Sensory Responses To Environmental Tobacco Smoke From Tobacco-Burning And Tobacco-Heating Cigarettes

Sensory ratings, respiratory behavior and eye blink rate were recorded in 11 nonsmokers exposed to a no-smoking (CONTROL) condition or to environmental tobacco smoke (ETS) from one of three kinds of cigarettes: a Kentucky reference (1R4F), an ultra-low tar (ULT) and one that heats tobacco (TEST).For each two-hour session in a controlled-environment room, two smokers “puffed” unlit cigarettes, for the CONTROL condition, or smoked 16 cigarettes to generate ETS (sidestream plus exhaled mainstream smoke). Concentrations of nicotine and respirable suspended particles (RSP) observed with the 1R4F and ULT cigarettes were 10- to 20-fold higher than those typically found in field sampling studies of office and restaurant smoking environments. The ULT and TEST cigarettes resulted in ETS analyte concentrations that were 77-100% and O-56%, respectively, of those observed with 1R4E Sensory ratings (odor, irritation, annoyance, acceptability) with the two tobacco-burning cigarettes were similar and were much greater than those recorded for the TEST or CONTROL conditions which were, in turn, rated similarly. Respiratory parameters (respiratory rate, tidal volume, expiratory time), which generally failed to discriminate the TEST and CONTROL conditions, were altered during exposure to ETS from the 1R4F and, to a lesser extent, the ULT cigarette. Eye blink rate was not significantly altered by ETS from any of the cigarettes.     

The effect of cryosurgical ablation of the prostate on erectile function

OBJECTIVE: To investigate the incidence and identify the possible cause of erectile dysfunction after cryoablation of the prostate. PATIENTS AND METHODS: Erectile function was examined prospectively in 15 sexually active men (aged 59-72 years) who underwent cryoablation of the prostate for clinically localized prostate cancer. Erectile function was assessed before and 6 months after treatment; after intracavernosal injection with 10 micrograms of prostaglandin E1 (PGE1), the degree and duration of erection, the size of the cavernosal arteries, the penile arterial blood flow velocity, and the time to achieve peak flow were evaluated using high-resolution ultrasonography and colour pulsed-Doppler spectral analysis. RESULTS: Post-operatively, all patients initially reported an inability to achieve an erection sufficient for vaginal intercourse. At 6 months' follow-up, erectile dysfunction persisted in nine, with minimal or no response to the intracavernosal PGE1 injections, there was a significant decrease in the peak velocity of blood flow within cavernosal arteries and a significant increase in the time to achieve peak arterial flow. CONCLUSION: Although many factors may contribute to erectile dysfunction after cryoablation of the prostate, vascular injury plays a major role.     

Adaptive algorithms for a two-channel structure employing allpass filters, with applications to polarization mode dispersion compensation

A two-channel structure consisting of multiple cascades of allpass filters and directional couplers has certain desirable attributes. This paper considers adaptive algorithms for adjusting the parameters of such systems. The exemplary algorithms are motivated by an application to the compensation of polarization mode dispersion, which is a key problem in fiber optic systems. Gradient algorithms are shown to exhibit extremely slow convergence. This problem is solved by deriving a Newton-type algorithm. However, possible convergence to a local minimum emerges as a more fundamental problem. One of the conditions for local minima is specifically identified in terms of problematic parameter states.     

Clinical application of pulse oximetry

Pulse oximetry has become a common monitoring tool in critical care units over the past few years. But, as sometimes happens with new technology, use of the equipment can precede solid education about the applications and limitations of the device and how values should be interpreted.     

Effects of axial tension and reduced air pressure on the radialthermal conductivity of a strained conductor

Analysis of the radial flow of heat in a multilayer stranded conductor carrying current indicates that most of the heat is conducted through the very thin air gaps at the contracts between strands in adjacent layers and through the triangular or rectangular voids between layers. The theory predicts that, with constant current, the radial temperature difference increases as the axial tension decreases, and as the air pressure decreases. To confirm these predictions, a length of 91/4.04-mm AAC conductor was tensioned within a vacuum chamber, and the temperature of each layer of wires was measured for various total currents. It was found that the radial temperature difference increased with increasing resistive power loss per unit length, with decreasing axial tension, and with decreasing air pressure. The effective radial thermal conductivity is independent of the power loss, and increases with increasing axial tension and increasing air pressure. The calculated effective gap at the contacts is 0.5 to 0.9 μm     

Heme binding by a bacterial repressor protein, the gene product of the ferric uptake regulation (fur) gene of Escherichia coli

The fur gene product, Fur, of Escherichia coli is a repressor when it binds Fe(II). Since heme and iron metabolism are closely linked and Fur is rich in histidine, a ligand for heme, the binding of heme to Fur was investigated. The oxidized Fur-heme complex is stable and low spin with a Soret maximum at 404 nm and no 620-nm band. CO coordinates with the reduced heme-Fur complex, causing a shift from 412 nm to 410 nm, and stabilizes it, increasing the half-life from 5 to 15 min. Circular dichroism (CD) spectra in the Soret region show heme bound in an asymmetric environment in Fur, both in the oxidized and reduced-CO forms. Quenching of tyrosine fluorescence by heme revealed rapid, tight binding (Kd < 1 microM) with an unusual stoichiometry of 1 heme:1 Fur dimer. Fur binds Mn(II), a model ligand for the endogenous Fe(II), much more weakly (Kd > 80 microM). Far-ultraviolet CD spectroscopy showed that the alpha-helix content of apo-Fur decreases slightly with heme binding, but increases with Mn(II) binding. Competition experiments indicated that heme interacts with Fur dimers at the same site as Mn(II) and can displace the metal. In contrast to Mn(II), Zn(II) did not quench the tyrosine fluoroescence of Fur, affected the CD spectrum less than Mn(II), but did bind in a manner which prevented heme from binding. In sum, Fur not only binds heme and Zn(II) with sufficient affinity to be biologically relevant, but the interactions that occur between these ligands and their effects on Mn(II) binding need to be taken into account when addressing the biological function of Fur.