Backflux of ammonia from brain to blood in human subjects with and without hepatic encephalopathy

In patients with hepatic encephalopathy (HE) the blood concentration of ammonia is usually highly elevated. Ammonia readily enters brain cells from the blood, and toxic effects of ammonia on brain metabolism and neurotransmission are believed to play a key role in the pathogenesis of HE. It has, however, been a matter of great controversy whether backflux of unmetabolized ammonia (NH(3) + NH(4) (+)) from brain cells to the blood occurs in man. In the present analysis of data from a dynamic PET study of brain (13)N-ammonia metabolism in healthy subjects and cirrhotic patients with and without HE, we provide the first unambiguous evidence for backflux of ammonia from brain cells to the blood in man. The high temporal and spatial resolution of modern PET technology was employed to distinguish between unidirectional blood-brain transport of ammonia and subsequent metabolism of the ammonia in the brain. In all 16 subjects, clearance of the unidirectional transport of (13)N-ammonia from the blood to brain cells (K(1)) was higher than the metabolic clearance of (13)N-ammonia from the blood (K(met)=K(1) k(3)/(k(2)+k(3)). This can only be explained by backflux (k(2)) of ammonia from brain cells to the blood. In conclusion, backflux of ammonia from the brain to the blood does indeed occur in both healthy subjects and cirrhotic patients with and without hepatic encephalopathy.

Prolongation of the QT interval in children with liver failure

BACKGROUND

Alcoholic liver disease has been associated with QT prolongation and sudden cardiac death.

HYPOTHESIS

We evaluated children with hepatic failure to determine whether they have abnormalities of ventricular repolarization.

METHODS

Between October 1990 and January 1996, 38 pediatric patients (mean age 6.5 +/- 7.2 years) underwent evaluation for liver transplantation, including a 12-lead electrocardiogram and an echocardiogram. All patients had normal serum electrolytes, calcium, and magnesium at the time of cardiac evaluation and were not on any medications known to prolong repolarization. Follow-up electrocardiograms were performed on all survivors with QT prolongation following liver transplantation.

RESULTS

Among those evaluated, seven (18%) were noted to have a prolonged QT interval corrected for rate (QTc > 450 ms; range 460-560 ms). All had a structurally normal heart, except one with an atrial and ventricular septal defect. When compared with patients with a normal QT interval, there was no significant difference in serum indices of liver function or indication for liver transplantation. None of the patients developed a ventricular arrhythmia. Two patients with a prolonged QTc died prior to transplant and another died immediately after surgery. All four survivors had normalization of the QTc following liver transplantation.

CONCLUSION

QTc prolongation can be seen in a significant number of children with hepatic failure. While the mechanism is not known, it appears to be reversible following liver transplantation.

The use of the molecular adsorbent recirculating system (MARS) albumin dialysis for the treatment of liver failure: a nursing perpective

Albumin dialysis for the treatment of liver failure was introduced in Canada in 2006. At the London Health Sciences Centre, there have been seven patients treated with this therapy. A few other centres across Canada have started to use this complex therapy. This article includes an overview of liver failure and a description of the role of albumin dialysis in liver failure, the potential adverse effects of this therapy, and the impact of liver dialysis on the nursing care of this patient population.

Temsirolimus in patients with advanced renal cell carcinoma: an overview

Treatment of patients with advanced renal cell carcinoma (RCC) has changed dramatically with the advent of targeted therapeutics. Temsirolimus, an inhibitor of mammalian target of rapamycin (mTOR), has proven beneficial in the treatment of advanced RCC with poor prognosis. The rationale for mTOR inhibitors in treatment of RCC, the pharmacokinetics and toxicities of temsirolimus, landmark clinical trials of temsirolimus in advanced RCC, and the indications for its use in the treatment of RCC are reviewed here. The status of temsirolimus in the rapidly evolving therapeutic landscape of advanced RCC is also discussed.

