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G Bergamaschi

Publications and source records attributed to G Bergamaschi.

At least 73 records · Page 4Linked to original sources
PubMed1988

The behavior of asialotransferrin-iron in the rat.

The effect of desialylation of rat and human transferrins on hepatocyte processing of the protein and its iron was studied in rats. No alteration in early transferrin catabolism was observed. Radioiron disappearance from the plasma and liver iron uptake were more rapid for asialotransferrins than for normal transferrins (P less than .001). Furthermore, radioiron plasma clearance of human tri-sialotransferrin was faster (P less than .05) and liver uptake higher (P less than .002) than for human pentasialotransferrin. When the asialoglycoprotein receptor was blocked by the prior injection of asialofetuin, asialotransferrin behaved like normal transferrin. When the transferrin receptor was blocked by the prior injection of 50 mg human diferric transferrin, iron uptake from all transferrins was delayed to such an extent that uptake through both receptors seemed to be affected. Approximately 90% of the hepatic radioiron from all transferrins was chelated by desferrioxamine and excreted into the bile, indicating its uptake by the hepatocyte rather than the reticuloendothelial (RE) cell. The rate of iron release into the plasma and its subsequent accumulation in the red cell mass over a 2-week period was similar for human asialotransferrin, ferritin, and hemoglobin iron. This study 1) confirmed that asialotransferrin-iron uptake by the hepatocyte is mediated by both transferrin and asialoglycoprotein receptors; 2) demonstrated that not only asialotransferrin but also transferrin of low sialic acid content will increase iron turnover and lead to excessive iron loading of the hepatocyte; 3) and showed that the intrahepatocyte metabolism of asialotransferrin-iron did not differ from that of iron delivered by normal transferrin.

Animals↗
PubMed1988

Effects of recombinant human H-subunit and L-subunit ferritins on in vitro growth of human granulocyte-monocyte progenitors.

We have studied the influence of purified recombinant human H-subunit (rHF, acidic) and L-subunit (rLF, basic) ferritins on in vitro colony formation by normal human granulocyte-macrophage progenitor cells (CFU-GM). Whereas rLF had no significant effect, rHF produced significant decrease in colony formation: mean inhibition of CFU-GM was 38% +/- 13% at 10(-8) M and 22% +/- 13% at 10(-9) M. The inhibitory activity of rHF was lost at 10(-10) M, and was inactivated with a monoclonal antibody recognizing the H subunit, but not with a monoclonal antibody recognizing the L subunit. Although H-type isoferritins were found in normal and leukaemic cells, their concentration in peripheral blood plasma and bone marrow plasma from normal subjects and patients with different haematological disorders including acute leukaemia were 10(-11) M or lower, i.e. levels showing no activity in vitro. We conclude that: (i) acidic H-subunit-rich isoferritins have inhibitory effects on in vitro growth of granulocyte-macrophage progenitors; (ii) levels of these isoferritins in peripheral blood and bone marrow plasma are 2-3 orders of magnitude lower than the effective concentrations in vitro, indicating that these molecules do not behave as circulating regulatory or suppressive factors in vivo.

Bone Marrow Cells↗
PubMed1988

Killing of K562 cells with conjugates between human transferrin and a ribosome-inactivating protein (SO-6).

