A Chemical Genetic Strategy to Study Vip1 in Inositol Pyrophosphate Signaling

The water-soluble and highly phosphorylated inositol pyrophosphates (PP-IPs) are a conserved class of signaling molecules. Genetic studies in yeast have implicated the PPIPs in a variety of roles, including nutrient sensing and response to environmental stress, but have largely proven ineffective in decoding their mechanisms of action. This thesis focuses on developing a chemical genetic approach for an in-depth analysis of the signaling roles of Vip1, an ATP-grasp kinase, and its corresponding PP-IP products in Saccharomyces cerevisiae. The technique relies on strategically introducing mutations into the kinase active site and developing orthogonal ATP analogs. I report the successful identification and engineering of analog sensitive alleles of Vip1 (Vip1-AS) that maintain functionality both biochemically and in yeast. Furthermore, I use a structure-guided approach to develop a small class of biorthogonal ATP-competitive pyridopyrimidines, and demonstrate their potency against and selectivity for Vip1-AS in vitro. Though inhibition studies in yeast are thus far incomplete, preliminary results provide promising evidence for the successful creation of an appropriate chemical genetic system for Vip1. Once verified and optimized, the system can be not only applied to investigate Vip1¿s role in transcriptional and metabolic regulation, but also extended to examine homologues in higher-order eukaryotes and structurally similar enzymes within the ATPgrasp superfamily

Influence of Surfactant-Nanoparticle Interactions on Emulsion Behavior with Applications to Flow Assurance

Emulsions have wide industrial applications such as those in paints, cosmetics, food, energy, and pharmaceuticals. The surfactant-nanoparticle interactions play a critical role in determining the stability of the interfacial film. My research aims at probing the fundamental mechanisms governing the surfactant-nanoparticle interactions at the fluid-fluid interface and the consequence of surfactant-nanoparticle interactions on the stability and rheology of emulsions. My research consisted of four parts: a) probing the influence of nanoparticle addition to surfactant-stabilized emulsions b) elucidating the effect of surfactant addition to nanoparticle-stabilized emulsions c) investigating the influence of surfactant-nanoparticle interactions on the behavior of oil-in-oil emulsions d) examining the influence of surfactant-nanoparticle interactions and nanoparticle wettability on hydrate formation.Literature shows that the presence of both surfactants and nanoparticles enhance emulsion stability. On the contrary, our data showed that the addition of silica nanoparticles to surfactant-stabilized emulsions could lead to destabilization of water-in-oil emulsions. Partially hydrophobic silica nanoparticles had higher destabilization efficiency as compared to hydrophilic and hydrophobic silica nanoparticles.Our results showed that the addition of surfactants significantly influenced the droplet size of Pickering emulsions depending on the wettability of nanoparticles at the liquid-liquid interface. For water-in-oil emulsions stabilized using hydrophobic nanoparticles, there was a significant decrease in the droplet size upon the addition of a surfactant. On the contrary, for water-in-oil emulsions stabilized using partially hydrophobic nanoparticles, no significant change in the droplet size was observed upon the addition of a surfactant. Based on our data, we postulate that the addition of a non-ionic surfactant aided in partial displacement of hydrophobic nanoparticles from the oil-water interface unlike partially hydrophobic nanoparticles, which in turn affected the droplet size of emulsions.Furthermore, our results showed that simultaneous emulsification using hydrophobic nanoparticles and a surfactant (either Span 80 or Triton X-100) resulted in a single-step formation of multiple oil-in-oil-in-oil (O/O/O) emulsions. Multiple O/O/O emulsions had lower viscosity when compared to simple oil-in-oil (O/O) emulsions. Simple O/O emulsions had a lower degree of shear thinning behavior when compared to multiple O/O/O emulsions.In addition, our results showed that nanoparticle wettability influenced the formation and rheology of hydrates in water-in-oil emulsions

Acute Suppurative Thyroiditis in an Intravenous Drug User with a Preexisting Goiter

Acute suppurative thyroiditis (AST) is an uncommon, potentially life-threatening cause of a rapidly enlarging neck mass. It may present similarly to subacute thyroiditis, a relatively benign and self-limiting condition. We report a case of AST in an adult intravenous (IV) drug user with a preexisting goiter who presented with a left forearm abscess that grew methicillin-sensitive Staphylococcus aureus. In this particular case, clinical suspicion for AST was high. As a result, early IV antibiotic therapy was initiated, and this led to rapid clinical improvement furthermore preventing airway compromise. To our knowledge, this is the first case of AST in the literature resulting from likely hematogenous spread in the setting of IV drug use and a preexisting goiter. Overall, this case highlights the importance of assessing risk factors for AST in patients whose presentations may seem more typical of subacute thyroiditis. Such an approach will lead to timely diagnosis and treatment to avoid potentially devastating consequences

Demulsification of Surfactant-Stabilized Water-in-Oil (Cyclohexane) Emulsions using Silica Nanoparticles

Efficient phase separation of oil and water in emulsions is critical for water treatment and hydrocarbon processing. Our research aims at elucidating the separation of water-in-oil emulsions using silica nanoparticles (SNPs). By probing the surfactant–nanoparticle interactions, we show that surfactant-stabilized emulsions can be destabilized depending on the nanoparticle wettability and the mode of nanoparticle addition. The efficiency of nanoparticles to demulsify surfactant-stabilized emulsions depended on both the nanoparticle and surfactant concentration. Water-in-oil emulsions were destabilized when partially hydrophobic nanoparticles were added to the surfactant-stabilized emulsion after emulsion formation (post-mixing). Hydrophilic and partially hydrophobic nanoparticles adsorb the surfactants via hydrogen bonding which in turn leads to depletion of surfactants at the oil–water interface. Upon the addition of hydrophilic nanoparticles, the preferential distribution of nanoparticles in the water phase led to lower adsorption of surfactants from the oil phase, resulting in inefficient destabilization as compared to that of partially hydrophobic nanoparticles. Water-in-oil emulsions were not destabilized upon post-mixing hydrophobic nanoparticles due to weak hydrophobic interactions between surfactants and hydrophobic nanoparticles. For a fixed concentration of nanoparticles of specific wettability, changing the mode of nanoparticle addition altered the flow behavior and the network strength of surfactant-stabilized water-in-oil emulsions

Radiation Therapy in Metastatic Soft Tissue Sarcoma: From Palliation to Ablation

The management of patients with metastatic cancer is rapidly changing. Historically, radiotherapy was utilized for the treatment of localized disease or for palliation. While systemic therapy remains the mainstay of management for patients with metastatic cancer, radiotherapy is becoming increasingly important not only to palliate symptoms, but also to ablate oligometastatic or oligoprogressive disease and improve local control in the primary site. There is emerging evidence in multiple solid malignancies that patients with low volume metastatic disease that undergo local ablative therapy to metastatic sites may have improved progression free survival and potentially overall survival. In addition, there is increasing evidence that select patients with metastatic disease may benefit from aggressive treatment of the primary site. Patients with metastatic soft tissue sarcoma have a poor overall prognosis. However, there may be opportunities in patients with low volume metastatic soft tissue sarcoma to improve outcomes with local therapy including surgery, ablation, embolization, and radiation therapy. Stereotactic body radiation therapy (SBRT) offers a safe, convenient, precise, and non-invasive option for ablation of sites of metastases. In this review article, we explore the limited yet evolving role of radiotherapy to metastatic and primary sites for local control and palliation, particularly in the oligometastatic setting