Now showing items 41-60 of 255

    • Use of Antipsychotics in Medicare Part D: The Role of Coverage Restrictions and Impact of Medication Adherence on Hospitalization and Spending For Beneficiaries with Serious Mental Illness

      Roberto, Pamela; Stuart, Bruce C. (2016)
      Background: Coverage restrictions for antipsychotics are associated with access problems in Medicaid but their impact in Medicare Part D is unknown. The relationship between antipsychotic adherence, hospitalization risk, and treatment costs among Part D enrollees with serious mental illness also has not been systematically examined. Evaluating the association between adherence and outcomes is complicated by a recent policy change requiring the redaction of substance abuse claims from the Medicare research files, as hospitalizations and spending for beneficiaries with serious mental illness-many of whom have comorbid substance abuse disorders-may be systematically underreported. Methods: Enrollment, formulary, utilization, and spending data were obtained from the CMS Chronic Conditions Warehouse for 2011-2012. Effects of coverage restrictions on antipsychotic utilization were assessed by exploiting a unique natural experiment in which low-income beneficiaries were randomly assigned to prescription drug plans with varying levels of formulary generosity. The scope of the substance abuse claims redaction was determined by comparing unredacted beneficiary-level expenditure data to expenditures calculated from the redacted claims. Antipsychotic adherence was measured by the proportion of days covered (PDC) and stratified into four categories: PDC<0.70; 0.70≤PDC<0.80; 0.80≤PDC<0.90; and PDC≥0.90. Probit regressions and two-part generalized linear models were used to examine relationships between adherence in year one and hospitalizations and expenditures, respectively, in year two. Results: Despite considerable variation in the use of coverage restrictions across Part D plans, there was no evidence that restrictions significantly altered utilization patterns or reduced overall utilization of antipsychotics. Nearly one in five Part D enrollees with serious mental illness had claims affected by the redaction and average Part A spending among those with redacted claims was underreported by 57%. Based on analysis of the unredacted data, adherence to antipsychotic therapy was associated with significantly lower probability of psychiatric hospitalization and lower hospital expenditures. Conclusions: Coverage restrictions do not limit access to antipsychotics among Part D enrollees. Benefits of sustained adherence to antipsychotics for beneficiaries with serious mental illness include lower probability of psychiatric hospitalization and lower hospital spending. Researchers should exercise caution when using redacted Medicare claims to analyze utilization and spending outcomes for this population.
    • Analysis of Surfactant-mediated Dissolution Effects in Biorelevant Media

      Raman, Siddarth; Polli, James E. (2016)
      Food is known to impact drug bioavailability through a variety of mechanisms, including drug solubilization and prolonged gastric residence time. In vitro dissolution media that aim to mimic in vivo gastrointestinal (GI) conditions have been developed to lessen the need for fed human bioequivalence studies. The first aim of this work was to develop an in vitro lipolysis model to predict positive food effect of three BCS Class II drugs (i.e. danazol, amiodarone and ivermectin) in previously developed lipolysis media. The in vitro lipolysis model accurately predicted the in vivo positive food effect for three model BCS class II drugs. The in vitro lipolysis model has potential use as a screening test of drug candidates in early development to assess positive food effect. In vitro lipolysis is an in vitro approach to simulate drug dissolution under fed conditions, in an effort to anticipate when food increases the absorption of poorly water soluble drugs in vivo due to increased drug solubilization. Imaging techniques have promise to aid in understanding such positive food effects. The second aim of this work was to employ cryogenic transmission electron microscopy (cryo-TEM) to characterize the colloidal changes in Fe-Lipolysis during drug dissolution, and correlate food-enhanced dissolution with colloid structures. Danazol was selected as a model BCS Class II drug with a positive food effect. Danazol samples from fed and fasted state dissolution experiments were subjected to cryo-TEM. Compared to the fed state observations, no major changes were observed in the fasted state. These findings concur with in vivo observations and previously developed hypothetical models of lipolysis and drug solubilization. The third aim of the work was to develop a better understanding of surfactant-mediated dissolution effects in biorelevant media. Three poorly soluble drugs, ciprofloxacin HCl, ivermectin and fexofenadine HCl, that differed in their lipophilicity were analyzed using biorelevant dissolution in human as well as canine fasted state intestinal media. The main objective was to compare the rate and extent of dissolution between these drugs and further elucidate the surfactant-mediated enhancements they experienced. Ivermectin displayed significantly slower dissolution than ciprofloxacin HCl and fexofenadine HCl. Using previously derived models of surfactant-mediated dissolution enhancement, it was determined that ivermectin was heavily dependent on the presence of surfactant, while ciprofloxacin and fexofenadine dissolution showed no dependence on the presence of surfactant as a result of being heavily surfactant-independent.
    • Iron-Regulated Production of Antimicrobial Metabolites by Pseudomonas aeruginosa

