Apolipoprotein E competitively inhibits receptor-dependent low density lipoprotein uptake by the liver but has no effect on cholesterol absorption or synthesis in the mouse.

This study examines the question of whether apolipoprotein E (apoE) alters steady-state concentrations of plasma cholesterol carried in low density lipoproteins (LDL-C) by acting as a competitive inhibitor of hepatic LDL uptake or by altering the rate of net cholesterol delivery from the intestinal lumen to the liver. To differentiate between these two possibilities, rates of cholesterol absorption and synthesis and the kinetics of hepatic LDL-C transport were measured in vivo in mice with either normal (apoE+/+) or zero (apoE-/-) levels of circulating apoE. Rates of cholesterol absorption were essentially identical in both genotypes and equaled approximately 44% of the daily dietary load of cholesterol. This finding was consistent with the further observation that the rates of cholesterol synthesis in the liver (approximately 2,000 nmol/h) and extrahepatic tissues (approximately 3,000 nmol/h) were also essentially identical in the two groups of mice. However, the apparent Michaelis constant for receptor-dependent hepatic LDL-C uptake was markedly lower in the apoE-/- mice (44 +/- 4 mg/dl) than in the apoE+/+ animals (329 +/- 77 mg/dl) even though the maximal transport velocity for this uptake process was essentially the same (approximately 400 micrograms/h per g) in the two groups of mice. These studies, therefore, demonstrate that apoE-containing lipoproteins can act as potent competitive inhibitors of hepatic LDL-C transport and so can significantly increase steady-state plasma LDL-C levels. This apolipoprotein plays no role, however, in the regulation of cholesterol absorption, sterol biosynthesis, or hepatic LDL receptor number, at least in the mouse.

Fluorescence energy transfer dye-labeled primers for DNA sequencing and analysis.

Fluorescent dye-labeled DNA primers have been developed that exploit fluorescence energy transfer (ET) to optimize the absorption and emission properties of the label. These primers carry a fluorescein derivative at the 5' end as a common donor and other fluorescein and rhodamine derivatives attached to a modified thymidine residue within the primer sequence as acceptors. Adjustment of the donor-acceptor spacing through the placement of the modified thymidine in the primer sequence allowed generation of four primers, all having strong absorption at a common excitation wavelength (488 nm) and fluorescence emission maxima of 525, 555, 580, and 605 nm. The ET efficiency of these primers ranges from 65% to 97%, and they exhibit similar electrophoretic mobilities by gel electrophoresis. With argon-ion laser excitation, the fluorescence of the ET primers and of the DNA sequencing fragments generated with ET primers is 2- to 6-fold greater than that of the corresponding primers or fragments labeled with single dyes. The higher fluorescence intensity of the ET primers allows DNA sequencing with one-fourth of the DNA template typically required when using T7 DNA polymerase. With single-stranded M13mp18 DNA as the template, a typical sequencing reaction with ET primers on a commercial sequencer provided DNA sequences with 99.8% accuracy in the first 500 bases. ET primers should be generally useful in the development of other multiplex DNA sequencing and analysis methods.

Fire-resistance, physical, and mechanical characterization of particleboard containing Oceanic Posidonia waste

In this work, particleboards manufactured with Oceanic Posidonia waste and bonded with cement are investigated. The particleboards are made with 3/1.5/0.5 parts of cement per part of Posidonia waste. The physical properties of bulk density, swelling, surface absorption, and dimensional changes due to relative humidity as well as the mechanical properties of modulus of elasticity, bending strength, surface soundness, perpendicular tensile strength and impact resistance are studied. In terms of the above properties, the best results were obtained for particleboards with high cement content and when the waste “leaves” are treated (crushed) before board fabrication, due to internal changes to the board structure under these conditions. Based on the results of fire tests, the particleboard is non-flammable without any fire-resistant treatment.

