Update on preimplantation genetic diagnosis and screening

Recent advancement in both human embryology and genomics has created a completely new situation for practical and widespread application of preimplantation genetic diagnosis and screening with a dramatic effect on assisted reproduction. The mapping of the first human genome and the advancement in sequencing technology and bioinformatics has led to the discovery of the exact genetic background of exponentially increasing number of diseases. In parallel, methods for culturing human embryos have also radically improved, enabling the late transfer, and the procedure of vitrification the safe cryopreservation. In consequence, refined genetic analyses have become available from blastocyst biopsy followed by the application of novel genomic methods. Furthermore, some studies suggest that by the selection of aneuploid embryos the pregnancy- and birth-rates can be increased. The amount and the depth of information obtainable from the embryos raise several technical and ethical questions that can be answered by further prospective randomized trials. Orv. Hetil., 2014, 155(35), 1375–1382.

The development of chinook (Oncorhynchus tshawytscha) and chum salmon (Onchorhynchus keta) embryos and alevins under varying temperature regimes

Chinook (Oncorhynchus tshawytscha) and chum salmon (O. keta) embryos were initially incubated at 4, 8, or 12 °C and then maintained at the same temperature or systematically transferred at completion of epiboly (early transfer) or complete eye pigmentation (late transfer) to each of the other incubation temperatures. For both species initial incubation at 8 or 12 °C resulted in higher embryo and alevin survival rates than initial incubation at 4 °C. Increasing or decreasing temperature regimes had little effect on embryo and alevin survival rates. Transfers after epiboly or completion of eye pigmentation had little influence on subsequent survival rates, except the early and late transfers of chinook salmon embryos from 4 to 12 °C, which resulted in an increase in alevin mortality. Hatching and emergence times varied inversely with temperature, and chum salmon generally hatched and emerged sooner than chinook salmon. Decreasing temperature regimes produced longer and heavier chinook salmon alevins and fry, but constant incubation at 8 °C or early or later transfers to 8 °C resulted in longer and heavier chum salmon alevins and fry. Temperature regimes that simulate those experienced by a species during natural incubation tend to enhance survival and alevin and fry size. Different trends in embryo and alevin developmental characters between species and among families within a species were assumed to reflect adaptations to variable natural incubation conditions.

Biokinetics of Bone Tracers by Means of Deconvolution Analysis - Comparison of 99mTc MDP, 99mTc DPD and 99mTc EHDP

Transfer functions of 99mTc methylene diphosphonate (MDP), 99mTc 2,3-dicarboxypropane-l,l-diphosphonate (DPD) and 99mTc ethane-l-hydroxy-l,l-diphosphonate (EHDP) into bone and extravascular fluid of soft tissues were determined in 5 dogs by deconvolution analysis of the time-course of plasma, soft tissue and bone radioactivity. The transfer rates 5 min after injection - indicating the rapid exchange of the tracer between plasma and the extravascular fluid -decrease in the order MDP > EHDP > DPD (P < 0.05). The transfer rates into bone - determined from transfer rates between 30 and 60 min - decreased in a different order, i.e. MDP > DPD > EHDP (P<0.05). The fractional bone uptake of diphosphonates estimated from the ratio of early to late transfer rates was slightly greater for DPD than for MDP and EHDP respectively. The difference between DPD and MDP was not significant (P > 0.05). The average bone and soft tissue concentrations of DPD 60 min after injection were greater than that of MDP and EHDP due to different plasma concentrations (DPD > EHDP > MDP), whereas the bone-to-soft tissue ratios decreased in the sequence MDP > DPD > EHDP (P < 0.05). - Our results reveal different biokinetics of MDP, DPD and EHDP explaining variations in osseous and soft tissue uptake suggesting that deconvolution analysis could play an important role in bone scan interpretation.