Ensuring equity: Pharmacogenetic implementation in rural and tribal communities.

Implementation strategies for pharmacogenetic testing have been largely limited to major academic medical centers and large health systems, threatening to exacerbate healthcare disparities for rural and tribal populations. There exists a need in Montana (United States)-a state where two-thirds of the population live in rural areas and with a large proportion of tribal residents-to develop novel strategies to make pharmacogenetic testing more broadly available. We established partnerships between University of Montana (UM) and three early adopter sites providing patient-centered care to historically neglected populations. We conducted 45 semi-structured interviews with key stakeholders at each site and solicited participant feedback on the utility of a centralized pharmacogenetic service at UM offering consultations to patients and providers statewide via telehealth. For settings serving rural patients-tribal and non-tribal-participants described healthcare facilities without adequate infrastructure, personnel, and funding to implement pharmacogenetic services. Participants serving tribal communities stressed the need for ethical practices for collecting biospecimens and returning genetic results to patients, largely due to historical and contemporary traumas experienced by tribal populations with regard to genetic research. Participants expressed that pharmacogenetic testing could benefit patients by achieving therapeutic benefit sooner, reducing the risk of side effects, and improving adherence outcomes for patients with limited access to follow-up services in remote areas. Others expressed concern that financial barriers to pharmacogenetic testing for patients of lower socioeconomic status would further exacerbate inequities in care. Participants valued the role of telehealth to deliver pharmacogenetic consults from a centralized service at UM, describing the ability to connect providers and patients to resources and expertise as imperative to driving successful pharmacogenetic implementation. Our results support strategies to improve access to pharmacogenetic testing for neglected patient populations and create opportunities to reduce existing healthcare inequities. By exploring critical challenges for pharmacogenetic implementation focused on serving underserved communities, this work can help guide equitable frameworks to serve as a model for other resource-limited settings looking to initiate pharmacogenetic testing.

Food dyes as P-glycoprotein modulators.

The drug transporter P-glycoprotein (P-gp) is often investigated in drug-interaction studies because the activity is modulated by a wide variety of xenobiotics including drugs, herbal products, and food components. In this study, we tested six common arylsulfonate food dyes-allura red, carmoisine, ponceau 4R, quinolone yellow, sunset yellow, and tartrazine-as activators and inhibitors of P-gp activity in vitro. The dyes were studied as P-gp activators by measuring ATPase activity in P-gp-expressing membranes. Compared to verapamil, a known activator of P-gp, the six food dyes showed no stimulatory activity. The potential for these six food dyes to act as P-gp inhibitors was tested in an intracellular efflux assay with P-gp-expressing cells. Compared to GF120918, a known P-gp inhibitor, there was no inhibitory activity for these six food dyes. The six food dyes tested do not interact with P-gp in vitro and, therefore, are unlikely cause clinical drug-food dye interactions. Further investigation is necessary to determine whether these food dyes could interact with other drug transporters.

Preparation and characterization of diethoxy- and monoethoxy phosphylated ('aged') serine haptens and use in the production of monoclonal antibodies.

In this study, the first mechanism-based monoclonal antibodies have been produced that recognize and differentiate diethoxy- and monoethoxyphosphorylated serine residues. Haptens were synthesized as the stable phosphonate form of phosphoserine esters to improve the immunoresponse. Following condensation with a glutaric anhydride to link the phosphoserine moieties to carrier protein, the hapten densities attached to bovine serum albumin and keyhole limpet henocyanin were determined by partial trypsin digestion and MALDI mass spectrometry, and confirmed using a fluorescent assay (FITC) to quantify unmodified lysine residues. The conjugation reactions were pH optimized to improve hapten density. Screening of subclones led to the identification of two monoclonal antibodies: (a) N257/25.11 that specifically recognizes (EtO)2P(O)-Ser as the phosphylated or inhibited form, and (b) N262/16 that recognizes (EtO)(HO)P(O)-Ser as the 'aged' form. Analysis of blood samples treated with paraoxon (EtO)2P(O)-OPhNO2 showed a concentration dependent recognition of the phosphylated form.

Oxidative stress resulting from exposure of a human salivary gland cells to paraoxon: an in vitro model for organophosphate oral exposure.

