Thrombosis Is Reduced by Inhibition of COX-1, but Unaffected by Inhibition of COX-2, in an Acute Model of Platelet Activation in the Mouse

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Chronic Cough and Eosinophilic Esophagitis: An Uncommon Association

An increasing number of children, usually with gastrointestinal symptoms, is diagnosed with eosinophilic esophagitis (EE), and a particular subset of these patients complains of airway manifestations. We present the case of a 2-year-old child with chronic dry cough in whom EE was found after a first diagnosis of gastroesophageal reflux disease (GERD) due to pathological 24-hour esophageal pH monitoring. Traditional allergologic tests were negative, while patch tests were diagnostic for cow's milk allergy. We discuss the intriguing relationship between GERD and EE and the use of patch test for the allergologic screening of patients

Non-allergic rhinitis: a case report and review

Rhinitis is characterized by rhinorrhea, sneezing, nasal congestion, nasal itch and/or postnasal drip. Often the first step in arriving at a diagnosis is to exclude or diagnose sensitivity to inhalant allergens. Non-allergic rhinitis (NAR) comprises multiple distinct conditions that may even co-exist with allergic rhinitis (AR). They may differ in their presentation and treatment. As well, the pathogenesis of NAR is not clearly elucidated and likely varied. There are many conditions that can have similar presentations to NAR or AR, including nasal polyps, anatomical/mechanical factors, autoimmune diseases, metabolic conditions, genetic conditions and immunodeficiency. Here we present a case of a rare condition initially diagnosed and treated as typical allergic rhinitis vs. vasomotor rhinitis, but found to be something much more serious. This case illustrates the importance of maintaining an appropriate differential diagnosis for a complaint routinely seen as mundane. The case presentation is followed by a review of the potential causes and pathogenesis of NAR

Staphylococcus aureus Induces Eosinophil Cell Death Mediated by α-hemolysin

Staphylococcus aureus, a major human pathogen, exacerbates allergic disorders, including atopic dermatitis, nasal polyps and asthma, which are characterized by tissue eosinophilia. Eosinophils, via their destructive granule contents, can cause significant tissue damage, resulting in inflammation and further recruitment of inflammatory cells. We hypothesised that the relationship between S. aureus and eosinophils may contribute to disease pathology. We found that supernatants from S. aureus (SH1000 strain) cultures cause rapid and profound eosinophil necrosis, resulting in dramatic cell loss within 2 hours. This is in marked contrast to neutrophil granulocytes where no significant cell death was observed (at equivalent dilutions). Supernatants prepared from a strain deficient in the accessory gene regulator (agr) that produces reduced levels of many important virulence factors, including the abundantly produced α-hemolysin (Hla), failed to induce eosinophil death. The role of Hla in mediating eosinophil death was investigated using both an Hla deficient SH1000-modified strain, which did not induce eosinophil death, and purified Hla, which induced concentration-dependent eosinophil death via both apoptosis and necrosis. We conclude that S. aureus Hla induces aberrant eosinophil cell death in vitro and that this may increase tissue injury in allergic disease

Effects of temperature on α adrenoceptors in limb veins: Role of receptor reserve

In cutaneous veins of the dog, cooling augments the response to sympathetic nerve stimulation and exogenous norepinephrine (NE). The postjunctional α adrenoceptors in this blood vessel belong to both the α1 and α2 subtypes. Cooling augments α2-adrenergic responses (presumably because of an increased receptor affinity), but depresses α1-adrenergic responses (presumably because of a direct inhibitory effect on the contractile process). When agonists of high efficacy such as NE or phenylephrine are used, an α1 adrenoceptor reserve is present that buffers the response from the inhibitory effect of cooling. This allows the potentiating effect of cold on the α2-adrenergic component of the response to catecholamines to predominate, and the contractile response to exogenous NE and sympathetic nerve stimulation is augmented. By contrast, in deep veins of the limb, cold reduces the contractions evoked by α1- and α2-adrenergic activation. This can be explained best by the absence of a receptor reserve for α1-adrenergic agonists of high efficacy, combined with a reduced density of postjunctional α2 adrenoceptors.link_to_subscribed_fulltex

G-proteins and endothelial responses

G-proteins are transducing proteins that couple a large number of membrane-bound receptors to a variety of intracellular effector systems. Pertussis toxin ADP-ribosylates certain G-proteins causing inhibition of their function. In porcine coronary arteries, pertussis toxin inhibited the endothelium-dependent relaxations evoked by alpha-2-adrenergic or serotonergic receptor stimulation, and by aggregating platelets or thrombin. Relaxations to nitric oxide and endothelium-dependent relaxations to bradykinin, adenosine diphosphate or A23187 were unaffected by the toxin. Therefore, certain endothelium-dependent relaxations are mediated by activation of a pertussis toxin-sensitive G-protein in the endothelial cells, most likely G(i)-protein. In porcine coronary arteries with regenerated endothelium (following in vivo denudation), the endothelium-dependent relaxations caused by the pertussis toxin-sensitive stimuli were reduced and were not further affected by pertussis toxin. Relaxations to be other stimuli were not altered by the regeneration process and were still not affected by the toxin. In regenerating endothelial cells there may be a selective impairment of the G-protein-dependent mechanism for releasing EDRF, which may predispose the blood vessel to vasospasm or the initiation of vascular disease.link_to_subscribed_fulltex

Epithelial-dependent attenuation of bronchial smooth muscle tone

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Threshold phenomena and interactions between receptors

Threshold or subthreshold concentrations of serotonin can augment contractile responses of isolated blood vessels to other vasoconstrictor agents. This report presents a theoretical analysis of threshold facilitation and concludes that the amplifying effect of serotonin may result from the removal of a response threshold. Physiological or pathophysiological alterations in the magnitude of this response threshold between different effector systems or in the efficacy of the vasoconstrictor agonist may account for the variability in the amplifying effect of serotonin observed in vivo and in vitro.link_to_subscribed_fulltex

Sympathetic purinergic vasoconstriction and thermosensitivity in a canine cutaneous vein

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