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1.
Sensors (Basel) ; 23(7)2023 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-37050603

RESUMEN

This work aims to give an overview of wireless communication technologies (WCT) for underground applications. Difficulties regarding the harsh mining environment and operational constraints for WCT implementation and use are discussed. Selected technologies are then classified regarding underground mining-specific use cases in advanced mining operations. Use-case-based application categories such as 'automation and teleoperation', 'tracking and tracing' and 'Long-Range Underground Monitoring (LUM)' are defined. The use cases determine requirements for the operational suitability and also quantify evaluation criteria for the evaluation of WCT. The result is a comparison by category of the wireless technologies, which underlines potentials of different technologies for defined use cases, but it can be concluded that the technology always has to be evaluated within the use case and operational constraints.

2.
Int J Mol Sci ; 24(3)2023 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-36769295

RESUMEN

Gemfibrozil is a drug that has been used for over 40 years to lower triglycerides in blood. As a ligand for peroxisome proliferative-activated receptor-alpha (PPARα), which is expressed in many tissues, it induces the transcription of numerous genes for carbohydrate and lipid-metabolism. However, nothing is known about how intracellular lipid-homeostasis and, in particular, triglycerides are affected. As triglycerides are stored in lipid-droplets, which are known to be associated with many diseases, such as Alzheimer's disease, cancer, fatty liver disease and type-2 diabetes, treatment with gemfibrozil could adversely affect these diseases. To address the question whether gemfibrozil also affects intracellular lipid-levels, SH-SY5Y, HEK and Calu-3 cells, representing three different metabolically active organs (brain, lung and kidney), were incubated with gemfibrozil and subsequently analyzed semi-quantitatively by mass-spectrometry. Importantly, all cells showed a strong increase in intracellular triglycerides (SH-SY5Y: 170.3%; HEK: 272.1%; Calu-3: 448.1%), suggesting that the decreased triglyceride-levels might be due to an enhanced cellular uptake. Besides the common intracellular triglyceride increase, a cell-line specific alteration in acylcarnitines are found, suggesting that especially in neuronal cell lines gemfibrozil increases the transport of fatty acids to mitochondria and therefore increases the turnover of fatty acids for the benefit of additional energy supply, which could be important in diseases, such as Alzheimer's disease.


Asunto(s)
Enfermedad de Alzheimer , Neuroblastoma , Humanos , Gemfibrozilo/farmacología , Enfermedad de Alzheimer/tratamiento farmacológico , Neuroblastoma/tratamiento farmacológico , Triglicéridos/metabolismo , Ácidos Grasos , Hipolipemiantes/farmacología , Hipolipemiantes/uso terapéutico
3.
Stat Med ; 41(17): 3421-3433, 2022 07 30.
Artículo en Inglés | MEDLINE | ID: mdl-35582814

RESUMEN

Many clinical trials repeatedly measure several longitudinal outcomes on patients. Patient follow-up can discontinue due to an outcome-dependent event, such as clinical diagnosis, death, or dropout. Joint modeling is a popular choice for the analysis of this type of data. Using example data from a prodromal Alzheimer's disease trial, we propose a new type of multivariate joint model in which longitudinal brain imaging outcomes and memory impairment ratings are allowed to be associated both with time to open-label medication and dropout, and where the brain imaging outcomes may also directly affect the memory impairment ratings. Existing joint models for multivariate longitudinal outcomes account for the correlation between the longitudinal outcomes through the random effects, often by assuming a multivariate normal distribution. However, for these models, it is difficult to interpret how the longitudinal outcomes affect each other. We model the dependence between the longitudinal outcomes differently so that a first longitudinal outcome affects a second one. Specifically, for each longitudinal outcome, we use a linear mixed-effects model to estimate its trajectory, where, for the second longitudinal outcome, we include the linear predictor of the first outcome as a time-varying covariate. This facilitates an easy and direct interpretation of the association between the longitudinal outcomes and provides a framework for latent mediation analysis to understand the underlying biological processes. For the trial considered here, we found that part of the intervention effect is mediated through hippocampal brain atrophy. The proposed joint models are fitted using a Bayesian framework via MCMC simulation.


