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Biomedical subjects

J M Wit

Publications and source records attributed to J M Wit.

At least 109 records · Page 6Linked to original sources
PubMed1997

Anthropometry and body composition in children.

Changes in body fat, fat-free mass and extracellular water occur in many disorders, and during normal growth in children. Thus, body composition is an increasingly important measurement in paediatric clinical practice, and is used for diagnostic purposes, for decisions for treatment and for monitoring improvement. A number of different methods exist for determining body composition in children; however, their use is complicated by the absence of a gold standard and the lack of validity data in children both with and without growth disorders. In this report, validity and usefulness are compared among anthropometric methods and weighted against other techniques used in children. Recent recommendations of a number of expert committees are discussed.

Adipose Tissue↗
PubMed1997

Catch-up growth.

Explore the source record for details and available documents.

Aging↗
PubMed1996

Catch-up growth after prolonged hypothyroidism.

UNLABELLED: This report presents an analysis of four patients who suffered from longstanding untreated hypothyroidism, with special attention to the phase of catch-up growth after the start of L-thyroxine treatment. Although a permanent height loss could not be prevented, the capacity to establish a remarkable catch-up growth spurt proved to be still intact, even after a long period of thyroid dysfunction. CONCLUSION: Catch-up growth in hypothyroidism may be incomplete if treatment has been started shortly before or during puberty.

Adolescent↗
PubMed1996

Final height and hormonal function after bone marrow transplantation in children.

AIM: To analyze final height and hormonal function in long-term survivors of bone marrow transplantation (BMT). PATIENTS: Group 1 consisted of 16 patients (10 boys) with a hematologic malignancy, mostly leukemia, conditioned for BMT with total body irradiation (TBI), 7.5 to 12 Gy, and cyclophosphamide. Group 2 consisted of 14 patients (9 boys) with severe aplastic anemia, conditioned with chemotherapy only. RESULTS: In group 1, patients achieved a reduced final height after BMT. The difference between the height standard deviation score (SDS) at BMT and the height SDS at final height was -1.96 (0.82) SDS in boys and -0.92 (0.71) SDS in girls (p = 0.0001, and p = 0.02 respectively). Final height was also lower than target height (boys, p = 0.01; girls, p = 0.03). Prepubertal growth in the first 3 years after BMT was normal but pubertal height gain was decreased. The patients in group 2 achieved normal height. Thyroid function and adrenal function were normal in all patients, and no growth hormone deficiency was detected. Serum follicle-stimulating hormone values after BMT were increased in all group 1 patients, with return to normal in two patients. Serum luteinizing hormone values were increased in all group 1 girls, with recovery in one girl. Normal serum luteinizing hormone values and spontaneous puberty were found in all group 1 boys. In group 2, disturbances in gonadotropins were seen only in three boys and two girls. CONCLUSION: In patients treated in childhood with BMT after chemotherapy and TBI with 7.5 Gy or more, final height is compromised because of blunted growth in puberty. Patients who had not received TBI suffered no height loss. In the majority of patients, the combination of chemotherapy and TBI also resulted in irreversible disturbances of gonadal function.

Adolescent↗
PubMed1996

Restricted catch-up growth after cessation of steroid treatment in a growth-hormone-deficient child.

The phenomenon of catch-up growth has been known for a long time but its actual stimulus has remained unidentified. Involvement of growth hormone (GH) seems likely, but it is unknown whether normal GH secretion is an absolute prerequisite for catch-up growth. We present insight to this topic by describing a child with GH deficiency who showed a biphasic pattern of catch-up growth. During the first catch-up phase, she showed restricted catch-up growth in the absence of GH therapy, while she achieved nearly complete catch-up with GH therapy. Both periods of catch-up growth are compared separately with the response to GH therapy of age-matched, GH deficient patients with similar height deficit. This observation suggests that the first phase of catch-up growth in a child with severe growth retardation may be partially GH independent, while further catch-up requires normal GH levels.

Child, Preschool↗
PubMed1996

Spontaneous growth in idiopathic short stature. European Study Group.

