睾酮对衰老心肌细胞的干预作用及其机制

目的探讨不同剂量睾酮对衰老心肌细胞的干预作用及其可能机制。方法将心肌细胞随机分为正常组、衰老组、1μmol/L睾酮组、100 nmol/L睾酮组、10 nmol/L睾酮组,检测各组心肌细胞周期分布,去磷酸化视网膜母细胞瘤蛋白(RB)表达,细胞内活性氧水平以及细胞线粒体DNA突变率。结果衰老组心肌细胞G_0/G_1期比例较正常组明显升高,而1μmol/L睾酮组、100 nmol/L睾酮组、10 nmol/L睾酮组G_0/G_1期比例较衰老组明显降低(P<0.05)。除10 nmol/L睾酮组对RB表达无明显影响外,睾酮干预可下调去磷酸化RB表达,降低细胞内活性氧水平,降低线粒体DNA突变率(P<0.05,P<0.01)。结论睾酮可抑制小鼠心肌细胞衰老,这一作用部分是通过下调去磷酸化RB表达,降低细胞内活性氧水平,降低线粒体DNA突变率来实现的。     

灵芝多糖抗H2O2诱导的HDF细胞衰老及其机制的研究

目的 探讨不同剂量灵芝多糖(GLP)对抗H2O2诱导的HDF细胞衰老及可能的细胞周期调控机制.方法 将HDF细胞培养至24代时分成6组:即青年组、对照组、衰老模型组及GLP小剂量(50 mg/L)、中剂量(100 mg/L)、大剂量(150 mg/L)组,体外DMEM培养,各GLP组和衰老模型组自30代始添加 H2O2诱导HDF细胞衰老,直至38代.采用MTT法检测细胞活力;Dimri法检测β-半乳糖苷酶活性;RT-PCR法检测p16INK4a、CyclinD1、CDK4的表达;Western印迹法检测Rb蛋白表达和磷酸化Rb.结果 与青年组及对照组比较,衰老模型组细胞活力下降(P＜0.01),β-半乳糖苷酶活性升高(P＜0.01),CyclinD1 mRNA表达升高(P＜0.01),CDK4 mRNA表达下降(P＜0.01),p16INK4a表达升高(P＜0.01),Rb磷酸化减少(P＜0.01);与衰老模型组细胞比较,中剂量和大剂量GLP细胞活力明显提高(均P＜0.01),而β-半乳糖苷酶活性降低(均P＜0.01),CyclinD1 mRNA表达降低(均P＜0.01),CDK4 mRNA表达升高(均P＜0.01),p16INK4a表达降低,Rb磷酸化增多(均P＜0.01),但两组之间差异无统计学意义(均P＞0.05).结论 GLP可通过改变细胞周期调控因子CyclinD1/CDK4/p16INK4a进而调节Rb的磷酸化状态,发挥抗H2O2诱导的HDF细胞衰老作用.     

Valsartan延缓血管内皮细胞衰老及p16INK4a表达变化的研究

目的 探讨Valsartan对血管内皮细胞衰老与p16INK4a表达变化的影响,为寻求廷缓内皮细胞衰老途径提供理论和实验依据.方法 体外培养人脐静脉内皮细胞,子血管紧张素Ⅱ及Valsartan干预,实验分为空白对照组、血管紧张素Ⅱ诱导组及Valsartan组,采用β-半乳糖苷酶(β-gal)染色鉴定细胞衰老;流式细胞术分析细胞周期变化;免疫细胞化学染色法、Western blot分析各组细胞p16INK4a蛋白的表达.结果 与对照组比较,血管紧张素Ⅱ诱导组β-半乳糖苷酶阳性染色率显著增多81.24％±6.46％,细胞周期停滞于G0-G1(88.36％±6.45％),p16INK4a 蛋白表达水平上调(P＜0.05);予以Valsartan干预后,β-半乳糖苷酶阳性细胞染色率减少,G0-G1细胞减少,p16INK4a蛋白表达水平下调(P＜0.05).结论 血管内皮细胞衰老分子机制可能通过下调p16INK4a的表达,使细胞周期停滞于G1期有关,Valsartan对血管内皮细胞衰老有一定保护作用,可能通过调控p16INK4a的表达发挥其延缓3血管内皮细胞衰老的作用.     

