Electrosynthesis of iminophosphoranes and applications in nickel catalysis

P(v) iminophosphorane compounds are accessed via electrochemical oxidation of commercially available P(iii) phosphines, including mono-, di- and tri-dentate phosphines, as well as chiral phosphines. The reaction uses inexpensive bis(trimethylsilyl)carbodiimide as an efficient and safe aminating reagent. DFT calculations, cyclic voltammetry, and NMR studies provide insight into the reaction mechanism. The proposed mechanism reveals a special case of sequential paired electrolysis. DFT calculations of the frontier orbitals of an iminophosphorane are compared with those of the analogous phosphines and phosphine oxides. X-ray crystallographic studies of the ligands as well as a Ni-coordination complex provide structural insight for these ligands. The utility of these iminophosphoranes as ligands is demonstrated in nickel-catalyzed cross-electrophile couplings including C(sp2)-C(sp3) and C(sp2)-C(sp2) couplings, an electrochemically driven C-N cross-coupling, and a photochemical arylative C(sp3)-H functionalization. In some cases, these new ligands provide improved performance over commonly used sp2-N-based ligands (e.g. 4,4'-di-tert-butyl-2,2'-bipyridine).

Supramolecular Mille-Feuille: Adaptive Guest Inclusion in a New Aliphatic Guanidinium Monosulfonate Hydrogen-Bonded Framework

During the past three decades, the ability of guanidinium arenesulfonate host frameworks to encapsulate a wide range of guests has been amply demonstrated, with more than 700 inclusion compounds realized. Herein, we report crystalline inclusion compounds based on a new aliphatic host, guanidinium cyclohexanemonosulfonate, which surprisingly exhibits four heretofore unobserved architectures, as described by the projection topologies of the organosulfonate residues above and below hydrogen-bonded guanidinium sulfonate sheets. The inclusion compounds adopt a layer motif of guanidinium sulfonate sheets interleaved with guest molecules, resembling a mille-feuille pastry. The aliphatic character of this remarkably simple host, combined with access to greater architectural diversity and adaptability, enables the host framework to accommodate a wide range of guests and promises to expand the utility of guanidinium organosulfonate hosts.

Formation, Selective Encapsulation, and Tautomerization Control of Isoindoleone Utilizing Guanidinium Sulfonate Framework

Herein we report the use of tetrakis(guanidinium) pyrenetetrasulfonate (G4PYR) and bis(guanidinium) 1,5-napthalene disulfonate (G2NDS) to catalyze the cyclization of 2-cyanobenzamide (1) to isoindolone (2). Moreover, we demonstrate the remarkable selectivity of these guanidinium organosulfonate hosts in encapsulating 2 over 1. By thoroughly investigating the intramolecular cyclization reaction, we determined that guanidinium and the organosulfonate moiety acts as the catalyst in this process. Additionally, 2 is selectively encapsulated, even in mixtures of other structurally similar heterocycles like indole. Furthermore, the tautomeric state of 2 (amino isoindolone (2-A) and imino isoindolinone forms (2-I)) can be controlled by utilizing different guanidinium organosulfonate frameworks.

General Synthesis of Conformationally Constrained Noncanonical Amino Acids with C(sp3)-Rich Benzene Bioisosteres

Recent years have seen novel modalities emerge for the treatment of human diseases resulting in an increase in beyond rule of 5 (bRo5) chemical matter. As a result, synthetic innovations aiming to enable rapid access to complex bRo5 molecular entities have become increasingly valuable for medicinal chemists' toolkits. Herein, we report the general synthesis of a new class of noncanonical amino acids (ncAA) with a cyclopropyl backbone to achieve conformational constraint and bearing C(sp3)-rich benzene bioisosteres. We also demonstrate preliminary studies toward utilities of these ncAA as building blocks for medicinal chemistry research.

Fluorinated Isoindolinone-Based Glucosylceramide Synthase Inhibitors with Low Human Dose Projections

Inhibition of glucosylceramide synthase (GCS) has been proposed as a therapeutic strategy for the treatment of Parkinson's Disease (PD), particularly in patients where glycosphingolipid accumulation and lysosomal impairment are thought to be contributing to disease progression. Herein, we report the late-stage optimization of an orally bioavailable and CNS penetrant isoindolinone class of GCS inhibitors. Starting from advanced lead 1, we describe efforts to identify an improved compound with a lower human dose projection, minimal P-glycoprotein (P-gp) efflux, and acceptable pregnane X receptor (PXR) profile through fluorine substitution. Our strategy involved the use of predicted volume ligand efficiency to advance compounds with greater potential for low human doses down our screening funnel. We also applied minimized electrostatic potentials (Vmin) calculations for hydrogen bond acceptor sites to rationalize P-gp SAR. Together, our strategies enabled the alignment of a lower human dose with reduced P-gp efflux, and favorable PXR selectivity for the discovery of compound 12.