Cellular iron uptake is mediated by binding of transferrin with specific surface receptors and internalization of the Fe-transferrin-receptor complex. This has been examined as a possible pathway for carrying into leukaemic cells a ribosome-inactivating protein (RIP), SO-6, derived from Saponaria officinalis. Purified human differic transferrin was conjugated with SO-6 and a pool of proteins was obtained, with variable numbers of SO-6 molecules linked to a single transferrin molecule. Human erythroleukaemic K562 cells were grown in the presence of human transferrin, SO-6 and human transferrin conjugated with SO-6. The conjugate was found to be internalized via binding with transferrin receptor. Whereas the presence of unconjugated human transferrin and SO-6 in the medium did not significantly influence K562 cell growth, the conjugated proteins displayed an inhibitory activity on cell proliferation. This was maximal after 72 h at a transferrin concentration of 10(-9) M, with about 50% of cells being killed. Bovine transferrin, present in fetal calf serum, did not appear to compete with human diferric transferrin in binding to K562 cells in suspension culture. In a clonogenic assay, colony formation by leukaemic cells was not influenced by free SO-6 or transferrin, whereas the conjugated proteins were markedly inhibitory (about 100% at 10(-9) M). Our findings indicate that SO-6 can be efficiently carried into mammalian cells via the transferrin-transferrin receptor cycle and exert its ribosome inactivating activity. This is in keeping with the existence of an alternative pathway of transferrin endocytosis in addition to the classic acidic endosome pathway. From a practical viewpoint, conjugates between transferrin and SO-6 can be useful tools for studying the expression of transferrin receptors, and deserve also to be investigated for a possible use in cancer therapy.

Humans↗
PubMed1988

Recombinant gamma-interferon induces in vitro monocytic differentiation of blast cells from patients with acute nonlymphocytic leukemia and myelodysplastic syndromes.

gamma-Interferon (IFN-gamma) has previously been found to induce monocytic differentiation in established leukemic cell lines, such as HL-60 and U937. The aim of the present study was to evaluate the differentiative effect of highly purified recombinant (r)IFN-gamma on fresh bone marrow cells from patients with acute nonlymphocytic leukemia (n = 11) or myelodysplastic syndromes (n = 3). Blast cells were cultured in suspension in the presence or absence of rIFN-gamma (10-10(3) U/ml). While 6 out of 14 cases were unresponsive to rIFN-gamma in vitro, the remaining 8 patients showed a significant increase (0.05 greater than p greater than 0.001) in the percentage of cells expressing C3bi receptors, detected by OKM1 (median value in control cell, 9.5; median value in rIFN-gamma-treated cells, 31) and Mo1 (8.5 vs. 36), and in the percentage of cells expressing the monocytic antigens detected by Mo2 (8 vs. 28) and MY4 (6.5 vs. 32.5). In the responsive patients morphologic changes consistent with monocytic maturation, as well as a strong increase of alpha-naphthyl acetate esterase activity and of nitroblue tetrazolium reducing capability were observed upon culture with rIFN-gamma. We conclude that (a) rIFN-gamma may induce in vitro monocytic differentiation of blasts from acute nonlymphocytic leukemia and myelodysplastic syndrome patients, and that (b) this agent should be investigated for its capacity to be active in vivo.

Acute Disease↗
PubMed1988

Synergistic antiproliferative effect of recombinant interferon-gamma with recombinant interferon-alpha on chronic myelogenous leukemia hematopoietic progenitor cells (CFU-GEMM, CFU-Mk, BFU-E, and CFU-GM).

Recombinant interferons, alpha (rIFN-alpha) and gamma (rIFN-gamma), have been demonstrated to have significant antitumor activity as single agents in the treatment of chronic myelogenous leukemia (CML). Due to their possible synergistic efficacy, a combination rIFN therapy in CML has been proposed. To establish a biologic basis for this, we have studied the suppressive effects of rIFN-alpha and rIFN-gamma on the in vitro growth of CML-derived progenitor cells (CFU-GEMM, CFU-Mk, BFU-E, CFU-GM), the optimal conditions for rIFN synergism, and the possible role of hematopoietic accessory cells (T-lymphocytes and monocytes-macrophages) in mediating rIFN-induced growth inhibition. When added to unseparated bone marrow cells, rIFN-alpha and rIFN-gamma significantly reduced colony formation, with 50% inhibition occurring at 71 and 186 U/mL for CFU-GEMM, 40 and 152 U/mL for CFU-Mk, 222 and 1,458 U/mL for BFU-E, and 119 and 442 U/mL for CFU-GM, respectively. A small amount of rIFN-gamma (5 U/mL) acted synergistically with increasing doses of rIFN-alpha, and the values of 50% inhibitory concentrations fell outside the lower limit (10 U/mL) used in our experiments. This synergy was evident even when rIFN-gamma was added 72 hours after the initiation of cultures; however, it was completely lost when the target cells were depleted of accessory cells. When a low dose of rIFN-alpha (5 U/mL) was added to rIFN-gamma, the 50% inhibitory concentration values were decreased up to tenfold. These studies (1) confirm that CML-derived hematopoietic progenitors are responsive to the suppressive activity of both rIFN-alpha and rIFN-gamma in vitro, (2) demonstrate that different mechanisms are responsible for the suppressive activity of the two rIFNs, and (3) characterize their synergistic interaction, providing a basis for future clinical trials aimed at investigating combination rIFN therapy in CML.

