Machine learning techniques to predict the risk of developing diabetic nephropathy: a literature review.

Purpose: Diabetes is a major public health challenge with widespread prevalence, often leading to complications such as Diabetic Nephropathy (DN)-a chronic condition that progressively impairs kidney function. In this context, it is important to evaluate if Machine learning models can exploit the inherent temporal factor in clinical data to predict the risk of developing DN faster and more accurately than current clinical models. Methods: Three different databases were used for this literature review: Scopus, Web of Science, and PubMed. Only articles written in English and published between January 2015 and December 2022 were included. Results: We included 11 studies, from which we discuss a number of algorithms capable of extracting knowledge from clinical data, incorporating dynamic aspects in patient assessment, and exploring their evolution over time. We also present a comparison of the different approaches, their performance, advantages, disadvantages, interpretation, and the value that the time factor can bring to a more successful prediction of diabetic nephropathy. Conclusion: Our analysis showed that some studies ignored the temporal factor, while others partially exploited it. Greater use of the temporal aspect inherent in Electronic Health Records (EHR) data, together with the integration of omics data, could lead to the development of more reliable and powerful predictive models.

Influenza vaccination in older adults and patients with chronic disorders: A position paper from the Portuguese Society of Pulmonology, the Portuguese Society of Diabetology, the Portuguese Society of Cardiology, the Portuguese Society of Geriatrics and Gerontology, the Study Group of Geriatrics of the Portuguese Society of Internal Medicine, and the Portuguese Society of Infectious Diseases and Clinical Microbiology.

Influenza affects millions of people worldwide each year and can lead to severe complications, hospitalizations, and even death, especially among vulnerable populations such as older adults and those with chronic medical conditions. Annual vaccination is considered the most effective measure for preventing influenza and its complications. Despite the widespread availability of influenza vaccines, however, vaccination coverage rates remain suboptimal in several countries. Based on the latest scientific evidence and expert opinions on influenza vaccination in older people and patients with chronic disease, the Portuguese Society of Pulmonology (SPP), the Portuguese Society of Diabetology (SPD), the Portuguese Society of Cardiology (SPC), the Portuguese Society of Geriatrics and Gerontology (SPGG), the Study Group of Geriatrics of the Portuguese Society of Internal Medicine (NEGERMI-SPMI), and the Portuguese Society of Infectious Diseases and Clinical Microbiology (SPDIMC) discussed best practices for promoting vaccination uptake and coverage and drew up several recommendations to mitigate the impact of influenza. These recommendations focus on the efficacy and safety of available vaccines; the impact of influenza vaccination on older adults; patients with chronic medical conditions, namely cardiac and respiratory conditions, diabetes, and immunosuppressive diseases; and health care professionals, optimal vaccination timing, and strategies to increase vaccination uptake and coverage. The resulting position paper highlights the critical role that vaccinations play in promoting public health, raising awareness, and encouraging more people to get vaccinated.

A standard set of person-centred outcomes for diabetes mellitus: results of an international and unified approach.

AIMS: To select a core list of standard outcomes for diabetes to be routinely applied internationally, including patient-reported outcomes. METHODS: We conducted a structured systematic review of outcome measures, focusing on adults with either type 1 or type 2 diabetes. This process was followed by a consensus-driven modified Delphi panel, including a multidisciplinary group of academics, health professionals and people with diabetes. External feedback to validate the set of outcome measures was sought from people with diabetes and health professionals. RESULTS: The panel identified an essential set of clinical outcomes related to diabetes control, acute events, chronic complications, health service utilisation, and survival that can be measured using routine administrative data and/or clinical records. Three instruments were recommended for annual measurement of patient-reported outcome measures: the WHO Well-Being Index for psychological well-being; the depression module of the Patient Health Questionnaire for depression; and the Problem Areas in Diabetes scale for diabetes distress. A range of factors related to demographic, diagnostic profile, lifestyle, social support and treatment of diabetes were also identified for case-mix adjustment. CONCLUSIONS: We recommend the standard set identified in this study for use in routine practice to monitor, benchmark and improve diabetes care. The inclusion of patient-reported outcomes enables people living with diabetes to report directly on their condition in a structured way.

