Contrast-specific propensity scores for causal inference with multiple interventions

Existing methods that use propensity scores for heterogeneous treatment effect estimation on non-experimental data do not readily extend to the case of more than two treatment options. In this work, we develop a new propensity score-based method for heterogeneous treatment effect estimation when there are three or more treatment options, and prove that it generates unbiased estimates. We demonstrate our method on a real patient registry of patients in Singapore with diabetic dyslipidemia. On this dataset, our method generates heterogeneous treatment recommendations for patients among three options: Statins, fibrates, and non-pharmacological treatment to control patients' lipid ratios (total cholesterol divided by high-density lipoprotein level). In our numerical study, our proposed method generated more stable estimates compared to a benchmark method based on a multi-dimensional propensity score.

Association of acylcarnitines with maternal cardiometabolic risk factors is defined by chain length: the S-PRESTO study

CONTEXT

Due to the essential role of carnitine as an intermediary in amino acid, carbohydrate and lipid metabolism, a detailed characterization of circulating and urinary carnitine concentrations will aid in elucidating the molecular basis of impaired maternal metabolic flexibility and facilitating timely intervention for expectant mothers.

OBJECTIVE

To investigate the association of maternal plasma and urinary free carnitine and acylcarnitines with cardiometabolic risk factors.

METHODS

LC-MS/MS-based quantification of free carnitine and acylcarnitines (C2-C18) was performed on 765 plasma and 702 urine samples collected at preconception, 26-28 weeks' pregnancy, and three months postpartum in the Singapore PREconception Study of long-Term maternal and child Outcomes (S-PRESTO) cohort study.

RESULTS

Plasma concentrations of free carnitine and acylcarnitines decreased coupled with increased renal clearance in pregnancy compared to preconception and postpartum. Renal clearance of carnitine increased with an increase in pre-pregnancy body mass index (ppBMI) and gestational weight gain. Plasma short-chain acylcarnitines were positively associated with ppBMI, irrespective of the physiological state, while medium- and long-chain acylcarnitines were negatively associated with ppBMI at preconception and postpartum but showed a positive association in pregnancy. Similarly, plasma short-chain acylcarnitines were positively associated with HOMA-IR whereas medium- and long-chain acylcarnitines were negatively associated with HOMA-IR at preconception and in pregnancy. Mothers who developed gestational diabetes mellitus during pregnancy had ∼10% higher plasma propionylcarnitine concentration and ∼18% higher urine tiglylcarnitine concentration compared to mothers with normal glucose metabolism at preconception.

CONCLUSIONS

This study provides the metabolic and physiological basis of maternal carnitine homeostasis, which can be used in assessment of maternal cardiometabolic health at preconception to improve pregnancy outcomes.

A fully convolutional neural network for comprehensive compartmentalization of abdominal adipose tissue compartments in MRI

BACKGROUND

Existing literature has highlighted structural, physiological, and pathological disparities among abdominal adipose tissue (AAT) sub-depots. Accurate separation and quantification of these sub-depots are crucial for advancing our understanding of obesity and its comorbidities. However, the absence of clear boundaries between the sub-depots in medical imaging data has challenged their separation, particularly for internal adipose tissue (IAT) sub-depots. To date, the quantification of AAT sub-depots remains challenging, marked by a time-consuming, costly, and complex process.

PURPOSE

To implement and evaluate a convolutional neural network to enable granular assessment of AAT by compartmentalization of subcutaneous adipose tissue (SAT) into superficial subcutaneous (SSAT) and deep subcutaneous (DSAT) adipose tissue, and IAT into intraperitoneal (IPAT), retroperitoneal (RPAT), and paraspinal (PSAT) adipose tissue.

MATERIAL AND METHODS

MRI datasets were retrospectively collected from Singapore Preconception Study for Long-Term Maternal and Child Outcomes (S-PRESTO: 389 women aged 31.4 ± 3.9 years) and Singapore Adult Metabolism Study (SAMS: 50 men aged 28.7 ± 5.7 years). For all datasets, ground truth segmentation masks were created through manual segmentation. A Res-Net based 3D-UNet was trained and evaluated via 5-fold cross-validation on S-PRESTO data (N = 300). The model's final performance was assessed on a hold-out (N = 89) and an external test set (N = 50, SAMS).

RESULTS

The proposed method enabled reliable segmentation of individual AAT sub-depots in 3D MRI volumes with high mean Dice similarity scores of 98.3%, 97.2%, 96.5%, 96.3%, and 95.9% for SSAT, DSAT, IPAT, RPAT, and PSAT respectively.

CONCLUSION

Convolutional neural networks can accurately sub-divide abdominal SAT into SSAT and DSAT, and abdominal IAT into IPAT, RPAT, and PSAT with high accuracy. The presented method has the potential to significantly contribute to advancements in the field of obesity imaging and precision medicine.

Effect of the COVID-19 pandemic on surgery for indeterminate thyroid nodules (THYCOVID): a retrospective, international, multicentre, cross-sectional study

BACKGROUND

Since its outbreak in early 2020, the COVID-19 pandemic has diverted resources from non-urgent and elective procedures, leading to diagnosis and treatment delays, with an increased number of neoplasms at advanced stages worldwide. The aims of this study were to quantify the reduction in surgical activity for indeterminate thyroid nodules during the COVID-19 pandemic; and to evaluate whether delays in surgery led to an increased occurrence of aggressive tumours.

METHODS

In this retrospective, international, cross-sectional study, centres were invited to participate in June 22, 2022; each centre joining the study was asked to provide data from medical records on all surgical thyroidectomies consecutively performed from Jan 1, 2019, to Dec 31, 2021. Patients with indeterminate thyroid nodules were divided into three groups according to when they underwent surgery: from Jan 1, 2019, to Feb 29, 2020 (global prepandemic phase), from March 1, 2020, to May 31, 2021 (pandemic escalation phase), and from June 1 to Dec 31, 2021 (pandemic decrease phase). The main outcomes were, for each phase, the number of surgeries for indeterminate thyroid nodules, and in patients with a postoperative diagnosis of thyroid cancers, the occurrence of tumours larger than 10 mm, extrathyroidal extension, lymph node metastases, vascular invasion, distant metastases, and tumours at high risk of structural disease recurrence. Univariate analysis was used to compare the probability of aggressive thyroid features between the first and third study phases. The study was registered on ClinicalTrials.gov, NCT05178186.

FINDINGS

Data from 157 centres (n=49 countries) on 87 467 patients who underwent surgery for benign and malignant thyroid disease were collected, of whom 22 974 patients (18 052 [78·6%] female patients and 4922 [21·4%] male patients) received surgery for indeterminate thyroid nodules. We observed a significant reduction in surgery for indeterminate thyroid nodules during the pandemic escalation phase (median monthly surgeries per centre, 1·4 [IQR 0·6-3·4]) compared with the prepandemic phase (2·0 [0·9-3·7]; p<0·0001) and pandemic decrease phase (2·3 [1·0-5·0]; p<0·0001). Compared with the prepandemic phase, in the pandemic decrease phase we observed an increased occurrence of thyroid tumours larger than 10 mm (2554 [69·0%] of 3704 vs 1515 [71·5%] of 2119; OR 1·1 [95% CI 1·0-1·3]; p=0·042), lymph node metastases (343 [9·3%] vs 264 [12·5%]; OR 1·4 [1·2-1·7]; p=0·0001), and tumours at high risk of structural disease recurrence (203 [5·7%] of 3584 vs 155 [7·7%] of 2006; OR 1·4 [1·1-1·7]; p=0·0039).

INTERPRETATION

Our study suggests that the reduction in surgical activity for indeterminate thyroid nodules during the COVID-19 pandemic period could have led to an increased occurrence of aggressive thyroid tumours. However, other compelling hypotheses, including increased selection of patients with aggressive malignancies during this period, should be considered. We suggest that surgery for indeterminate thyroid nodules should no longer be postponed even in future instances of pandemic escalation.

FUNDING

None.

Multidimensional conservation analysis decodes the expression of conserved long noncoding RNAs

Although long noncoding RNAs (lncRNAs) experience weaker evolutionary constraints and exhibit lower sequence conservation than coding genes, they can still conserve their features in various aspects. Here, we used multiple approaches to systemically evaluate the conservation between human and mouse lncRNAs from various dimensions including sequences, promoter, global synteny, and local synteny, which led to the identification of 1,731 conserved lncRNAs with 427 high-confidence ones meeting multiple criteria. Conserved lncRNAs, compared with non-conserved ones, generally have longer gene bodies, more exons and transcripts, stronger connections with human diseases, and are more abundant and widespread across different tissues. Transcription factor (TF) profile analysis revealed a significant enrichment of TF types and numbers in the promoters of conserved lncRNAs. We further identified a set of TFs that preferentially bind to conserved lncRNAs and exert stronger regulation on conserved than non-conserved lncRNAs. Our study has reconciled some discrepant interpretations of lncRNA conservation and revealed a new set of transcriptional factors ruling the expression of conserved lncRNAs.

Endothelial Damage Arising From High Salt Hypertension Is Elucidated by Vascular Bed Systematic Profiling

BACKGROUND

Considerable evidence links dietary salt intake with the development of hypertension, left ventricular hypertrophy, and increased risk of stroke and coronary heart disease. Despite extensive epidemiological and basic science interrogation of the relationship between high salt (HS) intake and blood pressure, it remains unclear how HS impacts endothelial cell (EC) and vascular structure in vivo. This study aims to elucidate HS-induced vascular pathology using a differential systemic decellularization in vivo approach.

METHODS

We performed systematic molecular characterization of the endothelial glycocalyx and EC proteomes in mice with HS (8%) diet-induced hypertension versus healthy control animals. Isolation of eGC and EC compartments was achieved using differential systemic decellularization in vivo methodology. Altered protein expression in hypertensive compared to normal mice was characterized by liquid chromatography tandem mass spectrometry. Proteomic results were validated using functional assays, microscopic imaging, and histopathologic evaluation.

