Adiponectin is inversely associated with intramyocellular and intrahepatic lipids in obese premenopausal women

The GH/IGF-1 Axis Is Associated With Intrahepatic Lipid Content and Hepatocellular Damage in Overweight/Obesity

CONTEXT

Obesity is a state of relative growth hormone (GH) deficiency, and GH has been identified as a candidate disease-modifying target in nonalcoholic fatty liver disease (NAFLD) because of its lipolytic and anti-inflammatory properties. However, the GH/IGF-1 axis has not been well characterized in NAFLD.

OBJECTIVE

We aimed to investigate serum GH and IGF-1 levels in relation to intrahepatic lipid content (IHL) and markers of hepatocellular damage and fibrosis in NAFLD.

METHODS

This cross-sectional study included 102 adults (43% women; age 19-67; BMI ≥ 25 kg/m2) without type 2 diabetes. IHL was measured by magnetic resonance spectroscopy; NAFLD was defined by ≥ 5% IHL. Peak-stimulated GH in response to GH releasing hormone and arginine was assessed as was serum IGF-1 (LC/MS).

RESULTS

There was no difference in mean age, BMI, or sex distribution in NAFLD vs controls. Mean (± SD) IHL was higher in NAFLD vs controls (21.8 ± 13.3% vs 2.9 ± 1.1%, P < 0.0001). Mean peak-stimulated GH was lower in NAFLD vs controls (9.0 ± 6.3 vs 15.4 ± 11.2 ng/mL, P = 0.003), including after controlling for age, sex, visceral adipose tissue, and fasting glucose. In a stepwise model, peak-stimulated GH predicted 14.6% of the variability in IHL (P = 0.004). Higher peak-stimulated GH was also associated with lower ALT. Higher serum IGF-1 levels were associated with lower risk of liver fibrosis by Fibrosis-4 scores.

CONCLUSION

Individuals with NAFLD have lower peak-stimulated GH levels but similar IGF-1 levels as compared to controls. Higher peak-stimulated GH levels are associated with lower IHL and less hepatocellular damage. Higher IGF-1 levels are associated with more favorable fibrosis risk scores. These data implicate GH and IGF-1 as potential disease modifiers in the development and progression of NAFLD.

Relationship between adiponectin and intramuscular fat content determined by ultrasonography in older adults

Age-associated intramuscular adipose tissue (IntraMAT) deposition induces the development of insulin resistance and metabolic syndrome. However, the relationship between IntraMAT and biochemical parameters in older adults remains unclear. The purpose of this study, therefore, was to elucidate the relationship between adiponectin and echo intensity–estimated IntraMAT using ultrasonography in normal-weight older adults (men 9, women 13) and examine biochemical parameters. Blood tests were performed to determine fasting levels of glucose, insulin, hemoglobin A1c, total cholesterol (Total-C), high-density-lipoprotein cholesterol, low-density-lipoprotein cholesterol (LDL-C), free fatty acid, triglycerides (TGs), adiponectin, leptin, high-sensitivity C-reactive protein, and high-sensitivity tumor necrosis factor, and homoeostasis model assessment index of insulin resistance (HOMA-IR). Mean gray-scale echo intensity was calculated as the IntraMAT index of the vastus lateralis. Waist circumference was measured at the level of the navel as the visceral adipose tissue (VAT) index. Echo intensity was significantly inversely correlated with adiponectin or LDL-C, and that was significantly positively correlated with TG. Adiponectin level was inversely correlated with waist circumference. Partial correlation analysis with waist circumference as the control variable revealed that adiponectin was inversely correlated with echo intensity, independent of waist circumference, whereas no such correlation was observed after controlling for LDL-C and TG levels. When biochemical parameters were grouped in the principal component analysis, among men, Total-C, insulin, and HOMA-IR or hemoglobin A1c, and high-sensitivity tumor necrosis factor–alpha were grouped with the same distribution for factors 1 and 2. Among women, glucose, insulin, HOMA-IR, and Total-C or TGs were grouped with the same distribution for factors 1 and 2. These data suggest that adiponectin level is related to IntraMAT content, independent of VAT in normal-weight older adults. The dynamics of adiponectin might not be similar to those of other circulating biochemical parameters in older men and women.

