Four new mutations in the erythroid-specific 5-aminolevulinate synthase (ALAS2) gene causing X-linked sideroblastic anemia: increased pyridoxine responsiveness after removal of iron overload by phlebotomy and coinheritance of hereditary hemochromatosis.
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X-linked sideroblastic anemia (XLSA) in four unrelated male probands was caused by missense mutations in the erythroid-specific 5-aminolevulinate synthase gene (ALAS2). All were new mutations: T647C, C1283T, G1395A, and C1406T predicting amino acid substitutions Y199H, R411C, R448Q, and R452C. All probands were clinically pyridoxine-responsive. The mutation Y199H was shown to be the first de novo XLSA mutation and occurred in a gamete of the proband's maternal grandfather. There was a significantly higher frequency of coinheritance of the hereditary hemochromatosis (HH) HFE mutant allele C282Y in 18 unrelated XLSA hemizygotes than found in the normal population, indicating a role for coinheritance of HFE alleles in the expression of this disorder. One proband (Y199H) with severe and early iron loading coinherited HH as a C282Y homozygote. The clinical and hematologic histories of two XLSA probands suggest that iron overload suppresses pyridoxine responsiveness. Notably, reversal of the iron overload in the Y199H proband by phlebotomy resulted in higher hemoglobin concentrations during pyridoxine supplementation. The proband with the R452C mutation was symptom-free on occasional phlebotomy and daily pyridoxine. These studies indicate the value of combined phlebotomy and pyridoxine supplementation in the management of XLSA probands in order to prevent a downward spiral of iron toxicity and refractory anemia. (+info)
Iron depletion by phlebotomy with recombinant erythropoietin prior to allogeneic transplantation to prevent liver toxicity.
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Iron overload may induce liver toxicity after hematopoietic stem cell transplantation (HSCT), but it is not known if iron depletion prior to HSCT can reduce the risk of severe toxicity in this setting. We used subcutaneous recombinant erythropoietin (EPO) (25 UI/kg) three times a week and phlebotomy once a week, to prevent liver toxicity in a patient with advanced acute leukemia and liver disease due to severe iron overload, previous drug toxicity and hepatitis C viral infection. Over the 9 months prior to allogeneic HSCT, 34 phlebotomies were carried out. Serum ferritin dropped from 2964 to 239 microg/l and the ALT dropped to near normal values. At allogeneic HSCT no liver toxicity was observed, suggesting that iron depletion in the pretransplant period may contribute to reducing transplant-related toxicity in selected cases. (+info)
Iron overload in porphyria cutanea tarda.
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BACKGROUND AND OBJECTIVE: Porphyria cutanea tarda (PCT) is a disorder of porphyrin metabolism associated with decreased activity of uroporphyrinogen decarboxylase (URO-D) in the liver. The relevance of iron in the pathogenesis of PCT is well established: iron overload is one of the factors that trigger the clinical manifestations of the disease and iron depletion remains the cornerstone of therapy for PCT. A role for genetic hemochromatosis in the pathogenesis of iron overload in PCT has been hypothesized in the past but only after the recent identification of the genetic defect causing hemochromatosis has the nature of this association been partially elucidated. This review will outline current concepts of the pathophysiology of iron overload in PCT as well as recent contributions to the molecular epidemiology of hemochromatosis defects in PCT. EVIDENCE AND INFORMATION SOURCES: The authors of the present review have a long-standing interest in the pathogenesis, etiology and epidemiology of iron overload syndromes. Evidence from journal articles covered by the Science Citation Index(R) and Medline(R) has been reviewed and collated with personal data and experience. STATE OF THE ART AND PERPECTIVES: Mild to moderate iron overload plays a key role in the pathogenesis of PCT. The recent identification of genetic mutations of the hemochromatosis gene (HFE) in the majority of patients with PCT confirms previous hypotheses on the association between PCT and hemochromatosis, allows a step forward in the understanding of the pathophysiology of the disturbance of iron metabolism in the liver of PCT patients, and provides an easily detectable genetic marker which could have a useful clinical application. Besides the epidemiological relevance of the association between PCT and hemochromatosis, however, it remains to be fully understood how iron overload, and in particular the cellular modifications of the iron status secondary to hemochromatosis mutations, affect the activity of URO-D, and how the altered iron metabolism interacts with the other two common triggers for PCT and etiological agents for the associated liver disease: alcohol and hepatitis viruses. The availability of a genetic marker for hemochromatosis will allow some of these issues to be addressed by studying aspects of porphyrins and iron metabolism in liver samples obtained from patients with PCT, liver disease of different etiology and different HFE genotypes, and by in vitro studies on genotyped cells and tissues. (+info)
Effects of repeated jugular puncture on plasma cortisol concentrations in loose-housed dairy cows.
