非小细胞肺癌中WWOX蛋白、Ki67的表达及其意义

目的 探讨WWOX(WW domain-containing oxidoreductase)基因在非小细胞肺癌(NSCLC)组织中的表达及其临床意义.方法 用免疫组化方法检测50例鳞癌,31例腺癌及20例癌旁正常组织中WWOX基因蛋白的表达,并分析其与各临床病理指标、细胞增殖之间的关系.结果 WWOX基因在72.8%的NSCLC中失表达或表达减少,而在相邻正常肺组织中有80.0%正常表达.WWOX基因的表达与组织类型、腺癌细胞分化程度密切相关(r=0.262,r=0.457,P＜0.05),在鳞癌和低分化腺癌中WWOX基因失表达或表达减少.细胞增殖指数越高,WWOX基因表达越少,二者呈负相关(r=-0.252,P＜0.05).Ki67的表达与吸烟、组织分化、临床分期、淋巴结转移密切相关(均P＜0.05);与WWOX蛋白表达呈负相关(r=-0.252,P＜0.05).结论 WWOX蛋白在NSCLC组织中呈低表达,其表达的缺失可能在不同类型NSCLC的形成中发挥了不同的作用,而且与肿瘤的恶性程度及侵袭有关.Ki67蛋白的高表达提示预后不佳.     

STAT5和WWOX在非小细胞肺癌中的表达及相关性研究

目的 探讨信号转导和转录激活因子5(STAT5)和WW结构域氧化还原酶(WWOX)在非小细胞肺癌(NSCLC)中的表达及相关性研究.方法 用免疫组化SP法检测40例手术切除的NSCLC组织和20例正常肺组织中STAT5和WWOX的蛋白表达.结果 STAT5蛋白在NSCLC中的表达明显高于正常肺组织,而WWOX在NSCLC中的表达明显低于正常肺组织(P<0.01);STAT5表达水平与NSCLC组织学类型有关,在腺癌组织中的表达明显高于鳞癌(P<0.01),WWOX的表达与淋巴结转移相关,有淋巴结转移的表达低于无淋巴结结转移(P<0.01);STAT5蛋白和WWOX蛋白在NSCLC组织中的表达呈负相关(P<0.05).结论 在NSCLC中存在STAT5的过度表达以及WWOX的失表达,STAT5表达水平与NSCLC组织学类型有关,而WWOX的表达与淋巴结转移相关.提示在NSCLC的发生机制中,WWOX可能通过抑制STAT5系统,促进细胞凋亡,起到抑癌作用.     

支气管肺癌组织中包含氧化还原酶的WW域还原蛋白、同源性磷酸酶-张力蛋白的表达及临床意义

目的探讨包含氧化还原酶的WW域抗原(WWOX)蛋白与同源性磷酸酶-张力蛋白(PTEN)在支气管肺癌组织中的表达及临床意义。方法应用免疫组化法检测WWOX与PTEN蛋白在87例支气管肺癌组织标本与23例正常肺组织标本中的表达,分析WWOX与PTEN蛋白表达与支气管肺癌患者临床病理特征之间的关系,并探讨两者在支气管肺癌组织中的表达相关性。结果 WWOX与PTEN蛋白在支气管肺癌组织中的的阳性表达均显著低于正常组织中的表达(χ2=14.810,P0.001;χ2=17.363,P0.001)。WWOX蛋白表达与患者的性别、癌组织分化程度、临床分期、是否发生淋巴结转移均有关(P0.05),但与年龄、肿瘤大小无关(P0.05);而PTEN蛋白则只与是否发生淋巴结转移有关(P0.05),与其他临床病理参数均无关(P0.05)。WWOX与PTEN蛋白的表达之间不存在关联性(χ2=2.098,P=0.147)。结论 WWOX与PTEN蛋白可能都参与了支气管肺癌的发生与恶性发展,但两者是通过不同的途径发生作用。     

非小细胞肺癌中WWOX蛋白的表达及意义

目的 研究抑癌基因WWOX在非小细胞肺癌中的蛋白表达及临床意义.方法 应用免疫组织化学二步法检测40例非小细胞肺癌石蜡标本及21例癌旁正常肺组织中WWOX蛋白的表达.结果 ①癌旁正常肺组织中WWOX蛋白阳性表达率高于非小细胞肺癌组织(85.71％ vs 37.50％,P＜0.05),鳞癌中WWOX蛋白阳性表达率与腺癌差异无统计学意义(34.62％ vs 42.86％,P＞0.05);②男性非小细胞肺癌患者癌组织中WWOX蛋白阳性表达率低于女性非小细胞肺癌患者(25.00％ vs56.25％,P＜0.05),吸烟指数≥400的患者癌组织中WWOX蛋白阳性表达率低于吸烟指数＜400的患 者(19.05％ vs 57.89％,P＜0.05),而WWOX蛋白呈阳性表达的患者年龄与阴性表达者之间差异无统计学意义(P＞0.05);③分化不良的非小细胞肺癌组织中WWOX蛋白阳性表达率与中等分化和分化良好者相近(P＞0.05);④Ⅰ+Ⅱ期非小细胞肺癌患者癌组织中WWOX蛋白阳性表达率与Ⅲ+Ⅳ期患者相比差异无统计学意义(P＞0.05),转移病例的非小细胞肺癌组织中WWOX蛋白阳性表达率与无转移病例相近(P＞0.05).结论 WWOX蛋白在非小细胞肺癌组织中表达较癌旁正常肺组织降低,且与患者性别及吸烟指数密切相关,而与年龄、病理类型、组织分化程度、临床分期以及有无转移无明显关系.     

