可以提高肠黏膜sIgA和抗炎细胞因子IL-10的水平并降低致炎细胞因子TNF-α和IL-6的水平,通过调节肠道过度的免疫反应,使免疫屏障功能得到一定恢复。     

缺氧环境下自噬对肠黏膜屏障的影响

肠黏膜屏障是机体屏障系统的重要组成部分,可有效阻止肠道寄生菌及其毒素向肠腔外组织移位,防止机体受内源性微生物及其毒素的侵害.自噬在各种生命活动中发挥着重要作用.在缺血缺氧等应激状态下,自噬对细胞存活、清除细胞内衰老细胞器等起重要作用.缺氧可诱导自噬.多数情况下自噬被认为是细胞的一种保护作用,然而在某些条件下细胞过度自噬也能导致细胞凋亡.肠黏膜屏障损伤的研究是目前医学研究领域的一个重要课题,本文就自噬在缺氧环境下对肠黏膜屏障的影响做一综述.     

短链脂肪酸对肠黏膜屏障的影响

肠黏膜屏障具有将致病性抗原等肠内物质与内环境隔离的功能,以维持内环境的相对稳定和机体的正常生命活动。其功能的维持依赖于人肠黏膜上皮细胞、肠道内正常菌群、肠道内分泌物和肠相关免疫细胞之间的功能协调,而其功能的发挥又受体内许多信号分子的影响。短链脂肪酸（short-chain fatty acids,SCFAs）就是其中一种重要的信号分子。SCFAs是肠道菌群的主要代谢产物之一,是肠道菌群与宿主代谢相互作用的媒介。宿主体内的SCFAs主要来自肠道菌群对膳食纤维的酵解,越来越多的研究证实,SCFAs不仅可以被肠道菌群利用,还可调节肠黏膜屏障及多种组织器官的代谢。本文主要就SCFAs对肠黏膜屏障的影响进行综述。

     

急进高原大鼠肠黏膜机械屏障损伤后细胞自噬变化的初步研究

目的探讨急进高原大鼠肠黏膜机械屏障损伤后细胞自噬的变化情况。方法50只Wistar大鼠随机分为5组：平原组,急进高原6h组、12h组、24h组、48h组,每组各10只。通过低压低氧动物实验舱模拟急进海拔4767m建立急进高原大鼠模型。观察各组大鼠肠黏膜机械屏障损伤情况,用透射电镜观察肠上皮细胞中自噬体;用免疫组织化学法检测肠上皮细胞中自噬相关蛋白Beclinl及LC3B表达。结果与平原组比较,急进高原组可使其肠黏膜机械屏障发生损伤,并且在急进高原肠黏膜损伤6h后可观测到自噬体,24h后检测到自噬相关蛋白Beclinl及LC3B表达显著增高（P〈0．01）。结论急进高原组大鼠肠黏膜机械屏障损伤后自噬相关蛋白Beclinl及LC3B表达明显增加,表明急进高原大鼠肠黏膜机械屏障损伤后细胞自噬活性上调。     

肠黏膜屏障与病原细菌感染

人的肠道是一个非常复杂的环境,在这里存在有数量庞大的多种多样的微生物群落,它们的合集又通称为肠道菌群(gut microbiota)。通常情况下,人体与肠道菌群和平共处,互利互惠。肠道内环境与微生物的稳态主要依赖于肠黏膜的存在,它包括了上皮细胞层、固有层和黏膜肌层。肠黏膜协同其分泌的黏液层、黏膜免疫系统、以及其上依附的肠道菌群等一同组成了肠黏膜屏障,以抵御各种外界不利因素,尤其是病原细菌的侵袭。本文旨在概述肠道黏膜屏障与部分相关常见病原细菌感染机制的研究进展,并为科学研究和临床诊疗提供新思路。     

高原缺氧与肠黏膜屏障损伤研究

高原环境具有气压低、氧分压低、辐射强、寒冷、风大、湿度低、灾害天气多等特点,这种急剧变化的气候环境是导致肠黏膜损伤的关键因素。肠黏膜屏障作为机体发挥防御功能的防线之一,可以保护机体不受内源性微生物及其毒素的伤害。研究高原缺氧下肠黏膜损伤的机制,将有助于高原胃肠道疾病的诊治。多数研究结果表明,高原缺氧环境下肠黏膜的损伤可能与交感神经兴奋、遗传、氧自由基生成、自噬、微生态失衡等因素有关,以下就此进行概述。     

