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At least 1,495 records · Page 83Linked to original sources
PubMed2002

[Evaluation of TSE- and T1-3D-GRE-sequences for focal cartilage lesions in vitro in comparison to ultrahigh resolution multi-slice CT].

PURPOSE: Evaluation of TSE- and T 1 -3D-GRE-sequences for focal cartilage lesions in vitro in comparison to ultrahigh resolution multi-slice CT. MATERIALS AND METHODS: Forty artificial cartilage lesions in ten bovine patellae were immersed in a solution of iodinated contrast medium and assessed with ultrahigh resolution multi-slice CT. Fat-suppressed TSE images with intermediate- and T 2 -weighting at a slice thickness of 2, 3 and 4 mm as well as fat-suppressed T 1 -weighted 3D-FLASH images with an effective slice thickness of 1, 2 and 3 mm were acquired at 1.5 T. After adding Gd-DTPA to the saline solution containing the patellae, the T 1 -weighted 3D-FLASH imaging was repeated. RESULTS: All cartilage lesions were visualised and graded with ultrahigh resolution multi-slice CT. The TSE images had a higher sensitivity and a higher inter- and intraobserver kappa compared to the FLASH-sequences (TSE: 70 - 95 %; 0.82 - 0.83; 0.85 - 0.9; FLASH: 57.5 - 85 %; 0.53 - 0.72; 0.73 - 0.82, respectively). An increase in slice thickness decreased the sensitivity, whereby deep lesions were even reliably depicted on TSE images at a slice thickness of 3 and 4 mm. Adding Gd-DTPA to the saline solution increased the sensitivity by 10 % with no detectable advantage over the T 2 -weighted TSE images. CONCLUSION: TSE sequences and application of Gd-DTPA seemed to be superior to T 1 -weighted 3D-FLASH sequences without Gd-DTPA in the detection of focal cartilage lesions. The ultrahigh resolution multi-slice CT can serve as in vitro reference standard for focal cartilage lesions.

Animals↗
PubMed2004

Detection of small implanted tumors growing during repeated magnetic resonance imaging of the rabbit liver: application of an interpretation model.

PURPOSE: To apply experimentally and further develop a new image interpretation model based on repeated imaging and aimed at improving assessments of technical efficacy and diagnostic accuracy in the detection of small lesions. MATERIAL AND METHODS: VX2 carcinoma was implanted in the liver of 14 rabbits as two 1.1-1.7 mm3 cores. Magnetic resonance imaging was performed before and 4 days after implantation and then every second day up to the 14th to 20th day. One T2-weighted sequence (TSE T2) and three T1-weighted sequences (SE T1, GE T1, and TFL T1) were used. Interpretation was performed stepwise: three readers independently interpreted image sequences chronologically (step 1). Tumors were included at the last examination (step 2). By concurrent interpretation of repeated examinations, the earliest day at which tumors became visible and tumor size were recorded (step 3). Records were corrected (step 4) and autopsy was performed (step 5). Two procedures for use in calculating repeated detection rates of tumors with different magnetic resonance imaging sequences are presented and discussed. RESULTS: Of 40 macroscopic tumors, 34 were included. They were mainly small (size range SE T1: 1-3mm, TSE T2: 1.5-5 mm) when they became visible as determined at step 3, which was consistently earlier than observed at step 1. TSE T2, SE T1, and GE T1 did not differ significantly regarding earliest day of detection (step 3), while TFL T1 revealed the tumors later. The initial repeated detection rates were higher with TSE T2 than with the other sequences. Frequency of false positives varied over time, indicating fluctuating criteria for reporting tumors. CONCLUSION: A theoretical image interpretation model previously described proved to be applicable for detection of experimental liver tumors. The model was improved by introducing calculations of repeated detection rates for initial image interpretation using an imaging reference standard.

Animals↗
PubMed2002

[Evaluation of an ELISA kit made in our laboratory for intratypic discrimination of poliovirus type 1 strains isolated from acute flask paralysis].

