中国汉族群体vWF基因40内含子VNTR

本文将Ａｍｐ－ＦＬＰ与ＲＦＬＰ结合起来,检测ｖＷＦ基因４０内含子ＶＮＴＲ。调查长沙地区１５６名无亲缘关系汉族人,发现ｖＷＦ基因４０内含子ＶＮＴＲ基因１３６个。基因型１５２个,全部为杂合子,分布符合Ｈａｒｄｙ－Ｗｅｉｎｂｅｒｇ平衡定律。此ＶＮＴＲ杂合率为０．９８８４,ＰＩＣ为０．９８８３,是现已检出Ａｍｐ－ＦＬＰ中多态性最高的遗传标记。家系分析显示ＶＮＴＲ无遗传重组,依照常染色体共显性遗传。用高分辨     

A noninvasive approach to studying fetal cells for prenatal diagnosis of chromosomal aneuploidies

Fetal cells isolated from maternal peripheral blood during the second trimester of pregnancy were analyzed. Blood samples were centrifuged in a Ficoll-Paque gradient, the mononuclear cell fraction was isolated and stained with fluorescent monoclonal antibodies against glycophorine A (GPA + PE), transferrin (CD71 + FITC), and Hoechst 33342. Fluorescence-activated cell sorting (FACS) was conducted on a Vantage flow cytofluorimeter (Becton Dickinson). Fluorescence in situ hybridization (FISH) with Y chromosome-specific DNA probe revealed fetal cells that exhibited Y signal in all 20 blood samples obtained from women pregnant with healthy male fetuses. The concentration of these fetal cells averaged about 1.34% and ranged from 0.1 to 4.2% in different blood samples. In six cases, blood samples were obtained from pregnant women, in which prenatal cytogenetic analysis revealed various fetal aneuploidies. Using FISH with DNA probes specific for chromosomes X, 18, and 13/21, Fetal cells with chromosomal aberrations were detected in these six maternal blood samples at a concentration from 1.5 to 5.6% (on average 3.7%). These results indicate the possibility of a new noninvasive approach, which is safe for both mother and fetus when used for isolation of fetal cells from pregnant women's blood samples and prenatal diagnosis of a broad spectrum of fetal cell chromosomal aberrations.     

Mouse fetal hemoglobin.

Using isoelectric focusing, a fetal hemoglobin was found in the peripheral blood of C57BL/6 fetal mouse during the 14 to 20 days gestational period. In acid-urea polyacrylamide gel the pattern of this fetal hemoglobin was different from that of the adult hemoglobin. The mouse fetal hemoglobin was differentiated from the mouse adult hemoglobin by immunodiffusion reaction. It suggests that there is a transient fetal hemoglobin in the C57BL/6 mouse during gestational age.     

Prenatal diagnosis of ornithine transcarbamylase deficiency by using a single nucleated erythrocyte from maternal blood

We have developed a method that allows the prenatal DNA diagnosis of ornithine transcarbamylase (OTC) deficiency by using a single fetal nucleated erythrocyte (NRBC) isolated from maternal blood. OTC gene analysis of a male patient (TF) with early onset OTC deficiency was performed by single-strand conformation polymorphism (PCR-SSCP) and DNA sequencing. To investigate the possible prenatal diagnosis of OTC deficiency, maternal blood was obtained at 13 weeks of gestation of a subsequent pregnancy, from the mother of patient TF. NRBCs in the maternal blood were separated by using the density gradient method and then collected with a micromanipulator. The entire genome of a single NRBC was amplified by primer extension preamplification (PEP). The human leukocyte antigen (HLA)-DQ alpha genotype and sex were determined from small aliquots of the PEP product. The HLA-DQ alpha genotype of each of the parents of the male patient was also determined. Once a single NRBC had been identified as being of fetal origin, the OTC gene was analyzed by using the restriction fragment length polymorphism (RFLP) method. DNA analysis revealed a point mutation in exon 9 of the OTC gene in the OTC-deficient patient (TF). All NRBCs retrieved from maternal blood were successfully identified as being of fetal origin by HLA-DQ alpha genotyping and sex determination. RFLP analysis demonstrated that the fetal OTC gene was normal. This is the first study to successfully diagnose OTC deficiency prenatally, by using a single fetal NRBC from the maternal circulation. Such prenatal DNA diagnosis is non-invasive and can be applied to other genetic diseases, including autosomal and X-linked diseases. Received: 19 December 1997 / Accepted: 14 February 1998     

