The influence of body composition on the six-minute walk test in Chilean preschool and school children / Influencia de la composición corporal en el test de la caminata de seis minutos en preescolares y escolares chilenos

Background: the six minutes' walk test (6MWT) measures submaximal physical activity. Objective: this study determines the association of children´s nutritional status and body composition with the results of the 6MWT. Methods: a sample of 1419 Chilean children, 4 to 10 years of age, were assessed including anthropometry, body composition by validated equations, the 6MWT test, and in 50 % of the sample heart rate prior the test, at one minute into the test, and at one minute posttest with a Polar watch. Results: the distance walked ranged from 473.1 ± 47.8 meters in preschool children to 584.2 ± 65.7 meters in school children. In heart rate there was a significant difference between obese and eutrophic children. The distance walked in the 6MWT was positively associated with fat-free mass (p < 0.05) and BMI (R2 = 0.49). Body composition influences 6MWT quartile distribution, as well as nutritional status. Age and height explained 49 % of the variance (R2 = 0.42 and 0.47, respectively) in the 6MWT, and there are significant differences in this variable by sex, body composition, and nutritional status. Conclusions: body composition was associated with walking performance in children. Thus, it is important to evaluate height and body composition when assessing the six-minute walk test because of this important relationship (AU)

Introducción: el test de la marcha de seis minutos (TM6M) mide una actividad física submáxima. Este estudio evaluó el efecto del test de la marcha sobre la composición corporal y el estado nutricional en niños. Métodos: en una muestra de 1419 niños chilenos de 4 a 10 años de edad se evaluaron la antropometría, la composición corporal por ecuaciones validadas, el TM6M y, en el 50 % de la muesta, la frecuencia cardíaca mediante un reloj Polar. Resultados: la distancia caminada varió desde 473,1 ± 47,8 metros en los niños preescolares hasta 584,2 ± 65,7 metros en los escolares. En la frecuencia cardíaca hubo una diferencia significativa entre niños obesos y eutróficos. La distancia caminada se asoció positivamente con la masa libre de grasa (R2 = 0,37) y el IMC (R2 = 0,49). Por otra parte, la composición corporal varía en función de los cuartiles de composición corporal y el estado nutricional. La edad y la altura explicaron el 49 % de la varianza de la prueba (R2 = 0,42 and 0,47, respectivamente). Existen diferencias significativas en la distancia recorrida en el TM6M en función del sexo, la composición corporal y el estado nutricional. Conclusiones: composición corporal, talla e IMC se asociaron a la distancia recorrida en el TM6M. Por tanto, se sugiere medir estas variables cuando se evalúe el test de marcha de seis minutos (AU)

Anthropometric indicators as predictors of total body fat and cardiometabolic risk factors in Chilean children at 4, 7 and 10 years of age.

BACKGROUND/OBJECTIVE: To compare the association between anthropometric indicators of global and central obesity as predictors of total body fat (TBF) and cardiometabolic risk factors in children. SUBJECTS/METHODS: A total of 1044 children were evaluated at 4 years (n=320), 7 years (n=1044) and 10 years (n=483). The following anthropometric indices were determined: body mass index (BMI) for age (BAZ, WHO), waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR). To estimate TBF we used validated predictive equations. We measured blood sample concentrations of glucose, insulin, triglycerides, total cholesterol, Low-density lipoprotein (LDL) and High-density lipoprotein (HDL), adiponectin, C-reactive protein (CRP) and Insulin-like growth factor-1 (IGF-1). RESULTS: Adiposity and cardiometabolic markers, particularly those related to glucose metabolism increased from 4 years to 10 years. BAZ and WC were highly correlated to body fat at all ages (all r>0.8) but at 10 years WC was more strongly correlated than BAZ (r=0.94 WC vs r=0.88 BAZ, P<0.05); conversely, WHtR was significantly associated with body fat from 7 years (r=0.85) and 10 years (r=0.88). WHR was unrelated all over the period studied at all ages. Anthropometrical adiposity indicators became associated to cardiometabolic markers only from 7 years on with associations being slightly higher at 10 years, particularly for adiponectin and lipid markers. At all ages, BAZ, WC and WHtR performed similarly as cardiometabolic markers (P<0.05) while WHR was a slightly weaker marker. CONCLUSIONS: Relationship between anthropometrical indicators of adiposity and cardiometabolic markers becomes stronger from 7 years onwards; BAZ, WC and WHtR perform similarly as markers of cardiometabolic risk at least until 10 years of age.