From Powders to Single Crystals: A Crystallographer's Toolbox for Small-Molecule Structure Determination

Although the crystal structures of small-molecule compounds are often determined from single-crystal X-ray diffraction (scXRD), recent advances in three-dimensional electron diffraction (3DED) and crystal structure prediction (CSP) methods promise to expand the structure elucidation toolbox available to the crystallographer. Herein, a comparative assessment of scXRD, 3DED, and CSP in combination with powder X-ray diffraction is carried out on two former drug candidate compounds and a multicomponent crystal of a key building block in the synthesis of gefapixant citrate.

Five-Step Enantioselective Synthesis of Islatravir via Asymmetric Ketone Alkynylation and an Ozonolysis Cascade

A 5-step enantioselective synthesis of the potent anti-HIV nucleoside islatravir is reported. The highly efficient route was enabled by a novel enantioselective alkynylation of an α,β-unsaturated ketone, a unique ozonolysis-dealkylation cascade in water, and an enzymatic aldol-glycosylation cascade.

Electrochemical Synthesis of Hindered Primary and Secondary Amines via Proton-Coupled Electron Transfer

Accessing hindered amines, particularly primary amines α to a fully substituted carbon center, is synthetically challenging. We report an electrochemical method to access such hindered amines starting from benchtop-stable iminium salts and cyanoheteroarenes. A wide variety of substituted heterocycles (pyridine, pyrimidine, pyrazine, purine, azaindole) can be utilized in the cross-coupling reaction, including those substituted with a halide, trifluoromethyl, ester, amide, or ether group, a heterocycle, or an unprotected alcohol or alkyne. Mechanistic insight based on DFT data, as well as cyclic voltammetry and NMR spectroscopy, suggests that a proton-coupled electron-transfer mechanism is operational as part of a hetero-biradical cross-coupling of α-amino radicals and radicals derived from cyanoheteroarenes.

Dynamic X-ray diffraction sampling for protein crystal positioning

A sparse supervised learning approach for dynamic sampling (SLADS) is described for dose reduction in diffraction-based protein crystal positioning. Crystal centering is typically a prerequisite for macromolecular diffraction at synchrotron facilities, with X-ray diffraction mapping growing in popularity as a mechanism for localization. In X-ray raster scanning, diffraction is used to identify the crystal positions based on the detection of Bragg-like peaks in the scattering patterns; however, this additional X-ray exposure may result in detectable damage to the crystal prior to data collection. Dynamic sampling, in which preceding measurements inform the next most information-rich location to probe for image reconstruction, significantly reduced the X-ray dose experienced by protein crystals during positioning by diffraction raster scanning. The SLADS algorithm implemented herein is designed for single-pixel measurements and can select a new location to measure. In each step of SLADS, the algorithm selects the pixel, which, when measured, maximizes the expected reduction in distortion given previous measurements. Ground-truth diffraction data were obtained for a 5 µm-diameter beam and SLADS reconstructed the image sampling 31% of the total volume and only 9% of the interior of the crystal greatly reducing the X-ray dosage on the crystal. Using in situ two-photon-excited fluorescence microscopy measurements as a surrogate for diffraction imaging with a 1 µm-diameter beam, the SLADS algorithm enabled image reconstruction from a 7% sampling of the total volume and 12% sampling of the interior of the crystal. When implemented into the beamline at Argonne National Laboratory, without ground-truth images, an acceptable reconstruction was obtained with 3% of the image sampled and approximately 5% of the crystal. The incorporation of SLADS into X-ray diffraction acquisitions has the potential to significantly minimize the impact of X-ray exposure on the crystal by limiting the dose and area exposed for image reconstruction and crystal positioning using data collection hardware present in most macromolecular crystallography end-stations.

Synchrotron X-Ray Diffraction Dynamic Sampling for Protein Crystal Centering

A supervised learning approach for dynamic sampling (SLADS) was developed to reduce X-ray exposure prior to data collection in protein structure determination. Implementation of this algorithm allowed reduction of the X-ray dose to the central core of the crystal by up to 20-fold compared to current raster scanning approaches. This dose reduction corresponds directly to a reduction on X-ray damage to the protein crystals prior to data collection for structure determination. Implementation at a beamline at Argonne National Laboratory suggests promise for the use of the SLADS approach to aid in the analysis of X-ray labile crystals. The potential benefits match a growing need for improvements in automated approaches for microcrystal positioning.

Unified Theory for Polarization Analysis in Second Harmonic and Sum Frequency Microscopy

A unified theoretical framework for the recovery of second-order nonlinear susceptibility tensors and sample orientations from polarization-dependent second harmonic generation and sum frequency generation microscopy was developed. Jones formalism was extended to nonlinear optics and was used to bridge the experimental observables and the local-frame tensor elements. Four commonly used experimental architectures were explicitly explored, including polarization rotation with no postsample optics, polarization-in polarization-out measurement, and polarization modulation with and without postsample optics. Polarization-dependent second harmonic generation measurement was performed on Z-cut quartz and the local-frame tensor elements were calculated. The recovered tensor elements agree with the expected values dictated by symmetry.

