We collected mercury observations as part of the Nitrogen, Oxidants, Mercury, and Aerosol Distributions, Sources, and Sinks (NOMADSS) aircraft campaign over the southeastern US between 1 June and ...15 July 2013. We use the GEOS-Chem chemical transport model to interpret these observations and place new constraints on bromine radical initiated mercury oxidation chemistry in the free troposphere. We find that the model reproduces the observed mean concentration of total atmospheric mercury (THg) (observations: 1.49 ± 0.16 ng m−3, model: 1.51 ± 0.08 ng m−3), as well as the vertical profile of THg. The majority (65 %) of observations of oxidized mercury (Hg(II)) were below the instrument's detection limit (detection limit per flight: 58–228 pg m−3), consistent with model-calculated Hg(II) concentrations of 0–196 pg m−3. However, for observations above the detection limit we find that modeled Hg(II) concentrations are a factor of 3 too low (observations: 212 ± 112 pg m−3, model: 67 ± 44 pg m−3). The highest Hg(II) concentrations, 300–680 pg m−3, were observed in dry (RH < 35 %) and clean air masses during two flights over Texas at 5–7 km altitude and off the North Carolina coast at 1–3 km. The GEOS-Chem model, back trajectories and observed chemical tracers for these air masses indicate subsidence and transport from the upper and middle troposphere of the subtropical anticyclones, where fast oxidation of elemental mercury (Hg(0)) to Hg(II) and lack of Hg(II) removal lead to efficient accumulation of Hg(II). We hypothesize that the most likely explanation for the model bias is a systematic underestimate of the Hg(0) + Br reaction rate. We find that sensitivity simulations with tripled bromine radical concentrations or a faster oxidation rate constant for Hg(0) + Br, result in 1.5–2 times higher modeled Hg(II) concentrations and improved agreement with the observations. The modeled tropospheric lifetime of Hg(0) against oxidation to Hg(II) decreases from 5 months in the base simulation to 2.8–1.2 months in our sensitivity simulations. In order to maintain the modeled global burden of THg, we need to increase the in-cloud reduction of Hg(II), thus leading to faster chemical cycling between Hg(0) and Hg(II). Observations and model results for the NOMADSS campaign suggest that the subtropical anticyclones are significant global sources of Hg(II).
The liver is the predominant site of metastases among patients with advanced neuroendocrine tumors (NETs). Prior retrospective studies have reported high response rates in patients treated with ...transarterial embolization (TAE). NETs are highly vascular and are known to express vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor (VEGFR). We hypothesized that administration of sunitinib, a VEGFR inhibitor, following TAE would extend progression-free survival (PFS).
Patients with metastatic NETs to the liver underwent a series of selective TAEs followed by sunitinib (until disease progression or maximum of 12 months). Radiographic response (by RECIST), survival, and safety parameters were monitored.
Thirty-nine patients were enrolled. The overall response rate was 72% 95% confidence interval (CI), 0.58–0.86. Median PFS was 15.2 months. Rates of overall survival (OS) at 1 and 4 years were 95% (95% CI, 0.88–1.00) and 59% (95% CI, 0.38–0.80), respectively. A significant 34% rise in serum VEGF was observed following the initial TAE (P=0.03).
Hepatic TAE is a highly active treatment option for patients with metastatic NETs to the liver. Embolization stimulates release of VEGF into the circulation. Sunitinib, an oral VEGFR inhibitor, can be safely administered following embolization. The high rates of PFS and OS associated with this sequence of therapies are encouraging.
Freshwater sediments are a repository of microplastics (MPs) resulting from inland anthropogenic activities. Benthic invertebrates, particularly endobenthic sediment–ingesting species such as the ...annelid Lumbriculus variegatus (blackworm), are commonly found in contaminated sediments where they likely find and ingest MPs. In the present study, L. variegatus was exposed to concentrations between 0.51 and 20 g kg−1 dry sediment of four size-classes of irregularly-shaped polyethylene MPs (PE-MPs; size-class A: 32–63, B: 63–125, C: 125–250 and D: 250–500 μm) for 48 h to assess their sub-cellular responses to particles ingested, and for 28 days to determine chronic effects on worm's reproduction and biomass.
