Physiological regulation of NEFA availability: lipolysis pathway

The impact of the administration of red ginseng (Panax ginseng) on lipid metabolism and free fatty acid profiles in healthy horses using a molecular networking approach

This study investigated the potential benefits of the administration of red ginseng (RG) on lipid metabolism and the profiles of individual free fatty acids (FFAs) in healthy horses. Eight healthy horses, raised under similar conditions, were randomly divided into two groups, each comprising four horses. The experimental group received powdered RG (600 mg/kg/day) mixed with a carrier, and the control group received only the carrier. The parameters associated with lipid metabolism and probable adverse effects were evaluated in both groups after 3 weeks. The computational molecular networking (MN) approach was applied to analyze the FFA profiles. The results indicated that RG administration significantly reduced blood triglyceride levels in the experimental group. Analysis of the FFAs using MN revealed significant decreases in specific types of FFAs (C12:0, dodecanoic acid; C14:0, myristric acid; C18:1, oleic acid; C18:2, linoleic acid). RG consumption did not produce significant adverse effects on the renal, hepatic, and immune functions. Thus, RG was found to effectively modulate lipid metabolism and the levels of individual FFAs. The application of the MN for the analysis of FFAs represents a novel approach and can be considered for future research.

No impact of a high-fat meal coupled with intermittent hypoxemia on acute kidney injury biomarkers in adults with and without obstructive sleep apnea

Obstructive sleep apnea (OSA) is characterized by chronic intermittent hypoxemia, which is associated with progressive loss of kidney function, where postprandial fluctuations in renal physiology may further compromise oxygen supply and kidney function. Therefore, we measured biomarkers of acute kidney injury (AKI) following a high-fat meal with and without intermittent hypoxemia. Eighteen healthy young men (mean age [SD]: 22.7 years [3.1]) and seven middle-aged to older individuals with OSA (54.4 years [6.4]) consumed a high-fat meal during normoxia or intermittent hypoxemia (~15 hypoxic cycles per hour, ~85% oxyhemoglobin saturation) for 6 h. We observed no changes in estimated glomerular filtration rate and plasma concentrations of creatinine, neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1) at any measured time points. In both groups, plasma concentrations of interleukin-18 (IL-18) increased after 6 h during normoxia only (p = 0.033, ηp 2  = 0.122), and plasma concentrations of liver-type fatty acid-binding protein (L-FABP) transiently decreased after 3 h in both conditions (p = 0.008, ηp 2  = 0.152). These findings indicate that AKI biomarkers are not acutely elevated during the postprandial state with or without intermittent hypoxemia, suggesting that other mechanisms may play more important roles in the progression of kidney disease in OSA.

Supplemental Clostridium butyricum modulates lipid metabolism by reshaping the gut microbiota composition and bile acid profile in IUGR suckling piglets

BACKGROUND

Intrauterine growth restriction (IUGR) can cause lipid disorders in infants and have long-term adverse effects on their growth and development. Clostridium butyricum (C. butyricum), a kind of emerging probiotics, has been reported to effectively attenuate lipid metabolism dysfunctions. Therefore, the objective of this study was to investigate the effects of C. butyricum supplementation on hepatic lipid disorders in IUGR suckling piglets.

METHODS

Sixteen IUGR and eight normal birth weight (NBW) neonatal male piglets were used in this study. From d 3 to d 24, in addition to drinking milk, the eight NBW piglets (NBW-CON group, n = 8) and eight IUGR piglets (IUGR-CON group, n = 8) were given 10 mL sterile saline once a day, while the remaining IUGR piglets (IUGR-CB group, n = 8) were orally administered C. butyricum at a dose of 2 × 10⁸ colony-forming units (CFU)/kg body weight (suspended in 10 mL sterile saline) at the same frequency.

RESULTS

The IUGR-CON piglets exhibited restricted growth, impaired hepatic morphology, disordered lipid metabolism, increased abundance of opportunistic pathogens and altered ileum and liver bile acid (BA) profiles. However, C. butyricum supplementation reshaped the gut microbiota of the IUGR-CB piglets, characterized by a decreased abundance of opportunistic pathogens in the ileum, including Streptococcus and Enterococcus. The decrease in these bile salt hydrolase (BSH)-producing microbes increased the content of conjugated BAs, which could be transported to the liver and function as signaling molecules to activate liver X receptor α (LXRα) and farnesoid X receptor (FXR). This activation effectively accelerated the synthesis and oxidation of fatty acids and down-regulated the total cholesterol level by decreasing the synthesis and promoting the efflux of cholesterol. As a result, the growth performance and morphological structure of the liver improved in the IUGR piglets.

CONCLUSION

These results indicate that C. butyricum supplementation in IUGR suckling piglets could decrease the abundance of BSH-producing microbes (Streptococcus and Enterococcus). This decrease altered the ileum and liver BA profiles and consequently activated the expression of hepatic LXRα and FXR. The activation of these two signaling molecules could effectively normalize the lipid metabolism and improve the growth performance of IUGR suckling piglets.

Role of bile acid receptor FXR in development and function of brown adipose tissue

Bile acids act as signalling molecules that contribute to maintenance of energy homeostasis in mice and humans. Activation of G-protein-coupled bile acid receptor TGR5 induces energy expenditure in brown adipose tissue (BAT). However, a role for the nuclear bile acid receptor Farnesoid X receptor (FXR) in BAT has remained ambiguous. We aimed to study the potential role of FXR in BAT development and functioning. Here we demonstrate low yet detectable expression of the α1/2 isoforms of FXR in murine BAT that markedly decreases upon cold exposure. Moderate adipose tissue-specific FXR overexpression in mice induces pronounced BAT whitening, presenting with large intracellular lipid droplets and extracellular collagen deposition. Expression of thermogenic marker genes including the target of Tgr5, Dio2, was significantly lower in BAT of chow-fed aP2-hFXR mice compared to wild-type controls. Transcriptomic analysis revealed marked up-regulation of extracellular matrix formation and down-regulation of mitochondrial functions in BAT from aP2-hFXR mice. In addition, markers of cell type lineages deriving from the dermomyotome, such as myocytes, as well as markers of cellular senescence were strongly induced. The response to cold and β3-adrenergic receptor agonism was blunted in these mice, yet resolved BAT whitening. Newborn cholestatic Cyp2c70^-/- mice with a human-like bile acid profile also showed distinct BAT whitening and upregulation of myocyte-specific genes, while thermogenic markers were down-regulated. Ucp1 expression inversely correlated with plasma bile acid levels. Therefore, bile acid signalling via FXR has a role in BAT function already early in tissue development. Functionally, FXR activation appears to oppose TGR5-mediated thermogenesis.

α-Linolenic acid rich-chia seed modulates visceral adipose tissue collagen deposition, lipolytic enzymes expression, insulin signaling and GLUT-4 levels in a diet-induced adiposity rodent model

Given obesity and its associated metabolic disorders have reached epidemic proportions, the study of therapeutic strategies targeting white adipose tissue (WAT) are of main research interest. We previously shown that α-linolenic acid-rich chia seed was able to ameliorate a wide range of metabolic disorders including body fat accretion in sucrose-rich diet (SRD)-fed rats, an experimental model of visceral adiposity and insulin resistance. However, the mechanisms involved are not fully clarified. The aim of this study was to evaluate the effect of chia seed administration upon WAT remodeling and key enzymes that controls lipolysis, insulin signaling (tAKT, pAKT), and GLUT-4 levels in different visceral fat pad depots (epididymal -eWAT- and retroperitoneal -rWAT- adipose tissues) of SRD-fed rats. Results showed that chia seed reduces adipocytes hypertrophy, the increased lipid content and collagen deposition in both WAT. These changes were accompanied by a significant reduction of HSL and ATGL protein levels in eWAT and HSL protein levels in rWAT. Moreover, chia seed restored the altered expression pattern of the pAKT observed in SRD-fed rats, and modulated GLUT-4 levels. Chia seed could be a dietary intervention of great relevance with potential beneficial effects in the management of body fat excess and WAT function.

