Relationship between estimated glomerular filtration rate, albuminuria, and oxidant status in the Japanese population

Protective Effect of Autologous Arteriovenous Fistulae Against Oxidative Stress in Hemodialyzed Patients

Introduction: Oxidative stress (OS) is ubiquitous in chronic kidney disease (CKD) and is exacerbated by hemodialysis (HD). OS is also associated with anemia, malnutrition, and cardiovascular (CV) disease and is an independent predictor of mortality and morbidity in patients undergoing HD. HD vascular access (VA) types are strongly correlated with CKD patient outcomes. Prolonged use of central venous catheters (CVC) for HD and arteriovenous grafts (AVG) promotes inflammation and OS. However, the effects of the VA type on OS have been poorly studied in HD patients. This study investigated OS prevalence in an HD population to determine the relationship between the VA type and HD.

Methods: The oxidative stress index (OSI) was used to assess the HD patients’ OS status. OSI summarizes information derived from the reactive oxygen metabolites (d-ROMs) fast test and the plasma antioxidant test (PAT) in a single value, using the hydrogen peroxide concentration (for d-ROMs) and ascorbic acid (for PAT) as reference standards. The OSI was created to indicate how far the OS status deviates from normal (i.e., fully compensated oxidative balance). An index increase may be from an increase or decrease in peroxide or antioxidant concentrations. Patients undergoing chronic HD were evaluated by dividing the cases according to the OSI status: normal (N-OSI), borderline (BL-OSI), high (H-OSI), and very high (VH-OSI). Patients with clinical evidence of active infections were excluded.

Results: In total, 129 patients were included; 86.8% used high-flux dialyzers, 13.2% used hemodiafiltration (HDF), and 24.5% were diabetic. An altered OSI was observed in 86 of 129 patients (66.7%). An increased OSI correlated with a significant increase in d-ROMs (r = 0.420) and PAT (r = 0.710). There were no differences between sex, diabetes status, age, dialysis vintage, or dialysis modalities. d-ROMs were inversely correlated with hemoglobin levels (r = −0.209). The iron dose by month correlated with the OSI (r = 0.189) and was significantly lower in the N-OSI group. N- and BL-OSI patients had a significantly higher rate of autologous arteriovenous fistula (AVF) compared to the other groups, and VH-OSI patients had a higher rate of permanent tunneled CVC.

Conclusion: Most HD patients had more OS, indicated by the OSI scores. In chronic HD patients, AVF had a protective effect against imbalanced peroxidation-antioxidation.

Uremic Toxins, Oxidative Stress, Atherosclerosis in Chronic Kidney Disease, and Kidney Transplantation

Patients with chronic kidney disease (CKD) are at a high risk for cardiovascular disease (CVD), and approximately half of all deaths among patients with CKD are a direct result of CVD. The premature cardiovascular disease extends from mild to moderate CKD stages, and the severity of CVD and the risk of death increase with a decline in kidney function. Successful kidney transplantation significantly decreases the risk of death relative to long-term dialysis treatment; nevertheless, the prevalence of CVD remains high and is responsible for approximately 20-35% of mortality in renal transplant recipients. The prevalence of traditional and nontraditional risk factors for CVD is higher in patients with CKD and transplant recipients compared with the general population; however, it can only partly explain the highly increased cardiovascular burden in CKD patients. Nontraditional risk factors, unique to CKD patients, include proteinuria, disturbed calcium, and phosphate metabolism, anemia, fluid overload, and accumulation of uremic toxins. This accumulation of uremic toxins is associated with systemic alterations including inflammation and oxidative stress which are considered crucial in CKD progression and CKD-related CVD. Kidney transplantation can mitigate the impact of some of these nontraditional factors, but they typically persist to some degree following transplantation. Taking into consideration the scarcity of data on uremic waste products, oxidative stress, and their relation to atherosclerosis in renal transplantation, in the review, we discussed the impact of uremic toxins on vascular dysfunction in CKD patients and kidney transplant recipients. Special attention was paid to the role of native and transplanted kidney function.

