252 results found
Liu Y, Basty N, Whitcher B, et al., 2021, Genetic architecture of 11 organ traits derived from abdominal MRI using deep learning, ELIFE, Vol: 10, ISSN: 2050-084X
Bizzotto R, Jennison C, Jones AG, et al., 2021, Processes Underlying Glycemic Deterioration in Type 2 Diabetes: An IMI DIRECT Study, DIABETES CARE, Vol: 44, Pages: 511-518, ISSN: 0149-5992
Thanaj M, Basty N, Liu Y, et al., 2021, Mass Univariate Regression Analysis for Three-Dimensional Liver Image-Derived Phenotypes, Pages: 165-176, ISSN: 0302-9743
Image-derived phenotypes of abdominal organs from magnetic resonance imaging reveal variations in volume and shape and may be used to model changes in a normal versus pathological organ and improve diagnosis. Computational atlases of anatomical organs provide many advantages in quantifying and modeling differences in shape and size of organs for population imaging studies. Here we made use of liver segmentations derived from Dixon MRI for 2,730 UK Biobank participants to create 3D liver meshes. We computed the signed distances between a reference and subject-specific meshes to define the surface-to-surface (S2S) phenotype. We employed mass univariate regression analysis to compare the S2S values from the liver meshes to image-derived phenotypes specific to the liver, such as proton density fat fraction and iron concentration while adjusting for age, sex, ethnicity, body mass index and waist-to-hip ratio. Vertex-based associations in the 3D liver mesh were extracted and threshold-free cluster enhancement was applied to improve the sensitivity and stability of the statistical parametric maps. Our findings show that the 3D liver meshes are a robust method for modeling the association between anatomical, anthropometric, and phenotypic variations across the liver. This approach may be readily applied to different clinical conditions as well as extended to other abdominal organs in a larger population.
Alenaini W, Parkinson JRC, McCarthy JP, et al., 2020, Ethnic differences in body fat deposition and liver fat content in two UK-based cohorts, Obesity (Silver Spring, Md.), Vol: 28, Pages: 2142-2152, ISSN: 1071-7323
OBJECTIVE: Differences in the content and distribution of body fat and ectopic lipids may be responsible for ethnic variations in metabolic disease susceptibility. The aim of this study was to examine the ethnic distribution of body fat in two separate UK-based populations. METHODS: Anthropometry and body composition were assessed in two separate UK cohorts: the Hammersmith cohort and the UK Biobank, both comprising individuals of South Asian descent (SA), individuals of Afro-Caribbean descent (AC), and individuals of European descent (EUR). Regional adipose tissue stores and liver fat were measured by magnetic resonance techniques. RESULTS: The Hammersmith cohort (n = 747) had a mean (SD) age of 41.1 (14.5) years (EUR: 374 men, 240 women; SA: 68 men, 22 women; AC: 14 men, 29 women), and the UK Biobank (n = 9,533) had a mean (SD) age of 55.5 (7.5) years (EUR: 4,483 men, 4,873 women; SA: 80 men, 43 women, AC: 31 men, 25 women). Following adjustment for age and BMI, no significant differences in visceral adipose tissue or liver fat were observed between SA and EUR individuals in the either cohort. CONCLUSIONS: Our data, consistent across two independent UK-based cohorts, present a limited number of ethnic differences in the distribution of body fat depots associated with metabolic disease. These results suggest that the ethnic variation in susceptibility to features of the metabolic syndrome may not arise from differences in body fat.
Frost G, eriken R, Garcia Perez I, et al., 2020, Dietary metabolite profiling brings new insight into the relationship between nutrition and metabolic risk: An IMI DIRECT study, EBioMedicine, Vol: 58, Pages: 1-9, ISSN: 2352-3964
BackgroundDietary advice remains the cornerstone of prevention and management of type 2 diabetes (T2D). However, understanding the efficacy of dietary interventions is confounded by the challenges inherent in assessing free living diet. Here we profiled dietary metabolites to investigate glycaemic deterioration and cardiometabolic risk in people at risk of or living with T2D.MethodsWe analysed data from plasma collected at baseline and 18-month follow-up in individuals from the Innovative Medicines Initiative (IMI) Diabetes Research on Patient Stratification (DIRECT) cohort 1 n = 403 individuals with normal or impaired glucose regulation (prediabetic) and cohort 2 n = 458 individuals with new onset of T2D. A dietary metabolite profile model (Tpred) was constructed using multivariable regression of 113 plasma metabolites obtained from targeted metabolomics assays. The continuous Tpred score was used to explore the relationships between diet, glycaemic deterioration and cardio-metabolic risk via multiple linear regression models.FindingsA higher Tpred score was associated with healthier diets high in wholegrain (β=3.36 g, 95% CI 0.31, 6.40 and β=2.82 g, 95% CI 0.06, 5.57) and lower energy intake (β=-75.53 kcal, 95% CI -144.71, -2.35 and β=-122.51 kcal, 95% CI -186.56, -38.46), and saturated fat (β=-0.92 g, 95% CI -1.56, -0.28 and β=–0.98 g, 95% CI -1.53, -0.42 g), respectively for cohort 1 and 2. In both cohorts a higher Tpred score was also associated with lower total body adiposity and favourable lipid profiles HDL-cholesterol (β=0.07 mmol/L, 95% CI 0.03, 0.1), (β=0.08 mmol/L, 95% CI 0.04, 0.1), and triglycerides (β=-0.1 mmol/L, 95% CI -0.2, -0.03), (β=-0.2 mmol/L, 95% CI -0.3, -0.09), respectively for cohort 1 and 2. In cohort 2, the Tpred score was negatively associated with liver fat (β=-0.74%, 95% CI -0.67, -0.81), and lower fasting concentrations of HbA1c (β=-0.9 mmol/mol, 95% CI -1.5, -0.1), glu