RESULTS

Proteomic analysis revealed a significant downregulation of eGC and associated proteins in HS diet-induced hypertensive mice (among 1696 proteins identified in this group, 723 were markedly decreased in abundance, while only 168 were increased in abundance. Bioinformatic analysis indicated substantial derangement of the eGC layer, which was subsequently confirmed by fluorescent and electron microscopy assessment of vessel damage ex vivo. In the EC fraction, HS-induced hypertension significantly altered protein mediators of contractility, metabolism, mechanotransduction, renal function, and the coagulation cascade. In particular, we observed dysregulation of integrin subunits α2, α2b, and α5, which was associated with arterial wall inflammation and substantial infiltration of CD68+ monocyte-macrophages. Consequently, HS-induced hypertensive mice also displayed reduced vascular integrity of multiple organs including lungs, kidneys, and heart.

CONCLUSIONS

These findings provide novel molecular insight into HS-induced structural changes in eGC and EC composition that may increase cardiovascular risk and potentially guide the development of new diagnostics and therapeutic interventions.

Prediction of subclinical atherosclerosis in low Framingham risk score individuals by using the metabolic syndrome criteria and insulin sensitivity index

Background

Subclinical atherosclerosis can be present in individuals with an optimal cardiovascular risk factor profile. Traditional risk scores such as the Framingham risk score do not adequately capture risk stratification in low-risk individuals. The aim of this study was to determine if markers of metabolic syndrome and insulin resistance can better stratify low-risk individuals.

Methods

A cross-sectional study of 101 healthy participants with a low Framingham risk score and no prior morbidities was performed to assess prevalence of subclinical atherosclerosis using computed tomography (CT) and ultrasound. Participants were compared between groups based on Metabolic Syndrome (MetS) and Insulin-Sensitivity Index (ISI-cal) scores.

Results

Twenty three individuals (23%) had subclinical atherosclerosis with elevated CT Agatston score ≥1. Presence of both insulin resistance (ISI-cal <9.23) and fulfillment of at least one metabolic syndrome criterion denoted high risk, resulting in significantly improved AUC (0.706 95%CI 0.588–0.822) over the Framingham risk score in predicting elevated CT Agatston score ≥1, with net reclassification index of 50.9 ± 23.7%. High-risk patients by the new classification also exhibited significantly increased carotid intima thickness.

Conclusions

The overlap of insulin resistance and presence of ≥1 criterion for metabolic syndrome may play an instrumental role in identifying traditionally low-risk individuals predisposed to future risk of atherosclerosis and its sequelae.

Minor perturbations of thyroid homeostasis and major cardiovascular endpoints—Physiological mechanisms and clinical evidence

It is well established that thyroid dysfunction is linked to an increased risk of cardiovascular morbidity and mortality. The pleiotropic action of thyroid hormones strongly impacts the cardiovascular system and affects both the generation of the normal heart rhythm and arrhythmia. A meta-analysis of published evidence suggests a positive association of FT4 concentration with major adverse cardiovascular end points (MACE), but this association only partially extends to TSH. The risk for cardiovascular death is increased in both subclinical hypothyroidism and subclinical thyrotoxicosis. Several published studies found associations of TSH and FT4 concentrations, respectively, with major cardiovascular endpoints. Both reduced and elevated TSH concentrations predict the cardiovascular risk, and this association extends to TSH gradients within the reference range. Likewise, increased FT4 concentrations, but high-normal FT4 within its reference range as well, herald a poor outcome. These observations translate to a monotonic and sensitive effect of FT4 and a U-shaped relationship between TSH and cardiovascular risk. Up to now, the pathophysiological mechanism of this complex pattern of association is poorly understood. Integrating the available evidence suggests a dual etiology of elevated FT4 concentration, comprising both ensuing primary hypothyroidism and a raised set point of thyroid function, e. g. in the context of psychiatric disease, chronic stress and type 2 allostatic load. Addressing the association between thyroid homeostasis and cardiovascular diseases from a systems perspective could pave the way to new directions of research and a more personalized approach to the treatment of patients with cardiovascular risk.

Brown adipose tissues mediate the metabolism of branched chain amino acids during the transitioning from hyperthyroidism to euthyroidism (TRIBUTE)

Both hyperthyroidism and elevated plasma branched chain amino acids (BCAA) are associated with insulin resistance. BCAA utilization and clearance relative to thyroid status changes remains unclear. We investigate amino acids changes, specifically BCAA, during the transition from hyperthyroidism to euthyroidism, and the impact of active brown adipose tissue (BAT) on the metabolic effects of BCAA. Newly diagnosed Graves’ disease participants were recruited. Hyperthyroidism was treated via a titration dosing regimen of thionamide anti-thyroid drug to establish euthyroidism over 12–24 weeks. All underwent energy expenditure (EE) measurement within a chamber calorimeter, 18F-fluorodeoxyglucose (18F-FDG) positron-emission tomography/magnetic resonance (PET/MR) imaging and plasma amino acids measurement during hyperthyroidism and euthyroidism. PET BAT maximum standardized uptake value (SUVmax), SUVmean and MR supraclavicular fat fraction (FF) quantified BAT activity. Twenty-two patients completed the study. Plasma BCAA level was significantly reduced in BAT-positive but not in BAT-negative patients during the transition from hyperthyroidism to euthyroidism. Plasma valine but not leucine and isoleucine correlated positively with insulin and HOMA-IR in hyperthyroidism. Plasma valine, leucine and isoleucine correlated with insulin and HOMA-IR in euthyroidism. Plasma valine correlated with insulin and HOMA-IR in BAT-negative but not in BAT-positive participants in both hyperthyroid and euthyroid state. However, the change (i.e. decrease) in plasma valine concentration from hyperthyroid to euthyroid state was affected by BAT-status. BAT utilizes and promotes BCAA plasma clearance from hyperthyroid to euthyroid state. Active BAT can potentially reduce circulating BCAA and may help to ameliorate insulin resistance and improve metabolic health.

Clinical trial registration: The trial was registered at clinicaltrials.gov as NCT03064542.

Clinical- and omics-based models of subclinical atherosclerosis in healthy Chinese adults: a cross-sectional exploratory study

BACKGROUND

Classical risk factors, such as fasting cholesterol, blood pressure (BP), and diabetes status are used today to predict the risk of developing cardiovascular disease (CVD). However, accurate prediction remains limited, particularly in low-risk groups such as women and younger individuals. Growing evidence suggests that biomarker concentrations following consumption of a meal challenge are better and earlier predictors of disease development than biomarker concentrations.

OBJECTIVE

To test the hypothesis that postprandial responses of circulating biomarkers differ between healthy subjects with and without subclinical atherosclerosis (SA) in an Asian population at low risk of coronary artery disease (CAD).

METHODS

One hundred healthy Chinese subjects (46 women, 54 men) completed the study. Subjects consumed a mixed-meal test and 164 blood biomarkers were analyzed over 6 h by using a combination of chemical and NMR techniques. Models were trained using different methodologies (including logistic regression, elastic net, random forest, sparse partial least square) on a random 75% subset of the data, and their performance was evaluated on the remaining 25%.

RESULTS

We found that models based on baseline clinical parameters or fasting biomarkers could not reliably predict SA. By contrast, an omics model based on magnitude and timing of postprandial biomarkers achieved high performance [receiving operating characteristic (ROC) AUC: 91%; 95% CI: 77, 100). Investigation of key features of this model enabled derivation of a considerably simpler model, solely based on postprandial BP and age, with excellent performance (AUC: 91%; 95% CI: 78, 100).

CONCLUSION

We report a novel model to detect SA based on postprandial BP and age in a population of Asian subjects at low risk of CAD. The use of this model in large-scale CVD prevention programs should be explored. This trial was registered at ClinicalTrials.gov as NCT03531879.

Influence of red blood cell indices on HbA1c performance in detecting dysglycaemia in a Singapore preconception cohort study

Abnormalities of red blood cell (RBC) indices may affect glycated haemoglobin (HbA1c) levels. We assessed the influence of haemoglobin (Hb) and mean corpuscular volume (MCV) on the performance of HbA1c in detecting dysglycaemia among reproductive aged women planning to conceive. Women aged 18-45 years (n = 985) were classified as normal (12 ≤ Hb ≤ 16 g/dL and 80 ≤ MCV ≤ 100 fL) and abnormal (Hb < 12 g/dL and/or MCV < 80 fL). The Area Under the Receiver Operating Characteristic (AUROC) curve was used to determine the performance of HbA1c in detecting dysglycaemic status (prediabetes and diabetes). There were 771 (78.3%) women with normal RBC indices. The AUROCs for the normal and abnormal groups were 0.75 (95% confidence interval 0.69, 0.81) and 0.80 (0.70, 0.90), respectively, and were not statistically different from one another [difference 0.04 (- 0.16, 0.08)]. Further stratification by ethnicity showed no difference between the two groups among Chinese and Indian women. However, Malay women with normal RBC indices displayed lower AUROC compared to those with abnormal RBC indices (0.71 (0.55, 0.87) vs. 0.98 (0.93, 1.00), p = 0.002). The results suggest that the performance of HbA1c in detecting dysglycaemia was not influenced by abnormal RBC indices based on low Hb and/or low MCV. However, there may be ethnic variations among them.

Brown Adipose Tissue, Adiposity, and Metabolic Profile in Preschool Children

CONTEXT

An inverse relationship between brown adipose tissue (BAT) and obesity has previously been reported in older children and adults but is unknown in young children.

OBJECTIVE

We investigated the influence of BAT in thermoneutral condition on adiposity and metabolic profile in Asian preschool children.

