bluuebunny/crossref_metadata_2025_split huggingface dataset:
Triple‐Doppler radar analysis of the heavy rain event observed in the Lago Maggiore region during MAP IOP 2b
Authors: Georgis Jean‐françois , Roux Frank , Chong Michel , Pradier Stephanie 
Published: March 2003

AbstractThis paper presents analyses of data collected with three ground‐based Doppler radars during the Mesoscale Alpine Programme (MAP) Intensive Observation Period (IOP) 2b from 1900 UTC 19 September until 1100 UTC 20 September 1999. During this period, the synoptic situation was characterized by the propagation of a deep upper‐tropospheric trough towards the Alps, as often observed when heavy precipitation occurs on the southern slopes of the Alpine massif. A frontal cloud system with embedded convective cells passed over northern Italy in association with the trough moving rapidly eastwards. Ahead of the advancing cold front, a strong south to south‐easterly low‐level flow impinged on the mountains near Lago Maggiore and produced copious amounts of rain (<200mm at several locations).An analysis of three‐dimensional radar‐derived wind and precipitation fields shows that the most intense precipitation occurred where and when the easterly component of the low‐ to mid‐level flow was the strongest with, however, a preferential location on the southern slopes of the Alps. This phenomenon can be explained by enhanced confluence between the main southerly flow and an intensifying easterly flow, and/or more favourable orientation of the moist inflow perpendicular to the mountain slopes. In addition, the propagation of convective cells from the Po Valley toward the Alps led to enhanced precipitation over the mountainous area.Taking advantage of the approximately two‐dimensional character of the event, the different terms of the water budget are calculated for a series of 25 successive vertical cross‐sections to analyse the transformation of atmospheric moisture into surface rainfall. Copyright © 2003 Royal Meteorological Society.
Structure and dynamics of an Alpine potential‐vorticity banner
Authors: Schär Christoph , Sprenger Michael , Lüthi Daniel , Jiang Qingfang , Smith Ronald B. , Benoit Robert 
Published: March 2003

AbstractA detailed analysis is undertaken of the primary Alpine shear zone that occurred on 1 October 1999 during the Mesoscale Alpine Programme. This shear zone emanates from the south‐western Alpine tip in north‐westerly flow conditions, develops in response to the Alpine‐scale flow splitting, and separates the northerly mistral wind to the south‐west of the Alps from the quasi‐stagnant air within the Alpine wake. The study is based on in situ flight‐level and dropsonde data from two research aircraft. The data are used for the construction of an objective analysis in a cross‐section perpendicular to the shear zone, and for diagnostic computations of the potential‐vorticity (PV) flux between vertically stacked flight legs. The observed flow structure is compared with simulation results of the Swiss Model and the non‐hydrostatic Canadian Mesoscale Compressible Community Model (MC2), operating at horizontal resolutions of 14 and 3 km, respectively.Immediately downstream of the topography, the observed shear zone has a surprisingly quasi‐steady structure that becomes evident provided a slow westward migration is accounted for. Further downstream, the shear zone shows increased signs of transience. Near the surface, it has an overall width of ∼150 km, but narrows to about 25 km near the top of the mistral inversion at a height of ∼2 km. Detailed analysis shows that the shear zone has a complex substructure consisting of at least three positive and three negative PV filaments. These shear lines are characterized by a pronounced vertical coherence in the mixed layer and throughout most of the inversion layer. One of the banners is also evident in low‐level tracer constituents. Diagnostic computations of the PV flux along the banners using the generalized Bernoulli theorem reveal that most of the associated PV flux is due to vertically oriented vorticity within the inversion layer. Within the shear zone, there is a spanwise circulation of appreciable strength. It consists of a deformation flow with the axes of deformation oriented perpendicular to the shear zone. This deformation flow in effect squeezes the PV banners and thereby makes them resilient with respect to dissipation and barotropic instabilities.Detailed intercomparison with numerical model results shows that models with a grid spacing below ∼15 km are able to capture the overall structure of the shear zone. The MC2 model in addition credibly replicates some of the finer‐scale sub‐structure of the shear zone, in particular at low levels. The high predictability and steadiness of the PV banners supports the idea that individual banners are generated by flow‐separation and/or gravity‐wave breaking events upstream. It is argued that the overall width of the shear zone is thus in effect determined by the geometry of the upstream topography and the dynamical processes that govern the downstream advection of the PV banners. Copyright © 2003 Royal Meteorological Society.
Runoff measurements and hydrological modelling for the estimation of rainfall volumes in an Alpine basin
Authors: Ranzi R. , Bacchi B. , Grossi G. 
Published: March 2003

