川芎嗪对急性脑梗塞患者超氧化物歧化酶含量的影响

对25例急性脑梗塞患者和22例健康人铜锌超氧化物歧化酶(CuZnSOD)含量测定结果分别为155.17±40.18ng/L和230.95±30.81ng/L。说明急性脑梗塞组CuZnSOD含量明显低于健康人组(P<0.001)。急性脑梗塞患者又随机分为低分子右旋糖酐(低右)治疗组和低右加川芎嗪(川芎嗪)治疗组,低右组治疗前后CuZnSOD含量分別为151.99±38.74ng/L和185.67±45.46ng/L(P>0.05),川芎嗪组治疗前后CuZnSOD含量分别为158.00±41.23ng/L和207.21±40.05ng/L(P<0.01)。提示川芎嗪可增加脑梗塞患者CuZnSOD含量,清除氧自由基,减轻脂质过氧化损伤。     

非洛地平对高血压患者脂质过氧化损害的影响

目的:探讨脂质过氧化损害与高血压患者病情之间的关系,并通过非洛地平干预降低高血压的脂质过氧化损害。方法:通过测定高血压患者外周血中超氧化物歧化酶(superoxidedis-mutase,SOD)、丙二醛、谷胱甘肽过氧化物酶(glutathioneperoxidase,GSH-Px)、过氧化脂质(lipideoxide,LPO),并用非洛地平治疗4周后,观察治疗前后的变化。结果:发现3级高血压患者血中S0D,GSH-Px活性分别为(1.10±0.20)kat/L,(0.21±0.13)kat/g,明显低于2级高血压;而丙二醛、LPO分别为(6.98±1.71)nmol/L,(13.68±6.55)μmol/L,高于2级高血压组;经治疗后SOD,GHs-Px的升高和LPO,丙二醛的降低,较治疗前差异均有显著性(t=3.181,P<0.01;t=3.057,P<0.01)。结论:高血压患者存在严重的氧化反应病理亢进及抗氧化能力减低现象。非洛地平可有效对抗氧自由基,提高机体抗氧化能力,减少脂质过氧化作用,其机制可能是通过保护内皮细胞氧化,防止内皮细胞分泌失衡,起着保护性作用。     

川芎嗪对心肺复苏后脑缺血-再灌注损伤的保护作用

目的 :观察川芎嗪对心肺复苏后对脑损伤的保护作用及其机制。方法 :将 4 2例需行心肺复苏患者按随机数表法分为治疗组 (A组 )与对照组 (B组 )。 A组 2 2例在心肺复苏开始同时给予川芎嗪 2 4 0 mg加质量分数为 5 %的葡萄糖 2 5 0 ml中静脉滴注 ,1h滴完 ,其后按上述剂量每日 1次 ,连用 7d。B组除不用川芎嗪外 ,其他治疗同 A组。检测两种治疗方法对患者血中超氧化物歧化酶 (SOD)、丙二醛 (MDA)、血栓素 B2 (TXB2 )的影响 ;并以意识恢复为主要指标评定临床疗效。结果 :A组显效 16例 (72 .72 % ) ,有效 3例 (13.6 4 % ) ,无效 3例(13.6 4 % ) ;B组显效 8例 (40 .0 0 % ) ,有效 3例 (15 .0 0 % ) ,无效 9例 (45 .0 0 % ) ,两组之间差异显著 (P<0 .0 5 )。两组治疗后静脉血 SOD、MDA和 TXB2 均有改善 ,但 A组改善程度明显优于 B组 (P均 <0 .0 1)。结论 :川芎嗪能对抗脂质过氧化 ,提高 SOD活性 ,抑制血小板活化 ,对心肺复苏后脑缺血再灌注损伤有一定的保护作用 ,早期应用可提高脑复苏成功率。     

