Oxidative Modification of Low-Density Lipoprotein and Atherogenetic Risk in β-Thalassemia

Detection and inhibition of lipid-derived radicals in low-density lipoprotein

Oxidized low density lipoprotein (Ox-LDL) is implicated in a variety of oxidative diseases. To clarify the mechanisms involved and facilitate the investigation of therapeutics, we previously developed a detection method for lipid-derived radicals using the fluorescent probe 2,2,6-trimethyl-6-pentyl-4-(4-nitrobenzo[1,2,5]oxadiazol-7-ylamino)piperidine-1-oxyl (NBD-Pen). In this study, NBD-Pen was used to detect lipid-derived radicals in Ox-LDL from in vitro and in vivo samples using an iron overloaded mouse model. By following the timeline of lipid radical generation using this method, the iron overloaded mice could be successfully treated with the antioxidant Trolox, resulting in successful lowering of the plasma lipid peroxidation, aspartate transaminase and alanine transaminase levels. Furthermore, using a combination therapy of the chelating agent deferoxamine (DFX) and Trolox, liver injury and oxidative stress markers were also reduced in iron overloaded mice. The NBD-Pen method is highly sensitive as well as selective and is suitable for targeting minimally modified LDL compared with other existing methods.

Premature atherosclerosis in children with beta-thalassemia major: New diagnostic marker

Background

Early vascular alteration, atherosclerosis and coronary artery disease have emerged as important cardiovascular complications among beta-thalassemia major (B-TM) patients. The aims of the current study were to assess the prevalence of premature atherosclerosis among our B-TM patients, and to investigate the diagnostic value of serum Osteoprotegerin assay as an early biomarker for atherosclerosis.

Methods

This cross-sectional study was conducted at Hematology unit - Pediatric Department, Zagazig University Children Hospital- Egypt in the period from March 2014 to March 2015. A total of 115 children were enrolled in the current study; as sixty-five (65) children with beta thalassemia major aged 5–18 years, on regular blood transfusion regimen represented the patient group. While fifty (50) healthy children, with comparable age and gender, were assigned as control group. All participants were subjected to history taking, thorough clinical examination and laboratory investigations including; complete blood count, liver and kidney function tests, C- reactive protein, lipid profile, serum ferritin and serum Osteoprotegerin (OPG) assay. Also, carotid artery intima media thickness (CAIMT) was performed by duplex ultrasound for patients and controls.

Results

Our B-TM patients were transfusion-dependent for as long as 8.5 ± 3.8 years with significantly higher serum ferritin levels (2490 ± 1579 ng/dl vs 83 ± 32 ng/dl, p = 0.001), C-reactive protein (5.7 ± 5.7 vs 0.9 ± 0.9), liver enzymes and bilirubin when compared to controls. Significantly higher serum triglyceride (128 ± 20 vs 101 ± 7 mg/dL, p = 0.009) and atherogenic index of plasma (0.45 ± 0.12 vs 0.22 ± 0.04, p = 0.001) were recorded in patients than comparisons. On the contrary, total serum cholesterol (116 ± 16 vs 143 ± 5, p < 0.001), low density lipoprotein-cholesterol (LDL-C) (44 ± 9 vs 73 ± 6, p < 0.001) and high density lipoprotein cholesterol (HDL-C) (39 ± 2 vs 61 ± 5, p < 0.001), were significantly lowered in patients versus normal peers. Carotid arteries intima media thickness (CAIMT) of both side were significantly increased for patients (Rt 0.62 ± 0.2 vs. 0.29 ± 0.07 mm, p = 0.001 & Lt 0.66 ± 0.17 vs 0.29 ± 0.05 mm, p = 0.001) when compared with healthy controls, and showed positive correlation with, serum triglyceride, atherogenic index of plasma, and serum Osteoprotegerin levels. ELISA assay of serum Osteoprotegerin (OPG) revealed significantly higher levels for thalassemia patients than matched healthy controls (427 ± 102 vs. 324 ± 126 pg/ml, p = 0.02). Of particular interest is the obvious positive correlation between OPG levels and CAIMT of both sides (Rt r 0.54, p = 0.001 &Lt r 0.479, p = 0.001) and also with serum triglycerides (r 0.374, p = 0.03).

Conclusions

Subclinical atherosclerosis started prematurely in children with beta- thalassemia. Carotid artery intima media thickness represented a simple, accurate and non-invasivemodality for early detection ofatherosclerosis. It was correlated well with serum Osteoprotegerin; this finding highlighted the possible validity of OPG assay as an early predictor of atherosclerosis in thalassemia children.

Impact of Genetic Polymorphism of methylenetetrahydrofolate reductase C677T on Development of Hyperhomocysteinemia and Related Oxidative Changes in Egyptian β-Thalassemia Major Patients

BACKGROUND

β-thalasemia major (β-TM) patients often suffer from various vascular complications together with increased oxidative stress. Hyperhomocysteinemia (Hhcy) has been defined as a risk factor for these complications. Genetic polymorphism of methylenetetrahydrofolate reductase (MTHFR) C677T has been shown to cause Hhcy particularly in individuals with low B-vitamins. However, the status of homocysteine (hcy) in β-TM has not yet been adequately defined.

AIM

To evaluate the genetic polymorphism of MTHFR C677T among β-TM patients and its prospective contribution to Hhcy and related oxidative changes.

SUBJECTS AND METHODS

Genotyping for MTHFR C677T was done by PCR-RFLP technique. Plasma hcy, vitamin B12, folate, malondialdehyde (MDA), total antioxidant capacity (TAC), oxidized low density lipoprotein (oxLDL), total nitric oxide (NOx) and lipid profile were determined in 66 β-TM patients and 66 control subjects of matched age and sex.

RESULTS

The prevalence of MTHFR 677TT genotype was significant among β-TM patients (12%) compared to (3%) controls (OR = 4.9, 95%CI:1.2-24.2,P = 0.03). A strong association between Hhcy and MTHFR TT genotype was observed (OR = 7.7, 95%CI:2.8-20.9) where all β-TM patients with TT genotype were hyperhomocystienemic (≥ 15 μmol/l) and having sub-optimal folate level than those with CT or CC genotypes. Hyperhomocystienemic patients have suffered from increased oxidative stress characterized by significant increase in plasma MDA and oxLDL, and a significant reduction of plasma TAC and total NOx. Lipid profile of those patients was severely affected indicated by reduction in HDL and HDL/LDL and elevation in atherogenic index as compared with CC genotype. Other measured parameters were not significantly different among β-TM patients with different MTHFR genotypes.

CONCLUSION

This study suggests that Egyptian β-TM patients with MTHFR 677TT genotype could be at increasing risk of developing Hhcy particularly with folate deficiency. This state of Hhcy may account potentially for most oxidative changes and atherogenic vascular complications frequently reported in β-TM patients.