Documenting the spontaneous growth pattern of children with idiopathic short stature (ISS) should be helpful in evaluating the effects of growth promoting treatments. Growth curves for children with ISS were constructed, based on 229 untreated children (145 boys and 84 girls) from nine European countries. The children were subdivided according to target range and onset of puberty, and the growth of these subgroups was evaluated from standard deviation scores (SDS). At birth, children with ISS were already shorter than normal (means; boys -0.8 SDS, girls -1.3 SDS). Height slowly decreased from -1.7 SDS at the age of 2 years to -2.7 SDS at the age of 16 years in boys and 13 years in girls. Final height was -1.5 SDS in boys and -1.6 SDS in girls (mean (SD): boys 164.8 (6.1) cm, girls 152.7 (5.3) cm)), which was 5-6 cm below their target height. The onset of puberty was delayed (boys 13.8 (1.3) years, girls 12.9 (1.1) years). Subclassification resulted in similar growth curves. These specific growth data may be more suitable for evaluating the effects of growth promoting treatments than population based references.

Adolescent↗
PubMed1996

Pit-1: clinical aspects.

Pit-1 is a transcription factor which is expressed in the somatotrope, lactotrope, and thyrotrope cell population of the anterior pituitary gland from early fetal development throughout life. Mutations in the Pit-1 gene result in insufficient expression of this factor, accounting for a form of combined pituitary hormone deficiency for growth hormone (GH), prolactin, and thyroid-stimulating hormone. Clinical presentation at diagnosis can be variable, although all forms finally result in severe growth retardation due to GH deficiency and hypothyroidism. The clinical variability is due to other factors than the exact location of the mutation; however, the type of inheritance seems to correlate well with the genotype. Early detection of Pit-1 abnormalities might prevent the sequelae associated with some early and severe presentations of this disorder.

Animals↗
PubMed1996

Spontaneous growth and response to growth hormone treatment in children with growth hormone deficiency and idiopathic short stature.

Isolated idiopathic growth hormone deficiency (GHD) and idiopathic short stature (ISS) can be difficult to distinguish, but the therapeutical consequences are different. In this report the data on final height of untreated and treated children with GHD and ISS are reviewed. Untreated GH-deficient individuals who underwent spontaneous puberty (22 male, 14 female patients) reached a mean final height of 4.7 SD (range 3.9 to 6.0) below the population's mean. If puberty was induced (19 male patients), mean final height SD score (SDS) was -3.1. Traditional regimens of GH administration (2-4 injections/wk) in 236 children (184 boys, 52 girls) with GHD and spontaneous puberty resulted in a final height SDS of -2.8 (range -1.5 to -4.7). In 190 children in whom puberty was induced (139 boys, 51 girls) mean final height was -1.6 (range - -1.1 to -2.4). The mean gain in final height SDS is therefore estimated at 1.5-2.0 in average cases, and 3.5 in extreme cases. Preliminary data suggest that on present regimens mean final height may approach target height. In untreated boys with ISS the mean final height was 2-5 cm lower than that predicted before puberty, whereas in girls it was almost equal to the prediction. After GH treatment the mean final height was 0.4-3.0 cm higher than the predicted adult height, which results in an average net gain in final height SDS of approximately 0.5-0.8 (3-5 cm).

Body Height↗
PubMed1996

Growth, growth hormone (GH)-binding protein, and GH receptors are differentially regulated by peak and trough components of the GH secretory pattern in the rat.

Body growth, GH secretory pattern, hepatic GH receptor (GHR), and plasma GH-binding protein (GHBP) levels are all sexually dimorphic in the rat. Male rats grow faster than females, and in GH-deficient animals, GH therapy is more effective when given in a pulsatile pattern rather than a continuous infusion. This contrasts with GHBP and hepatic GHR levels, which are lower in males than in females and raised by continuous but not pulsatile GH therapy. One possible explanation is that growth is primarily regulated by GH pulses, whereas GHR and GHBP are regulated mostly by the trough levels (which are lower in males than in females). To test this hypothesis directly, GH-deficient dwarf rats were given patterned iv infusions of hGH in which the relative contributions of the peak and trough components of the GH pattern were systematically varied, independently of dose, and their effects on weight and length gain, plasma GHBP, and hepatic GHR binding were measured. We found that the dose-response curves for GH given by pulsatile vs. continuous infusion were significantly nonparallel, and that growth was primarily stimulated by the pulsatile component of a mixed GH infusion pattern; doubling the GH dose by adding a continuous (c) infusion to a series of pulses (p) neither enhanced nor inhibited weight gain (36 micrograms hGH/day pulses (36p) vs. 36 micrograms hGH/day pulses + 36 micrograms hGH/day continuously (36p + 36c):0.9 +/- 0.2 g/day vs. 1.1 +/- 0.2 g/day), whereas doubling the GH dose by adding a pulsatile component significantly enhanced growth (72p:2.1 +/- 0.2 g/day, P < 0.01). Conversely, hepatic GHR and plasma GHBP levels were highly sensitive to the continuous element of the mixed infusion pattern and were totally unaffected by varying the pulsatile component over a wide range of doses. These results strongly suggest that growth and hepatic GHR/plasma GHBP respond differentially to the peak and trough components of the GH secretion pattern in the rat.

