High Levels Of Free Fatty Acids Research Articles

Palmitate Activates Autophagy in INS-1E β-Cells and in Isolated Rat and Human Pancreatic Islets

We have investigated the in vitro effects of increased levels of glucose and free fatty acids on autophagy activation in pancreatic beta cells. INS-1E cells and isolated rat and human pancreatic islets were incubated for various times (from 2 to 24 h) at different concentrations of glucose and/or palmitic acid. Then, cell survival was evaluated and autophagy activation was explored by using various biochemical and morphological techniques. In INS-1E cells as well as in rat and human islets, 0.5 and 1.0 mM palmitate markedly increased autophagic vacuole formation, whereas high glucose was ineffective alone and caused little additional change when combined with palmitate. Furthermore, LC3-II immunofluorescence co-localized with that of cathepsin D, a lysosomal marker, showing that the autophagic flux was not hampered in PA-treated cells. These effects were maintained up to 18–24 h incubation and were associated with a significant decline of cell survival correlated with both palmitate concentration and incubation time. Ultrastructural analysis showed that autophagy activation, as evidenced by the occurrence of many autophagic vacuoles in the cytoplasm of beta cells, was associated with a diffuse and remarkable swelling of the endoplasmic reticulum. Our results indicate that among the metabolic alterations typically associated with type 2 diabetes, high free fatty acids levels could play a role in the activation of autophagy in beta cells, through a mechanism that might involve the induction of endoplasmic reticulum stress.

Infusion of a Lipid Emulsion in Healthy Men Decreases the Serotonergic Response

Subjects with obesity and insulin resistance display a low response to a serotonergic challenge test. One of the hallmarks of obesity and insulin resistance is elevated plasma free fatty acids (FFAs). We hypothesize that increasing plasma FFA by infusion of a lipid emulsion, may be a contributing component leading to decreased serotonergic responsivity in healthy young men. Ten lean healthy men, 23.6 ± 5.0 years and BMI 22.6 ± 1.9 kg/m², were included. Serotonergic responsivity was assessed using the prolactin response to infusion with citalopram, a selective serotonin reuptake inhibitor, which is a validated tool to assess serotonergic tone. All participants received a lipid/heparin emulsion (Intralipid) infusion during 6 h. Saline infusion was used as a control. To evaluate a possible effect of heparin per se on prolactin, four out of the ten subjects also received heparin only during 6 h without the serotonergic challenge test. Plasma prolactin increased by 74.3 ± 15.5% during saline infusion. Intralipid infusion increased plasma FFA from 0.5 ± 0.05 to 2.3 ± 0.2 mmol/l (p < 0.001). The increase in plasma prolactin during Intralipid infusion was significantly lower (39.3 ± 10%; p < 0.001 compared to saline infusion). Heparin infusion per se increased plasma prolactin by 14.0 ± 1.9%. We found that during the Intralipid infusion with concomitant high plasma FFA levels the serotonergic response was decreased in healthy young men. Higher FFA levels may be the mediator of the decreased serotonergic response reported in patients with insulin resistance and obesity.

Mangiferin Decreases Plasma Free Fatty Acids through Promoting Its Catabolism in Liver by Activation of AMPK

