Fat and water separation in balanced steady-state free precession using the Dixon method.

In this work the feasibility of separating fat and water signals using the balanced steady-state free precession (SSFP) technique is demonstrated. The technique is based on the observation (Scheffler and Hennig, Magnetic Resonance in Medicine 2003;49:395-397) that at the nominal values of TE = TR/2 in SSFP imaging, phase coherence can be achieved at essentially only two orientations (0 degrees and 180 degrees ) relative to the RF pulses in the rotating frame, under the assumption of TR < T2, and independently of the SSFP angle. This property allows in-phase and out-of-phase SSFP images to be obtained by proper choices of the center frequency offset, and thus allows the Dixon subtraction method to be utilized for effective fat-water separation. The TR and frequency offset for optimal fat-water separation are derived from theories. Experimental results from healthy subjects, using a 3.0 Tesla system, show that nearly complete fat suppression can be accomplished.     

Working‐correlation‐structure identification in generalized estimating equations

Selecting an appropriate working correlation structure is pertinent to clustered data analysis using generalized estimating equations (GEE) because an inappropriate choice will lead to inefficient parameter estimation. We investigate the well‐known criterion of QIC for selecting a working correlation structure, and have found that performance of the QIC is deteriorated by a term that is theoretically independent of the correlation structures but has to be estimated with an error. This leads us to propose a correlation information criterion (CIC) that substantially improves the QIC performance. Extensive simulation studies indicate that the CIC has remarkable improvement in selecting the correct correlation structures. We also illustrate our findings using a data set from the Madras Longitudinal Schizophrenia Study. Copyright © 2008 John Wiley & Sons, Ltd.     

桡骨远端关节内骨折外固定器治疗的相关机制和原则探讨

目的 分析和探讨桡骨远端关节内骨折外固定器治疗的相关机制和原则.方法 笔者采用Orthofix外固定器和国产组合式外固定器治疗桡骨远端关节内骨折45例46肢,以齐藤英彦法对资料完整的37例38肢病例进行分型,分析其影像学表现、损伤和治疗相关机制以及特点.结果 各型复位方向和外固定腕关节位置均与致伤暴力方向相反.骨折愈合时间平均为43 d(37～62 d),平均随访时间14个月(3～56个月),按Dienst标准评估腕关节功能及疗效:优21例22肢,良10例10肢,可6例6肢.结论 闭合复位外固定能很好地解决桡骨远端关节内骨折的治疗问题,特别适用于粉碎型关节内骨折.其治疗原则是复位方向及腕关节外固定位置与损伤机制、移位情形相反,个别骨折块辅以切开复位时须强调有限切开,必须重视部分病例伴有的同侧桡骨中远段骨折和同侧尺骨远段骨折的处理.     

Trans fat intake lowers total cholesterol and high-density lipoprotein cholesterol levels without changing insulin sensitivity index in Wistar rats

Epidemiologic studies have demonstrated that trans fat intake increases the risk of some chronic diseases. We hypothesize that trans fat intake would increase the risk of cardiovascular disease and type 2 diabetes mellitus by changing the lipid profile in plasma, the secretion of adipokines in adipose tissue, and the insulin sensitivity. Accordingly, the major objective of present study was to investigate the effect of dietary intake of trans fat on lipid profile, insulin sensitivity, and adipokine levels in plasma. Two groups of Wistar rats were fed a diet containing 4.5% trans fat or a control diet containing no trans fat for 16 weeks. Fasting glucose level was monitored every 2 weeks. At the end of feeding experiment, blood, heart, kidney, liver, omental adipose tissue, and semitendinosus muscle were collected. The trans fat content in organs, lipid profile, adipokine, insulin, and glucose levels in plasma were analyzed. The trans fat content in adipose tissue, heart, kidney, liver, and muscle of rats fed trans fat were 169.9, 0.6, 1.2, 1.7, and 2.5 mg/g samples, respectively. The trans fat content in these organs contributed to 15.9%, 1.2%, 2.3%, 4.3%, and 6.1% of the total fat, respectively. The plasma glucose level, insulin level, and insulin sensitivity index were not significantly different between the trans fat and control groups. The results indicated that trans fat intake might not be related to insulin resistance. However, lipid profile and plasma adipokine levels were significantly changed after trans fat feeding. The trans fat fed group showed significantly lower total cholesterol and high-density lipoprotein cholesterol levels than the control group. The decreased high-density lipoprotein cholesterol level may indicate the detrimental effect of trans fat intake on lipid profile. Adiponectin and resistin levels were significantly higher in the trans fat group than the control group. Leptin levels were significantly lower in the trans fat group than the control group. The results indicated that dietary intake of trans fat can significantly change the adipokine levels, but the possible links between adipokine level change caused by trans fat intake and metabolic effects of this change need further investigations.     

