The contribution of insects to global forest deadwood decomposition

The amount of carbon stored in deadwood is equivalent to about 8 per cent of the global forest carbon stocks. The decomposition of deadwood is largely governed by climate with decomposer groups—such as microorganisms and insects—contributing to variations in the decomposition rates. At the global scale, the contribution of insects to the decomposition of deadwood and carbon release remains poorly understood. Here we present a field experiment of wood decomposition across 55 forest sites and 6 continents. We find that the deadwood decomposition rates increase with temperature, and the strongest temperature effect is found at high precipitation levels. Precipitation affects the decomposition rates negatively at low temperatures and positively at high temperatures. As a net effect—including the direct consumption by insects and indirect effects through interactions with microorganisms—insects accelerate the decomposition in tropical forests (3.9% median mass loss per year). In temperate and boreal forests, we find weak positive and negative effects with a median mass loss of 0.9 per cent and −0.1 per cent per year, respectively. Furthermore, we apply the experimentally derived decomposition function to a global map of deadwood carbon synthesized from empirical and remote-sensing data, obtaining an estimate of 10.9 ± 3.2 petagram of carbon per year released from deadwood globally, with 93 per cent originating from tropical forests. Globally, the net effect of insects may account for 29 per cent of the carbon flux from deadwood, which suggests a functional importance of insects in the decomposition of deadwood and the carbon cycle

Response to Comments on "Productivity Is a Poor Predictor of Plant Species Richness"

Pan et al. claim that our results actually support a strong linear positive relationship between productivity and richness, whereas Fridley et al. contend that the data support a strong humped relationship. These responses illustrate how preoccupation with bivariate patterns distracts from a deeper understanding of the multivariate mechanisms that control these important ecosystem properties

Chlorhexidine versus povidone–iodine skin antisepsis before upper limb surgery (CIPHUR) : an international multicentre prospective cohort study

Introduction Surgical site infection (SSI) is the most common and costly complication of surgery. International guidelines recommend topical alcoholic chlorhexidine (CHX) before surgery. However, upper limb surgeons continue to use other antiseptics, citing a lack of applicable evidence, and concerns related to open wounds and tourniquets. This study aimed to evaluate the safety and effectiveness of different topical antiseptics before upper limb surgery. Methods This international multicentre prospective cohort study recruited consecutive adults and children who underwent surgery distal to the shoulder joint. The intervention was use of CHX or povidone–iodine (PVI) antiseptics in either aqueous or alcoholic form. The primary outcome was SSI within 90 days. Mixed-effects time-to-event models were used to estimate the risk (hazard ratio (HR)) of SSI for patients undergoing elective and emergency upper limb surgery. Results A total of 2454 patients were included. The overall risk of SSI was 3.5 per cent. For elective upper limb surgery (1018 patients), alcoholic CHX appeared to be the most effective antiseptic, reducing the risk of SSI by 70 per cent (adjusted HR 0.30, 95 per cent c.i. 0.11 to 0.84), when compared with aqueous PVI. Concerning emergency upper limb surgery (1436 patients), aqueous PVI appeared to be the least effective antiseptic for preventing SSI; however, there was uncertainty in the estimates. No adverse events were reported. Conclusion The findings align with the global evidence base and international guidance, suggesting that alcoholic CHX should be used for skin antisepsis before clean (elective upper limb) surgery. For emergency (contaminated or dirty) upper limb surgery, the findings of this study were unclear and contradict the available evidence, concluding that further research is necessary

Plant species' origin predicts dominance and response to nutrient enrichment and herbivores in global grasslands

Exotic species dominate many communities; however the functional significance of species’ biogeographic origin remains highly contentious. This debate is fuelled in part by the lack of globally replicated, systematic data assessing the relationship between species provenance, function and response to perturbations. We examined the abundance of native and exotic plant species at 64 grasslands in 13 countries, and at a subset of the sites we experimentally tested native and exotic species responses to two fundamental drivers of invasion, mineral nutrient supplies and vertebrate herbivory. Exotic species are six times more likely to dominate communities than native species. Furthermore, while experimental nutrient addition increases the cover and richness of exotic species, nutrients decrease native diversity and cover. Native and exotic species also differ in their response to vertebrate consumer exclusion. These results suggest that species origin has functional significance, and that eutrophication will lead to increased exotic dominance in grasslands

Predicting invasion in grassland ecosystems: is exotic dominance the real embarrassment of richness?

