Fatty acid metabolism Research Papers (original) (raw)

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- Medicine, Pre Eclampsia, Fatty acid metabolism, Medical and Health Sciences

In recent years, the adipose tissue has emerged as an important endocrine organ. It is now recognized that besides storing energy the adipocytes also secrete several bioactive peptides, collectively called adipocytokines. Among these adipocytokines, leptin, the product of the ob gene, has been extensively investigated over the last decade. Skeletal muscle and adipose tissue, two major tissues involved in the regulation of glucose and fatty acids metabolism, have been consistently demonstrated to be directly affected by leptin. By binding to its receptors located in skeletal muscle and fat cells, leptin promotes energy dissipation and prevents fatty acid accumulation and 'lipotoxicity' in these tissues. On the other hand, under conditions of peripheral leptin resistance, such as observed in obese humans, the activation of pathways involved in fatty acid oxidation may be impaired. This leads to intracellular accumulation of lipid intermediates and causes insulin resistance. This review examines the metabolic pathways that are directly activated by leptin and how it regulates glucose and fatty acids metabolism in skeletal muscle and fat tissue. Furthermore, the impact of peripheral leptin resistance in these tissues leading to dysfunctional metabolic adaptations is also discussed.

- by Rolando Ceddia
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- Education, Nutrition, Metabolism, Adipose tissue

which began with a premature rupture of the fetal membranes. A normal female infant was delivered (43 cm, 1580 g, Apgar score after 3 min was 10). The baby developed normally and 3 months post partum weighed 5 kg.

- by Myron Genel
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- Fatty acids, Oxidoreductases, Hypoglycemia, Lancet

Increasing evidence from recent reports of drug-resistant mycobacterial strains poses a challenge worldwide. Drug-resistant strains often undergo mutations, adopt alternative pathways, and express drug efflux pumps to reduce or eliminate drug doses. Besides these intrinsic resistance mechanisms, bacteria can evade drug doses by forming biofilms. Biofilms are the concerted growth of adherent microorganisms, which can also be formed at the air-water interface. The growth is supported by the extracellular polymer matrix which is self-produced by the microorganisms. Reduced metabolic activity in a nutrient-deficient environment in the biofilm may cause the microorganisms to take alternative pathways that can make the microorganisms recalcitrant to the drug doses. Recent works have shown that Mycobacterium tuberculosis expresses several proteins during its growth in biofilm, those when deleted, did not show any effect on mycobacterial growth in normal nutrient-sufficient conditions. Studying these unconventional proteins in mycobacterial biofilms is therefore of utmost importance. In this article, I will discuss one such mycobacterial biofilm-related protein FabG4 that is recently shown to be important for mycobacterial survival in the presence of antibiotic stressors and limited nutrient condition. In an attempt to find more effective FabG4 inhibitors and its importance in biofilm forming M. tuberculosis, present knowledge about FabG4 and its known inhibitors are discussed. Based on the existing data, a putative role of FabG4 is also suggested.

- by Debajyoti Dutta
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- Biofilms, Mycobacterium tuberculosis, Drug Resistance, Fatty acid metabolism

Objective-To determine in the hearts of women with type-1 diabetes mellitus (T1DM), if the fate of extracted glucose is altered and if so what is the impact of dobutamine on myocardial substrate metabolism. Background-In experimental models of T1DM, myocardial glycolysis and glucose oxidation are reduced with the impairment becoming more pronounced with dobutamine. Whether similar changes in occur in humans with T1DM is unknown. Methods-Myocardial perfusion, oxygen consumption, glucose and fatty acid metabolism were measured with PET in 19 women, 7 normal volunteers (NV) and 12 with T1DM. The NV and 6 T1DM (DM1) were studied under baseline metabolic conditions and 6 T1DM studied during hyperinsulinemic-euglycemic clamp (DM1-C) both at rest and during dobutamine. Results-At rest, myocardial glucose uptake, glycolysis, glycogen storage and oxidation were reduced by similar levels in DM1 compared with NV (P < .05). During dobutamine, although myocardial glucose uptake was not different from DM1 at rest, fractional glycolysis was lower compared with NV or DM1-C and reflected a lower glucose oxidation rate (P < .001). Measurements of myocardial glucose metabolism at rest and during dobutamine were comparable between NV and DM1-C. During dobutamine, myocardial fatty acid uptake and oxidation increased in all 3 groups. Conclusions-In women with T1DM, 1) myocardial glucose metabolism is impaired downstream from initial uptake, 2) these abnormalities become more pronounced with dobutamine and are paralleled by an increase in myocardial fatty acid metabolism, and 3) insulin restores glucose metabolism to levels observed in normal controls.

- by C. Dence
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- Metabolism, Nuclear, Glucose, Insulin

Abnormal fatty acid metabolism and dyslipidemia play an intimate role in the pathogenesis of metabolic syndrome and cardiovascular diseases. The availability of glucose and insulin predominate as upstream regulatory elements that operate through a collection of transcription factors to partition lipids toward anabolic pathways. The unraveling of the details of these cellular events has proceeded rapidly, but their physiologic relevance to lifestyle modification has been largely ignored. Here we highlight the role of dietary input, specifically carbohydrate intake, in the mechanism of metabolic regulation germane to metabolic syndrome. The key principle is that carbohydrate, directly or indirectly through the effect of insulin, controls the disposition of excess dietary nutrients. Dietary carbohydrate modulates lipolysis, lipoprotein assembly and processing and affects the relation between dietary intake of saturated fat intake and circulating levels. Several of these processes are the subject of intense investigation at the cellular level. We see the need to integrate these cellular mechanisms with results from low-carbohydrate diet trials that have shown reduced cardiovascular risk through improvement in hepatic, intravascular, and peripheral processing of lipoproteins, alterations in fatty acid composition, and reductions in other cardiovascular risk factors, notably inflammation. From the current state of the literature, however, low-carbohydrate diets are grounded in basic metabolic principles and the data suggest that some form of carbohydrate restriction is a candidate to be the preferred dietary strategy for cardiovascular health beyond weight regulation.

- by Richard Feinman
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- Atherosclerosis, Cardiovascular disease, Cardiovascular Risk, Age

A 2 × 2 factorial 14-week feeding trial was conducted to evaluate the fatty acid metabolism in two different tilapia genotypes [Nile tilapia (Oreochromis niloticus, GIFT strain) and red hybrid tilapia (Oreochromis sp.)] fed a fish oil (FO)-or blended vegetable oil (BVO)-based semipurified diet. The BVO was formulated using olive oil (15%), sunflower oil (15%), linseed oil (30%) and refined, bleached, deodorized palm olein (40%) to mimic the major fatty acid classes of FO. In general, no significant effect (P N 0.05) of tilapia genotype or lipid source on fatty acid digestibility was observed. The fatty acid composition of tilapia whole-body, irrespective of genotype, was significantly (P b 0.05) affected by the dietary lipid source, but interestingly, tilapia fed the BVO diet which contained no polyunsaturated fatty acids (PUFA) longer than C18, recorded significant amounts of both n-6 and n-3 long chain (LC)-PUFA. The present study clearly indicated that tilapia farming can be a net producer of n-3 LC-PUFA. Using the whole-body fatty acid balance method, total fatty acid β-oxidation, Δ-5 and Δ-6 desaturation were observed to be significantly higher in fish fed the BVO diet compared to fish on the FO diet. No apparent Δ-5 desaturase activity on n-3 PUFA was observed in fish fed the FO diet. Both dietary lipid source and tilapia genotype elicited significant effects on the elongase activity on 18:4n-3, 18:2n-6 and 18:3n-6. Tilapia fed the BVO diet exhibited efficient bioconversion of 18:2n-6 to n-6 LC-PUFA indicating that the fatty acid metabolism of tilapia is able to fully compensate for the lack of dietary n-6 LC-PUFA when fed a vegetable oil-based diet. All fish showed active liponeogenesis suggesting that the addition of higher dietary levels of SFA and MUFA may be beneficial to tilapia. Irrespective of diet, GIFT tilapia showed higher rates of fatty acid neogenesis along with higher rates of elongation, Δ-5 and Δ-6 desaturation of both the n-6 PUFA and n-3 PUFA. The farming of improved strains of Nile tilapia may rely less heavily on marine-derived raw materials for aquafeed production.

