Anti-obesity and metabolic benefits of metformin: Comparison of different delivery routes

Obesity is a severe public health problem. Healthy lifestyle interventions are commonly recommended for fighting obesity. But they are hard to follow and have low efficacy. Pharmacotherapy and surgery are of high efficacy but are beset with side effects. Browning subcutaneous white adipose tissue (WAT) is a practical and efficient approach for combating obesity. Metformin, a commonly used FDA-approved antidiabetic drug, is potent to induce browning of WAT through phosphorylation and activation of AMP-activated protein kinase. However, oral administration of metformin has low oral bioavailability, fast renal clearance, and low target specificity that limit metformin's application in browning WAT. Local and transdermal delivery of metformin directly to subcutaneous WAT using injection or microneedle (MN) in combination with iontophoresis (INT) may solve these problems. In this paper, we administered metformin to C57BL/6J obese mice using the following three routes: transdermal delivery (MN and INT), local injection into inguinal WAT (IgWAT, a type of subcutaneous WAT in mice), and oral gavage. The anti-obesity and metabolic effects of metformin via these delivery routes were determined and compared. As compared to local IgWAT injection and oral gavage delivery, transdermal delivery of metformin using MN and INT resulted in 9% lower body weight and 7% decrease in body fat% accompanied by improved energy metabolism and decreased inflammation through browning IgWAT in obese C57BL/6J mice. Transdermal delivery of metformin using MN and INT is an effective approach in browning subcutaneous WAT for combating obesity and improving metabolic health.

Maintaining normothermia immediately after birth in preterm infants <34 weeks' gestation: A systematic review and meta-analysis

AIM

To evaluate delivery room (DR) interventions to prevent hypothermia and improve outcomes in preterm newborn infants <34 weeks' gestation.

METHODS

Medline, Embase, CINAHL and CENTRAL were searched till 22nd July 2022. Randomized controlled trials (RCTs), non-RCTs and quality improvement studies were considered. A random effects meta-analysis was performed, and the certainty of evidence was evaluated using GRADE guidelines.

RESULTS

DR temperature of ≥23 °C compared to standard care improved temperature outcomes without an increased risk of hyperthermia (low certainty), whereas radiant warmer in servo mode compared to manual mode decreased mean body temperature (MBT) (moderate certainty). Use of a plastic bag or wrap (PBW) improved normothermia (low certainty), but with an increased risk of hyperthermia (moderate certainty). Plastic cap improved normothermia (moderate certainty) and when combined with PBW improved MBT (low certainty). Use of a cloth cap decreased moderate hypothermia (low certainty). Though thermal mattress (TM) improved MBT, it increased risk of hyperthermia (low certainty). Heated-humidified gases (HHG) for resuscitation decreased the risk of moderate hypothermia and severe intraventricular hemorrhage (very low to low certainty). None of the interventions was shown to improve survival, but sample sizes were insufficient.

CONCLUSIONS

DR temperature of ≥23 °C, radiant warmer in manual mode, use of a PBW and a head covering is suggested for preterm newborn infants <34 weeks' gestation. HHG and TM could be considered in addition to PBW provided resources allow, in settings where hypothermia incidence is high. Careful monitoring to avoid hyperthermia is needed.

Effects of a Theory-Based, Multicomponent eHealth Intervention for Obesity Prevention in Young Children from Low-Income Families: A Pilot Randomized Controlled Study

The purpose of this study was to evaluate a theory-based, multicomponent eHealth intervention aimed at improving child health behaviors and parental psychosocial attributes and feeding practices. A pilot randomized controlled trial was conducted among 73 parents with children (1-3 years). Intervention group participants (IG, n = 37) received theory-based educational videos, cooking tutorials, and text messages with key information for a total of 8 weeks. Control group participants (CG, n = 36) received a booklet about general nutrition recommendations for children. A parent-administered questionnaire was used for data collection at baseline and post-intervention. Linear models were performed using R version 4.1.1. for data analysis. Children in the IG significantly increased their daily intake of fruit (ΔΔ = 0.89 servings, p = 0.00057) and vegetables (ΔΔ = 0.60 servings, p = 0.0037) and decreased use of screen time (ΔΔ = -33.87 min, p = 0.026), compared to the CG. Parents in the IG improved significantly more than the CG in self-efficacy (p = 0.0068) and comprehensive feeding practices (p = 0.0069). There were no significant differences between the study groups for changes in child outcomes, such as physical activity and sedentary behaviors, and parental nutrition knowledge and attitudes.

A Culturally Sensitive and Theory-Based Intervention on Prevention and Management of Diabetes: A Cluster Randomized Control Trial

Type 2 diabetes is an emerging concern in Kenya. This clustered-randomized trial of peri-urban communities included a theory-based and culturally sensitive intervention to improve diabetes knowledge, health beliefs, dietary intake, physical activity, and weight status among Kenyan adults. Those in the intervention group (IG) received a culturally sensitive diabetes education intervention which applied the Health Belief Model in changing knowledge, health beliefs and behavior. Participants attended daily education sessions for 5 days, each lasting 3 h and received mobile phone messages for an additional 4 weeks. The control group (CG) received standard education on COVID-19. Data was collected at baseline, post-intervention (1 week), and follow-up assessment (5 weeks). Linear mixed effect analysis was performed to assess within and across group differences. Compared to the control, IG significantly increased diabetes knowledge (p < 0.001), health beliefs including perceived susceptibility (p = 0.05), perceived benefits (p = 0.04) and self-efficacy (p = 0.02). IG decreased consumption of oils (p = 0.03), refined grains (p = 0.01), and increased intake of fruits (p = 0.01). Perceived barriers, physical activity, and weight status were not significantly different between both groups. The findings demonstrate the potential of diabetes education in improving diabetes knowledge, health beliefs, and in changing dietary intake of among adults in Kenya.

Maintaining normal temperature immediately after birth in late preterm and term infants: A systematic review and meta-analysis

AIM

Prevention of hypothermia after birth is a global problem in late preterm and term neonates. The aim of this systematic review and meta-analysis was to evaluate delivery room strategies to maintain normothermia and improve survival in late preterm and term neonates (≥34 weeks' gestation).

METHODS

Medline, Embase, CINAHL, CENTRAL and international clinical trial registries were searched. Randomized controlled trials (RCTs), quasi-RCTs and observational studies were eligible for inclusion. Risk of bias for each study and GRADE certainty of evidence for each outcome were assessed.

RESULTS

25 RCTs and 10 non-RCTs were included. Room temperature of 23 °C compared to 20 °C improved normothermia [Risk Ratio (RR), 95% Confidence Interval (CI): 1.26, 1.11-1.42)] and body temperature [Mean Difference (MD), 95% CI: 0.30 °C, 0.23-0.37 °C), and decreased moderate hypothermia (RR, 95% CI: 0.26, 0.16-0.42). Skin to skin care (SSC) compared to no SSC increased body temperature (MD, 95% CI: 0.32, 0.10-0.52), reduced hypoglycemia (RR, 95% CI: 0.16, 0.05-0.53) and hospital admission (RR, 95% CI: 0.34, 0.14-0.83). Though plastic bag or wrap (PBW) alone or when combined with SSC compared to SSC alone improved temperatures, the risk-benefit balance is uncertain. Clinical benefit or harm could not be excluded for the primary outcome of survival for any of the interventions. Certainty of evidence was low to very low for all outcomes.

