Mechanisms of ligand-receptor interactions of the dopamine D2L receptor and their relation to functional selectivity

Binding and functional studies indicate that some agonists are capable of differentially activating pathways linked to a single receptor isoform. In cases where known mechanisms like other receptors or receptor reserve are ruled out, this phenomenon is referred to as “functional selectivity,” “agonist directed trafficking,” and a variety of other terms. Rather than viewing receptors in a traditional way as digital entities (i.e., one or more active or inactive states), functional selectivity posits that a receptor can be induced into unique conformations that may lead to different patterns of activation of functional responses linked to a single receptor. This dissertation elucidates the molecular mechanisms that explain why some ligands can differentially activate the effector pathways coupled to the human D2L receptor. The focus will be to discern the structural interactions of the hD2L receptor with such functionally selective ligands, and how these interactions result in selective activation of effector pathways. Computationally-selected point mutations of the D2L receptor were made, and detailed analysis of both binding and function made for a series of rationally selected ligands, emphasizing compounds that were relatively rigid and had fewer degrees of freedom in possible docking poses. Functional assays tested the intrinsic activity and potency for GTPγS binding, inhibition of forskolin-stimulated cAMP, phosphorylation of MAPK, and release of [3H]-arachidonic acid. Results from this dissertation provide evidence to support the hypothesis that ligand-selective interactions with specific residues of the receptor can induce conformational changes that lead to a characteristic pattern of activation of one of more signaling pathways. Developing a structure-based understanding of functional selectivity will provide general insight into the mechanisms of GPCR activation, and may also open the door to design of small molecules with desired patterns of functional effects at a single receptor

Detecting Aflatoxicosis in Broilers in the Evaluation of Clay-based, Toxin-binding Feed Additives

The objectives of this research were to evaluate common biological measures of aflatoxicosis in broilers (such as growth rate and relative organ weights) along with variables such as hepatic gene expression and aflatoxin residues in the liver, pursuant to identifying a more sensitive biological assay that will allow researchers to conduct three-week broiler trials at aflatoxin concentrations <1000 ppb, prior to significant changes in the growth rate or relative organ weights. This will help us both better understand how aflatoxicosis presents in broilers, as well as help us evaluate the efficacy of clay-based binders for their ability to ameliorate aflatoxicosis under experimental conditions. In the first study, a recently mined calcium bentonite clay (TX4) was evaluated against Novasil™. Both clays appeared able to sequester aflatoxin, and overall TX4 appeared capable of ameliorating aflatoxicosis comparable to Novasil™. In the second study, growth and relative organ weight data were compared with the gene expression of hepatic enzymes known to detoxify aflatoxin B1 in broilers that had consumed a wide range of aflatoxin concentrations. When gene expression data from liver samples were analyzed, the genotypic effect of aflatoxin on the CYP1A1 and CYP2H1 isoforms simply mirrored the phenotypic effects seen in the growth and relative organ weights, suggesting that this variable was not any more sensitive than the more traditional ones. The third study evaluated the TX4 clay when in diets containing <1000 ppb aflatoxin. Although weight gain was unaffected by aflatoxin at these lower levels (after three weeks on treatment diets, body weights between the 0 ppb treatment and the 700 ppb treatment only varied by 4%), there were negative effects on feed conversion and productivity index and there was an increase in the relative weights of the liver and kidney. The inclusion of TX4 to the treatment diets did not offer any amelioration from the main effects of aflatoxin. Finally, a study was conducted to evaluate the effects of TX4 clay when using residues of aflatoxin B1 in the liver as the primary variable of interest. Results after one week on treatment diets showed that TX4 was effective at reducing the accumulation of aflatoxin B1 residues in liver. However, after the first week, liver residue data were not any more sensitive in evaluating aflatoxin or clay effects when compared to the “traditional” measures of growth performance and organ weights. Also, these results indicate that the clearance time required to remove aflatoxin residues from the liver is less than one week on a clean corn diet. Based on these evaluations, attempts to characterize a more sensitive, sentinel-type response to aflatoxin exposure in broilers were not any more successful at evaluating aflatoxicosis than was the common bioassay measures such as growth rate and relative organ weights. These studies (by contaminating corn with aflatoxigenic species of Aspergillus) were able to find significant main effects for aflatoxin at lower concentrations (≤1000 ppb) than had been previously reported by the studies that included inoculated rice

