Aims/hypothesis A long-term 'memory' of hyperglycaemic stress, even when glycaemia is normalised, has been previously reported in endothelial cells. In this report we sought to duplicate and extend this finding. Materials and methods HUVECs and ARPE-19 retinal cells were incubated in 5 or in 30 mmol/l glucose for 3 weeks or subjected to 1 week of normal glucose after being exposed for 2 weeks to continuous high glucose. HUVECs were also treated in this last condition with several antioxidants. Similarly, four groups of rats were studied for 3 weeks: (1) normal rats; (2) diabetic rats not treated with insulin; (3) diabetic rats treated with insulin during the last week; and (4) diabetic rats treated with insulin plus α-lipoic acid in the last week. Results In human endothelial cells and ARPE-19 retinal cells in culture, as well as in the retina of diabetic rats, levels of the following markers of high glucose stress remained induced for 1 week after levels of glucose had normalised: protein kinase C-β, NAD(P)H oxidase subunit p47phox, BCL-2-associated X protein, 3-nitrotyrosine, fibronectin, poly(ADPribose) Blockade of reactive species using different approaches, i.e. the mitochondrial antioxidant α-lipoic acid, overexpression of uncoupling protein 2, oxypurinol, apocynin and the poly(ADP-ribose) polymerase inhibitor PJ34, interrupted the induction both of high glucose stress markers and of the fluorescent reactive oxygen species (ROS) probe CM-H 2 DCFDA in human endothelial cells. Similar results were obtained in the retina of diabetic rats with α-lipoic acid added to the last week of normalised glucose. Conclusions/interpretation These results provide proofof-principle of a ROS-mediated cellular persistence of vascular stress after glucose normalisation.

The T-state crystal structure of the glucose-phosphorylase b complex has been used as a model for the design of glucose analogue inhibitors that may be effective in the regulation of blood glucose levels. Modeling studies indicated room for additional atoms attached at the C1-beta position of glucose and some scope for additional atoms at the C1-alpha position. Kinetic parameters were determined for alpha-D-glucose: Ki = 1.7 mM, Hill coefficient n = 1.5, and alpha (synergism with caffeine) = 0.2. For beta-D-glucose, Ki = 7.4 mM, n = 1.5, and alpha = 0.4. More than 20 glucose analogues have been synthesized and tested in kinetic experiments. Most were less effective inhibitors than glucose itself and the best inhibitor was alpha-hydroxymethyl-1-deoxy-D-glucose (Ki = 1.5 mM, n = 1.3, alpha = 0.4). The binding of 14 glucose analogues to glycogen phosphorylase b in the crystal has been studied at 2.4-A resolution and the structure have been refined to crystallographic R values of less than 0.20. The kinetic and crystallographic studies have been combined to provide rationalizations for the apparent affinities of glucose and the analogues. The results show the discrimination against beta-D-glucose in favor of alpha-D-glucose is achieved by an additional hydrogen bond made in the alpha-glucose complex through water to a protein group and an unfavorable environment for a polar group in the beta pocket. The compound alpha-hydroxymethyl-1-deoxy-D-glucose has an affinity similar to that of glucose and makes a direct hydrogen bond to a protein group. Comparison of analogues with substituent atoms that have flexible geometry (e.g., 1-hydroxyethyl beta-D-glucoside) with those whose substituent atoms are more rigid (e.g., beta-azidomethyl-1-deoxyglucose or beta-cyanomethyl-1-deoxyglucose) indicates that although all three compounds make similar polar interactions with the enzyme, those with more rigid substituent groups are better inhibitors. In another example, alpha-azidomethyl-1-deoxyglucose was a poor inhibitor. In the crystal structure the compound made several favorable interactions with the enzyme but bound in an unfavorable conformation, thus providing an explanation for its poor inhibition. Attempts to utilize a contact to a buried aspartate group were partially successful for a number of compounds (beta-aminoethyl, beta-mesylate, and beta-azidomethyl analogues). The beta pocket was shown to bind gentiobiose (6-O-beta-D-glucopyranosyl-D-glucose), indicating scope for binding of larger side groups for future studies.

