Topographic Control of Order in Quasi-2D Granular Phase Transitions

We experimentally investigate the nature of 2D phase transitions in a quasi-2D granular fluid. Using a surface decorated with periodically spaced dimples we observe interfacial tension between coexisting granular liquid and crystal phases. Measurements of the orientational and translational order parameters and associated susceptibilities indicate that the surface topography alters the order of the phase transition from a two-step continuous one to a first-order liquid-solid one. The interplay of boundary inelasticity and geometry, either order promoting or inhibiting, controls whether it is the granular crystal or the granular fluid which makes contact with the edge. This order induced wetting has important consequences, determining how coexisting phases separate spatially.

Collision-enhanced friction of a bouncing ball on a rough vibrating surface

We describe experiments and simulations to investigate the dynamics of a ball bouncing on a rough vibrating surface. Directly measuring the impulse due to each bounce we find that the frictional interaction with the surface is strongly enhanced near to the side wall. The enhanced dissipation arises as a consequence of the coupling between the collision, rotation and surface friction. This dissipation, which for our experimental conditions was estimated to be up to three times larger than the more obvious inelastic collision, can result in an enhanced probability density near boundaries and particle–particle spatial correlations. Our findings imply that the effective particle collision properties cannot be considered independently of the surface’s frictional properties.

The serine protease testisin is present on the surface of capacitated stallion spermatozoa and interacts with key zona pellucida binding proteins

BACKGROUND AND OBJECTIVES

Serine proteases are emerging as important players in the spermatozoon's acquisition of functional competence. This study aimed to characterize the serine protease testisin (PRSS21) in stallion spermatozoa, examining its surface expression, possible origins in the testis and epididymis, and changes in response to capacitation and acrosome reaction, as well as its capacity to form high molecular weight complexes and interact with other proteins.

MATERIALS AND METHODS

The role of serine proteases in spontaneous capacitation and acrosome reaction of stallion spermatozoa was established using the serine protease inhibitor, AEBSF. Testisin localization, before and after exposure of stallion spermatozoa to capacitating conditions and calcium ionophore, was examined using live cell immunofluorescence and flow cytometry. Immunohistochemistry of testicular and epididymal tissues was used to further dissect the origins of sperm testisin. Testisin's participation in high molecular weight protein complexes and identification of its interacting partner proteins were investigated using Blue Native PAGE, co-immunoprecipitation, and mass spectrometry, with interrogation of protein-protein interaction databases and gene ontology analysis of partner proteins used to further explore the potential roles of the testisin-containing complex in sperm function.

RESULTS

Testisin surface expression increased significantly in capacitated spermatozoa (p < 0.001), increased further following acrosome reaction (p < 0.01), and was localized to the equatorial region of the sperm head. Testisin was also detected in luminal fluid within the caput and corpus regions of the epididymis, epididymal spermatozoa, and epididymal epithelial cells. Testisin formed several multiprotein complexes; co-immunoprecipitation revealed interactions of testisin with a multitude of zona pellucida-binding proteins, including ZPBP, ZAN, acrosin, several heat-shock proteins, and components of the TCP1 complex.

CONCLUSION

Testisin appears to form part of the zona pellucida-binding complex in stallion spermatozoa and may be involved in the proteolytic cascade that prepares the sperm surface for interaction with the oocyte.

Boundary effects in a quasi-two-dimensional driven granular fluid

The effect of a confining boundary on the spatial variations in granular temperature of a driven quasi-two-dimensional layer of particles is investigated experimentally. The radial drop in the relative granular temperature ΔT/T exhibits a maximum at intermediate particle numbers which coincides with a crossover from kinetic to collisional transport of energy. It is also found that at low particle numbers, the distributions of radial velocities are increasingly asymmetric as one approaches the boundary. The radial and tangential granular temperatures split, and in the tails of the radial velocity distribution there is a higher population of fast moving particles traveling away rather than towards the boundary.

Characterization of transient noise in Advanced LIGO relevant to gravitational wave signal GW150914

On September 14, 2015, a gravitational wave signal from a coalescing black hole binary system was observed by the Advanced LIGO detectors. This paper describes the transient noise backgrounds used to determine the significance of the event (designated GW150914) and presents the results of investigations into potential correlated or uncorrelated sources of transient noise in the detectors around the time of the event. The detectors were operating nominally at the time of GW150914. We have ruled out environmental influences and non-Gaussian instrument noise at either LIGO detector as the cause of the observed gravitational wave signal.

GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence

We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, and reached a peak gravitational strain of 3.4_{-0.9}^{+0.7}×10^{-22}. The inferred source-frame initial black hole masses are 14.2_{-3.7}^{+8.3}M_{⊙} and 7.5_{-2.3}^{+2.3}M_{⊙}, and the final black hole mass is 20.8_{-1.7}^{+6.1}M_{⊙}. We find that at least one of the component black holes has spin greater than 0.2. This source is located at a luminosity distance of 440_{-190}^{+180}  Mpc corresponding to a redshift of 0.09_{-0.04}^{+0.03}. All uncertainties define a 90% credible interval. This second gravitational-wave observation provides improved constraints on stellar populations and on deviations from general relativity.

Properties of the Binary Black Hole Merger GW150914

On September 14, 2015, the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected a gravitational-wave transient (GW150914); we characterize the properties of the source and its parameters. The data around the time of the event were analyzed coherently across the LIGO network using a suite of accurate waveform models that describe gravitational waves from a compact binary system in general relativity. GW150914 was produced by a nearly equal mass binary black hole of masses 36_{-4}^{+5}M_{⊙} and 29_{-4}^{+4}M_{⊙}; for each parameter we report the median value and the range of the 90% credible interval. The dimensionless spin magnitude of the more massive black hole is bound to be <0.7 (at 90% probability). The luminosity distance to the source is 410_{-180}^{+160}  Mpc, corresponding to a redshift 0.09_{-0.04}^{+0.03} assuming standard cosmology. The source location is constrained to an annulus section of 610  deg^{2}, primarily in the southern hemisphere. The binary merges into a black hole of mass 62_{-4}^{+4}M_{⊙} and spin 0.67_{-0.07}^{+0.05}. This black hole is significantly more massive than any other inferred from electromagnetic observations in the stellar-mass regime.

