Pinpointing the causal influences of stomatal anatomy and behavior on minimum, operational, and maximum leaf surface conductance.

Leaf surface conductance to water vapor and CO2 across the epidermis (gleaf) strongly determines rates of gas exchange. Thus, clarifying the drivers of gleaf has important implications for resolving mechanisms of photosynthetic productivity and leaf and plant responses and tolerance to drought. It is well recognized that gleaf is a function of the conductances of the stomata (gs) and of the epidermis + cuticle (gec). Yet, controversies have arisen around the relative roles of stomatal density (d) and size (s), fractional stomatal opening (α; aperture relative to maximum) and gec in determining gleaf. Resolving the importance of these drivers is critical across the range of leaf surface conductances, from strong stomatal closure under drought (gleaf, min), to typical opening for photosynthesis (gleaf, op), to maximum achievable opening (gleaf, max). We derived equations and analyzed a compiled database of published and measured data for approximately 200 species and genotypes. On average, within and across species, higher gleaf, min was determined ten times more strongly by α and gec than by d, and negligibly by s; higher gleaf, op was determined approximately equally by α (47%) than by stomatal anatomy (45% by d, and 8% by s), and negligibly by gec; and higher gleaf, max was determined entirely by d. These findings clarify how diversity in stomatal functioning arises from multiple structural and physiological causes with importance shifting with context. The rising importance of d relative to α, from gleaf, min to gleaf, op, enables even species with low gleaf, min, which can retain leaves through drought, to possess high d and thereby achieve rapid gas exchange in periods of high water availability.

Spectral ecophysiology: hyperspectral pressure-volume curves to estimate leaf turgor loss.

Turgor loss point (TLP) is an important proxy for plant drought tolerance, species habitat suitability, and drought-induced plant mortality risk. Thus, TLP serves as a critical tool for evaluating climate change impacts on plants, making it imperative to develop high-throughput and in situ methods to measure TLP. We developed hyperspectral pressure-volume curves (PV curves) to estimate TLP using leaf spectral reflectance. We used partial least square regression models to estimate water potential (Ψ) and relative water content (RWC) for two species, Frangula caroliniana and Magnolia grandiflora. RWC and Ψ's model for each species had R2 ≥ 0.7 and %RMSE = 7-10. We constructed PV curves with model estimates and compared the accuracy of directly measured and spectra-predicted TLP. Our findings indicate that leaf spectral measurements are an alternative method for estimating TLP. F. caroliniana TLP's values were -1.62 ± 0.15 (means ± SD) and -1.62 ± 0.34 MPa for observed and reflectance predicted, respectively (P > 0.05), while M. grandiflora were -1.78 ± 0.34 and -1.66 ± 0.41 MPa (P > 0.05). The estimation of TLP through leaf reflectance-based PV curves opens a broad range of possibilities for future research aimed at understanding and monitoring plant water relations on a large scale with spectral ecophysiology.

Low baseline intraspecific variation in leaf pressure-volume traits: Biophysical basis and implications for spectroscopic sensing.

Intra-specific trait variation (ITV) plays a role in processes at a wide range of scales from organs to ecosystems across climate gradients. Yet, ITV remains rarely quantified for many ecophysiological traits typically assessed for species means, such as pressure volume (PV) curve parameters including osmotic potential at full turgor and modulus of elasticity, which are important in plant water relations. We defined a baseline "reference ITV" (ITVref ) as the variation among fully exposed, mature sun leaves of replicate individuals of a given species grown in similar, well-watered conditions, representing the conservative sampling design commonly used for species-level ecophysiological traits. We hypothesized that PV parameters would show low ITVref relative to other leaf morphological traits, and that their intraspecific relationships would be similar to those previously established across species and proposed to arise from biophysical constraints. In a database of novel and published PV curves and additional leaf structural traits for 50 diverse species, we found low ITVref for PV parameters relative to other morphological traits, and strong intraspecific relationships among PV traits. Simulation modeling showed that conservative ITVref enables the use of species-mean PV parameters for scaling up from spectroscopic measurements of leaf water content to enable sensing of leaf water potential.

Thresholds for persistent leaf photochemical damage predict plant drought resilience in a tropical rainforest.