AngⅡ诱导血管内皮细胞衰老相关基因表达的研究

目的 探讨血管紧张索Ⅱ(AngⅡ)诱导人脐静脉内皮细胞(HUVECs)衰老相关基因p16INK4a、p21cip1的表达.方法 体外培养HU-VECs并予AngⅡ(10-6mol/L)干预,采用光镜观察细胞形态学改变,β-半乳糖苷酶(β-gal)染色和流式细胞术鉴定细胞衰老,并利用免疫细胞化学染色法分析Ang Ⅱ诱导HUVECs 0、12、24、36、48 h的p16INK4a阳性细胞表达率,Western印迹法分析AngⅡ诱导HUVECs 0、12、24、36、48 h的p16INK4a、p21cip1蛋白表达的时间效应关系.结果 AngⅡ诱导组HUVECs出现典型的细胞体积增大,形态不规则;约80%的细胞呈现β-gal阳性染色(80.10±6.81)%,流式细胞仪检测细胞周期停滞于G0/G1(91.36±6.45)%,证实细胞衰老;AngⅡ呈时间依赖性上调p16IK4a、p21cip1蛋白表达.结论 AngⅡ诱导血管内皮细胞衰老的分子机制之一可能与上调衰老细胞内细胞周期蛋白p16INK4a、p21cip1的表达,使细胞周期停滞于G1期有关.     

N-乙酰半胱氨酸通过调控细胞周期蛋白加重乳鼠心肌细胞的衰老

目的 了解N-乙酰半胱氨酸(NAC)对心肌细胞衰老的影响及其机制.方法 将培养的SD乳鼠心肌细胞随机分为1 d组、5 d组、10 d组、1 d+NAC(1 mmol/L)组、5 d+NAC(1 mmol/L)组、10 d+NAC(1 mmol/L)组.采用流式细胞仪检测细胞周期.采用实时定量PCR与Western blot等方法检测p16INK4a、p21WAF1及Rb基因mRNA与蛋白水平表达的变化.采用β-半乳糖苷酶原位染色试剂盒检测β-半乳糖苷酶活性的改变.结果 5 d+NAC(1 mmol/L)组、10 d+NAC(1 mmol/L)组G0/G1期细胞数分别为86.71％、91.23％,显著高于单纯5 d组、10 d组的82.13％、87.97％,P均＜0.01.5 d+NAC(1 mmol/L)组、10 d+NAC(1 mmol/L)组p16INK4a基因mRNA拷贝数与β-actin比值分别为0.48、1.31,显著高于单纯5 d组、10 d组的0.35、0.74,P＜0.05与＜0.01.p16INK4a基因蛋白表达与B-actin比值分别为0.96、1.12,显著高于单纯5 d组、10 d组的0.31、0.49,P均＜0.01.5 d+NAC(1 mmol/L)组、10 d+NAC(1 mmol/L)组p21WAF1基因mRNA拷贝数与β-actin比值分别为1.25、2.13,显著高于单纯5 d组、10 d组的0.96、1.24,P＜0.05与＜0.01.p21WAF1基因蛋白表达与β-actin比值分别为1.22、2.16,显著高于单纯5 d组、10 d组的0.71、1.13,P均＜0.01.5 d+NAC(1 mmol/L)组、10 d+NAC(1 mmol/L)组Rb基因mRNA拷贝数与β-actin比值分别为0.18、0.09,显著高于单纯5 d组、10 d组的0.35、0.17,P均＜0.01.Rb基因蛋白表达与β-actin比值分别为0.84、0.33,显著低于单纯5 d组、10 d组的1.47、0.81,P＜0.05与＜0.01.5 d+NAC(1 mmol/L)组、10 d+NAC(1 mmol/L)组β-半乳糖苷酶活性分别为29.71％、79.31％,显著高于单纯5 d组、10 d组的17.46％、58.24％,P均＜0.05.结论 NAC可通过增加p16INK4a与p21WAF1基因表达,抑制Rb蛋白的磷酸化,从而促使心肌细胞周期阻滞于G0/G1期,β-半乳糖苷酶活性明显增强,加重细胞衰老.     