GW150914: First results from the search for binary black hole coalescence with Advanced LIGO

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) simultaneously observed the binary black hole merger GW150914. We report the results of a matched-filter search using relativistic models of compact-object binaries that recovered GW150914 as the most significant event during the coincident observations between the two LIGO detectors from September 12 to October 20, 2015. GW150914 was observed with a matched filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203000 years, equivalent to a significance greater than 5.1 σ.

GW150914: First results from the search for binary black hole coalescence with Advanced LIGO

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) simultaneously observed the binary black hole merger GW150914. We report the results of a matched-filter search using relativistic models of compact-object binaries that recovered GW150914 as the most significant event during the coincident observations between the two LIGO detectors from September 12 to October 20, 2015. GW150914 was observed with a matched filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203000 years, equivalent to a significance greater than 5.1 σ.

Tests of General Relativity with GW150914

The LIGO detection of GW150914 provides an unprecedented opportunity to study the two-body motion of a compact-object binary in the large-velocity, highly nonlinear regime, and to witness the final merger of the binary and the excitation of uniquely relativistic modes of the gravitational field. We carry out several investigations to determine whether GW150914 is consistent with a binary black-hole merger in general relativity. We find that the final remnant's mass and spin, as determined from the low-frequency (inspiral) and high-frequency (postinspiral) phases of the signal, are mutually consistent with the binary black-hole solution in general relativity. Furthermore, the data following the peak of GW150914 are consistent with the least-damped quasinormal mode inferred from the mass and spin of the remnant black hole. By using waveform models that allow for parametrized general-relativity violations during the inspiral and merger phases, we perform quantitative tests on the gravitational-wave phase in the dynamical regime and we determine the first empirical bounds on several high-order post-Newtonian coefficients. We constrain the graviton Compton wavelength, assuming that gravitons are dispersed in vacuum in the same way as particles with mass, obtaining a 90%-confidence lower bound of 10^{13}  km. In conclusion, within our statistical uncertainties, we find no evidence for violations of general relativity in the genuinely strong-field regime of gravity.

GW150914: Implications for the Stochastic Gravitational-Wave Background from Binary Black Holes

The LIGO detection of the gravitational wave transient GW150914, from the inspiral and merger of two black holes with masses ≳30M_{⊙}, suggests a population of binary black holes with relatively high mass. This observation implies that the stochastic gravitational-wave background from binary black holes, created from the incoherent superposition of all the merging binaries in the Universe, could be higher than previously expected. Using the properties of GW150914, we estimate the energy density of such a background from binary black holes. In the most sensitive part of the Advanced LIGO and Advanced Virgo band for stochastic backgrounds (near 25 Hz), we predict Ω_{GW}(f=25  Hz)=1.1_{-0.9}^{+2.7}×10^{-9} with 90% confidence. This prediction is robustly demonstrated for a variety of formation scenarios with different parameters. The differences between models are small compared to the statistical uncertainty arising from the currently poorly constrained local coalescence rate. We conclude that this background is potentially measurable by the Advanced LIGO and Advanced Virgo detectors operating at their projected final sensitivity.

GW150914: The Advanced LIGO Detectors in the Era of First Discoveries

Following a major upgrade, the two advanced detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) held their first observation run between September 2015 and January 2016. With a strain sensitivity of 10^{-23}/sqrt[Hz] at 100 Hz, the product of observable volume and measurement time exceeded that of all previous runs within the first 16 days of coincident observation. On September 14, 2015, the Advanced LIGO detectors observed a transient gravitational-wave signal determined to be the coalescence of two black holes [B. P. Abbott et al., Phys. Rev. Lett. 116, 061102 (2016)], launching the era of gravitational-wave astronomy. The event, GW150914, was observed with a combined signal-to-noise ratio of 24 in coincidence by the two detectors. Here, we present the main features of the detectors that enabled this observation. At full sensitivity, the Advanced LIGO detectors are designed to deliver another factor of 3 improvement in the signal-to-noise ratio for binary black hole systems similar in mass to GW150914.

Observation of Gravitational Waves from a Binary Black Hole Merger

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

Prospects for Observing and Localizing Gravitational-Wave Transients with Advanced LIGO and Advanced Virgo

We present a possible observing scenario for the Advanced LIGO and Advanced Virgo gravitational-wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We determine the expected sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. We report our findings for gravitational-wave transients, with particular focus on gravitational-wave signals from the inspiral of binary neutron-star systems, which are considered the most promising for multi-messenger astronomy. The ability to localize the sources of the detected signals depends on the geographical distribution of the detectors and their relative sensitivity, and 90% credible regions can be as large as thousands of square degrees when only two sensitive detectors are operational. Determining the sky position of a significant fraction of detected signals to areas of 5 deg2 to 20 deg2 will require at least three detectors of sensitivity within a factor of ∼ 2 of each other and with a broad frequency bandwidth. Should the third LIGO detector be relocated to India as expected, a significant fraction of gravitational-wave signals will be localized to a few square degrees by gravitational-wave observations alone.

Evaluating iterative algebraic algorithms in terms of convergence and image quality for cone beam CT

Cone beam computed tomography (CBCT) enables a volumetric image reconstruction from a set of 2D projection data. It plays an important role in image guided radiation therapy (IGRT). However, it is desirable to lower the patient radiation dose while maintaining good quality tomographic reconstructions. Hence, methods are needed even when the data is undersampled or there are limited projections. Iterative algorithms such as ART, SART and OS-SART are known to perform well under such circumstances. The performance of ART, SART and OS-SART is here studied based on a range of norm measurements (RMS reconstruction error, RMS projection error, and the L1 norm and L2 norm of the image error). Image quality measurements for uniformity and noise are also introduced. Since image quality often degrades as iterative algorithms converge, a simple function is used to trade off convergence with image quality. Investigations are performed using simulated and experimental data.

