Inorganic Nitrate Metabolism Within The Human Body: Dietary Nitrate Supplementation and Factors Influencing NO Bioavailability

The use of nitrate (NO3-) as a dietary supplement to augment health and improve exercise performance has gained considerable attention in the last decade, with substantial evidence supporting its efficacy as a therapeutic and ergogenic aid. Importantly, the documented benefits have primarily been attributed to changes in nitric oxide (NO) bioavailability throughout the body. Pathways related to NO metabolism have been extensively studied. However, emerging evidence provides novel insights into how the efficacy of dietary NO3- supplementation may be contingent on additional components such as the oral microbiome and biological tissues (i.e. skin and skeletal muscle). Evidence supporting beneficial effects of dietary NO3- ingestion on indices of cardiovascular and metabolic health, as well as on the physiological responses to exercise is abundant. Nonetheless, certain clinical conditions in which the composition and environment within the mouth may be altered such as with oral disease, diabetes, pulmonary hypertension, obesity, cardiovascular disease (Koch et al. 2017), as well as the use of anti-bacterial mouthwash, may limit the body’s ability to sequester NO3- from foodstuffs. In an attempt to circumvent the role of the oral microbiome in NO3- metabolism, chapter 5 investigated whether using a NO3- containing skin lotion could be employed to alter circulating NO3- and NO2-, a marker of NO bioavailability. Results from this chapter illustrated that in humans, NO3- does not appear to traverse through skin to reach the circulation and is ineffective at changing circulating NO3- and NO2-. It is therefore unlikely to influence NO3- metabolism or evoke physiological responses. Chapter 6 highlights the role of habitual NO3- ingestion (or lack thereof) on the microbial profile in the oral cavity. It was found that when human volunteers were deprived of dietary NO3- (30 – 50 mg NO3-), salivary [NO3-] and [NO2-] decreased when compared to the ingestion of a diet containing a standard (180 mg NO3-) or a high (1000 mg NO3-) NO3- content. Furthermore, exploratory analyses demonstrated that the alterations in the prevalence (relative abundance of OTUs) of certain bacterial genera and species began to occur following as little as 7-days of dietary NO3- deprivation. Chapters 7 and 8 investigated the effect of NO3- ingestion on the presence of NO3- in skeletal muscle. Chapter 7 demonstrated that, contrary to early rodent work, the elevation of NO3- in human skeletal muscle following dietary NO3- supplementation is short-lived. The profile of changes in skeletal muscle [NO3-] following the ingestion of NO3- closely reflects that seen in biological fluids such as plasma and saliva, with skeletal muscle [NO3-] initially increasing as early as 30 minutes, peaking between 1 and 3 hours and returning to baseline values at around 9 hours post NO3- ingestion. Chapter 8 is the first study to directly quantify the relative contribution of ingested NO3- to changes in [NO3-] in plasma, saliva, urine and skeletal muscle. One hour following the ingestion of a K15NO3 stable isotope tracer, labelled NO3- accounted for 68% of the total NO3- in skeletal muscle, and ~94%, 96% and 89% of total NO3- in plasma, saliva and urine, respectively. The work that comprises this thesis evidences the importance of the oral microbiome and its NO2- generating properties by illustrating the ineffectiveness of alternative means of inducing change in circulating NO3- and NO2-. This, coupled with the findings that the oral microbiome is malleable following not only increased NO3- ingestion, but also the removal of NO3- from the diet, substantiates the importance of NO3- ingestion for NO metabolism. Furthermore, this thesis indicates that biological tissues are likely an integral component which influence NO- related processes and therefore should be considered when discussing the effect of NO3- ingestion. This is due to the findings that, following NO3- consumption, the circulation and distribution of NO3- is prompt and substantial increases of NO-related metabolites can be detected in biological fluids (i.e. saliva, whole blood, red blood cells, plasma) and tissues (i.e. skeletal muscle) simultaneously.This thesis was jointly supervised and awarded by the University of Exeter and the University of Queenslan

Discrete physiological effects of beetroot juice and potassium nitrate supplementation following 4-wk sprint interval training

