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Research interests: Reproductive Physiology
My research interest is on the vascular control in the testis and the mechanisms of endometrial bleeding induced by progestin-only contraceptives.
Two aspects of vascular control in the testis are being examined; they are the control of blood flow and new blood vessel formation (i.e. angiogenesis). Studies in my laboratory have demonstrated that a large number of vasoactive substances found locally within the testis is having potent effects on the reactivity of the testicular artery and the testicular blood flow rate. These studies have been performed using two techniques: (i) a video microscopy method for examining the reactivity of testicular blood vessels to vasoactive substances in situ, and (ii) a hydrogen gas clearance method for the measurement of testicular capillary blood flow. Other studies are now being planned to examine whether under different physiological and pathophysiological states of the testis, the changes in testicular blood flow are linked to altered responses of the testicular vasculature to one or more of these vasoactive factors. In relation to the work on the control of testicular blood vessel growth or angiogenesis, the main focus is on the possible role of the vascular endothelial growth factor (VEGF) and the involvement of the testicular macrophages. Another new area of work which I have recently started to look into is the role of VEGF in Leydig cell - testicular macrophage interaction.
Studies on the mechanism of endometrial bleeding induced by progestin-only contraceptives involve the use of immunohistochemical techniques to identify local changes in the structure and/or function of the endometrial tissue, which may account for the increased incidence of irregular bleeding in this patient group. The markers that are of interest include adhesion molecules, oestrogen and progesterone receptors, basement membrane proteins, endothelial cell markers and cytoskeletal proteins, and factors important to endometrial haemostasis.
Selected Publications:
* P.A.W. Rogers, C.L. Au, B. Affandi (1992) Effects of Norplant on the endometrial microvasculature. In: Steroid Hormone and Uterine Bleeding, N.J. Alexander & C. d'Arcangues (ed.), AAAS Press, Maryland, p.59-66.
* C.L. Au & P.A.W. Rogers (1993) Immunocytochemical determinations of changes in von Willebrand factor levels in endometrium of normal women during the menstrual cycle. Human Reproduction 8: 17-23.
* P.A.W. Rogers, C.L. Au & B. Affandi (1993) Endometrial microvascular density during the normal menstrual cycle and following exposure to long-term levonorgestrel. Human Reproduction 8: 1396-1404.
* H.O.D. Critchley, D.A. Bailey, C.L. Au, B. Affandi, and P.A.W. Rogers (1993) Immunohistochemical sex steroid receptor distribution in endometrium from long-term subderinal levonorgestrel users and during the normal menstrual cycle. Human Reproduction 8: 1632-1639.
* C.L. Au, H.S. Chung, H.C. Pang and L.F. Chan (1996) Human chorionic gonadotrophin (hCG)- induced endothelial cell proliferation in adult rat testes and its dependence on the presence of Leydig cells. J. Physiol. 497: 71P.
* C.L. Au, L.F. Chan, W.C. Wan & W.M. Lee (1997) Localization of vascular endothelial growth factor (VEGF) in rodent testes. Int. J. Androl. 20 (suppl.1): 72.
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