Carotid Intima-Media Thickness and Oxidative Stress Markers for Assessment of Atherosclerosis in Children with β Thalassemia Major

The present study evaluates carotid intimamedia thickness (CIMT) in children with β thalassemia major to assess atherosclerosis and its relation to the underlying proposed causative mechanisms via lipid peroxidation product malondialdehyde (MDA), oxidized lowdensity lipoproteins (LDL), total antioxidant level, and lipid profile. A cross sectional study was conducted on 62 children (31 cases and 31 controls). CIMT by high resolution ultrasound and biochemical parameters i.e., total cholesterol, triglycerides, high-density lipoproteins, LDL, Oxidized LDL, lipoprotein (a), lipid peroxidation product MDA and total antioxidant were measured in enrolled subjects and compared. In our study, CIMT was significantly increased in β thalassemia major patients’ as compared to healthy controls. Mean CIMT in cases was 0.69 ± 0.11 mm and in controls 0.51 ± 0.07 mm. Mean oxidized LDL (EU/mL) in cases 39.3 ± 34.4 (range 14.4 to 160) was significantly raised (p = 0.02, t test) as compared to controls 23.9 ± 13.4 (range 12 to 70). In our study we found MDA levels (nmol/mL) to be increased in β thalassemia patients as compared to controls. Mean MDA was 10.0 ± 3.27 (4.41 to 17.48) in cases while in controls was 6.87 ± 4.55 (1.5 to 17.9). Our study results show CIMT as an early marker of atherogenesis in β thalassemia major. Oxidative stress markers are also increased in β thalassemia major patients and lipoprotein (a) shows a positive correlation with CIMT. The present study points towards various atherogenetic mechanisms in β thalassemia major.

Atherogenesis and iron: from epidemiology to cellular level

Iron accumulates in human atherosclerotic lesions but whether it is a cause or simply a downstream consequence of the atheroma formation has been an open question for decades. According to the so called "iron hypothesis," iron is believed to be detrimental for the cardiovascular system, thus promoting atherosclerosis development and progression. Iron, in its catalytically active form, can participate in the generation of reactive oxygen species and induce lipid-peroxidation, triggering endothelial activation, smooth muscle cell proliferation and macrophage activation; all of these processes are considered to be proatherogenic. On the other hand, the observation that hemochromatotic patients, affected by life-long iron overload, do not show any increased incidence of atherosclerosis is perceived as the most convincing evidence against the "iron hypothesis." Epidemiological studies and data from animal models provided conflicting evidences about the role of iron in atherogenesis. Therefore, more careful studies are needed in which issues like the source and the compartmentalization of iron will be addressed. This review article summarizes what we have learnt about iron and atherosclerosis from epidemiological studies, animal models and cellular systems and highlights the rather contributory than innocent role of iron in atherogenesis.

Nutritional biomarkers in children and adolescents with Beta-thalassemia-major: An Egyptian center experience

BACKGROUND AND AIM

Trace elements and vitamins play a vital role in human body to perform its function properly. Thalassemic patients are at risk of micronutrient deficiency. This study estimated levels of vitamins A, C, E, B12, folic acid, total homocysteine (tHcy), and methylmalonic acid (MMA) along with trace elements, zinc, copper, and selenium in Beta-thalassemia-major patients.

METHODS

This study included 108 patients with Beta-thalassemia-major and 60 age and sex matched healthy children. Serum levels of vitamin A, E, C, tHcy, and MMA were estimated by high pressure liquid chromatography while serum levels of folic acid and B12 were estimated by thin layer chromatography. Serum zinc, copper, and selenium were determined by atomic absorption spectrometry.

RESULTS

There was a significant decrease of vitamins A, C, E, and B12 and trace elements zinc, copper, and selenium in thalassemic patients as compared to controls. tHcy and MMA were significantly elevated in patients. No significant correlations were found between the serum levels of the studied vitamins and trace elements as regards age, frequency of transfusion, duration of transfusion, and serum ferritin.

CONCLUSION

The level of various nutritional biomarkers (vitamins A, C, E, and B12 and trace elements zinc, copper, selenium) was reduced in chronically transfused Egyptian thalassemic patient. These patients should have periodic nutritional evaluation and supplementation. Multicenter studies are highly recommended.

Flow cytometric assessment of circulating platelet and erythrocytes microparticles in young thalassemia major patients: relation to pulmonary hypertension and aortic wall stiffness

Heart disease is the leading cause of mortality and morbidity in β-thalassemia major (β-TM). Aggregability of abnormal red cells and membrane-derived microparticles (MPs) stemming from activated platelets and erythrocytes are responsible for thrombotic risk. We measured platelet and erythrocyte MPs (PMPs and ErMPs) in 60 young β-TM patients compared with 40 age- and sex-matched healthy controls and assessed their relation to clinicopathological characteristics and aortic elastic properties. Patients were studied stressing on transfusion history, splenectomy, thrombotic events, chelation therapy, hematological and coagulation profiles, flow cytometric measurement of PMPs (CD41b(+) ) and ErMPs (glycophorin A(+) ) as well as echocardiographic assessment of aortic elastic properties. Aortic stiffness index and pulmonary artery pressure were significantly higher, whereas aortic strain and distensibility were lower in TM patients than controls (P < 0.001). Both PMPs and ErMPs were significantly elevated in TM patients compared with controls, particularly patients with risk of pulmonary hypertension, history of thrombosis, splenectomy or serum ferritin >2500 μg/L (P < 0.001). Compliant patients on chelation therapy had lower MPs levels than non-compliant patients (P < 0.001). PMPs and ErMPs were positively correlated to markers of hemolysis, serum ferritin, D-dimer, vWF Ag, and aortic stiffness, whereas negatively correlated to hemoglobin level and aortic distensibility (P < 0.05). We suggest that increased MPs may be implicated in vascular dysfunction, pulmonary hypertension risk, and aortic wall stiffness observed in thalassemia patients. Their quantification could provide utility for early detection of cardiovascular abnormalities and monitoring the biological efficacy of chelation therapy.

Protein antioxidants in thalassemia

It is common knowledge that thalassemic patients are under significant oxidative stress. Chronic hemolysis, frequent blood transfusion, and increased intestinal absorption of iron are the main factors that result in iron overload with its subsequent pathophysiologic complications. Iron overload frequently associates with the generation of redox-reactive labile iron, which in turn promotes the production of other reactive oxygen species (ROS). If not neutralized, uncontrolled production of ROS often leads to damage of various intra- and extracellular components such as DNA, proteins, lipids, and small antioxidant molecules among others. A number of endogenous and exogenous defense mechanisms can neutralize and counteract the damaging effects of labile iron and the reactive substances associated with it. Endogenous antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, and ferroxidase, may directly or sequentially terminate the activities of ROS. Nonenzymatic endogenous defense mechanisms include metal binding proteins (ceruloplasmin, haptoglobin, albumin, and others) and endogenously produced free radical scavengers (glutathione (GSH), ubiquinols, and uric acid). Exogenous agents that are known to function as antioxidants (vitamins C and E, selenium, and zinc) are mostly diet-derived. In this review, we explore recent findings related to various antioxidative mechanisms operative in thalassemic patients with special emphasis on protein antioxidants.

Plasma protein oxidation is correlated positively with plasma iron levels and negatively with hemolysate zinc levels in sickle-cell anemia patients

INTRODUCTION

Sickle-cell anemia (SCA) is a disease of high oxidative stress. The oxidative medium of SCA was evaluated by protein oxidation parameters and their correlation with lipids and ions were investigated both in the plasma and in the erythrocyte.

METHODS

Blood samples were obtained from 15 steady-state patients with SCA, 10 carriers, and 10 controls. Plasma protein carbonyl, total sulfhydryl, total cholesterol, triglyceride, phospholipids, and bilirubin levels were determined by spectrophotometric methods. Plasma copper, zinc, and iron levels were determined by atomic absorption spectrophotometry. Levels of cholesterol, triglyceride, and ions were also determined in the hemolysate lipid extract.

