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Dementia is a progressive and debilitating neurological disease that affects millions of people worldwide. Identifying the minimally invasive biomarkers associated with dementia that could provide insights into the disease pathogenesis, improve early diagnosis, and facilitate the development of effective treatments is pressing. Proteomic studies have emerged as a promising approach for identifying the protein biomarkers associated with dementia. This pilot study aimed to investigate the plasma proteome profile and identify a panel of various protein biomarkers for dementia. We used a high-throughput proximity extension immunoassay to quantify 1090 proteins in 122 participants (22 with dementia, 64 with mild cognitive impairment (MCI), and 36 controls with normal cognitive function). Limma-based differential expression analysis reported the dysregulation of 61 proteins in the plasma of those with dementia compared with controls, and machine learning algorithms identified 17 stable diagnostic biomarkers that differentiated individuals with AUC = 0.98 ± 0.02. There was also the dysregulation of 153 plasma proteins in individuals with dementia compared with those with MCI, and machine learning algorithms identified 8 biomarkers that classified dementia from MCI with an AUC of 0.87 ± 0.07. Moreover, multiple proteins selected in both diagnostic panels such as NEFL, IL17D, WNT9A, and PGF were negatively correlated with cognitive performance, with a correlation coefficient (r2) ≤ −0.47. Gene Ontology (GO) and pathway analysis of dementia-associated proteins implicated immune response, vascular injury, and extracellular matrix organization pathways in dementia pathogenesis. In conclusion, the combination of high-throughput proteomics and machine learning enabled us to identify a blood-based protein signature capable of potentially differentiating dementia from MCI and cognitively normal controls. Further research is required to validate these biomarkers and investigate the potential underlying mechanisms for the development of dementia.

Glycation, oxidation, nitration, and crosslinking of proteins are implicated in the pathogenic mechanisms of type 2 diabetes, cardiovascular disease, and chronic kidney disease. Related modified amino acids formed by proteolysis are excreted in urine. We quantified urinary levels of these metabolites and branched-chain amino acids (BCAAs) in healthy subjects and assessed changes in early-stage decline in metabolic, vascular, and renal health and explored their diagnostic utility for a noninvasive health screen. We recruited 200 human subjects with early-stage health decline and healthy controls. Urinary amino acid metabolites were determined by stable isotopic dilution analysis liquid chromatography-tandem mass spectrometry. Machine learning was applied to optimise and validate algorithms to discriminate between study groups for potential diagnostic utility. Urinary analyte changes were as follows: impaired metabolic health—increased Nε-carboxymethyl-lysine, glucosepane, glutamic semialdehyde, and pyrraline; impaired vascular health—increased glucosepane; and impaired renal health—increased BCAAs and decreased Nε-(γ-glutamyl)lysine. Algorithms combining subject age, BMI, and BCAAs discriminated between healthy controls and impaired metabolic, vascular, and renal health study groups with accuracy of 84%, 72%, and 90%, respectively. In 2-step analysis, algorithms combining subject age, BMI, and urinary Nε-fructosyl-lysine and valine discriminated between healthy controls and impaired health (any type), accuracy of 78%, and then between types of health impairment with accuracy of 69%-78% (cf. random selection 33%). From likelihood ratios, this provided small, moderate, and conclusive evidence of early-stage cardiovascular, metabolic, and renal disease with diagnostic odds ratios of 6 – 7, 26 – 28, and 34 – 79, respectively. We conclude that measurement of urinary glycated, oxidized, crosslinked, and branched-chain amino acids provides the basis for a noninvasive health screen for early-stage health decline in metabolic, vascular, and renal health. Other information Published in: Oxidative Medicine and Cellular Longevity License: http://creativecommons.org/licenses/by/4.0 See article on publisher's website: http://dx.doi.org/10.1155/2019/4851323

Mice with ectopic expression of uncoupling protein-1 (UCP1) in skeletal muscle exhibit a healthy aging phenotype with increased longevity and resistance to impaired metabolic health. This may be achieved by decreasing protein glycation by the reactive metabolite, methylglyoxal (MG). We investigated protein glycation and oxidative damage in skeletal muscle of mice with UCP1 expression under control of the human skeletal actin promoter (HSA-mUCP1) at age 12 weeks (young) and 70 weeks (aged). We found both young and aged HSA-mUCP1 mice had decreased advanced glycation endproducts (AGEs) formed from MG, lysine-derived N

Accumulation of advanced glycation endproducts (AGEs) is linked to decline in renal function, particularly in patients with diabetes. Major forms of AGEs in serum are protein-bound AGEs and AGE free adducts. In this study, we assessed levels of AGEs in subjects with and without diabetes, with normal renal function and stages 2 to 4 chronic kidney disease (CKD), to identify which AGE has the greatest progressive change with decline in renal function and change in diabetes. We performed a cross-sectional study of patients with stages 2–4 CKD, with and without diabetes, and healthy controls (n = 135). Nine protein-bound and free adduct AGEs were quantified in serum. Most protein-bound AGEs increased moderately through stages 2–4 CKD whereas AGE free adducts increased markedly. Methylglyoxal-derived hydroimidazolone MG-H1 free adduct was the AGE most responsive to CKD status, increasing 8-fold and 30-fold in stage 4 CKD in patients without and with diabetes, respectively. MG-H1 Glomerular filtration flux was increased 5-fold in diabetes, likely reflecting increased methylglyoxal glycation status. We conclude that serum MG-H1 free adduct concentration was strongly related to stage of CKD and increased in diabetes status. Serum MG-H1 free adduct is a candidate AGE risk marker of non-diabetic and diabetic CKD.

There is considerable interest in dietary and other approaches to maintaining blood glucose concentrations within the normal range and minimizing exposure to postprandial hyperglycemic excursions. The accepted marker to evaluate the sustained maintenance of normal blood glucose concentrations is glycated hemoglobin A1c (HbA1c). However, although this is used in clinical practice to monitor glycemic control in patients with diabetes, it has a number of drawbacks as a marker of efficacy of dietary interventions that might beneficially affect glycemic control in people without diabetes. Other markers that reflect shorter-term glycemic exposures have been studied and proposed, but consensus on the use and relevance of these markers is lacking. We have carried out a systematic search for studies that have tested the responsiveness of 6 possible alternatives to HbA1c as markers of sustained variation in glycemic exposures and thus their potential applicability for use in dietary intervention trials in subjects without diabetes: 1,5-anhydroglucitol (1,5-AG), dicarbonyl stress, fructosamine, glycated albumin (GA), advanced glycated end products (AGEs), and metabolomic profiles. The results suggest that GA may be the most promising for this purpose, but values may be confounded by effects of fat mass. 1,5-AG and fructosamine are probably not sensitive enough to the range of variation in glycemic exposures observed in healthy individuals. Use of measures based on dicarbonyls, AGEs, or metabolomic profiles would require further research into possible specific molecular species of interest. At present, none of the markers considered here is sufficiently validated and sensitive for routine use in substantiating the effects of sustained variation in dietary glycemic exposures in people without diabetes.

