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Parkinson's disease (PD) is a neurodegenerative Lewy body disorder characterized by severe motor deficits, followed by cognitive dysfunction with progression of the disease. Environmental exposure has been suggested as a possible contributor to the development of PD and this view is linked to the discovery of the nigrostriatal neurotoxin MPTP. MPTP can induce dopamine specific degeneration within the basal ganglia often resulting in motor deficits similar to PD. MPTP used in the C57BL/6 mouse is a widely used animal model of PD. The pyrethroid permethrin (PM), and the organophosphate chlorpyrifos (CPF), can produce changes in dopaminergic nigrostriatal neurons, the primary target of PD and MPTP-induced neurotoxicity. Such insecticide induced changes in the basal ganglia could exacerbate the onset or severity of PD. Chronic exposure to the metal manganese (Mn) can damage the globus pallidus (GP) of the BG, and produce motor deficits similar to PD. Since the GP is part of the BG circuitry essential for motor control, and is synaptically integrated with the nigrostriatal pathway, Mn may exacerbate MPTP-induced neurotoxicity. Because the BG is disynaptically linked to the mesocortical pathway, a dopaminergic pathway that is important for cognition, Mn induced damage in the BG could indirectly affect the mesocortical pathway as well. This study investigated the pesticides, permethrin and chlorpyrifos, and the heavy metal, manganese as possible environmental compounds that could exacerbate PD in the MPTP treated C57BL/6 mouse. The first part of this dissertation used immunohistochemistry to examine insecticide induced effets on MPTP-induced neurotoxicity in the dorsolateral striatum of the C57BL/6 mouse, the principal target of the nigrostriatal pathway. Tyrosine hydroxylase (TH) was used as a marker for loss of dopaminergic neuropil and glial fibrillary acidic protein (GFAP) was used as a marker of glial activation in the striatum. Three experiments assessed effects of 1) PM (200 mg/kg), 2) CPF (50 mg/kg) & 3) PM + CPF, on MPTP (30 mg/kg) neurotoxicity. Immunohistochemistry revealed a decrease in TH staining and an increase in GFAP staining with MPTP (30 mg/kg). A main effect increase in GFAP was observed for PM (200 mg/kg), but not for CPF (50 mg/kg) or PM+CPF. Insecticides, alone or combined, did not alter MPTP-induced toxicity. . However, the absence of the PM-induced increase in GFAP staining following combined insecticide treatment suggests a neuroprotective effect. The next set of experiments in this dissertation looked at the effect of Mn on MPTP-induced neurotoxicity in the nigrostriatal and mesocortical dopaminergic pathways of the C57BL/6 mouse. Inductively Coupled Plasma atomic emission spectrometry revealed striatal Mn levels were significantly increased with multiple dose 100, 50, and 25 mg/kg MnCl2. Administration of Mn (MnCl2 s.c., Days 1, 4, & 7) in the MPTP (20 mg/kg i.p., Day 8) treated C57BL/6 mouse revealed Mn and MPTP interactions for locomotor activity, grip strength, and repeated measures of learning. Mn attenuated the effect of MPTP on striatal DOPAC, and facilitated the effect of MPTP on cortical DA and DOPAC. Mn also attenuated the MPTP induced decrease in cortical DAT. While these data support the notion that insecticides can produce tissue damage in the nigrostriatal pathway, in this case, these insecticide induced changes were not found to be strong enough to facilitate PD-like tissue damage. While Mn did not always facilitate MPTP neurotoxicity in the mesocortical and nigrostriatal dopaminergic pathways, these results demonstrate Mn and MPTP can interact in a complex way to alter dopaminergic function as well as motor and cognitive behavior. Differences in brain uptake mechanisms and metabolism of Mn and MPTP, could explain why combined administration of Mn and MPTP differentially affect dopaminergic activity in the nigrostriatal and mesocortical pathways.

