Biomedical subjects
B K Snyder
Publications and source records attributed to B K Snyder.
Effect of magnesium hydroxide administration on iron absorption after a supratherapeutic dose of ferrous sulfate in human volunteers: a randomized controlled trial.
STUDY OBJECTIVE: Animal models have demonstrated that administration of magnesium hydroxide (MgOH) decreases serum iron levels after an iron overdose. We designed this study to determine the effect of MgOH administration on iron absorption and adverse effects after a supratherapeutic dose of ferrous sulfate in healthy male volunteers. METHODS: We conducted a prospective, unblinded, randomized trial involving 16 healthy, fasting men. All subjects ingested a 10-mg/kg dose of elemental iron in the form of ferrous sulfate. One-half hour after the iron dose, the 8 subjects in the experimental group were given 5 mg of MgOH for every 1 mg of ingested elemental iron. Serum iron levels were obtained at baseline and at each subsequent hour for 6 or 7 hours. Serum magnesium levels were obtained at baseline, after 3 hours, and after 6 hours. Side effects were recorded hourly. Serum iron levels between groups were compared by repeated-measures ANOVA and ANCOVA. The 95% confidence intervals (CIs) for the difference in serum iron levels between groups at each time point and for the difference in peak serum iron level between groups were calculated. RESULTS: Baseline mean serum iron levels did not differ between the 2 groups (P =.28). There were no statistical differences between groups (P =.20). Mean serum iron levels at each time point and peak serum iron levels did not differ significantly between groups. The mean peak serum iron level was 300.8 micrograms/dL in the control group and 272.5 micrograms/dL in the experimental group. CONCLUSION: Administration of MgOH does not affect iron absorption in humans after a supratherapeutic dose of iron when the ratio of MgOH to elemental iron is 5:1.
Accuracy of leukocyte count in the diagnosis of acute appendicitis.
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Stress and psychosocial factors: effects on primary cellular immune response.
Life stress is associated with decreases in some immune functions, but little is known about the effect of stress on immune response to active immunization. We examined the relationships between stressful events, psychosocial, and biologic factors and primary immune response to a novel antigen-keyhold limpet hemocyanin (KLH). Lymphocyte proliferation (LP) was measured prior to immunization and 3 and 8 weeks following KLH immunization. At 3 weeks, LP was significantly lower in subjects reporting more "bad" stress and those experiencing more psychological distress, while "good" stress and social support tended to be associated with higher LP. There was a trend toward the more stressed subjects having lower baseline, but higher 8-week, LP responses. The model that best fits these data suggests that psychosocial processes mediate the relationship between stressful events and primary immune response, while biologic factors, such as recent weight gain, show direct independent effects on immune response.
Effect of stress and other biopsychosocial factors on primary antibody response.
There is growing evidence that life stress is associated with altered cellular immune function, but only a few studies have examined the effect of stress on humoral immune response. We immunized 89 healthy women (18-24 years) with a novel antigen, keyhole limpet hemocyanin (KLH), to study the impact of stressful events and psychosocial and biologic factors on primary antibody response to immunization. Antibodies to KLH were measured preimmunization and 3 and 8 weeks after immunization. Previously validated scales were used to measure (1) recent major stress (both "good" and "bad," as defined by the subjects) and minor stressful events, and (2) psychological status and social support. Subjects were also asked about personal medical history, sociodemographics, and side effects of immunization. Subjects with more stressful events (of any type) tended to have lower baseline and 3-week postimmunization IgG levels. Those reporting more "good" events tended to have higher IgG levels at 8 weeks postimmunization. Psychological Distress scores correlated negatively and Psychological Wellbeing scores correlated positively with each IgG level. Subjects with a recent infection (preimmunization) or a local reaction to immunization had significantly higher IgG levels at all three points compared to those without these factors. These data and exploratory analysis suggest that recent stress and psychological status (perhaps representing the cumulative effects of stress and response to stress) may influence immune response to immunization. However, predisposing biological factors must also be assessed for possible confounding in the stress-immune response relationship.
Low serum complement levels in anorexia nervosa.
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