Acids In Human Adipose Tissue Research Articles

Home-made silver ion solid-phase extraction system for the analysis of trans fatty acids: comparison with commercial Discovery Ag-Ion SPE

A home-made silica-based silver ion solid-phase extraction (Ag+-SPE) system for the fractionation and subsequent gas chromatographic analysis of trans fatty acids in human adipose tissue is developed and examined. Analytical characteristics of the home-made Ag+-SPE column were compared with those of the commercial Discovery Ag-Ion SPE column and it was demonstrated that the both columns can be applied for the fractionation of fatty acid methyl esters.

Identification of Cyclopropaneoctanoic Acid 2‐Hexyl in Human Adipose Tissue and Serum

Fatty acids containing a cyclopropane ring in their structure (cyclopropane FA) have been found in a wide variety of bacteria, a number of protozoa, and Myriapoda. Little is known about cyclopropane FA in mammal, especially in human tissues. The present study deals with the identification of cyclopropane FA in adipose tissue and serum of humans and rats. Fatty acids extracted from the adipose tissue and serum obtained from obese women during bariatric surgery were methylated and analyzed on GC–MS. We have identified: cyclopropaneoctanoic acid 2-hexyl, cyclopropaneoctanoic acid 2-octyl, cyclopropanenonanoic acid, and 2-[[2-[(2-ethylcyclopropyl)methyl]cyclopropyl]methyl] acid in human adipose tissue. We confirmed the presence of cyclopropaneoctanoic acid 2-hexyl by derivatization of FA extracted from human adipose tissue to picolinyl esters. Cyclopropaneoctanoic acid 2-hexyl was the main cyclopropane FA (approximately 0.4 % of total fatty acids in human adipose tissue, and about 0.2 % of total fatty acids in the serum). In adipose tissue cyclopropaneoctanoic acid 2-hexyl was found mainly in triacylglycerols, whereas in serum in phospholipids and triacylglycerols. The cyclopropaneoctanoic acid 2-hexyl has also been found in serum, and adipose tissue of rats in amounts comparable to humans. The content of cyclopropaneoctanoic acid 2-hexyl decreased in adipose tissue of rats maintained on a restricted diet for 1 month. In conclusion, we demonstrated that cyclopropaneoctanoic acid 2-hexyl is present in human adipose tissue and serum. Adipose tissue cyclopropaneoctanoic acid 2-hexyl is stored mainly in triacylglycerols and the storage of this cyclopropane FA is affected by food restriction.

A Polydiacetylenes-Based Sensor for Discriminating Oleic Acid from Stearic Acid and Elaidic Acid

State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, ChinaReceived July 27, 2011, Accepted August 11, 2011Key Words : Polydiacetylenes, Sensor, Oleic acidOleic acid, a monounsaturated fatty acid, is the mostabundant fatty acid in human adipose tissue. As positivehealth effects, oleic acid may hinder the progression ofadrenoleukodystrophy (ALD), which is a fatal disease thataffects the brain and adrenal glands and attacks the myelinsheaths of the body, causing symptoms similar to those inmultiple sclerosis.

Paraoxonase 1 R/Q alleles are associated with differential accumulation of saturated versus 20:5n3 fatty acid in human adipose tissue

Serum paraoxonase 1 (PON1) function has been associated with human cardiovascular disease. The projected mechanism postulates interaction of PON1 with lipoproteins and insulin signaling resulting in alterations in lipid homeostasis. Recently, PON2 was shown to directly regulate triglyceride accumulation in macrophages and PON1 was detected in the interstitial space of adipocytes. The aims of the present study were a) to examine the relationship of the PON1 function with serum parameters related to lipid homeostasis, and b) to examine a possible role of PON1 in the regulation of lipid composition in the human adipose tissue. Two important genetic variations with functional impact on PON1 activity in humans are the Q192R and the L55M. The present study evaluated the impact of the Q192R and the L55M polymorphisms in a cross-section of the population on the island of Crete, as regards to PON1 activity, plasma lipids/lipoproteins, parameters of the metabolic syndrome, and the fatty acid composition of the adipose tissue. We detected a significant association of the polymorphisms with blood pressure, fasting blood glucose, triglycerides, apolipoprotein B, serum iron, and homocysteine. Furthermore, a novel function is suggested for PON1 on the fatty acid composition in the adipose tissue through the positive association of the R allele with saturated fatty acid and of the Q allele with 20:5n3 fatty acid deposition.

