ED-XRF: a promising method for accurate and rapid quantification of metals in a bacterial matrix.

ABSTRACTThe remediation of metal-polluted water using bacterial biofilms is a promising technology. In order to help its development, the present study aims to evaluate the feasibility to utilize XRF spectrometry for accurate and rapid measurement of metal concentrations in bacterial biofilms used in treatment plants. For that purpose, an ED-XRF spectrometer was used to measure Cd, Cu, Fe, Mn, Ni and Zn concentrations within a matrix of marine bacteria Pseudomonas fluorescens BA3SM1 and its metabolites. Contaminated and control cultures of the strain BA3SM1 were dried and crushed, then analysed by ED-XRF. The LOD value of the analysed metals was between 2.08 and 10.5 µg g-1. Metal concentrations were also measured by ICP-AES or ICP-MS to support ED-XRF results. The two techniques showed a good linear correlation with a slope of at least 0.949 and R2 of at least 0.985. These results confirm the possibility to measure metal contents by ED-XRF in bacterial matrices.

Marine aggregates in North Atlantic coast: Microbial characteristics and potential interactions with farmed Atlantic salmon (Salmo salar).

Microbial contamination of aggregates collected near an Atlantic salmon farm, in the Cherbourg roadstead, was followed monthly over one year to study the dynamics of Vibrio spp. and explore their impact on farmed fish. Salmon state of health was followed through blood and histopathological analyses. Vibrio were systematically found in aggregates with particularly high concentration in August. The Splendidus clade was strongly dominant in aggregates as well as in gills, and an increase in Vibrio diversity was observed in summer and autumn. Results did not demonstrate that aggregates directly impact the bacterial community of gills, but they suggested an aggregates-gills interaction. Gill contamination was correlated with water temperature and probably impacted by amoebae. Vibrio renipiscarius and Vibrio toranzoniae were isolated in North Atlantic for the first time. A better understanding of the interaction between marine aggregates, Vibrio spp. and fish is essential to improve salmon cage farming.

Analysis of HIV testing refusal among patients aged less than 21 years in the Pediatric Emergency Department.

HIV testing in the Pediatric Emergency Department (PED) is a novel concept as adolescents, and young adults, use the PED as point of care or first point of contact with the health care system. Our objective was to study the HIV nontesting data and factors that influenced testing decision among patients receiving care in our PED. We designed a survey that inquired about testing acceptance, reasons for rejection, satisfaction with testing conditions, and understanding of the consequence of HIV test results. We approached 500 patients across all shifts in the PED; for analysis, categorical variables were created using demographic data (race, age, ethnicity, marital status, level of education). Forward conditional binary logistic regression was used to explore the effect of various independent predictors on HIV testing rejection with the strength of association measured with adjusted odds ratio (OR), and their 95% CIs. We conducted model fitting by plotting residuals, Hosmer and Lemeshow test statistic, and area under the curve completed using predicted probabilities. We used SPSS Version 25™, Microsoft Excel 2016™ for data preparation and analysis. Of the 500 patients approached, 423 (84.6%) completed the survey, median (interquartile) age of survey participants was 19 (17-20) years, 158 (37.4%) rejected HIV testing, 284 (67.1%) were older than 18 years of age, 200 (47.3%) were males, 154 (36.4%) were white, and 127 (30%) were of Hispanic origin. The most common reason for rejecting HIV was low risk perception declared by 79 (50%) respondents. In multivariate analysis, age <18 years (OR, 3.5; 95% CI, 2.3-5.5, P<0.00) and being Hispanic (OR, 2.5; 95% CI, 1.6-3.8, P<0.00) were significant predictors for respondent nontesting. Hosmer and Lemeshow test was not significant, P=0.42, and area under the curve was 0.67 (95% CI, 0.61-0.76). Respondents, <18 years were more likely to reject HIV testing because of low perception of risk. Program addressing risk perception which emphasizes safe health practices should be developed to reduce HIV transmission.

A fracture, a family, legal entanglement, expensive investigation, and a familiar disease.

Osteogenesis imperfecta can be commonly mistaken for child abuse because of similar pattern of injuries. AA is a 3-week-old baby who presented to our emergency department with excessive crying. Skeletal survey revealed subacute spiral fracture of the right humerus, right posterior eighth and ninth ribs, acute fracture of the left femur, bowing of tibia and femur, and osteopenia. Subsequent geneticist examination and genetic testing noted blue sclera and heterozygosity for a variant of COL1A gene.

Toxicological effects of CdSe nanocrystals on the marine diatom Phaeodactylum tricornutum: The first mass spectrometry-based proteomic approach.

In the marine environment, benthic diatoms from estuarine and coastal sediments are among the first targets of nanoparticle pollution whose potential toxicity on marine organisms is still largely unknown. It is therefore relevant to improve our knowledge of interactions between these new pollutants and microalgae, the key players in the control of marine resources. In this study, the response of P. tricornutum to CdSe nanocrystals (CdSe NPs) of 5 nm (NP5) and 12 nm (NP12) in diameter was evaluated through microscopic, physiological, biochemical and proteomic approaches. NP5 and NP12 affected cell growth but oxygen production was only slightly decreased by NP5 after 1-d incubation time. In our experimental conditions, a high CdSe NP dissolution was observed during the first day of culture, leading to Cd bioaccumulation and oxidative stress, particularly with NP12. However, after a 7-day incubation time, proteomic analysis highlighted that P. tricornutum responded to CdSe NP toxicity by regulating numerous proteins involved in protection against oxidative stress, cellular redox homeostasis, Ca2+ regulation and signalling, S-nitrosylation and S-glutathionylation processes and cell damage repair. These proteome changes allowed algae cells to regulate their intracellular ROS level in contaminated cultures. P. tricornutum was also capable to control its intracellular Cd concentration at a sufficiently low level to preserve its growth. To our knowledge, this is the first work allowing the identification of proteins differentially expressed by P. tricornutum subjected to NPs and thus the understanding of some molecular pathways involved in its cellular response to nanoparticles. SIGNIFICANCE: The microalgae play a key role in the control of marine resources. Moreover, they produce 50% of the atmospheric oxygen. CdSe NPs are extensively used in the industry of renewable energies and it is regrettably expected that these pollutants will sometime soon appear in the marine environment through surface runoff, urban effluents and rivers. Since estuarine and coastal sediments concentrate pollutants, benthic microalgae which live in superficial sediments will be among the first targets of nanoparticle pollution. Thus, it is relevant to improve our knowledge of interactions between diatoms and nanoparticles. Proteomics is a powerful tool for understanding the molecular mechanisms triggered by nanoparticle exposure, and our study is the first one to use this tool to identify proteins differentially expressed by P. tricornutum subjected to CdSe nanocrystals. This work is fundamental to improve our knowledge about the defence mechanisms developed by algae cells to counteract damage caused by CdSe NPs.