A guide to photosynthetic gas exchange measurements: Fundamental principles, best practice and potential pitfalls.

Gas exchange measurements enable mechanistic insights into the processes that underpin carbon and water fluxes in plant leaves which in turn inform understanding of related processes at a range of scales from individual cells to entire ecosytems. Given the importance of photosynthesis for the global climate discussion it is important to (a) foster a basic understanding of the fundamental principles underpinning the experimental methods used by the broad community, and (b) ensure best practice and correct data interpretation within the research community. In this review, we outline the biochemical and biophysical parameters of photosynthesis that can be investigated with gas exchange measurements and we provide step-by-step guidance on how to reliably measure them. We advise on best practices for using gas exchange equipment and highlight potential pitfalls in experimental design and data interpretation. The Supporting Information contains exemplary data sets, experimental protocols and data-modelling routines. This review is a community effort to equip both the experimental researcher and the data modeller with a solid understanding of the theoretical basis of gas-exchange measurements, the rationale behind different experimental protocols and the approaches to data interpretation.

Reducing stomatal density by expression of a synthetic Epidermal Patterning Factor increases leaf intrinsic water use efficiency and reduces plant water use in a C4 crop.

Enhancing crop water use efficiency (WUE) is a key target trait for climatic resilience and expanding cultivation on marginal lands. Engineering lower stomatal density to reduce stomatal conductance (gs) has improved WUE in multiple C3 crop species. However, reducing gs in C3 species often reduces photosynthetic carbon gain. A different response is expected in C4 plants because they possess specialized anatomy and biochemistry which concentrates CO2 at the site of fixation. This modifies the photosynthesis (AN) relationship with intracellular CO2 concentration (ci) so that photosynthesis is CO2-saturated and reductions in gs are unlikely to limit AN. To test this hypothesis, genetic strategies were investigated to reduce stomatal density in the C4 crop sorghum. Constitutive expression of a synthetic epidermal patterning factor (EPF) transgenic allele in sorghum, led to reduced stomatal densities, reduced gs, reduced plant water use and avoidance of stress during a period of water deprivation. In addition, moderate reduction in stomatal density did not increase stomatal limitation to AN. However, these positive outcomes were associated with negative pleiotropic effects on reproductive development and photosynthetic capacity. Avoiding pleiotropy by targeting expression of the transgene to specific tissues could provide a pathway to improved agronomic outcomes.

Pre-morbid sleep disturbance and its association with stroke severity: results from the international INTERSTROKE study.

BACKGROUND AND PURPOSE: Whilst sleep disturbances are associated with stroke, their association with stroke severity is less certain. In the INTERSTROKE study, the association of pre-morbid sleep disturbance with stroke severity and functional outcome following stroke was evaluated. METHODS: INTERSTROKE is an international case-control study of first acute stroke. This analysis included cases who completed a standardized questionnaire concerning nine symptoms of sleep disturbance (sleep onset latency, duration, quality, nocturnal awakening, napping duration, whether a nap was planned, snoring, snorting and breathing cessation) in the month prior to stroke (n = 2361). Two indices were derived representing sleep disturbance (range 0-9) and obstructive sleep apnoea (range 0-3) symptoms. Logistic regression was used to estimate the magnitude of association between symptoms and stroke severity defined by the modified Rankin Score. RESULTS: The mean age of participants was 62.9 years, and 42% were female. On multivariable analysis, there was a graded association between increasing number of sleep disturbance symptoms and initially severe stroke (2-3, odds ratio [OR] 1.44, 95% confidence interval [CI] 1.07-1.94; 4-5, OR 1.66, 95% CI 1.23-2.25; >5, OR 2.58, 95% CI 1.83-3.66). Having >5 sleep disturbance symptoms was associated with significantly increased odds of functional deterioration at 1 month (OR 1.54, 95% CI 1.01-2.34). A higher obstructive sleep apnoea score was also associated with significantly increased odds of initially severe stroke (2-3, OR 1.48; 95% CI 1.20-1.83) but not functional deterioration at 1 month (OR 1.19, 95% CI 0.93-1.52). CONCLUSIONS: Sleep disturbance symptoms were common and associated with an increased odds of severe stroke and functional deterioration. Interventions to modify sleep disturbance may help prevent disabling stroke/improve functional outcomes and should be the subject of future research.

