Online ascorbate sensing reveals oxidative injury occurrence in inferior colliculus in salicylate-induced tinnitus animal model.

Tinnitus is a widespread and serious clinical and social problem. Although oxidative injury has been suggested to be one of pathological mechanisms in auditory cortex, whether this mechanism could be applied to inferior colliculus remains unclear. In this study, we used an online electrochemical system (OECS) integrating in vivo microdialysis with selective electrochemical detector to continuously monitor the dynamics of ascorbate efflux, an index of oxidative injury, in inferior colliculus of living rats during sodium salicylate-induced tinnitus. We found that OECS with a carbon nanotubes (CNTs)-modified electrode as the detector selectively responses to ascorbate, which is free from the interference from sodium salicylate and MK-801 that were used to induce tinnitus animal model and investigate the N-methyl-d-aspartate (NMDA) receptor mediated excitotoxicity, respectively. With the OECS, we found that the extracellular ascorbate level in inferior colliculus significantly increases after salicylate administration and such increase was suppressed by immediate injection of NMDA receptor antagonist MK-801. In addition, we found that salicylate administration significantly increases the spontaneous and sound stimuli evoked neural activity in inferior colliculus and that the increases were inhibited by the injection of MK-801. These results suggest that oxidative injury may occur in inferior colliculus following salicylate-induced tinnitus, which is closely relevant to the NMDA-mediated neuronal excitotoxicity. This information is useful for understanding the neurochemical processes in inferior colliculus involved in tinnitus and its related brain diseases.

Effects of polystyrene nanoplastics on melanin interference toxicity and transgenerational toxicity of ethylhexyl salicylate based on DNA methylation sequencing.

Organic ultraviolet filters (OUVFs) are new hydrophobic organic pollutants in the aquatic environment. When ingested by aquatic organisms, OUVFs can induce a variety of toxic effects in organisms and be transferred to offspring. However, as the main active ingredient in sunscreens, OUVFs have rarely been investigated for their melanin interference toxicity or transgenerational toxic effects on aquatic organisms and their interactive toxic effects with nanoplastics (NPs). Here, we show the mechanism by which OUVFs interfere with melanogenesis in parental or offspring zebrafish and the effect of polystyrene (PS) NPs on the melanin-interference effect of OUVFs. We found that EHS induced significant enrichment of the melanogenesis pathway, inhibited the expression of the key melanin gene microphthalmia-associated transcription factor a (mitfa) and induced the mitf tyrosinase (tyr)-dopachrome tautomerase (dct)-tyrosinase related protein 1 (tyrp1) signaling cascade in parents, which ultimately induced a decrease in melanin content. After reproduction, transgenerational melanin interference effects of EHS may occur through the maternal inheritance of mitfa. Coexisting PS-NPs may inhibit the melanin interference toxicity or transgenerational toxicity of EHS by reducing ultraviolet irritation to the skin through adsorption of EHS. Our results demonstrate the ecotoxic potential of OUVFs in terms of melanin interference and the interference of PS-NP carrier effects on the toxicity of OUVFs. We anticipate that our assay will contribute to the assessment of the toxic effects of OUVFs and provide a basis for the interactive ecotoxicity assessment of PS-NPs and hydrophobic organic pollutants.

A critical review of ginkgolic acids in Ginkgo biloba leaf extract (EGb): toxicity and technologies to remove ginkgolic acids and their promising bioactivities.

Ginkgo biloba leaf extract (EGb) is high in bioactive components (over 170), which are used in food additives, medicine, cosmetics, health products, and other sectors. Nonetheless, ginkgolic acids (GAs) in Ginkgo biloba (GB) have been identified as the primary source of EGb's adverse effects such as embryotoxicity, cytotoxicity, neurotoxicity, and inhibition of enzyme systems. As a result, the Chinese, European, and United States pharmacopeias all mandate that the GA concentration in EGb be less than 5 µg g-1. This review looked at the toxicity of ginkgolic acid (from in vitro and in vitro trials) as well as the technologies (such as adsorption/desorption, enzymatic degradation, counter-current chromatography, liquid-liquid microextraction, dual-frequency ultrasonic-solvent extraction, deep eutectic solvent, etc.) used to lower the GA to the desired concentration. These technologies' advantages, disadvantages, viability, and future trends were compared. In addition, several pharmacological significances of GA extraction, such as anti-microbial, anti-inflammatory, anti-tumor, etc., were discussed, as well as future directions.

