Reference interval evaluation of high-sensitivity troponin T and N-terminal B-type natriuretic peptide in Vietnam and the US: The North South East West Trial.

BACKGROUND: Reference intervals of high-sensitivity troponin T (hs-cTnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) have been determined from Western populations. No data are available regarding expected values in Asian populations. METHODS: A total of 1157 age- and sex-matched healthy individuals (mean age, 41.2 years; 48.0% male) were prospectively enrolled from the US (n = 565) and Vietnam (n = 592). Blood samples were analyzed for hs-cTnT and NT-proBNP. Median values were determined for each country and compared in unadjusted analyses and in analyses adjusted for age, sex, body mass index, study site, race, and vital signs. RESULTS: Median hs-cTnT concentrations were slightly higher for individuals from the US than for those from Vietnam, but both were below the limit of detection (3.7 vs 3.0 ng/L, respectively; P = 0.03). More US participants had an hs-cTnT concentration above the limit of detection (57.2% vs 47.3%; P = 0.001), but the 99th percentile concentration was slightly higher for Asians (US 15.1 vs Vietnam 19.0 ng/L). Concentrations for >98% of both populations were below the standard hs-cTnT 99th percentile of 14.0 ng/L (P = 0.54). Median NT-proBNP concentrations were slightly higher for US participants compared with Vietnamese participants (28 vs 16 ng/L, respectively; P < 0.001). Following adjustment, differences in concentrations of NT-proBNP between healthy US and Vietnamese populations remained significant, whereas for hs-cTnT the differences were no longer significant. Inclusion of hs-cTnT values down to the limit of blank did not change the result. CONCLUSIONS: The differences in hs-cTnT and NT-proBNP between healthy individuals from the US and Vietnam are small. Previously derived reference intervals for both analytes may be applied in Asian populations.

Cryptic seedling herbivory by nocturnal introduced generalists impacts survival, performance of native and exotic plants.

Although much of the theory on the success of invasive species has been geared at escape from specialist enemies, the impact of introduced generalist invertebrate herbivores on both native and introduced plant species has been underappreciated. The role of nocturnal invertebrate herbivores in structuring plant communities has been examined extensively in Europe, but less so in North America. Many nocturnal generalists (slugs, snails, and earwigs) have been introduced to North America, and 96% of herbivores found during a night census at our California Central Valley site were introduced generalists. We explored the role of these herbivores in the distribution, survivorship, and growth of 12 native and introduced plant species from six families. We predicted that introduced species sharing an evolutionary history with these generalists might be less vulnerable than native plant species. We quantified plant and herbivore abundances within our heterogeneous site and also established herbivore removal experiments in 160 plots spanning the gamut of microhabitats. As 18 collaborators, we checked 2000 seedling sites every day for three weeks to assess nocturnal seedling predation. Laboratory feeding trials allowed us to quantify the palatability of plant species to the two dominant nocturnal herbivores at the site (slugs and earwigs) and allowed us to account for herbivore microhabitat preferences when analyzing attack rates on seedlings. The relationship between local slug abundance and percent cover of five common plant taxa at the field site was significantly negatively associated with the mean palatability of these taxa to slugs in laboratory trials. Moreover, seedling mortality of 12 species in open-field plots was positively correlated with mean palatability of these taxa to both slugs and earwigs in laboratory trials. Counter to expectations, seedlings of native species were neither more vulnerable nor more palatable to nocturnal generalists than those of introduced species. Growth comparison of plants within and outside herbivore exclosures also revealed no differences between native and introduced plant species, despite large impacts of herbivores on growth. Cryptic nocturnal predation on seedlings was common and had large effects on plant establishment at our site. Without intensive monitoring, such predation could easily be misconstrued as poor seedling emergence.