Cardiovascular Effects of Oral Ketone Ester Treatment in Patients With Heart Failure With Reduced Ejection Fraction: A Randomized, Controlled, Double-Blind Trial.

BACKGROUND: Heart failure triggers a shift in myocardial metabolic substrate utilization, favoring the ketone body 3-hydroxybutyrate as energy source. We hypothesized that 14-day treatment with ketone ester (KE) would improve resting and exercise hemodynamics and exercise capacity in patients with heart failure with reduced ejection fraction. METHODS: In a randomized, double-blind cross-over study, nondiabetic patients with heart failure with reduced ejection fraction received 14-day KE and 14-day isocaloric non-KE comparator regimens of 4 daily doses separated by a 14-day washout period. After each treatment period, participants underwent right heart catheterization, echocardiography, and blood sampling at plasma trough levels and after dosing. Participants underwent an exercise hemodynamic assessment after a second dosing. The primary end point was resting cardiac output (CO). Secondary end points included resting and exercise pulmonary capillary wedge pressure and peak exercise CO and metabolic equivalents. RESULTS: We included 24 patients with heart failure with reduced ejection fraction (17 men; 65±9 years of age; all White). Resting CO at trough levels was higher after KE compared with isocaloric comparator (5.2±1.1 L/min versus 5.0±1.1 L/min; difference, 0.3 L/min [95% CI, 0.1-0.5), and pulmonary capillary wedge pressure was lower (8±3 mm Hg versus 11±3 mm Hg; difference, -2 mm Hg [95% CI, -4 to -1]). These changes were amplified after KE dosing. Across all exercise intensities, KE treatment was associated with lower mean exercise pulmonary capillary wedge pressure (-3 mm Hg [95% CI, -5 to -1] ) and higher mean CO (0.5 L/min [95% CI, 0.1-0.8]), significantly different at low to moderate steady-state exercise but not at peak. Metabolic equivalents remained similar between treatments. In exploratory analyses, KE treatment was associated with 18% lower NT-proBNP (N-terminal pro-B-type natriuretic peptide; difference, -98 ng/L [95% CI, -185 to -23]), higher left ventricular ejection fraction (37±5 versus 34±5%; P=0.01), and lower left atrial and ventricular volumes. CONCLUSIONS: KE treatment for 14 days was associated with higher CO at rest and lower filling pressures, cardiac volumes, and NT-proBNP levels compared with isocaloric comparator. These changes persisted during exercise and were achieved on top of optimal medical therapy. Sustained modulation of circulating ketone bodies is a potential treatment principle in patients with heart failure with reduced ejection fraction. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT05161650.

Effects of exogenous lactate on lipid, protein, and glucose metabolism-a randomized crossover trial in healthy males.

Lactate may inhibit lipolysis and thus enhance insulin sensitivity, but there is a lack of metabolic human studies. This study aimed to determine how hyperlactatemia affects lipolysis, glucose- and protein metabolism, and insulin sensitivity in healthy men. In a single-blind, randomized, crossover design, eight healthy men were studied after an overnight fast on two occasions: 1) during a sodium-lactate infusion (LAC) and 2) during a sodium-matched NaCl infusion (CTR). Both days consisted of a 3-h postabsorptive period followed by a 3-h hyperinsulinemic-euglycemic clamp (HEC). Lipolysis rate, endogenous glucose production (EGP), and delta glucose rate of disappearance (ΔRdglu) were evaluated using [9,10-3H]palmitate and [3-3H]glucose tracers. In addition, whole body- and forearm protein metabolism was assessed using [15N]phenylalanine, [2H4]tyrosine, [15N]tyrosine, and [13C]urea tracers. In the postabsorptive period, plasma lactate increased to 2.7 ± 0.5 mmol/L during LAC vs. 0.6 ± 0.3 mmol/L during CTR (P < 0.001). In the postabsorptive period, palmitate flux was 30% lower during LAC compared with CTR (84 ± 32 µmol/min vs. 120 ± 35 µmol/min, P = 0.003). During the HEC, palmitate flux was suppressed similarly during both interventions (P = 0.7). EGP, ΔRdglu, and M value were similar during LAC and CTR. During HEC, LAC increased whole body phenylalanine flux (P = 0.02) and protein synthesis (P = 0.03) compared with CTR; LAC did not affect forearm protein metabolism compared with CTR. Lactate infusion inhibited lipolysis by 30% under postabsorptive conditions but did not affect glucose metabolism or improve insulin sensitivity. In addition, whole body phenylalanine flux was increased. Clinical trial registrations: NCT04710875.NEW & NOTEWORTHY Lactate is a decisive intermediary metabolite, serving as an energy substrate and a signaling molecule. The present study examines the effects of lactate on substrate metabolism and insulin sensitivity in healthy males. Hyperlactatemia reduces lipolysis by 30% without affecting insulin sensitivity and glucose metabolism. In addition, hyperlactatemia increases whole body amino acid turnover rate.

