Blockade of the in vitro effects of testosterone and erythropoietin on Cfu-E and Bfu-E proliferation by pretreatment of the donor rats with cyproterone and flutamide.

Erythropoietin is obligatory to support the terminal proliferation and differentiation of erythroid cells but it is not the only agent in modulating red cell production. Previously, we have shown that Testosterone enhances erythropoiesis, at least in part, by increasing renal erythropoietin production. Testosterone may also influence directly the behavior of the erythroid progenitor cells increasing erythroid stem cell proliferation. To gain further insight into the role of testosterone in regulation of erythropoiesis and its interactions with erythropoietin, we studied the effect of testosterone and erythropoietin, using clonal cultures of erythropietic progenitors, to observe CFU-E and late and early BFU-E colonies proliferation from bone marrow cells of donor rats pretreated for 2 days with the androgen antagonists cyproterone (10 mg/kg/day) and flutamide (160 mg/kg/day). Specific nuclear receptors for testosterone were demonstrated in marrow erythroid cells. Then, erythroid progenitors may come with their androgen receptors blocked by pretreatment. Cultures were prepared using the methylcellulose technique containing a standard dose of erythropoietin (250 mU/ml) or testosterone (10(-7)M). Results obtained demonstrate that testosterone produced a significant stimulation on CFU-E and BFU-E colony formation. A dose effect correlation was apparent. Testosterone enhances proliferation of late BFU-E more than CFU-E and produce only a slight augmentation of early BFU-E. As expected, erythropoietin markedly stimulate all erythroid colony growth, mainly CFU-E. The effects of testosterone were completely abolished in cultures from bone marrow cells of rats pretreated with cyproterone and flutamide. Activation of the specific androgen nuclear receptors in erythroid cells appears to be necessary for testosterone to develop the erythropoietic effect. Surprisingly, the effects of erythropoietin on erythroid colonies proliferation were also completely blocked by pretreatment with flutamide and partially blocked by pretreatment with cyproterone. Right now, we do not have a satisfactory explanation regarding inhibition of the effects of erythropoietin by pretreatment to marrow donor rats with the androgen antagonists. In conclusion, we postulate triggering late BFU-E cells, a marrow erythropoietin responsive cell population, into active cell cycle, as well as by increasing blood erythropoietin concentration.

Blockade of the in vitro effects of testosterone and erythropoietin on Cfu-E and Bfu-E proliferation by pretreatment of the donor rats with cyproterone and flutamide

Erythropoietin is obligatory to support the terminal proliferation and differentiation of erythroid cells but it is not the only agent in modulating red cell production. Previously, we have shown that Testosterone enhances erythropoiesis, at least in part, by increasing renal erythropoietin production. Testosterone may also influence directly the behavior of the erythroid progenitor cells increasing erythroid stem cell proliferation. To gain further insight into the role of testosterone in regulation of erythropoiesis and its interactions with erythropoietin, we studied the effect of testosterone and erythropoietin, using clonal cultures of erythropietic progenitors, to observe CFU-E and late and early BFU-E colonies proliferation from bone marrow cells of donor rats pretreated for 2 days with the androgen antagonists cyproterone (10 mg/Kg/day) and flutamide (160 mg/Kg/day). Specific nuclear receptors for testosterone were demonstrated in marrow erythroid cells. Then, erythroid progenitors may come with their androgen receptors blocked by pretreatment. Cultures were prepared using the methylcellulose technique containing a standard dose of erythropoietin (250 mu/ml) or testosterone (10(-7) M). Results obtained demonstrate that testosterone produced a significant stimulation on CFU-E and BFU-E colony formation. A dose effect correlation was apparent. Testosterone enhances proliferation of late BFU-E more than CFU-E and produce only a slight augmentation of early BFU-E. As expected, erythropoietin markedly stimulate all erythroid colony growth, mainly CFU-E. The effects of testosterone were completely abolished in cultures from bone marrow cells of rats pretreated with cyproterone and flutamide. Activation of the specific androgen nuclear receptors in erythroid cells appears to be necessary for testosterone to develop the erythropoietic effect. Surprisingly, the effects of erythropoietin on erythroid colonies proliferation were also completely blocked by pretreatment with flutamide and partially blocked by pretreatment with cyproterone. Right now, we do not have a satisfactory explanation regarding inhibition of the effects of erythropoietin by pretreatment to marrow donor rats with the androgen antagonists. In conclusion, we postulate triggering late BFU-E cells, a marrow erythropoietin responsive cell population, into active cell cycle, as well as by increasing blood erythropoietin concentration. (AU)

