Gamma-glutamyltransferase-associated glycoprotein patterns in human seminal plasma of normozoospermic men: a new aspect of biomarker heterogeneity

BACKGROUND

Gamma-glutamyltransferase (GGT) is a well-known laboratory biomarker. In spite of high concentration and the possible biomedical importance of estimating GGT in human seminal plasma (hSP), it has not been widely explored in reproductive physiology. This study aimed to complement existing data on its diversity, previously obtained on seminal extracellular vesicles, by analyzing matched soluble fraction of hSP. The GGT-associated patterns of selected glycoproteins were analyzed in order to establish an adjunct referent parameter for differentiation between known high molecular mass forms of GGT. Getting insight into distinct GGT-associated glycoprotein patterns should contribute to define them together as possible multimarkers.

METHODS

GGT forms in soluble, membrane-free-fraction isolated form hSP of normozoospermic men were analyzed using gel filtration and lectin blotting using WGA (wheat germ agglutinin) and Con A (concanavalin A).

RESULTS

Widely distributed GGT (with two to three partially resolved peaks), which may correspond to high molecular mass aggregates, were detected. GGT-associated patterns of selected glycoproteins (at position of big, medium, and small-GGT) all comprised high molecular mass WGA-reactive smears, but differed in the presence of Con A-reactive glycans, as well as mucin-associated antigens CA19-9 and CA125.

CONCLUSIONS

GGT contributes to several molecular patterns that differ between the soluble and extracellular vesicle fractions of hSP. Their glycobiochemical heterogeneity is due to difference in the presence of distinct sialylated and mannosylated glycans. Moreover, GGT-associated glycoprotein patterns differentiate between high molecular mass forms of GGT in the soluble fraction of hSP. They hold promise as possible targets for increasing biomarker potential of GGT.

Advances and Perspectives of Responsive Probes for Measuring γ-Glutamyl Transpeptidase

Gamma-glutamyltransferase (GGT) is a plasma-membrane-bound enzyme that is involved in the γ-glutamyl cycle, like metabolism of glutathione (GSH). This enzyme plays an important role in protecting cells from oxidative stress, thus being tested as a key biomarker for several medical conditions, such as liver injury, carcinogenesis, and tumor progression. For measuring GGT activity, a number of bioanalytical methods have emerged, such as chromatography, colorimetric, electrochemical, and luminescence analyses. Among these approaches, probes that can specifically respond to GGT are contributing significantly to measuring its activity in vitro and in vivo. This review thus aims to highlight the recent advances in the development of responsive probes for GGT measurement and their practical applications. Responsive probes for fluorescence analysis, including "off-on", near-infrared (NIR), two-photon, and ratiometric fluorescence response probes, are initially summarized, followed by discussing the advances in the development of other probes, such as bioluminescence, chemiluminescence, photoacoustic, Raman, magnetic resonance imaging (MRI), and positron emission tomography (PET). The practical applications of the responsive probes in cancer diagnosis and treatment monitoring and GGT inhibitor screening are then highlighted. Based on this information, the advantages, challenges, and prospects of responsive probe technology for GGT measurement are analyzed.

Gamma-Glutamyl Transferase as a Diagnostic Marker of Metabolic Syndrome

Introduction The metabolic syndrome consists of metabolic abnormalities that increase the risk of cardiovascular disease (CVD) and cerebrovascular disease. Metabolic syndrome (MetS) is a growing problem worldwide, and substantial efforts have been made in the last years to identify early, minimally invasive blood-based biomarkers for its diagnosis. This study attempted to assess how serum Gamma-Glutamyl Transferase (GGT) performed as an ideal endogenous substance for the diagnosis of metabolic syndrome and hence estimate cardiovascular risks. Methodology This study has been undertaken to assess the role of GGT as a marker in the diagnosis of metabolic syndrome and to assess the sensitivity and specificity of GGT in the diagnosis of metabolic syndrome. One hundred and eighty subjects were recruited comprising 90 cases of MetS and an equal number of age and gender-matched controls. Patients were recruited into the study group after satisfying the International Diabetes Federation (IDF) criteria for MetS. GGT values were obtained for both groups apart from other parameters. The patients in the study were also evaluated for the presence of cardiovascular diseases and cerebrovascular accidents (CVA). Results Sixty cases have GGT levels above the normal range (55 in males and 38 in females), and none in the control group have GGT levels above normal. This difference is statistically significant (p=0.01). The sensitivity was found to be 67% and 94% for males and females respectively. The specificity was found to be 100% and 98% for males and females respectively. Among the 90 cases, 20 (22.2%) patients developed cardiovascular disease. None in the control group developed cardiovascular disease. This difference is statistically significant (p<0.05). Conclusion Serum GGT appears to be an easily available and fairly good marker for diagnosing patients with metabolic syndrome and is independent of other parameters of metabolic syndrome. It is also a strong predictor of cardiovascular disease. Hence GGT can be considered a potential marker for the evaluation of patients with metabolic syndrome.

Serum γ-glutamyltransferase level and incidence risk of metabolic syndrome in community dwelling adults: longitudinal findings over 12 years

PURPOSE

Although a recent meta-analysis demonstrated a positive association between serum γ-glutamyltransferase (GGT) and metabolic syndrome (MetS), sex differences in the relationship between GGT levels and MetS risk were not fully considered. We prospectively examined the relationship between serum GGT levels and incidence risk of MetS.

METHODS

Data were collected from the Korean Genome and Epidemiology Study (KoGES) enrolled in 2001-2002. Among 10,030 total participants, 5960 adults (3130 men and 2830 women) aged 40-69 without MetS were included and divided according to sex-specific quartiles of baseline serum GGT levels and followed up biennially until 2014. The hazard ratios (HRs) with 95% confidence intervals (CIs) for incident MetS were prospectively analyzed using multiple Cox proportional hazards regression analysis models.

RESULTS

Among 5960 participants, 1215 males (38.8%) and 1263 females (44.6%) developed MetS during 12-year follow up. Higher quartiles of GGT showed significantly higher cumulative incidence of MetS in both sexes (log-rank test P < 0.001). The HRs (95% CIs) for incident type 2 diabetes for the highest quartile versus referent lowest quartile for serum GGT levels were 3.01 (2.35-3.76) for men and 1.83 (1.30-2.57) for women after adjusting for age, smoking status, daily alcohol intake (g/day), regular exercise, family history of diabetes, and log-transformed LDL-cholesterol, creatinine, and aminotransferase levels.