      Nguyen, Angela; Oglesby-Sherrouse, Amanda G. (2016)
      Cystic fibrosis (CF) is a hereditary disease characterized by the accumulation of thick, viscous mucus in the lungs. CF disease results in decreased pulmonary function and makes patients prone to chronic bacterial infections. The CF lung is a polymicrobial environment and includes many bacterial species. Early infection with Staphylococcus aureus is common, while Pseudomonas aeruginosa becomes the dominant pathogenic resident as disease progresses. This shift in microbial populations is still not well understood, but the ability of pathogens to obtain limiting nutrients, such as iron, may play a role. The work in this dissertation employed metabolomics, genetics, and biochemical approaches to show that P. aeruginosa alters its iron uptake mechanisms over the course of CF lung infection to adapt to the changing environment of the CF lung and to maintain iron homeostasis. Furthermore, I show that depletion of iron, an essential nutrient for P. aeruginosa growth and survival, enhances antimicrobial activity of this pathogen against S. aureus. I show that iron not only regulates the production of antimicrobial metabolites by P. aeruginosa, but also impacts the susceptibility of S. aureus to the effects of these metabolites. This work has expanded on the knowledge of how iron availability impacts polymicrobial interactions and the progression of CF lung disease.
    • Osteoporosis Medication Use, Adherence, and Outcomes in Elderly Enrolled in Medicare Part D

      Loh, Feng-Hua; Stuart, Bruce C. (2016)
      Background: Osteoporosis affects an enormous number of people of both sexes, and osteoporosis-related fractures are costly to treat. Yet osteoporosis is poorly managed and managed differently by sex and residential setting. Therefore, this study aimed to assess the difference in medication use, adherence, and outcomes between men and women and among women, between long-term care (LTC) facility and community residents. Methods: Using the 2006-2008 Chronic Condition Data Warehouse 5% national random sample of Medicare beneficiaries, this retrospective study identified elderly 70 years and older with osteoporosis enrolled in Medicare Part A, B, and D stand-alone prescription drug plans from January 1, 2006 through December 31, 2008, or death. Use of bisphosphonates, calcitonin, parathyroid hormone and selective estrogen receptor modulator was tracked over the 3-year period. Treatment effectiveness was measured as hazard of fracture after treatment initiation. Modified Poisson regression was used for analyzing the effect of sex and residential status on osteoporosis medication use. Cox proportional hazard model was used for analyzing the effect of medication use and adherence on fracture risk. Results: The samples included 96,408 females, 8,465 males and 90,956 females, and 2,083 males and 10,262 females enrolled in Medicare Part D for aims 1, 2, 3, respectively. Utilization was lower among LTC residents (RR 0.89, 95% CI [0.87, 0.91]). Bisphosphonates were prescribed less often to LTC residents (RR 0.79, 95% CI [0.75, 0.83]) compared to among community residents. Prevalence of osteoporosis medication use in men was substantially lower than that in women (25.2% vs. 44.3% in 2006). Good adherence decreased the hazard of fracture in both sexes (HR 0.86, 95% CI [0.75, 0.99]). No difference in either treatment or adherence effect on fracture between men and women existed. Conclusion: Prevalence of osteoporosis medication use is low in elderly women enrolled in Part D whether community dwelling or LTC residents. Elderly men are undertreated for osteoporosis compared to elderly women. There is strong confounding by indication in the effect of osteoporosis medications on the risk of fracture; however, good adherence reduces the risk of fracture. There is no evidence for heterogeneity in treatment response among men and women.
    • Inhibition of Anti-Apoptotic Protein MCL-1 and Epigenetic Reader BRD4 with Small Molecule Inhibitors: Structure-Based Drug Design and Polypharmacology

      Chen, Lijia; Fletcher, Steven; 0000-0002-5721-5091 (2016)
      One of the hallmarks of cancer is the evasion of programmed cell death. Programmed cell death is strictly regulated by the intrinsic apoptosis pathway, in which BCL-2 anti/pro-apoptotic proteins play vital roles. In normal cells, the delicate balance between anti-apoptotic BCL-2 proteins and their functional sequester: pro-apoptotic proteins, is precisely maintained to ensure the execution of cell death or cell proliferation. However, the apoptotic pathway is often dysregulated in cancer cells, demonstrated by the frequent observed over-expression of anti-apoptotic protein(s), such as BCL-2, BCL-xL and MCL-1. Therefore, targeted inhibition of BCL-2 anti-apoptotic proteins using small molecule inhibitors has been extensively researched to restore apoptosis and kill cancer cells. A decade of research is rewarded by the recent approval of the BCL-2 selective inhibitor Venetoclax as a second line therapy for chronic lymphocytic leukemia (CLL) patients. Nonetheless, due to the heterogenetic nature of cancers, inhibitors targeting other anti-apoptotic BCL-2 proteins should also be developed not only for different cancer types, but also for the potential resistance generated by MCL-1 up-regulation after BCL-2 inhibition. To date, numerous studies are currently ongoing to discover small molecule inhibitors targeting different anti-apoptotic BCL-2 proteins, primarily MCL-1 and/or BCL-xL, in order to provide insight to dissect these proteins' biological functions, and potentially yield various tool compounds as clinical candidates. Utilizing structure-based drug design strategy, we have designed and synthesized two distinct scaffolds: tetrahydroquinoline (THQ) and salicylate as MCL-1 inhibitors. SAR analysis has been conducted based on their biochemical binding affinities to facilitate the understanding of binding pocket properties. In vitro cell growth inhibition was also evaluated to estimate their potency at cellular level. Another survival mechanism of cancer is through the dysregulation of post-translational modifications, such as aberrant acetylation of histone lysine residues, which abnormally turn on the transcription and expression of oncogenes. Particularly, the bromodomain BRD4 protein is heavily involved in this process as an epigenetic reader to recognize the acetylated lysine residues on histone and regulate the transcription of several oncogenes including c-MYC and BCL-2. Therefore, inhibition of BRD4 may serve as an indirect method to modulate the level of c-MYC and BCL-2 oncoprotein in cancers. Recently, a PLK1 inhibitor BI-2536 was reported as a potent BRD4 inhibitor. The dual inhibition by a single drug molecule might provide the platform for a polypharmacological strategy to treat various cancers. With the guidance of structure-based drug design, we have synthesized and evaluated an SAR library of BI-2536 to dissect their PLK1 and BRD4 inhibition profiles. The fine-tuning modifications of functional groups on BI-2536 furnished both selective BRD4 inhibitors and stronger dual PLK1/BRD4 inhibitors.
    • Roles of the PrrF and PrrH Small RNAs in Iron Homeostasis and Virulence of Pseudomonas aeruginosa