Asunto(s)
Enfermedad de Alzheimer , Fenómenos Biológicos , Enfermedad de Alzheimer/diagnóstico por imagen , Enfermedad de Alzheimer/tratamiento farmacológico , Teorema de Bayes , Humanos , Modelos Lineales , Estudios Longitudinales , Modelos Estadísticos
4.
Int J Mol Sci ; 23(24)2022 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-36555176

RESUMEN

Administration of systemic retinoids such as acitretin has not been approved yet for pediatric patients. An adverse event of retinoid-therapy that occurs with lower prevalence in children than in adults is hyperlipidemia. This might be based on the lack of comorbidities in young patients, but must not be neglected. Especially for the development of the human brain up to young adulthood, dysbalance of lipids might be deleterious. Here, we provide for the first time an in-depth analysis of the influence of subchronic acitretin-administration on lipid composition of brain parenchyma of young wild type mice. For comparison and to evaluate the systemic effect of the treatment, liver lipids were analogously investigated. As expected, triglycerides increased in liver as well as in brain and a non-significant increase in cholesterol was observed. However, specifically brain showed an increase in lyso-phosphatidylcholine and carnitine as well as in sphingomyelin. Group analysis of lipid classes revealed no statistical effects, while single species were tissue-dependently changed: effects in brain were in general more subtly as compared to those in liver regarding the mere number of changed lipid species. Thus, while the overall impact of acitretin seems comparably small regarding brain, the change in individual species and their role in brain development and maturation has to be considered.


Asunto(s)
Acitretina , Hiperlipidemias , Adulto , Humanos , Niño , Adolescente , Animales , Ratones , Adulto Joven , Acitretina/farmacología , Acitretina/uso terapéutico , Lipidómica , Hiperlipidemias/inducido químicamente , Colesterol , Encéfalo
5.
Int J Mol Sci ; 23(4)2022 Feb 18.
Artículo en Inglés | MEDLINE | ID: mdl-35216410

RESUMEN

Alzheimer's disease (AD) is characterized by an increased plaque burden and tangle accumulation in the brain accompanied by extensive lipid alterations. Methylxanthines (MTXs) are alkaloids frequently consumed by dietary intake known to interfere with the molecular mechanisms leading to AD. Besides the fact that MTX consumption is associated with changes in triglycerides and cholesterol in serum and liver, little is known about the effect of MTXs on other lipid classes, which raises the question of whether MTX can alter lipids in a way that may be relevant in AD. Here we have analyzed naturally occurring MTXs caffeine, theobromine, theophylline, and the synthetic MTXs pentoxifylline and propentofylline also used as drugs in different neuroblastoma cell lines. Our results show that lipid alterations are not limited to triglycerides and cholesterol in the liver and serum, but also include changes in sphingomyelins, ceramides, phosphatidylcholine, and plasmalogens in neuroblastoma cells. These changes comprise alterations known to be beneficial, but also adverse effects regarding AD were observed. Our results give an additional perspective of the complex link between MTX and AD, and suggest combining MTX with a lipid-altering diet compensating the adverse effects of MTX rather than using MTX alone to prevent or treat AD.


Asunto(s)
Enfermedad de Alzheimer/metabolismo , Lípidos/fisiología , Neuroblastoma/metabolismo , Enfermedades Neurodegenerativas/metabolismo , Xantinas/farmacología , Cafeína/farmacología , Línea Celular Tumoral , Colesterol/metabolismo , Humanos , Células-Madre Neurales/efectos de los fármacos , Células-Madre Neurales/metabolismo , Pentoxifilina/farmacología , Teobromina/farmacología , Teofilina/farmacología , Triglicéridos/metabolismo
6.
Alzheimers Dement ; 17(1): 29-40, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-32920957

