Alterations in CD39/CD73 axis of T cells associated with COVID-19 severity.

Purinergic signaling modulates immune function and is involved in the immunopathogenesis of several viral infections. This study aimed to investigate alterations in purinergic pathways in coronavirus disease 2019 (COVID-19) patients. Mild and severe COVID-19 patients had lower extracellular adenosine triphosphate and adenosine levels, and higher cytokines than healthy controls. Mild COVID-19 patients presented lower frequencies of CD4+ CD25+ CD39+ (activated/memory regulatory T cell [mTreg]) and increased frequencies of high-differentiated (CD27- CD28- ) CD8+ T cells compared with healthy controls. Severe COVID-19 patients also showed higher frequencies of CD4+ CD39+ , CD4+ CD25- CD39+ (memory T effector cell), and high-differentiated CD8+ T cells (CD27- CD28- ), and diminished frequencies of CD4+ CD73+ , CD4+ CD25+ CD39+ mTreg cell, CD8+ CD73+ , and low-differentiated CD8+ T cells (CD27+ CD28+ ) in the blood in relation to mild COVID-19 patients and controls. Moreover, severe COVID-19 patients presented higher expression of PD-1 on low-differentiated CD8+ T cells. Both severe and mild COVID-19 patients presented higher frequencies of CD4+ Annexin-V+ and CD8+ Annexin-V+ T cells, indicating increased T-cell apoptosis. Plasma samples collected from severe COVID-19 patients were able to decrease the expression of CD73 on CD4+ and CD8+ T cells of a healthy donor. Interestingly, the in vitro incubation of peripheral blood mononuclear cell from severe COVID-19 patients with adenosine reduced the nuclear factor-κB activation in T cells and monocytes. Together, these data add new knowledge to the COVID-19 immunopathology through purinergic regulation.

Population pharmacokinetic modeling of GS-441524, the active metabolite of remdesivir, in Japanese COVID-19 patients with renal dysfunction.

Remdesivir, a prodrug of the nucleoside analog GS-441524, plays a key role in the treatment of coronavirus disease 2019 (COVID-19). However, owing to limited information on clinical trials and inexperienced clinical use, there is a lack of pharmacokinetic (PK) data in patients with COVID-19 with special characteristics. In this study, we aimed to measure serum GS-441524 concentrations and develop a population PK (PopPK) model. Remdesivir was administered at a 200 mg loading dose on the first day followed by 100 mg from day 2, based on the package insert, in patients with an estimated glomerular filtration rate (eGFR) greater than or equal to 30 ml/min. In total, 190 concentrations from 37 Japanese patients were used in the analysis. The GS-441524 trough concentrations were significantly higher in the eGFR less than 60 ml/min group than in the eGFR greater than or equal to 60 ml/min group. Extracorporeal membrane oxygenation in four patients hardly affected the total body clearance (CL) and volume of distribution (Vd ) of GS-441524. A one-compartment model described serum GS-441524 concentration data. The CL and Vd of GS-441524 were significantly affected by eGFR readjusted by individual body surface area and age, respectively. Simulations proposed a dose regimen of 200 mg on day 1 followed by 100 mg once every 2 days from day 2 in patients with an eGFR of 30 ml/min or less. In conclusion, we successfully established a PopPK model of GS-441524 using retrospectively obtained serum GS-441524 concentrations in Japanese patients with COVID-19, which would be helpful for optimal individualized therapy of remdesivir.

Metabolite Biomarkers of CKD Progression in Children.

