Ischemic heart diseases in Egypt: role of xanthine oxidase system and ischemia-modified albumin

A comprehensive review of synthetic and semisynthetic xanthine oxidase inhibitors: identification of potential leads based on in-silico computed ADME characteristics

Xanthine oxidase (XO) inhibitors, both synthetic and semisynthetic, have been developed extensively over the past few decades. The increased level of XO is not only the major cause of gout but is also responsible for various conditions associated with hyperuricemia, such as cardiovascular disorders, chronic kidney disorders, diabetes, Alzheimer's disease and chronic wounds. Marketed available XO inhibitors (allopurinol, febuxostat, and topiroxostat) are used to treat hyperuricemia but they are associated with fatal side effects, which pose serious problems for the healthcare system, rising the need for new, more potent, safer compounds. This review summarizes recent findings on XO and describes their design, synthesis, biological significance in the development of anti-hyperuricemic drugs with ADME profile, structure activity relationship (SAR) and molecular docking studies. The results might help medicinal chemists to develop more efficacious XO inhibitors.

Evaluation of Plasma Xanthine Oxidoreductase (XOR) Activity in Patients with Cardiopulmonary Arrest

Plasma xanthine oxidoreductase (XOR) activity in patients with cardiopulmonary arrest (CPA) has not yet been studied.A total of 1,158 patients who required intensive care and 231 control patients who attended a cardiovascular outpatient clinic were prospectively analyzed. Blood samples were collected within 15 minutes of admission from patients in intensive care patients, which were divided into a CPA group (n = 1,053) and a no-CPA group (n = 105). Plasma XOR activity was compared between the 3 groups and factors independently associated with extremely elevated XOR activity were identified using a multivariate logistic regression model. Plasma XOR activity in the CPA group (median, 1,030.0 pmol/hour/mL; range, 233.0-4,240.0 pmol/hour/mL) was significantly higher than in the no-CPA group (median, 60.2 pmol/hour/mL; range, 22.5-205.0 pmol/hour/mL) and control group (median, 45.2 pmol/hour/mL; range, 19.3-98.8 pmol/hour/mL). The regression model showed that out-of-hospital cardiac arrest (OHCA) (yes, odds ratio [OR]: 2.548; 95% confidence interval [CI]: 1.098-5.914; P = 0.029) and lactate levels (per 1.0 mmol/L increase, OR: 1.127; 95% CI: 1.031-1.232; P = 0.009) were independently associated with high plasma XOR activity (≥ 1,000 pmol/hour/mL). Kaplan-Meier curve analysis indicated that the prognosis, including all-cause death within 30 days, was significantly poorer in high-XOR patients (XOR ≥ 6,670 pmol/hour/mL) than in the other patients.Plasma XOR activity was extremely high in patients with CPA, especially in OHCA. This would be associated with a high lactate value and expected to eventually lead to adverse outcome in patients with CPA.

Protective Effects of Caesalpinia sappan Linn. and Its Bioactive Compounds on Cardiovascular Organs

Cardiovascular diseases are the leading cause of death worldwide. The long-term aim of cardiovascular disease therapy is to reduce the mortality rate and decelerate the progression of cardiovascular organ damage. Current therapies focus on recovering heart function and reducing risk factors such as hyperglycemia and dyslipidemia. However, oxidative stress and inflammation are important causes of further damage to cardiovascular organs. Caesalpinia sappan Linn. (Fabaceae), a flowering tree native to tropical Asia, has antioxidant and anti-inflammatory properties. It is used as a natural dye to color food and beverages and as a traditional treatment for diarrhea, diabetes, and blood stasis. The phytochemical compounds in C. sappan, mainly the homoisoflavonoids brazilin, sappanone A, protosappanin, and hematoxylin, can potentially be used to protect cardiovascular organs. This review aims to provide updates on recent developments in research on C. sappan in relation to treatment of cardiovascular diseases. Many studies have reported protective effects of the plant’s bioactive compounds that reduce cardiac damage and enhance vasorelaxation. For example, brazilin and sappanone A have an impact on molecular and cellular changes in cardiovascular disease pathogenesis, mainly by modulating oxidative, inflammatory, and apoptotic signaling pathways. Therefore, bioactive compounds of C. sappan have the potential to be developed as therapeutic agents to combat cardiovascular diseases like myocardial infarction and vascular disease. This review could help further the understanding of the possible modulatory role of the compounds in cardiovascular diseases, thereby facilitating future studies.

