Studies with a pathogenic and an attenuated strain of Venezuelan equine encephalitis virus and aedes aegypti (L.) mosquitoes

Summary Venezuelan equine encephalitis virus was passaged in KB cell cultures. The virus lost its mouse pathogenicity following subcutaneous inoculation during KB cell passage; the attenuated strain also produced smaller plaques than the pathogenic strain. Both strains grew to the same extent inAedes aegypti (L.) mosquitoes after intrathoracic inoculation. If any reversions to pathogenicity occur during development of the attenuated virus in mosquitoes, then the mutation frequency per duplication per particle must be smaller than 3.5×10^–6.     

Mechanisms of Neuronal Death in Alzheimer's Disease

Recent data in cell culture has shown that brain neurons are particularly vulnerable to degeneration by apoptosis. Further the inducers that activate the program (e.g. β-amyloid, oxidatative damage, low energy metabolism) correspond to conditions present in the Alzheimer's disease (AD) brain. This suggests the possibility that apoptosis may be one of the mechanisms contributing to neuronal loss in this disease. Indeed, some neurons in vulnerable regions of the AD brain show evidence of DNA damage, nuclear apoptotic bodies, chromatin condensation, and the induction of select genes characteristic of apoptosis in cell culture and animal models. This suggests the existence of apoptosis in the AD brain, a hypothesis also consistent with evolving research in one of the regulatory functions of the presenilin genes. On the other hand, DNA damage is present in the majority of neurons in vulnerable regions in early and mild cases. In most tissues, cells in fully activated apoptosis degenerate and are removed within hours to days and thus it seems all DNA damage is unlikely to signify terminal apoptosis. The presence of extensive DNA damage suggests an acceleration of damage, faulty repair process, loss of protective mechanisms, or an activation and arrest of aspects of the apoptotic program. DNA damage is unlikely to be an artifact of postmortem delay or agonal state. The existence of protective mechanisms for neurons may exist as these cells are nondividing and essential. In this context it is interesting that Bcl-2 is upregulated in most neurons with DNA damage. Further, at least one DNA repair enzyme is also upregulated. Thus it appears as if neurons are in a struggle between degeneration and repair. As research advances it is critical to reduce the stimuli that cause the neuronal damage and discover the key intervention points to assist neurons in the repair processes.     

Histiocytoid hemangioma of the heart with peripheral eosinophilia

A histiocytoid hemangioma of the heart is reported, which was found incidentally in a man with unusually high eosinophilia. The eosinophilia subsided dramatically following removal of the tumor. The "histiocytoid" or the "epithelioid" appearance of the tumor cells and the presence of vacuolated cells were the characteristic microscopic features. The endothelial origin of this tumor was verified by positive immunostaining for factor VIII-related antigen and ultrastructural demonstration of intracytoplasmic lumen formation, abundant cytoplasmic filaments, pinocytotic vesicles, and prominent basal lamina. The presence of mitotic activity, cellular pleomorphism, and tumor necrosis raised the possibility of its malignant potential. The occurrence of this tumor in the heart may be mistaken for a myxoma clinically and a metastatic carcinoma pathologically.     

Employment Consequences of COVID-19 for People with Disabilities and Employers

Journal of Occupational Rehabilitation - Purpose The COVID-19 pandemic has disproportionately affected the lives of people with disabilities (PWD). How the pandemic affects the employment of PWD...     

异丙酚麻醉下行钳刮术82例临床观察

目的 :探讨异丙酚麻醉下行孕 10～ 13周钳刮术镇痛效果及安全性。方法 :应用异丙酚静脉给药麻醉后钳刮 (观察组 )。与无任何镇痛方法钳刮 (对照组 )。结果 :观察组与对照组在宫口松驰度 ,手术时间 ,出血量方面相比无明显差异 (P >0 .0 5 ) ,人工流产综合征发生率观察组 0 ,对照组 5 9%。结论 :异丙酚麻醉下行钳刮术能安全镇痛 ,避免人流综合征的发生     

大鼠磨牙三维有限元模型的建立

目的 :建立大鼠磨牙的三维有限元模型 ,探讨牙及牙周组织的应力分布状况。方法 :采用Sprague Dawley大鼠 2 0只 ,建立大鼠磨牙正畸移动的动物模型 ,制作大鼠上颌第一磨牙牙周连续切片 ;采用计算机技术 ,重建牙及牙周组织三维形态、结构 ,并建立其三维有限元模型。结果 :组织切片的应力分布显示牙周膜是一种存在于两种硬组织之间的软组织 ,有其特有的应力分布状态。结论 :本研究建立的正畸大鼠磨牙三维有限元模型是观察正畸牙移动过程中分析应力的一种简便、准确、可靠的模型及方法。