复方丹参对脑梗死患者神经功能缺损程度及自由基的影响

背景脑梗死有多种发病机制,自由基及其脂质过氧化作用参与了动脉粥样硬化和脑缺血后神经细胞的损害过程.复方丹参是一种临床上常用的治疗脑梗死和冠心病的活血化瘀中药,其作用机制还有许多不明之处.目的观察复方丹参对脑梗死患者神经功能缺损程度及自由基的影响,并探讨其可能作用机制.设计随机对照研究.单位一所大学医院的神经内科.对象2002-02/12锦州医学院附属第一医院神经内科住院患者538例,其诊断符合第四届全国脑血管病学术会议通过的"各类脑血管疾病诊断要点",均经脑CT扫描确诊,均为发病在72 h以内的首次发病的动脉粥样硬化性脑梗死患者.排除伴有心肌梗死、心力衰竭、心房颤动,肝肾功能不全,消化道出血,血管性痴呆和延髓麻痹以及中途不合作者.符合上述标准的患者为68例,其中男38例,女30例;年龄52～78岁,平均(64.62±5.80)岁.入选病例按先后顺序和对照组自愿原则采用抽签法随机分成研究组和对照组.方法两组基础治疗相同,研究组在此基础上加用复方丹参注射液,加入生理盐水250mL中静脉注射,1次/d,连用14 d为1个疗程;对照组应用血栓通注射液15 mL,加入生理盐水250 mL中静脉注射,1次/d,连用14 d为1个疗程.主要观察指标①临床神经功能缺损程度评分.②临床疗效评定.③血清脂质过氧化物(lipoperoxide,LPO)水平和超氧化物歧化酶(superoxide dismutase,SOD)活性的测定.结果两组治疗后神经功能缺损程度评分的减少经自身对照均具有统计学差异(研究组28.62±6.76比13.84±8.16和对照组28.58±7.05比21.52±8.24,t=8.134和t=3.796,P＜0.001),而研究组评分的减少更明显,与对照组治疗后比较差异有非常显著性意义(t=3.861,P＜0.001);复方丹参治疗脑梗死的有效率为88.24%,显著优于对照组(67.65%)(x2=4.19,P＜0.05);复方丹参能使患者血清的LPO水平[(8.69±1.28)nmol/L比(5.86±1.42)nmol/L,t=8.628,P＜0.001]明显降低,与对照组治疗后相比亦具有统计学差异[(5.86±1.42)nmol/L比(8.56±0.95)nmol/L,t=9.125,P＜0.001];同时显著升高血清的SOD活性[(26.25±4.64)mkat/g比(30.01±3.87)mkat/g,t=3.629,P＜0.001],与对照组治疗后相比亦具有统计学差异[(30.01±3.87)mkat/g比(26.33±4.14)mkat/g,t=3.778,P＜0.001 ].结论复方丹参能显著改善脑梗死患者的神经功能缺损程度,治疗脑梗死疗效确切;能降低脑梗死患者血清LPO含量,升高血清SOD活性.推测清除自由基和抗脂质过氧化损伤可能是其重要的机制之一,为其在临床上治疗脑梗死提供了进一步的理论依据.     

补脾益智三方对衰老大鼠脂质过氧化反应的影响

目的:分析补脾益智三方对衰老大鼠脂质过氧化反应的影响,探讨其延缓衰老的作用机制。方法:对青年(2月龄)及老年(22月龄)大白鼠进行造模,分别为脾气虚、脾阳虚及脾阴虚证,用补益脾气、温运脾阳和滋补脾阴方药预防治疗,观察血浆脂质过氧化物(lipidperoxidation,LPO)、血浆超氧化物歧化酶(superoxidedismutase,SOD)活性及血浆脂褐质(lipofuscin,LPF)含量的变化及其与脾虚衰老的关系。结果:伴随增龄,机体血浆LPO含量明显升高犤青年正常对照组为(13.7250±0.7250)μmol/L,老年正常对照组为(18.4800±1.6191)μmol/L,P<0.05犦,SOD活性明显降低犤青年正常对照组为(0.7065±0.0531)μmol/L,老年正常对照组为(0.5662±0.0577)μmol/L,P<0.05犦,LPF含量明显升高犤青年正常对照组为(11.3038±2.3553)μmol/L,老年正常对照组为(24.1050±3.1955)μmol/L,P<0.05犦,补益脾胃方药可以降低不同证型脾虚证老年大鼠的LPO含量。补益脾胃方药可以提高不同证型脾虚证老年大鼠的SOD活性。补益脾胃方药可以降低不同证型脾虚证老年大鼠的LPF含量。其中老年脾气虚证治疗组LPF含量降低不显著。结论:脂质过氧化反应增强是脾虚衰老的病理反应之一,补益脾胃方药能提高机体抗氧化能力,因而能降低脾虚衰老的过氧化损伤,从而起到延缓衰老     