RESULTS

Patients had increased protein carbonyl and decreased total sulfhydryl levels compared with controls. Plasma cholesterol levels were lower than controls, and triglyceride levels were higher than carriers in patients with SCA. Plasma iron and hemolysate copper were higher in patients than carriers and controls. Plasma protein carbonyl levels were found to be correlated with plasma iron and hemolysate zinc levels in the patient group.

CONCLUSION

Alterations of proteins, lipids, and ions in the plasma and erythrocyte of steady-state patients with SCA were demonstrated. Some of these alterations are related with each other and with the oxidative stress observed in the disease.

Oxidative modification and poor protective activity of HDL on LDL oxidation in thalassemia

Oxidative modification of low-density lipoprotein (LDL) has been reported in thalassemia, which is a consequence of oxidative stress. However, the levels of oxidized high-density lipoprotein (HDL) in thalassemia have not been evaluated and it is unclear whether HDL oxidation may be linked to LDL oxidation. In this study, the levels of total cholesterol, iron, protein, conjugated diene (CD), lipid hydroperoxide (LOOH), and thiobarbituric acid reactive substances (TBARs) were determined in HDL from healthy volunteers and patients with beta-thalassemia intermedia with hemoglobin E (beta-thal/Hb E). The protective activity of thalassemic HDL on LDL oxidation was also investigated. The iron content of HDL(2) and HDL(3) from beta-thal/HbE patients was higher while the cholesterol content was lower than those in healthy volunteers. Thalassemic HDL(2) and HDL(3) had increased levels of lipid peroxidation markers i.e., conjugated diene, LOOH, and TBARs. Thalassemic HDL had lower peroxidase activity than control HDL and was unable to protect LDL from oxidation induced by CuSO(4). Our findings highlight the oxidative modification and poor protective activity of thalassemic HDL on LDL oxidation which may contribute to cardiovascular complications in thalassemia.

Prolidase activity and oxidative status in patients with thalassemia major

AIM

Prolidase is a specific imidodipeptidase involved in collagen degradation. The increase in the enzyme activity is believed to be correlated with the increased intensity of collagen degradation. The study aimed to evaluate the relationship between prolidase activity and oxidative status in patients with thalassemia major.

METHODS

Comparison was made between 87 patients diagnosed with thalassemia major and 33 healthy children of similar age and gender. Mean age of the subjects was 7.5+/-4.3 years in the group of patients with thalassemia major and 8.9+/-3.1 years in the control group. Serum prolidase activity was measured spectrophotometrically. Oxidative status was determined using total oxidant status (TOS), total antioxidant capacity (TAC), and oxidative stress index (OSI) measurement.

RESULTS

Prolidase activity was significantly increased in patients with thalassemia major (53.7+/-8.7 U/l) compared to the control group (49.2+/-7.2 U/l, P<0.001). TOS was significantly increased in the patient group (5.31+/-3.14 mmol H2O2 equiv./l) compared to the control group (3.49+/-2.98 mumol H2O2 equiv./l) and the OSI was also significantly increased in the patient group (3.86+/-3.28 arbitrary unit) compared to the control group (2.53+/-2.70 arbitrary unit) (P<0.0001 and P<0.001, respectively), while there were no significant differences between the patient (1.61+/-0.30 mumol Trolox equiv./l) and control (1.64+/-0.33 mumol Trolox equiv./l) groups with respect to TAC.

CONCLUSION

Significant increases in prolidase activity in patients with thalassemia major may constitute a key parameter in demonstrating a disorder of the collagen metabolism.

Association between apolipoprotein ε4 allele, factor V Leiden, and plasma lipid and lipoprotein levels with sickle cell disease in Southern Iran

To investigate whether there is any association between various APOE alleles and factor V Leiden (FVL) with lipid profiles and sickle cell disease (SCD) in Southern Iran. 65 SCD patients consisting of 35 sickle cell anemia homozygous (SS), 15 sickle cell heterozygous (AS) and 15 sickle cell/βThalassemia (S/βthal) patients and 68 healthy individuals with normal hematological indices were studied. APOE and FVL polymorphisms were detected by PCR-RFLP and serum lipid level was measured enzymatically. The frequencies of FVL and APOE-ε4 allele were significantly higher in SCD patients than in control (15.4 vs. 4.4 and 13.7% vs. 3.3%, respectively). The distributions of APOE ε3ε3, ε2ε3 and ε2ε4 + ε3ε4 alleles in SCD patients were significantly different from those in the control group. The SCD subjects particularly SS/S βthal (SS + S/βthal) and SS patients have significantly lower frequency of APOE ε3ε3 allele (P < 0.05) whereas SCD, SS patients and AS individuals have a significantly higher frequency of APOE ε4 allele (ε2ε4 + ε3ε4; P = 0.003, P = 0.011 and P = 0.035, respectively) compared to the control group. The LDL-C (P = 0.006) and total cholesterol (P < 0.001) levels in SCD subjects were found to be significantly lower than those in the control group. In addition, the presence of non-APOE ε4 allele (ε2ε3 + ε3ε3) resulted in a significant decrease in the level of LDL-C and total cholesterol in SCD subjects in general and in SS and SS/S βthal patients in particular compared to controls. Furthermore, the presence of APOE ε4 allele (ε2ε4 + ε3ε4) was found to be associated with the risk of sickle cell anemia [OR = 4.1, P = 0.04]. The presence of either FVL mutation (OR = 4.6; CI: 0.91-24, P = 0.07) or APOE-ε4 allele (OR = 4.07; CI: 1.01-16.4, P = 0.048) is associated with the risk of sickle cell disease in Southern Iran. This data suggest that the activation of coagulation system enhances thrombus generation and decreases antioxidant activity in SCD patients from Southern Iran.

Paraoxonase and arylesterase activity with oxidative status in children with thalassemia major

PURPOSE

The aim of this study was to study paraoxonase and arylesterase activities along with oxidative status parameters, and to find out whether there is any increased susceptibility to atherogenesis, which might be reflected with increased oxidative stress and decreased serum paraoxonase/arylesterase activity in beta-thalassemia major (BTM) patients.

PATIENTS AND METHODS

Eighty-seven patients with BTM and 33 healthy individuals were enrolled in the study.

RESULTS

Paraoxonase and arylesterase activities were significantly lower in BTM patients than controls (for all P<0.0001), whereas total oxidant status, total peroxide concentration levels, and oxidative stress index were significantly higher (P<0.0001, <0.0001, and <0.001, respectively). Correlations were found between serum iron and ferritin and levels of total oxidant status in BTM patients. Significant correlation was found with serum total peroxide concentration levels and paraoxonase and arylesterase activities in patients with BTM.

CONCLUSIONS

It was seen that oxidative stress increases, while serum paraoxonase activity is decreased in BTM patients. Decrease in paraoxonase activity seems to be associated with both the degree of oxidative stress and anemia. BTM patients may be more prone to development of atherogenesis because of low serum paraoxonase/arylesterase activity.

Quantitative determination of ortho- and meta-tyrosine as biomarkers of protein oxidative damage in beta-thalassemia

Oxidative stress in thalassemia is caused by secondary iron overload and stems from blood transfusion and increased iron uptake. In this study, we hypothesized that levels of o- and m-tyrosine, products of hydroxyl radical attack on phenylalanine, would be elevated in beta-thalassemia (intermediate). This study represents the first report in which specific markers of protein oxidative damage have been quantified in thalassemia. We used GC/MS to assay o- and m-tyrosine at the femtomole level using only a few microliters of plasma. Levels of both markers were significantly higher in patients with beta-thalassemia than in controls and were positively correlated with serum ferritin, malondialdehyde, superoxide dismutase, glutathione peroxidase and glutathione. We conclude that o- and m-tyrosine are useful biomarkers of oxidative damage to proteins in thalassemia (intermediate) and may also be useful markers in other iron overload diseases. Positive correlations between o- and m-tyrosine levels and malondialdehyde as well as antioxidants such as superoxide dismutase, glutathione peroxidase and glutathione, are indicative of the broad impact of oxidative stress on blood plasma in thalassemia, with up-regulation of antioxidant proteins probably reflecting a homeostatic response to these increased stress levels.

