Biomedical subjects

Charles C Brown

Publications and source records attributed to Charles C Brown.

2 recordsLinked to original sources

PubMed2003

Relationship between sperm characteristics and hormonal parameters in normal couples.

OBJECTIVE: To examine the relationships between hormone profiles and semen analysis measures and fertility in the male partners of presumed normal couples. DESIGN: Prospective clinical study. SETTINGS: Healthy volunteers in an academic research environment. PATIENT(S): One hundred forty-five reproductive age couples without known risk factors for infertility and who had discontinued contraception to achieve pregnancy completed this component of this study. Each couple was followed for < or =12 menstrual cycles while they attempted to conceive. INTERVENTION(S): Semen quality measures for the first ejaculates were obtained at the start of the study along with a single blood sample. Levels of FSH, bioactive FSH, inhibin B, LH, and T were measured for each man. MAIN OUTCOME MEASURE(S): Semen analysis, FSH, inhibin B, LH, T, and clinical pregnancy. RESULTS: Significant positive relationships were observed between the two measures of FSH as well as between both of the FSH measures and LH. Follicle-stimulating hormone as measured by RIA was significantly negatively correlated with inhibin B. Inhibin B showed a marginally significant negative correlation with LH, and LH and T had a marginally significant positive correlation. Inhibin B increased significantly, and both measures of FSH activity showed significant decreases, with increasing levels in several semen quality measures. There was no significant relationship between the measured hormones and the pregnant and nonpregnant groups or time to pregnancy. CONCLUSION(S): These results contribute additional information on the utility of reproductive hormone measurements for predicting semen quality in couples without known reduced fertility.

Adult↗

PubMed2002

Cognitive research enhances accuracy of food frequency questionnaire reports: results of an experimental validation study.

OBJECTIVE: To test whether changing a food frequency questionnaire (FFQ) on the basis of cognitive theory and testing results in greater accuracy. Accuracy was examined for 4 design issues: a) Grouping: asking about foods in a single vs multiple separate questions; b) different forms of a food: asking consumption frequency of each form of a food (eg, skim, 2%, whole milk) vs a nesting approach--asking frequency of the main food (eg, milk) and proportion of times each form was consumed; c) additions (eg, sugar to coffee): asking independent of the main food vs nested under the main foods; d) units: asking frequency and portion size vs frequency of units (eg, cups of coffee). DESIGN: Participants in two randomly assigned groups completed 30 consecutive daily food reports (DFRs), followed by 1 of 2 FFQs that asked about foods consumed in the past month. One was a new, cognitively-based National Cancer Institute (NCI) Diet History Questionnaire; the other was the 1992 NCI-Block Health Habits and History Questionnaire. SUBJECTS/SETTING: 623 participants, age range 25 to 70 years, from metropolitan Washington, DC. Statistical analyses performed Accuracy was assessed by comparing DFR and FFQ responses using categorical (percent agreement) and continuous (rank order correlation, discrepancy scores) agreement statistics. RESULTS: Grouping: accuracy was greater using separate questions. Different forms of food: accuracy was greater using nesting. Additions: neither approach was consistently superior; accuracy of the addition report was affected by accuracy of the main food report. Units: both approaches were similarly accurate. CONCLUSIONS: Accuracy of FFQ reporting can be improved by restructuring questions based on cognitive theory and testing.

Adult↗