Calcium and vitamin D status in the adolescent: key roles for bone, body weight, glucose tolerance, and estrogen biosynthesis.

This review paper highlights a number of important public health issues related to calcium and vitamin D status in adolescents. Dietary calcium intake has declined dramatically over the past several decades among adolescents, and inadequate serum vitamin D levels have been documented in up to 54% of teens. A recent trend of decreasing consumption of dairy foods, especially milk, has contributed to this problem. Calcium and vitamin D are critically important for bone mineral accrual during adolescence, and altered calcium homeostasis can impact optimal bone acquisition. Serum and cellular calcium concentrations are controlled, in part, by the actions of vitamin D. Newer research seeks to clarify the potential functions of calcium and vitamin D in the regulation of body weight, glucose tolerance, and ovarian function. Numerous observational studies have noted an inverse association between body weight, percent body fat, and dietary calcium intake; however, clinical trials evaluating the affect of increased calcium on weight loss have been mixed. There is a reduced incidence of insulin resistance syndrome with increasing dairy intake in overweight individuals, and serum 25 hydroxyvitamin D levels are positively correlated with insulin sensitivity. Vitamin D receptor is expressed in all calcium-regulated tissues, including the ovary; thus, calcium and vitamin D appear to be necessary for full ovarian function. This review paper will examine the important role of vitamin D and calcium in the regulation of bone, weight, glucose tolerance, and estrogen biosynthesis.

Impact of a school-based intervention on access to healthcare for underserved youth.

PURPOSE: To determine whether a multidimensional school-based intervention, which included physical and mental health services, increased adolescents' use of needed medical care and preventive care and decreased emergency room use. METHODS: A total of 2832 seventh- through twelfth-grade students in six public urban intervention schools and 2036 students in six demographically matched comparison schools completed a previously validated survey regarding health status and healthcare utilization in spring 1998 and 1999. Bivariate analyses examined the association between intervention status and Year 1/Year 2 outcomes. The multifaceted intervention included programs such as anger management groups, substance abuse prevention, tutoring, home visits, and enhanced school health services. Stepwise multivariate logistic models tested differences between the intervention and comparison groups across years, controlling for potential confounding variables [gender, age, race/ethnicity, maternal education, grade in school, school district (city or county), health status, and chronic health problems]. The interaction term for Group x Year was used to test the effect of the intervention. Multivariable modeling was also used to determine student factors independently associated with healthcare utilization. RESULTS: Respondents had a median age of 15 years, 56% were female, 51% were white, 42% were black, and 34% reported chronic health problems. In both years, over 45% of students in both groups reported not seeking medical care they believed they needed. The proportion with missed care in the intervention schools did not change, whereas the proportion with missed care in the comparison schools increased. Emergency room use decreased slightly in the intervention schools and increased slightly in the comparison schools between Year 1 and Year 2. There were no major changes in healthcare delivery in this area during the year, demonstrating the volatility of adolescents' perceived access to care. Among the student factors, health status, having a chronic condition, and being in a higher grade were independently associated with students' report of not seeking care they believed they needed. CONCLUSION: These results confirm that many adolescents have unmet healthcare needs. Those with poor health status are most likely to report underutilization and unmet needs. These findings underscore the need for comparison groups when evaluating interventions and suggest the need for better understanding of community level changes in perceived healthcare access and use.

School disconnectedness: identifying adolescents at risk.

OBJECTIVE: School connectedness, or the feeling of closeness to school personnel and the school environment, decreases the likelihood of health risk behaviors during adolescence. The objective of this study was to identify factors differentiating youth who do and do not feel connected to their schools in an effort to target school-based interventions to those at highest health risk. METHODS: The study population consisted of all students attending the 7th through 12th grades of 8 public schools. The students were asked to complete a modified version of the in-school survey designed for the National Longitudinal Study of Adolescent Health (Add Health). The school connectedness score (SCS) was the summation of 5 survey items. Bivariate analyses were used to evaluate the association between SCS and 13 self-reported variables. Stepwise linear regression was conducted to identify the set of factors best predicting connectedness, and logistic regression analysis was performed to identify students with SCS >1 standard deviation below the mean. RESULTS: Of the 3491 students receiving surveys, 1959 (56%) submitted usable surveys. The sample was 47% white and 38% black. Median age was 15. Median grade was 9th. The SCS was normally distributed with a mean of 15.7 and a possible range of 5 to 25. Of the 12 variables associated with connectedness, 7 (gender, race, extracurricular involvement, cigarette use, health status, school nurse visits, and school area) entered the linear regression model. All but gender were significant in the logistic model predicting students with SCS >1 standard deviation below the mean. CONCLUSIONS: In our sample, decreasing school connectedness was associated with 4 potentially modifiable factors: declining health status, increasing school nurse visits, cigarette use, and lack of extracurricular involvement. Black race, female gender, and urban schools were also associated with lower SCS. Further work is needed to better understand the link between these variables and school connectedness. If these associations are found in other populations, school health providers could use these markers to target youth in need of assistance.

Dependence of inessential late gene expression on early meiotic events in Saccharomyces cerevisiae.

SPR3 is one of at least nine genes which are expressed in sporulating Saccharomyces cerevisiae cells at the time of meiosis I. We show below that strains homozygous for null alleles of SPR3 are capable of normal meiosis and the production of viable ascospores. We have also monitored SPR3 expression in a series of strains that are defective in meiotic development, using an SPR3:lacZ fusion carried on a single copy plasmid. beta-Galactosidase activity occurred at wild-type levels in diploid strains homozygous for mutations in spo13, rad50, rad57 and cdc9, but was greatly reduced in strains carrying cdc8 or spo7 defects. We conclude that SPR3 expression is a valid monitor of early meiotic development, even though the gene is inessential for the sporulation process.