Pseudoxanthoma elasticum: oxidative stress and antioxidant diet in a mouse model (Abcc6-/-)

Pseudoxanthoma elasticum (PXE), a multisystem disorder characterized by ectopic mineralization of soft connective tissues, is caused by mutations in the ABCC6 gene. The pathomechanistic details of the mineralization process are largely unknown, but oxidative stress has been suggested to play a role. In this study, we tested Abcc6(-/-) mice, which serve as a model of PXE, for markers of the oxidative stress in the liver and serum. The total antioxidant capacity as well as markers of protein oxidation and lipid peroxidation suggested the presence of chronic oxidative stress. Feeding these mice for 5 months with a diet supplemented with antioxidants (vitamins C and E, selenium, and N-acetylcysteine) countered the oxidative stress but did not modify the ectopic mineralization process. These results suggest that the Abcc6(-/-) mice suffer from chronic oxidative stress but this does not contribute to connective tissue mineralization, the hallmark of PXE.

Hemostatic and thrombotic markers in patients with hemoglobin E/beta-thalassemia disease

Increased frequency of thrombosis has been observed in patients with hemoglobin E/beta-thalassemia (Hb E/beta-thal) disease, particularly those who have previously been splenectomized. We compared various hemostatic and thrombotic markers in blood from 15 Hb E/beta-thal patients who were not splenectomized (NS), 15 who had been splenectomized (S), and 15 normal controls (NC). Levels of plasma thrombin-antithrombin, beta2 thromboglobulin, C-reactive protein, tissue plasminogen activator antigen were significantly higher in the S group than in either the NS or the NC groups, and levels of prothrombin fragment 1.2 were significantly higher in the S than in the NC group. Levels of plasminogen activator inhibitor-1 antigen were significantly higher in the S than in the NS group. Levels of protein C, protein S, antithrombin, and fibrinogen were significantly lower in the S and NS groups than in the NC group. Plasma lipoprotein(a) levels in the S and NS groups were not statistically different from NC. Our findings indicated that there is evidence of chronic low-grade coagulation and platelet activation, chronic low-grade inflammation, endothelial cell injury, impaired fibrinolysis, and decreased naturally occurring anticoagulants in splenectomized Hb E/beta-thal patients. These changes may account for the increased risk of thrombosis in these patients.

Elastic Properties of the Ascending Aorta in Patients with ?-Thalassemia Major

BACKGROUND

Beta-thalassemia major (beta-TM) is a congenital hemolytic disorder characterized by impaired left ventricular and endothelial function. However, elastic properties of the aorta have not been sufficiently investigated in patients with beta-TM. We investigated whether beta-TM is related to impaired ascending aortic elastic properties.

METHODS

We studied 36 patients with beta-TM (age: 15.8 +/- 2.6 years) and 30 age- and sex-matched control subjects by echocardiography. Aortic elastic indexes, aortic strain (%), distensibility (cm(2) dyn(-1) 10(-3)), and stiffness index were calculated from the echocardiographically derived thoracic aortic diameters (mm/m(2)), and the measurement of pulse pressure obtained by cuff sphygmomanometry.

RESULTS

Patients versus control subjects had increased aortic diameters (P < 0.001), lower mean aortic strain (9 +/- 3.6 vs. 14.9 +/- 3.2, P < 0.001) and distensibility (0.6 +/- 0.36 vs. 0.8 +/- 0.2, P < 0.012), and higher mean stiffness index (5.3 +/- 2.4 vs. 2.8 +/- 0.6, P < 0.001). Aortic elastic indexes were significantly associated with ferritin level, while stiffness index was significantly related to platelet count.

CONCLUSION

Elastic properties of ascending aorta are impaired in patients with beta-TM. Impaired functions of aorta may lead to deterioration of left ventricular function.

Lipid profile in ?-thalassemia intermedia patients: correlation with erythroid bone marrow activity

Lipid abnormalities, including low levels of all fractions of serum lipids, have been repeatedly reported in all phenotypes of beta-thalassemia. Unexpectedly, in more recent studies, the concentration of total cholesterol (TC) and high- and/or low-density lipoprotein cholesterol (HDL-C and LDL-C) has been found in beta-thalassemia intermedia (TI) patients even lower than in thalassemia major, without a clear explanation of pathophysiology of these findings. This lack of information prompted us to evaluate the plasma lipids and lipoproteins pattern in the TI patients followed in our department; the data were compared with those found in hereditary spherocytosis patients. Furthermore, in both groups of patients, the erythroid bone marrow activity was evaluated, utilizing the level of soluble transferrin receptors (sTfR) in the plasma. Both groups of patients showed similar lipid abnormalities (low-TC, HDL-C and LDL-C) and the same increase of sTfR, with significantly lower hemoglobin levels in TI patients. Data analysis of our study shows that the lipid profile in TI patients is not influenced by age, sex, liver injury, hemoglobin or ferritin levels; the higher erythroid bone marrow activity with the enhanced cholesterol consumption could be the dominant mechanism implicated in the lipid abnormalities of TI patients.

Oxidative status and serum PON1 activity in beta-thalassemia minor

OBJECTIVES

Paraoxonase-1 (PON1) deficiency is related to increased susceptibility to low density lipoprotein oxidation and development of atherosclerosis. The aim of this study was to investigate paraoxonase and arylesterase activities along with oxidative status parameters, and to find out if there is any increased susceptibility to atherogenesis, which might be reflected with increased oxidative stress and decreased serum PON1 activity in beta-thalassemia minor (BTM) subjects.

DESIGN AND METHODS

Thirty-two subjects with BTM and 28 healthy subjects as control were enrolled in the study. Serum paraoxonase and arylesterase activities, lipid hydroperoxide (LOOH) levels, total antioxidant capacity (TAC), total oxidant status (TOS) and oxidative stress index (OSI) were determined.

RESULTS

Serum TAC, paraoxonase and arylesterase activities were significantly lower in BTM subjects than controls (for all p<0.001), while TOS, LOOH levels and OSI were significantly higher (p<0.001, p<0.05 and p<0.001; respectively). In BTM subjects, OSI, TOS, LOOH levels and TAC were significantly correlated with serum paraoxonase (r=-0.245, p<0.05; r=-0.231, p<0.05; r=-0.264, p<0.05 and, r=0.342, p<0.05, respectively) and arylesterase activities (r=-0.332, p<0.05, r=-0.308, p<0.05; r=-0.320, p<0.05 and r=0.443, p<0.05). Additionally, hemoglobin level was also correlated with serum paraoxonase (r=0.501, p<0.001) and arylesterase activities (r=0.501, p<0.001), TAC (r=0.402, p<0.05), TOS (r=-0.274, p<0.05) and OSI (r=-0.352, p<0.05).

CONCLUSIONS

Oxidative stress is increased, while serum PON1 activity is decreased in BTM subjects. Decrease in PON1 activity seems to be associated with both the degree of oxidative stress and anemia. BTM subjects may be more prone to development of atherogenesis due to low serum PON1 activity.

