scholarly journals Fetal DNA Clearance from Maternal Plasma Is Impaired in Preeclampsia

2002 ◽  
Vol 48 (12) ◽  
pp. 2141-2146 ◽  
Author(s):  
Tai-Wah Lau ◽  
Tse N Leung ◽  
Lisa YS Chan ◽  
Tze K Lau ◽  
KC Allen Chan ◽  
...  
Keyword(s):  
Maternal Plasma ◽  
Circulating Dna ◽  
First Order ◽  
Real Time Quantitative Pcr ◽  
Fetal Dna ◽  
Significant Difference ◽  
Apparent Clearance ◽  
And Control ◽  
Kinetics Of ◽  
Clearance Model

Abstract Background: Increased fetal DNA in maternal plasma/serum has been reported in pregnancies complicated by preeclampsia. We hypothesized that impaired clearance of fetal DNA might contribute, at least in part, to the above-mentioned phenomenon. Methods: We studied 7 preeclamptic and 10 control pregnant women. All had male fetuses. Serial blood samples were obtained from before delivery to 6 h postpartum. Male fetal DNA in maternal plasma was measured by real-time quantitative PCR for the SRY gene on the Y chromosome. Results: The median fetal DNA concentrations before delivery were significantly higher in the preeclamptic women than in the controls (521 vs 227 genome-equivalents/mL for preeclamptic and control women, respectively; Mann–Whitney rank-sum test, P = 0.017). The median fetal DNA concentrations at 6 h after delivery were also significantly different between the two groups (208 vs 0 genome-equivalents/mL for preeclamptic and control women, respectively; Mann–Whitney rank-sum test, P = 0.002). A first-order clearance model was found to best describe the kinetics of maternal plasma fetal DNA clearance. Moreover, we observed a significant difference in the median apparent clearance half-lives of fetal DNA between the preeclamptic women (114 min) and controls (28 min; Mann–Whitney rank-sum test, P = 0.007). Conclusions: This study represents the first documentation of impaired fetal DNA clearance from maternal plasma in preeclampsia. Such an abnormality in circulating DNA clearance may also be present in other medical conditions associated with quantitative aberrations in circulating DNA concentrations.

scholarly journals REGENERATION OF VISUAL PURPLE IN SOLUTION

1939 ◽  
Vol 23 (1) ◽  
pp. 21-39 ◽  
Author(s):  
Aurin M. Chase ◽  
Emil L. Smith
Keyword(s):  
Order Process ◽  
First Order ◽  
Color Changes ◽  
Violet Light ◽  
Frog Retina ◽  
Significant Difference ◽  
Kinetics Of ◽  
Photosensitive Substance ◽  
Subsequent Regeneration

1. Measurements of visual purple regeneration in solution have been made by a procedure which minimized distortion of the results by other color changes so that density changes caused by the regenerating substance alone are obtained. 2. Bleaching a visual purple solution with blue and violet light causes a greater subsequent regeneration than does an equivalent bleaching with light which lacks blue and violet. This is due to a photosensitive substance which has a gradually increasing effective absorption toward the shorter wavelengths. It is uncertain whether this substance is a product of visual purple bleaching or is present in the solution before illumination. 3. The regeneration of visual purple measured at 560 mµ is maximal at about pH 6.7 and decreases markedly at more acid and more alkaline pH's. 4. The absorption spectrum of the regenerating material shows only a concentration change during the course of regeneration, but has a higher absorption at the shorter wavelengths than has visual purple before illumination. 5. Visual purple extractions made at various temperatures show no significant difference in per cent of regeneration. 6. The kinetics of regeneration is usually that of a first order process. Successive regenerations in the same solution have the same velocity constant but form smaller total amounts of regenerated substance. 7. In vivo, the frog retina shows no additional oxygen consumption while visual purple is regenerating.

scholarly journals Detection of Increased Amounts of Cell-Free Fetal DNA with Short PCR Amplicons

2010 ◽  
Vol 56 (1) ◽  
pp. 136-138 ◽  
Author(s):  
Aleksandra Sikora ◽  
Bernhard G Zimmermann ◽  
Corinne Rusterholz ◽  
Daniella Birri ◽  
Varaprasad Kolla ◽  
...  
Keyword(s):  
Real Time ◽  
Digital Pcr ◽  
Maternal Plasma ◽  
Qpcr Assay ◽  
Detection Capability ◽  
Real Time Quantitative Pcr ◽  
Fetal Dna ◽  
Cell Free Fetal Dna ◽  
Amplicon Size ◽  
Real Time Qpcr

