Browsing by Author "Hrubec, Terry C."

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    Age and Sex Related Behavioral Changes in Mice Congenitally Infected with Toxoplasma gondii: Role of dopamine and other neurotransmitters in the genesis of behavioral changes due to congenital infection and attempted amelioration with interferon gamma
    Goodwin, David G. (Virginia Tech, 2011-07-12)
    Evidence suggests that the neurotropic parasite Toxoplasma gondii may play a role in the development of cognitive impairments. My hypothesis was that congenital exposure to T. gondii would lead to detectable age and sex related differences in behavior and neurotransmitter levels in mice. The neurotransmitter dopamine and commonly used anti-schizophrenic agents were evaluated against T. gondii in human fibroblast cells. Dopamine caused a significant increase in tachyzoite numbers at 250 nM but not 100 nM and the drugs valproic acid, fluphenazine, thioridazine and trifluoperazine inhibited T. gondii development. The effects T. gondii infection had on behavior were examined using a congenital mouse model. Previous work demonstrated maternal immune stimulation (MIS) with interferon gamma (INF-g) resulted in decreased fetal mortality from congenital T. gondii infections; therefore I examined the effects of INF- g treatment of mothers to determine if protection from the behavioral effects of T. gondii occurred in their offspring. No differences in concentrations of neurotransmitters in the brains of congenitally infected mice were observed. I found that mice infected with T. gondii developed adult onset behavior impairments with decreased rate of learning, increased activity and decreased memory, indicating cognitive impairment for male mice and not female mice. My findings support the evidence T. gondii is a factor in the development of cognitive impairments. My results for T. gondii exposed male mice are consistent with the convention that males have more cognitive impairments in the prodromal stage of schizophrenia. MIS with IFN-g had a minimal effect on behavior post sexual maturity but had a greater effect on pre sexual maturity female mice which exhibited difficulties with spatial memory, coordination and the ability to process stimuli. The results indicate the behavior alterations from IFN- g are transient. When MIS is given prior to congenital infection with T. gondii, we detected no behavior deficits in any group of mice, including male mice post sexual maturity. Based on the results of my study, I must reject the hypothesis that neurotransmitter levels are influenced by congenital toxoplasmosis and accept the hypothesis that congenital T. gondii infection caused cognitive impairments in male mice post sexual maturity.
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    Altered toxicological endpoints in humans from common quaternary ammonium compound disinfectant exposure
    Hrubec, Terry C.; Seguin, Ryan P.; Xu, L.; Cortopassi, G. A.; Datta, S.; Hanlon, Alexandra L.; Lozano, A. J.; McDonald, V. A.; Healy, C. A.; Anderson, T. C.; Musse, N. A.; Williams, R. T. (Elsevier, 2021-01-01)
    Humans are frequently exposed to Quaternary Ammonium Compounds (QACs). QACs are ubiquitously used in medical settings, restaurants, and homes as cleaners and disinfectants. Despite their prevalence, nothing is known about the health effects associated with chronic low-level exposure. Chronic QAC toxicity, only recently identified in mice, resulted in developmental, reproductive, and immune dysfunction. Cell based studies indicate increased inflammation, decreased mitochondrial function, and disruption of cholesterol synthesis. If these findings translate to human toxicity, multiple physiological processes could be affected. This study tested whether QAC concentrations could be detected in the blood of 43 human volunteers, and whether QAC concentrations influenced markers of inflammation, mitochondrial function, and cholesterol synthesis. QAC concentrations were detected in 80 % of study participants. Blood QACs were associated with increase in inflammatory cytokines, decreased mitochondrial function, and disruption of cholesterol homeostasis in a dose dependent manner. This is the first study to measure QACs in human blood, and also the first to demonstrate statistically significant relationships between blood QAC and meaningful health related biomarkers. Additionally, the results are timely in light of the increased QAC disinfectant exposure occurring due to the SARS-CoV-2 pandemic. Main Findings: This study found that 80 % of study participants contained QACs in their blood; and that markers of inflammation, mitochondrial function, and sterol homeostasis varied with blood QAC concentration.