CONCLUSIONS

Room temperature of 23 °C and SSC soon after birth may prevent hypothermia in late preterm and term neonates. Though PBW may be an effective adjunct intervention, the risk-benefit balance needs further investigation.

Greater protein quality of an egg breakfast may be inadequate to induce satiety during weight loss, compared with a cereal breakfast of equal protein quantity

We compared the effects of consuming egg-breakfast of superior protein quality to cereal-breakfast of similar energy density and protein quantity, but lower protein quality. Two, two-week randomised crossover clinical trials included 30 otherwise healthy women with overweight or obesity. Subjects received counselling to follow a reduced-calorie diet. Under supervision, participants consumed either breakfast for one-week then crossed over to the opposite breakfast. Experiment-1 outcome variables included post-breakfast appetite hormones, glucose and insulin, subjective markers of satiety and energy intake at lunch and dinner. In Experiment-2, an appealing food (brownies) was included in lunch. Following the breakfasts, Experiment-1 showed no significant differences in outcome variables. In Experiment-2, the egg-breakfast increased fullness (p = 0.038), but lunch-time energy intake was not different. If these findings apply to other breakfasts, it suggests that in comparing two breakfasts with similar protein quantity, the greater protein quality of a breakfast may not be adequate to induce satiety.

Errors in the implementation, analysis, and reporting of randomization within obesity and nutrition research: a guide to their avoidance

Randomization is an important tool used to establish causal inferences in studies designed to further our understanding of questions related to obesity and nutrition. To take advantage of the inferences afforded by randomization, scientific standards must be upheld during the planning, execution, analysis, and reporting of such studies. We discuss ten errors in randomized experiments from real-world examples from the literature and outline best practices for their avoidance. These ten errors include: representing nonrandom allocation as random, failing to adequately conceal allocation, not accounting for changing allocation ratios, replacing subjects in nonrandom ways, failing to account for non-independence, drawing inferences by comparing statistical significance from within-group comparisons instead of between-groups, pooling data and breaking the randomized design, failing to account for missing data, failing to report sufficient information to understand study methods, and failing to frame the causal question as testing the randomized assignment per se. We hope that these examples will aid researchers, reviewers, journal editors, and other readers to endeavor to a high standard of scientific rigor in randomized experiments within obesity and nutrition research.

Browning white adipose tissue using adipose stromal cell-targeted resveratrol-loaded nanoparticles for combating obesity

Enhancing thermogenic energy expenditure via promoting the browning of white adipose tissue (WAT) is a potential therapeutic strategy to manage energy imbalance and the consequent comorbidities associated with excess body weight. Adverse effects and toxicities of currently available methods to induce browning of WAT have retarded exploration of this promising therapeutic approach. Targeted delivery of browning agents to adipose stromal cells (ASCs) in subcutaneous WAT to induce differentiation into beige adipocytes may overcome these barriers. Herein, we report for the first time, ASC-targeted delivery of trans-resveratrol (R), a representative agent, using ligand-coated R-encapsulated nanoparticles (L-Rnano) that selectively bind to glycanation site-deficient decorin receptors on ASCs. After biweekly intravenous administration of L-Rnano to obese C57BL/6 J mice for 5 weeks targeted R delivery significantly induced ASCs differentiation into beige adipocytes, which subsequently resulted in 40% decrease in fat mass, accompanied by improved glucose homeostasis and decreased inflammation. Our results suggest that the ASC-targeted nanoparticle delivery of browning agents could be a transformative technology in combating obesity and its comorbidities with high efficacy and low toxicity.

Persistent confusion in nutrition and obesity research about the validity of classic nonparametric tests in the presence of heteroscedasticity: evidence of the problem and valid alternatives

The use of classic nonparametric tests (cNPTs), such as the Kruskal-Wallis and Mann-Whitney U tests, in the presence of unequal variance for between-group comparisons of means and medians may lead to marked increases in the rate of falsely rejecting null hypotheses and decreases in statistical power. Yet, this practice remains prevalent in the scientific literature, including nutrition and obesity literature. Some nutrition and obesity studies use a cNPT in the presence of unequal variance (i.e., heteroscedasticity), sometimes because of the mistaken rationale that the test corrects for heteroscedasticity. Herein, we discuss misconceptions of using cNPTs in the presence of heteroscedasticity. We then discuss assumptions, purposes, and limitations of 3 common tests used to test for mean differences between multiple groups, including 2 parametric tests: Fisher's ANOVA and Welch's ANOVA; and 1 cNPT: the Kruskal-Wallis test. To document the impact of heteroscedasticity on the validity of these tests under conditions similar to those used in nutrition and obesity research, we conducted simple simulations and assessed type I error rates (i.e., false positives, defined as incorrectly rejecting the null hypothesis). We demonstrate that type I error rates for Fisher's ANOVA, which does not account for heteroscedasticity, and Kruskal-Wallis, which tests for differences in distributions rather than means, deviated from the expected significance level. Greater deviation from the expected type I error rate was observed as the heterogeneity increased, especially in the presence of an imbalanced sample size. We provide brief tutorial guidance for authors, editors, and reviewers to identify appropriate statistical tests when test assumptions are violated, with a particular focus on cNPTs.

No association between consumption of eggs with energy or macronutrient intake: Objective evidence from the remote food photography method

BACKGROUND AND AIMS

Greater egg consumption is associated with poor glycemic control. However, greater egg intake could simply be a marker for other dietary indiscretions such as greater intake of energy or saturated fat, which may influence glycemic control. We examined the association between egg consumption and total energy intake and saturated fat intake, measured using the remote food photography method.

METHODS

An observational study was conducted with 48 healthy adults consuming ≥1 eggs/week. Photographs of all meals consumed for seven days were captured via a smartphone application called SmartIntake® and analyzed for nutrient intake. Fasting blood samples were collected. Linear correlations between egg consumption and nutrient intake or measures of glycemic control were determined.

RESULTS

Daily egg intake was significantly associated with cholesterol intake, but not with the daily energy and saturated fat intake or measures of glycemic control.

CONCLUSIONS

Higher consumption of eggs in free-living conditions was not associated with undesirable profiles of macronutrient intake, total EI, or an impaired glycemic profile in this study population. Thus, the assertion that eggs are linked with impaired glycemic control because of the accompanying intake of greater energy and saturated fat, does not appear valid.

TRIAL REGISTRATION

NCT03404700.