银杏叶制剂对正常脑温脑缺血大鼠的脑保护作用

背景在银杏叶提取物治疗脑缺血的实验研究中,由于使用全身麻醉药物,有可能诱导脑温改变,影响实验结果准确性.目的研究常温状态下,国产银杏叶提取物对脑缺血再灌注组织抗氧化酶、脂质过氧化物及脑缺血组织含水量的影响.设计随机对照的实验研究.地点和材料实验在华中科技大学同济医学院完成.取24只Wistar大鼠,体质量为250～300 g,将实验大鼠随机分为假手术组(n=8)、脑缺血对照组(n=8)、脑缺血银杏叶提取物治疗组(n=8),对照组及治疗组参考Nagasawa方法,制备正常脑温大鼠左侧大脑中动脉缺血2 h再灌注2 h动物模型,进行对照研究.干预实验大鼠的脑温用颞肌温度反映,将测温探头包埋入大鼠左侧颞肌深部贴近骨外膜,用半导体氧化物温度传感器连续监测.用60 W白炽灯头部加温和自动双控颅脑降温仪调节脑温,使脑温维持在常温(36.5～37℃)水平.按设计方案制备正常脑温大鼠脑缺血再灌注损伤模型,脑缺血银杏叶提取物治疗组大鼠在手术前12,8,4 h和脑缺血及再灌注即刻,分别腹腔内注射银杏叶提取物注射液,每次3 mL,共5次.脑缺血对照组及假手术组大鼠腹腔内注射相同次数和剂量的生理盐水.主要观察指标脑缺血组织超氧化物歧化酶、谷胱甘肽过氧化物酶、还原型谷胱甘肽、丙二醛含量及脑缺血组织含水量.结果脑缺血对照组超氧化物歧化酶,谷胱甘肽过氧化物酶,还原型谷胱甘肽水平分别为(73.35±12.86)NU/mg,(167.37±54.34)μkat/g,(196.84±22.75)μg/g,明显低于假手术组的(96.02±16.83)NU/mg,(338.57±84.02)μkat/g,(337.51±34.89)μg/g(P＜0.01或P＜0.05);脑缺血银杏叶提取物治疗组超氧化物歧化酶,谷胱甘肽过氧化物酶,还原型谷胱甘肽水平分别为(87.24±15.03)NU/mg,(316.56±93.52)μkat/g,(263.16±28.54)μg/g,明显高于脑缺血对照组(P＜0.01或P＜0.05).脑缺血对照组丙二醛水平为(308.34±26.81)nmol/g,明显高于假手术组的(101.46±10.97)nmol/g(P＜0.01);脑缺血银杏叶提取物治疗组丙二醛水平为(125.86±13.90)nmol/g,明显低于脑缺血对照组(P＜0.01).脑缺血对照组脑缺血组织含水量为(80.45±0.44)%,明显高于假手术组的(78.20±0.25)%(P＜0.01);脑缺血银杏叶提取物治疗组脑缺血组织含水量为(79.63±0.46)%,明显低于脑缺血对照组(P＜0.05).结论正常脑温状态下,国产银杏叶提取物能抑制脑缺血时自由基的过多产生和脂质过氧化反应,减轻脑水肿和血脑屏障破坏,保护脑缺血组织.     

慢性阻塞性肺病患者血清TXB2、6-K-PGF1α、PGE2测定及其临床意义

目的探讨慢性阻塞性肺病(COPD)患者血清血栓素B2(TXB2)、6-酮-前列腺素F1α(6-K-PGF1α)、前列腺素E2(PGE2)水平的改变及其临床意义.方法采用放射免疫法测定54例COPD患者和40例健康对照组的血清TXB2、6-K-PGF1α、PGE2水平,进行对照统计分析.结果COPD组血清TXB2水平显著高于对照组(99.65±16.16ng/L VS 50.33±6.03ng/L;t=2.222,P＜0.05),6-K-PGF1α水平显著低于对照组(48.53+5.90ng/L VS 79.16±8.93ng/L;t=2.963,P＜0.01),6-K-PGF1α PGE2两者间呈显著正相关(r=0.232,P＜0.05).伴有呼吸衰竭组血清PGE2显著高于无呼衰组(12.79±1.76ng/L VS 6.99±1.15ng/L;t=2.353,P＜0.05),但血清TXB2、6-K-PGF1α无显著差异(P＞0.05).死亡组与出院好转组血清TXB2、6-K-PGF1α、PGE2水平均无显著差异(t=0.438,t=0.721,t=0.556,P均＞0.05).结论COPD组血清TXB2水平显著增高,6-K-PGF1α水平显著降低,且6-K-PGF1α与PGE2间呈显著正相关,伴有呼吸衰竭组血清PGE2显著高于无呼衰组,提示COPD患者中存在血液高凝状态及血管痉挛,抗凝与扩血管治疗有助于延缓COPD进展.     

