制作角膜缘干细胞完全缺乏动物模型的新方法

目的提出一种新的角膜缘干细胞完全缺乏模型制作方法,为干细胞缺乏疾病的治疗性研究提供可靠的模型。方法利用9mm环钻划界,板层切除角膜组织,通过临床评分、印迹细胞学、组织病理及免疫组织化学验证模型的成功。结果板层切除术后30~45d,模型眼角膜混浊、上皮缺损、大量新生血管长入,印迹细胞学可见PAS( )的杯状细胞,组织病理学检查上皮符合结膜细胞表型,免疫荧光染色可见结膜杯状细胞特异性标志MUC5AC阳性表达。结论环钻划界加板层切除法为一种可靠、有效的角膜缘干细胞完全缺乏模型制作方法。     

Etomidate for Rapid-sequence Intubation in Young Children: Hemodynamic Effects and Adverse Events

OBJECTIVES: Physicians commonly use etomidate for adult rapid-sequence intubation (RSI), but the manufacturer does not recommend its use for children under 10 years of age due to a lack of data. The authors present their experience with etomidate for pediatric RSI in order to further develop its risk-benefit profile in this age group. METHODS: Trained abstractors reviewed the medical records for all children under 10 years old who received etomidate for RSI between July 1996 and April 2001. RESULTS: 105 children, with an average age of 3 (+/-2.9) years, received a median dose of 0.32 (+/-0.12) mg/kg of etomidate. The systolic blood pressure increased an average of 4 mm Hg (95% CI = -3.3 to 9.2); the diastolic blood pressure increased 7 mm Hg (95% CI = -3.1 to 11) within 10 minutes of receiving etomidate. The heart rate increased an average of 10 beats/min (95% CI = 4.0 to 17.4). Complications included three patients who vomited within 10 minutes of etomidate administration. There were no cases of documented myoclonus, status epilepticus, or new-onset seizures. Thirty-eight patients received corticosteroids during the hospital course, none for suspected adrenal insufficiency. Three patients died, all from severe brain injury. CONCLUSIONS: In children less than 10 years old, etomidate seems to produce minimal hemodynamic changes, and appears to have a low risk of clinically important adrenal insufficiency, myoclonus, and status epilepticus. The association between etomidate and emesis (observed in less than 3% of enrolled patients) remains unclear. For clinical situations in which minimal blood pressure changes during RSI are critical, etomidate appears to have a favorable risk-benefit profile for children under 10 years old.     

Therapeutic effect of antimicrobial drugs against experimental infections due toYersinia pestis in mice

Although there are effective antibacterial agents against plague, newer antibacterial agents have been developed which show more potent activity against other bacterial organisms, but have not been tested againstYersinia pestis. A strain ofYersinia pestis was selected (no. 22; National Institute of Infectious Diseases, Tokyo, Japan) that caused a systemic infection in mice.Y. pestis no. 22 was intraperitoneally inoculated into DDY-strain mice, and 13 oral or 6 injectable antibacterial drugs given to the infected mice at varying doses 1 and 24 hours after infection. Levofloxacin, sparfloxacin and ofloxacin were the most effective oral agents against the infection, and prulifloxacin and pazufloxacin were also effective but to a lesser extent. Also, gentamicin and arbekacin were the most potent injectable antibacterial agents againstY. pestis. These results suggest that there are several new drugs, both oral and injectable, which exert excellent in vivo antibacterial activity against a mouse infection model and may be useful for the clinical treatment of plague.     

Preventing heart disease: is treating the high risk sufficient?

Monte Carlo simulation was used to assess the effects of several intervention strategies on coronary heart disease mortality rates in a Finnish and a North American cohort. Lowering total serum cholesterol by 4%, smoking by 15%, and diastolic blood pressure by 3% for the whole cohort would be expected to reduce the incidence of non-fatal myocardial infarction by at least 13% and coronary heart disease deaths by at least 18%. Lowering serum cholesterol by 34%, diastolic blood pressure to 90 mmHg, and reducing smoking by 20% in the subset of the population with all three risk factors in the highest quartile would result in a 6-8% reduction in non-fatal myocardial infarction and a 2-9% reduction in deaths from coronary heart disease in these cohorts. These data demonstrate that in populations with a relatively high incidence of heart disease, treating the entire population will produce larger effects than focusing only on high-risk populations.     

