A 64-channel transmitter for investigating parallel transmit MRI

Multiple channel radiofrequency (RF) transmitters are being used in magnetic resonance imaging to investigate a number of active research topics, including transmit SENSE and B(1) shimming. Presently, the cost and availability of multiple channel transmitters restricts their use to relatively few sites. This paper describes the development and testing of a relatively inexpensive transmit system that can be easily duplicated by users with a reasonable level of RF hardware design experience. The system described here consists of 64 channels, each with 100 W peak output level. The hardware is modular at the level of four channels, easily accommodating larger or smaller channel counts. Unique aspects of the system include the use of vector modulators to replace more complex IQ direct digital modulators, 100 W MOSFET RF amplifiers with partial microstrip matching networks, and the use of digital potentiometers to replace more complex and costly digital-to-analog converters to control the amplitude and phase of each channel. Although mainly designed for B(1) shimming, the system is capable of dynamic modulation necessary for transmit SENSE by replacing the digital potentiometers controlling the vector modulators with commercially available analog output boards. The system design is discussed in detail and bench and imaging data are shown, demonstrating the ability to perform phase and amplitude control for B(1) shimming as well as dynamic modulation for transmitting complex RF pulses.

Bioprocess and bioreactor: next generation technology for production of potential plant-based antidiabetic and antioxidant molecules

Globally, diabetes and obesity are two of the most common metabolic diseases of the 21(st) century. Increasingly, not only adults but children and adolescents are being affected. New approaches are needed to prevent and treat these disorders and to reduce the impact of associated disease-related complications. Industrial-scale production using plant-root cultures can produce quantities and quality of inexpensive bioactive small molecules with nutraceutical and pharmaceutical properties. Using this approach, and targeting these diseases, a next generation approach to tackling this emerging global health crisis may be developed. Adventitious roots cultured in bioreactors under controlled and reproducible conditions have been shown effective for production of natural products. The liquid-phase airlift bioreactor in particular has been used successfully for culturing roots on an industrial-scale and thus may provide an economical production platform for expressing promising plant-based antidiabetic and antioxidant molecules. This review focuses on a next-generation, scalable, bioprocessing approach for adventitious and hairy root cultures that are a pesticide-free, seasonally-independent, plant-based source of three molecules that have shown promise for the therapeutic management of diabetes and obesity: corosolic acid, resveratrol and ginsenosides.

Detection of Borrelia burgdorferi and Borrelia lonestari in birds in Tennessee

Lyme disease in the United States is caused by the bacterial spirochete Borrelia burgdorferi s.s. (Johnson, Schmid, Hyde, Steigerwalt, and Brenner), which is transmitted by tick vectors Ixodes scapularis (Say) and I. pacificus (Cooley and Kohls). Borrelia lonestari, transmitted by the tick Amblyomma americanum L., may be associated with a related syndrome, southern tick-associated rash illness (STARI). Borrelia lonestari sequences, reported primarily in the southeastern states, have also been detected in ticks in northern states. It has been suggested that migratory birds may have a role in the spread of Lyme disease spirochetes. This study evaluated both migratory waterfowl and nonmigratory wild turkeys (Meleagris gallopavo silvestris, Eastern wild turkey) for B. burgdorferi and B. lonestari DNA sequences. A total of 389 avian blood samples (163 migratory birds representing six species, 125 wild turkeys harvested in habitats shared with migratory birds, 101 wild turkeys residing more distant from migratory flyways) were extracted, amplified, and probed to determine Borrelia presence and species identity. Ninety-one samples were positive for Borrelia spp. Among migratory birds and turkeys collected near migration routes, B. burgdorferi predominated. Among turkeys residing further away from flyways, detection of B. lonestari was more common. All A. americanum ticks collected from these areas were negative for Borrelia DNA; no I. scapularis were found. To our knowledge, this represents the first documentation of B. lonestari among any birds.

Estimating the exposure of small mammals at three sites within the Chernobyl exclusion zone--a test application of the ERICA Tool

An essential step in the development of any modelling tool is the validation of its predictions. This paper describes a study conducted within the Chernobyl exclusion zone to acquire data to conduct an independent test of the predictions of the ERICA Tool which is designed for use in assessments of radiological risk to the environment. Small mammals were repeatedly trapped at three woodland sites between early July and mid-August 2005. Thermoluminescent dosimeters mounted on collars were fitted to Apodemus flavicollis, Clethrionomys glareolus and Microtus spp. to provide measurements of external dose rate. A total of 85 TLDs were recovered. All animals from which TLDs were recovered were live-monitored to determine (90)Sr and (137)Cs whole-body activity concentrations. A limited number of animals were also analysed to determine (239,240)Pu activity concentrations. Measurements of whole-body activity concentrations and dose rates recorded by the TLDs were compared to predictions of the ERICA-Tool. The predicted (90)Sr and (137)Cs mean activity concentrations were within an order of magnitude of the observed data means. Whilst there was some variation between sites in the agreement between measurements and predictions this was consistent with what would be expected from the differences in soil types at the sites. Given the uncertainties of conducting a study such as this, the agreement observed between the TLD results and the predicted external dose rates gives confidence to the predictions of the ERICA Tool.

Applications of RF current sources for transmit phased array

Current practice in MRI trends towards higher static magnetic field (B/sub 0/) because of the advantage of signal-to-noise ratio (SNR). However at high magnetic fields, the interaction between a coil and a load becomes significant, thus making current distribution on RF coils disturbed and causing transverse magnetic (B/sub 1/) field inhomogeneity. A novel approach to optimize B/sub 1/, field homogeneity is to use a transmit phased array and adjust the amplitudes and phases of the currents on each element independently. However, independent control is difficult to achieve in conventional arrays due to coupling between elements. In addition, the currents are generally load dependent. In this paper we show that a RF current source is an effective method for controlling the current on each element of the transmit phased array, and that the RF current source is much less sensitive to loading and a interelement coupling than a conventional 50Omega matched coil.

The nonhomologous end joining factor Artemis suppresses multi-tissue tumor formation and prevents loss of heterozygosity

Nonhomologous end joining (NHEJ) is a critical DNA repair pathway, with proposed tumor suppression functions in many tissues. Mutations in the NHEJ factor ARTEMIS cause radiation-sensitive severe combined immunodeficiency in humans and may increase susceptibility to lymphoma in some settings. We now report that deficiency for Artemis (encoded by Dclre1c/Art in mouse) accelerates tumorigenesis in several tissues in a Trp53 heterozygous setting, revealing tumor suppression roles for NHEJ in lymphoid and non-lymphoid cells. We also show that B-lineage lymphomas in these mice undergo loss of Trp53 heterozygosity by allele replacement, but arise by mechanisms distinct from those in Art Trp53 double null mice. These findings demonstrate a general tumor suppression function for NHEJ, and reveal that interplay between NHEJ and Trp53 loss of heterozygosity influences the sequence of multi-hit oncogenesis. We present a model where p53 status at the time of tumor initiation is a key determinant of subsequent oncogenic mechanisms. Because Art deficient mice represent a model for radiation-sensitive severe combined immunodeficiency, our findings suggest that these patients may be at risk for both lymphoid and non-lymphoid cancers.