Time-dependent changes in plasma xanthine oxidoreductase during hospitalization of acute heart failure

Aims

The aim of present study is to evaluate the clinical significance of the time‐dependent changes in xanthine oxidoreductase (XOR) activity during hospitalization for acute heart failure (AHF).

Methods and results

A total of 229 AHF patients who visited to emergency room were prospectively enrolled, and 187 patients were analysed. Blood samples were collected within 15 min of admission (Day 1), after 48–72 h (Day 3), and between Days 7 and 21 (Day 14). The AHF patients were divided into two groups according to the XOR activity on Day 1: the high‐XOR group (≥100 pmol/h/mL, n = 85) and the low‐XOR group (<100 pmol/h/mL, n = 102). The high‐XOR patients were assigned to two groups according to the rate of change in XOR from Day 1 to Day 14: the decreased group (≥50% decrease; n = 70) and the non‐decreased group (<50% decrease; n = 15). The plasma XOR activity significantly decreased on Days 3 and 14 [23.6 (9.1 to 63.1) pmol/h/mL and 32.5 (10.2 to 87.8) pmol/h/mL, respectively] in comparison with Day 1 [78.5 (16.9 to 340.5) pmol/h/mL]. A Kaplan–Meier curve indicated that the prognosis, including heart failure (HF) events (all‐cause death and readmission by HF) within 365 days, was significantly poorer in the low‐XOR patients than in the high‐XOR patients and was also significantly poorer in the non‐decreased group than in the decreased group.

Conclusions

The plasma XOR activity was rapidly decreased by the appropriate treatment of AHF. Although high‐XOR activity on admission was not associated with increased HF events in AHF, high‐XOR activity that was not sufficiently reduced during appropriate treatment was associated with increased HF events.

Characteristics of Patients with an Abnormally Decreased Plasma Xanthine Oxidoreductase Activity in Acute Heart Failure Who Visited the Emergency Department

Background: The factors associated with a low plasma xanthine oxidoreductase (XOR) activity were not elucidated in patients with acute heart failure (AHF). Methods: Two-hundred and twenty-nine AHF patients who visited the emergency department were prospectively analyzed. AHF patients were divided into 3 groups according to the plasma XOR quartiles (Q1 = low-XOR group [n = 57], Q2/Q3 = middle-XOR group [n = 115], and Q4 = high-XOR group [n = 57]). The prognostic nutritional index (PNI) and the controlling nutritional status (CONUT) score were evaluated. Results: The multivariate logistic regression model showed that the nutritional status (PNI: OR 1.044, 95% CI 1.000–1.088; CONUT: OR 3.805, 95% CI 1.158–12.498), age, and serum creatinine level were independently associated with a low plasma XOR activity. The Kaplan-Meier curve showed a significantly lower incidence of heart failure events in the low-XOR group than in the middle + high-XOR group (hazard ratio, HR 1.648, 95% CI 1.061–2.559). In particular, a low XOR activity with an increased serum creatinine level (>1.21 mg/dL) was independently associated with heart failure events (HR 1.937, 95% CI 1.199–3.130). Conclusion: A low plasma XOR activity was associated with malnutrition, renal dysfunction, and aging in AHF. A low XOR activity complicated with renal dysfunction leads to adverse long-term outcomes.

Plasma xanthine oxidoreductase (XOR) activity in patients who require cardiovascular intensive care

