Plasma Virome of HIV-infected Subjects on Suppressive Antiretroviral Therapy Reveals Association of Differentially Abundant Viruses with Distinct T-cell Phenotypes and Inflammation.

Background: The plasma virome represents the overall composition of viral sequences present in it. Alteration in plasma virome has been reported in treatment naïve and immunocompromised (CD4 count < 200) people with HIV (PWH). However, the effect of ART on virome composition in PWH on ART with preserved CD4 counts is poorly understood. Objectives: We aimed to assess the alterations in plasma virome in PWH on ART in comparison to HIV-negative uninfected controls and to further investigate possible associations of plasma viruses with inflammation and immune dysfunction, namely, immunosenescence and immune exhaustion. Methods: Plasma viral DNA from PWH on ART and controls was used for sequencing on the Illumina Nextseq500 platform, followed by the identification of viral sequences using an automated pipeline, VIROMATCH. Multiplex cytokine assay was performed to measure the concentrations of various cytokines in plasma. Immunophenotyping was performed on PBMCs to identify T cell markers of immunosenescence and immune exhaustion. Results: In our observational, cross-sectional pilot study, chronically infected PWH on ART had significantly different viral species compositions compared to controls. The plasma virome of PWH showed a significantly high relative abundance of species Human gammaherpesvirus 4, also known as Epstein-Barr virus (EBV). Moreover, EBV emerged as a significant viral taxon differentially enriched in PWH on ART, which further correlated positively with the exhaustion phenotype of T cells and significantly increased TNF-α in PWH on ART. Additionally, a significantly increased proportion of senescent T cells and IL-8 cytokine was detected in PWH on ART. Conclusion: Altered plasma virome influenced the inflammatory response and T-cell phenotype in PWH on ART.

Mutants of Cytochrome P450 Reductase Lacking Either Gly-141 or Gly-143 Destabilize Its FMN Semiquinone.

NADPH-cytochrome P450 oxidoreductase transfers electrons from NADPH to cytochromes P450 via its FAD and FMN. To understand the biochemical and structural basis of electron transfer from FMN-hydroquinone to its partners, three deletion mutants in a conserved loop near the FMN were characterized. Comparison of oxidized and reduced wild type and mutant structures reveals that the basis for the air stability of the neutral blue semiquinone is protonation of the flavin N5 and strong H-bond formation with the Gly-141 carbonyl. The ΔGly-143 protein had moderately decreased activity with cytochrome P450 and cytochrome c It formed a flexible loop, which transiently interacts with the flavin N5, resulting in the generation of both an unstable neutral blue semiquinone and hydroquinone. The ΔGly-141 and ΔG141/E142N mutants were inactive with cytochrome P450 but fully active in reducing cytochrome c In the ΔGly-141 mutants, the backbone amide of Glu/Asn-142 forms an H-bond to the N5 of the oxidized flavin, which leads to formation of an unstable red anionic semiquinone with a more negative potential than the hydroquinone. The semiquinone of ΔG141/E142N was slightly more stable than that of ΔGly-141, consistent with its crystallographically demonstrated more rigid loop. Nonetheless, both ΔGly-141 red semiquinones were less stable than those of the corresponding loop in cytochrome P450 BM3 and the neuronal NOS mutant (ΔGly-810). Our results indicate that the catalytic activity of cytochrome P450 oxidoreductase is a function of the length, sequence, and flexibility of the 140s loop and illustrate the sophisticated variety of biochemical mechanisms employed in fine-tuning its redox properties and function.

Endothelial nitric oxide synthase oxygenase on lipid nanodiscs: A nano-assembly reflecting native-like function of eNOS.

Endothelial nitric oxide synthase (eNOS) is a membrane-anchored enzyme. To highlight the potential role and effect of membrane phospholipids on the structure and activity of eNOS, we have incorporated the recombinant oxygenase subunit of eNOS into lipid nanodiscs. Two different size distribution modes were detected by multi-angle dynamic light scattering both for empty nanodiscs, and nanodiscs-bound eNOSoxy. The calculated hydrodynamic diameter for mode 1 species was 9.0 nm for empty nanodiscs and 9.8 nm for nanodisc bound eNOSoxy. Spectroscopic Griess assay was used to measure the enzymatic activity. Remarkably, the specific activity of nanodisc-bound eNOSoxy is ∼65% lower than the activity of free enzyme. The data shows that the nano-membrane environment affects the catalytic properties of eNOS heme domain.

