Zinc Oxide Nanoparticles Alleviate Salt Stress in Cotton (Gossypium hirsutum L.) by Adjusting Na+/K+ Ratio and Antioxidative Ability

Soil salinization poses a threat to the sustainability of agricultural production and has become a global issue. Cotton is an important cash crop and plays an important role in economic development. Salt stress has been harming the yield and quality of many crops, including cotton, for many years. In recent years, soil salinization has been increasing. It is crucial to study the mechanism of cotton salt tolerance and explore diversified materials and methods to alleviate the salt stress of cotton for the development of the cotton industry. Nanoparticles (NPs) are an effective means to alleviate salt stress. In this study, zinc oxide NPs (ZnO NPs) were sprayed on cotton leaves with the aim of investigating the intrinsic mechanism of NPs to alleviate salt stress in cotton. The results show that the foliar spraying of ZnO NPs significantly alleviated the negative effects of salt stress on hydroponic cotton seedlings, including the improvement of above-ground and root dry and fresh weight, leaf area, seedling height, and stem diameter. In addition, ZnO NPs can significantly improve the salt-induced oxidative stress by reducing the levels of MDA, H2O2, and O2- and increasing the activities of major antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). Furthermore, RNA-seq showed that the foliar spraying of ZnO NPs could induce the expressions of CNGC, NHX2, AHA3, HAK17, and other genes, and reduce the expression of SKOR, combined with the CBL-CIPK pathway, which alleviated the toxic effect of excessive Na+ and reduced the loss of excessive K+ so that the Na+/K+ ratio was stabilized. In summary, our results indicate that the foliar application of ZnO NPs can alleviate high salt stress in cotton by adjusting the Na+/K+ ratio and regulating antioxidative ability. This provides a new strategy for alleviating the salt stress of cotton and other crops, which is conducive to the development of agriculture.

Mammary epithelium permeability during established lactation: associations with cytokine levels in human milk

Objective

The cytokine profile of human milk may be a key indicator of mammary gland health and has been linked to infant nutrition, growth, and immune system development. The current study examines the extent to which mammary epithelium permeability (MEP) is associated with cytokine profiles during established lactation within a sample of US mothers.

Methods

Participants were drawn from a previous study of human milk cytokines. The present analysis includes 162 participants (98 Black, 64 White) with infants ranging from 1 to 18 months of age. Levels of cytokines were determined previously. Here we measure milk sodium (Na) and potassium (K) levels with ion-selective probes. Two approaches were used to define elevated MEP: Na levels ≥10 mmol/L and Na/K ratios greater than 0.6. Associations between maternal-infant characteristics, elevated MEP, and twelve analytes (IL-6, IL-8, TNFα, IL-1β, FASL, VEGFD, FLT1, bFGF, PLGF, EGF, leptin, adiponectin) were examined using bivariate associations, principal components analysis, and multivariable logistic regression models.

Results

Elevated MEP was observed in 12 and 15% of milk samples as defined by Na and Na/K cutoffs, respectively. The odds of experiencing elevated MEP (defined by Na ≥ 10 mmol/L) were higher among Black participants and declined with older infant age. All cytokines, except leptin, were positively correlated with either Na or the Na/K ratio. A pro-inflammatory factor (IL-6, IL-8, TNFα, IL-1β, EGF) and a tissue remodeling factor (FASL, VEGFD, FLT1, bFGF, PLGF, adiponectin) each contributed uniquely to raising the odds of elevated MEP as defined by either Na or the Na/K ratio.

Conclusion

This exploratory analysis of MEP and cytokine levels during established lactation indicates that elevated MEP may be more common in US populations than previously appreciated and that individuals identifying as Black may have increased odds of experiencing elevated MEP based on current definitions. Research aimed at understanding the role of MEP in mammary gland health or infant growth and development should be prioritized.

Association between sodium and potassium intake levels and body compositions of Chinese college students

BACKGROUND AND OBJECTIVES

To investigate the relationship between sodium (Na) and potassium (K) nutritional condition and body compositions in youth aiming to give target population reasonable diet recommendations.

METHODS AND STUDY DESIGN

The cross-sectional study was conducted involving 512 healthy youth aged 18 to 31 years from universities in Beijing. Food frequency questionnaire (FFQ) and bioelectrical impedance analyzer (BIA) were used to collect dietary intake information and body compositions.

