European Journal of Nutrition (v.55, #8)
Hyperglycemia-associated alterations in cellular signaling and dysregulated mitochondrial bioenergetics in human metabolic disorders by George B. Stefano; Sean Challenger; Richard M. Kream (2339-2345).
The severity of untreated or refractory diabetes mellitus has been functionally linked to elevated concentrations of free plasma glucose, clinically defined as hyperglycemia. Operationally, the pathophysiological presentations of prolonged hyperglycemia may be categorized within insulin-dependent and insulin-independent, type 1 and type 2 diabetic phenotypes, respectively. Accordingly, major areas of empirical biomedical research have focused on the elucidation of underlying mechanisms driving key cellular signaling systems that are significantly altered in patients presenting with diabetes-associated chronic hyperglycemia.Presently, we provide a translationally oriented review of key studies evaluating the aberrant effects of hyperglycemia on two major signaling pathways linked to debilitating cellular and systemic effects via targeted disruption of mitochondrial bioenergetics: (1) advanced glycation end-products (AGEs)/and their cognate receptor for advanced glycation end-products (RAGEs), and (2) the hexosamine biosynthetic pathway (HBP).In preclinical models, cultured vascular endothelial cells exposed to hyperglycemic glucose concentrations were observed to produce enhanced levels of reactive oxygen species (ROS) functionally linked to increased formation of AGEs and expression of their cognate RAGEs. Importantly, inhibitors of AGEs formation, mitochondrial complex II, or un-couplers of oxidative phosphorylation, were observed to significantly reduce the effects of hyperglycemia on ROS production and cellular damage, thereby establishing a critical linkage to multiple levels of mitochondrial functioning. Hyperglycemia-mediated enhancement of mitochondrial ROS/superoxide production in vascular endothelial cells has been functionally linked to the shunting of glucose into the HBP with resultant long-term activation of pro-inflammatory signaling processes. Additionally, exposure of cultured cells to hyperglycemic conditions resulted in enhanced HBP-mediated inhibition of protein subunits of mitochondrial respiratory complexes I, III, and IV, intimately associated with normative cellular bioenergetics and ATP production.Convergent lines of evidence link chronic hyperglycemic conditions to aberrant expression of AGEs/RAGEs and HBP signaling pathways in relation to the pathophysiological formation of ROS and pro-inflammatory processes on the functional dysregulation of mitochondrial bioenergetics.
Keywords: Mitochondria; Glucose; Hyperglycemia; Diabetes; ATP; Aerobic glycolysis; Advanced glycation end-products; Receptor for advanced glycation end-products; Hexosamine biosynthetic pathway; Hexosamine biosynthetic pathway
Intake and sources of added sugars among Australian children and adolescents by Jimmy Chun Yu Louie; Hanieh Moshtaghian; Anna M. Rangan; Victoria M. Flood; Timothy P. Gill (2347-2355).
To examine the intake and sources of added sugars (AS) of Australian children and adolescents, and compare their intake of free sugars (FS) to the recommended limit set by the World Health Organization (<10 % energy from FS).Data of 4140 children and adolescents aged 2–16 years with plausible intakes based on 2 × 24 h recalls from the 2007 Australian National Children Nutrition and Physical Activity Survey were used. AS content of foods was estimated based on a published method. Intakes of AS and FS, as well as food sources of AS, were calculated. One-way ANOVA was used for comparisons between age groups and gender.The mean (SD) AS intake was 58.9 (35.1) g/day, representing 11.9 (5.6) % of daily energy intake and 46.9 (17.5) % of daily total sugars intake. More than 80 % of the subjects had % energy from FS > 10 %. Significant increasing trends for AS intake, % energy from AS, % energy from FS across age groups were observed. Sugar-sweetened beverages (19.6 %), cakes, biscuits, pastries and batter-based products (14.3 %), and sugar and sweet spreads (10.5 %) were the top three contributors of AS intake in the whole sample. Higher contribution of AS from sugar-sweetened beverages was observed in adolescents (p trend < 0.001).A large proportion of Australian youths are consuming excessive amounts of energy from AS. Since the main sources of AS were energy-dense, nutrient-poor foods, interventions which target the reduction in these foods would reduce energy and AS intake with minimal impact to core nutrient intake.
