Luteinizing hormone-releasing hormone in prepubertal and pubertal girls.

Estimations of immunoreactive LH-RH and LH in pooled sera of girls, adult women and postmenopausal women have been carried out. The girls were divided into three groups: I--girls aged 2--4 years, II--girls aged 5--8 years and III--girls 9--12 years of age. The estimated concentrations of LH-RH in particular groups were as following: in group I--1.2 +/- 0.2 pg/ml, in group II--2.2 +/- 0.4 pg/ml, in group III 31.0 +/- 4.4 pg/ml, in adult women 6.3 +/- 1.8 pg/ml. and in postmenopausal women 16.6 +/- 2.4 pg/ml. The concentrations of LH in the same groups were 4.3 +/- 0.7; 4.5 +/- 0.8; 11.0 +/- 1.4, 23.3 +/- 2.4; and 120.0 +/- 14.7 mIU/ml, respectively. The authors suggest that the sexual maturation of girls is initiated by the enhanced hypothalamic activity, reflected in higher concentrations of immunoreactive LH-RH in peripheral serum.     

Aerobic power and pubertal peak height velocity in Belgian boys

To determine the cardiorespiratory response to maximal exercise before, during and after the pubescent growth spurt, thirty boys were tested at yearly intervals over a period of six consecutive years. For each individual, peak height velocity (PHV) was determined. The age at PHV (X = 13.6 years) was taken as a standard of maturation. The results from all subjects at 1.5 and 0.5 years before and 0.5 and 1.5 years after PHV are presented. The highest oxygen uptake (VO2) obtained during an incremental bicycle ergometer test to voluntary exhaustion was taken as peak oxygen uptake (VO2 peak). Across each of the four years studied, mean VO2 peak (min = 49.6; max = 52.5 ml.kg-1.min-1) and mean heart rate (HR) at VO2 peak (min = 190; max = 192) did not change significantly as a function of PHV. On the other hand, the respiratory quotient at VO2 peak increased considerably from mean minima and maxima of 0.99 and 1.01 before PHV to 1.07 and 1.10 after PHV. Ventilatory equivalent for VO2 (VE/VO2), taken as an indicator of ventilatory economy, seemed to be unaffected by the maturation process. The steepest increase in circumpubertal oxygen pulse was found one year after PHV. Average stability coefficients (r), calculated from the inter-years correlations were high for height (r = 0.95), weight (r = 0.92), HR at VO2 peak (r = 0.74), VO2 peak in 1/min (r = 0.71), oxygen pulse (r = 0.68) and tidal volume (r = 0.64).     

Effects of different electrodes on bioelectrical impedance values

Effects of different electrodes on bioelectrical impedance values measured by the Selco bioelectrical impedance plethysmograph (SIF-881, Japan) were investigated using 8 adult females (age: 35.3 +/- 7.6 yr, Ht: 156.9 +/- 3.8 cm, Wt: 57.1 +/- 9.9 kg, and hydrodensitometrically determined body fat: 29.4 +/- 6.0%). The Lectec MP3000 electrode (Liberty Carton, USA) and the Bipolar electrode (Sanwa, Japan) produced significantly higher impedance values when compared to the Disposable electrode (Adovance, Japan) and the ECG electrode (Nihon Kohden, Japan). The coefficient of variation was significantly lower for the Disposable electrode (0.8%) and the ECG electrode (0.2%) than that for the Lectec MP3000 electrode (2.3%) and the Bipolar electrode (4.9%). In conclusion, the ECG electrode provides higher bioelectrical impedance values with the highest reproducibility in the assessment of human body composition by the bioelectrical impedance plethysmography.     

Validity of leg-to-leg bioelectrical impedance measurement in highly active women

The aim of this study was to compare the validity of the leg-to-leg bioelectrical impedance analysis (BIA) method with that of anthropometry using hydrostatic weighing (HW) as the criterion test. A secondary objective was to cross-validate previously developed anthropometric regression equations as well as to develop a new regression equation formula based on the anthropometric data collected in this study. Three methods for assessing body composition (HW, BIA, and anthropometric) were applied to 60 women university athletes. The means and standard deviations of age, weight, height, and body mass index (BMI) of athletes were as follows: age, 20.70 +/- 1.43; weight, 56.19 +/- 7.83 kg; height, 163.33 +/- 6.11 cm; BMI, 21.01 +/- 2.63 kg x m(-2). Leg-to-leg BIA (11.82 +/- 2.39) has shown no statistical difference between percentage body fat determined by HW (11.63 +/- 2.42%) in highly active women (p > 0.05). This result suggests that the leg-to-leg BIA and HW methods were somewhat interchangeable in highly active women (R = 0.667; standard error of estimate [SEE] = 1.81). As a result of all cross-validation analyses, anthropometric and BIA plus anthropometric results have generally produced lower regression coefficients and higher SEEs for highly active women between the ages of 18 and 25 years. The regression coefficients (0.903, 0.926) and SEE (1.08, 0.96) for the new regression formulas developed from this study were better than the all the other formulas used in this study.     

