Albumin synthesis in cirrhotic subjects with ascites studied with carbonate-14C

Serum Neopterin Levels and IDO Activity as Possible Markers for Presence and Progression of Hepatitis B

Chronic Hepatitis B virus (HBV) is still one of the major reasons for liver related mortality and morbidity all around the world. This study aimed to investigate the possible relationship between the immune system activation and presence, as well as progression, of hepatitis B infection by monitoring the tryptophan degradation and serum neopterin levels in patients with HBV. 110 patients with HBV and 23 healthy subjects were included in the study. The patients had significantly higher neopterin levels and increased kynurenine to tryptophan ratios, which were most probably due to enhanced indoleamine 2,3-dioxygenase (IDO) activity compared to healthy control. A strong positive correlation was found between neopterin levels and IDO activity in patient group. Neopterin levels and IDO activity were markedly increased in patients with histological activity index (HAI) ≥4 compared to HAI<4, and a significant correlation was found between neopterin and HAI. Moreover, there was a significant correlation between albumin levels and IDO activity in HBV patients. These findings suggest that tryptophan degradation results from IFN-γ-induced IDO activation, likewise depletion of albumin synthesis in HBV patients may result from diminished tryptophan availability. In conclusion, based on the study results, serum neopterin levels and IDO activity could provide additional immunological information for monitoring liver histological activity and can be used as prognostic markers in HBV disease.

Modification Patterns of Urinary Albumin Correlates With Serum Albumin and Outcome in Severe Alcoholic Hepatitis

BACKGROUND AND AIMS

Albumin modifications and deranged functions are well documented in serum of severe alcoholic hepatitis (SAH). We investigated whether urinary albumin (u-Alb) can serve as surrogate marker of circulatory albumin phenotype, functionality, and could predict outcome in SAH patients.

PATIENTS AND METHODS

Baseline serum and urine samples from 100 SAH, 20 alcoholic cirrhosis, and 20 healthy controls were subjected to u-Alb, ischemia modified albumin (IMA), IMA to albumin ratio (IMAr), advanced oxidation protein products, advanced glycation end-products, albumin-binding capacity determination. In addition, SAH urinary samples were also analyzed at day 4 and day 7 to predict nonresponse to corticosteroid therapy.

RESULTS

Urine and serum levels of IMA, advanced oxidation protein products and advanced glycation end-products were higher (P<0.05) in SAH versus alcoholic cirrhosis and healthy controls. IMAr was low in urine but high in serum of SAH (P<0.05). Albumin-binding capacity was lower (P<0.05) in both urinary and serum albumin of SAH. Urinary and serum albumin parameters showed direct correlation, whereas IMAr showed inverse correlation (cc>0.2, P<0.05). Baseline u-Alb level was significantly higher in SAH, and was correlated directly with corticosteroid treatment outcome and 12-month mortality in SAH. Baseline u-Alb showed an area under the receivers operating curve analysis of 0.7 and a hazard ratio of 1.23 for prediction of 12-month mortality in SAH. Baseline u-Alb level >9.0 mg/dL was associated with reduced 12-month survival in SAH (log rank <0.01).

CONCLUSIONS

u-Alb modifications are reflective of serum albumin modifications. Further baseline u-Alb levels could be exploited to predict steroid response and mortality in SAH patients.

Molecular Ellipticity of Circulating Albumin-Bilirubin Complex Associates With Mortality in Patients With Severe Alcoholic Hepatitis

BACKGROUND & AIMS

Hyperbilirubinemia and hypoalbuminemia are features of hepatic dysfunction that associate with disease severity. This is because hepatic insufficiency causes hypoalbuminemia, which indirectly increases the circulating levels of free bilirubin. Circular dichroism (CD) spectroscopy can be used to quantify the molecular ellipticity (ME) of the albumin-bilirubin complex, and might associate with the severity or outcome of severe alcoholic hepatitis (SAH).

METHODS

We performed a cross-sectional study of 265 patients with SAH admitted in the Department of Hepatology, Institute of Liver and Biliary Sciences in New Delhi, India from January 2014 through January 2016. Blood samples were collected and patients were followed for 12 months or death. The molar ratios of bilirubin: albumin and albumin-bilirubin complexes were determined for a discovery cohort (30 patients who survived the study period and 60 patients who did not survive) and compared with those of 60 patients with alcoholic cirrhosis and 30 healthy individuals (controls). Optical activities of albumin-bilirubin complexes in blood samples were determined by CD spectroscopy and compared among groups. Findings were validated in a separate cohort of 150 patients with SAH from the same institute. We studied the correlation between ME and albumin binding capacity (ABiC).

RESULTS

The molar ratio of bilirubin: albumin was higher in patients with SAH than with alcoholic cirrhosis or controls (P < .05). Patients with SAH had different CD spectra and higher ME than the other groups (P < .01); ME correlated with model for end-stage liver disease score (with and without Na) and discriminant function (r² > .3; P < .01). ME values above a cut off of 1.84 mdeg predicted 3-month mortality in patients with SAH with an area under receiver operating characteristic curve of 0.87 (95% CI, 0.79-0.95), a 77% positive predictive value, and a 90% negative predictive value. The hazard ratio and concordance index of ME values for 3-month mortality in patients with SAH was 10% higher than the hazard ratio and concordance index of model for end-stage liver disease score. In patients with SAH, there was an inverse correlation between ME and ABiC (r² > 0.7; P < .01). We observed a significant reduction in ABiC with increasing levels of bilirubin in vitro prepared albumin-bilirubin complex.

