Globally, forests are impacted by atmospheric nitrogen (N) deposition, affecting their structure and functioning above and below ground. All trees form mutualistic root symbioses with mycorrhizal ...fungi. Of the two kinds of mycorrhizal symbioses of trees, the ectomycorrhizal (EcM) symbiosis is much more sensitive to N enrichment than the arbuscular mycorrhizal (AM) symbiosis. Due to increasing N deposition, significant declines in the richness and abundance of EcM fungal species and shifts in community composition and functional traits have been recorded. Under increasing N deposition, ectomycorrhizal forests usually show enhanced foliar mass fractions of N, reduced foliar mass fractions of phosphorus (P), and, consequently, an increasing imbalance in the foliar N:P stoichiometry, ultimately impacting tree performance. The question has been raised of whether, under conditions of high N deposition, EcM trees can select EcM fungi that are both tolerant to high N availability and efficient in the acquisition of P, which could to some extent mitigate the negative impact of N deposition on nutrient balances. Here we evaluate the literature for mechanisms through which certain EcM fungi could increase P acquisition under increased N loading. We find very little evidence that under N enrichment, EcM fungi that have on average higher P efficiency might be selected and thereby prevent or delay tree N:P imbalances. However, methodological issues in some of these studies make it imperative to treat this conclusion with caution. Considering the importance of avoiding tree N:P disbalances under N enrichment and the need to restore EcM forests that have suffered from long-term excess N loading, further research into this question is urgently required.
Summary
The resilience of forests is compromised by human‐induced environmental influences pushing them towards tipping points and resulting in major shifts in ecosystem state that might be difficult ...to reverse, are difficult to predict and manage, and can have vast ecological, economic and social consequences. The literature on tipping points has grown rapidly, but almost exclusively based on aquatic and aboveground systems. So far little effort has been made to make links to soil systems, where change is not as drastically apparent, timescales may differ and recovery may be slower. Predicting belowground ecosystem state transitions and recovery, and their impacts on aboveground systems, remains a major scientific, practical and policy challenge. Recently observed major changes in aboveground tree condition across European forests are probably causally linked to ectomycorrhizal (EM) fungal changes belowground. Based on recent breakthroughs in data collection and analysis, we apply tipping point theory to forests, including their belowground component, focusing on EM fungi; link environmental thresholds for EM fungi with nutrient imbalances in forest trees; explore the role of phenotypic plasticity in EM fungal adaptation to, and recovery from, environmental change; and propose major positive feedback mechanisms to understand, address and predict forest ecosystem tipping points.
Abstract Background Previous reviews have shown that β-blocker use for the treatment of hypertension without compelling indications was associated with increased risk of stroke in the elderly. It ...remains unclear whether this increased risk was driven by the type of β-blocker. We sought to compare the efficacy of atenolol vs nonatenolol β-blockers in clinical trials enrolling young (< 60 years) and older patients with hypertension. Methods The Cochrane and MEDLINE databases were searched (January 2006-May 2013) for randomized trials evaluating stroke, myocardial infarction, death, or composite cardiovascular end points. Twenty-one hypertension trials with data on 145,811 participants were identified: 15 used atenolol, 7 were placebo-controlled trials, and 14 were active comparator trials. There were no trials of newer generation β-blockers identified. Results Among the elderly, atenolol was associated with an increased risk of stroke (relative risk RR, 1.17; 95% confidence interval CI, 1.05-1.30) compared with other antihypertensive agents. The risk of stroke for nonatenolol β-blockers compared with other agents (RR, 1.22; 95% CI, 0.99-1.50) did not reach statistical significance in the elderly. In the young, atenolol was associated with reduced risk of stroke compared with other agents (RR, 0.78; 95% CI, 0.64-0.95), whereas nonatenolol β-blockers were associated with a lower risk of composite cardiac events (RR, 0.86; 95% CI, 0.75-0.996) compared with placebo, with no significant difference in events compared with active controls. Conclusions In the young, both atenolol and nonatenolol β-blockers are effective in reducing cardiovascular end points for hypertension without compelling indications. Atenolol is associated with increased stroke in the elderly but whether this extends to nonatenolol β-blockers remains uncertain.
We present Hypertension Canada’s inaugural evidence-based recommendations for the diagnosis and management of resistant hypertension. Hypertension is present in 21% of the Canadian population, and ...among those with hypertension, resistant hypertension has an estimated prevalence from 10% to 30%. This subgroup of hypertensive individuals is important, because resistant hypertension portends a high cardiovascular risk. Because of its importance, Hypertension Canada formed a Guidelines Committee to conduct a review of the evidence and develop recommendations for the diagnosis and management of resistant hypertension. The Hypertension Canada Guidelines Committee recommends that patients with blood pressure above target, despite use of 3 or more blood pressure-lowering drugs at optimal doses, preferably including a diuretic, be identified as those with apparent resistant hypertension. Patients identified with apparent resistant hypertension should be assessed for white coat effect, nonadherence, and therapeutic inertia, investigated for secondary hypertension, and referred to a provider with expertise in hypertension. There is no randomized controlled trial evidence for better cardiovascular outcomes with any class of antihypertensive agent at this time, so recommendations for a preferred drug class cannot be made. Furthermore, we provide a summary of the current evidence concerning the role of device therapy in the management of resistant hypertension. We will continue updating the guidelines as additional high-quality evidence with relevance to daily practice becomes available.