Mangiferin has been shown to have the effect of improving dyslipidemia. Plasma free fatty acids (FFA) are closely associated with blood lipid metabolism as well as many diseases including metabolic syndrome. This study is to investigate whether mangiferin has effects on FFA metabolism in hyperlipidemic rats. Wistar rats were fed a high-fat diet and administered mangiferin simultaneously for 6 weeks. Mangiferin (50, 100, 150 mg/kg BW) decreased dose-dependently FFA and triglycerides (TG) levels in plasma, and their accumulations in liver, but increased the β-hydroxybutyrate levels in both plasma and liver of hyperlipidemic rats. HepG2 cells were treated with oleic acid (OA, 0.2 mmol/L) to simulate the condition of high level of plasma FFA in vitro, and were treated with different concentrations of mangiferin simultaneously for 24 h. We found that mangiferin significantly increased FFA uptake, significantly decreased intracellular FFA and TG accumulations in HepG2 cells. Mangiferin significantly increased AMP-activated protein kinase (AMPK) phosphorylation and its downstream proteins involved in fatty acid translocase (CD36) and carnitine palmitoyltransferase 1 (CPT1), but significantly decreased acyl-CoA: diacylgycerol acyltransferase 2 (DGAT2) expression and acetyl-CoA carboxylase (ACC) activity by increasing its phosphorylation level in both in vivo and in vitro studies. Furthermore, these effects were reversed by Compound C, an AMPK inhibitor in HepG2 cells. For upstream of AMPK, mangiferin increased AMP/ATP ratio, but had no effect on LKB1 phosphorylation. In conclusion, mangiferin decreased plasma FFA levels through promoting FFA uptake and oxidation, inhibiting FFA and TG accumulations by regulating the key enzymes expression in liver through AMPK pathway. Therefore, mangiferin is a possible beneficial natural compound for metabolic syndrome by improving FFA metabolism.

Comparison of blends of conventional diesel fuel and CRBO containing high levels of FFA in a DI diesel engine

This work attempts to analyse the ability of high free fatty acid (FFA) crude rice bran oil (CRBO) in replacing diesel partially in a compression ignition (CI) engine. It was observed that the delay period and the maximum rate of pressure rise for CRBO blends are lower than diesel and is almost inversely proportional to FFA content. Maximum heat release rate for CRBO blends are lower and occur earlier than that of diesel. CRBO blends require longer duration to release 90% of heat than diesel and it decreases with increase in FFA content of CRBO. When operating with CRBO blends, all emission parameters were decreased significantly with a marginal increase in CO emission than that of diesel without affecting the brake thermal efficiency of the engine. It is concluded that higher FFA of CRBO blends does not inhibit its ability to be utilised as a fuel in CI engines.

Mitochondria and Endoplasmic Reticulum in Diabetes and Its Complications

Mitochondria and Endoplasmic Reticulum in Diabetes and Its Complications

Solid superacid catalyzed glycerol esterification of free fatty acids in waste cooking oil for biodiesel production

AbstractThe free fatty acids (FFAs) of waste cooking oil (WCO) are readily esterified with crude glycerol in the presence of the solid superacid SO/ZrO2–Al2O3. This reaction lowers the acidity of WCO before biodiesel production. The solid superacid SO/ZrO2–Al2O3 catalyzes both FFA esterification and TAG glycerolysis during the reaction. The conversion of FFA in the WCO with an acid value of 88.4 ± 0.5 mg KOH/g to acylglycerols was 98.4% under optimal conditions (mole ratio of glycerol to FFA = 1.4:1; reaction time = 4 h; reaction temperature = 200°C; catalyst loading = 0.3 wt%) obtained through an orthogonal experiment. The final FAME product with a FAME content of 96.9 ± 0.3 wt% yield was 94.8 wt%, after transesterification of the esterified WCO with methanol, catalyzed by potassium hydroxide. The FAME composition of the products produced by transesterification were identified and quantified by GC–MS. The results suggest that this new glycerol esterification process, using a solid superacid catalyst, affords a promising method to convert oils with high FFA levels, like WCO, to biodiesel. The process has the inherent advantage of easy separation steps for removing excess alcohol and significant savings in energy, when compared to acid catalyzed reactions with methanol to lower acidity.Practical applications: In this work, WCO with a high acid value was esterified with crude glycerol catalyzed by solid super acid, whose formula was expressed as SO/ZrO2–Al2O3. There are distinct advantages to this new esterification process, which include easy separation of the excess crude glycerol by sedimentation or centrifugation, the use of the low cost reactant crude glycerol direct from the byproducts of transesterification, the potential to achieve a very low content of FFAs by post‐refining to improve the yield of the final product, and time and energy saving are found as compared to the traditional methanol esterification process. This new technology provides a promising alternative method for processing feedstocks of high acid value, such as WCO, for the production of biodiesel.

