Concentration-dependent Toxicity Research Articles

Effects of copper oxide nanoparticles on the Chlorella algae in the presence of humic acid

Utilization of nano compounds has greatly increased the discharge of these compounds into the environment, and has increased the possible risk to human health and environment. The aim of this study was to investigate the possible toxic effects of copper oxide nanoparticles on the Chlorella algae in the presence of dissolved and surface-bound humic acid. Chlorella cells were left to grow in the culture media containing copper oxide nanoparticles and HA in different treatments. After specified contact times, the number of algae and Reactive Oxygen Species were daily measured. The results showed that the copper oxide nanoparticles and HA (individually) had a concentration-dependent toxicity on Chlorella algae and these compounds with high concentrations increase the amount of intracellular ROS and decrease the growth rate of Chlorella algae. The LC50 of copper oxide nanoparticles and HA was 2.7 mg/l and 25 mg/l respectively. Dissolved HA in mixture with copper oxide nanoparticles intensified the nanotoxicity by reducing the relative growth rate and increasing the reactive oxygen species. The ROS values reached to 315% and 340% in the experiments with 16 mg/l CuONP + 16 mg/l dissolved HA and 16 mg/l CuONP + 32 mg/l dissolved HA (respectively) compared to the blank controls. The relative growth rate scaled up with increasing the HA content of the complexes of CuONP–HA (surface-bound HA).

Toxicity Mechanism of Gadolinium Oxide Nanoparticles and Gadolinium Ions in Human Breast Cancer Cells.

Due to the potential advantages of Gadolinium Nanoparticles (NPs) over gadolinium elements, gadolinium based NPs are currently being explored in the field of MRI. Either in elemental form or nanoparticulate form, gadolinium toxicity is believed to occur due to the deposition of gadolinium ion (designated as Gd3+ ion or simply G ion). There is a serious lack of literature on the mechanisms of toxicity caused by either gadolinium-based NPs or ions. Breast cancer tumors are often subjected to MRIs, therefore, human breast cancer (MCF-7) cells could serve as an appropriate in vitro model for the study of Gadolinium Oxide (GO) NP and G ion. Cytotoxicity and oxidative damage was determined by quantifying cell viability, cell membrane damage, and Reactive Oxygen Species (ROS). Intracellular Glutathione (GSH) was measured along with cellular Total Antioxidant Capacity (TAC). Autophagy was determined by using Monodansylcadaverine (MDC) and Lysotracker Red (LTR) dyes in tandem. Mitochondrial Membrane Potential (MMP) was measured by JC-1 fluorescence. Physicochemical properties of GO NPs were characterized by field emission transmission electron microscopy, X-ray diffraction, and energy dispersive spectrum. A time- and concentration-dependent toxicity and oxidative damage was observed due to GO NPs and G ions. Bax/Bcl2 ratios, FITC-7AAD double staining, and cell membrane blebbing in phase-contrast images all suggested different modes of cell death induced by NPs and ions. In summary, cell death induced by GO NPs with high aspect ratio favored apoptosis-independent cell death, whereas G ions favored apoptosis-dependent cell death.

An across-species comparison of the sensitivity of different organisms to Pb-based perovskites used in solar cells

