The study by principal researcher Tara Haas of 91亚色鈥檚 School of Kinesiology & Health Science and Muscle Health Research Centre in the Faculty of Health in collaboration with 91亚色 kinesiology Professor Michael Riddell was published online in the peer-reviewed journal in October.

Tara Haas

鈥淐ortisol is a steroid hormone normally present in our body in small amounts, but a continuous increase in cortisol levels is linked with the development of obesity and Type 2 diabetes,鈥� says Haas.聽 The research by her team looked at the effects of sustained increases in the levels of the stress hormone corticosterone (the form of cortisol found in rodents) on the smallest blood vessels, capillaries, within skeletal muscles.

What they found, says Haas, 鈥渨as a substantial reduction, by 30 per cent, in the number of capillaries within the muscle.鈥� As capillaries bring oxygen and nutrients to the muscle cells, this reduction could have significant consequences for muscle function and perhaps even blood sugar disposal.

鈥淭his is important as a reduction in the number of capillaries could influence the ability of a person to be active, which could cause their condition to worsen,鈥� says Haas. The finding may help to explain why people with Type 2 diabetes have difficulty growing new capillaries in other tissues, such as the heart.

Michael Riddell

The researchers then took a closer look at the mechanisms involved in the reduced capillary growth by using cultured endothelial cells 鈥� those cells that form capillaries 鈥� chronically treated with the stress hormone. They found that corticosterone repressed several major intracellular signal pathways involved in controlling cell proliferation and migration, which likely contributes to the lack of capillary growth.

鈥淭his research is significant because it highlights that a chronic elevation of stress hormone can have significant negative consequences to the small blood vessels within skeletal muscle that are in charge of providing much needed oxygen and nutrients,鈥� says Haas. 鈥淚t also points the way to identifying how cortisol, through its effects on blocking appropriate blood vessel growth, may contribute to cardiovascular complications of diabetes or obesity.鈥�

Skeletal muscle endothelial cells in culture

Haas says the findings warrant further research to determine if treatment with synthetic steroid hormones carries similar risks. The capillaries in the skeletal muscles studied were affected using a low, but continuous exposure, to the stress hormone. The amount of synthetic steroid hormones, such as hydrocortisone, people are usually prescribed to block inflammation in the body, can be 25 times higher than the amount used in the study.

Haas is a member of the newly formed Angiogenesis Research Group, which investigates the adaptation of the skeletal muscle capillary network to physiological and pathological conditions.聽 The research was supported by the Natural Sciences & Engineering Research Council of Canada (NSERC) Discovery Grants to Haas and Riddell, as well as awards to 91亚色 students, including Eric A. Shikatani, who was the recipient of a Heart & Stroke Foundation of Ontario Master鈥檚 Studentship Award. In addition, student Anastassia Trifonova was the recipient of a NSERC CGSM graduate scholarship, and Anna Krylova and Andrei Szigiato were recipients of NSERC Undergraduate Student Research awards.

By Sandra McLean, YFile deputy editor

Republished courtesy of YFile鈥� 91亚色鈥檚 daily e-bulletin to research stories on the research website.

The post Chronic high-levels of stress hormone could lead to heart problems appeared first on Research & Innovation.

The first annual Muscle Health Awareness Day, organized by 91亚色鈥檚聽 Muscle Health Research Centre, will bring together the latest findings on the contribution made by heart muscle and skeletal muscle to overall health and wellbeing.

A wide range of collaborative research on muscle biology research is being done at 91亚色鈥檚 Muscle Health Research Centre, by researchers from the Faculty of Health and the Faculty of Science and Engineering; scientists are examining muscle development, disease, metabolism, blood supply, injury and regeneration, as well as adaptation of muscle to exercise. Using molecular, cellular and whole-body techniques, a major goal is to learn how Canadians can benefit from exercise through adaptations in the metabolism and structure of muscle, says Professor David Hood, director of the Muscle Health Research Centre and Canada Research Chair in Cell Physiology.

Researchers from the Centre will be joined by scientists from the University of Toronto, Sick Kids Hospital, the University of Guelph, McMaster University and Brock University, who will present their findings during four sessions. More than 50 poster presentations will also be on display at Muscle Health Awareness Day, showing the wide variety of muscle research being done by graduate students.

