Macrolitter and mesolitter in the Thames Estuary: A temporal litter assessment and brand audit of submerged and riverbed debris.

Macroplastic is a growing concern for marine environments with estuaries providing a major pathway for pollution from land-based sources to the sea. In the Thames Estuary, plastic was abundant floating below the surface and on the riverbed, with an average catch per unit effort of 0.57 ± 0.42 and 2.75 ± 2.44 item per minute respectively. Whilst the abundance of litter differed between midwater and benthic zones, the types of products recovered did not. These were identified through visual examination and use of a unique citizen science engagement protocol, allowing for the item age, brand and countries of origin to be established. The majority of litter from the present study (n = 1335) was packaging (40%), some of which was over 30-years old and may have originated from landfill run off. Also abundant was sewage-related debris, the inputs of which was related to heavy or prolonged rainfall. Peaks in this material were recorded in September 2020 following the greatest volume of rain recorded in a single day and in June 2019 after the longest period of continuous rainfall. The Covid-19 pandemic did not influence the abundance or diversity of plastic recovered between December 2018 and September 2020. The durability of plastic ensures it has high potential for harm through entanglement, deoxygenation of sediment and ingestion. The retention in the environment also increases opportunities to fragment into micro- or nanoplastics and, therefore, it is important to monitor plastics at both a macro- and micro-scale.

Phase III Prospectively Randomized Trial of Perioperative 5-FU After Curative Resection for Colon Cancer: An Intergroup Trial of the ECOG-ACRIN Cancer Research Group (E1292).

BACKGROUND: Studies suggest that adjuvant chemotherapy should be initiated at the earliest possible time. The Eastern Cooperative Oncology Group (ECOG) and Intergroup evaluated the effect of perioperative fluorouracil (5-FU) on overall survival (OS) for colon cancer. PATIENTS AND METHODS: This phase III trial randomized patients to receive continuous infusional 5-FU for 7 days starting within 24 h after curative resection (arm A) or no perioperative 5-FU (arm B). Patients with Dukes' B3 and C disease received adjuvant chemotherapy per standard of care. The primary endpoint of the trial was overall survival in patients with Dukes' B3 and C disease. The secondary objective was to determine whether a week of perioperative infusion would affect survival in patients with Dukes' B2 colon cancer with no additional chemotherapy. RESULTS: From August 1993 to May 2000, 859 patients were enrolled and 855 randomized (arm A: 427; arm B: 428). The trial was terminated early due to slow accrual. The median follow-up is 15.4 years (0.03-20.3 years). Among patients with Dukes' B3 and C disease, there was no statistically significant difference in OS [median 10.3 years (95% CI 8.4, 13.2) for perioperative chemotherapy and 9.3 years (95% CI 5.7, 12.3) for no perioperative therapy, one-sided log-rank p = 0.178, HR = 0.88 (95% CI 0.66, 1.16)] or disease-free survival (DFS). For patients with Dukes' B2 disease, there was also no significant difference in OS (median 16.1 versus 12.9 years) or DFS. There was no difference between treatment arms in operative complications. One week of continuous infusion of 5-FU was tolerable; 18% of arm A patients experienced grade 3 or greater toxicity.

Safeguarding human-wildlife cooperation.

Human-wildlife cooperation occurs when humans and free-living wild animals actively coordinate their behavior to achieve a mutually beneficial outcome. These interactions provide important benefits to both the human and wildlife communities involved, have wider impacts on the local ecosystem, and represent a unique intersection of human and animal cultures. The remaining active forms are human-honeyguide and human-dolphin cooperation, but these are at risk of joining several inactive forms (including human-wolf and human-orca cooperation). Human-wildlife cooperation faces a unique set of conservation challenges, as it requires multiple components-a motivated human and wildlife partner, a suitable environment, and compatible interspecies knowledge-which face threats from ecological and cultural changes. To safeguard human-wildlife cooperation, we recommend: (i) establishing ethically sound conservation strategies together with the participating human communities; (ii) conserving opportunities for human and wildlife participation; (iii) protecting suitable environments; (iv) facilitating cultural transmission of traditional knowledge; (v) accessibly archiving Indigenous and scientific knowledge; and (vi) conducting long-term empirical studies to better understand these interactions and identify threats. Tailored safeguarding plans are therefore necessary to protect these diverse and irreplaceable interactions. Broadly, our review highlights that efforts to conserve biological and cultural diversity should carefully consider interactions between human and animal cultures. Please see AfricanHoneyguides.com/abstract-translations for Kiswahili and Portuguese translations of the abstract.

