Effects of ruminal doses of sucrose, lactose, and corn starch on ruminal fermentation and expression of genes in ruminal epithelial cells.

The objective was to evaluate effects of a ruminal dose of sucrose, lactose, and corn starch on ruminal fermentation and expression of genes in ruminal epithelial cells. Six ruminally cannulated nonlactating nonpregnant Holstein cows (body weight=725±69.6kg) were assigned to treatments in a 3×3 Latin square design with 7-d periods; 1d for data and sample collection followed by a 6-d washout period. Cows were fed a diet containing whole-crop barley silage and dry ground corn, and dietary neutral detergent fiber and crude protein contents were 41.8 and 13.2% [dry matter (DM) basis], respectively. Treatment was a pulse-dose of sucrose, lactose, and corn starch (3.0, 3.0, and 2.85kg of DM, respectively; providing similar amounts of hexose across the treatments) through the ruminal cannulas. All treatments were given with alfalfa silage (1.75kg DM) to prevent acute rumen acidosis. Rumen pH was continuously monitored, and rumen fluid was sampled at 0, 30, 60, 90, 120, 150, and 180min after the dose. In addition, ruminal papillae were sampled from the ventral sac at 180min after the dose. Ruminal dosing with sucrose and lactose, compared with corn starch, increased ruminal total volatile fatty acid concentration and molar proportion of butyrate from 60 to 180min after the dose, and expression of genes for sodium hydrogen exchanger isoforms 1 and 2, and ATPase isoform 1 in ruminal epithelial cells. Ruminal dosing with sucrose, compared with lactose and corn starch, decreased rumen pH from 120 to 180min after the dose and molar proportion of acetate in ruminal fluid from 60 to 150min after the dose, and increased molar proportion of propionate in ruminal fluid from 60 to 150min, and expression of genes involved in butyrate metabolism (3-hydroxy-3-methylglutaryl-coenzyme A synthase isoform 1) and anion exchange across ruminal apical cell membrane (putative anion transporter isoform 1). These results suggest that replacing dietary starch with sugars may affect ruminal fermentation and metabolism regulating intracellular pH and fermentation acid absorption in ruminal epithelial cells, and that these effects can be greater for sucrose than lactose.

Research note: methodology for high-quality RNA extraction from poultry whole blood for further gene expression analysis.

1. There are no published methods for RNA isolation from avian whole blood where nucleated red blood cells prevent the use of established mammalian protocols. The aim of this study was therefore to develop a protocol for total RNA extraction using avian whole blood by defining the effect of anticoagulants and sample purification protocols on RNA yield and quality. 2. Blood collections from the cutaneous ulnar or medial metatarsal veins of birds yielded adequate blood volume (2-3 ml) draws. The experiment was a 2 × 2 × 3 factorial arrangement of treatments, with two levels of DNase (0 and TURBO DNA-free Kit), two levels of Cleanup (0 and RNeasy MinElute Cleanup Kit), and three anticoagulants (no anticoagulant, EDTA, or sodium citrate). 3. RNA was isolated successfully by adding TRIzol LS to 0.25 ml of chicken whole blood at 3:1 ratio. From 0.125 ml of avian whole blood, 2-3 µg of RNA with RNA integrity number values of 7.75 was successfully isolated with the TRIzol LS extraction and an RNeasy MinElute Cleanup Kit. 4. This reliable protocol can be used to extract high yield and quality of total RNA from a small amount of whole blood.

Polysulfone-ZrO(2) surface interactions. The influence on formation, morphology and properties of zirfon-membranes.

The interaction between polysulfone and ZrO(2) particles is studied as a function of the particle sintering temperature in order to understand the role of ZrO(2) on the formation, morphology, and properties of organo-mineral composite membranes. The adsorption between the sintered ZrO(2) and the constituents of polysulfone, 2,2-diphenylpropane and diphenyl sulfone, is investigated using high-pressure liquid chromatography. The influence of the polymer-ZrO(2) interaction on the flow behavior of the casting suspension is registered via viscoelastic measurements. The organo-mineral composite membranes are formed by immersion precipitation in water, and the resulting membrane morphology is analyzed using high-resolution SEM. The zirconia concentration in the top-layer of the composite structure is determined by XPS. Finally, the link between the polymer-filler interactions, the membrane formation process, and the resulting membrane structure and properties is established.

Multi length scale analysis of the microstructure in sticky sphere dispersions during shear flow.

The effect of shear flow on the microstructure in a weakly aggregated suspension is investigated. Monodisperse small silica particles with a grafted layer of 1-octadecanol are dispersed in n-tetradecane, yielding a thermoreversible sticky sphere model suspension. A combination of small angle light scattering and ultra small and small-angle X-ray scattering techniques have been used, in situ and time resolved, to study the flow-induced anisotropy of the microstructure. In this manner, the length scales from the single particle size to that of the spatial organization of the aggregates can be covered. Harmonic expansion of the structure factor demonstrates that anisotropy develops in the microstructure on all relevant length scales. Possible real space interpretations of the scattering information are discussed in conjunction with implications for the nonlinear rheological behavior.

