Xanthine oxidase and uric acid as independent predictors of albuminuria in patients with diabetes mellitus type 2

Emerging Roles of Xanthine Oxidoreductase in Chronic Kidney Disease

Xanthine Oxidoreductase (XOR) is a ubiquitous, essential enzyme responsible for the terminal steps of purine catabolism, ultimately producing uric acid that is eliminated by the kidneys. XOR is also a physiological source of superoxide ion, hydrogen peroxide, and nitric oxide, which can function as second messengers in the activation of various physiological pathways, as well as contribute to the development and the progression of chronic conditions including kidney diseases, which are increasing in prevalence worldwide. XOR activity can promote oxidative distress, endothelial dysfunction, and inflammation through the biological effects of reactive oxygen species; nitric oxide and uric acid are the major products of XOR activity. However, the complex relationship of these reactions in disease settings has long been debated, and the environmental influences and genetics remain largely unknown. In this review, we give an overview of the biochemistry, biology, environmental, and current clinical impact of XOR in the kidney. Finally, we highlight recent genetic studies linking XOR and risk for kidney disease, igniting enthusiasm for future biomarker development and novel therapeutic approaches targeting XOR.

Are Oxidative Stress Biomarkers Reliable Part of Multimarker Panel in Female Patients with Type 2 Diabetes Mellitus?

Background: Oxidative stress and inflammation are the key features of metabolic diseases, including type 2 diabetes mellitus (T2D). However, studies that explored redox homeostasis parameters in relation to T2D show discrepant results. Accordingly, we aimed to examine the potential reliability of oxidative stress biomarkers [i.e., determined by malondialdehyde (MDA), advanced oxidation protein products (AOPP) and catalase (CAT)] in addition to traditional cardiometabolic parameters in relation to T2D in female cohort. Methods: A total of 214 women (of them 40.6% T2D) were consecutively recruited in the study. Principal component analysis with varimax rotation was performed to determine the adequate number of factors consisting of anthropometric, traditional cardiometabolic and redox status markers. Results: MDA and AOPP concentrations were lower, but CAT activity was higher in T2D group as compared with controls (P < 0.001, P = 0.002, P < 0.001). Traditional markers related factor (i.e., with positive loading of waist circumference, triglycerides, uric acid, high sensitivity C-reactive protein and negative loadings of high-density lipoprotein cholesterol) was found to be independently related with T2D in multivariate binary regression analysis, whereas oxidative stress related factor (i.e., with positive loading of MDA and AOPP) lost its independent prediction after adjustment for confounding factors (i.e., age, menopausal status, antihypertensive, and hypolipemic therapies). Increased Traditional markers related factor was associated with more than three times higher probability for T2D onset (OR = 3.319, p < 0.001). Conclusion: Oxidative stress biomarkers, i.e., MDA, AOPP, and CAT are not superior over traditional cardiometabolic markers in relation to T2D in female population. Future studies with both gender included are needed to confirm such results.

Serum uric acid levels and health outcomes in CKD: a prospective cohort study

BACKGROUND

Hyperuricemia is prevalent in individuals with chronic kidney disease (CKD). Elevated serum uric acid (SUA) concentrations have been considered an independent risk factor for the onset of CKD. However, the relationship between SUA concentrations and long-term health outcomes among patients with CKD remains unclear.

METHODS

We performed a prospective cohort study with nationally representative sample to investigate the relationship between SUA concentrations and mortality risk including all-cause, cardiovascular disease (CVD) and cancer mortality, among patients with CKD. The weighted restricted cubic spline analyses combined with the multivariate-adjusted Cox proportional hazard models were used to test the nonlinearity of relationship.

RESULTS

The 6642 patients participating in National Health and Nutrition Examination Survey 1999-2018 were enrolled. During 656 885 person-months of follow-up time, 2619 all-cause deaths were recorded, including 1030 CVD deaths and 458 cancer deaths. Our study presented J-shaped non-linear relationships between SUA concentrations and all-cause and CVD mortality with inflection points at 311.65 μmol/L and 392.34 μmol/L, respectively. When SUA concentration was higher than those inflection points, every increase of 50 μmol/L SUA was associated with 11.7% and 17.0% greater multivariable-adjusted hazard ratio of all-cause and CVD mortality, respectively. In addition, a negative linear correlation with cancer mortality was detected.

