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PubMed2001

The negative predictive value of spiral computed tomography for the diagnosis of pulmonary embolism in patients with nondiagnostic ventilation-perfusion scans.

BACKGROUND: There is no noninvasive method to rule out pulmonary embolism when the clinical suspicion for pulmonary embolism is high. We did a prospective observational study to determine the negative predictive value of spiral computed tomography (CT) in this situation. METHODS: We performed spiral CT scans of the thorax in consecutive patients with high clinical suspicion of pulmonary embolism with intermediate or low probability ventilation-perfusion scans. Patients with negative or indeterminate spiral CT results had conventional angiography at the discretion of the attending physician. Only patients with positive spiral CT results or positive conventional angiograms were treated. All patients were observed for 6 months for evidence of venous thromboembolic disease. Clinical outcome without treatment or the results of conventional angiography were used as reference standards. False-negative results were defined as a negative spiral CT with a positive conventional angiogram or any diagnosis of venous thromboembolism within 6 months. RESULTS: Among the 103 patients who were studied, spiral CT scans were positive in 22 patients, indeterminate in 10 patients, and negative in 71 patients. Twenty-seven (26%) patients had pulmonary embolism by clinical outcome, including 3 of the 71 patients with negative spiral CT scans and 2 of the 10 patients with indeterminate scans. A negative spiral CT result had a likelihood ratio of 0.12 (95% confidence interval [CI]: 0.04 to 0.35) with a negative predictive value of 96% (95% CI: 88% to 99%). Using conventional angiography only as the reference standard, a negative spiral CT result had a likelihood ratio of 0.08 (95% CI: 0.02 to 0.31) and a negative predictive value of 93% (95% CI: 77% to 98%). CONCLUSIONS: Spiral CT has a high negative predictive value for pulmonary embolism and may replace conventional angiography in the workup of pulmonary embolism. Patients with indeterminate spiral CT results should be considered for conventional angiography.

Adult↗

PubMed1997

Evaluating measurement variability in clinical investigations: the case of ultrasonic estimation of urinary bladder volume.

OBJECTIVE: To evaluate the quality of studies seeking to establish measurement properties (reliability and validity) of ultrasonic estimation of urinary bladder volume. DESIGN: Online searching of the MEDLINE database between 1966 and 1995, and scanning of bibliography of known studies on ultrasonic bladder volume estimation. Study selection and study quality assessment were performed independently by two reviewers. Each article was evaluated for suitability of the reference standard, adequacy of reported blinding of the observers and appropriateness of the statistical index of concordance. The last two of these guidelines were applied to reliability studies (evaluating the relation among observed ultrasonic estimations), and all three guidelines were applied to validity studies (evaluating the relation of ultrasonic estimation with a definitive measurement). POPULATION: One hundred and twenty-five participants enrolled in the five reliability studies and 769 participants in the 27 validity studies selected for appraisal of their quality. MAIN OUTCOME MEASURE: Rate of study compliance with preset criteria for high quality. RESULTS: None of the studies complied with all of the criteria for high methodologic quality. In the five reliability studies, investigators did not report adequate blinding of observers in three (60%) and an appropriate index of reliability was not used in any. Among the 27 validity studies, there was a lack of a suitable reference standard in 6 (22%), an inadequate blinding in 25 (93%), and an inappropriate index of validity in all (100%). CONCLUSION: Based on our guidelines for quality assessment, a large proportion of studies on measurement properties was found to have inadequate methods, raising concern about the credibility of the reliability and validity estimates reported. These deficiencies highlight the lack of rigour employed in the design, conduct and analysis of reliability and validity studies, which has the potential for leading to patient mismanagement due to biases in the assessment of measurement variability in clinical investigations.

Humans↗

PubMed2024

Evaluating culture-free targeted next-generation sequencing for diagnosing drug-resistant tuberculosis: a multicentre clinical study of two end-to-end commercial workflows.

