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Biomedical subjects

G Fillet

Publications and source records attributed to G Fillet.

At least 109 records · Page 6Linked to original sources
PubMed1992

Erythropoiesis in multiple myeloma: defective red cell production due to inappropriate erythropoietin production.

We investigated the pathophysiology of erythropoiesis in 62 patients with multiple myeloma and examined whether it would establish a rational basis for the treatment of their anaemia with recombinant human erythropoietin. Erythropoietin (Epo) production was evaluated by serum levels and erythropoiesis was quantitated by serum transferrin receptor (TfR) levels, both assessed relative to the degree of anaemia. Instead of the expected stimulation of erythropoiesis in response to anaemia, haematocrit correlated positively with marrow erythropoietic activity, indicating that the mechanism of anaemia was primarily defective red cell production. Erythropoiesis decreased and anaemia worsened significantly with advancing clinical stage. 25% of the patients had inadequate Epo production and this proportion increased to 50% in stage 3. Inappropriate Epo production was seen in 60% of patients with renal impairment but was also observed in a number of patients with normal renal function. Erythropoiesis correlated strongly with the adequacy of Epo production, particularly in advanced disease. We conclude that most myeloma patients have defective red cell production even in the absence of massive marrow infiltration and that inappropriate Epo production contributes to their anaemia.

Adult↗
PubMed1991

Blunted erythropoietin production and decreased erythropoiesis in early pregnancy.

After decreasing in the first trimester of pregnancy, the total red blood cell mass increases in the second and third trimesters to peak at term at about 120% to 125% of nonpregnant values, but how this is brought about by changes in the rate of erythropoiesis is not known. We evaluated erythropoiesis by measuring serum transferrin receptor (TfR) levels in 406 women during normal pregnancy (N = 317), at delivery (N = 63), or in the early postpartum (N = 27). Despite the presence of the placenta and the frequent occurrence of iron deficiency, TfR levels remained low in the first two trimesters and increased in the third trimester and at delivery. To explain why erythropoiesic activity was relatively low in early pregnancy, we also measured serum immunoreactive erythropoietin (Epo) in relation to the degree of anemia. There was a very strong correlation between serum TfR and Epo levels in the entire group (r = .59, P less than .0001) as well as in each period of pregnancy. Epo levels remained low for the degree of anemia and did not correlate with hematocrit in the first two trimesters, but recovered afterwards. In the early postpartum, Epo production and erythropoiesis were normal. We conclude that: (1) erythropoiesis is decreased in the first part of pregnancy but increases afterwards; and (2) blunted Epo production in early pregnancy could be responsible for that observation.

Adolescent↗
PubMed1991

Circulating erythropoietin levels after bone marrow transplantation: inappropriate response to anemia in allogeneic transplants.

We studied 24 recipients of autologous bone marrow transplantation (ABMT) or allogeneic BMT (BMT) to determine whether impaired erythropoietin (Epo) response to anemia could delay full erythropoietic recovery. Observed Epo levels were compared with predicted levels based on the relationship between Epo and hematocrit in 125 control subjects. Circulating Epo levels were normal during conditioning and the early posttransplant period. Between days 21 and 180, Epo levels remained normal in ABMT patients but were inappropriately low for the degree of anemia in BMT patients. Median time to full erythropoietic engraftment was longer in BMT than in ABMT recipients. Circulating Epo returned to appropriate levels after day 180, except in patients with active cytomegalovirus infection. We conclude that impaired Epo response to anemia can contribute to delayed erythropoietic recovery after allogenic BMT. Renal toxicity of ciclosporin, interaction between host and donor marrow, and cytomegalovirus infection might play a role. This study could support the use of recombinant human Epo to accelerate erythropoietic engraftment after BMT.

Adolescent↗
PubMed1990

Serum immunoreactive erythropoietin during pregnancy and in the early postpartum.

We studied 209 women during normal pregnancy, at delivery, or in the early postpartum, to determine whether erythropoietin (EPO) response was appropriate for the degree of anaemia. Serum immunoreactive EPO was measured in 74 nonpregnant women, including 33 normal subjects (16.4 +/- 4.1 mU/ml) and 41 women with hypoplastic, haemolytic, dyserythropoietic, or iron-deficient anaemia. An inverse linear relationship (R = -0.88, P less than 0.0001) between log(EPO) and Hct was observed. Predicted EPO values were derived for each Hct and an O/P ratio of observed/predicted log(EPO) was calculated for each sample (1.00 +/- 0.10, range 0.80-1.20). Serum EPO levels (mU/ml) were significantly higher during pregnancy (30 +/- 16, n = 142), at delivery (31 +/- 16, n = 41), and on day 7 postpartum (37 +/- 35, n = 26) than in normal women (P less than 0.001). EPO levels increased steadily from 18 +/- 6 mU/ml in the first, to 26 +/- 14 mU/ml in the second, and to 35 +/- 18 mU/ml in the third trimester (P less than 0.0001). The O/P ratio was normal on day 7 postpartum (1.01 +/- 0.16), at delivery (1.03 +/- 0.16), and in the third trimester (0.96 +/- 0.15), but was significantly reduced in the first two trimesters (0.88 +/- 0.15, P less than 0.001). A significant negative correlation between log(EPO) and Hct was lacking in the first two trimesters, was present but with a reduced slope during the third trimester and at delivery, and was normal postpartum. We conclude that EPO response to anaemia is impaired in early pregnancy, recovers in late pregnancy, and normalizes rapidly in the postpartum.

