Galactose Clearance Research Articles

Association Between MC-2 Peptide and Hepatic Perfusion and Liver Injury Following Resuscitated Hemorrhagic Shock.

Hemorrhagic shock (HS) due to trauma remains a major cause of morbidity and mortality in the United States, despite continuing progression of advanced life support and treatment. Trauma is the third most common cause of death worldwide and is the leading cause of death in the 1- to 44-year-old age group. Hemorrhagic shock often progresses to multiple organ failure despite conventional resuscitation (CR) that restores central hemodynamics. To examine whether MC-2 would bind glycosaminoglycans to decrease proinflammatory cytokines' influence in the liver, minimize organ edema, prevent liver injury, and improve hepatic perfusion. MC-2, a synthetic octapeptide derived from the heparin-binding domain of murine interferon gamma (IFN-γ), binds glycosaminoglycans to modulate serum and interstitial cytokine levels and activity. A controlled laboratory study of 3y male Sprague-Dawley rats that were randomized to 4 groups of 8 each: sham, sham+MC-2 (50 mg/kg), HS/CR, or HS/CR+MC-2 (HS = 40% of baseline mean arterial pressure for 60 minutes; CR = return of shed blood and 2 volumes of saline). The study began in March, 2013. Effective hepatic blood flow (EHBF) by galactose clearance, wet-dry weights, cytokines, histopathology, complete metabolic panel, and complete blood cell count were performed at 4 hours after CR. MC-2 partially reversed the HS/CR-induced hepatic hypoperfusion at 3 and 4 hours postresuscitation compared with HS/CR alone. Effective hepatic blood flow decreased during the HS period from a mean (SD) of 7.4 (0.3) mL/min/100 g and 7.5 (0.5) mL/min/100g at baseline to 3.7 (0.4) mL/min/100g and 5.9 (0.5) mL/min/100g for the HS/CR and HS/CR+MC-2 groups, respectively (P <.05). Effective hepatic blood flow remained constant in the sham groups throughout the experimental protocol. Organ edema was increased in the ileum and liver in the HS/CR vs sham group, and MC-2 decreased edema in the ileum vs the HS/CR group. MC-2 in HS also decreased levels of alanine aminotransferase, zonula occludens-1, and interleukin-1β compared with HS/CR alone. MC-2 was associated with decreased liver injury, enhanced effective hepatic blood flow, decreased cytokines, and prevention of edema formation in the ileum when administered with CR following HS. These data suggest that the MC-2 peptide could be a potential therapeutic approach to target cytokine and chemokine interactions, which might limit multiple organ failure and decrease mortality in hemorrhagic shock.

The Lumped Constant for the Galactose Analog 2-18F-Fluoro-2-Deoxy-d-Galactose Is Increased in Patients with Parenchymal Liver Disease

The galactose analog 2-(18)F-fluoro-2-deoxy-d-galactose ((18)F-FDGal) is a suitable PET tracer for measuring hepatic galactokinase capacity in vivo, which provides estimates of hepatic metabolic function. As a result of a higher affinity of galactokinase toward galactose, the lumped constant (LC) for (18)F-FDGal was 0.13 in healthy subjects. The aim of the present study was to test the hypothesis of a significantly different LC for (18)F-FDGal in patients with parenchymal liver disease. Nine patients with liver cirrhosis were studied in connection with a previous study with determination of hepatic intrinsic clearance of ¹⁸F-FDGal (V*(max/K*(m)). The present study determined the hepatic removal kinetics of galactose, including hepatic intrinsic clearance of galactose (V(max)/K(m)) from measurements of hepatic blood flow and arterial and liver vein blood galactose concentrations at increasing galactose infusions. LC for ¹⁸F-FDGal was calculated as (V*(max)/K*(m))/(V(max)/K(m)). On a second day, a dynamic ¹⁸-FDGal PET study with simultaneous infusion of galactose (mean arterial galactose concentration, 6.1 mmol/L of blood) and blood samples from a radial artery was performed, with determination of hepatic systemic clearance of ¹⁸F-FDGal (K*(+gal) from linear analysis of data (Gjedde-Patlak method). The maximum hepatic removal rate of galactose was estimated from ¹⁸F-FDGal PET data (V(max)(PET)) using the estimated LC. The mean hepatic V(max) of galactose was 1.18 mmol/min, the mean K(m) was 0.91 mmol/L of blood and the mean V(max)/K(m) was 1.18 L of blood/min. When compared with values of healthy subjects, K(m) did not differ (P = 0.77), whereas both V(max) and V(max)/K(m) were significantly lower in patients (both P < 0.01). Mean LC for ¹⁸LF-FDGal was 0.24, which was significantly higher than the mean LC of 0.13 in healthy subjects (P < 0.0001). Mean K*(+gal) determined from the PET study was 0.019 L of blood/min/L of liver tissue, which was not significantly different from that in healthy subjects (P = 0.85). Mean hepatic V(max)(PET) was 0.57 mmol/min/L of liver tissue, which was significantly lower than the value in healthy subjects (1.41 mmol/min/L of liver tissue (P < 0.0001). Disease may change the LC for a pet tracer, and this study demonstrated the importance of using the correct LC.

