Oral magnesium pidolate: effects of long-term administration in patients with sickle cell disease.

Prevention of erythrocyte dehydration by specific blockade of the transport pathways promoting loss of potassium (K) is a potential therapeutic strategy for sickle cell (SS) disease. Dietary magnesium (Mg) pidolate supplementation over a 4-week period has been shown to inhibit K-Cl co-transport and reduce dehydration. We report here the results in 17 of 20 patients with SS disease treated in an open-label unblinded study of the effects of long-term (6 months) oral Mg pidolate administration (540 mg Mg/d). A significant decrease (P < 0.0025) was observed with Mg therapy in the distribution widths for red cell mean cell haemoglobin concentration (MCHC) (haemoglobin distribution width; HDW), reticulocyte mean cell volume (red cell distribution width of reticulocytes; RDWr) and MCHC (reticulocyte HDW; HDWr), activity of red cell K-Cl co-transport, Na/Mg exchanger and Ca2+-activated (Gardos) K+ channel, whereas red cell K and Mg contents were significantly increased. Hb levels and absolute reticulocyte counts did not change with Mg therapy. Two patients did not complete the trial because of diarrhoea and one did not complete the trial for unrelated reasons. Although the median number of painful days in a 6-month period decreased from 15 (range 0-60) in the year before the trial to 1 (range 0-18; P < 0.0005) during the period of Mg therapy, no firm conclusion on therapeutic efficacy could be drawn from this unblinded open-label trial.

Coinheritance of two alpha-spectrin gene defects in a recessive spherocytosis family.

We studied a recessive hereditary spherocytosis (HS) family from Norway in which all four children had haemolytic spherocytosis while spectrin (Sp) deficiency was detected in the proband. Molecular analysis demonstrated that all affected children had inherited the low expression alpha-Sp allele LEPRA (Low Expressed PRAgue) from the father. Haplotyping with a polymorphic dinucleotide repeat for the alpha-Sp gene (alphaVNTR) located in the 3' untranslated region of mRNA showed that all recessive children had inherited the same maternal alpha-spectrin allele. The paternal Sp-alphaLEPRA allele was found in cis of the polymorphic alpha-Sp Bughill allele (alphaBH) characterized by the A970D point mutation in the Sp alpha-chain. This mutation was identified on two-dimensional electrophoresis of Sp tryptic digests as an acidic shift of the alphaII tryptic domains (spots alphaIIa). Analyses of the relative expression of the paternal alpha-Sp Bughill polymorphism in the proband showed that the product of the maternal alpha-Sp gene is almost completely absent from the mature erythrocyte membrane. Comparative analysis between alphaVNTR PCR-amplified from genomic DNA and from cDNA showed that the maternal low expression alpha-Sp allele is associated with a decreased amount of mRNA. Results from molecular and biochemical studies showed that all the affected children of this family are compound heterozygous for two different low expression alpha-Sp alleles: an uncharacterized defective alpha-Sp allele on the maternal side and an alphaLEPRA allele tagged by the alphaIIa polymorphism on the paternal side.

Recombinant erythropoietin therapy as an alternative to blood transfusions in infants with hereditary spherocytosis.

INTRODUCTION: In hereditary spherocytosis, erythropoiesis has been described as 'sluggish' during the first months of life. The lack of appropriate erythropoietic response to compensate for increased red cell destruction necessitates blood transfusions in 70-80% of hereditary spherocytosis-affected infants during their first year of life. After this period, less than 30% require regular transfusion support. This transient requirement for transfusion led us to wonder whether anemic hereditary spherocytosis infants, like anemic premature infants, could benefit from recombinant erythropoietin therapy (rHu-Epo). MATERIAL AND METHODS: In 16 hereditary spherocytosis infants (age range 16-119 days) with severe anemia, a compassionate open preliminary study was performed. rHu-Epo treatment (1000 IU/kg/week) was instituted together with iron supplementation. Hemoglobin values and reticulocyte counts were repeatedly assessed. RESULTS: In 13 out of 16 infants, prompt increases in reticulocyte counts were noted after the first week of treatment with 1000 IU/kg/week of rHu-Epo. During treatment with Epo these infants maintained clinically acceptable levels of hemoglobin and did not require blood transfusions. As the infants grew and began to mount an adequate erythropoietic response, the rHu-Epo dose could be tapered and the treatment could be discontinued before the age of nine months. CONCLUSION: Epo treatment in most hereditary spherocytosis infants appears to be effective in the management of anemia and could serve as a valuable alternative to packed RBC transfusions.

Oral magnesium supplements reduce erythrocyte dehydration in patients with sickle cell disease.

Intracellular polymerization and sickling depend markedly on the cellular concentration of sickle hemoglobin (Hb S). A possible therapeutic strategy for sickle cell disease is based on reducing the cellular concentration of Hb S through prevention of erythrocyte dehydration. The K-Cl cotransporter is a major determinant of sickle cell dehydration and is inhibited by increasing erythrocyte Mg content. We studied 10 patients with sickle cell disease before treatment and after 2 and 4 wk of treatment with oral Mg supplements (0.6 meq/kg/d Mg pidolate). Hematological parameters, erythrocyte Na, K, and Mg content, erythrocyte density, membrane transport of Na and K, and osmotic gradient ektacytometry were measured. We found significant increases in sickle erythrocyte Mg and K content and reduction in the number of dense sickle erythrocytes. Erythrocyte K-Cl cotransport was reduced significantly. We also observed a significant reduction in the absolute reticulocyte count and in the number of immature reticulocytes. Ektacytometric analysis showed changes indicative of improved hydration of the erythrocytes. There were no laboratory or clinical signs of hypermagnesemia. Mild, transient diarrhea was the only reported side effect. We conclude that oral Mg supplementation reduces the number of dense erythrocytes and improves the erythrocyte membrane transport abnormalities of patients with sickle cell disease.