Search for the optimal fetal cell antibody: results of immunophenotyping studies using flow cytometry

Fetal nucleated cells circulating in maternal peripheral blood are a noninvasive source of fetal DNA for prenatal genetic diagnoses. The successful isolation of fetal cells from maternal blood depends upon identification of differences between fetal and maternal cell surface antigen expression. To our best knowledge, a monoclonal antibody that binds only fetal blood cells has not yet been identified. We studied antigens recognized by six different monoclonal antibodies for their biologic expression on fetal blood cells as a function of gestational age, and compared their ability to bind fetal but not maternal cells. The results suggest a relationship between gestational age and nucleated cell surface antigen expression. The monoclonal antibodies FB3-2, H3-3, CD71 and 2-6B/6 are suitable reagents for first or early second trimester fetal cell isolation, although FB3-2 and H3-3 are more specific for fetal cells due to significantly lower expression of these antigens on maternal mononuclear cells. The observation that samples from fetuses with chromosome abnormalities or multiple structural anomalies express higher levels of these antigens indicates that these reagents will potentiate the detection of abnormal fetal cells in maternal blood samples. Received: 23 November 1996 / Accepted: 13 February 1997     

Multiple testing in fetal gender determination from maternal blood by polymerase chain reaction

Fetal male DNA can be identified in maternal blood by polymerase chain reaction (PCR) amplification of Y-specific sequences. This technology has not reached a satisfactory accuracy and reproducibility in fetal gender determination because of the very low concentration of fetal cells. Our purpose was to evaluate the possibility of improving the reliability of this test by setting up a repeated amplification system. We amplified, by nested PCR of the Y-specific sequence DYS14, 137 DNA samples extracted from maternal peripheral blood (93 from male-bearing and 44 from female-bearing pregnancies ranging from the 6th to the 36th gestational week). Each maternal DNA sample was tested doubly, in two different PCR sessions, with a total of four amplifications. We obtained discordant results in the four amplifications in 82/137 (60%) samples. The best interpretation of these discordant results was obtained by applying a positivity cutoff of at least two positive amplifications for considering a DNA sample as belonging to a male-bearing pregnancy. We obtained a sensitivity of 83%, a specificity of 93%, a positive predictive value of 96% and a negative predictive value of 72% in fetal male gender diagnosis. By applying this quadruple testing system, we significantly improved PCR accuracy and predictive values compared with single and double testing of the same samples. We conclude that, for future investigations of fetal DNA retrieved from maternal blood, the application of a quadruple testing system is better than the single PCR test. Received: 18 August 1997 / Accepted: 12 January 1998     

Pregnancy-associated esterase in sera of baboons

Baboon serum samples were resolved by starch gel electrophoresis and polyacrylamide gradient gel electrophoresis and stained with naphthol substrates for esterase activity. An esterase that hydrolyzed alpha-naphthyl butyrate in preference to alpha-naphthyl acetate was found in very high activities in some individuals but not others. It migrated just cathodal of the albumin band in starch gels. In polyacrylamide gradient gels, it co-migrated with albumin and had an apparent molecular weight of approximately 65,000 daltons. Electrophoretic analysis by gel electrophoresis of random serum samples from male and female baboons indicated that this esterase was present only in the sera of pregnant baboons. Further investigation of serial samples collected from carefully monitored baboons confirmed that the amount of activity of this esterase was correlated with stage of pregnancy. Therefore, it was named pregnancy esterase (PE). PE was detectable by gel electrophoresis and chromogenic staining techniques as early as day 30 of pregnancy; its activity gradually increased with progressive pregnancy and reached maximum activity near full term (182 days). Soon after parturition, the activity of PE decreased rapidly and was not detected in maternal sera by day 14 postpartum. No evidence of PE was detected in sera of pregnant humans.     