- by Chaiw Yee Teoh
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- Zoology, Metabolism, Olive Oil, Aquaculture

Fatty liver disease is a common lipid metabolism disorder influenced by the combination of individual genetic makeup, drug exposure, and life-style choices that are frequently associated with metabolic syndrome, which encompasses obesity, dyslipidemia, hypertension, hypertriglyceridemia, and insulin resistant diabetes. Common to obesity related dyslipidemia is the excessive storage of hepatic fatty acids (steatosis), due to a decrease in mitochondria -oxidation with an increase in both peroxisomal -oxidation, and microsomal -oxidation of fatty acids through peroxisome proliferator activated receptors (PPARs). How steatosis increases PPAR activated gene expression of fatty acid transport proteins, peroxisomal and mitochondrial fatty acid -oxidation and -oxidation of fatty acids genes regardless of whether dietary fatty acids are polyunsaturated (PUFA), monounsaturated (MUFA), or saturated (SFA) may be determined by the interplay of PPARs and HNF4 with the fatty acid transport protein...

- by mohamed abdelmeged
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- Fatty Liver, Fatty Acid, PPAR, Biochemistry and cell biology

Atherosclerotic disease is the leading cause of both morbidity and mortality in patients with type 2 diabetes. In these patients, postprandial dyslipidemia include not only quantitative but also qualitative abnormalities of lipoproteins which are potentially atherogenic and seems to be a significant risk factor for cardiovascular disease since there is evidence that it results in endothelial dysfunction and enhanced oxidative stress. The most common pattern of postprandial dyslipidemia in diabetes consists of high concentrations of triglycerides, higher VLDLs production by the liver and a decrease in their clearance, a predominance of small dense LDL particles, and reduced levels of HDL. The cause of this postprandial dyslipidemia in diabetes is complex and involves a variety of factors including hyperinsulinemia, insulin resistance, hyperglycemia and disturbed fatty acid metabolism. Numerous clinical studies have shown that postprandial dyslipidemia is associated with endothelial dysfunction in type 2 diabetes and with alterations in other surrogate markers in the cascade of atherosclerosis. Current published guidelines indicate that in diabetics the primary lipid target is LDL b 100 mg/dL (70 mg/dL in very high-risk patients) and the most appropriate class of drugs are statins although the issue of postprandial dyslipidemia has not been specifically addressed so far. Moreover, several other classes of medications (fibrates, niacin and antidiabetic drugs) as well as non-pharmacological interventions (i.e. diet, smoking cessation and exercise) can be used to treat lipid and lipoprotein abnormalities associated with insulin resistance and type 2 diabetes. These type of interventions may be more appropriate to ameliorate postprandial dyslipidemia. However, this remains to be confirmed on clinical grounds.

- by Sokratis Pastromas
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- Cardiology, Atherosclerosis, Cardiovascular disease, Smoking Cessation

The ketogenic diet (KD) is designed to simulate the biochemical effects of fasting by maintaining a state of ketosis. The complex interplay of endocrine and metabolic factors requires that a continuous ingestion of a diet high in lipid calories is necessary to achieve such a state and yet maintain body weight. The resulting condition provides for much of the cerebral energy requirements in the form of ketone bodies. We review energy metabolism with special emphasis on fatty acid oxidation to provide the readers with a foundation that facilitates identification of patients who will especially benefit from this diet, as well as to assist clinicians in screening candidates who may experience a catastrophic outcome if fasted and placed on this diet. The review includes a discussion of the role of carnitine in mitochondrial fatty acid metabolism, and the criteria for carnitine supplementation. Only limited information is available regarding the interaction of the diet with the commonly used antiepileptic drugs.

- by Raman Sankar
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- Epilepsy, Energy Metabolism, Ketosis, Insulin

A 20-week growth trial was conducted to investigate the effect of two dietary blended vegetable oils (VO) on liver lipogenic enzyme activity, liver and gonad lipid class composition and fatty acid profiles, serum sex hormones, and gonad morphohistology in gilthead seabream, Sparus aurata. Three groups of fish (BW i 130.9 ± 3.1 g) were fed, close to satiation, three experimental diets: a control (CTRL) contained fish oil (FO) as the sole lipid source (100% FO) and two VO-blended diets in each 60% of FO was substituted by an equal mixture of cottonseed oil (CO), sunflower oil (SFO) and either linseed oil (LO) or soybean oil (SBO), designated as LO or SBO diet, respectively. Each diet was assigned to triplicate groups of fish. Results showed that all dietary treatments presented no significant (P [ 0.05) differences in growth rate and feed conversion ratio for sexes combined. Enzyme activities of liver lipogenic enzymes of LO-fed fish (glucose-6-phosphate dehydrogenase (G6PDH), malic enzyme (ME) and fatty acid synthetase (FAS)) were not statistically (P [ 0.05) different from those of CTRL fish. Only in the group of fish fed the SBO diet, G6PDH was slightly higher (P \ 0.05) for both sexes, while ME showed a significant (P \ 0.05) higher activity only in females relative to CTRL fish. Liver FAS enzyme activity remained unaltered among dietary groups. VO-fed fish recorded a significant (P \ 0.05) increase in total lipid (TL) and triglyceride (TAG) contents in both liver and gonad, more pronounced in females than in males, concurrent with a significant (P \ 0.05) decrease in cholesterol (CHL) and phospholipids (PL), more obvious for the SBO-fed fish, as compared to CTRL. The fatty acid (FA) composition of liver or gonad reflected that of the supplied diet and evidenced a significant (P \ 0.01 or \0.05) alteration in the majority of individual FA in VO-fed fish compared to CTRL. There were decreased levels of ARA (20:4 n-6), EPA (20:5 n-3), and DHA (22:6 n-3) in VO-fed fish, more pronounced in females than in males, compared to CTRL. The liver and gonad FA

- by Ebtisam Wassef
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- Principal Component Analysis, Sex Hormones, Aquaculture, Fish Oil

Atmospheric pressure photoionisation (APPI) was used in combination with silver-ion (Ag +)-HPLC for detection of (conjugated) fatty acid methyl esters (FAME) by tandem-mass spectrometry. APPI-MS of methyl esters of conjugated linoleic acid showed an increase in signal-to-noise ratio by a factor of 40 compared to atmospheric pressure chemical ionization in the positive mode. It was possible to identify double bond position, configuration and chain length of FAME based on chromatographic separation and mass detection. The developed LC-MS method is useful for the analysis of CLA elongation and ␤-oxidation products, especially with trans,trans-configuration, which are difficult to analyze by conventional GC-MS techniques.