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In three experiments, the effects of venipuncture on plasma cortisol concentrations were studied in loose-housed dairy cows. In Exp. 1, two blood samples were collected 18 min apart on three alternate days from 20 dairy cows for studying their adrenocortical response to a single venipuncture. To further evaluate the effect of cows anticipating venipuncture, in Exp. 2, 15 dairy cows were sequentially venipunctured once daily on 12 successive days in a randomized order in groups of five, starting 15 min apart. In Exp. 3, 10 primiparous cows were used on three alternate days to study habituation to serial sampling (i.e., collection of five blood samples by venipuncture, 15 min apart). In cows accustomed to handling, jugular puncture did not affect cortisol concentrations in plasma collected 18 min later. Average daily cortisol concentrations varied between 2.07 +/- .38 and 3.81 +/- .56 ng/mL in the first (t = 0) and between 1.43 +/- .15 and 2.61 +/- .72 ng/mL in the second (t = 18) blood samples. Likewise, when cows were sampled sequentially once a day, the order of sampling between and within groups did not influence (P > .05) plasma cortisol concentrations. In contrast, primiparous dairy cows that were less used to being handled showed an average increase in cortisol concentrations when five samples were collected by venipuncture 15 min apart. During successive sampling sessions, however, the cows did not decrease or increase plasma cortisol concentrations in response to repeated serial sampling at the group level (P > .05). Between individuals, the maximum effect of repeated venipuncture on cortisol concentrations (4.5 to 22.6 ng/mL), the time at which the effect reached its maximum (30 to 60 min), and the consistency of the response pattern over successive series varied largely. The results of this study show that in cows that were accustomed to handling and to being restrained, baseline cortisol concentrations can be measured in single blood samples that are collected by jugular puncture within 1 min after first approaching the cow. When successive blood samples need to be collected within 15 to 20 min, jugular puncture may induce an increase in cortisol concentration, which seems to depend on the handling experience of the animals and on individual differences. (+info)
The onset of atherosclerotic lesion formation in hypercholesterolemic rabbits is delayed by iron depletion.
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The theory that iron may play a significant role in atherogenesis by promoting the formation of free radicals is controversial. Previous results using the new technique of nuclear microscopy showed a seven-fold increase in iron concentrations within newly formed atherosclerotic lesions in hypercholesterolemic rabbits compared to healthy artery tissue. In a follow-up time sequence study described here, we show that iron accumulation occurs at the onset of lesion formation. In addition, weekly bleeding decreases the iron uptake into the artery wall and delays the onset of atherogenesis. These results provide direct evidence for a key role of iron in initiating atherogenesis. (+info)
Randomised trial of analgesic effects of sucrose, glucose, and pacifiers in term neonates.
