The mechanism of hepatic graft protection against reperfusion injury by prostaglandin E1

1 (PGE₁) on protecting against hepatic endothelial cell damage and increasing graft viability after cold preservation and reperfusion, using an isolated perfused rat liver (IPRL) model. The grafts were divided into three groups, according to the cold preservation time and PGE₁ administration, namely: 4 h preservation (group 1, n = 9), 6 h preservation (group 2, n = 9), and 6 h preservation followed by PGE₁ infusion (group 3, n = 9). After cold storage, the grafts were put on the recirculating IPRL system, then reperfused for 120 min at 37°C with oxygenated Krebs-Henseleit buffer containing hyaluronic acid (HA). To examine the function of the sinusoidal endothelial cells and hepatocytes, serial measurements of HA, tumor necrosis factor-α (TNFα), thromboxane B₂ (TXB₂), acid phosphatase, and conventional parameters in the perfusate were made. After perfusion, the trypan blue exclusion test was performed to assess the presence of any microscopic sinusoidal lining cell damage. In group 3, the bile output and HA clearance were significantly greater, while glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, TNFα, TXB₂, and acid phosphatase in the perfusate were significantly lower than in group 2. Histologically, less endothelial cell damage and hepatocyte damage than in group 2 was also confirmed. These results therefore suggest that the improvement of hepatic graft viability by PGE₁ administration is mainly due to sinusoidal endothelial cell protection. (Received for publication on Nov. 21, 1996; accepted on Nov. 6, 1998)     

Anesthetic myocardial protection with sevoflurane

OBJECTIVE: To examine the role of sevoflurane in myocardial protection in patients undergoing coronary artery bypass graft (CABG) surgery. DESIGN: Prospective, randomized, controlled, double-blinded study. SETTING: Veterans Administration Medical Center (VAMC), Buffalo, New York. SUBJECTS: Twenty-one patients undergoing CABG were included in the study. Eleven patients were randomized to receive sevoflurane, and 10 patients served as controls. INTERVENTION: Total intravenous anesthesia was provided for both study and control groups by infusion of propofol, fentanyl, and midazolam. Sevoflurane 2% was added to the cardioplegia solution in the experimental group. MEASUREMENTS AND MAIN RESULTS: Neutrophil beta-integrins (CD11b/CD18), tumor necrosis factor alpha (TNF-alpha), and interleukin (IL)-6 were measured as indicators of the inflammatory response to myocardial ischemia-reperfusion injury. Blood samples were obtained from the aorta and coronary sinus before (T1) and immediately after cardiopulmonary bypass (CPB) (T2) and, in addition, from a peripheral artery 6 hours (T3) after CPB. Myocardial function was determined in all patients at each time point. Left ventricular stroke work index (LVSWI) was calculated as an estimation of left ventricular function. Left ventricular regional wall motion abnormality (RWMA) was assessed by transesophageal echocardiography at T1 and T2 time points. TNF-alpha was detectable only in the control group in arterial samples at T3. IL-6 levels (pg/mL) were found to be lower in the sevoflurane group compared with controls at T2 arterial circulation (38.2 +/- 21.1 v 60.6 +/- 19.1, p < 0.05) as well as in the coronary circulation (38.4 +/- 19.9 v 118.2 +/- 23.5, p < 0.01) at T2. CD11b/CD18 increased 79% after CPB in the control group while only increasing 36% in the sevoflurane group (p < 0.05). The post-CPB LVSWI was back to its baseline values in the sevoflurane group, whereas it was still significantly depressed in the control group. Eight of 10 patients in the control group showed a transient new-onset RWMA in either the septal or anteroseptal regions. Only 2 of 11 patients in the sevoflurane group showed transient RWMA of the LV. CONCLUSIONS: Sevoflurane decreases the inflammatory response after CPB, as measured by the release of IL-6, CD11b/CD18, and TNF-alpha. Myocardial function after CPB, as assessed by RWMA and LVSWI, was also improved with sevoflurane. The role of sevoflurane in myocardial protection and the inflammatory response to myocardial reperfusion should be considered.     

