利用母体血浆游离胎儿DNA进行胎儿SRY基因定量检测

目的探讨胎儿游离DNA在无创性产前诊断中的应用价值。方法行产前诊断的孕妇87例,分为中期妊娠(16～24周)61例(中孕组)和早期妊娠(11～14周)26例(早孕组),采用实时荧光定量PCR方法,利用Taqman探针对妊娠早、中期孕妇血浆游离的胎儿Y染色体性别决定基因(sex-determining region of Y-chromosome,SRY)进行扩增和定量分析。结果孕13周后的样本均得到特异性扩增,特异度和灵敏度均为100%;中孕组男性胎儿SRY检测的平均DNA浓度为155.46copies/mL血浆,实测范围为43.6～326.8copies/mL血浆;早孕组平均浓度为26.42copies/mL血浆,实测范围为14.3～73.3copies/mL血浆。结论采用荧光实时定量PCR在妊娠早、中期可稳定检测到胎儿游离DNA,可作为孕期性连锁遗传性疾病研究或产前诊断的有效补充手段。     

造血干细胞向淋巴系祖细胞增殖HOXB4基因的表达

背景:HOXB4基因不仅能促进造血干细胞的扩增及其功能的活化与表达,而且体内试验表明它不会诱发白血病.因此更好地研究HOXB4在造血细胞增殖分化中的变化及作用对进一步研究造血干细胞的扩增可以提供更多的理论基础.目的:观察人类脐血造血干细胞向淋巴系祖细胞增殖分化过程中HOXB4基因表达的情况及全反式维甲酸对HOXB4基因表达的影响.方法:将培养的淋巴系造血祖细胞按干预方式不同分为2组,全反式维甲酸组:在培养体系中加入全反式维甲酸,终浓度6×10-8mol/L.正常组:不加全反式维甲酸,代之以等量的1640培养液.观察人类脐血造血干细胞经植物血凝素诱导后,在培养第3,7,12天的淋巴细胞集落形成单位生成情况.采用实时荧光定量PCR技术检测脐血造血干细胞向淋巴系祖细胞增殖分化过程中HOXB4基因的表达水平.结果与结论:人脐血造血干细胞向淋巴系祖细胞增殖分化过程中,HOXB4基因晕规律的表达.随培养时间推移,正常组和全反式维甲酸组HOXB4基因的表达均逐渐降低.与正常组比较,全反式维甲酸可上调HOXB4基因的表达.     

Local chromatin interactions contribute to expression of the fibrinogen gene cluster

Essentials

• The fibrinogen gene cluster is flanked by CCCTC‐binding factor (CTCF) interaction sites.
• Chromatin looping of the fibrinogen cluster was demonstrated by chromosome conformation capture.
• Deleting a CTCF interaction site alters chromatin looping and halves fibrinogen expression.
• Looping of the human fibrinogen locus is functionally linked to fibrinogen gene expression.

Summary

Background

The coordinately regulated genes encoding human fibrinogen are clustered. This evolutionarily conserved configuration provides a possible mechanism for co‐regulation whereby regulatory elements influence gene expression locally. The cluster is flanked by CCCTC‐binding factor (CTCF) interaction sites that are candidate insulator regions mediating chromatin looping.

Objectives

To further our understanding of fibrinogen gene regulation, we aimed to investigate whether interactions exist between parts of the fibrinogen locus and how these contacts contribute to fibrinogen expression.

Methods

We used chromosome conformation capture in cultured cell lines to detect chromatin interactions at the fibrinogen gene cluster. We generated clonal cell lines where two CTCF interaction sites at one end of the locus were deleted using CRISPR‐Cas9‐mediated genome editing. Fibrinogen expression and protein production were measured using qRT‐PCR and ELISA, respectively.

Results

We detected proximity between the ends of the fibrinogen locus, regardless of whether cells express fibrinogen. An interaction between the FGA promoter and the edge of the locus was more frequent in fibrinogen‐expressing cells. Deletion of a CTCF site at one edge of the cluster altered chromatin interactions, reduced steady‐state expression of FGB and FGG mRNA, and led to a halving of secreted fibrinogen. These phenotypes were completely restored by reintroduction of the CTCF interaction motif in previously motif‐deleted clones.