      Reinhart, Alexandria Alana; Oglesby-Sherrouse, Amanda G. (2016)
      Pseudomonas aeruginosa is an opportunistic pathogen that requires iron to cause infection, but also must regulate the uptake of iron to avoid iron toxicity. The iron- responsive PrrF1 and PrrF2 small regulatory RNAs (sRNAs) are part of P. aeruginosa's iron regulatory network and negatively affect the expression of at least 50 genes encoding iron-containing proteins. The genes for the PrrF1 and PrrF2 sRNAs are located in tandem in P. aeruginosa, allowing for the expression of a distinct, heme-responsive sRNA named PrrH that appears to regulate genes involved in heme metabolism. Using a combination of growth, mass spectrometry, and gene expression analysis, we show here that the ΔprrF1,2 mutant, which lacks expression of the PrrF and PrrH sRNAs, is defective for both iron and heme homeostasis. We also present a new system for differentiating PrrF and PrrH function in P. aeruginosa. We delineate the role of these sRNAs in cell physiology and virulence, and identify PrrF as the main regulator of growth, iron homeostasis, and virulence in an acute infection model. Moreover, we show that inoculation with a ΔprrF1,2 deletion mutant protects against future challenge with wild type P. aeruginosa. We also show PrrH does not regulate its current putative targets either in vitro or during acute lung infection, but that this sRNA may impact siderophore production. Although PrrH does not play a role in acute infection, PrrH may play a greater role in a chronic infection, as longitudinal CF isolates maintain the ability to express PrrH throughout disease. Combined, these data demonstrate that the prrF-encoded sRNAs are central regulators of P. aeruginosa iron homeostasis and virulence.
    • Effervescent Aerosols: A Novel Formulation Technology for Solution and Suspension-type Metered Dose Inhalers

      Kelkar, Mukul Sunil; Dalby, Richard N.; 0000-0002-5087-4051 (2016)
      Pressurized metered dose inhalers are complex drug delivery systems which have revolutionized the treatment of asthma and chronic obstructive pulmonary disease since the 1950s. Since the early 1990s, solution and suspension metered dose inhalers have been formulated using HFA-134a and HFA-227 as the propellants of choice, along with other excipients such as ethanol and oleic acid. Performance of an inhaler is partially dependent upon the size of particles it generates, which is partially dictated by intra-canister pressure. In this dissertation, a novel method of formulation of inhalers- the "effervescent aerosol technology" has been introduced. A propellant consisting of HFA-134a containing dissolved carbon dioxide has been used to formulate solution and suspension inhalers. We hypothesized that dissolution of carbon dioxide in HFA-134a will lead to higher degree of aerosol particle size reduction upon actuation, caused due to the process of effervescence i.e. escape of dissolved carbon dioxide from HFA -134a droplet. Since this is a novel technology, the initial part of the dissertation tested the hypothesis in a custom-designed pressure vessel capable of holding and spraying solution inhaler formulations. Particle size analysis was done using Malvern Spraytec®, a laser diffractometry instrument. Formulations prepared using a mixture of HFA-134a and carbon dioxide showed significantly lower particle sizes compared to analogous, pressure-controlled formulations. In the later part of the dissertation, a method to transfer the formulation from the pressure vessel to commercially viable canisters has been described. Further laser diffractometry experiments showed that solution and suspension inhalers prepared using effervescent aerosol technology consistently produce particles with significantly lower particle sizes than HFA-134a-only inhalers. Cascade impaction testing showed that inhalers prepared using a mixture of HFA-134a and carbon dioxide cause significantly lower throat deposition and show improvements in other crucial performance parameters, when compared to HFA-134a-only formulations. Additionally, spray characterization studies such as spray force and plume geometry have also been conducted. This thesis demonstrates that using a combination propellant of liquefied HFA-134a and dissolved CO2 to prepare solution and suspension-type metered dose inhalers is a viable formulation strategy to achieve improved inhaled drug delivery.
    • Effects of Formulation Factors and Pharmaceutical Quality on Oral Drug Absorption

