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K Hsieh

Publications and source records attributed to K Hsieh.

23 records · Page 2Linked to original sources

Angiotensin II analogues. 13. Role of the hydroxyl group of position 4 tyrosine in pressor activity.

In order to determine the features of the phenolic ring in position 4 of [Asn1,Ile5]angiotensin II that contribute to pressor activity, analogues with selected aromatic substituents were synthesized by the solid-phase method. They showed pressor activities in the rat: [Asn1,Phe(4-NH2)4]AII, 24%; [Asn1,Phe(4-NO2)4AII, 0.1%; [Asn1,Tyr(3,5-Me2)4]AII, 2.2%; [Asn1,D-Tyr(3,5-Me2)4]AII, 1.4%. These results indicate that the activity contributed by the aromatic character of the phenyl ring in the side chain of position 4 is enhanced by a group in the para position that may function as a proton donor in hydrogen-bond formation. Bulky substituents ortho to this hydrogen-bonding group decrease activity by steric interference with hydrogen-bond formation. Bulky groups than cannot act as hydrogen donors in the para position of the aromatic ring drastically decrease the activating effect of the aromatic ring on pressor activity.

Angiotensin I↗

Bone mineral density in young adult survivors of childhood cancer.

PURPOSE: Childhood cancer and its treatment can affect normal bone accretion. In this study, bone mineral density (BMD) in young adult survivors of childhood cancer is assessed to determine what cancer-related factors, patient characteristics, or treatment-related complications correlate with reductions in BMD. PATIENTS AND METHODS: The study population consisted of 40 (24 women) long-term survivors of childhood cancer treated at the Memorial Sloan-Kettering Cancer Center for a solid tumor (n = 16), lymphoma (n = 14), or acute leukemia (n = 10) at a mean age of 12.7 +/- 0.96 years and evaluated at a mean age of 25.8 +/- 0.7 years. Dual energy X-ray absorptiometry was used to determine BMD of the lumbar spine, femoral neck, and total body and single photon absorptiometry was used to determine BMD of the distal radius. RESULTS: The mean BMD standard deviation score (SDS) for the patients was significantly reduced compared to controls at the distal radius (-1.57 +/- 0.18, p = 0.0001), femoral neck (-0.68 +/- 0.20, p = 0.00014), and total body (-0.33 +/- 0.15, p = 0.03) but not at the lumbar spine (-0.22 +/- 0.22, p = 0.33). Univariate analysis revealed that gonadal dysfunction (i.e., estrogen or testosterone insufficiency) (p = 0.018) was the only variable that correlated with a reduced BMD. CONCLUSION: Young adult survivors of childhood cancer have reduced BMD. Because age at study coincides with the normal age of attainment of peak bone mass and peak bone mass is a major determinant of BMD later in life, many of these patients are at increased risk for osteoporosis and fractures.

Absorptiometry, Photon↗