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Biomedical subjects

A Pena

Publications and source records attributed to A Pena.

At least 19 recordsLinked to original sources
PubMed2006

Estimation of ochratoxin A in portuguese population: new data on the occurrence in human urine by high performance liquid chromatography with fluorescence detection.

With increasing knowledge of the persistence of OTA in the food chain, exposure to this mycotoxin is a potential human health hazard to humans, and evaluating its presence in populations has become highly important. A sensitive and accurate analytical method for the determination of ochratoxin A in urine was validated, since is less invasive than blood monitoring. It involves extraction with 5% NaHCO3, immunoaffinity column (IAC) for clean-up and high performance liquid chromatography with fluorescence detection (HPLC-FD). The limit of quantification was 0.02 ng/mL of urine (1.3 ng/mL of the extract injected) and recovery of ochratoxin A from urine samples spiked at the three fortification levels, were higher than 90% with RSD lower than 9%. The identification of OTA was confirmed by methyl ester derivatization and then HPLC analysis. Based in ours first results we can assume that OTA conjugation with glucuronic acid in human urine occurs. In the present study, we follow up OTA levels in 60 urine samples of inhabitants from Coimbra city, Portugal, in order to evaluate population contamination, and the presence of OTA was found in 42 samples, at concentrations above the LOQ, ranged between 0.021 and 0.105 ng/mL.

Adult↗
PubMed2005

Diffusion tensor imaging in chronic head injury survivors: correlations with learning and memory indices.

Diffusion tensor imaging (DTI) provides a unique insight into the cellular integrity of the brain. While conventional magnetic resonance imaging underestimates the extent of pathology following closed head injury, diffusion-weighted imaging has been shown to more accurately delineate the extent of cerebral damage. There have only been a few case studies of DTI in chronic head injury survivors. This study used DTI to investigate changes in anisotropy and diffusivity in survivors of head injury at least 6 months after their injury. The relationship between cognition and diffusion abnormality was also investigated. The voxel-based analysis revealed significant bilateral decreases in anisotropy, in major white matter tracts and association fibers in the temporal, frontal, parietal and occipital lobes. Statistically significant increases in diffusivity were also found in widespread areas of the cortex. A significant positive correlation was found between diffusivity and impairment of learning and memory in the left posterior cingulate, left hippocampal formation and left temporal, frontal and occipital cortex. The common pattern of abnormality despite heterogeneous injury mechanism and lesion location in the group suggests that these cellular changes reflect secondary insults. The importance of diffusion abnormalities in head injury outcome is emphasized by the significant correlation between a learning and memory index and diffusivity in areas known to subserve this cognitive function.

Adolescent↗
PubMed2005

Determination of ochratoxin A in Portuguese rice samples by high performance liquid chromatography with fluorescence detection.

A sensitive and accurate analytical method for the determination of ochratoxin A (OTA) in rice, based on extraction with phosphate-buffered saline/methanol, an immunoaffinity column (IAC) for clean-up, and high performance liquid chromatography with fluorescence detection (HPLC-FD), is described. The limit of quantification of the proposed method was 0.05 microg kg(-1). Recovery of OTA from rice samples spiked at 0.05 microg kg(-1) was 92%, with a within-day RSD of 5.4%. The proposed method was applied to 42 rice samples from Portugal and the presence of OTA was found in six samples at concentrations ranging from 0.09 to 3.52 microg kg(-1). The identification of OTA was confirmed by methyl ester derivatization and then HPLC analysis. The daily intake of OTA by the Portuguese population was also estimated.

Chromatography, High Pressure Liquid↗
PubMed2005

Validation of an analytical methodology for determination of oxytetracycline and tetracycline residues in honey by HPLC with fluorescence detection.

An analytical method for the determination of OTC and TC residues in honey was developed. Sample treatment involves an extraction in EDTA-McIlvaine buffer, followed by a solid-phase cleanup step. With regard to the cleanup procedure, different SPE cartridges were evaluated and the results presented. The method was validated according to the guidelines laid down by the 2002/657/EC European Decision parameters: decision limit (Cc alpha) and detection capability (CC beta) were 20 and 21 microg/Kg and 49 and 50 microg/Kg for OTC and TC, respectively, and recoveries of OTC and TC from spiked samples, at three fortification levels, were higher than 87% for both compounds. The analytical method was applied to 57 honey samples.

Chromatography, High Pressure Liquid↗
PubMed2005

Imaging of cerebral blood flow and metabolism in brain injury in the ICU.

