1,583 research outputs found
Amnio-exchange for gastroschisis does not help, and may even harm
This is a mini commentary on D Luton et al., pp. 1233–1241 in this issue. To view this article visit https://doi.org/10.1111/1471-0528.15804
Synthesis, Structural Studies and Aerosol-Assisted Chemical Vapour Deposition of Precursors towards Zinc Chalcogenides
This work is concerned with the design, synthesis, isolation and subsequent aerosolassisted
chemical vapour deposition (AACVD) of precursors towards the zinc
chalcogenide materials: zinc oxide (ZnO) and zinc oxysulfide (Zn(O,S)). Throughout this
thesis, emphasis is placed on elucidating the relationship between the molecular
structure of the precursor and the functional properties of the resultant material.
Chapter 3 explores this relationship for a series of six precursors bearing !-ketoimine
and !-aminoenoate ligands towards ZnO thin films via AACVD. The deposition of ZnO
thin films has been an area of interest in the materials chemistry community due to its
importance as a semiconductor in optoelectronic devices. Thin film quality is of
paramount importance in these applications and as such, precursor design remains a
research priority.
Chapter 4 describes the synthesis and characterisation of a family of heteroleptic zinc
thioureide complexes with a view to application as single source precursors for the
AACVD of Zn(O,S), as well as being interesting synthetic targets in their own right. The
scarcity of reports of the AACVD of Zn(O,S) via a single source precursor in the literature
to date may not just be due to the fact that this is an emerging material, but also due to
the lack of a suitable precursor.
Chapter 5 explores the combinatorial analysis of Zn(O,S) films in order to better
understand the effects of intermediate compositions on the optoelectronic properties of
the material. The analysis of films from both commercially available precursors and a
novel precursor is undertaken and in the latter case, emphasis is placed on the molecular
properties of the precursor and the effect this has on the deposited Zn(O,S) films
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Focus on Prenatal Detection of Micrognathia
Fetal micrognathia involves abnormal or arrested development of the fetal mandible. Till recently, the prenatal diagnosis was subjective, based on the evaluation of the fetal profile and assessment of the relationship between the maxilla and the mandible. Recently objective sonographic methods have been utilized for diagnosing micrognathia such as the inferior facial angle, the jaw index, the frontal nasomental angle, the mandible width/maxilla width ratio and the mandibular length. Another useful sonographic sign, the mandibular gap in the retronasal triangle view, increases the accuracy of the diagnosis early in the first trimester. 3D sonographic views can add to the diagnosis and prenatal MRI is a useful adjunct to ultrasound in cases of limited acoustic window, maternal obesity, oligohydramnios and anterior spine position. The identification of micrognathia should prompt karyotyping and sonographic investigation for other abnormalities. The outcome of fetuses with this seemingly isolated finding is more guarded than one would intuitively believe, and the parents should be counseled accordingly. Postnatal complications including mild to severe upper airway obstruction leading to respiratory distress, feeding difficulties and mild to severe long-term developmental delay are common. One should be careful in pronouncing a fetus having ‘micrognathia’, especially on subjective evaluation, as this term implies that the fetus is abnormal with presence of significant pathology. There is no ‘gold standard’ for a definitive diagnosis of micrognathia on post-natal evaluation. Using a combination of objective sonographic markers as well as follow-up ultrasound assessments can significantly reduce the risk of a false diagnosis. Follow-up scans should be arranged, and neonatal service should be alerted in cases of ongoing pregnancies
Prenatal Diagnosis of WAGR Syndrome.
Wilm's tumour, aniridia, genitourinary abnormalities, and mental retardation (WAGR) syndrome is a rare genetic disorder with an estimated prevalence of 1 in 500,000 to 1 million. It is a contiguous gene syndrome due to deletion at chromosome 11p13 in a region containing WT1 and PAX6 genes. Children with WAGR syndrome mostly present in the newborn/infancy period with sporadic aniridia. The genotypic defects in WAGR syndrome have been well established. However, antenatal ultrasonographic presentation of this syndrome has never been reported. Prenatal diagnosis of this condition is possible in some cases with careful ultrasound examination of classical and nonclassical manifestations of this syndrome. The key point for this rare diagnosis was the decision to perform chromosomal microarray analysis after antenatal diagnosis of absent corpus callosum and absent cavum septum pellucidum, as this finding mandates search for potentially associated genetic disorders. We report a case of WAGR syndrome diagnosed prenatally at 29-week gestation. The diagnosis of the anomaly was based on two- and three-dimensional ultrasound as well as fetal MRI scan and microarray analysis. The ultrasonographic findings included borderline ventriculomegaly, absent corpus callosum, and absent cavum septum pellucidum. Cytogenetic results from the amniotic fluid confirmed WAGR syndrome. Parental karyotype was normal, with no evidence of copy number change, deletion, or rearrangement of this region of chromosome 11
A simplified guide to randomized controlled trials.
