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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Candida species variability as seen through clinical covariates and drug susceptibility testing

Hollanbaugh, Jesse Lee 01 May 2010 (has links)
With the recent emergence of candidemia as a significant cause of mortality in our health care system, clinicians must identify methods to minimize the sequelae of infection of this type in patients already burdened with serious underlying conditions. While well established as a major cause of blood stream infection (BSI), candidemia has been shown to have some of the highest rates of inappropriate therapy when compared to infections from all other sources. Rates of inappropriate therapy may be even higher for some of the less common and antifungal resistant non-albicans candidemia. Identifying those patients at risk for the development of these types of infections will help improve clinical outcomes. Antifungal activity is dependent both on species and agent, describing the unique susceptibility patterns between Candida species can help identify the appropriate therapy. We performed a case-case-control study to identify clinical risk factors for the development of Candida glabrata candidemia compared to Candida albicans candidemia and an uninfected control using multivariate and logistic regression analysis. We observed that patients in the C. glabrata cohort were more likely to have gastrointestinal disorders and peripheral vascular disease than patients suffering from C. albicans BSIs. We also determined that when compared to the uninfected control group, patients with C. glabrata BSIs were more likely to have been prior colonized with C. glabrata, undergone dialysis, and have been catheterized with both arterial and urinary catheters. We concluded that patient exposure to unique clinical risk factors may be predictive of the development of future candidemia and may help distinguish between albicans versus non-albicans candidemia. We performed a drug susceptibility study using time-kill methods with the echinocandin antifungal agents on Candida parapsilosis and two newly identified species of Candida, C. orthopsilosis and C. metapsilosis. The echinocandins as a group displayed primarily fungistatic activity against the clinical isolates tested. However, we observed substantial variability in antifungal activity that varied by both the echinocandin used and Candida species analyzed. We concluded that this variability in activity that is both species and drug dependent should be considered when selecting the treatment of candidemia resulting from these non-albicans species.
202

The development and biological evaluation of Octreotide contatining peptides for receptor mediated non-viral gene delivery

Duskey, Jason Thomas 01 January 2013 (has links)
The ability to deliver DNA to target cells creating therapeutic effects remains an important goal in the field of gene therapy. A majority of clinical trials to overcome this issue have utilized viral vectors due to their efficiency at DNA delivery and ability to create high levels of gene expression. However, their inherent toxicity and a several clinical trials leading to patients contracting new diseases from the treatment have greatly hindered the progress of viral gene therapy. Non-viral gene delivery agents have a much better safety profile, but are also much less efficient at delivering DNA, leading to low gene expression. The reason for this low expression is the numerous barriers that must be overcome to achieve gene expression: circulation, tissue specific accumulation, internalization, release of DNA cargo, and nuclear localization. While peptides are currently being improved upon, enhancing binding and the ability to protect DNA, they are still deficient when it comes to tissue specificity. Numerous targeting methods, including the use of lectins, antibodies, aptamers, and peptides, have been designed to deliver molecules to a specific research. Research to incorporate targeting ligands onto non-viral gene delivery vectors is abundant in the literature; however, successful site specific gene delivery has not been achieved. The somatostatin receptor 2 (SSTR2) ligand, octreotide, is a well-researched eight amino acid peptide that has extensive SAR data available. Also, the receptors have been well characterized and octreotide is used clinically in the radioscintigraphy imaging of brain tumors. While well researched, there are unexplored opportunities to utilize octreotide to enhance non-viral gene delivery vectors. The overall scope of this thesis is to develop and synthesize non-viral gene delivery peptides conjugated to octreotide creating receptor mediated targeting of DNA polyplexes to create tissue specific accumulation. Initial experiments indicated that attachment of octreotide to the polycationic peptide WK18 does not inhibit affinity for the SSTR2 receptor. Therefore, peptides were designed and synthesized to attach octreotide onto polyacridine peptide (Acr-Lys)6. Polyplex characteristics were unchanged by the incorporation of octreotide, and exhibited very low genotoxic effects compared to the in vitro gene delivery agent PEI. Competitive binding assays suggested a stoichiometric, ligand, and temperature dependent accumulation of polyplex on SSTR2 expressing cells, but gene expression could not be achieved. The success of (Acr-Lys)6octreotide, led to the synthesis of a di-maleimide-PEG attached to each end by (Acr-Lys4)3Acr-Lys-Cys or Cys-Gly5octreotide in attempts to create distance, and better ligand availability for the receptor, by expressing octreotide away from the polyplex. Testing of this peptide in PEGylated polyplex ad-mixtures verified that separating the DNA binding peptide from octreotide did lead to better inhibition of binding to DAOY cells in a competitive binding study. However, transfection assays with this compound showed background levels of gene expression. Although gene expression was not achieved, the synthetic strategy to create a molecule incorporating a DNA binding peptide, ligand, and PEG to create better ligand presentation to its receptor when incorporated into PEGylated polyplexes is an important step in the design of gene delivery vectors.
203

