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Wolfgang Domej,1 Karl Oettl,2 Wilfried Renner31Division of Pulmonology, Department of Internal Medicine, 2Institute of Physiological Chemistry, 3Clinical Institute of Medical and Chemical Diagnostics, Medical University of Graz, Graz, AustriaAbstract: Oxidative stress occurs when free radicals and other reactive species overwhelm the availability of antioxidants. Reactive oxygen species (ROS), reactive nitrogen species, and their counterpart antioxidant agents are essential for physiological signaling and host defense, as well as for the evolution and persistence of inflammation. When their normal steady state is disturbed, imbalances between oxidants and antioxidants may provoke pathological reactions causing a range of nonrespiratory and respiratory diseases, particularly chronic obstructive pulmonary disease (COPD). In the respiratory system, ROS may be either exogenous from more or less inhalative gaseous or particulate agents such as air pollutants, cigarette smoke, ambient high-altitude hypoxia, and some occupational dusts, or endogenously generated in the context of defense mechanisms against such infectious pathogens as bacteria, viruses, or fungi. ROS may also damage body tissues depending on the amount and duration of exposure and may further act as triggers for enzymatically generated ROS released from respiratory, immune, and inflammatory cells. This paper focuses on the general relevance of free radicals for the development and progression of both COPD and pulmonary emphysema as well as novel perspectives on therapeutic options. Unfortunately, current treatment options do not suffice to prevent chronic airway inflammation and are not yet able to substantially alter the course of COPD. Effective therapeutic antioxidant measures are urgently needed to control and mitigate local as well as systemic oxygen bursts in COPD and other respiratory diseases. In addition to current therapeutic prospects and aspects of genomic medicine, trending research topics in COPD are presented.Keywords: reactive oxygen species, reactive nitrogen species, chronic obstructive pulmonary disease, antioxidants

Dihydroneopterin has recently been shown to either promote or decrease formation of free radicals or radicalmediated reactions, depending on the conditions. We report here the scavenging activity of dihydroneopterin on nitrogen centered radicals. Diphenylpicrylhydrazyl (DPPH) and tl. e radical cation of 2,2' -azino-di-[3- ethylbenzthiazoline sulphonate] (ABTS) were used. Dihydroneopterin showed scavenging properties against either compound. In the case of DPPH radical scavenging by dihydroneopterin was comparable with trolox. In the ABTS system, dihydroneopterin had an even better capacity of radical scavenging as compared to trolox .

We describe the impact of dihydroneopterin on the formation of superoxide radicals. As radical source ferrous iron in air-saturated aequeous solution was used. Detection of superoxide was achieved using reduction of nitroblue tetrazolium to formazan. Dihydroneopterin decreases formazan formation when high concentrations of ferrous iron are used which induce a rapid superoxide formation within minutes. On the other hand, when low concentrations of ferrous iron are used, addition of dihydroneopterin to the assay mixture leads to an increase ir. formazan formation for several hours of incubation. We therefore conclude that the radical promoting activity of dihydroneopterin is physiologically more relevant compared to its radical scavenging properties.

Ab initio quantum chemical computations at the Hartree-Fock 6-31g** level of theory were performed on pterin, 7,8-dihydropterin and 5,6,7,8 -tetrahydropterin. The resulting electronic charge density functions and the electrostatic potential functions of the molecules are visualized by graphical software. The results demonstrate the profound changes in electronic properties among these structurally closely related compounds. Our contribution may serve as a basis for deeper insight into the molecular characteristics, also of other chemically or biologically important pterin derivatives of different oxidation state.

Oxidative albumin modification and impaired albumin binding function have been described both in chronic liver failure and for therapeutic albumin solutions. The aim of the present study was to evaluate the effect of albumin infusion on redox state and binding function of circulating albumin. We studied 20 patients with cirrhosis who routinely received albumin infusions for prevention of post-paracentesis circulatory dysfunction or treatment of hepatorenal syndrome. We measured albumin fractions by redox state of cysteine-34 and albumin binding properties using dansylsarcosine as site II ligand. Therapeutic albumin solutions showed high contents of human nonmercaptalbumin-1 and human nonmercaptalbumin-2, exceeding the respective values in our patients with decompensated cirrhosis. An initial protocol for the first nine patients sampled at baseline, 24 h and 48 h after albumin infusion revealed no significant changes of oxidized albumin species or albumin binding properties. However, a modified protocol for the remaining 11 patients sampled at baseline, <1 h after and 24 h after albumin infusion revealed short-lived changes of oxidized albumin species while no changes in albumin binding properties were observed. In conclusion, therapeutic albumin infusion transiently changed albumin redox state but did not improve binding function of circulating albumin in chronic liver failure., (© 2023 The Authors. Basic & Clinical Pharmacology & Toxicology published by John Wiley & Sons Ltd on behalf of Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).)

