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 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.     

Expressed emotion and attributions in the carers of patients with Alzheimer's disease: The effect on carer burden.

Burden of care, expressed emotion (EE), causal attributions, and salivary cortisol were assessed in 100 carers of patients with Alzheimer's disease. Forty-one carers were rated high EE, which was associated with higher scores of carer distress and strain, and greater reports of noncognitive features in the patient, but not with cortisol levels. High EE carers made more attributions personal to, and controllable by, the patient for negative events. Critical carers made more attributions of the patient's behavior that was idiosyncratic. Warmth toward the patient was associated with the opposite of this pattern. Overinvolved carers made attributions of the patient's behavior to causes external to the patient and internal to themselves. Cortisol levels were associated with self-reports of strain and distress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Structural and thermodynamic characterization of the interaction of the SH3 domain from Fyn with the proline-rich binding site on the p85 subunit of PI3-kinase

The interaction of the Fyn SH3 domain with the p85 subunit of PI3-kinase is investigated using structural detail and thermodynamic data. The solution structure complex of the SH3 domain with a proline-rich peptide mimic of the binding site on the p85 subunit is described. This indicates that the peptide binds as a poly(L-proline) type II helix. Circular dichroism spectroscopic studies reveal that in the unbound state the peptide exhibits no structure. Thermodynamic data for the binding of this peptide to the SH3 domain suggest that the weak binding (approximately 31 microM) of this interaction is, in part, due to the entropically unfavorable effect of helix formation (delta S0 = -78 J.mol-1.K-1). Binding of the SH3 domain to the intact p85 subunit (minus its own SH3 domain) is tighter, and the entropic and enthalpic contributions are very different from those given by the peptide interaction (delta S0 = +252 J.mol-1.K-1; delta H0 = +44 kJ.mol-1). From these dramatically different thermodynamic measurements we are able to conclude that the interaction of the proline-rich peptide does not effectively mimic the interaction of the intact p85 subunit with the SH3 domain and suggest that other interactions could be important.     

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.     

Fatty acid and sensory characteristics of beef from three biological types of cattle grazing cool-season forages supplemented with soyhulls

Over two consecutive years, the effects of allocating divergent biological types of cattle (n=107) to fescue pasture without supplementation, or fescue or orchardgrass pasture with soyhull supplementation on chemical, fatty acid and sensory characteristics were investigated. Cattle from the two supplemented treatments produced beef that had increased (P<0.05) percentage lipid and decreased (P<0.05) polyunsaturated and n-3 fatty acids compared to the control. However, the n-6 to n-3 ratio was still less than four in beef from the supplemented cattle. Additionally, supplementation did not decrease (P>0.05) the CLA present in the longissimus, which can commonly occur when forage-fed cattle are supplemented concentrates. Although supplementation did not impact (P>0.05) Warner-Bratzler shear force or tenderness, supplementation of soyhulls reduced (P<0.05) the grassy flavor intensity of rib steaks when compared to the control. Biological type did not have a significant influence on most traits analyzed in this study. These results suggest that supplementation of soyhulls to cattle grazing forage can reduce grassy flavor intensity without decreasing CLA proportions, but can reduce the n-3 fatty acid proportions present in the longissimus.     

Twin fiber grating tunable dispersion compensator

A new tunable dispersion compensator that does not suffer from higher order dispersion is reported. The device consists of two quadratically chirped fiber Bragg gratings, each with linear strain actuators. The module has a tuning range of 500 ps/nm and a bandwidth of 0.5 nm. In a 40-Gb/s return-to-zero system, the dispersion penalty tolerance is extended from 100 to 600 ps/mm     

The use of site surveys in the collection of recreation data,with particular reference to the Congleton district of Cheshire

The provision of countryside recreation facilities at a local level is likely to receive increasing attention during the next decade. As an integral part of the assessment of the quality of present provision within the Congleton District of Cheshire (U.K.) five site surveys were made. Each site provides different facilities for recreation and interview questions were designed to investigate the background of the visitors and the nature of the interplay between site and visitor. The analysis of answers attempts to illustrate those aspects of this interrelationship which may be important during the consideration of future provision of recreation sites and their management.