Bone Marrow↗
PubMed1987

Pathophysiological classification of acquired bone marrow failure based on quantitative assessment of erythroid function.

Bone marrow failure encompasses a broad spectrum of disorders including aplastic, dysmyelopoietic and myelophtisic anemias. In the present study, these anemias were characterized according to the degree of erythroid proliferation and efficiency of erythropoiesis. Total erythropoietic activity was evaluated in 43 patients by measuring the erythron transferrin uptake (ETU). It averaged 20% of basal (range 3-43%) in 13 patients with severe aplastic anemia, 75% of basal (range 60-103%) in 3 patients with extensive bone marrow infiltration by neoplastic cells, 131% of basal (range 50-217%) in 16 patients with refractory anemia, and 452% of basal (range 63-720) in 11 patients with idiopathic refractory siderobastic anemia. Respective efficiencies of erythropoiesis were 74% in aplastic anemia, 70% with bone marrow infiltration, 46% in refractory anemia, and 14% in sideroblastic anemia. Based on the ETU, patients could be categorized into absolute marrow failure, relative marrow failure, and adequate erythropoietic response to anemia. This simple determination of proliferating activity of the erythroid marrow can provide useful information on the pathophysiology of marrow failure and a basis for the selection of therapeutic approaches.

Adolescent↗
PubMed1987

Adequacy of iron supply for erythropoiesis: in vivo observations in humans.

The adequacy of tissue iron supply was examined with ferrokinetic techniques in subjects with decreased plasma iron concentration and in subjects with a normal plasma iron concentration but with increased tissue iron requirements. The competition by transferrin receptors for diferric vs monoferric transferrin was measured in eight normal persons and eight with iron deficiency. There was a highly significant (P less than 0.001) decrease in receptor preference for diferric transferrin in subjects with iron deficiency, indicating an insufficient amount of iron-bearing transferrin to saturate tissue receptors. The adequacy of the plasma iron supply was also examined by determining the number of iron-bearing transferrin molecules with receptors at normal and elevated plasma iron concentrations. Significant increases were found at the higher plasma iron concentration, not only in patients with iron deficiency, but also in patients with sickle cell anemia and thalassemia. Furthermore, the increase in the latter two groups was shown to be proportional to the degree of erythroid hyperplasia. These data indicate that tissue iron supply must be evaluated in terms of both plasma iron supply and erythropoietic requirements and that a relative iron deficiency is frequent in patients with erythroid hyperplasia.

Anemia, Hypochromic↗
PubMed1986

The effect of transferrin saturation on internal iron exchange.

Radioiron was introduced into the intestinal lumen to evaluate absorption, injected as nonviable red cells to evaluate reticuloendothelial (RE) processing of iron, and injected as hemoglobin to evaluate hepatocyte iron processing. Redistribution of iron through the plasma was evaluated in control animals and animals whose transferrin was saturated by iron infusion. Radioiron introduced into the lumen of the gut as ferrous sulfate and as transferrin-bound iron was absorbed about half as well in iron-infused animals, and absorbed iron was localized in the liver. The similar absorption of transferrin-bound iron suggested that absorption of ferrous iron occurred via the mucosal cell and did not enter by diffusion. The decrease in absorption was associated with an increase in mucosal iron and ferritin content produced by the iron infusion. An inverse relationship (r = -0.895) was shown between mucosal ferritin iron and absorption. When iron was injected as nonviable red cells, it was deposited predominantly in reticuloendothelial cells of the spleen. Return of this radioiron to the plasma was only 6% of that in control animals. While there was some movement of iron from spleen to liver, this could be accounted for by intravascular hemolysis. Injected hemoglobin tagged with radioiron was for the most part taken up and held by the liver. Some 13% initially localized in the marrow in iron-infused animals was shown to be storage iron unavailable for hemoglobin synthesis. These studies demonstrate the hepatic trapping of absorbed iron and the inability of either RE cell or hepatocyte to release iron in the transferrin-saturated animal.

