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Biomedical subjects

N Cameron

Publications and source records attributed to N Cameron.

At least 73 records · Page 4Linked to original sources
PubMedDate not supplied

British growth charts for height and weight with recommendations concerning their use in auxological assessment.

PRIMARY OBJECTIVE: To review the appropriateness of current British growth charts for height and weight. METHODS AND PROCEDURES: A review of their structure and function in the context of the problems posed by (1) secular trends for increasing size, (2) the external validity of source samples, (3) differences in the design and application of cross-sectional and longitudinal charts, and (4) the clinical significance of differences between current charts. MAIN OUTCOMES AND RESULTS: Charts pre-dating the Freeman et al. 1995 and the Buckler-Tanner 1995 charts should be considered obsolete for the purposes of growth assessment on a sample or individual basis. Either the Freeman or the Buckler-Tanner chart is suitable for screening, surveillance or monitoring prior to adolescence but the Freeman chart is recommended for screening and surveillance of samples of children throughout childhood and adolescence. When comprehensive growth and development data are available it is advantageous to use the Buckler-Tanner chart during adolescence for the diagnosis and monitoring of individual children.

Adolescent↗
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Pubertal development and sedentary behaviour during adolescence.

BACKGROUND: Assessing time spent in sedentary behaviours in relation to pubertal status, anthropometric differences, and body image will improve insight into the prevalence and determinants of such behaviours during adolescence. AIM: The study aimed to investigate the effects of age, puberty, gender, body composition, and sleep on sedentary behaviour. PARTICIPANTS AND METHODS: Participants were 64 boys and 55 girls in Year 6 (10.0-10.9 years of age), Year 8 (12.0-12.9 years) and Year 10 (14.0-14.9 years). Body mass index and percentage body fat were calculated from anthropometric measures. Sedentary behaviour and sleep time were computed using momentary-time sampling. Body image was measured using the Children's Physical Self-Perception Profile. Pubertal status was assessed from self-report of secondary sexual characteristics. RESULTS: After controlling for sleep time, no differences in sedentary time were seen for puberty onset or increased pubertal development. Correlations between pubertal status, body composition, and body image were stronger in girls than in boys. Correlations between body image and sedentary behaviour were not strong enough to infer behavioural choice differences. CONCLUSIONS: Reduced sleep time rather than changing body image and body composition during adolescence is associated with greater sedentary behaviour.

Adolescent↗
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The growth of London schoolchildren 1904-1966: an analysis of secular trend and intra-county variation.

Height and weight were measured on 299,303 children involved in eleven London County Council Surveys dating from 1904 to 1966. This paper describes the historical background to these surveys, the secular trend towards increasing heights and weights and a decreasing age at menarche, and the variation of height and weight between parts of the county. All the surveys were cross-sectional, but that of 1966 included yearly velocity data on 13,806 children. Means for height and weight by age and sex were adjusted to the exact half year to allow comparison of all surveys. Menarcheal age was determined by probit analysis on status quo data in 1954, 1959 and 1966. Intra-county comparisons were based on the Divisional Index of the nine Area Health Divisions of the County. The results indicate an end to the positive secular trend for height and weight at about the same time as the previously reported end to a decreasing age of menarch in London girls. Intra-county comparisons indicated different rates of secular trend within different areas favouring those children who were the smallest and lighest in 1949. The end of the secular trend is thought to be due to genetic factors and intra-county changes to improve environmental conditions.

Adolescent↗
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The reproducibility of TW2 skeletal age assessments by a self-taught assessor.

An investigation into the reproducibility of TW2 skeletal age assessments was carried out using three observers. The first, G.B., had learned the technique without expert advice, while the second, R.H.W., was one of the originators of the technique. The third, N.C., was an experienced rater orginally trained by R.H.W. G.B. and R.H.W. were compared using a standard set of 112 X-rays arranged in a random order. G.B. was compared to N.C. using a random sample of 50 X-rays from the Leuven Growth Study of Belgian Boys. The percentage agreement in rating all 20 bones was just over 83% in both analyses. Higher percentage agreements were found in both analyses for the round bones (88% and 85.1% respectively) as opposed to the radius, ulna and short bones (81.3% 82.1% respectively). Significant differences were found in mean bone-age between G.B. and R.H.W. and between G.B. and N.C. for TW220 and carpal bone ages. No significant differences in mean bone-ages were found for RUS bone-ages. The reproducibility of the self-taught assessor was found to be as good as that of assessors trained by the originators of the technique or experienced raters.

