Search

Introduction: Arginine metabolism is involved in the regulation of several biological processes. Many liquid chromatography tandem-mass spectrometry methods for the determination of arginine and its metabolites have been developed but they are time consuming and imply long pre-analytical procedures. The purpose of this study was to develop a rapid method for the simultaneous determination of arginine, citrulline, ornithine, symmetric and asymmetric dimethylarginine and monomethylarginine in human plasma. Materials and methods: The pre-analytical procedure consisted in a simple deproteinization. The chromatographic separation was performed using hydrophilic interaction liquid chromatography. Analytes detection was performed with a triple quadrupole equipped with electrospray ion source operating in positive ion mode. Mass spectrometry experiments were conducted in multiple reaction monitoring mode. Results and conclusions: Recovery ranged from 92.2 to 108.0%. The within-run imprecision and between-run imprecision ranged from 1.5 to 6.8 % and 3.8 to 11.9%, respectively. Carry over and matrix effect did not affect quantitative analysis. Extraction recovery was between 95 and 105 %. Stability after pre-analytical procedure was tested and all the metabolites were stable after 48 h at 4 °C. In conclusion, our novel method allow a rapid and easy determination of arginine and its metabolites both for research and clinical routine use.

Aims/hypothesis: Type 2 diabetes increases the risk of cardiovascular and renal complications, but early risk prediction could lead to timely intervention and better outcomes. Genetic information can be used to enable early detection of risk. Methods: We developed a multi-polygenic risk score (multiPRS) that combines ten weighted PRSs (10 wPRS) composed of 598 SNPs associated with main risk factors and outcomes of type 2 diabetes, derived from summary statistics data of genome-wide association studies. The 10 wPRS, first principal component of ethnicity, sex, age at onset and diabetes duration were included into one logistic regression model to predict micro- and macrovascular outcomes in 4098 participants in the ADVANCE study and 17,604 individuals with type 2 diabetes in the UK Biobank study. Results: The model showed a similar predictive performance for cardiovascular and renal complications in different cohorts. It identified the top 30% of ADVANCE participants with a mean of 3.1-fold increased risk of major micro- and macrovascular events (p = 6.3 × 10−21 and p = 9.6 × 10−31, respectively) and a 4.4-fold (p = 6.8 × 10−33) higher risk of cardiovascular death. While in ADVANCE overall, combined intensive blood pressure and glucose control decreased cardiovascular death by 24%, the model identified a high-risk group in whom it decreased the mortality rate by 47%, and a low-risk group in whom it had no discernible effect. High-risk individuals had the greatest absolute risk reduction with a number needed to treat of 12 to prevent one cardiovascular death over 5 years. Conclusions/interpretation: This novel multiPRS model stratified individuals with type 2 diabetes according to risk of complications and helped to target earlier those who would receive greater benefit from intensive therapy. Graphical abstract: [Figure not available: see fulltext.]

Long COVID, a condition characterized by symptom and/or sign persistence following an acute COVID-19 episode, is associated with reduced physical performance and endothelial dysfunction. Supplementation of l-arginine may improve endothelial and muscle function by stimulating nitric oxide synthesis. A single-blind randomized, placebo-controlled trial was conducted in adults aged between 20 and 60 years with persistent fatigue attending a post-acute COVID-19 outpatient clinic. Participants were randomized 1:1 to receive twice-daily orally either a combination of 1.66 g l-arginine plus 500 mg liposomal vitamin C or a placebo for 28 days. The primary outcome was the distance walked on the 6 min walk test. Secondary outcomes were handgrip strength, flow-mediated dilation, and fatigue persistence. Fifty participants were randomized to receive either l-arginine plus vitamin C or a placebo. Forty-six participants (median (interquartile range) age 51 (14), 30 [65%] women), 23 per group, received the intervention to which they were allocated and completed the study. At 28 days, l-arginine plus vitamin C increased the 6 min walk distance (+30 (40.5) m; placebo: +0 (75) m, p = 0.001) and induced a greater improvement in handgrip strength (+3.4 (7.5) kg) compared with the placebo (+1 (6.6) kg, p = 0.03). The flow-mediated dilation was greater in the active group than in the placebo (14.3% (7.3) vs. 9.4% (5.8), p = 0.03). At 28 days, fatigue was reported by two participants in the active group (8.7%) and 21 in the placebo group (80.1%; p < 0.0001). l-arginine plus vitamin C supplementation improved walking performance, muscle strength, endothelial function, and fatigue in adults with long COVID. This supplement may, therefore, be considered to restore physical performance and relieve persistent symptoms in this patient population.

Type 2 diabetes increases the risk of cardiovascular and renal complications, but early risk prediction can lead to timely intervention and better outcomes. Through summary statistics of meta-analyses of published genome-wide association studies performed in over 1.2 million of individuals, we combined 9 PRS gathering genomic variants associated to cardiovascular and renal diseases and their key risk factors into one logistic regression model, to predict micro- and macrovascular endpoints of diabetes. Its clinical utility in predicting complications of diabetes was tested in 4098 participants with diabetes of the ADVANCE trial followed during a period of 10 years and replicated it in three independent non-trial cohorts. The prediction model adjusted for ethnicity, sex, age at onset and diabetes duration, identified the top 30% of ADVANCE participants at 3.1-fold increased risk of major micro- and macrovascular events (p=6.3x10-21 and p=9.6x10-31, respectively) and at 4.4-fold (p=6.8x10-33) increased risk of cardiovascular death compared to the remainder of T2D subjects. While in ADVANCE overall, combined intensive therapy of blood pressure and glycaemia decreased cardiovascular mortality by 24%, the prediction model identified a high-risk group in whom this therapy decreased mortality by 47%, and a low risk group in whom the therapy had no discernable effect. Patients with high PRS had the greatest absolute risk reduction with a number needed to treat of 12 to prevent one cardiovascular death over 5 years. This novel polygenic prediction model identified people with diabetes at low and high risk of complications and improved targeting those at greater benefit from intensive therapy while avoiding unnecessary intensification in low-risk subjects.