Cell Membrane Fatty Acid Research Articles

Effect of environmental stress on cell surface and membrane fatty acids of Lactobacillus plantarum.

Adhesion has been regarded as one of the basic features of probiotics. We undertake this study in the aim to give new insight about the change in cellular physiological state under heat and acid treatments of Lactobacillus plantarum. Different cell properties have been investigated such as adhesive ability to abiotic surfaces, the cell surface hydrophobicity and the fatty acids profiles. The results of cell surface properties and Gas chromatography analysis demonstrated a modification in term adhesive ability and fatty acid (FA) composition of the tested strain under stressful conditions. In fact, after the exposure of the strain to heat and acid treatments, an increase in the hydrophobicity level and the adhesion capacity on HeLa cells was shown. Our findings revealed that high temperature and low pH change the fatty acids profiles of the treated cells, especially the proportions of unsaturated and saturated fatty acid. In this context, our data revealed that the unsaturated FA-to-saturated FA ratio was increased significantly (P<0.05) for stressed strains compared with control cells. The results of the present finding suggest that the tested strain have suffered changes like the modifications on bacterial membrane as a cellular response to survive the hard environmental conditions, allowing them to withstand harsh conditions and sudden environmental changes to survive under.

Flow cytometry and capillary electrophoresis analyses in ethanol-stressed Oenococcus oeni strains and changes assessment of membrane fatty acid composition.

This study aimed to investigate the dynamics and physiological heterogeneity of Oenococcus oeni under different conditions, cell membrane fluidity and permeability variations, and assessment of changes in cell surface charging rates. Flow cytometry, membrane fatty acid analysis and capillary electrophoresis were performed to study ethanol-induced variations. Different physiological states were assessed, revealing cell subpopulations able to adapt and withstand to environmental stress, in order to recover their functionality. Moreover, total results demonstrated changes in cell surface and membrane fatty acid redistribution with a saturation degree and an unsaturated/saturated fatty acid ratio fairly steady in control and in different ethanol stresses. This study revealed a great variability among O. oeni strains and the importance to investigate the mechanisms by a multiparametric approach based on the structural and physiological bacterial adjustments in different stresses tolerance. Intermediate physiological state assessment in O. oeni with recovery possibility could be an important criterion for potential starter culture application. The flow cytometry application with changes in monitoring membrane fatty acid composition and in surface charging rates allowed the characterization of sorted subpopulations that may contribute to further understanding of diversity and heterogeneity in physiology of bacterial populations.

Cell Membrane Fatty Acid Composition of Chryseobacterium frigidisoli PB4T, Isolated from Antarctic Glacier Forefield Soils, in Response to Changing Temperature and pH Conditions.

Microorganisms in Antarctic glacier forefields are directly exposed to the hostile environment of their habitat characterized by extremely low temperatures and changing geochemical conditions. To survive under those stress conditions microorganisms adapt, among others, their cell membrane fatty acid inventory. However, only little is known about the adaptation potential of microorganisms from Antarctic soil environments. In this study, we examined the adaptation of the cell membrane polar lipid fatty acid inventory of Chryseobacterium frigidisoli PB4T in response to changing temperature (0°C to 20°C) and pH (5.5 to 8.5) regimes, because this new strain isolated from an Antarctic glacier forefield showed specific adaptation mechanisms during its detailed physiological characterization. Flavobacteriaceae including Chryseobacterium species occur frequently in extreme habitats such as ice-free oases in Antarctica. C. frigidisoli shows a complex restructuring of membrane derived fatty acids in response to different stress levels. Thus, from 20°C to 10°C a change from less iso-C15:0 to more iso-C17:1ω7 is observed. Below 10°C temperature adaptation is regulated by a constant increase of anteiso-FAs and decrease of iso-FAs. An anteiso- and bis-unsaturated fatty acid, anteiso-heptadeca-9,13-dienoic acid, shows a continuous increase with decreasing cultivation temperatures underlining the particular importance of this fatty acid for temperature adaptation in C. frigidisoli. Concerning adaptation to changing pH conditions, most of the dominant fatty acids reveal constant relative proportions around neutral pH (pH 6–8). Strong variations are mainly observed at the pH extremes (pH 5.5 and 8.5). At high pH short chain saturated iso- and anteiso-FAs increase while longer chain unsaturated iso- and anteiso-FAs decrease. At low pH the opposite trend is observed. The study shows a complex interplay of different membrane components and provides, therefore, deep insights into adaptation strategies of microorganisms from extreme habitats to changing environmental conditions.

