Search

The response of tropical trees and tree communities to climate change is crucial for the carbon storage and biodiversity of the terrestrial biosphere. Trees in tropical montane rainforests (TMFs) are considered particularly vulnerable to climate change, but this hypothesis remains poorly evaluated due to data scarcity. To reduce the knowledge gap on the response of TMFs trees to warming, we established a field experiment along a 1300–2400 m elevation gradient in Rwanda. Twenty tree species native to montane forests in East and Central Africa were planted in multispecies plots at three sites along the gradient. They have overlapping distributions but primarily occur in either transitional rainforest (1600–2000 m a.s.l) or mid elevation TMF (2000–3000 m a.s.l.), with both early- (ES) and late-successional (LS) species represented in each elevation origin group. Tree growth (diameter and height) and survival were monitored regularly over two years. We found that ES species, especially from lower elevations, grew faster at warmer sites while several of the LS species, especially from higher elevations, did not respond or grew slower. Moreover, a warmer climate increased tree mortality in LS species, but not much in ES species. ES species with transitional rainforest origin strongly increased in proportion of stand basal area at warmer sites, while TMF species declined, suggesting that lower-elevation ES species will have an advantage over higher-elevation species in a warming climate. The risk of higher-elevation and LS species to become outcompeted by lower-elevation and ES species in a warmer climate has important implications for biodiversity and carbon storage of Afromontane forests.

Summary Tropical climates are getting warmer, with pronounced dry periods in large areas. The productivity and climate feedbacks of future tropical forests depend on the ability of trees to acclimate their physiological processes, such as leaf dark respiration (R d), to these new conditions. However, knowledge on this is currently limited due to data scarcity.We studied the impact of growth temperature on R d and its dependency on net photosynthesis (A n), leaf nitrogen (N) and phosphorus (P) contents, and leaf mass per unit area (LMA) in 16 early‐successional (ES) and late‐successional (LS) tropical tree species in multispecies plantations along an elevation gradient (Rwanda TREE project). Moreover, we explored the effect of drought on R d in one ES and one LS species.Leaf R d at 20°C decreased at warmer sites, regardless if it was expressed per unit leaf area, mass, N or P. This acclimation resulted in an 8% and a 28% decrease in R d at prevailing nighttime temperatures in trees at the intermediate and warmest sites, respectively. Moreover, drought reduced R d, particularly in the ES species and at the coolest site.Thermal acclimation of R d is complete or overcompensatory and independent of changes in leaf nutrients or LMA in African tropical trees.

Interpreting phloem carbohydrate or xylem tissue carbon isotopic composition as measures of water-use efficiency or past tree productivity requires in-depth knowledge of the factors altering the isotopic composition within the pathway from ambient air to phloem contents and tree ring. One of least understood of these factors is mesophyll conductance (g(m)). We formulated a dynamic model describing the leaf photosynthetic pathway including seven alternative g(m) descriptions and a simple transport of sugars from foliage down the trunk. We parameterised the model for a boreal Scots pine stand and compared simulated g(m) responses with weather variations. We further compared the simulated delta C-13 of new photosynthates among the different g(m) descriptions and against measured phloem sugar delta C-13. Simulated g(m) estimates of the seven descriptions varied according to weather conditions, resulting in varying estimates of phloem delta C-13 during cold/moist and warm/dry periods. The model succeeded in predicting a drought response and a postdrought release in phloem sugar delta C-13 indicating suitability of the model for inverse prediction of leaf processes from phloem isotopic composition. We suggest short-interval phloem sampling during and after extreme weather conditions to distinguish between mesophyll conductance drivers for future model development.