CONCLUSION

These findings suggested that maintaining appropriate SUA concentrations may improve long-term health outcomes among CKD patients. The corresponding inflection points of J-shaped non-linear relationships were 311.65 and 392.34 μmol/L for all-cause and CVD mortality. Further clinical trials are required to investigate uric acid-lowering targets.

Temporal change of serum xanthine oxidase levels and its relation to clinical outcome of severe traumatic brain injury: a prospective cohort study

Xanthine oxidase (XO) may be involved in the induction of oxidative stress and inflammation. We measured serum XO levels at multiple days to determine whether it is associated with the severity and prognosis of severe traumatic brain injury (sTBI). In this prospective cohort study, we quantified serum XO levels in 112 sTBI patients and 112 controls. Serum XO levels of patients were measured at admission and at days 1, 3, 5, 7, and 10 after sTBI. Extended Glasgow outcome scale scores of 1-4 at post-trauma 180 days were defined as a poor prognosis. Multivariate analysis was employed to determine the relationship between poor prognosis and serum XO levels at multiple days. Serum XO levels were significantly increased at admission among patients, afterwards elevated gradually, peaked at day 3, and then diminished gradually until day 10, and were substantially higher during 10 days in patients than in controls. Serum XO levels at 6 different days were all correlated with admission Rotterdam computed tomography (CT) scores and Glasgow coma scale (GCS) scores. Serum XO levels at 6 different days were all substantially higher in patients with poor prognosis than in those with good prognosis. Serum XO levels at days 7 and 10, but not at days 1, 3, and 5, had significantly lower area under receiver operating characteristic (AUC) than those at admission. Serum XO levels at admission and at days 1 and 3, but not at day 5, were independently associated with 180-day poor prognosis. Prognostic prediction model containing GCS scores, Rotterdam CT scores, and serum XO levels at admission (or at days 1 and 3) showed substantially higher AUC than GCS scores and Rotterdam CT scores alone. The models were visually described using nomograms, which were comparatively stable under calibration curve and were relatively of clinical benefit under decision curve. Elevated serum XO levels during early period of sTBI are more closely associated with trauma severity and clinical adverse outcomes, assuming that serum XO may serve as a potential prognostic biomarker in sTBI.

Ethnic disparities in bidirectional causal effects between serum uric acid concentrations and kidney function: Trans-ethnic Mendelian randomization study

Introduction

Researchers have investigated the causal effect between serum uric acid (SUA) concentrations and kidney function for decades, but studies produced inconsistent results. This study aimed to clarify the bidirectional causal effects between SUA concentrations and kidney function and to explore the potential ethnic disparities by conducting a trans-ethnic Mendelian randomization study in European, African, and Asian ancestries.

Materials and methods

The summary-level data for this study were obtained from the Global Urate Genetics Consortium, CKDGen Consortium, UK Biobank, and Japan Biobank for different outcomes and exposures, respectively. The traits of kidney function were estimated glomerular filtration rate from serum creatinine (eGFRcr), estimated glomerular filtration rate from cystatin C (eGFRcys), and blood urea nitrogen (BUN). Using the multiplicative random-effects inverse variance weighting mode, our primary analysis produced robust results despite heterogeneity. Additionally, we performed the Mendelian randomization pleiotropy residual sum and outlier test to eliminate the horizontal pleiotropy and obtain accurate results.

Results

Our findings revealed that elevated SUA concentrations had causal effects on declined eGFRcys, BUN, and a diagnosis of chronic kidney disease in European ancestries and eGFRcr in Asian ancestries. Additionally, the causal effects of declined eGFRcr and elevated BUN concentrations on elevated SUA concentrations were observed in both European and Asian ancestries. However, no bidirectional causal effect was found between SUA concentrations and eGFRcr among African ancestries.

Conclusions

This trans-ethnic Mendelian randomization study confirmed the bidirectional causal effects between SUA concentrations and kidney function and highlighted the importance of considering ethnic disparities in clinical treatments.

