This is an exploratory study of the application of a support tool for the detection of asymptomat... more This is an exploratory study of the application of a support tool for the detection of asymptomatic subjects carrying enteric parasites in two vulnerable populations in Argentina: a shantytown in the city of Buenos Aires and a rural Wichí indigenous community in the province of Chaco. The ethnic and cultural diversity, high illiteracy rate, and language barriers called for the development of an auxiliary resource to explain stool sample collection procedures. In individual interviews with each family, the authors used two instructional guidance leaflets in comic strip format depicting the procedures. They evaluated the acceptance of the graphical communication tool on the basis of the number of retrieved samples. Percentages of respondent families were 72.2% and 66.7%, respectively. Definitive validation of these instruments would allow their use in community studies, community service learning experiences, and research on aboriginal communities that would otherwise be excluded from studies on health status.
In this work we describe a flow cytometry–based method using SYTO16 (a DNA intercalating agent) t... more In this work we describe a flow cytometry–based method using SYTO16 (a DNA intercalating agent) to quantify Anaplasma marginale–infected erythrocytes in blood from bovine animals. The linearity and reproducibility of the results obtained with SYTO16 labeling followed by flow cytometry analysis make it a suitable approach for measurement of parasitemia in A. marginale infections.
Erythropoietin (Epo) promotes the development of erythroid progenitors by triggering intracellula... more Erythropoietin (Epo) promotes the development of erythroid progenitors by triggering intracellular signals through the binding to its specific receptor (EpoR). Previous results related to the action of aluminum (Al) on erythropoiesis let us suggest that the metal affects Epo interaction with its target cells. In order to investigate this effect on cell activation by the Epo–EpoR complex, two human cell lines with different dependence on Epo were subjected to Al exposure. In the Epo-independent K562 cells, Al inhibited Epo antiapoptotic action and triggered a simultaneous decrease in protein and mRNA EpoR levels. On the other hand, proliferation of the strongly Epo-dependent UT-7 cells was enhanced by long-term Al treatment, in agreement with the upregulation of EpoR expression during Epo starvation. Results provide some clues to the way by which Epo supports cell survival and growth, and demonstrate that not all the intracellular factors needed to guarantee the different signaling pathways of Epo-cell activation are available or activated in cells expressing EpoR. This study then suggests that at least one of the mechanisms by which Al interfere with erythropoiesis might involve EpoR modulation.
Biochimica Et Biophysica Acta-molecular Cell Research, Jan 1, 2005
Aluminum (Al) and iron (Fe) share several physicochemical characteristics and they both bind to t... more Aluminum (Al) and iron (Fe) share several physicochemical characteristics and they both bind to transferrin (Tf), entering the cell via Tf receptors (TfR). Previously, we found similar values of affinity constant for the binding of TfR to Tf carrying either Al or Fe. The competitive interaction between both metals prevented normal Fe incorporation into K562 cells and triggered the upregulation of Fe transport. In the present work we demonstrated that Al modified Fe uptake without affecting the expression of Tf receptors. Both TfR and TfR2 mRNA levels, evaluated by RT-PCR, and TfR antigenic sites, analyzed by flow cytometry, were found unchanged after Al exposure. In turn, Al did induce upregulation of non-Tf bound Fe (NTBI) uptake. This modulation was not due to intracellular Fe decrease since NTBI transport proved not to be regulated by Fe depletion. Unlike its behavior in the presence of Tf, Al was unable to compete with NTBI uptake, suggesting that both metals do not share the same alternative transport pathway. We propose that Al interference with TfR-mediated Fe incorporation might trigger the upregulation of NTBI uptake, an adaptation aimed at incorporating the essential metal required for cellular metabolism without allowing the simultaneous access of a potentially toxic metal.
