Finding kindness: A randomized controlled trial of an online self-compassion intervention for weight management (SC4WM).

INTRODUCTION: Weight loss is hard to achieve and even harder to maintain. Engaging in effortful behavioural change to manage body weight can sometimes result in feelings of guilt and shame. Self-compassion, the tendency to find kindness for oneself in times of struggle, may facilitate coping with the unique challenges of weight management. This study assessed whether a remotely delivered self-compassion intervention improved weight management outcomes when delivered as a supplement to an existing digital behavioural weight management programme, Weight Watchers (WW). METHOD: Using a mixed-method study design, 249 adults seeking to manage weight were randomized to either the WW programme or WW supplemented with the self-compassion for weight management intervention (SC4WM). Participants completed measures of self-compassion, eating behaviour, physical activity, body weight and emotional well-being along with potential moderators, including weight self-stigma, eating restraint, psychological coping and perceived stress at baseline, post-intervention (4 weeks) and follow-up (12 weeks). RESULTS: There was no evidence that the SC4WM intervention had a significantly different effect than WW alone. Other than body weight, all outcomes improved over time in both groups. Self-compassion was slightly higher overall in the SC4WM group (p = .05), with this group reporting higher self-kindness at 4 weeks (p = .014) and lower self-judgement at 12 weeks (p = .023) compared to the control group. CONCLUSIONS: Although the SC4WM intervention group did show a small increase in self-kindness and reduction in self-judgement, weight management outcomes were not improved over and above the existing WW programme. Recommendations for adapting the SC4WM intervention to improve efficacy to augment weight management outcomes are provided.

At home adaptive dual target deep brain stimulation in Parkinson's disease with proportional control.

Continuous deep brain stimulation (cDBS) of the subthalamic nucleus (STN) or globus pallidus is an effective treatment for the motor symptoms of Parkinson's disease. The relative benefit of one region over the other is of great interest but cannot usually be compared in the same patient. Simultaneous DBS of both regions may synergistically increase the therapeutic benefit. Continuous DBS is limited by a lack of responsiveness to dynamic, fluctuating symptoms intrinsic to the disease. Adaptive DBS (aDBS) adjusts stimulation in response to biomarkers to improve efficacy, side effects, and efficiency. We combined bilateral DBS of both STN and globus pallidus (dual target DBS) in a prospective within-participant, clinical trial in six patients with Parkinson's disease (n = 6, 55-65 years, n = 2 females). Dual target cDBS was tested for Parkinson's disease symptom control annually over 2 years, measured by motor rating scales, on time without dyskinesia, and medication reduction. Random amplitude experiments probed system dynamics to estimate parameters for aDBS. We then implemented proportional-plus-integral aDBS using a novel distributed (off-implant) architecture. In the home setting, we collected tremor and dyskinesia scores as well as individualized ß and DBS amplitudes. Dual target cDBS reduced motor symptoms as measured by Unified Parkinson's Disease Rating Scale (UPDRS) to a greater degree than either region alone (P < 0.05, linear mixed model) in the cohort. The amplitude of ß-oscillations in the STN correlated to the speed of hand grasp movements for five of six participants (P < 0.05, Pearson correlation). Random amplitude experiments provided insight into temporal windowing to avoid stimulation artefacts and demonstrated a correlation between STN ß amplitude and DBS amplitude. Proportional plus integral control of aDBS reduced average power, while preserving UPDRS III scores in the clinic (P = 0.28, Wilcoxon signed rank), and tremor and dyskinesia scores during blinded testing at home (n = 3, P > 0.05, Wilcoxon ranked sum). In the home setting, DBS power reductions were slight but significant. Dual target cDBS may offer an improvement in treatment of motor symptoms of Parkinson's disease over DBS of either the STN or globus pallidus alone. When combined with proportional plus integral aDBS, stimulation power may be reduced, while preserving the increased benefit of dual target DBS.

Temporally non-regular patterns of deep brain stimulation (DBS) enhance assessment of evoked potentials while maintaining motor symptom management in Parkinson's disease (PD).

