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PubMed1994

Combination (multiple) testing for myocardial infarction using myoglobin, creatine kinase-2 (mass), and troponin T.

We retrospectively determined the mass concentrations of myoglobin, creatine kinase-2 (CK-2), and troponin T in serial samples from 80 patients with confirmed myocardial infarction (MI) and 60 non-MI patients. Results from receiver operating characteristic curve analyses show that all three tests are comparable in their diagnostic utility within the first 12 h of infarction. Decision thresholds were selected at a constant rule-in specificity of 95% and rule-out sensitivities of 95% at, respectively, 3-6, 6-9, and 9-12 h intervals after the onset of symptoms. Test sensitivities and specificities were compared for each, used as: a single test; two-test parallel combination; three-test parallel combination; two-test series combination; and three-test series combination. Our results from combination testing indicate what for the early diagnosis of MI, a single serum myoglobin measurement has diagnostic utility at 3 h after the onset of symptoms, and myoglobin and CK-2 (mass) in combination later than 3 h following the onset of symptoms. Serum troponin T is diagnostically similar to CK-2 (mass), although it has superior cardiac-tissue specificity, but it is not as yet commercially available as a "stat" test. Therefore, we recommend using troponin T as a confirmatory test 9 h after the onset of MI. Based on our findings, we suggest a testing algorithm for the early biochemical diagnosis of MI.

Adult↗
PubMedDate not supplied

Testing multiple variables on the growth of a mixed inoculum of Salmonella strains using gradient plates.

Six Salmonella strains were grown on two-dimensional sodium chloride-pH and temperature-pH gradient plates. Using image analysis the results were expressed in the form of three-dimensional wire frame graphs. On the temperature-pH gradient plates the optimum growth range was 20-30 degrees C and the minimum pH for visible growth was ca. pH 4, except for strain S. typhimurium CRA63 which grew over a narrower temperature and pH range. On the NaCl-pH gradient plates (whose NaCl gradient began at 2.75% (w/v) NaCl) the maximum concentration of salt at which growth was visible varied from 3.9% to 6.0%, and the minimum pH at which growth was observed varied from pH 4.7 to 5.4 according to the strain used. The incorporation of 0.02% (w/v) sodium nitrite reduced the maximum salt concentration and increased the minimum pH at which the strains could grow. The strains were combined and used in a mixed inoculum on NaCl-pH gradient plates containing 6 different concentrations of NaNO2 incubated at 6 different temperatures. Comparison of the data from the mixed inoculum with data from individual strains showed that, apart from one case, the mixed inoculum represented the extremes of the growth domains of the individual strains. The effect of NaNO2 on the ability of the strains to grow at different pH, NaCl concentrations and temperatures, was more clearly shown by subtracting the data of plates containing NaNO2 from the data of plates without NaNO2.

Hydrogen-Ion Concentration↗
PubMed1994

Behavioral deficits revealed by multiple tests in rats with ischemic damage limited to half of the CA1 sector of the hippocampus.

Ischemia causes neuronal necrosis in the septal half of the CA1 sector of the hippocampus in rats and produces deficits in spatial and other tasks, but the impairments are not severe. CA1-damaged rats may perform at control levels on some tests and may overlap the performance of control animals on other tests. The present study examined the performance of CA1-damaged rats on a range of tests known to be sensitive to hippocampal damage and evaluated the size of the deficit using a composite test-battery score. The rats with CA1 damage were impaired on learning set, matching to place, and latent-learning spatial navigation in a swimming pool, delayed alteration, and pattern alternation on dry land, but not on amphetamine-induced locomotion or on negative patterning. The CA1-damaged rats' impairments were mild, characterized by behavioral strategies similar to those of control rats, and their tests scores overlapped those of control rats. Nevertheless, a composite profile derived from the measures obtained from the different tests revealed a large overall impairment. The results confirm that rats with partial damage to CA1 display impairments, especially on tests that demand working memory, and suggest that the test-battery approach can be used to enhance group differences.

Animals↗
PubMed2005

Inhibition of benzo[a]pyrene induced mutagenicity and genotoxicity by black tea polyphenols theaflavins and thearubigins in multiple test systems.

This study investigated the antimutagenic and anticlastogenic effects of black tea polyphenols, theaflavins (TF) and thearubigins (TR) in Salmonella assay in vitro and in vivo in bone marrow cells of mice as measured by chromosomal aberrations (CA) and sister chromatid exchange (SCE) against a known carcinogen, benzo[a]pyrene (B[a]P). A significant decrease in mutagenicity in Salmonella assay and both CA and SCE were observed in all the different concentrations of TF and TR plus B[a]P treated series when compared with B[a]P treated group alone. These results indicate that both TF and TR have significant antimutagenic and anticlastogenic effects.

Animals↗
PubMed1997

A multiple-test study of anxiety-related behaviours in six inbred rat strains.

