基于实时三维超声图像的二尖瓣环重建及运动分析

二尖瓣环的非平面特性对二尖瓣返流的超声诊断和二尖瓣环成形术的合理设计具有重要意义.基于心脏的实时三维超声图像,我们研究了一种对二尖瓣环三维重建及运动分析的方法.首先通过人机交互方式提取出二尖瓣环的特征点,并根据位置关系对特征点排序,然后利用非均匀有理B样条曲线建立二尖瓣环三维形态模型,并编程实现二尖瓣环的动态显示和运动分析.通过对20组病例分析,初步证明此方法所建模型较准确反映患者的二尖瓣环的运动,能满足二尖瓣环三维可视化和分析研究的需要.     

食管分层应力-应变研究

目的　探讨食管壁各层环向应力 应变分布特征。方法　将 8只Wister大鼠的食管标记、测量在体长度后剪下置于去钙离子Krebs液中。剪下标记的中段食管用做充压试验 ,将其在显微镜下分离成内层食管 (粘膜和粘膜下层 )和外层食管 (固有肌层 )。充压时全层和分层食管均被拉长至在体长度 ,以每分钟升高 2cmH2 O速度匀速充压。根据所测图像的几何数据计算全层和分层食管的Kirchhoff应力和Green应变。零应力状态作为计算应力和应变的基本参照状态。结果　 (1 )食管离体后较在体长度缩短 2 4%。 (2 )全层食管和分层食管的环向应力 应变曲线均符合指数方程τ =(τ +β)eα(ε-ε ) -β(判定系数 >0 .96) ,为非线性关系。 (3 )与全层食管相比 ,分层后内层食管应力 应变曲线较陡直 ,且移向左侧 ,差别有统计意义 (P <0 .0 5 ) ,外层食管的曲线移向右侧 ,差别无统计意义 (P >0 .0 5 ) ,内外两层食管的应力 -应变曲线亦有统计差别 (P <0 .0 5 )。结论　食管壁各层环向应力 -应变均符合非线性关系 ,食管内层不如外层易变形     

The Complete Nucleotide Sequence of the PanAsia Strain of Foot-and-Mouth Disease Virus Isolated in Japan

The complete nucleotide sequence of the foot-and-mouth disease virus (FMDV) O/JPN/2000 strain, the PanAsia strain, was determined by cycle sequencing and primer walking. The 5 end of the genome upstream from homopolymeric poly(C) tract (S-fragment) was 367 nucleotides in length, and the remainder of the genome (L-fragment), excepting the poly(A) tail, was 7808 nucleotides. The L-fragment contains a single open reading frame of 6996 nucleotides terminating at a UAA codon 96 bases from the 3 poly(A) sequence. Comparison of sequences shows that the length of the structural and non-structural protein coding regions are identical to those in the O1/Kaufbeuren strain, and no striking differences such as deletion or insertion were observed between them.     

Psychological functioning across stages of treatment for infertility

Psychological functioning was examined for a cross section of 104 couples in different stages of medical investigation for infertility. Couples were separated into three stages based upon the length of time they had been pursuing medical treatment for infertility: year 1, year 2, and year 3 and beyond. Emotional strain was moderately elevated during the first year, returned to more normal levels during the second year, and showed marked increases beyond year 3. Indices of marital adjustment and sexual satisfaction were stable across the first two stages but deteriorated after the third year. These data suggest that the stage of treatment may exert a major influence upon psychological functioning for infertile couples pursuing medical assistance. The results are consistent with a model of psychological strain that reflects an acute stress reaction to the initial diagnosis and treatment overlaid with a chronic strain response to longer-term treatment.Research was aided by a grant-in-aid of research from Sigma Xi, The Scientific Research Society, a research fellowship from the University of South Carolina, and NIMH Institutional Training Grant MH-15930.     

Biomechanical Properties of Esophagus during Systemic Treatment with Epidermal Growth Factor in Rats

The epidermal growth factor (EGF) is a growth factor with effects on many cell types and tissue. Morphometric and passive biomechanical properties were studied in isolated segments of the esophagus in 22 EGF-treated rats and 12 control rats. The rats were divided into groups with EGF treatment for 2, 4, 7, and 14 days (n=6 for each group except n=4 for the 14 days EGF-treatment group) or saline treatment (n=3 for each group). The mechanical test was performed as a distension experiment in vitro where the whole esophagus was stretched to its in situ length and distended with pressures up to 10 cm H₂O using a ramp distension protocol. The pressure and outer diameter were recorded. Circumferential stress (force per area) and strain (deformation) were computed from the diameter and pressure data using the zero-stress state as reference. The zero-stress state was obtained by cutting esophageal rings radially. This caused the rings to open up into a sector. EGF induced pronounced morphometric changes, e.g., the wall thickness, wall cross-sectional area, and inner and outer circumferential lengths significantly increased during the EGF treatment. Histological analysis showed mucosa and submucosa growth during EGF treatment. The opening angle and residual strains increased with the highest value in the 14 days EGF-treated group (P < 0.05). The change in opening angle depended largely on the change in mucosa thickness. Furthermore, the circumferential stiffness of the esophagus reached a maximum after 7 days EGF treatment (P < 0.01). © 2003 Biomedical Engineering Society. PAC2003: 8719Rr, 8717Ee     

