New ways of performing in vivo flow velocity measurements in the basilar artery

The basilar artery is the only large artery in which two flows merge, and this is reflected in the flow downstream. We report quantitative flow — velocity measurements with a phase-based MR technique, i.e. the Fourier velocity encoding method, in the basilar artery of a volunteer. To our knowledge, this has not previously been performed successfully. A comparison is made with the results of flow velocity measurements in the basilar artery with transcranial Doppler ultrasonography; the techniques agreed very well. Although Doppler ultrasonography is still most widely used, no information on the flow rate and the flow velocity distribution in the basilar artery can be provided. MR flow measurement techniques appear promising when detailed information on the flow velocity distribution and flow rate is needed.     

Eight years'' experience with a structured clinical examination

A structured clinical examination has been an integral component of the final-year examinations conducted by the Departments of Medicine and Surgery at the University of Adelaide for the last 8 years. It has been used as an alternative to the traditional clinical examination. This paper describes the results of ongoing student and examiner surveys carried out to determine their views and satisfaction with this new approach. It also briefly discusses the feasibility of introducing such an examination into a conventional medical school environment. The surveys showed a remarkable level of acceptance and support by both students and examiners. This positive reaction has been maintained over the 8-year period. The main reasons seem to be its perceived relevance and fairness. Students also appear to be directing their learning in a direction thought desirable by teachers. No significant problems have been encountered with the practical implementation of the method.     

肥胖对儿童骨骼发育的影响

对89名单纯性肥胖儿童做了手腕部骨龄发育的病例对照研究。结果表明:(1)肥胖儿童骨龄提前(平均男孩提前1.02岁,女孩提前0.74岁,P<0.001)。(2)肥胖儿童骨骼发育速度比正常儿童快(平均男孩快0.117y/a,女孩快0.09y/a,P<0.001)。(3)男孩肥胖度与骨龄增值之间以及骨龄与身高之间均存在有同向变化关系。     

Can past academic criteria predict students at risk of future failure?

A significant minority of medical and dental students fail their undergraduate courses. Early warning systems (EWSs) have been developed in some areas of higher education to predict 'at-risk' students at an early remedial stage. An attempt is made to develop an EWS to predict failure in the bacteriology component of the Batchelor of Dental Surgery course at Manchester Dental School. A system based on class tests and previous end-of-year performance is derived which is used to predict those students likely to fail or fall in the bottom 20-25% in their finals examination. The predictors are combined by a simple equal weights method, which is found to have the same predictive power as using multiple regression. Failure was correctly predicted in 60% of cases, at the expense of 71% false alarms. The high number of false alarms reflects the low failure rate rather than the lack of predictive information. The need for effective cross-validation of EWSs is discussed; many previous studies have not been tested on independent data.     

2-甲基-7-亚甲基-1,4,6-三氧螺[4,4]壬烷与丙烯腈、丙烯酸甲酯的共聚合反应及竞聚率的测定

用高效液相色谱跟踪2-甲基-7-亚甲基-1,4,6-三氧螺[4,4]壬烷(MMTN)与丙烯腈(AN),丙烯酸甲酯(MA)的共聚合反应。根据Lowry-Meyer共聚积分方程式,采用插值法进行数据拟合测定单体的竞聚率。对于体系MMTN(M_1)-AN(M_2),r_1=0.048;r_2=0.213;MMTN(M_1)-MA(M_2)r_1=0.025,r_2=0.764。说明两组共聚体系均有较强的交替共聚趋势。     

错畸形患者的Howes值测量分析

目的:本研究采用Howes法评估牙弓骨量与牙量的协调性,探讨其在正畸临床诊断与矫治设计确定拔牙与非拔牙中的应用价值。方法:选取第四军医大学口腔医学院正畸门诊患者80人,男、女拔牙与非拔牙各20例。测量牙量(TM)、双尖牙弓宽径(PMD)、双尖牙根尖基骨宽径(PMBAW)、基骨弓长度(BAL),并计算PMD/TM、PMBAW/TM、BAL/TM值,对其进行统计学处理与分析。结果:男女两组比较TM、PMD、PMBAW、BAL值有显著性差异,男性大于女性;但PMD/TM、PMBAW/TM、BAL/TM值无统计学意义;拔牙组与非拔牙组比较,PMD/TM、PMBAW/TM、BAL/TM值有显著性差异。结论:采用Howes法评估牙弓骨量与牙量对正畸临床的诊断和拔牙与非拔牙矫治设计有一定的指导意义。     

超声心动图定量犬冬眠心肌的方法学研究

目的:建立经胸小剂量多巴酚丁胺超声心动图激发试验(Dobu-UCG)评价犬冬眠心肌定量的方法学。材料和方法:成功建立冬眠心肌犬7条3～6个月后进行DoBu-UCG试验,测量Dobu-UCG后的心肌梗死区运动幅度(wall motion amplitude of area with myocardium infarction,MMI)和非梗死区心内膜运动幅度(wall mo-tion amplititude of areas with non myocardium infarction,MNMI)的比值(MMI/MNMI),以及试验后MMI/MNMI与试验前MMI/MNMI的差值(D值);并与实验后测量组织切片的冬眠心肌面积(the area oftotal alive myocardium,ATAM)和梗死区总面积(the area of total infarction myocardium,ATIM)的比值(ATAM/ATIM)进行比较。结果:Dobu-UCG激发试验后MMI/MNMI比值、D值分别与ATAM/ATIM进行对比分析,显示两者均高度相关(r=0.83～0.90,P分别为<0.05和<0.001)。结论:测量Dobu-UCG激发试验后MMI/MNMI比值,以及试验后、前MMI/MNMI差值(D)是定量梗死区内冬眠心肌的较好方法。     

Muscle cross-section measurement by magnetic resonance imaging

Summary Muscle cross-section areas were measured by magnetic resonance imaging (MRI) in the thigh of a human cadaver,. the results being compared with those obtained by photography of corresponding anatomic macroslices. A close correlation was found between MRI and photographic evaluation, differences between the methods ranging from nil to 9.5%, depending on the scan position and the muscle groups. In vivo MRI measurements were performed on 12 female and 16 male students, the objectivity, the test-retest reliability and the variability of the MRI measurements being studied by fixing the scan position either manually or by coronary scan. The latter method appeared to be more objective and reliable. The coefficients of variation for muscle cross-section areas measured by MRI were in the range of those for the planimetry of given cross-section areas. Allowing for differentiation between several small muscle bundles in a given area, MRI proved to be a suitable method to quantify muscle cross-sections for intra- and interindividual analysis of muscle size.     

动脉顺应性及其影响因素

动脉顺应性又称动脉弹性，反映血管内皮功能。已成为预测心血管疾病的重要危险因素。无创测量动脉弹性的方法在临床上已有一定程度的应用。各种方法具有其各自适用范围及局限性。多种干预手段可以影响动脉弹性。合理测量及维持正常的动脉弹性可延缓多种心血管疾病的发生及发展。