DESIGN, SETTING, AND PARTICIPANTS

A total of 198 children aged 4.5 years from a prospective birth cohort study, Growing Up in Singapore Towards Healthy Outcomes (GUSTO) were successfully studied with water-fat magnetic resonance imaging of the supraclavicular and axillary fat depot (FDSA). Regions within FDSA with fat-signal-fraction between 20% and 80% were considered BAT, and percentage BAT (%BAT; 100*BAT volume/ FDSA volume) was calculated.

MAIN OUTCOME MEASURES

Abdominal adipose tissue compartment volumes, ectopic fat in the soleus muscle and liver, fatty liver index, metabolic syndrome scores, and markers of insulin sensitivity.

RESULTS

A 1% unit increase in %BAT was associated with lower body mass index, difference (95% CI), -0.08 (-0.10, -0.06) kg/m2 and smaller abdominal adipose tissue compartment volumes. Ethnicity and sex modified these associations. In addition, each unit increase in %BAT was associated with lower ectopic fat at 4.5 years in the liver, -0.008% (-0.013%, -0.003%); soleus muscle, -0.003% (-0.006%, -0.001%) of water content and lower fatty liver index at 6 years.

CONCLUSIONS

Higher %BAT is associated with a more favorable metabolic profile. BAT may thus play a role in the pathophysiology of obesity and related metabolic disorders. The observed ethnic and sex differences imply that the protective effect of BAT may vary among different groups.

Is Self-Determined Motivation a Useful Agent to Overcome Perceived Exercise Barriers in Patients With Type 2 Diabetes Mellitus?

Background: Devising a program to increase physical activity (PA)/exercise behavior in patients with type 2 diabetes mellitus (T2DM) can meet with limited effectiveness in real-world settings because of the variety of barriers to PA/exercise that individuals need to overcome. An alternative approach is to explore whether targeting motivation as a facilitator may be effective to increase PA/exercise. This study aimed to understand attitudes toward perceived barriers to PA/exercise by examining individual levels of motivation, grounded on self-determination theory, in patients with T2DM. Methods: This study used an integrated approach combining qualitative and quantitative analysis. Sixteen patients with T2DM were grouped (n = 8 for each group) into either a higher self-motivation (HSM) or lower self-motivation (LSM) group via the Relative Autonomy Index. Thematic and deductive analysis were used to identify attitudes based on ten preconceived barrier themes: apathy, dislike, no priority, lack of support, health problems, lack of knowledge, unfavorable environment, tiredness, lack of time, and financial constraints. Quantitative analysis was to assess statistical differences in the volume of PA/exercise across the two groups, and a mixed-methods analysis was employed to highlight unique cases. Results: Patients in the HSM group expressed positive attitudes toward barriers to PA/exercise, while patients in the LSM group expressed a greater degree of hindrance. Although regular PA/exercise is necessary for T2DM management, patients with LSM considered PA/exercise a lesser priority displaying negative attitudes such as apathy and dislike. Conversely, patients with HSM placed greater emphasis on the benefits of PA/exercise regardless of apathy and dislike. Lack of time and health problems were commonly reported in both groups. The volume of PA/exercise corresponded to motivation levels, but there were some unique cases which arose from active commuting habits and severe health problems. Conclusion: These findings provide insights on how attitudes to perceived barriers to PA/exercise differ by levels of motivation. One insight was that examining motivation should be an essential consideration when designing practical strategies to overcome PA/exercise barriers in patients with T2DM. Lack of time and health problems exist regardless of motivation levels. Future research requires a tailored approach to managing barriers to PA/exercise in patients with T2DM.

Aging-induced isoDGR-modified fibronectin activates monocytic and endothelial cells to promote atherosclerosis

BACKGROUND AND AIMS

Aging is the primary risk factor for cardiovascular disease (CVD), but the mechanisms underlying age-linked atherosclerosis remain unclear. We previously observed that long-lived vascular matrix proteins can acquire 'gain-of-function' isoDGR motifs that might play a role in atherosclerotic pathology.

METHODS

IsoDGR-specific mAb were generated and used for ELISA-based measurement of motif levels in plasma samples from patients with coronary artery diseases (CAD) and non-CAD controls. Functional consequences of isoDGR accumulation in age-damaged fibronectin were determined by bioassay for capacity to activate monocytes, macrophages, and endothelial cells (signalling activity, pro-inflammatory cytokine expression, and recruitment/adhesion potential). Mice deficient in the isoDGR repair enzyme PCMT1 were used to assess motif distribution and macrophage localisation in vivo.

RESULTS

IsoDGR-modified fibronectin and fibrinogen levels in patient plasma were significantly enhanced in CAD and further associated with smoking status. Functional assays demonstrated that isoDGR-modified fibronectin activated both monocytes and macrophages via integrin receptor 'outside in' signalling, triggering an ERK:AP-1 cascade and expression of pro-inflammatory cytokines MCP-1 and TNFα to drive additional recruitment of circulating leukocytes. IsoDGR-modified fibronectin also induced endothelial cell expression of integrin β1 to further enhance cellular adhesion and matrix deposition. Analysis of murine aortic tissues confirmed accumulation of isoDGR-modified proteins co-localised with CD68+ macrophages in vivo.

CONCLUSIONS

Age-damaged fibronectin features isoDGR motifs that increase binding to integrins on the surface of monocytes, macrophages, and endothelial cells. Subsequent activation of 'outside-in' signalling elicits a range of potent cytokines and chemokines that drive additional leukocyte recruitment to the developing atherosclerotic matrix.

Plasma Branched-Chain Amino Acids Are Associated With Greater Fasting and Postprandial Insulin Secretion in Non-diabetic Chinese Adults

Background: Plasma branched-chain amino acids (BCAA) are consistently elevated in subjects with obesity and type 2 diabetes (T2DM) and correlate with insulin resistance. The association of BCAA with insulin secretion and clearance rates has not been adequately described. Objective: To evaluate the relationships between fasting and postprandial plasma BCAA, insulin secretion and insulin clearance. Design: Ninety-five non-diabetic Chinese subjects (43 females) underwent a mixed-meal tolerance test; blood biomarkers including BCAAs (leucine, isoleucine, valine) were measured for 6 h. Fasting and postprandial insulin secretion rates (ISR) and insulin clearance were determined by oral minimal modeling of glucose and C-peptide. Results: Fasting and postprandial plasma BCAA correlated strongly with each other (ρ = 0.796, P < 0.001), and both were positively associated with basal ISR (ρ = 0.45/0.36, P < 0.001), total postprandial ISR AUC (ρ = 0.37/0.45, P < 0.001), and negatively with insulin clearance (ρ = -0.29/-0.29, P < 0.01), after adjusting for sex and body mass index. These relationships largely persisted after adjusting further for insulin resistance and postprandial glucose. Compared with subjects in the middle and lowest tertiles for fasting or postprandial plasma BCAA, subjects in the highest tertile had significantly greater postprandial glucose (by 7-10%) and insulin (by 74-98%) concentrations, basal ISRs (by 34-53%), postprandial ISR AUCs (by 41-49%), and lower insulin clearance rates (by 17-22%) (all P < 0.05). Conclusions: Fasting and postprandial plasma BCAA levels are associated with greater fasting and postprandial insulin secretion and reduced insulin clearance in healthy Chinese subjects. These observations potentially highlight an additional layer of involvement of BCAA in the regulation of glucose homeostasis.

Interconversion of Plasma Free Thyroxine Values from Assay Platforms with Different Reference Intervals Using Linear Transformation Methods

Clinicians often encounter thyroid function tests (TFT) comprising serum/plasma free thyroxine (FT4) and thyroid stimulating hormone (TSH) measured using different assay platforms during the course of follow-up evaluations which complicates reliable comparison and interpretation of TFT changes. Although interconversion between concentration units is straightforward, the validity of interconversion of FT4/TSH values from one assay platform to another with different reference intervals remains questionable. This study aims to establish an accurate and reliable methodology of interconverting FT4 by any laboratory to an equivalent FT4 value scaled to a reference range of interest via linear transformation methods. As a proof-of-concept, FT4 was simultaneously assayed by direct analog immunoassay, tandem mass spectrometry and equilibrium dialysis. Both linear and piecewise linear transformations proved relatively accurate for FT4 inter-scale conversion. Linear transformation performs better when FT4 are converted from a more accurate to a less accurate assay platform. The converse is true, whereby piecewise linear transformation is superior to linear transformation when converting values from a less accurate method to a more robust assay platform. Such transformations can potentially apply to other biochemical analytes scale conversions, including TSH. This aids interpretation of TFT trends while monitoring the treatment of patients with thyroid disorders.

Association between Serum Vitamin D Metabolites and Metabolic Function in Healthy Asian Adults

The association between low vitamin D status and the development of type 2 diabetes mellitus is well established; however, intervention trials that increased serum vitamin D (through ultraviolet B exposure or dietary supplementation) provide mixed outcomes. Recent evidence suggests that metabolites directly related to vitamin D receptor activation-1α,25-dihydroxyvitamin D₃ and 24R,25-dihydroxyvitamin D₃-may be better markers of vitamin D repletion status. We tested the hypothesis that a vitamin D metabolite (VDM) index, calculated as the sum of normalized fasting serum concentrations of 1α,25-dihydroxyvitamin D₃ and 24R,25-dihydroxyvitamin D₃, is associated with metabolic function. We measured subcutaneous and visceral adipose tissue volume, intrahepatic triglyceride content, maximum oxygen uptake, insulin sensitivity (4 h hyperinsulinemic-euglycemic clamp), and insulin secretion (3 h meal tolerance test with mathematical modeling) and calculated the VDM index in 65 healthy Asian adults. Subjects with a low VDM index had lower peripheral insulin sensitivity and beta-cell function compared to subjects with a high VDM index (both p < 0.05), matched for age, sex, BMI, and serum 25-hydroxyvitamin D₃. Serum 25-hydroxyvitamin D₃ was not associated with peripheral insulin sensitivity or beta-cell function. Our results suggest that, rather than enhancing vitamin D substrate availability, upregulation of vitamin D action is more likely to lead to improvements in glucose homeostasis.

