Biomedical subjects
P Barnes
Publications and source records attributed to P Barnes.
Redox behavior of Fe-Mo-O catalysts studied by ultrarapid in situ diffraction.
Explore the source record for details and available documents.
17-Beta estradiol administration attenuates deficits in sustained and divided attention in young ovariectomized rats and aged acyclic female rats.
Recent evidence suggests that estrogen may interact with the basal forebrain cholinergic system to influence learning. The authors examined whether the loss of estrogen following ovariectomy (Experiment 1) or the disruption to the estrogen cycle during aging (Experiment 2) impaired performance of the 5-choice serial reaction time task (5-CSRT)--a sustained and divided attention task sensitive to cholinergic challenges in rats. In Experiment 1, posttraining ovariectomy in young rats did not disrupt baseline performance but did impair performance when attention was challenged by variation in the intertrial interval (ITI) or in the intermittent presentation of a novel distracting auditory stimulus. Administration of 17-beta estradiol rescued these impairments. Through the use of a within-subjects design, Experiment 2 revealed that 17-beta estradiol did not influence the baseline performance of 21-month-old female rats trained on the 5-CSRT task from a young age but did improve performance when attention was challenged by varying the ITI or by presenting a distracting auditory cue. The results indicate that 17-beta estradiol administration can improve specific components of attention in young ovariectomized rats and gonadally intact aged female rats.
The new materials processing beamline at the SRS Daresbury, MPW6.2.
A new beamline (MPW6.2) has been designed and built for the study of materials during processing where three synchrotron techniques, SAXS, WAXS and XAS, are available simultaneously. It has been demonstrated that Rietveld refinable data can be collected from silicon SRM 640b over a 60 degrees range in a time scale of 1 s. The data have been refined to a chi(2) of 2.4, the peaks fitting best to a Pearson VII function or with fundamental parameters. The peak halfwidths have been found to be approximately constant at 0.06 degrees over a 120 degrees angular range indicating that the instrumental resolution function has matched its design specification. A quantitative comparison of data sets collected on the same isotactic polypropylene system on MPW6.2 and DUBBLE at the ESRF shows a 17% improvement in angular resolution and a 1.8 improvement in peak-to-background ratio with the RAPID2 system; the ESRF data vary more smoothly across detector channels. The time-dependent wide-angle XRD was tested by comparing a hydration reaction of gypsum-bassanite-anhydrite with energy-dispersive data collected on the same system on the same time scale. Three sample data sets from the reaction were selected for analysis and gave an average chi(2) of 3.8. The Rietveld-refined lattice parameters are a good match with published values and the corresponding errors show a mean value of 3.3 x 10(-4). The data have also been analysed by the Pawley decomposition phase-modelling technique demonstrating the ability of the station to quickly and accurately identify new phases. The combined SAXS/WAXS capability of the station was tested with the crystallization and spinodal decomposition of a very dilute polymer system. Our measurements show that the crystallization of a high-density co-polymer (E76B38) as low as 0.5% by weight can be observed in solution in hexane. The WAXS and SAXS data sets were collected on the same time scale. The SAXS detector was calibrated using a collagen sample that gave 30 orders of diffraction in 1 s of data collection. The combined XRD and XAS measurement capability of the station was tested by observing the collapse and re-crystallization of zinc-exchanged zeolite A (zeolite Zn/Na-A). Previous studies of this material on station 9.3 at the SRS were compared with those from the new station. A time improvement of 38 was observed with better quality counting statistics. The improved angular resolution from the WAXS detector enabled new peaks to be identified.
Practice parameter: neuroimaging of the neonate: report of the Quality Standards Subcommittee of the American Academy of Neurology and the Practice Committee of the Child Neurology Society.
OBJECTIVE: The authors reviewed available evidence on neonatal neuroimaging strategies for evaluating both very low birth weight preterm infants and encephalopathic term neonates. IMAGING FOR THE PRETERM NEONATE: Routine screening cranial ultrasonography (US) should be performed on all infants of <30 weeks' gestation once between 7 and 14 days of age and should be optimally repeated between 36 and 40 weeks' postmenstrual age. This strategy detects lesions such as intraventricular hemorrhage, which influences clinical care, and those such as periventricular leukomalacia and low-pressure ventriculomegaly, which provide information about long-term neurodevelopmental outcome. There is insufficient evidence for routine MRI of all very low birth weight preterm infants with abnormal results of cranial US. IMAGING FOR THE TERM INFANT: Noncontrast CT should be performed to detect hemorrhagic lesions in the encephalopathic term infant with a history of birth trauma, low hematocrit, or coagulopathy. If CT findings are inconclusive, MRI should be performed between days 2 and 8 to assess the location and extent of injury. The pattern of injury identified with conventional MRI may provide diagnostic and prognostic information for term infants with evidence of encephalopathy. In particular, basal ganglia and thalamic lesions detected by conventional MRI are associated with poor neurodevelopmental outcome. Diffusion-weighted imaging may allow earlier detection of these cerebral injuries. RECOMMENDATIONS: US plays an established role in the management of preterm neonates of <30 weeks' gestation. US also provides valuable prognostic information when the infant reaches 40 weeks' postmenstrual age. For encephalopathic term infants, early CT should be used to exclude hemorrhage; MRI should be performed later in the first postnatal week to establish the pattern of injury and predict neurologic outcome.