布拉酵母菌散对肝硬化大鼠肠黏膜屏障保护作用的实验研究

目的研究布拉酵母菌散对肝硬化大鼠肠黏膜屏障的保护作用及其可能机制。方法采用皮下注射40%CCL4橄榄油溶液+10%酒精饮料诱导肝硬化模型。造模成功后,治疗组用布拉酵母菌灌胃[75×108CFU/(kg·d)],对照组、模型组给予等容量的生理盐水灌胃,连续14 d。采用鲎试剂终点显色法检测血浆内毒素水平,应用分光光度法测定小肠组织二胺氧化酶(DAO)活性,应用自动生化分析仪检测血清丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)变化。结果模型组血浆内毒素水平[(0.251±0.011)EU/m L]较治疗组[(0.168±0.012)EU/m L]明显升高,差异有统计学意义(P0.01);模型组肠组织DAO活性为(0.432±0.074)U/mg,明显较对照组[(0.728±0.065)U/mg]降低,差异有统计学意义(P0.01),治疗组DAO活性为(0.548±0.053)U/mg,与模型组相比较,肠DAO活性升高,差异有统计学意义(P0.01),模型组、治疗组肠组织DAO活性较对照组明显降低(P0.01);模型组血清ALT、AST含量分别为(133.89±8.09)U/m L、(176.92±10.94)U/m L,比对照组ALT、AST含量[(36.73±6.95)U/m L、(41.35±10.07)U/m L]明显升高,P0.01;治疗组[(95.76±7.27)U/m L、(158.02±5.94)U/m L]与模型组相比较,ALT、AST含量下降,差异有统计学意义(P0.01)。结论肝硬化大鼠存在肠黏膜屏障受损,布拉酵母菌可通过调整肠道菌群,改善肠源性内毒素血症,对肠黏膜屏障起到保护作用,可作为慢性肝病的辅助治疗。     

布拉酵母对小儿重症肺炎患儿肠黏膜屏障功能的影响

目的 探讨布拉酵母对小儿重症肺炎患儿肠黏膜屏障功能的影响。方法 将90例重症肺炎患儿按随机数字表分为对照组和观察组各45例。对照组患儿采用常规治疗,观察组患儿在常规治疗的同时加用布拉酵母治疗1周。比较两组患儿治疗前后血浆Ｄ-乳酸及肠型脂肪酸结合蛋白变化情况、胃肠功能障碍及腹泻发生率以及患儿不良反应。结果 治疗1周后,两组患儿血浆D-乳酸和肠型脂肪酸结合蛋白水平均低于治疗前（均P<0.01）,且不同时间点观察组指标水平下降幅度大于对照组（均P<0.01）。观察组患儿胃肠功能障碍发生率为6.7％、对照组为22.2％;观察组患儿腹泻发生率为15.6%,对照组为33.3%,二者比较差异均有统计学意义（均P<0.05）。观察组患儿无药物不良反应发生。结论 布拉酵母对重症肺炎患儿肠黏膜屏障具有保护作用,能减少胃肠功能障碍及腹泻发生率。     

肠内营养支持治疗对炎症性肠病患者肠黏膜屏障功能及炎症反应的影响

目的 探讨早期肠内营养（EN）支持治疗对炎症性肠病（IBD）患者肠黏膜屏障功能及炎症反应的影响。方法 将80例IBD患者按营养支持治疗途径分为EN组（48例）和肠外营养（PN）组（32例）,在常规治疗的基础上分别给予早期EN、PN支持治疗。比较治疗前后2组患者营养学相关指标[白蛋白（ALB）、前白蛋白（PA）、转铁蛋白（TF）]、肠黏膜屏障功能指标（内毒素、D-乳酸）及炎症相关指标[C-反应蛋白（CRP）、降钙素原（PCT）、粪便钙卫蛋白（FCP）]水平。结果 治疗前,2组患者各观察指标水平差异无统计学意义（P>0.05）;治疗后,与治疗前相比,2组患者血清ALB、PA及TF水平均显著升高（P0.05）。结论 在常规治疗的基础上,早期EN支持治疗对IBD患者肠黏膜屏障功能的改善及炎症缓解作用优于PN支持治疗。     

