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Biomedical subjects

J Karlberg

Publications and source records attributed to J Karlberg.

At least 127 records · Page 7Linked to original sources
PubMed1989

An approach to the estimation of growth standards: the univariate case.

This paper shows how reference values can be determined when the underlying characteristic (say, weight) follows a distribution that is not too distant from the Gaussian. Application of the normalizing Box-Cox power transformation is the basis of our approach. This transformation is monotonic and hence invertible, so offering the choice of two scales of measurement on which to work--the original and the Gaussian. Modified versions of the procedure are provided allowing use of the basic transformation in the presence of certain deficiencies in the data, principally measurement error and misclassification. It is shown that application of Box-Cox to a cohort at several points in time can be quite revealing. When the data are already symmetrical the Box-Cox transformation has no effect: in this case the John-Draper modulus transformation and modifications of it are shown to be helpful. All of this is illustrated by using data from the Swedish Longitudinal Growth Study.

Female↗
PubMed1989

Growth disturbance in an urban area of Lahore, Pakistan related to feeding patterns, infections and age, sex, socio-economic factors and seasons.

Infantile growth in 910 longitudinally-followed infants in a poor urban population of Lahore, Pakistan was followed from birth to two years of age and correlated to various socio-economic variables, infections, and feeding-practices. Attained body size was correlated with the number of episodes of diarrhoea and with family educational level and also, to some extent, with housing standards. The influence of environmental factors on growth was greatest during the hot and warm seasons, for children at an age of 6-9 months and in this culture especially for girls. Children living under the same conditions showed great individual variations in resistance to environmental factors as measured by growth parameters.

Age Factors↗
PubMed1989

A biologically-oriented mathematical model (ICP) for human growth.

A new approach to modelling the individual human linear growth curve from birth to maturity is presented in detail. The model, which is also suitable for other measurements, breaks down growth mathematically into three additive and partly superimposed components--Infancy, Childhood and Puberty (the ICP-model). A key feature of this approach is that these components of the human growth curve from birth to adulthood strongly reflect the different hormonal phases of the growth process. As a result, the model provides an improved instrument for detecting and understanding growth failure. The model also sheds light on some central facets of human growth. For instance, the dramatic change in body proportions during the first years of life is found to be related to an enhanced influence of the Childhood component on the legs as compared with the trunk. The size of the Puberty component is shown to be time-invariant and to be superimposed on the decelerating Childhood component during adolescence. Early pubertal maturation is known to give a higher peak velocity than late maturation, so this variation in pubertal gain must be explained by the shape of the Childhood component alone.

Body Height↗
PubMed1989

On the construction of the infancy-childhood-puberty growth standard.

Using the infancy-childhood-puberty (ICP) growth model, the postnatal linear growth curve is mathematically broken down into three components: infancy, childhood and puberty. The fact that each component of this model seems to represent a defined biological phase of the growth process, extends its clinical application. The principles used to construct the ICP growth standard and the basic 'clinical' ICP-based growth charts are described. These charts have a number of advantages over the conventional growth charts currently in use. Most importantly, the ICP growth chart provides reference values not only for total growth but also for each of the three individual components. Using this methodology, the magnitude and the onset of each component can be assessed in an individual child. The age at onset of the childhood component, which is a newly discovered and important feature of human growth, can easily be detected in an individual child. Furthermore, prepubertal growth, onset of puberty and pubertal growth can be accurately assessed, because the difference in pubertal maturation is taken into account when setting standards during adolescence. The methodology also offers a new and highly accurate predictor of final height and permits assessment of growth rates over shorter and longer periods using a simple and effective method of assessing change. The ICP growth model appears to be a refined instrument for detecting and understanding growth disturbances.

Adolescent↗
PubMed1988

Early affective antecedents of adult type A behavior.

