Cerebrospinal fluid and serum uric acid levels in patients with multiple sclerosis

Background: Serum uric acid (UA), a natural scavenger of peroxynitrite, has been found to be of lower levels in patients with multiple sclerosis (MS) in some recent preliminary studies.Objective: To evaluate the correlation between serum UA levels and several clinical parameters of MS reliably.Methods: We surveyed studies on the serum UA levels and MS patients with comprehensive search and review of the references. A meta-analysis was performed to demonstrate the potential association between serum UA levels in MS patients and their clinical characteristics by random effects models.Results The serum UA levels were lower in patients with MS than in healthy controls (standardized mean difference (SMD) = −0·68; 95% confidence interval (CI): −0·82 to −0·55), as well as in other inflammatory neurological diseases (OINDs) (SMD = −0·45; 95% CI: −0·60 to −0·30). Similarly, the serum UA levels decreased in MS patients with clinical activity when compared to MS with clinical inactivity (SMD = −0·29; 95% CI: −0·48 to −0·10), as well as in relapsing–remitting MS (RRMS) patients with relapse in comparison to RRMS patients with remission (SMD = 0·64; 95% CI: 0·39 to 0·89). However, the results suggested that serum UA levels did not correlate with higher (or lower) expanded disability status scale (SMD = −0·09; 95% CI: −0·10 to 0·27) and magnetic resonance imaging (MRI) activity (SMD = −0·14; 95% CI: −0·13 to 0·41). In the subtypes of MS group, there were significant differences in serum UA levels between secondary progressive MS (SPMS) and RRMS (SMD = −0·34; 95% CI: 0·16 to 0·52), or primary progressive MS (PPMS) (SMD = −0·58; 95% CI: −0·89 to −0·27), but no significant difference between RRMS and PPMS (SMD = −0·18; 95% CI: −0·44 to 0·08).Conclusions: Our study suggests that UA is relevant to MS. Future research is needed to determine whether the administration of UA levels by inosine might be considered as a novel treatment strategy for MS.

Aim: Multiple sclerosis (MS) is an inflammatory demyelinating disease with unknown origin. Several studies suggest lower levels of serum uric acid (UA), an endogenous antioxidant, in MS patients. Methods: In this study, we aimed to investigate serum UA levels in relapsing-remitting (RR) MS. In addition we compared serum UA levels by means of clinical activity, expanded disability status scale (EDSS) and disease duration. Results: In the present study, mean serum UA levels were lower in RRMS and relapse patients with MS than in the other neurological diseases (OND) group, but the difference did not reach significance level. UA levels did not correlate with clinical activity, EDSS score and disease duration either in relapse or remitting or both of them. Conclusion: In conclusion, this study suggests serum uric acid levels may affect neither pathogenesis of MS nor activity of disease. Further studies are needed to clarify the role of uric acid in MS patients.

