The influence of tissue depth and composition on the performance of the Lunar dual-energy X-ray absorptiometer whole-body scanning mode.

To assess the performance of the Lunar dual-energy X-ray absorptiometer (DPX) whole-body scanning mode (software version 3.1), a simple phantom was devised. This had known but variable amounts of lard to represent fat, and water to represent fat-free tissue. The bone mineral content of the phantom remained constant and consisted of the Lunar spine phantom to represent the spine/trunk and a slab of aluminium to represent the head. This phantom was scanned using the whole-body mode by the Lunar DPX to determine bone mineral content (BMC), area, bone mineral density (BMD), and body composition in terms of fat and fat-free tissue. The determinations of total tissue mass were very accurate and precise but fat tissue mass was slightly overestimated (103% of calculated value) and lean tissue mass slightly underestimated (98% of calculated value). The spine and head sections of the phantom were scanned individually using the spine mode and hence by addition the total BMC, area, and BMD of the whole phantom were determined. These results were compared to the bone mineral results obtained using the whole-body mode. The whole-body mode gave higher values for BMC and area than spine-mode measurements (at depths above 10 cm). This discrepancy increased with increasing depths of water (140% and 170% respectively of spine-mode value at soft-tissue depths of 22 cm and 15% fat). The values for BMD of the whole phantom tended to decrease with increasing depths of water and were lower than spine-mode values at tissue depths above 12cm.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of age-related changes in in vivo and in vitro measures of testicular steroidogenesis after acute cadmium exposure in the Sprague-Dawley rat

Previous reports have demonstrated that cadmium-(Cd-) induced testicular necrosis is an age-dependent process. However, little information exists on age-related intestitial cell (IC) damage in the rat after acute exposure to Cd. In this study in vitro and in vivo measures of testicular damage were utilized to compare the sensitivity of these measures and to further investigate age-related Cd-induced testicular damage. Testes, epididymides, and seminal vesicle weights, serum testosterone (sT), hCG-stimulated sT, and basal and stimulated IC testosterone (T) production were compared in rats 21 d following an injection of 2 mg Cd/kg at 9, 37, 67, and 97 d of age. The only Cd-related change noted for immature rats was an 84% reduction in sT. In rats injected when 37 d old, hCG-stimulated sT and epididymides and seminal vesicle weights, although depressed, were not significantly altered. However, all other measurements were significantly depressed. All measures of testicular damage were significantly depressed in rats injected at 67 and 97 d of age. Overall, in vitro measures were more sensitive indicators of Cd-induced testicular damage than in vivo measures. However, sT and hCG-stimulated sT appeared to be useful indicators of Cd effects on the pituitary-gonadal axis. ICs from immature rats (9 d old) were unaffected by Cd exposure, while stimulated T reproduction in ICs from 37-, 67-, and 97-d-old animals was reduced at least 50%. The severity of Cd-induced testicular damage increased with age for all variables measured.     