Mechanism of inducible nitric-oxide synthase dimerization inhibition by novel pyrimidine imidazoles.

Overproduction of nitric oxide (NO) by inducible nitric-oxide synthase (iNOS) has been etiologically linked to several inflammatory, immunological, and neurodegenerative diseases. As dimerization of NOS is required for its activity, several dimerization inhibitors, including pyrimidine imidazoles, are being evaluated for therapeutic inhibition of iNOS. However, the precise mechanism of their action is still unclear. Here, we examined the mechanism of iNOS inhibition by a pyrimidine imidazole core compound and its derivative (PID), having low cellular toxicity and high affinity for iNOS, using rapid stopped-flow kinetic, gel filtration, and spectrophotometric analysis. PID bound to iNOS heme to generate an irreversible PID-iNOS monomer complex that could not be converted to active dimers by tetrahydrobiopterin (H4B) and l-arginine (Arg). We utilized the iNOS oxygenase domain (iNOSoxy) and two monomeric mutants whose dimerization could be induced (K82AiNOSoxy) or not induced (D92AiNOSoxy) with H4B to elucidate the kinetics of PID binding to the iNOS monomer and dimer. We observed that the apparent PID affinity for the monomer was 11 times higher than the dimer. PID binding rate was also sensitive to H4B and Arg site occupancy. PID could also interact with nascent iNOS monomers in iNOS-synthesizing RAW cells, to prevent their post-translational dimerization, and it also caused irreversible monomerization of active iNOS dimers thereby accomplishing complete physiological inhibition of iNOS. Thus, our study establishes PID as a versatile iNOS inhibitor and therefore a potential in vivo tool for examining the causal role of iNOS in diseases associated with its overexpression as well as therapeutic control of such diseases.

Cost-effectiveness of diagnosis and treatment of early gestational diabetes mellitus: economic evaluation of the TOBOGM study, an international multicenter randomized controlled trial.

Background: A recently undertaken multicenter randomized controlled trial (RCT) "Treatment Of BOoking Gestational diabetes Mellitus" (TOBOGM: 2017-2022) found that the diagnosis and treatment of pregnant women with early gestational diabetes mellitus (GDM) improved pregnancy outcomes. Based on data from the trial, this study aimed to assess the cost-effectiveness of diagnosis and treatment of early GDM (from <20 weeks') among women with risk factors for hyperglycemia in pregnancy compared with usual care (no treatment until 24-28 weeks') from a healthcare perspective. Methods: Participants' healthcare resource utilization data were collected from their self-reported questionnaires and hospital records, and valued using the unit costs obtained from standard Australian national sources. Costs were reported in US dollars ($) using the purchasing power parity (PPP) estimates to facilitate comparison of costs across countries. Intention-to-treat (ITT) principle was followed. Missing cost data were replaced using multiple imputations. Bootstrapping method was used to estimate the uncertainty around mean cost difference and cost-effectiveness results. Bootstrapped cost-effect pairs were used to plot the cost-effectiveness (CE) plane and cost-effectiveness acceptability curve (CEAC). Findings: Diagnosis and treatment of early GDM was more effective and tended to be less costly, i.e., dominant (cost-saving) [-5.6% composite adverse pregnancy outcome (95% CI: -10.1%, -1.2%), -$1373 (95% CI: -$3,749, $642)] compared with usual care. Our findings were confirmed by both the CE plane (88% of the bootstrapped cost-effect pairs fall in the south-west quadrant), and CEAC (the probability of the intervention being cost-effective ranged from 84% at a willingness-to-pay (WTP) threshold value of $10,000-99% at a WTP threshold value of $100,000 per composite adverse pregnancy outcome prevented). Sub-group analyses demonstrated that diagnosis and treatment of early GDM among women in the higher glycemic range (fasting blood glucose 95-109 mg/dl [5.3-6.0 mmol/L], 1-h blood glucose ≥191 mg/dl [10.6 mmol/L] and/or 2-h blood glucose 162-199 mg/dl [9.0-11.0 mmol/L]) was more effective and less costly (dominant) [-7.8% composite adverse pregnancy outcome (95% CI: -14.6%, -0.9%), -$2795 (95% CI: -$6,638, -$533)]; the intervention was more effective and tended to be less costly [-8.9% composite adverse pregnancy outcome (95% CI: -15.1%, -2.6%), -$5548 (95% CI: -$16,740, $1547)] among women diagnosed before 14 weeks' gestation as well. Interpretation: Our findings highlight the potential health and economic benefits from the diagnosis and treatment of early GDM among women with risk factors for hyperglycemia in pregnancy and supports its implementation. Long-term follow-up studies are recommended as a key future area of research to assess the potential long-term health benefits and economic consequences of the intervention. Funding: National Health and Medical Research Council (grants 1104231 and 2009326), Region O¨rebro Research Committee (grants Dnr OLL-970566 and OLL-942177), Medical Scientific Fund of the Mayor of Vienna (project 15,205 and project 23,026), South Western Sydney Local Health District Academic Unit (grant 2016), and Western Sydney University Ainsworth Trust Grant (2019).