Assessing Biota Accumulation Due to Contamination of Sediments by Storm Water Heavy Metals

Evaluating sediment recontamination due to storm water discharges is important when evaluating the long-term effectiveness of sediment remediation efforts at reducing biological impacts. The bioaccumulation of the heavy metals zinc, nickel, copper, cadmium, mercury, and lead and the metalloid arsenic in a clam (Macoma nasuta) was studied in surficial sediments before and after storm water inputs from Paleta Creek, California, USA, during wet seasons in 2015 to 2016 and 2016 to 2017. The bioaccumulation was compared with bulk sediment concentrations and porewater concentrations measured by diffusion gradient in thin film devices. Significant reductions in biota accumulation and porewater concentrations were observed in samples collected after storm seasons compared with before storm seasons despite bulk sediment concentrations remaining the same or increasing. This was apparently the result of the deposition of storm water contaminants in low bioavailable forms. The bioaccumulation of all the measured contaminants showed a positive significant correlation with porewater concentrations (p < 0.1, α = 0.1) and weak or no correlations with bulk sediment concentration. In conclusion, observed bulk sediment recontamination due to storm water should not be assumed to lead directly to greater biota accumulation without bioavailability assessment. Environ Toxicol Chem 2020;39:2475-2484. © 2020 SETAC.

Assessing sediment recontamination from metals in stormwater

Recontamination of sediments by stormwater is a major concern when evaluating the potential effectiveness of sediment remediation. Stormwater and sediment sampling were conducted in a mixed-use watershed at Paleta Creek in San Diego, CA to evaluate methods for assessing sediment recontamination by metals. Size-segregated stormwater contaminant loads with simultaneous receiving water and sediment measurements were used to identify dominant sources and contaminants with respect to their impact on sediment recontamination. Most of the stormwater contaminant loads of Cd, Cu, Pb, and Zn were associated with residential and highway sources from the upstream portions of the watershed and As, Ni and Hg were more significantly influenced by the downstream area of the watershed. Cd was strongly associated with large particles (>63 μm) and observed to settle in near shore areas with some attenuation due to mixing and dilution. Cu, in contrast, was associated more with the filtered fraction (<0.45 μm) and clay fraction (0.45-5 μm), resulting in less near shore sediment recontamination. Depositing sediment and other metals, particularly Cu and Hg, exhibited greater accumulation in settling traps than could be attributed to stormwater loads indicating the importance of other sources or resuspension of bay sediments on surficial sediment concentrations. Pb, Zn, Ni, and As showed influences of both stormwater and other sources. The study showed that measurement of size-segregated stormwater contaminant mass and concentrations combined with simultaneous measurements of deposition in sediment traps could differentiate between recontamination by stormwater and that of other sources.

Psychological and weight history variables as predictors of short-term weight and body fat mass loss

OBJECTIVE

Identifying predictors of early weight loss may have value in predicting longer-term success in weight loss programmes. This study examined if weight history variables (ie, weight cycling history [WCH], age of onset of obesity [AOO]), and preintervention Three-Factor Eating Questionnaire (TFEQ) and Power of Food Scale (PFS) scores predicted weight loss (WL) and fat mass loss (FML) following a 3-week calorie restriction intervention.

METHODS

Thirty-two participants (19-60 y; body mass index [BMI] 30-39.9 kg/m2) participated in a 3-week calorie restriction intervention (1120 kcal/d) as part of a larger clinical trial with 28 completers included in the current analyses. Preintervention WCH, AOO, TFEQ, and PFS subscale scores were collected, and WL and FML were measured. Multiple linear regression analyses were performed to predict WL and FML for relevant covariates in this study.

RESULTS

WCH, AOO, preintervention TFEQ subscale scores, and PFS subscale scores did not predict WL (all Ps > .08) or FML (Ps > .06) except, PFS-food tasted scores significantly predicted WL (r = -0.40, P = .03).

CONCLUSION

Although these variables were not robust predictors, results for at least the PFS suggest there may be value in further exploring this measure using larger sample sizes.

Both Dietary Ratio of n-6 to n-3 Fatty Acids and Total Dietary Lipid Are Positively Associated with Adiposity and Reproductive Health in Zebrafish

BACKGROUND

Controversial findings have been reported in human and animal studies regarding the influence of n-6 (ω-6) to n-3 (ω-3) fatty acid ratios on obesity and health. Two confounding factors may be related to interactions with other dietary lipid components or sex-specific differences in fatty acid metabolism.

OBJECTIVE

This study investigated main and interactive effects of total dietary lipid, ratio of n-6 to n-3 fatty acids, and sex on growth, adiposity, and reproductive health in wild-type zebrafish.

METHODS

Male and female zebrafish (3 wk old) were fed 9 diets consisting of 3 ratios of n-6 to n-3 fatty acids (1.4:1, 5:1, and 9.5:1) varied within 3 total lipid amounts (80, 110, and 140 g/kg) for 16 wk. Data were then collected on growth, body composition (determined by chemical carcass analysis), and female reproductive success (n = 32 breeding events/diet over 4 wk). Main and interactive effects of dietary lipid and sex were evaluated with regression methods. Significant differences within each dietary lipid component were relative to the intercept/reference group (80 g/kg and 1.4:1 ratio).

RESULTS

Dietary lipid and sex interacted in their effects on body weight (P = 0.015), total body length (P = 0.003), and total lipid mass (P = 0.029); thus, these analyses were stratified by sex. Female spawning success decreased as dietary total lipid and fatty acid ratio increased (P = 0.030 and P = 0.026, respectively). While total egg production was not associated with either dietary lipid component, females fed the 5:1 ratio produced higher proportions of viable embryos compared with the 1.4:1 ratio [median (95% CI): 0.915 (0.863, 0.956) vs 0.819 (0.716, 0.876); P < 0.001].

CONCLUSIONS

Further characterization of dietary lipid requirements will help define healthy balances of dietary lipid, while the sex-specific responses to dietary lipid identified in this study may partially explain sex disparities in the development of obesity and its comorbidities.

A randomized cross-over trial to determine the effect of a protein vs. carbohydrate preload on energy balance in ad libitum settings

BACKGROUND

Although high protein diets have been tested in controlled environments for applications to weight management, it is not understood if adding high protein foods to the diet would impact ad libitum energy balance in the absence of other lifestyle changes.

METHODS

This double-blinded randomized crossover trial compared the effects of a protein shake (PS) to a carbohydrate shake (CS), consumed prior to each major meal to equate to 20% of total energy needs over the course of the day, on energy balance over two 5-day treatment periods in healthy adults with BMI 20-30 kg/m2. Tri-axial accelerometers estimated physical activity energy expenditure. Ad libitum energy intake was measured in a laboratory kitchen.

RESULTS

Energy balance was positive during both treatment periods but was not different between periods. There were no interactions between treatment and preload caloric dose or treatment and BMI status on energy balance. Satiety ratings did not differ for any pairwise comparisons between treatment and caloric dose. Controlling for gender and basal metabolic rate, thermic effect of food was greater for PS than CS.

CONCLUSIONS

Preload periods significantly altered the macronutrient composition of the overall diet. This study found limited evidence that carbohydrate or protein preloads have differential effects on energy balance in short-term ad libitum settings.

TRIAL REGISTRATION

This trial was pre-registered on clinicaltrials.gov as NCT02613065 on 11/30/2015.