Invasions have increased the size of regional species pools, but are typically assumed to reduce native diversity. However, global-scale tests of this assumption have been elusive because of the focus on exotic species richness, rather than relative abundance. This is problematic because low invader richness can indicate invasion resistance by the native community or, alternatively, dominance by a single exotic species. Here, we used a globally replicated study to quantify relationships between exotic richness and abundance in grass-dominated ecosystems in 13 countries on six continents, ranging from salt marshes to alpine tundra. We tested effects of human land use, native community diversity, herbivore pressure, and nutrient limitation on exotic plant dominance. Despite its widespread use, exotic richness was a poor proxy for exotic dominance at low exotic richness, because sites that contained few exotic species ranged from relatively pristine (low exotic richness and cover) to almost completely exotic-dominated ones (low exotic richness but high exotic cover). Both exotic cover and richness were predicted by native plant diversity (native grass richness) and land use (distance to cultivation). Although climate was important for predicting both exotic cover and richness, climatic factors predicting cover (precipitation variability) differed from those predicting richness (maximum temperature and mean temperature in the wettest quarter). Herbivory and nutrient limitation did not predict exotic richness or cover. Exotic dominance was greatest in areas with low native grass richness at the site- or regional-scale. Although this could reflect native grass displacement, a lack of biotic resistance is a more likely explanation, given that grasses comprise the most aggressive invaders. These findings underscore the need to move beyond richness as a surrogate for the extent of invasion, because this metric confounds monodominance with invasion resistance. Monitoring species’ relative abundance will more rapidly advance our understanding of invasions.This is the publisher’s final pdf. The published article is copyrighted by John Wiley & Sons Ltd and can be found at: http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2486

Anti-angiogenic efficacy of Bevacizumab alone and in combination with a dual PI3K/mTOR inhibitor in an orthotopic model of malignant glioma: A multimodal neuro-imaging approach

The treatment of glioblastoma represents one of the main oncological challenges of the 21st century. Despite intensive therapeutic efforts, the median survival remains 15-18 months. Initially, we conducted a single center retrospective study, at the National Neurosurgical Center in Beaumont Hospital, examining the use of bevacizumab in an homogenous Irish glioblastoma population. We demonstrated the importance of tumour location, MGMT (O6-methylguanine- methyl-transferase gene) methylation, IDH (Isocitrate Dehydrogenase) and extent of resection (EOR) as prognostic factors in the setting of recurrent glioblastoma. Our findings also supported the hypothesis that bevacizumab should not be withheld in elderly patients of good performance status. However, no phase III trials have demonstrated an overall survival benefit primary or recurrent glioblastoma setting, treated with bevacizumab. Current evidence suggests that glioblastoma cells are able to circumvent anti-angiogenic therapy, such as bevacizumab (Bev) and develop resistance to targeted monotherapy via activation of complex molecular escape pathways such as PI3K/mTOR pathway, thereby leading to a paradoxical increase in tumour cell invasion. As a result, it is important to assess bevacizumab based combination treatment strategies in order to improve therapeutic outcomes and enhance our molecular understanding of tumour dynamics. Implementing advanced clinical neuro-imaging techniques (MRI, PET) we mechanistically interrogated the anatomical, physiological, biochemical and vascular properties of glioblastoma in response to a novel drug treatment strategy, in a reproducible orthotopic model. Our working hypothesis was that the combination of a novel dual PI3K/mTOR inhibitor (BEZ235) and bevacizuamb would convey potent anti-tumour effects in comparison to monotherapy strategies. Treatment with bevacizumab resulted in a pronounced decrease in tumour volume (T2-weighted MRI). No further reduction on tumour volume was observed with the BEV/BEZ235 combination compared with BEV monotherapy. The proliferation index markers (Ki67 & [18F]FLT) supported the observations. Using ΔR2* and ΔR2 values, the bevacizuamb/BEZ235 combination significantly reduced tumour blood volume and tumour microvessel volume in comparison to bevacizuamb alone. Microvessel density index was further reduced in animals treated with the combination, supported by von Willebrand factor (vWF) immunohistochemistry. [18F]FET uptake was reduced following treatment with bevacizumab alone, but the addition of BEZ235 in the combination group did not further reduced [18F]FET uptake. vWF immunohistochemistry demonstrated that the mean tumour vessel size was increased in all groups. Conclusion: Advanced translational neuroimaging techniques provided information on mechanism of action of the drug combination and its potential clinical responses. We have demonstrated that treatment with a BEV/BEZ235 combination could reduce peritumoral oedema reducing the requirement for corticosteroids. Translational studies, similar to this, may help to predict more accurately the clinical potential of the bevacizuamb/BEZ235 combination regimen as a novel therapeutic approach in neuro-oncology.</p

