Predicting the decrease of conjugated bilirubin with extracorporeal albumin dialysis MARS using the predialysis molar ratio of conjugated bilirubin to albumin

Selective bilirubin sensor fabrication based on doped IAO nanorods for environmental remediation

In this approach, low-dimensional facile IAO nanorods were prepared by using the hydrothermal technique, which is efficiently applied to develop a non-enzymatic sensor coated with GCE probe by electrochemical reduction method.

Depurative capacity of molecular adsorbent recycling system (MARS): A focus on bilirubin removal

The molecular adsorbent recycling system (MARS) is now widely used in the treatment of patients with hepatic failure (HF). A great deal of interest has been directed toward its effect on clinical outcome, whereas its depurative capacity also needs attention. Bilirubin, a tightly albumin-bound toxin accumulating in patients with HF, is regarded as a surrogate to evaluate the depurative capacity of albumin-bound toxins by blood purification modalities. The removal of bilirubin by MARS is difficult to predict, because both the clearance of bilirubin and the reduction ratio of bilirubin after a single session differ between patients and sessions. A reduction of depurative capacity over the course of a treatment is observed. Furthermore, the later sessions are likely less efficient than previous ones. It cannot be taken for granted that the reduction of depurative capacity is due to the saturation and reduced efficiency of the adsorbent columns used in MARS. The answer lies in the property of bilirubin/albumin binding. The removal of bilirubin by MARS is a diffusion process, dependent on the free bilirubin concentration. Bilirubin binds to albumin in 3 ways with different affinity. High-affinity binding bilirubin is difficult to dissociate from albumin and is accompanied by a smaller free fraction, which means it is also difficult for MARS to remove. The factors affecting the free fraction of bilirubin will impact on bilirubin removal by MARS. Among them, the molar ratio of bilirubin to albumin is the most important one. Other factors include the interaction of other agents with bilirubin/albumin binding, the albumin concentration, plasma ion strength, and pH.

Significant Decrease in Dialysate Albumin Concentration during Molecular Adsorbent Recirculating System (M.A.R.S.) Therapy

Aim

The molecular adsorbent recirculating system (M.A.R.S.) is widely used as liver support therapy in patients with hepatic dysfunction. The goal of this study was to measure changes in dialysate albumin and bilirubin concentrations during clinical MARS treatments.

Methods

Eight patients with acute liver dysfunction and hyperbilirubinemia were enrolled in this study. Five of them received a total of 10 treatments with MARS, in which 600 mL of 20% human albumin was used as dialysate, continuously regenerated by two adsorbent columns in the circuit. Three patients received 4 treatments of a modified MARS, in which the two adsorbent columns were bypassed in the first course for 4 h, and then connected to the circuit in the second course for another 4 h. The total, conjugated and unconjugated bilirubin (TB, CB, UCB) and albumin concentrations in serum and albumin dialysate were dynamically measured, and the adsorbent column inlet pressures were recorded during each session. In one session, dialysate albumin levels were measured during the priming process, at the time points prior to the priming process, immediately after priming, and at the end of the treatment.

Results

During MARS therapies, the reduction ratio of serum TB, CB and UCB was 26.6±9.0%, 29.5±9.6% and 14.8±12.3%, respectively. The molar ratio of TB/albumin in serum was approximately 20-fold higher than dialysate at all time points. A significant albumin concentration decrease from baseline in the dialysate was found (mean±SD, 34.6±16.6%). For the first four hours of modified treatments, in which only albumin dialysis without albumin regeneration by adsorbent columns was performed, the dialysate albumin decrease was substantially smaller (mean, 8.3±1.5%). After switching to standard MARS, there was a further decrease in the dialysate albumin concentration of 35.1±14.5%. In one session, dialysate albumin concentrations were measured during the priming process, and levels decreased from 196.9 g/L to 144.4 g/L. Adsorber inlet pressure increased from 40±10mmHg at the start of priming to 150±50mmHg at the end of priming, and further increased to 340±100mmHg at the end of treatment.

Conclusion

There is a significant reduction in dialysate albumin concentration during MARS therapy. Binding of albumin to the adsorbent columns used for albumin regeneration is largely responsible for this decrease.

Electrochemical biosensor with graphene oxide nanoparticles and polypyrrole interface for the detection of bilirubin

A bilirubin biosensor was fabricated by immobilization of bilirubin oxidase (BOx) on a graphene oxide nanoparticle (GONP) decorated polypyrrole (Ppy) layer electrochemically deposited onto a fluorine doped tin oxide (FTO) glass plate.

