Experiments on the effect of tropical Atlantic heating anomalies upon GCM rain forecasts over the Americas

A series of real data experiments is performed with a general circulation model in order to ascertain the sensitivity of extended range rain forecasts over the Americas to the structure and magnitude of tropical heating anomalies. The emphasis is upon heat inputs over the tropical Atlantic which have shown particularly significant drying influences over North America in our prior simulations. The heating imposed in the prior experiments is compared to the condensation heating rates that naturally occur in the forecast model, and shown to be excessive by approximately a factor of two. Present experiments reduce the imposed anomaly by a factor of three, and also incorporate sea-surface temperature decreases over the eastern tropical Pacific Ocean. The new experimental results are in many ways consistent with our prior results. The dry North American response is statistically more significant than the South American response, and occurs at least as frequently in the different members of the experimental ensembles as in our prior experiments. The drying effect is accentuated by the presence of East Pacific cooling, but this does not appear to be the dominant influence. Over tropical South America, the Pacific and Atlantic modifications produce compensating influences, with the former dominating dominant, and allowing increased rainfall over the Amazon Basin.A series of real data experiments is performed with a general circulation model in order to ascertain the sensitivity of extended range rain forecasts over the Americas to the structure and magnitude of tropical heating anomalies. The emphasis is upon heat inputs over the tropical Atlantic which have shown particularly significant drying influences over North America in our prior simulations. The heating imposed in the prior experiments is compared to the condensation heating rates that naturally occur in the forecast model, and shown to be excessive by approximately a factor of two. Present experiments reduce the imposed anomaly by a factor of three, and also incorporate sea-surface temperature decreases over the eastern tropical Pacific Ocean. The new experimental results are in many ways consistent with our prior results. The dry North American response is statistically more significant than the South American response, and occurs at least as frequently in the different members of the experimental ensembles as in our prior experiments. The drying effect is accentuated by the presence of East Pacific cooling, but this does not appear to be the dominant influence. Over tropical South America, the Pacific and Atlantic modifications produce compensating influences, with the former dominating dominant, and allowing increased rainfall over the Amazon Basin

Applying torque to the Escherichia coli flagellar motor using magnetic tweezers

The bacterial flagellar motor of Escherichia coli is a nanoscale rotary engine essential for bacterial propulsion. Studies on the power output of single motors rely on the measurement of motor torque and rotation under external load. Here, we investigate the use of magnetic tweezers, which in principle allow the application and active control of a calibrated load torque, to study single flagellar motors in Escherichia coli. We manipulate the external load on the motor by adjusting the magnetic field experienced by a magnetic bead linked to the motor, and we probe the motor's response. A simple model describes the average motor speed over the entire range of applied fields. We extract the motor torque at stall and find it to be similar to the motor torque at drag-limited speed. In addition, use of the magnetic tweezers allows us to force motor rotation in both forward and backward directions. We monitor the motor's performance before and after periods of forced rotation and observe no destructive effects on the motor. Our experiments show how magnetic tweezers can provide active and fast control of the external load while also exposing remaining challenges in calibration. Through their non-invasive character and straightforward parallelization, magnetic tweezers provide an attractive platform to study nanoscale rotary motors at the single-motor level

Further experiments on the effect of tropical atlantic heating anomalies upon GCM rain forecasts over the americas

Abstrac

Attitudes towards the implementation of universal umbilical artery lactate analysis in a South African district hospital

BACKGROUND : Of the 5.54 million stillbirths and neonatal deaths occurring globally each year, a significant amount of these occur in the setting of inadequate intrapartum care. The introduction of universal umbilical artery lactate (UA) measurements in this setting may improve outcomes by providing an objective measurement of quality of care and stimulating case reflection, audit, and practice change. It is important that consideration is given to the barriers and facilitators to implementing this tool outside of a research setting. METHODS : During the period 16/11/2014 -13/01/2015, we conducted a training course in cardiotocograph (CTG) interpretation, fetal physiology, and the sampling and analysing of UA lactate, with a pre and post questionnaire aimed at assessing the barriers and facilitators to the introduction of universal UA lactate in a district hospital in the Eastern Cape, South Africa. RESULTS : Thirty-five pre-training questionnaires available (overall response rate 95 %) and 22 post training questionnaires (response rate 63 %) were available for analysis. Prior to training, the majority gave positive responses (strongly agree or agree) that measuring UA lactate assists neonatal care, is protective for staff medicolegally, and improves opportunities for audit and teaching of maternity practice (n = 33, 30, 32; 94.4 %, 85.7 %, 91.4 % respectively). Respondents remained positive about the benefits post training. An increased workload on medical or midwifery staff was less likely to be seen as barrier following training (71 vs. 38.9 % positive response, p = 0.038). A higher rate of respondents felt that expense and lack of equipment were likely to be barriers after completing training, although this wasn’t significant. There was a trend towards lack of time and expertise being less likely to be seen as barriers post training. CONCLUSION : The majority of participants providing intrapartum care in this setting are positive about the role of universal UA lactate analysis and the potential benefits it provides. Training aids in overcoming some of the perceived barriers to implementation of universal UA lactate analysis.Emma Allanson is a PhD candidate funded by the University of Western Australia with an Australian post-graduate award, and an Athelstan and Amy Saw Medical top-up scholarship, and by the Women and Infants Research Foundation with a Gordon King doctor of philosophy scholarship.http://www.biomedcentral.com/bmcpregnancychildbirtham2016Obstetrics and Gynaecolog

Impact of maternal HIV on umbilical cord lactate measurement at delivery in a South African labor ward