Long-term and short-term effects of hemodialysis on liver function evaluated using the galactose single-point test.

Aim. The galactose single-point (GSP) test assesses functioning liver mass by measuring the galactose concentration in the blood 1 hour after its administration. The purpose of this study was to investigate the impact of hemodialysis (HD) on short-term and long-term liver function by use of GSP test. Methods. Seventy-four patients on maintenance HD (46 males and 28 females, 60.38 ± 11.86 years) with a mean time on HD of 60.77 ± 48.31 months were studied. The GSP values were compared in two groups: (1) before and after single session HD, and (2) after one year of maintenance HD. Results. Among the 74 HD patient, only the post-HD Cr levels and years on dialysis were significantly correlated with GSP values (r = 0.280, P < 0.05 and r = −0.240, P < 0.05, resp.). 14 of 74 patients were selected for GSP evaluation before and after a single HD session, and the hepatic clearance of galactose was similar (pre-HD 410 ± 254 g/mL, post-HD 439 ± 298 g/mL, P = 0.49). GSP values decreased from 420.20 ± 175.26 g/mL to 383.40 ± 153.97 g/mL after 1 year maintenance HD in other 15 patients (mean difference: 19.00 ± 37.66 g/mL, P < 0.05). Conclusions. Patients on maintenance HD for several years may experience improvement of their liver function. However, a single HD session does not affect liver function significantly as assessed by the GSP test. Since the metabolism of galactose is dependent on liver blood flow and hepatic functional mass, further studies are needed.

Increased hepatic blood flow during enteral immune-enhancing diet gavage requires intact enterohepatic bile cycling

ObjectivesTotal hepatic blood flow (HBF) via the hepatic artery and portal vein is highly dependent on gastrointestinal perfusion. During postprandial hyperemia, intestinal blood flow depends on nutrient composition, gastrointestinal location, and time. Immune-enhancing diets (IEDs) containing n-3 polyunsaturated fatty acids (PUFAs) selectively augment blood flow in the ileum at 60–120 min via a bile-dependent mechanism. My colleagues and I hypothesized that liver blood flow would be similarly affected by IEDs containing n-3 PUFAs. MethodsMean arterial blood pressure, heart rate, and effective HBF (galactose clearance) were measured in anesthetized male Sprague-Dawley rats after gastric gavage of either a control diet (CD, Boost, Novartis) or an IED (Impact, Nestle Nutrition), with or without bile-duct ligation (BDL), and with or without supplemental bile (bovine, dried, unfractionated). Significance was assessed by 2-way ANOVA for repeated measures with the Tukey-Kramer honestly significant difference test. ResultsCompared with baseline levels, a CD increased HBF (peak at 40 min , *P < 0.05) whereas an IED increased HBF in two distinct peaks at 40 min (*P < 0.05) and 120 min (*P < 0.05), but BDL prevented both the early (CD and IED, †P < 0.05) and late peaks (IED, †P < 0.05). Bile supplementation in the CD + BDL or IED + BDL groups restored neither the CD peak nor the early or late IED peaks. ConclusionsHBF during absorptive intestinal hyperemia is modulated by a mechanism that requires an intact enterohepatic circulation. The early peaks at 40 min (CD or IED) were prevented by BDL, even though fat absorption in the proximal gut occurs by bile-independent direct absorption. Bile supplementation with the diet (CD + BDL or IED + BDL) was insufficient to restore HBF hyperemia, which implies that a relationship exists between intestinal and hepatic blood flow that is not solely dependent on bile-mediated intestinal fat absorption and bile recirculation.

