Postprandial metabolism of docosapentaenoic acid (DPA, 22:5n−3) and eicosapentaenoic acid (EPA, 20:5n−3) in humans

The study of the metabolism of docosapentaenoic acid (DPA, 22:5n?3) in humans has been limited by the unavailability of pure DPA and the fact that DPA is found in combination with eicosapentaenoic acid (EPA, 20:5n?3) and docosahexaenoic acid (DHA, 22:6n?3) in natural products. In this double blind cross over study, pure DPA and EPA were incorporated in meals served to healthy female volunteers. Mass spectrometric methods were used to study the chylomicron lipidomics. Plasma chylomicronemia was significantly reduced after the meal containing DPA compared with the meal containing EPA or olive oil only. Both EPA and DPA were incorporated into chylomicron TAGs, while there was less incorporation into chylomicron phospholipids. Lipidomic analysis of the chylomicron TAGs revealed the dynamic nature of chylomicron TAGs. The main TAG species that EPA and DPA were incorporated into were EPA/18:1/18:1, DPA/18:1/16:0 and DPA/18:1/18:1. There was very limited conversion of DPA and EPA to DHA and there were no increases in EPA levels during the 5 h postprandial period after the DPA meal. In conclusion, EPA and DPA showed different metabolic fates, and DPA hindered the digestion, ingestion or incorporation into chylomicrons of the olive oil present in the meal.     

Computational investigation of the geometric structures of [(CN)5PtTl(CN)n]n− (n=0, 1, 2 or 3)

[(CN)₅PtTl(CN)_n]ⁿ⁻ (n=0–3, complexes I–IV) have been studied computationally using quasi-relativistic gradient-corrected density functional theory. Good agreement is obtained with previous EXAFS and Raman data for complexes II–IV, but calculations significantly overestimate the PtTl bond length and underestimate ν(PtTl) for complex I. The addition of co-ordinating water molecules to the thallium atom in complexes I–III has little effect on complexes II and III, but significantly shortens the PtTl bond in complex I, bringing it into excellent agreement with experiment. The bond length shortening is traced to intramolecular hydrogen bonding. The total molecular bonding energies of hydrated I and I′ (in which the axial ligands on the thallium and platinum atoms are interchanged) are found to be very similar to one another, suggesting that complex I might exist as a mixture of isomers in solution.     

Diverse effects of essential (n−6 andn−3) fatty acids on cultured cells

Fatty acids (FAs) have long been recognized for their nutritional value in the absence of glucose, and as necessary components of cell membranes. However, FAs have other effects on cells that may be less familiar. Polyunsaturated FAs of dietary origin (n–6 andn–3) cannot be synthesized by mammals, and are termed essential because they are required for the optimal biologic function of specialized cells and tissues. However, they do not appear to be necessary for normal growth and metabolism of a variety of cells in culture. The essential fatty acids (EFAs) have received increased attention in recent years due to their presumed involvement in cardiovascular disorders and in cancers of the breast, pancreas, colon and prostate. Manyin vitro systems have emerged which either examine the role of EFAs in human disease directly, or utilize EFAs to mimic thein vivo cellular environment. The effects of EFAs on cells are both direct and indirect. As components of membrane phospholipids, and due to their varying structural and physical properties, EFAs can alter membrane fluidity, at least in the local environment, and affect any process that is mediated via the membrane. EFAs containing 20 carbons and at least three double bonds can be enzymatically converted to eicosanoid hormones, which play important roles in a variety of physiological and pathological processes. Alternatively, EFAs released into cells from phospholipids can act as second messengers that activate protein kinase C. Furthermore, susceptibility to oxidative damage increases with the degree of unsaturation, a complication that merits consideration because lipid peroxidation can lead to a variety of substances with toxic and mutagenic properties. The effects of EFAs on cultured cells are illustrated using the responses of normal and tumor human mammary epithelial cells. A thorough evaluation of EFA effects on commercially important cells could be used to advantage in the biotechnology industry by identifying EFA supplements that lead to improved cell growth and/or productivity.Abbreviations AA arachidonic acid (20 carbons: 4 double bonds,n–6) - BHA butylated hydroxyanisole - BHT butylated hydroxytoluene - cAMP cyclic adenosine monophosphate - CHO Chinese hamster ovary - DAG diacylglycerol - DGLNA dihomo--linolenic acid (203,n–6) - DHA docosahexaenoic acid (226,n–3) - EFA essential fatty acid - EGF epidermal growth factor - EGFR epidermal growth factor receptor - EPA eicosapentaenoic acid (205,n–3) - FA fatty acid - FBS fetal bovine serum - GLNA -linolenic acid (183,n–6) - LA linoleic acid (182,n–6) - LNA -linolenic acid (183,n–3) - LT leukotriene - MDA malondialdehyde - NAD nicotinamide adenine dinucleotide - NDGA nordihydroguaiaretic acid - OA oleic acid (181,n–9) - PG prostaglandin - PKC protein kinase C - PUFA polyunsaturated fatty acid - SFM serum-free medium - TX thromboxane     