Organic–inorganic perovskite solar cells (PSCs) are promising candidates as photovoltaic cells. Recently, they have attracted significant attention due to certified power conversion efficiencies exceeding 23%, low–cost engineering, and superior electrical/optical characteristics. These PSCs extensively utilize a perovskite–structured composite with a hybrid of Pb-based nanomaterials. Operation of them may cause the release of Pb-based nanoparticles. However, limited information is available regarding the potential toxicity of Pb-based PSCs on various organisms. This study conducted a battery of in vitro and in vivo toxicity bioassays for three quintessential Pb-based PSCs (CH3NH3PbI3, NHCHNH3PbBr3, and CH3NH3PbBr3) using progressively more complex forms of life. For all species tested, the three different perovskites had comparable toxicities. The viability of Caco–2/TC7 cells was lower than that of A549 cells in response to Pb-based PSC exposure. Concentration–dependent toxicity was observed for the bioluminescent bacterium Vibrio fischeri, for soil bacterial communities, and for the nematode Caenorhabditis elegans. Neither of the tested Pb-based PSCs particles had apparent toxicity to Pseudomonas putida. Among all tested organisms, V. fischeri showed the highest sensitivity with EC50 values (30 min of exposure) ranging from 1.45 to 2.91 mg L-1. Therefore, this study recommends that V. fischeri should be preferably utilized to assess.PSC toxicity due to its increased sensitivity, low costs, and relatively high throughput in a 96–well format, compared with the other tested organisms. These results highlight that the developed assay can easily predict the toxic potency of PSCs. Consequently, this approach has the potential to promote the implementation of the 3Rs (Replacement, Reduction, and Refinement) principle in toxicology and decrease the dependence on animal testing when determining the safety of novel PSCs.

Evaluation of the Effect of CYP2D6 Genotypes on Tramadol and O-Desmethyltramadol Pharmacokinetic Profiles in a Korean Population Using Physiologically-Based Pharmacokinetic Modeling.

Tramadol is a μ-opioid receptor agonist and a monoamine reuptake inhibitor. O-desmethyltramadol (M1), the major active metabolite of tramadol, is produced by CYP2D6. A physiologically-based pharmacokinetic model was developed to predict changes in time-concentration profiles for tramadol and M1 according to dosage and CYP2D6 genotypes in the Korean population. Parallel artificial membrane permeation assay was performed to determine tramadol permeability, and the metabolic clearance of M1 was determined using human liver microsomes. Clinical study data were used to develop the model. Other physicochemical and pharmacokinetic parameters were obtained from the literature. Simulations for plasma concentrations of tramadol and M1 (after 100 mg tramadol was administered five times at 12-h intervals) were based on a total of 1000 virtual healthy Koreans using SimCYP® simulator. Geometric mean ratios (90% confidence intervals) (predicted/observed) for maximum plasma concentration at steady-state (Cmax,ss) and area under the curve at steady-state (AUClast,ss) were 0.79 (0.69–0.91) and 1.04 (0.85–1.28) for tramadol, and 0.63 (0.51–0.79) and 0.67 (0.54–0.84) for M1, respectively. The predicted time–concentration profiles of tramadol fitted well to observed profiles and those of M1 showed under-prediction. The developed model could be applied to predict concentration-dependent toxicities according to CYP2D6 genotypes and also, CYP2D6-related drug interactions.

Developing green insecticides to manage olive fruit flies? Ingestion toxicity of four essential oils in protein baits on Bactrocera oleae

Effective and eco-friendly plant-borne insecticides for developing lure and kill control tools against tephritid flies are scarce. Herein, the activity of four essential oils (EOs) obtained from two Apiaceae, Pimpinella anisum L. and Trachyspermum ammi (L.) Sprague, and two Lamiaceae, Thymbra spicata L. and Ocimum gratissimum L., was evaluated against the olive fruit fly, Bactrocera oleae (Rossi), a key pest of olive groves. The EO chemical composition was determined by gas chromatography coupled with mass spectrometry (GC-MS) analyses. The four EOs incorporated in protein baits were tested for ingestion toxicity on B. oleae adults, mimicking lure and kill assays. Results showed concentration-dependent toxicity, with mortality rates ranging from 6.5% (P. anisum EO at 0.03% w/v concentration) to 100% (P. anisum EO at 0.5% w/v concentration, T. ammi EO at 1% w/v). The best efficacy was achieved by EOs from T. ammi and P. anisum, showing LC50 values of 633 ppm and 771 ppm, respectively, far encompassing currently published findings on the ingestion toxicity of EOs on tephritid adults. Thymol (58.3%), p-cymene (24.7%) and γ-terpinene (14.2%), and (E)-anethole (98.3%) were the major constituents of T. ammi and P. anisum EOs, respectively. Thymol (57.0%), p-cymene (12.4%) and γ-terpinene (6.9%), and carvacrol (41.4%) and p-cymene (41.2%) were the predominant components in O. gratissimum and Th. spicata EOs, respectively. Further field research on the efficacy of these EOs incorporated in food baits against the olive fruit fly is ongoing to boost their real-world application, contributing to develop alternative tools for the sustainable management of B. oleae.

