Growth patterns and physical plasticity in adolescent laborers

Data about the effects of working environment and excessive physical loads on human growth and constitution are insufficient. Although there are a few studies which link growth retardation in children's stature and long bones to their exposure to hard labor, it is difficult to discern whether the detrimental effects of compressive forces on growth result solely from severe compressive stresses or from the subjects' poor economic and substandard nutritional conditions as well. The aim of this study was to clarify this issue by comparing the anthropometric dimensions of laboring and non-laboring adolescents; both groups came from lower socioeconomic strata and were subject to poor living conditions. The laboring group consisted of 532 male apprentices aged 13.5-18.5, and the control group, of their 451 non-laboring peers who were attending school during the period of observation. Body weight, 3 vertical dimensions (stature, upper and lower limb lengths), 2 diameters (elbow and knee breadths), and 3 circumferences (contracted and relaxed upper arm girth and calf girth) were measured. In addition, relative growth according to the body height for each variable was computed, since relative variables are more valuable in evaluating the effects of excessive loading on the human body. The analyses showed that all vertical dimensions of laboring adolescents lagged behind those of their non-laboring peers. There were also clear differences between the two groups with regard to relative diameters and girths. The pressure effects of physical activity stimulate the transversal growth of the long bones. Similarly, circumferences, especially contracted upper arm girth relative to stature, are more developed in the laboring group than in the non-laboring group. These findings suggest that excessive workloads retard adolescents' vertical growth, especially in upper parts of the body, but that they stimulate transversal growth of the long bones and muscle development.     

武陵山区苗族儿童少年体质发育

为了探讨武陵山区苗族儿童少年体质发育特征及其规律。本文采用人体测量学的方法 , 对武陵山区苗族儿童少年17项体质发育指标进行测量, 计算11项体质指数。结果表明: 1)苗族儿童少年生长发育的各项指标均值随年龄的增长而增加; 2)苗族男女性的生长发育曲线呈上升趋势并且有交叉现象; 3)苗族男性的身高突增年龄为12-14岁, 女性则为11-13岁; 4)苗族学生的身高均值低于同龄其他民族学生; 5)苗族学生的体质指数年龄变化规律与其他民族基本相似, 但身体各部分的发育程度不相同; 6)苗族学生的维尔维克指数均值高于同龄马山壮族学生。研究显示苗族儿童少年体质发育符合一般生长发育规律, 并有性别差异, 苗族男女生的体质发育相对落后于汉族等其他民族。     

Sleep patterns of day-working, evening high-schooled adolescents of São Paulo, Brazil

Children who grow up in developing countries of the world must work to help financially support their families, and they must also attend school. We investigated the impact of work on the sleep of working vs. nonworking high school students. Twenty-seven S?o Paulo, Brazil, public high school students (eight male and eight female working students plus six nonworking female and five nonworking male students) 14-18 yrs of age who attended school Monday-Friday between 19:00 to 22:30h participated. A comprehensive questionnaire about work and living conditions, health status, and diseases and their symptoms was also answered. The activity level and rest pattern (sleep at night and napping during the day) were continuously assessed by wrist actigraphy (Ambulatory Monitoring, USA). The main variables were analyzed by a two-factor ANOVA with application of the Tukey HSD test for multiple comparisons, and the length of sleep during weekdays vs. weekends was compared by Student t-test. Working students went to sleep earlier weekends [F(1,23)=6.1; p=0.02] and woke up earlier work days than nonworking students [F(1,23) = 17.3; p = 0.001]. The length of nighttime sleep during weekdays was shorter among all the working [F(1,23)= 16.7; p <0.001] than all the nonworking students. The sleep duration of boys was shorter than of girls during weekends [F(1,23)= 10.8; p <0.001]. During weekdays, the duration of napping by working and nonworking male students was shorter than nonworking female students. During weekdays working girls took the shortest naps [F(1,23)= 5.6; p = 0.03]. The most commonly reported sleep complaint during weekdays was difficulty waking up in the morning [F(1,23) = 6.5; p = 0.02]. During weekdays, the self-perceived sleep quality of working students was worse than nonworking students [F(1,23) = 6.2; p = 0.02]. The findings of this study show that work has negative effects on the sleep of adolescents, with the possible build-up of a chronic sleep debt with potential consequent impact on quality of life and school learning.     

