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Biomedical subjects

S Fucharoen

Publications and source records attributed to S Fucharoen.

At least 163 records · Page 9Linked to original sources
PubMed1989

Heterogeneity of the gamma-globin gene sequences in Japanese individuals: implication of gene conversion in generation of polymorphisms.

The linked fetal globin genes (the G gamma- and A gamma-globin genes) were cloned from Japanese individuals with three different haplotypes of the HindIII polymorphisms within the gamma-globin genes. Determination of nucleotide sequences of the segment spanning from IVS2 to the 3' flanking region of each gamma-globin gene revealed that nucleotide differences are located at 43 positions and a stretch of simple GT or GC sequences. Almost half of the nucleotide changes could be accounted for by gene conversion between the G gamma- and A gamma-globin genes. We found that gene conversion had created the SacI polymorphic site just downstream of the A gamma-globin coding region. Association of the SacI polymorphic site with the HindIII polymorphic site suggests that the region containing these two sites was derived from that of the linked G gamma-globin gene through a gene conversion event. The nucleotide sequences obtained here are identical to those of the Caucasoid fetal globin genes of the same haplotypes, with the exception of some sequence changes in the hot spots of mutations. These results indicate that the sequence heterogeneity of the gamma-globin genes can be classified into three major categories according to HindIII haplotypes. The possible mechanisms of generation of the heterogeneity of the gamma-globin gene sequences are discussed.

Base Sequence↗
PubMed1989

Decreased sensitivity of artesunate and chloroquine of Plasmodium falciparum infecting hemoglobin H and/or hemoglobin constant spring erythrocytes.

Plasmodium falciparum infecting hemoglobin (Hb) H and/or Hb Constant Spring erythrocytes in vitro was relatively more resistant than that infecting normal erythrocytes to artesunate and chloroquine, while the sensitivity to pyrimethamine was unchanged. The 50% inhibitory concentrations (IC50) for artesunate in HbH (alpha-thal 1/alpha-thal 2), HbH (alpha-thal 1/Hb Constant Spring), and homozygous Hb Constant Spring erythrocytes were 4.5 +/- 2.8, 8.5 +/- 3.2, and 2.6 +/- 1.6 nM compared with 0.82 +/- 0.35 nM in normal erythrocytes (P less than 0.002 for all three cases). The IC50 for chloroquine were 97 +/- 46, 162 +/- 67, and 93 +/- 36 nM, respectively, in the variant erythrocytes, compared with 48 +/- 13 nM in normal erythrocytes (P less than 0.002, 0.002, and 0.02, respectively). The differences in sensitivity to artesunate and chloroquine of the parasite infecting HbH erythrocytes are probably related to their oxidative mode of action and relatively high amounts of antioxidant enzymes in the host erythrocytes. This novel example of dependence on the host of the malarial parasite drug sensitivity may have implications for chemotherapy of malaria in patients with genetically variant erythrocytes.

Animals↗
PubMed1989

The molecular basis of AE-Bart's disease.

AE-Bart's disease is a thalassemia intermedia resulting from the interaction between alpha-thalassemia and heterozygous Hb E. In this study we analyzed the alpha-globin genes of 25 patients designated as AE-Bart's disease by starch gel electrophoresis. Twenty-one cases had Hb Constant Spring in addition to Hbs E + A + Bart's, and the remaining four cases had only Hbs E + A + Bart's. DNA mapping revealed the alpha-globin genotype of alpha-thalassemia-1/alpha-thalassemia-2 in four patients who had Hbs E + A + Bart's, whereas the alpha genotype of the remainder is alpha-thalassemia-1/nondeletion alpha-thalassemia. The nondeletion alpha-thalassemia is Hb Constant Spring as indicated by starch gel electrophoresis. Hematologic data and hemoglobin analysis showed that Constant Spring-AE-Bart's disease is a more severe clinical syndrome than AE-Bart's disease.

Adolescent↗
PubMed1989

Analysis of hematological data of thalassemia cases in Thailand.

We analyzed the complete blood count (CBC) obtained from patients with various types of thalassemia in Thailand. As a control, samples from healthy donors and patients with iron deficiency anemia were also collected. Most cases of thalassemia could be differentiated from iron deficiency anemia by using a discrimination function equation. This screening method is applicable for mass-screening of patients with latent thalassemia in Thailand.

Erythrocyte Count↗
PubMed1989

Laboratory diagnosis for thalassemia.

