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A 40-year old woman from Eritrea was admitted due to worsening renal function of unknown origin. The basic nephrologic workup provided no further information. Renal biopsy was performed and revealed acute interstitial nephritis (AIN) while no offending medication could be identified. Further investigations showed a recurrence of the urogenitary tuberculosis that had already been in 2015. The finding of AIN in the absence of a typical medical history should raise suspicion of infection-related forms or AIN associated with systemic diseases.
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Nefrite Intersticial , Adulto , Feminino , Humanos , Rim/fisiologia , Nefrite Intersticial/diagnósticoRESUMO
A low-cost scheme of high-speed asynchronous optical sampling based on Yb:KYW oscillators is reported. Two GHz diode-pumped oscillators with a slight pulse repetition rate offset serve as pump and probe source, respectively. The temporal resolution of this system is limited to 500 fs mainly by the pulse duration of the oscillators and also by relative timing jitter between the oscillators. A near-shot-noise noise floor around 10-6 (∆R/R) is obtained within a data acquisition time of a few seconds. The performance of the system is demonstrated by measurements of coherent acoustic phonons in a semiconductor sample that resembles a semiconductor saturable absorber mirror or an optically pumped semiconductor chip.
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INTRODUCTION: Exercise can provide numerous benefits to haemophilia patients, including bleeding reduction in muscles and joints. AIM: This systematic review (SR) aims to evaluate the effects of physical exercise on pain and the musculoskeletal function of patients with hemophilia. METHODS: Literature searches of Pubmed, Web of Science, PEDro, Cochrane, Clinical Trials SciELO and Lilacs were performed. The risks of bias were measured using the JADAD scale. RESULTS: Nine controlled clinical trials were included in the SR. CONCLUSION: Physical exercise can promote a reduction in the perception of pain and can increase ROM and muscle strength in haemophilia patients. Future RCTs with greater methodological rigor that focus on the parameters used to prescribe exercises are necessary.
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Terapia por Exercício , Exercício Físico/fisiologia , Hemofilia A/terapia , Força Muscular/fisiologia , Dor/prevenção & controle , Ensaios Clínicos como Assunto , Humanos , Qualidade de VidaRESUMO
We present a high-speed asynchronous optical sampling system, based on two different Kerr-lens mode-locked lasers with a GHz repetition rate: An Yb:KYW oscillator and a Ti:sapphire oscillator are synchronized in a master-slave configuration at a repetition rate offset of a few kHz. This system enables two-colour pump-probe measurements with resulting noise floors below 10â»6 at a data aquisition time of 5 seconds. The measured temporal resolution within the 1 ns time window is below 350 fs, including a timing jitter of less than 50 fs. The system is applied to investigate zone-folded coherent acoustic phonons in two different semiconductor superlattices in transmission geometry at a probe wavelength far below the bandgap of the superlattice constituents. The lifetime of the phonon modes with a zero wave vector and frequencies in the range from 100 GHz to 500 GHz are measured at room temperature and compared with previous work.
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PURPOSE: Pressure ulcers are localized injuries to the skin or underlying tissues over a bony prominence, as a result of pressure, or pressure in combination with shear. Ultrasound imaging techniques are widely applied to detect and to investigate pressure ulcer pathogenesis and healing, but due to missing structural alterations, very early signs of tissue alterations are not detectable. Ultrasound elastography was proposed as a new method to measure very early signs of pressure ulcer development but this was not investigated in humans so far. The aim of this study was to investigate for the first time whether US elastography is able to measure potential changes in dermal and subcutaneous tissue stiffness during prolonged loading. MATERIALS AND METHODS: An exploratory study including nine healthy volunteers (mean age 70.1 (SD 4.8) years) was conducted. Study participants were requested to follow a standardized lying protocol, consisting of two loading phases of 90 and 150 min in supine position on a standard hospital mattress. Three pressure ulcer predilection sites (lateral heel over the calcaneus, sacral, and upper back area) were measured using B-mode and elastographic ultrasound system at baseline - immediately, after 90 min, and after 150 min loading. RESULTS: Mean baseline shear wave velocities were highest in the heel skin (2.7 m/s) and lowest in the upper back skin (1.9 m/s) indicating that heel skin was stiffest. Also the subcutaneous soft tissue stiffness was highest for the heel (2.7 m/s) and lowest for the upper back region (1.3 m/s). After 90 and 150 min loading there was a mean stiffness increase of the skin layers and a pronounced stiffness decrease of subcutaneous heel and sacral tissues. CONCLUSIONS: Continuous loading of skin and underlying subcutaneous soft tissues leads to dynamic changes of tissue stiffness which are considered to play key roles in pressure ulcer development. Superficial skin and deep tissues seem to react differently. Elastography is able to quantify the dynamic of skin and subcutaneous soft tissue stiffness changes non-invasively in vivo. Shear wave velocity might serve as a new parameter for quantifying pressure ulcer damage risk in superficial and deeper tissues prone to pressure ulcer development.