Evaluation of simple body composition methods: assessment of validity in prepubertal Chilean children.

BACKGROUND/OBJECTIVE: The aim of this study was to assess the validity of body fatness estimations based on skinfolds and bioelectrical iImpedance analyses (BIA) measurements compared to a three-component model (3C model) in prepubertal Chilean children, considering potential differences by sex and nutritional status. SUBJECTS/METHODS: Four hundred and twenty four Chilean children (198 females and 226 males) were assessed for body composition. Body fat percentage (BF%) was evaluated by Skinfold equations (Slaughter, Ramirez and Huang) and Bioelectrical impedance (BIA: Tanita BC-418MA) using both the equipment and the Ramirez equation. Measurements based on a 3C model constructed from total body water estimates by isotope dilution and from body volume estimates by air displacement plethysmography were used as gold standard. RESULTS: Coefficient of determination (R2) values were higher in overweight and in the whole group of both gender. All slopes were differed significantly from 1, and most intercepts were significantly different from 0. Skinfold Equations: an underestimation of BF% was found for all equations, being higher with the Slaughter equation. BIA: Tanita underestimated BF% in all groups, whereas Ramirez equation shows an overestimation. CONCLUSIONS: Skinfolds and bio-impedance equations serve well to rank children according to their BF%. However, these methods are not accurate for describing body composition in prepubertal Chilean children.

Early adiposity rebound is associated with metabolic risk in 7-year-old children.

BACKGROUND: Early adiposity rebound (AR <5 years) has been consistently associated with increased obesity risk, but its relationship with metabolic markers is less clear; in addition, the biologic mechanisms involved in these associations have not been established. OBJECTIVE: The objective of this study was to assess the association between timing of AR and metabolic status at age 7 years, evaluating the potential role of adiposity, adipose functionality and skeletal maturation in this association. DESIGN: We estimated the age of AR from the body mass index (BMI) trajectories from 0 to 7 years in 910 children from the Growth and Obesity Chilean Cohort Study (GOCS). At 7 years, we measured waist circumference (WC) and blood glucose, insulin, triglycerides and high-density lipoprotein-cholesterol levels and constructed a metabolic risk score. We also measured percent fat mass (adiposity), plasma concentrations of leptin and adiponectin (adipose functionality) and bone age using wrist ultrasound (skeletal maturation). RESULTS: We found that 44% of the children had an AR <5 years. Earlier AR was associated with larger WC (ß: 5.10 (95% confidence interval (CI): 4.29-5.91)), higher glucose (ß: 1.02 (1.00-1.03)), insulin resistance (ß Homeostatic Model Assessment: 1.06 (1.03-1.09)), triglycerides (ß: 10.37 (4.01-6.73)) and adverse metabolic score (ß: 0.30 (0.02-0.37)). Associations decreased significantly if adiposity was added to the models (i.e. ß WC: 0.85 (0.33-1.38)) and, to a lesser extent, when adipokines (i.e. ß WC: 0.73 (0.14-1.32)) and skeletal maturation (i.e. ß WC: 0.65 (0.10-1.20)) were added. CONCLUSION: In GOCS children, AR at a younger age predicts higher metabolic risk at 7 years; these associations are mostly explained by increased adiposity, but adipose dysfunction and accelerated skeletal maturation also have a role.

DNA damage induced by micro- and nanoparticles--interaction with FPG influences the detection of DNA oxidation in the comet assay.