Background Prognostic impact of serum uric acid (UA) levels in patients with heart failure (HF) remains to be fully elucidated, as previous studies were inconclusive with small study sample sizes. Furthermore, although the J-curve relationship between serum UA levels and cardiovascular events has been suggested in patients with hypertension and those with diabetes, it is still unclear whether this is also the case for patients with HF. Purpose We examined the prognostic impacts of serum UA levels in HF patients, using the database of our Chronic Heart Failure Registry and Analysis in the Tohoku district (CHART)-2 Study, the largest multicenter, prospective, observational cohort study for cardiovascular patients with HF or those at risk of HF in Japan (N=10,219). Methods First, we determined the cut-off value of serum UA levels at baseline by the Classification and Regression Tree (CART). Then, we divided 4,652 consecutive HF patients in the CHART-2 Study into 4 groups; G1 (<3.8 mg/dL, N=313), G2 (3.8–7.1 mg/dL, N=3,070), G3 (7.2–9.2 mg/dL, N=1,018), and G4 (≥9.3 mg/dL, N=251). Among the 4 groups, we compared clinical characteristics and incidence of all-cause death, HF hospitalization, and a composite of all-cause death and HF hospitalization. Results Mean age in G1, G2, G3, and G4 was 71±12, 69±12, 68±13, and 69±15 years, respectively (P<0.001). G1 was characterized by a significantly high prevalence of women as compared with G2, G3 and G4 (59, 32, 24 and 23%, respectively). Serum creatinine levels (0.8±0.4, 0.9±0.4, 1.2±0.6 and 1.4±0.8 mg/dL, respectively), prevalence of atrial fibrillation (34, 39, 45 and 50%, respectively), and diuretics use (36, 45, 67, 89%, respectively) increased from G1, G2, G3 to G4 (all P<0.001), while left ventricular ejection fraction decreased from G1, G2, G3 to G4 (59±15, 58±15, 54±15, and 52±17%, respectively, P<0.001). Median BNP levels were comparably low in G1 and G2 and then increased to G3 and G4 (94.4, 91.5, 130 and 192.5 pg/mL, respectively, P<0.001). As a HF etiology, prevalence of ischemic heart disease was highest in G2 and lowest in G4 (48, 52, 48, 38%, respectively, P<0.001), while that of dilated cardiomyopathy increased from G1, G2, G3 to G4 (11, 12, 16 and 20%, respectively, P<0.001). During the median follow-up period of 6.3 years, in G1, G2, G3 and G4, 111 (35%), 905 (29%), 370 (36%) and 139 (55%) patients died and 79 (25%), 729 (24%), 300 (29%) and 115 (46%) experienced HF hospitalization, respectively (both P<0.001). Cox proportional hazard models adjusted for clinical backgrounds showed that, as compared with G2, both G1 and G4 had increased risk for all-cause death, HF hospitalization and a composite of all-cause death, and HF hospitalization, indicating the J-curve relationship between serum UA levels and prognosis (Figure). Prognostic impacts of serum UA levels Conclusions Both decreased and increased UA levels were associated with increased incidence of death and HF hospitalization in HF patients.

Effectiveness of a single fixed dose of rasburicase 3 <scp>mg</scp> in the management of tumour lysis syndrome

BackgroundSerum uric acid (UA) could exert neuro-protective effects against Alzheimer's disease (AD) via its antioxidant capacities. Many studies investigated serum UA levels in AD patients, but to date, results from these observational studies are conflicting.MethodsWe conducted a meta-analysis to compare serum UA levels between AD patients and healthy controls by the random-effects model. Studies were identified by searching PubMed, ISI Web of Science, EMBASE, and the Cochrane library databases from 1966 through July 2013 using the Medical Subject Headings and keywords without restriction in languages. Only case-control studies were included if they had data on serum UA levels in AD patients and healthy controls. Begg's funnel plot and Egger's regression test were applied to assess the potential publication bias. Sensitivity analyses and meta-regression were conducted to explore possible explanations for heterogeneity.ResultsA total of 11 studies met the inclusion criteria including 2708 participants were abstracted. Serum UA levels were not significantly different in AD patients compared to healthy controls (standardized mean difference (SMD) = −0.50; 95% confidence interval (CI): −1.23 to 0.22). Little evidence of publication bias was observed. Sensitivity analyses showed that the combined SMD was consistent every time omitting any one study, except only one study which greatly influenced the overall results. Meta-regression showed that year of publication, race, sample size, and mean age were not significant sources of heterogeneity.ConclusionOur meta-analysis of case-control studies suggests that serum UA levels do not differ significantly in AD patients, but there may be a trend toward decreased UA in AD after an appropriate interpretation. More well-designed investigations are needed to demonstrate the potential change of serum UA levels in AD patients.

This study assessed the relationship between the progression of Parkinson's disease (PD) with cognitive impairment and changes in serum uric acid (UA) and homocysteine (Hcy) concentrations and explored the factors influencing PD with cognitive impairment. The study randomly selected 74 patients with PD and evaluated their cognitive function using the Montreal Cognitive Assessment Scale (MoCA). Patients with PD were divided into two subgroups: those with and without cognitive impairment. PD severity was evaluated and graded using the Hoehn and Yahr (H-Y) scale. Another 60 middle-aged and older individuals without PD during the same period were selected as a control group. Blood UA and Hcy concentrations in each group were measured to assess the relationship between PD, cognitive impairment, and changes in UA and Hcy concentrations. The PD group with cognitive impairment had a lower UA concentration and higher Hcy concentration. The UA concentration was significantly higher in the early PD stages than in the middle and late stages (P<0.05). A significant negative relationship between MoCA scores and serum UA levels was found in patients with PD, whereas a positive relationship existed between MoCA scores and serum Hcy concentrations. Regression analysis showed that a higher UA concentration was an independent protective factor for PD with cognitive impairment, while a higher Hcy concentration was a risk factor (P<0.05). A serum UA concentration of 212.9 mmol/L and Hcy concentration of 13.35 mmol/L could distinguish between patients with PD with or without cognitive impairment with a sensitivity of 93.2% and specificity of 43.3%. PD and cognitive impairment were associated with a decrease in UA concentration; the later the H-Y stage was, the lower the UA concentration was. The increase in Hcy concentration was related to PD and its cognitive impairment, whereas it is not significantly correlated with PD progression.