Hyperuricemia is known to be associated with adverse outcomes in cardiovascular intensive care patients, but its mechanisms are unknown. A total of 569 emergency department patients were prospectively analyzed and assigned to intensive care (ICU group, n = 431) or other departments (n = 138). Uric acid (UA) levels were significantly higher in the intensive care patients (6.3 [5.1-7.6] mg/dl vs. 5.8 [4.6-6.8] mg/dL). The plasma xanthine oxidoreductase (XOR) activity in the ICU group (68.3 [21.2-359.5] pmol/h/mL) was also significantly higher than that in other departments (37.2 [15.1-93.6] pmol/h/mL). Intensive care patients were divided into three groups according to plasma XOR quartiles (Q1, low-XOR, Q2/Q3, normal-XOR, and Q4, high-XOR group). A multivariate logistic regression model showed that lactate (per 1.0 mmol/L increase, OR 1.326; 95%, CI 1.166-1.508, p < 0.001) and the Acute Physiology and Chronic Health Evaluation II score (per 1.0 point increase, OR 1.095, 95% CI 1.034-1.160, p = 0.002) were independently associated with the high-XOR group. In-hospital mortality was significantly higher in the high-XOR group (n = 28, 26.2%) than in the normal- (n = 11, 5.1%) and low- (n = 9, 8.3%) XOR groups. The high-XOR group (vs. normal-XOR group) was independently associated with the in-hospital mortality (OR 2.934; 95% CI 1.170-7.358; p = 0.022). Serum UA levels and plasma XOR activity were high in patients admitted to intensive care. The enhanced XOR activity may be one of the mechanisms under which hyperuricemia was associated with adverse outcomes in patients requiring cardiovascular intensive care.

Plasma Xanthine Oxidoreductase (XOR) Activity in Cardiovascular Disease Outpatients

Background: The mechanisms of the increased plasma xanthine oxidoreductase (XOR) activity in outpatients with cardiovascular disease were unclear.

Methods and Results: A total of 372 outpatients were screened, and 301 outpatients with cardiovascular disease were prospectively analyzed. Blood samples were collected from patients who visited a daily cardiovascular outpatient clinic. Patients with diabetes mellitus (DM) were significantly more likely to be classified into the high-XOR group (≥100 pg/h/mL; 50%) than the low-XOR group (<100 pmol/h/mL; 28.7%). On multivariate logistic regression analysis, DM (OR, 2.683; 95% CI: 1.441–4.996) was independently associated with high plasma XOR activity in all cohorts. In the diabetic cardiovascular disease patients (n=100), median body mass index (BMI) in the high-XOR group (28.0 kg/m²; IQR, 25.2–29.4 kg/m², n=32) was significantly higher than in the low-XOR group (23.6 kg/m²; IQR, 21.2–25.7 kg/m², n=68), and BMI was independently associated with high plasma XOR activity (OR, 1.340; 95% CI: 1.149–1.540). Plasma hydrogen peroxide was significantly higher in DM patients with high plasma XOR activity and obesity (>22 kg/m²) than in other patients.

Conclusions: DM with obesity is one of the mechanisms of XOR enhancement in cardiovascular disease. The increase of XOR is a possible pathway for the production of reactive oxygen species in obese cardiovascular disease patients with DM.

Serum neopterin and ischemia modified albumin levels are associated with the disease activity of adult immunoglobulin A vasculitis (Henoch-Schönlein purpura)

AIM

The aims of the study are to investigate serum neopterin and ischemia modified albumin (IMA) levels in patients with immunoglobulin A vasculitis (IgAV) and evaluate the association of these markers with disease activity and relapse.

METHOD

Thirty-four consecutive adult patients (24 male and 10 female) admitted to the rheumatology clinic and met the IgAV American College of Rheumatology (ACR) criteria were enrolled in this cross-sectional study. Demographic and clinical features of IgAV and a control group were recorded into a predefined protocol. Disease activity was categorized as "remission" or "active" according to Birmingham Vasculitis Activity Score (BVAS). BVAS ≥ 1 was accepted as "active". Serum neopterin levels, high-sensitivity C-reactive protein (hsCRP) and IMA were evaluated according to BVAS and compared to the healthy control group.

RESULTS

Serum median (interquartile range) neopterin, IMA levels and hsCRP were higher in the study group than in control group (2.01 [12.5] ng/mL vs 1.77 [1.37] ng/mL, 0.67 [0.2] ng/mL vs. 0.43 [0.17] ng/mL, 5.6 [17.1] mg/L vs. 1.55 [1.6] mg/L, P = .095, P < .001 and P = .002, respectively). When evaluated according to BVAS, IMA and hsCRP levels were significantly higher in the group with active disease (0.77 [0.12] vs 0.61 [0.13] and 14.85 [4.6], P = .009 and P = .03, respectively). Serum neopterin levels were significantly higher in the active group compared to BVAS (18.95 [32.36] vs 1.63 [1.48], P < .001).