BACKGROUND: Drug-resistant tuberculosis remains a major obstacle in ending the global tuberculosis epidemic. Deployment of molecular tools for comprehensive drug resistance profiling is imperative for successful detection and characterisation of tuberculosis drug resistance. We aimed to assess the diagnostic accuracy of a new class of molecular diagnostics for drug-resistant tuberculosis. METHODS: We conducted a prospective, cross-sectional, multicentre clinical evaluation of the performance of two targeted next-generation sequencing (tNGS) assays for drug-resistant tuberculosis at reference laboratories in three countries (Georgia, India, and South Africa) to assess diagnostic accuracy and index test failure rates. Eligible participants were aged 18 years or older, with molecularly confirmed pulmonary tuberculosis, and at risk for rifampicin-resistant tuberculosis. Sensitivity and specificity for both tNGS index tests (GenoScreen Deeplex Myc-TB and Oxford Nanopore Technologies [ONT] Tuberculosis Drug Resistance Test) were calculated for rifampicin, isoniazid, fluoroquinolones (moxifloxacin, levofloxacin), second line-injectables (amikacin, kanamycin, capreomycin), pyrazinamide, bedaquiline, linezolid, clofazimine, ethambutol, and streptomycin against a composite reference standard of phenotypic drug susceptibility testing and whole-genome sequencing. FINDINGS: Between April 1, 2021, and June 30, 2022, 832 individuals were invited to participate in the study, of whom 720 were included in the final analysis (212, 376, and 132 participants in Georgia, India, and South Africa, respectively). Of 720 clinical sediment samples evaluated, 658 (91%) and 684 (95%) produced complete or partial results on the GenoScreen and ONT tNGS workflows, respectively, with 593 (96%) and 603 (98%) of 616 smear-positive samples producing tNGS sequence data. Both workflows had sensitivities and specificities of more than 95% for rifampicin and isoniazid, and high accuracy for fluoroquinolones (sensitivity approximately ≥94%) and second line-injectables (sensitivity 80%) compared with the composite reference standard. Importantly, these assays also detected mutations associated with resistance to critical new and repurposed drugs (bedaquiline, linezolid) not currently detectable by any other WHO-recommended rapid diagnostics on the market. We note that the current format of assays have low sensitivity (≤50%) for linezolid and more work on mutations associated with drug resistance is needed. INTERPRETATION: This multicentre evaluation demonstrates that culture-free tNGS can provide accurate sequencing results for detection and characterisation of drug resistance from Mycobacterium tuberculosis clinical sediment samples for timely, comprehensive profiling of drug-resistant tuberculosis. FUNDING: Unitaid.

Humans↗

PubMed2005

Accuracy of fetal echocardiography in the routine detection of congenital heart disease among unselected and low risk populations: a systematic review.

OBJECTIVE: To determine among unselected and low risk populations the accuracy with which fetal echocardiography during the second trimester detects congenital heart disease. DESIGN: A systematic review of studies that assess the accuracy of fetal echocardiography. SETTING: District General Hospital and Tertiary referral centres. POPULATION: Women during the second trimester attending for ultrasound assessment. METHODS: General bibliographic databases (e.g. MEDLINE, EMBASE) and specialist computerised databases (e.g. Cochrane Library, National Research Register), grey literature, manual searching of reference lists of primary and review articles and personal contact with experts were used to identify studies. Studies were included if fetal echocardiography among unselected or low risk pregnant women was compared against a postnatal reference standard. Data were extracted on quality, study design and characteristics, and accuracy data to construct 2 x 2 tables. Data were synthesised qualitatively, and sensitivity and specificity with 95% confidence intervals were calculated. MAIN OUTCOME MEASURE: Sensitivity and specificity. RESULTS: Five primary studies met the inclusion criteria and comprised 60,901 subjects. One study assessed the accuracy of fetal echocardiography among an unselected population and four studies among low risk populations. All eligible studies found that fetal echocardiography helped to correctly diagnose normal fetus among unselected and low risk populations. Correct diagnosis of babies for congenital heart defects was higher among the unselected population (85%) than among the low risk populations (range from 35% to 86%); however, the potential for ascertainment bias and the choice of reference standard limits the validity of this finding. The variation in sensitivity across studies was not explainable by clinical factors such as scanning regime, operator skill and equipment. CONCLUSIONS: The evidence from this review about the accuracy of fetal echocardiography does not lend support to its routine use among unselected and low risk populations during the second trimester to detect congenital heart disease.

Echocardiography↗

PubMed1996

Methodological issues in determining rates of childhood immunization in office practice. A study from pediatric research in office settings (PROS).

