Comparison of a PACS workstation with laser hard copies for detecting scaphoid fractures in the emergency department.

Picture archiving and communication systems (PACS) for imaging studies is rapidly being adopted in hospitals throughout the UK. However, very little comparison has been made between PACS and laser hard copies for assessing the diagnostic accuracy of detecting fractures by emergency physicians. A prospective paired comparison study was undertaken looking at correct reporting of scaphoid X-rays on PACS and conventional film by emergency department medical staff. A total of 34 imaging studies were reported by 38 physicians using both PACS workstations and laser-printed films. The percentage of emergency physicians correctly reporting imaging studies was similar when comparing PACS images to laser film copies (80.7% versus 81.0%). The sensitivity and specificity of PACS for diagnosing scaphoid fractures was 79.5% and 81.6%, versus 78.1% and 83.8% for conventional films. There is no significant difference in accuracy of diagnosis between PACS and laser film copies when scaphoid X-rays are reported by emergency physicians.

Trade-offs between activity and thermoregulation in a small carnivore, the least weasel Mustela nivalis.

We studied factors influencing daily energy expenditures (DEE) of male least weasels (Mustela nivalis) using the doubly labelled water technique. The relationship between ambient temperature and DEE formed a triangular pattern, characterized by invariance of the maximum DEE and an inverse relationship between minimum DEE and temperature. A simple energetic model relating the DEE of male weasels to activity time (AT) and ambient temperature predicted that, across seasons, less than 10 per cent of measurements approach the upper bound of observed DEE. Male weasels were able to maintain a relatively constant maximum energy output across varying temperatures by adjusting their AT to changes in temperature. They achieved maximum energy expenditures in winter due to high thermoregulatory costs, and in spring and summer due to high levels of physical activity. This pattern exemplifies a 'metabolic niche' of a small mammal having extremely high energy expenditures primarily driven by ambient temperature.

A vital role for voltage-dependent potassium channels in dopamine transporter-mediated 6-hydroxydopamine neurotoxicity.

6-Hydroxydopamine (6-OHDA), a neurotoxic substrate of the dopamine transporter (DAT), is widely used in Parkinson's disease models. However, the molecular mechanisms underlying 6-OHDA's selectivity for dopamine neurons and the injurious sequelae that it triggers are not well understood. We tested whether ectopic expression of DAT induces sensitivity to 6-OHDA in non-dopaminergic rat cortical neurons and evaluated the contribution of voltage-dependent potassium channel (Kv)-dependent apoptosis to the toxicity of this compound in rat cortical and midbrain dopamine neurons. Cortical neurons expressing DAT accumulated dopamine and were highly vulnerable to 6-OHDA. Pharmacological inhibition of DAT completely blocked this toxicity. We also observed a p38-dependent Kv current surge in DAT-expressing cortical neurons exposed to 6-OHDA, and p38 antagonists and Kv channel blockers were neuroprotective in this model. Thus, DAT-mediated uptake of 6-OHDA recruited the oxidant-induced Kv channel dependent cell death pathway present in cortical neurons. Finally, we report that 6-OHDA also increased Kv currents in cultured midbrain dopamine neurons and this toxicity was blocked with Kv channel antagonists. We conclude that native DAT expression accounts for the dopamine neuron specific toxicity of 6-OHDA. Following uptake, 6-OHDA triggers the oxidant-associated Kv channel-dependent cell death pathway that is conserved in non-dopaminergic cortical neurons and midbrain dopamine neurons.

Photoperiod regulates leptin sensitivity in field voles, Microtus agrestis.

We have previously shown that cold-acclimated (8 degrees C) male field voles (Microtus agrestis) transferred from short (SD, 8:16 h L:D) to long photoperiod (LD, 16:8 h L:D) exhibit increases in body mass, adiposity and food intake. To assess whether these increases were associated with decreased leptin sensitivity, we infused LD and SD voles with physiological doses of murine leptin (or saline) delivered peripherally for 7 days via mini-osmotic pumps. Measurements were made of body mass (weight-reducing effect of leptin), food intake (anorectic effect of leptin) and gene expression of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) (thermogenic effect of leptin). The SD animals were sensitive to the weight-reducing effects of leptin (mean body mass decrease of 1.2 g over 7 days) and appetite-reducing effect of leptin (mean food intake decrease of 2.5 g over 7 days), whereas LD voles were resistant to the hormone treatment. The switch from a leptin-sensitive to leptin-resistant state appears to act as a desensitisation mechanism that allows voles transferred from SD to LD to ignore elevated leptin levels generated by increased body fat and accumulate adipose tissue without stimulating compensatory changes opposing the weight gain. Neither SD nor LD voles responded to infusion of leptin by changes in BAT UCP1 gene expression, suggesting dissociation of anorectic and thermogenic effects of leptin, possibly related to chronic cold exposure. Our results indicate that cold-acclimated voles show photoperiod-regulated changes in leptin sensitivity and may provide an attractive model for elucidating molecular mechanisms of leptin resistance.

Effect of photoperiod on body mass, food intake and body composition in the field vole, Microtus agrestis.

