[The social-and-psychological factors related to prevalence of breast feeding].

A comprehensive social-and-hygienic study of families with newborns was undertaken for the purpose of defining the factors influencing the prevalence and duration of breastfeeding. A special questionnaire was worked out that was addressed to 1088 families in 3 cities, i.e.

[Affinity modification of 80S ribosomes from human placenta with mRNA analogs--derivatives of oligouridylates with and alkylating group at the 5'-end].

Affinity labelling of 80S ribosomes from human placenta with 4-(N-methylamino-N-2-chloroethyl)benzylmethylphosphoramide derivatives of oligouridylates pUn (n = 3, 4, 6, 12) bearing 5'-32P-label was studied. Complexes of these derivatives with 80S ribosomes where codon-anticodon interaction took place either in P-site (in the case of pU3-and pU4-derivatives), or in P- and A-site simultaneously (in the case of pU6- and pU12-derivatives) were obtained in the presence of Phe-tRNA(Phe). All the reagents modified only the 40S subunit.