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1.
Cell ; 175(4): 947-961.e17, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30401435

RESUMO

Interactions between the gut microbiota, diet, and the host potentially contribute to the development of metabolic diseases. Here, we identify imidazole propionate as a microbially produced histidine-derived metabolite that is present at higher concentrations in subjects with versus without type 2 diabetes. We show that imidazole propionate is produced from histidine in a gut simulator at higher concentrations when using fecal microbiota from subjects with versus without type 2 diabetes and that it impairs glucose tolerance when administered to mice. We further show that imidazole propionate impairs insulin signaling at the level of insulin receptor substrate through the activation of p38γ MAPK, which promotes p62 phosphorylation and, subsequently, activation of mechanistic target of rapamycin complex 1 (mTORC1). We also demonstrate increased activation of p62 and mTORC1 in liver from subjects with type 2 diabetes. Our findings indicate that the microbial metabolite imidazole propionate may contribute to the pathogenesis of type 2 diabetes.


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Microbioma Gastrointestinal , Imidazóis/metabolismo , Insulina/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Transdução de Sinais , Animais , Células Cultivadas , Diabetes Mellitus Tipo 2/microbiologia , Células HEK293 , Histidina/metabolismo , Humanos , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteína Sequestossoma-1/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
2.
J Am Chem Soc ; 146(25): 17318-17324, 2024 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-38869185

RESUMO

Covalent organic frameworks (COFs) containing well-defined redox-active groups have become competitive materials for next-generation batteries. Although high potentials and rate performance can be expected, only a few examples of p-type COFs have been reported for charge storage to date with even fewer examples on the use of COFs in multivalent ion batteries. Herein, we report the synthesis of a p-type highly porous and crystalline azatruxene-based COF and its application as a positive electrode material in Li- and Mg-based batteries. When this material is used in Li-based half cells as a COF/carbon nanotube (CNT) electrode, a discharge potential of 3.9 V is obtained with discharge capacities of up to 70 mAh g-1 at a 2 C rate. In Mg batteries using a tetrakis(hexafluoroisopropyloxy)borate electrolyte, cycling proceeds with an average discharge voltage of 2.9 V. Even at a fast current rate of 5 C, the capacity retention amounts to 84% over 1000 cycles.

3.
Eur J Epidemiol ; 39(1): 35-49, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38165527

RESUMO

Reduced lung function is associated with cardiovascular mortality, but the relationships with atherosclerosis are unclear. The population-based Swedish CArdioPulmonary BioImage study measured lung function, emphysema, coronary CT angiography, coronary calcium, carotid plaques and ankle-brachial index in 29,593 men and women aged 50-64 years. The results were confirmed using 2-sample Mendelian randomization. Lower lung function and emphysema were associated with more atherosclerosis, but these relationships were attenuated after adjustment for cardiovascular risk factors. Lung function was not associated with coronary atherosclerosis in 14,524 never-smokers. No potentially causal effect of lung function on atherosclerosis, or vice versa, was found in the 2-sample Mendelian randomization analysis. Here we show that reduced lung function and atherosclerosis are correlated in the population, but probably not causally related. Assessing lung function in addition to conventional cardiovascular risk factors to gauge risk of subclinical atherosclerosis is probably not meaningful, but low lung function found by chance should alert for atherosclerosis.


Assuntos
Aterosclerose , Doenças das Artérias Carótidas , Doença da Artéria Coronariana , Enfisema , Masculino , Humanos , Feminino , Fatores de Risco , Doenças das Artérias Carótidas/epidemiologia , Aterosclerose/epidemiologia , Doença da Artéria Coronariana/epidemiologia , Pulmão
4.
Scand J Med Sci Sports ; 32(5): 866-880, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35080270