This is the author accepted manuscript. The final version is available from the American Physiological Society via the DOI in this record.The physiological and exercise performance adaptations to sprint interval training (SIT) may be modified by dietary nitrate (NO3) supplementation. However, it is possible that different types of NO3 supplementation evoke divergent physiological and performance adaptations to SIT. The purpose of this study was to compare the effects of 4-wk SIT with and without concurrent dietary NO3 supplementation administered as either NO3-rich beetroot juice (BR) or potassium NO3 (KNO3). Thirty recreationally active subjects completed a battery of exercise tests before and after a 4-wk intervention in which they were allocated to one of three groups: 1) SIT undertaken without dietary NO3 supplementation (SIT); 2) SIT accompanied by concurrent BR supplementation (SIT BR); or 3) SIT accompanied by concurrent KNO3 supplementation (SIT KNO3). During severe-intensity exercise, V O2peak and time to task failure were improved to a greater extent with SIT +BR than SIT and SIT KNO3 (P 0.05). There was also a greater reduction in the accumulation of muscle lactate at 3 min of severe-intensity exercise in SIT BR compared with SIT KNO3 (P <0.05). Plasma NO2 concentration fell to a greater extent during severe-intensity exercise in SIT BR compared with SIT and SIT KNO3 (P <0.05). There were no differences between groups in the reduction in the muscle phosphocreatine recovery time constant from pre- to postintervention (P <0.05). These findings indicate that 4-wk SIT with concurrent BR supplementation results in greater exercise capacity adaptations compared with SIT alone and SIT with concurrent KNO3 supplementation. This may be the result of greater NO-mediated signaling in SIT +BR compared with SIT+ KNO3. NEW & NOTEWORTHY We compared the influence of different forms of dietary nitrate supplementation on the physiological and performance adaptations to sprint interval training (SIT). Compared with SIT alone, supplementation with nitrate-rich beetroot juice, but not potassium NO3, enhanced some physiological adaptations to training

Human skeletal muscle nitrate store: influence of dietary nitrate supplementation and exercise

This is the final version. Available on open access from Wiley via the DOI in this recordRodent skeletal muscle contains a large store of nitrate that can be augmented by the consumption of dietary nitrate. This muscle nitrate reservoir has been found to be an important source of nitrite and nitric oxide (NO), via its reduction by tissue xanthine oxidoreductases (XOR). To explore if this pathway is also active in human skeletal muscle during exercise, and if it is sensitive to local nitrate availability, we assessed exercise-induced changes in muscle nitrate and nitrite concentrations in young healthy humans, under baseline conditions and following dietary nitrate consumption. We found that baseline nitrate and nitrite concentrations were far higher in muscle than in plasma (∼4-fold and ∼29-fold, respectively), and that the consumption of a single bolus of dietary nitrate (12.8 mmol) significantly elevated nitrate concentration in both plasma (∼19 fold) and muscle (∼5 fold). Consistent with these observations, and with previous suggestions of active muscle nitrate transport, we present Western blot data to show significant expression of the active nitrate/nitrite transporter, sialin, in human skeletal muscle. Furthermore, we report an exercise-induced reduction in human muscle nitrate concentration (by ∼39%), but only in the presence of an increased muscle nitrate store. Our results indicate that human skeletal muscle nitrate stores are sensitive to dietary nitrate intake and may contribute to NO generation during exercise. Together, these findings suggest that skeletal muscle plays an important role in the transport, storage and metabolism of nitrate in humans. This article is protected by copyright. All rights reserved

Development of radial-shear rolling mill special stands for continuous cast billets deformation

The article offers the structure of the three-roll stand for radial-shear rolling that is designed to deformation of continuous cast billets. The stand can be installed in the pipe rolling mill manufacturing line that shall ensure manufacturing flexibility. To achieve the objective set, elaboration of working rolls integration with the drive as well as verification against the allowable torque and strength calculations in SolidWorks Simulation were performed at the design stage. For the major part of the frame, stresses do not exceed 60 MPa and the design rigidity rate will be 2.86 MN/mm. The special stand has a specific frame structure to ensure its mounting on the existing equipment base. The configuration of rolls sets is selected considering the possibility of integration with the spindle assemblies of the group drive and maximum allowable cross angle (≤ 15 ). The developed design proves to have sufficient strength margin with the relatively small weight. The special radial-shear rolling mill stand will allow increasing total strain degree and reducing the number of billets sizes. © Published under licence by IOP Publishing Ltd