Factors associated with Pharmaceutical Benefits Advisory Committee decisions for listing medicines for diabetes and its associated complications.

Objective To retrospectively analyse the key factors associated with listing decisions by the Pharmaceutical Benefits Advisory Committee (PBAC) for medicines for diabetes and its complications on the Pharmaceutical Benefits Scheme. Methods The clinical and economic evidence were retrieved from public summary documents (PSD) of all major submissions between July 2005 and March 2020. A multivariate binary logit regression analysis was conducted to assess the relationship between the categorical explanatory variables and PBAC recommendations. Results We identified a total of 211 PSD of which 118 (56%) were recommended for listing. Clinical and economic uncertainty were significantly and inversely associated with the PBAC recommendation. Submissions with high clinical and economic uncertainty were less likely to be recommended. Conclusion Our findings will enhance the understanding of medical professionals, pharmaceutical companies, and other stakeholders about the rationale of PBAC reimbursement decisions for these medicines and assist prospective applicant sponsor companies in preparing their submissions.

Specific O-GlcNAc modification at Ser-615 modulates eNOS function.

Idiopathic pulmonary arterial hypertension (IPAH) is a progressive and devastating disease characterized by vascular smooth muscle and endothelial cell proliferation leading to a narrowing of the vessels in the lung. The increased resistance in the lung and the higher pressures generated result in right heart failure. Nitric Oxide (NO) deficiency is considered a hallmark of IPAH and altered function of endothelial nitric oxide synthase (eNOS), decreases NO production. We recently demonstrated that glucose dysregulation results in augmented protein serine/threonine hydroxyl-linked N-Acetyl-glucosamine (O-GlcNAc) modification in IPAH. In diabetes, dysregulated glucose metabolism has been shown to regulate eNOS function through inhibition of Ser-1177 phosphorylation. However, the link between O-GlcNAc and eNOS function remains unknown. Here we show that increased protein O-GlcNAc occurs on eNOS in PAH and Ser-615 appears to be a novel site of O-GlcNAc modification resulting in reduced eNOS dimerization. Functional characterization of Ser-615 demonstrated the importance of this residue on the regulation of eNOS activity through control of Ser-1177 phosphorylation. Here we demonstrate a previously unidentified regulatory mechanism of eNOS whereby the O-GlcNAc modification of Ser-615 results in reduced eNOS activity and endothelial dysfunction under conditions of glucose dysregulation.

Pre-steady state kinetics of ATP hydrolysis by Na,K-ATPase.

Fast reaction kinetics of ATP hydrolysis by Na,K-ATPase has been investigated by following absorption pattern of pH sensitive dye in stopped flow spectrophotometer. Distinct pre-steady state phase signal could be recorded with an initial decrease in acidity followed by increase in acidity. Average half time for H(+) absorption and peak alkalinity was, respectively, 30 ms and 60 ms. Under optimal Na(+) (120 mM) and K(+) (30 mM) concentrations, magnitude of both H(+) absorption and H(+) release are found to be about 1.0 H(+)/ATPase molecule. H(+) absorption and release decreased with decrease in Na(+) concentration, H(+) release was more affected. Both H(+) absorption and H(+) release are found to be independent of K(+) concentration in the pre-steady state phase. No H(+) absorption or release was observed following mixing of either ADP, Na(+) or K(+) alone with ATPase. Effect of delayed mixing of Na(+) or K(+) on two phases of pre-steady state cycle indicates that ATP hydrolytic cycle starts without K(+) ions if optimal Na(+) is present. ATP hydrolytic cycle does not start in the absence of Na(+) ions. Results obtained have been interpreted in terms of an extended kinetic scheme for Na,K-ATPase.

A review of the therapeutic effects of using miswak (Salvadora Persica) on oral health.