Estimating and displaying population attributable fractions using the R package: graphPAF.

Here we introduce graphPAF, a comprehensive R package designed for estimation, inference and display of population attributable fractions (PAF) and impact fractions. In addition to allowing inference for standard population attributable fractions and impact fractions, graphPAF facilitates display of attributable fractions over multiple risk factors using fan-plots and nomograms, calculations of attributable fractions for continuous exposures, inference for attributable fractions appropriate for specific risk factor → mediator → outcome pathways (pathway-specific attributable fractions) and Bayesian network-based calculations and inference for joint, sequential and average population attributable fractions in multi-risk factor scenarios. This article can be used as both a guide to the theory of attributable fraction estimation and a tutorial regarding how to use graphPAF in practical examples.

Bias assessment and correction for Levin's population attributable fraction in the presence of confounding.

In 1953, Morton Levin introduced a simple approach to estimating population attributable fractions (PAF) depending only on risk factor prevalence and relative risk. This formula and its extensions are still in widespread use today, particularly to estimate PAF in populations where individual data is unavailable. Unfortunately, Levin's approach is known to be asymptotically biased for the PAF when the risk factor-disease relationship is confounded even if relative risks that are correctly adjusted for confounding are used in the estimator. Here we describe a simple re-expression of Miettinen's estimand that depends on the causal relative risk, the unadjusted relative risk and the population risk factor prevalence. While this re-expression is not new, it has been underappreciated in the literature, and the associated estimator may be useful in estimating PAF in populations when individual data is unavailable provided estimated adjusted and unadjusted relative risks can be transported to the population of interest. Using the re-expressed estimand, we develop novel analytic formulae for the relative and absolute asymptotic bias in Levin's formula, solidifying earlier work by Darrow and Steenland that used simulations to investigate this bias. We extend all results to settings with non-binary valued risk factors and continuous exposures and discuss the utility of these results in estimating PAF in practice.

Effectiveness of HealthTracker for post-caesarean section surgical site infection surveillance: An intervention study.

This intervention study aimed to implement and evaluate the effectiveness of HealthTracker, a post-discharge surgical site infection surveillance system. Participants were 730 women birthing by caesarean section at a large hospital over a 6-month period. Data were downloaded from clinical data systems and HealthTracker. Receiver operating characteristics were used to assess HealthTracker. Over a 6-month period, 382 women completed HealthTracker, with 83 scoring ≥6, indicating signs and symptoms of surgical site infection. Of this 83, 58 sought advice from health professionals, 29 returned to hospital, and 45 received antibiotics. A total of 20 infections from a total population of 730 were confirmed, with 14 out of 382 respondents confirmed via HealthTracker. Receiver operating characteristics identified HealthTracker as an excellent indicator of surgical site infection. HealthTracker is a feasible mHealth option for monitoring post-discharge surgical site infection post-caesarean section. In addition, by providing alerts, advising women to monitor their symptoms and seek treatment if necessary, HealthTracker has the potential to enhance self-efficacy for surgical wound monitoring at home.

Endobronchial Infection and Bacterial Lymphadenitis by Gemella morbillorum Leading to Airway Perforation and a Bronchopleural Fistula.

Introduction: Necrotizing bronchial infection with severe infectious lymphadenitis is infrequently encountered and most commonly ascribed to Aspergillus, Histoplasma, and Mycobacterium species. We present a unique cause of severe airway destruction with lymphadenitis and bronchopleural fistula formation by the bacterium Gemella morbillorum. Case: A 24-year-old man presented with acute symptoms of vomiting, fever, and shoulder pain. A CT of the chest demonstrated a large subcarinal mass encasing the central bronchi. The workup for malignant, fungal, and granulomatous etiologies was unrevealing, while blood cultures identified G. morbillorum. Fiberoptic bronchoscopy revealed a perforation of the right middle lobar bronchus and the formation of a bronchopleural fistula, resulting in a large hydropneumothorax with empyema. Despite antibiotic therapy, surgical intervention to repair the fistula, and ventilatory support, the progression of the bronchopleural fistula led to fatal respiratory failure. Conclusion: In cases of severe mediastinal adenopathy in a young patient, bacterial lymphadenitis should be considered in the differential diagnosis with lymphoma, germ cell tumor, granulomatosis with polyangiitis, sarcoidosis, histoplasmosis, and inflammatory myofibroblastic tumor.