以压灸百会穴为主治疗对椎动脉型颈椎病患者血栓素A2和前列环素的影响

目的探讨压灸百会穴为主治疗椎动脉型颈椎病(CSA)的疗效.方法采用随机单盲对照法将广州中医药大学收治的34例椎动脉型颈椎病患者分为两组,其中治疗组17例,予以压灸百会穴及局部电针法,对照组17例,采用单纯局部电针法,观察其临床疗效,并测定其治疗前后血浆血栓烷B2(TXB2)、6-酮前列腺素F1α(6-keto-PGF1-α)含量变化及K/T值.结果治疗组痊愈9例,显效6例,好转2例,无效0例;对照组痊愈4例,显效6例,好转5例,无效2例.治疗组血栓烷B2、6-酮前列腺素F1α治疗前的值分别为(442.96±164.11),(157.01±75.43)ng/L治疗后为(144.22±127.81),(368.85±117.09)ng/L,对照组治疗前、后分别为(383.25±210.75),(156.39±84.15)ng/L和(198.72±141.65),(258.78±85.25)ng/L,两组与治疗前相比,差异有显著性意义(t=-4.01,-3.2,5.92,6.27,P＜0.01),治疗组治疗后与对照组相比差异也有显著性意义(t=-2.19,3.13,P＜0.01).结论压灸百会为主能有效改善椎动脉型颈椎病患者的临床症状,起到舒张血管压力的作用.     

黄芪注射液对高血压病患者血浆P选择素、血栓素B2及6酮前列环素F1α的影响

目的观察黄芪注射液对高血压病(EH)患者血浆P选择素(P-sel)、血栓素B2 (TXB2)和6酮前列环素F1α(6-Keto-PGF1α)的影响.方法采用平行随机对照区组设计,EH患者138例,随机分为2组(黄芪组及常规治疗组);对照组为健康查体人员66例.放射免疫分析法测定各组中血浆P-sel、TXB2、6-Keto-PGF1α的含量.黄芪组常规降压加黄芪注射液治疗14天后测定上述指标;常规治疗组患者经常规降压治疗14天后同时测定上述指标. 结果 EH患者与健康对照组比较血浆P-sel 升高,TXB2升高(P<0.01),6-Keto-PGF1α降低(P<0.05) .黄芪注射液治疗后EH患者血浆P-sel 降低 (13.21±3.47 比 9.14±4.09) μg/L,TXB2下降(281.7±56.3 比 245.4±59.7) ng/L,6-Keto-PGF1α上升(25.1±5.3 比 30.3±6.9) ng/L(P均<0.01).结论黄芪注射液可在较短治疗周期内改善EH患者血小板功能.     

银杏叶提取物对兔冷冻伤脑水肿的保护作用及其机制

背景冷冻所致脑水肿,被认为是一种典型的血管源性脑水肿.许多化学递质参与这一过程,其中氧自由基起主导作用,采用银杏叶提取物所具有的氧自由基清除剂作用 ,可望发挥抗脑水肿及脑保护作用. 目的 探讨银杏叶提取物对冷冻所致兔脑水肿的保护作用及其机制. 设计采用完全随机设计,空白对照实验. 地点和材料同济医科大学附属同济医院神经外科,材料由同济医科大学动物中心提供.健康中国家兔 30只,体重 2.0～ 2.8 kg,雌雄不拘 . 干预 30只健康中国家兔,单纯随机分为 3组对照组、脑水肿模型组、 EGb761处理组, 3组家兔分别在术后 6,24 h断头取脑测定脑组织含水量、脂质过氧化物含量及超氧化物歧化酶活性. 主要观察指标测定脑含水量,脑组织 LPO含量及 SOD活力的变化. 结果术后 6 h和 24 h,脑水肿模型组脑组织 LPO含量 [(6.82± 1.36) μ mol/L,(7.95± 2.12) μ mol/L]及脑组织含水量 [(78.56± 0.61) % ;( 79.86± 0.54) % ]呈进行性增高, SOD活性则呈进行性下降 (P< 0.05); EGb761处理组脑组织 LPO含量及脑组织含水量增加不显著,且 SOD活性回升( P< 0.05). 结论 EGb761具有抗脑水肿和保护脑组织的作用.而其减轻脂质过氧化反应,保护脑组织内源性 SOD活性,增强脑组织自身清除氧自由基的功能,则可能是其重要的药理作用机制之一.     