Adolescent↗
PubMed1989

Model of reticuloendothelial iron metabolism in humans: abnormal behavior in idiopathic hemochromatosis and in inflammation.

Iron transport in the reticuloendothelial (RE) system plays a central role in iron metabolism, but its regulation has not been characterized physiologically in vivo in humans. In particular, why serum iron is elevated and RE cells are much less iron-loaded than parenchymal cells in idiopathic hemochromatosis is not known. The processing of erythrocyte iron by the RE system was studied after intravenous (IV) injection of 59Fe heat-damaged RBCs (HDRBCs) and 55Fe transferrin in normal subjects and in patients with iron deficiency, idiopathic hemochromatosis, inflammation, marrow aplasia, or hyperplastic erythropoiesis. Early release of 59Fe by the RE system was calculated from the plasma iron turnover and the 59Fe plasma reappearance curve. Late release was calculated from the ratio of 59Fe/55Fe RBC utilization in 2 weeks. The partitioning of iron between the early (release from heme catabolism) and late (release from RE stores) phases depended on the size of RE iron stores, as illustrated by the inverse relationship observed between early release and plasma ferritin (P less than .001). There was a strong correlation between early release and the rate of change of serum iron levels during the first three hours in normal subjects (r = .85, P less than .001). Inflammation produced a blockade of the early release phase, whereas in idiopathic hemochromatosis early release was considerably increased as compared with subjects with similar iron stores. Based on these results, we describe a model of RE iron metabolism in humans. We conclude that the RE system appears to determine the diurnal fluctuations in serum iron levels through variations in the immediate output of heme iron. In idiopathic hemochromatosis, a defect of the RE cell in withholding iron freed from hemoglobin could be responsible for the high serum iron levels and low RE iron stores.

Erythrocytes, Abnormal↗
PubMed1989

Ferrokinetic study of splenic erythropoiesis: relationships among clinical diagnosis, myelofibrosis, splenomegaly, and extramedullary erythropoiesis.

Splenic erythropoiesis was demonstrated by surface counting of 59Fe in 129 of 1,350 ferrokinetic studies performed over a 15 year period. These 129 studies were carried out in 108 patients, including 40 with chronic myelogenous leukemia (CML), 24 with agnogenic myeloid metaplasia (AMM), 18 with polycythemia vera (PV), six with a myelodysplastic syndrome, five with acute leukemia, three with prostate or breast carcinoma, two each with aplastic anemia or Hodgkin's disease, and one each with idiopathic thrombocythemia, multiple myeloma, chronic renal failure, or treated hypopituitarism. Splenomegaly was present in 83% of the studies and hepatomegaly in 72%. Grade II-III myelofibrosis was demonstrated in 62% of the cases. Hepatic erythropoiesis was present in 77% of the studies (only 38% in PV), and marrow erythropoiesis was undetectable in 33%. Total erythropoiesis was about twice normal (range 0.2 to 8 times normal) but was ineffective to varying degrees in 86% of the studies. Relationships between organomegaly, myelofibrosis, and extramedullary erythropoiesis, as well as differences among clinical disorders, are discussed. Differences observed between CML in chronic or blastic phase suggested that the erythroid cell line was involved in the proliferative process. It is concluded that splenic erythropoiesis 1) is encountered in a variety of clinical conditions; 2) is not necessarily associated with splenomegaly or myelofibrosis, even in the myeloproliferative disorders; 3) is part of a predominantly extramedullary (in the liver as well as in the spleen), expanded, and largely inefficient total erythropoiesis; and 4) can be evaluated in a semiquantitative manner by surface counting.

Erythropoiesis↗
PubMed1989

Relationship of serum selenium levels to tumor activity in acute non-lymphocytic leukemia.

Serum selenium (Se) levels were measured before, during and after high-dose induction chemotherapy in 70 patients with acute non-lymphocytic leukemia (ANLL). Pre-treatment serum Se levels were lower in patients than in controls (0.082 +/- 0.033 micrograms/ml versus 0.097 +/- 0.035 micrograms/ml, P less than 0.01). Pretreatment serum Se correlated inversely with the absolute peripheral blast cell count (R = -0.62, P less than 0.001) and other measurements of the tumor burden. Seven days after the initiation of chemotherapy, serum Se increased significantly in proportion to the initial tumor burden (P less than 0.01). Thereafter, serum Se levels remained essentially normal in patients entering a complete remission while decreasing gradually in failures. In conclusion, these data do not lend support to the hypothesis that a low selenium status enhances the risk of developing ANLL, but indicate that serum Se levels in patients with acute leukemia are mostly dependent on tumor activity.

Female↗
PubMed1989

[Reutilization of iron in the body and regulation of iron reserves. The value of plasma transferrin receptor levels].

A model for reticulo-endothelial iron metabolism is proposed which characterises diseases of the reutilisation of iron in man. In idiopathic hemochromatosis the RE cell is defective in withholding iron freed from senescent red cells and unable to control the plasma iron level. Transferrin receptor can be measured in plasma, where its concentration is proportionnal to the number of cellular receptors. Plasma levels of transferrin receptor serve as a convenient monitor of total erythropoiesis.

Humans↗