BACKGROUND AND OBJECTIVES: Metabolomics facilitates the discovery of biomarkers and potential therapeutic targets for CKD progression. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We evaluated an untargeted metabolomics quantification of stored plasma samples from 645 Chronic Kidney Disease in Children (CKiD) participants. Metabolites were standardized and logarithmically transformed. Cox proportional hazards regression examined the association between 825 nondrug metabolites and progression to the composite outcome of KRT or 50% reduction of eGFR, adjusting for age, sex, race, body mass index, hypertension, glomerular versus nonglomerular diagnosis, proteinuria, and baseline eGFR. Stratified analyses were performed within subgroups of glomerular/nonglomerular diagnosis and baseline eGFR. RESULTS: Baseline characteristics were 391 (61%) male; median age 12 years; median eGFR 54 ml/min per 1.73 m2; 448 (69%) nonglomerular diagnosis. Over a median follow-up of 4.8 years, 209 (32%) participants developed the composite outcome. Unique association signals were identified in subgroups of baseline eGFR. Among participants with baseline eGFR ≥60 ml/min per 1.73 m2, two-fold higher levels of seven metabolites were significantly associated with higher hazards of KRT/halving of eGFR events: three involved in purine and pyrimidine metabolism (N6-carbamoylthreonyladenosine, hazard ratio, 16; 95% confidence interval, 4 to 60; 5,6-dihydrouridine, hazard ratio, 17; 95% confidence interval, 5 to 55; pseudouridine, hazard ratio, 39; 95% confidence interval, 8 to 200); two amino acids, C-glycosyltryptophan, hazard ratio, 24; 95% confidence interval 6 to 95 and lanthionine, hazard ratio, 3; 95% confidence interval, 2 to 5; the tricarboxylic acid cycle intermediate 2-methylcitrate/homocitrate, hazard ratio, 4; 95% confidence interval, 2 to 7; and gulonate, hazard ratio, 10; 95% confidence interval, 3 to 29. Among those with baseline eGFR <60 ml/min per 1.73 m2, a higher level of tetrahydrocortisol sulfate was associated with lower risk of progression (hazard ratio, 0.8; 95% confidence interval, 0.7 to 0.9). CONCLUSIONS: Untargeted plasma metabolomic profiling facilitated discovery of novel metabolite associations with CKD progression in children that were independent of established clinical predictors and highlight the role of select biologic pathways.

Quantitative HPLC-MS/MS determination of Nuc, the active metabolite of remdesivir, and its pharmacokinetics in rat.

Remdesivir is a nucleotide analog prodrug that has received much attention since the outbreak of the COVID-19 pandemic in December 2019. GS-441524 (Nuc) is the active metabolite of remdesivir and plays a pivotal role in the clinical treatment of COVID-19. Here, a robust HPLC-MS/MS method was developed to determine Nuc concentrations in rat plasma samples after a one-step protein precipitation process. Chromatographic separation was accomplished on Waters XBrige C18 column (50 × 2.1 mm, 3.5 µm) under gradient elution conditions. Multiple reaction monitoring transitions in electrospray positive ion mode were m/z 292.2 → 163.2 for Nuc and 237.1 → 194.1 for the internal standard (carbamazepine). The quantitative analysis method was fully validated in line with the United States Food and Drug Administration guidelines. The linearity, accuracy and precision, matrix effect, recovery, and stability results met the requirements of the guidelines. Uncertainty of measurement and incurred sample reanalysis were analyzed to further ensure the robustness and reproducibility of the method. This optimized method was successfully applied in a rat pharmacokinetics study of remdesivir (intravenously administration, 5 mg kg-1). The method can act as a basis for further pharmacokinetic and clinical efficacy investigations in patients with COVID-19. Graphical abstract.

Changed signals of blood adenosine and cytokines are associated with parameters of sleep and/or cognition in the patients with chronic insomnia disorder.

OBJECTIVES: This study aimed to investigate whether plasma levels of adenosine, adenosine deaminase (ADA), and certain cytokines change in patients with chronic insomnia disorder (CID), and if so, whether these alterations are associated with poor sleep quality and cognitive dysfunction. METHODS: Fifty-five CID patients were selected for the study, along with fifty-five healthy controls (HC) matched to the patients according to their basic data. All subjects completed sleep, emotion, and cognition assessments, with some CID patients also completing an overnight polysomnography. The plasma level of adenosine was measured using liquid chromatography-tandem mass spectrometry, while ADA level was quantified using a quantitative sandwich enzyme-linked immunosorbent assay. Levels of cytokines, including IL-1ß, IL-2, IL-4, IL-6, IL-10, IL-12, TNF-α, and IFN-γ, were measured using Luminex liquid chip technology. RESULTS: CID patients had a lower adenosine level, and higher levels of ADA and some of the cytokines (IL-1ß, IL-2, IL-6, IL-10 and TNF-α) compared with controls. In the CID group, plasma concentrations of adenosine were negatively correlated with Pittsburgh Sleep Quality Index scores, while concentrations of IL-1ß, IL-6 and TNF-α were positively correlated with these scores. Concentrations of IL-1ß and TNF-α were negatively correlated with scores on the Chinese-Beijing Version of the Montreal Cognitive Assessment. Moreover, levels of IL-1ß, TNF-α, IL-6, and IL-2 were positively correlated with memory test errors by CID patients after controlling for confounding factors. CONCLUSIONS: The reduced adenosine and elevated cytokine levels of CID patients were associated with the severity of insomnia and/or cognitive dysfunction.