Lancing Drug Reservoirs into Subcutaneous Fat to Combat Obesity and Associated Metabolic Diseases

Obesity is a serious epidemic health problem that can cause many other diseases including type 2 diabetes and cardiovascular diseases. Current approaches to combat obesity suffer from low effectiveness and adverse side effects. Here, a new self-administrable and minimally invasive transdermal drug delivery strategy for home-based long-term treatment of obesity and other diseases is developed. Specifically, ultrathin, core-shelled, and lance-shaped polymeric drug reservoirs (micro-lances [MLs]) are readily fabricated by a thermal pressing molding method and totally implanted into subcutaneous fat by lancing through the skin. Using a diet-induced obese mouse model, it is shown that the development of obesity and associated metabolic disorders is effectively inhibited by applying therapeutic core-shelled MLs once every 2 weeks. The outstanding therapeutic effects are attributable to highly localized and biphasic drug release, as well as combination therapy based on browning transformation of white fat and enhanced insulin sensitivity.

A Feedforward Loop within the Thyroid-Brown Fat Axis Facilitates Thermoregulation

Thyroid hormones (TH) control brown adipose tissue (BAT) activation and differentiation, but their subsequent homeostatic response following BAT activation remains obscure. This study aimed to investigate the relationship between cold- and capsinoids-induced BAT activation and TH changes between baseline and 2 hours post-intervention. Nineteen healthy subjects underwent ¹⁸F-fluorodeoxyglucose positron-emission tomography (¹⁸F-FDG PET) and whole-body calorimetry (WBC) after 2 hours of cold exposure (~14.5 °C) or capsinoids ingestion (12 mg) in a crossover design. Standardized uptake values (SUV-mean) of the region of interest and energy expenditure (EE) were measured. Plasma free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) were measured before and 2 hours after each intervention. Subjects were divided into groups based on the presence (n = 12) or absence (n = 7) of BAT after cold exposure. 12 of 19 subjects were classified as BAT-positive. Subjects with BAT had higher baseline FT3 concentration, baseline FT3/FT4 ratio compared with subjects without BAT. Controlling for body fat percentage, FT3 concentration at baseline was associated with EE change from baseline after cold exposure (P = 0.037) and capsinoids (P = 0.047). Plasma FT4 level significantly increased associated with reciprocal decline in TSH after acute cold exposure and capsinoids independently of subject and treatment status. Circulating FT3 was higher in BAT-positive subjects and was a stronger predictor of EE changes after cold exposure and capsinoids in healthy humans. BAT activation elevates plasma FT4 acutely and may contribute towards augmentation of thermogenesis via a positive feedback response.

Fibroblast Growth Factor-21, Leptin, and Adiponectin Responses to Acute Cold-Induced Brown Adipose Tissue Activation

BACKGROUND

Adipocyte-derived hormones play a role in insulin sensitivity and energy homeostasis. However, the relationship between circulating fibroblast growth factor 21 (FGF21), adipocytokines and cold-induced supraclavicular brown adipose tissue (sBAT) activation is underexplored.

OBJECTIVE

Our study aimed to investigate the relationships between cold-induced sBAT activity and plasma FGF21 and adipocytokines levels in healthy adults.

DESIGN

Nineteen healthy participants underwent energy expenditure (EE) and supraclavicular infrared thermography (IRT) within a whole-body calorimeter at baseline and at 2 hours post-cold exposure. 18F-fluorodeoxyglucose (18F-FDG) positron-emission tomography/magnetic resonance (PET/MR) imaging scans were performed post-cold exposure. PET sBAT mean standardized uptake value (SUV mean), MR supraclavicular fat fraction (sFF), anterior supraclavicular maximum temperature (Tscv max) and EE change (%) after cold exposure were used to quantify sBAT activity.

MAIN OUTCOME MEASURES

Plasma FGF21, leptin, adiponectin, and tumor necrosis factor alpha (TNFα) at baseline and 2 hours post-cold exposure. Body composition at baseline by dual-energy x-ray absorptiometry (DXA).

RESULTS

Plasma FGF21 and adiponectin levels were significantly reduced after cold exposure in BAT-positive subjects but not in BAT-negative subjects. Leptin concentration was significantly reduced in both BAT-positive and BAT-negative participants after cold exposure. Adiponectin concentration at baseline was positively strongly associated with sBAT PET SUV mean (coefficient, 3269; P = 0.01) and IRT Tscv max (coefficient, 6801; P  = 0.03), and inversely correlated with MR sFF (coefficient, -404; P  = 0.02) after cold exposure in BAT-positive subjects but not in BAT-negative subjects.

CONCLUSION

Higher adiponectin concentrations at baseline indicate a greater cold-induced sBAT activity, which may be a novel predictor for sBAT activity in healthy BAT-positive adults.

HIGHLIGHTS

A higher adiponectin concentration at baseline was associated with higher cold-induced supraclavicular BAT PET SUV mean and IRT Tscv max, and lower MR supraclavicular FF. Adiponectin levels maybe a novel predictor for cold-induced sBAT activity.

Dynamic contrast-enhanced MRI of brown and beige adipose tissues

PURPOSE

The vascular blood flow in brown adipose tissue (BAT) is important for handling triglyceride clearance, increased blood flow and oxygenation. We used dynamic contrast-enhanced (DCE)-MRI and fat fraction (FF) imaging for investigating vascular perfusion kinetics in brown and beige adipose tissues with cold exposure or treatment with β3-adrenergic agonist.

METHODS

FF imaging and DCE-MRI using gadolinium-diethylenetriaminepentaacetic acid were performed in interscapular BAT (iBAT) and beige tissues using male Wister rats (n = 38). Imaging was performed at thermoneutral condition and with either cold exposure, treatment with pharmacological agent CL-316,243, or saline. DCE-MRI and FF data were co-registered to enhance the understanding of metabolic activity.

RESULTS

Uptake of contrast agent in activated iBAT and beige tissues were significantly (P < .05) higher than nonactivated iBAT. The K^trans and k_ep increased significantly in iBAT and beige tissues after treatment with either cold exposure or β3-adrenergic agonist. The FF decreased in activated iBAT and beige tissues. The K^trans and FF from iBAT and beige tissues were inversely correlated (r = 0.97; r = 0.94). Significant increase in vascular endothelial growth factor expression and K^trans in activated iBAT and beige tissues were in agreement with the increased vasculature and vascular perfusion kinetics. The iBAT and beige tissues were validated by measuring molecular markers.

CONCLUSION

Increased K^trans and decreased FF in iBAT and beige tissues were in agreement with the vascular perfusion kinetics facilitating the clearance of free fatty acids. The methodology can be extended for the screening of browning agents.

Differential Effects of Monounsaturated and Polyunsaturated Fats on Satiety and Gut Hormone Responses in Healthy Subjects

The difference between fat saturation on postprandial hormone responses and acute appetite control is not well understood. The aim of this study was to compare the postprandial ghrelin, gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP1) response and subjective appetite responses after isoenergetic high-fat meals rich in either monounsaturated (MUFAs) or polyunsaturated fatty acids (PUFAs) in healthy Chinese males. A randomized, controlled, single-blinded crossover study was conducted in 13 healthy Chinese men. Two high-fat meals (64% of energy) rich in MUFAs or PUFAs were tested. Total ghrelin, GIP and active GLP1 and visual analog scale (VAS) were measured over 4 h. Ghrelin was reduced greater after MUFA compared to PUFA at the beginning of the meal (at 30 and 60 min) and was significantly negatively correlated with subjective VAS for preoccupation for both MUFA and PUFA meals. No significant difference for ghrelin 240 min incremental area under the curve (iAUCs) were found. MUFA induced higher GIP response than PUFA. GIP was associated with all the VAS measurements except preoccupation for MUFA meal. No difference was found for GLP1 between two meals, nor was GLP1 associated with VAS. In conclusion, the results demonstrate that ghrelin, GIP and VAS respond differently to MUFA and PUFA meals. Ghrelin and GIP, but not GLP1, were associated with acute appetite control, especially after MUFA meal.

Brown Adipose Tissue: Multimodality Evaluation by PET, MRI, Infrared Thermography, and Whole-Body Calorimetry (TACTICAL-II)

OBJECTIVE

This study aimed to compare the associations of positron emission tomography (PET), magnetic resonance (MR), and infrared thermography (IRT) imaging modalities with energy expenditure (EE) after brown adipose tissue (BAT) activation using capsinoid ingestion and cold exposure.

METHODS

Twenty participants underwent PET-MR, IRT imaging, and whole-body calorimetry after capsinoid ingestion and cold exposure. Standardized uptake values (SUV) and the fat fraction (FF) of the supraclavicular brown adipose tissue regions were estimated. The anterior supraclavicular temperature (Tscv) from IRT at baseline and postintervention was measured. Two-hour post-capsinoid ingestion EE and post-cold exposure EE served as a reference to correlate fluorodeoxyglucose uptake, FF, and Tscv for BAT assessment. IRT images were geometrically transformed to overlay on PET-MR for visualization of the hottest regions.

RESULTS

The supraclavicular hot spot identified on IRT closely corresponded to the area of maximal fluorodeoxyglucose uptake on PET images. Controlling for body weight, post-cold exposure Tscv was a significant variable associated with EE (P = 0.025). The SUV was significantly inversely correlated with FF (P = 0.012) and significantly correlated with peak of Tscv during cold exposure in BAT-positive participants (P = 0.022).

CONCLUSIONS

Tscv correlated positively with EE and was also significantly correlated with SUV after cold exposure. Both IRT and MR FF are promising methods to study BAT activity noninvasively.

Associations of physical activity levels and screen time with oral glucose tolerance test profiles in Singaporean women of reproductive age actively trying to conceive: the S-PRESTO study

AIM

To examine the associations of physical activity and screen time, a proxy for sedentary behaviour, with fasting and post-load glucose levels in Singaporean women enrolled in a multi-ethnic Asian preconception study.

