FEXOFENADINE AND ORGANIC ANION TRANSPORTING POLYPEPTIDES (OATPs): TRANSPORT AND DRUG-DRUG INTERACTIONS

Transporters play a major role in the absorption and disposition of fexofenadine, suggesting this drug could be used as a probe of transporter activity. When fexofenadine was administered in combination with four drugs (buspirone, caffeine, dextromethorphan and losartan) used to probe cytochrome P450 (CYP) activities, a significant decrease in fexofenadine AUC was observed without a change in elimination. Based on this observation, I hypothesized a fexofenadine-probe drug interaction was occurring during oral absorption, and that this interaction was occurring at an enterocyte-expressed OATP. This interaction was reproduced and studied using in vitro model systems. In Specific Aim 1, a specific LC-MS/MS method was developed and validated for the quantification of fexofenadine and the other four probe drugs for use in the remaining specific aims. In Specific Aim 2, the interaction between fexofenadine and four enterocyte- and hepatocyte-expressed OATPs was characterized, and OATP1A2 was identified as the most effective transporter of fexofenadine, with a Km of 35 μM. Because fexofenadine was efficiently transported by OATP1A2, the four CYP probe drugs were tested as inhibitors of OATP1A2-mediated fexofenadine transport in Specific Aim 3. Buspirone, losartan, and dextromethorphan each inhibited OATP1A2-mediated fexofenadine transport in a concentration dependent manner. This inhibition could explain the decrease in fexofenadine oral bioavailability seen in the clinical study we had previously conducted. The replication of the fexofenadine-probe drug interaction in this model system supports the conclusion that OATP1A2 is the major uptake transporter for fexofenadine absorption in the enterocyte, and suggests that fexofenadine may be an effective probe drug for this transporter. In Specific Aim 4, I further characterized the fexofenadine-probe drug interactions using the three known OATP1A2 polymorphisms: Ile13Thr, Arg168Cys, and Glu172Asp. While the mutants functioned as expected with regard to fexofenadine transport, the presence of the mutation did not alter the observed drug-drug interactions seen previously with OATP1A2 and the CYP probes. Taking these data into account, it appears the fexofenadine-drug interaction seen previously is not affected by single nucleotide polymorphisms. This work demonstrates that OATP1A2 is capable of transporting fexofenadine and that several CYP probe drugs inhibit its transport by OATP1A2. This latter observation limits the utility of fexofenadine to be used as a single probe, rather than as part of a probe drug cocktail

In silico and in vitro drug screening identifies new therapeutic approaches for Ewing sarcoma.

The long-term overall survival of Ewing sarcoma (EWS) patients remains poor; less than 30% of patients with metastatic or recurrent disease survive despite aggressive combinations of chemotherapy, radiation and surgery. To identify new therapeutic options, we employed a multi-pronged approach using in silico predictions of drug activity via an integrated bioinformatics approach in parallel with an in vitro screen of FDA-approved drugs. Twenty-seven drugs and forty-six drugs were identified, respectively, to have anti-proliferative effects for EWS, including several classes of drugs in both screening approaches. Among these drugs, 30 were extensively validated as mono-therapeutic agents and 9 in 14 various combinations in vitro. Two drugs, auranofin, a thioredoxin reductase inhibitor, and ganetespib, an HSP90 inhibitor, were predicted to have anti-cancer activities in silico and were confirmed active across a panel of genetically diverse EWS cells. When given in combination, the survival rate in vivo was superior compared to auranofin or ganetespib alone. Importantly, extensive formulations, dose tolerance, and pharmacokinetics studies demonstrated that auranofin requires alternative delivery routes to achieve therapeutically effective levels of the gold compound. These combined screening approaches provide a rapid means to identify new treatment options for patients with a rare and often-fatal disease

Surgical vein graft preparation promotes cellular dysfunction, oxidative stress, and intimal hyperplasia in human saphenous vein