RESUMO

The present study aims to describe accelerometer-assessed physical activity (PA) patterns and fulfillment of PA recommendations in a large sample of middle-aged men and women, and to study differences between subgroups of socio-demographic, socio-economic, and lifestyle-related variables. A total of 27 890 (92.5% of total participants, 52% women, aged 50-64 years) middle-aged men and women with at least four days of valid hip-worn accelerometer data (Actigraph GT3X+, wGT3X+ and wGT3X-BT) from the Swedish CArdioPulmonary bioImage Study, SCAPIS, were included. In total, 54.5% of daily wear time was spent sedentary, 39.1% in low, 5.4% in moderate, and only 0.1% in vigorous PA. Male sex, higher education, low financial strain, born in Sweden, and sedentary/light working situation were related to higher sedentary time, but also higher levels of vigorous PA. High BMI and having multiple chronic diseases associated strongly with higher sedentary time and less time in all three PA intensities. All-year physically active commuters had an overall more active PA pattern. The proportion fulfilling current PA recommendations varied substantially (1.4% to 92.2%) depending on data handling procedures and definition used. Twenty-eight percent was defined as having an "at-risk" behavior, which included both high sedentary time and low vigorous PA. In this large population-based sample, a majority of time was spent sedentary and only a fraction in vigorous PA, with clinically important variations between subgroups. This study provides important reference material and emphasizes the importance of a comprehensive assessment of all aspects of the individual PA pattern in future research and clinical practice.


Assuntos
Exercício Físico , Comportamento Sedentário , Acelerometria , Adulto , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Atividade Motora
5.
Int J Audiol ; 61(12): 1035-1044, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-34851208

RESUMO

OBJECTIVE: Compare the relative efficacy of DesyncraTM and Cognitive Behavioural Therapy (CBT). DESIGN AND STUDY SAMPLE: Sixty-one participants were randomly assigned to receive either DesyncraTM (n = 29) or CBT (n = 32). Randomisation included stratification regarding current hearing aid (HA) use. Depending on group assignment, participants attended approximately 7-12 visits. Tinnitus distress was measured using the Tinnitus Questionnaire (TQ). RESULTS: Mean TQ scores decreased post-baseline from 5-15 points across treatment arms and strata. Model-based findings for the no-HA stratum showed a difference of -2.0 TQ points favouring Desyncra at 24-weeks, with a 90% posterior interval varying from -5.4 points favouring Desyncra to 0.8 TQ points favouring CBT. For the HA stratum, results show a difference of -1.0 TQ points favouring Desyncra, with a 90% posterior interval ranging from -4.7 points favouring Desyncra to 2.9 points favouring CBT. CONCLUSIONS: The difference between Desyncra and CBT on average showed greater improvement with Desyncra in the no-HA stratum by about 2 TQ points. To the extent that the study sample represents a clinical population and recognising the assumptions in the design and analysis, these results suggest Desyncra is just as effective or more so than CBT in reducing tinnitus distress.


Assuntos
Terapia Cognitivo-Comportamental , Auxiliares de Audição , Zumbido , Humanos , Zumbido/terapia , Zumbido/psicologia , Resultado do Tratamento , Terapia Cognitivo-Comportamental/métodos , Inquéritos e Questionários
6.
Am J Occup Ther ; 76(4)2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35709003

RESUMO

IMPORTANCE: Identifying the extent and predictors of burnout among occupational therapy practitioners is important so strategies can be developed to reduce burnout and mitigate associated consequences within the profession. OBJECTIVE: To investigate the prevalence and determinants of burnout reported by U.S. occupational therapy practitioners. DESIGN: Cross-sectional survey. PARTICIPANTS: Occupational therapy practitioners working in a wide range of clinical settings who spent at least 50% of their time in direct patient care and who had been employed continuously for more than 6 mo. OUTCOMES AND MEASURES: The outcome of interest was burnout, which was measured using the Emotional Exhaustion, Depersonalization, and Personal Accomplishment subscales of the Maslach Burnout Inventory-Human Services Survey (MBI-HSS). Predictor variables included sociodemographic and workplace characteristics. The relationship between MBI-HSS subscale scores and predictor variables was jointly estimated using a multivariate multivariable linear regression analysis. RESULTS: One hundred seventy-eight occupational therapy practitioners completed the survey. Higher perceived level of supervisor support, satisfaction with income, and educational attainment were associated with lower MBI-HSS subscale scores (ps = .001, .002, and .005, respectively). CONCLUSIONS AND RELEVANCE: Burnout among occupational therapy practitioners can be conceptualized as an issue of workplace health and safety. Various stakeholder groups can consider potential systematic interventions involving measures to promote positive supervisor support in the workplace and salary negotiation skills for early-stage clinicians. Future research should explore broad interventions to reduce burnout among clinicians. What This Article Adds: We estimated the extent and predictors of burnout among U.S. occupational therapy practitioners. Future research, advocacy, and policy should address structural-level interventions to promote workplace cultures and conditions that can protect the occupational therapy workforce from burnout.