Machann J, Stefan N, Wagner R, et al., 2020, Normalized Indices Derived from Visceral Adipose Mass Assessed by Magnetic Resonance Imaging and Their Correlation with Markers for Insulin Resistance and Prediabetes, NUTRIENTS, Vol: 12
Whyte MB, Shojaee-Moradie F, Sharaf SE, et al., 2020, HDL-apoA-I kinetics in response to 16 wk of exercise training in men with nonalcoholic fatty liver disease., American Journal of Physiology: Endocrinology and Metabolism, Vol: 318, Pages: E839-E847, ISSN: 0193-1849
Nonalcoholic fatty liver disease (NAFLD) is characterized by low-circulating concentration of high-density lipoprotein cholesterol (HDL-C) and raised triacylglycerol (TAG). Exercise reduces hepatic fat content, improves insulin resistance and increases clearance of very-low-density lipoprotein-1 (VLDL1). However, the effect of exercise on TAG and HDL-C metabolism is unknown. We randomized male participants to 16 wk of supervised, moderate-intensity aerobic exercise (n = 15), or conventional lifestyle advice (n = 12). Apolipoprotein A-I (apoA-I) and VLDL-TAG and apolipoprotein B (apoB) kinetics were investigated using stable isotopes (1-[13C]-leucine and 1,1,2,3,3-2H5 glycerol) pre- and postintervention. Participants underwent MRI/spectroscopy to assess changes in visceral fat. Results are means ± SD. At baseline, there were no differences between exercise and control groups for age (52.4 ± 7.5 vs. 52.8 ± 10.3 yr), body mass index (BMI: 31.6 ± 3.2 vs. 31.7 ± 3.6 kg/m2), and waist circumference (109.3 ± 7.5 vs. 110.0 ± 13.6 cm). Percentage of liver fat was 23.8 (interquartile range 9.8-32.5%). Exercise reduced body weight (101.3 ± 10.2 to 97.9 ± 12.2 kg; P < 0.001) and hepatic fat content [from 19.6%, interquartile range (IQR) 14.6-36.1% to 8.9% (4.4-17.8%); P = 0.001] and increased the fraction HDL-C concentration (measured following ultracentrifugation) and apoA-I pool size with no change in the control group. However, plasma and VLDL1-TAG concentrations and HDL-apoA-I fractional catabolic rate (FCR) and production rate (PR) did not change significantly with exercise. Both at baseline (all participants) and after exercise there was an inverse correlation between apoA-I pool size and VLDL-TAG and -apoB pool size. The modest effect of exercise on HDL metabolism may be explained b
Atabaki-Pasdar N, Ohlsson M, Vinuela A, et al., 2020, Predicting and elucidating the etiology of fatty liver disease: A machine learning modeling and validation study in the IMI DIRECT cohorts, PLoS Medicine, Vol: 17, Pages: 1-27, ISSN: 1549-1277
BackgroundNon-alcoholic fatty liver disease (NAFLD) is highly prevalent and causes serious health complications in individuals with and without type 2 diabetes (T2D). Early diagnosis of NAFLD is important, as this can help prevent irreversible damage to the liver and, ultimately, hepatocellular carcinomas. We sought to expand etiological understanding and develop a diagnostic tool for NAFLD using machine learning.Methods and findingsWe utilized the baseline data from IMI DIRECT, a multicenter prospective cohort study of 3,029 European-ancestry adults recently diagnosed with T2D (n = 795) or at high risk of developing the disease (n = 2,234). Multi-omics (genetic, transcriptomic, proteomic, and metabolomic) and clinical (liver enzymes and other serological biomarkers, anthropometry, measures of beta-cell function, insulin sensitivity, and lifestyle) data comprised the key input variables. The models were trained on MRI-image-derived liver fat content (<5% or ≥5%) available for 1,514 participants. We applied LASSO (least absolute shrinkage and selection operator) to select features from the different layers of omics data and random forest analysis to develop the models. The prediction models included clinical and omics variables separately or in combination. A model including all omics and clinical variables yielded a cross-validated receiver operating characteristic area under the curve (ROCAUC) of 0.84 (95% CI 0.82, 0.86; p < 0.001), which compared with a ROCAUC of 0.82 (95% CI 0.81, 0.83; p < 0.001) for a model including 9 clinically accessible variables. The IMI DIRECT prediction models outperformed existing noninvasive NAFLD prediction tools. One limitation is that these analyses were performed in adults of European ancestry residing in northern Europe, and it is unknown how well these findings will translate to people of other ancestries and exposed to environmental risk factors that differ from those of the present cohort. Another key limitation of
Littlejohns TJ, Holliday J, Gibson LM, et al., 2020, The UK Biobank imaging enhancement of 100,000 participants: rationale, data collection, management and future directions, Nature Communications, Vol: 11, ISSN: 2041-1723
UK Biobank is a population-based cohort of half a million participants aged 40-69 years recruited between 2006 and 2010. In 2014, UK Biobank started the world's largest multi-modal imaging study, with the aim of re-inviting 100,000 participants to undergo brain, cardiac and abdominal magnetic resonance imaging, dual-energy X-ray absorptiometry and carotid ultrasound. The combination of large-scale multi-modal imaging with extensive phenotypic and genetic data offers an unprecedented resource for scientists to conduct health-related research. This article provides an in-depth overview of the imaging enhancement, including the data collected, how it is managed and processed, and future directions.
