PubMed Health⌕ Search

Biomedical subjects

P Pootrakul

Publications and source records attributed to P Pootrakul.

At least 19 recordsLinked to original sources
PubMed2001

Desferrioxamine-chelatable iron, a component of serum non-transferrin-bound iron, used for assessing chelation therapy.

This study introduces a method for monitoring a component of serum non-transferrin-bound iron (NTBI), termed "desferrioxamine-chelatable iron" (DCI). It is measured with the probe fluorescein-desferrioxamine (Fl-DFO), whose fluorescence is stoichiometrically quenched by iron. DCI was found in the serum of most patients with thalassemia major (21 of 27 tested, range 1.5-8.6 microM), but only in a minority of patients with hereditary hemochromatosis (8 of 95 samples from 39 patients, range 0.4-1.1 microM) and in none of 48 controls. The method was applied to monitoring the appearance of iron in the serum of patients under chelation therapy. Short-term (2 hours) follow-up of patients immediately after oral administration of deferriprone (L1) showed substantial mobilization of DCI into the serum (up to 10 microM within 30-60 minutes). The transfer of DCI from L1 to Fl-DFO was observed in vitro with preformed L1-iron complexes, and occurred even at L1/iron ratios exceeding 3:1. Simultaneous administration of oral L1 and intravenous DFO to patients abrogated the L1-mediated rise in DCI, consistent with the shuttling of iron from L1 to DFO in vivo. A similar iron transfer from L1 to apo-transferrin was observed in vitro, lending experimental support to the notion that L1 can shuttle iron in vivo to other high-affinity ligands. These results provide a rationale for using chelator combinations, with the highly permeant L1 acting as an intracellular chelator-shuttle and the less permeant DFO serving as an extracellular iron sink. Potential applications of the DCI assay may be for studying chelator action and as an index of patient chelation status.

Adolescent↗
PubMed2000

A correlation of erythrokinetics, ineffective erythropoiesis, and erythroid precursor apoptosis in thai patients with thalassemia.

The variety of patients with thalassemia in Thailand offers an opportunity to fully characterize the kinetic causes of the anemia and to study apoptosis of marrow erythroid precursors as a possible factor contributing to its severity. Kinetic studies showed that in hemoglobin H (HbH) disease, the extent of hemolysis, as well as the minimally ineffective erythropoiesis, usually falls within the compensatory capacity of normal erythropoiesis; therefore, anemia in patients with HbH partly represents a failure to expand erythropoiesis adequately. Hemoglobin Constant Spring (HbCS), a common variant of alpha thalassemia in Bangkok, causes more severe hemolysis and a distinct increase in ineffective erythropoiesis. Ineffective erythropoiesis plays a much more prominent role in beta thalassemia/hemoglobin E (beta-thal/HbE) disease, in which the variability of the anemia is puzzling. We compared mild and severe cases and found that patients with severe disease had a maximal marrow erythropoietic response that failed to compensate for very short survival of red blood cells and a marked quantitative increase in ineffective erythropoiesis. Analysis of apoptosis of marrow erythroid precursors done both on shipped samples and in Bangkok showed a moderate increase in HbH disease, consistent with the small increase in ineffective erythropoiesis. In patients with homozygous HbCS, there was a further increase in apoptosis, consistent with the additional increase in ineffective erythropoiesis. Patients with beta-thal/HbE disease had the most ineffective erythropoiesis and the most erythroid apoptosis. Thus, it appears that alpha-chain deposition in erythroid precursors, either alpha(A) or alpha(cs), leads to accelerated apoptosis and ineffective erythropoiesis.

Adolescent↗
PubMed1999

Serum levels of tumor necrosis factor-alpha, interleukin-1, and interferon-gamma in beta(o)-thalassemia/HbE and their clinical significance.

