ABSTRACT
The Salt Substitute and Stroke Study (SSaSS) demonstrated significant reductions in systolic blood pressure (SBP), and the risk of stroke, major cardiovascular events and total mortality with the use of potassium-enriched salt. The contribution of sodium reduction versus potassium increase to these effects is unknown. We identified four different data sources describing the association between sodium reduction, potassium supplementation and change in SBP. We then fitted a series of models to estimate the SBP reductions expected for the differences in sodium and potassium intake in SSaSS, derived from 24-h urine collections. The proportions of the SBP reduction separately attributable to sodium reduction and potassium supplementation were calculated. The observed SBP reduction in SSaSS was -3.3 mmHg with a corresponding mean 15.2 mmol reduction in 24-h sodium excretion and a mean 20.6 mmol increase in 24-h potassium excretion. Assuming 90% of dietary sodium intake and 70% of dietary potassium intake were excreted through urine, the models projected falls in SBP of between -1.67 (95% confidence interval: -4.06 to +0.73) mmHg and -5.33 (95% confidence interval: -8.58 to -2.08) mmHg. The estimated proportional contribution of sodium reduction to the SBP fall ranged between 12 and 39% for the different models fitted. Sensitivity analyses assuming different proportional urinary excretion of dietary sodium and potassium intake showed similar results. In every model, the majority of the SBP lowering effect in SSaSS was estimated to be attributable to the increase in dietary potassium rather than the fall in dietary sodium.
Subject(s)
Hypertension , Hypotension , Sodium Radioisotopes , Sodium, Dietary , Stroke , Humans , Blood Pressure/physiology , Potassium/urine , Potassium, Dietary , Sodium/urine , Sodium, Dietary/adverse effects , Sodium Chloride, Dietary/adverse effects , Stroke/prevention & controlABSTRACT
Patients with treatment resistant hypertension (TRH) are known to have elevated sodium (Na) content in muscle and skin. Renal denervation (RDN) emerged as an adjacent therapeutic option in this group of patients. This analysis aimed at evaluating whether tissue Na content predicts blood pressure (BP) response after RDN in patients with TRH. Radiofrequency-device based RDN was performed in 58 patients with uncontrolled TRH. Office and 24-h ambulatory BP were measured at baseline and after 6 months. To assess tissue Na content Na magnetic resonance imaging (Na-MRI) was performed at baseline prior to RDN. We splitted the study cohort into responders and non-responders based on the median of systolic 24-h ambulatory blood pressure (ABP) reduction after 6 months and evaluated the association between BP response to RDN and tissue Na content in skin and muscle. The study was registered at http://www.clinicaltrials.gov (NCT01687725). Six months after RDN 24-h ABP decreased by -8.6/-4.7 mmHg. BP-Responders were characterized by the following parameters: low tissue sodium content in the skin (p = 0.040), female gender (p = 0.027), intake of aldosterone antagonists (p = 0.032), high baseline 24-h night-time heart rate (p = 0.045) and high LDL cholesterol (p < 0.001). These results remained significant after adjustment for baseline 24-h systolic BP. Similar results were obtained when the median of day-time and night-time ABP reduction after 6 months were used as cut-off criteria for defining BP response to RDN. We conclude that in addition to clinical factors including baseline 24-h ABP Na-MRI may assist to select patients with uncontrolled TRH for RDN treatment.
