Calcium, dairy products, and energy balance in overweight adolescents: a controlled trial.

BACKGROUND: Dairy product and calcium consumption have been associated with modifying body fat and body weight in children and adults. OBJECTIVE: In overweight adolescent boys and girls, we aimed to determine the effect of the doubling of habitual calcium intake to the recommended intake from dairy or calcium carbonate on energy balance and purported mechanisms including fecal fat excretion, macronutrient use, and parathyroid hormone suppression. DESIGN: Twenty-five girls with a mean (±SD) BMI (in kg/m(2)) of 33 ± 5 and 17 boys with a BMI of 28 ± 5, aged 12-15 y, participated in two 3-wk controlled feeding sessions that used a crossover design in random order as a summer research camp. In one session, 756 mg Ca/d was consumed; in the other session, an additional 650 mg Ca/d was provided as dairy or calcium carbonate supplements that were matched to the control in macronutrient content. Total energy and macronutrient intakes were controlled and were the same for the 2 sessions for each subject. Primary outcome measures were energy balance, fecal fat excretion, lipid oxidation, and postprandial energy expenditure. RESULTS: There were no effects of quantity or source of calcium on energy or fat balance, despite calcium-induced increases (P <0.01) in postprandial serum parathyroid hormone suppression. CONCLUSION: These data lend little evidence to support the proposed mechanisms for the relation between an increase in calcium intake from calcium carbonate or dairy and weight loss or weight maintenance in children. This trial was registered at clinicaltrials.gov as NCT00592137.

Obesity augments calcium-induced increases in skeletal calcium retention in adolescents.

CONTEXT: Overweight adolescents have low bone mineral content for weight and are at increased risk for fractures. OBJECTIVE: The aim was to determine whether overweight and obesity influence the positive relationship between dietary calcium intake and skeletal calcium retention in adolescents. DESIGN: Analysis of pooled data from calcium balance studies in adolescents. SETTING: Participants each underwent a 3-wk calcium balance study in a controlled environment. PARTICIPANTS: Participants included 280 White, Black, and Asian boys (n = 73) and girls (n = 207) ages 10-16 yr. MAIN OUTCOME MEASURE: The relationship among body mass index (BMI), calcium intake, and calcium retention was modeled using linear regression. RESULTS: Calcium intake, BMI, sex, race, and age explained 27.9% of the variation in calcium retention. At low calcium intakes, there was no effect of BMI on skeletal calcium retention, but at higher calcium intakes, BMI increased skeletal calcium retention. CONCLUSIONS: Greater gains in calcium retention occur with increases in calcium intake in adolescents with higher BMI compared with those with lower BMI. Additional studies are needed to investigate whether increasing calcium intake reduces the increased risk of fracture associated with overweight and obesity in adolescents.

Fructo-oligosaccharides and calcium absorption and retention in adolescent girls.

BACKGROUND: Several studies have shown a positive effect of fructo-oligosaccharides on calcium absorption and retention in animals and humans. Effects of levels of these pre-biotics that can be functionally incorporated into manufactured foods, have not been studied in controlled feeding studies. OBJECTIVES: This study was designed to evaluate the effect of 9 g/d of fructo-oligosaccharides as part of a controlled diet on calcium absorption and retention in adolescent girls. DESIGN: Fourteen healthy adolescent girls aged 11-13 y were studied in a metabolic setting for two 3-week periods separated by a 2-week washout period. In a randomized, double-blinded, crossover design, the teens received a diet containing either 9 g/d oligofructose-enriched inulin in a calcium-fortified cereal or the control cereal with no inulin. Both diets contained ~1500 mg calcium daily. Calcium retention was determined on the third week of each period. On day 14 of the diet period, fractional calcium absorption was determined from the enrichment of (44)Ca in 4-day urine collections. RESULTS: Calcium absorption (67 ± 3 vs. 66 ± 3%) and retention (409 ± 394 vs. 464 ± 241 mg/d) were not significantly different when diets contained 9 g/d oligofructose-enriched inulin or not in a calcium-fortified cereal. CONCLUSIONS: Daily consumption of cereal containing a combination of short- and long-chain fructo-oligosaccharides as part of a controlled diet did not benefit calcium absorption or retention in adolescent girls. Lack of response to the prebiotic in this cohort may relate to their already high calcium absorption efficiency.

Calcium requirements and metabolism in Chinese-American boys and girls.

Calcium requirements of North American adolescents were set at 1300 mg/day based on data from white girls. Calcium requirements for Asian-American adolescents have not been studied. Using metabolic balance protocols and a range in calcium intakes, skeletal calcium retention was determined in Chinese-American adolescents. A sample of 29 adolescents, 15 boys aged 12 to 15 years and 14 girls aged 11 to 15 years, was studied twice on paired calcium intakes ranging between 629 to 1835 mg/day using a randomized-order crossover design. Calcium absorption and bone turnover rates using double-stable calcium isotope kinetic analysis on two calcium intakes per subject were measured and compared in boys and girls. Girls and boys had low habitual mean calcium intakes of 648 and 666 mg/day, respectively, and low mean serum 25-hydroxyvitamin D concentrations of 19.1 and 22.2 ng/mL, respectively. True fractional calcium absorption varied inversely with calcium load. Boys had significantly higher bone turnover rate than girls at the same calcium intake. Calcium retention increased with calcium intake; calcium intakes to achieve maximal calcium retention were 1100 mg/day in boys and 970 mg/day in girls. Recommendations for calcium requirements should be lowered for Chinese-American adolescents.