Koivula RW, Atabaki-Pasdar N, Giordano GN, et al., 2020, The role of physical activity in metabolic homeostasis before and after the onset of type 2 diabetes: an IMI DIRECT study, Diabetologia, Vol: 63, Pages: 744-756, ISSN: 0012-186X
Aims/hypothesisIt is well established that physical activity, abdominal ectopic fat and glycaemic regulation are related but the underlying structure of these relationships is unclear. The previously proposed twin-cycle hypothesis (TC) provides a mechanistic basis for impairment in glycaemic control through the interactions of substrate availability, substrate metabolism and abdominal ectopic fat accumulation. Here, we hypothesise that the effect of physical activity in glucose regulation is mediated by the twin-cycle. We aimed to examine this notion in the Innovative Medicines Initiative Diabetes Research on Patient Stratification (IMI DIRECT) Consortium cohorts comprised of participants with normal or impaired glucose regulation (cohort 1: N ≤ 920) or with recently diagnosed type 2 diabetes (cohort 2: N ≤ 435).MethodsWe defined a structural equation model that describes the TC and fitted this within the IMI DIRECT dataset. A second model, twin-cycle plus physical activity (TC-PA), to assess the extent to which the effects of physical activity in glycaemic regulation are mediated by components in the twin-cycle, was also fitted. Beta cell function, insulin sensitivity and glycaemic control were modelled from frequently sampled 75 g OGTTs (fsOGTTs) and mixed-meal tolerance tests (MMTTs) in participants without and with diabetes, respectively. Abdominal fat distribution was assessed using MRI, and physical activity through wrist-worn triaxial accelerometry. Results are presented as standardised beta coefficients, SE and p values, respectively.ResultsThe TC and TC-PA models showed better fit than null models (TC: χ2 = 242, p = 0.004 and χ2 = 63, p = 0.001 in cohort 1 and 2, respectively; TC-PA: χ2 = 180, p = 0.041 and χ2 = 60, p = 0.008 in cohort 1 and 2, respectively). The association of physical activity wi
Mani B, Puzziferri N, He Z, et al., 2019, LEAP2 changes with body mass and food intake in humans and mice, Journal of Clinical Investigation, Vol: 129, Pages: 3909-3923, ISSN: 0021-9738
Acyl-ghrelin administration increases food intake, body weight, and blood glucose. In contrast, mice lacking ghrelin or ghrelin receptors (GHSRs) exhibit life-threatening hypoglycemia during starvation-like conditions, but do not consistently exhibit overt metabolic phenotypes when given ad libitum food access. These results, and findings of ghrelin resistance in obese states, imply nutritional state dependence of ghrelin’s metabolic actions. Here, we hypothesized that liver-enriched antimicrobial peptide-2 (LEAP2), a recently characterized endogenous GHSR antagonist, blunts ghrelin action during obese states and postprandially. To test this hypothesis, we determined changes in plasma LEAP2 and acyl-ghrelin due to fasting, eating, obesity, Roux-en-Y gastric bypass (RYGB), vertical sleeve gastrectomy (VSG), oral glucose administration, and type 1 diabetes mellitus (T1DM) using humans and/or mice. Our results suggest that plasma LEAP2 is regulated by metabolic status: its levels increased with body mass and blood glucose and decreased with fasting, RYGB, and in postprandial states following VSG. These changes were mostly opposite of those of acyl-ghrelin. Furthermore, using electrophysiology, we showed that LEAP2 both hyperpolarizes and prevents acyl-ghrelin from activating arcuate NPY neurons. We predict that the plasma LEAP2/acyl-ghrelin molar ratio may be a key determinant modulating acyl-ghrelin activity in response to body mass, feeding status, and blood glucose.