Keywords: Free sugars; Added sugars; Australian; Children; Adolescents; Food sources
The effects of coenzyme Q10 administration on glucose homeostasis parameters, lipid profiles, biomarkers of inflammation and oxidative stress in patients with metabolic syndrome by Fariba Raygan; Zohreh Rezavandi; Sahar Dadkhah Tehrani; Alireza Farrokhian; Zatollah Asemi (2357-2364).
Limited data are available indicating the effects of coenzyme Q10 (CoQ10) supplementation on metabolic status of patients with metabolic syndrome (MetS).The present study was conducted to determine the effects of CoQ10 administration on glucose homeostasis parameters, lipid profiles, biomarkers of inflammation and oxidative stress among patients with MetS.This randomized, double-blind, placebo-controlled trial was performed among 60 overweight or obese and type 2 diabetes mellitus patients with coronary heart disease aged 40–85 years old. Participants were randomly allocated into two groups. Group A (n = 30) received 100 mg CoQ10 supplements and group B (n = 30) received placebo for 8 weeks. Fasting blood samples were taken at the beginning of the study and after 8-week intervention to quantify glucose homeostasis parameters, lipid profiles and biomarkers of inflammation and oxidative stress.Compared with the placebo, CoQ10 supplementation resulted in a significant reduction in serum insulin levels (−2.1 ± 7.1 vs. +4.1 ± 7.8 µIU/mL, P = 0.002) and homeostasis model of assessment-insulin resistance (−0.7 ± 2.1 vs. +1.0 ± 2.0, P = 0.002) and homeostatic model assessment-beta cell function (−5.9 ± 22.2 vs. +15.9 ± 34.0, P = 0.005). In addition, patients who received CoQ10 supplements had a significant increase in plasma total antioxidant capacity (TAC) concentrations (+26.0 ± 105.0 vs. −162.2 ± 361.8 mmol/L, P = 0.008) compared with the placebo group. However, after adjustment for the baseline levels, age and baseline BMI, the effect on TAC levels (P = 0.08) disappeared. Additionally, compared with the placebo group, a significant positive trends in plasma glutathione (P = 0.06) and a significant reduction in malondialdehyde (P = 0.08) were seen among patients who received CoQ10 supplement. We did not observe any significant changes in fasting plasma glucose, lipid concentrations and inflammatory markers.Overall, daily intake of 100 mg CoQ10 supplements among patients with MetS for 8 weeks had beneficial effects on serum insulin levels, HOMA-IR, HOMA-B and plasma TAC concentrations. www.irct.ir : IRCT201502245623N35.
Keywords: Coenzyme Q10; Supplementation; Metabolic syndrome; Type 2 diabetes mellitus; Coronary heart disease
Postprandial insulin and glucose levels are reduced in healthy subjects when a standardised breakfast meal is supplemented with a filtered sugarcane molasses concentrate by Timothy P. Ellis; Alison G. Wright; Peter M. Clifton; Leodevico L. Ilag (2365-2376).
A phytochemical- and mineral-rich filtered sugarcane molasses concentrate (FMC), when added to carbohydrate-containing foods as a functional ingredient, lowers postprandial blood glucose and insulin responses. We hypothesised that this beneficial effect would also occur if FMC was administered as an oral supplement taken before a meal.This study measured the postprandial glucose and insulin responses elicited by different doses of FMC administered immediately prior to a standard breakfast to healthy subjects. Each subject was given three or five breakfast meals once, on different days. The composition of the meals was identical, except for the addition of either placebo syrup (test meal 1) or increasing doses of FMC (test meals 2–5).The plasma glucose concentration curves were similar for the five test meals. Plasma insulin curves were lowered in a dose-dependent manner. Stratifying subjects based on age, BMI and insulin resistance showed greater effects of low doses of FMC on lowering insulin responses in those subjects with potentially greater insulin resistance. When insulin response is standardised to amount of carbohydrate in the meal/dose combination, the reduction in response is linear and inversely proportional to the FMC dose.FMC shows promise as an agent that can reduce insulin responses and lessen the load on the pancreatic beta cells.
Keywords: Blood glucose; Insulin; Insulin resistance; Metabolic syndrome
Digestion of starch in a dynamic small intestinal model by M. R. Jaime-Fonseca; O. Gouseti; P. J. Fryer; M. S. J. Wickham; S. Bakalis (2377-2388).
