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PubMed1979

Statistical analysis of method comparison data. Testing normality.

A Lilliefors test of normality has been applied to data from precision and accuracy studies. Most data sets tested as non-normal. Simulation studies showed that the test is extremely sensitive to the rounded, narrowly distributed data that are typical of method performance studies in clinical chemistry. The Lilliefors test can be modified to be applicable to rounded data so that it gives fewer indications of non-normality. The authors conclude that the selection of a test of normality requires careful study of the properties of the test. Otherwise, the subsequent choice between parametric and nonparametric statistics may not be meaningful.

Chemistry, Clinical↗
PubMed1990

Detection of human T-cell leukemia virus type I (HTLV-I) provirus in an infected cell line and in peripheral mononuclear cells of blood donors by the nested double polymerase chain reaction method: comparison with HTLV-I antibody tests.

Human T-cell leukemia virus type I (HTLV-I) provirus DNA from the cultured cell line HUT 102 and from peripheral mononuclear cells (PBMC) of anti-HTLV-I antibody-positive Japanese blood donors was detected by the nested double polymerase chain reaction (PCR) method. This procedure consists of a first amplification and a second amplification with the products of the first amplification and primers interior to the first primers. Using this method, we demonstrated that it is possible to detect single-template DNA. Polyacrylamide gel electrophoresis of the nested double PCR products, with our primers, revealed three bands with excess amounts of template DNA, two bands with moderate amounts, and a single band with limited amounts. The amount of provirus in PBMC was roughly estimated from the results of the nested double PCR. Particle agglutination (PA) assays and indirect immunofluorescence testing (IF) with mixed MT-2 cells and Molt-4 cells as targets to detect anti-HTLV-I antibody were performed, and the results were compared with those of the nested double PCR of the pX region. None of the 101 PA-negative samples were positive in either the IF or PCR test. Of the 155 samples that were antibody positive by the PA assay, 57 were positive by both PCR and IF. Furthermore, the results of the IF and PCR tests coincided completely. It was therefore concluded that the IF method is most appropriate for confirmation of the PA assay currently used in most diagnostic laboratories and blood centers.

Base Sequence↗
PubMedDate not supplied

A taxonomy of clinical research methods: comparisons of family practice and general medical journals.

Although an understanding of research methodology has been identified as an important skill for family practice researchers, the available literature contains confusing terminology and lacks agreement about research design classifications. A multidimensional taxonomy is presented to clarify and simplify the understanding of research designs, data collection methods, and research populations for family practice researchers. The taxonomy was used to classify 103 articles from five medical journals. Compared with general medical journals, reports in family practice journals used similar research designs but were more likely to rely on self-report data and to draw subjects from outpatient populations.

Data Collection↗
PubMed1990

Cytokinetic investigation of lung tumors using the anti-bromodeoxyuridine (BUdR) monoclonal antibody method: comparison with DNA flow cytometric data.

In order to investigate the cytokinetics of malignant tumors and non-malignant lesions of the lung, tissue samples from 57 patients affected by non-small-cell carcinoma (NSCLC), small-cell carcinoma (SCLC), and benign and inflammatory lesions have been analyzed using the BUdR monoclonal antibody (MAb) method. This method is based on the preparation, at the time of surgery, of viable monocellular suspensions (using collagenase and DNase treatment) and the concomitant administration of BudR. The percentage of BudR-labelled cells was monitored by fluorescent microscopy using an FITC-labelled second antibody. In NSCLC, each histological group showed a wide range of labelling index (LI) values. On the contrary, SCLC exhibited a more homogeneous kinetic behaviour as evidenced by a narrowly distributed, higher LI. Tumors shown to be diploid by flow cytometry did not show a lower LI than aneuploid tumors. Furthermore, differences were constantly observed between the S-phase percent calculated using BUdR and that calculated using the DNA flow cytometric (FC) histogram, the latter always showing higher S-phase values. In an attempt to study the intra-tumor proliferative heterogeneity, multiple-site sampling was performed. Proliferative heterogeneity seemed to be higher inter-tumor than intra-tumor. Finally, a positive correlation (p less than 0.05) was found between LI and the actual doubling time (DT) of the primary tumor mass, evaluated using sequential radiographs. In conclusion, the present BUdR method can be considered a useful source of relevant information on in vivo cell growth, in parallel to other clinical (DT) and biological (DNA content) approaches.