METHODS

Moderate and vigorous physical activity and screen time (television and other electronic devices) were self-reported by women enrolled in the S-PRESTO cohort. Fasting, 30-min and 120-min glucose levels before and during a 75-g oral glucose tolerance test were measured. Associations of physical activity and screen time with glucose levels were analysed using multivariable linear marginal regression.

RESULTS

A total of 946 women aged 31.4±3.7 years were examined, of whom 72% were of Chinese, 15.5% were of Malay, 9.3% were of Indian and 3.2% were of mixed ethnicity. A total of 32% of women reported being active, 36% watched television ≥2 h/day and 26% used electronic devices ≥3 h/day. In adjusted models, vigorous, but not moderate, physical activity was associated with lower overall glucose levels, and was associated more strongly with post-challenge than fasting glucose levels. Compared to women not engaging in vigorous physical activity, those engaging in physical activity ≥75 min/week had lower mean fasting [-0.14 (95% CI -0.28, -0.01) mmol/l], 30-min [0.35 (95% CI -0.68, -0.02) mmol/l] and 120-min [-0.53 (95% CI -0.16, -0.90) mmol/l] glucose levels (overall P value=0.05). We found no associations of screen time with glucose levels.

CONCLUSIONS

Independently of the time spent in non-vigorous physical activity and using screens, engaging in vigorous physical activity may be a modifiable factor to improve glucose regulation in women of Asian ethnicity who are attempting to conceive.

Can the Sequence of Food Presentation Influence Postprandial Glycaemia? (P10-072-19)

Objectives

The study was to investigate how a rice-based meal composed of rice, vegetable (green leaf) and meat (breast of chicken) when presented in different order of sequence, impacts on postprandial glycaemia.

Methods

In a randomized controlled crossover trial, sixteen healthy Chinese adults participated in this study (13 males and 3 females). Subjects consumed in random order 5 experimental meals. The 5 test meal were: (1) vegetables first followed by meat and rice (V-MR), (2) meat first followed by vegetables and rice (M-VR), (3) vegetables first, meat second followed by rice (V-M-R), (4) vegetables, meat and rice together (VMR), (5) rice followed by vegetables and meat (R-VM). Vegetable consumed first followed by meat and rice (V-MR), finally vegetable consumed first, followed by meat and followed by rice (V-M-R).

Results

In comparison to rice consumed first followed by vegetable and meat (R-VM), the overall postprandial glucose response was significantly lower after the consumption of vegetable first, followed by meat and rice (V-MR) or meat first, followed by vegetable and rice (M-VR) or vegetable followed by meat and followed by rice (V-M-R) or vegetable, meat and rice consumed together (VMR). The insulin iAUC (0–60) was significantly lower after V-M-R than M-VR, VMR and R-VM. V-M-R food sequence intake stimulated higher GLP-1 release than other meal sequence. However, GIP response was lower after V-MR and V-M-R than M-VR and R-MR food sequence.

Conclusions

Food sequence can considerably influence a meals response to glycaemic, insulinaemic and incretin. V-M-R food sequence intake lowered the glycaemic response significantly with an increased stimulation of GLP1. The order of food presentation has a great potential to alter the glycaemic response of rice-based diets. Our results provide a simple but effective way to reduce postprandial glucose and may help prevent the transition from pre-diabetics to diabetics

Funding Sources

Singapore Institute for Clinical Sciences, A*STAR, Singapore.

Supporting Tables, Images and/or Graphs

Postprandial glucose, insulin and incretin responses differ by test meal macronutrient ingestion sequence (PATTERN study)

BACKGROUND

Previous studies have shown that the sequential order of consuming different food components significantly impacts postprandial glucose and insulin excursions in prediabetes and type 2 diabetes, but the causative mechanisms in healthy humans remain ill-defined.

OBJECTIVE

Using a typical Asian meal comprising vegetables, protein (chicken breast), and carbohydrate (white rice), the aim of this study was to examine the effect of food intake sequence on postprandial glucose, insulin and incretin secretions in healthy adults.

DESIGN

Sixteen healthy Chinese adults participated in a randomized, controlled, crossover meal trial. Subjects consumed in random order 5 experimental isocaloric meals that differed in the food intake sequence of vegetables, protein and carbohydrate. Glucose, insulin, incretins and satiety markers were measured over 3 h.

RESULTS

There were significant food intake sequence × time interaction effects on plasma glucose, insulin, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) concentrations (P < 0.001). In comparison with rice consumed first followed by vegetable and meat (R-VM), the overall postprandial glucose response was significantly attenuated after the food intake sequence of vegetable first, followed by meat and rice (V-MR) or meat first, followed by vegetable and rice (M-VR) or vegetable first followed by meat and rice (V-M-R) or vegetable, meat and rice consumed together (VMR). The insulin iAUC (0-60) was significant lower after V-M-R than M-VR, VMR and R-VM. V-M-R food intake sequence stimulated higher GLP-1 release than other meal sequences. However, GIP response was lower after V-MR and V-M-R than M-VR and R-MR food intake sequences.

CONCLUSIONS

Food macronutrient intake sequence can considerably influence its glycemic, insulinemic and incretin responses. V-M-R food intake sequence attenuates the glycemic response to a greater degree with accentuated GLP-1 stimulation without any increased demand for insulin. The sequence of food intake has great potential as a novel and simple behavioral strategy to modulate glycemic response in healthy adults. The trial was registered at clinicaltrials.gov as NCT03533738.

Design of an online-tuned model based compound controller for a fully automated artificial pancreas

This paper deals with the development of a control algorithm that can predict optimal insulin doses without patients' intervention in fully automated artificial pancreas system. An online-tuned model based compound controller comprising an online-tuned internal model control (IMC) algorithm and an enhanced IMC (eIMC) algorithm along with a meal detection module is proposed. Volterra models, used to develop IMC and eIMC algorithms, are developed online using recursive least squares (RLS) filter. The time domain kernels, computed online using RLS filter, are converted into frequency domain to obtain Volterra transfer function (VTF). VTFs are used to develop both IMC and eIMC algorithms. The compound controller is designed in such a way that eIMC predicts insulin doses when the glucose rate increase detector of meal detection module is positive, otherwise conventional IMC takes the control action. Experimental results show that the compound controller performs robustly in the presence of higher and irregular amounts of meal disturbances at random times, very high actuator and sensor noises and also with the variation in insulin sensitivity. The combination of compound control strategy and meal detection module compensates the shortcomings of both slow subcutaneous insulin action that causes postprandial hyperglycemia, and delayed peak of action that causes hypoglycaemia. Graphical Abstract A fully-automated artificial pancreas system containing glucose sensor, insulin pump and control algorithm. Block diagram showing the control algorithm i.e., online-tuned compound IMC comprising enhanced IMC, conventional IMC and meal detection module, developed in the present work.

Association Between Early Life Weight Gain and Abdominal Fat Partitioning at 4.5 Years is Sex, Ethnicity, and Age Dependent

OBJECTIVE

The aim of this study was to investigate the independent associations between age-specific annual weight gain from birth to age 4 years and fat deposition in metabolically distinct compartments at age 4.5 years in a South Asian longitudinal birth cohort.

METHODS

Volumetric abdominal magnetic resonance imaging with comprehensive segmentation of deep and superficial subcutaneous adipose tissue (SAT) and visceral adipose tissues (VAT) was performed in 316 children (150 boys and 166 girls in three ethnic groups; 158 Chinese, 94 Malay, and 64 Indian) aged 4.5 years. Associations between fat volumes and annual relative weight gain conditional on past growth were assessed overall and stratified by sex and ethnicity.

RESULTS

Conditional relative weight gain had stronger associations with greater SAT and VAT at age 4.5 years in girls than boys and in Indians compared with Malay and Chinese. Overall, the magnitude of association was the largest during 2 to 3 years for SAT and 1 to 2 years for VAT. Despite similar body weight, Indian children and girls had the highest deep and superficial SAT volumes at age 4.5 years (all interactions P < 0.05). No significant sex or ethnic differences were observed in VAT. With increasing BMI, Indian children had the highest tendency to accumulate VAT, and girls accumulated more fat than boys in all depots (all interactions P < 0.001).

CONCLUSIONS

Indian ethnicity and female sex predisposed children to accumulate more fat in the VAT depot with increasing conditional relative weight gain in the second year of life. Thus, 1 to 2 years of age may be a critical window for interventions to reduce visceral fat accumulation.

Ethnicity-Specific Skeletal Muscle Transcriptional Signatures and Their Relevance to Insulin Resistance in Singapore

CONTEXT

Insulin resistance (IR) and obesity differ among ethnic groups in Singapore, with the Malays more obese yet less IR than Asian-Indians. However, the molecular basis underlying these differences is not clear.

OBJECTIVE

As the skeletal muscle (SM) is metabolically relevant to IR, we investigated molecular pathways in SM that are associated with ethnic differences in IR, obesity, and related traits.

DESIGN, SETTING, AND MAIN OUTCOME MEASURES

We integrated transcriptomic, genomic, and phenotypic analyses in 156 healthy subjects representing three major ethnicities in the Singapore Adult Metabolism Study.

PATIENTS

This study contains Chinese (n = 63), Malay (n = 51), and Asian-Indian (n = 42) men, aged 21 to 40 years, without systemic diseases.

RESULTS

We found remarkable diversity in the SM transcriptome among the three ethnicities, with >8000 differentially expressed genes (40% of all genes expressed in SM). Comparison with blood transcriptome from a separate Singaporean cohort showed that >95% of SM expression differences among ethnicities were unique to SM. We identified a network of 46 genes that were specifically downregulated in Malays, suggesting dysregulation of components of cellular respiration in SM of Malay individuals. We also report 28 differentially expressed gene clusters, four of which were also enriched for genes that were found in genome-wide association studies of metabolic traits and disease and correlated with variation in IR, obesity, and related traits.

