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S Lyle

Publications and source records attributed to S Lyle.

24 records · Page 2Linked to original sources
PubMed1991

Synthesis and utilization of a nonhydrolyzable phosphoadenosine phosphosulfate analog.

3'-Phosphoadenosine 5'-phosphosulfate (PAPS) functions as the high-energy sulfate donor for sulfate ester synthesis in all higher organisms. This activated sulfate, like its adenosine 5'-phosphosulfate precursor, is both chemically labile and vulnerable to sulfohydrolase degradation. These obstacles have limited the utility of the native PAPS in the purification and mechanistic description of the numerous PAPS-utilizing enzymes. This paper describes the synthesis of the 2'- and 3'-isomers of a nonhydrolysable, and thus stable, PAPS analog, beta-methylene-PAPS, from the previously described beta-methylene-APS (L. Callahan et al., Anal. Biochem. 177, 67-71, 1989). The method involves phosphorylation of beta-methylene-APS with trimetaphosphate and separation of the resulting mixed 2'(3')-isomers by ion-pair reverse-phase HPLC. The utilization of this analog as an inhibitor of APS kinase and PAPS translocase, two of the numerous PAPS-utilizing activities, as well as an affinity ligand for purification of APS kinase, is described.

Animals↗
PubMed1991

Relationship of total serum IgE levels in cord and 9-month sera of infants.

To characterize IgE levels at birth and changes in those levels during the first year of life and to identify factors that might influence IgE levels in infancy, we measured IgE levels in 1074 umbilical cord sera and in 697 sera obtained at 9 months of age in a healthy population of infants enrolled at birth into the Children's Respiratory Study in Tucson, Arizona, U.S.A. Serum IgE levels at birth and 9 months were log normally distributed with geometric means of 0.09 and 3.87 IU/ml, respectively. Cord serum IgE levels were unaffected by maternal smoking. Levels varied according to month of birth with a nadir in September. Cord and 9-month serum IgE levels were higher in boys than in girls, Hispanics compared with Anglos, and infants who developed eczema compared with those who did not, but the mean increases in log IgE from birth to 9 months were not significantly affected by these factors. A significant correlation between IgE levels at cord and 9 months was observed (r = 0.44; P less than 0.0001). Also, mean log IgE levels at 9 months in infants grouped according to cord serum IgE levels maintained the same rank order of mean values as the cord groups. These data indicate that 9-month IgE levels are influenced by cord serum IgE levels and that the main influence of gender, ethnicity and susceptibility to eczema on IgE levels occurs before birth.

Age Factors↗
PubMed1990

Incidence and treatment of abnormal postpartum ovarian function in dairy cows.

The objectives of this study were to determine 1) the incidence of abnormal postpartum ovarian function in a large dairy herd in North Central Florida and 2) the effectiveness of gonadotrophin releasing hormone (GnRH) in treating this condition. The study was conducted from April 1988 to June 1989. The internal genitalia of the cows were initially examined per rectum (Day 0) between 19 and 29 (23 +/- 0.25) d after calving and again 14 d later (Day 14) for evidence of uterine involution and ovarian activity. The presence of a palpable corpus luteum (CL) and retrospective determination of plasma progesterone (P4) concentrations > 1 ng/ml were the criteria used to assess ovarian activity. Cows possessing a palpable CL and P4 concentrations > 1 ng/ml on Day 0 were determined to be cycling normally. A total of 1356 cows was used in this study. On Day 0, two groups were formed: Group 1 consisted of normal, cyclic cows, Group 2 of noncyclic cows. On Day 0, alternate cows in Group 2 were treated with GnRH (100 microg i.m). On Day 14, the previously nontreated cows in Group 2 were further divided into two groups, forming Group 3, nontreated cows and Group 4, cows treated with GnRH at this time. Group 5 was comprised of cows from Group 2 that did not respond to treatment with GnRH on Day 0; these cows were treated on Day 14 with GnRH (100 microg i.m). Group 6 was comprised of nontreated cows from Group 2 that responded spontaneously (presence of a CL) by Day 14. Reproductive parameters evaluated were the percentage of cows pregnant within 180 d after calving and at the end of the study, the number of days open and the number of services per conception. Data were statistically analyzed using Chi square and survival analysis. The results of this study indicate that the incidence of abnormal postpartum ovarian function in this herd was 30.2% and that the nontreated cows experienced more days open and required more services per conception than the treated cows, those that were cycling normally on the initial examination, and those that responded spontaneously by Day 14.

Journal Article↗