Increased Expression of Apolipoprotein D Following Experimental Traumatic Brain Injury

Increasing evidence suggests that apolipoprotein D (apoD) could play a major role in mediating neuronal degeneration and regeneration in the CNS and the PNS. To investigate further the temporal pattern of apoD expression after experimental traumatic brain injury in the rat, male Sprague-Dawley rats were subjected to unilateral cortical impact injury. The animals were killed and examined for apoD mRNA and protein expression and for immunohistological analysis at intervals from 15 min to 14 days after injury. Increased apoD mRNA and protein levels were seen in the cortex and hippocampus ipsilateral to the injury site from 48 h to 14 days after the trauma. Immunohistological investigation demonstrated a differential pattern of apoD expression in the cortex and hippocampus, respectively: Increased apoD immunoreactivity in glial cells was detected from 2 to 3 days after the injury in cortex and hippocampus. In contrast, increased expression of apoD was seen in cortical and hippocampal neurons at later time points following impact injury. Concurrent histopathological examination using hematoxylin and eosin demonstrated dark, shrunken neurons in the cortex ipsilateral to the injury site. In contrast, no evidence of cell death was observed in the hippocampus ipsilateral to the injury site up to 14 days after the trauma. No evidence of increased apoD mRNA or protein expression or neuronal pathology by hematoxylin and eosin staining was detected in the contralateral cortex and hippocampus. Our results reveal induction of apoD expression in the cortex and hippocampus following traumatic brain injury in the rat. Our data also suggest that increased apoD expression may play an important role in cortical neuronal degeneration after brain injury in vivo. However, increased expression of apoD in the hippocampus may not necessarily be indicative of neuronal death.     

Energy Metabolic Changes in the Early Post-injury Period Following Traumatic Brain Injury in Rats

Impaired cerebral energy metabolism may be a major contributor to the secondary injury cascade that occurs following traumatic brain injury (TBI). To estimate the cortical energy metabolic state following mild and severe controlled cortical contusion (CCC) TBI in rats, ipsi-and contralateral cortical tissues were frozen in situ at 15 and 40 min post-injury and adenylate (ATP, ADP, AMP) levels were analyzed using high-performance liquid chromatography (HPLC) and the energy charge (EC) was calculated. At 15 min post-injury, mildly brain-injured animals showed a 43% decrease in cortical ATP levels and a 2.4-fold increase in AMP levels (P < 0.05), and there was a significant reduction of the ipsilateral cortical EC when compared to sham-injured animals (P < 0.05). At 40 min post-injury, the ipsilateral adenylate levels and EC had recovered to the values observed in the sham-injury group. In the severe CCC group, there was a 51% decrease in ipsilateral cortical ATP levels and a 5.3-fold increase in AMP levels with a significant reduction of cortical EC at 15 min post-injury (P < 0.05). At 40 min post-injury, a 2.6-fold ipsilateral increase in AMP levels and an 11% and 44% decrease in EC and ATP levels, respectively, remained (P < 0.05). A 37–38% reduction of the total adenylate pool was observed ipsilaterally in both CCC severity groups at the early time-point, and a 19% and 28% decrease remained in the mild and severe CCC groups, respectively, at 40 min post-injury. Significant contralateral ATP and EC changes were only observed in the severe CCC group at 40 min post-injury (P < 0.05). The energy-requiring secondary injury cascades that occur early post-injury do not challenge the brain tissue to the extent of ATP depletion and may provide a window of opportunity for therapeutic intervention.     

