Liver parenchymal cells differ from the fat-storing cells in their lipid composition

The neutral lipid and phospholipid compositions of purified sinusoidal (fat-storing, endothelial and Kupffer) cells, parenchymal cells and liver homogenates were determined by thin layer chromatography. In addition, the retinoid content of the same purified cell populations was determined by high performance liquid chromatography. From each cell type, both a lipid droplet fraction and a pellet fraction (containing the majority of the remaining cell organelles) were prepared by differential centrifugation. Electron microscopic analysis showed that lipid droplets isolated from fat-storing cells were larger (up to 8 μm) than those isolated from parenchymal cells (up to 2.5 μm). Moreover, the parenchymal lipid droplets seemed to be surrounded by a membranous structure, while the fat-storing lipid droplets seemed not to be. Both fat-storing and parenchymal cells contained high concentrations of neutral lipids, 57.9 μg and 71.0 μg/10⁶ cells, respectively, while endothelial and Kupffer cells contained only 8.6 μg and 13.8 μg/10⁶ cells of neutral lipids, respectively. Sixty-five percent of fat-storing cell lipid droplet fractions comprised esters of retinol and cholesterol. This combined ester fraction contained mainly retinyl esters. In addition, considerable quantities (20%) of triglycerides were present. Parenchymal cell lipid droplet fractions comprised triglycerides (62%) and cholesteryl esters (up to 30%). The pellet fractions prepared from all four cell types consisted mainly of cholesterol (41–67%) and free fatt acids (20–28%). The phospholipid content was much higher in parenchymal cells than in the sinusoidal liver cell types. The relative proportions of the four major phospholipid classes were comparable in all liver cell types analyzed. It is concluded that parenchymal cell lipid droplets comprised mainly triglycerides and cholesteryl esters, which is in agreement with the function of parenchymal cells in lipid metabolism. Fat-storing cell lipid droplets consisted of retinyl esters and triglycerides, which correlates well with their function in retionid storage and metabolism.     

Influence of the molecular weight of ionenes on the cobaltphthalocyanine-catalysed autoxidation of mercaptoethanol

In order to study the promoting effect of polycations on the cobalt(II)phthalocyanine-tetrasodiumsulphonate (CoPc(NaSO₃)₄)-catalysed autoxidation of thiols, it is imperative to know the molecular weight dependence of the polymer. Monodisperse oligomers can often supply a lot of information. To elecidate the mechanism of the promoting effect of 2,4-ionene, a poly(quaternary ammonium)salt, on the CoPc(NaSO₃)₄-catalysed autoxidation of 2-mercaptoethanol, a series of monodisperse 2,4-ionene oligomers were prepared. Trimeric 2,4-ionenes, containing two quaternary ammonium groups separated by four methylene groups, showed a high co-catalytic activity, and active Co-aggregates were detected with visible light spectroscopy. The spectroscopic behaviour was in close agreement with that of high molecular 2,4-ionene/CoPc(NaSO₃)₄ complexes. In order to achieve this aggregation several oligomeric ionenes have to act concertedly. If the distance between the ionic sites is short the trimer acts as a simple salt in stablizing the aggregates. With respect to the catalytic activity the optimum polycation/catalyst ratio, expressed as the N⁺/Co ratio, decreased with increasing chain lenght and reached a constant level of 50 at a 2,4-ionene nonamer. For the trimers and pentamers this ratio is affected by the type of end-group. All synthesized 2,4-ionene oligomers exhibited excellent co-catalytic properties at the optimum N⁺/Co ratio, with maximum turnover frequencies of 4600 mol thiol/(mol Co s), i.e. 50 times higher than those obtained for the polymer-free system. In the case of monodisperse 2,4-ionene pentamer with bromo end-groups, double Michaelis–Menten kinetics were observed, as also was exhibited by high molecular weight ionene.     

STABLE ALGORITHMS FOR THE STATE SPACE MODEL

Abstract. Numerically stable algorithms are developed for filtering, likelihood evaluation, generalized least squares computation and smoothing where data are generated by a state space model. The algorithms handle diffuse initial states in a numerically safe way. Singular innovation covariance matrices, such as those which arise in series with missing values, are dealt with. The algorithms generalize stable algorithms for ordinary least-squares computations.     

The use of hybrid computers for system-parameter estimation

This paper is devoted to the question in what way system-parameter estimation problems can be solved by means of hybrid equipment and what approaches are best suited for such problems.The combination of an analog model of the system under study and the digital computer taking care of the adjustment of that model is still an attractive scheme, in spite of the strong competition due to the rapid development of purely digital techniques.Advantages and problems are pointed out. Some illustrative examples are summarized.     

Extraction and fractionation of wheat flour proteins

Extraction of wheat flour with 1.5% sodium dodecyl sulphate (SDS) solution dissolved 65–67% of the total flour nitrogen. The SDS-insoluble proteinaceous material was separated into glycoproteins-I, II and III by ultracentrifugation. Part of the SDS-soluble proteinaceous material was precipitated by addition of ethanol and separated into glycoproteins-IV, glutenins and globulins. The rest of the dissolved proteinaceous material was separated into glycoproteins-V, gliadins, glycoproteins-VI, and albumins by (NH₄)₂SO₄-precipitation and gel filtration chromatography.     

Calculating power in analysis of variance.

Presents an overview of procedures for calculating power of the F test under 3 models of ANOVA (fixed effects, random effects, and mixed effects). A comparison of power of tests on fixed and random factors shows the latter to have substantially lower power. Consequences for designing experiments and for interpreting experimental results are discussed, and the simplicity with which power calculations are done is emphasized. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)