CONCLUSION

In a cross-sectional study of patients with SAH, we associated ME of the albumin-bilirubin complex, measured by CD spectroscopy, with outcomes of patients with SAH. Increased loading of bilirubin on albumin could explain reduced albumin function. Bilirubin removal by albumin dialysis might benefit patients with SAH.

New Insights About Albumin and Liver Disease

Decompensated liver cirrhosis has a dismal prognosis, with an overall survival of 2-4 years, which is worse than for many oncological diseases. Albumin is an important tool in the management of patients with cirrhosis, since it decreases for less than half the risk for post-paracentesis cardiocirculatory dysfunction and mortality associated with spontaneous bacterial infection, as well as, it triplicates the response to terlipressin in patients with hepatorenal syndrome. Recently, research on albumin has been a hot topic, with important new insights such as the characterization of the pleiotropic effects of albumin (which surpass its oncotic properties) and the concept of effective albumin concentration. In fact, patients with liver cirrhosis present posttranslational modifications on albumin that compromises its function. Those modified albumin forms were proved to have prognostic value and its knowledge may change the paradigm of albumin treatment. In this review, we critically summarize the latest evidence on the potential benefits of albumin in patients with end-stage liver disease.

A Systematic Approach to Patients with Jaundice

Jaundice is a clinical manifestation of disorders of underlying bilirubin metabolism, hepatocellular dysfunction, or biliary obstruction. As clinical presentations of yellowing of eyes or skin can be somewhat nonspecific for the underlying etiology of disease, a stepwise approach to evaluation is necessary for accurate diagnosis and effective treatment plan. In this review, we discuss underlying mechanisms of cholestasis and jaundice as well as laboratory and imaging modalities needed to evaluate a patient presenting with hyperbilirubinemia. Jaundice occurs in settings of cholestasis or inability to effectively secrete bile as well as disorders of bilirubin metabolism and hepatocellular dysfunction. Clinical signs of jaundice occur when the serum bilirubin level exceeds 2.5 to 3 mg/dL. In all cases, evaluation begins with liver chemistry tests which include bilirubin (conjugated and unconjugated), alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, and total protein. In patients with hepatobiliary causes of jaundice, the alkaline phosphatase is usually elevated. In these cases, evaluation of hepatic synthetic function is crucial to the formulation of a treatment plant. When serologic evaluation is combined with hepatobiliary imaging, underlying mechanism of disease can often be elucidated. A stepwise approach to evaluation can be cost and time saving as well as a framework to improve patient outcomes. In this review, we will outline a diagnostic approach to jaundice, beginning with pathophysiology of cholestasis followed by hyperbilirubinemia and markers of synthetic dysfunction.

Factors associated with increased incidence of severe toxicities following yttrium-90 resin microspheres in the treatment of hepatic malignancies

AIM: To further define variables associated with increased incidences of severe toxicities following administration of yttrium-90 (⁹⁰Y) microspheres.

METHODS: Fifty-eight patients undergoing 79 treatments were retrospectively assessed for development of clinical and laboratory toxicity incidence following ⁹⁰Y administration. Severe toxicity events were defined using Common Terminology Criteria for Adverse Events version 4.03 and defined as grade ≥ 3. Univariate logistic regression analyses were used to evaluate the effect of different factors on the incidence of severe toxicity events. Multicollinearity was assessed for all factors with P < 0.1 using Pearson correlation matrices. All factors not excluded due to multicollinearity were included in a multivariate logistic regression model for each measurement of severe toxicity.

RESULTS: Severe (grade ≥ 3) toxicities occurred following 21.5% of the 79 treatments included in our analysis. The most common severe laboratory toxicities were severe alkaline phosphatase (17.7%), albumin (12.7%), and total bilirubin (10.1%) toxicities. Decreased pre-treatment albumin (OR = 26.2, P = 0.010) and increased pre-treatment international normalized ratio (INR) (OR = 17.7, P = 0.048) were associated with development of severe hepatic toxicity. Increased pre-treatment aspartate aminotransferase (AST; OR = 7.4, P = 0.025) and decreased pre-treatment hemoglobin (OR = 12.5, P = 0.025) were associated with severe albumin toxicity. Increasing pre-treatment model for end-stage liver disease (MELD) score (OR = 1.8, P = 0.033) was associated with severe total bilirubin toxicity. Colorectal adenocarcinoma histology was associated with severe alkaline phosphatase toxicity (OR = 5.4, P = 0.043).

CONCLUSION: Clinicians should carefully consider pre-treatment albumin, INR, AST, hemoglobin, MELD, and colorectal histology when choosing appropriate candidates for ⁹⁰Y microsphere therapy.