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OBJECTIVES: To assess and compare the analgesic effects of orally administered glucose and sucrose and pacifiers. To determine the synergistic analgesic effect of sucrose and pacifiers. DESIGN: Randomised prospective study with validated behavioural acute pain rating scale. SETTING: Maternity ward. PARTICIPANTS: 150 term newborns undergoing venepuncture randomly assigned to one of six treatment groups: no treatment; placebo (2 ml sterile water); 2 ml 30% glucose; 2 ml 30% sucrose; a pacifier; and 2 ml 30% sucrose followed by a pacifier. RESULTS: Median (interquartile) pain scores during venepuncture were 7 (5-10) for no treatment; 7 (6-10) for placebo (sterile water); 5 (3-7) for 30% glucose; 5 (2-8) for 30% sucrose; 2 (1-4) for pacifier; and 1 (1-2) for 30% sucrose plus pacifier. Mann-Whitney U test P values for comparisons of 30% glucose, 30% sucrose, pacifier, and 30% sucrose plus pacifier versus placebo (sterile water) were 0.005, 0.01, <0.0001, and <0.0001, respectively. Differences between group median pain scores for these comparisons were 2 (95% confidence interval 1 to 4), 2 (0 to 4), 5 (4 to 7), and 6 (5 to 8), respectively. P values for comparisons of 30% glucose, 30% sucrose, and 30% sucrose plus pacifier versus pacifier were 0.0001, 0.001, and 0.06, respectively. Differences between group medians for these comparisons were 3 (2 to 5), 3 (1 to 5), and 1 (0 to 2), respectively. CONCLUSION: The analgesic effects of concentrated sucrose and glucose and pacifiers are clinically apparent in newborns, pacifiers being more effective than sweet solutions. The association of sucrose and pacifier showed a trend towards lower scores compared with pacifiers alone. These simple and safe interventions should be widely used for minor procedures in neonates. (+info)
Markers of thrombin and platelet activity in patients with atrial fibrillation: correlation with stroke among 1531 participants in the stroke prevention in atrial fibrillation III study.
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BACKGROUND AND PURPOSE: Markers of thrombin generation and platelet activation are often elevated in patients with nonvalvular atrial fibrillation, but it is unclear whether such markers usefully predict stroke. Therefore, we undertook the present study to assess the relationship between prothrombin fragment F1.2 (F1.2), beta-thromboglobulin (BTG), fibrinogen, and the factor V Leiden mutation with stroke in atrial fibrillation. METHODS: Specimens were obtained from 1531 participants in the Stroke Prevention in Atrial Fibrillation III study. The results were correlated with patient features, antithrombotic therapy, and subsequent thromboembolism (ischemic stroke and systemic embolism) by multivariate analysis. RESULTS: Increased F1.2 levels were associated with age (P<0.001), female sex (P<0.001), systolic blood pressure (P=0.006), and heart failure (P=0.001). F1.2 were not affected by aspirin use and were not associated with thromboembolism after adjustment for age (P=0. 18). BTG levels were higher with advanced age (P=0.006), coronary artery disease (P=0.05), carotid disease (P=0.005), and heart failure (P<0.001), lower in regular alcohol users (P=0.05), and not significantly associated with thromboembolism. Fibrinogen levels were not significantly related to thromboembolism but were associated with elevated BTG levels (P<0.001). The factor V Leiden mutation was not associated with thromboembolism (relative risk 0.5, 95% CI 0.1 to 3.8). CONCLUSIONS: Elevated F1.2 levels were associated with clinical risk factors for stroke in atrial fibrillation, whereas increased BTG levels were linked to manifestations of atherosclerosis. In this large cohort of patients with atrial fibrillation who were receiving aspirin, F1.2, BTG, fibrinogen, and factor V Leiden were not independent, clinically useful predictors of stroke. (+info)
Early iron reduction programme for thalassaemia patients after bone marrow transplantation.
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Thirty thalassaemia patients received iron reduction starting at around 3 months post transplant. Sixteen received desferrioxamine and nine had phlebotomy, five patients had desferrioxamine followed by phlebotomy. The desferrioxamine group had higher serum ferritin levels at the start of iron reduction as compared to the phlebotomy group (5292 vs 2453 microg/l, P EQ 0.001). After 444 and 407 days of iron reduction, serum ferritins at cessation of iron reduction in both groups was similar (665 vs 588 microg/l). The rate of decline of serum ferritin in both groups was similar. There was no graft rejection during the programme. Early institution of iron reduction in ex-thalassaemia is safe. (+info)