Assuntos
Esgotamento Profissional , Terapia Ocupacional , Esgotamento Profissional/epidemiologia , Esgotamento Profissional/psicologia , Esgotamento Psicológico/psicologia , Estudos Transversais , Humanos , Satisfação no Emprego , Prevalência , Inquéritos e Questionários , Estados Unidos/epidemiologia
7.
Phys Chem Chem Phys ; 23(2): 1616-1626, 2021 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-33410837

RESUMO

The Kamlet-Taft dipolarity/polarizability parameters π* for various ionic liquids were determined using 4-tert-butyl-2-((dicyanomethylene)-5-[4-N,N-diethylamino)-benzylidene]-Δ3-thiazoline and 5-(N,N-dimethylamino)-5'-nitro-2,2'-bithiophene as solvatochromic probes. In contrast to the established π*-probe N,N-diethylnitroaniline, the chromophores presented here show excellent agreement with polarity measurement using the chemical shift of 129Xe. They do not suffer from additional bathochromic UV/vis shifts caused by hydrogen-bonding resulting in too high π*-values for some ionic liquids. In combination with large sets of various ionic liquids, these new chromophores thereby allow for detailed analysis of the physical significance of π* and the comparison to quantum-mechanical methods. We find that π* correlates strongly with the ratio of molar refractivity to molar volume, and thus with the refractive index.

8.
Phys Chem Chem Phys ; 23(47): 26750-26760, 2021 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-34846390

RESUMO

UV/Vis absorption data of (E)-4-(2-[5-{4,4,5,5-tetramethyl-1,3,2-dioxaborolane-2-yl}thiene-2-yl]vinyl)-2-(dicyano-methylene)-3-cyano-5,5-dimethyl-2,5-dihydrofuran (ThTCF) as a solvatochromic probe is applied to examine the anion coordination strength (e.g. of N(CN)2, BF4, PF6, N(Tf)2, CF3COO) as a function of the cation structure of ionic liquids. Several 1-n-alky-3-methylimidazolium- and tetraalkylammonium CH3-NR3+-based ILs with different n-alkyl chain lengths (R = -C4H9, -C6H11, -C8H17, -C10H21) are considered. UV/Vis absorption data of ThTCF show subtle correlations with hydrogen bond accepting (HBA) ability-related measurands such as Kamlet-Taft ß, Freire's EHB, and Laurence ß1 parameter as a function of anion and cation structure. The different influence of the n-alkyl chain length of imidazolium- and tetraalkylammonium-based ILs on the dipolarity and HBA strength is confirmed by comparison with the 14N isotropic hyperfine coupling constants (Aiso) of a positively (CATI) and negatively charged spin probe (TSKCr) of TEMPO-type [(2,2,6,6-tetramethylpiperidin-1-yl)oxyl] and quantum chemically derived dipoles of the cations. The Aiso values correlate with the absorption energy of ThTCF and EHB, but in different ways depending on the anion or charge of the spin probe. In a final discussion of the ß, EHB, and ß1 scales in relation to ThTCF, the importance of the molar concentration N of ionic liquids for the physical significance of the respective parameters is discussed.