Skin infections by the ectoparasitic mite Sarcoptes scabiei are a preventable source of morbidity worldwide. While scabies affects all socioeconomic sectors, it is especially prominent in the developing world where crowding, poor hygiene, and limited access to basic health care are commonplace. Mass eradication efforts of this parasite have historically been hampered by delivery and compliance issues surrounding topical standards of care. There have been advances in eradication over the last decade due to the expanded use of oral Ivermectin for the treatment and prevention of ectoparasites such as scabies. Previous research focused on various treatment aspects of the disease, yet most identified the need for basic scabies health education to accompany future studies to improve program sustainability and the overall health literacy of target populations. The Virginia College of Osteopathic Medicine sponsors a public health clinic in Veron, Dominican Republic that reports a high prevalence of scabies infections among its general patient population. The lack of any means of direct measurement, proper intervention, or control raises concerns that long-term infection may lead to multiple other secondary disease sequelae. The Veron Scabies Eradication and Education Program was designed to address this deficiency and build on previous studies related to this problem by using a novel treatment and education protocol. The purpose of this research was to identify, treat, and prevent primary and secondary health problems due to long-term scabies infection in the community of Barrio Nuevo, Veron, Dominican Republic in order to provide long-term sustainable eradication through a researcher-designed health education program and medical service protocol. Participants continued typical daily life while interventions and education were monitored to detect change over a 9-month timeline using selected measurement intervals to test multiple scabies disease and knowledge objectives and related hypotheses. Following this basic protocol, the following scabies markers were evaluated at baseline: subject demographics, scabies diagnosis and treatment history, baseline treatments and reported side effects, and scabies education pre-test results. The following scabies markers were also assessed at baseline and reassessed at 2 weeks, 1 month, 2 months, 8 months, and 9 months: risk and prevention behaviors, symptomatology, skin exam findings, and scabies education post-test results. There was a statistically significant post-intervention improvement in scabies markers when compared to pre-intervention values (p

Parkinson's disease (PD) is a debilitating motor disorder that primarily afflicts older individuals (> 50yrs). Although its cause is unknown, many factors are thought to contribute to the disease. There is growing epidemiological evidence supporting a link between pesticide exposure and PD. The present immunohistochemical study was undertaken to characterize the role of insecticide exposure in the etiology of idiopathic PD. The insecticides selected for study were the pyrethroid permethrin (PE) and the organophosphate chlorpyrifos (CP), both of which possess properties that could damage or disrupt the nigrostriatal pathway, which is the principal neurodegenerative target in PD. The present study examined possible alteration of the amount of dopamine re-uptake transporter protein (DAT), within the striatum of the C57BL/6 mouse, using DAT antibodies, following low (0.8, 1.5 & 3.0 mg/kg) and high (200 mg/kg) doses of PE, respectively. Possible nigrostriatal terminal degeneration was examined using antibodies to tyrosine hydroxylase (TH), the rate-limiting enzyme in dopamine synthesis, following treatment with 50 mg/kg of CP alone or in combination with the high dose of PE. For both the high dose of PE alone and for the combined PE/CP treatment, glial fibrillary acidic protein (GFAP) antibodies were used to examine the possibility of non-degenerative tissue injury. Groups of matched treated/vehicle-control mice received three IP injections of the insecticide/dose of interest over a 2-week period. Counts of immunoreactive (IR) neuropil in the dorsolateral striatum were made from four pre-selected fields per striatal tissue section. Counts were compared between matched sections, processed on the same slide, from a treated mouse and its vehicle control. A mean difference score, across slides, for each treated/vehicle control pair was determined. All low dose PE groups showed a trend of decreased DAT IR neuropil, but only the 3.0mg/kg group showed a statistically significant reduction (p

The present study examined adverse effects of sunlight exposure (mimicked by intradermal cis-urocanic acid, cUCA) on local and systemic immune responses, with or without co-exposure to the immunotoxic insecticide permethrin. A single exposure to cUCA caused diminished splenic macrophage phagocytosis that was persistent up to 30 days post-exposure. Five-day exposure to cUCA subtly increased splenocyte proliferation in response to the T cell mitogen Concanavalin A. Four-week exposure to cUCA caused increased splenic lymphocyte cellularity, thymic hypocellularity, and enhanced hydrogen peroxide production by splenic leukocytes. Single exposure to topical permethrin resulted in decreased thymic and splenic weight and cellularity, and inhibited antibody production by splenic B cells. cUCA worsened the negative effect of permethrin on both thymic weight and cellularity, and depressed splenocyte blastogenesis, hydrogen peroxide production, and antibody production. Five-day exposure to either cUCA or permethrin also caused persistent decreased contact hypersensitivity responses, an effect that became more than additive when the chemicals were administered concurrently. Defects in antigen processing and presentation by cutaneous Langerhans cells were evaluated as possible contributing mechanisms to the cutaneous immunosuppression, using mice with deleted genes. Vehicle-exposed IFNg knockout mice displayed approximately a 22.1% depression in the ear swelling response as compared to control C57BL/6N mice, suggesting that this cytokine may be required for mounting a control-level hypersensitivity response. Ear swelling in cUCA-exposed IFNg knockout mice displayed a 21.4% depressed response as compared to cUCA-exposed wild-type C57BL/6N mice, again suggesting that IFNg is an important cytokine in the contact hypersensitivity (CH) response. TNFaR knockout mice exposed to cUCA displayed 33.9% greater ear swelling than cUCA-exposed wild-type C57BL/6N mice, suggesting that increased TNFa may be involved in inhibited CH by cUCA. TNFaR knockout mice exposed to permethrin displayed 33.9% greater ear swelling than permethrin-exposed C57BL/6N mice, suggesting that increased TNFa may also be involved in inhibited CH by permethrin. C57BL/6N mice exposed to cUCA + permethrin displayed severe reduction of the CH response to 8.7% of the control level. IFNg knockout mice exposed to permethrin + cUCA showed essentially identical depression of the CH response as IFNg knockout mice exposed to either permethrin or cUCA alone. These results suggest that IFNg is required for the greater than additive immunotoxic effect that occurred when these two agents were co-administered. TNFaR knockout mice exposed to cUCA + permethrin displayed 8.7 fold greater ear swelling than similarly exposed C57BL/6N mice, again suggesting that increased TNFa is involved in inhibited CH by both cUCA and permethrin.

