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Biomedical subjects

S Halvorsen

Publications and source records attributed to S Halvorsen.

At least 73 records · Page 4Linked to original sources
PubMed1989

Child neuromuscular disease in southern Norway. The prevalence and incidence of Duchenne muscular dystrophy.

In a survey carried out to determine the incidence of Duchenne muscular dystrophy in South East Norway, 38 cases were ascertained among 149,975 live male births during the years 1968-1978. The overall incidence is 1:3,917 in live male births (25.33 x 10(-5). This incidence is compared with those in other studies. There is an apparent drop in incidence in the last cohort studied, and the possible role of genetic counselling and antenatal sexing are discussed.

Adolescent↗
PubMed1989

Immunoreactive erythropoietin and erythropoiesis stimulating factor(s) in plasma from hypertransfused neonatal and adult mice. Studies with a radioimmunoassay and a cell culture assay for erythropoietin.

The objective was to study whether the high erythropoietic stimulatory activity found in plasma from neonatal mice during the growth period is erythropoietin (Ep) alone, or Ep in combination with other factors. Plasma from hypertransfused neonatal (20 d) and adult (13-20 weeks) mice were compared with a radioimmunoassay (RIA) and a cell culture assay for Ep. The RIA determines immunoreactive Ep (iEp) while the cell culture assay reflects erythropoiesis stimulating factor(s) (ESF). Compared to control values, hypertransfusion resulting in PCVs of 55% and higher reduced the mean iEp levels in neonatal and adult mice by 82% and 38%, respectively (P less than 0.01). There was no detectable difference between the mean iEp levels of hypertransfused neonatal and adult animals (P greater than 0.3). The parallel ESF data showed a reduction in mean plasma ESF levels by 68% in hypertransfused neonatal and 72% in hypertransfused adult animals (P less than 0.001). And notably, in contrast to the iEp data, the mean ESF level found in hypertransfused neonatal mice with PCVs of 55% and higher was significantly above that of hypertransfused adult animals (P less than 0.001). No correlation was found between PCV and iEp (r less than 0.4, P greater than 0.1) or ESF (r less than 0.2, P greater than 0.2) in hypertransfused animals. The parallel data from the two Ep assays show that plasma from hypertransfused 20-d-old mice contain one or more erythropoietic stimulatory factors not detected by the RIA. It is concluded that part of the high erythropoietic stimulatory activity found in plasma from neonatal mice is due to non-Ep factors.

Age Factors↗
PubMed1989

Correlation of plasma erythropoiesis stimulating factor(s) and immunoreactive erythropoietin levels during rapid growth in the mouse.

During the early neonatal period of rapid growth in the mouse, increased plasma levels of erythropoiesis stimulating factor(s) (ESF) have been found when measured by an in-vitro bioassay technique. It is unclear whether these increased ESF levels represent increased levels of circulating erythropoietin (Ep) alone or Ep in combination with other less-defined erythropoietic stimulatory factors. To examine this issue, plasma from neonatal mice of varying post-natal ages and from normoxic and hypoxic adult mice was studied. We found that plasma Ep levels measured by radioimmunoassay (RIA) correlated significantly with in-vitro bioassayed ESF levels (r = 0.84, P less than 0.0001, n = 21). Although an in-vivo bioassay for plasma Ep proved too insensitive for rigorous correlation with data from the RIA and in-vitro bioassay, the in-vivo data were in qualitative agreement with the other two, more sensitive, assays. In all three assays the highest plasma levels were observed in the 20-day-old mice and in adult mice which had been subjected to hypobaric hypoxia for 8 h. Based on the strong agreement of the results obtained with the RIA and the in-vitro bioassay in both neonatal and adult mouse plasma, we conclude that the high plasma ESF levels of 20-day-old mice measured with the in-vitro bioassay are largely immunochemically identifiable Ep. However, the data also suggest the presence of non-Ep factors in neonatal plasma which stimulate the in-vitro bioassay.

