Lower Specificity (lower + specificity)

Distribution by Scientific Domains

Selected Abstracts

Viable Myocardium: How Much Is Enough?

A Comparison of Viability by Comparative Imaging Techniques to Assess the Quantity, Functionality of Ischemic Myocardium
Left ventricular systolic dysfunction is mainly a result of coronary artery disease (CAD). Decrease in myocardial contractility results as a response to a chronic hypoperfusion state that produces a change in cardiac myocyte metabolism, resulting in a perfusion-contraction mismatch in which function is sacrificed for survival. If revascularization is performed in a timely fashion, metabolism can be restored leading to recovery of function. Through the use of noninvasive imaging modalities, assessing myocardial viability can be easily performed and will aid in selecting those patients who will benefit from revascularization. Viable myocardium can be identified by nuclear modalities that have a high sensitivity but a lower specificity, such as thallium-201 single photon emission computed tomography and positron emission tomography (PET); or by the use of dobutamine stress echocardiogram (DSE), which has a decreased sensitivity but a better specificity. A modality that is increasingly being used with an overall good sensitivity and specificity is contrast-enhanced magnetic resonance imaging. The purpose of this review is to explore the amount of myocardial viability that is relevant to pursue revascularization, since as myocardial function improves there is a decrease in morbidity and mortality from heart failure and arrhythmias. [source]

Role of prey,host plant associations on Harmonia axyridis and Episyrphus balteatus reproduction and predatory efficiency

Ammar Alhmedi
Abstract In order to predict possible locations of Harmonia axyridis Pallas (Coleoptera: Coccinellidae) and Episyrphus balteatus DeGeer (Diptera: Syrphidae) in the field, we studied their oviposition and prey preferences in relation to several host plant,prey associations under laboratory conditions. Oviposition preference of H. axyridis and E. balteatus females was determined for three aphid (Homoptera: Aphididae),host plant associations: Microlophium carnosum Buckton on stinging nettle [Urtica dioica L. (Urticaceae)], Acyrthosiphon pisum Harris on green pea [Pisum sativum L. (Fabaceae)], and Sitobion avenae F. on wheat [Triticum aestivum L. (Poaceae)]. Prey preference of H. axyridis and E. balteatus larvae was determined with the aphids M. carnosum, A. pisum, and S. avenae. Harmonia axyridis females showed a strong oviposition preference for the stinging nettle,M. carnosum association. The preferred association for ovipostion by E. balteatus was pea-hosting A. pisum, on which fecundity was also highest. Feeding behaviour was less restricted in H. axyridis, in which the preferred preys were M. carnosum and S. avenae. A lower specificity of predation was observed in E. balteatus larvae with respect to A. pisum. These laboratory experiments may help us to understand the spatial distribution of H. axyridis and E. balteatus in the field. [source]

Motor foundations of higher cognition: similarities and differences in processing regular and violated perceptual sequences of different specificity

Andreja Bubic
Abstract Processing perceptual sequences relies on the motor system, which is able to simulate the dynamics of the environment by developing internal representations of external events and using them to predict the incoming stimuli. Although it has previously been demonstrated that such models may incorporate predictions based on exact stimulus properties and single stimulus dimensions, it is not known whether they can also support abstract predictions pertaining to the level of stimulus categories. This issue was investigated within the present event-related functional magnetic resonance imaging study, which compared the processing of perceptual sequences of different specificity, namely those in which the sequential structure was based on the order of presentation of individual stimuli (token), and those in which such structure was defined by stimulus categories (type). The results obtained indicate a comparable engagement of the basic premotor,parietal network in processing both specific and categorical perceptual sequences. However, type sequences additionally elicited activations within the lateral prefrontal, occipital and posterior temporal regions that supported categorization in this task context. Introducing sequential deviants into token sequences activated parietotemporal and ventrolateral frontal cortices, whereas a less pronounced overall response, dominated by lateral prefrontal activation, was elicited by violations introduced into type sequences. Overall, the findings obtained suggest that, although forward models in perception may be able to incorporate expectations of lower specificity when compared to the motor domain, such processing is crucially dependent on additional contributions from lateral prefrontal as well as inferior occipital and temporal cortices that support categorization occurring in such a dynamic context. [source]