Natural selection on anthropometric traits of Estonian girls

Natural selection is a key mechanism of evolution, which results from the differential reproduction of individuals due to differences in phenotype. We describe fecundity selection on 13 anthropometric traits in a sample of 4000–10,000 of Estonian girls, who were born between 1937 and 1962 and measured at around 13 years of age. Direct selection favoured shorter, slimmer and lighter girls with smaller heads, more masculine facial and body shapes and slower rates of sexual maturation. Selection was stabilizing for weight, body mass index and face roundness. Direct selection was absent on two markers of general health and viability – handgrip strength and vital lung capacity – although these traits experience negative indirect selection due to their association with educational attainment. Similarly, indirect selection, mediated by educational attainment, accounted for a significant portion of selection for girls with smaller heads, narrower faces, and higher shoulder/hip ratios. These traits are thus subject to gene-culture coevolution, in that selection on body dimensions arises via cultural and behavioural mechanisms.     

Longitudinal study of anthropometric,skinfold, work,and motor characteristics of boys and girls,three to six years of age

Groups of preschool children were followed longitudinally: boys, n = 36, from 3.48 up to 6.02 years and girls, n = 22, from 3.53 up to 6.03 years. Anthropometric dimensions, skinfold thicknesses, reaction of the cardiovascular system to a work load (modified step test), motor performance, and hand grip strength were measured. Boys had greater values for height, weight, length, and circumferential measures, with the exception of the thigh. Boys had also smaller skinfolds and better performances in 20 meter dash, broad jump, cricket ball throw, and grip strength compared to girls. All anthropometric dimensions increased with age, but these increase did not have the same character. Children became more linear in spite of relatively greater increase in total body weight. Chest and abdomen circumferences increased more in boys during the last year of the study. Skinfold thicknesses decreased significantly in boys, and stayed the same in girls. Motor performance and muscle strength also increased during the experimental period. Pulse rate at rest, during modified step test and recovery period decreased with age, and the economy of cardiac work improved significantly as indicated by step test index and/or cardiac efficiency index. The changes derived from longitudinal observations corresponded to previous results of cross-sectional data.     

Physical fitness differences between prepubescent boys and girls

The purpose of this study was to analyze in which physical capabilities boys and girls are closer or distant. An additional objective was to find which of the body fat, physical activity, and somatotype factors have a greater effect on prepubescent children's physical fitness. This was a cross-sectional study involving 312 children (10.8 ± 0.4 years). The physical fitness assessment employed sets of aerobic fitness, strength, flexibility, speed, agility, and balance. The boys presented higher values in all selected tests, except tests of balance and flexibility, in which girls scored better. Gender differences in the physical fitness were greatest in the explosive strength of upper (p ≤ 0.01, η(p)(2) = 0.09) and lower limbs (p ≤ 0.01, η(p)(2) = 0.08), although with a medium-size effect of gender, and smaller in the abdominal (p > 0.05, η(p)(2) = 0.007) and upper limbs (p > 0.05, η(p)(2) = 0.003) muscular endurance, and trunk extensor strength and flexibility (p > 0.05, η(p)(2) = 0.001). The endomorphic (p ≤ 0.01, η(p)(2) = 0.26) in the girls, and the ectomorphic (p ≤ 0.01, η(p)(2) = 0.31) and mesomorphic (p ≤ 0.01, η(p)(2) = 0.26) in the boys, had the high-sized effect on the physical fitness. The physical activity in the girls, and the endomorphic and body fat in the boys, did not have a significant effect. These findings can help in the planning of activities that take into account the success and motivation of both boys and girls and thus increase levels of physical activity and physical fitness at school. However, in prepubescent children, one cannot neglect the influence of genetic determinism, observed from the morphoconstitutional point of view.     

Effects of orthostatic fluid shifts on bioelectrical impedance measurements

This study analyzes the effect of orthostatic fluid shift caused by body postural changes on the reliability and stability of bioelectrical impedance. It has been found that following a fluid distribution perturbation caused by postural changes, impedance values change for a period of time that can be longer than the measurement time. Based on these preliminary measurements, it is recommended that new measurement protocols for bioelectrical impedance be developed in order to minimize perturbations on existing fluid distribution, thus increasing the reliability of bioelectrical impedance data.     

Ethnic differences in the relationship between bioelectrical impedance and body size

The present study compared the regression equations of bioelectrical impedance on body size among various groups to investigate potential differences due to ethnicity. Data consisted of 30 Japanese and 28 Caucasoid subjects, and other groups of Aborigines, Danes, Melanesians and Polynesians from literature. The relationship between impedance and body weight fot the groups showed the ethnic difference. In the regression equations for Japanese and Caucasoid, a statistically significant difference was observed between both groups. The regression equation for Japanese was lower in the elevation. This seemed to be attributable to differences in the volume of fat-free mass for the same body build, configuration of the body, and fat-free mass density.     