Quantitative analysis of DNA aberrations amplified by competitive polymerase chain reaction using capillary electrophoresis

We compared the use of capillary electrophoresis (CE) in a polymer network with the use of slab gel electrophoresis for the quantitative analysis of polymerase chain reaction (PCR)-amplified DNA samples. We quantified residual lymphoma cells carrying a translocation between chromosomes 14 and 18, in consecutive patient peripheral blood samples that were amplified by competitive PCR. For CE analysis we used a 4% linear polyacrylamide network. Results show that the calculated number of translocations in patient samples using both analyses were comparable. We conclude that CE is a sensitive, non-radioactive, fast and accurate method for quantitation of competitive PCR products.     

Female fetal cells in maternal blood: use of DNA polymorphisms to prove origin

The nucleated erythrocyte (NRBC) is one of the target fetal cell types for noninvasive genetic diagnosis using maternal peripheral blood. However, it is now known that pregnancy can stimulate the production of maternal NRBCs. When isolating female gamma-positive NRBCs, fluorescence in situ hybridization (FISH) analysis may show two X chromosome signals per nucleus, and therefore it cannot be conclusively determined whether the isolated cells are fetal or maternal in origin. The purpose of this study was to develop a means of verifying that a female cell is fetal on the basis of polymorphic short tandem repeat markers. Peripheral blood samples were obtained from women who had just undergone termination of pregnancy. Nucleated candidate fetal cells were isolated by flow-sorting using antibody to the gamma-chain of fetal hemoglobin and Hoechst 33342. FISH analysis was performed using X and Y chromosome specific probes. Female gamma-positive cells and leukocytes were micromanipulated separately and subjected to fluorescent polymerase chain reaction amplification of chromosome 21 and/or 18 STR markers (D21S11, D21S1411, D21S1412, and D18S535). In all ten cases analyzed, the gamma-positive female candidate fetal cells were determined to be fetal in origin by the presence of shared and nonshared DNA polymorphisms when compared with maternal leukocytes. These results show that genetic analysis can be performed on all fetal NRBCs, including female fetal cells that cannot be distinguished from maternal cells based on FISH analysis alone.     

The use of non-physiological conditions to isolate fetal cells from maternal blood

Fetal cells are always present in maternal blood starting in the first trimester of pregnancy, however a rapid, simple, and consistent procedure for their isolation for prenatal non-invasive genetic investigation is still lacking. Sensitivity and recovery of fetal cells is jeopardized by the minute amount of circulating fetal cells and their loss during the enrichment procedure. We report here a single-step approach to isolate fetal cells from maternal blood which relies on the use of non-physiological conditions to modify cell densities before their separation in a density gradient and in a newly developed cell separation device. Isolated fetal cells have been investigated using cytochemistry, Soret band absorption microscopy, monoclonal antibodies for epsilon- and gamma-chain-Hb, monoclonal antibody for i-antigen, and by fluorescence in situ hybridization (FISH). Fetal cells were always detected in all 105 maternal blood samples investigated and fetal aneuploidies were correctly diagnosed by FISH, in a pilot study of pathological pregnancies, in fetal cells isolated from maternal blood obtained either before or after invasive procedure.     