- by Roland Geyer
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- Chemistry, Analytical Chemistry, Mass Spectrometry, Medicine

Despite identification twenty years ago of the gene responsible for cystic fibrosis transmembrane conductance regulator (CFTR), the protein defective in cystic fibrosis (CF), research of this monogenetic disease has not provided an explanation for the divergent symptoms, and a treatment breakthrough is still awaited. This review discusses different aspects of disturbances in lipid metabolism seen in CF. These include increased release of arachidonic acid (AA) from cell membrane phospholipids and a low status of linoleic and docosahexaenoic acids. Recent research has explored more complicated lipid associations. Disturbances in annexins and ceramides might act in concert to explain the impact on inflammation and AA release. The connections to CFTR and between the disturbances in essential fatty acid metabolism are reviewed. The metabolic interactions, some of which might be compensating, possibly explain the difficulties in understanding the fatty acid disturbances in relation to different symptoms and their relation to the defective CFTR.

- by Birgitta Strandvik
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- Cystic Fibrosis, Asthma, Fatty acids, Lipid metabolism
- by Ramon Colomer
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- Metabolism, Cancer, Breast Cancer, Pharmacokinetics

The aim of this study was to identify changes in the gene expression profile of Candida albicans upon exposure to the hydroxypyridone anti-infective agent ciclopirox olamine in an effort to better understand its mechanism of action. Methods: C. albicans SC5314 was exposed to either medium alone or ciclopirox olamine at a concentration equivalent to the IC 50 (0.24 mg/L) for 3 h. RNA was isolated and gene expression profiles were compared using DNA microarrays. Differential expression of select genes was confirmed by real-time reverse transcription (RT)-PCR. Mutants disrupted for CDR2 and both CDR1 and CDR2, as well as a clinical isolate overexpressing CDR1 and CDR2, were examined for changes in susceptibility to ciclopirox olamine. Results: A total of 49 genes were found to be responsive to ciclopirox olamine, including 36 up-regulated genes and 13 down-regulated genes. These included genes involved in small molecule transport (HGT11, HXT5, ENA22, PHO84, CDR4), iron uptake (FRE30, FET34, FTR1, FTR2, SIT1) and cell stress (SOD1, SOD22, CDR1, DDR48). Mutants disrupted for CDR2 and both CDR1 and CDR2, as well as a clinical isolate overexpressing CDR1 and CDR2, showed no change in susceptibility to ciclopirox olamine compared with the respective parent. Conclusions: Consistent with the hypothesis that ciclopirox olamine acts as an iron chelator, it induced changes in expression of many genes involved in iron uptake. Despite induction of the multidrug efflux pump genes CDR1 and, to a lesser extent, CDR2 by ciclopirox olamine, these genes do not affect susceptibility to this agent.

- by Larry Walker
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- Biological Chemistry, Gene expression, Biological Sciences, Cryptococcus Neoformans
- by Lakshmi Pulakat
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- Genetics, Metabolism, Molecular Medicine, Mitochondria

Rationale: It has been reported that each of three drugs effective in treating bipolar disorder (lithium, carbamazepine, and valproate) decreases the turnover of arachidonic acid (AA, 20:4n-6) in brain phospholipids of the awake rat. It is also known that lithium and carbamazepine do so without decreasing the turnover of docosahexaenoic acid (DHA, 22:6n-3). Objective: The aim of this study was to see whether valproate also specifically targets the turnover of AA but not of DHA in brain phospholipids. Methods: Valproate was administered (200 mg kg −1 , i.p.) to rats for 30 days to produce a therapeutically relevant plasma concentration and then determine its effect compared with that of vehicle on incorporation and turnover rates of DHA in brain phospholipids. In unanesthetized rats that had received valproate or vehicle, [1-14 C] DHA was infused intravenously, and arterial blood plasma was sampled until the animal was killed at 5 min; and its brain, after being microwaved, was subjected to chemical and radiotracer analysis. Results: Using equations derived from our fatty acid model, it was found that chronic valproate compared with vehicle did not alter the rate of incorporation or turnover of DHA in brain phospholipids. Valproate-treated animals had higher concentrations of linoleic acid (18:2n-6) in several brain phospholipids, supporting the hypothesis that it alters brain n-6 fatty acid metabolism. Conclusions: The results, comparable to published findings following chronic administration of lithium and carbamazepine to rats, support the hypothesis that drugs are effective against mania in bipolar disorder act by downregulating incorporation and turnover of AA, but not of DHA, in brain phospholipids.

- by Jagadeesh Rao
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- Chemistry, Psychopharmacology, Bipolar Disorder, Long Term Care

Hepatocellular carcinoma (HCC) represents a major health problem as it afflicts an increasing number of patients worldwide. Albeit most of the risk factors for HCC are known, this is a deadly syndrome with a life expectancy at the time of diagnosis of less than 1 year. Definition of the molecular principles governing the neoplastic transformation of the liver is an urgent need to facilitate the clinical management of patients, based on innovative methods to detect the disease in its early stages and on more efficient therapies. In the present study, we have combined the analysis of a murine model and human samples of HCC to identify genes differentially expressed early in the process of hepatocarcinogenesis, using a microarray-based approach. Expression of 190 genes was impaired in murine HCC from which 65 were further validated by low-density array real-time polymerase chain reaction (RT-PCR). The expression of the best 45 genes was then investigated in human samples resulting in 18 genes in which expression was significantly modified in HCC. Among them, JUN, methionine adenosyltransferase 1A and 2A, phosphoglucomutase 1, and acyl CoA dehydrogenase short/branched chain indicate defective cell proliferation as well as one carbon pathway, glucose and fatty acid metabolism, both in HCC and cirrhotic liver, a well-known preneoplastic condition. These alterations were further confirmed in public transcriptomic datasets from other authors. In addition, vasodilator-stimulated phosphoprotein, an actin-associated protein involved in cytoskeleton remodeling, was also found to be increased in the liver and serum of cirrhotic and HCC patients. In addition to revealing the impairment of central metabolic pathways for liver homeostasis, further studies may probe the potential value of the reported genes for the early detection of HCC.

- by Jose Alberto Suarez Mato
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- Genetics, Liver Cirrhosis, Hepatocellular Carcinoma, Life Expectancy

- by Spyridon Koulouris
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- Cardiology, Atherosclerosis, Cardiovascular disease, Smoking Cessation

Rapid cellular growth and multiplication, limited replicative senescence, calibrated sensitivity to apoptosis, and a capacity to differentiate into almost any cell type are major properties that underline the self-renewal capabilities of human pluripotent stem cells (hPSCs). We developed an integrated bioinformatics pipeline to understand the gene regulation and functions involved in maintaining such self-renewal properties of hPSCs compared to matched fibroblasts. An initial genome-wide screening of transcription factor activity using in silico binding-site and gene expression microarray data newly identified E2F as one of major candidate factors, revealing their significant regulation of the transcriptome. This is underscored by an elevated level of its transcription factor activity and expression in all tested pluripotent stem cell lines. Subsequent analysis of functional gene groups demonstrated the importance of the TFs to self-renewal in the pluripotency-coupled context; E2F directly targets the global signaling (e.g. self-renewal associated WNT and FGF pathways) and metabolic network (e.g. energy generation pathways, molecular transports and fatty acid metabolism) to promote its canonical functions that are driving the self-renewal of hPSCs. In addition, we proposed a core self-renewal module of regulatory interplay between E2F and, WNT and FGF pathways in these cells. Thus, we conclude that E2F plays a significant role in influencing the self-renewal capabilities of hPSCs.