Overcoming phase effects of voxel-sized coils in planar and cylindrical arrays

Parallel imaging in MRI (using multiple coils to partially encode k-space) is currently the primary route to decreasing scan time. Single echo acquisition (SEA) imaging is a completely parallel imaging method recently developed by our group that collects a full image in a single echo. Phase encoding is eliminated and replaced by the spatial localization of long and very narrow coils. The fact that the coils are on the order of the voxel size for the first time in an MR application has led to an examination of the effect of the phase of the coil on the signal received from the voxel and how to most effectively manipulate it. Obtaining full signal from a voxel in planar arrays can be accomplished with a single gradient compensation pulse, but the phase effects in cylindrical arrays are more complex due to the changing coil angle with regard to the Cartesian axes of the gradients. This paper discusses the signal-phase interactions of planar and cylindrical arrays of voxel-sized coils and suggests methods for phase manipulation for optimization.

"Blind" testing of models for predicting the 90Sr activity concentration in river systems using post-Chernobyl monitoring data

Two different models for predicting the time-dependent mobility of (90)Sr in river systems have been evaluated using post-Chernobyl monitoring data for five large Belarusian rivers (Dnieper, Pripyat, Sozh, Besed and Iput) in the period between 1990 and 2004. The results of model predictions are shown to be in good agreement (within a factor of 5) with the measurements of (90)Sr activity concentration in river waters over a long period of time after the accident. This verifies the relatively good accuracy of the generalised input parameters of these models which were derived primarily from measurements of (90)Sr deposited after atmospheric nuclear weapons testing (NWT). For the cases studied here, the simpler AQUASCOPE model performed just as well as the more complex "Global" model which used GIS-based catchment data as an input. The reasons for this are discussed. Exponential decay equations were also curve-fitted to the data for each river to help assess the uncertainties in the predictive models.

Factors contributing to radiocaesium variability in upland sheep flocks in west Cumbria (United Kingdom)

Following the Chernobyl accident in 1986, restrictions were placed on the movement and slaughter of sheep within upland areas of the UK because radiocaesium activity concentrations in their meat exceeded 1000 Bq kg(-1) fresh weight. Some farms remain under restriction in 2007. From 1991 to 1993 detailed studies were conducted on three sheep farms within the restricted area of west Cumbria to systematically assess the various parameters which may contribute to the observed variability in radiocaesium activity concentrations within sheep flocks. This paper reports the spatial variation in soil and vegetation activity concentrations across the grazed areas at these farms and determines the influence of grazing behaviour on variability in (137)Cs activity concentrations between individual sheep within the flocks. Together with previously reported results, these new data are used to draw conclusions on the factors determining variability within the three flocks. However, the factors are too site specific to be able to generalise the findings to other farms within the restricted areas of the UK.

Prediction of spatial variation in global fallout of 137Cs using precipitation

Deposition from atmospheric nuclear weapons tests (termed global fallout) has been shown to be proportional to the rate of precipitation. Here we describe methods for using precipitation and radionuclide deposition information for a reference site to estimate global fallout at other locations. These methods have been used to estimate global fallout in Iceland, identified during the Arctic Monitoring and Assessment Programme (AMAP) by Wright et al. [Wright, S.M., Howard, B.J., Strand, P., Nylén, T., Sickel, M.A.K., 1999. Prediction of 137Cs deposition from atmospheric nuclear weapons tests within the Arctic. Environ Pollut 104, 131-143.] as one of the Arctic areas which received the highest global fallout, but where measurements of contamination were sparse, and difficult to obtain due to the remote and inaccessible terrain of much of the country. Measurements of global fallout 137Cs deposition have been made in Iceland at sites close to meteorological stations to ensure that precipitation data were of high quality. The AMAP modeling approach, based on measured precipitation and radionuclide deposition data, was applied using a reference monitoring station located close to Reykjavik. The availability of good precipitation data and locally based estimates of time dependent ratios of 137Cs deposition to precipitation during the fallout period gave a better correlation between predicted and measured 137Cs global fallout (r2=0.96) than that achieved using the much more heterogeneous set of data collected by AMAP over the whole of the Arctic. Having obtained satisfactory results with the model for a number of calibration sites alongside meteorological stations we then produced a map of estimated 137Cs deposition based on a model of estimated precipitation. This deposition map was then successfully validated (r2=0.85) for sites where 137Cs deposition was measured; the associated uncertainty in predictions was also estimated.

Putative contributors to the secular increase in obesity: exploring the roads less traveled

OBJECTIVE

To investigate plausible contributors to the obesity epidemic beyond the two most commonly suggested factors, reduced physical activity and food marketing practices.

DESIGN

A narrative review of data and published materials that provide evidence of the role of additional putative factors in contributing to the increasing prevalence of obesity.

DATA

Information was drawn from ecological and epidemiological studies of humans, animal studies and studies addressing physiological mechanisms, when available.

RESULTS

For at least 10 putative additional explanations for the increased prevalence of obesity over the recent decades, we found supportive (although not conclusive) evidence that in many cases is as compelling as the evidence for more commonly discussed putative explanations.

CONCLUSION

Undue attention has been devoted to reduced physical activity and food marketing practices as postulated causes for increases in the prevalence of obesity, leading to neglect of other plausible mechanisms and well-intentioned, but potentially ill-founded proposals for reducing obesity rates.

Patterns and inventories of radioactive contamination of island sites of the Yenisey River, Russia

The distribution of radioactive contamination at three island sites downstream from the Krasnoyarsk Mining and Chemical Combine (KMCC) was studied with the objectives of mapping contamination levels, interpreting radionuclide distributions through consideration of alluvial processes and determining radionuclide inventories. Contamination was measured using in situ gamma spectrometry and landforms characterised using topographic surveying methods. Maximum (137)Cs contamination densities (700 kBq m(-2)) were found on low- and middle-level floodplains and low-lying interconnecting areas of Beriozovy Island (16 km from the KMCC). On Mikhin Island (180 km from the KMCC) maximum total (60)Co, (152)Eu and (154)Eu activity concentrations (30-40 kBq m(-2)) occur in low-lying areas inundated during flooding. Maximum (137)Cs and total (60)Co, (152)Eu and (154)Eu contamination densities on Cheriomukhov Island (250 km from the KMCC) were 390 and 50 kBq m(-2), respectively. Estimated (137)Cs inventories were 145, 148 and 16GBq for Beriozovy, Mikhin and Cheriomukhov Islands, respectively.