Adenocarcinoma↗
PubMed1991

Subjective visual echocardiographic estimate of left ventricular ejection fraction as an alternative to conventional echocardiographic methods: comparison with contrast angiography.

Left ventricular ejection fraction (LVEF) is a measure of ventricular function with clinical and prognostic significance and can be reliably calculated with various M-mode and two-dimensional echocardiographic formulas in selected, good quality echocardiograms. Subjective visual echocardiographic estimate of LVEF is a potentially less time consuming and more widely applicable method. In order to test its reliability, we performed a prospective blind trial in 40 consecutive patients undergoing biplane contrast ventriculography (BCV), to compare the visual estimate of LVEF during a complete echocardiogram of three independent observers with (1) cubed M-mode formula, (2) Teichholz M-mode formula, (3) length-area method from the four-chamber view, and (4) Simpson's single plane formula. BCV was the reference method. The best correlation with BCV was obtained by visual estimate [r of the three observers, respectively = 0.75; 0.84; 0.81] and M-mode measurements [r (1) = 0.8; r (2) = 0.8], but the most sophisticated methods provided the poorest estimate [r (3) = 0.54; r (4) = 0.49]. All correlation coefficients improved when good studies, defined as a definition of the endocardial surface of more than 75%, were selected (n = 23), but the differences persisted. One observer systematically estimated higher values than the other two (Friedman's test, p less than 0.01) and this interobserver variability suggests that each echocardiographer should test himself against BCV in his lab in order to apply the visual estimate method reliably.

Adult↗
PubMed1990

Determination of anti-ds-DNA antibodies by three different methods: comparison of sensitivity, specificity and correlation with lupus activity index (LAI).

Ninety-seven sera, 58 from patients with SLE and 39 from patients with other autoimmune rheumatic diseases were tested for anti-ds-DNA antibody activity by ELISA, Farr, and Crithidia Lucilliae assays. Fifty-six per cent of the sera were positive by at least one method. Eighty per cent of the SLE population was positive by ELISA, 39% by Farr Assay and 33% by the Crithidia assay. Crithidia assay exhibited the greater specificity (100%) followed by the Farr Assay (97%) and the ELISA (80%). Sera positive by all methods showed a significantly higher mean value of the ELISA rates, than sera positive only by ELISA (p less than 0.001). When the SLE sera were analyzed according to disease activity, it was shown that ELISA and Farr Assay correlated well with the lupus activity index (LAI) (r less than 0.001). The SLE sera with the higher anti-ds-DNA concentration (sera positive by all 3 methods) did not correlate with LAI when tested by the Farr Assay (0.05 less than p less than 01) in contrast to the ELISA values, which correlated very well (p less than 0.01). Our results indicated that the ELISA is the most sensitive method with reasonable specificity as well. In addition, the ELISA anti-DNA values correlate with the clinical activity of lupus, independently of the anti-ds-DNA levels in the sera. The latter should be attributed to the fact that this method detects all the heterogenous population of anti-ds-DNA.

Antibodies, Antinuclear↗
PubMed1986

Ultrastructural observation of alpha-fetoprotein producing cells in human hepatocellular carcinoma using immunoperoxidase methods--comparison with fetal liver.

The precise sites of alpha-fetoprotein (AFP) synthesis and ultrastructural features and differences of AFP-producing cells were observed in periodate-lysine-paraformaldehyde fixed, frozen liver tissues from four human hepatocellular carcinoma (HCC) patients and three human fetuses using the direct (horseradish peroxidase-labeled Fab' fraction of anti-human AFP) immunoperoxidase method. We demonstrated that AFP was located in the membrane and cisternae of rough endoplasmic reticulum, membrane-bound ribosomes, perinuclear space and Golgi apparatus. The location and intensity of immunoreaction products of AFP in hepatoma cells varied from cell to cell and case to case, while these features tended to be regular in fetal hepatocytes. We did not observe ultrastructural differences between AFP-producing and non-producing cells adjacent to each other. These observations indicate that AFP production does not occur in morphologically distinct cell populations of hepatoma tissue and that hepatoma tissue is functionally much more heterogeneous than fetal liver.