Accumulation of trace metals in freshwater macroinvertebrates across metal contamination gradients.

Historical mining activities cause widespread, long-term trace metal contamination of freshwater ecosystems. However, measuring trace metal bioavailability has proven difficult, because it depends on many factors, not least concentrations in water, sediment and habitat. Simple tools are needed to assess bioavailabilities. The use of biomonitors has been widely advocated to provide a realistic measure. To date there have been few attempts to identify ubiquitous patterns of trace metal accumulation within and between freshwater biomonitors at geographical scales relevant to trace metal contamination. Here we address this through a nationwide collection of freshwater biomonitors (species of Gammarus, Leuctra, Baetis, Rhyacophila, Hydropsyche) from 99 English and Welsh stream sites spanning a gradient of high to low trace metal loading. The study tested for inter-biomonitor variation in trace metal body burden, and for congruence amongst accumulations of trace metals within taxa and between taxa across the gradient. In general, significant differences in trace metal body burden occurred between taxa: Gammarus sp. was the most different compared with insect biomonitors. Bivariate relationships between trace metals within biomonitors reflected trace metal profiles in the environment. Strong correlations between some trace metals suggested accumulation was also influenced by physiological pathways. Bivariate relationships between insect biomonitors for body burdens of As, Cu, Mn and Pb were highly consistent. Our data show that irrespective of taxonomic or ecological differences, there is a commonality of response amongst insect taxa, indicating one or more could provide consistent measures of trace metal bioavailability.

High prevalence of plastic ingestion by Eriocheir sinensis and Carcinus maenas (Crustacea: Decapoda: Brachyura) in the Thames Estuary.

This study presents evidence for microplastic contamination in two resident species of brachyuran crab from the Thames Estuary: the native shore crab, Carcinus maenas (Linneaus, 1758) and the invasive Chinese mitten crab, Eriocheir sinensis (H. Milne Edwards, 1853). The gills, gastric mill and intestine of 94 C. maenas and 41 E. sinensis were examined. Crabs were sampled periodically (ca. every three months) between December 2018 and October 2019. A total of 874 plastics were recovered, ranging 34 µm-34 mm in length. Overall, 71.3% and 100% of C. maenas and E. sinensis, respectively, contained at least one item (fibre, film, fragment or tangle of fibres) in the gill chamber, gastric mill or gastrointestinal tract. The most common items were fibres (78.5%) but in some cases, particularly in the gastric mill, these were aggregated into tangles (7.8%). Almost all E. sinensis contained tangles of fibres (95.1%), whereas, relatively few C. maenas contained similar tangles (10.6%).

London's river of plastic: High levels of microplastics in the Thames water column.

This opportunistic study focussed on the quantification of microplastics in the River Thames water column, the catchment responsible for draining Greater London. Two sites on the tidal Thames were sampled; one upstream of the City of London at Putney, and the other downstream at Greenwich. Water column samples were collected from June through to October 2017, being taken on the ebb and flood tides, at the surface and a depth of 2 m. Microplastics (excluding microfibres) were identified to test whether the load varied between the two sites in relation to tide, depth and season. Secondary microplastics, films and fragments, contributed 93.5% of all those found at Putney and Greenwich. Site, tide, depth and month affected density, with the combined interaction of month and site found to have the greatest influence on microplastics. Fourier Transform Infrared Spectroscopy analysis showed that polyethylene and polypropylene were the most common polymers collected from the River, suggesting broken down packaging was the primary source of microplastics in these samples. Excluding microfibres, the estimate of microplastics in the water column was 24.8 per m3 at Putney and 14.2 per m3 at Greenwich. These levels are comparable to some of the highest recorded in the world.

