Quantitative effects of dietary polyunsaturated fats on the composition of fatty acids in rat tissues

A method combining data on fatty acid composition into subsets is used to illustrate general relative competitive selectivities in the metabolic and transport events that maintain fatty acid compositions in tissue lipids and to minimize differences among tissues or species in the amount of individual fatty acids. Fatty acid compositions of triglycerides and phospholipids in several tissues of the rat were maintained with simple relationships between the exogenous n−3 and n−6 dietary polyunsaturated fatty acids and the endogenous n−7 and n−9 types of fatty acid. The general pattern of fatty acids in triglycerides was similar for liver, plasma and adipose tissue, averaging about 30% as saturated acids, 67% as 16- and 18-carbon unsaturated acids and only about 2% as 20- and 22-carbon highly unsaturated acids. The tissues maintained a linear relationship between the amount of 18-carbon polyunsaturated fatty acids in the diet and in the tissue triglycerides, with the proportionality constant for 18∶3n−3 being 60% of that for 18∶2n−6. The total phospholipids of liver, plasma and red blood cells maintained about 45% of the fatty acids in the form of saturated fatty acids and 20–30% as 20- and 22-carbon highly unsaturated fatty acids irrespective of very different proportions of n−3, n−6 and n−9 types of fatty acids. In all three tissues, the 20-carbon highly unsaturated fatty acids of the n−3, n−6 and n−9 type were maintained in a competitive hyperbolic relationship with apparent EC₅₀ values for dietary 18∶2n−6 and 18∶3n−3 near 0.1% of dietary calories. The consistent quantitative relationships described in this study illustrate an underlying principle of competition among fatty acids for a limited number of esterification sites. This approach may be useful in predicting the influence of diet upon tissue levels of the substrates and antagonists of eicosanoid biosynthesis.     

Phase formations during mechanochemical synthesis of PbTiO<Subscript>3</Subscript>

Lead titanate nanopowders were fabricated by mechanochemical synthesis from lead oxide and titanium dioxide. The milling process has been carefully investigated by X-ray diffraction and X-ray excited photoelectron spectroscopy. The first traces of perovskite phase were detected after 5 h synthesis. It was found that intermediated phases (Ti₁₀O₁₈ and Pb₃O₄) have been formed at the early stage of synthesis. The 50 h milling results in single perovskite phase with average crystallite size of 20 nm.     

Copper complexing properties of melanoidins and marine humic material

Melanoidins, condensation products of sugars and amino acids, represent a key link in the transformation of polysaccharides to humic material in the marine environment. We investigated the complexing capacity of melanoidins that were prepared in deionized water and seawater and separated into different molecular mass fractions. The copper complexing properties of humic material isolated from marine lagoon sediments were determined for comparison. Melanoidins prepared using condensation times longer than two days exibit complexation properties towards copper ions that appear to depend on the basicity of the amino acid precursor and the molecular mass of the product. Pseudomelanoidins, prepared from glucose only, do not complex copper ions at all, regardless of the molecular mass. The highest copper complexing capacity value among melanoidins was measured for a glucose-lysine melanoidin with molecular mass fraction >10 kD (L(T)=2.1x10(-7) molCu(2+)/L). Melanoidin prepared from glucose and glutamic acid >10 kD was similar in complexing capacity to fulvic acid (1-20 kD molecular mass) isolated from lagoon sediments. The presence of calcium and magnesium ions and other macro and microconstituents in the seawater used to prepare melanoidins influences its complexing properties towards metal ions.     

Pattern of volatile compounds in dominant and subordinate male mouse urine

The urinary volatiles from dominant and subordinate male mice were chromatographically compared, both immediately and seven days after dominant-subordinate relationships between pairs were formed. Statistical comparison of the peak areas of volatile constituents present in male urine revealed that 16 urinary compounds exhibited substantial concentration differences depending upon social status of the animals. Urinary dihydrofurans, ketones, and acetates exhibited a significant, long-term (seven-day) decrease in the urine of subordinates when compared to control and dominant males. Two sesquiterpenic compounds, - and -farnesene, were elevated only in the dominant urine one week after dominance was established. 2-(sec-Butyl)-4,5-dihydrothiazole was found in higher concentration in bladder or excreted urine of dominant males when compared to subordinates. Of the 16 compounds subjected to statistical analysis, four exhibited hormonal dependency: - and -farnesene, dehydro-exo-brevicomin, and 2-(sec-butyl)-4,5-dihydrothiazole. Neither dehydro-exo-brevicomin nor 2-(sec-butyl)-4,5-dihydrothiazole was present in the urine of immature and castrated males. Testosterone treatment restores their presence in male urine. Also, - and -farnesene were absent in the urine of immature males and significantly reduced in the urine of castrated males. The absence of - and -farnesene in bladder urine suggests that one of the sex-accessory glands may be the site of their origin.     