In this study, we aimed to develop and evaluate an enzyme based immunological method (ELISA) for the intratypic differentiation (whether if Sabin like-SL, or non Sabin like/wild type-NSL) of poliovirus type 1 isolates, in the frame of Polio Eradication Programme (PEP) in Turkey. Five poliovirus type 1 strains which were formerly isolated and identified in our laboratory from fecal samples of acute flask paralysis (AFP) patients, and standard reference strains of vaccine type 1 and prototype wild (Mahoney) polioviruses have been tested into plate wells that bounded with 5 different monoclonal antibodies (mAbs B18, S2-36, M18, B82, M49). The wells which gave high absorbance than cutoff value estimated by comparing negative control wells, were accepted as positive. As a result, the standard poliovirus strains were differentiated correctly, whereas 2 patient isolates were identified as SL and 3 were NSL. In conclusion, our home-made ELISA method found to be successful for intratypic differentiation of poliovirus type 1 isolates, however more detailed studies are necessary in order to increase the susceptibility and specificity of this test.

Acute Disease↗
PubMedDate not supplied

The rapid decomposition of biological materials by using a microwave acid digestion bomb.

A microwave acid decomposition technique was evaluated for decomposing biological standard reference materials (NBS oyster tissue and bovine liver) for trace metal analyses. Dissolution consisted of HNO3 decomposition in a closed Teflon bomb. A microwave oven was used as the heat source. Complete decomposition times were less than 1 min. Resulting solutions were analyzed by atomic absorption spectrophotometry for Cd, Cu, Fe, Pb, and Zn. Recoveries were estimated by comparison with National Bureau of Standards certified values. The precision and accuracy of the results ranged from 1 to 13% and 93 to 106%, respectively.

Animals↗
PubMed1989

[Erythropoiesis and erythrocytes in children, physiology and standards].

Foetal erythropoiesis has its own particularities: it takes place mostly in the liver for a long time, is macrocytic and is strongly stimulated, then suppressed at birth; the level of haemoglobin F, which has specific properties, is still high at birth. In children, the site of sampling must be clearly indicated in view of possible discrepancies between capillary and venous blood samples. Hemoglobin levels and red cell indices vary with age, and it is indispensable to take as reference standards that change in each period of life from foetal life to adolescence. The polycythaemia and macrocytosis observed at birth is followed by a period when the haemoglobin level is relatively low and microcytosis develops. Adult values will be reached gradually during the second part of childhood.

Age Factors↗
PubMed2001

Discriminatory power of 3.5 MHz convex and 7.5 MHz linear ultrasound probes for the imaging of traumatic splenic lesions: a feasibility study.

BACKGROUND: Ultrasound is a powerful tool for recognition of free fluid after blunt abdominal trauma, whereas its role for detection of organ lesions remains to be defined. The objective of this study was to determine the diagnostic value of different ultrasound transducers for the precise detection of visceral damage rather than its surrogates in case of splenic injury. METHODS: After a standardized focused abdominal sonogram for trauma protocol to screen for hemoperitoneum, 37 slim, hemodynamically stable subjects with suspected torso trauma were investigated for the extent of parenchymal lesions of the spleen using a 3.5 MHz curved array and a 7.5 MHz linear device. Helical computed tomographic scanning was carried out as the reference standard in all cases. RESULTS: Twenty patients presented splenic damage. The 7.5 MHz transducer showed higher accuracy than the lower frequency probe for the detection of tissue irregularities (difference in proportions, 16.2%; 95% confidence interval, -1.9%-33.5%). A similar trend was observed for 13 lacerations subsequently progressing to two-timed splenic rupture that required surgery (absolute risk reduction, 8.1%; 95% confidence interval, -7.6%-23.9%). With an observed prevalence of 54% for the presence of splenic injury, organ lacerations could be excluded more confidently using the linear probe (posttest probability, 16% vs. 36%). CONCLUSION: In slim patients, higher frequency linear ultrasound probes can provide therapy-relevant information on the integrity of splenic parenchyma after blunt abdominal trauma.