Metabolic Targets of Gnaphalin Mediated Apoptosis in Colon and Pancreatic Cancer Cell Lines

Gardner, Austin, Ngata, Sam, Howard, La'Travia, Cox, Caden, Palau, Victoria 05 April 2018 (has links)
Colorectal and pancreatic cancer are leading causes of cancer related mortality, suggesting the need for further development of treatment approaches. Gnaphalin, a flavone derived from Gnaphalium gracile H. B. K. which is found in the Andean regions of South America, has shown anti-proliferative properties in solid tumors. Further investigation has shown this compound interferes with signaling conducive to proliferation and cell adhesion, inducing the cell to undergo apoptosis. The primary objective of the study was to look at key regulatory proteins in the cell survival and proliferative pathways to determine Gnaphalin’s mechanism of action. Cytotoxic activity was measured using MTT analysis on the colon cancer cell lines Caco2 and HCT-116, and on the pancreatic cancer cell lines MIA PaCa and Panc28. Apoptosis was determined by the presence of fragmented DNA via TUNEL and cleaved effector caspase 3. Finally, immunoblots were used to determine the mechanism of action using key proteins involved in both the intrinsic and extrinsic apoptotic pathways. Gnaphalin showed the highest activities in colon cancer HCT-116 and pancreatic cancer Panc 28 cells with a half maximal effective concentrations of 25.82±1.0887 and 30.07 ± 1.553 µM respectively. Gnaphalin impediment of cell viability involves the inhibition of phospho-ERK proliferation of the MAPK pathway along with phospho-FAK and c-Met, which are adhesion molecules. Gnaphalin has shown cytotoxic activity towards several colon cancer and pancreatic cancer cell lines by targeting cell proliferation and adhesion, and ultimately causing apoptosis.
204

Dopamine Cell Loss within the Nigrostriatal Pathway Due to Oxidative Stress from Chronic Methylphenidate

Ketchem, Shannon, Ensley, Tucker, Oakes, Hannah, Pond, Brooks B. 05 April 2018 (has links)
Attention deficit hyperactivity disorder (ADHD) is a neurobehavioral disorder that affects 11% of children in the US alo­ne. Methylphenidate (MPH) is the most commonly prescribed drug for the treatment of ADHD. Given the fact that ADHD symptoms persist in up to 50% of patients, many children receive MPH from childhood to early adulthood. Unfortunately, most of the scientific literature focuses on the short-term consequences of MPH, even though individuals are taking MPH for many years. MPH acts by blocking dopamine (DA) transporters and norepinephrine transporters, preventing the reuptake of these catecholamines following release. Previous research has shown that long-term exposure to MPH causes dopaminergic neurons within the nigrostriatal pathway to be more sensitive to the Parkinsonian toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We hypothesize that oxidative stress caused by the spontaneous oxidation of the excess DA in the synaptic cleft is what’s rendering dopaminergic neurons within the nigrostriatal pathway to be more sensitive to MPTP. Adolescent male Swiss-Webster mice were divided into three cohorts and administered either saline (control), 1 mg/kg MPH (normal dose) or 10 mg/kg (abusive dose) via intraperitoneal (IP) injections for 12 weeks. Mice were injected twice daily, Monday through Friday, mimicking a school-week dosing schedule. After 12 weeks, all animals received a drug washout period of 7 days. Then, half of each cohort was treated with MPTP (4 x 20mg/kg, every 2 hours), while the other half was administered 4 injections of sterile saline. Seven days after MPTP or saline treatment, the mice were sacrificed, brains were removed, and the substantia nigra (SN) and striatum (STR) were collected. Oxidative stress related to increased DA levels was determined using the glutathione assay to measure glutathione (GSH) content and near-infrared fluorescence dot blots to measure free and protein-bound ortho-quinones. GSH is an important antioxidant and thus its depletion would be indicative of oxidative stress. Additionally, since DA may be oxidized to a quinone, increases in free and protein-bound ortho-quinones also indicate oxidative stress. Interestingly, we observed a significant decrease in GSH as the dose of MPH increased with both saline and MPTP samples. Furthermore, there was a significant increase in quinones as the dose of MPH increased. In conclusion, it appears that long-term exposure to MPH sensitizes dopaminergic neurons within the nigrostriatal pathway to oxidative stress, rendering them vulnerable to further insults, such as MPTP exposure. As such, these studies provide insight into the risks of long-term psychostimulant exposure.
205