After the short-term exposure (48 h), number of PE-MPs in blackworms' gut were related to MPs concentration in the sediment. In general, PE-MPs ingestion by blackworms induced depletion of their energy reserves (e.g., sugars in all size classes and lipids in the size-classes of PE-MPs > 125 μm), concomitant with the activation of antioxidant and detoxification mechanisms (increased level of total glutathione in all size-classes, and increased glutathione-S-transferase activity in PE-MPs > 250 μm), preventing lipid peroxidation. In addition, it was observed a reduction of aerobic energy production (decreased activity of the electron transport system) and a slight increase in neurotransmission (cholinesterase activity). After a long-term exposure (28 d), the presence and ingestion of PE-MPs did not affect reproduction and biomass of L. variegatus.
The activation and efficiency of the antioxidant and detoxification mechanisms allied with the anatomy and physiology of L. variegatus, its feeding strategy and potentially dynamic ingestion/egestion capacity seem to be key features preventing MP deleterious effects under short- and chronic-exposures. Considering the MPs levels reported for freshwater sediments, and despite evidence of MPs ingestion and some sub-organismal effects, our results suggest no adverse impacts of PE-MPs contamination on L. variegatus populations fitness.
This study applies an integrative approach in which data concerning the ingestion of different sized MPs and subsequent sub-cellular and apical responses are delivered, raising knowledge on endobenthic invertebrates’ strategies to potentially overcome MP toxicity in field contaminated sites.
Display omitted
•Lumbriculus variegatus ingested low numbers of polyethylene microplastics (PE-MPs).•L. variegatus exposed to PE-MPs showed reduced energy reserves and aerobic energy production.•PE-MPs ingestion also triggered antioxidant and detoxification processes.•Long-term exposure to PE-MPs caused no effects on L. variegatus reproduction and biomass.
This study aimed at characterizing a biosurfactant from
Candida utilis
, and use it in the preparation of salad dressings. The biosurfactant was produced in mineral medium supplemented with 6% ...glucose and 6% waste frying canola oil. The crude biosurfactant was then tested for stability in different conditions of pH, salt concentration, heating time and temperature. The critical micelle dilution, chemical composition, and structural analysis were determined. The compound was resistant to extreme conditions and presented stable surface tension and emulsification activity in alkaline pH and was characterized as a carbohydrate-lipid-protein complex showing the best formulation and consistency at 0.7% (w/v) with guar gum indicating potential applicability in food emulsions.
BACKGROUND
The objective of this study was to examine the relation between dietary fats and semen quality parameters.
METHODS
Data from 99 men with complete dietary and semen quality data were ...analyzed. Fatty acid levels in sperm and seminal plasma were measured using gas chromatography in a subgroup of men (n = 23). Linear regression was used to determine associations while adjusting for potential confounders.
RESULTS
Men were primarily Caucasian (89%) with a mean (SD) age of 36.4 (5.3) years; 71% were overweight or obese; and 67% were never smokers. Higher total fat intake was negatively related to total sperm count and concentration. Men in the highest third of total fat intake had 43% (95% confidence interval (CI): 62–14%) lower total sperm count and 38% (95% CI: 58–10%) lower sperm concentration than men in the lowest third (Ptrend = 0.01). This association was driven by intake of saturated fats. Levels of saturated fatty acids in sperm were also negatively related to sperm concentration (r= −0.53), but saturated fat intake was unrelated to sperm levels (r = 0.09). Higher intake of omega-3 polyunsaturated fats was related to a more favorable sperm morphology. Men in the highest third of omega-3 fatty acids had 1.9% (0.4–3.5%) higher normal morphology than men in the lowest third (Ptrend = 0.02).
CONCLUSIONS
In this preliminary cross-sectional study, high intake of saturated fats was negatively related to sperm concentration whereas higher intake of omega-3 fats was positively related to sperm morphology. Further, studies with larger samples are now required to confirm these findings.
Neuropathic orofacial pain conditions represent a challenge to diagnose and treat. Natural substances are promising therapeutic options for the control of pain.
This study aimed to examine whether ...(−)-α-bisabolol (BISA), a natural terpene, can attenuate nociceptive behaviour and central sensitisation in a rodent model of trigeminal neuropathic pain.