Understanding the Risk Factors and Pathogenesis of Disseminated Nocardiosis in Immunocompromised Patients.

Nocardia is a genus of aerobic, Gram-positive, partially acid-fast, filamentous bacilli notoriously known for causing multisystemic infections in immunocompromised individuals. Notably, this genus of bacteria commonly infects the pleural and central nervous system, leading to pneumonia and brain abscesses, respectively. Our patient is a 71-year-old female who initially presented to the emergency department complaining of shortness of breath and altered mental status. Imaging revealed multiple enhancing brain lesions, a pleural effusion, and a paraspinal abscess, which upon aspiration and culture demonstrated Nocardia farcinica/kroppenstedtii. The patient underwent antibiotic treatment, including intravenous (IV) imipenem and trimethoprim/sulfamethoxazole (TMP-SMX), before being transitioned to oral TMP-SMX and amoxicillin/clavulanate. This case demonstrates the importance of diagnosing nocardiosis acutely and treating it appropriately.

Sutton-Kadir Syndrome can be treated safely with endovascular embolisation alone.

INTRODUCTION: Sutton-Kadir Syndrome (SKS) describes true inferior pancreaticoduodenal artery (IPDA) aneurysms in the setting of coeliac artery (CA) stenosis or occlusion. Although rare, SKS aneurysms can rupture and cause morbidity. Due to its rarity and lack of controlled treatment data, correct treatment for the CA lesion is currently unknown. Our aim was to assess if endovascular embolisation alone was safe and effective in treatment of SKS aneurysms, in emergent and elective settings. Secondary objectives were to describe presentation and imaging findings. METHODS: A retrospective cohort study of patients treated at Sir Charles Gairdner Hospital between January 2014 and December 2021 was done. Data on presentation, diagnostics, aneurysm characteristics, CA lesion aetiology, treatment and outcomes were extracted from chart review. RESULTS: Twenty-four aneurysms in 14 patients were identified. Rupture was seen in 7/15 patients. Most aneurysms (22/24) were in the IPDA or one of its anterior or posterior branches. Median arcuate ligament (MAL) compression was identified in all. There was no difference in median (IQR) maximal transverse diameter between ruptured and non-ruptured aneurysms (6 mm (9), 12 mm (6), P = 0.18). Of ruptures, 6/7 had successful endovascular embolisation and 1/7 open surgical ligation. Of non-ruptures, 6/7 had successful endovascular embolisation, 1/7 open MAL division then endovascular CA stenting and aneurysm embolisation. No recurrences or new aneurysms were detected with computed tomography or magnetic resonance angiography over a median (IQR) follow-up period of 30 (10) months in 12 patients. CONCLUSION: Endovascular embolisation of SKS aneurysms without treatment of MAL compression is safe and effective in both the emergent and elective settings.

Relationships Between Applied Mindfulness Practice, Chronic Pain, and Pain-Related Functioning in Veterans.

Mindfulness-based interventions (MBIs) have been shown to improve chronic pain and associated conditions like depression, anxiety, and sleep disorders. However, there is limited research on how veterans with chronic pain apply mindfulness skills to manage pain in daily life. This cross-sectional study examined the association between applied mindfulness practice, pain, and several pain-related conditions among 1,737 veterans with chronic pain prior to enrollment in a trial of 2 MBIs. Applied mindfulness practice was assessed using the Applied Mindfulness Process Scale (AMPS). The outcomes included pain interference, pain intensity, pain catastrophizing, fatigue, sleep disturbance, anxiety, depression, post-traumatic stress disorder, physical function, and social participation. Higher overall AMPS scores, as well as the positive and negative emotional regulation subscales of the AMPS, were associated with less pain interference and catastrophizing, as well as better outcomes for all pain-related conditions. The positive emotional regulation subscale had the strongest associations with outcomes. There was no significant association between the AMPS and pain intensity. The results suggest applied mindfulness practice, especially positive emotional regulation, may improve pain and functioning. In addition, the AMPS shows promise as a process measure of mindfulness skills applied in daily life. Additional research is needed to examine different aspects of mindfulness in the context of MBIs. PERSPECTIVE: This article describes the relationship between applied mindfulness practice and pain-related outcomes, prior to a MBI, using a novel measure of mindfulness practice. These findings underscore the importance of measuring applied mindfulness practice prior to and during clinical interventions to treat chronic pain.