Wilman HR, Parisinos CA, Atabaki-Pasdar N, et al., 2019, Genetic studies of abdominal MRI data identify genes regulating hepcidin as major determinants of liver iron concentration, Journal of Hepatology, Vol: 71, Pages: 594-602, ISSN: 0168-8278
BACKGROUND & AIMS: Excess liver iron content is common and is linked to the risk of hepatic and extrahepatic diseases. We aimed to identify genetic variants influencing liver iron content and use genetics to understand its link to other traits and diseases. METHODS: First, we performed a genome-wide association study (GWAS) in 8,289 individuals from UK Biobank, whose liver iron level had been quantified by magnetic resonance imaging, before validating our findings in an independent cohort (n = 1,513 from IMI DIRECT). Second, we used Mendelian randomisation to test the causal effects of 25 predominantly metabolic traits on liver iron content. Third, we tested phenome-wide associations between liver iron variants and 770 traits and disease outcomes. RESULTS: We identified 3 independent genetic variants (rs1800562 [C282Y] and rs1799945 [H63D] in HFE and rs855791 [V736A] in TMPRSS6) associated with liver iron content that reached the GWAS significance threshold (p <5 × 10-8). The 2 HFE variants account for ∼85% of all cases of hereditary haemochromatosis. Mendelian randomisation analysis provided evidence that higher central obesity plays a causal role in increased liver iron content. Phenome-wide association analysis demonstrated shared aetiopathogenic mechanisms for elevated liver iron, high blood pressure, cirrhosis, malignancies, neuropsychiatric and rheumatological conditions, while also highlighting inverse associations with anaemias, lipidaemias and ischaemic heart disease. CONCLUSION: Our study provides genetic evidence that mechanisms underlying higher liver iron content are likely systemic rather than organ specific, that higher central obesity is causally associated with higher liver iron, and that liver iron shares common aetiology with multiple metabolic and non-metabolic diseases. LAY SUMMARY: Excess liver iron content is common and is associated with liver diseases and metabolic diseases including diabetes, high blood pressure, and heart
Koivula RW, Forgie IM, Kurbasic A, et al., 2019, Discovery of biomarkers for glycaemic deterioration before and after the onset of type 2 diabetes: descriptive characteristics of the epidemiological studies within the IMI DIRECT Consortium., Diabetologia, Vol: 62, Pages: 1601-1615, ISSN: 0012-186X
AIMS/HYPOTHESIS: Here, we describe the characteristics of the Innovative Medicines Initiative (IMI) Diabetes Research on Patient Stratification (DIRECT) epidemiological cohorts at baseline and follow-up examinations (18, 36 and 48 months of follow-up). METHODS: From a sampling frame of 24,682 adults of European ancestry enrolled in population-based cohorts across Europe, participants at varying risk of glycaemic deterioration were identified using a risk prediction algorithm (based on age, BMI, waist circumference, use of antihypertensive medication, smoking status and parental history of type 2 diabetes) and enrolled into a prospective cohort study (n = 2127) (cohort 1, prediabetes risk). We also recruited people from clinical registries with type 2 diabetes diagnosed 6-24 months previously (n = 789) into a second cohort study (cohort 2, diabetes). Follow-up examinations took place at ~18 months (both cohorts) and at ~48 months (cohort 1) or ~36 months (cohort 2) after baseline examinations. The cohorts were studied in parallel using matched protocols across seven clinical centres in northern Europe. RESULTS: Using ADA 2011 glycaemic categories, 33% (n = 693) of cohort 1 (prediabetes risk) had normal glucose regulation and 67% (n = 1419) had impaired glucose regulation. Seventy-six per cent of participants in cohort 1 was male. Cohort 1 participants had the following characteristics (mean ± SD) at baseline: age 62 (6.2) years; BMI 27.9 (4.0) kg/m2; fasting glucose 5.7 (0.6) mmol/l; 2 h glucose 5.9 (1.6) mmol/l. At the final follow-up examination the participants' clinical characteristics were as follows: fasting glucose 6.0 (0.6) mmol/l; 2 h OGTT glucose 6.5 (2.0) mmol/l. In cohort 2 (diabetes), 66% (n = 517) were treated by lifestyle modification and 34% (n = 272) were treated with metformin plus lifestyle modification at enro
Evangelou E, Gao H, Blakeley P, et al., 2019, New alcohol-related genes suggest shared genetic mechanisms with neuropsychiatric disorders, Nature Human Behaviour, Vol: 3, Pages: 950-961, ISSN: 2397-3374
Excessive alcohol consumption is one of the main causes of death and disability worldwide. Alcohol consumption is a heritable complex trait. Here we conducted a meta-analysis of genome-wide association studies of alcohol consumption (g d−1) from the UK Biobank, the Alcohol Genome-Wide Consortium and the Cohorts for Heart and Aging Research in Genomic Epidemiology Plus consortia, collecting data from 480,842 people of European descent to decipher the genetic architecture of alcohol intake. We identified 46 new common loci and investigated their potential functional importance using magnetic resonance imaging data and gene expression studies. We identify genetic pathways associated with alcohol consumption and suggest genetic mechanisms that are shared with neuropsychiatric disorders such as schizophrenia.
Chambers E, Byrne C, Rugyendo A, et al., 2019, The effects of dietary supplementation with inulin and inulin-propionate ester on hepatic steatosis in adults with non-alcoholic fatty liver disease, Diabetes, Obesity and Metabolism, Vol: 21, Pages: 372-376, ISSN: 1462-8902
The short chain fatty acid (SCFA) propionate, produced through fermentation of dietary fibre by the gut microbiota, has been shown to alter hepatic metabolic processes that reduce lipid storage. We aimed to investigate the impact of raising colonic propionate production on hepatic steatosis in adults with non‐alcoholic fatty liver disease (NAFLD). Eighteen adults were randomised to receive 20g/day of an inulin‐propionate ester (IPE), designed to deliver propionate to the colon, or an inulin‐control for 42‐days in a parallel design. The change in intrahepatocellular lipid (IHCL) following the supplementation period was not different between groups (P=0.082), however IHCL significantly increased within the inulin‐control group (20.9±2.9 to 26.8±3.9%; P=0.012; n=9), which was not observed within the IPE group (22.6±6.9 to 23.5±6.8%; P=0.635; n=9). The predominant SCFA from colonic fermentation of inulin is acetate, which in a background of NAFLD and a hepatic metabolic profile that promotes fat accretion, may provide surplus lipogenic substrate to the liver. The increased colonic delivery of propionate from IPE appears to attenuate this acetate‐mediated increase in IHCL.
