The effect of a sonographic estimated fetal weight on the risk of cesarean delivery in macrosomic and small for gestational-age infants*

Objective: To assess the association of a sonographic estimated fetal weight (sonoEFW) with the risk of cesarean delivery in women with macrosomic or small for gestational age (SGA) infants.

Methods: Retrospective cohort of singleton deliveries >24 weeks by one MFM practice from 2005 to 2014. We included all patients who delivered an infant with macrosomia (birth weight ≥4000?g) or SGA (birth weight <10th percentile). We compared the risk of cesarean delivery between patients who did and did not have a sonoEFW within four weeks of delivery. Regression analysis was performed to control for any differences in baseline characteristics.

Results: In patients with macrosomic infants (n?=?352), the risk of cesarean delivery was significantly higher in the sonoEFW group (45.3% versus 17.6%, aOR 2.144, 95% CI: 1.06–4.34). When we restricted the analysis to the subgroup of 265 patients who attempted vaginal delivery, our results were similar (22.3% versus 9.1%, aOR 2.73, 95% CI: 1.15–6.48). In patients with an SGA infant (n?=?614), the risk of cesarean delivery was not higher in the sonoEFW group (37.4% versus 24.1%, aOR 1.23, 95% CI: 0.80–2.07), nor in those who attempted vaginal delivery (19.8% versus 13.7%, aOR 1.17, 95% CI: 0.62–2.21).

Conclusions: A sonoEFW prior to delivery is independently associated with cesarean delivery in women with macrosomic infants, but not those with SGA infants. This should be considered when deciding to obtain a sonoEFW at the end of pregnancy, particularly if not for an accepted indication.     

NMDA receptors regulate developmental gap junction uncoupling via CREB signaling

Signaling through gap junctions (electrical synapses) is important in the development of the mammalian central nervous system. Abundant between neurons during postnatal development, gap junction coupling subsequently decreases and remains low in the adult, confined to specific subsets of neurons. Here we report that developmental uncoupling of gap junctions in the rat hypothalamus in vivo and in vitro is associated with a decrease in connexin 36 (Cx36) protein expression. Both developmental gap junction uncoupling and Cx36 downregulation are prevented by the blockade of NMDA glutamate receptors, action potentials and the calcium-cyclic AMP response element binding protein (CREB), and are accelerated by CREB overexpression. Developmental gap junction uncoupling and Cx36 downregulation are not affected by blockade of non-NMDA glutamate receptors, and do not occur in hypothalamic neurons from NMDA receptor subunit 1 (NMDAR1) knockout mice. These results demonstrate that NMDA receptor activity contributes to the developmental uncoupling of gap junctions via CREB-dependent downregulation of Cx36.     

The association between maternal height and pregnancy outcomes in twin gestations

Objective: We sought to assess the association between maternal height and the risk of preterm birth, fetal growth restriction and mode of delivery in twin gestations.

Study design: Cohort study of patients with twin pregnancies delivered from 2005 to 2014. We compared pregnancy outcomes between patients of short stature?≤159?cm to those of normal stature?≥160?cm. Patients with monoamniotic twins and major fetal anomalies were excluded. Pearson’s correlation, Chi-square and Student’s t-test were used as appropriate.

Results: Six hundred and sixty-six patients were included, 159 (23.9%) of whom had short stature (mean height 155.8?±?2.5?cm) and 507 (76.1%) of whom had normal stature (mean height 167.2?±?5.5?cm). There were no differences in outcomes between the groups in regards to preterm birth, gestational age (GA) at delivery, birth weight of either twin, preeclampsia, gestational diabetes or cesarean section rate. Results were similar when the groups were stratified by parity. As a continuous variable, maternal height did not correlate with GA at delivery (p=?0.388), cesarean delivery (p?=?0.522) nor the birth weight of the larger (p?=?0.206) or smaller (p?=?0.307) twin.

Conclusion: In twin pregnancies, maternal short stature is not associated with preterm birth, fetal growth restriction or cesarean section rate. This suggests that although anthropometric measurements have long been used to counsel patients in regards to outcomes, patients of short stature should be reassured that their height does not appear to lead to adverse twin pregnancy outcomes.     

