Short-chain Species Research Articles

Molecular determinants of phospholipid treatment to reduce intracellular cholesterol accumulation in NPC1 deficiency

Niemann-Pick type C (NPC) disease, caused by mutations in the NPC1 or NPC2 genes, leads to abnormal intracellular cholesterol accumulation in late endosomes/lysosomes (LE/LY). Exogenous enrichment with lysobisphosphatidic acid (LBPA), also known as bis-monoacylglycerol phosphate or BMP, either directly or via the LBPA precursor phosphatidylglycerol (PG), has been investigated as a therapeutic intervention to reduce cholesterol accumulation in NPC disease. Here we report the effects of stereoisomer configuration and acyl chain composition of LBPA on cholesterol clearance in NPC1-deficient cells. We find that S,R, S,S, and S,R LBPA stereoisomers behaved similarly, with all 3 compounds leading to comparable reductions in filipin staining in two NPC1-deficient human fibroblast cell lines. Examination of several LBPA molecular species containing one or two mono- or polyunsaturated acyl chains showed that all LBPA species containing one 18:1 chain significantly reduced cholesterol accumulation, whereas the shorter chain species di-14:0 LBPA had little effect on cholesterol clearance in NPC1 deficient cells. Since cholesterol accumulation in NPC1 deficient cells can also be cleared by PG incubation, we used non-hydrolyzable PG analogues to determine whether conversion to LBPA is required for sterol clearance, or whether PG itself is effective. The results showed that non-hydrolyzable PG species were not appreciably converted to LBPA and showed virtually no cholesterol clearance efficacy in NPC1 deficient cells, supporting the notion that LBPA is the active agent promoting LE/LY cholesterol clearance. Overall these studies are helping to define the molecular requirements for potential therapeutic use of LBPA as an option for addressing NPC disease.

Heterogeneous hydrochlorination of lipids mediated by fatty acids in an indoor environment.

Fatty acids from cooking fumes and hypochlorous acid (HOCl) released from indoor cleaning adversely affect respiratory health, but the molecular-level mechanism remains unclear. Here, the effect of cooking oil fumes [palmitic acid (PA), oleic acid (OA), and linoleic acid (LA)] on lung model phospholipid (POPG) hydrochlorination mediated by HOCl at the air-water interface of the hanged droplets was investigated. Interfacial hydrochlorination of POPG was impeded by OA and LA, while that of POPG was facilitated by PA. The effect on POPG hydrochlorination increased with the decrease in oil fume concentration. A potential mechanism with respect to the chain length of these oil fumes, regardless of their saturation, was proposed. PA with a short carbon chain looses the POPG packing and leads to the exposure of the C=C double bonds of POPG, whereas OA and LA with a long carbon chain hinder HOCl from reaching the C=C bonds of POPG. These results for short chain and low concentration dependence suggest that the decay of oil fumes or the conversion of short-chain species by indoor interfacial chemistry might be adverse to lung health. These results provide insights into the relationship between indoor multicomponent pollutants and the respiratory system.

Semiconductor-hydrophobic material interfaces as a new active site paradigm for photocatalytic degradation of perfluorocarboxylic acids

Photocatalytic degradation of long-chain perfluorocarboxylic acid (PFCA) water contaminants has been reported for numerous of semiconductors, including composite TiO2 particles decorated with graphitic carbon co-catalysts. While pristine TiO2 degrades PFCAs inefficiently, the carbon components purportedly enhance activity due to their conductive nature and resultant charge separation enhancement. Yet herein, we present evidence that the catalytic activity of a graphene oxide (GO)-TiO2 composite from the literature arose not due to from charge separation, but to a unique mode of PFCA adsorption occurring at the interface of TiO2 and hydrophobic GO. Photocatalytic degradation rates by GO-TiO2 were compared to those of composites containing nonconductive polymer microparticles (polyethylene, polytetrafluoroethylene). Results showed that polymer-TiO2 composites performed as well as GO-TiO2 in degrading both perfluorooctanoic acid and oxalate, a common hole scavenger. Thus, the enhanced activity may occur for any TiO2-hydrophobic interface, regardless of co-catalyst conductivity. Furthermore, compared to an unmodified reference catalyst, chain length dependence of PFCA degradation by a polymer-TiO2 composite was found to be less severe, with greater activity toward short-chain species indicating enhanced adsorption behavior. Potential adsorption mechanisms are presented, along with broader implications toward improving the applicability of heterogeneous processes toward a wider range of perfluoroalkyl contaminants.