Haemolytic anaemia as a first sign of Wilson's disease

A 19-year-old female presented with haemolytic anaemia and subsequently developed liver failure. This raised suspicion of Wilson's disease, which was confirmed by Kayser-Fleischer rings, a low ceruloplasmin level, raised 24-hour urinary copper excretion and two mutations in the 'Wilson gene'. She was successfully treated with D-penicillamine and zinc. In young patients with unexplained haemolysis, liver dysfunction or neuro-psychiatric symptoms, Wilson's disease should be considered.

[Autologous bone marrow stem cell transplantation for treatment terminal liver diseases]

OBJECTIVE

To evaluate the effect of autologous bone marrow-derived stem cell (BMSCs) transplantation in the treatment of liver failure and decompensated hepatic cirrhosis.

METHODS

Bone marrow was harvested (65-95 ml) from 24 patients in the transplantation group. The BMSCs were isolated and infused into liver or spleen of patients via hepatic or splenic artery. At different time points after the transplantation, the patients' liver function and prothrombin time (PT) were evaluated, and the survival rate and symptoms of the patients were recorded.

RESULTS

All the serum biochemical indexes remained stable 2 weeks after the transplantation, and at 4 weeks after transplantation, albumin level increased significantly in comparison with the preoperative level (P<0.05). At 12 weeks, the albumin level further increased (P<0.01) along with Pre-ALB (P<0.01), while total bilirubin, tolal bile acid, PT and fibrinogen were all significantly lowered (P<0.05), and globulin, ALT, and AST remained unchanged (P>0.05). One week after the transplantation, improved appetite was observed in 22 cases (91.67%), and 21 cases (87.5%) showed better physical strength; at 2 weeks, hepatic face improved in 15 cases (62.5%), and spider telangiectasia was significantly reduced in one case; at 12 weeks, the survival rate of the patients was 62.5%, and 9 died or gave up treatment due to chronic liver failure complicated by spontaneous bacterial peritonitis, hepatorenal syndrome, or DIC. No complications associated with the transplantation occurred in these patients.

CONCLUSION

BMSC transplantation can significantly improve the liver function of patients with terminal liver disease with good safety and effectiveness.

A case of advanced breast cancer associated with development of liver atrophy with progressive liver failure during treatment

A 44-year-old-female came to our hospital with abdominal distension in April 2005. She had been diagnosed with breast cancer in 1991, which was treated with mastectomy, postoperative radiation therapy,and a five-year course of hormonal therapy. An abdominal computed tomography (CT) scan revealed multiple hypoattenuated lesions in both lobes of her liver, which were diagnosed as metastatic breast cancer by liver biopsy. Weekly chemotherapy with paclitaxel was initiated on May 13. Trastuzumab and tamoxifen were added after two weeks. After six months of treatment, the CT scans showed reductions in the size of her multiple liver metastases along with the development of slight irregularities in the liver surface. Liver dysfunction was improved,and tumor marker BCA225 levels significantly decreased. After ten months of treatment, the CT scan showed nodular irregularity of the hepatic borders with deformation and atrophic changes. After twelve months of treatment,she was readmitted with abdominal distension and lower extremity edema. Increased ascites and appearance of esophageal varices were observed. Laboratory values were compatible with decompensation of liver function,although BCA225 levels still remained low. Despite discontinuation of chemotherapy and hormonal therapy at this time, she died from liver failure less than two weeks later. The atrophic changes and liver failure are suspected to have resulted from the chemotherapy and/or hormonal therapy.

Hereditary systemic angiopathy (HSA) with cerebral calcifications, retinopathy, progressive nephropathy, and hepatopathy