Ji Y, Yiorkas AM, Frau F, et al., 2019, Genome-wide and abdominal MRI data provide evidence that a genetically determined favorable adiposity phenotype is characterized by lower ectopic liver fat and lower risk of type 2 diabetes, heart disease, and hypertension, Diabetes, Vol: 68, Pages: 207-219, ISSN: 0012-1797
Recent genetic studies have identified alleles associated with opposite effects on adiposity and risk of type 2 diabetes. We aimed to identify more of these variants and test the hypothesis that such favorable adiposity alleles are associated with higher subcutaneous fat and lower ectopic fat. We combined MRI data with genome-wide association studies of body fat percentage (%) and metabolic traits. We report 14 alleles, including 7 newly characterized alleles, associated with higher adiposity but a favorable metabolic profile. Consistent with previous studies, individuals carrying more favorable adiposity alleles had higher body fat % and higher BMI but lower risk of type 2 diabetes, heart disease, and hypertension. These individuals also had higher subcutaneous fat but lower liver fat and a lower visceral-to-subcutaneous adipose tissue ratio. Individual alleles associated with higher body fat % but lower liver fat and lower risk of type 2 diabetes included those in PPARG, GRB14, and IRS1, whereas the allele in ANKRD55 was paradoxically associated with higher visceral fat but lower risk of type 2 diabetes. Most identified favorable adiposity alleles are associated with higher subcutaneous and lower liver fat, a mechanism consistent with the beneficial effects of storing excess triglycerides in metabolically low-risk depots.
So P-W, Ekonomou A, Galley K, et al., 2019, Intraperitoneal delivery of acetate-encapsulated liposomal nanoparticles for neuroprotection of the penumbra in a rat model of ischemic stroke, INTERNATIONAL JOURNAL OF NANOMEDICINE, Vol: 14, Pages: 1979-1991, ISSN: 1178-2013
Fiamoncini J, Rundle M, Gibbons H, et al., 2018, Plasma metabolome analysis identifies distinct human metabotypes in the postprandial state with different susceptibility to weight loss-mediated metabolic improvements, FASEB Journal, Vol: 32, Pages: 5447-5458, ISSN: 0892-6638
Health has been defined as the capability of the organism to adapt to challenges. In this study, we tested to what extent comprehensively phenotyped individuals reveal differences in metabolic responses to a standardized mixed meal tolerance test (MMTT) and how these responses change when individuals experience moderate weight loss. Metabolome analysis was used in 70 healthy individuals. with profiling of ∼300 plasma metabolites during an MMTT over 8 h. Multivariate analysis of plasma markers of fatty acid catabolism identified 2 distinct metabotype clusters (A and B). Individuals from metabotype B showed slower glucose clearance, had increased intra-abdominal adipose tissue mass and higher hepatic lipid levels when compared with individuals from metabotype A. An NMR-based urine analysis revealed that these individuals also to have a less healthy dietary pattern. After a weight loss of ∼5.6 kg over 12 wk, only the subjects from metabotype B showed positive changes in the glycemic response during the MMTT and in markers of metabolic diseases. Our study in healthy individuals demonstrates that more comprehensive phenotyping can reveal discrete metabotypes with different outcomes in a dietary intervention and that markers of lipid catabolism in plasma could allow early detection of the metabolic syndrome.—Fiamoncini, J., Rundle, M., Gibbons, H., Thomas, E. L., Geillinger-Kästle, K., Bunzel, D., Trezzi, J.-P., Kiselova-Kaneva, Y., Wopereis, S., Wahrheit, J., Kulling, S. E., Hiller, K., Sonntag, D., Ivanova, D., van Ommen, B., Frost, G., Brennan, L., Bell, J. Daniel, H. Plasma metabolome analysis identifies distinct human metabotypes in the postprandial state with different susceptibility to weight loss–mediated metabolic improvements.One of the key features of human metabolism is its plasticity and capacity to regain homeostasis upon a disturbance such as acute stress, starvation, or food intake (1). In this regard it has been proposed that heal
Borga M, West J, Bell JD, et al., 2018, Advanced body composition assessment: from body mass index to body composition profiling, JOURNAL OF INVESTIGATIVE MEDICINE, Vol: 66, Pages: 887-895, ISSN: 1081-5589
This paper gives a brief overview of common non-invasive techniques for body composition analysis and a more in-depth review of a body composition assessment method based on fat-referenced quantitative MRI. Earlier published studies of this method are summarized, and a previously unpublished validation study, based on 4753 subjects from the UK Biobank imaging cohort, comparing the quantitative MRI method with dual-energy X-ray absorptiometry (DXA) is presented. For whole-body measurements of adipose tissue (AT) or fat and lean tissue (LT), DXA and quantitative MRIs show excellent agreement with linear correlation of 0.99 and 0.97, and coefficient of variation (CV) of 4.5 and 4.6 per cent for fat (computed from AT) and LT, respectively, but the agreement was found significantly lower for visceral adipose tissue, with a CV of >20 per cent. The additional ability of MRI to also measure muscle volumes, muscle AT infiltration and ectopic fat, in combination with rapid scanning protocols and efficient image analysis tools, makes quantitative MRI a powerful tool for advanced body composition assessment.
