1. Regulation of tissue uptake and metabolism/signaling properties of fatty acids, especially within the brain.
2. Genetic and dietary regulation of plasma fatty acid concentrations.

1. regulation of GLP-1 and GLP-2 synthesis and secretion by the intestine, with particular focus on extracellular nutrients and intracellular signaling pathways;
2. investigations into the mechanisms of action of GLP-1 and GLP-2 to stimulate beta cell and intestinal growth, respectively, with a major emphasis on the roles of novel intra- and extracellular mediators of these effects.

The Study of Nuclear Hormone Receptors in Metabolic Disease

Nuclear hormone receptors comprise a superfamily of ligand-activated transcription factors that regulate diverse physiological processes by coordinating concerted patterns of gene expression. The glucocorticoid receptor (GR) and liver X receptors (LXRa and LXRb) are members of this superfamily that regulate distinct but overlapping transcriptional programs including inflammation and glucose metabolism. The objective of this research program is to identify novel mechanisms of gene regulation (activation and repression) in glucose metabolism by nuclear receptors. The main projects include:

1. Understanding the molecular mechanism of glucose regulation by LXR
2. Molecular interplay between LXR and GR in glucocorticoid signaling

The overall goal of the lab is to further our knowledge of the molecular mechanisms of these signaling pathways, with the aim of identifying novel therapeutic targets for the treatment of human disease. This includes the identification of proteins regulated by nuclear receptors as well as proteins involved in the control of ligand access to nuclear receptors.

1. Co-investigator RASS Study, Mount Sinai Hospital
2. High risk feet in end-stage renal disease (sponsored by Janssen-Ortho)

Signal Transduction and Endocrine Gene Regulation in the Pituitary. The anterior pituitary produces polypeptide hormones critical for growth, , reproduction and homeostasis in vertebrate organisms. We are studying how genes that encode the pituitary hormones are controlled, and particularly how regulatory DNA elements and specific nuclear proteins confer responses to developmental and physiological signals.

Our studies have focused on Pit-1, a nuclear DNA-binding protein conserved in all vertebrates from fish to humans. Structurally related to the embryonic 'homeobox' regulators that determine body patterning in insects, Pit-1 activates transcription of specific hormone genes, including prolactin, growth hormone, and the thyroid-stimulating hormone (-subunit. In humans, mutations that disrupt Pit-1 function cause hypoplastic pituitary development and combined pituitary hormone deficiency; dwarfism and cretinism can result. By analyzing the structure and function of transcription regulators such as Pit-1, we want to better define the mechanism of hormone gene regulation in the pituitary and differentiation of specific endocrine cell types.

Neurotransmitters and peptides from the hypothalamus regulate the release of pituitary hormones and also control synthesis of these hormones at the transcriptional level. Dopamine, for example, is a potent inhibitor of prolactin gene transcription and its analogs can be used therapeutically in the management of prolactin-secreting tumors. Dopamine regulates prolactin gene function by binding to specific G-protein coupled receptors. We are interested in how the signals from activated G proteins lead to changes in gene transcription in endocrine cells, and how cell-type specific effector proteins mediate or attenuate these signals.

My research interests relating to diabetes are in the area of gestational diabetes (GDM). We are involved now in the following areas:

1. Formulating the guidelines for obstetricians for screening for GDM
2. Evaluating women's attitudes towards the risks of GDM and screening
3. Organizing a large clinical trial to assess the effect of screening and managing GDM on short and long term outcome for both mother and baby.

My research interests relate to diabetes in pregnancy.

1. We recently completed a study looking at the long term outcomes of women with type 1 and 2 diabetes who participated in our Diabetes in Pregnancy Program. We found that, although women retained much of the knowledge they had learned, and had improved their glycemic control during pregnancy, postpartum their glycemic control was not improved. One possible reason for this was their inability to continue to do frequent self-monitoring of blood glucose. This study will be published in Diabetes Care in 2006.
2. We also recently completed a study looking at the incidence of type 1 and 2 diabetes in pregnancy in Ontario . We found that the proportion of deliveries in women with diabetes increased steadily from 0.8% in 1996 to 1.2% in 2001. We also found that women with diabetes in pregnancy continue to have higher obstetrical complication and intervention rates than women without diabetes, and many do not receive recommended specialty care during pregnancy. This study will be published in Diabetes Care in 2006.
3. We are currently looking at the rate of development of type 2 diabetes after having had gestational diabetes in a pregnancy.

