Mercury and selenium concentrations in lanugo of free-ranging California sea lions in the southern Gulf of California, Mexico

Total mercury ([THg]) and selenium ([TSe]) concentrations were determined in California sea lion (Zalophus californianus) lanugo from the Gulf of California in 2021 and 2022. Relationships with sex, morphometrics, and year were evaluated. Following toxicological thresholds of concern for piscivorous mammals, most pups had a [THg] < 10 ppm, one pup (2021) had a [THg] > 20 ppm, no pups had a [THg] > 30 ppm. Females had significantly higher [TSe] than males; sex did not influence [THg]. [THg] and [TSe] in 2022 were significantly higher in the general population and male cohorts compared to 2021. Significant negative correlations were observed between [THg], [TSe], and morphometrics (2021). These results indicate that, compared to other pinniped species, regional California sea lions may have a decreased likelihood of experiencing Hg-related adverse health effects. Year-related changes in element concentrations suggest continued monitoring of this population to assess pinniped, environmental, and potentially, human health.

Turbidity and Total Suspended Solids on the Lower Cache River Watershed, AR

The Cache River Watershed (CRW) in Arkansas is part of one of the largest remaining bottomland hardwood forests in the US. Although wetlands are known to improve water quality, the Cache River is listed as impaired due to sedimentation and turbidity. This study measured turbidity and total suspended solids (TSS) in seven sites of the lower CRW; six sites were located on the Bayou DeView tributary of the Cache River. Turbidity and TSS levels ranged from 1.21 to 896 NTU, and 0.17 to 386.33 mg/L respectively and had an increasing trend over the 3-year study. However, a decreasing trend from upstream to downstream in the Bayou DeView tributary was noted. Sediment loading calculated from high precipitation events and mean TSS values indicate that contributions from the Cache River main channel was approximately 6.6 times greater than contributions from Bayou DeView. Land use surrounding this river channel affects water quality as wetlands provide a filter for sediments in the Bayou DeView channel.

Novel Nitrobenzazolo[3,2-a]quinolinium Salts Induce Cell Death through a Mechanism Involving DNA Damage, Cell Cycle Changes, and Mitochondrial Permeabilization

This study reports the capacity of three nitro substituted benzazolo[3,2-a]quinolinium salts NBQs: NBQ 95 (NSC-763304), NBQ 38 (NSC 763305), and NBQ 97 (NSC-763306) as potential antitumor agents. NBQ's are unnatural alkaloids possessing a positive charge that could facilitate interaction with cell organelles. The anticancer activities of these compounds were evaluated through the National Cancer Institute (NCI) 60 cell line screening which represents diverse histologies. The screening was performed at 10 µM on all cell lines. Results from the NCI screening indicated cytotoxicity activity on six cell lines. In order to explore a possible mechanism of action, a detailed biological activity study of NBQ 95 and NBQ 38 was performed on A431 human epidermoid carcinoma cells to determine an apoptotic pathway involving, cell cycle changes, DNA fragmentation, mutations, mitochondrial membrane permeabilization and caspases activation. DNA fragmentation, cell cycle effects, mutagenesis, mitochondrial permeabilization and activation of caspases were determined by fluorimetry and differential imaging. Our data showed that A431 growth was inhibited with an average IC50 of 30 µM. In terms of the mechanism, these compounds interacted with DNA causing fragmentation and cell cycle arrest at sub G0/G1 stage. Mutagenesis was higher for NBQ 38 and moderate for NBQ 95 Mitochon-drial permeabilization was observed with NBQ 38 and slightly for NBQ 95. Both compounds caused activation of Caspases 3 and 7 suggesting an apoptotic cell death pathway through an intrinsic mechanism. This study reports evidence of the toxicity of these novel compounds with overlapping structural and mechanistic similarities to ellipticine, a known anti-tumor compound.

