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W K Chong

Publications and source records attributed to W K Chong.

82 records · Page 5Linked to original sources
PubMed1989

17-Desoxy estrogen analogues.

A series of 17-substituted, 17-desoxyestratrienes have been synthesized and tested as potential postcoital antifertility agents. Estrogen-relative binding affinities were determined, in vivo assays for estrogenic and postcoital antifertility activity were conducted in rats, and selected candidate compounds were further tested for estrogenic activity in monkeys. In the rat, the 17-desoxyestratriene derivatives 8a, 8b, and 30 have shown low estrogenic activity while retaining potent antifertility activity. Structural modifications at the outset included a variety of 17-substituents and an omission of the 17-oxygen functionality, which was previously thought to be necessary for potent activity. The 17 beta-ethyl side chain exhibited the greatest antifertility activity with the largest separation ratio to estrogenicity. Nuclear modification of 17-desoxyethylestrane derivatives at positions 7 and 11 further increased the desired separation of activity, with the 11-hydroxy moiety enhancing separation more than other features.

Animals↗
PubMed1989

11 beta-nitrate estrane analogues: potent estrogens.

Various estrane derivatives 1 reacted with cerium ammonium nitrate (CAN) selectively and efficiently to provide 9 alpha,11 beta-defunctionalized derivatives 2, which were subsequently deoxygenated at C-9 with triethylsilane/boron trifluoride etherate to the desired target 11 beta-nitratoestranes 3a, 3b, and 5. When examined for estrogenic and postcoital antifertility activity, 11 beta-nitrates 2c, 2d, and 3b most notably displayed more potent oral activity than did ethynylestradiol.

Animals↗
PubMed1988

Analogues of [(triethylsilyl)ethynyl]estradiol as potential antifertility agents.

Various 17 alpha-ethynylsteroids were prepared and derivatized as the corresponding triethylsilyl compounds 2-35, which were examined for a ratio of antifertility to estrogenic activity that would be more beneficial than that of the presently used agent. Among the triethylsilyl compounds evaluated, only 23 displayed this desired ratio, although two other compounds without the triethylsilyl moiety, 18 and 26, shared similar characteristics.

Animals↗
PubMed1987

Steroidal silicon side-chain analogues as potential antifertility agents.

A number of silicon-substituted analogues of ethynylestradiol that exhibit modified and enhanced biological activities have been synthesized. Particularly noteworthy are a group of [(trialkylsilyl)ethynyl]estradiol analogues that exhibit high antifertility potency and markedly reduced estrogenic activity. The best compounds synthesized are 17 alpha-[(triethylsilyl)ethynyl]estradiol (5) and 17 alpha-[(tert-butyldimethylsilyl)ethynyl]estradiol (33), which show a separation of antifertility from estrogenic activity in the rat. The results of structure-activity studies indicate a good correlation between the observed biological activities and the calculated van der Waals volumes of the three variable silicon substituents.

Animals↗
PubMedDate not supplied

Use of imaging for living donor liver transplantation.

Living donor liver transplantation is emerging as an alternative to cadaveric liver transplantation. The authors present multimodality images obtained in 44 cases of living donor liver transplantation. The images in this article were derived from the pre-, intra-, and postoperative imaging protocol for their institutional transplantation program. Preoperative magnetic resonance (MR) imaging in the donor allows detection of focal liver lesions and accurate determination of liver volume. The latter is crucial to ensure adequate postoperative liver function for donors and recipients. MR cholangiography depicts donor biliary anatomy. MR angiography and digital subtraction arteriography are performed to assess vascular anatomy. Intraoperative ultrasonography (US) helps determine the resection plane during donor hepatectomy. Postoperative MR imaging documents liver regrowth. MR imaging, US, and computed tomography help assess complications in donors and recipients.

Diagnostic Imaging↗