Several hereditary conditions affecting cerebral, retinal and systemic microvessels have recently been described. They include CADASIL, CRV, and HERNS. We here report on a variant form of a hereditary systemic angiopathy (HSA) affecting two generations of a Caucasian family. Clinical symptoms of HSA appear in the mid-forties and are characterized by visual impairment, migraine-like headache, skin rash, epileptic seizures, progressive motor paresis and cognitive decline. Late symptoms include hepatic and renal failure. Retinal capillary microaneurysms and arteriolar tortuosity are associated with marked optic disc atrophy. Radiological hallmarks consist of multiple cerebral calcifications and tumor-like subcortical white matter lesions. Brain, peripheral nerve, muscle, kidney and colon biopsies have revealed a multi organ small vessel involvement with partly altered endothelium, perivascular inflammation and thrombotic microangiopathy. No curative therapeutic options are known for hereditary cerebral vasculopathies. The use of cyclophosphamide, azathioprine and methotrexate was of no benefit in our cases of HSA. Early diagnosis of hereditary systemic angiopathies is important in order to prevent patients from repetitive invasive diagnostic measures and to avoid the use of inappropriate and potentially harmful drugs.

Association between model for end-stage liver disease and spontaneous bacterial peritonitis

OBJECTIVE

To determine whether a greater Model for End-Stage Liver Disease (MELD) score is associated with a greater risk of spontaneous bacterial peritonitis (SBP).

METHODS

Our retrospective case-control study enrolled 271 consecutive patients with cirrhosis and ascites who underwent diagnostic paracentesis upon hospital admission (2002-2005). After excluding immunosuppressed patients, those recently exposed to antibiotics, those with a potential confounding etiology for ascites, and those with a prior history of SBP, 111 were included in the study. SBP was defined as a paracentesis yielding>or=250 neutrophils/mL ascites fluid. Multivariable logistic regression was performed to determine the odds ratio for the development of SBP associated with MELD score and grouped MELD score (<or=15, 16-24, >or=25). Potential confounders assessed included age, diabetes mellitus, gender, race, alcohol use, serum sodium, and etiology of liver disease.

RESULTS

Twenty-nine of 111 hospitalized patients with cirrhosis were found to have SBP. Patient characteristics were similar between groups with and without SBP. The mean MELD score for patients with SBP was 24 and for those without 18 (P=0.0003). The odds ratio for developing SBP by each MELD point was 1.11 (1.05-1.19, P=0.001). Patients with MELD>or=25 had an odds ratio of 9.67 (2.35-39.82, P=0.002) for SBP, compared to subjects with MELD<or=15. None of the potential confounders substantially altered the relationship between MELD and SBP.

CONCLUSIONS

Increasing MELD score is independently associated with a greater risk of SBP. For every point increase in the MELD score, the risk of developing SBP increases by 11%. Our finding has important implications for increasing the suspicion of SBP in patients with elevated MELD scores.

[Hemorheology and microcirculation in some pathologies of internal medicine]

AIM

It is very interesting in physiopathology to evaluate the blood flow in the microvasculature of patients affected by diabetes, arterial hypertension, lipoproteinosis, peripheral occlusive arterial disease (POAD) and liver failure.

METHODS

We studied 4 groups. Group 1: controls formed by 25 healthy subjects (15 males and 10 females aged 36+/-3 years); group 2: diabetes, including 32 patients (group 2A, 20 subjects with diabetes type 1: 12 males and 8 females aged 43+/-4 years and group 2B, 12 subjects with diabetes type 2: 6 males and 6 females aged 45+/-3 years); group 3: liver failure, formed by 6 subjects (3 males and 3 females aged 44+/-5 years); group 4: hypertensives, 50 subjects (group 4A, 28 smokers 12 males and 16 females aged 40+/-4 years and group 4B, 22 non-smokers: 12 males and 10 females aged 38+/-3 years). We evaluated the capillary morphology using computerized videocapillaroscopy, the hemorheology (red blood cell RBC deformability and aggregability) using LORCA (Laser assisted Optical Rotational Red Cell Analyzer) and tissue oxygenation using transcutaneous oxymeter (Periflux 5000 Perimed). Statistical analysis were performed using the Student t-test.