Age-related macular degeneration (AMD) is a major blinding disease, affecting over 14% of the elderly. Risk for AMD is related to age, diet, environment, and genetics. Dietary modulation of AMD risk is a promising treatment modality, but requires appropriate animal models to demonstrate advantages of diet. Mice lacking the antioxidant transcription factor Nrf2 (Nfe2l2) develop age-related retinopathy relevant to human AMD. Here we evaluated the effect of consuming high glycemic (HG) or low glycemic (LG) diets until 18-months of age on development of features relevant to AMD in Nrf2-null mice. Nrf2-null mice that consumed HG diets developed atrophic AMD, characterized by photoreceptor degeneration, retinal pigment epithelium (RPE) atrophy and pigmentary abnormalities, basal laminar deposits, and loss of the choriocapillaris. In contrast, Nrf2-null-mice that consumed LG diets did not develop retinal disease phenotypes. Consumption of HG diets was associated with accumulation of advanced glycation end-products in the RPE and systemically, whereas consumption of the LG diet was associated with increased levels of anti-glycative and anti-oxidative detoxification machinery. Together our data indicate that the Nrf2-null HG mouse is a good model for atrophic AMD studies and that the LG diet can activate protective pathways to prevent AMD, even in a genetically predisposed animal.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) provides a high sensitivity, high specificity multiplexed method for concurrent detection of adducts formed by protein glycation, oxidation and nitration, also called AGEomics. Combined with stable isotopic dilution analysis, it provides for robust quantitation of protein glycation, oxidation and nitration adduct analytes. It is the reference method for such measurements. LC-MS/MS has been used to measure glycated, oxidized and nitrated amino acids – also called glycation, oxidation and nitration free adducts, with a concurrent quantitation of the amino acid metabolome in physiological fluids. Similar adduct residues in proteins may be quantitated with prior exhaustive enzymatic hydrolysis. It has also been applied to quantitation of other post-translation modifications, such as citrullination and formation of Nε-(γ-glutamyl)lysine crosslink by transglutaminases. Application to cellular and extracellular proteins gives estimates of the steady-state levels of protein modification by glycation, oxidation and nitration, and measurement of the accumulation of glycation, oxidation and nitration adducts in cell culture medium and urinary excretion gives an indication of flux of adduct formation. Measurement of glycation, oxidation and nitration free adducts in plasma and urine provides for estimates of renal clearance of free adducts. Diagnostic potential in clinical studies has been enhanced by the combination of estimates of multiple adducts in optimized diagnostic algorithms by machine learning. Recent applications have been in early-stage detection of metabolic, vascular and renal disease, and arthritis, metabolic control and risk of developing vascular complication in diabetes, and a blood test for autism.

Transient ischemic attack (TIA) refers to a momentary neurologic deficit caused by focal cerebral, spinal or retinal ischemic insult. TIA is associated with a high risk of impending acute ischemic stroke (AIS), a neurologic dysfunction characterized by focal cerebral, spinal or retinal infarction. Understanding the differences in molecular pathways in AIS and TIA has merit for deciphering the underlying cause for neuronal deficits with long-term effects and high risks of morbidity and mortality. In this study, we performed comprehensive investigations into the circulating microRNA (miRNA) profiles of AIS (n = 191) and TIA (n = 61) patients. We performed RNA-Seq on serum samples collected within 24 hrs of clinical diagnosis and randomly divided the study populations into discovery and validation cohorts. We identified a panel of 11 differentially regulated miRNAs at FDR < 0.05. Hsa-miR-548c-5p, -20a-5p, -18a-5p, -484, -652-3p, -486-3p, -24-3p, -181a-5p and -222-3p were upregulated, while hsa-miR-500a-3p and -206 were downregulated in AIS patients compared to TIA patients. We also probed the previously validated gene targets of our identified miRNA panel to highlight the molecular pathways affected in AIS. Moreover, we developed a multivariate classifier with potential utilization as a discriminative biomarker for AIS and TIA patients. The underlying molecular pathways in AIS compared to TIA may be explored further in functional studies for therapeutic targeting in clinical translation.

Background and aims: Diabetic kidney disease occurs in ca. 40% patients with diabetes. Approximately 1 in 5 patients with type 1 diabetes mellitus (T1DM) and 1 in 3 patients with type 2 diabetes mellitus (T2DM) develop early decline in renal function (EDRF), requiring renal dialysis after 5 - 20 years. Currently, at the time of normoalbuminuria or new onset microalbuminuria (incipient diabetic nephropathy), it is uncertain which patients are at risk of EDRF. With Joslin Kidney Study investigators, we found patients with T1DM who later developed EDRF (Decliners) have higher fractional excretion (FE) of 6 glycated amino acids - fructosyl-lysine and 5 advanced glycation endproducts (AGEs), compared to patients with stable renal function (Non-decliners). However, FE of any single glycated amino acid could not classify Decliners or Non-decliners. The aim of this study was to apply artificial intelligence machine learning to develop diagnostic algorithms to classify Decliners and Non-decliners by optimum combination of levels of glycated and oxidized amino acids in plasma and urine, related FEs and conventional clinical chemistry variables. Materials and methods: Patients with T1DM with stable renal function (n = 63) and EDRF (n = 22) were recruited for this study. Data on levels of 14 glycated and oxidized amino acids in plasma, urine, related FEs, glycated hemoglobin A1C, log(urinary albumin creatinine ratio, ACR), age, gender and duration of diabetes at the time of new onset microalbuminuria were included as features in algorithm development. Algorithms were trained and tested on 90%/10% data split, repeated 1000 times, using the Extreme Gradient Boosting method. Results: The algorithm gave an optimal classification of Decliners and Non-decliners. Optimum with features: A1C, log[ACR], FE(Nꞷ-carboxymethylarginine, CMA), FE(glyoxal-derived hydroimidazolone, G-H1) and plasma concentration of Nε-carboxymethyl-lysine (CML) free adduct; For The diagnostic performance for risk prediction of future EDRF was (mean ± SD): sensitivity 74 ± 9%, specificity 91 ± 45 and accuracy 87 ± 4%. The positive likelihood ratio LR+ was 11.0, indicating that this method gives strong, often conclusive evidence of future EDRF in patients with T1DM. In contrast, algorithms with A1C and logACR only as features gave LR+ 2.6, providing small evidence of risk of future EDRF. Conclusion: With conclude that FEs of glycated amino acids are novel risk predictors of EDRF, likely linked to reporting of early-decline of cationic amino acid transporter function in the renal tubular epithelium. Genetic polymorphism of these amino acid transporters has been linked to rapid decline in renal function in genome-wide association studies. Measurement of only 3 glycated amino acids, CMA, G-H1 and CML, produced an algorithm with optimum risk prediction of EDRF. With further validation, including in patients with T2DM and with chronic kidney disease without diabetes, this method may markedly improve clinical risk prediction of EDRF.