CO2-plume geothermal: Power net generation from 3D fluvial aquifers

Previously CO2, as a heat-extraction fluid, has been proposed as a superior substitute for brine in geothermal energy extraction. Hence, the new concept of CO2-plume geothermal (CPG) is suggested to generate heat from geothermal aquifers using CO2 as the working fluid. In January 2015, a CPG-thermosiphon system commenced at the SECARB Cranfield Site, Mississippi. By utilising CO2, the demand for the pumping power is greatly reduced due to the thermosiphon effect at the production well. However, there are still parameters such as aquifer thermal depletion, required high injection rates, and CO2-plume establishment time, that hinder CPG from becoming viable. Moreover, the fluvial nature of sedimentary aquifers significantly affects the heat and mass transfer inside the aquifer, as well as the system performance. In the present study, a direct-CO2 thermosiphon system is considered that produces electricity from a 3D braided-fluvial sedimentary aquifer by providing an excess pressure at the surface that is used in the turbine. The system performance and net power output are analyzed in 15 3D fluvial heterogeneous - with channels’ widths of 50, 100, and 150 m - and three homogeneous aquifer realizations with different CO2 injection rates. It is observed that the presence of fluvial channels significantly increases the aquifer thermal depletion pace (22-120%) and therefore, reduces the system’s performance up to about 75%. Additionally, it is found that the CPG system with the CO2 injection rate of 50 kg/s and the I-P line parallel to the channels provides the maximum cycle operation time (44 years), as well as the optimum performance for the heterogeneous cases of the present study by providing about 0.06-0.12 TWh energy during the simulation time of 50 years. Also, to prevent rapid drops in excess pressure, a system with a yearly adjustable injection rate is implemented, which prevents the production well bottomhole temperature to fall below 80 ◦C

Real time x-ray studies during nanostructure formation on silicon via low energy ion beam irradiation using ultrathin iron films

Real time grazing incidence small angle x-ray scattering and x-ray fluorescence (XRF) are used to elucidate nanodot formation on silicon surfaces during low energy ion beam irradiation of ultrathin iron-coated silicon substrates. Four surface modification stages were identified: (1) surface roughening due to film erosion, (2) surface smoothing and silicon-iron mixing, (3) structure formation, and (4) structure smoothing. The results conclude that 2.5 x 10(15) iron atoms in a 50 nm depth triggers surface nanopatterning with a correlated nanodots distance of 25 nm. Moreover, there is a wide window in time where the surface can have correlated nanostructures even after the removal of all the iron atoms from the sample as confirmed by XRF and ex-situ x-ray photoelectron spectroscopy (XPS). In addition, in-situ XPS results indicated silicide formation, which plays a role in the structure formation mechanism. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4773202

Size Matters: Microservices Research and Applications

In this chapter we offer an overview of microservices providing the introductory information that a reader should know before continuing reading this book. We introduce the idea of microservices and we discuss some of the current research challenges and real-life software applications where the microservice paradigm play a key role. We have identified a set of areas where both researcher and developer can propose new ideas and technical solutions.Comment: arXiv admin note: text overlap with arXiv:1706.0735

Candidate gene polymorphisms study between human African trypanosomiasis clinical phenotypes in Guinea