It is unclear whether Serum Uric Acid (SUA) promotes or protects against cerebrovascular disease. Present study was done to estimate uric acid levels and its association in patients of acute ischemic stroke. Method: Total 100 consecutive patients (50 males and 50 females) with first episode of stroke as evidenced by CT scan within 48 hours were chosen for the study .The serum uric acid was estimated by the Uricase method. The patients were further evaluated for the presence of additional risk factors like hypertension, diabetes mellitus, coronary heart disese (CAD),smoking and alcoholism. Results: Out of total 100 patients, 50 were males and 50 were females. The age of the patients in the present study were from 40 years to 84 years with mean age of 59.8 years. Mean serum uric acid level in patients were studied 5.58±1.68 mg/dl and about 25% patients were hyperuricemic. As age advances the uric acid level also rised with the ' p ' of < 0.001. Among diabetics the mean uric acid value was 6.12± 1.64 mg/dl while among non diabetics it was 5.02± 1.54 mg/dl, among in CAD patients it was 6.5± 1.9 mg/dl and in those without CAD was 5.1 ± 1.4 mg/dl; Among the patients with large infarct was 7.2 mg/dl compared to those with small infarct was 4.816 mg/dl and thus established a statistically significant relationship (p value of < 0.0001). The present study didnt show any significant association between hypertension, hyperlipidemia, smoking, alcoholism and uric acid. Conclusions: The prevalence of hyperuricemia in acute ischemic stroke patients in the present study was 25%. There was a statistically significant association between levels of uric acid and age, diabetes mellitus, CAD, larger infarct size. There was no stastically a signicant association between hypertension, hyperlipidemia, smoking, alcoholism and uric acid levels.

Uric acid (UA) is a purine metabolite that selectively inhibits peroxynitrite-mediated reactions implicated in the pathogenesis of multiple sclerosis (MS) and other neurodegenerative diseases. Serum UA levels are inversely associated with the incidence of MS in humans because MS patients have low serum UA levels and individuals with hyperuricemia (gout) rarely develop the disease. Moreover, the administration of UA is therapeutic in experimental allergic encephalomyelitis (EAE), an animal model of MS. Thus, raising serum UA levels in MS patients, by oral administration of a UA precursor such as inosine, may have therapeutic value. We have assessed the effects of inosine, as well as inosinic acid, on parameters relevant to the chemical reactivity of peroxynitrite and the pathogenesis of EAE. Both had no effect on chemical reactions associated with peroxynitrite, such as tyrosine nitration, or on the activation of inflammatory cells in vitro. Moreover, when mice treated with the urate oxidase inhibitor potassium oxonate were fed inosine or inosinic acid, serum UA levels were elevated markedly for a period of hours, whereas only a minor, transient increase in serum inosine was detected. Administration of inosinic acid suppressed the appearance of clinical signs of EAE and promoted recovery from ongoing disease. The therapeutic effect on animals with active EAE was associated with increased UA, but not inosine, levels in CNS tissue. We, therefore, conclude that the mode of action of inosine and inosinic acid in EAE is via their metabolism to UA.