RESULTS

There was an increasing tendency in fat-related indicators and muscle-related indicators of the dietary Na tertile group (p <0.05). Additionally, Weight, body mass index (BMI), waist circumference (WC), and muscle-related indicators increased with the dietary K tertile group (p <0.05). Across increasing tertiles of dietary Na intake, the odds ratio (OR) was increased significantly (p < 0.05) in fat-related indicators. On the contrary, with the increased dietary Na intake, the OR decreased (p < 0.05) in appendicular skeletal muscle mass index (ASMI) and body lean mass. As tertiles of dietary K intake increased, the OR in both skeletal muscle mass index (SMMI) and lean mass index (LMI) decreased.

CONCLUSIONS

High dietary Na is a risk factor for abnormal lipid distribution in college students. High dietary K can maintain skeletal muscle mass and reduce the risk of obesity. Na in the diet has a greater impact on the body composition of young people than K. Low dietary Na and high dietary K still need to be strengthened in science popularization and practice among more college students.

Development of a Method for Estimating Dietary Salt Intake Using the Overnight Urinary Sodium/Potassium Ratio

Background

There are many patients who need to restrict and assess salt in their diet. However, it is difficult to estimate daily salt intake accurately and easily. Therefore, a method for estimating dietary salt intake using the overnight urinary sodium (Na)/potassium (K) ratio was developed.

Methods

The study involved 43 healthy adults (13 males, 30 females). From 2018 to 2020, subjects consumed a salt-adjusted diet for 11 - 30 days continuously, and overnight urine was collected daily. Using the previous day's salt intake as the objective variable, an equation for estimating the salt intake was developed using a general linear model. To verify the accuracy of the estimating equation, the estimated salt intake of the previous day was calculated using our equation and Tanaka's equation, which is an estimating equation from spot urine widely used in clinical practice and epidemiological studies to estimate dietary salt intake, and they were compared with the actual salt intake.

Results

The results of the analysis showed that model 1 (previous day's salt intake (g) = 3.62 + 0.64 × urinary Na/K ratio + 0.18 × conductivity (mS/cm) - 0.43 × sex (male 0, female 1)) was the optimal model. Then, salt intake was estimated using model 1 and Tanaka's equation, and compared with actual salt intake. The Pearson's product-moment correlation coefficient between the actual and estimated salt intake was r = 0.618 (P < 0.001) and r = 0.573 (P < 0.001) for model 1 estimates and Tanaka's equation estimates, respectively. The percentages of errors within ±30% from the actual salt intake were 64.2% and 58.4% for model 1 and Tanaka's equation, respectively.

Conclusion

An equation for estimating salt intake was developed using the Na/K ratio and conductivity of overnight urine. Although the applicability of this method to hypertensive patients and the elderly has not been studied and needs to be clarified in the future, the estimating equation developed is simple and may be a useful method for daily monitoring of dietary salt intake.

Handgrip Strength and Its Association With Hydration Status and Urinary Sodium-to-Potassium Ratio in Older Adults

Objective: Older adults present higher risk of functional disability detected by handgrip strength and an increased risk of poor health conditions, such as dehydration and low values of the sodium-to-potassium (Na/K) ratio. This study aimed to quantify the association of hydration status and Na/K ratio with handgrip strength, based on the urinary excretion of older adults.Methods: A cross-sectional study was conducted in 735 older adults ≥ 65 years old. Handgrip strength was measured with a Jamar Dynamometer and low values were defined according to body mass index and to sex-specific cutoff points. The hydration status was evaluated based on free water reserve. Sodium and potassium intake were evaluated after converting 24-hour urinary sodium and potassium excretion, respectively. A logistic regression model was used to estimate the probability of presenting low handgrip strength, according to risk of hypohydration and to quartiles of Na/K, stratified by sex and adjusted for potential confounders.Results: The adjusted odds ratio (OR) for presenting low handgrip strength was higher in women at risk of hypohydration, but this association was not found in men. Both women and men with the highest values of Na/K ratio presented higher adjusted OR for low handgrip strength (OR in women was 2.03; 95% confidence interval [CI]: 1.12-3.68, and in men was 2.19; 95% CI: 1.11-4.29).Conclusions: The risk of hypohydration was directly associated with low handgrip strength in older women. In older adults, higher values of urinary Na/K ratio were also directly associated with low handgrip strength.

Correlation between Na/K ratio and electron densities in blood samples of breast cancer patients

The main purpose of this study was to investigate the relationship between the electron densities and Na/K ratio which has important role in breast cancer disease. Determinations of sodium and potassium concentrations in blood samples performed with inductive coupled plasma-atomic emission spectrometry. Electron density values of blood samples were determined via ZXCOM. Statistical analyses were performed for electron densities and Na/K ratio including Kolmogorov-Smirnov normality tests, Spearman's rank correlation test and Mann-Whitney U test. It was found that the electron densities significantly differ between control and breast cancer groups. In addition, statistically significant positive correlation was found between the electron density and Na/K ratios in breast cancer group.