Abstract P6-04-12: Novel selective estrogen receptors degraders regress tumors in pre-clinical models of endocrine-resistant breast cancer

80% of all breast cancers express the estrogen receptor alpha (ERα) and thus are treated with anti-hormonal therapies that directly block ER function (e.g. Tamoxifen) or hormone synthesis (Aromatase Inhibitors). While these therapies are initially effective, acquired resistance invariably emerges. Importantly, the majority of these tumors continue to depend on ERα for growth and survival. The emerging evidence that ERα can signal in both a ligand-dependent and ligand-independent manner supports the development of agents that are not only competitive ERα antagonists but also reduce steady state levels of the receptor and thus limit both modes of signaling.

We have identified novel, non-steroidal ERα antagonists that induce degradation of ERα in breast cancer cell lines at picomolar concentrations resulting in significant reduction in steady state ERα protein levels. Using peptide-based conformational profiling, we show that these Selective Estrogen Receptor Degraders (SERDs) induce estrogen receptor conformations that are distinct from both fulvestrant and tamoxifen indicating a unique mechanism of action. This unique biological profile coupled with good oral pharmacokinetics produces tumor regressions in both tamoxifen-sensitive and -resistant models of breast cancer in vivo. Recent pre-clinical and clinical data indicate that PI3K pathway signaling can contribute to the endocrine resistant state. In a preclinical model of tamoxifen resistant breast cancer in which SERD monotherapy only produces tumor growth inhibition, SERD therapy in combination with torc1/2 inhibition results in frank tumor regressions. These orally bioavailable SERDs hold promise as a next generation therapy for the treatment of ER+ breast cancer as monotherapy, as well as in combination with agents that target other pathways involved in both intrinsic and acquired endocrine resistance.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-04-12.

Cone Beam CT using motion-compensated algebraic reconstruction methods with limited data

Cone Beam Computed Tomography (CBCT) is widely used in radiation therapy for verifying treatment areas, since it provides three-dimensional image reconstruction of those tumour regions under inspection. However, organ motion is problematic during the scanning process, it causes motion artefacts on the CBCT image and can lead to mispositioning for the subsequent treatment. Moreover, patient dose is also considerable and there is a need for methods which yield acceptable image quality with as few X-ray images as possible. Although methods have been developed to handle limited projection data, such as the Algebraic Reconstruction Technique (ART); Simultaneous ART (SART); and Ordered-Subset SART (OS-SART), this study applied motion compensation to these reconstruction techniques. Root Mean Square Error (RMSE) of image is calculated to study the convergence of reconstructed images compared with the truth image. When motion was applied to a phantom and the motion compensation was used to account for the motion, the results showed that motion compensation improved the quality of CBCT image, when compared to uncompensated images. Furthermore, the experiments suggested that minimising phase error, for breathing models, was more important than minimising amplitude error.

Directional limits on persistent gravitational waves using LIGO S5 science data

The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2-20×10(-50)  strain(2) Hz(-1) and 5-35×10(-49)  strain(2) Hz(-1) sr(-1) for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as ≈7×10(-25) in the most sensitive frequency range near 160 Hz.

Effect of the novel anti-androgen ARN-509 on response and seizure in castration-resistant prostate cancer models

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Background: ARN-509 is a second-generation anti-androgen discovered in a screen to identify full androgen receptor (AR) antagonists in the context of AR over-expressing prostate cancer cells, a model for castration resistant prostate cancer (CRPC). It has been reported that other second-generation anti-androgens, MDV3100 and BMS-641988, can induce seizures at high dose in pre-clinical species and man and that this is mediated through antagonism of the CNS-based GABAA receptor. To define the clinical potential of ARN-509, we carried out a comprehensive assessment of its in vitro and in vivo activity in validated models of CRPC and assessed its seizure inducing potential.

Methods: ARN-509 and MDV3100 were profiled in a series of assays to monitor both on- and off-target activity. Comparative in vivo efficacy in the LNCaP/AR mouse xenograft model of CRPC and pharmacokinetics were determined. Seizure inducing potential was assessed in an acute pentylenetetrazol (PTZ) infusion model.

Results: In vivo, in the LNCaP/AR model of CRPC, an ARN-509 dose of 10 mg/kg/day exhibited tumors regressions equivalent in frequency and magnitude to a 30 mg/kg/day dose of MDV3100. Tumor re-growth following once daily dosing (30 mg/kg) for 28 days revealed that ARN-509 treated tumors exhibited a more durable response than MDV3100 treated tumors as evidenced by a significantly longer time to re-growth. At doses that yielded equivalent degree of tumor regression, the steady state plasma and brain levels were significantly lower for ARN-509 (10 mg/kg) than MDV3100 (30 mg/kg). ARN-509 and MDV3100 exhibit similar binding affinity to the GABAA receptor; IC50 3.0 and 2.7 mM, respectively. In vivo seizure potential of ARN-509 and MDV3100 was assessed in an acute PTZ infusion model in mice. MDV3100 was found to produce a dose dependant lowering of seizure threshold, while ARN-509 had no effect at any dose tested.

Conclusions: ARN-509 is a second-generation anti-androgen with significant efficacy and an appropriate safety profile that supports its clinical development in both CRPC and earlier stages of prostate cancer. ARN-509 is currently in a phase I/II study in CRPC patients.