Leaf morphological traits vary along climate gradients, but it is currently unclear to what extent this results from acclimation rather than adaptation. Knowing so is important for predicting the functioning of long-lived organisms, such as trees, in a rapidly changing climate. We investigated the leaf morphological warming responses of 18 tropical tree species with early (ES) abd late (LS) successional strategies, planted at three sites along an elevation gradient from 2400 m a.s.l. (15.2 °C mean temperature) to 1300 m a.s.l. (20.6 °C mean temperature) in Rwanda. Leaf size expressed as leaf area (LA) and leaf mass per area (LMA) decreased, while leaf width-to-length ratio (W/L) increased with warming, but only for one third to half of the species. While LA decreased in ES species, but mostly not in LS species, changes in LMA and leaf W/L were common in both successional groups. ES species had lower LMA and higher LA and leaf W/L compared to LS species. Values of LMA and LA of juvenile trees in this study were mostly similar to corresponding data on four mature tree species in another elevation-gradient study in Rwanda, indicating that our results are applicable also to mature forest trees. We conclude that leaf morphological responses to warming differ greatly between both successional groups and individual species, with potential consequences for species competitiveness and community composition in a warmer climate.

Introduction The treatment strategies for a 42‐year‐old female index patient with moderate Graves’ disease (GD) vary according to several international surveys. The important question whether surveys of treatment preferences in theoretical patient cases also match how real patients are treated has not yet been addressed. Materials and Methods From a Swedish cohort of 1186 GD patients (TT‐12 cohort), 27 women were identified using the same criteria as from the index patient surveys from the European and American Thyroid Associations. This ‘index patient cohort’ was age 40–45, otherwise healthy female, with two children and uncomplicated GD. The applied first‐line treatment of the patients in the index cohort, together with its variations, was compared with the treatment preferences according to international surveys. A comparison with the TT‐12 cohort was also performed. Results In the ‘Index cohort’, 77.8% were treated with antithyroid drugs (ATD), and 22.2% were treated with radioiodine (131I). This preference for ATD is in line with most countries/regions, with the exception of USA and the Middle East/North Africa, where 131I was preferred. The distribution of treatment in the TT‐12 cohort did not significantly differ from the index cohort. ATD was the preferred treatment in male and young (age 19–22) patients, as was RAI in old (age 69–73) patients. The age‐related, but not the gender‐related, cases differed significantly from the entire TT‐12 cohort. Conclusion The treatment choice in an index patient in Sweden seems in line with European practice, where ATD is the preferred first choice. This differs compared to US and North African survey intentions, where 131I is more often used. Age more than gender influences the treatment choice of GD patients. This is, to our best knowledge, the first time an index patient from ‘real life’ has been presented and compared to treatment preferences of international thyroid association surveys., According to several international surveys, the treatment strategies for a 42‐year‐old female index patient with moderate Graves’ disease vary considerably. In this study, the correlation of treatment strategies between patients from the Swedish thyrotoxicosis 2012 study cohort, who met the criteria for the index patient and its variations, and the theoretical index patient in international surveys is examined and compared. This is in order to allow a reasonable comparison with and, if possible, to validate the international surveys.

The growing detection of papillary thyroid microcarcinomas (PTMCs) is paralleled by an increase in surgical procedures. Due to the frequent indolent nature, cost, and risk of surgery, active surveillance (AS) and ultrasound-guided minimally invasive treatments (MITs) are in suitable cases of incidental PTMC proposed as alternatives to thyroidectomy. Surgery and radioiodine are the established treatments for relapsing cervical differentiated thyroid carcinoma (DTC) metastases. But radioiodine refractoriness, risk of surgical complications, adverse influence on quality of life, or declining repeat surgery have led to AS and MIT being considered as alternatives for slow-growing DTC nodal metastases. Also, for distant radioiodine-refractory metastases not amenable to surgery, MIT is proposed as part of a multimodality therapeutic approach. The European Thyroid Association and the Cardiovascular and Interventional Radiological Society of Europe commissioned these guidelines for the appropriate use of MIT. Based on a systematic PubMed search, an evidence-based approach was applied, and both knowledge and practical experience of the panelists were incorporated to develop the manuscript and the specific recommendations. We recommend that when weighing between surgery, radioiodine, AS, or MIT for DTC, a multidisciplinary team including members with expertise in interventional radiology assess the demographic, clinical, histological, and imaging characteristics for appropriate selection of patients eligible for MIT. Consider TA in low-risk PTMC patients who are at surgical risk, have short life expectancy, relevant comorbidities, or are unwilling to undergo surgery or AS. As laser ablation, radiofrequency ablation, and microwave ablation are similarly safe and effective thermal ablation (TA) techniques, the choice should be based on the specific competences and resources of the centers. Use of ethanol ablation and high-intensity focused ultrasound is not recommended for PTMC treatment. Consider MIT as an alternative to surgical neck dissection in patients with radioiodine refractory cervical recurrences who are at surgical risk or decline further surgery. Factors that favor MIT are previous neck dissection, presence of surgical complications, small size metastases, and