Microalbuminuria as a potential biomarker for Parkinson's disease severity: A hypothesis

Parkinson's disease (PD) is the second most common neurodegenerative condition characterized by motor and non-motor symptoms causing a great burden in patients' quality of life. PD has been associated with various metabolic factors such as diabetes, hypertension, and more recently chronic kidney disease where proteinuria has been associated with an increased risk. The presence of small amounts of albumin in urine, microalbuminuria, is a common biomarker for endothelial damage and a predictive factor for not only cardiovascular but also neurological dysfunction. Multiple studies have assessed potential biomarkers for PD progression with great heterogeneity, we hypothesize the use of microalbuminuria as a potential marker that correlates with PD severity and might represent a feasible and simple method of evaluating PD patients in clinical practice. Evidence supporting the present hypothesis comes from oxidative stress, insulin resistance, and endothelial dysfunction. Oxidative stress is a key element in PD pathogenesis; studies have shown lower antioxidant capacity as PD progresses. On the other side, insulin signaling plays an important role in neuronal growth and survival, with its resistance being associated with PD. Microalbuminuria has been associated with both processes; increased levels of oxidative stress markers and decreased insulin sensitivity, hence its screening in PD might reflect these common pathological mechanisms. Moreover, the low vitamin D levels observed in PD patients, which are correlated with endothelial dysfunction and disease severity, might contribute to microalbuminuria induction. More evidence on this vascular approach comes from white matter lesions (WML), observed in brain imaging, which have been significantly associated with motor and non-motor function in PD patients and are independently associated with microalbuminuria. In this manner, an oxidant and insulin resistant environment, along with low vitamin D levels in PD patients, which are associated with microalbuminuria, might contribute altogether to WML. As the latter are correlated with motor and non-motor function, microalbuminuria might thus give insight on PD status. Prospective cohort studies with an adequate sample size, follow-up, and a thorough battery of clinical tests for PD are needed to confirm this hypothesis.

Protective factors as biomarkers and targets for prevention and treatment of diabetic nephropathy: From current human evidence to future possibilities

Although hyperglycemia, high blood pressure and aging increase the risk of developing kidney complications, some diabetes patients exposed to these risk factors do not develop kidney disease, suggesting the presence of endogenous protective factors. There is a growing need to understand these factors determining protection of the kidney in order to improve the design of preventive strategies and to enhance the processes responsible for renoprotection. The aim of this review was to present the existing molecular and epidemiological data on factors showing protective effects in diabetic kidney disease, and to summarize the evidence regarding their potential in the area of future clinical diagnostics, therapeutics and early preventive strategies. These include transcriptomic and proteomic studies regarding the anti-inflammatory, anti-fibrotic and regenerative factors that were associated with slower progression of renal function loss. Another focus is the new evidence regarding the evaluation of alterations in the regulatory epigenome and its involvement in the risk of diabetic kidney disease. Further effort is required to validate and extend these findings, and to define their potential for clinical implementation in the future.

Biochemical Implications of Biotransformation of Some Toxic Floras Using Natural Local Enzyme Sources

BACKGROUND

Recently, it has been established that simultaneous saccharification and fermentation is a potent technique for the detoxification of harmful plant materials.

OBJECTIVE

Following encouraging simultaneous medicinal applications of snail slime and yeast, we exploited their hydrolytic and fermentation potentials to prevent toxicities of the selected floras; Erythrodontium barteri (EB), bracken fern (BF), and crustose lichens (CL). The applicability of the saccharification process has been described in a patent (WO2005010193A2).

METHODS

The plants were bioprocessed using snail digestive juice and yeast slurry and their health effects were evaluated. Seventy rats were divided equally into groups, treated with single doses of aqueous extracts of the plants and their bioprocessed forms, and compared with control rats.

RESULTS

The plants showed very high antinutrients levels, which significantly reduced after SSF with enhanced flavonoids, alkaloids and phenols. Potential alterations of WBC differentials, RBC, liver and renal function markers indices were mitigated by bioprocessed extracts. MDA, SOD, GRase, XO and XDH levels in rats administered the bEB and CL were equivalent to the levels found for the control rats. Some bioprocessed plants produced unaltered insulin, ghrelin, and leptin levels. The bioprocessed extracts, when compared to the effects of unprocessed extracts, produced lower TNF-α, Caspase-3, and adiponectin levels and mitigated the potential suppression of Na+/K+-ATPase levels. Potential depletion of inhibin-B, testosterone, estrogen, and prolactin was mitigated after bioprocessing.

