Surfactant administration during endotracheal CPAP: feasibility, risk factors for failure and short-term outcomes of DD-SURF

AIM

Whereas there is agreement, that surfactant should be administered without mechanical ventilation, there is still a debate concerning the optimal method. DD-SURF combines the benefits of INSURE and less invasive surfactant administration (LISA). The efficacy of this approach has not been evaluated yet.

METHODS

Retrospective cohort study of all preterm newborns below 30^0/7 weeks gestational age admitted to the neonatal intensive care unit. Data on surfactant therapy, respiratory support during the first 96 hours of life and neonatal morbidities until hospital discharge were collected from the electronic patient charts to evaluate the efficacy and safety of our approach.

RESULTS

222 newborns met the inclusion criteria. 174 (78%) received surfactant in the delivery room by the DD-SURF procedure. 21 infants (10%) were not extubated after surfactant administration (Surf-and-vent group). 75% of patients after DD-SURF did not require reintubation. Intraventricular hemorrhage and bronchopulmonary dysplasia occured more often in infants after DD-SURF failure than after successful DD-SURF.

CONCLUSION

DD-SURF potentially combines the benefits of INSURE and LISA and represents a useful alternative of surfactant delivery with comparable success rates to thin-catheter surfactant administration.

Measurement of the ν μ energy spectrum with IceCube-79: IceCube Collaboration

IceCube is a neutrino observatory deployed in the glacial ice at the geographic South Pole. The ν μ energy unfolding described in this paper is based on data taken with IceCube in its 79-string configuration. A sample of muon neutrino charged-current interactions with a purity of 99.5% was selected by means of a multivariate classification process based on machine learning. The subsequent unfolding was performed using the software Truee. The resulting spectrum covers an E ν -range of more than four orders of magnitude from 125 GeV to 3.2 PeV. Compared to the Honda atmospheric neutrino flux model, the energy spectrum shows an excess of more than 1.9 σ in four adjacent bins for neutrino energies E ν ≥ 177.8 TeV . The obtained spectrum is fully compatible with previous measurements of the atmospheric neutrino flux and recent IceCube measurements of a flux of high-energy astrophysical neutrinos.

Constraints on Ultrahigh-Energy Cosmic-Ray Sources from a Search for Neutrinos above 10 PeV with IceCube

We report constraints on the sources of ultrahigh-energy cosmic rays (UHECRs) above 10^{9}  GeV, based on an analysis of seven years of IceCube data. This analysis efficiently selects very high- energy neutrino-induced events which have deposited energies from 5×10^{5}  GeV to above 10^{11}  GeV. Two neutrino-induced events with an estimated deposited energy of (2.6±0.3)×10^{6}  GeV, the highest neutrino energy observed so far, and (7.7±2.0)×10^{5}  GeV were detected. The atmospheric background-only hypothesis of detecting these events is rejected at 3.6σ. The hypothesis that the observed events are of cosmogenic origin is also rejected at >99% CL because of the limited deposited energy and the nonobservation of events at higher energy, while their observation is consistent with an astrophysical origin. Our limits on cosmogenic neutrino fluxes disfavor the UHECR sources having a cosmological evolution stronger than the star formation rate, e.g., active galactic nuclei and γ-ray bursts, assuming proton-dominated UHECRs. Constraints on UHECR sources including mixed and heavy UHECR compositions are obtained for models of neutrino production within UHECR sources. Our limit disfavors a significant part of parameter space for active galactic nuclei and new-born pulsar models. These limits on the ultrahigh-energy neutrino flux models are the most stringent to date.