Conclusions

Chromatin interactions are important for the coordinated regulation of the human fibrinogen genes. This finding furthers our comprehension of how fibrinogen is produced and identifies a possible source of variability in plasma fibrinogen levels seen in populations.

     

Use of the hereditary persistence of fetal hemoglobin 2 enhancer to increase the expression of oncoretrovirus vectors for human gamma-globin

The development of oncoretrovirus vectors for human gamma-globin has been hampered by problems of low expression and gene silencing. In order to address these problems, we investigated an enhancer element identified from individuals with deletional hereditary persistence of fetal hemoglobin 2 (HPFH2), a genetic condition characterized by elevated levels of gamma-globin in adults. Plasmid transfection studies in erythroid MEL (murine erythroleukemia) cells demonstrated the HPFH2 element could function synergistically with the beta-globin locus control region to enhance the expression of an Agamma-globin gene with a truncated -382 bp promoter. A series of oncoretrovirus vectors were subsequently generated that contain an expression cassette for Agamma-globin linked to various combinations of the HPFH2 enhancer, the alpha-globin HS40 enhancer, and several versions of the promoter from Agamma-globin or beta-globin. Expression analysis in transduced MEL cell clones revealed very high levels of promoter-autonomous silencing that was at least partially abrogated by the HPFH2 enhancer. The vector containing a combination of a -201 bp Agamma-globin gene promoter with the Greek HPFH -117 point mutation and both the HPFH2 and HS40 enhancers exhibited no signs of vector silencing and was expressed at 248+/-99% per copy of mouse alpha-globin (62% of total alpha-globin). This represents a significant improvement over previously reported oncoretrovirus vectors for Agamma-globin, and demonstrates the capacity of the HPFH2 enhancer to abrogate sequence-autonomous silencing of the Agamma-globin promoter in the context of a gene transfer vector.     

Factors that contribute to complications during intrahospital transport of the critically ill.

Transporting patients from the protective environment of the intensive care (ICU) unit to other areas of the hospital has become increasingly common since high technologic testing has become an integral part of health care assessment. The hazards of moving critically ill patients by ambulance or air transport are well recognized and standards of care have been developed based on delineation of these risks. Despite the existing evidence of hazards of interhospital hospital transport, less attention has been given to the potential hazards associated with the intrahospital transport of critically ill patients. A high incidence of serious hemodynamic or respiratory alteration is associated with the intrahospital transport of critically ill patients. In one third of critically ill intrahospital transports, technical mishaps (eg, i.v. disconnects, which could potentially lead to deleterious physiologic outcomes) may occur. As patient acuity increases, there is a greater risk of hemodynamic instability. The purpose of this study was to further investigate the patient complications during transportation to and from the ICU to a diagnostic or treatment site. The sample consisted of thirty-five critically ill patients from the Neuro/Trauma ICU who required continuous physiological monitoring and had an arterial catheter in place. The systemic blood pressure, heart rate and peripheral oxygen saturation were monitored at nine time points throughout the transport process. The incidence of defined technical mishaps that occurred when the patient was off the unit were also recorded. Transport factors examined included the length of time spent off the unit and the number and level of personnel accompanying the patient. A within-subject repeat measure design was used to examine the physiologic changes and mishaps that occurred. Results indicate that while the majority of patients experienced some physiologic responses as a result of transport, the responses were not of sufficient magnitude to be classified as a deleterious. Twenty-three technical mishaps, which included inadvertent ventilator and electrocardiogram disconnects, power failures, interruption of medication administration and disconnection of drainage devices were observed. Factors related to these occurrences of technical mishaps were the number of intravenous solutions and infusion pumps and the time spent outside of the ICU environment.     