Functional classification of ESTs from vernonia (Vernonia galamensis L.) cDNA library

The Vernonia galamensis (Cass.) Less [synonym: Centrapalus pauciflorus] Compositae, is a source of naturally epoxidized oil. Its commercial use is limited due to presence of a lipase enzyme that produces high free fatty acid levels in vernonia oil. The genomic information and the gene expression patterns of lipase in vernonia has not been studied in detail. The objectives of our studies were to construct a complementary DNA (cDNA) library from vernonia seed to identify expressed sequence tags (ESTs) related to various plant functions. We were successful in constructing a cDNA library from seed tissues of vernonia. A total of 1325 cDNA clones were randomly sequenced and analyzed. A total of 97 high-quality ESTs with an average length of 400bp were generated. These ESTs indicated the existence of genes involved in varied functions such as defense, protein processing, transcription, translation, signal transduction, and secondary metabolism. Out of the total EST sequences, there were 129 ESTs containing simple sequence repeats (SSRs) from which 63 SSR primer pairs were designed. It is the first transcriptome report from the vernonia that has generated ESTs as well as EST derived SSR markers capable of being used in future oil quality, transformation and germplasm characterization studies.

High free fatty acids level related with cardiac dysfunction in obese rats

AimTo determine whether reducing free fatty acids (FFAs) concentration has a protective effect on cardiac structure and function in high-fat-diet-induced obese rat. MethodsSprague–Dawley rats were randomly divided into normal control, obesity and fenofibrate group. After 8 or 16 weeks, the maximum velocity of myocardial contraction (+dP/dt) and diastole (−dP/dt) were measured. The concentrations of triglyceride, FFAs and angiotensin II were measured. Mitochondrial cytochrome C release and protein levels of NF-kappa B (NF-κB) and inducible nitric oxide synthase (iNOS) in myocardium were analyzed. ResultsThe triglyceride, FFAs and angiotensin II levels were significantly higher in circulating and myocardium in obese rats, associated with lipid deposition, increased mitochondrial cytochrome C release and protein levels of NF-κB and iNOS in myocardium. These alterations were reversed by fenofibrate, in parallel with improvement in +dP/dt, −dP/dt and ultrastructures of myocardial mitochondrion. The cardiac dysfunctions had negative correlation with intramyocardial lipid deposition, FFAs, angiotensin II, and protein levels of NF-κB and iNOS. ConclusionCardiac dysfunction of obese rats could be improved by reducing FFAs level. Intramyocardial lipid accumulation may increase the risk of heart failure in obese rats by increasing renin–angiotensin systems activity and protein levels of NF-κB and iNOS in myocardium.

The plasma 5′-AMP acts as a potential upstream regulator of hyperglycemia in type 2 diabetic mice

Increased plasma free fatty acid (FFA) level is a hallmark of type 2 diabetes. However, the underlying molecular basis for FFA-caused hyperglycemia remains unclear. Here we identified plasma 5'-adenosine monophosphate (pAMP) markedly elevated in the plasma of type 2 diabetic mice. High levels of FFAs induced damage in vein endothelial cells and contributed to an increase in pAMP. Administration of synthetic 5'-AMP caused hyperglycemia and impaired insulin action in lean wild-type mice. 5'-AMP elevated blood glucose in mice deficient in adenosine receptors with equal efficiency as wild-type mice. The function of pAMP was initiated by the elevation of cellular adenosine levels, directly stimulating G-6-Pase enzyme activity, attenuating insulin-dependent GLUT4 translocation in skeletal muscle, and displaying a rapid and steep increase in blood glucose and a decrease in hepatic glycogen level. It was followed by an increase in the gene expression of hepatic Foxo1 and its targeting gene Pepck and G6Pase, which was similar to diabetic phenotype in db/db mice. Our results suggest that pAMP is a potential upstream regulator of hyperglycemia in type 2 diabetes.

Can serum free fatty acids assessment predict severe preeclampsia?