9.
Environ Sci Technol ; 54(2): 862-869, 2020 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-31886652

RESUMO

Iron(III) (Fe(III)) photoreduction plays an important role in Fe cycling and Fe(II) bioavailability in the upper ocean. Although well described for water columns, it is currently unknown to what extent light impacts the production of dissolved Fe(II) (Fe2+) in aquatic sediments. We performed high-resolution voltammetric microsensor measurements and demonstrated light-induced Fe2+ release in freshwater sediments from Lake Constance. Fe2+ concentrations increased up to 40 µM in the top 3 mm of the sediment during illumination in the visible range of light (400-700 nm), even in the presence of oxygen (100-280 µM). The Fe2+ release was strongly dependent on the organic matter content of the sediment. A lack of photoreduced Fe2+ was measured in sediments with concentrations of organic carbon <6 mg L-1. The simultaneous presence of sedimentary Fe(III) photoreduction besides microbial and abiotic Fe2+ oxidation by oxygen suggests an active Fe redox cycling in the oxic and photic zone of aquatic sediments. Here, we provide evidence for a relevant contribution of Fe(III) photoreduction to the bio-geochemical Fe redox cycle in aquatic freshwater sediments.


Assuntos
Compostos Férricos , Sedimentos Geológicos , Carbono , Ferro , Lagos , Oxirredução
10.
Environ Sci Technol ; 54(6): 3209-3218, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32064861

RESUMO

Iron (Fe) biogeochemistry in marine sediments is driven by redox transformations creating Fe(II) and Fe(III) gradients. As sediments are physically mixed by wave action or bioturbation, Fe gradients re-establish regularly. In order to identify the response of dissolved Fe(II) (Fe2+) and Fe mineral phases toward mixing processes, we performed voltammetric microsensor measurements, sequential Fe extractions, and Mössbauer spectroscopy of 12 h light-dark cycle incubated marine coastal sediment. Fe2+ decreased during 7 days of undisturbed incubation from approximately 400 to 60 µM. In the first 2-4 days of incubation, Fe2+ accumulated up to 100 µM in the top 2 mm due to Fe(III) photoreduction. After physical perturbation at day 7, Fe2+ was re-mobilized reaching concentrations of 320 µM in 30 mm depth, which decreased to below detection limit within 2 days afterward. Mössbauer spectroscopy showed that the relative abundance of metastable iron-sulfur mineral phases (FeSx) increased during initial incubation and decreased together with pyrite (FeS2) after perturbation. We show that Fe2+ mobilization in marine sediments is stimulated by chemical changes caused by physical disturbances impacting the Fe redox distribution. Our study suggests that, in addition to microbial and abiotic Fe(III) reduction, including Fe(III) photoreduction, physical mixing processes induce chemical changes providing sediments and the inhabiting microbial community with Fe2+.


Assuntos
Compostos Férricos , Sedimentos Geológicos , Compostos Ferrosos , Oxirredução , Enxofre
11.
Gerontology ; 66(5): 447-459, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32610336

RESUMO

Atherosclerosis - the pathophysiological mechanism shared by most cardiovascular diseases - can be directly or indirectly assessed by a variety of clinical tests including measurement of carotid intima-media thickness, carotid plaque, -ankle-brachial index, pulse wave velocity, and coronary -artery calcium. The Prospective Studies of Atherosclerosis -(Proof-ATHERO) consortium (https://clinicalepi.i-med.ac.at/research/proof-athero/) collates de-identified individual-participant data of studies with information on atherosclerosis measures, risk factors for cardiovascular disease, and incidence of cardiovascular diseases. It currently comprises 74 studies that involve 106,846 participants from 25 countries and over 40 cities. In summary, 21 studies recruited participants from the general population (n = 67,784), 16 from high-risk populations (n = 22,677), and 37 as part of clinical trials (n = 16,385). Baseline years of contributing studies range from April 1980 to July 2014; the latest follow-up was until June 2019. Mean age at baseline was 59 years (standard deviation: 10) and 50% were female. Over a total of 830,619 person-years of follow-up, 17,270 incident cardiovascular events (including coronary heart disease and stroke) and 13,270 deaths were recorded, corresponding to cumulative incidences of 2.1% and 1.6% per annum, respectively. The consortium is coordinated by the Clinical Epidemiology Team at the Medical University of Innsbruck, Austria. Contributing studies undergo a detailed data cleaning and harmonisation procedure before being incorporated in the Proof-ATHERO central database. Statistical analyses are being conducted according to pre-defined analysis plans and use established methods for individual-participant data meta-analysis. Capitalising on its large sample size, the multi-institutional collaborative Proof-ATHERO consortium aims to better characterise, understand, and predict the development of atherosclerosis and its clinical consequences.