BACKGROUND: Traditional deep brain stimulation (DBS) at fixed regular frequencies (>100 Hz) is effective in treating motor symptoms of Parkinson's disease (PD). Temporally non-regular patterns of DBS are a new parameter space that may help increase efficacy and efficiency. OBJECTIVE: To compare the effects of temporally non-regular patterns of DBS to traditional regularly-spaced pulses. METHODS: We simultaneously recorded local field potentials (LFP) and monitored motor symptoms (tremor and bradykinesia) in persons with PD during DBS in subthalamic nucleus (STN). We quantified both oscillatory activity and DBS local evoked potentials (DLEPs) from the LFP. RESULTS: Temporally non-regular patterns were as effective as traditional pulse patterns in modulating motor symptoms, oscillatory activity, and DLEPs. Moreover, one of our novel patterns enabled recording of longer duration DLEPs during clinically effective stimulation. CONCLUSIONS: Stimulation gaps of 50 ms can be used to increase efficiency and to enable regular assessment of long-duration DLEPs while maintaining effective symptom management. This may be a promising paradigm for closed-loop DBS with biomarker assessment during the gaps.

Homologous recombination suppresses transgenerational DNA end resection and chromosomal instability in fission yeast.

Chromosomal instability (CIN) drives cell-to-cell heterogeneity, and the development of genetic diseases, including cancer. Impaired homologous recombination (HR) has been implicated as a major driver of CIN, however, the underlying mechanism remains unclear. Using a fission yeast model system, we establish a common role for HR genes in suppressing DNA double-strand break (DSB)-induced CIN. Further, we show that an unrepaired single-ended DSB arising from failed HR repair or telomere loss is a potent driver of widespread CIN. Inherited chromosomes carrying a single-ended DSB are subject to cycles of DNA replication and extensive end-processing across successive cell divisions. These cycles are enabled by Cullin 3-mediated Chk1 loss and checkpoint adaptation. Subsequent propagation of unstable chromosomes carrying a single-ended DSB continues until transgenerational end-resection leads to fold-back inversion of single-stranded centromeric repeats and to stable chromosomal rearrangements, typically isochromosomes, or to chromosomal loss. These findings reveal a mechanism by which HR genes suppress CIN and how DNA breaks that persist through mitotic divisions propagate cell-to-cell heterogeneity in the resultant progeny.

Offline Learning of Closed-Loop Deep Brain Stimulation Controllers for Parkinson Disease Treatment.

Deep brain stimulation (DBS) has shown great promise toward treating motor symptoms caused by Parkinson's disease (PD), by delivering electrical pulses to the Basal Ganglia (BG) region of the brain. However, DBS devices approved by the U.S. Food and Drug Administration (FDA) can only deliver continuous DBS (cDBS) stimuli at a fixed amplitude; this energy inefficient operation reduces battery lifetime of the device, cannot adapt treatment dynamically for activity, and may cause significant side-effects (e.g., gait impairment). In this work, we introduce an offline reinforcement learning (RL) framework, allowing the use of past clinical data to train an RL policy to adjust the stimulation amplitude in real time, with the goal of reducing energy use while maintaining the same level of treatment (i.e., control) efficacy as cDBS. Moreover, clinical protocols require the safety and performance of such RL controllers to be demonstrated ahead of deployments in patients. Thus, we also introduce an offline policy evaluation (OPE) method to estimate the performance of RL policies using historical data, before deploying them on patients. We evaluated our framework on four PD patients equipped with the RC+S DBS system, employing the RL controllers during monthly clinical visits, with the overall control efficacy evaluated by severity of symptoms (i.e., bradykinesia and tremor), changes in PD biomakers (i.e., local field potentials), and patient ratings. The results from clinical experiments show that our RL-based controller maintains the same level of control efficacy as cDBS, but with significantly reduced stimulation energy. Further, the OPE method is shown effective in accurately estimating and ranking the expected returns of RL controllers.

Self-compassion, Stress, and Eating Behaviour: Exploring the Effects of Self-compassion on Dietary Choice and Food Craving After Laboratory-Induced Stress.