Relationships between nitric oxide biomarkers and physiological outcomes following dietary nitrate supplementation

This is the final version. Available on open access from Elsevier via the DOI in this recordData availability: Data will be made available on request.Dietary nitrate (NO3-) supplementation can increase nitric oxide (NO) bioavailability, reduce blood pressure (BP) and improve muscle contractile function in humans. Plasma nitrite concentration (plasma [NO2-]) is the most oft-used biomarker of NO bioavailability. However, it is unclear which of several NO biomarkers (NO3-, NO2-, S-nitrosothiols (RSNOs)) in plasma, whole blood (WB), red blood cells (RBC) and skeletal muscle correlate with the physiological effects of acute and chronic dietary NO3- supplementation. Using a randomized, double-blind, crossover design, 12 participants (9 males) consumed NO3--rich beetroot juice (BR) (∼12.8 mmol NO3-) and NO3--depleted placebo beetroot juice (PL) acutely and then chronically (for two weeks). Biological samples were collected, resting BP was assessed, and 10 maximal voluntary isometric contractions of the knee extensors were performed at 2.5-3.5 hours following supplement ingestion on day 1 and day 14. Diastolic BP was significantly lower in BR (-2 ± 3 mmHg, P=0.03) compared to PL following acute supplementation, while the absolute rate of torque development (RTD) was significantly greater in BR at 0-30 ms (39 ± 57 N.m.s-1, P=0.03) and 0-50 ms (79 ± 99 N.m.s-1, P=0.02) compared to PL following two weeks supplementation. Greater WB [RSNOs] rather than plasma [NO2-] was correlated with lower diastolic BP (r=-0.68, P=0.02) in BR compared to PL following acute supplementation, while greater skeletal muscle [NO3-] was correlated with greater RTD at 0-30 ms (r=0.64, P=0.03) in BR compared to PL following chronic supplementation. We conclude that [RSNOs] in blood, and [NO3-] in skeletal muscle, are relevant biomarkers of NO bioavailability which are related to the reduction of BP and the enhanced muscle contractile function following dietary NO3- ingestion in humans

Reduction in blood pressure following acute dietary nitrate ingestion is correlated with increased red blood cell S-nitrosothiol concentrations.

This is the final version. Available from Elsevier via the DOI in this record. Data availability: Data will be made available on request.Dietary nitrate (NO3-) supplementation can enhance nitric oxide (NO) bioavailability and lower blood pressure (BP) in humans. The nitrite concentration ([NO2-]) in the plasma is the most commonly used biomarker of increased NO availability. However, it is unknown to what extent changes in other NO congeners, such as S-nitrosothiols (RSNOs), and in other blood components, such as red blood cells (RBC), also contribute to the BP lowering effects of dietary NO3-. We investigated the correlations between changes in NO biomarkers in different blood compartments and changes in BP variables following acute NO3- ingestion. Resting BP was measured and blood samples were collected at baseline, and at 1, 2, 3, 4 and 24 h following acute beetroot juice (∼12.8 mmol NO3-, ∼11 mg NO3-/kg) ingestion in 20 healthy volunteers. Spearman rank correlation coefficients were determined between the peak individual increases in NO biomarkers (NO3-, NO2-, RSNOs) in plasma, RBC and whole blood, and corresponding decreases in resting BP variables. No significant correlation was observed between increased plasma [NO2-] and reduced BP, but increased RBC [NO2-] was correlated with decreased systolic BP (rs = -0.50, P = 0.03). Notably, increased RBC [RSNOs] was significantly correlated with decreases in systolic (rs = -0.68, P = 0.001), diastolic (rs = -0.59, P = 0.008) and mean arterial pressure (rs = -0.64, P = 0.003). Fisher's z transformation indicated no difference in the strength of the correlations between increases in RBC [NO2-] or [RSNOs] and decreased systolic blood pressure. In conclusion, increased RBC [RSNOs] may be an important mediator of the reduction in resting BP observed following dietary NO3- supplementation.University of ExeterChina Scholarship Counci

