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Biomedical subjects

E M Ritzén

Publications and source records attributed to E M Ritzén.

At least 19 recordsLinked to original sources
PubMed2002

Estrogen receptor-alpha and -beta are expressed throughout postnatal development in the rat and rabbit growth plate.

Estrogen regulates skeletal growth and promotes epiphyseal fusion. To explore the mechanisms underlying these effects we investigated the expression of estrogen receptor-alpha (ERalpha) and -beta (ERbeta) in rat and rabbit growth plates during postnatal development, using immunohistochemistry. Immunoreactivity for ERalpha and ERbeta was observed in resting zone and proliferative zone chondrocytes at all ages studied for both rat (7, 14, 28 and 70 days of age) and rabbit (1, 7, 28 and 120 days of age). In the rat distal humerus and the rabbit proximal tibia, expression of both receptors in the hypertrophic zone was minimal at early ages, increasing only at the last time point prior to epiphyseal fusion. Expression was rarely seen in the hypertrophic zone of the rat proximal tibia, a growth plate that does not fuse until late in life. Therefore, we conclude that ERalpha and ERbeta are both expressed in the mammalian growth plate. The temporal and anatomical pattern suggests that ER expression in the hypertrophic zone in particular may play a role in epiphyseal fusion.

Aging↗
PubMed2001

Prenatal dexamethasone treatment of fetuses at risk for congenital adrenal hyperplasia: benefits and concerns.

Virilization due to congenital adrenal hyperplasia (CAH) can effectively be prevented or diminished by prenatal dexamethasone given to the mother. This treatment, which should only be considered in families with a previous child with a virilizing form of the disease, has to start already at 6-7 weeks of gestation. Thus, the treatment has to be given 'blindly' to all mothers at risk until the diagnosis of an affected female can be ascertained by analysis of DNA from a chorionic villous biopsy, which cannot be performed until the 10th week. Since CAH is inherited as an autosomal recessive disease and only affected girls benefit from the treatment, seven out of eight fetuses are treated unnecessarily. This makes it especially important to monitor possible side effects. Adverse effects on brain and kidneys have been shown in animals exposed to large doses of dexamethasone during the second trimester. Too few follow-up human studies are reported to date to allow definite conclusions on possible side effects in man. Therefore, treatment should be done within controlled clinical studies.

Adrenal Hyperplasia, Congenital↗
PubMed2001

Endocrine dysfunction in Prader-Willi syndrome: a review with special reference to GH.

Prader-Willi syndrome is a genetic disorder occurring in 1 in 10,000-16,000 live-born infants. In the general population, approximately 60 people in every 1,000,000 are affected. The condition is characterized by short stature, low lean body mass, muscular hypotonia, mental retardation, behavioral abnormalities, dysmorphic features, and excessive appetite with progressive obesity. Furthermore, morbidity and mortality are high, probably as a result of gross obesity. Most patients have reduced GH secretory capacity and hypogonadotropic hypogonadism, suggesting hypothalamic-pituitary dysfunction. Replacement of GH and/or sex hormones may therefore be beneficial in Prader-Willi syndrome, and several clinical trials have now evaluated GH replacement therapy in affected children. Results of GH treatment have been encouraging: improved growth, increased lean body mass, and reduced fat mass. There was also some evidence of improvements in respiratory function and physical activity. The long-term benefits of GH treatment are, however, still to be established. Similarly, the role of sex hormone replacement therapy needs to be clarified as few data exist on its efficacy and potential benefits. In summary, Prader-Willi syndrome is a disabling condition associated with GH deficiency and hypogonadism. More active treatment of these endocrine disorders is likely to benefit affected individuals.

Adolescent↗
PubMed2000

Androgen and estrogen stimulation of ornithine decarboxylase activity in mouse kidney.