Subject(s)
Hypertension , Hypotension , Sodium Radioisotopes , Female , Humans , Antihypertensive Agents/pharmacology , Blood Pressure/physiology , Blood Pressure Monitoring, Ambulatory , Denervation , Kidney/diagnostic imaging , Sodium , Sympathectomy/methods , Treatment Outcome , Male , Clinical Trials as TopicABSTRACT
Accurate estimation of sodium intake is a key requirement for evaluating the efficacy of interventional strategies to reduce salt intake. The effectiveness of a smartphone application in measuring dietary sodium intake was assessed. This study included 46 participants who consented to register in Noom's food-logging program. All participants were followed up for six months from the day of enrollment. The mean age of the participants was 40.2 ± 12.3 years, and 22 (48%) participants were male. The average number of times/weeks the meals were logged was 16.2 ± 10.3. At baseline, the mean 24-h urine sodium was 124.3 mmol/24 h. The mean sodium intake measured by the smartphone application and calculated using the 24-h urine sodium was 2020.9 mg/24 h and 2857.6 mg/24 h, respectively. During the second visit, the mean 24-h urine sodium was 117.4 mmol/24 h. The mean sodium intake measured by the smartphone application and calculated using the 24-h urine sodium was 1456.0 mg/24 h and 2698.3 mg/24 h, respectively. Sodium intake measured using the smartphone application positively correlated with that calculated using the 24-h urine sodium at baseline (r = 0.464; p < 0.001) and follow-up (r = 0.334; p= 0.023). Dietary sodium intake measured using a smartphone application correlated well with that estimated using 24-h urine sodium level.
Subject(s)
Smartphone , Sodium, Dietary , Humans , Male , Adult , Middle Aged , Female , Nutritional Status , Meals , Sodium RadioisotopesABSTRACT
This cross-sectional study aimed to estimate the daily salt intake of medical professionals working in public health facilities in Darkhan-Uul Province, Mongolia. We conducted a multiple logistic regression analysis to identify factors associated with their consumption of salt exceeding the recommended daily salt intake (≥ 5 g/day). A self-administered questionnaire and 24-h urine samples were used to obtain data on the participants' salt intake. Of 338 participants, 159 completed the 24-h urine collection. The mean sodium excretion into urine was 122.3 mmol/day, which was equivalent to a mean salt intake of 7.7 g/day when the urinary excretion rate was considered as 93%. Body mass index was positively correlated with excess salt intake (adjusted odds ratio [AOR]: 1.27; 95% confidence interval [CI] 1.10-1.46), while age was negatively correlated with excess salt intake (AOR: 0.95; 95% CI 0.91-1.00). Participants who consumed ≥ 2 cups of salted suutei tsai (Mongolian milk tea) daily had a higher risk of consuming ≥ 5 g/day of salt than those who consumed ≤ 1 cup/day. The average estimated salt intake of the participants was higher than the recommended value. Medical professionals should be aware of factors associated with excessive salt consumption and make appropriate adjustments to minimize it.
Subject(s)
Body Fluids , Sodium Chloride, Dietary , Humans , Animals , Cross-Sectional Studies , Mongolia , Sodium Radioisotopes , Sodium Chloride , GerbillinaeABSTRACT
OBJECTIVES: High sodium intake is strongly associated with hypertension and obesity. This study aims to investigate the relationship between 24-h urinary sodium (a surrogate measure of sodium intake), ambulatory blood pressure parameters, left atrial function, and left atrioventricular coupling. Further, we intend to examine whether blood pressure and BMI might be mediators of the relationship between 24-h urinary sodium and subclinical cardiac function. METHODS: Our study had 398 participants, all of whom were subjected to 24-h urine collection, 24-h ambulatory blood pressure measurement, and cardiac magnetic resonance imaging. RESULTS: The average age of the participants was 55.70â±â11.30âyears old. The mean urinary sodium of the participants was 172.01â±â80.24âmmol/24âh. After adjusting for age, sex, history of diabetes, smoking status, alcohol consumption, and use of diuretics, 24-h urinary sodium was correlated with multiple ambulatory blood pressure parameters, BMI, left atrial function, and the left atrioventricular coupling index (LACI) (Pâ<â0.05). Mediation analysis showed that BMI explained 16% of the indirect effect of 24-h urinary sodium and left atrial function and 30% of the indirect effect of LACI. Independent of the mediator, 24-h urinary sodium had a significant direct effect on left atrial function and left atrioventricular coupling. CONCLUSIONS: Higher 24-h urinary sodium was associated with a greater BMI as well as poor left atrial function and left atrioventricular coupling, and the BMI mediated the relationship between 24-h urinary sodium and subclinical left cardiac function. Furthermore, and more importantly, 24-h urinary sodium may have directly affected the left atrial function and left atrioventricular coupling independent of intermediary factors.
