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Biomedical subjects

N F Olivieri

Publications and source records attributed to N F Olivieri.

At least 19 recordsLinked to original sources
PubMed2001

Genetic determinants of jaundice and gallstones in haemoglobin E beta thalassaemia.

Chronic hyperbilirubinaemia, gallstone formation, and gall bladder disease are unusually common in people with haemoglobin E beta thalassaemia in Sri Lanka. To determine whether this has a genetic basis we compared the bilirubin levels and frequency of gallstones in patients with different alleles of the UGT*1 gene. There was a significantly higher bilirubin level in those with the 7/7 genotypes compared with 6/6 and 6/7 genotype (p=0.032 and 0.0015 respectively), who also appeared more prone to gallstone formation. These results suggest that the UGT*1 genotpe is of importance in the genesis of gallstones in this population of patients.

Alleles↗
PubMed2001

Hemoglobin H (Hb H) disease in Canada: molecular diagnosis and review of 116 cases.

Over the past decade, we have characterized at the DNA level a total of 116 hemoglobin H (Hb H) disease patients living in Canada. The majority of patients were of southeast Asian descent (Chinese, Filipino, Laotian, Vietnamese), with a small number being of Mediterranean, Middle Eastern or East Indian background. A total of 15 distinct genotypes were detected, all but one being compound heterozygotes for a two-gene cis deletion and a single-gene deletion (-alpha/-) or a non-deletion mutation of the alpha2-globin gene (alpha(T) alpha/-). Seven different two-gene cis deletions were encountered, along with nine single-gene deletions and point mutations. The wide range of mutations associated with Hb H disease in Canada is a reflection of the population heterogeneity. The diagnosis of Hb H disease at the molecular level is important with respect to genetic counseling and the identification of families at risk for having pregnancies affected with Hb Bart's hydrops fetalis syndrome and/or Hb H disease. Six of the Hb H disease patients in our cohort had spouses who carried single-gene deletions, making these couples at risk for having children with Hb H disease. More important, seven patients had partners who carried two-gene cis deletions. These couples are at reproductive risk for both Hb Bart's hydrops fetalis syndrome and Hb H disease.

Adolescent↗
PubMed2001

Progression of iron overload in sickle cell disease.

The expanding indications for transfusions in patients with sickle cell disease raise the issues of appropriate measurement of body iron burden and optimal timing of iron chelation therapy. In this study, we obtained 42 biopsy specimens from 20 patients with sickle cell disease (mean age, 15.7 years) who received transfusions. In 12 patients whose mean age was 11.3 years at the time of liver biopsy, hepatic iron concentration was measured to provide information about the rate of iron accumulation in sickle cell disease, as well as to guide the initiation of chelating therapy. Mean hepatic iron concentration after an average of 15.4 transfusions administered over 21 months was 9.4 +/- 1.2 mg/g liver, dry weight, which did not correlate significantly with determinations of serum transferrin or ferritin levels. On Initial liver biopsy, hepatic portal fibrosis was noted in 4 of 12 patients. Twenty-nine biopsies in 16 patients were performed after variable periods of treatment with deferoxamine. These 16 patients had received a mean of 38.5 transfusions over 4 years. Hepatic iron was 14.1 +/- 1.9 mg/g of liver, dry weight, Indicating poor control of body iron in many patients. Cirrhosis was reported in one of 29 and portal fibrosis in 10 biopsy specimens. Hepatic iron concentration in patients in whom fibrosis was observed varied from 8.9 to 37.7 mg/g of liver, dry weight. These data show that after 1 to 2 years of conventional transfusions, variable tissue iron concentrations and tissue damage are observed in patients with sickle cell disease. In some patients, iron chelation therapy may not be appropriate after 1 year of transfusions; in others, therapy is clearly indicated by this time to prevent tissue injury. The data also suggest that patients with sickle cell disease develop increased portal fibrosis at the thresholds previously described in young patients with thalassemia (approximately 7 mg/g of liver, dry weight).

Adolescent↗
PubMed2001

Identification of two new alpha-thalassemia mutations in exon 2 of the alpha1-globin gene.

The most common causes of alpha-thalassemia are deletions that remove one or both of the functional alpha-globin genes. In addition, more than 30 different point mutations and small deletions/insertions have been reported for the alpha-globin genes. Here, we describe two new mutations occurring in exon 2 of the alpha1-globin gene. One mutation is an insertion of 21 bp that gives rise to a predicted alpha-globin chain containing a duplication of amino acid residues 93-99. The second mutation is a 33 bp deletion resulting in a predicted alpha-globin chain that is missing amino acid residues 64-74. Neither mutation results in a detectable hemoglobin variant, indicating that the variant alpha-globin chains are highly unstable. Carriers of these mutations have mild microcytosis and the phenotype of alpha+-thalassemia trait.

Base Sequence↗
PubMed2001

Secondary iron overload.