Water stress can cause declines in plant function that persist after rehydration. Recent work has defined 'resilience' traits characterizing leaf resistance to persistent damage from drought, but whether these traits predict resilience in whole-plant function is unknown. It is also unknown whether the coordination between resilience and 'resistance' - the ability to maintain function during drought - observed globally occurs within ecosystems. For eight rainforest species, we dehydrated and subsequently rehydrated leaves, and measured water stress thresholds for declines in rehydration capacity and maximum quantum yield of photosystem II (Fv /Fm ). We tested correlations with embolism resistance and dry season water potentials (ΨMD ), and calculated safety margins for damage (ΨMD - thresholds) and tested correlations with drought resilience in sap flow and growth. Ψ thresholds for persistent declines in Fv /Fm , indicating resilience, were positively correlated with ΨMD and thresholds for leaf vein embolism. Safety margins for persistent declines in Fv /Fm , but not rehydration capacity, were positively correlated with drought resilience in sap flow. Correlations between resistance and resilience suggest that species' differences in performance during drought are perpetuated after drought, potentially accelerating shifts in forest composition. Resilience to photochemical damage emerged as a promising functional trait to characterize whole-plant drought resilience.

Persistent bacteremia predicts poor outcomes among neutropenic patients with carbapenem-resistant gram-negative bloodstream infections receiving appropriate therapy.

PURPOSE: Identifying persistent bacteremia early in patients with neutropenia may improve outcome. This study evaluated the role of follow-up blood cultures (FUBC) positivity in predicting outcomes among patients with neutropenia and carbapenem-resistant gram-negative bloodstream infections (CRGNBSI). METHODS: This retrospective cohort study conducted between December 2017 and April 2022 included patients more than 15 years old with neutropenia and CRGNBSI, who survived for ≥ 48 h, receiving appropriate antibiotic therapy and had FUBCs. Patients with polymicrobial bacteremia within 30 days were excluded. The primary outcome was 30 day mortality. Persistent bacteremia, septic shock, recovery from neutropenia, prolonged or profound neutropenia, requirement of intensive care and dialysis, and initiation of appropriate empirical therapy were also studied. RESULTS: In our study cohort of 155 patients, the 30 day mortality rate was 47.7%. Persistent bacteremia was common in our patient cohort (43.8%). Carbapenem resistant isolates identified in the study were K.pneumoniae (80%), E.coli (12.26%), P.aeruginosa (5.16%), A.baumanii (1.94%) and E.cloacae (0.65%). The median time for sending a FUBC was 2 days (IQR, 1-3 days). Patients with persistent bacteremia had higher mortality than those without (56.76% versus 32.1%; p < 0.001). Appropriate initial empirical therapy was given to 70.9%. Recovery from neutropenia occurred in 57.4% while 25.8% had prolonged or profound neutropenia. Sixty-nine percent (107/155) had septic shock and needed intensive care; 12.2% of patients required dialysis. Non-recovery from neutropenia (aHR, 4.28; 95% CI 2.53-7.23), presence of septic shock (aHR, 4.42; 95%CI 1.47-13.28), requirement of intensive care (aHR,3.12;95%CI 1.23-7.93), and persistent bacteremia (aHR,1.74; 95%CI 1.05-2.89) significantly predicted poor outcomes in multivariable analysis. CONCLUSION: FUBC showing persistent bacteremia predicted poor outcomes among neutropenic patients with carbapenem-resistant gram-negative bloodstream infections (CRGNBSI) and should be routinely reported.

Augmented Renal Clearance in Patients with Acute Ischemic Stroke: A Prospective Observational Study.