CONCLUSION

In conclusion, high levels of GGT were found to be associated with increased risk of Mets in both men and women and the positive associations were stronger in men than in women.

Analysis of the effect of glutamyltransferase on hyperlipidemia based on decision tree

Objectives

This study is designed to analyze the potential influencing factors of hyperlipidemia, and to explore the relationship between liver function indicators such as gamma-glutamyltransferase (GGT) and hyperlipidemia.

Methods

Data were derived from 7599 outpatients who visited the Department of Endocrinology of the First Hospital of Jilin University (2017-2019). A multinomial regression model is used to identify related factors of hyperlipidemia and the decision tree method is used to explore the general rules in hyperlipidemia patients and non-hyperlipidemia patients on these factors.

Results

The average of age, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure, aspartate aminotransferase, alanine aminotransferase (ALT), GGT and glycosylated hemoglobin (HbA1c) in the hyperlipidemia group are higher than those in the non-hyperlipidemia group. In multiple regression analysis, SBP, BMI, fasting plasma glucose, 2-h postprandial blood glucose, HbA1c, ALT, GGT are associated with triglyceride. For people with HbA1c less than 6.0%, controlling GGT within 30 IU/L reduces the prevalence of hypertriglyceridemia by 4%, and for people with metabolic syndrome with impaired glucose tolerance controlling GGT within 20 IU/L reduces the prevalence of hypertriglyceridemia by 11%.

Conclusions

Even when GGT is in the normal range, the prevalence of hypertriglyceridemia increases with its gradual increase. Controlling GGT in people with normoglycemia and impaired glucose tolerance can reduce the risk of hyperlipidemia.

First Evidence of Prenatal Exposure to Emerging Poly- and Perfluoroalkyl Substances Associated with E-Waste Dismantling: Chemical Structure-Based Placental Transfer and Health Risks

Limited information is available about prenatal exposure to per- and polyfluoroalkyl substances (PFAS) in electronic waste (e-waste) recycling sites. In this study, we determined 21 emerging PFAS and 13 legacy PFAS in 94 paired maternal and cord serum samples collected from an e-waste dismantling site in Southern China. We found 6:2 fluorotelomer sulfonate (6:2 FTSA), 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA), and perfluorooctanephosphonate (PFOPA) as the major emerging PFAS, regardless of matrices, at median concentrations of 2.40, 1.78, and 0.69 ng/mL, respectively, in maternal serum samples, and 2.30, 0.73, and 0.72 ng/mL, respectively, in cord serum samples. Our results provide evidence that e-waste dismantling activities contribute to human exposure to 6:2 FTSA, 6:2 Cl-PFESA, and PFOPA. The trans-placental transfer efficiencies of emerging PFAS (0.42-0.94) were higher than that of perfluorooctanesulfonic acid (0.37) and were structure-dependent. The substitution of fluorine with chlorine or hydrogen and/or hydrophilic functional groups may alter trans-placental transfer efficiencies. Multiple linear regression analysis indicated significant associations between maternal serum concentrations of emerging PFAS and maternal clinical parameters, especially liver function and erythrocyte-related biomarkers. This study provides new insights into prenatal exposure to multiple PFAS in e-waste dismantling areas and the prevalence of emerging PFAS in people living near the sites.

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.

The modulatory effect of taurine on benzo (a) pyrene-induced hepatorenal toxicity

Toxicities linked with Benzo (a) pyrene B[a]P exposure, particularly in liver and kidney have been reported in both animals and humans. Taurine (2-aminoethane sulfonic acid) is an intracellular β-amino acid reported to elicit hepatorenal protective functions. However, the modulatory effect of taurine on hepatorenal toxicity associated with exposure to B[a]P has not been reported. This study evaluated the effects of taurine on the hepatorenal toxicities induced in cohorts of rats exposed to B[a]P. Experimental rats were treated as follows: B[a]P (10 mg/kg); co-treated cohorts -B[a]P (10 mg/kg) plus taurine (100 or 200 mg/kg) for 4 successive weeks. Results show that co-dosing with taurine significantly (P < 0.05) improved B[a]P-induced distortion of oxidative stress markers (catalase, superoxide dismutase, glutathione S-transferase, glutathione peroxidase, total sulphydryl, reduced glutathione, lipid peroxidation and xanthine oxidase), renal function (urea and creatinine) and liver function marker enzymes (alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase and gamma glutamyl transferase). Moreover, taurine effectively mitigated increase in myeloperoxidase activity, levels of reactive oxygen and nitrogen species, nitric oxide and interleukin-1β in kidney and liver of rats treated with B[a]P. In conclusion, taurine modulates hepatorenal toxicity in B[a]P-exposed rats by suppressing hepatic and renal damage indices, oxidative injury and inflammatory stress.

Associations of gamma-glutamyl transferase with cardio-metabolic diseases in people living with HIV infection in South Africa

Background

Gamma-glutamyl transferase (GGT) has recently been reported as a biomarker for cardiovascular (CVD) risk in general populations. We investigated the associations of GGT with cardio-metabolic diseases and CVD risk in South Africans living with HIV.

Methods

In this cross-sectional study, HIV-infected adults were randomly recruited across 17 HIV clinics in the Western Cape Province. Homeostatic model assessment for insulin resistance (HOMA-IR), hypertension, diabetes, metabolic syndrome by Joint Interim Statement criteria (JIS-MS), a ≥5% and ≥10% predicted risk for a CVD event within 10 years by the Framingham risk score (10-years-CVD risk) were computed. Associations between GGT and cardio-metabolic trait were explored using linear and binomial logistic regressions adjusted for age, gender, lifestyle behaviours and HIV-related characteristics.

Results

Among 709 participants (561 women, mean age 38.6 years), log-GGT was positively associated with waist circumference (β=2.75; p<0.001), diastolic blood pressure (β=1.65; p=0.006), total cholesterol (β=0.21; p<0.001), low-density lipoprotein-cholesterol (β=0.16; p<0.001), high-density lipoprotein-cholesterol and log-triglycerides (both β=0.12; p<0.001), fasting plasma glucose (β=0.19; p=0.031), 2-hour-post-glucose-load plasma glucose (β=0.26; p=0.007), HOMA-IR (β=0.13; p=0.001), log-high-sensitivity C-reactive-protein (β=0.3; p<0.001) in linear regression analyses; with hypertension [OR=1.41 (95%CI, 1.13-1.75); p=0.001], JIS-MS [OR=1.33 (1.05-1.68); p=0.016], ≥5% 10-year-CVD risk [OR=1.55 (1.24-1.9400); p<0.001] and ≥10% 10-year-CVD risk [OR=1.56 (1.08-2.23); p=0.016] but not with diabetes [OR=1.24 (0.88-1.71), p=0.205] in logistic regression analyses.

