Oncogenic p53 triggers amyloid aggregation of p63 and p73 liquid droplets.

P53 Phase separation is crucial towards amyloid aggregation and p63 and p73 have enhanced expression in tumors. This study examines the phase behaviors of p53, p63, and p73. Here we show that unlike the DNA-binding domain of p53 (p53C), the p63C and p73C undergo phase separation, but do not form amyloids under physiological temperatures. Wild-type and mutant p53C form droplets at 4°C and aggregates at 37 °C with amyloid properties. Mutant p53C promotes amyloid-like states in p63C and p73C, recruiting them into membraneless organelles. Amyloid conversion is supported by thioflavin T and Congo red binding, increased light scattering, and circular dichroism. Full-length mutant p53 and p63C (or p73C) co-transfection shows reduced fluorescence recovery after photobleaching. Heparin inhibits the prion-like aggregation of p63C and p73C induced by p53C. These findings highlight the role of p53 in initiating amyloid aggregation in p63 and p73, opening avenues for targeting prion-like conversion in cancer therapy.

Photoluminescence and magnetic properties of isostructural europium(III), gadolinium(III) and terbium(III) oxamate-based coordination polymers.

Developing and investigating advanced multifunctional materials with magnetic properties as candidates for assembling spin qubits for quantum computing is imperative. A new polytopic ligand based on oxamate and aniline was used to promote the synthesis of three neutral homometallic lanthanide-coordinated polymers. New complexes with the formula {Ln(phox)3(DMSO)2(H2O)}n, where Ln = Eu3+ (1), Gd3+ (2), and Tb3+ (3) [phox = N-(phenyl)oxamate and DMSO = dimethylsulfoxide], were synthesized and well characterized by spectroscopic methods as well as X-ray crystallographic analysis. All crystalline structures comprise neutral zigzag chains. The lanthanide ions are linked by three phox ligands, in which two oxygen atoms from two different ligands are responsible for connecting the trivalent lanthanide ions, and one phox ligand completes the coordination sphere in a bis-bidentate mode, together with two DMSO molecules and one water coordination molecule. The coordination sphere of lanthanide ions consisted of spherical capped square antiprism (CSAPR-9) symmetry. The magnetic properties of 1-3 were investigated in the 2-300 K temperature range. The dynamic (ac) magnetic properties of 2 reveal a frequency dependence involving the phonon bottleneck mechanism below 33 K under nonzero applied dc magnetic fields, resulting in an example of a field-induced single-molecule magnet. Solid-state photophysical measurements for Eu3+ (1) and Tb3+ (3) complexes indicate that the N-(phenyl)oxamate ligands are very efficient in sensitizing the lanthanide(III) ions in the visible region of the electromagnetic spectrum. Compounds 1 and 3 exhibited an emission in the red and green regions, respectively. Experimental results and theoretical calculations using the Sparkle/RM1 method support a quantum efficiency of ∼72% for 1, suggesting its potential as a candidate for light conversion molecular devices (LCMDs).

Crystal structure and cryomagnetic study of a mononuclear erbium(III) oxamate inclusion complex.

The synthesis, crystal structure and magnetic properties of an oxamate-containing erbium(III) complex, namely, tetrabutylammonium aqua[N-(2,4,6-trimethylphenyl)oxamato]erbium(III)-dimethyl sulfoxide-water (1/3/1.5), (C16H36N)[Er(C11H12NO3)4(H2O)]·3C2H6OS·1.5H2O or n-Bu4N[Er(Htmpa)4(H2O)]·3DMSO·1.5H2O (1), are reported. The crystal structure of 1 reveals the occurrence of an erbium(III) ion, which is surrounded by four N-phenyl-substituted oxamate ligands and one water molecule in a nine-coordinated environment, together with one tetrabutylammonium cation acting as a counter-ion, and one water and three dimethyl sulfoxide (DMSO) molecules of crystallization. Variable-temperature static (dc) and dynamic (ac) magnetic measurements were carried out for this mononuclear complex, revealing that it behaves as a field-induced single-ion magnet (SIM) below 5.0 K.

