137 research outputs found

    A High Pressure Distorted a-Uranium (Pnma) Structure in Plutonium

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    Under pressure many rare earths and actinide metals transform to a-U structure or its lower symmetry distorted forms. We have reinterpreted the diffraction data of Dabos et al for Pu (reference 4) and find that a Am IV type distorted a-U structure in Pnma space group can explain this for its high pressure phase. The structures of this phase and a-Pu are both shown to have a distorted hcp topology. The upturn in the atomic volume of Pu at 0.1 MPa can also be rationalized on the basis of this proposalComment: 10pages,3 figure

    Understanding the complex phase diagram of uranium: the role of electron-phonon coupling

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    We report an experimental determination of the dispersion of the soft phonon mode along [1,0,0] in uranium as a function of pressure. The energies of these phonons increase rapidly, with conventional behavior found by 20 GPa, as predicted by recent theory. New calculations demonstrate the strong pressure (and momentum) dependence of the electron-phonon coupling, whereas the Fermi-surface nesting is surprisingly independent of pressure. This allows a full understanding of the complex phase diagram of uranium, and the interplay between the charge-density wave and superconductivity

    Advanced paternal age is associated with an increased risk of spontaneous miscarriage: a systematic review and meta-analysis

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    BACKGROUND: Although spontaneous miscarriage is the most common complication of human pregnancy, potential contributing factors are not fully understood. Advanced maternal age has long been recognised as a major risk factor for miscarriage, being strongly related with fetal chromosomal abnormalities. The relation between paternal age and the risk of miscarriage is less evident, yet it is biologically plausible that an increasing number of genetic and epigenetic sperm abnormalities in older males may contribute to miscarriage. Previous meta-analyses showed associations between advanced paternal age and a broad spectrum of perinatal and paediatric outcomes. This is the first systematic review and meta-analysis on paternal age and spontaneous miscarriage.OBJECTIVE AND RATIONALE: The aim of this systematic review and meta-analysis is to evaluate the effect of paternal age on the risk of spontaneous miscarriage.SEARCH METHODS: PubMed, Embase and Cochrane databases were searched to identify relevant studies up to August 2019. The following free text and MeSH terms were used: paternal age, father's age, male age, husband's age, spontaneous abortion, spontaneous miscarriage, abortion, miscarriage, pregnancy loss, fetal loss and fetal death. PRISMA guidelines for systematic reviews and meta-analysis were followed. Original research articles in English language addressing the relation between paternal age and spontaneous miscarriage were included. Exclusion criteria were studies that solely focused on pregnancy outcomes following artificial reproductive technology (ART) and studies that did not adjust their effect estimates for at least maternal age. Risk of bias was qualitatively described for three domains: bias due to confounding, information bias and selection bias.OUTCOMES: The search resulted in 975 original articles. Ten studies met the inclusion criteria and were included in the qualitative synthesis. Nine of these studies were included in the quantitative synthesis (meta-analysis). Advanced paternal age was found to be associated with an increased risk of miscarriage. Pooled risk estimates for miscarriage for age categories 30-34, 35-39, 40-44 and >= 45 years of age were 1.04 (95% CI 0.90, 1.21), 1.15 (0.92, 1.43), 1.23 (1.06, 1.43) and 1.43 (1.13, 1.81) respectively (reference category 25-29 years). A second meta-analysis was performed for the subgroup of studies investigating first trimester miscarriage. This showed similar pooled risk estimates for the first three age categories and a slightly higher pooled risk estimate for age category >= 45 years (1.74; 95% CI 1.26, 2.41).WIDER IMPLICATIONS: Over the last decades, childbearing at later ages has become more common. It is known that frequencies of adverse reproductive outcomes, including spontaneous miscarriage, are higher in women with advanced age. We show that advanced paternal age is also associated with an increased risk of spontaneous miscarriage. Although the paternal age effect is less pronounced than that observed with advanced maternal age and residual confounding by maternal age cannot be excluded, it may have implications for preconception counselling of couples comprising an older aged male.Cervix cance

    Exploring gender differences among couples with unexplained recurrent pregnancy loss regarding preferences for supportive care