Fine mapping of thymus enlargement gene 1 (Ten1) in BUF/Mna rats

Two polymeric autosomal loci, Ten1 and Ten2, regulate thymus enlargement in BUF/Mna (B) rats. Previously, we mapped Ten1 on chromosome (Chr) 1 to a 20 cM region between Myl2 and D1Mgh11, and Ten2 on Chr 13. To further characterize the precise position of Ten1, 34 and 37 microsatellite markers, that have a polymorphism between the B and WYK (W) and between the B and MITE (M) strains, were used for linkage analysis of thymus enlargement in 105 (WBF1 x B) blackcross (BC) and 78 (B x BMF1) BC rats, respectively. Our data showed that the D1Rat168, D1Rat112, D1Rat323, D1Got186, D1Got187 and D1Got188 markers each gave a peak logarithm of odds (LOD) score of 10.68 for linkage to the thymus ratio in (WBF1 x B) BC rats, and that the D1Rat168, D1Rat197, D1Got184, D1Got186 and D1Got188 markers each gave a peak LOD score of 7.82 in (B x BMF1) BC rats. The two LOD score peaks are coincident in the position of the rat genetic map. All of the markers mentioned above are located in the region between Igf2 and D1Mgh11, in which synteny is conserved with human 11q15.5 and the distal end of mouse Chr 7 or with human 11q13 and the proximal end of mouse Chr 19. Genes existing in these regions are discussed as candidate genes for Ten1.     

Predictability of Individual Differences in Activation Processes in a Field Setting Based on Laboratory Measures

The predictability of individual differences in activation processes was investigated in a multi-method laboratory-field study. Male students of physical education (N=58) were examined under various emotionally activating and physically demanding conditions (mental arithmetic, reaction time, free speech, cold pressor test, bicycle ergometer). The assessment included multi-channel recordings of pre-start phases in an athletic stadium and performance on a 1000 m run. Basal heart rate was also recorded during sleep. This multi-situational assessment was repeated after three weeks, three months, and, for most (N=42) subjects, after one year. Significant relationships exist between scores from corresponding conditions of relaxation, anticipation, and performance of physical exercise. However, with the exception of heart rate, correlation coefficients are rather small and seem to be of questionable predictive validity. A generalizability study further supports the general conclusion: To increase the practical relevance in psychophysiological investigations of stress/strain phenomena, such studies should directly assess individual differences in the criterion situations themselves.     

Cardiorespiratory and thermal effects of wearing gas protective clothing

Summary Six healthy men aged 25 to 37 walked on a treadmill at work levels of 21 and 41% of their for 25 to 30 min wearing gas protective clothing (GPC) consisting of an impermeable suit with a self-contained breathing apparatus (total weight 25 kg) or shorts (control tests, CT) in a temperate environment (t _a 24.3°C ± 1.0°C, rh 30–50%). When the GPC was worn at 21 and 41% , the most prominent increases, compared with the CT, were noted in the heart rate ( ± SE, 120 ± 5 vs 76 ± 3 beats min^–1 and 171 ± 5 vs 103 ± 3 beats min^–1), mean skin temperature (36.1 ± 0.2 vs 31.3° C ± 0.1°C and 36.9 ± 0.3 vs 30.9°C ± 0.4°C) and sweat rate (473 ± 51 vs 70 ± 23 g m^–2 h^–1 and 766 ± 81 vs 135 ± 18 g m^–2 h^–1) indicating a high cardiovascular and thermoregulatory strain, which was not decreased by ventilating the suit with an air flow of 281 min^–1 at 41% . The ventilation, oxygen consumption and production of carbon dioxide increased in relation to the extra weight of the GPC, partly dependent on the dynamic work level. It was concluded that the increase in the physiological load caused by the GPC was so high that the work-rest regimens, workers' level of physical fitness, cardiovascular health and heat tolerance should be considered whenever gas protective clothing is used.     

HIV-1 CRF55_01B毒株流行特征的研究进展

CRF55_01B是我国报道的HIV-1主要流行毒株之一,具有较为独特的流行病学和基因进化特征。近几年HIV-1分子流行病学监测发现CRF55_01B已经成为我国第五个主要流行HIV-1毒株。本研究从他的发现起源、流行情况、致病性和耐药性及参与的重组等方面进行综述,并讨论了与其流行密切相关的社会和生物学因素。     

蠕变局部损伤开裂的有限元模型

建立了蠕变局部损伤法模型,并给出单元进入损伤态的判据和失效的临界拉伸应变条件,局部蠕变损伤理论的实质就是试样是多种不同蠕变性能材料的统一,并由蠕变应力再分布得到证实,应用有限元对双缺口圆试样作了蠕变局部损伤分析,启裂时间和断裂蠕变应变值均与实验结果相吻合。