Looking in Depth at Oxidized Cholesteryl Esters by LC-MS/MS: Reporting Specific Fragmentation Fingerprints and Isomer Discrimination.

Cholesteryl esters (CE) are prone to oxidation under increased oxidative stress conditions, but little is known about oxidized CE species (oxCE). To date, only a few oxCE have been identified, however, mainly based on the detection of molecular ions by mass spectrometry (MS) or target approaches for specific oxCE. The study of oxCE occurring from radical oxidation is still scarcely addressed. In this work, we made a comprehensive assessment of oxCE derivatives and their specific fragmentation patterns to identify detailed structural features and isomer differentiation using high-resolution C18 HPLC-MS- and MS/MS-based lipidomic approaches. The LC-MS/MS analysis allowed us to pinpoint oxCE structural isomers of long-chain and short-chain species, eluting at different retention times (tR). Data analysis revealed that oxCE can be modified either in the fatty acyl moiety or in the cholesterol ring. The location of the hydroxy/hydroperoxy group originates characteristic fragment ions, namely the unmodified cholestenyl cation (m/z 369) for the isomer with oxidation in the fatty acyl chain or ions at m/z 367 and m/z 385 (369 + 16) when oxygenation occurs in the cholesterol ring. Additionally, we identified CE 18:2 and 20:4 aldehydic and carboxylic short-chain products that showed a clear fragmentation pattern that confirmed the modification in the fatty acyl chain. Specific fragmentation fingerprinting allowed discrimination of the isobaric short-chain species, namely carboxylic short-chain products, from hydroxy aldehyde short-chain products, with a hydroxycholesterol moiety. This new information is important to identify different oxCE in biological samples and will contribute to unraveling their role in biological conditions and diseases such as cardiovascular disease.

Pathological α-syn aggregation is mediated by glycosphingolipid chain length and the physiological state of α-syn in vivo

GBA1 mutations that encode lysosomal β-glucocerebrosidase (GCase) cause the lysosomal storage disorder Gaucher disease (GD) and are strong risk factors for synucleinopathies, including Parkinson's disease and Lewy body dementia. Only a subset of subjects with GBA1 mutations exhibit neurodegeneration, and the factors that influence neurological phenotypes are unknown. We find that α-synuclein (α-syn) neuropathology induced by GCase depletion depends on neuronal maturity, the physiological state of α-syn, and specific accumulation of long-chain glycosphingolipid (GSL) GCase substrates. Reduced GCase activity does not initiate α-syn aggregation in neonatal mice or immature human midbrain cultures; however, adult mice or mature midbrain cultures that express physiological α-syn oligomers are aggregation prone. Accumulation of long-chain GSLs (≥C22), but not short-chain species, induced α-syn pathology and neurological dysfunction. Selective reduction of long-chain GSLs ameliorated α-syn pathology through lysosomal cathepsins. We identify specific requirements that dictate synuclein pathology in GD models, providing possible explanations for the phenotypic variability in subjects with GCase deficiency.

