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Biomedical subjects

J Knudtzon

Publications and source records attributed to J Knudtzon.

At least 19 recordsLinked to original sources
PubMed1998

Homozygous mutation (A228T) in the 5alpha-reductase type 2 gene in a boy with 5alpha-reductase deficiency: genotype-phenotype correlations.

The molecular basis of a patient with 5alpha-reductase deficiency was investigated in this study. This disease is a rare form of male pseudohermaphroditism with virilization during puberty. The child was raised as a girl, but had a male gender identity early in life. The diagnosis was set at the age of 13 years when the virilization process began. Hypospadias repair was performed and he changed to a male gender. DNA sequence analysis disclosed a homozygous mutation in exon 4 of the 5alpha-reductase type 2 gene, alanine 228 for threonine. The heterozygous parents are first cousins of Pakistani origin.

Adolescent↗
PubMed1996

Efficacy and safety of cholestyramine therapy in peripubertal and prepubertal children with familial hypercholesterolemia.

OBJECTIVE: To determine the efficacy and safety of cholestyramine therapy in young children with familial hypercholesterolemia. SUBJECTS: Boys aged 6 to 11 years (n = 57) and girls aged 6 to 10 years (n = 39) with familial hypercholesterolemia. DESIGN: After 1 year of a low-fat, low-cholesterol diet, children with low-density lipoprotein (LDL) cholesterol levels > or = 4.9 mmol/L (190 mg/di) or < or = 4.1 mmol/L (160 mg/dl) in the presence of familial premature cardiovascular disease were randomly assigned to a double-blind comparison of 8 gm cholestyramine (n = 36) and placebo (n = 36) for 1 year. OUTCOME MEASURES: The primary efficacy and safety outcomes were serum LDL cholesterol levels and height velocity, respectively. Secondary safety outcomes were erythrocyte folate, total plasma homocysteine, serum fat-soluble vitamins, and side effects. RESULTS: Twenty-two subjects in the cholestyramine group and 26 in the placebo group completed the 1-year study. Most withdrawals from the study were related to unpalatability of the study drug or placebo. The LDL cholesterol levels changed by -16.9% (95% confidence interval, -10.8% to -22.9%) in the cholestyramine group compared with 1.4% (95% confidence interval, -4.4% to 7.2%) in the placebo group. Mean height velocity standard deviation scores during 1 year for the children in the cholestyramine and the placebo groups who had not started puberty were 0.24 +/- 1.14 and 0.11 +/- 0.68, respectively (not significant). In the cholestyramine group, mean levels of 25-hydroxyvitamin D decreased. One girl had low folate and elevated homocysteine levels, and there was one case of intestinal obstruction caused by adhesions. CONCLUSIONS: Significant reductions in LDL cholesterol are achievable during treatment with cholestyramine in about half of eligible children. Growth is not adversely affected. Folate deficiency may occur, even with a low dose of cholestyramine, and vitamin D supplements should be considered. Caution should possibly be exercised in starting cholestyramine therapy within 3 months of abdominal surgery in children.

Anticholesteremic Agents↗
PubMed1996

X chromosome inactivation pattern in female carriers of X linked hypophosphataemic rickets.

X linked hypophosphataemia (XLH) results from an abnormality of renal tubular phosphate reabsorption. The disorder is inherited as an X linked dominant trait and the gene has been mapped to Xp22.1-p22.2. A candidate gene (PEX) has recently been isolated. The most striking clinical features are growth retardation and skeletal abnormalities. As expected for X linked dominant disorders, females are less affected. However, such a gene dosage effect does not exist for renal phosphate reabsorption. Preferential X chromosome inactivation has been proposed as a possible explanation for this lack of gene dosage. We have examined the X inactivation pattern in peripheral blood cells from 12 females belonging to seven families with XLH using PCR analysis at the androgen receptor locus. The X inactivation pattern in these patients did not differ significantly from the pattern in 30 healthy females. The X inactivation pattern in peripheral blood cells does not necessarily reflect the X inactivation pattern in renal cells. However, the finding of a normal distribution of X inactivation in peripheral blood cells indicates that the similarity in the renal handling of phosphate in male and female patients is not related to a ubiquitous preferential X inactivation.

Adult↗
PubMed1995

Autonomous hyperparathyroidism in X-linked hypophosphataemia.

