Olya Lechky

Two Toronto hospitals--The Princess Margaret and Mount Sinai--have the distinction of being on the cutting edge in the early detection of breast cancer.

These two pre-eminent institutions in the study, diagnosis and treatment of breast cancer are the first centres in North America to have installed full field digital mammography systems. At a recent press conference, experts hailed General Electric's Senographe 2000D as the single biggest breakthrough in mammography during the past 30 years. This claim is based on over 8,000 clinical studies performed on five prototype machines during the past decade. "Digital mammography represents a milestone in the diagnosis of breast disease and it will soon replace conventional mammography all over the world," said Dr. Patrice Brett, professor of radiology at the University of Toronto.

While conventional film mammography has been of great benefit in the screening and diagnosis of breast disease, the technique has always had inherent limitations, said Dr. Karina Bukhanov, head of the division of breast imaging, joint department of breast imaging, University Health Network and Mount Sinai Hospital. "Digital mammography will bring breast cancer diagnosis into the digital age, enabling all the benefits of modern computer technology and software to be applied to the fight against cancer," she said.

In digital mammography an electronic detector replaces the traditional film screen.

Nariman Malik, BSc

Hyperthyroidism is defined as an excess of circulating thyroid hormones, either thyroxine (T4) or triiodothyronine (T3).¹ In Canada, its prevalence is approximately 1.9% and it is ten times more common in women than in men.² The disease can present at any age but is less common before the age of 15.3

Hyperthyroidism is an important cause of morbidity in the elderly. The clinical manifestations of hyperthyroidism vary from one patient to another and no single clinical manifestation is a specific indicator of the condition. Hyperthyroidism classically presents with symptoms that affect almost every organ system.³ The typical features include: weight loss with preserved appetite, heat intolerance, nervousness, anxiety, insomnia, proximal muscle weakness, fatigue, tremor, heart palpitations, and increased frequency of bowel movements. Other general signs include hyperactivity, tachycardia, atrial fibrillation, systolic hypertension, hyperreflexia, lid lag, and eyelid retraction.

Elderly persons may present with these classic symptoms or more usually, their presentation is atypical (please refer to table 1).

Neil Fam, BSc, MSc

Diabetes is a common chronic disease characterized by metabolic abnormalities that have both acute and long term complications. In Canada, at least 1.5 million individuals (5% of the population) are afflicted by the disease, and this number is predicted to increase to 2.2 million by the year 2000. Diabetes has considerable associated morbidity and mortality. It is a major cause of coronary artery disease and stroke and is a leading cause of blindness and kidney disease in adults. Furthermore, individuals with diabetes have a shortened life expectancy when compared to those without the disease. Long-term complications occur in both type 1 and type 2 diabetes and result from the chronic hyperglycemia and hypertension associated with the disease. This article summarizes the chronic complications of diabetes, including effects on the vascular system, kidneys, eyes and nervous system.

The diabetic patient may develop one or all of a myriad of complications, including vascular disease, hypertension, retinopathy, nephropathy, neuropathy and foot disease.

Vascular Complications and Hypertension
The vascular complications of diabetes can be divided into microvascular and macrovascular disease.

A. Mark Clarfield, MD

In 1989 the first Canadian Consensus Conference on the Assessment of Dementia (CCCAD) met in Montreal to try to come to grips with the vexed question of dementia assessment. In those days, there was still a lively debate going about the extent to which dementia should be worked up in an attempt to find the "reversible" cases.

Nearly ten years later in 1998, the group reconvened to look at assessment again but extended its mandate as well. What follows is a brief "compare and contrast" essay which examines what the two meetings had in common as well as how they differed.

To start off, they were both held in the beautiful city of Montreal, in 1989 under the joint chairmanship of myself and Dr. Serge Gauthier. In 1998, Dr. Gauthier was still in charge but this time Dr. Chris Patterson of McMaster University joined as the co-chair. (In 1992, I had moved to Israel, but was honoured to be invited back.)

In 1989 before (or perhaps at the beginning of) the extensive government cutbacks, we were able to fund the meeting with 50% government money, both federal and Quebec provincial. The rest of the support came from private sources, mainly drug companies. By 1998 it seems that government wanted no part of consensus meetings at least in the field of the dementias, and they did not participate in the funding this time.

A decade ago the 38 participants were mainly Canadian with four American visitors.

D'Arcy Little, MD, CCFP
York Community Services, Toronto and
Department of Family Medicine, Sunnybrook Campus of Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario

Epidemiology
Diabetes mellitus, a metabolic disease characterized by hyperglycemia secondary to defective insulin secretion and/or action, is an extremely common, chronic illness with a high burden of potentially preventable complications. It is a leading cause of coronary artery disease, peripheral vascular disease, kidney failure, peripheral neuropathy and new-onset blindness. A full five percent of Canadians have been diagnosed with the disease, and this percentage is predicted to translate into 2.2 million cases by the year 2000. However, statistics from the United States suggest that for every person diagnosed with diabetes, another has the disease and remains undiagnosed. Appropriate screening for diabetes provides the means to identify those undiagnosed individuals who may benefit from earlier intervention.

The terms insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetes were eliminated in favour of the terms "Type 1" and "Type 2" diabetes in an effort to emphasize pathogenesis over treatment in disease diagnosis.