The rate and extent of starch digestion have been linked with important health aspects, such as control of obesity and type-2 diabetes. In vitro techniques are often used to study digestion and simulated nutrient absorption; however, the effect of gut motility is often disregarded. The present work aims at studying fundamentals of starch digestion, e.g. the effect of viscosity on digestibility, taking into account both biochemical and engineering (gut motility) parameters.New small intestinal model (SIM) that realistically mimics gut motility (segmentation) was used to study digestibility and simulated oligosaccharide bio accessibility of (a) model starch solutions; (b) bread formulations. First, the model was compared with the rigorously mixed stirred tank reactor (STR). Then the effects of enzyme concentration/flow rate, starch concentration, and digesta viscosity (addition of guar gum) were evaluated.Compared to the STR, the SIM showed presence of lag phase when no digestive processes could be detected. The effects of enzyme concentration and flow rate appeared to be marginal in the region of mass transfer limited reactions. Addition of guar gum reduced simulated glucose absorption by up to 45 % in model starch solutions and by 35 % in bread formulations, indicating the importance of chyme rheology on nutrient bioaccessibility.Overall, the work highlights the significance of gut motility in digestive processes and offers a powerful tool in nutritional studies that, additionally to biochemical, considers engineering aspects of digestion. The potential to modulate food digestibility and nutrient bioaccessibility by altering food formulation is indicated.
Keywords: Starch digestion; Simulated glucose bioaccessibility; Intestinal motility; Dynamic in vitro models
Digestion-resistant maltodextrin effects on colonic transit time and stool weight: a randomized controlled clinical study by María Salud Abellán Ruiz; María Dolores Barnuevo Espinosa; Carlos J. Contreras Fernández; Antonio J. Luque Rubia; Francisca Sánchez Ayllón; Miriam Aldeguer García; Carlos García Santamaría; Francisco Javier López Román (2389-2397).
Increased awareness of the importance of dietary fibre has led to increased interest in “functional” fibre components like digestion-resistant maltodextrin (RMD). This randomized, placebo-controlled, double-blind study assessed the effects of RMD in the colonic transit time (CTT) and defecation characteristics (frequency, stool volume and consistency).Sixty-six healthy adult volunteers (32 men) who did not have a daily defecation habit had a 7-day run-in period before the 21-day intervention period with RMD or placebo. CTT and segmental CTT (SCTT) were assessed by a single abdominal X-ray film taken at the end of both periods after radiopaque marker ingestion. Defecation characteristics and intestinal functions were also assessed, which were self-reported by patients. Intragroup comparisons were evaluated by Student’s paired t test, Bonferroni test and Chi-square test, while time comparisons by analysis of variance (ANOVA) and time-by-treatment interaction by repeated-measures ANOVA.Fifty-seven subjects were assessed for CTT (placebo, n = 28; RMD, n = 29). In the RMD group, the total CTT, left SCTT and rectosigmoidal SCTT decreased significantly compared to baseline (p < 0.01 each; −13.3, −4.7, −8.7 h, respectively). Significant differences between groups were observed in total CTT and left SCTT. Significant time-by-treatment interaction was observed in the RMD group for stool volume (p = 0.014), increasing 56 % compared to baseline (p < 0.01), while remained unchanged in the placebo group. Stool consistency was improved only in the RMD group (p < 0.01). No adverse effects related to study products were observed.The results show that RMD improved CTT, stool volume, stool consistency and some intestinal functions in a healthy population.
Keywords: Colonic transit time; Resistant maltodextrin; Soluble dietary fibre; Stool volume; Intestinal function
Postnatal prebiotic fibre intake mitigates some detrimental metabolic outcomes of early overnutrition in rats by Danielle T. Reid; Lindsay K. Eller; Jodi E. Nettleton; Raylene A. Reimer (2399-2409).