Carotid intima-media thickness is increased and related to arterial stiffening in patients with beta-thalassaemia major

An increased iron store has been linked to the risk of atherosclerosis. The carotid intima-media thickness (IMT), stiffness index, Young's elastic modulus (YEM), and augmentation index were determined in 20 patients with beta-thalassaemia major. Compared with controls, patients had greater IMT (P < 0.001), YEM (P = 0.005), and stiffness (P = 0.009) and augmentation (P = 0.03) indices. The odds ratio for increased IMT in patients was 39. Carotid IMT correlated with YEM (P = 0.036), stiffness index (P = 0.036) and augmentation index (P = 0.006). Multivariate analysis identified patient status (P < 0.001) as the only significant determinant of IMT. These findings suggest the possibility of premature atherosclerosis in beta-thalassaemia major patients.

Oxidative stress and inflammation in iron-overloaded patients with beta-thalassaemia or sickle cell disease

Blood transfusion therapy is life-saving for patients with beta-thalassaemia and sickle cell disease (SCD), but often results in severe iron overload. This pilot study examined whether the biomarkers of tissue injury or inflammation differ in these two diseases. Plasma malondialdehyde (MDA) was significantly increased 1.8-fold in thalassaemia relative to control patients. In contrast, MDA in SCD was not significantly different from controls. In multivariate analysis, the strongest predictors of elevated MDA were liver iron concentration (P < 0.001) and specific diagnosis (P = 0.019). A significant 2-fold elevation of non-transferrin bound iron (NTBI) was observed in thalassaemia relative to SCD. NTBI was not a significant predictor of high MDA in multivariate analysis. SCD patients showed a significant 2.2-fold elevation of the inflammatory marker interleukin (IL)-6 relative to controls, and a 3.6- and 1.7-fold increase in IL-5 and IL-10 relative to thalassaemia. Although alpha-tocopherol was significantly decreased by at least 32% in both thalassaemia and SCD, indicating ongoing oxidant stress and antioxidant consumption, gamma-tocopherol, a nitric oxide-selective antioxidant, was increased 36% in SCD relative to thalassaemia. These results demonstrate that thalassaemia patients have increased MDA and circulating NTBI relative to SCD patients and lower levels of some cytokines and gamma-tocopherol. This supports the hypothesis that the biology of SCD may show increased inflammation and increased levels of protective antioxidants compared with thalassaemia.

Lipid fluidity at different regions in LDL and HDL of β-thalassemia/Hb E patients

Atherosclerosis-related vascular complications in beta-thalassemia/hemoglobin E (beta-thal/Hb E) patients may result from iron induced oxidation of lipoproteins. To identify the specific site of oxidative damage, changes in lipid fluidity at different regions in LDL and HDL particle were investigated using two fluorescence probes and two ESR spin probes. The magnitude of increased lipid fluidity in thalassemic lipoproteins was dependent on the location of the probes. In hydrophobic region, the rotational correlation times for 16-doxyl stearic acid and DPH anisotropy were markedly changed in LDL and HDL of the patients. In the surface region, there was only a slight change in the order parameter (S) for 5-doxyl stearic acid and TMA-DPH anisotropy. Lipid fluidity at the core of LDL and HDL showed good correlation with oxidative stress markers, the ratio of CL/CO, and the level of alpha-tocopherol, suggesting that hydrophobic region of thalassemic lipoprotein was a target site for oxidative damage.

Stiffness of the abdominal aorta in beta-thalassemia major patients related with body iron load

OBJECTIVES

Increased iron stores have been implicated in the association with increased risk of cardiovascular events. We evaluated whether the abdominal aortic stiffness was altered in the patients with beta-thalassemia major in relation with body iron load.

METHODS

Sixty-two (32 males and 30 females) beta-thalassemia major patients aged 16.47 +/- 4.8 years were enrolled into the study. Healthy 52 subjects matched for age and sex were recruited as controls. In all subjects, hemoglobin, fasting glucose, cholesterol, high-density lipoprotein-cholesterol, and low-density lipoprotein-cholesterol levels were measured. The average serum ferritin level and liver iron concentration (LIC) were assessed in thalassemia patients. Left ventricular function and mass were evaluated echocardiographically and aortic strain (S), pressure strain elastic modulus (Ep), and normalized Ep (Ep*), aortic distensibility (DIS), and beta stiffness index (beta index) were calculated in all subjects.

RESULTS

There was no statistically significant difference between the study and control groups in sex, mean age, body mass index, heart rate, and systolic blood pressure (P > 0.05). However, pulse pressure and left ventricular mass index (LVMI) were found higher in thalassemia major patients compared with the control group. In beta-thalassemia major patients S (0.21 +/- 0.027 vs. 0.26 +/- 0.017, P < 0.0001) and DIS (1.07 +/- 0.25 vs. 1.56 +/- 0.37, P < 0.0001) were significantly lower compared with the control group. However, Ep (196.9 +/- 44.86 vs. 134.20 +/- 29.10, P < 0.0001), Ep* (3.26 +/- 0.98 vs. 2.04 +/- 0.60, P < 0.0001), and beta index (2.44 +/- 0.58 vs. 1.61 +/- 0.37, P < 0.0001) were significantly higher in beta-thalassemia patients than controls. There was a statistically significant negative correlation between LIC and S, DIS. There was also negative correlation between LVMI and S. However, there was a statistically significant positive correlation between LIC and Ep, Ep*.

CONCLUSIONS

Increased abdominal aortic stiffness was detected in beta-thalassemia major patients and this increase in arterial stiffness correlated with LIC and LVMI.

Identification of mildly oxidized low-density lipoprotein (electronegative LDL) and its auto-antibodies IgG in children and adolescents hypercholesterolemic offsprings

BACKGROUND

Oxidative modification of low-density lipoproteins (LDL) is an essential step in atherogenesis, generating minimally oxidized LDL, also called electronegative LDL [LDL(-)], which has chemotactic, cytotoxic and immunogenic properties.

METHODS AND RESULTS

Serum LDL(-) and anti-LDL(-) auto-antibodies (IgG) were evaluated in 28 children and adolescents with familial hypercholesterolemia (FH) antecedents, with or without early coronary artery disease in first-degree relatives (eCAD), hypercholesterolemic (hc) or normocholesterolemic (nc) versus a control group of normocholesterolemic children without pathologic antecedents (C). ELISA method was used for detection of LDL(-) and anti-LDL(-) IgG. LDL(-) serum levels did not differ among the four groups (FH-eCAD-hc 41.4 +/- 24.9 microg/dl; FH-hc 38.3 +/- 11.2 microg/dl; FH-nc 47.3 +/- 17.0 microg/dl and C 44.2 +/- 28.8 microg/dl, p = 0.659). However, IgG anti-LDL(-) auto-antibodies were significantly higher in the control group in comparison to the FH groups with or without eCAD, independent of hypercholesterolemia or normocholesterolemia (FH-eCAD-hc 0.825 +/- 0.289 microg/dl; FH-hc 0.667 +/- 0.307 microg/dl; FH-nc 0.763 +/- 0.204 microg/dl and C 1.105 +/- 0.233 microg/dl, p = 0.006). When the auto-antibodies of groups with FH, with or without eCAD and with or without hypercholesterolemia were compared, no differences were found (p = 0.509).

CONCLUSION

These results showed that FH and/or eCAD children and adolescents have lower titers of auto-antibodies anti-LDL(-) than children from normal families, independent of serum LDL-cholesterol or serum LDL(-).