Guns and Knives in New Mexico: Patterns of Penetrating Trauma, 1978–1993

Objective: To identify patterns of nonfatal and fatal penetrating trauma among children and adults in New Mexico using ED and medical examiner data.
Methods: The authors retrospectively sampled in 5-year intervals all victims of penetrating trauma who presented to either the state Level-1 trauma center or the state medical examiner from a 16-year period (1978–1993). Rates of nonfatal and fatal firearm and stabbing injury were compared for children and adults.
Results: Rates of nonfatal injury were similar (firearm, 34.3 per 100,000 person-years; stabbing, 35.1). However, rates of fatal injury were significantly different (firearm, 21.9; stabbing, 2.7; relative risk: 8.2; 95% confidence interval: 5.4, 12.5). From 1978 to 1993, nonfatal injury rates increased for children (p = 0.0043) and adults (p < 0.0001), while fatal penetrating injury remained constant. The increase in nonfatal injury in children resulted from increased firearm injury rates. In adults, both stabbing and firearm nonfatal injury rates increased.
Conclusions: Nonfatal injury data suggest that nonfatal violence has increased; fatal injury data suggest that violent death rates have remained constant. Injury patterns vary by age, mechanism of trauma, and data source. These results suggest that ED and medical examiner data differ and that both are needed to guide injury prevention programs.     

Interprofessional approaches to creating safe,high quality health care

Three supplementary perspectives are presented arguing that interprofessional collaboration is both necessary and desirable. Nonetheless, there are often too many serious intra-professional barriers and obstacles to interprofessional collaboration to make it successful. Some of these barriers, it is argued and illustrated, are found in the multiple ways in which professional identity is tacitly acquired and embodied in the practitioners' habitual, everyday practice. The paper then explores ways in which reflection, especially Second order reflection, can help to elucidate and overcome these obstacles, as well as increasing professional adaptability and competence.     

Systematic Reviews Published in the January 2011 Issue of The Cochrane Library

ABSTRACT

The Cochrane Library of Systematic Reviews is published quarterly as a DVD and monthly online. The January 2011 issue (first quarterly DVD for 2011) contains 4515 complete reviews, 1985 protocols for reviews in production, and 13,521 one-page summaries of systematic reviews published in the general medical literature. In addition, there are citations of 641,000 randomized controlled trials, and 14,018 cited papers in the Cochrane methodology register. The health technology assessment database contains over 9300 citations. One hundred and seven new reviews have been published in the last 3 months, of which five have potential relevance for practitioners in pain and palliative medicine.     

Prise en charge des entorses externes de cheville : étude clinique préliminaire sur l’efficacité du dispositif Myolux™

Ankle sprains are the most common injury of the musculoskeletal system and are associated with significant societal and economic impacts. It has been proven that classical therapeutic strategies may not be effective in preventing recurrent injuries: the recurrence rates reported in the literature can reach 73%. In order to provide an effective rehabilitation solution, a destabilizing orthosis was developed. This device is equipped with a mechanical articulator reproducing the subtalar mechanics and placed under the heel. In this paper, we present the main results of a preliminary clinical study conducted between 2004 and 2007. All subjects included in this study were treated with the abovementioned orthosis during 10 rehabilitation sessions of 30 minutes each. Data show a relatively low recurrence rate of 12% for the overall population. Moreover, it's of primary importance to note that this satisfactory ratio is largely reduced (3% of recurrence rate) for the 29 patients who performed one training session per month after the 10th initial rehabilitation sessions. Hence, the destabilizing orthosis appears to be an effective solution to prevent recurrent ankle sprains. However, joint protection requires long-term and regular training sessions. This result has motivated the development of a similar device allowing patients to perform training sessions at home. Finally, data obtained in this study are promising awaiting the final results of the comparative, multicentric and independent clinical trials currently managed by the Hospices Civils de Lyon.     