Intensive monitoring of adverse drug events associated with the use of new glucose-lowering drugs: results from an inception cohort study in Portugal.

AIMS: To determine the frequency and the time-course profile of adverse drug events associated with new glucose-lowering drugs in daily practice and to explore factors potentially associated to these events. METHODS: An inception cohort study was implemented. Adults with type 2 diabetes mellitus initiating a dipeptidyl peptidase-4 inhibitor, a glucagon-like peptide-1 receptor agonist or a sodium-glucose co-transporter-2 inhibitor were eligible for inclusion. Data were collected through baseline and follow-up telephone questionnaires, administered at 2 weeks, 3 months and 6 months. Kaplan-Meier curves and log-rank were computed to compare the time to adverse drug event onset. Cox models were used to explore potential factors associated with adverse drug events. RESULTS: A total of 1328 participants were recruited to the study. In all, 1118 adverse drug events were reported (of which 36% were not listed in the summary of product characteristics) by 41% of participants. The median latency time of adverse drug events reported in ≥1% of participants ranged from 0 to 2 days. Glucagon-like peptide-1 receptor agonist and sodium-glucose co-transporter-2 inhibitor subgroups were associated with an increased likelihood of adverse drug event reporting when compared with the dipeptidyl peptidase-4 inhibitor subgroup. A total of 328 glucose-lowering drugs were withdrawn, more than half as a result of an adverse drug event. CONCLUSIONS: More than two-fifths of participants reported an adverse drug event; dipeptidyl peptidase-4 inhibitors led to the highest proportion of unlabelled adverse drug events. Adverse drug event latency time data show that counselling and adverse drug event management should be proactively addressed from treatment initiation. There should be greater focus on prevalent new users of glucose-lowering drugs, who were more complex participants in this study in terms of type 2 diabetes disease, as they were more likely to report an adverse drug event than the incident new users.

Atividade física, autoestima e depressão em idosos / Actividad física, autoestima y depresión en adultos mayores / Physical activity, self-esteem and depression in older adults

A presente investigação pretende verificar se a prática de atividade física influencia a autoestima e os níveis de depressão em idosos. Constituíram a amostra 215 indivíduos (61 do sexo masculino e 154 do sexo feminino), praticantes e não praticantes de atividade física, com idades compreendidas entre os 60 e os 100 anos. As variáveis do estudo foram avaliadas através da aplicação de dois instrumentos, a Escala de Avaliação de Autoestima de Rosenberg e a Escala de Ansiedade, Depressão e Stresse (DASS- 21). Os resultados demonstraram que os idosos que praticam atividade física revelam níveis de autoestima elevados e níveis de depressão reduzidos. Constatou-se que a autoestima diminui com a idade, enquanto os sintomas depressivos aumentam. O sexo, a situação conjugal, a escolaridade e a institucionalização alcançaram significância estatística na escala de autoestima. Foram os idosos do sexo masculino, com companheiro, com maior nível de escolaridade e não institucionalizados que reportaram níveis superiores. Concluiu-se que à medida que a frequência da prática de atividade física aumenta, os níveis de autoestima tornam-se mais acentuados, enquanto os níveis de depressão diminuem. Relativamente à relação entre a autoestima e a depressão, verificou-se um correlato negativo com efeito pequeno (AU)

