Lincoln H. Schmitt

Histamine sensitivity influences reactivity to allergens

The ability to mount an IgE response to allergens is a prerequisite for the development of positive allergen skin tests, and this is reflected to some extent by the observation that allergen-responsive subjects tend to have higher total serum IgE concentrations. To determine whether histamine sensitivity also contributes to allergen responsiveness, 893 subjects in a rural community were prick tested with 14 allergens and tenfold dilutions of histamine phosphate beginning at 1 mg/ml-1. IgE was measured in a subset of 400 subjects. Three-way contingency table analysis confirmed previous reports of an association between allergen responsiveness and IgE (p less than 0.001) and also demonstrated that allergen responsiveness is associated with sensitivity to histamine (p less than 0.001). This association is independent of IgE so that the additive effect of IgE and histamine sensitivity allows more nearly accurate prediction of allergen responsiveness than either measurement alone.

Variation in epinephrine and cortisol excretion rates associated with behavior in an Australian Aboriginal community.

Urinary epinephrine and cortisol hormone output in a remote Australian Aboriginal community was on average about twice as high in those individuals measured on a Thursday or Friday as those measured at the beginning of the next week (Monday or Tuesday). Diastolic blood pressure was about 6 mm Hg higher in the Thursday-Friday group, but the difference in mean systolic blood pressure between the day groups does not reach statistical significance. These physiological differences are associated with a marked dichotomy in behavior in the two time periods: on the first 2 days, virtually all adults were involved in intense gambling activity for large stakes, but this was not a feature of the latter period. This behavior pattern occurs on a regular weekly basis. If substantiated by longitudinal studies, this phenomenon may provide an additional link between human behavior and a poor health profile mediated via the physiological consequences of high stress hormone output.

A three-dimensional geometric morphometric analysis of variation in cranial size and shape in tammar wallaby (Macropus eugenii) populations

This study uses geometric morphometric techniques to examine cranial size and shape variation in nine isolated populations of the tammar wallaby (Macropus eugenii). A set of 36 three-dimensional landmarks were digitised on 143 tammar crania from two mainland and seven island populations. While there was no evidence of island dwarfism or gigantism, cranial size increased with both increasing island size and increasing latitude. As latitude increased, the palate narrowed relative to the nasal bones, cranial flexion and nasal height increased, and the zygomatic arches spread out laterally from the cranium. Overall, the anterior nasal aperture (nares) narrowed with increasing latitude. Mean shapes were calculated for each population, and pair-wise comparisons were made; most of these were significantly different. There was a clear tendency for island populations and those with greater geographic separation to show greater shape differentiation. Thus, regional and population differences in the cranial size and shape of tammar wallabies provide examples of selection, founder effect and random genetic drift.

Child size and household characteristics in rural Timor-Leste.

The main objective was to determine those characteristics of the family and household that affects child health (as measured by child size for age) in the rural Ossu area of Timor‐Leste.

The emergence of obesity among Australian Aboriginal children

Abstract Obesity is of significant and growing concern among Australian Aboriginal children, and is linked to patterns of child growth. The aim of this paper is to show diverse patterns of growth and obesity emergence among Australian Aboriginal children using historical anthropometric data. Child growth in height, weight and body mass index (BMI) is reanalysed for children aged 2 to 19 years in Australian Aboriginal communities spanning two distinct time periods (the 1950s and 1960s; and the 1990s and 2000s) and six different geographical locations: Yuendumu, Haast’s Bluff, Beswick, Kalumburu, Gerard, and Raukkan. Comparisons of stature and BMI between the earlier and later years of measurement were made, and the proportion of children classified as overweight or obese by the International Obesity Task Force criteria estimated, to allow international comparison. Aboriginal children in the 1990s and 2000s were heavier, with higher BMI than those in the 1950s and 1960s, differences in height being less marked. While no children were classified as overweight or obese in the earlier period, 15% of males and 3% of females were classified so in the later period. The data suggests that the period of onset of the epidemic of overweight and obesity among rural Australian Aboriginal children was likely to have been between the 1960s and 1980s.

Living in isolation: Ecological, demographic and genetic patterns in northern Australia's top marsupial predator on Koolan Island

Koolan Island supports an abundant population of the threatened northern quoll (Dasyurus hallucatus). We used a mark–release–recapture program that produced 2089 captures from 2009 to 2012 to examine demographic and genetic parameters in this insular population and compare to other localities. Every captured female was either lactating or carrying up to eight young over the breeding season, July–September. Unlike several other populations, males on Koolan Island can survive long after breeding, but never into a second breeding season. Females can survive and reproduce for two successive annual breeding seasons and occasionally survive to a third. There is marked sexual dimorphism but it is less pronounced, and both sexes are smaller than their mainland counterparts. Quolls were recorded moving over 4 km and apparent abundance was far higher on Koolan Island than the mainland. Genetic analyses of nuclear and mitochondrial markers demonstrate a distinctive signature. Koolan island has only 34% of the allelic richness of the entire species, and only 38% of the alleles in Kimberley mainland and near-shore island populations. There is no evidence of recent or long-term population decline. Kimberley island faunas have distinctive demographic and genetic profiles that should be appraised before considering translocations for conservation purposes.

The burrowing bettongs of Barrow Island: demographic and genetic insights into a threatened macropod

Abstract. Islands provide the last refuge for many Australian species that have succumbed to range contractions since European settlement. These species have heightened vulnerability when developments are planned for the islands. The burrowing bettong (Bettongia lesueur), a threatened macropod, was once widespread across Australia but now occurs naturally only on Barrow Island and two other Western Australian offshore islands. Here, we document the demographic, social and genetic characteristics of the Barrow Island population, using nuclear microsatellites, mtDNA and demographic parameters from 286 individuals trapped around 29 warrens. The Barrow Island population utilises complex warren systems scattered across the landscape and exhibits continuous breeding, even during extensive dry conditions. Males (759 g) were significantly heavier than females (735 g), with the latter reaching sexual maturity at ∼600 g. Warrens varied markedly in size and number of individuals, with 20% of females and 25% of males moving between nearby warrens. There were two deep mtDNA haplotype clades that coalesce around 298 000 years ago, indicating that this island population has maintained an effective population size that has permitted the retention of one marked feature of its preisolation genetic diversity. Dispersal and gene flow between warrens was severely constrained. Both mtDNA and 11 nuclear microsatellites showed a strong isolation by distance effect, with genetic differences between warrens increasing linearly with geographic separation. While this was marked in both sexes, it was stronger in females and consistent with shorter dispersal distances for females than for males. The trapping and genetic data are concordant, with between-warren sociality correlated with genetic similarity. Long-term conservation, management and translocation programs will benefit from cognisance of the strong fidelity to natal areas, as evidenced by both recapture data and genetic analyses.