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Técnicas de Imagem por Elasticidade , Úlcera por Pressão/diagnóstico por imagem , Pele/diagnóstico por imagem , Tela Subcutânea/diagnóstico por imagem , Idoso , Diagnóstico Precoce , Feminino , Calcanhar/diagnóstico por imagem , Calcanhar/fisiopatologia , Humanos , Úlcera por Pressão/prevenção & controle , Região Sacrococcígea/diagnóstico por imagem , Região Sacrococcígea/fisiopatologia , Pele/fisiopatologia , Tela Subcutânea/fisiopatologia , Fatores de TempoRESUMO
BACKGROUND: There is still a problematic situation in Germany for older migrants, who can be characterized by poverty, lack of knowledge of the healthcare system, generation conflicts and social exclusion. AIM: The objective of this article is the analysis of the chances for social participation of older migrants from two perspectives. MATERIAL AND METHODS: This qualitative study is based on an interdisciplinary research project sponsored by the German Federal Ministry of Education and Research entitled "Cultures of social participation in local communities" (KUSTIS) from the promotion program "Social innovations for quality of life in old age " (SILQUA) and presents selected results from two subprojects. The investigation explored the possibilities for social participation by older migrants in two suburbs of Bremen in Germany, Gröpelingen and Vahr, which have higher than average migrant Turkish and Russian populations. The results of the 3-year study are presented. The first subproject looked at how 40 migrants aged 60 years and over perceived the support from migrant low threshold services and focused on their wishes and needs using a qualitative content analysis. The second subproject investigated the voluntary engagement for older migrants in an intercultural context through considering the views of volunteers who worked with older migrants (28 interviews and 4 focus groups). RESULTS AND CONCLUSION: Both subprojects complement each other to provide an integrated view of low threshold services for older migrants. The analysis shows the significance of migrant organizations for social participation, the heterogeneity of life circumstances, the motivation of engagement and the need for social acknowledgement.
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Envelhecimento/psicologia , Serviços de Saúde Comunitária , Letramento em Saúde , Isolamento Social/psicologia , Participação Social/psicologia , Migrantes/psicologia , Idoso , Idoso de 80 Anos ou mais , Atitude Frente a Saúde , Feminino , Alemanha , Humanos , Masculino , VoliçãoRESUMO
Substantial evidence links alcohol drinking and serotonin (5-HT) functioning in animals. Lowered central 5-HT neurotransmission has been found in a subgroup of alcoholics, possibly those with more aggressive, assaultive tendencies. Several rodent studies have also suggested that intact 5-HT systems are important determinants of sensitivity and/or tolerance to ethanol-induced ataxia and hypothermia. Null mutant mice lacking the 5-HT1B receptor gene (5-HT1B-/-) have been developed that display enhanced aggression and altered 5-HT release in slice preparations from some, but not all, brain areas. We characterized these mice for sensitivity to several effects of ethanol. Mutant mice drank twice as much ethanol as wild-type mice, and voluntarily ingested solutions containing up to 20% ethanol in water. Their intake of food and water, and of sucrose, saccharin and quinine solutions, was normal. Mutants were less sensitive than wild-types on a test of ethanol-induced ataxia and, with repeated drug administration, tended to develop tolerance more slowly. In tests of ethanol withdrawal and metabolism, mutants and wild-type mice showed equivalent responses. Our results suggest that the 5-HT1B receptor participates in the regulation of ethanol drinking, and demonstrate that serotonergic manipulations lead to reduced responsiveness to certain ataxic effects of ethanol without affecting dependence.
