Population toxicokinetics of tetrachloroethylene

 In assessing the distribution and metabolism of toxic compounds in the body, measurements are not always feasible for ethical or technical reasons. Computer modeling offers a reasonable alternative, but the variability and complexity of biological systems pose unique challenges in model building and adjustment. Recent tools from population pharmacokinetics, Bayesian statistical inference, and physiological modeling can be brought together to solve these problems. As an example, we modeled the distribution and metabolism of tetrachloroethylene (PERC) in humans. We derive statistical distributions for the parameters of a physiological model of PERC, on the basis of data from Monster et al. (1979). The model adequately fits both prior physiological information and experimental data. An estimate of the relationship between PERC exposure and fraction metabolized is obtained. Our median population estimate for the fraction of inhaled tetrachloroethylene that is metabolized, at exposure levels exceeding current occupational standards, is 1.5% [95% confidence interval (0.52%, 4.1%)]. At levels approaching ambient inhalation exposure (0.001 ppm), the median estimate of the fraction metabolized is much higher, at 36% [95% confidence interval (15%, 58%)]. This disproportionality should be taken into account when deriving safe exposure limits for tetrachloroethylene and deserves to be verified by further experiments. Received: 20 April 1995/Accepted: 24 August 1995     

白细胞介素—2新的功能位点及其中枢镇痛作用

白细胞介素－２（ＩＬ－２）不仅是重要的免疫调节因子，而且还具有重要的中枢调节作用。本实验以钾离子透入引起大鼠甩尾反应为指标，发现侧脑室注射ＩＬ—２能显著提高动物痛阈，并能被纳洛酮所阻断，表示ＩＬ－２的中枢镇痛作用可能与阿片受体有关。利用基因定位突变技术获得的无免疫活性ＩＬ－２实查体仍具有中枢镇痛作用，表明ＩＬ—２分子上发挥镇痛和免疫调节作用的功能位点是相互独立的。纳洛酮能够阻断ＩＬ—２的中枢镇痛作用，而不能影响ＩＬ—２增殖ＣＴＬＬ－２细胞的作用，提示ＩＬ－２发挥镇痛和免疫调节作用可能通过不同的受体途径。ＩＬ－２分子中第４５位Ｔｙｒ残基突变为Ｖａｌ后，虽仍保留了免疫活性，但丧失了镇痛功能，表示４５位Ｔｙｒ残基是ＩＬ—２发挥中枢镇痛功能的关键残基之一。我们推测ＩＬ—２的镇痛功能位点可能在ＩＬ—２分子中第４５位Ｔｙｒ残基附近区域。     

精氨酸加压素（AVP）的衍生物AVP4—8不能作用于AVPV1a受体而诱发电流反应

在微量注射大量肝脏ｍＲＮＡ之后，通过电压箝方法进行功能鉴定，两栖类卵母细胞成功地表达了ＡＶＰＶ１ａ受体。但在灌流ＡＶ４－８溶液时，却不能诱导卵母细胞产生内向振荡电流反应。提示ＡＶＰ４－８不能通过ＡＶＰＶ１ａ受体而介导生理学效应。     

Effect of autocontrol micromotion intramedullary interlocking nail on fracture healing： an experimental study