Animals↗
PubMed1985

Immunological reactivity of serum ferritin in patients with malignancy.

Serum ferritin has been suggested as a tumor marker in the diagnosis of certain malignancies and for following the activity or dissemination of the malignant process. Since neoplastic tissues generally contain more acidic isoferritins than their normal tissue counterparts, it has also been suggested that the specific assay of such isoferritins in serum may be of particular value in the diagnosis of malignancy. In this work, we have evaluated ferritin concentration in the serum of normal subjects and patients with acute nonlymphocytic leukemia, Hodgkin's disease, breast cancer and lung cancer by simultaneously using three different immunoassays: an immunoradiometric assay based on polyclonal antibodies against human liver (basic, L-subunit rich) ferritin, a radioimmunoassay based on polyclonad antibodies against HeLa cell (acidic, H-subunit rich) ferritin, and an immunoradiometric assay based on the monoclonal antibody 2A4 raised against human heart (acidic, H-subunit rich) ferritin. Most of the patients studied had increased values for liver-type ferritin in the absence of increased iron stores. Binding of serum ferritin to concanavalin A did not prove to be useful in distinguishing a tumor-specific basic isoferritin. The HeLa ferritin assay was found to be less specific than the heart ferritin assay in the detection of acidic isoferritins, and did not provide any advantage over the liver assay in detecting the increased levels of serum ferritin associated with malignant disease. Heart-type ferritin was found in one-fifth of normal sera and 64% of sera from patients with malignancy. Values were very low compared with those for basic ferritin, ranging from less than 0.1 to 17% of total serum ferritin (geometric mean value 1.3%) in patients with malignancy. These findings indicate that at present there is little application for serum ferritin immunoassays based on antibodies to HeLa cell or heart ferritin in the diagnosis or monitoring of malignant disease. This seems to be due to the presence in human serum of biding factors which are responsible for the rapid clearance of acidic isoferritins from the circulation. The serum concentration of basic ferritin, however, can be useful in the diagnosis and management of some malignancies, and it is possible that studies on cell isoferritins can be important in biologic monitoring of neoplastic disorders. It should also be noted that the increased levels of serum ferritin found in patients with malignancy can exert adverse effects on the host immune response and perhaps an inhibitory effect on hematopoiesis.

Antibodies, Monoclonal↗
PubMed1985

Use of a monoclonal antibody against human heart ferritin for evaluating acidic ferritin concentration in human serum.

Immunoassays for acidic ferritins rich in H subunits have shown that these isoferritins are predominant in some cells such as monocytes and red blood cells but have provided conflicting results about their presence in human serum. We have used an immunoradiometric assay based on a monoclonal antibody against human heart ferritin (monoclonal 2A4) for evaluating acidic ferritin concentration in human serum. This assay proved to be highly specific for acidic isoferritins having more than 60% H subunits. Heart-type ferritin was detected in only one fifth of normal sera and sera from patients with iron overload; values were very low compared with those for basic ferritin. Acidic ferritin was found in relatively high concentrations in most patients with iron deficiency anaemia. In other disease states characterized by increased serum concentrations of basic ferritin, acidic ferritin was always less than 21% of the total ferritin. Dialysis in low-ionic-strength buffer showed that both normal and pathological sera had binding factors for human heart ferritin. We conclude that: (i) human serum contains low concentrations of acidic isoferritins which, at variance with basic ferritin, do not appear to be directly related to the amount of storage iron; (ii) the findings of the present study reinforce the opinion that basic and acidic ferritins have different functional behaviours.

