Polymorphism of chicken CD8-alpha, but not CD8-beta

 We report here the structural basis of CD8 polymorphism in the chicken. Three chicken strains (RPRL Line 7, H.B15.H7, and H.B15.H12) have 14 nucleotide differences in the CD8A cDNA sequence causing eight amino acid replacements in the extracellular part of the molecule. Only two amino acid replacements and four silent mutations were observed in the CD8B cDNA sequence in one (H7) of the strains. Substitutions in CD8α were solely responsible for the binding of CD8-specific monoclonal antibodies, as detected by cDNA expression in COS cells. The majority of the amino acid substitutions are located in the immunoglobulin V-like domain and three of the changes (residues 30, 34, and 58) are situated in the putative major histocompatibility complex class I binding CDR1 and CDR2 regions of the chicken CD8α. CD8A polymorphism has not been reported in other species and this suggests that CD8A and CD8B have evolved under different selective pressures in the chicken. Received: 28 February 1997 / Revised: 19 April 1997     

Preparation of 9-alpha,11-xi-tritiated 17-alpha-ethynylestradiol, mestranol, estradiol-alpha-17-beta, and norethindrone

The preparation of 9alpha, 11xi-tritiated 17alpha-ethinyl estradiol, mestranol, estradiol-17beta, and norethindrone are described. Estrone-3-methyl ether was employed as starting material, and ethinylation with lithium acetylide-ethylene diamine resulted in 95% mestranol. Demethylation of mestranol with boron tribromide at 0 degrees resulted in 92% 17alpha-ethinyl estradiol. Dimethylsulfoxide was the choice of reagent for the condensation reaction which was complete at room temperature in about 4 hours. The usually less than 3% of unreacted 17-oxo product was removed by Girard separation. Demethylation of methyl ether with boran tribromide in methylene chloride resulted in an excellent yield of 17alpha-ethinyl estradiol-9alpha, 11xi-tritium. 3-methoxyestra-1,3,5-trien-17-one-9alpha, 11xi-tritium was reduced with sodium bis(2-methoxyethoxy) aluminum hydride to the 17beta-hydroxy compound and subsequent demethylation resulted in estradiol-9alpha, 11xi-tritium. The general method of Ringold et al was employed for the preparation of 17beta-hydroxy-17alpha-ethinylestr-4-en-3-one. Improvements for small scale radiosynthesis are also presented.