Background and aims: In 2020 a global pandemic was declared caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2). The pandemic is still ongoing and continues to cause considerable mortality and morbidity world-wide and new variants of the virus are emerging. Rapid development and rollout of vaccines for SARS-CoV-2 is in progress to counter the pandemic but has been tempered by the emergence of new SARS-CoV-2 variants, many of which exhibit reduced vaccine effectiveness. To date there is no approved antiviral treatment for coronavirus disease 2019 (COVID-19). Several studies have shown that Manuka honey has virucidal/antiviral effect. Methylglyoxal (MG), a bioactive component in Manuka honey, has antiviral activity in vitro. MG may modify arginine residues in the functional domains of viral spike and nucleocapsid proteins, resulting in loss of charge, protein misfolding and inactivation. The aim of this study was to characterize the antiviral activity of Manuka honey against SARS-CoV-2 in vitro Materials and methods: Wild-type SARS-CoV-2 with titers of multiplicities of infection (MOI) 0.1 and 0.05 were incubated with 2-fold serial dilutions of 250+ Manuka honey (equivalent to 250 to 31 µM) in infection medium (Dulbecco's Modified Eagle Medium + 2% fetal bovine serum + 100 units/ml penicillin + 100 µg/ml streptomycin) for 3 h. Manuka honey treated and untreated control SARS-CoV-2 was incubated with confluent cultures of Vero cells in vitro for 1 h, cultures washed with phosphate-buffered saline and incubated in fresh infection medium at 37°C for 4 - 5 days until 70% of virus control cells displayed cytopathic effect. We also studied the effect of scavenging MG in Manuka Honey with aminoguanidine (AG; 500 µM) on virucidal activity. The antiviral activity of MG was judged by median tissue culture infectious dose (TCID50) assays. Data analysis was by logistic regression. TCID50 (mean ± SD) was deduced by interpolation. Results: Diluted Manuka honey inhibited SARS-CoV-2 replication in Vero cells. SARS-CoV-2 was incubated in diluted Manuka honey in medium at 37°C for 3 h before adding to Vero cells. Manuka honey dilutions down to 125 µM MG equivalents completely inhibited cytopathic effect of SARS-CoV-2 whereas 31.25 µM and 62.5 µM MG equivalents had limited effect. Logistic regression and interpolation of the cytopathic effect indicated that the TCID50 = 72 ± 2 µM MG equivalents for MOI of 0.1. Prior scavenging of MG by addition of AG resulted in virus replication levels equivalent to those seen in the virus control without AG. Conclusion: Manuka honey has antiviral activity against SARS-CoV-2 when incubated with the virus in cell-free media at no greater than ca. 40-fold dilutions of 250+ grade. Anti-viral activity was inhibited by AG, consistent with the anti-viral effect being mediated by MG. Manuka honey dilutions in MG equivalents had similar antiviral effect compared to authentic MG, also consistent with MG content of Manuka honey mediating the antiviral effect. Whilst Manuka honey may inactivate SARS-CoV-2 in cell-free culture medium, its antiviral activity in vivo for other than topical application may be limited because of the rapid metabolism of MG by the glyoxalase system and limited bioavailability of oral MG.

Autism spectrum disorders are a group of neuropsychiatric conditions of increasing prevalence. They are initially detected in early development of children. Diagnosis is currently made on the basis of clinical behaviour and cognition. Improvements in accuracy, timeliness and access to diagnosis to help manage the condition is high on the agenda of the autistic communities. A blood test may help for early-stage detection of autism spectrum disorders to focus support where required — particularly when symptoms are most challenging. This article discusses briefly the scientific basis of diagnosis of autism spectrum disorders and recent emergence of candidate blood tests for autism. We conclude that further validation and improvements in understanding of autism spectrum disorders are required to provide the scientific basis and classifier characteristics for accurate and reliable diagnosis by clinical chemistry blood test.

The dietary supplement, trans-resveratrol and hesperetin combination (tRES-HESP), induces expression of glyoxalase 1, countering the accumulation of reactive dicarbonyl glycating agent, methylglyoxal (MG), in overweight and obese subjects. tRES-HESP produced reversal of insulin resistance, improving dysglycemia and low-grade inflammation in a randomized, double-blind, placebo-controlled crossover study. Herein, we report further analysis of study variables. MG metabolism-related variables correlated with BMI, dysglycemia, vascular inflammation, blood pressure, and dyslipidemia. With tRES-HESP treatment, plasma MG correlated negatively with endothelial independent arterial dilatation (r = −0.48, p &lt, 0.05) and negatively with peripheral blood mononuclear cell (PBMC) quinone reductase activity (r = −0.68, p &lt, 0.05)—a marker of the activation status of transcription factor Nrf2. For change from baseline of PBMC gene expression with tRES-HESP treatment, Glo1 expression correlated negatively with change in the oral glucose tolerance test area-under-the-curve plasma glucose (ΔAUGg) (r = −0.56, p &lt, 0.05) and thioredoxin interacting protein (TXNIP) correlated positively with ΔAUGg (r = 0.59, p &lt, 0.05). Tumor necrosis factor-α (TNFα) correlated positively with change in fasting plasma glucose (r = 0.70, p &lt, 0.001) and negatively with change in insulin sensitivity (r = −0.68, p &lt, 0.01). These correlations were not present with placebo. tRES-HESP decreased low-grade inflammation, characterized by decreased expression of CCL2, COX-2, IL-8, and RAGE. Changes in CCL2, IL-8, and RAGE were intercorrelated and all correlated positively with changes in MLXIP, MAFF, MAFG, NCF1, and FTH1, and negatively with changes in HMOX1 and TKT, changes in IL-8 also correlated positively with change in COX-2. Total urinary excretion of tRES and HESP metabolites were strongly correlated. These findings suggest tRES-HESP counters MG accumulation and protein glycation, decreasing activation of the unfolded protein response and expression of TXNIP and TNFα, producing reversal of insulin resistance. tRES-HESP is suitable for further evaluation for treatment of insulin resistance and related disorders.

