PubMed Health⌕ Search

Biomedical subjects

C Orellana

Publications and source records attributed to C Orellana.

At least 19 recordsLinked to original sources
PubMed2006

Recombinant X chromosome in a prenatal diagnosis.

The prenatal cytogenetic study of an amniotic fluid sample of a 39-year-old female showed one X chromosome with a fragment of extra material in the short arm. The G-band pattern suggested that the extra material could be the long arm of an X chromosome. Several complementary studies were performed in order to better clarify the origin of the material. These studies included parental karyotypes, microsatellite typing and comparative genomic hybridization (CGH). The results obtained allowed us to conclude that the derivative chromosome arose de novo as a recombinant X chromosome with duplication of Xq and partial deletion of Xp. Once informed, the parents decided to continue with the pregnancy, after which a healthy girl was born with no apparent disorders.

Adult↗
PubMed2004

Minimal residual disease in neuroblastoma: to GAGE or not to GAGE.

We assessed the utility of GAGE gene expression as a marker of minimal residual disease (MRD) in neuroblastoma. The GAGE gene family shows a high degree of homology (>90%), clustering into two subgroups. GAGE-1, -2, and -8 form one subset, almost identical among themselves, while GAGE-3 to -7 constitute the other subset. The entire GAGE family (GAGE-1-8) was studied by RT-PCR followed by Southern blotting to increase both the sensitivity and specificity of the technique. Surprisingly, expression of GAGE was detected in 59% of peripheral blood samples from normal controls (20/35) as well as in a similar proportion from neuroblastoma patients with localized disease (stages 1 and 2). The study of GAGE-1, -2, and -8 with specific primers lowered this percentage to 28% (10/35), of which only two (6%) showed a high level of expression (directly visualized after RT-PCR). We conclude that GAGE genes can show a variable, usually low level of illegitimate expression in normal blood cells, and therefore their use as MRD markers should be taken with caution.

Antigens, Neoplasm↗
PubMed2003

Intronic L1 insertion and F268S, novel mutations in RPS6KA3 (RSK2) causing Coffin-Lowry syndrome.

Two novel mutations of the ribosomal S6 kinase 2 gene (also known as RSK2) have been identified in two unrelated patients with Coffin-Lowry syndrome. The first mutation consists of a de novo insertion of a 5'-truncated LINE-1 element at position -8 of intron 3, which leads to a skipping of exon 4, leading to a shift of the reading frame and a premature stop codon. The L1 fragment (2800 bp) showed a rearrangement with a small deletion, a partial inversion of the ORF 2, flanked by short direct repeats which duplicate the acceptor splice site. However, cDNA analysis of the patient shows that both sites are apparently not functional. The second family showed the nucleotide change 803T>C in exon 10, resulting in the F268S mutation. This mutation was detected in two monozygotic twin patients and in their mother, who was mildly affected. The patients fulfill the clinical criteria of the syndrome, and therefore the mutation provides further support for the importance of phenylalanine at position 268, which is highly conserved in the protein kinase domain of many serine-threonine protein kinases.

Adult↗
PubMed2001

Localization of non-specific X-linked mental retardation gene (MRX73) to Xp22.2.

Clinical and molecular studies are reported on a family (MRX73) of five males with non-specific X-linked mental retardation (XLMR). A total of 33 microsatellite and RFLP markers was typed. The gene for this XLMR condition was been linked to DXS1195, with a lod score of 2.36 at theta = 0. The haplotype and multipoint linkage analyses suggest localization of the MRX73 locus to an interval of 2 cM defined by markers DXS8019 and DXS365, in Xp22.2. This interval contains the gene of Coffin-Lowry syndrome (RSK2), where a missense mutation has been associated with a form of non-specific mental retardation. Therefore, a search for RSK2 mutations was performed in the MRX73 family, but no causal mutation was found. We hypothesize that another unidentified XLMR gene is located near RSK2.

Chromosome Mapping↗
PubMed2001

Trisomy rescue by postzygotic unbalanced (X;14) translocation in a girl with dysmorphic features.

In this report we present the clinical features and molecular and cytogenetic findings in a female with partial trisomy 14q. Molecular and cytogenetic studies allowed us to determine that the extra 14q material (of paternal origin) was translocated postzygotically onto the maternal X chromosome. Consequently, only the derivative X chromosome was inactivated, although inactivation apparently did not spread over the entire chromosome 14q. This partial inactivation makes the present case unusual, giving rise to phenotypic features absent in other patients with partial trisomy 14q, typically restricted to the distal part of the chromosome.

Blotting, Southern↗
PubMed1999

[Multiple endocrine neoplasia type 1: genetic study of a large family].

Multiple endocrine neoplasia syndrome type 1 (MEN-1) is an inherited disorder characterised by the predisposition of the cells from parathyroid glands, endocrine pancreas and adenohypophysis to develop neoplasms. We report the genetic study of an extended family with at least 8 affected patients and 10 putative carriers of a mutation in MEN-1 gene. One intragenic (Asp418 GAC-->GAT), and five flanking markers were characterised in the family by PCR amplification and polyachrylamide gel electrophoresis. Association of the disease to MEN-1 gene was confirmed for this family: all the affected members show a haplotype in common. Three patients at risk were diagnosed as non-carriers, since they have not inherited that haplotype. The remaining seven members, presymptomatic carriers, are included in a follow-up protocol. The genetic study of families segregating MEN-1 syndrome are useful in avoiding indiscriminate follow-up determinations to those members who have not received the genetic predisposition to develop any of the manifestations of the syndrome. Segregation analysis with linked markers is useful, under certain circumstances, to perform such type of studies.

Biomarkers, Tumor↗
PubMed1999

Idiopathic hypoparathyroidism associated with adult rheumatoid arthritis.