Anemia, Hypochromic↗
PubMed1983

Basic and acidic isoferritins in the serum of patients with Hodgkin's disease.

Ferritin concentration has been measured in the serum of patients with Hodgkin's disease (HD) by radioimmunoassays with monospecific antibodies to liver (basic) and HeLa (acidic) ferritin. Elevated levels of serum ferritin with the liver ferritin assay were found only in patients with systemic disease, and were associated with low serum iron. Basic ferritin levels returned promptly to normal when complete remission was achieved. High levels of serum ferritin with the HeLa ferritin assay were found in 94% of all untreated patients. Acidic ferritin concentration was not related to systemic symptoms or alterations of iron metabolism, and returned to within the normal range only 1-2 yr after complete remission. These findings suggest that basic and acidic isoferritins can be distinguished in terms of biological and clinical significance. Basic ferritin is synthesized by the reticuloendothelial cells and the high values found in patients with systemic symptoms are compatible with the non-specific changes known to occur in the reticuloendothelial system during inflammation. In patients with untreated HD an elevated serum concentration of basic ferritin can be considered a marker of systemic symptoms and, therefore, an unfavourable prognostic factor. Acidic ferritin may be derived from abnormal lymphocytes and/or monocytes, including malignant cells, and its serum concentration may be of value in following the course of remission.

Adolescent↗
PubMed1983

Iron loading in congenital dyserythropoietic anaemias and congenital sideroblastic anaemias.

The relationship between body iron status, degree of anaemia, erythroid expansion, age and sex has been studied in eight patients with congenital dyserythropoietic anaemia (CDA) and two patients with congenital sideroblastic anaemia, who had received no or very few blood transfusions and no medicinal iron during the course of their illness. All patients had increased iron stores. Iron load was mild in three women in the reproductive age and severe in two men, in middle age, who had evidence of parenchymal organ dysfunction. Iron loading, as judged by the plasma ferritin concentration, was independent of the degree of anaemia while it was closely related to the patient's age and the degree of increase in the total erythropoietic activity. It is concluded that patients with CDA or congenital sideroblastic anaemia are at high risk of developing haemochromatosis in middle age. Prophylactic phlebotomy or iron chelation therapy should be considered for such patients.

Adolescent↗
PubMed1983

Ferritin in the red cells of normal subjects and patients with iron deficiency and iron overload.

Red cell ferritin was measured in normal subjects and patients with iron deficiency and iron overload by means of radioimmunoassays with antibodies to liver (basic) and heart (acidic) ferritins. In most of the subjects examined, red cells were found to contain greater amounts of heart-type than liver-type ferritin. The basic ferritin content reflected the abnormal body iron status both in iron deficiency and iron overload while the acidic ferritin content was less closely related to the iron status. The two immunologically different red-cell ferritins probably represent distinct ferritin molecules and may have different metabolic functions within haem-synthesizing erythroid cells.

Anemia, Aplastic↗
PubMed1983

Internal distribution of excess iron and sources of serum ferritin in patients with thalassemia.

Liver and spleen iron concentrations, serum ferritin level and binding of S-ferritin to concanavalin A (Con A) were measured in 12 patients with thalassaemia major or intermedia at the time of splenectomy. All these subjects had increased liver iron concentration, most of them had hepatic fibrosis but none of them had histological evidence of chronic hepatitis. No patient had ascorbic acid deficiency. Serum ferritin concentration was increased in all cases, ranging from 266 to 5504 micrograms/l. In all but 2 subjects most of the protein did not bind to Con A, thus behaving as tissue ferritin. There were highly significant correlations between serum ferritin concentration, amount of blood transfused and liver iron concentration. On the average, iron concentration in the liver was about 3 times that in the spleen. The findings obtained suggest that in patients with thalassaemia major or intermedia most of the iron is deposited in parenchymal tissues and most of the S-ferritin derives by leakage from the cytosol of iron-loaded parenchymal cells. S-ferritin is a valid index of liver iron overload in thalassaemic patients without complications such as viral hepatitis and/or ascorbic acid deficiency.

