Metabolism of 1,2-(1-14C) dipalmitoyl phosphatidylcholine in the developing brain

Thirteen-day-old rats were divided into two groups; one group received 1,2-(1-¹⁴C) dipalmitoyl phosphatidylcholine and the other 1-¹⁴C palmitic acid in the form of an intraperitoneal injection. One half of the total number of rats in each group was sacrificed 24 hr after injection, and the other half was allowed to survive for 17 days after the injection. Radioactivity incorporated into brain and liver total lipids and into individiual polar lipid components of the brain was determined at both intervals. Phosphatidylcholine was isolated and partially deacylated with phospholipase A₂ fromCrotalus Admanteus venom. The ratio of radioactivity FA 2/FA 1 (fatty acid attached to 2 and 1 carbon of the glycerol moiety) 24 hr after the injection was 8.3, when the tracer was radioactive phosphatidylcholine, compared to only 0.7 when radioactive palmitate was injected. From this different labeling ratio and different pattern of labeling the polar lipid components, it was concluded that the radioactive phosphatidylcholine was not deacylated completely before being taken up directly into the brain. Possibilities are discussed to show that the observed radioactive ratio could result from direct uptake of intact phosphatidylcholine, with little or no restriction from the blood brain barrier system, followed by partial degradation by phospholipase A₁ in the brain itself. Presented in part at the AOCS Meeting, New Orleans, April 1973.     

RAFT polymerization of hydrophobic acrylamide derivatives

Several hydrophobic acrylamide derivatives: the N-tert-butylacrylamide (TBAm), the N-octadecylacrylamide (ODAm) and the N-diphenylmethylacrylamide (DPMAm) have been polymerized by reversible addition-fragmentation chain transfer (RAFT) process in the presence of azobis(isobutyronitrile) (AIBN) and tert-butyl dithiobenzoate (tBDB) as initiator and reversible chain transfer agent (CTA), respectively. Homopolymerizations were compared as regards to kinetics and molecular weight (MW) control, and the results were discussed according to the monomer structure and to the influence of several experimental parameters, such as the [CTA]/[AIBN] ratio and the [Monomer]/[CTA] ratio. TBAm and ODAm monomers exhibited a well controlled polymerization (polydispersity index (PDI) below 1.3 for number average molecular weight (M_n) until 30,000 g mol⁻¹) over a wide range of conversion (until 70%), whereas DPMAm conversion remained below 20% partly due to steric hindrance. The molecular weights of several poly(TBAm) samples determined by four independent analytical techniques, size exclusion chromatography/on-line light scattering detector (SEC/LSD), ¹H NMR, ¹³C NMR and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), were in agreement, close to the theoretical ones. Moreover, the MALDI-TOF MS analyses suggested the presence of parasite chains resulting from irreversible termination onto RAFT intermediate radicals.     

Strain-rate sensitivity index of thermoplastics

Strain-rate sensitivity index, m, values of several thermoplastics (HDPE, PP, PMMA, PS, PVC, PC, and PA) were determined at ambient temperature by both variable strain-rate and stressrelaxation methods. Specimens were loaded in tension in the elastic portion of the stress-strain curve at various strain rates and the load was recorded as a function of elongation. Index values were determined from the relation $m = [\partial \ln (\sigma )]/[\partial \ln (\dot e)]_{e, T} $ . Specimens were also loaded in tension at constant strain rate to the proportional limit, loading was halted, and the load was recorded as a function of time at constant strain. A numerical algorithm was implemented to minimize the root-mean-square difference between an empirical equation and the experimental data, i.e. $$\Phi (n, \tau ) = \left( {1/N\sum\limits_i {\{ P_o \exp [ - (t_i /\tau )^n ] - P(t_i )\} } ^2 } \right)^{1/2} $$ The characteristic time parameter, (τ), and the rate-of-decay parameter, n, were found when Φ(n,τ) was minimized. Index values were determined from the relation $m = {\text{[}}\partial {\text{ln}} {\text{(}}P{\text{)]/[}}\partial {\text{ln(}} {\text{ - }} \dot P{\text{)]}}_{e,{\text{ }}T} $ . A marked difference in index values derived from both experimental methods indicates that different processes are operative in each case. Index values are qualitatively evaluated in terms of cohesive energy density, side-chain group molar volume, and main-chain group flexibility.     

The disagreement power of an adversary

At the heart of distributed computing lies the fundamental result that the level of agreement that can be obtained in an asynchronous shared memory model where t processes can crash is exactly t?+?1. In other words, an adversary that can crash any subset of size at most t can prevent the processes from agreeing on t values. But what about all the other ${2^{2^n - 1} - (n+1)}$ adversaries that are not uniform in this sense and might crash certain combination of processes and not others? This paper presents a precise way to classify all adversaries. We introduce the notion of disagreement power: the biggest integer k for which the adversary can prevent processes from agreeing on k values. We show how to compute the disagreement power of an adversary and derive n equivalence classes of adversaries.     

Verifying common-cause reduction rules for fault tolerant systems via simulation using a stress-strength failure model

Redundant programmable electronic systems are commonly used in many industrial processes for safety protection and high availability process control. Common-cause failures can significantly reduce the benefits of the redundancy designed into this equipment. To improve on this situation, a number of qualitative design rules for reducing common cause failures have been put forth. However, these rules have not previously been subjected to quantitative verification. It is important to understand the magnitude of common cause failures and how this varies with design changes. This information can be used to show how system designs can be improved by lowering common cause failure rates. A stress-strength simulation was created to simulate the failures of a programmable electronic system under different design scenarios and the common cause failure rate was computed for each case. The simulation results not only confirm that the qualitative design rules lowered common cause failure rates but also provide some quantitative assessment of how large the improvements can be in various cases.     