A 48-year-old female patient with adult onset idiopathic hypoparathyroidism diagnosed at the age of 28 years developed a typical seropositive rheumatoid arthritis (RA) at 46 years of age after several years of evolution of a palindromic rheumatism. Only one case of an association between idiopathic hypoparathyroidism and RA has been described in the medical literature. Autoimmunity seems to play a pivotal role in the aetiopathogenesis of both diseases, and could explain the nature of this association; nevertheless, a chance association could not be excluded.

Absorptiometry, Photon↗
PubMed1998

Pediatric brain tumors: loss of heterozygosity at 17p and TP53 gene mutations.

Cytogenetic and molecular analyses of primitive neuroectodermal tumors (PNETs) of the central nervous system (CNS) have demonstrated material losses of 17p, the region that contains the TP53 gene, as the most frequent abnormality. Mutations in the TP53 gene are, however, very rare in these tumors. These findings strongly suggest that another, as yet unidentified, gene on 17p may be involved. We performed a search for loss of heterozygosity (LOH) on 17p by microsatellite markers on 26 childhood CNS tumors as well as TP53 gene mutations (exons 5-8) by single-strand conformational polymorphism analysis on 41 pediatric brain tumor samples of distinct histologic types. LOH was detected in 10 cases: 7 PNET, 2 astrocytomas, and 1 glioblastoma multiforme. In 4 of the PNETs the losses were limited to more distal markers. On the other hand, TP53 mutations were detected in 6 of 41 samples studied. Our results not only confirm the low penetrance of the TP53 gene on pediatric CNS tumors, but also provide further evidence of a putative tumor suppressor gene distal to TP53, between markers (D17S938, D17S926) and 17pter, specifically taking part in the development of PNET.

Adolescent↗
PubMed1998

A novel TP53 germ-line mutation identified in a girl with a primitive neuroectodermal tumor and her father.

A search of TP53 mutations was undertaken in a series of 51 pediatric brain tumors. The only germ-line mutation was detected in a 9-year-old girl with a PNET. Her family history was unremarkable for neoplastic disease, except for the paternal grandfather, who died of a gallbladder carcinoma at an advanced age. The mutation was a thymine deletion at the first base of codon 241, leading to termination codon at position 246 that has not previously been reported. This mutation was found to be inherited from the proband's father, who was healthy at age 40. In the tumoral sample, loss of heterozygosity in several 17p markers was found, the only TP53 allele preserved in the tumor was the mutated one. The presence of two short tandem repeats and two different palindromic sequences spanning the deletion lead us to propose the predisposition of this region to forming a complex secondary structure during replication. Consequently, it could have facilitated the present deletion. Furthermore, six other short deletions affecting--partially or totally--the region implicated in the folding model that we propose have been described in the literature. These findings confirm that this sequence represents a hotspot of deletion in the TP53 gene.

Child↗
PubMed1997

Spondyloarthropathy presenting as a polymyalgia rheumatica-like syndrome.

Two female patients, aged 57 and 58 year-old presented with pain and stiffness in shoulder and/or pelvic girdles and a high ESR, suggesting polymyalgia rheumatica (PMR). The lack of response to low dose of steroids prompted us to reconsider this diagnosis and, after a careful evaluation and taking into account past clinical history, a final diagnosis of spondyloarthropathy (SpA) was made. The clinical spectrum of late SpA is heterogeneous, and in some instances may present as a polymyalgia-like syndrome.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1997

Secondary amyloidosis in ankylosing spondylitis. A systematic survey of 137 patients using abdominal fat aspiration.

OBJECTIVE: To assess the frequency and clinical significance of amyloid deposits in abdominal fat in patients with ankylosing spondylitis (AS). METHODS: Abdominal subcutaneous fat aspiration (ASFA) by fine needle was performed in 137 unselected patients with AS of more than 5 years of disease evolution. A followup study was done of patients with amyloidosis in the abdominal fat (ASFA positive test) to evaluate the development of clinical amyloidosis. RESULTS: In 10 (9M/1F) patients with AS, the ASFA revealed amyloid deposits (prevalence of 7%). Patients with AS and an ASFA+ test were older and had more active and severe disease than those without AS. Only 2 ASFA positive test patients had clinical amyloidosis at the time of the test. After a followup period of 2-10 yrs (mean 5.4 +/- 3.2 yrs), 3 more patients developed symptomatology due to amyloidosis. All 5 patients with clinical amyloidosis showed nephropathy, and proteinuria was found in each. The remaining patients did not develop clinical amyloidosis during followup. CONCLUSION: Amyloid deposits in abdominal fat are not a rare finding in AS. A significant proportion of these patients do not develop clinical amyloidosis after a followup of several years. Thus, an ASFA + test in patients with AS is not always associated with a poor prognosis at least in the short term, although longer followup is required.

Adipose Tissue↗
PubMed1996

The activity of microcin E492 from Klebsiella pneumoniae is regulated by a microcin antagonist.

Microcin E492 is a polypeptide antibiotic that is produced and excreted by Klebsiella pneumoniae. Different growth conditions of the producer strain affect microcin activity. The production of a microcin antagonist is responsible for the changes in microcin activity. The microcin antagonist is induced when cells are iron-deprived, resulting in a low microcin activity. The microcin antagonist was purified using a procedure developed for the isolation of a catechol-type siderophore, and its activity was titrated using purified microcin. The inhibitory effect of the microcin antagonist is not observed when this compound is forming a complex with iron. The same inhibitory effect on microcin activity was obtained using purified enterochelin from Escherichia coli. The microcin antagonist was identified as enterochelin through thin-layer chromatography.

Anti-Bacterial Agents↗