Use of PIXE/PIGE for sequential Ca and F measurements in root carious model

The progress of caries has conventionally been evaluated by checking changes in mineral density using transverse microradiography (TMR). Recent advances have seen development of a new measurement system, using in-air micro proton induced X-ray/gamma-ray emission (PIXE/PIGE). PIXE/PIGE enables analysis of distributions and concentrations of multiple mineral elements in a carious lesion. The aim of this study was to evaluate the effectiveness of PIXE/PIGE for investigating the development of root caries. In summary, we successfully established a multi-elemental sequential measuring method using in-air micro-PIXE/PIGE to identify the dynamic distributions and concentrations of Ca and F in human root dentin. The PIXE/PIGE potentially offers a useful advantageous technique for studying carious development by using as a combination with conventional techniques such as TMR and Micro-computed tomography (µCT).

Inositol Hexakis Phosphate is the Seasonal Phosphorus Reservoir in the Deciduous Woody Plant Populus alba L

Seasonal recycling of nutrients is an important strategy for deciduous perennials. Deciduous perennials maintain and expand their nutrient pools by the autumn nutrient remobilization and the subsequent winter storage throughout their long life. Phosphorus (P), one of the most important elements in living organisms, is remobilized from senescing leaves during autumn in deciduous trees. However, it remains unknown how phosphate is stored over winter. Here we show that in poplar trees (Populus alba L.), organic phosphates are accumulated in twigs from late summer to winter, and that IP6 (myo-inositol-1,2,3,4,5,6-hexakis phosphate: phytic acid) is the primary storage form. IP6 was found in high concentrations in twigs during winter and quickly decreased in early spring. In parenchyma cells of winter twigs, P was associated with electron-dense structures, similar to globoids found in seeds of higher plants. Various other deciduous trees were also found to accumulate IP6 in twigs during winter. We conclude that IP6 is the primary storage form of P in poplar trees during winter, and that it may be a common strategy for seasonal P storage in deciduous woody plants.

Interactive effects of specific fine particulate matter compositions and airborne pollen on frequency of clinic visits for pollinosis in Fukuoka, Japan

BACKGROUND

Previous studies have revealed the interactive effects of airborne pollen and particulate matter on the daily consultations for pollinosis, but it is uncertain which compositions are responsible. This study aimed to investigate the interactive effects of specific PM_2.5 compositions and airborne pollen on the daily number of clinic visits for pollinosis in Fukuoka.

METHODS

We obtained daily data on pollen concentrations, PM_2.5 compositions, PM_2.5 mass, gaseous pollutants (SO₂, NO₂, CO, and O₃), and weather variables monitored in Fukuoka between February and April, 2002-2012. In total, 73,995 clinic visits for pollinosis were made at 10 clinics in Fukuoka Prefecture during the study period. A time-stratified case-crossover design was applied to examine the interactive effects. The concentrations of PM_2.5 and its compositions were stratified into low (<15th percentile), moderate (15th-85th percentile), and high (>85th percentile) levels, and the association between airborne pollen and daily clinic visits for pollinosis was analyzed within each level.

RESULTS

We found a significant interaction between specific PM_2.5 compositions and airborne pollen. Specifically, the odds ratio of daily clinic visits for pollinosis per interquartile increase in pollen concentration (39.8 grains/cm²) at the average cumulative lag of 0 and 2 days during high levels of non-sea-salt Ca²⁺ was 1.446 (95% CI: 1.323-1.581), compared to 1.075 (95% CI: 1.067-1.083) when only moderate levels were observed. This result remained significant when other air pollutants were incorporated into the model and was fairly persistent even when different percentile cut-off points were used. A similar interaction was found when we stratified the data according to non-sea-salt SO₄^2- levels. This finding differed from estimates made according to PM_2.5 and NO₃^- levels, which predicted that the effects of pollen were strongest in the lower levels.

CONCLUSIONS

Associations between airborne pollen and daily clinic visits for pollinosis could be enhanced by high levels of specific PM_2.5 compositions, especially non-sea-salt Ca²⁺.