Prospective Validation of a Modified Thrombolysis In Myocardial Infarction Risk Score in Emergency Department Patients With Chest Pain and Possible Acute Coronary Syndrome

Erik P. Hess MD
Abstract Objectives:, This study attempted to prospectively validate a modified Thrombolysis In Myocardial Infarction (TIMI) risk score that classifies patients with either ST-segment deviation or cardiac troponin elevation as high risk. The objectives were to determine the ability of the modified score to risk-stratify emergency department (ED) patients with chest pain and to identify patients safe for early discharge. Methods:, This was a prospective cohort study in an urban academic ED over a 9-month period. Patients over 24 years of age with a primary complaint of chest pain were enrolled. On-duty physicians completed standardized data collection forms prior to diagnostic testing. Cardiac troponin T-values of >99th percentile (,0.01 ng/mL) were considered elevated. The primary outcome was acute myocardial infarction (AMI), revascularization, or death within 30 days. The overall diagnostic accuracy of the risk scores was compared by generating receiver operating characteristic (ROC) curves and comparing the area under the curve. The performance of the risk scores at potential decision thresholds was assessed by calculating the sensitivity and specificity at each potential cut-point. Results:, The study enrolled 1,017 patients with the following characteristics: mean (±SD) age 59.3 (±13.8) years, 60.6% male, 17.9% with a history of diabetes, and 22.4% with a history of myocardial infarction. A total of 117 (11.5%) experienced a cardiac event within 30 days (6.6% AMI, 8.9% revascularization, 0.2% death of cardiac or unknown cause). The modified TIMI risk score outperformed the original with regard to overall diagnostic accuracy (area under the ROC curve = 0.83 vs. 0.79; p = 0.030; absolute difference 0.037; 95% confidence interval [CI] = 0.004 to 0.071). The specificity of the modified score was lower at all cut-points of >0. Sensitivity and specificity at potential decision thresholds were: >0 = sensitivity 96.6%, specificity 23.7%; >1 = sensitivity 91.5%, specificity 54.2%; and >2 = sensitivity 80.3%, specificity 73.4%. The lowest cut-point (TIMI/modified TIMI >0) was the only cut-point to predict cardiac events with sufficient sensitivity to consider early discharge. The sensitivity and specificity of the modified and original TIMI risk scores at this cut-point were identical. Conclusions:, The modified TIMI risk score outperformed the original with regard to overall diagnostic accuracy. However, it had lower specificity at all cut-points of >0, suggesting suboptimal risk stratification in high-risk patients. It also lacked sufficient sensitivity and specificity to safely guide patient disposition. Both scores are insufficiently sensitive and specific to recommend as the sole means of determining disposition in ED chest pain patients. ACADEMIC EMERGENCY MEDICINE,2010; 17:368,375 © 2010 by the Society for Academic Emergency Medicine [source]

Diagnostic accuracy of D-dimer test for exclusion of venous thromboembolism: a systematic review

Summary.,Background: The reported diagnostic accuracy of the D-dimer test for exclusion of deep vein thrombosis (DVT) and pulmonary embolism (PE) varies. It is unknown to what extent this is due to differences in study design or patient groups, or to genuine differences between D-dimer assays. Methods: Studies evaluating the diagnostic accuracy of the D-dimer test in the diagnosis of venous thromboembolism were systematically searched for in the MEDLINE and EMBASE databases up to March 2005. Reference lists of all included studies and of reviews related to the topic of the present meta-analysis were manually searched for other additional potentially eligible studies. Two reviewers independently extracted study characteristics using standardized forms. Results: In total, 217 D-dimer test evaluations for DVT and 111 for PE were analyzed. Several study design characteristics were associated with systematic differences in diagnostic accuracy. After adjustment for these features, the sensitivities of the D-dimer enzyme-linked immunofluorescence assay (ELFA) (DVT 96%; PE 97%), microplate enzyme-linked immunosorbent assay (ELISA) (DVT 94%; PE 95%), and latex quantitative assay (DVT 93%; PE 95%) were superior to those of the whole-blood D-dimer assay (DVT 83%; PE 87%), latex semiquantitative assay (DVT 85%; PE 88%) and latex qualitative assay (DVT 69%; PE 75%). The latex qualitative and whole-blood D-dimer assays had the highest specificities (DVT 99%, 71%; PE 99%, 69%). Conclusions: Compared to other D-dimer assays, the ELFA, microplate ELISA and latex quantitative assays have higher sensitivity but lower specificity, resulting in a more confident exclusion of the disease at the expense of more additional imaging testing. These conclusions are based on the most up-to-date and extensive systematic review of the topic area, including 184 articles, with 328 D-dimer test evaluations. [source]