Elevated blood purine levels as a biomarker of seizures and epilepsy.

OBJECTIVE: There is a major unmet need for a molecular biomarker of seizures or epilepsy that lends itself to fast, affordable detection in an easy-to-use point-of-care device. Purines such as adenosine triphosphate and adenosine are potent neuromodulators released during excessive neuronal activity that are also present in biofluids. Their biomarker potential for seizures and epilepsy in peripheral blood has, however, not yet been investigated. The aim of the present study was to determine whether blood purine nucleoside measurements can serve as a biomarker for the recent occurrence of seizures and to support the diagnosis of epilepsy. METHODS: Blood purine concentrations were measured via a point-of-care diagnostic technology based on the summated electrochemical detection of adenosine and adenosine breakdown products (inosine, hypoxanthine, and xanthine; SMARTChip). Measurements of blood purine concentrations were carried out using samples from mice subjected to intra-amygdala kainic acid-induced status epilepticus and in video-electroencephalogram (EEG)-monitored adult patients with epilepsy. RESULTS: In mice, blood purine concentrations were rapidly increased approximately two- to threefold after status epilepticus (2.32 ± .40 µmol·L-1 [control] vs. 8.93 ± 1.03 µmol·L-1 [after status epilepticus]), and levels correlated with seizure burden and postseizure neurodegeneration in the hippocampus. Blood purine concentrations were also elevated in patients with video-EEG-diagnosed epilepsy (2.39 ± .34 µmol·L-1 [control, n = 13] vs. 4.35 ± .38 µmol·L-1 [epilepsy, n = 26]). SIGNIFICANCE: Our data provide proof of concept that the measurement of blood purine concentrations may offer a rapid, low-volume bedside test to support the diagnosis of seizures and epilepsy.

Impact of aging on the effects of intracoronary adenosine, peak hyperemia and its duration during fractional flow reserve assessment.

INTRODUCTION: Functional assessment of coronary stenoses is crucial for determining the correct therapeutic strategy. Age-related modifications in cardiovascular function could alter the functional significance of an intermediate coronary lesion. Therefore, the aim of the present study was to investigate the impact of age on fractional flow reserve (FFR) measurements in patients with intermediate coronary artery disease. METHODS: We included patients undergoing coronary angiography at our Division of Cardiology from June 2008 to February 2019 for elective indication or recent acute coronary syndrome and receiving FFR assessment for an intermediate coronary stenosis (angiographic 40-70% stenoses). FFR measurement was performed by pressure-recording guidewire (Prime Wire; Volcano Imaging System Philips Healthcare, San Diego, California, USA), after induction of hyperemia with intracoronary boluses of adenosine (from 60 to 720 µg, with dose doubling at each step). RESULTS: We included in our study 276 patients, undergoing FFR evaluation on 314 lesions, that were divided according to age (< or ≥70 years). Elderly patients displayed a higher cardiovascular risk profile and received more often specific therapy. We found significantly higher FFR values and lower Delta FFR and time to recovery in patients with age ≥70 years old even with high-dose adenosine. Elderly patients showed a trend in lower percentage of positive FFRs, especially with high-dose (P = 0.09). Overall, any FFR ≤ 0.80 was observed in 33.5% of younger patients and 21.1% of patients ≥70 years (P = 0.02). Results were confirmed after correction for baseline differences [adjusted odds ratio (95% confidence interval) = 0.60 (0.33-1.09), P = 0.08]. CONCLUSION: This is one of the first studies investigating the impact of age on the measurement of FFR with high-dose adenosine. Patients with age >70 years old with intermediate CAD are more likely to have higher FFR values and lower duration of hyperemia after adenosine boluses, as compared with younger patients.