Overnutrition during early development has been linked to metabolic disease and obesity in adulthood. Interventions to ameliorate this metabolic malprogramming are needed. Our objective was to determine whether prebiotic fibre would reduce weight gain and improve satiety hormone profiles in rats overnourished during the suckling period.Male Sprague–Dawley rats reared in small litter (SL 3 pups) or normal litter (NL 12 pups) were randomized at weaning to AIN-93 (control) or a 10 % oligofructose (OFS) diet for 16 weeks. Body composition, an oral glucose tolerance test for glucose and gut hormones, and gut microbiota were assessed.At weaning, body weight was higher in SL than in NL rats (P < 0.03). At 19 weeks, body weight was lower with OFS than control (P < 0.04). There was a diet × litter size interaction wherein OFS in SL rats reduced body fat (%) to levels seen in NL rats (P < 0.05). OFS attenuated the glucose response in SL but not in NL rats (P < 0.015). Independent of litter size, OFS decreased total AUC for glucose-dependent insulinotropic polypeptide (P < 0.002) and increased total AUC for peptide YY (P < 0.01) and glucagon-like peptide-1 (P < 0.04) when compared to control. OFS, not litter size, played the predominant role in altering gut microbiota which included increased bifidobacteria and Akkermansia muciniphila with OFS.Postnatal consumption of OFS by rats raised in SL was able to attenuate body fat and glycaemia to levels seen in NL rats. OFS appears to influence satiety hormone and gut microbiota response similarly in overnourished and control rats.
Keywords: Oligofructose; Postnatal overfeeding; Satiety hormones; Glycaemia; Gut microbiota
Increased risk of iron deficiency and reduced iron absorption but no difference in zinc, vitamin A or B-vitamin status in obese women in India by Isabelle Herter-Aeberli; Prashanth Thankachan; Beena Bose; Anura V. Kurpad (2411-2421).
Two objectives were investigated: (1) to assess the risk of micronutrient deficiencies in relation to weight status in Indian women with a focus on iron but also including zinc, vitamin A and B vitamins and (2) to compare fractional iron absorption between obese (OB) and normal weight (NW) women.Part 1 was a cross-sectional study including 146 healthy, middle-class women from Bangalore, India, with a BMI between 19 and 40 kg/m2. Anthropometrics and blood pressure were measured, and a fasting blood sample was obtained for the analysis of vitamin and mineral status, hepcidin, blood lipids and glucose. In part 2, 16 OB and 13 NW women consumed a standardized test meal labeled with the stable iron isotope 57Fe. Incorporation of the iron isotope into erythrocytes was measured 14 days later. In addition, iron status, hepcidin and inflammatory markers were determined.In part 1, compared to NW women, overweight/OB subjects had significantly higher C-reactive protein, serum ferritin, soluble transferrin receptor (sTfR) and hepcidin concentrations (p < 0.05). The odds ratio for having high sTfR concentrations (i.e., low iron status) with increasing BMI was 1.09 (95 % CI 1.02–1.17). None of the other micronutrients investigated showed any differences between weight status groups. In part 2, fractional iron absorption was significantly lower in the OB group compared to the NW group even after controlling for differences in iron status (10.0 ± 6.5 vs. 16.7 ± 4.6 %; p = 0.038).OB women in Bangalore have an increased risk of low iron status and absorb less dietary iron; however, their risk of other micronutrient deficiencies was similar to NW women. Our results clearly demonstrate the importance of considering the double burden of malnutrition in the planning of prevention strategies especially in transition countries with emerging obesity epidemics.
Keywords: Obesity; Iron deficiency; Iron absorption; Micronutrients; Hepcidin; Double burden
Betaine is as effective as folate at re-synthesizing methionine for protein synthesis during moderate methionine deficiency in piglets by Laura E. McBreairty; Jason L. Robinson; Scott V. Harding; Edward W. Randell; Janet A. Brunton; Robert F. Bertolo (2423-2430).
Both folate and betaine (synthesized from choline) are nutrients used to methylate homocysteine to reform the amino acid methionine following donation of its methyl group; however, it is unclear whether both remethylation pathways are of equal importance during the neonatal period when remethylation rates are high. Methionine is an indispensable amino acid that is in high demand in neonates not only for protein synthesis, but is also particularly important for transmethylation reactions, such as creatine and phosphatidylcholine synthesis. The objective of this study was to determine whether supplementation with folate, betaine, or a combination of both can equally re-synthesize methionine for protein synthesis when dietary methionine is limiting.Piglets were fed a low methionine diet devoid of folate, choline, and betaine, and on day 6, piglets were supplemented with either folate, betaine, or folate + betaine (n = 6 per treatment) until day 10. [1-13C]-phenylalanine oxidation was measured as an indicator of methionine availability for protein synthesis both before and after 2 days of supplementation.Prior to supplementation, piglets had lower concentrations of plasma folate, betaine, and choline compared to baseline with no change in homocysteine. Post-supplementation, phenylalanine oxidation levels were 20–46 % lower with any methyl donor supplementation (P = 0.006) with no difference among different supplementation groups. Furthermore, both methyl donors led to similarly lower concentrations of homocysteine following supplementation (P < 0.05).These data demonstrate an equal capacity for betaine and folate to remethylate methionine for protein synthesis, as indicated by lower phenylalanine oxidation.