Atrial natriuretic peptide reduces hepatic ischemia–reperfusion injury in rabbits

Atrial natriuretic peptide (ANP) has been known to be protective against hepatic ischemia/reperfusion injury. The purpose of this study was to verify the hypothesis that ANP conserves microvascular circulation and reduces ischemia-reperfusion injury in the in vivo rabbit model. With IRB approval, 30 male Japanese white rabbits under pentobarbital anesthesia were studied. These animals were randomly assigned to the following three groups (n = 10 each): control, ANP, and sham group. Animals in the ANP group received continuous infusion of ANP at 0.1 μg/kg/min throughout the study period. Animals in control and ANP groups underwent 90 min of partial hepatic ischemia by clamping the right hepatic artery and portal vein. Descending aortic blood flow (AoF) was monitored with a transit-time ultrasound flowmeter. Hepatic tissue microvascular blood flow (HTBF) at both right (ischemic) and left (nonischemic) lobe was intermittently evaluated with the hydrogen clearance method. After 180 min of reperfusion, hepatic injury was determined with serum AST and ALT. Galactose clearance of reperfused right lobe was also measured as an indicator of hepatic metabolic function. Histopathological change and the number of apoptotic hepatocytes were also evaluated. Systemic hemodynamic data including mean arterial pressure, heart rate, and AoF did not differ among the three groups during the study period. ANP attenuated ischemia-induced right HTBF decrease. ANP also suppressed histopathological degeneration, apoptosis, and decline in galactose clearance after reperfusion. ANP attenuated hepatic microvascular dysfunction and hepatocyte injury after reperfusion without significant hemodynamic change.

Extracorporeal Liver Perfusion System for Artificial Liver Support Across a Membrane

An extracorporeal porcine liver perfusion (ECPLP) system circumvents the limitations of hepatocyte based bio-artificial liver, but its clinical application has been limited so far due to the potential risk of transmission of porcine endogenous retroviruses. The aim of this study was to develop an ECPLP model that can provide artificial hepatic support across a semi-permeable membrane, which has the potential to block porcine viruses due to its pore size. Livers from white landrace pigs were perfused with normothermic oxygenated blood using Medtronic BP560 centrifugal pump (Medtronic, Inc., Minneapolis. MN). This ECPLP system was used to support a "surrogate" patient across the filter Evaclio-EC4A. Function of liver was measured by indocyanine green retention at 15 min (ICGR15). Clearance of galactose, ammonia, and para-aminobenzoic acid infused into the "surrogate" patient circulation was calculated to assess liver support across the membrane. The study was designed as test (n = 15) versus control (n = 5), with control experiments having no liver in the circuit. For the test experiments, we perfused 15 livers with mean hepatic artery pressure of 87 mm Hg and flows of 1.2 L/min. ICGR15 in test experiments was 11%. Ammonia clearance was 945 mg/min/kg, galactose metabolic rate was 111.7 mg/min/Kg, and the hippurate ratio was 91% in the test. In contrast, the control experiments did not show any significant change in the concentration of any of these compounds. Our ECPLP model was able to provide hepatic support in an experimental setting across a hollow fiber filter. Further work on an anhepatic animal is needed prior to application in human trials.

Prominin-1 Mobilisation, Collection and Immunoselection in Cancer Patients for Liver Regeneration.