New insights in diagnostics and therapies in syncope: a novel approach to non-cardiac syncope.

This article aims to give advice on how to identify and manage patients with syncope who are at risk of severe outcomes, that is, at risk of trauma, potentially life-threatening episodes or frequent recurrences reducing quality of life. The first step of syncope diagnostic assessment is to identify patients with cardiac syncope, and once established, these patients must receive the adequate mechanism-specific treatment. If cardiac syncope is unlikely, reflex (neurally mediated) syncope and orthostatic hypotension are the most frequent causes of transient loss of consciousness. For these presentations, efficacy of therapy is largely determined by the mechanism of syncope rather than its aetiology or clinical features. The identified mechanism of syncope should be carefully assessed and assigned either to hypotensive or bradycardic phenotype, which will determine the choice of therapy (counteracting hypotension or counteracting bradycardia). The results of recent trials indicate that 'mechanism-specific therapy' is highly effective in preventing recurrences. Established mechanism-specific treatment strategies include withdrawal of hypotensive drugs, applying fludrocortisone and midodrine for the hypotensive phenotype and cardiac pacing in the bradycardic phenotype.

Adaptative mechanism of the equilibrative nucleoside transporter 1 (ENT-1) and blood adenosine levels in elite freedivers.

PURPOSE: Long static or intense dynamic apnoea-like high-altitude exposure is inducing hypoxia. Adenosine is known to participate to the adaptive response to hypoxia leading to the control of heart rate, blood pressure and vasodilation. Extracellular adenosine level is controlled through the equilibrative nucleoside transporter 1 (ENT-1) and the enzyme adenosine deaminase (ADA). The aim of this study was to determine the control of adenosine blood level (ABL) via ENT-1 and ADA during apnoea-induced hypoxia in elite freedivers was similar to high-altitude adaptation. METHODS: Ten freediver champions and ten controls were studied. Biological (e.g. ENT-1, ADA, ABL, PaO2, PaCO2 and pH) and cardiovascular (e.g. heart rate, arterial pressure) parameters were measured at rest and after a submaximal dry static apnoea. RESULTS: In freedivers, ABL was higher than in control participants in basal condition and increased more in response to apnoea. Also, freedivers showed an ADA increased in response to apnoea. Finally, ENT-1 level and function were reduced for the free divers. CONCLUSION: Our results suggest in freedivers the presence of an adaptive mechanism similar to the one observed in human exposed to chronic hypoxia induced by high-altitude environment.

Cilostazol increases adenosine plasma concentration in patients with acute coronary syndrome.

WHAT IS KNOWN AND OBJECTIVE: Cilostazol is a specific and strong inhibitor of phosphodiesterase (PDE) type III which can suppress the platelet aggregation by increasing cyclic adenosine monophosphate (cAMP) levels. The clinical benefit of cilostazol in ACS patients suggested that the drug may have non-platelet-directed properties. Some in vitro and animal studies also indicated that the 'pleiotropic' properties of cilostazol might be related to the interaction with adenosine metabolism. Adenosine is an important regulatory metabolite and an inhibitor of platelet activation. However, no human study has been conducted to determine whether cilostazol could increase the adenosine plasma concentration in vivo. As a result, this study aimed to investigate the impact of cilostazol on adenosine plasma concentration (APC) in acute coronary syndrome (ACS) patients. METHODS: We prospectively analysed 149 ACS patients undergoing percutaneous coronary intervention (PCI) with drug-eluting stents. The included patients were divided into two groups according to the presence (cilostazol group, n = 64) or absence (aspirin group, n = 85) of aspirin intolerance. The inhibition of platelet aggregation (IPA), APC and cAMP concentration was measured. Patient characteristics, medications and 30-day clinical outcomes were examined. RESULTS: Patients receiving cilostazol had a significantly higher adenosine and cAMP plasma concentration than patients receiving aspirin (3.00 ± 0.67 vs 2.56 ± 0.74 mol/L, P < .001; 28.10 ± 14.74 vs 20.48 ± 11.35 pmol/mL, P = .0014). Cilostazol was associated with a higher inhibition rate of ADP induced platelet aggregation than aspirin (63.35 ± 26.71 vs 52.2 ± 28.35, P = .036). The plasma levels of adenosine and cAMP showed a positive correlation with ADP induced platelet aggregation. WHAT IS NEW AND CONCLUSION: Cilostazol increases adenosine concentration compared with aspirin. Its potent antiplatelet effect in ACS patients may be partly mediated by adenosine.