Probing Insulin Sensitivity with Metabolically Competent Human Stem Cell-Derived White Adipose Tissue Microphysiological Systems

Impaired white adipose tissue (WAT) function has been recognized as a critical early event in obesity-driven disorders, but high buoyancy, fragility, and heterogeneity of primary adipocytes have largely prevented their use in drug discovery efforts highlighting the need for human stem cell-based approaches. Here, human stem cells are utilized to derive metabolically functional 3D adipose tissue (iADIPO) in a microphysiological system (MPS). Surprisingly, previously reported WAT differentiation approaches create insulin resistant WAT ill-suited for type-2 diabetes mellitus drug discovery. Using three independent insulin sensitivity assays, i.e., glucose and fatty acid uptake and suppression of lipolysis, as the functional readouts new differentiation conditions yielding hormonally responsive iADIPO are derived. Through concomitant optimization of an iADIPO-MPS, it is abled to obtain WAT with more unilocular and significantly larger (≈40%) lipid droplets compared to iADIPO in 2D culture, increased insulin responsiveness of glucose uptake (≈2-3 fold), fatty acid uptake (≈3-6 fold), and ≈40% suppressing of stimulated lipolysis giving a dynamic range that is competent to current in vivo and ex vivo models, allowing to identify both insulin sensitizers and desensitizers.

Benzene Exposure Leads to Lipodystrophy and Alters Endocrine Activity In Vivo and In Vitro

Benzene is a ubiquitous pollutant and mainly accumulates in adipose tissue which has important roles in metabolic diseases. The latest studies reported that benzene exposure was associated with many metabolic disorders, while the effect of benzene exposure on adipose tissue remains unclear. We sought to investigate the effect using in vivo and in vitro experiments. Male adult C57BL/6J mice were exposed to benzene at 0, 1, 10 and 100 mg/kg body weight by intragastric gavage for 4 weeks. Mature adipocytes from 3T3-L1 cells were exposed to hydroquinone (HQ) at 0, 1, 5 and 25 μM for 24 hours. Besides the routine hematotoxicity, animal experiments also displayed significant body fat content decrease from 1 mg/kg. Interestingly, the circulating non-esterified fatty acid (NEFA) level increased from the lowest dose (p_trend < 0.05). Subsequent analysis indicated that body fat content decrease may be due to atrophy of white adipose tissue (WAT) upon benzene exposure. The average adipocyte area of WAT decreased significantly even from 1 mg/kg with no significant changes in total number of adipocytes. The percentages of small and large adipocytes in WAT began to significantly increase or decrease from 1 mg/kg (all p < 0.05), respectively. Critical genes involved in lipogenesis and lipolysis were dysregulated, which may account for the disruption of lipid homeostasis. The endocrine function of WAT was also disordered, manifested as significant decrease in adipokine levels, especially the leptin. In vitro cell experiments displayed similar findings in decreased fat content, dysregulated critical lipid metabolism genes, and disturbed endocrine function of adipocytes after HQ treatment. Pearson correlation analysis showed positive correlations between white blood cell (WBC) count with WAT fat content and plasma leptin level (r = 0.330, 0.344, both p < 0.05). This study shed light on the novel aspect that benzene exposure could induce lipodystrophy and disturb endocrine function of WAT, and the altered physiology of WAT might in turn affect benzene-induced hematotoxicity and metabolic disorders. The study provided new insight into understanding benzene-induced toxicity and the relationship between benzene and adipose tissue.

Association of Serum Nonesterified Fatty Acids with Cardiovascular Event in Patients with Chronic Kidney Disease

Background

Chronic kidney disease (CKD) has been suggested to be associated with a high risk of cardiovascular diseases (CVD). The study aimed to evaluate the prognostic significance of nonesterified fatty acid (NEFA), also well known as free fatty acid, on predicting cardiovascular events in patients with CKD.

Methods

A total of 957 hospitalized patients with CKD in a stable clinical condition were enrolled at baseline. Then, the serum NEFA levels were measured. These included patients were prospectively followed up for a median of 10.2 years (range=0.4–11.5 years). We assessed whether serum NEFA levels at baseline can predict cardiovascular event during the follow-up.

Results

A total of 278 (29.1%) patients experienced cardiovascular events during follow-up. The Kaplan–Meier curve demonstrated that patients with higher serum NEFA levels (≥19.8 mg/dl) had a higher rate of cardiovascular events than patients with lower NEFA levels (<19.8 mg/dl). Multivariate Cox regression analysis suggested that elevated serum NEFA levels (HR=1.62; 95% CI 1.40–2.16, P<0.001) were independently associated with increased risk of cardiovascular events after correction for clinical confounding factors.

Conclusion

Elevated serum NEFA levels were associated with higher risk of cardiovascular events and may be a new parameter predicting cardiovascular events in patients with CKD, which may strengthen its potential effect in clinical practice.

Free Fatty Acid is a Promising Biomarker in Triage Screening for Patients with Colorectal Cancer: A Case-Control Study

Purpose

The aim of our study was to identify the diagnostic ability of free fatty acids (FFAs) in younger colorectal cancer (CRC) patients by comparing carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9).

Methods

Patients screened for CRC at Fujian Medical University Union Hospital from January 2011 to December 2014 were recruited. Patients pathologically diagnosed with CRC or colorectal adenoma (CA) and healthy control participants were included. The enzyme endpoint method was applied to measure FFA levels. Receiver operating characteristic (ROC) curve analysis was performed to further evaluate the diagnostic ability of FFAs.

Results

FFA levels in late-stage patients (tumour-node-metastasis (TNM) stages III-IV) were higher than those in early-stage patients (TNM stages I-II) (P=0.02). The FFA levels in CRC patients were higher than those in controls of all ages, those younger than 50 years, males and females (P<0.001), and this difference was larger for patients younger than 50 years and females than for the all ages group. There was no significant difference in the FFA level between CA patients and healthy participants (P=0.53). The area under the curve (AUC) values of FFA, CEA, CA19-9, FFA+CEA, FFA+CA19-9 and FFA+CEA+CA19-9 distinguished CRC patients from controls at all ages, with values of 0.604, 0.731, 0.640, 0.754, 0.678 and 0.758, respectively; however, in the younger CRC patients (age≤50), the AUC values were 0.701, 0.735, 0.669, 0.798, 0.749, and 0.801. The AUC in female patients younger than 50 years was larger than that in males (0.769 vs 0.660), and this value was greater than the value for CEA in males (0.739) and females (0.729).

Conclusion

The FFA level not only can complement the predictive ability of the CEA and CA19-9 levels but also has a superior predictive ability in female and younger patients with CRC. FFA levels may have a potential role in triage screening of early CRC.

Dietary-challenged mice with Alzheimer-like pathology show increased energy expenditure and reduced adipocyte hypertrophy and steatosis

Alzheimer’s disease (AD) is frequently accompanied by progressing weight loss, correlating with mortality. Counter-intuitively, weight loss in old age might predict AD onset but obesity in midlife increases AD risk. Furthermore, AD is associated with diabetes-like alterations in glucose metabolism. Here, we investigated metabolic features of amyloid precursor protein overexpressing APP23 female mice modeling AD upon long-term challenge with high-sucrose (HSD) or high-fat diet (HFD). Compared to wild type littermates (WT), APP23 females were less prone to mild HSD-induced and considerable HFD-induced glucose tolerance deterioration, despite unaltered glucose tolerance during normal-control diet. Indirect calorimetry revealed increased energy expenditure and hyperactivity in APP23 females. Dietary interventions, especially HFD, had weaker effects on lean and fat mass gain, steatosis and adipocyte hypertrophy of APP23 than WT mice, as shown by ¹H-magnetic-resonance-spectroscopy, histological and biochemical analyses. Proteome analysis revealed differentially regulated expression of mitochondrial proteins in APP23 livers and brains. In conclusion, hyperactivity, increased metabolic rate, and global mitochondrial dysfunction potentially add up to the development of AD-related body weight changes in APP23 females, becoming especially evident during diet-induced metabolic challenge. These findings emphasize the importance of translating this metabolic phenotyping into human research to decode the metabolic component in AD pathogenesis.