The four sessions during Muscle Health Awareness Day include:

1. Metabolism 鈭� will provide a description of important protein and fat metabolism pathways in health and disease. Emphasis will be on how enzymes responsible for synthesizing new proteins in muscle cells are activated, and how fats are taken up into muscle cells and metabolized. This has important implications for muscle wasting conditions, as well as obesity.
2. The Cardiovascular System 鈭� will examine how heart muscle adapts to stress in various ways.聽 The session will focus on understanding how heart muscle cells respond to stressors such as exercise and heat and how novel methods can be used to identify important proteins that are found in cardiac disease conditions. It will also provide information about heart and smooth muscle signaling during hemodynamic stress, such as high blood pressure.
3. Muscle Development and Satellite Cells 鈭� will describe some of the important molecules that regulate the process by which large, mature muscle cells develop from small precursor cells that fuse together, allowing muscle contraction and providing the energy for contraction to take place. Research will also be presented about the importance of precursor cells (called satellite cells) in adult muscle, and how they respond to exercise and aging.
4. Exercise, Metabolism and Disease 鈭� will provide an understanding of important enzymes in the mitochondria that regulate carbohydrate and fat metabolism, and will relate mitochondrial function (the powerhouse of the cell) to states of physical activity and obesity in youth. Information will also be provided about muscle diseases that lead to exercise intolerance and muscle cramps.

WHEN: 聽聽聽聽聽聽聽聽聽聽聽 Friday May 28, 9am to 5 pm
WHERE: 聽聽聽聽聽聽聽聽聽 Computer Science & Engineering Lobby and Lecture Hall B, Keele campus
INFO: 聽聽聽聽聽聽聽聽聽聽聽聽聽 /mhrc/Musclehealthday.htm.
MAP:聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽 See # 19 on map, /yorkweb/maps/index.htm

By Janice Walls, media relations officer.

The post 91亚色 to host muscle and healthy living research forum Friday, May 28 appeared first on Research & Innovation.

Being seriously overweight will cut your life short, even if you experience no major health problems as a result of your condition, according to a new study by researchers in 91亚色鈥檚 Faculty of Health.

The study examined the mortality risk of more than 6,000 Americans aged 18 to 65 years over a聽nine-year span using data from the Third National Health聽& Nutrition Examination Survey.

Researchers compared metabolically normal obese people with those who had multiple metabolic risk factors known to increase one鈥檚 risk for early mortality. Surprisingly, although both groups were at elevated mortality risk, there were no significant differences in the mortality risk between the groups.

"Our findings challenge the idea of a 鈥榟ealthy鈥� obese person," says the study lead聽Jennifer Kuk, a聽professor in 91亚色鈥檚 School of Kinesiology & Health Science.聽"It doesn鈥檛 matter if you currently have no other medical problems. You are still at a similar risk level as someone who has the classic disease states triggered by obesity, such as diabetes, high blood pressure or cardiovascular problems."

Right: Jennifer Kuk

For the purposes of the study, obesity is classified as anyone with a body mass index (BMI) of over 30. BMI is a measure of body fat based on height and weight that applies to adults. A normal BMI is between 18.5 and 24.9.

Respondents were defined as metabolically normal or abnormal based on measures of blood pressure, cholesterol, blood glucose and triglycerides. Only 1.3 per cent of respondents were classified as obese but metabolically normal.

"It鈥檚 important to note that metabolicallynormal obesity is an extremely rare subtype, but when it does occur, treatment is absolutely necessary," says Kuk.

"We already know that in addition to diabetes and heart disease, obese individuals are also more likely to die from trauma and have cancer diagnosed at more advanced stages. This research reinforces the seriousness of this condition, and highlights the need for both treatment and prevention," she says.

The study, "Are Metabolically Normal but Obese Individuals at Lower Risk for All-Cause Mortality?", appears in the December issue of Diabetes Care, published by the American Diabetes Association. It is co-authored by Chris Ardern,聽a professor in 91亚色鈥檚 School of Kinesiology & Health Science.

From YFile - 91亚色's daily e-bulletin

The post 91亚色 study examines mortality risk associated with obesity appeared first on Research & Innovation.