CONCLUSION

This study, thus, validates the application of bioprocessing using snail digestive juice and yeast as an effective approach to reduce the potential toxicities of harmful plants.

The association between oxidative stress and corneal hysteresis in patients with glaucoma

Systemic antioxidative status has been implicated in glaucoma pathogenesis. Additionally, corneal hysteresis (CH) may contribute to glaucoma progression. Here, we evaluated the relationship between biological antioxidant potential (BAP) and CH. This study included 103 patients with open-angle glaucoma (OAG). We used a free radical analyzer to measure BAP, and an ocular response analyzer to measure CH and corneal resistance factor (CRF). We evaluated the relationship between systemic oxidative stress and other clinical parameters with Spearman's rank correlation test and a multi-regression analysis. BAP was not correlated to either CH or CRF in the male or female OAG patients. BAP was correlated to both CH and CRF in the female OAG patients older than 57 years (r = 0.51, P = 0.003; r = 0.49, P = 0.004), but uncorrelated in the female OAG patients younger than 57 years. Multiple regression analysis revealed that BAP independently contributed to CH (P = 0.025) and CRF (P = 0.015) in the older female OAG patients. Systemic oxidative stress may significantly affect the viscoelasticity of the cornea in older female OAG patients. Future studies are needed to confirm that low systemic antioxidative status and low corneal hysteresis contribute to glaucoma pathogenesis.

Possible anti-oxidative effects of long-term administration of Juzen-taiho-to in dogs

It is known that oxidative stress is related to disease in humans and dogs. Many traditional Chinese medicines have been reported to have anti-oxidative effects, but there are no reports that they have anti-oxidative effects in dogs. In this study, we examined the anti-oxidative effects of Juzen-taiho-to, a traditional Chinese medicine, in dogs. Five healthy female beagle dogs (38–41 months of age weighing 8.6–10.7 kg) were orally administered Juzen-taiho-to at 450 mg/kg with food for 28 days. Blood samples were taken from all five dogs on days 0, 7, 14, 21, and 28. Using the blood samples, improvement of the antioxidant level as assessed by the biological antioxidant potential (BAP), reduced oxidative stress level as assessed by derivatives of reactive oxygen metabolites (d-ROMs), and improvement of blood fluidity were examined. Regarding the antioxidant level and blood fluidity, no significant difference was observed, but the oxidative stress level on days 14, 21, and 28 was significantly lower than that on day 0. Thus, Juzen-taiho-to may have anti-oxidative effects in dogs by reducing oxidative stress and be useful for oxidative stress-related diseases in dogs.

Association of glucose and blood pressure variability on oxidative stress in patients with type 2 diabetes mellitus and hypertension: a cross-sectional study

BACKGROUND

The present study evaluated the effects of glucose and blood pressure (BP) variability on oxidative stress in patients with type 2 diabetes mellitus (T2DM) and hypertension.

METHODS

A total of 60 inpatients with T2DM underwent continuous glucose monitoring (CGM) and ambulatory BP monitoring (ABPM). Oxidative stress was estimated using the diacron-reactive oxygen metabolites (d-ROMs) test. Glucose variability, mean glucose level, percentage coefficient of variation for glucose, mean amplitude of glycemic excursions (MAGE), and area under the postprandial plasma glucose curve were determined through CGM. BP variability was assessed by measuring average BP, standard deviation (SD) of systolic and diastolic BP, and coefficient of variation (CV) of systolic and diastolic BP during daytime and nighttime ABPM.

RESULTS

Participants had a mean age of 64.5 ± 13.3 years with the duration of the disease 13.9 ± 12.4 years and HbA1c of 8.5 ± 1.2%. Univariate analysis showed that MAGE, nighttime SDs of systolic and diastolic BP, and nighttime CV of systolic BP were significantly correlated with d-ROMs. Further, stepwise multiple regression analysis identified MAGE, nighttime SD and CV of diastolic BP, estimated glomerular filtration rate, and smoking as independent contributors to d-ROMs.