Serum levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-1alpha (IL-1alpha), and interferon-gamma (IFN-gamma) were estimated by conventional ELISA kits in 60, 42, and 58 Thai patients, respectively, with beta(o)-thalassemia HbE and found to be above the normal range in 13%, 21%, and 33% of the patients, respectively. Using high-sensitivity ELISA systems, an additional 10 beta(o)-thal/HbE patients were compared with 9 controls for concentrations of circulating TNF-alpha and IL-1beta, and 9 and 5 patients, respectively, but only 1 and none of the controls, respectively, showed values above the normal ranges. In patients with abnormally high IFN-gamma levels, basal hemoglobin values were significantly lower than in those with normal levels of the cytokine (mean +/- SEM: 6.03+/-0.24 vs. 7.08+/-0.18, p < 0.05), although circulating concentrations of soluble transferrin receptors (sTrF) and absolute reticulocyte counts were similar in the two groups. Patients with raised or normal levels of TNF-alpha, IL-1alpha, or IL-1beta had similar basal hemoglobin values. In a phagocytosis assay, monocytes of patients with raised serum levels of IFN-gamma showed significantly more attached or ingested IgG-coated red cells than those of patients with normal concentrations of the cytokine (mean +/- SEM: 192+/-22 vs. 140+/-14 per 100 monocytes, p < 0.05). Moreover, in 3 of 4 of the former patients, the number of attached or ingested IgG-coated red cells per 100 monocytes was above the 95% reference limit for the latter patients. The results suggest that IFN-gamma aggravates the anemia of beta(o)-thal/HbE by activating mononuclear phagocytes for destruction of red cells but not by inhibiting erythropoiesis. The elevated serum levels of TNF-alpha and IL-1 could contribute to complications of the disease, such as cachexia and thromboembolic phenomena.

Adolescent↗
PubMed1998

The form of iron oxide deposits in thalassemic tissues varies between different groups of patients: a comparison between Thai beta-thalassemia/hemoglobin E patients and Australian beta-thalassemia patients.

Mössbauer spectra of 12 beta-thalassemia/hemoglobin E spleen samples from Thai patients who had not received multiple blood transfusions and chelation therapy and seven beta-thalassemia spleen samples from Australian patients who had received multiple blood transfusions and chelation therapy were recorded with sample temperatures of 78 K. Each spectrum was found to consist of a superposition of a relatively intense central doublet characteristic of high-spin Fe(III), a low intensity sextet of peaks due to magnetic hyperfine-field splitting, and occasionally a doublet that could be attributed to heme iron. A significant (P=0.01) difference (Kolmogorov-Smirnov statistic of 0.71) between the distributions of sextet signal intensity as a fraction (Fs) of the total non-heme iron Mössbauer spectral signal for the two groups of patients was detected. The distribution of Fs for the Thai beta-thalassemia/hemoglobin E spleens had a mean value of 0.128 (S.D. 0.035) while that for the Australian beta-thalassemia spleens had a mean of 0.27 (S.D. 0.12). No significant difference between the distributions of non-heme iron concentrations in the tissues for the two groups of patients was detected by atomic absorption spectrometry. This study shows that the Australian beta-thalassemia patients had a higher fraction of their non-heme spleen iron in a goethite-like form than the Thai beta-thalassemia/Hb E patients.

Chelation Therapy↗
PubMed1998

The course of anaemia after the treatment of acute, falciparum malaria.

To determine the course of anaemia following treatment for acute falciparum malaria, 72 adult Thai patients were followed for 4 weeks after starting effective therapy. Using the criteria of haemoglobin concentrations of < 13 g/dl in males and < 12 g/dl in females to define anaemia, all but two (97%) of the patients were anaemic at some point during the study period. At weekly observations, the erythropoietic response of each patient with anaemia was categorized clinically, on the basis of absolute reticulocyte counts (ARC) and indirect bilirubin concentrations (IBC). At 4 weeks, 40 (56%) of the patients were still anaemic. The results of tests on samples of peripheral blood from these 40 patients were consistent with hypoproliferative erythropoiesis (low-normal ARC and IBC; 33 patients), ineffective erythropoiesis (low-normal ARC but elevated IBC; five patients) or an appropriate response (elevated ARC and normal IBC; two patients). Of the variables measured at the time of enrolment into the study, only low serum albumin (P = 0.002) and elevated direct bilirubin (P = 0.009) were independently associated with persisting anaemia at 4 weeks. Anaemia may therefore persist in about one in every two Thai patients for up to 28 days after beginning effective treatment for acute Plasmodium falciparum malaria, hypoproliferative erythropoiesis appearing to be the most common mechanism of this anaemia. While it is likely that the malarial episode itself is somehow responsible for these persistent haematological changes, other, underlying, chronic processes might have a contributory role. Whatever the cause, the continuing anaemia appears to be related to the degree of hepatic dysfunction on admission.

Adult↗
PubMed1998

Effects of alpha-thalassemia on pharmacokinetics of the antimalarial agent artesunate.