Conclusions

In this study, GGT levels were associated with cardio-metabolic variables independent of HIV specific attributes. If confirmed in longitudinal studies, GGT evaluation maybe included in CVD risk monitoring strategies in people living with HIV.

Serum γ-glutamyltransferase as an independent predictor for incident type 2 diabetes in middle-aged and older adults: Findings from the KoGES over 12 years of follow-up

BACKGROUNDS AND AIMS

Limited evidence is available on whether serum γ-glutamyltransferase (GGT) has value as a predictor of type 2 diabetes in East Asian populations. We investigated the causal relationship between serum GGT level and incident type 2 diabetes in Korean adults.

METHODS AND RESULTS

A total of 7739 nondiabetic adults aged 40-69 years from the Korean Genome and Epidemiology Study were studied. We divided the population into four groups according to sex-specific quartiles by serum GGT levels. Hazard ratios (HRs) with 95% Confidence intervals (CIs) for incident type 2 diabetes were prospectively analyzed using multivariate Cox proportional hazards regression models. A total of 1432 (18.5%) participants developed type 2 diabetes over 12 years of follow-up. The higher the serum GGT group quartile, the higher the cumulative type 2 diabetes incidence over 12 years with significance in both sexes (log-rank test P < 0.001). HRs (95% CIs) for incident type 2 diabetes for the highest quartile versus referent lowest quartile for serum GGT levels were 2.55 (1.86-3.51) for men and 1.90 (1.40-2.58) for women after adjusting for confounding variables.

CONCLUSIONS

Higher serum GGT levels preceded and positively associated with incident type 2 diabetes among community-dwelling middle-aged and older Korean adults.

Serum γ-Glutamyltransferase Concentration Predicts Endothelial Dysfunction in Naïve Hypertensive Patients

Background: Serum gamma-glutamyltransferase (γ-GT) is recognized as a risk factor for cardiovascular diseases (CV). Traditional cardiovascular risk factors mediate endothelial dysfunction. Aim: to evaluate a possible correlation between serum γ-GT and endothelium-dependent vasodilation in naïve hypertensives. Methods: We enrolled 500 hypertensives. Endothelial function was studied by strain-gauge plethysmography. Receiver operating characteristic (ROC) analysis was used to assess the predictive value of γ-GT and to identify the optimal cut-off value of the same variable for endothelial dysfunction. Results: At univariate linear analysis peak percent increase in acetylcholine (ACh)-stimulated vasodilation was inversely related to γ-GT (r = −0.587), alanine aminotransferase (ALT) (r = −0.559), aspartate aminotransferase (AST) (r = −0.464), age (r = −0.171), body mass index (BMI) (r = −0.152), and fasting glucose (r = −101). In the stepwise multivariate regression model, endothelium-dependent vasodilation was significantly related to γ-GT (β = −0.362), ALT (β = −0.297), AST (β = −0.217), estimated glomerular filtration rate (e-GFR) (β = 0.199), gender (β = 0.166), and smoking (β = −0.061). The ROC analysis demonstrated that the accuracy of γ-GT for identifying patients with endothelial dysfunction was 82.1%; the optimal γ-GT cut-off value for discriminating patients with this alteration was 27 UI/L. Conclusions: Serum γ-GT values, within the normal range, are significantly associated with endothelial dysfunction in hypertensives, and may be considered a biomarker of early vascular damage.

Prevalence of elevated liver enzymes and its association with type 2 diabetes: A cross-sectional study in Bangladeshi adults

BACKGROUND

Type 2 diabetes (T2D) is a major public health concern affecting millions of people worldwide. The relationship between liver enzymes and T2D has been reported in limited studies; however, there is still a lack of evidence for the Bangladeshi population. This study aimed to evaluate the prevalence of elevated liver enzymes and examine its association with the prevalence of T2D in Bangladeshi adults.

METHODS

A total of 270 individuals (110 diabetic and 160 nondiabetic) were enrolled in the study. Alanine and aspartate aminotransferase (ALT, AST), alkaline phosphatase (ALP) and γ-glutamyltransferase (GGT) activities were measured in blood serum collected from them. T2D was defined as fasting blood glucose (FBG) ≥126 mg/dL or self-reported recent use of insulin or antidiabetic medications. Association between liver enzymes and T2D was evaluated by multinomial logistic regression analysis.

RESULTS

Overall, 61.2% of participants in T2D and 37.1% of participants in the nondiabetes group had at least one or more elevated liver enzymes. The mean concentrations of serum ALT, AST, ALP and GGT were significantly higher in the T2D group compared to the nondiabetes group. The prevalence of elevated liver enzymes was significantly higher in the diabetes group compared to the nondiabetes group (P < .01). In regression analysis, serum GGT activity showed an independent association with the prevalence of T2D.

CONCLUSIONS

A high prevalence of elevated liver enzymes was observed in subjects having diabetes. Increased serum GGT activity was independently associated with the prevalence of T2D among Bangladeshi adults. More studies of this nature should be carried out in developing countries to get proper insights into the involvement of liver enzymes in T2D.

Nonalcoholic fatty liver disease is associated with both subcutaneous and visceral adiposity: A cross-sectional study

Nonalcoholic fatty liver disease (NAFLD) is recognized as a hepatic manifestation of metabolic syndrome because of the association with visceral obesity. However, the association between NAFLD and subcutaneous fat accumulation remains unclear.The study population included 3197 participants in regular health checkups, who were both hepatitis B virus surface antigen and hepatitis C virus antibody-negative, and consumed <20 g of alcohol per day. They were divided according to 4 quantiles of subcutaneous fat area (SFA) and visceral fat area (VFA) on computed tomography. Fatty liver was diagnosed using ultrasonography (FL-US).The prevalence of FL-US increased across the SFA categories, even after adjusting for the VFA, in both men (P < .001) and women (P < .001). This significant association between FL-US and the SFA was already detected from the second SFA quantile. It is noteworthy that the mean body mass index (BMI) of the subjects in the second quantile was 23.7 kg/m in men and 22.6 kg/m in women. Independent positive associations were observed between alanine aminotransferase elevation, and both the SFA and VFA in men, while gamma glutamyl transpeptidase elevation was independently associated with the VFA, but not the SFA, in both men and women. Similarly, the components of metabolic syndrome were independently associated with the VFA, but were less strongly associated (or not associated at all) with the SFA.This cross-sectional study suggests that NAFLD is independently associated with both visceral and subcutaneous adiposity ab initio, which is a characteristic that distinguishes NAFLD from other components of metabolic syndrome.

