Novel weapons: Invasive plant suppresses fungal mutualists in America but not in its native Europe

Why some invasive plant species transmogrify from weak competitors at home to strong competitors abroad remains one of the most elusive questions in ecology. Some evidence suggests that disproportionately high densities of some invaders are due to the release of biochemicals that are novel, and therefore harmful, to naive organisms in their new range. So far, such evidence has been restricted to the direct phytotoxic effects of plants on other plants. Here we found that one of North America's most aggressive invaders of undisturbed forest understories, Alliaria petiolata (garlic mustard) and a plant that inhibits mycorrhizal fungal mutualists of North American native plants, has far stronger inhibitory effects on mycorrhizas in invaded North American soils than on mycorrhizas in European soils where A. petiolata is native. This antifungal effect appears to be due to specific flavonoid fractions in A. petiolata extracts. Furthermore, we found that suppression of North American mycorrhizal fungi by A. petiolata corresponds with severe inhibition of North American plant species that rely on these fungi, whereas congeneric European plants are weakly affected. These results indicate that phytochemicals, benign to resistant mycorrhizal symbionts in the home range, may be lethal to naive native mutualists in the introduced range and indirectly suppress the plants that rely on them.

The relative importance of immediate allelopathy and allelopathic legacy in invasive plant species

Abstract Some introduced invasive species may be competitively superior to natives because they release allelochemicals, which negatively affect native species. Allelochemicals can be immediately effective after being released but can also persist in soils, resulting in a legacy effect. However, to our knowledge there are no studies which distinguish between allelopathic legacy and immediate allelopathy of invasive species and also test for their relative importance and possible interdependence. We used eleven invasive species and tested whether they show immediate allelopathy and allelopathic legacy effects in a factorial pairwise competition experiment using field-collected soil (invaded/non-invaded) and activated carbon to neutralize allelochemicals. We grew two native and the invasive species in both monocultures and pairwise mixtures. In monocultures, the native species did not experience an allelopathic legacy effect of the invasives, suggesting that invaders generally lack persistent allelochemicals. However, the effects of invader allelochemicals were modulated by competitive interactions. In competition, immediate allelopathy decreased competitive ability of natives, while allelopathic legacy positively affected the natives. Moreover, immediate allelopathic and allelopathic legacy effects were strongly negatively correlated. Our results suggest that both immediately released allelochemicals and the allelochemical legacy of invasive species are important for plant performance under natural conditions, and that natives should be able to recover once the invaders are removed. To test whether immediate allelopathy is responsible for plant invasion success, further studies should compare allelopathic effects between invasive and closely related native species.

Invasive plant species do not create more negative soil conditions for other plants than natives

Abstract A major task in ecology is to establish the degree of generality of ecological mechanisms. Here we present results from a multi-species experiment that tested whether a set of invasive species altered the soil conditions to the detriment of other species by releasing allelopathic compounds or inducing shifts in soil biota composition, and whether this effect was more pronounced relative to a set of closely related native species. We pre-cultivated soil with 23 exotic invasive, 19 related native and 6 related exotic garden species and used plain soil as a control. To separate allelopathy from effects on the soil biota, we sterilized half of the soil. Then, we compared the effect of soil pre-cultivation and sterilization on germination and growth of four native test species in two experiments. The general effect of soil sterilization was positive. The effect of soil pre-cultivation on test species performance was neutral to positive, and sterilization reduced this positive effect. This indicates general absence of allelopathic compounds and a shift toward a less antagonistic soil biota by cultivation species. In both experiments, pre-cultivation effects did not differ systematically between exotic invasive, exotic garden or native species. Our results do not support the hypothesis that invasive plants generally inhibit the growth of others by releasing allelopathic compounds or accumulating a detrimental soil biota.