Thalassemia is common in Southeast Asia, where artemisinin derivatives are frequently used in the treatment of malaria. It has been previously reported that artemisinin derivatives can be concentrated by uninfected thalassemic erythrocytes in vitro but not by normal erythrocytes. As a follow-up to this report, we studied the antimalarial kinetics of intravascular artesunate (2.4 mg/kg of body weight) in 10 persons with normal hemoglobins and in 10 patients with thalassemia (2 with alpha-thalassemia type 1-hemoglobin Constant Spring and 8 with alpha-thalassemia type 1-alpha-thalassemia type 2). Concentrations of artesunate and its active metabolites in plasma were measured by bioassay and expressed relative to those of dihydroartemisinin, the major biologically active metabolite. Concentrations of intravascular artesunate in plasma peaked in both the normal individuals and the thalassemic individuals 15 min after injection (the first time point). Plasma drug concentrations at all time intervals, except that at 1 h, were significantly higher in thalassemic subjects than in normal subjects (P < 0.05). The area under the concentration-time curve was 9-fold higher (P < 0.001) and the volume of distribution at steady state was 15-fold lower (P < 0.001) in thalassemic than in normal subjects. In light of the potential neurotoxicity of artemisinin derivatives, these results suggest that thalassemic subjects may need a drug administration regimen different from that of normal patients.

Adolescent↗
PubMed1998

Renal function in adult beta-thalassemia/Hb E disease.

Beta-Thalassemia hemoglobin E (beta-thal/Hb E) is the commonest form of hemoglobinopathy in Thailand. Shortened red cell life span, rapid iron turnover and tissue deposition of excess iron are major factors responsible for functional and physiological abnormalities found in various forms of thalassemia. Increased deposition of iron had been found in renal parenchyma of thalassemic patients, but no systematic study of the effect of the deposits on renal functions has been available. The purpose of this study is to describe the functional abnormalities of the kidney in patients with beta-thal/Hb E and provide evidence that increased oxidative stress might be one of the factors responsible for the damage. Urine and serum samples from 95 patients with beta-thal/Hb E were studied comparing with 27 age-matched healthy controls. No difference in the creatinine clearance was observed. beta-thal/Hb E patients excreted significantly more urinary protein (0.8+/-0.5 vs. 0.3+/-0.1 g/day, p < 0.001). Aminoaciduria was found in 16 % of the patients. Analysis of urinary protein by SDS-PAGE electrophoresis and silver staining revealed abnormal pattern of protein with increased small molecular weight (<45 kD) bands. Morning urine analysis showed significant lower urine osmolality (578.3+/-164.6 vs. 762.4+/-169.9 mosm/kg, p < 0.001) in patients. Patients excreted more NAG (N-acetyl beta-D-glucosaminidase, 26.3+/-41.3 vs. 8.4+/-3.9 U/g Cr, p < 0.0001) and beta2-microglobulin, 124.3+/-167 vs. 71+/-65.5 microg/g Cr, p = 0.001. Plasma and urine MDA (malonyldialdehyde) levels were both raised (p < 0.0001). Nine patients were selected for renal acidification study. All were found to be normal, but showed poor response to DDAVP challenge (urine osmolality 533+/-71). This is the first report of renal tubular defects found associated with beta-thal/Hb E disease. The mechanism leading to the damage is not known but it might be related to increased oxidative stress secondary to tissue deposition of iron, as indicated by the raised levels of serum and urine MDA. It is not known whether these functional defects would have any long-term effects on the patients. Further studies are warranted and means of prevention of these defects should urgently be sought.

Acetylglucosaminidase↗
PubMed1997

The effect of histological processing on the form of iron in iron-loaded human tissues.

Iron-loaded human spleen tissue was immersed in neutral buffered formalin over a period of 200 days. Over the first 60 days, iron leached steadily from the tissue until 3% had been lost. Thereafter, no further iron leaching was detected. Comparisons of Mossbauer spectra of freeze-dried tissue and tissue freeze-dried after immersion in formalin for 200 days showed no evidence of chemical transformation of the iron remaining in the tissue. The spectra indicated a difference in the heme-iron to non-heme iron ratio between the two samples probably reflecting inhomogeneity of the ratio throughout the spleen as measured on the centimetre scale. Mossbauer spectra of freeze-dried samples of iron-loaded human liver and pancreas tissue were compared with those for samples from the same patient that had been processed by routine hospital procedures for histology and archival. These spectra showed no evidence for chemical transformation of the iron present in the tissues. These results demonstrate that it is feasible to use archived fixed and embedded human tissue samples for studies aimed at gauging the relative fraction of goethite-like hemosiderin present in the tissue.

Formaldehyde↗
PubMed1996

Hydroxyurea increases hemoglobin F levels and improves the effectiveness of erythropoiesis in beta-thalassemia/hemoglobin E disease.