Circulating Non-Esterified Fatty Acids as Biomarkers for Fat Content and Composition in Pigs

Simple Summary

Circulating non-esterified fatty acids (NEFA) may be valuable as biomarkers for intramuscular fat content and fatty acid composition, as well as for other meat quality traits, in finishing heavy Duroc pigs. However, circulating NEFA composition may be affected by other factors such as age, fasting duration, and genetic variants related with adipogenesis and fatty acid metabolism pathways (e.g., SCD and LEPR). This study revealed that the circulating NEFA composition, especially the oleic acid content, reflects the metabolic status of an animal at a given time but has limited value as biomarker of intramuscular fat content and fatty acid composition.

Abstract

Circulating non-esterified fatty acids (NEFA) can reflect the composition of dietary fat or adipose tissues depending on the fasting conditions. Therefore, circulating NEFA may be valuable as biomarkers for meat quality traits, such as intramuscular fat content and fatty acid composition in finishing pigs. Genetic variants that regulate lipid metabolism can also modulate the circulating NEFA. We conducted an experiment with 150 heavy Duroc pigs to evaluate fluctuations in the circulating NEFA composition due to age, fasting duration and two genetic polymorphisms, one in the leptin receptor (LEPR; rs709596309) and one in the stearoyl-CoA desaturase (SCD; rs80912566) gene. Circulating NEFA were more saturated and less monounsaturated than the subcutaneous and intramuscular adipose tissues. Absolute circulating NEFA content was more influenced by fasting duration than age. The SCD polymorphism did not impact NEFA content or composition. The LEPR polymorphism affected the content but not the fatty acid composition. Circulating oleic acid NEFA content after a short fasting was positively correlated with intramuscular fat content and, after a long fasting, with intramuscular oleic acid content. We conclude that circulating NEFA reflect environmental and genetic metabolic changes but are of limited value as biomarkers for intramuscular fat content and fatty acid composition.

Effect of short-chain chlorinated paraffins on metabolic profiling of male SD rats

The toxic effect of high-dose of short-chain chlorinated paraffins (SCCPs) has been extensively studied, however the possible health risks induced by SCCPs at low-dose remain largely unknown. In this study, a comprehensive toxicology analysis of SCCPs was conducted with the exposure levels from the environmental dose to the Lowest Observed Adverse Effect Level (LOAEL) of 100 mg/kg/day. General toxicology analysis revealed inconspicuous toxicity of the environmental dose of SCCPs, high dose SCCP exposure inhibited the growth rate and increased the liver weight of rat. Metabolomics analysis indicated that SCCP-induced toxicity was triggered at environmentally relevant doses. First, inhibition of energy metabolism was observed with the decrease in blood glucose and the dysfunction of TCA cycle, which may have contributed to lower body weight gain in rats exposed to a high dose of SCCPs. Second, the increase of free fatty acids indicated the acceleration of lipid metabolism to compensate for the energy deficiency caused by hypoglycemia. Lipid oxidative metabolism inevitably leads to oxidative stress and stimulates the up-regulation of antioxidant metabolites such as GSH and GSSH. The up-regulation of polyunsaturated fatty acids (PUFAs) and phospholipids composed of arachidonic acid indicates the occurrence of inflammation. Dysfunction of lipid metabolism can be an indicator of SCCP-induced liver injury.

Regulatory Roles of SREBF1 and SREBF2 in Lipid Metabolism and Deposition in Two Chinese Representative Fat-Tailed Sheep Breeds

Simple Summary

Sterol regulatory element binding proteins (SREBPs) play the crucial role in regulating the cholesterol and fatty acid metabolism. However, it is unclear whether SREBPs are involved in the regulation of lipid metabolism in fat-tailed sheep. This study reveals the expression profiles of SREBF1 and SREBF2 in liver and adipose tissues of two Chinese representative fat-tailed sheep breeds, and provides a new insight for the regulatory role of SREBP1 and SREBP2 in fat metabolism and deposition in fat-tailed sheep.

Abstract

Sterol regulatory element binding proteins (SREBPs) can regulate the lipid homeostasis by regulating its target genes, which are crucial for the cholesterol and fatty acid metabolism. However, the transcriptional regulation role of SREBPs in fat-tailed sheep is unclear. In this study, two Chinese representative breeds of total 80 fat-tailed sheep were employed, serum triglyceride, total cholesterol (TC), non-esterified fatty acid (NEFA), high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and mRNA expressions of SREBF1 and SREBF2 in seven different adipose tissues and liver were examined in sheep at the ages of 4, 6, 8, 10, and 12 months, respectively. The subcellular localization and function of SREBP1/2 were predicted through bioinformatics approaches. The results demonstrated that serum TC and NEFA levels among breeds were significantly different, and most serum indices were dynamically altered in an age-dependent manner. The mRNA expression profiling of SREBF1 and SREBF2 are breed-specific with temporal and spatial expressions differences. Further analysis shows that SREBF1/2 transcriptional levels and tail traits are closely related. All investigations simplify that SREBF1/2 play a crucial role in lipid metabolism and deposition during growth and development of the fat-tailed sheep, which also provides a novel insight for revealing the genetic mechanism of different tail type and meat quality.

Free fatty acids, cardiovascular disease, and mortality in the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Fasting free fatty acid (FFA) levels may be associated with cardiovascular disease (CVD) and mortality, but research among generally healthy adults, females, and racially/ethnically diverse populations is lacking.

OBJECTIVE

The primary aim of this project was to investigate prospective associations between fasting FFAs and coronary heart disease (CHD) and CVD incidence and CVD-specific and all-cause mortality in a generally healthy age, sex, and racially/ethnically heterogeneous population.

METHODS

This study was conducted in the Multi-Ethnic Study of Atherosclerosis cohort using baseline (2000-2002) fasting FFAs and outcome data through 2015 (N = 6678). Cox proportional hazards regression was used to calculate hazard ratios for associations between FFAs and CHD, CVD, CVD-specific mortality, and all-cause mortality. Interactions by age, sex, race/ethnicity, and metabolic syndrome were evaluated by stratification and cross-product terms. A secondary analysis was conducted to evaluate associations between FFAs, and inflammatory and endothelial activation biomarkers were evaluated using linear regression (analytic N range: 964-6662).

RESULTS

FFA levels were not associated with CHD or CVD incidence. Higher FFAs were associated with CVD-specific and all-cause mortality, but associations were attenuated in fully adjusted models with a borderline significant association remaining only for all-cause mortality (fully adjusted, per standard deviation increase hazard ratio = 1.07, 95% confidence interval: 1.00-1.14). Associations did not differ by age, sex, race/ethnicity, or metabolic syndrome.

CONCLUSIONS

Fasting FFAs were not associated with CHD, CVD, or CVD-specific mortality and were modestly associated with all-cause mortality, regardless of age, sex, race/ethnicity, or metabolic syndrome status.

Impaired Metabolic Flexibility to High-Fat Overfeeding Predicts Future Weight Gain in Healthy Adults

The ability to switch fuels for oxidation in response to changes in macronutrient composition of diet (metabolic flexibility) may be informative of individuals' susceptibility to weight gain. Seventy-nine healthy, weight-stable participants underwent 24-h assessments of energy expenditure and respiratory quotient (RQ) in a whole-room calorimeter during energy balance (EBL) (50% carbohydrate, 30% fat) and then during 24-h fasting and three 200% overfeeding diets in a crossover design. Metabolic flexibility was defined as the change in 24-h RQ from EBL during fasting and standard overfeeding (STOF) (50% carbohydrate, 30% fat), high-fat overfeeding (HFOF) (60% fat, 20% carbohydrate), and high-carbohydrate overfeeding (HCOF) (75% carbohydrate, 5% fat) diets. Free-living weight change was assessed after 6 and 12 months. Compared with EBL, RQ decreased on average by 9% during fasting and by 4% during HFOF but increased by 4% during STOF and by 8% during HCOF. A smaller decrease in RQ, reflecting a smaller increase in lipid oxidation rate, during HFOF but not during the other diets predicted greater weight gain at both 6 and 12 months. An impaired metabolic flexibility to acute HFOF can identify individuals prone to weight gain, indicating that an individual's capacity to oxidize dietary fat is a metabolic determinant of weight change.