Cobbold JFL, Atkinson S, Marchesi JR, et al., 2018, Rifaximin in non-alcoholic steatohepatitis: An open-label pilot study, HEPATOLOGY RESEARCH, Vol: 48, Pages: 69-77, ISSN: 1386-6346
AimGut microbial dysbiosis is implicated in the pathogenesis of non‐alcoholic steatohepatitis (NASH). We investigated downstream effects of gut microbiota modulation on markers of hepatic inflammation, steatosis, and hepatic and peripheral insulin sensitivity in patients with NASH using rifaximin therapy.MethodsPatients with biopsy‐proven NASH and elevated aminotransferase values were included in this open‐label pilot study, all receiving 6 weeks rifaximin 400 mg twice daily, followed by a 6‐week observation period. The primary endpoint was change in alanine aminotransferase (ALT) after 6 weeks of rifaximin. Secondary endpoints were change in hepatic lipid content and insulin sensitivity measured with a hyperinsulinemic–euglycemic clamp.ResultsFifteen patients (13 men and 2 women) with a median (range) age of 46 (32–63) years were included. Seven had diabetes on oral hypoglycemic medications and 8 had no diabetes. After 6 weeks of therapy, no differences were seen in ALT (55 [33–191] vs. 63 [41–218] IU/L, P = 0.41), peripheral glucose uptake (28.9 [19.4–48.3] to 25.5 [17.7–47.9] μmol/kg/min, P = 0.30), hepatic insulin sensitivity (35.2 [15.3–51.7]% vs. 30.0 [10.8–50.5]%, P = 0.47), or hepatic lipid content (21.6 [2.2–46.2]% vs. 24.8 [1.7–59.3]%, P = 0.59) before and after rifaximin treatment. After 12 weeks from baseline, serum ALT increased to 83 (30–217) IU/L, P = 0.02. There was a significant increase in the homeostasis model assessment–estimated insulin resistance index (P = 0.05). The urinary metabolic profile indicated a significant reduction in urinary hippurate with treatment, which reverted to baseline after cessation of rifaximin, although there was no consistent difference in relative abundance of fecal microbiota with treatment.ConclusionThese data do not indicate a beneficial effect of rifaximin i
Shafique M, Russell S, Murdoch S, et al., 2017, Dietary intake in people consuming a low-carbohydrate diet in the UK Biobank., J Hum Nutr Diet
BACKGROUND: Low-carbohydrate diets are becoming increasingly popular, although their dietary quality outside of clinical studies is unknown. A previous study analysed the dietary intake in people consuming a reduced-carbohydrate diet (<40% calories). However, it is not clear what foods people consume when carbohydrate is reduced to below 26% of total calories. METHODS: In the present cross-sectional study, the dietary and nutrient intake collected via up to five consecutive 24-h dietary recalls and a food frequency questionnaire of 444 individuals (aged 46-79 years) consuming <26% of calories from carbohydrate (LCHO) was compared with that of 131 897 individuals consuming ≥45% calories from carbohydrate (NCHO) using the UK Biobank Dataset. Absolute cut-offs to define the low-carbohydrate group (<130 g day-1 ; n = 1953 versus ≥225 g day-1 , n = 113 036) were also used. RESULTS: Both NCHO (>45% calories and ≥225 g) groups consumed significantly more high-sugar, high-fat snacks [median 6.0, interquartile range (IQR) = 2.0-11.0 and median 6.0, IQR = 3.0-11.8, respectively) compared to the LCHO (<26% calories and <130 g) groups (median 0, IQR = 0-2.8 and median 1, IQR = 0-3.8, respectively) (P < 0.0001). Both LCHO groups reported consuming significantly more red meat, oily fish, nuts and seeds but fewer fruits, vegetables and pulses compared to the NCHO groups. In general, the consumption of oily fish, nuts, seeds and pulses was low across the whole cohort and differences in intake between the LCHO and NCHO groups were small. After adjusting for socio-economic status, most differences remained. CONCLUSIONS: Carbohydrate restriction is associated with both beneficial and potentially deleterious dietary changes compared to a normal carbohydrate intake.
Umpleby AM, Shojaee-Moradie F, Fielding B, et al., 2017, Impact of liver fat on the differential partitioning of hepatic triacylglycerol into VLDL subclasses on high and low sugar diets., Clinical Science, Vol: 131, Pages: 2561-2573, ISSN: 0143-5221
Dietary sugars are linked to the development of non-alcoholic fatty liver disease (NAFLD) and dyslipidaemia, but it is unknown if NAFLD itself influences the effects of sugars on plasma lipoproteins. To study this further, men with NAFLD (n = 11) and low liver fat 'controls' (n = 14) were fed two iso-energetic diets, high or low in sugars (26% or 6% total energy) for 12 weeks, in a randomised, cross-over design. Fasting plasma lipid and lipoprotein kinetics were measured after each diet by stable isotope trace-labelling.There were significant differences in the production and catabolic rates of VLDL subclasses between men with NAFLD and controls, in response to the high and low sugar diets. Men with NAFLD had higher plasma concentrations of VLDL1-triacylglycerol (TAG) after the high (P<0.02) and low sugar (P<0.0002) diets, a lower VLDL1-TAG fractional catabolic rate after the high sugar diet (P<0.01), and a higher VLDL1-TAG production rate after the low sugar diet (P<0.01), relative to controls. An effect of the high sugar diet, was to channel hepatic TAG into a higher production of VLDL1-TAG (P<0.02) in the controls, but in contrast, a higher production of VLDL2-TAG (P<0.05) in NAFLD. These dietary effects on VLDL subclass kinetics could be explained, in part, by differences in the contribution of fatty acids from intra-hepatic stores, and de novo lipogenesis. The present study provides new evidence that liver fat accumulation leads to a differential partitioning of hepatic TAG into large and small VLDL subclasses, in response to high and low intakes of sugars.