Dynamics and stress relaxation of bidisperse polymer melts with unentangled and moderately entangled chains

Polydispersity is inevitable in industrially produced polymers. Established theories of polymer dynamics and rheology, however, were mostly built on monodisperse linear polymers. Dynamics of polydisperse polymers is yet to be fully explored—specifically how chains of different lengths affect the dynamics of one another in a mixture. This study explored the dynamics of bidisperse polymer melts using molecular dynamics and a bead–spring chain model. Binary mixtures between a moderately entangled long-chain species and an unentangled or marginally entangled short-chain species were investigated. We found that adding short chains can significantly accelerate the dynamics of the long chains by substantially lessening their extent of entanglement. Meanwhile, although introducing long chains also hinders the motion of the short chains, it does not qualitatively alter the nature of their dynamics—unentangled short chains still follow classical Rouse dynamics even in a matrix containing entangled chains. Detailed Rouse mode analysis was used to reveal the effects of entanglement at chain segments of different scales. Stress relaxation following a step shear strain was also studied, and semi-empirical mixing rules that predict the linear viscoelasticity of polydisperse polymers based on that of monodisperse systems were evaluated with simulation results.

Dam operation altered profiles of per- and polyfluoroalkyl substances in reservoir

Information on the impact of dam operation on per- and polyfluoroalkyl substances (PFASs) distribution in reservoirs is very limited. In the present study, water, riparian soils and floating wastes samples were collected from the Three Gorges Reservoir, China during the storage and the discharge periods to characterize the PFASs distribution. The total PFASs concentrations of water samples in the storage period (50.4−146 ng/L) were 4.7 times higher than those in the discharge period (1.40–38.6 ng/L). The main types of PFASs in water samples changed from PFOA in the discharge period to short-chain species in the storage period. The main analogues in riparian soils and floating wastes were PFOA and PFOS. Wastes contributed little to PFASs mass in the reservoir, while PFASs accumulated in soils accounted for 49.7 % of the total mass when the riparian zone was submerged during the storage period. Changes in profiles of PFASs caused by dam operation suggested that the potential water safety and the shift of riparian soils between source and sink of PFASs may vary with the annual operation cycle of dam. The water resources protection in reservoirs needs strategies that consider the variation of dam operation cycle.

Sulfuric acid-adjuvant sulfonated graphene as efficient polysulfides tamer for high-energy-density Li[sbnd]S batteries

Lithium-sulfur batteries hold great promise for large-scale energy storage owing to their high theoretical energy density and low cost. However, the insulating nature of sulfur and shuttle effect of polysulfides result in low sulfur utilization and rapid capacity decay. Here, sulfonated graphene is fabricated using the low-cost diluted sulfuric acid as sulfonated reagent, for constructing the freestanding sulfur cathode. It is confirmed that the sulfo groups grafted on graphene serve as mediators to react with long-chain polysulfides by forming the thiosulfate/polythionate intermediates, and facilitate the conversion of long-chain polysulfides into short-chain species and solid discharge products. Crucially, the freestanding cathode with sulfur loading of 8.2 mg cm−2 exhibits an areal capacity of 7.57 mA h cm−2 and stable cycling over 100 cycles at 0.1 C.

Omega-3 and omega-6 fatty acid differentially impact cardiolipin remodeling in activated macrophage

BackgroundThe macrophage plays an important role in innate immunity to induce immune responses. Lipid replacement therapy has been shown to change the lipid compositions of mitochondria and potentially becomes an alternative to reduce the inflammatory response.MethodsWe examined the effects of omega-6 arachidonic acid (AA), omega-3 eicosapentaenoic acid (EPA), and omega-3 docosahexaenoic acid (DHA) supplementation on the activated the macrophage cell line RAW264.7 via KdO2-lipid A (KLA). The mitochondrial cardiolipin (CL) and monolysocardiolipin (MLCL) were analyzed by LC-MS.ResultsAfter macrophage activation by KLA, CL shifted to saturated species, but did not affect the quantity of CL. Inhibition of delta 6 desaturase also resulted in the same trend of CL species shift. We further examined the changes in CL and MLCL species induced by polyunsaturated fatty acid supplementation during inflammation. After supplementation of AA, EPA and DHA, the MLCL/CL ratio increased significantly in all treatments. The percentages of the long-chain species highly elevated and those of short-chain species reduced in both CL and MLCL.ConclusionsComparisons of AA, EPA and DHA supplementation revealed that the 20-carbon EPA (20:5) and AA (20:4) triggered higher incorporation and CL remodeling efficiency than 22-carbon DHA (22:6). EPA supplementation not only efficiently extended the chain length of CL but also increased the unsaturation of CL.

