What does serum γ-glutamyltransferase tell us as a cardiometabolic risk marker?

Serum γ-glutamyltransferase levels and obesity status changes the risk of prehypertension in Chinese adults

Objective

It's well known that γ-Glutamyltransferase (γ-GGT) and obesity plays an important role in the development of preHT. However, the effect of γ-GGT on preHT in populations with different obesity status remains unclear.

Methods

From February 2014 to January 2018, a total of 20,368 participants were enrolled in this study after excluding those with hypertension and liver diseases. Fasting blood samples were collected to measure γ-GGT and blood lipid levels and glucose indices. Demographic and clinical parameters such as sex, age, height, weight, neck circumference (NC), waist circumference (WC), hip circumference (HC), and body fat ratio (BFR); and information on smoking and alcohol consumption were collected by trained medical professionals.

Results

Participants were divided into three groups based on obesity status. The prevalence of preHT was 83.5 % in the obesity group was higher than that in the overweight group (58.9 %) and the normal group (47.1 %). γ-GGT in different categories of obesity indices were significantly different, and higher obesity indices were found with higher γ-GGT levels. The interaction of γ-GGT and obesity indices such as NC, WC, HC, and BFR on the prevalence of preHT was significant (P = 0.028, 0.002, 0.007, and 0.034, respectively). Serum γ-GGT was found to be positively associated with preHT in participants with normal and overweight body mass indices.

Conclusion

Our results indicate that γ-GGT is a risk factor for preHT in participants who are nonobese, and that the obesity indices NC, WC, HC, BFR, and γ-GGT were contributing factors in increasing the risk of preHT.

Serum Gamma Glutamyltransferase: A Biomarker for Identifying Postprandial Hypertriglyceridemia

Purpose

Elevated serum gamma-glutamyltranspeptidase (GGT) is an independent marker of the activation of systemic inflammation, while conditions associated with elevated triglyceride (TG) levels, such as type 2 diabetes, non-alcoholic fatty liver disease, obesity, and metabolic syndrome, are associated with an increased inflammatory burden. Moreover, serum liver enzymes (GGT, alanine aminotransferase [ALT], aspartate aminotransferase [AST], and alkaline phosphatase [ALP]) are associated with metabolic syndrome and its components, including hypertriglyceridemia. However, the relationship between liver enzymes and postprandial hypertriglyceridemia (PHTG) remains unclear. Therefore, in this study we conducted oral fat tolerance tests (OFTTs) to understand the differences in serum liver enzyme levels among individuals with different lipid tolerance levels and their correlation with PHTG.

Patients and Methods

 For the OFTT, we enrolled 202 non-diabetic volunteers whose fasting triglyceride (TG) levels were less than 1.7 mmol/L in this case-control study. The participants were categorized into two groups according to the TG levels at the 0- and 4-h OFTT: a postprandial normal TG (PNTG) group and a PHTG group. Routine fasting serum biochemical indices, liver enzyme (GGT, ALT, AST, and ALP) levels, and 0- and 4-h OFTT lipid levels were assessed.

Results

The PHTG group had significantly higher serum GGT and ALT levels and a lower AST/ALT ratio than those in the PNTG group. However, no significant difference was observed in AST and ALP levels compared with the PNTG group. After adjusting for major confounders, logistic regression analysis indicated a significant correlation between serum GGT and PHTG (odds ratio = 1.168, P < 0.001), but not with ALT level, AST level, AST/ALT ratio, and ALP level. The receiver operating characteristic curve analysis demonstrated that the serum GGT level was an effective predictor of PHTG.

Conclusion

Serum GGT levels are significantly associated with PHTG risk and serve as an effective biomarker for early identification.

Gamma-glutamyl transpeptidase and indirect bilirubin may participate in systemic inflammation of patients with psoriatic arthritis

BACKGROUND

Previous studies have suggested that systemic metabolic abnormalities are closely related to psoriatic arthritis (PsA). Gamma-glutamyl transpeptidase (GGT) and indirect bilirubin (IBIL), two essential active substances in hepatic metabolism that have been demonstrated as an oxidative and anti-oxidative factor respectively, have been proved to be involved in oxidative stress damage and inflammation in several human diseases. However, their role in PsA remains unclear.

METHODS

In this retrospective comparative cohort study, a case group of 68 PsA patients and a control group of 73 healthy volunteers from the Third Hospital of Hebei Medical University were enrolled. Serum GGT, IBIL, GGT/IBIL ratio and C-reactive protein (CRP), a well applied bio-marker of systemic inflammatory in PsA, were compared between the two groups. Furthermore, the relationship of GGT, IBIL and GGT/IBIL with CRP were explored in PsA patients. Finally, the patients were divided into high inflammation group and low inflammation group according to the median value of CRP. Multivariate logistic regression analyses were used for the association of systemic inflammation level with GGT, IBIL and GGT/IBIL.