菟丝子醇提液对衰老模型大鼠肝细胞p16和cyclinD1基因表达的影响

目的 研究菟丝子醇提液对衰老模型大鼠肝细胞p16和cyclinD1基因表达的影响,探讨菟丝子延缓衰老作用的机制.方法 实验以50只Wistar大鼠为研究对象,采用D-半乳糖法制作衰老模型,采用经胃灌服法按照0.8g·kg-1 ·d-1给药,采用半定量RT-PCR法测定大鼠肝组织p16和cyclinD1 mRNA的表达,免疫组化SABC法检测p16和cyclinD1蛋白的表达,并观察菟丝子醇提液对其影响.结果 衰老模型大鼠p16 mRNA及蛋白表达较青年组明显增高(P＜0.01),而cyclinD1 mRNA及蛋白表达降低(P＜0.05).菟丝子醇提液可降低p16基因表达(P＜0,01),使cyclinD1基因表达增强(P＜0.05),并呈现时间渐进性改变.结论 菟丝子醇提液通过影响细胞调控因子p16、cyclinD1表达延缓肝细胞的衰老.     

健康大鼠血管衰老性重塑与血管衰老相关基因的关系

目的通过研究健康大鼠血管衰老性重塑形态学变化及衰老相关基因表达,探讨血管衰老性重塑可能的分子调控机制,为临床有效干预血管衰老提供分子靶点。方法观察主动脉组织形态及内皮细胞显微结构变化,应用Western blotting分析4、10、16月和24月龄大鼠血管重塑p16INK4a和p21cip1蛋白表达变化。结果随增龄,大鼠主动脉管壁增厚,纤维化程度增高,内皮细胞形态呈现衰老改变,p16INK4a和p21cip1蛋白表达呈时间依赖性上调。结论血管衰老性重塑的分子机制之一可能与上调细胞周期蛋白p16INK4a和p21cip1的表达有关。进一步阐明其调控机制可为延缓血管衰老,防治动脉粥样硬化提供理论依据。     

松花粉抗成纤维细胞复制性衰老的机制

目的 研究松花粉对衰老成纤维单细胞面积、β-半乳糖苷酶染色(SA-β-gal)阳性率、p16INK4A和p21CIP-1表达以及细胞周期的影响.方法 以二倍体成纤维(2BS)细胞建立衰老细胞模型.生物体视学法分析单细胞面积变化;免疫组化法测SA-β-gal阳性率;流式细胞术分析细胞周期;RT-PCR法测定p16INK4A、p21CIP-1基因mRNA表达量.结果 56代细胞出现典型的衰老细胞形态改变,同时SA-β-gal染色阳性率与G1期细胞比例均增高.经松花粉处理后,衰老细胞的单细胞面积、SA-β-gal染色阳性率与G1期细胞比例均显著减少(P＜0.05);p16INK4A与p21CIP-1mRNA的表达量均较衰老模型组明显下调(P＜0.05). 结论松花粉具有改善细胞复制性衰老的作用,其分子机制可能与下调p16INK4A及p21CIP-1基因mRNA的表达从而改善衰老细胞G1期阻滞有关.     

