Association of airborne particulate matter with pollen, fungal spores, and allergic symptoms in an arid urbanized area.

Studies focused on the seasonal distribution of pollen and spores in semiarid cities are scarce. At these sites, climate change potentiates the emission and transport of fine (PM10) to ultrafine particles (PM2.5), easily attached to pollen surfaces, causing allergen's release. This study examines the potential correlation of seasonal variations of pollen, fungal spores, PM10, and meteorological parameters with allergic reactions of 150 people living in a Sonoran desert city. We collected PM10, airborne pollen, and spores during a year. We also studied topsoil and road dust samples as potential PM-emission sources. We obtained dust-mineralogy, chemistry, and particle size attached to pollen by X-ray diffraction and scanning electron microscope. Results show that seasonal high PM-loading in the urban atmosphere coincides with aeroallergens promoting micro- to nanoparticles' attachment to pollen's surface. A collapsed membrane was observed in several samples after individual grains show the following maximum wall coverage: Poaceae 28%, Asteraceae 40%, Chenopodiaceae-Amaranthacea 29%, Fabaceae 18%. Most of the particles covering pollen's surface have a geogenic origin mixed with metals linked to traffic (bromide, chlorine, and antimony). Mineralogical, granulometric analysis, and main wind-direction show that two local soil-types are the main contributors to PM. A high frequency of positive sensitization to pollen with high particle loading was detected. These results suggest that climate-driven dust emissions may alter pollen and spore surfaces' physicochemical characteristics with the further consequences in their allergenic potential.

Brain auditory activation measured by near-infrared spectroscopy (NIRS) in neonates.

This study presents a new measure of the hemodynamic changes to an auditory stimulus in newborns. Nineteen newborns born at 28-41 wk and aged 1 to 49 d were studied in waking and/or sleeping state, for a median time of 4 min 40 s before, 2 min 40 s during, and 3 min 5 s after an acustic stimulus (tonal sweep of frequency increasing from 2 to 4 kHz, intensity 90 dB SPL) originating 5 cm from the external auditory meatus. The emitter and detector optodes were placed over the left or right temporal region, corresponding to T3 or T4 EEG electrodes. The concentration changes in cerebral chromophores Delta[HbO2], Delta[Hb] and Deltaoxidized-reduced cytochrome aa(3) were recorded every 5 s. Changes in cerebral blood volume were calculated from the changes in total Hb x 0.89/large vessel Hb concentration. Increased oxyhemoglobin, Delta[HbO2], total Hb, Delta[Hb (sum)], and cerebral blood volume, DeltaCBV, were found in 13/19 neonates, with the exception of a neonate who only had increased in Delta[Hb], Delta[Hb (sum)] and DeltaCBV. During the stimulation phase there was a significant increase in DeltaCBV (t test, p = 0.00006) in the responsive newborns from a mean value of 0.006 (+/-0.02) mL/100 g in the pretest phase to 0.09 (+/-0.06) mL/100 g during the auditory stimulus. After the test DeltaCBV decreased to 0.04 (+/-0.07) mL/100 g (t test, p = 0.01), so did Delta[Hb (sum)] (p = 0.02). Hemodynamic responses of the subjects who showed increases in Delta[Hb (sum)] and Delta[HbO(2)] were analyzed to study the Delta[Hb]. The responder subjects could be classified into two groups according to Delta[Hb] changes: 8/13 (61.5%) showed an increase of Delta[Hb] (pattern A), while 5/13 (38.4%) showed a decrease (pattern B) (t test, p = 0.03). These two patterns did not show differences related to Delta[HbO(2)] and Delta[Hb (sum)]. The DeltaCBV changes in nonresponders presented a decrease during the test phase (t test, p = 0.04). CBV did not return to pretest values, suggesting a fronto-temporal brain pathway for storing unusual sounds. The increase in CBV followed the local increase in oxyhemoglobin and total Hb concentrations due to a greater use of oxygen in the homolateral temporal cortex of the newborns.