Reducing infectivity of HIV upon exposure to surfaces coated with N,N‐dodecyl,methyl‐polyethylenimine

The infectivity of high‐titer, cell‐free HIV in culture media and human milk is rapidly reduced upon exposure to polyethylene slides painted with the linear hydrophobic polycation N,N‐dodecyl,methyl‐polyethylenimine (DMPEI). Accompanying viral p24 protein and free viral RNA analysis of solutions exposed to DMPEI‐coated surfaces suggests that virion attachment to the polycationic surface and its subsequent inactivation are the likely mechanism of this phenomenon. Biotechnol. Bioeng. 2013; 110: 2058–2062. © 2013 Wiley Periodicals, Inc.     

Composition and Variation of the Human Milk Microbiota Are Influenced by Maternal and Early-Life Factors

1. Download high-res image (199KB)
2. Download full-size image

     

From the ape's dilemma to the weanling's dilemma: early weaning and its evolutionary context

Although humans have a longer period of infant dependency than other hominoids, human infants, in natural fertility societies, are weaned far earlier than any of the great apes: chimps and orangutans wean, on average, at about 5 and 7.7 years, respectively, while humans wean, on average, at about 2.5 years. Assuming that living great apes demonstrate the ancestral weaning pattern, modern humans display a derived pattern that requires explanation, particularly since earlier weaning may result in significant hazards for a child. Clearly, if selection had favored the survival of the child, humans would wean later like other hominoids; selection, then, favored some trait other than the child's survival. It is argued here that our unique pattern of prolonged, early brain growth--the neurological basis for human intellectual ability--cannot be sustained much beyond one year by a human mother's milk alone, and thus early weaning, when accompanied by supplementation with more nutritious adult foods, is vital to the ontogeny of our larger brain, despite the associated dangers. Therefore, the child's intellectual development, rather than its survival, is the primary focus of selection. Consumption of more nutritious foods--derived from animal protein--increased by ca. 2.6 myr ago when a group of early hominins displayed two important behavioral shifts relative to ancestral forms: the recognition that a carcass represented a new and valuable food source-potentially larger than the usual hunted prey-and the use of stone tools to improve access to that food source. The shift in the hominin "prey image" to the carcass and the use of tools for butchery increased the amount of protein and calories available, irrespective of the local landscape. However, this shift brought hominins into competition with carnivores, increasing mortality among young adults and necessitating a number of social responses, such as alloparenting. The increased acquisition of meat ca. 2.6 Ma had significant effects on the later course of human evolution and may have initiated the origin of the genus Homo.     

Infant and child diet in Neolithic hunter-fisher-gatherers from Cis-Baikal, Siberia: intra-long bone stable nitrogen and carbon isotope ratios

Analysis of stable nitrogen and carbon isotopes (δ(15) N and δ(13) C) from subadults and adults allows for assessment of age-related dietary changes, including breastfeeding and weaning, and adoption of an adult diet. In one of the first studies of hunter-fisher-gatherer subadults from Eurasia, three Neolithic (8,800-5,200 calBP) mortuary sites from southwestern Siberia are analyzed to evaluate hypothesized differences in weaning age between Early versus Late Neolithic groups. An intra-individual sampling methodology is used to compare bone formed at different ages. Collagen samples (n = 143) from three different growth areas of long bones-the proximal metaphysis, diaphysis, and distal metaphysis-were obtained from 49 subadults aged birth to 10 years. In infants (birth to 3 years, n = 23) contrasting the δ(15) N values of the metaphysis, which contains newer bone, to the δ(15) N values of the diaphysis, which contains older bone, permits a more precise determination of breastfeeding-weaning status. In Early and Late Neolithic groups breast milk was the major protein source until the age of 2-3 years. However, there are differences in the age of weaning completion and duration: Early Neolithic groups weaned their infants at a later age and over a shorter amount of time. Differences may have affected infant morbidity and mortality, and female fecundity and inter-birth intervals. Stable isotope values in older subadults (4-10 years, n = 26) do not differ from adults suggesting the absence of age-based food allocation.     

A distinct clade of Bifidobacterium longum in the gut of Bangladeshi children thrives during weaning

1. Download : Download high-res image (142KB)
2. Download : Download full-size image

     

Distribution of postpartum amenorrhea in rural Bangladeshi women

Previous studies of postpartum amenorrhea (PPA) demonstrated distinct subgroups of women with short and long durations of amenorrhea. This phenomenon was attributed to cases where breastfeeding is absent because of pregnancy loss or infant death, or confusion of postpartum bleeding with resumption of menses. We explored these ideas using data from an 11-month prospective study in Bangladesh in which 858 women provided twice-weekly interviews and urine specimens for up to 9 months; 300 women were observed while experiencing PPA. The resulting exact, interval-censored, or right-censored durations were used to estimate parameters of two-component mixture models. A mixture of two Weibull distributions provided the best fit to the observations. The long-duration subgroup made up 84% (+/- 4% SE) of the population, with a mean duration of 457 (+/- 31) days. The short-duration subgroup had a mean duration of 94 (+/- 17) days. Three covariates were associated with the duration of PPA: women whose husbands had high-wage employment had a greater probability of falling in the short-duration subgroup; women in the long-duration subgroup whose husbands seasonally migrated had shorter periods of PPA within the subgroup; and mothers in the short-duration subgroup who gave birth during the monsoon season experienced a shortened duration of PPA within the subgroup. We conclude that the bimodal distribution of PPA reflects biological or behavioral heterogeneity rather than shortcomings of data collection.