MEASUREMENT OF PERSISTENT ORGANIC POLLUTANTS, PERFLUORINATED COMPOUNDS, AND TOXIC METALS IN THE BLOOD OF HUMBOLDT PENGUINS (SPHENISCUS HUMBOLDTI) AT PUNTA SAN JUAN, PERU USING DRIED BLOOD SPOTS.

The Humboldt penguin (Spheniscus humboldti) population at the Punta San Juan Marine Protected Area in Peru is considered critical to the long-term sustainability of this endangered species in Peru. Exposure of the rookery to environmental toxicants is a mounting concern because of regional growth of industries and human populations. Whole blood samples were collected from 30 free-ranging penguins in 2011 as part of a broader population health monitoring program. Dried blood spots (DBS) containing 50 µl of blood were prepared and analyzed to assess exposure to five groups of environmental contaminants. Concentrations of elements arsenic, cadmium, iron, lead, mercury, selenium, and thallium were analyzed using inductively coupled plasma mass spectrometry. Persistent organic pollutant concentrations were measured using gas chromatography-tandem mass spectrometry to analyze organochlorine pesticides (OCP; p,p'-DDT, p,p'-DDE, ß-hexachlorocyclohexane, t-nonachlor, and oxychlordane), polychlorinated biphenyls (congeners 138 and 153), and polybrominated flame retardants (polybrominated biphenyl-153 and polybrominated diphenyl ether congeners 47 and 99). Per- and polyfluoroalkyl substances, including perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid were measured using liquid chromatography-tandem mass spectrometry. Results revealed low levels of exposure to these selected contaminants, at levels not considered to be of concern for wildlife health. DBS methodology was considered effective in a field-based setting for quantification of whole blood concentrations of environmental contaminants in penguins.

A comprehensive review of treatments for hydrogen sulfide poisoning: past, present, and future.

Hydrogen sulfide (H2S) poisoning remains a significant source of occupational fatalities and is the second most common cause of toxic gas-induced deaths. It is a rapidly metabolized systemic toxicant targeting the mitochondria, among other organelles. Intoxication is mostly acute, but chronic or in-between exposure scenarios also occur. Some genetic defects in H2S metabolism lead to lethal chronic H2S poisoning. In acute exposures, the neural, respiratory, and cardiovascular systems are the primary target organs resulting in respiratory distress, convulsions, hypotension, and cardiac irregularities. Some survivors of acute poisoning develop long-term sequelae, particularly in the central nervous system. Currently, treatment for H2S poisoning is primarily supportive care as there are no FDA-approved drugs. Besides hyperbaric oxygen treatment, drugs in current use for the management of H2S poisoning are controversial. Novel potential drugs are under pre-clinical research development, most of which target binding the H2S. However, there is an acute need to discover new drugs to prevent and treat H2S poisoning, including reducing mortality and morbidity, preventing sequalae from acute exposures, and for treating cumulative pathology from chronic exposures. In this paper, we perform a comprehensive review of H2S poisoning including perspectives on past, present, and future.

Pre-exposure to hydrogen sulfide modulates the innate inflammatory response to organic dust.

Animal production units produce and store many contaminants on-site, including organic dust (OD) and hydrogen sulfide (H2S). Workers in these settings report various respiratory disease symptoms. Both OD and H2S have shown to induce lung inflammation. However, impact of co-exposure to both H2S and OD has not been investigated. Therefore, we tested a hypothesis that pre-exposure to H2S modulates the innate inflammatory response of the lungs to organic dust. In a mouse model of H2S and organic dust extract (ODE) exposure, we assessed lung inflammation quantitatively. We exposed human airway epithelial and monocytic cells to medium or H2S alone or H2S followed by ODE and measured cell viability, oxidative stress, and other markers of inflammation. Exposure to 10 ppm H2S followed by ODE increased the lavage fluid leukocytes. However, exposure to 10 ppm H2S alone resulted in changes in tight junction proteins, an increase in mRNA levels of tlr2 and tlr4 as well as ncf1, ncf4, hif1α, and nrf2. H2S alone or H2S and ODE exposure decreased cell viability and increased reactive nitrogen species production. ODE exposure increased the transcripts of tlr2 and tlr4 in both in vitro and in vivo models, whereas increased nfkbp65 transcripts following exposure to ODE and H2S was seen only in in vitro model. H2S alone and H2S followed by ODE exposure increased the levels of IL-1ß. We conclude that pre-exposure to H2S modulates lung innate inflammatory response to ODE.

