Variability of the thrombin- and ADP-induced Ca2+ response among human platelets measured using fluo-3 and fluorescent videomicroscopy

AbstractThe intracellular free Ca2+ concentration ([Ca2+]cyt) of individual human platelets localized between siliconized glass cover slips was determined at rest and after stimulation with thrombin and ADP using the Ca2+ indicator fluo-3 (0.97 ± 0.30 mmol/1 cell volume) with fluorescence video microscopy. Resting [Ca2+]cyt in the presence of 2 mM external Ca2+ showed only small inter-platelet variability ([Ca2+]cyt = 86 ± 30 (S.D.) nM). Resting [Ca2+]cyt of individual fluo-3-loaded platelets measured as a function of time had a S.D. of 10 nM or 12% (S.D./mean). Individual platelets showed no affinity for the siliconized support and their [Ca2+]cyt showed no tendency to oscillate in either the resting or in the activated state. When 0.2 U/ml thrombin or 20 μM ADP were added, all platelets showed a characteristic Ca2+ transient whereby [Ca2+]cyt increased to peak values within 8–12 sec and then declined. The Ca2+ transients measured with fluo-3 were in approximate synchrony but peak [Ca2+]cyt values showed large inter-platelet variability. The ensemble average peak [Ca2+]cyt for thrombin and ADP were 672 ± 619 (S.D.) nM and 640 ± 642 (S.D.) nM, respectively. Thus inter-platelet variations (S.D./mean) were 92% or 100% as large as the average measured values. Mathematically-constructed averages of the single platelet experiments agreed reasonably well with platelet-averaged values obtained in parallel experiments with stirred platelet suspensions in a plastic cuvette, measured with a conventional spectrofluorometer. Peak [Ca2+]cyt values reflecting dense tubular Ca2+ release alone (external Ca2+ removed) also showed large interplatelet variation (171 ± 105 (S.D.) nM with thrombin and 183 ± 134 (S.D.) nM with ADP). Dense tubular Ca2+ release induced by cyclopiazonic acid (a dense tubular Ca2+-ATPase inhibitor) gave peak [Ca2+]cyt of 289 ± 170 nM. Thus the size of the dense tubular Ca2+ pool has an inter-platelet variation of 59% (S.D./mean). Variability of the dense tubular pool size accounts for some, but not all, of the large interplatelet variation in peak [Ca2+]cyt seen with thrombin and ADP activation

Impact of Multiple Factors on the Degree of Tinnitus Distress

Objective: The primary cause of subjective tinnitus is a dysfunction of the auditory system; however, the degree of distress tinnitus causes depends largely on the psychological status of the patient. Our goal was to attempt to associate the grade of tinnitus-related distress with the psychological distress, physical, or psychological discomfort patients experienced, as well as potentially relevant social parameters, through a simultaneous analysis of these factors. Methods: We determined the level of tinnitus-related distress in 531 tinnitus patients using the German version of the tinnitus questionnaire (TQ). In addition, we used the Perceived Stress Questionnaire (PSQ); General Depression Scale Allgemeine Depression Skala (ADS), Berlin Mood Questionnaire (BSF); somatic symptoms inventory (BI), and SF-8 health survey as well as general information collected through a medical history. Results: The TQ score significantly correlated with a score obtained using PSQ, ADS, BSF, BI, and SF-8 alongside psychosocial factors such as age, gender, and marital status. The level of hearing loss and the auditory properties of the specific tinnitus combined with perceived stress and the degree of depressive mood and somatic discomfort of a patient were identified as medium-strong predictors of chronic tinnitus. Social factors such as gender, age, or marital status also had an impact on the degree of tinnitus distress. The results that were obtained were implemented in a specific cortical distress network model. Conclusions: Using a large representative sample of patients with chronic tinnitus permitted a simultaneous statistical measurement of psychometric and audiological parameters in predicting tinnitus distress. We demonstrate that single factors can be distinguished in a manner that explains their causative association and influence on the induction of tinnitus-related distress

"We give them threatening advice…": expectations of adherence to antiretroviral therapy and their consequences among adolescents living with HIV in rural Malawi.

