Publications by authors named "Alexander David"

In this study, we explore the work of breathing (WoB) experienced by aviators during the Anti-G Straining Maneuver (AGSM) to improve pilot safety and performance. Traditional airflow models of WoB fail to adequately distinguish between breathing rate and inspiratory frequency, leading to potentially inaccurate assessments. This mismatch can have serious implications, particularly in critical flight situations where understanding the true respiratory workload is essential for maintaining performance.

View Article and Find Full Text PDF

is an underdiagnosed and underreported etiology of pneumonia. serogroup 1 (LpSG1) is thought to be the most common pathogenic subgroup. This assumption is based on the frequent use of a urinary antigen test (UAT), only capable of diagnosing LpSG1.

View Article and Find Full Text PDF

In December 2018, an outbreak of Enteritidis infections was identified in Canada by whole-genome sequencing (WGS). An investigation was initiated to identify the source of the illnesses, which proved challenging and complex. Microbiological hypothesis generation methods included comparisons of isolate sequence data to historical domestic outbreaks and international repositories.

View Article and Find Full Text PDF
Article Synopsis
  • - Fullerene whiskers (FLWs) and fullerenes (FLs) are rod-like structures made of carbon, and their shape raises concerns about potential health risks similar to those posed by asbestos and carbon nanotubes, but no long-term studies on their carcinogenic effects have been conducted.
  • - In a study, male rats were given FL, FLW, and different types of multi-walled carbon nanotubes (MWCNT) to assess lung and pleural carcinogenicity, leading to analyses at 1 and 104 weeks post-exposure.
  • - Results showed that while MWCNT exposure led to significant increases in lung tumors and oxidative DNA damage, FL and FLW did not induce carcinogenic effects in the
View Article and Find Full Text PDF

Syphilis, caused by subsp. (TPA), is becoming a significant public health concern, with rising incidence in Manitoba exceeding the national average. The province has also seen a demographic shift leading to women representing 51.

View Article and Find Full Text PDF

Background: Helicobacter pylori infection is prevalent worldwide and can lead to peptic ulcer disease (PUD) and gastric cancer. Effective diagnosis and treatment of H. pylori infection by gastroenterologists and family physicians is crucial.

View Article and Find Full Text PDF

Post-market surveillance of test performance is a critical function of public health agencies and clinical researchers that ensures tests maintaining diagnostic characteristics following their regulatory approval. Changes in product quality, manufacturing processes over time, or the evolution of new variants may impact product performance. During the COVID-19 pandemic, a plethora of point-of-care tests (POCTs) was released onto the Canadian market.

View Article and Find Full Text PDF

Polycyclic aromatic hydrocarbon (PAH) pollutants and microbiome products converge on the aryl hydrocarbon receptor (AhR) to redirect selective rapid adherence of isolated bone marrow (BM) cells. In young adult mice, Cyp1b1-deficiency and AhR activation by PAH, particularly when prolonged by Cyp1a1 deletion, produce matching gene stimulations in these BM cells. Vascular expression of Cyp1b1 lowers reactive oxygen species (ROS), suppressing NF-κB/RelA signaling.

View Article and Find Full Text PDF

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging is used across many fields for the atomic and molecular characterization of surfaces, with both high sensitivity and high spatial resolution. When large analysis areas are required, standard ToF-SIMS instruments allow for the acquisition of adjoining tiles, which are acquired by rastering the primary ion beam. For such large area scans, tiling artifacts are a ubiquitous challenge, manifesting as intensity gradients across each tile and/or sudden changes in intensity between tiles.

View Article and Find Full Text PDF

Macrolides are a mainstay of therapy for infections due to nontuberculous mycobacteria (NTM). Among rapidly growing mycobacteria (RGM), inducible macrolide resistance is associated with four chromosomal 23S rRNA methylase () genes. Beginning in 2018, we detected high-level inducible clarithromycin resistance (MICs of ≥16μg/mL) in clinical isolates of Mycobacterium chelonae, an RGM species not previously known to contain genes.

View Article and Find Full Text PDF

Pathogen genomics is a critical tool for public health surveillance, infection control, outbreak investigations as well as research. In order to make use of pathogen genomics data, they must be interpreted using contextual data (metadata). Contextual data include sample metadata, laboratory methods, patient demographics, clinical outcomes and epidemiological information.

