Diet and the lipid composition of adipose tissue in the young lamb

The changes in the lipid composition of the perirenal adipose tissue obtained from groups of lambs receiving either ewes' milk or a reconstituted low-fat milk powder have been studied during the first 8 days after birth. The triglycerides were further analysed by a stereospecific analytical procedure to obtain the intramolecular distribution of the fatty acids between the hydroxyl groups of the glycerol moeity. The percentage composition of the major lipid fractions in the perirenal adipose tissue from the naturally fed lambs remained similar to that of the adipose tissue obtained from the lambs at birth, but in the lambs receiving the artificial diet the relative concentration of the triglycerides was considerably reduced and that of the unesterified fatty acid and phospholipid fractions increased. At birth 18 :1 was the major fatty acid present in the triglyceride, unesterified fatty add and phospholipid fractions. Any polyunsaturated fatty acids were confined to the phospholipid fraction. Although there were negligible concentrations of the C18 polyunsaturated fatty acids, the C20 and C22 polyunsaturated fatty acids comprised some 20% of the fatty acids of the phospholipids. In the naturally fed lambs the concentration of 18: 2ω6 increased considerably during the 8 days after birth and there was a decrease in the concentration of 20 : 3ω9. In the artificially fed lambs the concentration of 20 : 3ω9 remained similar to that found at birth and there was no accumulation of 18 : 2ω6. In the triglycerides at birth 70–80% of 18 : 1-cis was in the 2-position and the saturated fatty acids were located mainly in the 1-and 3-positions. In both groups of lambs the concentration of 18 : 1-cis decreased and the concentration of 18 : 0 increased after birth. In the naturally fed lambs the increase in 18 : 0 occurred mainly in positions 1-and 3-but in the artificially fed lambs the concentration of 18 : 0 also markedly increased in position 2. The changes in concentration of 16 : 0 paralleled that of 18 : 0. In the naturally fed lambs the concentrations of 14:0, 18: 1-trans and 18 : 2ω6 which were probably of dietary origin increased considerably. 14 : 0 and 18 : 1 trans were concentrated largely in positions 1 and 3 whilst 18 : 2ω6 was concentrated mainly in position 2.     

Coordinated expression of beta 1 integrins and transforming growth factor-beta-induced matrix proteins in glomerulonephritis

Conti and Stühmer (1989. Eur. Biophys. J. 17:53-59) have measured the nonstationary shot noise in the gating current of a population of sodium channels. Here we present expressions for the autocovariance and variance of such noise from general Markov models of channel kinetics, based on the theoretical work of E. Frehland. We compare the predictions of the independent, two-state gating model used by Conti and Stühmer with a six-state model of sodium channel activation based on the work of Armstrong and Gilly (1979. J. Gen. Physiol. 74:691-711). We find that Conti and Stühmer's experiment would not be able to distinguish between these schemes. We describe experimental conditions under which better model discrimination would be possible.     

The positional distributions of fatty acids in the triacylglycerols and phosphatidylcholines of the intestinal and popliteal lymph and plasma of sheep

As part of a study of the contribution of the intestinal lymph lipoproteins and their lipid constituents to the plasma lipids in sheep, the positional distributions of the fatty acids in the triacyl-sn-glycerols and phosphatidylcholines in very low density/low density lipoprotein and high-density lipoprotein fractions were determined by stereospecific analysis procedures. The triacyl-sn-glycerols of these lipoprotein fractions in intestinal lymph did not differ appreciably in structure and resembled the plasma triacyl-sn-glycerols in the composition of positionsn-2 especially. However, there were appreciable amounts of the essential fatty acid, linoleic acid, in positionssn-1 andsn-3 of the triacylglycerols in lymph but not in plasma. This result is discussed in terms of the metabolism of the triacylglycerols of lymph after they enter the plasma as part of a mechanism for the conservation of essential fatty acids in ruminants. No differences of metabolic note were observed in the structures of the phosphatidylcholines between lipoprotein fractions and among tissues.     

The effect of femoral component position on the kinematics of total knee arthroplasty

In a laboratory study using seven fresh-frozen anatomic specimen knees, the effect of total knee arthroplasty on the three-dimensional kinematics of the patella, femur, and tibia were measured. Experiments were performed in the intact knee, after division of the anterior cruciate ligament (ACL), after total knee arthroplasty, and after 10 degrees internal rotation, 10 degrees external rotation, 5-mm medial shift, and 5-mm lateral shift of the femoral component on the femur. The presence of a high lateral ridge on the anterior surface of the femoral component effectively prevented patellar subluxation or dislocation, but displaced and tilted the patella medially. Internal rotation or medial displacement of the femoral component exaggerated this medial patellar displacement and shift. External rotation of the femoral component corrected it, except at flexion angles greater than 100 degrees, where the femur was shifted medially on the tibia and externally rotated 15 degrees. This combination produced a net 10-mm medial displacement of the patella relative to the tibia at 120 degrees knee flexion. Lateral placement of the femoral component compensated for the effect of the high lateral ridge and allowed more normal patellar tracking while allowing tibiofemoral motions similar to those seen after sectioning of the ACL. The kinematics of the patellofemoral and tibiofemoral joints were not reproduced with a total knee prosthesis that sacrifices the ACL. When using a prosthesis with a high lateral ridge, lateral placement of a femoral component prevented patellar dislocation and allowed patellar tracking patterns similar to those seen in the intact knee without further altering tibiofemoral motions.     