Assuntos
Aterosclerose/diagnóstico , Idoso , Doenças Cardiovasculares/epidemiologia , Espessura Intima-Media Carotídea , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Prospectivos , Análise de Onda de Pulso , Projetos de Pesquisa , Medição de Risco , Fatores de Risco
12.
Environ Sci Technol ; 53(14): 8197-8204, 2019 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-31203607

RESUMO

Neutrophilic microbial aerobic oxidation of ferrous iron (Fe(II)) is restricted to pH-circumneutral environments characterized by low oxygen where microaerophilic Fe(II)-oxidizing microorganisms successfully compete with abiotic Fe(II) oxidation. However, accumulation of ferric (bio)minerals increases competition by stimulating abiotic surface-catalyzed heterogeneous Fe(II) oxidation. Here, we present an experimental approach that allows quantification of microbial and abiotic contribution to Fe(II) oxidation in the presence or initial absence of ferric (bio)minerals. We found that at 20 µM O2 and the initial absence of Fe(III) minerals, an iron(II)-oxidizing enrichment culture (99.6% similarity to Sideroxydans spp.) contributed 40% to the overall Fe(II) oxidation within approximately 26 h and oxidized up to 3.6 × 10-15 mol Fe(II) cell-1 h-1. Optimum O2 concentrations at which enzymatic Fe(II) oxidation can compete with abiotic Fe(II) oxidation ranged from 5 to 20 µM. Lower O2 levels limited biotic Fe(II) oxidation, while at higher O2 levels abiotic Fe(II) oxidation dominated. The presence of ferric (bio)minerals induced surface-catalytic heterogeneous abiotic Fe(II) oxidation and reduced the microbial contribution to Fe(II) oxidation from 40% to 10% at 10 µM O2. The obtained results will help to better assess the impact of microaerophilic Fe(II) oxidation on the biogeochemical iron cycle in a variety of environmental natural and anthropogenic settings.


Assuntos
Compostos Ferrosos , Ferro , Compostos Férricos , Minerais , Oxirredução , Oxigênio
13.
Ear Hear ; 40(2): 227-242, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-29847413

RESUMO

OBJECTIVES: This randomized controlled trial evaluated the efficacy of delivering coping skills education from Progressive Tinnitus Management (PTM) by telephone (Tele-PTM). The trial followed a previous pilot study that showed positive results for Tele-PTM. DESIGN: Participants included individuals with bothersome tinnitus (N = 205) located anywhere within the United States. A special emphasis was given to including individuals who had experienced one or more traumatic brain injuries (TBIs). Participants were randomized to either Tele-PTM intervention or 6-month wait-list control (WLC). The Tele-PTM intervention involved five telephone appointments-two led by an audiologist (teaching how to use therapeutic sound) and three by a psychologist (teaching coping skills derived from cognitive-behavioral therapy). It was hypothesized that Tele-PTM would be more effective than WLC in reducing functional effects of tinnitus as measured with the Tinnitus Functional Index. Additional outcome measures included the Self-Efficacy for Managing Reactions to Tinnitus questionnaire and the Hospital Anxiety and Depression Scale. The effect of Tele-PTM on outcomes was estimated using linear mixed models. RESULTS: Overall results showed convincingly that the Tele-PTM group had significantly better outcomes than the WLC group. These results were consistent across all outcome measures, indicating not only a reduction of tinnitus functional distress but also increased self-efficacy. Improvements in measures of anxiety and depression were also observed. Tele-PTM participants in all TBI categories showed significant improvement. CONCLUSIONS: Results provide strong support for use of Tele-PTM methodology for persons with bothersome tinnitus, regardless of whether the person also has TBI symptoms. The effect size for Tele-PTM was high for the primary outcome measure, the Tinnitus Functional Index, and all other outcome measures showed significant improvement. Combined with our previous pilot study, the Tele-PTM method is validated for potential nationwide provision of tinnitus services.