INTRODUCTION: Many adolescents living with HIV in sub-Saharan Africa struggle to achieve optimal adherence to antiretroviral therapy (ART), but few studies have investigated how their treatment-taking decisions are influenced by their social interactions with providers, caregivers and community leaders. This study aims to explore the narratives that define expectations of adherence to ART among adolescents living with HIV in a rural Malawian setting. METHODS: Overall, 45 in-depth interviews were conducted in 2016 with adolescents living with HIV, caregivers, health workers and community leaders, and four group sessions using participatory tools were undertaken with adolescents. Interviews and group sessions were audio-recorded, transcribed and translated into English. Data were coded inductively and analysed thematically. RESULTS: Adolescents were given strict behavioural codes around optimal treatment adherence, which were often enforced through encouragement, persuasian and threats. In HIV clinics, some staff supported adolescents with broader concerns relating to living with HIV, but other measures to address sub-optimal adherence in HIV clinics were perceived by patients as punitive, including pill-counts and increased frequency of clinic visits. Community leaders felt responsible for young peoples' health, sometimes attempting to influence their treatment-taking by threatening to withdraw services, or to publically "out" those deemed to be non-adherent. At home, discussions with adolescents about HIV were often limited to dose reminders, and some caretakers resorted to physical punishment to ensure adherence. While some adolescents complied with strictly-enforced adherence rules, others demonstrated resistance by hiding missed doses, secretly throwing away drugs, or openly refusing to take them. CONCLUSIONS: The potential of young people to adhere to their ART may be undermined by restrictive messages and punitive approaches to enforce and control their engagement with treatment at home, in the clinic and in the wider community. Interventions should focus on creating safe spaces for adolescents to speak frankly about the adherence challenges that they face and support for caregivers including home-based interventions

Tinnitus-related distress and pain perceptions in patients with chronic tinnitus – Do psychological factors constitute a link?

Objective: To investigate the co-occurrence of tinnitus-related distress and pain experiences alongside psychological factors that may underlie their association. Method: Patients with chronic tinnitus (N = 1238) completed a questionnaire battery examining tinnitus-related distress and affective and sensory pain perceptions. A series of simple, parallel- and serial multiple mediator models examined indirect effects of psychological comorbidities as well as -process variables including depressivity, perceived stress and coping attitudes. Moderator and moderated mediation analyses examined differential relational patterns in patients with decompensated vs. compensated tinnitus. Results: There were significant associations between tinnitus-related distress and pain perceptions. These were partially mediated by most specified variables. Psychological comorbidities appeared to influence tinnitus-pain associations through their impact on depressivity, perceived stress, and coping attitudes. Some specific differences in affective vs. sensory pain perception pathways emerged. Patients with decompensated tinnitus yielded significantly higher symptom burden across all measured indices. Tinnitus decompensation was associated with heightened associations between [1] tinnitus-related distress and pain perceptions, depressivity and negative coping attitudes; and [2] most psychological comorbidities and sensory, but not affective pain perception. Moderated mediation analyses revealed stronger indirect effects of depressivity and anxiety in mediating affective-, and anxiety in mediating sensory pain perception in patients with decompensated tinnitus. Conclusion: Psychological constructs mediate the co-occurrence of tinnitus- and pain-related symptoms across different levels of tinnitus-related distress. Psychological treatment approaches should conceptualize and address individualised interactions of common cognitive-emotional processes in addressing psychosomatic symptom clusters across syndromatic patients with varying distress levels

Linking model design and application for transdisciplinary approaches in social-ecological systems