睾酮对亚急性衰老小鼠下丘脑的影响及其机制

目的观察低刘量睾酮对小鼠下丘脑衰老的影响及其可能的调控机制。方法将24只健康雄性C57小鼠随机分为3组:D-半乳糖+睾酮治疗组(治疗组)、D-半乳糖组和正常对照组,每组8只。用药5个月后分离小鼠下丘脑组织,制备石蜡切片,测定小鼠下丘脑衰老相关性β-半乳糖苷酶(SA-β-Gal)染色情况,用免疫组织化学法检测p16~(INK4a)蛋白的表达水平。结果与正常对照组比较,D-半乳糖组小鼠体重降低(P<0.05),下丘脑SA-β-Gal染色阳性细胞率和p16~(INK4a)蛋白阳性细胞率明显升高(P<0.05);与D-半乳糖组比较,治疗组小鼠体重增加(P<0.05).下丘脑SA-β-Gal染色阳性细胞率和p16~(INK4a)蛋白阳性细胞率明显降低(P<0.05)。结论低剂量睾酮可能通过改变p16~(INK4a)的表达而发挥抗下丘脑细胞衰老的作用。     

睾酮对人大网膜脂肪细胞脂联素mRNA表达的影响

目的 探讨睾酮对人大网膜脂肪细胞脂联素mRNA表达的影响.方法 原代培养人大网膜前脂肪细胞,诱导分化为成熟的脂肪细胞,分别对成熟的细胞以0 nmol/L、1 nmol/L、10 nmol/L和100 nmol/L的睾酮处理24 h,及以100 nmol/L的睾酮处理12 h、24 h及48 h,以NAPDH为内参照,用半定量RTPCR法检测不同浓度睾酮培养下人大网膜脂肪细胞脂联素mRNA表达.结果 随着100 nmol/L睾酮处理时间的延长,人大网膜脂肪细胞脂联素mRNA表达逐渐下降(P<0.05).当睾酮浓度由0 nmol/L向100 nmol/L增大时,人大网膜脂肪细胞脂联素mRNA表达逐渐下降(P<0.05).结论 睾酮降低人大网膜脂肪细胞脂联素mRNA表达呈剂量和时间依赖性.     

Liver cell adenoma and liver cell adenomatosis

During the last three decades liver cell adenoma and liver cell adenomatosis have emerged as new clinical entities in hepato-logical practice due to the widespread use of oral contraceptives and increased imaging of the liver. On review of published series there is evidence that 10% of liver cell adenomas progress to hepatocellular carcinoma, diagnosis is best made by open or laparoscopic excision biopsy, and the preferred treatment modality is resection of the liver cell adenoma to prevent bleeding and malignant transformation. In liver cell adenomatosis, the association with oral contraceptive use is not as high as in solitary liver cell adenomas. The risk of malignant transformation is not increased compared with solitary liver cell adenomas. Treatment consists of close monitoring and imaging, resection of superficially located, large (>4 cm) or growing liver cell adenomas. Liver transplantation is the last resort in case of substantive concern about malignant transformation or for large, painful adenomas in liver cell adenomatosis after treatment attempts by liver resection.     

Red cell exchange in sickle cell disease

Red cell exchange transfusion is frequently of use in the management of patients with sickle cell disease either electively or therapeutically. Modern cell separators allow this procedure to be performed rapidly, effectively and safely. These machines have a number of advantages over manual exchange procedures. The patient remains isovolaemic, there is little loss of plasma or platelets, the procedure is relatively short and in elective circumstances can be performed on an outpatient basis. In this series 66 exchanges were performed on 21 patients with an overall increase in HbA of 70%. The COBE Spectra gave a mean increase in HbA of 77%, with the majority of patients achieving an HbA of > 90% post exchange. Automated redcell exchange was well tolerated by most patients, and adverse effects were limited to symptoms of hypocalcaemia which were easily treated, and to transfusion reactions. Cell separators can therefore be recommended for exchange transfusion in patients with sickle cell disease, who require an increase in HbA levels either prophylactically or therapeutically. They are safe, effective, easy and quick to use.     

