When significance becomes insignificant: Effect sizes and their uncertainties in Bayesian and frequentist frameworks as an alternative approach when analyzing ecotoxicological data

Microbial community history and leaf species shape bottom-up effects in a freshwater shredding amphipod

Arable land use and the associated application of agrochemicals can affect local freshwater communities with consequences for the entire ecosystem. For instance, the structure and function of leaf-associated microbial communities can be affected by pesticides, such as fungicides. Additionally, the leaf species on which these microbial communities grow reflects another environmental filter for community structure. These factors and their interaction may jointly modify leaves' nutritional quality for higher trophic levels. To test this assumption, we studied the structure of leaf-associated microbial communities with distinct exposure histories (pristine [P] vs vineyard run off [V]) colonising two leaf species (black alder, European beech, and a mixture thereof). By offering these differently colonised leaves as food to males and females of the leaf-shredding amphipod Gammarus fossarum (Crustacea; Amphipoda) we assessed for potential bottom-up effects. The growth rate, feeding rate, faeces production and neutral lipid fatty acid profile of the amphipod served as response variable in a 2 × 3 × 2-factorial test design over 21d. A clear separation of community history (P vs V), leaf species and an interaction between the two factors was observed for the leaf-associated aquatic hyphomycete (i.e., fungal) community. Sensitive fungal species were reduced by up to 70 % in the V- compared to P-community. Gammarus' growth rate, feeding rate and faeces production were affected by the factor leaf species. Growth was negatively affected when Gammarus were fed with beech leaves only, whereas the impact of alder and the mixture of both leaf species was sex-specific. Overall, this study highlights that leaf species identity had a more substantial impact on gammarids relative to the microbial community itself. Furthermore, the sex-specificity of the observed effects (excluding fatty acid profile, which was only measured for male) questions the procedure of earlier studies, that is using either only one sex or not being able to differentiate between males and females. However, these results need additional verification to support a reliable extrapolation.

What was the Epidemiology and Global Burden of Disease of Hip Fractures From 1990 to 2019? Results From and Additional Analysis of the Global Burden of Disease Study 2019

BACKGROUND

Hip fractures are associated with a high risk of death; among those who survive a hip fracture, many experience substantial decreases in quality of life. A comprehensive understanding of the epidemiology and burden of hip fractures by country, age, gender, and sociodemographic factors would provide valuable information for healthcare policymaking and clinical practice. The Global Burden of Disease (GBD) study 2019 was a global-level study estimating the burden of 369 diseases and injuries in 204 countries and territories. An exploration and additional analysis of the GBD 2019 would provide a clearer picture of the incidence and burden of hip fractures.

QUESTIONS/PURPOSES

Using data from the GBD 2019, we asked, (1) What are the global, regional, and national incidences of hip fractures, and how did they change over a recent 30-year span? (2) What is the global, regional, and national burden of hip fractures in terms of years lived with disability, and how did it change over that same period? (3) What is the leading cause of hip fractures? (4) How did the incidence and years lived with disability of patients with hip fractures change with age, gender, and sociodemographic factors?

METHODS

This was a cross-sectional study. Participant data were obtained from the GBD 2019 ( http://ghdx.healthdata.org/gbd-results-tool ). The GBD study is managed by the WHO, coordinated by the Institute of Health Metrics and Evaluation, and funded by the Bill and Melinda Gates Foundation. It estimates the burden of disease and injury for 204 countries by age, gender, and sociodemographic factors, and can serve as a valuable reference for health policymaking. All estimates and their 95% uncertainty interval (UI) were produced using DisMod-MR 2.1, a Bayesian meta-regression tool in the GBD 2019. In this study, we directly pulled the age-standardized incidence rate and years lived with disability rate of hip fractures by location, age, gender, and cause from the GBD 2019. Based on these data, we analyzed the association between the incidence rate and latitude of each country. Then, we calculated the estimated annual percentage change to represent trends from 1990 to 2019. We also used the Spearman rank-order correlation analysis to determine the correlation between the incidence or burden of hip fractures and the sociodemographic index, a composite index of the income per capita, average years of educational attainment, and fertility rates in a country.