Nitric oxide signalling underlies salicylate-induced increases in neuronal firing in the inferior colliculus: A central mechanism of tinnitus?

The anti-inflammatory drug salicylate induces tinnitus in animals and man. Salicylate reduces cochlear output but causes hyperactivity in higher auditory centres, including the inferior colliculus (the auditory midbrain). Using multi-electrode recording in anaesthetised guinea pigs (Cavia porcellus), we addressed the hypothesis that salicylate-induced hyperactivity in the inferior colliculus involves nitric oxide signalling secondary to increased ascending excitatory input. Systemic salicylate (200 mg/kg i.p., 0 h) markedly increased spontaneous and sound-driven neuronal firing in the inferior colliculus (3-6 h post drug), with both onset and sustained responses to pure tones being massively increased. Reverse microdialysis of increasing concentrations of salicylate directly into the inferior colliculus (100 µM-10 mM, from 0 h) failed to mimic systemic salicylate. In contrast, it caused a small, transient, increase in sound-driven firing (1 h), followed by a larger sustained decrease in both spontaneous and sound-driven firing (2-5 h). When salicylate was given systemically, reverse microdialysis of the neuronal nitric oxide synthase inhibitor L-methyl arginine into the inferior colliculus (500 mM, 2-6 h) completely blocked the salicylate-induced increase in spontaneous and sound-driven neuronal firing. Our data indicate that systemic salicylate induces neuronal hyperactivity in the auditory midbrain via a mechanism outside the inferior colliculus, presumably upstream in the auditory pathway; and that the mechanism is ultimately dependent on nitric oxide signalling within the inferior colliculus. Given that nitric oxide is known to mediate NMDA receptor signalling in the inferior colliculus, we propose that salicylate activates an ascending glutamatergic input to the inferior colliculus and that this is an important mechanism underlying salicylate-induced tinnitus.

Melanin interference toxicity or transgenerational toxicity of organic UV filter ethylhexyl salicylate on zebrafish.

With the improvement of human health awareness, the production and usage of sunscreens have increased dramatically, and their active ingredients, organic ultraviolet (UV) filters (OUVFs), have the potential to induce melanin abnormalities in aquatic organisms due to their UV-absorbing properties as they enter the aquatic environment directly with the washing of skin during water activities. In this paper, the melanin interference toxicity or transgenerational toxicity effects of typical OUVFs ethylhexyl salicylate (EHS) on zebrafish (Danio rerio) were investigated based on transcriptomic sequencing technology. Results showed that EHS induced significant enrichment of the melanin-related pathway cAMP signaling pathway in parental skin tissue through UV absorption, with sensitive genes identified as melanocortin 1 receptor, protein kinase A catalytic subunit beta a, calcium/calmodulin-dependent protein kinase II delta 2, adenylate cyclase 1 and G protein subunit alpha I a. qRT-PCR verification results showed that EHS may inhibit the expression of the melanin master regulator microphthalmia-associated transcription factor a (mitfa) and its induced signaling cascade mitf-tyrosinase (tyr)-dopachrome tautomerase (dct)-tyrosinase related protein 1 (tyrp1) by inducing abnormal expression of the above sensitive genes, thereby reducing melanogenesis. After reproduction, the melanin interference effect of EHS on the parents can be carried over to offsprings through maternal inheritance of abnormally expressed mitfa and parental transfer of pollutants, as evidenced by significant enrichment of melanogenesis pathway, abnormal expression of sensitive genes mitfa, tyr, dct and tyrp1b and significant decreases in melanin content and spinal melanin area. These findings revealed the specific melanin interference toxicity of OUVFs with UV-absorbing properties, facilitating a comprehensive ecological risk assessment of OUVFs and providing scientific support for the management of new pollutants.