      Vaithianathan, Soundarya; Polli, James E. (2016)
      The overall objective of this dissertation was to study the effects of formulation factors and pharmaceutical quality on oral drug absorption. Aim 1 investigated the impact of large amounts of 14 commonly used excipients on oral absorption of Biopharmaceutics Classification System (BCS) class 3 drugs. FDA and EMA allow biowaivers for BCS class 3 drugs but indicate that test product should be qualitatively the same and quantitatively very similar in composition to the reference product. Capsules containing combination of three excipients in quantities larger than those present in immediate-release (IR) solid oral dosage forms were investigated. Results indicated that 12 out of 14 common excipients were found to not impact BCS class 3 drug absorption in humans, such that these excipients need not be qualitatively the same nor quantitatively very similar to reference, but rather simply be not more than the quantities studied here. Aim 2 addressed the question concerning therapeutic equivalence of brand and generic lamotrigine tablets. A potential contributor to such concerns is pharmaceutical quality. Biopharmaceutics risk of brand and generic lamotrigine 100 mg tablets from several manufacturers was assessed. Results indicated that lamotrigine's favorable biopharmaceutics from a drug substance perspective and favorable quality characteristics from a tablet formulation perspective suggest multisource lamotrigine tablets to exhibit a low biopharmaceutic risk. Aim 3 investigated impact of in vitro dissolution volume on dissolution of IR tablets of three anti-epileptic drugs (AEDs), levetiracetam, lamotrigine, and oxcarbazepine. FDA recently issued two draft guidances that recommend 500 mL dissolution media for BCS class 1 and 3 drugs. Results indicate that reducing dissolution volume from 900 mL to 500 mL was of no apparent significance when at least 3-fold sink conditions prevailed at 500 mL. However, reducing dissolution volume from 900 mL to 500 mL slowed dissolution in the absence of 3-fold sink conditions, per f2. Aim 4 describes the case report of an epileptic patient who observed levetiracetam extended-release (ER) tablet remnants in stool from one generic source but not others. Analysis of tablet remnant indicates that no drug remained in the tablet, even though tablets are mostly composed of drug.
    • Pharmacological Treatment for Serious Mental Illness: Geographic Variation and Association with Preventable Hospitalizations

      HUANG, TING-YING; Simoni-Wastila, Linda (2016)
      Background: The number of older adults with serious mental illness (SMI), including bipolar disorder, schizophrenia, and depressive disorders, is expected to increase. Yet, SMI treatment access and its association with adverse outcomes in this specific population are not well established. This study aims to quantify SMI pharmacological treatment initiation among older adults with SMI, analyze its geographic variation, and examine its association with preventable hospitalizations. Methods: Using 2006-2012 Medicare administrative and claims data, this retrospective cohort study identified fee-for-service beneficiaries newly-diagnosed with SMI. Pharmacological treatment initiation was defined as any prescription fill for medications indicated for the newly-diagnosed SMI in the 12 months after diagnosis, with no use in the 6 months before initiation. The crude and adjusted regional pharmacological treatment incidences were summarized at the hospital referral region level and examined with spatial clustering using local indicators of spatial autocorrelation (LISA). Preventable hospitalizations were measured by the count of hospital or emergency department admissions related to ambulatory care-sensitive conditions (e.g., diabetes, cardiovascular, respiratory disease) during the same follow-up period and compared between SMI treatment pharmacological initiators and nonusers. Generalized linear mixed models with random intercepts were conducted to generate all estimates, adjusting for beneficiary demographics, comorbidities, health services utilization, regional physician supply, and spatial clustering of regional SMI pharmacological treatment incidences. Results: Of the 38,607 beneficiaries aged 65 and older identified with newly-diagnosed SMI in 2008-2012, 64.8% initiated pharmacological treatment after diagnosis. The sample was predominantly female (74.0%) and white (85.1%), with a mean age of 78.5 years. LISA results visualized highly-localized regional pharmacological treatment incidences, with hot spots clustering in the Midwest and upper Pacific West and cold spots in the West South Central and lower New England regions after adjustment. Compared with nonusers, SMI pharmacological treatment initiators showed a 12% reduced risk for preventable hospitalizations (RtR 0.88, 95% CI 0.84-0.93). Conclusions: Findings suggest the majority of older adults with SMI receive pharmacological treatment after diagnosis. Clustering of regional SMI pharmacological treatment incidences implies locally-shared physician practice styles in treating SMI. Timely SMI pharmacological treatment initiation plays an important role in managing risks for preventable adverse outcomes.
    • Topics in Medicare Prescription Drug Enrollment in the Low-Income Subsidy Population

      Hendrick, Franklin B.; Stuart, Bruce C. (2016)
      In Medicare Part D, random assignment and potential yearly reassignment to premium-free stand-alone prescription drug plans (PDPs) is the default plan enrollment option for low-income subsidy (LIS) recipients. Randomization can cause medication access issues, but the impacts on medication use remain unclear because those who choose plans have not been separately examined. Medicare Advantage prescription drug plans (MAPDs) and tailored dual eligible Special Needs Plans (D-SNPs) have financial incentives to improve the medication adherence of Medicare-Medicaid dual eligibles compared to Medicare fee-for-service (FFS), but this relationship has not been assessed. The study used 2006-2009 Medicare administrative data and a customized dataset that differentiated plan election types. In aim 1, 29,784 LIS recipients assigned in 2007 were followed for three years and only 26% became choosers, with half selecting MA plans. PDP choosers appeared sicker and had higher Part D costs than non-choosers. In contrast, MA enrollees had fewer chronic conditions and lower costs than non-choosers. Choosers' plans covered more drugs than non-choosers' plans. In aim 2, medication use and costs were compared among 28,610 statin users who either accepted or opted out of reassignment. Cross-sectional and difference-in-differences (DID) regression models examined changes in statin use and costs. Compared to reassignees, the 7.6% who opted out were less likely to discontinue (-0.8%) and switch statins (-7.0%) and exhibited relative increases over time in brand name use (6.8%) and 30-day fill costs to Medicare ($2.82) and plans ($3.23). In aim 3, drug adherence with statins and angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ACEIs/ARBs) was compared for samples of dual eligibles enrolled in FFS, MAPDs, and D-SNPs over 24 months, including subsamples who switched from FFS to managed care. Analyses included cross-sectional and DID regressions. Drug adherence was slightly higher among managed care dual eligibles when compared to FFS dual eligibles, but a percentage of those switching from FFS experienced disruptions in use. In conclusion, few randomized LIS recipients choose their own plans. Opting out of reassignment has minimal impact on statin adherence and costs. Additional safeguard policies are needed for dual eligibles switching from FFS to Medicare managed care.
    • Contextual Analysis of the Effect of Prostate-Specific Antigen Testing on Prostate Cancer Outcomes among Elderly Men