Age Factors↗
PubMed1988

A comparison between haematological parameters in 'capillary' and venous blood from healthy adults.

In 40 healthy adult volunteers of both sexes blood samples were taken simultaneously from an antecubital vein in EDTA-Vacutainers and from a fingertip in EDTA-Microtainers. Haematological measurements were subsequently performed in an Ortho-ELT 800 WS analyzer. Significant differences were obtained between the two sets of samples. In accordance with current literature, the 'capillary' thrombocyte count was either identical to, or more frequently substantially lower than the corresponding venous count. On the contrary, the 'capillary' erythrocyte count and the haematocrit and haemoglobin values significantly exceeded those of venous blood, while the red cell indices MCV, MCH and MCHC were identical. The total leucocyte count was substantially elevated in 'capillary' blood compared with the corresponding venous samples. Moreover, the 'capillary' differential leucocyte counts showed elevations which directly reflected the various particles' size. Possible explanations of these findings are discussed.

Adult↗
PubMed1988

Child neuromuscular disease in southern Norway. Prevalence, age and distribution of diagnosis with special reference to "non-Duchenne muscular dystrophy".

The prevalence of child neuromuscular disease in Southern Norway by January 1st, 1983, was studied by collecting data from all available sources. All children born 1. 1. 1965 or later were included in the study. The total group consisted of 110 patients from 17 different diagnostic categories. Total prevalence on this group was found to be 24.9 X 10(5). Duchenne muscular dystrophy (DMD), with a prevalence of 10.89 X 10(5) constituted 29.2% of the total material. In the spinal muscle atrophy group (SMA), we found a significant increase in the number of boys affected, although an autosomal recessive mode of inheritance was found likely in all probands. Prevalence figures of child neuromuscular disease are hard to compare, as most studies deal with an adult population. The prevalences of common and well-known large categories of neuromuscular diseases in childhood are in agreement with previous studies. For less well known and mild diseases, our figures are low. This may be due in part to a later onset and in part to a health system not sensitive to parents' complaints.

Adolescent↗
PubMed1988

Fasting plasma amino acid concentrations in PKU children on two different levels of protein intake.

Two groups of children with phenylketonuria were treated with different amounts of protein. One group (RDA group) received protein as recommended by the U.S. Food and Nutrition Board, the other (FAO group) the amount recommended by the FAO/WHO 1973 ad hoc Expert Committee. Two of the children in the FAO group showed a decrease in length/growth velocity which raised the question of the adequacy of the protein content in the diet. Since deviations from normal plasma amino acids have been observed in protein deficient, energy-adequate diets, we examined these parameters in the PKU children. In the two children with retardation in length/growth, very high glycine values as well as very high alanine values were observed at the end of the study. These observations strengthened our suspicion that the FAO/WHO 1973 recommendations are marginal.

Amino Acids↗
PubMed1987

Is oxygen supply the only regulator of erythropoietin levels? Serum immunoreactive erythropoietin during the first 4 months of life in term infants with different levels of arterial oxygenation.

Serum immunoreactive erythropoietin (siEp) levels were measured in 35 full-term infants aged 0-13 weeks, 31 of whom had congenital heart disease. The infants displayed a wide range in arterial oxygen tension (PaO2) and oxygen saturation (SaO2). During the first days of life siEp varied widely with a range from less than 3 to more than 10,000 mIU/ml. The wide variation is consistent with findings in cord blood at term. The siEp levels did not correlate significantly with haemoglobin, haematocrit, PaO2, SaO2, or arterial oxygen content in the total sample, nor when the cohort was split up into different age groups. Cyanotic infants aged 2-13 weeks had significantly higher siEp concentrations than normal adults (p less than 0.001) and than children with cyanotic congenital heart disease, aged 4 months-10 years (p less than 0.001). The raised siEp levels in cyanotic children aged 2-13 weeks found in this study and the normal levels found in their older counterparts (4 months-10 years) (reported elsewhere) are consistent with the pattern observed in man and animals exposed to prolonged hypobaric hypoxia, in which after an initial rise in erythropoietin concentrations the levels fall to normal while increased erythropoiesis is sustained.