Diet-induced protection against lipopolysaccharide includes increased hepatic NO production

The host response to Gram-negative infection includes the elaboration of numerous proinflammatory agents, including tumor necrosis factor alpha (TNFalpha) and nitric oxide (NO). A component of the hepatic response to infection is an elevation in serum lipids, the so-called "lipemia of sepsis," which results from the increased production of triglyceride (TG)-rich lipoproteins by the liver. We have postulated that these lipoproteins are components of a nonadaptive, innate immune response to endotoxin [lipopolysaccharide (LPS)] and have previously demonstrated the capacity of TG-rich lipoproteins to protect against endotoxicity in rodent models of sepsis. Herein we report the capacity of a high-fructose diet to protect against LPS, most likely by inducing high circulating levels of endogenous TG-rich lipoproteins. The protective phenotype included the increased production of NO by hepatic endothelial cells. Rats, made hypertriglyceridemic by fructose feeding, experienced decreased LPS-induced mortality (P < 0.03) and systemic TNFalpha levels (P < 0.05) as compared with normolipidemic (chow-fed) controls. The increased survival was associated with elevated levels of inducible NO synthase (NOS2) mRNA levels and NO production (82 +/- 26 vs 3 +/- 3 nmol nitrite/10(6) cells, P < 0.001) by hepatic endothelial cells. Nonselective NOS inhibitors reversed the protective phenotype in vivo and readily decreased NO production by cultured endothelial cells from hypertriglyceridemic rats in vitro. This study suggests that a high-fructose diet can protect against endotoxicity in part through induction of endogenous TG-rich lipoproteins and hepatic endothelial cell NO production. This is the first report of diet-induced hyperlipoproteinemia and subsequent protection against endotoxemia.     

乙酰半胱氨酸对脑死亡大鼠肝脏的保护作用

目的探讨乙酰半胱氨酸(NAC)对脑死亡大鼠肝脏损伤的保护作用。方法将30只大鼠随机分为空白对照组(C)、脑死亡组(B)、NAC保护组(N)。各组动物均于脑死亡4h后采集血清检测丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)、透明质酸(HA)及肿瘤坏死因子α(TNFα),并切取肝组织行电镜观察。结果脑死亡4h后,B组、C组和N组血清ALT水平(U/L)分别是142.88±4.12、43.38±2.33和101.38±5.37,AST水平(U/L)是283.00±12.74、120.38±4.07和216.54±7.16,HA(μg/L)是168.98±2.59、61.14±1.10和139.31±2.61,TNFα(μg/L)是1.26±0.041、0.62±0.03和0.96±0.07;B组较C组、N组显著升高(P<0.05),N组较C组显著升高但明显低于B组(P<0.05)。电镜观察示B组大鼠肝脏Kupffer细胞明显活化、肝窦内皮细胞与基质部分脱落、肝窦内皮窗口扩大,N组Kupffer细胞活化明显减轻、内皮细胞基本完整。结论脑死亡可致大鼠肝脏损伤,NAC对脑死亡大鼠肝脏损伤具有保护作用。     

挥发性麻醉药对缺血/再灌注肺损伤的保护机制

挥发性麻醉药对肺的作用目前尚有争议,但其抑制炎症反应的效应抗缺血/再灌注(I/R)损伤的保护性效应已在心肌、脑、肝、肾脏中得到证实.现就挥发性麻醉药对肺泡毛细血管的通透性、炎症因子、中性粒细胞的聚集及黏附分子的表达等的影响阐述挥发性麻醉药的肺保护的作用及机制.     

针刺预处理对脑缺血/再灌注损伤的保护作用

针刺预处理的脑保护可能机制如下:减轻脑水肿和微血管损伤,增加脑血流量,影响缺血脑组织在病理形态学及超微结构改变,有利于维持细胞内外离子的稳态,对抗自由基损伤及脂质过氧化反应.并影响细胞因子、神经递质及脑细胞信号转导、凋亡调节基因等;针刺预处理对脑缺血/再灌注的保护效果表现为其穴位、刺激频率和刺激持续时间上的特异性.     

Role of progesterone in melatonin-mediated protection against acute kidney injury

Background

Melatonin is released by pineal gland and maintains circadian rhythm in the body. It has been reported as renoprotective agent because of its antioxidant property. Recently, a cross talk between progesterone and melatonin has been observed in various preclinical studies. The present study investigated the involvement of progesterone receptors in melatonin-mediated protection against ischemia reperfusion induced acute kidney injury (AKI) in rats.

Materials and methods

The rats were subjected to bilateral renal ischemia for 40 min followed by reperfusion for 24 h to induce AKI. The AKI was assessed by measuring creatinine clearance, serum urea, uric acid level, potassium level, fractional excretion of sodium, lactate dehydrogenase activity, and microproteinuria. The oxidative stress in renal tissues was assessed by quantification of myeloperoxidase activity, thiobarbituric acid reactive substances, superoxide anion generation, reduced glutathione level, and catalase activity. The hematoxylin–eosin staining was carried out to observe histopathologic changes in renal tissues. The melatonin (4 and 10 mg/kg, intraperitoneally) and progesterone receptor antagonist mifepristone (5 mg/kg, intraperitoneally) were used in the present study.

