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Biomedical subjects

Fernando López-Barea

Publications and source records attributed to Fernando López-Barea.

6 recordsLinked to original sources
PubMed2006

The orphan nuclear receptor DAX1 is up-regulated by the EWS/FLI1 oncoprotein and is highly expressed in Ewing tumors.

The Ewing family of tumors harbors chromosomal translocations that join the N-terminal region of the EWS gene with the C-terminal region of several transcription factors of the ETS family, mainly FLI1, resulting in chimeric transcription factors that play a pivotal role in the pathogenesis of Ewing tumors. To identify downstream targets of the EWS/FLI1 fusion protein, we established 293 cells expressing constitutively either the chimeric EWS/FLI1 or wild type FLI1 proteins and used cDNA arrays to identify genes differentially regulated by EWS/FLI1. DAX1 (NR0B1), an unusual orphan nuclear receptor involved in gonadal development, sex determination and steroidogenesis, showed a consistent up-regulation by EWS/FLI1 oncoprotein, but not by wild type FLI1. Specific induction of DAX1 by EWS/FLI1 was confirmed in two independent cell systems with inducible expression of EWS/FLI1. We also analyzed the expression of DAX1 in Ewing tumors and derived cell lines, as well as in other nonrelated small round cell tumors. DAX1 was expressed in all Ewing tumor specimens analyzed, and in seven out of eight Ewing tumor cell lines, but not in any neuroblastoma or embryonal rhabdomyosarcoma. Furthermore, silencing of EWS/FLI1 by RNA interference in a Ewing tumor cell line markedly reduced the levels of DAX1 mRNA and protein, confirming that DAX1 up-regulation is dependent upon EWS/FLI1 expression. The high levels of DAX1 found in Ewing tumors and its potent transcriptional repressor activity suggest that the oncogenic effect of EWS/FLI1 may be mediated, at least in part, by the up-regulation of DAX1 expression.

Cell Line↗
PubMed2006

Serum albumin levels, an additional factor implicated in hyperparathyroidism outcome in peritoneal dialysis: a prospective study with paired bone biopsies.

Renal osteodystrophy encompasses several histologic subtypes, all of which can undergo change over time. In peritoneal dialysis (PD) patients, we studied bone histology and the factors influencing any changes over 1 year In 44 PD patients, we collected two paired bone biopsies (at baseline and after 12 months) and biochemical and treatment data (at baseline and every 3 months). Of the 44 original patients, 24 completed the study. Of these 24 patients, 19 were initially diagnosed with adynamic bone lesion (ABL). After 1 year, 12 still had ABL; the other 7 had changed to high turnover bone lesion (HTBL). Another 5 patients were initially diagnosed with HTBL. Among these, 4 still had HTBL at 1 year; 1 had changed to ABL. In patients who changed to HTBL from ABL, serum albumin had increased to 4.2 +/- 0.3 g/dL at month 12 from 3.7 +/- 0.4 g/dL at baseline (p < 0.05). In patients who still had ABL, serum albumin did not change. Additionally, the percentage increase in serum albumin over the study was higher in HTBL patients than in ABL patients (0.1408 +/- 0.139 g/dL vs. -0.0076 +/- 0.113 g/dL, p = 0.009). A lower likelihood of diabetes (p = 0.033) and a higher serum albumin [area under the curve: 0.822; 95% confidence interval (CI): 0.651 to 0.993] identified a HTBL diagnosis at 12 months. Older age increased the probability of changing to ABL (OR: 1.2935; 95% CI: 1.03 to 1.67; p= 0.02). Bone lesions can change over time, and this change is associated with age, diabetes, and serum albumin. A change to HTBL was associated with improvement in serum albumin. Protein status is possibly a factor influencing bone lesion outcome.

Biopsy, Needle↗
PubMed2004

Low vs standard calcium dialysate in peritoneal dialysis: differences in treatment, biochemistry and bone histomorphometry. A randomized multicentre study.

BACKGROUND: In patients undergoing peritoneal dialysis (PD), low-calcium dialysate (LCD) has been proposed as the first choice for a better control of renal osteodystrophy. Our aim was to compare the effects on bone metabolism of LCD (calcium: 1.25 mmol/l) with that of a standard calcium dialysate (SCD; calcium: 1.75 mmol/l). METHODS: Forty-four PD patients were randomized to receive LCD or continue on SCD for a period of 12 months. Bone biopsies were taken at baseline and at 12 months. Biochemical data and treatment were evaluated every 3 months. RESULTS: Twenty-four patients completed the study. In the SCD group (n = 10), nine out of the 10 patients were initially diagnosed with adynamic bone lesion (ABL). After 1 year, six continued having ABL and three patients moved to high-turnover bone lesion (HTBL). The other patient, initially diagnosed with HTBL, changed to ABL. In the LCD group (n = 14), 10 patients were initially diagnosed with ABL. At 1 year, six of them continued having ABL and four patients changed to HTBL. Four patients were initially diagnosed with HTBL and did not change. Comparison between LCD and SCD groups showed an increase in serum parathyroid hormone (PTH) levels starting at month 3 and a higher intake of calcium salts in the former group (P<0.01). Serum calcium, phosphate levels and bone histological outcome did not differ between the two groups. CONCLUSIONS: LCD use for 1 year was associated with an increase in PTH levels, but did not lead to histological changes different from those observed in SCD group. The LCD solution allowed a higher oral intake of calcium salts with a satisfactory control of the serum Calcium-Phosphorus product.

Bone and Bones↗
PubMed2003

Membranous lipodystrophy. Case report and review of the literature.

Membranous lipodystrophy (ML) is a rare hereditary disorder of adipose tissue characterized by polycystic bone lesions and progressive dementia. We describe the case of a 36-year-old woman with mechanical bone pain. Routine laboratory analyses revealed only a type IV hyperlipoproteinemia and hyperexcretion of urinary calcium. Roentgenograms of short and long bones showed symmetrical, well-defined, non-expansile cystic lesions. Bone biopsy found a yellow lipid-like substance in the osteolytic lesions and histopathological studies were non-specific. Neuropsychiatric examination, including cranial computerized tomography (CT), was found to be normal. According to clinical, analytical, radiological and histological findings ML was the diagnosis. No previous cases of ML have been reported in our country as we review the literature concerning this disease.

Adult↗
PubMed2001

Radiation-induced osteochondroma of the T4 vertebra causing spinal cord compression.

A case of a radiation-induced osteochondroma arising from the vertebral body of T4 in an 18-year-old man is reported. The patient presented with a history of progressive left lower extremity weakness. At 7 years of age, he had undergone resection of a cerebellar medulloblastoma and received adjunctive craniospinal irradiation and systemic chemotherapy. Both CT and MR imaging revealed an extradural mass contiguous with the posteroinferior endplate of the T4 vertebral body. This case indicates that radiation-induced osteochondroma should be considered in the differential diagnosis of patients with symptoms of myelopathy or nerve root compression and a history of radiation therapy involving the spine in childhood.

Adult↗