Behavioral and Neuronal Effects of Inhaled Bromine Gas: Oxidative Brain Stem Damage.

The risk of accidental bromine (Br2) exposure to the public has increased due to its enhanced industrial use. Inhaled Br2 damages the lungs and the heart; however, adverse effects on the brain are unknown. In this study, we examined the neurological effects of inhaled Br2 in Sprague Dawley rats. Rats were exposed to Br2 (600 ppm for 45 min) and transferred to room air and cage behavior, and levels of glial fibrillary acidic protein (GFAP) in plasma were examined at various time intervals. Bromine exposure resulted in abnormal cage behavior such as head hitting, biting and aggression, hypervigilance, and hyperactivity. An increase in plasma GFAP and brain 4-hydroxynonenal (4-HNE) content also was observed in the exposed animals. Acute and delayed sympathetic nervous system activation was also evaluated by assessing the expression of catecholamine biosynthesizing enzymes, tryptophan hydroxylase (TrpH1 and TrpH2), and tyrosine hydroxylase (TyrH), along with an assessment of catecholamines and their metabolites. TyrH was found to be increased in a time-dependent manner. TrpH1 and TrpH2 were significantly decreased upon Br2 exposure in the brainstem. The neurotransmitter content evaluation indicated an increase in 5-HT and dopamine at early timepoints after exposure; however, other metabolites were not significantly altered. Taken together, our results predict brain damage and autonomic dysfunction upon Br2 exposure.

Broad spectrum proteomics analysis of the inferior colliculus following acute hydrogen sulfide exposure.

Acute exposure to high concentrations of H2S causes severe brain injury and long-term neurological disorders, but the mechanisms involved are not known. To better understand the cellular and molecular mechanisms involved in acute H2S-induced neurodegeneration we used a broad-spectrum proteomic analysis approach to identify key molecules and molecular pathways involved in the pathogenesis of acute H2S-induced neurotoxicity and neurodegeneration. Mice were subjected to acute inhalation exposure of up to750 ppm of H2S. H2S induced behavioral deficits and severe lesions including hemorrhage in the inferior colliculus (IC). The IC was microdissected for proteomic analysis. Tandem mass tags (TMT) liquid chromatography mass spectrometry (LC-MS/MS)-based quantitative proteomics was applied for protein identification and quantitation. LC-MS/MS identified 598, 562, and 546 altered proteomic changes at 2 h, and on days 2 and 4 post-H2S exposure, respectively. Of these, 77 proteomic changes were statistically significant at any of the 3 time points. Mass spectrometry data were subjected to Perseus 1.5.5.3 statistical analysis, and gene ontology heat map clustering. Expressions of several key molecules were verified to confirm H2S-dependent proteomics changes. Webgestalt pathway overrepresentation enrichment analysis with Panther engine revealed H2S exposure disrupted several biological processes including metabotropic glutamate receptor group 1 and inflammation mediated by chemokine and cytokine signaling pathways among others. Further analysis showed that energy metabolism, integrity of blood-brain barrier, hypoxic, and oxidative stress signaling pathways were also implicated. Collectively, this broad-spectrum proteomics data has provided important clues to follow up in future studies to further elucidate mechanisms of H2S-induced neurotoxicity.

Extensive evaluation of a new LC-MS-MS method to quantify monofluoroacetate toxin in the kidney.

Monofluoroacetate is a highly lethal toxin that causes death by inhibiting cellular adenosine triphosphate (ATP) production. The heart and brain are the primary target organs. Acute death is attributed to cardiac fibrillation and/or convulsions. Although it occurs naturally in some plants, a major source of animal intoxication is access to sodium monofluoroacetate (NaMFA) pesticide, which continues to be a concern in the USA and around the world despite restricted use in some countries including the USA. There are also concerns about misuse of this pesticide for malicious poisoning. Currently, a tissue-based diagnostic method for NaMFA intoxication in animals is lacking. There is a critical need by the veterinary diagnostic community for a simple, sensitive and reliable tissue-based diagnostic test to confirm NaMFA poisoning in animals. We have developed and extensively evaluated a sensitive novel liquid chromatography combined with tandem mass spectrometry method suitable for this purpose. The limits of detection and limits of quantitation are 1.7 and 5.0 ng/g, respectively. The accuracy and precision met or exceeded expectations. The method performance was verified using the incurred kidney obtained from animal diagnostic cases. This novel kidney-based method is now available for clinical use and can help with diagnostic purposes, including detecting potential issues related to animal foods.