Non-invasive prenatal diagnosis of fetal aneuploidies using massively parallel sequencing-by-ligation and evidence that cell-free fetal DNA in the maternal plasma originates from cytotrophoblastic cells

Blood plasma of pregnant women contains circulating cell-free fetal DNA (ccffDNA), originating from the placenta. The use of this DNA for non-invasive detection of fetal aneuploidies using massively parallel sequencing (MPS)-by-synthesis has been proven previously. Sequence performance may, however, depend on the MPS platform and therefore we have explored the possibility for multiplex MPS-by-ligation, using the Applied Biosystems SOLiD(?) 4 system. DNA isolated from plasma samples from 52 pregnant women, carrying normal or aneuploid fetuses, was sequenced in multiplex runs of 4, 8 or 16 samples simultaneously. The sequence reads were mapped to the human reference genome and quantified according to their genomic location. In case of a fetal aneuploidy, the number of reads of the aberrant chromosome is expected to be higher or lower than in normal reference samples. To statistically determine this, Z-scores per chromosome were calculated as described previously, with thresholds for aneuploidies set at > +3.0 and < -3.0 for chromosomal over- or underrepresentation, respectively. All samples from fetal aneuploidies yielded Z-scores outside the thresholds for the aberrant chromosomes, with no false negative or positive results. Full-blown fetal aneuploidies can thus be reliably detected in maternal plasma using a multiplex MPS-by-ligation approach. Furthermore, the results obtained with a sample from a pregnancy with 45,X in the cytotrophoblastic cell layer and 46,XX in the mesenchymal core cells show that ccffDNA originates from the cytotrophoblastic cell layer. Discrepancies between the genetic constitution of this cell layer and the fetus itself are well known, and therefore, care should be taken when translating results to the fetus itself.     

Fetal echocardiography: factors that influence imaging of the fetal heart during the second trimester of pregnancy

The four-chamber view of the heart is an important component of the ultrasonographic examination of the fetus. However, during the second trimester of pregnancy the fetal heart cannot always be imaged in every patient. The purpose of this study was to ascertain the rate of successful imaging of the fetal heart during the second trimester and to determine factors that may influence imaging. Seven hundred and nine second trimester fetuses were examined and an attempt was made to obtain the four-chamber and outflow tract views of the heart. Analysis included multiple logistic regression models of the main effects and interactions of ten candidate variables. The four chambers and outflow tracts were imaged in 643 fetuses (90.7%) and not imaged in 66 (9.3%). Fifty-two of 709 patients (7.3%) had had previous surgery. In the 52 patients with a history of previous surgery, the heart could not be imaged in 18 (34%). Six hundred and fifty-seven patients (92.7%) did not have previous surgery. Of this group, the fetal heart could not be imaged in 48 (7.3%). In only one fetus in which the heart could not be imaged was it because of fetal position. Three independent risk factors that influenced imaging of the fetal heart were gestational age, maternal adipose tissue thickness, and previous lower abdominal surgery. Increasing gestational age increased the probability of imaging the heart, whereas increasing adipose tissue thickness and a history of previous surgery decreased the probability of imaging the heart. When the fetal heart cannot be imaged during the second trimester, these factors should be identified. Using data from this study, the gestational age at which the highest probability of imaging the heart can be determined if the thickness of the adipose tissue and a history of lower abdominal surgery are known.     

Purification and characterization of fetal hematopoietic cells that express the common acute lymphoblastic leukemia antigen (CALLA)

Fetal hematopoietic cells that express the common acute lymphoblastic leukemia antigen (CALLA) were purified from both fetal liver and fetal bone marrow by immune rosetting with sheep erythrocytes coated with rabbit anti-mouse immunoglobulin and by fluorescence-activated cell sorting. Dual fluorescence techniques disclosed that these cells were heterogenous with respect to the expression of a series of differentiation and activation antigens defined by monoclonal antibodies. Thus, whereas all CALLA+ cells were Ia+ and expressed two activation antigens, J2 and T10, only 30-50% expressed B1 antigen. Furthermore, using methanol-fixed cells, it could be shown that approximately 20% contained intracytoplasmic mu chains (cyto-mu) and that approximately 15% were positive for the terminal transferase enzyme (TdT) marker. The CALLA+ fetal cells thus closely resemble the childhood acute lymphoblastic leukemia cell with respect to surface marker phenotype. A population of CALLA- cells devoid of mature erythroid and myeloid surface markers was found to contain higher numbers of TdT+ cells but lower numbers of cyto-mu, B1, and Ia+ cells than the CALLA+ subset. In vitro analysis of normal, purified CALLA+ cells demonstrated that incubation at 37 degrees C with J5 monoclonal antibody specific for CALLA resulted in the specific modulation of surface antigen. Similar results have previously been obtained with CALLA+ tumor cells. Although phenotypic analysis of CALLA+ cells suggests that these cells are relatively immature lymphoid cells, CALLA+ cells do not appear to contain either myeloid precursor cells (CFU-G/M) or the earliest lymphoid stem cells.     