Methylation analysis of the promoter region and intron 1 of the factor VIII gene in haemophilia A patients

Methylation, CpG island, promoter, intron 1 Haemophilia A is the most common X-linked inherited coagulation disorder caused by a deficiency of the factor VIII protein (FVIII). A plethora of different mutations in the factor VIII gene (F8) have been identified as causative for this bleeding disease including a few promoter mutations. However, in approximately 2-5% of all haemophilic patients, the causal mutation still remains unknown. To our knowledge, epigenetic abnormalities in regulatory regions of the F8 gene have not yet been implicated in the disease pathogenesis. We therefore developed bisulfite pyrosequencing assays to screen patients with unknown mutation status for their methylation patterns in presumed regulative regions of the F8 gene (5'UTR and intron 1). The methylation patterns of haemophilia A patients did not differ from that of controls. In three patients, chromosomal aberrations were identified which could be associated with a defective FVIII synthesis.

Methylation analysis of the promoter region and intron 1 of the factor VIII gene in haemophilia A patients

Haemophilia A is the most common X-linked inherited coagulation disorder caused by a deficiency of the factor VIII protein (FVIII). A plethora of different mutations in the factor VIII gene (F8) have been identified as causative for this bleeding disease including a few promoter mutations. However, in approximately 2–5% of all haemophilic patients, the causal mutation still remains unknown. To our knowledge, epigenetic abnormalities in regulatory regions of the F8 gene have not yet been implicated in the disease pathogenesis.

We therefore developed bisulfite pyrosequencing assays to screen patients with unknown mutation status for their methylation patterns in presumed regulative regions of the F8 gene (5’UTR and intron 1). The methylation patterns of haemophilia A patients did not differ from that of controls. In three patients, chromosomal aberrations were identified which could be associated with a defective FVIII synthesis.

Epigenetic profile of developmentally important genes in bovine oocytes

Assisted reproductive technologies are associated with an increased incidence of epigenetic aberrations, specifically in imprinted genes. Here, we used the bovine oocyte as a model to determine putative epigenetic mutations at three imprinted gene loci caused by the type of maturation, either in vitro maturation (IVM) in Tissue Culture Medium 199 (TCM) or modified synthetic oviduct fluid (mSOF) medium, or in vivo maturation. We applied a limiting dilution approach and direct bisulfite sequencing to analyze the methylation profiles of individual alleles (DNA molecules) for H19/IGF2, PEG3, and SNRPN, which are each associated with imprinting defects in humans and/or the mouse model, and are known to be differentially methylated in bovine embryos. Altogether, we obtained the methylation patterns of 203 alleles containing 4,512 CpG sites from immature oocytes, 213 alleles with 4,779 CpG sites from TCM-matured oocytes, 215 alleles/4,725 CpGs in mSOF-matured oocytes, and 78 alleles/1,672 CpGs from in vivo-matured oocytes. The total rate of individual CpGs and entire allele methylation errors did not differ significantly between the two IVM and the in vivo group, indicating that current IVM protocols have no or only marginal effects on these critical epigenetic marks. Furthermore, the mRNA expression profiles of the three imprinted genes and a panel of eight other genes indicative of oocyte competence were determined by quantitative real-time PCR. We found different mRNA expression profiles between in vivo-matured oocytes versus their in vitro-matured counterparts, suggesting an influence on regulatory mechanisms other than DNA methylation.