Abstract 2141Poster Board II-118 Background:CD133+ (Prominin-1 positive) is a 5-transmembrane glycoprotein that identifies immature progenitor stem cells.Immature hematopoietic stem cells retain the possibility to give origin to tissues different from hematopoietic cell lines (transdifferentiation). Material and methods:In this preliminary study we investigated the possibility to mobilize, collect, immunoselect and reinfuse autologous CD133+ immature stem cells in liver cancer patients. This approach was adopted to obtain, in a short time, an adequate volume increase of the disease free liver thus extending the resectability criteria of the liver, with the final goal to prolong survival.We enrolled 4 patients with a large liver cancer and no chance of resection. The mobilization protocol consisted in: G-CSF administration (10 μg/kg/day ) for 3-5 days, peripheral blood stem cell (PBSC) monitoring starting from the 3rd day, leukapheresis (LKF) collection processing 3 blood volumes when CD133+ cells>15 μL. Patients were monitored during mobilization, collection and post collection phase for clinical status, blood pressure and bleeding. Positive CD133+ immunoselection (Miltenyi Clinimacs) was performed on LKF product after overnight storage. Quality controls on positive fraction consisted in viability and purity of CD133+ cells by cytofluorimetric analysis and clonogenic assays. Microbial tests were performed on the negative fraction.After LKF, patients underwent right portal embolization and infusion of CD133+ cells into the opposite portal vein by a percutaneous access. Evaluation of liver regeneration was performed 30 days after stem cell infusion by spiral CT and galactose clearance. Liver resection was carried out if liver regeneration reached 30-40%. Results:Stem cell mobilization, LKF content and immunoselected cells are detailed in tab 1. No relevant side effects were observed. We obtained an efficient stem cell mobilization in all patients enrolled. No bacterial or fungal contamination was observed in cells infused. Results about liver regeneration and patients' follow up are detailed in table 2.Table 1Mobilization, leukapheresis content and characteristics of cells infused.Median pts' weight (range): 79.7 kg (63 -120) Median days for mobilization (range) 4 (3-4) Median WBC count at the time of collection (range) 37.3×106/ml (26-48) Median PBSC at the time of collection (range) CD133+: 21/mL (16-47.7)>CD34+: 41.5/ mL (22-82)Leukapheresis content mean (range) WBC: 113.2×109 (20.4-200.3) CD133+: 172.7×106 (40.1-372.5) CD34+: 265.3×106 (60-592.6)Characteristics of cells infused mean (range) CD133+: 65.7×106 (41-83) CD133+/kg 0.85×106 (0.29-1.35) CD133+ recovery: 38% (26-55) Viability % (7AAD): 98% (96-99) Purity: 94% (91-95)Table 2Liver regeneration after portal vein infusion of CD133+ cells. FLRV(Future Liver Remnant Volume) expressed as volume (cc) and percentage of total liver mass.Case 1Case 2Case 3Case 4Total volume (cc)1745168913082816Basal FLRV (%)441 (25)611/36290/22723/2630 Days post-treatment FLRV (%)920 (48)772/45568/401080/38TumorCholangiocarcinomaHCC multifocal, PV invasionMetastases of rectal cancerMetastases of colon cancerSurgeryResectedProgression of diseaseResectedResectedStatusAlive free from disease (15 months follow-up)Dead (8 months from diagnosis)Alive, residual disease (12 months follow-up )Alive (6 months follow -up), disease progression Conclusions:Our approach to liver regeneration was feasible and safe with no relevant side effects. We observed an efficient stem cell mobilization comparable to healthy donors also in liver cancer patients. The infusion of CD133+ cells allowed a significant hepatic tissue regeneration in all patients. Controlled clinical trials are needed to confirm our preliminary results. Disclosures:No relevant conflicts of interest to declare.

Obesity-induced hepatic hypoperfusion primes for hepatic dysfunction after resuscitated hemorrhagic shock

Obese patients (BMI>35) after blunt trauma are at increased risk compared to non-obese for organ dysfunction, prolonged hospital stay, infection, prolonged mechanical ventilation, and mortality. Obesity and non-alcoholic fatty liver disease (NAFLD) produce a low grade systemic inflammatory response syndrome (SIRS) with compromised hepatic blood flow, which increases with body mass index. We hypothesized that obesity further aggravates liver dysfunction by reduced hepatic perfusion following resuscitated hemorrhagic shock (HEM). Age-matched Zucker rats (Obese, 314-519 g & Lean, 211-280 g) were randomly assigned to 4 groups (n = 10-12/group): (1) Lean-Sham; (2) Lean, HEM, and resuscitation (HEM/RES); (3) Obese-Sham; and (4) Obese-HEM/RES. HEM was 40% of mean arterial pressure (MAP) for 60 min; RES was return of shed blood/5 min and 2 volumes of saline/25 min. Hepatic blood flow (HBF) using galactose clearance, liver enzymes and complete metabolic panel were measured over 4 h after completion of RES. Obese rats had increased MAP, heart rate, and fasting blood glucose and BUN concentrations compared to lean controls, required less blood withdrawal (mL/g) to maintain 40% MAP, and RES did not restore BL MAP. Obese rats had decreased HBF at BL and during HEM/RES, which persisted 4 h post RES. ALT and BUN were increased compared to Lean-HEM/RES at 4 h post-RES. These data suggest that obesity significantly contributes to trauma outcomes through compromised vascular control or through fat-induced sinusoidal compression to impair hepatic blood flow after HEM/RES resulting in a greater hepatic injury. The pro-inflammatory state of NAFLD seen in obesity appears to prime the liver for hepatic ischemia after resuscitated hemorrhagic shock, perhaps intensified by insidious and ongoing hepatic hypoperfusion established prior to the traumatic injury or shock.