The combination of fatty liver and increased gamma-glutamyl transpeptidase levels as a risk factor for atherosclerotic plaque development in apparently healthy people

Background/aim

To elucidate how the combination of fatty liver and increased serum gamma-glutamyl transpeptidase (GGT) levels influences atherosclerotic plaque development in apparently healthy people.

Materials and methods

The study population included people who had received an annual health checkup for more than 7 years and had no evidence of carotid plaque at baseline. We investigated the risk factors for carotid plaque occurrence using the Cox proportional hazards model.

Results

A total of 107 people (76 men and 31 women; median age, 49 years) were enrolled. At baseline, fatty liver and a serum GGT level ≥50 U/L were observed in 13 and 38 people, respectively. During a median follow-up period of 13.3 years, carotid plaques appeared in 34 people. Multivariate analysis revealed that the combination of fatty liver and a serum GGT level ≥50 U/L was the only significant risk factor for carotid plaque occurrence (age- and sex-adjusted hazard ratio: 5.55; 95% confidence interval 1.70–18.14; P = 0.005).

Conclusion

The combination of fatty liver and increased serum GGT levels raises the risk for atherosclerotic plaque development in apparently healthy people.

EVALUATION OF SERUM γ-GLUTAMYL TRANSFERASE AND ITS ASSOCIATION WITH HIGH SENSITIVITY C-REACTIVE PROTEIN AND INSULIN LEVELS IN THE PATIENTS WITH METABOLIC SYNDROME

Background. Metabolic syndrome (MS), a collection of cardiovascular risk factors, is a major worldwide public health problem. The gathered data prove that serum gamma-glutamyl transferase (γGT) activity is a true marker of atherosclerotic cardiovascular disease (CVD) and is of a prognostic importance as well as the high-sensitivity C-reactive protein (hs-CRP). Objectives. In the study, we sought to evaluate serum γGT activity, hs-CRP and insulin resistance in patients with MS. Methods. The study involved 50 persons with metabolic syndrome and 50 healthy age and sex matched controls. Fasting serum samples of all participants were investigated for γGT, hs-CRP, insulin, blood glucose, lipid profile and liver function tests. Anthropometric measurements and BMI were also calculated Results. In that case 50% showed significantly high γGT compared to the controls, 30% proved increased hs-CRP levels above >0.5 mmol/L, whereas 94% of the controls were within the reference range. 74% of cases revealed the presence of insulin resistance while 32% of the controls showed insulin resistance. High γGT levels were also observed in that case with deranged lipids levels and high BMI. Conclusions. The study suggests that the patients with MS have a higher serum γGT activity. This study also proves that hs-CRP and HOMA-IR, which are independent risk factors of CVD, are also associated with MS. The correlation between γGT and the components of MS are also found significant compared to hs-CRP. Thus, γGT can be considered as an inexpensive and authentic predictor of MS, which can be a manifestation of CVD in near future.

Predicting risk of type 2 diabetes mellitus in Korean adults aged 40-69 by integrating clinical and genetic factors

AIMS

The purpose of our investigation was to identify the genetic and clinical risk factors of type 2 diabetes mellitus (T2DM) and to predict the incidence of T2DM in Korean adults aged 40-69 at follow-up intervals of 5, 7, and 10years.

METHODS

Korean Genome and Epidemiology Study (KoGES) cohort data (n=10,030) were used to develop T2DM prediction models. Both clinical-only and integrated (clinical factors+genetic factors) models were derived using the Cox proportional hazards model. Internal validation was performed to evaluate the prediction capabilities of the clinical and integrated models.

RESULTS

The clinical model included 10 selected clinical risk factors. The selected SNPs for the integrated model were rs9311835 in PTPRG, rs10975266 in RIC1, rs11057302 in TMED2, rs17154562 in ADAM12, and rs8038172 in CGNL1. For the clinical model, validated c-indices with time points of 5, 7, and 10 years were 0.744, 0.732, and 0.732, respectively. Slightly higher validated c-indices were observed for the integrated model at 0.747, 0.736, and 0.738, respectively. The p-values of the survival net reclassification improvement (NRI) for the SNP point-based score were statistically significant.

CONCLUSIONS

Clinical and integrated models can be effectively used to predict the incidence of T2DM in Koreans.

Serum gamma-glutamyl transferase is a predictor of mortality in patients with acute myocardial infarction

Gamma-glutamyl transferase (GGT) is involved in the pathogenesis of atherosclerosis and has been associated with adverse cardiovascular outcomes in patients with ischemic heart disease. However, the association between GGT and long-term mortality has not been studied in patients with acute myocardial infarction (AMI).A total of 2239 AMI patients for whom serum GGT values were available and who underwent percutaneous coronary intervention (PCI) were enrolled in the COREA-AMI (CardiOvascular Risk and idEntificAtion of potential high-risk population in Korean patients with AMI) registry. Patients with acute liver injury were excluded. Patients were classified into 2 groups according to normal (n = 1983) or elevated (n = 256) levels of serum GGT. The primary clinical outcome was all-cause mortality. The secondary outcome was cardiac death and recurrent non-fatal myocardial infarction (MI).The median follow-up period was 3.7 years, and both groups had similar characteristics. Patients with elevated GGT had significantly higher all-cause mortality compared to patients with normal GGT (21.9% vs. 14.4%, P = .001). The multivariate Cox proportional hazards model showed that elevated serum GGT level was independently correlated with mortality (hazard ratio 2.12[1.44-3.11]; P < .001). Although elevated serum GGT was independently associated with long-term mortality after 30 days after PCI, there was no association within 30 days after PCI. Elevated GGT was also associated with death of cardiac causes with statistical significance. In the subgroup analysis, stronger associations were observed in the young and female patients and in patients who had ST-segment elevation MI and preserved left ventricular ejection fraction at the first echocardiography after the indexed PCI.Elevated serum GGT is an independent predictor of long-term mortality in AMI patients.

Relationship between serum gamma-glutamyltransferase activity and cardiometabolic risk factors in metabolic syndrome

Objectives

The objective of this study was to examine the associations of serum gamma-glutamyltransferase (GGT) levels with the metabolic syndrome (MetS) and its components in Saudi adults.