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    Background International guidelines recommend to offer supportive care during a next pregnancy to couples affected by recurrent pregnancy loss (RPL). In previous research, several options for supportive care have been identified and women's preferences have been quantified. Although it is known that RPL impacts the mental health of both partners, male preferences for supportive care have hardly been explored. Methods A cross-sectional study was conducted in couples who visited a specialized RPL clinic in the Netherlands between November 2018 and December 2019. Both members of the couples received a questionnaire that quantified their preferences for supportive care in a next pregnancy and they were asked to complete this independently from each other. Preferences for each supportive care option were analysed on a group level (by gender) and on a couple level, by comparing preferences of both partners. Results Ninety-two questionnaires (completed by 46 couples) were analysed. The overall need for supportive care indicated on a scale from 1 to 10 was 6.8 for men and 7.9 for women (P = 0.002). Both genders preferred to regularly see the same doctor with knowledge of their obstetric history, to make a plan for the first trimester and to have frequent ultrasound examinations. A lower proportion of men preferred a doctor that shows understanding (80% of men vs. 100% of women, P = 0.004) and a doctor that informs on wellbeing (72% vs. 100%, P = <= 0.000). Fewer men preferred support from friends (48% vs. 74%, P = 0.017). Thirty-seven percent of men requested more involvement of the male partner at the outpatient clinic, compared to 70% of women (P = 0.007). In 28% of couples, partners had opposing preferences regarding peer support. Conclusions While both women and men affected by RPL are in need of supportive care, their preferences may differ. Current supportive care services may not entirely address the needs of men. Health care professionals should focus on both partners and development of novel supportive care programs with specific attention for men should be considered.Gynecolog

    Impaired immunomodulatory effects of seminal plasma may play a role in unexplained recurrent pregnancy loss: results of an in vitro study

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    Background: Seminal plasma contains signaling molecules capable of modulating the maternal immune environment to support implantation and pregnancy. Prior studies indicated that seminal plasma induces changes in gene transcription of maternal immune cells. Reduced immune suppressive capacity may lead to pregnancy loss. The aim of this study was to investigate the immunomodulating effects of seminal plasma on T cells and monocytes in the context of recurrent pregnancy loss (RPL).Methods: Female T cells and monocytes were incubated with seminal plasma of 20 males in unexplained RPL couples (RPL males) and of 11 males whose partners had ongoing pregnancies (control males). The effect of seminal plasma on messenger RNA (mRNA) expression of immune cells was measured. Levels of mRNA expression were related to key signaling molecules present in the seminal plasma. Agglomerative hierarchical cluster analysis was performed on seminal plasma expression profiles and on mRNA expression profiles. Results: Expression of CD25 and anti-inflammatory IL-10 by female T cells was significantly lower after stimulation with seminal plasma of RPL males compared to control males. Female monocytes treated with seminal plasma of RPL males showed an immune activation signature of relatively elevated HLA-DR expression. Expression of these T cell and monocyte components was particularly correlated with the amounts of TGF-beta and VEGF in the seminal plasma. Conclusion: Our findings indicate that seminal plasma has immunomodulating properties on female immune cells compatible with the induction of a more regulatory phenotype, which may be impaired in cases of unexplained RPL.Clinical epidemiolog

    Identification of distinct seminal plasma cytokine profiles associated with male age and lifestyle characteristics in unexplained recurrent pregnancy loss

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    Background: Seminal plasma contains a wide range of cytokines, chemokines and growth factors. Part of these signalling molecules assist in inducing a state of active maternal immune tolerance towards the fetus. Disbalances in seminal plasma content may contribute to pregnancy loss. This study investigated cytokine expression profiles in seminal plasma of male partners of couples with unexplained recurrent pregnancy loss (RPL) and the association with clinical and lifestyle characteristics, including smoking, alcohol consumption and body mass index (BMI). Methods: In the seminal plasma of 52 men who visited a specialised RPL clinic the levels of 25 pre-selected cytokines, chemokines and growth factors were measured by Bio-Plex assay or ELISA. Two-way hierarchical cluster analysis was performed. Identified patient clusters were compared on clinical and lifestyle characteristics. Results: Two distinct cytokine expression profiles in the seminal plasma were revealed by cluster analysis. Patient cluster I showed relatively higher levels of pro-inflammatory cytokines, including IL-1 alpha, IL-1 beta, IL-6, IL-8, IL-12, IL-18 and TNF-alpha, compared to Patient cluster II. Men belonging to Patient cluster I were significantly older and had significantly more lifestyle risk factors compared to men in Patient cluster II. Conclusion: Cluster analysis suggested the existence of a less favourable pro-inflammatory cytokine expression profile, being present in part of men affected by RPL and associated with advanced male age and lifestyle risk factors. These findings may serve as a starting point for further research into underlying mechanisms and ultimately lead to novel diagnostic and therapeutic approaches for couples with RPL.Research into fetal development and medicin

