Accuracy of mean arterial pressure and blood pressure measurements in predicting pre-eclampsia: systematic review and meta-analysis

Objective To determine the accuracy of using systolic and diastolic blood pressure, mean arterial pressure, and increase of blood pressure to predict pre-eclampsia.Design Systematic review with meta-analysis of data on test accuracy.Data sources Medline, Embase, Cochrane Library, Medion, checking reference lists of included articles and reviews, contact with authors.Review methods Without language restrictions, two reviewers independently selected the articles in which the accuracy of blood pressure measurement during pregnancy was evaluated to predict pre-eclampsia. Data were extracted on study characteristics, quality, and results to construct 2×2 tables. Summary receiver operating characteristic curves and likelihood ratios were generated for the various levels and their thresholds.Results 34 studies, testing 60 599 women (3341 cases of pre-eclampsia), were included. In women at low risk for pre-eclampsia, the areas under the summary receiver operating characteristic curves for blood pressure measurement in the second trimester were 0.68 (95% confidence interval 0.64 to 0.72) for systolic blood pressure, 0.66 (0.59 to 0.72) for diastolic blood pressure, and 0.76 (0.70 to 0.82) for mean arterial pressure. Findings for the first trimester showed a similar pattern. Second trimester mean arterial pressure of 90 mm Hg or more showed a positive likelihood ratio of 3.5 (95% confidence interval 2.0 to 5.0) and a negative likelihood ratio of 0.46 (0.16 to 0.75). In women deemed to be at high risk, a diastolic blood pressure of 75 mm Hg or more at 13 to 20 weeks’ gestation best predicted pre-eclampsia: positive likelihood ratio 2.8 (1.8 to 3.6), negative likelihood ratio 0.39 (0.18 to 0.71). Additional subgroup analyses did not show improved predictive accuracy.Conclusion When blood pressure is measured in the first or second trimester of pregnancy, the mean arterial pressure is a better predictor for pre-eclampsia than systolic blood pressure, diastolic blood pressure, or an increase of blood pressure.     

Lipase-mediated Resolution of Branched Chain Fatty Acids

Branched chain fatty acids (BCFAs) are fatty acids substituted with alkyl groups. Many of them are chiral and therefore occur in two enantiomeric forms. This review describes their occurrence in Nature, their biosynthesis, their properties as flavours, and their enzymatic kinetic resolution. Many lipases are able to separate the enantiomers of BCFAs, in hydrolysis, esterification or transesterification reactions. Very often, the stereoselectivity of these reactions is remarkably high, even when the chiral carbon atom is remote from the carboxylic acid group.     

Reactor Design for the Novozym 435 ® -catalysed Enantioselective Esterification of 4-methyloctanoic Acid

The bench scale Novozym 435 ® catalysed esterification of 4-methyloctanoic acid with ethanol was studied at 35°C. Esterification in a batch reactor (molar ratio of 1:8 (acid:EtOH)) resulted in the isolation of the enantiomerically enriched product (ee p =81%) and substrate (ee s =93%). In order to integrate reaction and separation, liquid-vapour equilibria calculations were performed showing that an excess of ethanol results in a very low ester fraction in the vapour phase. Since this is undesirable for an integrated process of reaction and product removal, a repeated batch reaction was performed using a molar ratio of 10:1 (acid:EtOH). After six cycles (45% conversion) the ee of 4-methyloctanoic acid ethyl ester turned out to be 80%. For different E values the ee p was calculated for batch and repeated batch reactions. It was shown that in all cases the ee p was higher for the repeated batch reaction. However, the product is not enantiopure since the E value of the reaction is rather low at the low ethanol concentration used. An alternative approach would be the continuous separation of the product during the reaction. A mathematical model was developed to describe esterification in a packed bed reactor integrated with product separation. This model shows that integration of reaction and product removal in advance is not suitable either to obtain an enantiomerically pure product. Since the optimal reaction conditions (high ethanol concentration) and the optimal separation system (low ethanol concentration) do not match in this reaction, the preference is given to the batch reaction at high ethanol concentrations because in that case the highest enantioselectivity of the enzyme is obtained.     

Identification of cis-acting elements involved in 3'-end formation of Saccharomyces cerevisiae 18S rRNA.

In yeast, the 3' end of mature 18S rRNA is generated by endonucleolytic cleavage of the 20S precursor at site D. Available data indicate that the major cis-acting elements required for this processing step are located in relatively close proximity to the cleavage site. To identify these elements, we have studied the effect of mutations in the mature 18S and ITS1 sequences neighboring site D on pre-rRNA processing in vivo. Using clustered point mutations, we found that alterations in the sequence spanning site D from position -5 in 18S rRNA to +6 in ITS1 reduced the efficiency of processing at this site to different extents as demonstrated by the lower level of the mature 18S rRNA and the increase in 20S pre-rRNA in cells expressing only mutant rDNA units. More detailed analysis revealed an important role for the residue located 2 nt upstream from site D (position -2), whereas sequence changes at position -1, +1, and +2 relative to site D had no effect. The data further demonstrate that the proposed base pairing between the 3' end of 18S rRNA and the 5' end of ITS1 is not important for efficient and accurate processing at site D, nor for the formation of functional 40S ribosomal subunits. These results were confirmed by analyzing the accumulation of the D-A2 fragment derived from the mutant 20S pre-rRNA in cells that lack the Xrn1p exonuclease responsible for its degradation. The latter results also showed that the accuracy of cleavage was affected by altering the spacer sequence directly downstream of site D but not by mutations in the 18S rRNA sequence preceding this site.     