非小细胞肺癌组织及癌旁组织VEGF、P16蛋白的表达及意义

目的分析P16蛋白、血管内皮生长因子(VEGF)在非小细胞肺癌(NSCLC)组织及癌旁组织的表达情况。方法应用免疫组化SP法检测NSCLC组织65例,距肿瘤边缘5 cm以上癌旁正常组织20例中VEGF、P16蛋白的表达。结果①VEGF在肺癌组织的阳性表达率72.3%,明显高于癌旁组织的阳性表达率35.0%(P<0.05);P16蛋白在肺癌组织的阳性表达率47.7%,明显低于癌旁组织的阳性表达率85.0%(P<0.05)。②P16蛋白的表达与肺癌淋巴结转移、临床分期、分化程度有关,而与病理类型无关;VEGF的表达与临床分析、淋巴结转移有关。NSCLC组织中P16蛋白与VEGF之间呈负相关(rs=-0.537,P<0.01)。结论 NSCLC组织中存在VEGF与P16蛋白表达的异常,且两者表达呈负相关,推测NSCLC的发病与血管生成及P16表达异常有关。     

Twist蛋白在非小细胞肺癌中的表达水平及其与VEGF的关系

目的 探讨转录调节因子Twist在非小细胞肺癌(NSCLC)中的表达水平及其与血管内皮生长因子(VEGF)关系.方法 采用链霉素抗生物素蛋白-过氧化物酶(SP)免疫组织化学方法检测50例NSCLC及15例癌旁正常肺组织中Twist蛋白、VEGF的表达,并分析两者与临床病理特征的关系.结果 NSCLC组织中Twist阳性率44%,明显高于癌旁正常肺组织,其表达与肿瘤分化程度有关.VEGF在肺癌、癌旁正常肺组织中的阳性率分别为50%和26.67% (P ＜0.05),其表达与肿瘤分化程度、TNM分期及淋巴结转移有关.Twist蛋白与VEGF的表达之间存在显著正相关(r=0.560 2,P＜0.01).结论 在NSCLC中Twist蛋白、VEGF表达明显增高,其表达与肿瘤分化、分期有关.NSCLC组织中Twist与VEGF表达的上调对肿瘤的发生、发展起着重要作用.     

非小细胞肺癌中FADD蛋白的表达及与细胞凋亡蛋白P53的关系

目的探讨非小细胞肺癌(NSCLC)中Fas相关死亡域蛋白(FADD)的表达及与细胞凋亡蛋白P53关系。方法采用免疫组化方法分别检测61例肺癌组织和30例癌旁正常组织中的FADD和P53表达,然后进行比较。结果 61例肺癌组织中FADD蛋白阳性率为88.52%,30例癌旁正常组织中FADD蛋白阳性率96.67%,两者比较差异无统计学意义(P>0.05);而61例肺癌组织中P53蛋白阳性率为75.41%,明显高于30例癌旁组织(0.00%),差异具有统计学意义(P<0.01)。在61例肺癌组织中FADD蛋白与P53蛋白表达具有较好的相关性(χ2=12.56,P<0.01)。在NSCLC中FADD蛋白及P53蛋白的表达与患者的年龄、性别、吸烟史、临床分型、病理类型、淋巴结转移、肿瘤直径等指标无明显的关系(P>0.05),而与NSCLC的分化程度、TNM分期有关(P<0.01)。结论 FADD蛋白与P53蛋白在NSCLC中表达具有良好的一致性,检测手术后肺癌组织的FADD和P53蛋白表达水平,可作为评估NSCLC预后情况的手段之一。     

非小细胞肺癌组织中凋亡抑制蛋白Livin的表达及意义

目的 研究肺癌相关Livin基因在非小细胞肺癌(NSCLC)组织中的表达以及与p53基因的关系.方法 采用RT-PCR方法检测48例NSCLC组织Livinα mRNA的表达,用免疫组化SABC法检测livin和p53蛋白在48例NSCLC患者肺癌组织切片中的表达.结果 48例NSCLC中15例检测到Livinα mRNA表达,其阳性表达率为31.3%,而正常肺组织和癌旁及良性疾病肺组织均未检测到Livinα mRNA表达.Livin蛋白在腺癌、低分化癌、有淋巴结转移者中的表达阳性率明显高于鳞癌和大细胞癌、高中分化癌和无淋巴结转移者(P＜0.01),而癌旁组织和良性疾病肺组织未检出阳性表达.Livinα mRNA表达与p53呈正相关(r=0.457,P＜0.01);livin蛋白表达与p53呈正相关(r=0.563,P＜0.01).结论 Livin在NSCLC组织中高表达,可能成为肺癌诱导凋亡治疗的新靶点.     