Blockade of the in vitro effects of testosterone and erythropoietin on Cfu-E and Bfu-E proliferation by pretreatment of the donor rats with cyproterone and flutamide

Erythropoietin is obligatory to support the terminal proliferation and differentiation of erythroid cells but it is not the only agent in modulating red cell production. Previously, we have shown that Testosterone enhances erythropoiesis, at least in part, by increasing renal erythropoietin production. Testosterone may also influence directly the behavior of the erythroid progenitor cells increasing erythroid stem cell proliferation. To gain further insight into the role of testosterone in regulation of erythropoiesis and its interactions with erythropoietin, we studied the effect of testosterone and erythropoietin, using clonal cultures of erythropietic progenitors, to observe CFU-E and late and early BFU-E colonies proliferation from bone marrow cells of donor rats pretreated for 2 days with the androgen antagonists cyproterone (10 mg/Kg/day) and flutamide (160 mg/Kg/day). Specific nuclear receptors for testosterone were demonstrated in marrow erythroid cells. Then, erythroid progenitors may come with their androgen receptors blocked by pretreatment. Cultures were prepared using the methylcellulose technique containing a standard dose of erythropoietin (250 mu/ml) or testosterone (10(-7) M). Results obtained demonstrate that testosterone produced a significant stimulation on CFU-E and BFU-E colony formation. A dose effect correlation was apparent. Testosterone enhances proliferation of late BFU-E more than CFU-E and produce only a slight augmentation of early BFU-E. As expected, erythropoietin markedly stimulate all erythroid colony growth, mainly CFU-E. The effects of testosterone were completely abolished in cultures from bone marrow cells of rats pretreated with cyproterone and flutamide. Activation of the specific androgen nuclear receptors in erythroid cells appears to be necessary for testosterone to develop the erythropoietic effect. Surprisingly, the effects of erythropoietin on erythroid colonies proliferation were also completely blocked by pretreatment with flutamide and partially blocked by pretreatment with cyproterone. Right now, we do not have a satisfactory explanation regarding inhibition of the effects of erythropoietin by pretreatment to marrow donor rats with the androgen antagonists. In conclusion, we postulate triggering late BFU-E cells, a marrow erythropoietin responsive cell population, into active cell cycle, as well as by increasing blood erythropoietin concentration.

Efectos adversos graves por inyección intramuscular de penicilina benzatínica / Severe adverse effects for intramuscular administration of benzathine penicillin

El artículo hace referencia a casos clínicos de efectos adversos graves en la administración intramuscular de Penicilina Benzatínica, aún bajo observancia de buena técnica de administración. Se destacan además aspectos relevantes del procedimiento de administración de medicamentos por esta vía (AU)

Efectos adversos graves por inyección intramuscular de penicilina benzatínica / Severe adverse effects for intramuscular administration of benzathine penicillin

El artículo hace referencia a casos clínicos de efectos adversos graves en la administración intramuscular de Penicilina Benzatínica, aún bajo observancia de buena técnica de administración. Se destacan además aspectos relevantes del procedimiento de administración de medicamentos por esta vía

Enhancement of erythroid colony growth by triiodothyronine in cell cultures from bone marrow of normal and anemic rats with chronic renal failure.