CONCLUSION

We identified extensive gene-expression changes in SM among the three Singaporean ethnicities and report specific genes and molecular pathways that might underpin and explain the differences in IR among these ethnic groups.

Adipocyte Long-Noncoding RNA Transcriptome Analysis of Obese Mice Identified Lnc-Leptin, Which Regulates Leptin

Obesity induces profound transcriptome changes in adipocytes, and recent evidence suggests that long-noncoding RNAs (lncRNAs) play key roles in this process. We performed a comprehensive transcriptome study by RNA sequencing in adipocytes isolated from interscapular brown, inguinal, and epididymal white adipose tissue in diet-induced obese mice. The analysis revealed a set of obesity-dysregulated lncRNAs, many of which exhibit dynamic changes in the fed versus fasted state, potentially serving as novel molecular markers of adipose energy status. Among the most prominent lncRNAs is Lnc-leptin, which is transcribed from an enhancer region upstream of leptin (Lep). Expression of Lnc-leptin is sensitive to insulin and closely correlates to Lep expression across diverse pathophysiological conditions. Functionally, induction of Lnc-leptin is essential for adipogenesis, and its presence is required for the maintenance of Lep expression in vitro and in vivo. Direct interaction was detected between DNA loci of Lnc-leptin and Lep in mature adipocytes, which diminished upon Lnc-leptin knockdown. Our study establishes Lnc-leptin as a new regulator of Lep.

De novo reconstruction of human adipose transcriptome reveals conserved lncRNAs as regulators of brown adipogenesis

Obesity has emerged as an alarming health crisis due to its association with metabolic risk factors such as diabetes, dyslipidemia, and hypertension. Recent work has demonstrated the multifaceted roles of lncRNAs in regulating mouse adipose development, but their implication in human adipocytes remains largely unknown. Here we present a catalog of 3149 adipose active lncRNAs, of which 909 are specifically detected in brown adipose tissue (BAT) by performing deep RNA-seq on adult subcutaneous, omental white adipose tissue and fetal BATs. A total of 169 conserved human lncRNAs show positive correlation with their nearby mRNAs, and knockdown assay supports a role of lncRNAs in regulating their nearby mRNAs. The knockdown of one of those, lnc-dPrdm16, impairs brown adipocyte differentiation in vitro and a significant reduction of BAT-selective markers in in vivo. Together, our work provides a comprehensive human adipose catalog built from diverse fat depots and establishes a roadmap to facilitate the discovery of functional lncRNAs in adipocyte development.

Long non-coding RNAs are known to regulate mouse white adipose tissue development and brown adipose tissue program expression. Here, the authors construct a roadmap for human long non-coding RNAs expressed in fetal brown adipose tissue, adult omental and subcutaneous white adipose tissues.

Capsinoids activate brown adipose tissue (BAT) with increased energy expenditure associated with subthreshold 18-fluorine fluorodeoxyglucose uptake in BAT-positive humans confirmed by positron emission tomography scan

Background

Capsinoids are reported to increase energy expenditure (EE) via brown adipose tissue (BAT) stimulation. However, imaging of BAT activation by capsinoids remains limited. Because BAT activation is a potential therapeutic strategy for obesity and related metabolic disorders, we sought to prove that capsinoid-induced BAT activation can be visualized by 18-fluorine fluorodeoxyglucose (18F-FDG) positron emission tomography (PET).

Objective

We compared capsinoids and cold exposure on BAT activation and whole-body EE.

Design

Twenty healthy participants (8 men, 12 women) with a mean age of 26 y (range: 21-35 y) and a body mass index (kg/m2) of 21.7 (range: 18.5-26.0) underwent 18F-FDG PET and whole-body calorimetry after ingestion of 12 mg capsinoids or ≤2 h of cold exposure (∼14.5°C) in a crossover design. Mean standardized uptake values (SUVs) of the region of interest and BAT volumes were calculated. Blood metabolites were measured before and 2 h after each treatment.

Results

All of the participants showed negligible 18F-FDG uptake post-capsinoid ingestion. Upon cold exposure, 12 participants showed avid 18F-FDG uptake into supraclavicular and lateral neck adipose tissues (BAT-positive group), whereas the remaining 8 participants (BAT-negative group) showed undetectable uptake. Capsinoids and cold exposure increased EE, although cold induced a 2-fold increase in whole-body EE and higher fat oxidation, insulin sensitivity, and HDL cholesterol compared with capsinoids.

Conclusions

Capsinoids only increased EE in BAT-positive participants, which suggests that BAT mediates EE evoked by capsinoids. This implies that capsinoids stimulate BAT to a lesser degree than cold exposure as evidenced by 18F-FDG uptake below the presently accepted SUV thresholds defining BAT activation. This trial was registered at www.clinicaltrials.gov as NCT02964442.

Polyphenol-rich curry made with mixed spices and vegetables benefits glucose homeostasis in Chinese males (Polyspice Study): a dose-response randomized controlled crossover trial

PURPOSE

To investigate acute effects of two doses of a polyphenol-rich curry made with seven different spices and four base vegetables, eaten with white rice, on 24 h glucose response, postprandial insulinemia, triglyceridemia and 24 h urinary total polyphenol excretion (TPE).

METHODS

Randomized, controlled, dose-response crossover trial in healthy, Chinese men [n = 20, mean ± standard deviation (SD) age 23.7 ± 2.30 years, BMI 23.0 ± 2.31 kg/m²] who consumed test meals matched for calories, macronutrients and total vegetables content, consisting either Dose 0 Control (D0C) or Dose 1 Curry (D1C) or Dose 2 Curry (D2C) meal. 24 h glucose concentration was measured using continuous glucose monitoring (CGM), together with postprandial plasma insulin and triglyceride for up to 7 h. Total polyphenol content (TPC) of test meals and urinary TPE were measured using the Folin-Ciocalteu assay.

RESULTS

TPC for D0C, D1C and D2C were 130 ± 18, 556 ± 19.7 and 1113 ± 211.6 mg gallic acid equivalent (GAE) per portion served, respectively (p < 0.0001). Compared with D0C meal, we found significant linear dose-response reductions in the 3-h postprandial incremental AUC (iAUC) for CGM glucose of 19% and 32% during D1C and D2C meals respectively (p < 0.05) and non-significant linear dose response reductions in iAUC of insulin (p = 0.089). Notably, we found significant dose-dependent increases in postprandial triglyceride with increasing curry doses (p < 0.01). Significant increases in TPE with increasing curry doses were also observed (p < 0.01).

CONCLUSION

Polyphenol-rich curry intake can improve postprandial glucose homeostasis. The longer term effects remain to be established.

RNA Binding Protein Ybx2 Regulates RNA Stability During Cold-Induced Brown Fat Activation

Recent years have seen an upsurge of interest in brown adipose tissue (BAT) to combat the epidemic of obesity and diabetes. How its development and activation are regulated at the posttranscriptional level, however, has yet to be fully understood. RNA binding proteins (RBPs) lie in the center of posttranscriptional regulation. To systemically study the role of RBPs in BAT, we profiled >400 RBPs in different adipose depots and identified Y-box binding protein 2 (Ybx2) as a novel regulator in BAT activation. Knockdown of Ybx2 blocks brown adipogenesis, whereas its overexpression promotes BAT marker expression in brown and white adipocytes. Ybx2-knockout mice could form BAT but failed to express a full thermogenic program. Integrative analysis of RNA sequencing and RNA-immunoprecipitation study revealed a set of Ybx2's mRNA targets, including Pgc1α, that were destabilized by Ybx2 depletion during cold-induced activation. Thus, Ybx2 is a novel regulator that controls BAT activation by regulating mRNA stability.

Angiotensin type 2 receptor activation promotes browning of white adipose tissue and brown adipogenesis

Brown adipose tissue dissipates energy in the form of heat. Recent studies have shown that adult humans possess both classical brown and beige adipocytes (brown-like adipocytes in white adipose tissue, WAT), and stimulating brown and beige adipocyte formation can be a new avenue to treat obesity. Angiotensin II (AngII) is a peptide hormone that plays important roles in energy metabolism via its angiotensin type 1 or type 2 receptors (AT1R and AT2R). Adipose tissue is a major source of AngII and expresses both types of its receptors, implying the autocrine and paracrine role of AngII in regulating adipose functions and self-remodeling. Here, based on the in vitro studies on primary cultures of mouse white adipocytes, we report that, AT2R activation, either by AngII or AT2R agonist (C21), induces white adipocyte browning, by increasing PPARγ expression, at least in part, via ERK1/2, PI3kinase/Akt and AMPK signaling pathways. It is also found that AngII–AT2R enhances brown adipogenesis. In the in vivo studies on mice, administration of AT1R antagonist (ZD7155) or AT2R agonist (C21) leads to the increase of WAT browning, body temperature and serum adiponectin, as well as the decrease of WAT mass and the serum levels of TNFα, triglycerides and free fatty acids. In addition, AT2R-induced browning effect is also observed in human white adipocytes, as evidenced by the increased UCP1 expression and oxygen consumption. Finally, we provide evidence that AT2R plays important roles in hormone T3-induced white adipose browning. This study, for the first time, reveals the browning and brown adipogenic effects of AT2R and suggests a potential therapeutic target to combat obesity and related metabolic disorders.

Changes in Hepatic TRβ Protein Expression, Lipogenic Gene Expression, and Long-Chain Acylcarnitine Levels During Chronic Hyperthyroidism and Triiodothyronine Withdrawal in a Mouse Model

BACKGROUND

Thyroid hormone (TH) has important roles in regulating hepatic metabolism. It was previously reported that most hepatic genes activated by a single triiodothyronine (T3) injection became desensitized after multiple injections, and that approximately 10% of target genes did not return to basal expression levels after T3 withdrawal, despite normalization of serum TH and thyrotropin (TSH) levels. To determine the possible mechanism(s) for desensitization and incomplete recovery of hepatic target gene transcription and their effects on metabolism, mRNA and/or protein expression levels of key regulators of TH action were measured, as well as metabolomic changes after chronic T3 treatment and withdrawal.