Is there a relationship between serum uric acid and fructose levels in polycystic ovary syndrome (PCOS)? Elevated serum uric acid levels in women with PCOS positively correlate with serum fructose levels, and elevated serum fructose levels are an independent risk factor for hyperuricemia in women with PCOS. Our previous study suggested a link between elevated serum fructose levels and PCOS. Fructose is unique as it generates uric acid during metabolism, and high uric acid levels are associated with metabolic disorders and an increased risk of anovulation. However, the relationship between serum uric acid and fructose levels in women with PCOS remains unclear. In a case-control study of 774 women (482 controls and 292 patients with PCOS) between May and October 2020 at the Shengjing Hospital of China Medical University, the relationship between uric acid and fructose levels in women with PCOS was examined. Participants were divided into subgroups based on various factors, including BMI, insulin resistance, dyslipidemia, metabolic syndrome, and hyperuricemia. Serum uric acid concentrations were measured using enzymatic assays, and serum fructose levels were determined using a fluorescent enzyme immunoassay. Dietary fructose data were collected through a validated food-frequency questionnaire of 81 food items. We applied restricted cubic splines to a flexibly model and visualized the linear/nonlinear relationships between serum uric acid and fructose levels in PCOS. Multivariate logistic analysis was executed to assess the association between serum fructose levels and hyperuricemia in PCOS. Human granulosa cell and oocyte mRNA profile sequencing data were downloaded for mapping uric acid and fructose metabolism genes in PCOS. Further downstream analyses, including Gene Ontology, Kyoto Encyclopedia of Genes and Genomes analysis, and protein-protein interactions were then carried out on the differentially expressed genes (DEGs). The correlation between uric acid and fructose metabolism genes was calculated using the Pearson correlation coefficient. The GeneCards database was used to identify DEGs related to uric acid and fructose metabolism in PCOS, and then several DEGs were confirmed by quantitative real-time PCR. Both serum fructose and uric acid levels were significantly increased in women with PCOS compared with the control women (P < 0.001), and there was no statistically significant difference in dietary fructose intake between PCOS and controls, regardless of metabolic status. There was a positive linear correlation between serum uric acid and fructose levels in women with PCOS (Poverall < 0.001, Pnon-linear = 0.30). In contrast, no correlation was found in control women (Poverall = 0.712, Pnon-linear = 0.43). Additionally, a non-linear association was observed in the obese subgroup of patients with PCOS (Poverall < 0.001, Pnon-linear = 0.02). Serum uric acid levels were linearly and positively associated with serum fructose levels in patients with PCOS with insulin resistance, dyslipidemia, and metabolic syndrome. Furthermore, even after adjusting for confounding factors, elevated serum fructose levels were an independent risk factor for hyperuricemia in patients with PCOS (P = 0.001; OR, 1.380; 95% CI, 1.207-1.577). There were 28 uric acid and 25 fructose metabolism genes which showed a significant correlation in PCOS. Seven upregulated genes (CAT, CRP, CCL2, TNF, MMP9, GCG, and APOB) related to uric acid and fructose metabolism in PCOS ovarian granulosa cells were ultimately successfully validated using quantitative real-time PCR. Due to limited conditions, more possible covariates (such as smoking and ethnicity) were not included, and the underlying molecular mechanism between fructose and uric acid levels in women with PCOS remains to be further investigated. The results of this study and our previous research indicate that the high uric acid status of PCOS may be mediated by fructose metabolism disorders, highlighting the importance of analyzing fructose metabolism, and especially its metabolic byproduct uric acid, during the clinical diagnosis of PCOS. These results suggest the adverse effects of high uric acid in PCOS, and the importance of taking early interventions regarding uric acid levels to reduce the occurrence and development of further clinical signs, such as metabolic disorders in women with PCOS. This work was supported by: the National Natural Science Foundation of China (No. 82371647, No. 82071607, and No. 32100691); LiaoNing Revitalization Talents Program (No. XLYC1907071); Fok Ying Tung Education Foundation (No. 151039); and Outstanding Scientific Fund of Shengjing Hospital (No. 202003). No competing interests were declared. N/A.