RESULTS

Compared with healthy controls, PsA patients exhibited significantly higher serum GGT, GGT/IBIL, and CRP levels and lower IBIL levels. Serum GGT and GGT/IBIL were positively correlated with CRP, whereas IBIL were negatively correlated with CRP. Binary logistic regression analysis revealed that serum GGT was a risk factor for high CRP in PsA, whereas IBIL was a protective factor. Furthermore, GGT/IBIL was a better indicator of high CRP condition in PsA patients than either GGT or IBIL alone, as determined by the receiver operating characteristic curves.

CONCLUSION

GGT and IBIL may participate in the pathogenesis of PsA. Additionally, GGT, IBIL and the balance of the two may reflect systemic inflammation mediated by oxidative stress events related to metabolic abnormalities to a certain extent.

Gamma glutamyl transferase as a biomarker to predict contrast-induced nephropathy among patients with acute coronary syndrome undergoing coronary interventions: a meta-analysis

The third most frequent reason for hospitalized acute kidney injury is contrast-induced nephropathy (CIN). Percutaneous coronary intervention (PCI) and coronary angiography (CAG) are two interventions that can result in CIN. In this study, we sought to determine how well gamma-glutamyl transferase (GGT) can predict CIN following CAG and PCI.

METHOD

Two researchers searched through PubMed, Scopus, and Web of Science in November 2022 to find articles that examined GGT levels in CIN patients following PCI or CAG. To rate the quality of the studies, the Joanna Briggs Institute Critical Appraisal Checklist was employed. The Cochran test and I2 statistics were utilized to assess study heterogeneity. To calculate the number of participants required to reject the null hypothesis, power analysis was used. We evaluated the epidemiologic strength of the results using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). The authors used Comprehensive Meta-analysis Version 3 to summarize the results.

RESULTS

GGT was shown to be considerably greater in patients with CIN according to the meta-analysis's findings (odds ratio: 3.21, 95% CI: 1.26-8.15, P=0.014); nevertheless, the findings were accompanied by significant heterogeneity (I2=91.93%, P<0.001). Although the relationship between CIN and GGT was power full regarding power analysis (1- β =1, number of effect sizes=4, the average number per group=336), very low quality of evidence was observed regarding GRADE criteria.

CONCLUSIONS

These results suggest the GGT level may be a predictor of contrast-induced nephropathy in patients having cardiac catheterization; however, more research is required to prove the epidemiological validity.

Shear wave elastography to evaluate carotid artery elasticity in long-term drinkers with varying degrees of alcoholic fatty liver disease

OBJECTIVE

To evaluate carotid artery elasticity in long-term drinkers with varying degrees of alcoholic fatty liver disease (AFLD) by shear wave elastography (SWE).

METHODS

Of the 92 drinkers with alcohol drinking for greater than or equal to 5 years, were fell into three groups depending on the liver ultrasound results: group B (without AFLD), group C (with mild AFLD), and group D (moderate-to-severe AFLD). Another 32 healthy adults were selected as the control group (group A). All participants had no significant carotid plaque. Gray scale ultrasound and color doppler ultrasound were used to obtain the left common carotid peak systolic velocity (PSV), carotid diastolic internal diameter (D_d ), carotid intima-media thickness (IMT), carotid systolic internal diameter (D_s ) and the stiffness coefficient (β). Mean values of mean elastic modulus (ME_mean ), minimum elastic modulus (ME_min ), and maximum elastic modulus (ME_max ) of the anterior wall of the left common carotid artery at end-diastole were measured by SWE.

RESULTS

D_d , D_s , and PSV among the four groups showed no differences. (all P > 0.05). Compared with groups A and B, ME_min , ME_max , and ME_mean were significantly higher in group C (all P < 0.05), while IMT and β were not statistically different (all P > 0.05). ME_mean , ME_min , ME_max , IMT, and β were significantly higher in group D compared with the other three groups (all P < 0.05). No significant differences were observed in IMT, β, ME_mean , ME_max , and ME_min between groups A and B (all P > 0.05).

CONCLUSIONS

Shear wave elastography can provide a quantitative evaluation for the carotid artery elasticity in long-term drinkers with varying degrees of AFLD.

Gamma glutamyl transferases in association with cardiovascular risk scores in non-diabetic hypertensive Cameroonians: preliminary data from HYRICCA study

Objective

The usefulness of gamma glutamyl transferase (GGT) as biomarker of cardiovascular risk (CVR) remains unexplored in sub-Saharan Africans. To evaluate their relevance on CVR assessment in non-diabetic hypertensive Cameroonians. This was a prospective cross-sectional study on non-diabetic hypertensive adults aged 57.7 ± 10 years (62% female), without evidence of acute or chronic liver disease, in which we assessed GGT levels and correlates it with validated CVR biomarkers, CVR scores (WHO risk score, Framingham 2008, ASCVD 2013, EuroSCORE 2003, and Reynolds score), and plasma atherogenic index (PAI).