Bilirubin removal performance of immobilized albumin in a magnetically stabilized fluidized bed

Human serum albumin (HSA)-immobilised magnetic poly(2-hydroxyethyl methacrylate) (mPHEMA) particles were investigated as an adsorbent for selective bilirubin removal from human plasma in a magnetically stabilized fluidized bed system. mPHEMA particles were prepared by suspension polymerization in the presence of Fe3O4 particles. mPHEMA particles were characterized by scanning electron microscopy (SEM), surface area and pore size measurements. The mPHEMA beads have a spherical shape and porous structure. The specific surface area of the mPHEMA particles was found to be 50 m2/g with a size range of 80-120 microm in diameter and the swelling ratio was 45%. Then, HSA was covalently coupled to the cyanogen bromide (CNBr)-activated mPHEMA particles. The amount of coupled HSA was arranged by changing the activation degree of particles (i.e., CNBr concentration). In vitro bilirubin removal was investigated from hyperbilirubinemic human plasma on the mPHEMA particles containing different amounts of immobilised HSA (between 11 and 100 mg/g). The non-specific bilirubin adsorption on the bare mPHEMA particles was 0.47 mg/g. Higher bilirubin adsorption capacities, up to 88.3 mg/g, were obtained with the HSA-immobilised magnetic particles. Bilirubin capacity decreased significantly from 75.0 mg/g to 40.0 mg/g polymer with the increase of the flow-velocity from 0.5 ml/min to 4.0 ml/min. Bilirubin adsorption increased with increasing temperature. Adsorption behavior of bilirubin could be modelled using the Langmuir isotherm.

Liver support devices

PURPOSE OF REVIEW

Liver support devices are used either as a bridge to liver transplantation or liver recovery in patients with acute or acute-on-chronic liver failure. The review analyzes the recent literature and asks if the current enthusiasm for these devices is justified.

RECENT FINDINGS

Many liver support devices exist and are discussed. Clinical data on artificial devices are rapidly emerging, especially on the molecular adsorbents recirculating system, and fractionated plasma separation and adsorption (Prometheus). While hepatic encephalopathy is improved by the molecular adsorbents recirculating system and probably Prometheus too, neither system has been shown to improve survival. Less clinical data exist for bioartificial support devices. These may use human hepatocytes, such as the extracorporeal liver assist device, although most devices use porcine hepatocytes, such as HepatAssist.

SUMMARY

Enthusiasm in liver support devices is justified as many nonrandomized studies have suggested some biochemical and clinical benefits. The results of several ongoing multicenter randomized controlled trials are anxiously awaited. Meanwhile, because mortality without liver transplantation remains high despite the use of liver support devices, these devices should only be used in the research setting or by experts proficient in their use and as a bridge to liver transplantation rather than liver recovery.

[Safety and efficacy of the MARS therapy applied by continuous renal replacement therapy (CRRT) monitors]

OBJECTIVE

Analyze the utility and safety of MARS therapy applied with the CRRT monitor.

DESIGN

Prospective study of cohorts.

SCOPE

Polyvalent ICU in tertiary university hospital with hepatic transplantation program.

PATIENTS

Thirty one patients: 9 (22.6%) with acute liver failure (ALF) (1 hepatic surgery, 1 primary graft failure, 7 other causes) and 22 (71%) with acute-on-chronic failure (AoCLF).

INTERVENTIONS

For the treatment, the patients with ALF are maintained in the ICU but those with AoCLF are admitted for the performance of the different sessions, that are programmed for a duration of at least 15 hours in AoCLF and in ALF are maintained continuously, changing the circuit every 24 hours.

VARIABLES OF INTEREST

Metabolic control and complications registered in 75 sessions on 31 patients.

RESULTS

Urea decrease was 33.5 (29-38%), creatinine 36 (31-41%), total bilirubin 29 (25-33%) and direct bilirubin 34 (30-38%). Clearance was slower, but sustained, after the first 4 hours of each session both for urea (p<0.001) as well as for bilirubin (p<0.05). The hemodynamic parameters improved and the hematological ones were not altered. We detected decrease in platelets (131 to 120x109/L, p<0.01). In 95 of the sessions in which heparin was used and in 6% where epoprostenol was used, we observed mild bleeding. We cultured albumin of the circuit at the end of the session in 50 occasions and only obtained growth in 3 cases (6%) (2 Staphylococcus epidermidis, 1 S. haemolyticus) without signs of contamination in the patients.

