硫代乙酰胺诱导大鼠急性肝性脑病模型建立的用药时间研究

目的通过硫代乙酰胺（TAA,300mg·kg^-1·d^-1）不同用药时间诱导A型肝性脑病,比较大鼠的行为学、生物化学以及组织学改变,探讨造模最适时间。方法将大鼠分为A、B、C、D四组,其中A组为正常对照组;B、C、Di组用TAA（300mg·kg^-1·d^-1）分别连续灌胃2d、3d、4d,A组用相等量生理盐水灌胃4d。比较各组大鼠行为学变化、脑功能评分、AHE的诱导率和致死率,并分析各组给药结束24h后血氨、ALT、AST、TBIL的差异。结果C、D组比B组大鼠脑功能评分高,差异有统计学意义（P〈0．0083）;C、D组比B组诱导率高（P〈0．0083）,而D组比B、C组的大鼠致死率高,差异有统计学意义（P〈0．0083）;C、D组血氨及ALT、AST、TBIL肝功能指标比B组高,差异有统计学意义（P〈0．0083）;C、D组TAA用药后肝组织学观察炎症浸润、坏死、纤维化等损害最明显。结论300mg·kg^-1·d^-1的TAA连续灌胃3d,行为学改变显著．致死率较低．血氨较高．肝功能损害明显．为TAA诱导大鼠急性肝性脑病适宜时间。     

Gamma-aminobutyric acid (GABAA) receptor-function in a rat model of hepatic encephalopathy

The functional activity of the gamma-aminobutyric acid (GABA_A) receptor-chloride ionophore complex was studied in rats with hepatic encephalopathy (HE) secondary to thioacetamide-induced fulminant hepatic failure (FHF). Muscimol stimulation and benzodiazepine potentiation of GABA receptor-mediated³⁶Cl^– uptake into cerebral cortical synaptoneurosomes was compared in HE and control rats. [³H]Flumazenil binding assays were conducted to determine whether the levels of endogenous benzodiazepine-like ligands in extracts of cortex were increased with stages of encephalopathy in this animal model of HE. In both control and HE rats maximal uptake of³⁶Cl^– via the GABA_A receptor complex occurred at muscimol concentrations of 30M. Potentiation of muscimol-stimulated³⁶Cl^– uptake into synaptoneurosomes by diazepam (5M) was equivalent in both groups. Aqueous extracts of proteolytically digested homogenates of cerebral cortices prepared from control and HE rats were effective in stimulating³⁶Cl^– uptake into synaptoneurosomes. Alkaline organic extracts of proteolytically digested homogenates of cerebral cortices from HE rats were more effective than corresponding extracts from controls at inhibiting the binding of [³H]flumazenil. Inhibition of [³H] fumazenil binding by organic extracts derived from the cerebral cortices of HE rats did not increase with progression of encephalopathy. The results show that muscimol-stimulated³⁶Cl^– uptake into synaptoneurosomes and, consequently, GABA^A receptor-mediated chloride channel function are not significantly altered in the model of HE studied and are consistent with the hypothesis that HE results in an increased availability of one or more endogenous ligands which can augment GABA receptor-gated chloride conductance.     

Flumazenil does not affect the increase in rat hippocampal extracellular glutamate concentration produced during thioacetamide-induced hepatic encephalopathy

Hepatic encephalopathy (HE) is a neuropsychiatric disorder that often occurs as a consequence of acute or chronic liver failure. Previous reports have suggested that alterations in amino acid neurotransmission, particularly glutamate, may play an important role in the pathogenesis of HE. The objectives of the present study were to test the hypothesis that extracellular glutamate concentration is increased during HE, and to determine if flumazenil, a benzodiazepine antagonist, alters the extracellular concentration of glutamate during HE. The experimental approach involved using microdialysis probes to measure rat hippocampal extracellular glutamate concentration. HE was brought about as a result of thioacetamide-induced liver failure. Thioacetamide produced behavioral and metabolic effects, such as somnolence, hyperventilation and hyperammonemia, consistent with stage three HE. Comparison with saline-treated rats demonstrated that HE was associated with a significant increase (p=0.010) in extracellular hippocampal glutamate concentration. Administration of flumazenil caused a transient increase in arousal level, but did not affect the increase in glutamate concentration (p=0.93). These results corroborate the theory that glutamate neurotransmission is altered during HE and suggest that the flumazenil arousal of HE rats is not mediated by a change in extracellular glutamate concentration.     

