Day 2 :
Emory University School of Medicine, USA
Time : 09:30-10:05
Joshua Barzilay, MD, is an endocrinologist in Atlanta GA who works for the Kaiser Permanente of Georgia. He is a professor of medicine in the division of endocrinology at the Emory University School of Medicine. He has published approximately 150 peer-reviewed papers.
The microcirculation plays an important role in bone formation during the ante-natal period. It is not known whether microvascular disease in post-natal life plays a role in impaired bone health, such as osteoporosis. Here we review several epidemiological studies that we have conducted in recent years showing that hip fractures – one the most serious manifestations of osteoporosis - are associated with several markers of microvascular disease: (1) retinal vascular disease, (2) albuminuria, and (3) abnormal white matter volume on a brain MRI. We further show that the presence of albuminuria mediates the association of dementia (a brain disorder related in part to small vessel disease of the brain) with hip fracture risk. These findings, plus recent reports that specialized cells in the osseous microvasculature play an important role in post-natal bone formation, support the hypothesis that extra-osseous microvascular disease may signify the presence of osseous microvascular disease that leads to osteoporotic fractures. Finally, we review radiological studies that show diminished bone perfusion in association with osteoporosis.
University of Ljubljana, Slovenia
Time : 10:05-10:40
Robert Zorec is Professor of Pathophysiology at the University of Ljubljana, Medical Faculty, a Full Member of Academia Europaea (London) and Slovenian Academy of Sciences and Arts (cont. of Academia Operosorum Labacensis from 1693), as well as a past Member of the Committee for Advanced Medical Products at the European Medicine’s Agency (London). Dr. Zorec received his Ph.D. from the University of Ljubljana in 1986 for his work conducted at the Newcastle Medical School and at the MRC Neuroendocrinology Unit in Newcastle upon Tyne, U.K, and introduced the "patch-clamp" method in Ljubljana in 1985. Dr. Zorec postdoctoral experience was at Cambridge in Dr. W. T. Mason's laboratory.
Edocrine Hormone release engages regulated exocytosis, a multistage process involving the merger between the vesicle and the plasma membranes. This leads to the formation of a fusion pore, a channel, through which secretions are released from the vesicle lumen to the cell exterior. A stimulus may influence the pore by either dilating it completely (full-fusion exocytosis) or mediating a reversible closure (transient exocytosis). In neurons, these transitions are short-lived and not accessible for experimentation. However, in some endocrine and gliocrine cells, initial fusion pores may reopen several hundred times, indicating their stability. Moreover, these pores are too narrow to pass luminal molecules to the extracellular space, but their diameter can dilate upon stimulation. To explain the stability of the initial narrow fusion pores, anisotropic membrane constituents with non-axisymmetrical shape were proposed to accumulate in the fusion pore membrane. Although the nature of these is unclear, they may consist of lipids and proteins, including SNAREs, which may facilitate and regulate the pre- and post-fusion stages of exocytosis and the release of vesicle hormone cargo into the extracellular space.