A survey to document toxic hazards in the zone surrounding volcanoes national park, a habitat for mountain gorillas, an endangered wildlife species in Rwanda.

Introduction: In recent years, Volcanoes National Park has seen a rise in its wildlife population, primarily due to the diligent efforts of the Rwandan government in safeguarding endangered species, notably the mountain gorillas (Gorilla beringei spp. beringei). This population growth has led to a pressing need for more expansive habitats, ensuring these creatures have ample space, sustenance, and shelter for their wellbeing. Consequently, there are planned park expansion activities on the horizon. However, before initiating this expansion, a critical prelude involves identifying potential threats, particularly toxic substances stemming from agricultural activities in the surrounding environment of Volcanoes National Park. Methods: To address this concern, a comprehensive study was conducted, aimed at pinpointing potential toxic hazards and assessing the awareness of the local population regarding the harm these hazards pose to wildlife species. Data was collected from individuals with no prior knowledge of the study using a pre-tested questionnaire. The questionnaire was divided into three sections: socio-demographic issues, potential toxic hazards assessment, and a section to determine awareness and risk of potential toxic hazards to humans, animals, and the environment. Respondents were selected based on specific criteria, which included being 18 years or older and residing within the National Volcano Park (NVP) area. Results: The study's findings revealed four main categories of potential toxic hazards, which include household chemicals, pharmaceutical products, agricultural pesticides, and poisonous plants. These hazards could jeopardize the health and survival of wildlife species if they consume or come into contact with them. Furthermore, the study exposed an inadequacy in the knowledge and skills of the local community in preventing these toxic hazards, which can result in death of wildlife species and ecosystem contamination and degradation. Conclusion: Study results also underscored the significance of education and training in enhancing the awareness of local communities concerning these toxic threats. Therefore, it is imperative to implement immediate measures to mitigate the adverse effects of these toxic hazards on wildlife species, especially in light of the planned park expansion.

Disrupted brain mitochondrial morphology after in vivo hydrogen sulfide exposure.

Changes in mitochondrial dynamics are often associated with dietary patterns, medical treatments, xenobiotics, and diseases. Toxic exposures to hydrogen sulfide (H2S) harm mitochondria by inhibiting Complex IV and via other mechanisms. However, changes in mitochondrial dynamics, including morphology following acute exposure to H2S, are not yet fully understood. This study followed mitochondrial morphology changes over time after a single acute LCt50 dose of H2S by examining electron microscopy thalami images of surviving mice. Our findings revealed that within the initial 48 h after H2S exposure, mitochondrial morphology was impaired by H2S, supported by the disruption and scarcity of the cristae, which are required to enhance the surface area for ATP production. At the 72-h mark point, a spectrum of morphological cellular changes was observed, and the disordered mitochondrial network, accompanied by the probable disruption of mitophagy, was tied to changes in mitochondrial shape. In summary, this study sheds light on how acute exposure to high levels of H2S triggers alterations in mitochondrial shape and structure as early as 24 h that become more evident at 72 h post-exposure. These findings underscore the impact of H2S on mitochondrial function and overall cellular health.

Investigations into hydrogen sulfide-induced suppression of neuronal activity in vivo and calcium dysregulation in vitro.

Acute exposure to high concentrations of hydrogen sulfide (H2S) leads to sudden death and, if survived, lingering neurological disorders. Clinical signs include seizures, loss of consciousness, and dyspnea. The proximate mechanisms underlying H2S-induced acute toxicity and death have not been clearly elucidated. We investigated electrocerebral, cardiac and respiratory activity during H2S exposure using electroencephalogram (EEG), electrocardiogram (EKG) and plethysmography. H2S suppressed electrocerebral activity and disrupted breathing. Cardiac activity was comparatively less affected. To test whether Ca2+ dysregulation contributes to H2S-induced EEG suppression, we developed an in vitro real-time rapid throughput assay measuring patterns of spontaneous synchronized Ca2+ oscillations in cultured primary cortical neuronal networks loaded with the indicator Fluo-4 using the fluorescent imaging plate reader (FLIPR-Tetra®). Sulfide >5 ppm dysregulated synchronous calcium oscillation (SCO) patterns in a dose-dependent manner. Inhibitors of NMDA and AMPA receptors magnified H2S-induced SCO suppression. Inhibitors of L-type voltage gated Ca2+ channels and transient receptor potential channels prevented H2S-induced SCO suppression. Inhibitors of T-type voltage gated Ca2+ channels, ryanodine receptors, and sodium channels had no measurable influence on H2S-induced SCO suppression. Exposures to > 5 ppm sulfide also suppressed neuronal electrical activity in primary cortical neurons measured by multi-electrode array (MEA), an effect alleviated by pretreatment with the nonselective transient receptor potential channel inhibitor, 2-APB. 2-APB also reduced primary cortical neuronal cell death from sulfide exposure. These results improve our understanding of the role of different Ca2+ channels in acute H2S-induced neurotoxicity and identify transient receptor potential channel modulators as novel structures with potential therapeutic benefits.

