Simvastatin is a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor that is used for the treatment of hyperlipidemia. Simvastatin has recently been studied for its potential use in cancer therapy. In-vitro studies have shown that simvastatin displays anticancer activity, but at concentrations unlikely to be achieved in patients being receiving typical antihyperlipidemic treatment doses. Thus, several clinical trials were conducted to study the tolerability of high dose statins in cancer patients. The maximum tolerated dose of simvastatin was determined to be 15 mg/kg/day, 25-fold higher than a typical dose. However, it is not known if simvastatin plasma concentrations can reach those found to be effective in-vitro. In this context, we initiated a clinical study to determine the pharmacokinetics of high dose simvastatin in patients with chronic lymphocytic leukemia. For this purpose, an LC-MS/MS method was developed and validated for the quantitation of simvastatin and its acid form in plasma and peripheral blood mononuclear cells obtained from CLL patients. Results show that simvastatin concentrations were dose proportional relative to the antihyperlipidemic doses, but lower than those required for in-vitro cytotoxicity against cancer cells. These findings demonstrate that the in-vitro effective concentrations of simvastatin are not achievable clinically, which might explain the limited effectiveness of high dose simvastatin in this study and in previous clinical trials. In view of these data, the use of simvastatin as a sole therapy in cancer treatment was not encouraging and led us to examine the use in combination with other anticancer drugs. After screening several chemotherapeutic agents in combination with simvastatin, we showed that tipifarnib (a farnesyltransferase inhibitor) interacts synergistically in several leukemia cell lines. Mechanistically we showed that simvastatin augments the cytotoxicity of tipifarnib by disrupting the localization of RAS in the cell membrane and by subsequent deactivation of the ERK pathway. Consistent with this observation, drug treatment led to the induction of apoptosis through the caspase cascade activation and the cleaved PARP upregulation. Notably, this synergistic effect was observed at clinically achievable concentrations of simvastatin and tipifarnib. Thus, the effectiveness of this combination should be explored further in future clinical studies.

The majority of pharmacologically active chemotherapeutics are poorly water soluble. Solubilization enhancement by the utilization of organic solvents often leads to adverse side effects. Nanoparticle-based cancer therapy, which is passively targeted to the tumor tissue via the enhanced permeation and retention effect, has been vastly developed in recent years. Nanocrystals, which exist as crystalline and carry nearly 100% drug loading, has been explored for delivering antineoplastic agents. Additionally, the hybrid nanocrystal concept offers a novel and simple way to integrate imaging agents into the drug crystals, enabling the achievement of theranostics. The overall objective of this dissertation is to formulate both pure and hybrid nanocrystals, evaluate their performance in vitro and in vivo, and investigate the extent of tissue distribution and tumor accumulation in a murine model. Pure and hybrid nanocrystals of several model drugs, including paclitaxel (PTX), camptothecin, and ZSTK474, were precipitated by the antisolvent method in the absence of stabilizer, and their size was further minimized by homogenization. The nanocrystals of PTX, which is the focus of the study, had particle size of approximately 200 nm and close-to-neutral surface charge. Depending on the cell type, PTX nanocrystals exerted different level of cytotoxicity. In human colon and breast cancer xenograft models, nanocrystals yielded similar efficacy as the conventional formulation, Taxol, at a dose of 20 mg/kg, yet induced a reduced toxicity. Biodistribution study revealed that 3H-PTX nanocrystals were sequestered rapidly by the macrophages upon intravenous injection. Yet, apparent toxicity was not observed even after four weekly injections. The sequestered nanocrystals were postulated to be released slowly into the blood circulation and reached the tumor. Tritium-labeled-taxol, in contrast, was distributed extensively to all the major organs, inducing systemic toxicity as observed in significant body weight loss. The biodistribution results obtained from radioactive analysis and whole-body optical imaging was compared. To some degree, the correlation was present, but divergence in the quantitative result, due to nanocrystal integrity and limitations associated with the optical modality, existed. Despite their promising properties, nanocrystal suspensions must be securely stabilized by stealth polymers in order to minimize opsonization, extend blood-circulation time, and efficiently target the tumor.