Assuntos
Estimulação Acústica/métodos , Adaptação Psicológica , Lesões Encefálicas Traumáticas/psicologia , Terapia Cognitivo-Comportamental/métodos , Educação de Pacientes como Assunto , Telefone , Zumbido/reabilitação , Adulto , Idoso , Idoso de 80 Anos ou mais , Ansiedade/psicologia , Audiologistas , Lesões Encefálicas Traumáticas/complicações , Estudos de Casos e Controles , Depressão/psicologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Psicologia , Autoeficácia , Telemedicina , Zumbido/complicações , Zumbido/psicologia , Resultado do Tratamento , Listas de Espera
14.
Environ Microbiol ; 20(10): 3462-3483, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30058270

RESUMO

Iron is the most abundant redox-active metal in the Earth's crust. The one electron transfer between the two most common redox states, Fe(II) and Fe(III), plays a role in a huge range of environmental processes from mineral formation and dissolution to contaminant remediation and global biogeochemical cycling. It has been appreciated for more than a century that microorganisms can harness the energy of this Fe redox transformation for their metabolic benefit. However, this is most widely understood for anaerobic Fe(III)-reducing or aerobic and microaerophilic Fe(II)-oxidizing bacteria. Only in the past few decades have we come to appreciate that bacteria also play a role in the anaerobic oxidation of ferrous iron, Fe(II), and thus can act to form Fe(III) minerals in anoxic settings. Since this discovery, our understanding of the ecology of these organisms, their mechanisms of Fe(II) oxidation and their role in environmental processes has been increasing rapidly. In this article, we bring these new discoveries together to review the current knowledge on these environmentally important bacteria, and reveal knowledge gaps for future research.


Assuntos
Bactérias/metabolismo , Compostos Ferrosos/metabolismo , Compostos Férricos/metabolismo , Oxirredução , Microbiologia do Solo , Microbiologia da Água
15.
Appl Environ Microbiol ; 84(2)2018 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-29101195

RESUMO

Nitrate-reducing iron(II)-oxidizing bacteria have been known for approximately 20 years. There has been much debate as to what extent the reduction of nitrate and the oxidation of ferrous iron are coupled via enzymatic pathways or via abiotic processes induced by nitrite formed by heterotrophic denitrification. The aim of the present study was to assess the coupling of nitrate reduction and iron(II) oxidation by monitoring changes in substrate concentrations, as well as in the activity of nitrate-reducing bacteria in natural littoral freshwater sediment, in response to stimulation with nitrate and iron(II). In substrate-amended microcosms, we found that the biotic oxidation of ferrous iron depended on the simultaneous microbial reduction of nitrate. Additionally, the abiotic oxidation of ferrous iron by nitrite in sterilized sediment was not fast enough to explain the iron oxidation rates observed in microbially active sediment. Furthermore, the expression levels of genes coding for enzymes crucial for nitrate reduction were in some setups stimulated by the presence of ferrous iron. These results indicate that there is a direct influence of ferrous iron on bacterial denitrification and support the hypothesis that microbial nitrate reduction is stimulated by biotic iron(II) oxidation.IMPORTANCE The coupling of nitrate reduction and Fe(II) oxidation affects the environment at a local scale, e.g., by changing nutrient or heavy metal mobility in soils due to the formation of Fe(III) minerals, as well as at a global scale, e.g., by the formation of the primary greenhouse gas nitrous oxide. Although the coupling of nitrate reduction and Fe(II) oxidation was reported 20 years ago and has been studied intensively since then, the underlying mechanisms still remain unknown. One of the main knowledge gaps is the extent of enzymatic Fe(II) oxidation coupled to nitrate reduction, which has frequently been questioned in the literature. In the present study, we provide evidence for microbially mediated nitrate-reducing Fe(II) oxidation in freshwater sediments. This evidence is based on the rates of nitrate reduction and Fe(II) oxidation determined in microcosm incubations and on the effect of iron on the expression of genes required for denitrification.