The heterogeneity of the initial insult and subsequent pathophysiology has made both the study of human head injury and design of randomised controlled trials exceptionally difficult. The combination of multimodality bedside monitoring and functional brain imaging positron emission tomography (PET) and magnetic resonance (MR), incorporated within a Neurosciences Critical Care Unit, provides the resource required to study critically ill patients after brain injury from initial ictus through recovery from coma and rehabilitation to final outcome. Methods to define cerebral ischemia in the context of altered cerebral oxidative metabolism have been developed, traditional therapies for intracranial hypertension re-evaluated and bedside monitors cross-validated. New modelling and analytical approaches have been developed.

Animals↗
PubMed2005

Survey of caffeine levels in retail beverages in Portugal.

The caffeine content of 85 retail beverage samples purchased from local supermarkets between 1995 and 2004 was determined. The potential intake of caffeine through the consumption of these beverages (but excluding coffee) was estimated for students of the University of Coimbra, Portugal. The caffeine content of the beverages ranged from 47.5 to 282.5 mg l(-1) for teas, from 20.1 to 47.2 mg l(-1) for tea extracts samples, and from 80.7 to 168.7 mg l(-1) for cola soft drinks. Caffeine was not completely absent from caffeine-free colas, and energy drinks had a far greater caffeine content than regular drinks, ranging from 21 to 2175 mg l(-1). Soft drinks were consumed by 72% of the individuals, although 14% of the survey participants did not drink any of the different types of the beverages studied. Contrary to expectations for this age group, no consumptions of energy drinks was reported. Daily caffeine intake was estimated to range from 4.7 to 200 mg day(-1), but with only 5% reporting a daily intake around 200 mg caffeine. Cola-type beverages were an important dietary source of caffeine for the population studied. Statistical differences in the caffeine intake between the male and female populations were found, with p = 0.014, being higher for the male population. Of the beverages studied, cola-type drinks showed statistical differences for the male population, p = 0.03, and tea showed statistical differences for female population p = 0.013, respectively.

Adult↗
PubMed2004

Determination of organochlorine pesticide residues in honey from the central zone of Portugal and the Valencian community of Spain.

In this study nine organochlorine pesticide residues (alpha-, beta-, and gamma-hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), aldrin, p,p'-DDE, p,p'-DDD, o,p'-DDT, and p,p'-DDT) in forty nine samples of honey collected from markets of Portugal and Spain during 2001 and 2002, respectively, were evaluated. For this evaluation, three analytical procedures were studied. The analytical procedure, based on LLE extraction with ethyl acetate followed by gas chromatography-electron-capture detection (GC-ECD) for quantification, and mass spectrometry (GC-MS) for confirmation, has been selected. Recoveries of spiked samples ranged from 68%, for beta-HCH, and 126% for p,p'-DDT, for fortification levels between 10 and 100 microg/kg, and 64%, for alpha-HCH, and 143% for gamma-HCH for fortification levels between 20 and 200 microg/kg. Limits of quantification, using GC-ECD, were from 0.01 and 0.10mg/kg, and limits of detection between 0.001 and 0.02 mg/kg. Fourteen Valencian samples were contaminated, containing residues of HCB or/and HCH isomers. The frequency of detection was 56% for Spanish samples. In Portugal, 23 samples were contaminated, what means 95.8%. In Spanish samples, concentrations range from nd to 0.03 mg/kg for HCB, and nd to 2.24 mg/kg for HCH-total. The mean concentration and standard deviation were 0.017+/-0.011 mg/kg for HCB, and 0.579+/-0.747 mg/kg for HCH-total, contributing the gamma isomer with the highest values. The samples from Portugal showed higher levels. Levels of HCB ranged from nd to 0.39 mg/kg. HCH-total ranged from nd to 4.86 mg/kg, and DDT-total from nd to 0.658 mg/kg. Mean concentration and standard deviation were 0.09+/-0.116 mg/kg for HCB, 1.357+/-1.30 mg/kg for HCH-total, and 0.143+/-0.193 mg/kg for DDT-total.

Chromatography, Gas↗
PubMed2004

Key amino acids located within the transmembrane domains 5 and 7 account for the pharmacological specificity of the human V1b vasopressin receptor.