Association between muscle mass and insulin sensitivity independent of detrimental adipose depots in young adults with overweight/obesity

BACKGROUND/OBJECTIVE

Less muscle mass has been associated with greater insulin resistance, but whether the association is independent of deleterious adipose depots in young adults with overweight/obesity who are at high risk for type 2 diabetes (T2DM) but are otherwise metabolically healthy is not known. The objective of this study was to determine whether muscle mass is independently associated with insulin sensitivity (IS) in young adults with overweight/obesity.

SUBJECTS/METHODS

Cross-sectional Clinical Research Center study of 132 adults, 21-45yo, BMI ≥ 25 kg/m² and metabolically healthy without T2DM. Primary independent variable: percent ideal appendicular lean mass (ALM) calculated as measured ALM divided by predicted ALM for age, weight, and height, calculated using validated NHANES data-based equation. Primary dependent variable: IS by Matsuda index.

RESULTS

Mean age was 34.3 ± 6.8 years, and mean BMI 35.8 ± 5.8 kg/m² (mean ± SD). Individuals in the highest % ideal ALM tertile had mean IS 45% higher than the lowest tertile [6.94 ± 0.85 vs 4.80 ± 0.56 (mean ± SEM), p = 0.008] (sex interaction p = 0.003). Men in the highest % ideal ALM tertile had mean IS twice the lowest tertile (5.47 ± 0.68 vs 2.68 ± 0.34, p = 0.001), which remained significant controlling for visceral/subcutaneous and intermuscular adipose tissue, and intramyocellular and intrahepatic lipids (p = 0.03). The association was not significant in women.

CONCLUSIONS

Muscle mass is associated with IS independent of detrimental adipose depots in young men with overweight/obesity, at risk for T2DM but currently metabolically healthy. Muscle mass relative to sex, age, weight, and height-specific norms may be used to ascertain individual T2DM risk associated with low muscle mass.

Blood level of adiponectin is positively associated with lean mass in women without type 2 diabetes

OBJECTIVE

The objective of this study was to evaluate the relationship between blood levels of adiponectin and leptin with lean body and trunk adipose mass in women with and without type 2 diabetes mellitus (T2DM).

METHODS

This cross-sectional study analyzed baseline data from five previous clinical studies involving postmenopausal women (n = 95). Body composition was assessed by dual-energy x-ray absorptiometry, and appendicular lean mass was calculated based on body mass index (ALMBMI). Adipokines and cytokines were measured by enzyme-linked immunosorbent assay. Linear mixed-effect models with a random study effect were used to investigate the relationship between predictors (eg, adiponectin, leptin), outcomes (eg, ALMBMI, trunk adipose mass), and co-variables (T2DM status, age, interleukin-6, and C-reactive protein).

RESULTS

Postmenopausal women with T2DM had lower ALMBMI than those without T2DM. There was a positive association between blood adiponectin and ALMBMI in postmenopausal women without T2DM, but no association in those with T2DM. Blood leptin was negatively associated with ALMBMI for women regardless of T2DM diagnosis. Blood adiponectin was negatively associated, whereas blood leptin was positively associated with trunk adipose mass for the entire cohort.

CONCLUSIONS

T2DM status moderated the relationship between blood adiponectin and ALMBMI, where blood adiponectin was positively associated with ALMBMI in postmenopausal women without T2DM, but not those with T2DM. Dysregulated metabolism in T2DM may contribute to lower muscle mass in women with T2DM, but future research is required to elucidate this mechanistic link. The negative association between blood leptin and ALMBMI was a novel finding. Future studies will need to more clearly define the relationship between these variables.

Sex differences in body composition and association with cardiometabolic risk

Background

Body composition differs between men and women, with women having proportionally more fat mass and men more muscle mass. Although men and women are both susceptible to obesity, health consequences differ between the sexes. The purpose of our study was to assess sex differences in body composition using anatomic and functional imaging techniques, and its relationship to cardiometabolic risk markers in subjects with overweight/obesity.

Methods

After written informed consent, we prospectively recruited 208 subjects with overweight/obesity who were otherwise healthy (94 men, 114 women, age 37 ± 10 years, BMI 35 ± 6 kg/m²). Subjects underwent dual-energy X-ray absorptiometry (DXA) and computed tomography (CT) for fat and muscle mass, proton MR spectroscopy (1H-MRS) for intrahepatic (IHL) and intramyocellular lipids (IMCL), an oral glucose tolerance test, serum insulin, lipids, and inflammatory markers. Men and women were compared by Wilcoxon signed rank test. Linear correlation and multivariate analyses between body composition and cardiometabolic risk markers were performed.