EACTS expert consensus statement for surgical management of pleural empyema

Pleural infection is a frequent clinical condition. Prompt treatment has been shown to reduce hospital costs, morbidity and mortality. Recent advances in treatment have been variably implemented in clinical practice. This statement reviews the latest developments and concepts to improve clinical management and stimulate further research. The European Association for Cardio-Thoracic Surgery (EACTS) Thoracic Domain and the EACTS Pleural Diseases Working Group established a team of thoracic surgeons to produce a comprehensive review of available scientific evidence with the aim to cover all aspects of surgical practice related to its treatment, in particular focusing on: surgical treatment of empyema in adults; surgical treatment of empyema in children; and surgical treatment of post-pneumonectomy empyema (PPE). In the management of Stage 1 empyema, prompt pleural space chest tube drainage is required. In patients with Stage 2 or 3 empyema who are fit enough to undergo an operative procedure, there is a demonstrated benefit of surgical debridement or decortication [possibly by video-assisted thoracoscopic surgery (VATS)] over tube thoracostomy alone in terms of treatment success and reduction in hospital stay. In children, a primary operative approach is an effective management strategy, associated with a lower mortality rate and a reduction of tube thoracostomy duration, length of antibiotic therapy, reintervention rate and hospital stay. Intrapleural fibrinolytic therapy is a reasonable alternative to primary operative management. Uncomplicated PPE [without bronchopleural fistula (BPF)] can be effectively managed with minimally invasive techniques, including fenestration, pleural space irrigation and VATS debridement. PPE associated with BPF can be effectively managed with individualized open surgical techniques, including direct repair, myoplastic and thoracoplastic techniques. Intrathoracic vacuum-assisted closure may be considered as an adjunct to the standard treatment. The current literature cements the role of VATS in the management of pleural empyema, even if the choice of surgical approach relies on the individual surgeon's preference.

Transcatheter aortic valve implantation: prevention and management of complications

Assessment of elderly patients with severe aortic stenosis and decisions in terms of management strategy (conservative with or without balloon aortic valvuloplasty, transcatheter aortic valve implantation (TAVI) or surgical aortic valve replacement) are complex and warrant a multidisciplinary approach involving collaboration between experienced cardiac surgeons, interventional cardiologists, cardiac imaging specialists, anaesthesiologists, geriatricians and a specialised nursing staff. Patient history, comorbid conditions, perioperative risk stratification as well as anatomical and procedural considerations require careful review on an individual, case-by-case basis and have a major impact on treatment allocation. The aims of this article are to provide insights into the fundamental role of appropriate patient screening and selection, and to review the nature, management and prevention of the most important procedural complications associated with the TAVI procedure.

The cobblers stick to their lasts: pollinators prefer native over alien plant species in a multi-species experiment

The majority of plant species rely, at least partly, on animals for pollination. Our knowledge on whether pollinator visitation differs between native and alien plant species, and between invasive and non-invasive alien species is still limited. Additionally, because numerous invasive plant species are escapees from horticulture, the transition from human-assisted occurrence in urbanized habitats to unassisted persistence and spread in (semi-)natural habitats requires study. To address whether pollinator visitation differs between native, invasive alien and non-invasive alien species, we did pollinator observations for a total of 17 plant species representing five plant families. To test whether pollinator visitation to the three groups of species during the initial stage of invasion depends on habitat type, we did the study in three urbanized habitats and three semi-natural grasslands, using single potted plants. Native plants had more but smaller flower units than alien plants, and invasive alien plants had more but smaller flowers than non-invasive alien plants. After accounting for these differences in floral display, pollinator visitation was higher for native than for alien plant species, but did not differ between invasive and non-invasive alien plant species. Pollinator visitation was on average higher in semi-natural than in urbanized habitats, irrespective of origin or status of the plant species. This might suggest that once an alien species has managed to escape from urbanized into more natural habitats, pollinator limitation will not be a major barrier to establishment and invasion.

Allelopathic effects of three plant invaders on germination of native species: a field study

The ability of some invasive plant species to produce biochemical compounds toxic to native species, called allelopathy, is thought to be one of the reasons for their success when introduced to a novel range, an idea known as the Novel Weapons Hypothesis. However, support for this hypothesis mainly comes from bioassays and experiments conducted under controlled environments, whereas field evidence is rare. In a field experiment, we investigated whether three plant species invasive in Europe, Solidago gigantea, Impatiens glandulifera and Erigeron annuus, inhibit the germination of native species through allelopathy more than an adjacent native plant community. At three sites for each invasive species, we compared the germination of native species that were sown on invaded and non-invaded plots. Half of these plots were amended with activated carbon to reduce the influence of potential allelopathic compounds. The germination of sown seeds and of seeds from the seedbank was monitored over a period of 9 weeks. Activated carbon generally enhanced seed germination. This effect was equally pronounced in invaded and adjacent non-invaded plots, indicating that invasive species do not suppress germination more than a native plant community. In addition, more seeds germinated from the seedbank on invaded than on non-invaded soil, probably due to previous suppression of germination by the invasive species. Our field study does not provide evidence for the Novel Weapons Hypothesis with respect to the germination success of natives. Instead, our results suggest that if invasive species release allelopathic compounds that suppress germination, they do so to a similar degree as the native plant community.