Segregation analysis of leprosy in families of northern Thailand

Sixty-three families with multiple instances of leprosy were identified through a major leprosy treatment center in northern Thailand. Complex segregation analyses for single major genes or polygenic inheritance were performed using the maximum-likelihood routine POINTER to determine the most likely etiologic model of genetic susceptibility. Liability differences between men and women were considered in these models. When individuals were considered to be affected because they had any form of leprosy, a generalized major gene model with nearly dominant parameters on the liability scale, but additive penetrances, was found to be the most likely. When only those individuals who had tuberculoid forms of leprosy were considered to be affected, a recessive model was found to be the most likely; however, the discrimination between various models was poor. Further analyses are necessary to delineate genetic mechanisms to explain these apparently divergent results. In particular, methods of testing two locus models should be considered.     

豚鼠耳蜗微血管内皮细胞体外通透性的研究

目的　研究豚鼠耳蜗微血管内皮细胞的体外通透性特征。方法　在成功建立豚鼠耳蜗微血管内皮细胞体外通透性模型的基础上 ,研究该体外模型跨细胞电阻及对12 5I 牛血清白蛋白的通透性。结果　①耳蜗微血管内皮细胞在培养增殖过程中其跨细胞电阻呈动态变化过程 ,以 5× 10 4/cm2 的细胞密度接种时 ,7d左右电阻到达峰值 ,其跨细胞电阻峰值大小为 (118 9± 18 5 )Ω/cm2 ;②体外模型中加入12 5I 牛血清白蛋白后 ,其通透性呈上升期抛物线型曲线 ,90min内几乎呈直线。结论　跨细胞电阻及对12 5I 牛血清白蛋白变化曲线能反映体外耳蜗微血管内皮细胞的通透性特征     

溴氰菊酯对白纹伊蚊（Aedesalbopictus）C6／36细胞株的细胞遗传学效应

本研究选择１０μｇ／ｍｌ、２０μｇ／ｍｌ、４０μｇ／ｍｌ浓度的溴氰菊酯处理白纹伊蚊Ｃ６／３６细胞，以ＭＭＣ作为阳性对照物，观察溴氰菊酯处理２４ｈ后对Ｃ６／３６细胞染色体畸变率和姐妹染色单体互换（ＳＣＥ）频率的影响。结果显示，三个浓度的溴氰菊酯对Ｃ６／３６细胞染色体畸变率均没有显著影响（Ｐ＜０．０５）；溴氰菊酯浓度在４０μｇ／ｍｌ时可诱导Ｃ６／３６细胞ＳＣＥ频率轻度增高（Ｐ＞０．０５），而溴氰菊酯浓度在１０μｇ／ｍｌ、２０μｇ／ｍｌ时，对Ｃ６／３６细胞ＳＣＥ频率没有诱导作用。表明溴氰菊酯对Ｃ６／３６细胞的遗传学效应较弱     

Neuropathology of ALS: Spheroids

I briefly review spheroids observed in the anterior horns of the spinal cord in amyotrophic lateral sclerosis (ALS). Spheroids are argentophilic bodies more than 20 μm in diameter. Recently, some connections between the proximal axonal swellings including spheroids and the perikarya have been reported in some ALS patients with a short clinical course or mild depletion of anterior horn neurons. Most of the cell bodies directly connected with the axonal swellings appear normal, and spheroids are considered to be one of the hallmarks of the early histological changes in this disorder. Spheroids are strongly positive with anti-phosphorylated neurofilament antibody, and are also positive with calcitonin gene-related peptide and anti-peripherin antibody. Some spheroids are immunostained with anti-synaptophysin antibody and anti-ubiquitin antibody. Spheroids are not immunostained with anti-phosphorylated tau antibody, or high molecular weight microtubule associated proteins. Electron microscopically, spheroids are usually composed of densely packed accumulation of 10 nm neurofilaments with a variety of orientations, plus vesicles, dense bodies and mitochondria. When the swellings of the initial segment is relatively pronounced, the undercoating is obscured and the neurofilaments become interwoven in some parts. In the first internode of the myelinated axons, as the swellings become larger, the neurofilaments lose their parallel orientation and become intermingled. Large accumulation of neurofilaments resembling spheroids in the perikarya of large anterior horn cells suggests that spheroids could be derived not only from the axon including the proximal portion, but also from the perikarya. Structures apparently identical to axonal spheroids are observed at the light and electron microscopic levels in the proximal portion of axons of anterior horn cells in animal models intoxicated with β, β'-iminodipropionitrile (IDPN), or with aluminum, in hereditary canine spinal muscular atrophy (HCSMA). The pathogenetic mechanism is probably associated with an impairment in slow axonal transport which particularly affects the neurofilaments in IDPN and aluminum intoxication. Impairment of slow axonal transport of neurofilaments also plays an important role in the pathogenesis of ALS. The average diameter of even normalappearing initial segment is larger in ALS than in the controls. The perikarya connected with the swollen proximal axons and their dendrites almost always appear normal. These findings suggest that the slow axonal transport of neurofilaments is probably impaired in this portion of the axon at an early stage in ALS as well as animal models for human ALS. However, techniques to analyze slow axonal transport in humans still remain tobe developed. Recently, overexpression of neurofilament subunits in transgenic mice produces a condition resembling ALS. The transgenic model may offer an interesting perspective not only for testing therapeutic strategies but also for investigating in a systematic way the various genetic and environment factors controlling the onset and progression of the disease and might yield new insights on the etiology of ALS.     