Acute hydrogen sulfide-induced neurochemical and morphological changes in the brainstem.

Hydrogen sulfide (H2S) is a toxin affecting the cardiovascular, respiratory, and central nervous systems. Acute H2S exposure is associated with a high rate of mortality and morbidity. The precise pathophysiology of H2S-induced death is a controversial topic; however, inhibition of the respiratory center in the brainstem is commonly cited as a cause of death. There is a knowledge gap on toxicity and toxic mechanisms of acute H2S poisoning on the brainstem, a brain region responsible for regulating many reflective and vital functions. Serotonin (5-HT), dopamine (DA), and γ-aminobutyric acid (GABA) play a role in maintaining a normal stable respiratory rhythmicity. We hypothesized that the inhibitory respiratory effects of H2S poisoning are mediated by 5-HT in the respiratory center of the brainstem. Male C57BL/6 mice were exposed once to an LCt50 concentration of H2S (1000 ppm). Batches of surviving mice were euthanized at 5 min, 2 h, 12 h, 24 h, 72 h, and on day 7 post-exposure. Pulmonary function, vigilance state, and mortality were monitored during exposure. The brainstem was analyzed for DA, 3,4-dehydroxyphenyl acetic acid (DOPAC), 5-HT, 5-hydroxyindoleatic acid (5-HIAA), norepinephrine (NE), GABA, glutamate, and glycine using HPLC. Enzymatic activities of monoamine oxidases (MAO) were also measured in the brainstem using commercial kits. Neurodegeneration was assessed using immunohistochemistry and magnetic resonance imaging. Results showed that DA and DOPAC were significantly increased at 5 min post H2S exposure. However, by 2 h DA returned to normal. Activities of MAO were significantly increased at 5 min and 2 h post-exposure. In contrast, NE was significantly decreased at 5 min and 2 h post-exposure. Glutamate was overly sensitive to H2S-induced toxicity manifesting a time-dependent concentration reduction throughout the 7 day duration of the study. Remarkably, there were no changes in 5-HT, 5-HIAA, glycine, or GABA concentrations. Cytochrome c oxidase activity was inhibited but recovered by 24 h. Neurodegeneration was observed starting at 72 h post H2S exposure in select brainstem regions. We conclude that acute H2S exposure causes differential effects on brainstem neurotransmitters. H2S also induces neurodegeneration and biochemical changes in the brainstem. Additional work is needed to fully understand the implications of both the short- and long-term effects of acute H2S poisoning on vital functions regulated by the brainstem.

Extensive Evaluation of a Method for Quantitative Measurement of Aflatoxins B1 and M1 in Animal Urine Using High-Performance Liquid Chromatography with Fluorescence Detection.

BACKGROUND: Aflatoxins (AFs) are common feed contaminants and are one of the common causes of toxin-related pet food poisoning and recalls. OBJECTIVE: Currently, there are no validated methods for the detection and quantitation of AFs in biological matrices to diagnose AF exposure in live animals. Following a successful intra-laboratory method development to quantify AFB1 and AFM1 in animal urine by HPLC with fluorescence detection (HPLC-FLD), the present study was conducted to extensively evaluate the method performance in an unbiased manner using blinded samples. METHODS: The evaluation included two stages. First, the performance was verified in the method-originating laboratory in a single-laboratory blinded method test (BMT-S) trial followed by a multi-laboratory blinded method test (BMT-M) trial. RESULTS: In both trials, accuracy, repeatability, and reproducibility were satisfactory confirming the relatively good ruggedness and robustness of the method and ensuring that it will perform as expected if used by other laboratories in the future. CONCLUSIONS: We extensively evaluated the performance of a quantitative method to detect AFB1 and AFM1 in animal urine by HPLC-FLD by two different laboratories in two separate BMT-S and BMT-M trials. Both BMT results demonstrated the satisfactory accuracy and precision of the method. It is now available to be adopted by other diagnostic laboratories for purposes of diagnosing AF intoxication in animals. HIGHLIGHTS: A simple urine-based diagnostic test method using HPLC-FLD that originated in a single laboratory now has passed a multi-laboratory evaluation and is now available to be shared with other diagnostic laboratories for purposes of diagnosing AF intoxication in animals so better treatment can be rendered.

