Indeterminate Responses Research Articles

When is a conclusion worth deriving? A relevance-based analysis of indeterminate relational problems

When is a conclusion worth deriving? We claim that a conclusion is worth deriving to the extent that it is relevant in the sense of relevance theory (Sperber & Wilson, 1995). To support this hypothesis, we experiment with “indeterminate relational problems” where we ask participants what, if anything, follows from premises such as A is taller than B, A is taller than C. With such problems, the indeterminate response that nothing follows is common, and we explain why. We distinguish several types of determinate conclusions and show that their rate is a function of their relevance. We argue that by appropriately changing the formulation of the premises, the relevance of determinate conclusions can be increased, and the rate of indeterminate responses thereby reduced. We contrast these relevance-based predictions with predictions based on linguistic congruence.

Acute pulmonary embolism: cost-effectiveness analysis of the effect of artificial neural networks on patient care.

To evaluate the cost-effectiveness of artificial neural networks for diagnosis in patients suspected of having acute pulmonary embolism who are typically referred for pulmonary angiography. Four diagnostic strategies were explored to help define the diagnostic role of neural networks in patients suspected of having pulmonary embolism in whom nondiagnostic ventilation-perfusion lung scans were obtained. First, a network was used to determine which patients could be directly referred for treatment without angiography. Second, the network was applied to determine in which patients treatment could be withheld. Third, the network was used to distinguish patients in whom the network gave indeterminate responses and who should proceed to angiography. Each strategy was compared with use of angiography in terms of morbidity, mortality, and cost per life saved. The use of the neural network reduced the average cost per patient by more than one-half relative to the cost of angiography. Morbidity and mortality rates were also comparable to or lower than those associated with angiography. The results were consistent regardless of the prevalence of disease. The use of neural networks in the diagnosis of pulmonary embolism is a promising way to improve cost-effectiveness in the care of patients with nondiagnostic lung scans.

Prognostic Factors for All-Cause Mortality among Hemophiliacs Infected with Human Immunodeficiency Virus

To identify the prognostic significance of hemophilia- and virus-related factors, the authors undertook a survival analysis among 644 human immunodeficiency virus (HIV)-infected subjects enrolled in the Multicenter Hemophilia Cohort Study between 1985 and 1993. Acquired immunodeficiency syndrome (AIDS) was the leading cause of death, followed by hemorrhage and hepatic disease. Adverse prognostic factors included older age and CD4-positive lymphocyte values below 14 percent either at entry (age-adjusted mortality rate ratio (RR) = 6.4, 95% confidence interval (CI) 3.4-12.1) or after entry (time-dependent RR = 4.2, 95% CI 2.6-6.7); indeterminate antibody responses to hepatitis C virus (RR = 3.0, 95% CI 1.8-5.0); and inhibitory antibodies to factor VIII concentrates (RR = 1.8, 95% CI 1.1-3.1). Indeterminate hepatitis C virus status was associated with mortality from hepatic disease but not with AIDS mortality. Factors that were not prognostic included duration of HIV infection, hepatitis B virus infection, and other hemophilia variables. These findings suggest that fatal liver disease among coinfected subjects with an indeterminate hepatitis C virus status is probably related to an insufficient humoral response secondary to HIV immune dysfunction and that the risk of death among HIV-infected subjects is best evaluated with age and duration of low CD4 percentage.

Maternal factors associated with prenatal transmission of ovine lentivirus.

Prenatal transmission of ovine lentivirus (OvLV) was studied in 85 eyes and their offspring. The animals were from a flock with endemic OvLV infection and 49 (58%) had serum antibodies to OvLV. Blood was collected from all lambs before they nursed. Using the polymerase chain reaction (PCR), OvLV DNA was detected in peripheral blood mononuclear cells of 13 (11%) of 117 lambs, including two sets of twins. Mothers with OvLV-infected lambs (n = 11) were younger (mean, 2.5 years) and had fewer pregnancies (mean, 2.4) than seropositive ewes (3.2 years and 3.2 pregnancies; P < .05). Of mothers with OvLV-positive lambs, 4 had plasma antigenemia (mean, 31.3 +/- 2.1 ng/mL OvLV) in conjunction with indeterminate antiviral antibody responses by immunoblotting. These results suggest that maternal factors (age and parity) and host-virus interactions (antiviral antibody and antigenemia) are important risk factors in prenatal transmission of OvLV.

Western Blotting in the Serodiagnosis of Lyme Disease

There are currently no accepted criteria for positive Western blots in Lyme disease. In a retrospective analysis of 225 case and control subjects, the best discriminatory ability of test criteria was obtained by requiring at least 2 of the 8 most common IgM bands in early disease (18, 21, 28, 37, 41, 45, 58, and 93 kDa) and by requiring at least 5 of the 10 most frequent IgG bands after the first weeks of infection (18, 21, 28, 30, 39, 41, 45, 58, 66, and 93 kDa). When these definitions were tested in a prospective study of all 237 patients seen in a diagnostic Lyme disease clinic during a 1-year period and in 74 patients with erythema migrans or summer flu-like illnesses, the IgM blot in early disease had a sensitivity of 32% and a specificity of 100%; the IgG blot after the first weeks of infection had a sensitivity of 83% and a specificity of 95%. Among patients with indeterminate IgG responses by ELISA, 6 of 9 patients with active Lyme disease had positive blots compared with 2 of 34 patients with other illnesses (P < .001). Thus, Western blotting can be used to increase the specificity of serologic testing in Lyme disease.

