Metal-binding polymesr as chelating agents

Abstract Metal chelating polymers are functional polymers that bear specified chemical groups capable of selectively binding metals. Heavy metal contamination is considered a serious problem because these metals, even at relatively low concentration, could accumulate in the human body and cause damage to vital organs. Although, some of these metals like iron, zinc, and manganese participate in controlling various metabolic and signaling pathways, an excess amount of these metals could still lead to toxicity and detrimental side effects. Metal chelating polymers are frequently used as chelating agents when treating metal toxicity such as iron overload diseases. Siderophores are small, high-affinity iron chelators secreted by microorganisms such as bacteria. The objective of this thesis was to emulate the high affinity, siderophore-mediated iron uptake system of bacteria by mimicking the structure of naturally occurring siderophores, such as enterobactin. First, polyallylamine (PAAm) hydrogels containing 2,3 dihydroxybenzoic acid (2,3 DHBA), a portion of the metal chelating domain of enterobactin, were synthesized as a potential non-absorbed chelator for iron in the gastrointestinal tract. Next, a series of polymeric chelators with various hydrogel:DHBA ratios were prepared. PAAm hydrogels were also synthesized and further modified by conjugating thioglycolic acid (TGA) and DHBA. These hydrogels were utilized for the removal of toxic metal ions such as Pb, Cd and As from aqueous environments. The rapid, high affinity binding of toxic metals by these functionalized hydrogels offers potential applications in waste water treatment and may enable applications in acute metal poisoning. Finally, a unique synthetic methodology using similar metal chelating polymers for synthesizing magnetic nanoparticles offered potential for contrast-enhanced magnetic resonance imaging or drug delivery. In summary, polymers offer an attractive platform for mimicking siderophore structure which provides new approach for applications in medicine explored here

Essays In Health Economics

Opioid abuse is currently the most significant public health problem in the US. Many US states have implemented prescription drug monitoring programs (PDMPs) in response. In the rst paper, I use a new micro-level medical claims database to exploit state-level and time-series variations in PDMP implementation and shed light on the impacts of these programs. My results show that PDMPs have led to an overall 14% reduction in the odds ratio of abuse/addiction. Also, there is evidence of substantial heterogeneity in impacts, with larger impacts for females and minorities. Another nding is that at least 23% of opioid abuse is a result of drug diversion to nonmedical opioid users. PDMPs were not successful in decreasing the rate of abuse for this group, and, in fact, there is some evidence that they increased the diversion to heroin. Finally, I show that PDMPs\u27 eectiveness varies by type of insurance and that they are more eective in reducing abuse rates in the general population as compared with Medicare Part D recipients. I use my estimates to analyze the potential eects of modifying PDMPs to include giving insurance providers access to electronic databases, providing educational programs for less-educated people, and expanding their \must access requirement. In the second chapter, I estimate dierent models for opioid demand and compare their performance. My results suggest that the NB2 and Poisson FE models best match the data. Using these models for calculating the marginal effect of insurance characteristics provides suggestive evidence of the best insurance design to reduce the demand for opioids

In Situe Synthesis of Iron Oxide within Polyvinylamine nanoparticles

Magnetic nanoparticles that display high saturation magnetization and high magnetic susceptibility with a size less than 200 nm are of great interest for medical applications. Investigations of magnetic nanoparticles have been increasing over the last decade. Magnetite nanoparticles are particularly desirable since the biocompatibility of these particles has already been proven. Several synthetic and natural polymers have been employed to stabilize magnetite nanoparticles and enhance their function in vivo. The goal of this work has been to develop a unique methodology for synthesizing magnetite within polymer nanoparticle dispersions so that the resultant magnetite-polymer particles may be used in a range of biomedical applications, specifically as an MRI contrast agent. A method was developed for preparing ≈150 nm polyvinylamine (PVAm) nanoparticles containing iron oxide. These polymeric nanoparticles offer colloidal stability and reactive primary amines for drug conjugation or surface modification. The polymer-magnetite nanoparticles described in this thesis exhibited a maximum of 12% wt. magnetite and a saturation magnetization of ~30 emu/mg. Transmission electron microscopy (TEM) images showed that the dispersions contained ≈100 to 150 nm diameter PVAm nanoparticles incorporated with iron oxide particles with a size less than ≈10 nm. The ability to synthesize iron oxide inside functionalized polymeric nanoparticles offers an effective approach to prevent nanoparticle agglomeration and the potential to enable ligand grafting. Stabilized magnetic PVAm nanoparticles may provide a unique synthetic approach to enhance MRI contrast and may offer a platform for molecular imaging

