Biomedical subjects

Sarah L Booth

Publications and source records attributed to Sarah L Booth.

22 records · Page 2Linked to original sources

PubMed2003

Coronary calcium quantification using various calibration phantoms and scoring thresholds.

RATIONALE AND OBJECTIVES: To compare scoring threshold and calibration method-dependent accuracy and variability of coronary calcium measurements by multidetector computed tomography (MDCT). METHODS: Ninety-five subjects were scanned with MDCT. We calculated Agatston score and volume score. Mineral mass (MM) was calculated using patient-based and scanner-based calibration methods. Accuracy of calibration was validated using artificial calcium cylinders. RESULTS: Patient-based and scanner-based calibration permitted accurate quantification of artificial calcium cylinders (bias: 0 mg and -2 mg). In the subjects, the mean relative difference of MM measurements performed at 90 and 130 Hounsfield units threshold (59%) was lower than for Agatston score (94%) and volume score (109%; P < 0.05). Patient-based and scanner-based calibration yielded systematically different MM measurements (bias: 22%). CONCLUSIONS: MM lowers threshold-dependent variability of coronary calcium measurements. Patient-based and scanner-based calibration allows accurate calcium quantification ex vivo but reveal systematic differences in subjects. Patient-based calibration may better account for subject size and composition.

Aged↗

PubMed2002

Dietary and nondietary determinants of vitamin K biochemical measures in men and women.

Few epidemiological studies that rely on the food frequency questionnaire (FFQ) for dietary assessment have measured biomarkers of vitamin K intake to independently confirm associations between self-reported dietary vitamin K intake and disease risk. Associations were examined between two sensitive biomarkers of vitamin K status, plasma phylloquinone and serum percent undercarboxylated osteocalcin (%ucOC), and self-reported usual phylloquinone intake as estimated from a FFQ. The influence of other dietary and nondietary factors on plasma phylloquinone concentrations was also examined. Dietary phylloquinone intake was estimated using a FFQ in 369 men and 468 women of the Framingham Offspring Study. The prevalence of high %ucOC concentrations (>/= 20%), suggestive of a low vitamin K status, was 44% in men and 54% in women, respectively. After multivariate adjustment, the odds of a high %ucOC was 2.5 greater for women (odds ratio: 2.5; 95% confidence interval [CI]: 1.2-5.1) and almost three times greater for men (odds ratio: 2.8; 95% CI: 1.3-5.9) in the lowest dietary phylloquinone intake quintile category compared to the highest quintile category. Fasting triglyceride concentrations, smoking status and season were associated with plasma phylloquinone concentrations, independent of dietary phylloquinone intake. Phylloquinone and green vegetable intake was linearly associated with plasma phylloquinone, after adjustment for potential confounding factors. There were limitations in the use of the FFQ to predict plasma phylloquinone, evident in an observed plateau effect and required nondietary adjustment factors. Despite these caveats, these findings support the use of a FFQ for a relative assessment of vitamin K status in population-based studies.

Adult↗

PubMed2002

Phylloquinone absorption from phylloquinone-fortified oil is greater than from a vegetable in younger and older men and women.

Studies that have compared the absorption of phylloquinone from green vegetables and oils have equivocal results. To address differences in approaches used to assess absorption of phylloquinone, a 24-h absorption study was conducted in 18 younger (20-40 y) and 18 older (60-80 y) men and women as part of a larger metabolic study that compared changes in vitamin K status in response to broccoli and phylloquinone-fortified oil (377 +/- 46 and 417 +/- 45 micro g/d, respectively). Absorption was defined as the 24-h area under the curve (AUC) for plasma phylloquinone concentrations (both unadjusted and adjusted for triglyceride concentrations). The mean AUC for plasma phylloquinone concentrations (both unadjusted and adjusted) were significantly greater after consumption of the phylloquinone-fortified oil diet compared with the broccoli diet (P < 0.001). However, there were no differences between the two treatments in 24-h fasting plasma phylloquinone concentrations. Although there were no age differences in the AUC for plasma phylloquinone adjusted for triglycerides, older adults had significantly higher plasma phylloquinone concentrations (both unadjusted and adjusted) at 0 and 24 h than the younger adults (P < 0.001). These data emphasize that the use of different approaches for the assessment of vitamin K absorption can result in disparate conclusions.

Absorption↗

PubMed2002

Effects of orlistat on fat-soluble vitamins in obese adolescents.

STUDY OBJECTIVES: To determine whether orlistat causes fat-soluble vitamin deficiencies in African-American and Caucasian adolescents. DESIGN: Prospective, open-label pilot study. SETTING: Warren Grant Magnuson Clinical Center of the National Institutes of Health. PATIENTS: Seventeen adolescents with body mass indexes above the 95th percentile for age, race, and gender who also had at least one obesity-related comorbid condition. INTERVENTION: Subjects received orlistat 120 mg 3 times/day and a daily multivitamin supplement containing vitamin A 5000 IU, vitamin D 400 IU, vitamin E 300 IU, and vitamin K 25 microg. MEASUREMENTS AND MAIN RESULTS: During 3-6 months of orlistat treatment, acute absorption of retinol (vitamin A) was not significantly altered, but absorption of alpha-tocopherol (vitamin E) was significantly reduced compared with baseline levels (p<0.001). Serum levels of vitamins A and E did not change significantly; however, there was a nonsignificant decrease in vitamin K. Mean vitamin D levels were significantly reduced compared with baseline (p<0.02) after 1 month of orlistat, despite multivitamin supplementation. CONCLUSION: It may be prudent to monitor vitamin D concentrations in adolescents who take orlistat, even when a multivitamin is prescribed.

Adolescent↗