BackgroundHuman plasma and serum are widely used matrices in clinical and biological studies. However, different collecting procedures and the coagulation cascade influence concentrations of both proteins and metabolites in these matrices. The effects on metabolite concentration profiles have not been fully characterized.Methodology/Principal FindingsWe analyzed the concentrations of 163 metabolites in plasma and serum samples collected simultaneously from 377 fasting individuals. To ensure data quality, 41 metabolites with low measurement stability were excluded from further analysis. In addition, plasma and corresponding serum samples from 83 individuals were re-measured in the same plates and mean correlation coefficients (r) of all metabolites between the duplicates were 0.83 and 0.80 in plasma and serum, respectively, indicating significantly better stability of plasma compared to serum (p = 0.01). Metabolite profiles from plasma and serum were clearly distinct with 104 metabolites showing significantly higher concentrations in serum. In particular, 9 metabolites showed relative concentration differences larger than 20%. Despite differences in absolute concentration between the two matrices, for most metabolites the overall correlation was high (mean r = 0.81±0.10), which reflects a proportional change in concentration. Furthermore, when two groups of individuals with different phenotypes were compared with each other using both matrices, more metabolites with significantly different concentrations could be identified in serum than in plasma. For example, when 51 type 2 diabetes (T2D) patients were compared with 326 non-T2D individuals, 15 more significantly different metabolites were found in serum, in addition to the 25 common to both matrices.Conclusions/SignificanceOur study shows that reproducibility was good in both plasma and serum, and better in plasma. Furthermore, as long as the same blood preparation procedure is used, either matrix should generate similar results in clinical and biological studies. The higher metabolite concentrations in serum, however, make it possible to provide more sensitive results in biomarker detection.

ObjectivesTo estimate the national prevalence of rheumatic and musculoskeletal diseases (RMDs) in the adult Portuguese population and to determine their impact on health-related quality of life (HRQoL), physical function, anxiety and depression.MethodsEpiReumaPt is a national health survey with a three-stage approach. First, 10 661 adult participants were randomly selected. Trained interviewers undertook structured face-to-face questionnaires that included screening for RMDs and assessments of health-related quality of life, physical function, anxiety and depression. Second, positive screenings for ≥1 RMD plus 20% negative screenings were invited to be evaluated by a rheumatologist. Finally, three rheumatologists revised all the information and confirmed the diagnoses according to validated criteria. Estimates were computed as weighted proportions, taking the sampling design into account.ResultsThe disease-specific prevalence rates (and 95% CIs) of RMDs in the adult Portuguese population were: low back pain, 26.4% (23.3% to 29.5%); periarticular disease, 15.8% (13.5% to 18.0%); knee osteoarthritis (OA), 12.4% (11.0% to 13.8%); osteoporosis, 10.2% (9.0% to 11.3%); hand OA, 8.7% (7.5% to 9.9%); hip OA, 2.9% (2.3% to 3.6%); fibromyalgia, 1.7% (1.1% to 2.1%); spondyloarthritis, 1.6% (1.2% to 2.1%); gout, 1.3% (1.0% to 1.6%); rheumatoid arthritis, 0.7% (0.5% to 0.9%); systemic lupus erythaematosus, 0.1% (0.1% to 0.2%) and polymyalgia rheumatica, 0.1% (0.0% to 0.2%). After multivariable adjustment, participants with RMDs had significantly lower EQ5D scores (β=−0.09; p<0.001) and higher HAQ scores (β=0.13; p<0.001) than participants without RMDs. RMDs were also significantly associated with the presence of anxiety symptoms (OR=3.5; p=0.006).ConclusionsRMDs are highly prevalent in Portugal and are associated not only with significant physical function and mental health impairment but also with poor HRQoL, leading to more health resource consumption. The EpiReumaPt study emphasises the burden of RMDs in Portugal and the need to increase RMD awareness, being a strong argument to encourage policymakers to increase the amount of resources allocated to the treatment of rheumatic patients.