Kinetics of fetal cellular and cell-free DNA in the maternal circulation during and after pregnancy: implications for noninvasive prenatal diagnosis

BACKGROUND: Fetal genetic material is detectable in the maternal circulation and has been used for noninvasive prenatal diagnosis. However, few data are available concerning its quantity and natural history during gestation. STUDY DESIGN AND METHODS: This study prospectively characterized the kinetics of cellular and cell-free fetal DNA in the circulation of 25 healthy women during and after uncomplicated pregnancy. Real-time kinetic PCR was used to quantitate human Y-chromosome sequences, and liquid oligomer hybridization with (32)P-labeled probes was used to verify the identity of amplified products. RESULTS: In all male pregnancies, but no female pregnancies, low-level fetal Y-chromosome DNA was detected in both cellular and cell-free compartments beginning at 7 to 16 weeks but increasing steadily after 24 weeks and reaching a peak at parturition. The fetal DNA decreased rapidly after birth. CONCLUSION: Fetal genetic material can be detected throughout pregnancy, and its quantity is a function of gestational age and of whether the plasma or cellular compartment is examined. Both the absolute quantity of fetal DNA and its ratio to total DNA (maternal + fetal) are greater in the plasma than in the cellular compartment. Fetal DNA is cleared rapidly from both compartments after parturition, which suggests that turnover is dynamic. Because they provide prospective and quantitative data concerning fetal DNA levels, these observations and kinetic PCR methods may have implications for noninvasive prenatal diagnosis. Further studies will be needed to determine the immunologic implications of fetal-maternal DNA exchange and cellular microchimerism.     

B超扫描检查对人中孕胎儿大脑皮质神经胶质细胞超微结构的影响

目的：探讨超声波扫描是否对人中孕胎儿大脑皮质神经胶质细胞超微结构造成影响。方法：将10例因避孕失败而自愿要求引产的单胎中孕妊娠的健康妇女随机分成2组,各5例,均行水囊引产术。第1组为对照组,引产前不作B超扫描;另1组在引产前30min B超经孕妇腹部定点扫描胎儿大脑颞叶皮质10min。引产术后胎儿娩出即取大脑颞叶皮质作透射电镜标本的常规制备与观察。结果：与对照组相比,B超定点扫描检查10min后的胎儿大脑皮质神经胶质细胞的主要变化有：(1)细胞膜不完整;(2)胞质内的亚细胞结构如线粒体、高尔基复合体、粗面内质网等结构不清晰;(3)核周腔增大、变宽;(4)细胞核内的染色体浓缩形成不同形状和大小的块状,呈现明显凋亡征象。结论：B超定点扫描检查10min,胎儿大脑皮质胶质细胞出现明显的细胞凋亡征象。     

Nucleated cells circulating in the peripheral blood contribute to the repair of osteochondral defects only in the early phase of healing

The role of cells circulating in the peripheral blood to participate in the natural repair process of osteochondral defects was evaluated in a green fluorescent protein (GFP) transgenic and wild rat parabiosis model. Two weeks after the parabiosis operation, vascular communication between the conjoined rats was confirmed by flow‐cytometry analysis. A 1.5 mm diameter and 1.0 mm depth osteochondral defect was made in the patellar groove of each rat femoral bone. Histological examination was performed at 1, 2, 4 and 24 weeks following surgery. In the early postoperative phase (1–4 weeks) there were GFP‐negative and ‐positive cells in the defects of both parabiotic rats. GFP‐positive chondrocytes were confirmed partly in the repair tissue of the wild parabiotic rat. In the late postoperative phase (24 weeks), the repaired defects were occupied by cells originating from the adjacent tissue and not from the peripheral blood. The ratio of cells originating from the peripheral blood was approximately 30–40% in the repair tissue at 1 week after surgery, reduced to 0–7% at 24 weeks. From these results it is confirmed that cells circulating in the peripheral blood contributed to the repair of the osteochondral defects, particularly in the early phase of healing. Thus, peripheral blood not only supplies the factors needed for repair but also provides a cell population involved in the wound‐healing process. Copyright © 2012 John Wiley & Sons, Ltd.     