Stretch in Brain Microvascular Endothelial Cells (cEND) as an In Vitro Traumatic Brain Injury Model of the Blood Brain Barrier

Due to the high mortality incident brought about by traumatic brain injury (TBI), methods that would enable one to better understand the underlying mechanisms involved in it are useful for treatment. There are both in vivo and in vitro methods available for this purpose. In vivo models can mimic actual head injury as it occurs during TBI. However, in vivo techniques may not be exploited for studies at the cell physiology level. Hence, in vitro methods are more advantageous for this purpose since they provide easier access to the cells and the extracellular environment for manipulation.Our protocol presents an in vitro model of TBI using stretch injury in brain microvascular endothelial cells. It utilizes pressure applied to the cells cultured in flexible-bottomed wells. The pressure applied may easily be controlled and can produce injury that ranges from low to severe. The murine brain microvascular endothelial cells (cEND) generated in our laboratory is a well-suited model for the blood brain barrier (BBB) thus providing an advantage to other systems that employ a similar technique. In addition, due to the simplicity of the method, experimental set-ups are easily duplicated. Thus, this model can be used in studying the cellular and molecular mechanisms involved in TBI at the BBB.     

Foxj1 在脑外伤后的表达变化

目的:探讨脑外伤后Foxj1在脑组织中的表达变化及其意义。方法:建立大鼠脑外伤模型,利用Western blot和免疫组织化学方法检测脑外伤后Foxj1在脑组织中表达的变化。结果:Western blot显示大鼠脑外伤后,Foxj1的表达逐步增高,伤后3 d升至最高点,之后逐渐降低;免疫组织化学的结果与Western blot一致。结论:脑外伤后Foxj1在脑组织中的表达增高,这种增高的表达参与了脑外伤后脑组织的病理生理和生化变化。     

急诊绿色通道提高颅脑外伤患者救治效果的体会

目的:评价建立急诊绿色通道对救治颅脑外伤患者的价值.方法:采用回顾性分析方法,收集我院2007年1月～2012年1月救治的颅脑外伤患者199例,其中急诊绿色通道组111例(A组)和非急诊绿色通道组88例(B组)的救治情况进行比较,分析两组救治的疗效、死亡率及预后.结果:199例颅脑外伤患者中,绿色通道组(A组)111例(55.78％),死亡26例(23.42％),对照组88例(44.22％),死亡30例(34.09％).A组的有效治疗时间较B组明显缩短,差异有统计学意义(0.01＜P＜0.05);A组硬膜外血肿(33例)的术前血肿量少于B组(30例),预后较B组好,差异有统计学意义(0.01＜P＜0.05);A组的中重型颅脑外伤的死亡率明显低于B组,差异有统计学意义(0.01＜P＜0.05),两组特重性颅脑外伤的死亡率仍较高,差异无统计学意义(P＞0.05).结论:急诊绿色通道可缩短颅脑外伤患者救治等待时间,改善中重型颅脑外伤患者的预后.     

Alterations in Ionized and Total Blood Magnesium After Experimental Traumatic Brain Injury

Experimental evidence suggests that magnesium plays a role in the pathophysiological sequelae of brain injury. The present study examined the variation of blood ionized and total magnesium, as well as potassium, sodium, and ionized calcium, after experimental fluid percussion brain injury in rats. Blood ionized magnesium concentration significantly declined from 0.45 +/- 0.02 to 0.32 +/- 0.02 mM by 30 min postinjury and stayed depressed for the 24-h study period in vehicle-treated rats. Blood total magnesium concentration was 0.59 +/- 0.01 mM and remained stable over time in brain-injured vehicle-treated animals. When magnesium chloride (125 micromol/rat) was administered 1 h postinjury, ionized magnesium levels were restored by 2 h postinjury and remained at normal values up to 24 h following brain trauma. Magnesium treatment also significantly reduced posttraumatic neuromotor impairments 1 and 2 weeks after the insult, but failed to attenuate spatial learning deficits. A significant positive and linear correlation could be established between ionized magnesium levels measured 24 h postinjury and neuromotor outcome at 1 and 2 weeks. We conclude that acute ionized magnesium measurement may be a predictor of long-term neurobehavioral outcome following head injury and that delayed administration of magnesium chloride can restore blood magnesium concentration and attenuate neurological motor deficits in brain-injured rats.     