Examination of Eurasian griffon vultures (Gyps fulvus fulvus) in Israel for exposure to environmental toxicants using dried blood spots.

The griffon vulture (Gyps fulvus) is one of seven species of Old World Gyps vultures found over a wide range from the Iberian peninsula in the west through the Balkans, Turkey, and the Middle East to India in the east. The population of the griffon vultures in Israel has suffered a dramatic decrease, and in recent years productivity has been severely reduced. In this study, whole-blood samples taken from 25 apparently healthy griffon vultures at various stages of maturity were examined to investigate whether the vultures are being excessively exposed to environmental contaminants that might deleteriously affect their reproduction. Five groups of environmental contaminants, comprising toxic elements, organochlorine pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers, and perfluorinated compounds, were monitored in dried blood spots. Results of the analyses showed low levels of exposure of griffon vultures to environmental contaminants compared with the sparse data available on griffon vultures and other diurnal raptors in other countries.

A database of avian blood spot examinations for exposure of wild birds to environmental toxicants: the DABSE biomonitoring project.

DABSE, a database for avian blood spot examination for exposure to toxicants, is a new biomonitoring project in wild birds that has the goal of providing reference values of harmful agents, as measured in whole blood stored as dried blood spots. Once these "normal" values have been established, the diagnosis of environmental contaminant-mediated ill-health (such as manifestations of sickness, increased mortality, a reduction in population, poor breeding success, abnormal behavior) in an individual bird or in a population could be facilitated by comparing exposure values in the investigation to reference values of the same species in the database. One might then identify the cause and pave the way for a mitigating response. The toxicant component of DABSE is being examined at the low ng ml(-1) level in 200 µl of whole blood. As these analyses are invariably very costly, an effort has been made to lower these costs and so enable more testing by quantitating representative compounds as markers for the whole group. These markers are invariably found in birds' blood at the highest concentration of all the constituents in that group. The toxicant groups comprise:- (a) elements-arsenic, cadmium, lead, mercury and selenium; (b) organochlorine pesticides, markers being p,p'-DDT, p,p'-DDE, ß-HCH, HCB and oxychlordane; (c) polychlorinated biphenyls (PCBs), the marker being congener 153; (d) polybrominated diphenyl esters (PBDEs), the marker being congener 47; (e) perfluorinated compounds (PFCs), the markers being perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). DABSE will be expanded to determine exposure to infectious diseases and perhaps acute toxicoses.

Ambient hydrogen sulfide exposure increases the severity of influenza A virus infection in swine.

Hydrogen sulfide (H2S) is common in concentrated pig feed operations from the decomposition of manure. Ambient H2S is a respiratory tract irritant and an environmental stressor for caretakers and pigs. Influenza A virus (IAV), a zoonotic pathogen, has caused prior pandemics. The effects of H2S or IAV alone on the respiratory system have been investigated, but their interaction has not. We hypothesized that exposure to environmentally-relevant H2S concentrations increases the pathogenicity of IAV infection in swine. Thirty-five, three-week old pigs of mixed sex were exposed to breathing air or H2S via inhalation 6 hours daily for 12 days. After 7 days, pigs were inoculated with H3N2 IAV (or a placebo). Results showed that ambient H2S increased the severity of respiratory distress and lung pathology. H2S also suppressed IL-IL-1ß, IL-6 and IL-8 cytokine response in BALF and increased viral loads and nasal shedding.

Soft-tissue mineralization of bullfrog larvae (Rana catesbeiana) at a wastewater treatment facility.

