Pushing the limits of automated glycan assembly: synthesis of a 50mer polymannoside.

Automated glycan assembly (AGA) enables rapid access to oligosaccharides. The overall length of polymers created via automated solid phase synthesis depends on very high yields at every step to obtain full length products. The synthesis of long polymers serves as the ultimate test of the efficiency and reliability of synthetic processes. A series of Man-(1 → 6)-α-Man linked oligosaccharides up to a 50mer, the longest synthetic sequence yet assembled from monosaccharides, has been realized via a 102 step synthesis. We identified a suitable mannose building block and applied a capping step in the final five AGA cycles to minimize (n - 1) deletion sequences that are otherwise difficult to remove by HPLC.

Automated glycan assembly of branched ß-(1,3)-glucans to identify antibody epitopes.

ß-(1,3)-Glucans exhibit immunomodulatory and anti-tumor effects. Since the isolation of pure ß-(1,3)-glucan oligosaccharides from natural sources is complicated, especially when certain branching patterns are desired, chemical synthesis is frequently the only means of accessing these molecules. We report the iterative automated glycan assembly (AGA) of conjugation-ready linear and branched ß-(1,3)-glucan oligosaccharides.

Identification of carbohydrate anomers using ion mobility-mass spectrometry.

Carbohydrates are ubiquitous biological polymers that are important in a broad range of biological processes. However, owing to their branched structures and the presence of stereogenic centres at each glycosidic linkage between monomers, carbohydrates are harder to characterize than are peptides and oligonucleotides. Methods such as nuclear magnetic resonance spectroscopy can be used to characterize glycosidic linkages, but this technique requires milligram amounts of material and cannot detect small amounts of coexisting isomers. Mass spectrometry, on the other hand, can provide information on carbohydrate composition and connectivity for even small amounts of sample, but it cannot be used to distinguish between stereoisomers. Here, we demonstrate that ion mobility-mass spectrometry--a method that separates molecules according to their mass, charge, size, and shape--can unambiguously identify carbohydrate linkage-isomers and stereoisomers. We analysed six synthetic carbohydrate isomers that differ in composition, connectivity, or configuration. Our data show that coexisting carbohydrate isomers can be identified, and relative concentrations of the minor isomer as low as 0.1 per cent can be detected. In addition, the analysis is rapid, and requires no derivatization and only small amounts of sample. These results indicate that ion mobility-mass spectrometry is an effective tool for the analysis of complex carbohydrates. This method could have an impact on the field of carbohydrate synthesis similar to that of the advent of high-performance liquid chromatography on the field of peptide assembly in the late 1970s.

[A study of the effect of sex composition on fertility control behavior (author's transl)].

PIP: This study attempts to analyze the effect of sex composition on fertility control behavior of Korean women. It is known that son preference still prevails in Korea although the nation's fertility declined from 6.0 in 1960 to 2.6 in 1979. Moreover, no one can assure that the fertility will continue to decrease or not as son preference still remains a barrier to family planning in Korea. With this background, it is possible to assume that Korean women's fertility control behaviors are likely to affect sex composition besides number of children. Data used in this study came from the 1979 Korean Contraceptive Prevalence Survey which was conducted jointly by KIFP and Westinghouse Health Systems in 1979. Out of the total respondents who were ever-married and aged 15-49, the 9526 women with 1, 2, 3, or 4 children were selected for this analysis. As analytical tools, ANOVA and MCA were used to test the relationships between dependent and independent variables, and to analyze the pattern of such relationships by sex-composition categories. The current status of the sex composition of Korean women was reviewed in comparison with Sheps' theoretical probability at birth by sex composition. Among several sex compositions, the preponderance of each sex deviated from his theoretical probability. Especially, the son's preponderance exceeded the probability and the daughter's did not reach the probability. This means that the current status of sex composition of Korean women is 2 sons and 1 daughter, followed by 3 sons and 1 daughter, and 1 son and 1 daughter. Conversely, the least favored sex composition was 3 daughters and 1 son and 2 daughters and 1 son. This would also indicate the other side of Korean son preference. Fertility control behaviors by sex composition varied a great deal. A higher practice rate of contraception was seen among women who had sons rather than among women with daughters. Induced abortion, one of the strongest birth control methods, showed a pattern similar to that found in contraceptive practice. It indicates that women who have achieved the favored number of sons or who have satisfied their sex combinations are going to control childbirth more actively and effectively. But those women who have only daughters or have not achieved the favored sex combination tend to neglect fertility control and are likely to progress to the next highest number of children. The results of analysis show that a woman's contraceptive practice was significantly related to sex composition, experience of induced abortion, and number of children. Contraceptive behavior was affected by these 3 variables. The most powerful effects were a result of induced abortion and sex composition. It is an unexpected result that sex preponderance for sons only is also associated with neglect of birth control. The number of induced abortions was significantly related to sex compostion, number of children, and contraceptive practice, and was also affected by these 3 variables. (author's)^ieng

[Decomposition of the increasing rate on contraceptive users during 1971-1979 (author's transl)].

PIP: Based on Kitagawa's concept of decomposition of the difference between 2 rates, the general contraceptive practice rate is analyzed in this study. Contraceptive practice was found to have increased by 15%, to 32.3%, in 1979. This could be due to several factors whose effect comes from changes in age composition among women, proportion currently married, and age specific contraceptive practice rate. The pure effect of age specific contraceptive practice was 138.8% of the increase; change of age composition was minus 14.5%, and proportion currently married minus 1.7%. The common effect of the 2 components was minus 0.26% by change in age composition and proportion currently married, minus 18.59% by common affects of age composition and age specific contraceptive practice, and minus 3.35% by the common effects of the proportion married and age specific practice. The interactional effect of the 3 components was minus 0.38%, which was insignificant. Additionally, age specific contribution to the increase was seen to be only 4.3% in the age group 15-24, 18.19% for those 25-29, 28.56% for those 30-34, 26.29% for those 35-39, and 26.29% for those 40-44. The most powerful demographic component affecting increase in practice was therefore found to be the age specific contraceptive practice rate, with age composition 2nd in importance and proportion currently married last. (Author's modified)^ieng