Esta investigación tuvo como objetivo evaluar si la actividad física regular afecta a los niveles de autoestima y depresión en los adultos mayores. Constituyeron la muestra 215 personas (61 hombres y 154 mujeres), practicantes y no practicantes de actividad física, de entre 60 y 100 años. Las variables de estudio fueron evaluados mediante la aplicación de dos instrumentos, la ‘Escala de Autoestima de Rosenberg’ y la ‘Escala de Ansiedad, Depresión y Estrés (DASS-21)’. Los resultados mostraron que las personas mayores que practican actividad física revelan altos niveles de autoestima y niveles de depresión más bajos. Se encontró que la autoestima disminuye con la edad, mientras que los síntomas depresivos aumentan. El sexo, el estado civil, la educación y la institucionalización alcanzaron significación estadística en la escala de autoestima. Eran las personas mayores de sexo masculino, con pareja, con mayores niveles de educación y no institucionalizada los que reportaron niveles más altos. Se concluyó que a medida que aumenta la frecuencia con la que se practica actividad física, se incrementan las puntuaciones obtenidas en los niveles de autoestima, mientras las puntuaciones en depresión disminuyen. En cuanto a la relación entre la autoestima y la depresión, hay una correlación negativa con poco efecto (AU)

This research aims to verify whether physical activity influences the levels of self-esteem and depression in the elderly. The sample is constituted by 215 subjects (61 males and 154 females), practitioners and non-practitioners of physical activity, aged 60 to 100 years. The study variables were evaluated by applying two instruments, the Rosenberg Self-Esteem Scale and the Anxiety, Depression and Stress Scale (DASS-21). The results showed that elderly people who practice physical activity reveal high levels of self-esteem and lower levels of depression. It was found that self-esteem decreases with age, while depressive symptoms increase. Gender, marital status, educational level and institutionalization reached statistical significance in the self-esteem scale. Were elderly male, with partners, higher educational level and non-institutionalized who reported higher levels. We conclude that as the frequency of physical activity increases, levels of self-esteem become more accentuated, while levels of depression decrease. Regarding the relationship between self-esteem and depression, there was a negative correlate with small effect (AU)

Diabetes hinders community-acquired pneumonia outcomes in hospitalized patients.

OBJECTIVES: This study aimed to estimate the prevalence of diabetes mellitus (DM) in hospitalized patients with community-acquired pneumonia (CAP) and its impact on hospital length of stay and in-hospital mortality. RESEARCH DESIGN AND METHODS: We carried out a retrospective, nationwide register analysis of CAP in adult patients admitted to Portuguese hospitals between 2009 and 2012. Anonymous data from 157 291 adult patients with CAP were extracted from the National Hospital Discharge Database and we performed a DM-conditioned analysis stratified by age, sex and year of hospitalization. RESULTS: The 74 175 CAP episodes that matched the inclusion criteria showed a high burden of DM that tended to increase over time, from 23.7% in 2009 to 28.1% in 2012. Interestingly, patients with CAP had high DM prevalence in the context of the national DM prevalence. Episodes of CAP in patients with DM had on average 0.8 days longer hospital stay as compared to patients without DM (p<0.0001), totaling a surplus of 15 370 days of stay attributable to DM in 19 212 admissions. In-hospital mortality was also significantly higher in patients with CAP who have DM (15.2%) versus those who have DM (13.5%) (p=0.002). CONCLUSIONS: Our analysis revealed that DM prevalence was significantly increased within CAP hospital admissions, reinforcing other studies' findings that suggest that DM is a risk factor for CAP. Since patients with CAP who have DM have longer hospitalization time and higher mortality rates, these results hold informative value for patient guidance and healthcare strategies.

Glycaemic threshold for diabetes-specific retinopathy among individuals from Saudi Arabia, Algeria and Portugal.

We studied the glycaemic threshold and prevalence of diabetic retinopathy in screen-detected diabetes in Saudi Arabia, Algeria and Portugal. The prevalence of diabetes-specific retinopathy started to increase at an HbA1c level of 6-6.4% (42-47 mmol/mol) and in individuals with HbA(1c) >7.0% the prevalence was 6.0%.

Prevalence of subclinical ketosis and relationships with postpartum diseases in European dairy cows.

