Pre-Infection Nutritional Status, Oxidative Stress, and One-Year-Long COVID Persistence in Patients Undergoing Hemodialysis: A Prospective Cohort Study.

BACKGROUND: Nutritional status's role in long COVID is evident in the general population, yet unexplored in patients undergoing hemodialysis (HD), posing a research gap. We hypothesized that pre-infection undernutrition in HD patients might impact long COVID persistence by accelerating oxidative stress. The present study aimed to investigate the association between pre-infection nutritional status, oxidative stress, and one-year-long COVID persistence in HD patients. METHODS: This prospective observational cohort study enrolled 115 HD patients with confirmed COVID-19. Nutritional status was assessed using the Controlling Nutritional Status (CONUT) score twice: before infection and three months post-infection. Oxidative markers included malondialdehyde (MDAs), ceruloplasmin, transferrin, and sulfhydryl groups. The endpoint was one-year-long COVID persistence. RESULTS: Moderate pre-infection CONUT scores were associated with heightened severe undernutrition risk (p < 0.0001), elevated MDAs (p < 0.0001), and reduced ceruloplasmin levels (p = 0.0009) at three months post-COVID-19 compared to light CONUT scores. Pre-infection CONUT score independently predicted post-COVID oxidative damage [OR 2.3 (95% CI 1.2; 4.6), p < 0.0001] and one-year-long COVID persistence [HR 4.6 (95% CI 1.4; 9.9), p < 0.0001], even after adjusting for potential confounders. CONCLUSION: Moderate pre-infection undernutrition heightens post-COVID oxidative stress and increases the risk of one-year-long COVID persistence in HD patients.

Gut Microbiota's Oxalate-Degrading Activity and Its Implications on Cardiovascular Health in Patients with Kidney Failure: A Pilot Prospective Study.

Background and Objectives: The present study aims to investigate the association between gut microbiota's oxalate-degrading activity (ODA) and the risk of developing cardiovascular disease (CVD) over a three-year follow-up period in a cohort of patients undergoing kidney replacement therapy (KRT). Additionally, various factors were examined to gain insight into the potential mechanisms underlying the ODA-CVD link. Materials and Methods: A cohort of 32 KRT patients and 18 healthy volunteers was enrolled in this prospective observational pilot study. Total fecal ODA, routine clinical data, plasma oxalic acid (POx), serum indoxyl sulfate, lipid profile, oxidative stress, and proinflammatory markers were measured, and the patients were followed up for three years to assess CVD events. Results: The results revealed that patients with kidney failure exhibited significantly lower total fecal ODA levels compared to the healthy control group (p = 0.017), with a higher proportion showing negative ODA status (≤-1% per 0.01 g) (p = 0.01). Negative total fecal ODA status was associated with a significantly higher risk of CVD events during the three-year follow-up period (HR = 4.1, 95% CI 1.4-16.3, p = 0.003), even after adjusting for potential confounders. Negative total fecal ODA status was significantly associated with elevated POx and indoxyl sulfate levels and linked to dyslipidemia, increased oxidative stress, and inflammation, which are critical contributors to CVD. Conclusions: The findings contribute novel insights into the relationship between gut microbiota's ODA and cardiovascular health in patients undergoing KRT, emphasizing the need for further research to elucidate underlying mechanisms and explore potential therapeutic implications of targeting gut microbiota's ODA in this vulnerable population.

Oxalate Balance in Peritoneal Dialysis Patients: A Potential Role of Dialysis-related Peritonitis.