Objective To reveal the relationship between uric acid level and carotid atherosclerotic plaques in hypertensive subjects in randomized urban population according to 10-years prospective study. Design and methods A 10-years prospective study included 3,500 randomized individuals living in the district of Vitebsk (2007/2008 - 2017/2018). The coverage of the survey was 97,9% (3427 participants). There was revealed 2170 persons with normal blood pressure. 1862 of them were examined on the second stage in 2012/2013 (coverage of the survey was 85,8%). 286 new cases of hypertension were revealed and they had significant positive relationship with the IV quartile of uric acid level (≥339 μmol/l). A 10-years prospective analysis was provided in 2017/2018 and included 145 randomized subjects with hypertension diagnosed on the second stage of the study. Specially developed registration form was filled in for all the participants and it included socio-demographic data, standard questionnaires for detection of cardiovascular risk factors, anthropometry, blood pressure measurements, electrocardiography, blood chemistry, ultrasound examination of brachiocephalic arteries and echocardiography. Results According to the results of 10-years prospective study serum uric acid level ≥339 μmol/l, revealed at the start of the study, is a predictor of the detection of carotid atherosclerotic plaques in 2017/2018 in subjects with new cases of hypertension (df=1; χ2 Wald=6,63; p&amp;lt;0,05) adjusted for age and gender. Cross-sectional analysis of these subjects showed that the level of uric acid, regardless of age and gender, is associated with the level of triglycerides (p&amp;lt;0,001), apo B (p&amp;lt;0,001), apo A1 (p&amp;lt;0,05), LDL (p&amp;lt;0,05), VLDL (p&amp;lt;0,05), HDL (p&amp;lt;0,05), non-HDL-C (p&amp;lt;0,05), total cholesterol (p&amp;lt;0,05), high-sensitivity CRP (p&amp;lt;0,05), TNF-α (p&amp;lt;0,05), apoB/apoA1 ratio (p&amp;lt;0,05), glycated hemoglobin percentage (p&amp;lt;0,05), body mass index (p&amp;lt;0,001), waist circumference (p&amp;lt;0,05), metabolic syndrome (p&amp;lt;0,05) and alcohol abuse (p&amp;lt;0,05). In stepwise multiple linear regression model the most significant of these factors were the level of triglycerides (β=0,23, p&amp;lt;0,05), alcohol abuse (β=0,18, p&amp;lt;0,05), body mass index (β=0,18, p&amp;lt;0,05), apoB/apoA1 ratio (β=0,17, p&amp;lt;0,05) and level of high-sensitivity CRP (β=0,15, p&amp;lt;0,05). Conclusions Serum uric acid level ≥339 μmol/l predicted detection of carotid atherosclerotic plaques in patients with new cases of hypertension in 10-years prospective study. The most significant factors, regardless of age and gender, associated with serum uric acid levels in these patients were level of triglycerides, alcohol abuse, body mass index, apoB/apoA1 ratio and level of high-sensitivity C-reactive protein. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Republican Scientific and Practical Centre of Cardiology

Uric acid (UA), the final product of purine metabolism, has been reported to be reduced in patients with various neurological disorders and is considered to be a possible indicator for monitoring the disability and progression of multiple sclerosis. However, it remains unclear whether there is a close relationship between UA and myasthenia gravis (MG), or whether UA is primarily deficient or secondarily reduced because of its peroxynitrite scavenging activity. We investigated the correlation between serum UA levels and the clinical characteristics of MG. We assessed 338 serum UA levels obtained in 135 patients with MG, 47 patients with multiple sclerosis, and 156 healthy controls. In addition, we compared serum UA levels when MG patients were stratified according to disease activity and classifications performed by the Myasthenia Gravis Foundation of America, age of onset, duration, and thymus histology (by means of MRI or computed tomography). MG patients had significantly lower serum UA levels than the controls (P<0.001). Moreover, UA levels in patients with MG were inversely correlated with disease activity and disease progression (P=0.013). However, UA levels did not correlate significantly with disease duration, age of onset, and thymus histology. Our findings suggest that serum level of UA was reduced in patients with MG and serum UA might be considered a surrogate biomarker of MG disability and progression.

BackgroundIn recent years, emerging evidence has suggested that ulcerative colitis occurs as a consequence of an imbalance between oxidative stress and antioxidant capacity. The objective of this study was to investigate whether serum total bilirubin and serum uric acid levels were associated with ulcerative colitis.Material/MethodsWe conducted a retrospective case-control study which included 170 patients with ulcerative colitis and 200 healthy individuals. Concentrations of serum total bilirubin and serum uric acid were obtained from biochemical information and segregated into quartiles. Logistic regression analysis was adopted to explore the correlations between levels of the 2 biochemical markers and the risk of ulcerative colitis.ResultsCompared with healthy controls, patients with ulcerative colitis exhibited lower levels of serum bilirubin (9.30 umol/L versus 12.49 umol/L respectively, P<0.001). Multivariate logistic regression showed that the lowest quartile of total serum bilirubin was independently associated with the occurrence of ulcerative colitis (OR=2.56, 95%CI: 1.54–4.25, P<0.001). Similarly, ulcerative colitis patients exhibited higher concentrations of serum uric acid (338 umol/L versus 300 umol/L respectively, P=0.041). Multivariate logistic regression showed that the highest quartile of serum uric acid was independently associated with ulcerative colitis risk (OR=1.20, 95%CI: 1.05–1.77, P=0.045). Furthermore, a negative association was observed between serum total bilirubin and serum uric acid in patients with ulcerative colitis.ConclusionLower levels of serum total bilirubin and higher levels of serum uric acid are associated with ulcerative colitis patients compared to healthy controls.

