Effect of dietary alpha-linolenic acid and its ratio to linoleic acid on platelet and plasma fatty acids and thrombogenesis

The effect of dietary alpha-linolenic acid (18:3n-3) and its ratio to linoleic acid (18:2n-6) on platelet and plasma phospholipid (PL) fatty acid patterns and prostanoid production were studied in normolipidemic men. The study consisted of two 42-d phases. Each was divided into a 6-d pre-experimental period, during which a mixed fat diet was fed, and two-18 d experimental periods, during which a mixture of sunflower and olive oil [low 18:3n-3 content, high 18:2/18:3 ratio (LO-HI diet)], soybean oil (intermediate 18:3n-3 content, intermediate 18:2/18:3 ratio), canola oil (intermediate 18:3n-3 content, low 18:2/18:3 ratio) and a mixture of sunflower, olive and flax oil [high 18:3n-3 content, low 18:2/18:3 ratio (HI-LO diet)] provided 77% of the fat (26% of the energy) in the diet. The 18:3n-3 content and the 18:2/18:3 ratio of the experimental diets were: 0.8%, 27.4; 6.5%, 6.9; 6.6%, 3.0; and 13.4%, 2.7, respectively. There were appreciable differences in the fatty acid composition of platelet and plasma PLs. Nevertheless, 18:1n-9, 18:2n-6 and 18:3n-3 levels in PL reflected the fatty acid composition of the diets, although very little 18:3n-3 was incorporated into PL. Both the level of 18:3n-3 in the diet and the 18:2/18:3 ratio were important in influencing the levels of longer chain n-3 fatty acid, especially 20:5n-3, in platelet and plasma PL. Production of 6-keto-PGF1 alpha was significantly (P < 0.05) higher following the HI-LO diet than the LO-HI diet although dietary fat source had no effect on bleeding time or thromboxane B2 production.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of myosin heavy chain isoform expression and postmortem metabolism on the ATPase activity of muscle fibers

The objective of this study was to determine the effects of postmortem muscle pH and temperature declines on the actomyosin ATPase activity of muscle fibers expressing different MyHC isoforms. Using a quantitative histochemical procedure to determine ATPase activity, the maximum actomyosin ATPase activity was determined on individual fibers classified by MyHC expression. Samples were collected from the red (RST) and white (WST) semitendinosus muscles at 3 min and 24 h postmortem from electrically stimulated (ES) and control (NS) pork carcasses. In samples taken at 3 min postmortem, type I fibers had the lowest ATPase activity staining and type 2X and 2B had the highest activity staining, with type 2A fibers intermediate. Postmortem time and carcass treatment did not influence the ATPase activity staining of type I muscle fibers. ATPase activity staining of 2A fibers was lower (p<0.001) in 24 h samples than in 3 min samples from ES carcasses. In 3 min and NS-24 h samples, RST type 2A fibers had lower (p<0.05) activities than type 2A fibers from the WST. In type 2X fibers, ATPase activity staining decreased (p<0.01) from 3 min to 24 h postmortem in ES carcasses. This decrease was more severe in WST 2X fibers compared to RST 2X fibers. ATPase activity staining in type 2B fibers did not decrease from 3 min to 24 h postmortem in NS carcasses. In ES carcasses, activity staining of 2B fibers decreased (p<0.0001) with time postmortem. The results of the experiment indicate that fibers expressing fast MyHC isoforms have a higher ATPase activity early postmortem than slow muscle fibers but are more prone to inactivation by a rapid pH decline.     

Low-Temperature Treatment of Transformation-Toughened Partially Stabilized Magnesia-Doped Zirconia–A Solid Particle Erosion Study

It is now well established that the mechanical behavior of transformation-toughened partially stabilized zirconias (PSZs) is controlled by R -curve effects arising from the martensitic transformations. Recent studies have induced the martensitic transformation via a liquid-nitrogen-cooling treatment. The result has been the transformation of the tetragonal phase to an orthorhombic phase. The effect of this treatment on solid particle erosion properties is investigated here for a set of commercial partially stabilized magnesiadoped zirconia (Mg-PSZ) samples.     

Ageing of a phosphate ceramic used to immobilize chloride contaminated actinide waste

A process for the immobilization of intermediate level waste containing a significant quantity of chloride using Ca₃(PO₄)₂ as the host material has been developed. Waste ions are incorporated into two phosphate-based phases, chlorapatite [Ca₅(PO₄)₃Cl] and spodiosite [Ca₂(PO₄)Cl]. Non-active trials performed using Sm as the actinide surrogate demonstrated the durability of these phases in aqueous solution. Trials of the process, in which actinide-doped materials were used, were performed at PNNL which confirmed the wasteform resistant to aqueous leaching. Initial leach trials conducted on ²³⁹Pu/²⁴¹Am loaded ceramic at 313 K/28 days gave normalized mass losses of 1.2 × 10⁻⁵ g m⁻² and 2.7 × 10⁻³ g m⁻² for Pu and Cl, respectively. In order to assess the response of the phases to radiation-induced damage, accelerated ageing trials were performed on samples in which the ²³⁹Pu was replaced with ²³⁸Pu. No changes to the crystalline structure of the waste were detected in the XRD spectra after the samples had experienced an α radiation fluence of 4 × 10¹⁸ g⁻¹. Leach trials showed that there was an increase in the P and Ca release rates but no change in the Pu release rate.     

