Impact of oxytetracycline exposure on the digestive system microbiota of Daphnia magna.

Antibiotics are used to treat serious illness, but may also be used extraneously or as a preventative measure in many farm animals. This usage increases the potential for unintentional exposure to a variety of organisms. When antibiotics enter aquatic environments, Daphnia magna are especially vulnerable as they filter-feed in freshwater environments. Oxytetracycline (OTC) is a commonly-used broad-spectrum antibiotic used to treat a variety of mammalian diseases. In this study, the impact of OTC on D. magna mortality and gut biota were studied using both cultivation and sequencing-based approaches. Mortality rates were extremely low with the LD50 >2,000ppm. However, OTC impacted abundance and species diversity of intestinal microorganisms in the gut of the D. magna in abundance as well as species diversity. In control organisms, Pseudomonas putida and Aeromonas hydrophila were both present while only P. putida was found in OTC-exposed organisms. Disruption of the intestinal biota in D. magna could have implications on long-term survival, energy expenditure, and reproduction.

School nurses and children with diabetes: a descriptive study.

BACKGROUND: Managing diabetes in children is complex. The aims of this descriptive study were to describe the care provided to children with diabetes by school nurses using case management, to identify differences in care on the basis of the workload of the nurse and the age of the child, to explore the role of the nurse in responding to emergencies, and to describe the relationship between case management and quality of life. METHODS: School nurses completed an expanded health assessment. Individualized goals were established and interventions were provided on the basis of a protocol. Quantitative and qualitative data for children enrolled during the 2009-2010 academic year were analyzed. RESULTS: Eighty-six children were enrolled. The most common goals were related to establishing a safe school environment. Interventions varied depending on the workload of the nurse and the age of the child. Nurses assigned to 1-2 schools provided more intervention days (mean, 40.3 days) than did nurses assigned to 3-4 schools (mean, 24.4 days) (P < .05), particularly in the area of direct care. A total of 25 students experienced an emergency at school that initiated a cascade of events involving the parent (in 100% of cases), the teacher (in 96%), management of hyperglycemia (in 100%), and/or management of hypoglycemia (in 96%). For teens, case management improved quality of life, particularly the ability to communicate with health professionals. LIMITATIONS: The sample was small, and there was no comparison group. CONCLUSIONS: School nurses are effective in using case management to enhance the health and well-being of children with diabetes. This study should be replicated with a larger sample, a comparison group, and the inclusion of clinical outcomes.

Behavioral and physiological changes in Daphnia magna when exposed to nanoparticle suspensions (titanium dioxide, nano-C60, and C60HxC70Hx).

Little is known aboutthe impact manufactured nanoparticles will have on aquatic organisms. Previously, we demonstrated that toxicity differs with nanoparticle type and preparation and observed behavioral changes upon exposure to the more lethal nanoparticle suspensions. In this experiment, we quantified these behavioral and physiological responses of Daphnia magna at sublethal nanoparticle concentrations. Titanium dioxide (TiO2) and fullerenes (nano-C60) were chosen for their potential use in technology. Other studies suggest that addition of functional groups to particles can affect their toxicity to cell cultures, but it is unknown if the same is true at the whole organism level. Therefore, a fullerene derivative, C60HxC70Hx, was also used to examine how functional groups affect Daphnia response. Using a high-speed camera, we quantified several behavior and physiological parameters including hopping frequency, feeding appendage and postabdominal curling movement, and heart rate. Nano-C60 was the only suspension to cause a significant change in heart rate. Exposure to both nano-C60 and C60HxC70Hx suspensions caused hopping frequency and appendage movement to increase. These results are associated with increased risk of predation and reproductive decline. They indicate that certain nanoparticle types may have impacts on population and food web dynamics in aquatic systems.

Daphnia magna mortality when exposed to titanium dioxide and fullerene (C60) nanoparticles.

Nanoparticles (1-100 nm) comprise the latest technological advances designed to do everything from absorb environmental toxins to deliver drugs to a target organ. Recently, however, they have come under scrutiny for the potential to cause environmental damage. Because compounds in this miniature size range have chemical properties that differ from those of their larger counterparts, nanoparticles deserve special attention. Our main objective was to assess the potential impact that nanoparticles may have on release into aquatic environments. We prepared titanium dioxide (TiO2) and fullerene (C60) nanoparticles by filtration in tetrahydrofuran or by sonication. Daphnia magna were exposed to the four solutions using U.S. Environmental Protection Agency 48-h acute toxicity tests. Images of the particle solutions were recorded using transmission-electron microscopy, and the median lethal concentration, lowest-observable-effect concentration, and no-observable-effect concentration were determined. Exposure to filtered C60 and filtered TiO2 caused an increase in mortality with an increase in concentration, whereas fullerenes show higher levels of toxicity at lower concentrations. Exposure to the sonicated solutions caused varied mortality. Understanding the potential impacts of nanoparticles will help to identify the most appropriate nanotechnology to preserve the aquatic environment while advancing medical and environmental technology.