BackgroundElevated triglyceride (TG) levels are a biomarker for cardiovascular disease (CVD) risk. The correlation between serum uric acid (SUA) and TG concentrations in adults or obese children is well established. However, studies on SUA and TG in children with short stature are limited.AimTo determine the relationship between SUA and TG levels in short children and adolescents.MethodThis was a cross-sectional evaluation of a cohort of 1095 patients with short stature (720 males and 375 females). The related clinical characteristics, including anthropometric and biochemical parameters, were determined.ResultsSmooth curve fitting, adjusted for potential confounders was performed, which indicated the existence of a non-linear relationship between these measures. Piecewise multivariate linear analysis revealed a significant positive relationship between SUA and TG at SUA concentrations over 7 mg/dL (β = 0.13, 95% CI: 0.05–0.22, P = 0.002) but no significant correlation at lower SUA levels (β = 0.01, 95% CI: 0.01–0.04, P = 0.799). Furthermore, a stratified analysis was performed to appraise changes in this relationship for different sexes and standard deviation levels of body mass index (BMI). The non-linear relationship remained consistent in males and females with BMI standard deviation scores (BMI SDS) ≥ 0, with inflection points of 6.71 mg/dL and 3.93 mg/dL, respectively. Within these two groups, SUA and TG levels showed a positive association when SUA levels were higher than the inflection point (β = 0.21, 95% CI: 0.11–0.31, P < 0.001 for males and β = 0.1, 95% CI: 0.03–0.17, P = 0.005 for females). However, a specific relationship was not observed at lower SUA levels. No significant relationships were found between SUA and TG levels in males and females with BMI SDS < 0.ConclusionThe present study identified the non-linear association of SUA and TG levels with short children and adolescents. This relationship was based on BMI status. This finding suggests that health status should be considered for short stature children with high SUA levels, especially in children with a high BMI standard deviation score.

ObjectiveThe association between Parkinson's disease (PD) and uric acid levels has gained intensive interest in recent years. We applied meta-analysis to investigate serum uric acid levels in patients with PD...

Objectives: In this study, we aimed to compare serum uric acid levels in patients diagnosed with antisocial personality disorder with a healthy control group, and also to investigate the relationship between serum uric acid levels and impulsivity and aggressive attitudes. Methods: The study was conducted with 126 individuals (69 with antisocial personality disorder, 57 controls). The Sociodemographic Data Form, the Barratt Impulsivity Scale (BIS-11), and the Buss–DurkeeHostility Inventory (BDHI) were applied to all participants. Venous blood samples were collected from all participants to measure serum uric acid levels. Results: It was determined that both the BIS-11 and the BDHI sub-dimensions, and the total scores of the antisocial personality disorder patients were higher when compared to the healthy control group. The serum uric acid levels of the patient group were significantly higher when compared to those of the control group. Furthermore, there was a significant positive correlation between serum uric acid level and Barratt Impulsivity Scale–11 (r=0.635, P &lt; .001) and Buss–Durkee Hostility Inventory (r=0.572, P &lt; .001) scores. Conclusion: In our study, it was found that serum uric acid levels were higher in patients with antisocial personality disorder, which is characterized by impulsivity and aggressive behavior, when compared to the control group. The findings of the present study suggest that purinergic dysfunction may also play a role in the etiopathogenesis of the disease. Further studies are required to determine whether this was a cause or an outcome. Cite this article as: Yıldız S, Kazğan A, Kurt O, Korkmaz S, Uğur K. The correlation between serum uric acid level and certain clinical variables in antisocial personality disorder patients. Neuropsychiatr Invest. 2021;59(2):45-52.