The immunotoxic effects of multiple pesticide exposure were evaluated. C57BL/6 mouse thymocytes were exposed to lindane, malathion, and permethrin, either separately or in mixtures of two pesticides, in concentrations ranging from 37.5 uM to 1mM. These exposures caused both apoptotic and necrotic cell death in thymocytes as evaluated by 7-aminoactinomycin-D, Annexin-V/PI, and lactate dehydrogenase release assays. When cells were exposed to lindane+malathion, or lindane+permethrin, a significantly greater-than-additive cytotoxicity was observed. The pesticide exposure caused DNA ladder formation with increased laddering in mixtures. Further, the effect of these pesticides on thymocyte oxidative stress was investigated. Thymocytes treated with any of these pesticides generated superoxide and H2O2. The lindane + malathion caused more-than-additive increase in superoxide production compared to single treatments of these pesticides. However, the effect of the lindane + permethrin was not significantly different from individual components of this mixture. The effects of pesticides on antioxidant enzymes were also investigated and only mixtures were found to have significant effects. Alteration in transcription factor NFkB level was measured as an indicator of oxidative stress in thymocytes following 12 h pesticide exposure, in vitro. Only lindane + malathion was found to increase the protein level. Furthermore, the effects of pesticides and their mixtures on immune functions of mice were studied in vivo. Animals (8-12 week old, male mice) were randomly divided into groups of six and injected intraperitoneally with three different doses (one-half, one-third, one-fourth, or one-eight of LD50) of individual pesticides. Exposure to individual pesticides did not alter the thymus/body or spleen/body weight ratios, thymic or splenic cell counts, or CD4/CD8 or CD45/CD90 ratios. However, anti-sRBC plaque forming cell (PFC) counts were significantly lowered with all treatments. Two other groups of animals were injected with lindane + malathion or lindane + permethrin at one-third of the LD50 of each pesticide. Exposure to pesticide mixtures did not alter the CD4/CD8 or CD45/CD90 ratios. However, the thymus/ and spleen/body weight ratios, thymic and splenic cell counts, and PFC counts were significantly lowered. These data indicate that lindane, malathion, and permethrin are immunotoxic and their mixtures can cause higher toxicity compared to individual exposures. In addition, these data support the hypothesis that oxidative stress were induced in thymocytes by exposure to these pesticides in vitro.

Inhibited immune responses have been observed following occupational, inadvertent, or therapeutic exposure to chemically diverse xenobiotics. In the present studies, preliminary data were generated showing limited but significant systemic immunotoxicity following low-level topical exposure to the pyrethroid insecticide, permethrin (formerly not considered an immunotoxicant). Permethrin was applied to the shaved dorsal interscapular region of C57Bl/6N mice at doses of 0.5, 1.5, or 5.0 μl/day. The highest of these doses was approximately equal to 215 μg/kg/day, which is about seven times the estimated daily human exposure in individuals wearing permethrin treated clothing for insect protection. Mice were thus exposed to permethrin daily for 10 or 30 consecutive days, or every other day for 7 or 14 exposures. Body weight was not affected by the treatment. However thymic weight was decreased and splenic weight increased 2 days after termination of the topical exposure. Histopathology of immune organs showed no significant changes. Splenic macrophages showed significantly depressed chemiluminescent responses up to 10 days following termination of exposure, but macrophage phagocytic activity was not affected. Cell surface markers of thymocytes, splenocytes and bone marrow cells were not affected. Antibody production as shown by plaque forming cell (PFC) assay decreased significantly at 10 days after dosing termination. Taken together, these data indicate that low-level topical permethrin exposure may produce systemic immunotoxicity.