Cocoa Flavanol Supplementation and the Effect on Insulin Resistance in Females Who Are Overweight or Obese: A Randomized, Placebo-Controlled Trial.

There is interest in the impact that dietary interventions can have on preventing the transition from insulin resistance to type 2 diabetes, including a suggestion that the bioactive components of cocoa may enhance fasting insulin sensitivity. However, a role for cocoa flavanols (CF) in reducing insulin resistance in the insulin-stimulated state, an important risk factor for cardiovascular disease, is unresolved. This study investigated whether CF consumption improved whole-body insulin-mediated glucose uptake ('M') in females with overweight/obesity, using a randomized, double-blinded, placebo-controlled, parallel-group design. Thirty-two premenopausal females (19-49 years; 27-35 kg·m-2) with elevated HOMA-IR (HOMA-IR >1.5) supplemented their habitual diet with two servings/day of a high-flavanol cocoa drink (HFC; 609 mg CF/serving; n = 16) or low-flavanol cocoa drink (LFC; 13 mg CF/serving; n = 16) for 4 weeks. Assessment of HOMA-IR and 'M' during a 3-h, 60 mIU insulin·m-2·min-1 euglycemic clamp was performed before and after the intervention. Data are the mean (SD). Changes to HOMA-IR (HFC -0.003 (0.57); LFC -0.0402 (0.86)) and 'M' (HFC 0.99 (7.62); LFC -1.32 (4.88) µmol·kg-1·min-1) after the intervention were not different between groups. Four weeks' consumption of ~1.2 g CF/day did not improve indices of fasting insulin sensitivity or insulin-mediated glucose uptake. A recommendation for dietary supplementation with cocoa flavanols to improve glycemic control is therefore not established.

Hypoglycemic thalamic activation in type 1 diabetes is associated with preserved symptoms despite reduced epinephrine.

Brain responses to low plasma glucose may be key to understanding the behaviors that prevent severe hypoglycemia in type 1 diabetes. This study investigated the impact of long duration, hypoglycemia aware type 1 diabetes on cerebral blood flow responses to hypoglycemia. Three-dimensional pseudo-continuous arterial spin labeling magnetic resonance imaging was performed in 15 individuals with type 1 diabetes and 15 non-diabetic controls during a two-step hyperinsulinemic glucose clamp. Symptom, hormone, global cerebral blood flow and regional cerebral blood flow responses to hypoglycemia were measured. Epinephrine release during hypoglycemia was attenuated in type 1 diabetes, but symptom score rose comparably in both groups. A rise in global cerebral blood flow did not differ between groups. Regional cerebral blood flow increased in the thalamus and fell in the hippocampus and temporal cortex in both groups. Type 1 diabetes demonstrated lesser anterior cingulate cortex activation; however, this difference did not survive correction for multiple comparisons. Thalamic cerebral blood flow change correlated with autonomic symptoms, and anterior cingulate cortex cerebral blood flow change correlated with epinephrine response across groups. The thalamus may thus be involved in symptom responses to hypoglycemia, independent of epinephrine action, while anterior cingulate cortex activation may be linked to counterregulation. Activation of these regions may have a role in hypoglycemia awareness and avoidance of problematic hypoglycemia.

Deferiprone: Pan-selective Histone Lysine Demethylase Inhibition Activity and Structure Activity Relationship Study.