Abdominal Injuries↗
PubMed1996

Detection of methamphetamine in sweat by EIA and GC-MS.

Sweat was collected with the PharmChekTM sweat patch and drugs were eluted from the collection pad of the patch. A solid phase, enzyme immunoassay using microtiter plates was modified for analysis of methamphetamine in sweat. After methamphetamine administration, sweat contains primarily parent methamphetamine. The immunoassay was determined to have crossreactivity relative to 100% for the methamphetamine (MA) calibrators; to 144% for methylenedioxymethamphetamine (MDMA); to 30% for d-amphetamine; to 21% for methylenedioxyamphetamine (MDA); and to 8% for I-methamphetamine. The optimum cutoff concentration for this modified assay was determined by receiver operating characteristic analysis to be 10 ng/mL amphetamine equivalents. At this cutoff concentration the assay had a diagnostic sensitivity of 84.5% and a diagnostic specificity of 93.2% versus gas chromatography-mass spectrometry (GC-MS). The positive predictive value at a prevalence of 50% was 86%. The intra-assay precision at 10 ng/mL was 9.9% (coefficient of variation, CV) and the interassay CV was 13%. Analysis of spiked patches at plus or minus 25 and 50% around the cutoff gave a percent positive threshold of approximately 50% at a cutoff of 10 ng/mL and a 95% confidence level for a positive result by the EIA between 15 and 20 ng/mL. Of 18 potential adulterants that might be injected into or under the patch, two (tile cleaner and cough syrup) caused a false-positive response by immunoassay. All results were confirmed by GC-MS. The clinical sensitivity and specificity of the overall analysis system (sweat collection and analysis) were 85 and 100%, respectively, using known methamphetamine dosing of volunteers (10, 20, and 25 mg) as the reference standard.

Calibration↗
PubMed1990

Impact of protein measurements on standardization of assays of apolipoproteins A-I and B1.

In 1989 the Committee on Apolipoproteins of the International Federation of Clinical Chemistry and the Centers for Disease Control conducted an international survey of total-protein measurements of isolated low-density lipoproteins (LDL) and delipidated high-density lipoproteins (HDL), and of their relationships to the National Institute of Standards and Technology (NIST) bovine serum albumin (BSA) Standard Reference Material (SRM). Most of the 93 apolipoprotein laboratories surveyed use the Lowry total-protein method. Results reported with the LDL preparations demonstrated a large bias and variation among methods; those with delipidated HDL were not as great, but were similar to those for BSA. Performance improved appreciably with use of the Lowry-sodium dodecyl sulfate method and the NIST BSA SRM for protein measurement. The total CVs, including among-laboratory and within-laboratory errors, averaged approximately 50% and 23% for LDL, 17% and 11% for HDL, and 18% and 11% for BSA solutions by all methods and by the Lowry methods, respectively. Regardless of the methods used, greater variability of the protein measurements was seen with the normally occurring LDL than with the nonlipoprotein BSA or delipidated HDL. The mean CV values for all samples among laboratories averaged between 10% and 15% with the modified Lowry methods; the biuret method gave the highest among-laboratory CV, 34%; the Kjeldahl had the lowest, 7.7%. Use of the same methodology and primary nonapolipoprotein standard is essential for comparability of protein results for apolipoprotein primary standard solutions. This is especially true for apolipoprotein B, because its inherent properties and lability make protein analysis difficult. This study supports the use of a standardized selected Lowry-sodium dodecyl sulfate method traceable to quantitative amino acid analysis as a point of reference for determining the protein concentration of primary calibration reference materials for apolipoproteins.

Apolipoproteins A↗
PubMed2006

[Quality analysis and evaluation of Rhizoma Coptidis under different cultivation conditions].