Hemorrhage-Induced Hepatic Injury and Hypoperfusion can be Prevented by Direct Peritoneal Resuscitation

BackgroundCrystalloid fluid resuscitation after hemorrhagic shock (HS) that restores/maintains central hemodynamics often culminates in multi-system organ failure and death due to persistent/progressive splanchnic hypoperfusion and end-organ damage. Adjunctive direct peritoneal resuscitation (DPR) using peritoneal dialysis solution reverses HS-induced splanchnic hypoperfusion and improves survival. We examined HS-mediated hepatic perfusion (galactose clearance), tissue injury (histopathology), and dysfunction (liver enzymes). MethodsAnesthetized rats were randomly assigned (n = 8/group): (1) sham (no HS); (2) HS (40% mean arterial pressure for 60 min) plus conventional i.v. fluid resuscitation (CR; shed blood + 2 volumes saline); (3) HS + CR + 30 mL intraperitoneal (IP) DPR; or (4) HS + CR + 30 mL IP saline. Hemodynamics and hepatic blood flow were measured for 2 h after CR completion. In duplicate animals, liver and splanchnic tissues were harvested for histopathology (blinded, graded), hepatocellular function (liver enzymes), and tissue edema (wet–dry ratio). ResultsGroup 2 decreased liver blood flow, caused liver injuries (focal to submassive necrosis, zones 2 and 3) and tissue edema, and elevated liver enzymes (alanine aminotransferase (ALT), 149 ± 28 μg/mL and aspartate aminotransferase (AST), 234 ± 24 μg/mL; p < 0.05) compared to group 1 (73 ± 9 and 119 ± 10 μg/mL, respectively). Minimal/no injuries were observed in group 3; enzymes were normalized (ALT 89 ± 9 μg/mL and AST 150 ± 17 μg/mL), and tissue edema was similar to sham. ConclusionsCR from HS restored and maintained central hemodynamics but did not restore or maintain liver perfusion and was associated with significant hepatocellular injury and dysfunction. DPR added to conventional resuscitation (blood and crystalloid) restored and maintained liver perfusion, prevented hepatocellular injury and edema, and preserved liver function.

Effects of hyperglycemia on quantitative liver functions by the galactose load test in diabetic rats

Blood galactose clearance after an intravenous galactose load has been widely used as a quantitative liver function test. We have developed a novel quantitative rat liver function test, the galactose single point (GSP) method, to assess residual liver function with various injuries by measuring single time point galactose concentration in blood after an intravenous bolus injection of galactose. The goal of this study was to evaluate the influence of nonhepatic factors such as hyperglycemia on GSP and galactose elimination capacity (GEC) in rats. Four groups of animal studies were carried out, as follows: (1) normal control (NC), (2) streptozotocin-induced diabetes (DM), (3) carbon tetrachloride–induced hepatotoxicity (CCl 4), and (4) streptozotocin-induced diabetes with CCl 4-induced hepatotoxicity (DM + CCl 4). The serum glucose levels in the diabetic groups (DM and DM + CCl 4) were significantly increased compared with the NC and CCl 4 groups ( P < .001). A significant increase in hepatic activities of aspartate aminotransferase and alanine aminotransferase was observed in the CCl 4-treated groups (CCl 4 and DM + CCl 4) compared with the NC and DM groups ( P < .001). In comparison with the NC group, the values of GSP and GEC in the diabetic groups (DM and DM + CCl 4) were significantly reduced ( P < .001) and increased ( P < .01), respectively. Galactose single point had highly significant correlations with GEC ( P < .001). These results suggest that galactose metabolism tests—as quantitative parameters of liver function—should be interpreted with caution in the condition of a significant hyperglycemia.

Uncoupling the Systemic Circulation and the Ex Vivo Circuit During Experimental Isolated Liver Perfusion

Performing an ex vivo liver perfusion as a transient liver support requires perfusing the liver with a flow of 1 ml/min per kg of liver, which could reach 25% of the cardiac output when a human liver is used. This high flow could be detrimental in patients with acute liver failure. Therefore, in an ischemic-induced liver failure pig model, we developed a circuit allowing low flows going out of and into the systemic circulation, whereas the flow going through the ex vivo liver is maintained at a high value. This was obtained by uncoupling the ex vivo circuit from the systemic circulation. Ex vivo liver perfusion was performed in a closed circuit with a flow averaging 1 ml/min per kg of ex vivo liver (700 to 800 ml/min, according to the weight of the livers we used). It was linked to the systemic circulation with input and output flows equal to that used during hemodialysis (200 ml/min). Compared with previously reported direct circuits, this perfusion system was well tolerated from a circulatory point of view. After the induction of ischemic liver failure, the ex vivo liver perfusion led to an increase in urea, branched amino acids to aromatic amino acid ratio, and fractional clearance of indocyanine green and galactose and to a decrease in ammonia and lactic acid. This system allowed the ex vivo liver to keep its clearing properties despite a low extracorporeal flow. It represents an extracorporeal circuit that could be used in place of the direct extracorporeal high-flow liver perfusion.

