Search PubMed⌕ Search

Biomedical subjects

S Halvorsen

Publications and source records attributed to S Halvorsen.

At least 91 records · Page 5Linked to original sources
PubMed1985

Net protein utilization determined by rat bioassay of a protein hydrolysate and a diet for children with phenylketonuria.

In a previous study (Kindt et al. 1983, 1984) it was assumed that a protein hydrolysate, devoid of phenylalanine, together with intact protein as given to children with phenylketonuria (PKU), was equivalent to egg or milk protein. One group of children was given this 'PKU protein' in amounts corresponding to the Joint FAO/WHO ad hoc Expert Committee (1973) recommendations. The results indicated that the Joint FAO/WHO ad hoc Expert Committee (1973) recommended levels of protein intake were marginal. The purpose of the present study was to evaluate whether the quality of the protein hydrolysate, together with intact protein ('PKU protein'), is equivalent to egg or milk protein. This was done using a rat bioassay. Four protein sources were used: (1) egg protein, (2) protein hydrolysate, (3) protein hydrolysate diluted with non-essential amino acids, (4) protein hydrolysate mixed with food proteins ('PKU protein'), comparable with the diet previously used (Kindt et al. 1983, 1984). The results indicated that the 'PKU protein' was of very high quality: net protein utilization (NPU) greater than 90. The protein hydrolysate alone and the protein hydrolysate diluted with non-essential amino acids gave a NPU greater than 80. The conclusion drawn from the present study is that the 'PKU protein', as used in the treatment of children with PKU, is equivalent to egg or milk protein. This supported the view that the Joint FAO/WHO ad hoc Expert Committee (1973) recommended levels of intake were marginal.

Animals↗
PubMed1985

Regulation of erythropoiesis during rapid growth.

High levels of plasma erythropoiesis stimulating factor(s) (ESF) have been found in neonatal WLO-mice during the period of rapid growth. If the high ESF activity is due to the concomitant physiological anaemia of infancy alone, it should be possible to block erythropoiesis by hypertransfusion. Mice were hypertransfused starting on day 14, and killed on day 20. Although hypertransfusion reduced the ESF levels by approximately 55% (P less than 0.001), ESF levels were still detectable in the cell culture assay used (P less than 0.001). Moreover, hypertransfused mice showed active erythropoiesis in the bone marrow, and none had a reticulocyte count below 2%. No correlation was found between PCV and ESF in the hypertransfused animals (r = 0.07, P greater than 0.5), nor was there any difference in weight gain between control and hypertransfused mice (P greater than 0.5). These results show that hypertransfusion did not totally supress erythropoiesis in neonatal WLO-mice, which is different from hypertransfused adult mice. The data indicate that the high plasma ESF found in neonatal WLO-mice during the growth period are not due to the anaemia alone. These findings support studies indicating that regulation of erythropoiesis in the neonate differs from the adult. Factors related to growth per se could be responsible for this difference.

Animals↗
PubMed1984

Is phenylalanine requirement in infants and children related to protein intake?

Two groups of children with phenylketonuria (PKU) received protein at two different levels. The protein source was a protein hydrolysate, devoid of phenylalanine, and intact protein from milk, vegetables and fruit. One group (RDA group) was given protein at a level based on the recommendations of the (US) Food and Nutrition Board (1974, 1980). The other group (FAO group) was given protein at the level of intake corresponding to the Joint FAO/WHO ad hoc Expert Committee (1973) safe levels of intake of egg or milk protein. The children were monitored very closely for several years. From an earlier study evaluating the protein intake of the two groups it was suspected that the Joint FAO/WHO ad hoc Expert Committee (1973) recommendations were marginal. In the present study the phenylalanine intake of the two groups required to maintain the plasma phenylalanine concentration at the required level was established. The results showed that the RDA group required more phenylalanine than the FAO group. This difference was statistically significant from the age of 5-15 months. We have interpreted the greater requirement for phenylalanine in the RDA group as a result of a greater nitrogen intake and thus a more rapid chemical maturation of N (increase in protein concentration of the body with age). It is known that up to the age of 6 months the chemical maturation of N is related to the N intake. In the present study we have found that this difference in chemical maturation lasted up to the age of 15 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Weight↗
PubMed1984

Plasma concentrations of vitamin D metabolites before and during treatment of vitamin D deficiency rickets in children.

Plasma concentrations of 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D (1,25-(OH)2D), and 24,25-dihydroxyvitamin D (24,25-(OH)2D) were determined in 17 children with vitamin D deficiency rickets before therapy was started. Thirteen of them also had these tests repeated during treatment. The median 25-OHD concentration was at the lower limit of the reference range before, but increased distinctly within one week of treatment with 1 700-4 000 IU vitamin D per day (17 vs. 37 nmol/l, p less than 0.01). 24,25-(OH)2D was undetectable in twelve of the patients before therapy. Detectable concentrations were in the range of 1.7 to 3.5% of the corresponding 25-OHD levels throughout the study, and the two metabolites were closely correlated (r = 0.84, p less than 0.0005). The median 1,25-(OH)2D concentration was near the average of the reference range before, but increased to well above the upper limit of normal within one week of treatment (121 vs. 368 pmol/l, p less than 0.01). The levels were largely normal after 10 weeks of therapy, as were the plasma concentrations of calcium, phosphate, and alkaline phosphatase. Parathyroid activity, as judged by serum parathyroid hormone or urinary cyclic AMP concentrations, was stimulated in 11 of 12 children studied prior to treatment. It is concluded that there may be no clear-cut differences between normal nad rachitic values of the different vitamin D metabolites under practical clinical conditions. A low 25-OHD level combined with evidence of a stimulated parathyroid activity, and a rise of 1,25-(OH)2D levels to supernormal values following a few days of vitamin D therapy may be diagnostic clues.

24,25-Dihydroxyvitamin D 3↗
PubMed1984

Erythrocyte 2,3-diphosphoglycerate, PO250%, and available oxygen in young rabbits with and without postnatal fall in hemoglobin.

We determined erythrocyte 2,3-diphosphoglycerate (2,3-DPG), PO250%, whole blood hemoglobin concentration, and available O2 from the 12th to the 30th d after birth in two matched groups of young rabbits. One group received iron parenterally on the 12th, 15th, and 18th d and the other received no iron supplement. In the untreated group there was a marked fall in hemoglobin concentration from the 12th to the 22nd d and thereafter a marked increase to the initial level on the 30th d whereas the iron-treated animals showed a marked rise in hemoglobin concentration from the 12th to the 22nd d, and a subsequent, slight decline from the 22nd to the 30th d. The average values of PO250% and 2,3-DPG, and the changes in PO250% and 2,3-DPG were virtually identical for both groups. During the first period (12-22 d) there was a marked rise in both 2,3-DPG and PO250% whereas in the second period (22-30 d) there was a somewhat smaller rise in 2,3-DPG and only a slight tendency toward a further rise in PO250%. In the untreated animals "available O2," reflecting the O2 delivery capacity of the blood, remained unchanged during the period of fall in hemoglobin concentration and showed a rise during the second period. In the iron-treated animals "available O2" rose markedly during the first period, with iron-treatment, and remained unchanged during the second period. We conclude that the marked postnatal rise in 2,3-DPG and PO250% in the rabbit seems to be independent of the changes in the hemoglobin concentration.

2,3-Diphosphoglycerate↗
PubMed1984

Regulation of erythropoiesis.

The regulation of erythropoiesis is an important factor in maintaining normal blood viscosity. In this short summary the three erythroid compartments in the bone marrow are described: the stem cells, the committed cells and the morphologically recognisable cells. The stimulating factors burst forming activity (BFA) and erythropoietin (Ep) act on the committed cells. The production of Ep is regulated through tissue oxygenation while BFA seems to be unrelated to this. Under normal conditions erythropoiesis is a well regulated system, while under pathological conditions it may escape control and thus give rise to very high haematocrits and increased blood viscosity.

Blood Viscosity↗
PubMed1983

Protein requirements in infants and children: a longitudinal study of children treated for phenylketonuria.

Two groups of children with phenylketonuria were followed from birth for several years. The Recommended Dietary Allowance group received a protein intake as recommended by the Food and Nutrition Board. The Food and Agricultural Organization (FAO) group received a protein intake as recommended by FAO. The children were followed very closely for the biochemical control of the disease. The children were also followed very closely to evaluate the adequacy of the protein intake using length, weight, routine hematology, chemical analysis, and x-ray of the hand. The results indicated two groups of healthy children. However, a decline in length growth percentile was found in some of the FAO children. A possible osteoporosis developed in two of the FAO children. The possible conclusion that the FAO "safe level of intakes of egg or milk protein" is marginal is discussed.

Age Factors↗
PubMed1983

Plasma erythropoietin concentrations during the early anemia of prematurity.

Plasma erythropoietin concentrations were studied in 11 preterm appropriate for gestational age infants at the age of 3-14 weeks. Their birth weights ranged from 860-1 690 g. Erythropoietin was measured by a cell culture technique. Significant concentrations of erythropoietin was detected in 18 out of 29 samples, at all stages of the early anemia. The highest levels were found at 3-9 weeks. Individual erythropoietin values did not correlate with hemoglobin concentrations, hematocrit levels or 'corrected' reticulocyte counts, nor did the 'corrected' reticulocyte count correlate with hemoglobin or hematocrit. The lack of correlation with hemoglobin concentration most likely reflects the importance of other factors as well as the hemoglobin in determining the oxygenation status of the infant. A significant positive correlation (r = 0.60, p less than 0.01) was found between erythropoietin concentration and weight gain in the preceding week. The study shows that small preterm infants are capable of erythropoietin production during their early anemia, and indicates that the hormone plays a role in the regulation of erythropoiesis also at this time of life.

Anemia, Neonatal↗
PubMed1983

Deficient fumarylacetoacetate fumarylhydrolase activity in lymphocytes and fibroblasts from patients with hereditary tyrosinemia.

Fumarylacetoacetate fumarylhydrolase (E.C.3.7.1.2.), a liver enzyme involved in tyrosine degradation, is shown to be present in many human tissues and cells including lymphocytes, fibroblasts, and cultured amniotic fluid cells. The enzyme activity in lymphocytes from six patients with hereditary tyrosinemia (hepatorenal type) and fibroblasts from three patients, was found to be less than 10% of the activity in control subjects. In lymphocytes and fibroblasts from the parents (n = 16) of the patients the enzyme values were compatible with a heterozygote genotype. The lymphocyte enzyme pattern of the control subjects (n = 97), is complicated, and indicates possible enzyme variants.

Adolescent↗
PubMed1983

Erythropoietin and uremic toxicity during continuous ambulatory peritoneal dialysis.

This study examined the effect of continuous ambulatory peritoneal dialysis (CAPD) on erythropoiesis and macrophage function. The parameters evaluated were hemoglobin, erythropoiesis-stimulating factor(s) (ESF), and the inhibitory effect of patients' plasma and peritoneal dialysate on erythropoiesis in vitro and on the function of macrophages from normal humans cultured in vitro. ESF was determined by a cell culture assay using hepatic erythroid colony forming cells (CFUE) from newborn mice. The uremic inhibitory effect on macrophages cultured in vitro was expressed as macrophage survival in percentage of controls. Five patients were studied, one of whom was anephric. Hemoglobin increased, without blood transfusions during CAPD treatment, suggesting improved erythropoiesis. Plasma ESF increased in all patients; dialysate ESF increased in all but one patient. Survival of macrophage in vitro, incubated with plasma or dialysate, also improved. In two patients, the inhibitory effect of plasma samples on erythropoiesis in vitro decreased during CAPD treatment. These observations indicate that CAPD removes inhibitors of erythropoiesis and human macrophage function in vitro, and are consistent with transport of inhibitory substances of high molecular weight into the peritoneal cavity. The anephric patient showed improvement of erythropoiesis similar to that of the nephric patients, indicating that the kidney may not be the main producer of erythropoietin (Ep) in patients undergoing CAPD. Peritoneal macrophages may be a site of extrarenal Ep production in this situation. With regard to the parameters studied, CAPD treatment is superior to conventional hemodialysis.

Adult↗
PubMed1982

Studies on methanol poisoning.

Eleven patients concomitantly poisoned with methanol are described. Their whole blood methanol concentration ranged from 137.2 mmol/l (4.39 g/l) to 7.4 mmol/l (0.24 g/l). The clinical course in most patients was mild, which was attributed to the concomitant and subsequent ethanol ingestion and rapid transport to dialysing units. One patient suffered permanent visual impairment of one eye while the others recovered completely. Symptoms of poisoning were most clearly correlated to the degree of metabolic acidosis. All patients were hemodialysed. In two patients the average dialysator clearance of methanol was 157 and 176 ml/min at blood flows of 200 and 215 ml/min, respectively. In the same patients the average dialysator clearance of ethanol was 149 and 164 ml/min. Assuming a volume of distribution of methanol of 0.7 l/kg, the dialysator represented about 89 and 95%, respectively, of the total body clearance of methanol during ethanol therapy. Ethanol in concentrations even lower than usually recommended may be useful as the only treatment of patients with blood methanol concentrations up to 15 mmol/l (0.5 g/l), provided there is no acidosis or visual impairment.

Adolescent↗
PubMed1982

Erythrocyte 2,3-DPG, PO2 50% and available O2 during the early post-natal fall in hemoglobin in rabbits.

Erythrocyte 2,3-DPG, PO2 50%, whole blood hemoglobin and available O2, and fixed acid Bohr effect were studied during the first 10 days after birth in rapidly growing suckling rabbits. The post-natal fall in hemoglobin concentration was accompanied by a marked rise in erythrocyte 2,3-DPG and a gradual increase in PO2 50%. The rise in PO2 50% was sufficient to keep the available O2 of the blood unchanged throughout the observation period. The observations show that a 2,3-DPG mediated rise in PO2 50% very effectively contributes to maintenance of adequate tissue oxygenation during the post-natal fall in hemoglobin. The rise in 2,3-DPG and and PO2 50% may be due to the ordinary hypoxia-induced shift to the right of the hemoglobin O2 dissociation curve, as observed under other circumstances when blood hemoglobin is rapidly reduced, but the very marked rise in 2,3-DPG and the very low delta PO2 50%/delta 2,3-DPG ratio suggest that the rise may as well be due to hypoxia independent, pre-programmed processes. The fixed acid Bohr effect was essentially the same in newborn and adult rabbits, and was uninfluenced by large variations in 2,3-DPG.

2,3-Diphosphoglycerate↗
PubMed1981

Influence of HLA matching in cadaveric renal transplantation: experience from one Scandiatransplant center.

The outcome of 461 prospectively HLA-A, -B and -C typed and 193 prospectively HLA-DR typed cadaveric kidney transplants in one center was followed. We found a significant beneficial effect on graft survival both of HLA-A and -B as well as of HLA-DR matching between donor and recipient, while no effects of HLA-C compatibility could be detected. The effect of HLA-DR matching was clearly more pronounced than that of HLA-A and -B matching, and a possible influence of matching for HLA-A and -B could only be seen in the HLA-DR mismatched combinations. Pretransplant blood transfusions were associated with an increased graft survival only in patients receiving HLA-DR mismatched transplants. We conclude that major emphasis should be laid on obtaining HLA-DR compatibility in clinical renal transplantation.

Blood Grouping and Crossmatching↗