Genomics of Population Differentiation in Humpback Dolphins, Sousa spp. in the Indo-Pacific Ocean.

Speciation is a fundamental process in evolution and crucial to the formation of biodiversity. It is a continuous and complex process, which can involve multiple interacting barriers leading to heterogeneous genomic landscapes with various peaks of divergence among populations. In this study, we used a population genomics approach to gain insights on the speciation process and to understand the population structure within the genus Sousa across its distribution in the Indo-Pacific region. We found 5 distinct clusters, corresponding to S. plumbea along the eastern African coast and the Arabian Sea, the Bangladesh population, S. chinensis off Thailand and S. sahulensis off Australian waters. We suggest that the high level of differentiation found, even across geographically close areas, is likely determined by different oceanographic features such as sea surface temperature and primary productivity.

Maculopathy in Patients with Monoclonal Gammopathy of Undetermined Significance.

PURPOSE: To describe clinical findings, laboratory values, and treatment response of patients with monoclonal gammopathy of undetermined significance (MGUS) demonstrating neurosensory macular detachment. DESIGN: Retrospective case series. PARTICIPANTS: Seven eyes of 4 patients (3 men and 1 woman; age range, 60-81 years) with neurosensory macular detachment, treatment-resistant submacular fluid, and vitelliform material. METHODS: We retrospectively reviewed the medical and ocular histories, ocular examination findings, retinal imaging, ocular disease course, and laboratory findings in 4 patients with submacular fluid associated with MGUS. MAIN OUTCOME MEASURES: Description of the macular findings and treatment courses of 4 patients diagnosed with MGUS maculopathy. RESULTS: Seven eyes of 4 patients demonstrated neurosensory macular detachment with treatment-resistant submacular fluid and vitelliform material. No eyes demonstrated signs of significant hyperviscosity retinopathy. Fluorescein angiography showed no definite leakage in any involved eye. Laboratory evaluation revealed immunoglobulin G MGUS in all 4 patients. All 4 patients were resistant to treatments aimed at resolving the subretinal fluid, including some combination of anti-vascular endothelial growth factor injections, photodynamic therapy, topical dorzolamide, oral dosing of eplerenone or acetazolamide, or some combination thereof. In 3 patients, MGUS underwent malignant transformation 24 to 144 months after diagnosis, in 1 patient to lymphoplasmacytic lymphoma and in 2 patients to multiple myeloma. The fourth patient showed no evidence of malignancy 8 years after diagnosis. CONCLUSIONS: Submacular fluid without fluorescein leakage and unresponsive to conventional treatment may suggest an underlying immunoproliferative disorder that we have termed monoclonal gammopathy of macular significance. Given the propensity for monoclonal gammopathy of macular significance to transform into malignant disease in our series, serum protein analysis should be considered in patients with neurosensory macular detachment not attributable to known causes.

Preclinical Acute Ocular Safety Study of Combined Intravitreal Carboplatin and Etoposide Phosphate for Retinoblastoma.