BACKGROUND: Augmented renal clearance (ARC) is a phenomenon that has been demonstrated in many subsets of critically ill patients and is characterized by a creatinine clearance (CrCl) > 130 mL/min. Prior research has examined ARC prevalence in the presence of sepsis, traumatic brain injury, subarachnoid hemorrhage, and intracranial hemorrhage. However, to our knowledge, no studies have examined whether this phenomenon occurs in patients suffering from an acute ischemic stroke (AIS). The objective of this study was to evaluate whether patients experiencing an AIS exhibit ARC, identify potential contributing factors, and examine the precision of current renal clearance estimation methods in patients with AIS experiencing ARC. METHODS: This was a single-center prospective observational study conducted in adult patients admitted to a neurocritical intensive care unit (ICU) at a community hospital. Once consent was gained, patients with an admitting diagnosis of an AIS underwent a 24-h urine collection to assess measured CrCl. The primary end point assessed for ARC, defined as a measured CrCl > 130 mL/min. The secondary end point evaluated length of stay in the neurocritical ICU. RESULTS: Twenty-eight patients met enrollment criteria, and data was analyzed for 20 patients. ARC was present in 35% of enrolled patients. Mathematical estimations of renal function were inadequate in detecting ARC manifestation. Patients experiencing ARC were associated with nonsignificantly shorter ICU length of stay. CONCLUSIONS: ARC appears to manifest in patients with AIS inconsistently. Patients experiencing ARC were associated with nonsignificantly shorter ICU length of stay.

A study on seroconversion following first & second doses of ChAdOx1 nCoV-19 vaccine in Central Kerala.

Background & objectives: Vaccination against COVID-19 induces spike protein-binding IgG antibodies, a robust correlate of protection against COVID-19. This study was undertaken to assess the humoral response after completion of both the doses of ChAdOx1 nCoV vaccine in healthcare workers (HCWs) at a tertiary care health centre in India. Methods: A cross-sectional COVID-19 vaccine-induced antibody study was conducted among HCWs. IgG antibodies against spike protein were measured at least 28 days after the first dose and the second dose of vaccination in both SARS CoV-2 naïve and recovered HCWs. Mean and median antibody titre following each dose of vaccine and its association with age, gender, co-morbidities and factors such as exercise, stress and sleep deprivation were also explored. Results: Among the 200 vaccine recipients, 91.5 per cent showed seroconversion after the first dose and 99.5 per cent after the second dose. The mean titre after the second dose was significantly higher when compared to the first dose (12.68±4.17 vs. 9.83±6.3, P=0.001). More than half (54%) had high antibody titre ≥12 S/Co (Signal/cut-off). Previous COVID-19 infection was the single most important factor influencing antibody production, where the mean titre just after a single dose [mean-17.81±5.94, median-20.5 (interquartile range [IQR]-3.7)] surpassed the titre after the second dose in SARS CoV-2 naïve individuals [mean-12.29±4.00, median-12.8 (IQR-3.7), P=0.001]. Furthermore, 28 per cent of vaccinees showed a reduction in titre after the second dose. The mean fall in titre was 2.25±1.40 and was more pronounced in males, the younger age group and those with previous COVID-19 infection. Interpretation & conclusions: ChAdOx1 nCov-19 vaccine after two doses elicited an excellent immune response. However, greater immunogenicity after the first dose was seen among those with previous COVID-19 infection, even surpassing the titre achieved by the second dose of vaccine in SARS CoV-2 naïve recipients. A fall in antibody titre after the second dose is a matter of concern and requires further studies.

COVID-19 Vaccines Portray the Bright Side of Human Creativity, But It Means Nothing until They Prove Their Worth: A Study on Seroconversion after the first Dose of Covishield Vaccine in Central Kerala.

Background: COVID-19 vaccines, we believe, have come to rescue us from the clutches of the dreaded severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). With rapid ongoing mutations, it is difficult to predict the effectiveness of seroconversion following vaccination. This study aims to find out the proportion of people with seroconversion following first dose of Covishield vaccine. Methods: Randomly selected health-care workers were followed up for SARS-CoV-2 immunoglobulin G (IgG) antibodies between 28 and 42 days after receiving their first vaccine dose. The VITROS SARS-CoV-2 IgG test (Ortho-Clinical Diagnostics, USA) with 100% specificity and > 90% sensitivity was used to assess seroconversion. Results: The first dose of vaccine induced seroconversion in 91.7% of beneficiaries. Nearly one-third (30.2%) of them had high antibody titers, and it showed a significant association with female gender (9.6 ± 5.5 vs. 7.6 ± 5.6) and younger age (P = 0.008). In addition, those with previous COVID infection showed a more robust immune response when compared to others (P = 0.001). Conclusion: Seroconversion rate of more than 90% offers a promising hope toward successful pandemic control. In the current scenario, the inability to attain the targeted coverage due to an upsurge in vaccine hesitancy, compounded with only lower proportion of seroconversion in elderly, faster rollout of the vaccines without any age limit, will help achieve the herd threshold more rapidly.

