RESUMO
BACKGROUND: Iron sucrose (Fe-S) and low-molecular-weight iron dextran (Fe-D) have been used successfully in the treatment of anaemia in chronic kidney disease patients. However, some side effects, such as endothelial cell dysfunction have been reported. Mechanisms by which iron can induce endothelial cell damage have not been completely understood. This study was designed to examine the effect of Fe-S and Fe-D on bovine aortic endothelial cells in vitro. METHODS: Cell proliferation was determined by [3H] thymidine incorporation, cytotoxicity by lactate dehydrogenase, pro-Caspase-3 by immunoblotting; and Caspase-3 activity using a colorimetric assay. Expression of the apoptosis stress pathway proteins Bcl-2 and Bax and cycle arrest proteins p53 and p21WAF/CIP1 were examined by immunoblot. Cell apoptosis was tested by terminal deoxynucleotidyltransferase-mediated nick-end labelling (TUNEL) and DNA fragmentation. RESULTS: Both iron preparations inhibited cell proliferation. This effect was more important and occurred at lower concentrations in Fe-S than Fe-D cultured cells. Expression of p53 and p21WAF/CIP1 increased in cells incubated with Fe-S, but not with Fe-D. Bcl-2 expression was significantly down-regulated in cells incubated with Fe-S in comparison with Fe-D, while Bax expression was not modified by the iron compounds. Pro-Caspase-3 expression and Caspase-3 activity increased only in cells treated with Fe-S. Apoptosis was present in cells treated with Fe-S. CONCLUSIONS: Our results demonstrate that Fe-S exerts a greater inhibitory effect on endothelial cell proliferation than Fe-D. The mechanisms involved in this process may be related, at least in part, to over expression of proteins related to the cell cycle arrest and apoptosis stress pathway.
Assuntos
Apoptose/fisiologia , Células Endoteliais/metabolismo , Endotélio Vascular/metabolismo , Ferro/fisiologia , Estresse Fisiológico/metabolismo , Animais , Bovinos , Proliferação de Células , Células Cultivadas , Endotélio Vascular/citologia , Compostos Férricos/farmacologia , Óxido de Ferro Sacarado , Ácido Glucárico , Complexo Ferro-Dextran/farmacologia , Transdução de Sinais/fisiologiaRESUMO
The estrogen receptor (ER) gene has been considered as a candidate genetic marker for osteoporosis, and PvuII and XbaI polymorphisms of the ERalpha gene have been associated with low bone mineral density (BMD). We investigated whether ER polymorphism could predict the response of BMD in 28 postmenopausal women on hemodialysis with marked osteopenia or osteoporosis, randomized to receive raloxifene, a selective estrogen receptor modulator (SERM), or placebo for 1 year. BMD was assessed by dual X-ray absorptiometry and PvuII and XbaI restriction fragment-length polymorphism of the ER gene was determined using polymerase chain reaction. Baseline lumbar spine or femoral neck BMD parameters were not different between patients presenting either homozygous PP or xx when compared with heterozygous Pp or Xx genotypes. After 1 year, patients on raloxifene, presenting with PP or xx genotypes (but not those with Pp or Xx), showed a significantly higher mean lumbar spine BMD (0.942 +/- 0.18 vs. 0.925 +/- 0.17 g/cm2, p < .01) and lower serum pyridinoline (19.7 +/- 9.7 vs. 30.6 +/- 16.5 nmol/L, p < .02) when compared with baseline values. No changes were detected in the placebo-treated patients or in the femur neck sites. In conclusion, after 1 year on raloxifene, postmenopausal osteoporotic women on chronic hemodialysis, homozygous for the P or x (PP or xx) alleles of the ER, exhibited a better lumbar spine BMD response and decreased serum pyridinoline values when compared with heterozygous women (Pp or Xx), suggesting that ERalpha allelic variants may explain, at least in part, the different outcomes after treatment of osteoporosis with SERM.