Empiric antimicrobial therapy often consists of the combination of Gram-positive coverage with vancomycin (VAN) and Gram-negative coverage, specifically an anti-pseudomonal beta-lactam, such as piperacillin-tazobactam (PTZ). Nephrotoxicity is commonly associated with VAN therapy; however, recent reports demonstrate increasing nephrotoxicity rates among patients treated with the combination of VAN and PTZ. This study evaluated the effect of the VAN/PTZ combination on acute kidney injury (AKI), as defined by the RIFLE criteria, compared to VAN and PTZ monotherapies. Overall, 11,650 patients were analyzed, with 1,647 (14.1%) AKI cases occurring. AKI was significantly more frequent in the VAN/PTZ group (21%) compared to either monotherapy group (VAN 8.3%, PTZ 7.8%, p<0.001 for both). Combination therapy was independently associated with higher AKI odds compared to monotherapy with either agent (aOR=2.03; 95% CI 1.74-2.39; aOR=2.31; 95% CI 1.97-2.71, for VAN and PTZ, respectively). Receipt of concomitant nephrotoxic drugs were independently associated with increased AKI rates, as were increased duration of therapy, length of hospital stay, increasing severity of illness, and increasing baseline renal function. VAN combined with PTZ was associated with twice the odds of AKI development compared to either agent as monotherapy. This demonstrates the need for judicious use of combination empiric therapy.

Background: Dietary supplements (DS) use has increased in the U.S. in the past 20 years. More than half of the U.S. population reported using DS. There are few studies to our knowledge that have assessed DS use specifically for older adults. In this study we purposed to evaluate the trend of using DS among older adults and to test the association between using DS and several demographics, socioeconomics and health characteristics. The second objective was to evaluate the reasons behind using DS among older adults using a nationally representative database. Methods: This is a cross sectional study using the most recent National Health and Nutrition Examination Survey (NHANES) database 2009-2012. It is a nationally representative sample of noninstitutionalized adults in the U.S. Frequency and weighted percentage (standard error) were reported for dichotomous variables. Multiple logistic regressions model analyses were used to evaluate the predictors of DS use after testing model assumptions, multicollinearity, and outliers. P values 0.05 were considered significant. All the statistical analyses were conducted using SAS software version 9.4. Results: Out of 2625 older adult participants (65 years and older) 70.5% of them reported using DS in the past 30 days. Female, non-hispanic white, obese, overweight and excellent and very good self-reported health status participants were more likely to use DS. Multivitamin-multiminerals (MVMM), calcium and vitamin D were the most commonly reported supplements among older adults. 71% of oldest old (80≥ years) reported taking DS and prescription medication in the past 30 days concomitantly and 73% of polypharmacy users reported using DS. To stay healthy, to improve overall health and for bone health were the most commonly reported reasons behind using DS. Conclusion: majority of older adult participants reported using DS in the past 30 days. Health care professionals need to evaluate the dietary supplement information from older adults in order to improve health care.

Dystrophia myotonica (DM1), one of the most common forms of muscular dystrophy, is caused by a repeated trinucleotide expansion in the DMPK gene. This mutation results in the accumulation of toxic cellular RNA transcripts. Spliceosome-mediated RNA trans-splicing (SMaRT) technology is a form of gene therapy that possesses the potential to correct these toxic RNA transcripts and thus cure the disease. Despite its promise, prior research applications of SMaRT technology to DM1 have been hampered by poor efficiency and have not been validated in a relevant model of the disease. In order to improve the efficiency of trans-splicing, this study examined the use of novel SMaRT molecules containing altered binding domains. These SMaRT molecules were tested in a clinically relevant cell model of DM1 and their corrective ability compared with that of a standard SMaRT molecule. The results were quantified by RT-PCR. The outcome of this study indicated the need to utilize more specific methods for measuring efficiency and for understanding the specific interactions of SMaRT molecules with target transcripts.