Phytotoxic effect of silver nanoparticles on seed germination and growth of terrestrial plants

Silver nanoparticles (AgNP) exhibit size and concentration dependent toxicity to terrestrial plants, especially crops. AgNP exposure could decrease seed germination, inhibit seedling growth, affect mass and length of roots and shoots. The phytotoxic pathway has been partly understood. Silver (as element, ion or AgNP) accumulates in roots/leaves and triggers the defense mechanism at cellular and tissue levels, which alters metabolism, antioxidant activities and related proteomic expression. Botanical changes (either increase or decrease) in response to AgNP exposure include reactive oxygen species generation, superoxide dismutase activities, H2O2 level, total chlorophyll, proline, carotenoid, ascorbate and glutathione contents, etc. Such processes lead to abnormal morphological changes, suppression of photosynthesis and/or transpiration, and other symptoms. Although neutral or beneficial effects are also reported depending on plant species, adverse effects dominate in majority of the studies. More in depth research is needed to confidently draw any conclusions and to guide legislation and regulations.

Cytotoxicity of hyaluronic acid coated chitosan nanoparticles containing nitric oxide donor against cancer cell lines

The incidence and mortality rates of all types of cancer have a global burden. The lack of specificity of chemotherapy is one of the major problems in cancer treatment and it is related with moderate to severe adverse effects. CD44 is a protein overexpressed in certain types of cancer cells and can be used as an anchor of attachment for nanoparticles decorated with hyaluronic acid (HA). HA is a natural polymer with high affinity for CD44 receptors. In this work, chitosan nanoparticles (CS NPs) were coated with HA to delivery nitric oxide (NO) donor to cancer cells. NO is a small molecule involved in several physiological processes and it has cytotoxicity against cancer cells. HA-coated and uncoated NO-releasing CS NPs were synthesized and characterized by different techniques. Uncoated and HA-coated NO-releasing CS NPs have hydrodynamic diameters of 142.80 ± 2.22 nm and 170.80 ± 0.14 nm, respectively, polydispersity index of 0.282 ± 0.010 and 0.37 ± 0.04, respectively, and a zeta potential values of + 25.20 ± 0.85 mV and + 15.60 ± 0.15 mV, respectively. As expected, the presence of HA layer on the surface of NO-releasing CS NPs increased hydrodynamic size ca. 20%. The encapsulation efficiency of the NO donor into CS NPs was found to be higher than 90%. The kinetic of NO release from uncoated and HA-coated CS NPs has two distinct phases, an initial burst followed by the establishment of a plateau, with a maximum of NO released at 40 mmol·L−1. At this concentration, NO is expected to have cytotoxic effects. The cytotoxicity of uncoated and HA-coated NO releasing CS NPs showed a concentration-dependent toxicity against human prostatic carcinoma (PC-3) and human uterine cervix carcinoma (HeLa) cell lines. Taken all together, uncoated and HA-coated NO-releasing CS NPs might find important biomedical applications, including cancer in treatment.

Evaluation the potential of indigenous biocontrol agent Trichoderma harzianum and its interactive effect with nanosized ZnO particles against the sunflower damping-off pathogen, Rhizoctonia solani