Reliable methods for evaluation of toxicity from particles, such as manufactured nanoparticles, are needed. One promising tool is the comet assay, often used to measure DNA breaks (strand breaks and alkali-labile sites) as well as oxidatively damaged DNA, the latter by addition of specific DNA repair enzymes such as formamidopyrimidine DNA glycosylase (FPG). The aim of this study was to investigate the use of the comet assay for analysis of DNA oxidation by a range of micro- and nanoparticles in the lung cell lines A549 and BEAS-2B and to test the hypothesis that nanoparticles present in the cells during the assay performance may interact with FPG. This was done by investigating the ability of micro- and nanoparticles (stainless steel, subway particles, MnO(2), Ag, CeO(2), Co(3)O(4), Fe(3)O(4), NiO and SiO(2)) to induce DNA breaks, oxidatively damaged DNA (FPG sites, dominantly 8-oxoguanine), intracellular production of reactive oxygen species (ROS) and non-cellular oxidation of the DNA base guanine, as well as by studying interactions of the particles and their released ions with FPG. Several particles caused DNA breaks, but low levels of FPG sites. The ability of FPG to detect DNA oxidation induced by a photosensitiser was however shown. An oxidative capacity of the particles was indicated by increased levels of intracellular ROS, and especially Ag and subway particles caused non-cellular oxidation of guanine. Incubation of FPG with the particles led to less FPG activity, particularly with nanoparticles of Ag but also with CeO(2), Co(3)O(4) and SiO(2). Further investigations of these particles revealed that for Ag, the decreased activity was mainly due to released Ag ions, whereas for CeO(2) and Co(3)O(4), FPG interactions were due to the particles. We conclude that measurement of oxidatively damaged DNA in cells exposed to nanoparticles may be underestimated in the comet assay due to interactions with FPG.

Extrapulmonary small cell carcinoma following augmentation enterocystoplasty.

Tumours developing after urinary tract or bladder reconstruction with intestinal tissue have well been described. Adenocarcinomas and transitional cell carcinomas are the most frequent histological features. We report here a case of small cell carcinoma developing after augmentation enterocystoplasty. This rare observation is an opportunity to review the literature about extrapulmonary small cell carcinoma and tumours developing after uro-intestinal reconstruction surgery.

Nutritional status, food consumption and physical activity among Chilean school children: a descriptive study.

OBJECTIVE: To assess the nutritional status, food consumption and physical activity (PA) habits of Chilean school children, as a baseline for developing an educational intervention. DESIGN: Cross-sectional study. SUBJECTS: A total of 1701 children from 3rd to 7th grade in nine schools located in three geographical regions. METHODS: We determined body mass index, food consumption (quantified FFQ which we categorised into five groups), PA in terms of TV viewing and frequency of after school PA. The data were analysed according to age, nutritional status and gender. A logistic regression analysis was performed using obesity as outcome. RESULTS: Obesity was higher among boys; younger children presented higher prevalence in both genders. Daily intake of dairy products varied between 240 and 308 g, fruits/vegetables, between 197 and 271 g, energy-dense foods between 343 and 460 g. In all, 22.3 and 47% of the children watched over 3 h of TV during the week and weekend, respectively. Older children watched significantly more TV during the week, while on weekends all children increased this time significantly. Boys were more active than girls after school. The logistic regression analysis showed a significant association between obesity and low intake of dairy products. CONCLUSIONS: Prevalence of obesity among Chilean children is high. Although TV time, intake of energy dense foods and fruits/vegetables appeared as risk factors for obesity, only dairy consumption was significantly associated with obesity. SPONSORSHIP: FAO

School-based obesity prevention in Chilean primary school children: methodology and evaluation of a controlled study.

OBJECTIVE: To assess the impact of a 6 months nutrition education and physical activity intervention on primary school children through changes in adiposity and physical fitness. DESIGN: Longitudinal school-based controlled evaluation study. SUBJECTS: Children from 1st to 8th grade, 2141 in intervention and 945 in control schools. INTERVENTION: Nutrition education for children and parents, 'healthier' kiosks, 90 min of additional physical activity (PA) weekly, behavioral PA program and active recess. MEASUREMENTS: Adiposity indices (BMI, BMI Z-score, triceps skinfold thickness (TSF), waist circumference and physical fitness (20 m shuttle run test and lower back flexibility). RESULTS: Positive effect on adiposity indices (except TSF) was observed in boys (P<0.001 for BMI Z), while both physical fitness parameters increased significantly in both boys (P<0.001 for each test) and girls (P<0.0001 for each test). A differential effect in BMI Z was observed according to baseline nutritional status. CONCLUSIONS: This intervention showed a robust effect on physical fitness in both genders and decreased adiposity only in boys.