The early affective, apparently temperamental antecedents of Type A behavior were investigated in a Swedish longitudinal sample (N = 149). Four clusters of Type A items (describing irritability, hurried behavior, work achievement, and competitiveness) were regressed on maternal ratings of the child's poor appetite, sleep disturbances, liveliness, anger, and shyness, collected annually from infancy to adolescence. The child's liveliness, sociability, and poor appetite during infancy and childhood were positively related to the adult Type A irritability and hurried behavior clusters, as were the mother's liveliness, orderliness, and intelligence as rated by psychologists during the child's first 6 years. The two work-involvement clusters were predicted by interactive effects among shyness, poor appetite, and anger during adolescence but were unrelated to mother attributes. Sleep disturbances were only related to competitiveness and only in late adolescence. These findings indicate that the interrelated components of adult Type A behavior have contrasting developmental histories and that temperament-related constructs are important antecedents to the adult syndrome.

Achievement↗
PubMed1988

Infancy growth pattern related to growth hormone deficiency.

Linear growth during the first three years of life can be represented mathematically in terms of the "ICP-growth model", using a combination of a quickly decelerating Infancy component with the addition of a slowly decelerating Childhood component, the latter acting from the second half of the first postnatal year. The growth pattern for supine length of four children with growth hormone (GH) deficiency is related here to the first two components of this growth model. Basically, all four infants displayed a pattern in line with the exponential shape of the Infancy component to the age when GH therapy was initiated. This observation indicates the existence of the Infancy component as it has been adopted for the ICP-model, and also that it represents the part of postnatal linear growth which seems to be independent of GH. The onset of the Childhood component in healthy subjects has been observed as an abrupt increase in growth rate during the second half of the first year of life. A similar abrupt increase was observed in this study at the time of the initiation of GH therapy (16-27 months). This observation gives some further empirical support to the hypothesis that the child's age at onset of the Childhood component defines the as yet undetermined age at which GH begins to exert a significant influence on linear growth. ICP-based growth charts provide an improved instrument for early detection of GH deficiency.

Age Factors↗
PubMed1988

Longitudinal analysis of infantile growth in an urban area of Lahore, Pakistan.

Supine length has been registered longitudinally in 302 infants surviving to at least two years of age in an urban area of Lahore, Pakistan. According to the "ICP-growth model", normal linear growth can be represented during this age period by a combination of a sharply decelerating Infancy component with the addition of a slowly decelerating Childhood component, the latter acting from the second half of the first postnatal year. Between birth and 24 months of age the Pakistani children grew about 7.5 cm less than expected according to the Swedish standard. The difference in the gain was mainly related to the late onset of the Childhood component found in 56% of the infants. The onset of the Childhood component in the Pakistani children occurred on an average some 5 months later than in the Swedish controls, which explains the age-dependent reduction in the gain at about 1 year of age. Children with late onset showed no "catch-up growth" during the observation period after the onset. This might very well indicate the functional implications of stunted height in populations of developing countries.

Age Factors↗
PubMed1988

Longitudinal analysis of infantile growth in children with celiac disease.

The aim of the present study was to describe linear growth of infants with celiac disease, using the "ICP-growth model". Supine length during the first three years of life was studied longitudinally in 63 infants with diagnosed celiac disease. "Undisturbed" linear growth was seen during the first six postnatal months followed by reduced growth during the second half of the first year. After 1.5 years of age a pattern of catch-up growth was observed, leading to an average attained length at 3 years of age similar to that of the controls. According to the "ICP-growth model", normal linear growth can mathematically be represented during the first 3 years of life by an Infancy component with the addition of a Childhood component, the latter acting from the second half of the first postnatal year. The onset of the Childhood component (assumed to represent the age at which growth hormone begins to influence linear growth significantly) was delayed by about an average of 3 months, which is in agreement with the observed reduction in gain during the second half of the first year of life. Children suffering from celiac disease and with "late" onset of the Childhood component were shorter at 1, 2 and 3 years of age than those with "normal" onset. The results of this investigation show that ICP-based growth charts are helpful in detecting and monitoring growth for children with celiac disease, and indicate a possible mechanism whereby malabsorption (and perhaps secondary malnutrition) leads to reduced growth velocity.

Age Factors↗
PubMed1988

Growth in children treated for acute lymphoblastic leukemia with and without prophylactic cranial irradiation.