Results

Women and men were of similar mean age and BMI (p ≥ 0.2). Women had higher %fat mass, extremity fat, and lower lean mass compared to men (p ≤ 0.0005). However, men had higher visceral adipose tissue (VAT) and IMCL and higher age-and BMI-adjusted IHL (p < 0.05). At similar age and BMI, men had a more detrimental cardiometabolic risk profile compared to women (p < 0.01). However, VAT in women, and IMCL in men, were more strongly associated with cardiometabolic risk markers, while more lower extremity fat was associated with a more favorable cardiometabolic profile in women compared to men (p ≤ 0.03).

Conclusions

Although the male pattern of fat distribution is associated with a more detrimental cardiometabolic risk profile compared to women of similar age and BMI, VAT is more strongly associated with cardiometabolic risk markers in women, while IMCL are more detrimental in men. Lower extremity fat is relatively protective, in women more than in men. This suggests that detailed anatomic and functional imaging, rather than BMI, provides a more complete understanding of metabolic risk associated with sex differences in fat distribution.

Chicken Is a Useful Model to Investigate the Role of Adipokines in Metabolic and Reproductive Diseases

Reproduction is a complex and essential physiological process required by all species to produce a new generation. This process involves strict hormonal regulation, depending on a connection between the hypothalamus-pituitary-gonadal axis and peripheral organs. Metabolic homeostasis influences the reproductive functions, and its alteration leads to disturbances in the reproductive functions of humans as well as animals. For a long time, adipose tissue has been recognised as an endocrine organ but its ability to secrete and release hormones called adipokines is now emerging. Adipokines have been found to play a major role in the regulation of metabolic and reproductive processes at both central and peripheral levels. Leptin was initially the first adipokine that has been described to be the most involved in the metabolism/reproduction interrelation in mammals. In avian species, the role of leptin is still under debate. Recently, three novel adipokines have been discovered: adiponectin (ADIPOQ, ACRP30), visfatin (NAMPT, PBEF), and chemerin (RARRES2, TIG2). However, their mode of action between mammalian and nonmammalian species is different due to the different reproductive and metabolic systems. Herein, we will provide an overview of the structure and function related to metabolic and reproductive mechanisms of the latter three adipokines with emphasis on avian species.

Body and liver fat content and adipokines in schizophrenia: a magnetic resonance imaging and spectroscopy study

RATIONALE

Although antipsychotic treatment often causes weight gain and lipid abnormalities, quantitative analyses of tissue-specific body fat content and its distribution along with adipokines have not been reported for antipsychotic-treated patients.

OBJECTIVES

The purposes of the present study were to quantitatively assess abdominal and liver fat in patients with schizophrenia on antipsychotic treatment and age- and body mass index (BMI)-matched healthy controls and to evaluate their associations with plasma leptin and adiponectin levels.

METHODS

In 13 schizophrenia patients on antipsychotic treatment and 11 age- and BMI-matched controls, we simultaneously quantified visceral and subcutaneous fat content using T1-weighted magnetic resonance imaging and liver fat content by ¹H magnetic resonance spectroscopy. Associations of tissue-specific fat content with plasma levels of leptin and adiponectin were evaluated.

RESULTS

Plasma adiponectin level (μg/mL) was not statistically different between groups (7.02 ± 2.67 vs. 7.59 ± 2.92), whereas plasma leptin level (ng/mL) trended to be higher in patients than in controls (11.82 ± 7.89 vs. 7.93 ± 5.25). The values of liver fat (%), visceral fat (L), and subcutaneous fat (L) were 9.64 ± 8.03 vs. 7.07 ± 7.35, 4.41 ± 1.64 vs. 3.31 ± 1.97, and 8.37 ± 3.34 vs. 7.16 ± 2.99 in patients vs. controls, respectively. Liver fat content was inversely correlated with adiponectin in controls (r =  - 0.87, p < 0.001) but not in patients (r =  - 0.26, p = 0.39). In both groups, visceral fat was inversely associated with adiponectin (controls : r =  - 0.66, p = 0.03; patients : r =  - 0.65, p = 0.02), while subcutaneous fat was positively correlated with leptin (controls : r = 0.90, p < 0.001; patients : r = 0.67, p = 0.01).