Effects of Acute Aerobic Exercise on Acylcarnitine Metabolomics in Skeletal Muscle of Lean vs Overweight/Obese Men

Aerobic exercise improves skeletal muscle mitochondrial function and completeness of fatty acid beta oxidation, which contribute to reductions in lipid accumulation and improved insulin sensitivity. The aim of this study was to determine the acute effects of exercise on the completeness of beta oxidation in lean vs. overweight and obese (Ov/Ob) skeletal muscle. 30 men, aged 19–30 years, were recruited and divided into two groups: lean (BMI<25, 18.5–24.1 kg/m2, n=15) and Ov/Ob (BMI≥25, 25.5–36.9 kg/m2, n=15). Four hours after eating a standardized high‐carbohydrate breakfast (7 kcal/kg; 60% carbohydrate, 25% fat, 15% protein), participants performed an acute bout of cycling exercise (50% VO2max, spending ~650 kcal). Vastus lateralis muscle biopsy samples were collected prior to (Pre) and immediately following (Post) the acute exercise bout. In skeletal muscle, metabolomics of acylcarnitines was determined by tandem MS and data were analyzed using JMP. Pairwise correlation maps were generated for all skeletal muscle acylcarnitines, Pre and Post, in lean and Ov/Ob. Strong (correlation coefficient greater than 0.6) positive correlations were observed between long and medium chain acylcarnitine species in lean Pre and between long and short chain species in lean Post. In Ov/Ob, strong positive correlations were observed among long chain species Pre and between long, medium and short chain species Post. Ov/Ob Pre exhibited a smaller number of positive correlations between long and medium/short chain acylcarnitines compared to lean Pre, indicating more incomplete beta oxidation in Ov/Ob Pre compared to lean Pre. Ov/Ob Post exhibited a higher number of positive correlations between long and medium/short chain fatty acids compared to lean Post, indicating a shift Post exercise to more complete beta oxidation in Ov/Ob Post than in lean Post. Prior to exercise, C2, C10‐OH, C12‐OH, C18:1, C18:2‐OH, C22:4, C22:3 were increased in Ov/Ob compared to lean. Acute exercise resulted in significantly increased levels of short chain acylcarnitnes C2, C3, C4, C5:1, C5, C4‐OH and free carnitine in lean and C2 and C4‐OH in Ov/Ob, with other short chain acylcarnitines tending to increase in Ov/Ob. Medium chain acylcarnitines, C6, C8:1, C7‐DC, C10 and C8‐DC increased in lean Post compared to lean Pre; whereas, C8:1, C7‐DC, C10 and C12 increased in Ob/Ov Post compared to lean Post. There no changes in long chain acylcarnitine levels in lean Post vs. lean Pre; however, C14, C18:1, C20:2, C20:1, C20, C22:3, C22:2 and C22:1 increased in Ov/Ob Post compared to Ov/Ob Pre. Thus, exercise may increase skeletal muscle mitochondrial beta oxidation of fatty acids in both lean and Ov/Ob and may be more effective in increasing completeness of beta oxidation in Ov/Ob.Support or Funding InformationThis research was funded by a Ralph W. and Grace M. Showalter Research Trust grant and Indiana CTSI funds to TMH.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Advancement in Atopic Dermatitis Research Through the Use of a Novel Skin Tape Strip Mass Spectrometry Based Processing Protocol