OBJECTIVE: To compare 3 methods for measuring pediatric office immunization rates. DESIGN: Retrospective and prospective cross-sectional surveys. PATIENTS: Children 2 and 3 years old from 15 pediatric practices in 11 states. METHODS: Immunization rates were determined for each practice using 3 methods. The Consecutive method used data from the practice's medical records of patients seen consecutively in the office; the Chart method used data from randomly selected practice medical records; and the Active method (reference standard) used a combination of medical record data with a telephone interview to collect additional immunization data and current patient status, using data only on current patients. Analyses were based on a mean of 57, 62, and 51 (Consecutive, Chart, and Active method, respectively) patients per practice. Patients were considered fully immunized if they had received 4 doses of DTP/DT vaccine, 3 doses of OPV/IPV, and 1 dose of MMR vaccine by their second birthday Comparisons were made using the paired t test. RESULTS: The mean immunization rate by method was Consecutive, 81.5% (range, 51%-97%); Chart, 71.6% (range, 42%-94%); and Active, 79.6% (range, 53%-96%). Within a given practice, the differences between methods varied considerably (0 to 28 percentage points). The mean difference from the reference standard Active method was 8 percentage points (P < .001) for the Chart method and -1.9 percentage points (P = .36) for the Consecutive method. The largest difference was between the Consecutive and Chart methods (mean difference, 9.9 percentage points; P = .003). Practitioners uniformly found the Consecutive method easiest to implement. CONCLUSIONS: Practice-specific immunization rates are one of the few objective measures of the quality of preventive pediatric care. Pediatric practices monitoring their immunization rates should consider using the Consecutive method, a simple, acceptable, and valid measure of practice immunization rate.

Child↗

PubMed2006

Detection of primary angle closure using anterior segment optical coherence tomography in Asian eyes.

OBJECTIVE: To evaluate noncontact anterior segment optical coherence technology (AS-OCT) as a qualitative method of imaging the anterior chamber angle and to determine its ability to detect primary angle closure when compared with gonioscopy in Asian subjects. DESIGN: Prospective observational case series. PARTICIPANTS: Two hundred three subjects were recruited from glaucoma clinics in Singapore with diagnoses of primary angle closure, primary open-angle glaucoma, ocular hypertension, or cataract. Both eyes (if eligible) of each patient were included in the study. Exclusion criteria were pseudophakia or previous glaucoma surgery. METHODS: Images of the nasal, temporal, and inferior angles were obtained with AS-OCT in dark and then light conditions. Gonioscopic angle width was graded using the Spaeth classification for each quadrant in low lighting conditions. MAIN OUTCOME MEASURES: Angle closure was defined by AS-OCT as contact between the peripheral iris and angle wall anterior to the scleral spur and by gonioscopy as a Spaeth grade of 0 degree (posterior trabecular meshwork not visible). Comparison of the 2 methods in detecting angle closure was done by eye and by individual. Sensitivities and specificities of AS-OCT were calculated using gonioscopy as the reference standard. RESULTS: Complete data were available for 342 eyes of 200 patients. Of the patients, 70.9% had a clinical diagnosis of treated or untreated primary angle closure. Angle closure in > or =1 quadrants was detected by AS-OCT in 142 (71%) patients (228 [66.7%] eyes) and by gonioscopy in 99 (49.5%) patients (152 [44.4%] eyes). The inferior angle was closed more frequently than the nasal or temporal quadrants using both AS-OCT and gonioscopy. When performed under dark conditions, AS-OCT identified 98% of those subjects found to have angle closure on gonioscopy (95% confidence interval [CI], 92.2-99.6) and led to the characterization of 44.6% of those found to have open angles on gonioscopy to have angle closure as well. With gonioscopy as the reference standard, specificity of AS-OCT in the dark was 55.4% (95% CI, 45.2-65.2) for detecting individuals with angle closure. CONCLUSION: Anterior segment OCT is a rapid noncontact method of imaging angle structures. It is highly sensitive in detecting angle closure when compared with gonioscopy. More persons are found to have closed angles with AS-OCT than with gonioscopy.

Adult↗

PubMed1992

Measurement of oral malodor: current methods and future prospects.

Measurement of oral malodor is complicated by a variety of parameters including complexity of gaseous molecular species, sampling difficulties, temporal variations, choice of suitable subject populations, and lack of agreement on reference standards. Since oral malodor is a perceived olfactory stimulus, direct sampling and assessment by human judges may be the most logical measurement approach. However, as with other psychophysical assessments, human malodor measurement by the human nose may vary widely among and between judges, and consequently cannot be confidently reproduced in other laboratories. Such shortcomings have led several investigators to propose quantitative approaches based on measurement of volatile sulfide compounds which are associated with oral malodor. Highly sensitive and discriminatory measurements of volatile sulfides can be made using gas chromatography although for rapid sampling of larger subject populations, portable sulfide monitors may be more appropriate. Future research in this field should consider: 1) improved and simplified instrumentation for more rapid through-put and reliability; 2) development and definition of reference standards for oral malodor assessment; 3) formulation of clinical studies with appropriately sized, well-defined patient populations; and 4) further development of within mouth, site-specific measurements.