Hyper-crosslinked sorbents for hemoperfusion

Pore structure changes of swelling sorbents, which were obtained from styrene and divinylbenzene (DVB) by additional crosslinking with α,α′-dichloro-p-xylene in the presence of tin chloride catalyst and in dichloroethane solution, were examined. It was found that the amount of dichloroxylene influences the swelling decrease and the increase of sorption ability of sorbents for chemical compounds with low molecular weight. Hemocompatibility was imparted to the sorbent and it was useful for hemoperfusion when a small amount of sulfonyl groups (about 0.2 mmol/g) had been introduced.     

Transdermal and buccal delivery of methylxanthines through human tissue in vitro

We examined the in vitro permeation of central nervous stimulants—caffeine, theophylline, and theobromine across human skin with the aid of six chemical enhancers. It was found that oleic acid was the most potent enhancer for all three methylxanthines. Further optimization studies with different solvents showed that caffeine transport could be enhanced to give flux values up to 585 μg/cm².hr^-1. Theobromine and theophylline delivery rates proved insufficient. An additional study involving a buccal tissue equivalent showed that this membrane was more permeable than skin for all model actives tested and would offer an alternate way of delivery.     

Changes in the Cell Wall Proteome of Leaves in Response to High Temperature Stress in Brachypodium distachyon

High temperature stress leads to complex changes to plant functionality, which affects, i.a., the cell wall structure and the cell wall protein composition. In this study, the qualitative and quantitative changes in the cell wall proteome of Brachypodium distachyon leaves in response to high (40 °C) temperature stress were characterised. Using a proteomic analysis, 1533 non-redundant proteins were identified from which 338 cell wall proteins were distinguished. At a high temperature, we identified 46 differentially abundant proteins, and of these, 4 were over-accumulated and 42 were under-accumulated. The most significant changes were observed in the proteins acting on the cell wall polysaccharides, specifically, 2 over- and 12 under-accumulated proteins. Based on the qualitative analysis, one cell wall protein was identified that was uniquely present at 40 °C but was absent in the control and 24 proteins that were present in the control but were absent at 40 °C. Overall, the changes in the cell wall proteome at 40 °C suggest a lower protease activity, lignification and an expansion of the cell wall. These results offer a new insight into the changes in the cell wall proteome in response to high temperature.     

Infrared kinetic/structural studies of barrier reformation in intact stratum corneum following thermal perturbation

Stratum corneum, the outermost layer of the epidermis, constitutes the main barrier to permeability in skin. As such, it has been the target of many approaches for transdermal drug delivery based on methods involving transient modifications of the barrier. An infrared (IR) spectroscopic method has been developed to monitor the kinetics of barrier restoration following an external perturbation. In the current case, temperature perturbation was selected as a convenient means to induce structural changes in the barrier. The method is based on the observation that the ordered lipid phases of the barrier in isolated human stratum corneum exist in part in orthorhombically packed subcells. Such phases display a characteristic splitting of the CH2 rocking vibrations with component frequencies at 720 and 729 cm(-1). The latter is reliably diagnostic for orthorhombic phases and is markedly reduced in intensity following a thermal perturbation to 55 degrees C. The kinetics of barrier recovery following quenching to either 25 degrees C or 30 degrees C were monitored by tracking the restoration of the 729 cm(-1) band intensity. The kinetics were dominated by exponential growth in the initial stages, followed by linear increases at longer times. The half lives for exponential growth regimes were 52.4 h for the 25 degrees C quench and 13.8 h for the 30 degrees C quench. These values are in reasonable accord with those determined with more phenomenological approaches, typically based on restoration of some barrier function. This novel method for monitoring structural reorganization kinetics in intact stratum corneum can readily be extended to evaluate barrier recovery following a variety of treatments used to enhance drug delivery.