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A previous study demonstrated that rodents on an inclined square platform traveled straight vertically or horizontally and avoided diagonal travel. Through behavior they aligned their head with the horizontal plane, acquiring similar bilateral vestibular cues - a basic requirement for spatial orientation and a salient feature of animals in motion. This behavior had previously been shown to be conspicuous in Tristram's jirds. Here, therefore jirds were challenged by testing their travel behavior on a circular arena inclined at 0°-75°. Our hypothesis was that if, as typical to rodents, the jirds would follow the curved arena wall, they would need to display a compensating mechanism to enable traveling in such a path shape, which involves a tilted frontal head axis and unbalanced bilateral vestibular cues. We found that with the increase in inclination, the jirds remained more in the lower section of the arena (geotaxis). When tested on the steep inclinations, however, their travel away from the arena wall was strictly straight up or down, in contrast to the curved paths that followed the circular arena wall. We suggest that traveling along a circular path while maintaining contact with the wall (thigmotaxis), provided tactile information that compensated for the unbalanced bilateral vestibular cues present when traveling along such curved inclined paths. In the latter case, the frontal plane of the head was in a diagonal posture in relation to gravity, a posture that was avoided when traveling away from the wall.
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Sinais (Psicologia) , Orientação Espacial , Vestíbulo do Labirinto , Animais , Vestíbulo do Labirinto/fisiologia , Orientação Espacial/fisiologia , Masculino , Tato/fisiologia , Postura/fisiologia , Percepção do Tato/fisiologiaRESUMO
OBJECTIVES: We aimed to examine the relationships between body mass index (BMI) and metabolic syndrome (MS) components as a function of age and gender across weight categories. METHODS: This cross-sectional study included 19,328 subjects who participated in a health-screening program. We analyzed 14,093 apparently healthy subjects with a BMI ≥ 18.5 kg/m2 (ranging from 18.5 to 46 kg/m2). RESULTS: At a BMI of 18.5 kg/m2, 16% of subjects had one or more MS components (MS ≥ 1). The number of MS components increased linearly with BMI. The most prevalent components for MS1-4 were hypertension (in men) and increased waist circumference (in women). Among 6391 non-obese subjects with MS = 0, there was a linear increase in blood pressure, glucose, and triglycerides, as well as a decline in high-density lipoprotein cholesterol, as BMI increased. In 2087 subjects with a BMI ≥ 30 kg/m2, a true normometabolic state (MS = 0) was observed in only 7.5%, declining to less than 1% at a BMI ≥ 36 kg/m2 (ATP criteria). Women were metabolically protected relative to men between the ages of 30 and 50 years. CONCLUSIONS: (A) MS components increase linearly with BMI from the lowest normal BMI and continue to increase with age and BMI; (B) metabolically healthy obesity is rare in subjects with a high BMI and declines with age; (C) hypertension is the most common component in men; and (D) in women, MS components are seen at older ages than in men for the same BMI. Metabolic health declines with age and BMI in nearly all subjects with obesity.
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OBJECTIVES: To assess outcomes and complications of conservatively managed humeral diaphyseal fractures in elderly patients, with an emphasis on the subgroup diagnosed with dementia. DESIGN: Retrospective. SETTING: Upper extremity surgery unit at an academic Level I trauma center. PATIENTS/PARTICIPANTS: Consecutive patients 65 years of age and older who were managed conservatively for humeral diaphyseal fractures between 2007 and 2015. INTERVENTION: Conservatively managed humeral diaphyseal fractures. MAIN OUTCOME MEASUREMENTS: Complications and radiographic outcomes. RESULTS: One-hundred twenty-four patients who were conservatively managed for humeral diaphyseal fractures were identified. Their mean age was 77 (65-92) years, 36 (30%) of them were male and 88 (70%) were female. Fifty-seven (46%) patients experienced complications associated with their treatment, and 33 (27%) patients were eventually treated surgically. Seventeen (14%) patients were diagnosed with dementia. This subgroup had 64% fracture-related complications, and all of them were operated (P-value <0.01 compared with age-matched patients among the other 107 participants in the study). CONCLUSION: Conservative management of humeral diaphyseal fractures seems to be associated with greater morbidity in elderly patients, especially in those diagnosed with dementia. Therefore, early surgical treatment should be considered. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.