Dietary fatty acids have a profound impact on atherosclerosis, but mechanisms are not fully understood. We studied the effects of a saturated fat diet supplemented with fish oil, trans10,cis12 conjugated linoleic acid (CLA), or elaidic acid on lipid and glucose metabolism and liver protein levels of APOE*3 Leiden transgenic mice, a model for lipid metabolism and atherosclerosis. Fish oil lowered plasma and liver cholesterol and triglycerides, plasma free fatty acids, and glucose but increased plasma insulin. CLA lowered plasma cholesterol but increased plasma and liver triglycerides, plasma beta-hydroxybutyrate, and insulin. Elaidic acid lowered plasma and liver cholesterol. Proteomics identified significant regulation of 65 cytosolic and 8-membrane proteins. Many of these proteins were related to lipid and glucose metabolism, and to oxidative stress. Principal component analysis revealed that fish oil had a major impact on cytosolic proteins, and elaidic acid on membrane proteins. Correlation analysis between physiological and protein data revealed novel clusters of correlated variables, among which a metabolic syndrome cluster. The combination of proteomics and physiology gave new insights in mechanisms by which these dietary fatty acids regulate lipid metabolism and related pathways, for example, by altering protein levels of long-chain acyl-CoA thioester hydrolase and adipophilin in the liver.

Conjugated linoleic acids (CLA) affect atherogenesis, but mechanisms are not well understood. We explored how two isomers of CLA, cis9, trans11-CLA and trans10, cis12-CLA, affected lipid and glucose metabolism, as well as hepatic protein expression, in apolipoprotein E knockout mice. After 12 wk of intervention, plasma triglyceride, NEFA, and glucose concentrations were significantly higher in the trans10, cis12-CLA group, whereas plasma triglyceride, NEFA, glucose, and insulin concentrations were significantly lower in the cis9, trans11-CLA group, compared with control mice consuming linoleic acid. Proteomics identified significant up- or down-regulation of 113 liver cytosolic proteins by either CLA isomer. Principal component analysis revealed that the treatment effect of cis9, trans11-CLA was mainly explained by the up-regulation of different posttranslational forms of heat shock protein 70 kD. In contrast, the treatment effect of trans10, cis12-CLA was mainly explained by up-regulation of key enzymes in the gluconeogenic, beta-oxidation, and ketogenesic pathways. Correlation analysis again emphasized the divergent effects of both CLA isomers on different pathways, but also revealed a linkage between insulin resistance and increased levels of hepatic serotransferrin. Thus, our systems biology approach provided novel insights into the mechanisms by which individual CLA isomers differentially affect pathways related to atherogenesis, such as insulin resistance and inflammation.

PurposeLow fruit and vegetable consumption is linked with an increased risk of death from vascular disease and cancer. The benefit of eating fruits and vegetables is attributed in part to antioxidants, vitamins and phytochemicals. Whether increasing intake impacts on markers of disease remains to be established. This study investigates whether increasing daily intake of fruits, vegetables and juices from low (approx. 3 portions), to high intakes (approx. 8 portions) impacts on nutritional and clinical biomarkers. Barriers to achieving the recommended fruit and vegetable intakes are also investigated.MethodIn a randomised clinical trial, the participants [19 men and 26 women (39–58 years)] with low reported fruit, juice and vegetable intake (<3 portions/day) were randomised to consume either their usual diet or a diet supplemented with an additional 480 g of fruit and vegetables and fruit juice (300 ml) daily for 12 weeks. Nutritional biomarkers (vitamin C, carotenoids, B vitamins), antioxidant capacity and genomic stability were measured pre-intervention, at 4-, 8- and 12 weeks throughout the intervention. Samples were also taken post-intervention after a 6-week washout period. Glucose, homocysteine, lipids, blood pressure, weight and arterial stiffness were also measured. Intake of fruit, fruit juice and vegetables was reassessed 12 months after conducting the study and a questionnaire was developed to identify barriers to healthy eating.ResultsIntake increased significantly in the intervention group compared to controls, achieving 8.4 portions/day after 12 weeks. Plasma vitamin C (35%), folate (15%) and certain carotenoids [α-carotene (50%) and β-carotene (70%) and lutein/zeaxanthin (70%)] were significantly increased (P < 0.05) in the intervention group. There were no significant changes in antioxidant capacity, DNA damage and markers of vascular health. Barriers to achieving recommended intakes of fruits and vegetables measured 12 months after the intervention period were amount, inconvenience and cost.ConclusionWhile increasing fruit, juice and vegetable consumption increases circulating level of beneficial nutrients in healthy subjects, a 12-week intervention was not associated with effects on antioxidant status or lymphocyte DNA damage.Trial registrationThis trial was registered at Controlled-Trials.com; registration ISRCTN71368072.Electronic supplementary materialThe online version of this article (doi:10.1007/s00394-017-1469-0) contains supplementary material, which is available to authorized users.