Blood Transfusion↗
PubMed1983

Biologic and clinical significance of red cell ferritin.

Red cell ferritin was measured in normal subjects and patients with disorders of iron metabolism, inflammation, liver dysfunction, impaired hemoglobin synthesis, and increased red cell turnover by means of radioimmunoassays with antibodies to liver (basic) and heart (acidic) ferritins. The normal mean values for basic and acidic ferritin were 8.9 and 22.7 altogram (ag)/cell, respectively. The red cell ferritin content reflected changes occurring in tissues both in iron deficiency and iron overload. Basic ferritin was more closely related to the body iron status than acidic ferritin, and the acidic/basic ferritin ratio was increased in iron deficiency and decreased in iron overload. The major factor determining the red cell ferritin content appeared to be the transferrin saturation, that is, the distribution of iron between monoferric and diferric transferrin. This is in keeping with recent data indicating a competitive advantage of diferric transferrin in delivering iron to erythroid cells. In addition, the red cell ferritin content was increased in thalassemic patients with normal iron status, appearing to be inversely related to the rate of hemoglobin synthesis. The determination of red cell ferritin, based on a commercially available basic ferritin assay, can have clinical application. It can be used for evaluating the adequacy of the iron supply to the erythroid marrow, particularly in patients with increased red cell turnover. Moreover, it may be useful in evaluating the body iron status in patients with hemochromatosis and liver disease.

Adolescent↗
PubMed1982

Kaposi's sarcoma complicating immunosuppressive therapy for angioimmunoblastic lymphadenopathy with dysproteinemia.

Cutaneous and visceral dissemination of Kaposi's sarcoma (KS) occurred in a patient with angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) who had been treated with combination chemotherapy. Three other cases of KS complicating immunosuppressive therapy of AILD have been reported in the literature, and there is evidence to indicate that AILD displays features which are known to predispose to KS. Like in other subjects with profound immunodeficiency (e.g. in young homosexual men), in our patient KS pursued an unusually aggressive course, with involvement of lymph nodes and internal organs as well as the skin. It is concluded that the risk of developing severe KS is a further reason to avoid aggressive combination chemotherapy in patients with AILD, particularly in those of Jewish or Mediterranean ancestry. Even the use of corticosteroids should be reduced to a minimum to avoid immunosuppression, and a conservative approach to treatment seems advisable.

Aged↗
PubMedDate not supplied

Evaluation of erythroid marrow response to recombinant human erythropoietin in patients with cancer anaemia.

BACKGROUND: Anaemia is a frequent finding in patients with cancer and may be due to different causes, including blunted erythropoietin production. MATERIALS AND METHODS: In a pilot study, we administered recombinant human erythropoietin (rHuEPO) to twelve patients with solid tumours and secondary anaemia. rHuEPO was given subcutaneously 5 d per week at escalating doses (75 to 150 U/kg per day): the aim of treatment was a Hb level > or = 10 g/dl without blood transfusion. We evaluated endogenous EPO production through serum EPO levels and erythroid marrow activity by means of serum transferrin receptor (TfR). RESULTS: Six out of 12 subjects had defective endogenous EPO production. All patients but two responded to treatment with steady increases in Hb levels above 10 g/dl, and the median dose of rHuEPO required for correction of anaemia was 75 U/kg. Response was associated with an early increase in serum TfR. Six patients developed functional iron deficiency and required iron supplementation to obtain response. Treatment improved functional ability in 4/10 responders. CONCLUSIONS: Subcutaneous rHuEPO can stimulate erythroid marrow activity in cancer anaemia, even in patients with advanced disease, and marrow response can be adequately monitored by serum TfR. Functional iron deficiency as a cause of nonresponse to rHuEPO is frequent in these patients and may require parenteral iron administration. Although erythropoietin can improve the anaemia of cancer, the decision to treat should be individualised for each patient, looking more at the quality of life and cost-effectiveness than at cosmetic increases in the haemoglobin level.

Aged↗