Development of a case report review instrument

Case reports are valued components of the medical literature. The assessment of case reports by editors of medical journals and peer reviewers is largely subjective. The purpose of this study was to develop a reliable instrument to evaluate the quality of written case reports. Instrument development involved review of the literature and the materials provided to peer reviewers who review manuscripts, communications with journal editors and discussions of the study team. After multiple amendments, the instrument was pilot tested on both published and unpublished case reports. Further revisions resulted in the final 11-item tool. Four independent reviewers evaluated 28 case reports in their original submission format that had been submitted to five medical journals. The reviewers were blinded to the specific journal that the manuscripts had been submitted and to whether the case reports had been accepted for publication. Inter-rater reliability was assessed using multirater kappa. Inter-rater reliability ranged from 0.03 to 0.90. The four variables with the highest agreement between raters were (i) rationale for writing the case report; (ii) implications of the case report; (iii) adequacy of the literature review; and (iv) overall impression about whether to accept or reject the manuscript (kappas of 0.67, 0.67, 0.90 and 0.67, respectively). Six of the instrument's first 10 variables were highly correlated with the reviewers' decision about whether to accept or reject the case report for publication (item 11) (all p < 0.001). No correlation existed between the reviewers' decision to accept or reject the manuscript and the actual decision that had been made by the various journals. The case report review instrument is the first such tool for objectively evaluating case reports and appears to have reasonable reliability. Medical journals may wish to incorporate the use of this instrument into the decision making about a case report's suitability for publication.

Long-term consequences for Northern Norway of a hypothetical release from the Kola nuclear power plant

The spatial and temporal variation in radiocaesium and (90)Sr doses to two population groups of the two Northernmost counties of Norway, Troms and Finnmark, following a hypothetical accident at the Kola nuclear power plant (KNPP) have been estimated using a model implemented within a geographical information system. The hypothetical accident assumes a severe loss of coolant accident at the KNPP coincident with meteorological conditions causing significant radionuclide deposition in the two counties. External doses are estimated from ground deposition and the behaviour of the different population groups, and internal doses from predicted food product activity concentrations and dietary consumption data. Doses are predicted for reindeer keepers and other Norwegian inhabitants, taking account of existing (137)Cs and (90)Sr deposition but not including the remedial effect of any countermeasures that might be used. The predicted doses, arising mainly from radiocaesium, confirm the Arctic Monitoring and Assessment Programme assessment that residents of the Arctic are particularly vulnerable to radiocaesium contamination, which could persist for many years. External doses are predicted to be negligible compared to ingestion doses. Ingestion doses for reindeer keepers are predicted to exceed 1 mSv y(-1) for several decades primarily due to their high consumption of reindeer meat. Other Norwegians would also be potentially exposed to doses exceeding 1 mSv y(-1) for several years, especially if they consume many local products. Whilst reindeer production is the most important exposure pathway, freshwater fish, lamb meat, dairy products, mushrooms and berries are also significant contributors to predicted ingestion doses. Radionuclide fluxes, defined as the total output of radioactivity in food from an area for a unit time, are dominated by reindeer meat. The results show the need for an effective emergency response, with appropriate countermeasures, should an accident of the scale considered in this paper occur at the KNPP.

Radiocaesium in lynx in relation to ground deposition and diet

The European lynx (Lynx lynx) might be expected to have a high intake of radiocaesium in the parts of Sweden where the main prey of the lynx, namely reindeer and roe deer, have high activity concentrations of radiocaesium because of high ground deposition. We have measured (137)Cs in muscle samples from 733 lynx during 1996-2003. The aim was to quantify the extent to which radiocaesium is transferred from fallout deposition to lynx, to test whether the transfer was higher in areas where there are reindeer present, to see if there was any decline in radiocaesium over time, and to calculate the radiation dose to lynx. Most samples were collected in central and northern Sweden during January-April. Activity concentrations in lynx varied from 13 Bq kg(-1) to about 15 kBq kg(-1) fresh weight, with the highest value corresponding to a radiation dose at 18 mGy/year. Aggregated transfer coefficients (Tag), calculated by dividing the (137)Cs activity concentration in lynx muscle by the average ground deposition (total from Chernobyl and nuclear weapon tests) within a 50 km radius around the location of the lynx, varied from 0.004 to 1.3 m(2) kg(-1) and were significantly higher within the reindeer herding area than outside. The concentration ratio (CR) for lynx/reindeer was 2.6 on average, whilst the average for lynx/roe deer outside the reindeer herding area was lower at 1.3. Based on these results, a CR of around 2 could be considered representative for the general ratio between predator and prey. A long-term decline of radiocaesium in prey species was reflected in lynx, with an effective half-life of 7 years from 1996 to 2003. The study shows that the accumulation of radiocaesium in predators, especially predators of reindeer, makes them more vulnerable to high radiocaesium deposition than most other wild species.

Monte-Carlo prediction of changes in areas of west Cumbria requiring restrictions on sheep following the Chernobyl accident

Following the 1986 Chernobyl accident radiocaesium levels in sheep meat in some upland areas of the United Kingdom were above the national intervention limit. West Cumbria was one of these areas and restrictions are currently still in place. In addition to deposition from the Chernobyl accident, Cumbria has been subject to radiocaesium deposition from atmospheric nuclear weapons tests, the 1957 Windscale accident and routine releases from the Sellafield nuclear reprocessing plant. A Monte-Carlo approach has been used to try to predict areas in west Cumbria where radiocaesium activity concentrations in lamb meat would require the imposition of restrictions at different times after the Chernobyl accident. The approach models the transfer of radiocaesium from soil to vegetation, based upon soil organic matter, and from vegetation to lamb meat. Spatial inputs are soil organic matter and total post-Chernobyl (137)Cs and (134)Cs deposition; a ratio of Chernobyl (137)Cs to (134)Cs deposition has been used to differentiate Chernobyl and pre-Chernobyl (137)Cs deposition. Comparisons of predicted radiocaesium transfer from soil-vegetation and the spatial variation in lamb (137)Cs activity concentrations are good and predicted restricted areas with time after Chernobyl compare well to the restricted areas set by UK government. We predict that restrictions may be required until 2024 and that in some areas the contribution of pre-Chernobyl (137)Cs to predicted lamb radiocaesium activity concentrations is significant, such that restrictions may only have been required until 1994 as a consequence of Chernobyl radiocaesium deposition alone. This work represents a novel implementation of a spatial radioecological model using a Monte-Carlo approach.

Detection of Borrelia lonestari in Amblyomma americanum (Acari: Ixodidae) from Tennessee

Genetic sequences characteristic of Borrelia lonestari (Barbour et al. 1996) were detected in two pools of adult Amblyomma americanum (L.) from Tennessee, corresponding to an estimated minimum field infection rate of 8.4 infected ticks/1000 adults. DNA amplification was conducted using primers derived from the B. lonestari flagellin gene that would also amplify Borrelia burgdorferi (Johnson, Schmid, Hyde, Steigerwalt, and Brenner). Species-specific, internal probes were then used to differentiate between genetic sequences of the spirochetes. Subsequent nucleotide sequencing confirmed the presence of B. lonestari in A. americanum; B. burgdorferi was not detected. This represents the first report of B. lonestari from Tennessee, and suggests that Lyme-like illness may occur in Tennessee.