Prevalence and Predictors of Polypharmacy in Adolescents who have Engaged in Sexually Abusive Behaviors

Gilley, Rebecca 01 August 2022 (has links)
Polypharmacy, or the concurrent use of multiple medications, is associated with detrimental outcomes for patients and has gathered increasing attention within the scientific clinical literature. Pediatric populations warrant special consideration for the practice of polypharmacy, as medication effects are more pronounced in youth and adverse effects may have a lasting impact on development. This dissertation study examined psychotropic prescribing practices in a sample of adolescents who have engaged in sexually abusive behaviors, a subset of justice-involved youth who are at risk for polypharmacy. General prescribing trends were examined, and a principle components analysis involving variables associated with risk of polypharmacy was conducted. Results indicated that polypharmacy was common, with many youth being prescribed medications at a young age. Use of risky medications such as antipsychotics was also prevalent, even for individuals without psychosis. Analyses suggested that behavioral issues, trauma and residential instability, and complex psychological concerns were significantly associated with polypharmacy outcomes. Clinical implications of findings are discussed.
206

The Effect of Energy Drinks on Cardiovascular Variables: A Randomized Controlled Trial

Lee, Cynthia 01 January 2019 (has links)
Many studies have investigated the effects of energy drinks on cardiovascular parameters. These studies were typically conducted with high volume (32 ounces) energy drinks and have demonstrated association with QT prolongation and blood pressure elevation after consumption. Currently, there is inconclusive evidence with lower volume energy drinks. This study intends to evaluate the effects of the largest commercially available energy drink can (24 ounces) in the United States on cardiovascular parameters compared with placebo arm. A randomized, double-blinded, placebo-controlled, crossover trial was conducted over 2 separate days with a minimum of 6-day wash out period. Healthy volunteers between the age of 18 and 40 randomly consumed either a 24 oz energy drink or 24 oz placebo control drink on different days. Subjects were required to fast overnight and refrain from products containing caffeine or alcohol 48 hours prior to each study day. ECG, peripheral and central BP, heart rate, and augmentation index were measured at baseline, 1, 2, 3, and 4 hours post-consumption. Primary endpoints were average maximum change of corrected QT (QTc) interval and peripheral systolic blood pressure (pSBP) from baseline. The study enrolled 20 participants with a mean age of 23±5 years. The maximum baseline-adjusted difference of QTc interval was significantly higher in the energy drink arm than the placebo arm (13.68 ± 12.71 vs 4.20 ± 8.80 ms, respectively, p = 0.007). The maximum baseline-adjusted difference of pSBP was significantly higher in the energy drink arm compared to placebo (11.10 ± 5.24 vs 6.08 ± 7.07 mmHg, respectively; p= 0.006). Maximum baseline-adjusted difference of central diastolic BP and systolic and diastolic BP were also statistically significantly higher in the energy drink arm. This study demonstrated that a single, 24-ounce can of an energy drink can significantly prolong the QTc interval and raise pSBP.
207

Kinetic studies of the spasmogenic effects of serotonin and isolates from Byrsonima crassifolia leaves on rat fundus