Deferiprone (DFP) is a hydroxypyridinone-derived iron chelator currently in clinical use for iron chelation therapy. DFP has also been known to elicit antiproliferative activities, yet the mechanism of this effect has remained elusive. We herein report that DFP chelates the Fe2+ ion at the active sites of selected iron-dependent histone lysine demethylases (KDMs), resulting in pan inhibition of a subfamily of KDMs. Specifically, DFP inhibits the demethylase activities of six KDMs - 2A, 2B, 5C, 6A, 7A and 7B - with low micromolar IC50s while considerably less active or inactive against eleven KDMs - 1A, 3A, 3B, 4A-E, 5A, 5B and 6B. The KDM that is most sensitive to DFP, KDM6A, has an IC50 that is between 7- and 70-fold lower than the iron binding equivalence concentrations at which DFP inhibits ribonucleotide reductase (RNR) activities and/or reduces the labile intracellular zinc ion pool. In breast cancer cell lines, DFP potently inhibits the demethylation of H3K4me3 and H3K27me3, two chromatin posttranslational marks that are subject to removal by several KDM subfamilies which are inhibited by DFP in cell-free assay. These data strongly suggest that DFP derives its anti-proliferative activity largely from the inhibition of a sub-set of KDMs. The docked poses adopted by DFP at the KDM active sites enabled identification of new DFP-based KDM inhibitors which are more cytotoxic to cancer cell lines. We also found that a cohort of these agents inhibited HP1-mediated gene silencing and one lead compound potently inhibited breast tumor growth in murine xenograft models. Overall, this study identified a new chemical scaffold capable of inhibiting KDM enzymes, globally changing histone modification profiles, and with specific anti-tumor activities.

Vitamin intake is associated with improved visuospatial and verbal semantic memory in middle-aged individuals.

OBJECTIVES: Factors maintaining cognitive health are still largely unknown. In particular, the cognitive benefits associated with vitamin intake and vitamin supplementation are disputed. We investigated self-reported vitamin intake and serum vitamin levels with performance in cognitive factors sensitive to dementia progression in two large middle-aged general population cohorts. METHODS: Survey data were used to assess regular vitamin intake in 4400 NCDS 1958 and 1177 TwinsUK cohort members, and serum homocysteine and B vitamin levels were measured in 675 individuals from the TwinsUK study. Principal component analysis was applied to cognitive test performance from both cohorts resulting in two dementia-sensitive cognitive factors reflecting visuospatial associative memory and verbal semantic memory. RESULTS: In both cohorts, individuals who reported regular intake of vitamins, particularly B vitamins, showed significantly better performance in visuospatial associative memory and verbal semantic memory (P < 0.001). A significant association was also found between homocysteine levels, vitamin serum concentration and visuospatial associative memory performance which indicated that individuals with high B vitamin and homocysteine levels showed better visuospatial associative memory performance than individuals with low vitamin B levels (P < 0.05). DISCUSSION: The findings demonstrate that early dementia-sensitive cognitive changes can be identified in middle-aged asymptomatic individuals and that regular vitamin intake is associated with improved cognitive performance. These findings reinforce the potential cognitive benefits of regular vitamin intake, which should be considered as an economically viable therapeutic strategy for maintaining cognitive health.

Acute pantothenic acid and cysteine supplementation does not affect muscle coenzyme A content, fuel selection, or exercise performance in healthy humans.

Reduced skeletal muscle free coenzyme A (CoASH) availability may decrease the contribution of fat oxidation to ATP production during high-intensity, submaximal exercise or, alternatively, limit pyruvate dehydrogenase complex (PDC) flux and thereby carbohydrate oxidation. Here we attempted to increase the muscle CoASH pool in humans, via pantothenic acid and cysteine feeding, in order to elucidate the role of CoASH availability on muscle fuel metabolism during exercise. On three occasions, eight healthy male volunteers (age 22.9 ± 1.4 yr, body mass index 24.2 ± 1.5 kg/m(2)) cycled at 75% maximal oxygen uptake (Vo(2max)) to exhaustion, followed by a 15-min work output performance test. Muscle biopsies were obtained at rest, and after 60 min and 91.3 ± 3.1 min of exercise (time to exhaustion on baseline visit) on each occasion. Two weeks following the first visit (baseline), 1 wk of oral supplementation with either 3 g/day of a placebo control (glucose polymer; CON) or 1.5 g/day each of d-pantothenic acid and l-cysteine (CP) was carried out prior to the second and third visits in a randomized, counterbalanced, double-blind manner, leaving a 3-wk gap in total between each visit. Resting muscle CoASH content was not altered by supplementation in any visit. Following 60 min of exercise, muscle CoASH content was reduced by 13% from rest in all three visits (P < 0.05), and similar changes in the respiratory exchange ratio, glycogenolysis (∼235 mmol/kg dry muscle), PCr degradation (∼57 mmol/kg dry muscle), and lactate (∼25 mmol/kg dry muscle) and acetylcarnitine (∼12 mmol(.)kg/dry muscle) accumulation was observed during exercise when comparing visits. Furthermore, no difference in work output was observed when comparing CON and CP. Acute feeding with pantothenic acid and cysteine does not alter muscle CoASH content and consequently does not impact on muscle fuel metabolism or performance during exercise in humans.