Assuntos
Cloridrato de Raloxifeno/uso terapêutico , Receptores de Estrogênio/genética , Diálise Renal , Moduladores Seletivos de Receptor Estrogênico/uso terapêutico , Idoso , Densidade Óssea , Método Duplo-Cego , Feminino , Genótipo , Humanos , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , Polimorfismo Genético , Pós-MenopausaRESUMO
BACKGROUND: Premature amenorrhea and hypoestrogenism and lack of hormone replacement therapy after menopause have been frequently reported in uremic women on dialysis. Therefore, in addition to renal osteodystrophy, postmenopausal women on dialysis could be at risk of osteoporosis. In addition, these patients are at higher risk for hyperlipidemia, arteriosclerosis, and subsequent coronary heart disease and stroke. Recent evidence has suggested that hormone replacement therapy (HRT) in postmenopausal women could have several beneficial effects as well as potentially serious risks. Great efforts have been made to identify therapeutic alternatives that would have the benefits of estrogen on brain and bone without its adverse effects on breast and endometrium. In the present study, we evaluated the effect of raloxifene, a selective estrogen receptor modulator (SERM), on bone metabolism and serum lipids in postmenopausal women on chronic hemodialysis. METHODS: We performed a prospective, blind, placebo-controlled, and randomized study. Fifty postmenopausal women on chronic hemodialysis with proven severe osteopenia or osteoporosis by bone densitometry were selected. After a written informed consent, patients were randomized into two groups: 25 women on placebo and 25 women on the study drug, raloxifene hydrochloride, at a dose of 60 mg/day. In all patients, we performed a baseline bone mineral density (BMD) analysis and simultaneously evaluated different biochemical parameters, serum lipids (total low-density lipoprotein [LDL] and high-density lipoprotein [HDL] cholesterol and triglycerides) and serum markers of bone resorption (pyridinoline crosslinks). BMD was reassessed after 1 year of therapy. Bone resorption markers were determined every 3 months for 1 year. RESULTS: After 1 year on raloxifene therapy, lumbar spine BMD (trabecular bone) significantly improved, whereas femoral neck BMD (cortical bone) did not change significantly. No changes in BMD were observed at trabecular or cortical sites in the placebo group. Serum pyridinoline levels showed a significant decrease after 6 months on raloxifene that persisted thereafter. Low-density lipoprotein (LDL)-cholesterol decreased significantly in the raloxifene group with no changes in serum triglycerides, total cholesterol, or HDL cholesterol. No significant side effects were observed in the raloxifene group. CONCLUSION: The study demonstrates that after one year on raloxifene, postmenopausal women on hemodialysis have a significant increase in trabecular BMD, decrease in bone resorption markers and LDL-cholesterol values, suggesting that SERMs could constitute a therapeutic alternative to improve bone metabolism and control of hyperlipidemia in these patients. The possible long-term effects of raloxifene remain to be determined.
