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[1] Major and trace element and Sr, Nd, and Pb isotope data for lavas from 12 seamounts along the western (older) 1500 km section of the Louisville Seamount Chain in the southwest Pacific show remarkably uniform compositions over a ∼30-40 Myr period of volcanism. All 56 samples analyzed are alkalic to transitional in composition. Unlike Hawaiian volcanoes, Louisville volcanoes appear not to pass through a sequence of evolutionary stages characterized by older tholeiitic basalts overlain by incompatible element enriched alkalic and silica-undersaturated lavas. The youngest lavas from a given Louisville seamount tend to have the least enriched incompatible element compositions. This unusual chemical evolution may be the result of re-melting of heterogeneous hot spot mantle that was partially depleted during the earlier, age progressive stages. The oldest Louisville seamounts were constructed close to the extinct Osbourn Trough spreading center, located north of the chain, but age-progressive lavas from these older seamounts are not significantly different to lavas from younger seamounts. This may indicate that spreading at this fossil ridge ceased several tens of millions of years before the oldest Louisville seamounts were constructed. Large fracture zones apparently had no significant effects on the composition of Louisville magmatism. However, lavas from the central part of the Louisville Seamount Chain, where volcanoes are smaller and more widely spaced, tend to have more variable and more enriched compositions. We suggest this may reflect smaller degrees of melting resulting from greater lithosphere thickness, and hence a shorter melting column for this section of the Louisville Seamounts.

OBJECTIVES. Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is the most common inherited disorder of adrenal steroid biosynthesis. Patients with the classic form of CAH show androgen excess, with or without salt wasting. There are few studies reporting on higher rates of overweight and obesity among children with CAH. In addition to its role in the regulation of energy balance, leptin is involved in various endocrine and metabolic pathways. In this context, elevated serum leptin levels were reported recently for patients with CAH and were thought to be involved in the development of obesity among these patients. Therefore, the aim of this study was to analyze BMI values, compared with population-based references, for children and adolescents with CAH. Possible contributing factors, such as glucocorticoid therapy, skeletal maturation, birth weight and length, and parental BMI, were correlated with current BMI SD scores (SDS). In addition, the implications of serum leptin levels, corrected for BMI, gender, and Tanner stage, were investigated.METHODS. We performed a cross-sectional retrospective study of 89 children and adolescents with CAH (48 female and 41 male subjects; age: 0.2-17.9 years) who presented in our outpatient department during 1 year. All individuals had classic CAH, confirmed with molecular genetic analyses, and received substitution therapy (glucocorticoids and mineralocorticoids, if necessary). The quality of therapy was monitored in follow-up visits every 3 to 6 months, on the basis of clinical presentation and laboratory measurement findings according to current guidelines. We grouped the patients into salt wasting and simple virilizing groups, as well as according to current metabolic control. Leptin levels were measured with a commercial radioimmunoassay and calculated as SDS. For statistical analyses, standard parametric and nonparametric methods were used.RESULTS. The chronologic ages of the children with CAH were between 0.20 and 17.9 years (mean Ϯ SD: 8.9 Ϯ 4.6 years). The BMI SDS of the whole group ranged from Ϫ2.7 to 4.3 (mean Ϯ SD: 0.88 Ϯ 1.3) and was significantly elevated above 0.www.pediatrics.org/cgi

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