Probable case of drug reaction with eosinophilia and systemic symptom syndrome due to combination therapy with daclatasvir and asunaprevir

A 66-year-old, interferon-ineligible, treatment-naive man who was diagnosed with chronic hepatitis C due to hepatitis C virus genotype 1b began combination therapy with daclatasvir and asunaprevir. On day 14 of treatment, hepatic reserve and renal function deterioration was observed, while his transaminase levels were normal. Both daclatasvir and asunaprevir were discontinued on day 18 of treatment, because the patient complained of dark urine and a rash on his trunk and four limbs. After discontinuing antiviral therapy, the abnormal laboratory finding and clinical manifestations gradually improved, without recurrence. Our case fulfilled the diagnostic criteria of probable drug reaction with eosinophilia and systemic symptom (DRESS) syndrome. Despite the 18-d treatment, sustained virological response 12 was achieved. Based on the clinical course, we concluded that there was a clear cause-and-effect relationship between the treatment and adverse events. To our knowledge, this patient represents the first case of probable DRESS syndrome that includes concomitant deterioration of hepatic reserve and renal function due to combination therapy with daclatasvir and asunaprevir, regardless of normalization of transaminase levels. Our case suggests that we should pay attention not only to the transaminase levels but also to allergic symptoms associated with organ involvement during combination therapy with daclatasvir and asunaprevir.

The presence of primary sclerosing cholangitis in patients with ileal pouch anal- anastomosis is associated with an additional risk for vitamin D deficiency

Objective: Vitamin D deficiency is common in patients with ileal pouch-anal anastomosis (IPAA) for ulcerative colitis (UC). Whether vitamin D levels are further lowered in patients with concomitant IPAA and primary sclerosing cholangitis (PSC) is not known. The aim of this study was to evaluate the presence of PSC as a risk factor for vitamin D deficiency in patients with UC and IPAA.

Methods: In this case control study, 74 patients with concurrent IPAA and PSC were included in the study group, and 79 patients with IPAA, but without PSC, served as controls. Forty-four variables were analyzed. Univariate analysis and multivariate analysis with stepwise logistic regression were performed.

Results: A total 153 eligible patients were included, with 74 (48.4%) in the study group and 79 (51.6%) in the control group. Vitamin D level in the study group was 18.9 ± 1.4 ng/dL compared with 30.3 ± 1.7 ng/d in the control group (P = 0.011). Vitamin D deficiency (≤ 20 ng/dL) was present in 65 (42.5%) patients. PSC occurred in 49 (75.4%) of the 65 patients with vitamin D deficiency. In the multivariate analysis, only the presence of PSC (odds ratio [OR]: 7.56; 95% confidence interval [CI]: 2.39–24.08; P = 0.001) and vitamin D supplementation (OR: 2.58; 95% CI: 1.57–9.19; P = 0.018) remained associated with vitamin D deficiency.

Conclusion: The presence of PSC was found to be an independent risk factor for vitamin D deficiency in UC patients with IPAA. These patients should be routinely screened and closely monitored for vitamin D deficiency.

Effect of hepatic impairment on the pharmacokinetics and pharmacodynamics of a single dose of rivaroxaban, an oral, direct Factor Xa inhibitor

AIM

This study investigated the effects of hepatic impairment on the pharmacokinetics and pharmacodynamics of a single dose of rivaroxaban (10 mg), an oral, direct Factor Xa inhibitor.

METHOD

This single centre, non-randomized, non-blinded study included subjects with mild (n = 8) or moderate hepatic impairment (n = 8), according to the Child-Pugh classification, and gender-matched healthy subjects (n = 16).

RESULTS

Rivaroxaban was well tolerated irrespective of hepatic function. Mild hepatic impairment did not significantly affect the pharmacokinetics or pharmacodynamics of rivaroxaban, compared with healthy subjects. However, in subjects with moderate hepatic impairment, total body clearance was decreased, leading to a significant increase in the area under the plasma concentration-time curve (AUC). The least-squares (LS)-mean values for AUC were 1.15-fold [90% confidence interval (CI) 0.85, 1.57] and 2.27-fold (90% CI 1.68, 3.07) higher in subjects with mild and moderate hepatic impairment, respectively, than in healthy subjects. Consequently, the pharmacodynamic responses were significantly enhanced in subjects with moderate hepatic impairment. For inhibition of Factor Xa, increases in the area under the effect-time curve and the maximum effect were observed, with LS-mean ratios of 2.59 and 1.24, respectively, vs. healthy subjects. Prolongation of prothrombin time was similar in healthy subjects and those with mild hepatic impairment, but was significantly enhanced in those with moderate hepatic impairment.

CONCLUSION

Moderate (but not mild) hepatic impairment reduced total body clearance of rivaroxaban after a single 10 mg dose, leading to increased rivaroxaban exposure and pharmacodynamic effects.

Effects of albumin administration in serum liver enzymes of rats in the presence of extrahepatic biliary obstruction

PURPOSE

To study the influence of albumin on changes of liver function in the extrahepatic biliary obstruction through an experimental model in rats.

