Parkinson’s Disease is a disorder of the midbrain dopaminergic system with characteristic neurodegenerative patterns, recognized for its motor symptoms. The neurodegeneration is most prevalent in the substantia nigra pars compacta, while dopaminergic neurons in neighboring structures are comparatively spared. There are many possible explanations for this disparity, including differences in tolerance to oxidative stress, and vulnerability to α-synuclein aggregates. The substantia nigra is part of the basal ganglia, a network of nuclei in the midbrain and base of the forebrain which are responsible for coordinating voluntary movement. Dopamine has an inhibitory effect in the basal ganglia. It dampens signals to remove noise, so the basal ganglia circuitry is not hyperactive. In the absence of dopamine, the flow of information through the basal ganglia is disrupted. This results in tremor, bradykinesia, and rigidity, known as the classic triad. No cure currently exists and therapies are unable to slow disease progression, so treatments are aimed at symptom management. Degenerative processes in Parkinson’s Disease occur rapidly, early in the disease progression, with about 60% neuronal death in the substantia nigra prior to diagnosis. There is a need for biomarkers or other signs which can be used to clinically to diagnose the disease at an earlier stage. In conclusion this paper provides suggestions for future lines of research.

This report from Groote Schuur therefore sets out to review cases of postradiation sarcomas, including malignant mixed mullerian tumors (MMMT), presenting to the Radiation Oncology Departments of Groote Schuur Hospital and the affiliated hospitals (Frere Hospital, East London and Provincial Hospital, Port Elizabeth) or known to have occurred in patients initially treated in these hospitals. It aims [1] to establish the features of the initial malignancy as well as the latent period for the development of postradiation sarcoma, the type of postradiation tumor and the outcome of the disease; [2] to establish as accurately as possible dose levels at which the postradiation tumors have developed; and [3] to briefly describe possible risk factors such as a genetic predisposition to the development of malignancy, repeated courses of radiotherapy, surgery as part of the treatment of the initial tumor, and chemotherapy. Questions regarding the genesis of postradiation sarcomas cannot be answered by a review of 20 cases, even when combined with an analysis of literature. This review aims to add relevant information to the body of data from which the final answers may come. In view of the late diagnosis often made in cases of postradiation sarcoma (25, 94) the review also aims to heighten awareness of the condition so that it may be more often reported at a curable stage.

