Quantifying the influence of Bessel beams on image quality in optical coherence tomography

Light scattered by turbid tissue is known to degrade optical coherence tomography (OCT) image contrast progressively with depth. Bessel beams have been proposed as an alternative to Gaussian beams to image deeper into turbid tissue. However, studies of turbid tissue comparing the image quality for different beam types are lacking. We present such a study, using numerically simulated beams and experimental OCT images formed by Bessel or Gaussian beams illuminating phantoms with optical properties spanning a range typical of soft tissue. We demonstrate that, for a given scattering parameter, the higher the scattering anisotropy the lower the OCT contrast, regardless of the beam type. When focusing both beams at the same depth in the sample, we show that, at focus and for equal input power and resolution, imaging with the Gaussian beam suffers less reduction of contrast. This suggests that, whilst Bessel beams offer extended depth of field in a single depth scan, for low numerical aperture (NA  0.95), superior contrast (by up to ~40%) may be obtained over an extended depth range by a Gaussian beam combined with dynamic focusing

Optical coherence tomography-based contact indentation for diaphragm mechanics in a mouse model of transforming growth factor alpha induced lung disease

This study tested the utility of optical coherence tomography (OCT)-based indentation to assess mechanical properties of respiratory tissues in disease. Using OCT-based indentation, the elastic modulus of mouse diaphragm was measured from changes in diaphragm thickness in response to an applied force provided by an indenter. We used a transgenic mouse model of chronic lung disease induced by the overexpression of transforming growth factor-alpha (TGF-a), established by the presence of pleural and peribronchial fibrosis and impaired lung mechanics determined by the forced oscillation technique and plethysmography. Diaphragm elastic modulus assessed by OCT-based indentation was reduced by TGF-a at both left and right lateral locations (p < 0.05). Diaphragm elastic modulus at left and right lateral locations were correlated within mice (r = 0.67, p < 0.01) suggesting that measurements were representative of tissue beyond the indenter field. Co-localised images of diaphragm after TGF-a overexpression revealed a layered fibrotic appearance. Maximum diaphragm force in conventional organ bath studies was also reduced by TGF-a overexpression (p < 0.01). Results show that OCT-based indentation provided clear delineation of diseased diaphragm, and together with organ bath assessment, provides new evidence suggesting that TGF-a overexpression produces impairment in diaphragm function and, therefore, an increase in the work of breathing in chronic lung disease

P2X receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

P2X receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on P2X Receptors [46, 134]) have a trimeric topology [118, 132, 177] with two putative TM domains, gating primarily Na+, K+ and Ca2+, exceptionally Cl-. The Nomenclature Subcommittee has recommended that for P2X receptors, structural criteria should be the initial criteria for nomenclature where possible. X-ray crystallography indicates that functional P2X receptors are trimeric and three agonist molecules are required to bind to a single receptor in order to activate it [132, 88, 96, 161]. Native receptors may occur as either homotrimers (e.g. P2X1 in smooth muscle) or heterotrimers (e.g. P2X2:P2X3 in the nodose ganglion [251], P2X1:P2X5 in mouse cortical astrocytes [146], and P2X2:P2X5 in mouse dorsal root ganglion, spinal cord and mid pons [50, 207]. P2X2, P2X4 and P2X7 receptors have been shown to form functional homopolymers which, in turn, activate pores permeable to low molecular weight solutes [229]. The hemi-channel pannexin-1 has been implicated in the pore formation induced by P2X7 [188], but not P2X2 [38], receptor activation

Evaluation of training on palliative care for staff working within a homeless hostel

BACKGROUND: In the UK, many people experiencing homelessness whose health is deteriorating remain in homeless hostels due to few suitable alternative places of care. Hostel staff struggle to support residents with deteriorating health and palliative care services are rarely involved. There is recognition of the need for multiagency working to support this group. OBJECTIVES: To pilot and evaluate the impact of a two-day training course for hostel staff around supporting clients with palliative care needs, and increasing multiagency working. DESIGN: Mixed methods evaluation using pre-and-post training data collection. SETTINGS AND PARTICIPANTS: Frontline staff from two London homeless hostels. METHODS: Staff from two hostels attended a two day training course. Self-perceived confidence in supporting residents with deteriorating health, knowledge of palliative care, openness to discussing deteriorating health and work related stress were assessed at baseline and immediately after training using a novel questionnaire. Qualitative data was collected via focus groups immediately after and three months post-training. RESULTS: Twenty four participants attended at least one day of training, 21 (87%) completed the course. Training was reported to be useful and relevant. Modest improvements in self-perceived work related stress, knowledge, confidence and openness were observed following training. At three months, qualitative data indicated the beginnings of a shift in how palliative care was conceptualised and an increase in knowledge and confidence around supporting residents. Anxiety regarding the role of the hostel in palliative care, the recovery focused ethos of homelessness services and fragmented systems and services presented challenges to establishing changes. CONCLUSIONS: Training can be useful for improving knowledge, confidence, openness and work related stress. Recommendations for implementing changes in how people experiencing homelessness are supported include embedding training into routine practice, promoting multidisciplinary working, incorporating flexibility within the recovery focused approach of services and recognising the need for emotional support for staff

