Management of lithium dosing around delivery: An observational study

Objectives: Recommendations on lithium dosing around delivery vary, with several guidelines suggesting that lithium should be discontinued prior to delivery. We aimed to evaluate the validity of these recommendations by investigating 1) maternal lithium blood level changes following delivery, and 2) the association between neonatal lithium blood levels at delivery and neonatal outcomes. Methods: In this retrospective observational cohort study, we included women with at least one lithium blood level measurement during the final week of pregnancy and the first postpartum week. For aim 2, we included a subcohort of women with neonates for whom neonatal lithium blood levels (obtained from the umbilical cord or a neonatal vein puncture within 24 hours of delivery) were available. Results: There were a total of 233 maternal lithium blood level measurements; 55 (23.6%) in the week before delivery and 178 (76.4%) in the week after. There was no association between time and lithium blood level/dose ratio (Pearson correlation coefficient −0.03, P =.63). Additionally, we included a total of 29 neonates for whom a lithium measurement was performed within 24 hours postpartum. Maternal and neonatal lithium blood levels were strongly correlated. We observed no associations between neonatal lithium blood levels at delivery and neonatal outcomes. Conclusion: Based on our findings, we do not recommend lowering the dosage or discontinuation of lithium prior to delivery. Stable dosing can prevent subtherapeutic lithium serum levels, which is especially important in the postpartum period when relapse risks are highest

Release of nontransmembrane full-length Alzheimer's amyloid precursor protein from the lumenar surface of chromaffin granule membranes

We previously demonstrated the presence of a soluble form of full- length Alzheimer's amyloid precursor protein (APP) in the lumen of adrenal medullary chromaffin granules (CG). Furthermore, full-length APP is released from CG membranes in vitro at pH 9.0 by an enzymatic mechanism, sensitive to protease inhibitors [Vassilacopoulou et al. (1995) J. Neurochem. 64, 2140- 2146]. In this study, we found that when intact CG were subjected to exogenous trypsin, a fraction of APP was not digested, consistent with an intragranular population of APP. To examine the substrate-product relationship between membrane and soluble full-length APP, we labeled CG transmembrane APP with 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine ([125I]TID), a lipophilic probe, specific for membrane-spanning domains of proteins. APP released from the membranes at pH 9.0 was not labeled with [125I]TID. In addition, this APP was not biotinylated in intact CG. Combined, the results indicate that APP released from CG membranes derives from a unique nontransmembrane population of membrane-associated APP, located in the lumenal side of CG membranes. Dithiobis(succinimidylpropionate) (DSP) cross-linking indicated that APP in CG is situated in close proximity with other proteins, possibly with APP itself. APP complexes were also detected under nonreducing conditions, without DSP cross-linking. These results, combined with our previous studies, indicate that full-length APP within CG exists as three different populations: (I) transmembrane, (II) membrane- associated/nontransmembrane, and (III) soluble. The existence of nontransmembrane populations suggests that putative γ-secretase cleavage sites of APP, assumed to be buried within the lipid bilayer, could be accessible to proteolysis in a soluble intravesicular environment