There is evidence that anaemia is associated with aluminium (Al). We have already reported on the... more There is evidence that anaemia is associated with aluminium (Al). We have already reported on the sensitivity to Al, showed by erythroid cell populations of animals chronically exposed to the metal. In order to investigate whether Al could also affect human cells, experiments were carried out both on immature and mature human erythroid cells. Erythroid progenitors (CFU-E, colony-forming units-erythroid) concentrated from human peripheral blood were cultured in an Al-rich medium under erythropoietin stimulation and their development analysed. Human peripheral erythrocytes were aged in the presence of Al. Cells were examined using scanning electron microscopy, and membrane proteins analysed by polyacrylamide gel electrophoresis with sodium dodecyl sulphate and immunoblotting. The development of the Al-treated progenitors was 8750/6600–9200 CFU-E/106 cells, a significantly lower median value (P<0.05) than that showed by non-treated cells (12 300/11 200–20 700 CFU-E/106 cells). Erythrocyte morphological changes were induced by Al during the in vitro ageing. The cells lost their typical biconcave shape, turning into acanthocytes and stomatocytes. Simultaneously, an increased membrane protein breakdown compatible with band 3 degradation was detected. Besides, Al was found within the cells and attached to the membrane. The present in vitro results suggest that Al may disturb human erythropoiesis through combined effects on mature erythrocytes and cellular metabolism in late erythroid progenitors.
Aluminium (Al) affects erythropoiesis but the real mechanism of action is still unknown. Transfer... more Aluminium (Al) affects erythropoiesis but the real mechanism of action is still unknown. Transferrin receptors (TfR) in K562 cells are able to bind Tf, when carrying either iron (Fe) or Al, with similar affinity. Then, the aim of this work was to determine whether Al could interfere with the cellular Fe uptake and utilisation. K562 cells were induced to erythroid differentiation by either haemin (H) or sodium butyrate (B) and cultured with and without Al. The effect of Al on cellular Fe uptake, Fe incorporation to haem and cell differentiation was studied. H- and B-stimulated cells grown in the presence of 10 μM Al showed a reduction in the number of haemoglobinised cells (by 18% and 56%, respectively) and high amounts of Al content. Al2Tf inhibited both the 59Fe cellular uptake and its utilisation for haem synthesis. The removal of Al during the 59Fe pulse, after a previous incubation with the metal, allowed the cells to acquire Fe quantities in the normal range or even exceeding the amounts incorporated by the respective control cells. However, the Fe incorporated to haem could not reach control values in B-stimulated cells despite enough Fe acquisition was observed after removing Al. Present results suggest that Al might exert either reversible or irreversible effects on the haemoglobin synthesis depending on cellular conditions.
It has been suggested that aluminium (Al) has a deleterious effect on erythropoiesis. However, th... more It has been suggested that aluminium (Al) has a deleterious effect on erythropoiesis. However, there is still uncertainty as to its action mechanism. The present work was designed to determine how Al could affect the iron (Fe) metabolism in the human erythroleukaemia cell line K562. These cells, that express surface transferrin receptors (TfRs), were induced to erythroid differentiation by either haemin or hydroxyurea in 72 h cultures in media containing apotransferrin (apoTf). In the presence of aluminium citrate, the number of benzidine-positive cells decreased 18% when the cultures were induced by haemin, and 30% when hydroxyurea was the inducer. Cell viability was always unaffected. From competition assays, surface binding of 125I–Tf–Fe2 was found to be inversely related (p<0.05) to Tf–Al2 concentration (from 2.5 to 10 nM). The dissociation constants (Kd) of the binding reaction between TfRs and the ligands Tf–Fe2 and Tf–Al2 were calculated. Kd values of the same order of magnitude demonstrated that TfR has a similar affinity for Tf–Fe2 (Kd=1.75×10−9 M) and Tf–Al2 (Kd=1.37×10−9M). The number of surface TfRs, measured by kinetic 125I–Tf–Fe2 binding assays, was higher in induced cells cultured in the presence of Al. Nevertheless, in spite of the inhibition of cell haemoglobinisation observed, 59Fe incorporation values were not different from those measured in control cultures for 72 h. As a consequence, it can be suggested that cellular Fe utilisation, and not Fe uptake, might be the main metabolic pathway impaired by Al.
