Substantial discrepancies in 17β‐oestradiol concentrations obtained with three different commercial direct radioimmunoassay kits in rat sera

The extensive use of oestrogen for contraception and amelioration of post‐menopausal symptoms has made it the subject of substantial recent research efforts, and ovariectomized (ovx) rats treated with exogenous ovarial hormones are important when investigating the effects and mechanisms of oestrogen actions. The crucial need to control and monitor plasma levels of 17β‐oestradiol calls for accurate, precise and robust assay methods. The performance of direct radioimmunoassays (RIAs) in measurement of 17β‐oestradiol has been reported previously for human samples, but to our knowledge not for rat samples. In the current study, 552 serum samples from ovx, native and hormone‐treated rats were used to compare the performance of three commercially manufactured direct RIAs from the companies DPC (Siemens Healthcare Diagnostics Inc., formerly Diagnostic Products Corporation), DSL (Diagnostic Systems Labs) and MPB (MP Biomedicals, formerly ICN Biomedicals). Substantial differences in results between the three assay methods were found when measuring serum 17β‐oestradiol concentrations. The following formulas describing the relation between the different methods were obtained using weighted Deming's orthogonal regression (based on pg/mL): DSL = 0.43*DPC+12.3, MPB = 2.1*DPC+84.7 and DSL = 4.8*MPB+22.2. Furthermore, a preceding diethyl ether extraction step of the serum appears to impair the performance of the RIAs in the present samples (based on pg/mL): DPC_ex = 0.39*DPC_unex+0.76, DSL_ex = 0.32*DSL_unex?1.7 and MPB_ex = 0.22*MPB_unex+1.4.     

Coping in relation to perceived threat of the risk of graft rejection and Health‐Related Quality of Life of organ transplant recipients

The most serious risk connected with transplantations besides infection is graft rejection. Organ transplant recipients (OTRs) perceive graft rejection as a stress factor and a threat. The primary aim of the present study was to examine types of coping used to handle the threat of the risk of graft rejection among OTRs and to investigate relations between coping and perceived threat as well as Health‐Related Quality of Life (HRQoL). A second aim was to test the General Coping Questionnaire (GCQ) for reliability in relation to the threat of the risk of graft rejection. Three different questionnaires, the Perceived Threat of the Risk of Graft Rejection (PTGR), GCQ and the SF‐36, were mailed to 229 OTRs between 19 and 65 years old. Patients were transplanted with a kidney, a liver or a heart and/or a lung. All patients with follow‐up time of 1 year ± 3 months and 3 years ± 3 months were included. With an 81% response rate, the study comprised of 185 OTRs. The differences between the transplanted organ groups in their use of coping were small. Likewise, coping related weakly with sex, age, time since transplantation and whether they had experienced graft rejections or not. The respondents tended in general to use more of the ‘positive’ coping (strategies related to positive well‐being). The measured coping in relation to the perceived threat of the risk of graft rejection seem to be relatively stable over time and quite independent of demographic and clinical variables.     

Students' and lecturers' perceptions of support in a UK pre-registration midwifery programme

This paper reports on a study that explored the perceptions of students and lecturers regarding support within a pre-registration midwifery programme in one Higher Education Institution in England. A mixed method design was used: questionnaires were completed by first year and third year students and lecturers, complemented by focus groups with each of the three sets of participants. The findings showed that there are multi-focal challenges for student midwives in undertaking their programme of study. The main theme that emerged was of the difficulties involved in maintaining an appropriate work–life balance, especially within what was seen as a relatively inflexible programme structure. The value of peer support was also highlighted as a key factor in helping the students succeed in their studies. There were a number of implications for midwifery educators to consider in optimising support for students. These include ensuring that students have realistic expectations at the outset of their studies, formalising peer support mechanisms and reviewing programmes to provide more flexibility to better underpin the maintenance of an appropriate work–life balance. Further study is warranted to explore perceptions of support in practice and to identify the factors that help students to persevere in their studies.     

Intracellular Tracking of Single-plasmid DNA Particles After Delivery by Electroporation

Electroporation is a physical method of transferring molecules into cells and tissues. It takes advantage of the transient permeabilization of the cell membrane induced by electric field pulses, which gives hydrophilic molecules access to the cytoplasm. This method offers high transfer efficiency for small molecules that freely diffuse through electrically permeabilized membranes. Larger molecules, such as plasmid DNA, face several barriers (plasma membrane, cytoplasmic crowding, and nuclear envelope), which reduce transfection efficiency and engender a complex mechanism of transfer. Our work provides insight into the way electrotransferred DNA crosses the cytoplasm to reach the nucleus. For this purpose, single-particle tracking experiments of fluorescently labeled DNA were performed. Investigations were focused on the involvement of the cytoskeleton using drugs disrupting or stabilizing actin and tubulin filaments as the two relevant cellular networks for particle transport. The analysis of 315 movies (~4,000 trajectories) reveals that DNA is actively transported through the cytoskeleton. The large number of events allows a statistical quantification of the DNA motion kinetics inside the cell. Disruption of both filament types reduces occurrence and velocities of active transport and displacements of DNA particles. Interestingly, stabilization of both networks does not enhance DNA transport.     

Associations of Pre- and Postnatal Air Pollution Exposures with Child Blood Pressure and Modification by Maternal Nutrition: A Prospective Study in the CANDLE Cohort

Background: Limited data suggest air pollution exposures may contribute to pediatric high blood pressure (HBP), a known predictor of adult cardiovascular diseases.Methods: We investigated this association in the Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) study, a sociodemographically diverse pregnancy cohort in the southern United States with participants enrolled from 2006 to 2011. We included 822 mother–child dyads with available address histories and a valid child blood pressure measurement at 4–6 y. Systolic (SBP) and diastolic blood pressures (DBP) were converted to age-, sex-, and height-specific percentiles for normal-weight U.S. children. HBP was classified based on SBP or DBP ≥90th percentile. Nitrogen dioxide (NO2) and particulate matter ≤2.5μm in aerodynamic diameter (PM2.5) estimates in both pre- and postnatal windows were obtained from annual national models and spatiotemporal models, respectively. We fit multivariate Linear and Poisson regressions and explored multiplicative joint effects with maternal nutrition, child sex, and maternal race using interaction terms.Results: Mean PM2.5 and NO2 in the prenatal period were 10.8 [standard deviation (SD): 0.9] μg/m3 and 10.0 (SD: 2.4) ppb, respectively, and 9.9 (SD: 0.6) μg/m3 and 8.8 (SD: 1.9) ppb from birth to the 4-y-old birthday. On average, SBP percentile increased by 14.6 (95% CI: 4.6, 24.6), and DBP percentile increased by 8.7 (95% CI: 1.4, 15.9) with each 2-μg/m3 increase in second-trimester PM2.5. PM2.5 averaged over the prenatal period was only significantly associated with higher DBP percentiles [β= 11.6 (95% CI: 2.9, 20.2)]. Positive associations of second-trimester PM2.5 with SBP and DBP percentiles were stronger in children with maternal folate concentrations in the lowest quartile (pinteraction= 0.05 and 0.07, respectively) and associations with DBP percentiles were stronger in female children (pinteraction= 0.05). We did not detect significant association of NO2, road proximity, and postnatal PM2.5 with any outcomes.Conclusions: The findings suggest that higher prenatal PM2.5 exposure, particularly in the second trimester, is associated with elevated early childhood blood pressure. This adverse association could be modified by pregnancy folate concentrations. https://doi.org/10.1289/EHP7486     

Phase 2 reentry in man.

BACKGROUND: Ventricular extrasystoles are characterized by a fixed coupling interval to the last QRST complex preceding it. OBJECTIVES: We hypothesized that this QRST complex differed from QRST complexes of other sinus beats not followed by ventricular extrasystoles. Further, we investigated whether phase 2 reentry, demonstrated in animal experiments to initiate ventricular extrasystoles, ventricular tachycardia, and ventricular fibrillation, also plays a role in humans. METHODS: We examined 18 patients with ventricular extrasystoles and/or ventricular tachycardia by signal averaging of the ECG (group A) or by single-beat analysis of intracardiac electrograms (group B). Group A consisted of six patients without structural heart disease and one patient with the Brugada syndrome. Six of the seven patients had right ventricular outflow tract ventricular extrasystoles. Group B consisted of 11 patients undergoing radiofrequency ablation. Eight of the 11 patients had right ventricular outflow tract extrasystoles. RESULTS: In six of the seven patients in group A, we demonstrated significant ST-elevation and/or T-wave changes in the sinus beat preceding ventricular extrasystoles compared with the second last sinus beat in one or more of the three orthogonal leads X, Y, and Z. In 9 of the 11 patients in group B, single-beat analysis of unipolar and bipolar electrograms recorded close to successful ablation sites demonstrated similar changes, that is, ST-elevation (median peak voltage gradient 150 muV, range 0-1,700) and T-wave changes in the sinus beat prior to ventricular ectopy. In addition, J-point elevation was demonstrated in several cases. In total, significant changes were demonstrated in 15 of the 18 patients studied (83%). CONCLUSION: J-point elevation, ST-elevation, and T-wave changes documented in the last sinus beat prior to ventricular extrasystoles are in agreement with phase 2 reentry, suggesting that this may be the responsible mechanism for ventricular extrasystoles and ventricular tachycardia/fibrillation. The phenomenon has been demonstrated in only animal experiments to date.     

Pneumolysin potentiates oxidative inactivation of alpha-1-proteinase inhibitor by activated human neutrophils

This study was designed to investigate the effects of the Streptococcus pneumoniae-derived, pro-inflammatory toxin, pneumolysin (8.37 and 41.75 ng/ml), on the oxidative inactivation of alpha-1-protease inhibitor (API) by chemoattractant-activated human neutrophils in vitro. The elastase inhibitory capacity (EIC) of API in supernatants from unstimulated neutrophils, neutrophils treated with pneumolysin only, or with the chemoattractant FMLP (1 microM) only, or the combination of the toxin with FMLP was measured by a colorimetric procedure based on the activity of added porcine elastase. The EIC of API was unaffected by exposure to pneumolysin only, unstimulated neutrophils, or neutrophils treated with pneumolysin only. However, exposure to FMLP-activated neutrophils resulted in a reduction of the EIC of API, which was significantly (P<0.05) augmented by pneumolysin (mean reductions of 16%, 43% and 83% for FMLP only and in combination with 8.37 and 41.75 ng/ml pneumolysin, respectively), and was attenuated by wortmannin (1 microM), an inhibitor of NADPH oxidase, the oxidant-scavenger methionine (100 microM), and depletion of Ca2+ from the cell-suspending medium. These pro-proteolytic interactions of pneumolysin with chemoattractant-activated neutrophils may contribute to the invasiveness of the pneumococcus.