Bullfrog tadpoles (Rana catesbeiana) from a wastewater treatment facility were identified with severe lesions consisting of large, up to 1-cm in diameter, mineralized nodules protruding from the tail or gular region. Sectioning of formalin-fixed specimens revealed more extensive mineralization involving the vertebrae or muscles of the head and tail. Nodules examined microscopically were not associated with parasitic or infectious agents. Large nodules consisted of mineralized aggregates surrounded by a margin of granulomatous inflammation. Individual connective-tissue fibers and muscle cells were mineralized at some foci. The nodules consisted entirely of calcium phosphate, and the lesions appeared to be novel. Total serum-calcium concentrations of tadpoles and calcium concentrations in water samples did not differ significantly with increasing distance from the discharge site. Affected tadpoles had elevated cholecalciferol (25-OH-vitamin D3) levels. Effluent from this wastewater treatment facility is divided into 3 streams, each passing through a separate series of wetlands allowing for replicated evaluation of tadpoles with increasing distance from the proximate inputs of treated wastewater. The prevalence of lesions was correlated with proximity of cells to the initial wastewater discharge site, and 28.5% of bullfrog larvae in the first cells had lesions. None were affected in the fifth cells. Southern leopard frog larvae (Rana sphenocephala), the only other species affected, had a much lower prevalence of lesions (<1%) than bullfrog tadpoles and were only affected in the first cells. To date, the primary cause of elevated cholecalciferol is undetermined, but it appears to be remediated by passage of water through the wetlands.

Residues in Brandt's voles (Microtus brandti) exposed to bromadiolone-impregnated baits in Mongolia.

In 2002, hundreds of non-target wildlife deaths occurred in Mongolia following aerial applications of bromadiolone, an anticoagulant rodenticide, to control eruptive Brandt's vole (Microtus brandti) populations. To clarify whether secondary poisoning could have contributed to these deaths, a field study was undertaken in Mongolia to measure bromadiolone residues in voles following exposure to two concentrations (50 and 500 mg/kg) of bromadiolone-treated wheat. The two treatments produced different total burdens (2.65 microg+/-0.53SE and 13.70 microg+/-3.82SE, respectively) and liver burdens (1.74 microg+/-0.33SE and 8.81 microg+/-2.33SE, respectively) of bromadiolone in voles (both p<0.05). Total burdens of bromadiolone in voles found dead above ground were higher than those of live-trapped voles (32.35 microg+/-17.98SE versus 5.18 microg+/-1.40SE, respectively; p<0.05). These results are valuable for future assessments of secondary poisoning risk to scavengers and predators from large-scale bromadiolone poisoning operations of the type undertaken in Mongolia.

Lessons Learned from ToxMSDT: A Pilot Innovative Toxicology Research Education Pipeline Program Targeting Underrepresented Undergraduate Students to the Field of Toxicology.

Toxicology, as a profession, lacks diversity. Undergraduate students, and especially underrepresented students, are not commonly introduced to toxicology at US colleges and universities. The Toxicology Mentoring and Skills Development Training Program (ToxMSDT) seeks to acquaint underrepresented undergraduates enrolled in STEM fields with toxicology fundamentals and skills to aid their entry into graduate programs and, ultimately, careers in toxicology. ToxMSDT is a collaboration among three universities. It is a year-long holistic training and mentoring program comprised of web resources accessible 24/7 and extensive one-to-one mentor-mentee interactions throughout the year. Evaluation of the two-year pilot program shows that students expressed a significant increase in knowledge about toxicology careers, networking with people involved in the field of toxicology, feelings of being part of the toxicology community, and seeing themselves as someone who will study toxicology, compared with their feelings prior to their participation in the ToxMSDT program. Thirty students have completed the ToxMSDT program and all 10 (100%) of those who have graduated have joined graduate school in toxicology or toxicology-related STEM fields. Of the 20 (66.6%) program alumni still enrolled as undergraduates, five (25%) are in the process of applying to graduate programs and medical schools as of August 2019.

Transcriptomic profile analysis of brain inferior colliculus following acute hydrogen sulfide exposure.