Anaemia has been associated with aluminium (Al) accumulation in plasma and/or bone tissue in pati... more Anaemia has been associated with aluminium (Al) accumulation in plasma and/or bone tissue in patients with chronic renal insufficiency. Nevertheless, in previous works, we have found shortened red-cell life span, increased osmotic resistance and inhibition of colony-forming units-erythroid (CFU-E) development in Al-overloaded rats with normal renal function. To elucidate further the action of Al on in vivo erythropoiesis, aluminium citrate was provided to Sprague Dawley rats (n=18) in the drinking water for 8 months. Significant decreases in haematocrit (38.8±4.29 versus 43.1±3.58%, p<0.05) and blood haemoglobin concentration (137±10.1 versus 148±8.5 g/l, p<0.05), reticulocytosis (1.8/1.3–4.2 versus 1.2/0.4–3.7%, p<0.05), and severe inhibition of CFU-E growth (670/120–950 versus 1530/810–2440 CFU-E/2×105 cells, p<0.005) were found. Anysocytosis, poikilocytosis and schistocytosis were detected in peripheral blood stained films. Scanning electron microscopy revealed the presence of erythrocytes with abnormal shape, including crenated and target cells. Aluminium was localised specially inside the schistocytes by EDAX analysis. Decreased haptoglobin concentration (107/83–127 versus 139/89–169 mg/l, p<0.05) supports the assumption of haemolytic nature of the anaemia. Rats were not iron depleted, as plasma iron concentration and total iron binding capacity were found in the range of control values, and sideroblasts and haemosiderin deposits were observed in bone marrow smears. Total 59Fe uptake and 59Fe incorporated to haem by the bone marrow cells were found decreased. In conclusion, the erythropoiesis impairment induced by Al may be a combined effect of direct action on circulating erythrocytes and interference with the cellular iron metabolism in erythroid progenitors.
To determine if there are differences in urinary glycosaminoglycan (GAG) concentrations, 43 stone... more To determine if there are differences in urinary glycosaminoglycan (GAG) concentrations, 43 stone-forming patients and 37 healthy control subjects of both sexes were studied. Urinary concentrations of calcium, magnesium, creatinine, uric acid and GAGs were determined. GAGs were measured by the Di Ferrante precipitation procedure followed by the Bitter and Muir reaction. Urinary GAG concentration and daily output were significantly
… and Alzheimers Disease. Elsevier, Amsterdam, cap, Jan 1, 2001
... Mechanisms Related to Cellular Dysfunction in Alzheimer&amp;amp;#x27;s Disease Alcira Nes... more ... Mechanisms Related to Cellular Dysfunction in Alzheimer&amp;amp;#x27;s Disease Alcira Nesse* and Graciela Garbossa Departamento de Quimica Biologica, Facultad de ... as a contributing factor to aggravate anaemia of end-stage renal disease—was first noticed in the Elliot and McDougall ...
This is an exploratory study of the application of a support tool for the detection of asymptomat... more This is an exploratory study of the application of a support tool for the detection of asymptomatic subjects carrying enteric parasites in two vulnerable populations in Argentina: a shantytown in the city of Buenos Aires and a rural Wichí indigenous community in the province of Chaco. The ethnic and cultural diversity, high illiteracy rate, and language barriers called for the development of an auxiliary resource to explain stool sample collection procedures. In individual interviews with each family, the authors used two instructional guidance leaflets in comic strip format depicting the procedures. They evaluated the acceptance of the graphical communication tool on the basis of the number of retrieved samples. Percentages of respondent families were 72.2% and 66.7%, respectively. Definitive validation of these instruments would allow their use in community studies, community service learning experiences, and research on aboriginal communities that would otherwise be excluded from studies on health status.
In this work we describe a flow cytometry–based method using SYTO16 (a DNA intercalating agent) t... more In this work we describe a flow cytometry–based method using SYTO16 (a DNA intercalating agent) to quantify Anaplasma marginale–infected erythrocytes in blood from bovine animals. The linearity and reproducibility of the results obtained with SYTO16 labeling followed by flow cytometry analysis make it a suitable approach for measurement of parasitemia in A. marginale infections.
Erythropoietin (Epo) promotes the development of erythroid progenitors by triggering intracellula... more Erythropoietin (Epo) promotes the development of erythroid progenitors by triggering intracellular signals through the binding to its specific receptor (EpoR). Previous results related to the action of aluminum (Al) on erythropoiesis let us suggest that the metal affects Epo interaction with its target cells. In order to investigate this effect on cell activation by the Epo–EpoR complex, two human cell lines with different dependence on Epo were subjected to Al exposure. In the Epo-independent K562 cells, Al inhibited Epo antiapoptotic action and triggered a simultaneous decrease in protein and mRNA EpoR levels. On the other hand, proliferation of the strongly Epo-dependent UT-7 cells was enhanced by long-term Al treatment, in agreement with the upregulation of EpoR expression during Epo starvation. Results provide some clues to the way by which Epo supports cell survival and growth, and demonstrate that not all the intracellular factors needed to guarantee the different signaling pathways of Epo-cell activation are available or activated in cells expressing EpoR. This study then suggests that at least one of the mechanisms by which Al interfere with erythropoiesis might involve EpoR modulation.