    Evaluating the role of paternal factors in aetiology and prognosis of recurrent pregnancy loss: Study protocol for a hospital-based multicentre case-control study and cohort study (REMI III project)

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    Introduction Recurrent pregnancy loss (RPL) is defined as the spontaneous demise of two or more pregnancies before the fetus reaches viability. Despite investigation of multiple known maternal risk factors, in more than 50% of couples, this condition remains unexplained. Studies focusing on paternal factors in RPL are scarce, and therefore, paternal evaluation in RPL is currently very limited. However, regarding single miscarriage, there are multiple publications suggesting a contributive role of paternal factors. In this project, we aim to identify paternal factors associated with RPL and to improve couple-specific prediction of future pregnancy outcomes by developing a prediction model containing both maternal and paternal factors. Methods and analysis In a case-control design, the relation between unexplained RPL and paternal age, lifestyle factors, sperm DNA damage and immunomodulatory factors in peripheral blood and semen will be studied. Prospectively, 135 couples with naturally conceived unexplained RPL (cases) and 135 fertile couples without a history of pregnancy loss (controls) will be included, with collection of paternal blood and semen samples and documentation of clinical and lifestyle characteristics. In addition, 600 couples from both groups will be included retrospectively. To adjust for confounders, multivariate logistic regression will be used. The predictive value of paternal and maternal factors will be studied in the total RPL cohort consisting of approximately 735 couples. The primary outcome of the cohort study is live birth within 5 years after initial visit of the clinic. Secondary outcomes are ongoing pregnancy, time interval until next pregnancy and pregnancy complications. Ethics and dissemination This project is approved by the Medical Research Ethics Committee

    Frontotemporal dementia with the C9ORF72 hexanucleotide repeat expansion: clinical, neuroanatomical and neuropathological features

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    An expanded hexanucleotide repeat in the C9ORF72 gene has recently been identified as a major cause of familial frontotemporal lobar degeneration and motor neuron disease, including cases previously identified as linked to chromosome 9. Here we present a detailed retrospective clinical, neuroimaging and histopathological analysis of a C9ORF72 mutation case series in relation to other forms of genetically determined frontotemporal lobar degeneration ascertained at a specialist centre. Eighteen probands (19 cases in total) were identified, representing 35% of frontotemporal lobar degeneration cases with identified mutations, 36% of cases with clinical evidence of motor neuron disease and 7% of the entire cohort. Thirty-three per cent of these C9ORF72 cases had no identified relevant family history. Families showed wide variation in clinical onset (43ā€“68 years) and duration (1.7ā€“22 years). The most common presenting syndrome (comprising a half of cases) was behavioural variant frontotemporal dementia, however, there was substantial clinical heterogeneity across the C9ORF72 mutation cohort. Sixty per cent of cases developed clinical features consistent with motor neuron disease during the period of follow-up. Anxiety and agitation and memory impairment were prominent features (between a half to two-thirds of cases), and dominant parietal dysfunction was also frequent. Affected individuals showed variable magnetic resonance imaging findings; however, relative to healthy controls, the group as a whole showed extensive thinning of frontal, temporal and parietal cortices, subcortical grey matter atrophy including thalamus and cerebellum and involvement of long intrahemispheric, commissural and corticospinal tracts. The neuroimaging profile of the C9ORF72 expansion was significantly more symmetrical than progranulin mutations with significantly less temporal lobe involvement than microtubule-associated protein tau mutations. Neuropathological examination in six cases with C9ORF72 mutation from the frontotemporal lobar degeneration series identified histomorphological features consistent with either type A or B TAR DNA-binding protein-43 deposition; however, p62-positive (in excess of TAR DNA-binding protein-43 positive) neuronal cytoplasmic inclusions in hippocampus and cerebellum were a consistent feature of these cases, in contrast to the similar frequency of p62 and TAR DNA-binding protein-43 deposition in 53 control cases with frontotemporal lobar degenerationā€“TAR DNA-binding protein. These findings corroborate the clinical importance of the C9ORF72 mutation in frontotemporal lobar degeneration, delineate phenotypic and neuropathological features that could help to guide genetic testing, and suggest hypotheses for elucidating the neurobiology of a culprit subcortical network
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