Age Determination by Skeleton↗
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Conditional standards for growth in height of British children from 5.0 to 15.99 years of age.

Conditional standards giving centiles for height at time (t + 1) given height at time (t) are illustrated and their use discussed with the aid of examples. Charts have been prepared for both sexes covering the age range of t of 5.0 to 15.99 years. In contrast to velocity standards, these standards utilize all the information inherent in height (t) and height (t + 1). The conditions of their use, however, must be carefully considered. It is stressed that they actually test the normality of height (t + 1) for a given height (t). They make no statement about the normality of height (t).

Adolescent↗
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Investigation of the mid-growth spurt in height, weight and limb circumferences in single-year velocity data from the London, 1966-67 growth survey.

In the 1966-67 London County Council Survey, some 10 000 children were measured twice, on occasions one year apart. Mean single-year velocities were calculated for each successive 6-month period from age centre 5 1/2 to maturity, for height, weight, upper arm and calf circumferences and triceps and subscapular skinfolds. The velocity curves, in which successive points are independently ascertained, were examined for evidence of a mid-growth spurt. In weight and limb circumferences there was a clear increase of velocity occurring from about 6 1/2 to 7 1/2 in girls and from 7 to 8 in boys. From the end of the mid-growth spurt to the beginning of the adolescent spurt, about three years later, weight velocity remained constant, but limb circumferences velocities mostly dropped. All or most of these changes in velocity can be accounted for by changes in rate of fat deposition. Girls showed no evidence of a mid-growth spurt in height, but boys had a diminution of deceleration, or relative spurt, from about 6 to about 7. These results could be accounted for if some, but not all, individual children have mid-growth height spurts. Graphs of the single-year actual-increment medians show slight differences from the standard population velocity medians, the actual-increment curves being a little more complicated than the smoothed standards.

Adolescent↗
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Skeletal maturity of well-off children in Chandigarh, North India.

Attained mean heights, weights and skeletal maturity assessed by the TW2 method of well-off North Indian (Chandigarh) children ranging in age from 6 years to 12 years (96 girls) and 14 years (202 boys), were compared with British Standards. The mean height of girls remained close to the 50th centile and their weights to the 25th centile. Boys' mean heights and weights were close to the 50th centile up to age 9 years; later they slowly shifted to the 25th. Girls' RUS skeletal maturity remained between the 50th and 75th centiles of the British standards while boys, though having a tendency to be advanced at certain ages, were practically at par with the British 50th centile. The pattern of carpal maturity was different; girls reached full carpal maturity at the same age as British girls, but boys showed retardation.

Adolescent↗
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Longitudinal comparison of aerobic power in active and inactive boys aged 7.0 to 17.0 years.

Height and maximal aerobic power (VO2 max) were analysed longitudinally in 14 active and 11 inactive boys from the Saskatchewan Longitudinal Growth Study. VO2 max values were obtained from a treadmill run repeated each year. The Preece-Baines Model I was fitted to height and VO2 max values over the duration of the study. No significant differences were found for height attained between the two groups. VO2 max comparisons revealed no significant differences before the take-off point for the adolescent growth spurt. Significant differences occurred in the VO2 max attained by the age of peak adolescent velocity in VO2 max, the increase from take-off to peak and in the adult value, with active boys having higher values. It is concluded that activity before adolescence causes no significant increase in VO2 max, but that adolescence is the critical period during which consistently higher rates of increase in the VO2 max of active boys result in a significantly greater adult value.

Adolescent↗
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A longitudinal analysis of the growth of limb segments in adolescence.

