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Biomedical subjects

C Oliveira

Publications and source records attributed to C Oliveira.

At least 19 recordsLinked to original sources
PubMed2007

Prenatal sonographic diagnosis of a rare Cantrell's pentalogy variant with associated open neural tube defect - a case report.

Cantrell's pentalogy is a very rare congenital anomaly. The hallmark of this condition is the presence of ectopia cordis and an abdominal wall defect. Its association with craniorachischisis is even more infrequent with just a few cases reported in the literature. The authors describe a case of a prenatal ultrasound diagnosis of Cantrell's pentalogy with posterior encephalocele and spinal dysraphism associated.

Abdominal Wall↗
PubMed2006

Axial length and optic disc size in normal eyes.

AIM: To investigate the relationship between optic disc area and axial length in normal eyes of white and black people. METHODS: Consecutive eligible normal subjects were enrolled. Ocular biometry was obtained using A-scan ultrasonography, and reliable images of the optic disc were obtained using a confocal scanning laser ophthalmoscope. The relationship between optic disc area and axial length was assessed using univariate and multivariate models. RESULTS: 281 eyes of 281 subjects were enrolled. Black subjects (n = 157) had significantly larger discs (mean (SD) disc area, 2.12 (0.5) mm(2)) than white subjects (n = 124; 1.97 (0.6) mm(2); t test, p = 0.02). Optic disc area increased with axial length (Pearson's correlation coefficient, r = 0.13, p<0.035) for the entire study population. Multivariate regression models including race, disc area and axial length showed that a significant but weak linear relationship exists between axial length and disc area (partial correlation coefficient 0.14; p<0.024), and with race and disc area (partial correlation coefficient 0.19; p<0.017) when adjusted for the effects of other terms in the model. CONCLUSION: Increased disc area is associated with longer axial length measurements and African ancestry. This may have implications for pathophysiology and risk assessment of glaucoma.

Adolescent↗
PubMed2006

KRAS and BRAF oncogenic mutations in MSS colorectal carcinoma progression.

In sporadic colorectal cancer (CRC), KRAS are alternative to BRAF mutations and occur, respectively, in 30 and 10% of cases. Few reports addressed the association between KRAS-BRAF mutations and tumour progression specifically in sporadic microsatellite-stable (MSS) CRC. We screened KRAS and BRAF in 250 MSS primary CRC and 45 lymph node (LN) metastases and analysed the pathological features of the cases to understand the involvement of KRAS-BRAF activation in progression and metastasis. Forty-five per cent of primary MSS CRCs carried mutations in at least one of these genes and mutations were associated with wall invasion (P=0.02), presence and number of LN metastases (P=0.02 and P=0.03, respectively), distant metastases (P=0.004) and advanced stage (P=0.01). We demonstrated that KRAS and BRAF are alternative events in Tis and T1 MSS CRC and, KRAS rather than BRAF mutations, contributed to the progression of MSS CRC. The frequency of KRAS and/or BRAF mutations was higher in LN metastases than in primary carcinomas (P=0.0002). Mutated LN metastases displayed KRAS associated or not with BRAF mutations. BRAF mutations were never present as a single event. Concomitant KRAS and BRAF mutations increased along progression of MSS CRCs, suggesting that activation of both genes is likely to harbour a synergistic effect.

Colorectal Neoplasms↗
PubMed2006

The simple SDD.

We describe the fabrication and characterisation of the SIMPLE superheated droplet detector, a 10 g active mass device of C(2)ClF(5) in 1-3% weight concentrations currently employed in a direct search for spin-dependent astroparticle dark matter candidates.

Chlorofluorocarbons, Methane↗
PubMed2006

Genomic organization and evolution of the 5S ribosomal DNA in Tilapiini fishes.

5S rDNA sequences present an intense dynamism and have proved to be valuable as genetic markers to distinguish closed related species and also in the understanding of the evolutionary dynamic of repetitive sequences in the genomes. In order to identify patterns of 5S rDNA organization and their evolution in the genome of fish species, such genomic segment was investigated in the tilapias Oreochromis niloticus and Tilapia rendalli, and in the hybrid O. urolepis hornorum x O. mossambicus. A dual 5S rDNA system was identified in the three analyzed tilapia samples. Although each 5S rDNA class was conserved among the three samples, a distinct 5S rDNA genome organization pattern could be evidenced for each sample. The presence of a dual 5S rDNA system seems to be a general trait among non-related teleost fish orders, suggesting that evolutionary events of duplication have occurred before the divergence of the main groups of teleost fishes.

