Effects of a Lutein and Zeaxanthin Intervention on Cognitive Function: A Randomized, Double-Masked, Placebo-Controlled Trial of Younger Healthy Adults.

Background: Past studies have suggested that higher lutein (L) and zeaxanthin (Z) levels in serum and in the central nervous system (as quantified by measuring macular pigment optical density, MPOD) are related to improved cognitive function in older adults. Very few studies have addressed the issue of xanthophylls and cognitive function in younger adults, and no controlled trials have been conducted to date to determine whether or not supplementation with L + Z can change cognitive function in this population. Objective: The purpose of this study was to determine whether or not supplementation with L + Z could improve cognitive function in young (age 18-30), healthy adults. Design: A randomized, double-masked, placebo-controlled trial design was used. Fifty-one young, healthy subjects were recruited as part of a larger study on xanthophylls and cognitive function. Subjects were randomized into active supplement (n = 37) and placebo groups (n = 14). MPOD was measured psychophysically using customized heterochromatic flicker photometry. Cognitive function was measured using the CNS Vital Signs testing platform. MPOD and cognitive function were measured every four months for a full year of supplementation. Results: Supplementation increased MPOD significantly over the course of the year, vs. placebo (p < 0.001). Daily supplementation with L + Z and increases in MPOD resulted in significant improvements in spatial memory (p < 0.04), reasoning ability (p < 0.05) and complex attention (p < 0.04), above and beyond improvements due to practice effects. Conclusions: Supplementation with L + Z improves CNS xanthophyll levels and cognitive function in young, healthy adults. Magnitudes of effects are similar to previous work reporting correlations between MPOD and cognition in other populations.

A unique combination of micronutrients rejuvenates cognitive performance in aged mice.

It is widely believed that diet can influence the onset and severity of cognitive aging, but the optimal combination of micronutrients and molecular and cellular mechanisms remain elusive. The purpose of this study was to compare the effects of eight distinct diets, consisting of various concentrations of selected micronutrients, on learning and memory as well as markers of neuronal plasticity, and metabolic and neuro-immune status of the aged hippocampus. Eighteen-month-old male and female C57BL/6J mice were fed the diets for 16 weeks, followed by learning and memory trials on the active avoidance task. Number of immature neurons were measured by immunohistochemical detection of doublecortin (DCX+) in the granule layer of the dentate gyrus. Amount of mitochondrial DNA (mtDNA) and gene expression of molecular markers of mitochondrial biogenesis (Ppargc1α, Sirt1, Tfam), and neuroinflammation (IL-10, Alox15, Ptgs2, IL-1ß, IL-6 and Tnf) were assessed by quantitative real time polymerase chain reaction (qRT-PCR) of hippocampal samples. Tissue levels of selected micronutrients and a number of metabolites were measured by liquid chromatography-mass spectrometry. The diet supplemented with RRR d-alpha tocopheryl acetate, citicholine, 5-methyltetrahydrofolic acid, quercetin and the n-3 fatty acid phosphatidylserine-docosahexaenoic acid, improved performance on the active avoidance learning and memory task compared to all the other less-complex diets. This diet also increased IL-10 expression and attenuated the age-related change in mtDNA content in the hippocampus without affecting metabolite levels. Results suggest cognitive benefits of wholesome diets are partially mediated through combined antioxidant and anti-inflammatory activities of optimized mixtures of micronutrients.

Long-lasting impairments in adult neurogenesis, spatial learning and memory from a standard chemotherapy regimen used to treat breast cancer.

The negative impact of chemotherapy on cognitive function in cancer patients has gained increasing attention in the last decade. Whilst the short-term acute effects on cognition are expected following chemotherapy, the persistence of such impairments in the long-term is still in question. This is despite clinical evidence indicating cognitive difficulties may persist well beyond treatment and affect quality of life. In the present study, we assessed the long-term (3 months) cognitive impact of chemotherapy in a mouse model intended to mimic the human female post-menopausal population receiving chemotherapy for breast cancer. Ovariectomized, female, C57BL/6J mice received two doses of Doxorubicin, Cyclophosphamide, and 5-Fluorouracil or saline vehicle (control), separated by one week. During this interval, mice received BrdU injections to label dividing cells. Results indicate a persistent impairment in learning and recall (1h, 24h and 48h) on the Morris water maze, reduced survival and differentiation of new neurons (BrdU+/NeuN+), and a persistent decline in proliferation of new cells (Ki67(+)) in the dentate gyrus. Locomotor activity, motor performance, and anxiety-like behavior were unaffected. We further evaluated the efficacy of a diet enriched in omega-3-fatty acids (DHA+EPA+DPA), in reversing long-term chemotherapy deficits but no rescue was observed. The model described produces long-term cognitive and cellular impairments from chemotherapy that mimic those observed in humans. It could be useful for identifying mechanisms of action and to test further the ability of lifestyle interventions (e.g., diet) for ameliorating chemotherapy-induced cognitive impairments.

