Lesion Size in Relation to Ablation Site During Radiofrequency Ablation

This study was designed to investigate the effect of the convective cooling of the tip of the ablation electrode during temperature controlled radiofrequency ablation. In vivo two different application sites in the left ventricle of anaesthetised pigs were ablated and in vitro ablation was performed during two different flow-velocities in a tissue bath, while electrode contact pressure and position were unchanged. Target temperature was 80 °C. Obtained tip temperature, power consumption and lesion dimensions were measured. In vivo lesion volume, depth and width were found significantly larger for septal applications than apical applications (p<0.01) and more power was used (p<0.001). Obtained tip temperature was significantly lower in the septal applications (p<0.001). In vitro increased convective cooling by induction of flow yielded larger lesion volume, depth and width (p<0.01), and had higher power consumptions (p<0.01). Obtained tip temperature did not differ significantly. For the given chosen target temperature power consumption was positively related to lesion volume (r= 0.66 in vivo and 0.65 in vitro), whereas obtained tip temperature was not (r = - 0.49 in vivo and - 0.61 in vitro). We conclude that during temperature controlled radiofrequency ablation lesion size differs for septal and apical left ventricular applications. Differences in convective cooling might play an important role in this respect. This is supported by our in vitro experiments, where increased convective cooling by induction of a flow around the electrode tip increases lesion dimensions and power consumptions. Furthermore we conclude that for the given target temperature the power consumption is positively correlated with lesion volume (p<0.001), whereas the obtained tip temperature is not.     

Effect on a cariogenic challenge of saliva/plaque exchange via a thin salivary film studied by mathematical modelling

Computer models can be powerful tools for studying complex interacting processes. The computer model of events in dental plaque during a cariogenic challenge described here simulates diffusion and metabolism of substrate, plus coupled diffusion/reaction of fourteen other species, charged and uncharged, including acidic metabolic products and fixed buffers. Its extension to deal with the effects of poor contact with bulk saliva when the plaque is presumed covered by a thin salivary film is here considered. Site-specific mixing rates between film and salivary pool were modelled phenomenologically, using data from the literature. Fast mixing was assumed during an initial carbohydrate intake phase (2 min sugar rinse), followed by site-dependent mixing and logarithmic clearance. The analysis also suggested a possible way of estimating local salivary film thickness. Increasing the halving time for exchange between film and bulk saliva was shown to prolong the pH minimum greatly, and to increase mineral loss. The respective roles of fixed buffers as stores of protons and of mobile buffers (especially bicarbonate) as exporters of protons from the inner plaque were emphasised.     

改变检测波长HPLC法测定小檗属植物根中的生物碱

应用改变检测波长反相高效液相色谱法测定了5种小檗属植物根中的尖刺碱、小檗胺、异汉防已碱、非洲防己胺、药根碱、巴马亭和小檗碱。色谱柱为μ-Bondapakphenyl;流动相为0.02mol·L^-1磷酸二氢钾乙腈(7:3);0.0～10.0min用203nm检测,10.0～30.0min用346nm检测;流速1.0ml·min^-1。根据这7种生物碱的紫外吸收波长的不同在色谱过程改变检测波长,提高了分析的灵敏度和准确度。     

Hemodynamic significance of the paraumbilical vein in portal hypertension: assessment with duplex US

Hemodynamic evaluation of portal and umbilical venous flow with duplex ultrasound (US) was performed in 11 patients with cirrhosis of the liver and a large umbilical vein. Two of these patients had hepatofugal flow in the umbilical vein exceeding hepatopetal flow in the portal vein. These two patients had no evidence of esophageal varices and bleeding. The remaining nine patients had esophageal varices. In these patients, the hepatopetal flow in the portal vein exceeded the hepatofugal flow through the umbilical vein. The authors conclude that duplex US may help identify the massive hepatofugal flow through a large umbilical vein that may reduce the likelihood of esophageal varices and variceal bleeding.     

改良乳房下真皮乳腺单蒂瓣巨乳缩小术

目的为了进一步保证巨乳缩小术后乳头乳晕的血供和感觉，减少手术并发症。方法设计应用乳房下真皮单蒂瓣，并保留部分乳腺组织的垂直乳腺蒂，及切除的乳腺组织位于乳房下方两侧的巨乳缩小术，自１９９４年１月至１９９５年１１月，为６７例（１３２侧）巨乳患者在法国斯德拉斯堡欧洲美容整形诊所进行治疗。结果术后全部患者无乳头乳晕并发症，感觉正常。结论结合乳腺垂直蒂和乳房下真皮单蒂瓣的改良巨乳缩小术，不但可以确保乳头乳晕的血供，且可减少感觉损伤，降低手术并发症，及提供良好形态。