CONCLUSIONS

These findings suggest that antipsychotic treatment may disrupt the physiological relationship between liver fat content and adiponectin but does not essentially affect the associations of adiponectin and leptin with visceral and subcutaneous compartments.

Short- and Long-Term Reproducibility of Intrahepatic Lipid Quantification by 1H-MR Spectroscopy and CT in Obesity

OBJECTIVE

This study aimed to assess short- and long-term reproducibility of intrahepatic lipid (IHL) quantification by proton magnetic resonance spectroscopy (H-MRS) and computed tomography (CT).

METHODS

Sixteen obese subjects underwent H-MRS using a single-voxel point-resolved single-voxel spectroscopy sequence at 3 T and noncontrast single-slice CT of the liver. Measurements were repeated after 6 weeks and 6 months. Clinical parameters (weight, activity, serum lipids) were collected. Short-term (baseline to 6 weeks) and long-term (baseline to 6 months) reproducibility of IHL was assessed by coefficient of variance (CV), SD, and intraclass correlation coefficient (ICC).

RESULTS

Short-term reproducibility and long-term reproducibility of H-MRS were as follows: CV, 5.9% to 18.8%; SD, 0.7 to 1.9; and ICC, 0.998 to 0.995 (95% confidence interval, 0.942-0.999). Short-term reproducibility and long-term reproducibility of CT were as follows: CV, 4.4% to 14.2%; SD, 2.4 to 8.7; and ICC, 0.766 to 0.982 (95% confidence interval, 0.271-0.994). There was no significant change in clinical parameters (P > 0.3).

CONCLUSIONS

Proton magnetic resonance spectroscopy and CT are reproducible methods for short- and long-term quantification of IHL content. Our results can guide sample size calculations for interventional and longitudinal studies.

Abdominal adipose tissue in MGUS and multiple myeloma

OBJECTIVE

To determine abdominal adipose tissue parameters on PET/CT in patients with monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) that may serve as predictors of progression of MGUS to MM. We hypothesized that patients with MM had higher abdominal adiposity and higher fat metabolic activity compared to patients with MGUS.

MATERIALS AND METHODS

Our retrospective study was IRB approved and HIPAA compliant. The study group comprised 40 patients (mean age 64 ± 13 years) with MGUS and 32 patients (mean age 62 ± 10 years) with recently diagnosed MM (mean time since diagnosis of MM 3.0 ± 3.9 months) who had not undergone MM treatment. All patients underwent whole body FDG-PET/CT. Total abdominal adipose tissue (TAT), abdominal subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) cross sectional areas (CSA) (cm(2)) and metabolic activity (SUV) were assessed. Groups were compared using ANOVA. ROC curve analysis was performed to determine cutoff values for abdominal adipose tissue parameters to detect MM.

RESULTS

Patients with recently diagnosed MM had higher TAT and SAT CSA (p ≤ 0.03) and higher fat metabolic activity (p < 0.01). VAT metabolic activity showed the highest sensitivity and specificity for identifying patients with MM (area under the curve 0.95 with cutoff value of >0.34, sensitivity 90.6 %, specificity 92.5 %, p < 0.0001).

CONCLUSIONS

Patients who were recently diagnosed with MM had higher abdominal fat CSA and higher fat metabolic activity compared to patients with MGUS. These parameters may serve as novel biomarkers of progression of MGUS to MM.

Marrow fat composition in anorexia nervosa

PURPOSE

Women with anorexia nervosa (AN) have increased marrow fat despite severe depletion of body fat. Recent studies have suggested that marrow fat composition may serve as a biomarker for bone quality. The purpose of our study was to investigate marrow fat composition of the femur using proton MR spectroscopy ((1)H MRS), and the relationship between measures of marrow fat composition and BMD and body composition in women with AN and normal-weight controls.

MATERIALS AND METHODS

14 women with AN (29.5±1.9years) and 12 age-matched normal-weight controls underwent (1)H MRS to determine total marrow fat content and marrow fat composition of the femoral diaphysis and soleus intramyocellular lipids und unsaturated muscle lipids. MRI was performed to quantify abdominal fat, thigh fat and muscle areas. Lumbar spine BMD, fat and lean mass were assessed by DXA.

