Difficulty swallowing, or dysphagia, affects over half of all stroke patients. Dysphagia in turn can cause patients to inhale food or drink into their lungs when trying to swallow, leading to pneumonia and increased risks of disability and death.
Identifying patients with dysphagia early allows the care team to bring in the services of a Speech Language Pathologist (SLP), who can recommend and implement strategies to reduce the risk of developing pneumonia.
How clinicians identify those patients is an area for improvement.
Screening tools, such as the Toronto Bedside Swallowing Screening Test (TOR-BSST©) developed by Krembil Affiliate Scientist Dr. Rosemary Martino’s team can identify patients at risk of dysphagia with a high degree of sensitivity. The TOR-BSST helps guide clinicians through a quick but systematic screening of the patient, including how they swallow water, to ensure any warning signs are caught and patients at risk are referred to a SLP.
However, more than half of acute stroke care institutions in Canada and the US do not use a formal screening tool. Instead, they detect swallowing problems by performing an informal assessment, in which a clinician makes a judgement as to whether a patient is at risk without evaluating all the possible symptoms.
In a recent study, Dr. Martino along with her students and colleagues used clinical data from before and after the implementation of the TOR-BSST at Toronto Western Hospital to compare the accuracy of dysphagia detection using the tool to that of the informal assessments. They found that the screening tool identified over 95% of patients at risk for dysphagia, whereas informal screens missed a high number of patients at risk: just 45% were identified and referred for specialized assessment and care.
“In an ideal health care system with unlimited resources, every patient would be seen by an SLP for a comprehensive swallowing assessment. However, in the real world properly validated screening tools are critical for directing the rarer and more expensive resources, such as an SLP, only toward those patients at risk for dysphagia,” Dr. Martino concludes.
This work was supported by the Canadian Stroke Network Summer Student Program, the Heart and Stroke Foundation, the University of Toronto and the Toronto General & Western Hospital Foundation. Dr. R. Martino holds a Tier 2 Canada Research Chair in Swallowing Disorders.
Sherman V, Flowers H, Kapral MK, Nicholson G, Silver F, Martino R. Screening for Dysphagia in Adult Patients with Stroke: Assessing the Accuracy of Informal Detection. Dysphagia. 2018 Mar 1. doi: 10.1007/s00455-018-9885-8
Looking at things from a different angle can often lead to new and better solutions. That’s because a fresh perspective can help to inspire creativity, innovative thinking and collaboration.
It’s also why Dr. Cristina Nostro and her team recently embarked on a new collaborative project to solve a particularly difficult research problem: how to reliably isolate a specific pancreatic cell type capable of improving current treatments for type I diabetes.
Type I diabetes is a chronic condition in which cells in the pancreas—known as beta cells—are destroyed so little to no insulin is produced. Without insulin, the body is unable to keep blood sugar levels within a healthy range. When blood sugar levels remain consistently high for a prolonged period of time, serious conditions can develop, including heart disease, vision loss, kidney disease and nerve damage.
Transplanting healthy beta cells into the pancreas can restore insulin production and decrease the number of insulin injections needed to maintain normal sugar levels. However, widespread use of this treatment is hampered by a limited supply of donor beta cells for transplantation.
Using stem cells, Dr. Nostro has addressed this issue by developing a reproducible method for generating large numbers of cells that can safely give rise to insulin-producing beta cells. The technique, which mimics what occurs during pancreas development, forces stem cells to mature into daughter stem cells (pancreatic progenitors) that then develop into insulin-producing beta cells.
Unfortunately, the technique also produces progenitors that mature into cells that do not produce insulin. The problem: these contaminating progenitors need to be removed before the therapeutic insulin-producing cells can be safely used in the clinic.
This new approach will help us to develop safer stem cell therapies for diabetes.”
-Dr. Cristina Nostro
Dr. Nostro teamed up with Dr. Thomas Kislinger to explore an entirely new approach to solving this problem. Together they identified specific proteins that are found on the surface of the pancreatic progenitors. They then used one of the proteins—known as Glycoprotein 2—to isolate the pancreatic progenitors and remove the contaminating cells. This allowed them to not only control the number but also the purity of the newly generated insulin-producing cells.