Analysis of HLA-DQ α sequences for prenatal diagnosis in single fetal cells from maternal blood

We have extended a previously developed method that allows prenatal DNA diagnosis of female fetuses through the isolation of single nucleated erythrocytes from maternal blood by developing a method that can distinguish between maternal and fetal nucleated erythrocytes. Nucleated erythrocytes were separated by a density-gradient method and then collected by micromanipulation. Sex was determined after primer extension preamplification (PEP) of the entire genome of a single cell, and human leukocyte antigen (HLA)-DQ α type was determined after further amplification of this gene. The HLA-DQ α genotype of fetal erythrocytes in maternal blood samples and their corresponding paternal and maternal lymphocytes were successfully determined in all cases. The accuracy of the method was determined by using single nucleated erythrocytes from umbilical cord blood from five normal deliveries. This is the first demonstration that the fetal HLA-DQ α gene sequences can be identified in a small aliquot of a single nucleated erythrocyte in maternal blood. We believe that this method ushers in a new era in which the reliability and accuracy of noninvasive prenatal DNA diagnosis from maternal blood is markedly improved. Received: 18 April 1997 / Accepted: 1 October 1997     

一种改进的异硫氰酸胍法结合硅胶膜离心吸附柱提取孕妇外周血微量胎儿RNA的方法

孕妇外周血中存在胎儿RNA为无创性产前诊断提供了基础.但血液中富含RNA酶和微量胎儿RNA的特点,对从孕妇血浆中提取胎儿RNA带来困难. 我们以ε血红蛋白基因和胎盘特异表达基因4（PLAC4）mRNA作为研究对象,用改进的异硫氰酸胍法结合硅胶膜离心吸附柱法探索孕妇外周血中胎儿微量RNA的提取方法,获得满意效果. 30例孕妇和9例非孕妇外周血样品中总RNA经凝胶电泳测定显示3条带,分别为28S, 18S和 5.8S. 其28S条带亮度为18S亮度的2倍.总RNA质量浓度（A260／A280）为1.97 g/L,光密度比值(A260-A320）/（A280- A 320）为1.86. 30例孕妇外周血样本有7例提取到ε血红蛋白基因mRNA,ε血红蛋白基因 mRNA 的最小浓度为0.537 μg/mL,最大浓度为1.79 μg/mL,ε血红蛋白基因mRNA的浓度中位数为124 μg/mL. 30例孕妇外周血样本提取到PLAC4 基因mRNA,浓度最小值为2.105×103 copies/mL,最大值为12.760×103 copies/mL,而9例非孕妇中均未提取到（P＜0.01）,浓度中位数为6.612×103 copies/mL. 因此,改进的异硫氰酸胍法与硅胶膜离心吸附柱纯化法相结合,可有效抑制RNA降解,用于提取、纯化孕妇血液中微量胎儿RNA.     

Maternal origin of nucleated erythrocytes in peripheral venous blood of pregnant women

We studied the origin of nucleated red blood cells (NRBC) in peripheral venous blood samples from 40 pregnant women carrying a male fetus, using a technique that allows direct chromosomal analysis by in situ hybridisation on immunologically and morphologically classified cells. Samples from ten nulligravid women were studied as controls. NRBC were enriched by negative magnetic activated cell sorting (miniMACS) using anti-CD45 monoclonal antibody. NRBC were detected by alkaline phosphatase anti-alkaline phosphatase immunostaining using a monoclonal anti-glycophorin A antibody. The origin of the NRBC was determined by fluorescence in situ hybridisation using X and Y specific probes. NRBC were found in 37 of the 40 pregnant women at a range of 1 to 230 per 20 ml of venous blood and in 6 of the 10 controls at a range of 1 to 3 per 20 ml of venous blood. All NRBC detected in the pregnant women were evidently of maternal origin, and in the pregnant women the number of NRBC was significantly higher (P < 0.05) than in the controls. Pregnancy per se seems to induce the appearance of maternal NRBC in the circulation, and it cannot therefore be assumed that NRBC isolated from the maternal blood are of fetal origin on the basis of morphology alone. Discrimination of fetal NRBC must occur for prenatal diagnosis of fetal genetic disorders.     