CONCLUSIONS

Oxidative stress was associated with daily glucose and nighttime diastolic BP variability in patients with T2DM and hypertension.Trial registration UMIN Clinical Trial Registry UMIN000035615, Registered January 22, 2019-retrospectively registered.

Age- and sex-dependency of the association between systemic antioxidant potential and glaucomatous damage

Systemic oxidative stress is thought to be an important factor in the pathogenesis of glaucoma. In particular, low systemic antioxidative capacity, which normally counters oxidative stress, may contribute to glaucoma. Thus, we investigated the association between biological antioxidant potential (BAP), a biomarker of systemic antioxidative capacity, and glaucoma severity in patients with open-angle glaucoma (OAG). This study included 480 eyes of 240 patients with OAG and 66 healthy control eyes. We measured the BAP serum level with a free radical analyzer and compared it with a weighted estimate of the number of retinal ganglion cells (wrgc), derived from circumpapillary retinal nerve fiber layer thickness and visual field mean deviation. We found that wrgc was uncorrelated with BAP in the overall, male, and female OAG patients, but was correlated in young (aged ≤ 65 years) male OAG patients (better eye: r = 0.33, P = 0.02; worse eye: r = 0.27, P = 0.047). Furthermore, a mixed-effects regression analysis revealed that BAP was an independent contributing factor to wrgc in young male OAG patients (P = 0.02). Thus, systemic antioxidant capacity was associated with glaucomatous damage in relatively young male patients, suggesting that anti-oxidant therapy might be more effective in these patients.

Usefulness of the d-ROMs test for prediction of cardiovascular events

BACKGROUND

d-ROMs test developed to determine the degree of individual oxidative stress may predict cardiovascular events.

METHODS AND RESULTS

265 patients (204 men, 61 women; age, 65±13years) who had been treated for cardiovascular disease were divided evenly by quartile of baseline d-ROMs levels, and were followed up. During the observation periods of 2.66±1.47years, there were 14 (5%) deaths, 8 (3%) cardiovascular deaths, 13 (5%) major adverse cardiovascular events (MACEs), and 51 (19%) all cardiovascular events including heart failure, cardiovascular surgery, and revascularization. Log-rank tests demonstrated that the patients in the 4th quartile (d-ROMs≧395.00U.CARR) had a higher incidence rate of cardiovascular death than those in the 2nd quartile (d-ROMs 286.00-335.00, p=0.022). In multivariate Cox regression analysis, even after adjustment for age, sex, coronary risk factors, C-reactive protein, and renal function, high d-ROMs was a risk factor for all-cause death [adjusted HR of 4th vs. 1st quartile, 10.791 (95% confidence interval 1.032-112.805), p=0.047], and all cardiovascular events [HR of 4th vs. 1st quartile, 2.651 (95% confidence interval 1.138-6.177), p=0.024].

CONCLUSIONS

Our results suggest that d-ROMs is a useful oxidative stress marker to assess prognosis and risk of further cardiovascular events.

Reduction of a marker of oxidative stress with enhancement of iron utilization by erythropoiesis activation following epoetin beta pegol administration in iron-loaded db/db mice

Iron, an essential element for various biological processes, can induce oxidative stress. We hypothesized that iron utilization for erythropoiesis, stimulated by epoetin beta pegol (C.E.R.A.), a long-acting erythropoiesis-stimulating agent, contributes to the reduction of iron-induced oxidative stress. We first investigated the sensitivity of several biomarkers to detect oxidative stress in mice by altering the amount of total body iron; we then investigated whether C.E.R.A. ameliorated oxidative stress through enhanced iron utilization. We treated db/db mice with intravenous iron-dextran and evaluated several biomarkers of iron-induced oxidative stress. In mice loaded with 5 mg/head iron, hepatic iron content was elevated and the oxidative stress marker d-ROMs (serum derivatives of reactive oxygen metabolites) was increased, whereas urinary 8-hydroxy-2'-deoxyguanosine and serum malondialdehyde were not, indicating that d-ROMs is a sensitive marker of iron-induced oxidative stress. To investigate whether C.E.R.A. ameliorated oxidative stress, db/db mice were intravenously administered iron-dextran or dextran only, followed by C.E.R.A. Hemoglobin level increased, while hepatic iron content decreased after C.E.R.A.