Erythrocyte-endothelial cell adherence in sickle cell disorders

Detachment of individual sickle erythrocytes from cultured endothelial cell monolayers has been evaluated by a fluid-shearing technique in an effort to quantitate adherence at shear forces that would be anticipated in the in vivo circulation. Nonirreversibly sickled cells (non-ISC) were more adherent at normal oxygen tensions than control cells. More than 1% non-ISC remained attached to the monolayer at forces greater than physiologic shear stresses in capillary and venous circulations, and many of the most avidly attached cells, once separated, immediately reattached to adjacent endothelial cells. These data suggest that hemoglobin S-containing erythrocytes may have a higher frequency of adherence in vivo in regions of low shear stress where prolonged erythrocyte-endothelial cell contact could occur. Some of these cells detached by shear force would subsequently reattach in in vivo conditions. Plasma-enhanced attachment frequency and plasma from blood in a case of sickle crisis caused further increase. These observations further support the concept that sickle erythrocyte- endothelial cell interaction may be a significant factor in initiation of vascular occlusive events in sickle cell disease.     

Actin filament debranching regulates cell polarity during cell migration and asymmetric cell division

The formation of the branched actin networks is essential for cell polarity, but it remains unclear how the debranching activity of actin filaments contributes to this process. Here, we showed that an evolutionarily conserved coronin family protein, the Caenorhabditis elegans POD-1, debranched the Arp2/3-nucleated actin filaments in vitro. By fluorescence live imaging analysis of the endogenous POD-1 protein, we found that POD-1 colocalized with Arp2/3 at the leading edge of the migrating C. elegans neuroblasts. Conditional mutations of POD-1 in neuroblasts caused aberrant actin assembly, disrupted cell polarity, and impaired cell migration. In C. elegans one-cell−stage embryos, POD-1 and Arp2/3, moved together during cell polarity establishment, and inhibition of POD-1 blocked Arp2/3 motility and affected the polarized cortical flow, leading to symmetric segregation of cell fate determinants. Together, these results indicate that F-actin debranching organizes actin network and cell polarity in migrating neuroblasts and asymmetrically dividing embryos.