[Table: see text]

Investigations of dc electrical properties in electron-beam modified carbon nanotube films: single- and multiwalled

Carbon nanotubes (CNTs) in the family of nanostructured carbon materials are of great interest because of several unique physical properties. For space applications, it needs to be shown that CNTs are physically stable and structurally unaltered when subjected to irradiation becomes indispensable. The CNT films were grown by microwave Carbon nanotubes (CNTs) in the family of nanostructured carbon materials are of great interest because of several unique physical properties. For space applications, it needs to be shown that CNTs are physically stable and structurally unaltered when subjected to irradiation becomes indispensable. The CNT films were grown by microwave plasma-assisted chemical vapor deposition (MWCVD) technique using Fe as catalyst. Synthesis of both single- and multiwalled CNTs (SW and MW, respectively) were achieved by varying the thickness of the Fe catalyst layer. To investigate the influence of electron-beam irradiation, CNTs were subjected to low and/or medium energy electron-beam irradiation continuously for a few minutes to several hours. The CNT films prior to and post-irradiation were assessed in terms of their microscopic structure and physical properties to establish property-structure correlations. The characterization tools used to establish such correlations include scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy (RS), and current versus voltage (I-V) measuring contact resistance (two-probe) and dc conductivity (four-probe) properties. Dramatic improvement in the I-V properties for single-walled (from semiconducting to quasi-metallic) and relatively small but systematic behavior for multi-walled (from metallic to more metallic) with increasing irradiation hours is discussed in terms of critical role of defects. Alternatively, contact resistance of single-walled nanotubes decreased by two orders of magnitude on prolonged E-beam exposures. Moreover, these findings provided onset of saturation and damage/degradation in terms of both the electron beam energy and exposure times. Furthermore, these studies apparently brought out a contrasting comparison between mixed semiconducting/metallic (single-walled) and metallic (multiwalled) nanotubes in terms of their structural modifications due to electron-beam irradiation.

All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.

All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.

All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.

All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.

Search for gravitational-wave bursts from soft gamma repeaters

We present a LIGO search for short-duration gravitational waves (GWs) associated with soft gamma ray repeater (SGR) bursts. This is the first search sensitive to neutron star f modes, usually considered the most efficient GW emitting modes. We find no evidence of GWs associated with any SGR burst in a sample consisting of the 27 Dec. 2004 giant flare from SGR 1806-20 and 190 lesser events from SGR 1806-20 and SGR 1900+14. The unprecedented sensitivity of the detectors allows us to set the most stringent limits on transient GW amplitudes published to date. We find upper limit estimates on the model-dependent isotropic GW emission energies (at a nominal distance of 10 kpc) between 3x10;{45} and 9x10;{52} erg depending on waveform type, detector antenna factors and noise characteristics at the time of the burst. These upper limits are within the theoretically predicted range of some SGR models.

Hyperthyroidism impairs pancreatic beta cell adaptations to late pregnancy and maternal liporegulation in the rat

AIMS/HYPOTHESIS

Hyperthyroidism modifies lipid dynamics (increased oxidation), impairs insulin action and can suppress insulin secretion. We therefore examined the impact of hyperthyroidism on the relationship between glucose-stimulated insulin secretion (GSIS) and insulin action, using late pregnancy as a model of physiological insulin resistance that is associated with compensatory insulin hypersecretion to maintain glucose tolerance. Our aim was to examine whether hyperthyroidism compromises the regulation of insulin secretion and the ability of insulin to modulate circulating lipid concentrations in late pregnancy.

MATERIALS AND METHODS

Hyperthyroidism was induced by tri-iodothyronine (T(3)) administration from day 17 to 19 of pregnancy. GSIS was assessed during an IVGTT and during hyperglycaemic clamps in vivo and in vitro, using step-up and -down islet perifusions.

RESULTS

Hyperthyroidism in pregnancy elevated the glucose threshold for GSIS and impaired GSIS at low and high glucose concentrations in islet perifusions. In the intact animal, insulin secretion (after bolus glucose) was more rapidly curtailed following removal of the glucose stimulus to secretion. In contrast, GSIS was maintained during protracted hyperglycaemia (hyperglycaemic clamps) in the hyperthyroid pregnant state in vivo.

CONCLUSIONS/INTERPRETATION

Hyperthyroidism in vivo during late pregnancy blunts GSIS in subsequently isolated and perifused islets at low and high glucose concentrations. It also adversely affects GSIS under conditions of an acute glucose challenge in vivo. In contrast, GSIS is maintained during sustained hyperglycaemia in vivo, suggesting that in vivo factors can rescue GSIS. The ability of insulin to suppress systemic lipid levels during hyperglycaemic clamps was impaired. We therefore suggest that higher circulating lipids may preserve GSIS under conditions of sustained hyperglycaemia in the hyperthyroid pregnancy.

Interactive influences of peroxisome proliferator-activated receptor alpha activation and glucocorticoids on pancreatic beta cell compensation in insulin resistance induced by dietary saturated fat in the rat

AIMS/HYPOTHESIS

We sought to elucidate whether excess glucocorticoids and increased dietary lipids act synergistically to impair glucose tolerance and, if so, whether activation of peroxisome proliferator-activated receptor alpha (PPARalpha) has an adverse or beneficial effect on glucose tolerance.

METHODS

Dexamethasone (100 microg kg(-1) body weight day(-1); 5 days) was administered to insulin-resistant rats fed a high-saturated-fat (HF) diet for 4 weeks. The PPARalpha agonist WY14643 was administered (50 mg kg(-1) body weight intraperitoneally) 24 h before sampling. Glucose-stimulated insulin secretion (GSIS) was assessed in vivo after an acute glucose bolus injection, and in vitro using step-up and step-down islet perifusions.

RESULTS

Although neither PPARalpha activation nor dexamethasone alone affected fasting glycaemia in the HF group, dexamethasone in combination with PPARalpha activation elicited marked postabsorptive hyperglycaemia. Dexamethasone treatment of HF rats had little effect on GSIS after an acute glucose challenge in vivo, but induced glucose intolerance. PPARalpha activation augmented GSIS in dexamethasone-treated HF rats in vivo, restoring glucose tolerance. Contrasting with data obtained in vivo, greatly enhanced peak rates of GSIS were observed ex vivo in perifusions of islets from dexamethasone-treated HF rats compared with those from untreated HF rats, an effect attenuated by antecedent PPARalpha activation.