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Demência , Fraturas do Úmero , Humanos , Masculino , Feminino , Idoso , Tratamento Conservador , Estudos Retrospectivos , Fraturas do Úmero/terapia , Fraturas do Úmero/cirurgia , Úmero , Demência/complicaçõesRESUMO
Animals traveling on a horizontal surface stabilize their head in relation to the substrate in order to gather spatial information and orient. What, however, do they do when traveling on an incline? We examined how three rodent species differing in motor abilities and habitats explore a platform tilted at 0-90°, hypothesizing that they would attempt to maintain bilateral vestibular cues. We found that traveling up or down was mainly straight vertically rather than diagonally, which results in identical bilateral vestibular cues. This was also achieved when traveling horizontally through rotating the head to parallel the horizontal plane. Traveling diagonally up or down was avoided, perhaps due to different bilateral vestibular cues that could hinder orientation. Accordingly, we suggest that maintaining identical bilateral cues is an orientational necessity that overrides differences in motor abilities and habitats, and that this necessity is a general characteristic of animals in motion.
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OBJECTIVE: The vast majority of known proteins have not been experimentally tested even at the level of measuring their expression, and the function of many proteins remains unknown. In order to decipher protein function and examine functional associations, we developed "Cliquely", a software tool based on the exploration of co-occurrence patterns. COMPUTATIONAL MODEL: Using a set of more than 23 million proteins divided into 404,947 orthologous clusters, we explored the co-occurrence graph of 4,742 fully sequenced genomes from the three domains of life. Edge weights in this graph represent co-occurrence probabilities. We use the Bron-Kerbosch algorithm to detect maximal cliques in this graph, fully-connected subgraphs that represent meaningful biological networks from different functional categories. MAIN RESULTS: We demonstrate that Cliquely can successfully identify known networks from various pathways, including nitrogen fixation, glycolysis, methanogenesis, mevalonate and ribosome proteins. Identifying the virulence-associated type III secretion system (T3SS) network, Cliquely also added 13 previously uncharacterized novel proteins to the T3SS network, demonstrating the strength of this approach. Cliquely is freely available and open source. Users can employ the tool to explore co-occurrence networks using a protein of interest and a customizable level of stringency, either for the entire dataset or for a one of the three domains-Archaea, Bacteria, or Eukarya.
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Proteínas , Software , Algoritmos , Bactérias/metabolismo , Biologia Computacional , Proteínas/metabolismoRESUMO
BACKGROUND: The epigenetic age can now be extrapolated from one of several epigenetic clocks, which are based on age-related changes in DNA methylation levels at specific multiple CpG sites. Accelerated aging, calculated from the discrepancy between the chronological age and the epigenetic age, has shown to predict morbidity and mortality rate. We assumed that deconvolution of epigenetic age to its components could shed light on the diversity of epigenetic, and by inference, on inter-individual variability in the causes of biological aging. RESULTS: Using the Horvath original epigenetic clock, we identified several CpG sites linked to distinct genes that quantitatively explain much of the inter-personal variability in epigenetic aging, with CpG sites related to secretagogin and malin being the most variable. We show that equal epigenetic age in different subjects can result from variable contribution size of the same CpG sites to the total epigenetic age. In a healthy cohort, the most variable CpG sites are responsible for accelerated and decelerated epigenetic aging, relative to chronological age. CONCLUSIONS: Of the 353 CpG sites that form the basis for the Horvath epigenetic age, we have found the CpG sites that are responsible for accelerated and decelerated epigenetic aging in healthy subjects. However, the relative contribution of each site to aging varies between individuals, leading to variable personal aging patterns. Our findings pave the way to form personalized aging cards allowing the identification of specific genes related to CpG sites, as aging markers, and perhaps treatment of these targets in order to hinder undesirable age drifting.
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Epigênese Genética , Epigenômica , Envelhecimento/genética , Ilhas de CpG , Metilação de DNA , HumanosRESUMO
The COVID-19 pandemic caused by the SARS-CoV-2 requires a fast development of antiviral drugs. SARS-CoV-2 viral main protease (Mpro, also called 3C-like protease, 3CLpro) is a potential target for drug design. Crystal and co-crystal structures of the SARS-CoV-2 Mpro have been solved, enabling the rational design of inhibitory compounds. In this study we analyzed the available SARS-CoV-2 and the highly similar SARS-CoV-1 crystal structures. We identified within the active site of the Mpro, in addition to the inhibitory ligands' interaction with the catalytic C145, two key H-bond interactions with the conserved H163 and E166 residues. Both H-bond interactions are present in almost all co-crystals and are likely to occur also during the viral polypeptide cleavage process as suggested from docking of the Mpro cleavage recognition sequence. We screened in silico a library of 6900 FDA-approved drugs (ChEMBL) and filtered using these key interactions and selected 29 non-covalent compounds predicted to bind to the protease. Additional screen, using DOCKovalent was carried out on DrugBank library (11,414 experimental and approved drugs) and resulted in 6 covalent compounds. The selected compounds from both screens were tested in vitro by a protease activity inhibition assay. Two compounds showed activity at the 50 µM concentration range. Our analysis and findings can facilitate and focus the development of highly potent inhibitors against SARS-CoV-2 infection.
