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The role of prenatal vitamin D sufficiency and supplementation in the development of childhood aeroallergen sensitization and allergic rhinitis remains uncertain.

There is an increasing interest in the use of ambulatory blood pressure monitoring in pediatric populations in recent years with many groups now collecting data. It is not known to what extent the data across groups is comparable. Therefore, the purpose of this study was to directly compare the data generated by two different research groups to determine if the results are comparable and to provide a larger sample size to examine the issues of racial and sex differences. One sample consisted of 196 subjects from Augusta, Georgia (81 male (M), 115 female (F), 95 Caucasian (C), 101 African American (AA), aged 8-19, mean age=13.9) (AUG). All of the subjects had a positive family history of either hypertension or myocardial infarction. The second sample consisted of 300 subjects from Memphis, Tennessee (160 M, 140 F, 149 C, 151 AA, aged 10-18, mean age =13.3) (MEM). The majority of these subjects did not have a known family history. Analysis of variance models were run for daytime, nighttime, and daytime minus nighttime systolic blood pressure (SBP) and diastolic blood pressure (DBP). Location was significant for daytime SBP with higher BP in the AUG group (117±8 v 114±10 mmHg; p<0.001). M also had higher daytime SBP (118±10 v 113±8 mmHg; p<0.001) and daytime DBP, again with higher levels in the AUG group (71±7 v 66±6 mmHg; p<0.001). The race by sex interaction was significant for nighttime SBP (p<0.03) with higher SBP for AAM than AAF SBP (112±10 v 106±9 mmHg; p<0.001), but similar levels in C subjects. Location had an effect for nighttime DBP with higher DBP for the AUG group (61±7 v 59±7 mmHg; p<0.002). Location was the only significant effect for the change from daytime to nighttime SBP, with a greater change in the AUG group (10±8 v 8±8 mmHg; p<0.001) and the change in DBP, with a greater change for the AUG group (12±8 v 5±6 mmHg; p<0.001). These greater changes for the AUG group were due to the fact that this group had higher daytime BP, but the groups had comparable nighttime BPs. In conclusion, these two groups had similar patterns, with higher BPs in males than females and higher nighttime BPs in AA compared to C. The primary difference between the groups was in daytime BP. We speculate that this is due to a greater influence of family history of cardiovascular disease on BP responses to the physical and psychological demands of the day because it is not apparent during the nighttime hours when the activity of the sympathetic nervous system is greatly diminished.

We and others have hypothesized that stress induced changes in sodium regulation contributes to the development of salt sensitive hypertension. It is important to normalize the sodium intake in studies that examine this hypothesis to insure that the subjects are at similar levels of sodium balance when they are tested. This is a particular problem in adolescents because of their lifestyles. We have developed a 3-day dietary protocol to control the sodium intake in a study of stress induced changes in sodium handling in African-American youths aged 15 to 18 years. The purpose of this report is to document our success with this dietary plan and describe the factors related to differences in this success. The dietary plan is based on a limited choice diet containing the normal sodium intake of teenagers in our region of the country (4000±200 mg/day) and utilizes pre-packaged foods. A research assistant meets with each subject to select the diet for each day. The selected foods are packed in coolers which the subjects pick up each day. The coolers are then returned the next day with all the wrappers and an overnight urine collection to determine dietary compliance. Of the 64 subjects tested thus far, 60 (93.7%) have complied with the diet as determined by urinary sodium values from the overnight collections. The variability in sodium intake across subjects was significantly reduced from the first day to the third day of the diet (153±67 to 121±53 mmol/L (p<0.03). This resulted in a standard deviation in UNaV of only 6.7 mEq/hr at the beginning of the test period. There were sex differences in the amount of sodium that was consumed based on returned foods and wrappers. Males (n=29) consumed an average of 88.7% of the total sodium they were provided compared to 77.7% for the females (n=31). Further analysis showed that within the females these differences were significantly correlated with body weight (r=.48; p< .007). There was not a significant relationship in the males. However, these sex differences did not result in sex differences in baseline UNaV during the testing procedure (21±12 v 19±11 mEq/hr). In conclusion, we have developed a dietary protocol that we believe is effective in normalizing the dietary intake of sodium in adolescents. This protocol can be used in any study in which it is important to bring adolescents into comparable levels of sodium balance.