In mammals, the vasopressin V(1b) receptor (V(1b)-R) is known to regulate ACTH secretion and, more recently, stress and anxiety. The characterization of the molecular determinant responsible for its pharmacological selectivity was made possible by the recent discovery of the first V(1b) antagonist, SSR149415. Based upon the structure of the crystallized bovine rhodopsin, we established a three-dimensional molecular model of interaction between the human V(1b)-R (hV(1b)-R) and SSR149415. Four amino acids located in distinct transmembrane helices (fourth, fifth, and seventh) were found potentially responsible for the hV(1b)-R selectivity. To validate these assumptions, we selectively replaced the leucine 181, methionine 220, alanine 334, and serine 338 residues of hV(1a)-R by their corresponding amino acids present in the hV(1b)-R (phenylalanine 164, threonine 203, methionine 324, and asparagine 328, respectively). Four mutants, which all exhibited nanomolar affinities for vasopressin and good coupling to phospholipase C pathway, were generated. hV(1a) receptors mutated at position 220 and 334 exhibited striking increase in affinity for SSR149415 both in binding and phospholipase C assays at variance with the hV(1a)-R modified at position 181 or 338. In conclusion, this study provides the first structural features concerning the hV(1b)-R and highlights the role of few specific residues in its pharmacological selectivity.

Amino Acid Sequence↗
PubMed2004

Population dietary habits and physical activity modification with age.

OBJECTIVE: The aim of the present study was to analyse the relation between age and both dietary habits and leisure-time physical activity, and to determine nutrient inadequacy of aged groups in our population. DESIGN: Cross-sectional study. SETTING: A random sample of the 25-74-y-old population of Gerona, Spain. SUBJECTS: A total of 838 men and 910 women were selected from among the general population according to the 1991 census. OUTCOME MEASURES: Analysis of dietary habits, including amount and type of alcohol consumption, and detailed evaluation of leisure-time physical activity. RESULTS: Nutrient densities of carbohydrates, vitamin B(1), vitamin B(12), vitamin C, vitamin E, folate, potassium, iron, magnesium, copper, and dietary fiber increased significantly (P<0.05) with age in both genders, whereas an inverse trend was observed for total fat, saturated fatty acids, cholesterol, and sodium. Multiple linear regression analysis revealed a direct association of healthy dietary habits, characterized through a composite dietary score, with age after adjusting for several confounders both in men and women (P<0.001). This score was composed of folate, vitamin C, vitamin E, beta-carotene, dietary fibre, cholesterol, saturated fatty acids, and sodium. In all, 29 and 10% of male and female subjects aged 65-74 y, respectively, reported inadequate intakes of six or more of 16 nutrients. Total leisure-time physical activity increased with age in men (P<0.002), and was not different among female age groups. CONCLUSION: Dietary behaviours and levels of physical activity spent during leisure time indicate a healthy lifestyle of the aged men and women in the present population. Nutrient inadequacy observed in some aged men and women, however, deserves particular intervention of health-care programmes for this growing part of our society.

Adult↗
PubMed2004

Antibiotic residues in edible tissues and antibiotic resistance of faecal Escherichia coli in pigs from Portugal.

The aims were to provide data on antibiotic residues in pig tissues and the trends in the occurrence of antibiotic resistance in Escherichia coli (a commensal bacteria that can colonize the intestinal tract of humans and animals) isolated from the animals studied. Muscle and kidney samples collected from freshly slaughtered pigs were tested for the presence of antibiotic residues using rapid screening tests. Ninety muscle and 90 kidney samples from the same animals, collected in the slaughterhouse of the central region of Portugal, were screened by microbial tests and only six samples did not fulfil the European Community regulations concerning maximum residue limits. When a more sensitive method was used for the detection of sulphamethazine, 36% of the animals contained residues of the antibiotic. This indication of a larger antibiotic occurrence than anticipated was confirmed by studying the susceptibility of their enteric E. coli. In all the animal faeces studied (n = 60), E. coli isolates resistant to amoxycillin, tetracyclines and sulphonamides were found. The majority of the faecal samples demonstrated a high degree of E. coli resistant to sulphonamides and tetracyclines, respectively 88% and 85%. These data raise important questions about the relevance of the detection of antibiotic residues as the only method to establish the quality and safety of animal products for human consumption.

Amoxicillin↗
PubMed2004

The discovery of novel vasopressin V1b receptor ligands for pharmacological, functional and structural investigations.