A direct comparison of pulsed dye, alexandrite, KTP and Nd:YAG lasers and IPL in patients with previously treated capillary malformations,

David J. McGill MRCS(Ed)
Abstract Introduction Several studies have reported laser treatment of Capillary Malformations (CMs) using systems other than pulsed dye lasers (PDL). Few, however, have compared different systems in the same patients. This study aimed to directly compare CM fading using five different systems. Methods Eighteen previously PDL-treated patients were test-patched using the alexandrite, KTP, and Nd:YAG lasers and intense pulsed light (IPL) with additional PDL patches as a control. Pre- and post-treatment videomicroscopy, and colour measurements using Munsell colour charts were carried out. Results Four patients failed to respond to any test patches. The alexandrite laser test patches had the largest mean improvement in Munsell colour following treatment (P,=,0.023) and resulted in CM fading in 10 patients, although 4 patients developed hyperpigmentation, and 1 patient scarring, following treatment. In addition, the alexandrite laser caused a significant decrease in mean post-treatment capillary diameter (P,=,0.007), which was not mirrored by the other systems. The KTP and Nd:YAG lasers were least effective, with fading seen in two patients for both systems, whilst IPL patches resulted in CM fading in six patients. In addition, five patients had further CM fading using double-passed PDL treatment. Mean pre-treatment capillary diameter measurements were predictive of those patients likely to respond to laser treatment. Conclusions Alexandrite laser treatment was the most effective, but resulted in hyperpigmentation and scarring in four patients, probably due to its deeper penetration and lower specificity for oxyhaemoglobin causing non-specific dermal damage. Double passing of the PDL can result in further CM fading even in previously treated patients. Videomicroscopy measurements of capillary diameter before treatment may be predictive of the likelihood for patient's to respond to laser treatment. Lesers Surg. Med. 40:390,398, 2008. © 2008 Wiley-Liss, Inc. [source]

Potential role of the cellular allergen stimulation test (CAST) in diagnosis of allergic bronchopulmonary aspergillosis (ABPA) in cystic fibrosis

Stephanie Ringer MD
Abstract Allergic bronchopulmonary aspergillosis (ABPA) is a severe complication in cystic fibrosis (CF), which is difficult to identify because of overlapping unspecific diagnostic features with common CF-manifestations. The cellular allergen stimulation test (CAST) is used in diagnosis of allergic and pseudoallergic reactions. This assay is based on the determination of sulfidoleukotrienes, which are produced by allergen-stimulated basophils in vitro. The potential role of CAST in diagnosis of ABPA was evaluated in this study. The CAST assay was applied in 27 CF-patients including eight subjects with positive clinical and serological signs of ABPA. Additional to the Nelson-criteria for diagnosis of ABPA specific IgE against recombinant Aspergillus antigens (rAsp f 1, 2, 3, 4, and 6) were assessed. The CAST results were positive in all ABPA-patients and in five controls without any sign of ABPA except positive specific IgE against Aspergillus fumigatus (sensitivity of 100%, specificity of 74%). Specific IgE against rAsp f 4 and/or f 6 were positive in six of the eight ABPA-patients, but not in the controls. Positive CAST results, total serum IgE,>,500 U/ml and positive IgE antibodies against rAsp f 4 and/or f 6 were only found in ABPA-patients (specificity of 100%). The CAST assay on its own includes high sensitivity with lower specificity. For the discrimination of ABPA from sensitization to Aspergillus, the CAST, the highly elevated total serum IgE and rAsp in combination are potential auxiliary diagnostic parameters. Pediatr Pulmonol. 2007; 42:314,318. © 2007 Wiley-Liss, Inc. [source]