- by Geoffrey Koh
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- Engineering, Physics, Chemistry, Gene regulation

The lipodystrophies are characterized by loss of adipose tissue in some anatomical sites, frequently with fat accumulation in nonatrophic depots and ectopic sites such as liver and muscle. Molecularly characterized forms include Dunnigan-type familial partial lipodystrophy (FPLD), partial lipodystrophy with mandibuloacral dysplasia (MAD), Berardinelli-Seip congenital generalized lipodystrophy (CGL), and some cases with Barraquer-Simons acquired partial lipodystrophy (APL). The associated mutant gene products include 1) nuclear lamin A in FPLD type 2 and MAD type A; 2) nuclear lamin B2 in APL; 3) nuclear hormone receptor peroxisome proliferator-activated receptor g in FPLD type 3; 4) lipid biosynthetic enzyme 1-acylglycerol-3phosphate O-acyltransferase 2 in CGL type 1; 5) integral endoplasmic reticulum membrane protein seipin in CGL type 2; and 6) metalloproteinase ZMPSTE24 in MAD type B. An unresolved question is whether metabolic disturbances are secondary to adipose repartitioning or result from a direct effect of the mutant gene product. Careful analysis of clinical, biochemical, and imaging phenotypes, using an approach called "phenomics," reveals differences between genetically stratified subtypes that can be used to guide basic experiments and to improve our understanding of common clinical entities, such as metabolic syndrome or the partial lipodystrophy syndrome associated with human immunodeficiency virus infection.

- by Robert Hegele
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- Genetics, Magnetic Resonance Imaging, Type 2 Diabetes, Metabolic syndrome

Lipids are the predominant source of energy for fish. The mechanisms by which fish allocate energy from lipids, for metabolism, development, growth and reproduction are critical for understanding key life history strategies and transitions. Currently, the major lipid component in aquaculture diets is fish oil (FO), derived from wild capture fisheries that are exploited at their maximum sustainable limit. The increasing demand from aquaculture for FO will soon exceed supply and threaten the viability of aquaculture. Thus, it is essential to minimize FO use in aquaculture diets. This might be achieved by a greater understanding of lipid storage and muscle growth, or the identification of alternatives to FO in feeds. This review focuses on recent research applying molecular and genomic techniques to the study of fin-fish lipid metabolism from an aquaculture perspective. Accordingly, particular emphasis will be given to fatty acid metabolism and to highly unsaturated fatty acid (HUFA) biosynthesis, and to the transcriptional mechanisms and endocrine factors that regulate these processes in fish. Comparative studies of gene function and distribution are described which, when integrated with recent fish genome sequence information, provide insights into lipid homeostasis and the outcomes associated with the replacement of FO in fish diets.

- by Grigorios Krey
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- Endocrinology, Zoology, Metabolism, Biological Sciences

BACKGROUND & AIMS: Hepatic lipotoxicity results from and contributes to obesity-related disorders. It is a challenge to study human metabolism of fatty acids (FAs) in the liver. We combined 11 C-palmitate imaging by positron emission tomography (PET) with compartmental modeling to determine rates of hepatic FA uptake, oxidation, and storage, as well as triglyceride release in pigs and human beings. METHODS: Anesthetized pigs underwent 11 C-palmitate PET imaging during fasting (n ϭ 3) or euglycemic hyperinsulinemia (n ϭ 3). Metabolic products of FAs were measured in arterial, portal, and hepatic venous blood. The imaging methodology then was tested in 15 human subjects (8 obese subjects); plasma 11 C-palmitate kinetic analyses were used to quantify systemic and visceral lipolysis. RESULTS: In pigs, PET-derived and corresponding measured FA fluxes (FA uptake, esterification, and triglyceride FA release) did not differ and were correlated with each other. In human beings, obese subjects had increased hepatic FA oxidation compared with controls (mean Ϯ standard error of the mean, 0.16 Ϯ 0.01 vs 0.08 Ϯ 0.01 mol/min/mL; P ϭ .0007); FA uptake and esterification rates did not differ between obese subjects and controls. Liver FA oxidation correlated with plasma insulin levels (r ϭ 0.61, P ϭ .016), adipose tissue (r ϭ 0.58, P ϭ .024), and systemic insulin resistance (r ϭ 0.62, P ϭ .015). Hepatic FA esterification correlated with the systemic release of FA into plasma (r ϭ 0.71, P ϭ .003). CONCLUSIONS: PET imaging can be used to measure FA metabolism in the liver. By using this technology, we found that obese individuals have increased hepatic oxidation of FA, in the context of adipose tissue insulin resistance, and increased FA flux from visceral fat. FA flux from visceral fat is proportional with the mass of the corresponding depot.

- by Kjell Någren
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- Gastroenterology, Obesity, Magnetic Resonance Imaging, Positron Emission Tomography

In order to study the mechanism(s) through which certain biologically active lipids, such as the hydroxyeicosanoids (HETEs), exert their effects, it is necessary to distinguish between binding of these lipids to cells and their cellular metabolism. A novel and simple method is described for the simultaneous determination of [3H]15-hydroxyeicosanoid (15-HETE) binding to cells and cellular [3H]15-HETE metabolism. The method involves initial separation of radiolabeled cells by filtration, filter extraction of cellular lipids by methanol, and thin-layer chromatography (or high performance liquid chromatography) determination of both nonesterified 15-HETE bound to cells and 15-HETE incorporation into cellular phospholipids. The method was applied to both PT-18 mast/basophil cells and rat basophilic leukemia (RBL-1) cells and should be applicable to other cells as well as other metabolizable hydroxy fatty acids or lipids.

- by Becky Vonakis
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- Eicosanoids, Fatty Acid, Radioligand Binding Assay, Thin Layer Chromatography

The nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylase SIRT1 has been linked to fatty acid metabolism via suppression of peroxysome proliferator-activated receptor gamma (PPAR-γ) and to inflammatory processes by deacetylating the transcription factor NF-κB. First, modulation of SIRT1 activity affects lipid accumulation in adipocytes, which has an impact on the etiology of a variety of human metabolic diseases such as obesity and insulin-resistant diabetes. Second, activation of SIRT1 suppresses inflammation via regulation of cytokine expression. Using high-throughput screening, the authors identified compounds with SIRT1 activating and inhibiting potential. The biological activity of these SIRT1-modulating compounds was confirmed in cell-based assays using mouse adipocytes, as well as human THP-1 monocytes. SIRT1 activators were found to be potent lipolytic agents, reducing the overall lipid content of fully differentiated NIH L1 adipocytes. In addition, the same...

- by michael entzeroth
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- Biology, Medicine, Cell line, Metabolic Bone Disease

Aims/hypothesis It is not known whether the beneficial effects of exercise training on insulin sensitivity are due to changes in hepatic and peripheral insulin sensitivity or whether the changes in insulin sensitivity can be explained by adaptive changes in fatty acid metabolism, changes in visceral fat or changes in liver and muscle triacylglycerol content. We investigated the effects of 6 weeks of supervised exercise in sedentary men on these variables. Subjects and methods We randomised 17 sedentary overweight male subjects (age 50±2.6 years, BMI 27.6±0.5 kg/ m 2) to a 6-week exercise programme (n=10) or control group (n=7). The insulin sensitivity of palmitic acid production rate (Ra), glycerol Ra, endogenous glucose Ra (EGP), glucose uptake and glucose metabolic clearance rate were measured at 0 and 6 weeks with a two-step hyperinsulinaemic-euglycaemic clamp [step 1, 0.3 (low dose); step 2, 1.5 (high dose) mU kg −1 min −1 ]. In the exercise group subjects were studied >72 h after the last training session. Liver and skeletal muscle triacylglycerol content was measured by magnetic resonance spectroscopy and visceral adipose tissue by cross-sectional computer tomography scanning. Results After 6 weeks, fasting glycerol, palmitic acid Ra (p=0.003, p=0.042) and NEFA concentration (p=0.005) were decreased in the exercise group with no change in the control group. The effects of low-dose insulin on EGP and of high-dose insulin on glucose uptake and metabolic clearance rate were enhanced in the exercise group but not in the control group (p=0.026; p=0.007 and p=0.04). There was no change in muscle triacylglycerol and liver fat in either group. Conclusions/interpretation Decreased availability of circulating NEFA may contribute to the observed improvement in the insulin sensitivity of EGP and glucose uptake following 6 weeks of moderate exercise.