Allergic skin diseases, including Atopic Dermatitis (AD), severely impair the quality of life of affected patients. AD development is linked to a damaged skin barrier function that can precede clinical AD manifestations by many months. Currently there are no effective tools to predict the development of AD or to characterize the efficacy of applied therapy. Therefore, novel approaches to advance mechanistic understanding of AD as well as clinical management of AD and related skin diseases are needed.We have developed a novel protocol that allows the assessment of skin stratum corneum lipid species and filaggrin breakdown products using minimally invasive tape stripping in combination with liquid chromatography tandem mass spectrometry. Our approach requires only two tape strips to provide quantitative data on multiple lipid species as well as on the degradation products of filaggrin, a major skin protein responsible for skin barrier, pH and moisturizing properties. The hallmark of our approach is in the ability to normalize targeted mass spectrometric data per sample total protein content that was never done before. Our approach also allows to use the same sample for proteomics studies. We have applied our novel protocol to evaluate the difference between lesional and non‐lesional stratum corneum of AD subjects and to compare AD subjects with healthy individuals. The comparison of stratum corneum from 25 healthy adult subjects and 30 AD adult patients using our methodology confirmed previously known information about the shift towards short chain ceramide species in AD lesional skin and also revealed novel factors associated with AD development. Thus, total levels of sphingomyelins, and especially those with short chain fatty acids, were found to be increased several fold in atopic lesional skin. Furthermore, lysophosphatidylcholines demonstrated a profound redistribution towards the prevalence of short chain species not only in lesional but also in non‐lesional skin of AD subjects. These novel findings suggest a global shift in fatty acid biosynthesis that might be triggered by hyperactivated type 2 immune response. In fact, the RNAseq analysis performed on stratum corneum from same subjects revealed the downregulation of expression of fatty acid elongases ELOVL3 and ELOVL6 that may explain the observed global redistribution of the long chain and short chain lipids. Furthermore, the modeling of the effect of type 2 cytokines on sphingolipids using human differentiated keratinocytes in vitro confirmed the ability of type 2 cytokines IL‐4 and IL‐13 to provoke similar changes in sphingolipids. Our current ongoing studies further validate the power of the developed methodology and the value of lysophosphatidylcholines as biomarkers of atopic disease.In conclusion, skin tape stripping in conjunction with our unique processing protocol and targeted mass spectrometric methodology opens novel possibilities in clinical research by unveiling novel biomarkers of skin diseases and by allowing clinical studies in the skin using minimally invasive methodology.Support or Funding InformationNIH/NIAID grant U19 AI117673, NIH/NIAMS grant R01 AR41256This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Cutis laxa, exocrine pancreatic insufficiency and altered cellular metabolomics as additional symptoms in a new patient with ATP6AP1-CDG

Congenital disorders of glycosylation (CDG) are genetic defects in the glycoconjugate biosynthesis. >100 types of CDG are known, most of them cause multi-organ diseases. Here we describe a boy whose leading symptoms comprise cutis laxa, pancreatic insufficiency and hepatosplenomegaly. Whole exome sequencing identified the novel hemizygous mutation c.542T>G (p.L181R) in the X-linked ATP6AP1, an accessory protein of the mammalian vacuolar H+-ATPase, which led to a general N-glycosylation deficiency. Studies of serum N-glycans revealed reduction of complex sialylated and appearance of truncated diantennary structures. Proliferation of the patient's fibroblasts was significantly reduced and doubling time prolonged. Additionally, there were alterations in the fibroblasts' amino acid levels and the acylcarnitine composition. Especially, short-chain species were reduced, whereas several medium- to long-chain acylcarnitines (C14-OH to C18) were elevated. Investigation of the main lipid classes revealed that total cholesterol was significantly enriched in the patient's fibroblasts at the expense of phophatidylcholine and phosphatidylethanolamine. Within the minor lipid species, hexosylceramide was reduced, while its immediate precursor ceramide was increased. Since catalase activity and ACOX3 expression in peroxisomes were reduced, we assume an ATP6AP1-dependent impact on the β-oxidation of fatty acids. These results help to understand the complex clinical characteristics of this new patient.