In the present work, the activity of mouse renal ornithine decarboxylase (ODC) from CBA female mice was used as a biological marker to detect (anti)androgenic activity of different groups of endocrine disruptors and steroids. Daily injections of testosterone or dihydrotestosterone (DHT) into 60 day old female mice for 4 days increased renal ODC activity in a dose-dependent manner that reached up to 100-fold (testosterone) or 250-fold (DHT) above the baseline when the highest dose, 200 microg/mouse, was used. Administration of flutamide concurrently with testosterone (75 microg/mouse) caused a potent decrease of ODC induction in a dose-dependent manner, suppressing the enzyme activity at the doses of 0.1 and 0.5 mg/mouse by about 88 and 95%, respectively. In contrast, estradiol at the doses of 0.5 and 1 mg/mouse induced a significant stimulation of renal ODC activity in a dose-dependent manner when it was given alone or in combination with testosterone. Using a sensitive increase in ODC activity in response to androgens as an end point, we did not detect an antiandrogenic effect of several antiandrogens, such as cyproterone acetate, spironolactone, p,p'DDE and vinclozolin. Also, none of these antiandrogens were able to change the basal level of renal ODC activity, with the exception of cyproterone acetate that at a dose of 0.1 mg/mouse stimulated ODC activity. The data obtained suggest that mouse renal ODC from CBA females is not strictly androgen-specific and cannot be used for estimation of antiandrogenic effects of compounds having an affinity to different types of receptors.

Androgen Antagonists↗
PubMed2000

Eating behavior in Prader-Willi syndrome, normal weight, and obese control groups.

OBJECTIVE: Hyperphagia in Prader-Willi syndrome (PWS) is hypothesized to be due to hypothalamic dysfunction; thus the study of individuals with PWS might illustrate how hypothalamic dysfunction affects eating behavior. The aim of this study was to document the microstructure of the eating behavior in patients with PWS and to compare it with that of members of obese and normal weight control groups of the same age. STUDY DESIGN: Nine subjects with PWS (age, 10 +/- 4 years), 20 normal weight subjects (age, 12 +/- 3 years), and 20 obese subjects (age, 12 +/- 4 years) were served an excess lunch meal (hash) on a hidden scale built into a table and connected to a computer. The plate of food is placed on top of the scale, and when the food is eaten, the change in food weight is registered continuously. An eating curve is displayed online. After the meal, the eating data are fitted to a polynomial, and the computer calculates the amount of food eaten, time of consumption, eating rate (initial and total), and rate of deceleration. RESULTS: Subjects with PWS were found to have a longer duration of eating (P =.04) and a slower initial eating rate (P =. 01) compared with members of both obese and normal weight groups. In subjects with PWS, 56% of the eating curves were non-decelerating (linear or accelerating) compared with 10% of the normal weight group and 30% of the obese group (P =.02). CONCLUSION: The microstructure of the eating behavior in subjects with PWS differs from that of members of obese and normal weight control groups. Thus the eating behavior found in subjects with PWS might be due to decreased satiation rather than increased hunger.

Adolescent↗
PubMed2000

How can molecular biology contribute to the management of congenital adrenal hyperplasia?

The most common form of congenital adrenal hyperplasia is due to a deficiency of 21-hydroxylase (21OHD) activity and is caused by a mutation in the CYP21 gene. By genotyping patients, new and important information can be gained, including presence or absence of 21OHD in borderline cases, determining the severity of disease and identifying heterozygote carriers. Current management of patients with 21OHD involves administering sufficient glucocorticoids to suppress excess adrenal androgen secretion, but not so much that bone growth and mineralization are impaired. New management strategies have been proposed and include administering only substitution doses of corticosteroids and counteracting side-effects by administering an anti-androgen and aromatase inhibitor. Adrenalectomy has also been proposed. Further investigation into these approaches is necessary.

Adrenal Hyperplasia, Congenital↗
PubMed2000

Characterisation of novel missense mutations in the GH receptor gene causing severe growth retardation.

