Hepatic Disposition Characteristics of Electrically Charged Macromolecules in Rat in Vivo and in the Perfused Liver

The effect of electric charge on the hepatic disposition of macromolecules was studied in the rat. Charged derivatives of dextran (T-70) and bovine serum albumin (BSA), mitomycin C–dextran conjugates (MMC-D), and lactosaminated BSA (Lac-BSA) were employed as model macromolecules. After intravenous injection, cationic macromolecules were rapidly eliminated from plasma because of their extensive hepatic uptake, while anionic and neutral macromolecules were slowly eliminated. Cationic macromolecules were recovered from parenchymal and nonparenchymal hepatic cells at a cellular uptake (per unit cell number) ratio of 1.4–3.2, while that of Lac-BSA was 14. During liver perfusion using a single-pass constant infusion mode, cationic macromolecules were continuously extracted by the liver, with extraction ratios at steady-state (E _ss) ranging between 0.03 and 0.54, whereas anionic and neutral macromolecules were almost completely recovered in the outflow at steady state. The E _ss for cationized BSA (Cat-BSA) and cationic MMC-Dcat were concentration dependent and decreased at low temperatures and in the presence of colchicine and cytochalasin B. The possible participation of the internalization process in the uptake of cationic macromolecules by hepatocytes was suggested.     

头皮电烧伤骨外露带毛发皮瓣修复

目的：探讨头皮电烧伤骨外露用头皮扩张皮瓣移植修复的临床效果。方法：采用早期扩创,保留部分坏死骨质,用邻近头皮扩张使带毛发的头皮面积扩大后移植覆盖创面,电性失活骨质在血循环良好的皮瓣覆盖下,为周边及基底健康骨质生长起到支架作用,皮瓣扩张到一定面积后移植到裸露骨质上,使其得以修复。结果：在治疗的9例中,除1例皮瓣边缘在1．5cm×1．5cm坏死外,其余皮瓣全部成活,未发生感染坏死,创面均一次性封闭。结论：头皮电烧伤骨外露扩张后皮瓣带毛发修复,可缩短创面愈合时间,外形较好,易掌握,效果较为满意。     

高压脉冲电场对乳铁蛋白抑菌性能的影响

研究了高压脉冲电场(PEF)对乳铁蛋白(LF)的抑菌性能的影响。结果表明,LF质量浓度、电场强度、脉冲频率、脉冲数的增加,有利于LF抑菌能力的增强,而温度的升高会使之减弱。电场强度为35 kV/cm时,LF的抑菌能力达到最大值。LF的质量浓度越高,对电场强度的变化越敏感。当脉冲个数达到744时,LF的相对抑菌能力提高了34%。处理温度为15～55℃时,PEF处理的LF的相对抑菌性能增长了5%左右。当温度升高至65℃时,LF的相对抑菌能力下降显著,降低了约22%。     

Nucleus24型人工耳蜗植入后的电极有效性

目的：随访耳蜗植入后出现蜗外电极或坏损电极的情况，评价人工耳蜗植入后电极的有效性。方法：1998年6月至2002年8月53例Nucleus CI24M型耳蜗植入者，在术中及术后映射调图时进行电极阻抗测试，确定有无电极坏损及其坏损时间。开机时拍摄耳蜗位X线平片，确定电极是否完全植入。分析手术过程和术者经验对电极有效性的影响。结果：电极出现坏损的比例为13．2％，电极在术中插拔两次以上而造成电极坏损的危险度为0．4656。4年累积生存率达96．2％。不完全植入的比例为15．1％，其中又以耳蜗形态异常者居多(7／11)。结论：Nucleus CI24M型植入体在开机1～4年内的可靠性较高。电极序列在术中插拔两次以上，是导致电极坏损的主要原因。患者耳蜗的纤维化、畸形以及术者经验等因素可能导致电极不完全插入。     

电刺激黑质对脑干伤害性单位放电的影响

本实验采用单细胞外记录神经元单位放电的方法，在Ｗｉｓｔａｒ大鼠上观察到网状巨细胞核。一区伤害性神经元５７个，其中伤害兴奋性神经元（ＮＥＮ）４２个，伤害抑制性神经元（ＮＩＮ）１５个。电刺激黑质对ＮＥＮ（２９）和ＮＩＮ（８的放电呈抑制作用，其反应百分率分别由刺激黑质第１分钟时的１．０±２．１％和－２０．４±６．２％，降到第５分钟时的－８３．６±１２．３％和－６５．４±１０．７％（Ｐ＜０．０１）。刺激黑质对少数ＮＥＮ（１３）和ＮＩＮ（７）的放电有兴奋作用，其值分别由第］分钟时的２０．５±７．３％和１．０±３．４％，升高到第５分钟时的７４．５±１０．７％和２１，５±８．６％（Ｐ＜０．０５）。氟哌啶醇注入ＰＡＧ腹外侧部可阻断刺激黑质的效应，这提示从黑质到网状巨细胞核α－区存在着一条痛调制通路，而且这种通路的递质是多巴胺能的。     

A Critical Period of Ventricular Fibrillation More Susceptible to Defibrillation: Real-Time Waveform Analysis Using a Single ECG Lead

