A longitudinal analysis of sex differences in bone mineral accrual in healthy 8-19-year-old boys and girls

Background: Although early in life there is little discernible difference in bone mass between boys and girls, at puberty sex differences are observed. It is uncertain if these differences represent differences in bone mass or just differences in anthropometric dimensions. Aim: The study aimed to identify whether sex independently affects bone mineral content (BMC) accrual in growing boys and girls. Three sites are investigated: total body (TB), femoral neck (FN) and lumbar spine (LS). Subjects and methods: 85 boys and 67 girls were assessed annually for seven consecutive years. BMC was assessed by dual energy X-ray absorptiometry (DXA). Biological age was defined as years from age at peak height velocity (PHV). Data were analysed using a hierarchical (random effects) modelling approach. Results: When biological age, body size and body composition were controlled, boys had statistically significantly higher TB and FN BMC at all maturity levels (p < 0.05). No independent sex differences were found at the LS (p > 0.05). Conclusion: Although a statistical significant sex effect is observed, it is less than the error of the measurement, and thus sex difference are debatable. In general, sex difference are explained by anthropometric difference.     

Somatotype related to centripetal fat patterning of 8- to 19-year-old Basque boys and girls

The association between fat distribution and Heath-Carter anthropometric somatotypes was studied in a sample of Basque children and youth aged 8–19 years. About mid-adolescence, mean somatotype of Basque males changed, diminishing in endomorphy and mesomorphy, and increasing slightly in ectomorphy. For the same period, reduced mesomorphy was the most striking change in the female mean somatotype; meanwhile, there was an increase in endomorphy and a decrease in ectomorphy. Two groups of fat distribution were identified: centripetal and peripheral. Centripetal fat increased with age in both sexes. Fat distribution groups showed the following characteristics: a) mean somatotypes of centripetal and peripheral subjects were significantly different; b) centripetal boys and girls were extreme endomorphs prior to adolescent somatotype change; c) centripetal girls showed high ratings of endomorphy after adolescence; d) mesomorphy was related to a centripetal fat distribution pattern in both sexes; e) using the BMI as a criterion of obesity, only 16.3% of centripetal males and 21.8% of centripetal females were classified as obese; f) obesity was absent among subjects with a peripheral pattern, except for one male showing an endomorphic-mesomorph somatotype; h) the obese showed extreme somatotypes with high endomorphy and mesomorphy, and minimal ectomorphy. © 1994 Wiley-Liss, Inc.     

Patterns of TW-1 and TW-2 skeletal age differences in 12-19-year-old Belgian boys

The pattern of differences between TW-1 and TW-2 skeletal ages was investigated in a mixed longitudinal sample of Belgian school boys aged about 12-19 years. The differences between the TW-1 and TW-2 skeletal ages decrease from 12 years until 15 years, then increase until they stabilize at 17 years. TW-1 skeletal ages are greater than TW-2 skeletal ages, except at 14 and 15 years. This trend confirms the findings in better-off black and white Philadelphia children and in disadvantaged Mexican children (Malina and Little 1981).     

Sex differences in FSH-regulatory peptides in pubertal age boys and girls and effects of sex steroid treatment

BACKGROUND: FSH concentrations are higher in girls than in boys before puberty. We hypothesized that steroid-mediated changes in FSH-regulatory proteins underlie the sex differences in FSH secretion and pubertal timing. METHODS: FSH-regulatory proteins, LH, FSH and sex steroids were measured in five boys, 10 girls, and five girls with Turner syndrome before and during sex steroid treatment (girls, 0.05 mg/day estradiol; boys, 5 mg/day testosterone) for up to 4 weeks. Blood was obtained every 15 min from 20.00 to 08.00 h before and during sex steroid treatment. RESULTS: The mean FSH concentration was higher in girls than in boys (P = 0.0044). Activin-A concentrations were greater (P < 0.0001) and inhibin-B concentrations lower (P < 0.0001) in girls compared with boys. Steroid treatment (i) suppressed LH/FSH concentrations in all subjects; (ii) increased the mean activin-A concentration in all but the Turner girls (P = 0.001); and (iii) decreased inhibin-B concentrations in boys (P = 0.005) but not in girls. Total follistatin and follistatin 288 concentrations did not differ by sex. CONCLUSIONS: Sex steroids regulate circulating activin-A and inhibin-B concentrations in children. The lower inhibin-B and higher activin-A concentrations may explain the higher FSH and earlier onset of puberty in girls.     

