RESUMEN
UNLABELLED: We demonstrate histological evidence for hyperparathyroidism in patients with gastrectomy. This is, at least in part, explained by impaired calcium absorption, resulting in mineralization defects and secondary hyperparathyroidism. Additionally, we demonstrate improved bone mineralization in patients with gastrectomy after gluconate therapy and showed the effectiveness of calcium gluconate over carbonate to balance impaired calcium hemostasis in mice. INTRODUCTION: Gastrectomy and hypochlorhydria due to long-term proton pump inhibitor therapy are associated with increased fracture risk because of intestinal calcium malabsorption. Hence, our objectives were to histologically investigate bone metabolism in patients with gastrectomy and to analyze the impact of calcium gluconate supplementation on skeletal integrity in the setting of impaired gastric acidification. METHODS: Undecalcified bone biopsies of 26 gastrectomized individuals were histologically analyzed. In the clinical setting, we retrospectively identified 5 gastrectomized patients with sufficient vitamin D level, who were additionally supplemented with calcium gluconate and had a real bone mineral density (aBMD) follow-up assessments. A mouse model of achlorhydria (ATP4b-/-) was used to compare the effect of calcium gluconate and calcium carbonate supplementation on bone metabolism. RESULTS: Biopsies from gastrectomized individuals showed significantly increased osteoid, osteoclast, and osteoblast indices and fibroosteoclasia (p < 0.05) as well as impaired calcium distribution in mineralized bone matrix compared to healthy controls. Five gastrectomized patients with sufficient vitamin D level demonstrated a significant increase in aBMD after a treatment with calcium gluconate alone for at least 6 months (p < 0.05). Calcium gluconate was superior to calcium carbonate in maintaining calcium metabolism in a mouse model of achlorhydria. CONCLUSION: Gastrectomy is associated with severe osteomalacia, marrow fibrosis, and impaired calcium distribution within the mineralized matrix. We show that calcium gluconate supplementation can increase bone mineral density in gastrectomized individuals and performs superior to calcium carbonate in restoring calcium/skeletal homoeostasis in a mouse model of achlorhydria.
Asunto(s)
Gluconato de Calcio/uso terapéutico , Gastrectomía/efectos adversos , Hiperparatiroidismo Secundario/tratamiento farmacológico , Osteoporosis/tratamiento farmacológico , Aclorhidria/tratamiento farmacológico , Anciano , Animales , Biopsia , Densidad Ósea/efectos de los fármacos , Calcio/metabolismo , Gluconato de Calcio/farmacología , Carbamatos/uso terapéutico , Suplementos Dietéticos , Modelos Animales de Enfermedad , Evaluación Preclínica de Medicamentos/métodos , Femenino , Homeostasis/efectos de los fármacos , Humanos , Hiperparatiroidismo Secundario/etiología , Hiperparatiroidismo Secundario/metabolismo , Ilion/patología , Masculino , Ratones Noqueados , Persona de Mediana Edad , Osteoblastos/patología , Osteoclastos/patología , Osteoporosis/etiología , Osteoporosis/patología , Osteoporosis/fisiopatología , Estudios RetrospectivosRESUMEN
A yeast two-hybrid screen was performed to find new factors involved in pre-mRNA splicing. Using SC35 as a bait, we isolated a human cDNA bearing high homology to the Drosophila transformer-2 (TRA-2) protein. This cDNA was named htra2-beta1. htra2-beta1 is a nuclear protein that colocalizes with SC35 in a speckled pattern. It interacts with several SR proteins tested in yeast. A second form named htra2-beta2 is generated by alternative splicing. This isoform gives rise to a truncated protein without an SR domain. Both isoforms are evenly distributed throughout adult rat tissue. The ratio of these two isoforms changes after stimulation of primary human T-cell and primary rat spleen cell cultures, indicating that alternative splicing is involved in regulation of htra2-beta activity.
Asunto(s)
Empalme Alternativo , Proteínas de Drosophila , Ribonucleoproteínas/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Línea Celular , Clonación Molecular , Drosophila/genética , Humanos , Datos de Secuencia Molecular , Ratas , Saccharomyces cerevisiae/genética , Homología de Secuencia de Ácido NucleicoRESUMEN
The chromosome constitutions of black-melanotic (Ma), brown-melanotic (MI), and amelanotic (Ab) melanomas of the Syrian hamster were compared. The MI and Ab melanomas arose through a spontaneous phenotypic alteration of the Ma tumor. All three variants differ in their growth rates, with MI showing the slowest, Ab the fastest, and Ma intermediate growth rate. Cytogenetic examination revealed that each tumor line shows a distinct karyotype. The Ma tumor is near-diploid, whereas, Ab and MI tumors are hypertriploid and near-tetraploid, respectively. Each tumor line shows a unique set of marker chromosomes, though some markers are shared by two different tumor lines. No single marker chromosome was common for all three melanoma variants. We conclude that the spontaneous phenotypic variation of transplantable hamster melanomas is associated with profound changes in the chromosome constitution of the neoplastic cells. The general direction of these changes is toward increased ploidy and increased complexity of the structural abnormalities.