Prevalence of vibration-induced white finger and assessment of vibration exposure among travertine workers in Italy

Summary Among 76 stonedrillers and stonecutters/chippers working in the Rapolano travertine quarries (Tuscany, Italy), 27 subjects (35.5%) were affected with vibration-induced white finger (VWF). The median latent period for VWF was ten years (range 0.1–26 years). A VWF prevalence of 8% was found among 60 comparable controls (P < 0.0001). Vibration measurements showed that the frequency-weighted accelerations for two rock-drills and two small chipping hammers ranged from 19.7 to 36.4 m/s². Weighted accelerations between 2.4 and 4.1 m/s². were measured on the handles of a vertical grinder and a hand cutter. Vibration data, daily exposure time and total duration of exposure period were used to calculate two indicators of vibration dose such as the four-hour, energy-equivalent, frequency-weighted acceleration (m/s²) and the vibration exposure level (dB). A significant association between the vibration exposure level and the severity of VWF stages was observed among the travertine operators. The dose-effect relationship proposed by ISO 5349 was not suitable for the data of the present study because it overestimates the risk due to hand-transmitted vibration in the travertine workers. Finally, the results of a cold test indicated that the rewarming time of fingertips to room temperature was more prolonged in the operators with VAT than in those without VWF and in the controls.     

Magnetization Transfer and T2 Relaxation Components in Tissue

T₂ relaxation makes an important contribution to tissue contrast in magnetic resonance (MR) imaging. Many tissues are known to exhibit multicomponent T₂ relaxation that suggests some compartmental segregation of mobile protons on a T₂ timescale. Magnetization transfer (MT) is another relaxation mechanism that can be used to produce tissue contrast in MR imaging. The MT process depends strongly on water-macromolecular interactions. To investigate the relationship between multicomponent T₂ relaxation and the MT process, multiecho T₂ measurements have been combined with MT measurements for freshly excised samples of cardiac muscle, striated muscle, and white matter. For muscle, short T₂ components show greater MT than long T₂ components, consistent with the belief that they represent distinct water environments. For white matter, quantitative MT measurements were identical for the two major T₂ components, apparently because of exchange between the T₂ compartments on a timescale characteristic of the MT experiment. Implications for accurate modeling of MT in tissue and the use of MT for MR image contrast are discussed.     

PCR检测角膜内单疱病毒DNA的实验及临床研究

为了探索单疱病毒性角膜炎的发病机制和快速诊断ＨＳＫ。方法应用多聚酶链反应对感染的ＨＳＫ的２０只纯新西兰白兔和６０例ＨＳＫ患者的角膜进行了单疱病毒－１－ＤＮＡ检测。结果急性感染期的５只兔角膜和１２只人角膜均阳性；用稳定期４５ｄ的兔角供体行部分穿透性角膜移植术，术后５０ｄ１０只兔角膜中７只阳性，稳定期６个月－６年的１８只人角膜片，１２只阳性；３０例临床可疑ＨＳＫ角膜刮取物，２６例阳性；５只未感染ＨＳＫ     

光化学脑梗塞动物模型建立的实验观察

利用某些光敏性染料在特定波长光线作用下发生光化学反应的原理，建立家兔局部脑梗塞动物模型。结果显示，模型制作前后全血粘度高切、低切，血浆脂质过氧化物（ＭＤＡ）均明显升高，红细胞变形指数显著降低（Ｐ＜０．０１）。并观察了脑梗塞病灶的大体形态学、细胞学和超微结构变化。结果表明，该模型制作简单，重复性好，病灶的部位、大小和深度容易控制，动物存活时间长，是一种较为理想的脑梗塞动物模型。     

损毁室旁核对迷走神经抑制皮层诱发的下颌运动的影响

损毁家兔单、双侧室旁核，观察迷走神经对皮层诱发的下颌运动抑制性影响的变化，发现损毁单侧室旁核不影响刺激迷走神经中枢端对皮层诱发的下颌运动的抑制作用；损毁双侧室旁核，迷走神经对皮层诱发的下颌运动的抑制作用消失。     

小柴胡汤口服液药效作用的研究

观察了小柴胡汤口服液的主要药理作用。研究表明,小柴胡汤口服液有显著抑制角叉菜胶诱发的大鼠踝关节水肿(p<0.05),保护四氯化碳所致的大鼠急性肝功能损害,有极显著降低血清SGPT及LDH的作用(P<0.01)。对家兔发热反应也有较好的抑制作用。此外,小柴胡汤口服液对小鼠兔疫反应也有一定的增强作用,可促进小鼠碳粒廓清速率,提高血清溶血素水平及增强鸡红细胞所致的迟发性过敏反应。     

脐疗配合耳穴贴压治疗便秘26例

目的 探讨济疗配合耳穴疗法对便秘的疗效。方法 将50例便秘患随机分成两组，治疗组用济部药物贴敷配合耳穴贴压治疗；对照组单纯用于穴贴压治疗，所获数据采用t检验。结果 治疗组有效率96．15％，对照组有效率83．33％，经统计学处理，P＜0．01，有显性差异。结论 济疗联合耳穴贴压治疗便秘疗效较单纯耳穴贴压效果好，且简单方便，无副作用。     

鹿茸生长素对家兔关节软骨细胞代谢的影响

目的 研究鹿茸生长素对关节软骨细胞增殖的影响。方法 采用家兔关节软骨细胞体外培养和加入同位素3H—TdR标记方法，观察其对3H—TdR掺入细胞DNA合成的影响。结果 加入鹿茸生长素组的3H—TdR的掺入值与对照组有明显差异，细胞增殖作用明显。结论 鹿茸生长素能明显刺激关节软骨细胞的增殖。     

Biexponential diffusion tensor analysis of human brain diffusion data.

Several studies have shown that in tissues over an extended range of b-factors, the signal decay deviates significantly from the basic monoexponential model. The true nature of this departure has to date not been identified. For the current study, line scan diffusion images of brain suitable for biexponential diffusion tensor analysis were acquired in normal subjects on a clinical MR system. For each of six noncollinear directions, 32 images with b-factors ranging from 5 to 5000 s/mm2 were collected. Biexponential fits yielded parameter maps for a fast and a slow diffusion component. A subset of the diffusion data, consisting of the images obtained at the conventional range of b-factors between 5 and 972 s/mm2, was used for monoexponential diffusion tensor analysis. Fractional anisotropy (FA) of the fast-diffusion component and the monoexponential fit exhibited no significant difference. FA of the slow-diffusion biexponential component was significantly higher, particularly in areas of lower fiber density. The principal diffusion directions for the two biexponential components and the monoexponential solution were largely the same and in agreement with known fiber tracts. The second and third diffusion eigenvector directions also appeared to be aligned, but they exhibited significant deviations in localized areas.