Trends in overweight and obesity prevalence in Chilean children: comparison of three definitions.

OBJECTIVE: To compare trends in prevalence of overweight and obesity among Chilean children using three different criteria. METHODS: Descriptive cross-sectional school-based study to analyse these trends in 6-y-old boys and girls who entered first grade in 1987, 1990, 1993, 1996 and 2000. Gender-specific prevalence of overweight and obesity were determined with three criteria: weight for height (W-H) Z-scores compared to NCHS 1977; present reference used by the Ministry of Health; and body mass index (BMI) compared to the revised US CDC Growth Charts with cut-off values of P85-95 and P-95 and IOTF reference with cut-offs extrapolated from an adult BMI of 25 and 30. RESULTS: The prevalence of overweight determined by W-H (WHO) increased from 15% in 1987 to 20% in 2000 for boys and from 17.2 to 21.8% for girls. With BMI-CDC, the increase was from 13.2 to 19.2% for boys and 12 to 18.5% for girls. With BMI-IOTF, rates were very similar. Prevalence of obesity using W-H (WHO) increased from 6.5% in 1987 to 17% in 2000 for boys and from 7.8 to 18.6% for girls. Using BMI-CDC, the increase was from 5.1 to 14.7% for boys and from 4 to 15.8% for girls; using BMI-IOTF prevalence estimates were much lower. CONCLUSIONS: Obesity prevalence in children has increased over time, and trends are similar independent of criteria. The reference used to define prevalence is important since it provides different estimates. Policy makers should be aware that a spurious drop in prevalence may appear if the IOTF reference is compared to the other criteria.

Nutrition transition in Latin America: the case of Chile.

The nutritional situation of Latin America is changing rapidly from one characterized by underweight and stunting to one where chronic diseases such as cancer, cardiovascular disease, and type 2 diabetes are increasingly prevalent. In Chile, under-nutrition has virtually disappeared, but rising obesity rates and risk factors for chronic diseases indicate the need to modify existing programs and emphasize prevention of diet-related chronic diseases.

Transfer of bacteria from fabrics to hands and other fabrics: development and application of a quantitative method using Staphylococcus aureus as a model.

AIMS: To develop and apply a quantitative protocol for assessing the transfer of bacteria from bleached and undyed fabrics of 100% cotton and 50% cotton + 50% polyester (poly cotton) to fingerpads or other pieces of fabric. METHODS AND RESULTS: Test pieces of the fabrics were mounted on custom-made stainless steel carriers to give a surface area of 1 cm in diameter, and each piece seeded with about 10(5) cfu of Staphylococcus aureus from an overnight broth culture; the inoculum contained 5% fetal bovine serum as the soil load. Transfer from fabric to fabric was performed by direct contact using moist and dry fabrics. Transfers from fabrics to fingerpads of adult volunteers were tested using moist, dry and re-moistened pieces of the fabrics, with or without friction during the contact. Bacterial transfer from fabrics to moistened fingerpads was also studied. All the transfers were conducted under ambient conditions at an applied pressure of 0.2 kg cm(-2). After the transfer, the recipient fingerpads or fabric pieces were eluted, the eluates spread-plated, along with appropriate controls, on tryptic soy agar and the percentage transfer calculated after the incubation of the plates for 24 h at 37 degrees C. CONCLUSION: Bacterial transfer from moist donor fabrics using recipients with moisture was always higher than that to and from dry ones. Friction increased the level of transfer from fabrics to fingerpads by as much as fivefold. Bacterial transfer from poly cotton was consistently higher when compared with that from all-cotton material. SIGNIFICANCE AND IMPACT OF THE STUDY: The data generated should help in the development of better models to assess the role fabrics may play as vehicles for infectious agents. Also, the basic design of the reported methodology lends itself to work with other types of human pathogens.

Obesity trends in Latin America: transiting from under- to overweight.