Premature pubarche: etiological heterogeneity.

Premature pubarche is characterized by pubic hair, adult type body odor, acne, and axillary hair before 8 yr of age in girls and 9.5 yr of age in boys. Causes of this premature virilization include premature adrenarche, mild errors of steroidogenesis, precocious puberty, and adrenal and gonadal tumors. To determine whether any clinical parameters are helpful in distinguishing which children should undergo further evaluation for mild congenital adrenal hyperplasia, we performed ACTH stimulation tests in 69 children with premature pubarche and 8 pubertal controls. Patients were categorized as having typical (pubic hair with or without axillary hair and body odor) or atypical (pubic hair and genital enlargement) premature pubarche. Blood samples, before and 30 min after iv bolus administration of synthetic ACTH, were obtained for progesterone, 17-hydroxypregnenolone, 17-hydroxyprogesterone, dehydroepiandrosterone, androstenedione, 11-deoxycortisol, and cortisol measurements. The patients were divided into 4 groups based on their individual responses to ACTH stimulation: premature adrenarche (no apparent defect in steroidogenesis), possible decreased 21-hydroxylase activity, possible decreased 3 beta-hydroxysteroid dehydrogenase activity, and indeterminate responses. Five of 11 (45%) children with atypical premature pubarche and 7 of 58 (12%) children with typical premature pubarche were found to have evidence of mild defects in steroidogenesis. Similar to previous reports in postpubertal women, only responses to ACTH stimulation allowed accurate classification of these patients.

Indeterminate and Determinate Soybean Responses to Planting Date1

AbstractDeterminate and indeterminate soybean [Glycine max (L.) Merr.] strains respond differently to planting date in the northern United States. The objectives of this study were to compare performance of closely related determinate and indeterminate strains in response to planting date. Five pairs of determinate and indeterminate isolines or related cultivars were evaluated at three planting dates for 1 yr, and five planting dates for two succeeding years at West Lafayette, IN. Dates were recorded when plants reached stages V1 to V5 and all reproductive stages. Additional data were recorded on agronomic characteristics of the isolines. Planting delays resulted in fewer days between stages V1 to V5 in 2 of the 3 yr and in stages R2 through R8 in all 3 yr. Determinate and indeterminate strains responded the same to planting delays in the vegetative stages V1 to V5 but not in the reproductive stages. Indeterminate strains were shorter and had fewer nodes with planting dates after May 24. Determinate strains either increased or were the same in plant height and number of nodes with successive planting dates after May 24. When lodging was moderate to severe, strains of both types lodged more severely when planted in June than in May. In general, determinate strains yielded more when planted late May or early June; indeterminate strains produced maximum yields when planted from early to late May. Determinate strains responded similarly to planting date regardless of the source of the dt1 gene.

Comparison of epidemiologic data from multiple sources

We compared epidemiologic data collected from medical records and by interview for 462 subjects who were part of a case-control study of a chronic disease (cancer of the breast). The collected data included such clinical and pharmaceutical features as history of lactation, hysterectomy, diabetes mellitus, type of menopause, and whether a woman had used exogenous estrogens. We found that agreements between medical record and interview data are variable, and depend on the type of data examined and the strategy for handling incomplete or ambiguous (indeterminate) responses. For variables that represent inherent features of the patients' clinical condition, such as gynecologic surgical procedures and a family history of breast cancer, we found excellent agreement between the medical record and interview. For pharmaceutical features, however, we discovered considerable variability between the two data sources. We also detected substantial problems with a common tactic in which information from individual data sources are pooled to form a new “combined data source”. In this analysis, combining data sources creates estimates for the proportion exposed that are different from estimates in either of the original information sources.

Growth responses of Neisseria gonorrhoeae auxotypes to required amino acids and bases in liquid medium

Neisseria gonorrhoeae strains can be grouped or differentiated (auxotyped) by their requirements for none, or any one or more of proline, uracil, hypoxanthine, and citrulline or ornithine. Most strains were readily assessed because they responded with growth or no growth on each defined auxanographic medium. Other strains gave indeterminate responses on agar and the reasons were not obvious. Liquid growth studies for quantifying the usual responses showed that yields of appropriate N. gonorrhoeae auxotrophs were proportional to replacement concentrations of any one of these amino acids or bases, of methionine, or of cysteine plus cystine. This type of response, where log growth rates and lag times were unaffected, is proposed as the basis for defining (simple) auxotrophy in gonococci. The formula of the defined medium was improved by increasing proline, uracil, and hypoxanthine beyond limiting concentrations, and decreasing citrulline or ornithine, and cysteine plus cystine. Fatty acid--free bovine albumin was used to ensure homogeneous growth in liquid media. In agar, it was superior to starch for the nonnutritive protective effect required by many strains.