Methods

The study comprised 400 participants (70 men and 330 women), aged between 40 and 88 years, randomly selected from the medicine clinics at the King Abdulaziz University Hospital in Jeddah, Saudi Arabia, in a cross-sectional study design. A standardized questionnaire was used to determine demographics variables, general health, lifestyle habits, and medical history. Anthropometric and biochemical variables measurements were taken for all study participants. MetS was defined according to the American Heart Association/National Heart, Lung, and Blood Institute report, by the presence of abdominal obesity.

Results

Higher means for triglycerides and insulin resistance indices (P < 0.0001) was found among those in the second, third, and fourth GGT quartiles as compared with their counterparts in the first quartile. McAuley index (β = -0.239, P < 0.0001, 95% confidence interval: -4.1--1.5) was shown to be a major determinant of circulating GGT in a multivariate analysis.

Conclusion

Elevated serum GGT could be a cardiometabolic risk factor either as a mediator of low-grade systemic inflammation and as a mediator of oxidative stress through mediation of extracellular glutathione transport into cells of organ systems.

Synthesis and evaluation of the inhibitory activity of the four stereoisomers of the potent and selective human γ-glutamyl transpeptidase inhibitor GGsTop

2-Amino-4-{[3-(carboxymethyl)phenoxy](methoxy)phosphoryl}butanoic acid (GGsTop) is a potent, highly selective, nontoxic, and irreversible inhibitor of γ-glutamyl transpeptidase (GGT). GGsTop has been widely used in academic and medicinal research, and also as an active ingredient (Nahlsgen) in commercial anti-aging cosmetics. GGsTop consists of four stereoisomers due to the presence of two stereogenic centers, i.e., the α-carbon atom of the glutamate mimic (l/d) and the phosphorus atom (R_P/S_P). In this study, each stereoisomer of GGsTop was synthesized stereoselectively and their inhibitory activity against human GGT was evaluated. The l- and d-configurations of each stereoisomer were determined by a combination of a chiral pool synthesis and chiral HPLC analysis. The synthesis of the four stereoisomers of GGsTop used chiral synthetic precursors that were separated by chiral HPLC on a preparative scale. With respect to the configuration of the α-carbon atom of the glutamate mimic, the l-isomer (k_on=174M^-1s^-1) was ca. 8-fold more potent than the d-isomer (k_on=21.5M^-1s^-1). In contrast, the configuration of the phosphorus atom is critical for GGT inhibitory activity. Based on a molecular modeling approach, the absolute configuration of the phosphorus atom of the active GGsTop isomers was postulated to be S_P. The S_P-isomers inhibited human GGT (k_on=21.5-174M^-1s^-1), while the R_P-isomers were inactive even at concentrations of 0.1mM.

Gallic Acid and Dodecyl Gallate Prevents Carbon Tetrachloride-Induced Acute and Chronic Hepatotoxicity by Enhancing Hepatic Antioxidant Status and Increasing p53 Expression

Gallic acid (3,4,5-trihydroxybenzoic acid, GA), a natural phenolic acid has been reported as a strong antioxidant. Therefore the present study was designed to evaluate the effects of GA and dodecyl gallate (DGA) against acute and chronic carbon tetrachloride (CCl₄)-induced hepatotoxicity. For acute model, rats were orally treated with GA and DGA for 7 d prior to CCl₄ by intraperitoneally (i.p.) injection. For the chronic model, rats were orally treated with GA or DGA and CCl₄ i.p. twice a week for four weeks. In both acute and chronic models, the CCl₄-treated groups showed significantly increase in serum hepatic enzyme activities and histopathologic alterations, as well as a disruption in antioxidative status. In contrast, the treatment with GA and DGA restored serum hepatic enzymes activities, improved histopathologic alterations, increased glutathione (GSH) and decreased lipid peroxidation levels. The activities of liver antioxidant enzymes were increased by GA and DGA only in acute model. The expression of p53 gene increased about 3.5 times after GA and DGA treatments, which could result in cell death of damaged hepatocytes preventing of a lifelong liver failure. Thus, these results suggest that GA and DGA has the potential to prevent liver damages as the case of fibrosis condition.

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.

The longitudinal effect of the aldehyde dehydrogenase 2*2 allele on the risk for nonalcoholic fatty liver disease

Aldehyde dehydrogenase 2 (ALDH2) detoxifies toxic aldehydes and has a key role in protecting the liver. An elevated gamma-glutamyl transferase (GGT) level is related to oxidative stress and nonalcoholic fatty liver disease (NAFLD). We herein investigated the association between inactive ALDH2*2 allele (rs671) and the risk of NAFLD, including the relationship to the GGT level. A retrospective follow-up study (mean 5.4±1.1 years) was conducted among 341 Japanese health screening program participants. The receiver operating characteristic curve indicated that the GGT level predicted the development of NAFLD (area under the curve: 0.65, P<0.05) with a cutoff value of 25.5 IUl⁻¹. The longitudinal risk of NAFLD was higher in the ALDH2*2 allele carriers than in the noncarriers (odds ratio (OR): 2.30, 95% confidence interval (CI): 1.21–4.40), and the risk was further increased among the *2 allele carriers with GGT values ⩾25.5 IUl⁻¹ (OR: 4.28, 95% CI: 1.80–10.19). On the other hand, there were no significant changes in the subjects' body weight and body mass index during observation period. The ALDH2*2 allele, in relation to the GGT level, may potentially be a novel risk factor for NAFLD.

Serum Gamma-glutamyl Transferase Concentration Within the Reference Range is Related to the Coronary Heart Disease Risk Prediction in Korean Men: Analysis of the Korea National Health and Nutrition Examination Survey (V-1, 2010 and V-2, 2011)

BACKGROUND

Limited data exist on the association of serum gamma-glutamyl transferase (GGT) level within the reference range with the increased risk of coronary heart disease (CHD) prediction in men. The study examined the association between serum GGT concentration within the reference range and the CHD risk prediction in Korean men.

METHODS

The study employed data from Korean National Health and Nutrition Examination Survey (V-1, 2010 and V-2, 2011) where a total of 1301 individuals were analyzed. A 10-year CHD risk prediction was computed using the Framingham Risk Score (FRS) modified by the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III).