Psychophysiology of spider phobia in 8- to 12-year-old girls

The present investigation focused on late event-related potentials (ERPs) and facial electromyographic (EMG) activity in response to symptom provocation in 8- to 12-year-old spider phobic girls and compared results to those in non-fearful controls. Fourteen patients and 14 controls were presented with phobia-relevant, generally fear-inducing, disgust-inducing and affectively neutral pictures in an EEG/EMG session. ERPs were extracted in the time-windows 340-500 ms (P300) and 550-770 ms (late positive potential, LPP). Relative to controls, phobics showed enhanced amplitudes of P300 and LPP in response to spider pictures. This result is interpreted to reflect motivated attention to emotionally salient stimuli. Moreover, phobics showed enhanced average facial EMG activity of the levator labii and the corrugator supercilii in response to spider pictures, reflecting the negative valence and disgust relevance of spiders. Additionally, spider phobic girls relative to controls showed higher overall disgust proneness and heightened average facial EMG activity in both muscle regions in response to disgust stimuli, possibly revealing a disgust-based origin of spider phobia in children. These aspects should be considered in psychotherapeutic treatment of childhood spider phobia.     

Spectral and bout detection analysis of physical activity patterns in healthy,prepubertal boys and girls

Little is known about the frequency-intensity patterns of naturally occurring physical activity in children. A data set obtained previously by direct observation of physical activity in 8 girls and 7 boys (all prepubertal, ages 6–10) was analyzed with spectral analysis to detect significant frequency-intensity relationships. Pulse detection algorithms were used to characterize the number of exercise bouts, their duration and relative intensity. Spectral analysis revealed that physical activity bouts were frequent, pulsatile, and random with no significant frequencies detected during many 24-min periods of observation. An average of 83 ± 11 bouts per hour were observed in boys and 89 ± 12 bouts per hour in girls, and the mean duration of an exercise bout was 21 ± 5 sec for boys and 20 ± 4 sec for girls (NS). While high-intensity exercise bouts comprised less than 20% of the time spent in physical activity, duration of high intensity exercise bouts tended to be longer and accounted for about 40% of the energy expenditure associated with physical activity. Spontaneous physical activity in prepubertal children is characterized by frequent bouts of brief, mostly low intensity exercise, randomly interspersed with less frequent, but metabolically substantial high intensity bouts. These findings are potentially useful in assessing the impact of disease on quality of life in children, investigating the relationship between physical activity and mechanisms of growth and development, and creating new approaches for in-laboratory exercise testing in children. Am. J. Hum. Biol. 10:289–297, 1998. © 1998 Wiley-Liss, Inc.     

Pubertal development in Caracas upper-middle-class boys and girls in a longitudinal context

Changes between pubertal stages (PS) are best analyzed in a longitudinal context. A sample of 67 boys and 48 girls from the Caracas Longitudinal Study who presented data for the full range of pubertal development: genitalia (G2–G5), breast (B2–B5), pubic hair (PH2–PH5), axillary hair (AH2–AH3), and age at menarche (AM) during follow-up, were assessed at clinical examination. Medians and standard errors for ages at each stage were estimated with the logit method. For length of intervals between stages of genitalia, breast, pubic hair and axillary hair, intervals B2–M and PH2–M, survival analysis was used according to life tables and Cox regression analysis. In boys, G2 occurred at 11.61 years; in girls, B2 occurred at 10.35 years and AM at 12.55 years of age. In both sexes, length of the intervals PS 2–3 and 3–4 were approximately 1 year, while PS 4–5 was 1.5 years. Duration of puberty reached 3.7 years in boys (G2–G5) and 3.3 years in girls (B2–B5); corresponding intervals for PH2–PH5 were 3.1 and 3.0 years in boys and girls, respectively. B2–AM was 1.8 years (with a range of 0.3–3.6 years) and PH2–AM was 1.5 years (with a range 0.3–3.5 years). These results are useful for screening and monitoring: identifying abnormal pubertal patterns in subjects who are advanced or delayed with respect to their peers, together with other pubertal events such as age at peak height and weight velocity and skeletal age. Am. J. Hum. Biol. 12:88–96, 2000. © 2000 Wiley-Liss, Inc.     