Assuntos
Doenças Ósseas Metabólicas/tratamento farmacológico , Osso e Ossos/metabolismo , Antagonistas de Estrogênios/administração & dosagem , Falência Renal Crônica/complicações , Cloridrato de Raloxifeno/administração & dosagem , Diálise Renal , Idoso , Densidade Óssea/efeitos dos fármacos , Doenças Ósseas Metabólicas/complicações , Doenças Ósseas Metabólicas/metabolismo , Feminino , Humanos , Falência Renal Crônica/metabolismo , Falência Renal Crônica/terapia , Lipídeos/sangue , Pessoa de Meia-Idade , Pós-Menopausa , Estudos ProspectivosRESUMO
Estudios previos de nuestro laboratorio han demonstrado una disminución del contenido mineral del hueso y una correlación entre la disminución del contenido mineral y la producción de distintas citoquinas que intervienen en el proceso de resorción ósea. Al mismo tiempo, observamos que el tratamiento a corto plazo con alendronato produce una disminución del calcio urinario en pacientes con hipercalciuria idiopática. En el presente estudio analizamos los efectos del alendronato a largo plazo (10 mg/día por un año) sobre el calcio y la hidroxiprolina urinaria y el contenido mineral óseo en 18 hipercalciúricos y 8 normocalciúricos con litiasis urinaria. Las características clínicas, así como la distribución por edades y sexo fue similar en ambos grupos. En calcio urinario disminuyó significativamente al final del primer mes y continuó bajo posteriormente (277 + 28, antes vs. 202 + 26 mg/g creatinina, después de 12 meses con alendronato, p<0.01). La hidroxiprolina urinaria disminuyó significativamente durante el estudio (125,5 + 32.1 vs. 39.66 + 17.5 mg/g creatinina, p<0.05). El calcio sérico, la filtración glomerular y el sodio urinario no se modificaron durante el estudio. La densidad mineral ósea en columna lumbar, determinada por densitometría por rayos X, se incremento significativamente el primer año de 1.162 + 0.231 a 1.197 + 0.248 g/cm2 (p<0.01). No se observaron cambios en la densidad mineral del cuello de fémur. Estos cambios se asociaron a una disminución en la transcripción del mRNA para IL-1 alpha, determinados por la reacción en cadena de polimerase (PCR), en células mononucleares no estimuladas. Los sujetos normocalciúricos no demostraron cambios significativos en la excreción urinaria de calcio. En resumen, los cambios observados en el calcio urinario y otros parámetros metabólicos óseos sugieren un papel importante del hueso en la fisiopatología de la hipercalciuria idiopática.
Assuntos
Humanos , Alendronato/uso terapêutico , Osso e Ossos/fisiologia , Densidade Óssea/fisiologia , Reabsorção Óssea , Cálcio/urina , Hidroxiprolina/urina , Absorciometria de Fóton , Osso e Ossos/metabolismo , Cálcio/metabolismo , Citocinas/fisiologia , Hidroxiprolina/metabolismo , Cálculos Urinários/complicaçõesRESUMO
Estudios previos de nuestro laboratorio han demonstrado una disminución del contenido mineral del hueso y una correlación entre la disminución del contenido mineral y la producción de distintas citoquinas que intervienen en el proceso de resorción ósea. Al mismo tiempo, observamos que el tratamiento a corto plazo con alendronato produce una disminución del calcio urinario en pacientes con hipercalciuria idiopática. En el presente estudio analizamos los efectos del alendronato a largo plazo (10 mg/día por un año) sobre el calcio y la hidroxiprolina urinaria y el contenido mineral óseo en 18 hipercalciúricos y 8 normocalciúricos con litiasis urinaria. Las características clínicas, así como la distribución por edades y sexo fue similar en ambos grupos. En calcio urinario disminuyó significativamente al final del primer mes y continuó bajo posteriormente (277 + 28, antes vs. 202 + 26 mg/g creatinina, después de 12 meses con alendronato, p<0.01). La hidroxiprolina urinaria disminuyó significativamente durante el estudio (125,5 + 32.1 vs. 39.66 + 17.5 mg/g creatinina, p<0.05). El calcio sérico, la filtración glomerular y el sodio urinario no se modificaron durante el estudio. La densidad mineral ósea en columna lumbar, determinada por densitometría por rayos X, se incremento significativamente el primer año de 1.162 + 0.231 a 1.197 + 0.248 g/cm2 (p<0.01). No se observaron cambios en la densidad mineral del cuello de fémur. Estos cambios se asociaron a una disminución en la transcripción del mRNA para IL-1 alpha, determinados por la reacción en cadena de polimerase (PCR), en células mononucleares no estimuladas. Los sujetos normocalciúricos no demostraron cambios significativos en la excreción urinaria de calcio. En resumen, los cambios observados en el calcio urinario y otros parámetros metabólicos óseos sugieren un papel importante del hueso en la fisiopatología de la hipercalciuria idiopática. (AU)