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Consumo de Bebidas Alcoólicas , Receptores de Serotonina/fisiologia , Consumo de Bebidas Alcoólicas/efeitos adversos , Animais , Ataxia/induzido quimicamente , Ataxia/fisiopatologia , Ingestão de Alimentos , Etanol/efeitos adversos , Etanol/farmacologia , Humanos , Camundongos , Camundongos Knockout , Receptor 5-HT1B de Serotonina , Receptores de Serotonina/genética , Síndrome de Abstinência a Substâncias/fisiopatologiaRESUMO
BACKGROUND: Cannabis varies considerably in levels of its two major constituent cannabinoids - (delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Recently, we found evidence that those who smoked cannabis containing detectable levels of CBD had fewer psychotic-like symptoms than those whose cannabis had no CBD. The present study aimed, first, to replicate those findings and, second, to determine whether protective effects of CBD may extend to other harms of cannabis, such as memory impairment and reduced psychological well-being. METHOD: A total of 120 current cannabis smokers, 66 daily users and 54 recreational users were classified into groups according to whether analysis of their hair revealed the presence or absence of CBD and high versus low levels of THC. All were assessed on measures of psychosis-like symptoms, memory (prose recall; source memory) and depression/anxiety. RESULTS: Lower psychosis-like symptoms were found in those whose hair had CBD compared with those without. However, this was seen only in recreational users, who had higher levels of THC in their hair. Higher THC levels in hair were associated with increased depression and anxiety. Prose recall and source memory were poorer in daily users with high THC levels in hair while recognition memory was better in individuals with CBD present in hair. CONCLUSIONS: CBD attenuates the psychotic-like effects of cannabis over time in recreational users. Higher THC negatively impacts on memory and psychological well-being. These findings raise concerns for the harms stemming from use of varieties such as 'skunk' (sensimillia), which lack any CBD but currently dominate the supply of cannabis in many countries.
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Canabidiol/farmacologia , Transtornos Cognitivos/prevenção & controle , Depressão/induzido quimicamente , Dronabinol/efeitos adversos , Drogas Ilícitas/farmacologia , Fumar Maconha , Memória/efeitos dos fármacos , Transtorno da Personalidade Esquizotípica/prevenção & controle , Adolescente , Adulto , Ansiedade/induzido quimicamente , Canabidiol/análise , Canabidiol/uso terapêutico , Transtornos Cognitivos/induzido quimicamente , Dronabinol/análise , Dronabinol/farmacologia , Feminino , Cabelo/química , Humanos , Drogas Ilícitas/efeitos adversos , Masculino , Fumar Maconha/efeitos adversos , Psicoses Induzidas por Substâncias/etiologia , Psicoses Induzidas por Substâncias/prevenção & controle , Transtorno da Personalidade Esquizotípica/induzido quimicamente , Adulto JovemRESUMO
BACKGROUND: Patients with metabolic syndrome (MS) and type 2 diabetes (T2DM) show increased risk for coronary artery disease. Lipoprotein metabolism is characterized by elevated triglycerides (TG), low high-density lipoprotein cholesterol (HDL-C) and predominance of atherogenic small, dense low-density lipoprotein (sdLDL), while low-density lipoprotein (LDL) cholesterol is only slightly elevated. METHODS: Multicentre, randomized, open-label cross-over study investigating the effect of combination of fluvastatin/fenofibrate (80/200 mg) (F&F) on LDL-subfractions compared with combination of simvastatin/ezetimibe (20/10 mg) (S&E) in patients with MS/T2DM. RESULTS: Seventy-five patients were randomized, 69 completed the study and LDL-subfractions of 56 patients were analysed. Thirty-eight out of 56 patients (68%) showed a profile dominated by sdLDL. In these, TG and total cholesterol (TC) were elevated compared with non-sdLDL patients. In all patients, reduction of TC and LDL cholesterol (LDL-C) by S&E was stronger than by F&F. The increase of HDL-C was stronger with S&E in the non-sdLDL group, whereas in the sdLDL group, there was no difference between treatments. In non-sdLDL patients, there was no effect on TG or LDL-radius. However, in the sdLDL group, F&F was more effective in reducing TG and increased LDL radius, whereas S&E reduced LDL radius even further. CONCLUSIONS: S&E is more efficient in reducing TC and LDL-C. This is also true for HDL-C increase in non-sdLDL patients. However, in patients with sdLDL, F&F was more efficient in reducing TG and increasing LDL radius.