Heterometallic antenna?reactor complexes for photocatalysis

Metallic nanoparticles with strong optically resonant properties behave as nanoscale optical antennas, and have recently shown extraordinary promise as light-driven catalysts. Traditionally, however, heterogeneous catalysis has relied upon weakly light-absorbing metals such as Pd, Pt, Ru, or Rh to lower the activation energy for chemical reactions. Here we show that coupling a plasmonic nanoantenna directly to catalytic nanoparticles enables the light-induced generation of hot carriers within the catalyst nanoparticles, transforming the entire complex into an efficient light-controlled reactive catalyst. In Pd-decorated Al nanocrystals, photocatalytic hydrogen desorption closely follows the antenna-induced local absorption cross-section of the Pd islands, and a supralinear power dependence strongly suggests that hot-carrier-induced desorption occurs at the Pd island surface. When acetylene is present along with hydrogen, the selectivity for photocatalytic ethylene production relative to ethane is strongly enhanced, approaching 40:1. These observations indicate that antenna−reactor complexes may greatly expand possibilities for developing designer photocatalytic substrates.Industrial processes depend extensively on heterogeneous catalysts for chemical production and mitigation of environmental pollutants. These processes often rely on metal nanoparticles dispersed into high surface area support materials to both maximize catalytically active surface area and for the most cost-effective use of expensive catalysts such as Pd, Pt, Ru, or Rh (1, 2). However, catalytic processes utilizing transition metal nanoparticles are often energy-intensive, relying on high temperatures and pressures to maximize catalytic activity. A transition from extreme, high-temperature conditions to low-temperature activation of catalytically active transition metal nanoparticles could have widespread impact, substantially reducing the current energy demands of heterogeneous catalysis.Light-driven chemical transformations offer an attractive and ultimately sustainable alternative to traditional high-temperature catalytic reactions. Metallic plasmonic nanostructures are a new paradigm in photoactive heterogeneous catalysts (3–6). Plasmonic nanoparticles uniquely couple electron density with electromagnetic radiation, leading to a collective oscillation of the conduction electrons in resonance with the frequency of incident light, known as a localized surface plasmon resonance (LSPR). These resonances lead to enhanced light absorption in an area much larger than the physical cross-section of the nanoparticle, and such optical antenna effects result in strongly enhanced electromagnetic fields near the nanoparticle surface. An LSPR can be damped through radiative reemission of a photon, or nonradiative Landau damping with the creation of energetic “hot” carriers: electrons above the Fermi energy of the metal and/or holes below the Fermi energy. In this context, “hot” refers to carriers of an energy that is a significant fraction of the plasmon energy that would not be generated thermally at ambient temperature. Plasmonic metal nanoparticles have been shown to induce chemical transformations directly on their surfaces, through either phonon-driven or charge-carrier-driven mechanisms in Au (7–10), Ag (11, 12), Cu (13, 14), and, recently, Al (15) nanoparticles. Although these “good” plasmonic metals show initial promise for plasmon-induced photocatalytic chemistry, in general they are not universally good catalytic materials despite finding niche applications in a few industrial processes.In comparison, noncoinage transition metals have historical precedence as excellent catalysts, yet are generally considered poor plasmonic metals, because they suffer from large nonradiative damping, which results in broad spectral features and weak absorption across the visible region of the spectrum (16–18). Many catalytic transition metal nanoparticles (Pt, Pd, Rh, Ru, etc.) possess LSPRs in the UV, but this is disadvantageous for photocatalysis because of poor overlap with conventional laser sources or, alternatively, with the solar spectrum. Increasing transition metal nanoparticle size redshifts optical absorption, but it increases cost and reduces surface area, and therefore catalytic activity. Recently, it has been shown that plasmonic nanoparticles can be used to increase optical absorption in adjacent nanoparticles (19–22), for instance, enabling hydrogen detection (23, 24).Previous reports of photocatalytic transformation in plasmonic metal nanoparticle systems rely on the metal to double as both the light-harvesting antenna and the catalytic surface. Here we show that the optical antenna effects of plasmonic metal nanoparticles can be used to directly enhance light absorption and modify the catalytic activity of directly adjacent reactive metal nanoparticle surfaces. This “antenna−reactor” complex, with the antenna and reactor composed of two distinct materials, is illustrated schematically in Fig. 1A. We note that the experimental antenna−reactor complexes designed for this work are separated by 2- to 4-nm dielectric aluminum oxide interfacial layers rather than complete separation as illustrated in Fig. 1A. Here we show that antenna−reactor complexes, focusing on Al as the antenna and Pd as the reactor, can be used to photoactively drive catalytic reactions under mild, ambient temperature and pressure conditions. Such modular, heterometallic complexes offer greatly increased degrees of freedom in the design of photocatalytic complexes, expanding the possible materials that can be used as light-driven catalysts. Manipulating the materials used for both the plasmonic antenna and catalytic reactor can theoretically lead to numerous possibilities for controlling plasmon-assisted absorption enhancements and specific reactivities (SI Appendix, Figs. S1 and S2).Open in a separate windowFig. 1.Absorption enhancements in heterometallic antenna−reactor systems. (A) Generalized schematic of a simple system containing a plasmonic antenna coupled through localized near-field enhancements to a catalytic reactor metal nanoparticle. (B) A simplified Pd−AlNC antenna−reactor model, consisting of a 20-nm Pd island on a 110-nm-diameter AlNC nanosphere. (C) Near-field enhancement in the Pd island for this antenna−reactor geometry. (D) Schematic of a comparative geometry, a Pd island on a 110-nm-diameter dielectric Al₂O₃ nanosphere. (E) The near-field enhancement in this geometry is substantially reduced relative to C. (F) Absorption of Pd on Al₂O₃ (black) and an antenna−reactor geometry using FDTD (red solid curve) and isolated absorption multiplied by field enhancement (red dashed curve). Near-field enhancement in the Al₂O₃ layer of the AlNC is shown in blue.     