Subject(s)
Atrial Function, Left , Sodium, Dietary , Humans , Adult , Middle Aged , Aged , Blood Pressure Monitoring, Ambulatory , Sodium Radioisotopes , ChinaABSTRACT
Objective: The relationship between sodium intake and cardiovascular (CV) events remains unconfirmed. Therefore, we carried out a systematic review and dose-response meta-analysis for evaluating the potential impact of 24-hour sodium excretion on CV risk. Besides, 24-hour sodium excretion was used to replace daily sodium diet intake. Methods: We searched ISI Web of Science, Embase, PubMed, and the Cochrane Library. Our study included cohort studies reporting hazard ratio ( HR). The random-effects model was used for summarizing the total relative risks ( RRs) between the included studies. In addition, the generalized least-squares regression was employed to fit the study model. Results: A total of 9 studies involving 645,006 participants were included in this study. A significant non-linear relationship was observed between sodium excretion and CV events ( P non-linearity < 0.001). In studies collecting 24-h urine samples, the sodium excretion and CV events risk were associated linearly ( RR: 1.04; 95% CI: 1.01, 1.07). Conclusion: In a linear dose-response manner, every 1 g increase in sodium intake was associated with an increased risk of CV events up to 4%. Further studies are required to validate our conclusions further.
Subject(s)
Cardiovascular Diseases , Sodium, Dietary , Humans , Urinalysis , Sodium Radioisotopes , Cardiovascular Diseases/epidemiology , Sodium, Dietary/adverse effectsABSTRACT
Spot urine specimens have been used to estimate 24 h urinary sodium (Na) excretion (24UNaV) and potassium (K) excretion (24UKV). However, the validity is limited for 24UNaV and unknown for 24UKV in stroke patients, using the existing formulas. Herein, we developed and validated a new formula for 24UNaV and 24UKV by spot urine specimens in stroke patients. Spot and 24 h urine samples were collected from 970 stroke patients. The models of 24UNaV and 24UKV were developed using stepwise multivariate linear regression in 689 patients. The performance of different formulas was internally validated in 281 patients at the population and individual levels. The obtained new formulas were: (1) estimated 24UNaV (mmol/day): -0.191 × Age + 4.349 × BMI + 0.229 × SpotNa + 1.744 × SpotNa/Spot creatinine (Cr) + 41.492 (for male); -1.030 × Age + 2.011 × BMI + 0.143 × SpotNa + 1.035 × SpotNa/SpotCr + 147.159 (for female); and (2) estimated 24UKV (mmol/day): -0.052 × Age + 0.410 × BMI + 0.031 × SpotK + 33.280 × Ln (spotK/spot Cr) - 5.789 × Ln (spotNa/spot Cr) - 1.035 (for male); -0.235 × Age + 0.530 × BMI + 0.040 × SpotK + 30.990 × Ln (spot K/spot Cr) - 7.837 × Ln (spotNa/spotCr) + 4.318 (for female). The new formula obtained the lowest mean bias (5.17 mmol/day for 24UNaV and 0.85 mmol/day for 24UKV) and highest proportion at the cutoff under the ±30% level for the estimation of 24UNaV (59.43%) and 24UKV (70.11%). The new formula provides a meaningful exploration to estimate 24UNaV and 24UKV in stroke patients by using spot urine specimens.