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    Ambient and Dosed Exposure to Quaternary Ammonium Disinfectants Causes Neural Tube Defects in Rodents
    Hrubec, Terry C.; Melin, Vanessa E.; Shea, Caroline S.; Ferguson, Elizabeth E.; Garofola, Craig; Repine, Claire M.; Chapman, Tyler W.; Patel, Hiral R.; Razvi, Reza M.; Sugrue, Jesse E.; Potineni, Haritha; Magnin, Geraldine; Hunt, Patricia A. (2017-08-15)
    Background: Quaternary ammonium compounds are a large class of chemicals used for their antimicrobial and antistatic properties. Two common quaternary ammonium compounds, alkyldimethylbenzyl ammonium chloride (ADBAC) and didecyldimethyl ammonium chloride (DDAC), are combined in common cleaners and disinfectants. Introduction of a cleaner containing ADBAC+DDAC in the vivarium caused neural tube defects (NTDs) in mice and rats. Methods: To further evaluate this finding, male and female mice were dosed in the feed at 60 or 120 mg/kg/day, or by oral gavage at 7.5, 15, or 30 mg/kg ADBAC+DDAC. Mice also received ambient exposure to ADBAC+DDAC from the disinfectant used in the mouse room. Embryos were evaluated on gestational day 10 for NTDs, and fetuses were evaluated on gestational day 18 for gross and skeletal malformations. Results: We found increased NTDs with exposure to ADBAC+DDAC in both rats and mice. The NTDs persisted for two generations after cessation of exposure. Notably, male exposure alone was sufficient to cause NTDs. Equally significant, ambient exposure from disinfectant use in the vivarium, influenced the levels of NTDs to a greater extent than oral dosing. No gross or significant axial skeletal malformations were observed in late gestation fetuses. Placental abnormalities and late gestation fetal deaths were increased at 120 mg/kg/day, which might explain the lack of malformations observed in late gestation fetuses. Conclusion: These results demonstrate that ADBAC+DDAC in combination are teratogenic to rodents. Given the increased use of these disinfectants, further evaluation of their safety in humans and their contribution to health and disease is essential. (C) 2017 The Authors. Birth Defects Research Published by Wiley Periodicals, Inc.
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    Congenital infection of mice with toxoplasma gondii induces minimal change in behavior and no change in neurotransmitter concentrations
    Goodwin, David G.; Hrubec, Terry C.; Klein, Bradley G.; Strobl, Jeannine S.; Werre, Stephen R.; Han, Qian; Zajac, Anne M.; Lindsay, David S. (American Society of Parasitology, 2012-08-01)
    We examined the effect of maternal Toxoplasma gondii infection on behavior and the neurotransmitter concentrations of congenitally infected CD-I mice at 4 and 8 wk of age when latent tissue cysts would be present in their brains. Because of sex-associated behavioral changes that develop during aging, infected female mice were compared with control females and infected male mice were compared with control males. Only the short memory behavior (distance between goal box and first hole investigated) of male mice congenitally infected with T. gondii was significantly different (P < 0.05) from that of uninfected control males at both 4 and 8 wk by using the Barnes maze test. The other parameters examined in the latter test, i.e., functional observational battery tests, virtual cliff, visual placement, and activity tests, were not significantly different (P > 0.05) at 4 and 8 wk. Concentrations of neurotransmitters and their metabolites (dopamine; 3,4-dihydroxyphenylacetic acid; homovanillic acid; norepinephrine; epinephrine; 3-methoxy-4-hydroxyphenylglycol; serotonin; and 5-hydroxyindoleacetic acid) in the frontal cortex and striatum were not different (P > 0.05) between infected and control mice at 8 wk of age. The exact mechanism for the observed effect on short-term memory in male mice is not known, and further investigation may help elucidate the molecular mechanisms associated with the proposed link between behavioral changes and T gondil infection in animals. We were not able, however, to confirm the widely held belief that changes in neurotransmitters result from chronic T. gondii infection of the brain.