METHODS

Sixty rats were divided into four groups: Group C (Control): 6 animals. Group M (Fictitious Operation): 18 rats underwent laparotomy and handling of the bile ducts; Groups O (extrahepatic biliary obstruction) and A (Treated with 2% albumin): 18 animals in each group underwent ligation of the ductus liver; The animals in groups M, O and A were divided into three subgroups of 6 animals each to be killed in the 7, 14 and 21 days postoperative (POD). Blood was drawn for determination of total bilirubin (TB), indirect bilirubin (IB), direct bilirubin (DB), alkaline phosphatase (ALP), aspartate aminotransferase (AST) and alanine aminotransferase (ALT).

RESULTS

On POD 7, BI levels were 4.5 mg / dl in group O and 2.1 mg / dl in group A (p = 0.025). On the 14th POD, the levels of PA were 1185.2 U / l in the group and O 458.3 U / l in group A (p = 0.004). ALT levels were 101.7 U / l in the group O and 75.7 U / l in group A (= 0.037). On POD 21, the levels of ALP were 1069.5 U / l in the group O and 468.3 U / l in group A (p = 0, 004).

CONCLUSION

The administration of albumin reduced the serum levels of bilirubin in the 7th day of supplementation.

Predictive index for long-term survival after retransplantation of the liver in adult recipients: analysis of a 26-year experience in a single center

OBJECTIVE

To develop a prognostic scoring system for risk stratification of patients with hepatic graft failure (GF) undergoing retransplants of the liver (ReLT) and improve patient selection.

SUMMARY OF BACKGROUND DATA

Retransplantation of the liver remains controversial because of inferior outcomes compared with the primary orthotopic liver transplantation (OLT) and raises concerns of inappropriate utilization of a scarce donor organ resource. Data on risk stratification of ReLT patients for long-term survival outcomes are limited.

METHODS

We conducted an analysis from our prospective database of 466 adults' ReLT between February 1984 and September 2010. Mean follow-up was 3 years. Each independent predictor for allograft failure was assigned risk score (RS) points of 1 or 2, proportional to the corresponding parameter estimate under the Cox model: Predictive index category (PIC) 1, RS = 0; PIC II, RS = 1 to 2; PIC III, RS = 3 to 4; and PIC IV, RS = 5 to 12.

RESULTS

Eight risk factors predictive for GF after ReLT included recipient age greater than 55 years, Model for End-Stage Liver Disease score greater than 27, history of prior OLT greater than 1, pre-ReLT requirement for mechanical ventilation, serum albumin less than 2.5 g/dL, donor age greater than 45 years, intraoperative requirement of packed red blood cell transfusion greater than 30 units, and performance of ReLT between 15 and 180 days from the prior OLT. Five-year GF-free survival was significantly higher in PIC I (65%) than in PIC II (53%), PIC III (43%), and PIC IV (20%) groups (P < 0.001).

CONCLUSIONS

This risk-stratification model was highly predictive of long-term outcome after liver retransplantation in adult recipients. This formula provides a practical guide for selection of candidates for retransplantation of the liver that can lead to improved patient outcomes and optimal utilization of a scarce resource.

Differential effects of growth hormone versus insulin-like growth factor-I on the mouse plasma proteome

The GH/IGF-I axis has both pre- and postpubertal metabolic effects. However, the differential effects of GH and/or IGF-I on animal physiology or the plasma proteome are still being unraveled. In this report, we analyzed several physiological effects along with the plasma proteome after treatment of mice with recombinant bovine GH or recombinant human IGF-I. GH and IGF-I showed similar effects in increasing body length, body weight, lean and fluid masses, and organ weights including muscle, kidney, and spleen. However, GH significantly increased serum total cholesterol, whereas IGF-I had no effect on it. Both acute and longer-term effects on the plasma proteome were determined. Proteins found to be significantly changed by recombinant bovine GH and/or recombinant human IGF-I injections were identified by mass spectrometry (MS) and MS/MS. The identities of these proteins were further confirmed by Western blotting analysis. Isoforms of apolipoprotein A4, apolipoprotein E, serum amyloid protein A-1, clusterin, transthyretin, and several albumin fragments were found to be differentially regulated by GH vs. IGF-I in mouse plasma. Thus, we have identified several plasma protein biomarkers that respond specifically and differentially to GH or IGF-I and may represent new physiological targets of these hormones. These findings may lead to better understanding of the independent biological effects of GH vs. IGF-I. In addition, these novel biomarkers may be useful for the development of tests to detect illicit use of GH or IGF-I.

Liver function tests and their interpretation

Liver function tests (LFT) are a helpful screening tool, which are an effective modality to detect hepatic dysfunction. Since the liver performs a variety of functions so no single test is sufficient to provide complete estimate of function of liver. Often clinicians are faced with reports that do not tally with the clinical condition of the patient and they face difficulty in interpreting the LFT. An attempt is being made to study and understand the LFT and simplify their interpretation with algorithms.

Is portal hypertension associated with protein-losing enteropathy?