Miswak is a traditional chewing stick prepared from the roots, twigs, and stem of Salvadora persica and has been used as a natural method for tooth cleaning in many parts of the world for thousands of years. A number of scientific studies have demonstrated that the miswak (Salvadora persica) possesses antibacterial, anti-fungal, anti-viral, anti-cariogenic, and anti-plaque properties. Several studies have also claimed that miswak has anti-oxidant, analgesic, and anti-inflammatory effects. The use of a miswak has an immediate effect on the composition of saliva. Several clinical studies have confirmed that the mechanical and chemical cleansing efficacy of miswak chewing sticks are equal and at times greater than that of the toothbrush. The present article provides a review of the various therapeutic effects of Salvadora persica on oral health, which will help to elucidate the significance and importance of this indigenous oral hygiene tool.

Distinct conformational behaviors of four mammalian dual-flavin reductases (cytochrome P450 reductase, methionine synthase reductase, neuronal nitric oxide synthase, endothelial nitric oxide synthase) determine their unique catalytic profiles.

Multidomain enzymes often rely on large conformational motions to function. However, the conformational setpoints, rates of domain motions and relationships between these parameters and catalytic activity are not well understood. To address this, we determined and compared the conformational setpoints and the rates of conformational switching between closed unreactive and open reactive states in four mammalian diflavin NADPH oxidoreductases that catalyze important biological electron transfer reactions: cytochrome P450 reductase, methionine synthase reductase and endothelial and neuronal nitric oxide synthase. We used stopped-flow spectroscopy, single turnover methods and a kinetic model that relates electron flux through each enzyme to its conformational setpoint and its rates of conformational switching. The results show that the four flavoproteins, when fully-reduced, have a broad range of conformational setpoints (from 12% to 72% open state) and also vary 100-fold with respect to their rates of conformational switching between unreactive closed and reactive open states (cytochrome P450 reductase > neuronal nitric oxide synthase > methionine synthase reductase > endothelial nitric oxide synthase). Furthermore, simulations of the kinetic model could explain how each flavoprotein can support its given rate of electron flux (cytochrome c reductase activity) based on its unique conformational setpoint and switching rates. The present study is the first to quantify these conformational parameters among the diflavin enzymes and suggests how the parameters might be manipulated to speed or slow biological electron flux.

A kinetic model linking protein conformational motions, interflavin electron transfer and electron flux through a dual-flavin enzyme-simulating the reductase activity of the endothelial and neuronal nitric oxide synthase flavoprotein domains.

NADPH-dependent dual-flavin enzymes provide electrons in many redox reactions, although the mechanism responsible for regulating their electron flux remains unclear. We recently proposed a four-state kinetic model that links the electron flux through a dual-flavin enzyme to its rates of interflavin electron transfer and FMN domain conformational motion [Stuehr DJ et al. (2009) FEBS J276, 3959-3974]. In the present study, we ran computer simulations of the kinetic model to determine whether it could fit the experimentally-determined, pre-steady-state and steady-state traces of electron flux through the neuronal and endothelial NO synthase flavoproteins (reductase domains of neuronal nitric oxide synthase and endothelial nitric oxide synthase, respectively) to cytochrome c. We found that the kinetic model accurately fitted the experimental data. The simulations gave estimates for the ensemble rates of interflavin electron transfer and FMN domain conformational motion in the reductase domains of neuronal nitric oxide synthase and endothelial nitric oxide synthase, provided the minimum rate boundary values, and predicted the concentrations of the four enzyme species that cycle during catalysis. The findings of the present study suggest that the rates of interflavin electron transfer and FMN domain conformational motion are counterbalanced such that both processes may limit electron flux through the enzymes. Such counterbalancing would allow a robust electron flux at the same time as keeping the rates of interflavin electron transfer and FMN domain conformational motion set at relatively slow levels.

Structural and mechanistic aspects of flavoproteins: electron transfer through the nitric oxide synthase flavoprotein domain.

Nitric oxide synthases belong to a family of dual-flavin enzymes that transfer electrons from NAD(P)H to a variety of heme protein acceptors. During catalysis, their FMN subdomain plays a central role by acting as both an electron acceptor (receiving electrons from FAD) and an electron donor, and is thought to undergo large conformational movements and engage in two distinct protein-protein interactions in the process. This minireview summarizes what we know about the many factors regulating nitric oxide synthase flavoprotein domain function, primarily from the viewpoint of how they impact electron input/output and conformational behaviors of the FMN subdomain.