Electrospray ionisation mass spectrometric analysis of lipid restructuring in the carp (Cyprinus carpio L.) during cold acclimation

Cold acclimation of carp from 30°C to 10°C causes a restructuring of liver microsomal phospholipids characterised by increased proportions of monounsaturated fatty acid in phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Here, we have used electrospray ionisation mass spectrometry (ESI-MS) to determine the patterns of alteration to individual molecular species compositions of PC, PE and phosphatidylinositol (PI) in response to gradually decreasing temperature. The results demonstrate that cold induces precise changes to a limited number of phospholipid species, and that these changes are distinct and different for each phospholipid class. The major change for PC was increased 16:1/22:6, but for PE the species that increased was 18:1/22:6. By contrast, the PI species that increased during cold acclimation were characterised by an sn-1 monounsaturated fatty acid in combination with arachidonoyl or eicosapentaenoyl fatty acid at the sn-2 position. Analysis of acyl distribution indicates that cold only caused the accumulation of monounsaturated fatty acids at the sn-1 and not at the sn-2 position of phospholipids. These results highlight the tight and restricted range of modifications that membranes make to their phospholipid composition in response to thermal stress.

Bovine immunodeficiency virus expression in vitro is reduced in the presence of beta-chemokines, MIP-1alpha, MIP-1beta and RANTES

The inhibition of HIV expression in vitro by a cocktail of the beta-chemokines MIP-1alpha, MIP-1beta and RANTES provided the initial evidence that HIV utilizes chemokine receptors as co-receptors for infection of cells. Bovine immunodeficiency virus (BIV), a lentivirus, infects a wide variety of leukocyte populations, but the cellular receptor(s) utilized by this virus for infection of cells is not known. The purpose of this study was to determine whether MIP-1alpha, MIP-1beta and RANTES affect BIV expression in vitro, as a prelude to identifying the cellular receptors utilized by this virus. Fetal bovine lung (FBL) cells were pretreated with serial dilutions of a cocktail of the chemokines, and then the cells were infected with BIV. Virus expression in these cells was determined by counting the syncytia that had developed in the cultures by five days after infection. A significant decrease in syncytium formation, corresponding to increasing concentrations of the chemokines, was the result. Reacting the chemokines with chemokine-specific neutralizing antibodies prior to treatment of the cells neutralized the effect of the chemokines on virus replication in a dose-dependent manner, restoring viral expression to a level similar to that of untreated cells. The presence of a CCR5 homologue on the surface of FBL cells was confirmed using an anti-CCR5 monoclonal antibody and FACS analysis. Collectively, these data provide preliminary evidence that BIV may utilize the CCR5 receptor for infection of cells in vitro, but additional studies are necessary to confirm this.

Estimation of critical loads for radiocaesium in Fennoscandia and Northwest Russia

The application of the critical loads methodology for radioactive contamination of Arctic and sub-arctic ecosystems, where natural and semi-natural food products are important components of the diet of many people, is proposed and discussed. The critical load is herein defined as the amount of radionuclide deposition necessary to produce radionuclide activity concentrations in food products exceeding intervention limits. The high transfer of radiocaesium to reindeer meat gives this product the lowest critical load, even though the intervention limit is relatively high compared with other products. Ecological half-lives of radiocaesium in natural and semi-natural products are often very long, and it is therefore important to take account of contamination already present in the event of an accident affecting areas where such products are important. In particular, the long ecological half-life for radiocaesium in moose meat means that the critical load is highly sensitive to prior deposition. An example of the potential application of the method for emergency preparedness is given for the Chernobyl accident.

Predictions of in situ solid/liquid distribution of radiocaesium in soils

Previous work has demonstrated that plant uptake of radiocaesium (RCs) is related to the activity concentration of RCs in soil solution, which is linked to the soil/soil solution distribution coefficient, K(D). The solid-liquid distribution of RCs is generally studied in soil suspensions in the laboratory and there are few reported measurements for in situ soil solutions. From a data set of 53 different soils (contaminated with either 134CsCl or 137CsCl) used in pot trials to investigate grass uptake of RCs, we analysed the variation of in situ K(D) with measured soil properties. The soils differed widely in % clay (0.5-58%), organic matter content (1.9-96%) and pH (2.4-7.0, CaCl2). The K(D) varied between 29 and 375,000 L kg-' (median 1460 L kg(-1)). Stepwise multiple regression analysis showed a significant correlation between the log K(D) and pH (p < 0.001), log %clay (p < 0.01) and log exchangeable K (p < 0.001) (overall R2 = 0.70). The in situ K(D) values were further compared to K(D)S predicted using an existing model, which assumes that RCs sorption occurs on specific sites and regular ion-exchange sites on the soil solid phase. Sorption of RCs on specific sites was quantified from the radiocaesium interception potential (RIP) measured for each soil and the soil solution concentrations of K+ and NH4+. The in situ log K(D) correlated well with the predicted K(D) (R2 = 0.85 before plant growth, R2 = 0.83 after plant growth). However, the observations were fivefold to eightfold higher than the predictions, particularly for the mineral soils. We attribute the under-prediction to the long contact times (minimum 4 weeks) between the RCs tracers and our experimental soils relative to the short (24 h) contact times used in RIP measurements. We conclude that our data confirmed the model but that ageing of RCs in soil is a factor that needs to be considered to better predict in situ KD values.

Effect of origin of radiocaesium on the transfer from fallout to reindeer meat

Data on radiocaesium contamination of reindeer from five regions in Sweden have been used, together with interpolated radiocaesium deposition data, to quantify spatial variation in transfer to reindeer meat and to consider how it changes with time in different areas. Since the regions were contaminated to different extents by global and Chernobyl fallout, it was also possible to determine the influence of the origin or age of radiocaesium fallout on the transfer to reindeer meat. The regions differed significantly with regard to transfer of radiocaesium to reindeer meat. In two regions in the North of Sweden, where there was less Chernobyl 137Cs, aggregated transfer coefficients (Tag), estimated for the main slaughter period in the first year after the Chernobyl fallout, were low (0.15 and 0.36 m2 kg(-1) in January-April). Average Tag values calculated for the winter period (January-April) in two regions in the middle of Sweden, where deposition from Chernobyl dominated (83 and 94%, respectively, of the total deposition), were 0.78 and 0.84 m2 kg(-1), respectively with a maximum Tag for an individual reindeer of 1.87 m2 kg(-1). There was a threefold increase in Tag values from early autumn to late winter reflecting the change in the reindeer diet from less contaminated vascular plants to more contaminated lichens. The decline of 137Cs in reindeer meat from 1986 to 2000 differed between regions with longer effective half-lives (Tef) in the northerly regions (11.0 and 7.1 years, respectively) with less Chernobyl fallout, and shorter half-lives in the other three regions (3.5-3.8 years). This observation, together with a lack of a decline in early autumn in the region with least Chernobyl fallout, supports the theory of a gradual, but reversible, fixation of radiocaesium in the soil over the mid-long term. The results suggest that both the extent of transfer of 137Cs to reindeer meat, and its subsequent decline with time, are affected by the differing origins of radiocaesium and that previous contamination may substantially influence radiocaesium transfer in the event of a further accident.