Evaluation of dietary intake and red blood cell membrane fatty acid profile on the incidence of metabolic syndrome in Hispanic children from 2 to 10 years of age

Metabolic syndrome (MetS) is a grouping of criteria including hypertension, glucose intolerance, truncal obesity/high BMI, insulin resistance, increased VLDL, high triglycerides (TAG), and low HDL. MetS is a problem in Hispanic children due to increasing obesity rates and a predisposition for insulin resistance.MethodsHispanic children aged 2 to 10 years of age were evaluated during a well child visit and data including demographic information, food frequency questionnaire, anthropometric measures, and blood samples were collected. Children were considered “at risk” for this study if they exhibited 3 or more risk factors for developing MetS. Risk factors included abdominal obesity, elevated blood pressure, elevated triglycerides, low HDL and/or elevated plasma glucose concentrations. A total of 112 children were included in this analysis with 33 (~29%) in the “at risk” category. Statistical analysis was via SPSS 22 multivariate General Linear Model evaluating differences between “normal” and “at risk” children.Results“At risk” children had higher serum levels for total cholesterol (159.4 vs 146.5 mg/dL, p=0.010), VLDL (32.4 vs 20.5 mg/dL, p=0.0001), LDL (82.9 vs 74.9 mg/dL, p=0.074), Cholesterol/HDL ratio (3.73 vs 2.98, p=0.0001), Triglycerides (161.4 vs 103.0 mg/dL, p=0.0001), and had lower levels for HDL (44.2 vs 51.0 mg/dL, p=0.002). Ferric Reducing Ability of Plasma (FRAP) was higher for “at risk” children (0.416 vs 0.349, p=0.017) but results may have been influenced by plasma uric acid. FFQ results (Block Kids Screener) indicated that dietary saturated fat (p=0.070), meat, poultry, fish, (p=0.146), protein (p=0.067), total fat (p=0.058), carbohydrates (p=0.032), fiber (p=0.003), kcal (p=0.042) and glycemic load (p=0.049) were lower for “at risk” children; they also tended to consume less food. Red blood cell membrane fatty acid profile revealed no significant differences for membrane saturated, MUFA, PUFA, n‐3 or n‐6 fatty acids.ConclusionIndicators of fat metabolism show that children with higher levels of lipid serum markers are at risk for developing metabolic syndrome. The relationship between red blood cell membrane fatty acid profile and dietary intake do not completely explain why certain Hispanic children are “at risk” for developing MetS.Support or Funding InformationResearch supported by Tennessee Board of Regents Diversity Grant and several Small Research Development Committee Grants from East Tennessee State University's Office of Research and Sponsored Programs.

Effect of PFOA on Oxidative Stress and Membrane Damage of Escherichia coli

Perfluorooctanoic acid (PFOA) is widely used in industrial production because of its strong chemical stabilities and good hydrophobic and oleophobic properties. It was considered to be a widespread persistent organic pollutant in environment in recent years. The oxidative stress and membrane damage of Escherichia coli exposed to PFOA were measured by flow cytometry (FCM) and the toxic mechanism of PFOA was also preliminarily explored. The results showed that, under the stress of PFOA, the intracellular reactive oxygen species (ROS) content of E. coli increased, the unsaturation degree of fatty acid decreased, the malondialdehyde (MDA) content increased, the membrane permeability increased, the membrane potential decreased, and the activities of Na+K+-ATPase and Ca2+Mg2+-ATPase showed a compensatory increase first and then decreased. Therefore, owing to the stress of PFOA, the higher intracellular ROS in E. coli reacted with membrane unsaturated fatty acids by peroxidation,and then reduced cell membrane fatty acid saturation, accumulated MDA in cells, and further caused damage to cell membrane, reduced the ATPase activity, and eventually resulted in inactivation or apoptosis of E. coli. This study provided more evidence for the further study on environmental ecological toxicology of PFOA.

