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As in other fields, chronotherapy applied to arterial hypertension (AHT) may have implications on oxidative stress. We compared the levels of some redox markers between hypertensive patients with morning and bedtime use of renin-angiotensin-aldosterone system (RAAS) blockers. This was an observational study that included patients older than 18 years with a diagnosis of essential AHT. Blood pressure (BP) figures were measured using twenty-four-hour ambulatory BP monitoring (24-h ABPM). Lipid peroxidation and protein oxidation were assessed using the thiobarbituric acid reactive substances (TBARS) and reduced thiols assays. We recruited 70 patients with a median age of 54 years, of whom 38 (54%) were women. In hypertensive patients with bedtime use of RAAS blockers, reduced thiol levels showed a positive correlation with nocturnal diastolic BP decrease. TBARS levels were associated with bedtime use of RAAS blockers in dipper and non-dipper hypertensive patients. In non-dipper patients, bedtime use of RAAS blockers was also associated with a decrease in nocturnal diastolic BP. Chronotherapy applied to bedtime use of some BP-lowering drugs in hypertensive patients may be linked to a better redox profile. [ABSTRACT FROM AUTHOR]

An impaired nocturnal decrease in diastolic blood pressure (DBP) increases the blood pressure (BP) load, which is a main factor in endothelial dysfunction, atherosclerosis, and arterial stiffness. We aimed to quantify some markers of oxidative stress in hypertensive patients, to compare their levels between individuals with dipper and non-dipper DBP profiles, and to assess their correlation with the nocturnal DBP (nDBP) dipping. It was an observational study that included patients older than 18 years with a diagnosis of essential hypertension who consented to participate. The collected variables were some indices of 24-h ambulatory blood pressure monitoring, demographic, epidemiological, clinical, and laboratory variables. Plasma thiobarbituric acid reactive substances (TBARS) and reduced thiols, together with serum vitamin E, vitamin A, copper (Cu), and zinc (Zn) levels were assessed as oxidative stress markers. We recruited 248 patients with a median age of 56 years (56% women). The percentage of nDBP dipping showed a weak positive correlation with reduced thiol, vitamin E, and vitamin A levels; and a weak negative correlation with Cu levels. We also found a negative correlation between nDBP dipping and the TBARS/Thiol, TBARS/Vitamin E, and TBARS/Vitamin A ratios. After multivariate analysis, we found that increased TBARS/Thiol ratio and serum Cu levels were associated with a higher risk of a non-dipper DBP profile. As in other situations of increased cardiovascular risk, an impaired nDBP decrease may coincide with abnormalities in redox status. [ABSTRACT FROM AUTHOR]

Herein, we presented a review to show that the main mechanism underlying endothelial dysfunction is a decrease in the formation and bioavailability of NO against the background of inhibition of eNOS expression and reduced equivalents of the thiol-disulfide system with a simultaneous increase in the levels of cytotoxic forms of NO and the production of powerful vasoconstrictors. Based on the foregoing, the conjugated complex eNOS-L-arginine-NO/SH can be undoubtedly claimed in the near future as a promising target for the pharmacological correction of endothelial dysfunction. Since it is a nitrosative stress that plays the role in the development of endothelial dysfunction, it is topical to search for potential endothelial protectors in the series of S-substituted 1,2,4-triazole, which have the properties of antioxidanitts and NO scavengers. A striking representative of this cohort is Thiotriazolin which is a drug with cardioprotective, anti-ischemic and antioxidant properties, though does not possesses endothelial protective activity. As a result of chemical modification of the molecule of the latter, we obtained the compound (S)-2,6-diaminohexanoic acid 3-methyl-1,2,4-triazolyl-5-thioacetate (Angiolin), which manifests endothelium-protective properties against the background of cardioprotective, anti-ischemic and antioxidant activities. [ABSTRACT FROM AUTHOR]

As in other fields, chronotherapy applied to arterial hypertension (AHT) may have implications on oxidative stress. We compared the levels of some redox markers between hypertensive patients with morning and bedtime use of renin-angiotensin-aldosterone system (RAAS) blockers. This was an observational study that included patients older than 18 years with a diagnosis of essential AHT. Blood pressure (BP) figures were measured using twenty-four-hour ambulatory BP monitoring (24-h ABPM). Lipid peroxidation and protein oxidation were assessed using the thiobarbituric acid reactive substances (TBARS) and reduced thiols assays. We recruited 70 patients with a median age of 54 years, of whom 38 (54%) were women. In hypertensive patients with bedtime use of RAAS blockers, reduced thiol levels showed a positive correlation with nocturnal diastolic BP decrease. TBARS levels were associated with bedtime use of RAAS blockers in dipper and non-dipper hypertensive patients. In non-dipper patients, bedtime use of RAAS blockers was also associated with a decrease in nocturnal diastolic BP. Chronotherapy applied to bedtime use of some BP-lowering drugs in hypertensive patients may be linked to a better redox profile.