Béjar, Ezra 01 January 1991 (has links)
Leaf and bark extracts of a Mexican medicinal plant, Byrsonima crassifolia (Malpighiaceae), exhibited spasmogenic effects on isolated rat fundus and biphasic effects on jejunum and ileum. Preliminary evaluations using rat fundus in Krebs solution indicated that the activity of a 2% acetic acid extract of eaves (HOAcE) could be split into two types: (i) high-efficacy, low-potency, n-butanol-extracted, pargyline- and 1-(1-naphtylpiperazine) (1-NP)-sensitive, atropine-insensitive activity, and (ii) low-efficacy, high-potency, ethyl acetate-extracted, pargyline-insensitive, atropine- and 1-NP-sensitive activity. HOAcE lacked muscarinic and nicotinic effects on rat jejunum and frog rectus abdominis. Serotonin (5-HT) and HOAcE curves in fundus were parallel and 5-HT potency was 6,037 times that of HOAcE (95% confidence limits: 4,624-7,852). The pD2 (affinity constant) for 5-HT was 7.96 (7.92-8.00) with pargyline added to the medium. 5-HT receptor-interaction kinetics using cholinergics and 5-HT agonists and antagonists was carried out. 1-NP competitively antagonized 5-HT. The 5-HT, antagonist s-(-)propranolol did not significantly antagonize 5-HT. The 5-HT2 blocker ketanserin noncompetitively antagonized 5-HT and α-Me-5-HT (pD'2 = 5.6 and 6.7, respectively). The 5-HT3 antagonist MDL-72222 inactivated only a small proportion of receptors (pD'2 = 6.46). Atropine did not significantly modify the curve of 5-HT while fluoxetine noncompetitively antagonized 5-HT (pD'2 = 5.8). 5-HT and α-Me-5-HT curves were biphasic indicating two receptor interactions (high and low affinity). High-affinity pD2 values for six different 5-HT agonists and 1-NP on rat fundus correlate well with reported rat brain (radioligand binding) pKd values at the 5-HT1C receptor (r = 0.94). Large scale extraction and fractionation of a methanol extract of leaves yielded two peaks of activity (Peak 1, lipophilic; Peak 2, polar). Peak 1 contained Compounds 1 to 7 (C1-C7); Peak 2 included C8-C15. Compound 1, C2, C3, C4, C10 and C11 were inactive while C8, C12 and C13 showed equivocal effects. Compound 5, C6, C7, C9, C14, C15, quercetin and gallic acid were active. Potencies were: C5 > C6 > C7 = quercetin > C9 > gallic acid. Efficacy (IA) was: C15 ≥ C14 > gallic acid > C9 > C5 > C7 > quercetin > C6. Compound 9 and its aglycone quercetin were partial agonists (C9 IA = 70%, pD2 = 6.35; quercetin IA = 60%, pD2 = 6.58). Compound 9 noncompetitively antagonized 5-HT (pD'2 = 6.10), while quercetin did not. Compound 14 and C15, the most active compounds, had similar response curves but these curves were not parallel to 5-HT. Spasmogenic ED50 values for C14 = 0.76 (0.38-1.54) μg/mL and C15 = 0.76 (0.41-1.42) μg/mL. Gram for gram 5-HT was 181 x C14 and 182 x C15.
208

A comparison of the fluidized bed drying technique with conventional methods of drying tablet granulations

Mills, Kit Michael 01 January 1969 (has links)
Drying procedures, like other important unit operations in pharmacy, have received little attention in pharmaceutical literature. Within recent years, however, growing interest in these pharmaceutical engineering areas has become apparent. Fluidization operations, although relatively unexplored in pharmacy, have been firmly established on a broad scale in other industries. Fluidization may be defined as the suspension and agitation of a bed of particulate solids by a vertically rising stream of gas. Each suspended particle is surrounded by the gas. This relative velocity of the gas and solid particles is high, although the gas velocity itself is relatively low. Heat is transferred by by a combination of conduction and convection and by the movement of the solid particles (1). Fluidized bed drying of moist phosphate rock, coal, and many other materials has been discussed in technical literature (1, 2). However, relatively few reports have appeared on the applications of fluidized beds to materials of pharmaceutical interest. These technical studies show that uniform bed temperatures with high heat and mass transfer rates are obtainable in fluidization system. Product temperatures are controllable over narrow limits within the fluidized bed. These reported advantages would appear to have particular importance in processing pharmaceuticals. It is difficult to understand, therefore, why only a few studies on fluidized bed drying have appeared in pharmaceutical literature. Apparently no comprehensive studies dealing with finished tablets, compressed from granulations dried by the fluidization technique, have appeared in pharmaceutical literature. Accordingly, it would seem appropriate that more studies be conducted, in pharmaceutical fields, concerning drying procedures, especially the fluidization process. The present project will consist of conducting a series of tests on identical granule formulations dried by the conventional air drying and oven drying processes as well as the fluidized bed drying technique. The present work will also include the performance of tests on specific physical properties of tablets compressed from the test granulations.
209