Relative importance of lean and fat mass on bone mineral density in a group of adolescent girls and boys

The aim of this study was to determine the relative importance of lean mass (LM) and fat mass (FM) on bone mineral density (BMD) in a group of adolescent girls and boys. A total of 65 adolescent boys and 35 adolescent girls participated in this study. Whole body (WB) and lumbar spine (L1–L4) BMD were measured by dual-energy X-ray absorptiometry (DXA). Body composition was assessed using the same technique. In boys, LM was strongly related to WBBMD (r = 0.68; p < 0.001) and to L1–L4 BMD (r = 0.61; p < 0.001), whereas FM was not positively related to BMD and was negatively associated with WB bone mineral apparent density (WBBMAD). In girls, both LM and FM were positively related to WBBMD (r = 0.41; p < 0.05 and r = 0.49; p < 0.01, respectively), whereas only FM was correlated to L1–L4 BMD (r = 0.33; p < 0.05). Finally, in a multiple regression analysis, FM was found to be a better positive determinant of WBBMD than LM in girls, whereas in boys, FM was found to be a negative determinant of WBBMD and L1–L4 BMD. This study suggests that LM is a strong determinant of WBBMD and L1–L4 BMD in boys, and that FM is a stronger determinant of WBBMD than LM in girls.     

Variation in bone mineral density in adults in Poland: age and sex differences

The decline of mineral bone density with age can lead in more extreme cases to osteopenia and osteoporosis, and is therefore one of the aspects of ageing with great medical and social significance. With this idea in mind a study of age changes in the trabecular and, separately, the cortical bone density of the radius was carried out in 1218 females and 405 males, aged 22 to 60 years, all occupationally active inhabitants of the city of Wroclaw, Poland. The technique used was the peripheral Quantitative Computed Tomography (pQCT). It was found that in females bone densities remain relatively stable throughout the period between 22 and 40 years. They then begin to decline slowly, with a rapid decline after the age of 55. A distinctly different pattern was found among males, with bone densities reaching peak values, markedly higher than those in females, in the third decade of life. After this age the bone density values begin to decline at a rapid rate, so that by the age of 60 years mean trabecular and cortical densities in males have decreased to levels almost equivalent to females of equal age. In view of the small size of the male samples, especially in the older age classes, the above results should be treated with caution and confirmed using larger samples.     

Variation in bone mineral density in adults in Poland: age and sex differences

The decline of mineral bone density with age can lead in more extreme cases to osteopenia and osteoporosis, and is therefore one of the aspects of ageing with great medical and social significance. With this idea in mind a study of age changes in the trabecular and, separately, the cortical bone density of the radius was carried out in 1218 females and 405 males, aged 22 to 60 years, all occupationally active inhabitants of the city of Wroclaw, Poland. The technique used was the peripheral Quantitative Computed Tomography (pQCT). It was found that in females bone densities remain relatively stable throughout the period between 22 and 40 years. They then begin to decline slowly, with a rapid decline after the age of 55. A distinctly different pattern was found among males, with bone densities reaching peak values, markedly higher than those in females, in the third decade of life. After this age the bone density values begin to decline at a rapid rate, so that by the age of 60 years mean trabecular and cortical densities in males have decreased to levels almost equivalent to females of equal age. In view of the small size of the male samples, especially in the older age classes, the above results should be treated with caution and confirmed using larger samples.     

Physical activity in relation to aerobic fitness and body fat in 14- to 15-year-old boys and girls