RESULTS

Globally, hip fracture incidences were estimated to be 14.2 million (95% UI 11.1 to 18.1), and the associated years lived with disability were 2.9 million (95% UI 2.0 to 4.0) in 2019, with an incidence of 182 (95% UI 142 to 231) and 37 (95% UI 25 to 50) per 100,000, respectively. A strong, positive correlation was observed between the incidence rate and the latitude of each country (rho = 0.65; p < 0.001). From 1990 to 2019, the global incidence rate for both genders remained unchanged (estimated annual percentage change 0.01 [95% confidence interval -0.08 to 0.11]), but was slightly increased in men (estimated annual percentage change 0.11 [95% CI 0.01 to 0.2]). The years lived with disability rate decreased slightly (estimated annual percentage change 0.66 [95% CI -0.73 to -0.6]). These rates were standardized by age. Falls were the leading cause of hip fractures, accounting for 66% of all patients and 55% of the total years lived with disability. The incidence of hip fractures was tightly and positively correlated with the sociodemographic index (rho 0.624; p < 0.001), while the years lived with disability rate was slightly negatively correlated (rho -0.247; p < 0.001). Most hip fractures occurred in people older than 70 years, and women had higher incidence rate (189.7 [95% UI 144.2 to 247.2] versus 166.2 [95% UI 133.2 to 205.8] per 100,000) and years lived with disability (38.4 [95% UI 26.9 to 51.6] versus 33.7 [95% UI 23.1 to 45.5] per 100,000) than men.

CONCLUSION

Hip fractures are common, devastating to patients, and economically burdensome to healthcare systems globally, with falls being the leading cause. The age-standardized incidence rate has slightly increased in men. Many low-latitude countries have lower incidences, possibly because of prolonged sunlight exposure. Policies should be directed to promoting public health education about maintaining bone-protective lifestyles, enhancing the knowledge of osteoporosis management in young resident physicians and those in practice, increasing the awareness of osteoporosis screening and treatment in men, and developing more effective antiosteoporosis drugs for clinical use.

LEVEL OF EVIDENCE

Level III, prognostic study.

Multibiomarker responses to polycyclic aromatic hydrocarbons and microplastics in thumbprint emperor Lethrinus harak from a South Pacific locally managed marine area

To determine the baseline threat of microplastics and polycyclic aromatic hydrocarbons (PAHs) in an important seafood fish from Vueti Navakavu locally managed marine area, a multibiomarker risk assessment was conducted on the thumbprint emperor fish Lethrinus harak. Condition factor, a measure of relative general health condition of fish, was significantly lower in samples from the wet season compared to the dry season but no significant differences were observed for hepatosomatic index, a measure of relative stored energy/nutrition, between seasonal groups. PAHs levels of four metabolites in emperor fish from Fiji waters are reported here for the first time; seasonal groups showed no significant differences, but all samples presented levels of biliary PAHs. Each specimen also contained at least one microplastic in its gastrointestinal system; fibres were the predominant form-type and ingestion levels showed that more than 80% of fragment sizes were below 1.0 mm. Biochemical responses were observed for ethoxyresorufin-O-deethylase and glutathione S-transferase biotransformation activity, oxidative stress (glutathione peroxidase and glutathione reductase activity; lipid peroxidation) and genotoxicity (micronuclei assay). Though there were no statistically significant differences found, there were biological significances that were important to note; relatively low levels of pollutant exposure and low levels of biochemical responses showed enzymes response in thumbprint emperor were as expected to their roles in the body. In this multibiomarker approach, the observation of pollutants presence and histopathological injuries are considered biologically relevant from a toxicological perspective and serve as a baseline for future pollution studies in seafood fishes in Fiji, with site differences and the inclusion of fish species comparison. We recommend adopting a suite of biomarkers in future regional biomonitoring studies to develop holistic baseline information for other marine settings in Fiji and other Pacific Island countries.

Measuring mutagenicity in ecotoxicology: A case study of Cd exposure in Chironomus riparius

Existing mutagenicity tests for metazoans lack the direct observation of enhanced germline mutation rates after exposure to anthropogenic substances, therefore being inefficient. Cadmium (Cd) is a metal described as a mutagen in mammalian cells and listed as a group 1 carcinogenic and mutagenic substance. But Cd mutagenesis mechanism is not yet clear. Therefore, in the present study, we propose a method coupling short-term mutation accumulation (MA) lines with subsequent whole genome sequencing (WGS) and a dedicated data analysis pipeline to investigate if chronic Cd exposure on Chironomus riparius can alter the rate at which de novo point mutations appear. Results show that Cd exposure did not affect the basal germline mutation rate nor the mutational spectrum in C. riparius, thereby arguing that exposed organisms might experience a range of other toxic effects before any mutagenic effect may occur. We show that it is possible to establish a practical and easily implemented pipeline to rapidly detect germ cell mutagens in a metazoan test organism. Furthermore, our data implicate that it is questionable to transfer mutagenicity assessments based on in vitro methods to complex metazoans.