Effects of the medication reminder record with counseling and the daily medication package on drug compliance by ambulatory psychiatric patients

Gazzar, Albert T. 01 January 1978 (has links)
Drug default is the failure of a patient to comply fully with medication regimens and is major unsolved problem confronting health care providers oday. Drug default is also known as medication noncompliance. Very few studies have been reported comparing the effects of counseling and the unit dose packaging upon compliance. Further, no studies have been reported on the effects of counseling and unit dose packaging upon compliance in ambulatory psychiatric patients. The present investigation was undertaken to (i) evaluate the effectiveness of the Medication Reminder Record, a type of patient calender sheet, with counseling as a means of improving compliance with medication regimens in an ambulatory psychiatric patient population; and (ii) contrast the effects of the Daily Medication Package with counseling and Medication Reminder Records for ambulatory psychiatric patients.
210

Characterization of the physical properties and the bioavailability of phenobarbital tablets, USP, 100 mg

Sylvestri, Mario F. 01 January 1976 (has links)
The Food, Drug, and Cosmetic Act of 1938 required a producer of a new drug to substantiate the safety of the drug product when used as recommended; however, the introduction of the Kefauver-Harris Amendments of 1962 considerably strengthened this act. These amendments intensified the controls on quality, labeling, and safety, while adding a new requirement that all NDA's should be able to present substantial evidence of the effectiveness of the drug product for its indicated use of uses (4). The procedure used to determine the efficacy of a drug included identification of the product, copies of the labeling, and a bibliography of publications substantiating the claims made for the drug. The manufacturers were also requested to submit any unpublished information to further substantiate the claims made for the drug product (5,6). Bioavailability is a complex problem due to the many variables associated with the development of drug dosage form design. The bioavailability of a drug product can be influenced by pharmaceutical formulation factors as well as by the physiological factors of the patient taking that drug product. Compressed tablets are the mostly widely used of all the dosage forms, and they present the most problems in regard to the bioavailability of the active component. This is especially true for those compressed tablets that contain drugs with a low solubility, a low rate of solution, drugs which exhibit poor absorption characteristics, drugs which are unstable in the gastrointestinal environment or drugs that are used in large dosage (25). The significance of a bioavailability study is established when a correlation is demonstrated between the blood levels achieved using a drug already shown to be clinically effective and the drug product being tested (34). This type of relationship tends to indicate that the drug product being tested would be therapeutically equivalent to the reference drug product (35). Bioavailability data is necessary for the establishment of therapeutic equivalency among drug products. Consequently, bioavailability data is necessary for the establishment of therapeutic equivalency among drug products; particularly for those drug products most often prescribed. Phenobarbital tablets have been listed among the top 5 generic products, by new prescription volume, for the last 4 years. In addition, phenobarbital tablets have been the leading drug product amon the top 20 generic products by refill prescription volume over the last 4 years. Of the top 20 generic products by new and refill prescription volume, phenobarbital products have ranked among the top 3 for the past 4 years. Furthermore, phenobarbital tablets have been listed among the top 4 drug products in a list of the average retail new prescription prices for the top 20 generic products in the last 4 years (36). From a physiochemical basis, the bioavailability of phenobarbital tablets has been suspect. The incomplete data available on phenobarbital tablets indicated the necessity for determining the physical properties and the bioavailability of these products. Therefore, Phenobarbital Tablets, USP, 100 mg, were obtained from 7 manufactures to characterized the physical properties of tablet weight, hardness, disintegration time , and dissolution rate; to determine the bioequivalency, bioavailability studies were conducted employing 5 normal, healthy human adult male subjects.

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