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Background: Twins and triplets fall behind singletons in cognitive and physical development. We analysed whether these differences are modified by family social position. Methods: IQ, height, body mass index (BMI) and elbow flexion, handgrip and knee extension strength were measured in Swedish men born between 1951 and 1976 during the conscription examination at 17 to 20 years of age. Information from Swedish registers on all siblings and parental socio-economic position were linked to these measures. Together, the measures were available for 1 140 329 singletons, 19 755 twins and 207 triplets. The data were analysed using regression analyses and fixed-effect models which compare twins and triplets with their singleton brothers. Results: Twins and triplets had slightly lower IQ, height, BMI and muscle strength than did singletons both at the population level as well as when compared with their singleton brothers. Although the differences between twins and triplets were small, they were largest in families with lower socio-economic position. We also found larger differences in IQ among the sons of mothers born before 1940. Conclusions: Twins and triplets fall slightly behind singletons in cognitive and physical development, even in early adulthood, but twins and triplets show no major differences. These differences are largest in families in a low socio-economic position. Our results underscore the importance of the postnatal environment in the development of twins and triplets and suggest that their parents, especially those in a low socio-economic position, need special support.

Background: Chest circumference (CC) is suggested to be a good indicator of early life nutrition, but little is known on the heritability of CC. Thus we analysed the effects of genetic and environmental factors on the development of CC in Japanese infants. Methods: CC was measured longitudinally from birth until 1 year of age in a cohort of 211 monozygotic and 160 dizygotic complete Japanese twin pairs born in 1989–2002. The data were analysed using applications of structural linear equation modelling for twin data. Results: No sex-specific differences in the variance components were found. Environmental factors unique to each twin explained the major part of the variation of CC at birth whereas environmental factors shared by co-twins were more important at 1–3 months of age. From 3 months of age, the effect of genetic factors become steadily stronger and they explained the majority of the variation at 1 year of age. Strong genetic continuity in the development of CC was found, but also new sets of genes were activated during the first year of life. The origin of the environmental part of the variation could be tracked before 3 months of age. A substantial part of common and specific environmental factors affecting CC affected also birthweight. Conclusions: CC is sensitive to intrauterine environmental factors, but these effects diminish during the first year of life, at least if postnatal environment is good. CC can be a useful indicator when identifying newborns who have suffered suboptimal pre-natal conditions.

Seven calystegins were isolated from the whole plant of Hyoscyamus niger . They are calystegins A 3 , A 5 , A 6 , B 1 , B 2 , B 3 , and N 1 . The structure of new calystegin A 6 was determined as 1α,2β,7α-trihydroxy- nor -tropane, and another new calystegin N 1 was elucidated to be a trihydroxy- nor -tropane alkaloid with a bridgehead NH 2 group in the place of a bridgehead OH group in calystegin B 2 . Very interestingly, on storage for a half year in a refrigerator, approximately 40% of calystegin N 1 was nonenzymically converted into calystegin B 2 . Calystegin N 1 was a weaker inhibitor of glycosidases compared to calystegin B 2 but with the same inhibitory spectrum. However, calystegin N 1 inhibited porcine kidney trehalase in a noncompetitive manner, whereas calystegin B 2 inhibited this enzyme in a competitive manner.

Dibutyltin diazide has proven to be potential in nucleophilic ring opening of a variety of oxiranes to give 1,2-azido alcohols in less than four hours (DMF at 60 °C) in fair to excellent yields.

Enhanced reactivity of tributyltin azide has been demonstrated in nucleophilic ring cleavage of oxiranes without solvent and promoter to give 1,2-azido alcohols in good to excellent yields.