多药耐药基因导入骨髓造血细胞的研究与临床应用

多药耐药基因导入骨髓造血细胞的研究与临床应用孟月生陈学良综述张茂宏审校１多药耐药基因导入骨髓造血细胞的临床意义多药耐药基因的异常扩增和过度表达是肿瘤细胞产生多药耐药性（ＭＤＲ）的重要原因之一。多药耐药基因在人类包括ｍｄｒ１和ｍｄｒ２～３两种，在小鼠包...     

低氧对胚胎肝间质细胞低氧诱导因子1α基因表达的影响

目的:观察低氧培养条件下小鼠胎肝间质细胞中低氧诱导因子1α(hypoxiainduciblefactor1,HIF-1α)的表达情况,了解造血间质细胞在低氧环境中的生物学特性。方法:取孕14.5d小鼠胚胎肝细胞进行贴壁培养及传代。生长至次融合状态的第5代细胞在950mL/LN2和50mL/LCO2混合气条件下培养,持续通以缺氧混合气0(对照组),2,4,8,16,32h,在37℃培养。在合适时间下应用半定量RT-PCR和Westernblot技术检测其HIF-1α基因表达。结果:在常氧压下培养的胎肝间质细胞中,HIF-1αmRNA及其蛋白水平均较低;而低氧培养则可显著提高胎肝间质细胞HIF-1α基因的mRNA及其蛋白水平。HIF-1αmRNA在低氧培养2h时即显著增高,8h时达到高峰水平,PCR产物HIF-1与β-actin信号比从对照组(3.85±1.98)%增加到(60.28±13.48)%,差异有显著性意义(P<0.01);HIF-1α蛋白在低氧培养4h时显著增高,16h时达到高峰水平,Western检测HIF-1与β-actin信号从对照组(3.86±1.98)%增加到(29.46±8.72)%,差异有显著性意义(P<0.01)。结论:低氧可诱导HIF-1α在小鼠胎肝间质细胞中的表达。     

BCR/ABL-mediated increased expression of multiple known and novel genes that may contribute to the pathogenesis of chronic myelogenous leukemia

The BCR/ABL chimeric protein plays a central role in the pathogenesis of chronic myelogenous leukemia (CML). Intensive research has elucidated many signal transduction pathways activated by BCR/ABL. However, few studies addressed BCR/ABL-dependent alterations in gene expression that may contribute to the pathobiology of CML. To additionally define such downstream genes, we performed a subtractive hybridization between cord blood (CB) CD34(+) cells transduced with an MSCV-retrovirus vector containing either enhanced green fluorescent protein (eGFP) alone or p210(BCR/ABL)-internal ribosome entry site-eGFP. Thirty-four subtracted clones expressed in p210-eGFP but not eGFP-transduced CD34(+) cells have been confirmed by Northern blot and sequenced. Fifty-nine percent represent novel proteins, and 41% are homologous to known genes. Quantitative real-time PCR analysis confirmed that 14 of 14 genes tested were also overexpressed in additional populations of p210(BCR/ABL)-transduced CB CD34(+) cells, as well as in CD34(+) cells from primary newly diagnosed CML patients versus GFP-transduced CB or samples from normal donors. Western blot analysis showed that the known sequences were also overexpressed at the protein level. Treatment of BCR/ABL(+) cells with the Abl-specific tyrosine kinase inhibitor STI571 decreased expression at the mRNA as well as protein level of some but not all of the gene products. This suggests that increased gene expression is in some cases tyrosine kinase-independent. Some of the overexpressed genes are implicated in cellular processes known to be disturbed in CML, including the mitogen-activated protein kinase or the ubiquitin pathway, whereas overexpression of other genes, including RAN and NUP98, may implicate new cellular pathways involved in CML. Additional characterization of downstream genes activated by BCR/ABL may lead to important new insights in the molecular mechanisms underlying CML and identify potentially novel therapeutic targets for CML.     