Many small mammals respond to seasonal changes in photoperiod by altering body mass and adiposity. These animals may provide valuable models for understanding the regulation of energy balance. Here, we present data on the field vole (Microtus agrestis) - a previously uncharacterised example of photoperiod-induced changes in body mass. We examined the effect of increased day length on body mass, food intake, apparent digestive efficiency, body composition, de novo lipogenesis and fatty acid composition of adipose tissue in cold-acclimated (8 degrees C) male field voles by transferring them from a short (SD, 8 h:16 h L:D) to long day photoperiod (LD, 16 h:8 h L:D). During the first 4 weeks of exposure to LD, voles underwent a substantial increase in body mass, after which the average difference between body masses of LD and SD voles stabilized at 7.5 g. This 24.8% increase in body mass reflected significant increases in absolute amounts of all body components, including dry fat mass, dry lean mass and body water mass. After correcting body composition and organ morphology data for the differences in body mass, only gonads (testes and seminal vesicles) were enlarged due to photoperiod treatment. To meet energetic demands of deposition and maintenance of extra tissue, voles adjusted their food intake to an increasing body mass and improved their apparent digestive efficiency. Consequently, although mass-corrected food intake did not differ between the photoperiod groups, the LD voles undergoing body mass increase assimilated on average 8.4 kJ day(-1) more than animals maintained in SD. The majority (73-77%) of the fat accumulated as adipose tissue had dietary origin. The rate of de novo lipogenesis and fatty acid composition of adipose tissue were not affected by photoperiod. The most important characteristics of the photoperiodic regulation of energy balance in the field vole are the clear delineation between phases where animals regulate body mass at two different levels and the rate at which animals are able to switch between different levels of energy homeostasis. Our data indicate that the field vole may provide an attractive novel animal model for investigation of the regulation of body mass and energy homeostasis at both organism and molecular levels.

Antibiotic use in patients admitted with acute exacerbations of chronic obstructive pulmonary disease.

The objective of this report was to document the pattern of initial antibiotic prescribing in acute exacerbations of chronic obstructive pulmonary disease (COPD) in a hospital setting. All episodes of acute exacerbation of COPD, as diagnosed by the admitting doctor, in one hospital in the period January to May 1996, were identified. Case notes were reviewed retrospectively. Cases of radiographic pneumonia, bronchiectasis and incorrectly coded admissions were excluded. Symptoms, microbial cultures and initial antibiotic therapies were recorded. One hundred and fifty-nine patient episodes were identified; 40 were excluded yielding a sample of 119. Nineteen case notes were unavailable leaving a sample of 100 (84%) episodes. Eighty were treated with antibiotics on admission; amoxycillin was the most frequently prescribed, in 46 (58%) episodes. Of the antibiotic treated group, 42 (53%) patients were given dual therapy, most commonly a macrolide antibiotic with either amoxycillin or a cephalosporin. Intravenous treatment was used in 22 (28%) cases. The duration of intravenous treatment was >48 h in 12 (15%) cases. A total of 76 sputum samples were analysed from 55 patient episodes: 34 (45%) were culture positive. In 15 (27%) patient episodes, antibiotic therapy was changed or instituted on the basis of culture results. These data suggest that antibiotic treatment is not optimal, with overuse of antibiotics, especially intravenous and dual therapy.

Male short-tailed field voles (Microtus agrestis) build better insulated nests than females.

Nest construction is an extremely widespread behaviour. In small endotherms the nest serves primarily to provide insulation, and thereby retard heat loss of the constructor, or its offspring. In arctic and temperate regions many small mammals build nests to protect themselves from low ambient temperatures. We measured the physical properties of nests built by short-tailed field voles Microtus agrestis that were kept in captivity under cold conditions. The most important factor influencing nest insulation was nest wall thickness; however, nests with thick walls also contained more nesting material. Insulative capacity of the nest did not reach an asymptote up to nests containing 20 g of material. Nest insulation was not correlated with resting metabolic rate, body mass or body composition of the vole that constructed the nest. However, nests built by males had greater insulation than those made by females; males also had significantly lower food intake rates when compared to females with nests. No significant difference was observed in either fat mass or whole animal thermal conductance between males and females. Thermal conductance did increase significantly with increasing body mass, although not with resting metabolic rate. Voles with nests for prolonged periods had lower food intakes than voles without nests. The absolute saving averaged 1.9 g and was independent of body mass. This was a 28% saving on intake for a 22-g vole but only an 18% saving for a 40-g individual. When voles had nests for short periods they used the energy they saved to reduce food intake and increase body mass.

An examination of two emergency breathing aids for use during helicopter underwater escape.