Asymmetrical flow field-flow fractionation (AF4) efficiently separates various macromolecules and nano-components of natural waters according to their hydrodynamic sizes. The online coupling of AF4 with fluorescence (Fluo) and UV absorbance (UV) detectors (FluoD and UVD, respectively) and inductively coupled plasma–mass spectrometry (ICP-MS) provides multidimensional information. This makes it a powerful tool to characterize and quantify the size distributions of organic and inorganic nano-sized components and their interaction with trace metals. In this study, we developed a method combining thiol labeling by monobromo(trimethylammonio)bimane bromide (qBBr) with AF4–FluoD to determine the size distribution and the quantities of thiols in the macromolecular dissolved organic matter (DOM) present in highly colored DOM-rich water sampled from Shuya River and Lake Onego, Russia. We found that the qBBr-labeled components of DOM (qB-DOM) were of humic type, characterized by a low hydrodynamic size (dh

P-Glycoprotein (P-gp) is one of the most clinically significant representatives of the ABC transporter superfamily due to its participation in the transport of biotic components and xenobiotics across the plasma membrane. It is known that various chemicals, environmental factors, and pathological processes can affect P-gp activity and expression. In this study, we investigated the role of P-gp in limiting the cell membrane permeability during oxidative stress. Human adenocarcinoma colon cells (Caco-2) overexpressing P-gp were cultured for 72 h in the medium containing hydrogen peroxide (0.1-50 µM). The transport of the P-gp substrate fexofenadine was evaluated in a special Transwell system. The amounts of P-gp and Nrf2 transcription factor were analyzed by the enzyme-linked immunosorbent assay. The concentration of SH-groups in proteins and the contents of lipid peroxidation products and protein carbonyl derivatives were determined spectrophotometrically. Hydrogen peroxide at a concentration of 0.1-5 µM did not significantly affect the studied parameters, while incubation with 10 µM H2O2 decreased in the level of SH groups in cell lysates and increased in the amount of Nrf2 in the cell lysates. Nrf2, in its turn, mediated an increase in the content and activity of the P-gp transporter, thus limiting the increasing permeability of the cell membrane. Hydrogen peroxide at a concentration of 50 µM promoted oxidative stress, which was manifested as a decrease in the content of SH-groups, increase in the concentration of lipid peroxidation products and protein carbonyl derivatives, and decrease in the P-gp level, which led to a significantly increased permeability of the plasma membrane. These results show that the transport and protective roles of P-gp, in particular, reduction of the cell membrane permeability, are affected by the intensity of oxidative stress and can be manifested only if the extent of membrane damage is insignificant. [ABSTRACT FROM AUTHOR]

Abstract Oxidative stress plays a pivotal and early role in the pathophysiology of Alzheimer's disease (AD). There is convincing evidence that oxidative alterations in AD and in mild cognitive impairment (MCI) patients are not limited to the brain but are extended to the blood compartment. However, the oxidative pattern in plasma is still inconclusive. Moreover, their potential association with the clinical scores MMSE (Mini-Mental State Examination) and MoCA (Montreal Cognitive Assessment) is poorly investigated. The aim of our study was to establish a pattern of blood-based redox alterations in prodromal AD and their evolution during the progression of the disease. Our results showed a reduction in the total antioxidant capacity (TAC) and an increase of the stress-response proteins apolipoprotein J (ApoJ) and Klotho in MCI subjects. For the first time, we evidenced circulating-proteasome activity. We found that the alteration of the circulating-proteasome activity is associated with the accumulation of oxidized proteins in plasma form early AD. Interestingly, the TAC, the levels of vitamin D and the activity of proteasome were positively associated to the clinical scores MMSE and MoCA. The levels of protein carbonyls and of ApoJ were negatively associated to the MMSE and MoCA scores. The levels of apolipoprotein D (ApoD) were not different between groups. Interestingly, the receiver operating characteristic (ROC) curves analysis indicated that these redox markers provide a fair classification of different groups with high accuracy. Overall, our results strengthen the notion that some specific oxidative markers could be considered as non-invasive blood-based biomarkers for an early MCI diagnosis and AD progression. Graphical abstract fx1 Highlights • Early Impairment of the plasma ability to degrade H2O2 in MCI patients. • Rise of some stress‐response proteins from the MCI status. • Inverse correlation between the circulating‐proteasome activity and protein oxidation in AD plasma. • Some plasma oxidative markers are linked to cognitive scores (MoCA and MMSE). • A combination of oxidative markers can be considered for the MCI diagnosis and the progression of AD. [ABSTRACT FROM AUTHOR]

