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T Vulsma

Publications and source records attributed to T Vulsma.

At least 55 records · Page 3Linked to original sources
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

Type II and type III deiodinase activity in human placenta as a function of gestational age.

Thyroid hormones are essential for fetal development. T4 can be activated by type I (ID-I) and type II (ID-II) iodothyronine deiodinase or inactivated by type III deiodinase (ID-III). The influence of placental ID-II and ID-III on the regulation of fetal thyroid hormone levels was investigated. Using [125I]T4 and [125I]T3, respectively, ID-II and ID-III activities were measured in homogenates of normal human placentas from 6-43 weeks gestational age and in placentas from five term neonates with a total thyroid hormone synthesis defect. ID-II and ID-III activities related to protein or DNA concentration decreased and total placental ID-III activity increased significantly during pregnancy, whereas the increase in total placental ID-II activity was not significant. Absolute placental ID-II activity was approximately 200 times lower than ID-III activity at all gestational ages. Therefore, fluctuations in ID-II activity were not likely to have a significant influence on fetal thyroid hormone concentrations, but may play a role in the regulation of intraplacental T3 generation. The high ID-III activity most likely influences the thyroid hormone economy of the fetus. Severely hypothyroid newborns showed strongly decreased serum T4 levels, but serum T3 and placental ID-III activities were similar to those in euthyroid newborns. These results suggest that placental ID-III activity is regulated by serum T3, but not by serum T4.

Female↗
PubMed1995

Identification of five novel inactivating mutations in the human thyroid peroxidase gene by denaturing gradient gel electrophoresis.

Thyroid peroxidase (TPO) is the key enzyme in the synthesis of thyroid hormones. Defects in the TPO gene are reported to be the cause of congenital hypothyroidism due to a Total Iodide Organification Defect (TIOD). This type of defect, where iodide taken up by the thyroid gland cannot be oxidized and bound to protein, is the most common hereditary inborn error causing congenital hypothyroidism in the Netherlands. Denaturing Gradient Gel Electrophoresis (DGGE) of PCR amplified genomic DNA was used to screen for mutations in the TPO gene of TIOD patients from nine apparently unrelated families, and seven different mutations were detected. Three frameshift mutations were found: a 20 bp duplication in exon 2, a 4 bp duplication in exon 8, and an insertion of a single nucleotide (C) at pos. 2505 in exon 14. In addition, four single nucleotide substitutions were identified: one single-base mutation resulted in a premature termination codon (C-->T at pos. 1708 in exon 10), two single-base substitutions changed an amino acid in highly conserved regions of the gene (Tyr-->Asp in exon 9 and Glu-->Lys in exon 14). The fourth single-base mutation located at the exon 10/intron 10 border altered a conserved Gly into Ser and could also affect splicing. Nine TIOD patients from five families were compound heterozygotes and six patients from four families were homozygous for one of the mentioned mutations in the TPO gene.

Base Sequence↗
PubMed1995

Treatment with two growth hormone regimens in girls with Turner syndrome: final height results. Dutch Growth Hormone Working Group.

In 1987 a multicentre trial of recombinant human growth hormone (GH) was started in girls with Turner syndrome. Fifty-four patients were randomly assigned to receive GH, 8 IU/m2 3 times/week (group 1), or 4 IU/m2 6 times/week (group 2). In addition, the 35 patients older than 12 years received ethinyloestradiol, 100 ng/kg body weight/day, and after 2 years GH therapy was increased to 6 IU/m2 6 times/week. Recombinant human GH treatment was stopped when the height increment during the previous 6 months of treatment was less than 0.5 cm. Treatment has so far been stopped in 48 patients: treatment was stopped early in 2 patients due to lack of motivation, 1 patient died suddenly and the treatment protocol was completed in 45 patients. The last height measurement obtained, which was considered as (near) final height, was 152.3 +/- 5.3 cm (mean +/- SD) in these patients, which is higher (p < 0.001) than the adult height of 147.0 +/- 6.3 cm reported in 63 untreated adult Dutch patients with Turner syndrome. No differences in outcome were found between the two dose regimens.

Body Height↗
PubMed1994

Motor and cognitive development in children with congenital hypothyroidism: a long-term evaluation of the effects of neonatal treatment.