1. Epidemiology of type 2 diabetes and associated complications
2. Diabetes among Aboriginal Canadians

Diabetes in Ontario: Patterns of disease, treatment, and complications.

A program of health services research in which comprehensive administrative claims data are used to evaluate the magnitude and distribution of DM on a population basis, to assess selected measures of quality of care and to support interventions to improve care. Linked administrative claims data have been used to identify the Ontario residents who have been diagnosed with DM and the resulting "virtual registry" has been validated against self-reported DM in the National Population Health Survey and against primary care office charts. This database now provides a platform in which process and outcomes of diabetes care can be examined. Current projects include an examination of rates and patterns of ophthalmologic screening, a study of "time to critical event" in an incident cohort of persons with type 2 DM (where a short time between DM diagnosis and amputation, for instance, may reflect delayed diagnosis and missed preventive opportunities), patterns of urinary protein screening and models of physician service delivery. Opportunities exist for linkage to primary data sets (e.g. clinical trial enrollees) to provide efficient long term follow-up for outcomes.

Role of transcription factors and signaling molecules in hormone production, secretion and the genesis of hormone producing cells.

Insulin, glucagon, and glucagon like peptide 1 (GLP-1), producing by different types of pancreatic and gut endocrine cells, play fundamental roles in maintaining blood glucose levels. My lab is focused on studying the role of transcription factors and signaling molecules that regulate the expression of the hormone-encoding genes, the biosynthesis and secretion of these hormones, and the genesis of hormone producing cells.

Cdx2 and cAMP. We have demonstrated that the caudal homeodomain (HD) protein Cdx2 works with other transcription factors, in regulating both glucagon and insulin gene expression. Cdx2 may serve as the mediator for the second messenger cAMP in regulating gene expression, and cAMP may exert its biological functions through activating both Protein Kinase A and the newly discovered Epac signaling pathway. We plan to continue to examine how different HD protein transcription factors are working with signaling molecules in regulating cell type specific gene expression. In addition, we are studying how Cdx2 utilizes different co-factors in order to exert its multiple biological functions.

Wnt signaling pathway. We discovered that proglucagon gene in gut endocrine L cells, but not in pancreatic A cells, is among the downstream target genes of the canonical Wnt signaling pathway. The activation is at least partially mediated through the G2 enhancer element of the proglucagon gene promoter. Cell type specifically activation is attributed to the expression of TCF-4, one of the mediators of the Wnt pathway in gut cells but not in pancreas. We are now examining the role of Wnt molecules in regulating proglucagon and insulin gene expression, the secretion of GLP-1 and insulin, and the genesis of insulin producing cells.

Area of research is related to development, evaluation, and/or delivery of educational/ nursing interventions that will facilitate self-management that is effective in meeting the mutual goals of the person with diabetes and the optimal standards for practice.

The Diabetes Stages of Change (DiSC) study is a large, randomized, prospective, controlled trial of a unique intervention based on the Transtheoretical Model of Change (TTM). A second study "Outcome Evaluation of a stage-based Intensive Diabetes Therapy Education Program" is evaluating the effectiveness of a self-management education program for Intensive Therapy.

A founder-member of the Society of Obstetrical Medicine, Dr. Kenshole established and became the Medical Director of the Tri-Hospital Diabetes Education Centre at Women's College, the first such centre to be developed in Toronto. She is in active practice in the Division of Endocrinology at The New Women's College Hospital. She is the author of a chapter on the role of the internist in Chronic Wound Care, 3rd Edition (HMP Communications), the chapter on Diabetes and Pregnancy in Medical Complications during Pregnancy, 6th Edition (Elsevier) and co-authored the chapter on type 1 and type 2 diabetes in Medical Care of the Pregnant Patient (American College of Physicians).