Animals↗
PubMed1996

Yearly stepwise increments of the growth hormone dose results in a better growth response after four years in girls with Turner syndrome. Dutch Working Group on Growth Hormone.

To optimize the growth promoting effect of growth hormone (GH), 65 previously untreated girls with Turner syndrome (TS), chronological age (CA) 2-11 yr, were randomized into 3 dosage regimen groups: A, B, and C, with a daily recombinant-human GH dose during 4 study years of 4-4-4-4, 4-6-6-6, and 4-6-8-8 IU/m2 b.s. The first GH dosage increase in groups B and C resulted in a significantly higher mean height velocity (HV) compared with constant dose group A. During the third year, when the dose was raised again only in group C, mean HV was significantly higher in groups B and C than in group A, and in group C compared with group B. In year 4 only group C mean HV remained significantly higher than group A. The pattern of change in HSDSCA (Dutch-Swedish-Danish Turner references) was identical; however, in year 4 mean delta HSDSCA in group B also remained significantly higher than group A. After 4 yr GH treatment, the following was determined. 1) The mean delta HSDSCA was significantly higher for groups B and C compared with group A, but not significantly different between groups B and C. 2) Although significantly higher compared with estimated values for untreated Dutch girls with TS, bone maturation of the GH treated girls was not significantly different between groups. 3) It was positively related with the degree of bone age (BA) retardation at start of study and negatively with baseline CA. 4) Both the modified Index of Potential Height (mIPHRUS) and a recently developed Turner-specific final height (FH) prediction method (PTSRUS), based on regression coefficients for H, CA, and bone age, showed significant increases in mean FH prediction, without significant differences between groups. PTSRUS values were markedly higher than the mIPHRUS values. Dose dependency could be shown for the area under the curve (AUC) for GH, but delta HSDSCA was not linearly related with AUC. Baseline GH binding protein (BP) levels were in 84% of the cases within the normal age range; the decrease in mean levels after 6 months GH was not significant. Mean insulin-like growth factor I (IGF-I) and IGFBP-3 plasma levels increased significantly, without significant differences between groups. delta HSDSCA during GH was dependent on IGF-I plasma levels at baseline and during the study period, beta-0.002 and beta-0.0004. Thus, a stepwise GH-dosing approach reduced the "waning" effect of the growth response after 4 yr treatment without undue bone maturation. FH prediction was not significantly different between treatment groups. Irrespective of the GH dose used, initiation of GH treatment at a younger age was beneficial after 4 yr GH when expressed as actual cm gained or as gain in FH prediction, but was not statistically significant when expressed as delta HSDSCA over the study period.

Body Height↗
PubMed1996

Growth curves of Dutch children with Down's syndrome.

Two thousand and forty-five observations on height and weight were collected from 295 healthy Dutch children with Down's syndrome. In a cross-sectional analysis, means and standard deviations were calculated per age-class, and subsequently smoothed, resulting in age references between 0 and 20 years. Each child contributed only once in every age class. In a subgroup in whom more than four measurements were available before puberty, quadratic regression functions were determined on the basis of the full data set, as well as for individual children separately (54 boys and 25 girls). The average coefficients of the individual regression functions were almost identical to the coefficients of the regression line through all data, indicating that the reference curve for the mean height based on cross-sectional analysis adequately represents longitudinal growth during childhood. Dutch children with Down's syndrome are taller than their US peers (P50 equals P75) but more than 2 SD shorter than normal Dutch children. Above the age of 10 years, the mean weight for height is above the P90 of normal children.