Results

We found a positive but weak association between GGT and PAI on linear regression [0.004 (0.001; 0.007); p = 0.021], which was dependent of triglycerides levels (r = 0.17; p = 0.03). We did not find a significant association between GGT levels and the results of the CVR scores studied; Although being related to atherogenic risk, as reported in literature in non-sub-Saharan Africans, GGTs would be of little value for CVR assessment in our population.

Can Gamma-glutamyl Transferase Predict Unhealthy Metabolic Phenotypes Among Healthcare Workers in Azar Cohort Study?

Background: Although various studies have assessed the correlation between gamma-glutamyl transferase (GGT) and cardiometabolic risk factors in obesity, no research has differentiated among metabolically-healthy obese (MHO) and metabolically unhealthy obese (MUHO), metabolically-healthy lean (MHL), and metabolically-unhealthy lean (MUHL). Objectives: Accordingly, this study evaluated the correlation between GGT and cardiometabolic phenotypes among healthcare workers. Methods: In this study, there were anthropometric measurements as well as the measurements of fasting blood sugar (FBS), GGT, cholesterol, triglyceride (TG), high lipoprotein density (HDL), and blood pressure in 1458 healthcare workers enrolled in the Azar Cohort Study. Metabolic syndrome (MetS) was defined according to the National Cholesterol Education Program Adult Treatment Panel III (ATP III). Accordingly, the participants were divided into four cardiometabolic phenotypes. Results: In this cross-sectional study, there was a significant difference in the prevalence of cardiometabolic phenotypes regarding the GGT tertiles (P ≤ 0.001). The highest prevalence of MHO was observed in the third GGT tertile. The mean waist circumference, TG, FBS, HDL, and systolic and diastolic blood pressure levels increased in the MHO, MUHO, and MHL groups in a dose dependent manner with an increase in the GGT tertiles (P < 0.05). In comparing the highest and lowest GGT tertile, the risk of MHO and MUHO increased by 2.84 (95%CI 2.01 - 4.01) and 9.12 (95%CI 5.54 - 15), respectively. However, the correlation between the GGT tertile and MUHL did not reveal a similar trend. The ROC curve shows the cutoff value of 18.5 U/L for GGT, which allowed us to distinguish between the MUHO and MHO individuals. Conclusions: The findings revealed that GGT can indicate the risk of MetS as such, it can be used to detect at-risk MHO individuals and administer proper interventions.

Multi-omics profiling of collagen-induced arthritis mouse model reveals early metabolic dysregulation via SIRT1 axis

Rheumatoid arthritis (RA) is characterized by joint infiltration of immune cells and synovial inflammation which leads to progressive disability. Current treatments improve the disease outcome, but the unmet medical need is still high. New discoveries over the last decade have revealed the major impact of cellular metabolism on immune cell functions. So far, a comprehensive understanding of metabolic changes during disease development, especially in the diseased microenvironment, is still limited. Therefore, we studied the longitudinal metabolic changes during the development of murine arthritis by integrating metabolomics and transcriptomics data. We identified an early change in macrophage pathways which was accompanied by oxidative stress, a drop in NAD+ level and induction of glucose transporters. We discovered inhibition of SIRT1, a NAD-dependent histone deacetylase and confirmed its dysregulation in human macrophages and synovial tissues of RA patients. Mining this database should enable the discovery of novel metabolic targets and therapy opportunities in RA.

Prevention of Hepatorenal Insufficiency Associated with Lead Exposure by Hibiscus sabdariffa L. Beverages Using In Vivo Assay

Lead pollution is a major environmental challenge worldwide. Therefore, dietary interventions that are aimed at preventing lead's deleterious effects on body organs are needed. The study's goal was to study and compare the protective effect of cold and hot beverages of Roselle (Hibiscus sabdariffa L.) red calyces (CRB and HRB, respectively) on liver and kidney insufficiency associated with lead exposure in male rats. Adult albino rats (32 males) were divided into four groups of equal number, including a normal control (group 1), while groups from 2 to 4 received lead acetate (20 mg/kg body weight/day) and were kept untreated (group 2). The 3rd and the 4th groups received CRB and HRB (0.5 ml/100 g body weight/day), respectively, for 6 weeks. The gain in the body and relative weights of the liver and kidneys were calculated. Liver and kidney functions were determined in serum, while lead, delta-aminolevulinic acid dehydratase, and oxidative stress markers were established in tissues. Specimens from the liver and kidney of sacrificed rats were histopathologically examined. The total activity of antioxidants and total content of anthocyanin of both beverages were determined. Lead exposure resulted in its accumulation in tissues, leading to overweight and liver and kidney insufficiency along with oxidative stress, which was further confirmed by histological staining. CRB was more efficient than HRB in preventing the deleterious effects of lead intoxication. Due to their antioxidant properties, the present study proved that Roselle red calyx beverages, particularly the cold ones, are protective agents against lead-associated disorders in a rat model.