RESULTS

Subjects with AN had higher marrow fat content (p<0.05), but similar marrow fat composition (p>0.05) compared to normal-weight controls. There was an inverse association between marrow methylene protons, an estimate of fatty acid (FA) saturated bonds, and lumbar spine BMD (r=-0.52, p=0.008) independent of %ideal body weight (%IBW). Olefinic protons at 5.3ppm, an estimate of FA unsaturated bonds, were inversely associated with body fat depots, independent of %IBW, and positively associated with soleus unsaturation (p≤0.05).

CONCLUSION

Women with AN have higher total femoral marrow fat but similar composition compared to normal-weight controls. The degree of marrow FA saturation correlates inversely with BMD, suggesting that saturated lipids may have negative effects on BMD. The degree of marrow FA unsaturation correlates positively with soleus unsaturation, suggesting that marrow fat composition may be influenced by the same factors as ectopic lipid composition in muscle.

Adiponectin isoforms differentially affect gene expression and the lipidome of primary human hepatocytes

Adiponectin (APN) exerts multiple beneficial effects in obesity and protects from liver injury. Different APN isoforms circulate in serum, and here, the effect of low molecular weight (LMW) and higher molecular weight (HMW) APN on primary human hepatocytes (PHH) has been analyzed. APN is not detected in hepatocyte lysates; levels are strongly increased by HMW-APN, but not by LMW-APN, suggesting the distinct uptake/degradation of APN isoforms by PHH. Several genes with a role in fibrosis, glucose and lipid metabolism known to be regulated by HMW-APN are not affected by the LMW-isoform. Follistatin is reduced by HMW-APN and induced by LMW-APN in supernatants of PHH. Fibroblast growth factor 21 is repressed by both isoforms. Cellular triglycerides and cholesterol levels are not reduced by APN. Total phospholipids, including plasmalogens and sphingomyelins, are not changed upon APN incubation, while distinct species are either induced or repressed. Unexpectedly, total ceramide is increased by LMW-APN. Current data show that APN isoforms differentially affect hepatocyte gene expression, but do not grossly alter the hepatocyte lipidome.

Effects of growth hormone administration for 6 months on bone turnover and bone marrow fat in obese premenopausal women

PURPOSE

Abdominal adiposity is associated with low BMD and decreased growth hormone (GH) secretion, an important regulator of bone homeostasis. The purpose of our study was to determine the effects of a short course of GH on markers of bone turnover and bone marrow fat in premenopausal women with abdominal adiposity.

MATERIALS AND METHODS

In a 6-month, randomized, double-blind, placebo-controlled trial we studied 79 abdominally obese premenopausal women (21-45 y) who underwent daily sc injections of GH vs. placebo. Main outcome measures were body composition by DXA and CT, bone marrow fat by proton MR spectroscopy, P1NP, CTX, 25(OH)D, hsCRP, undercarboxylated osteocalcin (ucOC), preadipocyte factor 1 (Pref 1), apolipoprotein B (ApoB), and IGF-1.

RESULTS

GH increased IGF-1, P1NP, 25(OH)D, ucOC, bone marrow fat and lean mass, and decreased abdominal fat, hsCRP, and ApoB compared with placebo (p<0.05). There was a trend toward an increase in CTX and Pref-1. Among all participants, a 6-month increase in IGF-1 correlated with 6-month increase in P1NP (p=0.0005), suggesting that subjects with the greatest increases in IGF-1 experienced the greatest increases in bone formation. A six-month decrease in abdominal fat, hsCRP, and ApoB inversely predicted 6-month change in P1NP, and 6-month increase in lean mass and 25(OH)D positively predicted 6-month change in P1NP (p≤0.05), suggesting that subjects with greatest decreases in abdominal fat, inflammation and ApoB, and the greatest increases in lean mass and 25(OH)D experienced the greatest increases in bone formation. A six-month increase in bone marrow fat correlated with 6-month increase in P1NP (trend), suggesting that subjects with the greatest increases in bone formation experienced the greatest increases in bone marrow fat. Forward stepwise regression analysis indicated that increase in lean mass and decrease in abdominal fat were positive predictors of P1NP. When IGF-1 was added to the model, it became the only predictor of P1NP.