Minimal hepatic encephalopathy

Minimal hepatic encephalopathy (MHE) is the mildest form of spectrum of hepatic encephalopathy (HE). Patients with MHE have no recognizable clinical symptoms of HE but have mild cognitive and psychomotor deficits. The prevalence of MHE is high in patients with cirrhosis of liver and varies between 30% and 84%; it is higher in patients with poor liver function. The diagnostic criteria for MHE have not been standardized but rest on careful patient history and physical examination, normal mental status examination, demonstration of abnormalities in cognition and/or neurophysiological function, and exclusion of concomitant neurological disorders. MHE is associated with impaired health-related quality of life, predicts the development of overt HE and is associated with poor survival. Hence, screening all patients with cirrhosis for MHE using psychometric tests, and treatment of those patients diagnosed to have MHE has been recommended. Ammonia plays a key role in the pathogenesis of MHE, which is thought to be similar to that of overt HE. Thus, ammonia-lowering agents such as lactulose and probiotics have been tried. These agents have been shown to improve cognitive and psychometric deficits, and have good safety profile. Future studies will better define the role of other drugs, such as rifaximin, acetyl L-carnitine and L-ornithine L-aspartate.     

肝性脑病临床诊治的进展

肝性脑病（HE）是在各种急慢性及终末期肝病的基础上出现的以代谢紊乱为主要特征的神经、精神、功能失调综合征。目前一致认为,由于氨中毒及感染使星型胶质细胞肿胀及脑水肿,从而导致这些症状的出现。然而,导致脑部形态学改变的细胞学机制尚未明确。我们可以通过多种方法来诊断及评估不同程度的HE。HE的治疗主要是去除诱因,同时根据有效的经验用药来明确诊断。HE的经验用药主要是使用利福昔明及乳果糖以减少肠道内氨的产生与吸收。     

Development of a three‐factor neuropsychological approach for detecting minimal hepatic encephalopathy

Background: Minimal hepatic encephalopathy (HE) has profoundly negative effects on daily functioning ad quality of life. However, standard psychometric procedures have not been widely incorporated into efforts to develop a neuropsychological battery for this condition. Aims: To establish the construct and diagnostic validity of a neuropsychological approach for the recognition of minimal HE in patients with cirrhosis. Methods: A comprehensive battery of neuropsychological tests was administered to cirrhotic patients with at most grade 1 HE, recruited from the liver transplant and advanced liver disease clinics. An inflammatory bowel disease comparison group was similarly evaluated, thus controlling for the secondary effects of chronic illness on cognition. Testing results for the cirrhosis group were subjected to principal component analysis to establish the relevant cognitive constructs and associated measures. Factor analysis was applied to the neuropsychological battery of 20 tests to determine the cognitive factors to be used. Age‐adjusted standardized neuropsychological factor scores were then compared for the two groups. Results: Factor analysis revealed that our battery of 20 tests was measuring three cognitive factors. Based on the pattern of factor loadings, we labeled these important cognitive factors: global cognitive function; psychomotor speed; and learning and memory. Logistic regression revealed that only impaired psychomotor speed distinguished cirrhotics with no more than grade 1 HE from medically ill controls. Conclusions: The cirrhosis group was characterized by a pattern of preserved global cognitive functioning, mild memory impairment, and moderate psychomotor speed impairment. Discussion: This distinctive pattern of focal psychomotor speed deficits is suggestive of subcortical pathway involvement in minimal HE.     