Ticagrelor: a cardiometabolic drug targeting erythrocyte-mediated purinergic signaling?

Cardiometabolic diseases lead to vascular complications, which cause increasing morbidity and mortality worldwide. The underlying mechanisms are multifactorial and complex but may involve altered purinergic signaling that significantly contributes to cardiovascular dysfunction. Ticagrelor is a successful purinergic drug directly targeting ADP-mediated P2Y12R signaling for platelet aggregation and is widely used in patients with acute coronary syndrome. In addition, ticagrelor can target red blood cells (RBCs) to release ATP and inhibit adenosine uptake by RBCs, which subsequently activate purinergic signaling. This involvement in purinergic signaling may allow ticagrelor to mediate pleiotropic effects and contribute to the beneficial cardiovascular outcomes observed in clinical studies. Recent studies have established a novel function of RBCs, which is that RBCs act as disease mediators for the development of cardiovascular complications in type 2 diabetes (T2D). RBC-released ATP is defective in T2D, which has implications for the induction of vascular dysfunction by dysregulating purinergic signaling. Ticagrelor might target RBCs and restore the bioavailability of ATP and adenosine, thereby attenuating cardiovascular complications. The present perspective discusses the pleiotropic effect of ticagrelor, with a focus on the possibility of ticagrelor for the treatment of cardiometabolic complications by targeting RBCs and initiating purinergic activation. A better understanding of the proposed cardiometabolic effects could support novel clinical indications for ticagrelor application.

Performance of Plasma Adenosine as a Biomarker for Predicting Cardiovascular Risk.

Adenosine boasts promising preclinical and clinical data supporting a vital role in modulating vascular homeostasis. Its widespread use as a diagnostic and therapeutic agent have been limited by its short half-life and complex biology, though adenosine-modulators have shown promise in improving vascular healing. Moreover, circulating adenosine has shown promise in predicting cardiovascular (CV) events. We sought to delineate whether circulating plasma adenosine levels predict CV events in patients undergoing invasive assessment for coronary artery disease. Patients undergoing invasive angiography had clinical data prospectively recorded in the Cardiovascular and Percutaneous ClInical TriALs (CAPITAL) revascularization registry and blood samples collected in the CAPITAL Biobank from which adenosine levels were quantified. Tertile-based analysis was used to assess prediction of major adverse cardiovascular events (MACE; composite of death, myocardial infarction, unplanned revascularization, and cerebrovascular accident). Secondary analyses included MACE subgroups, clinical subgroups and adenosine levels. There were 1,815 patients undergoing angiography who had blood collected with adenosine quantified in 1,323. Of those quantified, 51.0% were revascularized and 7.3% experienced MACE in 12 months of follow-up. Tertile-based analysis failed to demonstrate any stratification of MACE rates (log rank, P = 0.83), when comparing low-to-middle (hazard ratio (HR) 1.10, 95% confidence interval (CI) 0.68-1.78, P = 0.70) or low-to-high adenosine tertiles (HR 0.95, 95% CI 0.56-1.57, P = 0.84). In adjusted analysis, adenosine similarly failed to predict MACE. Finally, adenosine did not predict outcomes in patients with acute coronary syndrome nor in those revascularized or treated medically. Plasma adenosine levels do not predict subsequent CV outcomes or aid in patient risk stratification.