CONCLUSIONS/INTERPRETATION

The study demonstrates that glucocorticoid excess precipitates the development of glucose intolerance in rats maintained on a high-saturated-fat diet. It does this by interrupting the negative feedback loop between insulin sensitivity and secretion in vivo, such that further enhancement of compensatory insulin secretion is not possible. PPARalpha activation restores the coupling between insulin secretion and action.

Renal Tumors in Young Adults

PURPOSE

The clinical and pathological features of solid or complex cystic renal masses in young adults have not been defined. We present our experience with patients 17 to 45 years old with such renal masses to define the incidence of malignant vs benign lesions, familial tendencies and clinical outcomes.

MATERIALS AND METHODS

The medical records of all patients 17 to 45 years old who presented with a solid or suspicious complex cystic renal mass at 2 tertiary care hospitals between 1988 and 2002 were retrospectively reviewed. Pertinent clinical information was compiled, including age, gender, mode of presentation, renal function, year and type of surgery, pathological analysis and survival data.

RESULTS

There were 114 evaluable patients who underwent a total of 119 nephrectomies. Mean patient age was 37.1 years and males comprised 56.1% of the population. Twelve patients had familial renal cell carcinoma (RCC), the von Hippel-Lindau syndrome. Mode of presentation for patients with sporadic disease was symptomatic (55.9%), incidental (35.3%) or unknown (8.8%). Radical nephrectomy, partial nephrectomy and nephroureterectomy were performed in 80 kidneys (67.2%), 37 (31.1%) and 2 (1.7%), respectively. Malignant lesions comprised 79.8% of all masses and 95.8% of these were renal cell carcinoma. Of the RCCs 75.8% were grade 1 or 2 and 89% were organ confined. Young women were much more likely than men to have a benign lesion (36.0% vs 9.5%, p <0.01) and the diversity of histologies was impressive (of the 24 total benign masses 9 were different tumor types). With an average followup of 38.3 months overall survival is 90.2%. Among patients with RCC 84.9% are alive and cancer-free, 11.6% are dead from disease and 3.5% are alive with recurrent disease.

CONCLUSIONS

We report the largest known series of solid or suspicious complex renal masses in young adults. As expected, familial tumors are more common in this population. While RCC is the most common tumor, a wide variety of potential pathological outcomes are possible, particularly in women, who were much more likely to have a benign lesion. RCC in this patient population appears to have a favorable prognosis, despite symptomatic presentation in the majority of cases.

Acute (24 h) activation of peroxisome proliferator-activated receptor-alpha (PPARalpha) reverses high-fat feeding-induced insulin hypersecretion in vivo and in perifused pancreatic islets

Abnormal depletion or accumulation of islet lipid may be important for the development of pancreatic beta cell failure. Long-term lipid sensing by beta cells may be co-ordinated via peroxisome proliferator-activated receptors (PPARs). We investigated whether PPARalpha activation in vivo for 24 h affects basal and glucose-stimulated insulin secretion in vivo after intravenous glucose administration and ex vivo in isolated perifused islets. Insulin secretion after intravenous glucose challenge was greatly increased by high-fat feeding (4 weeks) but glucose tolerance was minimally perturbed, demonstrating insulin hypersecretion compensated for insulin resistance. The effect of high-fat feeding to enhance glucose-stimulated insulin secretion was retained in perifused islets demonstrating a stable, long-term effect of high-fat feeding to potentiate islet glucose stimulus-secretion coupling. Treatment of high-fat-fed rats with WY14,643 for 24 h reversed insulin hypersecretion in vivo without impairing glucose tolerance, suggesting improved insulin action, and ex vivo in perfused islets. PPARalpha activation only affected hypersecretion of insulin since glucose-stimulated insulin secretion was unaffected by WY14,643 treatment in vivo in control rats or in perifused islets from control rats. Our data demonstrate that activation of PPARalpha for 24 h can oppose insulin hypersecretion elicited by high-fat feeding via stable long-term effects exerted on islet function. PPARalpha could, therefore, participate in ameliorating abnormal glucose homeostasis and hyperinsulinaemia in dietary insulin resistance via modulation of islet function, extending the established requirement for PPARalpha for normal islet lipid homeostasis.

The role of hypoxia and p53 in the regulation of angiogenesis in bladder cancer

PURPOSE

Our previous studies defined thrombospondin-1 (TSP-1) and vascular endothelial growth factor (VEGF) as the primary mediators of angiogenesis in the bladder and the loss of inhibitory TSP-1 as a key event in the transition to an angiogenic phenotype during bladder cancer development. We evaluated the role of p53, which is commonly inactivated in bladder cancer, and hypoxia in the regulation of angiogenesis in the bladder.

MATERIALS AND METHODS

The p53 status was modulated in normal urothelial and bladder cancer cells, and conditioned media was collected under normal oxygen or hypoxic (0.5% O2) conditions. Angiogenic activity was evaluated with the endothelial cell migration assay, and the levels of secreted TSP-1 and VEGF were determined by Western blot analysis and enzyme-linked immunosorbent assay, respectively.

RESULTS

Retroviral mediated expression of the E6 oncoprotein reduced wild-type p53 levels in normal urothelial cells by greater than 90% but did not significantly alter TSP-1 or VEGF levels, while total inductive and inhibitory activities remained unchanged. Adenoviral mediated expression of wild-type p53 was confirmed in 4 bladder cancer cell lines by Western blot analysis for p53 and its downstream effector protein p21 (2.5 to 5.0-fold increase). TSP-1 levels remained unchanged but the levels of secreted VEGF in the high grade UMUC-3 and 253J cell lines were significantly decreased 5 to 50-fold and a corresponding decrease in net angiogenic activity was observed. However, (increased expression) of p53 had no effect on the angiogenic activity of the low grade RT4 or high grade HT1376 bladder cancer cells. Hypoxia converted normal urothelial cell derived conditioned media from anti-angiogenic to angiogenic and increased the angiogenic activity of bladder cancer cell derived conditioned media. This change was due to 2.5 to 6-fold hypoxic up-regulation of VEGF because the expression of inhibitory TSP-1 was not significantly altered.