Hepatic stimulator substance activity in animal model of fulminant hepatic failure and encephalopathy

Hepatic stimulator substance (HSS) is a known liver-specific but species-nonspecific growth factor. In the present study we examined the activity of the endogenously produced HSS in an established experimental model of fulminant hepatic failure (FHF) and encephalopathy, induced by repeated injections of thioacetamide (TAA). FHF was induced by three consecutive intraperitoneal injections of TAA (400 mg/kg body weight) in rats, at time intervals of 24 hr. The animals were killed at 0, 6, 12, or 18 hr following the last injection of TAA. The rate of tritiated thymidine incorporation into hepatic DNA, the enzymatic activity of liver thymidine kinase (EC 2.7.1.21), and the assessment of mitotic index in hepatocytes were used to estimate liver regeneration. HSS extract obtained from the livers of TAA-treated rats, sacrificed at the above-mentioned time points was tested for its activity. Increased HSS activity was noted in all TAA-treated animals, presenting a peak at 12 hr following the third TAA dose, suggesting active participation of this growth factor in hepatocyte replication in this animal model of FHF and encephalopathy. It may also be suggested that up-regulation of HSS activity could be used in future as a therapeutic approach in FHF.     

乳果糖治疗肝性脑病和亚临床肝性脑病149例临床观察

目的 进一步评估乳果糖对肝硬化肝性脑病和亚临床肝性脑病的疗效。方法 观察乳果糖治疗前后患者的精神状态、扑翼状震颤、脑电图、静脉血氨浓度和数字连接试验的改善情况。结果 乳果糖对肝性脑病组的脑病表现总有效率达96.5％,治疗前后静脉血氨浓度和数字连接试验的改善均有非常显著性差异(P<0.01);亚临床肝性脑病组治疗前后血氨有非常显著性差异(P<0.01),数字连接试验有显著性差异(P<0.05)。在乳果糖治疗观察期间,无一例亚临床肝性脑病患者发展为肝性脑病。结论 乳果糖适合于肝硬化肝性脑病和亚临床肝性脑病患者长期服用,可作为预防和治疗肝性脑病的常规用药。     

门冬氨酸鸟氨酸治疗显性和轻微型肝性脑病

检索2000年至2010年期间在国内外发表的有关门冬氨酸鸟氨酸治疗显性肝性脑病（HE）和轻微型肝性脑病（MHE）的文献,并进行分析综述。结果显示,门冬氨酸鸟氨酸的治疗机制是直接降低血氨,疗效可靠,无明显不良反应,其对显性HE的疗效已得到公认,对MHE的疗效也在国内外研究中得到初步证实。     

Psychometric hepatic encephalopathy score for diagnosis of minimal hepatic encephalopathy in China

AIM:To construct normal values for the tests of the psychometric hepatic encephalopathy score(PHES)and to evaluate its usefulness in the diagnosis of minimal hepatic encephalopathy(MHE)among Chinese individuals with cirrhosis.METHODS:The five tests of PHES,number connection test-A(NCT-A),number connection test-B,serial dotting test,line tracing test and digit symbol test(DST),were administered to all enrolled subjects in a quiet room with sufficient light.Cirrhotic subjects with overt HE were excluded by the West-Haven criteria and a detailed neurological examination.Based on the nomograms of healthy volunteers,the patients were classified as having MHE when their PHES was less than-4.RESULTS:In total,146 healthy volunteers completed all the PHES tests.Age and education years were confirmed to be predictors of all five tests.In total,53patients with liver cirrhosis completed the PHES.Of the patients with liver cirrhosis,24(45.3%),22(41.5%)and 7(13.2%)had Child-Pugh grades A,B and C,respectively.MHE was diagnosed in 26 patients(49.1%).Compared with compensated cirrhotic patients(Child A),decompensated cirrhotic patients(Child B and C)had a higher proportion of MHE(65.5%vs 29.2%).No differences in age and education years were found between the MHE and non-MHE groups.NCT-A and DST were able to diagnose MHE with a sensitivity of 76.9%and a specificity of 96.3%(AUC=0.866,K=0.735).CONCLUSION:The proportion of MHE is associated with liver function.NCT-A and DST are simple tools that can be used for the diagnosis of MHE in China.     