RESULTS

Positive correlations were established between log-transformed GGT concentration and FRS (r = 0.237, P < 0.001). After adjustment of body mass index, the amount of alcohol intake and low-density lipoprotein-cholesterol, the odds ratio (95% confidence interval) for intermediate risk and beyond of 10-year CHD prediction (10-year risk ≥10%) with lowest quartile of participants was 1.21 (0.78-1.87) for second quartiles, 1.39 (0.88-2.21) for third quartiles and 2.03 (1.23-3.34) for highest quartiles.

CONCLUSIONS

Higher serum GGT within its reference range was significantly correlated with a 10-year CHD risk prediction estimation using NCEP ATP III in Korean men.

Association between liver enzymes and incident type 2 diabetes in Singapore Chinese men and women

AIMS

To assess the association between liver enzymes and the risk of type 2 diabetes (T2D) in a Chinese population.

METHODS

A nested case-control study comprising 571 T2D cases and 571 matched controls was conducted within the Singapore Chinese Health Study. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) were quantified in baseline plasma collected from them, while γ-glutamyltransferase (GGT) was assayed among 255 T2D cases with baseline hemoglobin A1c <6.5% and 255 matched controls. Participants were free of diagnosed diabetes, cardiovascular disease, and cancer at blood collections (1999-2004). Incident self-reported T2D cases were identified at follow-up II interview (2006-2010). Controls were matched to cases on age, sex, dialect group, and date of blood collection.

RESULTS

Higher levels of ALT and GGT were significantly associated with increased risk of T2D (p for trend <0.001 for ALT, p for trend=0.03 for GGT), and the ORs (95% CIs) comparing highest versus lowest tertiles of ALT and GGT were 2.00 (1.01 to 3.96) and 2.38 (1.21 to 4.66), respectively. A null association was observed for AST, ALP, and LDH with T2D risk. Adding GGT (<23 vs ≥23 IU/L) or ALT (<21 vs ≥21 IU/L) to a prediction model resulted in significant gain in net reclassification improvement and integrated discrimination improvement of T2D prediction (all p<0.001).

CONCLUSIONS

Higher levels of GGT and ALT are associated with increased T2D risk. GGT ≥23 IU/L and ALT ≥21 IU/L may identify people at higher risk of developing T2D in this Chinese population.

Free Radical-Scavenging, Anti-Inflammatory/Anti-Fibrotic and Hepatoprotective Actions of Taurine and Silymarin against CCl4 Induced Rat Liver Damage

The present study aims to investigate the hepatoprotective effect of taurine (TAU) alone or in combination with silymarin (SIL) on CCl₄-induced liver damage. Twenty five male rats were randomized into 5 groups: normal control (vehicle treated), toxin control (CCl₄ treated), CCl₄+TAU, CCl₄+SIL and CCl₄+TAU+SIL. CCl₄ provoked significant increases in the levels of hepatic TBARS, NO and NOS compared to control group, but the levels of endogenous antioxidants such as SOD, GPx, GR, GST and GSH were significantly decreased. Serum pro-inflammatory and fibrogenic cytokines including TNF-α, TGF-β1, IL-6, leptin and resistin were increased while the anti-inflammatory (adiponectin) cytokine was decreased in all treated rats. Our results also showed that CCl₄ induced an increase in liver injury parameters like serum ALT, AST, ALP, GGT and bilirubin. In addition, a significant increase in liver tissue hydroxyproline (a major component of collagen) was detected in rats exposed to CCl₄. Moreover, the concentrations of serum TG, TC, HDL-C, LDL-C, VLDL-C and FFA were significantly increased by CCl₄. Both TAU and SIL (i.e., antioxidants) post-treatments were effectively able to relieve most of the above mentioned imbalances. However, the combination therapy was more effective than single applications in reducing TBARS levels, NO production, hydroxyproline content in fibrotic liver and the activity of serum GGT. Combined treatment (but not TAU- or SIL-alone) was also able to effectively prevent CCl₄-induced decrease in adiponectin serum levels. Of note, the combined post-treatment with TAU+SIL (but not monotherapy) normalized serum FFA in CCl₄-treated rats. The biochemical results were confirmed by histological and ultrastructural changes as compared to CCl₄-poisoned rats. Therefore, on the basis of our work, TAU may be used in combination with SIL as an additional adjunct therapy to cure liver diseases such as fibrosis, cirrhosis and viral hepatitis.

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

γ-glutamyltransferase plays a key role in the synthesis and metabolism of extracellular glutathione, a major antioxidant in several defence mechanisms in the body. γ-glutamyltransferase is affected by environmental and genetic factors, and is raised when there is depletion of glutathione. Hence, it is a marker of oxidative stress. There is robust evidence that γ-glutamyltransferase even when values are within the reference interval is associated with increased cardiovascular and all-cause mortality in both sexes, in normal subjects and subjects with coronary artery disease, in the middle-aged and the elderly after adjusting for confounding factors. γ-glutamyltransferase even within the reference interval is associated with future presentation of type 2 diabetes, and the longitudinal increase in γ-glutamyltransferase activity is associated with increased risk of type 2 diabetes and cardiovascular mortality. γ-glutamyltransferase is associated with cardiovascular risk factors and metabolic syndrome. It has a prognostic value after a previous acute myocardial infarction and may be an indicator of adverse outcome in acute coronary syndromes and other chronic cardiac disorders. There is limited data about γ-glutamyltransferase and any association with peripheral arterial disease and also whether knowing γ-glutamyltransferase activity improves cardiovascular risk prediction beyond conventional risk factors. γ-glutamyltransferase is present in atherosclerotic lesions in the coronary and carotid arteries, and has a prooxidant role leading to the production of reactive oxygen species and atherosclerosis. Current reference intervals for γ-glutamyltransferase are inappropriate and need to be addressed. Some laboratories still use non- International Federation of Clinical Chemistry methods for estimation of γ-glutamyltransferase which are associated with lower results. Such laboratories should review their method and consider changing to the International Federation of Clinical Chemistry method.

Interactive effects of a common γ-glutamyltransferase 1 variant and low high-density lipoprotein-cholesterol on diabetic macro- and micro-angiopathy

BACKGROUND

We investigated the clinical relevance of a common variant, rs4820599, in the γ-glutamyltransferase (GGT)1 gene, associated with the serum GGT level, in Japanese type 2 diabetes mellitus (T2DM) subjects.