The relationship of health/food literacy and salt awareness to daily sodium and potassium intake among a workplace population in Switzerland

BACKGROUND AND AIMS

High sodium (Na) and low potassium (K) intake are associated with hypertension and CVD risk. This study explored the associations of health literacy (HL), food literacy (FL), and salt awareness with salt intake, K intake, and Na/K ratio in a workplace intervention trial in Switzerland.

METHODS AND RESULTS

The study acquired baseline data from 141 individuals, mean age 44.6 years. Na and K intake were estimated from a single 24-h urine collection. We applied validated instruments to assess HL and FL, and salt awareness. Multiple linear regression was used to investigate the association of explanatory variables with salt intake, K intake, and Na/K. Mean daily salt intake was 8.9 g, K 3.1 g, and Na/K 1.18. Salt intake was associated with sex (p < 0.001), and K intake with sex (p < 0.001), age (p = 0.02), and waist-to-height ratio (p = 0.03), as was Na/K. HL index and FL score were not significantly associated with salt or K intake but the awareness variable "salt content impacts food/menu choice" was associated with salt intake (p = 0.005).

CONCLUSION

To achieve the established targets for population Na and K intake, health-related knowledge, abilities, and skills related to Na/salt and K intake need to be promoted through combined educational and structural interventions. Clinical Trials Registry number: DRKS00006790 (23/09/2014).

Estimating 24-h urinary sodium/potassium ratio from casual ('spot') urinary sodium/potassium ratio: the INTERSALT Study

Background

Association between casual and 24-h urinary sodium-to-potassium (Na/K) ratio is well recognized, although it has not been validated in diverse demographic groups. Our aim was to assess utility across and within populations of casual urine to estimate 24-h urinary Na/K ratio using data from the INTERSALT Study.

Methods

The INTERSALT Study collected cross-sectional standardized data on casual urinary sodium and potassium and also on timed 24-h urinary sodium and potassium for 10 065 individuals from 52 population samples in 32 countries (1985-87). Pearson correlation coefficients and agreement were computed for Na/K ratio of casual urine against 24-h urinary Na/K ratio both at population and individual levels.

Results

Pearson correlation coefficients relating means of 24-h urine and casual urine Na/K ratio were r = 0.96 and r = 0.69 in analyses across populations and individuals, respectively. Correlations of casual urine Na/creatinine and K/creatinine ratios with 24-h urinary Na and K excretion, respectively, were lower than correlation of casual and 24-h urinary Na/K ratio in analyses across populations and individuals. The bias estimate with the Bland-Altman method, defined as the difference between Na/K ratio of 24-h urine and casual urine, was approximately 0.4 across both populations and individuals. Spread around, the mean bias was higher for individuals than populations.

Conclusion

With appropriate bias correction, casual urine Na/K ratio may be a useful, low-burden alternative method to 24-h urine for estimation of population urinary Na/K ratio. It may also be applicable for assessment of the urinary Na/K ratio of individuals, with use of repeated measurements to reduce measurement error and increase precision.

Do mothers with high sodium levels in their breast milk have high depression and anxiety scores?

Objective This study aimed to assess the possible association of high breast milk sodium levels with postpartum depression and anxiety. Methods A total of 150 mothers and their healthy, exclusively breastfed newborns aged 8 to 15 days were recruited. Mothers were asked to complete scales for evaluation of postnatal depression and anxiety following an interview for consent and sociodemographic data collection. Breast milk samples were obtained to measure sodium and potassium (K) levels. Results Forty-nine mothers had higher than expected breast milk Na concentrations and a high Na/K ratio. These mothers scored significantly higher on the scales of postnatal depression and state anxiety ( P = 0.018 and P = 0.048, respectively). Conclusions This study shows that compared to normal breast milk Na levels and Na/K ratio, high breast milk Na and high Na/K ratio, with possible serious consequences in infants, are associated with maternal depressive and anxious symptoms in the postpartum period.

Salt Toxicity (Sodium Intake): A Serious Threat to Infants and Children of Pakistan

BACKGROUND

Excess sodium intake can lead to hypertension, the primary risk factor for cardiovascular disease. The aim of this study was to investigate the sodium and potassium contents of foodstuff used by infants and children of Pakistan.

