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Cellular Components of Blood
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Hb contains 65%–70% of the total body iron, with myoglobin containing 4%–5%. Iron is also associated with cellular respiration through the action of iron-containing enzymes such as cytochromes, catalase and peroxidase. Iron is transported in plasma by transferrin, a β1-globulin that binds two atoms of ferric iron per molecule. The main source of iron carried by transferrin is from the reticuloendothelial cells that destroy ageing red cells. Some iron is also stored in the reticuloendothelial cells as haemosiderin and ferritin. Ferritin is a water-soluble protein–iron complex consisting of an outer protein shell, called apoferritin, and an inner core of iron–phosphate–hydroxide complex.
The Use of Tracers in Transport Studies
Published in Joan Gil, Models of Lung Disease, 2020
Maya Simionescu, Nicolae Ghinea
An anionic protein in its native form, horse spleen ferritin consists of a spherical apoferritin shell (~ 3 nm thick) with a diameter of — 13 nm (Fischbach et al., 1969) and a core of ferric hydroxyphosphate micelles that constitute up to 40% of its dry weight (Crichton, 1971). The prevalence of acidic residues impart to ferritin its pI of 4.5. By chemical modifications of protein functional groups (i.e., amino and carboxyl groups), anionic and cationic ferritin derivatives have been obtained (Danon et al., 1972; Rennke et al., 1975; Kanwar and Farquhar, 1979; Ghinea and Hasu, 1986). Ferritin (and its derivatives) has an Mr of ~ 960 kD, to which the apoferritin shell (composed of 24 subunits) contributes an Mr of ~ 445 kD (Panitz and Ghiglia, 1982). Ferritin is electron dense by virtue of its 5.5 nm iron core (Fig. 1a). The whole molecule (the iron core and the apoferritin shell) can become visible upon staining of sections with metallic bismuth, which binds to and stains the apoferritin shell, thus exposing the effective diameter of the molecule (Ainsworth and Karnovsky 1972). In addition to its value for its intrinsic electron opaqueness, ferritin was used successfully as tracer because of its relatively homogeneous size. When cadmium-free it is well tolerated by animals and may be coupled to active molecules to give conjugates that maintain appreciable biological activity (i.e., low-density lipoprotein-ferritin [Anderson et al., 1976], histamine-ferritin [Heltianu et al., 1983]).
The Hematologic System and its Disorders
Published in Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss, Understanding Medical Terms, 2020
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss
The life of a red blood cell is about 120 days, during which time some metabolic processes continue to occur. Some of the enzymes in the cytoplasm release energy to maintain cell integrity, but eventually the erythrocyte becomes fragile and breaks as it passes through a capillary. The fragments of the cell structure are engulfed by reticuloendothelial cells lining the capillaries of some organs, primarily the liver and spleen. These digest the fragments and release the dissolved components into the circulation. The hemoglobin molecules soon diffuse through the capillary walls and are engulfed by tissue reticuloendothelial cells. Digestion of hemoglobin releases the breakdown products iron and bilirubin. The iron combines with a globulin; to form transferrin, the form in which it is carried throughout the body for storage and reuse. In the liver, iron combines with apoferritin to form ferritin, conserving the iron for future use. The bilirubin is excreted through the liver into the bile.
Assessment of serum ferritin as a biomarker in COVID-19: bystander or participant? Insights by comparison with other infectious and non-infectious diseases
Published in Biomarkers, 2020
Kai Kappert, Amir Jahić, Rudolf Tauber
The pathophysiological background of hyperferritinemia in SARS-CoV-2 is not fully understood and remains hitherto elusive. Since hyperferritinemia in COVID-19 patients is most likely due to the observed cytokine storm and sHLH, forthcoming studies will have to address the question if macrophage activation and secretion via nonclassical pathways are responsible for the increased generation of serum ferritin (Cohen et al.2010). Moreover, it remains to be clarified if serum ferritin has protective effects by trapping of iron thus limiting the damage by free radicals generated in the presence of Fe(II) (Kernan and Carcillo 2017). Future studies may address the question if monitoring of total serum iron, serum ferritin and regulators of iron homeostasis such as hepcidin may give a hint if the elevation of serum ferritin may cause sequestration of iron into macrophages or hepatocytes. This could be of particular interest since cell culture experiments have shown that iron-loaded ferritin is more cytotoxic, while apoferritin appears to be protective (Kurz et al.2011).
Thrombocytopenia in congenital heart disease patients
Published in Platelets, 2015
Efrén Martínez-Quintana, Fayna Rodríguez-González
After an overnight fast of at least 10 hours, blood samples were drawn for the measurements of analytical data. All blood samples were processed immediately after sampling. Complete blood counts were performed on a Coulter LH 750 (Beckman Coulter, Fullerton, CA) analyzer to determine hemoglobin (normal range: 12–16 g/dl), hematocrit (normal range: 36–46%), mean corpuscular volume (MVC) (normal range: 80–100 fl), mean corpuscular hemoglobin (MCH) (normal range: 26–34 pg), leucocytes (normal range: 4.500–11.000 /μl), platelet count (normal range: 150–400 × 103/μl), and MPV (normal range: 7.4–11.1 fl). Serum apoferritin, ferritin that is not combined with iron, (normal range: 20–186 ng/ml) was determined using a Beckman Coulter UniCel DxI 800 system (Beckman Coulter, Fullerton, CA). C reactive protein (CRP) (normal range: 0.0–0.50 mg/dl), serum creatinine (normal range: 0.6–1.5 mg/dl), and 24-hour microalbuminuria (normal range: 0.0–3.0 mg/dl) were determined by spectrophotometric methods using an Olympus AU 2700 (Olympus Diagnostic, Hamburg, Germany). Hemoglobin oxygen saturation was assessed by pulse oximeter (Pulsox 300i, Konica Minolta Sensing Inc. Osaka, Japan).
Apoferritin: a potential nanocarrier for cancer imaging and drug delivery
Published in Expert Review of Anticancer Therapy, 2021
Hanitrarimalala Veroniaina, Xiuhua Pan, Zhenghong Wu, Xiaole Qi
Fan et al. demonstrated that magnetoferritin nanoparticles (M-HFn) can be used to target and visualize tumor tissues without the use of any targeting ligands or contrast agents [45]. Iron oxide nanoparticles are encapsulated within the recombinant human H-chain apoferritin. The iron oxide core catalyzes the oxidation of peroxidase substrates in the presence of hydrogen peroxide to produce a color reaction that is used to visualize tumor tissues. They examined 474 clinical specimens from patients with nine types of cancer and verified that these nanoparticles can distinguish cancerous cells from normal cells with a sensitivity of 98% and specificity of 95%.