Second harmonic generation correlation spectroscopy for characterizing translationally diffusing protein nanocrystals

Second harmonic generation correlation spectroscopy (SHG-CS) is demonstrated as a new approach to protein nanocrystal characterization. A novel line-scanning approach was performed to enable autocorrelation analysis without sample damage from the intense incident beam. An analytical model for autocorrelation was developed, which includes a correction for the optical scattering forces arising when focusing intense, infrared beams. SHG-CS was applied to the analysis of BaTiO3 nanoparticles ranging from 200 to ∼500 nm and of photosystem I nanocrystals. A size distribution was recovered for each sample and compared with the size histogram measured by scanning electron microscopy (SEM). Good agreement was observed between the two independent measurements. The intrinsic selectivity of the second-order nonlinear optical process provides SHG-CS with the ability to distinguish well ordered nanocrystals from conglomerates and amorphous aggregates. Combining the recovered distribution of particle diameters with the histogram of measured SHG intensities provides the inherent hyperpolarizability per unit volume of the SHG-active nanoparticles. Simulations suggest that the SHG activity per unit volume is likely to exhibit relatively low sensitivity to the subtle distortions within the lattice that contribute to resolution loss in X-ray diffraction, but high sensitivity to the presence of multi-domain crystals.

Guiding synchrotron X-ray diffraction by multimodal video-rate protein crystal imaging

Synchronous digitization, in which an optical sensor is probed synchronously with the firing of an ultrafast laser, was integrated into an optical imaging station for macromolecular crystal positioning prior to synchrotron X-ray diffraction. Using the synchronous digitization instrument, second-harmonic generation, two-photon-excited fluorescence and bright field by laser transmittance were all acquired simultaneously with perfect image registry at up to video-rate (15 frames s(-1)). A simple change in the incident wavelength enabled simultaneous imaging by two-photon-excited ultraviolet fluorescence, one-photon-excited visible fluorescence and laser transmittance. Development of an analytical model for the signal-to-noise enhancement afforded by synchronous digitization suggests a 15.6-fold improvement over previous photon-counting techniques. This improvement in turn allowed acquisition on nearly an order of magnitude more pixels than the preceding generation of instrumentation and reductions of well over an order of magnitude in image acquisition times. These improvements have allowed detection of protein crystals on the order of 1 µm in thickness under cryogenic conditions in the beamline. These capabilities are well suited to support serial crystallography of crystals approaching 1 µm or less in dimension.

Parts per Million Powder X-ray Diffraction

Here we demonstrate the use of second harmonic generation (SHG) microscopy-guided synchrotron powder X-ray diffraction (PXRD) for the detection of trace crystalline active pharmaceutical ingredients in a common polymer blend. The combined instrument is capable of detecting 100 ppm crystalline ritonavir in an amorphous hydroxypropyl methylcellulose matrix with a high signal-to-noise ratio (>5000). The high spatial resolution afforded by SHG microscopy allows for the use of a minibeam collimator to reduce the total volume of material probed by synchrotron PXRD. The reduction in probed volume results in reduced background from amorphous material. The ability to detect low crystalline loading has the potential to improve measurements in the formulation pipeline for pharmaceutical solid dispersions, for which even trace quantities of crystalline active ingredients can negatively impact the stability and bioavailability of the final drug product.

Intercalating dyes for enhanced contrast in second-harmonic generation imaging of protein crystals

The second-harmonic generation (SHG) activity of protein crystals was found to be enhanced by up to ∼1000-fold by the intercalation of SHG phores within the crystal lattice. Unlike the intercalation of fluorophores, the SHG phores produced no significant background SHG from solvated dye or from dye intercalated into amorphous aggregates. The polarization-dependent SHG is consistent with the chromophores adopting the symmetry of the crystal lattice. In addition, the degree of enhancement for different symmetries of dyes is consistent with theoretical predictions based on the molecular nonlinear optical response. Kinetics studies indicate that intercalation arises over a timeframe of several minutes in lysozyme, with detectable enhancements within seconds. These results provide a potential means to increase the overall diversity of protein crystals and crystal sizes amenable to characterization by SHG microscopy.

Multi-channel beam-scanning imaging at kHz frame rates by Lissajous trajectory microscopy

A beam-scanning microscope based on Lissajous trajectory imaging is described for achieving streaming 2D imaging with continuous frame rates up to 1.4 kHz. The microscope utilizes two fast-scan resonant mirrors to direct the optical beam on a circuitous trajectory through the field of view. By separating the full Lissajous trajectory time-domain data into sub-trajectories (partial, undersampled trajectories) effective frame-rates much higher than the repeat time of the Lissajous trajectory are achieved with many unsampled pixels present. A model-based image reconstruction (MBIR) 3D in-painting algorithm is then used to interpolate the missing data for the unsampled pixels to recover full images. The MBIR algorithm uses a maximum a posteriori estimation with a generalized Gaussian Markov random field prior model for image interpolation. Because images are acquired using photomultiplier tubes or photodiodes, parallelization for multi-channel imaging is straightforward. Preliminary results show that when combined with the MBIR in-painting algorithm, this technique has the ability to generate kHz frame rate images across 6 total dimensions of space, time, and polarization for SHG, TPEF, and confocal reflective birefringence data on a multimodal imaging platform for biomedical imaging. The use of a multi-channel data acquisition card allows for multimodal imaging with perfect image overlay. Image blur due to sample motion was also reduced by using higher frame rates.