CONCLUSIONS

Our results suggest that p53 does not regulate angiogenesis in the bladder in the setting of an otherwise normal genome and gene therapy with wild-type p53, which is currently being studied for this cancer, may have only limited effects on angiogenesis. In contrast, hypoxia regulates angiogenesis in this system, primarily through its effects on VEGF.

Excessive glucocorticoid exposure during late intrauterine development modulates the expression of cardiac uncoupling proteins in adult hypertensive male offspring

We investigated the impact of intrauterine growth retardation and fetal programming of hypertension by maternal dexamethasone treatment on cardiac uncoupling protein (UCP) expression during development and in adulthood in the rat. Dexamethasone administered via an indwelling osmotic pump (100 micrograms/kg body mass per day from day 15 of gestation) decreased fetal body mass at day 21 of gestation (by 13%; P < 0.05), elicited significant (+24%, P < 0.01) systolic hypertension and elevated corticosterone levels (+15%; P < 0.05) in adult (24-week-old) male offspring. Cardiac UCP-2 and UCP-3 protein expression was significantly upregulated during early postnatal development, reaching 1.7-fold and 2.7-fold the respective fetal day-21 levels by postnatal day 7 and reaching plateaus at postnatal days 15-21 (2.5-fold and 3.5-fold of respective fetal levels). Cardiac UCP protein expression at fetal day 21 and the ontogeny of cardiac UCP expression during early postnatal life were unaffected by prenatal dexamethasone treatment. Prenatal dexamethasone treatment did not abrogate the postnatal surge in corticosterone levels or modify plasma non-esterified fatty acid (NEFA) levels over this period. However, UCP-2 and UCP-3 protein expression was significantly downregulated in the hearts of adult hypertensive male offspring of dexamethasone-treated mothers (to 27% and 65% of control values respectively). We propose that changes in cardiac UCP protein expression are linked with changes in cardiac metabolic fuel selection (from glucose-->fatty acids at birth and from fatty acids-->glucose during hypertension).

The efficacy and safety of synchronous bilateral extracorporeal shock wave lithotripsy

PURPOSE

Bilateral renal calculi have traditionally been managed by staged extracorporeal shock wave lithotripsy (ESWLdagger) due to concern about bilateral obstruction. We evaluated the safety and efficacy of synchronous bilateral ESWL in a large series of patients treated at our institution to determine the safety and efficacy of this controversial technique in what is to our knowledge the largest series to date.

MATERIALS AND METHODS

We retrospectively evaluated the records of 120 patients with a mean age of 48 years who underwent bilateral synchronous ESWL between 1987 and 1996. Of the patients 71 (59%) were male. Average followup was 21 months. ESWL was performed using a Dornier HM3 lithotriptor in all cases. Intraoperative technique and postoperative factors were analyzed using the Pearson product moment correlation, the 2-tailed t test and multiple regression analysis.

RESULTS

Mean stone size was 13 and 15 mm. on the left and right sides, respectively. There was an average of 1.7 stones per renal unit. After 1 treatment 72 of the 120 patients (60%) were stone-free bilaterally, while 72% and 73% of left and right renal units, respectively, were also stone-free. Mean creatinine was similar preoperatively and postoperatively (1.46 and 1.41 mg./dl., respectively, p = 0.73). There was 1 or more complications in 18 cases. The majority of complications were minor with no long-term morbidity or death and there was no case of bilateral obstruction or renal failure. Additional procedures were required in 19 patients (16%) due to significant residual stone disease or obstruction during followup. Multiple regression analysis revealed that only patient age, a right ureteral stent and the number of shocks correlated with the complication rate. Stone size and number independently increased the probability of treatment failure and a repeat procedure (p <0.05). Patients with stones 20 mm. or greater were at particularly high risk for treatment failure and additional procedures. A total of 27 of the 35 patients (77%) with residual calculi and 13 of the 19 (68%) requiring additional procedures were in this high risk subgroup.

CONCLUSIONS

Bilateral synchronous ESWL is safe and effective monotherapy for bilateral urolithiasis. No patient had bilateral obstruction or renal failure and no deterioration of renal function was detected at followup. Knowing which patient populations are at higher risk for failure or complications may guide decision making.

Combined osteolathyric effects of beta-aminopropionitrile and penicillamine on Xenopus embryos: statistical comparison with dose-addition and independence

The combined osteolathyric effects of beta-aminopropionitrile (beta APN) and penicillamine (PNC) on developing Xenopus embryos were determined and compared with theoretical effects for the dose-addition and independence models. The testing protocol utilized a 1.2-factor matrix design that generated two single chemical and seven mixture concentration-response curves within 36 treatments. Testing was for 96-h with daily solution removal and replacement. The chi 2 goodness-of-fit test was used to compare experimental responses with theoretical responses. Response curve analyses indicated, in general, a combined effect between that expected for dose-addition and that for independence, which is a combined effect typical of chemicals acting dissimilarly.

Total protein and acid phosphatase concentrations in prostatic fluid from patients with BPH compared to carcinoma

OBJECTIVE

To obtain evidence of metabolic changes in the human prostate associated with prostate pathology, in particular carcinoma of the prostate, by identifying and evaluating associated changes in prostatic secretory products.

METHODS

Expressed prostatic fluid (EPF) from 36 patients with carcinoma, 128 with BPH histologically confirmed, and 148 with clinical BPH was subjected to determination of protein (Lowry; UV 280 nm absorption), enzymatic (DMA modified Row procedure) acid phosphatase (AcP), and immunologically identified (Tandem-PAP immunoenzymatic assay) prostatic acid phosphatase (PAP) concentration.

RESULTS

The important EPF findings are the following: (1) Protein concentrations (Lowry and UV determinations) are significantly increased in carcinoma as compared to histologic BPH, (2) AcP and PAP secretions remain stable in carcinoma versus BPH, and (3) AcP and PAP/Lowry protein ratios are significantly lower with carcinoma.