Advances in cirrhosis: Optimizing the management of hepatic encephalopathy

Hepatic encephalopathy(HE) is a major complication of cirrhosis resulting in significant socioeconomic burden, morbidity, and mortality. HE can be further subdivided into covert HE(CHE) and overt HE(OHE). CHE is a subclinical, less severe manifestation of HE and requires psychometric testing for diagnosis. Due to the time consuming screening process and lack of standardized diagnostic criteria, CHE is frequently underdiagnosed despite its recognized role as a precursor to OHE. Screening for CHE with the availability of the Stroop test has provided a pragmatic method to promptly diagnose CHE. Management of acute OHE involves institution of lactulose, the preferred first-line therapy. In addition, prompt recognition and treatment of precipitating factors is critical as it may result in complete resolution of acute episodes of OHE. Treatment goals include improvement of daily functioning, evaluation for liver transplantation, and prevention of OHE recurrence. For secondary prophylaxis, intolerance to indefinite lactulose therapy may lead to non-adherence and has been identified as a precipitating factor for recurrent OHE. Rifaximin is an effective add-on therapy to lactulose for treatment and prevention of recurrent OHE. Recent studies have demonstrated comparable efficacy of probiotic therapy to lactulose use in both primary prophylaxis and secondary prophylaxis.     

Minimal hepatic encephalopathy

Minimal hepatic encephalopathy (MHE) is the earliest form of hepatic encephalopathy and can affect up to 80% of cirrhotic patients. By definition, it has no obvious clinical manifestation and is characterized by neurocognitive impairment in attention, vigilance and integrative function. Although often not considered to be clinically relevant and, therefore, not diagnosed or treated, MHE has been shown to affect daily functioning, quality of life, driving and overall mortality. The diagnosis of MHE has traditionally been achieved through neuropsychological examination, psychometric tests or the newer critical flicker frequency test. A new smartphone application (EncephalApp Stroop Test) may serve to function as a screening tool for patients requiring further testing. In addition to physician reporting and driving restrictions, medical treatment for MHE includes non-absorbable disaccharides (eg, lactulose), probiotics or rifaximin. Liver transplantation may not result in reversal of the cognitive deficits associated with MHE.     

Evidence for the presence of a benzodiazepine receptor binding substance in cerebrospinal fluid of a rabbit model of hepatic encephalopathy

Based on the reversal of hepatic encephalopathy in animal models with administration of specific benzodiazepine receptor antagonists, it has been postulated that this syndrome may be mediated by an endogenous benzodiazepine-like compound. In this study using a radioreceptor assay, evidence for the existence of this substance has been demonstrated in cerebrospinal fluid but not sera of rabbits with hepatic encephalopathy due to galactosamine induced hepature failure. Cerebrospinal fluid from rabbits with hepatic encephalopathy caused 36.1 ± 5.03% displacement of³H-Ro 15-1788 specific binding to cortical benzodiazepine receptors, compared to 11.7 ± 0.76% in control animals (P < 0.01). The benzodiazepine receptor binding activity has been shown to behave as a competitive inhibitor of radiolabeled benzodiazepine receptor binding. The finding of endogenous benzodiazepine binding activity affords a potential explanation for the amelioration of hepatic encephalopathy in this model with the administration of benzodiazepine receptor antagonists.     

A new hepatic encephalopathy model to monitor the change of neural amino acids and astrocytes with behaviour disorder

Background/Aims: To elucidate the pathogenesis of hepatic encephalopathy (HE), we developed a new HE model with behaviour disorder. Methods: Male Wistar rats were divided into four treatment groups: a HE model: acetaminophen (APAP)+3‐methylcholanthrene (3‐MC) group (APAP+MC group); control group: acetaminophen group; 3‐methylcholanthrene group; and a no‐treatment group. We monitored the changes of neural amino acids in the synaptic cleft and astrocytes in the brain during behaviour disorder. Results: In the APAP+MC group, alanine amino transferase, blood ammonia and glucose increased from 3 h and total bilirubin increased at 6 h. Prothrombin time was prolonged from 3 h in the APAP+MC group. The APAP+MC group exhibited centrilobular necrosis in the liver after 8 h. In the APAP+MC group, rats jumped vertically and this vertical activity increased significantly from 4 to 7 h. During the behaviour disorder, we found that glutamate and aspartate increased in the synaptic cleft from 4 h after treatment with APAP+3‐MC, glutamate increased 23.9‐fold at 7 h and aspartate increased 16.1‐fold at 4 h, whereas glutamine did not change. At that time, we observed morphological changes of the astrocytes by immunostaining for the glial fibrillary acidic protein. Conclusions: Our new HE model demonstrated that increased excitatory neural amino acids and morphological change in astrocytes were involved in the behaviour disorder that occurs with HE.     