AbstractStreamflow data and water levels in reservoirs have been collected at 30 recording sites in the Toce river basin and its surroundings, upstream of Lago Maggiore, one of the target areas of the Mesoscale Alpine Programme (MAP) experiment. These data have been used for two purposes: firstly, the verification of a hydrological model, forced by rain‐gauge data and the output of a mesoscale meteorological model, for flood simulation and forecasting; secondly, to solve an inverse problem—to estimate rainfall volumes from the runoff data in mountain areas where the influence of orography and the limits of actual monitoring systems prevent accurate measurement of precipitation. The methods are illustrated for 19–20 September 1999, MAP Intensive Observing Period 2b, an event with a 4‐year return period for the Toce river basin. Uncertainties in the estimates of the areal rainfall volumes based on rain‐gauge data and via the inverse solution are assessed. Copyright © 2003 Royal Meteorological Society.
Why do general practitioners request rheumatoid factor? A study of symptoms, requesting patterns and patient outcome
Authors: Sinclair David , Hull Richard G. 
Published: March 2003

Background: To investigate the reasons why general practitioners (GPs) request rheumatoid factor (RF) assays, we studied 200 consecutive requests for RF from general practice in 1995. Method: By means of an audit questionnaire, we studied 100 negative, 50 positive and 50 borderline RF results and compared these with the presenting symptoms that prompted the request, the GPs' understanding of the significance of the result, the referral intention and behaviour of the GP, and finally, the patient outcome after 5 years. Results: There was an 80% response rate. The presenting symptoms closely matched the American Rheumatism Association revised criteria for the classification of rheumatoid arthritis, indicating that the requests were made on valid clinical grounds, with polyarthralgia, morning stiffness and joint pain being the most common. Most GPs considered a negative or positive result to be meaningful, in that a positive RF meant that a referral was more likely than with a negative or borderline result, even in the presence of appropriate symptoms in all three groups. Seventeen to thirty per cent felt that the test excluded or confirmed RA. The result appeared to influence this decision to a greater extent than it should. A 5-year follow-up on these patients showed that 26/40 patients with positive RF were referred, and that 25 of them developed a rheumatic disease of some kind, with 17 patients eventually being diagnosed with RA. Only 17/80 patients with negative RF were referred, the remainder having no autoimmune problem evident after 5 years, 11 of them developing a rheumatic disease, and only three being diagnosed with RA. Conclusions: Although this is a locally based study, we believe the conclusions would be applicable to all laboratories and GPs undertaking these tests. RF requests are made on valid clinical grounds by GPs, but there may be an over-reliance on the results as regards referral behaviour. If patients were referred on clinical grounds, this would significantly lengthen consultants' waiting lists.
Immunoglobulins and immunoglobulin subclasses in the elderly
Authors: Lock R. J. , Unsworth D. J. 
Published: March 2003

Background: Published data imply that adult concentrations are achieved for all Ig isotypes and plateau by 15--18 years of age. Recent data, however, suggest that these results are not applicable in the elderly. There are no equivalent data for IgG subclasses. We present reference range data for an elderly UK patient population, for IgG, IgA, IgM and IgG subclasses. Methods: Serum immunoglobulins were reviewed on samples from 1146 patients > 60 years of age and 925 patients aged 18--60 years. Serum IgG subclasses were reviewed on samples from 498 patients >60 years and 484 patients aged 18--60 years. All Igs and subclasses were measured by nephelometry. Reference ranges were derived by probability plotting. Results: Serum median IgG and IgM concentrations are reduced in the elderly (IgG female P < 0·001, IgG male P < 0·03; IgM female P < 0·001, IgM male P < 0·001). Serum IgA concentrations are maintained. Indeed, men showed a slight increase in serum IgA with age ( P = 0·03). Few differences dependent on gender were seen. Median IgM was lower in men in the younger age groups (18--60 years P < 0·001; 61--70 years P = 0·017). IgG2 is reduced in elderly men ( P = 0·002) and IgG, reduced in elderly women ( P = 0·009). Conclusions: We advocate that centres offering these investigations provide local, method-dependent reference ranges, and suggest an approach as to how this might be achieved.
A survey of laboratory practice in the clinical authorization and reporting of results
Authors: Prinsloo P. J. J. , Gray T. A. 
Published: March 2003