遗传和环境因素对儿童青少年身体高度及其比例的影响

目前有关儿童青少年坐高、下肢长及其比值的报道多为非双生子人群的研究。为了解遗传和环境因素对儿童青少年坐高、下肢长及坐高与下肢长比值影响的相对大小,我们对796对6～18岁双生子的身高和坐高进行了测量,计算下肢长及坐高与下肢长比值,采用结构方程模型分析其遗传和环境相对效应。结果发现,校正年龄后,男女15～18岁年龄组坐高和下肢长的遗传度(0.63～0.78)均分别高于同性别低年龄段儿童青少年(0.31～0.68);坐高与下肢长比值的遗传度除9～11岁女生(0.84)外,其他年龄组均较低(男0.16～0.46,女0.21～0.57);共同环境因素和特殊环境因素对6～14岁儿童青少年各指标的作用较大。本研究提示,在快速发育时期,坐高、下肢长和坐高与下肢长比值对环境因素更为敏感,遗传度较低;机体越成熟,其遗传效应更强。     

Morphofunctional development of Tyvan and Russian schoolchildren

The specific features of the physical development and functional capacity of the cardiorespiratory system of young schoolchildren living in the Republic of Tyva (formerly, Tuva) as dependent on the sex, ethnicity, and social conditions were studied. Acceleration processes in the physical development of Tyvan children aged 8–11 years during the past 35 years were identified. It was shown that morphological adaptation to climatic conditions was more obvious in schoolchildren of both ethnic groups living in the countryside as compared to those in urban areas: they had a smaller total body size, stronger physique, and better developed chest. Analysis of the functional capacity of the cardiorespiratory system showed that Tyvan children had higher reserves of the cardiorespiratory system as estimated by the vital index, pulmonary capacity, stroke volume, and cardiac output than Russian children of the same age. Sex-dependent differences in the morphofunctional development of children of both ethnic groups become evident beginning from the age of nine years.     

The physiological state of suspension cultured cells affects the expression of the β-glucuronidase gene following transformation of tall fescue (Festuca arundinacea) protoplasts

Both the stage of the growth cycle and the age of the cell culture used to isolate protoplasts had a pronounced effect on both transient and stable expression of the GUS gene. A level of GUS gene transient expression of 9000 pmol 4MU/μg protein/h and a frequency of GUS gene stable expression of 5.72% were obtained with protoplasts isolated from suspension cultures 10–20 weeks after initiation and 3–4 days after subculturing when an optimized transformation protocol and a rice actin 1 promoter-uidA gene construct were used. The effect of the cell growth cycle on GUS gene transient expression was closely correlated with the growth rate and the rate of protein synthesis in cell cultures whereas prolonged subculturing of the cells resulted in a gradual decline in both transient and stable expression. The length of time cells were digested in cell wall digestion enzyme and the osmolarity of the transformation medium were found to critically affect both the level of transient and stable GUS gene expression. The composition and osmolarity of the protoplast culture medium was less critical for transient GUS gene expression although the osmolarity of the medium was shown to have a significant effect on stable expression of the GUS gene.     

Sleep Patterns of Day-Working,Evening High-Schooled Adolescents of São Paulo,Brazil

Children who grow up in developing countries of the world must work to help financially support their families, and they must also attend school. We investigated the impact of work on the sleep of working vs. nonworking high school students. Twenty-seven São Paulo, Brazil, public high school students (eight male and eight female working students plus six nonworking female and five nonworking male students) 14–18 yrs of age who attended school Monday–Friday between 19:00 to 22:30 h participated. A comprehensive questionnaire about work and living conditions, health status, and diseases and their symptoms was also answered. The activity level and rest pattern (sleep at night and napping during the day) were continuously assessed by wrist actigraphy (Ambulatory Monitoring, USA). The main variables were analyzed by a two-factor ANOVA with application of the Tukey HSD test for multiple comparisons, and the length of sleep during weekdays vs. weekends was compared by Student t-test. Working students went to sleep earlier weekends [F_(1,23) = 6.1; p = 0.02] and woke up earlier work days than nonworking students [F_(1,23) = 17.3; p = 0.001]. The length of nighttime sleep during weekdays was shorter among all the working [F_(1,23) = 16.7; p < 0.001] than all the nonworking students. The sleep duration of boys was shorter than of girls during weekends [F_(1,23) = 10.8; p < 0.001]. During weekdays, the duration of napping by working and nonworking male students was shorter than nonworking female students. During weekdays, working girls took the shortest naps [F_(1,23) = 5.6; p = 0.03]. The most commonly reported sleep complaint during weekdays was difficulty waking up in the morning [F_(1,23) = 6.5; p = 0.02]. During weekdays, the self-perceived sleep quality of working students was worse than nonworking students [F_(1,23) = 6.2; p = 0.02]. The findings of this study show that work has negative effects on the sleep of adolescents, with the possible build-up of a chronic sleep debt with potential consequent impact on quality of life and school learning.     