“Our long-term goal is to cure type I diabetes using transplants of insulin-producing cells, so it is crucial to have cells that are safe and pure,” explains Dr. Nostro. “The technique we’ve developed provides a better, more reliable method for generating large quantities of these cells for use in the clinic.”
Just like a large city, the body has a several systems in place to dispose of different types of waste. And when one of these systems malfunctions, serious problems can arise.
Dr. Tracy McGaha, a Senior Scientist at the Princess Margaret Cancer Centre, has shown that disrupting efferocytosis—the process through which dead cells are removed from the body—promotes the development of lupus. The findings of the study were published today in the prestigious journal Nature Immunology.
Lupus occurs when the immune system mistakenly attacks healthy tissues throughout the body, including those of the joints, skin, kidneys, blood, heart and lungs. The abnormal immune response can cause significant inflammation and damage to these parts of the body.
The cause of lupus and the immune mechanisms responsible for its damage remain elusive. This gap in knowledge has precluded the development of effective treatments that target the underlying cause of the disease.
“The link between lupus and efferocytosis is that they both involve the immune system,” explains Dr. McGaha. “In efferocytosis, specialized immune cells known as phagocytes seek out dead cells, then engulf and digest them—acting like the body’s trash collectors.”
The researchers showed that when phagocytes ‘eat’ dead cells, the immune system is suppressed through the action of a protein known as the aryl hydrocarbon receptor (AhR). In contrast, when phagocytes lacking AhR eat dead cells, the immune system is not suppressed and the body attacks healthy tissues, causing damage similar to what seen in lupus.
Dr. McGaha’s team also found that AhR activity can affect disease severity in an experimental model of lupus: disease symptoms worsen when AhR is inhibited, whereas disease symptoms improve when AhR is activated.
Dr. McGaha comments, “the results of our study suggest that AhR activity is a key mechanism that prevents the immune system from attacking normal tissues. We believe that this new knowledge could be exploited to not only develop new more effective treatments for lupus, but also to make the immune system better at destroying cells that have become cancerous.”
This work was supported by the National Institutes of Health, the Canada First Research Excellence Fund, the Swedish Medical Research Council, the Karolinska Institute (Sweden), the Canada Foundation for Innovation and The Princess Margaret Cancer Foundation. D De Carvalho holds a Tier 2 Canada Research Chair in Cancer Epigenetics and Epigenetic Therapy.
Shinde R, Hezaveh K, Halaby MJ, Kloetgen A, Charkravarthy A, da Silva Medina T, Deol R, Manion KP, Baglaenko Y, Eldh M, Lamorte S, Wallace D, Chodisetti SB, Ravishankar B, Lui H, Chaudary K, Munn DH, Tsirigos A, Madaio M, Grabrielsson S, Touma Z, Wither J, De Carvalho D, McGaha TL. Apoptotic cell–induced AhR activity is required for immunological tolerance and suppression of systemic lupus erythematosus in mice and humans. Nat Immunol. 2018 June. [abstract]
Two UHN researchers—Dr. Margaret Herridge and Susan Tarlo—received distinctions from the American Thoracic Society (ATS) Assembly on Critical Care.
Dr. Margaret Herridge received the Assembly on Critical Care 10th Annual Lifetime Achievement Award for her research contributions within the area of critical illness and clinical outcomes. Dr. Herridge is a Senior Scientist at the Toronto General Hospital Research Institute and Professor in the Department of Medicine at the University of Toronto. Her research group is committed to evaluating and improving long-term patient and family caregiver outcomes after critical illness.
Dr. Susan Tarlo has been selected to receive the Assembly on Environmental, Occupational and Population Health John Peters Award for her research contributions within the area of occupational lung diseases. Dr. Tarlo is a respiratory physician with a clinical and research focus on respiratory allergic responses and occupational respiratory diseases. She is also a Clinical Researcher at the Krembil Research Institute and Professor in the Department of Medicine and the Dalla Lana School of Public Health at the University of Toronto.
These awards will be presented at the ATS Critical Care assembly meeting in San Diego, California on May 21, 2018. More information on these awards and past awardees, visit the ATS website.