Nous présentons ici les premières recommandations d'Hypertension Canada, basées sur des données probantes, pour le diagnostic et la prise en charge de l'hypertension résistante. L'hypertension est présente dans 21 % de la population canadienne, et parmi les personnes souffrant d'hypertension, l'hypertension résistante a une prévalence estimée entre 10 % et 30 %. Ce sous-groupe d’individus hypertendus est important, car l'hypertension résistante laisse présager un risque cardiovasculaire élevé. Compte tenu de son importance, Hypertension Canada a formé un comité des lignes directrices pour effectuer un examen des données probantes disponibles et élaborer des recommandations pour le diagnostic et la prise en charge de l'hypertension résistante. Le comité des lignes directrices d'Hypertension Canada recommande que les patients dont la pression artérielle est supérieure à la valeur cible, malgré l'administration d'au moins trois médicaments hypotenseurs à des doses optimales, incluant de préférence un diurétique, soient identifiés comme souffrant d'hypertension résistante apparente. Les patients identifiés comme présentant une hypertension résistante apparente doivent être évalués pour l'effet blouse blanche, la non-observance, l'inertie thérapeutique, doivent faire l'objet d'une investigation pour une hypertension secondaire et être référés à un prestataire de soin spécialisé dans l'hypertension. Il n'existe pas à l'heure actuelle de données issues d'essais contrôlés randomisés ayant de meilleurs résultats cardiovasculaires avec une quelconque classe d'antihypertenseurs, de sorte qu'il n'est pas encore possible de faire des recommandations pour une classe de médicaments privilégiée. En outre, nous présentons un condensé des données actuelles concernant le rôle des thérapies par dispositifs d’assistance dans la gestion de l'hypertension résistante. Nous continuerons à mettre à jour les lignes directrices au fur et à mesure que des données probantes supplémentaires de haute qualité et pertinentes pour la pratique quotidienne seront disponibles.
Case reports suggest that deaths due to asthma can occur without airway plugging. In this study, we examined the hypothesis that obstruction of the airway lumen by an exudate containing mucus and ...cells is a key feature of fatal asthma attacks.
We quantified airway narrowing and lumenal content in 275 airways from 93 patients with fatal asthma aged 10 to 49 years (59 white subjects and 34 Polynesian subjects, including 19 children), compared with airways from control patients who died suddenly without pulmonary diseases.
The severity of lumenal occlusion ranged from 4% to 100% in these cases, but only five airways showed less than 20% occlusion. Compared with controls, patients with asthma had more lumenal occlusion (mean ± SD open lumen, 42% ± 23% vs. 93% ± 8%), greater mucus occlusion (28% ± 13% vs. 5% ± 6%), and more occlusion by cells (30% ± 17% vs. 3% ± 2%, all
P<0.0001). Airway narrowing was greater in larger airways (
P<0.0001) and older patients (
P = 0.009). Greater lumen content was associated with a higher proportion of cells (
P = 0.003), and cells made up a higher proportion of the exudate in the small airways (
P<0.0001). Lumenal mucus was greater in younger patients with asthma (
P = 0.0007) and in Polynesian patients with asthma (
P = 0.04).
Airway lumenal obstruction by an exudate composed of mucus and cells is a major contributing cause of fatal asthma in most patients.
We sought to examine the relationship between housing status and risk of HIV-infection among injection drug users in Vancouver, Canada. Using Kaplan–Meier survival analysis, we found an elevated HIV ...incidence rate among those who reported residing in unstable housing (log-rank
p
=
0.006
). In Cox's regression survival analysis, unstable housing remained marginally associated with elevated risks of HIV infection (relative hazard=1.40 (95% confidence interval: 0.09–2.00);
p
=
0.084
) after adjustment for potential confounders including syringe sharing. Adjusted generalized estimating equations analysis that examined factors associated with unstable housing demonstrated that residing in unstable housing was independently associated with several HIV risk behaviours including borrowing used needles (adjusted odds ratio (OR)=1.14) and sex-trade involvement (adjusted OR=1.19). Our findings suggest that unstable housing environments are associated with elevated risk of HIV- infection due to risk behaviours that take place in these environments. Implications for policy including more comprehensive housing interventions (e.g. ‘floating support’) are discussed.
