Biomedical subjects

B Cisneros

Publications and source records attributed to B Cisneros.

16 recordsLinked to original sources

PubMed2006

Association of the CT gene (CA) polymorphism with BMD in osteoporotic Mexican women.

Calcitonin (CT) plays a role in the pathogenesis of osteoporosis and genetic variations in or adjacent to the CT gene may be associated with loss of bone mineral density (BMD). The correlation between a dinucleotide (cytosine-adenine) repeat polymorphism at the CT locus and BMD was examined in 70 osteoporotic women, 70 non-osteoporotic women and 500 subjects from the Mexican population. The allele A and genotype AA frequencies were significantly higher in osteoporotic women than in non-osteoporotic women (60% vs 32%; p < 0.0001 and 41% vs 14%; p = 0.0007, respectively). Genotype AA was associated with the presence of osteoporosis [odds ratio 2.58; 95% confidence interval (CI); 1.62-4.12]. Likewise, the loss of lumbar BMD and T scores were related to the presence of allele A: subjects with a single A allele displayed lower values for lumbar BMD and T score (84.02% and -1.51, respectively) than those who do not present any A allele (89.61% and -0.88, respectively). Individuals with two alleles A showed the lowest lumbar BMD and T-score values (73.77% and -2.51, respectively). Analysis of potential confounder demonstrated that aging has a significant effect on osteoporosis development (odds ratio 1.1; 95% CI; 1.1052-1.152).

Adult↗

PubMed2003

Differential expression and subcellular distribution of dystrophin Dp71 isoforms during differentiation process.

Dp71 is the major product of the Duchenne muscular dystrophy gene in the brain. In order to study the function of Dp71 in the nervous system we examined the expression of Dp71 isoforms in PC12 rat pheochromocytoma cell line, a well-established system to study neuronal differentiation. We show by reverse transcriptase-polymerase chain reaction and Western blot assays that PC12 cells express two Dp71 isoforms. One isoform lacks exon 71 and the other isoform lacks exons 71 and 78 (Dp71d and Dp71f isoforms respectively). Nerve growth factor-induced neuronal differentiation of PC12 cells results in differential regulation of the expression and subcellular localization of Dp71 isoforms: a) the amount of Dp71f protein increases nine-fold in total extracts while Dp71d increases up to seven-fold in nuclear extracts; b) Dp71f relocates from the cytoplasm to neuritic processes, being prominent at varicosities and the growth cone; c) Dp71d relocates almost entirely to the nucleus and is detected to a lower extent in the cytoplasm and neuritic processes. Dp71f co-localizes with beta-dystroglycan and synaptophysin while Dp71d co-localizes with beta-dystroglycan in the nucleus. Dp71d accumulates at cell-cell contacts where Dp71f is absent. These results suggest that Dp71d and Dp71f associate with different subcellular complexes and therefore may have distinct functions in PC12 cells.

Animals↗

PubMed2001

[Papillomatous and nevus of the caruncle].

A 63-year-old male patient was operated of a single conjunctival papillomatous lesion located on the left caruncle. The curative tumoral excision was followed by its histological analysis. Histologically, the tumor associated an epithelial squamous papilloma with a subepithelial nevus, confirming a combination of two different lesions.

Conjunctiva↗

PubMed2000

Alternative splicing regulates the nuclear or cytoplasmic localization of dystrophin Dp71.

The subcellular distribution of Dp71 isoforms alternatively spliced for exon 71 and/or 78 was examined. The cDNA sequence of each variant was fused to the C-terminus of the green fluorescent protein and the constructs were transfected transiently in the cell lines HeLa, C2C12 and N1E-115. The subcellular distribution of the fused proteins was determined by confocal microscope analysis. The Dp71 isoform lacking the amino acids encoded by exons 71 and 78 was found exclusively in the cytoplasm whereas the variants containing the amino acids encoded by exon 71 and/or exon 78 show a predominant nuclear localization. The nuclear localization of Dp71 provides a new clue towards the establishment of its cellular function.

Active Transport, Cell Nucleus↗

PubMed2000

Expression and localization of utrophin in differentiating PC12 cells.

To ascertain the role of utrophin in cultured neuronal cells, we investigated its expression and distribution along the NGF-induced differentiation of PC12 cells grown on different substrata. Utrophin mRNA was measured by RT-PCR assay and utrophin protein was quantified by immunoblot analysis. The distribution of utrophin and beta-dystroglycan was analyzed by confocal microscopy. We demonstrate that utrophin protein was increased 4-fold during differentiation of cells grown laminin. Concomitant with this up-regulation, utrophin was enriched at the growth cones in differentiating cells, where it co-localizes with beta-dystroglycan. These data suggest the presence of a utrophin-beta-dystroglycan complex in PC12 cells that participates in the formation and/or stabilization of the growth cone-extracellular matrix adhesion.