BACKGROUND: There is a paucity of published work in which the performance of Emergency Underwater Breathing Aids (EUBA) has been examined in the wide range of scenarios in which helicopter underwater escape may be necessary. In the present investigation two EUBA were examined: the Air Pocket (AP) rebreather and the Short Term Air Supply System (STASS) mini SCUBA set. METHOD: Young, healthy male subjects undertook simple simulated helicopter underwater escapes in water at 15 degrees C and/or 5 degrees C. During the immersions the subjects attempted to remain submerged for 60 s while traversing back and forth along a ladder secured at a depth of 1.25 m. At each temperature the subjects used AP and STASS twice. The subjects were dressed in the Royal Navy winter sea helicopter aircrew equipment assembly and an aircrew helmet. RESULTS: Both AP and STASS significantly extended the underwater survival time of individuals when compared to their maximum breath-hold time (BHT). It is clear from the measurements made of gas concentrations in AP; the volume of air used from STASS; and subjective responses, that the 60-s submersions were achieved more easily with STASS than AP. CONCLUSION: It is concluded that in conditions similar to those of the present experiment STASS will give a longer underwater duration than AP, but this benefit must be offset against the possible risk of pulmonary barotrauma associated with the use of STASS, as well as increased training and maintenance costs. Irrespective of the EUBA which is provided, in-water training, preferably including exposure to cold water, will significantly improve the ability of an individual to use it.

Common ground: the HealthWeb project as a model for Internet collaboration.

The establishment of the HealthWeb project by twelve health sciences libraries provides a collaborative means of organizing and enhancing access to Internet resources for the international health sciences community. The project is based on the idea that the Internet is common ground for all libraries and that through collaboration a more comprehensive, robust, and long-lasting information product can be maintained. The participants include more than seventy librarians from the health sciences libraries of the Committee on Institutional Cooperation (CIC), an academic consortium of twelve major research universities. The Greater Midwest Region of the National Network of Libraries of Medicine serves as a cosponsor. HealthWeb is an information resource that provides access to evaluated, annotated Internet resources via the World Wide Web. The project vision as well as the progress reported on its implementation may serve as a model for other collaborative Internet projects.

Analysis of the use of reference services in an academic health sciences library.

In 1991, the Reference and Information Services staff of the Alfred Taubman Medical Library at the University of Michigan gathered data on the use of the reference desk, including the frequency and types of assistance requested by different user groups throughout the year. Recommendations based on the results of this study led to improved service as well as more efficient use of staff resources.

The effect of leakage on the insulation provided by immersion-protection clothing.

The effect of controlled, incremental water leakage on the thermal insulation provided by three immersion-protection assemblies has been measured using a thermal manikin. The results show an average loss of 30% of the initial insulation for a leak of 500 g, 40% for a leak of 1000 g, and nearly 60% for a leak of 3000 g. The assemblies differed only in the thermal insulation layer which consisted of: A. A single thickness of wool (initial immersed insulation 0.63 clo) B. A double thickness of wool (initial immersed insulation 0.79 clo) and C. A layer of polypropylene batting between nylon covers (initial immersed insulation 0.76 clo). Differences between the assemblies in loss of insulation with leakage were small and no evidence was found to support claims that the insulating properties of polypropylene are more resistant to wetting than those of wool. It is considered that the substantial loss of insulation even with small leaks makes it essential that tests of the water-excluding performance of immersion suits are undertaken in realistic conditions rather than in calm water.

The effect of the UK aircrew chemical defence assembly on thermal strain.

The thermal strain imposed on helicopter aircrew by chemical protective (NBC) clothing in summer in Germany has been assessed in a laboratory simulation. The environmental conditions used were dry bulb temperature 35 degrees C, wet bulb temperature 19 degrees C and a wind speed of 2.0 m X s-1. The NBC equipment imposed a significant thermal strain on the crewman when compared with standard summer flying clothing, but not on the pilot whose tasks involve lower energy expenditures. Deep body temperature exceeded 37.6 degrees C and a significant degree of dehydration (1% of body weight) also occurred, despite the availability of a drinking facility in the respirator. It is recommended that the only practical way of preventing thermal strain in helicopter crewmen under NBC conditions is by providing personal conditioning.

Prediction of oesophageal temperatures from core temperatures measured at other sites in man.

Transient changes in core temperature were induced in seven subjects by immersion in a hot, then a cold, bath and by light intermittent exercise. Measurements of core temperature were made at four sites: the external auditory canal, the oesophagus, the rectum and the gastrointestinal tract. A mathematical model was derived to enable prediction of oesophageal temperature from measurements made at any one of the other sites. The equations for auditory canal and rectal temperatures were very similar to those previously derived in the Institute of Aviation Medicine; use of an equation to predict oesophageal temperatures from gastrointestinal tract temperatures measured in the field using a radio-pill would therefore appear to be reasonable.

Effect of direction and rate of change of deep body and skin temperatures on performance of a rotary pursuit task.

Performance at a pursuit rotor task has been studied during the overshoot of core temperature caused by sudden cooling after heating, and the undershoot caused by sudden heating after cooling. Conditions were chosen so that effects of the absolute levels of core and skin temperature could be discounted. The results showed that the direction of change of core and skin temperature, rates of change of core temperature between -0.07 and +0.06 degrees C/min, and rates of change of skin temperature between -1.0 and +1.0 C/min did not affect performance; particular circumstances of this experiment, expecially the short duration of the changes in direction studied, make this conclusion tentative. Comparison with earlier studies indicates that the major determinants of performance at elevated body temperatures are absolute levels of mean skin temperature, with the absolute level of core temperature having a less significant role.