METHODS

We conducted a retrospective longitudinal study (4.9 ± 2.5 years) including 352 T2DM patients (T2DM subjects) and a cross-sectional study including 796 health screening program participants (general subjects). A real-time TaqMan allelic discrimination assay was used to identify the genotypes. Risk factors for a high brachial-ankle pulse wave velocity (baPWV) (≥1750 cm/sec) or diabetic retinopathy (DR) were determined using a generalized estimating equations approach, receiver operating characteristic (ROC) analysis or Cox proportional hazards model, etc.

RESULTS

The frequency of the GGT1 G allele was 20.8% in the T2DM subjects, and no associations were found between the GGT1 genotype and risk of T2DM. The mean log GGT values in the T2DM and general subjects were significantly higher among G allele carriers than non-carriers. The G allele and a low HDL-C level were identified to be risk factors for a high baPWV in the T2DM subjects [odds ratio (OR) 1.80, P = 0.008; OR 1.71, P = 0.03; respectively), and a significant interactive effect between these factors was found on the risk of a high baPWV and DR. The HDL-C level at baseline was a significant predictor of a high baPWV only in G allele carriers according to the ROC analysis. This result regarding baPWV in the T2DM subjects was replicated in the general population. Meanwhile, the GGT1 genotype was not associated with the risk of DR, although it affected the principal factors involved in the risk of DR, and a low HDL-C level was also found to be a risk factor for DR only in G allele carriers.

CONCLUSIONS

We herein describe for the first time the significant interactive effects of the GGT1 G allele and a low HDL-C level on a high baPWV and DR. These findings may encourage future clinical trials comparing the efficacy of agents increasing the HDL-C levels among the GGT1 genotypes. However, well-designed studies in larger cohorts are needed to confirm our results.

Presence of fatty liver and the relationship between alcohol consumption and markers of inflammation

Background and Aims. Local and systemic inflammation represent a major feature of atherosclerotic cardiovascular disease (CVD) and are also linked to nonalcoholic fatty liver disease (NAFLD). Studies indicate that NAFLD might be a risk factor for CVD whereas low-to-moderate alcohol consumption is associated with lower cardiovascular morbidity and mortality compared to abstainers and heavy drinkers. We hypothesize that FLD interacts with the effect of alcohol intake on markers of inflammation, and thus potentially on cardiovascular risk. Methods and Results. We evaluated alcohol consumption, markers of inflammation and sonographic criteria of FLD in 515 subjects, representing a subsample of a cross-sectional population based study (Echinococcus multilocularis and Internal Diseases in Leutkirch (EMIL) Study). Presence of FLD was markedly reduced in subjects drinking 0–20 g alcohol/d (19%), compared to nondrinkers (35%) and heavy drinkers (34–44.9%). Serum concentrations of inflammatory markers were substantially higher in subjects with FLD. However, presence of FLD showed no effect on the association between alcohol consumption and inflammatory biomarkers. Conclusions. Based on data from a population-based sample, there is no evidence for a link between FLD, alcohol consumption, and inflammatory cardiovascular risk markers. However, larger prospective studies are needed to confirm this.

Liver function parameters in hip fracture patients: relations to age, adipokines, comorbidities and outcomes

AIM

To asses liver markers in older patients with hip fracture (HF) in relation to age, comorbidities, metabolic characteristics and short-term outcomes.

METHODS

In 294 patients with HF (mean age 82.0±7.9 years, 72.1% women) serum alanine aminotransferase (ALT), gammaglutamyltransferase (GGT), alkaline phosphatase (ALP), albumin, bilirubin, 25(OH)vitaminD, PTH, calcium, phosphate, magnesium, adiponectin, leptin, resistin, thyroid function and cardiac troponin I were measured.

RESULTS

Elevated ALT, GGT, ALP or bilirubin levels on admission were observed in 1.7%-9.9% of patients. With age GGT, ALT and leptin decrease, while PTH and adiponectin concentrations increase. Higher GGT (>30 U/L, median level) was associated with coronary artery disease (CAD), diabetes mellitus (DM), and alcohol overuse; lower ALT (≤20 U/L, median level) with dementia; total bilirubin>20 μmol/L with CAD and alcohol overuse; and albumin>33 g/L with CAD. Multivariate adjusted regression analyses revealed ALT, ALP, adiponectin, alcohol overuse and DM as independent and significant determinants of GGT (as continuous or categorical variable); GGT for each other liver marker; and PTH for adiponectin. The risk of prolonged hospital stay (>20 days) was about two times higher in patients with GGT>30 U/L or adiponectin>17.14 ng/L (median level) and 4.7 times higher if both conditions coexisted. The risk of in-hospital death was 3 times higher if albumin was <33 g/L.

CONCLUSIONS

In older HF patients liver markers even within the normal range are associated with age-related disorders and outcomes. Adiponectin (but not 25(OH)vitaminD, PTH, leptin or resistin) is an independent contributor to higher GGT. Serum GGT and albumin predict prolonged hospital stay and in-hospital death, respectively. A unifying hypothesis of the findings presented.

Association of Serum Gamma-Glutamyl Transferase and Ferritin with the Metabolic Syndrome

Aim. To investigate the relationship among GGT, ferritin, and the risk of metabolic syndrome. Methods. A total of 1024 eligible individuals of the Chinese Yi ethnic group were enrolled in this cross-sectional study. The presence of metabolic syndrome was determined using the revised NCEP-ATP III and CDS criteria. Odds ratios for the metabolic syndrome and its components for different groups based on the levels of GGT and ferritin were calculated using multiple logistic regressions. Results. Serum GGT and ferritin concentrations were significantly higher in subjects with metabolic syndrome compared to those without metabolic syndrome in both genders (p < 0.05). Serum GGT was positively correlated with ferritin (p < 0.05). The risk of the metabolic syndrome was significantly higher in female subjects who had elevated GGT and ferritin levels (p < 0.05). Furthermore, the increased risk of having each of the metabolic syndrome components (overweight or obesity, hypertriglyceridemia, hypertension, hyperglycemia, and insulin resistance) was also observed in those subjects after adjustment for possible confounders (p < 0.05). Conclusions. These data indicate that GGT and ferritin synergistically correlate with the risk of the metabolic syndrome, suggesting that they could potentially be used as predictive biomarkers for the metabolic syndrome.