Seroprevalence and severity of 2009 pandemic influenza A H1N1 in Taiwan

Background

This study is to determine the seroprevalence of the pandemic influenza A H1N1 virus (pH1N1) in Taiwan before and after the 2009 pandemic, and to estimate the relative severity of pH1N1 infections among different age groups.

Methodology/Principal Findings

A total of 1544 and 1558 random serum samples were collected from the general population in Taiwan in 2007 and 2010, respectively. Seropositivity was defined by a hemagglutination inhibition titer to pH1N1 (A/Taiwan/126/09) ≥1:40. The seropositivity rate of pH1N1 among the unvaccinated subjects and national surveillance data were used to compare the proportion of infections that led to severe diseases and fatalities among different age groups. The overall seroprevalence of pH1N1 was 0.91% (95% confidence interval [CI] 0.43–1.38) in 2007 and significantly increased to 29.9% (95% CI 27.6–32.2) in 2010 (p<0.0001), with the peak attack rate (55.4%) in 10–17 year-old adolescents, the lowest in elderly ≥65 years (14.1%). The overall attack rates were 20.6% (188/912) in unvaccinated subjects. Among the unvaccinated but infected populations, the estimated attack rates of severe cases per 100,000 infections were significantly higher in children aged 0–5 years (54.9 cases, odds ratio [OR] 4.23, 95% CI 3.04–5.90) and elderly ≥ 65years (22.4 cases, OR 2.76, 95% CI 1.99–3.83) compared to adolescents aged 10–17 years (13.0 cases). The overall case-fatality rate was 0.98 per 100,000 infections without a significant difference in different age groups.

Conclusions/Significance

Pre-existing immunity against pH1N1 was rarely identified in Taiwanese at any age in 2007. Young children and elderly – the two most lower seroprotection groups showed the greatest vulnerability to clinical severity after the pH1N1 infections. These results imply that both age groups should have higher priority for immunization in the coming flu season.     

Characteristics of the Morphofunctional Development of 7- to 14-Year-Old Boys with Different Types of Adaptive Response

The parameters of physical development, the cardiorespiratory system, and the physical working capacity were studied in 275 boys aged 7–14 years. The type of adaptive response—sprinter or stayer—was assessed from the adaptive response of the neuromuscular apparatus to physical exercise. The morphofunctional development of children and adolescents was shown to be correlated with the type of adaptive response. The significant differences in many anthropometric and functional indicators revealed between boys of different types provide a background for optimizing the physical and sporting activity of schoolchildren.     

Influence of magnesium ions on heat shock and ethanol stress responses of Saccharomyces cerevisiae

This study has highlighted the role of magnesium ions in the amelioration of the detrimental effects of ethanol toxicity and temperature shock in a winemaking strain of Saccharomyces cerevisiae. Specifically, results based on measurements of cellular viability and heat shock protein synthesis together with scanning electron microscopy have shown that, by increasing the bioavailability of magnesium ions, physiological protection is conferred on yeast cells. Elevating magnesium levels in the growth medium from 2 to 20 mM results in repression of certain heat shock proteins following a typical heat shock regime (30–42°C shift). Seed inocula cultures prepropagated in elevated levels of magnesium (i.e. ‘preconditioned’) also conferred thermotolerance on cells and repressed the biosynthesis of heat shock proteins. Similar results were observed in response to ethanol stress. Extra- and intracellular magnesium may both act in the physiological stress protection of yeast cells and this approach offers potential benefits in alcoholic fermentation processes. The working hypothesis based on our findings is that magnesium protects yeast cells by preventing increases in cell membrane permeability elicited by ethanol and temperature-induced stress.     

Survival of HIV-infected adolescents on antiretroviral therapy in Uganda: findings from a nationally representative cohort in Uganda

Background

Adolescents have been identified as a high-risk group for poor adherence to and defaulting from combination antiretroviral therapy (cART) care. However, data on outcomes for adolescents on cART in resource-limited settings remain scarce.