Brody LP, Sahuri-Arisoylu M, Parkinson JR, et al., 2017, Cationic lipid-based nanoparticles mediate functional delivery of acetate to tumor cells in vivo leading to significant anticancer effects, International Journal of Nanomedicine, Vol: 12, Pages: 6677-6685, ISSN: 1176-9114
Metabolic reengineering using nanoparticle delivery represents an innovative therapeutic approach to normalizing the deregulation of cellular metabolism underlying many diseases, including cancer. Here, we demonstrated a unique and novel application to the treatment of malignancy using a short-chain fatty acid (SCFA)-encapsulated lipid-based delivery system – liposome-encapsulated acetate nanoparticles for cancer applications (LITA-CAN). We assessed chronic in vivo administration of our nanoparticle in three separate murine models of colorectal cancer. We demonstrated a substantial reduction in tumor growth in the xenograft model of colorectal cancer cell lines HT-29, HCT-116 p53+/+ and HCT-116 p53-/-. Nanoparticle-induced reductions in histone deacetylase gene expression indicated a potential mechanism for these anti-proliferative effects. Together, these results indicated that LITA-CAN could be used as an effective direct or adjunct therapy to treat malignant transformation in vivo.
Hameed S, Patterson M, Dhillo W, et al., 2017, Thyroid hormone receptor beta in the ventromedial hypothalamus is essential for the physiological regulation of food intake and body weight, Cell Reports, Vol: 19, Pages: 2202-2209, ISSN: 2211-1247
The obesity epidemic is a significant global health issue. Improved understanding of the mechanisms that regulate appetite and body weight will provide the rationale for the design of anti-obesity therapies. Thyroid hormones play a key role in metabolic homeostasis through their interaction with thyroid hormone receptors (TRs), which function as ligand-inducible transcription factors. The TR-beta isoform (TRβ) is expressed in the ventromedial hypothalamus (VMH), a brain area important for control of energy homeostasis. Here, we report that selective knockdown of TRβ in the VMH of adult mice results in severe obesity due to hyperphagia and reduced energy expenditure. The observed increase in body weight is of a similar magnitude to murine models of the most extreme forms of monogenic obesity. These data identify TRβ in the VMH as a major physiological regulator of food intake and energy homeostasis.
Wilman HR, Kelly M, Garratt S, et al., 2017, Characterisation of liver fat in the UK Biobank cohort, PLOS ONE, Vol: 12, ISSN: 1932-6203
Non-alcoholicfattyliverdiseaseandtheriskof progressionto steatohepatitis,cirrhosisandhepatocellularcarcinomahavebeenidentifiedasmajorpublichealthconcerns.Wehavedemonstratedthefeasibilityandpotentialvalueof measuringliverfatcontentbymagneticresonanceimaging(MRI)in a largepopulationin thisstudyof 4,949participants(aged45–73years)in theUKBiobankimagingenhancement. Despiterequirementsforonlya single( 3min)scanof eachsubject,liverfatwasableto bemeasuredastheMRIprotondensityfatfraction(PDFF)withanoverallsuccessrateof 96.4%.Theoverallhepaticfatdistributionwascentredbetween1–2%,andwashighlyskewedtowardshigherfatcontent.ThemeanPDFFwas3.91%,andmedian2.11%.Analysisof PDFFin conjunctionwithotherdatafieldsavailablefromtheUKBiobankResourceshowedassociationsof increasedliverfatwithgreaterage,BMI,weightgain,highbloodpressureandType2 diabetes.SubjectswithBMIlessthan25kg/m2hada lowrisk(5%)of highliverfat(PDFF>5.5%),whereasin thehigherBMIpopulation(>30kg/m2) theprevalenceof highliverfatwasapproximately1 in 3. Thesedatasuggestthatpopulationscreeningto identifypeoplewithhighPDFFis possibleandcouldbecosteffective.MRIbasedPDFFis aneffectivemethodforthis.Finally,althoughcrosssectional,thisstudysuggeststheutilityof thePDFFmeasurement withinUKBiobank,particularlyforapplicationsto elucidatingriskfactorsthroughassociationswithprospec-tivelyacquireddataonclinicaloutcomesof liverdiseases,includingnon-alcoholicfattyliverdisease.
Henley AB, Yang L, Chuang K-L, et al., 2017, Withania somnifera Root Extract Enhances Chemotherapy through ‘Priming’, PLoS ONE, Vol: 12, ISSN: 1932-6203
Withania somnifera extracts are known for their anti-cancerous, anti-inflammatory and antioxidativeproperties. One of their mechanisms of actions is to modulate mitochondrial functionthrough increasing oxidative stress. Recently ‘priming’ has been suggested as apotential mechanism for enhancing cancer cell death. In this study we demonstrate that‘priming’, in HT-29 colon cells, with W. somnifera root extract increased the potency of thechemotherapeutic agent cisplatin. We have also showed the W. somnifera root extractenhanced mitochondrial dysfunction and that the underlying mechanism of ‘priming’ wasselectively through increased ROS. Moreover, we showed that this effect was not seen innon-cancerous cells.