BACKGROUND AND OBJECTIVE: To describe the ocular toxicity of intravitreal carboplatin and etoposide phosphate (VP16P) in Dutch-Belted rabbits. MATERIALS AND METHODS: Twenty-two adult male Dutch-Belted rabbits (Cohort 1) each received a single, bilateral intravitreal injection (0.05 mL). For Cohort 1, safety was assessed via electroretinograms (ERGs) and ocular examination. Of nine total groups in Cohort 1, the first five received the following single agents: Group 1: normal saline; Group 2: VP16P 75 µg; Group 3: VP16P 100 µg; Group 4: carboplatin 4 µg; and Group 5: carboplatin 8 µg. Groups 6 through 9 received the following combination of carboplatin/ VP16P, respectively: Group 6: 8 µg/75 µg, Group 7: 8 µg/50 µg, Group 8: 4 µg/50 µg, and Group 9: 2 µg/25 µg. Cohort 2 consisted of 15 Dutch-Belted rabbits in seven groups (Groups 10 through 16), each receiving a single, bilateral intravitreal injection. For Cohort 2, safety was assessed via histopathology. RESULTS: Groups 2 through 8 demonstrated a statistically significant decrease (relative to Group 1) in at least one ERG waveform amplitude obtained 4 weeks postinjection (P < .05). Group 9 (carbo 2 µg/VP16P 25 µg) did not manifest ERG toxicity. Fundoscopic toxicity consisted of slight-to-moderate attenuation of vessels in rabbits receiving doses above carbo 4 µg/VP16P 50 µg. Histopathologic retinal toxicity (Cohort 2) was dose-dependent, ranging from full-thickness atrophy in rabbits receiving the highest dose to normal in rabbits receiving carbo 2 µg/VP16P 25 µg. CONCLUSIONS: Combined carboplatin and VP16P may be compatible for intravitreal injection therapy, and a single dose of 2 µg/25 µg appears to be safe in a rabbit model. These agents may be a safer alternative to intravitreal melphalan (Alkeran; GlaxoSmithKline, Brentford, United Kingdom) for the treatment of vitreous seeds in retinoblastoma. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:151-159.].

Caddisflies Hydropsyche spp. as biomonitors of trace metal bioavailability thresholds causing disturbance in freshwater stream benthic communities.

Demonstration of an ecotoxicological effect of raised toxic metal bioavailabilities on benthic macroinvertebrate communities in contaminated freshwater streams typically requires the labour-intensive identification and quantification of such communities before the application of multivariate statistical analysis. A simpler approach is the use of accumulated trace metal concentrations in a metal-resistant biomonitor to define thresholds that indicate the presence of raised trace metal bioavailabilities causing ecotoxicological responses in populations of more metal-sensitive members of the community. We explore further the hypothesis that concentrations of toxic metals in larvae of species of the caddisfly genus Hydropsyche can be used to predict metal-driven ecotoxicological responses in more metal-sensitive mayflies, especially ephemerellid and heptageniid mayflies, in metal-contaminated rivers. Comparative investigation of two caddisflies, Hydropsyche siltalai and Hydropsyche angustipennis, from metal-contaminated rivers in Cornwall and Upper Silesia, Poland respectively, has provided preliminary evidence that this hypothesis is applicable across caddisfly species and contaminated river systems. Use of a combined toxic unit approach, relying on independent data sets, suggested that copper and probably also arsenic are the drivers of mayfly ecotoxicity in the River Hayle and the Red River in Cornwall, while cadmium, lead and zinc are the toxic agents in the Biala Przemsza River in Poland. This approach has great potential as a simple tool to detect the more subtle effects of mixed trace metal contamination in freshwater systems. An informed choice of suitable biomonitor extends the principle to different freshwater habitats over different ranges of severity of trace metal contamination.

Re-assessment of the Conservation Status of the Indo-Pacific Humpback Dolphin (Sousa chinensis) Using the IUCN Red List Criteria.

The IUCN Red List designation of the Indo-Pacific humpback dolphin (Sousa chinensis) is re-assessed in light of its newly recognized taxonomic status (it has recently been separated into three species) and findings that humpback dolphins along the coast of Bangladesh, and possibly eastern India, are phylogenetically distinct from other members of the Sousa genus. Sousa chinensis is found in Southeast/South Asia (in both the Indian and Pacific oceans), from at least the southeastern Bay of Bengal east to central China, and then south to the Indo-Malay Archipelago. There are no global population estimates, and the sum of available abundance estimates add up to about 5700 individuals, although only a portion of the range has been covered by surveys. This species occurs in shallow (<30m deep), coastal waters of the tropics and subtropics, and feeds mainly on small fishes. It has a similar reproductive biology to other large dolphins, occurs mostly in small groups, and generally has individual movements of about 50-200km(2). Major threats throughout the range include entanglement in fishing nets (primarily gillnets) and habitat destruction/degradation, although in some more industrialized areas, vessel traffic, and environmental contamination from organochlorines are also serious issues. Conservation management is largely lacking in most parts of the species' range, although there has been significant (though still inadequate) attention in some parts of China (e.g. Hong Kong and adjacent areas, and Taiwan). Much greater efforts are needed toward conservation of Indo-Pacific humpback dolphins to stop apparent declines, and to lower the species' extinction risk. Sousa chinensis meets the IUCN Red List requirements for Vulnerable (under criteria A4cd), with fisheries bycatch and habitat loss/degradation being the main pervasive threats.