Hydrogen sulfide (H2S) is a gaseous molecule found naturally in the environment, and as an industrial byproduct, and is known to cause acute death and induces long-term neurological disorders following acute high dose exposures. Currently, there is no drug approved for treatment of acute H2S-induced neurotoxicity and/or neurological sequelae. Lack of a deep understanding of pathogenesis of H2S-induced neurotoxicity has delayed the development of appropriate therapeutic drugs that target H2S-induced neuropathology. RNA sequencing analysis was performed to elucidate the cellular and molecular mechanisms of H2S-induced neurodegeneration, and to identify key molecular elements and pathways that contribute to H2S-induced neurotoxicity. C57BL/6J mice were exposed by whole body inhalation to 700 ppm of H2S for either one day, two consecutive days or 4 consecutive days. Magnetic resonance imaging (MRI) scan analyses showed H2S exposure induced lesions in the inferior colliculus (IC) and thalamus (TH). This mechanistic study focused on the IC. RNA Sequencing analysis revealed that mice exposed once, twice, or 4 times had 283, 193 and 296 differentially expressed genes (DEG), respectively (q-value < 0.05, fold-change> 1.5). Hydrogen sulfide exposure modulated multiple biological pathways including unfolded protein response, neurotransmitters, oxidative stress, hypoxia, calcium signaling, and inflammatory response in the IC. Hydrogen sulfide exposure activated PI3K/Akt and MAPK signaling pathways. Pro-inflammatory cytokines were shown to be potential initiators of the modulated signaling pathways following H2S exposure. Furthermore, microglia were shown to release IL-18 and astrocytes released both IL-1ß and IL-18 in response to H2S. This transcriptomic analysis data revealed complex signaling pathways involved in H2S-induced neurotoxicity and may provide important associated mechanistic insights.

High-performance liquid chromatography and Enzyme-Linked Immunosorbent Assay techniques for detection and quantification of aflatoxin B1 in feed samples: a comparative study.

OBJECTIVE: Comparison was done between high-performance liquid chromatography (HPLC) and a competitive enzyme-linked immunosorbent assay (ELISA) for detection and quantification of aflatoxin B1 (AFB1) in feed samples. The two procedures were standardized and validated before the actual experiment. Five concentrations (0, 5, 10, 20 and 30 ppb) of feed samples were used for both methods. For the HPLC technique, the samples were extracted in acetonitrile/water (90/10) solution, cleaned-up using solid phase extraction (SPE) column, and derivatized by water/trifluoroacetic acid/glacial acetic acid (35/10/5) solution before instrument analysis. The samples were extracted in 70% methanol for the ELISA technique. RESULTS: The two tests showed very strong linearity with correlation coefficient value of > 0.99 using standard solutions. The mean recovery rate was 92.42% (with relative standard deviation (RSD) of 5.97) and 75.64% (RSD = 34.88) for HPLC and ELISA, respectively. There was no statistically significant difference in recovery rate between the two methods. There was a positive correlation (r = 0.84) between them which indicated that the two techniques can be used to detect and quantify aflatoxin B1 in feed samples. However, there were variations among replicates for the ELISA method, which shows that this method is more applicable for screening purposes.

Evaluation of a Diagnostic Method to Quantify Aflatoxins B1 and M1 in Animal Liver by High-Performance Liquid Chromatography with Fluorescence Detection.

Background: Aflatoxins (AFs) are secondary metabolites of fungi and are one of the causes of toxin-related pet food recalls. An intralaboratory method was previously developed to quantify aflatoxin B1 (AFB1) and aflatoxin M1 (AFM1) in animal liver by HPLC with fluorescence detection. Objective: The aim of this study was to extensively evaluate the method performance with a single-laboratory blinded method test (BMT-S) and a multilaboratory blinded method test (BMT-M). Methods: Blinded tissue samples were prepared by a third-party laboratory and sent out to participating laboratories for both BMT-S and BMT-M. Results: In both tests, participants analyzed blinded samples prepared by an independent laboratory. In the BMT-S, accuracy ranged between 111 and 154% for AFB1 and 113 and 159% for AFM1 within the quantitation range of 0.1-0.5 ng/g. The HorRat values for repeatability ranged between 0.1 and 0.3 for AFB1 and 0.3 and 0.6 for AFM1. In the BMT-M, the interlaboratory accuracy ranged between 77 and 81% for AFB1 and 83 and 85% for AFM1 within the quantitation range of 0.2-10 ng/g. The HorRat values for reproducibility ranged between 0.4 and 0.7 for AFB1 and 0.4 and 0.9 for AFM1. Both recovery and reproducibility were acceptable. Conclusions: BMT-M evaluation demonstrated that the method was suitable for quantitation of aflatoxins B1 and M1 in animal liver between laboratories. Highlights: The BMT-S and BMT-M results demonstrated that the method is rugged and reproducible among the participating laboratories.