Assuntos
Bactérias/metabolismo , Compostos Ferrosos/metabolismo , Água Doce/microbiologia , Sedimentos Geológicos/microbiologia , Nitratos/metabolismo , Ciclo do Nitrogênio/fisiologia , Anaerobiose , Bactérias/genética , Desnitrificação , Compostos Férricos/metabolismo , Processos Heterotróficos , Ferro/metabolismo , Minerais/metabolismo , Nitritos/metabolismo , Oxirredução , Acoplamento Oxidativo
16.
Mol Cell Neurosci ; 78: 1-8, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27825984

RESUMO

Microglial motility is tightly controlled by multitude of agonistic and antagonistic factors. Chemoattractants, released after infection or damage of the brain, provoke directed migration of microglia to the pathogenic incident. In contrast, noradrenaline and other stress hormones have been shown to suppress microglial movement. Here we asked for the signaling reactions involved in the positive and negative control of microglial motility. Using pharmacological and genetic approaches we identified the lipid kinase activity of phosphoinositide 3-kinase species γ (PI3Kγ) as an essential mediator of microglial migration provoked by the complement component C5a and other chemoattractants. Inhibition of PI3Kγ lipid kinase activity by protein kinase A was disclosed as mechanism causing suppression of microglial migration by noradrenaline. Together these data characterize PI3Kγ as a nodal point in the control of microglial motility.


Assuntos
Agonistas alfa-Adrenérgicos/farmacologia , Fatores Quimiotáticos/farmacologia , Quimiotaxia , Microglia/metabolismo , Norepinefrina/farmacologia , Fosfatidilinositol 3-Quinases/metabolismo , Animais , Linhagem Celular , Células Cultivadas , Complemento C5a/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Microglia/efeitos dos fármacos , Microglia/fisiologia , Fosfatidilinositol 3-Quinases/genética
18.
Environ Microbiol ; 18(9): 3159-74, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27234371

RESUMO

Coastal marine sediments contain varying concentrations of iron, oxygen, nitrate and organic carbon. It is unknown how organic carbon content influences the activity of nitrate-reducing and phototrophic Fe(II)-oxidizers and microbial Fe-redox cycling in such sediments. Therefore, microcosms were prepared with two coastal marine sediments (Kalø Vig and Norsminde Fjord at Aarhus Bay, Denmark) varying in TOC from 0.4 to 3.0 wt%. The microcosms were incubated under light/dark conditions with/without addition of nitrate and/or Fe(II). Although most probable number (MPN) counts of phototrophic Fe(II)-oxidizers were five times lower in the low-TOC sediment, phototrophic Fe(II) oxidation rates were higher compared with the high-TOC sediment. Fe(III)-amended microcosms showed that this lower net Fe(II) oxidation in the high-TOC sediment is caused by concurrent bacterial Fe(III) reduction. In contrast, MPN counts of nitrate-reducing Fe(II)-oxidizers and net rates of nitrate-reducing Fe(II) oxidation were comparable in low- and high-TOC sediments. However, the ratio of nitratereduced :iron(II)oxidized was higher in the high-TOC sediment, suggesting that a part of the nitrate was reduced by mixotrophic nitrate-reducing Fe(II)-oxidizers and chemoorganoheterotrophic nitrate-reducers. Our results demonstrate that dynamic microbial Fe cycling occurs in these sediments and that the extent of Fe cycling is dependent on organic carbon content.


Assuntos
Bactérias/metabolismo , Carbono/metabolismo , Compostos Férricos/metabolismo , Compostos Ferrosos/metabolismo , Sedimentos Geológicos/microbiologia , Anaerobiose , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Carbono/análise , Dinamarca , Sedimentos Geológicos/química , Nitratos/metabolismo , Oxirredução
19.
Appl Environ Microbiol ; 82(5): 1433-1447, 2015 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-26682861