Lactate infusion elevates cardiac output through increased heart rate and decreased vascular resistance: a randomised, blinded, crossover trial in a healthy porcine model.

BACKGROUND: Lactate is traditionally recognized as a by-product of anaerobic metabolism. However, lactate is a preferred oxidative substrate for stressed myocardium. Exogenous lactate infusion increases cardiac output (CO). The exact mechanism underlying this mechanism has yet to be elucidated. The aim of this study was to investigate the cardiovascular mechanisms underlying the acute haemodynamic effects of exogenous lactate infusion in an experimental model of human-sized pigs. METHODS: In this randomised, blinded crossover study in eight 60-kg-pigs, the pigs received infusions with one molar sodium lactate and a control infusion of tonicity matched hypertonic saline in random order. We measured CO and pulmonary pressures using a pulmonary artery catheter. A pressure-volume admittance catheter in the left ventricle was used to measure contractility, afterload, preload and work-related parameters. RESULTS: Lactate infusion increased circulating lactate levels by 9.9 mmol/L (95% confidence interval (CI) 9.1 to 11.0) and CO by 2.0 L/min (95% CI 1.2 to 2.7). Afterload decreased as arterial elastance fell by  -1.0 mmHg/ml (95% CI  -2.0 to  -0.1) and systemic vascular resistance decreased by  -548 dynes/s/cm5 (95% CI  -261 to  -835). Mixed venous saturation increased by 11 percentage points (95% CI 6 to 16), whereas ejection fraction increased by 16.0 percentage points (95% CI 1.1 to 32.0) and heart rate by 21 bpm (95% CI 8 to 33). No significant changes in contractility nor preload were observed. CONCLUSION: Lactate infusion increased cardiac output by increasing heart rate and lowering afterload. No differences were observed in left ventricular contractility or preload. Lactate holds potential as a treatment in situations with lowered CO and should be investigated in future clinical studies.

Risk of Psychiatric Disorders, Use of Psychiatric Hospitals, and Receipt of Psychiatric Medication in Patients With Brain Abscess in Denmark.

BACKGROUND: It is unknown whether patients diagnosed with brain abscess have an increased risk of psychiatric disorders. METHODS: In this nationwide, population-based matched cohort study from Denmark, we compared the incidence of psychiatric disorders, use of psychiatric hospitals, and receipt of psychiatric medications between patients diagnosed with brain abscess and individuals from the general population, matched on date of birth, sex, and residential area. RESULTS: We included 435 patients diagnosed with brain abscess and 3909 individuals in the comparison cohort: 61% were male and median age was 54 years. Patients diagnosed with brain abscess were more likely to suffer from comorbidity. The risk of a hospital diagnosis of psychiatric disorders was increased the first 5 years of observation. In the subpopulation, who had never been in contact with psychiatric hospitals or received psychiatric medication before study inclusion, the risk of developing psychiatric disorders was close to that of the background population, especially when we excluded dementia from this outcome. There was a substantial increase in the receipt of anxiolytics and antidepressants. The difference in the proportion of individuals who received anxiolytics and antidepressants increased from 4% (95% confidence interval [CI], 0%-7%) and 2% (95% CI, -1% to 5%) 2 years before study inclusion to 17% (95% CI, 12%-21%) and 11% (95% CI, 7%-16%) in the year after study inclusion. CONCLUSIONS: Patients with brain abscess without prior psychiatric disorders or receipt of psychiatric medicine are not at increased risk psychiatric disorders diagnosed in psychiatric hospitals, but they have an increased receipt of psychiatric medication.

Oral 3-hydroxybuturate ingestion acutely lowers circulating testosterone concentrations in healthy young males.

