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PubMed2003

Virtual microscopy as a tool for proficiency testing in cytopathology: a model using multiple digital images of Papanicolaou tests.

BACKGROUND: Modern digital cameras can acquire images from cytologic slides at sufficient resolution to allow for digital enlargement and scrolling on a video monitor, allowing for the simulation of microscopy using a computer. OBJECTIVE: The purpose of this study was to develop a tool for proficiency testing in cytopathology using multiple digital images of Papanicolaou tests. METHODS: Nine images were photographed from each of 10 Papanicolaou tests at x100 optical magnification, 3400 x 2300-pixel resolution, using a light microscope and a digital camera. All images from each case were tiled in a single canvas with Photoshop 4.0 software. Two cytopathologists and 3 cytotechnologists interpreted these "virtual slides" using a computer and graded diagnostic codes (PAP program, College of American Pathologists). Subjects were retested a year later using the glass slides from the same cases and routine microscopy. Both test results, by diagnostic code, were compared with the McNemar test of symmetry. RESULTS: The 5 test subjects provided 42 and 50 correct diagnostic codes by "virtual microscopy" and light microscopy, respectively. No significant asymmetry in results obtained by virtual microscopy and light microscopy was encountered with the McNemar test of symmetry. All test answers were correctly classified by selection series, using both virtual microscopy and light microscopy, and the responses would have been graded as 100% by current PAP program scoring guidelines. This suggests that virtual microscopy could be used for proficiency testing purposes. CONCLUSIONS: A simple virtual microscopy method designed to challenge participants to locate and diagnose cells of interest was effective for the administration of standardized proficiency tests. Virtual microscopy methods that rely on single-plane images to locate and diagnose cells of interest could provide effective proficiency testing tools prior to the development of more computationally intensive systems that represent an entire Papanicolaou test at multiple focal planes.

Computer Simulation↗

PubMed1986

The ovine corticotropin-releasing hormone stimulation test and the dexamethasone suppression test in the differential diagnosis of Cushing's syndrome.

We gave a standard dexamethasone suppression test and an ovine corticotropin-releasing hormone (CRH) stimulation test to 41 patients with adrenocorticotrophic hormone (ACTH)-dependent hypercortisolism to determine the efficacy of each test in the differential diagnosis of Cushing's syndrome. Twenty-nine of thirty-three patients with Cushing's disease and 0 of 8 patients with ectopic secretion of ACTH responded to the ovine CRH test with increased levels of cortisol. When a cortisol response was judged as positive for Cushing's disease, the CRH test had a diagnostic sensitivity, specificity, and accuracy of 88%, 100%, and 90%, respectively. Twenty-nine patients with Cushing's disease and 1 patient with ectopic secretion of ACTH responded to the dexamethasone suppression test. A combined-test strategy requiring negative results from both tests to exclude a diagnosis of Cushing's disease yielded superior sensitivity (100%) and diagnostic accuracy (98%). Thus, the ovine CRH test works as well as the standard dexamethasone suppression test in discriminating between Cushing's disease and ectopic ACTH secretion. The diagnostic power of each test is enhanced when the two tests are combined.

17-Hydroxycorticosteroids↗

PubMed1999

[Psychosocial consequences of presymptomatic genetic testing. A retrospective study of testing for Huntington disease].

We studied the psychological impact and psychosocial consequences of direct presymptomatic testing for Huntington's disease in Norway. We interviewed 30 out of a total of 43 persons at risk for Huntington's disease who had been tested one to three years earlier, and had been through the test program, and 19 of their spouses. We also included 16 persons at risk who had decided not to take the test. 22 persons were non-carriers, and seven carriers. One had decided not to know the answer so far. 13 out of 30 answered that the risk of getting Huntington's disease had influenced choices they had made in their lives, but quite a few did not know that they were at risk before they had grown up. Six couples out of 21 had divorced after the test; only three said it happened because of the test result. The main problem for many of the persons who now know they are non-carriers is that siblings already are sick or know they will get the disease. 15 persons (50%) experienced the need for some kind of psychiatric treatment during the pre-test period, during the test procedure, or after the test. Eight persons said they had wanted a closer follow-up after the test; most of them had got a negative answer. In this study most of those at risk had adapted reasonably well to the test results. Only seven persons out of 30 were found to be carriers in our study. We therefore have reason to believe that among the 13 tested persons who declined to be involved in the study, the majority had been identified as carriers. Our findings may lend support to a hypothesis suggesting two kinds of response to being identified as carrier. According to studies of post-traumatic stress disorders, one group adjusts reasonably well. The other group responds by avoiding follow-up contact with professional teams, which suggests more psychosocial pain and distress.

