Mild Coronavirus Disease 2019 (COVID-19) Is Marked by Systemic Oxidative Stress: A Pilot Study

Oxidative stress has been implicated to play a critical role in the pathophysiology of coronavirus disease 2019 (COVID-19) and may therefore be considered as a relevant therapeutic target. Serum free thiols (R-SH, sulfhydryl groups) comprise a robust marker of systemic oxidative stress, since they are readily oxidized by reactive oxygen species (ROS). In this study, serum free thiol concentrations were measured in hospitalized and non-hospitalized patients with COVID-19 and healthy controls and their associations with relevant clinical parameters were examined. Serum free thiol concentrations were measured colorimetrically (Ellman’s method) in 29 non-hospitalized COVID-19 subjects and 30 age-, sex-, and body-mass index (BMI)-matched healthy controls and analyzed for associations with clinical and biochemical disease parameters. Additional free thiol measurements were performed on seven serum samples from COVID-19 subjects who required hospitalization to examine their correlation with disease severity. Non-hospitalized subjects with COVID-19 had significantly lower concentrations of serum free thiols compared to healthy controls (p = 0.014), indicating oxidative stress. Serum free thiols were positively associated with albumin (St. β = 0.710, p < 0.001) and inversely associated with CRP (St. β = −0.434, p = 0.027), and showed significant discriminative ability to differentiate subjects with COVID-19 from healthy controls (AUC = 0.69, p = 0.011), which was slightly higher than the discriminative performance of CRP concentrations regarding COVID-19 diagnosis (AUC = 0.66, p = 0.042). This study concludes that systemic oxidative stress is increased in patients with COVID-19 compared with healthy controls. This opens an avenue of treatment options since free thiols are amenable to therapeutic modulation.

Elevated plasma free thiols are associated with early and one-year graft function in renal transplant recipients

Background Reduced free thiols in plasma are indicative of oxidative stress, which is an important contributor to ischaemia-reperfusion injury (IRI) in kidney transplantation leading to kidney damage and possibly delayed graft function (DGF). In a post-hoc, exploratory analysis of the randomised controlled CONTEXT trial, we investigated whether higher (i.e. less oxidised) plasma levels of free thiols as a biomarker of reduced oxidative stress are associated with a better initial graft function or a higher GFR. Methods Free thiol levels were measured in plasma at baseline, 30 and 90 minutes after reperfusion of the kidney as well as at Day 1, Day 5 and twelve months after kidney transplantation in 217 patients from the CONTEXT study. Free thiol levels were compared to the kidney graft function measured as the estimated time to a 50% reduction in plasma creatinine (tCr50), the risk of DGF and measured GFR (mGFR) at Day 5 and twelve months after transplantation. Results Higher levels of free thiols at Day 1 and Day 5 are associated with higher mGFR at Day 5 (p<0.001, r2adj. = 0.16; p<0.001, r2adj. = 0.25), as well as with mGFR at twelve months (p<0.001, r2adj. = 0.20; p<0.001, r2adj. = 0.16). However, plasma levels of free thiols at 30 minutes and 90 minutes, but not Day 1, were significantly higher among patients experiencing DGF. Conclusion Higher levels of plasma free thiols at Day 1 and Day 5, which are reflective of lower levels of oxidative stress, are associated with better early and late graft function in recipients of a kidney graft from deceased donors. Trial registration ClinicalTrials.gov Identifier: NCT01395719.

A new insight into aggregation of oncolytic adenovirus Ad5-delta-24-RGD during CsCl gradient ultracentrifugation

Two-cycle cesium chloride (2 × CsCl) gradient ultracentrifugation is a conventional approach for purifying recombinant adenoviruses (rAds) for research purposes (gene therapy, vaccines, and oncolytic vectors). However, rAds containing the RGD-4C peptide in the HI loop of the fiber knob domain tend to aggregate during 2 × CsCl gradient ultracentrifugation resulting in a low infectious titer yield or even purification failure. An iodixanol-based purification method preventing aggregation of the RGD4C-modified rAds has been proposed. However, the reason explaining aggregation of the RGD4C-modified rAds during 2 × CsCl but not iodixanol gradient ultracentrifugation has not been revealed. In the present study, we showed that rAds with the RGD-4C peptide in the HI loop but not at the C-terminus of the fiber knob domain were prone to aggregate during 2 × CsCl but not iodixanol gradient ultracentrifugation. The cysteine residues with free thiol groups after the RGD motif within the inserted RGD-4C peptide were responsible for formation of the interparticle disulfide bonds under atmospheric oxygen and aggregation of Ad5-delta-24-RGD4C-based rAds during 2 × CsCl gradient ultracentrifugation, which could be prevented using iodixanol gradient ultracentrifugation, most likely due to antioxidant properties of iodixanol. A cysteine-to-glycine substitution of the cysteine residues with free thiol groups (RGD-2C2G) prevented aggregation during 2 × CsCl gradient purification but in coxsackie and adenovirus receptor (CAR)-low/negative cancer cell lines of human and rodent origin, this reduced cytolytic efficacy to the levels observed for a fiber non-modified control vector. However, both Ad5-delta-24-RGD4C and Ad5-delta-24-RGD2C2G were equally effective in the murine immunocompetent CT-2A glioma model due to a primary role of antitumor immune responses in the therapeutic efficacy of oncolytic virotherapy.

