Cognitive strategies for reporting portion sizes using dietary recall procedures.

OBJECTIVES: To examine recall strategies used by interview respondents when making judgments about portion size and to better understand how respondents use various portion-size aids. DESIGN: Study participants were separated into groups, each using a different set of portion-size estimation aids: (a) 2-dimensional paper aids presented in stacks, (b) 2-dimensional aids, cut out and presented on rings, (c) household-type aids, and (d) a combination of 2- and 3-dimensional aids, many of which are used in national government surveys. Respondents gave a "quick list" of foods consumed the previous day and practiced cognitive thinking skills. Then the interviewer selected at least 2 solid, 2 liquid, and 2 amorphous foods for probing. Respondents were asked to think aloud as they reported how much they ate of each food. Types and frequencies of cognitive strategies used for portion-size estimation were determined. SUBJECTS: Interviews of 1 to 1 1/2 hours were conducted with 76 adults aged 18 to 65 years. Participants were recruited to obtain a mix of races, ages, educational levels, and genders. RESULTS: The most frequently used strategy was visualization and comparison to aids. Others strategies were known amounts, estimations based on known amounts, visualization of volume or a container, and actions such as pouring or moving hands to the mouth. Respondents preferred aids that were similar in size and shape to actual portions consumed for liquid or amorphous food and preferred the ruler for solid foods. APPLICATIONS: To obtain the best data from dietary recalls, expect answers that are possible for respondents to give, supply respondents with aids that help them recall amounts consumed, and guide respondents to appropriate aids that help them formulate focused responses.

The lack of transplacental movement of the cyanide antidote thiosulfate in gravid ewes.

UNLABELLED: A previous study reported that the co-infusion of IV sodium thiosulfate (STS) with sodium nitroprusside (SNP) to near-term gravid ewes prevented both maternal and fetal cyanide toxicity. We questioned whether maternally administered STS crossed the ovine placenta to enhance fetal transulfuration of cyanide, or whether the fetus was dependent on maternal detoxification of cyanide after diffusion of cyanide into the maternal circulation. Ten anesthetized, near-term gravid ewes underwent hysterotomies with delivery of fetal heads for venous catheterization. Five control ewes received IV isotonic sodium chloride solution, whereas five experimental ewes received IV STS (50 mg/kg over 15 min). Serial plasma thiosulfate concentrations in ewes and fetuses were measured over 135 min. Areas under the time-plasma thiosulfate concentration curves were calculated for experimental and control ewes at 2758+/-197 and 508+/-74 min x mg(-1) x L(-1), respectively (P < 0.008). Mean areas under the curve for experimental and control fetuses were 236+/-34 and 265+/-23 min x mg(-1) x L(-1), respectively (P > 0.5). Maternally administered STS may prevent fetal cyanide poisoning from SNP administration without relying on STS crossing the placenta into the fetal circulation. Fetal cyanide may cross down a concentration gradient from fetal to maternal circulation, to be transulfurated to thiocyanate in maternal tissues. IMPLICATIONS: We evaluated the mechanism of action of sodium thiosulfide (STS) in sodium nitroprusside-induced cyanide toxicity in the ewe. Fetal cyanide poisoning is alleviated by maternal administration of STS, although this cyanide antidote apparently does not cross the placenta.