Association of circulatory PCSK-9 with biomarkers of redox imbalance and inflammatory cascades in the prognosis of diabetes and associated complications: a pilot study in the Indian population

AbstractsBesides the profound role of proprotein convertase subtilisin/kexin type-9 (PCSK-9) in LDL-C regulation, its association with other metabolic complications cannot be disregarded. The co-existence of redox imbalance and inflammatory cascades has greatly reflected the etiology of hyperglycemia. Therefore, we studied the association of PCSK-9 with inflammation and oxidative stress biomarkers to predict its role in the prognosis of diabetes and its associated complications in the Indian population. This pilot study examined a total of n = 187 subjects: healthy controls (HC; n = 50), diabetic without complication (T2DM; n = 49), diabetic nephropathy (T2DM-N; n = 43), and diabetic dyslipidemic (T2DM-DL; n = 45) subjects. The relationship between circulatory PCSK-9 levels and inflammation and redox imbalance biomarkers has been explored. The significant positive association of elevated PCSK-9 level with the inflammatory (i.e. IL-1β, IL-6, TNF-α, and CRP) and oxidative stress marker (i.e. XOD, CD, LOOH, and MDA) was observed in T2DM-N and T2DM-DL subjects. Whereas single regression analysis depicted that PCSK-9 was inversely associated with the FRAP and PON-1 in T2DM-N and T2DM-DL subjects. Furthermore, no significant correlation was detected in both T2DM and HC subjects. We found a significant relationship between these prognostic biomarkers with an elevated level of PCSK-9 in T2DM-N and T2DM-DL subjects. PCSK-9 is a nontraditional biomarker in diabetes that may help identify patients at risk of developing secondary complications of diabetes in the Indian population. However, further large cohort validation studies are needed.

The Serum Uric Acid to Serum Creatinine Ratio is an Independent Risk Factor for Diabetic Kidney Disease

PURPOSE

A retrospective study was designed to evaluate whether the serum uric acid to serum creatinine ratio (SUA/SCr) can be used as an indicator of diabetic kidney disease (DKD) and macroangiopathy in patients with type 2 diabetes mellitus (T2DM).

PATIENTS AND METHODS

We screened 2227 patients diagnosed with T2DM, and 450 patients were finally included. They were assigned to three groups based on the tertile of SUA/SCr (Group Tertile 1, Tertile 2, Tertile 3). Demographic information and biochemical parameters were collected from Electronic Patient Record (EPR).

RESULTS

The estimated glomerular filtration rate (eGFR) values were lowest in Group Tertile 1 and highest in Group Tertile 3 (P < 0.05). There was no significant difference in urinary albumin creatinine ratio (UACR) among the three groups (P > 0.05). Partial correlation analyses revealed that SUA/SCr levels were significantly and positively correlated with eGFR, SUA, body mass index, gamma-glutamyl transpeptidase, alanine transaminase, triglycerides, C-peptide, high-density lipoprotein cholesterol and fatty liver, while they were negatively correlated with SCr, blood urea nitrogen, cystatin-c, age, male sex, DM duration and hypertension history (P < 0.05). Logistic regression analysis revealed that SUA/SCr was an independent risk factor for eGFR < 60 mL/min/1.73 m² (P < 0.05). The ROC curve showed that the cutoff value of SUA/SCr for the identification of eGFR < 60 mL/min/1.73 m² was 3.434. In patients with normal UACR, SUA/SCr levels of patients with eGFR < 60 mL/min/1.73 m² were lower than those with eGFR ≥ 60 mL/min/1.73 m² (P < 0.05). Regression analysis did not show SUA/SCr associate to macrovascular disease after adjusting for confounding factors.

CONCLUSION

SUA/SCr is an independent risk factor for DKD in patients with T2DM and may be helpful for identifying normoalbuminuric DKD.

Xanthine oxidoreductase: A leading actor in cardiovascular disease drama

Cardiovascular diseases (CVD) are the leading cause of global mortality and their pathogenesis lies mainly in the atherosclerotic process. There are close connections linking oxidative stress and inflammation to endothelial dysfunction, atherosclerosis and, consequently, to CVD. This review focuses on the role of xanthine oxidoreductase (XOR) and its products on the development of chronic inflammation and oxidative stress, responsible for atheromatous plaque formation. Evidence is reported that an excessive level of XOR products favors inflammatory response and plaque development, thereby promoting major cardiovascular risk factors. Also, the relationship between hyperuricemia and hypertension as well as between XOR activity and CVD is confirmed. In spite of the increasing number of clinical studies investigating the output of cardiovascular patients treated with urate-lowering therapies (including uricosuric drugs, XOR inhibitors and recombinant uricase) the results are still uncertain. The inhibition of XOR activity appears more promising than just the control of uricemia level in preventing cardiovascular events, possibly because it also reduces the intracellular accumulation of urate, as well as the production of reactive oxygen species. However, XOR inhibition also reduces the availability of the multifaced mediator nitric oxide and, at present, can be recommended only in hyperuricemic patients.

Serum Uric Acid and Coronary Arterial Disease in Predialysis Chronic Kidney Disease Patients

Background–Aim:

Uric acid is considered a marker of high cardiovascular risk. We investigated the association between serum uric acid and coronary arterial disease (CAD) in pre-dialysis chronic kidney disease (CKD) patients.

Methods:

We enrolled 110 subjects on mean age 69.02 ± 14.3 years old. The participants were categorized for both estimated glomerular filtration rate (eGFR) and albuminuria according to criteria 2012 of the Kidney Disease Improving Global Outcomes. Estimated pulse wave velocity (ePWV) was calculated using an equation including the age and mean blood pressure. The CAD prevalence rate was recorded.

Results:

The patients were divided in two groups according to uric acid cutoff point value related to high ePWV. The patients with higher uric acid were older and they had significantly higher systolic blood pressure, pulse pressure, and parathyroid hormone, but significantly lower eGFR and 1,25(OH)2 Vit D3 levels. The association between high uric acid and both high ePWV and CAD occurrence was found to be significant ( x2 = 6.7, P = .008 and x2 = 4.1, P = .03, respectively), although the relationship with albuminuria was found to be nonsignificant. In a built multifactorial model, the low serum uric acid rather than the high was found to be an independent predictor for CAD demonstration entering traditional and specific confounders.

Conclusion:

The low serum uric acid levels were proved to be a significant predictor for CAD accounting potential covariates, even though the high uric acid per se was found to be connected with cardiovascular disease characteristics including arterial stiffness in predialysis CKD patients.

Early onset of hyperuricemia is associated with increased cardiovascular disease and mortality risk

BACKGROUND

Hyperuricemia is associated with cardiovascular mortality, but the association of the age at hyperuricemia onset with cardiovascular disease (CVD) and mortality is still unclear.

OBJECTIVE

The purpose of this study was to examine the associations of hyperuricemia onset age with CVD and all-cause mortality.

METHODS

A total of 82,219 participants free of hyperuricemia and CVD from 2006 to 2015 in the Kailuan study were included. The analysis cohort comprised 18,311 new-onset hyperuricemia patients and controls matched for age and sex from the general population. Adjusted associations were estimated using Cox models for CVD and all-cause mortality across a range of ages.

RESULTS

There were 1,021 incident cases of CVD (including 215 myocardial infarctions, 814 strokes) and 1459 deaths during an average of 5.2 years of follow-up. Patients with hyperuricemia onset at an age < 45 years had the highest hazard ratios (HRs) (1.78 (1.14-2.78) for CVD and 1.64 (1.04-2.61) for all-cause mortality relative to controls). The HRs of CVD and all-cause mortality were 1.32 (1.05-1.65) and 1.40 (1.08-1.81) for the 45-54 years age group, 1.23 (0.97-1.56) and 1.37 (1.11 to 1.72) for the 55-64 years age group, and 1.10 (0.88-1.39) and 0.88 (0.76-1.01) for the ≥ 65 years age group, respectively.

CONCLUSIONS

The age at hyperuricemia onset was identified as an important predictor of CVD and all-cause mortality risk, and the prediction was more powerful in those with a younger age of hyperuricemia onset. Early onset of hyperuricemia is associated with increased cardiovascular disease and mortality risk.

Risk Predictors of High Uric Acid Levels Among Patients with Type-2 Diabetes

OBJECTIVE

Patients with diabetes are at higher risk of the negative consequences of hyperuricemia. The objective of this study was to investigate gender and age-specific differences in the uric acid levels and to evaluate the associated risk factors among patients with diabetes.

METHODS

A retrospective cross-sectional study was conducted at Strategic Center for Diabetes Research from September 2019 to January 2020, among adult type-2 diabetic patients. Serum uric acid (SUA) and several other metabolic and clinical parameters were examined. Multiple regression analysis was done to identify risk factors independently associated with hyperuricemia.