Methods

We developed an observational study of patients who started cART at The AIDS Service Organization (TASO) in Uganda between 2004 and 2009. Age was stratified into three groups: children (≤10 years), adolescents (11–19 years), and adults (≥20 years). Kaplan-Meier survival curves were generated to describe time to mortality and loss to follow-up, and Cox regression used to model associations between age and mortality and loss to follow-up. To address loss to follow up, we applied a weighted analysis that assumes 50% of lost patients had died.

Findings

A total of 23,367 patients were included in this analysis, including 810 (3.5%) children, 575 (2.5%) adolescents, and 21 982 (94.0%) adults. A lower percentage of children (5.4%) died during their cART treatment compared to adolescents (8.5%) and adults (10%). After adjusting for confounding, other features predicted mortality than age alone. Mortality was higher among males (p<0.001), patients with a low initial CD4 cell count (p<0.001), patients with advanced WHO clinical disease stage (p<0.001), and shorter duration of time receiving cART (p<0.001). The crude mortality rate was lower for children (22.8 per 1000 person-years; 95% CI: 16.1, 29.5), than adolescents (36.5 per 1000 person-years; 95% CI: 26.3, 46.8) and adults (37.5 per 1000 person-years; 95% CI: 35.9, 39.1).

Interpretation

This study is the largest assessment of adolescents receiving cART in Africa. Adolescents did not have cART mortality outcomes different from adults or children.     

Impact of war on growth patterns in school children in Croatia

The objective of this paper is to present the growth patterns of school children in Osijek--the city which was exposed to severe attacks during the aggression on Croatia. The mean height and weight of Osijek schoolchildren aged 7 to 18 and the menarcheal age in girls in academic year 1995/96 were compared to the analogous data collected in 1980/81. The secular changes in height were heterogeneous. In older age groups from 12 in girls and 13 in boys, the mean height in 1995/96 increased markedly, whereas from 9 to 11 or 12, changes were undulating. In the youngest groups--at the age of 7 in both genders, and at 8 in boys, negative changes were observed. Markedly smaller height in this cohort was still pronounced in 1999/2000 when these children reached the age of 11. However, one year later (2000/01), at the age of 12, boys and girls caught up with their peers in the previous generations. These children during the war were approximately at the age of 2.5 to 4, a period when growth patterns are highly sensitive to adverse environmental influences. It might be possible that the emotional stress caused by a change of environment and separation from home, contributed to the deceleration of growth rate, i.e. the smaller height in a large part of childhood.     

Prevalence and predictors of vitamin D insufficiency in children: a Great Britain population based study

ObjectivesTo evaluate the prevalence and predictors of vitamin D insufficiency (VDI) in children In Great Britain.DesignA nationally representative cross-sectional study survey of children (1102) aged 4–18 years (999 white, 570 male) living in private households (January 1997–1998). Interventions provided information about dietary habits, physical activity, socio-demographics, and blood sample. Outcome measures were vitamin D insufficiency (<50 nmol/L).ResultsVitamin D levels (mean = 62.1 nmol/L, 95%CI 60.4–63.7) were insufficient in 35%, and decreased with age in both sexes (p<0.001). Young People living between 53–59 degrees latitude had lower levels (compared with 50–53 degrees, p = 0.045). Dietary intake and gender had no effect on vitamin D status. A logistic regression model showed increased risk of VDI in the following: adolescents (14–18 years old), odds ratio (OR) = 3.6 (95%CI 1.8–7.2) compared with younger children (4–8 years); non white children (OR = 37 [95%CI 15–90]); blood levels taken December-May (OR = 6.5 [95%CI 4.3–10.1]); on income support (OR = 2.2 [95%CI 1.3–3.9]); not taking vitamin D supplementation (OR = 3.7 [95%CI 1.4–9.8]); being overweight (OR 1.6 [95%CI 1.0–2.5]); <1/2 hour outdoor exercise/day/week (OR = 1.5 [95%CI 1.0–2.3]); watched >2.5 hours of TV/day/week (OR = 1.6[95%CI 1.0–2.4]).ConclusionWe confirm a previously under-recognised risk of VDI in adolescents. The marked higher risk for VDI in non-white children suggests they should be targeted in any preventative strategies. The association of higher risk of VDI among children who exercised less outdoors, watched more TV and were overweight highlights potentially modifiable risk factors. Clearer guidelines and an increased awareness especially in adolescents are needed, as there are no recommendations for vitamin D supplementation in older children.     