Adaptation, Psychological↗

PubMed1999

Poultry vaccines: an analysis of the animal trials required for vaccine testing and the way to reduce or refine these tests.

The testing of vaccines for use in chickens requires a large number of animal trials. Especially for poultry vaccines, quality testing of each batch consists of testing for extraneous agents in chickens for all products and potency tests for inactivated products. For the licensing of a vaccine a number of safety and efficacy tests is necessary. The safety testing covers dose and overdose studies, and the influence on reproductive performances and immunological functions. For live vaccines some additional trials concerning spread of vaccine strains, dissemination in the vaccinated animals and reversion to virulence are required. Some possibilities for combining several tests are presented. The purpose is to reduce the number of animals needed in these trials. The efficacy testing mostly requires challenge tests to define onset, level and duration of immunity. Serological test systems to replace the challenges are rarely implemented. The example of efficacy testing of infectious bursal disease vaccines demonstrates the possible replacement of a challenge by a serological test system. Parameters are morbidity, mortality, histological findings, bursa/body-ratios, and humoral antibodies detected by serum neutralization and ELISA.

Animal Welfare↗

PubMed2000

Accurate diagnosis of Helicobacter pylori infection by stool antigen test and 6 other currently available tests in children.

Invasive and noninvasive tests have been developed for the diagnosis of Helicobacter pylori infection. Because H pylori infection is acquired in childhood and adolescence, accurate diagnosis of the infection in the pediatric population is important. We conducted a study to compare invasive tests: culture, biopsy urease test, histology, and polymerase chain reaction on gastric biopsy specimens, with noninvasive tests: serology, (13)C-urea breath test, and a new diagnostic modality, stool antigen test to diagnose H pylori infection. A total of 53 children with symptoms were enrolled in this study, and all had completed the 7 diagnostic tests for H pylori. All the diagnostic tests except serology were excellent methods of diagnosing H pylori infection in children; the diagnostic accuracy was as follows: stool antigen test 96.2%, biopsy urease test 96.2%, histology 98.1%, polymerase chain reaction 94.3%, culture 98.1%, (13)C-urea breath test 100%, and serology 84.9%. The stool antigen test, being highly sensitive and specific, will be potentially very helpful in diagnosing H pylori infection in children.

Adolescent↗

PubMed2002

Test-retest reliability of 4 single-leg horizontal hop tests.

The purpose of this study was to determine the test-retest reliability of 4 single-leg horizontal hop tests (i.e., single hop for distance, triple hop for distance, crossover hop for distance, and 6-m hop for time), with a time interval of approximately 4 weeks separating the 2 testing sessions. Eighteen healthy, young, adult men, all cadets enrolled at the U.S. Air Force Academy, Colorado, performed the single hop for distance, the triple hop for distance, the crossover hop for distance, and the 6-m hop for time during 2 testing sessions separated by 31.2 +/- 0.4 days. Reliability data for each of the single-leg hop tests were studied through a repeated measures analysis of variance, intraclass correlation coefficients (ICCs), and standard errors of measurement (SEMs). The ICCs ranged from 0.92 to 0.97 for the 4 single-leg hop tests. The SEMs for the single-leg hop tests that assessed the distance hopped ranged from 4.61 to 17.74 cm. The SEM for the 6-m hop for time test was 0.06 seconds. No significant differences were noted when the mean scores of the 2 test trials were compared by a repeated measures analysis of variance for any of the single-leg hop tests. These results indicate that the single-leg hop tests examined in this study offer strength and conditioning professionals a reliable method to assess the single-leg horizontal hopping capabilities of healthy, young, adult men, with intervals of approximately 4 weeks between testing sessions.