Email recruitment for chronic pain clinical trials: results from the LAMP trial.

BACKGROUND: Recruitment for clinical trials and large-scale studies is challenging, especially for patients with complex conditions like chronic pain. Email recruitment has the potential to increase efficiency, to reduce costs, and to improve access for underrepresented patient populations. The objective of this study was to examine the effectiveness, efficiency, and equitability of email versus postal mail recruitment for the Learning to Apply Mindfulness to Pain (LAMP) study, a three-site clinical trial of mindfulness-based interventions for chronic pain. METHODS: Patients with chronic pain diagnoses were recruited from three United States Department of Veterans Affairs (VA) facilities using the VA electronic health record (EHR). Recruitment materials were sent using either postal mail (n = 7986) or email (n = 19,333). Patients in the email recruitment group were also mailed introductory postcards before any emails. Mailing addresses and email addresses were obtained from the EHR. Effectiveness was measured by the response rate of patients who logged into the secure LAMP study website. Efficiency was measured by the number of days from when the recruitment materials were sent to when patients logged into the LAMP portal as well as the estimated costs of each recruitment approach. To assess equitability, we examined whether email recruitment was less effective for underrepresented populations, based on demographic information from the EHR. RESULTS: Effectiveness-unadjusted response rates were greater for email versus postal-mail recruitment (18.9% versus 6.3%), and adjusted response rates were over three times greater for email recruitment (RR = 3.5, 95% CI 3.1-3.8) based on a multivariable analysis controlling for age, gender, race, ethnicity, rurality, and site. Efficiency-email recruitment had a significantly lower mean response time (1 day versus 8 days) and a lower cost. Equity-email recruitment led to higher response rates for all subpopulations, including older, non-White, Hispanic, rural, and female Veterans. CONCLUSIONS: Email recruitment is an effective, efficient, and equitable way to recruit VA patients to large-scale, chronic pain clinical trials. TRIAL REGISTRATION: Clinical Trial Registration Number: NCT04526158. Patient enrollment began on December 4, 2020.

Exploring Gender Differences in Veterans in a Secondary Analysis of a Randomized Controlled Trial of Mindfulness for Chronic Pain.

Background: Although studies have documented higher rates of chronic pain among women Veterans compared to men Veterans, there remains a lack of comprehensive information about potential contributors to these disparities. Materials and Methods: This study examined gender differences in chronic pain and its contributors among 419 men and 392 women Veterans, enrolled in a mindfulness trial for chronic pain. We conducted descriptive analyses summarizing distributions of baseline measures, obtained by survey and through the electronic health record. Comparisons between genders were conducted using chi-square tests for categorical variables and t-tests for continuous measures. Results: Compared to men, women Veterans were more likely to have chronic overlapping pain conditions and had higher levels of pain interference and intensity. Women had higher prevalence of psychiatric and sleep disorder diagnoses, greater levels of depression, anxiety, post-traumatic stress disorder, fatigue, sleep disturbance, stress and pain catastrophizing, and lower levels of pain self-efficacy and participation in social roles and activities. However, women were less likely to smoke or have a substance abuse disorder and used more nonpharmacological pain treatment modalities. Conclusion: Among Veterans seeking treatment for chronic pain, women differed from men in their type of pain, had greater pain intensity and interference, and had greater prevalence and higher levels of many known biopsychosocial contributors to pain. Results point to the need for pain treatment that addresses the comprehensive needs of women Veterans.Clinical Trial Registration Number: NCT04526158. Patient enrollment began on December 4, 2020.