Growth and weight gain were studied longitudinally over a period of four years in thirty-nine children treated for acute lymphoblastic leukemia. The children were divided into two groups according to treatment. Twenty-eight children were given prophylactic cranial irradiation and eleven children were treated without such irradiation. The duration of cytostatic treatment was three years in all cases. Average growth during the first two years was similar in the two groups, and the standard deviation scores (SDS) were below average. The rate of growth (in height) during the fourth year was significantly higher among those children who had not received cranial irradiation (p less than 0.01). After four years the average attained height had declined 0.5 SD for children treated with cranial irradiation and 0.2 SD for children without such treatment. Weight velocity was significantly greater than the expected mean in the non-irradiated group during the first year and in the irradiated group during the fourth year of the study. Attained weight after four years had increased 0.4 SD more among those children who had not received irradiation. The results suggest that prophylactic cranial irradiation is responsible for the greater part of the prepubertal growth inhibition in these children.

Child↗
PubMed1988

Grenz ray therapy: practical aspects of protecting office personnel from radiation.

The exposure to grenz rays of office personnel handling a grenz ray unit working with 10 kV voltage was investigated for different treatment situations. Scattered and leakage radiation, and primary radiation at some distance from the grenz ray unit were measured. Air absorption was found to be most important. Direct exposure of the operator to the primary grenz ray beam at a distance of 4 m was practically nil. At a distance of 2 m from the unit, the operator is permitted to be exposed 100 h per year; at a distance of 1 m, the permitted exposure of the direct beam is 3 h per year. Scattered and leakage radiation from the unit was of no importance and certain clothing was demonstrated to promote absorption.

Dermatology↗
PubMed1987

On the modelling of human growth.

A new approach to modelling human linear growth from birth to maturity is presented. The model splits growth into three additive and partly superimposed components, appropriately named infancy, childhood and puberty; we refer to it as the ICP-model for obvious reasons. A key feature of this model, compared with others, is that the components correspond with known features of the endocrinological regulation of growth and can be considered in isolation from one another.

Adolescent↗
PubMed1987

The relation of stress hormone excretion to type A behavior and to health.

The relation between catecholamine and cortisol excretion and Type A behavior, assessed using an 11-item self-report questionnaire based on the Jenkins Activity Survey, is examined in a Swedish sample of young adults (N = 149). Cluster analysis indicates that the items measure four aspects of Type A behavior: irritability, hurried behavior, work achievement, and competitiveness. These clusters are not correlated with measures of recent health care utilization. In both sexes, a higher total Type A behavior score is related to decreased daytime urine concentrations of norepinephrine and day and night concentrations of cortisol. In males, increased hurried behavior is related to lower night levels of norepinephrine; higher irritability and competitiveness predict lower night levels of epinephrine and cortisol and increased urine excretion rate. In females, higher irritability and lower competitiveness scores are related to increases in daytime urine excretion and slightly lower levels of cortisol. These results indicate that only certain aspects of the Type A syndrome are related to stress processes and imply that the behaviors serve to lower stress responses in early adulthood.

Adult↗
PubMed1987

Analysis of linear growth using a mathematical model. I. From birth to three years.

According to the "ICP-growth model" (ICP = Infancy, Childhood and Puberty components), linear growth during the first three years of life can be represented mathematically by a combination of a sharply decelerating Infancy component and a slowly decelerating Childhood component. Growth as measured by supine length is analysed for 191 longitudinally followed healthy infants using this model. The main aim is to devise ICP-based methods for biological and clinical applications. The onset of the Childhood component, which occurs some time between 6 and 12 months of age and is typically abrupt, can be detected on an individual basis. Its starting point probably defines the as yet unknown age at which growth hormone begins to exert a significant influence. The analyses have also revealed some new facets of linear growth. Most infants are found to have a non-linear decelerating Infancy component, free from seasonal influence. Age at onset of the Childhood component is earlier for girls than for boys and is positively related to the magnitude of the Infancy component. During the second year of life the variation in growth rate of the cohort increases. This fluctuation is found to be seasonal and greater for those with late onset of the Childhood component. During the third year of life the growth pattern is stabilized.

Age Factors↗
PubMed1987

Analysis of linear growth using a mathematical model. II. From 3 to 21 years of age.

