The role of stress, social support, and family environment in adolescent mothers' parenting.

PIP: Adolescent childbearing is a major social and economic problem in the US. The authors assessed the role of stress, social support, and family environment upon adolescent mothers' parenting behaviors. 75 African-American, mother-infant pairs participated in the study. Each mother was administered a questionnaire and observed in a ten-minute teaching task with her baby. The study found that the adolescent mother's mother was the most frequent provider of support and the baby's father was the most frequent source of conflict. Mothers who identified more individuals as a source of conflict tended to have less positive parenting behaviors. Child age and interpersonal conflict were found through analysis to be significant predictors of maternal behavior. Furthermore, social support moderated the effects of interpersonal conflict when conflicted networks were large. Parenting stress was not a significant predictor of maternal behavior.^ieng

Mapping of antigenic domains in poliovirus VP1 involved in structural rearrangements during virus morphogenesis and antigenic alterations of the virion.

Monoclonal antibodies (mAbs) directed against linear epitopes of the structural polypeptide VP1 of poliovirus type 1, Mahoney (PV1M), were used as sensitive tools to evaluate the accessibility of certain amino acid residues, both during virus morphogenesis and after conformational transitions of the capsid resulting from heat treatment (H- or 80S particles) and cell-receptor interaction (A- or 135S particles). Antibody binding sites were mapped by immunoblotting of VP1 fragments after procaryotic expression and by introduction of nested sets of deletions into recombinant VP1. The binding sites clustered at the amino- and carboxy-termini of the polypeptide, respectively. In 14S particles the amino-terminal sites were accessible for our mAbs, most likely from the inner surface of the particle. The carboxy-terminal sites became inaccessible during formation of pentamers from protomers. As shown by differential reaction of the mAbs, the amino-terminus of VP1 becomes externalized up to residues 41-55, whereas residues 56-67 remain buried during transition to both 80S and 135S particles. Carboxy-terminal residues 280-286 also become accessible to antibody binding on the surface of the altered particles. Since these residues are part of the canyon cleft of VP1, a structural rearrangement indicated by these mAbs is apparently associated with the loss of binding ability of 135S particles to the cellular receptor, which could explain the loss of infectivity of these particles.

Revertants of poliovirus escape mutants: new insights into antigenic structures.

Poliovirus variants that escape neutralization by monoclonal antibodies (mAbs) have previously been selected and characterized in order to determine antigenic sites on the surface of the virion. Phenotypic revertants of poliovirus type 1 escape mutants were selected within all three antigenic sites (sites 1, 2, and 3) on the basis of their reactivity with the selecting mAb. The phenotypic and genotypic properties of these revertants were determined by binding and neutralization assays. Sequencing of the viral RNA revealed different types of reversions. Besides reversion to wild-type genotype, we found phenotypic revertants which had amino acid substitutions differing from wild type, thus revealing amino acids that are also tolerated by the antibody. In another type of revertant, alterations in other parts of the epitope were found, providing a refined resolution of a particular antibody recognition site. Most of the revertants regained the property to be neutralized by the mAb. However, in one case they remained resistant to neutralization despite the fact that binding to the selecting antibody was reestablished. These results indicate that virus neutralization might be achieved by different mechanisms depending on the particular mAb.

Discrete-time event history analysis using segmented hazards.

Event history analysis is a means of explaining variation in the timing of events in individual life histories. This article describes methods for overcoming two difficult problems likely to be encountered in applications of event history analysis to studies of aging and human development. First, in many studies the ages of occurrence of critical life events are recorded in discrete units such as years, but the probability distributions of life events are usually specified in continuous-time form. We show how to estimate models for discrete-time data based on an underlying continuous-time specification. Second, the standard distributions for life events often fail to capture the complex age-dependence seen in actual data. We show how to construct a model using segmented hazards, that is, a composite of different functions for different segments of time. To illustrate these points, we study the age of first intercourse of 11,883 subjects from the National Longitudinal Study of Youth.

Maternal age, sociodemographics, prenatal health and behavior: influences on neonatal risk status.

The effects on neonatal outcome of maternal age, sociodemographic status, and prenatal health and behavior were assessed in a representative national sample of youth (National Longitudinal Survey of Work Experience of Youth). Primiparous women were categorized into four age-at-birth groups: 13 to 15 year old, 16 to 18 year old, 19 to 21 year old, and 22 to 30 year old. Younger mothers were lighter, gained less weight during pregnancy, and sought prenatal care later in their pregnancy. Neonates of the youngest mothers on average had lower birth weights, and shorter gestation periods. There were significant effects of maternal age, race, education, and pregnancy weight gain on the probability of giving birth to a premature or low-birth-weight infant. Our results also implicated the time of first prenatal care in the occurrence of premature delivery. We believe that interventions should emphasize the prevention of pregnancy in young adolescents and amelioration of the adverse prenatal conditions associated with living in lower socioeconomic conditions.

Association between parenthood and problem behavior in a national sample of adolescents.

The association between problem behaviors and parental status was studied in a national sample of urban (n = 1263) and rural (n = 388) young women 15 to 17 years of age. When assessed according to age at childbearing, there was a clear association between problem behavior and the birth of a first child prior to age 19 years. The three parental status groups studied appeared ordered in risk, with school-aged mothers having engaged in the most problem behaviors, and followed, in turn, by young adult mothers (ie, those who had a child between 19 and 21 years of age), and then by women who had not had a child by age 21 years. Young urban women who engaged in three or more problem behaviors were more likely than women who claimed no involvement in problem behaviors to subsequently have a child prior to age 19 years. In addition, black adolescents reported fewer problem behaviors than did white adolescents. When individual behaviors were analyzed, school-aged mothers were more likely than either young adult mothers or nonmothers to have reported school suspension, truancy, runaway, smoking marijuana, and fighting. Although similar results were found in both samples, the effects appeared more consistent for young urban women. In future studies, researchers must determine whether adolescent mothers are at risk for parenting difficulties because of their previous involvement in problem behaviors.

Communication and connectedness in mother- and father-adolescent relationships.

In Study 1, 605 adolescents estimated how well their parents knew them and said how much they cared what their parents thought about them. Sons and daughters judged that mothers knew them fairly well, but daughters judged that fathers did not know them so well. At the same time, statements of caring indicated high concern by sons and daughters for both parents. A supplemental result was that sons from white-collar families gave relatively low estimates of how much their mothers knew them and daughters from blue-collar families gave very low estimates of how much their fathers knew them. In Study 2, 52 adolescents from single-parent families and living with their mothers but not with their fathers also gave estimates for knowing and caring. Knowing followed the above pattern, with an expected lowering of estimates for fathers by sons and daughters. Further, estimates of caring declined especially for fathers by daughters. These results add to the growing literature that shows mother-adolescent and father-adolescent relationships contribute differentially to psychological development. The results seem especially relevant for adolescents' sex role development and constructed individuality as mediated through relationships with both parents.