High frame-rate multichannel beam-scanning microscopy based on Lissajous trajectories

A simple beam-scanning optical design based on Lissajous trajectory imaging is described for achieving up to kHz frame-rate optical imaging on multiple simultaneous data acquisition channels. In brief, two fast-scan resonant mirrors direct the optical beam on a circuitous trajectory through the field of view, with the trajectory repeat-time given by the least common multiplier of the mirror periods. Dicing the raw time-domain data into sub-trajectories combined with model-based image reconstruction (MBIR) 3D in-painting algorithms allows for effective frame-rates much higher than the repeat time of the Lissajous trajectory. Since sub-trajectory and full-trajectory imaging are simply different methods of analyzing the same data, both high-frame rate images with relatively low resolution and low frame rate images with high resolution are simultaneously acquired. The optical hardware required to perform Lissajous imaging represents only a minor modification to established beam-scanning hardware, combined with additional control and data acquisition electronics. Preliminary studies based on laser transmittance imaging and polarization-dependent second harmonic generation microscopy support the viability of the approach both for detection of subtle changes in large signals and for trace-light detection of transient fluctuations.

Characterization of salt interferences in second-harmonic generation detection of protein crystals

Studies were undertaken to assess the merits and limitations of second-harmonic generation (SHG) for the selective detection of protein and polypeptide crystal formation, focusing on the potential for false positives from SHG-active salts present in crystallization media. The SHG activities of salts commonly used in protein crystallization were measured and quantitatively compared with reference samples. Out of 19 salts investigated, six produced significant background SHG and 15 of the 96 wells of a sparse-matrix screen produced SHG upon solvent evaporation. SHG-active salts include phosphates, hydrated sulfates, formates and tartrates, while chlorides, acetates and anhydrous sulfates resulted in no detectable SHG activity. The identified SHG-active salts produced a range of signal intensities spanning nearly three orders of magnitude. However, even the weakest SHG-active salt produced signals that were several orders of magnitude greater than those produced by typical protein crystals. In general, SHG-active salts were identifiable through characteristically strong SHG and negligible two-photon-excited ultraviolet fluorescence (TPE-UVF). Exceptions included trials containing either potassium dihydrogen phosphate or ammonium formate, which produced particularly strong SHG, but with residual weak TPE-UVF signals that could potentially complicate discrimination in crystallization experiments using these precipitants.

Integrated nonlinear optical imaging microscope for on-axis crystal detection and centering at a synchrotron beamline

Nonlinear optical (NLO) instrumentation has been integrated with synchrotron X-ray diffraction (XRD) for combined single-platform analysis, initially targeting applications for automated crystal centering. Second-harmonic-generation microscopy and two-photon-excited ultraviolet fluorescence microscopy were evaluated for crystal detection and assessed by X-ray raster scanning. Two optical designs were constructed and characterized; one positioned downstream of the sample and one integrated into the upstream optical path of the diffractometer. Both instruments enabled protein crystal identification with integration times between 80 and 150 µs per pixel, representing a ∼10(3)-10(4)-fold reduction in the per-pixel exposure time relative to X-ray raster scanning. Quantitative centering and analysis of phenylalanine hydroxylase from Chromobacterium violaceum cPAH, Trichinella spiralis deubiquitinating enzyme TsUCH37, human κ-opioid receptor complex kOR-T4L produced in lipidic cubic phase (LCP), intimin prepared in LCP, and α-cellulose samples were performed by collecting multiple NLO images. The crystalline samples were characterized by single-crystal diffraction patterns, while α-cellulose was characterized by fiber diffraction. Good agreement was observed between the sample positions identified by NLO and XRD raster measurements for all samples studied.

Fourier magnitude of the field incident on a random scattering medium from spatial speckle intensity correlations

Spatial speckle intensity correlations are used to determine the spatial Fourier magnitude of a field incident on a random scattering medium. The patterned beam is scanned across the scattering medium, and the speckle pattern on the opposite side is imaged at each beam position. A theory based on a Green's function representation is used to reconstruct the spatial Fourier magnitude of the patterned incident field.