Diisocyanates (dNCO) such as methylene diphenyl diisocyanate (MDI) are used primarily as cross-linking agents in the production of polyurethane products such as paints, elastomers, coatings and adhesives, and are the most frequently reported cause of chemically induced immunologic sensitization and occupational asthma (OA). Immune mediated hypersensitivity reactions to dNCOs include allergic rhinitis, asthma, hypersensitivity pneumonitis and allergic contact dermatitis. There is currently no simple diagnosis for the identification of dNCO asthma due to the variability of symptoms and uncertainty regarding the underlying mechanisms. Immunological sensitization due to dNCO exposure is traditionally thought to require initial conjugation of the dNCO to endogenous proteins to generate neoantigens, which trigger production of dNCO specific T lymphocytes and ultimately dNCO specific IgE. Testing for dNCO-specific IgE, for diagnosis of dNCO asthma is however, only specific (96-98%) but not sensitive (18-27%). The low prevalence of detectable dNCO specific IgE has been attributed to both assay limitations and a potential IgE-independent dNCO asthma mechanism(s). The identity of the conjugated proteins responsible for the sensitization also remains unknown. It is also not clear whether dNCOs bind to extracellular, cell membrane, or intracellular proteins as a way of triggering non-IgE asthma. Standardization and optimization of immunoassays used to screen for dNCO specific antibodies in sera is important if its utility as a dNCO asthma diagnostic tool is to be achieved. This will potentially improve sensitivity and allow comparison of results across studies. Current studies on assays of dNCO-specific IgE and IgG lack or have limited characterization of the conjugates used. Diisocyanates bound to hemoglobin (Hb), human serum albumin (HSA), and THP-1 proteins were quantified by HPLC with fluorescence detection. Proteomic tandem mass spectrometry (MS) was used to delineate TDI and MDI specific amino acid binding sites on Hb as well as identification of proteins from MDI exposed THP-1 cells. The trinitrobenzene sulfonic acid assay (TNBS) and SDS gel electrophoresis were used to evaluate extent of intra and intermolecular cross-linking in dNCO-HSA conjugates. Binding of monoclonal antibodies (mAbs) to dNCO bound proteins in enzyme-linked immunosorbent assay (ELISA) was used to evaluate antigenicity of dNCO-protein conjugates. The amount of dNCO binding to HSA and Hb increased with the concentration of the dNCO used for conjugation. All the dNCOs reacted with HSA more than with Hb. Eight binding sites were observed with both MDI and TDI on Hb. The N-terminal valines of both the alpha and beta subunits on Hb, lysine 40 of the alpha subunit and lysine 61 of the beta subunit were common binding sites for both TDI and MDI. Lysine 7 of the alpha subunit and lysines 8, 65 and 66 of the beta subunit were unique to MDI. On the other hand, lysines 11, and 16 of the alpha subunit and lysines 17 and 144 of the beta subunit were unique to TDI. Protein bound MDI was detected in a dose-dependent manner in membrane and cytoplasm fractions of MDI exposed THP-1 cells. MDI was also detected in 11 of the 13 cytoplasmic protein bands. The extent of MDI intracellular protein binding was not affected by cytochalasin D, a chemical that binds actin filaments and inhibits active uptake into cells. The extent of cross-linking shown using the TNBS assay was found to increase with amount of dNCO used. Clear bands from both intra and intermolecular cross-linking were observed on all dNCO-Hb/HSA SDS gels. Using ELISA, both TDI-Hb and TDI-HSA conjugates were reactive to monoclonal antibodies produced against TDI conjugated HSA indicating that dNCO-Hb is also antigenic. The best characterization of dNCO-protein conjugates is achieved by the quantitative determination of conjugated dNCO per mole of protein as well as determining the extent of dNCO cross-linking. Although HSA is more reactive to dNCOs than other serum proteins such as Hb, contribution from other serum proteins to development of OA should not be overlooked as dNCO-Hb was found to be reactive to dNCO specific mAbs. dNCO-conjugated proteins identified in the soluble fraction of MDI exposed THP-1 cells were all of intracellular origin suggesting that MDI can cross the cell membrane and react with intracellular proteins. The entry of MDI into live cells is a passive process, as the extent of intracellular binding was not affected by cytochalasin D. The present study support the potential involvement of dNCO-haptenated membrane and intracellular proteins in development of non-IgE dNCO asthma.

Ferroptosis is a regulated junction between cell death, metabolism, and disease, and it hasbeen implicated in many pathologies. The assorted ferroptosis pharmacology modulators offer valuable means to modulate ferroptosis in multiple diseases, to explore disease etiology, and to develop potential therapeutics. In the first part, the work focuses on inhibiting ferroptosis in a Huntington’s disease model. Ferrostatin-1 (Fer-1) is a potent small-molecule ferroptosis inhibitor that has been adopted to investigate the role of ferroptosis in many disease models. However, its further application is limited by its low potency, poor stability, possible toxicity, and lack of brain penetration. We developed the fourth and fifth generations of ferrostatins and investigated the in vitro and in vivo pharmacokinetics of lead compounds. We identified PHB4082 preferentially accumulating in the kidney as a potential candidate for kidney disease-relevant contexts. Moreover, TH-4-55-2 displayed an excellent brain penetration, preferentially accumulating in the brain at concentrations of magnitude higher than the in vitro IC50 values. In the in vivo toxicity study, it was well-tolerated over 30 days in wild-type and R6/2 mice and exhibited a protective effect against weight loss in a Huntington’s disease model, suggesting it is a strong candidate for application in HD and more neurodegenerative disease models. The second part describes the efforts to explore the therapeutic potential of inducing ferroptosis in a tumor model. Imidazole ketone erastin (IKE) induced ferroptosis by specifically inhibiting system xc– in a subcutaneous xenograft model of Diffuse Large B Cell Lymphoma (DLBCL), suggesting the potential of IKE as a therapeutic strategy for cancer. A biodegradable polyethylene glycol-poly (lactic-co-glycolic acid) nanoparticle formulation was used to aid in delivering IKE to cancer cells in vivo, exhibiting improved tumor accumulation and therapeutic index relative to free IKE, indicating its potential for treating DLBCL. In summary, this work explored the possibility to modulate ferroptosis using small molecule modulators in multiple disease models and identified some potential drug candidates and useful chemical probes.