Prevalence and Clinical Predictors of Hyperuricemia in Chinese Bariatric Surgery Patients

BACKGROUND

Despite a known significant association between hyperuricemia and obesity, this correlation in bariatric surgery patients remains unknown.

OBJECTIVES

To evaluate the prevalence and predictors of pre- and postoperative hyperuricemia in Chinese bariatric surgery patients.

METHODS

A retrospective study was performed in 333 bariatric surgery patients from our hospital. The clinical data was collected before surgery and at 3, 6, and 12 months postoperatively. Univariable and multivariate analyses were used for investigating the independent predictors of hyperuricemia and serum uric acid (SUA) change.

RESULTS

Altogether, 62.9% of patients fulfilled the diagnostic criteria for hyperuricemia. The prevalence of hyperuricemia among males was 81.8% and 62.3% in the women. Multiple logistic regression analyses showed that age (OR = 0.951, 95%CI:0.926-0.976, P = 0.000), high-density lipoprotein cholesterol (HDL-c) (OR = 0.217, 95%CI:0.074-0.637, P = 0.005), γ-glutamyltransferase (γ-GT) (OR = 1.016, 95%CI:1.004-1.027, P = 0.006), and creatinine (Cr) (OR = 1.042, 95%CI: 1.017-1.067, P = 0.001) were independent predictors of hyperuricemia. SUA levels significantly declined in all patients from 443.1 ± 118.2 μmol/L before surgery to 370.1 + 113.4 μmol/L at 12 months after surgery. The prevalence of hyperuricemia also declined from 69.4% before surgery to 25.5% at 12 months. Multiple linear regression analyses confirmed that changes in Cr and body mass index (BMI) were independent predictors of a decrease in SUA levels, 12 months postoperatively.

CONCLUSIONS

Hyperuricemia in Chinese bariatric surgery candidates are common, especially in males. Age, HDL-c, γ-GT and Cr were determined to be independent predictors of hyperuricemia. Bariatric surgery may effectively reduce the prevalence of hyperuricemia in this population, through postoperative weight loss and changes in creatinine following the procedure.

Association Between Sex-Specific Serum Gamma-Glutamyltransferase and Incidence of Hypertension in a Chinese Population Without Metabolic Syndrome: A Prospective Observational Study

Background: Higher serum gamma-glutamyltransferase (GGT) is associated with high risk of hypertension. We aimed to examine the association between sex-specific serum GGT levels and incident of hypertension in a Chinese population without metabolic syndrome. Methods: Participants who were free of hypertension and metabolic syndrome from the First Affiliated Hospital of Wenzhou Medical University between 2009 and 2014 were included. Participants were grouped into sex-specific quartiles of GGT levels (Q1-Q4) defined as: ≤19, 20-26, 27-38, and ≥39 U/L for male; ≤12, 13-15, 16-19, and ≥20 U/L for female. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for incidence of hypertension according to sex-specific quartiles of GGT levels. Kaplan-Meier analysis and interaction analysis were conducted. Results: Among 38,806 participants included (average age 36.0 years, 54.0% men), 4,505 of them developed hypertension. In the overall study population, using Q1 as the reference group, participants in Q2, Q3, and Q4 showed a higher risk of developing hypertension, with HRs (95% CIs) of 1.126 (1.029-1.232), 1.187 (1.083-1.302), and 1.300 (1.182-1.431), respectively (P < 0.001), after adjusting for known confounders. Sex-specific analysis showed that the adjusted HRs for participants in Q4 (reference: Q1) were greater in females [1.321 (1.100-1.586, P < 0.001)] than in males [1.268 (1.133-1.420, P < 0.001)] (P for interaction = 0.047). Moreover, interaction analysis showed that this association was consistently observed when the participants were stratified by age, body mass index, and fatty liver status. Conclusion: Among Chinese adults without metabolic syndrome, serum GGT level was positively associated with incidence of hypertension, and the association was stronger in females than in males.

Index of Cardiac Age Index and Cardiometabolic Biomarkers in Adults with Metabolic Syndrome

Background: The presence of metabolic syndrome (MetS) seems to alter or accelerate the aging process of tissues or organs including the heart. We aim to investigate whether MetS are associated with an index of cardiac age calculated by parameters derived from 128-slice cardiac multidetector computed tomography (MDCT) and cardiometabolic biomarkers in adults. Materials and Methods: In this cross-sectional study, the data were collected from 135 subjects who underwent a comprehensive health checkup, including cardiac MDCT in adults (age ≥18 years). Cardiometabolic biomarkers and an index of cardiac age were measured. Results: Sixty-one (45.2%) had MetS and 44 subjects (32.6%) presented with moderate or severe coronary artery stenosis (CAS) on cardiac MDCT. MetS had positive correlations with several anthropometric variables, metabolic variables [triglyceride, gamma-glutamyl transpeptidase (GGT), homeostatic model assessment of insulin resistance (HOMA-IR)], and systolic blood pressure, cardiac parameters, an index of cardiac age and CAS, whereas had a negative correlation with high-density lipoprotein cholesterol. The diagnostic accuracy for MetS had similar area under the curve among the four variables (index of cardiac age, CAS, HOMA-IR, GGT). On age-adjusted multivariate analysis, only high index of cardiac age (≥55.0 years), and high HOMA-IR (≥1.22) were significantly and independently associated with MetS [odds ratio (OR) 2.48, 95% confidence interval (CI) 1.19-5.18, P = 0.016 and OR 3.41, 95% CI 1.65-7.06, P = 0.001, respectively]. Conclusion: Adults with MetS had higher index of cardiac age and higher HOMA-IR, compared with adults without MetS.