Background: The aim of this survey was to determine the practice of authorization and reporting of results in clinical biochemistry laboratories in the UK. Method: Questionnaires were distributed to the heads of clinical biochemistry departments through the National Audit Committee of the Association of Clinical Biochemists. The standards surveyed were based on guidelines for the reporting of results produced by the Royal College of Pathologists and the relevant Clinical Pathology Accreditation standards. Results: Completed questionnaires were received from 137 laboratories. Workload ranged from 15 000 to 750 000 requests per annum (median 276 883). Most laboratories (98%) release results electronically to at least some wards in real-time. Areas where difficulties were identified included identifying requests that had posed specific questions and access to clinical information at the authorization stage, recording clinical advice given, and ensuring comments remained attached to printed reports or were on the same screen on computer reports. All but six laboratories had consultant advice available, including out of hours, but only 17% had an arrangement for clinical authorization to occur out of hours. Conclusion: Only 45 laboratories (33%) were able to achieve 100% compliance with the standards that currently exist, but many others showed evidence of good practice. The practical obstacles still to be overcome include limitations in the capabilities of laboratory computer systems, the lack of accessible electronic clinical records, the difficulties of covering work out of hours and insufficient appropriately trained staff.
Impact of European Society of Cardiology/American College of Cardiology guidelines on diagnostic classification of patients with suspected acute coronary syndromes
Authors: Collinson P. O. , Rao A. C. , Canepa-Anson R. , Joseph S. 
Published: March 2003

Background: Assessment of the relative diagnostic accuracy of investigation strategies for patients with suspected acute coronary syndromes (ACS). Methods: A prospective observational study followed two groups of patients over a 3-month period in a UK district general hospital. Group one: all admissions with suspected ACS ( n = 576); group two: non-cardiac in-patients who were suspected of developing ACS ( n = 87). Both were investigated by full clinical history, examination and serial electrocardiographs (ECGs). Conventional World Health Organization (WHO) criteria for myocardial damage were compared with diagnosis based on cardiac troponin T (cTnT). Clinical discharge diagnosis based on conventional WHO criteria was compared with the review diagnosis based on measurement of cTnT. Results: Diagnosis based on WHO criteria missed 58 patients (8·7%) admitted with suspected ACS who had high risk unstable angina. Thirty-three patients (5% of all admissions) who were diagnosed as non-Q wave acute myocardial infarction (AMI) were found to have normal troponin values and to have been incorrectly classified as AMI. Conclusions: Diagnostic strategies based on WHO criteria are inaccurate. The measurement of cTnT in all patients with suspected ACS would have increased the number of those with a diagnosis of AMI by 58 (8·7%), while avoiding inaccurate diagnosis in 33 (5%), therefore producing an absolute increase of 25/663 (3·8%) but a relative increase of 58/138 (42%). In patients with a primary diagnosis of suspected ACS, the overall increase in patients with a diagnosis of AMI will be 55 (9·5%), a relative increase of 55/118 (46·6%) but an absolute increase of 36/576 (6·3%).
The role of transferrin saturation as a screening test for hereditary haemochromatosis in an Irish population seeking medical care
Authors: O'Hara R. , Cavanagh N. , Cassidy M. , Cullina M. 
Published: March 2003