Biochimica Et Biophysica Acta-molecular Cell Research, Jan 1, 2005
Aluminum (Al) and iron (Fe) share several physicochemical characteristics and they both bind to t... more Aluminum (Al) and iron (Fe) share several physicochemical characteristics and they both bind to transferrin (Tf), entering the cell via Tf receptors (TfR). Previously, we found similar values of affinity constant for the binding of TfR to Tf carrying either Al or Fe. The competitive interaction between both metals prevented normal Fe incorporation into K562 cells and triggered the upregulation of Fe transport. In the present work we demonstrated that Al modified Fe uptake without affecting the expression of Tf receptors. Both TfR and TfR2 mRNA levels, evaluated by RT-PCR, and TfR antigenic sites, analyzed by flow cytometry, were found unchanged after Al exposure. In turn, Al did induce upregulation of non-Tf bound Fe (NTBI) uptake. This modulation was not due to intracellular Fe decrease since NTBI transport proved not to be regulated by Fe depletion. Unlike its behavior in the presence of Tf, Al was unable to compete with NTBI uptake, suggesting that both metals do not share the same alternative transport pathway. We propose that Al interference with TfR-mediated Fe incorporation might trigger the upregulation of NTBI uptake, an adaptation aimed at incorporating the essential metal required for cellular metabolism without allowing the simultaneous access of a potentially toxic metal.
There is evidence that anaemia is associated with aluminium (Al). We have already reported on the... more There is evidence that anaemia is associated with aluminium (Al). We have already reported on the sensitivity to Al, showed by erythroid cell populations of animals chronically exposed to the metal. In order to investigate whether Al could also affect human cells, experiments were carried out both on immature and mature human erythroid cells. Erythroid progenitors (CFU-E, colony-forming units-erythroid) concentrated from human peripheral blood were cultured in an Al-rich medium under erythropoietin stimulation and their development analysed. Human peripheral erythrocytes were aged in the presence of Al. Cells were examined using scanning electron microscopy, and membrane proteins analysed by polyacrylamide gel electrophoresis with sodium dodecyl sulphate and immunoblotting. The development of the Al-treated progenitors was 8750/6600–9200 CFU-E/106 cells, a significantly lower median value (P<0.05) than that showed by non-treated cells (12 300/11 200–20 700 CFU-E/106 cells). Erythrocyte morphological changes were induced by Al during the in vitro ageing. The cells lost their typical biconcave shape, turning into acanthocytes and stomatocytes. Simultaneously, an increased membrane protein breakdown compatible with band 3 degradation was detected. Besides, Al was found within the cells and attached to the membrane. The present in vitro results suggest that Al may disturb human erythropoiesis through combined effects on mature erythrocytes and cellular metabolism in late erythroid progenitors.
Aluminium (Al) affects erythropoiesis but the real mechanism of action is still unknown. Transfer... more Aluminium (Al) affects erythropoiesis but the real mechanism of action is still unknown. Transferrin receptors (TfR) in K562 cells are able to bind Tf, when carrying either iron (Fe) or Al, with similar affinity. Then, the aim of this work was to determine whether Al could interfere with the cellular Fe uptake and utilisation. K562 cells were induced to erythroid differentiation by either haemin (H) or sodium butyrate (B) and cultured with and without Al. The effect of Al on cellular Fe uptake, Fe incorporation to haem and cell differentiation was studied. H- and B-stimulated cells grown in the presence of 10 μM Al showed a reduction in the number of haemoglobinised cells (by 18% and 56%, respectively) and high amounts of Al content. Al2Tf inhibited both the 59Fe cellular uptake and its utilisation for haem synthesis. The removal of Al during the 59Fe pulse, after a previous incubation with the metal, allowed the cells to acquire Fe quantities in the normal range or even exceeding the amounts incorporated by the respective control cells. However, the Fe incorporated to haem could not reach control values in B-stimulated cells despite enough Fe acquisition was observed after removing Al. Present results suggest that Al might exert either reversible or irreversible effects on the haemoglobin synthesis depending on cellular conditions.
