Vasa previa in singleton pregnancies: diagnosis and clinical management based on an international expert consensus

Background: There are limited data to guide the diagnosis and management of vasa previa. Currently, what is known is largely based on case reports or series and cohort studies. Objective: This study aimed to systematically collect and classify expert opinions and achieve consensus on the diagnosis and clinical management of vasa previa using focus group discussions and a Delphi technique. Study design: A 4-round focus group discussion and a 3-round Delphi survey of an international panel of experts on vasa previa were conducted. Experts were selected on the basis of their publication record on vasa previa. First, we convened a focus group discussion panel of 20 experts and agreed on which issues were unresolved in the diagnosis and management of vasa previa. A 3-round anonymous electronic survey was then sent to the full expert panel. Survey questions were presented on the diagnosis and management of vasa previa, which the experts were asked to rate on a 5-point Likert scale (from "strongly disagree"=1 to "strongly agree"=5). Consensus was defined as a median score of 5. Following responses to each round, any statements that had median scores of ≤3 were deemed to have had no consensus and were excluded. Statements with a median score of 4 were revised and re-presented to the experts in the next round. Consensus and nonconsensus statements were then aggregated. Results: A total of 68 international experts were invited to participate in the study, of which 57 participated. Experts were from 13 countries on 5 continents and have contributed to >80% of published cohort studies on vasa previa, as well as national and international society guidelines. Completion rates were 84%, 93%, and 91% for the first, second, and third rounds, respectively, and 71% completed all 3 rounds. The panel reached a consensus on 26 statements regarding the diagnosis and key points of management of vasa previa, including the following: (1) although there is no agreement on the distance between the fetal vessels and the cervical internal os to define vasa previa, the definition should not be limited to a 2-cm distance; (2) all pregnancies should be screened for vasa previa with routine examination for placental cord insertion and a color Doppler sweep of the region over the cervix at the second-trimester anatomy scan; (3) when a low-lying placenta or placenta previa is found in the second trimester, a transvaginal ultrasound with Doppler should be performed at approximately 32 weeks to rule out vasa previa; (4) outpatient management of asymptomatic patients without risk factors for preterm birth is reasonable; (5) asymptomatic patients with vasa previa should be delivered by scheduled cesarean delivery between 35 and 37 weeks of gestation; and (6) there was no agreement on routine hospitalization, avoidance of intercourse, or use of 3-dimensional ultrasound for diagnosis of vasa previa. Conclusion: Through focus group discussion and a Delphi process, an international expert panel reached consensus on the definition, screening, clinical management, and timing of delivery in vasa previa, which could inform the development of new clinical guidelines

Metal-Substituted Microporous Aluminophosphates

This chapter aims to present the zeotypes aluminophosphates (AlPOs) as a complementary alternative to zeolites in the isomorphic incorporation of metal ions within all-inorganic microporous frameworks as well as to discuss didactically the catalytic consequences derived from the distinctive features of both frameworks. It does not intend to be a compilation of either all or the most significant publications involving metal-substituted microporous aluminophosphates. Families of AlPOs and zeolites, which include metal ion-substituted variants, are the dominant microporous materials. Both these systems are widely used as catalysts, in particular through aliovalent metal ions substitution. Here, some general description of the synthesis procedures and characterization techniques of the MeAPOs (metal-contained aluminophosphates) is given along with catalytic properties. Next, some illustrative examples of the catalytic possibilities of MeAPOs as catalysts in the transformation of the organic molecules are given. The oxidation of the hardly activated hydrocarbons has probably been the most successful use of AlPOs doped with the divalent transition metal ions Co2+, Mn2+, and Fe2+, whose incorporation in zeolites is disfavoured. The catalytic role of these MeAPOs is rationalized based on the knowledge acquired from a combination of the most advanced characterization techniques. Finally, the importance of the high specificity of the structure-directing agents employed in the preparation of MeAPOs is discussed taking N,N-methyldicyclohexylamine in the synthesis of AFI-structured materials as a driving force. It is shown how such a high specificity could be predicted and how it can open great possibilities in the control of parameters as critical in catalysis as crystal size, inter-and intracrystalline mesoporosity, acidity, redox properties, incorporation of a great variety of heteroatom ions or final environment of the metal site (surrounding it by either P or Al)

PP13, Maternal ABO Blood Groups and the Risk Assessment of Pregnancy Complications