Cell polarity is a fundamental feature of virtually all eukaryotic cells and plays crucial roles in a wide range of cellular processes, including cell motility, asymmetric cell division, and cell signaling (1). The establishment of cell polarity involves the asymmetric assembly of distinct cellular components to perform specialized functions. The actin-related protein (Arp) 2/3 complex-dependent branched actin networks and the pushing force they produce provide the principal means for cells to remodel the plasma membrane during cellular polarization (2). For example, in the leading edge of a migrating cell, the local Arp2/3-nucleated actin polymerization powers asymmetric projections of the plasma membrane (3). During asymmetric cell division of the Caenorhabditis elegans zygote, an actomyosin flow is central to the transport of the polarity PAR proteins into defined subcellular domains (4).Actin filaments'' continuous assembly must be balanced by actin depolymerization to ensure a constant supply of actin monomers for new growth. The Arp2/3 complex potency in actin nucleation empowers this complex as an essential regulator to organize the actin cytoskeleton. While Arp2/3 by itself is biochemically inactive, interactions with nucleation-promoting factors (NPFs) such as the Wiskott Aldrich syndrome protein (WASP)/WASP family verproline-homologous (WASP/WAVE) family proteins shift the Arp2/3 complex from its open, inactive conformation to a closed, active conformation (5, 6). The conformationally activated Arp2/3 complex then binds to the side of preexisting actin filaments to nucleate a branch from the mother filament (7–12). Conversely, nucleation by Arp2/3 can be inhibited by several binding partners, including glia maturation factor (GMF), Gadkin, Arpin, and Coronin, whose activities replenish available pools of actin monomers and Arp2/3 complexes for sustained actin assembly (13–18).The coronin family proteins are conserved actin regulators (19). The phylogenetic analysis grouped coronin genes into three types (19, 20). The best-characterized coronin is the Type I coronin (e.g., Coronin 1B) that binds to actin filaments through the β-propeller structure and to the Arp2/3 complex via its N terminus. These interactions block the docking of Arp2/3 onto actin filaments or facilitate debranching the existing actin network (20). Coronin 1B simultaneously interacts with the Slingshot phosphatase to dephosphorylate and activate ADF/Cofilin proteins that sever actin filaments, thereby promoting the actin network disassembly (13). Despite significant progress on Type I coronin, the activity and function of other coronins remain unclear. In particular, Type III coronins, known as POD-1 in C. elegans and Drosophila or Coronin7 in Dictyostelium and humans, contain two tandem coronin repeats, making them distinct from other coronins (19–21). POD-1 was biochemically isolated from C. elegans oocytes (22), and its mutations disrupted the polarity and architecture in early C. elegans embryos and impaired midlife touch sensitivity of the nematode (21, 23). However, it remains unclear how the Type III coronin functions. The Drosophila homolog of POD-1 is required for correct axon guidance, and the purified Dpod-1 cross-links the actin and microtubule cytoskeletons (24), whereas the mammalian Coronin7 was implicated in the Golgi morphology and function (25, 26), demonstrating the functional divergence of this family of coronin. Here, we show that the C. elegans POD-1 debranches Arp2/3-nucleated actin filaments in vitro and that POD-1 regulates cell polarity by remodeling the actin cytoskeleton during cell migration and asymmetric cell division.     

Red cell alloimmunization in sickle cell disease

Alloimmunization to red cell antigens contributes to morbidity in transfused patients. It has been recommended that blood for sickle cell patients need not be matched for antigens other than ABO and Rh(D), as there is no greater incidence of antibody production than in other multitransfused patient populations. Post transfusion alloimmunization was studied in a group of 34 sickle cell disease patients attending a U.K. haemoglobinopathy clinic. Red cell antibodies were formed in 17.6% of the transfused patients and Rhesus and Kell antibodies accounted for 66% of this total. In order to reduce alloimmunization, a policy of performing extended red cell phenotyping on the patients, and providing blood matched for Kell, and in certain circumstances the Rhesus antigens other than Rh(D), is recommended.     

Misdiagnosis of clear cell renal cell carcinoma

Clear cell renal cell carcinoma (RCC) represents the most common histological subtype of malignant kidney tumors. Based on symptoms alone, clear cell RCC is indistinguishable from other histological classes of RCC unless the tumor is present in the context of an RCC syndrome. Histopathological examination is, therefore, important to accurately identify clear cell RCC. Clear cell RCCs have characteristic morphological criteria; these tumors can be easily identified upon typical presentation, but diagnosis can be challenging when tumor cell pattern is unusual or when availability of tissue samples is limited. In this Review, the clinical, radiological and pathological characteristics of clear cell RCCs are described, as well as the potential tumors that can be confused with clear cell RCC and need to be considered in the differential diagnoses. Finally, the importance of an accurate diagnosis is highlighted in the context of the increasing use of preoperative tissue sampling and the prevalence of clear cell tumors associated with hereditary syndromes, which could have different therapeutic and prognostic implications for patients and their families.     