BACKGROUND AND AIM

Hypoalbuminemia in patients with decompensated cirrhosis has traditionally been assumed to be a result of to impaired liver synthesis; however, protein-losing enteropathy (PLE) may also contribute. The aim of this study was to assess whether hypoalbuminemic cirrhotic patients with portal hypertension had evidence of PLE.

METHODS

Sixteen patients with alcoholic cirrhosis, hypoalbuminemia and portal hypertension underwent whole gut lavage with polyethylene glycol solution. The effluent obtained was analyzed for albumin, immunoglobulin (Ig)G and alpha1-antitrypsin (alpha1-AT). Serum C-reactive protein (CRP) was also measured to assess the systemic inflammatory response.

RESULTS

Twelve of the 16 enrolled patients had a persistently low albumin concentration at the time of lavage. Only one patient (who was subsequently found to have celiac disease) had elevated concentrations of lavage albumin, alpha1-AT and IgG levels. There was a significant correlation between lavage albumin and alpha1-AT (r = 0.671, P = 0.024), and between lavage albumin and IgG (r = 0.614, P = 0.045). There was no correlation between serum albumin and lavage proteins. Six patients had elevated serum CRP levels, but serum albumin or lavage protein concentrations did not correlate with serum CRP.

CONCLUSION

There is no evidence of a significant PLE in patients with alcoholic cirrhosis, hypoalbuminemia and portal hypertension.

Investigation of albumin-synthesizing ability in rat cirrhotic liver-derived hepatocytes using primary hepatocyte culture

BACKGROUND/AIMS

In cirrhosis, despite a decrease in the total number of hepatocytes, a normal serum albumin level is maintained during the compensatory stage of the disease in many cases. Therefore, to elucidate the mechanism in hepatocytes related to the regulation of the serum albumin level, the albumin-synthesizing ability of individual hepatocytes was investigated in cirrhotic rats.

METHODS

Cirrhotic rats were prepared by oral administration of furfural to male Wistar rats for 20 weeks. Albumin-synthesizing abilities of liver and of isolated hepatocyte culture were evaluated by measuring the albumin concentration in blood and culture supernatant. Expressions of albumin mRNA were compared using Northern blotting. Furthermore, transcriptional activity of the albumin gene was measured using the promoter domain of the gene.

RESULTS

The total number of hepatocytes in rat cirrhotic liver was significantly decreased compared to that in normal rat liver. However, there were no significant differences in levels of serum albumin or albumin mRNA expression between cirrhotic and normal liver. In primary hepatocyte culture, albumin mRNA expression, the amount of albumin secretion and the albumin promoter activity were clearly enhanced in cirrhotic hepatocytes compared to normal hepatocytes.

CONCLUSION

Although the total number of hepatocytes was decreased in the rat cirrhosis models used in this study, the serum albumin level was maintained and albumin-synthesizing ability was enhanced at the transcriptional level in the individual hepatocytes. These results suggest that the maintenance of serum albumin levels in compensated cirrhosis may be due to enhanced albumin synthesis by the hepatocytes.

Low levels of plasma proteins: malnutrition or inflammation?

Levels of several plasma proteins, including albumin, transferrin, and transthyretin (prealbumin), have been proposed as markers for protein energy malnutrition. However, many other factors, especially inflammatory disease and drug or hormone therapy, affect levels of these proteins. These factors probably account for the majority of low levels of transthyretin. Levels of albumin and other proteins may be helpful in determining increased risk of morbidity and mortality, but better markers are needed for diagnosis of protein energy malnutrition per se.

Serum albumin: touchstone or totem?

A decrease in serum albumin concentrations is an almost inevitable finding in disease states, and is primarily mediated in the acute phase by alterations in vascular permeability and redistribution. This change is not disease specific but marked changes that persist are generally associated with a poorer prognosis. Critical appraisal of long-standing practices and the availability of alternative colloid solutions have led to a reduction in albumin replacement therapy, and a widespread tolerance of lower albumin concentrations in patients. The factors determining serum albumin concentrations, their measurement and the implications of hypoalbuminaemia are reviewed. The clinical value of serum albumin measurement is discussed.

Long-term oral administration of branched chain amino acids after curative resection of hepatocellular carcinoma: a prospective randomized trial. The San-in Group of Liver Surgery

BACKGROUND

Live cirrhosis is a state of protein calorie malnutrition which may induce various complications. This study aimed to elucidate if long-term nutritional support with branched chain amino acids (BCAAs) is effective after hepatic resection for hepatocellular carcinoma (HCC).

METHODS

Between 2 and 3 weeks after operation, 75 patients were randomized to receive oral BCAAs (Aminoleban EN) 100 g per day for 1 year, and another 75 patients were assigned to a control group. Mean follow-up times were 35.8 months and 36.0 months respectively.

RESULTS

Flapping tremor was less common, body-weight was greater and performance status was better in the BCAA-treated group throughout the 1-year period. BCAA treatment significantly increased red blood cell and serum albumin level in patients with Child grade B and C disease. Substantially similar effects were observed in those with major hepatic resection. Higher Fischer molar ratios were maintained in the treated group. However, there were no differences in cumulative tumour recurrence and survival rates.