Two Swedish brothers, 2.5 and 4 years of age, were found to fulfil all the clinical and laboratory characteristics of Laron's syndrome. They were shown to have unique missense mutations in the GH receptor gene. Both of their parents were of normal height, but they both separately carried one of the identified gene alterations. A molecular model of the first receptor alteration suggests that a collapse in three-dimensional receptor structure most likely contributed to the GH insensitivity in these patients.

Amino Acid Sequence↗
PubMed1999

Growth hormone treatment increases CO(2) response, ventilation and central inspiratory drive in children with Prader-Willi syndrome.

UNLABELLED: We studied whether the beneficial effects of growth hormone (GH) treatment on growth and body composition in PWS are accompanied by an improvement in respiratory function. We measured resting ventilation, airway occlusion pressure (P(0.1)) and ventilatory response to CO(2) in nine children, aged 7-14 years, before and 6-9 months after the start of GH treatment. During GH treatment, resting ventilation increased by 26%, P(0.1) by 72% and the response to CO(2) by 65% (P < 0.002, <0.04 and <0.02, respectively). This observed increase in ventilatory output was not correlated to changes in body mass index. CONCLUSION: Treatment of children with Prader-Willi syndrome (PWS) seems to have a stimulatory effect on central respiratory structures. The observed increase in ventilation and inspiratory drive may contribute to the improved activity level reported by parents of PWS children during growth hormone therapy.

Adolescent↗
PubMed1999

Beneficial effects of dietary supplementation in a disorder with defective synthesis of cholesterol. A case report of a girl with Smith-Lemli-Opitz syndrome, polyneuropathy and precocious puberty.

In 1993 the Smith-Lemli-Opitz (SLO) syndrome, known as a malformation syndrome characterized by certain stigma, turned out to be a metabolic disease with a defect in the last step of cholesterol biosynthesis. This led to the possibility of identifying affected individuals by biochemical methods and of increasing understanding of pathogenic mechanisms. Hopes of influencing the effects of the metabolic defect by dietary supplementation were raised and reports with some benefits of treatment have been published. This is a report of a 12-y-old girl with the SLO syndrome in an apparently progressive form. In addition to typical signs and well-known symptoms she has a verified polyneuropathy and precocious puberty. She has been treated with cholesterol and bile acids for 3 y, during which time the progressive course has been arrested. A notable effect has been the improvement of her polyneuropathy, verified by measurement of nerve conduction velocities. Possible mechanisms involved in the pathogenesis of her precocious puberty are discussed.

Bile Acids and Salts↗
PubMed1999

Five years of growth hormone treatment in children with Prader-Willi syndrome. Swedish National Growth Hormone Advisory Group.

The authors have followed 18 prepubertal children (3-12 years of age) with Prader-Willi syndrome during 5 years of growth hormone (GH) treatment. Initially, all the children participated in a randomized, controlled GH trial, conducted to assess the effects of GH treatment on growth, body composition and behaviour. GH was administered to group A (n = 9) at a dose of 0.1 IU/kg/day (0.033 mg/kg/day) for 2 years. Group B (n = 9) was untreated for the first year, but the children were given GH at a dose of 0.2 IU/kg/day (0.066 mg/kg/day) during the second year. Thereafter, all children stopped GH treatment for 6 months and were then restarted with GH at a dose of 0.1 IU/kg/day (0.033 mg/kg/day). During the first year of GH treatment, there was a dramatic increase in height SDS in both groups. The attained height percentile was maintained during the continued GH treatment. Five years after the start of GH treatment, mean height SDS is still above average for age. Four children have reached final height, all within 2 SD of target height. During the first year of GH treatment, body mass index (BMI) SDS decreased significantly from 3.0 to 1.5 SDS in group A and from 2.8 to 1.2 SDS in group B, but it increased again during the 6-month period without treatment. Following the restart of GH treatment, BMI SDS has stabilized at 1.7 SDS for group A and 2.5 SDS for group B. In 16 of 18 patients, fasting insulin, glucose and the A1c fraction of glycosylated haemoglobin remained within normal ranges during 5 years of GH treatment. Following a period of rapid weight gain, two children have developed non-insulin-dependent diabetes mellitus. Glucose homeostasis returned to normal when GH treatment was withdrawn. In conclusion, GH treatment has a proven favourable effect on growth and body composition in patients with Prader-Willi syndrome. Treatment should be individualized, and close surveillance of glucose homeostasis is needed, especially if the patient is severely obese.