Hypertension affects 1 in 5 Canadians and is the leading cause of morbidity and mortality globally. Hypertension control is declining due to multiple factors including lack of access to primary care. ...Consequently, patients with hypertension frequently visit the emergency department (ED) due to high blood pressure (BP). Telehealth for Emergency-Community Continuity of Care Connectivity via Home-Telemonitoring Blood Pressure is a pilot project that implements and evaluates a comprehensive home blood pressure telemonitoring (HBPT) and physician case management protocol designed as a postdischarge management strategy to support patients with asymptomatic elevated BP as they transition from the ED to home.
Our objective was to conduct a feasibility study of an HBPT program for patients with asymptomatic elevated BP discharged from the ED.
Patients discharged from an urban, tertiary care hospital ED with asymptomatic elevated BP were recruited in Vancouver, British Columbia, Canada, and provided with HBPT technology for 3 months of monitoring post discharge and referred to specialist hypertension clinics. Participants monitored their BP twice in the morning and evenings and tele-transmitted readings via Bluetooth Sensor each day using an app. A monitoring clinician received these data and monitored the patient's condition daily and adjusted antihypertensive medications. Feasibility outcomes included eligibility, recruitment, adherence to monitoring, and retention rates. Secondary outcomes included proportion of those who were defined as having hypertension post-ED visits, changes in mean BP, overall BP control, medication adherence, changes to antihypertensive medications, quality of life, and end user experience at 3 months.
A total of 46 multiethnic patients (mean age 63, SD 17 years, 69%, n=32 women) found to have severe hypertension (mean 191, SD 23/mean 100, SD 14 mm Hg) in the ED were recruited, initiated on HBPT with hypertension specialist physician referral and followed up for 3 months. Eligibility and recruitment rates were 40% (56/139) and 88% (49/56), respectively. The proportion of participants that completed ≥80% of home BP measurements at 1 and 3 months were 67% (31/46) and 41% (19/46), respectively. The proportion of individuals who achieved home systolic BP and diastolic BP control at 3 months was 71.4% (30/42) and 85.7% (36/42) respectively. Mean home systolic and diastolic BP improved by -13/-5 mm Hg after initiation of HBPT to the end of the study. Patients were prescribed 1 additional antihypertensive medication. No differences in medication adherence from enrollment to 3 months were noted. Most patients (76%, 25/33) were highly satisfied with the HBPT program and 76% (25/33) found digital health tools easy to use.
HBPT intervention is a feasible postdischarge management strategy and can be beneficial in supporting patients with asymptomatic elevated BP from the ED. A randomized trial is underway to evaluate the efficacy of this intervention on BP control.
Hypertension Canada’s 2020 guidelines for the prevention, diagnosis, risk assessment, and treatment of hypertension in adults and children provide comprehensive, evidence-based guidance for health ...care professionals and patients. Hypertension Canada develops the guidelines using rigourous methodology, carefully mitigating the risk of bias in our process. All draft recommendations undergo critical review by expert methodologists without conflict to ensure quality. Our guideline panel is diverse, including multiple health professional groups (nurses, pharmacy, academics, and physicians), and worked in concert with experts in primary care and implementation to ensure optimal usability. The 2020 guidelines include new guidance on the management of resistant hypertension and the management of hypertension in women planning pregnancy.
Les lignes directrices 2020 d’Hypertension Canada pour la prévention, le diagnostic, l'évaluation des risques et le traitement de l'hypertension chez l’adulte et l’enfant fournissent aux professionnels de la santé et aux patients des conseils complets et fondés sur des données probantes. Hypertension Canada élabore ces lignes directrices en utilisant une méthodologie rigoureuse, en atténuant soigneusement le risque de partialité dans notre processus. Tous les projets de recommandations sont soumis à une évaluation critique par des experts en méthodologie, sans partialité, afin d'en garantir la qualité. Notre panel de lignes directrices est diversifié, comprenant de multiples groupes de professionnels de la santé (soins infirmiers, pharmacie, universitaire et médecins), et a travaillé de concert avec des experts en soins primaires et d’experts en mise en œuvre pour garantir une utilisation optimale. Les lignes directrices 2020 comprennent de nouvelles orientations sur la gestion de l'hypertension résistante et la prise en charge de l'hypertension chez les femmes qui planifient une grossesse.