Psychostimulants for hypersomnia (excessive daytime sleepiness) in myotonic dystrophy.
BACKGROUND: Excessive daytime sleepiness is a common symptom of myotonic dystrophy. Psychostimulants are drugs increasingly used to treat hypersomnia in myotonic dystrophy. OBJECTIVES: To search systematically for, and combine all evidence from, randomised trials relating to the effects of psychostimulants in myotonic dystrophy patients with hypersomnia. SEARCH STRATEGY: We searched the Cochrane Neuromuscular Disease Trial Register (searched May 2001) for randomised trials concerning psychostimulants in myotonic dystrophy, we searched of the bibliographies of identified papers and we contacted the authors of the papers. SELECTION CRITERIA: We considered all randomised or quasi randomised trials that have evaluated any type of psychostimulants (versus a placebo or no treatment) in children or adults with proven myotonic dystrophy and hypersomnia. DATA COLLECTION AND ANALYSIS: Potentially relevant papers were scrutinised by two reviewers and the selection of eligible studies was agreed by them and a third reviewer. Data were extracted by one reviewer and checked by a second reviewer. MAIN RESULTS: Primary outcome We found no trial that assessed the effect of a psychostimulant on the results of the maintenance of wakefulness tests. Secondary outcomes Only one eligible trial was found. In this crossover double blind study of 10 patients with myotonic dystrophy, the efficacy of selegiline was evaluated against a placebo on the multiple sleep latency test. There was no difference between the selegiline and placebo periods in mean improvement in the multiple sleep latency test scale. REVIEWER'S CONCLUSIONS: There is no evidence to support the use of a psychostimulant to treat hypersomnia in myotonic dystrophy. Randomised trials are needed to evaluate the efficacy and safety of psychostimulants.
Recreational injury and its relation to socioeconomic status among school aged children in the US.
OBJECTIVES: This study described epidemiologic patterns of recreational injuries among school aged children in the US and assessed the relation of these patterns to socioeconomic status. METHODS: Combined data from the 1997-98 National Health Interview Surveys for 38 458 children aged 6-17 years regarding non-fatal recreational injury episodes that received medical attention, reported by a household adult, were analysed. Logistic regression analysis was used to assess the association between recreational injury and socioeconomic status while controlling for confounding factors. RESULTS: The annualized rate of recreational injury was 91.2 episodes per 1,000 children, with an increased risk associated with a higher family income status or being non-Hispanic white. For children from not poor families, most injury episodes occurred in sport facilities, whereas for children from poor and near poor families, most occurred outside the home. CONCLUSION: Recreational injury is a significant health problem for school aged children in the US. Non-Hispanic white children and children from affluent families are at increased risk of recreational injury.
Regulating safety in an unsafe world (risk reduction for and with communities).
Safety regulators and the public they serve often have contrasting views on risk perception and the veracity of institutional estimates of risk and harm. Conflict and distrust between these groups is often a result of a lack of public involvement in decision making on safety related matters. Such concerns also emerge from differences in professional training, authority and experience between the groups. Fire services internationally, carryout fire safety assessments on behalf of communities. This assessment role is unusual in that unlike conventional approaches to regulatory safety assessment, fire fighters are direct end-users of their own regulatory assessment and closer to the people they protect. This paper discusses how fire services are beginning to seek closer links with communities by defining clear regulatory frameworks for conventional safety assessments and conceptual frameworks that allow a redefinition of their role towards establishing partnerships with communities to promote sustained safety.
Subversion of integrins by enteropathogenic Yersinia.