CONCLUSION

Long-term oral nutritional support with BCAAs after resection of HCC is beneficial in improving clinical features and laboratory data without increasing the rate of tumour recurrence, particularly in patients with advanced cirrhosis or after major hepatic resection.

Xenobiotic-induced hepatotoxicity: mechanisms of liver injury and methods of monitoring hepatic function

Xenobiotic-induced liver injury is a clinically important etiology of hepatic disease that, if not recognized, can lead to hepatic failure. In this article we discuss the mechanisms of xenobiotic-induced liver injury, various factors that can alter the risk and severity of injury, the clinical and laboratory manifestations of injury, and the methods used to detect the presence of injury and (or) functioning liver mass.

Evaluation of tests used to screen patients with liver disorders

There is no one test of liver function. Routine laboratory tests that are useful in screening for liver disease and following its course include serum AST, ALT, alkaline phosphatase, protein electrophoresis, prothrombin time, and bilirubin levels. The transaminase levels give a day-by-day account of the amount of hepatocellular injury and death that occurs. Alkaline phosphatase levels estimate the amount of impedance of bile flow. The prothrombin time and serum albumin level are excellent gauges of hepatic protein synthetic ability, whereas the bilirubin level is probably the best test of overall liver function. Many tests are now available that permit one to diagnose specific diseases of the liver.

Characterization of mechanisms causing hypoalbuminemia in rats with long-term bile duct ligation

Albumin kinetics and albumin synthesis were studied in rats with chronic bile duct ligation and compared with pair-fed control rats. The plasma albumin concentration was significantly reduced in bile duct ligated rats as compared to control rats, averaging 35 +/- 1 vs 40 +/- 2 g/l after 2 weeks and 28 +/- 3 vs 38 +/- 5 g/l after 4 weeks of bile duct ligation. Two weeks after bile duct ligation, the transcapillary escape rate of albumin was increased by 60% in bile duct ligated rats, whereas the plasma volume was unchanged. Albumin synthesis expressed as a fraction of total liver protein synthesis, as assessed by the 'flooding' dose method using [3H]phenylalanine, was decreased by 46% in bile duct ligated rats. However, absolute albumin synthesis expressed per 100 g body weight was not different from control rats. Four weeks after bile duct ligation, the transcapillary escape rate of albumin was no longer different, whereas the plasma volume was increased by 38% in bile duct ligated rats. At this time point, albumin synthesis as a fraction of total liver protein synthesis was decreased by 60% in bile duct ligated rats, and absolute albumin synthesis expressed per 100 g body weight averaged 80 +/- 8 vs 53 +/- 12 mg/(day x 100 g) in control and bile duct ligated rats (p < 0.05). The hepatic steady-state levels of albumin mRNA determined by Northern blot analysis were decreased in bile duct ligated rats at both 2 and 4 weeks after surgery. The studies suggest that reduced plasma albumin concentrations in bile duct ligated rats are caused by increased capillary permeability and lack of compensatory increase in albumin synthesis 2 weeks, and by increased plasma volume and decreased albumin synthesis 4 weeks after surgery.

Subnormal albumin gene expression is associated with weight loss in immunodeficient/DNA-repair-impaired wasted mice

OBJECTIVE

Mice bearing the autosomal recessive mutation wst express a disease syndrome of immunodeficiency, neurologic dysfunction, increased sensitivity to the killing effects of ionizing radiation, and dramatic weight loss that begins at 21 days of age and progresses until death at 28-32 days of age. Because of the reported association between abnormal liver status and weight loss, we designed experiments to examine expression of a variety of liver-specific genes in wst/wst mice relative to littermates (wst/.) and parental strain (BCF1) controls.

METHOD

Animals were individually weighed from ages 21-28 days to determine relative weight comparisons between wst/wst mice and controls. Dot blot hybridizations were set up to quantitate the accumulation of transcripts specific for alpha-fetoprotein, albumin and other liver-specific gene products.

RESULTS

These results showed a 67% reduction in albumin mRNA expression in livers derived from wst/wst mice relative to both controls. Expression of alpha-fetoprotein, as well as a variety of other liver-specific genes [secretory component (SC), metallothionein (MT-2), cytochrome P1-450 (Cyt P1-450), transferrin receptor (Tf Rec), tumor necrosis factor (TNF), and immune-associated antigen (Ia)], was unaffected.

CONCLUSIONS

These results suggest a relationship between low albumin expression and wasting syndromes in mice. In addition, our data suggest that the wasted mouse may serve as a unique model for subnormal albumin expression.