RESULTS

The capillary loops in patients with diabetic microangiopathy had in 50% of the patients studied an image such as ''deer horns'', as ''elephant nose'' in 72% and as ''cork screw'' in 44%. In diabetics we found also a capillary rarefaction in 28% of them. An improvement in perfusion was observed in patients with liver failure one week after liver transplantation from cadaver in 83% of them. Morphological alterations were present in hypertensives (27% in non-smokers, 46% in smokers). The RBC deformability evaluated as elongation index (EI) and RBC aggregability (t1/2 expressed in seconds) were detected using LORCA. Group 1: EI 0.59+/-0.02, t1/2 3+/-1 s; group 2A: EI 0.55+/-0.01; t1/2 2+/-0.5 s p<0.05 vs controls; group 2B: EI 0.56+/-0.01; t1/2 2+/-0.2 s p<0.04 vs controls; group 3: EI 0.56+/-0.02, t1/2 2+/-0.4 s p<0.04; group 4A: EI 0.56+/-0.02, t1/2 2+/-0.6 s p<0.03; group 4B: 0.57+/-0.02, t1/2 2+/-0.6 s p<0.04. We evaluated also the TcpO2 at the dorsum of the right foot expressed in mmHg: group 1, 96+/-11 mmHg; group 2A, 74+/-9 p<0.05 vs controls; group 2B, 76+/-8 mmHg p<0.05; group 3, 69+/-6 mmHg p<0.05; group 4A, 70+/-5 mmHg p<0.05; group 4B, 77+/-9 mmHg p<0.05.

CONCLUSION

This study indicates an interesting and complete methodology in order to evaluate the microcirculation condition in different pathologies inducing microvasculature alterations.

Transplantation of embryonic stem cell-derived endodermal cells into mice with induced lethal liver damage

ESCs are a potential cell source for cell therapy. However, there is no evidence that cell transplantation using ESC-derived hepatocytes is therapeutically effective. The main objective of this study was to assess the therapeutic efficacy of the transplantation of ESC-derived endodermal cells into a liver injury model. The beta-galactosidase-labeled mouse ESCs were differentiated into alpha-fetoprotein (AFP)-producing endodermal cells. AFP-producing cells or ESCs were transplanted into transgenic mice that expressed diphtheria toxin (DT) receptors under the control of an albumin enhancer/promoter. Selective damage was induced in the recipient hepatocytes by the administration of DT. Although the transplanted AFP-producing cells had repopulated only 3.4% of the total liver mass 7 days after cell transplantation, they replaced 32.8% of the liver by day 35. However, these engrafted cells decreased (18.3% at day 40 and 7.9% at day 50) after the cessation of DT administration, and few donor cells were observed by days 60-90. The survival rate of the AFP-producing cell-transplanted group (66.7%) was significantly higher in comparison with that of the sham-operated group (17.6%). No tumors were detected by day 50 in the AFP-producing cell-transplanted group; however, splenic teratomas did form 60 days or more after transplantation. ESC transplantation had no effect on survival rates; furthermore, there was a high frequency of tumors in the ESC-transplanted group 35 days after transplantation. In conclusion, this study demonstrates, for the first time, that ESC-derived endodermal cells improve the survival rates after transplantation into mice with induced hepatocellular injury. Disclosure of potential conflicts of interest is found at the end of this article.

Correlation and comparison of the model for end-stage liver disease, portal pressure, and serum sodium for outcome prediction in patients with liver cirrhosis

BACKGROUND

The model for end-stage liver disease (MELD), hepatic venous pressure gradient (HVPG), and serum sodium (SNa) are important prognostic markers for patients with liver cirrhosis. The correlation among these markers and their predictive accuracy for survival are unclear.

METHODS

A total of 213 cirrhotic patients undergoing hemodynamic measurement were analyzed. The correlations between MELD score, SNa, and hemodynamic parameters were investigated.

RESULTS

There was a significant correlation between MELD and HVPG (r=0.255, P<0.001), between SNa and MELD (r=-0.483, P<0.001), and between HVPG and SNa (r=-0.213, P=0.002). Using mortality as the end-point, the area under receiver operating characteristic curve (AUC) for MELD was 0.789, compared with 0.659 for HVPG (P=0.165) and 0.860 for SNa (P=0.34) at 3 months; the difference between HVPG and SNa was significant (P=0.015). The AUC at 6 months was significantly higher for SNa and MELD compared with that of HVPG. Among 134 patients with low (<14) MELD scores, a high (>16 mm Hg) HVPG, and low SNa (<135 mEq/L) predicted early mortality. In the Cox multivariate model, MELD, HVPG, and Child-Turcotte-Pugh scores were consistently identified as independent poor prognostic predictors when they were treated either as dichotomous or continuous variables in the model.