Evidence for a gas-flaring source of alkanes leading to elevated ozone in air above West Africa

As part of the African Monsoon Multidisciplinary Analysis (AMMA) project, the FAAM BAe-146 research aircraft sampled the lower and mid-troposphere around the West Africa sub-region. Back trajectory analysis of the air parcels sampled on-board during the entire duration of the flights showed the history and fate of the air parcels. Data from flights B228 and B231 showed strongly enhanced carbon monoxide (CO) and ozone levels attributable to emissions of anthropogenic origin from the city of Lagos and gas flaring activities in the Nigeria oil fields. The elevated levels of ozone and CO observed at about 6 km above the sea-level on flight B231 were attributed to long-range transport of biomass burning plume from the East, around Sudan. The strongly enhanced mixing ratios of short-chained alkanes and CO (> 400 ppbv) observed from measurements on flights B228 and B231 are indicative of natural gas/combustion sources. Flight B222 sampled air parcels strongly impacted by emissions from Lagos but not from the Nigeria oil field and measured relatively lower mixing ratios of ozone, CO and short-chained alkanes species. Results from this study strongly suggests gas flaring emissions in the Niger Delta area to be a prominent contributor to the enhanced levels of short-chained alkane species observed in Lagos metropolis, especially during the West Africa Monsoon (WAM) months and, hence, a significant source of atmospheric aerosol in the sub-region. Key words: African Monsoon Multidisciplinary Analysis (AMMA), gas flaring, West Africa Monsoon, alkanes, ozone, Niger Delta.

Molecular dynamics study on the role of hydroxyl groups in heat conduction in liquid alcohols

On the basis of non-equilibrium molecular dynamics (NEMD) simulation for alcohols from ethanol to tetracosanol, the present study analyzes the molecular-level energy transfer in associated liquids for the first time. Direct evaluation of the energy transfer by each interatomic interaction reveals a counterintuitive result that in liquid alcohols the Coulomb interaction does not transfer heat more than the van der Waals interaction even for short chain species like ethanol. In addition, by comparing the NEMD analysis on alcohols with those of alkanes, we discuss a molecular mechanism by which alcohol has a higher thermal conductivity than alkane in view of molecular heat transfer. It is shown that hydroxyl OH, not only provides heat paths for the Coulomb interaction, but also increases the number of heat paths for the vdW and the intramolecular interactions. Consequently, the part of the heat transfer by the vdW interaction is replaced with more efficient transfers by the Coulomb and intramolecular interactions, and therefore a higher thermal conductivity occurs. The insights obtained from the present study update the view of microscopic heat transfer in associated liquid towards the molecular theory of thermal conductivity of liquids, which is currently immature in comparison with those of gases and solids.

Residual organic fluorinated compounds from thermal treatment of PFOA, PFHxA and PFOS adsorbed onto granular activated carbon (GAC)

Perfluorooctanoic acid (PFOA), perfluorohexanoic acid (PFHxA) and perfluorooctane sulfonate (PFOS) adsorbed onto granular activated carbon (GAC) were thermally treated in N2 gas stream. The purpose was to assess the fate of perfluoroalkyl and polyfluoroalkyl substances (PFASs) during thermal regeneration of GAC, which had been used for water treatment. Mineralized F, residual PFASs including short-chained species, and volatile organic fluorine (VOF) were determined. In a temperature condition of 700 °C, VOF were 13.2, 4.8, and 5.9 % as for PFOA, PFHxA, and PFOS. However, the VOF decreased to 0.1 %, if the GAC and off-gas were kept at 1000 °C. No PFASs remained in GAC at 700–1000 °C; at the same time, short-chained PFASs were slightly detected in the aqueous trapping of off-gas at 800 and 900 °C conditions. The destruction of PFASs on GAC could be perfect if the temperature is higher than 700 °C; however, the process is competitive against volatile escape from GAC. Destruction in gaseous phase needs a temperature as high as 1000 °C. Destruction of PFASs on the surface of GAC, volatile escape from the site, and thermolysis in gas phase should be considered, as to thermal regeneration of GAC.