Subclinical ketosis (SCK) is defined as concentrations of ß-hydroxybutyrate (BHBA) ≥ 1.2 to 1.4 mmol/L and it is considered a gateway condition for other metabolic and infectious disorders such as metritis, mastitis, clinical ketosis, and displaced abomasum. Reported prevalence rates range from 6.9 to 43% in the first 2 mo of lactation. However, there is a dearth of information on prevalence rates considering the diversity of European dairy farms. The objectives of this study were to (1) determine prevalence of SCK, (2) identify thresholds of BHBA, and (3) study their relationships with postpartum metritis, clinical ketosis, displaced abomasum, lameness, and mastitis in European dairy farms. From May to October 2011, a convenience sample of 528 dairy herds from Croatia, Germany, Hungary, Italy, Poland, Portugal, Serbia, Slovenia, Spain, and Turkey was studied. ß-Hydroxybutyrate levels were measured in 5,884 cows with a handheld meter within 2 to 15 d in milk (DIM). On average, 11 cows were enrolled per farm and relevant information (e.g., DIM, postpartum diseases, herd size) was recorded. Using receiver operator characteristic curve analyses, blood BHBA thresholds were determined for the occurrence of metritis, mastitis, clinical ketosis, displaced abomasum, and lameness. Multivariate binary logistic regression models were built for each disease, considering cow as the experimental unit and herd as a random effect. Overall prevalence of SCK (i.e., blood BHBA ≥ 1.2 mmol/L) within 10 countries was 21.8%, ranging from 11.2 to 36.6%. Cows with SCK had 1.5, 9.5, and 5.0 times greater odds of developing metritis, clinical ketosis, and displaced abomasum, respectively. Multivariate binary logistic regression models demonstrated that cows with blood BHBA levels of ≥ 1.4, ≥ 1.1 and ≥ 1.7 mmol/L during 2 to 15 DIM had 1.7, 10.5, and 6.9 times greater odds of developing metritis, clinical ketosis, and displaced abomasum, respectively, compared with cows with lower BHBA blood levels. Interestingly, a postpartum blood BHBA threshold ≥ 1.1 mmol/L increased the odds for lameness in dairy cows 1.8 (95% confidence interval: 1.3 to 2.5) times. Overall, prevalence of SCK was high between 2 to 15 DIM and SCK increased the odds of metritis, clinical ketosis, lameness, and displaced abomasum in European dairy herds.

A mathematical model of calcium and phosphorus metabolism in two forms of hyperparathyroidism.

Parathyroid hormone (PTH) plays a critical role in calcium and phosphorus metabolism. Interestingly, in two forms of hyperparathyroidism (excessive amount of PTH in the serum), the metabolic disturbances in patients with chronic kidney disease (CKD) significantly differ from those with primary hyperparathyroidism (PHP). Since an intuitive understanding of these PTH-linked regulatory mechanisms are hardly possible, we developed a mathematical model using clinical data (1586 CKD and 40 PHP patients). The model was composed of a set of ordinary differential equations, in which the regulatory mechanism of PTH together with other key factors such as 1,25-Dihydroxyvitamin D (1,25(OH)2D) and calcium was described in the tissues including bone, the kidney, the serum, and the parathyroid glands. In this model, an increase in PTH was induced by its autonomous production in PHP, while PTH in CKD was elevated by a decrease in feedback inhibition of 1,25(OH)2D in the serum, as well as an increase in stimulation by phosphorus in the serum. The model-based analysis revealed characteristic differences in the outcomes of hyperparathyroidism in CKD and PHP. The calcium exchange in bone, for instance, was predicted significantly higher in PHP than CKD. Furthermore, we evaluated the observed and predicted responses to the administration of calcimimetics, a recently developed synthetic drug that modulated efficacy of calcium-sensing receptors. The results herein support the notion that the described model would enable us to pose testable hypotheses about the actions of PTH, providing a quantitative analytical tool for evaluating treatment strategies of PHP and CKD.