Background: Small intestinal neuroendocrine tumors (SI-NETs) are difficult to diagnose in the early stage of disease. Current blood biomarkers such as chromogranin A (CgA) and 5-hydroxyindolacetic acid have low sensitivity (SEN) and specificity (SPE). This is a first preplanned interim analysis (Nordic non-interventional, prospective, exploratory, EXPLAIN study [NCT02630654]). Its objective is to investigate if a plasma protein multi-biomarker strategy can improve diagnostic accuracy (ACC) in SI-NETs. Methods: At the time of diagnosis, before any disease-specific treatment was initiated, blood was collected from patients with advanced SI-NETs and 92 putative cancer-related plasma proteins from 135 patients were analyzed and compared with the results of age- and sex-matched controls (n = 143), using multiplex proximity extension assay and machine learning techniques. Results: Using a random forest model including 12 top ranked plasma proteins in patients with SI-NETs, the multi-biomarker strategy showed SEN and SPE of 89 and 91%, respectively, with negative predictive value (NPV) and positive predictive value (PPV) of 90 and 91%, respectively, to identify patients with regional or metastatic disease with an area under the receiver operator characteristic curve (AUROC) of 99%. In 30 patients with normal CgA concentrations, the model provided a diagnostic SPE of 98%, SEN of 56%, and NPV 90%, PPV of 90%, and AUROC 97%, regardless of proton pump inhibitor intake. Conclusion: This interim analysis demonstrates that a multi-biomarker/machine learning strategy improves diagnostic ACC of patients with SI-NET at the time of diagnosis, especially in patients with normal CgA levels. The results indicate that this multi-biomarker strategy can be useful for early detection of SI-NETs at presentation and conceivably detect recurrence after radical primary resection.

International audience; Differences in photosynthetic capacity among tree species and tree functional types are currently assumed to be largely driven by variation in leaf nutrient content, particularly nitrogen (N). However, recent studies indicate that leaf N content is often a poor predictor of variation in photosynthetic capacity in tropical trees. In this study, we explored the relative importance of area-based total leaf N content (N tot) and within-leaf N allocation to photosynthetic capacity versus light-harvesting in controlling the variation in photosynthetic capacity (i.e. V cmax , J max) among mature trees of 12 species belonging to either early (ES) or late successional (LS) groups growing in a tropical montane rainforest in Rwanda, Central Africa. Photosynthetic capacity at a common leaf temperature of 25˚C (i.e. maximum rates of Rubisco carboxylation, V cmax25 and of electron transport, J max25) was higher in ES than in LS species (+ 58% and 68% for V cmax25 and J max25 , respectively). While N tot did not significantly differ between successional groups, the photosynthetic dependency on N tot was markedly different. In ES species, V cmax25 was strongly and positively related to N tot but this was not the case in LS species. However, there was no significant trade-off between relative leaf N investments in compounds maximizing photosynthetic capacity versus compounds maximizing light harvesting. Both leaf dark respiration at 25˚C (+ 33%) and, more surprisingly, apparent photosynthetic quantum yield (+ 35%) was higher in ES than in LS species. Moreover, R d25 was positively related to N tot for both ES and LS species. Our results imply that efforts to quantify carbon fluxes of tropical montane rainforests would be improved if they considered contrasting within-leaf N allocation and photosynthetic N tot dependencies between species with different successional strategies.