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LDL-Colesterol/efeitos dos fármacos , Doença da Artéria Coronariana/tratamento farmacológico , Síndrome Metabólica/tratamento farmacológico , Anticolesterolemiantes/administração & dosagem , Azetidinas/administração & dosagem , Doença da Artéria Coronariana/prevenção & controle , Esquema de Medicação , Quimioterapia Combinada , Ezetimiba , Ácidos Graxos Monoinsaturados/administração & dosagem , Feminino , Fenofibrato/administração & dosagem , Fluvastatina , Humanos , Indóis/administração & dosagem , Masculino , Pessoa de Meia-Idade , Sinvastatina/administração & dosagem , Resultado do TratamentoRESUMO
This paper presents a new modelling approach to describe and explain the temporal variation of oil thickness in well due to groundwater table fluctuations. This new model, which intends to be simple and easy to implement, was compared to field data obtained by continuous measurements of vertical LNAPL position in wells. Two scenarios have been studied: a pumping well where the oil layer is unconfined, and one where the oil layer is present in a confined porous media. This study shows that the time-depend fluctuation of the oil thickness observed in the wells could not be reproduced only with the differences between the residual oil saturations (Sorw and Sora) as suggested by Kemblowski and Chiang (1990). It should consider the transient mass exchange between the well and the porous media. Also, the proposed model shows that making the assumption of equilibrium conditions as suggested by Lenhard et al. (2017) for calculating the volume exchanges between the wells and its surrounding introduced errors. Considering transient transfers of oil better reflects the field observations. This observation is a key outcome for improving field data interpretation (e.g.: bail-down test data) and the remedial approach at site polluted by mineral oils.
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Água Subterrânea , Porosidade , Poços de ÁguaRESUMO
In the late 1970s, on the basis of rRNA phylogeny, Archaea (archaebacteria) was identified as a distinct domain of life besides Bacteria (eubacteria) and Eucarya. Though forming a separate domain, Archaea display an enormous diversity of lifestyles and metabolic capabilities. Many archaeal species are adapted to extreme environments with respect to salinity, temperatures around the boiling point of water, and/or extremely alkaline or acidic pH. This has posed the challenge of studying the molecular and mechanistic bases on which these organisms can cope with such adverse conditions. This review considers our cumulative knowledge on archaeal mechanisms of primary energy conservation, in relationship to those of bacteria and eucarya. Although the universal principle of chemiosmotic energy conservation also holds for Archaea, distinct features have been discovered with respect to novel ion-transducing, membrane-residing protein complexes and the use of novel cofactors in bioenergetics of methanogenesis. From aerobically respiring Archaea, unusual electron-transporting supercomplexes could be isolated and functionally resolved, and a proposal on the organization of archaeal electron transport chains has been presented. The unique functions of archaeal rhodopsins as sensory systems and as proton or chloride pumps have been elucidated on the basis of recent structural information on the atomic scale. Whereas components of methanogenesis and of phototrophic energy transduction in halobacteria appear to be unique to Archaea, respiratory complexes and the ATP synthase exhibit some chimeric features with respect to their evolutionary origin. Nevertheless, archaeal ATP synthases are to be considered distinct members of this family of secondary energy transducers. A major challenge to future investigations is the development of archaeal genetic transformation systems, in order to gain access to the regulation of bioenergetic systems and to overproducers of archaeal membrane proteins as a prerequisite for their crystallization.
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Archaea/metabolismo , Metabolismo Energético , Aerobiose , Transporte de Elétrons , Euryarchaeota/metabolismo , Luz , PrótonsRESUMO
The cognitive benefits of acute flavonoid interventions have been well documented, however, research to date has found that, depending on developmental stage, these benefits manifest themselves in different cognitive domains. It is argued that the lack of global cognitive effects following flavonoid intervention may be a result of insufficient task sensitivity for those domains where no benefits are found. In children, executive function is a cognitive domain which has shown little apparent benefit following flavonoid intervention. Here, we describe a Modified Attention Network Task (MANT) designed to vary levels of cognitive demand across trials in order to investigate whether flavonoid related benefits can be shown for executive function when task sensitivity is carefully manipulated. Twenty-one children were recruited to a double blind cross-over study consuming 30 g freeze dried blueberry powder (WBB) or placebo before being tested at 3 hours. Performance in the WBB condition was found to be significantly faster in comparison to placebo particularly on more cognitively demanding incongruent and high load trials. Trials in which a visual cue alerted participants to the imminent appearance of the target also showed better performance following WBB administration. We conclude that WBB administration can enhance executive function during demanding elements of a task, but that the complexity and demand of the task as a whole may be equally important to performance.