Ketone bodies, such as 3-hydroxybutyrate (3-OHB), have been frequently used by endurance athletes, such as cyclists, to enhance performance and recovery and are recognized for their health benefits and therapeutic effects for decades. Testosterone is a potent regulator of red blood cell production. Evidence suggests that ketone bodies can increase the production of erythropoietin, which stimulates red blood cell production. Therefore, we investigated whether an acute increase in 3-OHB levels affects testosterone levels in healthy young men. We studied six healthy, young male participants who fasted overnight and were tested twice: (i) after drinking 37.5 g of Na-D/L-3-OHB dissolved in 500 mL of distilled water (KET), and (ii) after drinking 500 mL of placebo saline water (0.9% NaCl) (CTR). During the KET trial, 3-OHB levels increased to approximately 2.5 mM. Testosterone levels decreased significantly by 20% during KET compared to 3% during CTR. A simultaneous increase in luteinizing hormone was observed in KET. We observed no changes in other adrenal androgens, such as androstenedione and 11-keto androgens. In conclusion, an acute increase in 3-OHB levels decreases testosterone levels. Concomitantly, an increase in luteinizing hormone was observed. This suggests that 3-OHB may counteract some of the beneficial effects of endurance training. Further studies, involving larger sample sizes and performance outcomes, are required to fully understand this phenomenon.

Dentist's Visits and Risk of Brain Abscess: A Nationwide, Population-Based Case-Control Study.

BACKGROUND: Brain abscesses are frequently caused by oral cavity bacteria, but whether dental status and invasive dental procedures are important risk factors is unknown. METHODS: A nationwide, population-based, case-control study examined the association between dentist's visits and invasive dental procedures and risk of brain abscess caused by oral cavity bacteria from 1989 through 2016. Date of brain abscess diagnosis was considered the index date. Using risk-set sampling, 10 population controls per case were individually matched by age, sex, and residential area. Conditional logistic regression was used to compute odds ratios with 95% confidence intervals (CIs), adjusted for comorbidity. RESULTS: We identified 362 patients with culture-proven brain abscess caused by oral cavity bacteria. The median age was 53 years (interquartile range, 39-65 years) and 220 (61%) were male. Invasive dental procedures within 6 months before the index date was observed in 21 of 362 (6%) patients with brain abscess and 179 of 3257 (5%) population controls (adjusted odds ratio [aOR], 1.07 [95% CI, .67-1.70]). Two hundred thirteen of 362 (59%) patients with brain abscess had visited their dentist within 1 year before the index date compared with 1944 of 3257 (60%) of population controls (aOR, 0.99 [95% CI, .77-1.26]). Using no dentist's visits as reference, we observed aORs of 0.95 (95% CI, .64-1.40) for 1-2 visits within 3 years of the index date and 1.01 (95% CI, .76-1.35) for 3 or more visits. CONCLUSIONS: Recent invasive dental procedures and number of dentist's visits were not associated with culture-verified brain abscess caused by oral cavity bacteria.

Pivmecillinam, the paradigm of an antibiotic with low resistance rates in Escherichia coli urine isolates despite high consumption.

OBJECTIVES: Pivmecillinam, the oral version of mecillinam, represents one of the major recommended and used antibiotics for empiric and targeted treatment of urinary tract infections in primary care in Denmark, Norway and Sweden. Mecillinam resistant mutants in Escherichia coli develop easily in vitro, but their fitness cost has been shown to be high. METHODS: We revisited the resistance and consumption data from the monitoring programmes in the three countries and compared pivmecillinam with ciprofloxacin from 2010 to 2020. RESULTS: Mecillinam resistance rates in Escherichia coli remained around 6% in Denmark and Norway relative to a constant consumption in Norway of 1.6-1.8 DID (defined daily doses per 1000 inhabitants per day), and even increasing in Denmark from 1.6 to 2.3 DID. In Sweden resistance was significantly lower at 4% related to the lower consumption of 0.5 DID. For ciprofloxacin, resistance rates fluctuated around 6%-12%, highest in Sweden with the highest consumption (0.8-0.6 DID) and lowest in Denmark (0.55-0.35 DID) and Norway (0.7-0.3 DID), although consumption declined significantly in all three countries. CONCLUSIONS: Pivmecillinam is an example of an antibiotic, which easily develops resistance in vitro, but apparently can be used broadly in primary care without increase in resistance rates.

Three months of melatonin treatment reduces insulin sensitivity in patients with type 2 diabetes-A randomized placebo-controlled crossover trial.

