Efficacy of treatments for demodex blepharitis: A systematic review and meta-analysis

Purpose We conducted a systematic review and meta-analysis to evaluate the efficacy of different treatment for Demodex blepharitis. Parameters studied were mites count, improvement of symptoms and mites’ eradication, stratified on type of treatments and mode of delivery of treatments (local or systemic). Method The PubMed, Cochrane Library, Embase, ClinicalTrials.gov, Google scholar and Science Direct databases were searched for studies reporting an efficacy of treatments for Demodex blepharitis. Results We included 19 studies (14 observational and 5 randomized clinical trials), for a total of 934 patients, 1741 eyes, and 13 different treatments. For mites count, eradication rate, and symptoms improvement, meta-analysis included fifteen, fourteen and thirteen studies, respectively. The overall effect sizes for efficiency of all treatments, globally, were 1.68 (95CI 1.25 to 2.12), 0.45 (0.26–0.64), and 0.76 (0.59–0.90), respectively. Except usual lid hygiene for mites count, Children's Hospital of Eastern Ontario ointment (CHEO) for both eradication rate and symptoms, and CHEO, 2% metronidazole ointment, and systemic metronidazole for eradication rate, all treatments were efficient. Stratified meta-analysis did not show significant differences between local and systemic treatments (1.22, 0.83 to 1.60 vs 2.24, 1.30 to 3.18 for mites count; 0.37, 0.21 to 0.54 vs 0.56, 0.06 to 0.99 for eradication rate; and 0.77, 0.58 to 0.92 vs 0.67, 0.25 to 0.98 for symptoms improvement). Conclusion We reported the efficiency of the different treatments of Demodex blepharitis. Because of less systemic side effects, local treatments seem promising molecules in the treatment of Demodex blepharitis

A cost-effective method to quantify biological surface sediment reworking

We propose a simple and inexpensive method to determine the rate and pattern of surface sediment reworking by benthic organisms. Unlike many existing methods commonly used in bioturbation studies, which usually require sediment sampling, our approach is fully non-destructive and is well suited for investigating non-cohesive fine sediments in streams and rivers. Optical tracer (e.g., luminophores or coloured sand) disappearance or appearance is assessed through time based on optical quantification of surfaces occupied by tracers. Data are used to calculate surface sediment reworking (SSR) coefficients depicting bioturbation intensities. Using this method, we evaluated reworking activity of stream organisms (three benthic invertebrates and a fish) in laboratory microcosms mimicking pool habitats or directly in the field within arenas set in depositional zones. Our method was sensitive enough to measure SSR as low as 0.2 cm2.d-1, such as triggered by intermediate density (774 m-2) of Gammarus fossarum (Amphipoda) in microcosms. In contrast, complex invertebrate community in the field and a fish (Barbatula barabatula) in laboratory microcosms were found to yield to excessively high SSR (>60 cm2.d-1). Lastly, we suggest that images acquired during experiments can be used for qualitative evaluation of species-specific effects on sediment distribution

Fine sediment reduces vertical migrations of Gammarus pulex (Crustacea: Amphipoda) in response to surface water loss

Surface and subsurface sediments in river ecosystems are recognized as refuges that may promote invertebrate survival during disturbances such as floods and streambed drying. Refuge use is spatiotemporally variable, with environmental factors including substrate composition, in particular the proportion of fine sediment (FS), affecting the ability of organisms to move through interstitial spaces. We conducted a laboratory experiment to examine the effects of FS on the movement of Gammarus pulex Linnaeus (Crustacea: Amphipoda) into subsurface sediments in response to surface water loss. We hypothesized that increasing volumes of FS would impede and ultimately prevent individuals from migrating into the sediments. To test this hypothesis, the proportion of FS (1–2 mm diameter) present within an open gravel matrix (4–16 mm diameter) was varied from 10 to 20% by volume in 2.5% increments. Under control conditions (0% FS), 93% of individuals moved into subsurface sediments as the water level was reduced. The proportion of individuals moving into the subsurface decreased to 74% at 10% FS, and at 20% FS no individuals entered the sediments, supporting our hypothesis. These results demonstrate the importance of reducing FS inputs into river ecosystems and restoring FS-clogged riverbeds, to promote refuge use during increasingly common instream disturbances