- by Kevin Baynes
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- Endocrinology, Computed Tomography, Life Style, Biology

- by Martin Whyte
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- Endocrinology, Computed Tomography, Life Style, Biology

The metabolism of palmitate and erucate has been investigated in hepatocytes isolated from control rats and from rats fed 0.3% clofibrate. Clofibrate increased the oxidation of [ 1-14C] palmitate 1.5 to 2-fold while the esterification was decreased. At a high concentration of palmitate (1.5 mM), the total rate of fatty acid metabolism was stimulated. Clofibrate stimulated both the oxidation (3.5 to 5-fold) and the esterification (1.7-fold) of [14-14C]erucate. Erucate undergoes chain-shortening in isolated liver cells. This chain-shortening was stimulated at least 2-fold by clofibrate feedings. The isolated mitochondrial fraction from clofibrate-fed rats showed an increased capacity for oxidation of short-chain acylcarnitines (including acetylcarnitine), while the oxidation of palmitoyl-and erucoylcarnitine showed little change. It is suggested that erucate is shortened by the recently detected 3-oxidation system of peroxisomes.

- by Harald Osmundsen
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- Engineering, Chemistry, Medicine, Lipids

Previous genetic and proteomic studies identified altered activity of various enzymes such as those of fatty acid metabolism and glycogen synthesis after a single toxic dose of valproic acid (VPA) in rats. In this study, we demonstrate the effect of VPA on metabolite synthesis flux rates and the possible use of abnormal 13 C labeled glucosederived metabolites in plasma or urine as early markers of toxicity. Female CD-1 mice were injected subcutaneously with saline or 600 mg/kg) VPA. Twelve hours later, the mice were injected with an intraperitoneal load of 1 g/kg [U-13 C]-D-glucose. 13 C isotopomers of glycogen glucose and RNA ribose in liver, kidney and brain tissue, as well as glucose disposal via cholesterol and glucose in the plasma and urine were determined. The levels of all of the positional 13 C isotopomers of glucose were similar in plasma, suggesting that a single VPA dose does not disturb glucose absorption, uptake or hepatic glucose metabolism. Threehour urine samples showed an increase in the injected tracer indicating a decreased glucose re-absorption via kidney tubules. 13 C labeled glucose deposited as liver glycogen or as ribose of RNA were decreased by VPA treatment; incorporation of 13 C via acetyl-CoA into plasma cholesterol was significantly lower at 60 min. The severe decreases in glucose-derived carbon flux into plasma and kidney-bound cholesterol, liver glycogen and RNA ribose synthesis, as well as decreased glucose re-absorption and an increased disposal via urine all serve as early flux markers of VPA-induced adverse metabolic effects in the host. Keywords Valproic acid Á Stable isotope-based dynamic metabolic profiling (SiDMAP) Á [U-13 C 6 ]-D-glucose The views presented here do not necessarily reflect those of the U.S. Food and Drug Administration.

- by Z. Sarnyai
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- Genetics, Analytical Chemistry, Developmental Biology, Molecular Medicine
- by Linda Peterson
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- Type 2 Diabetes, Type 2 Diabetes Mellitus, Fatty acid metabolism

To prepare medium-chain-length poly-3-hydroxyalkanoates (PHAs) with altered physical properties, we generated recombinant Escherichia coli strains that synthesized PHAs with altered monomer compositions. Experiments with different substrates (fatty acids with different chain lengths) or different E. coli hosts failed to produce PHAs with altered physical properties. Therefore, we engineered a new potential PHA synthetic pathway, in which ketoacyl-coenzyme A (CoA) intermediates derived from the ␤-oxidation cycle are accumulated and led to the PHA polymerase precursor R-3-hydroxyalkanoates in E. coli hosts. By introducing the poly-3-hydroxybutyrate acetoacetyl-CoA reductase (PhbB) from Ralstonia eutropha and blocking the ketoacyl-CoA degradation step of the ␤-oxidation, the ketoacyl-CoA intermediate was accumulated and reduced to the PHA precursor. Introduction of the phbB gene not only caused significant changes in the monomer composition but also caused changes of the physical properties of the PHA, such as increase of polymer size and loss of the melting point. The present study demonstrates that pathway engineering can be a useful approach for producing PHAs with engineered physical properties.

- by Michele Kellerhals
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- Biology, Medicine, Multidisciplinary, Recombinant DNA Technology

Background Water deficit has significant effects on grape berry composition resulting in improved wine quality by the enhancement of color, flavors, or aromas. While some pathways or enzymes affected by water deficit have been identified, little is known about the global effects of water deficit on grape berry metabolism. Results The effects of long-term, seasonal water deficit on berries of Cabernet Sauvignon, a red-wine grape, and Chardonnay, a white-wine grape were analyzed by integrated transcript and metabolite profiling. Over the course of berry development, the steady-state transcript abundance of approximately 6,000 Unigenes differed significantly between the cultivars and the irrigation treatments. Water deficit most affected the phenylpropanoid, ABA, isoprenoid, carotenoid, amino acid and fatty acid metabolic pathways. Targeted metabolites were profiled to confirm putative changes in specific metabolic pathways. Water deficit activated the expression of numerous transcript...

- by laurent Deluc
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- Genomics, Biology, Carotenoids, Medicine

Gene expression in Petunia inflata petals undergoes major changes following compatible pollination. Severe flower wilting occurs reproducibly within 36 hours, providing an excellent model for investigation of petal senescence and programmed cell death. Expression of a number of genes and various enzyme activities involved in the degradation and remobilization of macromolecules have been found to be upregulated during the early stages of petal senescence. By performing differential display of cDNAs during Petunia inflata petal senescence, a highly upregulated gene encoding a cytochrome P450 was identified. Analysis of the complete cDNA sequence revealed that the predicted protein is a member of the CYP74C family (CYP74C9) and is highly similar to a tomato CYP74C allene oxide synthase (AOS) that is known to be active on 9-hydroperoxides. Cloning of the petunia genomic DNA revealed an intronless gene with a promoter region that carries signals found in stress-responsive genes and poten...

- by Maureen Hanson
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- Microbiology, Plant Biology, Biology, Apoptosis

A low vs. high glycemic index of a high-fat (HF) diet (LGI and HGI, respectively) significantly retarded adverse health effects in adult male C57BL/6J mice, as shown recently (Van Schothorst EM, Bunschoten A, Schrauwen P, Mensink RP, Keijer J. FASEB J 23: 1092–1101, 2009). The LGI diet enhanced whole body insulin sensitivity and repressed HF diet-induced body and white adipose tissue (WAT) weight gain, resulting in significantly reduced serum leptin and resistin levels and increased adiponectin levels. We questioned how WAT is modulated and characterized the molecular mechanisms underlying the glycemic index-mediated effects using whole genome microarrays. This showed that the LGI diet mainly exerts its beneficial effects via substrate metabolism, especially fatty acid metabolism. In addition, cell adhesion and cytoskeleton remodeling showed reduced expression, in line with lower WAT mass. An important transcription factor showing enhanced expression is PPAR-γ. Furthermore, serum le...

