218 research outputs found

    Regio- and stereoselective steroid hydroxylation by CYP109A2 from Bacillus megaterium explored by X-ray crystallography and computational modeling

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    The P450 monooxygenase CYP109A2 from Bacillus megaterium DSM319 was previously found to convert vitamin D3 to 25-hydroxyvitamin D3. Here, we show that this enzyme is also able to convert testosterone in a highly regio- and stereoselective manner to 16β-hydroxytestosterone. To reveal the structural determinants governing the regio- and stereoselective steroid hydroxylation reactions catalyzed by CYP109A2, two crystal structures of CYP109A2 were solved in similar closed conformations, one revealing a bound testosterone in the active site pocket, albeit at a non-productive site away from the heme-iron. To examine if the closed crystal structures nevertheless correspond to a reactive conformation of CYP109A2, docking and molecular dynamics simulations were performed with testosterone and vitamin D3 present in the active site. These molecular dynamics simulations were analyzed for catalytically productive conformations, the relative occurrences of which were in agreement with the experimentally determined stereoselectivities if the predicted stability of each carbon hydrogen bond was taken into account. Overall, the first-time determination and analysis of the catalytically relevant 3D conformation of CYP109A2 will allow for future small molecule ligand screening in silico, as well as enabling site-directed mutagenesis towards improved enzymatic properties of this enzyme.</p

    Real-time conformational changes and controlled orientation of native proteins inside a protein nanoreactor

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    Protein conformations play crucial roles in most, if not all, biological processes. Here we show that the current carried through a nanopore by ions allows monitoring conformational changes of single and native substrate-binding domains (SBD) of an ATP-Binding Cassette importer in real-time. Comparison with single-molecule Förster Resonance Energy Transfer and ensemble measurements revealed that proteins trapped inside the nanopore have bulk-like properties. Two ligand-free and two ligand-bound conformations of SBD proteins were inferred and their kinetic constants were determined. Remarkably, internalized proteins aligned with the applied voltage bias, and their orientation could be controlled by the addition of a single charge to the protein surface. Nanopores can thus be used to immobilize proteins on a surface with a specific orientation, and will be employed as nanoreactors for single-molecule studies of native proteins. Moreover, nanopores with internal protein adaptors might find further practical applications in multianalyte sensing devices

    Experiences of non-progressive and augmented labour among nulliparous women: a qualitative interview study in a Grounded Theory approach

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    <p>Abstract</p> <p>Background</p> <p>Non-progressive labour is the most common complication in nulliparas and is primarily treated by augmentation. Augmented labour is often terminated by instrumental delivery. Little qualitative research has addressed experiences of non-progressive and augmented deliveries. The aim of this study was to gain a deeper understanding of the experience of non-progressive and augmented labour among nulliparas and their experience of the care they received.</p> <p>Methods</p> <p>A qualitative study was conducted using individual interviews. Data was collected and analysed according to the Grounded Theory method. The participants were a purposive sample of ten women. The interviews were conducted 4–15 weeks after delivery.</p> <p>Results</p> <p>The women had contrasting experiences during the birth process. During labour there was a conflict between the expectation of having a natural delivery and actually having a medical delivery. The women experienced a feeling of separation between mind and body. Interacting with the midwife had a major influence on feelings of losing and regaining control. Reconciliation between the contrasting feelings during labour was achieved. The core category was named Dialectical Birth Process and comprised three categories: Balancing natural and medical delivery, Interacting, Losing and regaining control.</p> <p>Conclusion</p> <p>A dialectical process was identified in these women's experiences of non-progressive labour. The process is susceptible to interaction with the midwife; especially her support to the woman's feeling of being in control. Midwives should secure that the woman's recognition of the fact that the labour is non-progressive and augmentation is required is handled with respect for the dialectical process. Augmentation of labour should be managed as close to the course of natural labour and delivery as possible.</p

    Pipamperone Population Pharmacokinetics Related to Effectiveness and Side Effects in Children and Adolescents

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    Background: Pipamperone is a frequently prescribed antipsychotic in children and adolescents in the Netherlands, Belgium, and Germany. However, pediatric pharmacokinetics and the relationship with side effects and efficacy are unknown. Currently, divergent pediatric dosing recommendations exist. Objectives: The objective of this study was to describe the population pharmacokinetics of pipamperone in children and adolescents; to correlate measured and predicted pipamperone trough concentrations and predicted 24-h area under the curves with effectiveness, extrapyramidal symptoms, and sedation; and to propose dose recommendations based on simulations. Methods: Pipamperone concentrations were collected from Dutch pediatric patients in a prospective naturalistic trial (n = 8), and German pediatric patients in a therapeutic drug monitoring service (n = 22). A total of 70 pipamperone concentrations were used to develop a population pharmacokinetic model with non-linear mixed-effects modeling (NONMEM®). Additionally, an additional random sample of 21 German patients with 33 pipamperone concentrations from the same therapeutic drug monitoring service was used for external validation. Pharmacokinetic parameters were related to clinical improvement, sedation, and extrapyramidal symptoms. Simulations were performed to determine optimal dosages. Results: In a one-compartment model, the apparent volume of distribution was 416 L/70 kg and the apparent clearance was 22.1 L/h/70 kg. Allometric scaling was used to correct for differences in bodyweight. The model was successfully externally validated. The median [25th–75th percentile] measured pipamperone trough concentrations were numerically higher in responders (98.0 µg/L [56.0–180.5 µg/L]) than in non-responders (58.0 µg/L [14.9–105.5 µg/L]), although non-significant (p = 0.14). A twice-daily 0.6-mg/kg dosage was better than a fixed dosage to attain the concentration range observed in responders. Conclusions: Our findings suggest that pipamperone therapeutic reference ranges may be lower for children with behavioral problems than recommended for adults with psychotic symptoms (100–400 µg/L). When dosing pipamperone in children and adolescents, bodyweight should be taken into account