Comparability of four clinical laboratory measurement methods for GGT and commutability of candidate reference materials

Background

This study was conducted to evaluate the progress in the standardization of the gamma‐glutamyl transferase (GGT) to achieve metrological traceability of routine in vitro diagnosis (IVD) medical devices.

Methods

We collected 25 single fresh frozen serum samples for GGT analysis. Candidate reference materials (RMs), calibrators, internal quality controls (IQC), and external quality assessment (EQA) materials from the National Center for Clinical Laboratory (NCCL), Beijing Center for Clinical Laboratory (BCCL), and College of American Pathologists (CAP) were randomly added to these serum samples. A total of 42 samples were examined using IFCC reference method and four different IVD medical devices to perform the comparability and commutability study.

Results

The four IVD medical devices achieved trueness assessment within the measurement range. Linear analysis showed the agreement of Siemens ADVIA 2400, Hitachi 7600‐020/BioSino, Beckman AU 5800, and Roche Cobas 501 with the reference method. These assay pairs were comparable at the medical decision levels. The GGT in‐house candidate RMs, and Beckmann and Roche calibrators were all within the limits of the 95% prediction intervals, the commutability of BioSino calibrators was indeterminate, and some internal and external quality controls were not commutable for comparisons of certain IVD medical devices vs the reference method.

Conclusions

By comparing with the reference method, we found that performance of GGT conventional measurement systems to be traceable to the higher order references was improved. The commutable materials for calibration and trueness controls of routine methods were significant to promote the standardization of GGT analysis.

Association of hyperuricemia and gamma glutamyl transferase as a marker of metabolic risk in alcohol use disorder

Excessive alcohol consumption leads to overproduction of urates and renal function plays a critical role in serum uric acid levels. We aimed to assess associations of hyperuricemia in patients with alcohol use disorder (AUD) and comparable Glomerular Filtration Rate (GFR). A total of 686 patients undergoing treatment for AUD between 2013 and 2017 were eligible (77% men); age at admission was 47 years [interquartile range (IQR), 40-53 years], age of onset of alcohol consumption was 16 years [IQR, 16-18 years] and the amount of alcohol consumed was 160 g/day [IQR, 120-240 g/day]. Body Mass Index was 24.7 kg/m² [IQR, 21.9-28.4 kg/m²], eGFR was 105 mL/min/1.73 m² [IQR, 95.7-113.0 mL], 9.7% had metabolic syndrome and 23% had advanced liver fibrosis (FIB-4 > 3.25). Prevalence of hyperuricemia was 12.5%. The eGFR-adjusted multivariate analysis showed that relative to patients with GGT ≤ 50, those with GGT between 51 and 300 U/L and those with GGT > 300 U/L were 4.31 (95% CI 1.62-11.46) and 10.3 (95% CI 3.50-29.90) times more likely to have hyperuricemia, respectively. Our data shows that hyperuricemia in the context of AUD is strongly associated with serum GGT levels and suggest an increased cardio-metabolic risk in this population.

Prognostic Value of Gamma-Glutamyltransferase in Male Patients With Idiopathic Pulmonary Arterial Hypertension

Background: The elevated gamma-glutamyltransferase (GGT) activity is regarded as an indicator of cardiovascular disease, with males having higher values than females. The greater incidence of idiopathic pulmonary arterial hypertension (IPAH) is observed in women, whereas prognosis is poor in men. The present study aims to investigate the potential association of GGT on male patients.

Methods: Serum GGT levels were measured in 338 consecutive adult IPAH patients, who underwent bone morphogenetic protein receptor type 2 (BMPR2) genetic counseling, and matched with healthy subjects by sex and age. The followed interval was 48 ± 34 months.

Results: Increased serum GGT levels were more common in patients with IPAH than controls (p < 0.001). GGT values were significantly higher in male patients than those of females (p < 0.001). Compared with female patients with BMPR2 mutation, GGT level in male patients with BMPR2 mutation was further increased (p = 0.002). Higher GGT levels were associated with worse hemodynamics and Nterminal pro B-type natriuretic peptide in all patients. However, males with a GGT concentration ≥ 53 U/L had a worse survival than those of females. Contrarily, if GGT concentration <53 U/L, there was no survival difference between male and female patients. After adjustment for relevant variables of clinical features and hemodynamics, baseline higher GGT levels remained increased risks of all-cause mortality in males rather than females. During rehospitalization follow-up, male patients still had significantly higher values of GGT than females.

