The dietary regulation of acyltransferase and desaturase activities in microsomal membranes of rat liver

Dietary manipulation produces marked alterations in desaturase activities of rat liver microsomes with no concomitant changes in acyltransferase activities. Desaturation of stearoyl-CoA (Δ9-desaturase), linoleoyl-CoA (Δ6-desaturase), eicosatrienoyl-CoA (Δ5-desaturase) and eicosatrienoyl-phosphatidylcholine (Δ5-desaturase) was elevated in animals fed a corn oil diet and lowered in those fed a coconut oil diet compared to control animals. The Δ5-desaturase activities were also lowered in starved animals and elevated in starved animals refed a fat-free diet. However, no changes in acyl-CoA:1-acylsn-glycero-3-phosphocholine acyltransferase activity were observed in the membranes of animals maintained on any of the dietary regimens studied. These observations suggest that the desaturases of rat liver microsomes are regulated independently of the acyltransferases and that desaturation of eicosatrienoyl-phosphatidylcholine is regulated at the level of the desaturase itself and not by availability of the phospholipid substrate.     

Acyl-acyl carrier protein as substrate of the acyltransferase of rat liver microsomes

Acyl-acyl carrier protein (acyl-ACP) can serve as well as acyl-CoA as substrate of the 1-acyl-sn-glycero-3-phosphocholine (1-acyl-GPC) acyltransferase of rat-liver microsomes. The product of the acylation with either thioester substrate is predominantly phosphatidylcholine (PC) (92–95%). The acyl-group transferred from either myristoyl-CoA or myristoyl-ACP is located at the C-2 position of the phospholipid (PL). The apparent Km values for the myristoyl-CoA and myristoyl-ACP were 46 μM and 63 μM, and the corresponding apparent Vmax values were 1.0 and 1.6 nmol/min/mg. The rate of acylation with the acyl-ACP was unaffected by the addition of free CoA-SH. These data suggest that acyl-CoA and acyl-ACP are transferred to 1-acyl-GPC by the same or similar enzyme systems.     

The effects of selected organic solvents on the polymerization of acrylic acid to poly(ethylene terephthalate) by glow discharge

Six organic solvents with solubility parameters close to those of poly(ethylene terephthalate) (PET), namely, dimethyl sulfoxide, γ-butyrolactone, dimethyl formamide, pyridine, tetrachlorethane, and chlorobezene, were selected as swelling agents to promote the incorporation and the subsequent polymerization of acrylic acid to PET films. Variables studied included time of swelling, temperature of swelling, and length of glow discharge treatment. Elevated temperature had greater effects on the inclusion of the swelling agents and acrylic acid than did the length of swelling. Polymerization was generally increased with longer glow discharge treatment time. Surface wettability as well as the moisture regain values of PET films were greatly improved by both the solvent and the glow discharge treatments. The solvent-assisted glow discharge polymerization process was found to impose modification of PET films not restricted to the surface. Morphological modification of the treated PET was confirmed by DSC data.     

Effects of consciousness-raising groups on measures of feminism, self-esteem, and social desirability.

34 female undergraduates in 2 consciousness-raising groups were objectively assessed to determine whether changes relating to self-reported profeminist attitudes and behaviors and relating to self-esteem and social desirability would occur. 22 Ss were randomly assigned to either a 16-hr marathon group format or a 2-hr, 8-wk time-spaced group format. 12 additional Ss who took objective measures at the same time as 1 of the 2 groups acted as no-treatment controls. All experimental Ss significantly shifted toward more self-reported profeminist attitudes and behaviors both at posttesting and at follow-up. Two personality measures did not reveal any lasting changes. When compared with each other, Ss in the 2 time formats did not evidence any significant differences. When compared with control Ss, time-spaced Ss reported significantly more profeminist behavioral changes and an increase in self-esteem. Marathon Ss were significantly different from controls on a profeminist attitude measure (Attitudes Toward Women Scale). The purpose for which consciousness-raising groups have been formed was empirically supported by desired changes reported by Ss in relation to more profeminist attitudes and behaviors. Whether participation in consciousness-raising groups produces increases in self-esteem and decreases in the need for social approval is in need of further assessment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unconventional superconductivity and novel quantum order

Superconductors have many unusual properties not observed in normal metals. The superconducting state is attributed to the pairing of electrons. Conventional forms of superconductivity are produced by distortions in the underlying crystal structure of the material. Recently, it has become evident that not all forms of superconductivity can be explained in this way. The way pairing occurs has to be redressed in these materials. Of particular interest is the interplay between magnetism and superconductivity and the consequences this may have on pair formation.     

Formation mechanism of porous reaction-bonded silicon nitride with interconnected pores in the presence of MgO

In porous reaction bonded silicon nitride, whiskers normally grow in globular clusters as the dominant morphology and deteriorate the pore interconnectivity. However, the ceramic microstructure was significantly transformed with the addition of MgO; specifically, the morphology was modified to a combination of matte and hexagonal grains. Microstructural observation along with thermodynamic studies suggest that MgO interfered with the presence and nitridation of SiO_(g). Consequently, rather than being involved in the whiskers’ formation, surface silica instead reacted with volatile MgO to form intermediate products. Through these reactions, whisker formation was blocked, and a porous interconnected structure formed which was confirmed by 3D tomography. After heat-treatment at 1700 °C, β-Si₃N₄ crystallized in a glassy matrix containing magnesium. Resulting samples had an open-pore structure with porosity of 74–84 vol. %, and density of 0.48-0.75 g.cm^?3. Combination of high porosity and pore size of <40 μm led to compressive strengths of 1.1–1.6 MPa.     

Lattice imaging of structural defects in a chain silicate: The pyroxenoid mineral rhodonite

The pyroxenoid mineral rhodonite has been examined by electron diffraction and high-resolution lattice imaging. Planar defects parallel to (110) and (001) have been observed. The former are comparable to the (100) stacking faults frequently observed in the related mineral wollastonite, whereas the latter involve unit cell strips of the more complex pyroxmangite structure occasionally inserted into the parent rhodonite matrix.     

Effects of varying the amounts of dietary calcium on selenium metabolism in dairy calves

Influence of dietary Ca on Se metabolism was studied with 16 intact male Holstein calves averaging 86 kg. Calves were assigned randomly and fed one of four diets containing, .17, .67, 1.31, and 2.35% Ca at 3% of their body weight for 4 wk. The diets contained .062 ppm Se and .34% P. Four days prior to the end of the experiment, calves were dosed orally with radioactive 75Se. Dietary Ca had no significant effect on 75Se absorption. There was a slight curvilinear relationship between apparent 75Se absorption and dietary Ca intakes. Urinary excretion of 75Se and stable Se tended to decrease with increasing dietary Ca, but differences were not significant. No significant differences were found in concentration of 75Se in several tissues. Kidney and liver had the highest concentration with that in kidney being about four times that of liver. Apparent 75Se absorption was decreased 10 to 6%, respectively, in calves fed extremely low and high amounts of Ca, compared with those receiving the requirement (.67% Ca). These small reductions along with a small R2 suggest that dietary Ca probably is of little practical importance relative to Se metabolism in calves.