      Jayasekera, Jinani C.; Onukwugha, Eberechukwu; 0000-0001-9212-7225 (2015)
      Background: Prostate cancer (PCa) is the most common non-cutaneous cancer diagnosed in American men, with a median age of diagnosis of 66 years. There is limited information regarding the impact of pre-diagnosis annual prostate-specific antigen (PSA) testing on PCa outcomes considering the role of contextual characteristics. This study examined geographic variation in the effect of pre-diagnosis annual PSA testing on PCa outcomes, and county-level factors underlying such variation among Medicare-eligible older men. Methods: A retrospective cohort study was designed to analyze men aged 65+ from the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare database. Pre-diagnosis annual PSA testing was stratified as receipt of 0-1 (reference), 2-3 or ≥4 PSA tests 5-years before PCa diagnosis. Composite indices for county-level socioeconomic and health services supply (HSS) characteristics were created using factor analysis. Cluster-specific logistic regression models were used to examine the effect of pre-diagnosis PSA testing on stage at diagnosis and the likelihood of undergoing expectant management (EM) for early-stage PCa. Results: Among 37,760 men, 6% were diagnosed with incident distant PCa and 20% underwent EM within the first two years of PCa diagnosis. In the adjusted analyses, greater intensity of PSA testing was associated with a lower likelihood of incident distant PCa diagnosis (AOR for ≥4 PSA tests: 0.20, 95%CI: 0.17-0.22), and a lower likelihood of undergoing EM (AOR: 0.48, 95%CI: 0.43-0.54). Decreasing HSS characteristics were associated with a higher likelihood of distant PCa diagnosis (AOR: 1.44, 95%CI: 1.08-1.92), and higher likelihood of undergoing EM (AOR: 1.32, 95%CI: 1.09-1.59). While, the effect of pre-diagnosis PSA testing on stage at diagnosis did not vary across counties (p-value=0.21), the effect on undergoing EM varied across counties (p-value<0.01). The fully-adjusted predicted proportions ranged from 3-15% (SD: 7%) for distant PCa diagnosis, and from 12-39% for EM (SD: 4%) across counties. Conclusions: Stage at diagnosis and treatment for early-stage PCa among older Medicare beneficiaries were influenced by individual and county characteristics. Geographic variation in PCa outcomes highlights the variation in health care needs across the U.S. The findings suggest that PCa screening guidelines should be informed by both patient and contextual characteristics.
    • Medicare Disabled Patients with Hepatitis C: Determinants of Quality of Care Receipt, Peg-Interferon Treatment Initiation, and Risk of Metabolic and Vascular Disorders

      Chirikov, Viktor; Shaya, Fadia T.; 0000-0002-9480-0580 (2015)
      Background: Due to years of undetected hepatitis C virus (HCV) infection, the burden of liver and extrahepatic disorders will continue to increase in the US. HCV patients receiving Social Security Disability Benefits represent~70% of HCV patients in Medicare and are an understudied population facing numerous barriers to HCV management. We explored pre-treatment quality of care (QC) patterns, determined the factors associated with differential QC receipt and peg-interferon treatment initiation, and examined the effectiveness of peg-interferon therapy for ?24 weeks at reducing metabolic/vascular risk in Medicare disabled HCV patients. Methods: Medicare claims (2006-2009) linked to the Area Health Resource Files were used. We used a random forest model of conditional inference trees to aggregate QC indicators into high, good, fair, and low QC groupings. Ordinal partial proportional odds regression modelled the receipt of differential QC levels. Modified Poisson regressions, propensity-score weighted for the level of QC received, examined the association between treatment initiation and patient- and county-level characteristics. Poisson regression with weights for treatment selection, discontinuation, and informative censoring due to mortality quantified the effect of peg-interferon treatment on the risk of incident mild, severe, or mild and severe metabolic/vascular events, compared to the untreated. Results: We identified 1,936 patients with continuous enrolment, of whom 10.4% initiated peg-interferon. The five strongest QC metrics predicting treatment included "having received liver biopsy", "HCV genotype testing", "visit to specialist", "confirmation of HCV viremia", and "iron overload testing". While county of residence had no effect on QC receipt, residence in rural counties with high screening capacity was associated with higher prevalence ratio [PR] of treatment initiation (PR=1.42, p=0.09). High QC (PR=5.61, p<0.01) and good QC (PR=2.46, p<0.01) were associated with higher treatment rates. Multiple comorbidities were associated with lower odds of QC receipt (OR=0.76, p=0.05) and treatment initiation (PR=0.27, p<0.01). Over two years of follow-up, there was no difference in metabolic/vascular risk between those treated≥24 weeks (n=43) and untreated (n=879) patients. Conclusion: As barriers to eradicating the HCV infection would likely persist even with novel interferon-free regimens, future research should use our findings to better characterize and optimize treatment in HCV patients with disabilities.
    • CPSF30:A Zinc Finger Protein With An Iron-Sulfur Site