First diabetes prevalence study in Portugal: PREVADIAB study.

AIMS: Diabetes is a growing worldwide problem. Ascertaining its prevalence is vital as a starting point to establish and measure the success of health interventions. This study aimed to determine the prevalence of Type 2 diabetes and 'pre-diabetes', defined as impaired fasting glucose and impaired glucose tolerance, in the Portuguese population aged between 20 and 79 years. METHODS: Considering the number of inhabitants between 20 and 79 years old, statistical units were selected that were representative regionally and nationally. The total sample comprised 5167 subjects. National prevalence was calculated. Analyses were performed on all those without previously known diabetes using World Health Organization reference diagnostic criteria. RESULTS: We found a diabetes prevalence of 11.7% (95% confidence interval 10.8-12.6%), with a significant difference between men (14.2%; 95% confidence interval 12.5-15.5%) and women (9.5%; 95% confidence interval 8.5-10.6%). While 6.6% of the subjects had previously been diagnosed with diabetes, 5.1% were undiagnosed. By age groups, 2.4% of the population between 20 and 39 years, 12.6% of people from 40 to 59 years old and 26.3% of those aged between 60 and 79 years had diabetes. Prevalence of 'pre-diabetes' (impaired fasting glucose, impaired glucose tolerance or both) in the population was 23.3%. CONCLUSIONS: Diabetes has a high prevalence in Portugal. If 'pre-diabetes' is also considered, about one-third (34.9%) of the population aged 20-79 years is affected. A greater number of males were found to have diabetes. We detected a high percentage of people with undiagnosed diabetes (43.6%).

Occurrence and distribution of metals in mussels from the Cantabrian coast.

From February 2004 to April 2006, the concentrations of more than 10 metals in mussels (Mytilus galloprovincialis) were measured in 10 stations from Galicia to the Basque Country in 8 different times of sampling. The mean highest concentrations are found for Zn [226.8 microg/g, dry weight (d.w.)] followed by Mn, As, Cu, and Co (between 10 and 25 microg/g d.w.). Lower mean concentrations are found for Se, Cr, Pb, V, and Ni (between 2 and 8 microg/g d.w.) and the lowest are for Cd, Sn, Hg, and Sb (between 0.05 and 1 microg/g d.w.). Among the statistical treatments used, the factor analysis showed a clustering of the mussels according to the geographical location. In addition, the temporal trend of the metal concentrations was studied by means of the Mann-Kendall test. In this sense, some stations showed a decreasing trend in the accumulation of the metallic content. However, there were some local pollution events that could be explained as a consequence of anthropogenic activities. Finally, the effects of the oil spill from the Prestige are discussed based on the experimental Ni/V ratio values obtained from this work and those of the original oil.

Trace metals in oysters, Crassotrea sps., from UNESCO protected natural reserve of Urdaibai: space-time observations and source identification.

The seasonal and spatial variability of trace metal concentrations of oyster tissues (Crassostea sps.) was studied. The samples were collected between 2002 and 2004 along the Urdaibai estuary (Murueta, Kanala and Arteaga). The seasonal influence on some metal concentrations (higher values in spring-summer season than in autumn-winter season) is more pronounced than the local site-specific influence. Furthermore, within each location a significant time-specific dependence on the trace metal concentration variations can be detected. Substantially higher concentrations of Zn (445.5-2,403.3 mg kg(-1)) and Mn (29.4-169.6 mg kg(-1)) were recorded in oysters inhabiting estuarine locations, possibly indicating a markedly higher natural bioavailability at these locations. Principal component analysis demonstrated that oysters could be separated depending on the inhabiting areas: Sn for Murueta, essential metals for Kanala, and Co and Cd for Arteaga sampling points, respectively.

Pleural effusion: what lies underneath?