Quality of care and outcomes among patients with acute myocardial infarction by level of kidney function at admission: report from the get with the guidelines coronary artery disease program

Background:

Many patients admitted for acute myocardial infarction (AMI) have chronic renal insufficiency. We studied the impact of chronic renal insufficiency on mortality and quality of inpatient care for AMI from the American Heart Association's Get With The Guidelines–Coronary Artery Disease Program.

Hypothesis:

We hypothesized that mortality and quality of inpatient care would not vary with renal function.

Methods:

We examined in‐hospital AMI performance measures by renal function based on glomerular filtration rate (GFR). Severity of renal insufficiency was categorized as normal (GFR ≥ 90 mL/min/1.73 m 2 ), mild (GFR 60–90 mL/min/1.73 m 2 ), moderate (GFR 30–60 mL/min/1.73 m 2 ), severe (GFR 15–30 mL/min/1.73 m 2 ), and kidney failure (GFR ≤ 15 mL/min/1.73 m 2 or dialysis). A total of 21721 patients from 291 sites were studied, with most data collected in 2008 to 2009. Multivariable regression analysis after adjusting for patient characteristics was performed and generalized estimating equations were used to account for within‐hospital clustering. In‐hospital mortality and quality of inpatient care were assessed.

Results:

Renal insufficiency was present in 82.0 percent of AMI patients. The adjusted odds ratio vs normal renal function for mortality increased with worsening renal function: 1.45 for mild renal insufficiency (95% confidence interval [CI]: 1.03–2.05, P = 0.03); 3.36 for moderate renal insufficiency (95% CI: 2.31–4.89, P < 0.0001); 5.43 for severe renal insufficiency (95% CI: 3.70–7.95, P < 0.0001); and 6.35 for kidney failure (95% CI: 4.48–9.01, P < 0.0001). Patients with renal insufficiency received less inpatient and discharge guideline‐recommended therapy for AMI.

Conclusions:

Among AMI patients, mortality and guideline‐recommended inpatient therapy correlated inversely with renal function. Adjusted mortality was equally poor among patients with severe renal dysfunction and on dialysis. Clin. Cardiol. 2012 doi: 10.1002/clc.22021 Christopher P. Cannon, MD, has received research grants/support from Accumetrics, AstraZeneca, GlaxoSmithKline, Intekrin Therapeutics, Merck, and Takeda; is a member of the advisory board (funds donated to charity) of Bristol‐Myers Squibb/Sanofi, Novartis, and Alnylam; received an honorarium for development of independent educational symposia from Pfizer and AstraZeneca; and is a clinical advisor with equity in Automedics Medical Systems. Gregg C. Fonarow, MD, is a consultant for Novartis and Pfizer. W. Frank Peacock, MD, has received research grants (>$10000) from Abbott, Alere, Brahms, Corthera, EKR, Nanosphere, and The Medicines Company; is a consultant (<$10000) for Abbott, Alere, Beckman Coulter, Electrocore, and The Medicines Company; participates in the speakers' bureau (<$10000) with Abbott and Alere; and has an ownership interest (<$10000) in Comprehensive Research Associates LLC, Vital Sensors, and Emergencies in Medicine LLC. Lee H. Schwamm, MD, is a consultant for Stroke Systems and Medtronic. Deepak L. Bhatt, MD, MPH, discloses the following relationships ‐ Advisory Board: Medscape Cardiology; Board of Directors: Boston VA Research Institute, Society of Chest Pain Centers; Chair: American Heart Association Get With The Guidelines Science Subcommittee; Honoraria: American College of Cardiology (Editor, Clinical Trials, Cardiosource), Duke Clinical Research Institute (clinical trial steering committees), Slack Publications (Chief Medical Editor, Cardiology Today Intervention), WebMD (CME steering committees); Research Grants: Amarin, AstraZeneca, Bristol‐Myers Squibb, Eisai, Ethicon, Medtronic, Sanofi Aventis, The Medicines Company; Unfunded Research: FlowCo, PLx Pharma, Takeda. Sylvia E. Rosas has received a research grant from Abbott Laboratories and honorarium from Genzyme. The Get With The Guidelines‐Coronary Artery Disease (GWTG‐CAD) program was provided by the American Heart Association. The GWTG‐CAD program was supported in part through the American Heart Association Pharmaceutical Roundtable and an unrestricted educational grant from Merck. The authors have no other funding, financial relationships, or conflicts of interest to disclose. Additional Supporting Information may be found in the online version of this article.     

