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Effect of organic and inorganic nitrates on cerebrovascular pulsatile power transmission in patients with heart failure and preserved ejection fraction.
Londono-Hoyos, F, Zamani, P, Beraun, M, Vasim, I, Segers, P, Chirinos, JA
Physiological measurement. 2018;(4):044001
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Abstract
OBJECTIVE Increased penetration of pulsatile power to the brain has been implicated in the pathogenesis of age-related cognitive dysfunction and dementia, a common comorbidity in patients with heart failure and preserved ejection fraction (HFpEF). However, there is a lack of knowledge on the effects of organic and inorganic nitrates administration in this population on the power carried by pressure and flow waves traveling through the proximal aorta and penetrating the carotid artery into the brain microvasculature. APPROACH We assessed aortic and carotid hemodynamics non-invasively in two sub-studies: (1) at baseline and after administration of 0.4 mg of sublingual nitroglycerine (an organic nitrate; n = 26); and (2) in a randomized controlled trial of placebo (PB) versus inorganic nitrate administration (beetroot-juice (BR), 12.9 mmol NO3; n = 16). MAIN RESULTS Wave and hydraulic power analysis demonstrated that NTG increased total hydraulic power (from 5.68% at baseline to 8.62%, P = 0.001) and energy penetration (from 8.69% to 11.63%; P = 0.01) from the aorta to the carotid, while inorganic nitrate administration did not induce significant changes in aortic and carotid wave power (power: 5.49%PB versus 6.25%BR, P = 0.49; energy: 8.89%PB versus 10.65%BR, P = 0.27). SIGNIFICANCE Organic nitrates, but not inorganic nitrates, increase the amount of hydraulic energy transmitted into the carotid artery in subjects with HFpEF. These findings may have implications for the adverse effect profiles of these agents (such as the differential incidence of headaches) and for the pulsatile hemodynamic stress of the brain microvasculature in this patient population.
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Effect of diet and gut environment on the gastrointestinal formation of N-nitroso compounds: A review.
Kobayashi, J
Nitric oxide : biology and chemistry. 2018;:66-73
Abstract
Diet is associated with the development of cancer in the gastrointestinal (GI) tract, because dietary nitrate and nitrite are the main nitrosating agents that are responsible for the formation of carcinogenic N-nitroso compounds (NOCs) when nitrosatable substrates, such as amine and amide, are present in the GI tract. However, whether the nitroso compounds become beneficial S-nitroso compounds or carcinogenic NOCs might depend on dietary and environmental factors including food stuffs, gastric acidity, microbial flora, and the mean transit time of digesta. This review focused on GI NOC formation and environmental risk factors affecting its formation to provide appropriate nutritional strategies to prevent the development of GI cancer.
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Dietary Nitrate Supplementation Reduces Circulating Platelet-Derived Extracellular Vesicles in Coronary Artery Disease Patients on Clopidogrel Therapy: A Randomised, Double-Blind, Placebo-Controlled Study.
Burnley-Hall, N, Abdul, F, Androshchuk, V, Morris, K, Ossei-Gerning, N, Anderson, R, Rees, DA, James, PE
Thrombosis and haemostasis. 2018;(1):112-122
Abstract
Extracellular vesicles (EVs) are implicated in the pathogenesis of cardiovascular disease (CVD). Specifically, platelet-derived EVs are highly pro-coagulant, promoting thrombin generation and fibrin clot formation. Nitrate supplementation exerts beneficial effects in CVD, via an increase in nitric oxide (NO) bioavailability. Clopidogrel is capable of producing NO-donating compounds, such as S-nitrosothiols (RSNO) in the presence of nitrite and low pH. The aim of this study was to assess the effect of nitrate supplementation with versus without clopidogrel therapy on circulating EVs in coronary artery disease (CAD) patients. In this randomized, double-blind, placebo-controlled study, CAD patients with (n = 10) or without (n = 10) clopidogrel therapy received a dietary nitrate supplement (SiS nitrate gel) or identical placebo. NO metabolites and platelet activation were measured using ozone-based chemiluminescence and multiple electrode aggregometry. EV concentration and origin were determined using nanoparticle tracking analysis and time-resolved fluorescence. Following nitrate supplementation, plasma RSNO was elevated (4.7 ± 0.8 vs 0.2 ± 0.5 nM) and thrombin-receptor mediated platelet aggregation was reduced (-19.9 ± 6.0 vs 4.0 ± 6.4 U) only in the clopidogrel group compared with placebo. Circulating EVs were significantly reduced in this group (-1.183e11 ± 3.15e10 vs -9.93e9 ± 1.84e10 EVs/mL), specifically the proportion of CD41+ EVs (-2,120 ± 728 vs 235 ± 436 RFU [relative fluorescence unit]) compared with placebo. In vitro experiments demonstrated clopidogrel-SNO can reduce platelet-EV directly (6.209e10 ± 4.074e9 vs 3.94e11 ± 1.91e10 EVs/mL). In conclusion, nitrate supplementation reduces platelet-derived EVs in CAD patients on clopidogrel therapy, increasing patient responsiveness to clopidogrel. Nitrate supplementation may represent a novel approach to moderating the risk of thrombus formation in CAD patients.