Actividad física,condición física y sobrepeso en niños y adolescentes: evidencia procedente de estudios epidemiológicos

Physical activity and fitness play a significant role in prevention of overweight and obesity in children and adolescentes. Current understanding and evidence from epidemiologic studies provide useful insights to better understand how they relate to each other and how to develop future intervention strategies. This paper summarizes the most relevant information from cross-sectional and longitudinal studies on the relationships between physical activity, physical fitness, and overweight in early life. According to current scientific evidence: (i) High levels of physical activity during childhood and adolescence, particularly vigorous physical activity, are associated to lower total and central adiposity at this age and later in life; (ii) the level of physical fitness, especially aerobic fitness, is inversely related to current and future adiposity levels; (iii) overweight children and adolescents with a high fitness level have a healthier cardiovascular profile than their overweight, low fit peers and a similar profile to their normal weight, low fit peers. This suggests that high fitness levels may counteract the negative consequences attributed to body fat. These findings suggest that increasing physical fitness in overweight children and adolescentes may have many positive effects on health, including lower body fat levels.     

Differences in the coordination of agonist and antagonist muscle groups in below-knee amputee and able-bodied children during dynamic exercise

A lack of co-contraction may predispose to knee instability or laxity, resulting in additional shear stress on the internal structures of the knee, especially in below-knee amputee (BKA) subjects. The purposes of this study were: (1) to provide information on how BKA children regulate agonist and antagonist muscle coordination, and (2) to quantify the level of knee co-contraction in able-bodied (AB) and BKA children during the stepping-in-place (SIP) task. Fourteen children (7 BKA vs. 7 AB), paired for age, weight and height, participated in this study. One-way ANOVA with Newman–Keuls post hoc tests (p < 0.05) were used to compare peak power, the co-contraction index, and the resultant agonist and antagonist moments during different phases of SIP. Statistical analysis revealed that BKA children perform the task with similar kinematics than AB children while they generated less co-contraction in both their non-amputated limb and amputated limb, notably because the two groups of children used different agonist and antagonist muscles during the same periods of the SIP. This lack of co-contraction may reduce knee stability and may stress the internal structures of the knee in both the NAL and AL, and may lead to the development of premature knee osteoarthritis.     

达斡尔族中小学生体质发育现状及20多年来的变化

本文报道了6~18岁1993名达斡尔族学生8项体质指标(身高、坐高、体重、肩宽、骨盆宽、胸围、腰围和臀围)的测量结果,并计算了10项体质指数。结果发现,达斡尔族在我国属体质发育较高的民族,并表现为一定的城乡差异;20多年来达斡尔族学生身高、体重、胸围全面增长,男女生身高最大增长年龄均提前约1岁左右,男生高年龄组身高和身体充实度增幅较大,但女生变化不大且肩宽和骨盆宽呈下降趋势。提示达斡尔族青少年体质发育表现为以生长突增提前为主的生长长期趋势,但女生高年龄组身高增长不明显、身体充实度有待提高,应采取营养和锻炼等措施促进其生长发育水平全面提高。     

Reference intervals for the echocardiographic measurements of the right heart in children and adolescents: a systematic review

Background

Transthoracic echocardiography is the primary imaging modality for the diagnosis of right ventricular (RV) involvement in congenital and acquired heart diseases. There is increasing recognition of the contribution of RV dysfunction in heart diseases affecting children and adolescents, but there is insufficient information on reference intervals for the echocardiographic measurements of the right heart in children and adolescents that represent all the continental populations of the world.

Objective

The aim of this systematic review was to collate, from published studies, normative data for echocardiographic evaluation of the right heart in children and adolescents, and to identify gaps in knowledge in this field especially with respect to sub-Saharan Africans.

Methods

We performed a systematic literature search to identify studies of reference intervals for right heart measurements as determined by transthoracic echocardiography in healthy children and adolescents of school-going age. Articles were retrieved from electronic databases with a combination of search terms from the earliest date available until May 2013.

Results

Reference data were available for a broad range of variables. Fifty one studies out of 3096 publications were included. The sample sizes of the reference populations ranged from 13 to 2036 with ages varying from 5 to 21 years. We identified areas lacking sufficient reference data. These included reference data for determining right atrial size, tricuspid valve area, RV dimensions and areas, the RV % fractional area change, pulmonary artery pressure gradients and the right-sided haemodynamics, including the inferior vena cava dimensions and collapsibility. There were no data for sub-Saharan African children and adolescents.

Conclusion

Reliable reference data are lacking for important echocardiographic measurements of the RV in children and adolescents, especially for sub-Saharan Africans.