Hydroxyurea (HU) is one of several agents that have been shown to enhance hemoglobin (Hb) F levels in patients with sickle cell disease and may be useful as a therapy for beta-globinopathies. However, limited information exists on the effects of HU in patients with thalassemia. Accordingly, we examined the hematologic effects of orally administered HU in 13 patients with beta-thalassemia/Hb E, including four patients who had been splenectomized. These patients were treated with escalating doses (final range, 10 to 20 mg/kg/d) for 5 months and were observed in the outpatient hematology clinic every 2 to 4 weeks. Complete blood counts including reticulocyte counts, amounts of Hb E and Hb F, G gamma:A gamma and alpha:non-alpha globin biosynthetic ratios were evaluated before and during treatment. Almost all patients responded with an average increase of 33% in Hb F levels, from a mean (+/- SD) of 42% +/- 11% to 56% +/- 8% (P < .0001), and a reciprocal decline in the percentage of Hb E from 59% +/- 9% to 49% +/- 8% (P < .001). Reticulocytosis was decreased from a mean (+/- SD) of 18.0% +/- 15.6% to 11.7% +/- 9.1% (P < .05); there was also a slight (10%) but statistically significant increase in hemoglobin levels and an improved balance in alpha:non-alpha globin chains ratios. The side effects were minimal in most patients, although these patients tended to tolerate a lower dose of HU before significant myelosuppression than has been our previous experience in sickle cell disease. One splenectomized patient died of sepsis during the trial. We conclude that increased Hb F production in beta-thalassemia/Hb E patients, with an improvement in the alpha:non-alpha globin ratios and, probably, the effectiveness of erythropoiesis, can be achieved using HU. Longer trials of HU in this population, including at other doses and in combination with other agents, appear warranted.

Adolescent↗
PubMed1995

Glomerulonephritis in beta-thalassemia Hb-E disease: clinical manifestations, histopathologic studies and outcome.

We presented 8 patients with beta-thal/Hb E with glomerular diseases. Diverse glomerular lesions were seen, but diffuse endocapillary glomerulonephritis was the most common. The clinical manifestations of acute glomerulonephritis in beta-thal/Hb E differed from typical cases in the older age group, female preponderance, longer duration of edema, less hypertension, marked proteinuria, hypoalbuminemia and hypertriglyceridemia and also a longer period of recovery but their outcome was still favorable despite many risk factors of renal injury. Renal biopsy was necessary in doubtful cases to detect the correct diagnosis and give proper management. The association and mechanism of glomerulonephritis in these patients require further prospective study.

Adolescent↗
PubMed1993

Quantitative assessment of erythropoiesis and functional classification of anemia based on measurements of serum transferrin receptor and erythropoietin.

We evaluated the quantitative value of a simple model of erythropoiesis, based on the basic assumptions that the red blood cell (RBC) mass determines erythropoietin (Epo) production, which in turn stimulates erythropoietic activity. The RBC mass was quantitated by direct isotopic measurement (RCM), Epo production by serum Epo levels, and erythropoiesis by the ferrokinetic measurement of the erythron transferrin uptake (ETU), the serum transferrin receptor (TfR) level, and the reticulocyte (retic) index, and was completed by an evaluation of overall marrow erythron cellularity. We studied a total of 195 subjects, including 31 normal individuals, 38 patients with polycythemia, and 126 patients with various forms of anemia. Instead of only quantitating Epo and erythropoiesis in absolute terms, we also evaluated them in relation to the degree of anemia or polycythemia, and expressed the results as a ratio of observed values to values predicted from the regression equations between hematocrit (Hct) on the one hand, and Epo, TfR, and ETU on the other, obtained in a carefully selected subpopulation. The slope of the regression of TfR (as well as ETU) versus Hct was very similar to the slope of the regression of Epo versus Hct. Average EPO and TfR (as well as ETU) values predicted from the regression equations were quite comparable to observed values in most groups of subjects, with exceptions predictable from knowledge of the pathophysiology of these hematologic disorders. We identified four major patterns of erythropoiesis, ie, normal, hyperdestruction (with variants of hemolysis or ineffective erythropoiesis), intrinsic marrow hypoproliferation, and defective Epo production. Dissecting out groups of patients showed much greater heterogeneity than when patients were analyzed by group. This was particularly true in the case of a hypoproliferative component being combined with hyperdestruction, giving what we called a "mixed disorder of erythropoiesis." We conclude that the pathophysiology of anemia can be assessed by a simple measurement of Hct, retic index, Epo, and TfR levels, with Epo and TfR being more informative when expressed in relation to the degree of anemia. The model is particularly useful for detecting the presence of multiple mechanisms of anemia in the same patient. However, it has limitations inherent to the relative invalidity of TfR in iron deficiency, the imprecision of a retic count, and the difficulty in distinguishing hemolysis from ineffective erythropoiesis in some patients and in recognizing a component of hyperdestruction in hypoproliferative anemia.