Previous studies have suggested that variations in the underlying ventricular fibrillation (VF) waveform may be one of the factors responsible for the probabilistic nature of defibrillation. The heart appeared to be more susceptible to defibrillation at higher absolute VF voltages (AVFV). This study investigated in an open-chest canine model (n = 8), a newly developed system that analyzed the VF waveform in real-time, instantaneously determined the time to shock, and immediately delivered a fixed low energy DC shock. A two parameter tracking technique using a running long-term and short-term AVFV average was devised to automatically identify a high voltage peak area of the VF waveform, which has been hypothesized to represent a critical period susceptible to defibrillation. Using a DC shock estimated at the 50% success level, the performance using this technique in 58 defibrillation trials was compared to the performance of the conventional method of shocking at a fixed time (random shock method) in 62 trials. Patch size, electrode location, and discharge voltage were kept constant while VF duration, transmyocardial resistance (TMR), energy delivered, and AVFV at the point of shock were measured. Shock energy and current, TMR, and VF duration were similar with both shock methods. A significantly higher AVFV was observed for trials performed with the peak shock method (0.66 ± 0.02 mV) as compared to trials performed with the random shock method (0.25 ± 0.09 mV) (P < 0.003). Using lead II as the only sensing lead, the success rate was increased in 6 of 8 dogs (75%) with the new method. One animal showed identical performance, and one animal a worse performance. The overall increase in success rate was 24% using a single ECG lead (range 0%-100%; P < 0.04). Our data document that using this algorithm a period of high VF voltage can be detected in realtime. The improved success in the majority of animals supports the hypothesis that a critical period susceptible to defibrillation exists during VF. However, the high AVFV detected using a single ECG lead did not translate to an improved success rate in all animals. This suggests that other factors in addition to the VF voltage measured on a single lead of the ECG are important in characterizing this critical period.     

修饰电极技术在维生素K_1含量测定中的应用

日的:寻找一种测定溶液中维生素K,含量的新方法、方法:由修饰玻碳电极为工作电极的三电极体系,用锁相交流溶出伏安法进行测定。结果:峰电流(ip)与维生素K1的浓度(c)在7.21 X 10-7g/ml～8.11×l0-6 g/ml范围内呈现良好的线性关系,检出限为7.8×10-8g/ml。结论:该方法与其它方法相比,简便、快捷,结果令人满意     

A Pilot Study: Defibrillation Thresholds in Dogs are Similar with Isoflurane, Halothane, and Pentobarbital

The objective of this pilot study was to determine if three common anesthetic drugs have differing effects on the measurement of defibrillation thresholds (DFT) in dogs. The drugs compared were pentobarbital, isoflurane, and halothane. We used six dogs, which were surgically instrumented, in a chronic study design. Each dog had two internal defibrillation patches placed on its heart, which were used to deliver the defibrillation energy. DFT was determined while each dog was anesthetized under each of the listed drugs in a crossover design. This pilot study suggests that differences in DFT due to the anesthetic drugs is not significant in studies with low numbers of animals (halothane 14.5 ± 1.0, isoflurane 14.2 ± 1.0, pentobarbital 12.8 ± 1.0;P = NS; mean ± SE). Tbe variation in DFT between individual animals is much larger than the difference in DFT due to the drugs.     

Comparison between laser and electrical ablation of ventricle in dogs: Hemodynamic,pathologic and electrocardiographic observations

Summary To characterize and compare the pathologic, hemodynamic and electrocardiographic changes of both transeatheter laser and electrical energy on ventricle, 33 subendocardial myocardium lesions were induced at energy 60, 120 and 240 Joules by either transcatheter laser irradiation or electrical shock in 7 anesthetized dogs. The following results were observed: 1) Both laser and electrical ablation on myocardium created nonhomogeneous myocardium injury, but laser ablation caused mainly focal tissue vaporization and necrosis, while electrical shock induced widespread tissue degenerations; 2) Both laser and electrical induced-lesion dimensions increased parallel to the total dosage of energy; 3) Laser ablation caused mainly (90%) single ventricular premature beats and 86 % of them occurred within the first minute after energy discharged, while ventricular tachycardias were found in any electrical energy groups; ventricular fibrillations occurring during laser and electrical ablation were 5 % and 13 % respectively (P< 0.01): 4) A decrease in aortic blood pressure and an increase in central verous pressure induced by laser ablation were significantly less than that produced by the same amount of electrical energy (P<0.0l). Our preliminary results have shown that transeatheter laser ablation has great potential for becoming a practical method in the management of refractory tachycardias.     

A clinical comparison of 2 electric toothbrush designs

Abstract A single blind 30 day study compared the reduction of plaque and gingivitis for the Hapika® Powerbrush to the Interplak® ultra 10 tuft. A longitudinal parallel group design was utilized and screening evaluation was performed to determine patient eligibility prior to study enrollment. 66 subjects were entered into the study and assigned to 1 of 2 groups, each using one of the toothbrushes. At baseline, subjects received an oral soft tissue exam, a dental hard tissue exam, and were scored by the Lobene modification of the Löe and Silness gingival index (GI). Plaque was then disclosed and scored both pre and post brushing using the modified Turesky plaque/debris examination and an interproximal bleeding examination was performed post-brushing. On days 15 and 30, after an oral soft tissue and GI examination, plaque was graded by the Modified Turesky plaque/debris exam. Subjects then brushed and were graded by the Modified Turesky plaque/debris examination and an interproximal bleeding index examination. The results showed that both brushes provided a similar change in clinical indices. All produced a statistically significant reduction from baseline to day 30 for the gingival index (26.5-29.1%), the bleeding index (13.8-24.1%), and the plaque index (16.9-19.4%), A comparison of pre and post brushing scores for the plaque index at 30 showed that both brushes reduced plaque similarly with a statistically significant reduction (P<0.05) from their pre-brushing plaque index scores at all time periods.