Keywords: Piglet; Folate; Betaine; Protein synthesis; 1-Carbon metabolism
Isoliquiritigenin in licorice functions as a hepatic protectant by induction of antioxidant genes through extracellular signal-regulated kinase-mediated NF-E2-related factor-2 signaling pathway by Sang Mi Park; Jong Rok Lee; Sae Kwang Ku; Il Je Cho; Sung Hui Byun; Sang Chan Kim; Sook Jahr Park; Young Woo Kim (2431-2444).
Liver is the major site of biotransformation for exogenous toxins, in having a defense system against oxidative stress as well as cytochrome P450 system. Isoliquiritigenin (isoLQ) is an active component present in Glycyrrhizae radix and has been shown to have various biological activities. This study investigated the effect of isoLQ as a liver protectant against oxidative stress, both in vivo and in vitro, and also its molecular mechanisms.We used tert-butylhydroperoxide-induced hepatocyte damage model and cadmium (Cd)-stimulated liver toxicity animal model, which are assessed by immunoblot and flow cytometry as well as plasma and histopathological parameters.In HepG2 cells, pretreatment of 10 and 30 µM isoLQ significantly inhibited the induction of apoptosis and mitochondrial damage, and production of reactive oxygen species. Moreover, isoLQ induced the activation of nuclear factor erythroid 2-related factor-2 (Nrf2), as indicated by an increase in its nuclear translocation and antioxidant response element-luciferase activity. IsoLQ also induced the expression of Nrf2 target phase II enzymes, such as heme oxygenase-1, glutamate–cysteine ligase catalytic subunit and NAD(P)H:quinone oxidoreductase 1. IsoLQ also induced phosphorylation of extracellular stimuli-regulated kinase (ERK), and its activation of Nrf2 was mediated with ERK-dependent phosphorylation of Nrf2, as determined by its chemical inhibitor. In rats, oral treatment of 5 and 20 mg/kg isoLQ prevented Cd-induced acute hepatic damage, as assessed by plasma parameters and semiquantative histology, such as the modified HAI grading scores and the degenerative regions in hepatic parenchyma.These findings are considered as scientific evidence that isoLQ in licorice has the function of being a hepatic protectant against oxidative damages through ERK-mediated Nrf2 activation.
Keywords: Isoliquiritigenin; Liver protectant; Oxidative stress; Nrf2; ERK
Effect of a mixture of GOS/FOS® on calcium absorption and retention during recovery from protein malnutrition: experimental model in growing rats by Gabriel Bryk; Magalí Zeni Coronel; Carlos Lugones; Patricia Mandalunis; María Esther Rio; Ariel Felix Gualtieri; María Luz Pita Martín de Portela; Susana Noemí Zeni (2445-2458).
During growth, protein deprivation impairs epiphyseal growth plate (EGP) height, bone volume (BV) and endochondral ossification. During catch-up growth, Ca availability becomes essential to ensure the extra amount needed to achieve optimal peak bone mass and strength. GOS and FOS improve mineral absorption in the colon.The effect of a mixture of GOS/FOS® 9:1 added to a 0.5 %Ca (NCa) and a 0.3 %Ca (LCa) diets on Ca, P and Mg absorptions and bone mineralization, density and structure using an experimental model of growing rats recovering from early protein malnutrition was investigated.To induce protein malnutrition, rats were fed a low protein diet: 4 % (LPD) during 1 week and then were randomly assigned to recovery groups (R) until day 50 (T = 50) as follows: R0.5 %: NCa; RP0.5 %: NCa + 5.3 % GOS/FOS®; R0.3 %: LCa and RP0.3 %: LCa + 5.3 % GOS/FOS®. Control groups received the 0.5 %Ca or 0.3 %Ca diet from weaning until day 40 or 50.Body weight and length increased in C groups throughout the study; both were arrested in all R during LPD consumption and increased immediately after re-feeding. Independently of dietary Ca content, LS counts, β-glucosidase and Ca, P and Mg absorption increased, whereas cecum pH, β-glucuronidase, urease and tryptophanase decreased in RP0.5 %: and RP0.3 %: as compared to the other studied groups (p < 0.01). Prebiotic consumption decreased CTX levels and increased femur Ca, Mg and P contents, total skeleton bone mineral content, proximal tibia and spine BMD, BV, EGP height and hypertrophic zone thickness, stiffness and elastic modulus as compared to recovery groups fed the prebiotic-free diets.Under the present experimental conditions, GOS/FOS® mixture induced colonic positive effects, which increased Ca, P and Mg absorption. Thus, consuming the prebiotic-containing diet resulted in an extra amount of minerals that improved bone development in growing rats recovering from protein malnutrition.