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Antivirais/farmacologia , Tratamento Farmacológico da COVID-19 , Proteases 3C de Coronavírus/antagonistas & inibidores , Avaliação Pré-Clínica de Medicamentos , Inibidores de Proteases/farmacologia , Sequência de Aminoácidos , Domínio Catalítico/efeitos dos fármacos , Proteases 3C de Coronavírus/metabolismo , Desenho de Fármacos , Descoberta de Drogas , Humanos , Modelos Moleculares , Simulação de Acoplamento Molecular , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/efeitos dos fármacos , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/enzimologia , SARS-CoV-2/efeitos dos fármacos , SARS-CoV-2/enzimologia , Proteínas não Estruturais Virais/antagonistas & inibidores , Proteínas não Estruturais Virais/metabolismoRESUMO
Public Understanding of Science is an interdisciplinary journal serving the scholarly community and practitioners. This article reports an analysis of the readability and jargon in articles published in Public Understanding of Science throughout its almost three decades of existence to examine trends in accessibility to diverse audiences. The accessibility of Public Understanding of Science articles published in 1999/2000 (47), 2009 (49) and 2019 (65) was assessed in terms of readability and use of jargon. Readability decreased and use of jargon increased between 1999 and 2000 and the two following decades for empirical and non-empirical papers, and all parts including the abstracts. An analysis of rare words shows that most are not part of the general academic vocabulary or disciplinary jargon, but rather words that appeared only in one article. Public Understanding of Science has moved away from everyday language. This does not mean it is incomprehensible to its scholarly readership, but may have consequences to other audiences such as practitioners.
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Comunicação , Vocabulário , Compreensão , IdiomaRESUMO
New semiconducting metastable cubic phases have been recently discovered in the tin monosulfide and monoselenide systems. Surface energy calculations and experimental studies indicate that this cubic π-phase is stabilized by specific ligand adsorption on the surface. In this work, it is shown experimentally that the synthesis carried out using mixtures of oleylamine and oleylammonium chloride (OACl) surfactants results in the cubic phase, transforming the growth from orthorhombic to cubic nanoparticles with increasing OACl concentration up to a limiting point. Complementary ab initio calculations find that adsorbed ligands lower the surface energies for both the cubic phase and the orthorhombic phase, relative to the pristine surfaces. The decrease in the surface energy increases with ligand coverage. Stronger binding energies to the cubic phase suggest a higher coverage, and therefore preferential stabilization of this phase. Upon further increasing the coverage, the surface energy becomes negative, effectively destabilizing the particles in agreement with experimental observations. Bonding analysis shows that Cl bonds to Sn and replaces missing Sn-S bonds at the surface of the cubic structure. In the competing orthorhombic layered phase, Cl also bonds to a Sn atom but at the expense of one of the Sn-S bonds of this Sn atom. This observation can explain the trends of the surface energies. This combined experimental and computational analysis sheds light on the stabilization processes of these nano-materials and indicates the path to improve synthetic routes.
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Despite the fact that protein chemistry occurs in solution, studying the structure of desolvated proteins in mass spectrometry vacuum conditions allows one to study biological molecules in complete isolation. The electrospray ionization process results in charged protein conformers for which the charge locations distribution and the corresponding structure are not known. In this paper, we explore the influence of different charge distributions on the structure of conformers of ubiquitin 6+ in the vacuum conditions of mass spectrometry. Using the Tinker implementation of the AMBER99FF force field, the atomistic lowest-energy structures for those charge distributions were calculated by the DEEPSAM algorithm. Differences among the calculated structures are analyzed and discussed in terms of the relation to experimentally observable ion mobility mass spectrometry cross sections. They also are compared to the neutral ubiquitin's native structure and to the nearly linear structure of the ubiquitin 13+ ion. In general, different charge distributions lead to substantially different structures and ion mobility cross sections. In this study, however, it was found that this is not always the case. Our conclusion is that measurements of ion mobility cross sections cannot be used to help determine a unique charge distribution because different charge distributions lead to structures that approximately agree in terms of experimental cross sections.