Congratulations Drs. Herridge and Tarlo!
A team of researchers in Toronto have developed a new way to measure visual discomfort—also known as photophobia—that could help advance our understanding of debilitating light sensitivities.
“We all experience visual discomfort at some point in our lives, for example when coming out of a cinema during daytime. However, for those with certain health conditions, such as a migraine headache, cataracts or damage to the eye, even normal light levels can be difficult to tolerate,” explains Dr. Agnes Wong, a Senior Scientist at the Krembil Research Institute.
Dr. Wong developed a new test to provide clinicians and researchers with a more rigorous way to measure visual discomfort in patients. Current approaches typically involve questionnaires or polls, which are hard to interpret and can vary according to patients' mood, health or cultural background.
The researchers designed the test to take advantage of new research suggesting that visual discomfort may be influenced by a relatively unstudied cell in the retina known as an intrinsically photosensitive retinal ganglion cell (ipRGC).
“ipRGCs are a rare type of cell located in the back of the eye and are believed to provide the brain with a general readout of ambient light levels. Although several lines of evidence have implicated ipRGCs in photobias, to date there is limited clinical data to support this,” says Marija Zivcevska, the lead author and a Master’s student under Dr. Wong.
The test that they developed uses a commercially available ‘flash stimulator’—a device that is normally used to test for vision disorders—and which was programmed to deliver tightly controlled flashes of light of varying colours. This device was linked to two push buttons, through which patients could indicate when they experienced visual discomfort.
When the test was used on a small group of adults with no history of visual disorders, the results supported the idea that ipRGCs are involved in visual discomfort. For example, they revealed that blue light is more likely to induce visual discomfort than red light—which agrees with previous findings that ipRGCs are activated when exposed to blue light.
The test—the first of its kind—provides an objective way to assess the light conditions that cause discomfort. This work represents an important first step towards improving our understanding of photobia and developing new therapies to treat this condition.
Supported by the Canada Foundation for Innovation, the John and Melinda Thompson Endowment Fund for Vision Neuroscience, the Department of Ophthalmology and Vision Sciences at The Hospital for Sick Children and the Toronto General & Western Hospital Foundation.
Zivcevska M, Lei S, Blakeman A, Goltz HC, Wong AMF. A Novel Visual Psychometric Test for Light-Induced Discomfort Using Red and Blue Light Stimuli Under Binocular and Monocular Viewing Conditions. Invest Ophthalmol Vis Sci. 2018 Mar 1. doi: 10.1167/iovs.17-23526.
Congratulations to the following three UHN scientists, who received new or renewed funding from the Canada Research Chairs (CRC) program.
Dr. Murray Krahn, Tier 1 Canada Research Chair in Health Technology Assessment (new chair)
Dr. Krahn is a world leader in the assessment of health technologies. His research evaluates the effectiveness, safety, acceptability and cost-effectiveness of health services, technologies and drugs. His findings are used to inform provincial and federal health care decision making and policies—with the aim of making new, effective health technologies available to the public and saving costs by ensuring these resources are used effectively.
Dr. Trevor Pugh, Tier 2 Canada Research Chair in Translational Genomics (new chair)
Dr. Trevor Pugh’s collaborative and clinically integrated research program aims to reveal new strategies to help the immune system destroy cancer cells—an approach known as immunotherapy. Using state-of-the-art genomic approaches, his team is creating molecular tests to predict and monitor immunotherapy efficacy.
Dr. Michael Tymianski, Tier 1 Canada Research Chair in Translational Stroke Research (renewal)
Dr. Tymianski is conducting a series of biological, preclinical and clinical investigations that could provide new therapies to prevent brain damage from stroke, and help those affected by other disorders where blood supply is restricted, such as a heart attack. His work has the potential to improve the quality of life for those who live with stroke symptoms, which can persist for a lifetime due to lasting brain damage.
The nationwide CRC program invests approximately $265 million per year to attract and retain Canada’s most accomplished and promising researchers. Chair holders demonstrate research excellence, provide key insights, improve quality of life of Canadians, strengthen competiveness and help train the next generation of researchers. These outstanding UHN researchers are among the 28 University of Toronto professors who received funding from the program.