Keywords: Calcium absorption; Calcium retention; Galacto-oligosaccharides; Fructo-oligosaccharides; Undernourished rats; Catch-up growth
Food intake and inflammation in European children: the IDEFICS study by Esther M. González-Gil; Javier Santabárbara; Paola Russo; Wolfgang Ahrens; Mandy Claessens; Lauren Lissner; Claudia Börnhorst; Vittorio Krogh; Licia Iacoviello; Denes Molnar; Alfonso Siani; Michael Tornaritis; Toomas Veidebaum; Luis A. Moreno (2459-2468).
This cross-sectional study assesses the relationship between consumption frequencies of food items and high-sensitivity C-reactive protein (hs-CRP) in European children. Out of the baseline sample (N = 16.228) of the IDEFICS study, 6.403 children (1.315 boys aged 2 to <6, 1.908 boys aged 6 to <10, 1.204 girls aged 2 to <6 and 1.976 girls aged 6 to <10 years) had hs-CRP measured and the Children’s Eating Habits Questionnaire filled, including a food frequency questionnaire. Logistic regression adjusted for body mass index z-score, education of the mother, breast-feeding and self-reported hours of physical activity in a sport club per week was conducted. Mean frequency intake of raw vegetable was lower in boys (p = 0.022 in young and p = 0.020 in old) and older girls (p = 0.026) with high hs-CRP concentration, while in younger girls (p = 0.008) the same occurred with the cooked vegetables. The probability of having higher hs-CRP concentration was significantly associated with having low consumption frequency of vegetables (p = 0.004 in older boys, raw vegetables; and p = 0.0032 in younger girls, cooked vegetables). Also, honey/jam intake decreased the probability of having higher concentration of hs-CRP, whereas soft drinks with sugar, mayonnaise and cereals milled increased this probability. Out of all food items associated with hs-CRP, frequency intake of vegetables presented more associations across all the analysis. Findings suggest that a high-frequency intake of vegetables is inversely related to an inflammatory status in children. More studies are needed to assess the association between diet and inflammation.
Keywords: Food intake; Inflammation; European; Children; IDEFICS
DNA damage and oxidative stress response to selenium yeast in the non-smoking individuals: a short-term supplementation trial with respect to GPX1 and SEPP1 polymorphism by E. Jablonska; S. Raimondi; J. Gromadzinska; E. Reszka; E. Wieczorek; M. B. Krol; A. Smok-Pieniazek; M. Nocun; M. Stepnik; K. Socha; M. H. Borawska; W. Wasowicz (2469-2484).
Selenium, both essential and toxic element, is considered to protect against cancer, though human supplementation trials have generated many inconsistent data. Genetic background may partially explain a great variability of the studies related to selenium and human health. The aim of this study was to assess whether functional polymorphisms within two selenoprotein-encoding genes modify the response to selenium at the level of oxidative stress, DNA damage, and mRNA expression, especially in the individuals with a relatively low selenium status.The trial involved 95 non-smoking individuals, stratified according to GPX1 rs1050450 and SEPP1 rs3877899 genotypes, and supplemented with selenium yeast (200 µg) for 6 weeks. Blood was collected at four time points, including 4 weeks of washout.After genotype stratification, the effect of GPX1 rs1050450 on lower GPx1 activity responsiveness was confirmed; however, in terms of DNA damage, we failed to indicate that individuals homozygous for variant allele may especially benefit from the increased selenium intake. Surprisingly, considering gene and time interaction, GPX1 polymorphism was observed to modify the level of DNA strand breaks during washout, showing a significant increase in GPX1 wild-type homozygotes. Regardless of the genotype, selenium supplementation was associated with a selectively suppressed selenoprotein mRNA expression and inconsistent changes in oxidative stress response, indicating for overlapped, antioxidant, and prooxidant effects. Intriguingly, DNA damage was not influenced by supplementation, but it was significantly increased during washout.These results point to an unclear relationship between selenium, genotype, and DNA damage.