Adolescent↗
PubMed1996

Body weight in children with Turner syndrome treated with growth hormone.

OBJECTIVE: As overweight is a major concern in many children with Turner syndrome, we studied the effect of growth-promoting treatment with human growth hormone (hGH) on body weight indices. DESIGN: Longitudinal study of the effect of hGH on weight indices over time in a cohort of Turner girls of different ages. SUBJECTS: An index group of 199 hGH treated girls and a reference group of 569 untreated girls. METHODS: Turner-specific weight-for-age, weight-for-height and body mass index-for-age (BMI) values were computed. In order to take account of regression to the mean, we studied spontaneous changes of these variables in the reference group. References for spontaneous changes over 3, 6, 12 or 24 months were constructed. Observed changes in the index group were corrected by subtracting the expected spontaneous change. Corrected changes were compared between overweight, normal and underweight children. RESULTS: Treatment with hGH leads to a temporary decrease of weight indices during the first six months. This decreasing effect was not seen in overweight children. Treatment increases BMI in overweight children over 24 months, but not in normal or underweight children. BMI at start of hGH treatment did not modify long-term growth response. CONCLUSION: hGH treatment does not help to improve BMI in Turner syndrome children with a tendency to overweight.

Adolescent↗
PubMed1995

Testicular degeneration in three patients with the persistent müllerian duct syndrome.

UNLABELLED: The persistent müllerian duct syndrome, characterized by the presence of uterus and tubes in males, is a familial disorder due to defects of synthesis or action of anti-müllerian hormone, a Sertoli cell glycoprotein responsible for the regression of müllerian derivatives in normal male fetuses. Patients are normally virilized and testicular production of testosterone is normal. Both testes may be cryptorchid; alternatively, one may be descended into the inguinal canal or scrotum, together with the müllerian derivatives, a condition known as "hernia uteri inguinalis". We have recently observed three patients affected by the persistent müllerian duct syndrome who experienced progressive degeneration of testicular tissue. In two, functional testicular tissue was still present some months after birth, but deteriorated progressively later. In one patient, testicular tissue was already absent at birth, but the normal virilization of external genitalia indicated that testicular degeneration must have occurred late during fetal life, after the expected time of regression of male müllerian ducts. CONCLUSION: The high incidence of degeneration of testicular tissue in the persistent müllerian duct syndrome could be indirectly linked to anatomical abnormalities which could favour testicular torsion, known to induce testicular regression.

Chronic Disease↗
PubMed1995

Final height after long-term growth hormone treatment in Turner syndrome. European Study Group.

OBJECTIVES: To study final height after long-term growth hormone (GH) treatment in girls with Turner syndrome (TS). PATIENTS: One hundred fifty three patients with TS, participating in five European trials, were included. They started GH treatment in 1987-1989 at an age of 10 years or older. Mean age at start of treatment ranged between 11.7 and 14.6 years among countries and mean bone age between 9.4 and 11.8 years. Fourteen girls were lost to follow-up, leaving 139 for analysis. Most girls have now attained final height (FH), defined as a linear growth velocity (GV) of 4 mm/yr or less, measured over at least 6 months (group 1, n = 56), or near-FH, defined as a GV of 5 to 9 mm/yr (group 2, n = 22). Sixty-one girls were still growing 10 mm/yr or more. METHODS AND MAIN RESULTS: At the last measurement, mean (SD) height was 150.7 (4.9) cm in group 1 and 148.5 (5.1) cm in group 2. The differences between FH and projected final height based on extrapolation of the initial height-standard deviation score on Turner syndrome reference values, were 2.9 (3.8) and 3.0 (3.3) cm, respectively. The mean gain over the Bayley-Pinneau prediction of FH was 3.3 (3.9) cm in both groups. No significant differences between countries were found. The range of gains over projected height (-4.7 to 12.1 cm) was large, and 25% of gains were 5 cm or more. Gain over initial projection was strongly related to initial growth delay and to growth response during the first 2 years of treatment. A logistic regression model is presented that predicts gain of more than 5 cm with a positive predictive value of 62% and a negative predictive value of 84%. CONCLUSIONS: Long-term GH treatment in girls with TS, starting treatment at a relatively advanced age ( > 10 years) resulted in a modest mean gain in FH of 3 cm, with wide interindividual variation.

Adolescent↗