AIM: To develop methods for the fingerprint analysis of Rhizoma Coptidis and the determination of berberine, palmatine and jatrorrhizine in Rhizoma Coptidis, and analyze the contents of these three alkaloids in Rhizoma Coptidis under different cultivation conditions, from different areas and processed with different methods. METHODS: Two methods (HPLC-UV and HPLC-MS) have been developed and used in fingerprint analysis of Rhizoma Coptidis. An HPLC method was used to determine the contents of three alkaloids. RESULTS: With HPLC-MS techniques, seven major chromatographic peaks in the fingerprint analysis of Rhizoma Coptidis were identified by their MS spectra and compared with the reference standards. In different cultivation conditions, shading conditions and growing ages have obvious influence on the contents of three alkaloids in Rhizoma Coptidis, while planting density was not the major factor that influenced the contents of three alkaloids. The contents of three alkaloids of Coptidis samples were almost higher than those of Coptidis reference material. For Coptidis samples from different cultivation area, the contents of these three alkaloids were different greatly. For Coptidis samples processed with different methods, the contents of three alkaloids were not influenced obviously by processing methods. CONCLUSION: The results showed that the ecology cultivation method to replace the traditional shading method was feasible and provided the theoretical foundation for scientifically processing Rhizoma Coptidis.

Berberine↗
PubMed1997

Synthesis of quantitation standards for nested competitive PCR for the determination of minimal residual disease in B-lineage acute lymphoblastic leukaemia.

Quantitative PCR-based assays of leukaemic cells in remission marrow hold promise for therapeutic guidance, but are not yet sufficiently reliable for clinical application. For B-lineage ALL, these assays usually involve PCR of clonal somatic gene rearrangements of the immunoglobulin heavy chain gene. The most accurate quantification can be achieved by competitive PCR. Here we present a novel approach for the production of reference standards for use in nested competitive PCR of these gene rearrangements, which might enable more reliable assessment of MRD for prognosis and selection of patients for individualised therapy.

Binding, Competitive↗
PubMed1999

Empirical evidence of design-related bias in studies of diagnostic tests.

CONTEXT: The literature contains a large number of potential biases in the evaluation of diagnostic tests. Strict application of appropriate methodological criteria would invalidate the clinical application of most study results. OBJECTIVE: To empirically determine the quantitative effect of study design shortcomings on estimates of diagnostic accuracy. DESIGN AND SETTING: Observational study of the methodological features of 184 original studies evaluating 218 diagnostic tests. Meta-analyses on diagnostic tests were identified through a systematic search of the literature using MEDLINE, EMBASE, and DARE databases and the Cochrane Library (1996-1997). Associations between study characteristics and estimates of diagnostic accuracy were evaluated with a regression model. MAIN OUTCOME MEASURES: Relative diagnostic odds ratio (RDOR), which compared the diagnostic odds ratios of studies of a given test that lacked a particular methodological feature with those without the corresponding shortcomings in design. RESULTS: Fifteen (6.8%) of 218 evaluations met all 8 criteria; 64 (30%) met 6 or more. Studies evaluating tests in a diseased population and a separate control group overestimated the diagnostic performance compared with studies that used a clinical population (RDOR, 3.0; 95% confidence interval [CI], 2.0-4.5). Studies in which different reference tests were used for positive and negative results of the test under study overestimated the diagnostic performance compared with studies using a single reference test for all patients (RDOR, 2.2; 95% CI, 1.5-3.3). Diagnostic performance was also overestimated when the reference test was interpreted with knowledge of the test result (RDOR, 1.3; 95% CI, 1.0-1.9), when no criteria for the test were described (RDOR, 1.7; 95% CI, 1.1-2.5), and when no description of the population under study was provided (RDOR, 1.4; 95% CI, 1.1-1.7). CONCLUSION: These data provide empirical evidence that diagnostic studies with methodological shortcomings may overestimate the accuracy of a diagnostic test, particularly those including nonrepresentative patients or applying different reference standards.