Abstract Aim: A digital PCR approach has recently been suggested to detect greater amounts of cell-free fetal DNA in maternal plasma than conventional real-time quantitative PCR (qPCR). Because the digital qPCR approach uses shorter PCR amplicons than the real-time qPCR assay, we investigated whether a real-time qPCR assay appropriately modified for such short amplicons would improve the detection of cell-free fetal DNA. Method: We developed a novel universal-template (UT) real-time qPCR assay that was specific for the DYS14 sequence on Y chromosome and had a short amplicon size of 50 bp. We examined this “short” assay with 50 maternal plasma samples and compared the results with those for a conventional real-time qPCR assay of the same locus but with a longer amplicon (84 bp). Results: Qualitatively, both assays detected male cell-free fetal DNA with the same specificity and detection capability. Quantitatively, however, the new UT real-time qPCR assay for shorter amplicons detected, on average, almost 1.6-fold more cell-free fetal DNA than the conventional real-time qPCR assay with longer amplicons. Conclusions: The use of short PCR amplicons improves the detection of cell-free fetal DNA. This feature may prove useful in attempts to detect cell-free fetal DNA under conditions in which the amount of template is low, such as in samples obtained early in pregnancy.

Optimized Real-Time Quantitative PCR Measurement of Male Fetal DNA in Maternal Plasma

2006 ◽  
Vol 1075 (1) ◽  
pp. 347-349 ◽  
Author(s):  
B. G ZIMMERMANN ◽  
W. HOLZGREVE ◽  
N. AVENT ◽  
S. HAHN
Keyword(s):  
Real Time ◽  
Quantitative Pcr ◽  
Maternal Plasma ◽  
Real Time Quantitative Pcr ◽  
Fetal Dna

Effect of Different DNA Concentration Methods on Performance of Non-Invasive Fetal Y-Chromosomal Short Tandem Repeat Profiling from Maternal Plasma

2014 ◽  
Vol 37 (1) ◽  
pp. 58-64
Author(s):  
Gabriela Repiská ◽  
Tatiana Sedláčková ◽  
Tomáš Szemes ◽  
Gabriel Minárik
Keyword(s):  
Pregnant Women ◽  
Tandem Repeat ◽  
Short Tandem Repeat ◽  
Maternal Plasma ◽  
Dna Concentration ◽  
Fetal Dna ◽  
Significant Difference ◽  
Short Tandem Repeat Profiling ◽  
Concentration Methods ◽  
Short Tandem

Background: The accuracy and reliability of detection of free fetal DNA in plasma of pregnant women can be significantly improved by increasing the overall DNA concentration following the isolation from maternal plasma. The aim of our study was to compare DNA concentration methods on samples with free fetal DNA. Materials and Methods: DNA isolated from plasma samples of pregnant women carrying a male fetus were concentrated by 3 different methods: vacuum concentration, centrifugal filters and spin columns. Their performance was evaluated using PCR-based Y-chromosomal short tandem repeat (Y-STR) genotyping of the fetus. Results: A statistically significant difference was found between the 3 tested methods (F = 15.57, p < 0.0001). Using vacuum concentration 85.3% of paternally inherited Y-STR alleles were correctly identified. A significantly smaller proportion of alleles was correctly identified in samples concentrated by centrifugal filters and spin columns - 75.9 and 66.5%, respectively. Discussion: The highest proportion of paternally inherited Y-STR alleles was found in samples concentrated with the use of vacuum concentration. This concentration procedure does not require further handling of the sample either, which is an advantage because it avoids potential sample contamination. On the other hand, when automation is considered, vacuum concentration is less suitable because of an uneven and unpredictable sample evaporation rate.

