An investigation of dentists' and dental students' estimates of diagnostic probabilities.

BACKGROUND: Research in medicine has shown that physicians have difficulty estimating the probability that a patient has a condition on the basis of available diagnostic evidence. They consistently undervalue baseline information about the patient relative to test information and are poor intuitive calculators of probability. The authors could not locate in the literature any studies of diagnostic probability estimates from baseline information and test data for dentists. METHODS: Using two vignettes that contained different baseline information, dental students and clinical faculty members estimated the probability that the described hypothetical patient had the condition in question. Respondents also commented on the project. CONCLUSIONS: Both groups of respondents overemphasized the importance of test evidence relative to baseline information, although experienced practitioners did so to a lesser extent than did students. Respondents, especially practitioners, expressed resistance to performing a diagnostic task that required precise estimates of probability. CLINICAL IMPLICATIONS: Dentists appear to estimate diagnostic probabilities in an intuitive fashion, but they do so imprecisely. Clinical experience provides some protection against the bias of overestimating test evidence compared with baseline information. These findings raise questions about how practitioners use probability estimates and whether other models also may play a role. The incorporation of information from evidence-based dentistry into practice requires better understanding.

Crystal structures of vegetative soybean lipoxygenase VLX-B and VLX-D, and comparisons with seed isoforms LOX-1 and LOX-3.

The lipoxygenase family of lipid-peroxidizing, nonheme iron dioxygenases form products that are precursors for diverse physiological processes in both plants and animals. In soybean (Glycine max), five vegetative isoforms, VLX-A, VLX-B, VLX-C, VLX-D, VLX-E, and four seed isoforms LOX-1, LOX-2, LOX-3a, LOX-3b have been identified. In this study, we determined the crystal structures of the substrate-free forms of two major vegetative isoforms, with distinct enzymatic characteristics, VLX-B and VLX-D. Their structures are similar to the two seed isoforms, LOX-1 and LOX-3, having two domains with similar secondary structural elements: a beta-barrel N-terminal domain containing highly flexible loops and an alpha-helix-rich C-terminal catalytic domain. Detailed comparison of the structures of these two vegetative isoforms with the structures of LOX-1 and LOX-3 reveals important differences that help explain distinct aspects of the activity and positional specificity of these enzymes. In particular, the shape of the three branches of the internal subcavity, corresponding to substrate-binding and O(2) access, differs among the isoforms in a manner that reflects the differences in positional specificities.