Magnetic Emissions from Brake Wear are the Major Source of Airborne Particulate Matter Bioaccumulated by Lichens Exposed in Milan (Italy)

The concentration of selected trace elements and the magnetic properties of samples of the lichen Evernia prunastri exposed for 3 months in Milan (Italy) were investigated to test if magnetic properties can be used as a proxy for the bioaccumulation of chemical elements in airborne particulate matter. Magnetic analysis showed intense properties driven by magnetite-like minerals, leading to significant correlations between magnetic susceptibility and the concentration of Fe, Cr, Cu, and Sb. Selected magnetic particles were characterized by Scanning Electron Microscope and Energy Dispersion System microanalyses, and their composition, morphology and grain size supported their anthropogenic, non-exhaust origin. The overall combination of chemical, morphoscopic and magnetic analyses strongly suggested that brake abrasion from vehicles is the main source of the airborne particles accumulated by lichens. It is concluded that magnetic susceptibility is an excellent parameter for a simple, rapid and cost-effective characterization of atmospheric trace metal pollution using lichens.

Bayesian multilevel model of micro RNA levels in ovarian-cancer and healthy subjects

In transcriptomics, micro RNAs (miRNAs) has gained much interest especially as potential disease indicators. However, apart from holding a great promise related to their clinical application, a lot of inconsistent results have been published. Our aim was to compare the miRNA expression levels in ovarian cancer and healthy subjects using the Bayesian multilevel model and to assess their potential usefulness in diagnosis. We have analyzed a case-control observational data on expression profiling of 49 preselected miRNA-based ovarian cancer indicators in 119 controls and 59 patients. A Bayesian multilevel model was used to characterize the effect of disease on miRNA levels controlling for differences in age and body weight. The difference between the miRNA level and health status of the patient on the scale of the data variability were discussed in the context of their potential usefulness in diagnosis. Additionally, the cross-validated area under the ROC curve (AUC) was used to assess the expected out-of-sample discrimination index of a different sets of miRNAs. The proposed model allowed us to describe the set of miRNA levels in patients and controls. Three highly correlated miRNAs: miR-101-3p, miR-142-5p, miR-148a-3p rank the highest with almost identical effect sizes that ranges from 0.45 to 1.0. For those miRNAs the credible interval for AUC ranged from 0.63 to 0.67 indicating their limited discrimination potential. A little benefit in adding information from other miRNAs was observed. There were several miRNAs in the dataset (miR-604, hsa-miR-221-5p) for which inferences were uncertain. For those miRNAs more experimental effort is needed to fully assess their effect in the context of new hits discovery and usefulness as disease indicators. The proposed multilevel Bayesian model can be used to characterize the panel of miRNA profile and to assess the difference in expression levels between healthy and cancer individuals.

Blinded by the light: Increased chlorophyll fluorescence of herbicide-exposed periphyton masks unfavorable structural responses during exposure and recovery

In surface waters within agricultural catchments, periphyton - i.e., biofilms containing algae, heterotrophs, and associated detritus - is subjected to multiple stressors including herbicides. Although herbicide effects on periphyton are frequently studied, the focus has been on photosynthesis-inhibiting herbicides while other modes of toxic action have received little attention. Against this background, a 21-days-lasting bioassay was conducted, during which mature periphytic communities were exposed to the carotenoid-biosynthesis-inhibiting herbicide diflufenican for 12 days (up to 10 μg/L; n = 4), followed by a 9-days-lasting recovery phase in herbicide-free medium. Variables related to periphytic functioning (photosynthetic efficiency and non-photochemical quenching) and structure (pigment concentrations, biomass, and algal community structure) were quantified every third day during both experimental phases. Exposure to ≥ 0.2 μg diflufenican/L resulted in 20-25% and 25-30% lowered carotenoid and chlorophyll a concentrations, respectively, likely explained by a reduced algal biovolume as well as diflufenican's mode of toxic action and thus a shift towards a higher heterotrophy of the communities. Despite these adverse effects on the photosynthetic apparatus, the photosynthetic efficiency increased by up to ∼15% under diflufenican exposure judged on higher chlorophyll fluorescence. This may be explained by an up to ∼60% reduced non-photochemical quenching as well as binding of diflufenican to the pigment-protein membrane complex of the photosystem II, two processes causing higher chlorophyll fluorescence. Additionally, phototrophs may have actively increased energy assimilation to cope with higher energy demands under chemical stress. Although periphyton showed some recovery potential following the exposure phase, observed as increasing chlorophyll a concentrations and non-photochemical quenching, periphyton may not be able to quickly recover from stress given the persistent increase in the photosynthetic efficiency. While the processes underlying the observed effects yet remain speculative, the results suggest a shift towards a higher degree of heterotrophy in periphytic communities ultimately increasing the importance of heterotrophic ecosystem functions at impacted sites over the long term.