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    Effects of Quaternary Ammonium Disinfectants on Mouse Reproductive Function
    Melin, Vanessa Estella (Virginia Tech, 2015-07-25)
    Quaternary ammonium compounds (QACs) are antimicrobial disinfectants commonly used in commercial and household settings. While these compounds have been used for decades, reproductive toxicity has not been thoroughly evaluated. Extensive use of QACs results in ubiquitous human exposure to potentially toxic compounds. Reproductive toxicity of two common QACs, alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC), was investigated to determine gender-specific toxicity with an emphasis on male reproductive function. Breeding pairs of mice exposed for six months to ADBAC+DDAC exhibited decreases in fertility and fecundity, with fewer pregnancies and decreased numbers of pups over a six month period. Females proceeded through significantly fewer estrus cycles, and both ovulation and implantation rates were reduced. Males exhibited declines in both sperm concentration and motility. Male reproductive toxicity was further assessed in a series of in-vitro and in-vivo experiments. ADBAC+DDAC were cytotoxic to testicular Sertoli cells in culture at concentrations greater than or equal to 0.0005%. Changes in blood-testis-barrier integrity (BTB) were observed at 0.01% ADBAC+DDAC using a two-compartment culture system that measures transepithelial electrical resistance (TER). Sertoli cell cytotoxicity correlated with decreased TER at ADBAC+DDAC concentrations above 0.001%. In-vitro fertilization capacity of epididymal sperm was reduced in males given a 10-day rest period following ADBAC+DDAC exposure. Multigenerational changes in sperm parameters and in mRNA expression of enzymes involved with epigenetic modifications were evaluated across three generations. Sperm concentration and motility were reduced in F0 males exposed directly to ADBAC+DDAC. In F1 males, sperm concentration was increased and motility decreased, while there was no change in the F2 progeny. Genes involved in epigenetic modifications were altered in the exposed F0, with upregulation of two histone acetyltransferases (Hat1 and Kat2b) and downregulation of one lysine-specific demethylase (Kdm6b). F1 and F2 generations were not different from controls except for downregulation of the methyltransferase Dnmt1 in F1 progeny. The reproductive toxicity of ADBAC+DDAC identified in these studies, particularly to the male, compels further investigation into the potential effects that these compounds may have on human reproduction.
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    Evaluating Immunotoxicity of Quaternary Ammonium Compounds
    McDonald, Valerie Alexandra (Virginia Tech, 2017-10-19)
    Alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC) are common quaternary ammonium compounds used as disinfectants in households, medical, and restaurant settings. They cause occupational skin and respiratory hazards in humans, and developmental and reproductive toxicity in mice. They also cause increased secretions of proinflammatory cytokines in cell lines and vaginal inflammation in porcine models; but have not been evaluated for developmental immunotoxicity. We assessed immunotoxicity in-vitro with J774A.1 murine macrophage cell line by analyzing cytokine production and phagocytosis; and evaluated developmental immunotoxicity in CD-1 mice by analyzing antibody production. Additionally, because of the associations between gut microbiome dysbiosis and immune disease, we monitored changes in the microbiome as a result of ADBAC+DDAC exposure. Production of cytokines TNF-alpha and IL-6 increased at low ADBAC+DDAC concentrations, and IL-10 decreased in the murine macrophages with ADBAC+DDAC exposure. The phagocytic function of macrophages was also severely decreased. ADBAC+DDAC altered the mouse microbiome by decreasing the relative abundance of Bacteroides and increases in Clostridia in F0 and F1 generations. IgG primary and secondary responses were altered in F1 male mice; and IgA and IgM production were decreased in secondary response in F2 male mice. Since ADBAC+DDAC show signs of immunotoxicity in mice, further studies are needed to reassess risk for human exposure as ADBAC+DDAC may be contributing to immune disease.
