45 research outputs found
Comparison of deferral rates using a computerized versus written blood donor questionnaire: a randomized, cross-over study [ISRCTN84429599]
BACKGROUND: Self-administered computer-assisted blood donor screening strategies may elicit more accurate responses and improve the screening process. METHODS: Randomized crossover trial comparing responses to questions on a computerized hand-held tool (HealthQuiz, or HQ), to responses on the standard written instrument (Donor Health Assessment Questionnaire, or DHAQ). Randomly selected donors at 133 blood donation clinics in the area of Hamilton, Canada participated from 1995 to 1996. Donors were randomized to complete either the HQ or the DHAQ first, followed by the other instrument. In addition to responses of 'yes' and 'no' on both questionnaires, the HQ provided a response option of 'not sure'. The primary outcome was the number of additional donors deferred by the HQ. RESULTS: A total of 1239 donors participated. Seventy-one potential donors were deferred as a result of responses to the questionnaires; 56.3% (40/71) were deferred by the DHAQ, and an additional 43.7% (31/71) were deferred due to risks identified by the HQ but not by the DHAQ. Fourteen donors self-deferred; 11 indicated on the HQ that they should not donate blood on that day but did not use the confidential self-exclusion option on the DHAQ, and three used the self-exclusion option on the DHAQ but did not indicate that they should not donate blood on the HQ. The HQ identified a blood contact or risk factor for HIV/AIDS or sexually transmitted infection that was not identified by the DHAQ in 0.1% to 2.7% of donors. CONCLUSION: A self-administered computerized questionnaire may increase risk reporting by blood donors
Estrogen Receptor Ī²-Selective Agonists Stimulate Calcium Oscillations in Human and Mouse Embryonic Stem Cell-Derived Neurons
Estrogens are used extensively to treat hot flashes in menopausal women. Some of the beneficial effects of estrogens in hormone therapy on the brain might be due to nongenomic effects in neurons such as the rapid stimulation of calcium oscillations. Most studies have examined the nongenomic effects of estrogen receptors (ER) in primary neurons or brain slices from the rodent brain. However, these cells can not be maintained continuously in culture because neurons are post-mitotic. Neurons derived from embryonic stem cells could be a potential continuous, cell-based model to study nongenomic actions of estrogens in neurons if they are responsive to estrogens after differentiation. In this study ER-subtype specific estrogens were used to examine the role of ERĪ± and ERĪ² on calcium oscillations in neurons derived from human (hES) and mouse embryonic stem cells. Unlike the undifferentiated hES cells the differentiated cells expressed neuronal markers, ERĪ², but not ERĪ±. The non-selective ER agonist 17Ī²-estradiol (E2) rapidly increased [Ca2+]i oscillations and synchronizations within a few minutes. No change in calcium oscillations was observed with the selective ERĪ± agonist 4,4ā²,4ā³-(4-Propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT). In contrast, the selective ERĪ² agonists, 2,3-bis(4-Hydroxyphenyl)-propionitrile (DPN), MF101, and 2-(3-fluoro-4-hydroxyphenyl)-7-vinyl-1,3 benzoxazol-5-ol (ERB-041; WAY-202041) stimulated calcium oscillations similar to E2. The ERĪ² agonists also increased calcium oscillations and phosphorylated PKC, AKT and ERK1/2 in neurons derived from mouse ES cells, which was inhibited by nifedipine demonstrating that ERĪ² activates L-type voltage gated calcium channels to regulate neuronal activity. Our results demonstrate that ERĪ² signaling regulates nongenomic pathways in neurons derived from ES cells, and suggest that these cells might be useful to study the nongenomic mechanisms of estrogenic compounds
Comparison of left ventricular mechanics in runners versus bodybuilders using speckle tracking echocardiography
Is 2D speckle tracking echocardiography useful for detecting and monitoring myocardial dysfunction in adult m.3243A>G carriers? ā a retrospective pilot study
Transcription, Epigenetics and Ameliorative Strategies in Huntingtonās Disease: a Genome-Wide Perspective
Recommended from our members
Tropical forest aboveāground productivity is maintained by nutrients cycled in litter
Publication status: PublishedFunder: Smithsonian Institution Postdoctoral FellowshipFunder: Drummond FundFunder: Gonville and Caius College, University of Cambridge; doi: http://dx.doi.org/10.13039/501100000622Funder: University of Cambridge; doi: http://dx.doi.org/10.13039/501100000735Funder: Wolfson College Alice Evans Memorial Fund, University of CambridgeFunder: Cambridge European TrustFunder: University of Cambridge Domestic Research StudentshipAbstract
Tropical forest productivity represents an important global carbon sink, but many tropical forests grow on infertile soils. Efficient nutrient cycling by litterfall has long been assumed to maintain tropical tree growth, but there is no direct evidence that the nutrients cycled in litterfall are essential for tropical forest productivity.
To test whether nutrient cycling by litterfall maintains tropical forest aboveāground productivity, we established largeāscale longāterm litter removal (Lā) and litter addition (L+) treatments in a mature lowland tropical forest. We hypothesised that the removal of nutrients in litter would reduce tree growth, survival and litter production in Lā plots. By contrast, the addition of nutrients in litter would enhance tree growth, survival and litter production in L+ plots. To test our hypotheses, we recorded tree growth and survival every 2āyears, and measured litterfall monthly during 17āyears of treatments.
Tree growth and litterfall declined over time in Lā plots, with consistently lower growth rates compared to controls after 8āyears, and lower litter production after 4āyears of treatments. By contrast, although litterfall was higher in the L+ plots relative to the controls, there was only a minor transient increase in tree growth immediately after the start of treatments. Tree survival declined over time in all treatments but was not affected by litter manipulation.
The longāterm decline in tree growth and litterfall in the Lā plots provides the first empirical evidence that nutrient cycling by litterfall plays a key role in maintaining aboveāground productivity in this tropical forest. By contrast, the transient increase in growth in the L+ plots can be attributed to the large inputs of nutrients with the addition of the entire litter standing crop at the start of treatments. The addition of nutrients in litter over the long term was nonetheless sufficient to enhance litter production, possibly by accelerating leaf turnover.
Synthesis: Efficient nutrient cycling by litterfall makes an important contribution to the annual nutrient requirements of mature tropical forest trees, compensating for infertile soils. Disturbances that disrupt this finely balanced cycle could therefore reduce biomass carbon sequestration in tropical forests.
</jats:p