The causal relationship of human blood metabolites with the components of Sarcopenia: a two-sample Mendelian randomization analysis.

BACKGROUND: Sarcopenia is a progressive loss of muscle mass and function. Since skeletal muscle plays a critical role in metabolic homeostasis, identifying the relationship of blood metabolites with sarcopenia components would help understand the etiology of sarcopenia. METHODS: A two-sample Mendelian randomization study was conducted to examine the causal relationship of blood metabolites with the components of sarcopenia. Summary genetic association data for 309 known metabolites were obtained from the Twins UK cohort and KORA F4 study (7824 participants). The summary statistics for sarcopenia components [hand grip strength (HGS), walking pace (WP), and appendicular lean mass (ALM)] were obtained from the IEU Open GWAS project (461,089 participants). The inverse variance weighted method was used, and the MR-Egger, weighted median, and MR-PRESSO were used for the sensitivity analyses. Metabolic pathways analysis was further performed. RESULTS: Fifty-four metabolites associated with sarcopenia components were selected from 275 known metabolites pool. Metabolites that are causally linked to the sarcopenia components were mainly enriched in amino sugar and nucleotide sugar metabolism, galactose metabolism, fructose and mannose metabolism, carnitine synthesis, and biotin metabolism. The associations of pentadecanoate (15:0) with ALM, and 3-dehydrocarnitine and isovalerylcarnitine with HGS were significant after Bonferroni correction with a threshold of P < 1.82 × 10- 4 (0.05/275). Meanwhile, the association of hyodeoxycholate and glycine with the right HGS, and androsterone sulfate with ALM were significant in the sensitivity analyses. CONCLUSION: Blood metabolites from different metabolism pathways were causally related to the components of sarcopenia. These findings might benefit the understanding of the biological mechanisms of sarcopenia and targeted drugs development for muscle health.

The agreement of different techniques for muscle measurement in diagnosing sarcopenia: a systematic review and meta-analysis.

Background: The measurement or estimation of muscle mass plays an important role in the diagnosis of sarcopenia. Beside dual-energy X-ray absorptiometry (DXA), several modalities, including bioelectrical impedance analysis (BIA), ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI), have helped to provide imaging or electrical biomarkers for muscle mass. This study was aimed at summarizing the diagnostic performance of different techniques on muscle assessment for sarcopenia. Methods: Studies on the assessment of muscle mass by different techniques (compared with DXA), published from inception to 12 October, 2023 were retrieved from 4 electronic databases: the Cochrane Library, Embase, PubMed, and Web of Science. The quality assessment of included studies was conducted using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). The sensitivity, specificity, Cohen's kappa coefficient (κ), and Pearson correlation coefficient (r) with 95% confidence intervals (CIs) were pooled and presented via forest plots. The area under the curve (AUC) with 95% CI was pooled and presented via summary receiver operating characteristic (sROC) curve. Results: A total of 28 studies involving 4,926 participants were included. Compared with DXA, the pooled sensitivity and specificity, AUC, and Cohen's κ were 0.79 (95% CI: 0.71-0.86, P<0.001), 0.95 (95% CI: 0.82-0.99, P<0.001), and 0.88 (95% CI: 0.85-0.90), and 0.61 (95% CI: 0.51-0.72) for BIA. The pooled r value between DXA and BIA or US or MRI was 0.94 (95% CI: 0.92-0.96, P<0.001), 0.69 (95% CI: 0.54-0.80, P<0.001), and 0.96 (95% CI: 0.95-0.97, P=0.21), respectively. No qualified original study in relation to CT was included. Conclusions: BIA, US, and MRI would provide acceptable diagnostic accuracy for sarcopenia by evaluating muscle mass in terms of sensitivity, specificity, accuracy, and their higher correlations with DXA. Further investigation is required to elucidate the value of CT in diagnosing sarcopenia.

Effects of Nitrogen Accumulation, Transportation, and Grain Nutritional Quality and Advances in Fungal Endophyte Research in Quinoa (Chenopodium quinoa Willd.) Plants.

This study aims to understand the influence of nitrogen accumulation, fungal endophyte, yield, nitrogen use efficiency, and grain nutritional quality parameters on the yield of quinoa in some areas of China. The endophytic microbial community in plants plays a crucial role in plant growth, development, and health, especially in quinoa plants under different nitrogen fertilizer levels. The results from the present study indicated that appropriate nitrogen application significantly enhanced the nitrogen accumulation and yield of quinoa grains during maturity, increasing by 34.54-42.18% and 14.59-30.71%, respectively. Concurrently, protein content, amylose, total starch, ash, and fat content also increased, with respective growth rates of 1.15-18.18%, 30.74-42.53%, 6.40-12.40%, 1.94-21.94%, and 5.32-22.22%. Our constructed interaction network of bacterial and fungal communities revealed that bacteria outnumbered fungi significantly, and most of them exhibited synergistic interactions. The moderate increase in N150 was beneficial for increasing quinoa yield, achieving nitrogen use efficiency (NUE) of over 20%. The N210 was increased, and both the yield and NUE significantly decreased. This study provides novel insights into the impact of nitrogen fertilizer on quinoa growth and microbial communities, which are crucial for achieving agricultural sustainable development.

Nitrogen Application Can Optimize Form of Selenium in Soil in Selenium-Rich Areas to Affect Selenium Absorption and Accumulation in Black Wheat.

The composition and form of selenium in the soil have significant effects on the selenium content of crops. In this study, we investigated the selenium absorption pathway in plants by studying the interaction between nitrogen fertilizer and soil selenium. Our results showed that the selenium concentration enrichment factors (CEF) varied within the same region due to nitrogen fertilizer application, where they ranged from 1.33 to 5.02. The soil selenium flow coefficient (mobility factor, MF) increased with higher nitrogen application rates. The sum of the MF values for each soil layer treated with nitrogen application rates of 192 kg hm-2 and 240 kg hm-2 was 0.70, which was 64% higher than that for the control group with no nitrogen application. In the 0-20 cm soil layer, the highest summed water-soluble and exchangeable selenium and relative percentage of total selenium (12.45%) was observed at a nitrogen application rate of 240 kg hm-2. In the 20-40 cm soil layer, the highest relative percentage content of water-soluble and exchangeable selenium and total selenium (12.66%) was observed at a nitrogen application rate of 192 kg hm-2. Experimental treatment of black wheat with various concentrations of sodium selenite showed that selenium treatment at 50 µmol L-1 significantly increased the reduced glutathione (GSH) levels in the leaves and roots of seedlings, where the GSH contents increased by 155.4% in the leaves and by 91.5% in the roots. Further analysis of the soil-black wheat system showed that nitrogen application in selenium-rich areas affected the soil selenium flow coefficient and morphological composition, thereby changing the enrichment coefficient for leaves (0.823), transport capacity from leaves to grains (-0.530), and enrichment coefficient for roots (0.38). These changes ultimately affected the selenium concentration in the grains of black wheat.