Transthyretin (TTR) belongs to a group of proteins, which includes thyroxine-binding globulin and albumin, that bind to and transport thyroid hormones in the blood. TTR is also indirectly implicated in the carriage of vitamin A through the mediation of retinol-binding protein (RBP). It was first identified in 1942 in human serum and cerebrospinal fluid and was formerly called prealbumin for its ability to migrate faster than serum albumin on electrophoresis of whole plasma. It is a single polypeptide chain of 127 amino acids (14,000 Da) and is present in the plasma as a tetramer of noncovalently bound monomers. The major sites of synthesis of TTR in eutherian mammals, marsupials, and birds are the liver and choroid plexus but in reptiles it is synthesised only in the choroid plexus. The observation that TTR is strongly expressed in the choroid plexus but not in the liver of the stumpy-tailed lizard and the strong conservation of expression in the choroid plexus from reptiles to mammals have been taken as evidence to suggest that extrahepatic synthesis of TTR evolved first. The identification and cloning of TTR from the liver of an amphibian, Rana catesbeiana, and a teleost fish, Sparus aurata, and its absence from the choroid plexus of both species suggest an alternative model for its evolution. Protein modelling studies are presented that demonstrate differences in the electrostatic characteristics of the molecule in human, rat, chicken, and fish, which may explain why, in contrast to TTR from human and rat, TTR from fish and birds preferentially binds triiodo-L-thyronine.

Side-chain modeling has a widespread application in many current methods for protein tertiary structure determination, prediction, and design. Of the existing side-chain modeling methods, rotamer-based methods are the fastest and most efficient. Classically, a rotamer is conceived as a single, rigid conformation of an amino acid sidechain. Here, we present a flexible rotamer model in which a rotamer is a continuous ensemble of conformations that cluster around the classic rigid rotamer. We have developed a thermodynamically based method for calculating effective energies for the flexible rotamer. These energies have a one-to-one correspondence with the potential energies of the rigid rotamer. Therefore, the flexible rotamer model is completely general and may be used with any rotamer-based method in substitution of the rigid rotamer model. We have compared the performance of the flexible and rigid rotamer models with one side-chain modeling method in particular (the self-consistent mean field theory method) on a set of 20 high quality crystallographic protein structures. For the flexible rotamer model, we obtained average predictions of 85.8% for chi1, 76.5% for chi1+2 and 1.34 A for root-mean-square deviation (RMSD); the corresponding values for core residues were 93.0%, 87.7% and 0.70 A, respectively. These values represent improvements of 7.3% for chi1, 8.1% for chi1+2 and 0.23 A for RMSD over the predictions obtained with the rigid rotamer model under otherwise identical conditions; the corresponding improvements for core residues were 6.9%, 10.5% and 0.43 A, respectively. We found that the predictions obtained with the flexible rotamer model were also significantly better than those obtained for the same set of proteins with another state-of-the-art side-chain placement method in the literature, especially for core residues. The flexible rotamer model represents a considerable improvement over the classic rigid rotamer model. It can, therefore, be used with considerable advantage in all rotamer-based methods commonly applied to protein tertiary structure determination, prediction, and design and also in predictions of free energies in mutational studies.

BackgroundThe World Mental Health Survey Initiative was designed to evaluate the prevalence, the correlates, the impact and the treatment patterns of mental disorders. This paper describes the rationale and the methodological details regarding the implementation of the survey in Portugal, a country that still lacks representative epidemiological data about psychiatric disorders.MethodsThe World Mental Health Survey is a cross-sectional study with a representative sample of the Portuguese population, aged 18 or older, based on official census information. The WMH-Composite International Diagnostic Interview, adapted to the Portuguese language by a group of bilingual experts, was used to evaluate the mental health status, disorder severity, impairment, use of services and treatment. Interviews were administered face-to-face at respondent’s dwellings, which were selected from a nationally representative multi-stage clustered area probability sample of households. The survey was administered using computer-assisted personal interview methods by trained lay interviewers. Data quality was strictly controlled in order to ensure the reliability and validity of the collected information.ResultsA total of 3,849 people completed the main survey, with 2,060 completing the long interview, with a response rate of 57.3%. Data cleaning was conducted in collaboration with the WMHSI Data Analysis Coordination Centre at the Department of Health Care Policy, Harvard Medical School. Collected information will provide lifetime and 12-month mental disorders diagnoses, according to the International Classification of Diseases and to the Diagnostic and Statistical Manual of Mental Disorders.ConclusionsThe findings of this study could have a major influence in mental health care policy planning efforts over the next years, specially in a country that still has a significant level of unmet needs regarding mental health services organization, delivery of care and epidemiological research.