Active core rewarming avoids bioelectrical impedance changes in postanesthetic patients

Background

Postoperative hypothermia is a common cause of complications in patients who underwent laparoscopic cholecystectomy. Hypothermia is known to elicit electrophysiological, biochemical, and cellular alterations thus leading to changes in the active and passive membrane properties. These changes might influence the bioelectrical impedance (BI). Our aim was to determine whether the BI depends on the core temperature.

Methods

We studied 60 patients (52 female and 8 male) age 40 to 80 years with an ASA I-II classification that had undergone laparoscopic cholecystectomy under balanced inhalation anesthesia. The experimental group (n = 30) received active core rewarming during the transanesthetic and postanesthesic periods. The control group (n = 30) received passive external rewarming. The BI was recorded by using a 4-contact electrode system to collect dual sets of measurements in the deltoid muscle. The body temperature, hemodynamic variables, respiratory rate, blood-gas levels, biochemical parameters, and shivering were also measured. The Mann-Whitney unpaired t -test was used to determine the differences in shivering between each group at each measurement period. Measurements of body temperature, hemodynamics variables, respiratory rate, and BI were analyzed using the two-way repeated-measures ANOVA.

Results

The gradual decrease in the body temperature was followed by the BI increase over time. The highest BI values (95 ± 11 Ω) appeared when the lowest values of the temperature (35.5 ± 0.5°C) were reached. The active core rewarming kept the body temperature within the physiological range (over 36.5°C). This effect was accompanied by low stable values (68 ± 3 Ω) of BI. A significant decrease over time in the hemodynamic values, respiratory rate, and shivering was seen in the active core-rewarming group when compared with the controls. The temporal course of shivering was different from those of body temperatue and BI. The control patients showed a significant increase in the serum-potassium levels, which were not seen in the active-core rewarming group.

Conclusions

The BI analysis changed as a function of the changes of core temperature and independently of the shivering. In addition, our results support the beneficial use of active core rewarming to prevent accidental hypothermia.     

Mucosal cytology in the determination of the pubertal status in girls

AIM: To assess and validate the diagnostic value of buccal and vaginal smears in the ambulatory care of girls with potential disorders of puberty. METHODS: Smears were obtained from 77 girls who presented for assessment of their pubertal status, stained as described by Papanicolaou, examined for signs of estrogenization according to the method of Schmitt, and compared with the clinical status. RESULTS: Vaginal but not buccal smears reflect accurately the changes of sexual maturation, even more sensitive than single serum hormone measurements. CONCLUSIONS: Vaginal smears represent a valid, reproducible, and well-tolerated diagnostic tool in the ambulatory care of peripubertal girls to identify their estrogen status with high sensitivity and specificity. The decision to perform confirmative but invasive diagnostic procedures can be based on auxology, physical examination, bone age determination, and analysis of vaginal smears.     

Bioactivity of luteinizing hormone during normal puberty in girls and boys

In order to evaluate the in vitro bioactivity of LH during normal puberty compared to LH immunoactivity measured in a highly sensitive immunoassay, blood plasma samples from healthy children were analyzed in a mouse Leydig cell assay (MLCA). Blood samples were obtained from 60 healthy girls and boys during normal pubertal development. Samples were taken on two occasions with a 1-year interval. Three daytime samples and three nighttime samples were analyzed. The correlation of the LH immunoradiometric assay (IRMA) activity with the LH activity in the MLCA varied from 0.60 to 0.96 in the different pubertal stages. During pubertal development, a gradually increase in the activity of LH in both the IRMA and MLCA was found. The ratio of the in vitro bioactivity compared to the immunoreactivity (B/I ratio) did not change significantly during puberty: it was 0.84 (SD 0.58) and 0.66 (SD 0.40) during the first and second sampling period in girls and 0.88 (SD 0.38) and 0.91 (SD 0.46, NS) in the boys. The B/I ratio of LH does not change during puberty. With a high sensitivity and specificity, measurement of LH by IRMA gives representative measurements of the LH in vitro bioactivity in children during pubertal development. Copyrightz1999S. KargerAG,Basel     

Longitudinal study on growth in height in Polish boys and girls

Physical growth and development of children, determined by endogenous factors (genetic and paragenetic) is modified by numerous exogenic ones. This affects differentiation of ways of growth in individual children. In order to estimate the individual growth patterns and changes in growth rate as well as differences in growth of boys and girls, one must observe the process of growth of the same children and over a period of many years (longitudinal study). Such longitudinal study is the only way to provide information about the variability of growth and growth velocity at each age.     

Estimation of body composition from bioelectrical impedance of body segments

This study provides values of anthropometric measurements and specific impedance, for a sample of 104 adults. The hypothesis that the body composition can be estimated more accurately from measurements of lengths and impedance values of the body segments than from the whole body was tested. The impedance of upper and lower extremities (arm and leg) and trunk were used to compute estimates of body composition parameters (FFM, FM, %F, TBW, ECW). The results were compared with those estimated by the impedance of the whole body. These comparisons demonstrated that significative differences resulted from body composition obtained by segmental impedance and by the whole body.