Halitosis↗

PubMed2005

Orthopedic hardware complications diagnosed with multi-detector row CT.

PURPOSE: To retrospectively evaluate multi-detector row computed tomography (CT) for the depiction of orthopedic hardware complications in the spine and appendicular skeleton. MATERIALS AND METHODS: This HIPAA-compliant study had institutional review board approval; patient informed consent was not required. Results of 114 multi-detector row CT studies performed because of possible hardware complications in 109 patients (57 men, 52 women; mean age, 44 years; age range, 12-82 years) were available for analysis. The CT studies were retrospectively reviewed and compared with clinical or surgical outcomes, which were used as the reference standard. In another experiment, detection of hardware complications on radiographs and multi-detector row CT images was compared between two readers for selected cases (18 positive and 26 negative) by using receiver operating characteristic (ROC) methods. RESULTS: For 91 (80%) of 114 multi-detector row CT studies, the complication status could be determined on the basis of clinical or surgical outcomes. Twenty-three multi-detector row CT studies were confirmed to be positive (revealing 10 cases of nonunion, five cases of hardware malplacement, three cases of hardware loosening, three perihardware fractures, and two chronic infections), and 57 were confirmed to be negative. There were three false-positive and eight false-negative multi-detector row CT studies. With clinical or surgical outcomes as the reference standard, the sensitivity, specificity, and positive and negative predictive values of multi-detector row CT were 74% (23 of 31 studies), 95% (57 of 60 studies), 88% (23 of 26 studies), and 88% (57 of 65 studies), respectively. Results of ROC analysis indicated that detection of hardware complications was much lower with radiography than with multi-detector row CT (area under ROC curve, 0.84 vs 1.00; F = 4.69, df = 1, 43; P < .05). CONCLUSION: Multi-detector row CT is an effective tool for depicting orthopedic hardware complications.

Adolescent↗

PubMed2026

Performance of AI-Based Screening Tools for Obstructive Sleep Apnea Across Apnea-Hypopnea Index Thresholds: Systematic Review and Meta-Analysis.

BACKGROUND: Obstructive sleep apnea (OSA) is highly prevalent but remains substantially underdiagnosed. Polysomnography (PSG) is the reference standard, but its cost and limited availability constrain large-scale case identification. AI-based screening tools may support risk stratification and referral prioritization, but their diagnostic accuracy across apnea-hypopnea index (AHI) thresholds remains uncertain. OBJECTIVE: This review aimed to systematically evaluate the diagnostic accuracy of AI-based OSA screening tools at AHI thresholds of ≥5, ≥15, and ≥30 events/hour, with emphasis on models using non-PSG-derived inputs. METHODS: PubMed, Embase, Scopus, and Web of Science were searched for studies published from January 1, 2016, to May 3, 2026. Eligible studies included adults evaluated for suspected OSA or recruited from population-based cohorts, assessed AI-based models intended or interpretable for OSA screening, risk prediction, or screening-oriented severity classification, used PSG as the reference standard, and reported sufficient data to construct or reconstruct 2×2 contingency tables. Diagnostic accuracy was synthesized separately by AHI threshold and input source using bivariate random-effects models, with 95% CIs and prediction intervals (PIs). Risk of bias and certainty of evidence were assessed using QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies 2) and GRADE (Grading of Recommendations Assessment, Development, and Evaluation), respectively. RESULTS: A total of 60 studies were included, of which 47 contributed data to the meta-analysis. At AHI thresholds of ≥5, ≥15, and ≥30 events/hour, pooled sensitivities were 0.94 (95% CI 0.92-0.96; 95% PI 0.71-0.99), 0.87 (95% CI 0.84-0.89; 95% PI 0.66-0.96), and 0.83 (95% CI 0.79-0.87; 95% PI 0.61-0.94), respectively; the corresponding specificities were 0.77 (95% CI 0.69-0.84; 95% PI 0.30-0.96), 0.81 (95% CI 0.75-0.85; 95% PI 0.39-0.96), and 0.91 (95% CI 0.87-0.94; 95% PI 0.55-0.99), respectively. The corresponding areas under the summary receiver operating characteristic curves were 0.943, 0.907, and 0.920. For non-PSG-derived tools, sensitivities were 0.92, 0.85, and 0.81, and specificities were 0.70, 0.74, and 0.85 at the 3 thresholds, respectively. For PSG-derived models, sensitivities were 0.96, 0.90, and 0.85, and specificities were 0.82, 0.88, and 0.96, respectively. Exploratory subgroup analyses suggested performance variation across selected study and model characteristics, including region, algorithmic framework, data source, and validation method. CONCLUSIONS: AI-based tools showed generally favorable screening performance for OSA across clinically relevant AHI thresholds, although wide PIs suggest variable performance across future comparable populations and settings. By synthesizing diagnostic accuracy across 3 AHI thresholds and distinguishing non-PSG-derived from PSG-derived models, this review extends previous broad or modality-specific reviews and offers a clinically interpretable, pathway-specific basis for linking model performance to intended use. The findings may clarify potential roles for non-PSG-derived tools in front-end screening and referral prioritization and for PSG-derived models in reduced-channel assessment and sleep-laboratory workflow support. Given substantial heterogeneity, limited external validation, and low or very low certainty of evidence, prospective validation is needed before routine implementation.