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Molecular Regulation of Nitrate Responses in Plants.
Zhao, L, Liu, F, Crawford, NM, Wang, Y
International journal of molecular sciences. 2018;(7)
Abstract
Nitrogen is an essential macronutrient that affects plant growth and development. Improving the nitrogen use efficiency of crops is of great importance for the economic and environmental sustainability of agriculture. Nitrate (NO₃-) is a major form of nitrogen absorbed by most crops and also serves as a vital signaling molecule. Research has identified key molecular components in nitrate signaling mainly by employing forward and reverse genetics as well as systems biology. In this review, we focus on advances in the characterization of genes involved in primary nitrate responses as well as the long-term effects of nitrate, especially in terms of how nitrate regulates root development.
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Nitrate supplementation improves physical performance specifically in non-athletes during prolonged open-ended tests: a systematic review and meta-analysis.
Campos, HO, Drummond, LR, Rodrigues, QT, Machado, FSM, Pires, W, Wanner, SP, Coimbra, CC
The British journal of nutrition. 2018;(6):636-657
Abstract
Nitrate (NO3 -) is an ergogenic nutritional supplement that is widely used to improve physical performance. However, the effectiveness of NO3 - supplementation has not been systematically investigated in individuals with different physical fitness levels. The present study analysed whether different fitness levels (non-athletes v. athletes or classification of performance levels), duration of the test used to measure performance (short v. long duration) and the test protocol (time trials v. open-ended tests v. graded-exercise tests) influence the effects of NO3 - supplementation on performance. This systematic review and meta-analysis was conducted and reported according to the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. A systematic search of electronic databases, including PubMed, Web of Science, SPORTDiscus and ProQuest, was performed in August 2017. On the basis of the search and inclusion criteria, fifty-four and fifty-three placebo-controlled studies evaluating the effects of NO3 - supplementation on performance in humans were included in the systematic review and meta-analysis, respectively. NO3 - supplementation was ergogenic in non-athletes (mean effect size (ES) 0·25; 95 % CI 0·11, 0·38), particularly in evaluations of performance using long-duration open-ended tests (ES 0·47; 95 % CI 0·23, 0·71). In contrast, NO3 - supplementation did not enhance the performance of athletes (ES 0·04; 95 % CI -0·05, 0·15). After objectively classifying the participants into different performance levels, the frequency of trials showing ergogenic effects in individuals classified at lower levels was higher than that in individuals classified at higher levels. Thus, the present study indicates that dietary NO3 - supplementation improves physical performance in non-athletes, particularly during long-duration open-ended tests.
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Nitrate uptake and its regulation in relation to improving nitrogen use efficiency in cereals.
Plett, DC, Holtham, LR, Okamoto, M, Garnett, TP
Seminars in cell & developmental biology. 2018;:97-104
Abstract
On average less than half of the applied N is captured by crops, thus there is scope and need to improve N uptake in cereals. With nitrate (NO3-) being the main form of N available to cereal crops there has been a significant global research effort to understand plant NO3- uptake. Despite this, our knowledge of the NO3- uptake system is not sufficient to easily target ways to improve NO3- uptake. Based on this there is an identified need to better understand the NO3- uptake system and the signalling molecules that modulate it. With strong transcriptional control governing the NO3- uptake system, we also need new leads for modulating transcription of NO3- transporter genes.
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The Effectiveness of Trimetazidine Treatment in Patients with Stable Angina Pectoris of Various Durations: Results from the CHOICE-2 Study.
Glezer, M, ,
Advances in therapy. 2018;(7):1103-1113
Abstract
INTRODUCTION Trimetazidine (TMZ) has been shown to reduce angina symptoms and to increase exercise capacity in randomized clinical trials, but more extensive data would be useful to assess its effects in real-world clinical practice and in patients with different durations of disease. METHODS CHOICE-2 was a Russian, multicenter, 6-month, open-label, prospective observational study that assessed the effect of adding TMZ modified release 35 mg bid to antianginal treatment in a real-world setting. The present analysis of CHOICE-2 results explored the effects of adding TMZ to background antianginal therapies with regard to the duration of stable angina. RESULTS A total of 741 patients with known durations of disease were divided into four groups according to stable angina pectoris (AP) duration, ranging from less than 1 year to more than 9 years. Addition of TMZ led to a significant decrease in the frequency of angina attacks and in the use of short-acting nitrates in all groups. In patients with recently diagnosed angina (AP duration < 1 year), the average number of angina attacks per week decreased significantly from 3.75 ± 4.63 to 0.67 ± 1.51 and in those with advanced disease (AP duration > 9 years) from 5.63 ± 5.24 to 1.32 ± 2.07. Angina-free walking distance also improved significantly. Addition of TMZ also improved patient well-being. Results were achieved rapidly (within 2 weeks), were maintained over 6 months, and were obtained in all patient groups regardless of angina duration. CONCLUSION TMZ added to other antianginal therapies proved to be effective for reducing angina attacks and short-acting nitrate use, increasing angina-free walking distance, and improving patient well-being in a real-life setting, irrespective of angina duration, including patients with recently diagnosed angina. This provides an opportunity for intensification of treatment early on in the disease process, with the aim of decreasing angina burden and improving patient quality of life. FUNDING Servier. TRIAL REGISTRATION ISRCTN identifier ISRCTN65209863. Plain language summary available for this article.