Bias↗
PubMed1982

HLA-SB in the south of France. Correlation between locally derived and reference typing reagents.

The HLA-D region of the Major Histocompatibility Complex has been subdivided since 1978 (Mawas et al. 1978) into two subregions separable by recombination: a telomeric subregion (closer to HLA-B), coding for the classical HLA-DR or Dw specificities (Mawas et al. 1980) as well as for the more recent MT series (Park et al. 1980); and a centromeric subregion (closer to GLO), coding for a new series of alleles provisionally named SB (for secondary B cell antigens) (Shaw et al. 1980, 1981a). Reagents allowing the identification of six independent alleles have been characterized in two laboratories (Charmot et al. 1980 and Shaw et al. 1980, 1981b) using the technology of primed lymphocytes typing (Sheehy et al. 1975; Mawas et al. 1975). The existence of this new locus is supported by the following arguments: population studies by Shaw demonstrating five traits distinct from DR behaving as alleles (Shaw et al. 1981b), analysis of two informative SB/DR recombinant families (Mawas et al. 1978; Mawas et al. 1980; Shaw et al. 1981a), and, finally, studies of mutants showing independent loss of DR expression without loss of SB expression (Kavathas et al. 1981). The present report summarizes the HLA-SB typing of 109 unrelated individuals from the South of France and segregation studies in 14 unrelated families; a first attempt to correlate local "SB" reagents with the NIH reference standards is presented.

Female↗
PubMedDate not supplied

Drugs and related topics.

Drugs is a topic that was certainly an issue of discussion at this year's annual meeting. This Committee had the responsibility of organizing a half day symposium on "Pharmaceutical Authenticity and Safety" that took place September 12, 2005. This symposium aims at improving the critical points in the analytical pharmaceutical field related to traceability assessment, use of certified reference materials (CRMs), and proficiency testing implementation to get the highest quality of the obtained results. Recognized experts presented these topics. Also, other complementary subjects, such as the application of advanced analytical technologies to reach the authenticity and safety of the pharmaceutical drugs and drug products, their microbiological quality assessment, without disregarding an important topic such as sampling, was presented and discussed. The talks that were presented are the following: "Proficiency Testing as a Need in the Pharmaceutical Field," Arlene Fox (AOAC INTERNATIONAL, Gaithersburg, MD); "Implementation of Traceability in the Pharmaceutical Laboratory," Thomas Layloff, (Management Sciences for Health, Arlington, VA); "Harmonized Characteristics of Certified Reference Materials According to ISO Guides-Attractive also for Pharmaceutical Analysis," Hendrik Emons (Reference Materials, Unit Institute for Reference Materials and Measurements (IRMM), Joint Research Centre European Commission, (Geel, Belgium); "Importance of LC/MS/MS for the Fingerprinting of Pharmaceutical Drugs," Paul A. Steinberg, (Thermo Electron Corp., Woodstock, GA); "Process Analytical Technology (PAT) as a Way for Better Manufacturing and Quality Assurance," John F. Kauffman (Division of Pharmaceutical Analysis, U.S. Food and Drug Administration (St. Louis, MO); "Stability Testing for the Safety Assessment of Pharmaceuticals," Marta Vidal (Boeringher Ingelheim Argentina, Buenos Aires, Argentina); "Validation of Microbiological Methods for Sterile and Nonsterile Pharmaceutical Products," Michael Brodsky (Brodsky Consultants, Thornhill, ON, Canada); "The Relationship Between Pharmacopoeial Reference Standards and ISO REMCO Initiatives and Guides," Ronald G. Manning (United States Pharmacopoeia, Rockville, MD).

Calibration↗
PubMedDate not supplied

Separation of pH, dilution, ionic strength and chemical matrix effects for biological monitoring of urines with the Microtox test using nicotine, cotinine and reference urines.

