Articles: histamine.
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Experimental dermatology · Dec 2014
Letter Randomized Controlled TrialPolidocanol inhibits cowhage - but not histamine-induced itch in humans.
Polidocanol is a local anaesthetic and antipruritic compound that is used in the treatment of itching skin conditions such as eczema. Its mechanisms of action are largely ill defined. This study has compared the antipruritic efficacy of topical polidocanol in histamine-induced itch and a histamine-independent, cowhage-induced model of pruritus. ⋯ Itch was recorded at 1-min intervals for 30 min on a 100-mm visual analogue scale. Polidocanol significantly reduced the area under the curve for cowhage-induced itch by 58% (P < 0.05), but had no significant effect on histamine-induced itch. This result underlines the importance of histamine-independent itch models in the development of topical antipruritic agents.
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Urticaria is a dermal edema resulting from vascular dilatation and leakage of fluid into the skin in response to molecules released from mast cells. The major mediator responsible for urticaria is histamine. However, the clinical spectrum and pattern of lesions indicate that other molecules, including prostaglandins, leukotrienes, cytokines, and chemokines, produced at different times after mast cell activation contribute to the polymorphism of this symptom and the variable evolution of this disease. ⋯ Finally, under certain circumstances, T-cells can induce activation of mast cells, as well as histamine release (type IV HS). Nonimmunological urticarias result from mast cell activation through membrane receptors involved in innate immunity (e.g., complement, Toll-like, cytokine/chemokine, opioid) or by direct toxicity of xenobiotics (haptens, drugs). In conclusion, urticaria may result from different pathophysiological mechanisms that explain the great heterogeneity of clinical symptoms and the variable responses to treatment.
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Multicenter Study
H2 receptor antagonists and right ventricular morphology: the MESA right ventricle study.
H2 receptor antagonist (H2RA) use is common and may act directly on the heart through myocardial H2 receptors or indirectly through changes in pulmonary vascular resistance. ⋯ H2RA use was associated with lower RV mass and smaller RV end-diastolic volume. Additional study of histamine and H2 receptors in cardiopulmonary diseases affecting the RV may have direct clinical relevance.
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Hemokinin-1 (HK-1) is a new mammalian tachykinin peptide consisting of the amino acid sequence similar to substance P (SP). Although the function of SP, a representative tachykinin peptide, has been well established in the pain system, that of HK-1 has not yet been elucidated. [Leu(11)]-SP had an antagonistic effect on SP-induced scratching behavior, suggesting that [Leu(11)]-HK-1 may also attenuate the induction of scratching behavior by HK-1. Thus, the effects of a pretreatment with [Leu(11)]-HK-1 were evaluated to clarify the function of HK-1. ⋯ To evaluate the involvement of HK-1 and SP in pruritic processing, the effect of [Leu(11)]-HK-1 and [Leu(11)]-SP on the induction of scratching behavior and c-Fos expression by serotonin (5-HT) and histamine was evaluated. The increased induction of scratching behavior and c-Fos expression by 5-HT and histamine was markedly attenuated by pretreatment with both [Leu(11)]-HK-1 and [Leu(11)]-SP, suggesting that HK-1 and SP may be involved in pruritic processing. These results indicate that HK-1 is involved in pruritic processing and [Leu(11)]-HK-1 is a valuable tool for clarifying the mechanisms underlying pruritic processing.
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The diagnosis of acute life-threatening allergic reactions during anesthesia relies on clinical signs, histamine and/or tryptase measurements, and allergic testing. In patients who die after the reaction, skin tests cannot be performed, and the effect of resuscitation manoeuvres on mediator concentrations is unknown. The authors compared plasma histamine and tryptase concentrations in patients with severe allergic reactions during anesthesia with those measured in patients with shock due to other causes. ⋯ Resuscitation manoeuvres by themselves did not modify mediator concentrations. Virtually all life-threatening reactions during anesthesia associated with mediator concentrations exceeding the thresholds were allergic events. These findings have potential forensic interest when a patient dies during anesthesia.