Phase separation of polymerized lipids in hybrid liposomes

Summary Hybrid liposomes were prepared from the mixture of dipalmitoyl phosphatidylcholine (DPPC) and di-2,4-octadecadiene phosphatidylcholine (DODPC), and their phase separation behaviours was analyzed. In hybrid liposome systems, two transition temperatures (18 and 41°C for DODPC and DPPC, respectively) were clearly observed by means of DSC and fluorescence techniques. These two transition temperatures were also found after polymerization of DODPC molecules in hybrid liposomes by the UV irradiation. These strongly suggest that DPPC and DODPC molecules do not dissolve well but form clusters in the membrane. This phase separation was directly confirmed by freeze-fracture TEM technique.     

The Analysis of Dimethylphenanthrenes by Direct Deposition Gas Chromatography – Fourier Transform Infrared Spectroscopy (GC-FTIR)

Abstract

Dimethylphenanthrenes (DMPs) occur as complex mixtures in crude oils and sedimentary rock extracts. Conventionally these mixtures are analysed using gas chromatography-mass spectrometry (GC-MS) employing a column with a medium polarity stationary phase. Under these conditions, complete resolution of the mixture is not achieved and several isomers co-elute. Furthermore, the mass spectra of these co-eluting isomers may be so similar that one is unable to differentiate between them, and their abundance may therefore not be determined.

In this paper, we describe the application of GC-FTIR as a complementary technique to GC-MS in the analysis of three co-eluting DMP isomers. Since each isomer has a unique infrared spectrum, the proportion of each in the mixture was determined by comparing the spectrum of the co-eluting compounds with the spectrum of each of the isomers. The result of this analysis was confirmed by the use of mordenite molecular sieves to separate the mixture into simpler fractions, and subsequent analysis by GC-MS and GC-FTIR.     

Molecular Species of Phospholipids with Very Long Chain Fatty Acids in Skin Fibroblasts of Zellweger Syndrome

The ratio of C_26:0/C_22:0 fatty acids in patient lipids is widely accepted as a critical clinical criterion of peroxisomal diseases, such as Zellweger syndrome and X-linked adrenoleukodystrophy (X-ALD). However, phospholipid molecular species with very long chain fatty acids (VLCFA) have not been precisely characterized. In the present study, the structures of such molecules in fibroblasts of Zellweger syndrome and X-ALD were examined using LC–ESI–MS/MS analysis. In fibroblasts from Zellweger patients, a large number of VLCFA-containing molecular species were detected in several phospholipid classes as well as neutral lipids, including triacylglycerol and cholesteryl esters. Among these lipids, phosphatidylcholine showed the most diversity in the structures of VLCFA-containing molecular species. Some VLCFA possessed longer carbon chains and/or larger number of double bonds than C_26:0-fatty acid (FA). Similar VLCFA were also found in other phospholipid classes, such as phosphatidylethanolamine and phosphatidylserine. In addition, VLCFA-containing phospholipid species showed some differences among fibroblasts from Zellweger patients. It appears that phospholipids with VLCFA, with or without double bonds, as well as C_26:0-FA might affect cellular functions, thus leading to the pathogenesis of peroxisomal diseases, such as Zellweger syndrome and X-ALD.     

2,3-Dihydrohomofarnesal: Female Sex Attractant Pheromone Component of Callosobruchus rhodesianus (Pic)