Fasted to Fed Trafficking of Fatty Acids in Human Adipose Tissue Reveals a Novel Regulatory Step for Enhanced Fat Storage

Absence or excess of adipose tissue are both associated with metabolic complications, implying the importance of well-functioning adipose tissue present in normal amounts. Adipose tissue sequesters dietary fat and thus protects other tissues from excess fat exposure, especially after meals. The objective of the study was the use of an integrative physiological technique to quantify trafficking of fatty acids (FAs) in adipose tissue over a 24 h period. Adipose tissue FA handling was studied in response to three meals in eight healthy men by the combination of arteriovenous blood sampling, tissue blood flow, and specific labeling of FA tracing of exogenous and endogenous fat by stable isotope methodology. The efficiency of adipose tissue FA uptake increased robustly with each meal. Chylomicron-triglyceride was the dominating source of FA. Adipose tissue fractional extraction of chylomicron-triglyceride increased from 21 +/- 4 to 47 +/- 8% (P = 0.03) between the first and last meal. Although adipose tissue lipoprotein lipase action increased with time (2-fold), there was an even greater increase in FA reesterification (3-fold), which led to a reduced spillover of chylomicron-derived FA, from 77 +/- 15 to 34 +/- 7% (P = 0.04) comparing the end of the first and the third meal period. Increased uptake of very low-density lipoprotein-derived FA was observed, but spillover of very low-density lipoprotein-derived FA was seen only in the fasting state. Human adipose tissue has a significant potential to up-regulate fat storage during a normal day that goes beyond increased lipoprotein lipase activation. The adaptation toward increasing fat storage may provide an explanation for the beneficial properties of normal amounts of adipose tissue.

In vitro and in vivo impairment of alpha2-adrenergic receptor-dependent antilipolysis by fatty acids in human adipose tissue.

The aim of the present study was to study the influence of fatty acids on the adrenergic control of lipolysis both in vitro and in vivo. Human subcutaneous adipose tissue explants were cultured for 48 h in the presence of 100 microM bromopalmitate (BrPal), and lipolysis was measured in isolated adipocytes. In control conditions, beta-AR-dependent activation of lipolysis by epinephrine was almost undetectable, and could be fully restored by pharmacological blockade of alpha2-AR-dependent antilipolysis. After BrPal treatment, epinephrine became fully lipolytic and was no longer influenced by alpha2-AR-blockade. Radioligand binding analysis revealed that BrPal treatment led to a significant reduction in the coupling of alpha2-AR to G proteins. In parallel, a chronic and significant increase in plasma fatty acids resulting from a 4-day high-fat diet (HFD) was accompanied by an impairment of the amplifying effect of the alpha2-AR antagonist phentolamine on exercise-induced lipolysis (measured in the subcutaneous adipose tissue with the use of a microdialysis probe) normally observed after a low-fat diet. In conclusion, in vitro and in vivo studies showed that fatty acids impair alpha2-AR-dependent antilipolysis.

Relation between the intake of milk fat and the occurrence of conjugated linoleic acid in human adipose tissue

Conjugated linoleic acid (CLA) is a group of naturally occurring fatty acids mainly present in fats from ruminants. CLA has been shown to be a potential anticarcinogen. In this study, the relation between bovine milk fat intake and the occurrence of CLA in human adipose tissue was investigated. One hundred twenty-three men weighed and recorded the foods they consumed for 1 wk. Afterward, recall interviews were conducted by telephone monthly for 7 consecutive months to inquire about food consumption during the previous 24 h. The entire dietary recording procedure was repeated once. The fatty acid composition of adipose tissue and serum was analyzed. The average amount of one isomer of CLA--9-cis,11-trans-octadecadienoic acid (9c,11t-18:2)--as a percentage of total fatty acids was found to be 0.50% in adipose tissue and 0.25% in serum. The amount of 9c,11t-18:2 in adipose tissue was significantly correlated with milk fat intake (r = 0.42). The percentage of 9c,11t-18:2 in both adipose tissue and in serum was strongly correlated with myristoleic acid (14:1). The amount of 9c,11t-18:2 in human adipose tissue was significantly related to milk fat intake.