Role of the hyporheic heterotrophic biofilm on transformation and toxicity of pesticides

The role of heterotrophic biofilm of water–sediment interface in detoxification processes was tested in abiotic and biotic conditions under laboratory conditions. Three toxicants, a herbicide (Diuron), a fungicide (Dimethomorph) and an insecticide (Chlorpyrifos-ethyl) have been tested in water percolating into columns reproducing hyporheic sediment. The detoxification processes were tested by comparing the water quality after 18 days of percolation with and without heterotrophic biofilm. Tested concentrations were 30 mg.Lx1 of Diuron diluted in 0.1% dimethyl sulfoxide (DMSO), 2 mg.Lx1 of Dimethomorph and 0.1 mg.Lx1 of Chlorpyrifos-ethyl. To characterise the detoxification efficiency of the system, we performed genotoxicity bioassays in amphibian larvae and rotifers and measured the respiration and denitrification of sediments. Although the presence of biofilm increased the production of N-(3,4 dichlorophenyl)-N-(methyl)-urea, a metabolite of diuron, the toxicity did not decrease irrespective of the bioassay. In the presence of biofilm, Dimethomorph concentrations decreased compared with abiotic conditions, from 2 mg.Lx1 to 0.4 mg.Lx1 after 18 days of percolation. For both Dimethomorph and Chlorpyrifos-ethyl additions, assessment of detoxification level by the biofilm depended on the test used: detoxification effect was found with amphibian larvae bioassay and no detoxification was observed with the rotifer test. Heterotrophic biofilm exerts a major influence in the biochemical transformation of contaminants such as pesticides, suggesting that the interface between running water and sediment plays a role in self-purification of stream reaches

The role of organisms in hyporheic processes : gaps in current knowledge, needs for future research and applications

Fifty years after the hyporheic zone was first defined (Orghidan, 1959), there are still gaps in the knowledge regarding the role of biodiversity in hyporheic processes. First, some methodological questions remained unanswered regarding the interactions between biodiversity and physical processes, both for the study of habitat characteristics and interactions at different scales. Furthermore, many questions remain to be addressed to help inform our understanding of invertebrate community dynamics, especially regarding the trophic niches of organisms, the functional groups present within sediment, and their temporal changes. Understanding microbial community dynamics would require investigations about their relationship with the physical characteristics of the sediment, their diversity, their relationship with metabolic pathways, their inter- actions with invertebrates, and their response to environmental stress. Another fundamental research question is that of the importance of the hyporheic zone in the global metabolism of the river, which must be explored in relation to organic matter recycling, the effects of disturbances, and the degradation of contaminants. Finally, the application of this knowledge requires the development of methods for the estimation of hydro- logical exchanges, especially for the management of sediment clogging, the optimization of self-purification, and the integration of climate change in environmental policies. The development of descriptors of hyporheic zone health and of new metrology is also crucial to include specific targets in water policies for the long-term management of the system and a clear evaluation of restoration strategies

Direct observations of the effect of fine sediment deposition on the vertical movement of Gammarus pulex (Amphipoda: Gammaridae) during substratum drying

Benthic macroinvertebrates inhabit the streambed sediments of temporary streams during drying events. Fine sediment (< 2 mm in diameter) deposition and clogging of interstitial pathways reduces the connectivity between benthic and subsurface habitats, potentially inhibiting macroinvertebrate vertical movements. Direct observations within subsurface sediments are, however, inherently difficult. As a result, confirmation of macroinvertebrate vertical movement, and the effect of fine sediment, is limited. We used laboratory mesocosms containing transparent gravel sized particles (10–15 mm) to facilitate the direct observation and tracking of vertical movements by Gammarus pulex in response to water level reduction and sedimentation. Seven sediment treatments comprised two fine sediment fractions (small: 0.125–0.5 mm, coarse sand: 0.5–1 mm) deposited onto the surface of the substrate, and a control treatment where no fine sediment was applied. We found that G. pulex moved into the subsurface gravel sediments in response to drying, but their ability to remain submerged during water level reduction was impeded by fine sediment deposition. In particular deposition of the coarser sand fraction clogged the sediment surface, limiting vertical movements. Our results highlight the potential effect of sedimentation on G. pulex resistance to drying events in streams

A modelling approach to quantify the influence of fine sediment deposition on biogeochemical processes occurring in the hyporheic zone