Rhizoctonia solani is a phytopathogenic fungus affecting a wide range of plants hosts including the sunflower causing various diseases such as damping-off. Current management approaches of this pathogen are inadequate. Aim of this study was to assess the potential of eco-friendly control methods, the indigenous biocontrol fungus Trichoderma harzianum and ZnO nanoparticles for controlling of the sunflower damping-off pathogen, R. solani. The biocontrol agent T. harzianum showed a high antagonism effect on R. solani growth. Additionally, growth of R. solani was significantly (p = 0.01) reduced gradually by presence of various concentrations of the ZnO NPs indicating to concentration-dependent toxicity effect. However, a similar impact was also observed on growth of T. harzianum. On the other hand, the percentage of seed germination and stem length of sunflower (Coban cv.) did not affect significantly by ZnO NPs. Conversely, the root lengths were significantly decreased. In the horticultural canopy trial, the best reduction to the sunflower damping-off incidence percentage was achieved by treatment of sunflower seedlings growing in compost inoculated with T. harzianum and R. solani 68.75% comparing to 100% in the control. In contrast, a significant reduction in severity percentage of damping-off symptoms was accomplished in most of the treatments. The best suppression was achieved in treatments of spraying the seedlings with ZnO NPs (15 mg/ml) in two days prior of planting that was 50% in compression with 97.50% in control. These findings can justify the application of the local biocontrol agent T. harzianum alone or in integration with ZnO NPs to be included with current management approaches of sunflower damping-off, which could lead to a diminution in the utilizing of fungicides.

Toxicity assessment of magnesium oxide nano and microparticles on cancer and non-cancer cell lines

Testing of magnesium oxide nanoparticles (MgO NPs) on established cell lines at cellular levels using toxicological endpoints provide valuable information about their adverse effects upon exposure. In vitro toxicity assessment of MgO NPs and their microparticles was carried out at 50, 100, 200 and 400 µg/mL concentrations by using cytotoxicity, genotoxicity, oxidative stress, cellular apoptosis and cellular uptake studies in cancer (HepG2) and non-cancer (NRK 49F) cell lines after 24 h of treatment. IC50 concentration for MgO NPs was found to be > 400 µg/mL in both cell lines after 24 h treatment. A concentration dependent toxicity was noted in genotoxic studies and oxidative stress parameters. A significant increase in the comet tail DNA was recorded at 200 and 400 µg/mL concentrations of MgO NPs when compared with controls in HepG2 and NRK 49F cells. Exposure to MgO NPs led to an increase in the generation of reactive oxygen species (ROS) in both the cell types. Genotoxicity results were further supported by apoptotic analysis. MgO particles were found adhered to the cell membrane when assayed by ICP-OES. The results of this study showed that the MgO NPs were toxic at high concentrations only. Furthermore, MgO NPs are more toxic to cancerous cells compared to non-cancerous cells. ROS mediated genotoxicity was observed when treated with MgO NPs. The current study adds to the information on MgO particles. The results of this investigation may help in advancement of understanding of toxicological nature of MgO NPs and aid in their use.

Structure-cytotoxicity relationship profile of 13 synthetic cathinones in differentiated human SH-SY5Y neuronal cells

Synthetic cathinones also known as β-keto amphetamines are a new group of recreational designer drugs. We aimed to evaluate the cytotoxic potential of thirteen cathinones lacking the methylenedioxy ring and establish a putative structure-toxicity profile using differentiated SH-SY5Y cells, as well as to compare their toxicity to that of amphetamine (AMPH) and methamphetamine (METH). Cytotoxicity assays [mitochondrial 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) reduction and lysosomal neutral red (NR) uptake] performed after a 24-h or a 48-h exposure revealed for all tested drugs a concentration-dependent toxicity. The rank order regarding the concentration that promoted 50 % of toxicity, at 24 h exposure, by the MTT assay was: 3,4-dimethylmethcathinone (3,4-DMMC) > METH > mephedrone ≈ α-pyrrolidinopentiophenone > AMPH ≈ methedrone > pentedrone > buphedrone ≈ flephedrone >α-pyrrolidinobutiophenone > methcathinone ≈ N-ethylcathinone >α-pyrrolidinopropiophenone >N,N-dimethylcathinone ≈ amfepramone. Apoptotic cell death signs were seen for all studied cathinones. 3,4-DMMC, methcathinone and pentedrone triggered autophagy activation, as well as increased reactive oxygen species production, and N-acetyl-L-cysteine (NAC) totally prevented that rise. Importantly, NAC was also able to prevent the cytotoxicity promoted by 6 tested drugs, ruling for an involvement of oxidative stress in the toxic events observed. The increased lipophilic chain on the alpha carbon, the presence and the high steric volume occupied by the substituents on the aromatic ring, and the substitution of the pyrrolidine ring by its secondary amine analogue have proved to be key points for the cytotoxicity profile of these cathinones. The structure-toxicity relationship established herein may enlighten future human relevant mechanistic studies, and future clinical approaches on intoxications.

