51Cr-tagged Red Cells Research Articles

A single measurement with 51Cr-tagged red cells or 125I-labeled human serum albumin in the prediction of fractional and whole blood volumes: an assessment of the limitations

This study investigated variations in the prediction of blood volumes from a single measurement of red cell volume (RCV) with 51Cr or plasma volume (PV) with 125I human serum albumin (HSA). In 111 subjects, fractional and whole blood volumes were estimated from separate direct measurements of RCV and PV. The f ratio (body to venous hematocrit) was also determined. There was a very good correlation between 125I-HSA measured PV (2857 ± 822 ml) and that estimated with 51Cr-tagged red blood cells (2864 ± 747 ml) (r = 0.936, p = 0.000) and also between 51Cr measured RCV (2600 ± 774 ml) and that estimated with 125I-HSA (2589 ± 843 ml) (r = 0.944, p = 0.000). The 95% limits of agreement (mean ± 2SD of differences, relative to the mean of paired data) ranged −0.2% ± 20.3% and 0.4% ± 21.4%, respectively. The 95% prediction intervals of measured from estimated fractional blood volumes spanned ±20.3% and ±19.5%, respectively, relative to the predicted values with regression equations. Proportional degrees of inaccuracy were found in whole blood volume estimations. The f ratio was inconstant and correlated with PV and the body hematocrit. We conclude that blood volumes can be determined reliabily only with direct measurements of RCV and PV. Estimated blood volumes may lead to misconceptions.

Favism: divicine hemotoxicity in the rat.

Favism is an acute hemolytic anemia known to occur in susceptible individuals who ingest fava beans. Susceptibility to favism is conferred by a genetic deficiency in erythrocytic glucose-6-phosphate dehydrogenase (G6PD) activity. Although the fava bean pyrimidine aglycones, divicine and isouramil, have been implicated in the onset of favism in humans, the lack of a well-defined experimental animal model for favism has hampered progress in elucidating the mechanism underlying hemotoxicity. We have examined whether a favic-like response could be provoked in G6PD-normal rats treated with synthetic divicine. Intraperitoneal administration of divicine to rats preloaded with 51Cr-tagged erythrocytes resulted in a severe, dose-dependent decrease in blood radioactivity (TD50 approximately 0.5 mmol/kg) within 24 h. The increased rate of removal of blood radioactivity was accompanied by a rapid decline in reduced glutathione levels in the blood, decreased hematocrits, marked hemoglobinuria, splenic enlargement, and reticulocytosis. In vitro exposure of 51Cr-tagged red cells to divicine before their re-administration to isologous rats also resulted in a sharp, concentration-dependent decrease in erythrocyte survival in vivo (TC50 approximately 1.5 mM), and these divicine-damaged red cells were removed from the circulation by the spleen. These data demonstrate that a favic response can be induced in G6PD-normal rats treated with divicine, and that hemolytic activity can be reproduced in isolated red cells under conditions that will allow a direct examination of the mechanism underlying this hemotoxicity.

Distribution of Flow and Plasma Skimming In Isolated Perfused Gills of Three Teleosts

ABSTRACT Distribution of flow and red cells between the efferent (epibranchial) and venous pathways was examined with an isolated perfused gill adapted to collect the two effluents separately. Gills from two fish species (Ictalurids) with abundant prelamellar arteriovenous anastomoses (AVAs) were compared with those of the trout which contain few AV As. The gills were perfused with Ringer or Ringer containing 51Cr-tagged red cells (blood). In Ringer-perfused gills, efferent outflow decreased as efferent pressure increased. Epinephrine prevented the decrease in efferent flow at elevated efferent pressures. In all species around one-third of the control blood perfusing the gill drained via the venous pathway. At constant efferent pressure epinephrine increased and acetylcholine decreased efferent outflow. These results suggest that tonic adrenergic stimulation is necessary for normal branchial perfusion. The haematocrit of efferent effluent was greater than venous effluent in all species. No consistent effects of epinephrine or acetylcholine on plasma skimming were observed. Comparison of measured microhaematocrit and haematocrit values calculated from 51Cr red cell space suggests that the red cells in the venous effluent are larger than those from the efferent pathway and supports the concept of a nutritive function for the venous pathway.

Regional brain blood flow, blood volume, and haematocrit values in the adult rat.

Measurements of red cell volume, plasma volume, and tissue haematocrit (Hct) were made in 14 brain regions in adult rats using 51Cr-tagged red cells and 125I-labeled human serum albumin. The mean large vessel (systemic artery) Hct was 41.8, total body Hct was 35.3, and of the brain regions, the lowest value (septal nucleus) was 25.91 and the highest (visual cortex) was 32.05. The lowest blood volume was 6.29 microliters g-1 (caudate putamen) and the highest was 14.44 microliters g-1 (inferior colliculus). There was a significant difference between regions in both blood volume and tissue blood Hct. When brain regions were ranked in order of blood volume, this did not coincide with the order for blood flow.