Aged↗
PubMed1976

Usefulness of the group-comparison method to demonstrate sex differences in spatial orientation and spatial visualization in older men and women.

This paper reports an analysis of sex differences in cognitive test scores covering the dimensions of spatial orientation and spatial visualization in groups of 6 older men and 6 women matched for speed of performance on a maze test and level of performance on a spatial relations task. Older men were more proficient solving spatial problems using the body as a referent, whereas there was no significant difference between the sexes in imagining spatial displacement. Matched comparisons appear a useful adjunct to population research to understand the type(s) of cognitive processes where differential performance by the sexes is observed.

Age Factors↗
PubMed1990

Stroma-free hemoglobin solutions prepared by crystallization and ultrafiltration methods; comparison of composition and coronary vasoconstrictor potency.

Stroma-free hemoglobin solutions (SFHS) were prepared by the crystallization and ultrafiltration methodologies. The preparations were partially characterized with respect to their effects upon the isolated perfused rat heart. SFHS prepared by ultrafiltration is characterized by a substantially lower content of residual membrane phospholipid and a more restricted protein composition. This preparation is also essentially free of vasoconstrictor and contractility-depressant actions on the ex vivo perfused heart. In contrast, crystallization-produced SFHS is less well purified of both phospholipid and protein constituents, is likely to generate denatured protein aggregates during storage and exhibits vasoconstrictor and contractility-depressant activity which may vary significantly, from batch to batch. These findings indicate that preparative methodology based on ultrafiltration and size-exclusion, yields SFHS which is superior in these respect to that produced by a crystallization method.

Animals↗
PubMedDate not supplied

A multi-allergen ELISA screening method. Comparison with Pharmacia CAP system and Phazet skin prick test.

Eighty consecutive subjects, coming to our service as suffering from conjunctivitis and/or rhinitis and/or asthma, were investigated by a new multi-allergen enzymatic screening immunoassay (Profilo, Bio-Allergy, Rome, Italy) regarding to serum specific IgE for groups of inhalant allergens (Dermatophagoides, Parietaria, grasses, trees, animal danders). These groups include allergens which are most frequently responsible of allergy in our country. Indices of diagnostic accuracy of this assay were analyzed in relation to skin prick test (SPT, Phazet, Pharmacia), as in vivo reference test, and Pharmacia CAP System, as in vitro reference test, comparing the results achieved by these tests in the same group of subjects. Profilo showed high significant (p < 0.0005) correlations and satisfactory indices of diagnostic accuracy (sensitivity, specificity, predictive values of positive and negative, and efficiency) for the tested allergens with reference to both Phazet SPT and CAP System. In addition, the method appeared very rapid and simple, so that it could be performed in the physician's office.

Adolescent↗
PubMed1992

Determination of hippocampal protein kinase C using a frozen tissue method: comparison of synaptosomal and total activity in C57BL/6 and DBA/2 mice.

A slow freeze/fast thaw tissue preparation gave analogous hippocampal protein kinase C (PKC) activity to a fresh tissue preparation in both C57BL/6 and DBA/2 mice. Both the frozen and fresh preparations demonstrated a 28% reduction in membrane-bound PKC activity in DBA compared to C57 mice which supports our previous findings (14). This DBA-associated reduction was found only in total PKC and not synaptosomal PKC activity suggesting that the PKC difference between C57 and DBA mice may be primarily postsynaptic. This investigation shows that (1) PKC activity obtained from a slow freeze/fast thaw preparation is analogous to activity obtained from fresh tissue and (2) analysis of PKC activity in both a total and synaptosomal preparation may provide additional characterization of PKC differences such as that observed between C57 and DBA mice.

Animals↗
PubMed1989

[Quantitation of plasma 17-beta estradiol using an immunoenzyme method. Comparison with a specific radioimmunoassay].

Estradiol-17 beta (E2) was assayed on plasma samples with an enzyme immunoassay kit and results were compared with values obtained from a specific radioimmunoassay. An overall and specimen-dependent underestimation is found, confirmed by cold E2 recovery experiments. Such a kit is not entirely reliable in ovulation induction monitoring, specially for definition of hCG administration timing.

Chorionic Gonadotropin↗