RETRACTED: In vitro and in vivo evaluation of degradation, toxicity, biodistribution, and clearance of silica nanoparticles as a function of size, porosity, density, and composition

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the corresponding author. Subsequent to the publication of the article Journal of Controlled Release 311–312 (2019) 1–15, in follow up studies in 2021, the corresponding author's lab members noticed significant discrepancies in reproducibility of some of the results reported in this manuscript. A detailed investigation in the lab was launched, and by retrieving the raw data available at the core facility pertaining to this manuscript, the following discrepancies were discovered that provide the basis for this retraction. These discrepancies have been reported to the University of Utah Research Integrity and Compliance Office by the corresponding author. The co-authors have been made aware of these discrepancies and of the decision of the corresponding author to retract. The corresponding author believes that the subject matter of this article, detailed analysis of the degradation of silica nanoparticles as a function of their physicochemical properties in relevant biological media in vitro, and in vivo, is significant. For successful utility of these particles in drug delivery applications their detailed biological fate needs to be examined. The significant discrepancies and lack of reproducibility of the reported data however is very unfortunate and the author hopes that this does not cast a doubt on the need for more detailed examination of the biological fate of silica nanoparticles in the future for their successful application in controlled release. In Vitro Data (Fig. 3) • Actual dissolution reaction volume was 2.5mL (confirmed by reviewing the lab notebook of the first author during the investigation) vs 3.5mL reported in the manuscript. • Sample volume was not used in the calculation to convert Inductively Coupled Plasma Mass Spectrometry (ICPMS) data to mg of silicon retrieved which is needed to calculate % degradation (needed to multiply data by 0.1 due to 0.1mL sample volumes). • Our investigation revealed a 20% “matrix effect with fluids” was communicated by ICPMS core facility person to the first author that was not addressed in the manuscript. • All data is different when calculating % degradation, not just by a factor of 10 due to not calculating for the 100ml sample volume. • Raw data during our investigation after publication, obtained from ICPMS facility, and not noted in the lab notebook, for day 28 of simulated lysosomal fluid (SLF) reveals n=1 and no data points for Stober100. In the manuscript however, error bars are shown for all particles at this time point and for the data for Stober100. Intracellular Degradation (Fig. 5) • Extremely high background with control causing negative % degradation for Disulfide Meso 100 from retrieved ICPMS data from core facility after publication, but manuscript shows ~1.25% degradation. • All other calculated % degradation based on retrieved data from ICPMS facility during the investigation after publication, do not match reported data in the paper. • Paper claims n=6, but raw data received from ICPMS facility during investigation (after publication) is clearly n=3. In Vivo Degradation (Fig. 6) ICPMS data retrieved during the investigation after publication for control mice showed extremely high background, and probably were not used in the calculations reported in this manuscript because it would have led to negative silicon contents for a few samples. Urine ICPMS data from the core facility was not available during investigation after publication, and cannot be retrieved from the first author's lab notebook. Hence its validity cannot be ascertained. There may be other discrepancies in the manuscript that have gone unnoticed. However, the Editor-in-Chief agrees that the above is significant enough to warrant retraction of the manuscript.

Atorvastatin induces mitochondrial dysfunction and cell apoptosis in HepG2 cells via inhibition of the Nrf2 pathway.