RESUMEN

INTRODUCTION: The LipiDiDiet trial investigates the effects of the specific multinutrient combination Fortasyn Connect on cognition and related measures in prodromal Alzheimer's disease (AD). Based on previous results we hypothesized that benefits increase with long-term intervention. METHODS: In this randomized, double-blind, placebo-controlled trial, 311 people with prodromal AD were recruited using the International Working Group-1 criteria and assigned to active product (125 mL once-a-day drink) or an isocaloric, same tasting, placebo control drink. Main outcome was change in cognition (Neuropsychological Test Battery [NTB] 5-item composite). Analyses were by modified intention-to-treat, excluding (ie, censoring) data collected after the start of open-label active product and/or AD medication. RESULTS: Of the 382 assessed for eligibility, 311 were randomized, of those 162 participants completed the 36-month study, including 81 with 36-month data eligible for efficacy analysis. Over 36 months, significant reductions in decline were observed for the NTB 5-item composite (-60%; between-group difference 0.212 [95% confidence interval: 0.044 to 0.380]; P = 0.014), Clinical Dementia Rating-Sum of Boxes (-45%; P = 0.014), memory (-76%; P = 0.008), and brain atrophy measures; small to medium Cohen's d effect size (0.25-0.31) similar to established clinically relevant AD treatment. DISCUSSION: This multinutrient intervention slowed decline on clinical and other measures related to cognition, function, brain atrophy, and disease progression. These results indicate that intervention benefits increased with long-term use.


Asunto(s)
Enfermedad de Alzheimer/dietoterapia , Síntomas Prodrómicos , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/diagnóstico por imagen , Enfermedad de Alzheimer/psicología , Atrofia , Cognición , Disfunción Cognitiva/dietoterapia , Método Doble Ciego , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Pruebas de Estado Mental y Demencia , Persona de Mediana Edad , Pruebas Neuropsicológicas , Terapia Nutricional , Factores de Riesgo
7.
Environ Res ; 184: 109319, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32151842

RESUMEN

Phosphorus (P) is an essential and limiting nutrient for agricultural systems, where the demand for agricultural products such as food, feed, and bio-fuel are the major drivers of the intensification of agricultural production systems. Globally, maize is one of three main cereal crops, a main feedstock for animal production and a substrate for the production of bio-ethanol. This study investigated P flows through the multiple utilization systems of maize (as represented by the subsystems of food, feed and energy production) at a crop level of 2016 as reference year and made future predictions of P flows for the year 2030 based on different scenarios for food-feed-energy systems in China. For 2016, the subsystem of animal production resulted in the highest waste of P due to inappropriate manure management, but the subsystem of value-added products (Bio-fuel production, distillers dried grains with solubles (DDGS), maize-oil) showed the lowest P use efficiency (39%). From the value-added subsystem, 17% of P from the process flow to the subsystem of animal production as DDGS, and 61% of P is wasted associated with wastewater and sludge. Future scenarios of structural adjustments in the maize consumption system predict that the supply of maize for animal feed will be threatened if the policy of the Biofuel National Promotion before 2020 is fully implemented in China, as current maize production will not meet the future demand of food, feed and energy simultaneously. The results emphasized the use of P waste resources and better sludge management from a systems perspective. This also implied the importance of exploring coordinated development and integrated strategies for sustainable P flow management in multiple utilization systems.


Asunto(s)
Fósforo , Zea mays , Alimentación Animal/análisis , Animales , China , Grano Comestible/química , Fósforo/análisis
8.
Cell Mol Life Sci ; 76(5): 1005-1025, 2019 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-30599067

RESUMEN

BACKGROUND: The ADAM10-mediated cleavage of transmembrane proteins regulates cellular processes such as proliferation or migration. Substrate cleavage by ADAM10 has also been implicated in pathological situations such as cancer or Morbus Alzheimer. Therefore, identifying endogenous molecules, which modulate the amount and consequently the activity of ADAM10, might contribute to a deeper understanding of the enzyme's role in both, physiology and pathology. METHOD: To elucidate the underlying cellular mechanism of the TBX2-mediated repression of ADAM10 gene expression, we performed overexpression, RNAi-mediated knockdown and pharmacological inhibition studies in the human neuroblastoma cell line SH-SY5Y. Expression analysis was conducted by e.g. real-time RT-PCR or western blot techniques. To identify the binding region of TBX2 within the ADAM10 promoter, we used luciferase reporter assay on deletion constructs and EMSA/WEMSA experiments. In addition, we analyzed a TBX2 loss-of-function Drosophila model regarding the expression of ADAM10 orthologs by qPCR. Furthermore, we quantified the mRNA level of TBX2 in post-mortem brain tissue of AD patients. RESULTS: Here, we report TBX2 as a transcriptional repressor of ADAM10 gene expression: both, the DNA-binding domain and the repression domain of TBX2 were necessary to effect transcriptional repression of ADAM10 in neuronal SH-SY5Y cells. This regulatory mechanism required HDAC1 as a co-factor of TBX2. Transcriptional repression was mediated by two functional TBX2 binding sites within the core promoter sequence (- 315 to - 286 bp). Analysis of a TBX2 loss-of-function Drosophila model revealed that kuzbanian and kuzbanian-like, orthologs of ADAM10, were derepressed compared to wild type. Vice versa, analysis of cortical brain samples of AD-patients, which showed reduced ADAM10 mRNA levels, revealed a 2.5-fold elevation of TBX2, while TBX3 and TBX21 levels were not affected. CONCLUSION: Our results characterize TBX2 as a repressor of ADAM10 gene expression and suggest that this regulatory interaction is conserved across tissues and species.