Self-organized nanotubular oxide layers on Ti-6Al-7Nb and Ti-6Al-4V formed by anodization in NH4F solutions

The present work reports the fabrication of self-organized porous oxide-nanotube layers on the biomedical titanium alloys Ti-6Al-7Nb and Ti-6Al-4V by a simple electrochemical treatment. These two-phase alloys were anodized in 1M (NH(4))(2)SO(4) electrolytes containing 0.5 wt % of NH(4)F. The results show that under specific anodization conditions self-organized porous oxide structures can be grown on the alloy surface. SEM images revealed that the porous layers consist of arrays of single nanotubes with a diameter of 100 nm and a spacing of 150 nm. For the V-containing alloy enhanced etching of the beta phase is observed, leading to selective dissolution and an inhomogeneous pore formation. For the Nb-containing alloy an almost ideal coverage of both phases is obtained. According to XPS measurements the tubes are a mixed oxide with an almost stoichiometric oxide composition, and can be grown to thicknesses of several hundreds of nanometers. These findings represent a simple surface treatment for Ti alloys that has high potential for biomedical applications.     

Wiener kernels of chinchilla auditory-nerve fibers: verification using responses to tones, clicks, and noise and comparison with basilar-membrane vibrations

Responses to tones, clicks, and noise were recorded from chinchilla auditory-nerve fibers (ANFs). The responses to noise were analyzed by computing the zeroth-, first-, and second-order Wiener kernels (h0, h1, and h2). The h1s correctly predicted the frequency tuning and phases of responses to tones of ANFs with low characteristic frequency (CF). The h2s correctly predicted the frequency tuning and phases of responses to tones of all ANFs, regardless of CF. Also regardless of CF, the kernels jointly predicted about 77% of the features of ANF responses to "frozen" samples of noise. Near-CF group delays of kernels and signal-front delays of responses to intense rarefaction clicks exceeded by 1 ms the corresponding basilar-membrane delays at both apical and basal sites of the chinchilla cochlea. This result, confirming that synaptic and neural processes amount to 1 ms regardless of CF, permitted drawing a map of basilar-membrane delay as a function of position for the entire length of the chinchilla cochlea, a first for amniotic species.     

Nature of telomere dimers and chromosome looping in human spermatozoa

Specific and well-organized chromosome architecture in human sperm cells is supported by the prominent interactions between centromeres and between telomeres. The telomere-telomere interactions result in telomere dimers that are positioned at the nuclear periphery. It is unknown whether composition of sperm telomere dimers is random or specific. We now report that telomere dimers result from specific interactions between the two ends of each chromosome. FISH using pairs of subtelomeric DNA probes that correspond to the small and long arms of seven human chromosomes demonstrates that subtelomeres of one chromosome are brought together. Statistical analysis confirmed that telomere associations could not result from the random proximity of DNA sequences. Therefore, chromosomes in human sperm nuclei adopt a looped conformation. This higher-order chromosome structure is most likely required for chromosome withdrawal/decondensation during the early fertilization events leading to zygote formation. These individuals contributed equally to the work     

The molecular structure of the DNA fragments eliminated during chromatin diminution in Cyclops kolensis

Presumptive somatic cells of the copepod Cyclops kolensis specifically eliminate a large fraction of their genome by the process of chromatin diminution. The eliminated DNA (eDNA) remains only in the germline cells. Very little is known about the nature of the sequences eliminated from somatic cells. We cloned a fraction of the eDNA and sequenced 90 clones that total 32 kb. The following organizational patterns were demonstrated for the eDNA sequences. All do not contain open reading frames. Each fragment contains 1-3 families of short repeats (10-30 bp) highly homologous within families (87%-100%). Most repeats are separated by spacers up to 50 bp long. Homologous regions were found between fragments, motifs from 15-300 bp in length. Among fragments there occur groups in which the same motifs are ordered in the same fashion. However, spacers between the motifs differ in length and nucleotide composition. Ubiquitous motifs (those occurring in all fragments) were identified. Analysis of motifs revealed submotifs, each occurring within several motifs. Thus, motifs may be regarded as mosaic structures composed of submotifs (short repeats). Taken together, the results provide evidence of a high organizational ordering of the DNA sequences restricted to the germline. With this in mind, it appears incorrect to refer to this part of the genome as junk. Moreover, eDNA is redundant for only the somatic cells-its function is to be sought in germline cells.     

First identification of Neospora caninum by PCR in aborted bovine foetuses in Romania

The first identification of Neospora caninum infection in aborted bovine foetuses in Romania is reported. Nine aborted foetuses were collected from a dairy farm. The foetal age of foetuses was between 3 and 7 months. A 7-month-old foetus was mummified. N. caninum DNA Nc-5 region was amplified from samples extracted from brain tissues of three (33.3%) aborted foetuses. The foetal ages of PCR positive foetuses were 3, 4 and 7 months (mummified). No specific lesions or tissue cysts were found to the histological examination, because of advanced autolysis of brains.