Her clinical research interests are focused on the diabetic pregnancy (currently the HAPO study, Hyperglycemia and Adverse Pregnancy Outcome) and TRIGR (The role of cow's milk antigen in infants at increased risk for developing type 1) as well as cardiovascular disease prevention (ASPEN, statin use in prevention of vascular disease in type 2 diabetes, HOPE and HOPE-TOO (recently completed) and several registries tracking therapeutic intervention and cardiovascular outcomes.

My major clinical research areas include:

1. Clinical trials on the prevention of atherosclerosis, especially in diabetes
2. Dietary and pharmacologic treatment for obesity, hyperlipidemia and diabetes.
3. Metabolic control vs. complications of diabetes

1. Determining the mechanism of intestinal and hepatic lipoprotein overproduction in insulin resistance and Type 2 diabetes. In vivo studies in humans and animal models of disease.
2. Determining the mechanism of high density lipoprotein (HDL) lowering in hypertriglyceridemic states such as insulin resistance and Type 2 diabetes. In vivo studies in humans, animals and in vitro cell culture.
3. The effect of free fatty acids on pancreatic beta cell secretory function. In vivo experiments in humans and rats examining the role of oxidant stress, ER stress and inflammation in mediating the deleterious effects of lipids on beta cell function.
4. In vivo studies in genetically altered mice investigating the mechanisms of insulin resistance, impairment of pancreatic beta cell function and mechanism of action of pharmacological agents:
   1. Mechanism of action of dipeptidyl peptidase IV inhibitors
   2. The role of c-reactive protein (CRP) in modulating insulin action and secretion.
   3. CB1 receptor agonism and antagonism-differentiation of CNS from peripheral tissue-mediated beneficial metabolic effects.

Alzheimer disease, neurodegenerative diseases, diabetes mellitus, and complications of these disorders, in the general population and in Down syndrome.

We are presently focusing on the identification of genetic and environmental risk factors and their interactions in the above disorders, and studying the mechanisms by which such risk factors exert their effects. The objective of such studies is to identify processes that if corrected could prevent the above disorders and their complications.

My research initiatives focus on using epidemiological techniques to explore the natural history of diabetes complications and novel strategies for their prevention. My major clinical research areas include:

1. Exploring the pattern of renal function decline and its determinants early in the course of nephropathy in type 1 diabetes.
2. Characterizing the natural history of diabetic polyneuropathy and defining the best methods for clinical assessment.
3. Diabetes technologies, including the process of care for intensive insulin therapy

My present research is focused on two main areas:

1. the assessment and incorporation of new and evolving technologies in the care of children and adolescents with Type 1 diabetes,
2. involvement in clinical trials to assess, in children and adolescents with Type 1 diabetes, the effects of new insulin preparations and routes of insulin delivery.

The Role of VEGF-A in Diabetic Nephropathy

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease in North America and the largest component of total cost of diabetes care. The basic mechanisms and pathogenesis of diabetic nephropathy are not well understood. The role of vascular endothelial growth factor A in the pathogenesis of diabetic complications is suggested by increased expression of this pro-angiogenic factor in retina and glomeruli prior to the onset of major changes. Furthermore, the nephropathy in a diabetic rat model responded to reduction of systemic VEGF levels with a blocking VEGF antibody. In our lab, we have generated a number of molecular tools and mouse models that permit us to manipulate the local production of VEGF-A in the glomeruli of living mice. Through the administration of doxycycline in the drinking water of transgenic mice, we are able to upregulate the production of the major isoform of VEGF-A 5-fold. Following only 4 days of induction, these mice develop progressive albuminuria similar to clinical presentation of patients with new onset type diabetes. Following 2 months of induction, the glomeruli of these mice exhibit features characteristic of diabetic nephropathy including nodular sclerosis, basement mebrane thickening and mesangial expansion.

We will now use these murine models to further dissect the role of VEGF-A signaling in diabetic nephropathy in euglycemic and hyperglycemic settings and as a preclinical model to test the potential role of systemic VEGF inhibitors and TGF-beta inhibitors in slowing progression of diabetic changes.

