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Biomedical subjects

A Sousa

Publications and source records attributed to A Sousa.

At least 19 recordsLinked to original sources
PubMed2005

Population genetics of wild-type CAG repeats in the Machado-Joseph disease gene in Portugal.

OBJECTIVE: To gain insights on the molecular mechanisms of mutation that led to the emergence of expanded alleles in the MJD gene, by studying the behavior of wild-type alleles and testing the association of its distribution with the representation of the disease. METHODS: The number of CAG motifs in the MJD gene was determined in a representative sample of 1000 unrelated individuals. Associations between the repeat size and the epidemiological representation of MJD were tested. RESULTS: The allelic profile of the total sample was in the normal range (13-41 repeats), with mode (CAG)23. No intermediate alleles were present. Allelic size distribution showed a negative skew. The correlation between the epidemiological representation of MJD in each district and the frequency of small, medium and large normal alleles was not significant. Further correlations performed grouping the districts also failed to produce significant results. CONCLUSIONS: The absence of association between the size of the repeats and the representation of MJD demonstrates that prevalence is not an indirect reflection of the frequency of large normal alleles. Globally the results obtained are in accordance with a model that postulates the occurrence of a few mutations on the basis of most of the MJD cases worldwide.

Ataxin-3↗
PubMed2005

ONTOFUSION: ontology-based integration of genomic and clinical databases.

ONTOFUSION is an ontology-based system designed for biomedical database integration. It is based on two processes: mapping and unification. Mapping is a semi-automated process that uses ontologies to link a database schema with a conceptual framework-named virtual schema. There are three methodologies for creating virtual schemas, according to the origin of the domain ontology used: (1) top-down--e.g. using an existing ontology, such as the UMLS or Gene Ontology--, (2) bottom-up--building a new domain ontology-- and (3) a hybrid combination. Unification is an automated process for integrating ontologies and hence the database to which they are linked. Using these methods, we employed ONTOFUSION to integrate a large number of public genomic and clinical databases, as well as biomedical ontologies.

Data Collection↗
PubMed2004

Synergy between medical informatics and bioinformatics: facilitating genomic medicine for future health care.

In this paper, we review the results of BIOINFOMED, a study funded by the European Commission (EC) with the purpose to analyse the different issues and challenges in the area where Medical Informatics and Bioinformatics meet. Traditionally, Medical Informatics has been focused on the intersection between computer science and clinical medicine, whereas Bioinformatics have been predominantly centered on the intersection between computer science and biological research. Although researchers from both areas have occasionally collaborated, their training, objectives and interests have been quite different. The results of the Human Genome and related projects have attracted the interest of many professionals, and introduced new challenges that will transform biomedical research and health care. A characteristic of the 'post genomic' era will be to correlate essential genotypic information with expressed phenotypic information. In this context, Biomedical Informatics (BMI) has emerged to describe the technology that brings both disciplines (BI and MI) together to support genomic medicine. In recognition of the dynamic nature of BMI, institutions such as the EC have launched several initiatives in support of a research agenda, including the BIOINFOMED study.

Biotechnology↗
PubMed2002

Oxidative stress in toadfish (Halobactrachus didactylus) cardiac muscle. Acute exposure to vanadate oligomers.

Vanadate solutions as "metavanadate" (containing ortho and metavanadate species) and "decavanadate" (containing mainly decameric species) (5 mM; 1 mg/kg) were injected intraperitoneously in Halobatrachus didactylus (toadfish), in order to evaluate the contribution of decameric vanadate species to vanadium (V) intoxication on the cardiac tissue. Following short-term exposure (1 and 7 days), different changes on antioxidant enzyme activities-superoxide dismutase (SOD), catalase (CAT), selenium-glutathione peroxidase (Se-GPx), total glutathione peroxidase (GPx), lipid peroxidation and subcellular vanadium distribution were observed in mitochondrial and cytosolic fractions of heart ventricle toadfish. After 1 day of vanadium intoxication, SOD, CAT and Se-GPx activities were decreased up to 25%, by both vanadate solutions, except mitochondrial CAT activity that increased (+23%) upon decavanadate administration. After 7 days of exposure, decavanadate versus metavanadate solutions promoted different effects mainly on cytosolic CAT activity (-56% versus -5%), mitochondrial CAT activity (-10% versus +10%) and total GPx activity (+1% versus -35%), whereas lipid peroxidation products were significantly increased (+82%) upon 500 microM decavanadate intoxication. Accumulation of vanadium in total (0.137+/-0.011 microg/g) and mitochondrial (0.022+/-0.001 microg/g) fractions was observed upon 7 days of metavanadate exposure, whereas for decavanadate, the concentration of vanadium increased in cytosolic (0.020+/-0.005 microg/g) and mitochondrial (0.021+/-0.009 microg/g) fractions. It is concluded that decameric vanadate species are responsible for a strong increase on lipid peroxidation and a decrease in cytosolic catalase activity thus contributing to oxidative stress responses upon vanadate intoxication, in the toadfish heart.