Results

The renal ischemia reperfusion induced AKI as indicated by significant change in serum, urinary, and tissue parameters that was ameliorated by prior treatment with melatonin. No significant difference in serum progesterone level was observed between various groups used in the present study. The prior administration of mifepristone abolished melatonin-mediated protection against AKI.

Conclusions

It is concluded that melatonin treatment affords protection against ischemia reperfusion induced AKI. Moreover, progesterone receptors are essentially involved in mediating protective role of melatonin against AKI in rats.     

High-mobility group box 1 inhibition protects against hepatic ischemia-reperfusion injury

Introduction. Hepatic ischemia followed by reperfusion (I/R) occurs in the settings of trauma, transplantation, and elective liver resections. The mechanisms that account for local organ damage are only partially understood. High-mobility group box 1 (HMGB1) has been identified as a late mediator of lethality in sepsis and is released by damaged tissues where it could also act as a mediator of inflammation and organ injury. We hypothesized that HMGB1 would contribute to organ injury following hepatic I/R. Methods. HMGB1 protein expression and hepatocellular secretion were determined in rat hepatocytes subjected to hypoxia (1% O₂) versus normoxic cells. The role of HMGB1 in mediating hepatic I/R injury was examined in C57Bl/6 mice that underwent 90 min of partial I/R injury. These mice were pretreated with neutralizing HMGB1 antibody (600 μg) or control normal saline 1 h prior to ischemia. Results. Basal HMGB1 expression was observed in normoxic hepatocytes and was dramatically up regulated 12-24 h after hypoxia. This corresponded to increased HMGB1 secretion 18-24 h after hypoxia. In mice undergoing partial warm liver I/R injury, HMGB1 protein expression is increased as early as 1 h after reperfusion and then increases in a time-dependent manner up to 24 h. Inhibition of HMGB1 activity with neutralizing antibody significantly decreased liver damage after warm ischemia compared to control animals.

TABLE—ABSTRACT 81.

Group	ALT-1 h	ALT-6 h	ALT-24h
Sham	67 ± 24	57 ± 8	51 ± 2
Control	3101 ± 1167	8140 ± 1656	905 ± 65
Anti-HMGB1	662 ± 120∗	2382 ± 687∗	265 ± 16∗

Note. Data are mean ± SEM, n = 3-4 per group;

∗

indicates P < 0.05 versus control.

Full-size table

     

Anesthetic management of traumatic brain injury

The management of TBI remains an important and frustrating component of the practice of anesthesiology and critical care medicine. The difficulties in management of TBI as well as the poor response rates to medical therapy after TBI are not new. The following passage appeared in the introductory chapter of a text on TBI from 1897: "The manner of treatment is of importance in only a minority of cases, since many subjects of intracranial injury are fated to die whatever measures may be adopted for their relief, and a still greater number are destined to recover though left entirely to the resources of nature. It is probable that in by far the larger proportion of cases in which the issue is determined by treatment it is met in the initial stage, and by insuring restoration from primary shock" [111]. Although secondary insults from factors such as hypotension, hypoxemia, and hyperventilation increase morbidity and mortality, data are not yet available to indicate whether scrupulous prevention and prompt treatment of secondary injuries will reduce morbidity and mortality. In addition, no specific intervention to date has improved overall long-term outcome. With ongoing research, perhaps active interventions will become available. Until that time, thoughtful and careful attention to physiologic management provides the greatest opportunity for a good outcome.     

Brain and spinal cord preconditioning for the protection against ischemic injury

Recent studies have suggested that the brain preconditioning could induce tolerance to ischemia in humans. It has been believed that newly synthesized proteins are required for the acquisition of delayed tolerance in the brain and spinal cord. However, the mechanism other than the synthesis of neuroprotective proteins may also play a pivotal role. Preconditioning may reprogram the response to ischemic injury as seen during hibernation. Preconditioning with hyperbaric oxygen, volatile anesthetics, and xenon seems to be the focus of the attention from the standpoint of the clinical setting. Strong neuroprotection by the preconditioning with isoflurane and xenon is reported in animal experiments and may change the traditional idea of neuroprotection by anesthetics. The discovery that erythropoietin exerts neuroprotective properties has opened new therapeutic avenues. Erythropoietin is induced in the brain by hypoxic preconditioning and by the pharmacological preconditioning. In addition, the intravenous administration of erythropoietin has been shown to be safe and beneficial for acute stroke in humans. Therefore, erythropoietin is now one of the most promising neuroprotective agents. The research in the brain and spinal cord preconditioning will contribute to the elucidation of the mechanism of ischemic injury and to the establishment of new therapies for neuroprotection.     

