34 research outputs found

    Unilateral Absence of the Pulmonary Veins: An Unusual Diagnosis With Characteristic Imaging Findings

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    BACKGROUND: Congenital unilateral absence of the pulmonary vein (UCAPV) is a rare entity with characteristic clinical and imaging findings. Despite its congenital nature, the radiographic findings and symptoms of UCAPV may not be recognized at birth and patients may present in childhood or early adulthood with findings that may mimic other diagnoses. METHODS: The evolution of imaging findings in UCAPV is presented through two cases, one of which demonstrates the progression of findings over several years. The embryologic basis of this entity is reviewed and the clinical presentation and characteristic imaging findings including radiographs, nuclear scintigraphy, computed tomography, magnetic resonance imaging and cardiac catheterization are demonstrated. RESULTS: Characteristically, normal at birth, radiographs demonstrate the gradual development of a small lung and ipsilateral pulmonary artery over time. In addition to unilateral absence of the pulmonary veins on CT or MRI, a mediastinal soft tissue mass reflecting the development of mediastinal collaterals is a common finding and should be recognized as secondary to the absent ipsilateral pulmonary veins rather than as a primary process causing occlusion of the pulmonary veins. Scintigraphy will show absent perfusion to the affected lung. CONCLUSION: Awareness of the distinctive imaging findings in this unusual condition is critical to avoid misdiagnosis and to prevent the consequences of UCAPV which include pulmonary hypertension and extensive venous collaterals with or without hemoptysis, both of which may prevent definitive repair

    Glycine reduces platelet aggregation

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    It has been demonstrated that a wide variety of white blood cells and macrophages (i.e. Kupffer cells, alveolar and peritoneal macrophages and neutrophils) contain glycine-gated chloride channels. Binding of glycine on the receptor stimulates Cl(−) influx causing membrane hyperpolarization that prevents agonist-induced influx of calcium. Since platelet-aggregation is calcium-dependent, this study was designed to test the hypothesis that glycine would inhibit platelet aggregation. Rats were fed diets rich of glycine for 5 days, while controls received isonitrogenous valine. The bleeding time and ADP- and collagen-induced platelet aggregation were measured. Dietary glycine significantly increased bleeding time about two fold compared to valine-treated controls. Furthermore, the amplitude of platelet aggregation stimulated with ADP or collagen was significantly decreased in whole blood drawn from rats fed 2.5 or 5 % dietary glycine by over 50 %. Addition of glycine in vitro (1–10 mM) also blunted rat platelet aggregation in a dose-dependent manner. Strychnine, a glycine receptor antagonist, abrogated the inhibitory effect of glycine on platelet-aggregation in vitro suggesting the glycine works via a glycine receptor. Glycine also blunted aggregation of human platelets. Further, the glycine receptor was detected in both rat and human platelets by western blotting. Based on these data, it is concluded that glycine prevents aggregation of platelets in a dose-dependent manner via mechanisms involving a glycine receptor
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