Biomedical subjects

Sevgi Tercanli

Publications and source records attributed to Sevgi Tercanli.

6 recordsLinked to original sources

PubMed2005

Cell-free foetal DNA in maternal plasma does not appear to be derived from the rich pool of cell-free foetal DNA in amniotic fluid.

BACKGROUND: Large quantities of cell-free foetal DNA have been detected in amniotic fluid, and it has been proposed that this material may contribute to the pool of cell-free foetal DNA in maternal plasma. METHODS: Twelve maternal blood samples were obtained from pregnant women about to undergo an amniocentesis. Cell-free DNA was extracted from the maternal plasma samples and the matched amniotic fluid samples. The amount of cell-free foetal DNA was quantified by real-time PCR assays for the SRY and RHD genes. RESULTS: Amniotic fluid was found to contain vast quantities of cell-free DNA (median concentration = 3,978 copies/ml amniotic fluid). The concentration of cell-free foetal DNA in maternal plasma was much lower (median concentration = 96.6 copies/ml maternal plasma). No significant correlation could, however, be determined between these two pools of cell-free foetal DNA. CONCLUSIONS: Our data confirm that amniotic fluid contains prodigious quantities of cell-free foetal DNA, but as no relationship exists between this material and that in the maternal circulation, it is unlikely that the amnion contributes to the presence of cell-free foetal DNA in maternal plasma.

Amniotic Fluid↗

PubMed2005

Numerous erythroblasts in maternal blood are impervious to fluorescent in situ hybridization analysis, a feature related to a dense compact nucleus with apoptotic character.

BACKGROUND AND OBJECTIVES: The analysis by fluorescence in situ hybridization (FISH) of fetal erythroblasts enriched from maternal blood remains an attractive alternative for risk-free prenatal diagnosis of aneuploidies. However, current results are discouraging because of the low levels of sensitivity or the inability to detect fetal erythroblasts by FISH. DESIGN AND METHODS: Erythroblasts were enriched from 35 maternal blood samples by magnetic cell sorting (MACS), identified morphologically following May-Grünwald Giemsa staining and examined by FISH for chromosomes X, Y and 18. RESULTS: We observed that circulating erythroblasts comprised two distinct groups: one was clearly of maternal origin and could be reliably analyzed by FISH, whereas the other, which appeared to be of fetal origin, was largely impervious to FISH analysis. This latter feature seemed to be related to an abnormally dense nucleus with an apoptotic character. Since the oxygen tension in the maternal circulation is higher than that in the fetus, we cultured fetal cord blood erythroblasts in conditions mimicking this difference in oxygen concentrations and found that high oxygen concentrations rapidly induced shrinkage of the erythroblast nucleus, rendering it impervious to FISH analysis. INTERPRETATION AND CONCLUSIONS: Our data show that circulating erythroblasts of presumed fetal origin cannot be reliably analyzed by FISH because of an abnormally dense nucleus. This nuclear phenotype appears to be induced by the higher oxygen tension present in the maternal circulation than in fetal blood.

Aneuploidy↗

PubMed2003

Sirenomelia, the mermaid syndrome--detection in the first trimester.

The sirenomelia sequence with fusion, rotation, hypotrophy or atrophy of the lower limbs in combination with severe urogenital and gastrointestinal malformations is a rare and usually lethal disorder. We present the case of a 28-year-old woman, who was referred to our department because of an intraabdominal cystic structure in the 9th week of gestation. Subsequent scans confirmed the diagnosis of a sirenomelia sequence with the fusion of the lower extremities without fusion of the bones according to Stocker I classification. The size of the intraabdominal cyst decreased during follow-up. After counseling, termination of pregnancy was induced. The postmortem X-ray confirmed the ultrasound diagnosis. The exact etiological mechanism of this malformation is still unknown. An early alteration of the embryological vascular network damaging the caudal mesoderm is thought to lead to arrested development of the lower limbs and other affected organs. The cyst we saw in the 9th week might fit with this theory, either as an expression of the complex malformation of the lower abdomen or as the sonographic appearance of necrosis.

Abortion, Eugenic↗

PubMed2003

Cervical length assessment by ultrasound as a predictor of preterm labour--is there a role for routine screening?