Chronic oral ingestion of L-carnitine and carbohydrate increases muscle carnitine content and alters muscle fuel metabolism during exercise in humans.

We have previously shown that insulin increases muscle total carnitine (TC) content during acute i.v. l-carnitine infusion. Here we determined the effects of chronic l-carnitine and carbohydrate (CHO; to elevate serum insulin) ingestion on muscle TC content and exercise metabolism and performance in humans. On three visits, each separated by 12 weeks, 14 healthy male volunteers (age 25.9 ± 2.1 years, BMI 23.0 ± 0.8 kg m−2) performed an exercise test comprising 30 min cycling at 50% , 30 min at 80% , then a 30 min work output performance trial. Muscle biopsies were obtained at rest and after exercise at 50% and 80% on each occasion. Following visit one, volunteers ingested either 80 g of CHO (Control) or 2 g of l-carnitine-l-tartrate and 80 g of CHO (Carnitine) twice daily for 24 weeks in a randomised, double blind manner. All significant effects reported occurred after 24 weeks. Muscle TC increased from basal by 21% in Carnitine (P < 0.05), and was unchanged in Control. At 50% , the Carnitine group utilised 55% less muscle glycogen compared to Control (P < 0.05) and 31% less pyruvate dehydrogenase complex (PDC) activation compared to before supplementation (P < 0.05). Conversely, at 80% , muscle PDC activation was 38% higher (P < 0.05), acetylcarnitine content showed a trend to be 16% greater (P < 0.10), muscle lactate content was 44% lower (P < 0.05) and the muscle PCr/ATP ratio was better maintained (P < 0.05) in Carnitine compared to Control. The Carnitine group increased work output 11% from baseline in the performance trial, while Control showed no change. This is the first demonstration that human muscle TC can be increased by dietary means and results in muscle glycogen sparing during low intensity exercise (consistent with an increase in lipid utilisation) and a better matching of glycolytic, PDC and mitochondrial flux during high intensity exercise, thereby reducing muscle anaerobic ATP production. Furthermore, these changes were associated with an improvement in exercise performance.

A randomized cross-over study of the metabolic and hormonal responses following two preoperative conditioning drinks.

OBJECTIVE: Preoperative conditioning with carbohydrate-based drinks attenuates postoperative insulin resistance and leads to clinical benefits. The use of metabolic conditioning agents such as glutamine and antioxidants, in addition to carbohydrate, may benefit patients undergoing major surgery, because glutamine and antioxidant supplementation have been shown to improve gastrointestinal perfusion, immune function, morbidity, and gluco-metabolic control in critically ill patients. We investigated the postprandial responses after ingestion of a clear carbohydrate drink (CCD) containing 50 g of carbohydrate (preOp, Nutricia, Trowbridge, UK) and that of another drink containing 50 g of carbohydrate, 15 g of glutamine, and antioxidants (ONS; Fresenius Kabi, Bad Homburg, Germany). METHODS: Twelve overnight-fasted healthy male subjects ingested one of the drinks in a randomized, double-blinded, cross-over manner, after which blood was sampled for 360 min for measurement of glucose, insulin, glucagon, non-esterified fatty acids, ß-hydroxybutyrate and glutamine. RESULTS: The means ± standard errors for age and body mass index of participants were 21 ± 0.9 y and 23.2 ± 0.5 kg/m(2). After CCD ingestion, glucose and insulin concentrations peaked within 40 min (8.4 ± 0.4 mmol/L and 43.9 ± 3.8 mIU/L, respectively) and returned to baseline at 80 min (glucose 4.9 ± 0.3 mmol/L) and 140 min (insulin 5.5 ± 0.5 mIU/L). After ONS ingestion, peak glucose and insulin concentrations occurred within 40 min but were of a lower magnitude (6.6 ± 0.1 mmol/L and 29.6 ± 2.9 mIU/L, respectively). Glucose concentrations after ONS were higher than after CCD at 100 min. CONCLUSION: Peak insulin and glucose concentrations were higher after CCD ingestion; in contrast, responses after ONS ingestion were "blunted" and prolonged.