Oxidative responses in small juveniles of Colossoma macropomum anesthetized and sedated with Ocimum gratissimum L. essential oil.

This study evaluated the use of essential oil of Ocimum gratissimum (EOOG) for anesthesia and in transport of Colossoma macropomum. Experiment 1, Test 1, anesthesia induction and recovery times were determined using different EOOG concentrations (0, 20, 50, 100, 200, 300 mg L-1), with two size classes: Juveniles I (0.86 g) and Juveniles II (11.46 g) (independent tests in a completely randomized design). Based on the results of Test 1, in Test 2 Juveniles II were exposed to EOOG concentrations: 0, 20, 100 mg L-1. Tissue samples were collected immediately after induction and 1 h post-recovery, to assess oxidative status variables. Experiment 2, Juveniles I (0.91 g) and Juveniles II (14.76 g) were submitted to transport in water with different concentrations of EOOG (0, 5, 10 mg L-1) (independent tests in a completely randomized design). The effects on oxidative status variables were evaluated. Concentrations between 50 and 200 mg L-1 EOOG can be indicated for Juveniles I, while concentrations between 50 and 100 mg L-1 EOOG for Juveniles II. The concentration of 100 mg L-1 EOOG was able to prevent oxidative damage in the liver. In Experiment 2, the concentrations of 5 and 10 mg L-1 EOOG added to the transport water caused sedation for both studied size classes of juveniles and did not cause oscillations in water quality variables nor any mortality. The concentration of 10 mg L-1 EOOG improved the oxidative status. It can be concluded that EOOG can be used for anesthesia and transport of C. macropomum.

Morphological and Structural Characterization of (Pt, Au, and Ag) Nanoparticle/Zn-MOF-74 Composites.

Metallic nanoparticles (NPs) were decorated onto Zn-MOF-74 crystals by photoreducing different metal precursors (Pt, Au, and Ag) using ultraviolet (UV) light in an aqueous solution with different metal concentrations without using additional stabilizers. X-ray diffraction revealed the three-dimensional structural integrity and crystallinity conservation of Zn-MOF-74 crystals during the UV decoration process. Raman spectroscopy showed a minor rearrangement in the structure of the Zn-MOF-74 crystal surface after NP decoration. X-ray photoelectron spectroscopy confirmed the metal oxidation states of Zn and NPs. High-resolution transmission electron microscopy images proved the surface decoration of Zn-MOF-74 crystals with spherical metallic NPs with diameters between 2.4 and 9.8 nm.

Nasal septum-derived chondroprogenitor cells control mandibular condylar resorption consequent to orthognathic surgery: a clinical trial.

Condylar resorption is an aggressive and disability form of temporomandibular joint (TMJ) degenerative disease, usually non-respondent to conservative or minimally invasive therapies and often leading to surgical intervention and prostheses implantation. This condition is also one of the most dreaded postoperative complications of orthognathic surgery, with severe cartilage erosion and loss of subchondral bone volume and mineral density, associated with a painful or not inflammatory processes. Because regenerative medicine has emerged as an alternative for orthopedic cases with advanced degenerative joint disease, we conducted a phase I/IIa clinical trial (U1111-1194-6997) to evaluate the safety and efficacy of autologous nasal septal chondroprogenitor cells. Ten participants underwent biopsy of the nasal septum cartilage during their orthognathic surgery. The harvested cells were cultured in vitro and analyzed for viability, presence of phenotype markers for mesenchymal stem and/or chondroprogenitor cells, and the potential to differentiate into chondrocytes, adipocytes, and osteoblasts. After the intra-articular injection of the cell therapy, clinical follow-up was performed using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) and computed tomography (CT) images. No serious adverse events related to the cell therapy injection were observed during the 12-month follow-up period. It was found that autologous chondroprogenitors reduced arthralgia, promoted stabilization of mandibular function and condylar volume, and regeneration of condylar tissues. This study demonstrates that chondroprogenitor cells from the nasal septum may be a promise strategy for the treatment of temporomandibular degenerative joint disease that do not respond to other conservative therapies.