TREATMENT

Serum d-ROMs decreased after C.E.R.A. treatment in the iron-dextran-treated group. Our results suggest that C.E.R.A. promotes iron utilization for erythropoiesis through mobilization of hepatic iron storage, leading to a decrease in serum oxidative stress markers in iron-loaded db/db mice.

The Pivotal Role of a Novel Biomarker of Reactive Oxygen Species in Chronic Kidney Disease

Risk stratification of chronic kidney disease (CKD) is clinically important because such patients are at high risk of cardiovascular events. Although reactive oxygen species (ROS) are reported to be closely associated with the pathophysiology of CKD, there are few useful ROS biomarkers known for CKD patients. Hence, our objectives in this study were to investigate whether serum derivatives of reactive oxygen metabolites (DROM), a novel biomarker of ROS, is involved in the pathophysiology of CKD (case-control study), and is a significant predictor of future cardiovascular events in CKD patients (follow-up study).Patients with suspected coronary artery disease (CAD) were enrolled and underwent coronary angiography. Patients with CKD (estimated glomerular filtration ratio <60  mL/min/1.73 m(2)  and/or proteinuria, n = 324) were compared with those without CKD (non-CKD). Serum DROM was measured at stable conditions. A case-control study of the 324 CKD patients and 263 non-CKD patients was conducted after matching risk factors, and a follow-up study of the 324 CKD patients was performed. CKD patients were divided into low- and high-DROM groups using their median value (348 unit; called the Carratelli unit [U.CARR]), and followed until the occurrence of cardiovascular events.DROM levels were significantly higher in risk factors-matched CKD patients than in risk factors-matched non-CKD patients (347.0 [301.8-391.8] U.CARR vs. 338.5 [299.8-384.3] U.CARR, P = 0.03). During mean 23 ± 14 months follow-up of 324 CKD patients, 83 cardiovascular events were recorded. Kaplan-Meier analysis demonstrated a higher probability of cardiovascular events in CKD patients with high DROM than in those with low DROM (P < 0.001, log-rank test). Multivariate Cox hazard analysis including significant predictors in simple Cox hazard analysis demonstrated that high DROM was a significant and independent predictor of cardiovascular events in CKD patients (hazard ratio: 1.76, 95% confidence interval: 1.10-2.82, P = 0.02).In conclusion, serum DROM values were significant and independent predictors of cardiovascular events in CKD patients, indicating that the measurements of DROM might provide clinical benefits for risk stratification of CKD patients.

Relationship between serum uric acid and serum oxidative stress markers in the Japanese general population

BACKGROUND

Increased production of reactive oxygen species is a condition that is associated with, and plays a role in the progression of, various disorders such as hypertension, atherosclerosis, and diabetes.

PURPOSE

To assess in vivo oxidative stress levels and antioxidant potential and to analyze the relationship with serum uric acid (UA) levels.

METHODS AND RESULTS

Oxidative stress levels (derivatives of reactive oxygen metabolites, d-ROMs) and antioxidant potential (biological antioxidant potential, BAP) were measured in individuals who underwent a general health screening test, and data were analyzed from 8,025 individuals (2,953 women and 5,072 men) who were free from UA-lowering medication. Higher serum UA levels were associated with increased levels of d-ROMs in both genders, and this trend was more prominent in women. In addition, higher UA levels were also associated with higher BAP in both genders, although the dose dependence was not apparent in men. These associations remained statistically significant after adjusting for age, blood pressure, renal function, albuminuria, C-reactive protein, and insulin resistance index.

CONCLUSIONS

In individuals who underwent general health screening, serum UA levels were positively associated with both d-ROMs and BAP levels. Whether lowering of UA by lifestyle modification or by medication alters d-ROM/BAP levels awaits further investigations. .