Schofield S, Parkinson J, Henley A, et al., 2017, Metabolic dysfunction following weight cycling in male mice, International Journal of Obesity, Vol: 41, Pages: 402-411, ISSN: 0307-0565
Background: Combatting overweight or obesity can lead to large fluctuations in an individual’s body weight, often referred to as weight cycling or ‘yo-yo’ dieting. Current evidence regarding the potentially damaging effects of these changes is conflicting.Methods: Here, we assess the metabolic effects of weight cycling in a murine model, comprising three dietary switches to normal or high-fat diets at 6 week intervals; male C57BL/6 mice were fed either a control (C) or high-fat (F) diet for 6 weeks (n=140/group). C and F groups were then either maintained on their initial diet (CC and FF, respectively) or switched to a high-fat (CF) or control (FC) diet (n=35/group). For the final 6 week interval, CC and CF groups were returned to the control diet (CCC and CFC groups), while FC and FF groups were placed on a high-fat diet (FCF and FFF) (n=28/group).Results: For the majority of metabolic outcomes changes aligned with dietary switches; however, assessment of neuropeptides and receptors involved in appetite regulation and reward signalling pathways reveal variable patterns of expression. Furthermore, we demonstrate that multiple cycling events leads to a significant increase in internal fat deposition, even when compared with animals maintained on a high-fat diet (internal fat: FCF: 7.4±0.2 g vs FFF: 5.6±0.2 g; P<0.01).Conclusions: Increased internal adipose tissue is strongly linked to the development of metabolic syndrome associated conditions such as type 2 diabetes, cardiovascular disease and hypertension. Although further work will be required to elucidate the mechanisms underlying the neuronal control of energy homoeostasis, these studies provide a causative link between weight cycling and adverse health.
Lee S, Norheim F, Langleite TM, et al., 2016, Effect of energy restriction and physical exercise intervention on phenotypic flexibility as examined by transcriptomics analyses of mRNA from adipose tissue and whole body magnetic resonance imaging., Physiological Reports, Vol: 4, ISSN: 2051-817X
Overweight and obesity lead to changes in adipose tissue such as inflammation and reduced insulin sensitivity. The aim of this study was to assess how altered energy balance by reduced food intake or enhanced physical activity affect these processes. We studied sedentary subjects with overweight/obesity in two intervention studies, each lasting 12 weeks affecting energy balance either by energy restriction (~20% reduced intake of energy from food) in one group, or by enhanced energy expenditure due to physical exercise (combined endurance- and strength-training) in the other group. We monitored mRNA expression by microarray and mRNA sequencing from adipose tissue biopsies. We also measured several plasma parameters as well as fat distribution with magnetic resonance imaging and spectroscopy. Comparison of microarray and mRNA sequencing showed strong correlations, which were also confirmed using RT-PCR In the energy restricted subjects (body weight reduced by 5% during a 12 weeks intervention), there were clear signs of enhanced lipolysis as monitored by mRNA in adipose tissue as well as plasma concentration of free-fatty acids. This increase was strongly related to increased expression of markers for M1-like macrophages in adipose tissue. In the exercising subjects (glucose infusion rate increased by 29% during a 12-week intervention), there was a marked reduction in the expression of markers of M2-like macrophages and T cells, suggesting that physical exercise was especially important for reducing inflammation in adipose tissue with insignificant reduction in total body weight. Our data indicate that energy restriction and physical exercise affect energy-related pathways as well as inflammatory processes in different ways, probably related to macrophages in adipose tissue.
Brooks L, Viardot A, Tsakmaki A, et al., 2016, Fermentable carbohydrate stimulates FFAR2-dependent colonic PYY cell expansion to increase satiety, Molecular Metabolism, Vol: 6, Pages: 48-60, ISSN: 2212-8778
ObjectiveDietary supplementation with fermentable carbohydrate protects against body weight gain. Fermentation by the resident gut microbiota produces short-chain fatty acids, which act at free fatty acid receptor 2 (FFAR2). Our aim was to test the hypothesis that FFAR2 is important in regulating the beneficial effects of fermentable carbohydrate on body weight and to understand the role of gut hormones PYY and GLP-1. MethodsWild-type or Ffar2-/-mice were fed an inulin supplemented or control diet. Mice were metabolically characterised and gut hormone concentrations, enteroendocrine cell density measurements were carried out. Intestinal organoids and colonic cultures were utilised to substantiate the in vivo findings.ResultsWe provide new mechanistic insight into how fermentable carbohydrate regulates metabolism. Using mice that lack FFAR2, we demonstrate that the fermentable carbohydrate, inulin, acts via this receptor to drive an 87% increase in the density of cells that produce the appetite-supressing hormone peptide YY (PYY), reduce food intake and prevent diet-induced obesity. Conclusion Our results demonstrate that FFAR2 is predominantly involved in regulating the effects of fermentable carbohydrate on metabolism and does so, in part, by enhancing PYY cell density and release. This highlights the potential for targeting enteroendocrine cell differentiation to treat obesity.
Shojaee-Moradie F, Cuthbertson DJ, Barrett M, et al., 2016, Exercise Training Reduces Liver Fat and Increases Rates of VLDL Clearance But Not VLDL Production in NAFLD, JOURNAL OF CLINICAL ENDOCRINOLOGY & METABOLISM, Vol: 101, Pages: 4219-4228, ISSN: 0021-972X
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