Redox profile of silver catfish challenged with Aeromonas hydrophila and treated with hexane extract of Hesperozygis ringens (Benth.) Epling through immersion bath.

The growing increase in the fish farming sector has favored the establishment of bacterial outbreaks caused by Aeromonas hydrophila in several species. The hexane extract of Hesperozygis ringens (HEHR) (Lamiaceae) leaves increased the survival rate of silver catfish (Rhamdia quelen) experimentally infected by A. hydrophila. However, it is noteworthy that no reports have been found on the possible mechanisms of action of this extract in infected fish. This study aimed to evaluate the effect of the HEHR, administered through single immersion bath, on lipid peroxidation and antioxidant defenses in muscle and liver tissue of silver catfish challenged with A. hydrophila. The results showed that the oxidative status of silver catfish was altered, although oxidative stress was not triggered during the experiment. HEHR at 30 mg/L (HEHR30) was not characterized as a pro-oxidant agent in the presence of infection, unlike florfenicol and HEHR at 15 mg/L treatments in some cases. In short, HEHR30 provided an important increase in hepatic catalase activity, characterizing one of the possible mechanisms involved in the greater survival of fish experimentally infected by A. hydrophila. Additionally, HEHR30 did not induce lipid peroxidation, nor reduced antioxidant defenses of silver catfish infected or not by A. hydrophila.

Soft-tissue, non-osteogenic distraction of the mandible and lower face in bilateral hemifacial microsomia-technical report.

The aim of this study is to present a sequential strategy of soft-tissue, non-osteogenic distraction with a novel device, followed by microvascular bony reconstruction for severe cases of mandibular hypoplasia. The case of a 21-year-old woman with Goldenhar syndrome is presented, whose mandible remained severely hypoplastic despite previous attempts at distraction and was not suitable for further osteogenic distraction. Soft tissue deficiency and pin track scarring prevented free fibular transfers. A personalized distractor, anchored to the cranium and the mandibular symphysis, was designed to expand the soft tissues while allowing for physiological temporomandibular joint (TMJ) movement without compression forces. Internal distractors were placed along the osteotomies to prevent condylar luxation. After completion of the soft tissue distraction, the native mandible was resected except for the condyles and reconstructed with two free fibula flaps. This report represents the proof of concept of a sequential approach to severe lower face soft-tissue and bone deficiency, which preserves TMJ function and avoids the transfer of poorly matched skin to the face.

Bitter ginger (Zingiber zerumbet) for patients with solid tumors with no treatment options: A pilot clinical study.

INTRODUCTION: Zerumbone is a natural compound found in bitter ginger plants (Zingiber zerumbet) that shows antiproliferative, antioxidant, anti-inflammatory, and analgesic properties. We aimed to investigate the role of zerumbone in improving the quality of life and symptom control in cancer patients with no treatment options. METHODS: We conducted a pilot, non-randomized, single-center, open prospective, and systematic study on the use of 400 mg of zerumbone twice a day. RESULTS: The study included 35 patients (mean age, 68 years; 64% men), of which 16 completed the eight-week study. The intention-to-treat population showed no significant changes in weight or sleep quality over the eight-week study. Assessments performed using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) showed significant improvements in the quality of life in the global (p = 0.072), activity (p = 0.0393), social (p = 0.0001), and emotional (p = 0.0023) dimensions. The Hospital Anxiety and Depression Scale (HADS) questionnaire scores showed significant improvement in anxiety (p = 0.032) and depression (p = 0.021), while the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) questionnaire scores also indicated a significant improvement (p = 0.001). Bitter ginger showed low toxicity. CONCLUSIONS: Bitter ginger showed promising results in improving the quality of life and reducing symptoms of anxiety and depression in the study population. A randomized placebo-controlled study is necessary to confirm these results. This trial was registered under the number FMABC: CAAE - 93459418.00000082, at ISRCTN (BIOMED CENTRAL) NUMBER 4388 (03/07/23) and at Plataforma Brasil (https://plataformabrasil.saude.gov.br/login.jsf).