Mutualism disruption by an invasive ant reduces carbon fixation for a foundational East African ant-plant.

Invasive ants shape assemblages and interactions of native species, but their effect on fundamental ecological processes is poorly understood. In East Africa, Pheidole megacephala ants have invaded monodominant stands of the ant-tree Acacia drepanolobium, extirpating native ant defenders and rendering trees vulnerable to canopy damage by vertebrate herbivores. We used experiments and observations to quantify direct and interactive effects of invasive ants and large herbivores on A. drepanolobium photosynthesis over a 2-year period. Trees that had been invaded for ≥ 5 years exhibited 69% lower whole-tree photosynthesis during key growing seasons, resulting from interaction between invasive ants and vertebrate herbivores that caused leaf- and canopy-level photosynthesis declines. We also surveyed trees shortly before and after invasion, finding that recent invasion induced only minor changes in leaf physiology. Our results from individual trees likely scale up, highlighting the potential of invasive species to alter ecosystem-level carbon fixation and other biogeochemical cycles.

Threat appraisals, neuroticism, and intrusive memories: a robust mediational approach with replication.

Background: The appraisal of a stressor substantially influences how we adapt to it. We used an experimental paradigm to test and replicate the effects of threat appraisals on subsequent intrusive memories, as well as their moderation by neuroticism. Method: In three studies (total N = 562), participants were randomly assigned to an aversive or control video and then asked to report their threat appraisals of the video. Intrusive memories were assessed at one, three, five, and seven days. We used a robust framework for testing causal mediational effects and their magnitude, including sensitivity analyses and new effect size metrics. Results: We found that threat appraisals mediated the effect of the video on intrusive memories (studies 1-3), and for people higher in neuroticism, the causal mediational pathway was stronger (study 1 and 2). Conclusions: These findings provide methodologically strong evidence that threat appraisals have causal effects on subsequent intrusive memories and that neuroticism enhances this effect, lending empirical support to appraisal theories of posttraumatic stress disorder.

A stomatal safety-efficiency trade-off constrains responses to leaf dehydration.

Stomata, the microvalves on leaf surfaces, exert major influences across scales, from plant growth and productivity to global carbon and water cycling. Stomatal opening enables leaf photosynthesis, and plant growth and water use, whereas plant survival of drought depends on stomatal closure. Here we report that stomatal function is constrained by a safety-efficiency trade-off, such that species with greater stomatal conductance under high water availability (gmax) show greater sensitivity to closure during leaf dehydration, i.e., a higher leaf water potential at which stomatal conductance is reduced by 50% (Ψgs50). The gmax - Ψgs50 trade-off and its mechanistic basis is supported by experiments on leaves of California woody species, and in analyses of previous studies of the responses of diverse flowering plant species around the world. Linking the two fundamental key roles of stomata-the enabling of gas exchange, and the first defense against drought-this trade-off constrains the rates of water use and the drought sensitivity of leaves, with potential impacts on ecosystems.

Thresholds for leaf damage due to dehydration: declines of hydraulic function, stomatal conductance and cellular integrity precede those for photochemistry.

Given increasing water deficits across numerous ecosystems world-wide, it is urgent to understand the sequence of failure of leaf function during dehydration. We assessed dehydration-induced losses of rehydration capacity and maximum quantum yield of the photosystem II (Fv /Fm ) in the leaves of 10 diverse angiosperm species, and tested when these occurred relative to turgor loss, declines of stomatal conductance gs , and hydraulic conductance Kleaf , including xylem and outside xylem pathways for the same study plants. We resolved the sequences of relative water content and leaf water potential Ψleaf thresholds of functional impairment. On average, losses of leaf rehydration capacity occurred at dehydration beyond 50% declines of gs , Kleaf and turgor loss point. Losses of Fv /Fm occurred after much stronger dehydration and were not recovered with leaf rehydration. Across species, tissue dehydration thresholds were intercorrelated, suggesting trait co-selection. Thresholds for each type of functional decline were much less variable across species in terms of relative water content than Ψleaf . The stomatal and leaf hydraulic systems show early functional declines before cell integrity is lost. Substantial damage to the photochemical apparatus occurs at extreme dehydration, after complete stomatal closure, and seems to be irreversible.