Selection of the optimal manual method of cell free fetal DNA isolation from maternal plasma

2013 ◽  
Vol 51 (6) ◽  
Author(s):  
Gabriela Repiská ◽  
Tatiana Sedláčková ◽  
Tomáš Szemes ◽  
Peter Celec ◽  
Gabriel Minárik
Keyword(s):  
Maternal Plasma ◽  
Alternative Source ◽  
Non Invasive ◽  
Fetal Dna ◽  
Optimized Protocol ◽  
Spin Column ◽  
Cell Free Fetal Dna ◽  
Significant Difference ◽  
Two Phases ◽  
Selection Of

AbstractThe cell free fetal DNA (cffDNA) present in plasma of pregnant women represents an important alternative source of DNA for non-invasive prenatal diagnosis. Due to the low quantity and increased fragmentation of cffDNA, the choice of DNA extraction method is a crucial step for downstream analyses.In our study, the three spin column-based kits for isolation of cffDNA [DNA Blood Mini Kit (DBM), DSP Virus Kit (DSP) and Circulating Nucleic Acid (CNA) Kit] were compared. Original and optimized protocol were used in comparison and applied in the two phases of the study.A statistically significant difference in performance of the kits was determined based on the comparison of genomic equivalents per mL (GEq/mL) values (p<0.0001). The GEq/mL of isolated DNA was significantly higher using CNA and DSP Kits than DBM Kit. The CNA Kit and DSP Kit did not significantly differ in the GEq/mL values, although all tested samples isolated with CNA Kit showed higher values.According to our results the commonly used DBM Kit could be successfully replaced with CNA or DSP Kits. The replacement could be beneficial in qualitative as well quantitative tests (e.g., gender determination, aneuploidy detection) when the isolation yield limits subsequent analyses. However, there is an important decision to be made when switching DBM Kit for DSP or CNA Kits. The price of DBM Kit is two and six times lower than DSP and CNA Kits, respectively.

scholarly journals Quantitative Abnormalities of Fetal DNA in Maternal Serum in Preeclampsia

1999 ◽  
Vol 45 (2) ◽  
pp. 184-188 ◽  
Author(s):  
YM Dennis Lo ◽  
Tse N Leung ◽  
Mark SC Tein ◽  
Ian L Sargent ◽  
Jun Zhang ◽  
...  
Keyword(s):  
Human Subjects ◽  
Model System ◽  
Maternal Serum ◽  
Circulating Dna ◽  
Sry Gene ◽  
Real Time Quantitative Pcr ◽  
Fetal Dna ◽  
Recent Interest ◽  
Circulating Fetal Dna ◽  
Pathologic Processes

Abstract Background: There is much recent interest in the biologic and diagnostic implication of cell-free non-host DNA in the plasma and serum of human subjects. To determine if quantitative abnormalities of circulating non-host DNA may be associated with certain pathologic processes, we used circulating fetal DNA in preeclampsia as a model system. Methods: We studied 20 preeclamptic women and 20 control subjects of comparable gestational age (means, 32 and 33 weeks, respectively). Male fetal DNA in maternal serum was measured using real-time quantitative PCR for the SRY gene on the Y chromosome. Results: The imprecision (CV) of the assay was 2.7%. The median circulating fetal DNA was increased fivefold in 20 preeclamptic women compared with 20 control pregnant women (381 vs 76 genome-equivalents/mL, P &lt;0.001). Conclusions: These observations suggest that preeclampsia is associated with disturbances in the liberation and/or clearance mechanisms of circulating DNA. These results also raise the possibility that measurement of circulating DNA may prove useful as a marker for the diagnosis and/or monitoring of preeclampsia.

scholarly journals Optimized Real-Time Quantitative PCR Measurement of Male Fetal DNA in Maternal Plasma

2005 ◽  
Vol 51 (9) ◽  
pp. 1598-1604 ◽  
Author(s):  
Bernhard Zimmermann ◽  
Ahmad El-Sheikhah ◽  
Kypros Nicolaides ◽  
Wolfgang Holzgreve ◽  
Sinuhe Hahn
Keyword(s):  
Real Time ◽  
Quantitative Pcr ◽  
Pcr Amplification ◽  
First Trimester ◽  
Single Copy ◽  
Maternal Plasma ◽  
Probit Regression ◽  
Real Time Quantitative Pcr ◽  
Fetal Dna ◽  
First Trimester Of Pregnancy