Efficacy and safety of bexagliflozin in patients with type 2 diabetes mellitus: A systematic review and meta-analysis.

AIM: To assess the efficacy of bexagliflozin in reducing glycated haemoglobin (HbA1c) and the occurrence of side effects in patients with type 2 diabetes (T2DM). METHODS: We searched the PubMed, Embase, Cochrane and ClinicalTrials.gov databases for placebo-controlled, randomized clinical trials published up until 15 February 2023. The primary outcome was change in HbA1c. We computed weighted mean differences (WMDs) for continuous outcomes and odds ratios (ORs) for binary endpoints, with 95% confidence intervals (CIs). RESULTS: A total of six studies and 3111 patients were included, of whom 1951 were prescribed bexagliflozin. Compared with placebo, bexagliflozin significantly reduced HbA1c levels (WMD -0.53%; 95% CI -0.75, -0.31), fasting plasma glucose levels (WMD -1.45 mmol/L; 95% CI -2.32, -0.57), systolic blood pressure (WMD -4.66 mmHg; 95% CI -6.41, -2.92), diastolic blood pressure (WMD -2.12 mmHg; 95% CI -3.94, -0.30), body weight overall (WMD -1.61 kg; 95% CI -2.14, -1.07), and body weight in patients with a body mass index >25 kg/m2 (WMD -2.05 kg; 95% CI -2.78, -1.31). The proportion of patients who achieved HbA1c < 7% was higher in patients who received bexagliflozin as compared with placebo (OR 1.94; 95% CI 1.36-2.78). There were no significant differences between groups regarding side effects such as hypoglycaemia, genital mycotic infection, urinary tract infection, diarrhoea, headache, nausea, polyuria, diabetic ketoacidosis, or all-cause mortality. CONCLUSIONS: In this meta-analysis, the use of bexagliflozin was associated with improved clinical and laboratory measures in patients with T2DM compared with placebo, with a similar profile of side effects. These findings support the efficacy of bexagliflozin in the treatment of T2DM.

Causal validation of the risk for corneal injury in critically ill adults.

BACKGROUND: The validity of a nursing diagnosis depends on a continuous investigation process in different populations to provide clinical evidence. The risk for corneal injury nursing diagnosis was approved in 2013 and only reviewed in 2017, demonstrating the need to perform a clinical validation to improve it. AIM: To perform a causal validation of the risk for corneal injury nursing diagnosis in critically ill adults. STUDY DESIGN: A prospective cohort study was performed in two intensive critical care units in Northern Brazil with adults aged over 18 years without corneal injury at admission. The patients were evaluated for 10 days, using a data collection tool composed of risk factors for the risk for corneal injury nursing diagnosis. The independent variables were described through absolute and relative frequency. The accuracy measures and risk factors were identified through Cox regression, considering a 95% confidence interval. RESULTS: The nurses assessed 209 critically ill adults and identified that 76.0% of them presented the risk for corneal injury nursing diagnosis, with 16.3% developing a corneal injury, all having previously presented the risk for corneal injury nursing diagnosis. The risk factors identified were eyeball exposure (hazard ratio: 1.78; 95% CI: 1.27-2.51), Glasgow score < 6 (hazard ratio: 1.73; 95% CI: 1.15-2.60) and periorbital oedema (hazard ratio: 1.43; 95% CI: 1.03-1.99), with these factors showing high specificity, and the mechanical ventilation variable, showing high sensitivity, with ROC curve of .86. CONCLUSION: Eyeball exposure, Glasgow score < 6 and periorbital oedema are the risk factors of the risk for corneal injury nursing diagnosis, in critically ill adults. These risk factors guide nursing interventions. This causal validation can improve the risk for corneal injury nursing diagnosis levels of evidence in the NANDA International Taxonomy. RELEVANCE TO CLINICAL PRACTICE: It is necessary to guide nursing interventions for critically ill adults with lowered level of consciousness and corneal exposure for the prevention of corneal injury.