Humans↗

PubMed2006

DOVER and QUVER-new marker combinations to detect and monitor at-risk drinking.

BACKGROUND: At-risk drinking is a common medical problem. "Objective" laboratory tests are widely used, especially in situations where it might be favorable for the patient to dissimulate the existing alcohol problem. In this study, we report a new approach to combine the biological markers % carbohydrate-deficient transferrin (%CDT) and gamma-glutamyltransferase (gammaGT) to increase diagnostic properties to identify patients with at-risk drinking behavior. METHODS: Fifty-eight general practitioners (GPs) participated in the study at 2 study sites in South-West Germany. Patients filled in a questionnaire that included the Alcohol Use Disorders Identification Test (AUDIT) and gave a blood sample. The GP recorded his assessment about the presence of an alcohol-related disorder in the patient. Screening results of 1 test center were used as a calculation sample. The results at the other site were used to cross-validate the study outcomes. The markers were combined by 2 methods. The first approach used the AUDIT (QUestionnaire VERified; QUVER), and the second was performed using the clinical judgment of the treating GP (DOctor VERified; DOVER). The formulas were calculated using linear and logistic regression models, respectively. RESULTS: A total of 2,940 patients participated in the study, of whom 2,496 completed data sets that could be used for further analysis. In the receiver-operating characteristics (ROC) curves with the reference standard of an AUDIT> or =8, the area under the curve (AUC) of 78.8% for DOVER and 80.6% (QUVER) are in a higher range than the values for gamma-%CDT (75.4%) or gamma-GT (66.3%) and %CDT (74.3%) and suggest a clear superiority of the proposed marker combinations. Regarding the combinations DOVER and QUVER, the cross-validation results were almost identical, with 78.4/78.8% and 80.6/79.5%, respectively. CONCLUSION: Our study is to date the largest practice-based trial that examines the value of the markers CDT and gamma-GT and their combinations for the screening of at-risk drinking in general practice under routine conditions. Our ROC analysis clearly demonstrated that the combination of the markers gamma-GT and %CDT under routine conditions with a behaviorally oriented reference standard leads to an improvement of diagnostic performance, more so than the use of single markers.

Adult↗

PubMed2000

Accuracy of the Papanicolaou test in screening for and follow-up of cervical cytologic abnormalities: a systematic review.

PURPOSE: To evaluate the accuracy of conventional and new methods of Papanicolaou (Pap) testing when used to detect cervical cancer and its precursors. DATA SOURCES: Systematic search of English-language literature through October 1999 using MEDLINE, EMBASE, other computerized databases, and hand searching. STUDY SELECTION: All studies that compared Pap testing (conventional methods, computer screening or rescreening, or monolayer cytology) with a concurrent reference standard (histologic examination, colposcopy, or cytology). DATA EXTRACTION: Two reviewers independently reviewed selection criteria and completed 2 x 2 tables for each study. DATA SYNTHESIS: 94 studies of the conventional Pap test and three studies of monolayer cytology met inclusion criteria. No studies of computerized screening were included. Data were organized by cytologic and histologic thresholds used to define disease. For conventional Pap tests, estimates of sensitivity and specificity varied greatly in individual studies. Methodologic quality and frequency of histologic abnormalities also varied greatly between studies. In the 12 studies with the least biased estimates, sensitivity ranged from 30% to 87% and specificity ranged from 86% to 100%. CONCLUSIONS: Insufficient high-quality data exist to estimate test operating characteristics of new cytologic methods for cervical screening. Future studies of these technologies should apply adequate reference standards. Most studies of the conventional Pap test are severely biased: The best estimates suggest that it is only moderately accurate and does not achieve concurrently high sensitivity and specificity. Cost-effectiveness models of cervical cancer screening should use more conservative estimates of Pap test sensitivity.