      Aralaguppe Sureshchandra, Kanisha; Michel, Sarah L. J. (2015)
      Zinc finger proteins (ZF's) are a class of proteins that utilize zinc for structural purposes. These metalloregulatory proteins perform a variety of functions ranging from the modulation of gene expression through interactions with DNA and RNA to mediating protein-protein interactions. ZF'-s are characterized by the presence of one or more domains that contain a combination of four cysteines and/or histidine residues that serve as ligands to coordinate zinc. Coordination of zinc to the ligands cause the ZF domain to fold into a three-- dimensional structure and become functional. Based on the number of cysteines and histidine residues in the ZF domains, it is classified as either a classical or a non-classical ZF. Within the non-classical ZF's, there are 14 distinct classes. One of the classes of non-classical ZF's is the Cys3His class. The first protein of this class to be identified was tristetraprolin (TTP), which contains two Cys3His domains (CCCH). Cleavage Polyadenylation Specificity Factor (CPSF30) is another member of this class of protein. The biological role of CPSF30 is to regulate pre-mRNA processing during polyadenylation. CPSF30 contains five repeats of three cysteines and one histidine residues (CCCH) and is annotated as a zinc finger in protein databases. Our lab has overexpressed a construct of CPSF30 that contains the five CCCH domains and utilized a combination of inductively coupled plasma spectroscopy, X-ray absorption spectroscopy and UV-visible spectroscopy to identify the zinc sites and zinc stoichiometry. We have obtained evidence for zinc coordination, as expected, but with stoichiometry ranging from 2-4 zinc ions, rather than the predicted 5. Instead, the fifth site houses an unexpected 2Fe-2S cluster co-factor. To identify where the 2Fe-2S site is located relative to the Zn sites, I have investigated two mutants - one in which the CCCH domain of the first ZF was mutated to all alanine residues and one in which the CCCH domains of the second ZF was mutated to all alanine's. Data regarding the effects of the mutations on metallation and RNA binding is presented.
    • Understanding Curing of Ethylcellulose Film Coating and In Vitro In Vivo Performance of Oral Dosage Forms with Scientific Regulatory Implications on Biowaiver

      Lin, Zhongqiang; Hoag, Stephen W. (2015)
      The aim of this study focus on the extended release formulation on two aspects: the quantification and mechanistic research on pharmaceutical coating curing with a specific focus on how the moisture affect the curing; and in vivo and in vitro release of matrix ER tablets with implications on regulatory biowaiver using marketed products as practical examples. In all cases, it was found that the relative humidity of the environments were more important to reach higher extent of coalescence for EC pseudolatex films and temperature along cannot achieve sufficient polymer coalescence. A quantitative relationship was established that could be used to quantify the extent of coalescence in EC curing to a reasonable accuracy. The NIR spectral data with the tool of chemometrics can enable accurate prediction of physicomechanical properties accurately. Dissolution models demonstrated the release mechanism of EC coated ER multiparticulate was predominately determined by the breaking down of the coating rather than diffusion of drugs through the EC coating layer. Fluoresence anisotropy was found to be useful in the solid system for the first time. By measuring fluorescence anisotropy in the fluorescence labeled EC films can allow real time monitoring of the curing process. To justify biowaiver, it is essential to understand effects of API properties, formulation design, product characteristics, test method and its in vivo relevance. It is therefore concluded that the biowaiver criteria specified in the regulatory guidance should apply only to multiparticulate beaded dosage forms where strengths only differ in the number of beads containing the active moiety.
    • Cost and Management of Fractures in Medicare Beneficiaries with Non-Metastatic Prostate Cancer Treated with Androgen Deprivation Therapy

      Yong, Candice; Onukwugha, Eberechukwu (2015)
      Background: Androgen deprivation therapy (ADT) in prostate cancer (PCa) is associated with increased fracture risk and costs. There is limited information regarding the use of guideline-recommended bone mineral density (BMD) testing and bisphosphonate therapy. This study examined patient-specific (e.g., comorbidity) and non-patient-specific (e.g., physician specialist visits) factors associated with BMD testing, bisphosphonate therapy, fracture risk, and costs. Methods: This retrospective cohort analysis used linked Surveillance, Epidemiology, and End Results & Medicare data on men aged 65+ with non-metastatic PCa and treated with ADT. Cox proportional hazards models examined the association between baseline Charlson Comorbidity Index (CCI) and fracture, accounting for death as a competing risk. Partitioned weighted least squares regression models quantified the 5-year incremental cost of fractures. Multivariable logistic regression models quantified the effect of specialist visits on BMD testing and bisphosphonate use. Results: Of 30,904 men, 6,779 (22%) had a fracture during 5-years of follow-up. Among men aged 66-74 years, the sub-hazard ratio (SHR) (95% CI) for fracture was 1.17 (1.05-1.29) for CCI=1 and 1.69 (1.51-1.90) for CCI=2+ (reference: CCI=0); CCI was not associated with fracture risk among the oldest men aged 85+ years. The mean (95% CI) incremental cost of fractures was $31,800 ($31,709-$31,891), $34,320 ($34,152-$34,488), and $46,678 ($46,534-$46,822) among patients with CCI=0, CCI=1, and CCI=2+, respectively. Following ADT initiation, 17.9% received BMD testing and 9.6% received bisphosphonate. Compared to men who saw a urologist and primary care physician, bisphosphonate receipt was more likely among men with a urologist and medical oncologist involved in their care (AOR=1.89; 95% CI=1.38-2.57), and less likely among men who saw a urologist and radiation oncologist (AOR=0.63; 95% CI=0.42-0.95). There were no statistically significant associations between specialist visits and BMD testing. Conclusions: Patients with greater comorbidity burden had increased fracture risk and higher costs associated with fractures. These patients could benefit from regular monitoring of BMD and bisphosphonate therapy, which occurred in approximately 2 in 10 men. Involving certain types of specialists (e.g., medical oncologists) in the management of men with PCa could be beneficial for bone health management.
    • levo-tetrahydropalmatine (l-THP) and low dose naltrexone (LDN) a novel combination treatment for the prevention of cocaine relapse