A randomized crossover study of the effects of glutamine and lipid on the gastric emptying time of a preoperative carbohydrate drink.

BACKGROUND & AIMS: Supplementing preoperative carbohydrate drinks with glutamine may lead to benefits in addition to reducing insulin resistance, but amino acids may delay gastric emptying (GE). The effects of supplementing a preoperative carbohydrate drink (CCD) with glutamine or lipid on GE were studied. METHODS: Ten healthy male volunteers ingested 410 ml of one of three isocaloric-isovolumetric carbohydrate-based drinks labelled with (99m)Tc-DTPA: CCD (preOp(®), Nutricia, UK, 50 g carbohydrate), CCD/G (preOp(®), 36 g carbohydrate + 15 g glutamine) or CCD/L (preOp(®), 36 g carbohydrate + 7 g lipid) in this randomized, blinded, three-way crossover study. After baseline measurements, GE was measured scintigraphically and blood sampled for insulin, glucose and glucagon-like peptide 1 (GLP-1) at 20 min intervals for 240 min. RESULTS: Mean (95% CI) T(90) GE times for CCD, CCD/G and CCD/L were 101 (87-115), 95 (84-107) and 87 (72-102) min, respectively. At 40 min postprandially, mean (SEM) concentrations of glucose (mmol/l) and insulin (mIU/l) were 7.5 (0.5) and 35 (5) for CCD; 6.2 (0.2) and 28 (4) for CCD/G; and 7 (0.3) and 31 (5) for CCD/L, respectively. There were no differences in postprandial GLP-1 concentrations. CONCLUSIONS: Glutamine and lipid supplementation did not prolong the GE of CCD but did 'blunt' postprandial glucose and insulin responses, independent of GLP-1 concentrations. Registered under ClinicalTrials.gov Identifier no. NCT00943020.

Dose-response effect of a whey protein preload on within-day energy intake in lean subjects.

The effect of consuming different amounts of whey protein on appetite and energy intake was investigated in two separate studies using randomised, crossover designs. Healthy-weight men and women (range: BMI 19·0-25·0 kg/m², age 19·4-40·4 years) consumed one of four 400 ml liquid preloads, followed by an ad libitum test meal 90 min later. In study 1, preloads were 1675 kJ with 12·5, 25 or 50 % of energy from protein, and in study 2, preloads were 1047 kJ with 10, 20 or 40 % energy from protein. Flavoured water was used as the control in both the studies. Appetite ratings were collected immediately before 30, 60 and 90 min after consuming the preloads; and immediately, 30 and 60 min after consuming the test meal. In study 1, energy intake following the control preload (4136 ((SEM) 337) kJ) was significantly higher than each of the 12·5 % (3520 ((SEM) 296) kJ), 25 % (3384 ((SEM) 265) kJ) and 50 % (2853 ((SEM) 244) kJ) protein preloads (P < 0·05). Intake after the 12·5 % preload was significantly higher than following 25 and 50 % preloads (P < 0·05). In study 2, energy intake following the control preload (4801 ((SEM) 325) kJ) was higher than following the 10 % (4205 ((SEM) 310) kJ), 20 % (3988 ((SEM) 250) kJ) and 40 % (3801 ((SEM) 245) kJ) protein preloads (P < 0·05). There were no differences in subjective appetite ratings between preloads in either study. These findings indicate a dose-response effect of protein content of the preload on energy intake at a subsequent meal.