Carbohydrate quality and quantity affects the composition of the red blood cell fatty acid membrane in overweight and obese individuals

Cell membrane fatty acid (FA) composition may play a role in human metabolic diseases. However, the modulatory effect of nutrients other than fat is poorly explored. To investigate the effect of moderate-carbohydrate diets with different glycemic indices (GI) and a low-fat diet (LF) on red blood cell (RBC) FA membrane composition. The RBC FA profile was measured in 87 subjects from the GLYNDIET study. Participants were randomly assigned to one of the following energy-restricted diet for 6 months: moderate-carbohydrate/low-GI diet (LGI, n=31), moderate-carbohydrate/high-GI diet (HGI, n=30) or LF-diet (n=26). We observed a significant increase in C20:0 and decrease in C20:3n-6 in the LGI and HGI groups compared to LF group. Compared to LF-diet, C22:4n-6 was lower after the HGI while C22:6n-3 was higher after LGI diet. Also, a tendency was found for higher concentrations of long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) in LGI compared to HGI and LF groups. The intra-group analysis showed significantly increased levels of total monounsaturated fatty acids (MUFA) after LGI and HGI interventions, as well as a significant increase in C22:5n-6 and a decrease in LCn-3PUFA and omega-3-index after the LF diet. The decrease in C20:5n-3 after HGI and LF diets was also significant. Diets with a moderate amount of carbohydrates and healthy fat, mainly with LGI, modify the RBC fatty acid membrane composition.

EPRS is a critical mTORC1-S6K1 effector that influences adiposity in mice.

Metabolic pathways contributing to adiposity and aging are activated by the mammalian target of rapamycin complex 1 (mTORC1) and p70 ribosomal protein S6 kinase 1 (S6K1) axis1–3. However, known mTORC1-S6K1 targets do not account for observed loss-of-function phenotypes, suggesting additional downstream effectors4–6. Here we identify glutamyl-prolyl tRNA synthetase (EPRS) as an mTORC1-S6K1 target that contributes importantly to adiposity and aging. EPRS phosphorylation at Ser999 by mTORC1-S6K1 induces its release from the aminoacyl tRNA multisynthetase complex (MSC), required for execution of noncanonical functions beyond protein synthesis7,8. To investigate physiological function of EPRS phosphorylation, we generated EPRS knock-in mice bearing phospho-deficient Ser999-to-Ala (S999A) and phospho-mimetic (S999D) mutations. Homozygous S999A mice exhibited low body weight, reduced adipose tissue mass, and increased lifespan, thereby displaying notable similarities with S6K1-deficient mice9–11 and mice with adipocyte-specific deficiency of raptor, an mTORC1 constituent12. Substitution of the EPRS S999D allele in S6K1-deficient mice normalized body mass and adiposity, indicating EPRS phosphorylation mediates S6K1-dependent metabolic responses. In adipocytes, insulin stimulated S6K1-dependent EPRS phosphorylation and release from the MSC. Interaction screening revealed phospho-EPRS binds Slc27a1 (i.e., fatty acid transport protein 1, FATP1)13–15, inducing its translocation to the plasma membrane and long-chain fatty acid uptake. Thus, EPRS and FATP1 are terminal mTORC1-S6K1 axis effectors critical for metabolic phenotypes.