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Mirtilos Azuis (Planta)/metabolismo , Cognição , Função Executiva , Atenção , Mirtilos Azuis (Planta)/química , Criança , Estudos Cross-Over , Suplementos Nutricionais/análise , Método Duplo-Cego , Feminino , Flavonoides/análise , Flavonoides/metabolismo , Frutas/química , Frutas/metabolismo , Humanos , MasculinoRESUMO
BACKGROUND: Protein targeting to the endoplasmic reticulum in eukaryotes and to the cell membrane in prokaryotes is mediated by the signal recognition particle (SRP) and its receptor (SR). Both contain conserved GTPase domains in the signal-peptide-binding proteins (SRP54 and Ffh) and the SR proteins (SRalpha and FtsY). These GTPases are involved in the regulation of protein targeting. Most studies so far have focussed on the SRP machinery of mammals and bacteria, leaving the SRP system of archaea less well understood. RESULTS: We report the crystal structure of the conserved GTPase (NG-Ffh) from the thermophilic archaeon Acidianus ambivalens at 2.0 A resolution and of the Thr112-->Ala mutant, which is inactive in GTP hydrolysis. This is the first structure of an SRP component from an archaeon and allows for a detailed comparison with related structures from Escherichia coli and thermophilic bacteria. In particular, differences in the conserved consensus regions for nucleotide binding and the subdomain interfaces are observed, which provide information about the regulation of the GTPase. These interactions allow us to propose a common signalling mechanism for the SRP-SR system. CONCLUSIONS: The overall structure of SRP-GTPases is well conserved between bacteria and archaea, which indicates strong similarities in the regulation of the SRP-targeting pathway. Surprisingly, structure comparisons identified a homodimeric ATP-binding protein as the closest relative. A heterodimer model for the SRP-SR interaction is presented.
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Archaea/enzimologia , Proteínas de Bactérias/química , Proteínas de Escherichia coli , GTP Fosfo-Hidrolases/química , Modelos Moleculares , Proteínas de Saccharomyces cerevisiae , Partícula de Reconhecimento de Sinal/química , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Sequência Conservada , Cristalografia por Raios X , GTP Fosfo-Hidrolases/metabolismo , Dados de Sequência Molecular , Nucleotídeos/metabolismo , Ligação Proteica , Estrutura Terciária de Proteína , Homologia de Sequência de Aminoácidos , Partícula de Reconhecimento de Sinal/metabolismo , Transdução de SinaisRESUMO
Phorbol ester-induced promotion of initiated NMRI mouse skin keratinocytes to papillomas could be largely prevented when nicotinamide-like inhibitors of poly(ADP-ribose)polymerase (nicotinamide, benzamide, 3-aminobenzamide) were applied simultaneously with 12-O-tetradecanoylphorbol-13-acetate (TPA). A similar suppression of tumor promotion by nicotinamide analogues was demonstrated in clone 41 JB6 epidermal cells which are promotable by TPA to anchorage-independent growth. The antipromotion effect of nicotinamide analogues, however, does not appear to come about by an inhibition of poly(ADP-ribose)polymerase. Acid analogues of nicotinamide, such as benzoic acid or 3-aminobenzoic acid which do not inhibit the polymerase, showed antipromotion activity similar to that of their corresponding amides. It could also be ruled out that these antipromoters mediate their effect on keratinocytes by a cytostatic action, by scavenging the promoter TPA in a chemical reaction, or by inhibiting protein kinase C. In initiated mouse skin, nicotinamide analogues strongly suppressed TPA-induced accumulation of inflammatory cells and vascular permeability, while epidermal hyperplasia was not significantly affected.