Adenosine and Metabotropic Glutamate Receptors Are Present in Blood Serum and Exosomes from SAMP8 Mice: Modulation by Aging and Resveratrol.

Adenosine (ARs) and metabotropic glutamate receptors (mGluRs) are G-protein coupled receptors (GPCRs) that are modulated in the brain of SAMP8 mice, an animal model of Alzheimer's disease (AD). In the present work, it is shown the presence of ARs and mGluRs in blood serum and derived exosomes from SAMP8 mice as well as its possible modulation by aging and resveratrol (RSV) consumption. In blood serum, adenosine A1 and A2A receptors remained unaltered from 5 to 7 months of age. However, an age-related decrease in adenosine level was observed, while 5'-Nucleotidase activity was not modulated. Regarding the glutamatergic system, it was observed a decrease in mGluR5 density and glutamate levels in older mice. In addition, dietary RSV supplementation caused an age-dependent modulation in both adenosinergic and glutamatergic systems. These GPCRs were also found in blood serum-derived exosomes, which might suggest that these receptors could be released into circulation via exosomes. Interestingly, changes elicited by age and RSV supplementation on mGluR5 density, and adenosine and glutamate levels were similar to that detected in whole-brain. Therefore, we might suggest that the quantification of these receptors, and their corresponding endogenous ligands, in blood serum could have predictive value for early diagnosis in combination with other distinctive hallmarks of AD.

Adenosine and Its Receptors: An Expected Tool for the Diagnosis and Treatment of Coronary Artery and Ischemic Heart Diseases.

Adenosine is an endogenous nucleoside which strongly impacts the cardiovascular system. Adenosine is released mostly by endothelial cells and myocytes during ischemia or hypoxia and greatly regulates the cardiovascular system via four specific G-protein-coupled receptors named A1R, A2AR, A2BR, and A3R. Among them, A2 subtypes are strongly expressed in coronary tissues, and their activation increases coronary blood flow via the production of cAMP in smooth muscle cells. A2A receptor modulators are an opportunity for intense research by the pharmaceutical industry to develop new cardiovascular therapies. Most innovative therapies are mediated by the modulation of adenosine release and/or the activation of the A2A receptor subtypes. This review aims to focus on the specific exploration of the adenosine plasma level and its relationship with the A2A receptor, which seems a promising biomarker for a diagnostic and/or a therapeutic tool for the screening and management of coronary artery disease. Finally, a recent class of selective adenosine receptor ligands has emerged, and A2A receptor agonists/antagonists are useful tools to improve the management of patients suffering from coronary artery disease.

A novel serum metabolome score for breast cancer diagnosis.

INTRODUCTION: Early detection of breast cancer is important in diagnosis and treatment, and so in enhancing patient survival and reducing death rates. Because of the low diagnostic sensitivity and specificity of widely used breast cancer biomarkers such as CA15-3, we hypothesised that a panel of new metabolic markers would provide superior sensitivity and specificity for this disease. MATERIAL & METHODS: We recruited 120 women with malignant breast cancer, 47 with benign breast disease and 55 females as a healthy control group. Metabolites 8-hydroxy-2'-deoxyguanosine, 1-methylguanosine, and 1-methyl adenosine were detected and quantified by gas chromatography-mass spectrometry, CA15.3 by ELISA. Cut-off values of individual and combined metabolome with CA15-3 were analysed using the receiver operating characteristics curve (ROCC) to test the efficiency of the candidate metabolome in identifying breast cancer. RESULTS: The overall linear trend of biomarkers across the groups was significant with highest levels in breast cancer (all p < 0.05). Using cut-off values of CA15-3, 8-hydroxy-2'-deoxyguanosine, 1-methylguanosine and 1-methyl adenosine of 30.5 U/l, 15.0 µg/l, 18.5 µg/l and 22.0 µg/l, respectively, diagnostic performance analyses of combined metabolome with CA15-3 gave a ROCC area under the curve of 0.94 (95% CI: 0.91-0.98)(p < 0.01) with good sensitivity (88.8%), specificity (86.8%) and efficiency (90.6%). Unlike CA15.3, the highest levels of each of the metabolite were in the early stage of breast cancer. CONCLUSION: The diagnostic combination test of candidate metabolome with CA15.3 may be a useful tool for the early detection of breast cancer and used as a metabolomics signature in this disease.