Transvaginal ultrasonography has recently been shown to be an objective, reproducible and reliable method to assess the cervix and predict the risk of preterm delivery in high-risk pregnancies. Assessment of the cervix includes cervical length measurement (CLM) and measurement of dilatation of the internal os in a dynamic functional examination. There is an inverse correlation between cervical length and the frequency of preterm delivery. The high negative predictive value avoids unnecessary interventions such as tocolysis or cerclage in high-risk pregnancies. In contrast, a length of 25 mm or less at 28-30 weeks of gestation is associated with a significantly increased incidence of preterm delivery. Studies in women with high risk for preterm delivery, i.e. contractions, premature rupture of the membranes and history of preterm delivery, have shown a high sensitivity and a high positive predictive value, however in low-risk groups they have failed to show a high sensitivity. From large observational studies in low-risk populations we know that the 50th percentile of the cervical length is 35 mm at 24 weeks of gestation. Advantages of CLM as a screening test include the fact that sonographical assessment of the cervix is a widely accepted and well-standardised method, which requires only a relatively short period of training. Disadvantages of screening are two factors, the first being the low sensitivity of the test and the low prevalence of preterm deliveries in a low-risk population, resulting in cut off values being set at a very low level (i.e. 5th percentile) in order to get acceptable specificity. Secondly, screening is only worthwhile if an effective preventive therapy is available. The debate about tocolysis and cerclage is not yet concluded. Therefore we would not currently recommend cervical length measurement as a screening tool-but as a routine method in high risk gravidas with or without symptoms. Further interest should be focused on scoring systems combining ultrasound with biochemical, endocrinological and maybe molecular cell methods such as the measurement of fetal DNA in maternal blood to prevent preterm deliveries in the general population.

Cervix Uteri↗

PubMed2002

Developments in laboratory techniques for prenatal diagnosis.

Ongoing trends in prenatal diagnosis aim at early, rapid, and ideally noninvasive diagnosis as well as at the improvement of risk-screening for aneuploidy. Interphase-fluorescence in situ hybridization and quantitative fluorescence polymerase chain reaction are efficient tools for the rapid exclusion of selected aneuploidies in addition to the established direct preparation of chromosomes from chorionic villi. Interphase fluorescence in situ hybridization has also made possible the diagnosis of selected chromosome abnormalities in single cells (e.g. in preimplantation genetic diagnosis) or noninvasive diagnosis. More complex multicolor fluorescence in situ hybridization approaches are currently being evaluated. Single cell polymerase chain reaction is the key technique for the molecular diagnosis of a growing number of monogenic conditions before implantation or, still more experimental, in fetal cells retrieved from the maternal circulation. New sources for noninvasive diagnosis came into play such as fetal DNA or cell nuclei in maternal plasma. The combination of biochemical parameters in the maternal serum, namely free beta-human chorionic gonadotropin with pregnancy associated plasma protein A and sonographic markers, has already dramatically increased the sensitivity of risk screening in the first trimester of pregnancy.

Amniocentesis↗

PubMedDate not supplied

Influence of volume preloading on uteroplacental and fetal circulation during spinal anaesthesia for caesarean section in uncomplicated singleton pregnancies.

OBJECTIVE: Effects of volume preloading during spinal anaesthesia for elective caesarean section on maternal blood pressure, feto-maternal circulation and fetal outcome. PATIENTS AND METHODS: In a pilot study a randomised trial was performed in 22 healthy women with uncomplicated, singleton pregnancies at 36-40 weeks of gestation undergoing elective caesarean section under spinal anaesthesia. In the low volume group (group A) patients received 150 ml of crystalloid solution for preloading, in the high volume group (group B) they were given 15 ml/kg of crystalloid solution for preloading before the initiation of spinal anaesthesia. Maternal blood pressure was monitored intermittently. Hypotension was defined as a decrease in systolic pressure to less than 80% of the baseline value. The Doppler flow evaluation consisted of measurements from the uterine artery at the placental site, fetal umbilical artery and fetal middle cerebral artery. Pulsatility indices were derived before and after fluid preloading, and when spinal anaesthesia was established. The neonatal outcome was assessed by Apgar scores, arterial acid base status and neurologic and adaptive capacity scores (NACS). RESULTS: The incidence of maternal hypotension in both groups was 45.5% (n = 10); 3 cases occurred in group A compared to 7 cases in group B (n.s.). There was no evidence that the high dose volume is useful in preventing maternal hypotension. The pulsatility indices of uterine arteries, umbilical arteries and middle cerebral arteries were not altered. Statistical analysis showed no changes in neonatal outcome concerning umbilical arterial pH, Apgar score and NACS (n.s.) between groups A and B. CONCLUSIONS: Our preliminary results suggest that high dose crystalloid volume preloading has no preventive function in the avoidance of maternal hypotension in healthy parturients undergoing elective caesarean section under spinal anaesthesia, and shows no harmful effects on neonatal outcome as long as maternal hypotension is corrected immediately. However, the statistical significance may reflect the small sample size, and larger series are needed before changing the current management.

Anesthesia, Spinal↗