Excessive sedimentation of fine particles on stream beds has been recognized as a major threat to running-water ecosystems. Deposition of fine sediments often affects hyporheic zone (HZ) functioning by (1) reducing hydrological exchanges at the water–sediment interface and by (2) increasing the organic matter (OM) content of surface sediments. These two factors usually occur concurrently to control biogeochemical processes in sediments. In the present study, experimental and modelling approaches were coupled to evaluate the contribution of these factors on the biogeochemical functioning of the HZ. We used a one-dimensional (1D) vertical model taking into account the hydrodynamic properties, the vertical distribution of the OM and the main microbial processes involved in OM processing (aerobic respiration, denitrification, nitrification and sulphate reduction). This Mobile-Immobile Model for Organic Matter (MIM-OM) model was calibrated and validated using experimental data (conservative tracer, dissolved oxygen and nitrate concentrations) obtained in filtration columns filled with a porous sedimentary matrix. Simulations showed that organic carbon content and Darcy velocity acted in concert to shape biogeochemical processes in stream sediments. The use of the MIM-OM model on data obtained in filtration columns impacted by fine sediment deposition indicated that the biodegradability of the OM (modified through the degradation parameter kPOC) also played a key role on biogeochemical processes occurring in sediments. In conclusion, the MIM-OM model appears as an efficient simulation tool to evaluate biogeochemical functioning in river sediments under different conditions (granulometry, quality of surface water and clogging)

Combining microscopy with spectroscopic and chemical methods for tracing the origin of atmospheric fallouts from mining sites

Populations living close to mining sites are often exposed to important heavy metal concentrations, especially through atmospheric fallouts. Identifying the main sources of metal-rich particles remains a challenge because of the similarity of the particle signatures from the polluted sites. This work provides an original combination of physical and chemical methods to determine the main sources of airborne particles impacting inhabited zones. Raman microspectrometry (RMS), X-ray diffraction (DRX), morphology analyses by microscopy and chemical composition were assessed. Geochemical analysis allowed the identification of target and source areas; XRD and RMS analysis identified the main mineral phases in association with their metal content and speciation. The characterization of the dominant minerals was combined with particle morphology analysis to identify fallout sources. The complete description of dust morphologies permitted the successful determination of a fingerprint of each source site. The analysis of these chemical and morphological fingerprints allowed identification of the mine area as the main contributor of metal-rich particles impacting the inhabited zone. In addition to the identification of the main sources of airborne particles, this study will also permit to better define the extent of polluted zones requiring remediation or protection from eolian erosion inducing metal-rich atmospheric fallouts

Efficacy of medical treatments for vernal keratoconjunctivitis : A systematic review and meta-analysis

Vernal keratoconjunctivitis (VKC) is a severe type of allergic conjunctivitis for which treatment strategies are still under debate. Objectives This study sought to conduct a systematic review and meta-analysis to evaluate the efficacy of medical treatments for VKC. Methods The PubMed, Cochrane Library, Embase, and ScienceDirect databases were searched to assess the efficacy of treatments for VKC. Random-effect meta-analyses on changes in clinical scores of symptoms and signs between baseline and after treatment, stratified on treatment classes, were computed. Meta-regressions were searched for potential influencing parameters. Results Included were 45 studies (27 randomized controlled trials and 18 prospective cohort studies), 1749 patients (78% were men; mean age, 11.2 years), and 12 different treatment classes. Mast cell stabilizers (MCSs; usually considered as first-line therapy), cyclosporine, and tacrolimus were the most studied drugs (in three-quarters of studies). Overall, all clinical scores improved. Total symptom and sign score decreased for MCSs (effect size, −3.19; 95% CI, –4.26 to −2.13), cyclosporine (effect size, −2.06; 95% CI, −2.72 to −1.40), and tacrolimus (effect size, −2.39; 95% CI, −3.36 to −1.43). No significant differences were shown depending on treatment classes, concentration, age, sex, baseline activity scores, and atopy. Sensitivity analyses demonstrated similar results. Conclusions This study confirms the efficacy of MCSs in the treatment of VKC. Efficacy of cyclosporine and tacrolimus did not differ, suggesting that tacrolimus is a good alternative to cyclosporine for severe cases of VKC. Further studies are needed to compare other drugs and their precise place in treatment strategy