The Reliability of Estimating Ki Values for Direct, Reversible Inhibition of Cytochrome P450 Enzymes from Corresponding IC50 Values: A Retrospective Analysis of 343 Experiments.

In the present study, we conducted a retrospective analysis of 343 in vitro experiments to ascertain whether observed (experimentally determined) values of Ki for reversible cytochrome P450 (P450) inhibition could be reliably predicted by dividing the corresponding IC50 values by two, based on the relationship (for competitive inhibition) in which Ki = IC50/2 when [S] (substrate concentration) = Km (Michaelis-Menten constant). Values of Ki and IC50 were determined under the following conditions: 1) the concentration of P450 marker substrate, [S], was equal to Km (for IC50 determinations) and spanned Km (for Ki determinations); 2) the substrate incubation time was short (5 minutes) to minimize metabolism-dependent inhibition and inhibitor depletion; and 3) the concentration of human liver microsomes was low (0.1 mg/ml or less) to maximize the unbound fraction of inhibitor. Under these conditions, predicted Ki values, based on IC50/2, correlated strongly with experimentally observed Ki determinations [r = 0.940; average fold error (AFE) = 1.10]. Of the 343 predicted Ki values, 316 (92%) were within a factor of 2 of the experimentally determined Ki values, and only one value fell outside a 3-fold range. In the case of noncompetitive inhibitors, Ki values predicted from IC50/2 values were overestimated by a factor of nearly 2 (AFE = 1.85; n = 13), which is to be expected because, for noncompetitive inhibition, Ki = IC50 (not IC50/2). The results suggest that, under appropriate experimental conditions with the substrate concentration equal to Km, values of Ki for direct, reversible inhibition can be reliably estimated from values of IC50/2.

Bioaccumulation of arsenic and silver by the caddisfly larvae Hydropsyche siltalai and H. pellucidula: a biodynamic modeling approach.

Biodynamic modeling was used to investigate the uptake and bioaccumulation of arsenic and silver from water and food by two Hydropsychid caddisfly larvae: Hydropsyche siltalai and Hydropsyche pellucidula. Radiotracer techniques determined the uptake rate constants of arsenic and silver from water, and assimilation efficiencies from food, and their subsequent loss rate constants after accumulation from either route. The uptake rate constants (±SE) of As and Ag from solution were 0.021±0.005 and 0.350±0.049Lg(-1)day(-1), respectively, for H. siltalai, and 0.435±0.054 and 0.277±0.021Lg(-1)day(-1), respectively, for H. pellucidula in moderately hard synthetic water at 10°C. The assimilation efficiencies (±SE) of As and Ag from radiolabeled ingested food were 46.0±7.7% and 75.7±3.6%, respectively, for H. siltalai, and 61.0±4.2% and 52.6±8.6%, respectively, for H. pellucidula. Ag, but not As, AEs were significantly different between species. The AE of Ag differed from the AE of As in H. siltalai, but not in H. pellucidula. Mean efflux rate constants after accumulation of metals from solution or food ranged from 0.039 to 0.190day(-1). The efflux rate constants of As and Ag accumulated from solution were significantly lower than those of As and Ag assimilated from ingested food in both species. Experimentally derived ku and ke values were then used to predict As and Ag tissue concentrations in hydropsychids collected from 13 UK sites, including metal-contaminated streams in Cornwall. Arsenic and silver concentrations in environmental water and food (suspended particles) samples were measured. Biodynamic models successfully predicted accumulated As and Ag concentrations in resident H. siltalai and H. pellucidula at each site. The models also showed that more than 95% of accumulated As and almost 100% of accumulated Ag in H. siltalai and H. pellucidula are derived from ingested food rather than from water.