    Assessment of social psychological determinants of satisfaction with childbirth in a cross-national perspective

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    <p>Abstract</p> <p>Background</p> <p>The fulfilment of expectations, labour pain, personal control and self-efficacy determine the postpartum evaluation of birth. However, researchers have seldom considered the multiple determinants in one analysis. To explore to what extent the results can be generalised between countries, we analyse data of Belgian and Dutch women. Although Belgium and the Netherlands share the same language, geography and political system and have a common history, their health care systems diverge. The Belgian maternity care system corresponds to the ideal type of the medical model, whereas the Dutch system approaches the midwifery model. In this paper we examine multiple determinants, the fulfilment of expectations, labour pain, personal control and self-efficacy, for their association with satisfaction with childbirth in a cross-national perspective.</p> <p>Methods</p> <p>Two questionnaires were filled out by 605 women, one at 30 weeks of pregnancy and one within the first 2 weeks after childbirth either at home or in a hospital. Of these, 560 questionnaires were usable for analysis. Women were invited to participate in the study by independent midwives and obstetricians during antenatal visits in 2004–2005. Satisfaction with childbirth was measured by the Mackey Satisfaction with Childbirth Rating Scale, which takes into account the multidimensional nature of the concept. Labour pain was rated retrospectively using Visual Analogue Scales. Personal control was assessed with the Wijma Delivery Expectancy/Experience Questionnaire and Pearlin and Schooler's mastery scale. A hierarchical linear analysis was performed.</p> <p>Results</p> <p>Satisfaction with childbirth benefited most consistently from the fulfilment of expectations. In addition, the experience of personal control buffered the lowering impact of labour pain. Women with high self-efficacy showed more satisfaction with self-, midwife- and physician-related aspects of the birth experience.</p> <p>Conclusion</p> <p>Our findings focus the attention toward personal control, self-efficacy and expectations about childbirth. This study confirms the multidimensionality of childbirth satisfaction and demonstrates that different factors predict the various dimensions of satisfaction. The model applies to both Belgian and Dutch women. Cross-national comparative research should further assess the dependence of the determinants of childbirth satisfaction on the organisation of maternity care.</p

    Exercise Training in Pregnancy for obese women (ETIP): study protocol for a randomised controlled trial

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    <p/> <p>Background</p> <p>Both maternal pre-pregnancy obesity and excessive gestational weight gain are increasing in prevalence and associated with a number of adverse pregnancy outcomes for both mother and child. Observational studies regarding physical activity in pregnancy have found reduced weight gain in active mothers, as well as reduced risk of adverse pregnancy outcomes. There is however a lack of high quality, randomized controlled trials on the effects of regular exercise training in pregnancy, especially those with a pre-pregnancy body mass index (BMI) at or above 30 kg/m<sup>2</sup>.</p> <p>Methods</p> <p>We are conducting a randomised, controlled trial in Norway with two parallel arms; one intervention group and one control group. We will enroll 150 previously sedentary, pregnant women with a pre-pregnancy BMI at or above 30 kg/m<sup>2</sup>. The intervention group will meet for organized exercise training three times per week, starting in gestation week 14 (range 12-16). The control group will get standard antenatal care. The main outcome measure will be weight gain from baseline to delivery. Among the secondary outcome measures are changes in exercise capacity, endothelial function, physical activity level, body composition, serum markers of cardiovascular risk, incontinence, lumbopelvic pain and cardiac function from baseline to gestation week 37 (range 36-38). Offspring outcome measures include anthropometric variables at birth, Apgar score, as well as serum markers of inflammation and metabolism in cord blood.</p> <p>Discussion</p> <p>The results of this trial will provide knowledge about effects of regular exercise training in previously sedentary, obese pregnant women. If the program proves effective in reducing gestational weight gain and adverse pregnancy outcomes, such programs should be considered as part of routine pregnancy care for obese women.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01243554">NCT01243554</a></p

    Establishing a valid construct of fear of childbirth: Findings from in-depth interviews with women and midwives

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    Background: Fear of childbirth (FOC) can have a negative impact on a woman’s psychological wellbeing during pregnancy and her experience of birth. It has also been associated with adverse obstetric outcomes and postpartum mental health difficulties. However the FOC construct is itself poorly defined. This study aimed to systematically identify the key elements of FOC as reported by women themselves. Methods: Semi-structured interviews with pregnant women (n= 10) who reported to be fearful of childbirth and telephone interviews with consultant midwives (n= 13) who regularly work with women who are fearful of childbirth were conducted. Interviews were analysed using thematic analysis for each group independently to provide two sources of information. Findings were reviewed in conjunction with a third source, a recently published meta-synthesis of existing literature of women’s own accounts of FOC. The key elements of FOC were determined via presence in two out of the three sources at least one of which was from women themselves, i.e. the reports of the women interviewed or the meta-synthesis. Results: Seven themes were identified by the women and the consultant midwives: Fear of not knowing and not being able to plan for the unpredictable, Fear of harm or stress to the baby, Fear of inability to cope with the pain, Fear of harm to self in labour and postnatally, Fear of being ‘done to’, Fear of not having a voice in decision making and Fear of being abandoned and alone. One further theme was generated by the women and supported by the reports included the meta-synthesis: Fear about my body’s ability to give birth. Two further themes were generated by the consultant midwives and were present also in the meta synthesis: Fear of internal loss of control and Terrified of birth and not knowing why. Conclusions: Ten key elements in women’s FOC were identified. These can now be used to inform development of measurement tools with verified content validity to identify women experiencing FOC, to support timely access to support during pregnancy
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