Background: Albumin, as the most abundant plasma protein, represents a target structure for both drug and physicochemical therapeutic approaches to eliminate uraemic toxins more efficiently. Potentially, this approach could reduce mortality of haemodialysis patients. However, little is known about albumin functional properties in these patients and its alteration by haemodialysis treatment., Methods: The binding and detoxification efficiency of albumin were assessed by electron paramagnetic resonance spectroscopy using a spin-labelled fatty acid. Binding efficiency (BE) reflects strength and amount of bound fatty acids under certain ethanol concentration. Detoxification efficiency (DTE) reflects the molecular flexibility of the patient's albumin molecule, thus the ability to change the conformation depending on ethanol concentration. Percentage of BE and DTE are depicted in relation to healthy individuals (100%)., Results: Fifty-eight patients (59% male, median age 68 years, median time on haemodialysis 32 months) were included in the study. Before haemodialysis treatment, albumin binding and detoxification efficiency were substantially below healthy individuals [median BE 52% (interquartile range, IQR, 45%-59%); median DTE 38% (IQR 32-49%)]. After haemodialysis treatment, median BE and DTE significantly decreased [BE 28% (IQR 20-41%); DTE 11% (IQR 7%-27%; P < .001)]. BE and DTE decline after haemodialysis was not dependent on age, sex or treatment modalities, but was to a certain extent on the level of non-esterified fatty acids., Conclusion: Albumin binding and detoxification efficiency of fatty acids in maintenance haemodialysis patients were substantially below those in healthy individuals and even declined after dialysis treatment. These findings might be helpful when considering new therapeutic approaches in maintenance haemodialysis patients., (© The Author(s) 2023. Published by Oxford University Press on behalf of the ERA.)

Oxidative stress is involved in the development, progression, and complications of diabetes mellitus (DM). Oxidative modification of human serum albumin's cysteine-34 is a marker for oxidative stress-related pathological conditions. We aimed to evaluate the redox state of albumin in patients with DM to investigate possible correlations with age, diabetes duration, and disease control status. Plasma aliquots were collected from 52 participants (26 type 1 and 26 type 2 DM). Patients were divided into two groups according to their glycated hemoglobin levels less than or equal to and greater than 58 mmol/L. Albumin redox state was assessed with high-performance liquid chromatography by fractionating it into human mercaptalbumin (HMA) and human nonmercaptalbumin 1 and 2 (HNA1 and HNA2). Albumin redox fractions were differently related to the age of study participants. In age-matched T1DM and T2DM groups, the albumin redox state was essentially the same. Irreversibly oxidized HNA2 was positively correlated with diabetes duration, especially in the T1DM group. HNA was increased in people with an increased HbA1c (>58 mmol/mol). Our results support the hypothesis that oxidative stress plays a crucial role in DM pathogenesis and emphasize the importance of diabetes control on systemic oxidative burden.