The impact of patient information leaflets to prevent hypoglycemia in out-patients with type 2 diabetes mellitus / El impacto de los folletos de información al paciente para prevenir la hipoglucemia en pacientes ambulatorios con diabetes mellitus tipo 2

Hypoglycemia is a significant complication of intensive diabetes therapy, a true medical emergency, which requires prompt recognition and treatment to prevent organ and brain damage. Therefore, knowledge about diabetes can play an important role in maintaining glycemia control and prevent hypoglycemic complications. Aim: The aim of the study is to develop and assess the impact of patient information leaflets to prevent hypoglycemia in outpatients with type 2 diabetes mellitus and to study the effect of prescribed drugs pattern in patients. Material & Methods: This open labelled, interventional study was conducted in the endocrinology Out Patient Department (OPD) in a tertiary care hospital over a period of 9 months in 55 patients. The information was provided to patients through a developed patient information leaflet and their awareness and glycemic status were assessed by an internally institution developed vernacular language based validated questionnaire. The questionnaire with four different dimensions patient knowledge, glycemic control, compliance and life style was quantified in the study. Results: The study showed statistically significant (P<0.05) improvement in knowledge and glycemic control in male patients and in knowledge, compliance, and glycemic control for female patients. Literate patients showed more significant improvement in knowledge, compliance, life style, and glycemic control than illiterate patients. Conclusions: Results of the study suggested that pharmacist provided patient education and awareness helped type 2 diabetic hypoglycemic patients to improve knowledge and glycaemic control

La hipoglucemia es una complicación importante de la terapia intensiva de la diabetes, una verdadera emergencia médica, que requiere un reconocimiento y tratamiento rápidos para prevenir el daño cerebral y de órganos. Por lo tanto, el conocimiento sobre la diabetes puede desempeñar un papel importante en el mantenimiento del control de la glucemia y prevenir las complicaciones hipoglucémicas. Objetivo: el objetivo del estudio es desarrollar y evaluar el impacto de los folletos de información al paciente para prevenir la hipoglucemia en pacientes ambulatorios con diabetes mellitus tipo 2 y estudiar el efecto del patrón de medicamentos recetados en los pacientes. Material y métodos: Este estudio abierto de intervención abierta se realizó en el Departamento de pacientes ambulatorios (OPD) de endocrinología en un hospital de atención terciaria durante un período de 9 meses en 55 pacientes. La información se proporcionó a los pacientes a través de un folleto de información al paciente y su conocimiento y estado glucémico se evaluaron mediante un cuestionario validado basado en el lenguaje vernáculo desarrollado internamente en una institución. El cuestionario con cuatro dimensiones diferentes de conocimiento del paciente, control glucémico, cumplimiento y estilo de vida se cuantificó en el estudio. Resultados: El estudio mostró una mejora, estadísticamente significativa (P <0,05), en el conocimiento y el control glucémico en pacientes masculinos y en el conocimiento, el cumplimiento y el control glucémico en pacientes femeninos. Los pacientes alfabetizados mostraron una mejora más significativa en el conocimiento, el cumplimiento, el estilo de vida y el control glucémico que los pacientes analfabetos. Conclusiones: Los resultados del estudio sugirieron que el farmacéutico brindó a los pacientes con hipoglucemia diabética tipo 2 información y conciencia para mejorar el conocimiento y el control glucémico

Curcumin-galactomannosides mitigate alcohol-induced liver damage by inhibiting oxidative stress, hepatic inflammation, and enhance bioavailability on TLR4/MMP events compared to curcumin.

Alcoholic liver diseases are classified as one of the major reasons for worldwide morbidity and mortality. Curcuminoids exhibit a wide range of pharmacological activities that are beneficial for health, including hepatoprotective effects, but its clinical significance is limited due to poor oral bioavailability. In the present study, a novel formulation of curcumin as curcumin-galactomannosides (CGM) with enhanced oral bioavailability alleviated alcohol-induced liver damage in wistar rats with an increased potency compared to the unformulated natural curcuminoids (CM). Ethanol administration significantly elevated liver toxicity markers, lipid peroxidation and inflammatory markers with a simultaneous reduction in antioxidant defenses. Supplementation of CGM reversed all of the pathological effects of alcohol administration, almost close to the normal level, when compared with CM. Histopathology of liver tissue also confirmed the better protective effect of CGM, indicating the enhancement in antioxidant and anti-inflammatory effects as a function of bioavailability.

