Influence of dietary partially hydrogenated vegetable and marine oils on membrane composition and function of liver microsomes and platelets in the rat

The aim of the present study was to investigate the influence of partially hydrogenated vegetable and marine oils on membrane composition and function of liver microsomes and platelets with particular reference to the metabolism of linoleic acid and the production of arachidonic acid metabolites. Four groups of male weanling rats were fed linoleic acid supplemented diets containing 20% (w/w) of partially hydrogenated low erucic acid rapeseed oil (HLRSO), partially hydrogenated herring oil (HHO), olive oil (OO) and trierucin + triolein (TE) for 10 weeks. An additional two groups were fed partially hydrogenated low erucic acid rapeseed oil and partially hydrogenated herring oil without linoleic acid supplementation (HLRSO- and HHO-, respectively). Substantial amounts oftrans fatty acids were incorporated into liver microsomes (12.6% in group HLRSO) and platelets (7.0% in group HLRSO-). This incorporation was not dependent on the dietary linoleic acid level. Hepatic microsomal Δ⁵-desaturase activity was significantly increased after HLRSO feeding compared to OO feeding. Δ⁶-Desaturase activity did not vary in the linoleic acid supplemented groups. Both Δ⁵- and Δ⁶-desaturase activities were significantly increased in groups without linoleic acid supplementation. Docosenoic acid was incorporated into platelet phospholipids in contrast to liver microsomes. In the platelet, docosenoic acid seemed to have a special preference for phosphatidylserine. Very small amounts were incorporated into platelet phosphatidylinositol. Feeding diets HLRSO, HHO and OO did not influence rat platelet cyclooxygenase or 12-lipoxygenase activity. Platelets from rats fed TE, however, produced significantly less 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) than platelets from rats fed OO. Feeding of HLRSO- and HHO- resulted in a significantly diminished production of the arachidonic acid metabolites 12-HETE, 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) and 6-keto-prostaglandin F_1α in stimulated platelets and aorta. Thus, high dietary levels oftrans isomers of monoenoic acids do not interfere with platelet cyclooxygenase or lipoxygenase activity provided sufficient amounts of linoleic acid are available.     

Locked nucleic acids and intercalating nucleic acids in the design of easily denaturing nucleic acids: thermal stability studies

Intercalating nucleic acids (INA(R)s) with insertions of (R)-1-O-(1-pyrenylmethyl)glycerol were hybridized with locked nucleic acids (LNAs). INA/LNA duplexes were found to be less stable than the corresponding DNA/LNA duplexes when the INA monomer was inserted as a bulge close to the LNA monomers in the opposite strand. This property was used to make "quenched" complements that possess LNA in hairpins and in duplexes and are consequently more accessible for targeting native DNA. The duplex between a fully modified 13-mer LNA sequence and a complementary INA with six pyrene residues inserted after every second base as a bulge was found to be very unstable (Tm=30.1 degrees C) in comparison with the unmodified double-stranded DNA (Tm=48.7 degrees C) and the corresponding duplexes of LNA/DNA (Tm=81.6 degrees C) and INA/DNA (Tm=66.4 degrees C). A thermal melting experiment of a mixture of an LNA hairpin, with five LNA nucleotides in the stem, and its complementary DNA sequence gave a transition with an extremely low increase in optical density (hyperchromicity). When two INA monomers were inserted into the stem of the LNA hairpin, the same experiment resulted in a significant hyperchromicity comparable with the one obtained for the corresponding DNA/DNA duplex.     

Native Chemical Ligation Directed by Photocleavable Peptide Nucleic Acid (PNA) Templates

A novel peptide–peptide ligation strategy is introduced that has the potential to provide peptide libraries of linearly or branched coupled fragments and will be suited to introduce simultaneous protein modifications at different ligation sites. Ligation is assisted by templating peptide nucleic acid (PNA) strands, and therefore, ligation specificity is solely encoded by the PNA sequence. PNA templating, in general, allows for various kinds of covalent ligation reactions. As a proof of principle, a native chemical ligation strategy was elaborated. This PNA‐templated ligation includes easy on‐resin procedures to couple linkers and PNA to the respective peptides, and a traceless photocleavage of the linker/PNA oligomer after the ligation step. A 4,5‐dimethoxy‐2‐nitrobenzaldehyde‐based linker that allowed the photocleavable linkage of two bio‐oligomers was developed.     