261 INFLUENCE OF IN VITRO MATURATION ON EPIGENETIC MARKS AND GENE EXPRESSION IN BOVINE OOCYTES

In cattle, in vitro maturation (IVM) of oocytes is an integral part of assisted reproduction technology. However, only 30% of in vitro matured bovine oocytes develop to the blastocyst stage after fertilization (compared with 60% for in vivo matured oocytes), indicating critical involvement of maturation conditions in the developmental competence of oocytes. Oocytes for IVF and intracytoplasmic sperm injection in humans are typically allowed to mature in vivo after superovulation because IVM is not considered to be a safe medical procedure. Several studies have shown that assisted reproduction technology involving prolonged in vitro culture of human and ruminant embryos can be associated with increased risk of fetal or placental abnormalities due to aberrant DNA methylation of imprinted and non-imprinted genes. Similarities between the bovine large offspring syndrome and imprinting-related human Beckwith–Wiedemann syndrome and the general similarity of bovine and human pre-implantation development make bovine oocyte maturation and embryonic development an increasingly accepted model of human development. Differentially methylated regions and imprinting control regions for the bovine paternally imprinted gene H19 and the maternally imprinted genes PEG3 and SNRPN were identified and characterised in this study. The DNA methylation profiles of bovine oocytes could be determined by bisulfite treatment of DNA from pools of 10 oocytes, but no significant differences were observed between IVM in TCM medium with 20% O2, in SOF medium with 5% O2, or after in vivo maturation. In contrast, quantitative PCR analysis of single oocyte preparations (n ≥ 8) revealed significant differences between these groups in the expression of the 3 genes. We then investigated the expression of genes involved in other critical processes in the developing oocyte and early embryo by quantitative PCR, including SLC2A8 (glucose transport), GDF9 (growth factor), PRDX1 (antioxidant and intercellular communication), DNMT1a/b (maintenance of methylation), and DNMT3a/b (de novo methylation). We also studied IGF2R, an imprinted gene implicated in large offspring syndrome. We observed significant differences in the expression of several of these genes. Interestingly, the expression of DNMT3a and DNMT3b was significantly higher in in vitro matured oocytes than in in vivo matured oocytes and could result in the above-mentioned aberrant methylation patterns established later in embryonic development. This work was funded by DFG (FOR1041).

Characterization of differentially methylated regions in 3 bovine imprinted genes: a model for studying human germ-cell and embryo development

Correct imprinting is crucial for normal fetal and placental development in mammals. Experimental evidence in animal models and epidemiological studies in humans suggest that assisted reproductive technologies (ARTs) can interfere with imprinted gene regulation in gametogenesis and early embryogenesis. Bos taurus is an agriculturally important species in which ARTs are commonly employed. Because this species exhibits a similar preimplantation development and gestation length as humans, it is increasingly being used as a model for human germ-cell and embryo development. However, in contrast to humans and mice, there is relatively little information on bovine imprinted genes. Here, we characterized the bovine intergenic IGF2-H19 imprinting control region (ICR) spanning approximately 3 kb. We identified a 300-bp differentially methylated region (DMR) approximately 6 kb upstream of the H19 promoter, containing a CpG island with CTCF-binding site and high sequence similarity with the human intergenic ICR. Additional differentially methylated CpG islands lie -6 kb to -3 kb upstream of the promoter, however these are less conserved. Both classical bisulfite sequencing and bisulfite pyrosequencing demonstrated complete methylation of the IGF2-H19 ICR in sperm, complete demethylation in parthenogenetic embryos having only the female genome, and differential methylation in placental and somatic tissues. In addition, we established pyrosequencing assays for the previously reported bovine SNRPN and PEG3 DMRs. The observed methylation patterns were consistent with genomic imprinting in all analyzed tissues/cell types. The identified IGF2-H19 ICR and the developed quantitative methylation assays may prove useful for further studies on the relationship between ARTs and imprinting defects in the bovine model.

Cross-species chromosome painting corroborates microchromosome fusion during karyotype evolution of birds