Although neonatal thyroid screening programs have been of value in preventing cerebral damage, it is still controversial whether patients with congenital hypothyroidism achieve normal motor and cognitive skills. We studied the motor and cognitive skills of 72 children with early-treated congenital hypothyroidism and 35 control subjects at the ages of 7 1/2 and 9 1/2 years. The relative influence of cause, blood thyroxine concentration at the time of screening, and age at the start of thyroxine replacement therapy on motor and cognitive development was investigated. Despite having received treatment at a mean age of 23 days, children with low neonatal thyroxine concentrations (< 50 nmol/L) at screening, particularly children with thyroid agenesis, had significant motor problems and borderline intelligence scores as late as 9 1/2 years of age. Balance and gross motor functions seemed to decline between 7 1/2 and 9 1/2 years of age, whereas language and memory functions seemed to be maintained. Significant correlations between the start of therapy and both motor scores and performance IQ scores at the age of 7 1/2 years in children with severe hypothyroidism show the importance of early treatment for these patients.

Age Factors↗
PubMed1994

A 20-basepair duplication in the human thyroid peroxidase gene results in a total iodide organification defect and congenital hypothyroidism.

In this study we present the molecular basis of a total iodide organification defect causing severe congenital hypothyroidism. In the thyroid gland of the patient, thyroid peroxidase (TPO) activity and the iodination degree of thyroglobulin were below detection limits, and no TPO messenger ribonucleic acid was detectable by Northern blot analysis. Denaturing gradient gel electrophoretic analysis of the TPO gene of the patient revealed a homozygous mutation in exon 2. Sequence analysis showed the presence of a 20-basepair duplication, 47 basepairs down-stream of the ATG start codon. This duplication generates a frame shift, resulting in a termination signal in exon 3, compatible with the complete absence of TPO. Both parents of the patient are heterozygous for the same duplication, confirming the recessive mode of inheritance of the mutation.

Base Composition↗
PubMed1993

[Evaluation of a decade of neonatal screening for congenital hypothyroidism in The Netherlands].

OBJECTIVE: Evaluation of the Dutch screening programme for congenital hypothyroidism (CH). DESIGN: Descriptive. SETTING: Nationwide. METHODS: Data on the screening were obtained from the administration body for vaccination and screening results, laboratories and paediatricians to whom infants with positive screening values were referred, during the period from January 1st, 1981 to December 31st, 1990. RESULTS: Of all live births in the Netherlands, 99.5% (1,797,719) were screened for CH. During the study period, 10,165 children (0.57% of all screened infants) were referred. Of the referred children, 529 had primary CH and 53 had congenital thyrotropin deficiency syndrome (CTDS). The prevalences of primary CH and CTDS are 1:3,400 and 1:25,000, respectively. The sensitivity of the programme with respect to detection of primary CH and CTDS was 99% and 74%, respectively. For all forms of CH combined, the specificity of the programme was 99% and the positive predictive value 6%. The positive predictive value was especially low in the group of infants with low T4 and normal thyrotropin values. One of the goals of the programme is to realise the start of treatment in all patients before they reach the age of three weeks. Before the screening programme came into being, the cumulative proportion of patients treated on the 21st day was 6%. After the beginning of the programme, the proportion increased to 54%. In screened patients with a severe form of CH it is currently 72%. CONCLUSION: The screening programme has made a substantial and important contribution to early and effective identification of patients with CH. A number of measures to decrease the number of false-positive results have been taken and others are at present being investigated. Although patients are now treated much earlier than before the programme started, substantial improvement in this respect is still possible. This can only be achieved by a collective effort of performers of the heel puncture, laboratories, administration body for vaccination and screening results, general practitioners and pediatricians.

Congenital Hypothyroidism↗
PubMed1993

Results of long-term therapy with growth hormone in two dose regimens in Turner syndrome. Dutch Growth Hormone Working Group.