Изучение влияния режимов радиально-сдвиговой прокатки на температурно-деформационные условия процесса обработки алюминия АД0

The effect of deformation modes on the process conditions of radial-shear rolling (RSR) of commercial purity aluminum AA1050 is analyzed. Based on finite-element modeling (FEM), temperature variation at various feed angles and elongation in the first and last passes is obtained. An increase in the feed angle slightly raises temperature fluctuations in the surface layer due to increasing reduction per pass, but it does not significantly influence the total deformation heating during RSR. The final deformation temperature can be controlled by varying the reduction ratio. In this case, it is necessary to take into account the initial heating temperature, dimensions of final rolled products and elongation per pass. The billet size has a significant effect on thermal variations during RSR. In the last pass, when diameters are 20–14 mm, deformation heating is almost completely compensated by rod cooling in contact with the environment and the tool and begins to prevail with an increase in the elongation ratio of more than 1.2. The analysis of equivalent strain (εe) at various deformation modes showed that the difference in εe values over the rod cross-section decreases with the increasing feed angle. A comparison of the data obtained with the hardness and microstructure of rolled AA1050 samples shows that εe has a significant effect on changes in the structure and properties to a certain value. This is confirmed by the obtained microhardness distribution over the cross section of rods. Mechanical properties of obtained rods correspond to the properties of commercial purity aluminum in the work hardened condition (σв ~ 115 MPa, σ0.2 ~ 110 MPa, δ ~ 1 %, HV ~ 40÷43).Проведен анализ влияния режимов деформации на условия процесса радиально-сдвиговой прокатки (РСП) алюминия технической чистоты АД0. На основе моделирования методом конечных элементов (МКЭ) получено изменение температуры при различных углах подачи и вытяжках в первом и последнем проходах. Увеличение угла подачи незначительно повышает колебания температуры в поверхностном слое за счет роста частного обжатия, но несущественно влияет на общий деформационный разогрев в процессе РСП. Температуру окончания деформации возможно контролировать с помощью варьирования степени обжатия. При этом необходимо учитывать исходную температуру нагрева, размеры получаемого конечного проката и вытяжку за проход. Размер заготовки оказывает существенное влияние на тепловые изменения в процессе РСП. В последнем проходе, когда диаметральные размеры составляют 20–14 мм, деформационный разогрев практически полностью компенсируется охлаждением прутка при контакте с окружающей средой и инструментом и начинает преобладать с повышением коэффициента вытяжки больше 1,2. Анализ накопленной степени деформации (εн) при различных режимах деформации показал, что разница значений εн по поперечному сечению прутка уменьшается при увеличении угла подачи. Сопоставление полученных данных с твердостью и микроструктурой прокатанных образцов АД0 показывает, что величина εн оказывает значительное влияние на изменение структуры и свойств до определенного значения, что подтверждается полученным распределением микротвердости по поперечному сечению прутков. Механические свойства полученных прутков соответствуют свойствам алюминия технической чистоты в нагартованном состоянии (σв ~ 115 МПа, σ0,2 ~ 110 МПа, δ ~ 1 %, HV ~ 40÷43)

Institutional investors, climate disclosure, and carbon emissions

Exploiting the unique features of the CDP, the world-leading platform of corporate climate risk disclosures, we study the relationship between institutional investors' demand for climate-related information (as reflected in their CDP signatory status), firms' decision to disclose this information, and corporate carbon emissions. We provide systematic international evidence that ownership by CDP signatories is positively associated with the probability of disclosing information to the CDP, and that such disclosure is associated with subsequent lower carbon emissions. We also observe that CDP signatories are more likely to engage with and divest from top emitters disclosing to the CDP. Overall, these results are consistent with the notion that investor demand for climate-related information results in greater corporate disclosure and contributes to firms’ decisions to lower future carbon emissions