Infraorbital nerve transection (IONX) or sham operation was performed in adult male rats. Head withdrawal thresholds as a measure of facial mechanical sensitivity were tested with von Frey monofilaments applied bilaterally to the facial vibrissal pad pre-operatively (baseline) and then post-operatively before and at 60, 120, 240 and 360 min after administration of vehicle control per oris (p.o.) or BISA (200 mg/kg p.o.) (n = 8/group). Effects of BISA or vehicle on the activity of nociceptive neurons recorded in the medullary dorsal horn (MDH) were tested on post - operative day 8–10. ANOVA followed by post-hoc Bonferroni tested for statistically significant differences (p < 0.05) across study groups and time points.
IONX animals (but not sham or naïve animals) showed post-operative facial mechanical hypersensitivity that was unaffected by vehicle. However, administration of BISA at post-operative day 7 significantly reversed the mechanical hypersensitivity in IONX rats; this effect lasted for at least 6 h. BISA also attenuated IONX-induced central sensitisation of MDH nociceptive neurons, as reflected in reversal of their reduced activation thresholds, increased responses to graded mechanical stimuli and enhanced spontaneous activity.
BISA may attenuate nociceptive behaviour and central sensitisation in a rat model of acute trigeminal neuropathic pain.
Display omitted
•Chironomus riparius larvae ingested PE-MPs from contaminated sediment.•Highest accumulation of PE-MPs in larvae guts was within the size range of 32-63 μm.•Depletion of lipid content ...was observed in larvae exposed to PE-MPs.•Ingested PE-MPs induced oxidative damage and reduced the aerobic energy production.
Riverine sediments are major sinks of microplastics from inland anthropogenic activities, imposing a threat to freshwater benthic invertebrates. This study investigated the ingestion of three size-classes (SC) of irregularly shaped polyethylene microplastics (PE-MPs; SC I: 32−63 μm; II: 63−250 μm; III: 125−500 μm) after 48 h by dipteran larvae (detritivore/collector) Chironomus riparius, and the consequent effects on neurotransmission, energy allocation and oxidative stress. The tested PE-MPs concentrations (1.25; 5; 20 g kg−1) were within the range of concentrations reported in riverbanks from highly urbanised areas (1 - 9 g kg−1), except for 20 g kg−1 representing the worst-case scenario. After exposure to SC I, larvae presented high amounts (up to ∼2400 particles/organism) of PE-MPs in their guts, with an average size-range of 30−60 μm. In the SC II and III, larvae presented PE-MPs of higher diameter (up to 125 μm) and a visible gut obstruction. The high number of particles in the larval gut (SC I) and/or difficulties for their egestion (SC I, II and III) induced oxidative damage and reduced aerobic energy production. In addition, larvae exposed to SC II and III revealed depletion in their total lipid reserves as a consequence of lacking nutrients, and the ones exposed to SC III presented a decrease in their detoxification capacity.
These results highlight that freshwater detritivores with low selective feeding behaviour (e.g., chironomids) are more prone to ingest microplastics, with potentially adverse effects on cellular metabolism, redox status and antioxidant-detoxification defences. These harmful effects at lower levels of the biological organisation may ultimately affect organisms’ physiology and fitness.
In the tropical Atlantic Ocean, the Intertropical Convergence Zone (ITCZ) is an important climate feature controlled by the interhemispheric sea surface temperature (SST) gradient, and greatly ...influences rainfall patterns over the adjacent continents. To better understand ITCZ dynamics in the context of past and future climate change, long-term oceanic records are needed, but observational data are limited in temporal extent. Shallow-water corals provide seasonally-resolved archives of climate variability over the tropical ocean. Here we present seasonally-resolved records of stable oxygen (δ18O) and carbon (δ13C) isotope values of a Siderastrea stellata coral from northeastern Brazil (Maracajaú, ~5°S). We show that the long-term trends in the record of coral δ18O values are not primarily driven by SST but by hydrological changes at the sea surface. Combining the record of coral δ18O values with instrumental SST, we present the first reconstruction of seawater δ18O changes (δ18Oseawater) in the western tropical South Atlantic back to the early 20th century, a parameter that is related to changes in sea surface salinity. The reconstructed δ18Oseawater changes indicate a prominent freshening between the mid-1940's and mid-1970's, which coincides with a weakening of the Atlantic interhemispheric SST gradient during this time interval. Our results suggest that the weakened Atlantic SST gradient resulted in a southward shift of the thermal equator that was accompanied by a southward migration of the ITCZ, resulting in freshening of the western tropical South Atlantic during the mid to late 20th century.
