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The role of magnesium is primarily that of a cofactor in intracellular biochemical reactions, therefore, the concentration of intracellular ionized magnesium is much more physiologically relevant. The determination of the ionized magnesium (iMge) in erythrocytes by ion-selective electrode for routine clinical measurements was first time investigated. Intracellular and extracellular magnesium concentration in critically ill postoperative patients and in dialyzed patients was compared with healthy individuals. Of the investigated parameters, iMge seems to be the best magnesium parameter to observe hypo- or hypermagnesemia for both groups of patients. The correlation that was found between extracellular and intracellular magnesium concentrations can be also used to evaluate the magnesium status.
Biological knowledge is expanding rapidly, delving deep into nature’s mechanisms. However, the essence of life as a molecular process still remains unclear. Organized and independently operating biological systems are commonly thought to be living. Unfortunately, these characteristics are too general and altogether insufficient to accurately delimit the boundaries of life. The problem of the relation of many primitive biological entities to the living world is still open. The properties of self-dependent biological systems clearly derive from their highly organized automatic nature. The comparative analysis of genomes of primitive biological organisms seems to be the most promising approach, which may eventually lead to the understanding of life at the molecular level and its definition. The erythrocyte appears to be of particular interest as a model of a living system that is at a boundary. Its biological origin, automatically controlled metabolism, and programmed death sharply defined in time qualify it as the living structure, even though it is completely deprived of a genetic apparatus. However, its membership among living systems seems to be well-founded. Protein aggregation is one of the common characteristics of aging. It is a consequence of abnormalities of protein structure induced by destructive actions but also by abnormalities of synthesis. Aggregation of membrane proteins probably affects the activity of certain enzymes or transport proteins, which are important as energy providers for aging erythrocytes. After the erythrocyte has passed through the vascular system a given number of times, it is not able to undergo a certain set of indispensable metabolic rearrangements. A living thing is then a form of animated nature which has the features of independence as a result of automation and possesses its own compatible with nature program of action which is time-limited beforehand.
Data from 75 bird species weighing between 6 g and > 16 kg confirmed a supposition that the amount of haemoglobin per unit surface area of erythrocyte was not dependent on body mass. It showed a constancy across the range reflecting adjustment of the total surface area of erythrocytes in relation to blood haemoglobin concentration. This conclusion is based on an inverse correlation between the numbers and sizes of red blood cells.
Zbadano zależności wartości wskaźników czerwonokrwinkowych od masy ciała ptaków. Do analizy tej włączono dane własne, uzyskane we wcześniejszych badaniach (Kostelecka-Myrcha et al. 1993) i dostępne dane literaturowe. Ogółem zebrano informacje dla 75 gatunków ptaków, o masie ciała od 6 g do ponad 16 kg. Poszczególne zależności scharakteryzowano za pomocą współczynników korelacji i regresji krzywoliniowych. Stwierdzono, że koncentracja hemoglobiny (Hb, Fig. 1) i liczba erytrocytów w 1 mm³ krwi (Fig. 2) zmniejszają się statystycznie istotnie ze wzrostem masy ciała ptaków, podczas gdy wielkość tych krwinek wzrasta (Fig. 3). Bardzo intensywne zmniejszanie się liczby erytrocytów w jednostce objętości krwi powoduje statystycznie istotne zmniejszanie się wartości hematokrytu (Fig. 4) i sumarycznej powierzchni erytrocytów (TSAE, Fig. 5). Zmiany wielkości tej powierzchni przebiegają wprost proporcjonalnie do zmian koncentracji Hb i dlatego stosunek Hb/TSAE nie zależy od masy ciała ptaków (Fig. 6). Jego średnia wartość wynosi 0.52 ± 0.09 pg μm⁻². Nie różni się ona statystycznie istotnie od wcześniej otrzymanej średniej dla 564 osobników różnych gatunków ptaków, przebadanych w zależności od wieku piskląt, sezonu roku i masy ciała, w wąskim zakresie jej zmienności — od 6 g do 167 g (Kostelecka-Myrcha 1997). Przedstawiona analiza potwierdza więc przypuszczenie z 1997 roku (ibidem), że ilość hemoglobiny przypadająca na jednostkę powierzchni erytrocytów (Hb/TSAE) jest u ptaków stała, i że stałość ta jest wynikiem dostosowywania się wielkości TSAE do koncentracji Hb. U podstaw tego ważnego mechanizmu, zapewniającego zawsze pełne wysycenie hemoglobiny tlenem, leży ujemna korelacja między liczbą a wielkością erytrocytów.
The shapes of red blood cells with fluid interior depend on the properties of their membranes. The red blood cell membrane is composed of a bilayer, containing integral proteins, and the underlying membrane skeleton, which are attached to each other through different specific and nonspecific linkages. A short account is given of theories of shape formation based on the description of the membrane as a single- or multi-layered elastic continuum. Existing experimental evidence is then outlined which indicates that some relevant shape determining factors reside in the specific properties of different red blood cell integral and skeletal proteins. In this context a theoretical approach is introduced, based on the chemical equilibria established by the interacting skeletal and integral proteins. A simple prototype model is analyzed, taking into consideration that the binding between integral membrane proteins and the skeleton depends on membrane curvature. The essential parameters of the model are the gross value of the corresponding interaction energy and the coefficient measuring the dependence of this energy on membrane curvature. The effects of these parameters on RBC shapes and on the lateral mobility of integral membrane proteins are demonstrated.
The active transport of oxidized glutathione and glutathione S-conjugates has been demonstrated for the first time in erythrocytes and this cell remained the main subject of research on the "glutathione S-conjugate pump" for years. Further studies identified the "glutathione S-conjugate pump" as multidrug resistance-associated protein (MRP). Even though cells overexpressing MRP and isolated MRP provide useful information on MRP structure and function, the erythrocyte remains an interesting model cell for studies of MRP1 in its natural environment, including the substrate specificity and ATPase activity of the protein.
Introduction: An important parameter characterizing the ability of erythrocytes to deform depending on the blood flow conditions is the Elongation Index (EI), and it is a parameter defined by the shape of the erythrocyte obtained as a diffraction pattern of erythrocytes at different values of shear stresses. Material and methods: EI measurements at different shear stress were performed by Laser-assisted Optical Rotational Cell Analyzer (LORRCA) for erythrocytes derived from Tissue Bank in Katowice. Measurements were performed immediately after receiving them from Tissue Bank and after 2, 9, and 28 days of storage of samples at the temperature of 4°C in solution with the anticoagulant. Results: An increase in the erythrocytes Elongation Index in the first 9 days of storing samples at low temperatures was observed in the entire range of applied shear stresses. This indicates an increase in the elasticity of erythrocytes during short-term storage at 4°C. In turn, on the 28th day of erythrocyte storage, a significant decrease in the Elongation Index for shear stresses greater than 1 Pa was observed, which indicates the stiffening of the erythrocyte membrane structure, reducing their elasticity. The relative decrease in the Elongation Index of erythrocytes stored for 28 days compared to erythrocytes measured at the beginning was similar and slightly greater than 30% for shear stresses greater than 3 Pa. For shear stresses lower than 3 Pa, the relative change in elongation index was smaller than for shear stresses greater than 3 Pa and increased with the increase in shear stress. Conclusions: The elongation index of erythrocytes stored in the anticoagulant solution at 4°C, initially increases in the entire range of applied shear stresses in the first few days from the moment of blood collection and preparation at the Tissue Bank, and then decreases, but on the ninth day of storage the elongation index is still higher than for blood immediately after collection.
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