A high serum-free fatty acid level is associated with cancer

PURPOSE

The objectives of this work were to investigate whether the serum-free fatty acid (FFA) level is meaningful in cancer patients and its role in cancer diagnosis.

METHODS

A total of 2206 patients were divided into a cancer group (n = 1019) and a noncancer group (n = 1187). Age, sex, body mass index (BMI), and serum FFA and serum albumin levels were collected. Cancer patients were divided into subgroups according to the location of the cancer. We then compared serum FFA levels among the tumor subgroups. A receiver operating characteristic (ROC) curve analysis was performed to further evaluate the diagnostic ability of the FFA level. SPSS 22.0 software was used to analyze the results.

RESULTS

The FFA level was higher in the cancer group than in the noncancer group. According to the multivariate analysis, there was also an increased risk of cancer associated with a high FFA level after adjusting for old age, female sex, and a low BMI. In the subgroup analysis, the FFA level in patients with lung cancer, gastric cancer, thyroid cancer, rectal cancer, colon cancer, and ovarian cancer was significantly higher than that in noncancer patients. The area under the effect-time curve (AUC) of FFAs in the whole cancer group was 0.58, while the thyroid cancer, rectal cancer, and ovarian cancer subgroups had AUCs > 0.6.

CONCLUSION

Our study provides clinical evidence to support that fatty acid metabolism is associated with cancers and demonstrates that a high FFA level in the serum may be an indicator of cancer.

The role of pro-inflammatory cytokines in lipid metabolism of metabolic diseases

Adipose tissue has been considered as a crucial source of certain pro-inflammatory cytokines; conversely, these pro-inflammatory cytokines are involved in regulating the proliferation and apoptosis of adipocytes, promoting lipolysis, inhibiting lipid synthesis and decreasing blood lipids, etc. In recent decades, extensive studies have indicated that pro-inflammatory cytokines play important roles in the development of lipid metabolism of metabolic diseases, including obesity, atherosclerosis, steatohepatitis and hyperlipoproteinemia. However, the involved pro-inflammatory cytokines types and the underlying mechanisms remain largely unknown. The "re-discovery" of cancer as a metabolic disorder largely occurred in the last five years. Although pro-inflammatory cytokines have been intensively investigated in cancer research, there are very few studies about the roles of pro-inflammatory cytokines in the lipid metabolism of cancer. In the current review, we provide an overview of the progress that has been made in the roles of different pro-inflammatory cytokines in lipid metabolism of metabolic diseases including cancer.

Adipogenesis: A Necessary but Harmful Strategy

Obesity is considered to significantly increase the risk of the development of a vast range of metabolic diseases. However, adipogenesis is a complex physiological process, necessary to sequester lipids effectively to avoid lipotoxicity in other tissues, like the liver, heart, muscle, essential for maintaining metabolic homeostasis and has a crucial role as a component of the innate immune system, far beyond than only being an inert mass of energy storage. In pathophysiological conditions, adipogenesis promotes a pro-inflammatory state, angiogenesis and the release of adipokines, which become dangerous to health. It results in a hypoxic state, causing oxidative stress and the synthesis and release of harmful free fatty acids. In this review, we try to explain the mechanisms occurring at the breaking point, at which adipogenesis leads to an uncontrolled lipotoxicity. This review highlights the types of adipose tissue and their functions, their way of storing lipids until a critical point, which is associated with hypoxia, inflammation, insulin resistance as well as lipodystrophy and adipogenesis modulation by Krüppel-like factors and miRNAs.

Potential Anti-obesogenic Effects of Ginkgo biloba Observed in Epididymal White Adipose Tissue of Obese Rats

Exacerbated expansion of adipose tissue seen in diet-induced obesity leads to endocrine dysfunction and disturbance in adipokine secretion, with such abnormal profile positively associated with type 2 diabetes and other mild chronic inflammatory conditions. Ginkgo biloba extract (GbE), a mixture of polyphenols with antioxidant properties, has been recently investigated in a variety of experimental models of endocrine dysfunction, with several potentially beneficial effects identified, including improvement in insulin sensitivity in obese rats, and reduction of weight gain in ovariectomy-induced obesity and diet-induced obesity. The aim of this study was to investigate in high fat diet-induced obese male rats the effects of GbE supplementation for 2 weeks on adipocyte volume and adipose tissue lipid accumulation. GbE supplementation was effective in reducing energy intake in obese rats compared to the saline-treated placebo group. Epididymal adipocyte volume was reduced in GbE-supplemented rats, as were epididymal [1-¹⁴C]-acetate incorporation into fatty acids, perilipin (Plin 1) and fatty acid synthase (Fasn) mRNA, and FAS protein levels. Adipocyte hypertrophy in obesity is associated with insulin resistance, and in the present study we observed a reduction in the adipocyte volume of GbE-supplemented obese rats to dimensions equivalent to adipocytes from non-obese rats. GbE supplementation significantly reduced acetate accumulation and tended to reduce [³H]-oleate incorporation, into epididymal adipose tissue, suggesting a potentially anti-obesogenic effect in longer term therapies. Further studies that investigate the effects of GbE supplementation in other experimental models are required to fully elucidate its suggested beneficial effects on mild chronic inflammatory conditions.

Distinct Roles for Peroxisomal Targeting Signal Receptors Pex5 and Pex7 in Drosophila

Peroxisomes are ubiquitous membrane-enclosed organelles involved in lipid processing and reactive oxygen detoxification. Mutations in human peroxisome biogenesis genes (Peroxin, PEX, or Pex) cause developmental disabilities and often early death. Pex5 and Pex7 are receptors that recognize different peroxisomal targeting signals called PTS1 and PTS2, respectively, and traffic proteins to the peroxisomal matrix. We characterized mutants of Drosophila melanogaster Pex5 and Pex7 and found that adult animals are affected in lipid processing. Pex5 mutants exhibited severe developmental defects in the embryonic nervous system and muscle, similar to what is observed in humans with PEX5 mutations, while Pex7 fly mutants were weakly affected in brain development, suggesting different roles for fly Pex7 and human PEX7. Of note, although no PTS2-containing protein has been identified in Drosophila, Pex7 from Drosophila can function as a bona fide PTS2 receptor because it can rescue targeting of the PTS2-containing protein thiolase to peroxisomes in PEX7 mutant human fibroblasts.

Ischemia-modified albumin: Crosstalk between fatty acid and cobalt binding

Myocardial ischemia is difficult to diagnose effectively with still few well-defined biochemical markers for identification in advance, or in the absence of myocardial necrosis. "Ischemia-modified albumin" (IMA), a form of albumin displaying reduced cobalt-binding affinity, is significantly elevated in ischemic patients, and the albumin cobalt-binding (ACB) assay can measure its level indirectly. Elucidating the molecular mechanism underlying the identity of IMA and the ACB assay hinges on understanding metal-binding properties of albumin. Albumin binds most metal ions and harbours four primary metal binding sites: site A, site B, the N-terminal site (NTS), and the free thiol at Cys34. Previous efforts to clarify the identity of IMA and the causes for its reduced cobalt-binding capacity were focused on the NTS site, but the degree of N-terminal modification could not be correlated to the presence of ischemia. More recent work suggested that Co2+ ions as used in the ACB assay bind preferentially to site B, then to site A, and finally to the NTS. This insight paved the way for a new consistent molecular basis of the ACB assay: albumin is also the main plasma carrier for free fatty acids (FFAs), and binding of a fatty acid to the high-affinity site FA2 results in conformational changes in albumin which prevent metal binding at site A and partially at site B. Thus, this review advances the hypothesis that high IMA levels in myocardial ischemia and many other conditions originate from high plasma FFA levels hampering the binding of Co2+ to sites A and/or B. This is supported by biophysical studies and the co-association of a range of pathological conditions with positive ACB assays and high plasma FFA levels.