End-of-life care for homeless people: A qualitative analysis exploring the challenges to access and provision of palliative care

BACKGROUND: Being homeless or vulnerably housed is associated with death at a young age, frequently related to medical problems complicated by drug or alcohol dependence. Homeless people experience high symptom burden at the end of life, yet palliative care service use is limited. AIM: To explore the views and experiences of current and formerly homeless people, frontline homelessness staff (from hostels, day centres and outreach teams) and health- and social-care providers, regarding challenges to supporting homeless people with advanced ill health, and to make suggestions for improving care. DESIGN: Thematic analysis of data collected using focus groups and interviews. PARTICIPANTS: Single homeless people ( n = 28), formerly homeless people ( n = 10), health- and social-care providers ( n = 48), hostel staff ( n = 30) and outreach staff ( n = 10). RESULTS: This research documents growing concern that many homeless people are dying in unsupported, unacceptable situations. It highlights the complexities of identifying who is palliative and lack of appropriate places of care for people who are homeless with high support needs, particularly in combination with substance misuse issues. CONCLUSION: Due to the lack of alternatives, homeless people with advanced ill health often remain in hostels. Conflict between the recovery-focused nature of many services and the realities of health and illness for often young homeless people result in a lack of person-centred care. Greater multidisciplinary working, extended in-reach into hostels from health and social services and training for all professional groups along with more access to appropriate supported accommodation are required to improve care for homeless people with advanced ill health

Challenges to discussing palliative care with people experiencing homelessness: a qualitative study

OBJECTIVES: To explore the views and experiences of people who are homeless and those supporting them regarding conversations and approaches to palliative care SETTING: Data were collected between October 2015 and October 2016 in homeless hostels and day centres and with staff from primary and secondary healthcare providers and social care services from three London boroughs. PARTICIPANTS: People experiencing homelessness (n=28), formerly homeless people (n=10), health and social care providers (n=48), hostel staff (n=30) and outreach staff (n=10). METHODS: In this qualitative descriptive study, participants were recruited to interviews and focus groups across three London boroughs. Views and experiences of end-of-life care were explored with people with personal experience of homelessness, health and social care professionals and hostel and outreach staff. Saturation was reached when no new themes emerged from discussions. RESULTS: 28 focus groups and 10 individual interviews were conducted. Participants highlighted that conversations exploring future care preferences and palliative care with people experiencing homelessness are rare. Themes identified as challenges to such conversations included attitudes to death; the recovery focused nature of services for people experiencing homelessness; uncertainty regarding prognosis and place of care; and fear of negative impact. CONCLUSIONS: This research highlights the need for a different approach to supporting people who are homeless and are experiencing advanced ill health, one that incorporates uncertainty and promotes well-being, dignity and choice. We propose parallel planning and mapping as a way of working with uncertainty. We acknowledge that these approaches will not always be straightforward, nor will they be suitable for everyone, yet moving the focus of conversations about the future away from death and dying, towards the present and the future may facilitate conversations and enable the wishes of people who are homeless to be known and explored

Volumetric quantitative optical coherence elastography with an iterative inversion method

It is widely accepted that accurate mechanical properties of three-dimensional soft tissues and cellular samples are not available on the microscale. Current methods based on optical coherence elastography can measure displacements at the necessary resolution, and over the volumes required for this task. However, in converting this data to maps of elastic properties, they often impose assumptions regarding homogeneity in stress or elastic properties that are violated in most realistic scenarios. Here, we introduce novel, rigorous, and computationally efficient inverse problem techniques that do not make these assumptions, to realize quantitative volumetric elasticity imaging on the microscale. Specifically, we iteratively solve the threedimensional elasticity inverse problem using displacement maps obtained from compression optical coherence elastography. This is made computationally feasible with adaptive mesh refinement and domain decomposition methods. By employing a transparent, compliant surface layer with known shear modulus as a reference for the measurement, absolute shear modulus values are produced within a millimeter-scale sample volume. We demonstrate the method on phantoms, on an ex vivo breast cancer sample, and in vivo on human skin. Quantitative elastography on this length scale will find wide application in cell biology, tissue engineering and medicine