Latin America is undergoing a rapid demographic and nutritional transition. A recent WHO/PAHO survey on obesity in the region revealed an increasing trend in obesity as countries emerge from poverty, especially in urban areas. In contrast, in middle income countries, obesity tends to decline as income increases; this is especially so in women. Dietary changes and increasing inactivity are considered the crucial contributory factors that explain this rise. The end result is a progressive rise in overweight and obesity, especially in low income groups who improve their income and buy high fat/high carbohydrate energy-dense foods. Intake of these foods increases to the detriment of grains, fruits and vegetables. Most aboriginal populations of the Americas have changed their diet and physical activity patterns to fit an industrialized country model. They now derive most of their diet from Western foods and live sedentary and physically inactive lives. Under these circumstances they develop high rates of obesity, insulin resistance and type 2 diabetes. Supplementary feeding programs are common in the region; the number of beneficiaries significantly exceeds the malnourished. Weight-for-age definition of undernutrition without assessment of length will overestimate the dimension of malnutrition and neglect the identification of stunted overweight children. Providing food to low income stunted populations may be beneficial for some, although it may be detrimental for others, inducing obesity especially in urban areas. Defining the right combination of foods/nutrients, education and lifestyle interventions that are required to optimize nutrition and health is a present imperative.

Thermotropic and lyotropic liquid crystalline phases of rigid aromatic amphiphiles

Rodlike amphiphilic molecules that contain exclusively aromatic building-blocks and no flexible alkyl chains have been synthesized and their mesomorphic properties investigated. These novel compounds bear diol head groups of different size (2,3-dihydroxypropyloxy or 5,6-dihydroxy-3-oxahexyloxy groups) at one end of a biphenyl unit, various aromatic segments (benzyloxy, 4-, 3-, or 2-methylbenzyloxy, phenoxy groups) at the other, and additional methyl substituents in different positions. They were synthesized by using Suzuki cross-coupling reactions as the key steps. Their thermotropic mesomorphism was investigated by means of polarized light optical microscopy, differential scanning calorimetry, and, for enantiotropic phases, by X-ray scattering. The liquid crystallinity of this class of compounds is influenced by protic solvents, such as water and glycerol. Dependent on the temperature and the solvent content, different SA phases were found. Several mesophases resulting from the frustration of these layer structures (e.g., different columnar phases, optical isotropic mesophases, and nematic phases) were also present. The smectic phases have different degrees of intercalation (SAd, SA2). The columnar phases are supposed to be ribbon structures that result from the collapse of the smectic layers. They occur in some pure compounds or they are induced upon the addition of protic solvents. The particular phase sequences of the different compounds depend mainly on the position of the methyl substituents at the biphenyl cores and are largely determined by the degree of intercalation of the aromatic cores.

Ambulatory physiological status monitoring during a mountaineering expedition.

OBJECTIVE: To evaluate an ambulatory physiological monitoring system during a mountaineering expedition. We hypothesized that the Environmental Symptoms Questionnaire, combined with frequent measurement of oxygen saturation and core temperature, would accurately identify cases of environmental illness. METHODS: Twelve military mountaineers took a daily Environmental Symptoms Questionnaire, monitored fingertip oxygen saturations, and recorded core temperatures while climbing a 4,949-m peak. Illnesses identified by the system were compared with those identified by spontaneous reports. RESULTS: The system correctly identified one case of high-altitude pulmonary edema and two illnesses that were not reported to the physician (one case of acute mountain sickness and one of self-limited symptomatic desaturation). However, it did not identify two illnesses that were severe enough to preclude further climbing (one case of sinus headache and one of generalized fatigue). CONCLUSIONS: Our monitoring system may complement, but cannot replace, on-site medical personnel during mountaineering expeditions.

[Height increase among school children assisting to first grade during the last decade in Chile]. / Aumento en la estatura de escolares que ingresaron al primer año básico durante la última década.