Overactivation of the endocannabinoid system alters the antilipolytic action of insulin in mouse adipose tissue

Evidence has accumulated that obesity-related metabolic dysregulation is associated with overactivation of the endocannabinoid system (ECS), which involves cannabinoid receptor 1 (CB1R), in peripheral tissues, including adipose tissue (AT). The functional consequences of CB1R activation on AT metabolism remain unclear. Since excess fat mobilization is considered an important primary event contributing to the onset of insulin resistance, we combined in vivo and in vitro experiments to investigate whether activation of ECS could alter the lipolytic rate. For this purpose, the appearance of plasma glycerol was measured in wild-type and CB1R^-/- mice after acute anandamide administration or inhibition of endocannabinoid degradation by JZL195. Additional experiments were conducted on rat AT explants to evaluate the direct consequences of ECS activation on glycerol release and signaling pathways. Treatments stimulated glycerol release in mice fasted for 6 h and injected with glucose but not in 24-h fasted mice or in CB1R^-/-, suggesting that the effect was dependent on plasma insulin levels and mediated by CB1R. We concomitantly observed that Akt cascade activity was decreased, indicating an alteration of the antilipolytic action of insulin. Similar results were obtained with tissue explants exposed to anandamide, thus identifying CB1R of AT as a major target. This study indicates the existence of a functional interaction between CB1R and lipolysis regulation in AT. Further investigation is needed to test if the elevation of ECS tone encountered in obesity is associated with excess fat mobilization contributing to ectopic fat deposition and related metabolic disorders.

Regular activity breaks combined with physical activity improve postprandial plasma triglyceride, nonesterified fatty acid, and insulin responses in healthy, normal weight adults: A randomized crossover trial

BACKGROUND

Compared with prolonged sitting, regular activity breaks immediately lower postprandial glucose and insulin, but not triglyceride responses. Postprandial triglycerides can be lowered by physical activity but the effect is often delayed by ∼12 to 24 hours.

OBJECTIVE

The objective of the study was to determine whether regular activity breaks affect postprandial triglyceride response in a delayed manner similar to physical activity.

METHODS

In a randomized crossover trial, 36 adults (body mass index 23.9 kg/m² [standard deviation 3.9]) completed four 2-day interventions: (1) prolonged sitting (SIT); (2) prolonged sitting with 30 minutes of continuous walking (60% VO_2max), at the end of Day 1 (SIT + PA^D1); (3) Sitting with 2 minutes of walking (60% VO_2max) every 30 minutes (RAB); (4) A combination of the continuous walking and regular activity breaks in 2 and 3 above (RAB + PA^D1). Postprandial plasma triglyceride, nonesterified fatty acids, glucose, and insulin responses were measured in venous blood over 5 hours on Day 2.

RESULTS

Compared with SIT, both RAB (difference: -43.61 mg/dL·5 hours; 95% confidence interval [CI] -83.66 to -2.67; P = .035) and RAB + PA^D1 (-65.86 mg/dL·5 hours; 95% CI -112.14 to -19.58; P = .005) attenuated triglyceride total area under the curve (tAUC). RAB + PA^D1 produced the greatest reductions in insulin tAUC (-23%; 95% CI -12% to -31%; P < .001), whereas RAB resulted in the largest increase in nonesterified fatty acids (tAUC, 10.08 mg/dL·5 hours; 95% CI 5.60-14.84; P < .001). There was no effect on glucose tAUC (P = .290).

CONCLUSIONS

Postprandial triglyceride response is attenuated by regular activity breaks, when measured ∼24 hours after breaks begin. Combining regular activity breaks with 30 minutes of continuous walking further improves insulinemic and lipidemic responses.

PDE5 Inhibitor Tadalafil and Hydroxychloroquine Cotreatment Provides Synergistic Protection against Type 2 Diabetes and Myocardial Infarction in Mice

Diabetes is associated with a high risk for ischemic heart disease. We have previously shown that phosphodiesterase 5 inhibitor tadalafil (TAD) induces cardioprotection against ischemia/ reperfusion (I/R) injury in diabetic mice. Hydroxychloroquine (HCQ) is a widely used antimalarial and anti-inflammatory drug that has been reported to reduce hyperglycemia in diabetic patients. Therefore, we hypothesized that a combination of TAD and HCQ may induce synergistic cardioprotection in diabetes. We also investigated the role of insulin-Akt-mammalian target of rapamycin (mTOR) signaling, which regulates protein synthesis and cell survival. Adult male db/db mice were randomized to receive vehicle, TAD (6 mg/kg), HCQ (50 mg/kg), or TAD + HCQ daily by gastric gavage for 7 days. Hearts were isolated and subjected to 30-minute global ischemia, followed by 1-hour reperfusion in Langendorff mode. Cardiac function and myocardial infarct size were determined. Plasma glucose, insulin and lipid levels, and relevant pancreatic and cardiac protein markers were measured. Treatment with TAD + HCQ reduced myocardial infarct size (17.4% ± 4.3% vs. 37.8% ± 4.9% in control group, P < 0.05) and enhanced the production of ATP. The TAD + HCQ combination treatment also reduced fasting blood glucose, plasma free fatty acids, and triglyceride levels. Furthermore, TAD + HCQ increased plasma insulin levels (513 ± 73 vs. 232 ± 30 mU/liter, P < 0.05) with improved insulin sensitivity, larger pancreatic β-cell area, and pancreas mass. Insulin-like growth factor-1 (IGF-1) levels were also elevated by TAD + HCQ (343 ± 14 vs. 262 ± 22 ng/ml, P < 0.05). The increased insulin/IGF-1 resulted in activation of downstream Akt/mTOR cellular survival pathway. These results suggest that combination treatment with TAD and HCQ could be a novel and readily translational pharmacotherapy for reducing cardiovascular risk factors and protecting against myocardial I/R injury in type 2 diabetes.

Acetylshikonin from Zicao Prevents Obesity in Rats on a High-Fat Diet by Inhibiting Lipid Accumulation and Inducing Lipolysis

Various drugs have been developed to treat obesity, but these have undesirable secondary effects, and an efficient but non-toxic anti-obesity drug from natural sources is desired. This study investigated the anti-obesity effects and mechanisms of action of acetylshikonin (AS)—which is used in traditional Chinese medicine—in rats on a high-fat diet (HFD). Rats were fed a normal diet or an HFD; the latter group was received no treatment or were treated with 100, 300, or 900 mg/kg AS extract by intragastric administration for 6 weeks. In addition, 3T3-L1 adipocytes were treated with AS and the effects on adipogenesis and lipolysis were evaluated by western blot analysis of adipogenic transcription factors and lipid-metabolizing enzyme levels and the phosphorylation status of protein kinase (PK) A and hormone-sensitive lipase (HSL). AS prevented HFD-induced obesity including reduction in body weight, white adipose tissue content, liver mass, and serum triglyceride and free fatty acid levels in rats. It also suppressed the expression of adipogenic differentiation transcription factors and decreased the expression of the adipocyte-specific proteins HSL and adipose triglyceride lipase (ATGL). Furthermore, AS treatment induced lipolysis, leading to the release of glycerol and increased in PKA and HSL phosphorylation. These findings demonstrate that AS has anti-obesity effects in a rat model and may be a safe treatment for obesity in humans.

Fatty Acid-Binding Protein 4 (FABP4): Pathophysiological Insights and Potent Clinical Biomarker of Metabolic and Cardiovascular Diseases

Over the past decade, evidences of an integration of metabolic and inflammatory pathways, referred to as metaflammation in several aspects of metabolic syndrome, have been accumulating. Fatty acid-binding protein 4 (FABP4), also known as adipocyte FABP (A-FABP) or aP2, is mainly expressed in adipocytes and macrophages and plays an important role in the development of insulin resistance and atherosclerosis in relation to metaflammation. Despite lack of a typical secretory signal peptide, FABP4 has been shown to be released from adipocytes in a non-classical pathway associated with lipolysis, possibly acting as an adipokine. Elevation of circulating FABP4 levels is associated with obesity, insulin resistance, diabetes mellitus, hypertension, cardiac dysfunction, atherosclerosis, and cardiovascular events. Furthermore, ectopic expression and function of FABP4 in several types of cells and tissues have been recently demonstrated. Here, we discuss both the significant role of FABP4 in pathophysiological insights and its usefulness as a biomarker of metabolic and cardiovascular diseases.