Cross-Sectional Studies↗
PubMed1987

Erythropoietic factors in plasma from neonatal mice. In vivo studies by the exhypoxic polycythaemic mice assay for erythropoietin.

The erythropoiesis stimulating factor(s) (ESF) in plasma from 20-day-old WLO-mice have previously been studied by a cell culture assay, and also by means of gel filtration chromatography and affinity chromatography. It was concluded that the high levels of ESF found in the neonatal mouse plasma probably consisted of erythropoietin (Ep) alone. The objective of the present investigation was to obtain further information of whether this high ESF found in vitro is Ep alone, or Ep in combination with other factors. To accomplish this plasma from 20-day-old WLO mice and a standard Ep were studied in vivo by the exhypoxic polycythaemic mice assay for Ep, with and without preincubation with rabbit anti-Ep serum (AS). Aliquots of some samples were also studied in vitro by the exhypoxic polycythaemic mice assay for Ep, with and without pre- in both assays (P less than 0.001). However, incubation with AS significantly reduced (P less than 0.001) but did not totally block either the in vivo or the in vitro activity of the plasma (P less than 0.005). This also was the case regarding the in vivo activity of the standard Ep (P less than 0.001), while the in vitro activity of this Ep preparation was totally blocked by incubation with AS (P greater than 0.3). These results indicate that a considerable part of the high erythropoietic stimulatory activity found in plasma from 20-day-old mice, with both assays, is Ep. This supports the previous in vitro studies. However, the present results also support the conclusion that part of the activity is due to non-Ep stimulatory factors.

Age Factors↗
PubMed1987

Regulation of erythropoiesis in suckling rabbits with and without postnatal anemia: partial suppression of production/release of erythropoiesis stimulating factor(s) by iron supplements.

The postnatal anemia in rabbits is accompanied by a marked rise in the plasma erythropoiesis stimulating factor(s) (ESF). The purpose of this study was to establish whether the increase in plasma ESF is only related to the anemia, or whether other mechanisms also are involved. Two matched groups of rabbits were studied from the 15th to the 36th day after birth. One group received iron parenterally and had no postnatal fall in hemoglobin concentration (Hb), the other developed the usual anemia. In both groups plasma ESF was undetectable on the 15th day, and also on the 22nd day, despite a marked fall in Hb in the untreated group and rise in the iron-treated group. Thereafter plasma ESF showed a slight, continuous rise in the nonanemic rabbits, in contrast to a marked, transient rise with maximum on the 29th day in the untreated group. On the 36th day there was no difference between the groups. In the iron-treated group the reticulocyte production rate remained unchanged, while the Hb mass rose continuously. In the untreated animals there was an initial decline in reticulocyte production rate, while Hb mass showed a slight increase. From the 29th day, however, reticulocyte production rate rose to the same level as in the iron-treated group and Hb mass rose markedly. In conclusion, the rise in plasma ESF during the postnatal anemia in rabbits is only in part related to the low Hb. Hypoxia-independent mechanisms, probably related to the growth and maturation per se also are involved. The lack of erythropoietic response to the rise in plasma ESF is due to lack of available iron.

Anemia↗
PubMed1987

Plasma erythropoiesis stimulating factor(s) in neonatal mice: in vitro dose response and chromatography studies.