Childhood obesity intervention studies: A narrative review and guide for investigators, authors, editors, reviewers, journalists, and readers to guard against exaggerated effectiveness claims

Being able to draw accurate conclusions from childhood obesity trials is important to make advances in reversing the obesity epidemic. However, obesity research sometimes is not conducted or reported to appropriate scientific standards. To constructively draw attention to this issue, we present 10 errors that are commonly committed, illustrate each error with examples from the childhood obesity literature, and follow with suggestions on how to avoid these errors. These errors are as follows: using self-reported outcomes and teaching to the test; foregoing control groups and risking regression to the mean creating differences over time; changing the goal posts; ignoring clustering in studies that randomize groups of children; following the forking paths, subsetting, p-hacking, and data dredging; basing conclusions on tests for significant differences from baseline; equating "no statistically significant difference" with "equally effective"; ignoring intervention study results in favor of observational analyses; using one-sided testing for statistical significance; and stating that effects are clinically significant even though they are not statistically significant. We hope that compiling these errors in one article will serve as the beginning of a checklist to support fidelity in conducting, analyzing, and reporting childhood obesity research.

Immune system stimulation induced by porcine reproductive and respiratory syndrome virus alters plasma free amino acid flux and dietary nitrogen utilization in starter pigs1

Changes in plasma free amino acid (AA) flux reflect the modification of AA metabolism in different metabolic states. Infectious diseases repartition AA away from protein retention toward processes involved in immune defense, thus impacting AA utilization in pigs. The current study sought to evaluate the effects of disease induced by a live pathogen on plasma free AA flux and whole-body nitrogen (N) utilization. Twenty gilts (BW 9.4 ± 0.9 kg) were surgically catheterized into the jugular vein, individually housed in metabolism crates, and feed-restricted (550 g/d). Intramuscular inoculation of a live field strain of porcine reproductive and respiratory syndrome virus (PRRSV) was used to induce disease. Whole-body N-balance was conducted across 3 d both before PRRSV inoculation (PRRSV-) and also after PRRSV inoculation (PRRSV+). At the end of each N-balance period, a bolus dose of a labeled [U-13C, U-15N]-AA mixture (Ile, Leu, Lys, Met, Phe, Thr, Trp, Val, and Gln) was infused intravenously, followed by serial blood collection for measurement of isotopic enrichment. A double exponential model was fitted with plasma enrichment data for each pig and each AA, and equation parameters were used to estimate plasma free AA flux and pool size. Apparent ileal digestibility (AID) of dietary N was determined using the slaughter technique and an indigestible marker. Blood chemistry, hematology, body temperature, and serum viremia indicated that PRRSV induced effective immune response in pigs (P < 0.05). Challenge with PRRSV reduced the AID of N (P < 0.05), but had no effect on apparent total tract digestibility of dietary energy (P = 0.12). Plasma flux (µmol/kg BW/h) for Met and Thr was increased by PRRSV infection (P < 0.05). A strong tendency of increased Val flux was observed in PRRSV+ pigs (P = 0.06). Infection with PRRSV increased the pool size for Lys, Met, Thr, Trp, Leu, Val, and Gln (P < 0.05). Collectively, these results suggest that PRRSV alters the utilization of dietary N and AA flux, as well as pool size, in growing pigs. The increase in Thr and Met flux in PRRSV+ pigs may be associated with enhanced utilization of these AA for the synthesis of immune system metabolites and increased catabolism of these AA. Thus, dietary Met, Thr, and Val requirements may increase in pigs infected with PRRSV, relative to the requirements for other AA.

mHealth Improved Fruit and Vegetable Accessibility and Intake in Young Children

OBJECTIVE

To explore the potential of mHealth using smartphones to improve fruit and vegetable intake in children.

DESIGN

A 10-week randomized control and intervention pilot study.

SETTING

Story time sessions at local libraries.

PARTICIPANTS

A convenience sample of 30 parents and children (aged 3-8 years).

INTERVENTION

Delivery of nutrition intervention through the mobile Jump2Health website, Facebook posts, and text messages.

MAIN OUTCOME MEASURES

Electronic food photos of children's meals and snacks, 10-question survey related to fruit and vegetable consumption, reflectance spectroscopy via Veggie Meter to measure skin carotenoid levels, body mass index percentiles, and a mobile learning survey.

ANALYSIS

Descriptive statistics and Wilcoxon matched-pairs signed-rank test.

RESULTS

Veggie Meter values for children and parents showed significant week × treatment interactions in the intervention group compared with the control group for both children (P < .001 and parents (P < .001).

CONCLUSIONS AND IMPLICATIONS

This pilot study offers a potentially effective program including a mobile Web site, social media, and test message components to increase fruit and vegetable intake of young children.

Immune system stimulation induced by Escherichia coli lipopolysaccharide alters plasma free amino acid flux and dietary nitrogen utilization in growing pigs

Changes in plasma free AA flux reflect the modification of AA metabolism in different metabolic states. Immune system stimulation (ISS) in growing pigs may redistribute AA from protein retention towards processes involved in the immune response, thus impacting AA utilization. The aim of the current study was to evaluate the effect of ISS on whole-body nitrogen (N) utilization and the kinetics of plasma free AA. Ten gilts (BW 9.4 ± 1.1 kg) were surgically fitted with jugular vein catheters, individually housed in metabolism crates, and feed-restricted (550 g/d). Repeated intramuscular injections of increasing amounts of Escherichia coli lipopolysaccharide (LPS) were used to induce ISS (30 and 36 µg/kg BW, given 48 h apart). Whole-body N-balance was determined for 3-d before ISS (ISS-) and 3-d during ISS (ISS+). At the end of each N-balance period, a bolus dose of labeled [U-13C, U-15N]-AA mixture (Ile, Leu, Lys, Met, Phe, Thr, Trp, Val, and Gln) was infused intravenously, followed by serial blood collection for determination of isotopic enrichment. A double exponential model was fitted with plasma enrichment data for each pig and each AA, and equation parameters were used to estimate plasma-free AA flux and pool size. Apparent ileal digestibility (AID) of N was determined using the slaughter technique and an indigestible marker. Blood samples were collected before and 76-h after the initiation of ISS and assayed for hematology and blood chemistry. Body temperature (BT) was monitored during the course of study. Blood chemistry, hematology, and BT results indicated that LPS induced effective ISS in pigs (P < 0.05). ISS tended to reduce N retention (P = 0.09) and the N retention-to-N intake ratio (P = 0.08). Apparent total tract digestibility of dietary energy and AID of N were reduced by ISS (P < 0.05). Plasma flux (µmol/kg BW/h) for Ile and Phe was reduced by ISS (P < 0.05). Strong tendencies for decreased Lys flux and N retention were observed in ISS pigs (P < 0.10). ISS increased the pool size for Leu but reduced the pool size for Ile (P < 0.05). Collectively, these results suggest that ISS alters the utilization of dietary N and AA flux, as well as pool size in growing pigs. The decrease in Lys, Phe, and Ile flux during ISS may be attributed to a reduction in whole-body protein synthesis or decreased catabolism of these AA. Relative to other AA, dietary Lys, Phe, and Ile requirements may decrease in ISS pigs.

