Osteo-progenitors in vascular calcification: a circulating cell theory

Vascular calcification has been associated with the incidence of cardiovascular events and thus there has been interest in better understanding its pathogenesis. Early theories considered vascular calcification to be a passive process which occurred as a non-specific response to tissue injury or necrosis. More recent theories propose vascular calcification results from loss of molecular inhibitors or via an active cell mediated process. The origin of the cells responsible for vascular calcification is controversial and may vary in different sites and patients. Calcification has been reported as result of apoptosis or death of vascular smooth muscle cells for example. One novel source of cells controlling vascular calcification is from the bone marrow. A circulating immature bone marrow derived population has been identified and a small subset of this bone marrow population has been reported to possess bone forming properties in vitro and hence termed osteo-progenitors. This article reviews evidence supporting the contribution of these naive bone marrow derived circulating osteo-progenitor cells in vascular calcification.     

Subpopulations of fetal-like gingival fibroblasts: characterisation and potential significance for wound healing and the progression of periodontal disease

Wound healing in the adult is commonly compromised by excessive scar formation. In contrast, fetal wound healing is a regenerative process characterised by the conspicuous absence of scarring. Available evidence suggests that phenotypic differences between fetal and adult fibroblasts are important determinants of these distinct modes of tissue repair. In this context, a number of groups (including our own) have documented differences between fetal and adult fibroblasts with respect to such potentially relevant characteristics as migratory activity, motogenic response to cytokines and the synthesis of motility factors, cytokines and matrix macromolecules. The oral mucosa appears to be a privileged site in the adult in that it continues to display a fetal-like mode of wound healing. Data are presented in this review indicating that a subpopulation of gingival fibroblasts expresses several 'fetal-like' phenotypic characteristics. These observations are discussed in terms of both the continued expression of a fetal-like mode of wound healing in the oral mucosa and the possible differential involvement of distinct fibroblast subpopulations in the progression of periodontal disease.     

大鼠脂肪和骨髓来源间充质干细胞基本生物学特征的比较

目的:分离大鼠脂肪和骨髓来源的间充质干细胞,比较两种间充质干细胞的生物学特征。方法:实验于2003-09/2006-11在广州市第一人民医院、湘雅医院中心实验室完成。取SD大鼠的股骨、胫骨、肱骨及腹股沟处脂肪垫进行骨髓间充质干细胞与脂肪间充质干细胞的分离。将骨髓间充质干细胞和脂肪间充质干细胞在含10%血清,1%双抗的低糖DMEM培养基,37℃、体积分数为0.05的CO2条件下进行培养。在细胞达到80%～90%融合时,使用0.25%胰酶消化传代。传代至第3代使用倒置显微镜观察骨髓和脂肪两种不同来源细胞的传代后的形态、贴壁、生长增殖、集落等情况。取消化传3代的两种细胞分别制成单细胞悬液进行细胞贴壁率的检测,贴壁率=贴壁细胞总数/接种细胞总数×100%。取第2代和第5代骨髓间充质干细胞和脂肪间充质干细胞以1×107L-1密度培养。每天同一时间,随机抽取5孔细胞,加入5%噻唑兰20μL/孔,培养4～6h,吸出孔内液体,每孔加150μL二甲基亚砜震荡10min,酶联免疫测定仪测定波长490nm处的吸光度,取5孔吸光度的均值,以时间为横坐标,吸光度值为纵坐标,绘制生长曲线。采用流式细胞仪检测细胞表面CD29、CD34、CD44标记,免疫化学检测细胞CD29、CD34、CD44。结果:①在单位质量骨髓和脂肪组织中获得的间充质干细胞数量相当。两种细胞形态均为条索样,呈成纤维细胞形态。②应用直线相关分析,考察骨髓贴壁率与脂肪贴壁率之间的关系,相关系数r=0.999,决定系数r2=0.997(F=5862.949,P<0.001),两贴壁率之间有直线相关关系,不同的时间点两种细胞的贴壁率相似,并且有同向变化的趋势。③脂肪间充质干细胞的增殖能力与骨髓间充质干细胞相当。④脂肪间充质干细胞和骨髓间充质干细胞表面表达CD29、CD44,不表达CD34。结论:自大鼠脂肪中可提取出与骨髓间充质干细胞生物学特征类似的脂肪间充质干细胞。     