Excited state relaxation in Cr(CN)6−n(H2O)nn−3 complexes

The emission spectra and excited state decay rates have been recorded for Cr(CN)_6−n(H₂O)_nⁿ⁻³ (n = 0-6) complexes. Both the transition energy and relaxation rates increase with n but the large changes in transition energies are not sufficient to account for the failure of the displaced coordinate to explain the relaxation rate results.     

Identification of Primula “front-end” desaturases with distinct n−6 or n−3 substrate preferences

cDNA clones encoding cytochrome b₅ fusion desaturases were isolated from Primula cortusoides L. and Primula luteola Ruprecht, species previously shown to preferentially accumulate either n−6 or n−3 Δ6-desaturated fatty acids, respectively. Functional characterisation of these desaturases in yeast revealed that the recombinant Primula enzymes displayed substrate preferences, resulting in the predominant synthesis of either γ-linolenic acid (n−6) or stearidonic acid (n−3). Independent expression of the two Primula desaturases in transgenic Arabidopsis thaliana confirmed these results, with γ-linolenic acid and stearidonic acid accumulating in both leaf and seed tissues to different levels, depending on the substrate specificity of the desaturase. Targeted lipid analysis of transgenic Arabidopsis lines revealed the presence of Δ6-desaturated fatty acids in the acyl-CoA pools of leaf but not seed tissue. The implications for the transgenic synthesis of C₂₀ polyunsaturated fatty acids via the elongation of Δ6-desaturated fatty acids are discussed, as is the potential of using Primula desaturases in the synthesis of C₁₈ n−3 polyunsaturated fatty acids such as stearidonic acid.     

Probing the electronic structures and properties of neutral and anionic ScSi n (0,−1) (n = 1–6) clusters using ccCA-TM and G4 theory

We apply molecular docking, molecular dynamics (MD) simulation, and binding free energy calculation to investigate and reveal the binding mechanism between five xanthine inhibitors and DPP-4. The electrostatic and van der Waals interactions of the five inhibitors with DPP-4 are analyzed and discussed. The computed binding free energies using MM-PBSA method are in qualitatively agreement with experimental inhibitory potency of five inhibitors. The hydrogen bonds of inhibitors with Ser630 and Asp663 can stabilize the inhibitors in binding sites. The van der Waals interactions, especially the key contacts with His740, Asn710, Trp629, and Tyr666 have larger contributions to the binding free energy and play important roles in distinguishing the variant bioactivity of five inhibitors.     

Selective isolation of highly polymorphic (dC−dA)n · (dG−dT)n microsatellites by stringent hybridization

We defined a hybridization condition for isolation of clones carrying long (dC−dA)_n · (dG−dT)_n microsatellites from a genomic plasmid library. By using (dC−dA)₂₀ oligonucleotide as a probe and hybridizing under stringent conditions, more than two-thirds of the obtained plasmid carried the repeats that were longer than (dC−dA)₁₄ and higly polymorphic.     

Synthesis of polypyrrole within the cell wall of yeast by redox-cycling of [Fe(CN)6]3−/[Fe(CN)6]4−

Yeast cells are often used as a model system in various experiments. Moreover, due to their high metabolic activity, yeast cells have a potential to be applied as elements in the design of biofuel cells and biosensors. However a wider application of yeast cells in electrochemical systems is limited due to high electric resistance of their cell wall. In order to reduce this problem we have polymerized conducting polymer polypyrrole (Ppy) directly in the cell wall and/or within periplasmic membrane. In this research the formation of Ppy was induced by [Fe(CN)₆]³⁻ions, which were generated from K₄[Fe(CN)₆], which was initially added to polymerization solution. The redox process was catalyzed by oxido-reductases, which are present in the plasma membrane of yeast cells. The formation of Ppy was confirmed by spectrophotometry and atomic force microscopy. It was confirmed that the conducting polymer polypyrrole was formed within periplasmic space and/or within the cell wall of yeast cells, which were incubated in solution containing pyrrole, glucose and [Fe(CN)₆]⁴⁻. After 24 h drying at room temperature we have observed that Ppy-modified yeast cell walls retained their initial spherical form. In contrast to Ppy-modified cells, the walls of unmodified yeast have wrinkled after 24 h drying. The viability of yeast cells in the presence of different pyrrole concentrations has been evaluated.     