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Antineoplásicos , Niacinamida/análogos & derivados , Niacinamida/uso terapêutico , Papiloma/prevenção & controle , Neoplasias Cutâneas/prevenção & controle , Acetato de Tetradecanoilforbol/toxicidade , 9,10-Dimetil-1,2-benzantraceno , Aminobenzoatos/farmacologia , Aminobenzoatos/uso terapêutico , Animais , Benzamidas/farmacologia , Benzamidas/uso terapêutico , Benzoatos/farmacologia , Benzoatos/uso terapêutico , Ácido Benzoico , Divisão Celular/efeitos dos fármacos , Células Clonais , Replicação do DNA/efeitos dos fármacos , Feminino , Queratinócitos/efeitos dos fármacos , Queratinócitos/patologia , Cinética , Camundongos , Camundongos Endogâmicos , Niacinamida/farmacologia , Papiloma/induzido quimicamente , Inibidores de Poli(ADP-Ribose) Polimerases , Pele/efeitos dos fármacos , Pele/patologia , Neoplasias Cutâneas/induzido quimicamente , meta-AminobenzoatosRESUMO
All aerobic organisms use the exergonic reduction of molecular oxygen to water as primary source of metabolic energy. This reaction is catalyzed by membrane residing terminal heme/Cu-oxidases which belong to a superfamily of widely varying structural complexity between mitochondrial and bacterial members of this family. Over the last few years, considerable information from this and other laboratories accumulated also on archaeal respiratory chains and their terminal oxidases. In the following, the molecular and catalytic properties of the latter are discussed and compared to those from bacteria and eucarya under the aspect of their energy conserving capabilities and their phylogenetic relations. The Rieske iron-sulfur proteins being important functional constituents of energy transducing respiratory complexes are included in this study. A number of essential conclusions can be drawn. (1) Like bacteria, archaea can also contain split respiratory chains with parallel expression of separate terminal oxidases. (2) The functional core of all oxidases is the highly conserved topological motif of subunit I consisting of at least 12 membrane spanning helices with the 6 histidine residues of the heme/Cu-binding centers in identical locations. (3) Some archaeal oxidases are organized in unusual supercomplexes with other cytochromes and Rieske [2Fe2S] proteins. These complexes are likely to function as proton pumps, whereas on a structural basis several subunit I equivalents alone are postulated to be unable to pump protons. (4) The genes of two archaeal Rieske proteins have been cloned from Sulfolobus; phylogenetically they are forming a separate archaeal branch and suggest the existence of an evolutionary ancestor preceding the split into the three urkingdoms. (5) Archaeal oxidase complexes may combine features of electron transport systems occurring exclusively as separate respiratory complexes in bacteria and eucarya. (6) As far back as the deepest branches of the phylogentic tree, terminal oxidases reveal a degree of complexity comparable to that found in higher organisms. (7) Sequence analysis suggests a monophyletic origin of terminal oxidases with an early split into two types found in archaea as well as bacteria. This view implies an origin of terminal oxidases prior to oxygenic photosynthesis in contrast to the widely accepted inverse hypothesis.
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Archaea/metabolismo , Proteínas de Bactérias/fisiologia , Complexo III da Cadeia de Transporte de Elétrons , Sequência de Aminoácidos , Grupo dos Citocromos a/fisiologia , Transporte de Elétrons , Complexo IV da Cadeia de Transporte de Elétrons/fisiologia , Humanos , Proteínas Ferro-Enxofre/fisiologia , Dados de Sequência Molecular , Relação Estrutura-AtividadeRESUMO
Archaea are forming one of the three kingdoms defining the universal phylogenetic tree of living organisms. Within itself this kingdom is heterogenous regarding the mechanisms for deriving energy from the environment for support of cellular functions. These comprise fermentative and chemolithotrophic pathways as well as light driven and respiratory energy conservation. Due to their extreme growth conditions access to the molecular machineries of energy transduction in archaea can be experimentally limited. Among the aerobic, extreme thermoacidophilic archaea, the genus Sulfolobus has been studied in greater detail than many others and provides a comprehensive picture of bioenergetics on the level of substrate metabolism, formation and utilization of high energy phosphate bonds, and primary energy conservation in respiratory electron transport. A number of novel metabolic reactions as well as unusual structures of respiratory enzyme complexes have been detected. Since their genomic organization and many other primary structures could be determined, these studies shed light on the evolution of various bioenergetic modules. It is the aim of this comprehensive review to bring the different aspects of Sulfolobus bioenergetics into focus as a representative example of, and point of comparison for closely related, aerobic archaea.
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Metabolismo Energético , Sulfolobus/metabolismo , Adenilato Quinase/química , Sequência de Aminoácidos , Transporte de Elétrons , Dados de Sequência Molecular , Oxirredução , Fosfatos/metabolismoRESUMO
The nucleotide sequence of an open reading frame, located upstream of the gene for adenylate kinase, was determined in the thermoacidophile crenarchaeon Sulfolobus acidocaldarius. Data bank searches identified the sequence as a secY homologous gene. The DNA derived protein sequence of total 463 amino acids contains 10 hydrophobic domains. A sequence alignment with other prokaryotic and eukaryotic secY sequences reveals significant homology, but the secY primary sequence of S. acidocaldarius shows only a low degree of similarity with the secY counterparts of the euryarchaea Methanococcus vannielii and Haloarcula marismortui. A transcription analysis indicates, that the secY gene is cotranscribed with the gene coding for adenylate kinase.