Cellular mechanisms underlying the protective effects of preoperative feeding: a randomized study investigating muscle and liver glycogen content, mitochondrial function, gene and protein expression.

OBJECTIVE: To investigate the effects of preoperative feeding with a carbohydrate-based drink that also contained glutamine and antioxidants (oral nutritional supplement [ONS], Fresenuis Kabi, Germany) on glycogen reserves, mitochondrial function, and the expression of key metabolic genes and proteins. SUMMARY BACKGROUND DATA: Preoperative carbohydrate loading attenuates the decline in postoperative insulin sensitivity but the cellular mechanisms underlying this remain unclear. METHODS: Two groups of 20 patients undergoing laparoscopic cholecystectomy participated in this randomized placebo-controlled double-blind study. Patients received either 600 mL of ONS or placebo the evening before surgery, and again 300 mL 3 to 4 hours before anesthesia. A 300-mL aliquot of ONS contained 50 g of carbohydrate, 15 g of glutamine and antioxidants. Blood was sampled before ingestion of the evening drink, after induction of anesthesia, and on postoperative day 1 for measurement of concentrations of glucose, glutamine, and antioxidants. Rectus abdominis muscle and liver biopsies were performed intraoperatively to determine glycogen and glutamine concentrations, mitochondrial function, pyruvate dehydrogenase kinase (PDK4), forkhead transcription factor 1 (FOXO1), and metallothionein 1A (Mt1A) expression. RESULTS: There were no drink-related complications. ONS ingestion led to increased intraoperative liver glycogen reserves (44%, P < 0.001) and plasma glutamine and antioxidant concentrations, the latter 2 remaining elevated up to the first postoperative day. Muscle PDK4 mRNA, PDK4 protein expression, and Mt1A mRNA expression were 4-fold (P < 0.001), 44% (P < 0.05), and 1.5-fold (P < 0.001), respectively, lower in the ONS group. There were no differences in FOXO1 mRNA and protein expression. CONCLUSIONS: The changes in muscle PDK4 may explain the mechanism by which preoperative feeding with carbohydrate-based drinks attenuates the development of postoperative insulin resistance.

The effects of fasting and refeeding with a 'metabolic preconditioning' drink on substrate reserves and mononuclear cell mitochondrial function.

BACKGROUND AND AIMS: Preoperative fasting induces metabolic stress and leads to reduced postoperative insulin sensitivity, changes attenuated by preoperative carbohydrate loading. However, the mechanisms underlying these effects remain unknown. We investigated the dynamic changes in substrate metabolism and mononuclear cell mitochondrial function after fasting followed by refeeding with a drink [ONS (Fresenius Kabi, Germany)] designed to improve metabolic function preoperatively. METHODS: Twelve healthy volunteers took part in this study. They were fed a standardized meal and studied 4h later (baseline 'fed' state), after 12 and 24h of fasting, and 2, 4 and 6h after ingestion of ONS (contained 100g carbohydrate, 30g glutamine, and antioxidants). Changes in liver and muscle glycogen and lipids were studied using (13)C and (1)H magnetic resonance spectroscopy. The activities of mitochondrial electron transport chain complexes I, II and IV in blood mononuclear cells were measured spectrophotometrically. RESULTS: Compared to the baseline fed state, 12 and 24h fasts led to 29% and 57% decreases (P<0.001) in liver glycogen content, respectively. Fasting for 24h decreased mitochondrial membrane complexes I (-72%, P<0.05), II (-49%, P<0.01) and IV (-41%, P<0.05) activities compared to those following a 12h fast. A 23% increase (P<0.05) in calf intramyocellular lipid (IMCL) content occurred after a 24h fast. Liver glycogen reserves increased by 47% (P<0.05) by 2h following ingestion of ONS. CONCLUSIONS: Short-term fasting (up to 24h) affected mononuclear cell mitochondrial function adversely and increased IMCL content. Refeeding with ONS partially reversed the changes in liver glycogen.