CONCLUSION

GH replacement in abdominally obese premenopausal women for 6 months increased bone turnover and bone marrow fat. Reductions in abdominal fat, and inflammation, and increases in IGF-1, lean mass and vitamin D were associated with increased bone formation. The increase in bone marrow fat may reflect changes in energy demand from increased bone turnover.

Adiponectin action in skeletal muscle

The beneficial metabolic effects of adiponectin which confer insulin-sensitizing and anti-diabetic effects are well established. Skeletal muscle is an important target tissue for adiponectin where it regulates glucose and fatty acid metabolism directly and via insulin sensitizing effects. Cell surface receptors and the intracellular signaling events via which adiponectin orchestrates metabolism are now becoming well characterized. The initially accepted dogma of adiponectin action was that the physiological effects were mediated via endocrine effects of adipose-derived adiponectin. However, in recent years it has been established that skeletal muscle can also produce and secrete adiponectin that can elicit important functional effects. There is evidence that skeletal muscle adiponectin resistance may develop in obesity and play a role in the pathogenesis of diabetes. In summary, adiponectin acting in an autocrine and endocrine manner has important metabolic and insulin sensitizing effects on skeletal muscle which contribute to the overall anti-diabetic outcome of adiponectin action.

Assessment of abdominal fat compartments using DXA in premenopausal women from anorexia nervosa to morbid obesity

OBJECTIVE

To test a newly developed dual energy X-ray absorptiometry (DXA) method for abdominal fat depot quantification in subjects with anorexia nervosa (AN), normal weight, and obesity using CT as a gold standard.

DESIGN AND METHODS

135 premenopausal women (overweight/obese: n = 89, normal-weight: n = 27, AN: n = 19); abdominal visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and total adipose tissue (TAT) areas determined on CT and DXA.

RESULTS

There were strong correlations between DXA and CT measurements of abdominal fat compartments in all groups with the strongest correlation coefficients in the normal-weight and overweight/obese groups. Correlations of DXA and CT VAT measurements were strongest in the obese group and weakest in the AN group. DXA abdominal fat depots were higher in all groups compared to CT, with the largest % mean difference in the AN group and smallest in the obese group.

CONCLUSION

A new DXA technique is able to assess abdominal fat compartments including VAT in premenopausal women across a large weight spectrum. However, DXA measurements of abdominal fat were higher than CT, and this percent bias was most pronounced in the AN subjects and decreased with increasing weight, suggesting that this technique may be more useful in obese individuals.

Obesity pharmacotherapy: current perspectives and future directions

The rising tide of obesity and its related disorders is one of the most pressing health concerns worldwide, yet existing medicines to combat the problem are disappointingly limited in number and effectiveness. Recent advances in mechanistic insights into the neuroendocrine regulation of body weight have revealed an expanding list of molecular targets for novel, rationally designed antiobesity pharmaceutical agents. Antiobesity drugs act via any of four mechanisms: 1) decreasing energy intake, 2) increasing energy expenditure or modulating lipid metabolism, 3) modulating fat stores or adipocyte differentiation, and 4) mimicking caloric restriction. Various novel drug candidates and targets directed against obesity are currently being explored. A few of them are also in the later phases of clinical trials. This review discusses the development of novel antiobesity drugs based on current understanding of energy homeostasis

Ectopic and serum lipid levels are positively associated with bone marrow fat in obesity

PURPOSE

To investigate the associations between ectopic and serum lipid levels and bone marrow fat, as a marker of stem cell differentiation, in young obese men and women, with the hypothesis that ectopic and serum lipid levels would be positively associated with bone marrow fat.

MATERIALS AND METHODS

The study was institutional review board approved and complied with HIPAA guidelines. Written informed consent was obtained. The study group comprised 106 healthy young men and women (mean age, 33.7 years ± 6.8 [standard deviation]; range, 19-45 years; mean body mass index (BMI), 33.1 kg/m(2) ± 7.1; range, 18.1-48.8 kg/m(2)) who underwent hydrogen 1((1)H) magnetic resonance (MR) spectroscopy by using a point-resolved spatially localized spectroscopy sequence at 3.0 T of L4 for bone marrow fat content, of soleus muscle for intramyocellular lipids (IMCL), and liver for intrahepatic lipids (IHL), serum cholesterol level, serum triglyceride level, and measures of insulin resistance (IR). Exercise status was assessed with the Paffenbarger activity questionnaire.