Cervix Uteri↗

PubMed2006

Diagnosis of invasive aspergillosis using a galactomannan assay: a meta-analysis.

BACKGROUND: A double-sandwich enzyme-linked immunosorbent galactomannan assay has been approved for surveillance for invasive aspergillosis in immunocompromised patients. We undertook a meta-analysis to assess the accuracy of a galactomannan assay for diagnosing invasive aspergillosis. METHODS: Studies of the galactomannan assay that used the European Organization for Research and Treatment of Cancer or similar criteria as a reference standard and provided data to calculate sensitivity and specificity were included. Pooled sensitivity and specificity and summary measures of accuracy, Q* (the upper left-most point on the summary receiver-operating characteristic curve), mean D (a log odds ratio), and Youden index were calculated. Subgroup analyses were performed to explore heterogeneity. RESULTS: Twenty-seven studies from 1966 to 28 February 2005 were included. Overall, the galactomannan assay had a sensitivity of 0.71 (95% confidence interval [CI], 0.68-0.74) and specificity of 0.89 (95% CI, 0.88-0.90) for proven cases of invasive aspergillosis. The Youden index, mean D, and Q* were 0.54 (95% CI, 0.41-0.65), 2.74 (95% CI, 21.12-3.36), and 0.80 (95% CI, 0.74-0.86), respectively, indicating moderate accuracy. Subgroup analyses showed that the performance of the test differed by patient population and type of reference standard used. Significant heterogeneity was present. CONCLUSIONS: The galactomannan assay has moderate accuracy for diagnosis of invasive aspergillosis in immunocompromised patients. The test is more useful in patients who have hematological malignancy or who have undergone hematopoietic cell transplantation than in solid-organ transplant recipients. Further studies with attention to the impact of antifungal therapy, rigorous assessment of false-positive test results, and assessment of the utility of the test under nonsurveillance conditions are needed.

Aspergillosis↗

PubMed2002

A reactive analytical approach for the estimation of olefinic content in gasoline-range hydrocarbons by gas chromatography.

The estimation of olefinic content in conversion processes such as the etherification of olefins in fluid catalytic cracking (FCC) gasoline is essentially required. Gas chromatography (GC) is the well-established method for the quantitative analysis of olefins in etherification processes. The current state-of-the-art GC methods employing highly specific long single capillary columns such as Petrocol-DH are being used for the analysis of gasoline-range hydrocarbons. However, the method needs many standard reference samples of respective components in a complex mixture of hydrocarbons, which limits the scope of the analytical method. The alternative approach followed by this investigation is based on the reactive method of the analysis of olefins in FCC light gasoline by subjecting them to hydrogenation and estimating the olefinic content by GC comparing the gas chromatograms of the original feed and hydrogenated product using a Petrocol-DH column. A decrease in the quantity and disappearances of the peaks are assumed as olefins, and their number and total composition is calculated. In this study the bromine number method is used to estimate the olefinic content for a comparison of results with the adopted proposed methodology. The adopted methodology quantitates olefinic content in FCC light gasoline, which is comparable with reported literature values and the bromine number method. With the availability of standard reference samples of some important major reactive olefins, the adopted methodology can also give component-wise analysis as well as total olefinic content in a single step in processes such as etherification. The methodology can be also useful in reactions in which the conversion of total olefinic content is needed such as hydration, esterification, and alkylation of olefins in a complex mixture of hydrocarbons apart from the etherification of olefins in FCC gasoline.

Journal Article↗

PubMed2001

Bioavailability studies of a new iron source by means of the prophylactic-preventive method in rats.