纳米羟基磷灰石对人骨髓基质干细胞体外成骨活性的影响

目的：观察人骨髓基质干细胞在纳米羟基磷灰石材料上的生长、分化特点以及成骨细胞形态. 方法：实验于2004-03/2005-07在中南大学湘雅医院医学实验室完成.①实验方法：采用密度梯度离心的方法分离人骨髓基质干细胞,加入含体积分数为0.1的新生牛血清的低糖DMEM完全培养基中作原代培养,细胞长至90%汇合时传代,取培养第3代细胞接种于纳米羟基磷灰石（卫生部肝胆肠研究中心纳米课题组提供）表面,并加入含1 mmol/L地塞米松、50 mg/L维生素C、10 mmol/L β-甘油磷酸钠的培养基中诱导分化、培养.②观察指标：复合培养第2,4,6,8天后采用MTT法检测细胞增殖情况;复合培养7 d后行钙-钴法成骨细胞染色观察细胞分化情况;培养8 d后应用扫描电子显微镜观察细胞在材料上的生长情况. 结果：MTT法检测出的吸光值随着培养时间的增加而增大（P＜0.05）;经加入特定的成骨诱导体系培养7 d后,附着于材料的骨髓基质干细胞具有典型的成骨细胞形态,经钙-钴法染色后细胞胞浆中可见灰黑色颗粒或块状沉淀的阳性反应,细胞形态也多呈多角形或短矩形;培养8 d后扫描电镜可观察到材料孔隙内有细胞长入. 结论：人骨髓基质干细胞在纳米羟基磷灰石材料上生长良好,提示纳米羟基磷灰石适于骨髓基质干细胞的生长、分化,可作为骨组织工程的细胞外支架材料.     

大鼠肾脏髓质外皮质组织低氧诱导因子1α在常压模拟高住低练环境中的表达变化

目的:探讨常压模拟高住低练对肾脏髓质外皮质组织低氧诱导因子1α表达的变化。方法:实验于2005-11/2006-07在湖南师范大学体育学院生化实验室、分子实验室及湖南省肿瘤医院分子实验室完成。①实验材料:清洁级8周龄雄性SD大鼠60只,体质量为(200±20)g。②实验分组:60只SD大鼠随机分成两大组:对照组和运动组。其中对照组分为常氧组、高住8h组和高住12h组;运动组分为常氧运动组、高住8h运动组和高住12h运动组,每小组10只。③实验干预:常氧运动组、高住8h运动组、高住12h运动组大鼠每天在坡度为0的动物跑台上以25m/min的速度训练1h。训练完后,将高住8h组、高住8h运动组和高住12h组、高住12h运动组放入体积分数为0.125的低氧(相当于海拔4000m)舱内分别休息8h和12h。训练共4周,5d/周。④实验评估:用免疫组织化学法检测各组大鼠肾脏髓质外皮质组织低氧诱导因子1α表达。结果:60只SD大鼠进入结果分析。低氧诱导因子1α蛋白表达的变化阳性单位值越大,表示低氧诱导因子1α阳性产物蛋白表达越强烈;高住8h组、高住12h组、常氧运动组低氧诱导因子1α蛋白表达值均大于常氧组,差异具有显著性意义(P<0.05);高住8h运动组、高住12h运动组分别与常氧运动组比较,差异均无显著性(P>0.05);高住8h运动组低氧诱导因子1α蛋白表达值明显低于高住12h运动组,差异有显著性意义(P<0.05)。结论:模拟高原环境、高住低练训练均能诱导SD大鼠肾脏低氧诱导因子1α的表达,以低氧12h训练组低氧诱导因子1α的表达最高。     

Inactivation of Friend erythroleukemia virus and Friend virus- transformed cells by merocyanine 540-mediated photosensitization