Vitamin E inhibits hemolysis induced by hemin as a membrane stabilizer

Hemin is a potential cytolytic agent. To test the effect of vitamin E on hemin-mediated permeability in cell membranes, sheep erythrocytes were chosen as an appropriate model to study hemolysis induced by hemin. Hemin-induced hemolysis but did not elicit lipid peroxidation in sheep erythrocytes. Vitamin E was effective in inhibiting hemin-mediated hemolysis. Both chromanol ring and the isoprenoid side chain of tocopherols were essential for inhibition of hemin-induced hemolysis. There was a strong correlation between the inhibitory effects of tocopherols on hemin-induced erythrocyte hemolysis and their effects on fluorescence anisotropy of cell membranes. Our results suggested that, in contrast to its antioxidant activity, vitamin E inhibits hemolysis induced by hemin as a membrane stabilizing agent.

Oxidative stress in fibroblasts from patients with pseudoxanthoma elasticum: possible role in the pathogenesis of clinical manifestations

Pseudoxanthoma elasticum (PXE) is a genetic disease characterized by calcification and fragmentation of elastic fibres of the skin, cardiovascular system and eye, caused by mutations of the ABCC6 gene, which encodes the membrane transporter MRP6. The pathogenesis of the lesions is unknown. Based on studies of similar clinical and histopathological damage present in haemolytic disorders, our working hypothesis is that PXE lesions may result from chronic oxidative stress occurring in PXE cells as a consequence of MRP6 deficiency. Our results show that PXE fibroblasts suffer from mild chronic oxidative stress due to the imbalance between production and degradation of oxidant species. The findings also show that this imbalance results, at least in part, from the loss of mitochondrial membrane potential (DeltaPsi(m)) with overproduction of H2O2. Whether mitochondrial dysfunction is the main factor responsible for the oxidative stress in PXE cells remains to be elucidated. However, mild chronic generalized oxidative stress could explain the great majority of structural and biochemical alterations already reported in PXE.

Effects of malondialdehyde content in low density lipoproteins on platelet adhesion

Platelets play a key role in thrombotic vascular occlusion at the side of an atherosclerotic plaque. Malondialdehyde (MDA) derivatives are components of oxidized LDL. Recent studies suggest enhanced adhesion of platelets on oxidized LDL, but evidence of MDA-modified LDL contribution to enhanced platelet adhesion is missing. The aim of this study was to investigate platelet adhesion on LDLs with various content of MDA and to analyze its physiological relevance. LDLs were isolated by hydroxyapatite chromatography then analyzed. MDA, vitamin E and vitamin A content was estimated by HPLC methods and adhesion of platelets on modified LDLs was assessed. Both MDA and hypochlorite reactions induced an increase of both malondialdehyde content and negative charge in LDLs preparations. In LDLs of iron-overloaded patients both MDA content and negative charge was also significantly increased. The analysis of data showed that enhanced negative charge of LDLs had only negligible influence on platelet adhesion. The binding of platelets on LDL particles modified by MDA resulted in an S-shape curve and was substantially enhanced by high levels of MDA in LDL preparations. Malondialdehyde content both in hypochlorite modified LDLs and in LDLs of iron-overloaded patient matched the lower part of the binding curve. The platelet adhesion on circulating LDLs modified in in vivo conditions of oxidation stress in blood of iron-overloaded patients depends with considerable certainty preferably on non-MDA derived changes in derivatized LDLs. On the other hand, oxidized LDLs in atherosclerotic lesions can be much more extensively modified by MDA resulting in surfaces with enhanced affinity to adhering platelets. Such LDLs may be accessible to platelets, due to endothelial denudation or plaque rupture.

Impact of excess weight and estrogen receptor gene polymorphisms on clinical course of homozygous beta thalassemia

In homozygous beta thalassemic patients we examined the role played by the interaction of ER gene polymorphisms with adverse environmental factors. A total of 108 homozygous beta thalassemic patients, 60 prepubertal mean age 9,5 +/- 3,7 years (27 M, 33 F) and 48 pubertal mean age 22,2 +/- 5,4 years (21 M, 27 F), regularly treated with red cell transfusion and iron chelation therapy were segregated on the basis of their XbaI and PvuII ER gene polymorphisms. Body mass index (BMI), lipidic pattern and blood pressure values were evaluated in each group. No significant differences were observed between patients segregated by their PvuII ER genotypes. Prepubertal and pubertal patients of both sexes lacking XbaI site showed BMI, HDL, LDL cholesterol significantly different than the other patients. In addition, triglyceride levels and blood pressure values were significantly higher in pubertal patients of both sexes lacking XbaI site than in other patients. ER XbaI polymorphism appear to influence nutritional factors, metabolic status and blood pressure and could be considered additional risk factors for later cardiac involvement in beta thalassemic patients.

Endothelial dysfunction and inflammatory process in transfusion-dependent patients with beta-thalassemia major

BACKGROUND

Beta-thalassemia major is associated with increased cardiovascular risk, although the underlying mechanisms remain unclear. We examined endothelial function and serum levels of inflammatory mediators in transfusion-dependent patients with beta-thalassemia major.

METHODS

The study population consisted of 67 patients with homozygous beta-thalassemia major, (aged 24.6+/-0.7 years) and 71 healthy age and sex matched controls. Forearm blood flow was measured with gauge-strain plethysmography. Forearm vasodilatory response to reactive hyperemia (RH%) or to nitrate (NTG%) was expressed as the percentage change of forearm blood flow from baseline to the maximum flow during reactive hyperemia or sublingual nitroglycerin, respectively. Serum levels of interleukin 6 (IL-6), soluble vascular cell adhesion molecule (sVCAM-1) and soluble intercellular adhesion molecule (sICAM-1) were determined with ELISA.

RESULTS

Patients had significantly lower levels of total cholesterol (125+/-4.5 vs. 207+/-7 mg/ml, p<0.01), ApoA1 (120+/-3 vs. 129+/-5 mg/ml, p<0.05), ApoB (60.5+/-2 vs. 95+/-4 mg/ml, p<0.01), ApoE (3+/-2 vs. 4+/-0.2 mg/ml, p<0.01) and Lp(a) (7.9+/-1.3 vs. 14.5+/-3.2 mg/ml, p<0.01) than controls. IL-6 levels were significantly higher in patients (3.03+/-0.31 pg/ml) than controls (1.15+/-0.15 pg/ml, p<0.01). Similarly, sVCAM-1 and sICAM-1 levels were significantly higher in patients (513+/-31 and 368+/-25.5 ng/ml, respectively) than controls (333+/-13.8 and 272+/-14.05 ng/ml, respectively, p<0.01 for both). Maximum hyperemic forearm blood flow and RH% were lower in patients (7.1+/-0.3 ml/100 ml tissue/min and 49+/-2.8%, respectively) than controls (8.26+/-0.32 ml/100 ml tissue/min and 86.3+/-5.57%, respectively, p<0.01 for both).

CONCLUSIONS

Beta-thalassemia major is associated with impaired endothelial function and increased levels of IL-6, sVCAM-1 and sICAM-1, suggesting a potential role of inflammation and endothelial dysfunction in the complications of the disease.