Understanding and Controlling of Solution Chemistry of Lithium Polysulfide to Enable High Energy Li-S Redox Flow Battery

Large-scale energy storage has become an important topic for the modern life. The identification of high energy and low cost energy storage and conversion technologies for stationary applications has gained intensive research interest in recent years. Lithium sulfur (Li-S) redox flow battery is one of the most promising candidates. Fundamental understanding and controlling of polysulfide chemistry were explored to enable high energy Li-S redox flow cells. Different from static Li-S batteries targeting for vehicle electrification, high solubility of all lithium polysulfide generated at different depth of discharge and state of charge is preferred in flow battery in order to take full advantage of multiple electron transitions between S and Li2S. A new kind of DMSO based electrolyte was first proposed for Li-S redox flow batteries, which not only enable high solubility lithium polysulfide species, especially for the short-chain species, but also stabilize excellent cycling with high Coulombic efficiency. Challenges and opportunities existing in the Li-S redox flow concept have also been discussed in detail.

Effects of Molecular Size and Surface Hydrophobicity on Oligonucleotide Interfacial Dynamics

Single-molecule total internal reflection fluorescence microscopy was used to observe the dynamic behavior of polycytosine single-stranded DNA (ssDNA) (1-50 nucleotides long) at the interface between aqueous solution and hydrophilic (oligoethylene glycol-modified fused silica, OEG) and hydrophobic (octadecyltriethoxysilane-modified fused silica, OTES) solid surfaces. High throughput molecular tracking was used to determine >75,000 molecular trajectories for each molecular length, which were then used to calculate surface residence time and squared displacement (i.e., "step-size") distributions. On hydrophilic OEG surfaces, the surface residence time increased systematically with ssDNA chain length, as expected due to increasing molecule-surface interactions. Interestingly, the residence time decreased with increasing ssDNA length on the hydrophobic OTES surface, particularly for longer chains. Similarly, the interfacial mobility of polynucleotides slowed with increasing chain length on OEG, but became faster on OTES. On OTES surfaces, the rates associated with desorption and surface diffusion exhibited the distinctive anomalous temperature dependence that is characteristic of hydrophobic interactions for short-chain species but not for longer chains. These combined observations suggest that long oligonucleotides adopt conformations minimizing hydrophobic interactions, e.g., by internal sequestration of hydrophobic nucleobases.

Bioenergetic Metabolites in the Diabetic Peripheral Nervous System (IN1-1.007)

Objective: To quantify changes in steady-state intermediary metabolites of glycolysis, TCA cycle and fatty acid beta-oxidation in sciatic nerve (SCN) from type 2 diabetic mice, providing a link between peripheral nerve-specific metabolic abnormalities and the development of diabetic neuropathy (DN). Background DN affects approximately 60% of diabetic patients and is characterized by the progressive loss of peripheral axons, resulting in pain and eventual loss of sensation. DN is the leading cause of diabetes-related hospital admissions and nontraumatic amputations in the US. Despite the morbidity associated with DN, the fundamental biological abnormalities that are most critical to DN progression remain unclear. There is a prevailing view that hyperglycemia and hyperlipidemia are associated with increased flux through these respective pathways in the diabetic peripheral nerve, but no definitive evidence exists to support this hypothesis. An understanding of diabetic metabolic abnormalities distinct to the peripheral nerve may be crucial to developing effective treatments for DN. Design/Methods: The BLKS-db/db murine model of type 2 diabetes develops severe DN, with dyslipidemia and hyperglycemia. Targeted mass-spectrometry was used to quantify alterations in glycolytic, TCA cycle and beta-oxidation intermediates in BLKS-db/db mouse SCN. Results: Metabolic profiling demonstrated reduced long-chain acyl-CoAs, carnitine and short-chain acyl-carnitine species, along with decreases in glycolytic, TCA cycle and adenosine phosphate energy intermediates, in 24-week db/db (diabetic) compared with db/+ (control) SCN. Conclusions: Our data reveal a novel metabolic profile in diabetic SCN. These data challenge the theory that excessive metabolism through glycolysis and beta-oxidation is implicit in the development of diabetic complications, including DN. Further identification of this diabetic metabolic signature critical for DN progression will be useful in the diagnosis and therapeutic management of patients. Supported by: NIH 1 R24 DK082841-01, NIH 1 UO1 DK076160, NIH 1RC 1NS068182, NIH DK089503, The A. Alfred Taubman Institute and The Program for Neurology Research and Discovery. Disclosure: Dr. Hinder has nothing to disclose. Dr. Buller has nothing to disclose. Dr. Pennathur has nothing to disclose. Dr. Feldman has received personal compensation for activities with Novartis.