Bioaccumulation and oxidative stress responses measured in the estuarine ragworm (Nereis diversicolor) exposed to dissolved, nano- and bulk-sized silver.

The impact of Ag NPs on sediment-dwelling organisms has received relatively little attention, particularly in linking bioaccumulation to oxidative injury. The polychaete Nereis diversicolor was exposed to sediments spiked with dissolved Ag (added as AgNO3), Ag NPs (63 ± 27 nm) and larger bulk Ag particles (202 ± 56 µm), for up to 11 days at sublethal concentrations (nominally 2.5, 5, 10 µg Ag g(-1) sediment (dw)). There were concentration- and time-dependent differences in the accumulation of the three Ag forms, but all three forms elicited an oxidative stress response. In the cases of Ag NPs and bulk Ag particles, changes in antioxidant markers (glutathione, SOD, CAT, GPx, SeGPx, GST and GR) occurred without significant Ag accumulation. Differences in biomarker profiles between the three Ag forms suggest that the mechanism of oxidative stress caused by particulate Ag is distinct from that of dissolved Ag.

Inhibition of potential uptake pathways for silver nanoparticles in the estuarine snail Peringia ulvae.

Mechanisms involved in the uptake of Ag NPs, and NPs in general, have been long debated within nano-ecotoxicology. In vitro studies provide evidence of the different available uptake pathways, but in vivo demonstrations are lacking. In this study, pharmacological inhibitors were employed to block specific uptake pathways that have been implicated in the transport of metal NPs and aqueous metal forms; phenamil (inhibits Na(+) channel), bafilomycin A1 (H(+) proton pump), amantadine (clathrin-mediated endocytosis), nystatin (caveolae-mediated endocytosis) and phenylarsine oxide (PAO, macropinocytosis). Peringia ulvae (snails) were exposed to 150 µg Ag L(-1) added as citrate capped Ag NPs or aqueous Ag (AgNO3) in combination with inhibitor treatment (determined by preliminary studies). Reductions in accumulated tissue burdens caused by the inhibitors were compared to control exposures (i.e. no inhibition) after 6 and 24 h. No inhibitor treatment completely eliminated the uptake of Ag in either aqueous or NP form, but all inhibitor treatments, except phenamil, significantly reduced the uptake of Ag presented as Ag NPs. Clathrin- and caveolae-mediated endocytosis appear to be mechanisms exploited by Ag NPs, with the latter pathway only active at 24 h. Inhibition of the H(+) proton pump showed that a portion of Ag NP uptake is achieved as aqueous Ag and is explained by the dissolution of the particles (∼25% in 24 h). This in vivo study demonstrates that uptake of Ag from Ag NPs is achieved by multiple pathways and that these pathways are simultaneously active.

NAD+ protects against EAE by regulating CD4+ T-cell differentiation.

CD4(+) T cells are involved in the development of autoimmunity, including multiple sclerosis (MS). Here we show that nicotinamide adenine dinucleotide (NAD(+)) blocks experimental autoimmune encephalomyelitis (EAE), a mouse model of MS, by inducing immune homeostasis through CD4(+)IFNγ(+)IL-10(+) T cells and reverses disease progression by restoring tissue integrity via remyelination and neuroregeneration. We show that NAD(+) regulates CD4(+) T-cell differentiation through tryptophan hydroxylase-1 (Tph1), independently of well-established transcription factors. In the presence of NAD(+), the frequency of T-bet(-/-) CD4(+)IFNγ(+) T cells was twofold higher than wild-type CD4(+) T cells cultured in conventional T helper 1 polarizing conditions. Our findings unravel a new pathway orchestrating CD4(+) T-cell differentiation and demonstrate that NAD(+) may serve as a powerful therapeutic agent for the treatment of autoimmune and other diseases.

To see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey.