RESULTS

A total of 433 patients were included in the analysis. SUA level was higher in males than females (5.82±1.65 mg/dL versus 5.29±1.54 mg/dL, p < 0.001). The prevalence of hyperuricemia was higher in females than males (28.8% versus 20.5%, p = 0.049). There was no significant difference in uric acid levels or the prevalence of hyperuricemia by age groups in the total sample or gender-stratified samples. In multivariate analysis, hyperuricemia was associated with bigger hip circumference (odds ratios [OR] were 1.03, 95% CI = 1.01-1.05), higher triglycerides (OR = 1.005, 95% CI = 1.002-1.008), and higher serum creatinine (OR = 1.34, 95% CI = 1.21-1.49). Hip circumference, total cholesterol, high-density lipoprotein, and serum creatinine were independent risk factors in males, while triglycerides and higher serum creatinine were independent risk factors among females.

CONCLUSION

The present study demonstrates gender-specific differences in the uric acid levels and hyperuricemia prevalence. In males and females, hyperuricemia was associated with hip circumference, total cholesterol, high-density lipoprotein, triglycerides, and serum creatinine. Future large studies are needed to confirm our findings, especially in elderly females.

Uric Acid and Cardiovascular Disease: An Update From Molecular Mechanism to Clinical Perspective

Uric acid (UA) is the end product of purine nucleotide metabolism in the human body. Hyperuricemia is an abnormally high level of UA in the blood and may result in arthritis and gout. The prevalence of hyperuricemia has been increasing globally. Epidemiological studies have shown that UA levels are positively correlated with cardiovascular diseases, including hypertension, atherosclerosis, atrial fibrillation (AF), and heart failure (HF). Hyperuricemia promotes the occurrence and development of cardiovascular diseases by regulating molecular signals, such as inflammatory response, oxidative stress, insulin resistance/diabetes, endoplasmic reticulum stress, and endothelial dysfunction. Despite extensive research, the underlying molecular mechanisms are still unclear. Allopurinol, a xanthine oxidase (XO) inhibitor, has been shown to improve cardiovascular outcomes in patients with HF, coronary heart disease (CHD), type 2 diabetes (T2D), and left ventricular hypertrophy (LVH). Whether febuxostat, another XO inhibitor, can improve cardiovascular outcomes as well as allopurinol remains controversial. Furthermore, it is also not clear whether UA-lowering treatment (ULT) can benefit patients with asymptomatic hyperuricemia. In this review, we focus on the latest cellular and molecular findings of cardiovascular disease associated with hyperuricemia and clinical data about the efficacy of ULT in patients with cardiovascular disease.

Endocan and a novel score for dyslipidemia, oxidative stress and inflammation (DOI score) are independently correlated with glycated hemoglobin (HbA1c) in patients with prediabetes and type 2 diabetes

INTRODUCTION

We aimed to examine serum endocan level and the summary involvement of dyslipidemia, oxidative stress (OS) and inflammation by calculation of its comprehensive score (i.e. Dyslipidemia-Oxy-Inflammation (DOI) score) in relation to glucoregulation in subjects with prediabetes and overt type 2 diabetes (T2D).

MATERIAL AND METHODS

A total of 59 patients with prediabetes and 102 patients with T2D were compared with 117 diabetes-free controls. Glycated hemoglobin (HbA_1c), inflammation, OS and lipid parameters were measured. Associations of clinical data with HbA_1c level were tested with univariate and multivariate logistic ordinal regression analysis. HbA_1c as a dependent variable is given at the ordinal level (i.e. < 5.7%; 5.7-6.4%, > 6.4%, respectively).

RESULTS

Endocan was significantly higher in the T2D group than in the controls. As endocan concentration rose by 1 unit, the probability for higher HbA_1c concentration increased by more than 3 times (OR = 3.69, 95% CI: 1.84-7.01, p < 0.001). Also, a rise in the dyslipidemia score, oxy score, inflammation score and DOI score by 1 unit increased the probability of higher HbA_1c concentration by 19%, 13%, 51% and 11%, respectively. In the models, after adjustment for confounding variables, endocan and DOI score remained independent predictors of HbA_1c level.