METHODS

Adult male mice were treated with daily injections of T3 (20 μg/100 g body weight) for 14 days followed by the cessation of T3 for 10 days. Livers were harvested at 6 hours, 24 hours, and 14 days after the first T3 injection, and at 10 days after withdrawal, and then analyzed by quantitative reverse transcription polymerase chain reaction, Western blotting, and metabolomics.

RESULTS

Although TH receptor (TRα and TRβ) mRNAs decreased slightly after chronic T3 treatment, only TRβ protein decreased before returning to basal expression level after withdrawal. The expression of other regulators of TH action was unchanged. TRβ protein expression was also decreased in adult male monocarboxylate transporter-8 (Mct8)-knockout mice, an in vivo model of chronic intrahepatic hyperthyroidism. Previously, increased hepatic long-chain acylcarnitine levels were found after acute TH treatment. However, in this study, long-chain acylcarnitine levels were unchanged after chronic T3, and paradoxically increased after T3 withdrawal. Pathway analyses of the previous microarray results showed upregulation of lipogenic genes after acute T3 treatment and withdrawal. Phosphorylation of acetyl-CoA carboxylase also decreased after T3 withdrawal.

CONCLUSIONS

Decreased hepatic TRβ protein expression occurred after chronic T3 exposure in adult male wild-type and Mct8-knockout mice. Gene array pathway and metabolomics analyses showed abnormalities in hepatic lipogenic gene expression and acylcarnitine levels, respectively, after withdrawal, despite normalization of serum TSH and TH levels. These findings may help explain the variable clinical presentations of some patients during hyperthyroidism and recovery, since TRβ protein, target gene expression, and metabolic adaptive changes can occur in individual tissues without necessarily being reflected by circulating TH and TSH concentrations.

High Resolution Free Triiodothyronine-Thyrotropin (FT3-TSH) Responses to a Single Oral Dose of Liothyronine in Humans: Evidence of Distinct Inter-Individual Differences Unraveled Using an Electrical Network Model

The effects of a single oral dose of liothyronine (L-T3) on thyroid stimulating hormone (TSH) and other related thyroid system parameters are partly understood despite therapeutic use of this hormone over many decades. We characterize individualized responses of the hypothalamus-pituitary-thyroid (HPT) axis and its related temporal hormonal profile using an electrical network model. Based on thyroid hormone responses from blood samples using a single 50 μg oral dose of liothyronine in healthy persons with a normal operating euthyroid feedback HPT system, we derived an equivalent electrical circuit model for the system's responses. The mathematical model was tested with a circuit simulator and validated with individualized clinical data. This signal processing technique makes the evaluation of bioequivalence and bioavailability of various preparations of liothyronine at an individualized level a feasible endeavor for clinical application.

Characterization of the Asian Phenotype - An Emerging Paradigm with Clinicopathological and Human Research Implications

Background: Modern medicine recognizes that salient, inherent variations between Caucasians and Asians exist. Radical changes are occurring in the health scene with increasing emphasis centered on the recognition of inter-individual variations unique to Asians that impact on medical management and outcomes. Aim: This review analyzes distinct features or outcomes in terms of epidemiology, disease thresholds, diagnostic cutoffs and treatment responses of Asian people compared with non-Asians. Methods: This review is based on a literature search via PubMed and MEDLINE for relevant articles related to the Asian phenotype and its impact on health and disease. Results: An 'Asian phenotype' could be characterized across the spectrum of biomedical disciplines and underscores the major challenges clinicians must face in their daily management of a cosmopolitan population and their extrapolation of research outcomes. Conclusion: Interventions for various ailments that have traditionally ignored population differences have now entered the age of personalized, stratified or precision medicine requiring an individualized approach being adopted as a new standard of care. Factoring in Asian phenotypes is essential for the medical research community and the development of improved clinical practice guidelines across a continuum of disciplines that will ultimately translate to better human health round the world.

Desensitization and Incomplete Recovery of Hepatic Target Genes After Chronic Thyroid Hormone Treatment and Withdrawal in Male Adult Mice

Clinical symptoms may vary and not necessarily reflect serum thyroid hormone (TH) levels during acute and chronic hyperthyroidism as well as recovery from hyperthyroidism. We thus examined changes in hepatic gene expression and serum TH/TSH levels in adult male mice treated either with a single T3 (20 μg per 100 g body weight) injection (acute T3) or daily injections for 14 days (chronic T3) followed by 10 days of withdrawal. Gene expression arrays from livers harvested at these time points showed that among positively-regulated target genes, 320 were stimulated acutely and 429 chronically by T3. Surprisingly, only 69 of 680 genes (10.1%) were induced during both periods, suggesting desensitization of the majority of acutely stimulated target genes. About 90% of positively regulated target genes returned to baseline expression levels after 10 days of withdrawal; however, 67 of 680 (9.9%) did not return to baseline despite normalization of serum TH/TSH levels. Similar findings also were observed for negatively regulated target genes. Chromatin immunoprecipitation analysis of representative positively regulated target genes suggested that acetylation of H3K9/K14 was associated with acute stimulation, whereas trimethylation of H3K4 was associated with chronic stimulation. In an in vivo model of chronic intrahepatic hyperthyroidism since birth, adult male monocarboxylate transporter-8 knockout mice also demonstrated desensitization of most acutely stimulated target genes that were examined. In summary, we have identified transcriptional desensitization and incomplete recovery of gene expression during chronic hyperthyroidism and recovery. Our findings may be a potential reason for discordance between clinical symptoms and serum TH levels observed in these conditions.

Postprandial changes in cardiometabolic disease risk in young Chinese men following isocaloric high or low protein diets, stratified by either high or low meal frequency - a randomized controlled crossover trial

Background

Cardio-Metabolic Disease (CMD) is the leading cause of death globally and particularly in Asia. Postprandial elevation of glycaemia, insulinaemia, triglyceridaemia are associated with an increased risk of CMD. While studies have shown that higher protein intake or increased meal frequency may benefit postprandial metabolism, their combined effect has rarely been investigated using composite mixed meals. We therefore examined the combined effects of increasing meal frequency (2-large vs 6-smaller meals), with high or low-protein (40 % vs 10 % energy from protein respectively) isocaloric mixed meals on a range of postprandial CMD risk markers.

Methods

In a randomized crossover study, 10 healthy Chinese males (Age: 29 ± 7 years; BMI: 21.9 ± 1.7 kg/m²) underwent 4 dietary treatments: CON-2 (2 large Low-Protein meals), CON-6 (6 Small Low-Protein meals), PRO-2 (2 Large High-Protein meals) and PRO-6 (6 Small High-Protein meals). Subjects wore a continuous glucose monitor (CGM) and venous blood samples were obtained at baseline and at regular intervals for 8.5 h to monitor postprandial changes in glucose, insulin, triglycerides and high sensitivity C-reactive protein (hsCRP). Blood pressure was measured at regular intervals pre- and post- meal consumption. Urine was collected to measure excretion of creatinine and F₂-isoprostanes and its metabolites over the 8.5 h postprandial period.

Results

The high-protein meals, irrespective of meal frequency were beneficial for glycaemic health since glucose incremental area under the curve (iAUC) for PRO-2 (185 ± 166 mmol.min.L⁻¹) and PRO-6 (214 ± 188 mmol.min.L⁻¹) were 66 and 60 % lower respectively (both p < 0.05), compared with CON-2 (536 ± 290 mmol.min.L⁻¹). The iAUC for insulin was the lowest for PRO-6 (13.7 ± 7.1 U.min.L⁻¹) as compared with CON-2 (28.4 ± 15.6 U.min.L⁻1), p < 0.001. There were no significant differences in postprandial responses in other measurements between the dietary treatments.

Conclusions

The consumption of composite meals with higher protein content, irrespective of meal frequency appears to be beneficial for postprandial glycemic and insulinemic responses in young, healthy Chinese males. Implications of this study may be useful in the Asian context where the consumption of high glycemic index, carbohydrate meals is prevalent.

Trial registration

NCT02529228.

Psychometric analysis of an eating behaviour questionnaire for an overweight and obese Chinese population in Singapore

OBJECTIVES

Previous studies reveal that the Three-Factor Eating Questionnaire (TFEQ), which assesses eating behaviour, performs differently across population groups and cultures. We aimed to identify the factor structure that is most appropriate to capture eating behaviour in an overweight and obese Chinese population in Singapore.

METHODS

TFEQ-51 was administered to 444 Chinese subjects pooled from four separate studies and scored according to various alternative versions of the TFEQ. Confirmatory factor analyses and goodness of fit indices were used to determine the most appropriate factor structure. Known-group validity analyses were conducted.

RESULTS

Niemeier's Disinhibition Factors and the TFEQ-R18 factor structures were found to be the most applicable in our population based on goodness of fit indices, with a x(2)/df ratio of <3, RMSEA of ≤ 0.6 and a CFI value of >0.9 for both. Only two of three factors (Emotional Eating and Uncontrolled Eating) of the TFEQ-R18 showed good internal consistency, while none of Niemeier's Disinhibition Factors showed good internal consistency. Known-group validity showed that Emotional Eating and Internal Disinhibition were significantly associated with higher BMI.

CONCLUSION

We found that the TFEQ-R18 factor structure is the most appropriate and practical for use in measuring eating behaviour in an overweight and obese Chinese population in Singapore.