Which values do attending physicians try to pass on to house officers?

CONTEXT

Professional development in medicine includes the acquisition of values and attitudes which are fundamental to the role of the physician. Little is known about which values and attitudes attending physicians emphasize in their teaching of medical trainees to help them develop professionally.

OBJECTIVE

To determine the values and attitudes which attending physicians try to pass on to residents in order to encourage their professional development.

DESIGN

Cross-sectional study using a mailed survey.

SETTING

Four university-affiliated teaching hospitals.

SUBJECTS

Attending physicians with residency-level teaching responsibilities.

MEASUREMENTS

The self-reported single value or attitude that attending physicians try to pass on to house officers.

RESULTS

Of the 341 attending physicians who returned a completed questionnaire, 265 (78%) shared the single value or attitude they try to pass on to residents. The four main categories into which more than 95% of responses could be categorized were: (i) caring, (ii) respect, (iii) communication and (iv) integrity. There were no statistically significant differences between the responses given by attending physicians who had been named as excellent role models and their colleagues who had not been so named.

CONCLUSIONS

Attending physicians attempt to pass on values and attitudes they consider important for the professional development of medical trainees. Future research might focus on optimal ways to teach these qualities to medical learners.

Multi-channel magnetic resonance spectroscopy through time domain multiplexing

Time domain multiplexing (TDM) is presented as a viable approach to increasing the sensitivity and efficiency of magnetic resonance spectroscopic (MRS) experiments through multi-channel signal acquisition. By switching very rapidly between coils of a receive phased array, TDM receiver extensions allow the acquisition of multiple, independent spectra through a single channel magnetic resonance console. A TDM receiver extension designed for imaging and spectroscopy is described, and the impact of this hardware extension on the processing and quantitation of MRS data is addressed. The primary complication involves the use of fixed bandwidth RF band-pass filters that can not be adjusted to match the spectral width of the desired MRS experiment.MRS sequences whose bandwidths are narrower than the bandwidth provided by TDM band-pass filters can be acquired through TDM with minimal loss of SNR as long as two constraints are met. The first constraint requires that the entire bandwidth of the band-pass filters be sampled at or more rapidly than the Nyquist rate associated with their bandwidth, to prevent extra noise from aliasing into the final spectrum. The second requirement is that spectral resolution be held constant to that of the desired experiment. Results from a two-channel multiplexed MRS experiment, conducted according to these guidelines, illustrate that TDM can be used to allow acquisition of multi-channel MRS experiments through single channel console systems with a minimal loss in SNR.

A sixteen-channel multiplexing upgrade for single channel receivers

With the increasing interest in phased arrays in magnetic resonance imaging, imaging system receivers capable of acquiring larger number of parallel signals are needed. Suggested techniques for rapid imaging propose the use of arrays with as many as 128 elements. While simply duplicating the number of receiver chains as needed is a viable technique, it quickly becomes both cumbersome and expensive. Time domain multiplexing offers an alternative solution to this problem. By using RF multiplexing switches, a single receiver can be upgraded to an array receiver capable of multi-channel data acquisition giving users array capability. Additionally, it can be used to dramatically increase acquisition capability of multiple receiver systems. This paper reports results from a multiplexing system upgrade, which converts a single channel standard clinical imaging system to a 16-channel array system. The upgrade includes both the RF multiplexing front-end and an external data acquisition system with image processing capability. Issues concerning the implementation of high channel-count multiplexers are also discussed.

Temporal and spatial prediction of radiocaesium transfer to food products

A recently developed semi-mechanistic temporal model is used to predict food product radiocaesium activity concentrations using soil characteristics available from spatial soil databases (exchangeable K, pH, percentage clay and percentage organic matter content). A raster database of soil characteristics, radiocaesium deposition, and crop production data has been developed for England and Wales and used to predict the spatial and temporal pattern of food product radiocaesium activity concentrations (Bq/kg). By combining these predictions with spatial data for agricultural production, an area's output of radiocaesium can also be estimated, we term this flux (Bq/year per unit area). Model predictions have been compared to observed data for radiocaesium contamination of cow milk in regions of England and Wales which received relatively high levels of fallout from the 1986 Chernobyl accident (Gwynedd and Cumbria). The model accounts for 56% and 80% of the observed variation in cow milk activity concentration for Gwynedd and Cumbria, respectively. Illustrative spatial results are presented and suggest that in terms of food product contamination areas in the North and West of England and Wales are those most vulnerable to radiocaesium deposition. When vulnerability is assessed using flux the spatial pattern is more complex and depends upon food product.

Racial differences in outcomes of veterans undergoing percutaneous coronary interventions

BACKGROUND

In the era of stenting relatively little is known about racial differences in the outcomes of percutaneous interventions (PCI). The purpose of this study was to determine whether there were racial differences with respect to short- and long-term outcomes in veterans undergoing PCI.

METHODS

We used the national Department of Veterans Affairs (VA) patient treatment file to identify 24,625 African American and white veterans who had PCI in VA medical centers between October 1, 1994, and September 30, 1999. Baseline demographic characteristics were obtained, as was a measure of comorbidity. Short-term outcomes included hospital mortality and same-admission coronary artery bypass surgery, and long-term outcomes were vital status and rehospitalization. Multivariate statistical methods were used to adjust for patient differences when comparing both short- and long-term outcomes for African American and white veterans.

RESULTS

African Americans were 11% of veterans, and in comparison with their white counterparts had more hypertension, diabetes, and acute myocardial infarction. African Americans less often underwent stenting (44% vs 49%), although hospital mortality (2.0% vs 1.9%) and same-admission bypass surgery (1.9% vs 2.2%) rates were similar. Two-year survival was 89% in African Americans and 91% in white veterans (P =.0014), and after adjustment for covariates African Americans had slightly higher mortality rates (hazard ratio 1.11, 95% confidence interval 1.05-1.17). At 2 years almost 61% of both African American and white veterans were rehospitalized for any reason.

CONCLUSION

Short- and long-term outcomes for African American and white veterans undergoing PCI in VA medical centers were similar, although African Americans underwent stenting less often.

Personal growth in medical faculty: a qualitative study

BACKGROUND

A physician's effectiveness depends on good communication, and cognitive and technical skills used with wisdom, compassion, and integrity. Attaining the last attributes requires growth in awareness and management of one's feelings, attitudes, beliefs, and life experiences. Yet, little empiric research has been done on physicians' personal growth.

OBJECTIVE

To use qualitative methods to understand personal growth in a selected group of medical faculty.

DESIGN

Case study, using open-ended survey methods to elicit written descriptions of respondents' personal growth experiences.

SETTING

United States and Great Britain.