BACKGROUND: Little evidence is available on oxalate balance in peritoneal dialysis (PD) patients. PATIENTS AND METHODS: We performed a cross-sectional observational pilot study with 62 adult PD patients to document oxalate balance and explore its association with PD-related peritonitis. Plasma oxalate concentration, levels of oxalate excretion in 24-h urine, and peritoneal dialysis effluent were evaluated. The peritoneal oxalate transport status and renal and peritoneal oxalate clearances were calculated according to the PD-related peritonitis history. RESULTS: PD patients with a history of peritonitis had a statistically significantly lower peritoneal oxalate clearance, daily peritoneal oxalate excretion, and overall oxalate removal rate compared with the peritonitis-free PD patients. They had a 4-fold risk of plasma oxalic acid increase, and even a single episode of dialysis-related peritonitis resulted in plasma oxalate elevation. CONCLUSION: Peritoneal oxalate clearance plays an important role in oxalate balance in PD patients and, therefore, dialysis-related peritonitis is a significant predictor for hyperoxalemia. Further well-designed clinical trials need to be undertaken before the association between peritonitis and oxalate balance in PD patients is more clearly understood.

Plasma oxalic acid and cardiovascular risk in end-stage renal disease patients: a prospective, observational cohort pilot study.

BACKGROUND/AIMS: It was hypothesized that oxalate might be strongly involved in atherogenesis and the inflammatory pathway that could result in an increased risk of cardiovascular disease (CVD) in end-stage renal disease (ESRD) patients. Therefore, this study aimed to address two primary research questions: to characterize the lipid profile and the pattern of pro-inflammatory cytokines according to plasma oxalic acid (POx) concentration in ESRD patients; to evaluate the potential role of elevated POx concentration in the development of CVD risk. METHODS: A total of 73 participants were enrolled in this prospective, observational cohort pilot study. Among them, there were 50 ESRD patients and 23 healthy volunteers. The lipid profile and the pro-inflammatory cytokines were analyzed according to the distribution of POx concentration into tertiles. After the clinical examination, 29 hemodialysis patients and 21 peritoneal dialysis patients without prevalent CVD were observed for CVD events for 2 years. The Cox regression analysis and a set of different types of sensitivity analyses were used to determine whether elevated POx was associated with an increased risk of CVD. RESULTS: An increasing trend in the atherogenic lipoprotein fractions and the pro-inflammatory markers as well as a linear decrease in high-density lipoprotein was significantly associated with elevated POx. POx concentration ≥ 62.9 µmol/L was significantly associated with CVD events independently of other examined CVD risk factors. CONCLUSION: This pilot study firstly demonstrated a potential contribution of POx to atherogenesis, inflammation and CVD risk in ESRD patients.

Oxidative Stress in Peritoneal Dialysis Patients: Association with the Dialysis Adequacy and Technique Survival.

INTRODUCTION: Increased oxidative stress is suggested as one of the possible mechanisms of structural and functional damage to the peritoneal membrane in peritoneal dialysis patients. But there are few available data on the association of oxidative stress with peritoneal dialysis adequacy and technique survival. The present study was undertaken to investigate the association of oxidative stress biomarkers with the peritoneal dialysis adequacy and technique survival. METHODS: This prospective single-center observational study was conducted between January 2010 and May 2015. Adequacy of dialysis, malondialdehyde levels in the serum and erythrocytes (as an indicator of lipid peroxidation), the concentration of ceruloplasmin, transferrin, and sulfhydryl groups in the blood, and total peroxidase activity in erythrocyte (as indicators of antioxidant system) were determined in 44 stable ambulatory non-diabetic peritoneal dialysis patients. RESULTS: The follow-up period was 3 years. We identified a negative correlation between the serum level of malondialdehyde in the patients and total weekly Kt/V. Peritoneal weekly CrCl was positively correlated with the levels of transferrin, total peroxidase activity, and SH- groups. Daily peritoneal ultrafiltration had a positive correlation with the total peroxidase activity and the serum transferrin levels. The results of the Kaplan-Meier analysis and the log-rank test also demonstrated a significant difference in the cumulative technique survival rate between the patients with ceruloplasmin level ≤0.19 g/l and ≥0.2 g/l. CONCLUSIONS: The results mentioned above could be considered as one of the ways to explain better technique survival in PD patients.