Verification of biomechanical methods employed in a comprehensive study of mild traumatic brain injury and the effectiveness of American football helmets

Concussion, or mild traumatic brain injury, occurs in many activities, mostly as a result of the head being accelerated. A comprehensive study has been conducted to understand better the mechanics of the impacts associated with concussion in American football. This study involves a sequence of techniques to analyse and reconstruct many different head impact scenarios. It is important to understand the validity and accuracy of these techniques in order to be able to use the results of the study to improve helmets and helmet standards. Two major categories of potential errors have been investigated. The first category concerns error sources specific to the use of crash test dummy instrumentation (accelerometers) and associated data processing techniques. These are relied upon to establish both linear and angular head acceleration responses. The second category concerns the use of broadcast video data and crash test dummy head-neck-torso systems. These are used to replicate the complex head impact scenarios of whole body collisions that occur on the football field between two living human beings. All acceleration measurement and processing techniques were based on well-established practices and standards. These proved to be reliable and reproducible. Potential errors in the linear accelerations due to electrical or mechanical noise did not exceed 2% for the three different noise sources investigated. Potential errors in the angular accelerations due to noise could be as high as 6.7%, due to error accumulation of multiple linear acceleration measurements. The potential error in the relative impact velocity between colliding heads could be as high as 11%, and was found to be the largest error source in the sequence of techniques to reconstruct the game impacts. Full-scale experiments with complete crash test dummies in staged head impacts showed maximum errors of 17% for resultant linear accelerations and 25% for resultant angular accelerations.

A proposed new biomechanical head injury assessment function - the maximum power index

Recently, several cases of mild traumatic brain injury to American professional football players have been reconstructed using instrumented Hybrid III anthropomorphic test dummies ATDs. The translational and rotational acceleration responses of injured and uninjured players' heads have been documented. The acceleration data have been processed according to all current head injury assessment functions including the GSI, HIC and GAMBIT among others. A new hypothesis is propounded that the threshold for head injury will be exceeded if the rate of change of kinetic energy of the head exceeds some limiting value. A functional relation is proposed, which includes all six degrees of motion and directional sensitivity characteristics, relating the rate of change of kinetic energy to the probability of head injury. The maximum value that the function achieves during impact is the maximum power input to the head and serves as an index by which the probability of head injury can be assessed.

Measuring the Cosmic Equation of State with Counts of Galaxies

The classical dN/dz test allows one to determine fundamental cosmological parameters from the evolution of the cosmic volume element. This test is applied by measuring the redshift distribution of a tracer whose evolution in number density is known. In the past, ordinary galaxies have been used for this; however, in the absence of a complete theory of galaxy formation, that method is fraught with difficulties. In this Letter, we propose studying instead the evolution of the apparent numbers of dark matter halos as a function of their circular velocity, observable via the line widths or rotation speeds of visible galaxies. Upcoming redshift surveys will allow the line width distribution of galaxies to be determined at both z approximately 1 and the present day. In the course of studying this test, we have devised a rapid, improved semianalytic method for calculating the circular velocity distribution of dark halos based on the analytic mass function of Sheth, Mo, & Tormen and the formation time distribution of Lacey & Cole. We find that if selection effects are well controlled and minimal external constraints are applied, the planned DEEP Redshift Survey could allow us to measure the cosmic equation-of-state parameter w to +/-10% (as little as 3% if Omegam has been well determined from other observations). This type of test also has the potential to provide a constraint on any evolution of w, such as that predicted by "tracker" models.

A distance to the galaxy NGC4258 from observations of Cepheid variable stars

Cepheid variable stars pulsate in a way that is correlated with their intrinsic luminosity, making them useful as 'standard candles' for determining distances to galaxies; the potential systematic uncertainties in the resulting distances have been estimated to be only 8-10%. They have played a crucial role in establishing the extragalactic distance scale and hence the value of the Hubble constant. Here we report observations of Cepheids in the nearby galaxy NGC4258; the distance calculated from the Cepheids is 8.1 +/- 0.4 Mpc, where the uncertainty does not include possible systematic errors. There is an independently determined geometric distance to this galaxy of 7.2 +/- 0.5 Mpc, based on the observed proper motions of water masers orbiting the central black hole; the distances differ by 1.3sigma. If the maser-based distance is adopted and the Cepheid distance scale revised accordingly, the derived value of the Hubble constant would increase by 12 +/- 9%, while the expansion age of the Universe would decrease by the same amount.

Identification of Mycoplasma iowae by colony immunoblotting utilizing monoclonal antibodies

The utility of monoclonal antibody Mab-2C in identification of Mycoplasma iowae (MI) by colony immunoblotting technique was explored. Colony immunoblots of reference MI strains, field isolates, and mycoplasmas recovered from experimentally inoculated turkey embryos were probed with Mab-2C. The monoclonal antibody identified colonies of all the MI isolates tested and did not cross-react with colonies of M. gallisepticum, M. synoviae, or M. meleagridis. In western immunoblots of 22 MI field isolates, Mab-2C showed immunoreactivity with an antigen of approximately 45 kD molecular weight. No phenotypic variation of the epitope recognized by Mab-2C was observed in colony immunoblots of MI colonies. The monoclonal antibody reported here can be used for identification of MI colonies by a simple and rapid colony immunoblot method.

Monoclonal antibodies specific to Mycoplasma iowae

Monoclonal antibodies (MAbs) against Mycoplasma iowae (MI) were produced to identify common immunogenic determinants shared between antigenically heterogenous MI. Twenty-four MAbs were produced against MI. With western immunoblotting, all 24 MAbs recognized a 45,000-MW protein (p45) of MI strain I-695. One of the MAbs characterized, MAb 2C, identified p45 antigen in western immunoblots with six laboratory strains and 24 field isolates of MI. MAb 2C did not cross-react with Mycoplasma gallisepticum, Mycoplasma synoviae, Mycoplasma meleagridis, or nonpathogenic avian mycoplasmas. Triton X-114 phase separation of MI proteins showed that p45 is an integral membrane protein. In immunofluorescent staining and immunoelectron microscopy of MI, MAb 2C reacted with surface antigen(s). These MAbs specific to MI may be used in detection and diagnosis of MI infections.