ObjectiveTo estimate the relation between serum free fatty acids (FFAs) and severe preeclampsia in Egypt. MethodsTwenty cases with severe preeclampsia (blood pressure⩾160/110 after 20th week of gestation and proteinuria⩾2.5gm/24h urine) were matched with 20 normotensive pregnant controls for age, and BMI. All study participants were registered to Elshatby Maternity University Hospital within a period of 10months. Evaluation of serum fasting FFAs, uric acid, liver transaminases (AST, ALT) during delivery were done. ResultsThe mean level of FFAs was significantly elevated in preeclampsia cases compared to women with normal blood pressure (2.12±2.64, 0.43±0.29 respectively, p=0.003). Also, cases with high FFAs levels had significant increased levels of serum uric acid than control women with normal blood pressure (6.38±1.25, 5.05±1.85 respectively, p=0.006). Women with high levels of serum FFAs had more than two folds increased risk for neonatal admission to Neonatal Intensive Care Unit OR (2.4). ConclusionThis study suggests that elevated total serum FFAs might be an associated predisposing factor with preeclampsia in non-obese pregnant women.

A Twitchell Reagent Revival: Biodiesel Generation from Low Cost Oils

AbstractThe transesterification of triglycerides with short‐chain alcohols, such as methanol, is the most used process for the obtention of biodiesel. This is a biphasic reaction which can occur both in polar and apolar phases. Using lipophilic sulphonic acids as catalysts, the transesterification reaction takes place primarily in the oil phase. Under these conditions, the reaction rates are considerably improved, with conversions up to 98% in 90 min at 80 °C and with 17.6% mol of catalyst. The most remarkable features of this process are that the catalytic efficiency is not affected by the presence in the oil of free fatty acids or small amounts of water, the transesterification takes place at low temperature (below the boiling point of methanol) and high conversions are reached within a short time. Therefore, low‐cost feedstocks containing high levels of FFA (free fatty acids) and water can be used as raw material for biodiesel production. Finally, catalyst recovery by adsorption on a silica gel column was also tested.

Methanolysis of Jatropha Oil Using Conventional Heating

Studies were carried out on the transesterification, also called methanolysis, of oil from the Jatropha curcas L. with methanol using conventional heating for the production of biodiesel. All reactions were carried out in a batch-stirred reactor and in the subsequent separation and purification stages. The high free-fatty acid (FFA) level of Jatropha oil was reduced to less than 1% by a two-step process. The first step was carried out with 12% w/w methanol-to-oil ratio in the presence of 1% w/w HCl as acid catalyst in a 2h reaction at 343K. The second step was carried out with variable parameters: temperatures at 318K and 333K, initial catalyst concentrations at 0.5% and 1.5%, methanol:oil molar ratios at 4:1 and 6:1, and reaction times at 1h and 2h. Gas chromatography analysis was used to determine the fatty acid profile of crude Jatropha oil. Methanolysis of Jatropha oil used the catalysts NaOH and KOH. The high FFA level of Jatropha oil was reduced from 6.1% to 0.7% after the first step process. The highest yield of fatty acid methyl esters (FAME), however, was achieved at 92.7% in 2h at 4:1 methanol:oil molar ratio, 1.5% w/w KOH, and 333K reaction temperature. This method produced biodiesel that met ASTM’s biodiesel standards. Results showed a density of 0.8g/ml that is within 0.86–0.9kg/l standard range and a kinematic viscosity of about 4.1cSt that is within 2–4.5cSt standard range. The flash point of the biodiesel samples fell between 169oC and 179oC while the cloud point averaged at 6oC.

Effects of metformin on oxidative stress, adenine nucleotides balance, and glucose-induced insulin release impaired by chronic free fatty acids exposure in rat pancreatic islets.