Asunto(s)
Proteína ADAM10/genética , Enfermedad de Alzheimer/etiología , Regulación de la Expresión Génica , Proteínas de Dominio T Box/fisiología , Secretasas de la Proteína Precursora del Amiloide/genética , Animales , Ácido Aspártico Endopeptidasas/genética , Sitios de Unión , Encéfalo/metabolismo , Células Cultivadas , Desintegrinas/genética , Drosophila , Proteínas de Drosophila/genética , Histona Desacetilasa 1/fisiología , Humanos , Metaloendopeptidasas/genética , Ratones , Ratones Endogámicos C57BL , Neuronas/metabolismo , Regiones Promotoras Genéticas , Proteínas de Dominio T Box/química , Transcripción Genética
9.
Alzheimers Dement ; 16(7): 1078-1094, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32627328

RESUMEN

Reducing the risk of dementia can halt the worldwide increase of affected people. The multifactorial and heterogeneous nature of late-onset dementia, including Alzheimer's disease (AD), indicates a potential impact of multidomain lifestyle interventions on risk reduction. The positive results of the landmark multidomain Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) support such an approach. The World-Wide FINGERS (WW-FINGERS), launched in 2017 and including over 25 countries, is the first global network of multidomain lifestyle intervention trials for dementia risk reduction and prevention. WW-FINGERS aims to adapt, test, and optimize the FINGER model to reduce risk across the spectrum of cognitive decline-from at-risk asymptomatic states to early symptomatic stages-in different geographical, cultural, and economic settings. WW-FINGERS aims to harmonize and adapt multidomain interventions across various countries and settings, to facilitate data sharing and analysis across studies, and to promote international joint initiatives to identify globally implementable and effective preventive strategies.


Asunto(s)
Enfermedad de Alzheimer/prevención & control , Demencia/prevención & control , Terapia por Ejercicio , Estilo de Vida , Ensayos Clínicos como Asunto , Cognición/fisiología , Humanos , Proyectos de Investigación , Conducta de Reducción del Riesgo
10.
Int J Mol Sci ; 21(23)2020 Nov 27.
Artículo en Inglés | MEDLINE | ID: mdl-33260941

RESUMEN

Methylxanthines are a group of substances derived from the purine base xanthine with a methyl group at the nitrogen on position 3 and different residues at the nitrogen on position 1 and 7. They are widely consumed in nutrition and used as pharmaceuticals. Here we investigate the transcriptional regulation of 83 genes linked to Alzheimer's disease in the presence of five methylxanthines, including the most prominent naturally occurring methylxanthines-caffeine, theophylline and theobromine-and the synthetic methylxanthines pentoxifylline and propentofylline. Methylxanthine-regulated genes were found in pathways involved in processes including oxidative stress, lipid homeostasis, signal transduction, transcriptional regulation, as well as pathways involved in neuronal function. Interestingly, multivariate analysis revealed different or inverse effects on gene regulation for caffeine compared to the other methylxanthines, which was further substantiated by multiple comparison analysis, pointing out a distinct role for caffeine in gene regulation. Our results not only underline the beneficial effects of methylxanthines in the regulation of genes in neuroblastoma wild-type cells linked to neurodegenerative diseases in general, but also demonstrate that individual methylxanthines like caffeine mediate unique or inverse expression patterns. This suggests that the replacement of single methylxanthines by others could result in unexpected effects, which could not be anticipated by the comparison to other substances in this substance class.


