[Characteristics and Sources of Microbial Aerosols in Urban and Mountainous Areas in Autumn and Winter in Xi'an, China].

To explore the bioaerosol composition characteristics and sources in urban areas and mountains, three sample sites were selected in urban (urban, suburban) and southern mountainous areas in Xi'an, and air, soil, and leaf samples were simultaneously collected. The fungi and bacteria community structures at different sampling sites were analyzed through a high-throughput sequencing method, and their spatio-temporal variations were also examined. Moreover, a source track technique was used to identify the source of microorganisms in the air. The results showed that the fungi and bacteria at different sampling sites were significantly different, indicating that the geographical location has a significant influence on the community structure of microorganisms in the air. In winter, more potential fungal pathogens and bacterial pathogens were detected in urban areas with high relative abundance and diversity. In addition, the results showed that the main local source of fungi and bacteria was the leaf surface, of which the contribution rate of bacteria in the air fine particles was up to (55±30)%. This study can provide a scientific basis for understanding the characteristics of microbial pollution in the atmosphere, and for air environment quality evaluation and disease prevention in China.

Association of orthostatic hypotension with Parkinson's disease: a meta-analysis.

OBJECTIVE: Orthostatic hypotension (OH) is a common non-motor sign of Parkinson's disease (PD). Several epidemiological studies have estimated the association between OH and PD with controversial results. Here, a meta-analysis was conducted to evaluate the association between them. METHODS: PubMed, Embase, Web of Science, CNKI (Chinese National Knowledge Infrastructure), VIP (Database of Chinese Scientific and Technical Periodicals), and Wanfang databases were searched for eligible publications from October 2003 to December 2017. Prevalence numbers from studies were pooled using a non-linear random-effects meta-analysis. Random effect model was used to calculate the pooled odds ratio (OR) with 95% confidence intervals (CIs) from individual studies. Publication bias was estimated by Egger's test, Begg's test, and the funnel plot. RESULTS: Nineteen studies involving 1620 PD patients and 898 healthy controls were included in this meta-analysis. The pooled estimate of the prevalence of OH in PD was 27.7% compared with 7.9% of that in control. The pooled OR of OH with PD was 4.343 (95% CI 3.323-5.676) with a low heterogeneity (I2 = 12.5%, Pheterogeneity = 0.301). CONCLUSION: In the present meta-analysis, the pooled OR of OH with PD was 4.343 (95% CI 3.323-5.676) with a low heterogeneity, which showed a significant association between OH and increased risk of PD.

Temporal-spatial variations of fungal composition in PM2.5 and source tracking of airborne fungi in mountainous and urban regions.

Fungi are ubiquitous in air and their composition is potentially important for human health. Exposure to fungal allergens has been considered as a significant risk factor due to the prevalence and severity of asthma in humans. However, temporal-spatial variations and potential sources of airborne fungi aerosol have been poorly understood. In this study, 48 PM2.5 samples were collected at two sampling sites in Xi'an from April 2018 to January 2019. High-throughput sequencing technology was used to determine the diversity and abundance of fungal composition in all samples. Microbial samples were also collected from leaf-surface and soil to identify the potential sources of fungal aerosols. Results showed that the species richness of fungi in summer and autumn inclined to be higher than that in spring and winter in mountainous and urban regions. Airborne fungal species richness and diversity at Mt. Qinling sampling site were significantly higher compared to Yanta urban sampling site, except in winter. These variations in fungal composition were significantly related to season and location. The influence of atmospheric pollutants (PM2.5, ozone, sulfur dioxide and carbon monoxide) on the richness and diversity of airborne fungal composition was higher than meteorological factors (temperature, relative humidity and wind speed). Moreover, it was observed that the leaf-surface was the primary local source of airborne fungi during all seasons at both sampling sites. Back trajectories arriving at both sampling sites showed that a considerable part of airborne fungi might have come from other regions by medium or long-range airflow. This study will provide an important reference for studying the source and temporal-spatial variations of fungal aerosols and further provide basic background data for human health exposure assessment.

Characteristics of airborne opportunistic pathogenic bacteria during autumn and winter in Xi'an, China.

Bacteria are ubiquitous throughout the earth's lower atmosphere. Bacteria, especially pathogenic bacteria, play an important role in human health. The diversity, composition, and dynamics of airborne bacteria has been widely studied; however, the characteristics of pathogenic bacteria remain poorly understood. In this study, a high throughput sequencing method was used to explore the airborne opportunistic pathogenic bacteria during autumn and winter in Xi'an, China. An aggregated boosted tree (ABT) was developed to determine the relative influence of environmental factors on the proportions of opportunistic pathogenic bacteria. Results showed that significantly more opportunistic pathogenic bacteria were found in winter than in autumn, and more opportunistic pathogenic bacteria were found in fine particulate matters (<2.5 µm) than in PM10 (<10 µm). However, the composition of opportunistic pathogenic bacteria varied in autumn and winter. PM was the main factor affecting the proportions of opportunistic pathogenic bacteria, and air contaminants (PM, sulfur dioxide, nitrogen oxide, carbon monoxide, and ozone) influenced the proportion of opportunistic pathogenic bacteria more than meteorological factors (relative humidity, temperature, and wind speed). Different factors may be responsible for the variances in opportunistic pathogenic bacterial communities in different seasons. This study may provide a reference to support the control of pathogenic bacteria in urban environments during haze events.