Adenosine-imprinted magnetic core-shell polyvinylbutyral microbeads for quantification of adenosine in plasma.

Adenosine is an important molecule in the human body because it participates various biochemical processes, signalling in the physiological processes, and neurological disorders. In the current study, the surface imprinting method was used to prepare adenosine-imprinted magnetic core-shell polyvinylbutyral microbeads. These microbeads were utilized for quantification of adenosine in aqueous solution and control plasma in the range of 1-200 µM. The limit of detection was found to be 1.9 nM, which is quite sensitive compared with to some earlier studies. Fourier transform infrared spectroscopy, scanning electron microscopy, and a Zetasizer (particle size analyzer) were used for characterization of the prepared imprinted microbeads. To determine the efficiency of this method, selectivity experiments were conducted with adenosine-imprinted and non-imprinted magnetic core-shell polyvinylbutyral microbeads and with the competitive nucleosides cytidine, uridine, guanosine, and thymidine. Thermodynamic and kinetic studies were performed to assess adsorption of adenosine onto the adenosine-imprinted magnetic core-shell polyvinylbutyral microbeads from adenosine solution. The efficiency was linked to the specific surface reactivity, polarity and porosity of the imprinted microbeads.

Applicability of Supercritical fluid chromatography-Mass spectrometry to metabolomics. II-Assessment of a comprehensive library of metabolites and evaluation of biological matrices.

In this work, the impact of biological matrices, such as plasma and urine, was evaluated under SFCHRMS in the field of metabolomics. For this purpose, a representative set of 49 metabolites were selected. The assessment of the matrix effects (ME), the impact of biological fluids on the quality of MS/MS spectra and the robustness of the SFCHRMS method were each taken into consideration. The results have highlighted a limited presence of ME in both plasma and urine, with 30% of the metabolites suffering from ME in plasma and 25% in urine, demonstrating a limited sensitivity loss in the presence of matrices. Subsequently, the MS/MS spectra evaluation was performed for further peak annotation. Their analyses have highlighted three different scenarios: 63% of the tested metabolites did not suffer from any interference regardless of the matrix; 21% were negatively impacted in only one matrix and the remaining 16% showed the presence of matrix-belonging compounds interfering in both urine and plasma. Finally, the assessment of retention times stability in the biological samples, has brought into evidence a remarkable robustness of the SFCHRMS method. Average RSD (%) values of retention times for spiked metabolites were equal or below 0.5%, in the two biological fluids over a period of three weeks. In the second part of the work, the evaluation of the Sigma Mass Spectrometry Metabolite Library of Standards containing 597 metabolites, under SFCHRMS conditions was performed. A total detectability of the commercial library up to 66% was reached. Among the families of detected metabolites, large percentages were met for some of them. Highly polar metabolites such as amino acids (87%), nucleosides (85%) and carbohydrates (71%) have demonstrated important success rates, equally for hydrophobic analytes such as steroids (78%) and lipids (71%). On the negative side, very poor performance was found for phosphorylated metabolites, namely phosphate-containing compounds (14%) and nucleotides (31%).

Level of N6-Methyladenosine in Peripheral Blood RNA: A Novel Predictive Biomarker for Gastric Cancer.