Effects of environmental concentrations of the fragrance amyl salicylate on the mediterranean mussel Mytilus galloprovincialis.

Amyl salicylate (AS) is a fragrance massively used as a personal care product and following the discharged in wastewaters may end up in the aquatic environment representing a potential threat for the ecosystem and living organisms. AS was recently detected in water of the Venice Lagoon, a vulnerable area continuously subjected to the income of anthropogenic chemicals. The lagoon is a relevant area for mollusc farming, including the Mediterranean mussels (Mytilus galloprovincialis) having an important economic and ecological role. Despite high levels of AS occurred in water of the Lagoon of Venice, no studies investigated the possible consequences of AS exposures on species inhabiting this ecosystem to date. For the first time, we applied a multidisciplinary approach to investigate the potential effects of the fragrance AS on Mediterranean mussels. To reach such a goal, bioaccumulation, cellular, biochemical, and molecular analyses (RNA-seq and microbiota characterization) were measured in mussels treated for 7 and 14 days with different AS Venice lagoon environmental levels (0.1 and 0.5 µg L-1). Despite chemical investigations suggested low AS bioaccumulation capability, cellular and molecular analyses highlighted the disruption of several key cellular processes after the prolonged exposures to the high AS concentration. Among them, potential immunotoxicity and changes in transcriptional regulation of pathways involved in energy metabolism, stress response, apoptosis and cell death regulations have been observed. Conversely, exposure to the low AS concentration demonstrated weak transcriptional changes and transient increased representation of opportunistic pathogens, as Arcobacter genus and Vibrio aestuarianus. Summarizing, this study provides the first overview on the effects of AS on one of the most widely farmed mollusk species.

Epigenetic mechanisms of DNA methylation in the transgenerational effect of ethylhexyl salicylate on zebrafish.

In this study, a 120-day whole-life cycle exposure and oviposition experiment on zebrafish with maternal and paternal mixed mating strategy was conducted to investigate the epigenetic mechanism of DNA methylation in ethylhexyl salicylate (EHS, 1, 10, 100 µg/L)-induced transgenerational effects. Results showed that EHS could induce the decrease of DNA methyltransferase 1 (DNMT1) activity and average global DNA methylation level in maternal parents and the increase of the above indexes in paternal parents, while the change of glycine N-methyltransferase activity was opposite to DNMT1. The average global DNA methylation levels were significantly increased in the offsprings of both parents exposed and father-only exposed to EHS, suggesting that EHS-induced epigenetic modifications may be stable and heritable. Hierarchical clustering analysis of promoter at different methylation sites showed that the DNA methylation pattern of offsprings were similar to that of the paternal parents, meaning that the offsprings may have inherited paternal DNA methylation pattern with eya2, pcdh2g5 and pcdh2g1 as key genes and lead to high locomotor activity in offsprings. KEGG pathway analysis showed that parental exposure to EHS may interfere with the central nervous system, insulin function system, melanogenesis system and the normal development of somatic axis of offsprings.

The increase in the degree of neural forward masking of cochlea following salicylate application.