Generation of free radical by interaction of iron with thiols in human plasma and its possible significance

It has been reported that iron can generate reactive oxygen species (ROS) with thiols. In this study, we examined the interaction of iron with thiols in plasma and the generation of ROS. In human plasma, unlike with Fe(3+), treatment with Fe(2+) increased lucigenin-enhanced chemiluminescence in a concentration-dependent manner, and this was inhibited by superoxide dismutase. Boiling of plasma did not affect chemiluminescence generation induced by Fe(2+). Thiol depletion in plasma by pretreatment with N-ethylmaleimide (NEM) decreased chemiluminescence significantly. Consistent with these findings, albumin, the major thiol contributor in plasma, also generated ROS with Fe(2+). Treatment with Fe(2+) resulted in significant reduction of oxygen radical absorbance capacity (ORAC value) in plasma followed by an increase in low-density lipoprotein (LDL) oxidation. These results suggest that generation of ROS by nonenzymatic reaction of Fe(2+) with plasma thiols could lead to reduction of total antioxidant capacity in plasma, thereby enhancing susceptibility of plasma LDL to oxidation under iron overload conditions.

Antioxidant deficit and enhanced susceptibility to oxidative damage in individuals with different forms ofα-thalassaemia

alpha-Thalassaemia is a common red cell disorder in Taiwan, affecting 6-8% of Taiwanese. Previous studies have shown that reactive oxygen species are generated in increased amounts in thalassaemic red cells. This implies the possible alteration of redox status in thalassaemic patients, which may adversely affect their health. In the present study, the redox status of patients with alpha-thalassaemia trait and haemoglobin H (Hb H) disease was investigated. Lipid peroxidation, as measured by the level of plasma thiobarbituric acid reactive substances (TBARS), was increased in alpha-thalassaemic patients, with the highest level of TBARS in Hb H disease patient. The plasma levels of vitamin A, C, and E were significantly lower in alpha-thalassaemic patients than in controls. The overall antioxidant capacity in plasma was inversely correlated with the severity of alpha-globin gene defect: the more severe the form of alpha-thalassaemia, the lower the overall antioxidant capacity in plasma. Erythrocytes isolated from alpha-thalassaemia patients had lower levels of vitamin E, glutathione, catalase and superoxide dismutase. In addition, these alpha-thalassaemic red cells were more susceptible to hydrogen peroxide-induced lipid peroxidation and decrease in deformability. All these data suggest that the alpha-thalassaemic patients suffer from increased oxidative stress and antioxidant deficit, which may complicate the pathophysiology of alpha-thalassaemia.

Oxidized low-density lipoprotein, iron stores, and haptoglobin polymorphism

BACKGROUND

In vitro experimental studies demonstrated that iron promotes free radical-induced low-density lipoprotein (LDL) oxidation.

OBJECTIVE

To test the hypothesis that circulating oxidized LDL (oxLDL) levels might be associated with body iron stores (serum ferritin) and iron-related genetic markers (hemochromatosis gene C282Y mutation, haptoglobin polymorphism).

METHODS

We investigated 381 (176 males, 205 females, age 45 +/- 6 years) healthy Caucasians. Serum oxLDL, assayed by a mAb-4E6-based enzyme-linked immunosorbent assay (ELISA), was expressed as oxLDL/LDL ratio to adjust for serum LDL-cholesterol concentration. Hemochromatosis gene C282Y mutation analysis was performed by a Taqman-based polymerase chain reaction (PCR) assay. Haptoglobin (Hp) phenotypes (Hp 1-1, Hp 2-1, Hp 2-2) were determined by starch gel electrophoresis.

RESULTS

In stepwise multivariate regression analysis, gender (P < 0.0001), current smoking (P < 0.0001), HDL-cholesterol (P = 0.0001), ferritin (P = 0.0051), body mass index (BMI) (P = 0.0063), and Hp phenotype (P = 0.0331) independently predicted oxLDL/LDL ratio in the total group. In men, smoking (P < 0.0001), ferritin (P = 0.0052), Hp phenotype (P = 0.0063), and HDL-cholesterol (P = 0.0127) were independent determinants of oxLDL/LDL ratio. In women, only body mass index (P < 0.0001), HDL-cholesterol (P = 0.0005), and smoking (P = 0.0025) were significantly associated with oxLDL/LDL ratio. The C282Y mutation (wild-type versus C282Y heterozygotes) was not associated with oxLDL/LDL ratio in both sexes.

CONCLUSION

Serum ferritin concentration and Hp polymorphism are independently associated with circulating oxLDL levels in males.

Autoantibodies against oxidized low-density lipoprotein (ox-LDL) and LDL oxidation status

Oxidized low-density lipoproteins (ox-LDLs) and their autoantibodies (OLAB) are involved in the development of atherosclerosis in animal models, but their role in humans is still not clear. For this reason we studied 54 patients with β-thalassemia major (TM), as a model of chronically low circulating LDLs with a high level of oxidation; 44 patients with primary hypercholesterolemia, as model of chronically high circulating LDLs; 24 type 2 diabetic mellitus patients (T2DM) before and after 3 months of atorvastatin treatment (20 mg/day), as a model of acute changes in circulating LDLs; and 41 normolipidemic subjects as a control group. ox-LDLs were measured by the determination of baseline diene concentration in the plasma LDL lipidic fraction after 12 hours fasting and were expressed as the amount of conjugated dienes/liter (BDC/l) or BDC/LDL-cholesterol (LDL-C), which indicate respectively LDL oxidation degree and status. OLABwere determined using an enzyme immunoassay and related to LDL oxidation degree (BDC/l). In TM, BDC/l was lower, while BDC/LDL-C was significantly higher, compared to both hypercholesterolemia and normolipidemic subjects. Patients with hypercholesterolemia had higher BDC/l, but lower BDC/LDL-C and OLAB/BDC-l, than normolipidemic subjects. In T2DM patients at diet, BDC/LDL-C and OLAB/BDC-l were lower than in normolipidemic subjects. After 3 months of atorvastatin treatment, BDC/LDL-C and OLAB/BDC-l ratios increased. When all patients were evaluated together, a significant inverse correlation was evident between OLABand either LDL or BDC/l. Our findings suggest that a relationship between OLABtiter and oxidation indices (BDC/l and BDC/LDL-C) does exist and we may speculate that an increase in OLAB/BDC-l ratio might be protective against the risk of atherosclerosis.

Oxidant, antioxidant status and metabolic data in patients with beta-thalassemia

BACKGROUND

In beta-thalassemia major impaired biosynthesis of beta globin leads to accumulation of unpaired alpha globin chain. An iron overload, usually observed, generates oxygen-free radicals and peroxidative tissue injury.

AIM

To investigate hematological parameters, oxidative stress and the antioxidant capacity in beta-thalassemia patients compared to control subjects in order to determine their impact in several organs functions.

METHODS

This study was conducted on 56 beta-thalassemia major patients compared to 51 healthy subjects. We determined metabolic parameters (glycaemia, lipid parameters, electrolytes, iron indices, hepatic, renal and heart functions tests), plasmatic thiobarbituric acid reactive substances (TBARS), plasmatic peroxyl radical trapping potential (TRAP), plasmatic superoxide dismutase (SOD), erythrocyte gluthathione peroxidase (GPX), plasmatic vitamin E, vitamin A and trace elements.

RESULTS

Except triglycerides, lipid fractions were significantly decreased in beta-thalassemia compared to controls. Serum ferritin, iron, TBARS concentrations, SOD and GPX activities were significantly increased. But TRAP, vitamin E and zinc concentrations were significantly decreased.

