Procedure-related pulmonary hypertension in patients with hepatocellular carcinoma undergoing percutaneous ethanol injection—Role of ethanol, hemolysis, asymmetric dimethylarginine, and the nitric oxide system:

Physiological role of plasma and its components and the clinical implications of different methods of apheresis: A narrative review

Nowadays, therapeutic plasmapheresis (TP) is accepted as part of the treatment for specific groups of diseases. The availability of different methods, including double filtration and adsorption, increases selectivity for the removal of substances. However, the use of these techniques requires a thorough understanding of the characteristics and components of plasma. By considering pivotal papers from several databases, the aim of this narrative review is to describe the characteristics of plasma related to apheresis techniques. We have tried to cover the clinical implications including physiology, estimation of plasma volume, viscosity, and a description of its components including the size, volume of distribution, and half-lives of the different substances to be removed or maintained depending on the clinical situation and applied apheresis technique. Applying this knowledge will help us to choose the right method and dosage and improve the efficacy of the procedure by preventing or addressing any complications.

Dimethylarginines ADMA and SDMA: the real water-soluble small toxins?

Uremia occurs if the kidney loses the ability to eliminate toxic compounds at a sufficient rate into the urine. In 1970, N-N, N-G- and N-G,N׳-G-dimethyl-arginine (asymmetric dimethylarginine [ADMA] and symmetric dimethylarginine) were isolated from human urine. It was anticipated that both substances might be important in the pathophysiology and for the diagnosis of various pathologic states. It took 22 years, however, before this idea materialized when it was found that ADMA, which is increased in hemodialysis patients, inhibits the synthesis of the endothelial-derived relaxing factor, identified as nitric oxide. ADMA correlates with traditional and nontraditional cardiovascular risk factors and is a strong predictor of cardiovascular events and death in both patients with chronic kidney disease and in the general population. It also seems to mediate adverse cardiovascular effects of drugs such as proton pump inhibitors. To date, we have no specific pharmacologic therapy at hand to neutralize the deleterious effects of ADMA, curbing the enthusiasm for this marker and mediator of cardiovascular disease.

Acute cor pulmonale and right heat failure complicating ethanol ablative therapy: anesthetic and radiologic considerations and management

Ethanol is an effective ablative agent used for the treatment of certain solid organ tumors and vascular malformations (VMs). The egress of ethanol beyond the target tissue can be associated with significant changes to the cardiopulmonary system that can lead to cardiac arrest. This article reviews the contemporary role of ethanol in tumor and VM treatment and discusses the physiological mechanisms of acute pulmonary hypertension and cardiovascular collapse. The importance of periprocedural recognition of the hemodynamic changes that can occur with the use of ethanol and the treatment of this condition are discussed.

Spectroscopic and Calorimetric Evaluation of Chemically Induced Protein Denaturation in HuH-7 Liver Cancer Cells and Impact on Cell Survival

Solid tumors such as hepatocellular carcinoma are very often not amenable to chemotherapy and radiotherapy. Local ablation methods, including chemical ablation with absolute ethanol, are therefore an option for treatment but lack of information about the mechanism of devitalization leading to cell death is a hindrance to further adoption. Systemic toxicity also has limited the amount of ethanol that can be used in a single treatment session. Therefore we evaluated the mechanism of urea, a denaturant with little or no systemic toxicity, for potential use in chemical ablation. In this study we report on the use of three methods to analyze the effects in cell culture with a view towards eventual clinical application. Human hepatoma HuH-7 cells were analyzed at several time points after treatment using FTIR, DSC, and Raman microspectroscopy based on MTT and PI-exclusion viability assays. Time course fractional denaturation data plotted against viability show that a 50% viability drop occurs after only a 10–20% drop in overall protein denaturation. Other methods of cell death such as apoptosis may also be operative, but this result implies that protein denaturation is one of the major mechanisms of cell death. This is in line with what has been previously suggested for purely thermal methods, and opens the way to mechanism-based improvements in chemical ablation of solid tumors.

Unilateral nephrectomy causes an abrupt increase in inflammatory mediators and a simultaneous decrease in plasma ADMA: a study in living kidney donors