Mitochondrial permeability and toxicity of diethylhexyl and monoethylhexyl phthalates on TK6 human lymphoblasts cells

Phthalates are ubiquitous compounds used in the manufacturing industry. Some are known endocrine disruptors, acting as xenoestrogens, others induce reproductive toxicity and damage to DNA among other effects. Studies on apoptosis induction and mitochondrial damage capacity of phthalates on the immune system are limited. This study aims to determine cell viability inhibition and apoptosis induction of diethylhexyl phthalate (DEHP) and monoethylhexyl phthalate (MEHP) on the human TK6 lymphoblast cell line at concentrations found in the environment. Key hallmark events, such as mitochondrial membrane permeability, generation of reactive oxygen species (ROS) and activation of caspase 3 and 7 were measured. Concentrations that inhibit viability of 50% (IC50) of the cells were determined at 24, 48 and 72 h with doses ranging from 10 to 500 μM. Changes in mitochondrial membrane permeability, ROS generation and activation of caspases 3 and 7, were measured as part of the cell death mechanism. The IC50 at 24 h was approximately 250 μM for both phthalates; at 48 h were 234 and 196 μM for DEHP and MEHP, respectively and at 72 h IC50s were 100 and 80 μM for DEHP and MEHP, respectively. Overall the longer the time of exposure the lower the IC50's for both compounds. Both compounds affected mitochondrial membrane potential, promoted ROS generation and activated caspases 3 and 7. MEHP is more toxic, promotes higher level of ROS production and caspases activation. Our findings suggest that DEHP and MEHP have the capacity to induce apoptosis in cells of the immune system at concentrations found in the environment.

Abstract 1342: Effects of the plasticizer metabolite 2 ethyl-1-hexanol on human lymphoblast cells

The study main objective was to determine the toxicity of 2-ethyl-1-hexanol (EH) and to compare them to its precursor di-ethylhexyl phthalate (DEHP) on the TK6 human lymphoblast cell line. EH is an organic alcohol produced in cells as result of the biotransformation of DEHP. Release of EH from lung cancer cells was also reported recently. Environmental human exposure to the parent DEHP can result through interaction with personal care products, paint lacquer, inks, rubber, dry cleaning and plasticizers such as PVC. Analyzed effects in this study included doses that inhibit cell growth (IC50), damage to the mitochondrial membrane, generation of Reactive Oxygen Species (ROS), and activation of caspase 3 and 7. TK6 cells were cultured on 12.5cm2 flasks with modified RPMI 1640 culture media with 10% FBS, and incubated at 37°C with 5% CO2. IC50 was determined by trypan blue exclusion and mitochondrial membrane permeability applying the Mito PT JC-1 assay from Immunochemistry. For ROS determination the fluorescent dye 2,7-dichlorofluorescein diacetate (DCFH-DA) was applied. For caspases 3 and 7 analysis the Magic RedTM assay from Immunochemistry was applied. Results indicated that IC50s of DEHP and EH on TK6 cells were 234 μM and 75nM respectively. Cells where then exposed to the identified IC50 for 48 hours to measure effects on mitochondria and ROS generation. ROS results indicated that EH generated an average of 96.31 Fluorescence Standard Units (FSU), the negative control Dimethyl Sulphoxide (DMSO) generated 58.22 FSU, the compound used as positive control cis-Di ammine platinum (II) dichloride (Cisplatin) generated 1309.67 FSU and for DEHP the ROS analysis resulted on 793.27 FSU. The level of ROS generated between the parent and this metabolite are not consistent with the degree of toxicity observed. Determination and comparison of the mitochondrial membrane permeabilization as well as Caspases 3 and 7-activation assays of EH are still developing. The preliminary results, however indicates a wide difference in citotoxicity between the parent compound and its metabolite clearly supporting the need for prevention strategies reducing exposure to these controversial plasticizer and therefore potential health effects.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1342. doi:10.1158/1538-7445.AM2011-1342