Rapid determination of trans-fatty acids in human adipose tissue : Comparison of attenuated total reflection infrared spectroscopy and gas chromatography

A rapid attenuated total reflection (ATR) infrared (IR) spectroscopy procedure was used for quantitating the levels of total trans-fatty acid methyl ester (FAME) derivatives in neat (without solvent) test samples isolated from human adipose tissue. This procedure requires no weighing of the laboratory sample. The single-beam spectrum of the trans-containing FAMEs was `ratioed' against that of a reference material having only cis double bonds in order to obtain a symmetric absorption band at 966 cm −1 on a horizontal background. A single-reflection ATR diamond cell that requires only about 1 μl of neat FAMEs was used. The average level of trans-fatty acids in human adipose tissue found by ATR (3.07±0.27%) was generally higher than that obtained by gas chromatography (2.59±0.20%). Reasons for such a difference are discussed.

α‐Linolenic acid in human adipose tissue—A reply

α‐Linolenic acid in human adipose tissue—A reply

Correlation of isomeric fatty acids in human adipose tissue with clinical risk factors for cardiovascular disease

The relationships between the adipose tissue concentrations of 19 geometric and positional fatty acid isomers and 10 cardiovascular disease risk factors were determined in 76 free-living adult males. The percentages for trans isomers (total mean +/- SD 4.14 +/- 0.97%) and cis isomers (total mean +/- SD 2.91 +/- 0.34%) in adipose tissue generally agreed with dietary estimates based on the consumption of hydrogenated oils. A major exception was the percentage of 11c-18:1, which was twofold higher in adipose tissue. The total level of fatty acid isomers in adipose tissue or a factor (derived by factor analysis) that was representative of isomers of dietary origin was not significantly correlated with the cardiovascular risk factors. Only three trans isomers (11t-18:1, 12t-18:1, and 5t-14:1) and three cis isomers (11c-18:1, 13c-18:1, and 7c-16:1) were weakly correlated either positively or negatively with age, body mass index, plasma and lipoprotein cholesterol, and/or blood pressure (P less than 0.05, r greater than 0.231).

The noninvasive determination of linoleic acid content of human adipose tissue by natural abundance carbon-13 nuclear magnetic resonance.

A new method to assess noninvasively the proportionate storage of poly- and mono-unsaturated fatty acids in human adipose tissue is described. The method is based on in vivo natural abundance 13C NMR at 1.9 T using a TMR 32/200. Data were acquired with a concentric coil system placed below subcutaneous adipose tissue of the calf or the lower arm. Continuous single-frequency decoupling was used to optimize the signal in the spectral region of interest and minimize potential heating effects. Only adipose triglycerides contributed significantly to the resonance intensities. Typical linewidths for the in vivo 13C resonances were 10-14 Hz resulting in excellent resolution in the region of the unsaturated carbons. Signal-to-noise ratios for the resonance at 128.4 ppm (due to carbon atoms of polyunsaturated fatty acids) were typically 50-90 in 8 min using 0.25s repetition time. The relative storage of polyunsaturated fatty acids was determined by comparing the peak intensity at 128.4 ppm with the intensities of the peaks due to the carbonyl, the glycerol, or the main methyl carbons. High-resolution in vitro NMR of adipose biopsies and various mixtures of triglycerides studied with the in vivo NMR protocols provided further evidence that the described in vivo NMR methods allowed precise information on the relative storage of linoleic acid, the main constituent of the pool of polyunsaturated fatty acids. Conventional gas chromatography was performed on adipose biopsies of two volunteers and resulted in close agreement with the in vivo NMR methods. The average polyunsaturated fatty acid concentration in adipose tissue in seven healthy volunteers was 19.83 mol% +/- 1.74 (SD) as determined by in vivo NMR, consistent with conventional studies based on gas chromatography of biopsied material. Preliminary data on three cystic fibrosis patients showed a decreased polyunsaturated fatty acid concentration of 13.12 mol% +/- 2.73 (SD). The high accuracy of this method and its noninvasive character should be especially valuable in clinical research and diagnosis as repetitive adipose biopsies can be avoided.