BACKGROUND: Stress has been linked to high-fat and high-sugar food consumption. Self-compassion is associated with better emotional and physiological responses to stress. The current study explored whether trait self-compassion or induced state self-compassion could improve dietary choice and food craving after a stress induction. METHOD: Fifty-three university students completed an online survey assessing self-compassion, eating restraint, and general perceived stress before attending a laboratory visit. In the laboratory, participants were randomised to a neutral writing control or a self-compassion letter writing condition before a stress induction. Measures of heart rate, heart rate variability, state self-compassion, dietary choice, and state food cravings were taken. RESULTS: The brief self-compassion intervention did not sufficiently increase state self-compassion in the intervention group compared to the neutral writing condition. There was no effect of the written self-compassion intervention on heart rate, heart rate variability, dietary choice, or food craving. However, higher trait self-compassion was associated with healthier dietary choices (F(1, 49) = 5.35, p = .025, R2 = .098). CONCLUSION: Results suggest that higher trait self-compassion improved dietary choice after stress in a controlled environment in a university population. Further research is warranted to explore whether brief self-compassion interventions can improve state self-compassion and thereby influence dietary choices and food cravings after a stress induction.

Rethinking weight: Finding self-compassion for 'weight management'.

Conventional weight management approaches emphasize engaging in health behaviours, such as healthy eating and physical activity, to control body weight and promote favourable health outcomes (e.g., lower blood pressure). However, weight management is a multi-faceted, complex process influenced by numerous factors that limit the impact of behaviour change on weight. Self-compassion, treating oneself kindly in times of increased distress or difficulty, may offer a way for individuals to cope with the challenges of managing weight. The objectives of this perspective paper are threefold: (1) to conceptualize weight management, (2) to describe the problem that arises when focusing solely on weight loss, and (3) to explore the theoretical rationale for integrating self-compassion into weight management interventions. To support individual health and well-being, there is a need to reframe measures of success and provide innovative ways to cope with the challenges of managing body weight. Continued research is needed to investigate whether self-compassion can support health outcomes for those with weight management goals. This manuscript provides a proposed research agenda and implications for future practice.

Outcomes of intuitive eating interventions: a systematic review and meta-analysis.

Intuitive eating (IE) is an approach to health promotion that fosters a positive relationship with food and the body. The objective of this review was to aggregate and analyse the literature on IE interventions, thereby offering an early investigation of methodological approaches to intervention. This review was conducted in accordance with the preferred reporting items for systematic review and meta-analysis protocols (PRISMA) guidelines. Searching was conducted in four electronic databases. Studies were eligible for inclusion if they delivered an IE intervention and used the Intuitive Eating Scale (IES). Nine studies were included in this review. Six were eligible for meta-analysis, though only outcomes on the IES were examined; all other measures were examined individually. All interventions led to improvements on measures of IE, with a large pooled effect size (1.50 [1.15, 1.85]) and positive changes on a variety of other outcomes relating to health. This pattern preliminarily suggests that IE interventions change psychological processes as intended and can be useful in promoting health behaviour. The present review offers a synthesis of existing approaches to IE interventions and an evaluation of which specific variants appear to be more effective. This paper provides a basis upon which future interventions can be developed to improve approaches to psychoeducation.Clinical ImplicationsInterventions contributed to improvements in measures of IE lasting up to 6 months.Interventions contributed to positive changes on outcomes such as quality of life, body image, and body appreciation.Self-management through IE-based interventions may be feasible and effective.

Leaf water potential measurements using the pressure chamber: Synthetic testing of assumptions towards best practices for precision and accuracy.

Leaf water potential (ψleaf ), typically measured using the pressure chamber, is the most important metric of plant water status, providing high theoretical value and information content for multiple applications in quantifying critical physiological processes including drought responses. Pressure chamber measurements of ψleaf (ψleafPC ) are most typical, yet, the practical complexity of the technique and of the underlying theory has led to ambiguous understanding of the conditions to optimize measurements. Consequently, specific techniques and precautions diversified across the global research community, raising questions of reliability and repeatability. Here, we surveyed specific methods of ψleafPC from multiple laboratories, and synthesized experiments testing common assumptions and practices in ψleafPC for diverse species: (i) the need for equilibration of previously transpiring leaves; (ii) leaf storage before measurement; (iii) the equilibration of ψleaf for leaves on bagged branches of a range of dehydration; (iv) the equilibration of ψleaf across the lamina for bagged leaves, and the accuracy of measuring leaves with artificially 'elongated petioles'; (v) the need in ψleaf measurements for bagging leaves and high humidity within the chamber; (vi) the need to avoid liquid water on leaf surfaces; (vii) the use of 'pulse' pressurization versus gradual pressurization; and (viii) variation among experimenters in ψleafPC determination. Based on our findings we provide a best practice protocol to maximise accuracy, and provide recommendations for ongoing species-specific tests of important assumptions in future studies.