Organophosphate (OP) compounds are used as insecticides, acaricides, and chemical agents and share a common neurotoxic mechanism of action. The biochemical alterations leading to many of the deleterious effects have been studied in neuronal cell lines, however, non-neuronal toxic effects of OPs are far less well characterized in vitro, and specifically in cell lines representing oral routes of exposure. To address this void, the human salivary gland (HSG) cell line, representing likely interactions in the oral cavity, was exposed to the representative OP paraoxon (PX; O,O-diethyl-p-nitrophenoxy phosphate) over a range of concentrations (0.01-100 µM) and analyzed for cytotoxicity. PX induced cytotoxicity in HSG cells at most of the exposure concentrations as revealed by MTT assay, however, the release of LDH only occurred at the highest concentration of PX tested (100 µM) at 48 h. Slight increases in cellular ATP levels were measured in PX-exposed (10 µM) HSG cells at 24 h. Exposing HSG cells to 10 µM PX also led to an increase in DNA fragmentation prior to loss of cellular membrane integrity implicating reactive oxygen species (ROS) as a trigger of toxicity. The ROS genes gss, gstm2, gstt2 and sod2 were upregulated, and the presence of superoxide following 10 µM PX exposure was determined via dihydroethidium fluorescence studies further implicating PX-induced oxidative stress in HSG cells.

Fluorescent probes of the isoxazole-dihydropyridine scaffold: MDR-1 binding and homology model.

Isoxazole-1,4-dihydropyridines (IDHPs) were tethered to fluorescent moieties using double activation via a lanthanide assisted Weinreb amidation. IDHP-fluorophore conjugate 3c exhibits the highest binding to date for IDHPs at the multidrug-resistance transporter (MDR-1), and IDHP-fluorophore conjugates 3c and 7 distribute selectively in SH-SY5Y cells. A homology model for IDHP binding at MDR-1 is presented which represents our current working hypothesis.

Paraoxon-induced protein expression changes to SH-SY5Y cells.

SH-SY5Y neuroblastoma cells were examined to determine changes in protein expression following exposure to the organophosphate paraoxon (O,O-diethyl-p-nitrophenoxy phosphate). Exposure of SH-SY5Y cells to paraoxon (20 µM) for 48 h showed no significant change in cell viability as established using an MTT assay. Protein expression changes from the paraoxon-treated SH-SY5Y cells were determined using a comparative, subproteome approach by fractionation into cytosolic, membrane, nuclear, and cytoskeletal fractions. The fractionated proteins were separated by 2D-PAGE, identified by MALDI-TOF mass spectrometry, and expression changes determined by densitometry. Over 400 proteins were separated from the four fractions, and 16 proteins were identified with altered expression ≥1.3-fold including heat shock protein 90 (-1.3-fold), heterogeneous nuclear ribonucleoprotein C (+2.8-fold), and H(+) transporting ATP synthase beta chain (-3.1-fold). Western blot analysis conducted on total protein isolates confirmed the expression changes in these three proteins.

Subacute developmental exposure of zebrafish to the organophosphate pesticide metabolite, chlorpyrifos-oxon, results in defects in Rohon-Beard sensory neuron development.

Organophosphate pesticides (OPs) are environmental toxicants known to inhibit the catalytic activity of acetylcholinesterase (AChE) resulting in hypercholinergic toxicity symptoms. In developing embryos, OPs have been hypothesized to affect both cholinergic and non-cholinergic pathways. In order to understand the neurological pathways affected by OP exposure during embryogenesis, we developed a subacute model of OP developmental exposure in zebrafish by exposing embryos to a dose of the OP metabolite chlorpyrifos-oxon (CPO) that is non-lethal and significantly inhibited AChE enzymatic activity compared to control embryos (43% at 1 day post-fertilization (dpf) and 11% at 2dpf). Phenotypic analysis of CPO-exposed embryos demonstrated that embryonic growth, as analyzed by gross morphology, was normal in 85% of treated embryos. Muscle fiber formation was similar to control embryos as analyzed by birefringence, and nicotinic acetylcholine receptor (nAChR) cluster formation was quantitatively similar to control embryos as analyzed by α-bungarotoxin staining. These results indicate that partial AChE activity during the early days of zebrafish development is sufficient for general development, muscle fiber, and nAChR development. Rohon-Beard (RB) sensory neurons exhibited aberrant peripheral axon extension and gene expression profiling suggests that several genes responsible for RB neurogenesis are down-regulated. Stability of CPO in egg water at 28.5 °C was determined by HPLC-UV-MS analysis which revealed that the CPO concentration used in our studies hydrolyzes in egg water with a half-life of 1 day. The result that developmental CPO exposure affected RB neurogenesis without affecting muscle fiber or nAChR cluster formation demonstrates that zebrafish are a strong model system for characterizing subtle neurological pathologies resulting from environmental toxicants.