Adenosine influences the high-affinity uptake of transmitter glutamate and aspartate under conditions of hepatic encephalopathy

The high-affinity uptake of transmitter glutamate and aspartate in hippocampal slices incubated in sera from patients with hepatic encephalopathy was dramatically reduced in neuropil areas by more than 50 % compared with the control level. Adenosine compensates for these reduction in reuptake capacity in a concentration-dependent fashion reaching normal values at 500 M adenosine. The renormalization of glutamate and aspartate uptake caused by adenosine might reasonably be expected to have potential therapeutic implications for the treatment of hepatic encephalopathy.     

肝性脑病诊断治疗新认识

新近我国出台了《肝性脑病(HE)诊断治疗专家共识》,成为国际上两个指南的重要补充。按照第11届消化病学大会(WCOG)工作小组的标准,我国的HE以C型为主。同时,HBV携带者首次发病出现重症化时实际系因大块或亚大块肝坏死所致急性肝衰竭(ALF),其HE的机制与C型不同,处理也不同。因此,我国的HE患者除C型外,A型也不少见。磁共振波谱学(MRS)、脑部单光子发射断层扫描(SPECT)和正电子发射断层扫描(PET)是近年来发展较快的HE无创性检查手段。脑水肿发生机制的研究新进展有星形胶质细胞肿胀、细胞外谷氨酸盐变化、脑循环障碍等,而相应对策有NAC、镇静剂、脱水及低温疗法等。关于BCAA疗法,经证实BCAA代谢在ALF是降低的,而在CLF则是增高的,提示前者不宜补充BCAA制剂,后者则可补充BCAA制剂。目前用于HE治疗的药物主要有鸟氨酸-门冬氨酸(OA)、不吸收抗生素和不吸收双糖,而L-鸟氨酸-乙酸苯酯(OP)作为清除血氨的一种新的治疗药物,具有重要的潜在应用价值。     

轻微肝性脑病的治疗现状

轻微肝性脑病(MHE)是肝性脑病发病的起始阶段,无明显的临床表现,但是对患者的日常生活安全产生了严重的影响,在现代医学中受到越来越多的重视,治疗方法主要包括去除诱因和药物治疗两个部分。介绍了轻微肝性脑病的相关治疗,并对各种治疗方案的疗效进行了客观评价。认为现治疗方案主要是多种治疗方法的联合应用,但没有试验证明联合应用可提高疗效。     

Quality of life in patients with minimal hepatic encephalopathy

Minimal hepatic encephalopathy (MHE) represents the mildest type of hepatic encephalopathy (HE). This condition alters the performance of psychometric tests by impairing attention, working memory, psychomotor speed, and visuospatial ability, as well as electrophysiological and other functional brain measures. MHE is a frequent complication of liver disease, affecting up to 80% of tested patients, depending of the diagnostic tools used for the diagnosis. MHE is related to falls, to an impairment in fitness to drive and the development of overt HE, MHE severely affects the lives of patients and caregivers by altering their quality of life (QoL) and their socioeconomic status. MHE is detected in clinically asymptomatic patients through appropriate psychometric tests and neurophysiological methods which highlight neuropsychological alterations such as video-spatial orientation deficits, attention disorders, memory, reaction times, electroencephalogram slowing, prolongation of latency evoked cognitive potentials and reduction in the critical flicker frequency. Several treatments have been proposed for MHE treatment such as non-absorbable disaccharides, poorly absorbable antibiotics such rifaximin, probiotics and branched chain amino acids. However, because of the multiple diagnosis methods, the various endpoints of treatment trials and the variety of agents used in trials, to date the treatment of MHE is not routinely recommended apart from on a case-by-case basis. Aim of this review is analyze the burden of MHE on QoL of patients and provide a brief summary of therapeutic approaches.