经人巨细胞病毒感染人脐血造血干细胞向粒-巨噬系和红系祖细胞增殖过程中HOXB6-mRNA及其基因表达

背景:造血祖细胞被人巨细胞病毒(HCMV)感染后增殖和分化能力受到抑制是否与受染细胞增殖的基因异常表达有关联?目的:观察经人类巨细胞病毒感染的人类造血干祖细胞向粒-巨噬系、红系祖细胞增殖过程中HOXB6mRNA表达.设计:观察对比实验.单位:泸州医学院附属医院分子生物学实验室.材料:所有脐血标本由泸州医学院附属医院产科提供,取自正常足月顺产新生儿断脐后的胎盘段脐血.所有新生儿母亲HBSAg阴性,常规ELISA检测抗HCMV-IgM及PCR检测HCMV-DNA均为阴性,且对本实验知情同意,实验经过医院伦理委员会批准.HCMV-AD169株由中国预防医学科学院病毒研究所提供.全反式维甲酸(ATRA)为重庆华邦制药股份有限公司产品,批号为20010126.方法:实验于2006-04/2007-04在泸州医学院附属医院分子生物学实验室完成.分离脐血单个核细胞,进行造血祖细胞培养.根据实验干预方式不同将细胞分为4组:[1]对照组:与HCMV组等量的IMDM培养液进行细胞培养.[2]HCMV组:HCMV-AD169滴度为105pfu,以0.1mL感染培养体系.[3]ATRA组:在培养体系分组中加入12μL ATRA,终浓度为60μmol/L.[4]HCMV ATRA组:在HCMV感染组中加入ATRA,终浓度同ATRA组.主要观察指标:分别于培养后3,7,12天收获各组细胞,采用实时荧光定量PCR技术分别检测脐血粒-巨噬系祖细胞和脐血红系祖细胞HOXB6 mRNA表达水平.结果:[1]对照组红系祖细胞和粒-巨噬系祖细胞均表达HOXB6-mRNA,随着时间推移,表达水平增加,其中,脐血红系祖细胞表达HOXB6-mRNA于第12天达高峰,脐血粒-巨噬系祖细胞HOXB6-mRNA于第7天达高峰.[2]HCMV组脐血粒-巨噬系祖细胞、红系祖细胞感染人巨细胞病毒后各时间点HOXB6基因表达均低于对照组,差异有显著性意义(P<0.05).[3]ATRA组各时间点脐血粒-巨噬系祖细胞、红系祖细胞HOXB6-mRNA表达均高于对照组,差异有显著性意义(P<0.05).[4]HCMV ATRA组各时间点红系祖细胞及粒-巨噬系祖细胞的HOXB6-mRNA表达均高于人巨细胞病毒组,差异有显著性意义(P<0.05~0.01).结论:[1]人类造血干祖细胞向粒单系和红系祖细胞增殖分化过程中,HOXB6-mRNA呈现持续稳定的表达.[2]人巨细胞病毒能使HOXB6基因表达下调.[3]ATRA能上调HOXB6基因的表达.     

Angiogenesis is confined to the transient period of VEGF expression that follows adenoviral gene delivery to ischemic muscle

Therapeutic angiogenesis involves the introduction of exogenous growth factor proteins and genes into ischemic tissues to augment endogenous factors and promote new vessel growth. Positive results from studies in animal models of peripheral arterial disease (PAD) and coronary artery disease over the past decade have supported the implementation of clinical trials testing vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) proteins and genes. Although several clinical trials reported positive results, others have been disappointing and results of a recent Phase II trial of VEGF delivered by adenovirus (the RAVE trial) were negative. It has been suggested that the duration of gene expression following delivery by adenovirus may be insufficient to produce stable vessels. Here we present direct evidence in support of this using the rabbit ischemic hindlimb model injected with adenovirus encoding VEGF165. Immunohistology indicated an activation of endothelial cell cycling and proliferation 2-3 days after VEGF delivery that coincided closely with transient VEGF expression. Ki-67-positive endothelial nuclei were evident at high levels in capillaries and large vessels in muscles from treated animals. Angiography indicated increased density of both large and small vessels in Ad-VEGF-treated muscle at 1 week, but no significant differences thereafter. The early burst of endothelial proliferation was accompanied by increased nuclear fragmentation and condensation in VEGF-treated muscles, suggesting coincident apoptosis. No further endothelial cell proliferation took place after 1 week although there was still evidence of apoptosis. The results suggest that angiogenesis is confined to the short period of VEGF expression produced by adenovirus and early gains in collateralization rapidly regress to control levels when VEGF production ceases.