Recent studies have underlined the impact of genetic factors in anxiety profiles. In this context, we have initiated a series of experiments aiming to select, among six inbred strains of rats, a pair of strains that contrasts the most in fear-related behaviours measured in the open field, the elevated plus-maze, the black and white box and the social interaction test. Significant interstrain differences were found for all behavioural measures. A factor analysis of all variables produced three independent factors explaining 85.1% of the total variance. Factor 1 had high loadings from variables related to the approach/avoidance towards aversive stimuli (e.g., center of the open field, open arms of the plus-maze and white compartment of the black/white box). Variables related to general activity in novel environments (e.g., total locomotion in the open field and closed-arm entries in the plus-maze) loaded highly on Factor 2. Defecation and time of social interaction loaded positively on Factor 3. To verify whether elevated plus-maze variables loading on Factor 1 were associated to anxiety, the effects of single doses of diazepam and pentylenetetrazole were examined in Lewis and SHR rats, i.e., the most contrasting strains regarding Factor 1. Variables with high loadings on this factor changed in opposite ways in response to diazepam and pentylenetetrazole treatments. This study suggests, thus, that Lewis and SHR strains may constitute a useful model for studying the neurobiological mechanisms underlying the interindividual differences in baseline levels of anxiety.

Animals↗
PubMed1992

The order effect: reflections on the validity of multiple test presentations.

The effect of order has been previously addressed in test-retest studies but its effect on the presentation of more than one test, in the same time, is often underestimated. This study has shown that when two rating scales were given sequentially, each scored lower if received second in the pair, and that this particular form of order effect (occasion effect) was enough to affect markedly agreement on caseness when utilizing standard cut-off scores. It is therefore important that research workers not only adopt design strategies such as counterbalanced presentation, but also analyse their data for the effects of test order and position within such designs.

Bias↗
PubMed2002

Extensive multiple test centre evaluation of the VecTest malaria antigen panel assay.

To determine which species and populations of Anopheles transmit malaria in any given situation, immunological assays for malaria sporozoite antigen can replace traditional microscopical examination of freshly dissected Anopheles. We developed a wicking assay for use with mosquitoes that identifies the presence or absence of specific peptide epitopes of circumsporozoite (CS) protein of Plasmodium falciparum and two strains of Plasmodium vivax (variants 210 and 247). The resulting assay (VecTest Malaria) is a rapid, one-step procedure using a 'dipstick' test strip capable of detecting and distinguishing between P. falciparum and P. vivax infections in mosquitoes. The objective of the present study was to test the efficacy, sensitivity, stability and field-user acceptability of this wicking dipstick assay. In collaboration with 16 test centres world-wide, we evaluated more than 40 000 units of this assay, comparing it to the standard CS ELISA. The 'VecTest Malaria' was found to show 92% sensitivity and 98.1% specificity, with 97.8% accuracy overall. In accelerated storage tests, the dipsticks remained stable for > 15 weeks in dry conditions up to 45 degrees C and in humid conditions up to 37 degrees C. Evidently, this quick and easy dipstick test performs at an acceptable level of reliability and offers practical advantages for field workers needing to make rapid surveys of malaria vectors.

Animals↗
PubMed1998

Some new multiple-test procedures for dose finding.

In Tamhane, Hochberg, and Dunnett (1) we focused primarily on step-down test procedures based on contrasts among the sample means to find the minimum effective dose in a dose-response study. In the present article we use the global tests of Bartholomew (2,3) and Hayter (4) in these step-down procedures. We also propose a new step-down procedure that permits tests based on a class of contrasts [step and basin contrasts of Ruberg (5) are examples of such contrasts] that could not be used with the step-down procedures studied in our previous paper because of lack of control of the familywise error rate. A simulation study to compare the four procedures proposed in the present paper with the top four procedures from the previous article is carried out. It is found that the step-down procedure based on Bartholomew's test and the new step-down procedure based on step and modified basin contrasts generally perform better than the other procedures for a wide range of dose-response profiles.

Algorithms↗
PubMed2006

Estimation and control of multiple testing error rates for microarray studies.

The analysis of microarray data often involves performing a large number of statistical tests, usually at least one test per queried gene. Each test has a certain probability of reaching an incorrect inference; therefore, it is crucial to estimate or control error rates that measure the occurrence of erroneous conclusions in reporting and interpreting the results of a microarray study. In recent years, many innovative statistical methods have been developed to estimate or control various error rates for microarray studies. Researchers need guidance choosing the appropriate statistical methods for analysing these types of data sets. This review describes a family of methods that use a set of P-values to estimate or control the false discovery rate and similar error rates. Finally, these methods are classified in a manner that suggests the appropriate method for specific applications and diagnostic procedures that can identify problems in the analysis are described.

Computational Biology↗