Atorvastatin (ATO) is a 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor widely used to treat hypercholesterolemia. However, clinical application is limited by potential hepatotoxicity. Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a master regulator of cellular antioxidants, and oxidative stress is implicated in statin-induced liver injury. This study investigated mechanisms of ATO-induced hepatotoxicity and potential mitigation by Nrf2 signaling. ATO reduced Nrf2 and antioxidant enzyme superoxide dismutase-2 (SOD2) expression in human hepatocarcinoma HepG2 cells. ATO also induced concentration-dependent HepG2 cell toxicity, reactive oxygen species (ROS) accumulation, and mitochondrial dysfunction as evidenced by decreased mitochondrial membrane potential (MMP) and cellular adenosine triphosphate (ATP). Further, ATO induced mitochondria-dependent apoptosis as indicated by increased Bax/Bcl-2 ratio, cleaved caspase-3, mitochondrial cytochrome c release and Annexin V-fluorescein isothiocyanate/propidium iodide staining. Tert-butylhydroquinone enhanced Nrf2 and SOD2 expression, and partially reversed ATO-induced cytotoxicity, ROS accumulation, MMP reduction, ATP depletion and mitochondria-dependent apoptosis. In conclusion, the present study demonstrates that ATO induces mitochondrial dysfunction and cell apoptosis in HepG2 cells, at least in part, via inhibition of the Nrf2 pathway. Nrf2 pathway activation is a potential prevention for ATO-induced liver injury.

Concentration-dependent effects of 17β-estradiol and bisphenol A on lipid deposition, inflammation and antioxidant response in male zebrafish (Danio rerio)

Environmental estrogenic compounds are important pollutants, which are widely distributed in natural water bodies. They produce various adverse effects on fish, but their concentration-dependent toxicities in fish metabolism and health are not fully understood. This study investigated the effects of 17β-estradiol (E2) and bisphenol A (BPA) at low and high concentrations on lipid deposition, inflammation and antioxidant response in male zebrafish. We measured fish growth parameters, gonad development, lipid contents and the activities of inflammatory and antioxidant enzymes, as well as their mRNA expressions. All E2 and BPA concentrations used increased body weight, damaged gonad structure and induced feminization in male zebrafish. The exposure of zebrafish to E2 and BPA promoted lipid accumulation by increasing total fat, liver triglycerides and free fatty acid contents, and also upregulated lipogenic genes expression, although they decreased total cholesterol content. Notably, zebrafish exposed to low concentrations of E2 (200 ng/L) and BPA (100 μg/L) had higher lipid synthesis and deposition compared to high concentrations (2000 ng/L and 2000 μg/L, respectively). However, the high concentrations of E2 and BPA increased inflammation and antioxidant response. Furthermore, BPA caused greater damage to fish gonad development and more severe lipid peroxidation compared to E2. Overall, the results suggest that the toxic effects of E2 and BPA on zebrafish are concentration-dependent such that, the relative low concentrations used induced lipid deposition, whereas the high ones caused adverse effects on inflammation and antioxidant response.

Differential in vivo hemocyte responses to nano titanium dioxide in mussels: Effects of particle size

Titanium dioxide nanoparticles (TiO2 NPs) are widely used in various products and inevitably released with different sizes and forms into aquatic environment. The purpose of this study was to assess the differential immune toxicity of TiO2 NPs with size difference on mussel hemocytes using flow cytometry (FCM) assays. Hemocyte parameters, including total hemocyte count (THC), hemocyte mortality (HM), phagocytosis activity (PA), lysosomal content (LC), esterase activity (EA), mitochondrial number (MN), mitochondrial membrane potential (MMP) and reactive oxygen species content (ROS) were evaluated in the mussels Mytilus coruscus exposed to two types of TiO2 NPs (25nm & 100nm: 0.1, 1, 10 mg/L, respectively). In general, size- and concentration-dependent toxicity was pronounced with 25nm-NP and highest concentration (10mg/L) being the most toxic. Alhough a slight recovery from the TiO2 exposure was observed, significant carry-over effects were still detected. These results highlight the importance of differential size effects of metal oxide NPs on toxicity mechanisms in aquatic animals.

