Calcium absorption in women: relationships to calcium intake, estrogen status, and age

A total of 526 absorption studies, using both the double-isotope and balance-based methods, were performed in 189 middle-aged women in good general health. The study extended over 17 years of observation, with most subjects studied from two to four times at 5 year intervals. Each study was done on the woman's own self-selected calcium intake and was carried out under inpatient, metabolic balance controls. There was a highly significant inverse correlation between calcium intake and absorption fraction, with the best fit provided by an hyperbola in which absorption fraction is approximately inversely proportional to the square root of intake. The range of absorptive performance was very broad at all intake levels. Mean absorption fraction declined from a value of 0.45 at very low intakes (approximately 200 mg Ca per day) to approximately 0.15 at intakes above 2000 mg/day. There was a highly significant fall in absorption efficiency with age, amounting to approximately 0.0021 per year and a one-time decrease, amounting to approximately 0.022 at the time of menopausal estrogen loss.     

Determination of bone mineral density of the hip and spine in human pedigrees by genetic and life-style factors

In 40 human pedigrees with 563 subjects, we evaluated the contribution of genetic and life-style factors (exercise, smoking, and alcohol consumption) and the interactions between non-genetic factors in determining bone mineral density (BMD) of the hip and spine. In our analysis, we adjusted for age, weight, height, menopausal status in females, life-style factors, and the significant interactions among these factors. For the spine and hip BMD, heritabilities (h(2)) (+/- SE) were, respectively, 0.68 (0.21) and 0.86 (0.28) in males and 0.64 (0.13) and 0.67 (0.14) in females. Exercise had significant beneficial effects for male spine BMD and female hip BMD. Alcohol consumption experienced in our sample had significant beneficial effects on hip BMD in both sexes. Although the main effect of smoking was not significant, there were significant interaction effects between smoking and other important factors (e.g., exercise, weight, alcohol consumption). For example, for female spine BMD, exercise had significant beneficial effects in smokers; however, its effect in non-smokers was non-significant. This result indicates that exercise may reduce deleterious effects of smoking (if any) on BMD, but may have minor effects in increasing BMD in non-smokers. The various interaction effects among risk factors explicitly revealed here for the first time indicate that the detailed effects and direction of individual risk factors may depend on the presence and magnitude of other factors. Weight invariably affected BMD of the hip and spine in both sexes. Age effects were significant for hip BMD, but not for male spine BMD.     

Validation of infant behavior identified by neonatal nurses

Nurses observe that the behavior of an occasional full-term healthy newborn is "unusual," "different," "funny," or "not like the others." This study was designed to determine whether infants identified by nurses as suspect behaved differently from those identified as normal. Suspect infants scored significantly lower on the Brazelton Neonatal Behavior Assessment Scale than their matched controls. No dysfunction was common across the entire suspect group. Although nurses accurately predicted suspect infant behavior, they did not identify the specific Brazelton dimensions on which infants demonstrated worrisome behavior. The results indicated that nurses are reliable sources of information about infant behavior and can be valuable aids in screening infants in need of further assessment. In addition, the data provided tentative insight into the methods nurses use to make clinical judgments. Finally, the results pointed to the possible limitations of the medical model of infant assessment and demonstrated that nurses' empirical knowledge is amenable to measurement and testing. Additional research is necessary to determine if and under what circumstances infants who behave suspiciously are at risk.     

Expediting Transition to Home Parenteral Nutrition With Fast‐Track Cycling

Background. Delivery of home parenteral nutrition (PN) is typically cycled over 12 hours. Discharge to home on PN is often delayed due to potential adverse events (AEs) associated with cycling PN. The purpose was to determine whether patients requiring long‐term PN can be cycled from 24 hours to 12 hours in 1 day instead of 2 days without increasing the risk of PN‐related AEs. Methods. Hospitalized patients receiving PN at goal calories infused over 24 hours without severe electrolyte or blood glucose abnormalities were eligible. Patients were randomly assigned to a 1‐step “fast‐track” protocol or 2‐step “standard” protocol. AEs were defined as hypoglycemia or hyperglycemia, new‐onset or worsening dyspnea, tachycardia, tachypnea, lower extremity or sacral edema, pulmonary edema, or abdominal ascites and were graded as minor or major. Results. In the 63 patients studied, the most prevalent PN‐related AE was hyperglycemia, occurring in 24.2% and 30.0% of patients in the fast‐track and standard groups, respectively. Overall, there was no significant difference in the prevalence of PN‐related minor AEs between fast‐track and standard groups (33.3% and 53.3%, P = .5). No major PN‐related AEs occurred in the fast‐track group, while 1 major PN‐related AE (pulmonary edema) occurred in the standard group. Conclusions. Fast‐track cycling is as safe as standard cycling in patients without diabetes mellitus or major organ dysfunction requiring long‐term PN. Fast‐track cycling could potentially expedite hospital discharge, resulting in decreased healthcare costs and improved patient satisfaction.