Algorithms for Mappings and Symmetries of Differential Equations

Differential Equations are used to mathematically express the laws of physics and models in biology, finance, and many other fields. Examining the solutions of related differential equation systems helps to gain insights into the phenomena described by the differential equations. However, finding exact solutions of differential equations can be extremely difficult and is often impossible. A common approach to addressing this problem is to analyze solutions of differential equations by using their symmetries. In this thesis, we develop algorithms based on analyzing infinitesimal symmetry features of differential equations to determine the existence of invertible mappings of less tractable systems of differential equations (e.g., nonlinear) into more tractable systems of differential equations (e.g., linear). We also characterize features of the map if it exists. An algorithm is provided to determine if there exists a mapping of a non-constant coefficient linear differential equation to one with constant coefficients. These algorithms are implemented in the computer algebra language Maple, in the form of the MapDETools package. Our methods work directly at the level of systems of equations for infinitesimal symmetries. The key idea is to apply a finite number of differentiations and eliminations to the infinitesimal symmetry systems to yield them in the involutive form, where the properties of Lie symmetry algebra can be explored readily without solving the systems. We also generalize such differential-elimination algorithms to a more frequently applicable case involving approximate real coefficients. This contribution builds on a proposal by Reid et al. of applying Numerical Algebraic Geometry tools to find a general method for characterizing solution components of a system of differential equations containing approximate coefficients in the framework of the Jet geometry. Our numeric-symbolic algorithm exploits the fundamental features of the Jet geometry of differential equations such as differential Hilbert functions. Our novel approach establishes that the components of a differential equation can be represented by certain points called critical points

The Effect of Muscle Relaxation on Serum Calcium and Phosphorus Levels in Patients Undergoing Hemodialysis

Improvement of calcium and phosphorus level isconsidered as an important factor in reducing mortalityin hemodialysis patients. This study aimed toinvestigate the effect of muscle relaxation techniques oncalcium, phosphorus and phosphorus concentrations inpatients undergoing hemodialysis. A total of 90 hemodialysispatients in Zahedan hemodialysis centers were selectedby purposive sampling and randomly divided intocontrol and test groups with permutation blocks. Serumlevels of calcium and phosphorus were measured beforethe intervention. Benson’s muscle relaxation responsewas taught to the test group during three sessions andthey were asked to perform relaxation techniques for2-15 times each day for one month. The routine caregroup was provided. Then, the levels of calcium andphosphorus were compared in two groups and the datawere analyzed using statistical tests at a significance levelof 0<0.05. The results showed that the mean of calciumin the test group before and after the intervention was8.69±1.8.1 and 8.79±0.95, respectively. Independent ttestshowed that the mean of calcium after the interventionin the test group was significantly higher than thecontrol group (p=0.005). The mean of p-value before andafter the intervention in the two groups was not statisticallysignificant (P≤0.05). Regarding the improvement ofcalcium level to protect patients against complicationscaused by disorders of these indices, teaching this techniquein hemodialysis sections is recommended

Real solution of DAE and PDAE System

General systems of differential equations don\u27t have restrictions on the number or type of equations. For example, they can be over or under-determined, and also contain algebraic constraints (e.g. algebraic equations such as in Differential-Algebraic equations (DAE) and Partial differential algebraic equations (PDAE). Increasingly such general systems arise from mathematical modeling of engineering and science problems such as in multibody mechanics, electrical circuit design, optimal control, chemical kinetics and chemical control systems. In most applications, only real solutions are of interest, rather than complex-valued solutions. Much progress has been made in exact differential elimination methods, which enable characterization of all hidden constraints of such general systems, by differentiating them until missing constraints are obtained by elimination. A major problem in these approaches is related to the exploding size of the differentiated systems. Due to the importance of these problems, we outline a Symbolic-Numeric Method to find at least one real point on each connected component of the solutions set of such systems