IntroductionHuman saphenous vein (HSV) is the most widely used bypass conduit for peripheral and coronary vascular reconstructions. However, outcomes are limited by a high rate of intimal hyperplasia (IH). HSV undergoes a series of ex vivo surgical manipulations prior to implantation, including hydrostatic distension, marking, and warm ischemia in solution. We investigated the impact of surgical preparation on HSV cellular function and development of IH in organ culture. We hypothesized that oxidative stress is a mediator of HSV dysfunction.MethodsHSV was collected from patients undergoing vascular bypass before and after surgical preparation. Smooth muscle and endothelial function were measured using a muscle bath. Endothelial preservation was assessed with immunohistochemical staining. An organ culture model was used to investigate the influence of surgical preparation injury on the development of IH. Superoxide levels were measured using a high-performance liquid chromatography-based assay. The influence of oxidative stress on HSV physiologic responses was investigated by exposing HSV to hydrogen peroxide (H2O2).ResultsSurgical vein graft preparation resulted in smooth muscle and endothelial dysfunction, endothelial denudation, diminished endothelial nitric oxide synthase staining, development of increased IH, and increased levels of reactive oxygen species. Experimental induction of oxidative stress in unmanipulated HSV by treatment with H2O2 promoted endothelial dysfunction. Duration of storage time in solution did not contribute to smooth muscle or endothelial dysfunction.ConclusionsSurgical vein graft preparation causes dysfunction of the smooth muscle and endothelium, endothelial denudation, reduced endothelial nitric oxide synthase expression, and promotes IH in organ culture. Moreover, increased levels of reactive oxygen species are produced and may promote further vein graft dysfunction. These results argue for less injurious means of preparing HSV prior to autologous transplantation into the arterial circulation.Clinical RelevanceApproximately 1,000,000 aortocoronary and peripheral vascular reconstructions are performed annually using human saphenous vein grafts. However, outcomes from this procedure are limited by high rates of graft failure. The leading cause of vein graft failure is intimal hyperplasia. A multifactorial process, intimal hyperplasia is thought to arise at least in part due to vein graft injury. Significant trauma occurs to the graft during surgical harvest and subsequent preparation, significantly impairing cellular function and increasing oxidative stress. Efforts to reduce early vein graft injury during harvest and preparation may have the potential to reduce subsequent vein graft failure in patients

Comparison of Body Composition Measurements using a New Caliper, Two Established Calipers, Hydrostatic Weighing, and BodPod

Purposes: (1) To compare the Lafayette Instruments (LI) skinfold caliper to the Lange (L) and Harpenden (H) calipers using a diverse subject population. (2) To determine the validity of the LI caliper in a subset of subjects by comparing body compositions from skinfold thicknesses to those measured by hydrostatic weighing (HW) and air displacement plethysmography (ADP). (3) To compare measurements obtained by experienced (EX) and inexperienced (IX) technicians using all three calipers. Methods: Skinfold measurements were performed by both EX and IX technicians using three different calipers on 21 younger (21.2 ± 1.5 yrs) and 20 older (59.2 ± 4 yrs) subjects. Body compositions were calculated using the Jackson-Pollock seven-site and three-site formulas. HW and ADP tests were performed on a subset of subjects (10 younger, 10 older). Results: No significant differences existed between LI and L or H when measurements were made by EX. Further, the LI-EX measurements were highly correlated to both H-EX and L-EX. No significant differences existed in the subgroup between LI-EX and HW or ADP. Skinfold determinations made by EX and IX were similar. Conclusions: Similar body compositions determined using LI, H, and L suggest that LI determines body composition as effectively as H and L. High correlations between the three calipers support this notion. Similar results between LI and HW/ADP subgroup suggest that the LI caliper may be a valid method of measuring body composition. Overall, performance by IX was similar to EX and suggests similar ease of use for all three calipers

Perspective: A Magazine for Different People

Perspective was published by undergraduate students at UND in April 1978. The lone issue featured articles about the culture and history of Sioux Indians, an interview with an African student and an African-American student, domestic abuse of women, the development of new energy resources in North Dakota, and the new Hughes Fine Arts Center. Photographs, cartoons, poetry and prose were also included.https://commons.und.edu/und-books/1065/thumbnail.jp

Percutaneous Delivery of Thalidomide and Its N-Alkyl Analogs

Purpose . The purpose of this study was to determine the permeation parameters of thalidomide and three of its N -alkyl analogs and to establish a correlation between the physicochemical properties of these compounds and their percutaneous rates of absorption.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41491/1/11095_2004_Article_370433.pd