Chronic hemolysis following mitral valve replacement: A comparative study of the Björk-Shiley, composite-seat Starr-Edwards, and frame-mounted aortic homograft valves

Hemolysis was assessed in 86 patients after mitral valve replacement. Twenty-four patients had mitral valve replacement with a Björk-Shiley valve, 32 patients with a Starr-Edwards composite-seat valve, and 30 patients with an irradiated frame-mounted aortic homograft valve. Hemolysis was determined by red cell survival and autologous 51Cr-tagged red cells, LDH, serum haptoglobin, hemosiderinuria, reticulocyte count, red cell fragment count, and hemoglobin estimation. The degree of hemolysis was classified as mild, moderate, or severe. Thirty-five per cent (nine of 24) of the Björk-Shiley group showed mild hemolysis, whereas 85 per cent (28 of 32) of the Starr-Edwards group had evidence of hemolysis-of these, a third were mild and the rest moderate. The homograft series did not show any comparable evidence of hemolysis. Statistical analysis of the parameters of the study comparing homograft with Björk-Shiley valves showed no significant difference except in red cell survival, which showed a highly significant difference (p less than 0.001). Comparing homograft with Starr-Edwards valves, all parameters showed highly significant differences (p less than 0.001).

Avascular necrosis and erythrocytosis in sickle-cell trait.

THE association of bilateral avascular (aseptic) necrosis of the femoral heads with homozygous hemoglobin S (sickle-cell anemia) and probably more often with hemoglobinopathies SC and S-thalassemia has long been appreciate. 1 2 3 Since 1962, four cases of hemoglobin AS (sickle-cell trait) presumably complicated by this orthopedic problem have been report4 5 6 The white patient described below had hemoglobin AS, bilateral avascular necrosis of the femoral heads, and an unexplained absolute erythrocytosis. Methods Routine clinical laboratory and hematologic data obtained by standard technics,7 and total blood volume and red-cell mass were measured by conventional methods using radioiodinated human serum albumin and 51Cr-tagged red cells. . . .

Tissue ATP levels corrected for contained blood by ( 51Cr) labeling

51Cr-Tagged red cells were used to determine the red cell content of different tissues. There was good agreement between this method and the benzidine assay of finely homogenized tissue suspensions. This data was then used to correct in vivo tissue ATP concentrations for the ATP content of contaminating red cells. This correction was found to be of importance in granulation tissue and of lesser magnitude in normal liver, renal cortex, muscle and areolar tissue, amounting to less than 10% of the total in these tissues. The method was also applied to in vitro studies and was used to correct tissue [ 14C]ATP specific activity for red cell [ 14C]ATP labeling.

Studies on the pathogenesis of clotting defects during salt-induced abortions

Amniotic fluid was labeled with 51Cr-tagged red cells and 125I RISA before and after intraamniotic infusion of 20 per cent saline for the induction of abortion. The transfer of 125I RISA into the maternal circulation was significantly accelerated by saline infusion (P = < 0.002) and there was a suggestive but not statistically significant rise in the transfer of 51Cr-tagged red cells. Whether the accelerated transfer of amniotic fluid combined with salt infusion is sufficient to trigger the mild DIC seen in these patients is not known.

Effect of denatured plasma on peripheral circulation.

The effect of administration of a longterm perfused plasma on the peripheral circulation was studied by means of the equilibration curve of intravenously injected 51Cr-tagged red cells. The equilibration of 51Cr-tagged red cells was prolonged when a long-term perfused plasma was injected. LMD and ATP were effective in preventing the disturbance of circulation caused by denatured plasma; insulin and NEM were less effective; and cortisone showed a significantly favorable effect. Sequestration of blood in various organs could not be comfirmed in rabbits to which denatured plasma was injected.

Titres, activity or survival? The quantitation of anti-Rh (D) gamma globulin.

The various stimuli leading up to the large-scale preparation of anti-Rh(D) gamma globulin in Australia early in 1967 and subsequently are mentioned. The quantitation of anti-Rh(D) gamma globulin, namely, “titres”, by laboratory serum-albumin titration methods, “activity”, by microgram-permillilitre anti-D estimations made in London and in Melbourne, and “survival”, by radioactivity estimations in Sydney of clearance times of 51Cr-tagged red cells conducted in Rh-negative volunteers, and the necessary quality control tests at various stages of the preparation of gamma globulin are discussed.