Thalassemia is one of the common genetic disorders worldwide. alpha-thalassemia, beta-thalassemia, Hb E and Hb Constant Spring are common mutations found in S E Asia. The diagnoses of thalassemia and some abnormal hemoglobin carriers are very crucial for the identification of a high risk couple who will need further investigation of prenatal diagnosis. Determination of any thalassemic disease such as Hb H disease, homozygous beta-thalassemia, beta-thalassemia/Hb E can be carried out easily from the clinical findings, changes in hematologic data and hemoglobin electrophoresis. But the diagnoses of thalassemia carriers are cumbersome and sometimes need very sophisticated techniques of in vitro protein synthesis and DNA analysis. In this paper we review the laboratory methods and strategies for the diagnosis of thalassemia and abnormal hemoglobin commonly found in S E Asia.

Clinical Laboratory Techniques↗
PubMed1989

Study of mechanisms of post-transfusion hypertension in thalassaemic patients.

Post-transfusion hypertension, convulsion and cerebral haemorrhage is a serious complication that may occur in the thalassaemias. In this study we evaluated the effect of blood transfusion on blood pressure, plasma renin activity (PRA), blood viscosity, and urinary vanillylmandelic acid (VMA) and catecholamines in 11 beta-thalassaemia/haemoglobin E patients. The results showed that after each unit of blood transfusion the blood viscosity was increased and correlated with the increased in haematocrit level. At the same time the PRA level was significantly decreased and tended to return to the normal level in a few days after the transfusion. There was no alteration in the urinary VMA and catecholamine levels. During the study two patients developed hypertension and headache. Their PRA were still lower than the pre-transfusion levels and the blood pressure returned to the normal pre-transfusion levels within 30-90 minutes after the intravenous injection of furosemide.

Adolescent↗
PubMed1989

Cytochemical evaluation of neutrophil components in beta thalassemia hemoglobin E.

The mean +/- S.D. of LAP score in neutrophil of the normal control, non splenectomised patients and splenectomised patients were 116 +/- 78, 94 +/- 48 and 37 +/- 23 Kaplow units, respectively. The significant reduction in the leukocyte alkaline phosphatase level (P less than 0.05) was found in beta thalassemia/HbE patients. The degree of reduction was greater in the splenectomised patients (P less than 0.05). The decreased LAP levels in PMN was persistent. This was in contrast to the LAP in PMN of other patients where as LAP returned to normal after splenectomy. The relevance to the increased susceptibility to infection and low LAP in beta thalassemia/HbE should be further investigated.

Alkaline Phosphatase↗
PubMed1988

Cord blood study on beta-thalassemia and hemoglobin E.

We describe hematologic data from 18 newborn infants including follow-up data. Of these, ten were the offspring of patients with beta-thal/Hb E disease and the remainder were infants who were found to have a decrease in red cell osmotic fragility during a random cord blood examination. The results of the cord blood study showed that two infants having normal red cell osmotic fragility with about 2% Hb E + Hb A + Hb F at birth represented Hb E heterozygosity. Eleven babies had slightly decreased red cell osmotic fragility, a mild degree of microcytosis and poikilocytosis, and hemoglobin types of Hb A + Hb F with no elevation of Hb A2 at birth. They subsequently had hematologic findings consistent with the beta-thal heterozygosity. The means of hematological values of cord blood in the beta-thal trait infants appeared to be statistically different from those in the normal infants only with respect to increased red cell count and reduced MCH. One infant was thought to have the beta-thal trait but had a greater degree of thalassemic changes in red cells; subsequently he turned out to have homozygous beta-thalassemia. Four newborn infants with hypochromia and numerous target cells had 4-7% Hb E + Hb F without Hb A. Follow-up examination showed two cases of Hb E homozygosity; however, the others, who had obvious microcytosis and poikilocytosis in cord blood, finally developed beta-thal/Hb E disease. Thus, a careful study on red cell osmotic fragility, morphology and starch gel electrophoresis at birth allows detection and diagnosis of beta-thal heterozygosity, beta-thal homozygosity, Hb E heterozygosity, Hb E homozygosity and double heterozygosity for beta-thal and Hb E.

Fetal Blood↗
PubMed1988

Differentiation of Plasmodium falciparum clones by means of a repetitive DNA probe.

A recombinant DNA probe, pBRK1-14, was constructed by inserting a repetitive DNA fragment of 753 base pairs obtained from Plasmodium falciparum, isolate K1, into the EcoRI/PstI cloning sites of pBR322. This probe could discriminate between different parasite clones derived from a single isolate by hybridization with Southern genomic blots.

Animals↗
PubMed1988

Impaired parasite growth and increased susceptibility to phagocytosis of Plasmodium falciparum infected alpha-thalassemia or hemoglobin Constant Spring red blood cells.

In vitro multiplication of Plasmodium falciparum in hemoglobin H or hemoglobin Constant Spring red blood cells (from homozygotes or double heterozygotes) was significantly reduced as compared with that in normal erythrocytes. The parasitized genetically abnormal red blood cells showed furthermore a high propensity for being phagocytosed by peripheral blood monocytes. Both impaired parasite growth and increased susceptibility to phagocytosis may be related to mechanisms for protection of the variants from P. falciparum infection.