Role of a combination of myrtle extract and fish oil supplementation in improving endothelial dysfunction in streptozotocin-induced diabetic rats

Background/aim Diabetes mellitus is one of the most important systemic diseases in the world and considered as the leading cause of endothelial dysfunction. Our previous studies have been clarified the antioxidant, anti-inflammatory, and antidiabetic effects of myrtle extract and fish oil. This study aimed to explore the effect of supplementation of a combination of myrtle extract and fish oil in improving the endothelial dysfunction associated with diabetes. Materials and methods Sixty albino rats were classified into three groups (20 rats each): control group, diabetic group, and treated diabetic group that received myrtle extract and fish oil. Plasma 5-lipoxygenase (5-LOX), interleukin-1β, tumor necrosis factor α, lipoxin-A4, asymmetric dimethylarginine, nitric oxide, glucose, insulin, insulin resistance, and cell membrane fatty acids [arachidonic acid (ω-6), linoleic acid (ω-6), α-linolenic acid (ω-3), and oleic acid (ω-9)] were estimated. Results Using a combination of myrtle extract and fish oil induced significant decrease in the plasma level of 5-lipoxygenase, asymmetric dimethylarginine, arachidonic acid (ω-6), linoleic acid (ω-60), and glucose, whereas induced significant increase in lipoxin-A4, nitric oxide, and α-linolenic acid (ω-3). Conclusion A combination of myrtle extract and fish oil has a potential effect that exceed the beneficial role of each of them in reducing endothelial dysfunction as well as oxidative stress and inflammation associated with diabetes mellitus.

A Prospective Analysis of Erythrocyte Membrane Fatty Acid Concentrations and Risk of Non-Hodgkin Lymphoma

Introduction: Circulating fatty acids, which can serve as biomarkers of diet or activity of specific metabolic pathways, may influence non-Hodgkin lymphoma (NHL) risk by modulating inflammation or lymphocyte membrane stability. We performed prospective studies to evaluate red blood cell (RBC) membrane fatty acids as biomarkers of future NHL risk, hypothesizing a positive association for RBC saturated and trans fatty acids and an inverse association for polyunsaturated fatty acids (PUFAs) with risk of NHL and major NHL subtypes.Methods: We conducted a nested case-control study among Nurses' Health Study (NHS) and Health Professionals Follow-up Study (HPFS) participants who provided blood samples in 1989-90 (NHS) or 1993-4 (HPFS). We confirmed 583 incident NHL cases through 2010 and matched one control per case on age, gender, race, and blood draw date. By gas chromatography we identified and determined membrane concentrations of 33 individual fatty acids in RBCs. We estimated the odds ratio (OR) and 95% confidence interval (CI) of NHL per 1 standard deviation (SD) increase in RBC level of specific fatty acids using unconditional logistic regression adjusted for matching factors. We also analyzed three common B-NHL subtypes individually (chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma) and examined all B-NHLs in aggregate with and without CLL/SLL.Results: We observed no associations between specific fatty acids and NHL risk overall (data not shown). In subtype-specific analyses, RBC very long chain saturated fatty acid (VLCSFA) levels (including the 20:0, 22:0, 23:0 fatty acids) were inversely associated with the group of all B-NHLs except CLL/SLL, with ORs suggesting 18% to 19% decreases in risk per SD increase in concentration (Table 1). We observed suggestive inverse associations of similar magnitude for follicular lymphoma and DLBCL but no clear association with CLL/SLL for these 3 VLCSFAs (Table 1). These three VLCSFAs had moderate to strong pairwise correlations; Spearman correlations were 0.61 for 20:0 with 22:0, 0.42 for 20:0 with 23:0 and 0.64 for 22:0 with 23:0. PUFAs were also inversely associated with all B-NHL except CLL/SLL, a finding primarily driven by RBC arachidonic acid levels [OR (95%CI) per SD: 0.83 (0.71, 0.90)] and suggestive also for follicular lymphoma [OR, 95% CI per SD: 0.79 (0.61, 1.02)] and DLBCL [OR, 95% CI per SD: 0.82 (0.64, 1.06)]. The remaining RBC fatty acids, including trans fatty acids, had no clear association with any NHL endpoint (data not shown). We did not observe heterogeneity by follow-up interval or age, although we had limited statistical power to detect significant heterogeneity for specific NHL subtypes.Conclusion: RBC levels of VLCSFAs and PUFAs may be associated with lower risk of several types of B-NHL other than CLL/SLL. The specific fatty acids found to be related with NHL risk are not good biomarkers of diet, suggesting that the observed relations may instead be due to endogenous metabolic processes. Investigation is warranted into biologic mechanisms by which circulating fatty acids and their determinants may influence NHL risk, as is further examination of these associations in larger (ideally pooled) study populations. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Dietary α-linolenic acid supplementation alters skeletal muscle plasma membrane lipid composition, sarcolemmal FAT/CD36 abundance, and palmitate transport rates