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Nitrate Transport, Signaling, and Use Efficiency.
Wang, YY, Cheng, YH, Chen, KE, Tsay, YF
Annual review of plant biology. 2018;:85-122
Abstract
Nitrogen accounts for approximately 60% of the fertilizer consumed each year; thus, it represents one of the major input costs for most nonlegume crops. Nitrate is one of the two major forms of nitrogen that plants acquire from the soil. Mechanistic insights into nitrate transport and signaling have enabled new strategies for enhancing nitrogen utilization efficiency, for lowering input costs for farming, and, more importantly, for alleviating environmental impacts (e.g., eutrophication and production of the greenhouse gas N2O). Over the past decade, significant progress has been made in understanding how nitrate is acquired from the surroundings, how it is efficiently distributed into different plant tissues in response to environmental changes, how nitrate signaling is perceived and transmitted, and how shoot and root nitrogen status is communicated. Several key components of these processes have proven to be novel tools for enhancing nitrate- and nitrogen-use efficiency. In this review, we focus on the roles of NRT1 and NRT2 in nitrate uptake and nitrate allocation among different tissues; we describe the functions of the transceptor NRT1.1, transcription factors, and small signaling peptides in nitrate signaling and tissue communication; and we compile the new strategies for improving nitrogen-use efficiency.
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The S-Type Anion Channel ZmSLAC1 Plays Essential Roles in Stomatal Closure by Mediating Nitrate Efflux in Maize.
Qi, GN, Yao, FY, Ren, HM, Sun, SJ, Tan, YQ, Zhang, ZC, Qiu, BS, Wang, YF
Plant & cell physiology. 2018;(3):614-623
Abstract
Diverse stimuli induce stomatal closure by triggering the efflux of osmotic anions, which is mainly mediated by the main anion channel SLAC1 in plants, and the anion permeability and selectivity of SLAC1 channels from several plant species have been reported to be variable. However, the genetic identity as well as the anion permeability and selectivity of the main S-type anion channel ZmSLAC1 in maize are still unknown. In this study, we identified GRMZM2G106921 as the gene encoding ZmSLAC1 in maize, and the maize mutants zmslac1-1 and zmslac1-2 harboring a mutator (Mu) transposon in ZmSLAC1 exhibited strong insensitive phenotypes of stomatal closure in response to diverse stimuli. We further found that ZmSLAC1 functions as a nitrate-selective anion channel without obvious permeability to chloride, sulfate and malate, clearly different from SLAC1 channels of Arabidopsis thaliana, Brassica rapa ssp. chinensis and Solanum lycopersicum L. Further experimental data show that the expression of ZmSLAC1 successfully rescued the stomatal movement phenotypes of the Arabidopsis double mutant atslac1-3atslah3-2 by mainly restoring nitrate-carried anion channel currents of guard cells. Together, these findings demonstrate that ZmSLAC1 is involved in stomatal closure mainly by mediating the efflux of nitrate in maize.
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Vegetable-derived bioactive nitrate and cardiovascular health.
Bondonno, CP, Blekkenhorst, LC, Liu, AH, Bondonno, NP, Ward, NC, Croft, KD, Hodgson, JM
Molecular aspects of medicine. 2018;:83-91
Abstract
Vegetable derived nitrate is now recognised as an important bioactive phytochemical with cardioprotective properties. Nitrate, through the recently described enterosalivary nitrate-nitrite-nitric oxide (NO) pathway, increases NO, a molecule pivotal for cardiovascular health. Clinical trials have observed that dietary nitrate has similar effects to NO when supplied exogenously. These effects include reduced blood pressure and improvements in other markers of vascular health such as endothelial function, arterial stiffness, ischemia reperfusion injury, blood flow, and platelet aggregation. Few observational studies, however, have examined dietary nitrate intake and long term cardiovascular health outcomes. This represents a significant gap in the literature. There is also a lingering concern about a possible carcinogenic effect of nitrate intake. Additionally, a number of potential factors that could impact nitrate to nitrite to NO reduction have been identified. This review will provide an overview of the evidence to date that nitrate, through its effects on endogenous NO and vascular health, is an important bioactive cardioprotective component of a diet rich in vegetables.