In order to make a contribution in clarifying the role of thyroid hormones on modulation of erythropoiesis and to gain a further insight on the effects of these hormones in the anemia of chronic renal failure (CRF), we studied the action of triiodo-1-thyronine (LT3) and DT3, a dextrorotary non-calorigenic isomer of T3 on late (CFU-E) and early (BFU-E) committed erythroid precursor cells from bone marrow of normal and anemic uremic rats. Cultures were prepared using the methylcellulose technique containing a standard dose (182 mU/ml) of erythropoietin (Ep), LT3 and DT3 in doses of 0.5 and 1.5 micrograms/ml. Thyroid hormones were added to cultures in the absence of Ep. Our results demonstrated that LT3 and DT3 produced a direct and significant stimulation of CFU-E formation and a moderate increase of BFU-E. A dose-correlation was apparent in cultures containing thyroid hormones. DT3 was somewhat less active than LT3. As expected, Ep also produced a significant increase in erythroid colony formation, mainly CFU-E. It is notheworthy that the effects of LT3, DT3 and Ep on erythroid colony growth were significantly higher in marrow cultures from anemic rats with CRF, indicating an increased proliferative cell kinetics of committed erythroid cells in response to these drugs.

Enhancement of erythroid colony growth by triiodothyronine in cell cultures from bone marrow of normal and anemic rats with chronic renal failure.

In order to make a contribution in clarifying the role of thyroid hormones on modulation of erythropoiesis and to gain a further insight on the effects of these hormones in the anemia of chronic renal failure (CRF), we studied the action of triiodo-1-thyronine (LT3) and DT3, a dextrorotary non-calorigenic isomer of T3 on late (CFU-E) and early (BFU-E) committed erythroid precursor cells from bone marrow of normal and anemic uremic rats. Cultures were prepared using the methylcellulose technique containing a standard dose (182 mU/ml) of erythropoietin (Ep), LT3 and DT3 in doses of 0.5 and 1.5 micrograms/ml. Thyroid hormones were added to cultures in the absence of Ep. Our results demonstrated that LT3 and DT3 produced a direct and significant stimulation of CFU-E formation and a moderate increase of BFU-E. A dose-correlation was apparent in cultures containing thyroid hormones. DT3 was somewhat less active than LT3. As expected, Ep also produced a significant increase in erythroid colony formation, mainly CFU-E. It is notheworthy that the effects of LT3, DT3 and Ep on erythroid colony growth were significantly higher in marrow cultures from anemic rats with CRF, indicating an increased proliferative cell kinetics of committed erythroid cells in response to these drugs.

Enhancement of erythroid colony growth by triiodothyronine in cell cultures from bone marrow of normal and anemic rats with chronic renal failure

Para contribuir a clarificar el rol de las hormonas tiroideas en la modulación de la eritropoyesis y profundizar en el conocimiento de los efectos de estas hormonas en la anemia de la insuficiencia renal crónica (CRF), estudiamos "in vitro" la acción de la l-triiodotironina (LT) y DT3, un isómero dextrorotatorio no-calorigénico de la T3 sobre precursores eritroides comprometidos maduros (CFU-E) y primitivos (BFU-E) de la médula ósea de ratas normales anémicas. Los cultivos fueron preparados usando la técnica de la metilcelulosa conteniendo una dosis standard de eritropoyetina (Ep) (182 mU/ml), LT3 y DT3 en dosis de o.5, y 1.5 ug/ml. Las hormonas tiroideas fueron agregadas a los cultivos en ausensia de Ep. Nuestros resultados demuestram que LT3 y DT3 producen una estimulación significativa y directa sobre la formación de CFU-E y un moderado incremento de BFU-E. Hubo una aparente relación dosis-dependiente en los cultivos que contienen las hormonas tiroideas. La DT3 fue menos activa que la LT3. Como se esperaba, la Ep produjo un significativo incremento en la formación de colonias eritroides, principalmente CFU-E. Los efectos de LT3, DT3 y Ep sobre el desarrollo de las colonias eritroides fue significativamente mayor en cultivos celulares de médula ósea de ratas anémicas con CRF, indicando la existencia de una cinética celular proliferativa más elevada en los progenitores eritroides comprometidos en respuesta a estas drogas. (AU)