FABP4 is secreted from adipocytes by adenyl cyclase-PKA- and guanylyl cyclase-PKG-dependent lipolytic mechanisms

OBJECTIVE

Fatty acid-binding protein 4 (FABP4) is expressed in adipocytes, and elevated plasma FABP4 level is associated with obesity-mediated metabolic phenotype. Postprandial regulation and secretory signaling of FABP4 has been investigated.

METHODS

Time courses of FABP4 levels were examined during an oral glucose tolerance test (OGTT; n=53) or a high-fat test meal eating (n=35). Effects of activators and inhibitors of adenyl cyclase (AC)-protein kinase A (PKA) signaling and guanylyl cyclase (GC)-protein kinase G (PKG) signaling on FABP4 secretion from mouse 3T3-L1 adipocytes were investigated.

RESULTS

FABP4 level significantly declined after the OGTT or a high-fat meal eating, while insulin level was increased. Treatment with low and high glucose concentration or palmitate for 2 h did not affect FABP4 secretion from 3T3-L1 adipocytes. FABP4 secretion was increased by stimulation of lipolysis using isoproterenol, a β3 -adrenoceptor agonist (CL316243), forskolin, dibutyryl-cAMP and atrial natriuretic peptide, and the induced FABP4 secretion was suppressed by insulin or an inhibitor of PKA (H-89), PKG (KT5823) or hormone sensitive lipase (CAY10499).

CONCLUSIONS

FABP4 is secreted from adipocytes in association with lipolysis regulated by AC-PKA- and GC-PKG-mediated signal pathways. Plasma FABP4 level declines postprandially, and suppression of FABP4 secretion by insulin-induced anti-lipolytic signaling may be involved in this decline in FABP4 level.

Nonesterified fatty acids and cardiovascular mortality in elderly men with CKD

BACKGROUND AND OBJECTIVES

Although nonesterified fatty acids (NEFAs) are essential as energy substrate for the myocardium, an excess of circulating NEFAs can be harmful. This study aimed to assess plausible relationships between serum NEFA and mortality due to cardiovascular disease (CVD) in individuals with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a prospective cohort study from the third examination cycle of the Uppsala Longitudinal Study of Adult Men, a population-based survey of 1221 elderly men aged 70-71 years residing in Uppsala, Sweden. Data collection took place during 1991-1995. All participants had measures of kidney function; this study investigated 623 (51.7%) of these patients with manifest CKD (defined as either eGFR<60 ml/min per 1.73 m(2) or urine albumin excretion rate ≥20 µg/min). Follow-up for mortality was done from examination date until death or December 31, 2007. After a median follow-up of 14 years (interquartile range, 8-16.8), associations of NEFAs with mortality (related to all causes, CVD, ischemic heart disease [IHD], or acute myocardial infarction) were ascertained.

RESULTS

The median serum NEFA was 14.1 mg/dl (interquartile range, 11.3-17.8). No association was found with measures of kidney function. Diabetes and serum triglycerides were the only multivariate correlates of NEFA. During follow-up, 453 participants died, of which 209 deaths were due to CVD, including 88 IHD deaths, with 41 attributed to acute myocardial infarction (AMI). In fully adjusted covariates, serum NEFA was an independent risk factor for all-cause mortality (hazard ratio [HR] per log2 increase, 1.22; 95% confidence interval [95% CI], 1.00 to 1.48) and CVD-related death (HR, 1.51; 95% CI, 1.15 to 1.99), including both IHD (HR, 1.51; 95% CI, 1.00 to 2.32) and AMI mortality (HR, 2.08; 95% CI, 1.09 to 3.98).

CONCLUSIONS

Elevated serum NEFA associated with CVD mortality, and particularly with mortality due to AMI, in a homogeneous population of older men with moderate CKD.

Effects of weight loss via high fat vs. low fat alternate day fasting diets on free fatty acid profiles

Cardiovascular disease risk is associated with excess body weight and elevated plasma free fatty acid (FFA) concentrations. This study examines how an alternate-day fasting (ADF) diet high (HF) or low (LF) in fat affects plasma FFA profiles in the context of weight loss, and changes in body composition and lipid profiles. After a 2-week weight maintenance period, 29 women (BMI 30-39.9 kg/m(2)) 25-65 years old were randomized to an 8-week ADF-HF (45% fat) diet or an ADF-LF (25% fat) diet with 25% energy intake on fast days and ad libitum intake on feed days. Body weight, BMI and waist circumference were assessed weekly and body composition was measured using dual x-ray absorptiometry (DXA). Total and individual FFA and plasma lipid concentrations were measured before and after weight loss. Body weight, BMI, fat mass, total cholesterol, LDL-C and triglyceride concentrations decreased (P < 0.05) in both groups. Total FFA concentrations also decreased (P < 0.001). In the ADF-LF group, decreases were found in several more FFAs than in the ADF-HF group. In the ADF-HF group, FFA concentrations were positively correlated with waist circumference. Depending on the macronutrient composition of a diet, weight loss with an ADF diet decreases FFA concentrations through potentially different mechanisms.

Counterregulation of insulin by leptin as key component of autonomic regulation of body weight

A re-examination of the mechanism controlling eating, locomotion, and metabolism prompts formulation of a new explanatory model containing five features: a coordinating joint role of the (1) autonomic nervous system (ANS); (2) the suprachiasmatic (SCN) master clock in counterbalancing parasympathetic digestive and absorptive functions and feeding with sympathetic locomotor and thermogenic energy expenditure within a circadian framework; (3) interaction of the ANS/SCN command with brain substrates of reward encompassing dopaminergic projections to ventral striatum and limbic and cortical forebrain. These drive the nonhomeostatic feeding and locomotor motivated behaviors in interaction with circulating ghrelin and lateral hypothalamic neurons signaling through melanin concentrating hormone and orexin-hypocretin peptides; (4) counterregulation of insulin by leptin of both gastric and adipose tissue origin through: potentiation by leptin of cholecystokinin-mediated satiation, inhibition of insulin secretion, suppression of insulin lipogenesis by leptin lipolysis, and modulation of peripheral tissue and brain sensitivity to insulin action. Thus weight-loss induced hypoleptimia raises insulin sensitivity and promotes its parasympathetic anabolic actions while obesity-induced hyperleptinemia supresses insulin lipogenic action; and (5) inhibition by leptin of bone mineral accrual suggesting that leptin may contribute to the maintenance of stability of skeletal, lean-body, as well as adipose tissue masses.

The production of nitric oxide, IL-6, and TNF-alpha in palmitate-stimulated PBMNCs is enhanced through hyperglycemia in diabetes

We examined nitric oxide (NO), IL-6, and TNF-α secretion from cultured palmitate-stimulated PBMNCs or in the plasma from type 2 diabetes mellitus (T2MD) patients or nondiabetic (ND) controls. Free fatty acids (FFA) have been suggested to induce chronic low-grade inflammation, activate the innate immune system, and cause deleterious effects on vascular cells and other tissues through inflammatory processes. The levels of NO, IL-6, TNF-α, and MDA were higher in supernatant of palmitate stimulated blood cells (PBMNC) or from plasma from patients. The results obtained in the present study demonstrated that hyperglycemia in diabetes exacerbates in vitro inflammatory responses in PBMNCs stimulated with high levels of SFA (palmitate). These results suggest that hyperglycemia primes PBMNCs for NO, IL-6, and TNF-alpha secretion under in vitro FFA stimulation are associated with the secretion of inflammatory biomarkers in diabetes. A combined therapy targeting signaling pathways activated by hyperglycemia in conjunction with simultaneous control of hyperglycemia and hypertriglyceridemia would be suggested for controlling the progress of diabetic complications.

