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Biomedical subjects

N Clausen

Publications and source records attributed to N Clausen.

At least 55 records · Page 3Linked to original sources

Familial occurrence of neuroblastoma, von Recklinghausen's neurofibromatosis, Hirschsprung's agangliosis and jaw-winking syndrome.

A family is reported with ganglioneuromas in the mother and neuroblastomas in her two daughters co-existing with cases of von Recklinghausen's neurofibromatosis, Hirschsprung's agangliosis, and the jaw-winking syndrome in other family members. There were no detectable constitutional chromosomal defects in the family even when high resolution techniques were applied. Similarly, DNA-hybridization analysis did not reveal gross molecular rearrangements in the vicinity of the proto-oncogenes N-myc-, c-myc, neu, and N-ras. However, the aggregation of several rare, autosomal dominant diseases affecting tissue derived from the neural crest not only suggest a link between te pathogenesis of these disease, but also makes it highly likely that a single mutation segregating within the family is responsible for this association.

Adult↗

Direct long-term effects of L-asparaginase on rat and human pancreatic islets.

L-Asparaginase, an effective agent in the treatment of acute lymphoblastic leukemia, may induce a diabetic state. The pathogenesis of the diabetogenic effect was studied in cultured pancreatic islets. Mean serum concentrations in three children with acute lymphoblastic leukemia were 2.4 U/mL (range 1.4-4.5) before and 31.5 U/mL (range 18.6-51.8) immediately after an intravenous injection of 1000 U/kg L-asparaginase. Glucose-induced insulin release from pancreatic islets of rat and man was measured after 3 and 7 days of culture in media with or without clinically relevant concentrations of Escherichia coli L-asparaginase (0.01-100 U/mL). After culture, the remaining insulin, glucagon, and DNA in the islets were determined. After 7 days of culture of adult rat or human islets, both the accumulation of insulin in the medium and the content of insulin and glucagon in the islets were significantly reduced in the presence of 100 U/mL L-asparaginase compared with controls. Addition of 10(-6) M hydrocortisone to the culture medium enhanced this effect. In newborn rat islets a significant reduction in insulin release and content was observed already in the presence of 0.1 U/mL asparaginase, whereas the glucagon content was unchanged. Removal of the drug resulted in partial recovery of the insulin secretion. To elucidate the mechanisms of of action of the drug, insulin biosynthesis was studied in islets cultured in asparagine-free medium with or without asparaginase. No difference in biosynthesis was seen between media with or without asparagine, whereas 0.1 U/mL asparaginase caused about a 50% reduction under both conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

First-line diagnosis based on immunological phenotyping in suspected acute leukemia: a prospective study.

In a prospective analysis of the diagnostic value of immunophenotyping in acute leukemias (ALs), all patients admitted to a pediatric and a haematological department suspected of AL were examined consecutively with a selected panel of monoclonal antibodies (Mabs) against leucocyte differentiation antigens during an 8-month period. A total of 189 samples obtained from blood, bone marrow, spinal fluid and lymph nodes in 120 cases were all analysed blindly. The results were correlated with a routine morphological/cytochemical evaluation. Differing results were obtained in seven out of 38 cases in which the immunologically defined diagnosis was acute myeloid leukemia (AML), and in one out of 21 cases with the primary diagnosis acute lymphoid leukemia (ALL). Immunological phenotyping disclosed two cases of hybrid leukemia, one case of biphenotypic and one case of bilineal leukemia. No evidence of malignancy was found in 36 cases, 30 cases of blood and bone marrow and six cases of spinal fluids, in every case in accordance with the pathological examination. These results demonstrate that a first-line immunological evaluation of bone marrow, blood and spinal fluid from patients suspected of AL is highly capable of discriminating between different malignant and nonmalignant haematological diseases and also between various types of leukemias. The immunological methods do, however, require a sufficient amount of material which was a limiting factor in 14 out of 120 examinations, mainly from patients treated with several cycles of cytostatics. It is concluded that immunophenotyping can be used as a first-line diagnostic tool in malignant haematological diseases.

Acute Disease↗

Defective monocyte oxidative metabolism in a child with non-pneumonic legionellosis.

A case of non-pneumonic legionellosis with gastrointestinal manifestations is described in a 13-year-old boy without premorbidity. A selective defect in monocyte oxidative metabolism was found and consistently demonstrated throughout the following year. We suggest that the observed monocyte deficiency may have facilitated the development of legionnaires disease and that otherwise normal monocyte function may have contributed to the favourable course of disease.

Adolescent↗

Pre-exposure to glucagon impairs glucose recovery after insulin-induced hypoglycemia in man.

The effect of a two hour period of hypo- and hyperglucagonemia on a subsequent insulin-induced hypoglycemia was studied in nine healthy volunteers. Hypoglucagonemia was provoked by somatostatin (50 micrograms/h) and hyperglucagonemia by glucagon infusion (3.25 ng/kg/min) together with somatostatin, while saline alone was given as control. Hypoglycemia was induced by insulin infusion (2.4 U/h) for two hours. The hyperglycemic effect of glucagon was transient and similar nadir glucose levels were obtained in the three experiments. Preinfusion with glucagon impaired glucose recovery in spite of preserved secretion of epinephrine during restitution of blood glucose in this experiment. It is concluded, that a period of elevated glucagon levels deteriorates the restitution of blood glucose following hypoglycemia. Hyperglucagonemia, commonly apparent in poorly controlled diabetics, may therefore be of importance in explaining the impaired recovery of blood glucose seen in such patients after hypoglycemia.

Adult↗

Unusual immunophenotype displayed by histiocytes in haemophagocytic lymphohistiocystosis.

Extensive immunophenotypic studies in a 2 1/2 month old girl with haemophagocytic lymphohistiocytosis were performed to characterise the proliferating histiocytes of the disease. The cells strongly expressed conventional macrophage antigens, but unexpectedly, there was a dissociated expression of the CD1a antigen (reacting with the monoclonal antibody NA1/34 but not with OKT6) and intracellular S-100 protein by the haemophagocytic lymphohistiocytosis histiocytes. These findings indicate that there is a "hybrid" phenotype between the two main arms of the mononuclear phagocyte system--namely, Langerhans' cells and phagocytic macrophages.

Antibodies, Monoclonal↗

Pharmacokinetics of erythrocyte methotrexate in children with acute lymphoblastic leukemia during maintenance treatment.

The concentration of methotrexate (MTX) in erythrocytes (E-MTX) was measured in 47 children with acute lymphoblastic leukemia during maintenance treatment with MTX 1.7-21.6 mg/m2/week and 6-mercaptopurine 25-75 mg/m2/day. At the time of measurement the plasma MTX concentration was less than 2 nmol/l. The steady state E-MTX varied between 51 and 202 nmol/l erythrocytes. Alterations in the E-MTX took place over 8-12 weeks after a change in dosage. A significant correlation was found between the E-MTX and the weekly dose of MTX administered. Noncompliance was revealed in two patients. A very low E-MTX was found in one patients, probably caused by inhibition of erythropoiesis. No correlation was found between E-MTX and the total amount of MTX administered or the length of treatment. A terminal half-life of 2-5 weeks after discontinuation of the drug showed that the erythrocytes functioned as a slow-changing compartment for MTX. Unexpectedly low E-MTX could mean noncompliance, impaired erythropoiesis, altered metabolism, or poor drug absorption.

Absorption↗

The role of glucagon, catecholamines and cortisol in counterregulation of insulin-induced hypoglycemia in normal man.

To study the response of glucose counterregulation to insulin-induced hypoglycemia, six normals were given a 4-hour infusion of insulin (2.4 U/h) +/- somatostatin (50 micrograms/h). Supplementary glucagon (1.5 or 3.0 ng/kg/min) was given in additional experiments. In a separate study, glucagon was supplemented for 4 hours as a constant rate infusion (3.25 ng/kg/min) or at rates stepwise increasing from 1.5 to 5.0 ng/kg/min. Insulin decreased blood glucose by 1.5 mmol/l and simultaneous suppression of glucagon resulted in a more pronounced hypoglycemia enhancing the adrenaline and cortisol responses. The hyperglycemic effect of glucagon substitution (3 ng/kg/min) faded out after about 2 hours, whereafter exaggerated adrenaline and cortisol responses to hypoglycemia were seen. A comparison between the effects of steady state hyperglucagonemia and gradually appearing hyperglucagonemia on the counterregulation of hypoglycemia revealed no significant differences in glucose, adrenaline and cortisol responses to insulin. It is concluded that the glycemic effect of glucagon is transient in the hypoglycemic state. When the hepatic responsiveness to this hormone is decreased during hypoglycemia, adrenaline becomes the essential protective factor.

Adult↗

Effect of hyperthyroidism on fibre-type composition, fibre area, glycogen content and enzyme activity in human skeletal muscle.

Seven hyperthyroid patients were studied by repeated muscle biopsies (vastus lateralis) before and after a period of medical treatment which averaged 10 months. The biopsies were analysed with regard to fibre-type composition, fibre area, capillary density, glycogen content and enzyme activities representing the glycolytic capacity (hexokinase, 6-phosphofructokinase), oxidative capacity (oxoglutarate dehydrogenase, citrate synthase) and Ca2+- and Mg2+-stimulated ATPase in muscle. In the pretreatment biopsy (hyperthyroid state), there was a significantly lower proportion of type I fibres (30% vs. 41%), a higher capillary density (23%), lower glycogen content (33%), and higher hexokinase activity (32%) compared with the post-treatment biopsy. No significant changes in the activity of the remaining enzymes were observed. The present study indicates that hyperthyroidism induces a transformation from type I to type II fibres in human skeletal muscle. The increase in hexokinase activity probably reflects a higher glucose utilization by skeletal muscle in order to compensate partially for the reduced glycogen content.

Adult↗

A population study of severe aplastic anemia in children. Incidence, etiology and course.

The total number of registered cases of severe aplastic anemia in Denmark was 39 among children aged 0-14 years in 1967 to 1982 giving an annual incidence of 2.2 cases per 1 million children in a well defined and stable population. A probable cause of the aplastic anemia was found in 21 cases (54%). Exposure of the population to known etiological factors of aplastic anemia such as chloramphenicol, pesticides and hepatitis was constant in the study period, and accounted for 2, 5, and 2 cases, respectively. Other infections caused 6 cases, other drugs 2 cases, and organic diluents one case. Three children with constitutional aplasia developed severe aplastic anemia among a total of 6 Fanconi's anemias, 3 probable Fanconi's anemias, and 10 cases of erythrogenesis imperfecta diagnosed during the same 16 years. Thirteen patients (33%) died within 3 months after the diagnosis while on supportive treatment and low dose prednisolone supplemented with androgen treatment. Long term survival occurred in 10 patients (26%), of which 5 patients were in complete and 5 in partial remission.

Adolescent↗

Counterregulation of insulin-induced hypoglycaemia in primary hypothyroidism.

Hypothyroidism has been alleged to modulate insulin action and influence the secretion of growth hormone and catecholamines. We recently investigated the influence of hypothyroidism on glucose counter-regulatory capacity and the hormonal responses to insulin-induced hypoglycaemia in 6 patients with primary hypothyroidism (age 32-52 years, TSH-values 66-200 mU/l). Hypoglycaemia was induced in the hypothyroid state and again when the subjects were euthyroid. After an overnight fast a constant rate infusion of insulin (2.4 U/h) was given for 4 h. Glucose was measured every 15 min and insulin. C-peptide, glucagon, epinephrine, norepinephrine, growth hormone and cortisol every 30 min for 5 h. During insulin infusion somewhat higher concentrations of the hormone were obtained in the hypothyroid state and simultaneously glucose levels were 0.5 mmol/l lower. As expected, basal norepinephrine levels were higher in hypothyroidism. However, no increase in circulating norepinephrine during hypoglycaemia was registered in the two experiments. The responses of counterregulatory hormones showed an enhanced response of cortisol, similar responses of growth hormone and epinephrine while the glucagon response was paradoxically impaired. Our findings suggest that hypothyroidism alters insulin metabolism, and that the glucagon response to hypoglycaemia is impaired in this condition.

Adult↗

Folic acid supplements in vitamin tablets: a determinant of hematological drug tolerance in maintenance therapy of childhood acute lymphoblastic leukemia.

Methotrexate (MTX) is an antifolate that inhibits cell division by reducing intracellular amounts of reduced tetrahydrofolates. Of 53 children with acute lymphoblastic leukemia (ALL) in maintenance treatment with MTX and 6-mercaptopurine (6-MP), 25 had received daily folic acid supplements in vitamin tablets containing 75-200 micrograms folic acid for at least the preceding 3-month period. Experimental data have shown that increased folate concentrations intracellularly inhibit MTX metabolism and toxicity. Therefore we found it relevant to investigate the extent to which folic acid supplements affect hematological tolerance to MTX and 6-MP in children during maintenance therapy for ALL. The erythrocyte folate (ery-folate) concentration was significantly higher in children who received extra folic acid than in those who did not (p less than 0.001). The ery-folate in MTX-treated children was only marginally reduced compared with the controls. The erythrocyte methotrexate (ery-MTX) concentration correlated with the weekly dose of MTX but not with any of the investigated hematological parameters. Children who received vitamin tablets containing folic acid had higher thrombocyte counts (p = 0.0056), higher leukocyte counts (p = 0.06), higher neutrophil counts (p = 0.05), and lower erythrocyte mean cell volumes (p = 0.05) than children who received no folic acid. We conclude that folic acid supplements of 75-200 micrograms/day affect the proliferative capacity of the bone marrow. Since none of the children was folate deficient as judged by the ery-folate, we recommend that vitamins given to children in maintenance treatment with MTX and 6-MP for ALL should not contain folic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Antineoplastic Combined Chemotherapy Protocols↗

Malignant histiocytosis in childhood. Clinicopathological study of 4 cases.

Clinicopathological features of four paediatric cases of malignant histiocytosis (MH) are described. The patients all presented with fever, lymphadenopathy and anaemia. Two died from widespread disease within one month. Two patients, who received combination chemotherapy, were brought into remission and are currently without disease after 30 and 60 months, respectively. Diagnosis was made on the basis of infiltration by a mixture of anaplastic and well-differentiated phagocytic histiocytes in skin, lymph node, bone marrow and spleen. Immunohistochemical studies showed variable presence of lysozyme, alpha 1-antitrypsin (AT), and alpha 1-antichymotrypsin (ACT). Concanavalin A (Con A) receptors, recently suggested as a histiocyte marker, were found in the proliferating cells in all cases. S-100 protein was absent. The findings suggest that the prognosis in childhood MH remains guarded but not hopeless with aggressive combination chemotherapy. The presence of Con A receptors in paediatric MH cells with a more constant occurrence than lysozome, AT and ACT seems promising as an additional diagnostic tool although further studies are needed to examine the specificity of Con A receptors in relation to various other disorders of histiocytic proliferation.

Child↗

Effect of improved glycemic control by continuous subcutaneous insulin infusion on hormonal responses to insulin-induced hypoglycemia in type 1 diabetics.

Glucose counter-regulatory capacity and the hormonal responses to insulin-induced hypoglycemia were studied in eight type 1 diabetics before and after improvement of metabolic control by continuous subcutaneous insulin infusion (CSII). The intensified treatment resulted in a decrease in mean glycosylated hemoglobin from 11.6 +/- 0.5 to 9.3 +/- 0.4% within a mean period of 14 weeks. During a constant rate infusion of insulin (2.4 U/h), steady state levels of glucose appeared in all subjects. The steady state glucose level was identical before and after CSII. The counter-regulatory hormonal responses showed significantly higher epinephrine levels, while glucagon, growth hormone, and cortisol were not influenced. In parallel with the heightened epinephrine response the pulse rate response was significantly enhanced. The restitution of blood glucose after insulin hypoglycemia was not modified. It is concluded that a more vigorous catecholaminergic response to hypoglycemia is achieved after improved metabolic control by CSII.

Adult↗

Immunological markers in acute leukaemia.

61 acute leukaemias were classified by both immunological and morphological criteria. In 58 (95%) of the cases correlation was found between the immunological and morphological diagnosis. In 3 (5%) cases, no correlation was found between the immunological subclasses and the FAB-subgroups in ALL. Neither was a correlation found between FAB-subclasses in AML and reaction with myeloid antibodies other than MY-7 which did preferentially react with M4 and M5 leukaemia.

Adult↗