Tungsten coil atomic emission spectrometry combined with dispersive liquid–liquid microextraction: A synergistic association for chromium determination in water samples

A novel and environment friendly analytical method is reported for total chromium determination and chromium speciation in water samples, whereby tungsten coil atomic emission spectrometry (WCAES) is combined with in situ ionic liquid formation dispersive liquid–liquid microextraction (in situ IL-DLLME). A two stage multivariate optimization approach has been developed employing a Plackett–Burman design for screening and selection of the significant factor involved in the in situ IL-DLLME procedure, which was later optimized by means of a circumscribed central composite design. The optimum conditions were complexant concentration: 0.5% (or 0.1%); complexant type: DDTC; IL anion: View the MathML sourcePF6−; [Hmim][Cl] IL amount: 60 mg; ionic strength: 0% NaCl; pH: 5 (or 2); centrifugation time: 10 min; and centrifugation speed: 1000 rpm. Under the optimized experimental conditions the method was evaluated and proper linearity was obtained with a correlation coefficient of 0.991 (5 calibration standards). Limits of detection and quantification for both chromium species were 3 and 10 µg L−1, respectively. This is a 233-fold improvement when compared with chromium determination by WCAES without using preconcentration. The repeatability of the proposed method was evaluated at two different spiking levels (10 and 50 µg L−1) obtaining coefficients of variation of 11.4% and 3.6% (n=3), respectively. A certified reference material (SRM-1643e NIST) was analyzed in order to determine the accuracy of the method for total chromium determination and 112.3% and 2.5 µg L−1 were the recovery (trueness) and standard deviation values, respectively. Tap, bottled mineral and natural mineral water samples were analyzed at 60 µg L−1 spiking level of total Cr content at two Cr(VI)/Cr(III) ratios, and relative recovery values ranged between 88% and 112% showing that the matrix has a negligible effect. To our knowledge, this is the first time that combines in situ IL-DLLME and WCAES.

U, FE, AND LI ISOTOPE RATIOS IN THE MINERALIZED AND BARREN AREAS OF THE KOMBOLGIE BASIN

The Paleo- to Meso-Proterozoic Jabiluka unconformity related uranium mine is located within the Alligator River Uranium Field, found in the Northern Territories, Australia. The uranium ore is hosted in the late middle Paleoproterozoic Cahill Formation, which is unconformably overlain by a group of unmetamorphosed conglomerates known as the Kombolgie subgroup. The Kombolgie subgroup provided the source for oxidized basinal brines, carrying U as the mobile form U(VI), which interacted with reducing lithologies in the Cahill formation, thus reducing U(VI) to the solid U(IV), and leading to the precipitation of uraninite (UO2). In order to characterize fluid interaction with the ore body and compare that to areas without mineralization, several isotopic tracers were studied on a series of clay samples from drill core at Jabiluka as well as in barren areas throughout the ARUF. Among the potential tracers, three were selected: U (redox sensitive and recent fluid mobilization), Fe (redox sensitive), and Li (fractionated by hydrothermal fluids and adsorption reactions). δ238U values were found to be closely linked to the mineralogy, with samples with higher K/Al ratios (indicating high illite and low chlorite concentrations) having higher δ238U values. This demonstrates that 235U preferentially absorbs onto the surface of chlorite during hydrothermal circulation. In addition, δ234U values lie far from secular equilibrium (δ234U of 30‰), indicating there was addition or removal of 234U from the surface of the samples from recent (<2.5Ma) interactions of mobile fluids. δ57Fe values were found to be related to lithology and spatially to known uranium deposits. Decreasing δ57Fe values were found with increasing depth to the unconformity in a drill hole directly above the ore zone, but not in drill holes in the barren area. Similarly to δ238U, δ7Li is found to correlate with mineralogy, with higher δ7Li values associated with samples with more chlorite. In addition, higher δ7Li values are found at greater depth throughout the basin, indicating that the direction of the mineralizing fluid circulation was upwards from the Cahill formation to the Kombolgie subgroup.