Optimising nutrition in chronic renal insufficiency--growth.

The need to optimise nutrition to promote growth in infants with chronic renal insufficiency (CRI) is well recognised, but there is less enthusiasm for such an approach in older children and those with milder degrees of CRI. Energy intakes and growth outcomes were prospectively monitored over a 2-year period in children aged 2-16 years with differing levels of severity of CRI, as part of their ongoing joint medical/ dietetic care. Children were grouped following [(51)Cr]-labelled EDTA glomerular filtration rate (GFR, ml/min per 1.73 m(2)) estimations, into 'normal' kidney function [GFR >75, mean 106 (SD 19.5), n =58], providing baseline data only, mild (GFR 51-75, n =25), moderate (GFR 25-50, n =21), and severe (GFR <25, n=19) CRI. Children were followed for 2 years, with 51 completing the study (19 mild, 19 moderate, 13 severe CRI), and were excluded if they required dialysis. None received growth hormone. Regular dietary advice was provided and yearly 3-day semi-quantitative dietary diaries and baseline and 6-monthly anthropometric measurements were obtained. Mean height standard deviation score (SDS) was maintained in those with mild and moderate CRI and significantly increased in children with severe CRI [0.1 SDS (0.32 SD), F =9.45, 1 df, P =0.003]. There was a non-significant reduction in energy intake from dietary records overall (median -8.5% estimated average requirement), associated with poor adherence to supplements in severe CRI and under-reporting in the mild group. An increase in height or body mass index SDS, however, was observed in all children who took the supplements as prescribed. A correlation between change in energy intake and change in height SDS was observed in severe CRI ( r(2)=0.58, P =0.011). Regular dietetic advice, with particular attention to adherence to optimise energy intake, may improve growth, irrespective of age and should form an integral part of the clinical care package.

Optimising nutrition in chronic renal insufficiency--progression of disease.

There is a lack of evidence to support the belief that dietary measures are beneficial in slowing the progression of chronic renal insufficiency (CRI). We prospectively monitored nutrient intakes and progression of CRI over a 2-year period in children aged 2-16 years with differing levels of severity of CRI, as part of their ongoing joint medical/dietetic care. Children were grouped following [5'Cr]-labelled EDTA glomerular filtration rate(GFR, ml/min per 1.73 m 2) estimations, into 'normal'kidney function [GFR >75, mean 106 (SD 19.5), n=58],providing baseline data only, mild (GFR 51-75, n=25),moderate (GFR 25-50, n =21), and severe (GFR <25, n=19) CRI. Children with CRI were followed for 2 years,with 51 completing the study (19 mild, 19 moderate, 13 severe CRI) and were excluded if they subsequently required dialysis. Regular medical and dietary advice was provided and yearly 3-day semi-quantitative dietary di-aries and baseline and 6-monthly measurements of blood pressure and urinary protein/creatinine ratio were obtained. Mean reductions in estimated GFR over 2 years were -9.4, -5.8, and -6.0 ml/min per 1.73 m2 for mild,moderate, and severe CRI, respectively. Mean systolic blood pressure standard deviation score (SDS) fell significantly in all groups by 0.7 SDS, whereas there was little change in proteinuria. From reported dietary intakes,median sodium intakes increased (+10 mmol/day) and protein intakes decreased (-0.4 g/kg per day). Median phosphate intakes did not change significantly, where as calcium intakes fell in all groups, with an overall median of -20% reference nutrient intake (RNI) (F=33.3,P<0.001). Of children with moderate CRI, 65% finished with calcium intakes below 80% RNI, and parathyroid hormone (PTH) concentrations significantly increased in this group (F=6.0, P=0.021). Higher phosphate and sodium intakes were associated with greater deterioration in estimated GFR in children with mild CRI (r2=0.30,P=0.02; r-=0.31, P=0.02, respectively). There was no such correlation for protein intake or PTH. This study emphasises the need for a joint medical and dietetic approach and indicates a number of interventions other than protein restriction, which could be commenced early in children with CRI in an attempt to delay progression.