BACKGROUND: High doses of salicylate are known to reduce cochlear response amplitude and raise threshold. However, its effect on the cochlear forward masking, reflecting temporal resolution, is still unclear. METHODS: The neural forward masking of cochlea was evaluated using double-tone stimulation. The first tone burst (5ms) was named the "masker" and the second tone burst (5 ms) was named the "probe". The frequency and intensity of the masker and probe were equal, and the masker-probe interval varied from 2 to 32 ms. The reduction (%) of the probe-evoked cochlear compound action potential caused by the addition of the masker tone was used to represent cochlear forward masking. The data obtained before and 2 h following the injection of sodium salicylate (250 mg/kg) were compared. RESULTS: The neural forward masking of cochlea in the normal rats increased as the masker-probe interval decreased. At 16 kHz, for example, it increased from ~5% to 32ms masker-probe interval to ~85% at 2ms masker-probe interval. Two hours post salicylate injection, the neural forward masking was significantly enhanced except at 32 ms masker-probe interval. Interestingly, this enhancement was only observed in the limited frequency range of 16-30 kHz. DISCUSSION: The enhancement of forward masking of cochlea following salicylate administration may reflect defective neurotransmitter release. This frequency-dependent injury in the cochlea may lead to the development of central plasticity observed after salicylate administration, likely through the increase in central gain, leading to perceptual consequences.

Cytotoxicity and genotoxicity of salicylate- and calcium silicate-based root canal sealers on primer human periodontal ligament fibroblasts.

The aim of this study was to evaluate the biocompatibility of epoxy-resin-based AHPlus, salicylate-based MTA-Fillapex and calcium silicate-based iRootSP root canal sealers. Cytotoxicity was assessed by XTT test. The extracts from sealers of different setting times were serially diluted. Cell viability was calculated as the percentage of the control group (100%). The optimal concentration of each sealer was used at genotoxicity test, and micronuclei formations were detected. Statistical analyses were done by using Kruskal-Wallis and Dunn post hoc test with Bonferroni correction. AHPlus and MTA-Fillapex showed the lowest percentage of cell viability at higher concentrations (1:1, 1:2, 1:4), especially at first 12 h. iRootSP showed higher viability at all concentrations and times than AHPlus and MTA-Fillapex. At genotoxicity assay, AHPlus increased the number of micronuclei. MTA-Fillapex slightly induced micronucleus formation (not significant) and iRootSP was not increased. In conclusion, calcium silicate-based iRootSP had lowest cytotoxic and genotoxic potential and can be considered as a highly biocompatible material.

Bismuth subsalicylate incorporated in polycaprolactone-gelatin membranes by electrospinning to prevent bacterial colonization.

Periodontitis is a chronic, multifactorial, inflammatory disease characterized by the progressive destruction of the periodontal tissues. Guided tissue regeneration (GTR), involving the use of barrier membranes, is one of the most successful clinical procedures for periodontal therapy. Nevertheless, rapid degradation of the membranes and membrane-related infections are considered two of the major reasons for GTR clinical failure. Recently, integration of non-antibiotic, antimicrobial materials to the membranes has emerged as a novel strategy to face the bacterial infection challenge, without increasing bacterial resistance. In this sense, bismuth subsalicylate (BSS) is a non-antibiotic, metal-based antimicrobial agent effective against different bacterial strains, that has been long safely used in medical treatments. Thus, the aim of the present work was to fabricate fibrillar, non-rapidly bioresorbable, antibacterial GTR membranes composed of polycaprolactone (PCL), gelatin (Gel), and BSS as the antibacterial agent. PCL-G-BSS membranes with three different BSS concentrations (2 wt./v%, 4 wt./v%, and 6 wt./v%) were developed by electrospinning and their morphology, composition, water wettability, mechanical properties, Bi release and degradation rate were characterized. The Cytotoxicity of the membranes was studiedin vitrousing human osteoblasts (hFOB) and gingival fibroblasts (HGF-1), and their antibacterial activity was tested againstAggregatibacter actinomycetemcomitans, Escherichia coli, Porphyromonas gingivalisandStaphylococcus aureus.The membranes obtained exhibited adequate mechanical properties for clinical application, and appropriate degradation rates for allowing periodontal defects regeneration. The hFOB and HGF-1 cells displayed adequate viability when in contact with the lixiviated products from the membranes, and, in general, displayed antibacterial activity against the four bacteria strains tested. Thus, the PCL-G-BSS membranes showed to be appropriate as potential barrier membranes for periodontal GTR treatments.