Hypertension Canada provides annually updated, evidence-based guidelines for the diagnosis, assessment, prevention, and treatment of hypertension in adults and children. This year, the adult and ...pediatric guidelines are combined in one document. The new 2018 pregnancy-specific hypertension guidelines are published separately. For 2018, 5 new guidelines are introduced, and 1 existing guideline on the blood pressure thresholds and targets in the setting of thrombolysis for acute ischemic stroke is revised. The use of validated wrist devices for the estimation of blood pressure in individuals with large arm circumference is now included. Guidance is provided for the follow-up measurements of blood pressure, with the use of standardized methods and electronic (oscillometric) upper arm devices in individuals with hypertension, and either ambulatory blood pressure monitoring or home blood pressure monitoring in individuals with white coat effect. We specify that all individuals with hypertension should have an assessment of global cardiovascular risk to promote health behaviours that lower blood pressure. Finally, an angiotensin receptor-neprilysin inhibitor combination should be used in place of either an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker in individuals with heart failure (with ejection fraction < 40%) who are symptomatic despite appropriate doses of guideline-directed heart failure therapies. The specific evidence and rationale underlying each of these guidelines are discussed.
Chaque année Hypertension Canada publie une mise à jour de ses lignes directrices fondées sur des données probantes relatives au diagnostic, à l'évaluation, à la prévention et au traitement de l'hypertension chez l'adulte et l'enfant. Cette année, les lignes directrices applicables aux adultes et aux enfants sont combinées en un seul document. Les nouvelles lignes directrices 2018 portant précisément sur l'hypertension pendant la grossesse sont publiées séparément. Pour 2018, cinq nouvelles lignes directrices sont présentées, et une ligne directrice existante portant sur les seuils et les cibles de pression artérielle dans le contexte de la thrombolyse dans un cas d'accident vasculaire cérébral ischémique aigu est révisée. L'utilisation de tensiomètres-bracelets validés pour l'estimation de la pression artérielle chez les personnes dont le bras a une circonférence élevée est à présent incluse. Des indications sont données pour les mesures de la pression artérielle dans le cadre d'un suivi à l'aide de méthodes normalisées et de dispositifs électroniques (oscillométriques) positionnés au niveau du bras chez les personnes hypertendues, ainsi que de la surveillance de la pression artérielle ambulatoire ou à domicile chez les personnes sujettes au « syndrome de la blouse blanche ». Nous recommandons notamment de procéder à une évaluation du risque cardiovasculaire global de toutes les personnes atteintes d'hypertension afin de les inciter à adopter de saines habitudes de vie permettant d’abaisser leur pression artérielle. Enfin, chez les personnes atteintes d'insuffisance cardiaque (présentant une fraction d'éjection < 40 %) qui sont symptomatiques malgré un traitement de cette affection à des doses appropriées et conforme aux lignes directrices, il est recommandé d'utiliser une association de médicaments inhibiteurs des récepteurs de l'angiotensine et de la néprilysine au lieu d’un inhibiteur de l’enzyme de conversion de l'angiotensine ou d'un antagoniste des récepteurs de l'angiotensine en monothérapie. Les données probantes et la justification qui sous-tendent chacune de ces lignes directrices sont analysées.
There have been growing concerns about possible gender-related differences in rates of responses to highly active antiretroviral therapy (HAART). We therefore examined the association between gender ...and time to HIV-1 RNA rebound in antiretroviral-naive HIV-infected patients initiating HAART in a population-based setting.
We evaluated all antiretroviral-naive HIV-infected men and women who achieved HIV-1 RNA suppression at least once (HIV RNA <500 copies/mL) after initiating HAART between August 1, 1996 and July 31, 2000 and who were followed until March 31, 2002 in a province-wide HIV treatment program. We evaluated time to HIV-1 RNA rebound (> or =500 copies/mL) using Kaplan-Meier methods and Cox proportional hazards regression.
In total, 844 (87.0%) men and 126 (13.0%) women initiated HAART during the study period and achieved HIV-1 RNA suppression at least once. Overall rates of rebound were 47.4% and 34.0% for women and men, respectively (log-rank, P < 0.021). Women were less likely to be > or =95% adherent (P = 0.001) and more likely to have a history of injection drug use (P = 0.001). In multivariate analysis, incomplete adherence was found to be highly predictive of HIV-1 RNA rebound (adjusted relative hazard ARH = 4.00, 95% confidence interval CI: 3.33-5.00). Although female patients had higher rates of HIV-1 RNA rebound in univariate analysis (relative hazard RH = 1.39, 95% CI: 1.05-1.82), this was no longer statistically significant once other known confounders such as adherence and injection drug use were adjusted for (RH = 0.95, 95% CI: 0.71-1.28). When the analyses were stratified based on history of injection drug use, we found that rates of rebound were higher among injection drug-using women than among injection drug-using men (P = 0.048), whereas there was no gender difference among non-injection drug users with respect to rebound (P = 0.345).
We found that higher rates of HIV-1 RNA rebound among women were primarily explained by incomplete adherence, which was more prevalent among women in this cohort. Our findings suggest that psychosocial factors such as drug use and incomplete adherence predict HIV-1 RNA rebound and that gender differences in time to rebound can be largely attributed to a disproportionate prevalence of these factors among women in this population.
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