Effect of growth parameters on the residual activity of Lactobacillus plantarum after drying

In order to select optimal conditions for the production of dry and active starter cultures it is important to determine the influence of growth conditions on the residual activity of dried bacteria. The influence of medium composition, pH during growth, continuous vs batch reactor and growth phase was studied on the residual activity of Lactobacillus plantarum after drying. The effect of high sodium chloride concentrations during growth on the residual activity of Lact. plantarum after drying was measured. The samples were dried by convection and in a fluidized bed. Bacteria with the highest residual activity after drying were produced in batch or chemostat with pH-controlled growth using enriched or diluted MRS medium. The presence of 1 or 1·25 mol l⁻¹ NaCl during growth resulted in a decreased residual activity after drying. Variations in growth conditions (application of stress) generally did not result in higher residual activities after drying.     

Modeling the Interactions of Lactobacillus curvatus Colonies in Solid Medium: Consequences for Food Quality and Safety

The growth process of Lactobacillus curvatus colonies was quantified by a coupled growth and diffusion equation incorporating a volumetric rate of lactic acid production. Analytical solutions were compared to numerical ones, and both were able to predict the onset of interaction well. The derived analytical solution modeled the lactic acid concentration profile as a function of the diffusion coefficient, colony radius, and volumetric production rate. Interaction was assumed to occur when the volume-averaged specific growth rate of the cells in a colony was 90% of the initial maximum rate. Growth of L. curvatus in solid medium is dependent on the number of cells in a colony. In colonies with populations of fewer than 10⁵ cells, mass transfer limitation is not significant for the growth process. When the initial inoculation density is relatively high, colonies are not able to grow to these sizes and growth approaches that of broth cultures (negligible mass transfer limitation). In foods, which resemble the model solid system and in which the initial inoculation density is high, it will be appropriate to use predictive models of broth cultures to estimate growth. For a very low initial inoculation density, large colonies can develop that will start to deviate from growth in broth cultures, but only after large outgrowth.     

Different effects of 2-n-heptyl-4-hydroxyquinoline-N-oxide on oxygen and nitrate respiration in Klebsiella aerogenes

The inhibition of the oxidase and respiratory nitrate reductase activity in membrane preparations from Klebsiella aerogenes by 2-n-heptyl-4-hydroxyquinoline-N-oxide (HQNO) has been investigated. Addition of HQNO only slightly affected the aerobic steady-state reduction of cytochrome b₅₅₉ with NADH, but caused a significantly lower nitrate reducing steady-state of this cytochrome. The changes in the redox states of the cytochromes during a slow transition from anaerobic to aerobic conditions in the presence and absence of HQNO showed that the inhibition site of HQNO is located before cytochrome d. Inhibition patterns obtained upon titration of the NADH oxidase and NADH nitrate reductase activity with HQNO indicated one site of inhibitor interaction in the NADH nitrate reductase pathway and suggested a multilocated inhibition of the NADH oxidase pathway. Difference spectra with ascorbate-dichlorophenolindophenol as electron donor indicated the presence of a cytochrome b₅₆₃ component which was not oxidized by nitrate, but was rapidly oxidized by oxygen. The latter oxidation was prevented by HQNO. A scheme for the electron transport to oxygen and nitrate is presented. In the pathway to oxygen, HQNO inhibits both at the electron-accepting side of cytochrome b₅₅₉ and at the electron-donating side of cytochrome b₅₆₃, whereas in the pathway to nitrate, inhibition occurs only at the electron-accepting side of cytochrome b₅₅₉.     

Aspiration and cytological evaluation of idiopathic bone cavities of the jaw

The idiopathic bone cavity (IBC) is an intraosseous pseudocyst devoid of epithelial lining. Clinically, IBCs of the jaw are asymptomatic and normally found in routine radiographic exams. Although the literature regarding the content of IBCs is controversial, the final diagnosis is usually aided by the discovery of an empty cavity upon surgical exploration. The aim of this study was to perform cytological and histological analysis of IBC contents. Cytological analysis of nine cases of IBC was performed after puncture and processed by the cell block technique. Histological analysis was performed in six cases in which it was possible to collect enough material by curettage of bone walls. Remarkably, cell block analysis revealed the presence of fibrin, often arranged as a net; erythrocytes; and inflammatory cells, with a predominance of lymphocytes as well as some macrophages and neutrophils. Histological analysis showed the presence of scant connective tissue, bone trabeculae, hemorrhagic foci, and hemosiderin. Only two cases presented scattered multinucleated giant cells. Cytological evaluation of IBC content by the cell block technique might represent a useful diagnostic tool, especially in cases in which there is no available material for curettage in the cavity.