RESUMOIntrodução: A esperança de vida está a aumentar em Portugal, contudo desconhece-se o estado de saúde dos idosos. Pretende-se determinar a prevalência de multimorbilidade, caracterizar estilos de vida e outros fatores relacionados com a saúde dos idosos. Material e Métodos: Efetuou-se uma avaliação transversal a 2393 adultos com 65 ou mais anos de idade, da coorte EpiDoC que é constituída por uma amostra representativa da população portuguesa. Os inquiridos responderam a um questionário estruturado através de uma entrevista telefónica, tendo-se recolhido dados socioeconómicos demográficos, estilo de vida, doenças crónicas e consumo de recursos em saúde. Análise de clusters foi realizada para a identificação de padrões alimentares. Efetuou-se análise descritiva e analítica para estimar a prevalência de multimorbilidade e fatores associados. ABSTRACT Introduction: Portuguese adults have a long lifespan, but it is unclear whether they live a healthy life in their final years. We aimed to determine the prevalence of multimorbidity and characterize lifestyle and other health outcomes among older Portuguese adults. Material and Methods:We performed a cross-sectional evaluation of 2393 adults, aged 65 and older, during the second wave of follow-up of the EpiDoC cohort, a population-based study involving long-term follow-up of a representative sample of the Portuguese population. Subjects completed a structured questionnaire during a telephone interview. Socioeconomic, demographic, lifestyle behaviours, chronic diseases, and health resources consumption were assessed. Cluster analysis was done to identify dietary patterns. Descriptive and analytic analysis was performed to estimate multimorbidity prevalence and its associated factors. Results: Multimorbidity prevalence among older adults was 78.3%, increased with age strata (72.8% for 65 -69 years to 83.4% for ≥ 80 years), and was highest in Azores (84.9%) and Alentejo (83.6%). The most common chronic diseases were hypertension (57.3%), rheumatic disease (51.9%), hypercholesterolemia (49.4%), and diabetes (22.7%). Depression symptoms were frequent (11.8%) and highest in the oldest strata. The mean health-related quality of life (EQ-5D-3L) score was 0.59 ± 0.38. Hospitalization in the previous 12 months was reported by 25.8% of individuals. Overall, 66.6% of older adults were physically inactive. 'Fruit and vegetables dietary pattern' was followed by 85.4% of individuals; however, regional inequalities were found (69% in Azores). Obesity prevalence was 22.3% overall and was highest among Azoreans (33%). Conclusion:The high prevalence of multimorbidity, combined with unhealthy lifestyle behaviours, suggests that the elderly population constitutes a vulnerable group warranting dedicated intervention.

The respiratory chain of the thermohalophilic bacterium Rhodothermus marinus contains a novel complex III and a high potential iron-sulfur protein (HiPIP) as the main electron shuttle (Pereira et al., Biochemistry 38 (1999) 1268-1275 and 1276-1283). In this paper, one of the terminal oxidases expressed in this bacterium is extensively characterised. It is a caa3-type oxidase, isolated with four subunits (apparent molecular masses of 42, 19 and 15 kDa and a C-haem containing subunit of 35 kDa), which has haems of the A(s) type. This oxidase is capable of using TMPD and horse heart cytochrome c as substrates, but has a higher turnover with HiPIP, being the first example of a HiPIP:oxygen oxidoreductase. The oxidase has unusually low reduction potentials of 260 (haem C), 255 (haem A) and 180 mV (haem A3). Subunit I of R. marinus caa3 oxidase has an overall significant homology with the subunits I of the COX type oxidases, namely the metal binding sites and most residues considered to be functionally important for proton uptake and pumping (K- and D-channels). However, a major difference is present: the putative essential glutamate (E278 in Paraccocus denitrificans) of the D-channel is missing in the R. marinus oxidase. Homology modelling of the R. marinus oxidase shows that the phenol group of a tyrosine residue may occupy a similar spatial position as the glutamate carboxyl, in relation to the binuclear centre. Moreover, sequence comparisons reveal that several enzymes lacking that glutamate have a conserved substitution pattern in helix VI: -YSHPXV- instead of -XGHPEV-. These observations are discussed in terms of the mechanisms for proton uptake and it is suggested that, in these enzymes, tyrosine may play the role of the glutamate in the proton channel.

Resumo Programação é algo extremamente importante e não deveria ser ensinada apenas para estudan