Background: Genetic studies have indicated a high prevalence of mutations for hereditary haemochromatosis (HH) in Irish populations. Given the high cost of genetic screening and the ethical implications thereof, we assessed the role of transferrin saturation (TS) as a primary screening test for HH in an Irish population seeking medical care. Methods: TS and ferritin were measured on 330 consecutive blood specimens received in the laboratory for routine screening. Patients with TS > 45% were genetically screened for the C282Y and H63D mutations. Results: Twenty-six patients had TS values > 45%. Of these, specimens were available for genetic screening on 20 patients. Three previously undiagnosed patients were found to be C282Y homozygotes and one a compound heterozygote (C282Y/H63D). The prevalence of C282Y homozygotes was 0·93%, which is similar to the reported prevalence found in Irish populations by genetic screening. Conclusion: Given the number of positive findings in this study, we conclude that, in the absence of a national programme, TS could be used as part of a health-screening panel in the Irish setting. Patients expressing iron overload would be detected before organ damage occurred, leading to less severe clinical disease and better patient prognosis.
Measurement of serum 'free' or 'easily dissociable' insulin-like growth factor-1
Authors: Roch M. , Williams J. , Clark P. M. 
Published: March 2003

Background: Serum insulin-like growth factor-1 (IGF-1) exists as ternary and binary complexes, and as the free hormone. An immunometric assay for 'free IGF-1' or 'easily dissociable IGF-1' has been described, although its use has not been widely assessed. Methods: The assay was assessed using the serum concentration/dilution test and by determining the relationship of the measured free hormone to the total hormone/binding protein ratio. Results: In six serum pools the measured free IGF-1 did not remain constant on concentration/dilution of the sample. However there was a significant correlation between the measured free IGF-1 and total IGF-1 ( P < 0·001) and between total IGF-1/IGF binding protein-3 ratio ( P < 0·001). Discussion: Although the assay failed the serum concentration/dilution test, there was still a significant relationship to the total hormone/binding protein ratio. It is possible that the serum dilution test is inappropriate to such a complex system or that the assay does not measure the free fraction. It is suggested that, though more cumbersome, it should be referred to as 'easily dissociable' IGF-1 as suggested by the manufacturers.
Field-testing and validation in a primary care setting of a point-of-care test for C-reactive protein
Authors: Seamark David A. , Backhouse Susan N. , Powell Roy 
Published: March 2003

Background: Use of point-of-care testing (POCT) in primary care has increased. There is a need for high-quality field evaluation of POCT before deployment can be considered. Method: A POCT system for C-reactive protein was evaluated in a routine general practice setting. The standard laboratory method was a dry slide method based in a routine hospital laboratory. Results: Scatterplots for both venous and capillary blood POCT system results versus the standard laboratory assay produced correlation coefficients of greater than 0·96. Bland-Altman plots indicated that 95% of venous and capillary POCT results fell within ±10 mg/L of the mean value with no clinically significant difference from laboratory results. Conclusions: The POCT system performed reliably in a routine general practice setting with satisfactory performance against an accepted laboratory method.
A survey of laboratory 'critical (alert) limits' in the UK
Authors: Tillman J. , Barth J. H. 
Published: March 2003

Introduction: Critical or alert limits are the values of laboratory measurements that are regarded as requiring urgent clinical action and should be communicated to a clinician urgently. Despite this, there has been little evaluation of these values in the UK. Methods: We have conducted a survey of hospital biochemistry laboratories in the UK. Results: Ninety-four laboratories responded to the questionnaire; the response rate was not recorded. Twenty-three laboratories had derived their action limits locally from a consensus with their clinicians, experience over many years, and the literature. Only two laboratories quoted literature to support their values. Seven laboratories did not submit actual critical values. There was considerable variance in the values defined as critical by the responding laboratories. Discussion: Each laboratory needs to evaluate its own list of acutely important critical values and aim for a small number of analytes that are always communicated to the doctor, so that clinical needs are met without raising the risk of information overload.
Comparison of simple acid-ethanol precipitation with gel exclusion chromatography for measuring leptin binding in serum of normal subjects and cancer patients
Authors: Jamieson Nigel B. , McMillan Donald C. , Brown Duncan J. F. , Wallace A. Michael 
Published: March 2003