BRAZILIAN CONSENSUS STATEMENT ON VISCOSUPPLEMENTATION OF THE HIP (COBRAVI-Q).

Objective: The Brazilian Consensus on Hip Viscosupplementation aims to generate a referential and consensual source from the theoretical knowledge and clinical experience of specialists in the field. Methods: A multidisciplinary panel was formed with 15 specialists (sports medicine, orthopedists, physiatrists and rheumatologists), based on clinical and academic experience in the use of viscosupplementation of the hip. 12 statements were prepared, discussed and voted. Each panelist gave a value between 0 and 10 on a Likert scale, specifying their level of agreement with the statement. Results: The panel reached a consensus on several aspects of viscosupplementation of the hip, with emphasis on the following statements: best indication is for mild to moderate hip arthrosis; it may be indicated in severe osteoarthritis; results may vary according to the characteristics of the viscosupplement used; Viscosupplementation should not be performed as an isolated procedure, but in conjunction with other rehabilitation and pharmacological measures; best injection technique should be based on anatomical references coupled with imaging guidance; it is a cost-effective procedure. Conclusion: Viscosupplementation is a safe and effective therapy for hip osteoarthritis, even in severe cases. Guided injection is recommended. Level of Evidence V, Expert Opinion.

Objetivo: O Consenso Brasileiro de Viscossuplementação do Quadril visa gerar uma fonte referencial a partir do conhecimento teórico e da experiência clínica de especialistas da área. Métodos: Um painel multidisciplinar foi formado com quinze especialistas (médicos do esporte, ortopedistas, fisiatras e reumatologistas), com base na experiência clínica e acadêmica no uso da viscossuplementação do quadril. Foram elaboradas, discutidas e votadas doze afirmativas. Cada membro do painel deu um valor entre 0 e 10 numa escala tipo Likert, especificando seu nível de concordância com a afirmação. Resultados: O painel chegou a um consenso sobre diversos aspectos da viscossuplementação do quadril, destacando-se: a melhor indicação é para tratar artrose de quadril leve a moderada; pode ser indicada para casos graves; os resultados podem variar de acordo com o viscossuplemento utilizado; não deve ser realizada como procedimento isolado, mas em conjunto com outras medidas reabilitadoras e farmacológicas; a melhor técnica para infiltração no quadril deve se basear nas referências anatômicas combinadas com guiagem por imagem; a viscossuplementação do quadril é um procedimento custo-efetivo. Conclusão: A viscossuplementação é uma alternativa terapêutica segura e eficaz na osteoartrite do quadril, mesmo em casos graves. Recomenda-se o uso de métodos guiados. Nível de Evidência V, Opinião do Especialista.

Maternal low-protein diet reduces skeletal muscle protein synthesis and mass via Akt-mTOR pathway in adult rats.

