Guava flavored whey-beverage processed by cold plasma: Physical characteristics, thermal behavior and microstructure

The present study aimed to compare the physicochemical (pH), physical (rheology parameters and particle size), microstructure (optical microscopy) and thermal properties (differential scanning calorimetry) of guava flavored whey-beverages submitted to cold plama technology in different processing time (5, 10, and 15 min) and gas flow (10, 20, and 30 mL min^-1) conditions with a conventional pasteurized product. Whey beverages treated by cold plasma presented higher pH values, lower consistency and lower viscosity, and a flow behavior index similar to Newtonian fluids. Milder cold plasma conditions resulted in whey beverages with higher pH, lower viscosity and consistency, and similar particle distribution and microstructure compared to the pasteurized product. In contrast, more severe processing conditions resulted in a higher particle surface area ([D 3,2]) and smaller particles (~10 μM), due to the decrease in the number of larger particles (1000 μM), cell rupture, the formation of cell fragments, and higher viscosity and consistency. The treatments did not affect the thermal properties (enthalpy and bound water) of any sample.

Effects of the PAF receptor antagonist UK74505 on local and remote reperfusion injuries following ischaemia of the superior mesenteric artery in the rat

The effects of the long lasting and potent PAF receptor antagonist UK74505 were assessed on the local and remote injuries following ischaemia and reperfusion (I/R) of the superior mesenteric artery (SMA) in rats. In a severe model of ischaemia (120 min) and reperfusion (120) injury, in addition to the local and remote increases in vascular permeability and neutrophil accumulation, there was significant tissue haemorrhage, blood neutropenia, systemic hypotension and elevated local and systemic TNF-alpha levels. Post-ischaemic treatment with the selectin blocker fucoidin (10 mg kg(-1)) prevented neutrophil accumulation in tissue and, in consequence, all the local and systemic injuries following severe I/R. Treatment with an optimal dose of UK74505 (1 mg kg(-1)) also reversed local and remote neutrophil accumulation, increases in vascular permeability and intestinal haemorrhage. UK74505 partially inhibited blood neutropenia and reperfusion-induced hypotension. Interestingly, both fucoidin and UK74505 prevented the local, but not systemic, increases of TNF-alpha levels following severe I/R injury, demonstrating an important role of migrating cells for the local production of TNF-alpha. However, the results do not support a role for PAF as an intermediate molecule in the production of systemic TNF-alpha. The beneficial effects of UK74505 and other PAF receptor antagonists in models of I/R injury in animals and the safety of UK74505 use in man warrant further investigations of the use of this drug as preventive measure for I/R injury in humans.

Effects of a BLT receptor antagonist on local and remote reperfusion injuries after transient ischemia of the superior mesenteric artery in rats

Reperfusion of ischemic vascular beds may lead to recruitment and activation of leukocytes, release of mediators of the inflammatory process and further injury to the affected vascular bed and to remote sites. Neutrophils appear to play a major role in the pathophysiology of reperfusion injury. Amongst inflammatory mediators shown to activate neutrophils and induce their recruitment in vivo, much interest has been placed on the role of leukotriene (LT)B(4). Here, we have assessed the effects of the BLT receptor antagonist (+)-1-(3S, 4R)-[3-(4-phenyl-benzyl)-4-hydroxy-chroman-7-yl]-cyclopentane carboxylic acid (CP 105,696) in a model of neutrophil-dependent ischemia and reperfusion injury in the rat. The superior mesenteric artery was isolated and ischemia was induced by its total occlusion for 30 min. After 30 min of reperfusion, injury was assessed by evaluating the extravasation of Evans blue, an index of vascular permeability, and the levels of myeloperoxidase, an index of neutrophil accumulation, in the intestine, mesentery and lung. The neutrophil-dependence of the local (intestine and mesentery) and remote (lung) injury was confirmed by using fucoidin, a selectin blocker, and WT-3, an anti-CD18 monoclonal antibody. Post-ischemic treatment with CP 105,696 dose-dependently inhibited vascular permeability and neutrophil accumulation in the intestine and mesentery. CP 105,696 also blocked the vascular permeability changes, but not neutrophil accumulation, in the lungs after reperfusion injury. Virtually identical results were obtained with another BLT receptor antagonist, 1-(5-ethyl-2-hydroxy-4-(6-methyl-6-(1H-tetrazol-5-yl)-heptoxy++ +)-phenyl )ethanone (LY255283). Our results suggest that post-ischemic treatment with BLT receptor antagonists may inhibit local and remote ischemia and reperfusion injury by blocking both the accumulation and/or activation of neutrophils.

Scorpion venom-induced neutrophilia is inhibited by a PAF receptor antagonist in the rat

A dramatic blood neutrophilia is an important feature of the severe envenoming caused by the Brazilian scorpion Tityus serrulatus and may contribute to the development of lung injury in children. We examined the effects of an intravenous injection of T. serrulatus scorpion venom (TsV) on the total number of leukocytes and neutrophils in the blood of anesthetized rats. Injection of TsV (250 microg/kg) induces a significant leukocytosis 2 and 3 h after its injection, explained by an increase in the number of neutrophils. The release of catecholamines and action on adrenoceptors is responsible for most of the systemic manifestations of TsV. However, pretreatment with the beta-adrenoceptor antagonists metoprolol and propranolol or the alpha1-adrenoceptor antagonist prazosin (0.25 mg/kg) did not prevent TsV-induced neutrophilia. Blood neutrophilia induced by TsV occurred simultaneously with a significant reduction of mature neutrophils in bone marrow. Pretreatment with the platelet-activating factor (PAF) receptor antagonists UK-74505 or WEB-2086 prevented TsV-induced increase in blood neutrophils and reduction in the number of neutrophils in the bone marrow. It is concluded that scorpion venom induces blood neutrophilia in rats, explained by a PAF receptor-dependent mobilization of neutrophils from the bone marrow.