In rat pancreatic islets, chronic exposure to high free fatty acid (FFA) levels impairs insulin secretion and β cell mass. The mechanisms underlying this defect are not completely understood. Since islets have intrinsically low anti-oxidant enzyme defense, oxidative stress might be responsible for β cell damage. In this study, we investigated if FFA could induce oxidative stress in rat pancreatic islets and if metformin might reverse adverse effects. We cultured rat pancreatic islets in the presence or absence of FFA (oleate/palmitate 2:1, 2 mM) for 72 h. In some experiments, we used metformin (2.5 μg/ml) during the last 24 h. In our model, glucosestimu lated insulin release was markedly reduced (p<0.005) after chronic FFA exposure, and the ATP/ADP ratio was altered (p<0.05). We observed a significant increase of reactive oxygen species (ROS) (p<0.001), malondialdehyde a lipid peroxidation product (p<0.01) and nitric oxide (NO) levels in the culture media (p<0.001). Inducible NO synthase (iNOS) and heat shock protein-70 (HSP-70) protein expression were also increased (p<0.001 and p<0.01, respectively). When metformin was present during the last 24 h of culture, insulin secretion was restored, and the ATP/ADP ratio was normalized. ROS production, NO production, lipid peroxidation, iNOS and HSP-70 protein expression levels had decreased. These data indicate that, in rat pancreatic islets, chronic exposure to high FFA induces oxidative stress and that metformin, by reducing this effect, may have a direct beneficial effect on insulin secretion impaired by lipotoxicity.

Association between metabolic abnormalities and HBV related hepatocelluar carcinoma in Chinese: A cross-sectional study

BackgroundPrevious studies suggested that the abnormality of metabolism is a newly identified risk factor in HBV-related hepatocellular carcinoma (HCC). The association between metabolic factors and hepatocellular carcinoma (HCC) has not been clarified up to now. This study was conducted to investigate the prevalence of metabolic abnormalities in HCC and to probe the association between metabolic parameters and liver function as well, so as to evaluate the interactions between metabolism and the development of HBV-related HCC.MethodsTotally 179 cases of HBV-related HCC, who were surgically treated and pathologically confirmed were enrolled. HBV carriers (n = 100) and healthy controls (n = 150) were recruited from routine physical examination during the same period. Body mass index (BMI) was obtained from medical documentation. All the metabolic-related parameters and liver function tests were determined with routine biochemical or immunological analytic methods. Malondialdehyde (MDA) and total antioxidant capacity(TAOC)were detected by chemical analytic methods. A stratified analysis was conducted according to BMI, glycated albumin (GA), free fatty acids (FFA), and the relationships between the metabolic-related parameters and liver functions were analyzed in HCC and control subjects.ResultsHCC group showed significantly high levels of mean BMI, serum glucose, low serum lipids levels than controls (P < 0.05). Acquired by stratified analysis, the higher the BMI, the higher level of insulin and homeostasis model assessment for insulin resistance (HOMA-IR) (P < 0.01) were found in HCC patients. Elevated level of MDA and γ-glutamyltransferase (GGT) were revealed in those with high serum FFA level for the first time. Strong associations between metabolic factors and liver function were shown in HCC (P < 0.05). Higher GA level was strongly associated with increased risk of cancer compared to healthy controls (OR = 9.87, 95% confidence interval: 1.86~52.29). Serum triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) levels were negative contributory factors for HCC (OR = 0.05, 95% confidence interval: 0.01~0.27 and OR = 0.32, 95% confidence interval, 0.11~0.95: respectively).ConclusionsMetabolic abnormalities are closely associated with the occurrence and development of HBV-related HCC. Oxidative stress and/or lipid peroxidation might be involved in the pathogenesis and acceleration of liver function impairments in HCC.

Short-term increase of plasma free fatty acids does not interfere with intrinsic mitochondrial function in healthy young men