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Eletroquímica , Ubiquitinas/química , Conformação Proteica , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
Cubic π-phase monochalcogenides (MX, M = Sn, Ge; X = S, Se) are an emerging new class of materials that has recently been discovered. Here, their thermodynamic stability, progress in synthetic routes, properties, and prospective applications are reviewed. The thermodynamic stability is demonstrated through density functional theory total energy and phonon spectra calculations, which show that the π-phase polytype is stable across the monochalcogenide family. To date, only π-phase tin monochalcogenides have been observed experimentally while π-phase Ge-monochalcogenides are predicted to be stable but are yet to be experimentally realized. Various synthetic preparation protocols of π-SnS and π-SnSe are described, focusing on surfactant-assisted nanoparticle synthesis and chemical deposition of thin films from aqueous-bath compositions. These techniques provide materials with different surface energies, which are likely to play a major role in stabilizing the π-phase in nanoscale materials. The properties of this newly discovered family of semiconducting materials are discussed in comparison with their conventional orthorhombic polymorphs. These could benefit a number of photovoltaic and optoelectronic applications since, apart from being cubic, they also possess characteristic advantages, such as moderately low toxicity and natural abundance.
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Finding optimal markers for microorganisms important in the medical, agricultural, environmental or ecological fields is of great importance. Thousands of complete microbial genomes now available allow us, for the first time, to exhaustively identify marker proteins for groups of microbial organisms. In this work, we model the biological task as the well-known mathematical "hitting set" problem, solving it based on both greedy and randomized approximation algorithms. We identify unique markers for 17 phenotypic and taxonomic microbial groups, including proteins related to the nitrite reductase enzyme as markers for the non-anammox nitrifying bacteria group, and two transcription regulation proteins, nusG and yhiF, as markers for the Archaea and Escherichia/Shigella taxonomic groups, respectively. Additionally, we identify marker proteins for three subtypes of pathogenic E. coli, which previously had no known optimal markers. Practically, depending on the completeness of the database this algorithm can be used for identification of marker genes for any microbial group, these marker genes may be prime candidates for the understanding of the genetic basis of the group's phenotype or to help discover novel functions which are uniquely shared among a group of microbes. We show that our method is both theoretically and practically efficient, while establishing an upper bound on its time complexity and approximation ratio; thus, it promises to remain efficient and permit the identification of marker proteins that are specific to phenotypic or taxonomic groups, even as more and more bacterial genomes are being sequenced.
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Archaea/classificação , Archaea/genética , Escherichia/classificação , Escherichia/genética , Marcadores Genéticos/genética , Shigella/classificação , Shigella/genética , Algoritmos , Automação , FenótipoRESUMO
This study examined to what extent Nobel Prize announcements and awards trigger global and local searches or "teachable moments" related to the laureates and their discoveries. We examined the longitudinal trends in Google searches for the names and discoveries of Nobel laureates from 2012 to 2017. The findings show that Nobel Prize events clearly trigger more searches for laureates, but also for their respective discoveries. We suggest that fascination with the Nobel prize creates a teachable moment not only for the underlying science, but also about the nature of science. Locality also emerged as playing a significant role in intensifying interest.
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In the present study, the dynamic process of group formation in eight unfamiliar rats was followed in order to reveal how the group becomes oriented together in time and space, in light of the complexity that accompanies grouping. The focus was on who, where, and when joined together. We found that rats preferred to be in companionship over remaining alone, with all the rats gradually shifting to share the same location as a resting place. Group formation can be viewed as a tri-phasic process, with some rats gradually becoming more social than others, and thus playing a key role in group formation. Starting with seemingly independent traveling, the rats gradually converged to share the same location as a terminal (home base) for roundtrips in the arena. Because such a terminal is considered as the organizer of an individual's spatial behavior, the shared home-base location may be viewed as the organizer of spatial behavior of the entire group. Despite huddling together, the rats continued to travel alone or in duos throughout the 3 h of testing. We suggest that resting together and traveling alone or in duos enabled the maintenance of communal relationship while reducing the complexity involved in traveling in relatively large groups. Taken together, the present results demonstrate the dynamic process during which unfamiliar rats shift from independent to group spatial behavior.