Background: In humans, leptin circulates in a free form and is also bound to macromolecules. The aim of the present study was to compare a rapid acid-ethanol precipitation (AEP) method of measuring bound leptin with the more laborious gel exclusion chromatography (GEC) reference procedure. Serum samples collected from healthy subjects and cancer patients were used in this comparison. Methods: AEP and GEC methods for measuring leptin binding in serum (from 14 healthy volunteers and 14 patients with advanced non-small cell lung cancer) were adapted from previously published procedures. Results: Intra- and inter-assay precision of the AEP method were 6% ( n = 10) and 8% ( n = 10), respectively. Bland-Altman analysis of results obtained from the AEP and GEC methods indicated no significant difference in healthy controls. However, significantly higher results were obtained by the AEP method in the cancer patients. Conclusions: Evaluation of the AEP method revealed that on examination of normal subjects the method was less precise than had previously been reported. Moreover, the method gave differing results in the cancer patients when compared with the GEC method. This study indicates that careful evaluation of any new method for measuring leptin binding requires comparison with a GEC method using the sample matrix of interest.
Effect of a protease inhibitor on in vitro stability of intact parathyroid hormone
Authors: Anderson N. R. , Nicholas J. , Holland M. R. , Gama R. 
Published: March 2003

Background: We investigated whether increased protease activity explains the increased in vitro degradation of intact parathyroid hormone (iPTH) observed in serum when compared to EDTA plasma. Methods: Pre-dialysis blood samples for iPTH were taken from 11 patients with chronic renal failure and collected into plain glass tubes, tubes containing 200 KIU/mL aprotinin (a protease inhibitor) and EDTA tubes. All sample aliquots were separated at 20 min, 1 h, 2 h, 4 h, 8 h and 24 h post collection. Results: Over 24 h, iPTH concentrations remained unchanged in EDTA tubes. iPTH concentrations were significantly lower in both plain tubes ( P < 0·01) and aprotinin tubes ( P < 0·001) at 24 h when compared to the baseline sample (20 min). At 24 h, iPTH concentrations in EDTA tubes were higher than in plain tubes ( P < 0·001) and aprotinin tubes ( P < 0·01). The addition of aprotinin to plain tubes significantly reduced the degradation of iPTH ( P < 0·05) at 24 h. Conclusion: Aprotinin significantly reduces the in vitro degradation of iPTH in plain tubes at 24 h from 24·7% to 9·6%. We suggest that increased protease activity contributes to the decline in serum iPTH over time. As this is observed in serum and not plasma it suggests that the increased protease activity may be due to the clotting process.
Stability of parathyroid hormone ex vivo in haemodialysis patients
Authors: Teal T. K. , Reed M. , Stevens P. E. , Lamb E. J. 
Published: March 2003

Background: The stability of parathyroid hormone (PTH) in blood ex vivo is a significant practical problem for laboratories and clinicians. Several studies have suggested that PTH is more stable in blood collected into a potassium edetate (EDTA) preservative. Methods: To confirm that this was applicable to renal dialysis patients using our assay (Nichols chemiluminescence), we examined PTH stability in 13 patients with end-stage renal failure using three different blood collection tubes. Results: PTH remained stable in EDTA plasma for up to 48 h at room temperature. PTH was significantly reduced in serum collected into plain tubes after 2 h, and after 4 h in serum collected into serum separator tubes, at room temperature. Conclusion: In the assessment of renal osteodystrophy, the use of EDTA plasma can confer significant benefit, especially in busy laboratories where rapid frozen separation of blood may be hard to achieve.
How frequent are accessory sinus ostia?
Authors: Jog M. , McGarry G. W. 
Published: March 2003

The frequency of accessory sinus ostia (ASO) has been estimated at between four and 50 per cent in the findings of studies designed for other purposes or from uncontrolled observations. The literature revealed no study specifically designed to determine the prevalence of ASO. We have carried out a prospective cohort study to measure the prevalence of ASO.The prevalence of ASO was determined in rhinology clinic patients and general ENT clinic controls. Overall ASO occurred in four per cent. Seven per cent of rhinology patients and two per cent of controls had ASO. Of the rhinology patients with rhinitis or sinusitis, eight per cent exhibited ASO. The overall prevalence in this study is lower than most quoted figures in the literature. There was increased prevalence of ASO in patients with rhinitis or sinusitis compared to controls. (p<0.05)This study should be regarded as a pilot study and further investigations of the relationship between ASO and nasal disease is merited.