μ-Calpain Activation and Calpain-Mediated Cytoskeletal Proteolysis Following Traumatic Brain Injury

Abstract: Increasing evidence suggests that excessive activation of the calcium-activated neutral protease μ-calpain could play a major role in calcium-mediated neuronal degeneration after acute brain injuries. To further investigate the changes of the in vivo activity of μ-calpain after unilateral cortical impact injury in vivo, the ratio of the 76-kDa activated isoform of μ-calpain to its 80-kDa precursor was measured by western blotting. This μ-calpain activation ratio increased to threefold in the pellet of cortical samples ipsilateral to the injury site at 15 min, 1 h, 3 h, and 6 h after injury and returned to control levels at 24–48 h after injury. We also investigated the effect of μ-calpain activation on proteolysis of the neuronal cytoskeletal protein α-spectrin. Immunoreactivity for α-spectrin breakdown products was detectable within 15 min after injury in cortical samples ipsilateral to the injury site. The levels of α-spectrin breakdown products increased in a biphasic manner, with a large increase between 15 min and 6 h after injury, followed by a smaller increase between 6 and 24 h after the insult. No further accumulation of α-spectrin breakdown products was observed between 24 and 48 h after injury. Histopathological examinations using hematoxylin and eosin staining demonstrated dark, shrunken neurons within 15 min after traumatic brain injury. No evidence of μ-calpain autolysis, calpain-mediated α-spectrin degradation, or hematoxylin and eosin neuronal pathology was detected in the contralateral cortex. Although μ-calpain autolysis and cytoskeletal proteolysis occurred concurrently with early morphological alterations, evidence of calpain-mediated proteolysis preceded the full expression of evolutionary histopathological changes. Our results indicate that rapid and persistent μ-calpain activation plays an important role in cortical neuronal degeneration after traumatic brain injury. Our data also suggest that specific inhibitors of calpain could be potential therapeutic agents for the treatment of traumatic brain injury in vivo.     

Genetic Influences on Outcome Following Traumatic Brain Injury

Several genes have been implicated as influencing the outcome following traumatic brain injury (TBI). Currently the most extensively studied gene has been APOE. APOE can influence overall and rehabilitation outcome, coma recovery, risk of posttraumatic seizures, as well as cognitive and behavioral functions following TBI. Pathologically, APOE is associated with increased amyloid deposition, amyloid angiopathy, larger intracranial hematomas and more severe contusional injury. The proposed mechanism by which APOE affects the clinciopathological consequences of TBI is multifactorial and includes amyloid deposition, disruption of cytoskeletal stability, cholinergic dysfunction, oxidative stress, neuroprotection and central nervous system plasticity in response to injury. Other putative genes have been less extensively studied and require replication of the clinical findings. The COMT and DRD2 genes may influence dopamine dependent cognitive processes such as executive/frontal lobe functions. Inflammation which is a prominent component in the pathophysiological cascade initiated by TBI, is in part is mediated by the interleukin genes, while apoptosis that occurs as a consequence of TBI may be modulated by polymorphisms of the p53 gene. The ACE gene may affect TBI outcome via mechanisms of cerebral blood flow and/or autoregulation and the CACNA1A gene may exert an influence via the calcium channel and its effect on delayed cerebral edema. Although several potential genes that may influence outcome following TBI have been identified, future investigations are needed to validate these genetic studies and identify new genes that might influence outcome following TBI. Special issue dedicated to John P. Blass.     

丙泊酚镇静对颅脑损伤患者脑氧供需平衡的影响

目的:探讨丙泊酚实施不同程度镇静对颅脑损伤患者脑氧供需平衡的影响。方法:选择急性闭合性颅脑损伤需行机械通气患者46例,随机分为轻度镇静组(A组),设定目标脑电双频谱指数(BIS)值75%;中度镇静组(B组),设定目标BIS值65%。主要观察达设定目标BIS值时丙泊酚靶控输注(TCI)浓度、Ramsay镇静评分、脑氧供需平衡指标颈内静脉血氧饱和度(SjvO_2)和脑氧摄取率(CERO_2)以及心率(HR)、平均动脉压(MAP)。结果:两组设定镇静目标需丙泊酚TCI浓度有明显差异(P0.05),但Ramsay评分比较差异无统计学意义;中度镇静组SjvO_2较基础值增加约12%(P0.05),CERO_2较基础值下降约15%(P0.05);而轻度镇静组对SjvO_2和CERO_2基础值没有影响。两组HR均较基础值减慢(P0.05),但对MAP均没有影响。结论:颅脑损伤患者维持目标镇静BIS值65%,调控丙泊酚靶浓度1.5-1.6μg/mL,更有利于改善脑氧供需平衡。