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Comportamento Exploratório , Comportamento Social , Comportamento Espacial , Animais , RatosRESUMO
OBJECTIVES: Intraoperative hairline longitudinal fractures were recently reported in association with distal radius volar plating. Our aim was to further analyze this newly described complication. METHODS: A retrospective radiographic and chart review was performed on 225 patients who underwent distal radius plating between June 2013 and June 2015. The Acu-Loc/Acu-Loc2© plating system (Acumed, Hillsboro, OR, USA) was used in 208 cases, and the VariAx© plating system (Stryker, Kalamazoo, MI, USA) was used in 17 cases. Three independent reviewers performed a blind evaluation of all relevant radiographs for the occurrence of longitudinal fractures around the plate, and validity was considered only when there was agreement among all three of them. RESULTS: Hairline longitudinal fractures were identified in 57 cases (25%), 55 with the Acu-Loc/Acu-Loc2© system and 2 with the VariAx© system. All fractures occurred with volar plating. Fracture occurrence was associated with age over 59 years, female gender, extra-articular fractures, and the use of Hexalobe screws (Acu-Loc/Acu-Loc2© system). CONCLUSIONS: We believe that the source of fracture occurrence lies within the screw design and that better screw design and possibly tapping in patients at risk may reduce the occurrence of intraoperative hairline longitudinal fractures. Further clinical and biomechanical research is needed to better understand this newly reported complication.
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Placas Ósseas/efeitos adversos , Fixação Interna de Fraturas/efeitos adversos , Fixação Interna de Fraturas/instrumentação , Complicações Intraoperatórias/diagnóstico por imagem , Complicações Intraoperatórias/etiologia , Fraturas do Rádio/etiologia , Fraturas do Rádio/cirurgia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Fluoroscopia , Humanos , Masculino , Pessoa de Meia-Idade , Fraturas do Rádio/diagnóstico por imagem , Reoperação , Estudos Retrospectivos , Fatores de Risco , Fatores Sexuais , Resultado do TratamentoRESUMO
Scientists are required to communicate science and research not only to other experts in the field, but also to scientists and experts from other fields, as well as to the public and policymakers. One fundamental suggestion when communicating with non-experts is to avoid professional jargon. However, because they are trained to speak with highly specialized language, avoiding jargon is difficult for scientists, and there is no standard to guide scientists in adjusting their messages. In this research project, we present the development and validation of the data produced by an up-to-date, scientist-friendly program for identifying jargon in popular written texts, based on a corpus of over 90 million words published in the BBC site during the years 2012-2015. The validation of results by the jargon identifier, the De-jargonizer, involved three mini studies: (1) comparison and correlation with existing frequency word lists in the literature; (2) a comparison with previous research on spoken language jargon use in TED transcripts of non-science lectures, TED transcripts of science lectures and transcripts of academic science lectures; and (3) a test of 5,000 pairs of published research abstracts and lay reader summaries describing the same article from the journals PLOS Computational Biology and PLOS Genetics. Validation procedures showed that the data classification of the De-jargonizer significantly correlates with existing frequency word lists, replicates similar jargon differences in previous studies on scientific versus general lectures, and identifies significant differences in jargon use between abstracts and lay summaries. As expected, more jargon was found in the academic abstracts than lay summaries; however, the percentage of jargon in the lay summaries exceeded the amount recommended for the public to understand the text. Thus, the De-jargonizer can help scientists identify problematic jargon when communicating science to non-experts, and be implemented by science communication instructors when evaluating the effectiveness and jargon use of participants in science communication workshops and programs.
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Comunicação , Disseminação de Informação/métodos , Escrita Médica , Vocabulário , Compreensão , Humanos , Ciência/métodosRESUMO
Spatial organization is an extensively studied field, in which most of the research has been on how the physical environment is perceived and conceived. There is a consensus that physical attributes such as environment geometry and landmarks are key factors in shaping spatial cognition. Nevertheless, the numerous studies of spatial behavior have usually been carried out on individuals, thereby overlooking the possible impact of the social environment. In the present study, rats were exposed to an unfamiliar open-field, first alone and then in tetrads of unfamiliar individuals, in order to monitor and analyze when and how their individual spatial behavior converged to a group spatial behavior. We found that the unfamiliar rats spent most of their time in companionship, first with preferred partners and ultimately as a quartet. Specifically, group formation was dynamic and gradual, with the rats first forming duos, then trios, and ultimately a quartet. Trios and quartets mostly huddled in the same specific corner that became a shared home base, from which they took solo or duo roundtrips to the arena. The present study unveils how, by means of gradual interactions among self, place, and conspecifics, four unfamiliar rats organized together their social spatial behavior.