As HIV is now primarily a chronic condition, treatment is given life-long with changes as necessitated by alterations in tolerability and efficacy. Thus, personalized medicine may be useful in the prevention of unnecessary drug exposure and avoidable side effects. Three of the four currently available HIV integrase strand transfer inhibitors (INSTIs), raltegravir, elvitegravir, and dolutegravir, are widely utilized antiretrovirals in the USA and exhibit variations in outcomes among subjects. To interrogate differences among subjects receiving these drugs, we investigated the association of several single nucleotide polymorphisms (SNPs) with drug exposure, clinical outcomes, and subject-reported adverse events. HIV+ adults (≥18 years old) receiving an INSTI regimen were recruited (n=88). Subject genotypes were evaluated using an iPLEX PGx Panel. Genetic variations within our population, underwent multiple regression with covariates [age, sex, BMI, regimen duration, and baseline variables (as required) along with specific regimen in the comprehensive group] to detect significant (p=0.028) between abnormal dream occurrence and specific INSTI regimen with the raltegravir grouping presenting a higher frequency. This exploratory study also discovered several SNP-outcome associations when using INSTIs. Although these SNPs were found to have a role in predicting segments of adverse effect profiles, the clinical significance of these findings remains to be determined. Larger studies will be needed to confirm these exploratory findings with functional studies to understand pathogeneses. In conclusion, the associations found in this study strengthen the need for further assessment, within the HIV+ population, of factors contributing to unfavorable subject outcomes.

This cross-sectional study used a weighted sample of ED visits contained in the 2010-2015 years of the National Hospital Ambulatory Care Survey-Emergency Department (NHAMCS-ED) dataset. The purpose of this study was to: 1) identify differences in predisposing, enabling, and need characteristics, and ED use and medication prescribing characteristics between homeless and nonhomeless ED users; 2) assess the association between housing status and medication prescribing at ED discharge, and identify variables contributing to the disparity in medication prescribing between homeless and nonhomeless ED users; and 3) assess the predisposing, enabling, need, and ED use characteristics that predict medication prescribing at ED discharge among homeless ED users. This research is guided by the Andersen-Gelberg Behavioral Model for Vulnerable Populations. There were a total of 502,614,359 visits to EDs located within a MSA made by homeless and nonhomeless adults 18 years of age and older. About 0.9% of these visits were made by homeless individuals. Age, mental health diagnosis, substance use diagnosis, primary payer, and patient-reported pain differed significantly between homeless and nonhomeless ED users. A significantly greater proportion of homeless ED users arrived to the ED via ambulance, and was seen in the last 72 hours. Homeless ED users tended to have longer ED visits, and ED disposition differed significantly between homeless and nonhomeless ED users. A significantly smaller proportion of homeless ED users were prescribed a medication at ED discharge, and an opioid medication at ED discharge. There was no difference in the likelihood of medication prescribing at ED discharge between homeless and nonhomeless ED users after controlling for predisposing, enabling, need, and ED use characteristics. ED diagnosis was the greatest contributor to the disparity in medication prescribing at ED discharge between homeless and nonhomeless ED users. Among homeless ED users, visits covered by Medicare and other payers were significantly more likely to result in medication prescribing at ED discharge compared to nonhomeless ED users covered by private insurance. Homeless ED users with no substance use condition diagnosis were significantly more likely to be prescribed a medication at ED discharge compared to those with a substance use condition diagnosis.

Human immunodeficiency (HIV) infection can result in neurocognitive deficits in about one-half of infected individuals. Despite excellent systemic effectiveness, restricted antiretroviral penetration across the blood-brain barrier (BBB) is a major limitation in fighting HIV infection within the central nervous system (CNS). Drug abuse exacerbates cognitive impairment and pathologic CNS changes in HIV-infected individuals. This work investigates the effects of the HIV-1 protein, Tat, and drugs of abuse on factors affecting drug penetration into the brain. Firstly, an in vitro model of the blood-brain barrier was built to study effects of HIV-1 Tat and methamphetamine (Meth) on integrity and function of the BBB, in turn how HIV-1 Tat and meth will affect antiretroviral penetration into the brain. We found that co-exposure HIV-1 Tat and Meth results in inhibition or impairment of P-glycoprotein activity at the BBB. Also, simultaneous inhibition of P-glycoprotein (P-gp) and Multidrug Resistant Protein -1 (MRP-1), by verapamil and MK-571 causes an increase in accumulation of atazanavir inside the primary human brain endothelial cells. Secondly, we developed and validated the method for simultaneous determination of tenofovir, emtricitabine, and dolutegravir in cell extracts of CNS cells. This method was used to study how HIV-1 Tat and/or morphine affects antiretroviral penetration in CNS cells like human brain microvascular endothelial cells, human astrocytes, human microglia, and human pericytes. We found that in untreated cells, accumulation of antiretroviral drugs was higher in hCMEC/D3 cells compared to other CNS cell types. Also, HIV-1 Tat and/or morphine had no significant effect on antiretroviral penetration amongst these cell types. Overall, the rank order of intracellular accumulation observed in treated and untreated cells was dolutegravir > emtricitabine > tenofovir.