Adolescent↗
PubMed1999

Growth hormone treatment of children with Prader-Willi syndrome: effects on glucose and insulin homeostasis. Swedish National Growth Hormone Advisory Group.

Insulin and glucose homeostasis have been studied during growth hormone (GH) treatment in 19 prepubertal children with Prader-Willi syndrome (PWS) and compared with 11 healthy prepubertal obese children. Before treatment, insulin levels in children with PWS were lower (p < 0.01) than in healthy obese children. During GH treatment, fasting insulin levels increased in children with PWS (p < 0.001). Glucose levels were similar for PWS and obese children before treatment. Children with PWS showed a slow glucose disappearance rate (k = 1.7%) which deteriorated (k = 1.3%, p < 0.001) during GH treatment. HbA1c and fasting glucose levels remained normal. Thus, GH treatment of children with PWS resulted in increased insulin blood levels, unchanged fasting glucose and HbA1c but decreased glucose elimination rate after an intravenous glucose test. However, the observed dose-dependent increase in insulin levels during GH treatment, that reached supranormal concentrations in 6/19 patients, and the occurrence of NIDDM in 1 patient during follow-up suggest that close surveillance and low doses of GH should be applied, especially if the PWS patient is very obese.

Blood Glucose↗
PubMed1999

Management of males with 45,X/46,XY gonadal dysgenesis.

Males with the 45,X/46,XY karyotype and malformations of the external genitalia carry an increased risk of developing germ cell neoplasia of the gonads. We have studied gonadal tissue from 10 individuals, 0.3-17 years of age, with a male phenotype and either hypospadias and/or cryptorchidism. Four patients, 0.3-15 years of age, had carcinoma in situ, 1 boy had Sertoli-cell-only pattern and the remainder prepubertal histology. Gonadoblastoma or invasive carcinoma was not found. On the basis of our current knowledge we propose a strategy for management and follow-up of these boys in order to detect possible premalignant histological changes early and prevent development of a gonadal tumour.

Adolescent↗
PubMed1999

Demonstration of estrogen receptor-beta immunoreactivity in human growth plate cartilage.

Estrogens affect longitudinal bone growth through their action on endochondral bone formation. Two estrogen receptors are known, the classical estrogen receptor-alpha (ER alpha), newly demonstrated in human growth plate cartilage, and a recently cloned estrogen receptor-beta (ER beta). The present study aimed to localize a possible expression of ER beta protein in human growth plates. Tissue samples were obtained from tibial and femoral growth plates in four female pubertal patients undergoing epiphyseal surgery. Immunohistochemistry, using two different ER beta-specific antibodies, demonstrated positive staining for ER beta in hypertrophic epiphyseal chondrocytes from all patients. No staining was noted in resting or proliferative chondrocytes. These data suggest that in addition to ER alpha, human epiphyseal chondrocytes also express ER beta. The physiological role of ER beta in the regulation of longitudinal bone growth in humans remains to be elucidated.

Adolescent↗
PubMed1999

Failure of cortisone acetate treatment in congenital adrenal hyperplasia because of defective 11beta-hydroxysteroid dehydrogenase reductase activity.