Initial Clinical Outcome With Bilateral, Dual-Target Deep Brain Stimulation Trial in Parkinson Disease Using Summit RC + S.

BACKGROUND: Deep brain stimulation (DBS) is an effective therapy in advanced Parkinson disease (PD). Although both subthalamic nucleus (STN) and globus pallidus (GP) DBS show equivalent efficacy in PD, combined stimulation may demonstrate synergism. OBJECTIVE: To evaluate the clinical benefit of stimulating a combination of STN and GP DBS leads and to demonstrate biomarker discovery for adaptive DBS therapy in an observational study. METHODS: We performed a pilot trial (n = 3) of implanting bilateral STN and GP DBS leads, connected to a bidirectional implantable pulse generator (Medtronic Summit RC + S; NCT03815656, IDE No. G180280). Initial 1-year outcome in 3 patients included Unified PD Rating Scale on and off medications, medication dosage, Hauser diary, and recorded beta frequency spectral power. RESULTS: Combined DBS improved PD symptom control, allowing >80% levodopa medication reduction. There was a greater decrease in off-medication motor Unified PD Rating Scale with multiple electrodes activated (mean difference from off stimulation off medications -18.2, range -25.5 to -12.5) than either STN (-12.8, range -20.5 to 0) or GP alone (-9, range -11.5 to -4.5). Combined DBS resulted in a greater reduction of beta oscillations in STN in 5/6 hemispheres than either site alone. Adverse events occurred in 2 patients, including a small cortical hemorrhage and seizure at 24 hours postoperatively, which resolved spontaneously, and extension wire scarring requiring revision at 2 months postoperatively. CONCLUSION: Patients with PD preferred combined DBS stimulation in this preliminary cohort. Future studies will address efficacy of adaptive DBS as we further define biomarkers and control policy.

Investigating the effect of an online self-compassion for weight management (SC4WM) intervention on self-compassion, eating behaviour, physical activity and body weight in adults seeking to manage weight: protocol for a randomised controlled trial.

INTRODUCTION: Individual weight management, defined as engaging in behaviours to maintain or lose weight, can improve health and well-being. However, numerous factors influence weight management outcomes, such as genetics, biology, stress, the social and physical environment. Consequently, weight management can be hard. Self-compassion, described as treating oneself kindly in times of failure or distress, has shown promise in improving weight management outcomes. The objectives of this study are twofold: (1) to examine the efficacy of an online self-compassion for weight management (SC4WM) intervention coupled with an online commercial weight management programme (WW Weight Watchers reimagined) with increasing self-compassion and improving weight management outcomes (eating behaviour, physical activity and body weight) in comparison with the WW programme only and (2) to explore whether improvements in weight management outcomes are moderated by eating restraint, weight self-stigma, perceived stress and psychological coping. METHODS AND ANALYSIS: To achieve these objectives, 240 participants seeking to manage their weight were randomised to either an online behavioural commercial weight management programme (WW) or the online WW +SC4 WM intervention. Validated measures of self-compassion, stress, weight self-stigma, eating restraint, psychological coping and weight management outcomes were administered online at baseline, 4 weeks and at a 12-week follow-up. ETHICS AND DISSEMINATION: Ethics has been granted by the University of Auckland Health Research Ethics committee. Results will be communicated in peer-review journals, conferences and a doctoral thesis. If effective in increasing self-compassion and improving weight management outcomes, the intervention could be made more widely available to supplement behavioural weight management programmes. TRIAL REGISTRATION NUMBER: ACTRN12621000580875; Pre-results.

Mechanisms of xylem hydraulic recovery after drought in Eucalyptus saligna.