Until recently, pharmacological studies dealing with vasopressin receptor isoforms were severely hampered by the lack of selective agonists or antagonists that recognize the pituitary V(1b) vasopressin receptor. By contrast, many selective vasopressin-related compounds are available for characterization of the vasopressor (V(1a)) or antidiuretic (V(2)) vasopressin receptor subtypes. Recently, SSR149415, a selective nonpeptide molecule, was discovered with nanomolar affinity for mammalian V(1b) receptors and good selectivity for the other vasopressin and oxytocin receptor isoforms. This molecule exhibits potent antagonist properties both in vitro and in vivo. We also designed synthetic peptides derived from [deaminocysteine(1),arginine(8)]vasopressin (dAVP), modified in position 4 by various amino acid residues. Some of these, d[cyclohexylalanine(4)]AVP or d[lysine(4)]AVP, have a high affinity and an excellent selectivity for the human V(1b) receptor subtype. However, they exhibit a mixed V(1b)/V(2) pharmacological profile for the rat vasopressin receptor isoforms. Whatever the species considered, these peptides behave as agonists both in bioassays performed in vitro and in vivo. The d[cyclohexylalanine(4)]AVP was tritiated and represents the first selective radiolabelled ligand available for studying the human V(1b) receptors. The discovery of these new selective V(1b) agonists and V(1b) antagonist allows an accurate pharmacological characterization of all the vasopressin receptor isoforms. As emphasized in this review, attention to the vasopressin and oxytocin receptor species differences is of critical importance in studies with all vasopressin and oxytocin ligands.

Animals↗
PubMed2001

Variables associated with fibrinogen in a population-based study: interaction between smoking and age on fibrinogen concentration.

The aim of the study was to assess the association between fibrinogen and other cardiovascular risk factors. A cross-sectional population-based study in Gerona (Spain) was designed, 1544 subjects (747 men, 797 women) participated. Anthropometric measurements, blood pressure and blood samples were obtained. Fibrinogen was measured by a coagulometric method. Smoking habits, alcohol consumption and physical activity practice were recorded by questionnaires. Fibrinogen was directly related to age, body mass index (BMI) and female gender and inversely to alcohol and moderate-heavy physical activity practice. Fibrinogen was also higher in men and young women who smoked. In the multivariate analysis, age (regression coefficient (RC): 1.33; standard error (SE): 0.13; unit = 1 year), female gender (RC: 12.24; SE: 3.56) and BMI (RC: 1.83; SE: 0.39; unit = 1 kg/m2) were directly associated with fibrinogen, whereas alcohol (RC: -0.04; SE: 0.01; unit = 1 g/d) was inversely associated. A statistically significant interaction between smoking and age was observed. Age was the strongest variable associated with fibrinogen and modifies the association between smoking and fibrinogen; the magnitude of this association increases with age.

Adult↗
PubMed2001

Use of a three-day estimated food record, a 72-hour recall and a food-frequency questionnaire for dietary assessment in a Mediterranean Spanish population.

AIM: To assess the validity and the short-term reproducibility of a semi-quantitative, self-administrated food frequency questionnaire and a structured 72-hour recall in a Mediterranean Spanish population. METHODS: 44 free-living volunteers participated in the study. Macronutrient, vitamin and mineral intake, recorded on the food frequency questionnaire and the structured 72-h recall were compared with intakes derived from a three-day food record (reference method). Validity of the dietary assessment methods was further assessed by comparing urinary nitrogen, plasma vitamin C, plasma beta-carotene and whole blood glutathione peroxidase activity levels with the corresponding nutrient intakes from the questionnaires. The food frequency questionnaire and the 72-h recall were administered twice to assess the short term reproducibility. RESULTS: Pearson's correlation coefficients between urinary nitrogen, plasma vitamin C, plasma beta-carotene and whole blood glutathione peroxidase activity levels and the reported nitrogen, vitamin C, beta-carotene and selenium intakes were 0.26, 0.53, 0.17, 0.26 for the food frequency questionnaire; 0.41, 0.09, 0.34, 0.42 for the structured 72-h recall and 0.50, 0.54, 0.44, 0.38 for the three-day food record, respectively. The short term reproducibility of analysed nutrient intake showed average intra-class correlation coefficients of 0.91 and 0.69 for the food frequency questionnaire and the structured 72-h recall irrespectively. CONCLUSION: The food frequency questionnaire and the structured 72-h recall provide valid estimates of nutrient intake and could be used for dietary assessments.

Adult↗
PubMed1999

Relationship of therapeutic improvements and 28-day case fatality in patients hospitalized with acute myocardial infarction between 1978 and 1993 in the REGICOR study, Gerona, Spain. The REGICOR Investigators.