Least-squares estimation of diet composition from n-alkanes in herbage and faeces using matrix mathematics

It is possible to estimate diet composition from an analysis of n-alkanes in the faeces of ruminant animals. For instance, to estimate the proportion of two species in a diet, two equations are constructed using the known concentrations of two different n-alkanes in the herbage and in the animal's faeces. These two equations are solved for the two unknown quantities of the diet components. Two problems exist with this method. First, it is often the case that we have estimated concentrations of more than two different n-alkanes. This can lead to a problem in deciding which two n-alkanes to use to construct the simultaneous equations. The choice of this pair of n-alkanes is arbitrary in its selection and wasteful of other useful information. The second problem is that sometimes the solution to the simultaneous equations yields nonsensical answers, such as a negative proportion of one species in the diet. In addition to making it difficult to estimate dietary proportions, estimating digestibility becomes impossible. In this paper, we present a technique which provides an estimate of the dietary proportions. This estimate uses information on all the n-alkanes available, and it has a very desirable property of being a least squares estimate. We also present a method for determining the least squares estimate subject to the constraint that all proportions must be non-negative. We provide examples for estimating the proportions of grass and clover in the diet of sheep and the digestibility of those diets.

Toward a comprehensive biomechanical injury cost model

The proposed biomechanical injury cost model utilizes surrogate-based injury assessment functions to predict the probability of occurrence and the probable cost of specific injuries to the head, thorax, abdomen, and lower extremities. The resulting probability cost is a function of the number, location, and severity of injuries. As more precise injury assessment functions and more accurate cost estimates become available, the model will become an effective tool for comparing and classifying different injury patterns.

Effect of temperature on the stability of avian influenza virus antigens under different storage conditions

The combined effect of time and temperature on the stability of two avian influenza virus (AIV) isolates concentrated with polyethylene glycol (PEG), stored at different temperatures, and used in the preparation of avian influenza vaccine was evaluated in turkeys at 24 hr and at 12, 24, 30, 36, and 42 months of storage. The differences detected between antibodies raised in turkeys by vaccines made from isolates under different storage conditions, times, and temperatures were not significant (P > 0.05), especially with vaccines prepared from one isolate. Virus recovery rates following challenge studies of vaccinated birds were similar. However, birds that were vaccinated twice had lower rates of virus recovery from the trachea, lungs, pancreas, and fecal samples following challenge infection. The results suggest that if stable isolates of AIV can be identified, such isolates can be rapidly concentrated with PEG and stored at -20 C or -196 C for at least 42 months without any loss of potency in the vaccine prepared from these isolates. This would reduce the costs associated with vaccine storage and subsequent expiration dates.

Description of osteomyelitis lesions associated with Actinomyces pyogenes infection in the proximal tibia of adult male turkeys

Actinomyces pyogenes was isolated from osteomyelitis lesions from the proximal tibia of mature tom turkeys. Gram-stained impression smears of the lesions resulted in bacteria that appeared as club-shaped, gram-positive pleomorphic rods. The bacteria grew better in a reduced-oxygen environment. The lesions were well demarcated and cavernous, ranging from purulent to caseous in consistency.

Virulence factors of Escherichia coli associated with colisepticemia in chickens and turkeys

Four hundred twenty turkey and 80 chicken Escherichia coli isolates from colisepticemic birds were examined for the following properties: heat-labile toxin (LT), heat-stable enterotoxin, verotoxin, colicinogenicity, hemolysin, and hydroxamate/aerobactin production. Twenty-four (5.7%) of the 420 turkey isolates and six (7.5%) of the 80 chicken isolates produced an LT that was cytotoxic for both Vero and Y-1 cells. In contrast, 48 (11.4%) of the turkey isolates and 18 (22.5%) of the chicken isolates produced a distinct LT that was cytotoxic only for Vero cells. In addition, 64 (80.0%) of the chicken isolates and 309 (74.0%) of the turkey isolates produced aerobactin. Colicinogenicity occurred in 51 (64.0%) of the chicken isolates, with 41 (51.0%) producing colicin V. By contrast, 254 (61.0%) of the turkey isolates produced a colicin, of which 176 (42.0%) produced colicin V. None of the chicken and turkey isolates produced hemolysin or heat-stable enterotoxin.

