Publications by authors named "John Boyd"

Introduction: Survivors of critical illness and their caregivers are at risk for long-term cognitive, physical and psychiatric impairments known as post-intensive care syndrome (PICS) and PICS-family, respectively. This study will assess the feasibility of a randomised controlled trial (RCT) evaluating an intensive care unit (ICU) follow-up care bundle versus standard-of-care for ICU patients and their caregivers.

Methods And Analysis: This is a single-centre feasibility study.

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  • The study investigates differences in thrombo-inflammatory responses and outcomes between non-COVID-19 community-acquired pneumonia (CAP) and COVID-19 CAP in hospitalized adults in Canada.
  • Non-COVID-19 CAP patients displayed lower 28-day mortality rates and fewer complications compared to those with COVID-19, indicating a more effective immune response developed over time against bacterial infections.
  • The findings suggest that the complexities of the immune response to COVID-19 resulted in higher mortality rates, highlighting the challenges posed by emerging viruses compared to known pathogens.
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Background: Most Canadians receive their care in community hospitals, yet most clinical research is conducted in academic hospitals. This study aims to compare patients with community acquired pneumonia (CAP) treated in academic and community hospitals with respect to their demographics, clinical characteristics, treatments and outcomes.

Methods: This nested observational cohort substudy of the Community Acquired Pneumonia: Toward InnoVAtive Treatment (CAPTIVATE) trial included 1,329 hospitalized adults with CAP recruited between March 1st, 2018 and September 31st, 2023 from 15 Canadian hospitals.

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  • Researchers investigated the effect of losartan, an angiotensin receptor blocker, on 28-day mortality in hospitalized COVID-19 patients compared to usual care, due to its potential impact on angiotensin levels.
  • The study was stopped early due to safety concerns, showing that adverse events and hypotension were significantly higher in the losartan group (39.8% SAEs and 30.4% hypotension) versus the control group (27.2% SAEs and 15.3% hypotension).
  • There was no significant difference in 28-day mortality (6.5% for losartan vs. 5.9% for usual care), indicating that ARBs should be used cautiously in this patient population to
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  • * A pilot randomized trial will involve 90 donors and 324 organ recipients across nine hospitals in Ontario and Québec, with participants receiving either tacrolimus or a placebo before organ retrieval.
  • * Researchers will assess the trial's feasibility, including donor enrollment and recipient consent, while monitoring graft function and survival; findings will be shared publicly through publications and conferences.
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  • Sepsis is a serious condition that can cause death, and pneumonia is a major cause of it.
  • Low levels of a type of cholesterol called HDL-C can increase the risk of dying from sepsis, but a drug called anacetrapib that blocks CETP can help raise HDL-C levels and lower the death rate in mice with sepsis.
  • The study suggests that blocking CETP not only helps the immune system fight off bacteria better but also reduces inflammation, which can be harmful during sepsis.
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  • ARDS (Acute Respiratory Distress Syndrome) is a critical condition linked mainly to infections like COVID-19, influenza, and bacterial pneumonia, and research is focused on its mechanisms and treatment options.
  • The study aims to compare metabolic profiles of ARDS caused by COVID-19, H1N1 influenza, and bacterial pneumonia to understand their unique metabolic pathways.
  • Results showed distinct metabolic differences based on the infection type, indicating different underlying mechanisms in ARDS associated with each infectious cause.
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Background: Critically ill patients are at high risk of acquiring ventilator-associated pneumonia (VAP), which occurs in approximately 20% of mechanically ventilated patients. VAP results either from aspiration of pathogen-contaminated oropharyngeal secretions or contaminated biofilms that form on endotracheal tubes (ETTs) after intubation. VAP results in increased duration of mechanical ventilation, increased intensive care unit and hospital length of stay, increased risk of death and increased healthcare costs.

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  • * Researchers analyzed protein levels in 74 patients at three different time points after diagnosis, using a method called multiple reaction monitoring on 269 peptides, alongside routine lung function tests.
  • * The study found increases in proteins linked to lipid-related pathways over time, while those related to immune responses decreased; it also noted significant differences in protein concentrations between males and females affecting lung function.
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Background: The COVID-19 pandemic could impact frequency and mortality of non-COVID-19 community-acquired pneumonia (CAP). Changes in frequency, patient mix, treatment and organ dysfunction could cascade together to increase mortality of CAP during compared with pre-COVID-19.

Methods: Hospitalised CAP patients at St.

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Background: Omicron is the current predominant variant of concern of SARS-CoV-2. We hypothesized that vaccination alters outcomes of patients hospitalized with COVID-19 during the Omicron wave and that these patients have different characteristics and outcomes than in previous waves.

Methods: This is a substudy of the Host Response Mediators in Coronavirus (COVID-19) Infection (ARBs CORONA I) trial, which included adults admitted to hospital with acute COVID-19 up to July 2022 from 9 hospitals in British Columbia, Ontario and Quebec.