Synthesis, Modification, and Application of Siloxane Materials for Environmental Sensing

As human populations and resource consumption increase, it is increasingly important to monitor the quality of our environment. While laboratory instruments offer useful information, portable, easy to use sensors would allow environmental analysis to occur on-site, at lower cost, and with minimal operator training. We explore the synthesis, modification, and applications of modified polysiloxane in environmental sensing. Multiple methods of producing modified siloxanes were investigated. Oligomers were formed by using functionalized monomers, producing siloxane materials containing silicon hydride, methyl, and phenyl side chains. Silicon hydride-functionalized oligomers were further modified by hydrosilylation to incorporate methyl ester and naphthyl side chains. Modifications to the siloxane materials were also carried out using post-curing treatments. Methyl ester-functionalized siloxane was incorporated into the surface of a cured poly(dimethylsiloxane) film by siloxane equilibration. The materials containing methyl esters were hydrolyzed to reveal carboxylic acids, which could later be used for covalent protein immobilization. Finally, the siloxane surfaces were modified to incorporate antibodies by covalent, affinity, and adsorption-based attachment. These modifications were characterized by a variety of methods, including contact angle, attenuated total reflectance Fourier transform infrared spectroscopy, dye labels, and 1H nuclear magnetic resonance spectroscopy. The modified siloxane materials were employed in a variety of sensing schemes. Volatile organic compounds were detected using methyl, phenyl, and naphthyl-functionalized materials on a Fabry-Perot interferometer and a refractometer. The Fabry-Perot interferometer was found to detect the analytes upon siloxane extraction by deformation of the Bragg reflectors. The refractometer was used to determine that naphthyl-functionalized siloxanes had elevated refractive indices, rendering these materials more sensitive to some analytes. Antibody-modified siloxanes were used to detect biological analytes through a solid phase microextraction-mediated enzyme linked immunosorbent assay (SPME ELISA). The SPME ELISA was found to have higher analyte sensitivity compared to a conventional ELISA system. The detection scheme was used to detect Escherichia coli at 8500 CFU/mL. These results demonstrate the variety of methods that can be used to modify siloxanes and the wide range of applications of modified siloxanes has been demonstrated through chemical and biological sensing schemes.

Methods for the analysis of columbium and its alloys /

This report consists of the analytical procedures modified or developed at Pratt & Whitney Aircraft, CANEL, for the determination of alloying constituents and impurities in columbium and its alloys. Included are spectrophotometric methods for chromium, columbium, iron, molybdenum, tungsten, nickel, nitrogen and titanium; volumetric methods for chromium, vanadium and zirconium; emission and X-ray spectrographic methods for various alloying elements; a spectrographic method for zirconium and trace impurities and miscellaneous methods for aluminum, carbon, oxygen and hydrogen.

Optics and Optoelectronics of Two-dimensional Semiconducting Monolayers and Heterostructures

Thesis (Ph.D.)--University of Washington, 2016-06

Using a non-invasive stable isotope tracer to measure the absorption of water in humans

The development of solutions that prevent dehydration or promote adequate re-hydration play a vital role in preventing fatigue during exercise, however, the methods commonly used to assess the hydration ability of such solutions are invasive and often assess the components of absorption separately. This paper describes using a non-invasive deuterium tracer technique that assesses gastric emptying and intestinal absorption simultaneously to evaluate the uptake of water during rest and exercise. The kinetics of absorption are further examined by mathematical modelling of the data generated. For the rest group, 0.05 g/kg of body weight of deuterium, contained in gelatine capsules, was ingested with ordinary tap water and saliva samples were collected every 5 min for one hour while the subject remained seated. The deuterium was administered as above for the exercise group but sample collection was during one hour of exercise on a treadmill at 55% of the subject's maximum heart rate. The enrichment data for each subject were mathematically modelled and the parameters obtained were compared across groups using an independent samples t-test. Compared with the rest condition, the exercise group showed delayed absorption of water as indicated by significant differences for the modelling parameters t(2), t(1/2), maximum absorption rate and solution absorption amount at t(1). Labelling with a deuterium tracer is a good measure of the relative rate ingested fluids are absorbed by the body. Mathematical modelling of the data generates rates of maximum absorption and allows calculation of the percentage of the solution that is absorbed at any given time during the testing period. Copyright (C) 2004 John Wiley Sons, Ltd.