      Sushchyk, Sarah Ashley; Wang, Jia Bei; 0000-0001-5523-5876 (2015)
      To date, FDA is yet to approve a medication for the treatment of cocaine dependence or for the prevention of cocaine relapse. One promising potential treatment is l-THP, primarily a modest dopamine antagonist. However, l-THP possesses unwanted sedative side effects, which could be difficult to overcome clinically. The present study aims to develop an improved cocaine relapse treatment, creating an l-THP based combination medication. Our preliminary experiments determined l-THP when co-administered with LDN, decreased the sedative effect and increased the efficacy of l-THP. As a result, the focus of this dissertation was placed on the development of l-THP & LDN as a combination medication for the prevention of cocaine relapse. Specific aims used to accomplish the objective were: 1) determine the efficacy of l-THP & LDN combination for attenuation of cocaine seeking behavior as well as minimization of sedative effect of l-THP and 2) investigate the mechanism of l-THP & LDN through β-endorphin release and POMC expression. The combination of l-THP & LDN attenuated reinstatement of conditioned place preference as well as drug-seeking behavior in the reinstatement of cocaine self-administration. Additionally, the l-THP sedative effect observed at the 3mg/kg and 5mg/kg l-THP doses was ameliorated through co-administration of 0.1mg/kg LDN. Taken together, results of the behavioral studies indicate 3mg/kg l-THP & 0.1mg/kg LDN has the greatest potential as a cocaine relapse prevention treatment. This dosage was used to examine the effect of l-THP & LDN on endogenous β-endorphin release and POMC expression. In animals treated with 3mg/kg l-THP & 0.1mg/kg LDN, we correlated the reduction of drug seeking with an increase of plasma β-endorphin and hypothalamic POMC mRNA expression. This to our knowledge is the first study investigating the underlying mechanism of LDN. The research presented in this dissertation establishes l-THP & LDN as novel treatment for the prevention of cocaine relapse and dependence with great potential for future clinical translation.
    • Molecular Modeling of Macrolide Antibiotic Conformational Sampling and Interactions in the 50S Ribosomal Subunit for the Development of Novel Antibiotics

      Small, Meagan Constance; MacKerell, Alexander D., Jr. (2015)
      Overcoming microbial resistance is a major challenge in the development of antibiotics. Bacteria limit the effectiveness of antibiotics using three major mechanisms: extrusion of the drug via efflux pumps, metabolism to an inactive metabolite, or inhibition of binding by modification of the drug target. The macrolides are an important class of antibiotics that target the ribosome and recent generation macrolides have largely addressed resistance stemming from the first two mechanisms. However, they remain susceptible to resistance due to modification of the ribosome, mainly modification of base A2058 (E. coli numbering throughout) that resides within the heart of the macrolide binding pocket. While crystal structures are available for bacterial 70S ribosomes with macrolides bound, there are none available for A2058-modified ribosomes. Thus, the molecular details underlying A2058 modification-based resistance are unclear. The motivation underlying the present work is to address the need for novel antibiotics, including those addressing A2058 modification-based resistance. To accomplish this, a three-pronged approach has been employed that incorporates both ligand- and structure-based drug design. First, utilizing a ligand-based strategy, the effects of macrolide desmethylation are investigated using molecular dynamics and a pharmacophore-based method known as Conformationally Sampled Pharmacophore (CSP). This will be the subject of Chapter 2. In Chapter 3, the focus shifts to the structure. Molecular dynamics simulations of the 50S subunit are used to understand the impact of A2058 modification on the binding of third generation macrolide antibiotic telithromycin. And, to complete the three-pronged approach, a fragment-based computer- aided drug design method known as Site-Identification by Ligand Competitive Saturation (SILCS) is applied to the ribosome leading to macrolide antibiotics with novel functionality and the potential for enhanced activity against A2058-modified ribosomes. This is the subject of Chapter 4. The methodology underlying all of this work is the use of empirical force field- based simulations, which will be the focus of Chapter 1. As an extension of force fields, Chapter 5 will deal with the optimization of small molecule aldehydes and ketones as Chapter 5 will deal with the optimization of small molecule aldehydes and ketones as well as acyclic sugars toward the development of a comprehensive CHARMM polarizable biomolecular force field based on the classical Drude oscillator.
    • Characterization of Heme Transport in Pseudomonas aeruginosa and the Preferential Pathway for Heme Uptake