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    Neural tube defects in rodents caused by a tap water contaminant
    Melin, Vanessa Estella (Virginia Tech, 2011-09-28)
    In May of 2006, the Hrubec group suddenly began to observe neural tube defects (NTDs) in embryos of untreated control mice. Unintentional exposure to a teratogenic agent in tap water was identified as the cause. We aimed to identify the contaminant, but first we demonstrated that the NTDs were pathological being present on both gestational day 9 and 10. We also found that a second species, rats, developed NTDs when exposed to tap waters. Disinfection by-products (DBPs) arise when natural organic matter in municipal water sources reacts with disinfectants used in the water treatment process. Purge and trap gas chromatography-mass spectrometry (PT GC-MS) and animal exposure studies were used to determine if the teratogenic contaminant was a DBP. Since the distribution pattern of DBPs did not match the distribution pattern of NTDs, we concluded that a DBP was not likely to be responsible for the observed malformations. Pharmaceuticals and personal care products have emerged as ubiquitous contaminants of ground and surface waters, and have been detected in drinking water. In order to analyze for these compounds, we submitted different water samples to a commercial water analysis lab (AXYS Analytical Services, Sidney, BC, Canada). Several pharmaceuticals were identified in a number of samples, including a known teratogenic drug used to treat mood disorders and seizures: carbamazepine. Further analysis for carbamazepine was conducted in-house. Carbamazepine was found in several ground, surface, and tap waters, at various concentrations. To establish whether or not carbamazepine was responsible for NTDs in our mice, we conducted 2 dosing studies. Carbamazepine was provided to mice at concentrations detected in tap water, as well as approximately 2 x and 1000 x that concentration. Both studies found no significant differences in NTD rates among the dose groups. As no dose effect was observed, we concluded that CBZ was not directly responsible for the malformations. The identity of the teratogenic contaminant is not known at this time, but is unlikely to be a DBP or low concentrations of the pharmaceutical carbamazepine.
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    Quaternary Ammonium Compound Disinfectants Reduce Lupus-Associated Splenomegaly by Targeting Neutrophil Migration and T-Cell Fate
    Abdelhamid, Leila; Cabana-Puig, Xavier; Mu, Qinghui; Moarefian, Maryam; Swartwout, Brianna K.; Eden, Kristin; Das, Prerna; Seguin, Ryan P.; Xu, Libin; Lowen, Sarah; Lavani, Mital; Hrubec, Terry C.; Jones, Caroline N.; Luo, Xin M. (2020-10-21)
    Hypersensitivity reactions and immune dysregulation have been reported with the use of quaternary ammonium compound disinfectants (QACs). We hypothesized that QAC exposure would exacerbate autoimmunity associated with systemic lupus erythematosus (lupus). Surprisingly, however, we found that compared to QAC-free mice, ambient exposure of lupus-prone mice to QACs led to smaller spleens with no change in circulating autoantibodies or the severity of glomerulonephritis. This suggests that QACs may have immunosuppressive effects on lupus. Using a microfluidic device, we showed that ambient exposure to QACs reduced directional migration of bone marrow-derived neutrophils toward an inflammatory chemoattractant ex vivo. Consistent with this, we found decreased infiltration of neutrophils into the spleen. While bone marrow-derived neutrophils appeared to exhibit a pro-inflammatory profile, upregulated expression of PD-L1 was observed on neutrophils that infiltrated the spleen, which in turn interacted with PD-1 on T cells and modulated their fate. Specifically, QAC exposure hindered activation of splenic T cells and increased apoptosis of effector T-cell populations. Collectively, these results suggest that ambient QAC exposure decreases lupus-associated splenomegaly likely through neutrophil-mediated toning of T-cell activation and/or apoptosis. However, our findings also indicate that even ambient exposure could alter immune cell phenotypes, functions, and their fate. Further investigations on how QACs affect immunity under steady-state conditions are warranted.