The bioavailability of iron from a new commercial source containing ferric gluconate stabilized with glycine sold under the trade name Bioferrico was studied in this work by means of the prophylactic-preventive test in rats. NaFeEDTA was also studied by the same methodology for comparative purposes and ferrous sulfate was used as the reference standard. The test was conducted for 4 wk with male weaned rats, which were randomized into four groups of at least eight animals each. A control group received a basal diet of low-iron content, whereas the other groups received the same diet with iron added at a dose of 20 mg/kg as FeSO4.7H2O, NaFeEDTA, and Bioferrico, respectively. Individual hemoglobin concentrations (HbC) and weights were determined at the beginning and at the end of the study and food intake was daily registered. The iron bioavailability (BioFe) of each source was calculated as the ratio between the amount of iron incorporated into hemoglobin during the treatment (HbFe) and the total iron intake per animal (ToFeIn). A relative biological value (RBV) was obtained for each iron source under study as the ratio between the BioFe of the tested compound and that of the reference standard. The RBVs were 98% and 86% for Bioferrico and NaFeEDTA, respectively. Bioferrico showed a high bioavailability and behaved inertly in relation to the sensorial properties of the fortified food when it was added to flour. These qualities emphasize Bioferrico as a promising source for iron fortification.

Animals↗

PubMed2003

Assessment by meta-analysis of PCR for diagnosis of smear-negative pulmonary tuberculosis.

We conducted a meta-analysis to assess the performance of PCR for the diagnosis of smear-negative pulmonary tuberculosis (SPT) and to identify factors that account for differences in the diagnostic accuracy of different studies. Studies published before February 2002 were included if sensitivity and specificity of PCR in smear-negative respiratory or gastric-aspirate specimens could be calculated. Analysis was conducted by using summary receiver operating characteristics models. Sensitivity and specificity ranged from 9 to 100% and from 25 to 100%, respectively. Fewer than 40% of the 50 studies reported results by number of patients, reported clinical characteristics of patients, or used as a reference standard combined culture and clinical criteria. Studies that included bronchial specimens showed higher accuracy than studies that evaluated only sputum specimens or included gastric aspirates. Studies that did not report that tests were applied blindly showed higher accuracy than those reporting blind testing. Increased sensitivity due to the use of DNA purification methods was associated with decreased specificity. Studies published after 1995, using Amplicor or dUTP-UNG, were associated with an increase in specificity at the expense of lower sensitivity. We concluded that PCR is not consistently accurate enough to be routinely recommended for the diagnosis of SPT. However, PCR of bronchial specimens could be useful in highly suspicious SPT cases. Studies not reporting blind testing are likely to overestimate accuracy of PCR. Future evaluation of PCR accuracy should be conducted by patient and type of respiratory specimen, blindly, by using a reference standard that combines culture and clinical criteria and addresses the issue of how patient characteristics affect PCR accuracy.

Humans↗

PubMed2005

Comparison of US and unenhanced multi-detector row CT in patients suspected of having acute appendicitis.

PURPOSE: To prospectively compare the diagnostic performance of ultrasonography (US) and unenhanced multi-detector row computed tomography (CT) in patients suspected of having acute appendicitis by using surgery or clinical follow-up as the reference standard. MATERIALS AND METHODS: The institutional review board approved the research protocol. Written informed consent was obtained from all patients or, for those who were adolescents, from their parents. Ninety-four patients (59 female and 35 male patients) aged 16-81 years (mean, 38 years) who were suspected of having acute appendicitis underwent both US and unenhanced multi-detector row CT of the entire abdomen. The examinations were performed within 1-2 hours of each other. US and CT images were obtained and prospectively interpreted by a different radiologist from a group of abdominal radiologists or a group of residents and general radiologists. Radiologists proposed an overall diagnosis and an alternative diagnosis. Data from US and CT were compared, and the definite diagnosis was established with surgical findings (n = 40) or results of clinical follow-up (n = 54) as the reference standard. Comparisons were made for each group of radiologists and the patient's age, body mass index (BMI), and sex. Proportion comparisons were made by using the Pearson chi2 test or the Fisher exact test. Continuous variables were compared between groups with the Mann-Whitney U test. RESULTS: Thirty patients had definite appendicitis. The sensitivity, specificity, positive and negative predictive values, and accuracy were not significantly different between US and CT or between groups of radiologists (P values ranged from .389 to >.99), regardless of the patient's BMI (P values ranged from .073 to >.99). Misclassifications were compared with the definite alternative diagnosis and were not significantly different between US and CT or between groups of radiologists (P = .061-.592), regardless of patient age (P = .875) or sex (P = .151 and >.99 for male and female patients, respectively). The frequency of inconclusive examinations, however, was significantly higher with US than with CT, regardless of radiologist experience (P = .020 and <.001, respectively). CONCLUSION: Although the diagnostic performances of US and multi-detector row CT are comparable, more inconclusive images were obtained with US.