The mechanisms by which woody plants recover xylem hydraulic capacity after drought stress are not well understood, particularly with regard to the role of embolism refilling. We evaluated the recovery of xylem hydraulic capacity in young Eucalyptus saligna plants exposed to cycles of drought stress and rewatering. Plants were exposed to moderate and severe drought stress treatments, with recovery monitored at time intervals from 24 h to 6 months after rewatering. The percentage loss of xylem vessels due to embolism (PLV) was quantified at each time point using microcomputed tomography with stem water potential (Ψx ) and canopy transpiration (Ec ) measured before scans. Plants exposed to severe drought stress suffered high levels of embolism (47.38% ± 10.97% PLV) and almost complete canopy loss. No evidence of embolism refilling was observed at 24 h, 1 week, or 3 weeks after rewatering despite rapid recovery in Ψx . Recovery of hydraulic capacity was achieved over a 6-month period by growth of new xylem tissue, with canopy leaf area and Ec recovering over the same period. These findings indicate that E. saligna recovers slowly from severe drought stress, with potential for embolism to persist in the xylem for many months after rainfall events.

Tapping into the physiological responses to mistletoe infection during heat and drought stress.

Mistletoes are important co-contributors to tree mortality globally, particularly during droughts. In Australia, mistletoe distributions are expanding in temperate woodlands, while their hosts have experienced unprecedented heat and drought stress in recent years. We investigated whether the excessive water use of mistletoes increased the probability of xylem emboli in a mature woodland during the recent record drought that was compounded by multiple heatwaves. We continuously recorded transpiration ($T_{SLA}$) of infected and uninfected branches from two eucalypt species over two summers, monitored stem and leaf water potentials ($\Psi $) and used hydraulic vulnerability curves to estimate percent loss in conductivity (PLC) for each species. Variations in weather (vapor pressure deficit, photosynthetically active radiation, soil water content), host species and % mistletoe foliage explained 78% of hourly $T_{SLA}$. While mistletoe acted as an uncontrollable sink for water in the host even during typical summer days, daily $T_{SLA}$ increased up to 4-fold in infected branches on hot days, highlighting the previously overlooked importance of temperature stress in amplifying water loss in mistletoes. The increased water use of mistletoes resulted in significantly decreased host $\Psi _{\rm{leaf}}$ and $\Psi _{\rm{trunk}}$. It further translated to an estimated increase of up to 11% PLC for infected hosts, confirming greater hydraulic dysfunction of infected trees that place them at higher risk of hydraulic failure. However, uninfected branches of Eucalyptus fibrosa F.Muell. had much tighter controls on water loss than uninfected branches of Eucalyptus moluccana Roxb., which shifted the risk of hydraulic failure towards an increased risk of carbon starvation for E. fibrosa. The contrasting mechanistic responses to heat and drought stress between both co-occurring species demonstrates the complexity of host-parasite interactions and highlights the challenge in predicting species-specific responses to biotic agents in a warmer and drier climate.

Pilot study of a well-being app to support New Zealand young people during the COVID-19 pandemic.

BACKGROUND: Well-being apps represent a promising and scalable approach for improving mental health outcomes in youth, especially during a global pandemic when access to face-to-face interventions may be limited. Whitu (meaning 7 in the New Zealand Maori language Te Reo) is a newly developed well-being app with 7 modules that support young people to learn and practice evidence-based coping skills, including relaxation, mindfulness, self-compassion, and goal-setting. OBJECTIVE: During this pilot, we explored the acceptability, usability, and preliminary efficacy of Whitu before refining the app for a randomized controlled trial (RCT). METHODS: We recruited 20 New Zealand young people aged 16-25 years via social media to trial the first prototype of the Whitu app over 6 weeks. Within-group differences from baseline to 2- and 6-weeks post intervention in self-reported well-being, depression, anxiety, stress, self-compassion, optimism and sleep quality were evaluated using repeated-measures ANOVA. A further 21 participants aged 16-30 years were recruited to participate in 4 focus groups to give feedback on the app's usability and cultural acceptability. Feedback was analysed using directed content analysis. RESULTS: Statistically significant improvements in anxiety (p = 0.024) and stress (p = 0.017) were observed from baseline to 2-weeks post intervention. Improvements in well-being (p = 0.021), depression (p = 0.031), anxiety (p = 0.005), and stress (p = 0.004) were also observed from baseline to 6-weeks. No statistically significant changes were seen in self-compassion, optimism, or sleep quality. Effect sizes (partial η2s) ranged from 0.25 (depression) to 0.42 (stress). Qualitative feedback comprised of five key themes, namely: factors affecting engagement, issues with functionality, preferences regarding aesthetics, effectiveness and adverse effects, and cultural acceptability. CONCLUSIONS: Our preliminary results suggest that Whitu may be an effective app for improving multiple dimensions of young people's well-being. Modifications to the look and feel, cultural content, and onboarding have been undertaken based on the qualitative feedback, and an RCT is currently underway.