Conclusions: Increased GGT levels were correlated with BMPR2 mutation, hemodynamic dysfunction, and poor outcomes in male patients with IPAH. Further studies are needed to explain the origin of abnormal GGT and its potential pathogenesis in men.

Frequently abnormal serum gamma-glutamyl transferase activity is associated with future development of fatty liver: a retrospective cohort study

BACKGROUND

Nonalcoholic fatty liver disease is characterized by excessive hepatic fat accumulation. Some individuals frequently present elevated gamma-glutamyl transferase (GGT) levels without fatty liver ultrasound images and other abnormal liver enzymes levels. However, whether these individuals are at an elevated risk for developing fatty liver is unclear. We compared fatty liver change rates and risk factors between individuals with frequently elevated GGT levels and those with normal levels.

METHODS

We designed a retrospective cohort study on the basis of complete medical checkup records. One group of individuals had presented normal serum GGT levels during the observation period (Normal-GGT group, n = 2713). Another group had had abnormal elevated serum GGT levels frequently (Abnormal-GGT group, n = 264). We determined the fatty liver change incident rates before and after propensity score matching. We explored confounding factors affecting fatty changes in each group using univariate and multivariate Cox models.

RESULTS

The change incidence rates were 5.80/1000 and 10.02/1000 person-years in the Normal-GGT and Abnormal-GGT groups, respectively. After propensity score matching, the incidence rates were 3.08/1000 and 10.18/1000 person-years in the Normal-GGT and Abnormal-GGT groups, respectively (p = 0.026). The factors associated with fatty liver changes in the Normal-GGT group included body mass index (BMI), hemoglobin, alanine aminotransferase (ALT), albumin, triglyceride (TG), fasting blood sugar, and high-density lipoprotein levels. Those in the Abnormal-GGT group were platelet counts and TG. In our multivariable analysis, BMI, ALT, albumin, and TG levels were independent predictors of fatty changes in the Normal-GGT group, and high TG level was the only independent predictor in the Abnormal-GGT group.

CONCLUSIONS

The incidence rate of fatty liver change in the Abnormal-GGT group was higher than that in the Normal-GGT group. Consecutive elevated GGT levels increase the risk for fatty liver, and high TG levels in those individuals further independently increase the risk.

Atrial fibrillation and gamma glutamyl transferase; Off-pump versus on-pump Coronary Artery Bypass surgery

Introduction: Atrial fibrillation (AF) which can be seen as a complication of the open-heart surgery, may cause serious problems on postoperative period. The exact pathophysiology of AF is unknown but it is thought that factors such as oxidative stress might cause AF. Material and methods: We retrospectively surveyed the serum gamma-glutamyl transferase (GGT) levels which is accepted as a mediator of oxidative stres, for the Post Operative Atrial Fibrillation (POAF) that occur after of-pump versus on-pump Coronary Artery Bypass Graft (CABG) surgery. Our study included 183 cases (101 male, 72 female; median age 63 ± 4.3 years) of which CABG was performed. Results: Echocardiography, routine blood tests, electrocardiography (ECG), test for the serum GGT levels were performed in preoperative and postoperative period to all participants. AF developed in 34 patients (35 %) in Group I and 19 patients (20 %) in Group II. There were no significant differences between two groups (of-pump versus on-pump) in terms of gender, cardiovascular risk factors and the severity of the coronary artery disease. In patients who has developed AF in postoperative period had significantly higher serum GGT levels. Conclusion: This study has shown that serum GGT levels were found to be significantly higher in patients whom AF has developed after on-pump CABG surgery.

Biomarkers and their relative contributions to identifying coronary artery stenosis based on coronary computed tomography angiography in asymptomatic adults

BACKGROUND

Coronary computed tomography angiography (CCTA) has emerged as an important, non-invasive imaging modality for the assessment of coronary vascular disease. However, CCTA as a screening tool still has issues with radiation exposure and cost in asymptomatic adults. In this study, we investigated the relationship between cardio-metabolic biomarkers and coronary artery stenosis on CCTA in asymptomatic, apparently healthy adults.

METHODS

Data for this cross-sectional study were obtained from 306 subjects who underwent a comprehensive medical check-up including CCTA. A 128-slice CT device was used to detect earlier stages of coronary stenosis, which was defined as > 25% luminal reduction in the most severe stenosis in the calcified segments of the coronary arteries.

RESULTS

On multivariate analysis, after adjustment for age, only γ-glutamyl transferase (GGT) was significantly and independently associated with CCTA stenosis (OR 1.006, 95% CI 1.001-1.011, P = .026). In a subgroup analysis of 103 subjects with brachial-ankle pulse wave velocity (baPWV) data, baPWV was significantly associated with CCTA stenosis (OR 1.005; 95% CI 1.003-1.008, P < .001).