Direct and indirect antioxidant properties of α‐lipoic acid and therapeutic potential

Diabetes has emerged as a major threat to worldwide health. The exact mechanisms underlying the disease are unknown; however, there is growing evidence that the excess generation of reactive oxygen species (ROS) associated with hyperglycemia, causes oxidative stress in a variety of tissues. In this context, various natural compounds with pleiotropic actions like α‐lipoic acid (LA) are of interest, especially in metabolic diseases such as diabetes. LA, either as a dietary supplement or a therapeutic agent, modulates redox potential because of its ability to match the redox status between different subcellular compartments as well as extracellularly. Both the oxidized (disulfide) and reduced (di‐thiol: dihydro‐lipoic acid, DHLA) forms of LA show antioxidant properties. LA exerts antioxidant effects in biological systems through ROS quenching but also via an action on transition metal chelation. Dietary supplementation with LA has been successfully employed in a variety of in vivo models of disease associated with an imbalance of redox status: diabetes and cardiovascular diseases. The complex and intimate association between increased oxidative stress and increased inflammation in related disorders such as diabetes, makes it difficult to establish the temporal sequence of the relationship.     

Hospital Diet Enriched With Rapeseed or Sunflower Oils Is Associated With a Decrease in Plasma 16:1n‐7 and Some Metabolic Disorders in the Elderly

We recently demonstrated that the prevalence of dysglycemia was high among hospitalized elderly people who were fed a low fat diet (27.7% of energy) and was positively associated with plasma 16:1n‐7, an indicator of de novo lipogenesis (DNL). Fatty acids in the DNL pathway have been shown to be associated with a higher risk of metabolic syndrome (MetS). The purpose of this study was to investigate the potential beneficial effects of fat enrichment (up to 34.1%en) of the hospital diet in 111 patients (30 men and 81 women, 84 ± 7 years) during 6 weeks. Based on gender, they were randomly given a diet supplemented either with rapeseed oil (RO) or with sunflower oil (SO). Fatty acids of cholesteryl esters and erythrocyte phospholipids and markers of metabolic disorders were evaluated before and after dietary intervention. Both enriched diets significantly, and to a similar extent, decreased (1) the overall prevalence of dysglycemia (by 25–33%) and MetS (by 31–43%) and (2) plasma 16:1n‐7 mol% in men and women. Dysglycemia prevalence adjusted by the diets was reduced in men versus baseline; no change was found in women. Enrichment of the diet with RO or SO resulted in a difference in fatty acid compositions, that is, EPA (mol%) and the omega‐3 index increased with RO, while proportions of 18:1n‐7, 18:1n‐9, and EPA decreased with SO. These findings highlight the need for adequate fat intake in the elderly. For supplementation of the hospital diet, RO, which led to a higher proportion of circulating n‐3 polyunsaturated fatty acids (PUFA) and is known to be beneficial, may be preferred to SO.     

Is it possible to predict gas yields of any biomass after rapid pyrolysis at high temperature from its composition in cellulose, hemicellulose and lignin?

Ligno-cellulosic biomass from different sources presents very variable compositions. Consequently, there is a wide variation in the nature and quantities of gaseous products obtained after thermal treatment of biomasses.The objective of this work is to establish a link between the composition of a biomass and its pyrolysis gas yields and composition. Experimental flash pyrolysis of several biomasses at a temperature of 950 °C and a gas residence time of about 2 s was carried out. An attempt was then made to predict gas yields of any biomass according to its composition. We show that an additivity law does not allow the gas yields of a biomass to be correlated with its fractions of cellulose, hemicellulose and lignin. Several potential explanations are then offered and quantitatively demonstrated: it is shown that interactions occur between compounds and that mineral matter influences the pyrolysis process.     

Chemical characterization and origin of dyes used in the manufacture of Beninese cultural heritage objects

Six objects of Beninese cultural heritage provided by African and Confluences museums of Lyon (France) were the focus of this study. The characterization of colored compounds was achieved using: microchemical tests, Fourier transform infrared spectroscopy and liquid chromatography coupled to a photodiode array detector. The main results reflect the presence of organic compounds like indigotin, 2‐hydroxynaphthoquinone, and mineral ions such as Al³⁺, S^2?, Na⁺, and Fe³⁺. Dyes were identified from Philenoptera cyanescens (Yoruba indigo) and Lawsonia inermis L. (henna); pigments were identified as laundry blue, Prussian blue, and iron oxides. All of these data therefore make possible the conservation and the restoration of these objects while maintaining their visual and functional integrity.     

Children's memory for medical emergencies: 2 years later.

Long term recall of medical emergencies (including both injury and hospital treatment) by 2- to 13-year olds was assessed 2 yrs after injury. Event identity was important: Children recalled injury details better than hospital treatment. Ninety-six children were interviewed 3 times prior to the 2-year recall; amount recalled decreased only for hospital treatment details, although accuracy of recall decreased for both injury and treatment. Twenty-one children were interviewed only twice prior to the 2-year interview. An extra interview 1 year after their injury had little effect on how much older children recalled about injury details, but it helped younger children recall the less memorable hospital event. The extra interview also helped all children maintain accuracy when recalling hospital details, but was unnecessary for the more memorable injury event. Implications for children's testimony are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)