Disordered hemostasis in extrahepatic portal hypertension

To assess the contribution of naturally occurring portal-systemic shunts to the coagulopathy of patients with liver disease, we studied laboratory parameters of hemostasis in 20 adult patients with extrahepatic portal hypertension, secondary to portal vein thrombosis, that had resulted in variceal bleeding. All extrahepatic portal hypertension patients had normal liver function and histological appearance. None had any evidence of preexisting coagulation disorders, and none had bled or undergone sclerotherapy in the 6 mo before study. Age- and gender-matched groups of 20 healthy individuals and 20 stable patients with cirrhosis and portal hypertension who had a history of variceal bleeding served as controls. Both patient groups had thrombocytopenia consistent with hypersplenism and portal hypertension. Prothrombin international normalized ratio (extrahepatic portal hypertension, 1.3 +/- 0.12; cirrhosis, 1.7 +/- 0.2; control, 1.02 +/- 0.06; p < 0.05) and partial thromboplastin time ratios (extrahepatic portal hypertension, 1.12 +/- 0.1; cirrhosis, 1.26 +/- 0.2; controls, 1.01 +/- 0.03; p < 0.05) were significantly prolonged in both patient groups. Extrahepatic portal hypertension and cirrhotic patient groups had significantly increased levels of serum total fibrin(ogen)-related antigen (extrahepatic portal hypertension, 818 +/- 150 ng/ml; cirrhosis, 454 +/- 52 ng/ml; controls, 124 +/- 7.3 ng/ml; p < 0.05), fibrin monomer (extrahepatic portal hypertension, 168.8 +/- 16.9 ng/ml; cirrhosis, 115.6 +/- 11.1 ng/ml; controls, 19.7 +/- 0.4 ng/ml; p < 0.05) and D-dimer (extrahepatic portal hypertension, 118 +/- 9.6 ng/ml; cirrhosis, 129 +/- 10 ng/ml; controls, 53.2 +/- 1.6 ng/ml; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Meal stimulation of albumin synthesis: a significant contributor to whole body protein synthesis in humans

The present studies were performed to test the hypothesis that the liver, by increasing the synthesis of specific plasma proteins during the absorption of an amino acid meal, may play an important role in the temporary "storage" of ingested essential amino acids and to explore the effects of glucocorticosteroids and recombinant human growth hormone (rhGH) on these processes. The fractional synthetic rates of albumin and fibrinogen were determined using simultaneous infusions of intravenous [1-14C]leucine and intraduodenal [4,5-3H]leucine after 22 h fasting and during absorption of glucose and amino acids in four groups of normal subjects treated for 1 wk with placebo, prednisone (0.8 mg.kg-1.day-1), rhGH (0.1 mg.kg-1.day-1), or combined treatment. When compared with the fasted state and independent of the route of tracer delivery and hormonal treatment, albumin, but not fibrinogen, synthesis increased (P < 0.0001) during absorption of a mixed glucose amino acid meal in all groups. This increase in albumin synthesis accounted for 28% of the increase in whole body protein synthesis associated with feeding and for 24, 22, and 14% in the prednisone, rhGH, and combined treatment groups, respectively. These data suggest that the stimulation of albumin synthesis observed during feeding prevents irreversible oxidative losses of a significant fraction of ingested essential amino acids and may serve as a vehicle to capture excess dietary amino acids and transport them to peripheral tissues to sustain local protein synthesis.

Albumin mRNA expression in human liver diseases and its correlation to serum albumin concentration

The expression of albumin mRNA in human liver samples was investigated in order to understand the molecular mechanism of albumin gene expression in various liver diseases. Albumin mRNA in acute hepatic failure and decompensated liver cirrhosis was reduced significantly compared to normal control liver (P less than 0.05). Serum albumin concentration is closely correlated with albumin mRNA content (r = 0.895, P less than 0.01). These data suggest that albumin concentration is mainly regulated at albumin mRNA level in the liver despite the presence of other regulatory mechanisms and that expression of albumin mRNA level is correlated with disease severity. But in several cases there was a discrepancy between albumin mRNA level and severity of liver disease, so further investigation of the regulatory factors of albumin gene expression should be performed.

Measurement of albumin synthesis in humans: a new approach employing stable isotopes

A new method for measuring albumin synthesis in humans with stable isotopes is presented. This can readily be applied in most clinical conditions, even when albumin losses are occurring or when repeated assessment is required. After rapid intravenous injection of a large dose of [13C]leucine (57 mg/kg body wt, 19.4 atoms%), plasma samples were taken at intervals up to 90 min. The enrichment of free leucine in plasma measured by gas chromatography-mass spectrometry rose to a peak at 10 min and then fell slowly, whereas that in liver biopsies (from surgical patients) ranged from 101.5 to 80.5% of the plasma value between 10 and 90 min after injection. The fractional synthesis rate (FSR) was calculated by dividing the increase in enrichment of leucine in albumin, measured by gas isotope ratio mass spectrometry, by the area under the plasma free leucine enrichment vs. time curve after allowing for the period between synthesis of the protein and its secretion into the plasma. The FSR in healthy postabsorptive males was 7.2 +/- 1.3%/day, and the absolute synthesis rate was 157 +/- 39 mg.kg body wt-1.day-1. These rates are comparable to those obtained by other methods.