Transfusion therapy for inherited anemias and acquired refractory anemias both improves the quality of life and prolongs survival. A consequence of chronic transfusion therapy is secondary iron overload, which adversely affects the function of the heart, the liver and other organs. This session will review the use of iron chelating agents in the management of transfusion-induced secondary iron overload. In Section I Dr. John Porter describes techniques for the administration of deferoxamine that exploit the pharmacokinetic properties of the drug and minimize potential toxic side effects. The experience with chelation therapy in patients with thalassemia and sickle cell disease will be reviewed and guidelines will be suggested for chelation therapy of chronically transfused adults with refractory anemias. In Section II Dr. Nancy Olivieri examines the clinical consequences of transfusion-induced secondary iron overload and suggests criteria useful in determining the optimal timing of the initiation of chelation therapy. Finally, Dr. Olivieri discusses the clinical trials evaluating orally administered iron chelators.

Anemia, Sickle Cell↗
PubMed2000

Thalassaemia in Sri Lanka: implications for the future health burden of Asian populations. Sri Lanka Thalassaemia Study Group.

BACKGROUND: Thalassaemias pose an increasing problem for the Indian subcontinent and many Asian countries. We analysed the different types of thalassaemia in the Sri Lankan population, surveyed gene frequencies in schoolchildren, and estimated the burden of disease and requirements for its control. METHODS: We analysed blood samples from patients attending clinics in nine hospitals and defined the different types of beta thalassaemia by high-performance liquid chromatography (HPLC) and DNA analysis. The range of mutations was obtained by analysis of beta-globin genes. Capillary blood was obtained from schoolchildren from different parts of the island and analysed by HPLC to provide an approximate assessment of the carrier frequency of beta thalassaemia and haemoglobin E (HbE). To estimate the frequency of alpha thalassaemia the alpha-globin genotypes were also analysed when it was possible. FINDINGS: Blood samples were obtained from 703 patients with beta thalassaemia and from 1600 schoolchildren. The thalassaemia mutations were unevenly spread. Although 23 different beta-thalassaemia mutations were found, three accounted for the thalassaemia phenotype in about 70% of the patients, most whom are homozygotes or compound heterozygotes for IVS1-5 (G-->C) or IVS1-1 (G-->A). The third common mutation, codon 26 (G-->A), which produces HbE, interacts with one or other of these mutations to produce HbE/beta thalassaemia; this comprises 13.0-30.9% of cases in the main centres. Samples from 472 patients were analysed to determine the alpha-globin genotype. Overall, 15.5% patients were carriers for deletion forms of alpha+ thalassaemia. Average gene frequencies showed that there will be more than 2000 patients requiring treatment at any one time, in the future, of whom those with HbE/beta thalassaemia will account for about 40%. INTERPRETATION: In Sri Lanka, interactions of the two common beta-thalassaemia alleles will nearly always result in a transfusion-dependent disorder. However, about 40% of patients will have HbE/beta thalassaemia, which has a variable course. The management of these disorders could require about 5% of the total health budget. We need to learn more about the natural history and appropriate management of HbE/beta thalassaemia if resources are to be used effectively.

Adult↗
PubMed2000

Iron deposition in the anterior pituitary in homozygous beta-thalassemia: MRI evaluation and correlation with gonadal function.

OBJECTIVE: Iron deposition in the anterior pituitary continues to pose a serious problem in older patients with homozygous beta-thalassemia particularly in terms of gonadal function. This study aimed to investigate whether iron loading within the pituitary correlated with endocrine function. PATIENTS: 33 patients above 15 years of age, with transfusion-dependent homozygous beta-thalassemia and iron overload were studied. All had been receiving deferoxamine since 1978. DESIGN AND MEASUREMENTS: The endocrine status of the patients was assessed on clinical examination by an endocrinologist, and by a gonadotropin releasing hormone stimulation test. MRI of the pituitary was carried out for each patient. RESULTS: Anterior pituitary function (GnRH stimulation test) correlated well with MRI results. However, no correlation was found between the MRI measurements, the GnRH stimulation test and the clinical status of the patients, as 28 out of the 33 patients achieved normal puberty. CONCLUSIONS: MRI in conjunction with a GnRH stimulation test may be useful in predicting future impairment of pituitary function; however, further studies are needed to assess the effect of chelation therapy on the iron overload in the gland.

Adolescent↗
PubMed1998

Long-term safety and effectiveness of iron-chelation therapy with deferiprone for thalassemia major.