Lilia Malkin, BSc

Diabetes mellitus (DM) is estimated to affect approximately 1.5 million Canadians and 135 million people worldwide.^1,2 This article will review some of the recent advances in diabetes care and prevention, including non-invasive glucose monitoring, insulin delivery systems and "vaccination" to prevent the development of type I DM.

Maintenance of a physiologically appropriate blood glucose (BG) level is an essential component of diabetes control, as it has been shown to play an important role in reducing the debilitating sequellae of DM.^3,4 For many patients, good diabetes control may involve not only carefully planned meals, appropriate exercise regimens, and oral medications, but also interventions that may be invasive and painful, such as frequent BG monitoring and insulin injections. Decreasing or eliminating the discomfort associated with some of the more invasive procedures is likely to increase patients' compliance with therapeutic regimens, resulting in improved control of the disease.

The recent advent of minimally- and non-invasive BG monitors has the potential to replace, or at least decrease the use of the traditional "finger-prick" apparatus for the multitude of patients who require self-monitoring of BG levels.

Sheldon Singh, BSc
Toronto, ON and

George Fantus, MD, FRCPC,
Diabetology
Mount Sinai Hospital
Toronto, ON and
Director, Banting & Best Diabetes Centre Core Lab

In the USA, the prevalence of type 2 Diabetus Mellitus (T2DM), in individuals over 65 is estimated to be 10%. This is twice the prevalence of the overall USA population. The worldwide prevalence of T2DM is steadily increasing due to factors such as an increase in the elderly population, obesity, and decreased physical activity.

Multiple mechanisms are involved in the pathogenesis of T2DM including impaired insulin secretion by pancreatic b-cells, increased hepatic gluconeogenesis, and reduced glucose uptake by muscles and adipose tissue (see figure 1). These factors lead to hyperglycemia and in the long term, micro- and macrovascular complications. Available evidence indicates that improved glycemic control will decrease the complications of diabetes; this may be achieved with a combination of dietary, exercise and pharmacologic interventions.

Current pharmacologic agents used to treat T2DM include sulphonylureas (glibenclamide, gliclazide), biguanides (metformin), alpha-glucosidase inhibitors (acarbose), or insulin.

Neil Fam, BSc, MSc

Heart failure can be defined as a pathophysiological syndrome in which the heart fails to pump an adequate flow of blood to meet the metabolic demands of the body. This condition carries extremely high morbidity and mortality, with a five year survival rate of 50%. It is also one of the most common reasons for hospital admission in Canada. As our population ages, heart failure is becoming increasingly prevalent, placing serious strain on health care resources. In the past decade, medications such as angiotensin converting enzyme (ACE) inhibitors have been shown to improve survival in patients with heart failure. However, mortality has remained high. New research has focused on the use of b-blockers, a class of drugs traditionally used in the treatment of angina and myocardial infarction. Recently, two large randomised trials, the Cardiac Insufficiency Bisoprolol Study II (CIBIS-II) and the Metoprolol CR/XL Randomized Intervention Trial in Congestive Heart Failure (MERIT-HF) clearly demonstrated a survival benefit in heart failure patients taking b-blockers. This article summarizes the main findings of these studies and outlines the practical use of b-blockers in heart failure.

An understanding of the pathophysiology underlying heart failure is helpful in the selection of appropriate medical therapy.

Alexandra Nevin, BSc

Type II diabetes is a complicated, multifactorial disease process characterized by a relative insulin insensitivity leading to prolonged hyperglycemia. In comparison with type I diabetes, which is primarily due to the auto-immune-mediated destruction of the insulin producing beta cells of the pancreas, type II diabetes is the more predominant, generally adult- onset form, which predisposes individuals to pathological complications, and is more amenable to lifestyle modifications.

Senior citizens are the population most susceptible to type II diabetes. The Canadian Heart Health Survey reported that 13.2% of men and 12.0% of women between the ages of 65 and 74 have diabetes. In light of the aging population in Canada, researchers continue to investigate the intertwined role of genetics and the environment in the pathogenesis of type II diabetes in an effort to better understand and, ideally, to devise true preventative therapy measures to combat the disease.

Pathogenesis
Two fundamental defects underlie the pathogenesis of type II diabetes. The primary problem is the development of insulin resistance. In an attempt to compensate for the increased blood glucose load, a period of relative maladaptive hyperinsulinemia occurs.

Leora Horn, BSc, MSc

Over three hundred thousand Canadians currently suffer from Alzheimer's disease (AD) and the related dementias. AD is a degenerative disorder associated with a progressive decline in cognitive function. There is significant neuronal loss and impairment of metabolic activity in the cerebral cortex, hippocampus and subcortical structures affecting memory, language and emotion. At present, there are limited drugs used to treat the symptoms associated with the disease but there is no cure. In a recent Nature publication, Schenk et al., reported results that take the treatment of AD in a new direction by raising the possibility of vaccination as prevention against disease development. In two separate sets of experiments scientists were able to prevent the occurrence or reduce the presence of Alzheimer-like pathology in genetically engineered mice immunized with one of the proteins that may be responsible for disease evolution.¹

According to the Alz-heimer's Association of Canada, AD is the fourth leading cause of death in adults. The prevalence of AD increases exponentially with age. AD affects 1 in 100 Canadians between the ages of 65 and 74, 1 in 14 Canadians between the ages of 75 and 84 and 1 in 4 Canadians over 85. Symptoms of AD range from forgetfulness to disorientation to people, time and place resulting in an inability to function without assistance.