BACKGROUND: Dysregulation of N6-methyladenosine (m6A) is associated with various human diseases including cancer. This study aimed to evaluate the level of m6A as a biomarker for gastric cancer (GC) diagnosis. METHODS: Peripheral blood samples were collected from 100 GC patients, 30 benign gastric disease (BGD) patients, and 75 healthy controls (HCs). Levels of m6A in total RNA and expression of m6A-related proteins were analyzed. RESULTS: The m6A levels in peripheral blood RNA were significantly increased in the GC group compared with those in the BGD or HC groups; moreover, levels increased with the progression and metastasis of GC and decreased in GC patients after surgery. The area under the curve (AUC) for m6A in the GC group was 0.929 (95% CI, 0.88-0.96), which is markedly greater than the AUCs for carcinoembryonic antigen (CEA; 0.694) and carbohydrate antigen 199 (CA199; 0.603). The combination of CEA and CA199 with m6A improved the AUC to 0.955 (95% CI, 0.91-0.98). The expressions of m6A demethylases ALKBH5 and FTO were significantly downregulated in the GC group compared with the HC group. Coculture with GC cells increased the m6A of RNA in promyelocytic (HL-60) and monocytic (THP-1) leukemia cells and nontumorigenic human peripheral blood B lymphocyte cells (PENG-EBV). Furthermore, a xenograft model enhanced the m6A in peripheral blood RNA of mice. Accordingly, expressions of ALKBH5 and FTO were decreased both in vitro and in vivo. CONCLUSIONS: Level of m6A in peripheral blood RNA is a promising noninvasive diagnostic biomarker for GC patients.

An in-tube aptamer/gold nanoparticles coated capillary solid-phase microextraction for separation of adenosine in serum and urine samples.

As an endogenous nucleoside, adenosine was significant for the diagnosis and treatment of some diseases, such as schizophrenia. However, due to the complicated matrix interference, it was difficult to monitor trace or ultra-trace adenosine directly in bio-samples. In this contribution, a novel in-tube SPME technique based on aptamer/Au nanoparticles coated open tubular fused-silica capillary was established to separate and enrich adenosine in bio-samples with high affinity. Therefore, a uniform and dense AuNPs layer was coated on the inner surface of the open tubular capillary, and then adenosine aptamer was immobilized on AuNPs with a high capacity of 2.44 µg per 27-cm capillary. As a result, the capillary shown high selectivity to adenosine with a selectivity factor of 14.4 when compared with the scrambled aptamer/AuNPs coated capillary. Also, the extraction amount of adenosine was 2.8-24.8 times higher than those of its structural analogs and contrast, such as guanosine, uridine, cytidine, thymidine, and toluic acid. After the optimization of extraction conditions, the aptamer/AuNPs coated in-tube SPME-HPLC method was developed for the adenosine assay with the linear range of 0.002-0.100 µg mL-1 and the detection limit of 0.45 ng mL-1. Subsequently, the approach was applied for trace adenosine monitoring in human serum and urine samples. It showed a strong performance of reducing matrix interference and improving sensitivity, and the spiking recoveries of 89.9-92.6% and 91.1-94.5% were achieved respectively.

A combination of α-fetoprotein, midkine, thioredoxin and a metabolite for predicting hepatocellular carcinoma.

INTRODUCTION AND OBJECTIVES: The heterogenous nature of hepatocellular carcinoma (HCC) motivated this attempt at developing and validating a model based on combined biomarkers for improving early HCC detection. PATIENTS/MATERIALS AND METHODS: This study examined 196 patients for an estimation study (104 patients with HCC, 52 with liver cirrhosis and 40 with liver fibrosis) and 122 patients for the validation study (80 patients with HCC, 42 with liver cirrhosis). All patients were positive for hepatitis C virus. Four markers were measured: Midkine and thioredoxin using ELISA, 1-methyladenosine and 1-methylguanosine using a gas chromatography-mass spectrometry (GC-MS). The results were compared with alpha-fetoprotein (AFP). The performance of the model was estimated in BCLC, CLIP and Okuda staging systems of HCC. RESULTS: The model yielded high performance with an area under ROC (AUC) of 0.94 for predicting HCC in patients with liver cirrhosis, compared with AUC of 0.69 for AFP. This model had AUCs of 0.93, 0.94 and 0.94 in patients who had only one single nodule, absent macrovascular invasion and tumor size <2cm, respectively, compared with AUCs of 0.71, 0.6 and 0.59 for AFP. The model produced AUCs of 0.91 for BCLC (0-A), 0.92 for CLIP (0-1) and 0.94 for Okuda (stage I) compared with AUCs of 0.56, 0.58 and 0.64 for AFP. No significant difference was found between AUC in the estimation and the validation groups. CONCLUSION: This model may enhance early-stage HCC detection and help to overcome insufficient sensitivity of AFP.