Four patients with familial hypophosphataemic rickets developed significant hypercalcaemia which persisted after discontinuation of vitamin D therapy. They had increased PTH levels and were operated for hyperparathyroidism at the ages of 18, 20, 24 and 45 years, respectively. Three of the patients had previously received phosphate treatment and one patient developed hyperparathyroidism 7 years after treatment with calcitriol. Histological evaluation revealed different degrees of parathyroid hyperplasia in all patients, with persistently increased PTH and/or calcium levels after surgery. The possibility of autonomous hyperparathyroidism should be evaluated in the follow-up of patients with X-linked hypophosphataemic rickets.

Adult↗
PubMed1993

[Bone mineral density and occurrence of fractures in 66-year old women in Oslo].

During 1991 we examined 196 randomly chosen females born in 1925 and resident in Oslo. 40% had suffered fractures of the appendicular skeleton, most commonly of the forearm and the ankles, after the menopause. Results from bone mineral density measurements of the lumbar spine (L2-4) and the femoral neck were not significantly lower, while results from the distal 1/3 of the forearm site were significantly lower, among participants with fractures than among participants without fractures. The values for bone mineral density obtained from these three sites corresponded with the values reported from other countries. Biochemical indices of calcium metabolism were similar in fracture and non-fracture subjects. Age at menopause, weight, height and demographic characteristics were also similar in the two groups. We conclude that low bone mineral density cannot be the sole explanation of the very high prevalence of fractures among female residents of Oslo found in the present and previous studies.

Adult↗
PubMed1993

[Endocrine disorders in adolescents and young adults].

Evaluation of 158 patients younger than 25 years-of-age who had been hospitalized in a specialized adult endocrine department during an 11 year-period, brought to light specific endocrine problems connected both to pediatrics and internal medicine. There is need for close collaboration between pediatricians, as experts on disturbances in growth and pubertal development, and internists, with experience of diagnosing rare endocrinological disorders. Such collaboration might also improve the follow-up of young patients into adulthood.

Adolescent↗
PubMed1993

Kallmann syndrome in two sisters with other developmental anomalies also affecting their father.

The classical features of Kallmann syndrome with anosmia and hypogonadotropic hypogonadism were observed in two sisters aged 13 and 19. They had additional malformations including anosmia, bilateral vesico-ureteral reflux and unilateral hearing loss. One of the girls had unilateral coloboma of the optic nerve. The father had unilateral hearing loss and duplication of the left ureter; he died of an unrecognized coarctation of the aorta. He had no clinical signs of hypogonadism or anosmia. It is suggested that the malformations observed in these patients may be due to a dominant inherited defect of embryonic cell migration, resulting in different phenotypic expressions within the same family, including the Kallmann syndrome.

Adolescent↗
PubMed1993

Results of two years of growth hormone treatment followed by combined growth hormone and oestradiol in Turner syndrome. The Norwegian Turner Study Group.

The effects of treatment with human growth hormone (GH) for 2 years, followed by combined treatment with GH and oestradiol valerate, were studied in girls with Turner syndrome, aged 7.0-16.6 years. Height SDS (Turner standards) increased after GH treatment, and height velocity SDS (Turner standards) increased dramatically 6 months after the start of GH treatment and gradually declined after 2 years' treatment. A further increase occurred after 18 months of GH and oestradiol treatment in conjunction with the pubertal growth spurt, followed by a decline 6 months later. Height SDS for bone age increased during GH treatment, and remained virtually unchanged after the introduction of oestradiol. Predicted final height increased after the first year of GH treatment only. The use of GH and oestrogen treatment in Turner syndrome is discussed in the light of these preliminary results.

Adolescent↗
PubMed1992

[Mental retardation in children. Prevalence and etiology].

The prevalence of mental retardation defined as IQ less than 70 has been estimated as ranging between 6.7-11.9 per thousand children in the Nordic countries. Etiological factors can be found in 80% of patients with severe mental retardation (IQ less than 50) and in 50% with mild mental retardation (IQ 50-70). Down's syndrome is the most common specific cause of mental retardation, followed by the Fragile X syndrome, which mainly affects boys. Since the middle of the 1980s Rett's syndrome has been recognized as the most frequent cause of progressive mental retardation in girls. Recent advances in the field of chromosomal disorders, metabolic diseases and clinical syndromes imply a need for new epidemiological research aimed at obtaining an updated picture of the heterogenous causes of mental retardation.