Trans-Resveratrol and hesperetin combination (tRES-HESP) in randomized, double-blind, placebo-controlled crossover study in overweight and obese subjects corrected insulin resistance; healthy aging through functional food study (HATFF, Clinicaltrials.gov identifier NCT02095873). tRES-HESP is an optimized supplement for induction of expression of glyoxalase 1 (Glo1) via activation of transcription factor Nrf2. Increased Glo1 expression decreases reactive metabolite, methylglyoxal (MG), contributing to insulin resistance through glycation-linked unfolded protein formation and activation of the unfolded protein response (UPR). Herein, we report further analysis of study variables and follow-up reverse translational studies. With tRES-HESP treatment, plasma MG correlated negatively with peripheral blood mononuclear cell (PBMC) quinone reductase activity - a marker of Nrf2 activation (r = - 0.68, P Disclosure M. Xue: None. M. Weickert: None. N. Rabbani: None. P. Thornalley: None. Funding Qatar Foundation; Qatar University

Diabetic kidney disease occurs in ca. 40% patients with diabetes. Approximately 1 in 5 patients with type 1 diabetes mellitus (T1DM) develop early decline in renal function (EDRF), requiring renal dialysis after 5 - 20 years. Currently, it is uncertain which patients are at high risk of EDRF. With Joslin Kidney Study investigators, we found patients with T1DM with and without microalbuminuria who later develop EDRF (Decliners) have higher fractional excretion (FE) of 6 glycated amino acids - fructosyl-lysine and 5 advanced glycation endproducts (AGEs), compared to patients with stable renal function (Non-decliners) (Perkins et al., Sci Rep 10, 12709, 2020). No individual FE could classify patients. In this study, we applied artificial intelligence machine learning to develop diagnostic algorithms to classify Decliners and Non-decliners, exploring A1C, log(ACR), 14 glycated and oxidized amino acids in plasma, urine, related FEs and other features. Data from patients with T1DM with stable renal function (n = 52) and EDRF (n = 33) were available. Algorithms were trained and tested on 90%/10% data split, repeated 1000 times, using Extreme Gradient Boosting. Optimum classification required measurement of 3 AGEs: Nꞷ-carboxymethylarginine (CMA) and glyoxal-derived hydroimidazolone (G-H1) in plasma and urine, and N-carboxymethyl-lysine (CML) in plasma; measured in 15 min by liquid chromatography-tandem mass spectrometry. Optimum algorithm features were: A1C, log[ACR], FECMA, FEG-H1 and plasma CML free adduct. The diagnostic performance for risk prediction of future EDRF was (mean ± SD): sensitivity 0.74 ± 0.09, specificity 0.91 ± 0.04 and accuracy 87 ± 4%. The positive likelihood ratio LR+ of 11.0 indicates that this method gives strong, often conclusive evidence of future EDRF in patients with T1DM. With further validation, including in patients with type 2 diabetes mellitus, this method may markedly improve risk prediction of EDRF. Disclosure P. Thornalley: None. A. De la fuente: None. N. Rabbani: None. Funding Qatar Foundation; Qatar University

Protein glycation provides a biomarker in widespread clinical use, glycated hemoglobin HbA1c (A1C). It is a biomarker for diagnosis of diabetes and prediabetes and of medium-term glycemic control in patients with established diabetes. A1C is an early-stage glycation adduct of hemoglobin with glucose; a fructosamine derivative. Glucose is an amino group-directed glycating agent, modifying N-terminal and lysine sidechain amino groups. A similar fructosamine derivative of serum albumin, glycated albumin (GA), finds use as a biomarker of glycemic control, particularly where there is interference in use of A1C. Later stage adducts, advanced glycation endproducts (AGEs), are formed by the degradation of fructosamines and by the reaction of reactive dicarbonyl metabolites, such as methylglyoxal. Dicarbonyls are arginine-directed glycating agents forming mainly hydroimidazolone AGEs. Glucosepane and pentosidine, an intense fluorophore, are AGE covalent crosslinks. Cellular proteolysis of glycated proteins forms glycated amino acids, which are released into plasma and excreted in urine. Development of diagnostic algorithms by artificial intelligence machine learning is enhancing the applications of glycation biomarkers. Investigational glycation biomarkers are in development for: (i) healthy aging; (ii) risk prediction of vascular complications of diabetes; (iii) diagnosis of autism; and (iv) diagnosis and classification of early-stage arthritis. Protein glycation biomarkers are influenced by heritability, aging, decline in metabolic, vascular, renal and skeletal health, and other factors. They are applicable to populations of differing ethnicities, bridging the gap between genotype and phenotype. They are thereby likely to find continued and expanding clinical use, including in the current era of developing precision medicine, reporting on multiple pathogenic processes and supporting a precision medicine approach., Graphical abstract Image 1, Highlights • Clinical glycation biomarkers are: A1C, glycated albumin and serum fructosamine. • Advanced glycation endproduct (AGE) biomarkers are in development. • Applications include: diabetes, diabetic complications, arthritis, autism and aging. • They are influenced by genetics, aging, glucose metabolism and other factors. • Applicable to all ethnicities, they bridge the gap between genotype and phenotype.

The reactive dicarbonyl metabolite, methylglyoxal (MG), is increased in obesity and diabetes and is implicated in the development of insulin resistance, type 2 diabetes mellitus and vascular complications of diabetes. Dicarbonyl stress is the metabolic state of abnormal high MG concentration. MG is an arginine-directed glycating agent and precursor of the major advanced glycation endproduct, arginine-derived hydroimidazolone MG-H1. MG-H1 is often formed on protein surfaces and an uncharged hydrophobic residue, inducing protein structural distortion and misfolding. Recent studies indicate that dicarbonyl stress in human endothelial cells and fibroblasts in vitro induced a proteomic response consistent with activation of the unfolded protein response (UPR). The response included: increased abundance of heat shock proteins and ubiquitin ligases catalysing the removal of proteins with unshielded surface hydrophobic patches and formation of polyubiquitinated chains to encapsulate misfolded proteins; and increased low grade inflammation. Activation of the UPR is implicated in insulin resistance. An effective strategy to counter increased MG is inducing increased expression of glyoxalase-1 (Glo1). An optimized inducer of Glo1 expression, trans-resveratrol and hesperetin combination, normalized increased MG concentration, corrected insulin resistance and decreased low grade inflammation in overweight and obese subjects. We propose that dicarbonyl stress, through increased formation of MG-glycated proteins, may be an important physiological stimulus of the UPR and Glo1 inducers may provide a route to effective suppression and therapy. With further investigation and validation, this may provide key new insight into physiological activators of the UPR and association with dicarbonyl stress.

Metabolic dysfunction of endothelial cells in hyperglycemia contributes to the development of vascular complications of diabetes where increased reactive glycating agent, methylglyoxal (MG), is involved. We assessed if increased MG glycation induced proteotoxic stress, identifying related metabolic drivers and protein targets. Human aortal endothelial cells (HAECs) were incubated in high glucose concentration (20 mM versus 5 mM control) in vitro for 3–6 days. Flux of glucose metabolism, MG formation and glycation and changes in cytosolic protein abundances, MG modification and proteotoxic responses were assessed. Similar studies were performed with human microvascular endothelial HMEC-1 cells where similar outcomes were observed. HAECs exposed to high glucose concentration showed increased cellular concentration of MG (2.27 ± 0.21 versus 1.28 ± 0.03 pmol/106 cells, P 6 cells/day; P trans-Resveratrol and hesperetin combination (tRES-HESP) corrected increased MG and glucose metabolism by increasing expression of Glo1 and decreasing expression of HK-2. Increased MG glycation activates the UPR in endothelial cells and thereby may contribute to endothelial cell dysfunction in diabetic vascular disease where tRES-HESP may provide effective therapy.