The cellular processes influenced by consuming polyunsaturated fatty acids remains poorly defined. Within skeletal muscle, a rate-limiting step in fatty acid oxidation is the movement of lipids across the sarcolemmal membrane, and therefore, we aimed to determine the effects of consuming flaxseed oil high in α-linolenic acid (ALA), on plasma membrane lipid composition and the capacity to transport palmitate. Rats fed a diet supplemented with ALA (10%) displayed marked increases in omega-3 polyunsaturated fatty acids (PUFAs) within whole muscle and sarcolemmal membranes (approximately five-fold), at the apparent expense of arachidonic acid (-50%). These changes coincided with increased sarcolemmal palmitate transport rates (+20%), plasma membrane fatty acid translocase (FAT/CD36; +20%) abundance, skeletal muscle triacylglycerol content (approximately twofold), and rates of whole body fat oxidation (~50%). The redistribution of FAT/CD36 to the plasma membrane could not be explained by increased phosphorylation of signaling pathways implicated in regulating FAT/CD36 trafficking events (i.e., phosphorylation of ERK1/2, CaMKII, AMPK, and Akt), suggesting the increased n-3 PUFA composition of the plasma membrane influenced FAT/CD36 accumulation. Altogether, the present data provide evidence that a diet supplemented with ALA increases the transport of lipids into resting skeletal muscle in conjunction with increased sarcolemmal n-3 PUFA and FAT/CD36 contents.

The Free Radical Diseases of Newborn

Free radicals (FRs) are unstable, short lived, and highly reactive molecules that are continuously generated by endogenous and exogenous mechanisms. The burden of FR generation is counteracted by the intracellular antioxidant systems, and the maintenance of oxidant/antioxidant balance is critical to normal cellular functions. The dangerous effects of FRs are linked to their property of being very unstable molecules and their ability to react with polyunsaturated fatty acids of cell membranes, proteins, polysaccharides, nucleic acids, causing functional alterations within the cell. In neonatal period, hypoxia, ischemia, ischemia-reperfusion, hyperoxia, inflammation, mitochondrial impairment, presence of nonprotein bound iron are responsible of excessive FRs production. Moreover, a less efficient antioxidant system is not able to counteract the harmful effects of FRs leading to FR-related cellular, tissue, and organ damages. In preterm babies, the severity of mechanisms responsible of FRs production, the stage at which the oxidative insult occurs, the degree of maturity of the organs have differential effects on the distinct cell populations of the body, with certain specific cell types being particularly vulnerable in perinatal period. We propose the hypothesis that oxidative stress (OS) is the common pathogenic factor involved in the onset and develop of intraventricular hemorrhage, periventricular leukomalacia, retinopathy of prematurity, bronchopulmonary dysplasia, and necrotizing enterocolitis. This suggests that developing effective antioxidant strategies for preterm infants requires a detailed understanding of oxidative stress reactions and cell responses in perinatal period.