Detection of animals during visual surveys is rarely perfect or constant, and failure to account for imperfect detectability affects the accuracy of abundance estimates. Freshwater cetaceans are among the most threatened group of mammals, and visual surveys are a commonly employed method for estimating population size despite concerns over imperfect and unquantified detectability. We used a combined visual-acoustic survey to estimate detectability of Ganges River dolphins (Platanista gangetica gangetica) in four waterways of southern Bangladesh. The combined visual-acoustic survey resulted in consistently higher detectability than a single observer-team visual survey, thereby improving power to detect trends. Visual detectability was particularly low for dolphins close to meanders where these habitat features temporarily block the view of the preceding river surface. This systematic bias in detectability during visual-only surveys may lead researchers to underestimate the importance of heavily meandering river reaches. Although the benefits of acoustic surveys are increasingly recognised for marine cetaceans, they have not been widely used for monitoring abundance of freshwater cetaceans due to perceived costs and technical skill requirements. We show that acoustic surveys are in fact a relatively cost-effective approach for surveying freshwater cetaceans, once it is acknowledged that methods that do not account for imperfect detectability are of limited value for monitoring.

In vivo retention of ingested Au NPs by Daphnia magna: no evidence for trans-epithelial alimentary uptake.

In vivo studies with Daphnia magna remain inconclusive as to whether engineered nanoparticles (NPs) are internalized into tissues after ingestion. Here we used a three-pronged approach to study the in vivo retention and efflux kinetics of 20 nm citrate stabilized Au NPs ingested by this key aquatic species. Daphnids were exposed to suspended particles (600 µg L(-1)) for 5 h after which they were depurated for 24 h in clean water containing algae. Light microscopy was used to follow the passage of Au NPs through the gastrointestinal tract, Au body burdens were determined by ICP-MS (inductively coupled plasma mass spectrometry), and transmission electron microscopy (TEM) was used to examine the presence and distribution of Au NPs in tissues. Results revealed that the elimination of Au NPs was bi-phasic. The fast elimination phase lasted<1h and the rate constant at which Au (of Au NPs) was eliminated was 1.12 ± 0.34 h(-1) (±SE) which accounted for ∼75% of the ingested Au. The remaining ∼25% of the ingested Au NPs was eliminated at a 100-fold slower rate. TEM analysis revealed that Au NPs in the midgut were in close proximity to the peritrophic membrane after 1 and 24h of depuration. There were no observations of Au NP uptake at the microvilli. Thus, although Au NPs were retained in the gut lumen, there was no observable internalization into the gut epithelial cells. Similar to carbon nanotubes and CuO NPs, our findings indicate that in daphnids the in vivo retention of Au NPs does not necessarily result in their internalization.

In vitro inhibition of human liver cytochrome P450 (CYP) and UDP-glucuronosyltransferase (UGT) enzymes by rose bengal: system-dependent effects on inhibitory potential.

1. Rose bengal (4,5,6,7-tetrachloro-2',4',5',7'-tetraiodofluorescein) is being developed for the treatment of cutaneous melanoma and hepatocellular carcinoma. Interestingly, rose bengal can generate singlet oxygen species upon exposure to light. 2. We evaluated rose bengal as an in vitro inhibitor of cytochrome P450 (CYP) or UDP-glucuronosyltransferase (UGT) enzymes in both human liver microsomes (HLM) and cryopreserved human hepatocytes (CHHs) under both yellow light and dark conditions. 3. Rose bengal directly inhibited CYP3A4/5 and UGT1A6 in HLM under yellow light with inhibitor concentration that causes 50% inhibition (IC50) values of 0.072 and 0.035 µM, respectively; whereas much less inhibition was observed in the dark with the IC50 values increasing 43- and 120-fold, respectively. To determine if a more physiologically-relevant test system could be protected from such an effect, rose bengal was evaluated as an inhibitor of CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, 3A4/5 and UGT enzymes in CHH. All IC50 values were similar (64 ± 8 µM) and little to no effect of light on inhibitory potential was observed. 4. Given the IC50 values in CHH increased an order of magnitude compared to HLM and the atypical pharmacokinetics of the drug, the risk of rose bengal to cause clinically relevant drug-drug interactions is likely low, particularly when administered to cancer patients on an intermittent schedule.