Scintigraphic assessment of an ophthalmic gelling vehicle in man and rabbit

Studies of the rate of clearance of a gellan gum formulation (Gelrite) radiolabelled by the inclusion of technetium-99m labelled diethylenetriaminepentaacetic acid were carried out in volunteer subjects and in rabbits. Disposition was followed by gamma scintigraphy and compared with 0.5% w/v hydroxyethylcellulose (HEC) solution and isotonic saline administered to the same subjects. Clearance of all solutions was found to follow bi-exponential kinetics with differences in clearance rates between the two species studied. A significant retention of the gellan gum formulation compared to HEC (p = 0.006) or saline (p = 0.009) was noted in man, but not in the rabbit. In this latter species the HEC showed greater retention compared to Gelrite. The species-specific differences in the precorneal residence of the formulations are attributed to the different physiological responses following instillation of solutions into the eye.     

硫酸多糖对体外人脐静脉内皮细胞损伤的保护作用

研究表明,硫酸多糖体外对多聚阳离子和氧自由基损伤的人脐静脉内皮细胞有保护作用。肝素、硫酸软骨素A抗多聚阳离子损伤作用比同浓度低分子肝素和甘糖酯强。肝素、硫酸软骨素A、甘糖酯抗氧自由基损伤作用优于同浓度低分子肝素。结果显示硫酸多糖有保护血管内皮的作用,其作用可能与所带阴离子基团有关。     

New pharmacologic developments in physical urticaria--therapeutic consequences

Recent evidence suggests that mast cell derived mediators other than histamine are likely to be involved in the pathogenesis of physical urticarias. Much of the work has been performed in idiopathic cold contact urticaria where the presence of neutrophil and eosinophil chemotactic factors, and platelet activating factor-like lipid substances have been previously demonstrated. Now, an increase in prostaglandin D2 measured by GC-MS has been demonstrated in venous blood draining the cold challenged area. This appeared a few minutes later than histamine, but then both substances paralleled the onset, development and subsidence of the urticarial reaction. There appeared to be no quantitative relationship between histamine and PGD2 release. A similar rise in histamine and PGD2 occurred on heat challenge of a subject with the rare localized form of heat urticaria. This rise of both substances was considerably reduced after combined treatment with induction of tolerance and oral indomethacin. The concentrations of PGD2 measured suggested that it plays an indirect role.     

Effect of time of dosing relative to a meal on the raft formation of an anti-reflux agent

Gamma scintigraphy was used in twelve healthy volunteers to establish whether the time of dosing of Liquid Gaviscon relative to a meal influenced its therapeutic action. Indium-113m labelled Liquid Gaviscon was administered to fasted subjects, 30 min after a technetium-99m labelled meal or immediately before ingestion of the meal. The time for 50% of the Gaviscon to empty from the stomach was 0.36 +/- 0.13 h, 3.10 +/- 0.31 h and 0.68 +/- 0.04 h (s.e.m.), respectively. The preparation was found to empty rapidly from the fasted stomach and could not be floated on a meal consumed subsequently. For raft formation to occur, Liquid Gaviscon should be taken 30 min after a meal.     

Responses to questions by medical students about family practice

Medical students frequently have questions about the specialty of family practice. Responses to 30 questions commonly asked about family practice are presented with a review of recent literature. These responses may assist medical students and their advisors in considering the choice of family practice as a career.