      Smith, Aaron Dennison; Wilks, Angela (2015)
      Bacterial pathogens require iron for their survival and virulence and have evolved multiple mechanisms to acquire this scarce micro-nutrient. The Gram-negative opportunistic pathogen Pseudomonas aeruginosa acquires heme as an iron source through the Phu (Pseudomonas heme utilization) and Has (Heme assimilation system) systems. The studies herein detail the initial purification and characterization of the outer membrane (OM) HasR and PhuR receptors. A series of site-directed mutagenesis and spectroscopic studies confirmed HasR, in keeping with previously characterized OM receptors, coordinates heme through the conserved N-terminal plug His-221 and His-624 of the surface exposed FRAP-loop. In contrast PhuR coordinates heme through His-124 and Tyr-519 ligands not previously reported in OM receptors but associated with high affinity heme binding proteins. In vivo studies utilizing a combination of bacterial genetics, isotopic labeling (13C-heme), and qRT-PCR further revealed that both receptors are required for optimal heme uptake. However, whereas deletion of hasR leads to an inability to regulate heme uptake, loss of PhuR results in decreased efficiency in heme uptake, despite a significant up regulation in HasR protein levels. The results are consistent with PhuR being the major heme uptake receptor, while HasR senses and regulates extracellular heme uptake. Thus PhuR and HasR represent non-redundant receptors required for accessing and regulating heme uptake across a wide range of physiological conditions found upon infection. The research presented herein also involved optimization of the ABC-transporter ShuUV along with the soluble periplasmic heme binding ShuT proteins from Shigella dysenteriae, which are involved in the transport of heme across the cytoplasmic membrane and into the cell. By generating and screening a series of expression constructs we were able to obtain a construct that resulted in increased expression levels of ShuUV homodimer. Reconstitution of ShuUV in lipososmes with heme loaded ShuT trapped in the interior of the liposome gave a functional system that could transport heme on activation with ATP. Taken together, the current research lays the foundation for future spectroscopic and structural studies aimed at understanding the molecular mechanisms of membrane bound heme transport proteins.
    • The Impact of Heterogeneity of Treatment Effect on Survival, Cost Effectiveness, and Coverage of Androgen Deprivation Therapy in Metastatic Prostate Cancer

      Aly, Abdalla; Mullins, C. Daniel; 0000-0001-7411-894X (2015)
      Background: Androgen deprivation therapy (ADT) is the standard of care for men with androgen-sensitive Stage IV metastatic (S4M1) prostate cancer. There is a sizable degree of variation in survival (2-4 years) among patients treated with ADT depending on patient factors. It is not clear how this heterogeneity of treatment effect can impact cost effectiveness and payer decision making in oncology. The study was conducted to estimate the survival and cost effectiveness of ADT in men with incident S4M1 prostate cancer across levels of Gleason score and age and to explore how payers use HTE evidence when making coverage decisions in oncology. Methods: Using Surveillance, Epidemiology, and End Results-Medicare datasets, we estimated stratified hazard ratios (HR) and adjusted median survival using inverse probability of treatment weighted Cox proportional hazard models. For cost analyses, we used partitioned inverse probability of uncensored weighted generalized linear models to estimate 3-year ADT costs. Incremental cost effectiveness ratios (ICERs) expressed as $/life years gained (LYG) and bootstrapped confidence intervals were calculated. Results: Among 4,691 S4M1 men, patients treated with ADT had a 52%, 39%, 59%, and 62% relative reduction in the risk of all-cause death in men aged 66-70, 71-75, 76-80, and 80+, respectively compared to untreated men. ADT provided overall survival benefit to men with Gleason 7 (HR: 0.83; 95% confidence interval (CI): 0.63-1.02) and 8-10 (HR: 0.45; 95% CI: 0.41-0.50). The ICER in $/LYG of ADT ranged from $5,806 (95% CI: -4,007-15,929) in 80+ age subgroup to $15,615 (95% CI: -49-37,376) in the 71-75 age subgroup and $24,155 (95% CI: 13,953-34,975) in the Gleason 8-10 subgroup to $39,630 (95% CI: -61-98,505) in the Gleason 7 subgroup. Payers cited multiple factors that may impact the use of HTE evidence into coverage policy, especially the Food and Drug Administration label. Conclusions: ADT provided survival benefit to all subgroups except men with Gleason 2-6. ADT was cost effective in all men with S4M1 prostate cancer at a willingness-to-pay threshold of $50,000/LYG, with the greatest uncertainty in men with Gleason 7. Many factors determined payers' ability to use HTE evidence to inform coverage policy.
    • The Development of levo-Tetrahydropalmatine as a Treatment for Nicotine Addiction

      Faison, Shamia; Wang, Jia Bei; 0000-0002-4355-8624 (2015)
      The negative consequences of nicotine use are well known and documented, however, abstaining from nicotine use and achieving abstinence poses a major challenge for the majority of nicotine users trying to quit. l-Tetrahydropalmatine (l-THP), a compound extracted from the Chinese herb Corydalis, has been used clinically in China for over 40 years as a sedative and analgesic. l-THP has also displayed utility in the treatment of drug addiction, particularly cocaine and heroin addiction. The objective of this dissertation was to investigate if the utility of l-THP could be extended to include treatment of nicotine addiction. As such, the effect of l-THP treatment on abuse-related effects of nicotine was assessed in various behavioral models of nicotine addiction. Once the utility of l-THP was determined, the efficacy of l-THP was tested against varenicline and bupropion, FDA approved treatments for nicotine addiction. To better understand neurochemical changes that occur with l-THP administration, microdialysis experiments were performed where it was found that l-THP interacts with the mesolimbic dopamine system, a prominent pathway of drug addiction. The efficacy of l-THP in the treatment of various models of nicotine addiction and its interaction with the mesolimbic dopamine system make l-THP an attractive compound to study concerning nicotine addiction. Given the long standing safe use of l-THP in China and this new preclinical data, l-THP warrants further study and development for the treatment of nicotine addiction.