The growth of upper and lower-limb segments of 96 adolescent boys and girls from the Royal Hospital School Longitudinal Study was analysed. Preece-Baines Model 1 curves were fitted to the longitudinal data to obtain, for each measurement, age at peak velocity and the magnitude of this velocity. Mean-constant peak velocities were between 1-0 and 2-5 cm/yr in all segments. They were in all cases greater than the values obtained from fitting the P-B curve to the cross-sectional means at successive ages. Boys had greater peak velocities than girls in all measurements (sex ratio 1-1 to 1-4). On average distal segments preceded more proximal segments in the ages at which peak velocity occurred. Considerable individual differences, however, occurred in the order for the upper limb segments. These differences seemed to be related to the individual's tempo of growth; late developers had a significantly different order to early developers.

Adolescent↗
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Increase in length of leg relative to trunk in Japanese children and adults from 1957 to 1977: comparison with British and with Japanese Americans.

The secular trends in height, sitting height and leg length in Japanese children have been studied by fitting Preece-Baines Model I curves to the annual mean values from ages five to 17 of school data collected in 1957, 1967 and 1977. The method provides estimates of final adult value, and of age of maximum annual increment. Between 1957 and 1977 the maximal increments in height, sitting height and leg length all became earlier, by about a year in boys and a little less in girls. Japanese now mature about a year earlier than North Europeans. Adult height increased by 4.3 cm in boys and 2.7 cm in girls between 1957 and 1977, the increment being less in the second decade than in the first. Sitting height showed practically no increase whatever; almost the whole secular trend was due to change in leg length. Japanese now have trunk/leg proportions much more similar to those of North Europeans than was the case 20 years ago, but their adult height remains about one standard deviation lower.

Adolescent↗
PubMedDate not supplied

BASIC programs for the assessment of skeletal maturity and the prediction of adult height using the Tanner-Whitehouse method.

A family of BASIC microcomputer programs is described that carry out the computations required for the assessment of skeletal maturity and the prediction of adult height according to the Tanner- Whitehouse techniques. These programs significantly reduce the tedious computations required for these assessments and present final data in a comprehensible format. Both the original, Mark 1, and the newer, Mark 2, prediction methods are included because even though the latter is intended to replace the former, this replacement will naturally take some time and comparability studies will inevitably be undertaken. The programs are written in Applesoft BASIC but may be easily modified for other microcomputers or main-frames with the facility for BASIC compilation.

Age Determination by Skeleton↗
PubMedDate not supplied

The application of new height-prediction equations (Tanner-Whitehouse mark 2) to a sample of Canadian boys.

The adult statures of a sample of 71 Canadian boys from the Saskatchewan Longitudinal Growth Study were predicted using the original TW Mark 1 and the new TW Mark 2 prediction equations. The subjects had a mean chronological age of 11.59 years (SD = 0.30), a mean RUS bone age of 11.62 'years' (SD = 1.18), a mean height of 145.0 cm (SD = 6.98) and a mean measured adult height of 177.2 cm (SD = 6.65). The Mark 2 equations improved the predictions over Mark 1 by an average of 0.2-0.6 cm and slightly reduced the range of errors. No improvement in the prediction of boys above the 75th centile of British standards was noted but 60-70% of boys below the 25th centile predicted better with the Mark 2 equations. This pattern may well be repeated in more extreme subjects. About 80% of individuals who predicted badly with the Mark 1 equations, i.e. with errors equal to or greater than 5 cm, improved their predictions when Mark 2 equations were used.

Body Height↗
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Evidence for a secular trend in the Negro dentition.

Metric changes in the Negro dentition were evaluated in a sample of artificial stone casts of the dental arcades of 106 living South African Negroes (56 males, 50 females) and in 100 Negro crania (50 males, 50 females) drawn from the R. A. Dart Collection. Comparison of the mesiodistal and buccolingual dimensions of these two samples to the published results of a similar study on earlier Negroes revealed a statistically significant trend towards tooth-size enlargement. This positive secular trend was found to be most pronounced in the mesiodistal diameter, with less than half of the teeth considered showing significant buccolingual enlargement. Although the trend was equally pronounced in both sexes and in both arcades, mesiodistal change was found to increase in an antero-posterior direction, while buccolingual change centred around the anterior teeth.

