Biomedical subjects
Publications and source records attributed to B Boersma.
Two boys, aged 2 and 11 years, presented with fever and muscle weakness that resulted in respiratory insufficiency. A physical examination and additional tests confirmed the diagnosis 'myasthenia'. Acetyl cholinesterase-inhibitor therapy had a favourable effect. Myasthenia is a diagnosis that should be considered for every child presenting with muscle weakness of unknown origin.
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Childhood celiac disease may lead to a failure of statural growth. After institution of a gluten-free diet most patients exhibit catch-up growth. Catch-up growth is a remarkable phenomenon characterized by a supranormal height velocity. One of the hypothetical mechanisms of catch-up growth is that an increased activity of the somatotrophic axis is involved. In order to provide further insight in the physiology of catch-up growth, auxological and endocrine changes were prospectively studied in 28 children with newly diagnosed celiac disease. The results demonstrate a malnutrition-like state of the somatotrophic axis at the time of diagnosis and a rapid recovery of this axis towards normal functioning after institution of the gluten-free diet. Although several correlations between these endocrine alterations and auxological parameters were detected, it is questionable whether the endocrine changes are the driving force behind catch-up growth.
The myeloperoxidase-derived oxidant hypochlorous acid (HOCl) is thought to contribute to endothelial dysfunction, but the mechanisms underlying this inhibitory effect are unknown. The present study tested the hypothesis that HOCl and L-arginine (L-Arg) react to form novel compounds that adversely affect endothelial function by inhibiting nitric oxide (NO) formation. Using spectrophotometric techniques, we found that HOCl and L-Arg react rapidly (k = 7.1 x 10(5) m(-1) s(-1)) to form two major products that were identified by mass spectrometry as monochlorinated and dichlorinated adducts of L-Arg. Pretreatment of bovine aortic endothelial cells with the chlorinated L-Arg metabolites (Cl-l-Arg) inhibited the -induced formation of the NO metabolites nitrate (NO(3)(-)) and nitrite (NO(2)(-)) in a concentration-dependent manner. Preincubation of rat aortic ring segments with Cl-L-Arg resulted in concentration-dependent inhibition of acetylcholine-induced relaxation. In contrast, blood vessels relaxed normally to the endothelium-independent vasodilator sodium nitroprusside. In vivo administration of Cl-L-Arg to anesthetized rats increased carotid artery vascular resistance. A greater than 10-fold excess of L-Arg was required to reverse the inhibitory effects of Cl-L-Arg in vivo and in vitro. Reaction of HOCl with D-arginine (D-Arg) did not result in the formation of inhibitory products. These results suggest that HOCl reacts with L-Arg to form chlorinated products that act as nitric-oxide synthase inhibitors.
Soy and its isoflavones are associated with a reduced risk of chronic disease. The mechanisms of action of isoflavones include their roles as weak estrogens, inhibitors of tyrosine kinase-dependent signal transduction processes and as cellular antioxidants. Although estrogen receptor beta binds genistein with an affinity close to that of 17beta-estradiol, it remains to be determined whether it is a mediator of genistein's activity in vivo. Genistein's inhibition of protein tyrosine kinases is not limited to direct effect on these kinases, but may result from alteration in kinase expression. Genistein is not a particularly good scavanger of cellular oxidants; however, it reacts vigorously with the prooxidant hypochlorous acid, produced by neutrophils as part of the inflammatory response. The chlorinated isoflavones may have altered biochemical and biological effects compared to their parent compounds and may provide increased protection against inflammatory disease.
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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.
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.
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.
The fundamental frequency and jitter of the voice was measured by electroglottography in 71 children between the age of 7 and 15 years. In this series of children the fundamental frequency and jitter did not depend on the gender. The median (range) fundamental frequency was 244 (182-331) Hz in girls and 250 (205-293) Hz in boys. It decreased with increasing height (r = -0.59; P < 0.0005) and age (r = -0.57; P < 0.001). The median jitter ratio was 9.7 (1.6-33.3) in girls and 10.3 (2.0-4.3) in boys. The jitter ratio was negatively related to height (r = -0.31; P < 0.05), but not to age.