A randomized controlled trial (RCT) is a prospective, comparative, quantitative study/experiment performed under controlled conditions with random allocation of interventions to comparison groups. The RCT is the most rigorous and robust research method of determining whether a cause-effect relationship exists between an intervention and an outcome. High quality evidence can be generated by performing an RCT when evaluating the effectiveness and safety of an intervention. Furthermore, RCTs yield themselves well to systematic review and meta-analysis providing a solid base for synthesizing evidence generated by such studies. Evidence-based clinical practice improves patient outcomes, safety, and is generally cost-effective. Therefore, RCTs are becoming increasingly popular in all areas of clinical medicine including perinatology. However, designing and conducting an RCT, analyzing data, interpreting findings and disseminating results can be challenging as there are several practicalities to be considered. In this review, we provide a simple descriptive guidance on planning, conducting, analyzing and reporting RCTs
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Routine screening for placenta accreta spectrum.
Screening for clinically significant placenta accreta spectrum (PAS) is possible with a high degree of accuracy (both sensitivity and specificity >90-95%). The group of women to focus on are those with placenta previa and one or more prior Cesarean deliveries. Screening for PAS not associated with placenta previa is not as productive, and several false negatives have been described. The results of the screening program indicate that women have a low or high probability of PAS. Screen-positive women or those with uncertain ultrasound features should be referred to a center of excellence. Those confirmed to have a high probability of PAS should electively be delivered at such centers
Morbid adherence of the placenta: lack of specificity should remind us that ultrasound is a screening tool.
Excellent performance has been reported with prenatal diagnosis of abnormal placental invasion using ultrasound. We describe a case which illustrates the validity of ultrasound features of abnormally invasive placentation in women without previous caesarean delivery. CASE: Ms. CB, a 27 year-old G3 P1+1 was seen in her pregnancy at 36 weeks of gestation. Her first pregnancy was uncomplicated and she gave vaginal birth to a normally grown baby at term. Before the current pregnancy, she suffered a miscarriage in the first trimester, and underwent surgical evacuation. She suffered prolonged vaginal blood loss for which she was investigated, and a diagnosis of A-V malformation (AVM) was made on the basis of the ultrasound findings (Figure 1). She conceived spontaneously before intervention
Peyer's Patches Are Precocious to the Appendix in Human Development
PP are first visible at ∼15.5 wk gestation after which there is a rapid spurt in the development
and maturation of lymphoid follicles so that at any given point of time new foci of PP development
are continuously formed at a rapid rate. Addition of rows of follicles results in the
formation of a PP. Immature PP of younger fetuses have a spongy structure in contrast with
the compact lymphoid follicles of mature PP of older fetuses. Immunocytochemical studies
reveal that there is a subtle gradation in the expression of lymphocyte surface markers with
increasing fetal age. Expression of antigenic markers occurs in an ordered sequence viz. HLA – DR, CD19 (B cell population), CD9 (pre-B cells), CD3 T lymphocytes, CD4 helper / inducer lymphocytes, the CD8 suppressor / cytotoxic cells and lastly, the CD57 Natural Killer cells. The antigens are expressed first on lymphocytes of PP and thereafter in those of the appendix. Our findings clearly demonstrate that the
∼5 wk fetal period from 17.5 wk to 22 wk
represents a major growth phase in the development of surface markers of lymphocytes in the
mucosal immune system of the gut
The Association Between Hypertension in Pregnancy and Preterm Birth with Fetal Growth Restriction in Singleton and Twin Pregnancy: Use of Twin Versus Singleton Charts.
OBJECTIVE: To compare the rates of fetal growth restriction (FGR) in singleton and twin pregnancies using singleton and twin-specific birthweight standards. METHODS: The study included liveborn twin and singleton pregnancies between January 2000 and January 2019. Hypertensive disorders of pregnancy (HDP) included gestational hypertension and pre-eclampsia. The study outcomes were FGR or small-for-gestational-age (SGA) at birth as assessed using singleton and twin reference charts. RESULTS: The analysis included 1473 twin and 62,432 singleton pregnancies. In singleton pregnancies the risk of PTB <34 weeks without HDP (OR 2.82, p < 0.001), delivery ≥34 weeks with HDP (OR 2.38, p < 0.001), and PTB <34 weeks with HDP (OR 13.65, p < 0.001) were significantly higher in the pregnancies complicated by FGR compared to those without. When selective fetal growth restriction (sFGR) was assessed using the singleton standard, the risk of PTB <34 weeks without HDP (OR 1.03, p = 0.872), delivery ≥34 weeks with HDP (OR 1.36, p = 0.160) were similar in the pregnancies complicated by sFGR compared to those without, while the risk of PTB <34 weeks with HDP (OR 2.41, p = 0.025) was significantly higher in the pregnancies complicated by sFGR compared to those without. When sFGR was assessed using the twin-specific chart, the risk of PTB <34 weeks without HDP (OR 3.55, p < 0.001), delivery ≥34 weeks with HDP (OR 3.17, p = 0.004), and PTB <34 weeks with HDP (OR 5.69, p < 0.001) were significantly higher in the pregnancies complicated by sFGR compared to those without. The stronger and more consistent association persisted in the subgroup analyses according to chorionicity. The strength of association in dichorionic twin pregnancies resembles that of the singletons more closely and consistently when the FGR was diagnosed using the twin-specific charts. CONCLUSION: FGR in twin pregnancies has a stronger and more consistent association with HDP and PTB when using twin-specific rather than singleton charts. This study provides further evidence supporting the use of twin-specific charts when assessing fetal growth in twin pregnancies
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