Matthew M. Davis

Prevalence and Determinants of Insulin Resistance Among U.S. Adolescents A population-based study

OBJECTIVE—We sought to examine the distribution of insulin and homeostasis model assessment of insulin resistance (HOMA-IR) and associations of HOMA-IR with sex, race/ethnicity, age, and weight status, as measured by BMI, among U.S. adolescents. RESEARCH DESIGN AND METHODS—Of 4,902 adolescents aged 12–19 years who participated in the National Health and Nutrition Examination Survey 1999–2002, analysis was performed for a nationally representative subsample of 1,802 adolescents without diabetes who had fasting laboratory measurements. The main outcome measure was HOMA-IR, calculated from fasting insulin and glucose and log transformed for multiple linear regression analyses. RESULTS—In adjusted regression models that included age and weight status, girls had higher HOMA-IR than boys and Mexican-American children had higher HOMA-IR levels than white children. There were no significant differences in adjusted HOMA-IR between black and white children. Obese children (BMI ≥95th percentile) had significantly higher levels of HOMA-IR compared with children of normal weight (BMI <85th percentile) in adjusted comparisons (mean HOMA-IR 4.93 [95% CI 4.56–5.35] vs. 2.30 [2.21–2.39], respectively). Weight status was by far the most important determinant of insulin resistance, accounting for 29.1% of the variance in HOMA-IR. The prevalence of insulin resistance in obese adolescents was 52.1% (95% CI 44.5–59.8). CONCLUSIONS—Obesity in U.S. adolescents represents the most important risk factor for insulin resistance, independent of sex, age, or race/ethnicity. The prevalence of insulin resistance in obese children foreshadows a worrisome trend for the burden of type 2 diabetes in the U.S.

Decline in Varicella-Related Hospitalizations and Expenditures for Children and Adults After Introduction of Varicella Vaccine in the United States

Objective. Universal childhood immunization against varicella in the United States, first recommended in 1995, was predicted to lead to significant decreases in varicella-related hospitalization rates and corresponding charges. Previous studies have not found such effects. We studied trends in varicella-related hospitalization rates and associated charges before and after introduction of varicella vaccine. Methods. We examined hospitalization and charge data from the Nationwide Inpatient Sample for the years 1993–2001, representative of national hospitalization patterns for children and adults. We derived weighted estimates of population-adjusted, varicella-related hospitalization rates and inflation-adjusted, varicella-related hospital charges. Results. The annual varicella-related hospitalization rate exceeded 0.5 hospitalizations per 10 000 US population from 1993 to 1995, declined to 0.26 per 10 000 by 1999, and again halved to 0.13 per 10 000 by 2001. Hospitalization rates declined most substantially among individuals primarily targeted for vaccination (0- to 4-year-old children) but decreased among youths aged 5 to 19 years and among adults as well. Concomitantly, varicella-related hospital charges declined from

ACAT2 Is Localized to Hepatocytes and Is the Major Cholesterol-Esterifying Enzyme in Human Liver

161.1 million (95% confidence interval:

A National Survey of Pediatric Critical Care Resources in the United States

130.5 million–

Influenza Vaccination as Secondary Prevention for Cardiovascular Disease

191.8 million) in 1993 to

A national survey of physician practices regarding influenza vaccine.

66.3 million (95% confidence interval:

When insurance status is not static: insurance transitions of low-income children and implications for health and health care.

50.9 million–

Childhood vaccine purchase costs in the public sector: Past trends, future expectations

81.7 million) in 2001 (all 2001

Variation in the use of intracranial-pressure monitoring and mortality in critically ill children with meningitis in the United States.

US). Among expected primary payers, inflation-adjusted declines in varicella-related hospital discharges–related charges accrued to Medicaid, private insurance, and “other” payers (including uninsured and self-pay) but not to Medicare. Conclusions. This national analysis indicates a clinically and statistically significant reduction in varicella-related hospitalizations for children and adults associated with childhood varicella immunization in the United States and a corresponding significant decrease in hospital charges.

Planning the next wave of SCHIP research.

Background—Two acyl-coenzyme A:cholesterol acyltransferase (ACAT) genes, ACAT1 and ACAT2, have been identified that encode 2 proteins responsible for intracellular cholesterol esterification. Methods and Results—In this study, immunohistology was used to establish their cellular localization in human liver biopsies. ACAT2 protein expression was confined to hepatocytes, whereas ACAT1 protein was found in Kupffer cells only. Studies with a highly specific ACAT2 inhibitor, pyripyropene A, in microsomal activity assays demonstrated that ACAT2 activity was highly variable among individual human liver samples, whereas ACAT1 activity was more similar in all specimens. ACAT2 provided the major cholesterol-esterifying activity in 3 of 4 human liver samples examined. Conclusions—The data suggest that in diseases in which dysregulation of cholesterol metabolism occurs, such as hypercholesterolemia and atherosclerosis, ACAT2 should be considered a target for prevention and treatment.