Background and Aim: Maintenance haemodialysis patients have increased morbidity and mortality which is mainly driven by an elevated inflammation level due to the uraemic milieu. A major part of this increased inflammation level is the degree of oxidative stress which can be assessed by albumin redox state (ARS). Aim of this study was to evaluate how the ARS is affected by a haemodialysis treatment and different dialyzer properties., Methods: ARS was determined before and after haemodialysis treatment by fractionating it into reduced human mercaptalbumin (HMA), reversibly oxidized human non-mercaptalbumin 1 (HNA-1), and irreversibly oxidized human non-mercaptalbumin 2 (HNA-2) by high-performance liquid chromatography. In healthy individuals, albumin circulates in the following proportions: HMA 70-80%, HNA-1 20-30% and HNA-2 2-5%. High flux (FX 100 [Fresenius Medical Care], BG 1.8 [Toray], Xevonta Hi 18 [B. Braun], CTA-2000 [Kawasumi]) and low flux FX10 [Fresenius Medical Care] dialyzers were used., Results: 58 patients (59% male, median age 68 years, median time on haemodialysis 32 month) were included in the study. Before haemodialysis treatment, HMA (median 55.9%, IQR 50.1-61.2%) was substantially lower than in healthy individuals. Accordingly, oxidized albumin fractions were above the level of healthy individuals (median HNA-1 38.5%, IQR 33.3-43.2%; median HNA-2 5.8%, IQR 5.1-6.7%). Before haemodialysis treatment HMA was significantly higher in patients usually treated with high flux membranes (p < 0.01). After haemodialysis treatment there was a significant increase of HMA and a decrease of HNA-1 and HNA-2 (p < 0.01). These effects were more pronounced in patients treated with high flux dialyzers (p < 0.01). There were no differences of ARS alteration with regard to the dialyzer´s sterilization mode or the presence of diabetes., Conclusion: The study confirms that the ARS is positively altered by haemodialysis and shows for the first time that this effect depends on dialyzer properties., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Background & Aims: Transport functions of albumin are of clinical and pharmacological interest and are determined by albumin's properties like posttranslational modifications or bound ligands. Both are affected in pathological conditions and in therapeutic grade albumin solutions. The term effective albumin concentration was introduced as a measure of functionally intact albumin. Our aim was to evaluate the impact of ligands and modifications with different approaches as a measure of effective albumin., Approach & Results: We used a spin labelled fatty acid and dansylsarcosine to characterize binding properties of albumin i) prepared from plasma of patients and healthy control donors, ii) measured directly out of plasma, iii) research grade albumin, iv) in vitro modified albumin, and v) therapeutic infusion solutions before and after removal of stabilizers. Bilirubin is the main determinant for binding function in patients' albumin. In in vitro prepared albumin bound fatty acids correlated with impaired binding. Human nonmercaptalbumin1, not human nonmercaptalbumin2, showed reduced binding properties. Binding and transport function of therapeutic albumin was severely impaired and restored by filtration. Glycation of research grade albumin had no effect on the binding of dansylsarcosine and only a minor effect on fatty acid binding., Conclusions: Our results suggest that effective albumin -in terms of binding properties- is primarily determined by bound ligands and only to a minor extent by posttranslational modifications. Characterizing albumin directly from plasma better reflects the physiological situation whereas in the case of therapeutic grade albumin stabilizers should be removed to make its binding properties accessible., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Karl Oettl is a consultant of Takeda Pharmaceuticals International AG., (Copyright © 2023. Published by Elsevier B.V.)

Background & Aims: Acute-on-chronic liver failure (ACLF) is characterized by severe systemic inflammation, multi-organ failure and high mortality rates. Its treatment is an urgent unmet need. DIALIVE is a novel liver dialysis device that aims to exchange dysfunctional albumin and remove damage- and pathogen-associated molecular patterns. This first-in-man randomized-controlled trial was performed with the primary aim of assessing the safety of DIALIVE in patients with ACLF, with secondary aims of evaluating its clinical effects, device performance and effect on pathophysiologically relevant biomarkers., Methods: Thirty-two patients with alcohol-related ACLF were included. Patients were treated with DIALIVE for up to 5 days and end points were assessed at Day 10. Safety was assessed in all patients (n = 32). The secondary aims were assessed in a pre-specified subgroup that had at least three treatment sessions with DIALIVE (n = 30)., Results: There were no significant differences in 28-day mortality or occurrence of serious adverse events between the groups. Significant reduction in the severity of endotoxemia and improvement in albumin function was observed in the DIALIVE group, which translated into a significant reduction in the CLIF-C (Chronic Liver Failure consortium) organ failure (p = 0.018) and CLIF-C ACLF scores (p = 0.042) at Day 10. Time to resolution of ACLF was significantly faster in DIALIVE group (p = 0.036). Biomarkers of systemic inflammation such as IL-8 (p = 0.006), cell death [cytokeratin-18: M30 (p = 0.005) and M65 (p = 0.029)], endothelial function [asymmetric dimethylarginine (p = 0.002)] and, ligands for Toll-like receptor 4 (p = 0.030) and inflammasome (p = 0.002) improved significantly in the DIALIVE group., Conclusions: These data indicate that DIALIVE appears to be safe and impacts positively on prognostic scores and pathophysiologically relevant biomarkers in patients with ACLF. Larger, adequately powered studies are warranted to further confirm its safety and efficacy., Impact and Implications: This is the first-in-man clinical trial which tested DIALIVE, a novel liver dialysis device for the treatment of cirrhosis and acute-on-chronic liver failure, a condition associated with severe inflammation, organ failures and a high risk of death. The study met the primary endpoint, confirming the safety of the DIALIVE system. Additionally, DIALIVE reduced inflammation and improved clinical parameters. However, it did not reduce mortality in this small study and further larger clinical trials are required to re-confirm its safety and to evaluate efficacy., Clinical Trial Number: NCT03065699., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Like in many other pathologies, oxidative stress is involved in the development of neurodegenerative disorders. Human serum albumin (HSA) is the main protein in different body fluids including cerebrospinal fluid (CSF). By its redox state in terms of cysteine-34, albumin serves as marker for oxidative burden. We aimed to evaluate the redox state of HSA in patients with multiple sclerosis in serum and CSF in comparison to controls to identify possible correlations with disease activity and severity. Samples were stored at -70 °C until analysis by HPLC for the determination of albumin redox state in terms of the fractions of human mercaptalbumin (HMA), human nonmercaptalbumin1 (HNA1), and human nonmercaptalbumin2 (HNA2). Albumin in CSF showed significantly higher fractions of the reduced form HMA and decreased HNA1 and HNA2. There was no difference between albumin redox states in serum of patients and controls. In CSF of patients HNA2 showed a trend to higher fractions compared to controls. Albumin redox state in serum was associated with physical disability in remission while albumin redox state in CSF was related to disease activity. Thus, albumin redox state in serum and CSF of patients in relation to disease condition merits further investigation.