Acute Disease↗

PubMed2002

Effect of bifidobacterium Bb12 with or without Streptococcus thermophilus supplemented formula on nutritional status.

Acute diarrhea is a common cause of infant morbidity and mortality. Probiotic supplemented infant formula is one of the effective methods for prevention of rotavirus diarrhea. Other benefits of the probiotics supplemented formula were evaluated by monitoring the growth of the children. A double-blind, placebo-controlled trial was done in 148 children aged 6-36 months. They were divided into 3 groups: the Bb12 group, 51 children received infant formula with Bifidobacteria Bb12 supplement; the Bb12+ST group, 54 children received infant formula with Bb12 and Streptococcus thermophilus supplement; and the control group, 43 children received infant formula without supplement. The mean weight Z-score according to WHO reference standard of the Bbl2 group was -1.8 +/- 0.12, the Bb12+ST group was -1.4 +/- 0.11 and the control group was -1.8 +/- 0.13 at entry. The mean weight Z-score of children after 6 month showed that the children in the Bbl2+ST group had the highest increase in weight which was increased from -1.4 +/- 0.11 to -0.9 +/- 0.12 compared to the Z-score of the Bb12 group which had increased from -1.8 +/- 0.12 to -1.2 +/- 0.13 and in the control group from -1.8 +/- 0.13 to -1.7 +/- 0.25. In terms of the mean height Z-score, the Bb12 group was -2.7 +/- 0.14 to -1.7 +/- 0.16 which was higher than the Bb12+ST group (- 2.2 +/- 0.13 to -1.7 +/- 0.13) but was not different from the control group. However, the mean weight/height Z-score of the Bbl2+ST group had approached the reference standard (Bb12 group -0.1 +/- 0.11 to -0.1 +/- 0.13, Bb12+ST group -0.1 +/- 0.10 to 0.3 +/- 0.17, control group -0.4 +/- 0.12 to -0.1 +/- 0.16). Data showed that children who received the probiotics supplement formula had better growth during the 6 month period.

Bifidobacterium↗

PubMed2001

Assessment of Crohn's disease activity by Doppler sonography of the superior mesenteric artery, clinical evaluation and the Crohn's disease activity index: a prospective study.

AIM: Recent data have shown that superior mesenteric artery (SMA) flow rates are significantly increased in active Crohn's disease, suggesting that SMA flow may be a useful, non-invasive index of disease activity. The aim of this prospective study was to evaluate the use of SMA Doppler sonography as an indicator of Crohn's disease activity and to compare with clinical evaluation and the Crohn's disease activity index (CDAI). MATERIALS AND METHODS: Patients with active Crohn's (n = 19), inactive Crohn's (n = 17) and control subjects (n = 17) were evaluated. Categorization of disease activity was based on a reference standard. CDAI scores were also calculated independently. The SMA flow parameters evaluated were resistive index, pulsatility index, end diastolic velocity, peak systolic velocity, time averaged maximum velocity, cross-sectional area and maximum flow volume. RESULTS: Using a three-group ANOVA for each of peak systolic velocity (PSV) (P = 0.01), end-diastolic velocity (EDV) (P = 0.04), pulsatility index (PI) (P = 0.003), time-averaged maximum velocity (TAMV) (P = 0.05), and maximum flow volume (TAMV.CSA) (P = 0.01), there was a significant effect of group. Using post-hoc tests, only EDV (P = 0.01), TAMV (P = 0.02) and TAMV.CSA (P = 0.003) were significantly different between active and inactive Crohn's disease, though with considerable overlap of values for EDV and TAMV. The mean CDAI scores were significantly different between patients with active Crohn's (287) and inactive Crohn's (71) (P = 0.0001) and correlated well with the reference standard. CONCLUSION: Only three of several parameters previously described as allowing Crohn's disease activity assessment actually did so in our study. However, for two of these parameters (EDV, TAMV), there was overlap between the measurements in the active and inactive groups, thus limiting the ability to discriminate disease activity in practice. The degree of overlap for maximum flow volume (TAMV.CSA) between active and inactive disease was considerably less and this parameter may be more discriminatory of disease activity. On the other hand, we found CDAI scores to be accurate in disease categorization. We agree that there appear to be hyperdynamic changes in active Crohn's disease but suggest that Doppler ultrasound assessment does not reliably assess disease activity in routine clinical practice.

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