Aminopyrine breath test in cirrhotic patients awaiting liver transplantation: do we really need it ?

Received: 20 April 2004 Accepted: 8 June 2004 Published online: 27 October 2004 Springer-Verlag 2004 Dear Editors: We read with interest the article by Degre and colleagues on the use of the aminopyrine breath test (ABT) to predict mortality among cirrhotic patients waitlisted for liver transplantation (LT) [1]. However, their well-designed study raises questions as to the real impact of such a test in the management of LT waiting lists. Patient stratification—which is often referred to as the sickest first principle—is crucial to any resource allocation, but prediction of post-transplant survival, i.e. utility, is mandatory if an LT programme is to be cost effective. The abysmal gap between organ demand and supply and the everincreasing use of suboptimal donors mandate a policy of effective graft allocation, which is often opposite to the principle of equity. Over the recent years several quantitative tests of liver function (QTLF) have been suggested to assess the hepatic functional reserve in patients with chronic liver disease [2]. These tests include the ABT, the methionine breath test, the galactose clearance capacity, the sorbitol and the indocyanine-green clearance [2, 3]. However, none has proved superior to the traditional Child–Pugh (CP) classification, which is based on clinical and laboratory parameters. Furthermore, QTLF may vary significantly within and across CP classes as a result of enzyme-inducing agents [4] and of causes of disease [5]. To date, it is unclear whether QTLF may provide relevant prognostic information in cirrhotic patients that is superior to that of conventional prognostic parameters or risk scores [2]. The recent introduction of the model for end-stage liver disease (MELD) scoring system for patient prioritisation is based on the assumption that graft allocation should favour the most urgent patients and that the CP-driven allocation system fails to identify seriously ill patients in a timely fashion [6]. However, even though the MELD system is a reliable indicator of patients’ urgency within populations, there are differences in actual calculated risks for a given MELD score between populations [7]. Furthermore, the MELD score has been found to be poorly correlated with post-transplantation outcome, and surrogate prognostic models have been suggested [8]. The assumption that the pretransplantation patient risk is paramount and that every patient has the same right to be offered LT is not the case in most European centres, where a National Health System run programme must comply with economic and ethic issues and face shortage of available resources. Moreover, the impact of marginal donor grafts on post-transplantation outcome is to be taken into account Transpl Int (2004) 17: 651–652 DOI 10.1007/s00147-004-0772-x LETTER TO THE EDITORS

Molecular characterization of the rat Kupffer cell glycoprotein receptor.

The Kupffer cell receptor for glycoproteins has been reported to have a role in clearance of galactose- and fucose-terminated glycoproteins from circulation. Although the gene and a cDNA encoding the receptor have been described, there has been little study of the receptor protein. To address some questions about possible ligands and functions for this receptor, fragments representing portions of the extracellular domain have been expressed and characterized. The extracellular domain consists of a trimer stabilized by an extended coiled-coil of alpha-helices. The receptor displays monosaccharide-binding characteristics similar to the hepatic asialoglycoprotein receptor, but with somewhat less selectivity. The two best monosaccharide ligands are GalNAc and galactose. alpha-Methyl fucoside is a particularly poor ligand. Analysis of Kupffer cell receptor binding to glycoproteins and oligosaccharides released from them reveals highest affinity for desialylated, complex N-linked glycans. The best glycoprotein ligands contain multiple highly branched oligosaccharides. A human ortholog of the rat receptor gene does not encode a full-length protein and is not expressed in liver. These characteristics suggest that the receptor may have functions parallel to those of the hepatocyte asialoglycoprotein receptor in some (but not all) mammalian species.

Hepatic dysfunction following the Fontan procedure.