CONCLUSIONS

Endocan and DOI score are independently correlated with HbA_1c in patients with prediabetes and overt T2D.

Relationship between serum uric acid and clustering of cardiovascular disease risk factors and renal disorders among Shanghai population: a multicentre and cross-sectional study

OBJECTIVES

To estimate the current prevalence of cardiovascular disease risk factors (CRFs) and renal disorders across serum uric acid (SUA) quartiles, and evaluate the relationships between SUA and CRFs and renal diseases in Shanghai population.

STUDY DESIGN

Observational, cross-sectional study.

SETTING

Data were obtained from the physical check-up of local residents at three hospitals in Shanghai.

PARTICIPANTS

Residents were invited to take part in a physical check-up and provided informed consent. Exclusion criteria were diseases that resemble cancer, hepatic disease, and other coexisting illnesses including autoimmune kidney diseases and renal artery stenosis, individuals treated with xanthine oxidase inhibitors, and those with incomplete information. There are 26 768 individuals in our study.

PRIMARY AND SECONDARY OUTCOME MEASURES

Hyperuricaemia was defined as SUA ≥7 mg/dL in men and ≥6 mg/dL in women or taking xanthine oxidase inhibitors. Subjects were divided into gender-specific quartiles. We estimate the prevalence of CRFs and renal disorders across SUA quartiles. The relationships between SUA and CRFs and renal disorders in both genders were evaluated using logistic regression analysis.

RESULTS

There was a significant increase in the prevalence of major CRFs and renal diseases across SUA quartiles in a separate analysis among men and women (all p trend <0.001). After multiple adjustment, hyperuricaemia positively correlated with obesity (male OR=3.165, p<0.001; female OR=3.776, p<0.001), hypertension (male OR=1.341, p<0.001; female OR=1.289, p=0.006), dyslipidaemia (male OR=2.490, p<0.001; female OR=3.614, p<0.001), chronic kidney disease (male OR=7.081, p<0.001; female OR=11.571, p<0.001) and nephrolithiasis (male OR=1.469, p<0.001; female OR=1.242, p=0.041), but negatively correlated with diabetes mellitus (male OR=0.206, p<0.001; female OR=0.524, p<0.001). There was a stronger association between hyperuricaemia and clustered CRFs as well as chronic kidney disease in women than in men.

CONCLUSIONS

In Shanghai population, concomitant with the elevated level of SUA, the prevalence of CRFs and renal diseases was rising. Hyperuricaemia was significantly associated with CRFs and renal disorders, especially in women.

Effects of Uric Acid on Diabetes Mellitus and Its Chronic Complications

With the deepening of the researches on uric acid, especially in the study of metabolic diseases, uric acid has been found to be closely related to obesity, metabolic syndrome, nonalcoholic fatty liver disease, diabetes, and other metabolic diseases. Uric acid causes a series of pathophysiological changes through inflammation, oxidative stress, vascular endothelial injury, and so on and thus subsequently promotes the occurrence and development of diseases. This review confirmed the positive correlation between uric acid and diabetes mellitus and its chronic complications through the pathogenesis and clinical studies aspects.

Effect of Diabetes Mellitus on the Pharmacokinetics and Pharmacodynamics of Tuberculosis Treatment

Diabetes mellitus (DM) and tuberculosis (TB) are two common diseases with increasing geographic overlap and clinical interactions. The effect of DM and hemoglobin A1c (HbA1c) values on the pharmacokinetics (PK) and pharmacodynamics (PD) of anti-TB drugs remains poorly characterized. Newly diagnosed TB patients with and without DM starting fixed-dose, thrice-weekly treatment underwent sampling for PK assessments (predose and 0.5, 2, and 6 h postdose) during the intensive and continuation phases of treatment. The effect of DM and HbA1c values on the maximum concentration (C _max) of rifampin, isoniazid, and pyrazinamide and the association between drug concentrations and microbiologic and clinical outcomes were assessed. Of 243 patients, 101 had DM. Univariate analysis showed significant reductions in the C _max of pyrazinamide and isoniazid (but not rifampin) with DM or increasing HbA1c values. After adjusting for age, sex, and weight, DM was associated only with reduced pyrazinamide concentrations (adjusted geometric mean ratio = 0.74, P = 0.03). In adjusted Cox models, female gender (adjusted hazards ratio [aHR] = 1.75, P = 0.001), a lower smear grade with the Xpert assay (aHR = 1.40, P < 0.001), and the pyrazinamide C _max (aHR = 0.99, P = 0.006) were independent predictors of sputum culture conversion to negative. Higher isoniazid or rifampin concentrations were associated with a faster time to culture conversion in patients with DM only. A pyrazinamide C _max above the therapeutic target was associated with higher unfavorable outcomes (treatment failure, relapse, death) (odds ratio = 1.92, P = 0.04). DM and higher HbA1c values increased the risk of not achieving therapeutic targets for pyrazinamide (but not rifampin or isoniazid). Higher pyrazinamide concentrations, though, were associated with worse microbiologic and clinical outcomes. DM status also appeared to influence PK-PD relationships for isoniazid and rifampin.