Thionate versus Oxon: comparison of stability, uptake, and cell toxicity of ((14)CH(3)O)(2)-labeled methyl parathion and methyl paraoxon with SH-SY5Y cells.

The stability, hydrolysis, and uptake of the organophosphates methyl parathion and methyl paraoxon were investigated in SH-SY5Y cells. The stabilities of ((14)CH(3)O)(2)-methyl parathion ((14)C-MPS) and ((14)CH(3)O)(2)-methyl paraoxon ((14)C-MPO) at 1 microM in culture media had similar half-lives of 91.7 and 101.9 h, respectively. However, 100 microM MPO caused >95% cytotoxicity at 24 h, whereas 100 microM MPS caused 4-5% cytotoxicity at 24 h ( approximately 60% cytotoxicity at 48 h). Greater radioactivity was detected inside cells treated with MPO as compared to MPS, although >80% of the total MPO uptake was primarily dimethyl phosphate (DMP). Maximum uptake was reached after 48 h of (14)C-MPS or (14)C-MPO exposure with total uptakes of 1.19 and 1.76 nM/10(6) cells for MPS and MPO, respectively. The amounts of MPS and MPO detected in the cytosol after 48 h of exposure time were 0.54 and 0.37 nM/10(6) cells, respectively.

Mass spectrometric analyses of organophosphate insecticide oxon protein adducts.

OBJECTIVE: Organophosphate (OP) insecticides continue to be used to control insect pests. Acute and chronic exposures to OP insecticides have been documented to cause adverse health effects, but few OP-adducted proteins have been correlated with these illnesses at the molecular level. Our aim was to review the literature covering the current state of the art in mass spectrometry (MS) used to identify OP protein biomarkers. DATA SOURCES AND EXTRACTION: We identified general and specific research reports related to OP insecticides, OP toxicity, OP structure, and protein MS by searching PubMed and Chemical Abstracts for articles published before December 2008. DATA SYNTHESIS: A number of OP-based insecticides share common structural elements that result in predictable OP-protein adducts. The resultant OP-protein adducts show an increase in molecular mass that can be identified by MS and correlated with the OP agent. Customized OP-containing probes have also been used to tag and identify protein targets that can be identified by MS. CONCLUSIONS: MS is a useful and emerging tool for the identification of proteins that are modified by activated organophosphate insecticides. MS can characterize the structure of the OP adduct and also the specific amino acid residue that forms the key bond with the OP. Each protein that is modified in a unique way by an OP represents a unique molecular biomarker that with further research can lead to new correlations with exposure.

Prdm1a is necessary for posterior pharyngeal arch development in zebrafish.

Multiple tissue interactions and signaling within the pharyngeal arches are required for development of the craniofacial skeleton. Here, we focus on the role of the transcription factor prdm1a in the differentiation of the posterior skeleton. prdm1a is expressed in the presumptive pharyngeal arch region and later in an endodermal pouch, the otic vesicle, and pharyngeal teeth. prdm1a mutants display a reduction in pharyngeal arch markers, a loss of posterior ceratobranchial cartilages, and a reduction in most neural crest-derived dermal bones. This is likely caused by a decrease in the number of proliferating cells but not an increase in cell death. Finally, a reduction in two key developmental signaling pathways, Fgf and retinoic acid, alters prdm1a expression, suggesting that prdm1a expression is mediated by these signaling pathways to pattern the posterior craniofacial skeleton. Together, these results indicate an essential role for prdm1a in the development of the zebrafish craniofacial skeleton.

Analysis and sequencing of the active-site peptide from native and organophosphate-inactivated acetylcholinesterase by electrospray ionization, quadrupole/time-of-flight (QTOF) mass spectrometry.