CONCLUSIONS

These findings of increased protein and the decreased relative secretions of AcP and PAP to total protein (ratio) in EPF from patients with carcinoma compared to BPH support and help to characterize the diffuse metabolic alteration in the prostate associated with prostate carcinoma. EPF observations identify potential metabolic changes occurring in prostate carcinoma that may have potential clinical and investigative relevance.

Transcatheter embolization of a ruptured superior gluteal artery aneurysm: case report and review of the literature

PURPOSE

To report the successful coil embolization of a true gluteal artery aneurysm and review therapeutic options for this rare condition.

METHODS AND RESULTS

A ruptured superior gluteal artery aneurysm in a symptomatic 80-year-old man was successfully thrombosed by embolization using a combination of Gianturco coils and helical platinum microcoils. Six-month computed tomography demonstrated persistent thrombosis of the aneurysm and resolution of the perivascular blood.

CONCLUSIONS

This report offers support for the use of catheter-based techniques as an alternative to standard surgical repair of gluteal artery aneurysms.

Long-term results of radical retropubic prostatectomy in men with high grade carcinoma of the prostate

PURPOSE

We sought to determine the efficacy of radical retropubic prostatectomy in men with high grade adenocarcinoma of the prostate in a population that had not been screened for prostate specific antigen (PSA).

MATERIALS AND METHODS

An inception cohort of 116 men surgically treated for prostate cancer between 1980 and 1991 was created in April 1992 and prospectively followed thereafter. Median followup was 7 years (range 2.2 to 14.6).

RESULTS

The major cause of death in this group of men was prostate cancer, not competing causes. Ten-year disease specific survival was 96% for organ confined (stage pT2c or less) and 78% for unconfined (stage pT3a or greater) disease. Five and 10-year PSA progression-free survival by pathological stage was 83 and 53% for organ confined disease, and 34 and 22% for unconfined disease with negative pelvic lymph node dissection (p = 0.001). Five and 10-year metastasis-free survival was 96% for organ confined disease, and 81 and 62% for unconfined disease (p = 0.011). Men with pelvic lymph node metastasis had 70 and 30% 5 and 10-year metastasis-free survival, and 75 and 55% disease specific survival, respectively. PSA progression-free survival was 33% at 5 years. A significantly decreased risk of PSA progression was observed in men with unconfined carcinoma who received adjuvant external beam radiotherapy.

CONCLUSIONS

In men with high grade prostate cancer the major cause of death was prostate cancer, not competing causes. Pathologically confined carcinoma had a significantly decreased rate of metastatic progression. These observations support the bias that early detection in these men at high risk for cause specific death may favorably impact survival.

Prostate specific antigen in the expressed prostatic fluid of men with benign prostatic hyperplasia and prostate carcinoma

PURPOSE

We tested the hypothesis that the histochemically demonstrated prostate specific antigen (PSA) content of prostate carcinoma cells does not necessarily reflect PSA production and secretion by evaluating expressed prostatic fluid.

MATERIALS AND METHODS

Expressed prostatic fluid and serum from 152 men with clinical benign prostatic hypertrophy (BPH), 132 with histologically proved BPH and 46 with prostate carcinoma were analyzed with the Hybritech PSA assay.

RESULTS

Expressed prostatic fluid PSA levels from carcinoma patients (median 1.70 mg./ml., mean 2.25) were significantly higher than in the histologically proved BPH group (median 1.28 mg./ml., mean 1.42, p < 0.05).

CONCLUSIONS

PSA concentration is increased in the expressed prostatic fluid of prostates of men with carcinoma compared to those with histological BPH. This finding may be a functional manifestation of a field change or paracrine effects within the prostate.

Bicarbonate-dependent and -independent intracellular pH regulatory mechanisms in rat hepatocytes. Evidence for Na+-HCO3- cotransport

Using the pH-sensitive dye 2,7-bis(carboxyethyl)-5(6)-carboxy-fluorescein and a continuously perfused subconfluent hepatocyte monolayer cell culture system, we studied rat hepatocyte intracellular pH (pHi) regulation in the presence (+HCO3-) and absence (-HCO3-) of bicarbonate. Baseline pHi was higher (7.28 +/- 09) in +HCO3- than in -HCO3- (7.16 +/- 0.14). Blocking Na+/H+ exchange with amiloride had no effect on pHi in +HCO3- but caused reversible 0.1-0.2-U acidification in -HCO3- or in +HCO3- after preincubation in the anion transport inhibitor 4,4'-diisothiocyano-2,2'-disulfonic acid stilbene (DIDS). Acute Na+ replacement in +HCO3- alos caused acidification which was amiloride independent but DIDS inhibitible. The recovery of pHi from an intracellular acid load (maximum H+ efflux rate) was 50% higher in +HCO3- than in -HCO3-. Amiloride inhibited H+ effluxmax by 75% in -HCO3- but by only 27% in +HCO3-. The amiloride-independent pHi recovery in +HCO3- was inhibited 50-63% by DIDS and 79% by Na+ replacement but was unaffected by depletion of intracellular Cl-, suggesting that Cl-/HCO3- exchange is not involved. Depolarization of hepatocytes (raising external K+ from 5 to 25 mM) caused reversible 0.05-0.1-U alkalinization, which, however, was neither Na+ nor HCO3- dependent, nor DIDS inhibitible, findings consistent with electroneutral HCO3- transport. We conclude that Na+-HCO3- cotransport, in addition to Na+/H+ exchange, is an important regulator of pHi in rat hepatocytes.