CONCLUSIONS

MELD score is closely associated with HVPG and SNa in cirrhotic patients. HVPG is not superior to MELD score or SNa for short-term outcome prediction. High HVPG and low SNa may identify high-risk patients with low MELD scores. High MELD, HVPG, and Child-Turcotte-Pugh scores are independent predictors of poor long-term survival.

Chronic liver failure in rats impairs glutamatergic synaptic transmission and long-term potentiation in hippocampus and learning ability

Cognitive function is impaired in patients with liver disease by unknown mechanisms. Long-term potentiation (LTP) in the hippocampus is considered the basis of some forms of learning and memory. The aims of this work were to assess (i) whether chronic liver failure impairs hippocampal LTP; (ii) if this impairment may be due to alterations in glutamatergic neurotransmission, and (iii) if impairment of LTP is associated with reduced learning ability. It is shown that liver failure in Wistar rats induces the following alterations in the hippocampus; (i) alters the phosphorylation of NMDA and AMPA receptors; (ii) reduces the expression of NMDA and AMPA receptors in membranes, (iii) reduces the magnitude of excitatory postsynaptic potentials (EPSPs) induced by activation of NMDA or AMPA receptors, and (iv) impairs NMDA receptor-dependent LTP. Liver failure also impairs learning of the Morris water maze task. Impairment of glutamatergic synaptic transmission and NMDA receptor-mediated responses may be involved in the alterations of cognitive function in patients with liver disease.

Motor activity is modulated via different neuronal circuits in rats with chronic liver failure than in normal rats

The mechanisms by which liver failure alters motor function remain unclear. It has been suggested that liver disease alters the neuronal circuit between basal ganglia and cortex that modulates motor function. Activation of group I metabotropic glutamate receptors in the nucleus accumbens (NAcc) by injecting (S)-3,5-dihydroxyphenylglycine (DHPG) activates this circuit and induces locomotion We analysed by in vivo brain microdialysis the function of the circuits that modulate motor function in rats with liver failure due to portacaval shunt (PCS). We inserted cannulae in the NAcc and microdialysis probes in the NAcc, ventral pallidum (VP), substantia nigra pars reticulata (SNr), medio-dorsal thalamus (MDT), ventro-medial thalamus (VMT) or prefrontal cortex (PFCx). We injected DHPG in the NAcc and analysed extracellular neurotransmitters concentration in these areas. The results indicate that in control rats DHPG induces locomotion by activating the 'normal' neuronal circuit: NAcc --> VP --> MDT --> PFCx. In PCS rats this circuit is not activated. In PCS rats, DHPG injection activates an 'alternative' circuit: NAcc --> SNr --> VMT --> PFCx. This circuit is not activated in control rats. DHPG injection increases dopamine in the NAcc of control but not of PCS rats, and glutamate in PCS but not in control rats. DHPG-induced increase in dopamine would activate the 'normal' neuronal circuit, while an increase in glutamate would activate the 'alternative' circuit. The identification of the mechanisms responsible for altered motor function and coordination in liver disease would allow designing treatments to improve motor function in patients with hepatic encephalopathy.

Impact of Pretransplant MELD Score on Posttransplant Outcome in Orthotopic Liver Transplantation for Patients with Acute-on-Chronic Hepatitis B Liver Failure

This study was performed to evaluate the usefulness of the model for end-stage liver disease (MELD) score in comparison with the Child-Turcotte-Pugh (CTP) score to predict short-term postoperative survival and 3-month morbidity among patients with acute-on-chronic hepatitis B liver failure undergoing orthotopic liver transplantation.