Age and Gender Differences in Quality of Care and Outcomes for Patients with ST-segment Elevation Myocardial Infarction

BackgroundYoung patients (aged ≤ 45 years) presenting with ST-segment elevation myocardial infarction present unique challenges. The quality of care and in-hospital outcomes may differ from their older counterparts.MethodsA total of 31,544 patients presenting with ST-segment elevation myocardial infarction and enrolled in the American Heart Association's Get With the Guidelines Coronary Artery Disease registry were analyzed. The cohort was divided into those aged 45 years or less and those aged more than 45 years.ResultsYoung patients accounted for 10.3% of all ST-segment elevation myocardial infarction cases. Compared with older patients, younger patients were less likely to have traditional cardiovascular risk factors and had similar or better quality/performance measures with lower in-hospital mortality (unadjusted rate 1.6 vs 6.5%, P <.0001; adjusted odds ratio [OR], 0.37; 95% confidence interval [CI], 0.29-0.46). Time trend analysis (2002-2008) suggested an increase over time in the “all or none” composite performance measure in both the younger and older patients (68%-97% and 69%-96%, respectively). However, there was significantly lower quality of care and worse outcomes in women (vs men) and in the very young (≤35 vs 36-45 years). Significant interaction was seen between age and gender for in-hospital death, such that the gender difference was greater in the younger cohort. Similar interaction was seen for door-to-thrombolytic time such that the gender delay was greater in the younger cohort (women:men ratio of means = 1.73, 95% CI, 1.21-2.45 [younger] vs 1.08, 95% CI, 1.00-1.18 [older]; P_interaction = .0031).ConclusionYoung patients aged 45 years or less presenting with ST-segment elevation myocardial infarction overall had similar quality of care and in-hospital outcomes as older counterparts. However, quality of care was significantly lower and mortality was higher in young women (vs young men) and the very young (≤35 vs 36-45 years).     

Multivariable model for prediction of risk of significant complication during diagnostic cardiac catheterization

Although adequate data exist on the frequency of procedural-related complications during diagnostic cardiac catheterization, little information is available for the quantitative assessment of risk factors for significant complication. We analyzed 58,332 procedures in the 1990 SCA&I Registry Database in order to assess (1) the independent and cumulative significance of easily obtainable pre-procedural factors predictive of major complication and (2) the likelihood of a significant complication given the presence of these risk factors. A model was developed on a random sample of 38,888 patients and validated in the remaining 19,444 patients. Twelve variables were identified as having independent predictive behavior for significant complication with excellent agreement in the validation sample. The current model is an accurate and reliable instrument for stratifying risk of a significant complication during diagnostic catheterization.© 1992 Wlley-Liss, Inc     

Effects of pacing tachycardia and balloon valvuloplasty on pulmonary artery impedance and hydraulic power in mitral stenosis.