Black People↗
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Secondary sexual development of 'Cape Coloured' girls following kwashiorkor.

This report describes the secondary sexual development of 45 'Cape Coloured' female ex-kwashiorkor patients and 43 female controls. All patients were originally seen between five months and four years four months of age, treated and then followed up for 15 years after discharge. Age at menarche was available on 42 ex-patients and 33 controls, and age at peak height velocity (PHV) was available for 30 ex-patients and 15 controls. Maximum likelihood estimates of the mean age at entry to each pubertal stage were made, age at menarche was obtained directly from the subject records and age at PHV was obtained by fitting a non-linear growth function to the data for each subject. All subjects passed through the sequence of pubertal events in the normal order, i.e., no reversals were observed. Ex-patients were generally delayed in relation to controls but there were no significant differences for ages at entry to any of the pubertal stages. The subjects were combined for comparison to equivalent data on British girls. The South African girls were significantly delayed in the development of pubic hair and menarche but showed no significant differences for age at entry or duration of breast development and PHV. It is suggested that lack of delay in breast development may have selective advantages to females living in situations of chronic malnutrition.

Female↗
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Secondary sexual development of Cape coloured boys following kwashiorkor.

This report describes the secondary sexual development of 78 Cape Coloured male ex-kwashiorkor patients and 53 male controls. All patients were originally seen between 5 months and 4 years 4 months of age, treated and then followed up for 15 years after discharge. Age at peak height velocity (PHV) was available for 23 ex-patients and 15 controls. Maximum likelihood estimates of the mean age at entry to each pubertal stage were made and age at PHV was obtained by fitting a non-linear growth function to the data for each subject with appropriate serial height records. No significant differences were observed between ex-patients and controls for either the sequence of pubertal events or for the age of entry to each stage. When compared to a sample of normal British boys the Cape Coloured sample exhibited significant delay for ages at entry to all pubertal stages with differences ranging from 0.84 years for PH2 to 1.94 years for PH5. It is suggested that adrenal androgens play a major role in delaying secondary sexual development during chronic malnutrition and that the anterior pituitary's response to such conditions is to selectively delay pubertal status.

Adolescent↗
PubMedDate not supplied

Measurement error in human dental mensuration.

The reliability of human odontometric data was evaluated in a sample of 60 teeth. Three observers, using their own instruments and the same definition of the mesiodistal and buccolingual dimensions were asked to repeat their measurements after 2 months. Precision, or repeatability, was analysed by means of Pearsonian correlation coefficients and mean absolute error values. Accuracy, or the absence of bias, was evaluated by means of Bland-Altman procedures and attendant Student t-tests, and also by an ANOVA procedure. The present investigation suggests that odontometric data have a high interobserver error component. Mesiodistal dimensions show greater imprecision and bias than buccolingual measurements. The results of the ANOVA suggest that bias is the result of interobserver error and is not due to the time between repeated measurements.

Analysis of Variance↗
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Urban-rural differences in the growth of South African black children.

Urbanization is a major migratory process characteristic of developing countries. The majority of comparisons of the growth of urban and rural children from developed countries reflect greater heights and weights, and by implication health, of urban children. Urban-rural comparisons of South African black children are few in number and have concentrated on 'average' children, thereby omitting the factor of socioeconomic status. The present study compares two groups of urban children of high (n = 307) and average (n = 867) socioeconomic status and two groups of rural children. The rural children came from farm labourer's families (n = 392) and traditional subsistence farming environments (n = 420). The children ranged in age from 5 to 19 years. In general the well-off urban children were consistently, but not significantly, larger than all other groups and 'average' urban children were consistently and at times significantly smaller and lighter. The growth of the two rural groups fell between these extremes but were also consistently different in that the children of farm labourers were significantly lighter at all ages than children living in a traditional subsistence economy. It is concluded that the average urban environment in South Africa is not conducive to improved growth and health unless it is accompanied by an improved socioeconomic status.

Adolescent↗