Exploring the unknowns involved in the transformation of muscle to meat

Meat quality development, or the transformation of muscle to meat, involves a myriad of biochemical pathways that are largely well-studied in living muscle tissue. However, these pathways are less predictable when homeostatic ranges are violated. In addition, there is far less known about how various management or environmental stimuli impact these pathways, either by substrate load or altered cellular environment. Likewise, it is largely accepted that oxygen plays little to no role in the conversion of muscle to meat, as anaerobic metabolism predominates in the muscle tissue. Even so, the oxygen tension within the tissues does not fall precipitously at exsanguination. Therefore, transition to an anaerobic environment may impact energy metabolism postmortem. Antemortem handling, on the other hand, clearly impacts meat quality development, yet the exact mechanisms remain a mystery. In this paper, we will attempt to review those factors known to affect postmortem energy metabolism in muscle and explore those areas where additional work may be fruitful.     

Reactivation of hippocampal ensemble activity patterns in the aging rat.

In young rats, the pattern of neuronal ensemble activity correlations expressed among hippocampal pyramidal cells during behavior persists during subsequent quiet wakefulness and slow-wave sleep, a process that may facilitate the consolidation of episodic memories. The present study explored the hypothesis that age-related changes in this process might contribute to memory impairments observed during normal aging. Neuronal activity was recorded from CA1 pyramidal cells, and in both young and old rats, there was a strong similarity between the resting epoch activity patterns and those from the preceding behavior epoch. This similarity was strongest during sharp-wave events. There were no detectable differences in the reactivation process or the decay rate between the young and old age groups. Thus, age differences in spatial memory do not appear to be explainable by differences in the spontaneous reactivation of familiar patterns within the hippocampus during the immediate postbehavior period. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The molecular karyotype of the megabase chromosomes of Trypanosoma brucei and the assignment of chromosome markers

We present the molecular karyotype of the megabase chromosomes of Trypanosoma brucei stock TREU927/4 (927). We have identified 11 diploid chromosomes ranging in size from 1 to 5.2 Mb approximately and pairs of homologues differ in size by up to 15%. A total of 401 cDNA probes were hybridised to T. brucei stock 927 chromosomes and 168 chromosome-specific markers were defined. Most of these markers were hybridised to the separated chromosomal DNA of two other cloned field isolates and four F1 progeny clones from a laboratory cross. The chromosomes vary in size by up to two and a half times between stocks and the DNA content of the 11 pairs of homologues varies by up to 33% in different stocks. Stock 927 contains the smallest chromosomes and the least nuclear genomic DNA. Nevertheless, all 11 syntenic groups of cDNA probes are maintained in all stocks. In the F1 hybrids only we have identified one extra PFG band to which none of our probes hybridise. We have shown that probes thought to be specific for the bloodstream-form variant surface glycoprotein expression sites hybridise to different chromosomes in different stocks and may hybridise to either one or both of a homologous pair of chromosomes. We have also determined the chromosomal location of the ribosomal RNA gene arrays.     

An alternative synthesis and mobile phase ion chromatography of alkanedisulfates

Preparation of alkane disulfates using chlorosulfonic acid results in a crude product containing significant amounts of chloride, sulfate, and hydroxyalkanesulfates. This paper describes an alternative synthesis using trimethylamine:sulfur dioxide complex in anhydrous pyridine. Workup with sodium hydroxide and washing in acetone results in a crude product with less than 1% inorganic impurity and ∼0–3% hydroxyalkanesulfate. Recrystallization from acetone reduces the inorganic impurity to less than 0.1%. Alkanedisulfates can be separated from the corresponding hydroxyalkanesulfates, chloride, and sulfate using mobile phase ion chromatography with tetrabutylammonium hydroxide (TBAOH) as the ion-pairing agent and acetonitrile as the organic modifier. With the crude octanedisulfate and decanedisulfate product mixes, the alkanedisulfate is retained more strongly by the ion-pairing effect; but with the tetradecane species, hydrophobic interaction dominates and the tetradecanedisulfate elutes before the hydroxytetradecanesulfate. The choice of acetonitrile gradient and TBAOH is particularly important for the separation of the dodecane derivatives because the opposing effects of polarity (hydrophobic effect) and electrostatic interaction with TBAOH are of similar strength.     

Functional Organic Semiconductors Assembled via Natural Aggregating Peptides

Specific peptide sequences designed by inspection of protein–protein interfaces have been identified and used as tectons in hybrid functional materials. Here, an 8‐mer peptide derived from an interface of the peroxiredoxin family of self‐assembling proteins is exploited to encode the assembly of the perylene imide‐based organic semiconductor building blocks. By augmenting the peptide with additional functionality to trigger aggregation and manipulate the directionality of peptide‐semiconductor coupling, a series of hybrid materials based on the natural peptide interface is presented. Using spectroscopic probes, the mode of self‐assembly and the electronic coupling between neighboring perylene units is shown to be strongly affected by the number of peptides attached, and by their backbone directionality. The disubstituted material with peptides extending in the N to C direction away from the perylene core exhibits strong coupling and long‐range order, both attractive properties for electronic device applications. A bio‐organic field‐effect transistor is fabricated using this material, highlighting the possibilities of exploiting natural peptide tectons to encode self‐assembly in other functional materials and devices.