The global pandemic of COVID-19 disease caused by infection with the SARS-CoV-2 Coronavirus, has produced an urgent requirement and search for improved treatments whilst effective vaccines are developed. A strategy for improved drug therapy is to increase levels of endogenous reactive metabolites for selective toxicity to SARS-CoV-2 by preferential damage to the viral proteome. Key reactive metabolites producing major quantitative damage to the proteome in physiological systems are: Reactive oxygen species (ROS) and the reactive glycating agent methylglyoxal (MG); cysteine residues and arginine residues are their most susceptible targets, respectively. From sequenced-based prediction of the SARS-CoV-2 proteome, we found 0.8-fold enrichment or depletion of cysteine residues in functional domains of the viral proteome; whereas there was a 4.6-fold enrichment of arginine residues, suggesting SARS-CoV-2 is resistant to oxidative agents and sensitive to MG. We examined activated arginine residues in functional domain with predicted low pKa by neighboring group interaction in the SARS-CoV-2. We found 25 such arginine residues, including 2 in the spike protein and 10 in the nucleoprotein. These sites were partially conserved in related coronaviridae: SARS-COV and MERS. We also screened and identified drugs, which increase cellular MG concentration to virucidal levels and found two antitumor drugs with historical antiviral activity, doxorubicin and paclitaxel were the best candidate for repurposing. Our findings provide evidence of potential vulnerability of SARS-CoV2 to inactivation by MG and a scientific rationale for repurposing of doxorubicin and paclitaxel for treatment of COVID-19 disease, providing efficacy and adequate therapeutic index may be established.

Increased protein glycation, oxidation and nitration is linked to the development of diabetic nephropathy. We reported levels of serum protein glycation, oxidation and nitration and related hydrolysis products, glycation, oxidation and nitration free adducts in patients with type 1 diabetes (T1DM) during onset of microalbuminuria (MA) from the First Joslin Kidney Study, a prospective case–control study of patients with T1DM with and without early decline in GFR. Herein we report urinary excretion of the latter analytes and related fractional excretion values, exploring the link to MA and early decline in GFR. We recruited patients with T1DM and normoalbuminuria (NA) (n = 30) or new onset MA with and without early GFR decline (n = 22 and 33, respectively) for this study. We determined urinary protein glycation, oxidation and nitration free adducts by stable isotopic dilution analysis liquid chromatography-tandem mass spectrometry (LC–MS/MS) and deduced fractional excretion using reported plasma levels and urinary and plasma creatinine estimates. We found urinary excretion of pentosidine was increased ca. twofold in patients with MA, compared to normoalbuminuria (0.0442 vs 0.0103 nmol/mg creatinine, P ca. threefold in patients with early decline in GFR, compared to patients with stable GFR (0.0561 vs 0.0176 nmol/mg creatinine, P

IntroductionPatients with diabetes have increased risk of periodontal disease, with increased risk of weakening of periodontal ligament and tooth loss. Periodontal ligament is produced and maintained by periodontal ligament fibroblasts (PDLFs). We hypothesized that metabolic dysfunction of PDLFs in hyperglycemia produces an accumulation of the reactive glycating agent, methylglyoxal (MG), leading to increased formation of the major advanced glycation endproduct, MG-H1 and PDLF dysfunction. The aim of this study was to assess if there is dicarbonyl stress and functional impairment of human PDLFs in primary culture in high glucose concentration—a model of hyperglycemia, to characterize the metabolic drivers of it and explore remedial intervention by the glyoxalase 1 inducer dietary supplement, trans-resveratrol and hesperetin combination (tRES-HESP).Research design and methodsHuman PDLFs were incubated in low and high glucose concentration in vitro. Metabolic and enzymatic markers of MG and glucose control were quantified and related changes in the cytoplasmic proteome and cell function—binding to collagen-I, assessed. Reversal of PDLF dysfunction by tRES-HESP was explored.ResultsIn high glucose concentration cultures, there was a ca. twofold increase in cellular MG, cellular protein MG-H1 content and decreased attachment of PDLFs to collagen-I. This was driven by increased hexokinase-2 linked glucose metabolism and related increased MG formation. Proteomics analysis revealed increased abundance of chaperonins, heat shock proteins (HSPs), Golgi-to-endoplasmic reticulum transport and ubiquitin E3 ligases involved in misfolded protein degradation in high glucose concentration, consistent with activation of the unfolded protein response by increased misfolded MG-modified proteins. PDLF dysfunction was corrected by tRES-HESP.ConclusionsIncreased hexokinase-2 linked glucose metabolism produces dicarbonyl stress, increased MG-modified protein, activation of the unfolded protein response and functional impairment of PDLFs in high glucose concentration. tRES-HESP resolves this at source by correcting increased glucose metabolism and may be of benefit in prevention of diabetic periodontal disease.

Significance: Obesity and type 2 diabetes mellitus are increasing globally. There is also increasing associated complications, such as non-alcoholic fatty liver disease (NAFLD) and vascular complications of diabetes. There is currently no licensed treatment for NAFLD and no recent treatments for diabetic complications. New approaches are required, particularly those addressing mechanism-based risk factors for health decline and disease progression.\ud \ud Recent Advances: Dicarbonyl stress is the abnormal accumulation of reactive dicarbonyl metabolites such as methylglyoxal (MG) leading to cell and tissue dysfunction. It is a potential driver of obesity, diabetes, and related complications that are unaddressed by current treatments. Increased formation of MG is linked to increased glyceroneogenesis and hyperglycemia in obesity and diabetes and also down-regulation of glyoxalase 1 (Glo1)—which provides the main enzymatic detoxification of MG. Glo1 functional genomics studies suggest that increasing Glo1 expression and activity alleviates dicarbonyl stress; slows development of obesity, related insulin resistance; and prevents development of diabetic nephropathy and other microvascular complications of diabetes. A new therapeutic approach constitutes small-molecule inducers of Glo1 expression—Glo1 inducers—exploiting a regulatory antioxidant response element in the GLO1 gene. A prototype Glo1 inducer, trans-resveratrol (tRES)-hesperetin (HESP) combination, in corrected insulin resistance, improved glycemic control and vascular inflammation in healthy overweight and obese subjects in clinical trial.\ud \ud Critical Issues: tRES and HESP synergize pharmacologically, and HESP likely overcomes the low bioavailability of tRES by inhibition of intestinal glucuronosyltransferases.\ud \ud Future Directions: Glo1 inducers may now be evaluated in Phase 2 clinical trials for treatment of NAFLD and vascular complications of diabetes.