PARTICIPANTS

Facilitators, facilitators-in-training, and members of a personal growth interest group of the American Academy on Physician and Patient, chosen because of their interest, knowledge, and experience in the topic area and their accessibility.

MEASUREMENTS

Qualitative analysis of submitted stories included initially identifying and sorting themes, placing themes into categories, applying the categories to the database for verification, and verifying findings by independent reviewers.

RESULTS

Of 64 subjects, 32 returned questionnaires containing 42 stories. Respondents and nonrespondents were not significantly different in age, sex, or specialty. The analysis revealed 3 major processes that promoted personal growth: powerful experiences, helping relationships, and introspection. Usually personal growth stories began with a powerful experience or a helping relationship (or both), proceeded to introspection, and ended in a personal growth outcome. Personal growth outcomes included changes in values, goals, or direction; healthier behaviors; improved connectedness with others; improved sense of self; and increased productivity, energy, or creativity.

CONCLUSIONS

Powerful experiences, helping relationships, and introspection preceded important personal growth. These findings are consistent with theoretic and empiric adult learning literature and could have implications for medical education and practice. They need to be confirmed in other physician populations.

Contribution of a lecturer-practitioner in implementing evidence-based health care

This article describes and discusses the role of a lecturer-practitioner (LP) in the context of a university and practice development unit within a primary care trust in contributing to evidence-based health care. Evidence-based health care is currently high on the political and professional agendas. Methods employed in practice to create an environment that encourages and supports innovation will be described. Methods used in the educational establishment will also be highlighted from a theoretical and practice perspective. Progress to date and expected future outcomes will be shared. The article concludes that progress is dependent on all those involved, sharing common goals in the implementation of evidence based health care as it will continue to remain high on the agenda in the educational and service sectors. This drive towards clinical effectiveness and evidence based practice puts the LP in an ideal position to reduce the practice-theory gap by the nature of their integrated role.

The challenge of problem residents

Internal medicine residency training is demanding and residents can experience a wide variety of professional and personal difficulties. Residency programs everywhere have had and will continue to have problem residents. Training programs should be equipped to effectively identify and manage residents who experience problems. Previous articles that have been published on the topic of problem residents primarily addressed concerns such as impairment due to depression and substance abuse. The content of this article is derived from a comprehensive review of the literature as well as other data sources such as interviews with program directors and workshops at national professional meetings. This article focuses primarily on four issues related to problem residents: their identification, underlying causes, management, and prevention. The study attempts to be evidence-based, wherever possible, highlighting what is known. Recommendations based on the synthesis of the data are also made. Future ongoing studies of problem residents will improve our understanding of the matters involved, and may ultimately lead to improved outcomes for these trainees.

Comparison of outcomes of coronary stenting versus conventional coronary angioplasty in the department of veterans affairs medical centers

Although the short-term benefits of stent deployment have been established, less is known about long-term outcomes. This study compares short- and long-term outcomes in veterans undergoing stenting and conventional coronary angioplasty. We used Department of Veterans Affairs databases to identify 27,224 veterans who had undergone percutaneous coronary intervention (PCI) in Veterans Affairs medical centers between October 1994 and September 1999. Patients were classified according to whether they had acute myocardial infarction (AMI) as the principal diagnosis. Baseline characteristics were similar in the stent and conventional groups. In AMI, hospital mortality was 2.9% for those with stents and 4.8% for those who underwent conventional coronary angioplasty (p <0.0001), whereas for patients without AMI, hospital mortality was similar (1.2% vs 1.4%, p = 0.12). For AMI, same-admission bypass surgery rates were lower in the stent group (0.7% vs 3.2%, p <0.0001) and in the group without AMI (1.2% vs 3.3%, p <0.0001). Two-year survival was better for stenting in veterans with (90% vs 88%, p = 0.006) and without (92% vs 91%, p = 0.008) AMI. For AMI, 2-year rehospitalization rates for PCI (10% vs 13%, p <0.0001), coronary artery bypass surgery (4% vs 6%, p <0.0001), and unstable angina (17% vs 23%) were lower for those who had stenting. In the no-AMI group, 2-year rehospitalization rates for PCI (14% vs 17%, p <0.0001), coronary artery bypass surgery (5% vs 8%, p <0.0001), and unstable angina (22% vs 29%, p <0.0001) were lower in the stent group. Veterans who underwent stenting had lower hospital mortality, reduced rates of same-admission bypass surgery, marginally better survival, and lower rates of rehospitalization than their counterparts who had conventional coronary angioplasty.

Teaching resource and information management using an innovative case-based conference

Physicians play a critical role in controlling resource use in medicine. This paper describes an innovative, interdisciplinary conference that teaches housestaff and medical students about resource and information management in the hospital setting. The objectives are to help foster communication between physicians and other members of the health care team, to improve the understanding of hospital reimbursement, and to influence attitudes toward practicing cost effectiveness. The conference structure includes the following components: case presentation by the treating physician and follow-up information provided by the primary care physician, a review of the itemized hospital bill, discussion of coding issues, discussion of hospital reimbursement comparing case data to institutional and state averages, and a summary of key take-home points and lessons.

Physician opinion about electronic publications

PURPOSE

Many medical journals are currently offering physicians the option to subscribe electronically, allowing readers access by means of the Internet. However, physicians' opinions about this innovation are not known. This exploratory study was designed to learn more about physicians' opinions and attitudes regarding electronic publications.

SUBJECTS AND METHODS

A three-page questionnaire was developed to survey all physicians (faculty and house officers) at a large university-affiliated teaching hospital in Baltimore, Maryland. The questionnaire explored many of the features that make electronic journals distinct from printed journals.

RESULTS

Of the 314 physicians surveyed, 255 (81%) returned a completed questionnaire. The mean (+/- SD) age of the respondents was 41 +/- 10 years, 164 (65%) were male, and 50 (20%) were house officers. Twenty-six percent of respondents (n = 66) thought that electronic journals would lower the quality of the medical literature, and 25% (n = 63) believed that the prestige of authorship would be lessened. Seventy to eighty percent of physicians responded that electronic journals would decrease clutter in their offices and homes, be more environmentally friendly than the current system, make it easier to locate research reports that they had read, and offer the benefit of linkage to related articles. Seventy-four percent of physicians (n = 188) were concerned about losing the convenience of being able to read a printed journal anywhere. In multivariate analyses, female sex, being a faculty member (vs house officer), fewer publications, better computer skills, and more frequent use of the Internet were independently associated with positive attitudes toward various aspects of electronic journals.

CONCLUSIONS

Physicians responded favorably to the many potential values and applications of electronic publications but were most concerned with the loss of the convenience that printed journals offer.