A method to identify and sequence recombinant mouse acetylcholinesterase (rMoAChE) including the native and organophosphate-modified active-site peptides was developed using capillary liquid chromatography with electrospray ionization, quadrupole/time-of-flight mass spectrometry. Addition of 2-propanol to the reversed-phase gradient system and a decreased gradient slope improved the peptide resolution and the signal of the active-site peptide. The highest protein coverage and active-site peptide signal were achieved when the rMoAChE:chymotrypsin ratio of 5:1 was used with digestion at 37 degrees C. rMoAChE and the active-site peptide were identified and sequenced from chymotryptic digests of native, methyl paraoxon-, and ethyl paraoxon-inactivated rMoAChE showing unequivocally that the exact modification site was the active-site serine.

Differential localization of acetylcholinesterase in neuronal and non-neuronal cells.

Acetylcholinesterase (AChE) expression is regulated in cell types at the transcriptional and translational levels. In this study, we characterized and compared AChE catalytic activity, mRNA, protein expression, and protein localization in a variety of neuronal (SH-SY5Y neuroblastoma and primary cerebellar granule neurons (CGN)) and non-neuronal (LLC-MK2, HeLa, THP-1, and primary astrocytes) cell types. All cell lines expressed AChE catalytic activity; however the levels of AChE-specific activity were higher in neuronal cells than in the non-neuronal cell types. CGN expressed significantly more AChE activity than SH-SY5Y cells. All cell lines analyzed expressed AChE protein at equivalent levels, as well as mRNA splice variants. Localization of AChE was characterized by immunofluorescence and confocal microscopy. SH-SY5Y, CGN, and nerve-growth factor-differentiated PC-12 cells exhibited a pattern of AChE localization characterized as diffuse in the cytoplasm and punctate staining along neurites and on the plasma membrane. The localization in HeLa, LLC-MK2, fibroblasts, and undifferentiated PC-12 cells was significantly different than in neuronal cells-AChE was intensely localized in the perinuclear region, without staining near or on the plasma membrane. Based on the evidence presented here, we hypothesize that the presence of AChE protein doesn't correlate with catalytic activity, and the diffuse cytoplasmic and plasma membrane localization of AChE is a property of neuronal cell types.

Differentiation between acetylcholinesterase and the organophosphate-inhibited form using antibodies and the correlation of antibody recognition with reactivation mechanism and rate.

Two types of polyclonal antibodies were generated from (a) a decapeptide sequence that includes the active site serine of acetylcholinesterase (anti-AChE10S) and (b) the identical decapeptide sequence phosphorylated at the active site serine of acetylcholinesterase (anti-AChE10SP). The anti-AChE10S antiserum was found to specifically recognize native, control, and vehicle-treated recombinant mouse AChE (rMoAChE) but did not recognize rMoAChE that was phosphorylated by the four organophosphate (OP) compounds tested. Conversely the anti-AChE10SP antiserum recognized phosphoserine rMoAChE that resulted from reaction with phosphorous oxychloride (POCl3) but did not recognize native or vehicle-treated rMoAChE. Anti-AChE10SP also did not recognize OP-AChE conjugates that resulted from the reaction of rMoAChE with other OP compounds that afford neutral or monoanionic phosphoserine groups thereby indicating a high specificity for a precise OP conjugate. Antisera recognition correlated well with the rates of enzyme inhibition, aging, and oxime-induced reactivation indicating these antisera can both quantify the extent and type of inhibition and also differentiate between select mechanisms of inhibition. The ability to discern mechanistic differences between native AChE and OP-AChE conjugates suggests that these antisera can be used to identify biomarkers of OP exposure in a mechanism-based approach.

Examination of cross-antigenicity of acetylcholinesterase and butyrylcholinesterase using anti-acetylcholinesterase antibodies.

Acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) share a high degree of homology and overlap in several biochemical properties. This study aimed to compare and contrast the antigenic reactivity of AChE and BuChE with several polyclonal antibodies. We have performed a detailed analysis of AChE and BuChE enzymatic activities with different substrates and different inhibitors. Immunoassays conducted with polyclonal amino-terminus-specific anti-AChE antibodies were selective for mouse and electric eel AChE (EEAChE). Polyclonal carboxy-terminus-specific anti-AChE antibodies reacted with EEAChE and human BuChE, indicating an unexpected cross-reactivity. Polyclonal antisera raised against the whole AChE protein cross-reacted with horse BuChE, but not human BuChE. These data demonstrate that AChE and BuChE are immunologically similar.