Ischemic strokes are associated with significant morbidity and mortality, but currently there are no reliable prognostic or diagnostic blood biomarkers. MicroRNAs (miRNAs) regulate various molecular pathways and may be used as biomarkers. Using RNA-Seq, we conducted comprehensive circulating miRNA profiling in patients with ischemic stroke compared with healthy controls. Samples were collected within 24 h of clinical diagnosis. Stringent analysis criteria of discovery (46 cases and 95 controls) and validation (47 cases and 96 controls) cohorts led to the identification of 10 differentially regulated miRNAs, including 5 novel miRNAs, with potential diagnostic significance. Hsa-miR-451a was the most significantly upregulated miRNA (FC; 4.8, FDR; 3.78 × 10−85), while downregulated miRNAs included hsa-miR-574-5p and hsa-miR-142-3p, among others. Importantly, we computed a multivariate classifier based on the identified miRNA panel to differentiate between ischemic stroke patients and healthy controls, which showed remarkably high sensitivity (0.94) and specificity (0.99). The area under the ROC curve was 0.97 and it is superior to other current available biomarkers. Moreover, in samples collected one month following stroke, we found sustained upregulation of hsa-miR-451a and downregulation of another 5 miRNAs. Lastly, we report 3 miRNAs that were significantly associated with poor clinical outcomes of stroke, as defined by the modified Rankin scores. The clinical translation of the identified miRNA panel may be explored further.

The recent discovery of the glucose-induced stabilization of hexokinase-2 (HK2) to proteolysis in cell dysfunction in model hyperglycemia has revealed a likely key initiating factor contributing to the development of insulin resistance and vascular complications in diabetes. Consequently, the increased flux of glucose metabolism without a change in the expression and activity of glycolytic enzymes produces a wave of increased glycolytic intermediates driving mitochondrial dysfunction and increased reactive oxygen species (ROS) formation, the activation of hexosamine and protein kinase C pathways, the increased formation of methylglyoxal-producing dicarbonyl stress, and the activation of the unfolded protein response. This is called HK2-linked glycolytic overload and unscheduled glycolysis. The conditions required to sustain this are GLUT1 and/or GLUT3 glucose uptake and the expression of HK2. A metabolic biomarker of its occurrence is the abnormally increased deposition of glycogen, which is produced by metabolic channeling when HK2 becomes detached from mitochondria. These conditions and metabolic consequences are found in the vasculature, kidneys, retina, peripheral nerves, and early-stage embryo development in diabetes and likely sustain the development of diabetic vascular complications and embryopathy. In insulin resistance, HK2-linked unscheduled glycolysis may also be established in skeletal muscle and adipose tissue. This may explain the increased glucose disposal by skeletal uptake in the fasting phase in patients with type 2 diabetes mellitus, compared to healthy controls, and the presence of insulin resistance in patients with type 1 diabetes mellitus. Importantly, glyoxalase 1 inducer—trans-resveratrol and hesperetin in combination (tRES-HESP)—corrected HK2-linked glycolytic overload and unscheduled glycolysis and reversed insulin resistance and improved vascular inflammation in overweight and obese subjects in clinical trial. Further studies are now required to evaluate tRES-HESP for the prevention and reversal of early-stage type 2 diabetes and for the treatment of the vascular complications of diabetes.

Advanced glycation end products (AGEs) are stable posttranslational modifications of proteins formed by the spontaneous reaction with glucose and related metabolites. Important AGEs quantitatively are methylglyoxal (MG)-derived hydroimidazolone MG-H1, N e -carboxymethyl-lysine (CML), and glucosepane. They contribute to the development of chronic kidney disease (CKD). Cellular proteolysis of AGE-modified proteins forms AGE free adducts, glycated amino acids, which are cleared by the kidneys and excreted in urine. Dietary AGEs mainly supplement the endogenous flux of AGE free adduct formation. AGE free adducts accumulate markedly in plasma with decline in glomerular filtration rate. A key precursor of AGEs is the dicarbonyl metabolite MG, which is metabolized by glyoxalase 1 (Glo1) of the cytoplasmic glyoxalase system. Proteins susceptible to MG modification are collectively called the dicarbonyl proteome. Abnormal increase of MG dicarbonyl stress is a characteristic of CKD, driven by down-regulation of renal Glo1, increasing flux of MG-H1 formation. Protein inactivation and dysfunction linked to the dicarbonyl proteome contributes to CKD development. The receptor for AGEs, RAGE, is important in development of CKD, but its interaction with AGEs in vivo remains enigmatic; other ligands and ternary complexation may be influential. Prevention of diabetic kidney disease (DKD) by overexpression of Glo1 in transgenic animal models has stimulated the development of small-molecule inducers of Glo1 expression, Glo1 inducers, to prevent AGE formation. trans -Resveratrol–hesperetin combination therapy is a Glo1 inducer. In clinical trial it demonstrated a profound improvement in insulin resistance and vascular inflammation. It may find future therapeutic application for treatment of DKD.

Autism spectrum disorders (ASD) are a collection of neuropsychiatric disorders. ASD affects 1 in 87 in Qatar and is expected to increase. The high variability and heterogeneity of the symptoms makes diagnosis of ASD difficult and uncertain, particularly at the early stages of development. If detected early, clinical support can be given to promote optimal development and well-being of children with ASD and even achieve complete remission. The current method of diagnosing ASD is by observations and interviews made by experts in child development to assess child behavior, communication and cognition: the ADOS test. There is often delay in referral for expert diagnosis; delay is typically >18 months in Qatar and >4 years in EU and USA. The diagnostic accuracy is 60 – 70%. Mutations in proteins transporters of amino acids have been linked to some cases of ASD. We hypothesized that levels of amino acids in blood, including amino acids damaged by modification by sugars (glycation), oxidation and nitration may provide novel biomarker for diagnosis of ASD at very young age.

Dicarbonyl stress is defined as the abnormal accumulation of reactive α-oxoaldehyde, dicarbonyl metabolites leading to cell and tissue dysfunction implicated in aging and disease. There is increased formation of arginine-derived hydroimidazolone adducts of proteins and guanosine-derived imidazopurinone adducts of DNA, linked to protein misfolding and mutagenesis, respectively. Methylglyoxal is a dominant mediator of dicarbonyl stress in vivo. It is metabolized by glutathione-dependent glyoxalase 1 (Glo1). The main drivers of dicarbonyl stress are increased formation of methylglyoxal by glycolytic overload and decreased metabolism of methylglyoxal by downregulation of Glo1. Proteins susceptible to dicarbonyl modification are enriched in protein folding, protein synthesis, and glucose metabolism. Dicarbonyl stress activates the unfolded protein response and downstream proinflammatory and prothrombotic responses. The pathobiology of dicarbonyl stress is most evident in obesity, vascular complications of diabetes, cardiovascular disease, renal failure, and aging. It may be corrected by dicarbonyl scavengers and inducers of Glo1 expression.