Placental Protein 13 (PP13), an early biomarker of preeclampsia, is a placenta-specific galectin that binds beta-galactosides, building-blocks of ABO blood-group antigens, possibly affecting its bioavailability in blood.We studied PP13-binding to erythrocytes, maternal blood-group effect on serum PP13 and its performance as a predictor of preeclampsia and intrauterine growth restriction (IUGR). Datasets of maternal serum PP13 in Caucasian (n = 1078) and Hispanic (n = 242) women were analyzed according to blood groups. In vivo, in vitro and in silico PP13-binding to ABO blood-group antigens and erythrocytes were studied by PP13-immunostainings of placental tissue-microarrays, flow-cytometry of erythrocyte-bound PP13, and model-building of PP13--blood-group H antigen complex, respectively. Women with blood group AB had the lowest serum PP13 in the first trimester, while those with blood group B had the highest PP13 throughout pregnancy. In accordance, PP13-binding was the strongest to blood-group AB erythrocytes and weakest to blood-group B erythrocytes. PP13-staining of maternal and fetal erythrocytes was revealed, and a plausible molecular model of PP13 complexed with blood-group H antigen was built. Adjustment of PP13 MoMs to maternal ABO blood group improved the prediction accuracy of first trimester maternal serum PP13 MoMs for preeclampsia and IUGR.ABO blood group can alter PP13-bioavailability in blood, and it may also be a key determinant for other lectins' bioavailability in the circulation. The adjustment of PP13 MoMs to ABO blood group improves the predictive accuracy of this test

Evaluation of sorbate/reactant shape-selectivity of zeolites by GC pulse techniques

Rapid evaluation of sorbate/reactant shape-selectivity of medium-pore zeolites at operating conditions using isothermal and non-isothermal techniques (i.e., temperature-programmed desorption under Chromatographie conditions) has been described. The shape-selectivity of silicalite in sorption of sorbates having different critical sizes and configurations has been investigated at temperatures at which catalytic processes occur. The configuration and compressibility of bulkier sorbate molecules are much more important than critical molecular size in determining the shape-selective sorption/diffusion in medium-pore zeolites. GC pulse methods provide very simple and rapid means for studying molecular sieving and/or relative sorbate/reactant selectivity for bulkier sorbates undergoing configurational diffusion in the zeolites

Influence of coke deposition on acidity, intercrystalline mass transfer and catalytic properties of Pt-H-ZSM-5.Al<SUB>2</SUB>O<SUB>3</SUB> catalyst

Influence of coke deposition on Pt . H-ZSM-5 Al<SUB>2</SUB>O<SUB>3</SUB> catalyst on its acidity distribution, intercrystalline mass transfer, and catalytic activity/selectivity (in iso-octane cracking, o-xylene isomerization and methanol-to-aromatics conversion) has been investigated by carrying out measurements on the catalyst with different extents of coke deposition. The effective intercrystalline diffusivity of iso-octane (which does not penetrate the zeolite channels) in the catalyst at 473 K was measured by the GC pulse technique. The coke deposition has resulted in an increase in the adsorption. apparent heat of adsorption of iso-octane, and xylene isomerization activity, but a decrease in the intercrystalline diffusivity of iso-octane and para selectivity in the o-xylene isomerization and methanol conversion reactions. The influence of coke deposition (to different extents) on the catalyst on its surface, intercrystalline mass transfer, and catalytic activity/selectivity in the above reactions has been discussed

Sorption properties of crystalline molecular sieve AlPO<SUB>4</SUB>-5

The sorption capacity of a number of sorbates, viz. alcohols and hydrocarbons, and the isotherms of sorption of methanol, n-hexane, and benzene in AlPO4-5 at 313 K were measured by gravimetric technique. The isotherms of sorption of n-hexane, cyclohexane, benzene, and pyridine in the AlPO4-5, at higher temperatures (523-673 K) were determined by the GC peak maxima method. The isosteric heats of sorption of these sorbates at different sorbate loadings were obtained from the isotherm data. The heat of sorption near zero sorbate loading was determined separately by the GC pulse technique in the temperature range 523-673 K. The sorption capacities of AlPO4-5 for the sorbates, differing widely in their dipole moments and critical molecular sizes, have been found to be nearly the same (about 0.14 cm3 . g-1). The sorption of methanol, n-hexane, and benzene at 313 K occurs by the volume filling mechanism and the total volume of the sorption space in AlPO4-5 has been found to be about 0.14 cm3 . g-1. The sorption of n-hexane, cyclohexane, benzene, and pyridine at the higher temperatures follows the Freundlich isotherm. The influence of sorbate loading on the isosteric heat of sorption of benzene is very weak but the influence in the case of the other sorbates is very strong, particularly at the higher sorbate loadings. With the increase in the sorbate loading, the heat of sorption of n-hexane and pyridine increases and that of cyclohexane decreases. The heat of sorption of pyridine is much higher than that of the other sorbates. The values of the heat of sorption of n-hexane, cyclohexane, and benzene at near zero sorbate loading, obtained by the two methods, are very close to each other, and there is very good agreement between the heats of sorption obtained by the two methods. Analysis of the entropy change data for the high-temperature sorption reveals that the sorption of all the sorbates is mobile; the sorption of n-hexane at lower sorbate loading, in particular, and that of cyclohexane and benzene are "supermobile". However, in the case of sorption of n-hexane at higher sorbate loadings and pyridine, the sorbed molecules lose some of their rotational degrees of freedom