Plasmapheresis (PE) is an established form of therapeutic apheresis (TA). Purpose of this longitudinal prospective single center study was to investigate the effect of PE on albumin redox state (ARS), as infusion of commercial albumin during PE may alter albumin oxidation which has an impact on its functional properties and oxidative stress level. 43 subjects with autoimmune-mediated neurological disorders were included. 20 subjects in the experimental group received five treatments of PE. 13 subjects received five treatments of immunoadsorption and 10 subjects received no TA as controls. ARS was determined before and after TA and 12 days after the last TA by fractionating it into human mercaptalbumin (HMA), human non-mercaptalbumin 1 (HNA-1), and human non-mercaptalbumin 2 (HNA-2) by high-performance liquid chromatography. Irreversibly oxidised HNA-2 increased over the course of five PE treatments from 2.8% (IQR 1.3-3.7%) to 13.6% (IQR 10.9-15.9) (P < 0.01) and remained elevated 12 days after the last PE procedure (7.7% IQR 7.1-10.5, P < 0.05). The study showed for the first time that PE exerts a severe and long-lasting alteration on ARS indicating a new adverse effect of PE, that may influence oxidative stress level., (© 2022. The Author(s).)

A quick literature search using "sex/gender" vs. the commonly used hypnotic propofol or neuromuscular-blocking agent cisatracurium will reveal numerous contradictory sex difference publications depending on the ethnic-geographic location of where these studies were conducted. We induced anesthesia with cisatracurium besylate (GlaxoSmithKline) 100 μg kg -1 administered exactly 1 minute following propofol (AstraZeneca) 2 mg kg -1 . In 20 male and 20 female ethnic Han-Chinese test set patients (Xi'an China), and in similar ethnic white Austrian validation set patients (Graz Austria), we quantified propofol/cisatracurium pharmacodynamic parameters namely propofol onset time, lag time, plasma concentrations (C p ) at loss-of-behavioral response (LOBR) using bispectral index (BIS); cisatracurium onset time, lag time, and C p at T 1 % (first twitch of train-of-four) complete twitch suppression using mechanomyography (MMG). Serial arterial blood samples were collected for population pharmacokinetic (PopPK) analysis of all demographic and biological covariates (region, sex, age, weight, and height) versus volumes of distribution and clearances pharmacokinetic parameters. In Chinese women (but not in white women), propofol C p at LOBR was 33.60% lower than men and cisatracurium C p at T 1 % complete twitch suppression was 21.49% lower than men, a clear pharmacodynamic assertion. Region and weight were significant PopPK covariates. We demonstrated that sex differences are influenced by ethnic-geographic location as only in Chinese women (but not in white women) propofol C p at LOBR and cisatracurium C p at T 1 % complete twitch suppression were lower than in men. When defining sex differences, ethnic-geographic location should be taken into consideration as a predictive factor for optimizing propofol/cisatracurium initial loading recommended dosages., (© 2021 Société Française de Pharmacologie et de Thérapeutique.)

Human serum albumin (HSA) constitutes the primary transporter of fatty acids, bilirubin, and other plasma compounds. The binding, transport, and release of its cargos strongly depend on albumin conformation, which is affected by bound ligands induced by physiological and pathological conditions. HSA is both highly oxidized and heavily loaded with fatty acids and bilirubin in chronic liver disease. By employing small-angle X-ray scattering we show that HSA from the plasma of chronic liver disease patients undergoes a distinct opening compared to healthy donors. The extent of HSA opening correlates with clinically relevant variables, such as the model of end-stage liver disease score, bilirubin, and fatty acid levels. Although the mild oxidation of HSA in vitro does not alter overall structure, the alteration of patients' HSA correlates with its redox state. This study connects clinical data with structural visualization of albumin dynamicity in solution and underlines the functional importance of albumin's inherent flexibility.