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Background: A significant portion of cryptogenic stroke is hypothesized to be secondary to cardiac embolism. However, transthoracic echocardiogram is usually delayed after stroke, and more detailed cardiac imaging is not routinely done.

Aims: This study aimed to determine whether non-ECG-gated cardiac CT angiography (cCTA) during hyperacute stroke would provide diagnostic quality images and act as an adjunct modality of cardiac imaging to detect sources of emboli.

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Introduction: In donation after circulatory determination of death, death is declared 5 min after circulatory arrest. This practice assumes, but does not explicitly confirm, permanent loss of brain activity. While this assumption is rooted a strong physiological rationale, paucity of direct human data regarding temporal relationship between cessation of brain activity and circulatory arrest during the dying process threatens public and healthcare provider trust in deceased organ donation.

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Introduction: Traumatic brain injury (TBI) is the leading cause of mortality and long-term disability in young adults. Despite the high prevalence of anaemia and red blood cell transfusion in patients with TBI, the optimal haemoglobin (Hb) transfusion threshold is unknown. We undertook a randomised trial to evaluate whether a liberal transfusion strategy improves clinical outcomes compared with a restrictive strategy.

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Background And Aims: Endotoxins carried within LDL are cleared from the circulation via hepatic LDL receptor (LDLR)-mediated endocytosis. Proprotein convertase subtilisin-kexin type 9 (PCSK9) reduces this clearance by down-regulating LDLR density on hepatocytes. In addition to hepatocytes, vascular endothelial cells also express receptor targets of PCSK9, including LDLR.

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Introduction/aims: Most mouse models of muscular dystrophy (MD) show mild phenotypes, which limits the translatability of experimental therapies to patients. A growing body of evidence suggests that MD is accompanied by metabolic abnormalities that could potentially exacerbate the primary muscle wasting process. Since thermoneutral (TN) housing of mice (~30°C) has been shown to affect many metabolic parameters, particularly when combined with a Western diet (WD), our aim was to determine whether the combination of TN and WD exacerbates muscle wasting in dysferlin-deficient BLAJ mice, a common model of limb-girdle MD type 2b (LGMD2b).

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  • The study aimed to assess if angiotensin receptor blockers (ARBs) or ACE inhibitors improve outcomes for hospitalized COVID-19 patients based on sex, while also investigating sex-related differences in the renin-angiotensin system (RAS).
  • The research involved a prospective cohort study of 1,686 hospitalized patients across 10 Canadian urban hospitals, measuring baseline characteristics and clinical outcomes related to ARB/ACE inhibitor use.
  • Findings revealed that males on ARBs showed reduced need for ventilation and vasopressors compared to those who weren’t on these medications, while no significant benefits were found for females, highlighting a notable sex difference in treatment response.
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Background: There have been multiple waves in the COVID-19 pandemic in many countries. We sought to compare mortality and respiratory, cardiovascular and renal dysfunction between waves in 3 Canadian provinces.

Methods: We conducted a substudy of the ARBs CORONA I study, a multicentre Canadian pragmatic observational cohort study that examined the association of pre-existing use of angiotensin receptor blockers with outcomes in adults admitted to hospital with acute COVID-19 up to April 2021 from 9 community and teaching hospitals in 3 Canadian provinces (British Columbia, Ontario and Quebec).

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The host response to COVID-19 pathophysiology over the first few days of infection remains largely unclear, especially the mechanisms in the blood compartment. We report on a longitudinal proteomic analysis of acute-phase COVID-19 patients, for which we used blood plasma, multiple reaction monitoring with internal standards, and data-independent acquisition. We measured samples on admission for 49 patients, of which 21 had additional samples on days 2, 4, 7, and 14 after admission.

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Introduction: Initiation of acute kidney replacement therapy (KRT) is common in critically ill adults admitted to the intensive care unit (ICU), and associated with increased morbidity and mortality. KRT has been linked to poor neurocognitive outcomes, leading to reduced quality of life and increased utilisation of healthcare resources. Adults on dialysis in the ICU may be particularly at risk of neurocognitive impairment, as survivors of critical illness are already predisposed to developing cerebrovascular disease and cognitive dysfunction long-term relative to healthy controls.

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Background: Patients on hemodialysis (HD) are known to exhibit low values of regional cerebral oxygenation (rSO2) and impaired cognitive functioning. The etiology of both is currently unknown.

Objective: To determine the feasibility of serially monitoring rSO2 in patients initiating HD.

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Objectives: Severe acute respiratory syndrome-related coronavirus-2 binds and inhibits angiotensin-converting enzyme-2. The frequency of acute cardiac injury in patients with coronavirus disease 2019 is unknown. The objective was to compare the rates of cardiac injury by angiotensin-converting enzyme-2-binding viruses from viruses that do not bind to angiotensin-converting enzyme-2.

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