Influence of perfluorooctanoic acid on proteomic expression and cell membrane fatty acid of Escherichia coli

Perfluorooctanoic acid (PFOA) has received an increasing attention in the agricultural and food industries due to its risk to human health. To facilitate the development of novel biomarkers of Escherichia coli against PFOA through multi-omics technologies, and to reveal the resistance mechanism of E. coli against PFOA at protein levels, the interactions among pollutant stress, protein expression and cell metabolism was investigated by using iTRAQ-based quantitative proteomic analysis. The results revealed that the 63 up-regulated proteins mainly involved in tricarboxylic acid cycle, glyoxylate and dicarboxylate metabolism and fatty acid biosynthesis, whereas, the 69 down-regulated proteins related to oxidative phosphorylation, pyruvate metabolism and the cell cycle-caulobacter pathway, were also associated with the increase of membrane permeability, excessive expenditure of ATP, disruption of fatty acid biosynthesis under PFOA stress. The results provide novel insights into the influence mechanisms of PFOA on fatty acid and protein networks.

Effect of cell membrane fatty acid composition of Escherichia coli on the resistance to pulsed electric field (PEF) treatment

The underlying relationships between growth temperature, membrane fatty acid composition (mFAC) and PEF resistance of Escherichia coli (E. coli) were explored. Results indicated the PEF resistance of E. coli at stationary stage was directly related to mFAC. For the cells at stationary stage, as growth temperature decreased from 37 °C to 15 °C, the PEF (23.3 kV/cm, 1.2 ms) lethality of E. coli was increased 1.5 log10, reached 3.2 log10. Meanwhile, the proportion of unsaturated fatty acid (UFA) was increased from 20.07 to 47.65%. And the fluidity index (FI) of the cell membrane was also increased from 0.42 to 1.42. It revealed that the PEF resistance of E. coli at stationary stage was determined by the mFAC and fluidity of the cell membrane. Those conclusions were also confirmed by cytomembrane fluidity determined by fluorescence probe (DPH) and the different PEF-induced electro-permeabilization of dioleoyl-sn-glycero-3-phosphocholine (DOPC) and Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) vesicles. On the other hand, for the cell at exponential stage, the PEF resistance of E. coli was rarely affected by mFAC. The PEF (23.3 kV/cm, 1.2 ms) lethality of cells was almost the same (3.2 log10) at different growth temperature.

Protective role of glutathione addition against wine-related stress in Oenococcus oeni

Oenococcus oeni is the main species responsible for the malolactic fermentation (MLF) of wine due to its ability to survive in this environment. Some wine-related stress factors, such as ethanol and low pH, may alter the cell redox balance of O. oeni. For the first time, the ability to uptake glutathione (GSH), an almost universal tripeptide with antioxidant properties, has been associated to the improvement of stress response in O. oeni. Despite the inability of O. oeni to synthesize GSH, this bacterium can capture it from the media. The ability of 30 O. oeni strains to uptake GSH was assessed in this study. Although all of the strains tested were able to import GSH, substantial variability among them was detected. To assess the physiological function of GSH, three strains with different GSH-import capacities were selected. Significant changes in membrane fatty acids composition were observed due to GSH addition. The most relevant was the increase of cyclopropane fatty acids in cell membrane, in both the exponential and the stationary phases. Cells grown with GSH showed an improved survival against ethanol shock (14% v/v). GSH addition also increased biomass production during the adaptation to wine stress conditions (pH4, pH3.4 and 6% ethanol). The results suggest that GSH enrichment could improve the resistance to stress to O. oeni, which could be useful for the adaptation of MLF starter cultures.

Fatty acid profiling of blood cell membranes by gas chromatography with mass spectrometry.

Fatty acids, which are well-known for their influence on human metabolism and signal transduction, are also a substantial component of cellular membranes and regulate the basic properties and functions of membranes. Owing to their multiple functions, fatty acid profiles of cell membranes are of great interest to those who are studying the relationship between membrane biochemical compositions and functions. A HCl-catalyzed derivation method and a gas chromatography with mass spectrometry analysis method were developed to accurately profile the fatty acids in cell membranes of erythrocytes, leukocytes, and platelets. The detection limits of all 35 fatty acids ranged from 0.58 to 22 ng/mL and the limits of quantitation were between 2.1 and 72 ng/mL. Finally, the established method was used to profile the membrane fatty acids of 44 healthy volunteers from the north and south of China. Results revealed significant differences in the fatty acid profiles from the two regions, particularly those of the erythrocytes. This technique may be applied to cell membrane studies to generate new biological hypotheses concerning fatty acid composition and membrane functions as well as to construct related disease profiles.