Effect of filler on low temperature physical hardening of bitumen

Laboratory investigations of low temperature physical hardening of bitumen using a Bending Beam Rheometer (BBR) are described. The study encompasses five bitumens, three conditions with regard to additives and three testing temperatures (−15, −25 and −30°C). As additives, two fillers, hydrated lime and calcium carbonate, were used. The effect of the fillers on the isothermal low temperature hardening was evaluated with the aid of a physical hardening index. The viscoelastic nature of the bitumens and bitumen/filler mixtures was investigated utilising the Burger model, and the Burger parameters were used to calculate dissipation energy ratios (dissipated energy over stored energy) in each BBR test. The results obtained did not indicate any significant effect of the fillers on low temperature physical hardening. Analyses of the dissipation energy ratio showed a considerable capacity for energy dissipation, even at a temperature as low as −30°C. With few exceptions, more energy was dissipated than stored during a BBR test. It appears that the dissipation energy ratio is not necessarily related to the stiffness of the binder.     

Studies of arginine-arene interactions through synthesis and evaluation of a series of galectin-binding aromatic lactose esters

Aromatic lactose 2-O-esters were synthesized and used to probe arene-arginine interactions with the galectin family of proteins. They were found to be low microM inhibitors of galectin-1, -3, and -9N-terminal domain and moderate inhibitors of galectin-7, but not inhibitors of galectin-8N-terminal, which lacks an arginine residue close to the critical, esterified lactose 2-O-position. Molecular modeling of galectins in complex with aromatic lactose 2-O-esters, as well as binding studies with a galectin-3 R186S mutant, confirmed that the inhibitory efficiency of the lactose 2-O-esters was due to the formation of strong interactions between the aromatic ester moieties and the arginine guanidinium groups of galectin-1 and -3. An important common feature shared by galectin-1 and -3 was that the arginines formed in-plane ion pairs with two side-chain carboxylates, which resulted in extended planar pi-electron surfaces that did not require solvation by water; these surfaces were ideal for stacking with aromatic moieties of the ligands. The results provide a basis for the design of lectin inhibitors and drugs that exploit interactions with arginine side-chains via aromatic moieties, which are involved in intramolecular protein salt bridges.     

The cyclotide fingerprint in oldenlandia affinis: elucidation of chemically modified, linear and novel macrocyclic peptides

The complete suite of cyclotides present in Oldenlandia affinis (Rubiaceae), the plant that was originally found to contain this unique family of circular proteins, has been characterised. This study expands the number of known cyclotides in this plant to 17, of which nine new sequences (kalata B9-B17) were characterised in this work. In addition, five derivatives that contain oxidation products of the conserved tryptophan were identified, and it was shown that the formation of these derivatives is catalysed by exposure to sunlight. Furthermore, we describe two "linear" cyclotide analogues. These acyclic peptides have three intact disulfide bonds, and their N and C termini coincide with the hypothesised cleavage sites from the precursor protein. This work increases our knowledge about the sequence variation that is accommodated by the cyclic cystine knot scaffold, confirms its applicability as a template for drug design, and also shows the first natural degradation pathways for cyclotides. These pathways have important implications for the persistence and environmental fate of the cyclotides if used as crop-protection agents.     

3-D surface analysis of worn spherical roller thrust bearings

Wear of boundary lubricated spherical roller thrust bearings has been characterised with 3-D surface measurements and analysis. Due to the curved contact surface in a spherical roller thrust bearing, the rollers will undergo sliding in the contact. For an unskewed roller there will be two points along each contact where the sliding velocity is zero. At all other points along the contact, sliding is present. Previously presented results from measurements of the contacting surfaces show that outside the zero sliding points there is a significant change in the washer surface profile due to wear. In order to study how the wear depends on the number of revolutions ten tests were performed. After the tests, 3-D surface roughness measurements were performed. The results from these measurements show that there are different wear mechanisms involved. Initially, the surfaces are run in by possible plastic deformation and two-body abrasion. After running-in, the surfaces are subjected to mild wear probably caused by two-body abrasion and/or delanunation wear. For the long term tests, three-body abrasion clearly influences the amount of wear. A 3-D parameter set was used to characterise the different wear mechanisms. Three amplitude parameters (S_a, S_q S_z) and three of the functional Abbot curve parameters (S_pk, S_k, S_vk) were able to characterise all the wear mechanisms.     

Psychophysiological stress responses, muscle tension, and neck and shoulder pain among supermarket cashiers.

This study examined psychological and physiological stress, as well as muscle tension and musculoskeletal symptoms, among 72 female supermarket cashiers. Stress levels were found to be significantly elevated at work, as reflected in the catecholamines, blood pressure, heart rate, electromyographic (EMG) activity, and self-reports. Fifty cashiers (70%) suffering from neck-shoulder pain (trapezius myalgia) were found to have higher EMG activity at work and reported more tension after work. Women who kept a diary for 1 week and reported more musculoskeletal pain (above the median) were older, had higher blood pressure, and reported more work stress and psychosomatic symptoms. The elevated stress levels at work are consistent with data from workers involved in other types of repetitive tasks and can be important for the high prevalence of neck and shoulder symptoms among the cashiers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)