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BACKGROUND AND OBJECTIVE: Growth hormone treatment in children with idiopathic short stature (ISS) leads to growth acceleration in the first years, but the effect on final height is still poorly documented. We therefore studied the long-term effect of GH therapy in children with idiopathic short stature. DESIGN: We have treated 27 prepubertal children with ISS with recombinant human GH (rhGH) in an initial dosage of 2 IU/m2 body surface/day subcutaneously, which was doubled either after the first year if the height velocity increment was less than 2 cm/year, or thereafter if height velocity fell below the P50 for bone age. Growth and bone maturation of the treatment group (ISS group, n = 21) were compared to those of an untreated control group with ISS (ISS controls, n = 27) and of a group of rhGH treated children with isolated GH deficiency (GHD group, n = 7). RESULTS: In 9 patients of the ISS group still on treatment, height standard deviation score (HSDS) for chronological age increased from -3.8 +/- 0.7 to -2.3 +/- 0.9 (mean +/- standard deviation) over 6 years, while in matched ISS controls HSDS for age did not change. HSDS for age in the GHD group increased from -3.9 +/- 0.6 to -1.8 +/- 0.7 after 4 years, significantly more than the ISS group. Bone maturation was accelerated in the ISS and GHD groups. HSDS for bone age and predicted adult height did not change in either group. Final height in 12 children of the ISS group was -2.6 +/- 1.0 SDS. In the untreated controls final height was similar. A low integrated GH concentration over 24 hours, a low GH peak to provocative stimuli, and minimal initial BA delay predicted a favourable outcome. CONCLUSION: rhGH treatment in this group of children with idiopathic short stature did not increase average final height. Part of the heterogeneity of the response can be attributed to the variation in endogenous GH secretion and initial bone age delay.
Catch-up growth of 26 children with growth hormone deficiency during four years of growth hormone treatment, which was started young (< 3 years), was compared with that of 16 children with coeliac disease on a gluten free diet. In children with growth hormone deficiency mean (SD) height SD score increased from -4.3 (1.8) to -1.9 (1.4) and in patients with coeliac disease from -1.8 (0.9) to -0.1 (0.8). Height SD score after four years correlated positively with injection frequency and height SD score at start of treatment in children with growth hormone deficiency. All patients with coeliac disease reached a height above -2 SD scores after four years, while the height of 26% of children with growth hormone deficiency on daily injections and of 86% of children on 2 or 4 injections/week was still below -2 SD scores. In patients with growth hormone deficiency on daily injections with an initial height SD score between -2 and -4 catch-up was similar to that of patients with coeliac disease with a comparable initial height deficit. Growth hormone deficient children with an initial height SD score < -4 did not reach full catch-up growth within four years. In conclusion, catch-up growth in early treated children with growth hormone deficiency over four years is adequate provided that daily injections are given and the initial height SD score is not less than -4.
Body proportions were studied in 31 girls with constitutional tall stature during treatment with 200 micrograms ethinyl oestradiol per day continuously, combined with 5-10 mg medroxyprogesterone on the first 10 days of each month. Their mean (+/- SD) predicted adult height was 186.0 (+/- 4.0) cm. At the start of therapy, leg length (LL) standard deviation score (SDS) (3.8 +/- 0.7) was significantly greater than the sitting height (SH) SDS (2.3 +/- 1.1). During therapy, the mean sitting height increased by 2.9 cm, in contrast to an increment of only 0.8 cm for LL. The SDS of the ratio between SH and LL remained below zero. The expected gain without therapy, assuming a stable SDS position over time, was 5.4 cm for SH and 4.4 cm for LL, significantly more than the observed gains. In conclusion, tall girls have relatively long legs. Oestrogen therapy leads to an almost complete stop of leg growth, while the growth of the trunk is reduced to a lesser extent. This selective inhibition results in a trunk/leg ratio which is closer to, though still significantly different from that of normal girls.
The growth pattern of 28 girls and 32 boys with celiac disease was analyzed up to the ages of 10 and 12 years, respectively. Fifty-four patients (90%) were diagnosed before 4 years of age and six patients (10%) between 5 and 9 years of age. At diagnosis, 18 of 60 patients (30%) had a height SD score below -2.0, and 45 of 59 patients (76%) had a weight-for-height below the median. The mean height SD score showed increasing growth retardation in the year before diagnosis, relatively quick catch-up growth in the year after diagnosis, and complete catch-up in 2-3 years. Mean weight-for-height showed a progressive decrease 12-18 months before diagnosis, increased to a maximum at the end of the first year of therapy, and returned to normal 15 months after dietary treatment. Independent of age at diagnosis, initial degree of wasting, diagnostic delay, and strictness of gluten-free diet, catch-up growth was complete in this group of patients who were diagnosed before 9 years of age.
Celiac disease may lead to various degrees of growth retardation. In general, catch-up growth is completed in the first 2 years after the start of therapy. A mathematical model for catch-up growth in celiac disease can be useful as a reference to which the growth pattern observed during treatment of other conditions can be compared. In this study we performed a non-linear regression analysis on individual growth data of 16 celiac disease patients using a monomolecular growth function. The goodness of fit was significant in all cases (p < 0.05), which illustrates that this function adequately describes catch-up growth in individuals with celiac disease. From the individual models we have composed a cross-sectional curve and a longitudinal description of the pattern of catch-up growth for the entire population.