Prediction of transition from ultra-high risk to first-episode psychosis using a probabilistic model combining history, clinical assessment and fatty-acid biomarkers.

Current criteria identifying patients with ultra-high risk of psychosis (UHR) have low specificity, and less than one-third of UHR cases experience transition to psychosis within 3 years of initial assessment. We explored whether a Bayesian probabilistic multimodal model, combining baseline historical and clinical risk factors with biomarkers (oxidative stress, cell membrane fatty acids, resting quantitative electroencephalography (qEEG)), could improve this specificity. We analyzed data of a UHR cohort (n=40) with a 1-year transition rate of 28%. Positive and negative likelihood ratios were calculated for predictor variables with statistically significant receiver operating characteristic curves (ROCs), which excluded oxidative stress markers and qEEG parameters as significant predictors of transition. We clustered significant variables into historical (history of drug use), clinical (Positive and Negative Symptoms Scale positive, negative and general scores and Global Assessment of Function) and biomarker (total omega-3, nervonic acid) groups, and calculated the post-test probability of transition for each group and for group combinations using the odds ratio form of Bayes' rule. Combination of the three variable groups vastly improved the specificity of prediction (area under ROC=0.919, sensitivity=72.73%, specificity=96.43%). In this sample, our model identified over 70% of UHR patients who transitioned within 1 year, compared with 28% identified by standard UHR criteria. The model classified 77% of cases as very high or low risk (P>0.9, <0.1) based on history and clinical assessment, suggesting that a staged approach could be most efficient, reserving fatty-acid markers for 23% of cases remaining at intermediate probability following bedside interview.

Acid Response of Bifidobacterium longum subsp. longum BBMN68 Is Accompanied by Modification of the Cell Membrane Fatty Acid Composition.

The acid response of Bifidobacterium longum subsp. longum BBMN68 has been studied in our previous study. The fab gene, which is supposed to be involved in membrane fatty acid biosynthesis, was demonstrated to be induced in acid response. In order to investigate the relationship between acid response and cell membrane fatty acid composition, the acid adaptation of BBMN68 was assessed and the membrane fatty acid composition at different adaptation conditions was identified. Indeed, the fatty acid composition was influenced by acid adaptation. Our results showed that the effective acid adaptations were accompanied with decrease in the unsaturated to saturated fatty acids ratio (UFA/SFA) and increase in cyclopropane fatty acid (CFA) content, which corresponded to previous studies. Moreover, both effective and non-effective acid adaptation conditions resulted in decrease in the C18:1 cis-9/C18:1 trans-9 ratio, indicating that the C18:1 cis-9/C18:1 trans-9 ratio is associated with acid tolerance response but not with acid adaptation response. Taken together, this study indicated that the UFA/SFA and CFA content of BBMN68 were involved in acid adaptation and the C18:1 cis-9/C18:1 trans-9 ratio was involved in acid tolerance response.

The Bioeffects Resulting from Prokaryotic Cells and Yeast Being Exposed to an 18 GHz Electromagnetic Field.

