Identification of dihydropteridine reductase in human platelets

Normal human platelets were shown to contain the enzyme dihydropteridine reductase. The enzyme was not found in a variety of other cells of hematogenous origin. Partial purification and kinetic and physical data indicated that the platelet enzyme is similar to that previously characterized from liver. Dihydropteridine reductase is important for the regeneration of tetrahydrobiopterin, a required cofactor in hydroxylation reactions involved in biogenic amine formation. The presence of the enzyme may indicate that some synthesis de novo of serotonin and/or catecholamines occurs in platelets, as opposed to a purely storage and transport function. In addition, screening for hyperphenylalaninemia due to dihydropteridine reductase deficiency may become feasible by assaying platelets for enzyme activity.     

Chondromalacia patellae: assessment with MR imaging

Magnetic resonance (MR) images of the posterior patellar hyaline articular cartilage were obtained in 23 subjects to determine if MR imaging could accurately demonstrate the patellar cartilage. Arthroscopy was used as the standard of reference. Three subjects were asymptomatic volunteers. In the remaining 20 who had patellofemoral pain, arthroscopy was performed before MR imaging in seven and afterward in 12; one did not undergo arthroscopy. MR imaging showed focal areas of swelling of the patellar cartilage, focal hypointensity, surface irregularity, areas of thinning, and areas of cartilage loss with exposure of subchondral bone. The surgical findings agreed with those from MR images in all seven patients who underwent arthroscopy before MR imaging and in ten of the 12 who underwent surgery afterward. MR imaging is an accurate means of examining the posterior patellar cartilage and should be considered as an alternative to diagnostic arthroscopy when chondromalacia patellae is suspected.     

HPLC柱切换法对炔诺酮α，β－聚（3－羟丙基）－DL－天冬酰胺在兔体内释放炔诺酮的测定

以柱切换ＨＰＬＣ（ＣＳＨＰＬＣ）技术，对炔诺酮α，β－聚（３－羟丙基）－ＤＬ天冬酰胺在家兔体内释放液中炔诺酮的血药浓度进行了测定，以自制ＯＤＳ预柱，水为流动相联机净化、富集样品；以Ｓｈｉｍ－ｐａｃｋＣＬＣ－ＯＤＳ为分析柱，甲醇－水（７：３）为流动相。结果表明ＣＳＨＰＬＣ对炔诺酮血药浓度有良好的选择性，回收率为８２．６％（ｎ＝５），日内和日间精密度（ＲＳＤ）分别小于４％和６％。在血清０．２２～１．１０μｇ／ｍ１范围内炔诺酮色谱峰面积与浓度有较好的线性关系（ｎ＝５，ｒ＝０．９９８）．