Autoxidation of saturated fatty acids. II. The determination of the site of hydroperoxide groups in autoxidizing methyl palmitate

The monohydroperoxides of methyl palmitate oxidized at 150C were concentrated, purified, and reduced to yield a mixture of isomers of monohydroxy palmitate. No evidence of unsaturation in these molecules could be obtained, and no direct method for the resolution or identification of the individual isomers was found. Nuclear magnetic resonance (NMR) spectroscopy of the reduced esters suggested that the hydroxy groups were not located at either end of the chain of the fatty ester. To establish the location of the initial oxidative attack on saturated esters, the reduced esters of oxidized methyl palmitate were chemically cleaved at the location of the hydroxy group by means of chromium trioxide oxidation and by the Beckmann transformation. The resulting mono- and dibasic fatty acids were methylated and analyzed by gas chromatography. This analysis indicated that the oxidation of methyl palmitate did not occur selectively at one location along the ester. Although all carbon atoms can apparently be oxidized, preferential oxidation was observed toward the center of the molecule.     

Observations on the pia-arachnoid of the anterior median fissure and the posterior median sulcus of the fetal spinal cord of the albino mouse

A pericentric inversion of an X chromosome [46,X,inv(X)(p11q28] with no detectable deletions was ascertained by amniocentesis for prenatal diagnosis in a 42-year-old woman. No defintive counsel could be offered as such an inversion had not been previously reported. At 1 year, the infant appears normal. These data and the review of other recently published karyotypes suggest an absence of a somatic position effect in the human X chromosome and possible biases of ascertainment or possible alternative karyotypic interpretations of some previously reported inv(X) cases.     

The identification of radiolytic decomposition products from tributyrin

In order to facilitate the detection of radiolytic products of triglycerides which may be of higher molecular weight than their precursor, a low molecular weight triglyceride, tributyrin, was selected as a model system, and gel permeation chromatography was used to effect their separation. The irradiation treatment was conducted under vacuum at 50 Mrad. Radiolytic products were collected by a precolumn technique for the highly volatile compounds; a combination of cold finger distillation and gel permeation for the less volatile fractions and finally gel permeation chromatography of the residue after distillation for the higher molecular weight compounds. A large number of compounds expected on the basis of previous work were identified in the present work from irradiated tributyrin. In addition, the techniques employed permitted the identification of several new compounds. These include butanetriol triesters, erythritol tetraesters, and other polyglycol polyesters.     

Dynamic Microcapsules with Rapid and Reversible Permeability Switching

Dynamic microcapsules are reported that exhibit shell membranes with fast and reversible changes in permeability in response to external stimuli. A hydrophobic anhydride monomer is employed in the thiol–ene polymerization as a disguised precursor for the acid‐containing shells; this enables the direct encapsulation of aqueous cargo in the liquid core using microfluidic fabrication of water‐in‐oil‐in‐water double emulsion drops. The poly(anhydride) shells hydrolyze in their aqueous environment without further chemical treatment, yielding cross‐linked poly(acid) microcapsules that exhibit trigger‐responsive and reversible property changes. The microcapsule shell can actively be switched numerous times between impermeable and permeable due to the exceptional mechanical properties of the thiol–ene network that prevent rupture or failure of the membrane, allowing it to withstand the mechanical stresses imposed on the capsule during the dynamic property changes. The permeability and molecular weight cutoff of the microcapsules can dynamically be controlled with triggers such as pH and ionic environment. The reversibly triggered changes in permeability of the shell exhibit a response time of seconds, enabling actively adjustable release profiles, as well as on‐demand capture, trapping, and release of cargo molecules with molecular selectivity and fast on‐off rates.     

Trauma, depression, and comorbid PTSD/depression in a community sample of Latina immigrants.

Trauma exposure is frequently overlooked as a risk factor for psychiatric morbidity among studies with Latinos. The purpose of this study was to examine the relationships among trauma history, immigration-related factors, and mental health status among Latina immigrants. The current study used baseline data from a randomized clinical trial for the treatment of depression of 64 women with comorbid posttraumatic stress disorder and depression, 69 with depression-only, and 61 with no Axis I mental disorder. Sixty-four percent of the sample was Central American and 75% reported trauma exposure. Multinomial logit analysis suggested fewer years in the United States was associated with worse mental health status. Having a nonmarried marital status was also associated with worse mental health. Reporting four or more types of traumatic events was associated with an increase in the probability of comorbidity. These findings have important implications for future research and clinical practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Radiolysis of lipids in monolayers. I. Saturated fatty acids

In order to study the effect of molecular orientation on the behavior of lipids when exposed to high energy radiation, model systems of palmitic acid or ethyl palmitate adsorbed as monolayers on silica were irradiated with⁶⁰Co at 25 Mrad under vacuum, and the volatile products compared with those of control samples irradiated in bulk. Major quantitative differences were observed. More of the C _n−1 alkane relative to the shorter-chain members of the homologous series were formed in bulk samples as compared to samples in monolayer. The C _n−2 alkene and C _n aldehyde also were formed in greater quantities in bulk. These observations are explained on the basis of a reduced preferential cleavage near the carbonyl group and a restricted mobility of free radical intermediates, in the case of the monolayers.     

Thermal oxidation of lipids in monolayers. I. The nature of binding on silica

The purpose of this study was to investigate whether the oxidation of lipids in the ordered state differs from that in the bulk phase. Simple model systems of lipids adsorbed on silica were used as a monolayer model system. This part of the study was designed to provide a better understanding of the nature of lipid adsorption on silica. Isotherms were determined for a number of substrates differing in chain length and functional groups. The number of molecules adsorbed per unit area of silica was found to decrease with increasing chain length. Binding was also dependent on the type of functional group present. For the same length, the amount adsorbed was in the following order: alcohol >acid> ester, whereas binding strength was as follows: acid >ester> alcohol.     

GC/MS analysis of some long chain esters,ketones and propanediol diesters

Identification of radiolysis products which are formed in lipids in the range of molecular weights from 400-600 has been established on the basis of gas chromatography/mass spectrometry (GC/MS) studies of long chain authentic samples of alkyl esters, ketones and propanediol diesters. This paper describes the GC/MS behavior of these compounds. Double hydrogen rearrangement was found to be the predominant ion in the spectrum of long chain saturated esters whereas in the unsaturated esters, a peak corresponding to the loss of alcohol from the molecular ion was more pronounced. On the contrary to short chain ketones, McLafferty rearrangement did not appear to be the major fragmentation in the spectrum of saturated and unsaturated long chain ketones. α-Cleavage was found to be the predominant fragmentation in the spectrum of these ketones. The “McLafferty + 1” rearrangement peak was more pronounced for the long chain ketones than those found in the spectrum of smaller ketones. Fragmentation patterns of propanediol diesters were shown to be similar to those in triglycerides, giving rise to predominant peaks corresponding to acylium ion [RCO]⁺ and parent minus acyloxy ion [R-COO]⁺.     

2-Alkylcyclobutanones from the radiolysis of triglycerides

A cyclic compound was isolated from the radiolytic products of each of the simple triglycerides containing C₆, C₈, C₁₀, C₁₂, C₁₄, C₁₆ and C₁₈ fatty acids. In each case the compound was identified as the 2-alkylcyclobutanone of the same carbon number as the precursor fatty acid. A mechanism is proposed for the production of these compounds which involves the formation of a six-membered ring intermediate, cyclization and cleavage at the acyl-oxy bond.