Abstract Background: Circulating fetal DNA (cfDNA) in maternal plasma has been measured to investigate its possible relationship with pregnancy-related disorders, including fetal trisomy 21 and preeclampsia. The circulating concentrations of single-copy fetal genes, however, are close to the detection limits of PCR methods. Methods: We optimized a protocol for the real-time quantitative PCR amplification of the multicopy sequence DYS14 on the Y-chromosome. This was compared with an established real-time PCR assay for the single-copy SRY gene. Results: By probit regression analysis, the measurements of male DNA by the DYS14 assay had a 10-fold lower detection limit (0.4 genome equivalents) than did measurements of SRY. For plasma samples from women in the first trimester of pregnancy, imprecision (CV) was 2%–22% when amplifying DYS14 compared with 26%–140% for SRY. Conclusions: The low copy numbers of fetal DNA in plasma of women in the first trimester of pregnancy cannot be measured precisely when targeting single-copy sequences. Better results are obtained by amplifying a sequence that is present in multiple copies per male genome.

Investigation of irradiation-induced nucleation processes in silicon and germanium

1995 ◽  
Vol 53 ◽  
pp. 224-225
Author(s):  
Harry A. Atwater ◽  
C.M. Yang ◽  
K.V. Shcheglov
Keyword(s):  
Room Temperature ◽  
Crystal Size ◽  
Initial Distribution ◽  
Engineering Control ◽  
Size Evolution ◽  
Silicon And Germanium ◽  
Ge Quantum Dot ◽  
And Control ◽  
Germanium Quantum Dots ◽  
Kinetics Of

Studies of the initial stages of nucleation of silicon and germanium have yielded insights that point the way to achievement of engineering control over crystal size evolution at the nanometer scale. In addition to their importance in understanding fundamental issues in nucleation, these studies are relevant to efforts to (i) control the size distributions of silicon and germanium “quantum dots𠇍, which will in turn enable control of the optical properties of these materials, (ii) and control the kinetics of crystallization of amorphous silicon and germanium films on amorphous insulating substrates so as to, e.g., produce crystalline grains of essentially arbitrary size.Ge quantum dot nanocrystals with average sizes between 2 nm and 9 nm were formed by room temperature ion implantation into SiO2, followed by precipitation during thermal anneals at temperatures between 30°C and 1200°C[1]. Surprisingly, it was found that Ge nanocrystal nucleation occurs at room temperature as shown in Fig. 1, and that subsequent microstructural evolution occurred via coarsening of the initial distribution.

Functional Fractionation of Platelets: Aggregation Kinetics and Glycoprotein Labeling of Differing Platelet Populations

1982 ◽  
Vol 48 (02) ◽  
pp. 211-216 ◽  
Author(s):  
V M Haver ◽  
A R L Gear
Keyword(s):  
Galactose Oxidase ◽  
Aggregation Kinetics ◽  
Maximal Rate ◽  
Membrane Glycoproteins ◽  
Whole Cells ◽  
Reversible Aggregation ◽  
Significant Difference ◽  
Small Doses ◽  
Major Loss ◽  
Kinetics Of

SummaryPlatelet heterogeneity has been studied with a technique called functional fractionation which employs gentle centrifugation to yield subpopulations (“reactive” and “less-reactive” platelets) after exposure to small doses of aggregating agent. Aggregation kinetics of the different platelet populations were investigated by quenched-flow aggregometry. The large, “reactive” platelets were more sensitive to ADP (Ka = 1.74 μM) than the smaller “less-reactive” platelets (Ka = 4.08 μM). However, their maximal rate of aggregation (Vmax, % of platelets aggregating per sec) of 23.3 was significantly lower than the “less-reactive” platelets (Vmax = 34.7). The “reactive” platelets had a 2.2 fold higher level of cyclic AMP.Platelet glycoproteins were labeled using the neuraminidase-galactose oxidase – [H3]-NaBH4 technique. When platelets were labeled after reversible aggregation, the “reactive” platelets showed a two-fold decrease in labeling efficiency (versus control platelets). However, examination of whole cells or membrane preparations from reversibly aggregated platelets revealed no significant difference in Coomassie or PAS (Schiff) staining.These results suggest that the large, “reactive” platelets are more sensitive to ADP but are not hyperaggregable in a kinetic sense. Reversible aggregation may cause a re-orientation of membrane glycoproteins that is apparently not characterized by a major loss of glycoprotein material.

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