Several studies have demonstrated that a maternal low-protein diet induces long-term metabolic disorders, but the involved mechanisms are unclear. This study investigated the molecular effects of a low-protein diet during pregnancy and lactation on glucose and protein metabolism in soleus muscle isolated from adult male rats. Female rats were fed either a normal protein diet or low-protein diet during gestation and lactation. After weaning, all pups were fed a normal protein diet until the 210th day postpartum. In the 7th month of life, mass, contractile function, protein and glucose metabolism, and the Akt-mTOR pathway were measured in the soleus muscles of male pups. Dry weight and contractile function of soleus muscle in the low-protein diet group rats were found to be lower compared to the control group. Lipid synthesis was evaluated by measuring palmitate incorporation in white adipose tissue. Palmitate incorporation was higher in the white adipose tissue of the low-protein diet group. When incubated soleus muscles were stimulated with insulin, protein synthesis, total amino acid incorporation and free amino acid content, glucose incorporation and uptake, and glycogen synthesis were found to be reduced in low-protein diet group rats. Fasting glycemia was higher in the low-protein diet group. These metabolic changes were associated with a decrease in Akt and GSK-3ß signaling responses to insulin and a reduction in RPS6 in the absence of the hormone. There was also notably lower expression of Akt in the isolated soleus muscle of low-protein diet group rats. This study is the first to demonstrate how maternal diet restriction can reduce skeletal muscle protein and mass by downregulating the Akt-mTOR pathway in adulthood.

Anesthetic and sedative efficacy of essential oil of Hesperozygis ringens and the physiological responses of Oreochromis niloticus after biometric handling and simulated transport.

This study aimed to evaluate different concentrations of the essential oil of Hesperozygis ringens (EOHR) and its effects on anesthesia and transport of Oreochromis niloticus. Experiment I evaluated the concentrations of 0, 150, 300, 450, and 600 µL L-1 EOHR for times of induction and recovery from anesthesia and ventilatory frequency (VF) of O. niloticus (26 g), with 10 repetitions each in a completely randomized design. Based on the results of Experiment I, Experiment II submitted fish (25 g) to three treatments-control (clean water), ethanol (5 mL ethyl alcohol), and 600 µL L-1 EOHR-and then handling for biometry. Blood was collected 1 and 24 h after exposure and handling to analyze hematological and biochemical parameters in a completely randomized design in a factorial arrangement (3 × 2). Experiment III submitted fish (35 g) to simulated transport (4.5 h) with 0, 10, or 20 µL L-1 EOHR and determined the effects on blood variables. Concentrations of 450 and 600 µL L-1 EOHR provoked deep anesthesia in juvenile O. niloticus and provided induction and recovery times within the limits considered ideal for fish. However, this essential oil was not able to attenuate the effects of stress caused by biometric handling. EOHR was able to attenuate the effects of stress from simulated transport, with 10 µL L-1 EOHR being responsible for causing a decrease in protein, triglycerides, and cholesterol values immediately after transport of O. niloticus.

Hexamethylenetetramine-tridecanedioic acid (1/1): temperature-induced order-disorder structural phase transitions with phase co-existence.

The cocrystal hexamethylenetetramine-tridecanedioic acid (1/1) (HMT-C13), C6H12N4·C13H24O4, was investigated by single-crystal X-ray diffraction techniques at several temperatures during cooling and heating processes. Our results show the formation of two crystalline phases, separated by a large temperature phase co-existence between 290 and 340 K. Phase I, stable above 341 K, presents an orthorhombic structure described in the space group Bmmb, with one N4(CH2)6·C13H22O4 adduct in its asymmetric unit. Phase II, stable below 290 K, presents a monoclinic symmetry described by the space group P21/c, with two N4(CH2)6·C13H22O4 adducts in its asymmetric unit. The phase co-existence is observed both upon cooling and heating, and seems to be related to a complex domain-growth dynamic within the crystal.

Adverse events in critically ill patients: a cross-sectional study.