Endothelial dysfunction contributes to the development of vascular complications of diabetes. Hyperglycemia induces multiple pathways of metabolic dysfunction: mitochondrial dysfunction, hexosamine and protein kinase C pathway activation and increased formation of methylglyoxal (MG). We recently showed that increased glucose metabolism driving this is produced by glucose-induced stabilization of hexokinase-2 (HK2) to proteolysis, increasing HK2 activity. In this study we investigated correction of this by combination of resveratrol and hesperetin (tRES-HESP) which induces expression of glyoxalase 1 (Glo1) and protects against increased MG. Human aortal endothelial cells (HAECs) were incubated in primary culture with 5 mM or 20 mM glucose for 6 days with and without 10 µM tRES-HESP. Glucose consumption and flux of MG formation was measured by enzymatic assay. Activity of glyoxalase 1 (Glo1) was measured by spectrophotometric assay. HK2 protein was determined by Western blotting. The flux of glucose consumption in high glucose concentration cultures of HAECs was increased, compared to low glucose concentration control (1647 ± 242 vs. 748 ± 150 nmol/106 cells/day, n = 8; +120%, P Disclosure P. Thornalley: None. A.A. Ashour: None. M. Xue: None. N. Rabbani: None.

Dysfunction of human periodontal ligament fibroblasts (PDLFs) contributes to increased prevalence and severity of periodontitis in diabetes. Hyperglycemia induces multiple pathways of metabolic dysfunction: mitochondrial dysfunction, hexosamine and protein kinase C pathway activation and increased formation of methylglyoxal (MG) in human periodontal ligament fibroblasts in vitro. We recently showed that increased glucose metabolism driving metabolic dysfunction in hyperglycemia is produced by glucose-induced stabilization of hexokinase-2 (HK2) to proteolysis, increasing HK2 activity. In this study we investigated correction of this by combination of resveratrol and hesperetin (tRES-HESP) which induces expression of glyoxalase 1 (Glo1) and protects against increased MG. Human PDLFs were incubated in primary culture with 8 mM or 25 mM glucose for 3 days with and without 10 µM tRES-HESP. Glucose consumption and flux of MG formation was measured by enzymatic assay. Activity of glyoxalase 1 (Glo1) was measured by spectrophotometric assay. HK2 protein was determined by Western blotting. The flux of glucose consumption in high glucose concentration cultures of PDLFs was increased, compared to low glucose concentration control (10,658 ± 1,141 vs. 5,923 ± 706 nmol/106 cells/day, n = 3; +80%, P Disclosure N. Rabbani: None. A.A. Ashour: None. M. Xue: None. P. Thornalley: None.

Hexokinase-2 (HK2) was recently found to produce increased metabolic flux through glycolysis in hyperglycemia without concurrent transcriptional or other functional regulation. Rather, stabilization to proteolysis by increased glucose substrate binding produced unscheduled increased glucose metabolism in response to high cytosolic glucose concentration. This produces abnormal increases in glycolytic intermediates or glycolytic overload, driving cell dysfunction and vulnerability to the damaging effects of hyperglycemia in diabetes, explaining tissue-specific pathogenesis. Glycolytic overload is also activated in ischemia–reperfusion injury and cell senescence. A further key feature is HK2 displacement from mitochondria by increased glucose-6-phosphate concentration, inducing mitochondrial dysfunction and oxidative stress. This pathogenic mechanism suggested new targets for therapeutics development that gave promising outcomes in initial clinical evaluation.

Background Clinical chemistry tests for autism spectrum disorder (ASD) are currently unavailable. The aim of this study was to explore the diagnostic utility of proteotoxic biomarkers in plasma and urine, plasma protein glycation, oxidation, and nitration adducts, and related glycated, oxidized, and nitrated amino acids (free adducts), for the clinical diagnosis of ASD. Methods Thirty-eight children with ASD (29 male, 9 female; age 7.6 ± 2.0 years) and 31 age-matched healthy controls (23 males, 8 females; 8.6 ± 2.0 years) were recruited for this study. Plasma protein glycation, oxidation, and nitration adducts and amino acid metabolome in plasma and urine were determined by stable isotopic dilution analysis liquid chromatography-tandem mass spectrometry. Machine learning methods were then employed to explore and optimize combinations of analyte data for ASD diagnosis. Results We found that children with ASD had increased advanced glycation endproducts (AGEs), Nε-carboxymethyl-lysine (CML) and Nω-carboxymethylarginine (CMA), and increased oxidation damage marker, dityrosine (DT), in plasma protein, with respect to healthy controls. We also found that children with ASD had increased CMA free adduct in plasma ultrafiltrate and increased urinary excretion of oxidation free adducts, alpha-aminoadipic semialdehyde and glutamic semialdehyde. From study of renal handling of amino acids, we found that children with ASD had decreased renal clearance of arginine and CMA with respect to healthy controls. Algorithms to discriminate between ASD and healthy controls gave strong diagnostic performance with features: plasma protein AGEs—CML, CMA—and 3-deoxyglucosone-derived hydroimidazolone, and oxidative damage marker, DT. The sensitivity, specificity, and receiver operating characteristic area-under-the-curve were 92%, 84%, and 0.94, respectively. Conclusions Changes in plasma AGEs were likely indicative of dysfunctional metabolism of dicarbonyl metabolite precursors of AGEs, glyoxal and 3-deoxyglucosone. DT is formed enzymatically by dual oxidase (DUOX); selective increase of DT as an oxidative damage marker implicates increased DUOX activity in ASD possibly linked to impaired gut mucosal immunity. Decreased renal clearance of arginine and CMA in ASD is indicative of increased arginine transporter activity which may be a surrogate marker of disturbance of neuronal availability of amino acids. Data driven combination of these biomarkers perturbed by proteotoxic stress, plasma protein AGEs and DT, gave diagnostic algorithms of high sensitivity and specificity for ASD. Electronic supplementary material The online version of this article (10.1186/s13229-017-0183-3) contains supplementary material, which is available to authorized users.