Abstract: The water-soluble poly(allylamine hydrochloride)-wrapped multiwall carbon nanotubes (MWNT-PAH) can be obtained for the first time relying on the function of barbital, which provides a useful avenue for carbon nanotube application in material science and biosensor technology. The MWNT-PAH/horseradish peroxidase (HRP) bionanomultilayer was prepared via layer-by-layer (LBL) assembly. Atomic force microscopy, scanning electron microscopy and UV–vis spectra were adopted to monitor the uniform LBL assembly of the homogeneous bionanomultilayer. The bionanomultilayer was developed and constructed as a biosensor for the determination of reduced thiols based on the inhibition principle. Under the optimal conditions, the biosensor presented a linear response for glutathione (GSH) and cysteine (CSH) from 0.5 to 41.0μM (R =0.9983, n =12) and 0.4 to 28.8μM (R =0.9991, n =9), respectively. The limits of detection (S/N=3) for GSH and CSH were 0.09 and 0.06μM, respectively. A series of reduced thiols such as GSH, CSH, cysteamine, mercaptans and 3-mercapto-1-propanesulfonic acid (MPS) were selectively detected by the bionanomultilayer biosensor, while oxidized thiols showed no effect on the current response of the biosensor. [Copyright &y& Elsevier]

Abstract: Thiol (SH) groups play a remarkable role in the cell with their redox state affecting the activity and structure of many enzymes, receptors and transcription factors. In the present work, carbon paste electrodes modified with sulfhydryl oxidase (SOX) were prepared. The proposed biosensor was based on the monitoring of the produced peroxide concentration that correlates with the concentration of reduced thiols during the enzymatic reaction. As well as analytical characteristics, optimization in terms of amount of enzyme, pH and temperature were carried out. After that, thiolic compounds (reduced/oxidized glutathione, cysteine, homocysteine, N-acetylcysteine, dl-dithiotreitol) were separated by HPLC and the performance of the sulfhydril oxidase SOX biosensor as a post-column electrochemical detector was investigated for the analysis of these compounds. All data were given as a comparison of two systems; biosensor and diode array detector (DAD). [Copyright &y& Elsevier]

Abstract: The bilayer of Con A/HRP through the biospecific affinity of concanavalin A (Con A) and glycoprotein horseradish peroxidase (HRP) was prepared on the surface of an Au electrode modified by the precursor film consisted of poly(allylamine hydrochloride) poly(sodium-p-styrene-sulfonate). Atomic force microscopy and electrochemical impedance spectroscopy were adopted to monitor the uniform layer-by-layer assembly of the Con A/HRP bilayers. The amperometric measurement was based on the inhibition of reduced thiols and performed in the presence of the electron mediator hydroquinone in 0.2M phosphate buffer of pH 6.5 at an applied potential of −0.15V versus Ag/AgCl. Under the optimal conditions, the biosensor presented a linear response for cysteine from 0.1 to 23.5μM, with a detection limit of 0.02μM. The biosensor demonstrated high stability and repeatability. A series of reduced thiols were detected by this inhibition biosensor and oxidized thiols showed no effect on the current response of the biosensor. [Copyright &y& Elsevier]

Asymmetrical flow field-flow fractionation (AF4) efficiently separates various macromolecules and nano-components of natural waters according to their hydrodynamic sizes. The online coupling of AF4 with fluorescence (Fluo) and UV absorbance (UV) detectors (FluoD and UVD, respectively) and inductively coupled plasma-mass spectrometry (ICP-MS) provides multidimensional information. This makes it a powerful tool to characterize and quantify the size distributions of organic and inorganic nano-sized components and their interaction with trace metals. In this study, we developed a method combining thiol labeling by monobromo(trimethylammonio)bimane bromide (qBBr) with AF4-FluoD to determine the size distribution and the quantities of thiols in the macromolecular dissolved organic matter (DOM) present in highly colored DOM-rich water sampled from Shuya River and Lake Onego, Russia. We found that the qBBr-labeled components of DOM (qB-DOM) were of humic type, characterized by a low hydrodynamic size ( d h  < 2 nm), and have concentrations <0.3 μM. After enrichment with mercury, the complexes formed between the nano-sized components and Hg were analyzed using AF4-ICP-MS. The elution profile of Hg followed the distribution of the UV-absorbing components of DOM, characterized by slightly higher sizes than qB-DOM. Only a small proportion of Hg was associated with the larger-sized components containing Fe and Mn, probably inorganic oxides that were identified in most of the samples from river to lake. The size distribution of the Hg-DOM complexes was enlarged when the concentration of added Hg increased (from 10 to 100 nM). This was explained by the presence of small iron oxides, overlapping the size distribution of Hg-DOM, on which Hg bound to a small proportion. In addition, to provide information on the dispersion of macromolecular thiols in colored DOM-rich natural water, our study also illustrated the potential of AF4-FluoD-UVD-ICP-MS to trace or quantify dynamic changes while Hg binds to the natural nano-colloidal components of surface water., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Worms, Kavanagh, Moulin, Regier and Slaveykova.)