Identifying adherence barriers to oral endocrine therapy among breast cancer survivors.

PURPOSE: Approximately 70-80% of breast cancers are hormone receptor-positive (HR+). OET, including tamoxifen and aromatase inhibitors, is considered standard adjuvant therapy for HR+ breast cancer. Despite demonstrated benefits, nearly half of patients are non-adherent and over two-thirds discontinue therapy before the recommended 5 years. Our objective was to identify and summarize literature-reported barriers associated with non-adherence/non-persistence to OET among breast cancer survivors. METHODS: A PUBMED literature search was conducted using the following terms: 'breast cancer,' 'oral endocrine therapy' or 'Tamoxifen' or 'Aromatase Inhibitors,' 'adherence,' or 'barriers.' The search was restricted to past six years. The abstracts of each result were reviewed and categorized as either patient-reported or physician-reported. All patient- and physician-reported factors that affected adherence and persistence were listed and grouped together into the three main categories: Socio-demographic and medical parameters, general psychosocial parameters, and psychosocial parameters related to OET. RESULTS: A total of 320 articles were identified, of which 19 met inclusion criteria. Adverse drug reactions were the most commonly reported barrier but were generally underreported among physicians. Among patient-reported barriers, common social-demographic and medical parameters were age, comorbidity, and financial status. General psychosocial variables were lack of patient-provider communication, depressive symptoms, and lack of perceived self-efficacy. Treatment toxicity was the most commonly reported psychosocial parameter related to OET. CONCLUSION: The determinants of non-adherence and non-persistence are multi-dimensional and influenced by several factors. The three categories of adherence barriers should be evaluated and considered when designing future interventions to enhance OET adherence for a tailored approach.

Embracing 3D Complexity in Leaf Carbon-Water Exchange.

Leaves are a nexus for the exchange of water, carbon, and energy between terrestrial plants and the atmosphere. Research in recent decades has highlighted the critical importance of the underlying biophysical and anatomical determinants of CO2 and H2O transport, but a quantitative understanding of how detailed 3D leaf anatomy mediates within-leaf transport has been hindered by the lack of a consensus framework for analyzing or simulating transport and its spatial and temporal dynamics realistically, and by the difficulty of measuring within-leaf transport at the appropriate scales. We discuss how recent technological advancements now make a spatially explicit 3D leaf analysis possible, through new imaging and modeling tools that will allow us to address long-standing questions related to plant carbon-water exchange.

Evolution of leaf structure and drought tolerance in species of Californian Ceanothus.

PREMISE OF THE STUDY: Studies across diverse species have established theory for the contribution of leaf traits to plant drought tolerance. For example, species in more arid climates tend to have smaller leaves of higher vein density, higher leaf mass per area, and more negative osmotic potential at turgor loss point (πTLP ). However, few studies have tested these associations for species within a given lineage that have diversified across an aridity gradient. METHODS: We analyzed the anatomy and physiology of 10 Ceanothus (Rhamnaceae) species grown in a common garden for variation between and within "wet" and "dry" subgenera (Ceanothus and Cerastes, respectively) and analyzed a database for 35 species for leaf size and leaf mass per area (LMA). We used a phylogenetic generalized least squares approach to test hypothesized relationships among traits, and of traits with climatic aridity in the native range. We also tested for allometric relationships among anatomical traits. KEY RESULTS: Leaf form, anatomy, and drought tolerance varied strongly among species within and between subgenera. Cerastes species had specialized anatomy including hypodermis and encrypted stomata that may confer superior water storage and retention. The osmotic potentials at turgor loss point (πTLP ) and full turgor (πo ) showed evolutionary correlations with the aridity index (AI) and precipitation of the 10 species' native distributions, and LMA with potential evapotranspiration for the 35 species in the larger database. We found an allometric correlation between upper and lower epidermal cell wall thicknesses, but other anatomical traits diversified independently. CONCLUSIONS: Leaf traits and drought tolerance evolved within and across lineages of Ceanothus consistently with climatic distributions. The πTLP has signal to indicate the evolution of drought tolerance within small clades.