ObjectiveColon cancer surgery remains associated with substantial postoperative morbidity and mortality despite advances in surgical techniques and care. The trauma of surgery triggers adrenergic hyperactivation which drives adverse stress responses. We hypothesised that outcome benefits are gained by reducing the effects of hyperadrenergic activity with beta-blocker therapy in patients undergoing colon cancer surgery. This study aims to test this hypothesis.DesignRetrospective cohort study.Setting and participantsThis is a nationwide study which includes all adult patients undergoing elective colon cancer surgery in Sweden over 10 years. Patient data were collected from the Swedish Colorectal Cancer Registry. The national drugs registry was used to obtain information about beta-blocker use. Patients were subdivided into exposed and unexposed groups. The association between beta-blockade, short-term and long-term mortality was evaluated using Poisson regression, Kaplan-Meier curves and Cox regression.Primary and secondary outcomesPrimary outcome of interest was 1-year all-cause mortality. Secondary outcomes included 90-day all-cause and 5-year cancer-specific mortality.ResultsThe study included 22 337 patients of whom 36.1% were prescribed preoperative beta-blockers. Survival was higher in patients on beta-blockers up to 1 year after surgery despite this group being significantly older and of higher comorbidity. Regression analysis demonstrated significant reductions in 90-day deaths (IRR 0.29, 95% CI 0.24 to 0.35, pConclusionPreoperative beta-blockade is associated with significant reductions in postoperative short-term and long-term mortality following elective colon cancer surgery. Its potential prophylactic effect warrants further interventional studies to determine whether beta-blockade can be used as a way of improving outcomes for this patient group.

Mesenteric fibrosis (MF) constitutes an underrecognized sequela in patients with small intestinal neuroendocrine neoplasms (SI-NENs), often complicating the disease clinical course. The aim of the present systematic review, carried out by Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology, is to provide an update in evolving aspects of MF pathogenesis and its clinical management in SI-NENs. Complex and dynamic interactions are present in the microenvironment of tumor deposits in the mesentery. Serotonin, as well as the signaling pathways of certain growth factors play a pivotal, yet not fully elucidated role in the pathogenesis of MF. Clinically, MF often results in significant morbidity by causing either acute complications, such as intestinal obstruction and/or acute ischemia or more chronic conditions involving abdominal pain, venous stasis, malabsorption and malnutrition. Surgical resection in patients with locoregional disease only or symptomatic distant stage disease, as well as palliative minimally invasive interventions in advanced inoperable cases seem clinically meaningful, whereas currently available systemic and/or targeted treatments do not unequivocally affect the development of MF in SI-NENs. Increased awareness and improved understanding of the molecular pathogenesis of MF in SI-NENs may provide better diagnostic and predictive tools for its timely recognition and intervention and also facilitates the development of agents targeting MF.

The role of primary tumor resection in patients with pancreatic neuroendocrine neoplasms (PanNENs) and unresectable distant metastases remains controversial. We aimed to evaluate the effect of palliative primary tumor resection (PPTR) on overall survival (OS) in this setting. We searched the MEDLINE, Embase, Cochrane Library, Web of Science and SCOPUS databases up to January 2020 and used the Newcastle–Ottawa scale (NOS) criteria to assess quality/risk of bias. A total of 5661 articles were screened. In 10 studies, 5551 unique patients with stage IV PanNEN and unresectable metastases were included. The five-year OS for PanNEN patients undergoing PPTR in stage IV was 56.6% vs. 23.9% in the non-surgically treated patients (random effects relative risk (RR): 1.70; 95% CI: 1.53–1.89). Adjusted analysis of pooled hazard ratios (HR) confirmed longer OS in PanNEN patients undergoing PPTR (random effects HR: 2.67; 95% CI: 2.24–3.18). Cumulative OS analysis confirmed an attenuated survival benefit over time. The complication rate of PPTR was as high as 27%. In conclusion, PPTR may exert a survival benefit in stage IV PanNEN. However, the included studies were subject to selection bias, and special consideration should be given to PPTR anchored to a multimodal treatment strategy. Further longitudinal studies are warranted, with long-term follow-up addressing the survival outcomes associated with surgery in stage IV disease.