The purpose of this study was to examine the strength of the relationship between different variables of physical activity and aerobic fitness and body fat in adolescent boys and girls. Activity energy expenditure (AEE), time spent in a sedentary state, and time spent engaged in moderate and vigorous physical activity (MVPA, ≥50% peak oxygen uptake, ) were assessed by the minute-by-minute heart rate monitoring method in 82 randomly selected 14- to 15-year olds (42 boys, 40 girls). Body fat was determined by measuring skinfold thicknesses. was measured by indirect calorimetry. Somatic maturity level was determined by percentages of adult (i.e. 18 years) height attained at examination. AEE was related to aerobic fitness for both genders (boys, r=0.30, P=0.056; girls, r=0.45, P=0.003). For boys, there was a significant relationship between maturity level and (r=0.48, P<0.001). For both genders, body fat was significantly and negatively related to (r=–0.48 and r=–0.43, P<0.01). Body fat and maturity explained 47% of the variation in in boys, whereas AEE and body fat explained 22% of the variation in in girls. No significant associations between physical activity variables and the data on body fat were observed. The total amount of physical activity (AEE) was related to , at least in adolescent girls. Although seems to be influenced by the maturity level in adolescent boys, the data support the promotion of a daily active lifestyle among young people. Electronic Publication     

A longitudinal study of the effect of voicing on the dichotic listening ear advantage in boys and girls at age 5 to 8

Recent studies indicate that the effect of voicing on the ear advantage in dichotic listening might serve as indicator of the development of speech processing abilities in children. In the present longitudinal study, we tested this idea by applying dichotic listening with voiced and unvoiced consonant-vowel syllables. In 35 boys and girls, tested at the age of 5, 6, 7, and 8 years, we found that the effect of voicing increases with age, and that girls were more affected by the voicing characteristics than boys. These results indicate a sex difference in the development of speech processing abilities.     

A 12-month treatment with tenofovir does not impair bone mineral accrual in HIV-infected children

BACKGROUND: Short-term use of tenofovir (TDF) has been associated with bone mineral loss in adults and children. OBJECTIVE: To assess whether the substitution of stavudine with TDF would result in decreased bone mineral content (BMC) and bone mineral density (BMD) accrual in HIV-infected children. METHODS: The lumbar spine and whole-body BMC and BMD were measured by dual-energy x-ray absorptiometry in 16 HIV-infected children (age range: 6.4-17.9 years) on stable highly active antiretroviral therapy. Bone measurements were obtained 12 months before the switch, at baseline, and 12 months after switching to TDF. Expected changes in bone measurements were calculated from cross-sectional data obtained from 166 healthy children. RESULTS: The BMC and BMD increments observed before switching therapy did not differ from expected increments. Similarly, the changes detected during treatment with TDF did not differ significantly from those calculated in healthy controls. CONCLUSIONS: Substitution to a TDF-containing antiretroviral regimen does not seem to impair bone mineral accrual in children showing a good immunologic response to antiretroviral treatment.     

Mixed‐longitudinal growth of Karimojong girls and boys in Moroto District,Uganda

In this article we examine results of a mixed‐longitudinal study of child and adolescent growth among agropastoral Karimojong children in Moroto District, northeast Uganda. During a 5‐month period from August to December, 2004, longitudinal data were collected for a mixed sample of 104 Karimojong children, aged from birth to 18 years. During a previous study in 1998–1999,we had measured 26 of these children who then ranged in Age between 3 months and 7 years. Most of the children were small and thin relative to accepted growth standards, and prevalence of stunting and wasting in childhood was high. In the period from the end of childhood through adolescence, however, Karimojong girls showed marked variability in annual growth, with some attaining a large adult size relative to what we predicted based on their poor childhood growth. Developmental, evolutionary, and environmental determinants are considered. We conclude that growth of these children reflects exposure to environmental insults that vary unpredictably within relatively short intervals. Variability in the magnitude and timing of these insults among children from different birth‐cohorts is probably sufficient to account for so‐called “shifting” of growth percentiles in childhood and adolescence in this mixed sample. Am. J. Hum. Biol., 2009. © 2008 Wiley‐Liss, Inc.     

健康绝经妇女体成分差异对跟骨骨密度的影响

目的探讨锦州市健康绝经妇女身体质量指数(BMI)、左下肢肌肉含量及脂肪含量等身体组成成分与左侧跟骨骨密度(BMD)的关系。方法使用体成分仪及骨密度仪测量421例健康绝经妇女的体成分和左侧跟骨骨密度。结论左侧跟骨BMD与年龄呈负相关,与左下肢肌肉量、BMI呈正相关关系,而与左下肢脂肪量没有相关性。结论 BMI是影响绝经妇女BMD的重要因素,加强运动、增加身体肌肉含量对预防骨质疏松有重要作用。     

Changes in adiposity status from childhood to adolescence: A 6-year longitudinal study in Portuguese boys and girls

Background: Cross-sectional data show high prevalence of overweight in Portuguese children, but there are few longitudinal studies describing the patterns of obesity development in the young.