Enhancement of antibody response of turkeys to trivalent avian influenza vaccine by positively charged liposomal avridine adjuvant

Trivalent avian influenza (AIV) antigens (H4N8, H5N2 and H7N3), mixed with positively charged, negatively charged and neutral avridine-containing liposomes, and oil-emulsion were subcutaneously administered to 6-week-old turkeys. Charged liposomal avridine adjuvant, either positive or negative, produced a better antibody response than uncharged liposomal avridine or oil-emulsion adjuvants when used in a trivalent avian influenza vaccine. The antibody response to the different antigens was generally greater to the positively charged adjuvanted vaccine compared with the negatively or neutral charged or oil-emulsion adjuvanted vaccines and these differences were significant (P less than 0.05) with the three antigens. The results suggest that the positively charged liposomal avridine plays a significant role as adjuvant to the AIV antigens.

A quantitative measurement of the effect of avian influenza virus on the ability of turkeys to eliminate Pasteurella multocida from the respiratory tract

The effect of avian influenza virus (AIV) infection on the ability of turkeys to eliminate Pasteurella multocida from the respiratory tract was evaluated. Four-week-old turkeys were experimentally infected with an apathogenic AIV subtype (H5N2) by the oculonasal route and subsequently superinfected with P multocida (Urbach strain) by the intranasal route three days after infection with AIV. Quantitative clearance of P multocida from the trachea and lung was determined using a pour plate technique on samples collected at intervals after infection. Samples from turkeys which had been infected with AIV were found to yield more P multocida than those from turkeys which had not been infected with AIV. The numbers of P multocida increased in infected birds to a greater extent than in birds which had not been infected with the virus. The present study suggests that AIV infection may contribute to the increased numbers and a decreased clearance of P multocida in turkeys.

Endotoxin lipopolysaccharide from Escherichia coli and its effects on the phagocytic function of systemic and pulmonary macrophages in turkeys

The effect of Escherichia coli lipopolysaccharide (LPS) on the competence of pulmonary macrophages and phagocytic cells from the systemic circulation of turkeys was examined using luminol-enhanced zymosan-stimulated chemiluminescence. The results showed a rapid and accelerated oxidative burst in both systemic and pulmonary macrophages in LPS-treated turkeys that was significantly greater than in untreated controls. However, this increased oxidative metabolism induced by LPS was not associated with enhanced intracellular bacterial killing by pulmonary macrophages. Turkeys treated with LPS showed a highly significant decrease in pulmonary bactericidal activity against Staphylococcus aureus challenge, indicating a defect in pulmonary macrophage function induced by LPS.

Serological response in broiler chicks to different commercial Newcastle disease and infectious bronchitis vaccines

Broiler chicks were administered vaccines against Newcastle disease and infectious bronchitis (both Arkansas and Massachusetts strains) at 2 weeks of age as either primary or secondary vaccinations. The vaccine was administered as a spray at 2 weeks of age to chicks that had received Newcastle disease vaccine alone, bronchitis vaccine alone, both vaccines in combination, or no vaccine at day 1 in the hatchery. The Newcastle disease hemagglutination-inhibition response was significantly lower in chicks receiving Newcastle disease vaccine as a secondary vaccine at 2 weeks than in those receiving the vaccine as a primary vaccination at that age. In contrast, the bronchitis hemagglutination-inhibition response was significantly higher in chicks receiving bronchitis vaccine as a secondary vaccination at 2 weeks than in those receiving the vaccine as a primary vaccination at that age.

Identification and characterization of viral polypeptides from type-II avian adenoviruses

The polypeptides of serologically related viruses of hemorrhagic enteritis (HE) in turkeys, marble spleen disease (MSD) in pheasants, and splenomegaly in chickens (SMC) were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and analyzed by protein immunoblotting with polyclonal antibodies to HE virus (HEV). The viral polypeptides II, III, IV, V, VI, and VII were detected on SDS-PAGE with the size range from 18 to 97 kDa in HEV. Viral polypeptides II, III, V, VI, and VII were detected in MSD virus and virus of SMC. Protein immunoblotting of viral proteins with anti-HEV serum revealed antigenic differences between the 3 viruses of avian adenovirus type-II examined. The differences were that the polypeptides II, III, IV, V, VI, and VII were identified in HEV and the polypeptides II, V, VI, and VII were identified in MSD virus and virus of SMC. The bands of penton base (polypeptide III) and fiber (polypeptide IV) were seen in HEV only by protein immunoblotting.

Key issues in mergers and acquisitions. Healthcare organizations must approach collaborations with caution

Most collaborations between healthcare providers are based on a desire to better serve their communities, develop critical mass, eliminate duplicative services, create economies of scale, and enhance survivability. Unfortunately, collaborations may not always produce the benefits desired. Thus careful planning and execution are critical to first determine whether the transaction makes sense and, if it does, to develop strategies that maximize the expected benefits. Whether the participating entities are secular, religious, public, or private, I recommend they consider the following 11 key issues when evaluating or pursuing a merger or acquisition: (1) understand the transaction's magnitude, (2) assess the alternatives, (3) select potential partners carefully, (4) determine and examine threshold issues early, (5) focus on the right issues, (6) agree on a valuation approach, (7) recognize the importance of governance, (8) develop an acceptable structure, and use a memorandum of understanding, (9) establish and adhere to a communications policy, (10) perform due diligence, and (11) recognize the significance of activities after the transaction.