Substrate cycling between triglyceride and fatty acid in human adipocytes

Substrate cycles in metabolism require energy and generate heat, and they may be involved in thermogenesis. We have studied one such cycle between triglyceride and fatty acid in isolated human adipocytes using a nonisotopic technique. In the absence of added hormone, and with 5 mmol/L (90 mg/dL) glucose in the incubation medium, lipolysis and fatty acid reesterification coexisted such that 40 ± 4% (mean ± SEM) of the fatty acid produced was cycled back into triglyceride. In 51 individual subjects the range was from 0% to 100%. Both lipolysis and the quantity of fatty acid recycled correlated positively with cell volume ( P < .001 and P < .005, respectively). Norepinephrine (10 −6 mol/L) alone (33 experiments) increased lipolysis 3.1-fold, and reduced the percentage of fatty acid reesterified. Cycling was similar to that in the basal state. Lipolysis was inhibited 46% by postabsorptive levels of insulin alone (18 experiments), but the proportion of fatty acid reesterified increased such that the quantity cycled back into triglyceride was similar to that observed in the basal state. In the presence of both norepinephrine and insulin (18 experiments), lipolysis was increased by 58% while 31 ± 4% of the fatty acid released was reesterified. In consequence, the quantity of fatty acid cycled back into triglyceride increased 2.1-fold. Increasing the insulin level fivefold or the medium glucose concentration to 20 mmol/L produced no further increase in the quantity of fatty acid reesterified. A substrate cycle exists, therefore, between triglyceride and fatty acid in human adipose tissue, and its activity is modified by norepinephrine and insulin. The predicted daily energy cost of this substrate cycle in 5 to 12 kcal (22 to 48 kJ) in lean subjects, and 10 to 20 kcal (41 to 82 kJ) in the obese.

Hydrogenated oils and fats: the presence of chemically-modified fatty acids in human adipose tissue

A total of 231 samples of adipose tissue has been analyzed for trans unsaturated acids which arise in large measure via consumption of hydrogenated fat; 136 specimens derived from patients who had died of ischemic heart disease (cases), the remainder being controls. They have also been analyzed by gas-liquid chromatography which gave information regarding the amounts of 1) "higher acids"--C20 plus C22 acids, mainly monoenoic--which derive from hydrogenated marine oils present in high amounts in certain margarines in the United Kingdom, and 2) "lower acids"--14:1 plus odd-numbered and branched chain acids in the C15 to C17 range--which are present in hydrogenated fat in lower amounts than in, say, butter-fat. Values of trans unsaturated acids tend to be higher, and values of lower acids lower for cases than controls, but we cannot at present conclude that these differences are statistically significant. Case versus control levels in respect of higher acids and linoleic acid do not appear to be significantly different.

The carbon pathway for lipogenesis in isolated adipocytes from rat, guinea pig, and human adipose tissue

The synthesis of fatty acids from a variety of labeled substrates by isolated adipocytes of the rat, guinea pig, and human was investigated. The incorporation of radioactive glucose and pyruvate into triglyceride fatty acids was considerably lower in human than either rat or guinea pig adipose tissue. By contrast, the incorporation of palmitate into adipose tissue triglycerides was approximately the same in all three species. End carbon analysis of fatty acids isolated from adipocytes incubated with pyruvate-U-14C indicated that although the synthesis of fatty acids in human adipose tissue was extremely low compared to that of the rat and guinea pig, it represented de novo biosynthesis rather than chain elongation of existing fatty acids. It is suggested that in the human, fatty acids are synthetised de novo primarily in the liver. In adipose tissue, lipogenesis consists essentially of the esterification of fatty acids, obtained from plasma, into triglycerides.

Release of glycerol and free fatty acids in human adipose tissue in vitro. Effect of the specimen size.

Release of glycerol and free fatty acids in human adipose tissue in vitro. Effect of the specimen size.