PubMed · 1102195
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
L Szur, S M Lewis. 1975. Iron kinetics.. https://pubmed.ncbi.nlm.nih.gov/1102195/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Hemolytic and subhemolytic blood damage by mechanical heart valve prostheses have been observed in both clinical and in vitro investigations. A direct comparison between these studies is not possible. Nevertheless the transfer of some in vitro results to the behaviour of the valve in situ may be performed considering the similarity principle. This requires the use of dimensionless similarity numbers such as the plasma's hemoglobin concentration (PHb) or others, instead of dimensioned parameters. To evaluate the in vitro hemolysis of valve prosthesis a test chamber filled with human banked blood was used. An artificial ventricle ensuring an oscillatory flow through the valve was also used. The rise of PHb was evaluated in terms of a similarity number, called the lysis number. This number describes the probability of destroying a single red blood cell participating once in the hemolytic process under consideration. The lysis number, a Björk-Shiley valve (TAD 29), was found to be in the order of 2 x 10(-4). From this, the survival time of erythrocytes in patients with an artificial heart valve was estimated. It was found to be in the order of 20 d of T50 Cr in agreement with clinical results.
Explore the source record for details and available documents.
1. Exercise-induced haemolysis has been implicated in the sub-optimal iron status of endurance-trained athletes. Accordingly, erythrocyte survival studies using 51Cr were performed on male and female distance runners (n = 20) and sedentary control subjects (n = 10) in order to determine whether the rate of erythrocyte destruction was altered as a consequence of repetitive exercise training. 2. The chromium half-disappearance time of the male (25.4 +/- 3.6 days, mean +/- SD) but not the female (28.3 +/- 4.6 days) athletes was significantly lower than that of the male (33.1 +/- 4.5 days) and female (32.3 +/- 2.6 days) control subjects (P less than 0.01). The mean erythrocyte lifespan of the male and female distance runners (67.2 +/- 22.2 and 72.4 +/- 26.0 days, respectively) was significantly shorter than that of the non-exercising male and female subjects (113.4 +/- 31.0 and 114.1 +/- 29.0 days, respectively) (P less than 0.01). 3. There was no correlation between the mean erythrocyte lifespan and the haemoglobin concentration, serum ferritin levels, body mass, weekly training distance, number of years running or daily protein intake. The mean cell volume and reticulocyte count measured in the same athletes before and after completing a standard 42 km marathon race were within the normal range, whereas the plasma haemoglobin levels were elevated (77.0 +/- 50.5 mg/l) and the serum haptoglobin levels were decreased (0.89 +/- 0.4 g/l) at rest, with a further significant decrease after running (0.69 +/- 0.4 g/l) in the latter measurement (P less than 0.05). 4. It is concluded that the demonstrated increase in erythrocyte turnover may be sufficient to precipitate an iron deficiency in endurance athletes when dietary intake or absorption does not meet the accelerated erythropoietic demands.