Influence of formulation parameters on encapsulation of doxycycline in PLGA microspheres prepared by double emulsion technique for the treatment of periodontitis

Advanced therapeutics often employ controlled release of pharmaceutics by the use of microspheres. However, common techniques to produce microspheres suffer from poor encapsulation efficiency (EE) of hydrophilic drugs. The aim of this study was to assess various formulation parameters to enhance doxycycline (DOX) encapsulation into poly(D, L-lactide-co-glycolide) (PLGA) microspheres prepared by double emulsion (water/oil/water) solvent evaporation technique. The parameters included variations in co-solvents, external aqueous phase (W2) pH, and PLGA end-groups (ester- or acid-terminated). Results showed that the formulated microspheres sized <10 μm and were of low polydispersity. Furthermore, an external phase pH of 9.0 was most suitable for the incorporation of the drug. Additionally, the replacement of the polymer phase with a co-solvent system (1:5, EtOH:DCM %) significantly enhanced the drug EE using acid-terminated PLGA polymer. Drug release kinetics showed an initial burst release phase, followed by a controlled exponential phase that lasted up to 21 days. Furthermore, in vitro studies revealed concentration-dependent toxicity using periodontal ligament cells (PDLCs) and antibacterial properties against periodontal pathogens. Overall, this study demonstrated the optimal formulation parameters needed to achieve a high encapsulation of water-soluble drug into PLGA microspheres using emulsification techniques.

Lead-induced heat shock protein (HSP70) and metallothionein (MT) gene expression in the embryos of African catfish Clarias gariepinus (Burchell, 1822)

Abstract The enhanced expression of heat shock proteins (HSPs) and metallothionein (MT) can be detected in response to many environmental stressors, including exposure to heavy metals. We identified partial mRNA sequences for beta2-microglobulin (s2m), heat shock cognate 70 kDa protein (HSP70), and MT in embryos of the African catfish Clarias gariepinus (Burchell, 1822). Levels of these transcripts were assessed using reverse-transcription quantitative polymerase chain reaction (RT-QPCR) after embryos of various stages were exposed to different concentrations of lead nitrate. s2m gene expression exhibited a continuous increase over time. Neither HSP70 nor MT were upregulated, supporting the well-known sensitivity of these organisms to environmental pollutants. Interestingly, the partial MT and HSP70 mRNA sequences revealed an intimate phylogenetic relationship with these proteins in siluriforms. These partial sequences were more closely related to salmoniform proteins than to cypriniform proteins. The expression levels of HSP70 and MT were lower in embryonic tissues exposed to high concentrations of lead (500 µg/L), which impaired the fish's coping strategy via toxication at the cellular level. In conclusion, early developmental stages appear to be particularly vulnerable to lead and fail to activate the typical coping mechanisms. Therefore, these early life stages may not be suitable to characterize concentration-dependent toxicity.

Important pharmacogenomic aspects in the management of HIV/AIDS

In managing HIV/AIDS with highly active antiretroviral agents, the historical therapeutic aim remains to maintain the plasma concentrations at a level above the half maximal inhibitory concentration (IC50) required for 50% inhibition in viral replication. Concentration dependent toxicity is often observed in patients with elevated drug exposure and high peak plasma levels in lieu of accurately calculated drug dosages. Similarly low plasma concentrations are frequently witnessed in individuals receiving adequate dosage regimens. Pharmacogenetic variations in drug metabolizing enzymes may contribute to this phenomenon. Over the last decade, knowledge about the role of pharmacogenetics in the treatment and prediction of ARV plasma levels have increased significantly. However, the extent of these genetic variations remain largely unknown in the South African population, which has sparked a renewed enthusiasm for local pharmacogenetic studies.

Poly(ester amide) particles for controlled delivery of celecoxib.