The centrally restricted diffusion sign on MRI for assessment of radiation necrosis in metastases treated with stereotactic radiosurgery

PURPOSE Differentiation of radiation necrosis from tumor progression in brain metastases treated with stereotactic radiosurgery (SRS) is challenging. For this, we assessed the performance of the centrally restricted diffusion sign. METHODS Patients with brain metastases treated with SRS who underwent a subsequent intervention (biopsy/resection) for a ring-enhancing lesion on preoperative MRI between 2000 and 2020 were included. Excluded were lesions containing increased susceptibility limiting assessment of DWI. Two neuroradiologists classified the location of the diffusion restriction with respect to the post-contrast T1 images as centrally within the ring-enhancement (the centrally restricted diffusion sign), peripherally correlating to the rim of contrast enhancement, both locations, or none. Measures of diagnostic accuracy and 95% CI were calculated for the centrally restricted diffusion sign. Cohen's kappa was calculated to identify the interobserver agreement. RESULTS Fifty-nine patients (36 female; mean age 59, range 40 to 80) were included, 36 with tumor progression and 23 with radiation necrosis based on histopathology. Primary tumors included 34 lung, 12 breast, 5 melanoma, 3 colorectal, 2 esophagus, 1 head and neck, 1 endometrium, and 1 thyroid. The centrally restricted diffusion sign was seen in 19/23 radiation necrosis cases (sensitivity 83% (95% CI 63 to 93%), specificity 64% (95% CI 48 to 78%), PPV 59% (95% CI 42 to 74%), NPV 85% (95% CI 68 to 94%)) and 13/36 tumor progression cases (difference p < 0.001). Interobserver agreement was substantial, at 0.61 (95% CI 0.45 to 70.8). CONCLUSION We found a low probability of radiation necrosis in the absence of the centrally restricted diffusion sign

Effect of low-amplitude two-dimensional radial strain at left ventricular pacing sites on response to cardiac resynchronization therapy

Background: Left ventricular (LV) lead placement to areas of scar has detrimental effects on response to cardiac resynchronization therapy (CRT). Speckle-tracking radial two-dimensional strain offers assessment of the extent of regional myocardial deformation. The aim of this study was to assess the impact of LV lead placement at areas of low-amplitude strain on CRT response. Methods: The optimal cutoff of radial strain amplitude at the LV pacing site associated with an unfavorable CRT response was determined in a derivation group (n = 65) and then tested in a second consecutive validation group (n = 75) of patients with heart failure. Patients had concordant LV leads if placed at the most delayed site, and dyssynchrony was defined as anteroseptal to posterior delay &#8805; 130 msec. CRT response was defined as a &#8805;15% reduction in LV end-systolic volume at 6 months. Results: In the derivation group, a derived cutoff for radial strain amplitude of &lt;9.8% defined low-amplitude segments (LAS) and had a high specificity but low sensitivity for predicting LV reverse remodeling, suggesting a strong negative predictive value. In the validation group, compared with patients without LAS at the LV pacing site, in patients with LAS (n = 16), CRT response was significantly lower (62.7% vs 31.3%, P &lt; .05). By multivariate analysis, LV lead concordance and the absence of an LAS at the LV pacing site but not dyssynchrony were significantly related to CRT response. Conclusion: LV lead placement over segments with two-dimensional radial strain amplitudes &lt;9.8% is associated with poor outcomes of CRT