Intercomparison of desert dust optical depth from satellite measurements

This work provides a comparison of satellite retrievalsof Saharan desert dust aerosol optical depth (AOD)during a strong dust event through March 2006. In this event,a large dust plume was transported over desert, vegetated,and ocean surfaces. The aim is to identify the differencesbetween current datasets. The satellite instruments consideredare AATSR, AIRS, MERIS, MISR, MODIS, OMI,POLDER, and SEVIRI. An interesting aspect is that the differentalgorithms make use of different instrument characteristicsto obtain retrievals over bright surfaces. These includemulti-angle approaches (MISR, AATSR), polarisationmeasurements (POLDER), single-view approaches using solarwavelengths (OMI, MODIS), and the thermal infraredspectral region (SEVIRI, AIRS). Differences between instruments,together with the comparison of different retrievalalgorithms applied to measurements from the same instrument,provide a unique insight into the performance andcharacteristics of the various techniques employed. As wellas the intercomparison between different satellite products,the AODs have also been compared to co-located AERONETdata. Despite the fact that the agreement between satellite andAERONET AODs is reasonably good for all of the datasets,there are significant differences between them when comparedto each other, especially over land. These differencesare partially due to differences in the algorithms, such as assumptionsabout aerosol model and surface properties. However,in this comparison of spatially and temporally averageddata, it is important to note that differences in sampling, relatedto the actual footprint of each instrument on the heterogeneousaerosol field, cloud identification and the qualitycontrol flags of each dataset can be an important issue

Oral bacterial load in autoimmune liver diseases: possible role or coincidence?

Background and aims: Several factors seem be involved in the pathogenesis of autoimmune liver disease (ALD), such as bacteria or bacterial components. Some studies highlighted the role of an oral bacterium, P. gingivalis, in the pathogenesis of rheumatoid arthritis and in the induction of NASH. We evaluated if there was a correlation between oral bacteria and some features of ALD. Methods: We analyzed 50 patients with ALD, 22 with autoimmune hepatitis (AIH) and 28 with primary biliary cirrhosis (PBC), 94% females, median age 61 years, median disease duration 7.5 years, 18% with cirrhosis, 66% responders to treatment, 40% with concomitant autoimmune diseases, and 46 health controls matched for sex and age. Patients and controls were subjected to cytobrush of the tongue. Exclusion criteria were antibiotic use in the previous week, mouthwash use on the day of inclusion. The study was conducted with the local ethics committee approval and informed consent was obtained from all subjects. Bacterial DNA (BD) obtained from the tongue biofilm was quantified using a computer RNA-DNA and expressed as ug/ml of sample.For each analysis, three distinct biological replicas were done, and quantitative data were expressed as mean ± SD. Results: BD amount was greater in ALD than in controls (1834.10 vs. 881.75, p < 0.0001). There was no correlation between BD amount and age, disease duration, histological findings and biochemical parameters, except for alkaline phosphatase (p = 0.05). The presence of cirrhosis, response to therapy and the immunosuppressive drug use did not affect BD amount. Finally, patients with concomitant autoimmune diseases had a greater BD amount than the other (2053.54 vs. 1687.60) but without significance (p = 0.57). Conclusion: Our study showed an unspecified role of oral bacteria in patients with autoimmune liver diseases. Further analysis will be needed to assess if there are differences in the microbial population