Influence of sex and gonadal hormones on lipid metabolism in essential fatty acid-deficient rats

Previous work has shown differences between male and female rats in their ability a) to mobilize linoleic acid from adipose tissue when the supply is limited; b) to maintain higher levels of circulating and liver arachidonic acid when dietary linoleic acid is limited; c) to prevent accumulation of cholesteryl ester (CE) in the liver; and d) to increase the proportions of polyunsaturated fatty acids (PUFA) in their plasma lecithins. Recent studies are reviewed which show that a) essential fatty acid (EFA)-deficient rats exhibit the same kinds of sex differences as do rats on complete diets; b) these differences are mediated or at least influenced by estrogen; c) some of the differences may be attributed to differences in body size which result in less need for PUFA in structural phospholipid (PL); d) the rate of conversion of linoleic to arachidonic acid may differ under certain experimental conditions; and e) female rats have higher proportions of stearic and arachidonic acids in their liver lecithins than do males, which may relate to their higher rate of lecithin synthesis via methylation of phosphatidyl-ethanolamine. Presented at the symposium on essential fatty acids in honor of George O. Burr, AOCS Meeting, Loss Angeles, April 1968.     

Tensile properties and morphology of S2Cl2 treated PVC-g-butly rubber

Summary We have grafted butyl rubber from PVC under a variety of conditions. The physical-mechanical properties of these graft copolymers have been examined both before and after extraction with hexane of the ungrafted butyl rubber. We have found a significant increase in the tensile strength of these materials upon S₂Cl₂ treatment (curing) in THF solution. This increase was observed even with unextracted copolymers. Electron micrograph studies suggest that curing causes an aggregation of the butyl rubber segments into crosslinked domains.     

Lung lamellar bodies lack certain key enzymes of phospholipid metabolism

Palmitoyl CoA-glycerol-3-phosphate acyltransferase, phosphatidate phosphohydrolase, and phospholipase A were assayed in subcellular fractions of rat lung, including lamellar bodies, the putative site of storage and secretion of lung surfactant. The specific activity of each of these enzymes in lamellar bodies was relatively low and could be entirely accounted for by a small contamination of the lamellar bodies fraction by microsomes, as quantitated by the presence of the microsomal marker reduced triphosphopyridine nucleotide cytochromec reductase. These data indicate that lamellar bodies are not the site of synthesis of the lipid component of pulmonary surfactant by pathways involving these enzymes.     

Production of Oxidized Derivatives of 5-Hydroxymethylfurfural (HMF)

5-Hydroxymethylfurfural (HMF) was catalytically converted in a bench-scale flow reactor to the oxidized derivatives 2,5-furandicarboxylic acid (FDCA), 5-formyl-2-furancarboxylic acid (FFCA), and 2,5-diformylfuran (DFF). Conversions and selectivities to these products depended on oxidant, pH, catalyst, and reactor operating conditions. The feasibility of producing these species in a flow reactor was demonstrated.     

Structure and dynamic mechanical properties of highly oriented PS/clay nanolaminates over the entire composition range

A series of highly oriented model polymer/clay nanocomposites (nanolaminates) are prepared via a newly developed solvent deposition process with compositions ranging from neat polymer to neat organoclay. Morphology is analyzed via scanning electron microscopy (SEM) and wide-angle X-ray diffraction (WAXD) while thermogravimetric analysis (TGA) is used to confirm composition and solvent removal. Dynamic mechanical analysis (DMA) is used to examine the trends in stiffness and damping properties as the composition is shifted from polymer-rich to polymer-starved. The role of the organoclay modifier in determining the structure and properties of these nanolaminates is also reported. Experimental moduli are compared to relevant micromechanical models including Tandon-Weng and Halpin-Tsai. These comparisons allow for the identification of deviations from the behavior expected of conventional blends and composites, highlighting the effects of nanostructuration and the presence of the organic modifier on materials behavior.     

Nondestructive examination of epoxy adhesive-bonded structures exposed to a humid environment: A comparison of low- and high-frequency dielectric measurements

Broadband dielectric measurements (10 ?2 to 3 GHz) are reported on the effects of exposure of thick film adhesive-bonded structures to moisture. Measurement of the dielectric properties over a broad frequency range allows identification of water both in voids and as a molecular dispersion in the matrix. Changes in the low frequency region of the dielectric spectrum can be attributed to a combination of processes associated with plasticisation of the adhesive, interfacial polarisation effects, and hydration of the surface oxide layer. The data obtained are complemented by mechanical testing and failure analysis of the bond structure measured as a function of the time of exposure. This study indicates that for thick film adhesives the ageing characteristics are apparently independent of the surface treatment. In one of the joints studied an additional feature is identified which appears to correlate with the premature aging of the joint structure.     

Intracellular Distributions of the Anthracycline 4′-iodo-4′-deoxy-Doxorubicin and Essential Trace Metals Using Nuclear Microprobe Analysis

The nuclear microprobe is an instrument of multi-elemental analysis with micro-imaging capabilities. Particle Induced X-ray Emission (PIXE) and Rutherford Backscattering Spectrometry (RBS) were performed simultaneously on cultured cancer cells exposed to an antitumor agent, the anthracycline 4′-iodo-4′-deoxy-doxorubicin (IDX). Element mapping revealed that iodine and iron spatial distributions were strongly correlated, suggesting iron intracellular chelation by the anthracycline. Iron and iodine co-localizations were generally observed within the nucleus region. Quantitative determination of trace element concentrations shown that the average amount of endogenous trace metals did not change in cells after two hours exposure to 20 μM IDX. It suggests that no extra-cellular iron was imported into the cells during IDX uptake. From these results, it can be concluded that iron-IDX complexes might be formed in the intracellular space, at least when IDX is administered at 20 μM, and could participate to the various biological effects of anthracyclines antitumor drugs.