云南省19县市小兽体表蚤类的生态位研究

对云南省19县市小兽体表蚤类生态位进行研究,并初步探讨两者间协同进化关系。采用Levins模型和Cowell-Futuymas模型分别测定47种小兽体表部分主要蚤种的生态位宽度和生态位重叠指数。生态位宽度最宽的是特新蚤（0.0987）,其次是近端远棒蚤二刺亚种（0.0749）、低地狭臀蚤（0.0734）,最窄的为伍氏病蚤（0.0216）。方叶栉眼蚤与近端远棒蚤二刺亚种生态位重叠指数最高（0.5）,与伍氏病蚤的重叠指数最低（0.0021）。印鼠客蚤与缓慢细蚤生态位重叠指数最高（0.8660）,与无值大锥蚤最低（0.0048）。蚤类生态位宽度值低,表明其与宿主动物之间的协同进化程度相对较高;生态位宽度值高,表明其与宿主动物之间的协同进化程度较低。两种蚤的生态位重叠值高,表明其在宿主选择上趋于相同或相近;反之,则差异较大。生态位宽度可以作为蚤类与其宿主动物间协同进化的一个判定指标。     

Rejuvenation of aged hematopoietic stem cells

Until recently, there was broad consensus in the stem cell aging field that the phenotype of aged hematopoietic stem cells (HSCs) is fixed—dominated by cell-intrinsic regulatory mechanisms that cannot be altered by pharmacological or genetic means. The conventional thinking was that HSC aging could not be reverted by therapeutic intervention. This paradigm has started to shift dramatically, primarily because hallmarks of aged HSCs have been successfully reverted by distinct experimental approaches by multiple laboratories. We will discuss in this review these hallmarks of HSCs aging and the novel approaches that successfully ameliorated or even reverted aging-associated hallmarks of aged HSCs.     

Skeletal stem cells: phenotype, biology and environmental niches informing tissue regeneration

Advances in our knowledge of the biology of skeletal stem cells, together with an increased understanding of the regeneration of normal tissue offer exciting new therapeutic approaches in musculoskeletal repair. Skeletal stem cells from various adult tissues such as bone marrow can be identified and isolated based on their expression of a panel of markers associated with smooth muscle cells, pericytes and endothelial cells. Thus, skeletal stem cell-like populations within bone marrow may share a common perivascular stem cell niche within the microvascular network. To date, the environmental niche that nurtures and maintains the stromal stem cell at different anatomical sites remains poorly understood. However, an understanding of the osteogenic and perivascular niches will inform identification of the key growth factors, matrix constituents and physiological conditions that will enhance the ex vivo amplification and differentiation of osteogenic stem cells to mimic native tissue critical for tissue repair. This review will examine skeletal stem cell biology, the advances in our understanding of the skeletal and perivascular niche and interactions therein and the opportunities to harness that knowledge for musculoskeletal regeneration.     

剑川鼠疫自然疫源地27种蚤类生态位研究

本文运用生态位理论和模糊聚类，对云南省剑川鼠疫自然疫源的２７种蚤类的生态位进行了研究，三维生态位最宽的是特新蚤，其次是斯氏新蚤，再次是人蚤；三维生态位元素多样性和均匀性最高的是特新蚤，其次是斯氏新蚤，这反映出这３种蚤的三维生态位元素结构和利用性差异较突出。将这２７种蚤划分为９个竞争性群，揭示了各种蚤之间的资源利用或适应模式的关系。这种模式不仅反应了各蚤之间的生态相似性，还在一定程度上反映了由资源利     

The Brucellae and Their Success as Pathogens

Brucellae are tiny, aerobic, slow growing, catalase and oxidase positive Gram negative coccobacilli or small rods, which may reach man through exposure to tissues of mammalian hosts via cuts or aerosols, or as food infections mostly through dairy products. As parasites brucellae are extraordinarily successful, causing very long-lasting infections in all mammalian social animals, such as ungulates, canids, and rodents; recently they have been found to also cause disease in pinnipeds and cetaceans. Brucellae as members of the alpha Proteobacteria, have suffered major losses of genomic material as they adapted to their facultative intracellular parasite role, and are able to initiate infection with minimal disturbance of the innate immune system, thus reaching a privileged intracellular niche where they multiply. Brucellae are likely to be among the toughest organisms to control through public health and agricultural policies, even involving detection-slaughter strategies.     

基于小生境混合遗传算法的文本特征词聚类研究

提出一种基于小生境混合遗传算法的文本特征词聚类方法.该方法首先采用贝叶斯语义模型对语料库进行统计分析,并以K-L距离度量特征词间的距离,然后将小生境遗传算法与K-Means算法相结合,对文本特征词进行聚类,为文本特征词聚类提供了较高的效率和精确度.实验表明该方法是一种高效可行的文本特征词聚类方法.     

Mechanisms of hematopoietic stem cell aging

New blood cells are continually produced from the hematopoietic stem cells (HSCs) that reside in the bone marrow. Throughout the life-span of the organism, this stem cell reservoir sustains life. Although HSCs can persist in vivo longer than one life-span (Harrison et al., 1978), with aging, HSC regenerative potential diminishes and skewing from lymphopoiesis toward myelopoiesis occurs. The expansion in the HSC pool with aging provides sufficient, yet abnormal, blood production. Examination of gene expression changes in aged HSCs has provided a link between aging and genomic instability. Furthermore, studies on the effects of reactive oxygen species (ROS) on HSC aging has given more insight into the reasons for HSC failure. Understanding of the interactions between niche cells and HSCs and changes in them with aging, may give us insights into the lineage skewing phenotype observed in the aged, and also other immune dysfunctions.     

糖尿病大鼠与正常大鼠胰腺干细胞增生能力的比较研究

目的 比较糖尿病大鼠与正常大鼠胰腺干细胞的增生能力,探讨大鼠胰岛损伤的微环境对干细胞的影响.方法 60mg/kg链脲霉素腹腔注射SD大鼠制备糖尿病大鼠模型为实验组(10只)及正常SD大鼠为对照组(10只),取实验组和对照组胰腺修剪消化成单细胞后接种于培养板中培养;取传代第3代细胞行Nestin免疫组化鉴定;观察细胞生长曲线,取培养至第3代及第7代的细胞以流式细胞术测定细胞周期.结果 实验组和对照组大鼠胰腺细胞传代后Nestin免疫组化鉴定证实为胰腺干细胞,糖尿病大鼠胰腺干细胞早期增生能力强[S期细胞所占比率:(20.7±2.7)%vs(14.1±2.5)%,P＜0.05],传代时间明显较对照组大鼠短[第3代传代时间:4.6±0.5天vs 7.7±0.6天,P＜0.05],但第6代以后传代时间趋向一致[第6代传代时间:8.4±0.5天vs8.0±1.0天,P＞0.05].结论 大鼠胰腺胰岛损伤后可刺激干细胞增生,干细胞增生能力的变化与微环境有关.     

Prevalence of co-infection between respiratory syncytial virus and influenza in children

Background

Respiratory syncytial virus (RSV) and influenza have varying degree of seasonal overlap.