Free fatty acid (FFA)- and obesity-induced insulin resistance has been associated with disturbed mitochondrial function. Elevated plasma FFA can impair insulin-induced increase of adenosine triphosphate synthesis and downregulate the expression of genes important in the biogenesis of mitochondria in human skeletal muscle. Whether FAs have a direct effect on intrinsic mitochondrial capacity remains to be established. Therefore, we measured ex vivo mitochondrial respiratory capacity in human skeletal muscle after exposure to hyperinsulinemia and high levels of plasma FFA. Nine healthy lean men were studied during a 6-hour hyperinsulinemic (600 pmol/L) euglycemic clamp with concomitant infusion of Intralipid (Fresensius Kabi Nederland, Den Bosch, the Netherlands) (FFA clamped at 0.5 mmol/L) or saline. Mitochondrial respiratory capacity was measured by high-resolution respirometry in permeabilized muscle fibers using an Oxygraph (OROBOROS Instruments, Innsbruck, Austria). Each participant served as his own control. Peripheral glucose uptake (rate of disappearance) was significantly lower during infusion of the lipid emulsion compared with the control saline infusion (68 μmol/kg·min [saline] vs 40 μmol/kg·min [lipid], P = .008). However, adenosine diphosphate-stimulated and maximal carbonylcyanide-4-(trifluoromethoxy)-phenylhydrazone-stimulated uncoupled respiration rates were not different in permeabilized skeletal muscle fibers after exposure to high levels of FFA compared with the control condition. We conclude that short-term elevation of FFA within the physiological range induces insulin resistance but does not affect intrinsic mitochondrial capacity in skeletal muscle in humans.

Study of Different Priming Treatments on Germination Traits of Soybean Seed Lots

Oilseeds are more susceptible to deterioration due to membrane disruption, high free fatty acid level in seeds and free radical production. These factors are tended to less vigorous seed. Priming treatments have been used to accelerate the germination and seedling growth in most of the crops under normal and stress conditions. For susceptible and low vigor soybean seed, this technique would be a promising method. At first, in separate experiment, effects of hydropriming for (12, 24, 36 and 48 h) with control (none prime) were evaluated on germination traits of soybean seed lots cv. ‘Sari’ (include 2 drying method and 3 harvest moisture). Then, next experiment was conducted to determination the best combination of osmopriming in soybean seed lots, hence 3 osmotic potential level (-8, -10 and -12 bar) at 4 time (12, 24, 36 and 48 h) were compared. Analysis of variance showed that, except for seedling dry weight, the other traits include standard germination, germination rate, seedling length and vigor index were influenced by osmopriming. Hydropriming had no effect on these traits and decreased rate of germination. Finally the best combination of osmopriming were osmotic potential -12 bar at 12 hours for time, that submitted acceptable result in all conditions and recommended for soybean seed lots cv. ‘Sari’.

Changes in the 24 h Rhythmicity of Liver PPARs and Peroxisomal Markers When Feeding Is Restricted to Two Daytime Hours

Restricted feeding (RF) during daytime is associated with anticipatory activity before feeding, marked hyperphagia after mealtime, adjustments in hepatic metabolism, and the expression of a food-entrained oscillator (FEO). 24 h rhythmicity of liver PPARα, β, and γ, peroxisomal markers (PMP70, AOX, and catalase), and free fatty acids (FFAs) during RF was evaluated. The effect of fasting-refeeding was also studied. Results showed (1) higher levels of FFA before feeding, (2) a shift of PPARα and PPARγ before and of PPARβ peaks after feeding, (3) an increase in peroxisomal markers, (4) a shift of PMP70 and AOX peaks before feeding, and of maximal catalase activity in the dark period, (5) changes in the fasting-refeeding response, and (6) high correlations (>0.9) of serum corticosterone with PPARα and PPARγ and of PMP70 with PPARβ. In conclusion, 24 h rhythmicity of FFA, liver PPARs, and peroxisomal markers are biochemical adaptations associated with daytime RF and FEO expression.

Free fatty acids and the metabolic syndrome in patients with obstructive sleep apnoea