Asunto(s)
Enfermedad de Alzheimer/genética , Cafeína/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Neuroblastoma/genética , Xantinas/farmacología , Línea Celular Tumoral , Genes Esenciales , Humanos , Pentoxifilina/farmacología , Análisis de Componente Principal , Teobromina/farmacología , Teofilina/farmacología , Transcripción Genética/efectos de los fármacos , Xantinas/química
11.
BMC Med Res Methodol ; 19(1): 163, 2019 07 25.
Artículo en Inglés | MEDLINE | ID: mdl-31345172

RESUMEN

BACKGROUND: Many prodromal Alzheimer's disease trials collect two types of data: the time until clinical diagnosis of dementia and longitudinal patient information. These data are often analysed separately, although they are strongly associated. By combining the longitudinal and survival data into a single statistical model, joint models can account for the dependencies between the two types of data. METHODS: We illustrate the major steps in a joint modelling approach, motivated by data from a prodromal Alzheimer's disease study: the LipiDiDiet trial. RESULTS: By using joint models we are able to disentangle baseline confounding from the intervention effect and moreover, to investigate the association between longitudinal patient information and the time until clinical dementia diagnosis. CONCLUSIONS: Joint models provide a valuable tool in the statistical analysis of clinical studies with longitudinal and survival data, such as in prodromal Alzheimer's disease trials, and have several added values compared to separate analyses.


Asunto(s)
Enfermedad de Alzheimer/dietoterapia , Ácidos Docosahexaenoicos/uso terapéutico , Ácido Eicosapentaenoico/uso terapéutico , Fosfolípidos/uso terapéutico , Proyectos de Investigación , Anciano , Enfermedad de Alzheimer/diagnóstico , Progresión de la Enfermedad , Método Doble Ciego , Femenino , Humanos , Análisis de Intención de Tratar , Masculino , Pruebas Neuropsicológicas , Síntomas Prodrómicos
14.
J Lipid Res ; 58(11): 2083-2101, 2017 11.
Artículo en Inglés | MEDLINE | ID: mdl-28528321

RESUMEN

In the last decade, it has become obvious that Alzheimer's disease (AD) is closely linked to changes in lipids or lipid metabolism. One of the main pathological hallmarks of AD is amyloid-ß (Aß) deposition. Aß is derived from sequential proteolytic processing of the amyloid precursor protein (APP). Interestingly, both, the APP and all APP secretases are transmembrane proteins that cleave APP close to and in the lipid bilayer. Moreover, apoE4 has been identified as the most prevalent genetic risk factor for AD. ApoE is the main lipoprotein in the brain, which has an abundant role in the transport of lipids and brain lipid metabolism. Several lipidomic approaches revealed changes in the lipid levels of cerebrospinal fluid or in post mortem AD brains. Here, we review the impact of apoE and lipids in AD, focusing on the major brain lipid classes, sphingomyelin, plasmalogens, gangliosides, sulfatides, DHA, and EPA, as well as on lipid signaling molecules, like ceramide and sphingosine-1-phosphate. As nutritional approaches showed limited beneficial effects in clinical studies, the opportunities of combining different supplements in multi-nutritional approaches are discussed and summarized.


Asunto(s)
Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/prevención & control , Apolipoproteínas E/metabolismo , Ácidos Grasos Omega-3/metabolismo , Alimentos , Enfermedad de Alzheimer/dietoterapia , Animales , Humanos
15.
Nat Chem Biol ; 11(10): 779-83, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26322824

RESUMEN

Aldehyde oxidase (AOX) is a xanthine oxidase (XO)-related enzyme with emerging importance due to its role in the metabolism of drugs and xenobiotics. We report the first crystal structures of human AOX1, substrate free (2.6-Å resolution) and in complex with the substrate phthalazine and the inhibitor thioridazine (2.7-Å resolution). Analysis of the protein active site combined with steady-state kinetic studies highlight the unique features, including binding and substrate orientation at the active site, that characterize human AOX1 as an important drug-metabolizing enzyme. Structural analysis of the complex with the noncompetitive inhibitor thioridazine revealed a new, unexpected and fully occupied inhibitor-binding site that is structurally conserved among mammalian AOXs and XO. The new structural insights into the catalytic and inhibition mechanisms of human AOX that we now report will be of great value for the rational analysis of clinical drug interactions involving inhibition of AOX1 and for the prediction and design of AOX-stable putative drugs.