Obesity, adipocyte hypertrophy, fasting glucose, and resistin are potential contributors to nonalcoholic fatty liver disease in South Asian women

Purpose: Nonalcoholic fatty liver disease (NAFLD) is often referred to as the hepatic manifestation of the metabolic syndrome. The relationship between body weight, NAFLD, and insulin resistance is not well characterized in humans. Additionally, it is unclear why South Asians develop these complications at lower levels of obesity compared to their Western counterparts. Patients and methods: To address this question, we performed a cross-sectional study using a convenience sample of Sri Lankan adult females (n=34) and collected anthropometric data, adipose tissue specimens (for histology), and fasted serum samples (for metabolic and inflammatory markers). Hepatic steatosis was assessed by ultrasound scanning and used to classify participants as NAFL 0, NAFL 1, and NAFL 2. Results: Waist circumference significantly increased with increasing NAFL grade. Participants with NAFL had significantly higher body mass index, hip circumference, and fasting plasma glucose, as well as a higher mean adipocyte area in both abdominal subcutaneous and visceral areas, indicating a higher degree of adipocyte hypertrophy associated with fatty liver. There were, however, no differences in measures of dyslipidemia. Of the multiple adipokines measured, resistin was the only proinflammatory adipokine significantly elevated in NAFL 2. Conclusion: These findings indicate that measures of adiposity, fasting serum glucose, and resistin may be important indicators of NAFLD in South Asian women.

Roux-en-Y gastric bypass surgery alters serum metabolites and fatty acids in patients with morbid obesity

AIM

Bariatric surgery induces significant weight loss, increases insulin sensitivity, and reduces mortality, but the underlying mechanisms are not clear. It was hypothesized that Roux-en-Y gastric bypass (RYGB) surgery improves metabolic profile along with weight loss. The objective of this pilot study was to evaluate changes in serum metabolites and fatty acids (FA) at 2 weeks and 6 months after RYGB.

MATERIALS AND METHODS

Serum samples were collected pre-surgery, at 2 weeks and 6 months post-surgery from 20 patients undergoing RYGB surgery. Serum non-esterified free FA (NEFA) were measured. Serum metabolites and FA were measured using nuclear magnetic resonance spectroscopy and improved direct fatty acid methyl ester synthesis and the gas chromatography/mass spectrometry method, respectively, in subjects who completed follow-up at 6 months (n = 8).

RESULTS

Mean (standard deviation) percent total weight loss was 6.70% (1.7) and 24.91% (6.63) at 2 weeks (n = 15) and 6 months (n = 8) post-surgery, respectively. NEFA were significantly reduced at 6 months post-surgery (P = 0.001, n = 8). Serum branched chain amino acids, 2-aminobutyrate, butyrate, 2-hydroxybutyrate, 3-hydroxybutyrate, acetone, 2-methylglutarate, and 2-oxoisocaproate were significantly reduced, while serum alanine, glycine, pyruvate, and taurine were significantly elevated at 6 months post-surgery compared with pre-surgery (n = 8, P < 0.05). Also, serum FA C10:0, C13:0, C14:0, C15:0, and C18:0 increased significantly (n = 8, P < 0.05) by 6 months post-surgery.

CONCLUSIONS

Changes in serum metabolites and FA at 6 months post-RYGB surgery in this pilot study with limited number of participants are suggestive of metabolic improvement; larger studies are warranted for confirmation.

Subjective social status is associated with compensation for large meals - A prospective pilot study

OBJECTIVES

Subjective social status (SSS) is known to be inversely associated with obesity. Our objective was to determine if SSS is associated with eating behaviors that would predispose to weight gain, specifically, with inadequate compensation for excess energy consumed during a single large meal. Therefore, we conducted a pilot study to determine the association of SSS with 24-h energy balance, 24-h and post-lunch energy intake, changes in body composition and changes in adjusted resting energy expenditure on days when a high-energy lunch was consumed in free-living human subjects.

METHOD

Female participants (7 normal weight and 10 overweight) consumed 60% of' estimated 24-h energy requirements as a lunchtime meal in the laboratory for 14 days. Subjective social status was measured at baseline using the MacArthur Scale. Remote Food Photography Method was used to record food intake outside of the lab on days 1-2, 7-8, and 12-13. Associations of 24-h energy balance, 24-h and post-lunch energy intake, changes in adjusted resting energy expenditure and changes in percent body fat (measured by dual x-ray absorptiometry) with SSS were studied.

RESULTS

Mean (standard deviation) age and BMI were 36.29 (8.25) years and 26.43 (2.32) kg/m², respectively. Lower SSS was significantly associated with positive energy balance (p for trend 0.002), and higher post-lunch energy intake (p = 0.02) when controlled for age and initial body mass index.

CONCLUSIONS

Our pilot data show that lower SSS is associated with higher post-lunch energy intake, which is indicative of poor energy compensation following a large meal. Over a longer time period, this could result in fat mass gain. Studies that are of longer duration and well-powered are warranted to confirm our findings.

The effect of skin-to-skin care on cerebral oxygenation during nasogastric feeding of preterm infants

AIM

To describe cerebral oxygenation during gavage feeding of preterm infants during incubator and skin-to-skin care.

METHODS

Further analysis of data from two crossover studies comparing cerebral oxygenation, heart rate and oxygen saturation during skin-to-skin care with incubator care. Data were analysed in three epochs; 10 minutes prefeed, during-feed and 10 minutes postfeed. Measurements from infants fed during incubator care were compared with those obtained during skin-to-skin care.

RESULTS

In 39 infants [median (IQR) 27.8 (26.1-30.0) weeks' gestation], there was no difference in cerebral oxygenation between pre-, during- and postfeed. Heart rate increased by three beats per minute postfeed compared with during-feed. Twenty infants received two gavage feeds, one feed in the incubator and another during skin-to-skin care. There was no difference in cerebral oxygenation and heart rate; peripheral oxygen saturation decreased by 3% during feeding whilst skin-to-skin care compared with feeding in the incubator.

CONCLUSION

Cerebral oxygenation remained stable before, during and after gavage feeding in an incubator and during skin-to-skin care. The small decrease in oxygen saturation whilst receiving gavage feeding during skin-to-skin care is unlikely to be clinically important, providing reassurance that preterm infants maintain physiological stability during skin-to-skin care.

Social status and energy intake: a randomized controlled experiment

While the inverse association between socioeconomic status (SES) and obesity in high gross domestic product countries is well established using observational data, the extent to which the association is due to a true causal effect of SES and, if so, the mechanisms of this effect remain incompletely known. To assess the influence of social status on obesity via energy intake, we randomized individuals to a higher or lower social status and observed subsequent energy intake. College students between the ages of 18 and 25 were randomized to social status and were operationalized as being a leader or follower in a partner activity as purportedly determined by a (bogus) test of leadership ability. Investigators were blinded to treatment assignment. Immediately after being told their leadership assignment, paired participants were provided with platters of food. Energy intake was objectively measured in kilocalories (kcal) consumed, and paired t-tests were used to test for significant differences in intake between leaders and followers. A total of 60 participants were included in the final analysis (males = 28, females = 32). Overall, no difference in energy intake was observed between leaders and followers, consuming an average of 575.3 and 579.8 kcal, respectively (diff = 4.5 kcal, P = 0.94). The null hypothesis of no effect of social status, operationalized as assignment to a leadership position in a small-group activity, on energy intake was not rejected.