Protein probabilities in shotgun proteomics: Evaluating different estimation methods using a semi-random sampling model

Xiaofang Xue
Abstract The calculation of protein probabilities is one of the most intractable problems in large-scale proteomic research. Current available estimating methods, for example, ProteinProphet, PROT_PROBE, Poisson model and two-peptide hits, employ different models trying to resolve this problem. Until now, no efficient method is used for comparative evaluation of the above methods in large-scale datasets. In order to evaluate these various methods, we developed a semi-random sampling model to simulate large-scale proteomic data. In this model, the identified peptides were sampled from the designed proteins and their cross-correlation scores were simulated according to the results from reverse database searching. The simulated result of 18 control proteins was consistent with the experimental one, demonstrating the efficiency of our model. According to the simulated results of human liver sample, ProteinProphet returned slightly higher probabilities and lower specificity than real cases. PROT_PROBE was a more efficient method with higher specificity. Predicted results from a Poisson model roughly coincide with real datasets, and the method of two-peptide hits seems solid but imprecise. However, the probabilities of identified proteins are strongly correlated with several experimental factors including spectra number, database size and protein abundance distribution. [source]

Endothelial Gene Expression in Kidney Transplants with Alloantibody Indicates Antibody-Mediated Damage Despite Lack of C4d Staining

Banu Sis
Anti-HLA alloantibody is a risk factor for graft loss, but does not indicate which kidneys are experiencing antibody-mediated rejection (ABMR). C4d staining in biopsies is specific for ABMR but insensitive. We hypothesized that altered expression of endothelial genes due to alloantibody acting on the microcirculation would be sensitive indicator of ABMR. We identified 119 endothelial-associated transcripts (ENDATs) from literature, and studied their expression by microarrays in 173 renal allograft biopsies for cause. Mean ENDAT expression was increased in all rejection but was higher in ABMR than in T-cell-mediated rejection and correlated with histopathologic lesions of ABMR, and alloantibody. Many individual ENDATs were increased in ABMR and predicted graft loss. Kidneys with high ENDATs and antibody showed increased lesions of ABMR and worse prognosis in comparison to controls. Only 40% of kidneys with high ENDAT expression and chronic ABMR or graft loss were diagnosed by C4d positivity. High ENDAT expression with antibody predicts graft loss with higher sensitivity (77% vs. 31%) and slightly lower specificity (71% vs. 94%) than C4d. The results were validated in independent set of 82 kidneys. High renal endothelial transcript expression in patients with alloantibody is indicator of active antibody-mediated allograft damage and poor graft outcome. [source]

A comparison of urinary nuclear matrix protein-22 and bladder tumour antigen tests with voided urinary cytology in detecting and following bladder cancer:the prognostic value of false-positive results

V. Poulakis
Objectives To evaluate the diagnostic and prognostic value of the nuclear matrix protein-22 (NMP22) and bladder tumour antigen (BTAstat) tests compared with voided urinary cytology (VUC) in detecting and following bladder cancer, assessing particularly the prognostic value of false-positive test results in patients followed up for bladder cancer. Patients and methods From 739 patients suspected of having bladder cancer, voided urine samples for the NMP22 and BTAstat tests, and for VUC and urine analysis, were collected before cystoscopy. All patients underwent transurethral resection of bladder lesions or mapping, and were followed for a mean (range) of 27.3 (3,65) months. Results In the 406 patients with bladder cancer, the overall sensitivity was 85% for NMP22, 70% for BTAstat and 62% for VUC. For histological grades 1,3 the sensitivity in detecting transitional cell carcinoma was 82%, 89% and 94% for NMP22, 53%, 76% and 90% for BTAstat, and 38%, 68% and 90% for VUC, respectively. Although the sensitivity in detecting invasive carcinoma was > 85% for all the tests, NMP22 and BTAstat were statistically more sensitive than VUC for superficial tumours. The optimal threshold value for NMP22, calculated using the receiver operating characteristics curve, was 8.25 U/mL. The specificity was 68% for NMP22, 67% for BTAstat, and 96% for VUC. The specificity of VUC remained > 87% and was independent of benign histological findings. In contrast, in patients with no apparent genitourinary disease on histology, NMP22 and BTAstat had significantly higher specificity (94% and 92%, respectively; P = 0.003) than in the group with chronic cystitis (52% for both tests). Forty patients having no bladder cancer at biopsy had a recurrence after a mean (range) follow-up of 7.7 (3,15) months; all had a previous history of bladder cancer. According to subsequent recurrence, the prognostic positive and negative predictive values were 18% and 91% for NMP22, 13% and 88% for BTAstat, and 79% and 91% for VUC. Both false-positive VUC and NMP22 tests predicted recurrence (log-rank test, P < 0.001 and P = 0.004, respectively), but the BTAstat test produced no similar correlation (P = 0.778). Conclusion The NMP22 and BTAstat tests are better than VUC for detecting superficial and low-grade bladder cancer but they have significantly lower specificity. After excluding diseases with the potential to interfere in these tests the overall specificity of both tests is increased considerably. False-positive results from NMP22 and VUC but not from BTAstat in patients followed up for bladder cancer correlate with future recurrences. [source]

