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Parvovirus
Published in Vincenzo Berghella, Maternal-Fetal Evidence Based Guidelines, 2022
Parvovirus B19 is mainly transmitted by respiratory droplets. The incubation period for erythema infectiosum is 13–18 days, and infectivity is greatest 7–10 days before the onset of symptoms. The major target cells for parvovirus B19 are erythroid progenitors bearing the main cellular parvovirus B19 receptor P blood group antigen globoside on their surface (Figure 51.1). The virus is believed to cause arrest of maturation of red blood cell (RBC) precursors at the late normoblast stage and causes a decrease in the number of platelets. The virus causes infection and lysis of erythroid progenitor cells by apoptosis, leading to hemolysis and transient aplastic crisis. Subsequent fetal anemia is thought to be responsible for the development of skin edema and effusions. Hepatitis, placentitis, and myocarditis leading to heart failure may contribute to the development of fetal hydrops [2, 4, 5]. Parvovirus B19 has been demonstrated to carry an apoptosis-inducing factor and to induce cell-cycle arrest. Cells in the S-phase of DNA mitosis are particularly vulnerable to parvo-virus B19, and the fetus is at risk because of the vast number of cells in active mitosis, shorter half-life of RBCs, and an immature immune system.
Red Blood Cells and Haemoglobin
Published in Lara Wijayasiri, Kate McCombe, Paul Hatton, David Bogod, The Primary FRCA Structured Oral Examination Study Guide 1, 2017
Lara Wijayasiri, Kate McCombe, Paul Hatton, David Bogod
Proerythroblast → Prorubricyte → Rubricyte → Normoblast → Reticulocyte (nucleus ejected by this phase, allowing the centre of the cell to indent giving the cell its biconcave shape – these now squeeze out of the bone marrow and into the circulation) → Erythroblast
Bone Marrow
Published in Wojciech Gorczyca, Atlas of Differential Diagnosis in Neoplastic Hematopathology, 2014
The erythroid lineage matures from stem cells to red cells (which carry oxygen to the peripheral tissues) through proerythroblast (pronormoblast), basophilic normoblast (basophilic erythroblast), polychromatic normoblast (early polychromatic erythroblast), orthochromatic normoblast (late polychromatic erythroblasts), and reticulocyte. Pronormoblasts are large cells with a prominent nucleolus, a fine chromatin pattern, and a deeply basophilic cytoplasm, which may be vacuolated. Basophilic normoblast is smaller, has more basophilic cytoplasm and coarse (granular) chromatin, and lacks nucleolus. Polychromatic normoblast is characterized by chromatin clumps and polychromatic cytoplasm. Orthochromatic normoblast is smaller and has an eccentric nucleus with a condensed chromatin that becomes pyknotic at later stages of maturation.
Luspatercept for β-thalassemia: beyond red blood cell transfusions
Published in Expert Opinion on Biological Therapy, 2021
Ali T. Taher, Maria Domenica Cappellini
β-thalassemia is a hereditary hemoglobinopathy caused by over 400 identified mutations (as of 1 July 2021) of the β-globin gene (HBB) or promoter region that reduce or prevent the expression of the β-globin subunit of hemoglobin (Hb) in erythroid precursors (Figure 1) [1,2]. The resultant defects in Hb production are associated with premature cell death via apoptosis, and a reduction in the rates of late-stage maturation and differentiation of red blood cell (RBC) precursors; ineffective erythropoiesis, anemia, hypoxia, and iron homeostasis dysregulation are the consequences [3]. Ineffective erythropoiesis is a hallmark of β-thalassemia and is characterized by abnormalities in differentiation or maturation of erythroid precursors and apoptosis of erythroblasts, leading to a lower than expected number of mature erythroblasts despite increased proliferation of progenitors [4]. Ineffective erythropoiesis in β-thalassemia may be due to a number of related mechanisms, such as increased apoptosis of erythroid progenitors (possibly at the polychromatic normoblast stage), decreased differentiation of erythroid progenitors (leading to an increased proportion of immature progenitors and a lower proportion of mature cells), and oxidative stress (due to the imbalance in α-globin and β-globin chains and the resultant aggregation and precipitation of free α-globin chains in erythroid progenitors).
Modulation of hepcidin expression by normal control and beta0-thalassemia/Hb E erythroblasts
Published in Hematology, 2018
Janejira Jaratsittisin, Wannapa Sornjai, Saovaros Svasti, Suthat Fucharoen, Sittiruk Roytrakul, Duncan R. Smith
Beta0-thalassemia/Hb E is a compound-inherited disorder, deriving from the co-inheritance of a mutation in one allele of the beta-globin gene and the structural hemoglobin HbE variant in the second allele [17]. Even after allowing for additional modifying factors such as co-inheritance of alpha-hemoglobinopathies, presentation of this disease is remarkably varied, ranging from mild anemia to a severe, transfusion-dependent anemia [18]. The unbalanced production of alpha-globin chains leads to the death of the developing erythroblast at the polychromatic normoblast stage in a process termed ineffective erythropoiesis [19]. The resultant anemia leads to expansion of the erythroid mass, and it has been proposed, based on studies in mice, that the subsequently increased secretion of erythroferrone results in the decreased hepcidin expression observed in beta-thalassemia patients [16,20].
β-catenin and PPAR-γ levels in bone marrow of myeloproliferative neoplasm: an immunohistochemical and ultrastructural study
Published in Ultrastructural Pathology, 2018
Tijana Subotički, Olivera Mitrović Ajtić, Mileva Mićić, Tamara Kravić Stevović, Dragoslava Đikić, Miloš Diklić, Danijela Leković, Mirjana Gotić, Vladan P. Čokić
Distinguishing three MPN subtypes in the early phase is important, because of a different risk of thromboembolic complications for PV and the inferior survival rate of PMF compared to ET patients.29 Our results show that Ki67 and PPARγ have the same trend of expression in MPNs, bearing in mind that proliferative index has been significantly increased in PMF and PV patients compared to ET group of patients. In contrast to those two markers, β-catenin has opposite pattern of expression in correlation with Ki67 and PPARγ. According to those statement we could conclude that patients with high level of Ki67 and PPARγ expression has more progressive form of disease (PMF) in comparison to those who has high level of β-catenin expression (PV). Electron microscopy showed that bone marrow of PV patients can be recognized by numerous mature erythrocytes, normoblast, myeloid cells and platelets. Also, megakaryocytes are pleomorphic and vary in size, but they are without maturing defects. Characteristic for ET patients are the large, hyperlobulated and mature-appearing megakaryocytes clustered loosely together. In contrast, megakaryocytes in bone marrow of PMF patients show abnormal maturation and have hyperchromatic and irregularly folded bulky nuclei which are densely clustered. Furthermore, reticulin and collagen fibrosis and often osteosclerosis are present in fibrotic PMF. Low grades of reticulin fibrosis are sometimes also found in the bone marrow of ET and PV patients.30 PMF has the worst prognosis among the MPNs.31 The disease can start as PMF or as the burnt out phase of PV (post-PV MF) or ET (post-ET MF).32 In all MPNs, megakaryocytes proliferate, acquire multilobulated nuclei and exhibit clustering in the bone marrow.33 It has been shown that mice with a megakaryocyte deficiency of Gata 1have elevated number of immature megakaryocytes and severe bone marrow fibrosis.34 Megakaryocytes from PMF patients secrete increased levels of the fibrotic cytokine TGF-β.35 However, the extent to which megakaryocytes are required for myelofibrosis and whether targeting the megakaryocyte lineage is sufficient to prevent disease has not been shown.