The use of the sleep-promoting hormone melatonin is rapidly increasing as an assumed safe sleep aid. During the last decade, accumulating observations suggest that melatonin affects glucose homeostasis, but the precise role remains to be defined. We investigated the metabolic effects of long-term melatonin treatment in patients with type 2 diabetes including determinations of insulin sensitivity and glucose-stimulated insulin secretion. We used a double-blinded, randomized, placebo-controlled, crossover design. Seventeen male participants with type 2 diabetes completed (1) 3 months of daily melatonin treatment (10 mg) 1 h before bedtime (M) and (2) 3 months of placebo treatment 1 h before bedtime (P). At the end of each treatment period, insulin secretion was assessed by an intravenous glucose tolerance test (0.3 g/kg) (IVGTT) and insulin sensitivity was assessed by a hyperinsulinemic-euglycemic clamp (insulin infusion rate 1.5 mU/kg/min) (primary endpoints). Insulin sensitivity decreased after melatonin (3.6 [2.9-4.4] vs. 4.1 [3.2-5.2] mg/(kg × min), p = .016). During the IVGTT, the second-phase insulin response was increased after melatonin (p = .03). In conclusion, melatonin treatment of male patients with type 2 diabetes for 3 months decreased insulin sensitivity by 12%. Clinical use of melatonin treatment in dosages of 10 mg should be reserved for conditions where the benefits will outweigh the potential negative impact on insulin sensitivity.

Comparable Outcomes of Short-Course and Prolonged-Course Therapy in Selected Cases of Methicillin-Susceptible Staphylococcus aureus Bacteremia: A Pooled Cohort Study.

BACKGROUND: The recommended duration of antimicrobial treatment for Staphylococcus aureus bacteremia (SAB) is a minimum of 14 days. We compared the clinical outcomes of patients receiving short-course (SC; 6-10 days), or prolonged-course (PC; 11-16 days) antibiotic therapy for low-risk methicillin-susceptible SAB (MS-SAB). METHODS: Adults with MS-SAB in 1995-2018 were included from 3 independent retrospective cohorts. Logistic regression models fitted with inverse probability of treatment weighting were used to assess the association between the primary outcome of 90-day mortality and treatment duration for the individual cohorts as well as a pooled cohort analysis. RESULTS: A total of 645, 219, and 141 patients with low-risk MS-SAB were included from cohorts I, II, and III. Median treatment duration in the 3 SC groups was 8 days (interquartile range [IQR], 7-10), 9 days (IQR, 8-10), and 8 days (IQR, 7-10). In the PC groups, patients received a median therapy of 14 days (IQR, 13-15), 14 days (IQR, 13-15), and 13 days (IQR, 12-15). No significant differences in 90-day mortality were observed between the SC and PC group in cohort I (odds ratio [OR], 0.85 [95% confidence interval {CI}, .49-1.41]), cohort II (OR, 1.24 [95% CI, .60-2.62]), or cohort III (OR, 1.15 [95% CI, .24-4.01]). This result was consistent in the pooled cohort analysis (OR, 1.05 [95% CI, .71-1.51]). Furthermore, duration of therapy was not associated with the risk of relapse. CONCLUSIONS: In patients with low-risk MS-SAB, shorter courses of antimicrobial therapy yielded similar clinical outcomes as longer courses of therapy.

Effective antimicrobial combination in vivo treatment predicted with microcalorimetry screening.

OBJECTIVES: The worldwide emergence of antibiotic resistance calls for effective exploitation of existing antibiotics. Antibiotic combinations with different modes of action can synergize for successful treatment. In the present study, we used microcalorimetry screening to identify synergistic combination treatments against clinical MDR isolates. The synergistic effects were validated in a murine infection model. METHODS: The synergy of meropenem combined with colistin, rifampicin or amikacin was tested on 12 isolates (1 Escherichia coli, 5 Klebsiella pneumoniae, 3 Pseudomonas aeruginosa and 3 Acinetobacter baumannii) in an isothermal microcalorimeter measuring metabolic activity. One A. baumannii strain was tested with two individual pairings of antibiotic combinations. The microcalorimetric data were used to predict in vivo efficacy in a murine peritonitis/sepsis model. NMRI mice were inoculated intraperitoneally and after 1 h treated with saline, drug X, drug Y or X+Y. Bacterial load was determined by cfu in peritoneal fluid and blood after 4 h. RESULTS: In vitro, of the 13 combinations tested on the 12 strains, 3 of them exhibited a synergistic reduction in MIC (23% n = 3/13), 5 showed an additive effect (38.5% n = 5/13) and 5 had indifferent or antagonistic effects (38.5% n = 5/13). There was a significant correlation (P = 0.024) between microcalorimetry-screening FIC index values and the log reduction in peritoneal fluid from mice that underwent combination treatment compared with the most effective mono treatment. No such correlation could be found between chequerboard and in vivo results (P = 0.16). CONCLUSIONS: These data support microcalorimetic metabolic readout to predict additive or synergistic effects of combination treatment of MDR infections within hours.

ß-Lactoglobulin Is Insulinotropic Compared with Casein and Whey Protein Ingestion during Catabolic Conditions in Men in a Double-Blinded Randomized Crossover Trial.