Congenital adrenal hyperplasia in children is often treated with cortisone acetate and fludrocortisone. It is known that certain patients with congenital adrenal hyperplasia require very high substitution doses of cortisone acetate, and a few patients do not respond to this treatment at all. A patient with 21-hydroxylase deficiency, for whom elevated pregnanetriol (P3) levels in urine were not suppressed during treatment with cortisone acetate (65 mg/m2 x day), was examined. The activation of cortisone to cortisol was assessed by measuring urinary metabolites of cortisone and cortisol. The patient's inability to respond to treatment with cortisone acetate was found to be caused by a low conversion of cortisone to cortisol, assumed to be secondary to low 11beta-hydroxysteroid dehydrogenase activity (11-oxoreductase deficiency). All exons and exon/intron junctions of the 11beta-hydroxysteroid dehydrogenase type1 gene (HSD11L) were sequenced without finding any mutations, but a genetic lesion in the promoter or other regulatory regions cannot be ruled out. The deficient 11-oxoreductase activity seems to have been congenital, in this case, but can possibly be attributable to a down-regulation of the enzyme activity. The results support the use of hydrocortisone, rather than cortisone acetate, for substitution therapy in adrenal insufficiency.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1999

Growth hormone treatment of patients with Prader-Willi syndrome. Swedish Growth Hormone Advisory Group.

Several studies have now been published on the effect of one or several years of growth hormone treatment on growth and body composition of children with Prader-Willi syndrome. The majority of the patients have responded with greatly increased growth rate, decreased body fat and increased muscle volume. Many of these children seem to have a functional growth hormone deficiency, probably secondary to their hypothalamic dysfunction. Further studies are needed to establish the long-term effect of this treatment on somatic and psychological well-being.

Body Composition↗
PubMed1998

Functional characterisation of mutations in the ligand-binding domain of the androgen receptor gene in patients with androgen insensitivity syndrome.

Five mutations in the ligand-binding domain of the androgen receptor gene were identified in patients with complete (A765T, C784Y, R831X and M895T) or partial (R840G) androgen insensitivity. A765T and R831X have been reported previously whereas the other three mutations are novel. Receptors carrying these mutations were transiently expressed in COS-1 cells, and androgen binding and capacity to transactivate an androgen-responsive reporter gene were assayed. C784Y led to abolished androgen binding and transactivating capacity, R840G and M895T showed reduced specific binding and partial transactivation. The in vitro functions of the R840G and M895T mutants were improved with supraphysiological concentrations of steroid.

Androgen-Insensitivity Syndrome↗
PubMed1998

Growth hormone treatment of children with Prader-Willi syndrome affects linear growth and body composition favourably.

We have compared the growth and the body composition in children with Prader-Willi syndrome (PWS) with and without growth hormone treatment (recombinant GH 0.1 IU/kg/day) after a 1-y period. Twenty-nine prepubertal children with PWS, with mean body mass index (BMI) SDS of 2.2, and 10 (control) healthy obese children with mean BMI SDS of 5.6, underwent 24-h frequent blood sampling. Both PWS and control obese children had low and similar GH levels (0.7 microg/l +/- 0.4SD). Serum IGF-I levels, however, were significantly lower in children with PWS (-1.5SDS +/- 0.8SD vs -0.2SDS +/- 0.8SD). The 29 PWS children were randomized into 2 groups of 15 and 14 subjects for GH treatment and no treatment, respectively. Height velocity increased from -1.9SDS to + 6.0SDS in the treated group (p < 0.001) and decreased from -0.1SDS to -1.4SDS in the control PWS group during the study year. BMI decreased significantly for the treated group (+3.0SDS to +2.0SDS). Relative fat mass decreased significantly, while fat-free mass increased (p < 0.001) for the treated group. No significant changes were noticed in body composition in the control PWS group. In conclusion, the low spontaneous 24-h GH secretion, regardless of body weight, and the exceptional response to growth hormone treatment together with the finding of low IGF-I levels suggest that growth hormone deficiency is a common feature of PWS, as a result of hypothalamic dysfunction. Treatment with growth hormone is beneficial for the majority of PWS children.

Body Composition↗