Qualitative and energy recovery potential analysis: plastic-derived fuel oil versus conventional diesel oil

Clean Technologies and Environmental Policy - Due to depleting fossil fuel sources, plastic-derived fuel oil (PDFO) has received much attention over the past decade as an alternative to...     

Silicalite-1 zeolite composite membranes

This review paper discusses the preparation of silicalite-1 zeolite membranes, the experimental procedures used for gas separation measurements and the results of single gas and gas mixture experiments. Silicalite-alumina composite membranes were prepared by an in-situ zeolite synthesis method using an alumina membrane tube with a 5-nm-pore-diameter, γ-alumina layer as a substrate. Single gas permeances of H₂, Ar, n-C₄H₁₀, i-C₄H₁₀ and SF₆ were measured and mixtures of H₂/i-C₄H₁₀ and H₂/SF₆ were separated to characterize the silicalite membrane. These measurements were made from 300 to 737 K. Transport through the silicalite membrane appeared to be controlled by molecular size and adsorption properties. Permeances of all components studied were activated, and activation energies ranged from 8.5 to 16.2 kJ/mol. The ratio of single gas permeances was as high as 136 for H₂/SF₆ and 1100 for H₂/i-C₄H₁₀ at 298 K. Separation selectivities at elevated temperatures were significantly above Knudsen diffusion selectivity and were larger than ratios of pure gas permeances at the same temperature. The largest permeance ratio for the separation of mixtures was 12.8 for H₂/SF₆ at 583 K. Separation selectivities were higher when a pressure drop was maintained across the membrane than when an inert sweep gas was used because of counter diffusion of the sweep gas.     

Replacing the ({beta}{alpha})-unit 8 of E.coli TIM with its chicken homologue leads to a stable and active hybrid enzyme

In order to investigate how structural modifications interferewith protein stability, we modified a (ß)-unit inE.coli triosephosphate isomerase (TIM), a typical (ß)-barrelprotein, assuming that the pseudosymmetrical ß-barrelcan be divided into eight successive loop/ß-strand/loop/-helixmotifs. We replaced the eighth (ß)-unit of E.coliTIM with the corresponding chicken (ß)-unit. The substitution,involving the replacement of 10 of the 23 residues of this (ß)-unit, was evaluated first by modelling, then experimentally.Modelling by bomology suggests how the amino add replacementsmight be accommodated in the hybrid E.coli/chicken TIM (ETCM8CHI).Both natural and hybrid recombinant TIMs, overproduced in E.coli,were purified to homogeneity and characterized as to their stabilityand kinetics. Our kinetic studies show that the modificationperformed here leads to an active enzyme. The stability studiesindicate that the stability of ETIM8CHI is comparable to thatof the wild type TIM.     

Targeted tumor cell internalization and imaging of multifunctional quantum dot-conjugated immunoliposomes in vitro and in vivo

Targeted drug delivery systems that combine imaging and therapeutic modalities in a single macromolecular construct may offer advantages in the development and application of nanomedicines. To incorporate the unique optical properties of luminescent quantum dots (QDs) into immunoliposomes for cancer diagnosis and treatment, we describe the synthesis, biophysical characterization, tumor cell-selective internalization, and anticancer drug delivery of QD-conjugated immunoliposome-based nanoparticles (QD-ILs). Pharmacokinetic properties and in vivo imaging capability of QD-ILs were also investigated. Freeze-fracture electron microscopy was used to visualize naked QDs, liposome controls, nontargeted QD-conjugated liposomes (QD-Ls), and QD-ILs. QD-ILs prepared by insertion of anti-HER2 scFv exhibited efficient receptor-mediated endocytosis in HER2-overexpressing SK-BR-3 and MCF-7/HER2 cells but not in control MCF-7 cells as analyzed by flow cytometry and confocal microscopy. In contrast, nontargeted QD-Ls showed minimal binding and uptake in these cells. Doxorubicin-loaded QD-ILs showed efficient anticancer activity, while no cytotoxicity was observed for QD-ILs without chemotherapeutic payload. In athymic mice, QD-ILs significantly prolonged circulation of QDs, exhibiting a plasma terminal half-life ( t 1/2) of approximately 2.9 h as compared to free QDs with t 1/2 < 10 min. In MCF-7/HER2 xenograft models, localization of QD-ILs at tumor sites was confirmed by in vivo fluorescence imaging.     

Effects of contaminant metal ions on precipitation recovery of rare earth elements using oxalic acid

Solution equilibrium calculations were performed in this study to understand the impact of contaminant metal ions on the precipitation efficiency of selected ra...