Enteropathogenic Yersinia are gram-negative bacterial species that translocate from the lumen of the intestine and are able to grow within deep tissue sites. During the earliest stages of disease, the organism is able to bind integrin receptors that are presented on the apical surface of M cells in the intestine, which allows its internalization and subsequent translocation into regional lymph nodes. The primary integrin substrate is the outer-membrane protein invasin, which binds with extraordinarily high affinity to at least five different integrins that have the (beta)(1) chain. Bacterial uptake into host cells is modulated by the affinity of receptor-substrate interaction, receptor concentration and the ability of the substrate to aggregate target receptors.
Evaluation and management of children younger than two years old with apparently minor head trauma: proposed guidelines.
OBJECTIVE: In children <2 years old, minor head trauma (HT) is a common injury that can result in skull fracture and intracranial injury (ICI). These injuries can be difficult to detect in this age group; therefore, many authors recommend a low threshold for radiographic imaging. Currently, no clear guidelines exist regarding the evaluation and management of head-injured infants. We sought to develop guidelines for management based on data and expert opinion that would enable clinicians to identify children with complications of HT and reduce unnecessary imaging procedures. METHODS. EVIDENCE: References addressing pediatric HT were generated from a computerized database (Medline). The articles were reviewed and evidence tables were compiled. EXPERT PANEL: The multidisciplinary panel was comprised of nine experts in pediatric HT. CONSENSUS PROCESS: A modified Delphi technique was used to develop the guidelines. Before the one meeting, panel members reviewed the evidence and formulated answers to specific clinical questions regarding HT in young children. At the meeting, guidelines were formulated based on data and expert consensus. RESULTS: A management strategy was developed that categorizes children into 4 subgroups, based on risk of ICI. Children in the high-risk group should undergo a computed tomography (CT) scan. Those in the intermediate risk group with symptoms of possible ICI should either undergo CT scan or observation. Those in the intermediate risk group with some risk for skull fracture or ICI should undergo CT and/or skull radiographs or observation. Those in the low-risk group require no radiographic imaging. CONCLUSIONS: We have developed a guideline for the evaluation of children <2 years old with minor HT. The effect of these guidelines on clinical outcomes and resource utilization should be evaluated.
Time- and space-resolved dynamic studies on ceramic and cementitious materials.
A review is given of the results and lessons arising from a sustained in situ diffraction study of the structure and performance of functional ceramic/cementitious materials in which synchrotron-based energy-dispersive diffraction has been the central under-pinning technique. Five particular points of discussion emerge: the demands on time resolution; the use of penetrating radiation for the in situ mode; the need for complementary techniques; re-analysing of data; spatially resolved diffraction: a new tomography. These aspects are discussed in turn using illustrative examples taken from the fields of cement hydration, clay intercalation, cation-exchanged zeolites, and particulate/fluid invasion into building and archaeological objects.
Border patrols and secret passageways across the intestinal epithelium.
Explore the source record for details and available documents.
The use of a task-based exposure assessment model (T-BEAM) for assessment of metal fume exposures during welding and thermal cutting.
Elevated disease rates have been documented among construction workers for cancer, pneumonoconiosis, asbestosis, and silicosis. However, methodologies for exposure assessment in construction are not well described in the U.S. literature. Working through a cooperative agreement with the National Institute for Occupational Safety and Health (NIOSH), the Center to Protect Workers' Rights--a research arm of the Building and Construction Trades Department, AFL-CIO--has developed and used a "Task-Based Exposure Assessment Model (T-BEAM)" for construction. The characteristic elements of T-BEAM are: (1) an emphasis on the identification, implementation, and evaluation of engineering and work practice controls; and (2) use of experienced, specially trained construction workers (construction safety and health specialists) in the exposure assessment process. A task-based approach was used because tasks, or specialized skills, form the single greatest thread of continuity in the dynamic environment of construction. Workers in the construction industry come from several crafts and are typically employed by a large number of contractors throughout their career. Project types (e.g., residential or industrial rehabilitation) are also highly variable and present unique health risks. Finally, because construction involves building, renovating, or dismantling physical surroundings, the work site is constantly changing. Between 1995 and 1996, T-BEAM was applied to the collection of approximately 200 personal exposure measurements associated with "hot work tasks"--welding and thermal cutting. Data were collected with the assistance of specially trained, journeyman ironworkers, pipe fitters, and boilermakers on nine construction sites located throughout the United States. Portable local exhaust ventilation was provided to participating contractors with the intent of measuring its impact on exposure. Results indicate that data collected in a standardized, systematic fashion from multiple work sites can be used to characterize exposures among sampled trades. Comparison of results to American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs) demonstrate a significant health hazard among sampled trades posed by welding and thermal cutting fume, manganese, nickel, and chromium VI. Direct estimates of the probability of exceeding the ACGIH TLV for respirable particulate suggests that boilermakers (100%) and ironworkers (71%) are at greatest risk. Other task variables evaluated with respect to exposure include task, whether work was performed indoors or outdoors, intermittency of work, and use of ventilation. Use of local or mechanical ventilation reduced mean exposures to fumes significantly.