Malignant mesothelioma is a tumour of serous surfaces mainly arising at the pleura or the peritoneum. The diagnosis encompasses multiple problems as there is no pathognomonic hallmark for the disease, there are multiple histological types and the differentiation from other tumours, such as adenocarcinoma or metastatic pleural disease, can represent quite a challenge. Usually a diagnosis of malignant mesothelioma carries a dismal prognosis with scarce therapeutical options.The present report concerns a patient with a diagnosis of malignant pleural mesothelioma with endobronchial extension. Biopsy specimens were obtained through fibreoptic bronchoscopy and blind needle pleural biopsy. The final diagnosis was only possible after careful histological evaluation with a combination of immunohistochemical markers.

Distribution and bioaccumulation of PAHs in the UNESCO protected natural reserve of Urdaibai, Bay of Biscay.

Along 10 campaigns, from June 2002 to September 2004, the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were measured in sediments and oysters (Crassostrea sp.) taken from four sites in the Unesco protected natural reserve of Urdaibai (Basque Country, Bay of Biscay). Total PAH concentration ranged from 0.7 to 140 microg kg(-1) (dw) in the case of sediments, and from 300 to 1400 microg kg(-1) (dw) in the case of oysters. During this study, the coast of the Bay of Biscay was severely affected by the Prestige oil spill (November 2002). Presumably, as a consequence of this accident, both spatial and temporal variations of the PAHs, as well as the sources of the PAHs were affected by the oil spill, and this effect was observed in the total concentrations and, especially, in several diagnostic ratios and in multivariate data analysis. Finally, both BAF (bioaccumulation factor) and BSAF (biota-sediment accumulation factor) parameters were calculated to conclude that particulate matter seems to be the most favourable uptake pathway of PAHs in oysters from this estuary.

Mercury biomethylation assessment in the estuary of Bilbao (North of Spain).

The relationship between the microbial methylation of mercury and the microbial activities in sediments and water collected from the estuary of Bilbao (North of Spain) was studied in three different sampling points and in two different seasons. Three different cultures were prepared with a sediment slurry to distinguish between biotic and abiotic methylation pathways and the variations of the methylmercury concentration and the variations of the population of total number of bacteria (TDC), anaerobic heterotrophic bacteria (AHB), sulphate-reducing bacteria (SRB) and Desulfovibrio were measured. From this work, it can be concluded that the variation of MeHg concentrations is a result of the methylation/demethylation processes in the sediments, and that the abiotic processes have a negligible contribution to those processes. According to the statistical analysis of the results (partial least squares analysis) a significant statistical correlation was established between methylmercury and the SRB counts.

Comparison of solid phase extraction, saponification and gel permeation chromatography for the clean-up of microwave-assisted biological extracts in the analysis of polycyclic aromatic hydrocarbons.

The feasibility of different clean-up procedures was studied for the determination of polycyclic aromatic hydrocarbons (PAHs) in biota samples such as oysters, mussels and fish liver. In this sense, once the samples were extracted--essentially with acetone and in a microwave system--and before they could be analysed by gas chromatography-mass spectrometry (GC-MS), three different approaches were studied for the clean-up step: solid phase extraction (SPE), microwave-assisted saponification (MAS) and gel permeation chromatography (GPC). The main aim of this work was to maximise the recoveries of PAHs and to minimise the presence of interfering compounds in the last extract. In the case of SPE, Florisil cartridges of 1, 2 and 5 g, and silica cartridges of 5 g were studied. In that case, and with oysters and mussels, microwave-assisted extraction and 5 g Florisil cartridges provided good results. In addition, the concentrations obtained for Standard Reference Material (SRM) NIST 2977 (mussel tissue) were in good agreement with the certified values. In the case of microwave-assisted saponification, the extracts were not as clean as those obtained with 5 g Florisil and this fact lead to overestimate the concentration of the heaviest PAHs. Finally, the cleanest extracts were obtained by GPC. The method was successfully applied to mussels, oysters and hake liver, and the results obtained for NIST 2977 (mussel tissue) were within the confidence interval of the certified reference material for most of the certified analytes.

