Hemolysis measurements

The interaction of irritating substance with the cell membrane can also be measured if red blood cells are used. With a photometric determination the hemolysis (L f) and denaturation (D f) is measured. The ratio LID is an expression for the dermatological compatibility. Low LID figures describe a certain irritation, high LID figures describe a substance as mild. Results found for the... 

Certain of these peptoid antibiotics are also selective for bacterial, rather than mammalian, cells. The selectivity of these peptoids has been measured in terms of their capacity to cause hemolysis of human erythrocytes at or near their MIC (Tab. 1.3). Interestingly, the amount of hemolysis induced by these peptoids correlates well with their hydrophobicity as there is an increasing extent of hemolysis as molecular hydrophobicity increases. These results suggest that highly hydro-phobic compounds of this class are poorly selective antibiotics. The most active antibacterial peptoids, T2-15 and T3-12, have quite low hemolytic activity near their MICs. Although highly antibacterial in vitro, T3-17 is also very hemolytic at its MIC value. 

Recently, in a study of the various methods for doing proteins in amniotic fluid it was noted that values ranging up to 12% have been reported in literature. What was being measured in these cases was the turbidity and the presence of hemolysis in amniotic fluid. When the Bloor s reagent extract is applied, substantially lower and more consistent values were obtained (47). 

With arsine exposure, there may be potential severe hemolysis (the breakdown of red blood cells and the release of hemoglobin). Ensure adequate oxygenation by arterial blood measurement or pulse oxygenation monitoring. Use diuretics to maintain urinary flow. 

Another proposed in vitro assay for muscle irritancy for injectable formulations is the red blood cell hemolysis assay (Brown et al., 1989). Water-soluble formulations in a 1 2 ratio with freshly collected human blood are gently mixed for 5 min. The percentage of red blood cell survival is then determined by measuring differential absorbance at 540 nm this value is then compared to values for known irritants and nonirritants. Against a very small group of compounds (four), this assay reportedly accurately predicts muscle irritation. 

Additional considerations for topically (dermal, intransal, introral, ophthalmic, rectal or vaginal) or pulmonary adminstered excipients are ocular irritation, sensitisation, oral or parenteral route toxicity studies additional considerations for injectable excipients are an in vitro hemolysis study, measurement of creatinine kinase and protein binding evaluation where appropriate new excipients should also be examined for photosafety. 

Biocompatibility of injectable formulations with tissues can be tested by observing microscopic histology of the tissues so exposed, or by using erythrocyte hemolysis as a surrogate for these other tissues. Alternatively, one can measure the level of the cytosolic enzyme creatine phosphokinase that is released from damaged tissues (18). 

Bioassay methods include measurements of quantity required to prevent fetal resorption and for red blood cell hemolysis (in rat). Measurements also are made of liver storage in the chick. Physicochemical methods used include colorimetric two-dimensional paper chromatography,... 

Selectivity is the ability of an assay to measure the analyte of interest in the presence of other constituents in the sample. Because IAs are often performed without sample extraction, they are more prone to matrix interference than are chromatographic methods with extraction. Matrix interference could come from crossreactivity with structurally similar components in the sample, or from nonspecific binding to structurally dissimilar components in the matrix. The results are high background noise, loss of sensitivity, and inaccurate and nonreproducible data. Sometimes, the problem may only occur in a few exceptional patient samples that have structurally similar components such as unknown metabolites, or dissimilar components from samples with hyperlipidemia, hemolysis, complement components, rheumatoid factors, binding proteins, autoantibodies, and heterophilic anti-immunoglobulin Ab. 

Several preanalytical factors can cause a false elevation of the measured plasma ammonium concentration. These include prolonged tourniquet application, hemolysis, specimen transportation at room temperature, delay in plasma separation, and even ambient ammonium from cleaning agents or cigarette smoke. These fac-... 

However, blood CO is still measured by determining COHb levels, which are normally undetectable but might be involved in the transfer of CO between cells. The measurement of COHb is useful not only in the quantification of CO but also to detect neonatal hemolysis (Necheles et al, 1976 Ostrander et al, 1982). 

Hemolysis is determined by placing powder, rods, or extracts of a material in contact with human or animal plasma for about 90 minutes at 37°C (31). The amount of hemoglobin released into solution after lysis of the red cells in contact with the device is measured. When red cells undergo lysis, hemoglobin is released from the cells, and the absorbance from released hemoglobin is proportional to the amount of cell lysis. Extensive red-cell lysis is not desirable for devices that are to be implanted in the cardiovascular system. The measurement of hemolysis and its relevance is a question that should be addressed it each device application. 

The most direct method for measurement of tonicity obviously would be to observe changes in erythrocytes on mixing solution with blood. If hemolysis or crenation or a marked change in the appearance of erythrocytes occurs, the solution is not isotonic. If the cells retain their normal size and shape, the solution is isotonic. Grosicki and Husa used this method early on ... 

A 33-year-old white woman presented with weight loss, anemia, thrombocytopenia, hemolysis, liver dysfunction (transaminase activities 15-20 times normal, total bilirubin three times normal), and renal insufficiency. She had taken chromium picolinate 1200-2400 micrograms/day for the previous 4-5 months to enhance weight loss. Her plasma chromium concentrations were 2-3 times normal. After withdrawal of chromium picohnate, she was managed with supportive measures, blood transfusions, and hemodialysis. The hemolysis stabilized and her liver and renal function eventually recovered. 

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