The 'ICP growth model' (ICP = Infancy, Childhood and Puberty components) represents linear growth from 3 years of age to maturity by a combination of a slowly decelerating childhood component together with a sigmoid puberty component, the latter acting only during adolescence. Linear growth is analysed for 157 longitudinally followed healthy infants using this model. The main aim is to assess the ability of the ICP model to describe and evaluate individual growth patterns in healthy children with particular emphasis on the considerable individual variation in the timing of puberty and the shape of the pubertal growth spurt. The use of the model to evaluate growth longitudinally over both short and long periods is also outlined. Reference values based on the ICP approach, the ICP Standard, seem to have a number of advantages in comparison with cross-sectional standards. In the 'Prepubertal ICP Standard', the contribution of the puberty component is omitted. The standard can be applied on an individual basis to evaluate prepubertal growth and pubertal onset, independently of the timing of puberty. By using the 'Pubertal ICP Standard' both the difference in pubertal maturation and the negative relationship between the size of the pubertal gain and the timing of puberty are taken into account. The fact that the gain in the puberty component is time-invariant, and can thus be aligned with the timing of puberty for an individual child, forms the basis of this approach. The analyses have also revealed a new predictor for final height, which is termed HAPO (height adjusted for pubertal onset). This predictor is based on age and attained size at onset of puberty--the 'onset' regression line.

Adolescent↗
PubMed1987

Growth of children with physiolysis of the hip.

Growth during adolescence was analyzed in 40 children with slipped capital femoral epiphysis using the Infancy Childhood Puberty growth model. The advantage of this model is that reference values for height can be adjusted for the individual age at pubertal maturation. In both sexes an above average height was found before the onset of the pubertal growth spurt. However, the pubertal gain in height was less than normal, and at maturity the heights were only slightly above the reference mean values. Most of the children had their first hip symptoms during the period of increasing gain in height at the initial stage of the pubertal growth spurt. Both boys and girls were overweight before puberty and remained so during puberty and at maturity.

Adolescent↗
PubMed1986

Long-term treatment with corticosteroids/ACTH in asthmatic children. IV. Skeletal maturation.

Skeletal maturation in severe bronchial asthma was studied in 15 children during and after treatment with depot tetracosactrin and in 6 children during treatment with prednisolone. Attained skeletal maturity before treatment was below the reference mean in the majority of children. Skeletal maturation was enhanced during treatment with depot tetracosactrin, which led to more advanced attained skeletal maturity at withdrawal than at start of treatment. There was a tendency towards larger increases of skeletal maturity than of height. The influence of adrenal androgens, released by ACTH-stimulation and good control of the disease are probably relevant factors for the acceleration of skeletal maturation. After withdrawal of depot tetracosactrin the rate of skeletal maturation normalized. During prednisolone treatment there was a delay of skeletal maturation leading to a progressive relative decrease of attained skeletal maturity, and closely related to a delay in linear growth. Treatment with depot tetracosactrin may thus induce enhancement of skeletal maturation, but with the treatment regimen found to be efficacious in bronchial asthma, the effect is not very pronounced and does not perceptibly affect the ultimate outcome of growth.

Adolescent↗
PubMed1985

A longitudinal study of growth in children with acute lymphoblastic leukemia.

Growth in terms of both height and weight was studied in a longitudinal sample consisting of ten children who all experienced the onset of acute leukemia between 18 months and 7 years of age. In spite of the lack of deviation in body size at birth, these children had somewhat higher values for attained size than the reference group one year before diagnosis. The information from this study showing a decrease in growth rate before the start of treatment, could suggest that the disease causes the growth failure. Growth rate for height increased with time from the first year of treatment, which could be correlated to a positive effect of medical treatment of the disease. These results indicate a very stable regulation of growth between 18 months and 12 years of age. The children dropped temporarily in mean one standard deviation (SD) corresponding to about 4 cm, from one year before the start of treatment to the end of the three years of treatment. It seems, however, that it is possible for the body to repair such a temporary growth inhibition as is seen in the catch-up growth during the following two years. Height measured in SD for the group two years after discontinuing treatment was practically the same as height at the time of the start of treatment. Children with leukemia during the first years of life and during the pubertal period may not show a similar growth pattern.

Age Factors↗