Mechanism of red blood cell aging: Relationship of cell density and cell age

The human red cell has a life span of 120 days. The mechanism that determines cell removal from the circulation with such precision remains unknown. Most studies of red cell aging have been based on analysis of cells of progressively increasing age separated by density. The relationship between red cell age and density has been recently challenged, and the hypothesis has been put forward that cell death is not the result of a progressive deterioration of essential cell constituents. This theory was based on preliminary observations in transient erythroblastopenia of childhood, which could not later be confirmed. When the relationship between cell aging and increasing density is critically reviewed, it appears to be based on firm experimental evidence, confirmed by in vivo demonstration of decreasing survival of cells of increasing age. Analysis of studies using buoyant density gradients reveals that this technique can easily distinguish the single exponential slope of decline for those cell components that change progressively throughout the red cell life span from the biphasic decline of those that decrease drastically at the reticulocyte-mature red cell transition. The view that the aging of the red cell and its removal from the circulation result from a progressive series of events during the 120 days of its life span appears to be the most consistent with the available data. Density separation, validated by much experimental evidence, remains a most useful technique for the study of the mechanism of aging of the red cell. © 1993 Wiley-Liss, Inc.     

Sphere-forming cell subpopulations with cancer stem cell properties in human hepatoma cell lines

Background

Cancer stem cells (CSCs) are regarded as the cause of tumor formation and recurrence. The isolation and identification of CSCs could help to develop novel therapeutic strategies specifically targeting CSCs.

Methods

Human hepatoma cell lines were plated in stem cell conditioned culture system allowed for sphere forming. To evaluate the stemness characteristics of spheres, the self-renewal, proliferation, chemoresistance, tumorigenicity of the PLC/PRF/5 sphere-forming cells, and the expression levels of stem cell related proteins in the PLC/PRF/5 sphere-forming cells were assessed, comparing with the parental cells. The stem cell RT-PCR array was performed to further explore the biological properties of liver CSCs.

Results

The PLC/PRF/5, MHCC97H and HepG2 cells could form clonal nonadherent 3-D spheres and be serially passaged. The PLC/PRF/5 sphere-forming cells possessed a key criteria that define CSCs: persistent self-renewal, extensive proliferation, drug resistance, overexpression of liver CSCs related proteins (Oct3/4, OV6, EpCAM, CD133 and CD44). Even 500 sphere-forming cells were able to form tumors in NOD/SCID mice, and the tumor initiating capability was not decreased when spheres were passaged. Besides, downstream proteins DTX1 and Ep300 of the CSL (CBF1 in humans, Suppressor of hairless in Drosophila and LAG1 in C. elegans) -independent Notch signaling pathway were highly expressed in the spheres, and a gamma-secretase inhibitor MRK003 could significantly inhibit the sphere formation ability.

Conclusions

Nonadherent tumor spheres from hepatoma cell lines cultured in stem cell conditioned medium possess liver CSC properties, and the CSL-independent Notch signaling pathway may play a role in liver CSCs.     

Automated red cell exchange in sickle cell disease

We used multiple optical trapping to study the mechanism of red cell (dis)aggregation. Two sets of optical 'tweezers' were used to bring two red blood cells together to form a two-cell aggregate and then to pull them apart, to study the interaction between the cells.
We found that cross-bridging occurred in normal reversible aggregation as we observed binding and the occurrence of small tethers between opposite cell membranes. Furthermore, the cells could only be parted by sliding them side by side with a maximum velocity in the order of μm/s indicating accumulation of the cross-bridges.     

胆红素对肝星状细胞-T6增殖及细胞周期的影响

[目的]观察胆红素对肝星状细胞(HSC)-T6增殖及细胞周期影响.[方法]将培养细胞分成正常组和胆红素不同浓度(10 μmol/L、30 umol/L、50 /μmol/L、70 μmol/L、100 μmol/L)干预组,采用MTT法观察胆红素对HSC-T6增殖的影响,流式细胞仪观察各组细胞周期的变化.[结果]①不同浓度胆红素对HSC-T6均有促进增殖作用,且呈一定的量效关系,与正常组比较差异有统计学意义(P＜0.05);②10 μmol/L、50 μmol/L、100 μmol/L浓度胆红素作用HSC-T6后,G0/G1期减少,S期增加,G2/M期增加,与正常组比较均P＜0.05.[结论]胆红素对HSC-T6均有促进增殖作用.