王成荣治疗子宫内膜异位症“火热致瘀”理论探讨

王成荣研究员长于以中医药诊治子宫内膜异位症（EMT），根据其临床经验认为“火热致瘀”是EMT的基本病因、病机，且火热与瘀血互为因果、恶性循环，致使EMT病程缠绵不愈、反复复发。王老据此提出“清热解毒、化瘀散结”的治疗法则，为治疗EMT开辟了另一思路和理论。     

荧光示踪法研究逆行岛状皮瓣静脉回流

目的探讨采用荧光示踪法研究逆行岛状皮瓣静脉回流的可行性，并初步观察静脉回流规律。方法20只新西兰大白兔，每只取耳静脉血0．ImL，分离RBC并用FITC标记。流式细胞仪检测已标记的RBC阳性率及荧光强度，倒置荧光显微镜观察其形态。取20只新西兰大白兔，在动物双侧后肢内侧分别建立4cm&#215;3cm隐动、静脉逆行岛状皮瓣模型（n=10）和顺行岛状皮瓣模型（n=10），血管蒂长3cm。将一侧后肢随机设定为实验组，皮瓣制备后注射已标记的RBC悬液5pL；对侧为对照组，不注射示踪剂。实验组按顺行和逆行皮瓣分成两组，即顺行皮瓣组和逆行皮瓣组，每组10个；再根据注入示踪剂途径不同，分为动脉和静脉2个亚组，每亚组5个皮瓣。注射示踪剂5S后取下皮瓣立即冷冻，取连续的3张冰冻切片（5～7pm），其中2张行HE染色和GENMED染色，另]张不染色直接压片，荧光显微镜观察荧光分布。结果流式细胞仪分析FITC标记的RBC阳性率在99％以上，荧光强度均≥10。；倒置荧光显微镜下标记的RBC呈均匀分布的绿色荧光，荧光强度均匀、稳定。冰冻切片显示实验组皮瓣蒂部均出现荧光，对照组未见荧光。顺行岛状皮瓣组荧光主要分布在静脉腔、静脉壁、动脉内膜和外膜；逆行岛状皮瓣组荧光分布在动脉内膜、外膜和静脉壁。结论荧光示踪剂可用于静脉回流研究，顺行岛状皮瓣静脉主要通过静脉腔、静脉壁、动脉内膜和外膜回流；逆行岛状皮瓣静脉主要通过动脉内膜、外膜和静脉壁的“迷宫式途径”回流。     

In vivo determination of body fat by measuring total body carbon

Total body carbon (TBC) is measured in vivo by neutron inelastic scattering. The fast neutrons needed for the irradiation are produced by a miniature deuterium-tritium (D-T) neutron generator. Body fat and protein are the main contributors to TBC. Bone ash and carbohydrates contribute less than 3%. Fat is calculated from TBC after the subtraction of the carbon contributions from protein, bone, and glycogen. The technique was applied to 14 normal volunteers (8 females, 6 males) aged 24-94 y who underwent neutron inelastic scattering and neutron activation measurements for body carbon, nitrogen, and calcium. The initial results agree with other techniques. Unlike models that evaluate body fat by subtracting lean body mass from body weight, the TBC technique is not sensitive to assumptions on the composition of lean body; therefore, it is appropriate for studies of adults of any age and health condition.