It has been suggested that aluminium (Al) has a deleterious effect on erythropoiesis. However, th... more It has been suggested that aluminium (Al) has a deleterious effect on erythropoiesis. However, there is still uncertainty as to its action mechanism. The present work was designed to determine how Al could affect the iron (Fe) metabolism in the human erythroleukaemia cell line K562. These cells, that express surface transferrin receptors (TfRs), were induced to erythroid differentiation by either haemin or hydroxyurea in 72 h cultures in media containing apotransferrin (apoTf). In the presence of aluminium citrate, the number of benzidine-positive cells decreased 18% when the cultures were induced by haemin, and 30% when hydroxyurea was the inducer. Cell viability was always unaffected. From competition assays, surface binding of 125I–Tf–Fe2 was found to be inversely related (p<0.05) to Tf–Al2 concentration (from 2.5 to 10 nM). The dissociation constants (Kd) of the binding reaction between TfRs and the ligands Tf–Fe2 and Tf–Al2 were calculated. Kd values of the same order of magnitude demonstrated that TfR has a similar affinity for Tf–Fe2 (Kd=1.75×10−9 M) and Tf–Al2 (Kd=1.37×10−9M). The number of surface TfRs, measured by kinetic 125I–Tf–Fe2 binding assays, was higher in induced cells cultured in the presence of Al. Nevertheless, in spite of the inhibition of cell haemoglobinisation observed, 59Fe incorporation values were not different from those measured in control cultures for 72 h. As a consequence, it can be suggested that cellular Fe utilisation, and not Fe uptake, might be the main metabolic pathway impaired by Al.
Anaemia has been associated with aluminium (Al) accumulation in plasma and/or bone tissue in pati... more Anaemia has been associated with aluminium (Al) accumulation in plasma and/or bone tissue in patients with chronic renal insufficiency. Nevertheless, in previous works, we have found shortened red-cell life span, increased osmotic resistance and inhibition of colony-forming units-erythroid (CFU-E) development in Al-overloaded rats with normal renal function. To elucidate further the action of Al on in vivo erythropoiesis, aluminium citrate was provided to Sprague Dawley rats (n=18) in the drinking water for 8 months. Significant decreases in haematocrit (38.8±4.29 versus 43.1±3.58%, p<0.05) and blood haemoglobin concentration (137±10.1 versus 148±8.5 g/l, p<0.05), reticulocytosis (1.8/1.3–4.2 versus 1.2/0.4–3.7%, p<0.05), and severe inhibition of CFU-E growth (670/120–950 versus 1530/810–2440 CFU-E/2×105 cells, p<0.005) were found. Anysocytosis, poikilocytosis and schistocytosis were detected in peripheral blood stained films. Scanning electron microscopy revealed the presence of erythrocytes with abnormal shape, including crenated and target cells. Aluminium was localised specially inside the schistocytes by EDAX analysis. Decreased haptoglobin concentration (107/83–127 versus 139/89–169 mg/l, p<0.05) supports the assumption of haemolytic nature of the anaemia. Rats were not iron depleted, as plasma iron concentration and total iron binding capacity were found in the range of control values, and sideroblasts and haemosiderin deposits were observed in bone marrow smears. Total 59Fe uptake and 59Fe incorporated to haem by the bone marrow cells were found decreased. In conclusion, the erythropoiesis impairment induced by Al may be a combined effect of direct action on circulating erythrocytes and interference with the cellular iron metabolism in erythroid progenitors.
To determine if there are differences in urinary glycosaminoglycan (GAG) concentrations, 43 stone... more To determine if there are differences in urinary glycosaminoglycan (GAG) concentrations, 43 stone-forming patients and 37 healthy control subjects of both sexes were studied. Urinary concentrations of calcium, magnesium, creatinine, uric acid and GAGs were determined. GAGs were measured by the Di Ferrante precipitation procedure followed by the Bitter and Muir reaction. Urinary GAG concentration and daily output were significantly
… and Alzheimers Disease. Elsevier, Amsterdam, cap, Jan 1, 2001
... Mechanisms Related to Cellular Dysfunction in Alzheimer&amp;amp;#x27;s Disease Alcira Nes... more ... Mechanisms Related to Cellular Dysfunction in Alzheimer&amp;amp;#x27;s Disease Alcira Nesse* and Graciela Garbossa Departamento de Quimica Biologica, Facultad de ... as a contributing factor to aggravate anaemia of end-stage renal disease—was first noticed in the Elliot and McDougall ...
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