Synthesis, characterization and DFT studies of the cobalt(III) complex of a tetrapodal pentadentate N4S donor ligand

The synthesis of the pentadentate ligand 2,6-bis(3,3-dimethyl-2,4-dioxocyclohexanyl)-4-thiaheptane (N(4)Samp) is described. The synthetic pathway involves the coupling of two 1,3-(dimethylenedioxy)-2-methyl-2-(methylene-p-toluenesulfonyl)propane moieties with sodium sulfide and subsequent synthetic elaboration to prepare the final N4S donor system. The cobalt(III) complex [Co(N(4)Samp)Cl](2+) has been prepared and subsequently crystallized as the tetrachlorozincate salt. The X-ray structure analysis confirms the pentadentate nature of the ligand and shows the thioether donor occupying one apex with four equivalent amine donors effectively occupying the equatorial plane of the molecule. The sixth coordination site is occupied by a chloro ligand. The electronic absorption and C-13 NMR spectra have been studied. DFT calculations have been employed to explore structural and mechanistic comparisons between [Co(N(4)Samp)Cl](2+) and an analogous pentaamine complex.

Lipid, sugar and liposaccharide based delivery systems 2

The vast majority of biologically active compounds will never be considered as potential drugs due to inherently poor bioavailability. This review discusses the progress in the development of chemical systems to improve the metabolic stability, absorption and physicochemical properties of potential drugs. Delivery systems that involve the conjugation of lipid and/or sugar moieties are highlighted, as well as novel methods of conjugation of these groups to drugs. The use of sugar molecules to target drugs to particular organs or cells is also discussed, as is the use of lipids in the growing area of gene delivery. This is an update of a previous review [1].

Increased duodenal expression of divalent metal transporter 1 and iron-regulated gene 1 in cirrhosis

Hepatic hemosiderosis and increased iron absorption are common findings in cirrhosis. It has been proposed that a positive relation exists between intestinal iron absorption and the development of hepatic hemosiderosis. The current study investigated the duodenal expression of the iron transport molecules divalent metal transporter 1 (DMT1 [IRE]), iron-regulated gene 1 (Ireg1 [ferroportin]), hephaestin, and duodenal cytochrome b (Dyctb) in 46 patients with cirrhosis and 20 control subjects. Total RNA samples were extracted from duodenal biopsy samples and the expression of the iron transport genes was assessed by ribonuclease protection assays. Expression of DMT1 and Ireg1 was increased 1.5 to 3-fold in subjects with cirrhosis compared with iron-replete control subjects. The presence of cirrhosis per se and serum ferritin (SF) concentration were independent factors that influenced the expression of DMT1. However, only SF concentration was independently associated with Iregl expression. In cirrhosis, the expression of DMT1 and Iregl was not related to the severity of liver disease or cirrhosis type. There was no correlation between the duodenal expression of DMT1 and Iregl and the degree of hepatic siderosis. In conclusion, the presence of cirrhosis is an independent factor associated with increased expression of DMT1 but not Iregl. The mechanism by which cirrhosis mediates this change in DMT1 expression has yet to be determined. Increased expression of DMT1 may play an important role in the pathogenesis of cirrhosis-associated hepatic iron overload.

Structural evolution in a hydrothermal reaction between Nb2O5 and NaOH solution: From Nb2O5 grains to microporous Na2Nb2O6 center dot(2)/3H2O fibers and NaNbO3 cubes

Niobium pentoxide reacts actively with concentrate NaOH solution under hydrothermal conditions at as low as 120 degrees C. The reaction ruptures the corner-sharing of NbO7 decahedra and NbO6 octahedra in the reactant Nb2O5, yielding various niobates, and the structure and composition of the niobates depend on the reaction temperature and time. The morphological evolution of the solid products in the reaction at 180 degrees C is monitored via SEM: the fine Nb2O5 powder aggregates first to irregular bars, and then niobate fibers with an aspect ratio of hundreds form. The fibers are microporous molecular sieve with a monoclinic lattice, Na2Nb2O6 center dot(2)/3H2O. The fibers are a metastable intermediate of this reaction, and they completely convert to the final product NaNbO3 Cubes in the prolonged reaction of 1 h. This study demonstrates that by carefully optimizing the reaction condition, we can selectively fabricate niobate structures of high purity, including the delicate microporous fibers, through a direct reaction between concentrated NaOH solution and Nb2O5. This synthesis route is simple and suitable for the large-scale production of the fibers. The reaction first yields poorly crystallized niobates consisting of edge-sharing NbO6 octahedra, and then the microporous fibers crystallize and grow by assembling NbO6 octahedra or clusters of NbO6 octahedra and NaO6 units. Thus, the selection of the fibril or cubic product is achieved by control of reaction kinetics. Finally, niobates with different structures exhibit remarkable differences in light absorption and photoluminescence properties. Therefore, this study is of importance for developing new functional materials by the wet-chemistry process.

