Martin Richter

Université de Sherbrooke | UdeS · Department of Medicine

Isoliquiritigenin (1) possesses a variety of biological activities in vitro. However, its poor aqueous solubility limits its use for subsequent in vivo experimentation. In order to enable the use of 1 for in vivo studies without the use of toxic carriers or cosolvents, a phosphate prodrug strategy was implemented relying on the availability of phen...

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a master regulator that promotes the transcription of cytoprotective genes in response to oxidative/electrophilic stress. Various Michael–type compounds were designed and synthesized and their potency to activate the Keap1/Nrf2/ARE pathway was evaluated. Compounds bearing two Michael–type accept...

Objectives: To determine the modifiable factors affecting glucose variability in people with cystic fibrosis (CF). CF-related diabetes (CFRD) is the most common complication of CF, and its presence increases morbidity and mortality in patients. Patients with CF (with and without CFRD) have potentially harmful glucose fluctuations and glucose excur...

The differentiation of mouse spermatids is one critical process for the production of a functional male gamete with an intact genome to be transmitted to the next generation. So far, molecular studies of this morphological transition have been hampered by the lack of a method allowing adequate separation of these important steps of spermatid differ...

Despite a relatively low fatality rate, the 2009 H1N1 pandemic virus differed from other seasonal viruses in that it caused mortality and severe pneumonia in the young and middle-aged population (18-59 years old). The mechanisms underlying this increased disease severity are still poorly understood. In this study, a human isolate of the 2009 H1N1 p...

The host response to influenza virus infection is characterized by an acute lung inflammatory response in which intense inflammatory cell recruitment, hypercytokinemia, and high level of oxidative stress are present. The sum of these events contributes to the virus-induced lung damage that leads to high a level of morbidity and mortality in suscept...

The clinical benefits of oseltamivir (Tamiflu) are well established, but the effects of antiviral treatment on the immune response are poorly understood. By use of flow cytometric analyses and the mouse model, we thoroughly investigated the impact of such a treatment on the immune response and the generation of protective immunity to influenza. We...

Skeletal muscle has strong regenerative capabilities. However, failed regeneration can lead to complications where aberrant tissue forms as is the case with heterotopic ossification (HO), in which chondrocytes, osteoblasts and white and brown adipocytes can arise following severe trauma. In humans, the various HO cell types likely originate from mu...

Antivirals that are currently used to treat influenza virus infections target components of the virus which can mutate rapidly. Consequently, there has been an increase in the number of resistant strains to one or many antivirals in recent years. Here we compared the antiviral effects of lysosomotropic alkalinizing agents (LAAs) and calcium modulat...

Transient DNA breaks and evidence of DNA damage response have recently been reported during the chromatin remodeling process in haploid spermatids, creating a potential window of enhanced genetic instability. We used flow cytometry to achieve separation of differentiating spermatids into four highly purified populations using transgenic mice harbor...

Influenza viruses do not encode any proteases and must rely on host proteases for the proteolytic activation of their surface hemagglutinin protein in order to fuse with the infected host cell. Recent progress in the understanding of human proteases responsible for influenza hemagglutinin activation has led to the identification of members of the t...

The purpose of this study was to determine whether plasma biomarkers reflect changes in lung function and respiratory exacerbations associated with CF lung disease. Plasma human leukocyte elastase/alpha1 antitrypsin complex (pHLE complex) values were measured in 28 adult CF patients and 47 healthy volunteers and correlated with forced expiratory vo...

The airway and alveolar surface is exposed daily to 8,000 L of air containing oxygen, particles, bacteria, allergens and pollutants, all of which have the potential to induce oxidative stress within cells. If one is also a cigarette smoker, then the exposure to reactive oxidants increases exponentially. More than any other tissue, the lung is at ri...

Infectious dose of influenza determines inflammatory, innate, and adaptive CD8+ T cell responses, and modulates central and effector protective immunity to heterologous infection. Factors from the virus and the host contribute to influenza virus pathogenicity and to the development of immunity. This study thoroughly examined the effects of an initi...

Growing evidence indicates that influenza pathogenicity relates to altered immune responses and hypercytokinemia. Therefore, dampening the excessive inflammatory response induced after infection might reduce influenza morbidity and mortality. Considering this, we investigated the effect of the anti-inflammatory molecule 15-deoxy-Δ(12,14)-prostaglan...

Previous work has pointed to a role for the Wnt canonical pathway in fibrosis formation in aged skeletal muscles. In the present study, we studied the dystrophic mdx mouse, which displays skeletal muscle fibrosis. Our results indicated that the muscle resident stromal cell (mrSC) population in the muscles of dystrophic mice is higher than in the mu...

Activation of naive T cells by antigen requires signaling via the T-cell receptor (TCR) and co-stimulatory receptors. However, in response to homeostatic pressure, T lymphocytes undergo cytokine-driven proliferation without overt antigen stimulation. Homeostatic expansion is more pronounced in the CD8+ T-cell compartment, with memory CD8+ T cells s...

Primary viral infections of the lung induce potent effector CD8 T cell responses. To function in the influenza-infected airways, CD8 T cells must be able to resist cell death. The majority of the CD8 T cells in the airways and lung parenchyma expressed CD49a, the alpha-chain of the type IV collagen receptor VLA-1, and these cells were highly activa...

Interactions between the liver and CD8+ T cells can lead to tolerance, due in part to CD8+ T cell death. To test whether this was the case in an extrahepatic infection, we investigated the fate and effector capacity of intrahepatic CD8+ T cells during lung-restricted influenza infection in mice. Virus-specific T cells accumulated in livers without...

The role of endothelin, PAF and thromboxane A2 in airway hyperreactivity (AHR) to carbachol induced by ovalbumin sensitization and challenge in Balb/c mice was investigated. Ovalbumin sensitization and challenge induced significant AHR to carbachol in actively sensitized and challenged mice. Treatment of these mice with the PAF antagonist CV-3988 (...

Most viral infections occur in extralymphoid tissues, yet the mechanisms that regulate lymphocytes in these environments are poorly understood. One feature common to many extralymphoid environments is an abundance of extracellular matrix. We have studied the expression of two members of the beta(1) integrin family of collagen-binding receptors, alp...

Most viral infections occur in extralymphoid tissues, yet the mechanisms that regulate lymphocytes in these environments are poorly understood. One feature common to many extralymphoid environments is an abundance of extracellular matrix. We have studied the expression of two members of the β1 integrin family of collagen-binding receptors, α1β1 and...

This review summarizes the present understanding of the biology of CD4 T cells during both the acute and memory phases of the response to nonpersisting viral infection. Elucidating the precise role of CD4 T cells in viral infections has been a challenge due to characteristics intrinsic to the CD4 response and the slow development of tools that allo...

Asthma is characterized by an increased production of eosinophil-active C-C chemokines by the airway epithelium. Recent studies have identified the presence of important quantities of labile zinc in the conducting airways. We hypothesized that modulation of this labile zinc could influence the production of proinflammatory chemokines in respiratory...

Human serum albumin (HSA) is a cystine-rich serum protein taken up by many cells through receptor-mediated and fluid-phase endocytosis. We hypothesized that HSA may play a role in modulating cellular antioxidant redox signaling. Lung epithelial cells (A549), fibroblasts (HFL1), and blood lymphocytes had increased glutathione (GSH) levels after 8 h...

The effects of several mediators including prostanoids, neuromediators, bioactive peptides and leukotrienes were investigated on the trachea, upper bronchi, lower bronchi and lung parenchyma of selected strains of mice mounted in a cascade superfusion system. The upper airways (trachea, upper bronchi) responded with greater maxima than lower airway...