The potentiation of the histamine release induced by adenosine in mast cells from guinea pig lung and heart: Sharp dependence on the time of preincubation

We studied here the effect of a wide range of adenosine concentration and time of preincubation, on the histamine release induced in the guinea pig mast cells by different stimulus. Adenosine (10(-5)-10(-3) M) potentiated the histamine release induced by antigen in the guinea pig heart (isolated and dispersed tissue) and lung mast cells but not induced by ionophore A23197. The potentiation caused by adenosine (10(-4) M) was maximum after 1-3 min of preincubation and is probably an extracellular effect since it was not avoided by dipyridamol (3 x 10(-7)-10(-6) M) that inhibit the uptake of adenosine. Similar potentiation was also produced by the adenosine mimetic 2-chloroadenosine (10(-5) M) and both effects were inhibited by 8-phenyltheophylline indicating an effect on the type A receptors. It is suggested that the adenosine potentiation may not be related to changes on the cyclic AMP levels. (C) 2000 Academic Press.

Differential regulation of the release of tumor necrosis factor-alpha and of eicosanoids by mast cells in rat airways after antigen challenge

Background: Rat trachea display a differential topographical distribution of connective tissue mast cells (CTMC) and mucosal mast cells (MMC) that may imply regional differences in the release of allergic mediators such as tumor necrosis factor-alpha (TNF-alpha) and eicosanoids.Aim: To evaluate the role of CTMC and MMC for release of TNF-alpha and eicosanoids after allergenic challenge in distinct segments of rat trachea.Materials and methods: Proximal trachea ( PT) and distal trachea (DT) from ovalbumin (OVA)-sensitized rats, treated or not with compound 48/80 ( 48/80) or dexamethasone, were incubated in culture medium. After OVA challenge, aliquots were collected to study release of TNF-alpha and eicosanoids.Results: Release of TNF-alpha by PT upon OVA challenge peaked at 90 min and decayed at 6 and 24 h. Release from DT peaked at 30-90 min and decayed 6 and 24 h later. When CTMC were depleted with 48/80, OVA challenge exacerbated the TNF-alpha release by PT at all time intervals, while DT exacerbated TNF-alpha levels 6 and 24 h later only. Dexamethasone reduced TNF-alpha production after 90 min of OVA challenge in PT and at 3 and 6h in DT. OVA challenge increased prostaglandin D-2 in DT and leukotriene B-4 in both segments but did not modify prostaglandin E-2 and leukotriene C-4 release.Conclusion: OVA challenge induces TNF-alpha release from MMC, which is negatively regulated by CTMC. The profile of TNF-alpha and eicosanoids depends on the time after OVA challenge and of the tracheal segment considered.

Density, heat capacity and thermal conductivity of liquid egg products

Density, heat capacity and thermal conductivity of liquid egg products, such as egg white, egg yolk, whole egg and various white and yolk blends, were determined as affected by temperature and water content ranging from 273 to 311 K and 51.8 to 88.2% (mass), respectively. Polynomial models fitted the experimental data very well, showing a linear relationship both for temperature and water content. (c) 2005 Published by Elsevier Ltd.

Rhodocyclus gelatinosus biomass for egg yolk pigmentation

Biomass of the photosynthetic bacterium Rhodocyclus gelatinosus was used at different levels in laying hens' rations as a xanthophyll source. Sixty-four hens were used in the experiment that investigated the effects of different biomass concentrations on weight gain, egg production, egg weight, and yolk color as compared with a control group that received no biomass supplementation in the ration. Yolk color was scored by means of a color fan. All concentrations tested were able to provide yolk color scores higher than those provided by the control group. The pigment deposition began after 24 h of administration and reached a plateau around the twentieth day. Each increase in the supplementation level led to an additional increase on yolk color scores. Yolk colors of all treatments that received R. gelatinosus biomass differed significantly from the control group and from each other, corroborating that the increase in the biomass supplementation had a positive effect on color increase. Body weight loss occurred in all treatments. Egg production did not increase with the biomass addition, while a significant increase in egg weight was observed in the treatments that received the product.

Magnetic field release of trapped charges in poly(fluorenylenevinylene)s

We have measured the effect of an applied magnetic field on the current through thin films of two different organic conjugated polymers that have previously shown to exhibit magnetoresistance, poly(9,9-dioctyl-1,4-fluorenylenevinylene) and poly(9,9-dioctyl-2,7-fluorenylenevinylene). The results show that the magnetic field releases trapped charges from inside the material and enhances the current. We have also performed optical absorption experiments on these polymer films under applied voltage and magnetic field. The results show that the magnetic field produces a change in the optical absorption in the low-energy range associated with deep traps and only under conditions when these traps are likely charged. These two results provide a strong case for the release of trapped charges caused by the magnetic field as being the cause of the magneto resistance in these polymers and possibly in other organic materials where magnetoresistance was recently observed. (c) 2007 Elsevier B.V. All rights reserved.

Viscoelasticity of frozen/thawed egg yolk as affected by salts, sucrose and glycerol

Based on dynamic rheological measurements, sucrose, glycerol and magnesium chloride (MgCl2) prevented egg yolk gelation at concentrations of 2% and higher, These additives showed improved cryoprotectant effects as their concentrations were increased, Sodium chloride (NaCl) at higher than 2% also prevented gelation but at 10%, it caused a considerable increase in viscosity of unfrozen yolk, Calcium chloride (CaCl2) showed an opposite effect, promoting protein coagulation before freezing, Samples with 2% CaCl2 gelled completely after 36h at -24 degrees C, Before freezing, potassium chloride (KCl) in the range 2-10% had an effect similar to that of NaCl, However, after freezing its effect changed, Yolk with 2% KCl, frozen 36h at -24 degrees C, showed very elastic behavior.

Similar anxiolytic-like effects following intra-amygdala infusions of benzodiazepine receptor agonist and antagonist: Evidence for the release of an endogenous benzodiazepine inverse agonist in mice exposed to elevated plus-maze test

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Selection of radio transmitter and attachment method for post-release monitoring of captive-bred reintroduced Red-billed Curassow Crax blumenbachii, Brazil

Long-term monitoring of reintroduced individuals is a central component of many endangered species reintroduction programs. Radio-telemetry techniques are rarely used to monitor reintroduced captive-bred Cracids and few data exist regarding possible adverse effects of radio-tagging Cracids. In this study, we identify an appropriate radio transmitter design and develop a suitable attachment method that minimizes anthropogenic influence and enables long-term, post-release monitoring (2-3 years) of reintroduced captive-bred Red-billed Curassows in the Brazilian Atlantic Rainforest. We also review studies about the effects of different VHF radio transmitter models on survival, reproduction, behavior, and physiology of Galliformes.