CONCLUSIONS

GGT and baPWV were associated independently with the presence of CCTA stenosis in apparently healthy adults. Further research is needed to re-confirm on these findings.

A Review of Dietary (Phyto)Nutrients for Glutathione Support

Glutathione is a tripeptide that plays a pivotal role in critical physiological processes resulting in effects relevant to diverse disease pathophysiology such as maintenance of redox balance, reduction of oxidative stress, enhancement of metabolic detoxification, and regulation of immune system function. The diverse roles of glutathione in physiology are relevant to a considerable body of evidence suggesting that glutathione status may be an important biomarker and treatment target in various chronic, age-related diseases. Yet, proper personalized balance in the individual is key as well as a better understanding of antioxidants and redox balance. Optimizing glutathione levels has been proposed as a strategy for health promotion and disease prevention, although clear, causal relationships between glutathione status and disease risk or treatment remain to be clarified. Nonetheless, human clinical research suggests that nutritional interventions, including amino acids, vitamins, minerals, phytochemicals, and foods can have important effects on circulating glutathione which may translate to clinical benefit. Importantly, genetic variation is a modifier of glutathione status and influences response to nutritional factors that impact glutathione levels. This narrative review explores clinical evidence for nutritional strategies that could be used to improve glutathione status.

Ozone-induced changes in the serum metabolome: Role of the microbiome

Ozone is an asthma trigger. In mice, the gut microbiome contributes to ozone-induced airway hyperresponsiveness, a defining feature of asthma, but the mechanistic basis for the role of the gut microbiome has not been established. Gut bacteria can affect the function of distal organs by generating metabolites that enter the blood and circulate systemically. We hypothesized that global metabolomic profiling of serum collected from ozone exposed mice could be used to identify metabolites contributing to the role of the microbiome in ozone-induced airway hyperresponsiveness. Mice were treated for two weeks with a cocktail of antibiotics (ampicillin, neomycin, metronidazole, and vancomycin) in the drinking water or with control water and then exposed to air or ozone (2 ppm for 3 hours). Twenty four hours later, blood was harvested and serum analyzed via liquid-chromatography or gas-chromatography coupled to mass spectrometry. Antibiotic treatment significantly affected 228 of the 562 biochemicals identified, including reductions in the known bacterially-derived metabolites, equol, indole propionate, 3-indoxyl sulfate, and 3-(4-hydroxyphenyl)propionate, confirming the efficacy of the antibiotic treatment. Ozone exposure caused significant changes in 334 metabolites. Importantly, ozone-induced changes in many of these metabolites were different in control and antibiotic-treated mice. For example, most medium and long chain fatty acids declined by 20-50% with ozone exposure in antibiotic-treated but not control mice. Most taurine-conjugated bile acids increased with ozone exposure in antibiotic-treated but not control mice. Ozone also caused marked (9-fold and 5-fold) increases in the polyamines, spermine and spermidine, respectively, in control but not antibiotic-treated mice. Each of these metabolites has the capacity to alter airway responsiveness and may account for the role of the microbiome in pulmonary responses to ozone.

The value of gamma glutamyltransferase in predicting myocardial infarction in patients with acute coronary syndrome

Aim: To assess the utility of gamma-glutamyl transferase (GGT) and C-reactive protein (CRP) in predicting troponin elevation in patients with acute coronary syndrome. Patients: The total of 119 patients were divided into troponin-positive (n = 61) and troponin-negative (n = 58) patients. Results: CRP cut-off value ≥13.4 mg/l had the sensitivity of 68.1% and specificity of 62.5%, while the GGT cut-off value ≥61.5 IU/l had the sensitivity of 66.0% and specificity of 62.0% and combined use of both CRP and GGT had 71.4% sensitivity and 69.6% specificity in predicting troponin increase in acute coronary syndrome patients. Conclusion: GGT might be used as an adjuvant marker for risk assessment patients who present with chest pain and are suspected to have acute coronary syndrome.

Gamma-glutamyltransferase activity as a surrogate biomarker of metabolic health status in young nondiabetic obese women

Aim: We investigated the association of gamma-glutamyltransferase (GGT) activity with atherogenic risk factors and metabolic health status in young nondiabetic obese women. Methods & results: In 140 obese women GGT activity was independently associated with BMI, triglyceride to high-density cholesterol ratio and homeostasis model assessment. Metabolically healthy but obese women had significantly lower GGT activity, associated with a normal insulin sensitivity, favorable lipid profile and apolipoprotein B to apolipoprotein AI ratio. GGT activity showed good diagnostic accuracy to distinguish between metabolically healthy but obese and obese women at risk (77.8% sensitivity and 60% specificity). GGT activity >17 U/l can predict atherogenic risk and insulin resistance. Conclusion: GGT activity may serve as a potential surrogate biomarker of atherogenic risk and metabolic health status.