雷米芬太尼预处理对大鼠局灶性脑缺血-再灌注损伤的保护作用

目的观察雷米芬太尼预处理对大鼠局灶性脑缺血再灌注损伤的保护作用。方法23只雄性大鼠,随机分为两组。雷米芬太尼预处理(R)组(n=13)经股静脉注入雷米芬太尼(0.6μg·kg-1·min-1),每次5min输注,连续3次,中间间隔5min;盐水对照(C)组(n=10)经股静脉注入盐水,每次5min输注,连续3次,中间间隔5min;30min后,所有动物用右侧颈内动脉尼龙线线栓法致大脑中动脉阻闭120min,然后拔出尼龙线恢复再灌注。观察再灌注后24h神经功能障碍改变并评分。再灌注24h时处死动物,取大脑行2,3,5triphenyltetrazolium(TTC)染色以计算脑梗死容积百分比。结果缺血再灌注后动物均表现一定神经功能障碍,再灌注24h内C组神经功能障碍逐渐加重,R组则呈减轻趋势;再灌注24h时神经功能障碍评分(NDS)R组明显低于C组(P<0.05);再灌注24h时脑梗死容积百分比,R组明显小于C组(P<0.01)。结论雷米芬太尼预处理对大鼠局灶性脑缺血再灌注损伤可产生保护作用。     

Glutathione uptake and protection against oxidative injury in isolated kidney cells

Analysis with radiotracer and high performance liquid chromatography techniques showed that glutathione (GSH) is transported intact into cells primarily of proximal tubule origin. Characteristics of GSH uptake were the same as previously reported for basal-lateral membrane vesicles, namely, uptake was Na+-dependent, inhibited by gamma-glutamylglutamate and/or probenecid, and not inhibited by cysteinylglycine or the constituent amino acids. Studies with inhibitors of gamma-glutamyltransferase (acivicin) and gamma-glutamylcysteine synthetase (buthionine sulfoximine) showed that GSH uptake, degradation and resynthesis are independent processes. The GSH uptake rate with 1 mM GSH was approximately three-fold greater than the GSH synthetic rate with 1 mM amino acids. To examine whether uptake of GSH can supplement synthesis to protect against injury, we incubated cells with a toxic concentration of t-butylhydroperoxide with or without GSH or its constituent amino acids. Although amino acids provided significant protection, GSH provided greater protection (cells with t-butylhydroperoxide plus GSH were not significantly different from cells alone). This protection by GSH was eliminated by gamma-glutamylglutamate or probenecid, indicating that GSH uptake was required for the protection seen. Protection was also eliminated when the GSSG reductase/GSH peroxidase system was inhibited by bischloronitrosourea (BCNU), indicating that GSH transport affords protection by maintaining GSH levels in the cell. Thus, intact GSH is transported into isolated proximal tubule cells by a Na+-dependent system, and this transported GSH can be used to supplement endogenous synthesis and GSSG reduction to protect cells against oxidative injury.     

Anesthetic considerations for hepatic resection using veno-venous bypass

Anesthetic experience of 4 cases of hepatic resection using veno-venous bypass was reported. Non-forced bypass (passive shunt) was used in case 1. Hepatic resection was performed while supporting hemodynamic stability during the subsequent anhepatic phase using pump-driven veno-venous bypass (active shunt) in case 2-4. Various problems arose in each case. In the non-forced bypass case, hypotension during the bypass created a problem; whereas, hypothermia was pronounced during bypass in the pump-driven bypass cases. Massive transfusion due to bleeding, hypocalcemia, and unintentional hypothermia after veno-venous bypass precipitated heart failure. Attention should therefore be directed toward, (1) preparation for massive transfusion, (2) measurement and correction of the plasma calcium ion concentration, (3) maintenance of body temperature, and (4) hemodynamic control with a Swan-Ganz catheter and an inferior vena cava catheter. Extracorporeal bypass using a pump-driven veno-venous bypass (Bio-pump) and splanchnic decompression system via the portal system appear to be advantageous.     

从急性肾功能衰竭到急性肾损伤认识的转变谈麻醉管理对肾脏的保护

背景 对患者肾功能的保护是临床诊疗过程中的重要目标,改善全球肾病预后组织(kidney disease improvingglobal outcomes,KDIGO)曾先后多次制定了相关肾病的治疗指南. 目的 概述急性肾损伤(acute kidney injury,AKI)的相关研究及其临床意义. 内容 AKI概念的产生、围术期麻醉管理对肾功能的影响及AKI治疗的争议. 趋向 AKI体现了疾病动态演变的过程,提高了对肾损伤的认识,有利于围手术期肾功能的保护.