Simultaneous microwave-assisted extraction of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, phthalate esters and nonylphenols in sediments.

A new method was developed for the simultaneous extraction of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), phthalate esters (PEs), nonylphenols (NPs) and nonylphenol mono- and diethoxylates (NP1EOs and NP2EOs, respectively) in sediment samples by means of a closed microwave system. The extractions were carried out at 21 psi and 80% of microwave power and 15 ml of acetone were used as the common extraction solvent. The filtered extract was further fractionated in two groups using Florisil cartridges: PAHs and PCBs were eluted with n-hexane:toluene (4:1) and the PEs, NPs and ethoxylates were eluted with ethyl acetate. All the compounds were analysed by gas chromatography-mass spectrometry (GC-MS). In case of PAHs and PCBs, the developed method was validated by comparison of the results obtained for the certified reference material NIST 1944 with the certified values. In the absence of a reference material for phthalate esters and nonylphenols, one sediment sample was extracted twice under the optimal conditions in order to check than an exhaustive extraction of the analytes occurred. This method is currently used in the study of the distribution of those organic contaminants in the estuaries of the Bay of Biscay (Spain).

Optimisation of flow-injection-hydride generation inductively coupled plasma spectrometric determination of selenium in electrolytic manganese.

Flow-injection-hydride generation procedure for Se in electrolytic manganese was optimized by means of the experimental design approach. Instrumental variables like power supplied (P), sample (F) and argon (G) flow rates together with chemical variables like NaBH(4) and HCl concentrations were studied. In case of the chemical variables, it was concluded that sodium tetrahydridoborate concentrations higher than 1.0% extinguished the plasma while HCl concentration should always be higher than 0.6moldm(-3). The analysis of effects suggested that all the instrumental variables are significant factors, and the optimum conditions were P=1550W, F=4.75mLmin(-1) and G=0.6mLmin(-1). The influence of Mn was specially studied and it was concluded that the interferences were negligible if Mn is below 2.0gL(-1). In the same sense, the interferences of antimony(III), arsenic(V) and mercury(II) were also considered negligible. Finally, a detection limit of 0.0005% (w/w) was obtained (a repeatability R.S.D. <2.0% for all Se concentrations tried). Some manganese samples were also spiked with different concentrations of Se(IV) and the results demonstrated to be in good statistical agreement with expected values.

Comparison of whole-blood glutathione peroxidase activity, levels of serum selenium, and lipid peroxidation in subjects from the fishing and rural communities of "Rabo de Peixe" village, San Miguel Island, the Azores' Archipelago, Portugal.

The activity of glutathione peroxidase (GSH-Px), serum selenium (Se), and thiobarbituric acid reactive substances (TBARS) were measured in the whole blood of 148 healthy adults aged 20-60 yr from the fishing and rural communities of "Rabo de Peixe," The Azores, Portugal. The subjects did not live in the same household and had different socioeconomic profiles and dietary habits. The serum lipid profile and selected life habits were also considered in this study. No significant differences in the activity of GSH-Px were found in the interpopulation or intrapopulation analyses, classified by age or lipid profile. An age-dependent GSH-Px increase was noted in the younger male (M) subgroups (20-39 yr). The Se levels were higher in fishers (f) of both genders (M, F) than in subjects living in the rural (r) environment: 110+/-25 microg/L (f, M), 89+/-20 microg/L (f, F), 88+/-22 microg/L (r, M) and 80+/-17 microg/L (r, F). In the fishers, but not in the rural population, Se was higher in the males, but it did not show significant variation with age. The levels of TBARS were lower in the f than in the r male group. The Se level was lower and TBARS higher in the hyperlipemic women in the f group, compared to the corresponding controls. Our results suggest that the fishers (mainly men) show a better antioxidant status than that of their rural counterparts, due to differences in dietary habits between the study populations and between genders.