Rhabdomyolysis among hospitalized patients for salicylate intoxication in the United States: Nationwide inpatient sample 2003-2014.

INTRODUCTION: This study aimed to assess the risk factors and impact of rhabdomyolysis on treatments, outcomes, and resource utilization in hospitalized patients for salicylate intoxication in the United States. MATERIALS AND METHODS: The National Inpatient Sample was utilized to identify hospitalized patients with a primary diagnosis of salicylate intoxication from 2003-2014. Rhabdomyolysis was identified using hospital diagnosis code. We compared the clinical characteristics, in-hospital treatment, outcomes, and resource utilization between patients with and without rhabdomyolysis. RESULTS: A total of 13,805 hospital admissions for salicylate intoxication were studied. Of these, rhabdomyolysis developed in 258 (1.9%) admissions. The risk factors for rhabdomyolysis were age>20 years, male sex, volume depletion, hypokalemia, sepsis, and seizure. After adjustment for baseline clinical characteristics, salicylate intoxication patients with rhabdomyolysis required more invasive mechanical ventilation, and renal replacement therapy. Rhabdomyolysis was significantly associated with higher risk of failure of any organ systems, and in-hospital mortality. Length of hospital stay and hospitalization cost were higher when rhabdomyolysis occurred during hospital stay. CONCLUSIONS: Rhabdomyolysis was not common in hospitalized patients for salicylate intoxication but it was associated with increased morbidity, mortality, and resource utilization.

Risk of toxicity from pediatric topical salicylate ingestions.

INTRODUCTION: Suspected pediatric ingestions of greater than or equal to one teaspoon topical salicylate analgesic are recommended by poison control centers to be managed at healthcare facilities. This cutoff is applied for both liquid and non-liquid (cream, ointment, gel) formulations. METHODS: California poison control cases involving topical salicylate exposures in children less than 6-years-old who were evaluated at a health care facility between 2003 and 2018 were analyzed. RESULTS: Of 599 patient cases, the majority described no or minor symptoms, with gastrointestinal distress being the most common. Signs of salicylate toxicity (metabolic acidosis, tachypnea) occurred in six cases. Seven patients were hospitalized, six of whom were exposed to liquid preparations. DISCUSSION: In line with previous research, liquid salicylate preparations were more frequently associated with the signs of salicylate toxicity and hospitalization. CONCLUSION: There was a low frequency of severe side effects and low hospitalization rates among those referred to a healthcare facility, especially for non-liquid topical salicylate ingestions.

Employment of cytology for in vitro skin irritation test using a reconstructed human epidermis model, Keraskin™.

Skin irritation tests using reconstructed human epidermis (RhE) employ viability as an endpoint, but color interference or borderline results are often problematic. We examined whether the cytology of cells from treated RhE could determine skin irritancy. Six chemicals (three irritants; DnP, 1-B, PH, three non-irritants; DP, APA, HS) were evaluated in a RhE, Keraskin™. DP, HS, and PH were clearly classified with viability, but DnP, 1-B, and APA were often falsely determined, due to borderline values falling near the cutoff, 50%. In histology, the tissues treated with DnP, 1-B, and PH showed erosion of the stratum corneum, vacuolization, and necrosis in the basal layer. DP- and HS-treated tissues showed relatively normal morphology but APA induced necrosis similar to irritants. Cytology revealed that DnP, 1-B or PH depleted cells and induced irregular and abnormal cell shapes. In contrast, relatively regular and normal shapes and clear distinction between the nucleus and cytoplasm was observed for DP, APA and HS. To further confirm it, additional 10 substances, including false positives from OECD TG 439, were tested. Overall (16 substances in total), cytology: total area predicted the skin irritancy of test chemicals with the highest accuracy (87.5%) followed by cytology: cell count (81.3%), histology (75%) and viability (68.8%), confirming the utility of cytology as an alternative endpoint in the skin irritation test using RhE.