Changes in pediatric waist circumference percentiles despite reported pediatric weight stabilization in the United States

BACKGROUND

Obesity is a global health concern but the United States has reported a leveling in obesity rates in the pediatric population.

OBJECTIVE

To provide updated waist circumference (WC) percentile values, identify differences across time and discuss differences within the context of reported weight stabilization in a nationally representative sample of American children.

METHODS

Percentiles for WC in self-identified African Americans (AA), European Americans (EA) and Mexican Americans (MA) were obtained from 2009-2014 National Health and Nutrition Examination Survey data (NHANES2014). Descriptive trends across time in 10th, 25th, 50th, 75th and 90th percentile WC distributions were identified by comparing NHANES2012 with previously reported NHANESIII (1988-1994).

RESULTS

WC increased in a monotonic fashion in AA, EA and MA boys and girls. When compared with NHANESIII data, a clear left shift of percentile categories was observed such that values that used to be in the 90th percentile are now in the 85th percentile. Differences in WC were observed in EA and MA boys during a reported period of weight stabilization.

CONCLUSION AND RELEVANCE

WC has changed in the US pediatric population across time, even during times of reported weight stabilization, particularly among children of diverse racial/ethnic backgrounds.

Extended calorie restriction suppresses overall and specific food cravings: a systematic review and a meta-analysis

BACKGROUND

Multiple studies have concluded that calorie restriction for at least 12 weeks is associated with reduced food cravings, while others have shown that calorie restriction may increase food cravings. We addressed this ambiguity in a systematic review and meta-analysis.

METHODS

We searched for studies conducted on subjects with obesity, implemented calorie restriction for at least 12 weeks and measured food cravings pre-intervention and post-intervention. Our final eight studies mostly used the Food Craving Inventory. Other comparable methods were converted to a similar scale. We used the duration ≥12 weeks, but closest to 16 weeks for studies with multiple follow-ups and performed DerSimonian-Laird random-effects meta-analyses using the 'metafor' package in r software.

RESULTS

Despite heterogeneity across studies, we observed reductions in pooled effects for overall food cravings (-0.246 [-0.490, -0.001]) as well as cravings for sweet (-0.410 [-0.626, -0.194]), high-fat (-0.190 [-0.343, -0.037]), starchy (-0.288 [-0.517, -0.058]) and fast food (-0.340 [-0.633, -0.048]) in the meta-analysis. Baseline body weight, type of intervention, duration, sample size and percentage of female subjects explained the heterogeneity.

CONCLUSIONS

Calorie restriction is associated with reduced food cravings supporting a de-conditioning model of craving reductions. Our findings should ease the minds of clinicians concerned about increased cravings in patients undergoing calorie restriction interventions.

Observational research rigour alone does not justify causal inference

BACKGROUND

Differing opinions exist on whether associations obtained in observational studies can be reliable indicators of a causal effect if the observational study is sufficiently well controlled and executed.

MATERIALS AND METHODS

To test this, we conducted two animal observational studies that were rigorously controlled and executed beyond what is achieved in studies of humans. In study 1, we randomized 332 genetically identical C57BL/6J mice into three diet groups with differing food energy allotments and recorded individual self-selected daily energy intake and lifespan. In study 2, 60 male mice (CD1) were paired and divided into two groups for a 2-week feeding regimen. We evaluated the association between weight gain and food consumption. Within each pair, one animal was randomly assigned to an S group in which the animals had free access to food. The second paired animal (R group) was provided exactly the same diet that their S partner ate the day before.

RESULTS

In study 1, across all three groups, we found a significant negative effect of energy intake on lifespan. However, we found a positive association between food intake and lifespan among the ad libitum feeding group: 29·99 (95% CI: 8·2-51·7) days per daily kcal. In study 2, we found a significant (P = 0·003) group (randomized vs. self-selected)-by-food consumption interaction effect on weight gain.

CONCLUSION

At least in nutrition research, associations derived from observational studies may not be reliable indicators of causal effects, even with the most rigorous study designs achievable.

Rigorous control conditions diminish treatment effects in weight loss-randomized controlled trials

BACKGROUND

It has not been established whether control conditions with large weight losses (WLs) diminish expected treatment effects in WL or prevention of weight gain (PWG)-randomized controlled trials (RCTs).

SUBJECTS/METHODS

We performed a meta-analysis of 239 WL/PWG RCTs that include a control group and at least one treatment group. A maximum likelihood meta-analysis framework was used to model and understand the relationship between treatment effects and control group outcomes.

RESULTS

Under the informed model, an increase in control group WL of 1 kg corresponds with an expected shrinkage of the treatment effect by 0.309 kg (95% confidence interval (-0.480, -0.138), P=0.00081); this result is robust against violations of the model assumptions.

CONCLUSIONS

We find that control conditions with large WLs diminish expected treatment effects. Our investigation may be helpful to clinicians as they design future WL/PWG studies.

Assessing the tongue colour of newly born infants may help to predict the need for supplemental oxygen in the delivery room

AIM

It takes several minutes for infants to become pink after birth. Preductal oxygen saturation (SpO2) measurements are used to guide the delivery of supplemental oxygen to newly born infants, but pulse oximetry is not available in many parts of the world. We explored whether the pinkness of an infant's tongue provided a useful indication that supplemental oxygen was required.

METHODS

This was a prospective observational study of infants delivered by Caesarean section. Simultaneous recording of SpO2 and visual assessment of whether the tongue was pink or not was made at 1-7 and 10 min after birth.

RESULTS

The 38 midwives and seven paediatric trainees carried out 271 paired assessments on 68 infants with a mean (SD) birthweight of 3214 (545) grams and gestational age of 38 (2) weeks. When the infant did not have a pink tongue, this predicted SpO2 of <70% with a sensitivity of 26% and a specificity of 96%.

CONCLUSION

Tongue colour was a specific but insensitive sign that indicated when SpO2 was <70%. When the tongue is pink, it is likely that an infant has an SpO2 of more than 70% and does not require supplemental oxygen.

Double sampling with multiple imputation to answer large sample meta-research questions: introduction and illustration by evaluating adherence to two simple CONSORT guidelines

Background: Meta-research can involve manual retrieval and evaluation of research, which is resource intensive. Creation of high throughput methods (e.g., search heuristics, crowdsourcing) has improved feasibility of large meta-research questions, but possibly at the cost of accuracy.

Objective: To evaluate the use of double sampling combined with multiple imputation (DS + MI) to address meta-research questions, using as an example adherence of PubMed entries to two simple consolidated standards of reporting trials guidelines for titles and abstracts.

Methods: For the DS large sample, we retrieved all PubMed entries satisfying the filters: RCT, human, abstract available, and English language (n = 322, 107). For the DS subsample, we randomly sampled 500 entries from the large sample. The large sample was evaluated with a lower rigor, higher throughput (R_LOT_HI) method using search heuristics, while the subsample was evaluated using a higher rigor, lower throughput (R_HIT_LO) human rating method. Multiple imputation of the missing-completely at-random R_HIT_LO data for the large sample was informed by: R_HIT_LO data from the subsample; R_LOT_HI data from the large sample; whether a study was an RCT; and country and year of publication.

