Directional dark field retrieval with single-grid x-ray imaging

Directional dark-field imaging is an emerging x-ray modality that is sensitive to unresolved anisotropic scattering from sub-pixel sample microstructures. A single-grid imaging set-up can be used to capture dark-field images by looking at changes in a grid pattern projected upon the sample. By creating analytical models for the experiment, we have developed a single-grid directional dark field retrieval algorithm that can extract dark-field parameters such as the dominant scattering direction, and the semi-major and -minor scattering angles. We show that this method is effective even in the presence of high image noise, allowing for low dose and time sequence imaging

‘What are you going to do, confiscate their passports?’ Professional perspectives on cross-border reproductive travel

Objective: This article reports findings from a UK-based study which explored the phenomenon of overseas travel for fertility treatment. The first phase of this project aimed to explore how infertility clinicians and others professionally involved in fertility treatment understand the nature and consequences of cross-border reproductive travel. Background: There are indications that, for a variety of reasons, people from the UK are increasingly travelling across national borders to access assisted reproductive technologies. While research with patients is growing, little is known about how ‘fertility tourism’ is perceived by health professionals and others with a close association with infertility patients. Methods: Using an interpretivist approach, this exploratory research included focussed discussions with 20 people professionally knowledgeable about patients who had either been abroad or were considering having treatment outside the UK. Semi-structured interviews were recorded, transcribed verbatim and subjected to a thematic analysis. Results: Three conceptual categories are developed from the data: ‘the autonomous patient’; ‘cross-border travel as risk’, and ‘professional responsibilities in harm minimisation’. Professionals construct nuanced, complex and sometimes contradictory narratives of the ‘fertility traveller’, as vulnerable and knowledgeable; as engaged in risky behaviour and in its active minimisation. Conclusions: There is little support for the suggestion that states should seek to prevent cross-border treatment. Rather, an argument is made for less direct strategies to safeguard patient interests. Further research is required to assess the impact of professional views and actions on patient choices and patient experiences of treatment, before, during and after travelling abroad

Experiences and attitudes of Danish men who were sperm donors more than 10 years ago; a qualitative interview study

Background More knowledge about the long-term impact of sperm donation is essential as the donor’s attitude towards donation may change over time. Personal and social developments may prompt a rethinking of previous actions and decisions, or even regret. Thus, the aim of this study was to explore the experiences and attitudes of men who were sperm donors more than 10 years ago. Methods From May to September 2021, semi-structured, qualitative interviews were conducted with 23 former donors (> 10 years since last donation) from Cryos International sperm bank. Two participants were non-anonymous donors and 21 were anonymous. The interviews were conducted by phone or via video (mean 24 minutes). All interviews were recorded, transcribed verbatim and rendered anonymous. Data were analyzed using thematic analysis. Results The analysis showed that most men had been donors for monetary and altruistic purposes, and now considered sperm donation as a closed chapter that was ’unproblematic and in the past’. Most men valued anonymity and emphasized the non-relatedness between donor and donor conceived offspring. Knowledge about recipients and donor offspring was seen as ’damaging’ as it could create unwanted feelings of relatedness and responsibility towards them. All men acknowledged donor conceived persons’ potential interests in knowing about their genetic heritage in order to understand appearance and personal traits, but also emphasized the donors’ rights to anonymity. Potential breach of anonymity was generally considered ’highly problematic’ as it was expected to disturb their families and force a relationship on them. Conclusion This study reports on former donors who might not have volunteered for research due to lack of interest or protection of privacy. The majority of men valued anonymity and clearly demarcated a line between sperm donation and fatherhood, which was enforced by not knowing about the donor offspring or recipients

Chromatin compaction in terminally differentiated avian blood cells: the role of linker histone H5 and non-histone protein MENT

Chromatin has a tendency to shift from a relatively decondensed (active) to condensed (inactive) state during cell differentiation due to interactions of specific architectural and/or regulatory proteins with DNA. A promotion of chromatin folding in terminally differentiated avian blood cells requires the presence of either histone H5 in erythrocytes or non-histone protein, myeloid and erythroid nuclear termination stage-specific protein (MENT), in white blood cells (lymphocytes and granulocytes). These highly abundant proteins assist in folding of nucleosome arrays and self-association of chromatin fibers into compacted chromatin structures. Here, we briefly review structural aspects and molecular mode of action by which these unrelated proteins can spread condensed chromatin to form inactivated regions in the genome

Histone H1 Subtypes Differentially Modulate Chromatin Condensation without Preventing ATP-Dependent Remodeling by SWI/SNF or NURF

Although ubiquitously present in chromatin, the function of the linker histone subtypes is partly unknown and contradictory studies on their properties have been published. To explore whether the various H1 subtypes have a differential role in the organization and dynamics of chromatin we have incorporated all of the somatic human H1 subtypes into minichromosomes and compared their influence on nucleosome spacing, chromatin compaction and ATP-dependent remodeling. H1 subtypes exhibit different affinities for chromatin and different abilities to promote chromatin condensation, as studied with the Atomic Force Microscope. According to this criterion, H1 subtypes can be classified as weak condensers (H1.1 and H1.2), intermediate condensers (H1.3) and strong condensers (H1.0, H1.4, H1.5 and H1x). The variable C-terminal domain is required for nucleosome spacing by H1.4 and is likely responsible for the chromatin condensation properties of the various subtypes, as shown using chimeras between H1.4 and H1.2. In contrast to previous reports with isolated nucleosomes or linear nucleosomal arrays, linker histones at a ratio of one per nucleosome do not preclude remodeling of minichromosomes by yeast SWI/SNF or Drosophila NURF. We hypothesize that the linker histone subtypes are differential organizers of chromatin, rather than general repressors

Board-CEO friendship ties and firm value: Evidence from US firms

This study examines the impact of board-CEO friendship ties on firm value and explores potential channels through which changes in firm value may be conveyed, based on a sample of 1696 publicly listed firms in U.S. over the period of 2000–2014. The study reveals that board-CEO friendship ties have a negative and economically meaningful impact on firm value, as measured by Tobin's Q and Total Q. Regarding potential channels of firm value, we show that the negative influence of board-CEO friendship ties on firm value is reduced in firms with greater board advising requirements but intensified in firms with higher board monitoring needs. We also find social ties tend to destroy firm value whereas professional ties do not. Our results are robust to endogeneity concerns, and after controlling for board-CEO professional ties

A determining influence for CpG dinucleotides on nucleosome positioning in vitro

DNA sequence information that directs the translational positioning of nucleosomes can be attenuated by cytosine methylation when a short run of CpG dinucleotides is located close to the dyad axis of the nucleosome. Here, we show that point mutations introduced to re-pattern methylation at the (CpG)(3) element in the chicken β(A)-globin promoter sequence themselves strongly influenced nucleosome formation in reconstituted chromatin. The disruptive effect of cytosine methylation on nucleosome formation was found to be determined by the sequence context of CpG dinucleotides, not just their location in the positioning sequence. Additional mutations indicated that methylation can also promote the occupation of certain nucleosome positions. DNase I analysis demonstrated that these genetic and epigenetic modifications altered the structural characteristics of the (CpG)(3) element. Our findings support a proposal that the intrinsic structural properties of the DNA at the −1.5 site, as occupied by (CpG)(3) in the nucleosome studied, can be decisive for nucleosome formation and stability, and that changes in anisotropic DNA bending or flexibility at this site explain why nucleosome positioning can be exquisitely sensitive to genetic and epigenetic modification of the DNA sequence