Adolescent↗
PubMed1991

[The "Large Foot" association. The size of the foot, height and age at menarche].

A slight negative correlation (r = -0.198) was found between age at menarche and size of shoe in 106 women from a Norwegian organization for persons using shoe sizes larger than 41. The correlation between stature and size of shoe was smaller (r = 0.086). These findings are discussed with respect to normal growth of the foot and body stature. Since pubertal growth of the foot occurs before the pubertal growth spurt, it is unlikely that oestrogen treatment for tall stature will affect foot length to any degree. The authors also discuss psychological and physical problems related to large feet.

Adolescent↗
PubMed1991

[Ectopic liver in the gallbladder and cholestasis].

A small ectopic liver on serosa of the gallbladder was demonstrated peroperatively in two patients with extrahepatic cholestasis and considerable distention of the biliary system. The histological architecture of the small liver was similar to that of a normal liver, with a minute bile duct communicating with the lumen of the gallbladder. This explains why the cholestasis provoked identical pathological changes in both liver and the ectopic liver tissue.

Adult↗
PubMed1991

Routine measurements of gluten antibodies in children of short stature.

Serum IgA and IgG gluten antibody levels were measured prospectively in 168 children without abdominal symptoms referred to the outpatient clinic for short stature. Elevated (greater than 0.30 units) gluten IgA antibody levels (0.82 +/- 0.22 units) were detected in five children (aged 8.5 +/- 1.6 years, height standard deviation score -2.14 +/- 0.26). They had probable celiac disease based on villus atrophy at duodenal biopsy, in vitro toxicity of wheat gluten, and disappearance of serum gluten antibodies after gluten withdrawal from the diet. Three of these children had elevated IgG antibody levels (greater than 0.25 units). Elevated IgG antibody levels with normal IgA levels were demonstrated in 11 short children who had normal duodenal biopsy results. It is concluded that measurement of gluten antibodies, especially of the IgA type, should be included in the diagnostic evaluation of children with short stature.

Adolescent↗
PubMed1991

Baroreflex responsiveness during hypobaric hypoxia.

Baroreflex responses to graded neck suction during held expiration were studied in five healthy females at sea level and at a simulated altitude of 4,572 m (15,000 ft), with and without oxygen administration. An apparent resetting of the baroreflex was observed during hypobaric hypoxia, but this effect was abolished by oxygen administration. Held expiration alone induced a pulse prolongation in all experimental conditions, however this bradycardiac response was smaller during hypobaric hypoxia than during the two normoxic conditions. When the bradycardic responses of held expiration were subtracted, the baroreflex responses to neck suction were equal in all experimental situations. Similarly, the baroreflex was unaffected by hypobaric hypoxia when the R-R interval prolongations were expressed in percentage of the R-R intervals immediately prior to the neck suction. These data indicate that reduced ambient pressure per se has no influence on the carotid baroreflex control of heart rate.

Adult↗
PubMed1990

[Survey of growth hormone deficiency in children].

When other causes of retarded growth have been ruled out, investigation for classic growth hormone deficiency is indicated in children with reduced velocity of growth and retarded bone development. In cases of classic growth hormone deficiency there is insufficient increase in growth hormone levels after two stimulation tests. However, some short children whose stimulation tests are normal but whose spontaneous growth hormone secretion is reduced or pathological may possibly benefit from growth hormone treatment. Therefore measurements of spontaneous growth hormone secretion and insulin-like growth factor IGF-1 have also been used in the diagnosis of growth hormone-related short stature. The authors present a overview of the diagnosis of growth hormone deficiency in practice based on their own experience.

Growth Disorders↗
PubMed1990

[Survey of growth retardation in children].

Following investigation of 172 children submitted for retarded growth, 34 children obtained a specific diagnosis. 11 of these children had growth hormone deficiency and five had coeliac disease. The remaining 138 children either had genetically determined short stature or their growth and adolescence was constitutionally delayed. 27 prepubertal children received treatment with anabolic steroids, and 17 children were treated with growth hormone. We present a practical approach for the investigation of retarded growth.

Adolescent↗