Signaling pathways initiated by beta-hydroxy-beta-methylbutyrate to attenuate the depression of protein synthesis in skeletal muscle in response to cachectic stimuli.

To investigate the mechanism by which beta-hydroxy-beta-methylbutyrate (HMB) attenuates the depression of protein synthesis in the skeletal muscle of cachectic mice, a study has been carried out in murine myotubes in the presence of proteolysis-inducing factor (PIF). PIF inhibited protein synthesis by 50% within 4 h, and this was effectively attenuated by HMB (25-50 muM). HMB (50 muM) alone stimulated protein synthesis, and this was attenuated by rapamycin (27 nM), an inhibitor of mammalian target of rapamycin (mTOR). Further evidence for an involvement of this pathway was shown by an increased phosphorylation of mTOR, the 70-kDa ribosomal S6 kinase (p70(S6k)), and initiation factor 4E-binding protein (4E-BP1) and an increased association of eukaryotic initiation factor 2 (eIF4E) with eIF4G. PIF alone induced a transient (1-2 h) stimulation of phosphorylation of mTOR and p70(S6k). However, in the presence of HMB, phosphorylation of mTOR, p70(S6k), and 4E-BP1 was increased, and inactive 4E-BP1-eIF4E complex was reduced, whereas the active eIF4G.eIF4E complex was increased, suggesting continual stimulation of protein synthesis. HMB alone reduced phosphorylation of elongation factor 2, but this effect was not seen in the presence of PIF. PIF induced autophosphorylation of the double-strand RNA-dependent protein kinase (PKR), leading to phosphorylation of eIF2 on the alpha-subunit, which would inhibit protein synthesis. However, in the presence of HMB, phosphorylation of PKR and eIF2alpha was attenuated, and this was also observed in skeletal muscle of cachectic mice administered HMB (0.25 g/kg). These results suggest that HMB attenuates the depression of protein synthesis by PIF in myotubes through multiple mechanisms.

Direct determination of methionine sulfoxide in milk proteins by enzyme hydrolysis/high-performance liquid chromatography.

A direct and simultaneous HPLC/UV determination of methionine and methionine sulfoxide in enzyme-hydrolyzed milk proteins is described. Protein hydrolysis is accomplished by a three-enzyme (pronase, leucine aminopeptidase, prolidase) 20-h/37 degrees C digestion. A gradient elution reversed-phase HPLC system with UV detection at 214 nm and 280 nm is then used to determine the quantitative releases of methionine sulfoxide, methionine, tyrosine, and tryptophan. The ease of methionine oxidation by a wide variety of oxidants, coupled with the quantitative release of both methionine and its sulfoxide by the three-enzyme hydrolysis, renders the approach valuable for identifying oxidized milk proteins. The relatively simple method proved accurate and precise in its application to commercial milk products, finding methionine sulfoxide levels as high as 74% of the total methionine.

N-acetyl-L-glutamine, a liquid-stable source of glutamine, partially prevents changes in body weight and on intestinal immunity induced by protein energy malnutrition in pigs.

The goal of this study was to evaluate the preventive effect of free glutamine versus N-acetyl-L-glutamine, a liquid-stable source of glutamine, on gut damage induced by protein energy malnutrition in pigs. Healthy pigs (n = 6) were fed a liquid formula for 30 days. Three subgroups of malnourished pigs (n = 6) received daily 20% of the food intake recorded in control group, supplemented with calcium caseinate, glutamine, or N-acetyl-L-glutamine. Body weight was recorded, and small intestinal samples were evaluated for biochemical and immunologic parameters. Suppression in body weight gain was significantly lower in pigs fed with N-acetyl-L-glutamine than in the rest of malnourished pigs. Total number of lymphocytes, CD21+ B cells and CD4+ T cells in ileal Peyer patches were not significantly different in malnourished pigs fed with N-acetyl-L-glutamine and in healthy pigs. In conclusion, N-acetyl-L-glutamine has a moderate protective effect, partially preventing changes induced by protein energy malnutrition.