BACKGROUND: Deferiprone is an orally active iron-chelating agent that is being evaluated as a treatment for iron overload in thalassemia major. Studies in an animal model showed that prolonged treatment is associated with a decline in the effectiveness of deferiprone and exacerbation of hepatic fibrosis. METHODS: Hepatic iron stores were determined yearly by chemical analysis of liver-biopsy specimens, magnetic susceptometry, or both. Three hepatopathologists who were unaware of the patients' clinical status, the time at which the specimens were obtained, and the iron content of the specimens examined 72 biopsy specimens from 19 patients treated with deferiprone for more than one year. For comparison, 48 liver-biopsy specimens obtained from 20 patients treated with parenteral deferoxamine for more than one year were similarly reviewed. RESULTS: Of the 19 patients treated with deferiprone, 18 had received the drug continuously for a mean (+/-SE) of 4.6+/-0.3 years. At the final analysis, 7 of the 18 had hepatic iron concentrations of at least 80 micromol per gram of liver, wet weight (the value above which there is an increased risk of cardiac disease and early death in patients with thalassemia major). Of 19 patients in whom multiple biopsies were performed over a period of more than one year, 14 could be evaluated for progression of hepatic fibrosis; of the 20 deferoxamine-treated patients, 12 could be evaluated for progression. Five deferiprone-treated patients had progression of fibrosis, as compared with none of those given deferoxamine (P=0.04). By the life-table method, we estimated that the median time to progression of fibrosis was 3.2 years in deferiprone-treated patients. After adjustment for the initial hepatic iron concentration, the estimated odds of progression of fibrosis increased by a factor of 5.8 (95 percent confidence interval, 1.1 to 29.6) with each additional year of deferiprone treatment. CONCLUSIONS: Deferiprone does not adequately control body iron burden in patients with thalassemia and may worsen hepatic fibrosis.

Adolescent↗
PubMed1998

Elimination of transfusions through induction of fetal hemoglobin synthesis in Cooley's anemia.

Pharmacological stimulation of fetal hemoglobin production is of considerable interest as an alternative approach to therapy for Cooley's anemia. While intravenous compounds have been effective in inducing short-term increases in fetal hemoglobin in a few patients, long-term elimination of transfusion requirement has not been reported. In patients with Cooley's anemia, treatment with oral sodium phenylbutyrate alone, sodium phenylbytyrate combined with hydroxyurea, and hydroxyurea alone, has augmented fetal hemoglobin production and increased total hemoglobin concentration as much as 5 g/dl over baseline eliminating transfusion requirement in two patients. Parallel declines in circulating nucleated red cell count, and concentrations of serum transform receptor and erythropoietin, are consistent with more effective erythropoiesis. Over extended periods of treatment, no induction of other fetal proteins and no adverse effects were observed. Particular disease mutations and other genetic factors may be of prime importance in determining the response to agents that induce production of fetal hemoglobin.

Adult↗
PubMed1998

Long-term trials of deferiprone in Cooley's anemia.

Deferoxamine is the currently available agent for the iron-chelation therapy required by Cooley's anemia patients. The difficulties associated with parenteral administration have mandated a search for alternative therapies, especially orally active iron chelators, to remove excess iron that results in damage to the liver, endocrine organs, and heart. Four orally active agents have reached clinical trials in the last decade. The agent under consideration in this paper, deferiprone (1,2-dimethyl-3-hydroxypyridin-4-one), has shown some promise, but, according to the studies discussed here, may not provide adequate sustained control of body iron in a substantial proportion of Cooley's anemia patients.

Clinical Trials as Topic↗
PubMed1998

Trying to improve compliance with prophylactic penicillin therapy in children with sickle cell disease.

AIMS: To evaluate compliance with prophylactic penicillin therapy in sickle cell disease (SCD) in children. METHODS: Forty-five children aged 37 +/- 19 (9-84) months [mean +/- s.d; range] with homozygous SCD were recruited. After a baseline period of 2 months the patients were randomized to either the intervention or non-intervention group. The intervention consisted of a slide show explaining the pathogenesis of sickle cell disease and its complications; weekly phone calls by the clinic social worker; and a calendar. Compliance was again evaluated after the 2 month intervention period and after a further 2 month monitoring period without intervention. Compliance was monitored using the Medication Event Monitoring System. At the end of the 6 months, parents in both groups completed a questionnaire the aims of which were to determine knowledge and understanding of sickle cell disease and previous experience with infection. Patient admissions to the hospital during the study were recorded. RESULTS: Compliance during the 2 month baseline assessment was 66.0 +/- 32.5 (1.3-98.2)% and 69.3+25.4 (19.8-96.5)% in the intervention (n = 13) and non-intervention (n = 10) groups respectively (P = 0.79). During the next 2 months, compliance in the intervention group (n = 11) was 79.0 +/- 31.4 (11.0-100.0)% and in the non-intervention group (n = 9) was 66.0 +/- 20.2 (42.2-96.8)% (P = 0.297). In the final 2 month monitoring period compliance was 82.0 +/- 34.7 (3.8-100.0)% and 65.8 +/- 25.3 (25.0-98.2)% in the intervention (n = 7) and the non-intervention (n = 6) groups respectively (P = 0.366). No statistically significant differences were found when comparing compliance between the groups. CONCLUSIONS: Compliance with prophylactic antibiotic therapy in children with sickle cell disease is highly variable and its evaluation is problematic.

Administration, Oral↗