The Bethesda system for cytopathology (TBSRTC) is a 6-tier diagnostic framework developed to standardize thyroid cytopathology reporting. The aim of this study was to determine the risk of malignancy (ROM) for each Bethesda category. Thyroidectomy-related data from 314 facilities in 22 countries were entered into the following outcome registries: CESQIP (North America), Eurocrine (Europe), SQRTPA (Sweden) and UKRETS (UK). Demographic, cytological, pathologic and extent of surgery data were mapped into one dataset and analyzed. Out of 41,294 thyroidectomy patient entries from January 1, 2015, to June 30, 2017, 21,746 patients underwent both thyroid FNA and surgery. A comparison of cytology and surgical pathology data demonstrated a ROM for Bethesda categories 1 to 6 of 19.2%, 12.7%, 31.9%, 31.4%, 77.8% and 96.0%, respectively. Male patients had a higher rate of malignancy for every Bethesda category. Secondary analysis demonstrated a high ROM in male patients with Bethesda 3 category aged 31–35 years (52.1%, 95% confidence interval (CI) 37.9–66.2%), aged 36–40 years (55.9%, 95% CI 39.2–72.6%) and aged 41–45 years (46.9%, 95% CI 33–60.9%). Patients with Bethesda 5 and 6 scores were more likely to undergo total thyroidectomy (65.9% and 84.6%); for patients with Bethesda scores 2 and 3, a higher percentage of females underwent total thyroidectomy compared to males in spite of a higher ROM for males. These data demonstrate that Bethesda categories 1–4 are associated with a higher ROM compared to the first edition of TBSRTC, especially in male patients, and validate findings from the second edition of TBSRTC.

International audience; The temperature response of photosynthesis is one of the key factors determining predicted responses to warming in global vegetation models (GVMs). The response may vary geographically, owing to genetic adaptation to climate, and temporally, as a result of acclimation to changes in ambient temperature. Our goal was to develop a robust quantitative global model representing acclimation and adaptation of photosynthetic temperature responses. We quantified and modelled key mechanisms responsible for photosynthetic temperature acclimation and adaptation using a global dataset of photosynthetic CO2 response curves, including data from 141 C3 species from tropical rainforest to Arctic tundra. We separated temperature acclimation and adaptation processes by considering seasonal and common‐garden datasets, respectively. The observed global variation in the temperature optimum of photosynthesis was primarily explained by biochemical limitations to photosynthesis, rather than stomatal conductance or respiration. We found acclimation to growth temperature to be a stronger driver of this variation than adaptation to temperature at climate of origin. We developed a summary model to represent photosynthetic temperature responses and showed that it predicted the observed global variation in optimal temperatures with high accuracy. This novel algorithm should enable improved prediction of the function of global ecosystems in a warming climate.

Yan-Shih Lin [et al.].- Received 16 August 2014, Accepted 16 January 2015, Published online 02 March 2015, Stomatal conductance (gs) is a key land-surface attribute as it links transpiration, the dominant component of global land evapotranspiration, and photosynthesis, the driving force of the global carbon cycle. Despite the pivotal role of gs in predictions of global water and carbon cycle changes, a global-scale database and an associated globally applicable model of gs that allow predictions of stomatal behaviour are lacking. Here, we present a database of globally distributed gs obtained in the field for a wide range of plant functional types (PFTs) and biomes. We find that stomatal behaviour differs among PFTs according to their marginal carbon cost of water use, as predicted by the theory underpinning the optimal stomatal model1 and the leaf and wood economics spectrum2, 3. We also demonstrate a global relationship with climate. These findings provide a robust theoretical framework for understanding and predicting the behaviour of gs across biomes and across PFTs that can be applied to regional, continental and global-scale modelling of ecosystem productivity, energy balance and ecohydrological processes in a future changing climate.