Girls with Turner syndrome were divided according to age (group A 6-12 years, and group B 12-19 years) and human growth hormone (GH) dose regimen (A1 and B1, three injections/week; A2 and B2, six injections/week). All groups responded to GH, 24 IU/m2/week, with an increase in height velocity, though in the older girls, the response was comparatively poor. Therefore, the dose regimens in groups B1 and B2 were increased to 36 IU/m2/week given as six injections in both groups. This change resulted in an increase in height velocity only in group B1. During the first 2 years only, the height velocity was greater in group A2 than group A1. The conclusion is that a regimen of six injections/week is more effective than one of three injections/week in terms of initial height gain and change in predicted adult height. In girls with Turner syndrome aged over 16 years, GH therapy has no significant effect.

Adolescent↗
PubMed1993

Effects of pre- and postnatal exposure to chlorinated dioxins and furans on human neonatal thyroid hormone concentrations.

Animal studies have shown that dioxins influence plasma thyroid hormone concentrations. To investigate the effect of chlorinated dioxins and furans on thyroid hormone concentrations in humans, we studied 38 healthy breast-fed infants. The study population was divided into two groups according to the dioxin concentrations in milk fat of their mothers. Blood samples were taken at birth and at the ages of 1 and 11 weeks. At birth a tendency to higher total thyroxine (tT4) concentrations was found in the high exposure group. At the ages of 1 and 11 weeks the increase of mean tT4 concentrations and tT4/thyroxine-binding globulin ratios in the high exposure group reached significance as compared to the low exposure group. At birth and 1 week after birth, mean thyrotropin (TSH) concentrations were similar in both groups, but at the age of 11 weeks the mean TSH concentrations were significantly higher in the high exposure group. We postulate that the observed plasma tT4 elevation in infants exposed to dioxins before and after birth is the result of an effect on the thyroid hormone regulatory system.

Adult↗
PubMed1993

Thyroxine administration to infants of less than 30 weeks' gestational age does not increase plasma triiodothyronine concentrations.

Very preterm infants (less than 30 weeks' gestational age) were treated with thyroxine in three different dosage schemes: 10, 8 and 6 micrograms.kg-1 birthweight.day-1 during the first 6 weeks of life. The aim was to prevent transient hypothyroxinemia of the preterm infant. Plasma levels of thyroxine, free thyroxine, triiodothyronine, reverse triiodothyronine, thyroxine-binding globulin and thyrotropin were measured weekly. Thyroxine administration increased thyroxine and free thyroxine levels most properly in the 8-micrograms supplementation group. It did not result in a change in plasma triiodothyronine levels. Levels of reverse triiodothyronine increased in relation to the thyroxine dosage. Thyrotropin secretion was suppressed in the 6- and 8-micrograms groups during the first 2 weeks, while in the 10-micrograms group suppression lasted 4 weeks. No clinical adverse effects of thyroxine administration were seen. We conclude that 8 micrograms thyroxine.kg-1 birthweight.day-1 for 6 weeks prevents transient hypothyroxinemia. The finding that plasma triiodothyronine concentrations are not influenced by thyroxine administration suggests a specific maturation process in the deiodination of thyroxine.

Aging↗
PubMed1992

Use of amiodarone during pregnancy.

UNLABELLED: Five cases are studied in which amiodarone (AM) was given during pregnancy, in two of them also during the breast feeding period, to estimate the risks for adverse effects. We measured the concentrations of AM and its major metabolite desethylamiodarone (DEA) in maternal plasma, cord plasma, infant plasma, placental tissue and breast milk and the thyroid hormones were measured in maternal and neonatal serum. Also, the neonates were examined for AM-associated adverse effects over a period varying from 8 months up to 5 years. We observed a limited maternal-fetal transfer of AM and DEA, while the concentration of DEA in placental tissue is relatively high. Considerable amounts of AM and DEA were present in breast milk. One infant appeared to be hypothyroid, detected by the neonatal thyroid screening. He was treated with triiodothyronine for weeks, until it was clear that the thyroid dysfunction was resolved. The other infants had normal screening results. No effect of the AM medication was observed on growth, liver function or cornea and skin. IN CONCLUSION: although pregnancy and lactation are no absolute contraindications for use of AM, special precautions are necessary. It is unavoidable that in some cases the pregnant mother, and especially her infant, becomes hypothyroid. AM has to be administered in the lowest possible dose, and the maternal and neonatal thyroid function must be controlled as long as the exposure to AM lasts.