Animals↗
PubMed1988

Hematologic changes in alpha-thalassemia.

Alpha-thalassemia is very common in Thailand. Interaction of the different types of alpha-thalassemia can lead to many alpha-thalassemia syndromes. In this study the authors compare the hematologic data of subjects with various alpha-thalassemia phenotypes. Designation of the genotypes was based on family study and DNA mapping. The results show that there are equivocal hematologic findings among those who have similar molecular defects, i.e., alpha-thalassemia-2 and hemoglobin (Hb) Constant Spring heterozygotes: alpha-thalassemia 1, homozygous alpha-thalassemia 2, and alpha-thalassemia 2/Hb Constant Spring. The severity of these alpha-thalassemia syndromes correlates with the alpha-globin gene expression calculated from the finding of Liebhaber (Liebhaber SA, et al. J Biol Chem 1986; 261:15327-15333).

DNA↗
PubMed1988

EF Bart's disease: interaction of the abnormal alpha- and beta-globin genes.

EF Bart's disease is an uncommon form of thalassaemia intermedia resulting from the co-inheritance of alpha-thalassaemia and haemoglobin E in the same subject. Starch-gel electrophoresis revealed two phenotypes in 19 patients with EF Bart's. 16 patients had Hbs CS + E + F + Bart's and the remainder had Hbs E + F + Bart's. DNA mapping and haemoglobin electrophoresis indicated that there are four genotypes, involving 5 abnormal globin genes, responsible for this thalassaemia syndrome.

Adolescent↗
PubMed1988

Alpha-thalassemia in Thailand.

The alpha-thalassemia syndromes are remarkable both for their phenotypic diversity and for their different clinical severity. They are associated with variable degrees of alpha-chain deficits; the clinical manifestations range from asymptomatic cases with normal hematologic findings to the totally lethal Hb Bart's hydrops fetalis syndrome. Recent molecular biology studies have clarified the defects in these alpha-thalassemia syndromes around the world. This paper describes the alpha-thalassemias in Thailand, and covers the types, molecular defects, incidence of each genotype, and their phenotypic expression.

Fetal Blood↗
PubMed1988

Beta-thalassemia associated with alpha-thalassemia in Thailand.

In Thailand alpha-thalassemia (thal), beta-thal, hemoglobin (Hb) E and Hb Constant Spring (Hb CS) are prevalent. The incidences are 20-30% for alpha-thal (3.5% for alpha-thal-1 and 16% for alpha-thal-2), 3-9% for beta-thal, up to 54% for Hb E and nearly 8% for Hb CS. Different combinations of these genes result in a spectrum of thalassemia syndromes ranging in severity from asymptomatic to intrauterine death. From the known gene frequencies the numbers of thalassemic patients per generation (total population of 50 million) are as follows: Hb Bart's hydrops fetalis 20,000; homozygous beta-thal 31,250; beta-thal/Hb E disease 162,500; Hb H disease (two genotypes) 200,000, making a total of 413,750. In addition, individuals may carry more than two of the abnormal genes leading to complex thalassemia syndromes such as alpha beta-thal, AE-Bart's and EF-Bart's diseases.

Gene Frequency↗
PubMed1988

The effect of erythroid hyperplasia on iron balance.

Measurements of erythropoiesis and iron balance were made in eight normal and 32 anemic subjects. The latter consisted of 12 individuals with ineffective erythropoiesis (beta-thalassemia/hemoglobin E), 13 subjects with ineffective erythropoiesis and hemolytic anemia (hemoglobin H), and seven subjects with hemolytic anemia (hereditary spherocytosis). A consistent relationship within each group existed between the degree of erythropoiesis and radioiron absorption. Although the effect of erythropoiesis on iron absorption was of similar magnitude in the two thalassemia groups, the effect in hereditary spherocytosis was much less. There was agreement between absorption and ferritin or magnetic susceptibility (SQUID) measurements of iron stores in thalassemia, but in hereditary spherocytosis a discrepancy existed between absorption and ferritin. It is concluded that, although increased erythropoiesis is associated with increased iron absorption, some additional factor associated with red cell breakdown is more directly responsible for the positive iron balance in thalassemia.

Adolescent↗
PubMed1988

Histochemical study of liver tissue from thalassemic patients.

The livers of 30 cases of advanced thalassemia were studied pathologically. Severe degrees of hemosiderosis and fibrosis were found in liver cells and Kupffer cells in most cases. Various histochemical stains have been used to determine the characteristics of FAB and to grade degrees of iron deposit and fibrosis. The correlation between hemosiderosis and fibrosis as well as the presence of FAB are described.

Adult↗