A D-optimal designed population pharmacokinetic study of itraconazole capsules and solution in adults with cystic fibrosis

Background: Oral itraconazole (ITRA) is used for the treatment of allergic bronchopulmonary aspergillosis in patients with cystic fibrosis (CF) because of its antifungal activity against Aspergillus species. ITRA has an active hydroxy-metabolite (OH-ITRA) which has similar antifungal activity. ITRA is a highly lipophilic drug which is available in two different oral formulations, a capsule and an oral solution. It is reported that the oral solution has a 60% higher relative bioavailability. The influence of altered gastric physiology associated with CF on the pharmacokinetics (PK) of ITRA and its metabolite has not been previously evaluated. Objectives: 1) To estimate the population (pop) PK parameters for ITRA and its active metabolite OH-ITRA including relative bioavailability of the parent after administration of the parent by both capsule and solution and 2) to assess the performance of the optimal design. Methods: The study was a cross-over design in which 30 patients received the capsule on the first occasion and 3 days later the solution formulation. The design was constrained to have a maximum of 4 blood samples per occasion for estimation of the popPK of both ITRA and OH-ITRA. The sampling times for the population model were optimized previously using POPT v.2.0.[1] POPT is a series of applications that run under MATLAB and provide an evaluation of the information matrix for a nonlinear mixed effects model given a particular design. In addition it can be used to optimize the design based on evaluation of the determinant of the information matrix. The model details for the design were based on prior information obtained from the literature, which suggested that ITRA may have either linear or non-linear elimination. The optimal sampling times were evaluated to provide information for both competing models for the parent and metabolite and for both capsule and solution simultaneously. Blood samples were assayed by validated HPLC.[2] PopPK modelling was performed using FOCE with interaction under NONMEM, version 5 (level 1.1; GloboMax LLC, Hanover, MD, USA). The PK of ITRA and OH‑ITRA was modelled simultaneously using ADVAN 5. Subsequently three methods were assessed for modelling concentrations less than the LOD (limit of detection). These methods (corresponding to methods 5, 6 & 4 from Beal[3], respectively) were (a) where all values less than LOD were assigned to half of LOD, (b) where the closest missing value that is less than LOD was assigned to half the LOD and all previous (if during absorption) or subsequent (if during elimination) missing samples were deleted, and (c) where the contribution of the expectation of each missing concentration to the likelihood is estimated. The LOD was 0.04 mg/L. The final model evaluation was performed via bootstrap with re-sampling and a visual predictive check. The optimal design and the sampling windows of the study were evaluated for execution errors and for agreement between the observed and predicted standard errors. Dosing regimens were simulated for the capsules and the oral solution to assess their ability to achieve ITRA target trough concentration (Cmin,ss of 0.5-2 mg/L) or a combined Cmin,ss for ITRA and OH-ITRA above 1.5mg/L. Results and Discussion: A total of 241 blood samples were collected and analysed, 94% of them were taken within the defined optimal sampling windows, of which 31% where taken within 5 min of the exact optimal times. Forty six per cent of the ITRA values and 28% of the OH-ITRA values were below LOD. The entire profile after administration of the capsule for five patients was below LOD and therefore the data from this occasion was omitted from estimation. A 2-compartment model with 1st order absorption and elimination best described ITRA PK, with 1st order metabolism of the parent to OH-ITRA. For ITRA the clearance (ClItra/F) was 31.5 L/h; apparent volumes of central and peripheral compartments were 56.7 L and 2090 L, respectively. Absorption rate constants for capsule (kacap) and solution (kasol) were 0.0315 h-1 and 0.125 h-1, respectively. Comparative bioavailability of the capsule was 0.82. There was no evidence of nonlinearity in the popPK of ITRA. No screened covariate significantly improved the fit to the data. The results of the parameter estimates from the final model were comparable between the different methods for accounting for missing data, (M4,5,6)[3] and provided similar parameter estimates. The prospective application of an optimal design was found to be successful. Due to the sampling windows, most of the samples could be collected within the daily hospital routine, but still at times that were near optimal for estimating the popPK parameters. The final model was one of the potential competing models considered in the original design. The asymptotic standard errors provided by NONMEM for the final model and empirical values from bootstrap were similar in magnitude to those predicted from the Fisher Information matrix associated with the D-optimal design. Simulations from the final model showed that the current dosing regimen of 200 mg twice daily (bd) would provide a target Cmin,ss (0.5-2 mg/L) for only 35% of patients when administered as the solution and 31% when administered as capsules. The optimal dosing schedule was 500mg bd for both formulations. The target success for this dosing regimen was 87% for the solution with an NNT=4 compared to capsules. This means, for every 4 patients treated with the solution one additional patient will achieve a target success compared to capsule but at an additional cost of AUD $220 per day. The therapeutic target however is still doubtful and potential risks of these dosing schedules need to be assessed on an individual basis. Conclusion: A model was developed which described the popPK of ITRA and its main active metabolite OH-ITRA in adult CF after administration of both capsule and solution. The relative bioavailability of ITRA from the capsule was 82% that of the solution, but considerably more variable. To incorporate missing data, using the simple Beal method 5 (using half LOD for all samples below LOD) provided comparable results to the more complex but theoretically better Beal method 4 (integration method). The optimal sparse design performed well for estimation of model parameters and provided a good fit to the data.