Effects of a Pre-Exercise Meal on Plasma Growth Hormone Response and Fat Oxidation during Walking

The purpose of this study was to determine the effects of a pre-exercise meal on the plasma human growth hormone (hGH) response and fat oxidation during walking. Subjects (n=8) were randomly provided with either 1 g/kg body weight of glucose in 200 mL water (CHO) or 200 mL water alone (CON) 30 min prior to exercise and subsequently walked on a treadmill at 50% of VO2max for 60 min. Plasma hGH concentrations were significantly higher in subjects who received CHO compared to those who received CON at 15 and 30 min. The fat oxidation rate in the CHO was significantly lower than the CON while walking for 5~15, 25~35 and 45~55 min. Plasma FFA levels were also significantly lower in the CHO compared to the CON at 30, 45 and 60 min. Plasma glucose levels in the CHO were significantly lower while plasma insulin levels were significantly higher than in the CON at 15 and 30 min. Therefore, the results of this study suggest that the elevation of plasma hGH levels due to the intake of a pre-exercise meal may not be strongly related to fat oxidation and plasma free fatty acid (FFA) levels during low-intensity exercise.

Plasma free Fatty Acid concentrations as a marker for acute myocardial infarction

BACKGROUND

Acute myocardial infarction carries a high mortality among cardiac patients.The discovery of the fact that certain enzymes like CPK, LDH liberated into circulation following necrosis of the myocardial cells came as boon for physicians and patients. There has been a constant search of different parameters for the diagnosis and management of CoronaryArtery Diseases (CAD).

AIM

The present study was undertaken to investigate a possible relation between the changes in plasma free fatty acid (FFA) concentration and acute myocardial infarction.

MATERIAL AND METHODS

Fifty cases (25 males and 25 females) of acute myocardial infarction were selected for the present study. All the patients were in the age group of 40-70 years. For the control group fifty (25 male and 25 female) subjects of same age group were selected from patient's relatives and friends. Plasma free fatty acid concentration was estimated by Titrametric method of Trout et al., (1960), a modified version of Dole (1956).

STATISTICAL ANALYSIS

The statistical analysis of the data of the present study was done by using SPSS, version 14.0.1 was used.

RESULTS

Our study showed a significant increase in plasma FFA in the first 24 hours of acute myocardial infarction with subsequent normalisation on the 7th day.The difference between the first and the seventh day was statistically significant.

CONCLUSION

The FFA were found raised in cases of acute myocardial infarction.On the basis of present study, it is worth to say that estimation of serum free fatty acid should be done routinely at the earliest opportunity in all cases of acute myocardial infarction.

Adaptation of human adipose tissue to hypocaloric diet

Hypocaloric diet is a key component of the weight-reducing treatment of obesity and obesity-related disorders. Hypocaloric diets and the associated weight reduction promote improvement of metabolic profile of obese individuals. Among the mechanisms that underlie this beneficial metabolic outcome, the diet-induced modifications of morphological and functional characteristics of human adipose tissue (AT) are believed to have an important role. Prospective studies of hypocaloric weight-reducing dietary intervention demonstrate effects on adipocyte metabolism, namely lipolysis and lipogenesis, and associated changes of the adipocyte size. The endocrine function of AT, which involves cytokine and adipokine production by adipocytes, as well as by cells of stromavascular fraction, is also regulated by dietary intervention. Related inflammatory status of AT is modulated also as a consequence of the changes in recruitment of immune cells, mainly macrophages, in AT. Here, we give an overview of metabolic and endocrine modifications in human AT induced by a variety of hypocaloric diets.

Serum levels of leptin, adiponectin and resistin are interrelated and related to total antioxidant capacity, free fatty acids and phospholipids in early neonatal life

OBJECTIVES

The aims of this study were to determine interrelationships between serum leptin, adiponectin and resistin, insulin-like growth factor-1 (IGF-1), total antioxidant capacity (TAC), non-esterified fatty acids (NEFA) and phospholipids concentrations in infants.

DESIGN AND METHODS

A cross-sectional study was conducted to assess serum levels of leptin, adiponectin, resistin, IGF-1, TAC, NEFA and phospholipids in 45 breast-fed infants enrolled at 4-30 days after birth.

RESULTS

Serum leptin and adiponectin concentrations were positively correlated. Serum resistin concentrations were inversely correlated to serum leptin and adiponectin concentrations. Serum TAC was positively correlated to serum leptin and adiponectin, and inversely to serum resistin concentrations. Serum adiponectin concentrations were positively related to serum NEFA and phospholipid concentrations. Serum resistin concentrations were inversely related to serum NEFA, and phospholipid concentrations.

CONCLUSION

These data show that circulatory levels of leptin, adiponectin and resistin are interrelated and they apparently interact with the anti-oxidant system of infants.

Exercise therapy in type 2 diabetes

Structured exercise is considered an important cornerstone to achieve good glycemic control and improve cardiovascular risk profile in Type 2 diabetes. Current clinical guidelines acknowledge the therapeutic strength of exercise intervention. This paper reviews the wide pathophysiological problems associated with Type 2 diabetes and discusses the benefits of exercise therapy on phenotype characteristics, glycemic control and cardiovascular risk profile in Type 2 diabetes patients. Based on the currently available literature, it is concluded that Type 2 diabetes patients should be stimulated to participate in specifically designed exercise intervention programs. More attention should be paid to cardiovascular and musculoskeletal deconditioning as well as motivational factors to improve long-term treatment adherence and clinical efficacy. More clinical research is warranted to establish the efficacy of exercise intervention in a more differentiated approach for Type 2 diabetes subpopulations within different stages of the disease and various levels of co-morbidity.

Associations between estimated fatty acid desaturase activities in serum lipids and adipose tissue in humans: links to obesity and insulin resistance

Fatty acid composition of serum lipids and adipose tissue triacylglycerols (AT-TAG) partly reflect dietary fatty acid intake. The fatty acid composition is, besides the diet, also influenced by desaturating enzymes that can be estimated using product-to-precursor fatty acid ratios. The interrelationships between desaturase indices derived from different serum lipid fractions and adipose tissue are unclear, as well as their associations with obesity and insulin resistance. We aimed to investigate cross-sectional correlations between desaturase indices as measured in serum lipid fractions (phospholipids; PL and free fatty acids; FFA) and in adipose tissue (AT-TAG). In a population-based sample of 301 healthy 60-year-old men various desaturase indices were assessed: stearoyl-CoA-desaturase (16:1n-7/16:0; SCD-16 and 18:1n-9/18:0; SCD-18, respectively), delta-6-desaturase (20:3n-6/18:2n-6; D6D) and delta-5-desaturase (20:4n-6/20:3n-6; D5D). Correlations with BMI and insulin resistance (HOMA-IR) were also examined. SCD-16 and D5D were significantly correlated between fractions and tissues (all r > 0.30), whereas SCD-18 and D6D were not. Desaturase indices in serum FFA and AT-TAG were significantly correlated; SCD-16 (r = 0.63), SCD-18 (r = 0.37), and D5D (r = 0.43). In phospholipids, SCD-16 was positively correlated to BMI (r = 0.15), while D5D negatively to both BMI (r = -0.30) and HOMA-IR (r = -0.31), all p < 0.01. D6D in both phospholipids and AT-TAG was positively correlated to HOMA-IR and BMI (all p < 0.01). In conclusion, SCD-1 and D5D activity indices showed overall strong correlations between lipid pools. SCD-1 activity index in adipose tissue is best reflected by 16:1/16:0-ratio in serum FFA, but associations with obesity and insulin resistance differ between these pools. D5D in PL was inversely related to obesity and insulin resistance, whereas D6D index showed positive associations.

Ascorbic acid oral treatment modifies lipolytic response and behavioural activity but not glucocorticoid metabolism in cafeteria diet-fed rats

AIM

To analyse the effects of vitamin C (VC), a potent dietary antioxidant, oral supplementation on body weight gain, behavioural activity, lipolytic response and glucocorticoid metabolism in the early stages of diet-induced overweight in rats.