View Article and Find Full Text PDF
Article Synopsis
  • - The study analyzed the molecular epidemiology of invasive meningococcal disease (IMD) in Atlantic Canada from 2014 to 2020, specifically looking at serotype and potential vaccine coverage for serogroup B (MenB).
  • - Results revealed a variety of strains, with MenB being the most common (42 out of 56 isolates), and distinct geographical distributions of certain clones in Newfoundland and Labrador versus New Brunswick and Nova Scotia.
  • - Vaccine predictions indicated that 54.8% of MenB strains were likely covered by the MenB vaccine Bexsero, while a high percentage (95.3%) could be covered by Trumenba, highlighting the importance of ongoing surveillance in IMD. *
View Article and Find Full Text PDF

Admixture estimation plays a crucial role in ancestry inference and genome-wide association studies (GWASs). Computer programs such as ADMIXTURE and STRUCTURE are commonly employed to estimate the admixture proportions of sample individuals. However, these programs can be overwhelmed by the computational burdens imposed by the 10 to 10 samples and millions of markers commonly found in modern biobanks.

View Article and Find Full Text PDF

Ignavigranum ruoffiae is a rare human pathogen. Strain CPL 242382-20 was isolated in Manitoba, Canada, from a breast cyst. Whole-genome sequencing was performed with the Oxford Nanopore Technologies MinION and Illumina MiSeq platforms.

View Article and Find Full Text PDF

Studies of moral injury among nonmilitary samples are scarce despite repeated calls to examine the prevalence and outcomes of moral injury among civilian frontline workers. The purpose of this study was to describe the prevalence of moral injury and to examine its association with psychosocial functioning among health care workers during the COVID-19 pandemic. We surveyed health care workers (N = 480), assessing exposure to potentially morally injurious events (PMIEs) and psychosocial functioning.

View Article and Find Full Text PDF

Background: A resurgence of syphilis infections has been described in a number of countries including Canada in the last decade.

Methods: This study identified polymerase chain reaction (PCR) positive syphilis cases based on detection of genes (, , and ) in 3,350 clinical specimens obtained from patients in the province of Manitoba, Canada between 2017 and 2020. Patient demographics were obtained from specimen requisition forms.

View Article and Find Full Text PDF

Background: Gonorrhea, when left untreated, can enter the blood and cause disseminated gonococcal infections (DGIs). Disseminated gonococcal infections, which can include dermatitis, tenosynovitis, migratory polyarthralgia, and arthritis, have been increasing in Manitoba (MB), Canada, since 2013. Endocarditis, a rare DGI, was identified in 3 MB patients in 2018 and 2019.

View Article and Find Full Text PDF

Cysteine cathepsins are potent proteases implicated in cardiovascular disease for degrading extracellular matrix (ECM) whose structure and integrity determine the mechanical behavior of arteries. Cathepsin knockout mouse models fed atherogenic diets have been used to study their roles in cardiovascular disease, but the impacts of cathepsin knockout on non-atherosclerotic arterial mechanics are scarce. We examine arterial mechanics in several cathepsin knockout mouse lines (CatK, CatLApoE and CatSApoE) and controls (C57/Bl6, apolipoprotein E).

View Article and Find Full Text PDF

Extended-spectrum β-lactamases (ESBLs) confer resistance to extended-spectrum cephalosporins, a major class of clinical antimicrobial drugs. We used genomic analysis to investigate whether domestic food animals, retail meat, and pets were reservoirs of ESBL-producing Salmonella for human infection in Canada. Of 30,303 Salmonella isolates tested during 2012-2016, we detected 95 ESBL producers.

View Article and Find Full Text PDF
Article Synopsis
  • - The study investigated the carcinogenic effects of multiwalled carbon nanotubes (MWCNTs), specifically MWNT-7, on rats over a 2-year period, using both inhalation and intratracheal instillation methods for exposure.
  • - Findings showed significant increases in lung weight and various lung and pleural lesions, with higher incidences of lung tumors and pleural mesotheliomas in the high-dose group compared to controls.
  • - The results concluded that repeated exposure to MWNT-7 is carcinogenic to the lung and pleura in rats, highlighting potential risks associated with MWCNTs.
View Article and Find Full Text PDF

Certified disposable respirators afford important protection from hazardous aerosols but lose performance as they are worn. This study examines the effect of wear time on filtration efficiency. Disposable respirators were worn by CSIRO staff over a period of 4 weeks in early 2020.

View Article and Find Full Text PDF

A field-ready, fiber-based high spatial sampling snapshot imaging spectrometer was developed for applications such as environmental monitoring and smart farming. The system achieves video rate frame transfer and exposure times down to a few hundred microseconds in typical daylight conditions with ∼63,000 spatial points and 32 spectral channels across the 470nm to 700nm wavelength range. We designed portable, ruggedized opto-mechanics to allow for imaging from an airborne platform.

View Article and Find Full Text PDF

A PHP Error was encountered

Severity: Notice

Message: fwrite(): Write of 34 bytes failed with errno=28 No space left on device

Filename: drivers/Session_files_driver.php

Line Number: 272

Backtrace:

A PHP Error was encountered

Severity: Warning

Message: session_write_close(): Failed to write session data using user defined save handler. (session.save_path: /var/lib/php/sessions)

Filename: Unknown

Line Number: 0

Backtrace: