Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This ultrastructural study compared the endocytosis of a peptide hormone, ferritin-labeled insulin (Fm-I) or gold-labeled insulin (Au-I), and a non-hormonal ligand, gold-labeled alpha-2-macroglobulin-methylamine (Au-alpha 2MGMA), by rat adipocytes. Quantitative analysis of the cell surface showed that coated pits occupied 0.4% of the adipocyte surface. This was one fifth to one tenth of that which has been reported on fibroblasts and hepatocytes, cell types in which receptor-mediated endocytosis has been extensively studied. In contrast, uncoated micropinocytotic invaginations were quite numerous and occupied 13.1% of the adipocyte cell surface. The frequency of micropinocytotic invaginations, 13.8 per micron 2 of plasma membrane, was 7-12 times greater than has been reported on fibroblasts. Therefore, the ultrastructure of the endocytic apparatus on rat adipocytes was different from more commonly studied cell types. At 4 degrees C, Au-alpha 2MGMA concentrated within coated pits to a density that was 52 times greater than that on the uncoated plasma membrane. Au-alpha 2MGMA was excluded from micropinocytotic invaginations by more than 93%; this exclusion was unrelated to the size of the Au-alpha 2MGMA particle. In contrast, at 4 degrees C, Fm-I did not concentrate within coated pits and occupied micropinocytotic invaginations in a random manner. At 37 degrees C, coated pits accounted for all of the endocytosis of Au-alpha 2MGMA, proving that these structures were functional despite their atypically low density. In contrast, greater than 99% of the endocytosis of Fm-I or Au-I occurred through micropinocytotic invaginations. These results demonstrated for the first time by a comparative, quantitative, ultrastructural method that insulin and Au-alpha 2MGMA undergo endocytosis by dissimilar mechanisms on rat adipocytes. Dissimilarities in the endocytosis of insulin and Au-alpha 2MGMA may be related to the different biological roles of these two molecules.
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PMID:Insulin and alpha 2-macroglobulin-methylamine undergo endocytosis by different mechanisms in rat adipocytes: I. Comparison of cell surface events. 244 62

We studied pituitary-gonadal function in 11 male and 5 female patients, aged 12-30 yr, with severe beta-thalassemia and chronic iron overload. All had normal basal serum cortisol, T4, and PRL concentrations and normal serum cortisol and GH responses to insulin-induced hypoglycemia and TSH responses to TRH. Of the 11 male patients (all over 17 yr of age), only 3 attained full pubertal development and 4 had subnormal serum LH and FSH responses to GnRH. As a group, their mean basal serum testosterone (T) level was low [11.7 +/- 4.9 (+/- SE) nmol/L; normal, 10-40 nmol/L], and 9 of the 11 male patients responded to hCG with a rise in serum T. Two of the 3 female patients over 17 yr of age were prepubertal with undetectable serum estradiol (E2) levels and absent serum LH and FSH responses to GnRH; the other female patient had regular menstrual cycles and normal serum E2 levels and LH and FSH responses to GnRH. Six of the prepubertal patients (4 males and 2 females, aged 17-30 yr) were studied serially for 3 yr after the start of chelation therapy. Despite a fall of median serum ferritin from 11,910 to 1,303 pmol/L, there was no progression of puberty, and their basal and GnRH-stimulated serum LH and FSH and serum T or E2 levels did not change. Three of these patients (1 male and 2 female) then received pulsatile sc GnRH therapy in addition to chelation therapy for 6 months with no improvement. We conclude that chronic iron overload in patients with severe thalassemia leads to variable degrees of hypogonadotropic hypogonadism, which do not respond to chelation therapy given late in the course of the disease. The hypogonadism in most patients was due to pituitary hyporesponsiveness to GnRH.
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PMID:Hypogonadotropic hypogonadism in severe beta-thalassemia: effect of chelation and pulsatile gonadotropin-releasing hormone therapy. 249 34

We examined the adrenocortical function in 14 italian thalassemic patients (8 f., 6 m.) aged 12 to 28. The following hormones were determined in each subject: plasma cortisol and aldosterone levels in both basal conditions and after maximal and submaximal stimulus (250 and 5 micrograms respectively) with synthetic corticotrophin beta 1-24 (Synacthen Ciba); corticotrophin and cortisol response to insulin-induced hypoglycaemia (0.15 U/kg iv.). Tests were repeated in all patients four years later. Normal controls were a group of 10 normal subjects matched for age, sex and body mass. Normal basal values of cortisol, aldosterone and ACTH were observed. Impaired cortisol response after stimulation with 5 micrograms of ACTH (6 patients) and after hypoglycaemia (4 patients) was identified. At the second test, four years later, one patient showed impaired cortisol response to both ACTH (5, micrograms) and hypoglycaemia, unlike the normal response to the first test. In all the others the cortisol response to stimulation did not differ from previous ones. In conclusion reduced ACTH and cortisol reserves detected in some thalassemic patients may be related to iron infiltration in the pituitary and adrenal glands. However, the present study did not indicate any significant correlation between either total blood load or serum ferritin and adrenal function parameters. Alteration in circulating hormones catabolism and impaired synthesis of transport proteins caused by chronic liver disease made adrenocortical hypofunction an even more complex picture to understand.
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PMID:Hypothalamic pituitary adrenal function in patients with thalassemia major. 255 55

Neonatal polycythemia is a perinatal complication in infants of diabetic mothers. The cord CBC (complete blood counts), serum iron, transferrin and ferritin concentrations were studied in newborn infants of 9 GDM (gestational diabetes), 21 NIDDM (noninsulin-dependent diabetes mellitus), and 8 IDDM (insulin-dependent diabetes mellitus) mothers. The RBC (red blood cell) count, Hb (hemoglobin) and Hct (hematocrit) of these infants were higher than control infants. There was no difference between the serum iron concentration of the infants of each group diabetic mothers and the infants in the control group, but the transferrin concentration was significantly higher and the ferritin was significantly lower in the infants of diabetic mothers than in those of control mothers. There was a significant negative correlation between transferrin and ferritin (r = -0.491 p less than 0.001). Erythropoiesis is considered to be enhanced in the fetuses of diabetic mothers, and the iron needed for erythropoiesis is reportedly transported from the mother to the fetus according to the demands of the fetus, but the iron storage was shown to be reduced in the fetuses of diabetic mothers.
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PMID:Cord transferrin and ferritin values for erythropoiesis in newborn infants of diabetic mothers. 263 11

Iron-chelating treatment is indicated in all children on prolonged transfusion therapy (i.e., chiefly patients with thalassemia and Blackfan-Diamond anemia). The purpose of iron-chelating treatment is to prevent the development of manifestations of iron overload including cardiac hemosiderosis and insulin-dependent diabetes mellitus (which are two potentially fatal complications), hepatic cirrhosis, hypoparathyroidism, hypothyroidism, and delayed puberty. Deferoxamine is the only effective iron-chelating agent and should be given in a daily dose of 40 mg/kg at initiation of the transfusion program. Administration is by subcutaneous infusions from 8 to 10 hours per day. The goal of iron-chelating treatment is to maintain serum ferritin levels between 500 and 1,000 ng/ml. This long-term treatment is a significant burden for patients and it can be hoped that non-toxic iron-chelating agents, active by mouth, will become available.
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PMID:[Iron chelation in children]. 268 51

Serum ferritin and diabetes control were evaluated in 18 White patients with poorly controlled type II (non-insulin-dependent) diabetes who had no known causes of iron-storage disorder. Serum ferritin levels were found to be elevated with normal serum iron and total iron-binding capacity in 9 of the 18 patients studied. Because excess iron, typified by hemochromatosis, is associated with diabetes, and diabetes has been shown to improve after lowering total-body iron load through repeat venesection, I investigated whether regulating elevated ferritin levels could facilitate diabetes control. Deferoxamine (DFO), a known specific chelator of iron, was used because of its capacity to correct excess iron stores. All 9 patients in the high-ferritin diabetic group and 7 of 9 diabetic control subjects with normal serum ferritin levels were given DFO (10 mg/kg i.v.) twice weekly. Diabetic control, fasting glucose, triglyceride, cholesterol, HbA1c, and serum ferritin levels were monitored. Data show that lowering elevated ferritin levels correlated well with diabetes control and improved fasting glucose, triglyceride, and HbA1c in 8 of 9 patients with high ferritin levels. Lowering normal ferritin levels had no effect on diabetes control or on any of the other parameters in the 7 control subjects. This study shows there is a need to study iron metabolism in poorly controlled diabetes and demonstrates the value of DFO in controlling high-ferritin diabetes.
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PMID:Deferoxamine therapy in high-ferritin diabetes. 279 74

Oral glucose tolerance tests were conducted in 29 patients with aplastic anemia and 20 nondiabetic controls. Seventeen were men and 12 were women, ranging in age from 15 to 67 years. Based on the results of oral glucose tolerance test, the patients were divided into three groups: 14 previously treated cases with normal glucose tolerance; eight previously treated cases with abnormal glucose tolerance, of whom six had diabetes and two had impaired glucose tolerance; and seven newly diagnosed cases with normal glucose tolerance. Hyperinsulinemia and insulin resistance were observed in all patients. Multivariate analyses show that sex, age, body mass index, previous androgen and corticosteroid therapy, previous blood transfusion, initial hemoglobin and white blood cell and serum ferritin concentrations were not significantly related to hyperinsulinemia as expressed by the integrated insulin area under the curve of glucose tolerance test. Patients in the second group who had abnormal glucose tolerance had a delay in insulin secretion in response to glucose, indicating a deterioration of insulin reserve in the beta cells. Patients in this group were significantly older at the time of diagnosis than those in the first group. No other determinants of the development of abnormal glucose tolerance were demonstrated.
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PMID:Glucose intolerance, hyperinsulinemia and insulin resistance in aplastic anemia. 291 40

Thirteen men and one woman (mean age 48.8 yr +/- 6.9, range 36-63) with idiopathic hemochromatosis were treated by erythrocytapheresis. Iron depletion followed 9.60 months treatment (median 24), with 21-203 erythrocytaphereses (mean 93 +/- 61) and total iron removal of 4.2-40.6 g (mean 19 +/- 11.9). Trasferrin saturation decreased from 90 +/- 8.7% to 17 +/- 10.6% and serum ferritin from 3164 micrograms/L +/- 1488 to 60.5 micrograms/L +/- 77.5, and liver iron content normalized in all cases. Initial serum ferritin in the patients who were iron-depleted at 18 months (50%, cumulative percentage) was significantly lower than in those still iron loaded at that time (2280 micrograms/L +/- 940 vs 4049 micrograms/L +/- 1444, p less than 0.02). Clinical improvement was noted in all cases with about a 30% decrease in insulin requirement in most diabetics. Thus erythrocytapheresis appears to be effective and safe in obtaining iron depletion in idiopathic hemochromatosis.
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PMID:Effectiveness of erythrocytapheresis in idiopathic hemochromatosis. Report of 14 cases. 292 63

Dietary supplementation with high-carbohydrate, guar gum fiber (HCF) is effective in acutely blunting postprandial blood glucose levels. We report the effect of such supplementation on the diet and nutritional status of a group of 16 subjects with non-insulin-dependent diabetes mellitus (NIDDM) who incorporated either HCF bars (35.7 g carbohydrate and 6.6 g guar gum/bar) or placebo bars (identical except for the absence of guar gum) into the diet for 6 mo as part of a double-blind, randomized clinical trial. The HCF subjects achieved mean daily intake of 4.8 +/- 0.4 bars, constituting 51.2 +/- 3.1% of total calories and providing 29.7 +/- 2.6 g guar gum daily. Energy intakes and body weight did not change significantly in either group. Food consumption patterns and nutrient intakes did change, although not enough to impair the nutritional integrity of the diet because the bars themselves served as a source of nutrients. The bars were rich in thiamin, B6, folacin, phosphorus, iron, zinc, and copper, adequately replacing any decrease in nutrient intake as a result of foods being dropped from the diet. In fact, daily intakes of B6, folacin, and copper actually increased due to contributions from the bars. Nutrients in which the bars were poor (vitamins A, C and B12) resulted in suboptimal intakes (less than 66% RDA). Although no significant change in nutritional status of the HCF group occurred as determined by arm muscle area, arm fat area, hemoglobin, hematocrit, or serum albumin, transferrin, iron, ferritin, calcium, phosphate, B12, and magnesium levels, these indicators of nutritional status are rather insensitive.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Nutritional risk of high-carbohydrate, guar gum dietary supplementation in non-insulin-dependent diabetes mellitus. 302 7

To test the hypothesis that deficiencies in hypothalamic-pituitary function in genetic hemochromatosis result from cellular injury by iron deposits, we conducted provocative tests in 11 men with genetic hemochromatosis before and after iron depletion by serial phlebotomy and in 10 control subjects. We gave combination intravenous injections of insulin (0.15 U/kg), luteinizing hormone releasing hormone (LHRH, 100 micrograms), and thyrotropin releasing hormone (400 micrograms) and then measured plasma glucose, growth hormone, corticosteroids, follicle-stimulating hormone, luteinizing hormone, prolactin, and thyroid-stimulating hormone at 30-minute intervals for 90 minutes. Phlebotomy caused a substantial decrease in median values for serum ferritin, deferoxamine-chelatable iron, and hepatic iron concentration. Before phlebotomy, stimulation by hypoglycemia and thyrotropin releasing hormone caused significantly less secretion of growth hormone (P = 0.004) and prolactin (P = 0.03) in patients than in control subjects. No significant improvement was noted, however, in growth hormone or prolactin secretion after phlebotomy. Of the 11 patients, 7 had secondary hypogonadism, and phlebotomy did not improve the serum testosterone, follicle-stimulating hormone, luteinizing hormone, or responses to LHRH in any case. Chlorpromazine injections failed to elevate serum prolactin in all patients, and administration of levodopa caused a partial reduction in serum prolactin; thus, the hypothalamus may be an important locus of endocrine malfunction in these patients. We conclude that abnormal hypothalamic-pituitary function in genetic hemochromatosis is not substantially improved by iron-depletion therapy.
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PMID:Influence of phlebotomy treatment on abnormal hypothalamic-pituitary function in genetic hemochromatosis. 310 26


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