ABSTRACT
Aims: The aim of this study is to determine the effect of blood storage using CPDA-1 on packed cell volume, methaemoglobin and oxyhaemoglobin in different ABO/Rhesus blood types donated by some residents of Port Harcourt, Rivers State, Nigeria. Study Design: This is a comparative study aimed at evaluating the effect of storage on the levels of methaemoglobin, oxyhaemoglobin and packed cell volume using CPDA-1. A total of eight donors were recruited with each sample obtained from the eight (8) known blood groups A+,B+,O+,AB+, A-,B-,O-,AB- and analysis of samples were in triplicate. The donors were adult males with age ranging from 35-45 years and they were apparently healthy and free from transfusion transmissible infections. The different blood group samples were stored for 30 days and samples for analysis were collected at 5 days interval. Place and Duration of Study: The study was conducted in Port Harcourt, Rivers State, Nigeria. All blood donors were residents of Port Harcourt. Blood donated was stored at Military Hospital Blood Bank, Port Harcourt, in a blood bag of 450 ml containing 63 ml of citrate phosphate dextrose adenine-1 (CPDA-1). The analysis was carried out at Rivers State University, Post Graduate Laboratory within March 1st to May 27th, 2019. Methodology: A total of eight (8) different ABO/Rhesus blood types (A+,B+,AB+,O+,A-,B-,AB- and O-) were collected and stored using a blood bank refrigerator at temperature of 4°C. Day 0 was taken to be control and 5 days intervals in-between to day 30 acted as the test. Packed cell volume was estimated using micro-haematocrit method while oxyhaemoglobin and methaemoglobin levels were estimated spectrophotometrically as described by Evelyn and Malloy. Results: The result showed a significant decrease in mean packed cell volume, oxyhaemoglobin and methaemoglobin levels compared to a higher mean of these parameters in the control; and these differences were statistically significant (p<0.05) across all blood groups under study. The decrease in values were as a result of haemolysis that occurs during storage. Conclusion: Storage of blood irrespective of the blood group type using CPDA-1 for 30 days indicates that there are “storage lesions”. This is attributed to red cell haemolysis and ageing of red blood cells. In general, all blood types showed no significant difference in their haematological (packed cell volume, methaemoglobin, oxyhaemoglobin) characteristic deterioration or storage lesion based on blood type differences. It is therefore necessary to state that storage lesion characteristics are the same irrespective of the blood type, and that fresh blood be transfused, and if blood is stored, prolonged storage beyond 10 days should be avoided.
ABSTRACT
Oxyhaemoglobins from erythrocytes of different animals including fish, amphibians, reptiles, birds, mammals and human beings have been isolated by ionexchange chromatography over phosphocellulose and the comparative rates of autoxidation of oxyhaemoglobin studied. The mechanism of autoxidation in vitro has been elucidated using toad as well as human oxyhaemoglobin. Autoxidation is markedly inhibited by carbon monoxide as well as by anion ligands, namely, potassium cyanide, sodium azide and potassium thiocyanate. The inhibition by anions is in the same order as their strength as nucleophiles, indicating that it is the oxyhaemoglobin and not the ligandbound deoxy species which undergoes autoxidation. The structure of oxyhaemoglobin is considered to be mainly Hb3+O and determination of the rate of autoxidation with or without using superoxide dismutase and catalase indicates that the initial process of autoxidation takes place by dissociation of Hb3+O to methaemoglobin and superoxide to the extent of 24%. The superoxide thus produced reattacks oxyhaemoglobin to produce further methaemoglobin and hydrogen peroxide. H2O2 is a major oxidant of oxyhaemoglobin producing methaemoglobin to the extent of 53%. A tentative mechanism of autoxidation showing the sequence of reactions involving superoxide, H2O2 and OH has been presented.
ABSTRACT
Superoxide is continuously generated in the erythrocytes, and oxyhaemoglobin from different animals including fish, amphibians, reptiles, birds, flying mammals, mammals and human beings acts as a scavenger of superoxide. The approximate rate constants of the reaction between superoxide and oxyhaemoglobin of different animals are 0·32–1·6 × 107M–1 s–1. Results obtained with anion ligands like CN–- and N indicate that superoxide preferentially reacts with anion ligand-bound deoxyhaemoglobin. Carbonmonoxyhaemoglobin and methaemoglobin are ineffective. Work with photochemically generated oxyradical indicate that oxyhaemoglobin may also act as a scavenger of singlet oxygen. The rate constant of the reaction between superoxide and human oxyhaemoglobin is Kapp= 6·5×106 M–1 s–1, which is about three orders less than KSOD (2× 109 M–1 s–1). Thus, in the erythrocytes, oxyhaemoglobin would appear to act as a second line of defence. Oxyhaemoglobin appears to be as effective as superoxide dismutase for scavenging superoxide in the erythrocytes.