Subject(s)
Potassium , Stroke , Child, Preschool , Creatinine/urine , Female , Humans , Infant , Male , Potassium/urine , Sodium/urine , Sodium Radioisotopes , Urinalysis/methods , Urine Specimen Collection/methodsABSTRACT
BACKGROUND & AIMS: Dietary sodium restriction is recommended by current guidelines to reduce blood pressure and decrease the risk of cardiovascular disease. Current methods to assess sodium intake such as dietary questionnaires and 24-h urine collection are cumbersome, and the results are not readily available to patients. In this analysis, we evaluated using chloride and creatinine dipsticks as a convenient method to monitor sodium intake, in addition to patients' ability to practice this method independently. METHODS: This is a post-hoc analysis of a previously published trial, LowSalt4Life, that measured change in sodium consumption over 8 weeks to evaluate the effect of a just-in-time adaptive mobile application intervention. Participants were instructed on how to complete and interpret Quantab® chloride and Multistix® PRO 10 LS creatinine dipstick measurements at home and upload a picture of their results. A pharmacy student interpreted the chloride dipsticks, and intraclass correlation coefficients (ICC) were calculated to assess interrater reliability between the participant and pharmacy student. Predicted 24-h sodium values were calculated by the Kawasaki and Mann methods and compared to actual 24-h sodium excretion. RESULTS: There was a strong interobserver correlation between interpretations of the chloride dipsticks, with the ICC values 0.90, 0.97, 0.99, and 0.98 at weeks 2, 4, 6, and 8, respectively. There was a moderate correlation between the dipstick predicted 24-h sodium excretion and actual 24-h sodium excretion at baseline (r = 0.506; P < 0.001), and a weak correlation at week 8 (r = 0.187; P = 0.217). When corrected creatinine values were used, the dipstick predicted 24-h sodium excretion correlated with the actual 24-h sodium excretion at baseline and week 8 (r = 0.512; P < 0.001 and r = 0.451; P = 0.002). CONCLUSIONS: Our analysis suggests that chloride and creatinine dipsticks have the potential to predict total daily excretion of sodium. This method provides patients with an easy, convenient, and accurate method to assess sodium excretion at home. Further research is needed to identify the optimal timing of performing the dipstick analysis as well as ways to improve the creatinine measurement of the urine samples. TRIAL REGISTRATION: ClinicalTrials.gov NCT03099343; https://clinicaltrials.gov/ct2/show/NCT03099343.
Subject(s)
Hypertension , Sodium, Dietary , Chlorides , Creatinine , Humans , Hypertension/diagnosis , Reproducibility of Results , Self-Assessment , Sodium/urine , Sodium RadioisotopesABSTRACT
No disponible
Subject(s)
Humans , Female , Middle Aged , Bone Neoplasms/diagnostic imaging , Fluorodeoxyglucose F18 , Osteoma, Osteoid/diagnostic imaging , Parietal Bone/diagnostic imaging , Tomography, X-Ray Computed , Radiopharmaceuticals , Ribs/diagnostic imaging , Positron-Emission Tomography , Skull Neoplasms/diagnostic imaging , Sodium Fluoride , Sodium RadioisotopesABSTRACT
Positron emission tomography (PET) with 18F-sodium fluoride (18F-NaF) has emerged as a promising non-invasive imaging modality to identify high-risk and ruptured atherosclerotic plaques. By visualizing microcalcification, 18F-NaF PET holds clinical promise in refining how we evaluate coronary artery disease, shifting our focus from assessing disease burden to atherosclerosis activity. In this review, we provide an overview of studies that have utilized 18F-NaF PET for imaging atherosclerosis. We discuss the associations between traditional coronary artery disease measures (risk factors) and 18F-NaF plaque activity. We also present the data on the histological validation as well as show how 18F-NaF uptake is associated with plaque morphology on intravascular and CT imaging. Finally, we discuss the technical challenges associated with 18F-NaF coronary PET highlighting recent advances in this area.