CONCLUSIONS

The MARS system applied by CRRT monitors provide adequate bilirubin clearance percentages and is safe, even in serious patients. Prolongation of the duration of the sessions was not accompanied by an increase in the risk of infection secondary to the albumin contamination.

Outcome from molecular adsorbent recycling system (MARS) liver dialysis following drug-induced liver failure

RATIONALE

Fulminant liver failure from drug ingestion is associated with a high mortality, and the introduction of liver transplantation has improved the mortality significantly if done in a timely fashion. Recently, molecular adsorbent recycling system (MARS) liver dialysis has been introduced as a support for liver failure with varying results. We review our experience with drug-induced liver failure and the impact of MARS liver dialysis on the outcome, in a setting where cadaveric liver transplantation is rarely available.

RESULTS

A total of 13 patients were treated, and 40 sessions of MARS liver dialysis were conducted in the intensive care unit. The majority of cases were because of herbal medicine toxicity. Total bilirubin, conjugated bilirubin, and delta bilirubin were significantly reduced, with no change in unconjugated bilirubin. All patients satisfied the criteria for urgent liver transplantation with an average Model End Stage Liver Disease (MELD) score of 35. Only one patient received a liver transplantation from a live donor (right lobe). Overall mortality was 85%. Median time-to-death from the start of MARS was 8 days.

CONCLUSIONS

MARS liver dialysis in a setting without timely liver transplantation is associated with a poor outcome. It does, however, provide a window of time for consideration of living donors in the setting of limited cadaveric donors.

Binding of bilirubin and bromosulphthalein to albumin: implications for understanding the pathophysiology of liver failure and its management

The binding/transporting functions of albumin provide the rationale for using albumin dialysis (e.g., molecular adsorbents recirculating system [MARS]) in liver failure. This study investigates these properties in vitro, validating the findings in vivo. In vitro bromosulphthalein (BSP) and bilirubin-spiked plasma were dialyzed against albumin and sampled. In vivo serum biochemistry was analyzed in: 7 MARS-treated liver failure patients; 98 MARS-treated patients from the MARS Registry; and 8 patients receiving albumin infusion. In vitro BSP concentrations did not equilibrate, but the molar ratio of BSP to albumin (C(BSP)/C(alb)) did, with no subsequent transmembrane transport, suggesting that the C(BSP)/C(alb) gradient (rather than simple diffusion) drives BSP transport. Bilirubin was transported similarly. In vivo serum bilirubin reduction during MARS sessions (n = 26) correlated with pre-treatment bilirubin (r = 0.42), but better (r = 0.85) with pre-treatment molar ratio of bilirubin to albumin (C(bilirubin)/C(alb)). The strongest correlation was between C(bilirubin)/C(alb) reduction and pre-treatment C(bilirubin)/C(alb) (r = 0.9). A similar pattern was observed in the MARS Registry patients. After albumin infusion (n = 8), both serum albumin and bilirubin increased, while C(bilirubin)/C(alb) remained unchanged. C(bilirubin)/C(alb) appears to be important in albumin dialysis, and generally in liver disease patients, reinforcing the importance of the toxin-binding functions of albumin in liver disease.

Extracorporeal liver support with molecular adsorbents recirculating system in patients with severe acute alcoholic hepatitis

BACKGROUND/AIMS

The mortality of patients with severe acute alcoholic hepatitis (AH) remains high, leading to interest in the use of extracorporeal liver support. The molecular adsorbents recirculating system (MARS) is a liver support device based upon a hollow fibre module in which the patient's blood is dialyzed across an albumin-impregnated membrane. The aim of this paper is to assess the safety, efficacy and feasibility of using MARS in patients with severe AH.

METHODS

Eight patients (all encephalopathic; hepatorenal syndrome: Type 1, five patients; Type 2, two patients) were treated with MARS. Clinical, biochemical and haemodynamic assessments were done.

RESULTS

Five patients were discharged from hospital, and four are alive at 3 months of follow-up, compared with an estimated survival of about 20%. There were significant improvement in serum bilirubin (P=0.008), creatinine (P=0.02), prothrombin time (P=0.04), and grade of encephalopathy (P=0.05). Sustained improvements in mean arterial pressure, systemic vascular resistance and cardiac output were observed. Thrombocytopaenia was the only MARS-related adverse event observed.

CONCLUSIONS

MARS resulted in improved liver biochemistry, cardiovascular haemodynamics, renal function and encephalopathy in patients with severe AH, with an apparent reduction in mortality. On this basis, a multi-centre, randomized clinical trial has been initiated.