Perirenal hemorrhage syndrome in market turkey toms: effect of management factors

Differences in the overall mortality rates and mortality due to perirenal hemorrhage syndrome (PHS) were compared in large white Nicholas tom turkeys. The study evaluated the effects of 1) four different light and temperature treatments; 2) three feed additives proposed to have anti-stress effects (reserpine, acetylsalicylic acid, and increased calcium); 3) toe-clipping on mortality, various disease conditions, and production parameters. Mortality varied from 0.60% to 3.57% among groups. Increased room temperature (21 C), toe-clipping, step-up/step-down lighting, and dietary reserpine reduced the incidence of PHS as compared with lower room temperature (13 C), no toe-clipping, intermittent lighting (2 hours light, 4 hours dark), and no dietary reserpine. Dietary aspirin or elevated calcium levels had no effect on PHS incidence. Overall mortality was greatest in the warmer rooms.

The incidence of perirenal hemorrhage syndrome in six flocks of market turkey toms

Four flocks of the Nicholas strain and two of the British United turkey (BUT) strain of large white market turkey toms were monitored from 8 to 19 weeks of age to identify the presence, incidence, age distribution, and possible cause(s) of perirenal hemorrhage syndrome (PHS), or acute hypertensive angiopathy. Mortality rates varied among the flocks from 0.81% to 1.78% of total poults started. Nicholas flocks has a distinct peak in mortality between 9 and 14 weeks of age. PHS was the main cause of mortality from 8 to 14 weeks of age in all flocks except one, and the incidence diminished after 15 weeks of age. No significant bacterial pathogens were detected in any of the PHS cases. Distinct peaks in overall weekly mortality between 10 and 13 weeks of age similar to those in the four Nicholas flocks were also observed in six of 10 Minnesota flocks surveyed separately.

Preliminary data on efficacy of Mycoplasma gallisepticum vaccines containing different adjuvants in laying hens

Chickens were vaccinated subcutaneously twice, at 13 and 17 weeks of age. The vaccines used were the whole organisms of Mycoplasma gallisepticum (MG) adjuvanted with multilamellar positively charged (MPC) liposomes or oil-emulsion. Other chickens received the same bacterins but supplemented with Salmonella typhimurium cell wall protein mitogen (STP) (50 micrograms/dose). At 21 weeks of age, each bird was challenged in the right and left caudal thoracic air sacs. The challenge dose/chicken was 1.3 x 10(5) CFU of MG (R-strain). A significant immunoglobulin (Ig) response specific to MG was observed in sera of chickens collected 3 weeks after the first and second vaccination with MG adjuvanted with MPC liposomes or oil-emulsion. The same two treatments had highly significant MG-titers in eggs collected during the first and second month post challenge. Both groups had highly significant protection (P less than 0.05) against MG transmission in eggs layed during the first month post challenge. Vaccination with MG organisms adjuvanted to MPC liposomes or oil-emulsion resulted in higher egg production, during the first month following challenge, in comparison to the unvaccinated-challenged birds; the same two groups had higher egg production in the second month following challenge compared to unvaccinated-challenged birds, but not significantly different (P greater than 0.05). The addition of STP to bacterins containing MG organisms adjuvanted to MPC liposomes or oil-emulsion, resulted in a significant reduction (P less than 0.05) of the Ig-specific to MG in sera and in a significant drop in egg production (P less than 0.05) during the first month following challenge.

Identification of the antigenic components of paramyxovirus-3, paramyxovirus-6 and Newcastle disease virus in turkeys

The aim of this study was to use the enzyme-linked immunosorbent assay (ELISA) and the Western immunoblotting as possible tools to differentiate infections in turkeys by different paramyxoviruses. Pooled hyperimmune sera of turkeys infected with either paramyxovirus-3 (PMV-3), paramyxovirus-6 (PMV-6), or Newcastle disease virus (NDV) were assayed for antibodies specific to the three viruses by the ELISA and Western immunoblotting. ELISA results showed cross reactions of turkey antibodies between PMV-3 and PMV-6 antigens, while turkey antibodies to NDV did not cross-react with any of the other paramyxoviruses. The immunoblots of sera from birds infected with PMV-3 (Minnesota turkeys and Iowa chickens) reacted to low molecular weight polypeptides of PMV-3 of 29, 32, and 34 kDa, and to a high molecular weight band of 200 kDa. The same Minnesota turkey sera had a cross reaction to the 200 kDa polypeptide of PMV-6, while the Iowa chicken sera did not. Both sera had no apparent reaction to NDV proteins. Western immunoblotting showed that the turkey PMV-3 sera had a specific reaction to a 220 kDa polypeptide present in PMV-3, but not in PMV-6, while the turkey PMV-6 sera had a specific reaction to a 130 kDa polypeptide present in PMV-6, but not in PMV-3. Immunoblots of pooled sera from turkeys infected with PMV-6 (Minnesota source) reacted to the 200 kDa protein present in both PMV-3 and PMV-6; however, no reaction occurred between this sera and NDV proteins.(ABSTRACT TRUNCATED AT 250 WORDS)