Molecular mechanisms of wound healing have been extensively characterized, providing a better understanding of the processes involved in wound repair and offering advances in treatment methods. Both spatial and temporal investigations of injury biomarkers have helped to pinpoint significant time points and locations during the recovery process, which may be vital in managing the injury and making the appropriate diagnosis. This study addresses spatial and temporal differences of phosphoproteins found in skeletal muscle tissue following a traumatic femur fracture, which were further compared to co-localized cytokine responses. In particular, several proteins (Akt, ERK, c-Jun, CREB, JNK, MEK1, and p38) and post-translational phosphorylations (p-Akt, p-c-Jun, p-CREB, p-ERK1/2, p-MEK1, p-p38, p-GSK3α/β, p-HSP27, p-p70S6K, and p-STAT3) associated with inflammation, new tissue formation, and remodeling were found to exhibit significant spatial and temporal differences in response to the traumatic injury. Quadratic discriminant analysis of all measured responses, including cytokine concentrations from previously published findings, was used to classify temporal and spatial observations at high predictive rates, further confirming that distinct spatiotemporal distributions for total protein, phosphorylation signaling, and cytokine (IL-1α, IL-1ß, IL2, IL6, TNF-α, and MIP-1α) responses exist. Finally, phosphoprotein measurements were found to be significantly correlated to cytokine concentrations, suggesting coordinated intracellular and extracellular activity during crucial periods of repair. This study represents a first attempt to monitor and assess integrated changes in extracellular and intracellular signaling in response to a traumatic injury in muscle tissues, which may provide a framework for future research to improve both our understanding of wounds and their treatment options.

Thousands of gallons of industrial chemicals, crude 4-methylcyclohexanemethanol (MCHM) and propylene glycol phenyl ether (PPh), leaked from industrial tanks into the Elk River in Charleston, West Virginia, USA, on January 9, 2014. A considerable number of people were reported to exhibit symptoms of chemical exposure and an estimated 300,000 residents were advised not to use or drink tap water. At the time of the spill, the existing toxicological data of the chemicals were limited for a full evaluation of the health risks, resulting in concern among those in the impacted regions. In this preliminary study, we assessed cell viability and plasma membrane degradation following a 24-h exposure to varying concentrations (0-1000 μM) of the two compounds, alone and in combination. Evaluation of different cell lines, HEK-293 (kidney), HepG2 (liver), H9c2 (heart), and GT1-7 (brain), provided insight regarding altered cellular responses in varying organ systems. Single exposure to MCHM or PPh did not affect cell viability, except at doses much higher than the estimated exposure levels. Certain co-exposures significantly reduced metabolic activity and increased plasma membrane degradation in GT1-7, HepG2, and H9c2 cells. These findings highlight the importance of examining co-exposures to fully understand the potential toxic effects.

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The phenomenon of hormesis, characterized by beneficial low-exposure stress-protective effects, has experienced increasing interest by the scientific community. Elucidating the underlying cellular signaling pathways that lead to a new homeostatic state can provide crucial information about new therapeutic targets to prevent and treat diseases. Commonly investigated for hormetic behavior are plant-based substances (phytochemicals), such as quercetin, epigallocatechin gallate, curcumin, and resveratrol. The polyphenol resveratrol, found in peanuts, grapes, and subsequently in wine, is known for a variety of effects-beneficial and detrimental-depending on the investigated cell type and concentration. In HepG2 cells, an increase in proliferation has been observed previously at doses between 10 µM to 100 µM after 16 hours, while higher doses decreased cell viability markedly, eventually leading to cell death. For other compounds, literature searches provide conflicting data on the hormetic capabilities and subsequently on the associated concentrations. This work aims to clarify the concentration and exposure duration dependence in hormesis. The four aforementioned compounds were screened for their hormetic behavior in a human liver cancer model by assessing the effects of varying concentrations on metabolic activity and plasma membrane integrity. Quercetin, epigallocatechin gallate, and curcumin did not show hormetic properties in the investigated concentration range during a 24-hour exposure. Resveratrol qualified for further experiments where cells were subjected to 0.1 to 500 µM for six, twelve, 24, 48, and 72 hours. A significant change in metabolic activity at concentrations of 50, 100, and 250 µM was found between twelve and 24 hours, as well as a significant increase in plasma membrane degradation after 24 hours at doses higher than 100 µM. This demonstrates a noticeable change in cellular behavior between the twelve-and 24-hour mark, associated with resveratrol concentrations from 50 to 250 µM. Future research should include real-time assessment of energy markers, preferably up to 24 hours, to pinpoint timepoints of metabolic switches, and subsequently study the changes that underlie hormesis at these timepoints. iii DEDICATION This thesis is dedicated to Katharina Brylla, an extraordinary women, mother, and grandmother. She persisted through unimaginable adversities in the darkest times of European history without losing herself. Not everyone can live a happy and productive life after these experiences and enjoy the small things in life, including advocaat and "Mensch Ärgere Dich Nicht". She was the inspiration for long days and short nights in the hope of spending a few more joyful moments in her presence after graduation. Unfortunately, I was too late. iv v ACKNOWLEDGEMENTS Firstly, I thank Dr. Jonathan Boyd for his advisory patience over the past two and a half years. Our shared work has taught me a great deal about myself, science, life, the importance of integrity, and the nature of academia. I am gratef...