Structural characterization of sialylated tetrasaccharides and pentasaccharides with blood group H and Le(x) activity isolated from bovine submaxillary mucin.

In this study we have investigated the structures of a sialylated tetrasaccharide and two sialylated pentasaccharides released from bovine submaxillary mucin by alkaline borohydride treatment and isolated by high-performance liquid chromatography. The tetrasaccharide contained NeuGc, while one of the pentasaccharides contained NeuAc and the other contained NeuGc. All three oligosaccharides contained the core type-3 structure (GlcNAc beta 1----3GalNAcol). The structures, determined by a combination of one- and two-dimensional 1H-NMR spectroscopy at 270 MHz and methylation analysis involving gas-liquid chromatography/mass spectrometry, were as follows: [formula: see text]. The oligosaccharides occurred in the approximate molar ratios, 1.0:0.6:0.3. This is the first report of these oligosaccharides in bovine submaxillary mucin. 1H-NMR data for structures A1/2c and A1/2e, which are novel structures, are presented for the first time. Oligosaccharide A1/2e contains the blood-group-H type-2 antigenic determinant while oligosaccharide A1/2d contains the Lewis(x) determinant.

Determinants of job turnover of young men and women in the United States: a hazard rate analysis.

PIP: Hazard models were used to examine the expected job tenure of male and female entrants to the full-time labor force after they appear to have completed their full-time education. Other analysts who have examined the relative quit rates of men and women have not limited their analyses to the 1st job, but they have implicitly assumed that hazard rates from 1st jobs are completely representative of hazard rates from any random nth job. This is 1 of the most important and questionable aspects of their implicit assumption that job terminations can be treated in semi-Markov processes. The basic goal is to analyze the hazard rates for a set of workers who have in some sense terminated their primary tie to education and have shifted toward a primary commitment to the labor force. The compilation of the durations of 1st full-time (20 or more hours/week) jobs yielded a sample of 1431 men and 1527 women. Female workers on average had about a half-year less education than the men: 12.47 years compared to 12.89 years. The percentage of workers with less than a high school education was similar for men (18.1%) and women (18.6%). The percentage of workers with 18 or more years of education was almost 6 times as high for men as for women: 2.73% versus 0.46%. The racial composition of the sample reflected the higher labor force participation rates of black women over white women. For the male sample, 73.2% of the workers were white and 25.7% were black. For the female sample, 70.7% were white and 28.3% were black. For the period 1968-71, female full-time workers quit their 1st job after completing school at substantially higher rates than male workers. This finding was robust to several different model specifications and selection criteria, as well as to estimations with and without duration dependence and with and without corrections for unobserved heterogeneity. While changes were not marked, increasing the definition of full-time employment from 20-30 hours reduced overall quit rates and tended to widen the tenure gap between men and women workers. Treating layoffs as completed spells of work raised overall quit rates and tended to narrow slightly the male-female tenure differential. Also contrary to the other microdata studies, the following were among the results: increased education had a significant and negative effect on quitting for both men and women; the unemployment rate had a significant, negative effect on quit rates for men; the hazard rates for women did not decline monotonically with duration but increased sharply after 18 months; and nonwhites did not have lower rates than whites.^ieng