Results: The R_HIT_LO and R_LOT_HI methods in the subsample largely agreed (phi coefficients: title = 1.00, abstract = 0.92). Compliance with abstract and title criteria has increased over time, with non-US countries improving more rapidly. DS + MI logistic regression estimates were more precise than subsample estimates (e.g., 95% CI for change in title and abstract compliance by year: subsample R_HIT_LO 1.050–1.174 vs. DS + MI 1.082–1.151). As evidence of improved accuracy, DS + MI coefficient estimates were closer to R_HIT_LO than the large sample R_LOT_HI.

Conclusion: Our results support our hypothesis that DS + MI would result in improved precision and accuracy. This method is flexible and may provide a practical way to examine large corpora of literature.

Extending information retrieval methods to personalized genomic-based studies of disease

Genomic-based studies of disease now involve diverse types of data collected on large groups of patients. A major challenge facing statistical scientists is how best to combine the data, extract important features, and comprehensively characterize the ways in which they affect an individual’s disease course and likelihood of response to treatment. We have developed a survival-supervised latent Dirichlet allocation (survLDA) modeling framework to address these challenges. Latent Dirichlet allocation (LDA) models have proven extremely effective at identifying themes common across large collections of text, but applications to genomics have been limited. Our framework extends LDA to the genome by considering each patient as a “document” with “text” detailing his/her clinical events and genomic state. We then further extend the framework to allow for supervision by a time-to-event response. The model enables the efficient identification of collections of clinical and genomic features that co-occur within patient subgroups, and then characterizes each patient by those features. An application of survLDA to The Cancer Genome Atlas ovarian project identifies informative patient subgroups showing differential response to treatment, and validation in an independent cohort demonstrates the potential for patient-specific inference.

Microarray-based characterization of differential gene expression during vocal fold wound healing in rats

The vocal fold (VF) mucosa confers elegant biomechanical function for voice production but is susceptible to scar formation following injury. Current understanding of VF wound healing is hindered by a paucity of data and is therefore often generalized from research conducted in skin and other mucosal systems. Here, using a previously validated rat injury model, expression microarray technology and an empirical Bayes analysis approach, we generated a VF-specific transcriptome dataset to better capture the system-level complexity of wound healing in this specialized tissue. We measured differential gene expression at 3, 14 and 60 days post-injury compared to experimentally naïve controls, pursued functional enrichment analyses to refine and add greater biological definition to the previously proposed temporal phases of VF wound healing, and validated the expression and localization of a subset of previously unidentified repair- and regeneration-related genes at the protein level. Our microarray dataset is a resource for the wider research community and has the potential to stimulate new hypotheses and avenues of investigation, improve biological and mechanistic insight, and accelerate the identification of novel therapeutic targets.

Unique aspects of fiber degradation by the ruminal ethanologen Ruminococcus albus 7 revealed by physiological and transcriptomic analysis

BACKGROUND

Bacteria in the genus Ruminococcus are ubiquitous members of the mammalian gastrointestinal tract. In particular, they are important in ruminants where they digest a wide range of plant cell wall polysaccharides. For example, Ruminococcus albus 7 is a primary cellulose degrader that produces acetate usable by its bovine host. Moreover, it is one of the few organisms that ferments cellulose to form ethanol at mesophilic temperatures in vitro. The mechanism of cellulose degradation by R. albus 7 is not well-defined and is thought to involve pilin-like proteins, unique carbohydrate-binding domains, a glycocalyx, and cellulosomes. Here, we used a combination of comparative genomics, fermentation analyses, and transcriptomics to further clarify the cellulolytic and fermentative potential of R. albus 7.

RESULTS

A comparison of the R. albus 7 genome sequence against the genome sequences of related bacteria that either encode or do not encode cellulosomes revealed that R. albus 7 does not encode for most canonical cellulosomal components. Fermentation analysis of R. albus 7 revealed the ability to produce ethanol and acetate on a wide range of fibrous substrates in vitro. Global transcriptomic analysis of R. albus 7 grown at identical dilution rates on cellulose and cellobiose in a chemostat showed that this bacterium, when growing on cellulose, utilizes a carbohydrate-degrading strategy that involves increased transcription of the rare carbohydrate-binding module (CBM) family 37 domain and the tryptophan biosynthetic operon.

CONCLUSIONS

Our data suggest that R. albus 7 does not use canonical cellulosomal components to degrade cellulose, but rather up-regulates the expression of CBM37-containing enzymes and tryptophan biosynthesis. This study contributes to a revised model of carbohydrate degradation by this key member of the rumen ecosystem.

Predicting adult weight change in the real world: a systematic review and meta-analysis accounting for compensatory changes in energy intake or expenditure

BACKGROUND

Public health and clinical interventions for obesity in free-living adults may be diminished by individual compensation for the intervention. Approaches to predict weight outcomes do not account for all mechanisms of compensation, so they are not well suited to predict outcomes in free-living adults. Our objective was to quantify the range of compensation in energy intake or expenditure observed in human randomized controlled trials (RCTs).

METHODS

We searched multiple databases (PubMed, CINAHL, SCOPUS, Cochrane, ProQuest, PsycInfo) up to 1 August 2012 for RCTs evaluating the effect of dietary and/or physical activity interventions on body weight/composition.

INCLUSION CRITERIA

subjects per treatment arm ≥5; ≥1 week intervention; a reported outcome of body weight/body composition; the intervention was either a prescribed amount of over- or underfeeding and/or supervised or monitored physical activity was prescribed; ≥80% compliance; and an objective method was used to verify compliance with the intervention (for example, observation and electronic monitoring). Data were independently extracted and analyzed by multiple reviewers with consensus reached by discussion. We compared observed weight change with predicted weight change using two models that predict weight change accounting only for metabolic compensation.

FINDINGS

Twenty-eight studies met inclusion criteria. Overfeeding studies indicate 96% less weight gain than expected if no compensation occurred. Dietary restriction and exercise studies may result in up to 12-44% and 55-64% less weight loss than expected, respectively, under an assumption of no behavioral compensation.

INTERPRETATION

Compensation is substantial even in high-compliance conditions, resulting in far less weight change than would be expected. The simple algorithm we report allows for more realistic predictions of intervention effects in free-living populations by accounting for the significant compensation that occurs.

Effects of early life exposure to methylmercury in Daphnia pulex on standard and reduced food ration

As a well-known eco-toxicological model organism, Daphnia pulex may also offer advantages in human health research for assessing long-term effects of early life exposures to coupled stressors. Here, we examine consequences of early life exposure to methylmercury (MeHg) under standard and reduced food ration. We exposed Daphnia for 24h in early life to varying concentrations of methylmercury(II) chloride (0, 200, 400, 800 and 1600ng/L) and thereafter kept Daphnia on either a standard or a reduced food ration. The data suggests an additive effect of MeHg concentration and food ration on decreasing lifespan, although MeHg concentration does not affect survival linearly. Food ration and MeHg concentration were predictive of reduced reproduction, and there is some evidence of an interaction (p=0.048). Multi-stressor work in alternative model systems may be useful for prioritizing research, taking into account potential antagonistic, additive or synergistic effects that nutritional status may have on chemical toxicity.