Enhancement of erythroid colony growth by triiodothyronine in cell cultures from bone marrow of normal and anemic rats with chronic renal failure

Para contribuir a clarificar el rol de las hormonas tiroideas en la modulación de la eritropoyesis y profundizar en el conocimiento de los efectos de estas hormonas en la anemia de la insuficiencia renal crónica (CRF), estudiamos "in vitro" la acción de la l-triiodotironina (LT) y DT3, un isómero dextrorotatorio no-calorigénico de la T3 sobre precursores eritroides comprometidos maduros (CFU-E) y primitivos (BFU-E) de la médula ósea de ratas normales anémicas. Los cultivos fueron preparados usando la técnica de la metilcelulosa conteniendo una dosis standard de eritropoyetina (Ep) (182 mU/ml), LT3 y DT3 en dosis de o.5, y 1.5 ug/ml. Las hormonas tiroideas fueron agregadas a los cultivos en ausensia de Ep. Nuestros resultados demuestram que LT3 y DT3 producen una estimulación significativa y directa sobre la formación de CFU-E y un moderado incremento de BFU-E. Hubo una aparente relación dosis-dependiente en los cultivos que contienen las hormonas tiroideas. La DT3 fue menos activa que la LT3. Como se esperaba, la Ep produjo un significativo incremento en la formación de colonias eritroides, principalmente CFU-E. Los efectos de LT3, DT3 y Ep sobre el desarrollo de las colonias eritroides fue significativamente mayor en cultivos celulares de médula ósea de ratas anémicas con CRF, indicando la existencia de una cinética celular proliferativa más elevada en los progenitores eritroides comprometidos en respuesta a estas drogas.

A quantitative method for evaluating the effects of drugs on bone marrow cellularity using the same experimental animal. Quantification of the effects of a single dose of busulphan.

A method for quantifying the cellularity of rats bone marrow per unit of weight is described. Absolute numbers of each cell type per mg of bone marrow in the left and right femurs of the same experimental animal were determined at different times. In normal rats in which both femurs were studied simultaneously it was found that the absolute counts of each cell type per mg of bone marrow in the left and right femurs did not differ, nor were differences found in absolute numbers of marrow cells when the quantitative analyses from the left femurs were compared with those of the right femurs of the same animal, 10 and 20 days later. In order to test the validity of the present method for evaluating the effects of drugs on hematopoiesis, a single oral dose of busulphan (20 mg/kg), was administered to normal rats immediately after the marrow quantitative studies of the left femurs were performed. A marked and significant reduction in total nucleated cell was seen in marrows from the right femurs, 10 days later. Cellular effects were particularly pronounced on the myeloid line. Results presented here indicate that the quantitative study employed is a simple and useful method to evaluate the effects of drugs on hematopoiesis. The novelty of this method lies in: 1) its expression of cellularity on a per mg marrow basis, thereby avoiding possible misinterpretations of data which occur when results are expressed as percentages and 2) the analysis of contralateral femoral marrow specimens obtained from the same animal before and after drugs treatment. Therefore, each animal acts as its own control avoiding possible errors in the determination of drug-induced hematopoietic changes due to inter-animal variability.

A quantitative method for evaluating the effects of drugs on bone marrow cellularity using the same experimental animal. Quantification of the effects of a single dose of busulphan.

A method for quantifying the cellularity of rats bone marrow per unit of weight is described. Absolute numbers of each cell type per mg of bone marrow in the left and right femurs of the same experimental animal were determined at different times. In normal rats in which both femurs were studied simultaneously it was found that the absolute counts of each cell type per mg of bone marrow in the left and right femurs did not differ, nor were differences found in absolute numbers of marrow cells when the quantitative analyses from the left femurs were compared with those of the right femurs of the same animal, 10 and 20 days later. In order to test the validity of the present method for evaluating the effects of drugs on hematopoiesis, a single oral dose of busulphan (20 mg/kg), was administered to normal rats immediately after the marrow quantitative studies of the left femurs were performed. A marked and significant reduction in total nucleated cell was seen in marrows from the right femurs, 10 days later. Cellular effects were particularly pronounced on the myeloid line. Results presented here indicate that the quantitative study employed is a simple and useful method to evaluate the effects of drugs on hematopoiesis. The novelty of this method lies in: 1) its expression of cellularity on a per mg marrow basis, thereby avoiding possible misinterpretations of data which occur when results are expressed as percentages and 2) the analysis of contralateral femoral marrow specimens obtained from the same animal before and after drugs treatment. Therefore, each animal acts as its own control avoiding possible errors in the determination of drug-induced hematopoietic changes due to inter-animal variability.

