Comparison of oxidative stress and the frequency of polymorphisms in the HFE gene between hemoglobin S trait blood donors and sickle cell disease patients.

It is well documented that Hb S and iron affect blood cells, and trigger oxidative processes and generation of free radicals with potential for lipid peroxidation. We evaluated the frequency of polymorphisms in the HFE gene in Hb AS blood donors and how these polymorphisms influenced lipid peroxidation and antioxidant capacity. Blood samples were collected from 211 Hb AS blood donors, 119 Hb AA blood donors as a control group, and 28 sickle cell disease patients (Hb SS). The H63D allele was found at a frequency of 10.5% in the Hb AS samples, and the C282Y allele frequency was 0.7%. In the control group, the frequencies of the H63D and C282Y alleles were 13.4 and 2.1%, respectively. In the sickle-cell disease patients, the H63D and the C282Y allele frequencies were 10.7 and 3.5%, respectively. The frequencies of the C282Y and H63D polymorphisms in Hb AS blood donors are similar to those reported for the Brazilian population. Serum malondialdehyde values, indicative of lipid peroxidation, were highest in sickle cell patients, independent of the polymorphisms in the HFE gene, with significant differences, showing the influence of Hb S allele in the levels of lipid peroxidation. However, the trolox equivalent antioxidant capacity average levels, indicative of the antioxidant capacity, were reduced with significant differences, indicating that in spite of a lipid peroxidation raise, this is not followed by the increased of the antioxidant capacity, leading to oxidative stress.

In vivo tissue characterization using magnetic techniques.

Among the few non-invasive methods to quantify liver iron deposits, magnetic resonance imaging (MRI) and biomagnetic liver susceptometry (BLS) have been considered the best to evaluate iron overload in the body. This diagnosis is necessary for patients who regularly receive red blood cells transfusion and that have a genetic disorder known as hemochromatosis. In this work, we present the evaluation of the clinical usefulness of MRI and BLS of hepatic tissue to quantify iron deposits in non-transfused and transfused patients. Liver iron evaluation by MRI and BLS were performed in a group of 48 patients. The MRI images weighted in T2 were acquired using multi-slice single-spin-echo (SSE) and single-slice multi-spin-echo (MSE), conducted on a 1.5 T whole body scanner. BLS measurements were performed using an ac superconducting susceptometer based on SQUID. Typically MRI is able to evaluate iron overload in liver as high as 30 mg/g(dry tissue) when using MRI scanners provided with specially designed pulse sequences. For higher iron concentrations susceptibility measurement works better than MRI to evaluate higher iron overloads in the liver, because in this case there is saturation of MRI signal.

Antierythrocyte antibodies in hemodialysis and kidney transplant patients.

Natural antierythrocytic antibodies may be stimulated by bacterial antigens and the immune type may occur as a result of pregnancy or blood transfusions. The prevalence increases with the number of red cell units transfused. Specificity, on the other hand, depends on ethnic backgrounds. The clinical importance of these antibodies is to precipitate hemolytic transfusion reactions and erythroblastosis fetalis. Hemodialysis patients are multitransfused and have a quite variable prevalence of antibodies. Kidney transplant patients with blood group identity do not form antibodies. We studied the presence of both types of antierythrocytic antibodies (natural and immune) in hemodialysis and kidney transplant patients in Brazilian blood transfusion and nephrology services.