The modern pollen-vegetation relationship of a tropical forest-savannah mosaic landscape, Ghana, West Africa

Transitions between forest and savannah vegetation types in fossil pollen records are often poorly understood due to over-production by taxa such as Poaceae and a lack of modern pollen-vegetation studies. Here, modern pollen assemblages from within a forest-savannah transition in West Africa are presented and compared, their characteristic taxa discussed, and implications for the fossil record considered. Fifteen artificial pollen traps were deployed for 1 year, to collect pollen rain from three vegetation plots within the forest-savannah transition in Ghana. High percentages of Poaceae and Melastomataceae/Combretaceae were recorded in all three plots. Erythrophleum suaveolens characterised the forest plot, Manilkara obovata the transition plot and Terminalia the savannah plot. The results indicate that Poaceae pollen influx rates provide the best representation of the forest-savannah gradient, and that a Poaceae abundance of >40% should be considered as indicative of savannah-type vegetation in the fossil record

Recognition and Stigma of Prescription Drug Abuse Disorder: Personal and Community Determinants

Background Prescription drug abuse (PDA) disorders continue to contribute to the current American opioid crisis. Within this context, our study seeks to improve understanding about stigma associated with, and symptom recognition of, prescription drug abuse. Aims Model the stigma and symptom recognition of PDA in the general population. Methods A randomized, nation-wide, online, vignette-focused survey of the general public (N = 631) was implemented with an oversample for rural counties. Logit estimation was used for analysis, with regional and county-level sociodemographic variables as controls. Results Individual respondents that self-identify as having or having had “a prescription drug abuse issue” were less likely to correctly identify the condition and were 4 times more likely to exhibit stigma. Male respondents were approximately half as likely to correctly identify PDA as female respondents while older respondents (55+) were more likely to correctly identify PDA, relative to those aged 35–54. Being both male and younger was associated with slightly more stigma, in that they were less likely to disagree with the stigma statement. Conclusions In light of the continued risks that individuals with PDA behaviors face in potentially transitioning to illicit opioid use, the findings of this survey suggested a continued need for public education and outreach. Of particular note is the perspective of those who have self-identified with the condition, as this population faces the largest risks of adverse health outcomes from illicit drug use within the survey respondents

Pathological Investigation of Congenital Bicuspid Aortic Valve Stenosis, Compared with Atherosclerotic Tricuspid Aortic Valve Stenosis and Congenital Bicuspid Aortic Valve Regurgitation

Congenital bicuspid aortic valve (CBAV) is the main cause of aortic stenosis (AS) in young adults. However, the histopathological features of AS in patients with CBAV have not been fully investigated.We examined specimens of aortic valve leaflets obtained from patients who had undergone aortic valve re/placement at our institution for severe AS with CBAV (n = 24, CBAV-AS group), severe AS with tricuspid aortic valve (n = 24, TAV-AS group), and severe aortic regurgitation (AR) with CBAV (n = 24, CBAV-AR group). We compared the histopathological features among the three groups. Pathological features were classified using semi-quantitative methods (graded on a scale 0 to 3) by experienced pathologists without knowledge of the patients' backgrounds. The severity of inflammation, neovascularization, and calcium and cholesterol deposition did not differ between the CBAV-AS and TAV-AS groups, and these four parameters were less marked in the CBAV-AR group than in the CBAV-AS (all p<0.01). Meanwhile, the grade of valvular fibrosis was greater in the CBAV-AS group, compared with the TAV-AS and CBAV-AR groups (both p<0.01). In AS patients, thickness of fibrotic lesions was greater on the aortic side than on the ventricular side (both p<0.01). Meanwhile, thickness of fibrotic lesions was comparable between the aortic and ventricular sides in CBAV-AR patients (p = 0.35).Valvular fibrosis, especially on the aortic side, was greater in patients with CBAV-AS than in those without, suggesting a difference in the pathogenesis of AS between CBAV and TAV