- by Erik Verlinde
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- Biology, Cell Adhesion, Medicine, Molecular Mechanics

Background: Digital gene expression profiling was used to characterize the assembly of genes expressed in equine skeletal muscle and to identify the subset of genes that were differentially expressed following a ten-month period of exercise training. The study cohort comprised seven Thoroughbred racehorses from a single training yard. Skeletal muscle biopsies were collected at rest from the gluteus medius at two time points: T 1-untrained, (9 ± 0.5 months old) and T 2-trained (20 ± 0.7 months old). Results: The most abundant mRNA transcripts in the muscle transcriptome were those involved in muscle contraction, aerobic respiration and mitochondrial function. A previously unreported over-representation of genes related to RNA processing, the stress response and proteolysis was observed. Following training 92 tags were differentially expressed of which 74 were annotated. Sixteen genes showed increased expression, including the mitochondrial genes ACADVL, MRPS21 and SLC25A29 encoded by the nuclear genome. Among the 58 genes with decreased expression, MSTN, a negative regulator of muscle growth, had the greatest decrease. Functional analysis of all expressed genes using FatiScan revealed an asymmetric distribution of 482 Gene Ontology (GO) groups and 18 KEGG pathways. Functional groups displaying highly significant (P < 0.0001) increased expression included mitochondrion, oxidative phosphorylation and fatty acid metabolism while functional groups with decreased expression were mainly associated with structural genes and included the sarcoplasm, laminin complex and cytoskeleton. Conclusion: Exercise training in Thoroughbred racehorses results in coordinate changes in the gene expression of functional groups of genes related to metabolism, oxidative phosphorylation and muscle structure.

- by BWAMBALE JOHN
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- Functional Analysis, Gene expression, Biological Sciences, Mice

Free fatty acid (FFA) oxidation is depressed in severe heart failure due to reduced activity of mitochondrial fatty acid oxidation enzymes. It is unknown whether the concomitant enhancement in cardiac glucose use is a consequence of reduced FFA oxidation, or also due to potentiation of the carbohydrate oxidative pathway. FFA and glucose oxidation rates were measured in vivo in 9 normal dogs and 9 dogs with pacing-induced heart failure by infusing 3 H-oleate and 14 C-glucose. FFA oxidation was lower (39 ± 9 vs. 73 ± 5 nmol min-1 g-1), while glucose oxidation was higher (42 ± 8 vs. 17 ± 6 nmol min-1 g-1) in failing compared to normal hearts (P < 0.05). At the end of the in vivo experiment, clamp-frozen biopsies were harvested from the left ventricle. Messenger RNAs encoding for proteins involved in both glucose and fatty acid metabolism, and for citrate synthase, were significantly reduced. Protein expression of GLUT-1 and GLUT-4, and GLUT-4 translocation to the sarcolemma showed no significant differences between the two groups despite a significant reduction in mRNAs with heart failure. GAPDH mRNA, protein expression, and activity were all reduced. The E2 subunit of pyruvate dehydrogenase was decreased both at the mRNA and protein level, with no effect on either fractional or maximal activity. In conclusion, we found either no changes or moderate downregulation of key enzymes of the carbohydrate metabolism in failing hearts, which suggests that the increase in glucose oxidation in vivo was principally due to impaired FFA oxidation and that the maximal myocardial capacity to obtain energy from substrate is globally depressed.

- by Vincenzo Lionetti
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- Biopsy, Heart Failure, Dogs, Glucose

MicroRNAs (miRNAs) are recently discovered, noncoding, small regulatory RNA molecules that negatively regulate gene expression. Although many miRNAs are identified and validated in many plant species, they remain largely unknown in Brassica rapa (AA 2n =, 20). B. rapa is an important Brassica crop with wide genetic and morphological diversity resulting in several subspecies that are largely grown for vegetables, oilseeds, and fodder crop production. In this study, we identified 186 miRNAs belonging to 55 families in B. rapa by using comparative genomics. The lengths of identified mature and pre-miRNAs ranged from 18 to 22 and 66 to 305 nucleotides, respectively. Comparison of 4 nucleotides revealed that uracil is the predominant base in the first position of B. rapa miRNA, suggesting that it plays an important role in miRNA-mediated gene regulation. Overall, adenine and guanine were predominant in mature miRNAs, while adenine and uracil were predominant in pre-miRNA sequences. One DNA sequence producing both sense and antisense mature miRNAs belonging to the BrMiR 399 family, which differs by 1 nucleotide at the, 20 th position, was identified. In silico analyses, using previously established methods, predicted 66 miRNA target mRNAs for 33 miRNA families. The majority of the target genes were transcription factors that regulate plant growth and development, followed by a few target genes that are involved in fatty acid metabolism, glycolysis, biotic and abiotic stresses, and other cellular processes. Northern blot and qRT-PCR analyses of RNA samples prepared from different B. rapa tissues for 17 miRNA families revealed that miRNAs are differentially expressed both quantitatively and qualitatively in different tissues of B. rapa.

- by Vignesh Dhandapani
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- Genetics, Gene regulation, MicroRNA, Comparative Genomics

We aimed to clarify the incidence and the clinicopathological value of non-muscle myoglobin (Mb) in a large cohort of non-invasive and invasive breast cancer cases. Matched pairs of breast tissues from 10 patients plus 17 breast cell lines were screened by quantitative PCR for Mb mRNA. In addition, 917 invasive and 155 non-invasive breast cancer cases were analysed by immunohistochemistry for Mb expression and correlated to clinicopathological parameters and basal molecular characteristics including oestrogen receptor-alpha (ERalpha)/progesteron receptor (PR)/HER2, fatty acid synthase (FASN), hypoxia-inducible factor-1alpha (HIF-1alpha), HIF-2alpha, glucose transporter 1 (GLUT1) and carbonic anhydrase IX (CAIX). The spatial relationship of Mb and ERalpha or FASN was followed up by double immunofluorescence. Finally, the effects of estradiol treatment and FASN inhibition on Mb expression in breast cancer cells were analysed. Myoglobin mRNA was found in a subset of breast cancer cell ...

- by M. Dietel
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- Data Mining, Breast Cancer, Immunohistochemistry, Cell line

Thyroid hormones have widespread cellular effects; however it is unclear whether their effects on the central nervous system (CNS) contribute to global energy balance. Here we demonstrate that either whole-body hyperthyroidism or central administration of triiodothyronine (T3) decreases the activity of hypothalamic AMP-activated protein kinase (AMPK), increases sympathetic nervous system (SNS) activity and upregulates thermogenic markers in brown adipose tissue (BAT). Inhibition of the lipogenic pathway in the ventromedial nucleus of the hypothalamus (VMH) prevents CNS-mediated activation of BAT by thyroid hormone and reverses the weight loss associated with hyperthyroidism. Similarly, inhibition of thyroid hormone receptors in the VMH reverses the weight loss associated with hyperthyroidism. This regulatory mechanism depends on AMPK inactivation, as genetic inhibition of this enzyme in the VMH of euthyroid rats induces feeding-independent weight loss and increases expression of the...