Oxidation and formation of oxidation products of β-carotene at boiling temperature

β-Carotene is one of the most important lipid component extensively used in food industries as source of pro-vitamin A and colorant. During processing and storage β-carotene is oxidized and degraded to various oxidation compounds. Some of these compounds are also the key aroma compounds in certain flowers, vegetables and fruits. The methods for analysis and determination of these oxidized products formed during food boiling or preparation are key to the understanding the chemistry of these compounds. This paper presents a novel analytical method incorporating high performance liquid chromatography with diode array and mass spectrometric detection for the characterization of oxidation, isomerization and oxidation products of β-carotene in toluene at boiling temperature. HPLC and APCI–MS was optimized using oxidized sample and flow injection analysis of the standard β-carotene respectively. β-Carotene was oxidized in the Rancimat at 110°C for 30, 60 and 90min. The oxidized samples were than analyzed by HPLC system at 450nm and 350nm as well as scanning and single ion monitoring mass spectrometry. A total of ten oxidation products and three Z-isomers were reported. Extensive isomerization was observed during treatment at the control accelerated conditions. The oxidation products include five apo-carotenals, three diepoxides, one mono-epoxide and one short chain species. Results show that the method was reproducible, accurate and reliable for the separation and identification of oxidation products of β-carotene.

Hydrogen Peroxide-Induced Oxidation of Mixtures of Alkanethiols and Their Quantitative Detection as Alkanesulfonates by Electrospray Ionization Mass Spectrometry

Finding optimal experimental conditions for generating stable negative ion electrospray ionization ion trap mass spectra (ESI-IT-MS) of alkanethiol-derived species is critical for quantitatively characterizing multicomponent alkanethiol-based self-assembled monolayers by this technique. Since alkanethiolates slowly oxidize in solution, purposeful oxidation of alkanethiols to their fully oxidized form (alkanesulfonates) is advantageous: sulfonates are chemically stable and have little affinity for covalent binding to metal surfaces. We have used ESI-IT-MS to characterize the products of H(2)O(2) oxidation of simple n-alkanethiols in solution and have observed monomeric alkanesulfonate species as well as alkanesulfonic acid/alkanesulfonate adducts, yielding gas-phase dimers and trimers. MS intensities of both monomers and adducts exhibit a dependence on the ion transfer capillary temperature that is alkyl-chain-length-dependent and that appears to be correlated with C-S bond cleavage. The trend in optimal capillary temperatures indicates that entropic effects lead to lower thermal decomposition temperatures for short-chain species relative to the longer-chain homologues. MS calibration data from alkanesulfonate mixtures are characterized by large linear dynamic ranges (10(-6)-10(-3) M) and detection limits influenced by their thermal decomposition. The high degree of precision in the calibration data should facilitate distinguishing among mixed SAMs having similar compositions.