Subject(s)
Coronary Artery Disease/diagnostic imaging , Fluorine Radioisotopes , Plaque, Atherosclerotic/diagnostic imaging , Positron-Emission Tomography/methods , Radiopharmaceuticals , Sodium Radioisotopes , Vascular Calcification/diagnostic imaging , Computed Tomography Angiography , Coronary Artery Disease/metabolism , Fluorine Radioisotopes/pharmacokinetics , Humans , Movement , Organ Motion , Plaque, Atherosclerotic/metabolism , Positron Emission Tomography Computed Tomography , Radiopharmaceuticals/pharmacokinetics , Risk Factors , Sodium Fluoride/pharmacokinetics , Sodium Radioisotopes/pharmacokinetics , Vascular Calcification/metabolismSubject(s)
Bone Neoplasms/diagnostic imaging , Fluorodeoxyglucose F18 , Osteoma, Osteoid/diagnostic imaging , Parietal Bone/diagnostic imaging , Positron Emission Tomography Computed Tomography , Radiopharmaceuticals , Ribs/diagnostic imaging , Sodium Fluoride , Female , Humans , Middle Aged , Skull Neoplasms/diagnostic imaging , Sodium RadioisotopesABSTRACT
The unique feature of nuclear accidents with neutron exposure is the induced radioactivity in body tissues. For dosimetry purposes, the most important stable isotopes occurring in human body, which can be activated by neutrons, are 23 Na and 32 S. The respective activation reactions are as follows:23Na(n,γ)24Na and32S(n,p)32P. While sodium occurs in human blood, sulfur is present in human hair. In order to verify the practical feasibility of this dosimetry technique in conditions of our laboratory, samples of human blood and hair were irradiated in a channel of a training reactor VR-1.24Na activity was measured by gamma-ray spectrometry.32P activity in hair was measured by means of a proportional counter. Based on neutron-spectrum calculation, relationships between neutron dose and induced activity were derived for both blood and hair.
Subject(s)
Blood/radiation effects , Hair/radiation effects , Neutrons , Phosphorus Radioisotopes/analysis , Radiometry/methods , Sodium/analysis , Sulfur/analysis , Czech Republic , Gamma Rays , Humans , Radiation Dosage , Radioactive Hazard Release , Radioactivity , Sodium RadioisotopesABSTRACT
The action of free radicals is believed responsible for much or most biological injury resulting from exposure to ionizing radiation. These molecules in solution possess short lifetimes on the order of nanoseconds to microseconds. As a result, the dose-which measures the energy dissipated in tissue due to radiolysis-should not be considered a reliable indicator of the free radical concentration, nor of the chemical effects that follow from it. Rather, the chemical state of affected tissue is properly represented only by the dissipated power, which describes the distribution of energy with time. The present report demonstrates the validity of this assertion using data contained in a report describing a benchtop experiment published in 1972. The experiment used the visible rupture of a model phospholipid membrane as a means to quantify the degree of chemical insult caused by ionizing radiation. The experiment found that beta doses in the range from 1-10 rad were equivalent to x-ray rupture doses of 3,500 rad. This report demonstrates that the experimental results are convincingly explained by reference to the properly calculated time-averaged dissipated power due to beta decay. The theoretical explanation is derived by analogy to a well-understood result from electronic systems known as shot noise. If the result described in this report is demonstrated to extrapolate from the benchtop to living systems, then it is likely that exposure to beta radiation via internal incorporation is far more hazardous than commonly believed. The finding could be revolutionary in the field of health physics.
Subject(s)
Membranes/physiology , Models, Theoretical , Phospholipids/chemistry , Radiometry/instrumentation , Sodium Radioisotopes/adverse effects , Dose-Response Relationship, Radiation , Humans , Membranes/radiation effects , Signal-To-Noise Ratio , X-RaysABSTRACT
Cosmogenic radionuclides provide information about air masses exchanges between stratosphere and troposphere. The 7Be concentration in aerosols usually shows a seasonal variability, depending also of the climatic conditions. There are, however, fewer data available of the behavior of other cosmogenic radionuclides, such as 10Be and 22Na. In this work about 7 years of aerosols collected in Cáceres (Spain) were analyzed. The 7Be concentration was higher than 22Na and 10Be, being the 22Na/7Be and 10Be/7Be ratios (1.16⯱â¯0.02)·10-4 and (1.5⯱â¯0.3)·10-4 respectively. For the 22Na/7Be, a seasonal variation was observed, being higher in spring/summer. Seasonal variation of 7Be and 22Na were explained using a model taking into account local values of the solar radiation, rainfall and dry deposition. The effective residence time for 7Be and 22Na were (9.9⯱â¯1.0) and (11.3⯱â¯1.4) d respectively. Both 7Be and 22Na seemed to decrease with increasing number of sunspots, although it was not statistically significant probably due to the low solar activity reported in the analyzed period.