BACKGROUND: Muscle loss during acute infectious disease is mainly triggered by inflammation, immobilization, and malnutrition. OBJECTIVE: The objective was to compare muscle protein kinetics and metabolism following ingestion of the dairy protein supplements ß-lactoglobulin (BLG), casein (CAS), and whey (WHE) during controlled catabolic conditions. METHODS: We used a randomized crossover design (registered at clinicaltrials.gov as NCT03319550) to investigate 9 healthy male participants [age: 20-40 y; BMI (in kg/m2) 20-30] who were randomly assigned servings of BLG, CAS, or WHE (0.6 g protein/kg, one-third as bolus and two-thirds as sip every 20 min) on 3 separate occasions separated by ∼6-8 wk. The participants received an infusion of lipopolysaccharide (1 ng/kg) combined with 36 h of fasting and bed rest before each study day, mimicking a clinical catabolic condition. The forearm model and isotopic tracer techniques were used to quantify muscle protein kinetics. Muscle biopsy specimens were obtained and intramyocellular signaling investigated using Western blot. RESULTS: BLG, CAS, and WHE improved the net balance of phenylalanine (NBphe) from baseline with ∼75% (P < 0.001) with no difference between interventions (primary outcome, P < 0.05). No difference in rates of appearance and disappearance of phenylalanine or in intramyocellular signaling activation was found between interventions (secondary outcomes). The incremental AUC for serum insulin was 62% higher following BLG compared with CAS (P < 0.001) and 30% higher compared with WHE (P = 0.002), as well as 25% higher in WHE compared with CAS (P = 0.006). Following BLG consumption, plasma concentrations of glucose-dependent insulinotropic peptide (GIP) increased 70% compared with CAS (P = 0.001) and increased 34% compared with WHE (P = 0.06). No significant difference was found between WHE and CAS (P = 0.12). CONCLUSION: BLG, WHE, and CAS have similar effects on muscle in young male participants during catabolic conditions. BLG showed specific, possibly GIP-dependent, insulinotropic properties, which may have future clinical implications.

Hyperpolarized [1-13 C]pyruvate combined with the hyperinsulinaemic euglycaemic and hypoglycaemic clamp technique in skeletal muscle in a large animal model.

NEW FINDINGS: What is the central question of this study? Is it possible to combine the hyperpolarized magnetic resonance technique and the hyperinsulinaemic clamp method in order to evaluate skeletal muscle metabolism in a large animal model? What is the main finding and its importance? The logistical set-up is possible, and we found substantial increments in glucose infusion rates representing skeletal muscle glucose uptake but no differences in ratios of [1-13 C]lactate to [1-13 C]pyruvate, [1-13 C]alanine to [1-13 C]pyruvate, and 13 C-bicarbonate to [1-13 C]pyruvate, implying that the hyperpolarization technique might not be optimal for detecting effects of insulin in skeletal muscle of anaesthetized animals, which is of significance for future studies. ABSTRACT: In skeletal muscle, glucose metabolism is tightly regulated by the reciprocal relationship between insulin and adrenaline, with pyruvate being at the intersection of both pathways. Hyperpolarized magnetic resonance (hMR) is a new approach to gain insights into these pathways, and human trials involving hMR and skeletal muscle metabolism are imminent. We aimed to combine the hyperinsulinaemic clamp technique and hMR in a large animal model resembling human physiology. Fifteen anaesthetized pigs were randomized to saline (control group), hyperinsulinaemic euglycaemic clamp technique (HE group) or hyperinsulinaemic hypoglycaemic clamp technique (HH group). Skeletal muscle metabolism was evaluated by hyperpolarized [1-13 C]pyruvate injection and hMR at baseline and after intervention. The glucose infusion rate per kilogram increased by a statistically significant amount in the HE and HH groups (P < 0.001). Hyperpolarized magnetic resonance showed no statistically significant changes in metabolite ratios: [1-13 C]lactate to [1-13 C]pyruvate in the HH group versus control group (P = 0.19); and 13 C-bicarbonate to [1-13 C]pyruvate ratio in the HE group versus the control group (P = 0.12). We found evidence of profound increments in glucose infusion rates representing skeletal muscle glucose uptake, but interestingly, no signs of significant changes in aerobic and anaerobic metabolism using hMR. These results imply that hyperpolarized [1-13 C]pyruvate might not be optimally suited to detect effects of insulin in anaesthetized resting skeletal muscle, which is of significance for future studies.