BACKGROUND: In most developing countries, the prevalence of height deficit among schoolchildren correlates well with poverty. Therefore this indicator is frequently used to monitor the quality of life of a population. AIM: To assess the changes in height of children entering first grade during the last decade. MATERIAL AND METHODS: The records of the Chilean Board of School Assistance, that recollects anthropometric data on 80% of the national population of school age children, were used. For the purposes of this analysis, data from first graders in 1987, 1990, 1993 and 1996 were considered. The absolute variation of height, height for age Z scores were calculated. Children were grouped by sex and by age, using 7 years old as the cutoff value. RESULTS: During the last decade, height has increased significantly in men and women and in all ages. The increase has been greater in younger children. There is a higher proportion of males than women with height deficit. CONCLUSIONS: The increase in height can be attributed to the improvement in social, economic and biological conditions of our population as well as to the targeting strategies of existing food programs.

Thermoregulatory responses to cold water at different times of day.

This study examined how time of day affects thermoregulation during cold-water immersion (CWI). It was hypothesized that the shivering and vasoconstrictor responses to CWI would differ at 0700 vs. 1500 because of lower initial core temperatures (T(core)) at 0700. Nine men were immersed (20 degrees C, 2 h) at 0700 and 1500 on 2 days. No differences (P > 0.05) between times were observed for metabolic heat production (M, 150 W. m(-2)), heat flow (250 W. m(-2)), mean skin temperature (T(sk), 21 degrees C), and the mean body temperature-change in M (DeltaM) relationship. Rectal temperature (T(re)) was higher (P < 0.05) before (Delta = 0.4 degrees C) and throughout CWI during 1500. The change in T(re) was greater (P < 0. 05) at 1500 (-1.4 degrees C) vs. 0700 (-1.2 degrees C), likely because of the higher T(re)-T(sk) gradient (0.3 degrees C) at 1500. These data indicate that shivering and vasoconstriction are not affected by time of day. These observations raise the possibility that CWI may increase the risk of hypothermia in the early morning because of a lower initial T(core).

Thermoregulation during cold exposure: effects of prior exercise.

This study examined whether acute exercise would impair the body's capability to maintain thermal balance during a subsequent cold exposure. Ten men rested for 2 h during a standardized cold-air test (4.6 degrees C) after two treatments: 1) 60 min of cycle exercise (Ex) at 55% peak O(2) uptake and 2) passive heating (Heat). Ex was performed during a 35 degrees C water immersion (WI), and Heat was conducted during a 38.2 degrees C WI. The duration of Heat was individually adjusted (mean = 53 min) so that rectal temperature was similar at the end of WI in both Ex (38.2 degrees C) and Heat (38.1 degrees C). During the cold-air test after Ex, relative to Heat 1) rectal temperature was lower (P < 0.05) from minutes 40-120, 2) mean weighted heat flow was higher (P < 0.05), 3) insulation was lower (P < 0.05), and 4) metabolic heat production was not different. These results suggest that prior physical exercise may predispose a person to greater heat loss and to experience a larger decline in core temperature when subsequently exposed to cold air. The combination of exercise intensity and duration studied in these experiments did not fatigue the shivering response to cold exposure.

Design of new mesogenic block molecules: formation of columnar mesophases by calamitic bolaamphiphiles with lateral lipophilic substituents.

Rigid bolaamphiphiles with lateral alkyl chains such as 1 form columnar mesophases of a novel type based on microsegregation of the three incompatible parts of the molecules (shown schematically).

[Obesity, an unresolved challenge in Chile]. / Obesidad: un desafío pendiente en Chile.

Socioeconomic and demographic changes in Chile, have modified its epidemiological profile. At the present time, the most important public health problems are non communicable chronic diseases, specially cardiovascular ailments. The prevalence of cardiovascular risk factors has also increased and obesity stands out. This review analyzes the present situation of obesity and other cardiovascular risk factors of nutritional origin, in Chile, and proposes intervention alternatives. At the present time 7% preschool children, 12% of school children, 24% of pregnant women, 10% of male adults and 24% of female adults are obese. This higher prevalence is even more pronounced in women of low socioeconomic level. Risk factors associated to obesity are an inadequate diet, with a higher consumption of fats and refined foods, sedentariness and hyperlipidemia. Primary and secondary care strategies must be devised to face this growing problem.