Subject(s)
Air Pollutants, Radioactive/analysis , Radiation Monitoring , Aerosols/analysis , Atmosphere/chemistry , Beryllium , Radioisotopes , Seasons , Sodium Radioisotopes/analysis , SpainABSTRACT
BACKGROUND: Due to the known contribution of excess sodium intake on elevations in blood pressure, salt reduction regulations are being introduced in countries all over the world. To study the contribution of sodium intake on cardiovascular disease development, we determined whether left ventricular mass associates with sodium excretion in young adults free from overt cardiovascular disease and those with masked hypertension. METHODS: We included 681 participants (41% men and 50% black) in a cross-sectional analysis from the African-PREDICT study with complete 24-hour urine collections and successful ambulatory blood pressure monitoring (>70% valid readings). The participants were categorized as normotensive (nâ¯=â¯534) or masked hypertensive (nâ¯=â¯147). In addition, we determined left ventricular mass index (LVMI) along with traditional risk factors. RESULTS: Masked hypertensive individuals had higher sodium excretion (149 vs. 128â¯mmol/L/day) and LVMI (78.1 vs. 69.6â¯g/m2) than normotensives. In single, partial and multiple regression analyses, LVMI independently associated with higher sodium excretion in the total group of young adults (ßâ¯=â¯0.089; pâ¯=â¯0.011). This result was also evident among masked hypertensives (ßâ¯=â¯0.215; pâ¯=â¯0.008), but not in normotensives (ßâ¯=â¯0.054; pâ¯=â¯0.134). CONCLUSION: Our results indicated that higher sodium excretion (reflecting a higher salt intake) may contribute to increased left ventricular mass, potentially driven by the early development of masked or undetected hypertension.
Subject(s)
Hypertrophy, Left Ventricular/epidemiology , Hypertrophy, Left Ventricular/urine , Masked Hypertension/epidemiology , Masked Hypertension/urine , Sodium, Dietary/urine , Adult , Africa/epidemiology , Cross-Sectional Studies , Female , Humans , Hypertrophy, Left Ventricular/diagnosis , Male , Masked Hypertension/diagnosis , Predictive Value of Tests , Prospective Studies , Sodium Radioisotopes/urine , Sodium, Dietary/adverse effects , Young AdultABSTRACT
MAIN CONCLUSION: A systematic analysis of NaCl-dependent, plasma-membrane depolarization (∆∆Ψ) in rice roots calls into question the current leading model of rapid membrane cycling of Na+ under salt stress. To investigate the character and mechanisms of Na+ influx into roots, Na+-dependent changes in plasma-membrane electrical potentials (∆∆Ψ) were measured in root cells of intact rice (Oryza sativa L., cv. Pokkali) seedlings. As external sodium concentrations ([Na+]ext) were increased in a step gradient from 0 to 100 mM, membrane potentials depolarized in a saturable manner, fitting a Michaelis-Menten model and contradicting the linear (non-saturating) models developed from radiotracer studies. Clear differences in saturation patterns were found between plants grown under low- and high-nutrient (LN and HN) conditions, with LN plants showing greater depolarization and higher affinity for Na+ (i.e., higher Vmax and lower Km) than HN plants. In addition, counterion effects on ∆∆Ψ were pronounced in LN plants (with ∆∆Ψ decreasing in the order: Cl- > SO42- > HPO 4 2- ), but not seen in HN plants. When effects of osmotic strength, Cl- influx, K+ efflux, and H+-ATPase activity on ∆∆Ψ were accounted for, resultant Km and Vmax values suggested that a single, dominant Na+-transport mechanism was operating under each nutritional condition, with Km values of 1.2 and 16 mM for LN and HN plants, respectively. Comparing saturating patterns of depolarization to linear patterns of 24Na+ radiotracer influx leads to the conclusion that electrophysiological and tracer methods do not report the same phenomena and that the current model of rapid transmembrane sodium cycling may require revision.
