Protein S levels are lower in women receiving desogestrel-containing combined oral contraceptives (COCs) than in women receiving levonorgestrel-containing COCs at steady state and on cross-over Summary. This study aimed to identify specific haemostatic changes that might account for previous observations of higher venous thromboembolic risk among users of combined oral contraceptives (COCs) containing desogestrel (DSG) than levonorgestrel (LNG). Sixty-three current users of monophasic 30 mg oestrogen COCs containing either LNG or DSG omitted one pill-free interval (PFI), switching immediately either to the opposite formulation for one cycle or continuing with the same pill. Venesection followed the initial PFI after one cycle (21 tablets) and two cycles (42 tablets) of continuous pill taking, and after the following PFI. Protein S was lower in users of DSG than LNG formulations after the first PFI (mean^SD, 0´67^0´09 vs 0´76^0´10, P , 0´001) and after one cycle (0´61^0´09 vs 0´76^0´09, P , 0´0001). Protein S decreased when switching from LNG to DSG pills (0´77^0´07±0´65^0´06, P , 0´0001), mirrored by an increase at switching from DSG to LNG formulations (0´61^0´08±0´73^0´10, P , 0´005). Mean protein S levels remained within the normal range. Three different markers of thrombin generation remained unaltered. Potential explanations for COC-related thrombotic events are`acquired resistance to activated protein C' or inhibition of fibrinolysis. A potential role has been described for protein S deficiency in both. A further triggering factor is a probable prerequisite for actual thrombosis, but pill-takers whose levels of protein S were in the lowest percentiles may be at greatest risk.
In an attempt to clarify whether or not glutaraldehyde molecules contribute to the effective osmotic pressure of the fixative solution the ultrastructure of noncultured and in vitro-cultured day 1 3 and 4 rabbit embryos was evaluated. Total osmolarity of the fixative solution (200–800 mosm) was only varied by changing the aldehyde concentration, whereas the vehicle osmolarity (145 mosm) remained unchanged. Optimum preservation in all embryonic stages was obtained when total osmolarity of the fixative solution was 285–340 mosm. Higher (480–800 mosm) or lower (250 mosm) osmolarities of the fixative solution led to alterations mainly in mitochondria and smooth-surfaced endoplasmic reticulum. Shrinkage of cells and condensation of the cytoplasm occurred only occasionally. Compared with early cleavage stage embryos blastocysts were generally more susceptible to hyperton and hypoton fixative solutions. In vitro culture for 24 h per se did not have any influence on the fixation.
Parity is a major determinant of success rate in medical abortion: a retrospective analysis of 3161 consecutive cases of early medical abortion treated with reduced doses of mifepristone and vaginal gemeprost.
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