RESULTS

There was a positive correlation between bone marrow fat and IHL (r = 0.21, P = .048), IMCL (r = 0.27, P = .02), and serum triglyceride level (r = 0.33, P = .001), independent of BMI, age, IR, and exercise status (P < .05). High-density lipoprotein cholesterol levels were inversely associated with bone marrow fat content, independent of BMI, age, IR, and exercise status (r = -0.21, P = .019).

CONCLUSION

Results of this study suggest that ectopic and serum lipid levels are positively associated with bone marrow fat in obese men and women.

Ectopic and serum lipid levels are positively associated with bone marrow fat in obesity

PURPOSE

To investigate the associations between ectopic and serum lipid levels and bone marrow fat, as a marker of stem cell differentiation, in young obese men and women, with the hypothesis that ectopic and serum lipid levels would be positively associated with bone marrow fat.

MATERIALS AND METHODS

The study was institutional review board approved and complied with HIPAA guidelines. Written informed consent was obtained. The study group comprised 106 healthy young men and women (mean age, 33.7 years ± 6.8 [standard deviation]; range, 19-45 years; mean body mass index (BMI), 33.1 kg/m(2) ± 7.1; range, 18.1-48.8 kg/m(2)) who underwent hydrogen 1((1)H) magnetic resonance (MR) spectroscopy by using a point-resolved spatially localized spectroscopy sequence at 3.0 T of L4 for bone marrow fat content, of soleus muscle for intramyocellular lipids (IMCL), and liver for intrahepatic lipids (IHL), serum cholesterol level, serum triglyceride level, and measures of insulin resistance (IR). Exercise status was assessed with the Paffenbarger activity questionnaire.

RESULTS

There was a positive correlation between bone marrow fat and IHL (r = 0.21, P = .048), IMCL (r = 0.27, P = .02), and serum triglyceride level (r = 0.33, P = .001), independent of BMI, age, IR, and exercise status (P < .05). High-density lipoprotein cholesterol levels were inversely associated with bone marrow fat content, independent of BMI, age, IR, and exercise status (r = -0.21, P = .019).

CONCLUSION

Results of this study suggest that ectopic and serum lipid levels are positively associated with bone marrow fat in obese men and women.

Circulating levels of adipokines and IGF-1 are associated with skeletal muscle strength of young and old healthy subjects

It is known that adipose tissue mass increases with age, and that a number of hormones, collectively called adipokines, are produced by adipose tissue. For most of them it is not known whether their plasmatic levels change with age. Moreover, it is known that adipose tissue infiltration in skeletal muscle is related to sarcopenia and loss of muscle strength. In this study we investigated the age-related changes of representative adipokines and insulin-like growth factor (IGF)-1 and their effect on muscle strength. We studied the association between circulating levels of adiponectin, leptin, resistin and IGF-1 and muscle strength. This cross-sectional study included 412 subjects of different age (152 subjects aged 18-30 years and 260 subjects aged 69-81 years) recruited within the framework of the European research network project "Myoage". The levels of adiponectin (both in male and female subjects) and leptin (only in males) were significantly higher in old subjects compared to young, while those of IGF-1 were lower in old subjects. In old subjects adiponectin, resistin and the resistin/IGF-1 ratio (but not IGF-1 alone) were inversely associated with quadriceps torque, while only adiponectin was inversely associated with handgrip strength independently from percentage of fat mass, height, age, gender and geographical origin. The ratio of leptin to adiponectin was directly associated with handgrip strength in both young and old subjects. These results suggest that in humans the age-associated loss of strength is associated with the levels of representative adipokines and IGF-1.

Simplifying the energy balance message for breast cancer prevention

Simple prevention messages based on understandable biologic principles are likely to be adopted. The long-held premise that postmenopausal obesity elevates, but premenopausal obesity reduces, risk for breast cancer is confusing to the public. Furthermore, decades of positive energy balance may be difficult to suddenly reverse at the time of the menopause. In this issue (beginning on page 583), Cecchini et al. suggest that obesity may also be a risk factor for pre-menopausal women 35 and older who have additional risk factors for breast cancer. Although the relative impact of dysregulated energy metabolism depends on many factors including age, hormonal milieu, and competing risk factors, as well as how it is measured, avoiding weight gain after age 30 is increasingly being recognized as a simple way to reduce risk of breast cancer.