Is commercial alcohol availability related to adolescent alcohol sources and alcohol use? Findings from a multi-level study.

PURPOSE: To examine whether compliance with underage sales laws by licensed retail establishments is related to underage use of commercial and social alcohol sources, perceived ease of obtaining alcohol, and alcohol use. METHODS: In 2005, alcohol purchase surveys were conducted at 403 off-premise licensed retail establishments in 43 Oregon school districts. A survey also was administered to 3,332 11th graders in the districts. Multi-level logistic regression analyses were used to examine relationships between the school district-level alcohol sales rate and students' use of commercial and social alcohol sources, perceived ease of obtaining alcohol, past-30-day alcohol use, and heavy drinking. RESULTS: The school district-level alcohol sales rate was positively related to students' use of commercial alcohol sources and perceived alcohol availability, but was not directly associated with use of social alcohol sources and drinking behaviors. Additional analyses indicated stronger associations between drinking behaviors and use of social alcohol sources relative to other predictors. These analyses also provided support for an indirect association between the school district-level alcohol sales rate and alcohol use behaviors. CONCLUSIONS: Compliance with underage alcohol sales laws by licensed retail establishments may affect underage alcohol use indirectly, through its effect on underage use of commercial alcohol sources and perceived ease of obtaining alcohol. However, use of social alcohol sources is more strongly related to underage drinking than use of commercial alcohol sources and perceived ease of obtaining alcohol.     

The effect of pre-vertebroplasty tumor ablation using laser-induced thermotherapy on biomechanical stability and cement fill in the metastatic spine

A biomechanical study comparing simulated lytic vertebral metastases treated with laser-induced thermotherapy (LITT) and vertebroplasty versus vertebroplasty alone. To investigate the effect of tumor ablation using LITT prior to vertebroplasty on biomechanical stability and cement fill patterns in a standardized model of spinal metastatic disease. Vertebroplasty in the metastatic spine is aimed at reducing pain, but is associated with risk of cement extravasation in up to 10%. Six pairs of fresh-frozen cadaveric thoracolumbar spinal motion segments were tested in axial compression intact, with simulated metastases and following percutaneous vertebroplasty with or without LITT. Canal narrowing under load, pattern of cement fill, load to failure, and LITT temperature and pressure generation were collected. In all LITT specimens, cement filled the defect without extravasation. The canal extravasation rate was 33% in specimens treated without LITT. LITT and vertebroplasty yielded a trend toward improved posterior wall stability (P = 0.095) as compared to vertebroplasty alone. Moderate rises in temperature and minimal pressure generation was seen during LITT. In this model, elimination of tumor by LITT, facilitates cement fill, enhances biomechanical stability and reduces the risk of cement extravasation.     

An optimal regulator for linear systems with multiple state and input delays

This paper presents an optimal regulator for a linear system with multiple state and input delays and a quadratic criterion. The optimal regulator equations are obtained reducing the original problem to the linear‐quadratic regulator design for a system without delays. Performance of the obtained optimal regulator is verified in the illustrative example against the best linear regulators available for the linear system without delays and for two rational approximations of the original time‐delay system. Simulation graphs demonstrating better performance of the obtained optimal regulator with respect to the criterion value are included. Copyright © 2006 John Wiley & Sons, Ltd.     

Strategic planning in academic paediatric hospitals: The need for child health input

Over the past two decades, a number of Canadian paediatric academic programs, previously operated as separate hospitals, have been integrated into larger teaching hospitals or regional health authorities. The present article describes the recent experience of the Children’s Hospital of Western Ontario within the London Health Sciences Centre (London, Ontario) to illustrate the potential deleterious effects of planning, system and program changes in a large academic hospital without child health input at the executive decision-making level. The vision of the London Health Sciences Centre Executive Leadership Team and Board of Directors was divergent from that of the paediatric health care providers, which resulted in the resignation of a number of paediatric subspecialists and compromised the ability of the Department of Paediatrics to deliver paediatric care and educate future professionals. The present article highlights the need for the involvement of paediatric stakeholders in strategic planning in the hope that other academic centres can learn from this experience.     

Olfactomotor activity during imagery mimics that during perception

Neural representations created in the absence of external sensory stimuli are referred to as imagery, and such representations may be augmented by reenactment of sensorimotor processes. We measured nasal airflow in human subjects while they imagined sights, sounds and smells, and only during olfactory imagery did subjects spontaneously enact the motor component of olfaction--that is, they sniffed. Moreover, as in perception, imagery of pleasant odors involved larger sniffs than imagery of unpleasant odors, suggesting that the act of sniffing has a functional role in creating of olfactory percepts.     

Calcineurin B1 is essential for positive but not negative selection during thymocyte development

During development, discrete cell fates often result from variation in the intensity of a particular signal. The mechanisms underlying these seemingly analog-to-digital switches are not understood. In developing T lymphocytes, low-intensity signals through the antigen receptor result in positive selection while more intense signals give rise to negative selection. By deleting the genetic locus encoding the regulatory B1 subunit of calcineurin specifically in thymocytes, we found an absolute requirement for calcineurin in positive selection. In contrast, calcineurin activity was dispensable in several models of negative selection. Unexpectedly, we found that removal of calcineurin activity from thymocytes results in inefficient ERK activation at the double-positive stage of thymocyte development, when selection occurs. These studies clarify the mechanism by which graded signals are converted to discrete outcomes in T cell development and further indicate that the developmental roles of calcineurin likely contribute to immunosuppression by calcineurin inhibitors.     

Effects of increasing osmolality on rat ileal smooth muscle

The effects of changing bathing medium osmolality on tension generation in smooth muscle were studied on potassium-depolarized segments of rat ileum. Increasing the tonicity of the medium evokes a transient relaxation of the smooth muscle; restoration of isotonicity evokes a transient contraction of similar amplitude and time course. While immersed in hypertonic media of less than 1.3 times normal tonicity, the smooth muscle slowly increases its isometric tension; in media of nearly twice normal tonicity, the smooth muscle loses tension. All of these effects occur whether the medium is made hypertonic with added NaCl or sucrose.