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T S Li

Publications and source records attributed to T S Li.

14 recordsLinked to original sources
PubMed1992

Studies of the synthesis of biomarkers. XI. Synthesis of 4,5-secocholestane and 4-methyl-4,5-secocholestane.

4,5-Secocholestane (1a) and 4-methyl-4,5-secocholestane (1b) were synthesized from cholesterol (2) in five and seven steps, respectively. The key intermediate, 5-oxo-4,5-secocholestan-4-al (7) was reduced by the Clemmensen method to afford 1a. Meanwhile, 7 underwent selective Wittig reaction, Clemmensen reduction, and hydrogenation to give another target molecule, 1b. The structure of an unknown biomarker was shown to be different from the proposed 1a by gas chromatographic and mass spectrometric comparison.

Cholestanes↗
PubMed1992

Studies of the synthesis of biomarkers. X. Synthesis of 13,17-secodiacholestanes.

13,17-Secodiacholestanes (6) were synthesized from cholesterol (1) in six steps. The key intermediates, (20R)- and (20S)-diacholest-13(17)-enes (3a and 3b), underwent ozonization and reduction to provide (20R)- and (20S)-13,17-secodiacholesta-13,17-dione (5a and 5b), respectively. On Clemmensen reduction, the diones (5a and 5b) yielded the target molecule 6. The structure of an unknown biomarker was shown to be different from the proposed 6 by gas chromatographic/mass spectrometric comparison.

Cholestanes↗
PubMed1992

Assignment of the beta-subunit of rod photoreceptor cGMP phosphodiesterase gene PDEB (homolog of the mouse rd gene) to human chromosome 4p16.

The gene encoding the beta-subunit of rod photoreceptor cGMP phosphodiesterase (gene symbol PDEB, homolog of the mouse rd gene) is mapped to human chromosome 4 using somatic cell hybrids and further localized to the chromosome band 4p16 using in situ hybridization. A mutation in the mouse gene underlies the recessive trait of retinal degeneration in the rd mouse. Thus, the human homolog is a candidate for lesions causing retinal degeneration.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1978

The effect of antibody against a purified sperm-coating antigen on human sperm.

A purified fraction of human seminal plasma containing a sperm-coating antigen and two minor contaminants was used to immunize rabbits by intravenous route. An antiserum containing only the antibody against the sperm-coating antigen as examined by immunoelectrophoresis was obtained from one rabbit. The effect of this antiserum on human sperm was examined by sperm-immobilization and sperm-agglutination tests. The results revealed that the antibody against the purified sperm-coating antigen was incapable of immobilzing or agglutinating human sperm. This indicates that the purified sperm-coating antigen is unlikely to be useful as an antifertility antigen for immunologic fertility control.

Agglutination Tests↗
PubMed1976

Purification and characterization of a sperm-coating antigen from human seminal plasma.

A sperm-coating antigen has been purified from human seminal plasma by a combination of fractionation methods including ammonium sulfate precipitation, Sephadex G-100 gel filtration, and diethylaminoethyl cellulose ion-exchange chromatography. The purified antigen was demonstrated to be immunologically identical sperm-coating antigen, not derived from blood serum but having immunologically cross-relating antigens in milk and saliva, and a glycoprotein with a molecular weight of approximately 33,000. The purpose of purifying this antigen was discussed.

Antigens↗