Erythropoietic action of dexamethasone on the anemia associated with an experimental chronic renal failure.

Partially nephrectomized anemic uremic rats were injected with dexamethasone phosphate (10, 50 and 500 micrograms/kg/day), i.p., and erythropoietin (5 U/day), s.c., for 10 days. A marked and usually significant stimulatory effect on erythropoiesis was seen in all uremic animals treated. Administration of erythropoietin and dexamethasone produced a pronounced increment in hemoglobin, hematocrit and circulating reticulocytes. The increase in red blood cell production was also evident through the generally increased absolute numbers of nucleated erythroid cell precursors per milligram of bone marrow. The highest increases were seen in the erythropoietin treated uremic rats. A dose effect correlation was apparent in uremic rats receiving 3 different doses of dexamethasone. Dexamethasone may stimulate erythropoiesis in our anemic uremic rats through a previous augmentation of erythropoietin production in the residual renal mass. A synergistic permissive effect of dexamethasone increasing the sensitivity of the erythropoietin-responsive cells to erythropoietin in bone marrow is also quite possible.

Erythropoietic action of dexamethasone on the anemia associated with an experimental chronic renal failure.

Partially nephrectomized anemic uremic rats were injected with dexamethasone phosphate (10, 50 and 500 micrograms/kg/day), i.p., and erythropoietin (5 U/day), s.c., for 10 days. A marked and usually significant stimulatory effect on erythropoiesis was seen in all uremic animals treated. Administration of erythropoietin and dexamethasone produced a pronounced increment in hemoglobin, hematocrit and circulating reticulocytes. The increase in red blood cell production was also evident through the generally increased absolute numbers of nucleated erythroid cell precursors per milligram of bone marrow. The highest increases were seen in the erythropoietin treated uremic rats. A dose effect correlation was apparent in uremic rats receiving 3 different doses of dexamethasone. Dexamethasone may stimulate erythropoiesis in our anemic uremic rats through a previous augmentation of erythropoietin production in the residual renal mass. A synergistic permissive effect of dexamethasone increasing the sensitivity of the erythropoietin-responsive cells to erythropoietin in bone marrow is also quite possible.

Erythropoietic effects of triiodothyronine on the anemia of renal failure in rats: comparative studies with testosterone and erythropoietin.

A pronounced and significant stimulatory effect on erythropoiesis was observed in anemic uremic rats receiving either T3 (50 micrograms/kg/day) or Ep (7.5 and 15 U[units]/day) for ten days. A lack of erythropoietic response was seen after the administration of testosterone (5 mg/kg/day) for the same period of time. Renal failure and anemia were studied in partially nephrectomized rats that had received nephrotoxic doses of kanamycin (500 mg/kg/day). The marked increase in red blood cell production produced by T3 and Ep in anemic uremic rats was evident, not only from increased hemoglobin and hematocrit values in peripheral blood, but also from an elevated number of circulating reticulocytes and generally increased absolute counts of nucleated erythroid cells per milligram of bone marrow. The effects of T3 on erythropoiesis in anemic rats with renal insufficiency are in accordance with our previous report demonstrating the direct effect of thyroid hormones on marrow erythroid precursors. This effect can occur only when high levels of the free active forms of T3 are present in plasma, as can happen in the uremic rats receiving daily doses of T3. Since the possibility of producing large amounts of Ep for the treatment of the anemia associated with chronic renal failure is unlikely in the near future, utilization of T3, mainly compounds without calorigenic effects, may be a potential therapeutic alternative.