Callosobruchus rhodesianus (Pic) (Coleoptera: Chrysomelidae: Bruchinae) is a pest of stored legumes through the Afro-tropical region. In laboratory bioassays, males of C. rhodesianus were attracted to volatiles collected from virgin females. Collections were purified by various chromatographic techniques, and the biologically active component isolated using gas chromatographic-electroantennographic detection analysis. Gas chromatography-mass spectrometry and NMR analyses suggested that the active compound was 2,3-dihydrohomofarnesal, i.e., 7-ethyl-3,11-dimethyl-6,10-dodecadienal. The structure was confirmed by non-stereoselective and enantioselective total synthesis. Using chiral gas chromatography, the absolute configuration of the natural compound was confirmed as (3S,6E)-7-ethyl-3,11-dimethyl-6,10-dodecadienal. Y-tube olfactomter assays showed that only the (S)-enantiomer attracted males of C. rhodesianus. The (R)-enantiomer and racemate did not attract males, suggesting that the (R)-enantiomer inhibits the activity of the natural compound. In combination with previous reports about sex attractant pheromones of congeners, we suggest that a saltational shift of the pheromone structure arose within the genus Callosobruchus.     

Release Property of Progesterone from a Mixed-Base Suppository Consisting of Witepsol® W35 and Witepsol® E85

The mechanism of drug release from progesterone suppositories that consist of two types of hard fat (Witepsol® W35 and Witepsol® E85) was investigated. The strength, the thermodynamic characteristics, the surface structures, the drug release property, methylene blue penetration into suppositories, and change of surface structure after the dissolution test were employed for detecting characteristics of progesterone suppositories. The formulation with a mixing ratio of Witepsol W35 and Witepsol E85 at a 1:1 ratio showed the maximum strength value. The peak temperature of the suppositories showed a tendency to increase with increases in the ratio of Witepsol E85. The maximum height of the profiles measured with laser microscopy, from 20.8 μm to 29.2 μm, reached a maximum after 3 h of the dissolution test. When the suppositories were immersed in pH 7.4 phosphate buffer containing 0.5% methylene blue at 37°C, the penetrating area increased with time. The weight of the suppositories also increased with time. According to these findings, it was suggested that the release of drug from a mixed type of suppository containing progesterone was via the matrix and pores.     

Effect of reaction temperature on Fe–Al analcime formation

The effects of reaction period, temperature, and iron species on the zeolite framework type were studied in this work. Gismondine (GIS) is usually synthesized by hydrothermal method at 80°C from sodium metasilicate and aluminum nitrate as starting materials preferentially independent of the presence/absence of iron source. However, the present work revealed that pure analcime (ANA) could be formed at temperatures more than 120°C. A large polyhedral ANA crystal with a diameter of 180 μm was obtained even at a comparatively low temperature such as 150°C at a short reaction period of 1 week. The presence of iron source promoted the formation of pure ANA. Infrared spectroscopy, X-ray diffraction, and ICP-OES analysis suggested that the iron component added as a reactant was incorporated into the ANA framework through the isomorphous substitution for Al.     

Statistical failure analysis of adhesive resin cement bonded dental ceramics

The goal of this work is to quantitatively examine the effect of adhesive resin cement on the probability of crack initiation from the internal surface of ceramic dental restorations. The possible crack bridging mechanism and residual stress effect of the resin cement on the ceramic surface are examined. Based on the fracture-mechanics-based failure probability model, we predict the failure probability of glass-ceramic disks bonded to simulated dentin subjected to indentation loads. The theoretical predictions match experimental data suggesting that both resin bridging and shrinkage plays an important role and need to be considered for accurate prognostics to occur.     

Behavioral development and strain differences in perinatal mice (Mus musculus).

Examined the perinatal development of spontaneous body movements and reflexes in Slc:ICR, C3H/He, and BALB/c mice. Mice were observed from Day 18 (a day before normal parturition) to Day 21.5 of gestation. The developmental changes of spontaneous body movements and reflexes occurred quickly. Strain differences in behavioral development were detected in the duration of spontaneous body movements but not in the occurrence of reflexes. Hybrid mice were more active than their parental strains with regard to duration of spontaneous body movements. The rooting reflex and crossed extensor reflex in hybrid mice occurred more frequently on Day 18 than in their parental strains. These results indicate that the perinatal period is characterized by quick qualitative and quantitative changes in behavioral development and by the appearance of these genetic differences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)