OBJECTIVE : To assess umbilical artery lactate levels and perinatal outcomes among women with and without HIV infection. METHODS : The present prospective cohort study recruited women planning to undergo vaginal delivery at Kalafong Hospital, South Africa, between March 3 and November 12, 2014. Umbilical artery lactate levels were measured and perinatal outcome data were recorded. Outcome analyses were stratified by maternal HIV status, and a subgroup analysis was performed where women with a CD4 count below 350 × 106 cells/L were compared with women without HIV. RESULTS : In total, 936 women with singleton fetuses were enrolled. Maternal HIV status was available for 897 (95.8%) participants, of whom 202 (21.6%) had HIV infections. Overall, 186 (92.1%) women with HIV infections received prophylaxis or treatment. There was no difference between participants with and without HIV infections in the preterm delivery rate (P=0.770), mode of delivery (P=0.354), neonatal resuscitation rate (P=0.717), 1‐ or 5‐minute Apgar scores below 7 (P=0.353), or the rate of having an umbilical artery lactate level above 5.45 mmol/L (P=0.301). Similarly, there were no differences in outcomes in the subgroup analysis of women with a CD4 count below 350 × 106 cells/L. CONCLUSION : Umbilical artery lactate levels and perinatal outcomes were found to be comparable between patients with and without HIV infections in a South African setting.University of Western Australia; Women and Infants Research Foundationhttp://wileyonlinelibrary.com/journal/ijgo2019-06-01hj2018Obstetrics and Gynaecolog

Molecular mechanism of Ena/VASP-mediated actin-filament elongation

Ena/VASP proteins have important functions in actin-dependent processes. A model for the actin elongation activity of Ena/VASP based on the affinity and saturation state of WH2-domain-mediated actin monomer binding is presented

Maternal super-obesity and perinatal outcomes in Australia: A national population-based cohort study

© 2015 Sullivan et al. Background: Super-obesity is associated with significantly elevated rates of obstetric complications, adverse perinatal outcomes and interventions. The purpose of this study was to determine the prevalence, risk factors, management and perinatal outcomes of super-obese women giving birth in Australia. Methods: A national population-based cohort study. Super-obese pregnant women (body mass index (BMI) >50 kg/m2 or weight >140 kg) who gave birth between January 1 and October 31, 2010 and a comparison cohort were identified using the Australasian Maternity Outcomes Surveillance System (AMOSS). Outcomes included maternal and perinatal morbidity and mortality. Prevalence estimates calculated with 95 % confidence intervals (CIs). Adjusted odds ratios (ORs) were calculated using multivariable logistic regression. Results: 370 super-obese women with a median BMI of 52.8 kg/m2 (range 40.9-79.9 kg/m2) and prevalence of 2.1 per 1 000 women giving birth (95 % CI: 1.96-2.40). Super-obese women were significantly more likely to be public patients (96.2 %), smoke (23.8 %) and be socio-economically disadvantaged (36.2 %). Compared with other women, super-obese women had a significantly higher risk for obstetric (adjusted odds ratio (AOR) 2.42, 95 % CI: 1.77-3.29) and medical (AOR: 2.89, 95 % CI: 2.64-4.11) complications during pregnancy, birth by caesarean section (51.6 %) and admission to special care (HDU/ICU) (6.2 %). The 372 babies born to 365 super-obese women with outcomes known had significantly higher rates of birthweight ≥4500 g (AOR 19.94, 95 % CI: 6.81-58.36), hospital transfer (AOR 3.81, 95 % CI: 1.93-7.55) and admission to Neonatal Intensive Care Unit (NICU) (AOR 1.83, 95 % CI: 1.27-2.65) compared to babies of the comparison group, but not prematurity (10.5 % versus 9.2 %) or perinatal mortality (11.0 (95 % CI: 4.3-28.0) versus 6.6 (95 % CI: 2.6- 16.8) per 1 000 singleton births). Conclusions: Super-obesity in pregnancy in Australia is associated with increased rates of pregnancy and birth complications, and with social disadvantage. There is an urgent need to further address risk factors leading to super-obesity among pregnant women and for maternity services to better address pre-pregnancy and pregnancy care to reduce associated inequalities in perinatal outcomes

NNT pseudoexon activation as a novel mechanism for disease in two siblings with familial glucocorticoid deficiency

CONTEXT: Intronic DNA frequently encodes potential exonic sequences called pseudoexons. In recent years, mutations resulting in aberrant pseudoexon inclusion have been increasingly recognized to cause disease. OBJECTIVES: To find the genetic cause of familial glucocorticoid deficiency (FGD) in two siblings. PATIENTS: The proband and his affected sibling, from nonconsanguineous parents of East Asian and South African origin, were diagnosed with FGD at the ages of 21 and 8 months, respectively. DESIGN: Whole exome sequencing was performed on genomic DNA (gDNA) of the siblings. Variants in genes known to cause FGD were assessed for causality. Further analysis of gDNA and cDNA was performed by PCR/RT-PCR followed by automated Sanger sequencing. RESULTS: Whole exome sequencing identified a single, novel heterozygous variant (p.Arg71*) in nicotinamide nucleotide transhydrogenase (NNT) in both affected individuals. Follow-up cDNA analysis in the proband identified a 69-bp pseudoexon inclusion event, and Sanger sequencing of his gDNA identified a 4-bp duplication responsible for its activation. The variants segregated with the disease: p.Arg71* was inherited from the mother, the pseudoexon change was inherited from the father, and an unaffected sibling had inherited only the p.Arg71* variant. CONCLUSIONS: FGD in these siblings is caused by compound heterozygous mutations in NNT; one causing pseudoexon inclusion in combination with another leading to Arg71*. Discovery of this pseudoexon activation mutation highlights the importance of identifying sequence changes in introns by cDNA analysis. The clinical implications of these findings include: facilitation of antenatal genetic diagnosis, early institution of potentially lifesaving therapy, and the possibility of preventative or curative interventio