CONCLUSION

Oxidative stress is important in IgAV pathogenesis. Roles of hsCRP, neopterin and IMA as potential markers of diagnosis and disease activity seem to be worth studying in future studies with larger study groups.

An integrated portable system for single chip simultaneous measurement of multiple disease associated metabolites

Metabolites, the small molecules that underpin life, can act as indicators of the physiological state of the body when their abundance varies, offering routes to diagnosis of many diseases. The ability to assay for multiple metabolites simultaneously will underpin a new generation of precision diagnostic tools. Here, we report the development of a handheld device based on complementary metal oxide semiconductor (CMOS) technology with multiple isolated micro-well reaction zones and integrated optical sensing allowing simultaneous enzyme-based assays of multiple metabolites (choline, xanthine, sarcosine and cholesterol) associated with multiple diseases. These metabolites were measured in clinically relevant concentration range with minimum concentrations measured: 25 μM for choline, 100 μM for xanthine, 1.25 μM for sarcosine and 50 μM for cholesterol. Linking the device to an Android-based user interface allows for quantification of metabolites in serum and urine within 2 min of applying samples to the device. The quantitative performance of the device was validated by comparison to accredited tests for cholesterol and glucose.

The LDL/HDL ratio and atherosclerosis in ankylosing spondylitis

OBJECTIVES

In ankylosing spondylitis (AS) patients, cardiac and vascular involvement may manifest as atherosclerosis and coronary artery disease. Systemic inflammation, oxidative stress, increased low-density lipoprotein (LDL) cholesterol and decreased high-density lipoprotein (HDL) cholesterol constitute a significant risk for atherosclerosis. This study investigated the relationship between carotid intima-media thickness (CIMT), LDL/HDL ratio, total oxidant status (TOS; an indicator of oxidative stress) and ischemic modified albumin (IMA; an ischemic marker in AS patients).

PATIENTS AND METHODS

Sixty AS patients were diagnosed using the Modified New York Criteria; 54 age- and gender-matched participants were included as controls. CIMT, LDL/HDL ratio, TOS and IMA were measured using the most appropriate methods.

RESULTS

IMA was higher in AS patients compared to controls (p < 0.0001). TOS was also increased in AS patients (p = 0.005); as was CIMT (p < 0.0001). The LDL/HDL ratio was also greater in AS patients compared to controls (p = 0.047). A positive correlation was found between CIMT and LDL/HDL ratio among AS patients.

CONCLUSION

Elevated CIMT, IMA and TOS levels suggest an increased risk of atherosclerotic heart disease in AS patients. The LDL/HDL ratio was higher in AS patients compared to controls, and there was a correlation between LDL/HDL ratio and CIMT, albeit statistically weak. Therefore, the LDL/HDL ratio is not a reliable marker to predict atherosclerotic heart disease in AS patients.

Association of plasma xanthine oxidoreductase activity with severity and clinical outcome in patients with chronic heart failure

BACKGROUND

Oxidative stress due to purine degradation is associated with the development of chronic heart failure (CHF). Xanthine oxidoreductase (XOR) is a rate-limiting enzyme of purine degradation that plays a key role in uric acid (UA) production with a resultant increase in reactive oxygen species. However, the relationship between plasma XOR activity and CHF severity and clinical outcome remains unclear.

METHODS AND RESULTS

We measured XOR activity in 440 patients with CHF and 44 control subjects. Abnormally high and low XOR activities were identified based on the results for 95% of the control subjects (high and low XOR activities ≥120 and <33pmol/100μL/h, respectively). The prevalence rates of high and low XOR activities increased with advancing New York Heart Association functional class. There were 158 cardiac events during a median follow-up period of 1034days. Multivariate Cox proportional hazard regression analysis showed that both high and low XOR activities were significantly associated with cardiac events in patients with CHF after adjustment for confounding risk factors including serum UA and loop diuretic use. Kaplan-Meier analysis revealed that the cardiac event rate was significantly higher in patients with either high or low XOR activity. The net reclassification index was significantly improved by adding XOR activity to the basic risk factors.