Self-compassion in weight management: A systematic review.

OBJECTIVE: Self-compassion - the tendency or ability to treat oneself kindly in times of failure or distress - may be a natural fit to support individuals who struggle with weight management. However, while self-compassion shows promise with improving health behaviours, the associations self-compassion has on weight management outcomes are unclear. The objective of this systematic review was three-fold: (1) to evaluate whether self-compassion interventions can increase individual self-compassion in the context of weight management, (2) to investigate if self-compassion interventions can improve weight management outcomes, defined as healthier eating, increased physical activity, or reduced weight and finally, (3) to explore whether these benefits can be sustained over the longer term. METHODS: Following PRISMA guidelines, Scopus, PsycINFO, Medline, PubMed and Embase databases were searched. Studies including a measure of self-compassion and a self-compassion intervention reporting weight management outcomes were included. Studies in populations living with an eating disorder were excluded. The Quality Criteria Checklist from the American Dietetic Association was used to assess study quality. Prospero Registration #CRD42019146707. RESULTS: Of the 9082 records screened, a total of 20 studies met inclusion criteria. Seventeen studies reported significant increases in self-compassion post-intervention. Improvements were also found for eating behaviours (15 of 18), physical activity behaviours (6 of 9), and weight loss (6 of 11). The majority of improvements were maintained at follow-up, except for physical activity behaviours (1 of 7). CONCLUSION: Self-compassion interventions tailored to weight management outcomes demonstrate efficacy with increasing self-compassion post-intervention. Methodological weaknesses and questions about the maintenance of any improvements in weight management outcomes limit our ability to make strong conclusions. However, there is promise and clear relevance for including self-compassion interventions to enhance weight management outcomes; directions for improved intervention and study design are given.

Stability of tropical forest tree carbon-water relations in a rainfall exclusion treatment through shifts in effective water uptake depth.

Increasing severity and frequency of drought is predicted for large portions of the terrestrial biosphere, with major impacts already documented in wet tropical forests. Using a 4-year rainfall exclusion experiment in the Daintree Rainforest in northeast Australia, we examined canopy tree responses to reduced precipitation and soil water availability by quantifying seasonal changes in plant hydraulic and carbon traits for 11 tree species between control and drought treatments. Even with reduced soil volumetric water content in the upper 1 m of soil in the drought treatment, we found no significant difference between treatments for predawn and midday leaf water potential, photosynthesis, stomatal conductance, foliar stable carbon isotope composition, leaf mass per area, turgor loss point, xylem vessel anatomy, or leaf and stem nonstructural carbohydrates. While empirical measurements of aboveground traits revealed homeostatic maintenance of plant water status and traits in response to reduced soil moisture, modeled belowground dynamics revealed that trees in the drought treatment shifted the depth from which water was acquired to deeper soil layers. These findings reveal that belowground acclimation of tree water uptake depth may buffer tropical rainforests from more severe droughts that may arise in future with climate change.

Living on the edge: A continental-scale assessment of forest vulnerability to drought.

Globally, forests are facing an increasing risk of mass tree mortality events associated with extreme droughts and higher temperatures. Hydraulic dysfunction is considered a key mechanism of drought-triggered dieback. By leveraging the climate breadth of the Australian landscape and a national network of research sites (Terrestrial Ecosystem Research Network), we conducted a continental-scale study of physiological and hydraulic traits of 33 native tree species from contrasting environments to disentangle the complexities of plant response to drought across communities. We found strong relationships between key plant hydraulic traits and site aridity. Leaf turgor loss point and xylem embolism resistance were correlated with minimum water potential experienced by each species. Across the data set, there was a strong coordination between hydraulic traits, including those linked to hydraulic safety, stomatal regulation and the cost of carbon investment into woody tissue. These results illustrate that aridity has acted as a strong selective pressure, shaping hydraulic traits of tree species across the Australian landscape. Hydraulic safety margins were constrained across sites, with species from wetter sites tending to have smaller safety margin compared with species at drier sites, suggesting trees are operating close to their hydraulic thresholds and forest biomes across the spectrum may be susceptible to shifts in climate that result in the intensification of drought.