METHODS

We retrospectively analyzed data from all patients undergoing orthotopic liver transplantation in our unit from December 1999 to November 2005, on the admission day MELD and CTP scores were calculated for each patient according to the original formula. We evaluated the accuracy of MELD and CTP to predict postoperative short-term survival and 3-month morbidity using receiver operating characteristic (ROC) analysis and Kaplan-Meier analysis, respectively.

RESULTS

Seven of 42 patients died within 3-months follow-up. The MELD scores for nonsurvivors (32.97 +/- 7.11) were significantly higher than those for survivors (24.90 +/- 4.96; P < .05), CTP scores were significantly higher, too (12.57 +/- 0.98, 11.51 +/- 1.17; P < .05). ROC analysis identified the MELD best cut-off point to be 25.67 to predict postoperative morbidity (area under the curve [AUC] = 0.841; sensitivity = 85.7%; specificity = 60.0%), and the CTP best cut-off point was 11.5 (AUC = 0.747; sensitivity = 85.7%; specificity = 54.3%). MELD score was superior to CTP score to predict postoperative short-term survival and 3-month morbidity among patients with acute-on-chronic hepatitis B liver failure undergoing orthotopic liver transplantation.

CONCLUSION

MELD score was an objective predictive system and more efficient than CTP score to evaluate the risk of 3-month morbidity and short-term prognosis in patients with acute-on-chronic hepatitis B liver failure undergoing orthotopic liver transplantation.

The relationship between a model of end stage liver disease score (MELD score) and the occurrence of spontaneous bacterial peritonitis in liver cirrhotic patients

AIM

To determine relationship between MELD score and the occurrence of SBP, prevalence of SBP, pattern of bacterial culture and antibiotic susceptibility of causative bacteria of liver cirrhotic patients at Sanglah Hospital.

METHODS

Study design was a cross-sectional analytic study. The population in this study consists of liver cirrhotic patients admitted at Sanglah Hospital Denpasar from June 2005 to February 2006.

RESULTS

This result confirmed that the MELD score is a reliable index of disease severity and that higher MELD scores had a significantly more frequent SBP prevalence in patients with a MELD score of 18 or more compared with that in patients with a MELD score of 17 or less (p=0.01; 95% CI = 1.379-15.537). Prevalence of SBP was 30.6%. Thirteen patients (68.4%) had monomicrobial positive culture of Aerob bacteria, consisting of Gram negative bacterias in 10 (77%), with Escherichia coli and Acinettobacter baumanii being the most frequent, and 3 (23%) had Gram positive bacteria. High sensitivity to Cefoperazone, Cefotaxim, Ceftazidime, Cefpirome, Ciprofloxacin, Fosfomicin, Meropenem, Streptomycin, Gentamycin, Trimethoprim/Sulphamethoxazole, were shown.

CONCLUSION

Based on this study we concluded that severe liver cirrhosis with MELD score > or = 18 was associated with an increase risk of SBP, with a prevalence of 30.6%. Common causes of SBP mostly were Escherichia coli and Acinettobacter baumanii, which were sensitive to antibiotic treatment of Cefoperazone, Cefotaxime and Ciprofloxacin.

[Hepatorenal syndrome. What's new in 2007?]

BACKGROUND

Hepatorenal syndrome (HRS) is a serious complication of end-stage liver disease that was associated with a fatal prognosis in the past. A clear definition of HRS and increased understanding of the pathogenesis have led to considerable progress in therapy outcome.

PATHOGENESIS

The major pathogenetic factor is vasodilation of the mesenteric circulation with arterial underfilling and consecutive renal vasoconstriction.

THERAPY AND CONCLUSION

Restoration of an effective arterial blood volume can be achieved by the combination of vasopressor therapy (terlipressin, norepinephrine), in combination with volume expansion (albumin) with a success rate of up to 75%. Restoration of the effective arterial blood volume may also be achieved by implantation of a transjugular intrahepatic portosystemic stent (TIPS). This has also been successful in up to 50% of patients in selected cohorts. Finally, extracorporeal liver support systems based on exchange or detoxification of albumin have been successfully employed in a number of patients. Liver transplantation remains the only principal therapy of HRS as this is the single measure with a curative intent. All other forms of therapy are palliative but may serve as a bridge to liver transplantation.

