Philip Chan, PhD Professor
Department of Gynecology and Obstetrics
Department of Physiology and Pharmacology
School of Medicine
Loma Linda University
Loma Linda, CA 92350
Phone: (909) 558-2851, extension 81397
Fax: (909) 558-2450
pchann@yahoo.com
The goals are to identify normal and altered reproductive cells and to develop and improve clinical diagnostic and treatment procedures for infertile couples in order to help them conceive and have children. The nature of DNA fragmentation in apoptotic human sperm cells and the relationship to the fertilization of the oocyte and subsequent embryonic development are studied using fluorescent and light-microscopic molecular techniques. Preimplantation genetic diagnosis consisting of in-situ hybridization of probes to the chromosomes of separated blastomeres are used to examine the role of aneuploidy and other abnormal embryo conditions in causing miscarriages. Several studies have been carried out to investigate the role of autocrine-regulated protein factors differentially secreted by X- or Y-bearing spermatocytes to control viscosity of seminal plasma. Furthermore, research into developing a portable glass capillary electrophoresis method has uncovered the presence of cell-free DNA actively secreted or released by apoptotic cells in the human male reproductive tract. The seminal cell-free DNA has been correlated to various sperm conditions and the significance of its delivery from male to female has yet to be ascertained. An interesting finding in animal models is the vertical transmission of viral DNA (such as human papillomavirus E6-E7 types 16 and 18) by sperm vectors swimming and making contact with implanting embryos in the female. The hatching blastocyst stage appears most vulnerable and raises the possibility of noninvasive in utero embryo gene therapy to correct defective genes. Early embryonic cell division is also susceptible to nanoparticles and the cleavage mechanism is partially inhibited. Nevertheless, the embryos remain viable with suppressed apoptosis. Research here and elsewhere is helping to advance assisted reproductive technologies with the ultimate goal of helping patients diagnosed with infertility.
Siddighi S, Patton WC, Jacobson JD, King A, Chan PJ . Correlation of sperm parameters with apoptosis assessed by dual fluorescence DNA integrity assay. Arch Androl. 2004 Jul-Aug;50(4):311-4.
Bouma CL, Patton WC, Jacobson JD, King A, Chan PJ. Sperm apoptosis in nonpregnant luteal phase sera after in vitro fertilization as assessed by comparative genomic hybridization. Arch Androl. 2004 Jan-Feb;50(1):41-4.
Rowland SC , Jacobson JD, Patton WC, King A, Chan PJ. Dual fluorescence analysis of DNA apoptosis in sperm. Am J Obstet Gynecol. 2003 May;188(5):1156-7.
Caffrey AS, Patton WC, Corselli JU, Swensen RE, King A, Chan PJ. Cyclooxygenase (COX)-2 and granulosa cell apoptosis in vitro. J Assist Reprod Genet. 2002 Dec;19(12):577-81.
Maxwell DT, Jacobson JD, King A, Chan PJ. Effect of pentoxifylline on tumor suppressor and proto-oncogene apoptosis in sperm. J Assist Reprod Genet. 2002 Jun;19(6):279-83.
Lee CA, Huang CT , King A, Chan PJ. Differential effects of human papillomavirus DNA types on p53 tumor-suppressor gene apoptosis in sperm. Gynecol Oncol. 2002 Jun;85(3):511-6.
Chan PJ , Mann SL, Corselli JU, Patton WC, King A, Jacobson JD. A simple DNA disc chip in a microarray design based on modified comparative genomic hybridization for sperm DNA analysis. Fertil Steril. 2002 May;77(5):1056-9.
Lindley EM, Jacobson JD, Corselli J, King A, Chan PJ. Cryopreservation of human cumulus cells for co-cultures and assessment of DNA damage after thawing using the comet assay. J Assist Reprod Genet. 2001 Oct;18(10):534-8.
Chan PJ , Corselli JU, Patton WC, Jacobson JD, Chan SR, King A. A simple comet assay for archived sperm correlates DNA fragmentation to reduced hyperactivation and penetration of zona-free hamster oocytes. Fertil Steril. 2001 Jan;75(1):186-92.
Chan PJ. Sperm-mediated DNA transfer to cells of the uterus and embryo. Mol Reprod Dev. 2000 Jun;56(2 Suppl):316-8. Review.
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Last Revised: Tue, Jun 27, 2006