BCAR1和Smad3蛋白在非小细胞肺癌组织中的表达及临床病理意义

目的 探讨乳腺癌抗雌激素耐药蛋白(BCAR1)和Smad3蛋白在非小细胞肺癌(NSCLC)发生发展中的作用.方法 收集NSCLC患者术后肿瘤标本150例及正常肺组织标本60例,应用免疫组化法检测BCAR1和Smad3蛋白的表达状况,分析二者的相关性以及与临床病理特征和预后的关系.结果 BCAR1蛋白在NSCLC中表达的阳性率(86.0％)高于正常肺组织(13.3％)、Smad3蛋白在NSCLC中表达的阳性率(17.3％)低于正常肺组织(68.3％) (P ＜0.0001).BCAR1蛋白高表达与NSCLC低分化、高临床分期以及预后差相关(P =0.004,P=0.008,P=0.022);Smad3蛋白低表达与NSCLC胸膜侵犯、高临床分期以及预后差相关(P=0.02,P =0.008,P=0.002).BCAR1和Smad3蛋白的表达呈负相关(r=-0.830,P ＜0.000 1).结论 BCAR1和Smad3参与NSCLC发生发展过程,联合检测BCAR1和Smad3蛋白可能有助于NSCLC的诊断和预后评估.     

非小细胞肺癌组织中AKT1、PDCD4蛋白表达变化及意义

目的观察非小细胞肺癌(NSCLC)组织中丝/苏氨酸蛋白激酶1(AKT1)和程序性细胞死亡因子4(PDCD4)蛋白表达变化,并探讨其临床意义。方法收集65例NSCLC患者的手术切除肿瘤组织为NSCLC组,30例受检者的正常肺泡组织为肺泡对照组,30例受检者的正常支气管断端组织为支气管对照组。用免疫组化法检测三组标本中的AKT1、PDCD4,并分析NSCLC组二者表达与肿瘤临床病理参数的关系。结果与支气管对照组和肺泡对照组相比,NSCLC组AKT1表达升高,PDCD4表达降低,P均<0.05。NSCLC组AKT1表达与NSCLC分化程度、淋巴结转移及TNM分期有关(P均<0.05),与患者的性别、年龄和肿瘤的大小、组织学类型无关;NSCLC组中PDCD4表达与NSCLC组织学类型有关(P<0.05),与患者的性别、年龄和肿瘤的大小、分化程度、淋巴结转移及TNM分期无关;AKT1和PDCD4在肺腺癌组织中表达呈负相关(r=-0.436,P=0.021),在肺鳞癌组织中无关(r=-0.012,P=0.931)。结论 NSCLC组织中AKT1表达升高、PDCD4表达降低,联合检测两者有助于NSCLC的诊治和预后判断。     

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.     

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 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.     

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.     

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.     

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.     

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.     

Red cell rheology in stomatocyte-echinocyte transformation: roles of cell geometry and cell shape

The influence of the shape of the red blood cell during stomatocyte- echinocyte transformation on its deformability was studied by microsieving through pores with diameters of 2.6, 4.5, and 6.9 micron. A stomatocytic transformation was produced by chlorpromazine (0.02, 0.1, and 0.5 mmol/L) and an echinocytic transformation by sodium salicylate (7.5, 30, and 120 mmol/L). For spherostomatocytes, an increase in filtration resistance through 2.6 and 4.5 micron pores was observed, whereas for spheroechinocytes, a decrease in filtration resistance through 2.6 micron pores was found. Larger pores (6.9 micron) were not sensitive to those shape changes. The changes in deformability can be explained by the fact that the surface area of (sphero)-stomatocytes decreased, whereas that of (sphero)-echinocytes increased; the cell volume remained essentially constant. Echinocytes produced by 24-hour adenosine triphosphate depletion differed from drug- induced echinocytes: they had an increased cell volume at constant surface area and consequently an increased filtration resistance through 2.6- and 4.5-micron filter pores. Shape changes with spicule formation are therefore not a homogeneous entity, and cell geometric factors (eg, surface area and volume) must be assessed with care. The viscosity of red cell suspensions at a hematocrit level of 45% was higher for drug-induced echinocytes than discocytes or stomatocytes at all shear rates tested. We conclude that the normal discocyte represents an optimum shape for the flow in vivo since a stomatocytic transformation could impair the passage through the microcirculation (decrease in cell filterability) and an echinocytic transformation could impair the flow in larger vessels (increase in blood viscosity).     

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.