Interpretation by clinicians of probability expressions in cytology reports and effect on clinical decision-making.

BACKGROUND: Cytology often is used to obtain a diagnosis, such as that of malignant neoplasia. When a diagnosis is uncertain, pathologists often express probability using qualitative terms, such as "probable," that have imprecise meanings. HYPOTHESIS: Terms expressing probability are interpreted variably by veterinary practitioners and affect decisions regarding treatment and euthanasia. ANIMALS: None. METHODS: An online survey of members of the Veterinary Information Network was conducted. Veterinarians were asked to assign percentage probabilities to 18 modifiers of a diagnosis of lymphoma. They also were asked to select their most likely clinical action based on a diagnosis of lymphoma qualified one of 4 modifiers. Results were analyzed using descriptive and nonparametric methods. Percentage probabilities were analyzed by ANOVA after variance stabilization. RESULTS: For 871 valid surveys, probabilities assigned to the 18 modifiers overlapped substantially, with medians (interquartile range) of 50% (50-70%) for "possible," 66% (66-85%) for "probable," and 70% (70-90%) for "consistent with." More (P < .001) veterinarians (50.4%) chose to initiate treatment with a diagnosis of "consistent with lymphoma" as compared with "probable" (14.6%) or "possible" (1.6%) lymphoma. For clients considering euthanasia if the diagnosis was cancer, more (P < .001) veterinarians recommended euthanasia with a diagnosis of "consistent with lymphoma" (62.5%) as compared with "probable" (35.3%), or "possible" (2.0%) lymphoma. CONCLUSIONS AND CLINICAL IMPORTANCE: Probability expressions are interpreted variably yet have a major impact on clinical decision-making, including the decision to recommend euthanasia. Standardized terminology could improve decision-making and enhance clinical outcome.

Dietary Iodine and selenium interact to affect thyroid hormone metabolism of rats.

The interaction of dietary selenium and iodine on the activities of the selenoenzymes, selenium-dependent glutathione peroxidase (GSH-Px), and type I deiodinase (DI-I), and the thyroid hormones thyroxine (T4) and triiodothyronine (T3) were studied. Male weanling Sprague-Dawley rats were fed an AIN-93G diet for 6 wk with modified selenium and iodine concentration as follows: three levels each of iodine and selenium (0.03, 0.2 added and 1.0 added mg iodine/kg diet, and 0.05, 0.18 added and 1.0 added mg selenium/kg diet) were used in a 3 x 3 factorial design. Renal, but not hepatic, DI-I activity was lower in rats with low selenium intake than in controls. Circulating T3 concentration was not affected by the dietary levels of iodine or selenium. Unlike in liver, kidney and erythrocytes, thyroidal GSH-Px activity was not lower than in controls in rats with low selenium intake, but was significantly higher when iodine intake was low. Significant interactions of iodine and selenium on serum T4 and thyroidal GSH-Px activity were observed. Serum T4 was maintained at control levels when both dietary iodine and selenium were low, but not when iodine alone, or selenium alone, was low. Activity of thyroidal GSH-Px was lowest in rats fed a diet containing high iodine and low selenium. The results suggest that high iodine intake, when selenium is deficient, may permit thyroid tissue damage as a result of low thyroidal GSH-Px activity during thyroid stimulation. A moderately low selenium intake normalized circulating T4 concentration in the presence of iodine deficiency.

A method for the determination of type I iodothyronine deiodinase activity in liver and kidney using 125I-labelled reverse triiodothyronine as a substrate.

OBJECTIVES: A detailed method for the determination of iodothyronine deiodinase type 1 (DI-1) activity is described. The objective of the present method development was to consolidate the effective procedures of previous methods and produce an efficient assay that can be easily reproduced. DESIGN AND METHODS: This method uses a 5',-125I labelled rT3 as substrate and ion-exchange chromatography to separate released ionic iodine. Released 125I- collected in the eluate is counted, and the results used to calculate DI-1 activity. RESULTS: Results were found to be linear for tissue homogenates containing 3-11 mg protein.mL-1. Day-to-day coefficient of variation of liver homogenate was determined to be 13%. CONCLUSIONS: This method was found to be reliable, reproducible, and sample sizes as small as 10 microL could be readily assayed. The use of centrifuge filter units to contain the ion-exchange medium decreased handling of the material, and potential sources of error.