Artificial and bioartificial liver support: A review of perfusion treatment for hepatic failure patients

Liver transplantation and blood purification therapy, including plasmapheresis, hemodiafiltration, and bioartificial liver support, are the available treatments for patients with severe hepatic failure. Bioartificial liver support, in which living liver tissue is used to support hepatic function, has been anticipated as an effective treatment for hepatic failure. The two mainstream systems developed for bioartificial liver support are extracorporeal whole liver perfusion (ECLP) and bioreactor systems. Comparing various types of bioartificial liver in view of function, safety, and operability, we concluded that the best efficacy can be provided by the ECLP system. Moreover, in our subsequent experiments comparing ECLP and apheresis therapy, ECLP offers more ammonia metabolism than HD and HF. In addition, ECLP can compensate amino acid imbalance and can secret bile. A controversial point with ECLP is the procedure is labor intensive, resulting in high costs. However, ECLP has the potential to reduce elevated serum ammonia levels of hepatic coma patients in a short duration. When these problems are solved, bioartificial liver support, especially ECLP, can be adopted as an option in ordinary clinical therapy to treat patients with hepatic failure.

Nuclear magnetic resonance studies of energy metabolism and glutamine shunt in hepatic encephalopathy and hyperammonemia

Hepatic encephalopathy (HE) in both acute and chronic liver failure is more likely a reversible functional disease rather than an irreversible pathological lesion of brain cells. Metabolic alterations underlie many of the mechanisms leading to HE. This paper summarizes in vivo and ex vivo (1)H-, (13)C-, and (15)N-nuclear magnetic resonance (NMR) spectroscopy data on patients and experimental models of HE. In vivo NMR spectroscopy provides a unique opportunity to study metabolic changes noninvasively in the brain in vivo, and to quantify various metabolites in localized brain areas, and ex vivo NMR permits the high-resolution measurement of metabolites and the identification of different metabolic pathways. In vivo and ex vivo (1)H-NMR investigations consistently reveal severalfold increases in brain glutamine and concomitant decreases in myo-inositol, an important osmolyte in astrocytes. An osmotic disturbance in these cells has long been suggested to be responsible for astrocyte swelling and brain edema. However, ex vivo (13)C-NMR studies have challenged the convention that glutamine accumulation is the major cause of brain edema in acute HE. They rather indicate a limited anaplerotic flux and capacity of astrocytes to detoxify ammonia by glutamine synthesis and emphasize distortions of energy and neurotransmitter metabolism. However, recent (15)N-NMR investigations have demonstrated that glutamine fluxes between neurons and astrocytes are affected by ammonia. Further NMR studies may provide novel insights into the relationship between brain edema and/or astrocyte pathology and changes in inter- and intracellular glutamine homeostasis, which may secondarily alter brain energy metabolism.

Conduction and excitability properties of peripheral nerves in end-stage liver disease

The pathophysiology of hepatic neuropathy is poorly understood, but membrane depolarization due to a toxic inhibition of oxidative metabolism has been proposed. We investigated the relationship between nerve excitability properties, nerve dysfunction, and liver function in 11 pretransplant patients, the majority of whom were oligo- or asymptomatic for peripheral neuropathy. Abnormalities were detected on clinical examination (6), large-fiber nerve conduction (4), and thermal quantitative sensory testing (10). Small-fiber involvement was characterized by elevation of warm more than cold detection thresholds. Autonomic dysfunction was less frequent (4). Nerve excitability parameters in both upper and lower limbs provided evidence of membrane depolarization compared with controls, even in those patients without a history of alcohol abuse. No clear correlation was found between neurophysiological indices and scores of hepatic reserve or various blood parameters including ammonia level. Although chronic membrane depolarization may be involved, the degree of depolarization in large fibers was small, and its role in the pathophysiology of neuropathy uncertain.