•First century-long coral isotopic record from the western tropical South Atlantic.•Major sea-surface freshening during the mid-20th century.•ITCZ southward migration due to changes in Atlantic sea-surface temperatures.
The high levels of microplastics (MPs) found in freshwaters, particularly in riverine sediments, may impose a threat to the macroinvertebrate communities with possible consequences at ...ecosystem-level. The present study aimed to assess the effects of a mixture of different sizes of polyethylene microplastics (PE-MPs) on the composition and structure of macroinvertebrate communities and key-functions, such as primary production and leaf litter decomposition. MPs were mixed in the sediment at three different concentrations (0.1, 1, and 10 g kg-1) already found in freshwater sediments to enhance the relevance of the work. After eight days of exposure to PE-MPs, the observed changes in macroinvertebrate community structure were mostly due to the reduction in the abundance of deposit-feeders and grazers that were reduced by ca 31-50% and 34-39%, in the two highest MPs concentrations respectively, in comparison with the control treatment after 8 days of exposure. MPs internal concentrations were detected only in organisms exposed to plastic particles within artificial streams with chironomids and mayflies presenting higher MPs internal levels (average of 115 particles/individual found in chironomids, 166/individual for Baetis sp. and 415 particles/individual for Ephemerella sp.) suggesting higher ingestion of plastic microparticles. Nevertheless, the alterations in the community structure did not translate into impairments in the functional endpoints analysed, leaf litter decomposition and primary production, that were expected due to possible sub-lethal effects (e.g., feeding inhibition) on detritivores and grazers.
This study represents one of the few assessments of MPs effects on freshwater benthic macroinvertebrate community structure and the first that simultaneously considered ecosystem-level functional endpoints. Further research combining different microplastics and longer exposure periods are needed to raise knowledge on potential ecological consequences of MPs to freshwaters.
Display omitted
•Ecological effects of polyethylene microplastics (PE-MPs) were examined in indoor mesocosms.•PE-MPs exposure induced alterations in benthic macroinvertebrate community structure.•Higher Internal concentrations of PE-MPs detected for deposit-feeders and grazers.•Leaf litter decomposition and primary production were not significantly altered by PE-MPs in sediments.
Despite being considered environmentally safe, a deeper environmental risk assessment is needed for microbial insecticides; special attention should be devoted to their sublethal toxicity to ...non-target species.
This study evaluated effects of VectoBac® 12AS - VB (based on the bacterium Bacillus thurigiensis var. israelensis) and Naturalis®-L - NL (based on the fungus Beauveria bassiana) on the aquatic insect Chironomus riparius life-history and biochemical responses.
Acute tests estimated a 48 h-LC50 (median lethal concentration) of 1.85 μg/L (VB) and 34.7 mg/L (NL). Under sublethal exposure, VB decreased adults' emergence (LOEC – lowest observed effect concentration of 80 ng/L) while NL impaired larval growth (LOEC of 0.32 mg/L) and delayed emergence (LOEC of 2 mg/L for males and 0.8 mg/L for females). Despite not being monotonic, phenoloxidase activity increased (LOEC of 20 ng/L (VB) and 2 mg/L (NL)), suggesting activation of the immune system. There were no indications of oxidative damage nor neurotoxicity. Catalase activity was stimulated with all VB treatments, possibly associated with detoxification of immune response products. Under NL exposure, glutathione-S-transferase activity increased but did not show a dose-dependent response and, total glutathione decreased in the highest concentration. Exposure to both formulations caused the increase in protein content, while carbohydrate and lipids were not altered.
This study revealed the susceptibility of C. riparius to VB and NL at concentrations below the ones recommended for field application, with potential population-level effects. These results add important information for the risk assessment of these microbial insecticides in aquatic ecosystems, considering relevant sublethal endpoints and raising concern about the adverse effects on non-target aquatic organisms.
Display omitted
•Data on sublethal effects of bioinsecticides in aquatic invertebrates is limited.•VB and NL induced distinct effects in life-history and biochemical responses.•VB affected the number of emerged imagoes and NL decreased development time.•Non-monotic PO activity activation as a defense mechanism to VB and NL•VB and NL induced CAT activity and tGSH consumption respectively
PDF