A Review of the Phenomenon of Hysteresis in the Hypothalamus-Pituitary-Thyroid Axis

The existence of a phase of prolonged suppression of TSH despite normalization of serum thyroid hormones over a variable period of time during the recovery of thyrotoxicosis has been documented in literature. Conversely, a temporary elevation of TSH despite attainment of euthyroid levels of serum thyroid hormones following extreme hypothyroidism has also been observed. This rate-independent lag time in TSH recovery is an evidence of a "persistent memory" of the history of dysthyroid states the hypothalamus-pituitary-thyroid (HPT) axis has encountered after the thyroid hormone perturbations have faded out, a phenomenon termed "hysteresis." Notwithstanding its perplexing nature, hysteresis impacts upon the interpretation of thyroid function tests with sufficient regularity that clinicians risk misdiagnosing and implementing erroneous treatment out of ignorance of this aspect of thyrotropic biology. Mathematical modeling of this phenomenon is complicated but may allow the euthyroid set point to be predicted from thyroid function data exhibiting strong hysteresis effects. Such model predictions are potentially useful for clinical management. Although the molecular mechanisms mediating hysteresis remain elusive, epigenetics, such as histone modifications, are probably involved. However, attempts to reverse the process to hasten the resolution of the hysteretic process may not necessarily translate into improved physiology or optimal health benefits. This is not unexpected from teleological considerations, since hysteresis probably represents an adaptive endocrinological response with survival advantages evolutionarily conserved among vertebrates with a HPT system.

Ethnic Differences in the Role of Adipocytokines Linking Abdominal Adiposity and Insulin Sensitivity Among Asians

CONTEXT

Among Asian ethnic groups, Chinese or Malays are more insulin sensitive than South Asians, in particular in lean individuals. We have further reported that body fat partitioning did not explain this ethnic difference in insulin sensitivity.

OBJECTIVE

We examined whether adipocytokines might explain the ethnic differences in the relationship between obesity and insulin resistance among the three major ethnic groups in Singapore.

DESIGN AND PARTICIPANTS

This was a cross-sectional study of 101 Chinese, 82 Malays, and 81 South Asian men. Insulin sensitivity index (ISI) was measured using hyperinsulinemic euglycemic clamp. Visceral (VAT) and subcutaneous adipose tissue (SAT) volumes were quantified using magnetic resonance imaging.

MAIN OUTCOME MEASURES

Plasma total and high-molecular-weight adiponectin, leptin, visfatin, apelin, IL-6, fibroblast growth factor 21 (FGF21), retinol binding protein-4 (RBP 4), and resistin were measured using enzyme-linked immunoassays.

RESULTS

Principle component (PC) analysis on the adipocytokines identified three PCs, which explained 49.5% of the total variance. Adiponectin loaded negatively, and leptin and FGF21 loaded positively onto PC1. Visfatin, resistin, and apelin all loaded positively onto PC2. IL-6 loaded positively and RBP-4 negatively onto PC3. Only PC1 was negatively associated with ISI in all ethnic groups. In the path analysis, SAT and VAT were negatively associated with ISI in Chinese and Malays without significant mediatory role of PC1. In South Asians, the relationship between VAT and ISI was mediated partly through PC1, whereas the relationship between SAT and ISI was mediated mainly through PC1.

CONCLUSIONS

The relationships between abdominal obesity, adipocytokines and insulin sensitivity differ between ethnic groups. Adiponectin, leptin, and FGF21 play a mediating role in the relationship between abdominal adiposity and insulin resistance in South Asians, but not in Malays or Chinese.

Impact of preloading either dairy or soy milk on postprandial glycemia, insulinemia and gastric emptying in healthy adults

PURPOSE

Milk protein ingestion reduces post-meal glycemia when consumed either before or together with carbohydrate foods. The aim of this study was to compare the effects of dairy and soy milk consumed either before (preload) or together with (co-ingestion) a carbohydrate (bread), on postprandial blood glucose, insulin and gastric emptying in healthy participants.

METHODS

Twelve healthy Chinese male participants were studied on five separate occasions using a randomized crossover design. White wheat bread consumed with water was used as a reference meal. Capillary and venous bloods were sampled pretest and 3.5 h post-test meal for glucose and insulin measurement. Gastric emptying was measured using real-time ultrasonography.

RESULTS

Co-ingestion of dairy milk or soy milk with bread lowered postprandial blood glucose response and glycemic index. Co-ingesting soy milk with bread increased insulin response and insulinemic index significantly compared to co-ingestion of dairy milk and preload treatments. Preloads (30 min prior to bread) significantly lowered postprandial glycemia and insulinemia compared to co-ingestion. Gastric emptying was slower after co-ingesting dairy milk with bread than after reference meal.

CONCLUSIONS

Preloading either soy milk or dairy milk results in greater reduction in glycemic response compared to co-ingestion alone. This dietary practice may have therapeutic advantage in communities consuming high GI diets. Optimal glucose control may have the potential for increasing the time of transition from prediabetes to type 2 diabetes in Asian communities.

CLINICAL TRIAL REGISTRATION

This trial was registered at clinicaltrials.gov as NCT 02151188.

Ethnic differences in insulin sensitivity and beta-cell function among Asian men

BACKGROUND AND OBJECTIVES

Lean Asian Indians are less insulin sensitive compared with Chinese and Malays, but the pancreatic beta-cell function among these ethnic groups has yet to be studied in depth. We aimed to study beta-cell function in relation to insulin sensitivity among individuals of Chinese, Malay and Asian-Indian ethnicity living in Singapore.

SUBJECTS AND METHODS

This is a sub-group analysis of 59 normoglycemic lean (body mass index (BMI) <23 kg m(-)(2)) adult males (14 Chinese, 21 Malays and 24 Asian Indians) from the Singapore Adults Metabolism Study. Insulin sensitivity was determined using fasting state indices (homeostatic model assessment-insulin resistance), the euglycemic-hyperinsulinemic clamp (ISI-clamp) and a liquid mixed-meal tolerance test (LMMTT) (Matsuda insulin sensitivity index (ISI-Mat)). Beta-cell function was assessed using fasting state indices (homeostatic model assessment-beta-cell function) and from the LMMTT (insulinogenic index and insulin secretion index). The oral disposition index (DI), a measure of beta-cell function relative to insulin sensitivity during the LMMTT, was calculated as a product of ISI-Mat and insulin secretion index.

RESULTS

Asian Indians had higher waist circumference and percent body fat than Chinese and Malays despite similar BMI. Overall, Asian Indians were the least insulin sensitive whereas the Chinese were most insulin sensitive. Asian Indians had higher beta-cell function compared with Chinese or Malays but these were not statistically different. Malays had the highest incremental area under the curve for glucose during LMMTT compared with Asian Indians and Chinese. However, there were no significant ethnic differences in the incremental insulin area under the curve. The oral DI was the lowest in Malays, followed by Asian Indians and Chinese.

CONCLUSION

Among lean Asians, Chinese are the most insulin sensitive whereas Asian Indians are the least insulin sensitive. However, Malays demonstrate higher postprandial glucose excursion with lower beta-cell response compare with Chinese or Asian Indians. The paths leading to type 2 diabetes mellitus might differ between these Asian ethnic groups.

Metformin as adjunct antituberculosis therapy

The global burden of tuberculosis (TB) morbidity and mortality remains immense. A potential new approach to TB therapy is to augment protective host immune responses. We report that the antidiabetic drug metformin (MET) reduces the intracellular growth of Mycobacterium tuberculosis (Mtb) in an AMPK (adenosine monophosphate-activated protein kinase)-dependent manner. MET controls the growth of drug-resistant Mtb strains, increases production of mitochondrial reactive oxygen species, and facilitates phagosome-lysosome fusion. In Mtb-infected mice, use of MET ameliorated lung pathology, reduced chronic inflammation, and enhanced the specific immune response and the efficacy of conventional TB drugs. Moreover, in two separate human cohorts, MET treatment was associated with improved control of Mtb infection and decreased disease severity. Collectively, these data indicate that MET is a promising candidate host-adjunctive therapy for improving the effective treatment of TB.

Smartphone apps for calculating insulin dose: a systematic assessment

BACKGROUND

Medical apps are widely available, increasingly used by patients and clinicians, and are being actively promoted for use in routine care. However, there is little systematic evidence exploring possible risks associated with apps intended for patient use. Because self-medication errors are a recognized source of avoidable harm, apps that affect medication use, such as dose calculators, deserve particular scrutiny. We explored the accuracy and clinical suitability of apps for calculating medication doses, focusing on insulin calculators for patients with diabetes as a representative use for a prevalent long-term condition.

METHODS

We performed a systematic assessment of all English-language rapid/short-acting insulin dose calculators available for iOS and Android.

RESULTS

Searches identified 46 calculators that performed simple mathematical operations using planned carbohydrate intake and measured blood glucose. While 59% (n = 27/46) of apps included a clinical disclaimer, only 30% (n = 14/46) documented the calculation formula. 91% (n = 42/46) lacked numeric input validation, 59% (n = 27/46) allowed calculation when one or more values were missing, 48% (n = 22/46) used ambiguous terminology, 9% (n = 4/46) did not use adequate numeric precision and 4% (n = 2/46) did not store parameters faithfully. 67% (n = 31/46) of apps carried a risk of inappropriate output dose recommendation that either violated basic clinical assumptions (48%, n = 22/46) or did not match a stated formula (14%, n = 3/21) or correctly update in response to changing user inputs (37%, n = 17/46). Only one app, for iOS, was issue-free according to our criteria. No significant differences were observed in issue prevalence by payment model or platform.

CONCLUSIONS

The majority of insulin dose calculator apps provide no protection against, and may actively contribute to, incorrect or inappropriate dose recommendations that put current users at risk of both catastrophic overdose and more subtle harms resulting from suboptimal glucose control. Healthcare professionals should exercise substantial caution in recommending unregulated dose calculators to patients and address app safety as part of self-management education. The prevalence of errors attributable to incorrect interpretation of medical principles underlines the importance of clinical input during app design. Systemic issues affecting the safety and suitability of higher-risk apps may require coordinated surveillance and action at national and international levels involving regulators, health agencies and app stores.