Asunto(s)
Aldehído Oxidasa/química , Aldehído Oxidasa/metabolismo , Inhibidores Enzimáticos/metabolismo , Xenobióticos/metabolismo , Aldehído Oxidasa/antagonistas & inhibidores , Aldehído Oxidasa/genética , Aldehído Oxidorreductasas/antagonistas & inhibidores , Aldehído Oxidorreductasas/química , Aldehído Oxidorreductasas/genética , Aldehído Oxidorreductasas/metabolismo , Animales , Dominio Catalítico , Cristalografía por Rayos X , Inhibidores Enzimáticos/química , Escherichia coli/genética , Humanos , Ratones , Modelos Moleculares , Unión Proteica , Conformación Proteica , Especificidad de la Especie , Especificidad por Sustrato , Xenobióticos/química
17.
Int J Mol Sci ; 18(12)2017 Dec 19.
Artículo en Inglés | MEDLINE | ID: mdl-29257109

RESUMEN

Alzheimer's disease (AD) is characterized by extracellular plaques in the brain, mainly consisting of amyloid-ß (Aß), as derived from sequential cleavage of the amyloid precursor protein. Epidemiological studies suggest a tight link between hypovitaminosis of the secosteroid vitamin D and AD. Besides decreased vitamin D level in AD patients, an effect of vitamin D on Aß-homeostasis is discussed. However, the exact underlying mechanisms remain to be elucidated and nothing is known about the potential effect of vitamin D analogues. Here we systematically investigate the effect of vitamin D and therapeutically used analogues (maxacalcitol, calcipotriol, alfacalcidol, paricalcitol, doxercalciferol) on AD-relevant mechanisms. D2 and D3 analogues decreased Aß-production and increased Aß-degradation in neuroblastoma cells or vitamin D deficient mouse brains. Effects were mediated by affecting the Aß-producing enzymes BACE1 and γ-secretase. A reduced secretase activity was accompanied by a decreased BACE1 protein level and nicastrin expression, an essential component of the γ-secretase. Vitamin D and analogues decreased ß-secretase activity, not only in mouse brains with mild vitamin D hypovitaminosis, but also in non-deficient mouse brains. Our results further strengthen the link between AD and vitamin D, suggesting that supplementation of vitamin D or vitamin D analogues might have beneficial effects in AD prevention.


Asunto(s)
Péptidos beta-Amiloides/metabolismo , Placa Amiloide/tratamiento farmacológico , Proteolisis , Vitamina D/uso terapéutico , Vitaminas/uso terapéutico , Secretasas de la Proteína Precursora del Amiloide/genética , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Animales , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Línea Celular Tumoral , Femenino , Humanos , Ratones , Ratones Endogámicos C57BL , Vitamina D/administración & dosificación , Vitamina D/farmacología , Vitaminas/administración & dosificación , Vitaminas/farmacología
18.
Biochemistry ; 55(16): 2381-9, 2016 04 26.
Artículo en Inglés | MEDLINE | ID: mdl-27054466

RESUMEN

Formate dehydrogenases (FDHs) are capable of performing the reversible oxidation of formate and are enzymes of great interest for fuel cell applications and for the production of reduced carbon compounds as energy sources from CO2. Metal-containing FDHs in general contain a highly conserved active site, comprising a molybdenum (or tungsten) center coordinated by two molybdopterin guanine dinucleotide molecules, a sulfido and a (seleno-)cysteine ligand, in addition to a histidine and arginine residue in the second coordination sphere. So far, the role of these amino acids in catalysis has not been studied in detail, because of the lack of suitable expression systems and the lability or oxygen sensitivity of the enzymes. Here, the roles of these active site residues is revealed using the Mo-containing FDH from Rhodobacter capsulatus. Our results show that the cysteine ligand at the Mo ion is displaced by the formate substrate during the reaction, the arginine has a direct role in substrate binding and stabilization, and the histidine elevates the pKa of the active site cysteine. We further found that in addition to reversible formate oxidation, the enzyme is further capable of reducing nitrate to nitrite. We propose a mechanistic scheme that combines both functionalities and provides important insights into the distinct mechanisms of C-H bond cleavage and oxygen atom transfer catalyzed by formate dehydrogenase.


