Publications by authors named "Steven J McArthur"

High-speed atomic force microscopy (HS-AFM) is a unique approach that allows direct real-time visualization of biological macromolecules in action under near-physiological conditions, without any chemical labeling. Typically, the temporal resolution is sub-100 ms, and the spatial resolution is 2-3 nm in the lateral direction and ∼0.1 nm in the vertical direction.

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Purpose: Does re-biopsy of blastocysts classified as abnormal (ABN) due to segmental aneuploidy (SA) have clinical utility?

Methods: The live birth (LB) outcomes of mosaic SAs, compared to other categories, were determined after transfer of 3084 PGT-A tested blastocysts. An initial 12-month trial thawed 111 blastocysts classified as ABN due to a SA for clinical re-biopsy, with an additional 58 from a subsequent 16-month revised protocol. Where re-biopsy failed to corroborate the original classification, blastocysts were reported as mosaic and suitable for clinical use.

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Results: In 221 cycles from 138 patients (104 cycles requiring HLA matching), 90.5% had embryo(s) biopsied for genetic testing. There were 119 embryo transfers for thalassemia (76) and thalassemia-HLA cases (43), respectively, resulting in overall clinical pregnancy rates of 54.

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Objective: To assess the impact of multiple blastocyst biopsy and vitrification-warming procedures on clinical outcomes.

Design: Retrospective study.

Setting: Private fertility clinic.

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Hijacking of cellular biosynthetic pathways by human enveloped viruses is a shared molecular event essential for the viral lifecycle. In this study, the accumulating evidence of the importance of human glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in the host secretory pathway led us to hypothesize that this moonlighting enzyme could play a key role in the lifecycle steps of two important Flaviviridae members, hepatitis C virus (HCV) and dengue virus (DENV). We used short interfering RNA (siRNA)-mediated knockdown of human GAPDH in Huh-7.

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In assisted reproduction, embryos derived from monopronucleated (1PN) zygotes are considered abnormal and unsuitable for clinical use. Outcomes of 1PN-derived embryos designated for preimplantation genetic screening (PGS) were analysed. These embryos, especially from intracytoplasmic sperm injection (ICSI), were found to have a low developmental potential; 1PN and 2PN day 5 blastocyst development for IVF was 14.

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Viral hijacking and manipulation of host-cell biosynthetic pathways by human enveloped viruses are shared molecular events essential for the viral lifecycle. For Flaviviridae members such as hepatitis C virus and dengue virus (DENV), one of the key subsets of cellular pathways that undergo manipulation is the lipid metabolic pathways, underlining the importance of cellular lipids and, in particular, lipid droplets (LDs) in viral infection. Here, we hypothesize that targeting cellular enzymes that act as key regulators of lipid homeostasis and LD formation could represent a powerful approach to developing a novel class of broad-spectrum antivirals against infection associated with all DENV serotypes (1-4) circulating around the world.

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Purpose: Anti-Müllerian hormone (AMH) is used as a marker for ovarian reserve. Since 2011, the standard test for AMH has been the Beckman Coulter Generation (Gen) II assay. However, in July 2013, the protocol was revised due to falsely low readings.

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Study Question: Can the equilibration steps prior to embryo vitrification be automated?

Summary Answer: We have developed the 'Gavi' system which automatically performs equilibration steps before closed system vitrification on up to four embryos at a time and gives in vitro outcomes equivalent to the manual Cryotop method.

What Is Known Already: Embryo cryopreservation is an essential component of a successful assisted reproduction clinic, with vitrification providing excellent embryo survival and pregnancy outcomes. However, vitrification is a manual, labour-intensive and highly skilled procedure, and results can vary between embryologists and clinics.

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Objective: To compare pregnancy and neonatal outcomes after fresh and vitrified-warmed single-blastocyst transfers.

Design: Retrospective study.

Setting: Private in vitro fertilization (IVF) clinic.

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Blastocysts more commonly have a normal karyotype than cleavage-stage embryos do. Moreover, blastocysts have also made a metabolic transition from catabolism and recycling of the oocyte's reserves and resources, processes that fuel the first 3 days of cleavage. Although not all blastocysts are karyotypically equal, it is still to be determined to what extent a mosaic karyotype might be a normal feature among embryos, both at the cleavage stage and the blastocyst stage--and when looking for karyotypic abnormalities by embryo biopsy might help the chance of implantation rather than harm it.

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Objective: To compare multiple-cell trophectoderm biopsy for preimplantation genetic diagnosis (PGD) from day-5 blastocysts with previously published experience with day-3 cleavage-stage embryos.

Design: Retrospective review of laboratory and clinical experience.

Setting: Sydney IVF, a private clinic in Australia.

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