Self-help countermeasure strategies for populations living within contaminated areas of Belarus, Russia and Ukraine

Countermeasures have been effectively employed within intensive agricultural systems in areas of the Former Soviet Union (FSU) affected by the Chernobyl accident. However, ingestion doses continue to be elevated in some areas as a result of few foodstuffs which are collected from the wild or produced by the household. Forest fungi and berries, and milk from privately owned cattle are the most notable contributors to 137Cs intakes amongst these foodstuffs. In this paper we consider advice which would help affected populations to both understand the importance of these exposure routes and to reduce their exposure. In addition to the potential radiological benefits, self-help schemes are highly cost-effective and likely to have a positive psychological influence on populations living within contaminated areas of the FSU. Evidence to suggest that the transfer of radiocaesium to cow milk is considerably higher in the FSU than within western Europe and North America is discussed.

Predicting the transfer of radiocaesium from organic soils to plants using soil characteristics

A model predicting plant uptake of radiocaesium based on soil characteristics is described. Three soil parameters required to determine radiocaesium bioavailability in soils are estimated in the model: the labile caesium distribution coefficient (kd1), K+ concentration in the soil solution [mK] and the soil solution-->plant radiocaesium concentration factor (CF, Bq kg-1 plant/Bq dm-3). These were determined as functions of soil clay content, exchangeable K+ status, pH, NH4+ concentration and organic matter content. The effect of time on radiocaesium fixation was described using a previously published double exponential equation, modified for the effect of soil organic matter as a non-fixing adsorbent. The model was parameterised using radiocaesium uptake data from two pot trials conducted separately using ryegrass (Lolium perenne) on mineral soils and bent grass (Agrostis capillaris) on organic soils. This resulted in a significant fit to the observed transfer factor (TF, Bq kg-1 plant/Bq kg-1 whole soil) (P < 0.001, n = 58) and soil solution K+ concentration (mK, mol dm-3) (P < 0.001, n = 58). Without further parameterisation the model was tested against independent radiocaesium uptake data for barley (n = 71) using a database of published and unpublished information covering contamination time periods of 1.2-10 years (transfer factors ranged from 0.001 to 0.1). The model accounted for 52% (n = 71, P < 0.001) of the observed variation in log transfer factor.

Altered airway surfactant phospholipid composition and reduced lung function in asthma

Pulmonary surfactant in bronchoalveolar lavage fluid (BALF) and induced sputum from adults with stable asthma (n = 36) and healthy controls (n = 12) was analyzed for phospholipid and protein compositions and function. Asthmatic subjects were graded as mild, moderate, or severe. Phospholipid compositions of BALF and sputum from control subjects were similar and characteristic of surfactant. For asthmatic subjects, the proportion of dipalmitoyl phosphatidylcholine (16:0/16:0PC), the major phospholipid in surfactant, decreased in sputum (P < 0.05) but not in BALF. In BALF, mole percent 16:0/16:0PC correlated with surfactant function measured in a capillary surfactometer, and sputum mole percent 16:0/16:0PC correlated with lung function (forced expiratory volume in 1 s). Neither surfactant protein A nor total protein concentration in either BALF or sputum was altered in asthma. These results suggest altered phospholipid composition and function of airway (sputum) but not alveolar (BALF) surfactant in stable asthma. Such underlying surfactant dysfunction may predispose asthmatic subjects to further surfactant inhibition by proteins or aeroallergens in acute asthma episodes and contribute to airway closure in asthma. Consequently, administration of an appropriate therapeutic surfactant could provide clinical benefit in asthma.

Exogenous surfactant supplementation in infants with respiratory syncytial virus bronchiolitis

Infants with respiratory syncytial virus (RSV) bronchiolitis are deficient in surfactant, both in quantity and ability to reduce surface tension. New evidence suggests surfactant has a role in maintaining the patency of conducting airways, which has implications for RSV bronchiolitis. A randomized, controlled pilot study was undertaken to assess the effects of exogenous surfactant supplementation to RSV-positive infants on pulmonary mechanics, indices of gas exchange, and the phospholipid composition of bronchoalveolar lavage fluid (BALF). Nineteen ventilated infants (median corrected age 4 wk) received either two doses of surfactant (Survanta, 100 mg/kg) within 24 and 48 h of mechanical ventilation (n = 9), or air placebo (n = 10). Static lung compliance and resistance of infants in the placebo but not in the surfactant-treated group became progressively worse over the first 30 h following enrollment. Although no significant acute changes in gas exchange parameters were seen following surfactant, infants in the surfactant group showed a more rapid improvement in oxygenation and ventilation indices over the first 60 h of ventilation. Surfactant status was assessed from the concentration ratio in BALF of the disaturated phospholipid species dipalmitoylphosphatidylcholine to that of the monounsaturated species palmitoyloleoylphosphatidylcholine. This ratio correlated with both lung compliance (positively) and resistance (negatively), and over time increased in the treated group and declined in placebo infants. The data from this pilot study suggest that functional surfactant has a role in maintaining small airway patency as well as lung compliance in infants infected with RSV and an outcome study is now warranted.

National survey of internal medicine residency program directors regarding problem residents

CONTEXT

Internal medicine residency training is demanding and residents can experience a wide variety of professional and personal difficulties. A problem resident is defined by the American Board of Internal Medicine as "a trainee who demonstrates a significant enough problem that requires intervention by someone of authority." Data are sparse regarding identification and management of such residents.

OBJECTIVE

To gain more understanding of the prevalence, identification, management, and prevention of problem residents within US internal medicine residency programs.

DESIGN, SETTING, AND PARTICIPANTS

Mailed survey of all 404 internal medicine residency program directors in the United States in October 1999, of whom 298 (74%) responded.

MAIN OUTCOME MEASURES

Prevalence of problem residents; type of problems encountered; factors associated with identification and management of problem residents.

RESULTS

The mean point prevalence of problem residents during academic year 1998-1999 was 6.9% (SD, 5.7%; range, 0%-39%), and 94% of programs had problem residents. The most frequently reported difficulties of problem residents were insufficient medical knowledge (48%), poor clinical judgment (44%), and inefficient use of time (44%). Stressors and depression were the most frequently identified underlying problems (42% and 24%, respectively). The most frequent processes by which problem residents were discovered included direct observation (82%) and critical incidents (59%). Chief residents and attending physicians most frequently identified problem residents (84% and 76%, respectively); problem residents rarely identified themselves (2%). Many program directors believed that residents who are from an underrepresented minority, are international medical graduates, or are older than 35 years are at increased risk of being identified as a problem resident (P<.05). Program directors believed that frequent feedback sessions (65%) and an assigned mentor for structured supervision (53%) were the most helpful interventions.

