Ultrastructural Distribution of the 7 Nicotinic Acetylcholine Receptor Subunit in Rat Hippocampus

Acetylcholine (ACh) is an important neurotransmitter in the mammalian brain; it is implicated in arousal, learning, and other cognitive functions. Recent studies indicate that nicotinic receptors contribute to these cholinergic effects, in addition to the established role of muscarinic receptors. In the hippocampus, where cholinergic involvement in learning and memory is particularly well documented, 7 nicotinic acetylcholine receptor subunits (7 nAChRs) are highly expressed, but their precise ultrastructural localization has not been determined. Here, we describe the results of immunogold labeling of serial ultrathin sections through stratum radiatum of area CA1 in the rat. Using both anti-7 nAChR immunolabeling and -bungarotoxin binding, we find that 7 nAChRs are present at nearly all synapses in CA1 stratum radiatum, with immunolabeling present at both presynaptic and postsynaptic elements. Morphological considerations and double immunolabeling indicate that GABAergic as well as glutamatergic synapses bear 7 nAChRs, at densities approaching those observed for glutamate receptors in CA1 stratum radiatum. Postsynaptically, 7 nAChRs often are distributed at dendritic spines in a perisynaptic annulus. In the postsynaptic cytoplasm, immunolabeling is associated with spine apparatus and other membranous structures, suggesting that 7 nAChRs may undergo dynamic regulation, with insertion into the synapse and subsequent internalization. The widespread and substantial expression of 7 nAChRs at synapses in the hippocampus is consistent with an important role in mediating and/or modulating synaptic transmission, plasticity, and neurodegeneration

Who is responsible for the protection of children? Implicit and explicit interpretations of marketing messages

In this paper, we examine ethical issues related to advertising to children in light of evidence that people can hold &lsquo;implicit&rsquo; as well as &lsquo;explicit&rsquo; consumer attitudes. From a review of the important features of implicit versus explicit attitudes, we hypothesise three important features of implicit consumer attitudes in children. First, we suggest they are likely to be acquired automatically from, in part, exposure to marketing messages. Second, we predict that these attitudes will be resistant to change through reflection or reason by the child or other person. Third, we hypothesise that children&rsquo;s implicit consumer attitudes will be powerful predictors of their consumer choices in many situations. We discuss the implications for the ethics of marketing to children, and propose a research framework to begin investigating this important issue.<br /

Growth-defense trade-off and habitat specialization by plants in Amazonian forests

Journal ArticleTropical forests include a diversity of habitats, which has led to specialization in plants. Near Iquitos, in the Peruvian Amazon, nutrient-rich clay forests surround nutrient-poor white-sand forests, each harboring a unique composition of habitat specialist trees. We tested the hypothesis that the combination of impoverished soils and herbivory creates strong natural selection for plant defenses in white-sand forest, while rapid growth is favored in clay forests

The decline of leprosy in Japan: patterns and trends 1964-2008.

OBJECTIVE: Our purpose was to elucidate the patterns and trends of autochthonous leprosy in Japan from 1964 to 2008, to compare them with the findings from other studies of leprosy in decline, and to determine whether M. leprae transmission persists in Japan. DESIGN: Data on registered leprosy cases in Japan in the period 1964-2008 were analysed with reference to trends in case detection, geographical distribution, age at diagnosis, sex, classification, family history and broad correlation with socioeconomic conditions. RESULTS: A consistent decline in leprosy case detection was observed in all areas of the country over the period 1964-2008. Highest incidence was consistently in Okinawa, the southernmost part of Japan. Autochthonous leprosy has not been reported in anyone born in Japan since 1980. Increasing average age and a shift towards lower latitudes were demonstrated throughout the period. There was an inverse association between regional measures of wealth and leprosy incidence. CONCLUSIONS: Leprosy has declined throughout the past century in Japan. Autochthonous transmission has probably stopped in mainland Japan, but may still occur at a low level in Okinawa, the country's southernmost region. Analyses of data on autochthonous cases revealed patterns similar to those reported in other countries with declining leprosy. Detailed comparisons between countries with very low leprosy incidence may help us to better understand the epidemiology of leprosy

Trends and measurement of HIV prevalence in northern Malawi.

BACKGROUND: Most data on HIV prevalence in Malawi come from antenatal clinic (ANC) surveillance and are, therefore, subject to bias. OBJECTIVES: HIV prevalence and risk factors were measured using population-based data to assess the accuracy of ANC surveillance and changes in prevalence and risk factors for HIV over time. METHODS: HIV prevalence was measured in 1988-1993 and 1998-2001 in community controls from case-control studies of mycobacterial disease in Karonga District, Malawi. ANC surveillance studies in the district began in 1999. RESULTS: Age and area-standardized HIV prevalence in women aged 15-49 years in the community was 3.9% in 1988-1990, 12.5% in 1991-1993 and 13.9% in 1998-2001. For men, HIV prevalence was 3.7%, 9.2% and 11.4% in the same periods. In 1988-1993, HIV positivity was associated with occupations other than farming, with increased schooling and being born outside Karonga District. In 1998-2001, non-farmers were still at higher risk but the other associations were not seen. The age- and area-adjusted HIV prevalence in the ANC in 1999-2001 was 9.2%. The underestimate can be explained largely by marriage and mobility. Reduced fertility in HIV-positive individuals was demonstrated in both ANC and community populations. A previously recommended parity-based adjustment gave an estimated female HIV prevalence of 15.0%. CONCLUSIONS: HIV prevalence has increased and continues to be higher in non-farmers. The increase is particularly marked in those with no education. ANC surveillance underestimated HIV prevalence in the female population in all but the youngest age group. Although there were differences in sociodemographic factors, a parity-based adjustment gave a reasonable estimate of female HIV prevalence

The contribution of multiple barriers to reproduction between edaphically divergent lineages in the Amazonian tree \u3cem\u3eProtium subserratum\u3c/em\u3e (Burseraceae)

Disentangling the strength and importance of barriers to reproduction that arise between diverging lineages is central to our understanding of species origin and maintenance. To date, the vast majority of studies investigating the importance of different barriers to reproduction in plants have focused on short-lived temperate taxa while studies of reproductive isolation in trees and tropical taxa are rare. Here, we systematically examine multiple barriers to reproduction in an Amazonian tree, Protium subserratum (Burseraceae) with diverging lineages of soil specialist ecotypes. Using observational, molecular, distributional, and experimental data, we aimed to quantify the contributions of individual prezygotic and postzygotic barriers including ecogeographic isolation, flowering phenology, pollinator assemblage, pollen adhesion, pollen germination, pollen tube growth, seed development, and hybrid fitness to total reproductive isolation between the ecotypes. We were able to identify five potential barriers to reproduction including ecogeographic isolation, phenological differences, differences in pollinator assemblages, differential pollen adhesion, and low levels of hybrid seed development. We demonstrate that ecogeographic isolation is a strong and that a combination of intrinsic and extrinsic prezygotic and postzygotic barriers may be acting to maintain near complete reproductive isolation between edaphically divergent populations of the tropical tree, P. subserratum