1. Novel metabolic/vascular risk factors and their relevance to the early pathophysiology of type 2 diabetes and cardiovascular disease
2. Diabetes and cardiovascular disease in South Asians
3. Evaluation of beta-cell function on oral glucose tolerance test

Interaction between pancreatic islets and vascular endothelial cells is necessary for the maintenance of ß-cell mass and function. Aside from acting as a conduit for molecular oxygen, vascular endothelial cells in vivo secrete the majority of islet extracellular matrix (ECM). This ECM likely provides a permissive signal for ß-cell proliferation, contributing to the coordinated hyperplasia of these tissues during the early stages of Type 2 diabetes. This ECM also provides a reservoir for heparin binding growth factors that further modulate this hyperplasia, including fibroblast growth factor (FGF) and vascular endothelial growth factor-A (VEGF-A). We hypothesize that communication between ß-cells and vascular endothelial cells directs the proliferation and function of both tissues.

To examine ß-cell-vascular endothelial cell interaction, my lab uses a number of cutting-edge techniques: two-photon excitation microscopy, confocal microcopy, microfluidics, and live cell imaging of fluorescent proteins. Current projects use cell culture and ex vivo pancreatic islet models. These studies will advance our understanding of pancreatic islet communication, with a specific focus on the communication between ß-cell and vascular endothelial cells through FGF/FGFR1-signaling.

Principal Investigator of the NIH funded BARI 2D Study. This study is a multicentre, international prospective randomized study examining two questions in patients with type 2 diabetes and five year survival:

1. Is it better to perform early revascularization or wait for disabling events or symptoms (if in fact they even occur)?
2. Of the two strategies of achieving normoglycemia in diabetes, which is associated with a better long term outcome - insulin providing, or insulin sensitizing?

1. Hypoglycemia is the main acute complication of diabetes which limits intensive insulin treatment. The reason is poor counterregulation of all glucoregulatory hormones. One important component of this regulation is the Hypothalamic-Pituitary-Adrenal (HPA) axis. We use molecular methods to quantify expression of stress hormones and their receptors in the brain and the pituitary. This axis controls not only release of glucocorticoid hormones but is also connected to the sympathoadrenal nervous system. An additional defect observed in diabetes is dysfunction of the expression of adrenal medullary enzymes that control synthesis of epinephrine (with S. Matthews). The main factors that increase sensitivity to hypoglycaemia are antecedent hypoglycaemia and antecedent stress. We study the molecular mechanisms in the brain pituitary and adrenal medulla in uncontrolled and insulin treated diabetic rats. The defects occur not only with responses to hypoglycemia but also with responses to stress. Thus, it is clinically important that both antecedent stress and antecedent hypoglycemia can affect responses to a variety of stressors. Unravelling these mechanisms could lead to new pharmacological approaches to improve counterregulation in diabetes. Presently, our main focus is pharmacological approaches to prevent or ameliorate hypoglycemic episodes using a new approach.
2. We study the mechanisms whereby exercise and stress can delay or prevent the onset of type 2 diabetes in ZDF rats. This work involves molecular mechanisms of regeneration and maintenance of beta-cell mass and alpha-cells of the pancreas and the molecular study of the HPA axis since abnormal release of glucocorticoids affects pancreatic function. In addition, we outline the affect of exercise on oxidative stress and inflammation in animal models of Type 2 diabetes (with S. Matthews and Allen Volchuk).
3. With Dr. Wojtowicz, we study in models of Type 1 diabetes, impairment of hippocampal neurogenesis. Neurogenesis was measured using the dentate-gyrus of the hippocampus using immuno-hystochemical markers Ki67, Doublecortin, Calbindin (CaBP) and bromodeoxyuridine BrDU).

Sustained release implants for protein hormone delivery.

The focus of our research is to develop devices to administer a drug continuously over a long period of time in small doses that are within a therapeutically desirable range. The primary analytical tool we use is UV spectroscopy. We have developed a sustained release implant for diabetic research animals and for clinical treatment. We have access to the research facilities of the Division of Comparative Medicine housed in the Medical Science Building. Endocrinology is closely related to our research area. Scientists in diabetes research and diabetic subjects benefit from our research.

1. Roles of lpdl and lpdlr lipases in lipid/lipoprotein and glucose metabolism
2. Zebrafish model to study pancreas development and regeneration