Application of the Criterion of Biological Time (τ n /τ0) to the Studies of Embryogenesis in Birds

It was shown on the example of chick embryo that the number ₀ ( _n /₀) can be recommended as a measure of biological time and, for this purpose, the duration of the minimal mitotic cycle during synchronous cleavage divisions should be determined (in minutes) in various avian species. Based on the preliminary data, one can propose the comparability and similarity of the temporal programs of gastrulation and somitogenesis in the chick embryo and embryos of some fish and amphibians.     

Microsolvation and hydration enthalpies of CaC2O4(H2O) n (n = 0-16) and C2O4 2-(H2O) n (n = 0-14): an ab initio study

We studied hydrated calcium oxalate and its ions at the restricted Hartree–Fock RHF/6-31G* level of theory. Performing a configurational search seems to improve the fit of the HF/6-31G* level to experimental data. The first solvation shell of calcium oxalate contains 13 water molecules, while the first solvation shell of oxalate ion is formed by 14 water molecules. The first solvation shell of Ca(II) is formed by six water molecules, while the second shell contains five. At 298.15 K, we estimate the asymptotic limits (infinite dilution) of the total standard enthalpies of hydration for Ca(II), oxalate ion and calcium oxalate as ?480.78, –302.78 and –312.73 kcal mol^?1, resp. The dissociation of hydrated calcium oxalate is an endothermic process with an asymptotic limit of +470.84 kcal mol^?1.

First-principles study on the structures and electronic properties of graphene-supported Nin (n = 1–6) clusters

ABSTRACT

The structural and electronic properties, such as adsorption energy, magnetic property, and charge-transferring process of Ni_n (n?=?1–6) clusters interacting with pristine, strained and defective graphene were investigated by using the density functional theory calculations with the Perdew–Burke–Ernzerhof exchange-correlation energy functional. By introducing strain and defects, the stability of the cluster-graphene system was improved significantly. The magnetic moments increased monotonically for Ni_n clusters on pristine and strained graphene while exhibited an oscillating behaviour for defective graphene. On the other hand, more charges being transferred from Ni_n clusters to defective graphene were observed compared with pristine and strained graphene.     

Ground state intermolecular proton transfer in the supersystems thymine–(H2O)n and thymine–(CH3OH)n, n = 1,2: a theoretical study

Twelve binary and eight ternary supersystems between thymine and methanol, and water were investigated in the ground state at the B3LYP and MP2 levels of theory using B3LYP/6-311 + + G(d,p) basis functions. The thermodynamics of complex formations and the mechanisms of intermolecular proton transfers were clarified in order to find out the most stable H-boned system. It was established that the energy barriers of the water/methanol-assisted proton transfers are several times lower than those of the intramolecular proton transfers in the DNA/RNA bases. The X-ray powder spectra of thymine, and this precrystallized from water and methanol showed that water molecules are incorporated in the crystal lattice of thymine forming H-bridges between thymine molecules. Figure Intermolecular H-bonding of thymine     

n−3 polyunsaturated fatty acids modulate metabolism of insulin-sensitive tissues: implication for the prevention of type 2 diabetes

Obesity is frequently associated with the development of type 2 diabetes which is firstly characterized by a defect in the response of key metabolic tissues to insulin (insulin resistance). The imbalance in fatty composition of the diet, a low-grade inflammatory state have been described to be involved in the initiation or the amplification of the molecular events involved in this process. The concept of a specific nutritional intervention has emerged as a promising tool against metabolic disorders associated with obesity. In this context, many investigations were conducted to evaluate the potential beneficial impacts of n?3 polyunsaturated fatty acids (n?3 PUFA). The aim of the present review was to summarize the current knowledge about the role of docosahexanoic acid (DHA, 22:6n?3) and eicosapentanoic acid (EPA, 20:5n?3) on key metabolic organs. Only studies aiming to understand the mechanism of actions were selected. The analysis of randomized clinical trial about n?3 PUFA was not considered here. The effects of n?3 PUFA were analyzed in the adipose tissue, the liver, skeletal muscle and the pancreas in the context of obesity and lipid oversupply. Furthermore, in line with recent findings about the role of the modulation of gut microbiota in obesity-related disorders, we summarized the recent findings about the possible link between n?3 PUFA and change in microbiota composition.     