Protein kinase C agonists inhibit bile secretion independently of effects on the microcirculation in the isolated perfused rat liver

The role of hormones in the regulation of bile secretion is not known; however vasoactive agents, which act via the phosphoinositide signal transduction pathway, may mediate changes in bile flow by altering the hepatic microvasculature. We therefore examined the effects of phorbol esters and diacylglycerol, agonists of the protein kinase C branch of the phosphoinositide cascade, on perfusion pressure and bile flow in a single-pass, hemoglobin-free, isolated perfused rat liver system with constant perfusate flow. The active phorbol ester, 12,13-phorbol dibutyrate, produced a dose-dependent (maximal effect at 10(-6) M), sustained and reversible decrease in bile flow from 1.09 +/- 0.18 to 0.61 +/- 0.09 microliters per min per gm liver (37.2 +/- 5.9%) while simultaneously increasing perfusion pressure from 12.3 +/- 0.7 to 21.5 +/- 2.5 cm H2O (74.0 +/- 4.3%). Both effects were inhibited by the synthetic protein kinase C antagonist H-7. 1,2-Dioctanoyl-sn-glycerol, a diacylglycerol, produced changes in bile flow and perfusion pressure that were similar to, but more marked than, those caused by 12,13-phorbol dibutyrate, whereas the inactive phorbol ester 4 alpha-phorbol didecanoate and the vehicle dimethyl sulfoxide had no effects on either parameter. 12,13-Phorbol dibutyrate infusion resulted in reversible decreases in oxygen consumption (23.3%) and a reversible vascular redistribution of trypan blue dye but did not alter hepatic venous effluent concentrations of K+.(ABSTRACT TRUNCATED AT 250 WORDS)

Monitoring urinary bladder temperature

We evaluated bladder, rectal, and esophageal temperatures compared with nasopharyngeal temperatures in 12 patients who underwent cardiac surgery that required CPB. Changes in bladder temperature lagged behind those of esophageal and nasopharyngeal temperature during rapid cooling and rewarming. Changes in rectal temperature were the slowest. Bladder and rectal temperatures were similar after surgery. Monitoring bladder temperature represents the core temperature in a steady state.

Directional variability in the R wave response during serial exercise testing in patients with coronary artery disease

The reproducibility of the direction of R wave amplitude response to exercise was analyzed in patients with coronary artery disease. Forty-three serial exercise tests were performed by 10 patients with exertional angina pectoris and documented coronary artery disease (CAD). Seventeen tests (37%) resulted in no change or an increase in R wave amplitude (abnormal response). Twenty-six tests (63%) resulted in a decrease in R wave amplitude. The direction of the R wave amplitude response was variable in at least one exercise test in 7 of 10 patients with CAD, all of whom had reproducible ischemic ST segment responses during serial testing. The inconsistent R wave response in these patients was unrelated to heart rate, workload, or duration of exercise. Because of the variability in the directional R wave response during serial exercise testing in CAD patients, we conclude that the R wave response during exercise is unreliable for the detection of CAD or ischemia-related myocardial dysfunction.

Effect of albumin binding on extraction of sulfobromophthalein by perfused elasmobranch liver: evidence for dissociation-limited uptake

We investigated the role of serum albumin in the hepatic uptake of organic anions by determining the effect of added bovine albumin on sulfobromophthalein (BSP) uptake in skates, an animal which naturally lacks this protein. A single-pass perfused liver model was used to determine steady-state net uptake rates as the BSP or BSP and albumin concentrations were systematically varied. Results indicated that two different steps in the uptake process are capable of limiting the uptake rate depending on the albumin and BSP concentrations selected. At higher rates of uptake corresponding to higher BSP concentrations (up to 112 microM), saturation kinetics were observed as the BSP concentration was varied, with apparent Km and Vmax values which were independent of the albumin concentration (0.05 to 0.75%). These data suggest that under these conditions uptake is limited by a saturable step intrinsic to the liver. In contrast, for lower BSP concentrations and albumin concentrations below about 0.5%, a different kinetic pattern was seen which suggested that the rate-limiting step in uptake was transfer of BSP from albumin to the liver. The latter data were found to be consistent with a model in which the limiting step in the transfer process is spontaneous dissociation of the BSP from binding sites on albumin within the sinusoid. These results suggest that skate liver clears BSP from albumin solutions by a two-step mechanism in which dissociation from albumin is followed by a saturable process consistent with carrier-mediated transport. The albumin concentration and uptake velocity are important factors in determining which of these steps limits the uptake rate. Clearance is efficient and irreversible even though elasmobranch liver lacks high-affinity cytosolic binding proteins for BSP, and elasmobranch plasma does not normally contain albumin.

Pneumococcal-induced pulmonary leukostasis and hemodynamic changes: role of complement and granulocytes

In the present study we investigated the cardiopulmonary dysfunction caused by systemic pneumococcal (PNC) disease. We studied the hemodynamic and hematologic effects of intravascular challenge with nonviable PNC in normal, granulocyte-depleted, and genetically C3-deficient dogs. In normal dogs PNC administration caused a decrease in cardiac output (CO) of 58% (p less than 0.001), an increase in pulmonary vascular resistance (PVR) of 151% (p less than 0.02), and an increase in systemic vascular resistance (SVR) of 72% (p less than 0.02). The PNC challenge also caused significant decreases in both circulating granulocytes (-73%; p less than 0.02) and platelets (-58%; p less than 0.02). Histologic examination revealed granulocyte plugging within small pulmonary vessels. PNC challenge in granulocyte-depleted and C3-deficient dogs resulted in hemodynamic and hematologic changes that were not significantly different from those seen in normal PNC-challenged animals. Infusion of PNC-activated plasma resulted in hematologic changes that were not significantly different from those seen in PNC-challenged animals. Infusion of plasma treated with ethylenediamenetetraacetic acid (EDTA) prior to PNC incubation induced the same hematologic alterations but the hemodynamic response was less pronounced. To control for PNC constituents not removed by centrifugation and filtration, saline was incubated with PNC. After the PNC was removed, infusion of the saline induced no significant hemodynamic changes, although profound granulocytopenia occurred. We conclude that an intact complement system, but not normal numbers of circulating granulocytes, is essential to PNC-induced hemodynamic changes. PNC generates a plasma factor in vitro that does not require an intact complement system or cellular machinery to induce granulocytopenia without hemodynamic effect.