No abstract

Groups of amino acids, and some selected amino acids, added to media used for culture of pre-implantation embryos have previously been shown to improve development in various ways including survival to the blastocyst stage, increased blastocyst cell number and improved hatching. In this study, we cultured 1-cell mouse embryos for 5 days to the hatching blastocyst stage in isosmotic medium (270 mOsm/kg) at high density (10 embryos/10 µL), where autocrine/paracrine support of development occurs, and low density (1 embryo/100 µL), where autocrine/paracrine support is minimized and development is compromised. When 400 µM L-Pro or 1 mM L-Gln was added to embryos at low density, the percentage of embryos reaching the blastocyst stage and the percentage hatching increased compared to low-density culture without these amino acids, and were now similar to those for embryos cultured at high density without amino acids. When L-Pro or L-Gln was added to embryos at high density, the percentage of embryos reaching the blastocyst stage didn't change but hatching improved. Neither embryo culture density nor the presence of these amino acids had any effect on blastocyst cell number. D-Pro and the osmolytes Gly and Betaine did not improve embryo development in low-or high-density culture indicating the mechanism was stereospecific and not osmotic, respectively. L-Pro-and L-Glnmediated improvement in development is observed from the 5-cell stage and persists to the blastocyst stage. Molar excess of Gly, Betaine or L-Leu over L-Pro eliminated improvement in development and hatching consistent with them acting as competitive inhibitors of transporter-mediated uptake across the plasma membrane. The L-Pro effect is dependent on mTORC1 signaling (rapamycin sensitive) while that for L-Gln is not. The addition of L-Pro leads to significant nuclear translocation of p-Akt S473 at the 2-and 4-cell stages and of p-ERK1/2 T202/Y204 nuclear translocation at the 2-, 4-, and 8-cell stages. L-Pro improvement in embryo development involves mechanisms analogous to those seen with Pro-mediated differentiation of mouse ES cells, which is also stereoselective, dependent on transporter uptake, and activates Akt, ERK, and mTORC1 signaling pathways.

X‐linked retinitis pigmentosa (XLRP) accounts for a significant proportion of certifiable blindness in working‐age adults. The objectives of this study were to: (1) synthesize the best available evidence regarding the natural history of disease progression and (2) identify the best current clinical biomarkers for monitoring disease progression, which will be important in planned gene therapy trials for this condition. Patient population: XLRP affected males. Main outcomes: A systematic review of the literature was undertaken with data sought on overall annual progression for clinical biomarkers using optical coherence tomography (OCT), fundus autofluorescence (FAF), visual acuity, electroretinography and visual fields. To assess which outcome was best for monitoring progression, data on reliability, interocular correlation and structure‐function correlation were extracted. A total of 17 studies met the inclusion criteria. Studies estimated progression at between 4% to 19% per year with longitudinal data. Where an overall model was produced with cross‐sectional data, the trend was usually best fit by a logarithmic function with an annual exponential decline rate between 4.7% and 8.0%. The evidence suggested the ellipsoid zone (EZ) width on OCT and outer ring area (ORA) on FAF as the most useful biomarkers having excellent interocular symmetry, reproducibility and functional correlation. Using different clinical biomarkers, XLRP progresses at a rate of 4 to 19% per year. Ellipsoid zone (EZ) width and ORA are the most robust biomarkers with the potential to be used in trials where one eye serves as a control for the other.

No abstract