Many potential pharmacological treatments for osteoarthritis can result in undesirable side effects due to the systemic administration of drugs, making the direct delivery of drugs to joints an attractive alternative. Poly(ester amide)s (PEAs) have been shown to exhibit promising properties for the development of particle-based intra-articular delivery vehicles. However, a limited range of PEA structures has been investigated. In this study, we prepared and characterized the properties of two different PEA particles composed of l-phenylalanine, sebacic acid, and either 1,4-butanediol or 1,8-octanediol (PBSe and POSe, respectively). The anti-inflammatory drug celecoxib (CXB) was encapsulated into the particles. Despite minor structural differences, PBSe and POSe exhibited different thermal and mechanical properties, and encapsulation of CXB influenced these properties. PBSe-CXB particles provided a slower release of drug in vitro relative to POSe-CXB. Toxicity studies showed that particles without drug exhibited low toxicity to ATDC5 and C2C12 cells, while the PBSe-CXB particles exhibited concentration-dependent toxicity. Host response to the particles was evaluated in an ovine model. No adverse effects were observed following intra-articular injection and it was observed that the particles diffused into the surrounding tissues. This work shows the importance of structural tuning in PEA delivery vehicles and demonstrates their potential for further development. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1235-1243, 2019.

Dispersible hydrolytically sensitive nanoparticles for nasal delivery of thyrotropin releasing hormone (TRH)

Nose-to-brain delivery of drugs is affected by nanoparticles (NPs) deposited on the olfactory surface and absorbed directly into the brain. Thyrotropin releasing hormone (TRH), a water soluble drug used for treating suicidal patients, was incorporated into a fast degrading poly(sebacic anhydride) (PSA) NPs. NPs were prepared by a solvent-antisolvent process under strict anhydrous environment to obtain high TRH loading and to avoid premature PSA degradation and TRH release. PSA and TRH were dissolved in a mixture of dichloromethane and ethanol and added dropwise to a dispersion of mannitol particles in heptane as an antisolvent. Mannitol powder was included in the antisolvent, so that formed NPs adhered to the mannitol microparticles for easy isolation and immediate dispersion in water prior to use. The size, surface charge, and morphology of the TRH-PSA NPs were determined using dynamic light scattering (DLS), zeta-potential, and Scanning Electron Microscopy (SEM), respectively. The NPs prepared were uniform and spherical of ~250 nm. Further, the in vitro release profile of TRH from NPs lasted for 12 h with most TRH released within the first hour in water. Concentration dependent cell toxicity studies revealed low toxicity level at low concentrations of the NPs. Surface adsorption of the NPs was also uniform on the cell surface as examined through the odyssey near infrared fluorescence (NIR) images using Indocyanine green (ICG). The NPs are designed to enable direct delivery to the olfactory epithelium using a refillable nasal atomizer that deposits mist onto the olfactory neuro-epithelium.

Metabolic perturbation, proliferation and reactive oxygen species jointly contribute to cytotoxicity of human breast cancer cell induced by tetrabromo and tetrachloro bisphenol A

Halogenated bisphenol A analogues (X-BPA) have been widely used in industrial production, such as flame retardant. Although BPA exposure was found to result in cytotoxicity, toxicity of X-BPA and molecular mechanism remain under-explored. In this study, we employed human breast cancer cell as a model to investigate the concentration-dependent toxicity and underlying mechanisms of tetrabromo bisphenol A (TBBPA) and tetrachloro bisphenol A (TCBPA). An integrated method involving molecular toxicology and mass spectrometry (MS)-based global metabolomics was applied to evaluate the toxicity of TCBPA and TBBPA on cell viability, reactive oxygen species (ROS), and metabolic alterations. The results demonstrated that low micromolar levels (0–10 μM) of TCBPA/TBBPA exposure induced cell proliferation and activated the energy metabolism of both glycolysis and amino acid. On the other hand, high micromolar levels (10–50 μM) of TCBPA/TBBPA exposure perturbed the balance between ROS and antioxidative defense process by promoting the ROS generation via the down-regulation of glutathione biosynthesis and up-regulation of nucleotide metabolism. This study, for the first time, provides evidence and mechanism for better understanding the cytotoxicity of TCBPA and TBBPA by regulating the specific metabolic pathways.