Prospective randomized study of an ultrashort gonadotrophin-releasing hormone agonist versus a modified suppression protocol for ovarian stimulation in intracytoplasmic sperm injection cycles.

To compare oocyte quality and clinical outcome after an ultrashort or a modified suppression gonadotrophin-releasing hormone agonist (GnRHa) protocol for ovarian stimulation in intracytoplasmic sperm injection (ICSI) cycles, we conducted a prospective randomized study of 60 consecutive couples with severe male infertility admitted for their first in-vitro fertilization (IVF) and ICSI attempt. More cycles were cancelled after the ultrashort protocol (8/30) than after the modified suppression protocol (3/30), although the difference was not significant. There were no cases of severe ovarian hyperstimulation syndrome (OHSS) in the ultrashort group compared to three cases in the suppression group. The percentage of mature metaphase II oocytes recovered in both groups was similar (88 versus 86%), as were the fertilization or cleavage rates after ICSI. In the ultrashort group, a total of 64 embryos was replaced in 22 transfers (mean 2.9 embryos per transfer), resulting in three first trimester abortions and seven deliveries. In the suppression group, 11 deliveries were achieved after transfer of a total of 75 embryos in 27 patients (mean 2.8 embryos per transfer). In conclusion, there was no apparent difference between the two GnRHa protocols in terms of oocyte quality and clinical outcome. However, because of the lower rate of severe OHSS, in our study the ultrashort protocol was more appropriate for ovarian stimulation in ICSI cycles than the modified suppression protocol.

Uptake and endocytic pathway of transferrin and iron in perfused rat liver.

Uptake and distribution of transferrin and iron in perfused rat liver are dependent on perfusion temperature, time and uptake affinity. Transferrin passes at least two different compartments on its receptor-mediated recycling pathway, which are separable by centrifugation in a shallow Nycodenz gradient. Perfusion at lowered temperature (16 degrees C) is sufficient for internalization of transferrin and iron. Passage of radiolabelled iron to other than endosomal compartments as well as recycling of labelled transferrin are largely suppressed at this perfusion temperature, as much less is released by further perfusion with unlabelled transferrin than at 4 degrees C where the ligand is largely washed off the surface, or 37 degrees C, where the recycling pathway is operating. But also at lowered temperature only a part of the iron in endosomal fractions can be assigned to transferrin. A considerable part of the total uptake of transferrin and iron can be attributed to low-affinity mechanisms even at very low transferrin concentrations. Transferrin receptors are concentrated in endosomal fractions in comparison to fractions representing different plasma membrane domains of the liver. Endosomal fractions specifically display detergent-activated NADH-acceptor oxidoreductase which may be part of the iron uptake system.