Background: Antibiotic overuse/misuse has been documented in several reports to increase the risk of Clostridioides difficile (C.diff) infection and antibiotic resistance. The older adult population is more prone to use antibiotic medications than any other age group due to decreased immune function, use of urinary catheters, ventilation during hospitalization and other factors. Antibiotic resistance and C.diff are major public health problems. However, studies examining the trends of antibiotic use and the association between the antibiotic use and negative health outcomes among older adults in the outpatient and emergency department settings are limited. Objectives: The main objectives of this dissertation were to: 1) calculate the national antibiotic trends among community-dwelling older adults in the United State; 2) evaluate the antibiotic trends and antibiotic appropriateness among older adult patients visiting the geriatrics clinic and adult internal ambulatory care clinic at VCU Health; and 3) examine the antibiotic trends and antibiotic appropriateness among older adult patients and middle-aged patients visiting the emergency department at VCU Health. Methods: For the first objective, data were obtained from Medical Expenditure Panel survey (MEPS) a nationally representative dataset (2011-2015). Descriptive analyses were conducted and multiple logistic regression was performed to assess the association between the antibiotic use and demographic and sociodemographic characteristics. In the second objective, data were obtained from VCU Health outpatient clinics (geriatrics, and Internal medicine ambulatory care clinic only). Descriptive statistics were calculated and multiple logistic regression was performed to assess the association between antibiotic appropriateness and type of clinics and other demographic characteristics. In the third objective, the emergency department electronic medical records at VCU were used. Trend analysis was performed across the dissertation studies using the Cochran–Armitage test. All variables were considered statistically significant at an α level of 0.05. All the statistical analyses were conducted using the Statistical Analysis Software Version 9.4 (SAS v.9.4), (SAS Institute Inc, Cary, NC). Results: There were 105,762,134 prescriptions dispensed to older adults in the outpatient setting in the US from 2011 to 2015. Antibiotic prescriptions were more common among women (18%) compared to men (12%). White participants received more antibiotics (27%) than African Americans (1.77%) and others (1.4%). Among the 3,515 patients who visited either Geriatrics or Internal Medicine ambulatory clinic at VCU Health from 2012-2017, 1,534 antibiotics were prescribed. Potentially inappropriate antibiotic prescriptions were similar between the two clinics (30% in Geriatrics clinic and 28% in Internal Medicine ambulatory clinic) with p-value of 0.08. In addition, 6,343 middle-aged or older adult patients were dispensed and prescribed an antibiotic in the ED at VCU Health from (2012 to 2017). Eighteen percent of the antibiotic prescriptions received by middle age group were considered potentially inappropriate, compared to 9% among the older adult patient (p < 0.0001). Conclusions: The rate of antibiotic use overall remains unchanged despite the national and international efforts to reduce antibiotic prescriptions and eventually to reduce antibiotic resistance. The changes in the patterns of use in some of the antibiotic categories appear to be driven more by the safety concerns rather than reducing overall use. Future research is needed to strengthen antibiotic stewardship programs for older adults in outpatient settings.

The small- and intermediate-conductance Ca2+ activated K + (SK/IK) channels play a fundamental role in the regulation of neurons in the central nervous system. In animal models, SK/IK channel positive modulators have been shown to be effective in reducing the symptoms of neurological diseases such as ataxia. Ataxia is a lethal neurological rare disease characterized by lack of balance and incoordination of muscle movements, often as a result of cerebellar or spinocerebellar neurodegeneration. SK/IK channel modulators have been developed over the past few decades. Currently available modulators are often weak in potency. Lack of knowledge about the binding site for the compounds is the main reason hindering the development of more potent and effective therapeutics targeting SK channels. Dr. Zhang and his colleagues recently discovered the binding pocket for these positive modulators of SK/IK channels. This pocket is located at the interface between the channel and calmodulin. Dr. Zhang and his colleagues performed screening of a large number of compounds in silico, to find those fitting into the binding pocket. I performed electrophysiological recordings to evaluate the efficacy and the potency of these modulators on SK2 channels. We discovered a correlation between the total binding energy values calculated from the structures and the potencies determined from electrophysiological recording.