Effect of total enteral nutrition on the short-term outcome of severely malnourished cirrhotics. A randomized controlled trial

Thirty-five severely malnourished cirrhotic patients were randomized to receive either enteral-tube feeding as the sole nutritional support (n = 16) or an isocaloric, isonitrogenous, low-sodium standard oral diet (n = 19). Both groups were homogeneous regarding age, sex distribution, etiology of liver cirrhosis, history of previous complications, clinical status, liver and renal function, modified Child's score, and nutritional status at admission. The enteral formula diet was energy dense, containing 40 mmol Na/day, whole protein plus branched-chain amino acids, medium- and long-chain triglycerides, and maltodextrin. It supplied 2115 kcal/day. The amount of vitamins and trace elements was at the upper limit of the recommended dietary allowances. The orally fed patients were encouraged to eat all meals served. Total enteral nutrition was well tolerated without major complications. Serum albumin and Child's score improved in the enterally fed patients but not in controls. Mortality rate while in the hospital was lower in patients on enteral feeding than in controls (12% vs 47%). These results show that total enteral nutrition is safe and effective in improving the short-term clinical outcome in severely malnourished cirrhotics.

The role of albumin in nutritional support

Hypoalbuminemia is considered one of the hallmarks of protein-calorie malnutrition and chronic liver disease. Recently, serum albumin has also been proposed as a critical predictor of the response to nutritional support and tolerance to enteral feeding in critically ill patients. Albumin is essential for maintenance of plasma colloidal osmotic pressure, prevention of edema, and transport of certain drugs and nutrients. Experimental studies have shown that rapid plasma expansion and reduced plasma protein concentration and osmotic pressure induce a net secretion of sodium and water into the small intestinal lumen. However, the effects of chronic hypoalbuminemia per se on intestinal absorption, independent of malnutrition, have not been fully studied. It is documented that both chronic illness and malnutrition may profoundly affect intestinal anatomical structure and function, inducing some degree of malabsorption. In the last few years, some have advocated albumin infusion to improve clinical response to patients with hypoalbuminemia receiving parenteral nutritional support or to reduce intestinal intolerance and diarrhea in patients receiving enteral tube feeding. A review of the literature shows that both clinical and experimental data to support these suggestions are scarce and further investigations are needed. Hypoalbuminemia is one of many parameters of malnutrition, and it is unlikely that correction of a single parameter for a short time would lead to major clinical benefits.

Changes in albumin, alpha-fetoprotein and collagen gene transcription in CCl4-induced hepatic fibrosis

In efforts to understand mechanisms of liver dysfunction in cirrhosis, transcription of specific genes important to liver function has been measured in the rat model of CCl4-induced hepatic fibrosis. The relative transcription rates of albumin, alpha-fetoprotein and pro-alpha 1-collagen genes were studied during development of fibrosis and after fibrosis was established. During the initial phase of CCl4 administration, there was a decrease in albumin transcription associated with increased alpha-fetoprotein transcription, indicative of active liver regeneration. However, later during development of fibrosis, the response pattern of these genes was different, as albumin gene transcription was normal or increased and alpha-fetoprotein gene transcription was no longer increased. Three weeks after completion of CCl4 treatment (fully established cirrhosis), albumin genes responded normally or hypernormally to an acute regenerative stimulus, but the alpha-fetoprotein gene was again not measurably responsive. Pro-alpha 1-collagen gene transcription increased during the entire fibrogenic process and remained elevated after cirrhosis was established. These studies suggest that a switch from albumin to alpha-fetoprotein gene transcription can serve as a marker of liver regenerative capacity, and that this process is altered during and after development of hepatic fibrosis. The fibrogenic process is also associated with elevated transcription of collagen genes.

Serum albumin

The liver manufactures albumin at a massive rate and decreases production in times of environmental, nutritional, toxic and trauma stress. Osmotic pressure is a basic evolutionary regulatory factor, and hormonal control over albumin production has been demonstrated. Where and why new or old albumin is degraded are questions which have not been clarified, although the vascular endothelium may well be the degradative site. Albumin is important as a transport protein, as a measure of evolution and as a model to study secretion following synthesis without the intervening steps of glycosylation. Investigations as to how this protein enters the endoplasmic membrane may well answer some of the questions concerning signal peptide insertion (288). The role of the urea cycle intermediate ornithine and its participation in polyamine synthesis, which has a positive effect on albumin synthesis, is under study. Likewise, the inverse relation between acute-phase protein synthesis and albumin synthesis regulated by interleukin 1 and other cytokines will merit further study. These are a few of the concepts which will be tested in the future.

When is serum albumin worth measuring?

This paper critically examines the usefulness of serum albumin measurement in the light of current laboratory practice and knowledge of the pathophysiology of albumin metabolism. The main conclusions and recommendations are as follows: (i) Albumin measurement forms a limited, but useful part of the investigation of liver disease; a normal serum albumin concentration makes the diagnosis of cirrhosis unlikely, while a low level in viral hepatitis suggests either severe hepatocellular damage or other complications. (ii) Albumin measurement is essential in selecting patients for, and in determining the amount and frequency of, albumin replacement. (iii) Serum albumin concentration provides a useful indication of prognosis in myeloma. (iv) In the long-term management of patients undergoing enteral or parenteral nutrition, serum albumin concentration is one of several parameters which, together, are useful in predicting the outcome of treatment. (v) The serum albumin concentration may provide a clue to the aetiology of unexplained oedema. (vi) Serum albumin measurement is useful in indicating the level of ionised calcium and of unbound unconjugated bilirubin.