Acute ketosis inhibits appetite and decreases plasma concentrations of acyl ghrelin in healthy young men.

AIM: To investigate the acute effect of ketone ester (KE) ingestion on appetite and plasma concentrations of acyl ghrelin (AG), unacylated ghrelin (UAG) and glucagon-like peptide-1 (GLP-1) secretion, and to compare responses with those elicited by isocaloric glucose (GLU) administration. METHODS: We examined 10 healthy young men on three separate occasions using a placebo (PBO)-controlled crossover design. A KE versus taste-matched isovolumetric and isocaloric 50% GLU and taste-matched isovolumetric PBO vehicle was orally administered. Our main outcome measures were plasma concentrations of AG, UAG, glucose-dependent insulinotropic polypeptide (GIP) and GLP-1 along with appetite sensation scores assessed by visual analogue scale. RESULTS: KE ingestion resulted in an average peak beta-hydroxybutyrate concentration of 5.5 mM. AG and UAG were lowered by approximately 25% following both KE and GLU intake compared with PBO. In the case of AG, the differences were -52.1 (-79.4, -24.8) for KE and -48.4 (-75.4, -21.5) pg/mL for GLU intake (P < .01). Concentrations of AG remained lower with KE but returned to baseline and were comparable with PBO levels after GLU intake. GLP-1, GIP, gastrin and cholecystokinin were not affected by KE ingestion. CONCLUSION: Our results suggest that the suppressive effects on appetite sensation scores associated with hyperketonaemia are more probable to be mediated through reduced ghrelin concentrations than by increased activity of cholecystokinin, gastrin, GIP or GLP-1.

Hospital readmissions following infections in dementia: a nationwide and registry-based cohort study.

INTRODUCTION: We aimed to investigate readmission risks following infections in dementia, identify the types of infections behind the risks, and highlight the reasons for readmissions. METHODS: Acute inpatient hospital admissions for infections in Danish residents were included from 1 January 2000, or age 65 years. Primary outcomes were 7-day readmissions risk ratios (RRs; risk following infection index admissions of people with dementia relative to those without dementia), risks by infection site, and reasons for readmission. Secondary outcomes were 30- and 90-day readmission risks. Competing risk of death was estimated. RESULTS: Seven-day readmission RR was increased in all age groups and was highest in the youngest patients (women RR: 1.37, 95% confidence interval [CI] 1.22-1.53; men RR: 1.23, 95% CI 1.12-1.35). RRs decreased with increasing age and longer follow-up. The most notable common readmissions were for infections and dehydration in dementia. CONCLUSIONS: We conclude that there is a substantially increased readmission risk in people with dementia than in those without dementia, particularly within 7 days, and for the youngest in the cohort. Readmission risks were higher for infection index admissions than for admissions for causes other than infection, and readmissions were mostly due to infections. Our findings highlight the burden of infections in people with dementia and call for in-depth investigations of determinants related to readmission risks, to inform public policy and identify avenues for interventions that can decrease or prevent potentially avoidable readmissions.

Acute metabolic effects of melatonin-A randomized crossover study in healthy young men.

Melatonin regulates circadian rhythm, but may also have effects on glucose homeostasis. A common G-allele in the MTNR1B locus has been associated with an increased risk of type 2 diabetes (T2DM). We aimed to examine acute effects of high doses of melatonin on glucose metabolism with attention to MTNR1B genotype. Twenty men were examined in a double-blinded, randomized crossover study on two nonconsecutive days with four doses of 10 mg oral melatonin or placebo. Insulin sensitivity and insulin secretion were assessed by an intravenous glucose tolerance test (IVGTT) and a hyperinsulinaemic-euglycaemic clamp (HEC). Blood samples were drawn to determine the metabolic profile and MTNR1B rs10830963 genotype. Indirect calorimetry and blood pressure measurements were also performed. Insulin sensitivity index was significantly reduced on the melatonin day (P = .028) in the whole group and in homozygous carriers of the rs10830963 C-allele (P = .041). Glucose during the IVGTT was unaffected, but there was a tendency towards lower insulin and C-peptide levels in the first minutes after glucose administration in G-allele carriers. Systolic blood pressure decreased and lipid oxidation increased significantly on the melatonin day in rs10830963 G-allele carriers. Overall, our study reports that acute administration of melatonin in supra-physiological doses may have a negative impact on insulin sensitivity. Clinical trial registration number (clinicaltrial.gov): NCT03204877.

Metformin Lowers Body Weight But Fails to Increase Insulin Sensitivity in Chronic Heart Failure Patients without Diabetes: a Randomized, Double-Blind, Placebo-Controlled Study.