Acute mercury exposition of virgin, pregnant, and lactating rats: Histopathological kidney and liver evaluations

This work investigated the effects of mercury chloride (HgCl₂ ) acute exposure on virgin, pregnant and lactating rats by determination of renal and hepatic morphological and ultrastructural parameters and the expression of oxidative stress and stress tolerance markers, due to kidney and liver are the organs that more accumulate inorganic mercury. Adult Wistar rats virgin (90 days old), pregnant (18^th gestation day) and lactating (7^th lactation day) were injected once with HgCl₂ (5 mg/kg) or saline (controls). We observed that HgCl₂ exposure of virgin rats caused significant inflammatory infiltration and severe morphological variations, like glomeruli atrophy, dilatation of Bowman's capsule, tubular degeneration and hepatocytes alteration. Moreover, virgin rats presented mitochondrial modification, important oxidative stress and increase in stress tolerance proteins at both kidney and liver level, compared with virgin controls. In detail, virgin rats exposed to HgCl₂ presented significantly elevated level of inducible nitric oxide synthase, heat shock protein 27 and glucose regulated proteins 75 expressions at both renal tubular and hepatocytes level, respect untreated virgin rats. Interestingly, pregnant and lactating rats exposed to HgCl₂ presented weak renal and liver morphological alterations, showing weak inflammatory infiltration and no significant difference in structural mitochondrial transmembrane protein, oxidative stress markers and stress tolerance proteins expressions respect controls (virgin, pregnant and lactating rats). Although, both control and HgCl₂ -exposed pregnant and lactating rats showed renal glomeruli greater in diameter respect virgin rats. In conclusion, we believe that virgin rats are more sensitive to HgCl₂ toxicity respect pregnant and lactating rats. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1500-1512, 2017.

Gamma-glutamyltransferase and risk of cardiovascular mortality: A dose-response meta-analysis of prospective cohort studies

BACKGROUND

Serum gamma-glutamyltransferase (GGT) elevation likely contributes to cardiovascular (CV) mortality, however it has remained unknown whether a dose-response relationship exists between serum GGT and CV mortality.

METHODS

We searched the PubMed, EMBASE, and Cochrane library databases for prospective cohort studies published up to October 2, 2016. Summary hazard ratios (HRs) with their corresponding 95% confidence intervals (CIs) were calculated using a fixed effects model.

FINDINGS

Nine prospective studies, including 527,589 participants and more than 7,011 cases, were included in this meta-analysis. For the moderate, high, and highest levels of GGT, the pooled HRs of CV mortality were 1.11 (95% CI = 1.04-1.19), 1.29 (95% CI = 1.21-1.38) and 1.59 (95% CI = 1.47-1.72), respectively (all p < 0.05 as compared to the lowest levels of GGT). Additionally, the HR per incremental increase of GGT by 10 U/L was 1.10 (95% CI = 1.08-1.11). Evidence of a positive relationship with nonlinear trend for GGT elevation with CV mortality in females was found (P = 0.04 for nonlinearity). However, a linear model was better fit to illustrate the GGT-CV mortality among males (P = 0.304 for nonlinearity).

CONCLUSIONS

These findings indicate that serum GGT activity within the reference interval is positively associated with increased risk of CV mortality in a dose-response manner.

Gamma-glutamyl transferase and cardiovascular disease

Gamma-glutamyl transferase (GGT) is an enzyme located on the external surface of cellular membranes. GGT contributes in maintaining the physiological concentrations of cytoplasmic glutathione and cellular defense against oxidative stress via cleavage of extracellular glutathione and increased availability of amino acids for its intracellular synthesis. Increased GGT activity is a marker of antioxidant inadequacy and increased oxidative stress. Ample evidence suggests that elevated GGT activity is associated with increased risk of cardiovascular disease (CVD) such as coronary heart disease (CHD), stroke, arterial hypertension, heart failure, cardiac arrhythmias and all-cause and CVD-related mortality. The evidence is weaker for an association between elevated GGT activity and acute ischemic events and myocardial infarction. The risk for CVD or CVD-related mortality mediated by GGT may be explained by the close correlation of GGT with conventional CVD risk factors and various comorbidities, particularly non-alcoholic fatty liver disease, alcohol consumption, oxidative stress, metabolic syndrome, insulin resistance and systemic inflammation. The finding of GGT activity in atherosclerotic plaques and correlation of intra-plaque GGT activity with histological indexes of plaque instability may suggest a participation of GGT in the pathophysiology of CVD, particularly atherosclerosis. However, whether GGT has a direct role in the pathophysiology of CVD or it is an epiphenomenon of coexisting CVD risk factors or comorbidities remains unknown and Hill's criteria of causality relationship between GGT and CVD are not fulfilled. The exploration whether GGT provides prognostic information on top of the information provided by known cardiovascular risk factors regarding the CVD or CVD-related outcome and exploration of molecular mechanisms of GGT involvement in the pathophysiology of CVD and eventual use of interventions to reduce circulating GGT activity remain a duty of future studies.