Subject(s)
Oryza/metabolism , Sodium/metabolism , Cell Membrane/metabolism , Chlorides/metabolism , Membrane Potentials , Osmotic Pressure , Potassium Radioisotopes/metabolism , Proton-Translocating ATPases/metabolism , Sodium Radioisotopes/metabolismABSTRACT
This article presents yearly mean concentrations of cosmogenic radionuclides 7Be and 22Na occurring in dry and wet depositions (fallout) and aerosols. Time dependencies negatively correlated with the yearly mean number of sunspots. Activity concentrations of 7Be and 22Na in aerosols in the surface air had a correlation of near-unity. 7Be in aerosols exhibited a smoother time dependence than 22Na, implying that the production of 22Na is more sensitive to the solar activity than the production of 7Be. The effect of the measured doses on the general population through internal and external exposure to radiation from cosmogenic radionuclides was small.
Subject(s)
Air Pollutants, Radioactive/analysis , Beryllium/analysis , Radiation Dosage , Radiation Monitoring/methods , Radioisotopes/analysis , Sodium Radioisotopes/analysis , Solar Activity , SloveniaABSTRACT
Using a previously developed digital gamma-gamma coincidence/anticoincidence spectrometer, daily aerosol samples collected at Resolute Bay, Canada (74.71°N, 94.97°W) from May 2016 to April 2017 were analysed for activity concentrations of 22Na and 7Be. The spectrometer design allows a more selective measurement of 22Na with a significant background reduction by gamma-gamma coincidence events processing. It has been demonstrated that the improved spectrometer provides a more sensitive and effective way to quantify trace amounts of 22Na and 7Be with a critical limit of 3 mBq and 5 Bq respectively for a 20â¯h counting. The 7Be/22Na ratio data set obtained in this study showed significant annual variation, which has a distinct spring (typically from February to May) maximum and winter (from September to February of next calendar year) minimum, which suggest that it could be used as a radiochronometer for studying the atmospheric processes. The 7Be/22Na ratios are most likely connected to deep stratosphere-to-troposphere transport (STT) exchange events where air with a higher 7Be/22Na ratio originates from downward flow from stratosphere to the troposphere. The aerosols with lower 7Be/22Na ratios located between two oscillation peaks may have longer residence time. The correlations between 7Be and 22Na activity concentration were the high during these time periods. Compared with other studies based on weekly collected aerosol samples, the techniques greatly improve the temporal resolution of 7Be/22Na data set that will be able to provide more detailed information to study various atmospheric phenomena.
Subject(s)
Air Pollutants, Radioactive/analysis , Beryllium/analysis , Radiation Monitoring , Radioisotopes/analysis , Sodium Radioisotopes/analysis , Aerosols/analysis , Atmosphere/chemistry , Bays , Canada , SeasonsABSTRACT
Sodium MRI (23Na-MRI) has been used to non-invasively quantify tissue sodium but has been limited by low spatial resolution. Here we demonstrate for the first time that high resolution 23Na-MRI reveals the spatial heterogeneity of sodium concentration within a multiple sclerosis (MS) lesion. A patient with treatment-naïve relapsing-remitting MS and a ring-enhancing lesion was imaged using 23Na-MRI. The periphery of the lesion demonstrated an elevated total sodium content compared to the normal appearing white and grey matter (p<0.01), as well as a heterogeneous distribution of both the total tissue sodium concentration and the intracellular-weighted sodium concentration.
Subject(s)
Brain/diagnostic imaging , Magnetic Resonance Imaging , Multiple Sclerosis/diagnostic imaging , Multiple Sclerosis/metabolism , Sodium/metabolism , Adult , Analysis of Variance , Brain/drug effects , Disability Evaluation , Female , Humans , Imaging, Three-Dimensional , Sodium Radioisotopes/pharmacokineticsABSTRACT
Using a recently published global data set of 22Na and 7Be from the global monitoring network of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), atmospheric circulation and stratosphere-troposphere interactions are examined. Cosmogenic 22Na has a half-life well-suited to environmental processes with durations from several months to a decade. Combined with corresponding 7Be observations, these two cosmogenic isotopes form a useful environmental tracer and new radiochronometer to study physical interactions of air masses in the stratosphere and troposphere.