The prevalence and determinants of solar keratoses at a subtropical latitude (Queensland, Australia)

We report the association between skin pigmentation and individual sun exposure, and the occurrence of solar keratoses (SKs) in an unselected population, quantified for the first time. SKs were examined in a representative sample of 197 residents of the community of Nambour in Queensland, Australia. Estimates of sun exposure were combined with a measure of ultraviolet (UV) flux to estimate actual UV exposure, both occupational and recreational, during childhood and adult life. The number of episodes of painful sunburn was used as a measure of intermittent, intense UV exposure. Eight-three participants (43%) had at least one SK, while 35 (18%) had more than 10 SKs diagnosed. The age- and sex-adjusted odds ratios (ORs) for the development of SKs were higher in individuals with fair (OR = 14.1) or medium skin (OR = 6.5), compared with olive-skinned individuals. Individuals with poor ability to develop a suntan were similarly at increased risk compared with others. High levels of occupational UV exposure during adult life were confirmed as being strongly associated with prevalent SKs (OR = 2.4 for heavy/maximal adult exposure), with an even stronger association seen in those individuals with multiple SKs (OR = 4.3 for maximal adult exposure). Although no clear association was demonstrated between SK prevalence and accumulated childhood sun exposure, a history of even one episode of sunburn in childhood was strongly associated with SK prevalence (peak OR of 5.9 for one sunburn).     

Monte Carlo-aided dosimetry of a new high dose-rate brachytherapy source

In this article we introduce a new high-intensity 192Ir source design for use in a recently reengineered microSelectron-HDR remote afterloading device for high dose-rate (HDR) brachytherapy. The maximum rigid length and outer diameter of the new source are reduced to 4.95 and 0.90 mm, respectively, compared to 5.50 and 1.10 mm for the previous source design introduced in 1991. In addition, a smaller diameter and more flexible steel cable are used, allowing the source cable to negotiate smaller diameter catheters or more tortuously curved catheters. Using Monte Carlo photon transport simulation, the complete two-dimensional (2-D) dose-rate distribution is calculated over the 0.1-7 cm distance range and are presented both as conventional 2-D Cartesian lookup tables and in the formalism recommended by the American Association of Physicists in Medicine Task Group 43 (TG-43) Report. The dose distribution of this source is very similar to that of its predecessor, except near the source tip and in the shadow of the cable assembly, where differences of 5%-8% are apparent. The accuracy of various methods for extrapolating beyond the tubulated anisotropy functions to short distances is evaluated. It is demonstrated that linear extrapolation from the anisotropy functions defined by TG-43 accurately (+/- 2%) estimates dose rate at short and long distances lying outside the radial distance range of the original measured data from which the anisotropy and radial dose functions were derived. In contrast, the algorithm used on the vendor's planning system results in large calculation errors at distances less than 5 mm.     

Adaptation effects and reversible figures: a comment on Horlitz and O'Leary

Horlitz and O'Leary have provided further evidence for the important role of such top-down processes as attention and familiarity on reported reversals of ambiguous figures. As such, these results are consistent with the claims of several other investigators who have argued that any theory of phenomenal reversal that is based solely on passive neural processes is likely to be incomplete. However, Horlitz and O'Leary make the additional claims (1) that the several reports of adaptation effects in the literature are readily reinterpreted within an information-access framework and (2) that their own empirical work demonstrates a basic failure of neural-adaptation effects with reversible figures. It is proposed here that these claims must be viewed with caution. First, Horlitz and O'Leary's explanation for the discrepancy of their results from those of ostensibly similar experimental procedures in the reversible-figure literature is not the only, or the most likely, possibility. A plausible alternative model that posits critical procedural differences (specifically, duration of adaptation) across studies has been offered, and supporting empirical work for this latter suggestion has been presented. Second, the empirical efforts of Horlitz and O'Leary, while providing further evidence for top-down processes, do not eliminate the likely role of adaptation effects with reversible figures. There is strong reason to believe that the viewing conditions selected by these researchers may not have been sufficient to produce appreciable adaptation. Moreover, there is excellent reason to believe that both bottom-up and top-down processes moderate reported reversals of these figures.(ABSTRACT TRUNCATED AT 250 WORDS)     

Decrease in the ratio of high- to low-affinity isozymes of (Na+ +K+)-ATPase during the development of rat cardiac ventricles

The ratio of (Na+ +K+)-ATPase (EC 3.6.1.3.)isoforms with high and low affinity for cardiac glycosides was studied in heart preparations from neonatal, 3-month and 6-month old Wistar rats. Biphasic ouabain inhibition curves of (Na+ +K+)-ATPase activity indicated that the relative contribution of the high-affinity process decreased from 34% at 9 days to 23% at 3 months and to 10% at 6 months. Scatchard plots for [3H]ouabain binding were curvilinear and indicated that the relative contribution of the high-affinity sites (Kd = 0.1-0.25 microM) decreased by about one-half between 3 months (19-24%, N = 2) and 6 months (9-11%, N = 2).     

Upper abdominal surgery: does a lung function test exist to predict early severe postoperative respiratory complications?

We evaluated the capacity to predict severe respiratory complications (SRCs) following upper abdominal surgery (UAS) by using the results of a respiratory questionnaire and preoperative pulmonary function tests. Lung volumes, flows and transfer factor of the lung for carbon monoxide (TL,CO,sb) were assessed in 361 consecutive adult patients (248 males and 113 females). SRCs were diagnosed 24 h after UAS by clinical examination and chest radiography. Univariate and stepwise multiple logistic regression analyses were performed to estimate the odds ratio (OR) and 95% confidence interval (95% CI) of each single input variable, and to determine which indices best predicted outcome. These patients had a 1% mortality rate and 14% incidence of SRCs, with a male:female ratio of 0.86. The best predictors for SRCs by multiple analysis were: preoperative current hypersecretion of mucus (OR=133; p<0.0001); an increase in residual volume (RV) (OR=3.11; p=0.01); and, to a lesser extent, low percentage of predicted values both of forced expiratory volume in one second (FEV1 % pred) and TL,CO,sb. The algorithm thus obtained (logit theta) was extremely sensitive (84%), specific (99%), and accurate (95%) for preoperative prediction of SRCs. We have found that preoperative current hypersecretion of mucus and pulmonary hyperinflation, and to a lesser extent percentage predicted values both of forced expiratory volume in one second and transfer factor of the lung for carbon monoxide, have a significant predictive capacity for severe respiratory complications following upper abdominal surgery.