Computer simulation of supraventricular tachycardia with the Wolff-Parkinson-White syndrome using three-dimensional heart models

Supraventricular tachycardias with the Wolff-Parkinson-White (WPW) syndrome have been successfully simulated using a newly developed simulation system. The heart model, including atria and ventricles, was constructed of about 50,000 discrete elements (model cells) in three dimensions with 1.5-mm spatial resolution. The model cells covered all of the types of cells in the actual heart, including the normal myocardium, special conduction system and abnormal cells, such as the bundle of Kent (accessory pathway) and ectopic pacemaker (premature beat). Different model cells were specified by their electrophysiologic parameters, such as action potential, refractory period, and conduction velocity. The WPW syndrome was simulated by setting an accessory pathway between the right atrium and ventricle. Based on this model a premature atrial beat was introduced, which initialized the tachycardia. By adjusting the parameters, three types of reciprocal supraventricular tachycardia were simulated with the reentry circuits (1) formed anterogradely by the A-V node and retrogradely by the accessory pathway, (2) formed anterogradely by the accessory pathway and retrogradely by the A-V node, and (3) confined within the A-V node. Time relations for initializing and maintaining the tachycardias were evaluated. The simulated ECGs were in good agreement with the clinical findings.     

Heart rate at onset and termination of paroxysmal atrial fibrillation in apparently healthy subjects

Eighteen paroxysms were documented on Holter electrocardiogram both at the onset and the termination of paroxysmal atrial fibrillation in 14 apparently healthy subjects. There were large inter- and intraindividual variations and no definite trend was observed in the time and duration of paroxysms. Heart rate at the onset of paroxysms was consistently higher than that at sinus rhythm immediately before atrial fibrillation started. There were 2 patterns in the sequence of heart rate during paroxysms. One was an almost constant heart rate during paroxysms, and the other was a trend toward a decrease in heart rate from the onset to the termination of paroxysms. The duration of paroxysms was within 2 hours in the former group and more than 2 hours in the latter group. There was a reverse correlation between heart rate at the termination of paroxysms and their duration.     

Synergistic effect of heat shock protein 90 inhibitor, 17-allylamino-17-demethoxygeldanamycin and X-rays, but not carbon-ion beams, on lethality in human oral squamous cell carcinoma cells

The purpose of this study is to clarify the effect of a heat shock protein 90 inhibitor, 17-allylamino-17-demethoxygeldanamycin (17-AAG), in combination with X-rays or carbon-ion beams on cell killing in human oral squamous cell carcinoma LMF4 cells. Cell survival was measured by colony formation assay. Cell-cycle distribution was analyzed by flow cytometry. Expression of DNA repair-related proteins was investigated by western blotting. The results showed 17-AAG to have synergistic effects on cell lethality with X-rays, but not with carbon-ion beams. The 17-AAG decreased G(2)/M arrest induced by X-rays, but not by carbon-ion beams. Both X-ray and carbon-ion irradiation up-regulated expression of non-homologous end-joining-associated proteins, Ku70 and Ku80, but 17-AAG inhibited only X-ray-induced up-regulation of these proteins. These results show that 17-AAG with X-rays releases G(2)/M phase arrest; cells carrying misrepaired DNA damage then move on to the G(1) phase. We demonstrate, for the first time, that the radiosensitization effect of 17-AAG is not seen with carbon-ion beams because 17-AAG does not affect these changes.     

Clinicopathologic features of encapsulated hepatocellular carcinoma: a study of 26 cases.

The clinicopathologic features of 26 cases of hepatocellular carcinoma (HCC) surrounded by a grossly distinct capsule-like fibrous tissue were studied. The frequency of this type was 10.3% among autopsy cases of HCC. The mean age of the patients was 64.1 years, which was significantly older compared with that of 143 cases of nonencapsulated HCC. Hepatitis-B surface antigen in serum was positive in 18.7% of the cases studied, the positivity rate being lower than that of HCC in general. Histologically, the tumor was relatively well differentiated and the capsule was the product of slow expanding growth. Intravenous tumor invasion was less frequent compared with other types of HCC. Clinically, celiac angiography proves to be a most useful diagnostic method; a thick capsule may be demonstrated as a thin radiolucent rim around the mass. The clinical course from the early stage is protracted and, if detected early, this type of HCC may be removed surgically.     

子宫肌瘤切除术后妊娠与肌瘤复发相关性分析

目的探讨子宫肌瘤切除术后足月妊娠与肌瘤复发的关系。方法对2007年5月-2009年9月于新疆医科大学第一附属医院接受子宫肌瘤切除术且年龄<40岁的患者84例进行随访。结果 84例患者中9例(10.7%)失访,75例患者平均随访(3.0±0.7)a。24例子宫肌瘤复发,复发率为32.0%。无复发生存曲线提示术后无足月妊娠史的患者子宫肌瘤复发率高于术后有足月妊娠史的患者(P=0.02)。有足月妊娠史的患者复发肌瘤最大直径明显大于无足月妊娠史的患者(P=0.001)。多因素分析结果示子宫肌瘤数目是复发的独立危险因素(P=0.003)。结论肌瘤数目是复发的最重要因素,妊娠分娩不增加复发,但是足月妊娠会增加复发肌瘤的直径,可能会使复发患者更倾向于需要接受进一步的治疗。