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1.  The dilution effect and the importance of selecting the right internal control genes for RT-qPCR: a paradigmatic approach in fetal sheep 
BMC Research Notes  2015;8:58.
The key to understanding changes in gene expression levels using reverse transcription real-time quantitative polymerase chain reaction (RT-qPCR) relies on the ability to rationalize the technique using internal control genes (ICGs). However, the use of ICGs has become increasingly problematic given that any genes, including housekeeping genes, thought to be stable across different tissue types, ages and treatment protocols, can be regulated at transcriptomic level. Our interest in prenatal glucocorticoid (GC) effects on fetal growth has resulted in our investigation of suitable ICGs relevant in this model. The usefulness of RNA18S, ACTB, HPRT1, RPLP0, PPIA and TUBB as ICGs was analyzed according to effects of early dexamethasone (DEX) treatment, gender, and gestational age by two approaches: (1) the classical approach where raw (i.e., not normalized) RT-qPCR data of tested ICGs were statistically analyzed and the best ICG selected based on absence of any significant effect; (2) used of published algorithms. For the latter the geNorm Visual Basic application was mainly used, but data were also analyzed by Normfinder and Bestkeeper. In order to account for confounding effects on the geNorm analysis due to co-regulation among ICGs tested, network analysis was performed using Ingenuity Pathway Analysis software. The expression of RNA18S, the most abundant transcript, and correlation of ICGs with RNA18S, total RNA, and liver-specific genes were also performed to assess potential dilution effect of raw RT-qPCR data. The effect of the two approaches used to select the best ICG(s) was compared by normalization of NR3C1 (glucocorticoid receptor) mRNA expression, as an example for a target gene.
Raw RT-qPCR data of all the tested ICGs was significantly reduced across gestation. TUBB was the only ICG that was affected by DEX treatment. Using approach (1) all tested ICGs would have been rejected because they would initially appear as not reliable for normalization. However, geNorm analysis (approach 2) of the ICGs indicated that the geometrical mean of PPIA, HPRT1, RNA18S and RPLPO can be considered a reliable approach for normalization of target genes in both control and DEX treated groups. Different subset of ICGs were tested for normalization of NR3C1 expression and, despite the overall pattern of the mean was not extremely different, the statistical analysis uncovered a significant influence of the use of different normalization approaches on the expression of the target gene. We observed a decrease of total RNA through gestation, a lower decrease in raw RT-qPCR data of the two rRNA measured compared to ICGs, and a positive correlation between raw RT-qPCR data of ICGs and total RNA. Based on the same amount of total RNA to performed RT-qPCR analysis, those data indicated that other mRNA might have had a large increase in expression and, as consequence, had artificially diluted the stably expressed genes, such as ICGs. This point was demonstrated by a significant negative correlation of raw RT-qPCR data between ICGs and liver-specific genes.
The study confirmed the necessity of assessing multiple ICGs using algorithms in order to obtain a reliable normalization of RT-qPCR data. Our data indicated that the use of the geometrical mean of PPIA, HPRT1, RNA18S and RPLPO can provide a reliable normalization for the proposed study. Furthermore, the dilution effect observed support the unreliability of the classical approach to test ICGs. Finally, the observed change in the composition of RNA species through time reveals the limitation of the use of ICGs to normalize RT-qPCR data, especially if absolute quantification is required.
Electronic supplementary material
The online version of this article (doi:10.1186/s13104-015-0973-7) contains supplementary material, which is available to authorized users.
PMCID: PMC4352295  PMID: 25881111
Dexamethasone; Sheep; Fetal liver; geNorm; Co-regulation; Internal control gene; RNA18S; RPLP0; HPRT1; PPIA; TUBB; ACTB; RNA28S
3.  Supplementation with 200 mg/Day Docosahexaenoic Acid from Mid-Pregnancy through Lactation Improves the Docosahexaenoic Acid Status of Mothers with a Habitually Low Fish Intake and of Their Infants 
Annals of Nutrition & Metabolism  2008;52(2):157-166.
The supply of docosahexaenoic acid (DHA, 22:6ω–3), important for fetal/infant neurodevelopment, depends on the maternal fatty acid (FA) status, which may be marginal in central Europe. Therefore, we investigated the effect of a daily vitamin/mineral supplement with and without 200 mg DHA from mid-pregnancy through lactation on the DHA concentrations in maternal and infant red blood cell phospholipids (RBC%), and in breast milk FA (%).