BACKGROUND: The aim of this study was to analyze 28-day case fatality trends between 1978 and 1993 among hospitalized acute myocardial infarction (AMI) patients in the REGICOR registry, Gerona, Spain, and relate them to thrombolytic and antiplatelet drug use and changes in patient characteristics. METHODS AND RESULTS: A total of 2053 consecutive patients 25 to 74 years of age with a first Q-wave AMI admitted to the reference hospital between 1978 and 1993 were registered. Clinical characteristics and patient management were recorded. Four 4-year periods were considered: 1978 to 1981, 1982 to 1985 (prethrombolytic therapy), 1986 to 1989 (thrombolytic and antiplatelet drugs introduced), and 1990 to 1993 (thrombolytic and antiplatelet drugs used routinely). The end point was death at 28 days. Case fatality at 28 days decreased 6% per year between 1978 and 1993. A logistic model adjusted for comorbidity and severity showed the last 3 periods to present a steep decrease in the OR of death at 28 days: 0.86 (95% CI, 0.52 to 1.41), 0.59 (95% CI, 0.35 to 0.99), and 0.40 (95% CI, 0.24 to 0.69), respectively, compared with the first period. After 1986, 85.7% of the 112 lives saved could be attributed to the use of antiplatelet and thrombolytic drugs. Adjusted relative risk reduction was 56.0% for antiplatelet drugs, 34.1% for thrombolytic drugs, and 77.9% for the 2 combined. CONCLUSIONS: Our results strongly suggest that new therapies introduced since 1986 have contributed to the decrease in 28-day case fatality of patients admitted with a first Q-wave AMI. This decrease could be attributable mainly to the use of antiplatelet and thrombolytic drugs. These findings should encourage the routine use of thrombolytic and antiplatelet drugs and particularly their combination in the acute phase of AMI.

Adult↗
PubMed1998

Platelet glycoprotein IIb/IIIa genetic polymorphism is associated with plasma fibrinogen levels in myocardial infarction patients. The REGICOR Investigators.

Fibrinogen is the major ligand of platelet glycoprotein IIb/IIIa platelet receptor. Genes coding for platelet fibrinogen receptor glycoprotein IIb/IIIa are polymorphic. The PLA alloantigen has two antigenic determinants, PLA1 and PLA2, located in a 17-23 kD fragment of glycoprotein IIIa. We analyzed whether PLA genotype has any effect on plasma fibrinogen concentration and investigated if the effect has different magnitude in myocardial infarction patients compared with subjects free of angina or myocardial infarction. One hundred sixteen consecutive patients who suffered a myocardial infarction and 136 subjects recruited by random sampling from the local census were included in the study. PLA genotype distribution and allele frequencies in patients did not significantly differ from those in the control group. Mean fibrinogen concentration tended to be higher in controls with genotype PLA1PLA1 than in those with genotype PLA1PLA2 or PLA2PLA2, and in patients this difference reached statistical significance (p < 0.001). We conclude that the PLA polymorphism may be in linkage disequilibrium with another functional mutation in or near the promoter area of the fibrinogen gene or even in another gene, which controls the production or the clearance of fibrinogen.

Chi-Square Distribution↗
PubMed1998

[Anthropometric and dietary determinants of blood levels of HDL cholesterol in a population-based study. The REGICOR study. Researchers of the REGICOR study].

OBJECTIVES: The aim of the present study was to identify dietary and anthropometric factors influencing HDL cholesterol levels in the region of Girona. POBLATION AND METHODS: A cross-sectional study was designed with random recruitment and 798 men and 862 women were included. Anthropometric variables were collected, the energy expenditure in physical activity was calculated and a dietary questionnaire was supplied in order to obtain nutritional data. Furthermore, lipid levels and lipoprotein concentrations were determined. RESULTS: Significant differences were found in serum triglycerides, body mass index, glucose levels and alcohol intake between the upper and the lower tertils of HDL cholesterol in both men and women. In men, energy expenditure in physical activity was significantly associated with HDL cholesterol levels, as well as total fat and monounsaturated fat. In women, together with the waist-to-hip ratio and fasted glycemia, vitamin C was the dietary factor positively associated with HDL cholesterol levels. CONCLUSIONS: Moderate alcohol intake, physical activity, vitamin C consumption and optimizing body weight strongly contribute to increased HDL cholesterol levels in our region.

Adult↗