The Fontan procedure offers a palliation for the hemodynamic derangements associated with congenital heart lesions characterized by a single functional ventricle, but it causes a chronically elevated systemic venous pressure that may result in hepatic congestion. The objective of this study was to characterize hepatic function and its relationship to cardiac function in children who had undergone the Fontan procedure. In a cross-sectional study of 11 children aged 38 months to 216 months (mean, 149 months), the authors evaluated indices of cardiac and hepatic function, including galactose clearance, Doppler hepatic ultrasonography, synthetic function, and markers of liver injury, at 9 months to 176 months (mean, 100 months) after children had undergone the Fontan procedure. The most common biochemical abnormality of hepatic function was a prolongation of the prothrombin time and a low factor V level. There was a trend toward progressive abnormality in prothrombin time with increasing interval since the Fontan procedure. Galactose elimination half-life and galactose elimination capacity were inversely correlated with the time after Fontan (R2= 0.65, P = 0.004). There was no relationship between cardiac functional measurements and liver function. Prothrombin time and galactose elimination half-life are abnormal in children who have undergone the Fontan procedure and may be useful markers of hepatic function in the longitudinal assessment of these patients.

Hepatic Dysfunction Following the Fontan Procedure

ABSTRACTObjectivesThe Fontan procedure offers a palliation for the hemodynamic derangements associated with congenital heart lesions characterized by a single functional ventricle, but it causes a chronically elevated systemic venous pressure that may result in hepatic congestion. The objective of this study was to characterize hepatic function and its relationship to cardiac function in children who had undergone the Fontan procedure.MethodsIn a cross‐sectional study of 11 children aged 38 months to 216 months (mean, 149 months), the authors evaluated indices of cardiac and hepatic function, including galactose clearance, Doppler hepatic ultrasonography, synthetic function, and markers of liver injury, at 9 months to 176 months (mean, 100 months) after children had undergone the Fontan procedure.ResultsThe most common biochemical abnormality of hepatic function was a prolongation of the prothrombin time and a low factor V level. There was a trend toward progressive abnormality in prothrombin time with increasing interval since the Fontan procedure. Galactose elimination half‐life and galactose elimination capacity were inversely correlated with the time after Fontan (R2 = 0.65, P = 0.004). There was no relationship between cardiac functional measurements and liver function.ConclusionsProthrombin time and galactose elimination half‐life are abnormal in children who have undergone the Fontan procedure and may be useful markers of hepatic function in the longitudinal assessment of these patients.

Clinical chemistry of companion avian species: a review.

Birds have evolved alternate physiologic strategies to contend with dehydration, starvation, malnutrition, and reproduction. Basic anatomic and functional differences between birds and mammals impact clinical chemistry values and their evaluation. Interpretation of the results of standard biochemical analyses, including BUN, alanine aminotransferase, aspartate aminotransferase, creatine kinase, gamma glutamyltransferase, bilirubin, ammonia, alkaline phosphatase, cholesterol, bile acids, glucose, albumin, globulins, calcium, phosphorus, prealbumin (transthyretin), fibrinogen, iron, and ferritin, is reviewed and discussed in relation to these physiological differences. The use and interpretation of alternative analytes appropriate for avian species, such as uric acid, biliverdin, glutamate dehydrogenase, and galactose clearance, also are reviewed. Normal avian urine and appropriate use of urinalysis, an integral part of laboratory diagnosis in mammalian species that frequently is omitted from avian diagnostic protocols, is discussed.

Advantages of normothermic perfusion over cold storage in liver preservation.

To minimize the ischemia-reperfusion injury that occurs to the liver with the current method of preservation and transplantation, we have used an extracorporeal circuit to preserve the liver with normothermic, oxygenated, sanguineous perfusion. In this study, we directly compared preservation by the standard method of simple cold storage in University of Wisconsin (UW) solution with preservation by perfusion. Porcine livers were harvested from large white sows weighing between 30 and 50 kg by the standard procedure for human retrieval. The livers were preserved for 24 hr by either cold storage in UW solution (n=5) or by perfusion with oxygenated autologous blood at body temperature (n=5). The extracorporeal circuit used included a centrifugal pump, heat exchanger, and oxygenator. Both groups were then tested on the circuit for a 24 hr reperfusion phase, analyzing synthetic function, metabolic capacity, hemodynamics, markers of hepatocyte and reperfusion injury, and histology. Livers preserved with normothermic perfusion were significantly superior (P=0.05) to cold-stored livers in terms of bile production, factor V production, glucose metabolism, and galactose clearance. Cold-stored livers showed significantly higher levels of hepatocellular enzymes in the perfusate and were found to have significantly more damage by a blinded histological scoring system. Normothermic sanguineous oxygenated perfusion is a superior method of preservation compared with simple cold storage in UW solution. In addition, perfusion allows the possibility to assess viability of the graft before transplantation.