Methylene blue alleviates endothelial dysfunction and reduces oxidative stress in aortas from diabetic rats

Endothelial dysfunction and the related increase in reactive oxygen species (ROS) production are important events in the pathophysiology of diabetes mellitus (DM). Methylene blue (MB) has been systematically investigated for its protective effects against refractory hypotension and mitochondrial dysfunction. We have previously demonstrated that MB improved mitochondrial respiration and partially decreased oxidative stress in diabetic rat hearts. The present study was aimed to investigate whether MB modulates vascular function and ROS production in thoracic aortic rings isolated from rats with streptozotocin-induced DM (after 4 weeks of hyperglycemia). The effects of MB (0.1 μM, 30 min ex vivo incubation) on vascular reactivity in organ chamber (phenylephrine-induced contraction, acetylcholine-induced relaxation) and H₂O₂ production (assessed by ferrous iron xylenol orange oxidation assay) were investigated in vascular preparations with intact endothelium and after denudation. DM elicited a significant alteration of vascular function: increased contractility to phenylephrine, attenuation of acetylcholine-dependent relaxation, and augmented H₂O₂ generation. Ex vivo incubation with MB partially reversed all these changes (by approximately 70%) in vascular segments with intact endothelial layer (but not in denuded vessels). In conclusion, MB might be useful in alleviating endothelial dysfunction and mitigating endothelial oxidative stress, observations that clearly require further investigation in the setting of cardiometabolic disease.

Retinol-binding protein 4 versus albuminuria as predictors of estimated glomerular filtration rate decline in patients with type 2 diabetes

Background

Since the increase in some tubular damage biomarkers can be observed at the early stage of diabetic nephropathy, even in the absence of albuminuria, we aimed to investigate if urinary albumin is superior than tubular damage marker, such as serum retinol-binding protein 4 (RBP4), in predicting renal function decline (defined as estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m²) in the cohort of patients with type 2 diabetes mellitus (T2D).

Materials and Methods

A total of 106 sedentary T2D patients (mean [± standard deviation] age 64.9 [±6.6] years) were included in this cross-sectional study. Anthropometric and biochemical parameters (fasting glucose, glycated hemoglobin [HbA1c], lipid parameters, creatinine, RBP4, high sensitivity C-reactive protein [hsCRP], urinary albumin excretion [UAE]), as well as blood pressure were obtained.

Results

HsCRP (odds ratio [OR] =0.754, 95% confidence interval [CI] (0.603-0.942), P = 0.013) and RBP4 (OR = 0.873, 95% CI [0.824-0.926], P < 0.001) were independent predictors of eGFR decline. Moreover, although RBP4 and UAE as single diagnostic parameters of renal impairment showed excellent clinical accuracy (area under the curve [AUC] = 0.900 and AUC = 0.940, respectively), the Model which included body mass index, HbA1c, triglycerides, hsCRP, and RBP4 showed statistically same accuracy as UAE, when UAE was used as a single parameter (AUC = 0.932 vs. AUC = 0.940, respectively; P for AUC difference = 0.759). As well, the Model had higher sensitivity and specificity (92% and 90%, respectively) than single predictors, RBP4, and UAE.

Conclusion

Although serum RBP4 showed excellent clinical accuracy, just like UAE, a combination of markers of tubular damage, inflammation, and traditional markers has the higher sensitivity and specificity than UAE alone for prediction renal impairment in patients with T2D.