Clinical Trial Updates and Hotline Sessions presented at the European Society of Cardiology Congress 2007

This article provides information and commentaries on trials which were presented at the Hotline and Clinical Trial Update Sessions at the European Society of Cardiology Congress 2007 in Vienna. The key presentations were performed by leading experts in the field with relevant positions in the trials or registries. It is important to note that unpublished reports should be considered as preliminary data, as the analysis may change in the final publications. The comprehensive summaries have been generated from the oral presentation and the webcasts of the European Society of Cardiology and should provide the readers with the most comprehensive information of relevant publications.     

Prospects for the control of neglected tropical diseases by mass drug administration

The prospects for the control of neglected tropical diseases, including soil-transmitted helminthiasis, shistosomiasis, lymphatic filariasis, onchocerciasis and trachoma, through mass drug administration, are exemplified by the elimination of the trachoma as a public-health problem in Morocco. In spite of this and other striking successes, mass drug administration programs are faced with major challenges resulting from suboptimal coverage and lack of efficacy. At current suboptimal coverage rates, programs may need prolongation for an extended period, increasing costs and undermining sustainability. Community participation through health education and information appears to be crucial to improve coverage and to achieve sustainability. Implementation of complementary measures, such as vector control, improved hygiene and environmental sanitation, are important to further control transmission and to prevent re-emergence of the infection and, again, may only be achieved effectively through community-based initiatives. To reduce costs and to relieve pressure on the health system, combining neglected tropical disease programs in areas where diseases coexist and integration with existing control programs for malaria, tuberculosis and HIV/AIDS is advocated. The risk of developing drug resistance is of particular concern in view of the lack of alternative drugs, and reduced treatment efficacy due to emerging resistance is evident for the soil-transmitted helminths and onchocerciasis. Given the risk for the development of drug resistance and the need for a high degree of participation, close attention should be paid to the monitoring of the coverage and efficacy of the different program components.     

Balance and Boundaries in Grief Counseling: An Intervention Framework for Volunteer Training

Volunteers or paraprofessional counselors are commonly used to provide supportive care to the bereaved. These counselors generally are trained in basic listening skills, providing a generic, nonspecific approach to intervention that remains to be proven effective. The present paper outlines a framework that provides paraprofessionals with a broader model for intervention with the bereaved. Attention to boundaries as a helper and balance in the grief recovery are central to the model. Interventions are described that provide the paraprofessional counselor with more options for tailoring their counseling strategy to the individual. These include techniques that are presumed to be more specific to the enhancement of grief recovery.     

A new method for the simultaneous analysis of unmodified and modified urinary nucleosides and nucleobases by high performance liquid chromatography

Details are given of a new, rapid and simple pre-fractionation method and an isocratic high performance liquid chromatography system suitable for parallel analysis of nucleosides and nucleobases from urine and other biological fluids. The quantitative recovery and excellent reproducibility of the method is demonstrated by analysis of representative standard RNA catabolites. The advantage of this new method for application to biological samples is discussed.     

Bacterial meningitis: an update of new treatment options

The outcome of bacterial meningitis critically depends on the rapid initiation of bactericidal antibiotic therapy and adequate management of septic shock. In community-acquired meningitis, the choice of an optimum initial empirical antibiotic regimen depends on the regional resistance patterns. Pathogens resistant to antibacterials prevail in nosocomial bacterial meningitis. Dexamethasone is recommended as adjunctive therapy for community-acquired meningitis in developed countries. In comatose patients, aggressive measures to lower intracranial pressure <20 mmHg (in particular, external ventriculostomy, osmotherapy and temporary hyperventilation) were effective in a case–control study. Although many experimental approaches were protective in animal models, none of them has been proven effective in patients. Antibiotics, which are bactericidal but do not lyse bacteria, and inhibitors of matrix metalloproteinases or complement factor C5 appear the most promising therapeutic options. At present, vaccination is the most efficient method to reduce disease burden. Palmitoylethanolamide appears promising to enhance the resistance of the brain to infections.