CONCLUSION

Nearly all internal medicine residency programs in this sample had problem residents, whose presenting characteristics and underlying issues were diverse and complex. JAMA. 2000;284:1099-1104

Simultaneous optical and nuclear magnetic resonance spectroscopy for monitoring cardiac energetics in vivo

There are a number of applications in which it is useful to simultaneously collect data from what are traditionally separate instrumentation modalities. In particular, in vivo physiological investigations in which data from parallel experiments must be correlated would benefit from simultaneous data collection through 1) elimination of subject variability, 2) elimination of treatment variability, and 3) a reduction in the number of animal preparations required. Here we describe the simultaneous collection of fluo-3 optical fluorescence and 31P nuclear magnetic resonance (NMR) spectra to measure intracellular calcium levels and high-energy phosphate metabolism, respectively, in vivo. This work is part of ongoing research into the profound anoxia tolerance exhibited by the hearts of certain turtle species. An NMR compatible optical fluorescence spectrometer was constructed and tested. In the 31-cm bore of a 2 T superconducting magnet, NMR and optical spectra were collected every 10-15 min from the in situ, in vivo hearts of anesthetized turtle subjects prior to and during one to three hours of anoxia. It was found that while PCr stores became significantly depleted during anoxia, beta-adenosine triphosphate (ATP) levels remained within 20% of control values, and intracellular diastolic calcium levels did not vary by more than 10%. The ability to make simultaneous phosphorus and calcium measurements on a single subject is important to understanding the exact relationship between phosphorus energy state and maintenance of calcium homeostasis.

Capturing zebras: what to do with a reportable case

We had attempted to publish a report of an unusual manifestation of an uncommon disease discovered at autopsy. The case report was not accepted for publication because we had failed to order a highly specific test that would have unequivocally confirmed the diagnosis we entertained and subsequently wrote about. After much deliberation about this case and an extensive review of the literature, we now believe that there is a preferred approach to dealing with a reportable case. Because physicians seldom encounter cases that are reportable, we felt that sharing the important lessons we learned from our missed opportunity might prove helpful and encourage those who are considering preparing a case report for publication.

SMASH imaging with an eight element multiplexed RF coil array

SMASH (SiMultaneous Acquisition of Spatial Harmonics) is a technique which can be used to acquire multiple lines of k-space in parallel, by using spatial information from a radiofrequency coil array to perform some of the encoding normally produced by gradients. Using SMASH, imaging speed can be increased up to a maximum acceleration factor equal to the number of coil array elements. This work is a feasibility study which examines the use of SMASH with specialized coil array and data reception hardware to achieve previously unattainable accelerations. An eight element linear SMASH array was designed to operate in conjunction with a time domain multiplexing system to examine the effectiveness of SMASH imaging with as much as eightfold acceleration factors. Time domain multiplexing allowed the multiple independent array elements to be sampled through a standard single-channel receiver. SMASH-reconstructed images using this system were compared with reference images, and signal to noise ratio and reconstruction artifact power were measured as a function of acceleration factor. Results of the imaging experiments showed an almost constant SNR for SMASH acceleration factors of up to eight. Artifact power remained low within this range of acceleration factors. This study demonstrates that efficient SMASH imaging at high acceleration factors is feasible using appropriate hardware, and that time domain multiplexing is a convenient strategy to provide the multiple channels required for rapid imaging with large arrays.

When should learning about hospitalized patients end? Providing housestaff with post-discharge follow-up information

PURPOSE

As hospital stays grow shorter, many patients are discharged to follow up with their primary care physicians before their diagnoses and responses to treatment are clear. The authors studied the value and feasibility of providing housestaff with follow-up information about their former inpatients.

METHOD

Patients included in the study (1) had been admitted to the housestaff service during the study period (January to March 1997), (2) had received follow-up care from a primary care physician in the Johns Hopkins Bayview Physicians' Professional Association, and (3) had been hospitalized for at least three days. The primary care physician completed a single-page follow-up form four to six weeks after the patient's discharge from the hospital; that form was given to the house officers who had cared for that patient.

RESULTS

Responses to a preintervention questionnaire completed by 28 of 39 house officers (72%) showed that 92% felt it to be important or extremely important to get follow-up information about inpatients; 86% indicated that they rarely or never receive such information. During the study period, house officers were sent follow-up information for 65 of 76 eligible patients (85%). In their responses to a post-intervention questionnaire (response rate 73%), the house officers most valued learning about the accuracy of the discharge diagnosis, the results of additional diagnostic tests, and information about the patient's quality of life since discharge. Housestaff's satisfaction with the follow-up information received about inpatients improved (p = .001).

CONCLUSIONS

Providing follow-up information was a feasible intervention that was valued by housestaff.

Production of endothelin by cultured human endothelial cells following exposure to nicotine or caffeine

This study evaluated endothelin production by endothelial cells after exposure to nicotine or caffeine. Vasoconstrictive properties have been attributed to both nicotine and caffeine. The presence of endothelin, a potent vasoconstrictor itself, was determined using a radioimmunoassay. The optimal stimulatory doses for nicotine and caffeine were determined to be 1.0 micromol/L and 1.0 mmol/L, respectively. When endothelin production was evaluated over time after exposure to the optimal dose of each agent, it was determined that nicotine stimulated maximum endothelin production within 5 minutes. Caffeine failed to cause a distinct peak of endothelin production within 20 minutes. These results suggest that nicotine may have a possible acute and short-lived effect on the vasoconstrictive response associated with endothelin, while caffeine-induced endothelin release may require more long-term exposure.

Increasing use of Medicare services by veterans with acute myocardial infarction

OBJECTIVES

Some of the nation's 26 million veterans have two government-financed health care entitlements: Medicare and the Department of Veterans Affairs (VA). The aims of this investigation were to examine trends where Medicare-eligible VA users are initially hospitalized for acute myocardial infarction (AMI) and then to assess rates of cardiac procedure use and mortality for veterans initially admitted to each system of care.

METHODS

We used VA and HCFA national databases to identify VA users (age range, > or = 65 years) who were initially admitted to a VAMC or Medicare financed hospital (Medicare hospital) with a primary diagnosis of AMI between January 1, 1992, and December 31, 1995, (n = 47,598). We examined the use of cardiac procedures (cardiac catheterization [CC], coronary artery bypass surgery [CABG], and coronary angioplasty [CA] and mortality (30-day and 1-year) by the type of initial admitting hospital within each system of care.

RESULTS

Almost 70% of VA users hospitalized for AMI were initially admitted to Medicare hospitals versus VAMCs between 1992 (64%) and 1995 (72%). After adjusting for patient characteristics in logistic models, VA users initially hospitalized in Medicare hospitals were significantly more likely to undergo cardiac procedures than were VA users hospitalized in VAMCs. Differences in the odds of receiving a procedure were most significant when comparing Medicare hospitals with on-site cardiac technology to VA hospitals without on-site cardiac technology (CC: OR 4.34, 95% CI 3.98-4.73; CABG: OR 2.16, 95% CI 1.92-2.43; CA: OR 4.56, 95% CI 3.98-5.25). We found no significant differences in 30-day and 1-year adjusted mortality rates between VA users initially admitted to VAMCs or Medicare hospitals.

CONCLUSIONS

Medicare-eligible VA users are increasingly hospitalized in Medicare hospitals for AMI. VA users cared for in Medicare hospitals receive more cardiac procedures but have the same survival as VA users cared for in VAMCs. These findings have policy implications for access, quality, and costs in both systems of care.