Amiodarone↗
PubMed1991

The role of serum thyroglobulin concentration and thyroid ultrasound imaging in the detection of iodide transport defects in infants.

When discovered by neonatal screening, a thyroid dyshormonogenesis is usually not recognized as a goitre. Especially a total iodide transport defect can easily be misclassified as thyroid agenesis, since radionuclide imaging cannot visualize the thyroid. We present the only iodide transport defect ever discovered in the Netherlands, the 35th reported in the literature, and the first one found exclusively as a result of neonatal screening. We demonstrate that iodide transport defects, in common with organification and deiodinase defects, can be distinguished from thyroid dysgenesis by demonstrating a normal or enlarged thyroid ultrasound image, and especially by measuring very high serum thyroglobulin levels (above 1000 pmol/l). In the presented case, an iodide-123 saliva-to-serum ratio near unity completed the etiologic classification. Measurement of serum thyroglobulin levels, in combination with thyroid ultrasound imaging, will improve the early identification of hereditary types of congenital hypothyroidism, and especially iodide transport defects, in patients found by neonatal thyroid screening.

Biological Transport↗
PubMed1989

Maternal-fetal transfer of thyroxine in congenital hypothyroidism due to a total organification defect or thyroid agenesis.

The fact that neonates who subsequently have severe hypothyroidism have no evidence of the condition at birth suggests the possibility of the placental transfer of thyroid hormones. Recent studies have demonstrated the existence of such transfer in hypothyroid rats. To determine whether there is a transfer of thyroxine (T4) from mother to fetus, we studied 25 neonates born with a complete inability to iodinate thyroid proteins and therefore to synthesize T4. This total organification defect is an autosomal recessive disorder with an incidence of approximately 1 in 60,000 neonates in the Netherlands. In the cord serum of affected neonates, T4 levels ranged from 35 to 70 nmol per liter. Since these patients were unable to produce any T4, the T4 must have originated in their mothers. The estimated biologic half-life of serum T4 was 3.6 days (95 percent confidence interval, 2.7 to 5.3). In 15 neonates with thyroid agenesis, the serum levels and the disappearance kinetics of T4 were the same as those in the neonates with a total organification defect, suggesting that in these infants, the T4 also had a maternal origin. We conclude that in infants with severe congenital hypothyroidism, substantial amounts of T4 are transferred from mother to fetus during late gestation.

Congenital Hypothyroidism↗
PubMed1989

Antibodies to 'second colloid antigen.' A study on the prevalence in sporadic forms of congenital hypothyroidism.

Antibodies against the so called 'second colloid antigen' (CA2 antibodies) occurred in 51% of the mothers of hypothyroid children detected by screening for neonatal congenital hypothyroidism in Quebec (N = 49) and in The Netherlands (N = 26). In The Netherlands where corresponding neonatal serum was available, 31% (8 of 26) of the infants with congenital hypothyroidism were positive for antibodies against the second colloid antigen. When during follow-up, 3 to 5 years after diagnosis, the mothers and their children were investigated, 46% (7 of 15) of the mothers were positive for antibodies against the second colloid antigen, whereas 29% (4 of 14) of the hypothyroid children were also positive. Various control groups did not show more than a 12% positivity. This presence of thyroid-reactive antibodies in a proportion of the hypothyroid children 3 to 5 years after diagnosis is not compatible with a mere transplacental passage; it indicates that the antibodies must be produced by the mothers and by the children themselves. We conclude that a thyroid autoimmune response occurs in a considerable part of infants with congenital hypothyroidism and their mothers and that this immune response seems to persist in both of them for years.

Adult↗
PubMed1986

[Congenital hypothyroidism. Current viewpoints and developments].

Since 1978 neonatal screening on congenital hypothyroidism (CHT) is performed in The Netherlands. A combined T4 and TSH determination is used. This creates the possibility to detect secondary and tertiary hypothyroidism. The number of false-positive cases is relatively high. This number decreases by adjusting the method of screening. Recent studies show a CHT incidence of 1:2100 newborns. In about 25% of these cases the CHT appears to be transient. Proceeding from the screening on CHT several investigations presented in this review are in progress.

Congenital Hypothyroidism↗