RESUMO

Iron is abundant in sediments, where it can be biogeochemically cycled between its divalent and trivalent redox states. The neutrophilic microbiological Fe cycle involves Fe(III)-reducing and three different physiological groups of Fe(II)-oxidizing microorganisms, i.e., microaerophilic, anoxygenic phototrophic, and nitrate-reducing Fe(II) oxidizers. However, it is unknown whether all three groups coexist in one habitat and how they are spatially distributed in relation to gradients of O2, light, nitrate, and Fe(II). We examined two coastal marine sediments in Aarhus Bay, Denmark, by cultivation and most probable number (MPN) studies for Fe(II) oxidizers and Fe(III) reducers and by quantitative-PCR (qPCR) assays for microaerophilic Fe(II) oxidizers. Our results demonstrate the coexistence of all three metabolic types of Fe(II) oxidizers and Fe(III) reducers. In qPCR, microaerophilic Fe(II) oxidizers (Zetaproteobacteria) were present with up to 3.2 × 10(6) cells g dry sediment(-1). In MPNs, nitrate-reducing Fe(II) oxidizers, anoxygenic phototrophic Fe(II) oxidizers, and Fe(III) reducers reached cell numbers of up to 3.5 × 10(4), 3.1 × 10(2), and 4.4 × 10(4) g dry sediment(-1), respectively. O2 and light penetrated only a few millimeters, but the depth distribution of the different iron metabolizers did not correlate with the profile of O2, Fe(II), or light. Instead, abundances were homogeneous within the upper 3 cm of the sediment, probably due to wave-induced sediment reworking and bioturbation. In microaerophilic Fe(II)-oxidizing enrichment cultures, strains belonging to the Zetaproteobacteria were identified. Photoferrotrophic enrichments contained strains related to Chlorobium and Rhodobacter; the nitrate-reducing Fe(II) enrichments contained strains related to Hoeflea and Denitromonas. This study shows the coexistence of all three types of Fe(II) oxidizers in two near-shore marine environments and the potential for competition and interrelationships between them.


Assuntos
Bactérias/isolamento & purificação , Biota , Compostos Férricos/metabolismo , Compostos Ferrosos/metabolismo , Sedimentos Geológicos/microbiologia , Nitratos/metabolismo , Processos Fototróficos , Aerobiose , Bactérias/classificação , Dinamarca , Oxirredução , Reação em Cadeia da Polimerase em Tempo Real
20.
BMC Public Health ; 15: 820, 2015 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-26303077

RESUMO

BACKGROUND: Self-efficacy has been determined to be a strong predictor of who will engage in physical activity. We aimed to evaluate the associations between self-efficacy to perform physical activity, self-reported leisure-time physical activity and cardiovascular events in a population-based cohort of middle-aged Swedish men with no previous cardiovascular disease, or treatment with cardiovascular drugs. METHODS: Analyses are based on 377 men randomly selected and stratified for weight and insulin sensitivity from a population sample of 58-year-old men (n = 1728) and who had answered a question about their competence to perform exercise (as an assessment of physical self-efficacy). The Saltin-Grimby Physical Activity Level Scale was used to assess self-reported levels of leisure-time physical activity. Cardiovascular events were recorded during 13-years of follow-up. RESULTS: The group with poor self-efficacy to perform physical activity had a significantly higher incidence of cardiovascular events compared with the group with good physical self-efficacy (32.1% vs 17.1%, p < 0.01). Multivariate analyses showed that poor physical self-efficacy was associated with an increased relative risk of 2.0 (95% CI 1.2 to 3.0), of having a cardiovascular event during follow-up also after adjustments for co-variates such as waist to hip ratio, heart rate, fasting plasma glucose, serum triglycerides, systolic blood pressure, apoB/apoA-I ratio and leisure-time physical activity. CONCLUSION: Self-efficacy to perform physical activity was strongly and independently associated with cardiovascular events and was superior to self-assessed physical activity in predicting cardiovascular events during 13-years of follow-up in a group of middle-aged men, without known CVD or treatment with cardiovascular drugs.


Assuntos
Doenças Cardiovasculares/epidemiologia , Exercício Físico/psicologia , Autorrelato , Adulto , Idoso , Pesos e Medidas Corporais , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Autoeficácia , Suécia/epidemiologia
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