Adult↗

PubMed1992

[Speech development test for one-year-old infants: I. Test content].

A new speech development test was prepared for one-year-old infants. The test consists of three parts: test I, II, and III. The overall test originally comprised a total of 98 test items (47 for Test I, 32 for Test II and 19 for Test III). Test I (for pre-speech language) Section 1 Situation of language i) Differentiation of information to be communicated ii) Comprehension of speech-related situation (Initiation of "signe", and comprehension of objects and events by means of speech) Section 2 Development of symbolizing function (Development and transformation of ability to handle and manipulate objects) section 3 Representing the function of language (First utterance, and acquisition of meaningful words after first utterance) Test II (for speech comprehension) Ability to name concrete objects, and to relate objects to their uses and functions; comprehension of words representing spatial concept such as quantity, number and dimensions, as well as words representing color or position. Test III (for speech expression) Ability to verbalize or name concrete objects, and to verbalize the conduct and state of a person. For infants, language is an objective to be achieved, while for adults it is the mean of thinking and communicating. Despite this difference the scope of this test comprises two major aspects common to the language-related experience of infants and of adults: pragmatics and vocabulary.

Age Factors↗

PubMed1986

Use of the single radial immunodiffusion test as a replacement for the NIH mouse potency test for rabies vaccine.

The method currently recommended by the World Health Organization (WHO) for the potency assay of rabies vaccine is the NIH mouse potency test, a highly variable test requiring large numbers of animals. The Single Radial Immunodiffusion (SRID) test, an in vitro test, has been used successfully for the quantitation of hemagglutinin in inactivated influenza vaccine and is being evaluated for its utility as an assay for the rabies virus glycoprotein, considered to be the major protective antigen, of rabies vaccine. Potency values calculated using the SRID test were compared with those calculated using the NIH test for rabies vaccines produced in cell culture. The within-test variability was significantly lower with the SRID test but the potency values were generally higher than those from the NIH test. Vaccines which assay below the minimum acceptable potency value (2.5 International Units/ml) in the NIH test generally gave values above that level in the SRID test. The implications of these results on rabies vaccine control testing are discussed.

Animal Testing Alternatives↗

PubMed1988

Human immunodeficiency virus test evaluation, performance, and use. Proposals to make good tests better.

Human immunodeficiency virus (HIV) tests are essential for detecting asymptomatic infection and are helpful in confirming the diagnoses of acquired immunodeficiency syndrome-related complex and acquired immunodeficiency syndrome. Nonetheless, many aspects of their use remain controversial, partly because of concerns about test accuracy. This article reviews the scientific basis for the evaluation, performance, and use of the most commonly employed HIV assays. Current test performance could be improved by better standardization of test procedures and institution of mandatory proficiency testing and licensure of clinical laboratories that perform HIV testing. Test utility could be enhanced by sequencing tests more appropriately and by interpreting test results in conjunction with the clinical purpose for which the test is being used and the characteristics of the population under study. Finally, HIV tests should be evaluated in a manner that minimizes spectrum and referral bias and inadequate reference standard confirmation, problems that have affected the evaluation of current tests.

Acquired Immunodeficiency Syndrome↗

PubMed1994

[Combination of transesophageal atrial pacing and echo-dipyridamole test in the diagnosis of coronary disease in patients with suspected angina pectoris and negative exercise test].