Stress jumps on weakly flocculated dispersions: steady state and transient results.

Weakly flocculated, thixotropic suspensions have been investigated by means of fast stress jump experiments. With a suitable procedure, reliable stress relaxation data could be collected starting 20 ms after cessation of flow. This technique has been used to determine the elastic and hydrodynamic contributions to the shear stress. Steady state as well as transient flows have been studied for suspensions containing either fumed silica or carbon black particles in a Newtonian medium. In both systems, the elastic stress totally dominates the response at low shear rates and consequently also the apparent yield stress. This stress contribution becomes negligibly small at high shear rates. The hydrodynamic contribution to the viscosity has finite limits at both the low and high shear rate ends. The data are relevant for testing rheological models. As an illustration, it is shown that the data agree qualitatively with the model proposed by Potanin et al. (J. Chem. Phys. 102 (14) (1995) 5845-5853).

Structure and rheology during shear-induced crystallization of a latex suspension.

Microstructure and rheology of a concentrated sterically stabilized colloidal suspension undergoing flow-induced ordering was studied by combined small-angle x-ray scattering and rheometry. This system is known to form bundlelike structures at high stress values in continuous shear flow. Under large amplitude oscillatory flow, hexagonal close-packed crystalline domains are formed within 1 sec of the inception of shear. In the intermediate range of frequencies and amplitudes, a nearly perfect hexagonally close-packed layer structure was observed after the cessation of flow. Lower frequencies or stress amplitudes resulted in polycrystals and, on the other hand, high frequencies or stress amplitudes led to partial melting of the layered structure. During the oscillatory flow, the intensity of the Bragg peaks showed pronounced oscillations.

Flow-Induced Anisotropy in Mixtures of Associative Polymers and Latex Particles.

The effect of associative polymers on the structure and rheological behavior of colloidal suspensions is discussed. Adding associative polymer is known to increase the viscosity of the suspensions. At high shear rates the increase is close to what could be expected on the basis of the hydrodynamic effects of the added polymer. At low shear rates the viscosity increases much more. Small-angle light scattering (SALS) during flow is used here to investigate the underlying structural mechanisms. The SALS patterns indicate that the associative polymer changes the particulate structure: characteristic butterfly patterns appear even at relatively low particle volume fractions. They are not present in the suspensions without associative polymer. The patterns indicate that fluctuations in particle concentration are more pronounced in the flow direction than in the vorticity direction and that anisotropic particulate structures with an orientation along the vorticity direction develop. The evolution of their characteristic length scale during flow has been followed over time. Changing the hydrophilic part of the polymer from polyacrylamide to polyacrylic acid induces stronger associative interactions. In the suspensions this results in a reduction of the relative viscosity rather than an increase. The difference in degree of associativity between the polymers also has an effect on the SALS patterns in the suspensions both at rest and during flow. The rheology as well as the SALS suggest the presence of a strong polymer network in the second system. The competition between adsorption of the associative polymer on the particles with the intermolecular associations between the polymer chains seems to be responsible for the observed differences. Copyright 2000 Academic Press.

Large-Scale Bundle Ordering in Sterically Stabilized Latices.

Time-resolved small-angle light scattering and linear conservative dichroism measurements are presented for concentrated, sterically stabilized, aqueous latices under simple shear flow. At low stress levels, flow causes a mild distortion of the liquid-like structure in colloidally stable dispersions, which is quite well understood. In this paper flow-induced structures are investigated in concentrated dispersions when the system is brought far from equilibrium by means of hydrodynamic forces. At high stress levels various structural changes have been predicted by numerical simulation, among others string phases oriented in the flow direction. Here, experimental results are reported on a bundle-like ordering in very dense systems, which involves a length scale much larger than that of a single string of particles. Two latices, with different particle sizes and different thicknesses of the stabilizing layer, are compared. The occurrence of the bundle-like ordering is related to the rheological behavior: it causes a significant decrease in viscosity. It is shown that the presence of this phase results in a structural hysteresis, which explains a thixotropic behavior that is encountered in some stable colloidal suspensions. Also the relaxation behavior of the bundle-like phases has been studied. Interparticle forces are found to have a very strong effect on the relaxation time scales. Copyright 1999 Academic Press.

In vitro experiments with an injection technique for cup fixation in total hip arthroplasty.

A new technique has been developed to position the cup rigidly into the acetabulum during total hip joint replacement. After positioning the flanged cup on the acetabulum by means of screws, a low-viscosity cement is injected through a hole in the rim of the cup. A comparison with the standard cementing technique was made on the basis of in vitro experiments. For this purpose a mold was constructed to produce castings simulating the human acetabulum. The distribution of the cement, the pressure developed in the acetabulum, and the penetration of the cement are compared for the two cementing techniques.