PURPOSE: The glucose-lowering drug metformin has recently been shown to reduce myocardial oxygen consumption and increase myocardial efficiency in chronic heart failure (HF) patients without diabetes. However, it remains to be established whether these beneficial myocardial effects are associated with metformin-induced alterations in whole-body insulin sensitivity and substrate metabolism. METHODS: Eighteen HF patients with reduced ejection fraction and without diabetes (median age, 65 (interquartile range 55-68); ejection fraction 39 ± 6%; HbA1c 5.5 to 6.4%) were randomized to receive metformin (n = 10) or placebo (n = 8) for 3 months. We studied the effects of metformin on whole-body insulin sensitivity using a two-step hyperinsulinemic euglycemic clamp incorporating isotope-labeled tracers of glucose, palmitate, and urea. Substrate metabolism and skeletal muscle mitochondrial respiratory capacity were determined by indirect calorimetry and high-resolution respirometry, and body composition was assessed by bioelectrical impedance analysis. The primary outcome measure was change in insulin sensitivity. RESULTS: Compared with placebo, metformin treatment lowered mean glycated hemoglobin levels (absolute mean difference, - 0.2%; 95% CI - 0.3 to 0.0; p = 0.03), reduced body weight (- 2.8 kg; 95% CI - 5.0 to - 0.6; p = 0.02), and increased fasting glucagon levels (3.2 pmol L-1; 95% CI 0.4 to 6.0; p = 0.03). No changes were observed in whole-body insulin sensitivity, endogenous glucose production, and peripheral glucose disposal or oxidation with metformin. Equally, resting energy expenditure, lipid and urea turnover, and skeletal muscle mitochondrial respiratory capacity remained unaltered. CONCLUSION: Increased myocardial efficiency during metformin treatment is not mediated through improvements in insulin action in HF patients without diabetes. CLINICAL TRIAL REGISTRATION: URL: https://clinicaltrials.gov . Unique identifier: NCT02810132. Date of registration: June 22, 2016.

School-based interventions modestly increase physical activity and cardiorespiratory fitness but are least effective for youth who need them most: an individual participant pooled analysis of 20 controlled trials.

OBJECTIVES: To determine if subpopulations of students benefit equally from school-based physical activity interventions in terms of cardiorespiratory fitness and physical activity. To examine if physical activity intensity mediates improvements in cardiorespiratory fitness. DESIGN: Pooled analysis of individual participant data from controlled trials that assessed the impact of school-based physical activity interventions on cardiorespiratory fitness and device-measured physical activity. PARTICIPANTS: Data for 6621 children and adolescents aged 4-18 years from 20 trials were included. MAIN OUTCOME MEASURES: Peak oxygen consumption (VO2Peak mL/kg/min) and minutes of moderate and vigorous physical activity. RESULTS: Interventions modestly improved students' cardiorespiratory fitness by 0.47 mL/kg/min (95% CI 0.33 to 0.61), but the effects were not distributed equally across subpopulations. Girls and older students benefited less than boys and younger students, respectively. Students with lower levels of initial fitness, and those with higher levels of baseline physical activity benefitted more than those who were initially fitter and less active, respectively. Interventions had a modest positive effect on physical activity with approximately one additional minute per day of both moderate and vigorous physical activity. Changes in vigorous, but not moderate intensity, physical activity explained a small amount (~5%) of the intervention effect on cardiorespiratory fitness. CONCLUSIONS: Future interventions should include targeted strategies to address the needs of girls and older students. Interventions may also be improved by promoting more vigorous intensity physical activity. Interventions could mitigate declining youth cardiorespiratory fitness, increase physical activity and promote cardiovascular health if they can be delivered equitably and their effects sustained at the population level.

Impact of Acutely Increased Endogenous- and Exogenous Ketone Bodies on FGF21 Levels in Humans.