Clinical evaluation of a new, point-of-care hemocytometer.
OBJECTIVE: This study was designed to compare results obtained with a new point-of-care hemocytometer with those of two established (point-of-care and laboratory-based) instruments. DESIGN: To compare CBC values between established laboratory-based and point-of-care instruments, measurements were performed on routinely obtained blood specimens for CBC analysis in our institutional laboratory (phase I) and on specimens from cardiac surgical patients before initiation of cardiopulmonary bypass and after discontinuation of cardiopulmonary bypass in phase II. SETTING: Surgical and hospitalized patients at a tertiary care center. PATIENTS: Measurements were obtained by using blood specimens obtained from 141 hospitalized patients from different services (phase I) or from a consecutive series of 204 patients undergoing cardiac operations (phase II). MEASUREMENTS AND MAIN RESULTS: Hemoglobin (HGB), platelet count (PLT), red blood cell count, and white blood cell count (WBC) were measured with two on-site and one laboratory-based instruments. Hematocrit (HCT) was calculated by using measured variables. Linear regression demonstrated good correlations between Ichor and T540 HGB (r2 = .95), HCT (r2 = .95), PLT (r2 = .94), and WBC (r2 = .95) results (n = 408); similarly, good correlations were observed with Coulter STKS HGB (r2 = .92), HCT (r2 = .91), and PLT (r2 = .94) results (n = 141). The relationship between Ichor and Coulter STKS WBC (r2 = .27) was poor; however, when two Ichor-derived outlier values (>50) were excluded, the relationship was very good (r2 = .99). Bias analysis (mean +/- SD) demonstrated similar results between Ichor and T540 HGB (0.003+/-0.5), HCT (-0.21+/-1.5), WBC (0.79+/-1.3), and PLT values (-9.2+/-16.6) as well as STKS HGB (-0.08+/-0.7), HCT (-0.69+/-2.3), WBC (-0.62+/-5.8), and PLT values (-10.2+/-21.4). CONCLUSIONS: The Ichor hemocytometer provides accurate hematologic results that can facilitate rapid quantitative assessment of CBC variables and thus may be clinically useful, especially in critically ill patients.
Lung neutrophil burden correlates with increased pro-inflammatory cytokines and decreased lung function in individuals with alpha(1)-antitrypsin deficiency
Explore the source record for details and available documents.
Tuberous sclerosis in the fetus: second-trimester diagnosis of subependymal tubers with ultrafast MR imaging.
Explore the source record for details and available documents.
The nurse clinician in surgical services.
Nurses are able to undertake some of the tasks previously performed by junior doctors. The nurse clinician role allows nurses to apply their nursing skills within a medically oriented framework. Managerial support and ongoing training are needed to ensure the continued success of this role.
Effect of chronic excess of tumour necrosis factor-alpha on contractile proteins in rat skeletal muscle.
The effect of chronic tumour necrosis factor-alpha (TNF-alpha) treatment on the synthesis of specific myofibrillar proteins such as heavy chain myosin, light chain myosin and G-actin in rat diaphragm were evaluated. Muscles (diaphragm) from control and experimental groups (TNF-alpha i.v. at 50 microg/kg body wt for 5 days) were incubated in the presence of 35S-methionine for 2 h. Myofibrillar protein extracts were prepared and protein was electrophoresed on sodium dodecyl sulphate-polyacrylamide gels. Heavy chain myosin, light chain myosin and G-actin were identified by Western blot analysis using specific monoclonal antibodies. Polyacrylamide gel electrophoresis (PAGE) followed by Western blot analysis revealed two types of heavy chain myosin (206 and 212 kD), all four types of light chain myosin (15, 16.5, 18 and 20 kD) and a single type of G-actin (42 kD). Chronic TNF-alpha treatment produced a significant decline in the synthesis of all types of myofibrillar proteins, namely heavy chain myosin, light chain myosin and G-actin. TNF-alpha impaired peptide-chain initiation in diaphragm muscle which was reversed by the branched-chain amino acids (BCAA) therapy of TNF-alpha treated rats. These findings indicate a significant role for TNF-alpha in the translational regulation of protein synthesis in skeletal muscle.