Adenine nucleotide translocation in liver mitochondria of hypothyroid rats

In measurements using a disc filtration method, liver mitochondria obtained from hypothyroid rats translocate external ADP at 0 [deg]C via the atractyloside-sensitive carrier much more slowly than do mitochondria from normal rats, confirming the findings of Portnay et al. (Biochem. Biophys. Res. Commun. 55, 17, 1973). The hypothyroid mitochondria contain 60% more ATP + ADP than do mitochondria from normals, but the excess nucleotides are not exchangeable and so do not contribute to translocation. A decrease in the first-order rate constant accounts for the decreased velocity. Neither a decrease in the number of translocator sites nor changes in ADP phosphorylation or ATPase activity seem to account for the abnormal kinetics of translocation. Although the filtration method limits the maximal translocation rate observed in normal mitochondria at temperatures above 17 [deg]C that induce a fluid membrane state, no such transition is seen in mitochondria from hypothyroid rats up to 35 [deg]C, indicating that the translocator is in an altered environment in hypothyroidism. Injecting a hypothyroid rat once with -thyroxine corrects the abnormal compartmentation and produces a temperature-rate relationship like that in normal mitochondria in 3 days, a period which would accommodate the hormone actions reported on translation, membrane phospholipid synthesis, or fatty acid desaturation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22994/1/0000562.pd

Thyroid hormone action on mitochondria

Measurements of fluorescence at >420 nm and extracted NADPH in mitochondria obtained from the livers of hypothyroid rats show that the addition of Pi, ADP and glutamate rapidly reduces over 90% of the total reducible intrinsic pyridine nucleotides in State 3, compared with 20% in normals. The total fluorescence intensity change and reducible NADP + is about twice normal in hypothyroid mitochondria. Adding 6–30 µM l -thyroxine to hypothyroid mitochondria in vitro decreases and delays the substrate-induced reduction of pyridine nucleotides, and excludes both NADP + from such reduction and NADPH from oxidation by added ADP + Pi, without changing the high NADP(H) content. The correcting actions of the hormone are rapidly reversed by albumin, probably by binding free hormone. Changes in respiration do not appear to account for these observations. There is indirect evidence for decreased phosphorylation of added ADP in hypothyroid mitochondria, and a correction by added hormone. The hormonal actions on NADP(H) redox reactions are not reproduced by 1 to 6 µM dinitrophenol in vitro . l -Thyroxine appears to specifically block the participation of NADP (H) in redox reactions in mitochondria from hypothyroid rats, perhaps by effecting a sequestration of the nucleotide, by inhibiting the pyridine nucleotide transhydrogenase, or by activating an energy-linked process that competes with transhydrogenation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44803/1/10863_2004_Article_BF00761448.pd

Planned early delivery or expectant management for late preterm pre-eclampsia (PHOENIX): a randomised controlled trial

© 2019 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license Background: In women with late preterm pre-eclampsia, the optimal time to initiate delivery is unclear because limitation of maternal disease progression needs to be balanced against infant complications. The aim of this trial was to determine whether planned earlier initiation of delivery reduces maternal adverse outcomes without substantial worsening of neonatal or infant outcomes, compared with expectant management (usual care) in women with late preterm pre-eclampsia. Methods: In this parallel-group, non-masked, multicentre, randomised controlled trial done in 46 maternity units across England and Wales, we compared planned delivery versus expectant management (usual care) with individual randomisation in women with late preterm pre-eclampsia from 34 to less than 37 weeks' gestation and a singleton or dichorionic diamniotic twin pregnancy. The co-primary maternal outcome was a composite of maternal morbidity or recorded systolic blood pressure of at least 160 mm Hg with a superiority hypothesis. The co-primary perinatal outcome was a composite of perinatal deaths or neonatal unit admission up to infant hospital discharge with a non-inferiority hypothesis (non-inferiority margin of 10% difference in incidence). Analyses were by intention to treat, together with a per-protocol analysis for the perinatal outcome. The trial was prospectively registered with the ISRCTN registry, ISRCTN01879376. The trial is closed to recruitment but follow-up is ongoing. Findings: Between Sept 29, 2014, and Dec 10, 2018, 901 women were recruited. 450 women (448 women and 471 infants analysed) were allocated to planned delivery and 451 women (451 women and 475 infants analysed) to expectant management. The incidence of the co-primary maternal outcome was significantly lower in the planned delivery group (289 [65%] women) compared with the expectant management group (338 [75%] women; adjusted relative risk 0·86, 95% CI 0·79–0·94; p=0·0005). The incidence of the co-primary perinatal outcome by intention to treat was significantly higher in the planned delivery group (196 [42%] infants) compared with the expectant management group (159 [34%] infants; 1·26, 1·08–1·47; p=0·0034). The results from the per-protocol analysis were similar. There were nine serious adverse events in the planned delivery group and 12 in the expectant management group. Interpretation: There is strong evidence to suggest that planned delivery reduces maternal morbidity and severe hypertension compared with expectant management, with more neonatal unit admissions related to prematurity but no indicators of greater neonatal morbidity. This trade-off should be discussed with women with late preterm pre-eclampsia to allow shared decision making on timing of delivery. Funding: National Institute for Health Research Health Technology Assessment Programme