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Comportamento Social , Comportamento Espacial , Animais , Cognição , Masculino , Ratos Sprague-DawleyRESUMO
In response to the news coverage of scientific events and to science education, people increasingly go online to get more information. This study investigates how patterns of science and technology information-seeking on Google and Wikipedia change over time, in ways that differ between "ad hoc" terms that correspond to news coverage and "cyclic" terms that correspond to the academic period. Findings show that the science and technology activity in Google and Wikipedia was significantly associated with ad hoc and cyclic patterns. While the peak activity in Google and Wikipedia largely overlapped for ad hoc terms, it mismatched for cyclic terms. The findings indicate the importance of external cues such as news media and education, and also of the online engagement process, and particularly the crucial but different role played by Google and Wikipedia in gaining science and technology knowledge. Educators and policy makers could benefit from taking into account those different patterns.
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Enciclopédias como Assunto , Comportamento de Busca de Informação , Internet , Ciência , Ferramenta de Busca , Participação da Comunidade , HumanosRESUMO
Blood pressure (BP) variability (BPV) contributes to target organ damage independent of BP. The authors examined the effect of a 1-year multidisciplinary intervention on BPV in patients with the metabolic syndrome (MetS) as defined by criteria from the Third Report of the Adult Treatment Panel. Forty-four nondiabetic patients underwent clinical and biochemical profiling, 24-hour ambulatory BP monitoring (ABPM), body composition, carotid intima-media thickness, and carotid-femoral pulse wave velocity (PWV). The intervention targeted all MetS components. BPV was assessed by the standard deviation of daytime systolic BP derived from ABPM. Patients with low and high BPV (lower or higher than the median daytime standard deviation of 11.6 mm Hg) did not differ in regards to systolic and diastolic BP, age, fasting glucose, glycated hemoglobin, and body mass index, but the high-variability group had higher values of low-density lipoprotein and leg fat. The 1-year intervention resulted in weight reduction but not BP-lowering. BPV declined in the high-variability group in association with lowering of PWV, C-reactive protein, glycated hemoglobin, alanine aminotransferase, asymmetric dimethylarginine, and increased high-density lipoprotein cholesterol. A multidisciplinary intervention independent of BP-lowering normalized BPV, lowered PWV, and enhanced metabolic control.
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Monitorização Ambulatorial da Pressão Arterial/métodos , Pressão Sanguínea/fisiologia , Síndrome Metabólica/fisiopatologia , Síndrome Metabólica/terapia , Espessura Intima-Media Carotídea , Dieta Mediterrânea , Terapia por Exercício , Feminino , Humanos , Hipertensão/dietoterapia , Hipertensão/fisiopatologia , Hipertensão/terapia , Masculino , Síndrome Metabólica/dietoterapia , Pessoa de Meia-Idade , Análise de Onda de Pulso/métodosRESUMO
Predatory bacteria seek and consume other live bacteria. Although belonging to taxonomically diverse groups, relatively few bacterial predator species are known. Consequently, it is difficult to assess the impact of predation within the bacterial realm. As no genetic signatures distinguishing them from non-predatory bacteria are known, genomic resources cannot be exploited to uncover novel predators. In order to identify genes specific to predatory bacteria, we developed a bioinformatic tool called DiffGene. This tool automatically identifies marker genes that are specific to phenotypic or taxonomic groups, by mapping the complete gene content of all available fully-sequenced genomes for the presence/absence of each gene in each genome. A putative 'predator region' of ~60 amino acids in the tryptophan 2,3-dioxygenase (TDO) protein was found to probably be a predator-specific marker. This region is found in all known obligate predator and a few facultative predator genomes, and is absent from most facultative predators and all non-predatory bacteria. We designed PCR primers that uniquely amplify a ~180bp-long sequence within the predators' TDO gene, and validated them in monocultures as well as in metagenetic analysis of environmental wastewater samples. This marker, in addition to its usage in predator identification and phylogenetics, may finally permit reliable enumeration and cataloguing of predatory bacteria from environmental samples, as well as uncovering novel predators.