Adolescent↗
PubMed1991

Organ-specific crystalline structures of ferritin cores in beta-thalassemia/hemoglobin E.

The cores of ferritins isolated from different organs of human subjects with beta-thalassemia/hemoglobin E (beta-thal/HbE) disease have different size distributions and crystallinities depending on the source organ. These patients have not been treated by hypertransfusion regimen or iron chelation therapy. beta-Thal/HbE spleens and livers yield ferritin cores which are less crystalline than those isolated from normal spleens and livers, reflecting the more rapid deposition of iron in the diseased state. Ferritins isolated from the hearts and pancreases of beta-thal/HbE subjects were found to have larger, more crystalline cores than those from the beta-thal/HbE livers and spleens, possibly as a consequence of the role of the heart and pancreas as long-term iron deposition sites in this iron overload pathology.

Ferritins↗
PubMed1991

Pituitary function in thalassemic patients and the effect of chelation therapy.

This study examined anterior pituitary function and the effect of chelation therapy in 31 patients with beta-thalassemia/HbE disease. Patients were divided into those receiving chelation therapy by deferoxamine and those receiving no such therapy (control group). Pituitary function studies were repeated in both groups 18 months later. The results showed decreased pituitary responses following stimulation in 22 patients. Among these, gonadotropin and PRL responses were most affected. After 18 months, serum ferritin levels had significantly decreased in the deferoxamine group. PRL and GH responses were improved in 3 patients receiving chelation therapy without changes in other hormone responses. In contrast, no changes in pituitary responses were shown in the control group at the end of follow-up. There were 6 drop-outs (4 in the control and 2 in the deferoxamine group) and 3 deaths (2 in the control and 1 in the deferoxamine group) during 18 months. In conclusion, gonadotropin and PRL deficiencies occur most frequently in thalassemic patients. Chelation therapy for 18 months markedly reduced serum ferritin level and might preserve or improve PRL and GH secretions, but seems to have no beneficial effects on other pituitary hormone reserves.

Adult↗
PubMed1991

High-dose intravenous immunoglobulin in the management of immune hemolysis in patients with thalassemic disease: factors which determine refractoriness.

We report our experience with high dose intravenous immunoglobulin (IVIg) in 3 thalassemic patients who had evidence of possible immune hemolysis. In 2 patients who had serious sepsis, their responses to IVIg were only partial and transient. The other patient who had marked splenomegaly had no evidence of response to IVIg. Both serious infections and large spleen may hamper the effect of IVIg and should be considered before IVIg is to be used in thalassemia.

Adult↗
PubMed1991

Red cell and plasma calcium, copper and zinc in beta-thalassemia/hemoglobin E.

Beta-thalassemia/Hb E is a genetic disease prevalent in Thailand. This study has used atomic absorption spectroscopy to evaluate red cell and plasma calcium, copper and zinc in patients with beta-thalassemia/Hb E, both splenectomized and non-splenectomized. The levels of these trace elements in both red cells and plasma were different between the non-thalassemic controls and the disease patients. The most prominent result was that calcium concentration in red cells increased significantly in thalassemia subjects, particularly in splenectomized cases. These results might reflect the abnormal trace element metabolism and defects in the calcium transport system of the red cell membrane in thalassemia.

Adult↗
PubMed1990

Intact transferrin receptors in human plasma and their relation to erythropoiesis.

Intact transferrin receptor molecules complexed with transferrin were found in human plasma. The concentration of receptors was determined by an enzyme-linked immunosorbent assay that uses polyclonal antibodies. The mean concentration of 8,279 micrograms/L in 56 normal adults appears to be unrelated to age or sex. Additional receptor measurements were performed on plasmas from 260 subjects with erythropoietic disorders. Decreased concentration of plasma receptors was found in patients with erythroid hypoplasia and increased numbers in those with erythroid hyperplasia. Ferrokinetic measurements of erythropoiesis were compared with numbers of receptors in 148 subjects, and a close correlation was found (r = .86). Both sets of values, measured in different conditions and expressed in relation to normal, were consistent with expected values. Receptor values were unproportionally increased only in conditions of iron deficiency. It is concluded that plasma receptors have a constant relationship to tissue receptors, and their number in most instances reflects the rate of erythropoiesis.

Erythropoiesis↗