- by Donald Morgan
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- Genetics, Biology, Medicine, Nature

It was recently shown that, as in yeast, alcohols selectively increase the hemolytic properties of certain staphylococci strains. This phenomenon has been called 'microbial alcohol-conferred hemolysis'(MACH). Here we present the changes in gene expression by Staphylococcus aureus 8325-4, in response to ethanol. Ethanol upregulated the expression of multiple toxins and increase the pathogen potential of S. aureus strain 8325-4. Ethanol also increased the level of genes considered necessary for production and viability of biofilm, such as: icaAD, sdrDE, pyr, and ure. Increased urease activity appeared to be an important factor in the ethanol response along with macromolecule repair mechanisms. Oxidative-stress responses, such as increased expression of sodA1, sodA2 and upregulation of zinc-containing alcohol dehydrogenase, alcohol-acetaldehyde dehydrogenase (adhE) and two aldehyde dehydrogenases (aldA1, aldA2), which can generate more reducing power, were also induced. Upregulation of fatty acid metabolism appears to be important in enabling the bacteria to handle excess amounts of ethanol which ultimately may lead to synthesis of lytic lypids. The patterns of regulation were confirmed by quantitive reverse transcriptase PCR (QRT-PCR). These results, taken together, suggest that exposure to ethanol increases pathogenic traits and induce oxidative-stress responses.

- by Mel Rosenberg
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- Microbiology, Immunology, Biofilms, Medical Microbiology

The CYP4A gene subfamily is composed of a number of genes that encode cytochromes P450 from various species, including human, which catalyze the hydroxylation of various saturated and unsaturated fatty acids, including arachidonic acid and prostaglandins. CYP4A7, a fatty acid metabolizing cytochrome P450 from rabbit kidney, was expressed in E. coli by adding the first 10 codons of CYP17␣ producing final yields of 20 nmol/L in order to perform detailed kinetic and spectral studies. CYP4A7 metabolized arachidonate, laurate, and myristate, with maximum turnover numbers of 152, 130, and 64.5 min ؊1 and corresponding K m values of 74.5, 27, and 16.7 M, respectively, in the presence of cytochrome b 5. In the absence of cytochrome b 5 , CYP4A7 metabolized laurate and myristate with turnover numbers of 27.4 and 33.6 min ؊1 and corresponding K m values of 3.9 and 33 M, respectively. Arachidonate was not metabolized in the absence of cytochrome b 5. Saturation kinetics studies performed with heme-depleted cytochrome b 5 (apo cytochrome b 5) yielded turnover numbers of 118 and 74 min ؊1 and K m values of 74 and 25 M with laurate and myristate, respectively, indicating that cytochrome b 5 is not involved in electron transfer but rather plays a conformational role. Laurate perturbation of the visible absorption spectrum of CYP4A7 allowed for determination of the spectral binding constant (K S) in the absence and presence of cytochrome b 5 (13 and 43 M, respectively). In stopped-flow kinetics experiments, the flavin reduction (ϳ90 s ؊1) and heme reduction (ϳ9 s ؊1) phases of the monooxygenase reaction of CYP4A7 were not altered by the presence of cytochrome b 5. Estimations of the rate of CPR (0.3 s ؊1) or cytochrome b 5 (9.1 s ؊1) binding with CYP4A7 were also determined.

- by Bettie Masters
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- Kinetics, Kidney, Carbon Monoxide, Fatty acids

Background: Disarrangement in fatty acids and oxidative stress are features of cystic fibrosis. Cholesterol is very sensitive to oxidative stress. Objectives: The objectives were to examine whether cholesterol oxidation products are altered in cystic fibrosis and whether they are associated with fatty acids and with characteristics of the disease state. Design: 7-Ketocholesterol and 7b-hydroxycholesterol (prototype molecules of free radical-mediated cholesterol oxidation) and the fatty acid profile were assessed by mass spectrometry in patients and in sex-and age-matched control subjects. Results: Compared with control subjects, mean (6SD) cholesterol oxidation was higher (7-ketocholesterol: 11.31 6 5.1 compared with 8.33 6 5.5 ng/mL, P = 0.03; 7b-hydroxycholesterol: 14.5 6 6.8 compared with 9.7 6 4.1 ng/mL, P = 0.004), total saturated fatty acids were higher (31.90 6 1.93% compared with 30.31 6 0.98%, P , 0.001), monounsaturated fatty acids were higher (29.14 6 3.85% compared with 25.88 6 2.94%, P = 0.004), x-6 (n23) polyunsaturated fatty acids were lower (34.84 6 4.77 compared with 39.68 6 2.98%, P , 0.0001), and x-3 polyunsaturated fatty acids were comparable in patients with cystic fibrosis. Oxysterols were inversely associated with 24:0 and 18:2 x-6 fatty acids but did not correlate with the increased oleic acid or with any of the x-3 fatty acids. Conclusions: Cystic fibrosis is characterized by relevant cholesterol oxidation that is associated with an abnormal fatty acid profile. The interplay between oxysterols and fatty acids potentially provides insight into the biological mechanisms that underlie this complex disease.

- by Mona Boaz
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- Engineering, Metabolism, Mass Spectrometry, Cystic Fibrosis

The n) 3 polyunsaturated fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have important nutritional benefits in humans. Farmed fish could serve as promising sources of EPA/DHA, but they need these fatty acids or their precursors in their diets. Here we transferred masu salmon D6-desaturase-like gene in zebrafish to increase its ability for synthesizing EPA and DHA. Expression of this gene in transgenic fish elevated their EPA content by 1.4-fold and DHA by 2.1-fold. On the other hand, the a-linolenic acid (ALA) content decreased, it being a substrate of D6-desaturase, while the total lipid remained constant. This achievement demonstrates that fatty acid metabolic pathway in fish can be modified by the transgenic technique, and perhaps this could be applied to tailor farmed fish as even better sources of valuable human food.

- by Shuichi Satoh
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- Technology, Aquaculture, Biological Sciences, Salmon

Elongation of very long chain fatty acids 4 (ELOVL4) is a novel member of the ELO family of genes that are involved in fatty acid metabolism. ELOVL4 encodes a putative transmembrane protein of 314 amino acids that carries a possible endoplasmic reticulum (ER) retention/retrieval signal (KXKXX) at the C-terminus. Two distinct mutations, a 5-bp deletion and a complex mutation from the same region in exon 6 of this gene, have been reported so far and are associated with autosomal dominant atrophic macular degeneration (adMD/STGD3). Both of these deletions could result in C-terminal truncation and loss of the ER retention signal in the mutant protein. We expressed the wildtype and mutant proteins in COS-7 and CHO cells to study the intracellular distribution of ELOVL4 and to identify possible implications of the above mutations in its localization. Immunofluorescence analysis of these proteins along with organelle marker antibodies revealed predominant ER localization for wild-type ELOVL4. Targeted deletion of the dilysine motif at the C-terminus of the protein resulted in the loss of ER localization. Immunoelectron microscopy and immunofluorescence analysis revealed a similar ER localization pattern for the protein in human photoreceptors. These data indicate that ELOVL4 is an ER-resident protein, which supports its suggested function in fatty acid elongation. We also demonstrate that the localization of both mutant proteins was dramatically changed from an ER to a Golgi distribution. Our observations suggest that the consequences of defective protein trafficking could underlie the molecular mechanism associated with degeneration of the macula in the patients with adMD/STGD3.