BACKGROUND: Echo-dipyridamole test is an useful tool for non-invasive demonstration of inducible myocardial ischemia in patients with coronary artery disease, its sensitivity being consistently higher as compared with classic exercise stress testing. However, in patients with single vessel who often perform a normal or borderline stress test, even the sensibility of echo-dipyridamole test is comparatively reduced. METHODS: In 19 patients with clinically suspected angina (effort-related in 4, at rest in 8, mixed in 7) and normal exercise stress test, standard echo-dipyridamole test was performed. Thereafter, rapid atrial pacing, a procedure associated with a sharp increase of myocardial oxygen consumption, was performed by means of a transoesophageal catheter during the proceeding 5 min and during 4 min of repeated dipyridamole 0.56 mg/kg infusion. RESULTS: Standard echo-dipyridamole test induced ventricular wall motion abnormalities in 3 patients (one with borderline exercise stress test), whereas repeated pacing-sensitized procedure obtained wall motion abnormalities (apical, septal and lateral) in the same and in 4 additional patients. Coronary angiography demonstrated > 70% stenosis in 8/19 patients (single vessel disease in 5), 7 of whom had been correctly recognized by pacing-dipyridamole test; therefore, sensitivity of the latter as compared with standard dipyridamole test was 87% and 37% respectively. The anatomic correlation of induced wall motion abnormalities with coronary arterial stenosis was demonstrated in all cases. Specificity was 100% with both methods. CONCLUSIONS: Although limited by its restricted patient population, this study suggests that atrial pacing, performed via transoesophageal catheter, can significantly improve the positive predictive value of echo-dipyridamole test in coronary artery disease. By means of this simple procedure, the possibility of non invasively diagnosing even single vessel stenosis in patients with inconclusive exercise stress testing can be significantly improved.

Adult↗

PubMedDate not supplied

[Use of psychopathometric procedures in diagnosis of dementia exemplified by a comparison between the Mini-Mental State and the MWT/KAI (Multiple-Choice Vocabulary/General Intelligence Test Short-Form) test system].

Different definitions of dementia have resulted in various psychopathometric diagnostic instruments. For that reason, the validity of the test or test battery is related to the originating definition of dementia. There are short tests which can be easily handled (e.g., Mini-Mental State or the test battery Multiple-Choice-Vocabulary-Intelligence Test/Short Test for General Intelligence). These tests can be used for the verification of a severe intellectual and mnemonic deterioration or a relative decrease of the mental capacity. For their objectivity, reliability and validity they are suitable for diagnostic routine. However, two aspects should be taken into consideration: Before using psychopathometric tests which aim at objectifying a decrease of mental capacity and indicating the degree of severity, it is necessary to make a differential diagnosis for particularly excluding so-called pseudodementia. It is also a fact that a single test is not sufficient for registering each degree of severity. The Mini-Mental State test can be used for documenting moderate to severe cases of dementia. The test battery Multiple-Choice-Vocabulary-Intelligence Test (MWT)/Short Test for General Intelligence (KAI) is suitable for the diagnosis and follow-up of mild to moderate cases.

Aged↗

PubMed1996

Diagnostic tests for Helicobacter pylori: a prospective evaluation of their accuracy, without selecting a single test as the gold standard.

OBJECTIVE: To assess the accuracy of six commonly used diagnostic tests for Helicobacter pylori in a prospective study without using any specific test as the gold standard (the patient was regarded as H. pylori-infected if two or more tests, whatever their nature, were positive). METHODS: In 105 outpatients undergoing upper GI endoscopy, 62 without significant abnormalities, 28 with gastroesophageal reflux disease, 19 with peptic ulcer, one with erosive gastritis, and one with atrophic gastritis (some patients had more than one diagnosis), antral biopsy specimens were taken for culture, polymerase chain reaction, histological examination (hematoxylineosin and Giemsa stains), and rapid urease test. Corpus biopsy specimens were taken for histological examination. Serology (ELISA) and a 13C-urea breath test were also performed. Consistency of diagnosis between two pathologists was assessed by kappa statistics. RESULTS: Sensitivity and specificity, respectively, were as follows: culture, 98.4 and 100%; polymerase chain reaction, 96.7 and 100%; histological examination (antrum), 96 and 98.8%; histological examination (antrum + corpus), 98.4 and 98.8%; rapid urease test, 90.2 and 100%; 13C-urea breath test, 100 and 100%; and serological examination, 98.4 and 88.4% (95% in those who had not been previously treated for H. pylori). All H. pylori-positive cases were detected by culture and rapid urease test. In 86.4% of these cases all antral biopsy-based tests were positive. Agreement between pathologists was good, with a kappa coefficient around 0.90 for antral biopsy specimens. CONCLUSIONS: All antral biopsy-based tests, as well as the 13C-urea breath test, are accurate for the diagnosis of H. pylori infection. Sampling error is a problem of minor importance. The lower specificity of serological tests may be largely explained by previous treatment of H. pylori.