Novel mathematical models for investigating topics in obesity

There is limited insight into the mechanisms, progression, and related comorbidities of obesity through simple modeling tools such as linear regression. Keeping in mind the words of the late George E. P. Box that “all models are wrong, some are useful,” this symposium presented 4 useful mathematical models or methodologic refinements. Presenters placed specific emphasis on how these novel models and methodologies can be applied to further our knowledge of the etiology of obesity.

The precision and accuracy of Nellcor and Masimo oximeters at low oxygen saturations (70%) in newborn lambs

BACKGROUND

Administration of oxygen in the delivery room is informed by oxygen saturation (SpO₂). An oxygen saturation range of 60%-70% is the threshold for administering oxygen in the first minutes after birth. The accuracy of newer generation oximeters to measure SpO₂ has not been compared against the 'gold standard', direct arterial blood oxygen saturation (SaO₂) when SaO₂ is low. The aim of this study was to determine the accuracy and precision of Nellcor and Masimo oximeters to measure SpO₂ when SaO₂ <70%.

METHOD

Prospective observational study in ventilated anaesthetised newborn lambs with an indwelling carotid artery catheter. Ventilation was adjusted to achieve hypoxaemia. Nellcor (Oxi-Max 600 with Max-N sensor) and Masimo (Rad 4 with low noise optical probe (LNOP) sensor) sensors were applied to the right forelimb (preductal). An arterial blood sample was collected at 1-5 min intervals when the animal was hypoxic. The displayed SpO₂ was recorded. We used Bland-Altman analysis to determine precision and accuracy of each oximeter when SaO₂ <70%.

RESULTS

17 lambs were studied, 165 measurements were obtained, 123 were SaO₂ <70%. The mean difference (±1.96 SD) Nellcor SpO₂-SaO₂ when SaO₂ <70% was 17% (-12% to 46%). The mean difference (±1.96 SD) Masimo SpO₂-SaO₂ when SaO2 <70% was 13% (-19% to 45%).

CONCLUSIONS

At SaO₂<70%, both monitors overestimated oxygen saturation (SpO₂) compared with the gold standard. Both oximeters were equally inaccurate when SaO₂ was low.

Self-inflating bags versus T-piece resuscitator to deliver sustained inflations in a preterm lamb model

OBJECTIVE

In neonatal resuscitation, the use of a sustained inflation (SI) may facilitate lung aeration. Previous studies comparing different resuscitation devices have shown that one model of self-inflating bag (SIB) could not deliver an SI. We aimed to compare the delivery of an SI using four SIBs with that of a T-piece.

STUDY DESIGN

In intubated preterm lambs, we compared four models of SIB fitted with a positive end expiratory pressure (PEEP) valve to a T-piece using a gas flow of 8 L/min. Four operators aimed to deliver three SIs of 20 cm H₂O for 30 s. The study was repeated with the PEEP valve removed and again with no flow. We measured duration of SI, average inflation pressure (IP) and analysed the shape of the pressure curves.

RESULTS

204 combinations were analysed. Mean (SD) duration of SI was Ambu 6(2)s, Laerdal 14(8)s, Parker Healthcare 5(1)s, Mayo Healthcare 33(2)s and T-piece 33(1)s. Mean (SD) average IP was Ambu 17(3)cm H₂O, Laerdal 17(3)cm H₂O, Parker Healthcare 12(5)cm H₂O, Mayo Healthcare 21(2)cm H₂O and T-piece 20(0)cm H₂O. Duration of SI and average IP was significantly different between SIBs (all p<0.001). The findings were substantially unchanged when PEEP valve and flow were removed (all p>0.05). Only the Mayo system delivered SIs with duration and average IP not significantly different from the T-piece (p>0.05).

CONCLUSIONS

The performance of the four SIBs tested varied considerably. Some are able to deliver an SI even in the absence of gas flow. This may be useful in a resource-limited setting with no gas supply.

Are high flow nasal cannulae noisier than bubble CPAP for preterm infants?

BACKGROUND

Noise exposure in the neonatal intensive care unit is believed to be a risk factor for hearing loss in preterm neonates. Continuous positive airway pressure (CPAP) devices exceed recommended noise levels. High flow nasal cannulae (HFNC) are an increasingly popular alternative to CPAP for treating preterm infants, but there are no in vivo studies assessing noise production by HFNC.

OBJECTIVE

To study whether HFNC are noisier than bubble CPAP (BCPAP) for preterm infants.

METHODS

An observational study of preterm infants receiving HFNC or BCPAP. Noise levels within the external auditory meatus (EAM) were measured using a microphone probe tube connected to a calibrated digital dosimeter. Noise was measured across a range of frequencies and reported as decibels A-weighted (dBA).

RESULTS

A total of 21 HFNC and 13 BCPAP noise measurements were performed in 21 infants. HFNC gas flows were 2-5 L/min, and BCPAP gas flows were 6-10 L/min with set pressures of 5-7 cm of water. There was no evidence of a difference in average noise levels measured at the EAM: mean difference (95% CI) of -1.6 (-4.0 to 0.9) dBA for HFNC compared to BCPAP. At low frequency (500 Hz), HFNC was mean (95% CI) 3.0 (0.3 to 5.7) dBA quieter than BCPAP. Noise increased with increasing BCPAP gas flow (p=0.007), but not with increasing set pressure. There was a trend to noise increasing with increasing HFNC gas flows.

CONCLUSIONS

At the gas flows studied, HFNC are not noisier than BCPAP for preterm infants.

Reference values for body composition and anthropometric measurements in athletes

BACKGROUND

Despite the importance of body composition in athletes, reference sex- and sport-specific body composition data are lacking. We aim to develop reference values for body composition and anthropometric measurements in athletes.

METHODS

Body weight and height were measured in 898 athletes (264 female, 634 male), anthropometric variables were assessed in 798 athletes (240 female and 558 male), and in 481 athletes (142 female and 339 male) with dual-energy X-ray absorptiometry (DXA). A total of 21 different sports were represented. Reference percentiles (5th, 25th, 50th, 75th, and 95th) were calculated for each measured value, stratified by sex and sport. Because sample sizes within a sport were often very low for some outcomes, the percentiles were estimated using a parametric, empirical Bayesian framework that allowed sharing information across sports.

RESULTS

We derived sex- and sport-specific reference percentiles for the following DXA outcomes: total (whole body scan) and regional (subtotal, trunk, and appendicular) bone mineral content, bone mineral density, absolute and percentage fat mass, fat-free mass, and lean soft tissue. Additionally, we derived reference percentiles for height-normalized indexes by dividing fat mass, fat-free mass, and appendicular lean soft tissue by height squared. We also derived sex- and sport-specific reference percentiles for the following anthropometry outcomes: weight, height, body mass index, sum of skinfold thicknesses (7 skinfolds, appendicular skinfolds, trunk skinfolds, arm skinfolds, and leg skinfolds), circumferences (hip, arm, midthigh, calf, and abdominal circumferences), and muscle circumferences (arm, thigh, and calf muscle circumferences).

CONCLUSIONS

These reference percentiles will be a helpful tool for sports professionals, in both clinical and field settings, for body composition assessment in athletes.