Haematological Profile of Children With Sickle Cell Anaemia in Steady State.

Introduction Sickle cell anaemia (SCA) is an inherited, autosomal recessive condition that results from a mutation in the ß-globin gene. Vascular occlusion is the underlying mechanism behind a myriad of complications encountered. This vascular occlusion is primarily caused by the increased tendency of red blood cells (RBC) to adhere to the vascular endothelium, and the activation of platelets and total leucocyte count (TLC), hence the need for a steady-state haematological profile in these patients. Method This was a cross-sectional study conducted over four months at a sickle cell clinic. Haemoglobin (Hb) concentration, haematocrit, platelet, TLC, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) of the subjects were recorded and analysed. Results Ninety-nine subjects aged 1-18 years were recruited for the study. There were 53 (53.5%) males. Leucocytosis was seen in 80 (80.8%), anaemia in 99 (100%), and thrombocytosis in 30 (30.3%) patients. The mean Hb, TLC and platelets were 7.9 ± 1.3g/dl, 14.3 ± 4.5 x 103/mm3 and 391.5 ± 182.6 x 103/mm3 respectively. Mean MCV, MCH and MCHC were 81.3 ± 7.1 fl, 28.6 ± 2.9 pg and 35.2 ± 1.7 g/dl respectively. Children aged one to four years had the highest TLC (p=0.002) but the lowest mean Hb and platelet (p=0.094 and 0.06) respectively. The mean MCV, MCH and MCHC were lowest in children aged one to four years (p=0.047, 0.001 and 0.001). Conclusion Anaemia, leucocytosis and thrombocytosis are characteristics features of children with SCA, especially in male and younger subjects. Although Iron markers are generally normal in children with SCA, those under the age of five years tend to have lower values.

Cross-linking with bifunctional reagents and its application to the study of the molecular symmetry and the arrangement of subunits in hexameric protein oligomers.

Cross-linking with a bifunctional reagent and subsequent SDS gel electrophoresis is a simple but effective method to study the symmetry and arrangement of subunits in oligomeric proteins. In this study, theoretical expressions for the description of cross-linking patterns were derived for protein homohexamers through extension of the method used for tetramers by Hajdu et al. (1976). The derived equations were used for the analysis of cross-linking by glutardialdehyde of four protein hexamers: beef liver glutamate dehydrogenase (GDH), jack bean urease, hemocyanin from the spiny lobster Panulirus pencillatus (PpHc), Escherichia coli glutamate decarboxylase (GDC) and for analysis of published data on the cross-linking of hexameric E. coli rho by dimethyl suberimidate. Best fit models showed that the subunits in the first four proteins are arranged according to D(3) symmetry in two layers, each subunit able to cross-link to three neighboring subunits for GDH and urease, or to four for PpHc and GDC. The findings indicate a dimer-of-trimers eclipsed arrangement of subunits for GDH and urease and a trimer-of-dimers staggered one for PpHc and GDC. In rho, the subunits are arranged according to D(3) symmetry in a trimer-of-dimers ring. The conclusions from cross-linking of GDH and GDC, PpHc and rho are consistent with results from X-ray crystal structure, those for urease with findings from electron microscopy.

Apparent specific volume of human hemoglobin: effect of ligand state and contribution of heme.

The apparent specific volumes of human deoxy-, oxy-, met-, and CN-met hemoglobin (Hb) were measured with a vibrating tube densitometer. The values were calculated from the difference in density between protein solutions and solvents with which they were in dialysis equilibrium. The results obtained were very similar to the value for horse HbCO often used for sedimentation studies of Hbs. The apparent specific volumes of oxy- and CN-metHb are approximately 0.0020 cm(3)/g higher than those of deoxy- and metHb. This small reproducible difference could be due either to a small conformational difference between the liganded and unliganded species or to different interactions with components of the solvent. On the basis of these results, a simple method for the determination of the contribution of the heme to the apparent specific volume is proposed. The contribution can be estimated from the difference between the measured volume of each molecular species and that calculated from the amino acid composition.

On the molecular mass of Lumbricus erythrocruorin.

A critical examination of the published molecular mass of erythrocruorin (Ec) from Lumbricus and related earthworm species reveals that the results do cluster, not at one, but at two values of the molecular mass. One cluster corresponds to approximately 3.6 MDa as predicted from the Vinogradov model for the hexagonal bilayer (HBL) assembly of Lumbricus terrestris EC and as estimated from the crystal structure of HBL at 5.5 A resolution. The other cluster corresponds to approximately 4.4 MDa. However, in contrast to the controversy over the molecular mass, there is a consensus that the sedimentation coefficient of intact L. terrestris Ec is approximately 60S. Drawing on the occurrence of central subunits in Ec of Oenone fulgida and few other annelid species, we propose for the 4.4 MDa molecule a model of HBL supplemented by a central mass. The proposed model abides by D6 symmetry and is a suitable candidate to represent 60S Lumbricus terrestris Ec.

Towards a resolution of the long-standing controversy regarding the molecular mass of extracellular erythrocruorin of the earthworm Lumbricus terrestris.

The published molecular mass of erythrocruorin of Lumbricus terrestris and related earthworm species covers a bewildering range of 3.23-4.5 MDa. A critical reexamination reveals that some mass determinations were underestimated and the results do cluster, not at one, but at two values of the molecular mass. One cluster corresponds to approximately 3.6 MDa, as predicted for a stoichiometry of 144 globin and 36 linker chains-the Vinogradov model for the hexagonal bilayer (HBL) assembly of Lumbricus erythrocruorin-and as estimated from the crystal structure of HBL at 5.5 A resolution [Proc. Natl. Acad. Sci. U. S. A. 97 (2000) 7107]. The other cluster corresponds to approximately 4.4 MDa. In addition, a molecular mass of 4.1 MDa, determined by multiangle laser light scattering (MALLS), stands apart of the two clusters, separated from the masses obtained by other methods of molecular mass determination. We propose a stoichiometry of 192 globin and 36 linker chains for the 4.4-MDa molecule. The 36 linkers and 144 out of 192 globin chains are identified with the HBL and the remaining 48 globins are allotted equally to the two halves of the axial cavity above and below the central torus of the structure. The proposed model is supported by the occurrence in some annelid species of erythrocruorin with centrally placed subunits [Biochim. Biophys. Acta 359 (1974) 210], and by the oxidation-dependent shedding of subunits in Lumbricus erythrocruorin. We propose further that the 4.1 MDa determination represents the weight average molecular mass of a population of molecules resulting from a partial dissociation of 4.4-MDa erythrocruorin. This interpretation seems reasonable on the background of the very low protein concentrations ( approximately 100 microg/ml and lower) prevailing at the MALLS experiment.