METHODS

We analyzed the sodium and potassium contents of infant milk formula (<6 months), follow up milk formula (>6 months), baby food (cereals), biscuits, fruit juices, potato chips (crisps), cheese puffs, roasted cereals (salty), ice cream cones (kulfi) all of which are the processed food extensively used by the children. The amount of sodium and potassium contents in drinking water of few cities of Pakistan were also considered to assess the additional sodium/potassium in the preparation of milk using infant milk formula.

RESULTS

Na to K ratio (Na:K) was determined 0.3-1.23, 0.3-1.16, 0.33-0.82, 0.54-2.68, 0.51-0.85, 2.86 and 1.02 for infant milk formula (<6 months), follow up milk formula (>6 months), baby food (cereals), biscuits, fruit juices, potato chips (crisps, cheese puffs, roasted cereals), ice cream cones (kulfi), respectively.

CONCLUSION

The higher sodium content is present than most of the quoted values; whereas lower potassium is present than the recommended values. The higher Na:K ratio indicates the severity of the situation where it is commonly stated that "higher an individual's salt intake, the higher an individual's blood pressure". Present study indicates that nearly all Pakistani children consume substantially more salt than they need which will affect health status in later life.

Rice RCN1/OsABCG5 mutation alters accumulation of essential and nonessential minerals and causes a high Na/K ratio, resulting in a salt-sensitive phenotype

Mineral balance and salt stress are major factors affecting plant growth and yield. Here, we characterized the effects of rice (Oryza sativa L.) reduced culm number1 (rcn1), encoding a G subfamily ABC transporter (OsABCG5) involved in accumulation of essential and nonessential minerals, the Na/K ratio, and salt tolerance. Reduced potassium and elevated sodium in field-grown plants were evident in rcn1 compared to original line 'Shiokari' and four independent rcn mutants, rcn2, rcn4, rcn5 and rcn6. A high Na/K ratio was evident in the shoots and roots of rcn1 under K starvation and salt stress in hydroponically cultured plants. Downregulation of SKC1/OsHKT1;5 in rcn1 shoots under salt stress demonstrated that normal function of RCN1/OsABCG5 is essential for upregulation of SKC1/OsHKT1;5 under salt stress. The accumulation of various minerals in shoots and roots was also altered in the rcn1 mutant compared to 'Shiokari' under control conditions, potassium starvation, and salt and d-sorbitol treatments. The rcn1 mutation resulted in a salt-sensitive phenotype. We concluded that RCN1/OsABCG5 is a salt tolerance factor that acts via Na/K homeostasis, at least partly by regulation of SKC1/OsHKT1;5 in shoots.

Responses of three arid zone grass species to varying Na/Ca ratios in saline sand culture

The effects on three grass species, Cenchrus pennisetiformis Hochst. & Steud., Leptnchloa fusca (L.) Kunth. and Panicum turgidum Forssk., of decreasing Ca²⁺ concentration in a saline growth medium were assessed after 7 weeks growth in sand culture. The different Na/Ca ratios of the salt treatment were 24, 49, 99, and 199, at a constant concentration of 200 mol m^-3 . Leptuchloa fusca produced the highest fresh and dry biomass, and was able to maintain Na⁺ and Cl^- Concentrations in the shoots and roots almost constant at varying external Na/Ca ratios, except that the shoot Na⁺ concentration increased significantly at the highest Na/Ca ratio. In C, pennisetiformis the shoot Na⁺ decreased, whereas the shoot Cl^- concentration increased at the highest external Na/Ca ratio. But the root Na⁺ and Cl^- concentrations in this species remained unchanged at varying Na/Ca ratios. C. pennisetiformis and L. fusca maintained almost constant K⁺ and Ca²⁺ concentrations in both shoots and roots at varying Na/Ca ratios. In P. turgidum the shoot K⁺ and shoot and root Ca²⁺ remained almost unchanged at all Na/Ca ratios, whereas the root K⁺ concentration decreased significantly but uniformly at the three, higher Na/Ca ratios. No consistent pattern of increase or decrease was observed in the shoot and root Na/K and Na/Ca ratios of all the species. The shoot selectivity (S_{k + na} ) increased consistently in C pennisetiformis with the increase in Na/Ca ratios and it decreased in L. fusca only at the highest Na/Ca ratio in the growth medium It was established that L. fusca was tolerant, C. penni-setiformis intermediate and P. turgidum relatively sensitive to low Ca²⁺ concentrations of the saline growth medium.