PCR quantitation of fetal cells in maternal blood in normal and aneuploid pregnancies.

Fetal cells in maternal blood are a noninvasive source of fetal genetic material for prenatal diagnosis. We determined the number of fetal-cell DNA equivalents present in maternal whole-blood samples to deduce whether this number is affected by fetal karyotype. Peripheral blood samples were obtained from 199 women carrying chromosomally normal fetuses and from 31 women with male aneuploid fetuses. Male fetal-cell DNA-equivalent quantitation was determined by PCR amplification of a Y chromosome-specific sequence and was compared with PCR product amplified from known concentrations of male DNA run simultaneously. The mean number of male fetal-cell DNA equivalents detected in 16-ml blood samples from 90 women bearing a 46,XY fetus was 19 (range 0-91). The mean number of male fetal-cell DNA equivalents detected in 109 women bearing a 46,XX fetus was 2 (range 0-24). The mean number of male fetal-cell DNA equivalents detected when the fetus was male compared with when the fetus was female was highly significant (P = .0001). More fetal cells were detected in maternal blood when the fetus was aneuploid. The mean number of male fetal-cell DNA equivalents detected when the fetal karyotype was 47,XY,+21 was 110 (range 0.1-650), which was significantly higher than the number of male fetal-cell DNA equivalents detected in 46,XY fetuses (P = .0001). Feto-maternal transfusion of nucleated cells appears to be influenced by fetal karyotype. The sixfold elevation of fetal cells observed in maternal blood when the fetus had trisomy 21 indicates that noninvasive cytogenetic diagnosis of trisomy 21 should be feasible.     

从非变性聚丙烯酰胺凝胶回收纯化DNA样本

介绍一种从非变性聚丙烯酰胺凝胶中回收和纯化目标DNA片段的方法,经比较回收纯化前后PCR产物的电泳结果,表明该方法具有简单快捷和效率高的优点。     

DNA extraction from coral reef sediment bacteria for the polymerase chain reaction

A rapid and effective method for the direct extraction of high molecular weight amplifiable DNA from two coral reef sediments was developed. DNA was amplified by the polymerase chain reaction (PCR) using 16S rDNA specific primers. The amplicons were digested with HaeIII, HinP1I and MspI and separated using polyacrylamide gel electrophoresis and silver staining. The resulting amplified ribosomal DNA restriction analysis (ARDRA) patterns were used as a fingerprint to discern differences between the coral reef sediment samples. Results indicated that ARDRA is an effective method for determining differences within the bacterial community amongst different environmental samples.     

Purification and partial sequence of human osteoclast-activating factor: identity with interleukin 1 beta

The lymphokine osteoclast-activating factor (OAF) was purified to homogeneity. OAF was produced by human peripheral blood mononuclear cells stimulated with concanavalin A and phorbol myristate acetate under serum-free culture conditions. OAF was purified by sequential gel filtration, ion-exchange, and reverse-phase HPLC by following bone resorptive activity. Homogeneity was indicated by the criteria of a single 17,800-dalton band on silver-stained polyacrylamide gels, a single pI 6.8 band on isoelectric focusing, and a single aminoterminal sequence. Purified OAF stimulated half-maximal release of calcium from fetal rat long bones at a concentration of approximately 0.66 ng/ml. The amino-terminal sequence of OAF was determined and found to be identical to that of interleukin 1 beta. Homogeneous OAF possessed an activity of 8.2 X 10(6) U/mg in the thymocyte proliferation assay. Because the m.w., isoelectric point, amino-terminal sequence, and specific activity in the thymocyte proliferation assay are the same for homogeneous OAF and interleukin 1 beta, we conclude that they are the same molecule, and that interleukin 1 beta is the major protein with OAF activity produced by lectin-stimulated peripheral blood mononuclear cells.     