Effects of repeated doses of benzodiazepines on arterial blood gases and transcutaneous Po2

The effects of repeated doses of benzodiazepines, diazepam and midazolam in combination with meperidine on arterial blood gases and transcutaneous PO2 were studied in eight healthy volunteers. The study was designed to mimic a clinical situation. Initially two doses of either midazolam 0.05 mg/kg or diazepam in fat emulsion 0.15 mg/kg were given in a randomized crossover fashion with a 20-min interval, followed by meperidine 0.5 mg/kg another 20 min later. The opioid effects were then antagonized by naloxone 0.4 mg. The initial doses of benzodiazepines caused an increase in PaCO2 and a decrease in PaO2. The changes in PaO2 were of short duration and recovered to baseline levels between injections. However, they came sooner and were more pronounced after midazolam. The changes in PtcO2 paralleled those in PaO2. The PtcO2 index as a measure of cardiac output and peripheral blood flow adequacy was increased immediately after the first injection of midazolam but was otherwise not different from control. There were no differences between the drugs concerning PtcO2 index. PaCO2 increased after the first benzodiazepine injection and remained so throughout the study. Addition of meperidine caused only small changes in PaO2 and PaCO2. These changes were reversed by naloxone. In spite of different elimination kinetics there was no difference in the duration of respiratory depression between the two benzodiazepines.     

大蒜素对脑局灶缺血大鼠血小板活化功能及其结构的影响

目的：观察大蒜素对脑局灶缺血大鼠血小板活化功能或轻药物诱导的血小板活化功能及其结构的影响。方法：（1）将SD大鼠随机分为（空白组、大蒜素大剂量组和小剂量组）3组，于末次给予试药1．5h后颈总动脉插管取血，加入诱导剂二磷酸腺苷（ADP）或胶原，测定血小板最大聚集率；（2）采用化学刺激（FeCl3)诱导血栓闭塞法制备大鼠急性大脑中动脉血栓模型，随机分为（假手术组、模型组、大蒜素大剂量组和小剂量组）4组，给药方法同实验（1），颈总动脉插管取血后分离血浆，测定血浆血栓烷B2（TXB2）、6－酮－前列腺素F1α(6-keto-PGF1α）含量；（3）加入ADP孵育激活性，离心得到血小板沉淀块，透射电镜下观察血小板的超微结构。结果：与空白组或模型组相比，大蒜素大剂量组（10mg/kg)、小剂量组（5mg/kg)均可显著抑制药物诱导的血小板聚集（P＜0．01），且大剂量组显著优于小剂量组（P＜0．05）；均可明显降低模型大鼠血浆TXB2的含量，降低TXB2／6－keto-PGF1α比值，大剂量组还显著升高血浆中6－keto-PGF1α水平（P＜0．05，P＜0．01）；可明显抑制血小板活化过程中超微结构的改变，且有一定的量效关系。结论：大蒜素可能通过抑制血小板聚集，抑制血小板活化时大量释放的活性肽TXA2、促进恢复TXA2／PGI2平衡，抑制血小板激活释放过程中超微结构的改变，从而对脑梗塞起治疗作用。