Systemic Oxidative Stress, Aging and the Risk of Cardiovascular Events in the General Female Population

Introduction: Menopause is associated with increased cardiovascular risk, in which oxidative stress plays a pivotal role. Systemic oxidative stress is reflected by decreased levels of free thiols (R-SH, sulfhydryl groups), which are key components of the extracellular antioxidant machinery. In this study, we investigated the relation between serum free thiols as marker of oxidative stress and the female cardiovascular phenotype, as well as potential associations with the risk of cardiovascular (CV) events in pre- and postmenopausal women from the general population.Methods: Female participants (n = 2,980) of the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) cohort study were included. Serum free thiol concentrations were analyzed for associations with demographic, clinical, biochemical, and gynecological parameters, as well as with menopausal status and, prospectively, with the risk of CV events.Results: Postmenopausal women had significantly reduced levels of serum free thiols (4.8 ± 1.0 vs. 5.2 ± 1.0 μmol/g, P &lt; 0.001) compared to reproductive women. In multivariable analyses, serum free thiols were significantly associated with menopausal status (OR 0.70 [0.49–0.98], P = 0.039), even when adjusted for potential confounding factors, except for age (P = 0.550). Prospectively, serum free thiols were significantly associated with the risk of CV events (HR 0.52 [0.27–0.97], P = 0.040), even with covariate adjustment, although this disappeared when correcting for age.Conclusion: In this study, we revealed serum free thiols to be strongly associated with the female cardiovascular phenotype as well as with female risk of CV events, where the influence of age itself seemed to outweigh that of female menopause. Future studies are warranted to further unravel the clinical utility of serum free thiol levels in the context of female cardiovascular risk management.

Effects of vitamin E, an oil blend and L-Arginine on breast meat from broiler chickens

The study examined the effects of supplementing vitamin E on the fatty acid profile and breast meat quality of broilers fed diets containing an oil blend and L-Arginine. Two hundred sixteen Cobb 500 one-day-old broilers were randomly allocated to six treatments, namely T1: 6% palm oil (control); T2: blend of 4% palm oil and 2% sunflower oil + 0.25% L-Arginine (positive control); T3: T2 with 20 mg/kg vitamin E added; T4: T2 with 50 mg/kg vitamin E added; T5: T2 with 100 mg/kg vitamin E added; and T6: T2 supplemented with 150 mg/kg vitamin E. Relative to T1, the other diets increased growth rate and improved feed conversion ratio (FCR) similarly. Linoleic, arachidonic, and polyunsaturated fatty acids were greater and palmitic and saturated fatty acids were lower in the meat of birds fed T2–T6 relative to T1. Supplementation of vitamin E reduced drip loss (DL) and increased redness, tenderness, free thiol content, and the oxidative stability of meat during storage at 4 °C. Regardless of diet, free thiol, redness and Warner-Bratzler shear force (WBSF) value decreased significantly, whereas the carbonyl content, thiobarbituric acid-reactive substances (TBARS), and DL of breast meat increased over the ageing period. In conclusion, relative to T1, the other diets were effective in improving growth performance and meat quality during post-mortem storage Key words: fatty acid profile, free thiol, lipid oxidation, palm oil, protein oxidation, sunflower oil

Selective removal of toxic organic dyes using Trӧger base-containing sulfone copolymers made from a metal-free thiol-yne click reaction followed by oxidation

Copolymers TCP1–3 with Trӧger's base units and aryl thioether groups were made via a click reaction. Selective oxidation of the thioethers into sulfone groups afforded TCP4–6 which display up to 100% removal efficiency of methylene blue from water.