Biopsy↗

PubMed1997

The 48-Pictures Test: a two-alternative forced-choice recognition test for the detection of malingering.

We tested the validity of the 48-Pictures Test, a 2-alternative forced-choice recognition test, in detecting exaggerated memory impairments. This test maximizes subjective difficulty, through a large number of stimuli and shows minimal objective difficulty. We compared 17 suspected malingerers to 39 patients with memory impairments (6 amnesic, 15 frontal lobe dysfunctions, 18 other etiologies), and 17 normal adults instructed to simulate malingering on three memory tests: the 48-Pictures Test, the Rey Auditory Verbal Learning Test (RAVLT), and the Rey Complex Figure Test (RCFT). On the 48-Pictures Test, the clinical groups showed good recognition performance (amnesics: 85%; frontal dysfunction: 94%; other memory impairments: 97%), whereas the two simulator groups showed a poor performance (suspected malingerers: 62% correct; volunteer simulators 68% correct). The two other tests did not show a high degree of discrimination between the clinical groups and the simulator groups, except in 2 measures: the 2 simulator groups tended to show a performance decrement from the last recall trial to immediate recognition of the RAVLT and also performed better than the clinical groups on the immediate recall of the RCFT. A discriminant analysis with the latter 2 measures and the 48-Pictures Test correctly classified 96% of the participants. These results suggest that the 48-Pictures Test is a useful tool for the detection of possible simulated memory impairment and that when combined to the RAVLT recall-recognition difference score and to the immediate recall score on the RCFT can provide strong evidence of exaggerated memory impairment.

Adult↗

PubMed2005

In vitro skin irritation testing on reconstituted human epidermis: reproducibility for 50 chemicals tested with two protocols.

Since it is of high importance to establish the skin irritation potential of industrial chemicals, toxicologists developed tests on various skin models. Most test data come from the rabbit Draize test, but its reproducibility is questionable. Some human in vivo test data exist, but they concern only few compounds. The emergence of new tools such as reconstituted human skin tissues offers a promising future to alternative methods. We describe here two in vitro skin irritation test protocols performed on reconstituted human epidermis. One is a direct topical application test and the other an in vitro patch test. Both protocols were performed using multiple endpoint analysis including cell viability (MTT reduction), histology, and IL-1alpha release. Fifty chemicals were tested: 20 compounds were used in the ECVAM pre-validation study and 30 products were previously tested in a human in vivo patch test. These in vitro skin irritation tests have not only the advantages of enhanced convenience and of reduced costs, but a good reproducibility is observed by endpoint, and by compound. A prediction model is proposed to classify the chemicals as irritant or non-irritant, and the results are compared to available rabbit and human data. We do not wish to overgeneralize from these 50 compounds; but, instead suggest that this data set be extensively extended to include chemicals of varying physico-chemical properties.

Animal Testing Alternatives↗

PubMed1972

Comparison of a newly developed latex agglutination test and an immunodiffusion test in the diagnosis of systemic candidiasis.