IntroductionAutoimmunity against the TSH receptor is a key pathogenic element in Graves' disease. The autoimmune aberration may be modified by therapy of the hyperthyroidism.ObjectiveTo compare the effects of the common types of therapy for Graves' hyperthyroidism on TSH-receptor autoimmunity.MethodsPatients with newly diagnosed Graves' hyperthyroidism aged 20–55 years were randomized to medical therapy, thyroid surgery, or radioiodine therapy (radioiodine was only given to patients ≥35 years of age). l-thyroxine (l-T4) was added to therapy as appropriate to keep patients euthyroid. Anti-thyroid drugs were withdrawn after 18 months of therapy. TSH-receptor antibodies (TRAb) in serum were measured before and for 5 years after the initiation of therapy.ResultsMedical therapy (n=48) and surgery (n=47) were followed by a gradual decrease in TRAb in serum, with the disappearance of TRAb in 70–80% of the patients after 18 months. Radioiodine therapy (n=36) led to a 1-year long worsening of autoimmunity against the TSH receptor, and the number of patients entering remission of TSH-receptor autoimmunity with the disappearance of TRAb from serum during the following years was considerably lower than with the other types of therapy.ConclusionThe majority of patients with Graves' disease gradually enter remission of TSH-receptor autoimmunity during medical or after surgical therapy, with no difference between the types of therapy. Remission of TSH-receptor autoimmunity after radioiodine therapy is less common.

Temperate and boreal forest ecosystems contain a large part of the carbon stored on land, in the form of both biomass and soil organic matter. Increasing atmospheric [CO2], increasing temperature, elevated nitrogen deposition and intensified management will change this C store. Well documented single-factor responses of net primary production are: higher photosynthetic rate (the main [CO2] response); increasing length of growing season (the main temperature response); and higher leaf-area index (the main N deposition and partly [CO2] response). Soil organic matter will increase with increasing litter input, although priming may decrease the soil C stock initially, but litter quality effects should be minimal (response to [CO2], N deposition, and temperature); will decrease because of increasing temperature; and will increase because of retardation of decomposition with N deposition, although the rate of decomposition of high-quality litter can be increased and that of low-quality litter decreased. Single-factor responses can be misleading because of interactions between factors, in particular those between N and other factors, and indirect effects such as increased N availability from temperature-induced decomposition. In the long term the strength of feedbacks, for example the increasing demand for N from increased growth, will dominate over short-term responses to single factors. However, management has considerable potential for controlling the C store.

A whole-tree chamber (WTC) system was installed at Flakaliden in northern Sweden to examine the long-term physiological responses of field-grown 40-year-old Norway spruce trees [Picea abies (L.) Karst.] to climate change. The WTCs were designed as large cuvettes to allow the net tree-level CO(2) and water fluxes to be measured on a continuous basis. A total of 12 WTCs were used to impose combinations of atmospheric carbon dioxide concentration, [CO(2)], and air temperature treatments. The air inside the ambient and elevated [CO(2)] WTCs was maintained at 365 and 700 micromol mol(-1), respectively. The air temperature inside the ambient temperature WTCs tracked air temperature outside the WTCs. Elevated temperatures were altered on a monthly time-step and ranged between +2.8 and +5.6 degrees C above ambient temperature. The system allowed continuous, long-term measurement of whole-tree photosynthesis, night-time respiration and transpiration. The performance of the WTCs was assessed using winter and spring data sets. The ability of the WTC system to measure tree-level physiological responses is demonstrated. All WTCs displayed a high level of control over tracking of air temperatures. The set target of 365 micromol mol(-1) in the ambient [CO(2)] chambers was too low to be maintained during winter because of tree dormancy and the high natural increase in [CO(2)] over winter at high latitudes such as the Flakaliden site. Accurate control over [CO(2)] in the ambient [CO(2)] chambers was restored during the spring and the system maintained the elevated [CO(2)] target of 700 micromol mol(-1) for both measurement periods. Air water vapour deficit (VPD) was accurately tracked in ambient temperature WTCs. However, as water vapour pressure in all 12 WTCs was maintained at the level of non-chambered (reference) air, VPD of elevated temperature WTCs was increased.