PURPOSE: Fibroblast growth factor (FGF) 21 is a circulating hormone with metabolic regulatory importance. In mice, FGF21 increases in response to a ketogenic diet and fasting. In humans, a similar increase is only observed after prolonged starvation. We aim to study the acute effects of ketone bodies on circulating FGF21 levels in humans. METHODS: Participants from three randomized, placebo-controlled crossover studies, with increased endogenous or exogenous ketone bodies, were included. Study 1: patients with type 1 diabetes (T1D) (n = 9) were investigated after a) insulin deprivation and lipopolysaccharide (LPS) injection and b) insulin-controlled euglycemia. Study 2: patients with T1D (n = 9) were investigated after a) total insulin deprivation for 9 hours and b) insulin-controlled euglycemia. Study 3: Healthy adults (n = 9) were examined during a) 3-hydroxybutyrate (OHB) infusion and b) saline infusion. Plasma FGF21 was measured with immunoassay in serial samples. RESULTS: Circulating OHB levels were significantly increased to 1.3, 1.5, and 5.5 mmol/l in the three studies, but no correlations with FGF21 levels were found. Also, no correlations between FGF21, insulin, or glucagon were found. Insulin deprivation and LPS injection resulted in increased plasma FGF21 levels at t = 120 min (p = .005) which normalized at t = 240 min. CONCLUSION: We found no correlation between circulating FGF21 levels and levels of ketone bodies. This suggests that it is not ketosis per se which controls FGF21 production, but instead a rather more complex regulatory mechanism. TRIAL REGISTRATION: clinicaltrials.gov ID number: Study 1: NCT02157155 (5/6-2014), study 2: NCT02077348 (4/3-2014), and study 3: NCT02357550 (6/2-2015).

Manual Annotation of Time in Bed Using Free-Living Recordings of Accelerometry Data.

With the emergence of machine learning for the classification of sleep and other human behaviors from accelerometer data, the need for correctly annotated data is higher than ever. We present and evaluate a novel method for the manual annotation of in-bed periods in accelerometer data using the open-source software Audacity®, and we compare the method to the EEG-based sleep monitoring device Zmachine® Insight+ and self-reported sleep diaries. For evaluating the manual annotation method, we calculated the inter- and intra-rater agreement and agreement with Zmachine and sleep diaries using interclass correlation coefficients and Bland-Altman analysis. Our results showed excellent inter- and intra-rater agreement and excellent agreement with Zmachine and sleep diaries. The Bland-Altman limits of agreement were generally around ±30 min for the comparison between the manual annotation and the Zmachine timestamps for the in-bed period. Moreover, the mean bias was minuscule. We conclude that the manual annotation method presented is a viable option for annotating in-bed periods in accelerometer data, which will further qualify datasets without labeling or sleep records.

Insulin resistance induced by growth hormone is linked to lipolysis and associated with suppressed pyruvate dehydrogenase activity in skeletal muscle: a 2 × 2 factorial, randomised, crossover study in human individuals.

AIMS/HYPOTHESIS: Growth hormone (GH) causes insulin resistance that is linked to lipolysis, but the underlying mechanisms are unclear. We investigated if GH-induced insulin resistance in skeletal muscle involves accumulation of diacylglycerol (DAG) and ceramide as well as impaired insulin signalling, or substrate competition between fatty acids and glucose. METHODS: Nine GH-deficient male participants were randomised and examined in a 2 × 2 factorial design with and without administration of GH and acipimox (an anti-lipolytic compound). As-treated analyses were performed, wherefore data from three visits from two patients were excluded due to incorrect GH administration. The primary outcome was insulin sensitivity, expressed as the AUC of the glucose infusion rate (GIRAUC), and furthermore, the levels of DAGs and ceramides, insulin signalling and the activity of the active form of pyruvate dehydrogenase (PDHa) were assessed in skeletal muscle biopsies obtained in the basal state and during a hyperinsulinaemic-euglycaemic clamp (HEC). RESULTS: Co-administration of acipimox completely suppressed the GH-induced elevation in serum levels of NEFA (GH versus GH+acipimox, p < 0.0001) and abrogated GH-induced insulin resistance (mean GIRAUC [95% CI] [mg min-1 kg-1] during the HEC: control, 595 [493, 718]; GH, 468 [382, 573]; GH+acipimox, 654 [539, 794]; acipimox, 754 [618, 921]; GH vs GH+acipimox: p = 0.004). GH did not significantly change either the accumulation of DAGs and ceramides or insulin signalling in skeletal muscle, but GH antagonised the insulin-stimulated increase in PDHa activity (mean ± SEM [% from the basal state to the HEC]: control, 47 ± 19; GH, -15 ± 21; GH+acipimox, 3 ± 21; acipimox, 57 ± 22; main effect: p = 0.02). CONCLUSIONS/INTERPRETATION: GH-induced insulin resistance in skeletal muscle is: (1) causally linked to lipolysis; (2) not associated with either accumulation of DAGs and ceramides or impaired insulin signalling; (3) likely to involve substrate competition between glucose and lipid intermediates. TRIAL REGISTRATION: ClinicalTrials.gov NCT02782208 FUNDING: The work was supported by the Grant for Growth Innovation (GGI), which was funded by Merck KGaA, Darmstadt, Germany. Graphical abstract.