Are complex psychotherapies more effective than biofeedback, progressive muscle relaxation, or both? A meta-analysis.

A meta-analysis of 26 studies was conducted to assess whether more complex forms of psychotherapy would be superior to control treatments of either biofeedback, progressive muscle relaxation, or both. Consistent with hypotheses, more complex treatments provided a small, significant improvement over biofeedback and progressive muscle relaxation (r = .09). A subset of the more complex behavioral treatments accounted for most of this small incremental effectiveness of more complex treatments (r = .15). Possible sources of this incremental effectiveness are discussed.

Processing abilities associated with math skills in adult learning disability.

This study evaluated college adults (N = 138) referred for learning problems using a Cattell-Horn-Carroll based intelligence measure (Woodcock Johnson-Revised: WJ-R) and spatial and executive function neuropsychological measures to determine processing abilities underlying math skills. Auditory and visual perceptual (WJ-R Ga and Gv), long- and short-memory (WJ-R Glr and Gsm), crystallized and fluid intellectual (WJ-R Gc and Gf), and spatial and executive function (Judgment of Line Orientation [JLO] and Category Test) measures differentiated those with and without math deficits. Multiple regression revealed selective processing abilities (Gf, JLO, and Category) predicting about 16% of the variance in math skills after variance associated with general intelligence (also about 16%) was removed. Cluster analysis found evidence for a selective spatial deficit group, a selective executive function deficit group and a double deficit (spatial and executive function) group. Results were discussed in relation to a double deficit hypothesis associated with developmental dyscalculia.

Processing abilities associated with phonologic and orthographic skills in adult learning disability.

Measures of orthographic and phonologic skills were related to co-normed Woodcock Johnson-Revised (WJ-R) cognitive measures in 138 college age, learning problem adults. Only orthographic deficits were associated with a processing disorder (p<.001). Selective processing abilities were associated with phonologic (p<.001, Delta adj R(2)=.053) and orthographic (p<.001, Delta adj R(2)=.047) skills after removal of variance associated with general intelligence. Analyses found common processing abilities across both phonologic and orthographic skills for WJ-R visual processing (-Gv) and short-term memory processing factors (Gsm) (p<.001). Cluster analysis established a phonologic deficit and a double deficit (phonologic and orthographic) group. Discussion relates results to the differences between adult and child reading decoding deficits, the lack of a selective orthographically impaired subtype of dyslexia, and the evidence of visual processing compensation for reading problems.

Effects of September 11 on patients with obsessive compulsive disorder.

Effects of the September 11, 2001 terrorist attacks in the USA were investigated in 25 patients with obsessive compulsive disorder and 27 normal controls 4-6 months after the attacks. Participants completed a 15-item questionnaire to retrospectively assess changes in mood, cognition, behavior and somatic complaints since September 11, 2001. Overall, both patients with obsessive compulsive disorder and normal controls reported minor changes in mood, behavior and somatic complaints. However, normal controls reported severe to extreme initial impact, slightly more cognitive symptoms (uncertainty about the future, intrusive recollections and greater desire to be with loved ones) and a slightly greater degree of overall impact on emotion and behavior at 1, 2 and 3 months after September 11 than did patients with obsessive compulsive disorder. Results support previous research that has found a relatively minor lasting impact of September 11 on both clinical and normal populations. Differences in cognition and coping mechanisms between normal controls and patients with obsessive compulsive disorder are proposed.

Sonic hedgehog patterning in chick neural plate is antagonized by a Wnt3-like signal.

Sonic hedgehog (Shh) patterns the dorsal-ventral axis of the neural tube by promoting the differentiation of ventral neural cell types while suppressing dorsal neural fates. Other signals impinge upon the Shh response, biasing the differentiation of a cell. Three dorsally expressed transforming Wnts, of which the most broadly expressed is Wnt3, may be among the signals that influence the Shh response. We demonstrate that activation of Wnt signaling results in an inhibition of the Shh response in neural tissue. Additionally, we show that the expression pattern of chick Wnt3 is consistent with a role in neural patterning. These results indicate that differentiating neural tube cells, besides integrating signals from Hedgehogs and BMPs, may also incorporate a Wnt response to make cell fate decisions.

Wnt signaling is required at distinct stages of development for the induction of the posterior forebrain.

One of the earliest manifestations of anteroposterior pattering in the developing brain is the restricted expression of Six3 and Irx3 in the anterior and posterior forebrain, respectively. Consistent with the role of Wnts as posteriorizing agents in neural tissue, we found that Wnt signaling was sufficient to induce Irx3 and repress Six3 expression in forebrain explants. The position of the zona limitans intrathalamica (zli), a boundary-cell population that develops between the ventral (vT) and dorsal thalamus (dT), is predicted by the apposition of Six3 and Irx3 expression domains. The expression patterns of several inductive molecules are limited by the zli, including Wnt3, which is expressed posterior to the zli in the dT. Wnt3 and Wnt3a were sufficient to induce the dT marker Gbx2 exclusively in explants isolated posterior to the presumptive zli. Blocking the Wnt response allowed the induction of the vT-specific marker Dlx2 in prospective dT tissue. Misexpression of Six3 in the dT induced Dlx2 expression and inhibited the expression of both Gbx2 and Wnt3. These results demonstrate a dual role for Wnt signaling in forebrain development. First, Wnts directed the initial expression of Irx3 and repression of Six3 in the forebrain, delineating posterior and anterior forebrain domains. Later, continued Wnt signaling resulted in the induction of dT specific markers, but only in tissues that expressed Irx3.