CONCLUSION

Our findings confirm the peroxidative status generated by iron overload in beta-thalassemia major patients and highlight the rapid formation of marked amounts of TBARS and the increase of SOD and GPX activity. Our study suggested that in beta-thalassemia the first organ impaired is the liver.

Oxidized LDL antibodies (OLAB) in patients with beta-thalassemia major

Thalassemic (TM) patients are subjected to peroxidative tissue injury because of continuous blood transfusions. It has been documented that circulating LDL from TM patients show marked oxidative modification, that could represent an event leading to atherogenesis. We investigated in 75 beta-TM patients the levels of oxidized LDL antibody (OLAB) to asses their correlation with total cholesterol, LDL and HDL cholesterol, triglycerides Apo A-1 and Apo B. OLAB/mg chol-LDL is greater in TM patients than healthy controls (p<0.001). No correlation was found between OLAB and age, sex of patients, mean blood consumption, mean serum ferritin, mean transaminases, PT, PTT, and fibrinogen. A significant positive correlation was found between OLAB and triglycerides in TM patients (p<0.001). Also a significant correlation was found between OLAB/mg chol-LDL and level of triglycerides in TM patients, but not with total cholesterol, LDL and HDL chols, Apo A-1 and Apo B. On the contrary in the healthy controls this correlation between OLAB and OLAB/mg chol-LDL versus triglycerides was negative and not significant. High levels of OLAB/mg chol-LDL in patients with beta-thalassemia, in absence of evident signs of atherosclerosis, suggest some regulatory mechanisms on the lipid peroxidation which modulate the deposition of ox-LDL in the macrophages and support the hypothesis that both serum iron and triglycerides are involved in the pathogenesis of LDL oxidation.

Hypocholesterolemia in children and adolescents with beta-thalassemia intermedia

OBJECTIVES

To conduct a prospective study to evaluate the lipid profile in children and adolescents with beta-thalassemia intermedia and major, and to examine the contribution of different factors to hypocholesterolemia observed in these patients.

STUDY DESIGN

Demographic, clinical, and laboratory data were prospectively obtained from patients with beta-thalassemia intermedia (n = 9) and major (n = 47). Lipid profiles were also determined in a control group of healthy children (n = 18). Lipid values of beta-thalassemics and controls were compared and the relationships between lipid levels and different covariates were determined.

RESULTS

beta-thalassemia intermedia patients had significantly lower total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) compared with beta-thalassemia major and controls (P <.001). With regression analysis, serum lipid levels (TC, HDL-C, and triglycerides) correlated with diagnosis (beta-thalassemia major or intermedia) but not with age, sex, hemoglobin, or ferritin. LDL-C was influenced by both diagnosis and ferritin levels.

CONCLUSIONS

Children and adolescents with beta-thalassemia intermedia have significantly lower cholesterol levels than patients with beta-thalassemia major. This is related to their disorder and not influenced by age, sex, hemoglobin, or ferritin levels. In these patients, needless investigations for hypolipidemia should be avoided.

Oral supplements of vitamin E improve measures of oxidative stress in plasma and reduce oxidative damage to LDL and erythrocytes in beta-thalassemia intermedia patients

Fifteen beta-thalassemia intermedia patients, not requiring chronic transfusional therapy, were monitored in order to check their antioxidant status, and the lipid oxidation products in plasma, LDL, and erythrocytes before and during a 9-month oral treatment with 600 mg/day vitamin E. The low level of vitamin E, and high level of malondialdehyde in plasma clearly tended to normalize after three months (P < .001), and were quite similar to control after six months. The abnormally low level of vitamin E in LDL and the four times higher than control basal level of conjugated dienes (LDL-CD), were not modified after three months of treatment. Significant changes of LDL-VE (P < .05) and of the basal LDL-CD (P < .001) were evident after six months. LDL-VE was within the normal range after nine months, whereas LDL-CD still appeared twice as higher than control. Plasma vitamin A, ascorbate, beta-carotene, and lycopene increased markedly at the end of the trial (P < .005). The level of vitamin E in red blood cells was normalized after six months of supplementation. A decrease of the baseline value of conjugated dienes was observed after nine months, although it remained 1.4-fold higher than control. The RBC count and hematocrit appeared higher at the end of the trial (P < .05 and P < .001, respectively). The hemoglobin value did not show variations. A shift to normal of the resistance of erythrocytes to osmotic lysis was observed. Our findings provide evidence that an oral treatment with vitamin E improves the antioxidant/oxidant balance in plasma, LDL particles, and red blood cells, and counteracts lipid peroxidation processes in beta-thalassemia intermedia patients.

Clinical use of topoisomerase I inhibitors in anticancer treatment

The camptothecin analogs topotecan and irinotecan have shown to be among the most effective anticancer agents and, as S-phase specific agents, their antitumor effect is maximized when they are administered in protracted schedules. The documented activity as single agents in many adult and pediatric malignancies has been followed by their use in combination with other anticancer agents. These studies have shown promising results, and have placed topotecan and irinotecan in the first line treatment for some malignancies. However, studies to better determine the optimal schedules and sequence of combinations are needed.

Clinical and hematologic aspects of hemoglobin E beta-thalassemia

Hemoglobin E beta-thalassemia is an important cause of childhood chronic disease in Southeast Asia. It is characterized by the presence of hemoglobin E and F, and the amount of hemoglobin E ranges from 35% to 75%. The patients are generally classified as having thalassemia intermedia because they have inherited a beta-thalassemia allele and hemoglobin E, which acts as a mild beta+-thalassemia. However, a remarkable variability in the clinical expression, ranging from a mild form of thalassemia intermedia to transfusion-dependent conditions, is observed. Severe hemoglobin E beta-thalassemia may have clinical features of thalassemia major. Phenotypes of thalassemia major can be predicted from the early onset of clinical symptoms and the requirement of regular blood transfusion from infancy for survival. Coinheritance of alpha-thalassemia alleviated the severity of beta-thalassemia disease in patients with at least one allele of mild beta-thalassemia genotype.

Low-density lipoprotein susceptibility to oxidation and cytotoxicity to endothelium in sickle cell anemia

Patients with sickle-cell anemia exhibit pro-oxidative metabolic perturbations. We hypothesize that because of chronic oxidative stress, plasma low-density lipoprotein (LDL) from patients with sickle-cell anemia is more susceptible to oxidation. To test this hypothesis, LDL susceptibility to copper-mediated oxidation was measured in 24 patients with sickle-cell anemia and 48 control subjects. Sickle-cell LDL was more susceptible to oxidation than control LDL, measured by a 22% shorter mean lag time between LDL exposure to CuSO4 and conjugated diene formation (97 vs 124 minutes; P = .023). LDL vitamin E, iron, heme, and cholesterol ester hydroperoxide (CEOOH) levels were also measured. LDL vitamin E levels were significantly lower in patients with sickle-cell anemia compared with control subjects (1.8 vs 2.9 mol/mol LDL; P = .025), but there was no correlation with lag time. Pro-oxidant heme and iron levels were the same in sickle-cell and control LDL. LDL CEOOHs were not significantly different in sickle and control LDL (3.1 vs 1.2 mmol/mol of LDL unesterified cholesterol, P = .15), but LDL CEOOH levels were inversely correlated with lag times in patients with sickle-cell anemia (r2 = 0.38; P = .018). The cytotoxicity of partially oxidized LDL to porcine aortic endothelial cells was inversely correlated with lag times (r2 = 0.48; P = .001). These preliminary data suggest that increased LDL susceptibility to oxidation could be a marker of oxidant stress and vasculopathy in patients with sickle-cell anemia.