Performance of an Advanced Interferon-Gamma Release Assay for Mycobacterium tuberculosis Detection.

BACKGROUND: The LIAISON® QuantiFERON®-TB Gold Plus (QFT-Plus) assay, a fully automated chemiluminescence immunoassay (CLIA) system, has recently received FDA approval for the detection of interferon-γ (IFN-γ) on the LIAISON XL analyzer. Here, we evaluated the diagnostic performance of the LIAISON's CLIA method in comparison to the widely used ELISA method using the Qiagen QuantiFERON-TB Gold Plus Blood Collection Tubes. METHODS: Heparinized blood samples from 329 participants were categorized into 3 cohorts, including 15 with confirmed tuberculosis (TB) (active TB cohort), 129 non-TB (low-risk cohort), and 185 potential TB (mixed risk cohort). Samples were analyzed with both assays and results were interpreted according to the manufacturers' criteria. RESULTS: The LIAISON CLIA assay showed an overall agreement with the Qiagen ELISA assay in 13/14 (92.8%) samples among the active cohort, 93/95 (97.9%) among the low-risk cohort, with a Cohen's kappa value of 0.76 and 0.74, respectively. Test results for 185 mixed risk cohort participants showed 97.8% agreement between the LIAISON and the Qiagen, with 17 positive, 163 negative, and 1 indeterminate. Four samples were discrepant; 3 of these were negative on the ELISA but positive on the CLIA assay. CONCLUSION: Overall, the results were comparable (>92% agreement) in our study cohorts. In addition, our mixed risk cohort results showed an excellent agreement of 0.88 (Cohen's kappa value) between the 2 assays. These findings suggest that the automated LIAISON QFT-Plus assay has a comparable diagnostic performance to the Qiagen assay and can be used for latent TB infection (LTBI) diagnosis.

Initial determination of COVID-19 seroprevalence among outpatients and healthcare workers in Minnesota using a novel SARS-CoV-2 total antibody ELISA.

OBJECTIVES: To avoid the significant risks posed by the use of COVID-19 serology tests with supply chain constraints or poor performance characteristics, we developed an in-house SARS-CoV-2 total antibody test. Our test was compared with three commercial methods, and was used to determine COVID-19 seroprevalence among healthcare workers and outpatients in Minnesota. METHODS: Seventy-nine plasma and serum samples from 50 patients 4-69 days after symptom onset who tested positive by a SARS-CoV-2 PCR method using a nasopharyngeal (NP) swab were used to evaluate our test's clinical performance. Seropositive samples were analyzed for IgG titers in a follow-up assay. Thirty plasma and serum from 12 patients who tested negative by a SARS-CoV-2 PCR method using a nasopharyngeal (NP) swab and 210 negative pre-pandemic serum samples were also analyzed. Among samples from patients > 14 days after symptom onset, the assay had 100% clinical sensitivity and 100% clinical specificity, 100% positive predictive value and 100% negative predictive value. Analytical specificity was 99.8%, indicating minimal cross-reactivity. A screening study was conducted to ascertain COVID-19 seroprevalence among healthcare workers and outpatients in Minnesota. RESULTS: Analysis of serum collected between April 13 and May 21, 2020 indicated a COVID-19 seroprevalence of 2.96% among 1,282 healthcare workers and 4.46% among 2,379 outpatients. CONCLUSIONS: Our in-house SARS-CoV-2 total antibody test can be used to conduct reliable epidemiological studies to inform public health decisions during the COVID-19 pandemic.

Non-invasive measurement of leaf water content and pressure-volume curves using terahertz radiation.

In this paper we describe a non-invasive method of measuring leaf water content using THz radiation and combine this with psychrometry for determination of leaf pressure-volume relationships. In contrast to prior investigations using THz radiation to measure plant water status, the reported method exploits the differential absorption characteristic of THz radiation at multiple frequencies within plant leaves to determine absolute water content in real-time. By combining the THz system with a psychrometer, pressure-volume curves were generated in a completely automated fashion for the determination of leaf tissue water relations parameters including water potential at turgor loss, osmotic potential at full turgor and the relative water content at the turgor loss point. This novel methodology provides for repeated, non-destructive measurement of leaf water content and greatly increased efficiency in generation of leaf PV curves by reducing user handling time.