Influence of chronic hepatic failure on disposition kinetics of valproate excretion through a phase II reaction in rats treated with carbon tetrachloride

The influence of chronic hepatic failure on the disposition kinetics of valproate (VPA) excretion via a phase II reaction was examined in rats treated with carbon tetrachloride (1.0 mg/kg, s.c., 3 times a week) for 2 or 3 months. There was no significant difference in the plasma concentration-time courses of VPA among the control and two treated groups up to 120 min after i.v. administration of VPA (75 mg/kg), but subsequently the plasma concentrations of the treated groups declined significantly below the control levels. Expression of Mrp2 mRNA in the liver of the treated groups was significantly lower than in the control group; conversely that in the kidney was significantly higher. The enzyme activity of UGTs in the liver of the treated groups decreased significantly, but UGT1A8 mRNA expression in the duodenum was increased about 3-fold. Cumulative excretion of VPA glucuronide (VPA-G) in bile of the treated groups was reduced significantly, while that in urine was markedly increased. In conclusion, the area under the VPA plasma concentration-time curve was decreased significantly in rats with chronic hepatic failure owing to increased excretion of VPA-G via the kidney as a result of induction of Mrp2, and inhibition of enterohepatic circulation of VPA-G.

Predicting abnormal coagulation in ischemic stroke: reducing delay in rt-PA use

Normal prothrombin time (PT) and partial thromboplastin time (PTT) are recommended for administration of recombinant tissue-plasminogen activator (rt-PA) in stroke, but waiting for results can delay use. We examined the charts of 365 stroke patients to assess predetermined risk factors associated with elevated PT/PTT. Elevated PT/PTT can be predicted in patients taking warfarin or heparin/heparinoid or on hemodialysis, according to emergency department triage, with 100% sensitivity and 94.7% specificity. These results could be applied to rt-PA candidates and reduce potential delays.

Bullous pemphigoid after liver transplantation for liver failure

Coomb's positive autoimmune hemolytic anemia with giant cell hepatitis (GCH) is a rare cause of liver failure and is usually associated with poor prognosis. A child with liver kidney microsomal (LKM) antibody positivity underwent successful liver transplantation for liver failure secondary to GCH with Coomb's positive hemolytic anemia. Autoimmune neutropenia developed ten months after transplant. Four months later, pemphigoid skin lesions developed. The diagnosis of bullous pemphigoid (BP) was made on the basis of skin biopsy, direct and indirect immunofluorescence test results. Treatment was with immunosuppressants - prednisone and azathioprine/rapamycin, with addition of dapsone when lesions persisted. This child is unique in that his liver function and hemolytic anemia appeared to normalize after liver transplant, but neutropenia and BP both thought to be autoimmune in etiology, developed more than a year post-transplant.

Aerobic capacity, muscle strength and health-related quality of life before and after orthotopic liver transplantation: preliminary data of an Austrian transplantation centre

OBJECTIVE

Patients before orthotopic liver transplantation usually show a reduced physical performance status, which impacts on their daily life and social participation. This pilot study aimed to evaluate endurance capacity, muscle strength, and quality of life before and after orthotopic liver transplantation in patients in an Austrian transplantation centre.

SUBJECTS

Fifteen patients (male/female = 10:5) were included in the pilot study.

METHODS

Exercise testing, strength testing of knee extensor muscles and of handgrip, and quality of life (SF-36 health survey) were assessed before and after orthotopic liver transplantation (after 1-2 months).

RESULTS

The oxygen uptake at the anaerobic threshold (VO2AT) and isokinetic strength testing of quadriceps femoris muscle did not change significantly from baseline, before transplantation to follow-up after orthotopic liver transplantation. Before orthotopic liver transplantation, quality of life was hampered concerning functional status, emotional role, vitality, and general health perception. Significant improvements of social functioning (p=0.032), vitality (p=0.006), mental health (p=0.004) and general health perception (p=0.002) could be found for this study population after orthotopic liver transplantation.

CONCLUSION

The results of this pilot study including a population of an Austrian transplantation centre indicate deficits of physical performance as well as reduced quality of life in patients before and after orthotopic liver transplantation.