CONCLUSIONS

We provide the first evidence of an association of plasma XOR activity with CHF severity and clinical outcome. Plasma XOR activity could be used to identify high-risk CHF patients and could be a therapeutic target for XOR inhibitors.

Impact of single anaerobic exercise on delayed activation of endothelial xanthine oxidase in men and women

OBJECTIVES

The aim of the study was to evaluate the activity of xanthine oxidase (XO) in the blood of men and women during the first hour following a single anaerobic exercise (AN-EX), and after 24 hours of recovery, and to determine whether the changes in XO activity in the blood after AN-EX are dependent on anaerobic performance.

METHODS

Ten men and ten women performed a single AN-EX. Blood was collected before and five times after completion of the AN-EX. The activity of XO was determined.

RESULTS

In both groups, a significant (P < 0.05) increase in blood XO activity was found only 24 hours after the AN-EX. The increased activity of XO in men was significantly lower than in women (P < 0.05). Negative correlations were found between the increase in XO activity in the blood plasma 24 hours after the AN-EX and anaerobic power, the total work performed during the AN-EX and the power decrease.

DISCUSSION

In the first hour after the single AN-EX, XO activity in the blood of women and men did not change, but after 24 hours of recovery, it was significantly higher compared to baseline levels in both sexes. Single AN-EX causes a smaller increase in XO activity in people with higher anaerobic performance.

The LDL/HDL ratio and atherosclerosis in ankylosing spondylitis

OBJECTIVES

In ankylosing spondylitis (AS) patients, cardiac and vascular involvement may manifest as atherosclerosis and coronary artery disease. Systemic inflammation, oxidative stress, increased low-density lipoprotein (LDL) cholesterol and decreased high-density lipoprotein (HDL) cholesterol constitute a significant risk for atherosclerosis. This study investigated the relationship between carotid intima-media thickness (CIMT), LDL/HDL ratio, total oxidant status (TOS; an indicator of oxidative stress) and ischemic modified albumin (IMA; an ischemic marker in AS patients).

PATIENTS AND METHODS

Sixty AS patients were diagnosed using the Modified New York Criteria; 54 age- and gender-matched participants were included as controls. CIMT, LDL/HDL ratio, TOS and IMA were measured using the most appropriate methods.

RESULTS

IMA was higher in AS patients compared to controls (p < 0.0001). TOS was also increased in AS patients (p = 0.005); as was CIMT (p < 0.0001). The LDL/HDL ratio was also greater in AS patients compared to controls (p = 0.047). A positive correlation was found between CIMT and LDL/HDL ratio among AS patients.

CONCLUSION

Elevated CIMT, IMA and TOS levels suggest an increased risk of atherosclerotic heart disease in AS patients. The LDL/HDL ratio was higher in AS patients compared to controls, and there was a correlation between LDL/HDL ratio and CIMT, albeit statistically weak. Therefore, the LDL/HDL ratio is not a reliable marker to predict atherosclerotic heart disease in AS patients.

Ischemia-Modified Albumin and Atherosclerosis in Patients With Familial Mediterranean Fever

The constriction of vessels due to atherosclerotic lesions causes hypoxia/ischemia and oxidative changes resulting in transformation of free albumin to ischemia-modified albumin (IMA) in the circulation and increased carotid intima–media thickness (cIMT). We investigated the reliability of IMA increase in evaluating atherosclerosis in patients with familial Mediterranean fever (FMF) compared with cIMT. Patients with FMF (n = 58) diagnosed by the Tel-Hashomer criteria in attack-free period and 38 healthy people were included in the study. Patient demographics as well as the clinical and laboratory characteristics of the healthy controls and patients with FMF were noted. The IMA levels and cIMT in patients with FMF were 0.30 ± 0.09 absorbance units (ABSUs) and 1.12 ± 0.27 mm, respectively, and in the control group, IMA levels and cIMT were 0.25 ± 0.07 ABSU and 0.74 ± 0.26 mm, respectively. The IMA levels and cIMT were significantly higher in patients with FMF than in controls ( P = .020 and P < .0001, respectively). The IMA values showed positive correlation with cIMT in patients with FMF( r = .302, P = .041). Our results reveal that IMA—an oxidative stress marker—may be an indicator of atherosclerosis in patients with FMF. This finding deserves further investigation.