Gender differences in PTSD severity and pain outcomes: Baseline results from the LAMP trial.

BACKGROUND: Post-traumatic stress disorder (PTSD) and chronic pain are highly prevalent comorbid conditions. Veterans dually burdened by PTSD and chronic pain experience more severe outcomes compared to either disorder alone. Few studies have enrolled enough women Veterans to test gender differences in pain outcomes [catastrophizing, intensity, interference] by the severity of PTSD symptoms. AIM: Examine gender differences in the association between PTSD symptoms and pain outcomes among Veterans enrolled in a chronic pain clinical trial. METHODS: Participants were 421 men and 386 women Veterans with chronic pain who provided complete data on PTSD symptoms and pain outcomes. We used hierarchical linear regression models to examine gender differences in pain outcomes by PTSD symptoms. RESULTS: Adjusted multivariable models indicated that PTSD symptoms were associated with higher levels of pain catastrophizing (0.57, 95% CI [0.51, 0.63]), pain intensity (0.30, 95% CI [0.24, 0.37]), and pain interference (0.46, 95% CI [0.39, 0.52]). No evidence suggesting gender differences in this association were found in either the crude or adjusted models (all interaction p-values<0.05). CONCLUSION: These findings may reflect the underlying mutual maintenance of these conditions whereby the sensation of pain could trigger PTSD symptoms, particularly if the trauma and pain are associated with the same event. Clinical implications and opportunities testing relevant treatments that may benefit both chronic pain and PTSD are discussed.

Post-resolution macrophages shape long-term tissue immunity and integrity in a mouse model of pneumococcal pneumonia.

Resolving inflammation is thought to return the affected tissue back to homoeostasis but recent evidence supports a non-linear model of resolution involving a phase of prolonged immune activity. Here we show that within days following resolution of Streptococcus pneumoniae-triggered lung inflammation, there is an influx of antigen specific lymphocytes with a memory and tissue-resident phenotype as well as macrophages bearing alveolar or interstitial phenotype. The transcriptome of these macrophages shows enrichment of genes associated with prostaglandin biosynthesis and genes that drive T cell chemotaxis and differentiation. Therapeutic depletion of post-resolution macrophages, inhibition of prostaglandin E2 (PGE2) synthesis or treatment with an EP4 antagonist, MF498, reduce numbers of lung CD4+/CD44+/CD62L+ and CD4+/CD44+/CD62L-/CD27+ T cells as well as their expression of the α-integrin, CD103. The T cells fail to reappear and reactivate upon secondary challenge for up to six weeks following primary infection. Concomitantly, EP4 antagonism through MF498 causes accumulation of lung macrophages and marked tissue fibrosis. Our study thus shows that PGE2 signalling, predominantly via EP4, plays an important role during the second wave of immune activity following resolution of inflammation. This secondary immune activation drives local tissue-resident T cell development while limiting tissue injury.

Telehealth Mindfulness-Based Interventions for Chronic Pain: The LAMP Randomized Clinical Trial.