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthases (NOS). Reducing inducible NOS activity in acute inflammation seems to be desirable. In vitro data show that ADMA increases in response to inflammatory mediators, yet the effect of acute inflammation in vivo is scarcely studied. The aim of the study was to evaluate ADMA plasma levels before, during, and after the acute (nonbacterial) inflammatory-like state. Plasma ADMA, l-arginine, C-reactive protein, and IL-6 were determined in 24 healthy subjects undergoing living related kidney donation before as well as 1, 6, 12, 24, 72, and 168 h thereafter. Six hours after nephrectomy, ADMA levels decreased compared with baseline (0.488 ± 0.075 vs. 0.560 ± 0.060 μmol/l, P < 0.05). This difference became even more marked 24 h after the operation (0.478 ± 0.083 μmol/l, P < 0.01 vs. baseline), when the proinflammatory cytokine IL-6 peaked. Seven days after unilateral nephrectomy, ADMA levels were elevated above baseline (0.63 ± 0.05 μmol/l, P < 0.001 vs. baseline). l-Arginine levels decreased already 1 h after nephrectomy (97.5 ± 22.5 μmol/l, P < 0.01 vs. baseline) and paralleled the change in ADMA thereafter. At the end of the observation period when inflammation markers were regressing, l-arginine levels were significantly elevated above baseline (160.6 ± 25.1 μmol/l, P < 0.001 vs. baseline). In summary, this is the first study showing that both ADMA and l-arginine decrease temporarily after unilateral nephrectomy coinciding with the increase in inflammatory mediators. The l-arginine/ADMA ratio, a surrogate for NO production capacity, was only altered for <24 h.

High permeability dialysis membrane allows effective removal of myoglobin in acute kidney injury resulting from rhabdomyolysis

OBJECTIVE

The objective of this study was to test the ability of myoglobin removal of a novel, high-permeability polysulphone dialyzer in acute kidney injury as a result of rhabdomyolysis.

SETTING

Intensive care unit of a tertiary care hospital.

PATIENTS

Six patients (one female; aged 24, 36, 41, 55, 63, and 65 yrs) with oligoanuric acute kidney injury resulting from rhabdomyolysis.

INTERVENTIONS

Extended dialysis was performed using a single-pass batch dialysis system and a novel polysulphone high-flux dialyzer (effective surface area 1.8 m; inner lumen 220 μm; wall thickness 35 μm; allowing elimination of substances with a molecular weight of up to 30 kDa).

MEASUREMENTS AND MAIN RESULTS

Samples were collected at prefilter and postfilter sites as well as from the collected spent dialysate. The dialyzer clearance was calculated from concentrations before and directly after the dialysis membrane, the blood flow, and the ultrafiltration rate. The total amount of the myoglobin removed was measured directly as the whole dialysate was preserved. A median myoglobin clearance of 90.5 mL/min (range, 52.4-126.3 mL/min) was achieved, resulting in a median myoglobin removal per treatment hour of 0.54 g (range, 0.15-2.21 g).

CONCLUSIONS

Extended dialysis with a high-flux, high-permeability membrane allowed effective elimination of myoglobin with a clearance of myoglobin that surpassed all previously reported dialysis techniques. This membrane may be advantageous in preventing acute kidney injury or avoiding complete loss of kidney function in patients with rhabdomyolysis. Further studies are needed to determine whether improving renal recovery or mortality in patients with acute kidney injury resulting from rhabdomyolysis is possible.

Removal of asymmetric dimethylarginine during artificial liver support using fractionated plasma separation and adsorption

OBJECTIVE

Asymmetric dimethylarginine (ADMA) is the most potent endogenous nitric oxide synthase inhibitor. Elevated ADMA levels have been linked to increased mortality in different patient populations. Key regulation of ADMA levels mainly takes place in the liver. Hence, ADMA is elevated in liver disease. There is no specific pharmacological treatment to lower the elevated ADMA levels. Hemodialysis is of limited efficiency in removing ADMA as it is highly protein bound. Prometheus is an extracorporeal liver support system which allows the removal of protein-bound toxins. We assessed the efficiency of the Prometheus system in reducing high ADMA levels in patients with liver failure.

MATERIAL AND METHODS

We studied nine patients with acute-on-chronic liver failure and concomitant renal failure already necessitating hemodialysis. Seven patients needed intensive care treatment. Two consecutive sessions of Prometheus therapy of each 4 h were performed in all patients. ADMA and its structural isomer symmetrical dimethylarginine (SDMA) were determined using liquid chromatography-mass spectrometry.

RESULTS

ADMA levels correlated to model for end stage liver disease (MELD) score (r(s) = 0.62; p < 0.0001). Before Prometheus was started, levels of ADMA and SDMA were elevated (1.36 +/- 0.5 micromol/l and 1.90 +/- 0.4 micromol/l, respectively). During Prometheus treatments, plasma levels of ADMA dropped by a mean 25% (p < 0.0001) and SDMA levels by 22% (p < 0.0001). However, there was a significant rebound of ADMA levels between the two therapy sessions (p < 0.01).

CONCLUSIONS

This study shows for the first time that plasma levels of ADMA can be effectively lowered by an artificial liver support system (Prometheus). Effective elimination of ADMA might explain some of the beneficial clinical effects of these systems in patients with liver failure.