At 21 weeks’ gestation, 144 women were enrolled into a randomised, double-blind clinical trial receiving daily: (1) a basic vitamin-mineral supplement (Vit/Min group), (2) Vit/Min plus 4.5 g fructo-oligosaccharide (FOS group), or (3) Vit/Min plus 4.5 g FOS plus 200 mg fish oil-derived DHA (DHA-FOS group). FAs were determined by capillary gas-liquid chromatography.
While maternal RBC-DHA% at enrolment was not different, at 37 weeks gestation, and 3 months after delivery RBC-DHA% were significantly higher in the DHA-FOS group. The breast milk DHA% was twice as high in the DHA-FOS group (0.50%) than in the two others (0.25 %) (p < 0.001), and the ratio ARA/DHA in the DHA-FOS group was 1.0 ± 0.43, in the others 2.1 ± 0.43 (p < 0.001). The RBC-DHA% of the infants in the DHA-FOS group was also significantly higher, and correlated significantly with maternal RBC-DHA% before and 3 months after delivery.
In central Europe, a dose of 200 mg/day DHA from mid-pregnancy through lactation seems appropriate to improve the DHA status of mothers and infants.
PMCID: PMC2790529  PMID: 18446020
Supplements; Docosahexaenoic acid; Pregnancy; Lactation; Concentration; Erythrocytes; Breast milk
4.  Preconceptional factors associated with very low birthweight delivery in East and West Berlin: a case control study 
BMC Public Health  2002;2:10.
Very low birthweight, i.e. a birthweight < 1500 g, is among the strongest determinants of infant mortality and childhood morbidity. To develop primary prevention approaches to VLBW birth and its sequelae, information is needed on the causes of preterm birth, their personal and social antecedents, and on conditions associated with very low birthweight. Despite the growing body of evidence linking sociodemographic variables with preterm delivery, little is known as to how this may be extrapolated to the risk of very low birthweight.
In 1992, two years after the German unification, we started to recruit two cohorts of very low birthweight infants and controls in East and West Berlin for a long-term neurodevelopmental study. The present analysis was undertaken to compare potential preconceptional risk factors for very low birthweight delivery in a case-control design including 166 mothers (82 East vs. 84 West Berlin) with very low birthweight delivery and 341 control mothers (166 East vs. 175 West).
Multivariate logistic regression analysis was used to assess the effects of various dichotomous parental covariates and their interaction with living in East or West Berlin. After backward variable selection, short maternal school education, maternal unemployment, single-room apartment, smoking, previous preterm delivery, and fetal loss emerged as significant main effect variables, together with living in West Berlin as positive effect modificator for single-mother status.
Very low birthweight has been differentially associated with obstetrical history and indicators of maternal socioeconomic status in East and West Berlin. The ranking of these risk factors is under the influence of the political framework.
PMCID: PMC117217  PMID: 12095425
5.  Patients with preeclampsia develop agonistic autoantibodies against the angiotensin AT1 receptor 
Journal of Clinical Investigation  1999;103(7):945-952.
Immune mechanisms and the renin–angiotensin system are implicated in preeclampsia. We investigated 25 preeclamptic patients and compared them with 12 normotensive pregnant women and 10 pregnant patients with essential hypertension. Antibodies were detected by the chronotropic responses to AT1 receptor–mediated stimulation of cultured neonatal rat cardiomyocytes coupled with receptor-specific antagonists. Immunoglobulin from all preeclamptic patients stimulated the AT1 receptor, whereas immunoglobulin from controls had no effect. The increased autoimmune activity decreased after delivery. Affinity-column purification and anti–human IgG and IgM antibody exposure implicated an IgG antibody directed at the AT1 receptor. Peptides corresponding to sites on the AT1 receptor's second extracellular loop abolished the stimulatory effect. Western blotting with purified patient IgG and a commercially obtained AT1 receptor antibody produced bands of identical molecular weight. Furthermore, confocal microscopy of vascular smooth muscle cells showed colocalization of purified patient IgG and AT1 receptor antibody. The protein kinase C (PKC) inhibitor calphostin C prevented the stimulatory effect. Our results suggest that preeclamptic patients develop stimulatory autoantibodies against the second extracellular AT1 receptor loop. The effect appears to be PKC-mediated. These novel autoantibodies may participate in the angiotensin II–induced vascular lesions in these patients.
PMCID: PMC408252  PMID: 10194466

Results 1-5 (5)