Glutamine in commercial liquid nutritional products.

Total glutamine concentrations in commercial nutritional products have been determined by enzymatic hydrolysis followed by HPLC quantification of free glutamine and free pyroglutamic acid. Hydrolysis was accomplished by a published three-enzyme (Pronase, leucine aminopeptidase, prolidase), 20-h/37 degrees C digestion. Glutamine was determined as its FMOC derivative by reverse phase HPLC-fluorescence, and pyroglutamic acid was determined directly by organic acid HPLC-UV. Approximately 4.11% of the released glutamine is converted to pyroglutamic acid during the 20-h digestion. Experimental ratios of enzyme hydrolysis glutamine to acid hydrolysis glutamic acid + glutamine + pyroglutamic acid (GLX) indicate that the method recovers >90% of the protein-bound glutamine. The nutritional products with casein dominant intact protein systems typically deliver >9 g of glutamine/100 g of protein, or approximately 40 g of glutamine/100 g of GLX.

Characterization of high-salt and high-fat diets on cardiac and vascular function in mice.

This study compared two established dietary formulations, high salt and high fat-high carbohydrate, separately or in combination on the induction cardiovascular dysfunction. One-month-old C57BL/6J mice were fed one of the following diets for 3 mo: (1) control diet consisting of a high fat-high sim-ple carbohydrate (HFHSC); (2) 8% NaCl diet (HS); or (3) HFHSC diet supplemented with 1% NaCl (HFHS). After 3 mo, the HFHSC mice demonstrated significantly increased end-diastolic volume and end-systolic volume, specifically increases of 35% and 78%, respectively (p < 0.01) and a reduction of ventricular stiffness by 27% (p = 0.015). The HS mice exhibited arterial hyper-tension with an increase of 33% in maximum end-systolic pressure (p =.024) and a decrease of 44% in arterial elastance (p = 0.020), corroborated by an increase in the heart weight to body weight ratios (p = 0.002) and vascular types I and III collagen (p = 0.03 and p = 0.0008, respectively). The HFHS group revealed a striking response of 230% to the alpha1-adrenergic challenge (p = 0.00034). These data suggest that the HFHSC diet causes dilated cardio-myopathy, whereas the HS diet produces arterial hypertension and the HFHS diet causes a vascular dysfunctional state that was highly responsive to alpha-adrenergic stimulation.

Yeast extract stimulates glucose metabolism and inhibits lipolysis in rat adipocytes in vitro.

Foods contain bioactive components that contribute to optimal health. Food-grade yeast may contain components that enhance cellular glucose metabolism. We tested the effect of brewer's yeast (Saccharomyces cerevisiae) extract (YE), in vitro on rat fat cell glucose transport, glucose metabolism to lipid, and lipolysis. YE was fractionated by reverse-phase chromatography on a C18 open column using ammonium acetate (0.05 mol/L, pH 5.8), with acetonitrile (40%) elution solvent into fraction 1 (Fx1), fraction 2 (Fx2) and fraction 3 (Fx3). Isolated rat adipocytes were preincubated with insulin (51 pmol/L), YE (10 mg/L) or both; transport of U-(14)C-glucose was measured. Adipocytes were incubated with insulin and YE fractions (10 mg/L); glucose metabolism to lipid was measured by incorporation of U-(14)C-glucose into total lipids. Lipolysis was measured by glycerol release. Insulin stimulated glucose transport to sevenfold the basal value (P < 0.05). YE did not affect glucose transport. Insulin stimulated glucose metabolism to 2.6-fold the basal value (P < 0.001); YE stimulated glucose metabolism 14% (P < 0.005). YE potentiated the action of insulin 30% (P < 0.002). YE Fx2 and Fx3 stimulated glucose metabolism 25-40% (P < 0.05). Insulin inhibited lipolysis 47% (P < 0.001). YE alone inhibited lipolysis 63% (P < 0.001). YE and insulin inhibited lipolysis 81% (P < 0.001). Fractions of YE inhibited lipolysis in the presence of insulin (P < 0.05); the order of potency was Fx2 = Fx3 >> Fx1. A novel yeast extract (YE) and its fractions affect pathways of adipocyte metabolism differentially. YE and its fractions are good candidates for in vivo study.