BACKGROUND. Mitral stenosis is characterized by progressive pulmonary hypertension and eventual right ventricular failure. However, the correlation between right ventricular failure and the level of pulmonary hypertension is poor, suggesting that factors other than those recognized from nonpulsatile hemodynamic parameters may contribute to impaired right ventricular performance in this condition. METHODS AND RESULTS. We studied 16 patients with severe mitral stenosis (mean valve area, 1.0 +/- 0.2 cm2) at supine rest and during pacing tachycardia using high-fidelity catheter recordings of pulmonary artery (PA) pressure and flow velocity. Pulmonary impedance spectra, wave reflection properties, and hydraulic power data were derived from Fourier analysis of signal-averaged data. Pacing tachycardia (baseline heart rate, 81 +/- 11 beats per minute; pacing, 132 +/- 11 beats per minute) significantly raised pulmonary wedge and mean PA pressures. There was no change in pulmonary vascular resistance (209 +/- 144 to 232 +/- 164 dyne-sec/cm5) or PA characteristic impedance (62 +/- 25 to 55 +/- 28 dyne-sec/cm5). However, first harmonic impedance (Z1) significantly decreased (134 +/- 71 to 100 +/- 68 dyne-sec/cm5; p < 0.001). Accordingly, oscillatory and total dissipated hydraulic power per unit forward flow (WT/CO) fell during tachycardia (2.6 +/- 1.6 to 2.3 +/- 1.4 mW/ml.sec-1; p = 0.06) despite acute pulmonary hypertension. Reflected pressure waves returned earlier to the proximal PA, suggesting increased vessel stiffness. Immediately after percutaneous balloon mitral valvuloplasty (PBV) in eight of the patients, baseline and pacing data were again recorded. Compared with the pre-PBV baseline state, post-PBV resting data demonstrated no change in resistance or characteristic impedance, but there was a significant fall in Z1 (166 +/- 75 to 103 +/- 45 dyne-sec/cm5; p < 0.05) and in the magnitude of pulmonary wave reflections. WT/CO tended to decrease after PBV, and pacing after PBV produced a further decrease in WT/CO, again in association with lower Z1. CONCLUSIONS. These data demonstrate that 1) increased pulmonary characteristic impedance, although a feature of mitral stenosis, is not exacerbated by the acute effects of increased distending pressure; 2) pacing tachycardia in mitral stenosis causes little change in the pulmonary impedance spectrum except at low frequencies, where decreased impedance lowers power requirements per unit flow; and 3) relief of mitral stenosis produces immediate improvement in low-frequency impedance and in hydraulic power requirements. These findings suggest that although characteristic impedance may be a measure of the long-term effects of pulmonary hypertension on the pulmonary circulation, acute increases and decreases in PA pressure produce effects on right ventricular load that are best described in terms of the low-frequency properties of the PA system. Improvement in low-frequency impedance diminishes hydraulic power requirements and thus reflects improved ventricular-vascular coupling, irrespective of distending PA pressure. Efforts to treat or prevent right heart failure in the presence of pulmonary hypertension should take account of the potential benefit of changes in low-frequency impedance characteristics of the pulmonary vascular bed.     

Calcium entry-dependent oscillations of cytoplasmic calcium concentration in cultured endothelial cell monolayers.

Bovine endothelial cell monolayers grown to confluence and stimulated with bradykinin responded with periodic fluctuations in intracellular Ca2+ concentration ([Ca2+]i) when exposed to K(+)-free Hepes-buffered saline. The fluctuations in [Ca2+]i measured with fura-2 were synchronized among the population of cells observed and were sensitive to extracellular Ca2+ concentration ([Ca2+]o). Thapsigargin, which inhibits the endoplasmic reticular Ca2(+)-ATPase, did not inhibit the [Ca2+]i oscillations. Removal of extracellular Ca2+ or inhibition of Ca2+ entry by using La3+ or 1-(beta- [3-(4-methoxyphenyl)proproxy]-4-methoxyphenethyl)-1H-imidazole hydrochloride (SKF 96365) abolished the [Ca2+]i oscillations in endothelial cell monolayers. The fluctuations in [Ca2+]i were therefore dependent on Ca2+ influx rather than Ca2+ mobilization from intracellular stores. Simultaneous measurements of membrane potential (Em) using the potential-sensitive bisoxonol dye bis(1,3-dibutylbarbituric acid)trimethine oxonol [Di-BAC4(3)] and [Ca2+]i using fura-2 showed that Em oscillated at the same frequency as the fluctuations in [Ca2+]i. The peak depolarization signal coincided with the maximum rate of increase in the [Ca2+]i signal. Oscillations in the Em signal were inhibited by removal of Ca2+ or by addition of 1 mM Ni2+ to the external solution. Taken together, these observations suggest that the change in Em is the consequence of oscillatory changes in a membrane conductance that also allows Ca2+ to enter the cell. Oscillations in the DiBAC4(3) signal may reflect a rhythmic entry of Ca2+ through nonselective cation channels.