A newly developed latex agglutination (LA) test and a modified immunodiffusion (ID) test were evaluated. The antigen used was a homogenate of Candida albicans. A total of 167 antisera were employed in the evaluation. They included 36 sera from clinically well persons; 78 from patients with various clinical forms of candidiasis; 52 from patients with proven cases of aspergillosis, blastomycosis, coccidioidomycosis, cryptococcosis, histoplasmosis, nocardiosis, paracoccidioidomycosis, sporotrichosis, and tuberculosis; and one serum from a patient with toruloposis. Use of the LA test in conjunction with the ID test permitted the detection of more than 90% of 43 proven candidiasis cases. Of all the heterologous cases and normal human sera tested, LA reactions were noted with 3 of 10 cryptococcosis case specimens, 1 of 9 tuberculosis case specimens, and with the torulopsemia case serum. In contrast, the only heterologous serum reactive in the ID test was that from the patient with torulopsemia. Torulopsis glabrata and C. albicans antisera gave identical reactions in LA and ID tests with T. glabrata or C. albicans antigens. ID tests with selected antigens, however, permitted differentiation of rabbit and human T. glabrata antibody from that of C. albicans antibody. Six different precipitins were recognized with the C. albicans antigens. The occurrence of multiple precipitin lines and high LA titers was suggestive of severe candidiasis. The LA test, in contrast to the ID test, appeared to have prognostic value. Together, the LA and ID tests provided a simple, rapid, and accurate means of detecting and monitoring infections by species of Candida.

Agglutination Tests↗

PubMed1998

Assessing screening tests: extensions of McNemar's test.

We address the problem of comparing a new screening test to a currently available screening test in the absence of a gold standard. When both tests are given to each participant in a clinical trial, the usual analytical approach is to apply McNemar's test for equality of the off-diagonal probabilities, with rejection of the null hypothesis implying that the tests differ. For assessing equivalence, however, we consider a compound null hypothesis that the new test gives either fewer or more positive results than the standard. If both parts of this hypothesis are rejected, we assert equivalence in the rate of positive responses. We propose an extension of McNemar's test for this situation. A companion step is to construct a confidence interval for the ratio of the marginal probabilities and assert equivalence if the interval is sufficiently small. It is also important that the tests agree a large proportion of the time. This can be verified with a complementary two-tailed binomial test. Another situation arises when there is a gold standard for disease diagnosis, and we wish to compare the sensitivity and specificity of two screening tests. We show that a 2 degrees-of-freedom chi-square test based on two McNemar-like tables is an appropriate test.

Chi-Square Distribution↗

PubMed2003

Exact unconditional tests for testing non-inferiority in matched-pairs design.

The problem of testing non-inferiority in a 2 x 2 matched-pairs sample is considered. Two exact unconditional tests based on the standard and the confidence interval p-values are proposed. Although tests of non-inferiority have two nuisance parameters under the null hypothesis, the exact tests are defined by reducing the dimension of nuisance parameter space from two to one using the monotonicity of the distribution. The exact sizes and powers of these tests and the existing asymptotic test are considered. The exact tests are found to be accurate in view of their size property. In addition, the exact test based on the confidence interval p-value is more powerful than the other exact test. It is shown that the asymptotic test is inaccurate, that is, its size exceeds the claimed nominal level alpha. Therefore, it recommends a cautious approach in use of the asymptotic test for the problem of testing non-inferiority, particularly when sample sizes are small or moderately large.

Algorithms↗

PubMed1985

Fetal acoustic stimulation testing: a retrospective experience with the fetal acoustic stimulation test.

The nonstress test is of accepted value in the surveillance of high-risk pregnancies. In order to improve the efficiency of testing, the authors retrospectively evaluated the adjunctive use of acoustic stimulation testing (FAS-TEST) in 1241 patients who underwent 3464 antepartum fetal heart rate tests. The results were compared to those in the previous 6 months during which time 1307 patients underwent 3573 nonstress tests. The frequency of nonreactive tests was 12.6% in the nonstress test group and 6.1% in those patients who underwent the FAS-TEST. The antepartum fetal death rates were not significantly different when the two groups were compared. The FAS-TEST decreases the percentage of nonreactive tests in a high-risk population and, as a consequence, may reduce the testing time.

Acoustic Stimulation↗