Home-based versus clinic-based specimen collection in the management of Chlamydia trachomatis and Neisseria gonorrhoeae infections

BACKGROUND Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are the most frequent causes of bacterial sexually transmitted infections (STIs). Management strategies that reduce losses in the clinical pathway from infection to cure might improve STI control and reduce complications resulting from lack of, or inadequate, treatment. OBJECTIVES To assess the effectiveness and safety of home-based specimen collection as part of the management strategy for Chlamydia trachomatis and Neisseria gonorrhoeae infections compared with clinic-based specimen collection in sexually-active people. SEARCH METHODS We searched the Cochrane Sexually Transmitted Infections Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and LILACS on 27 May 2015, together with the World Health Organization International Clinical Trials Registry (ICTRP) and ClinicalTrials.gov. We also handsearched conference proceedings, contacted trial authors and reviewed the reference lists of retrieved studies. SELECTION CRITERIA Randomized controlled trials (RCTs) of home-based compared with clinic-based specimen collection in the management of C. trachomatis and N. gonorrhoeae infections. DATA COLLECTION AND ANALYSIS Three review authors independently assessed trials for inclusion, extracted data and assessed risk of bias. We contacted study authors for additional information. We resolved any disagreements through consensus. We used standard methodological procedures recommended by Cochrane. The primary outcome was index case management, defined as the number of participants tested, diagnosed and treated, if test positive. MAIN RESULTS Ten trials involving 10,479 participants were included. There was inconclusive evidence of an effect on the proportion of participants with index case management (defined as individuals tested, diagnosed and treated for CT or NG, or both) in the group with home-based (45/778, 5.8%) compared with clinic-based (51/788, 6.5%) specimen collection (risk ratio (RR) 0.88, 95% confidence interval (CI) 0.60 to 1.29; 3 trials, I² = 0%, 1566 participants, moderate quality). Harms of home-based specimen collection were not evaluated in any trial. All 10 trials compared the proportions of individuals tested. The results for the proportion of participants completing testing had high heterogeneity (I² = 100%) and were not pooled. We could not combine data from individual studies looking at the number of participants tested because the proportions varied widely across the studies, ranging from 30% to 96% in home group and 6% to 97% in clinic group (low-quality evidence). The number of participants with positive test was lower in the home-based specimen collection group (240/2074, 11.6%) compared with the clinic-based group (179/967, 18.5%) (RR 0.72, 95% CI 0.61 to 0.86; 9 trials, I² = 0%, 3041 participants, moderate quality). AUTHORS' CONCLUSIONS Home-based specimen collection could result in similar levels of index case management for CT or NG infection when compared with clinic-based specimen collection. Increases in the proportion of individuals tested as a result of home-based, compared with clinic-based, specimen collection are offset by a lower proportion of positive results. The harms of home-based specimen collection compared with clinic-based specimen collection have not been evaluated. Future RCTs to assess the effectiveness of home-based specimen collection should be designed to measure biological outcomes of STI case management, such as proportion of participants with negative tests for the relevant STI at follow-up.

Outcomes of Active Surveillance for Ductal Carcinoma in Situ: A Computational Risk Analysis.

BACKGROUND Ductal carcinoma in situ (DCIS) is a noninvasive breast lesion with uncertain risk for invasive progression. Usual care (UC) for DCIS consists of treatment upon diagnosis, thus potentially overtreating patients with low propensity for progression. One strategy to reduce overtreatment is active surveillance (AS), whereby DCIS is treated only upon detection of invasive disease. Our goal was to perform a quantitative evaluation of outcomes following an AS strategy for DCIS. METHODS Age-stratified, 10-year disease-specific cumulative mortality (DSCM) for AS was calculated using a computational risk projection model based upon published estimates for natural history parameters, and Surveillance, Epidemiology, and End Results data for outcomes. AS projections were compared with the DSCM for patients who received UC. To quantify the propagation of parameter uncertainty, a 95% projection range (PR) was computed, and sensitivity analyses were performed. RESULTS Under the assumption that AS cannot outperform UC, the projected median differences in 10-year DSCM between AS and UC when diagnosed at ages 40, 55, and 70 years were 2.6% (PR = 1.4%-5.1%), 1.5% (PR = 0.5%-3.5%), and 0.6% (PR = 0.0%-2.4), respectively. Corresponding median numbers of patients needed to treat to avert one breast cancer death were 38.3 (PR = 19.7-69.9), 67.3 (PR = 28.7-211.4), and 157.2 (PR = 41.1-3872.8), respectively. Sensitivity analyses showed that the parameter with greatest impact on DSCM was the probability of understaging invasive cancer at diagnosis. CONCLUSION AS could be a viable management strategy for carefully selected DCIS patients, particularly among older age groups and those with substantial competing mortality risks. The effectiveness of AS could be markedly improved by reducing the rate of understaging.