This work was supported by the US National Science Foundation through the Mountain Sentinels Research Coordination Network (NSF #1414106), the Swiss National Science Foundation through MtnPaths – Pathways for global change adaptation of mountain socio-ecological systems (#20521L_169916), and the Center for Collaborative Conservation at Colorado State University.As global environmental change continues to accelerate and intensify, science and society are turning to trans- disciplinary approaches to facilitate transitions to sustainability. Modeling is increasingly used as a technological tool to improve our understanding of social-ecological systems (SES), encourage collaboration and learning, and facilitate decision-making. This study improves our understanding of how SES models are designed and applied to address the rising challenges of global environmental change, using mountains as a representative system. We analyzed 74 peer-reviewed papers describing dynamic models of mountain SES, evaluating them according to characteristics such as the model purpose, data and model type, level of stakeholder involvement, and spatial extent/resolution. Slightly more than half the models in our analysis were participatory, yet only 21.6% of papers demonstrated any direct outreach to decision makers. We found that SES models tend to under-represent social datasets, with ethnographic data rarely incorporated. Modeling efforts in conditions of higher stakeholder diversity tend to have higher rates of decision support compared to situations where stakeholder diversity is absent or not addressed. We discuss our results through the lens of appropriate technology, drawing on the concepts of boundary objects and scalar devices from Science and Technology Studies. We propose four guiding principles to facilitate the development of SES models as appropriate technology for transdisciplinary applications: (1) increase diversity of stakeholders in SES model design and application for improved collaboration; (2) balance power dynamics among stakeholders by incorporating diverse knowledge and data types; (3) promote flexibility in model design; and (4) bridge gaps in decision support, learning, and communication. Creating SES models that are appropriate tech- nology for transdisciplinary applications will require advanced planning, increased funding for and attention to the role of diverse data and knowledge, and stronger partnerships across disciplinary divides. Highly contextualized participatory modeling that embraces diversity in both data and actors appears poised to make strong contributions to the world’s most pressing environmental challenges.PostprintPeer reviewe

Using mobile devices and apps to support reflective learning about older people with dementia

There has been little research to develop computing technologies to support the care of people with dementia, in spite of the growing challenges that the condition poses for society. To design such technologies, an existing model of computer-support reflective learning was instantiated with findings from a pre-design study in one residential home. The result was a mobile device running an adapted enterprise social media app to support person-centred care. Evaluations of the device and app in two residential homes revealed that use of the app both motivated and increased different styles of care note recording, but little reflective learning was identified or reported. The results suggest the need for more comprehensive and flexible computer-based support for reflective learning about residents in their care – and new designs of this more comprehensive support are also introduced

Aging impairs the osteocytic regulation of collagen integrity and bone quality

Poor bone quality is a major factor in skeletal fragility in elderly individuals. The molecular mechanisms that establish and maintain bone quality, independent of bone mass, are unknown but are thought to be primarily determined by osteocytes. We hypothesize that the age-related decline in bone quality results from the suppression of osteocyte perilacunar/canalicular remodeling (PLR), which maintains bone material properties. We examined bones from young and aged mice with osteocyte-intrinsic repression of TGFβ signaling (TβRI

'I saw it as a second chance': A qualitative exploration of experiences of treatment failure and regimen change among people living with HIV on second- and third-line antiretroviral therapy in Kenya, Malawi and Mozambique.

Increasing numbers of people living with HIV (PLHIV) in sub-Saharan Africa are experiencing failure of first-line antiretroviral therapy and transitioning onto second-line regimens. However, there is a dearth of research on their treatment experiences. We conducted in-depth interviews with 43 PLHIV on second- or third-line antiretroviral therapy and 15 HIV health workers in Kenya, Malawi and Mozambique to explore patients' and health workers' perspectives on these transitions. Interviews were audio-recorded, transcribed and translated into English. Data were coded inductively and analysed thematically. In all settings, experiences of treatment failure and associated episodes of ill-health disrupted daily social and economic activities, and recalled earlier fears of dying from HIV. Transitioning onto more effective regimens often represented a second (or third) chance to (re-)engage with HIV care, with patients prioritising their health over other aspects of their lives. However, many patients struggled to maintain these transformations, particularly when faced with persistent social challenges to pill-taking, alongside the burden of more complex regimens and an inability to mobilise sufficient resources to accommodate change. Efforts to identify treatment failure and support regimen change must account for these patients' unique illness and treatment histories, and interventions should incorporate tailored counselling and social and economic support