Human African trypanosomiasis (HAT), a lethal disease induced by Trypanosoma brucei gambiense, has a range of clinical outcomes in its human host in West Africa: an acute form progressing rapidly to second stage, spontaneous self-cure and individuals able to regulate parasitaemia at very low levels, have all been reported from endemic foci. In order to test if this clinical diversity is influenced by host genetic determinants, the association between candidate gene polymorphisms and HAT outcome was investigated in populations from HAT active foci in Guinea.Samples were collected from 425 individuals; comprising of 232 HAT cases, 79 subjects with long lasting positive and specific serology but negative parasitology and 114 endemic controls. Genotypes of 28 SNPs in eight genes passed quality control and were used for an association analysis. IL6 rs1818879 allele A (p = 0.0001, OR = 0.39, CI95 = [0.24-0.63], BONF = 0.0034) was associated with a lower risk of progressing from latent infection to active disease. MIF rs36086171 allele G seemed to be associated with an increased risk (p = 0.0239, OR = 1.65, CI95 = [1.07-2.53], BONF = 0.6697) but did not remain significant after Bonferroni correction. Similarly MIF rs12483859 C allele seems be associated with latent infections (p = 0.0077, OR = 1.86, CI95 = [1.18-2.95], BONF = 0.2157). We confirmed earlier observations that APOL1 G2 allele (DEL) (p = 0.0011, OR = 2.70, CI95 = [1.49-4.91], BONF = 0.0301) is associated with a higher risk and APOL1 G1 polymorphism (p = 0.0005, OR = 0.45, CI95 = [0.29-0.70], BONF = 0.0129) with a lower risk of developing HAT. No associations were found with other candidate genes.Our data show that host genes are involved in modulating Trypanosoma brucei gambiense infection outcome in infected individuals from Guinea with IL6 rs1818879 being associated with a lower risk of progressing to active HAT. These results enhance our understanding of host-parasite interactions and, ultimately, may lead to the development of new control tools

Age-related changes in eye lens biomechanics, morphology, refractive index and transparency

Life-long eye lens function requires an appropriate gradient refractive index, biomechanical integrity and transparency. We conducted an extensive study of wild-type mouse lenses 1-30 months of age to define common age-related changes. Biomechanical testing and morphometrics revealed an increase in lens volume and stiffness with age. Lens capsule thickness and peripheral fiber cell widths increased between 2 to 4 months of age but not further, and thus, cannot account for significant age-dependent increases in lens stiffness after 4 months. In lenses from mice older than 12 months, we routinely observed cataracts due to changes in cell structure, with anterior cataracts due to incomplete suture closure and a cortical ring cataract corresponding to a zone of compaction in cortical lens fiber cells. Refractive index measurements showed a rapid growth in peak refractive index between 1 to 6 months of age, and the area of highest refractive index is correlated with increases in lens nucleus size with age. These data provide a comprehensive overview of age-related changes in murine lenses, including lens size, stiffness, nuclear fraction, refractive index, transparency, capsule thickness and cell structure. Our results suggest similarities between murine and primate lenses and provide a baseline for future lens aging studies

Reducing the Risk of Hospitalization for Nursing Home Residents: Effects and Facility Variation From OPTIMISTIC

Objectives The Optimizing Patient Transfers, Impacting Medical Quality, and Improving Symptoms: Transforming Institutional Care (OPTIMISTIC) project led to significant decreases in potentially avoidable hospitalizations of long-stay nursing facility residents in external evaluation. The purpose of this study was to quantify hospitalization risk from the start of the project and describe the heterogeneity of the enrolled facilities in order to better understand the context for successful implementation. Design Pre-post analysis design of a prospective intervention within a single group. Setting and Participants A total of 4320 residents in the 19 facilities were included from admission until time to the first hospitalization. Measures Data were extracted from Minimum Data Set assessments and linked with facility-level covariates from the LTCFocus.org data set. Kaplan-Meier and Cox proportional hazards regression were used to assess risk of hospitalization during the preintervention period (2011-2012), a “ramp-up” period (2013-2014), and an intervention period (2015-2016). Results The cohort consisted of 4230 long-stay nursing facility residents. Compared with the preintervention period, residents during the intervention period had an increased probability of having no hospitalizations within 1 year, increasing from 0.51 to 0.57, which was statistically significant ( P < .001). In adjusted Cox models, the risk of hospitalization was lower in the ramp-up period compared to the pre-period [hazard ratio (HR) 0.85, 95% confidence interval (CI) 0.75-0.95] and decreased further during the intervention period (HR 0.74, 95% CI 0.65-0.84). Conclusions and Implications As part of a large multisite demonstration project, OPTIMISTIC has successfully reduced hospitalizations. However, this study highlights the magnitude and extent to which results differ across facilities. Implementing the OPTIMISTIC program was associated with a 16% risk reduction after the first 18 months and continued to a final risk reduction of 26% after 5½ years. Although this model of care reduces hospitalizations overall, facility variation should be expected