Paediatric population pharmacokinetics of itraconazole and its active metabolite hydroxy-itraconazole in cystic fibrosis and bone marrow transplant patients

Objectives: The aim of the study was to characterise the population pharmacokinetics (popPK) properties of itraconazole (ITRA) and its active metabolite hydroxy-ITRA in a representative paediatric population of cystic fibrosis (CF) and bone marrow transplant (BMT) patients. The goals were to determine the relative bioavailability between the two oral formulations, and to explore improved dosage regimens in these patients. Methods: All paediatric patients with CF taking oral ITRA for the treatment of allergic bronchopulmonary aspergillosis and patients undergoing BMT who were taking ITRA for prophylaxis of any fungal infection were eligible for the study. A minimum of two blood samples were drawn after the capsules and also after switching to oral solution, or vice versa. ITRA and hydroxy-ITRA plasma concentrations were measured by HPLC[1]. A nonlinear mixed-effect modelling approach (NONMEM 5.1.1) was used to describe the PK of ITRA and hydroxy-ITRA simultaneously. Simulations were used to assess dosing strategies in these patients. Results: Forty-nine patients (29CF, 20 BMT) were recruited to the study who provided 227 blood samples for the population analysis. A 1-compartment model with 1st order absorption and elimination best described ITRA kinetics, with 1st order conversion to hydroxy-ITRA. For ITRA, the apparent clearance (ClItra/F) and volume of distribution (Vitra/F) was 35.5L/h and 672L, respectively; the absorption rate constant for the capsule formulation was 0.0901 h-1 and for the oral solution formulation it was 0.959 h-1. The capsule comparative bioavailability (vs. solution) was 0.55. For hydroxy-ITRA, the apparent volume of distribution and clearance were 10.6 L and 5.28 L/h, respectively. Of several screened covariates only allometrically scaled total body weight significantly improved the fit to the data. No difference between the two populations was found. Conclusion: The developed popPK model adequately described the pharmacokinetics of ITRA and hydroxy-ITRA in paediatric patients with CF and patients undergoing BMT. High inter-patient variability confirmed previous data in CF[2], leukaemia and BMT[3] patients. From the population model, simulations showed the standard dose (5 mg/kg/day) needs to be doubled for the solution formulation and even 4 times more given of the capsules to achieve an adequate target therapeutic trough plasma concentration of 0.5 mg/L[4] in these patients.