The Friend virus complex was used as a model to study the effects of merocyanine 540 (MC 540)-mediated photosensitization on enveloped viruses. Simultaneous exposure to the lipophilic dye MC 540 and white light inactivated cell-free virus, cell-associated virus, and virus- transformed cells. When used under experimental conditions that are known to preserve most mature blood cells, at least some coagulation factors, and a significant portion of the pluripotent hematopoietic stem cell compartment, MC 540-mediated photosensitization reduced virus titers by greater than or equal to 4 log and the concentration of in vitro clonogenic erythroleukemia cells by greater than or equal to 5 log. Animals that received a single intravenous injection of photosensitized virus were resistant to a subsequent challenge with live virus. High sensitivity to MC 540-mediated photosensitization appears to be a property that is shared by other enveloped viruses. Thus, photosensitization mediated by MC 540 may be of benefit in the sterilization of blood products (in particular, cellular products), the production of vaccines, and selected areas of antiviral therapy.     

脐血干细胞转化为肝细胞的研究进展

自进行第1例脐血干细胞移植以来,各国科研机构相继开展对于脐血干细胞的研究,脐血库也纷纷建立．随着再生医学的发展,众多国内外学者在尝试进行非肝源性细胞向肝细胞分化方面的研究,并已经证实脐血干细胞在特定的微环境下可以在体内和体外转化为肝样细胞,为脐血干细胞在肝脏疾病中的应用奠定了基础．本文就脐血干细胞向肝细胞转化的最新研究进展作一综述．     

Toxicity induced by nanoparticles

Nanoparticle research is currently an area of intense scientific interest due to a wide variety of potential applications. Human beings have been exposed to airborne nanosized particles throughout their evolutionary stages, and such exposures have increased dramatically over the last century. Nanoparticle can modify the physicochemical properties of the material as well as create the opportunity for increased uptake and interaction with biological tissues through inhalation, ingestion, and injection. This combination of effects can generate adverse biological effects in living cells. Nanoparticles have proved toxic to human once in the blood stream, nanoparticles, spleen, bone marrow and nervous system can be transported around the body and be taken up by organs tissue and cell cultures, resulting in increased oxidative stress, inflammatory cytokine production and cell death. Unlike larger particles, nanoparticles may be taken up by cell mitochondria and the cell nucleus studies demonstrate the potential for nanoparticles to cause DNA mutation and induce major structural damage to mitochondria, even resulting in cell death. Size is therefore a key factor in determining the potential toxicity of a particle. How these nanoparticles behave inside the body is still a major question that needs to be resolved. There is a responsibility to test and optimize these new nanomaterials early during the development process to eliminate or ameliorate identified toxic characteristics.     

How to obtain excellent response rates when surveying physicians

This paper outlines ways to maximize response rates to surveysby summarizing the most relevant literature to date and demonstratinghow these techniques have resulted in consistently high ratesof return in family practice research. We describe the methodologyused in recent surveys of physicians conducted by the Centrefor Studies in Family Medicine through its Thames Valley FamilyPractice Research Unit, located in London, Ontario, Canada andfunded by the Ontario Ministry of Health and Long-Term Care.The identification and implementation of these techniques tomaximize response rates is critical, as primary health careresearchers often rely on information gathered through questionnairesto study physicians' practice profiles, experiences and attitudes.Four separate and distinct mailed surveys of physicians usinga modified Dillman approach were conducted from 2001 to 2004.The sampling strategies, topics, types of questions and responseformats of these surveys varied. The first survey did not useany incentives or recorded delivery/registered mail and receiveda response rate of 48%. In sharp contrast, the other three surveysobtained responses rates of 76%, 74%, 74%, respectively, achievedthrough the use of gift certificates and recorded delivery/registeredmail. Sending a survey by recorded delivery/registered mailtends to result in the survey package being given priority inthe physicians' incoming mail at the practice. Gift certificatespartially compensate physicians for time spent completing thesurvey and recognition of the time required is appreciated.The response rates achieved provide strong evidence to supportthe use of monetary incentives and recorded delivery/registeredmail (along with the Dillman approach) in survey research. Itis anticipated that this evidence will be used by other researchersto justify requests for funding to cover the costs associatedwith incentives and recorded delivery/registered mail. We recommendthe use of these strategies to maximize response rates and improvethe quality of this type of primary health care research. Keywords. Response rates, surveys, physicians.