The stone curlew, also known as thick-knee (Burhinus oedicnemus, BOE), represents a phylogenetically young species of the shorebirds (Charadriiformes) that exhibits one of the most atypical genome organizations known within the class of Aves, due to an extremely low diploid number (2n = 42) and only 6 pairs of microchromosomes in its complement. This distinct deviation from the 'typical' avian karyotype is attributed to repeated fusions of ancestral microchromosomes. In order to compare different species with this atypical avian karyotype and to investigate the chromosome rearrangement patterns, chromosome-specific painting probes representing the whole genome of the stone curlew were used to delineate chromosome homology between BOE and 5 species belonging to 5 different avian orders: herring gull (Charadriiformes), cockatiel (Psittaciformes), rock pigeon (Columbiformes), great gray owl (Strigiformes) and Eurasian coot (Gruiformes). Paints derived from the 20 BOE autosomes delimited 28 to 33 evolutionarily conserved segments in the karyotypes of the 5 species, similar to the number recognized by BOE paints in such a basal lineage as the chicken (28 conserved segments). This suggests a high degree of conservation in genome organization in birds. BOE paints also revealed some species-specific rearrangements. In particular, chromosomes BOE1-4 and 14, as well as to a large extent BOE5 and 6, showed conserved synteny with macrochromosomes, whereas homologous regions for BOE7-13 are found to be largely distributed on microchromosomes in the species investigated. Interestingly, the 6 pairs of BOE microchromosomes 15-20 appear to have undergone very few rearrangements in the 5 lineages investigated. Although the arrangements of BOE homologous segments on some chromosomes can be explained by complex fusions and inversions, the occurrence of homologous regions at multiple sites may point to fission of ancestral chromosomes in the karyotypes of the species investigated. However, the present results demonstrate that the ancestral microchromosomes most likely experienced fusion in the stone curlew lineage forming the medium-sized BOE chromosomes, while they have been conserved as microchromosomes in the other neoavian lineages.

340 EPIGENETIC ANALYSIS OF DEVELOPMENTALLY IMPORTANT GENES IN BOVINE OOCYTES OF DIFFERENT ORIGINS

A critical step in assisted reproductive technologies (ART) is the IVM of oocytes. The quality of the oocyte is crucial for successful fertilization and subsequent embryo development. Studies in bovine ART, and epidemiological studies in children from ART, reveal a degree of abnormal development thought to be primarily caused by aberrant DNA methylation patterns in imprinted and non-imprinted genes. Due to the inherent similarities in bovine and human preimplantation embryonic development, bovine oocyte and embryo development is increasingly being used as a model for human development. The goal of this project is to investigate the effects of specific IVM conditions on the DNA methylation profile of bovine oocytes and early embryos and to determine the relationship between DNA methylation and mRNA expression for selected developmentally important genes (PEG3, IGF2R, SNRPN, GDF9, Glut8, PRDX1, Dnmt1A and Dnmt3a/b). Two different IVM systems have been established, the first is the routinely used TCM-199 medium at 39°C, 5% CO2 in air, the second uses synthetic oviduct fluid medium (SOF) as the basic medium with minor modifications (10 mM glucose, 1 mM glutamine) at 39°C, 5% CO2 and reduced oxygen tension (5%). Oocytes for IVM were retrieved by slicing of ovaries collected from local slaughterhouses. Successful maturation was confirmed by extrusion of the first polar body for 78% (TCM) and 72% (SOF) of the oocytes, respectively. Results of quantitative real-time PCR experiments indicate that transcripts of the maternally imprinted gene PEG3 and the paternally imprinted gene IGF2R as well as transcripts of other developmentally important genes (GDF9, PRDX1 and Glut8) are present in immature and IVM oocytes and are applicable targets for further expression and methylation studies. Relative quantification of mRNA transcripts normalised to an external standard revealed that, while expression of the maternally imprinted PEG3 gene is lower in all groups of oocytes (immature: 9.8, matured in TCM: 3.3, and in SOF: 6.4), compared to the paternally imprinted IGF2R (immature: 29.3, TCM: 14.2, SOF: 19.2), no significant difference between the both groups of IVM oocytes could be detected. However, determination of specific effects of IVM will require more replicates and the comparison with IVM oocytes. This is currently underway and together with the ongoing methylation analysis based on the novel identification of differentially methylated regions in bovine imprinted genes, this study will provide deeper insight into the epigenetic profile of bovine oocytes as a potential causative mechanism implicated in the increased incidence of developmental abnormalities in human and bovine ART. Funded by DFG Research Unit Germ Cell Potential.