Plasma Steroid and Luteinizing Hormone Levels during Prostaglandin F2α Administration in Luteal Phase of Menstrual Cycle

An intravenous infusion of prostaglandin F₂α (12.5-250μg/min) was administered in four volunteers in the mid-late luteal phase and three in the early luteal phase of the menstrual cycle.Frequent measurement of plasma progesterone, oestrogens, and luteinizing hormone (LH) showed that administration of high doses depressed plasma progesterone levels in the late luteal phase and caused concomitant side effects. Levels of progesterone in the early luteal phase were unaffected. In both phases oestrogen and LH levels were little altered. In two subjects, hourly progesterone levels measured throughout the day at a similar time in a subsequent control menstrual cycle showed an appreciable variation in one but steady levels in the second. This variation may contribute to the magnitude of the fall in progesterone noted during the infusion of prostaglandins.     

Dynamics of the HD regulatory subdomain of PARP-1; substrate access and allostery in PARP activation and inhibition

PARP-1 is a key early responder to DNA damage in eukaryotic cells. An allosteric mechanism links initial sensing of DNA single-strand breaks by PARP-1’s F1 and F2 domains via a process of further domain assembly to activation of the catalytic domain (CAT); synthesis and attachment of poly(ADP-ribose) (PAR) chains to protein sidechains then signals for assembly of DNA repair components. A key component in transmission of the allosteric signal is the HD subdomain of CAT, which alone bridges between the assembled DNA-binding domains and the active site in the ART subdomain of CAT. Here we present a study of isolated CAT domain from human PARP-1, using NMR-based dynamics experiments to analyse WT apo-protein as well as a set of inhibitor complexes (with veliparib, olaparib, talazoparib and EB-47) and point mutants (L713F, L765A and L765F), together with new crystal structures of the free CAT domain and inhibitor complexes. Variations in both dynamics and structures amongst these species point to a model for full-length PARP-1 activation where first DNA binding and then substrate interaction successively destabilise the folded structure of the HD subdomain to the point where its steric blockade of the active site is released and PAR synthesis can proceed.     

Devitalization of Transgenic Seed That Preserves DNA and Protein Integrity

Agricultural biotechnology companies have been asked to provide intact transgenic seed to regulatory agencies as reference materials for evaluating transgene and protein detection methods (PCR and immunoassay). Due to intellectual-property and product-stewardship considerations, submission of devitalized seed prior to regulatory approval is preferable in any given country. Commonly used devitalization procedures, such as heating or autoclaving, degrade the protein and/or DNA rendering the seed unfit as a reference material for these tests. A novel method for devitalizing seed was developed that involves hydration, freezing in liquid nitrogen, and lyophilization. The devitalization method described here was found to preserve the transgenic DNA and protein in cotton (Gossypium hirsutum) and maize (Zea mays) seed allowing its use as a reference material for evaluating detection methods.     

Blood Coagulation Changes during Mid-trimester Abortion Induced by Prostaglandin F2α

Serial studies on the coagulation system were made during second-trimester abortion induced by extra-amniotic, intra-amniotic, vaginal, and intravenous prostaglandin F₂α. No significant changes were found in the prothrombin time, partial thromboplastin time, or levels of fibrin-fibrinogen degradation products. An increase in the activity of factor X occurred with all routes of administration; the activity of factor VIII increased during extra-amniotic, vaginal, and intravenous administration; factor V activity increased during extra-amniotic and vaginal administration; and the activity of factor VII-X complex increased slightly at the time of abortion with all methods.The findings suggest that though prostaglandin induction of second-trimester abortion produces changes in the coagulation system the effects are much less than those which accompany induction of abortion by hypertonic saline or abdominal delivery in late pregnancy.