Changes in fluidity and 22:6(n − 3) content in phospholipids of trout intestinal brush-border membrane as related to environmental salinity

Phospholipids and fatty acids analyses were carried out on brush-border membranes isolated from trout intestine. Phosphatidylcholine (PC) is the principal phospholipid of these membranes. When animals are transferred from fresh water to sea water, the content of the 22:6(n ? 3) fatty acid strongly increases at the level of phospholipids, mainly PC. Concomitantly, an important increase in the fluidity of the lipid core of the membrane was detected by steady-state fluorescence anisotropy. It is suggested that the molecular species of PC (especially rich in n ? 3 fatty acids) may have an important part to play in marine organisms according to the osmoregulation problems met in these animals.     

Absorption of DNA in the region of vacuum-uv (3–25 eV)

By means of a device that might be considered a modern version of "Ulbricht's sphere" the absorption spectrum and the photoelectric emission of calf thymus DNA was measured in the region of 3 to 25 eV (400 to 50 nm). A tentative explanation of the general shape of the absorption spectrum and of its 6 maxima is given. The results permit a much better insight into some biologic effects of vacuum-uv to be gained than hitherto possible.     

Large gallanes and the PSEPT theory: a theoretical study of Ga n H n+2 clusters (n?=?7–9)

Do alanes Al(n)H(n+2) and gallanes Ga(n)H(n+2) satisfy the polyhedral skeletal electron pair theory (PSEPT)? Taking into account previous work on this question, this paper provides a convincing answer and proposes the reformulation of the (n + 1) electron pairs rule of Wade and Mingos (W-M) for such systems. Following recent studies of tetra-, penta-, hexa-, hepta-, octa-, and nonaalanes as well as valence-isoelectronic/related gallanes, in this paper we present an analysis of the hydrides of aluminum and gallium A(n)H(n+2) (A = Al, Ga and n = 7-9). The aim is still to examine the applicability of PSEPT, especially the W-M rule, to these clusters. Exploration of the total potential energy surfaces (PESs) of hepta-, octa-, and nonagallanes shows that the absolute minima have a nido-like polyhedron arrangement. Unlike the smaller Ga(n)H(n+2) (n = 4, 5, 6), it seems that the size of the cluster largely dictates its preferred geometry. Although none of them have closed (totally triangular) cages, these clusters exhibit significant compactness, comparable to borane double anions, B(n)H(n) (2-), which are the archetypes for the PSEPT theory.     

Review of the marsupials (Mammalia: Metatheria) from the late Paleogene (Chadronian–Arikareean: late Eocene–late Oligocene) of North America

The taxonomy of marsupials from the late Paleogene of North America (Chadronian to Arikareean North American land mammal ages: late Eocene–late Oligocene) is reviewed based on new and previously undescribed fossil material as well as reevaluation of previously described material. Two families are recognized, the Herpetotheriidae and Peradectidae. Nine species of herpetotheriids are recognized within two genera: Herpetotherium Cope, 1873a and Copedelphys Korth, 1994, including one new species, H. tabrumi. The greatest diversity of herpetotheriids was in the Chadronian (four species). By the late Arikareean, only a single species is recognized. The range of Copedelphys is extended into the early Whitneyan (previously limited to Chadronian–Orellan). Among species of Herpetotherium, the ranges of two species have been extended: H. valens (Lambe, 1908) from the Chadronian is reported from the Orellan, and H. marsupium (Troxell, 1923) from the Uintan and Duchesnean is reported from the early Chadronian. The range of H. merriami (Stock and Furlong, 1922), previously only known from the Arikareean of Oregon, is expanded geographically eastward to Montana. Within the Peradectidae only three species are recognized: Peradectes cf. californicus (Stock, 1936) and Didelphidectes pumilis Hough, 1961 from the Chadronian, and Nanodelphys hunti (Cope, 1873b) from the Orellan to early Arikareean. Specimens previously identified as an unnamed new species of Nanodelphys from the Whitneyan and Arikareean are referred here to N. hunti.