Keywords: Selenium; Selenoproteins; Oxidative stress; DNA damage; Gene expression; Selenium supplementation
7-Keto-cholesterol and 25-hydroxy-1 cholesterol rapidly enhance ROS production in human neutrophils by Gonzalo Alba; María Edith Reyes-Quiróz; Javier Sáenz; Isabel Geniz; Juan Jiménez; José Martín-Nieto; Elizabeth Pintado; Francisco Sobrino; Consuelo Santa-María (2485-2492).
Oxysterols are cholesterol-oxygenated derivatives generated in the organism and also present in foods because of cholesterol oxidation during processing and storage. They are the natural ligands of liver X receptors (LXRs) and are generally recognized as hypocholesterolemic and anti-inflammatory molecules although this latter property is still controversial. Most oxysterol studies have been performed in macrophages, whereas the effects of oxysterols in neutrophils are poorly known. In this study, human neutrophils were exposed to two different oxysterols, 7-keto-cholesterol (7-k-chol) and 25-hydroxy-cholesterol (25-OH-chol), and their possible participation in inflammatory process was evaluated.Human neutrophils were incubated with 7-k-chol and 25-OH-chol, and ROS production, translocation of the NADPH oxidase cytosolic components, hemoxygenase-1 (HO-1) expression and lysozyme secretion were analyzed.An increase in ROS production was observed within a short period of time (minutes) with both molecules. These oxysterols also stimulated the cellular membrane translocation of the NADPH oxidase cytosolic components, p47phox and p67phox. On the other hand, HO-1 expression, a cytoprotector enzyme, is inhibited in human neutrophils upon oxysterols treatment. Moreover, both oxysterols were associated with high lysozyme enzyme secretion at 5 and 18 h of incubation.The present paper describes for the first time that two oxysterols (7-k-chol and 25-OH-chol) enhance the ROS production within a short period of time in human neutrophils, stimulate the translocation of the cytosolic components of NADPH oxidase to the cellular membrane and increase lysozyme secretion. These data suggest that both oxysterols are able to activate pro-inflammatory effects in human neutrophils which contrasts with the role assigned to the oxysterols when they act through LXR at long time of incubation.
Keywords: Oxysterols; Neutrophils; Radical oxygen species; Lipid metabolism; Hemoxygenase-1
Glycaemic responses to liquid food supplements among three Asian ethnic groups by Siew Ling Tey; Ardy Van Helvoort; Christiani Jeyakumar Henry (2493-2498).
A limited number of studies have compared the glycaemic index (GI) and glycaemic responses (GR) to solid foods between Caucasians and Asians. These studies have demonstrated that Asians have greater GI and GR values for solid foods than Caucasians. However, no study has compared the GI and GR to liquids among various Asian ethnic groups.A total of forty-eight males and females (16 Chinese, 16 Indians, and 16 Malay) took part in this randomised, crossover study. Glycaemic response to the reference food (glucose beverage) was measured on three occasions, and GR to three liquids were measured on one occasion each. Liquids with different macronutrient ratio’s and carbohydrate types were chosen to be able to evaluate the response to products with different GIs. Blood glucose concentrations were measured in duplicate at baseline (−5 and 0 min) and once at 15, 30, 45, 60, 90, and 120 min after the commencement of beverage consumption.There were statistically significant differences in GI and GR between the three liquids (P < 0.01 in all cases). However, there were no statistically significant differences in GI and GR for the liquids between the ethnic groups (Chinese vs. Indian vs. Malay).The GR for three different types of liquid nutritional supplements did not differ between the three main ethnic groups in Asia. It appears that the GI of liquid food derived from one Asian ethnicity can be applicable to other Asian populations.
Keywords: Glycaemic index; Glycaemic response; Liquid; Chinese; Indian; Malay