Obesity and metabolic syndrome (MS) occur frequently in patients with obstructive sleep apnoea syndrome (OSAS). We hypothesised that circulating free fatty acids (FFAs) are elevated in OSAS patients independently of obesity. This elevation may contribute to the development of MS in these patients. We studied 119 OSAS patients and 119 controls. Participants were recruited and studied at sleep unit of our institution (Hospital Universitari Son Dureta, Palma de Mallorca, Spain) and were matched for sex, age and body mass index (BMI). The occurrence of MS was analysed by clinical criteria. Serum levels of FFAs, glucose, triglycerides, cholesterol, high-density lipoprotein-cholesterol, aspartate aminotransferase, alanine aminotransferase, γ-glutamyltransferase, C-reactive protein and 8-isoprostanes were determined. Prevalence of MS was higher in OSAS than in the control group (38 versus 21%; p=0.006). OSAS patients had higher FFAs levels than controls (mean±sd 12.2±4.9 versus 10.5±5.0 mg·dL(-1); p=0.015). Among subjects without MS, OSAS patients (OSAS+ MS-) showed higher levels of FFAs than controls (OSAS- MS-) (11.6±4.7 versus 10.0±4.4 mg·dL(-1); p=0.04). In a multiple regression model, after adjustment for age, sex, BMI and the presence of MS, FFAs were significantly associated with apnoea/hypopnoea index (p=0.04). This study shows that FFAs are elevated in OSAS and could be one of the mechanisms involved in the metabolic complications of OSAS.

Optimization of factors affecting esterification of mixed oil with high percentage of free fatty acid

Increased environmental awareness and depletion of resources are driving industry to develop alternative fuels from renewable sources that are environmentally more acceptable. Biodiesel is a non petroleum based fuel that consists of alkyl esters from transestrification of the refined/edible types of vegetable oils alcohol and alkaline catalysts can be used. These catalysts require anhydrous conditions and feed stocks with low levels of free fatty acids (FFAs). Inexpensive feed stocks are used in biodiesel production to reduce its cost and to get rid of waste oils in environmentally friendly way. These oils may contain high levels of FFAs so it cannot be directly used with the base catalysts currently employed. Acid esterification reduces the FFAs content to the desirable level. The major factors that affect the conversion efficiency of the process are molar ratio of alcohol/oil, amount of catalyst, reaction temperature, catalyst type and stirring speed according to reaction duration. For this study, we used a model acid produced by mixing pure oleic acid with mixed oil (50% sunflower+50% soybean oil). Methanol was used in the experiments due to its low cost. The best conversion efficiency obtained was 96.6% for a molar ratio of 6:1 at a temperature of 60°C, 2.5% H2SO4 and stirring speed of 300rpm. Finally, different types of waste cooking oil from home and restaurants were used to study the conversion efficiency compared with optimum conditions calculated for model acid oil to be used in biodiesel production with low cost.

Pretransplant Free Fatty Acids (FFA) and Allograft Survival in Renal Transplantation 1

Fatty acids and their eicosanoid metabolites have been shown to be important mediators of the immune response in transplantation. We hypothesize that elevated pretransplant free fatty acids (FFA) levels may be associated with prolonged survival of kidney transplants. Archived pretransplant sera of 130 patients who received a kidney transplant from 1991 to 1997 were analyzed by gas liquid chromatography for a comprehensive FFA profile. FFA levels were categorized by quartiles, and the association between quartiles of the levels for each free-fatty acid and graft survival was initially screened by serial univariate analyses (Kaplan-Meier). All significant variables (FFAs and transplant-specific risk factors) were entered into a multivariable (Cox regression) model. With > 10 y of follow-up, 68 kidney allografts were lost. Factors associated with decreased graft survival by univariate analysis included delayed graft function (DGF), acute rejection (AR), and cold ischemic time (CIT) > 24 h. High levels of arachidonic and γ-linolenic FFA were associated with higher graft survival rates. By multivariate analysis, only DGF, AR, CIT, and arachidonic acid levels were significant. The odds ratios for graft failure for the highest, third, and second quartiles of the pretransplant level of arachidonic acid, compared with the lowest quartile, were 0.18, 0.32, and 0.64, respectively (P = 0.050, log-rank test). For arachidonic acid the survival benefit appeared to be graded with the highest quartile associated with a greater than 80% reduction of risk of kidney graft failure. Pretransplant level of arachidonic acid was independently associated with higher kidney graft survival rates. Further studies are necessary to identify the underlying mechanisms and to determine whether interventions aimed at increasing pretransplant arachidonic acid levels might prove beneficial for renal transplant outcomes.