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Climate change is already harming public health through warmer, more erratic weather and many downstream consequences. Research can support climate change adaptation by characterizing climate-related exposures, identifying vulnerable populations, and identifying effective interventions. Furthermore, the main source of greenhouse gas emissions, fossil fuel combustion, also produces air pollutants such as fine particulate matter (PM2.5) that directly harm human health. In this dissertation my colleagues and I have examined the effects of short-term temperature exposure on myocardial infarction and stroke to inform adaption (Chapters 1 to 3) and leveraged multiple exposure models to estimate annual PM2.5 concentrations and quantify uncertainty (Chapter 4). To examine the effects of short-term temperature exposure, we conducted case-crossover analyses using an administrative dataset of hospitalizations in New York State. For PM2.5 prediction and uncertainty characterization, we applied a flexible ensemble approach to leverage seven already-developed PM2.5 models. Overall, we found that warmer hourly temperatures and greater daily temperature variability increased the risk of ischemic events, and lower hourly temperatures increased the risk of hemorrhagic stroke. The ensemble model showed high predictive accuracy, demonstrating the strength of this approach, and we observed greatest uncertainty in the Pacific Northwest and southeast coast. The methods applied in this dissertation can be applied to other exposures and in different settings to further quantify the risks of climate impacts and improve air pollution assessment. Future research should examine the joint impacts of multiple weather factors, strategies to protect people in group housing from extreme weather, measurements and models to reduce uncertainty of air pollution exposures, and propagate exposure uncertainty into health models. However, the need for further research should not delay climate action today.

Indiana University-Purdue University Indianapolis (IUPUI) / Objective: To investigate the effect of the size of the space between the restoration and the dentinal wall of the tooth (i.e. the dentinal portion of the gap) on the development of secondary caries. Methods: Tooth-resin-matrix composite specimens were mounted on custom-made gap-model stages. Specimens were divided into four groups (n=10). Group 1 had a uniform gap size of 30μm throughout both enamel and dentin. Group 2 had a 30μm enamel gap size with a 530μm dentinal gap. Group 3 had 525μm gaps in both enamel and dentin. Group 4 had 525μm and 1025μm gaps in enamel and dentin, respectively. Specimens were attached to plastic Petri plates, gas-sterilized and then incubated in a microbial caries model with S. mutans TH16 in (1% sucrose tryptic soy broth for 1 h, 4 times/day, and with a buffer solution for the rest of the day). After 8 days of incubation, tooth specimens were sectioned and stained with a rhodamine B solution. Digital images were taken under a confocal microscope and analyzed for lesion size at the enamel outer lesion (EOL), enamel wall lesion (EWL), dentin wall lesion next to the DEJ (DWL-A) and dentin wall lesion at 750µm from the DEJ (DWL-B). Results: No difference in EOL size was found between the groups. DWL-A and -B were larger in group 3 than groups 1and 2. Larger DWL-B was found in group 3 than group 4. Group 4 had marginally significant larger EWL than groups 1 and 2 (p=0.0652 and p=0.0648, respectively). Also, group 4 had marginally significant (p=0.0607) larger DWL-B than group 1. Conclusions: Based on the results of this study, it can be concluded that the presence of additional space at the dentinal wall area did not affect secondary caries development as long as the enamel gap was small. However, with enamel gaps of ≈500 µm, the presence of the additional gap space at the dentinal wall led to the development of smaller dentinal wall lesions at the deeper parts of the simulated cavity. Also, in uniform gaps, the size of the interface was positively correlated with size of the dentinal wall lesions.