High levels of plasma erythropoiesis stimulating factor(s) (ESF) have been found in neonatal WLO-mice during rapid growth. A previous study on hypertransfused neonatal animals indicated that the high ESF could not be due to the concomitant postnatal anemia alone. The present investigation was performed to answer the question: Is the high plasma ESF in neonatal WLO-mice erythropoietin (Ep) alone, or Ep in combination with other factors? The ESF of plasma from 20-day-old animals and standard Ep were compared in a cell culture assay for ESF based on erythroid colony formation, and also by means of gel filtration chromatography and affinity chromatography. Nonfractionated plasma and standard Ep showed parallel dose response curves and additive activity in the ESF assay. After gel filtration the detectable ESF of plasma was eluted in the same position as that of standard Ep, corresponding to an estimated molecular weight range of 34-65,000 daltons. The ESF of intact plasma, fractionated plasma, and standard Ep were identically bound to and eluted from the affinity chromatography column. These results show that the ESF of plasma from 20-day-old animals can neither be separated into several factors, nor distinguished from that of standard Ep by the methods used. It is therefore concluded that the high plasma ESF found in neonatal WLO-mice probably consists of Ep alone.

Animals↗
PubMed1986

Liver transplantation in a 23-year-old tyrosinaemia patient: effects on the renal tubular dysfunction.

Orthotopic liver transplantation was performed on a 23-year-old female with hereditary tyrosinaemia. The disorder was diagnosed at 7 years of age due to severe rickets, and the patient was treated with a diet restricted in phenylalanine and tyrosine. Nineteen months before the transplantation she had an acute episode of diffuse gastrointestinal bleeding due to portal hypertension. Three subsequent bleeding episodes with accompanying ascites and signs of encephalopathy were considered life-threatening. Nine months after the liver transplantation the patient is well, but serum transaminases are slightly elevated. Without dietary restrictions serum tyrosine and inorganic phosphate are normalized, no succinylacetone can be detected in serum, and urinary excretion of p-hydroxyphenyllactate and p-hydroxyphenylpyruvate is normal. Excretion of amino acids, glucose and beta 2-microglobulin decreased significantly after the transplantation but is still elevated. The succinylacetone concentration in urine is about 20% of the preoperative level. After an oral tyrosine load, succinylacetone excretion increased sevenfold but no deterioration of the renal tubular function was observed and no tyrosine metabolites were detectable in serum. The findings indicate that the defective tyrosine metabolism occurs in the kidneys, but does not produce tubular dysfunction. The residual tubular dysfunction of the patient is probably due to irreversible damage of the tubular epithelium.

Adult↗
PubMed1986

Erythropoiesis-stimulating factor(s), erythropoiesis and erythrocyte 2,3-diphosphoglycerate in young rabbits with marked post-natal fall in haemoglobin.

The erythropoietic activity and erythrocyte 2,3-diphosphoglycerate (2,3-DPG) were studied during and after the nadir of the post-natal anaemia in normal, rapidly growing rabbits, from the 12th to the 35th day after birth. Whole blood haemoglobin (Hb) decreased from 9.3 g dl-1 on the 12th to 4.9 g dl-1 on the 25th day, while erythropoiesis-stimulating factor(s) (ESF) in plasma (determined by a cell culture assay) concomitantly rose from undetectable to high levels. In spite of marked rise in body weight, from 250 to 480 g, estimated haemoglobin mass (Hb mass) and reticulocyte mass production rate (Rt prod) remained essentially the same, about 1.8 g and 0.3 ml day-1. From the 25th to the 35th day, ESF decreased to a lower level, while Hb increased to 10.8 g dl-1 and Hb mass and Rt prod rose sharply, to 6.9 and 1.2 ml day-1. The 2,3-DPG rose markedly during the observation period, but showed a transient decline on the 29th day, simultaneously with the peak in reticulocyte counts (Rt) (24%) and release of young erythrocytes with low 2,3-DPG. The data indicate that the regions governing the erythropoietin production/release became increasingly sensitive to hypoxia during the observation period. The possibility also exists that the increase in ESF was due only in part to hypoxic stimulation. It could be related to the maturation of the animal in other ways, such as shift from extra-renal to renal erythropoietin production and the growth. The lack of response to increasing stimulation indicates that the erythropoiesis was restricted by the availability of iron and/or other factors necessary for erythrocyte and haemoglobin production.

2,3-Diphosphoglycerate↗