Animals↗
PubMed2002

The influence of core materials and film coating on the drug release from coated pellets.

The objective of this study was to analyse the influence of the composition of the core of the pellets on the in vitro drug release profile. The different materials (drugs and fillers) were chosen according to their relative solubility. Pellets were prepared by a standardised process of extrusion/spheronisation. A selected fraction size (1-1.4 mm diameter) of pellets of each preparation was coated with Surelease (an aqueous dispersion of ethyl cellulose) to give 5% weight gain. The dissolution studies were performed and data analysed in terms of the Area under the Curve (AUC) of the % dissolved as function of time and Mean Dissolution Time (MDT). ANOVA was applied in order to identify the influence factors and the relationship of cross effects. Canonical analysis and multiple regression were employed to quantify these relationships. The film coat was found to be the major factor controlling the drug release. The results however, show that both drug and filler solubility influenced the drug release profile. Some of the unusual results could only be explained if consideration was given to the physical characteristics of both powder and pellets. In particular, the specific surface area of calcium phosphate compared with other fillers played an important role on the release profile of the model drug.

Cellulose↗
PubMed2002

Factors influencing the physical characteristics of pellets obtained by extrusion-spheronization.

The objective of this work was to analyse the influence of the solubility of the drug and the filler on the physical characteristics of pellets prepared by extrusion/spheronization. Different formulations were prepared according to a statistical plan, using five different drugs and five different fillers selected according to their water solubility. The pellets were then obtained by a standardized extrusion/spheronization process and evaluated in terms of their physical characteristics by measuring the pellet size, density, porosity, mechanical strength, residual moisture after drying and shape. The results were first analysed by the analysis of variance to identify the main factors involved. The results were further assessed by canonical analysis and the significant influence factors were quantified in terms of regression equations. It can be concluded that the solubility of materials used (both drugs and fillers) plays an important role in the quantity of water required to form satisfactory pellets and on the physical characteristics of pellets. Quantitative relationships were identified between (a) the extrusion force required to provide extrudate, which would form pellets and the natural log of the filler solubility; (b) the quantity of the pellets in the size range 1-1.4 and the solubility of both the filler and the drug; (c) the apparent pellet density and both the level of drug and filler plus the solubility of the filler; (d) the pellet porosity and the quantity of drug and the inverse function of the filler solubility; and (e) the mechanical strength of the pellets and the square root of the quantity of drug.

Analysis of Variance↗
PubMed2001

Results of surgery in patients with refractory extratemporal epilepsy with normal or nonlocalizing magnetic resonance findings investigated with subdural grids.

PURPOSE: To study the efficacy of extensive coverage of the brain surface with subdural grids in defining extratemporal cortical areas amenable for resection in patients with refractory extratemporal epilepy (R-ExTE) and normal or nonlocalizing magnetic resonance imaging (MRI) scans. METHODS: Sixteen patients with R-ExTE were studied. Eleven patients had simple partial, eight had complex partial, and three had supplementary motor area seizures. Seizure frequency ranged from three per month to daily episodes. Interictal EEG showed large focal spiking areas in 11 patients, secondary bilateral synchrony in four, and was normal in one patient. Surface ictal recordings were nonlocalizing in six patients, and in 10, they disclosed large ictal focal spiking areas. MRI was normal in 10 patients, and in six patients, focal nonlocalizing potentially epileptogenic lesions were found. All patients were given an extensive coverage of the cortical convexity with subdural electrodes through large unilateral (n = 13) or bilateral (n = 3) craniotomies. Bipolar cortical stimulation was carried out through the implanted electrodes. RESULTS: Interictal invasive recording findings showed widespread spiking areas in 13 patients and secondary bilateral synchrony in three. Ictal invasive recordings showed focal seizure onset in all patients. There were six frontal, two parietal, one temporooccipital, four rolandic, and three posterior quadrant resections. Thirteen patients had been rendered seizure free after surgery, and three had > or =90% of seizure-frequency reduction. Pathologic findings included gliosis (n = 10), cortical dysplasia (n = 5), or no abnormalities (n = 1). Six patients had transient postoperative neurologic morbidity. CONCLUSIONS: Extensive subdural electrodes coverage seems to be an effective way to investigate patients with R-ExTE and normal or nonlocalizing MRI findings.

Adolescent↗
PubMed2001

Seizure's outcome after cortical resections including the face and tongue rolandic areas in patients with refractory epilepsy and normal MRI submitted to subdural grids' implantation.

PURPOSE: To study the seizure's outcome in patients with refractory epilepsy and normal MRI submitted to resections including the rolandic cortex. METHODS: Four adult patients were studied. All patients had motor or somatosensory simple partial seizures and normal MRI and were submitted to subdural grids' implantation with extensive coverage of the cortical convexity (1 in the non-dominant and 3 in the dominant hemisphere). RESULTS: ECoG was able to define focal areas of seizures' onset in every patient. All patients were submitted to resection of the face and tongue motor and sensitive cortex; two patients had resections including the perirolandic cortex and 2 had additional cortical removals. Three patients are seizures' free and one had a greater then 90% reduction in seizure frequency. CONCLUSION: Resections including the face and tongue rolandic cortex can be safely performed even within the dominant hemisphere.

Adult↗
PubMed2001

Physical excercise and thrombotic risk in the elderly.

UNLABELLED: Aging increases certain thrombotic risk factors, such as fibrinogen, factor VII, PAI-1 and plasma viscosity, contributing to cardiovascular diseases being the principal cause of death in developed countries. Physical exercise can counteract this tendency by influencing such factors. PURPOSE: To assess the effect of regular physical exercise on fibrinogen, factor VII, PAI-1 and plasma viscosity in an elderly group. METHODS: Sixty-three old people of both sexes, aged between 65 and 94, participated in this study, and were randomly distributed between a test group (n = 31) and a control group (n = 32). The test group followed a program of physical exercise for eight months, with an intensity of 60% to 80% of heart rate reserve, composed of three weekly sessions, on alternate days, of 60 minutes each. The control group maintained their normal activity. Before the beginning of the program and eight months afterwards, blood samples were collected to assess fibrinogen, factor VII, PAI-1 and plasma viscosity. RESULTS: In the test group, fibrinogen, factor VII and plasma viscosity decreased significantly while PAI-1 showed no significant change. The control group did not present alterations in any of the parameters assessed. CONCLUSIONS: Regular physical exercise decreases thrombotic risk and may help to reduce cardiovascular events in the elderly.

Age Factors↗
PubMed2000

Hexaaquacobalt(II) bis(4-toluenesulfonate).

The title compound, [Co(H(2)O)(6)](CH(3)C(6)H(4)SO(3))(2), has a structure where the metal atom is surrounded by six molecules of water forming the cation and the anion is deprotonated 4-toluenesulfonic acid. The Co atom is in a nearly regular octahedral coordination geometry, with Co-O distances between 2.0529 (14) and 2.0810 (16) A, and angles ranging from 87.25 (9) to 92.75 (9) degrees. The supramolecular structure consists of parallel layers of cations and anions. The anions are arranged with their sulfonate groups directed towards the cation layer in an alternating fashion and form hydrogen bonds with the water molecules of the cation.

Journal Article↗
PubMed2000

Bis[2-(diphenylphosphinoyl)benzene] disulfide.

The title compound, [2-Ph(2)P(O)C(6)H(4)S](2) or C(36)H(28)O(2)P(2)S(2), obtained by electrochemical oxidation of 2-(diphenylphosphino)benzenethiol, has twofold crystallographic symmetry. Principal dimensions include S-S 2.0212 (15) A, S-C 1.786 (3) A and C-S-S-C 81.34 (14) degrees.

Journal Article↗
PubMed2000

Paradigms for subdural grids' implantation in patients with refractory epilepsy.

RATIONALE: The need for invasive monitoring in patients with refractory epilepsy has been greatly reduced by the introduction of new technologies such as PET, SPECT and MRI in the clinical practice. On the other hand, 10 to 30% of the patients with refractory epilepsy have non-localizatory non-invasive preoperative work-up results. This paper reports on the paradigms for subdural electrodes implantation in patients with different refractory epileptic syndromes. METHODS: Twenty-nine adult refractory epileptic patients were studied. Patients were divided into five different epileptic syndromes that represented the majority of the patients who needed invasive recordings: bitemporal (Group I; n=16 ), bi-frontal-mesial (Group II, n=5), hemispheric (Group III; n=2), anterior quadrant (Group IV; n=3) and posterior quadrant (Group V; n=3). All of them were submitted to extensive subdural electrodes' implantation (from 64 to 160 contacts) covering all the cortical surface potentially involved in epileptogenesis under general anesthesia. RESULTS: All patients tolerated well the procedure. There was no sign or symptom of intracranial hypertension except for headache in 22 patients. In all except one Group II patient, prolonged electrocorticographic monitoring using the described subdural cortical coverage patterns was able to define a focal area amenable for resection. In all Groups II-V patients cortical stimulation was able to adequately map the rolandic and speach areas as necessary. CONCLUSION: Despite recent technological advances invasive neurophysiological studies are still necessary in some patients with refractory epilepsy. The standardization of the paradigms for subdural implantation coupled to the study of homogeneous patients' populations as defined by MRI will certainly lead to a better understanding of the pathophysiology involved in such cases and an improved surgical outcome.

Adult↗
PubMed2000

Results of surgery in patients with bilateral independent temporal lobe spiking (BITLS) with normal MRI or bilateral mesial temporal sclerosis (MTS) investigated with bilateral subdural grids.

PURPOSE: The introduction of new technologies in the clinical practice have greatly decreased the number of patients submitted to invasive recordings. On the other hand, some patients with refractory temporal lobe epilepsy have normal MR scans or bilateral potentially epileptogenic lesions. This paper reports the results of invasive neurophysiology and surgical outcome in such patients. METHOD: Sixteen patients were studied. Eleven had normal MRI (Group I) and five had bilateral mesial temporal sclerosis (Group II). All patients had BITLS and non-localizatory seizures on video-EEG monitoring. All patients were implanted bilaterally with 32-contacts subdural grids. They were submitted to a cortico-amygdalo-total hippocampectomy at the side defined by chronic electrocorticography (ECoG). RESULTS: In Group I, seizures came from a single side in nine patients. In nine patients, seizures started at one side, spread to the ipsolateral contacts and contralaterally afterwards. On the other hand, in two Group I patients seizures started in one mesial region and spread to the contralateral parahippocampus and neocortex before spreading to ipsolateral contacts. All patients in Group II had seizures starting unilaterally with focal EcoG onset in the mesial regions. Eight Group I patients are seizure-free and three are in Engel's class II. Eighty percent of Group II patients are seizure-free after surgery and one patient is in Engel's class II. CONCLUSION: Good surgical results can be obtained in patients with BITLS. Patients with normal MRI seem to have a worse prognosis when compared to patients with unilateral or even bilateral MTS. Extensive subdural coverage is essential in patients with normal MRI.

Adult↗
PubMed2000

Laparoscopic assessment and orchidectomy for the adult undescended testis.

The aim of this study was assessment of the usefulness of laparoscopy in the diagnosis and treatment of the adult nonpalpable testicle. We reviewed retrospectively the case notes of five adult patients with cases of impalpable testis that were evaluated and treated laparoscopically in our institutions. All five patients had unilateral nonpalpable testicles. The mean age of the patients was 36.5 years (+/- 5 years). Laparoscopy defined the intraabdominal anatomy accurately in all cases, and there were no laparoscopic complications. Two testes were found intra-abdominally, another testicle was found lying in the inguinal canal, and the last two testes were absent. Laparoscopy is a safe and reliable method in diagnosing adults with nonpalpable testis and also allows the completion of the operative procedure during a 1-day hospital stay.

Adult↗