Asunto(s)
Formiato Deshidrogenasas/metabolismo , Molibdeno/metabolismo , Oxígeno/metabolismo , Rhodobacter capsulatus/enzimología , Dominio Catalítico , Cisteína/química , Cisteína/metabolismo , Formiato Deshidrogenasas/química , Formiatos/metabolismo , Modelos Moleculares , Molibdeno/química , Nitratos/metabolismo , Oxidación-Reducción , Rhodobacter capsulatus/química , Rhodobacter capsulatus/metabolismo
19.
Biochim Biophys Acta ; 1854(9): 1090-100, 2015 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-25514355

RESUMEN

The global carbon cycle depends on the biological transformations of C1 compounds, which include the reductive incorporation of CO2into organic molecules (e.g. in photosynthesis and other autotrophic pathways), in addition to the production of CO2from formate, a reaction that is catalyzed by formate dehydrogenases (FDHs). FDHs catalyze, in general, the oxidation of formate to CO2and H⁺. However, selected enzymes were identified to act as CO2reductases, which are able to reduce CO2to formate under physiological conditions. This reaction is of interest for the generation of formate as a convenient storage form of H2for future applications. Cofactor-containing FDHs are found in anaerobic bacteria and archaea, in addition to facultative anaerobic or aerobic bacteria. These enzymes are highly diverse and employ different cofactors such as the molybdenum cofactor (Moco), FeS clusters and flavins, or cytochromes. Some enzymes include tungsten (W) in place of molybdenum (Mo) at the active site. For catalytic activity, a selenocysteine (SeCys) or cysteine (Cys) ligand at the Mo atom in the active site is essential for the reaction. This review will focus on the characterization of Mo- and W-containing FDHs from bacteria, their active site structure, subunit compositions and its proposed catalytic mechanism. We will give an overview on the different mechanisms of substrate conversion available so far, in addition to providing an outlook on bio-applications of FDHs. This article is part of a Special Issue entitled: Cofactor-dependent proteins: evolution, chemical diversity and bio-applications.


Asunto(s)
Bacterias/enzimología , Formiato Deshidrogenasas/química , Molibdeno/química , Tungsteno/química , Catálisis , Dominio Catalítico , Formiato Deshidrogenasas/metabolismo
20.
Biochem Cell Biol ; 94(6): 534-542, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-27813426

RESUMEN

Omega-3 polyunsaturated fatty acids (PUFAs) have been proposed to be highly beneficial in Alzheimer's disease (AD). AD pathology is closely linked to an overproduction and accumulation of amyloid-ß (Aß) peptides as extracellular senile plaques in the brain. Total Aß levels are not only dependent on its production by proteolytic processing of the amyloid precursor protein (APP), but also on Aß-clearance mechanisms, including Aß-degrading enzymes. Here we show that the omega-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) increase Aß-degradation by affecting insulin-degrading enzyme (IDE), the major Aß-degrading enzyme secreted into the extracellular space of neuronal and microglial cells. The identification of the molecular mechanisms revealed that EPA directly increases IDE enzyme activity and elevates gene expression of IDE. DHA also directly stimulates IDE enzyme activity and affects IDE sorting by increasing exosome release of IDE, resulting in enhanced Aß-degradation in the extracellular milieu. Apart from the known positive effect of DHA in reducing Aß production, EPA and DHA might ameliorate AD pathology by increasing Aß turnover.


Asunto(s)
Péptidos beta-Amiloides/metabolismo , Ácidos Docosahexaenoicos/farmacología , Ácido Eicosapentaenoico/farmacología , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Insulisina/genética , Neuroblastoma/metabolismo , Animales , Western Blotting , Supervivencia Celular/efectos de los fármacos , Insulisina/metabolismo , Ratones , Neuroblastoma/tratamiento farmacológico , Neuroblastoma/genética , Neuroblastoma/patología , Regiones Promotoras Genéticas , ARN Mensajero/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Células Tumorales Cultivadas
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