Objective: To investigate the effect of autocontrol micromotion locking nail ( AMLN ) on experimental fracture healing and its mechanism. Methods: 16 goats undergoing both sides of transverse osteotomy of the femoral shafts were fixed intramedullary with AMLN and Gross-Kempf (GK) nail, respectively. The follow-up time was 7, 14, 28 and 56 days. Roentgenographic, biomechanical, histological, scanning electromicroscopic and biochemical analyses were done. Results: (1) The strength of anticompression, antiflexion and antitorsion in the fractural end in the AMLN-fixed group was higher than that of GK nail-fixed group; whereas, the rate of stress shelter in the fractured end decreased significantly (P<0.01). (2) The content of the total collagen, insoluble collagen, calcium and phosphate in the AMLN-fixed group was higher than that in the GK nail-fixed group (P<0.05). (3) Histological observation and quantitative analysis of calluses revealed that AMLN could promote the growth of bridge calluses and periosteum calluses. Hence the facture healing and remolding process achieved early, which was much better than traditional GK nail fixation. (P<0.05). (4) 7-14 days postoperation, the calluses of AMLN-fixed group was flourish and camellarly arranged and the collagen fibril formed constantly in the absorption lacuna of bone trabecula. 28-56 days postoperation, the collagen fibril was flourish around the absorption lacuna and was parallel to the bone's longitudinal axis. Active bony absorption and formation were seen, so was remolding and rebuilding. Haversian system was intact and the bony structural net was very tenacious because of the deposition of calcium salt. None of the above findings was observed in the GK nailfixed group. Conclusions: The design of AMLN accords well with the plastic fixation theory. As the geometry ametabolic system constituted by the intramedullary fixation instruments and the proximal and distal end of the fracture is very firm and stable, the disturbance to the physical stress distributed in the fractural end is light. The generation and conduct of the intermittent physical stress between the fractural parts could reach the balance between stress conduct and stress protection. The feature that the healing and remolding take place at the same time speeds up the fractural healing process.     

Effect of Ureaplasma urealyticum infection on IL-laand IL-6 secretion by rat Sertoli cells

Objective: To observe the effect of Ureaplasma urealyticum (UU) infection on the IL-1α and IL-6 secretion by rat Sertoli cells. Methods: Eight 20-day-old UU-free male SD rats (average weight 40 g) were used. Under sterile condition, the testes were removed and separately digested with collagenase typeⅡand hyaluronidase. High purity Sertoli cells were then isolated and adjusted to a concentration of 8×105/mL with DMEM/Ham's F-12. In the infected group, 1 mL Sertoli cell suspension and 100 mL UU (serotype 8, T960) were introduced into one well of a 24 well culture plate. In the control group, 1 mL Sertoli cell suspension and 100 mL medium were introduced. IL-1αand IL-6 were determined in the culture supernatant with ELISA. Results: The production of IL-1αwas significantly lower and of IL-6 significantly higher in the infected than those in the control groups (P<0.01). Conclusion: UU infection reduces the IL-1αand increases the IL-6 secretion by rat Sertoli cells. UU infection is probably involved in     

AGFA LR5200激光相机的保养与维护

阐述了AGFALR5200激光相机的工作原理、日常使用保养。     

社区卫生服务信息系统功能建模研究

理顺功能关系、理清业务流程是构建社区卫生服务信息系统的前提和基础,功能建模是理顺功能关系的一个重要手段。在研究现有的各种功能分析方法的基础上,本文以IDEF0模型方法为基础,提出了社区卫生服务信息系统功能建模方法。通过建立功能、数据和约束之间的内在联系,为系统的功能设计和数据分析提供了基础。     

硬膜外阻滞对高血压患者血压的影响

目的:比较未经正规治疗的高血压患者中位和低位硬膜外阻滞时对血压的影响。方法:有明确的高血压病史的急诊中上腹部手术麻醉病例42例(Ⅰ组)和下腹部手术麻醉病例47例(Ⅱ组),采用硬膜外阻滞后,比较手术时间、局麻药总量、麻醉后动脉血压下降的幅度和时相。结果:(Ⅰ组)手术历时62.3±17.8min,局麻药总量为利多卡因387.0±31.2mg,(Ⅱ组)手术历时56.8±14.9min,利多卡因总量366.7±30.1mg,均无显著差异。Ⅰ组硬膜外麻醉前平均动脉压为123.6±13.2mmHg,麻醉后最低的平均动脉压为69.5±10.0mmHg,出现最低平均动脉压的中位时间为26.3min,Ⅱ组麻醉前的平均动脉压为117.3±15.7mmHg,麻醉后最低平均动脉压为71.0±7.4mmHg,出现最低平均动脉压的中位时间为21.3min。两组在硬膜外阻滞后平均动脉压下降幅度及下降时间方面无显著差异。结论:未经很好控制的高血压患者硬膜外阻滞后均可引起血压急骤下降,低位硬膜外阻滞与中高位阻滞引起的血压下降幅度和时相相似。