Effects of diffusible products of peroxidation of rat liver microsomal lipids

The effects on cellular structures of products of peroxidation of rat liver microsomal lipids were investigated. A system containing actively peroxidizing liver microsomal fraction was separated from a revealing or target system by a dialysis membrane. The target system, contained in the dialysis tube, consisted of either intact cells (erythrocytes) or subcellular fractions (liver microsomal fraction). When liver microsomal fractions were incubated with NADPH (or an NADPH-generating system), lipid peroxidation, as measured by the amount of malonaldehyde formed, occurred very rapidly. The malon-aldehyde concentration tended to equilibrate across the dialysis membrane. When the target system consisted of erythrocytes, haemolysis occurred abruptly after a lag phase. The lysis was greatly accelerated when erythrocytes from vitamin E-deficient rats were used, but no haemolysis was observed when erythrocytes from vitamin E-treated rats were used. When, in the same system, freshly prepared liver microsomal fractions were exposed to diffusible factors produced by lipid peroxidation, the glucose 6-phosphatase activity markedly decreased. A similar decrease in glucose 6-phosphatase activity, as well as a smaller but significant decrease in cytochrome P-450, was observed when the target microsomal fractions were exposed to diffusible factors derived from the peroxidation of liver microsomal lipids in a separate preincubation step. These and additional experiments indicated that the toxicological activity is relatively stable. Experiments in which the hepatic microsomal fractions destined for lipid peroxidation contained radioactively labelled arachidonic acid, previously incorporated into the membranes, showed that part of the radioactivity released from the microsomal fraction into the incubation medium entered the dialysis tube and was recovered bound to the constituents of the microsomal fractions of the target system. These results indicate that during the course of the peroxidation of liver microsomal lipids toxic products are formed that are able to induce pathological effects at distant loci.     

Disturbance of lymphocyte circulation byPseudomonas aeruginosa infection in oxazolone-sensitized mice

Pseudomonas aeruginosa infection depresses contact sensitivity to oxazolone in mice. To test whether an altered lymphocyte circulation plays a role in this depression⁵¹Cr-labeled lymphocytes fromP. aeruginosa-infected and oxazolone-sensitized donors were injected intravenously into infected and sensitized recipients, and the radioactivity uptake of several organs was determine. The controls consisted of normal mice receiving labeled lymphocytes from normal donors. While the radioactivity recovered from the liver, spleen, and mesenteric lymph nodes was similar in the test and the control group, significantly more radioactivity was recovered from the draining lymph nodes of infected and sensitized recipients. The concentration of labeled lymphocytes from sensitized donors in the draining lymph nodes of sensitized recipients was 18% greater than that of the controls but 31% lower than that of infected and sensitized animals receiving cells from infected and sensitized donors.P. aeruginosa infection enhances lymphocyte entrapment within the draining lymph nodes of oxazolone-sensitized mice.     

Interaction of charged lipid vesicles with planar bilayer lipid membranes: Detection by antibiotic membrane probes

A technique has been developed for monitoring the interaction of charged phospholipid vesicles with planar bilayer lipid membranes (BLM) by use of the antibiotics Valinomycin, Nonactin, and Monazomycin as surface-charge probes. Anionic phosphatidylserine vesicles, when added to one aqueous compartment of a BLM, are shown to impart negative surface charge to zwitterionic phosphatidylocholine and phosphatidylethanolamine bilayers. The surface charge is distributed asymmertically, mainly on the vesicular side of the BLM, and is not removed by exchange of the vesicular aqueous solution. Possible mechanisms for the vesicle-BLM interactions are discussed.     

Water permeability and lipid composition of toad urinary bladder: The influence of temperature

Summary The water diffusional permeability, its activation energy and the lipid composition were studied in urinary bladders from toads adapted to different temperatures. It was observed that the unidirectional water flux greatly depends on the temperature at which the experiments are performed. This dependence is greater in the animals adapted to higher temperatures. Toads adapted to cold show strong reduction in the activation energy for water diffusion permeability (from 11.4±1.9 kcal·mol^–1 to 4.4±1.1 kcal·mol^–1) and an increase of 30% in the amount of total lipids from bladder epithelial cells. There were no significant changes in the phospholipid/cholesterol ratio, composition of the paraffinic chains or protein concentration between toads adapted to both temperatures. The possibility that water translocates through the mucosal border of the toad bladder by partitioning in the polar zone and diffusioning between the hydrocarbon chains of the membrane lipids and that cold adaptation would induce a stronger packing of lipids in the membrane is discussed.     

Norditerpene dilactones from Podocarpus saligna

Rimuene and nubigenol have been identified in Podocarpus saligna for the first time, and the structures of three new norditerpene dilactones, salignones K, L and M, isolated from this species have been elucidated.     

An automated differential thermal and potentiometric titration apparatus for binding studies

A differential pH-termal titration apparatus is described which can detect pH differences with a sensitivity of ±0.0001 pH units and a thermal sensitivity of ±0.00002°C at a time constant of 0.1 s. With a reaction which yields 1 kcal mol⁻¹, the current system can detect concentrations as low as 4×10⁻⁶ M or, in a 2 ml volume, a total amount of 40 nmol. With a time constant of 0.1 s, the sensitivity is 20±4 μ°C. The experimental protocol is specified by a microprocessor and three modes of operation are possible: titration at constant rate of reagent addition, titration at variable rates of addition so that the contents of both cells are at either constant pH or at a constant temperature and variable rate when a rate of change is specified. Experimental data are collected in files, corrected for heat loss, initial baseline drift, and changes in volume. The final corrected from the standardized run of 0.01338 M HCl in 0.2 M KCl at 25°C calibrate the pH scale yielded the calorimetric conversion constants and pK_w which are calculated and stored for subsequent corrections for the titration of an unknown acid or the measurement of bindin constants and heats.     

Efficacy of different types of aerobic exercise in fibromyalgia syndrome: a systematic review and meta-analysis of randomised controlled trials

Introduction  

The efficacy and the optimal type and volume of aerobic exercise (AE) in fibromyalgia syndrome (FMS) are not established. We therefore assessed the efficacy of different types and volumes of AE in FMS.