Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.

Abstract: Calcium absorption in spontaneously hypertensive rats (SHR) has been reported to be increased, decreased or not different from their normotensive Wistar Kyoto (WKy) control. One postulated reason for these conflicting results is an abnormal sensitivity to the intestinal effects of 1,25(OH)2D3 (1,25D3). Previous studies in everted duodenal sacs and perfused duodenum examined the acute response to 1,25D3 only in 12-week-old SHR, which however already had higher basal rates of calcium absorption. Inability to stimulate Ca absorption further was an unexcluded possibility. To test this hypothesis more vigorously, balance and in situ duodenal 45Ca uptake studies were performed in SHR and WKy using four separate protocols yielding the following results. First, in response to pharmacological doses of 1,25D3 (25 ng/100 g body wt/day X 3), four-week-old normotensive female SHR had higher net calcium absorption (41.4 vs. 31.1 mg/day; 61.6 vs. 48.1%), similar to the increases seen in the untreated state. These results suggest intrinsic epithelial differences independent of 1,25D3. Ca absorption was similarly higher in 1,25D3 treated male SHR (42.9 vs. 36.7 mg/day; 60.1 vs. 53.7%). Second, at 12 to 14 weeks of age, low doses of 1,25D3 (8 ng/100 g body wt/day X 6) stimulated net Ca absorption in the female SHR (33.0 to 39.1 mg/day), but not in WKy (26.8 to 29.3 mg/day). In the male, positive effects were again seen only in the SHR (25 to 45 mg/day). Third, in response to three weeks of dietary Ca deprivation, in situ duodenal 45Ca uptake, measured in the conscious awake state, was higher in 35-week-old SHR (70.9 vs. 53.0%).(ABSTRACT TRUNCATED AT 250 WORDS)
Aging

Abstract: Seventy-six white and black low-income families were interviewed weekly during 1 month to determine how much they spent on food using Food Stamps, WIC coupons, and cash and how much additional food they obtained from different food and meals programs. After families had received their public assistance and Food Stamp allotments for the month, a 24-hour recall was obtained each week from each family member so that food intake could be monitored from the recalls as food-buying resources were depleted. Although families bought most of their food the first 2 weeks, they maintained a relatively constant food intake through the last week of the month. However, when nutrient intakes were compared with Recommended Dietary Allowances, the diets were found to be well supplied in protein, ascorbic acid, thiamin, niacin, riboflavin, vitamin B-12, vitamin A, and phosphorus, and inadequately supplied in vitamin B-6, vitamin D, vitamin E, iron, calcium, magnesium, zinc, and pantothenic acid. Since that finding was true not just at the end of the month but from the beginning, it indicated that the nutrition problems of low-income families are not intermittent, but continuous.
Adolescence

Abstract: Human growth hormone (hGH) levels were measured during rest, prolonged treadmill exercise at 60% maximum O2 uptake (VO2max), and immediate recovery in four groups of subjects (n = 7/group), ages 21-30 yr, classified as male runners (MR), female runners (FR), male controls (MC), and female controls (FC) to determine whether sex differences in the hGH response are related to resting 17 beta-estradiol (E2) and/or cardiorespiratory endurance (CRE). Glucose (Glc), E2, and hGH levels were determined from serial blood samples taken from an intravenous catheter. Glc did not change significantly during exercise, but different trends for the runners (increases) vs. controls (decreases) resulted in higher (P less than 0.01) postexercise levels in the runners. Resting hGH was higher (P less than 0.05) in the FRs and FCs than the MRs and MCs, respectively, and continued to be higher in the FCs (vs. MCs) during the first 30 min of exercise. The MRs achieved higher peak hGH levels and exhibited higher values than the MCs throughout exercise and recovery. There were no statistically significant training differences in the females. The strongest predictors for peak hGH were absolute work load and group (runners vs. controls), both of which combined accounted for 32-36% of the variability (P less than 0.01) in hGH response. Significant sex-related variables (sex, resting E2) accounted for 11-19% of the variability in peak or percent change in hGH, with E2 having a positive effect at rest but a negative effect during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult