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Biomedical subjects

B Nunes

Publications and source records attributed to B Nunes.

14 recordsLinked to original sources
PubMed2005

Acute insulin response of donors is correlated with pancreatic islet isolation outcome in the pig.

AIMS/HYPOTHESIS: Unpredictability of islet isolation outcome remains a frustrating and costly issue in the clinical implementation of islet transplantation. The aim of this experimental study was to test the hypothesis that the donor's insulin secretory reserve, an in vivo surrogate of functional pancreatic mass, is correlated with the outcome of islet isolation. METHODS: Insulin secretory reserve was evaluated in 28 healthy adult minipigs prior to pancreatectomy and islet isolation. Blood glucose and insulinaemia were measured before and 1, 3, 5, 10, 15, 30, 60 and 90 min after glucose infusion. Following total pancreatectomy, islet isolation was performed according to Ricordi's semi-automated method, and the total number of islets obtained was determined. Fasting blood glucose, insulinaemia, acute insulin response (AIR), maximal insulinaemia and the glucose decay constant (K(G)) were calculated, and possible associations with the outcome of islet isolation were assessed. RESULTS: AIR and maximal insulinaemia after glucose injection were correlated with the outcome of islet isolation (p<0.01). Mean values for AIR and maximal insulinaemia were significantly different between animals in which islet isolation was successful (n=11) vs those in which it was unsuccessful (n=17) (77.6+/-13.7 microU/ml vs 42.3+/-7.8 microU/ml, p<0.05; 144.7+/-21.6 microU/ml vs 71.9+/-10.4 microU/ml, p<0.05, respectively). CONCLUSIONS/INTERPRETATION: This study suggests that the donor's pancreatic endocrine mass, as estimated by AIR, is a major determinant of the outcome of islet isolation in large mammals. Our results may explain the frustrating variability of human islet isolation outcome and could lead to a new approach for optimising the selection of brain-dead and/or living pancreas donors.

Animals↗
PubMed2005

Effects of widely used pharmaceuticals and a detergent on oxidative stress biomarkers of the crustacean Artemia parthenogenetica.

Pharmaceuticals are continuously dispersed into the environment as a result of human and veterinary use, posing relevant environmental concerns. The present paper reports the acute toxic effects of three therapeutic agents (diazepam, clofibrate and clofibric acid) and a detergent, sodium dodecylsulphate (SDS), to the hypersaline crustacean Artemia parthenogenetica. This study specially focused on oxidative stress parameters, namely (1) total and selenium-dependent glutathione-peroxidase (GPx), (2) glutathione reductase (GRed), (3) total superoxide dismutase (SOD), and (4) glutathione-S-transferases (GSTs). The effects of tested substances on lipid peroxidation (thiobarbituric acid reactive substances, TBARS), and soluble cholinesterases (ChE) were also investigated. Diazepam caused a significant inhibition of ChE (LOEC = 7.04 mg/l) and total GPx activities. SDS was responsible for a decrease in the activity of both ChE (LOEC = 8.46 mg/l) and GRed (LOEC = 4.08 mg/l). Both fibrates (clofibrate and clofibric acid) were responsible for significant decreases in Se-dependent GPx, with LOEC values of 176.34 and 3.09 mg/l, respectively. Clofibrate also caused a slight increase of TBARS content of A. parthenogenetica homogenates. These results indicate that the exposure to all the tested compounds induced alterations on the cellular redox status in A. parthenogenetica. In addition, diazepam was shown to have the capability of interfering with A. parthenogenetica neurotransmission, through the inhibition of ChE.

Animals↗
PubMed2005

[Technique of pancreatic procurement for pancreatic islet isolation].

AIM OF THE STUDY: The allograft of pancreatic islets represents a potential alternative to insulin therapy in patients suffering from the most severe forms of Type 1 diabetes. Here we report our experience of pancreatic procurement for isolation and islet allograft. MATERIALS AND METHODS: Pancreata were procured in brain-dead donors. The islets were isolated using techniques developed and validated in pigs and men. Injection of a given preparation was decided after quantitative and qualitative controls. Islets were transplanted in Type 1 diabetic patients already grafted with a kidney or suffering from severe and/or unstable diabetes, after percutaneous or surgical settlement of an intra-portal catheter. Patients received an "Edmonton-like" immunosuppressive protocol. Grafts were repeated once or twice until a total quantity of 10,000 transplanted islet-equivalents was obtained. RESULTS: Twenty-nine pancreata were procured and 14 preparations were grafted to 7 patients. Eleven graftings were done percutaneously and three were surgical. The initial function of the 14 transplants was confirmed by secretion of C-peptide and decrease of insulin doses. Insulin therapy was completely interrupted in the 5 patients having received at least two grafts. CONCLUSION: These preliminary clinical results confirmed that the isolation technique of human islets and the technique of pancreas procurement are mastered by our team. If the results of this assay (assessment one year after graft) confirm our hopes, we will be able to offer islet allografts to an increasing number of patients with severe Type 1 diabetes.

Animals↗
PubMed2005

Acute toxicity of widely used pharmaceuticals in aquatic species: Gambusia holbrooki, Artemia parthenogenetica and Tetraselmis chuii.

Pharmaceuticals are continuously dispersed into the environment as a result of human and veterinary use, posing relevant environmental concerns. This study evaluated the acute toxicity of three therapeutic agents (diazepam, clofibrate, and clofibric acid) and a detergent (sodium dodecyl sulfate; SDS) in three aquatic species, namely the euryhaline fish Gambusia holbrooki, the hypersaline crustacean Artemia parthenogenetica, and the marine algae Tetraselmis chuii. The ranking of 50% lethal concentrations (LC50) for the two animal species and 50% inhibitory concentration (IC50) for the algal species was, in decreasing order, clofibric acid > SDS > diazepam > clofibrate for G. holbrooki, clofibric acid > clofibrate > SDS > diazepam for A. parthenogenetica, and clofibric acid > clofibrate > SDS > diazepam for T. chuii. These differences show that the intrinsic nature of test organisms must be considered when evaluating the toxicity of these agents to aquatic ecosystems.

Animals↗
PubMed2005

Characterization and use of the total head soluble cholinesterases from mosquitofish (Gambusia holbrooki) for screening of anticholinesterase activity.

Inhibition of cholinesterases (ChE) has been widely used as an environmental biomarker of exposure to organophosphates (OP) and carbamate (CB) pesticides. Different ChE isoforms may be present in the same tissue and may present distinct sensitivities towards environmental contaminants. The present work characterises the soluble ChE present in mosquitofish (Gambusia holbrooki) total head homogenates, through the use of different substrates and selective inhibitors of cholinesterasic activity. Furthermore, the effects of sodium dodecylsulphate (SDS) on the enzymatic activity were investigated, both in vivo and in vitro. These results showed that acetylcholinesterase (AChE) seemed to be the predominant form present in head homogenates of G. holbrooki, despite the inhibition by tetraisopropylpyrophosphoramide (iso-OMPA) found at high concentrations. SDS was responsible for in vitro, but not in vivo, inhibitory effects. The in vitro AChE inhibitory effects of SDS was partially prevented by the use of increasing amounts of ethanol, suggesting that the inhibition was induced by an emulsion effect, which may explain the lack of effect in vivo.

Animals↗
PubMed2004

Acute and chronic effects of clofibrate and clofibric acid on the enzymes acetylcholinesterase, lactate dehydrogenase and catalase of the mosquitofish, Gambusia holbrooki.

The objective of this study was to investigate both acute and chronic effects of clofibrate and clofibric acid on the enzymes acetylcholinesterase (AChE), lactate dehydrogenase (LDH) and catalase (CAT) of the mosquitofish (Gambusia holbrooki). AChE, commonly used as a biomarker of neurotoxicity, was determined in the total head. LDH, an important enzyme of anaerobic metabolism, was quantified in dorsal muscle, and CAT, enzyme which has been used as indicative parameter of peroxisome proliferation, was determined in the liver. Furthermore, alterations of body and liver weight were also determined, through the calculation of the ratios final body weight/initial body weight, liver weight/final body weight, liver weight/gills weight and liver weight/head weight. Acute exposure of G. holbrooki to both clofibrate and clofibric acid induced a decrease in liver CAT activity, an increase in muscle LDH activity, while no effects were observed on AChE activity. However, chronic exposure did not alter significantly the enzymatic activities, suggesting reduced or null effects over these pathways, relative to effects reported in other species. No effects were observed for the calculated ratios, except a significant weight reduction for males chronically exposed to clofibrate.

Acetylcholinesterase↗
PubMed2001

Dealing with emergencies in rural areas of Europe: proceedings from WONCA Europe 2000.

On 4 July 2000, two workshops on handling emergencies in rural areas of Europe were held at the WONCA (World Organisation of National Colleges and Academies of Family Medicine/General Practice) conference in Vienna under the auspices of EURIPA (European Rural and Isolated Practitioners' Association). Papers submitted covered varying patterns of service provision and examples of short intensive training for emergencies at resident and general practitioner levels. Ways of collecting data routinely for accident prevention were also discussed. The workshops concluded that there was a need for more research in the application of emergency skills, that lack of confidence in dealing with emergencies may contribute to recruitment problems, and that further work towards a document detailing training requirements for emergencies was needed. This will be developed at a EURIPA workshop at WONCA in Tampere, June 2001.

Accident Prevention↗
PubMed1998

[Prospective registry of cerebrovascular diseases. Characterization of patients and methodology evaluation].

UNLABELLED: Hospital-based stroke data banks can contribute to a better management of stroke patients with consequent reduction of associated morbidity and mortality. OBJECTIVE: The characterisation of stroke patients and validation of the hospital stroke registry. SETTING: Hospital S.Pedro, Vila Real, a secondary neurological referral centre for 450.000 inhabitants of interior north Portugal. PATIENTS AND METHODS: Analysis of data collected over one year of a prospective computerised stroke registry. Evaluation of completeness of the registry by independent analysis from emergency room data files and percentage of items entirely filled up. RESULTS: in a one year period were registered 349 patients (186 F; 163 M) with a mean age at stroke of 69 years. The majority (73.3%) lived in the hospital district. Most patients went directly to the hospital from their homes, and in the first 24 hours of symptoms onset. Cerebral infarction was diagnosed in 35.2% of patients, followed from lacunas in 24.6% and hypertensive haemorrhages in 22.3%. Arterial hypertension was found in 60.1% of cases, there were 11.4% of deaths and a Rankin score > 3 was present at hospital discharge in 39.5% of patients. There was a decrease in the register during the one-year period, evaluated comparing two months of emergency room files; we found a missing rate of protocols items varying from 0.8% and 8.8%. CONCLUSIONS: Hospital-based stroke data banks can provide the best available information on stroke patients characteristics and the presence of stroke risk factors. Registry protocols must be kept simple, easy to fill and periodically surveyed in order to lessen the number of missing items.

Adult↗
PubMed1997

[Prognostic factors in intraparenchymatous cerebral hemorrhages. An analysis of a hospitalization series].

We studied 76 patients, with the diagnosis of spontaneous intracerebral haematoma confirmed by CT scan, admitted to the Internal Medicine Department of S. Pedro Hospital, Vila Real, from 1991 to 93. Neurologic examination, radiological characteristics, previous diseases, clinical evolution and treatment were analysed to select prognostic factors in relation to length of stay, functional status and mortality. Length of stay varied between 1 and 63 days and it is estimated that 50% of these patients have a length of stay of less than 22 days. In what concerns length of stay, the localisation of haematoma (p < 0.001) and presence/absence of systemic infections (p < 0.001) were the most significant prognostic factors. The haematomas localised in the brain stem or cerebral deep massive and the occurrence of systemic complications were associated to a longer hospital stay. None of the parameters analysed were related to functional status (Rankin scale), despite the fact that functional impairment was present in 57.1% of the patients whose hemorrhage had ventricular blood, compared with 27.5% whose hemorrhage had no ventricular blood. In this series, the mortality rate was 29.2% and the presence/absence of ventricular blood was the most important prognostic factor (p < 0.001). The mortality rate in patients whose haematoma presented ventricular blood was five times higher than in the remainder.

Aged↗
PubMed1995

Spectrum of epilepsy in neurocysticercosis: a long-term follow-up of 143 patients.

To characterize the clinical profile and the prognostic factors of the epilepsy due to parenchymal neurocysticercosis (NCC) 143 patients were analysed. Patients (62 men, 81 women) had a mean age at epilepsy onset of 29 years (range 2-71), mean epilepsy duration of 16 years (range 1-58) and mean follow-up of 5.2 years. Seizures were generalised tonic-clonic (GTC) in 50 patients (35%), simple partial (SP) in 66 (46%) and complex partial (CP) in 27 (19%). Epilepsy began as a single seizure in 73% and as a cluster of seizures or status epilepticus in 27%. Seizures were controlled in 64% of patients. Multivariate analysis revealed that significant prognostic factors associated with seizure control were type of seizures and age at epilepsy onset. Control is more likely in GTC and SP seizures and in patients with a higher age at seizures onset. Our analysis establishes that epilepsy due to NCC is a heterogeneous syndrome concerning age and mode of onset, seizure type, duration of epilepsy and pattern of evolution probably related with different pathogenic mechanisms.

Adolescent↗
PubMed1992

Posttraumatic epilepsy in civilians: clinical and electroencephalographic studies.

Posttraumatic epilepsy (PTE) is a known consequence of head trauma. The factors involved in posttraumatic seizures generation and the relationship between acute seizures and posttraumatic epilepsy are not without controversy. This also applies to the evolution of the electroencephalographic characteristics. The study here reported was performed analysing data from patients with posttraumatic epilepsy (N = 205) and data from patients followed-up since trauma and considered as a high risk population for the development of PTE (patients with acute seizures and/or patients with focal lesions--contusion, haematomas or penetrating head injury) (N = 152). Seizure type was associated with age and trauma severity (children, elderly and worst trauma cases present with a higher proportion of partial seizures). Neurological deficit and lesion location were associated with the seizure occurrence. The increased incidence of seizures was found when the most diffused brain dysfunction was combined with neurological deficits. The analysis of sequential EEGs performed at first, at 6th and 12 months post trauma revealed a non-stationary pattern throughout these time periods with EEG focal abnormalities remaining frequent for more than two years after the trauma. Children and old people have a higher proportion of EEG abnormalities with more frequent abnormal generalized activity in children and more frequent abnormal focal EEG activity in the elderly.

Adult↗
PubMed1992

Mental deterioration at epilepsy onset: a hypothesis.

In this study, we hypothesized a type of mental deterioration in epilepsy, characterized as a discontinued, cascading process, i.e. a sudden mental decline in a limited time interval, immediately after the onset of the seizures. The posttraumatic epilepsy model (PTE) may appear to be exceptionally useful in avoiding one of the major methodological obstacles for testing this hypothesis, i.e. the unavailability of test results obtained with the same battery of tests prior to and directly after the onset of the seizures. We propose a multicentre study in which a large group of patients are assessed, after recovering from the direct aftermath of head injury, but before the onset of PTE. This baseline provides an opportunity for longitudinal follow-up. Full recovery from head injury before the onset of PTE is to be expected in the mild and moderate groups of closed head injury patients. In this category, approximately 2000 head injured patients have to be assessed to obtain a reasonable group of approximately 100-200 PTE patients. This group will be followed during the critical period of 2-3 years after the onset of epilepsy.

Adolescent↗