METHODS

Food intake, locomotive activity and faecal corticosterone were assessed during the 14 day trial period. After 2 weeks, the animals were sacrificed and the body composition, biochemical markers and lipolytic response from isolated adipocytes from retroperitoneal white adipose tissue were examined.

RESULTS

The intake of a high-fat diet by rats induced a significant increase in body weight, adiposity and insulin resistance markers as well as a decrease in faecal corticosterone levels compared with standard diet-fed rats. Interestingly, the animals fed on the cafeteria diet showed a significant increase in the isoproterenol-induced lipolytic response in isolated adipocytes. Furthermore, this cafeteria-fed group showed a reduced locomotive behaviour than the control rats. On the other hand, oral VC supplementation in animals receiving the high-fat diet restored the cafeteria diet effect in some of the analysed variables such as final body weight and plasma insulin to control group levels. Remarkably, increases in locomotive behaviour and a significant decrease in the lipolytic response induced by isoproterenol on isolated adipocytes from animals treated with VC were observed.

CONCLUSION

This work demonstrates that an oral ascorbic acid supplementation has direct effects on behavioural activity and on adipocyte lipolysis in early obesity stages in rats, which could indicate a protective short-term role of this vitamin against adiposity induced by chronic high-fat diet consumption.

What is the influence of menopausal status on metabolic profile, eating behaviors, and perceived health of obese women after weight reduction?

The duration of the numerous weight-loss studies that combine physical activity and diet varies from 3 to 14 months, and these studies have often considered pre- and postmenopausal women separately. The purpose of this study was to compare the effects of a 3-week weight-reducing program that combines caloric restriction and exercise on the metabolic profile, eating behaviors, and perceived health of sedentary obese pre- and postmenopausal women, after adjustment for age. In 10 pre- and 22 postmenopausal women, before and after weight loss, body composition, fasting lipid-lipoprotein profile, glucose and insulin levels, eating behaviors, and perceived health state were assessed. Body mass index, fat mass, and waist girth decreased after weight reduction in both groups (p < 0.0001). Reductions in fasting serum cholesterol and low-density lipoprotein-cholesterol levels were greater in pre- than in postmenopausal women (p < 0.0001), whereas triacylglycerol, glucose, and high-density lipoprotein-cholesterol levels decreased similarly in both groups (p < 0.05). Neither fasting insulin nor free fatty-acid concentrations were modified after weight loss in either group. Disinhibition (p < 0.005) and hunger scores on the three-factor eating questionnaire (TFEQ) (p < 0.05) and the state-anxiety score on the state-trait anxiety inventory (STAI) questionnaire (p < 0.0005) decreased in both groups, but restriction (TFEQ) increased (p < 0.01) and trait anxiety (STAI) decreased (p < 0.001) after weight reduction only in premenopausal women. Improvements in selected lipid-lipoprotein indices, eating behaviors, and perceived health-state components were better in pre- than in postmenopausal women, suggesting that menopausal status has an influence on some metabolic and behavioral responses to weight loss.

Attenuation of vascular/neural dysfunction in Zucker rats treated with enalapril or rosuvastatin

OBJECTIVE

Obese Zucker rats, animal model for the metabolic syndrome, develop a diabetes-like neuropathy that is independent of hyperglycemia. The purpose of this study was to determine whether drugs used to treat cardiovascular dysfunction in metabolic syndrome also protect nerve function.

METHODS AND PROCEDURES

Obese Zucker rats at 20 weeks of age were treated for 12 weeks with enalapril or rosuvastatin. Lean rats were used as controls. Vasodilation in epineurial arterioles was measured by videomicroscopy. Endoneurial blood flow (EBF) was measured by hydrogen clearance and nerve conduction velocity was measured following electrical stimulation of motor or sensory nerves.

RESULTS

Enalapril treatment decreased serum angiotensin-converting enzyme (ACE) activity and both drugs reduced serum cholesterol levels. In obese Zucker rats at 32 weeks of age superoxide levels were elevated in the aortas and epineurial arterioles, which were reduced by treatment with either drug. Nitrotyrosine levels were increased in epineurial arterioles and reduced with enalapril treatment. EBF was decreased and corrected by treatment with either drug. Motor nerve conduction velocity was decreased and significantly improved with enalapril treatment. Obese Zucker rats were hypoalgesic in response to a thermal stimulus and this was significantly improved with either treatment. Treatment with either enalapril or rosuvastatin significantly reversed the decrease in acetylcholine-mediated vascular relaxation of epineurial arterioles in obese Zucker rats.

DISCUSSION

Even though obese Zucker rats have normal glycemia vascular and neural dysfunctions develop with age and can be improved by treatment with either enalapril or rosuvastatin.

A single 1-h bout of evening exercise increases basal FFA flux without affecting VLDL-triglyceride and VLDL-apolipoprotein B-100 kinetics in untrained lean men

Our group (Magkos F, Wright DC, Patterson BW, Mohammed BS, Mittendorfer B, Am J Physiol Endocrinol Metab 290: E355-E362, 2006) has recently demonstrated that a single, prolonged bout of moderate-intensity cycling (2 h at 60% of peak oxygen consumption) in the evening increases basal whole-body free fatty acid (FFA) flux and fat oxidation, decreases hepatic VLDL-apolipoprotein B-100 (apoB-100) secretion, and enhances removal efficiency of VLDL-triglyceride (TG) from the circulation the following day in untrained, healthy, lean men. In the present study, we investigated the effect of a single, shorter-duration bout of the same exercise (1 h cycling at 60% of peak oxygen consumption) on basal FFA, VLDL-TG, and VLDL-apoB-100 kinetics in seven untrained, healthy, lean men by using stable isotope-labeled tracer techniques. Basal FFA rate of appearance in plasma and plasma FFA concentration were approximately 55% greater (P < 0.05) the morning after exercise than rest, whereas resting metabolic rate and whole-body substrate oxidation rates were not different after rest and exercise. Exercise had no effect on plasma VLDL-TG and VLDL-apoB-100 concentrations, hepatic VLDL-TG and VLDL-apoB-100 secretion rates, and VLDL-TG and VLDL-apoB-100 plasma clearance rates (all P > 0.05). We conclude that in untrained, healthy, lean men 1) the exercise-induced changes in basal whole-body fat oxidation, VLDL-TG, and VLDL-apoB-100 metabolism during the late phase of recovery from exercise are related to the duration of the exercise bout; 2) single sessions of typical recreational activities appear to have little effect on basal, fasting plasma TG homeostasis; and 3) there is a dissociation between systemic FFA availability and VLDL-TG and VLDL-apoB-100 secretion by the liver.

Oxidative mechanisms at rest and during exercise

Carbohydrates (CHO) and lipids provide the amount of energy required for physical and chemical reactions inside the human body. The various constraints the body has to resolve explain the use of these two substrates, catabolized via distinct pathways to one common final reaction. In the classic model, three main organs/tissues for substrate fluxes (liver, adipose tissue and skeletal muscle) and one organ regulating main reactions by adaptation of hormonal secretions (endocrine pancreas) are described. From this point of view, the only interactions between CHO and lipid metabolisms are mediated by glycaemic changes via insulin/glucagon ratio (IGR). However, according to recent advances, this concept seems to have a limited validity as it does take into account neither the many other interactions between CHO and lipid metabolism that are likely to occur in addition to the coarse control by IGR, nor the long-term regulation of energy balance, whose description began with the discovery of leptin. Moreover, it does not include the effects of energy expenditure. Therefore, this review focuses on three topics: (i) describe interactions between CHO and lipid metabolism at the level of each tissue and organ implied, via hormonal signaling as well as direct action of nutrients, (ii) integrate fluxes of substrates and signals between those tissues at rest in a global view of the metabolism taking into account short-term and long-term regulating factors and (iii) describe separately, to avoid confusion or extrapolation, the short-term and long-term influence of exercise on these regulation loops.