Animals↗

PubMed2000

Lymphocytic choriomeningitis virus chorioretinitis mimicking ocular toxoplasmosis in two otherwise normal children.

PURPOSE: To report unilateral macular lesions, mimicking toxoplasmic scars, in two children with serological evidence for lymphocytic choriomeningitis virus infection. METHODS: Case reports. RESULTS: Patients were 4 and 5 years old, with negative toxoplasma serologies and no sign of rubella, cytomegalovirus, or herpes simplex infection (TORCH evaluation). Lymphocytic choriomeningitis virus infection was detected in both cases by enzyme-linked immunosorbent assay and confirmed by Western immunoblotting. The modes of infection were unknown; no history of symptomatic systemic lymphocytic choriomeningitis virus infection was reported, and lymphocytic choriomeningitis virus serologies were negative in the mothers of the patients. Neurological examinations and brain magnetic resonance imaging were normal. CONCLUSION: Our observations suggest that chorioretinal scars can be an isolated manifestation of lymphocytic choriomeningitis virus infection.

Animals↗

PubMed1999

Sp1 and AP2 transcription factors are required for the human fragile mental retardation promoter activity in SK-N-SH neuronal cells.

The promoter of the human fragile mental retardation gene (FMR1) was functionally analyzed in order to identify elements responsible for its regulation. Plasmids carrying the wild type or different deleted-promoter sequences driving the chloramphenicol acetyl transferase gene (CAT) were transiently transfected into the SK-N-SH cells and the CAT activity was assessed. Deletion studies suggested that major regulatory elements are present in a DNA region between positions -123 and -51. Gel mobility shift and footprinting assays using a DNA fragment encompassing that promoter region showed that SP1 and AP2 transcription factors could be involved in the functioning of the FMR1 promoter.

Cell Line↗

PubMed1997

Dystrophins in developing retina: Dp260 expression correlates with synaptic maturation.

Dystrophin, the protein altered in Duchenne muscular dystrophy (DMD), is necessary for normal retinal function and exists in several isoforms. We examined the expression of dystrophin and utrophin proteins and transcripts in the rat retina at different developmental stages using Western blots and semi-quantitative RT-PCR. Our results revealed the presence of utrophin (DRP1), G-utrophin and/or DRP2 and four dystrophin isoforms (Dp427, Dp260, Dp140, Dp71) in the normal adult rat retina. Only Dp260 showed a marked progressive increase with age at both protein and mRNA levels. This variation is consistent with the establishment of synaptic functions in the developing retina and suggests a key role for this apo-dystrophin in synaptogenesis.

Animals↗

PubMed1997

Pattern of deletions of the dystrophin gene in Mexican Duchenne/Becker muscular dystrophy patients: the use of new designed primers for the analysis of the major deletion "hot spot" region.

We have analyzed 59 unrelated Mexican Duchenne/Becker muscular dystrophy patients (DMD/BMD) using PCR analysis of the 2 prone deletion regions in the DMD gene. Thirty one (52%) of the patients had a deletion of one or several of the exons. Most of the alterations (87%) were clustered in exons 44-52, this being the highest percentage reported until now. In order to improve the molecular diagnosis in the Mexican population, we designed a new multiplex assay to PCR amplify exons 44-52. This assay allowed for the identification of a greater number of deletions in this region compared with the 9 and 5-plex assays previously described and to determine most of the deletion end boundaries. This is a reliable alternative for the initial screening of the DMD patients in the Mexican population.

Dystrophin↗

PubMed1997

Analysis of the (CAG)n repeat causing Huntington's disease in a Mexican population.

We investigated the allele distribution of the polymorphic (CAG)n repeat in the IT15 gene in 96 normal subjects from the Mexican population and 83 unrelated patients with Huntington's disease. Our results show that the size distributions of normal and affected alleles do not overlap. Normal alleles range from 13 to 32 triplets, with 18 being the most frequent allele, while HD alleles contain 37 to 76 repeats with 42 being the most frequent. One allele in the range of intermediate alleles was found (32 repeats) in a normal subject. The juvenile onset cases in this study are associated with an expansion greater than 49 repeats. In the available parent-offspring pairs, paternal alleles show instability with an expansion of 28 repeats in one case.

Adolescent↗

PubMed1996

Point mutations in a transcription terminator, lambda tI, that affect both transcription termination and RNA stability.

The terminator tI is located approx. 280 nucleotides beyond the int gene of bacteriophage lambda. Besides its role as a transcription terminator, tI may confer stability to the int message by protecting it from 3' exonucleolytic degradation. In order to study the role of the tI sequence in transcription termination and RNA stability, three different point mutations tI1, tI2, and tI3 were isolated and characterized. All the tI mutations map in the G + C-rich region of dyad symmetry in the terminator and decrease the transcriptional termination of tI in vivo from 99% for the wild type terminator to 81-93% as determined by galactokinase activity and in vitro from 80% for the wild type terminator to 8-12% using the E. coli RNA polymerase. Additionally, the tI mutations cause upstream transcript instability in vivo. This instability defect caused by tI mutations is compensated by the host mutant deficient in polynucleotide phosphorylase resulting in increased steady state levels of these mutant transcripts. The results show that the intact hairpin of tI is essential for efficient transcription termination and for maintaining mRNA stability by blocking the 3' to 5' exonucleolytic activity of polynucleotide phosphorylase.

Bacteriophage lambda↗

PubMed1996

Expression of dystrophin Dp71 during PC12 cell differentiation.

The expression of dystrophin-protein 71 (Dp71) was investigated during nerve growth factor (NGF) induced differentiation of PC12 cells. A semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay was designed to measure Dp71 mRNA, whereas the Dp71 protein amount was evaluated by immunoblot analysis using an anti-dystrophin monoclonal antibody. Comparison with control cultures showed that Dp71 mRNA and protein levels increased in parallel with NGF treatment peaking with increments of 60% and 1.4 times, respectively. The upregulation of Dp71 expression during PC12 cells differentiation point at PC12 cells as a suitable model for studying the function of Dp71 in neuronal cells.

Animals↗

PubMed1996

Carrier detection in Duchenne and Becker muscular dystrophy using dinucleotide repeat polymorphisms. A study in Mexican families.

In order to improve carrier detection of Duchenne and Becker muscular dystrophy, dinucleotide sequences repeats (CA) of introns 44, 45, 49 and 50 were used as well as two markers located at the 5' and 3' ends of the dystrophin gene. Haplotypes of the unaffected and affected persons of ten DMD/ BMD Mexican families were determined. Fifty eight females were studied, 30 of whom were at-risk STR haplotypes. Furthermore, it was possible to identify a recombination event in the dystrophin gene in one family, and a gonadal mosaicism was found in another family.

Genetic Carrier Screening↗

PubMed1993

Analysis of dystrophin gene deletions in patients from the Mexican population with Duchenne/Becker muscular dystrophy.

Forty unrelated Mexican patients with Duchenne/Becker muscular dystrophy were analyzed for intragenic DMD gene deletions, using the multiplex amplification of 15 deletion-prone exons described by Chamberlain et al. and Beggs et al. The percentage of deletions was 52.5%, and the majority of them (86.3%) were located at the hot spot deletion region which encompasses exons 44-55. This frequency is higher than that found in American and European populations. There were no correlations between deletion size, location and clinical severity.

Dystrophin↗

PubMedDate not supplied

Myotonic dystrophy protein kinase (DMPK) gene expression in lymphocytes of patients with myotonic dystrophy.

BACKGROUND: Myotonic dystrophy (DM) is an autosomal dominant neuromuscular disorder with defects in many tissues, including skeletal muscle myotonia, progressive myopathy, and abnormalities in heart, brain, and endocrine systems. It is associated with a trinucleotide repeat occurring in the 3' (UTR) untranslated region of the myotonic dystrophy protein kinase (DMPK) gene. Several studies have been carried out to determine DMPK gene expression in muscle and non-muscle tissues. METHODS: DMPK gene expression was determined in lymphocytes of adult-onset patients with DM and normal controls. To quantitate total locus expression as well as allele-specific mRNA levels, semiquantitative RT-PCR assay was used. Allele-specific expression was analyzed using a Bpm1 polymorphism located at exon 10 of the DMPK gene. RESULTS: In heterozygous patients with DM, we observed a fourfold difference between mRNA levels produced by the Bpm1-undigested allele (187 bp) compared to the Bpm1-digested allele (136 bp). By using (CTG) trinucleotide (with cytosine, thymine, and guanine) expansion polymorphism, it was shown that the down-regulated allele corresponds to the mutant allele. Interestingly, the reduction in the mutant allele-transcript levels is compensated by an increase of the wild-type allele, yielding no significant differences in total locus mRNA amount between patients and normal individuals. CONCLUSIONS: These results suggest that the expression of the two alleles at the DMPK locus in lymphocytes is coordinated. The reduction in mutant-allele transcript levels is compensated by an increase in wild-type allele mRNA levels.

Gene Expression Regulation, Enzymologic↗

PubMedDate not supplied

[Restoration of transcription antitermination of N- bacteriophages in Escherichia coli with a mutant RNA polymerase].

The N protein of bacteriophage lambda modifies Escherichia coli RNA polymerase in such a way that it transcribes through termination signals, in a process called antitermination. In general N-mutants are not able to perform transcription antitermination. In this paper we report the suppression of N7 and Nmar3 mutations by Escherichia coli ron-lon strain. The lon mutation causes the N protein half-life to raise, suggesting that excess of N7 fragment or Nmar3 protein overcome the defect in antitermination. Under these conditions the lambda N-phages produced a titer similar to lambda wild type, although the plaques were smaller. These observations highlight the relevance of N half life in the regulation of transcription antitermination.

ATP-Dependent Proteases↗