- by Monica Jablonski
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- Information Systems, Genetics, Genomics, Fluorescence Microscopy

lz31 15(p-iodophenyl)-3(R,S)-methylpentadecanoic acid (BMIPP) myocardial scintigraphy and exercise stress thallium (Tl)-201 myocardial scintigraphy were performed in 17 patients with hypertrophic cardiomyopathy (HCM) to evaluate the existence of abnormal fatty acid metabolism in the myocardium and the relationship between this abnormality and myocardial ischemia. On the BMIPP scintigraphy, abnormalities were found in 12 of 17 patients (71%). Five patients showing no abnormalities on the BMIPP scintigraphy had well preserved exercise tolerance and had longer exercise duration than the others showing BMIPP scintigraphic abnormalities (P < 0.001). On the evaluation of the segmental abnormalities, Tl scintigraphic abnormalities were found in 15 (50%) of 30 segments showing decreased accumulation of BMIPP. On the other hand, BMIPP scintigraphic abnormalities were found in all segments showing decreased accumulation of Tl. The sites of decreased accumulation of BMIPP and Tl were in good agreement with the sites of wall hypertrophy. Four patients showing BMIPP scintigraphic abnormalities and no Tl scintigraphic abnormalities were in higher New York Heart Association functional classes, had shorter exercise duration (P < 0.05) than the 5 patients showing no abnormalities on either scintigraphy. It is concluded that abnormalities of fatty acid metabolism in the heart are detected at a high rate in patients with HCM, and may be due in part to factors other than myocardial perfusion disturbance.

- by J. Taki
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- Cardiology, Fatty acids, Aged, Single Photon Emission Computed Tomography

Saturated (SFA) and monounsaturated (MUFA) fatty acids, the most abundant fatty acid species, have many divergent biological effects including the regulation of cell proliferation, programmed cell death and lipid-mediated cytotoxicity. Their distribution is regulated by Stearoyl-CoA Desaturases (SCD), the enzymes that convert SFA into MUFA. A positive correlation between high levels of tissue MUFA and several types of cancer has been reported, but a causal relationship between the function of SCD1, the main human SCD isoform, and cancer development has not yet been firmly established. Here we report that the stable knockdown of SCD1 gene expression in A549 human lung adenocarcinoma cells decreased the ratio MUFA/SFA in total lipids and inhibited the incorporation of glucose into cell lipids. Cell proliferation and anchorage-independent growth were considerably decreased in SCD1-depleted cells, whereas the rate of apoptosis was elevated, with respect to control A549 cells. In addition, phosphorylation of Akt-Ser473 and GSK-3ß-Ser9 was found notably impaired in SCD1-ablated A549 cells. Interestingly, the effects of SCD1 blockade on Akt activation, cancer cell growth and apoptosis could not be reversed by exogenously added oleic acid. Remarkably, the reduction of SCD1 expression in lung cancer cells significantly delayed the formation of tumors and reduced the growth rate of tumor xenografts in mice. Our study demonstrates that SCD1 activity regulates Akt activation and determines the rate of cell proliferation, survival and invasiveness in A549 cancer cells and shows, for the first time, that SCD1 is a key factor in the regulation of tumorigenesis in vivo.

- by michel narce
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- Engineering, Physics, Chemistry, Biology

Background Abnormalities in myocardial metabolism and/or regulatory genes have been implicated in left ventricular systolic dysfunction. However, the extent to which these modulate left ventricular diastolic function (LVDF) is uncertain. Methods Independent component analysis was applied to extract latent LVDF traits from 14 measured echocardiography-derived endophenotypes of LVDF in 403 Caucasians. Genetic association was assessed between measured and latent LVDF traits and 64 single nucleotide polymorphisms (SNPs) in three peroxisome proliferator-activated receptor (PPAR)-complex genes involved in the transcriptional regulation of fatty acid metabolism. Results By linear regression analysis, 7 SNPs (4 in PPARA, 2 in PPARGC1A, 1 in PPARG) were significantly associated with the latent LVDF trait, whereas a range of 0-4 SNPs were associated with each of the 14 measured echocardiography-derived endophenotypes. Frequency distribution of P values showed a greater proportion of significa...

Several adipose-derived cytokines (adipokines) have been suggested to act as a link between accumulated fat mass and altered insulin sensitivity. Resistin and tumour necrosis factor-alpha (TNF-a) have been implicated in impairing insulin sensitivity in rodents; conversely, two other adipokines, leptin and adiponectin, increase insulin sensitivity in lean and obese rodents. Currently, there is considerable focus on the concept that lipid accumulation in skeletal muscle leads to the development of insulin resistance. Adiponectin and leptin have each been demonstrated to increase rates of fatty acid (FA) oxidation and decrease muscle lipid content, which may in part be the underlying mechanism to their insulin sensitizing effect. These effects on FA metabolism appear to be mediated in part through the activation of AMP-activated protein kinase. Evidence derived from animal and human studies suggests that the ability of leptin and adiponectin to stimulate FA oxidation in muscle is impaired in the obese condition. Thus, leptin and adiponectin resistance may be an initiating factor in the accumulation of intramuscular lipids, such as diacylglyerol and ceramide, and the ensuing development of insulin resistance. Lifestyle factors such as diet and exercise are able to restore the sensitivity of muscle to leptin. The actual physiological roles of resistin and TNF-a in altering muscle lipid metabolism are more controversial, but each has been shown to directly impair insulin signalling and consequently, insulin stimulated glucose uptake in muscle. However, the possibility that resistin and TNF-a reduces insulin sensitivity in muscle by directly impairing FA metabolism in this tissue leading to lipid accumulation, has been virtually unexamined. Thus, the contribution of various adipokines to the development of insulin resistance is complex and not fully understood. Finally, the effects of these adipokines on metabolism and insulin sensitivity are generally studied in isolation, making it difficult to predict the interactive effects and the net impact on insulin sensitivity.

- by David Dyck
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- Obesity, Skeletal muscle biology, Insulin Resistance, Glucose

Background-Both physiologic and pathophysiologic conditions affect the myocardium's substrate use and consequently, its structure, function, and adaptability. The effect of sex on myocardial oxygen, glucose, and fatty acid metabolism in humans is unknown. Methods and Results-We studied 25 young subjects (13 women) using positron emission tomography quantifying myocardial blood flow, oxygen consumption (MVO 2), glucose and fatty acid extraction and metabolism. MVO 2 , was higher in women compared with men (5.74±1.08 vs. 4.26±0.69μmol•g −1 •min −1 , p<.005). Myocardial glucose extraction fraction, and utilization were lower in women compared with men (0.025±.019 vs. 0.062±0.028, p<.001 and 133±96 vs. 287±164 nmol•g −1 •min −1 , p<.01). There were no sex differences in myocardial blood flow, fatty acid metabolism, plasma glucose, fatty acid, or insulin levels. Female sex was an independent predictor of increased MVO 2 (p=.01), decreased myocardial glucose extraction fraction and utilization (p<. 005, and < .05, respectively). Insulin sensitivity was an independent predictor of increased myocardial glucose extraction fraction and utilization (p<.01, and p=.01). Conclusions-Further studies are necessary to elucidate the mechanisms responsible for sexassociated differences in myocardial metabolism. However, the presence of such differences may provide a partial explanation for the observed sex-related differences in the prevalence and manifestation of a variety of cardiac disorders. Keywords sex; myocardial metabolism; glucose; myocardial oxygen consumption Myocardial metabolism and cardiac function are inextricably linked: the myocardium metabolizes substrates in order to generate ATP, the hydrolysis of which allows for cardiac function. In the postnatal myocardium, metabolism of fatty acids provide most of the energy required; glucose, and to a lesser degree lactate, ketones, intracellular triglyceride, and glycogen also provide energy. However, the myocardium may switch its preference away from

- by Pablo Soto
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- Nuclear, Echocardiography, Glucose, Insulin