Animals↗
PubMed2006

Early determination of the reproductive number for vector-borne diseases: the case of dengue in Brazil.

OBJECTIVE: To evaluate a new method of deriving the reproductive number for vector-borne diseases from the early epidemic curves for vector-borne diseases with incubations in the vectors and in the hosts. METHOD: We applied the model to several dengue epidemics in different climatic regions of Brazil: Brasilia, Belém, Fortaleza, Boa Vista. RESULTS: The new method leads to higher estimates of the reproductive number than previous models. CONCLUSION: At present, Aedes aegypti densities, the meeting of more compatible strains of viruses and mosquitoes, may lead to re-emergence of urban yellow fever epidemics.

Aedes↗
PubMed2006

Genetic basis of Alzheimer's dementia: role of mtDNA mutations.

Alzheimer's disease (AD) is the most common neurodegenerative disorder associated to dementia in late adulthood. Amyloid precursor protein, presenilin 1 and presenilin 2 genes have been identified as causative genes for familial AD, whereas apolipoprotein E epsilon4 allele has been associated to the risk for late onset AD. However, mutations on these genes do not explain the majority of cases. Mitochondrial respiratory chain (MRC) impairment has been detected in brain, muscle, fibroblasts and platelets of Alzheimer's patients, indicating a possible involvement of mitochondrial DNA (mtDNA) in the aetiology of the disease. Several reports have identified mtDNA mutations in Alzheimer's patients, suggesting the existence of related causal factors probably of mtDNA origin, thus pointing to the involvement of mtDNA in the risk contributing to dementia, but there is no consensual opinion in finding the cause for impairment. However, mtDNA mutations might modify age of onset, contributing to the neurodegenerative process, probably due to an impairment of MRC and/or translation mechanisms.

Alzheimer Disease↗
PubMed2005

Cleft lip/palate and CDH1/E-cadherin mutations in families with hereditary diffuse gastric cancer.

We report the association of CDH1/E-cadherin mutations with cleft lip, with or without cleft palate (CLP), in two families with hereditary diffuse gastric cancer (HDGC). In each family, the CDH1 mutation was a splicing mutation generating aberrant transcripts with an in-frame deletion, removing the extracellular cadherin repeat domains involved in cell-cell adhesion. Such transcripts might encode mutant proteins with trans-dominant negative effects. We found that CDH1 is highly expressed at 4 and 5 weeks in the frontonasal prominence, and at 6 weeks in the lateral and medial nasal prominences of human embryos, and is therefore expressed during the critical stages of lip and palate development. These findings suggest that alteration of the E-cadherin pathway can contribute to human clefting.

Adult↗
PubMed2005

Spermatozoa ultrastructure in Sciaenidae and Polynemidae (Teleostei:Perciformes) with some consideration on Percoidei spermatozoa ultrastructure.

Spermatozoa ultrastructure was studied in five marines (Paralonchurus brasiliensis, Larimus breviceps, Cynoscion striatus, Micropogonias furnieri, Menticirrhus americanus, Umbrina coroides, Stellifer rastrifer), and one freshwater (Plagioscion squamosissimus) species of Sciaenidae and one species of Polynemidae (Polydactylus virginicus). The investigation revealed that, in all species, spermatozoa display a round head, a nucleus containing highly condensed, filamentous chromatin clusters, no acrosome, a short midpiece with a short cytoplasmic channel, and a flagellum showing the classic axoneme structure (9+2) and short irregular lateral fins. In Sciaenidae, the spermatozoa are type II, the flagellar axis is parallel to the nucleus, the lateral nuclear fossa is double arched, the centriolar complex is outside the nuclear fossa, the proximal centriole is anterior and perpendicular to the distal centriole, and no more than ten spherical (marine species) or elongate (freshwater species) mitochondria are observed. Polynemidae spermatozoa are of the intermediate type with the flagellar axis eccentric to the hemi-arc-shaped nucleus, and exhibit no nuclear fossa, the centriolar complex close to the upper nuclear end, the proximal centriole lateral and oblique to the distal centriole, and one large ring-shaped mitocondrion. The data available show that no characteristic is exclusively found in the spermatozoa of members of the Sciaenidae family when compared to other Percoidei with type II spermatozoa. However, three characteristics were exclusively found in Polynemidae: (1) the hemi-arched nucleus; the positioning of the centrioles; and (2) the ring-shaped mitocondrion. The interrelationships between Sciaenidae and Polynemidae as well as between these two families and other Percoidei are herein discussed.

Acrosome↗
PubMed2005

CA-125 AUC as a new prognostic factor for patients with ovarian cancer.

OBJECTIVE: The aim of the present study was to investigate the usefulness of the CA-125 area under the curve (AUC) as a new kinetic parameter for predicting overall survival in patients with ovarian cancer. In addition, the relationship of CA-125 AUC with other prognostic factors of ovarian cancer was evaluated. METHODS: Ninety-two patients that underwent primary line chemotherapy within 4 months after submission to cytoreductive surgery were included. For each patient, CA-125 AUC was calculated and a statistical analysis was conducted to compare CA-125 AUC behavior among patients according to several covariates. RESULTS: The mean age at diagnostic time was found to be 55.5 (16.1-82.4) years with a mean survival of 39.2 (3.5-100.1; SE = 2.6) months. Across FIGO stage I, II, III, and IV patients had a mean CA-125 AUC of 18.2, 24.6, 147.8, and 574.6 IU/ml*days, respectively (P < 0.05). At the evaluation date, living patients had a mean CA-125 AUC of 40.1 in contrast to 234.1 IU/ml*days (P < 0.05) for deceased ones. Patients with a complete response to primary chemotherapy had a mean CA-125 AUC of 48.8, while patients with a partial response had a mean of 251.7 IU/ml*days, and patients with no response or disease progression had a mean of 316.5 IU/ml*days (P < 0.05). The best CA-125 AUC performance is in predicting patient complete response to chemotherapy with a cut-off of 100 IU/ml*days and an accuracy of 82%. CONCLUSIONS: Despite CA-125 AUC high correlation with the FIGO stage, residual disease, and patient final outcome, the main interest of CA-125 AUC calculation is to evaluate the treatment efficacy and to foresee a full chemotherapy response. Further studies should be carried out before extrapolating these results to other data sets.

Adolescent↗
PubMed2005

Neutron spectrometry with large volume, heavy-loaded superheated droplet detectors: a simple spin-off.

SIMPLE is a superheated droplet detector (SDD) experiment designed to search for the evidence of spin-dependent weakly interacting neutralino dark matter (WIMPs). SDDs, a type of emulsion detector, consist of a uniform suspension of superheated liquid droplets in a compliant material such as a polymeric or aqueous gel. We report on the first neutron spectrometry experiments with SIMPLE SDDs, a spin-off of the neutron detector calibrations performed at the Portuguese Research Reactor. SIMPLE SDDs differ from most SDDs available commercially as they have a 10 times higher loading factor, containing 10(3) times more freon than their commercial counterparts and a 100 times larger volume. We have analysed the response of SIMPLE SDDs to two quasi-monochromatic neutron beams of energies 54 and 144 keV obtained with passive filters. Results show that the characteristic peaks in the fluence distribution of both filters could be determined and their energy position obtained using a simple thermodynamic relation.

Equipment Design↗
PubMed2005

Comparison of deterministic and Monte Carlo methods in shielding design.

In shielding calculation, deterministic methods have some advantages and also some disadvantages relative to other kind of codes, such as Monte Carlo. The main advantage is the short computer time needed to find solutions while the disadvantages are related to the often-used build-up factor that is extrapolated from high to low energies or with unknown geometrical conditions, which can lead to significant errors in shielding results. The aim of this work is to investigate how good are some deterministic methods to calculating low-energy shielding, using attenuation coefficients and build-up factor corrections. Commercial software MicroShield 5.05 has been used as the deterministic code while MCNP has been used as the Monte Carlo code. Point and cylindrical sources with slab shield have been defined allowing comparison between the capability of both Monte Carlo and deterministic methods in a day-by-day shielding calculation using sensitivity analysis of significant parameters, such as energy and geometrical conditions.

Algorithms↗
PubMed2005

Interim storage of spent and disused sealed sources: optimisation of external dose distribution in waste grids using the MCNPX code.

Radioactive sealed sources are in use worldwide in different fields of application. When no further use is foreseen for these sources, they become spent or disused sealed sources and are subject to a specific waste management scheme. Portugal does have a Radioactive Waste Interim Storage Facility where spent or disused sealed sources are conditioned in a cement matrix inside concrete drums and following the geometrical disposition of a grid. The gamma dose values around each grid depend on the drum's enclosed activity and radionuclides considered, as well as on the drums distribution in the various layers of the grid. This work proposes a method based on the Monte Carlo simulation using the MCNPX code to estimate the best drum arrangement through the optimisation of dose distribution in a grid. Measured dose rate values at 1 m distance from the surface of the chosen optimised grid were used to validate the corresponding computational grid model.

Computer Simulation↗
PubMed2005

Detection of axillary metastases in breast cancer patients using ultrasound and colour Doppler combined with fine needle aspiration cytology.

The aims of this study were to evaluate the diagnostic value of ultrasonography and colour Doppler combined with fine needle aspiration (FNA) cytology for the detection of non-palpable axillary lymph node metastases in breast cancer patients. Forty patients with operable breast cancer (T1/T2), invasive carcinoma, not submitted to neo-adjuvant therapy, underwent axillary ultrasonography and colour Doppler preoperatively. FNA cytology was performed on axillary lymph nodes presenting ultrasonographic and/or Doppler suspicious features. A total of 542 lymph nodes were surgically removed from the 40 patients; 19 were metastatic lymph nodes. Ultrasound-guided FNA detected metastases in six out of 11 histologically node-positive patients. Sensitivity and specificity in this preliminary study was 55% and 100%, respectively. These are the preliminary results of a prospective study that has the purpose of reducing the sentinel node procedures in breast cancer patients with clinically negative axillae, but positive FNA cytology.

Adult↗
PubMed2005

Differential expression of collagens type I and type IV in lymphangiogenesis during the angiogenic process associated with bleomycin-induced pulmonary fibrosis in rat.

In order to assess the role of collagens I and IV during the angiogenic process associated with bleomycin-induced pulmonary fibrosis in rat, in situ hybridization and immunocytochemical studies were carried out. An increased expression of collagen IV was observed before an enhanced expression of collagen I after intratracheal instillation of bleomycin. Deposits of both collagen types were detected on the 21st day after treatment with bleomycin, surrounding the new blood vessels formed during the fibrotic process. At this time, the presence of new lymphatic vessels was associated uniquely with deposition of collagen I. These observations lead us to conclude that, at least during pulmonary fibrosis, lymphangiogenesis takes place after blood angiogenesis.

Animals↗
PubMed2004

Chromosome evolution in the erythrinid fish, Erythrinus erythrinus (Teleostei: Characiformes).

The genus Erythrinus belongs to the family Erythrinidae, a neotropical fish group. This genus contains only two described species, Erythrinus erythrinus being the most widely distributed in South America. Six samples of this species from five distinct Brazilian localities and one from Argentina were studied cytogenetically. Four groups were identified on the basis of their chromosomal features. Group A comprises three samples, all with 2n = 54 chromosomes, a very similar karyotypic structure, and the absence of chromosome differentiation between males and females. One sample bears up to four supernumerary microchromosomes, which look like 'double minute chromosomes' in appearance. Groups B-D comprise the three remaining samples, all sharing an X(1)X(1)X(2)X(2)/X(1)X(2)Y sex chromosome system. Group B shows 2n = 54/53 chromosomes in females and males, respectively, and also shows up to three supernumerary microchromosomes. Groups C and D show 2n=52/51 chromosomes in females and males, respectively, but differ in the number of metacentric, subtelocentric, and acrocentric chromosomes. In these three groups (B-D), the Y is a metacentric chromosome clearly identified as the largest in the complement. The present results offer clear evidence that local samples of E. erythrinus retain exclusive and fixed chromosomal features, indicating that this species may represent a species complex.

Animals↗