应用胎儿特异性抗体HbF（γ链）标记法无创性 产前基因诊断DMD

以孕8~26周孕妇外周血为材料,经过Percoll密度梯度离心初步富集,胎儿细胞特异性抗体—HbF标记、识别胎儿有核红细胞,母体和胎儿有核红细胞的精确区分是以胎儿和成人血红蛋白的组成差异为基础的。胎儿细胞胞浆黄染,而具有成人血红蛋白的母体细胞没有颜色。显微操作法获取全部阳性细胞后,以其全基因组扩增（PEP）的产物为模板,进行性别检测、DMD基因的多重PCR检测和STR连锁分析。结果,20名孕妇外周血中均发现与HbF呈阳性反应的胎儿NRBC。并完成7例DMD的产前基因诊断。HbF抗体标记法能有效识别胎儿有核红细胞,是无创性产前基因诊断中很有应用前景的标记方法。 Abstract： Maternal blood was obtained at 8-26weeks of gestation.After discontinuous density gradient centrifugation with Percoll ,HbF antibody was used to identify fetal NRBC.The precise differentiation between fetal and maternal NRBC is based on the constitutional difference between fetal and adult hemoglobin (Hb).Fetal cells appear yellow cytoplasmic staining,while adult cells colorless. NRBCs were collected by micromanipulation andwhole genome amplification was performed. DMD was prenatally diagnosed by using the combination of sex determination,multiplex PCR and linkage analysis of several STR sites of dystrophin. NRBCs stained with HbF were found in all of 20 maternal blood samples with gestations, and 7 fetuses with risk of DMD were diagnosed. We concluded that HbF antibody could identify fetal NRBC efficaciously,and this is a kind of more prospective application method.     

Multiple-locus variable-number tandem repeat analysis of Legionella pneumophila using multi-colored capillary electrophoresis

Several methods for typing of Legionella pneumophila exist, one of which is an 8-locus variable-number of tandem repeats analysis (MLVA). This method is based on separating and sizing amplified VNTR PCR products by agarose gel electrophoresis. In the present work, the existing L. pneumophila MLVA-8 assay is adapted to capillary electrophoresis. The assay was multiplexed by using multiple fluorescent labeling dyes and tested on a panel of L. pneumophila strains with known genotypes. The results from the capillary electrophoresis-based assay are shown to be equivalent to, and in a few cases more sensitive than, the gel-based genotyping assay. The assay presented here allows for a swift, automated and precise typing of L. pneumophila from patient or environmental samples and represents an improvement over the current gel-based method.     

Presence of fetal DNA in maternal plasma decades after pregnancy

Cells of fetal origin and cell-free fetal DNA can be detected in the maternal circulation during pregnancy, and it has recently been shown that fetal cells can persist long after delivery. Given the various biological and clinical implications of this fact, we tested the hypothesis that cell-free fetal DNA can be present in maternal plasma decades after pregnancy. We extracted DNA from plasma samples and nucleated blood cells of 160 healthy women with male offspring at different time intervals after delivery (range 1-60 years). All of the samples were tested by means of a real-time quantitative PCR assay for a specific Y chromosome sequence (the SRY gene). Y chromosome-specific DNA was detected in 16 peripheral blood cell samples (10%) and 35 plasma samples (22%). The women with male sequences in the cell fraction had significantly greater total parity ( P=0.018). The proportion of women with detectable Y sequences in the plasma or cell samples was not related to the time since delivery. The fetal DNA concentrations in the genomic material extracted from plasma samples were significantly higher than those extracted from the Y-positive cell samples (149+/-140 vs 20+/-13 genome-equivalents/ml; P<0.001). There was no relationship between the concentration of fetal DNA and the time since delivery. Not only fetal cells, but also fragments of fetal DNA can be present in the maternal circulation indefinitely after pregnancy. This finding has practical implications for non-invasive prenatal diagnoses based on maternal blood, and may be considered for possible pathophysiological correlations.