The aim was to investigate the factors influencing light emission from Photobacterium phosphoreum in the Microtox test to interpret bioassay results for urine. Four reference urines were assessed as reference materials for the bioassay. Nicotine and cotinine were investigated as urinary markers for tobacco exposure. The optimum luminescence conditions were: 1.85%-3.25% NaCl, 0.33-0.58 mol/L ionic strength, and pH 5.8-6.7. Low pH values and high concentration of toxic trace metals were important factors in this study. Unexpected toxicity for a Standard Reference Material was attributed to zinc contamination. Nicotine and cotinine together exhibited antagonistic effects in 2% saline but this could not be observed in the urines because of substantial urine toxicity. Thus practical urinary biological monitoring with the Microtox test necessitates excretion of metabolites and compounds that are much more toxic than the urine components. Also, separation of the effects of physical factors like pH, ionic strength and dilution is essential before chemical toxicity effects can be assigned. This is the first report of Microtox EC50 values for nicotine and cotinine. The results have application to environmental samples since analyses are often uncontrolled relative to pH, ionic strength and dilution.

Biological Assay↗
PubMed2004

Predicted peak expiratory flow: differences across formulae in the literature.

The study objectives were to examine the differences between Peak Expiratory Flow (PEF) formulae in the literature and to assess the potential impact of those differences on the interpretation of clinical guidelines for asthma management. We calculated 100% PEF values for hypothetical patients at the 50(th) percentile for height and weight and classified the percent predicted PEF into severity groups according to national asthma guidelines. Choosing different formulae could give an 18 year old man a 100% predicted PEF as low as 501 L/min and as high as 730 L/min (delta = 229 L/min); and a 35 year old woman a classification of severe (46%) using one, but moderate (57%) using another. Predicted PEF varied widely across formulae and choice of formula may alter guideline-based care. We propose recently published population-based equations as the reference standard for future asthma guidelines.

Adolescent↗
PubMed2006

Accurate mass determination of organotrifluoroborates.

Exact mass measurements were obtained for a variety of potassium- and tetra-n-butylammonium organotrifluoroborates using commercially available organic sulfate salts as internal reference standards. Accuracies were determined within 5 ppm using a sector ESI mass spectrometer operating in the negative ionization mode.

Borates↗
PubMed2003

Special Topics III: bias.

Researchers, manuscript reviewers, and journal readers should be aware of the many potential sources of bias in radiologic studies. This article is a review of the common biases that occur in selecting patient and reader samples, choosing and applying a reference standard, performing and interpreting diagnostic examinations, and analyzing diagnostic test results. Potential implications of various biases are discussed, and practical approaches to eliminating or minimizing them are presented.

Bias↗
PubMedDate not supplied

Are age-specific reference ranges for prostate specific antigen population specific?

INTRODUCTION: At present PSA is Considered to be the leading screening test for prostate cancer. We determined whether in men 60 to 79 year old with a serum prostate specific antigen (PSA) within age specific PSA reference ranges prostate biopsy could be safely eliminated. METHODS: We retrospectively analysed all 60-79 year old men who had undergone radical perineal prostatectomy (RPP) for prostate cancer (CaP) at our institution. All patients had undergone prostate biopsy following an abnormal rectal examination and/or PSA greater than 4.0 ng/ml. We compared our results using the standard reference range of 0 to 4.0 ng/ml with those we had obtained using the age specific PSA reference ranges of Oesterling et al. RESULTS: 204 men between 60-69 years and 67 men between 70-76 years had undergone RPP for CaP. Applying age specific PSA reference ranges 56 CaP would have been overlooked. Of those 46% had a favourable histology. Taken together 54% of the cancers overlooked had an unfavourable histology. CONCLUSION: In contrast to previous reports of unfavourable histological characteristics in only 5-24% of missed cancers, applying age specific PSA reference ranges, 54% of missed cancers in our patients exhibited an unfavourable histology. We therefore conclude that age specific PSA reference ranges did not safely eliminate the need for prostate biopsy in our study population.

Age Factors↗