Assessment of Liver Function in Galahs (Eolophus roseicapillus) After Partial Hepatectomy: A Comparison of Plasma Enzyme Concentrations, Serum Bile Acid Levels, and Galactose Clearance Tests

The relative sensitivity of conventional assays of liver function was evaluated in com- parison with galactose clearance, a test of liver function used in humans since the 1960s. Results of galactose clearance tests were compared with plasma enzyme concentrations and serum bile acid levels in clinically normal galahs (Eolophus roseicapillus; n = 8), after celiotomy (n = 4), and after 6% or 18% hepatectomy (n = 8, respectively). Clearance tests and biochemical analyses were performed within 2-4 hours of surgery and at 4 and 7 days after surgery. Celiotomy and 6% and 18% hepatectomy resulted in changes in alkaline phosphatase, aspartate aminotransferase, and al- anine aminotransferase concentrations that were consistent with muscle trauma. Celiotomy and 6% hepatectomy did not significantly alter the results of galactose clearance tests; however, 18% hep- atectomy resulted in significant reduction in galactose clearance and galactose clearance as a func- tion of body surface area (GEC-SA). Galactose single-point concentrations were not significantly elevated at any time during the experiments; however, single-point concentrations were strongly correlated with galactose clearance and GEC-SA values, especially at 80 minutes after galactose injection. Serum bile acid levels were not significantly elevated after celiotomy or partial hepatec- tomy. Measurement of galactose single-point concentrations has the potential to be a simple, sen- sitive method of screening for reduced hepatic function in birds. Galactose clearance and GEC-SA have the potential to be sensitive assays of hepatic functional mass, for use as a noninvasive method of monitoring hepatic function.

Assessment of liver function in chickens using galactose and indocyanine green clearances

Values for galactose and indocyanine green (ICG) clearances, and plasma and serum biochemical markers of liver dysfunction were determined in normal chickens and following coeliotomy, and compared with birds after partial hepatectomy. Clearance tests, and serum and plasma biochemistry were performed 4h, and 4 and 7 days after surgery. Coeliotomy and manipulation of the liver did not delay clearance of either compound. Partial hepatectomy resulted in elevation of galactose single point concentrations but did not significantly alter galactose clearance (GEC) values. Clearance values of ICG were not significantly altered. Biochemical values were not significantly elevated in birds after a partial hepatectomy in comparison with birds after coeliotomy. Galactose single point concentrations have the potential to become a simple, relatively non-invasive method of screening for liver disease, with GEC tests having the potential to quantify the degree of loss of functional hepatic mass.

Identification of Amino Acid Residues That Determine pH Dependence of Ligand Binding to the Asialoglycoprotein Receptor during Endocytosis

The rat hepatic asialoglycoprotein receptor mediates clearance of galactose- and N-acetylgalactosamine-terminated glycoproteins by endocytosis, binding ligands through a C-type, Ca(2+)-dependent carbohydrate-recognition domain (CRD) at extracellular pH and releasing them at lower pH in endosomes. At physiological Ca(2+) concentrations, the midpoint for ligand release from the CRD of the major subunit of the receptor is pH 7.1. In contrast, the midpoint is pH 5.0 for a galactose-binding derivative of the homologous C-type CRD of serum mannose-binding protein, which would thus not efficiently release ligand at an endosomal pH of 5.4. Site-directed mutagenesis of the CRD from the major subunit of the asialoglycoprotein receptor has been used to identify residues that are essential for efficient release of ligand at endosomal pH. The effects of changes to residues His(256), Asp(266), and Arg(270) singly and in combination indicate that these residues reduce the affinity of the CRD for Ca(2+), so that ligands are released at physiological Ca(2+) concentrations. The proximity of these three residues to the ligand-binding site at Ca(2+) site 2 of the domain suggests that they form a pH-sensitive switch for Ca(2+) and ligand binding. Introduction of histidine and aspartic acid residues into the mannose-binding protein CRD at positions equivalent to His(256) and Asp(266) raises the pH for half-maximal binding of ligand to 6.1. The results, as well as sequence comparisons with other C-type CRDs, confirm the importance of these residues in conferring appropriate pH dependence in this family of domains.