Aims/hypothesis: To assess thiamine and related metabolite status by analysis of plasma and urine in autistic children and healthy controls, correlations to clinical characteristics and link to plasma protein markers of oxidative damage. Methods: 27 children with autism (21 males and 6 females) and 21 (15 males and 6 females) age-matched healthy control children were recruited. The concentration of thiamine and related phosphorylated metabolites in plasma and urine and plasma protein content of dityrosine, N-formylkynurenine and 3-nitrotyrosine was determined. Results: Plasma thiamine and thiamine monophosphate concentrations were similar in both study groups (median [lower–upper quartile]): autistic children–6.60 nM (4.48–8.91) and 7.00 nM (5.51–8.55), and healthy controls–6.82 nM (4.47–7.02) and 6.82 nM (5.84–8.91), respectively. Thiamine pyrophosphate (TPP) was decreased 24% in autistic children compared to healthy controls: 6.82 nM (5.81–8.52) versus 9.00 nM (8.41–10.71), p

Open Access article The glyoxalase system in the cytoplasm of cells provides the primary defence against glycation by methylglyoxal catalysing its metabolism to D-lactate. Methylglyoxal is the precursor of the major quantitative advanced glycation endproducts in physiological systems - arginine-derived hydroimidazolones and deoxyguanosine-derived imidazopurinones. Glyoxalase 1 of the glyoxalase system was linked to anthropometric measurements of obesity in human subjects and to body weight in strains of mice. Recent conference reports described increased weight gain on high fat diet-fed mouse with lifelong deficiency of glyoxalase 1 deficiency, compared to wild-type controls, and decreased weight gain in glyoxalase 1-overexpressing transgenic mice, suggesting a functional role of glyoxalase 1 and dicarbonyl stress in obesity. Increased methylglyoxal, dicarbonyl stress, in white adipose tissue and liver may be a mediator of obesity and insulin resistance and thereby a risk factor for development of type 2 diabetes and non-alcoholic fatty liver disease. Increased methylglyoxal formation from glyceroneogenesis on adipose tissue and liver and decreased glyoxalase 1 activity in obesity likely drives dicarbonyl stress in white adipose tissue increasing the dicarbonyl proteome and related dysfunction. The clinical significance will likely emerge from on-going clinical evaluation of inducers of glyoxalase 1 expression in overweight and obese subjects. Increased transcapillary escape rate of albumin and increased total body interstitial fluid volume in obesity likely makes levels of glycation of plasma protein unreliable indicators of glycation status in obesity as there is a shift of albumin dwell time from plasma to interstitial fluid, which decreases overall glycation for a given glycemic exposure

Risk of insulin resistance, impaired glycemic control, and cardiovascular disease is excessive in overweight and obese populations. We hypothesized that increasing expression of glyoxalase 1 (Glo1)—an enzyme that catalyzes the metabolism of reactive metabolite and glycating agent methylglyoxal—may improve metabolic and vascular health. Dietary bioactive compounds were screened for Glo1 inducer activity in a functional reporter assay, hits were confirmed in cell culture, and an optimized Glo1 inducer formulation was evaluated in a randomized, placebo-controlled crossover clinical trial in 29 overweight and obese subjects. We found trans-resveratrol (tRES) and hesperetin (HESP), at concentrations achieved clinically, synergized to increase Glo1 expression. In highly overweight subjects (BMI >27.5 kg/m2), tRES-HESP coformulation increased expression and activity of Glo1 (27%, P < 0.05) and decreased plasma methylglyoxal (−37%, P < 0.05) and total body methylglyoxal-protein glycation (−14%, P < 0.01). It decreased fasting and postprandial plasma glucose (−5%, P < 0.01, and −8%, P < 0.03, respectively), increased oral glucose insulin sensitivity index (42 mL ⋅ min−1 ⋅ m−2, P < 0.02), and improved arterial dilatation Δbrachial artery flow-mediated dilatation/Δdilation response to glyceryl nitrate (95% CI 0.13–2.11). In all subjects, it decreased vascular inflammation marker soluble intercellular adhesion molecule-1 (−10%, P < 0.01). In previous clinical evaluations, tRES and HESP individually were ineffective. tRES-HESP coformulation could be a suitable treatment for improved metabolic and vascular health in overweight and obese populations.

Recent research has identified glycation as a non-enzymatic post-translational modification of proteins in plants with a potential contributory role to the functional impairment of the plant proteome. Reducing sugars with a free aldehyde or ketone group such as glucose, fructose and galactose react with the N-terminal and lysine side chain amino groups of proteins. A common early-stage glycation adduct formed from glucose is N-fructosyl-lysine (FL). Saccharide-derived reactive dicarbonyls are arginine residue-directed glycating agents, forming advanced glycation endproducts (AGEs). A dominant dicarbonyl is methylglyoxal-formed mainly by the trace-level degradation of triosephosphates, including through the Calvin cycle of photosynthesis. Methylglyoxal forms the major quantitative AGE, hydroimidazolone MG-H1. Glucose and methylglyoxal concentrations in plants change with the developmental stage, senescence, light and dark cycles and also likely biotic and abiotic stresses. Proteomics analysis indicates that there is an enrichment of the amino acid residue targets of glycation, arginine and lysine residues, in predicted functional sites of the plant proteome, suggesting the susceptibility of proteins to functional inactivation by glycation. In this review, we give a brief introduction to glycation, glycating agents and glycation adducts in plants. We consider dicarbonyl stress, the functional vulnerability of the plant proteome to arginine-directed glycation and the likely role of methylglyoxal-mediated glycation in the activation of the unfolded protein response in plants. The latter is linked to the recent suggestion of protein glycation in sugar signaling in plant metabolism. The overexpression of glyoxalase 1, which suppresses glycation by methylglyoxal and glyoxal, produced plants resistant to high salinity, drought, extreme temperature and other stresses. Further research to decrease protein glycation in plants may lead to improved plant growth and assist the breeding of plant varieties resistant to environmental stress and senescence-including plants of commercial ornamental and crop cultivation value. Qatar University and HBKU, Qatar Foundation

Background Glycation, oxidation and nitration of proteins are reactions involved in accelerated ageing of tissues. The products of these reactions are used as biomarkers of chronic pathologies such as diabetes or chronic inflammatory states. Objectives In this work, we studied by mass spectrometry the levels of amino acids and glycated, oxidised or nitrated proteins in culture media of chondrocytes cultivated in multi-layers and in the blood of guinea pigs or osteoarthritis patients. Methods Sixty male, 3-week-old Dunkin-Hartley guinea pigs were used in this work. At 4-weeks-old and 8 week intervals until week 36, twelve animals were sacrificed and histological severity of knee osteoarthritis evaluated and cartilage rheological properties. Human patients with early and advanced osteoarthritis and healthy subjects were recruited. Human chondrocytes cultured in multilayers were treated for 10 days with interleukin (IL) −1β. Amino acids and glycated, oxidised and nitrated proteins were analysed in the serum of guinea pigs, osteoarthritis patients and in the culture medium conditioned by chondrocytes by stable isotopic dilution analysis liquid chromatography-tandem mass spectrometry using the Acquity UPLC system. Results Severity of osteoarthritis increased progressively in guinea pigs with age. Glycated, oxidised and nitrated amino acids were increased markedly at week 36. Glucosepane and dityrosine increased progressively from weeks 20 and 28, respectively. Glucosepane was positively correlated with the OA histological severity (r=0.58, p Conclusions The glycation, oxidation and nitration of proteins are reactions related to the severity of osteoarthritis. The products of these reactions are measurable in blood by mass spectrometry and could be biomarkers of osteoarthritis. More specifically, glucosepane is an advanced glycation product very strongly increased in the severe form of the disease. In conclusion, serum glucosepane is a potential biomarker for diagnosis and progression of osteoarthritis. Disclosure of Interest None declared