Importance: Although mindfulness-based interventions (MBIs) are evidence-based treatments for chronic pain and comorbid conditions, implementing them at scale poses many challenges, such as the need for dedicated space and trained instructors. Objective: To examine group and self-paced, scalable, telehealth MBIs, for veterans with chronic pain, compared to usual care. Design, Setting, and Participants: This was a randomized clinical trial of veterans with moderate to severe chronic pain, recruited from 3 Veterans Affairs facilities from November 2020 to May 2022. Follow-up was completed in August 2023. Interventions: Two 8-week telehealth MBIs (group and self-paced) were compared to usual care (control). The group MBI was done via videoconference with prerecorded mindfulness education and skill training videos by an experienced instructor, accompanied by facilitated discussions. The self-paced MBI was similar but completed asynchronously and supplemented by 3 individual facilitator calls. Main Outcomes and Measures: The primary outcome was pain-related function using the Brief Pain Inventory interference scale at 3 time points: 10 weeks, 6 months, and 1 year. Secondary outcomes included biopsychosocial outcomes: pain intensity, physical function, anxiety, fatigue, sleep disturbance, participation in social roles and activities, depression, patient ratings of improvement of pain, and posttraumatic stress disorder. Results: Among 811 veterans randomized (mean [SD] age, 54.6 [12.9] years; 387 [47.7%] women), 694 participants (85.6%) completed the trial. Averaged across all 3 time points, pain interference scores were significantly lower for both MBIs compared to usual care (group MBI vs control difference: -0.4 [95% CI, -0.7 to -0.2]; self-paced vs control difference: -0.7 [95% CI, -1.0 to -0.4]). Additionally, both MBI arms had significantly better scores on the following secondary outcomes: pain intensity, patient global impression of change, physical function, fatigue, sleep disturbance, social roles and activities, depression, and posttraumatic stress disorder. Both group and self-paced MBIs did not significantly differ from one another. The probability of 30% improvement from baseline compared to control was greater for group MBI at 10 weeks and 6 months, and for self-paced MBI, at all 3 time points. Conclusions and Relevance: In this randomized clinical trial, scalable telehealth MBIs improved pain-related function and biopsychosocial outcomes compared to usual care among veterans with chronic pain. Relatively low-resource telehealth-based MBIs could help accelerate and improve the implementation of nonpharmacological pain treatment in health care systems. Trial Registration: ClinicalTrials.gov Identifier: NCT04526158.

Tobacco use and risk of acute stroke in 32 countries in the INTERSTROKE study: a case-control study.

Background: Smoking is a major risk factor for the global burden of stroke. We have previously reported a global population attributable risk (PAR) of stroke of 12.4% associated with current smoking. In this study we aimed to explore the association of current tobacco use with different types of tobacco exposure and environmental tobacco smoke (ETS) exposure on the risk of stroke and stroke subtypes, and by regions and country income levels. Methods: The INTERSTROKE study is a case-control study of acute first stroke and was undertaken with 13,462 stroke cases and 13,488 controls recruited between January 11, 2007 and August 8, 2015 in 32 countries worldwide. Association of risk of tobacco use and ETS exposure were analysed with overall stroke, ischemic and intracerebral hemorrhage (ICH), and with TOAST etiological stroke subtypes (large vessel, small vessel, cardioembolism, and undetermined). Findings: Current smoking was associated with an increased risk of all stroke (odds ratio [OR] 1.64, 95% CI 1.46-1.84), and had a stronger association with ischemic stroke (OR 1.85, 95% CI 1.61-2.11) than ICH (OR 1.19 95% CI 1.00-1.41). The OR and PAR of stroke among current smokers varied significantly between regions and income levels with high income countries (HIC) having the highest odds (OR 3.02 95% CI 2.24-4.10) and PAR (18.6%, 15.1-22.8%). Among etiological subtypes of ischemic stroke, the strongest association of current smoking was seen for large vessel stroke (OR 2.16, 95% CI 1.63-2.87) and undetermined cause (OR 1.97, 95% CI 1.55-2.50). Both filtered (OR 1.73, 95% CI 1.50-1.99) and non-filtered (OR 2.59, 95% CI 1.79-3.77) cigarettes were associated with stroke risk. ETS exposure increased the risk of stroke in a dose-dependent manner, exposure for more than 10 h per week increased risk for all stroke (OR 1.95, 95% CI 1.69-2.27), ischemic stroke (OR 1.89, 95% CI 1.59-2.24) and ICH (OR 2.00, 95% CI 1.60-2.50). Interpretation: There are significant variations in the magnitude of risk and PAR of stroke according to the types of tobacco used, active and ETS exposure, and countries with different income levels. Specific strategies to discourage tobacco use by any form and to build a smoke free environment should be implemented to ease the global burden of stroke. Funding: The Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, Canadian Stroke Network, Swedish Research Council, Swedish Heart and Lung Foundation, The Health & Medical Care Committee of the Regional Executive Board, Region Västra Götaland, and through unrestricted grants from several pharmaceutical companies with major contributions from Astra Zeneca, Boehringer Ingelheim (Canada), Pfizer (Canada), MERCK, Sharp and Dohme, Swedish Heart and Lung Foundation, UK Chest, and UK Heart and Stroke.