K562 human erythroleukemia cells demonstrate commitment

Commitment, ie, the decision to express a differentiated phenotype and to terminate proliferation irreversibly in the absence of inducer, was investigated in K562 human erythroleukemia cells. Cells were cultured for 0, 1, 2, 3, or 4 days with inducer and then plated in medium containing methylcellulose without inducer. Daily after plating, hemoglobin content was scored by benzidine staining, and growth was assessed by estimating the cell number per colony. With all inducers used, three types of colonies were found, those containing only benzidine-positive cells, those containing only benzidine-negative cells, and those containing both cell types (mixed colonies). Thymidine produced a progressive increase in the percentage of positive and mixed colonies and a progressive fall in the percentage of negative colonies. Whereas negative colonies grew at an exponential rate with a generation time of about 20 hours, positive colonies reached an average maximum size of 16 cells, representing a total of four divisions. Butyrate had a similar effect, except that the rise was greater for mixed colonies than for positive colonies, and the plateau in positive colony size was less evident. In contrast, CO2 depletion or hemin treatment induced an increase in the fraction of cells staining benzidine positive that was lost rapidly upon removal of the inducing condition. Thus, of the four conditions, thymidine and butyrate caused commitment, whereas hemin and CO2 depletion did not. Thus K562 cells, like Friend cells, demonstrate commitment, but, unlike Friend cells, demonstrate a significant rate of commitment in the absence of inducer and hence form a significant percentage of mixed colonies with or without inducer.     

肺泡膜弥散和肺毛细血管血量特征在不同级别慢性阻塞性肺病患者的表现

目的:了解不同级别慢性阻塞性肺病患者肺泡毛细血管膜弥散量和肺泡毛细血管血量的特点。方法:收集2006-07/2007-03就诊于四川大学华西医院呼吸科的慢性阻塞性肺病患者154例,依据慢性阻塞性肺病方案分级,0级64例,Ⅰ级38例,Ⅱ级26例,Ⅲ和Ⅳ级共26例。行肺通气功能、肺容量、一氧化碳弥散量、肺泡毛细血管膜弥散量和肺泡毛细血管血量测定。结果:154例患者均进入结果分析。①0级与I级慢性阻塞性肺病患者,无论一氧化碳弥散量、肺泡毛细血管膜弥散量和肺泡毛细血管血量都正常。随着慢性阻塞性肺病程度加重,一氧化碳弥散量、肺泡毛细血管膜弥散量和肺泡毛细血管血量均有不同程度降低。Ⅱ级慢性阻塞性肺病时一氧化碳弥散量和肺泡毛细血管膜弥散量下降明显,肺泡毛细血管血量改变不明显。其中肺泡毛细血管膜弥散量出现异常明显早于一氧化碳弥散量和肺泡毛细血管血量,而且较严重。Ⅲ和Ⅳ级慢性阻塞性肺病的肺泡毛细血管血量下降明显。②一氧化碳弥散量、肺泡毛细血管膜弥散量和肺泡毛细血管血量与慢性阻塞性肺病级别、残气量/肺总量成负相关,与第1秒用力呼气容积/用力肺活量和第1秒用力呼气容积占预计值百分比成正相关,而且,肺泡毛细血管膜弥散量与各指标的相关性最好。结论:随着慢性阻塞性肺病程度的加重,一氧化碳弥散量、肺泡毛细血管膜弥散量和肺泡毛细血管血量均有下降。肺泡毛细血管膜弥散量的异常比一氧化碳弥散量和肺泡毛细血管血量较早出现而且较严重。肺泡毛细血管膜弥散量的测定可以监测疾病发展并早期发现慢性阻塞性肺病气体交换的异常。     

Early post-traumatic seizures in children: Clinical and radiological aspects of injury

Objective : To determine the type and outcome of early post-traumatic seizures in children and the factors associated with it.
Methodology : A prospective observational study on all consecutive children with head injuries at the General Hospital Kuala Lumpur between November 1993 and December 1994. The onset, type and frequency of seizures occurring within the first week of injury were documented. Using inpatients as a cohort, logistic regression analysis was used to determine clinical and radiological variables significantly associated with seizures. The outcome 6 months post-injury was assessed using the Glasgow Outcome Scale.
Results : Fifty-three of 966 children (5.5%) developed seizures within the first week of trauma. Seven (13.2%) occurred within 1 h of injury, 30 (56.6%) between 1 and 24 h and 16 (30.2%) after 24 h. Factors significantly associated with early post-traumatic seizures were female sex, age less than 2 years, loss of consciousness for more than 24 h and acute subdural haematoma ( P <0.01). Children with seizures had a poorer outcome (death or severe disability) man inpatients without seizures (21/53 vs 19/182, P <0.001). The outcome was worst in children with recurrent partial seizures, who had a longer injury-seizure interval and were more likely to have focal neurologic deficits compared to those with sporadic or generalized seizures.
Conclusions : Anticonvulsant prophylaxis to minimize the adverse effects of early seizures in head injury should be considered for young children (less than 2 years old) with subdural haematoma and a prolonged duration of coma. Prompt and effective control of recurrent seizures is recommended.