Aim: To examine the trajectories of obesity from late childhood to adolescence.

Subjects and methods: Triceps and subscapular skinfold thickness measurements were carried out in 288 children at age 9 (baseline) and later at age 15 (follow-up). Percentage body fat (%BF) was estimated according to Slaughter equations and the health-related definition of obesity ( ≥ 25%BF in boys and ≥ 30%BF in girls) was used.

Results: In boys, the prevalence of obesity decreased from 21.9% to 14.8% (p < 0.05) while in girls it increased from 14.3% to 19.5%. The incidence of obesity in the 6-year study period was 2.6% and 8.3% for boys and girls, respectively (p < 0.05). In comparison with girls, the percentage of boys that reversed obesity was more than 3-fold higher (3% vs 9.7%, p < 0.05). Obesity tracked moderately in both sexes (Kappa = 0.6, p < 0.001).

Conclusion: The results indicate a marked sex difference in the incidence and reversal of obesity from late childhood to adolescence that is unfavourable to girls. Consideration of this difference might be important when designing programmes for the prevention and treatment of obesity focusing on this period.     

Morbidity in early childhood: differences between girls and boys under 10 years old.

The aim of the study was to investigate the differences in presented morbidity and use of health services among boys and girls in early childhood. The study was performed using data collected by the continuous morbidity registration project of the department of general practice at Nijmegen University. All recorded morbidity, referrals to specialists and admissions to hospitals were recorded by the registration project. The study population included children born in four practices from 1971 to 1984. The children were followed up until the age of five years and if possible until the age of 10 years. The morbidity of the children had been categorized into three levels of seriousness of diagnosis and 15 diagnostic groups as part of the registration project. Boys presented more morbidity than girls in the first years of their lives. For the age group 0-4 years this was true for all levels of seriousness of diagnosis except the most serious. In this younger age group significantly more boys than girls suffered respiratory diseases, behaviour disorders, gastroenteritis and accidents. Girls suffered from more episodes of urinary infection than boys in both age groups. More boys were referred to specialists and admitted to hospital than girls. The findings of this study suggest that not only inborn factors can explain the sex differences in presented morbidity and use of health services in early childhood. In particular, differences between girls and boys in terms of non-serious morbidity and referral and admission rates suggest a different way of handling health problems in boys and girls in early childhood both by parents and doctors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Seasonal height velocity variation in boys and girls 8–18 years

This study investigated the seasonal variation in height velocity during the summer and winter months. The subjects were healthy children, 109 boys and 119 girls, 8.5–18.0 years of age who are part of an ongoing longitudinal study of bone mineral accrual. Anthropometric dimensions were taken twice a year, in the fall in conjunction with the annual bone assessment measures and 6 months later. Six-month velocities for height were calculated, which produced 982 velocities in boys and 1043 velocities in girls. Over the age range studied, summer velocities accounted for at least 67% of the total yearly growth in boys and 60% of the total yearly growth in girls. Separate two-way ANOVAs (season by age) were used to compare the summer and winter velocities over half-yearly age increments in both sexes. Season and age effects were significant (P < 0.01), but the interaction effect was not significant. The seasonal differences converged in the later years when the summer and winter velocities decreased to zero. The results demonstrate the importance of considering seasonal variation in height velocity in designing studies and in assessing and interpreting growth data. Am. J. Hum. Biol. 9:709–715, 1997. © 1997 Wiley-Liss, Inc.     

Neonatal sex-steriod hormones and timidity in 6-18-month-old boys and girls

Five sex-steroid hormones (testosterone, androstenedione, estradiol, estrone, and progesterone) are assayed in umbilical cord blood. Timidity is assessed in home and laboratory observations by reactions to a range of novel toys in children from 6 to 18 months of age. Significant short- (1 week) and long- (several months) term stability in timidity is demonstrated. Girls have higher mean scores on observed timidity than do boys in 2 of the 3 samples tested. An across-age timidity score is computed which shows significant correlations with neonatal progesterone, testosterone, and estradiol for boys, but is not significantly predicted by hormone concentrations in girls.