The mechanisms by which various biological effects are triggered by exposure to an electromagnetic field are not fully understood and have been the subject of debate. Here, the effects of exposing typical representatives of the major microbial taxa to an 18 GHz microwave electromagnetic field (EMF)were studied. It appeared that the EMF exposure induced cell permeabilisation in all of the bacteria and yeast studied, while the cells remained viable (94% throughout the exposure), independent of the differences in cell membrane fatty acid and phospholipid composition. The resulting cell permeabilisation was confirmed by detection of the uptake of propidium iodine and 23 nm fluorescent silica nanospheres using transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Upon EMF exposure, the bacterial cell membranes are believed to become permeable through quasi-endocytosis processes. The dosimetry analysis revealed that the EMF threshold level required to induce the uptake of the large (46 nm) nanopsheres was between three and six EMF doses, with a specific absorption rate (SAR) of 3 kW/kg and 5 kW/kg per exposure, respectively, depending on the bacterial taxa being studied. It is suggested that the taxonomic affiliation and lipid composition (e.g. the presence of phosphatidyl-glycerol and/or pentadecanoic fatty acid) may affect the extent of uptake of the large nanospheres (46 nm). Multiple 18 GHz EMF exposures over a one-hour period induced periodic anomalous increases in the cell growth behavior of two Staphylococcus aureus strains, namely ATCC 25923 and CIP 65.8T.

Red blood cell membrane fatty acid composition in infants fed formulas with different lipid profiles

BackgroundThere is growing interest in the fatty acid composition of breast milk and substitute formulas used to replace or complement infant breastfeeding. AimThe aims of this study were to assess the impact of two follow-up infant formulas based on cow milk fat, vegetable oils and different docosahexaenoic (DHA) and arachidonic (ARA) acid content on red blood cell membrane fatty acid composition, and determine the percent saturated fatty acid (SFA) incorporation into the membrane. Study designThis was a double-blind, randomized, controlled, parallel-group clinical trial. Infants received treatment or control product for at least four months before the age of six months. The control group (n=25) received standard infant formula (FA) and the treatment group (n=24) received the same formula supplemented with higher DHA and ARA content (FB). The reference group (n=47) consisted of normal healthy exclusively breastfed infants. Outcome measureRed blood cell membrane fatty acid composition was determined by capillary gas chromatography. ResultsNinety-six infants completed the study (FA, 25; FB, 24; reference, 47). Higher DHA content reflected higher DHA percentage in the red blood cell membrane. Breast milk and FB did not show any significant differences in DHA content. ARA percentage was higher in breastfed infants and palmitic acid percentage was higher in FB- compared with FA-fed infants. ConclusionDHA and palmitic acid percent distributions were higher in the red blood cell membrane of infants receiving FB. DHA percent distribution was not significantly different in FB-fed and breastfed infants. SFA percent distribution was not significantly different when comparing both formulas with breast milk.

Dietary fat and insulin resistance: a connection through leptin and PPARγ activation

Insulin resistance refers to reduced insulin action in peripheral tissues and impaired suppression of endogenous glucose production, a state which is critical for maintaining normal glucose homeostasis. Insulin resistance is partly explained by genetic factors and is strongly influenced by the individual's habitual lifestyle. Investigating factors that may influence the development of insulin resistance and their mechanisms of action is of huge importance; one such factor is the dietary fat. Both quantitative and qualitative terms of dietary fat have been known to play an important role in the development of insulin resistance, though the mechanism underlying this effect is not fully understood. In this regard, the classical view has been that dietary fat quality mainly affects cell membrane fatty acid composition and consequently the membrane function. Recently, the relationship between dietary fat and insulin resistance has entered an advanced level by the discovery that different fatty acids can regulate gene expression, transcriptional activity and adipocytokines secretion. In essence, this provides new mechanisms by which fatty acids exert their cellular effects. The present review critically assesses the effect of dietary fat quality on the development of insulin resistance in relation to the adipocytokine, leptin and the activation of the transcription factor, peroxisome proliferator-activated receptor gamma (PPARγ). It is evident that fat quality influences the development of insulin resistance and has more important role than quantity. Leptin and PPARγ prove to be potential candidates linking dietary fat with insulin resistance. However, the exact role or mechanism of action of various types of dietary fat in the development of insulin resistance is still uncertain. Further well-controlled studies in humans are needed to be able to establish better evidence-based dietary fat recommendations for diabetes prevention and its clinical management. Keywords: dietary fat, insulin resistance, diabetes, PPARγ activation, leptin.