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Adenilato Quinase/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Escherichia coli , Genes Bacterianos , Sulfolobus/genética , Sequência de Aminoácidos , Proteínas de Bactérias/biossíntese , Sequência de Bases , DNA Bacteriano/química , DNA Bacteriano/metabolismo , Dados de Sequência Molecular , Fases de Leitura Aberta , Canais de Translocação SEC , Homologia de Sequência de Aminoácidos , Sulfolobus/metabolismoRESUMO
The fluorescence properties of 3'-O-(1-naphthoyl)adenosine di- and triphosphates (termed N-ADP and N-ATP, respectively) were investigated in detail. Of special importance for the use of these analogues as environmental probes is their high quantum yield (0.58 in water) and the polarity dependence of shape and wavelength position of the emission spectrum. Upon binding of N-ADP and N-ATP to mitochondrial F1-ATPase, the fluorescence intensity is markedly decreased, due to polarity changes and 'ground-state' quenching. Using this signal for equilibrium binding studies, three (at least a priori) equivalent nucleotide-binding sites were detected on the enzyme. The perspective intrinsic dissociation constants are as follows: N-ADP/Mg2+ 120 nM; N-ATP/Mg2+ 160 nM; N-ADP/EDTA 560 nM; N-ATP/EDTA 3500 nM. For bound ligand the environment was found to be rather unipolar; the rotational mobility of the fluorophore is restricted, its accessibility for iodide anions (as a quencher) is hindered. These facts show a location of the binding sites quite deeply embedded in the protein. The conformation of the binding domains is strongly dependent on the absence or presence of Mg2+, as can be seen from the relative efficiencies of the singlet-singlet energy transfer from tyrosine residues in the protein to bound naphthoyl moieties. Investigation of the binding kinetics revealed this process as biphasic (in presence of Mg2+). After the first fast step (kon greater than 1 X 10(6) M-1 X s-1), in which the analogue is bound to the enzyme, a slow local conformational rearrangement occurs.
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Difosfato de Adenosina/análogos & derivados , Trifosfato de Adenosina/análogos & derivados , ATPases Translocadoras de Prótons/metabolismo , Difosfato de Adenosina/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Sítios de Ligação , Bovinos , Corantes Fluorescentes , Cinética , Mitocôndrias Cardíacas/enzimologia , Ligação Proteica , Espectrometria de FluorescênciaRESUMO
Archaebacterial plasma membranes contain an ATPase acting in vivo as a delta mu H(+)-driven ATP synthase. While functional features and their general structural design are resembling F-type ATPases, primary sequences of the two large polypeptides from the catalytic part are closely related to V-type ATPases from eucaryotic vacuolar membranes. The chimeric nature of archaebacterial ATPase from Sulfolobus was investigated in terms of nucleotide interactions and related to specific sequence parameters in a comparison to well known F- and V-type ATPases. The study disclosed a general difference of F- and V-type ATPases at one class of the nucleotide binding sites.
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Archaea/enzimologia , ATPases Translocadoras de Prótons/química , Sequência de Aminoácidos , Animais , Sítios de Ligação , Quimera , Dados de Sequência Molecular , Conformação Proteica , ATPases Translocadoras de Prótons/metabolismo , Alinhamento de SequênciaRESUMO
A 1.6 kb genomic DNA fragment derived from the extremely thermoacidophilic archaeon Sulfolobus acidocaldarius (DSM 639) comprises four open reading frames. The sequence contains three genes encoding crenarchaeal ribosomal proteins with apparent molecular masses of 6.3 kDa, 15.2 kDa and 9.9 kDa, which all represent strongly basic properties. These were identified by sequence comparison as RL46, RL31 and RL33. One open reading frame encodes a new polypeptide (22.1 kDa, pI = 7.3) with no homology to known proteins. The latter is transcribed as a common mRNA with RL46 and RL31. This gene cluster immediately precedes another cluster including genes encoding the putative SRP receptor alpha subunit as well as the putative secEp.