OBJECTIVE: To identify the prevalence of adverse events and the critically ill patient's need for care in an intensive care unit. METHOD: This is a cross-sectional study, carried out from January to March 2020. The adverse events investigated were pressure injury, accidental orotracheal extubation, fall, loss of central venous access, and healthcare-associated infection. The number of hours required for patient care was measured by the Nursing Activities Score. The categorical independent variables were described by absolute and relative frequencies, and the continuous ones, by central tendency. The magnitude measure was the odds ratio and a confidence interval of 95% was considered. RESULTS: of the 88 patients evaluated, 52.3% had adverse events, which were associated with a greater need for care, severity, and longer hospital stay. The mean Nursing Activities Score was 51.01% (12 h 24 min), with a deficit of 20% to 30% of nursing staff in the unit being identified. CONCLUSION: The prevalence of adverse events in the unit is high and the shortage of nursing staff in the unit revealed the need for adequate staffing to reduce the damage caused by the care provided to critically ill patients.

Rare case of low-grade fibromyxoid sarcoma of the thoracic wall with complete sternum reconstruction.

An 18-year-old boy presented with a giant midline mass with 9 years of evolution. The tumor was excised, and reconstruction made with a customized sternum implant and a free latissimus dorsi muscle flap with skin graft. Histological analysis was compatible with low-grade fibromyxoid sarcoma (LGFMS).

Toxicokinetics of silver in the goldfish Carassius auratus under simultaneous waterborne and diet-borne exposures to silver nanoparticles.

Silver nanoparticles (AgNPs) are applied in many products as antimicrobial agents and can be found in the environment. In this study, the uptake and elimination kinetics of silver nanoparticles in fish (Carassius auratus), via simultaneous water and dietary exposure, was investigated and compared with ionic silver (AgNO3). Silver concentration in the tissues of C. auratus after the uptake phase was similar between nanoparticles and ionic treatments. Upon exposure to nanoparticles, Ag concentration in the different tissues of C. auratus was significantly different (Ag[liver] > Ag[intestine] > Ag[gill] > Ag[muscle]). The liver presented the highest amount of Ag among all organs, and no elimination was detected throughout the elimination period. Our results suggest that once uptake of Ag occurs in fish, the elimination takes very long which may pose ecological implications for bioaccumulation.

Contralateral internal mammary vessels - a rescue recipient vessels option in breast reconstruction.

The most used vessels for free flap breast reconstruction are the internal mammary, the thoracodorsal and the circumflex scapular. We present a case where those were inadequate. DIEP vessels were passed through a created sternal groove and anastomosed to the contralateral IM vessels, accessed by the breast symmetrisation incisions.

Bioaccumulation but no biomagnification of silver sulfide nanoparticles in freshwater snails and planarians.

Bioaccumulation studies are critical in regulatory decision making on the potential environmental risks of engineered nanoparticles (NPs). The present study evaluated the toxicokinetics of silver, taken up from sulfide nanoparticles (Ag2S NPs; simulating an aged Ag NP form) and AgNO3 (ionic counterpart), in the pulmonate snail Physa acuta and the planarian Girardia tigrina. The snails were first exposed for 7 days to Ag-spiked water, along with the microalgae Raphidocelis subcapitata upon which they fed setting up a double route exposure, and subsequently provided as pre-exposed food to the planarians. Ag toxicokinetics and bioaccumulation were assessed in planarians and snails, and potential biomagnification from snail to planarian was evaluated. Gut depuration was also explored to understand whether it constitutes a factor likely to influence Ag toxicokinetics and internal concentrations in the test species. Both species revealed Ag uptake in Ag2S NP and AgNO3 treatments, with higher uptake from the latter. Uptake by the snails was probably via a combination of water exposure and ingested algae provided as food, but ingestion of algae possibly had higher relevance for Ag uptake from the Ag2S NPs compared to AgNO3. For planarians, diet probably was the most important exposure route since no Ag uptake was observed in previous waterborne exposures to Ag2S NPs. Kinetics and internal Ag concentrations did not significantly differ between depurated and non-depurated snails or planarians. The planarians fed on snails revealed no biomagnification. To the best of our knowledge this is the first study investigating the toxicokinetics and biomagnification of NPs in planarians, and with that providing important data on the kinetics and bioaccumulation of NPs in a relevant benthic species.