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Dopamine in the Immune and Hematopoietic Systems
Published in Nira Ben-Jonathan, Dopamine, 2020
Human erythrocytes have a structure of a biconcave disk with a diameter of 7 µm. They lack a nucleus and most organelles, and their average life in the circulation is 120 days. The cytoplasm of erythrocytes is rich in hemoglobin, an iron-containing, 68-kDa biomolecule that binds oxygen via its heme subunit and gives rise to the red color of the cells and blood. The cell membrane of erythrocyte is composed of a mesh of fibrous proteins that confer the cells with great flexibility and the ability to deform while traversing the narrow capillary network of the circulatory system. The erythrocyte membrane contains ion pumps that maintain high levels of intracellular potassium and low levels of calcium. The main function of erythrocytes is to carry oxygen from the lungs to the tissues and carbon dioxide, as a waste product, away from the tissues and back to the lungs.
Incredible journeys
Published in Brendan Curran, A Terrible Beauty is Born, 2020
The normal shape of a red blood cell, one that picks up oxygen in the lungs and transports it to the body cells, is that of a biconcave disc (Figure 2.5 (a)). This shape is necessary because it allows many to pack closely together without clogging the very fine blood vessels (called capillaries) that deliver the blood to the organs all over the body. There is, however, a condition called sickle cell anaemia in which the red cells have a fundamentally different shape (Figure 2.5 (b)); this minor alteration in just one type of body cell has a dramatic knock-on effect on the entire organism. In this disease, for that is what it is, the cells have a crescent or sickle shape which results in their becoming jammed in fine blood vessels and in clumping together. This causes blockage of the blood supply to all the major organs with consequent damage to lungs, kidneys, heart, intestines and brain. The body recognises that they are the wrong shape and traps them in the spleen to destroy them. Unfortunately this further aggravates matters because the person then develops anaemia (or lack of red blood cells), putting even more pressure on the already compromised heart. If left untreated, a person suffering from this condition will die at a very young age. Even with regular blood transfusions, the patient’s quality of life is severely constrained.
The HbS Containing Cell
Published in Ronald L. Nagel, Genetically Abnormal Red Cells, 2019
Ronald L. Nagel, Mary E. Fabry
The sickling of SS red cells is due to the intracellular polymerization of HbS into bundles or fascicles of fibers induced by the deoxygenation of the HbS molecule. It has been known for a long time126,127 that this change in phase of the hemoglobin molecule can be accompanied by varied shape changes detectable by the microscopic observation of the cell. The cell might appear no longer as a biconcave disc but as a bumpy, flat spheroid (called “deformed” by most authors) or it might appear as a holly leaf with digitations in all directions. It can have two main digitations as in the classical but infrequent “sickle” shape. The cell might contain polymer and exhibit no morphological anomaly. And finally, it might have morphological changes and no polymer.128 Some of these facts have been “rediscovered” often.129
Dapsone-induced methemoglobinemia and hemolysis in a woman without G6PD deficiency presenting with idiopathic urticaria
Published in Hematology, 2022
Yang Hu, Mimansa Geere, Maham Awan, Andrew D. Leavitt, Laura E. Brown, Hadley J. Pearson, Jocelyn S. Gandelman, Scott C. Kogan
The ‘bite cell’ is an aberrant feature of mature red blood cells seen on peripheral smear characterized by removal of one or more portions of the biconcave disc rim of red blood cells by splenic macrophages at sites where hemoglobin has been abnormally deposited [1]. Occasionally, ‘blister cells’, which have a large vacuole along the periphery, may also form alongside ‘bite cells.’ Oxidative injury of red blood cells can result in hemoglobin sulfhydryl group oxidation, which can precipitate the formation of these abnormal red blood cell features. They are most commonly associated with hemolysis and methemoglobinemia in patients with G6PD deficiency exposed to triggers such as medications including dapsone [14,15]. Dapsone is a sulfone antibiotic used as first line therapy for leprosy and second line therapy for Pneumocystis pneumonia [16]. It can also be used as a second line therapy for chronic spontaneous urticaria [2,17]. Dapsone is converted to the metabolite hydroxylamine, which can accumulate in red blood cells and generate free radicals that deplete glutathione stores, leading to oxidative damage of the red blood cell membrane [18]. G6PD is a key enzyme that participates in restoring glutathione. In the rare case of dapsone overdose, hydroxylamine can accumulate to excess levels to overwhelm the protective effect of glutathione and cause oxidative damage to red blood cells even in the presence of normal G6PD levels [11].
Hepatotoxic effect of lead and hepatoprotective effect of Hydrilla verticillata on hepatic transcriptional and physiological response in edible fish Labeo rohita
Published in Drug and Chemical Toxicology, 2022
Pandi Prabha S., Johanna Rajkumar, Karthik C.
Lead intoxication caused cell damage but feeding with supplementary diet with hydrilla normal RBC structure was retained. In control fish group, RBC appeared as spheres or biconcave disks. RBCs are more susceptible to lead poisoning. Lead toxicity caused noticeable disruption of RBC which leads to hemolysis and cause anemia even at very low levels of exposure. The cell damage may be due to its high potential in changing osmotic fragility, interaction of lead with membrane protein, an increase of oxidative stress or may be due to interaction with some essential trace metals in the blood. Mrugesh et al. (2011) reported that lead can affect the red blood cells by oxidative stress either directly or indirectly that initiates lipid peroxidation in RBC. Further, it also altered lipid metabolism, enhances lipid peroxidation and decreases cell membrane fluidity. Vetrivel (2015) reported that lead may accumulate in cell membranes and disturb the membrane structure of RBC.
Current perspectives of sickle cell disease in Nigeria: changing the narratives
Published in Expert Review of Hematology, 2019
Oyesola O. Ojewunmi, Titilope A. Adeyemo, Oluseyi C. Ayinde, Bamidele Iwalokun, Adekunle Adekile
Under low oxygen tension, HbS chains form a hydrophobic contact between valine on one chain and other amino acids such as alanine, phenylalanine, and leucine on the other chain [4,5]. This crystallization gives rise to a polymer nucleus, which grows and fills the red blood cell, unsettling its architecture and elasticity and promoting cellular dehydration, with physical and oxidative cellular stress (Stuart and Nagel, 2004). HbS tends to aggregate into rodlike polymers, alters the normal, biconcave disc shape resulting in the deformed sickle shape and rigidity of red blood cells (RBCs) characteristic of this condition [6]. The polymerization of deoxygenated HbS is the primary indispensable event in the molecular pathogenesis of sickle-cell disease. It is dependent on intraerythrocytic HbS concentration, extent and duration of cell deoxygenation, pH, and the intracellular concentration of HbF [7].