The effects of severe visual challenges on steering performance in visually healthy young drivers.

PURPOSE: Two experiments explored the extent to which induced blur, reduced luminance, and reduced visual fields affect drivers' steering performance in a driving simulator. METHODS: In experiment 1, ten young participants (M = 21.2 years) drove at approximately 89 km/h (55 mph) along a curvy roadway while being exposed to blur (0 to + 10 D), luminance (0.003 to 16.7 cd/m), and visual field (1.7 and 150 degrees) manipulations. In experiment 2, a new group of ten young participants (M = 18.5 years) drove while exposed to seven visual field sizes (1.7 to 150 degrees). RESULTS: Steering was sensitive to a reduced field size but not to the blur and luminance challenges. Acuity, on the other hand, was sensitive to the blur and luminance challenges but not to reduced field size. DISCUSSION: In healthy young drivers, steering performance is remarkably robust to severe blur and to extremely low luminances. These results support a key element of the selective degradation hypothesis advanced by Leibowitz and colleagues--that steering abilities are preserved at night even when the ability to recognize objects and hazards is not. Additional research should address the other element of this hypothesis--that drivers fail to appreciate the extent to which their visual abilities are degraded at night.     

The efficacy of intranasal interferon alpha-2a in respiratory syncytial virus infection in volunteers

In a double-blind, placebo-controlled study, self-administered intranasal interferon alpha-2a or placebo was given both before and after challenge with respiratory syncytial virus. The incidence of colds and the severity of signs and symptoms were reduced in those receiving interferon alpha-2a as compared with those given placebo. In a further double-blind, placebo-controlled study, self-administered interferon alpha-2a or placebo was given only to those volunteers who developed colds following challenge with respiratory syncytial virus. There was no evidence that interferon alpha-2a reduced the severity of the signs and symptoms or shortened the duration of the illness. The similarity of these results to the effect of interferon alpha-2a in rhinovirus infections in volunteers is discussed.     

Action spectra for human skin cells: estimates of the relative cytotoxicity of the middle ultraviolet, near ultraviolet, and violet regions of sunlight on epidermal keratinocytes

Action spectra for the cytotoxic action of electromagnetic radiation in the solar range 280-434 nm have been determined for human fibroblasts and epidermal keratinocytes derived from the same foreskin biopsy. The spectra for the two cell types are close to identical and coincide with our previously published data for a human lymphoblastoid line indicating that the mechanism of inactivation of the three human cell types is similar at any given wavelength. Using published data for ultraviolet transmission of human skin and sample spectral irradiance data, we have estimated the relative biological effectiveness of the middle ultraviolet (UVB) (290-320 nm), near ultraviolet (UVA) (320-380 nm), and violet (380-434 nm) regions of sunlight for cytotoxicity at the basal layer of the epidermis. We conclude that the UVB component in noon summer sunlight (the most UVB rich spectral conditions tested) may contribute only about 40% of the total cytotoxic effectiveness of sunlight at 290-434 nm. At lower zenith angles, UVA can account for up to 80% of the cytotoxic effectiveness of the combined UVA and UVB regions. Finally, a comparison of published action spectra data for human erythema with cytotoxicity data corrected for ultraviolet transmission to different depths of the human epidermis suggests that UVA erythema could be causally related to cytotoxicity occurring at an average depth of 40-50 micron into the human epidermis.     

Intraoperative Doppler flow studies: emphasis on colour mapping

Colour Doppler flow imaging (CD) is a well-established method of assessing valvular and congenital disease of the heart. The technique has proven useful intraoperatively in patients undergoing valve repair or replacement or intracardiac reconstruction. In 21 patients with various cardiac anomalies, colour Doppler flow imaging was used intraoperatively, before cardiac cannulation and again after cardiopulmonary bypass. Previously undisclosed features were demonstrated preoperatively in two patients and important residual defects after cardiopulmonary bypass in three others. Adequacy of valve replacement was confirmed in four patients and small leaks in ventricular septal defect patches were shown in another three. The procedure facilitated repair of complex cardiac fistulas in two patients. There were no apparent complications from CD. As intracardiac repairs become more complex, the role of intraoperative CD will expand.     

Endogenous glutathione levels modulate both constitutive and UVA radiation/hydrogen peroxide inducible expression of the human heme oxygenase gene.

Induction of the expression of the mammalian heme oxygenase gene appears to be a general response to oxidant stress. In view of the role of glutathione in protecting cells against solar UVA radiation and other forms of oxidant stress, we have investigated the relationship between intracellular glutathione levels and the inducibility of the human heme oxygenase gene after treatment of populations of cultured skin fibroblasts with either UVA radiation or hydrogen peroxide. We observe a clear relationship between cellular glutathione status and both the constitutive and oxidant-inducible accumulation of heme oxygenase mRNA. Glutathione depletion may lead to enhanced gene expression either as a result of the potentiated accumulation of active oxygen intermediates or as a result of the direct influence of glutathione on a critical target involved in signal transduction.