RESUMO
OBJECTIVE: To determine the performance of a multiparametric test comprising maternal risk factors, uterine artery Doppler and ophthalmic artery Doppler in the first trimester of pregnancy for the prediction of pre-eclampsia (PE). METHODS: This prospective observational cohort study recruited patients in the first trimester of pregnancy. Maternal uterine artery and ophthalmic artery Doppler assessments were performed in 440 singleton pregnancies at 11-14 weeks of gestation. Additional history was obtained through participant questionnaires, and follow-up occurred to discharge postdelivery. The normotensive and pre-eclamptic groups were compared using parametric (Student's t-test) and non-parametric (Mann-Whitney U-test) tests. Univariable and multivariable logistic regression analyses were performed to determine which biophysical factors, and which of the factors among the maternal characteristics and medical and obstetric history, had a significant contribution to the prediction of PE in a multiparametric model. RESULTS: Thirty-one (7%) patients developed PE, including nine (2%) who required delivery before 34 weeks (early PE) and 22 (5%) with late PE. There were statistically significant differences in uterine artery pulsatility index (UtA-PI) and ophthalmic artery first diastolic peak (PD1) mean values between the PE and control groups. In a multiparametric model, both UtA-PI and PD1 achieved a 67% detection rate for early PE, although when combined, the detection rate only increased to 68%. CONCLUSIONS: The efficiency of ophthalmic artery PD1 in the first trimester as a predictive marker for the later development of PE was approximately equal to that described for uterine artery Doppler. Although these findings do not support the replacement of uterine artery Doppler analysis in multiparametric predictive models for PE, they do provide novel insights into first-trimester maternal systemic vascular changes that precede the clinical development of this condition.
Assuntos
Artéria Oftálmica/diagnóstico por imagem , Pré-Eclâmpsia/diagnóstico por imagem , Ultrassonografia Doppler de Pulso/métodos , Adulto , Índice de Massa Corporal , Estudos de Coortes , Feminino , Humanos , Valor Preditivo dos Testes , Gravidez , Primeiro Trimestre da Gravidez , Estudos Prospectivos , Sensibilidade e Especificidade , Inquéritos e Questionários , Artéria Uterina/diagnóstico por imagemRESUMO
Misfolding and misassembly of proteins are major problems in the biotechnology industry, in biochemical research, and in human disease. Here we describe a novel approach for reversing aggregation and increasing refolding by application of hydrostatic pressure. Using P22 tailspike protein as a model system, intermediates along the aggregation pathway were identified and quantitated by size-exclusion high-performance liquid chromatography (HPLC). Tailspike aggregates were subjected to hydrostatic pressures of 2.4 kbar (35,000 psi). This treatment dissociated the tailspike aggregates and resulted in increased formation of native trimers once pressure was released. Tailspike trimers refolded at these pressures were fully active for formation of infectious viral particles. This technique can facilitate conversion of aggregates to native proteins without addition of chaotropic agents, changes in buffer, or large-scale dilution of reagents required for traditional refolding methods. Our results also indicate that one or more intermediates at the junction between the folding and aggregation pathways is pressure sensitive. This finding supports the hypothesis that specific determinants of recognition exist for protein aggregation, and that these determinants are similar to those involved in folding to the native state. An increased understanding of this specificity should lead to improved refolding methods.
Assuntos
Glicosídeo Hidrolases/química , Proteínas da Cauda Viral/química , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão , Eletroforese em Gel de Poliacrilamida , Pressão Hidrostática , Conformação Proteica , Dobramento de Proteína , Espectrometria de FluorescênciaRESUMO
Bacteriophage P22 belongs to a family of double-stranded DNA viruses that share common morphogenetic features like DNA packaging into a procapsid precursor and maturation. Maturation involves cooperative expansion of the procapsid shell with concomitant lattice stabilization. The expansion is thought to be mediated by movement of two coat protein domains around a hinge. The metastable conformation of subunit within the procapsid lattice is considered to constitute a late folding intermediate. In order to understand the mechanism of expansion it is necessary to characterize the interactions stabilizing procapsid and mature capsid lattices, respectively. We employ pressure dissociation to compare subunit packing within the procapsid and expanded lattice. Procapsid shells contain larger cavities than the expanded shells, presumably due to polypeptide packing defects. These defects contribute to the metastable nature of the procapsid lattice and are cured during expansion. Improved packing contributes to the increased stability of the expanded shell. Comparison of two temperature-sensitive folding (tsf) mutants of coat protein (T294I and W48Q) with wild-type coat revealed that both mutations markedly destabilized the procapsid shell and yet had little effect on relative stability of the monomeric subunit. Thus, the regions affected by these packing defects constitute subunit interfaces of the procapsid shell. The larger activation volume of pressure dissociation observed for both T294I and W48Q indicates that the decreased stability of these particles is due to increase of cavity defects. These defects in the procapsid lattice are cured upon expansion suggesting that the intersubunit contacts affected by tsf mutations are absent or rearranged in the mature shell. The energetics of the in vitro expansion reaction also suggests that entropic stabilization contributes to the large free energy barrier for expansion.