Diagnostic accuracy of Heidelberg Retina Tomograph III classifications in a Turkish primary open-angle glaucoma population

Banu Bozkurt
Abstract. Purpose:, This study aimed to evaluate the diagnostic accuracy of Moorfields regression analysis (MRA) and the glaucoma probability score (GPS) in primary open-angle glaucoma (POAG) and to measure the level of agreement between the two algorithms in classifying eyes as normal or abnormal in a Turkish population. Methods:, We prospectively selected 184 healthy subjects and 158 subjects with POAG, who underwent an ophthalmological examination, visual field analysis and imaging with the Heidelberg Retina Tomograph II, using HRT III software, Version 3.0. The diagnostic accuracies of the two classifications were measured when the borderline was taken as either normal (highest specificity criteria) or abnormal (highest sensitivity criteria). The agreement between them was calculated using the unweighted kappa (,) coefficient. Results:, Optic nerve head topographic parameters showed statistically significant differences between the control and POAG groups (p < 0.001). The parameters with the highest area under the receiver operating characteristic curves were global GPS (0.86), cup : disc area (0.85), rim : disc area (0.85) and vertical cup : disc (0.85). According to the highest specificity criteria, MRA had a sensitivity of 67.7% and a specificity of 95.1%, whereas the GPS had a sensitivity of 70.9% and a specificity of 88.0%. According to the highest sensitivity criteria, MRA had a sensitivity of 81.0% and a specificity of 75.0%, whereas the GPS had a sensitivity of 89.2% and a specificity of 57.6%. A moderate agreement of 68% (233 eyes) with a , coefficient of 0.51 was found between MRA and the GPS. Conclusions:, The GPS automated classification showed similar sensitivity to MRA, but considerably lower specificity, when applied in a Turkish population. [source]

Assessment of subjective scales for selection of patients for nasal septal surgery

J.M. Boyce
Objective:, To investigate the use of subjective measures to assist the surgeon in patient selection for septal surgery. Study design:, Prospective, observational. Approved by local ethics committee. Setting:, ENT outpatient department, University Hospital of Wales. Participants:, Forty-six participants on the waiting list for septal surgery for nasal obstruction. Main outcome measure:, Measurement of nasal partitioning of airflow by rhinospirometer (GM Instruments, Scotland), subjective scales, and investigator's assessment of septal deviation. Results:, The subjective scores, and investigator's assessment of septal deviation, were compared with the rhinospirometer objective measurements for correlation, sensitivity and specificity. The rhinospirometry results showed that 20% of the patients on the waiting list had objective measures of partitioning of nasal airflow within a normal range for healthy subjects. The ordinal scale proved to be more useful than the visual analogue scale for patient selection. The subjective scores of airflow partitioning from the double ordinal scale correlated well with the rhinospirometry measurements (r = 0.8). The ordinal scale also had a sensitivity of 81% and a specificity of 60%. The investigator's subjective assessment of septal deviation had a high sensitivity at around 100% but had a lower specificity (30%). Conclusions:, The use of a subjective ordinal scale to measure partitioning of airflow greatly increased the specificity of patient selection and it is proposed that this scale may be useful to the surgeon when assessing patients for septal surgery. [source]