Detection of distinct glycosylation patterns on human γ-glutamyl transpeptidase 1 using antibody-lectin sandwich array (ALSA) technology

Background

γ-Glutamyl transpeptidase 1 (GGT1) is an N-glycosylated membrane protein that catabolizes extracellular glutathione and other γ-glutamyl-containing substrates. In a variety of disease states, including tumor formation, the enzyme is shed from the surface of the cell and can be detected in serum. The structures of the N-glycans on human GGT1 (hGGT1) have been shown to be tissue-specific. Tumor-specific changes in the glycans have also been observed, suggesting that the N-glycans on hGGT1 would be an important biomarker for detecting tumors and monitoring their progression during treatment. However, the large quantities of purified protein required to fully characterize the carbohydrate content poses a significant challenge for biomarker development. Herein, we investigated a new antibody-lectin sandwich array (ALSA) platform to determine whether this microanalytical technique could be applied to the characterization of N-glycan content of hGGT1 in complex biological samples.

Results

Our data show that hGGT1 can be isolated from detergent extracted membrane proteins by binding to the ALSA platform. Probing hGGT1 with lectins enables characterization of the N-glycans. We probed hGGT1 from normal human liver tissue, normal human kidney tissue, and hGGT1 expressed in the yeast Pichia pastoris. The lectin binding patterns obtained with the ALSA platform are consistent with the hGGT1 N-glycan composition obtained from previous large-scale hGGT1 N-glycan characterizations from these sources. We also validate the implementation of the Microcystis aeruginosa lectin, microvirin, in this platform and provide refined evidence for its efficacy in specifically recognizing high-mannose-type N-glycans, a class of carbohydrate modification that is distinctive of hGGT1 expressed by many tumors.

Conclusion

Using this microanalytical approach, we provide proof-of-concept for the implementation of ALSA in conducting high-throughput studies aimed at investigating disease-related changes in the glycosylation patterns on hGGT1 with the goal of enhancing clinical diagnoses and targeted treatment regimens.

Electronic supplementary material

The online version of this article (doi:10.1186/s12896-014-0101-0) contains supplementary material, which is available to authorized users.

The relationship between gamma-glutamyl transferase levels and coronary plaque burdens and plaque structures in young adults with coronary atherosclerosis

BACKGROUND

Elevated gamma-glutamyl transferase (GGT) levels have been demonstrated to be associated with poor prognoses in patients with coronary artery disease. Coronary computed tomography angiography (CCTA) is a noninvasive imaging modality that may differentiate the structure of coronary plaques. Elevated plaque burdens and noncalcified plaques, detected by CCTA, are important predictors of atherosclerosis in young adults.

HYPOTHESIS

The present study investigated the possible relationship between GGT levels and coronary plaque burdens/structures in young adults with coronary atherosclerosis.

METHODS

CCTA images of 259 subjects were retrospectively examined, and GGT levels were compared between patients with coronary plaques and individuals with normal coronary arteries. Coronary plaques, detected by CCTA, were categorized as noncalcified, calcified, and mixed, according to their structures. The significant independent predictors of coronary atherosclerosis were also analyzed using multivariate logistic regression analysis.

RESULTS

GGT levels were significantly higher in patients with coronary plaque formation than in controls (35.7 ± 14.7 vs 19.6 ± 10.0 U/L; P < 0.001). GGT levels were also positively correlated with the number of plaques; presence of noncalcified plaques; and levels of high-sensitivity C-reactive protein (hs-CRP), hemoglobin A1c, uric acid, and triglycerides. Moreover, smoking and levels of GGT, hs-CRP, uric acid, and low high-density lipoprotein cholesterol were independent predictors of coronary atherosclerosis.

CONCLUSIONS

GGT is an inexpensive and readily available marker that provides additional risk stratification beyond that provided by conventional risk factors for predicting coronary plaque burdens and plaque structures in young adults.

Increased levels of serum γ-glutamyltransferase and uric acid on metabolic, hepatic and kidney parameters in subjects at high altitudes

BACKGROUND

Currently there are no studies on γ-glutamyltransferase (γGT) levels at high altitude or on the relationship between γGT, uric acid and several dysfunctions. The aim of the study was to determine the association between serum γGT and uric acid levels in subjects at high altitude with hemoglobin, glycemia, and lipidic, hepatic and kidney markers.

METHODS

The present study was performed in 487 subjects aged 30-75 years living at 4100 m of altitude. A venous blood sample was drawn from each subject to measure hemoglobin, glucose, and lipid levels and markers of liver and kidney function. Quartiles for serum γGT and uric acid were calculated and associated with different physiological variables. A p-value <0.05 was considered statistically significant.

RESULTS

Serum γGT values were higher in men (38.35± 2.54 IU/L) than in women (30.33±1.76 IU/L) (p<0.01). Similarly, serum uric acid levels were higher in men (5.78± 0.12 mg/dL) than in women (4.29±0.08 mg/dL; p<0.001). Serum γGT levels in the top quartile were associated with higher glycemia, overweight/obesity, increased levels of non-high-density lipoprotein (non-HDL) cholesterol, triglycerides, alanine aminotransferase, alkaline phosphatase, uric acid, creatinine, and hemoglobin. Levels of uric acid in the top quartile were associated with overweight/obesity, elevated non-HDL cholesterol, triglycerides, creatinine, γGT and hemoglobin. Higher arterial blood pressure was associated with high levels of uric acid but not with γGT levels.

CONCLUSIONS

At high altitude, increased γGT levels were associated with hyperglycemia; increased uric acid levels were associated with overweight/obesity, hemoglobin, dyslipidemia, high blood pressure and kidney disease.

An association between serum γ-glutamyltransferase and proteinuria in drinkers and non-drinkers: a Japanese nationwide cross-sectional survey

BACKGROUND

The association between alcohol consumption and chronic kidney disease (CKD), characterized by reduced glomerular filtration rate and proteinuria, is controversial. Recent studies suggest that serum γ-glutamyltransferase (GGT) level, a conventional marker of excessive alcohol consumption, predicts the CKD incidence. Little information is available on the difference in the clinical impact of alcohol consumption and GGT on proteinuria.

METHODS

The present cross-sectional survey included 332,296 Japanese people aged ≥40 years in 2008. To examine the associations of GGT and alcohol consumption with proteinuria, 134,600 men and 197,696 women were classified into 20 categories based on GGT quartiles and alcohol consumption categories, and their prevalence rate ratios (PRR) of proteinuria defined as ≥1+ of dipstick urinary protein were calculated after adjusting for clinically relevant factors.

RESULTS

Prevalence of proteinuria was 7.5 and 3.7 % in men and women, respectively. In both gender an association between alcohol consumption and proteinuria was in a J-shaped fashion with the lowest PRR of mild drinkers with ≤19 g/day of ethanol consumption, whereas an association between serum GGT level and proteinuria was linear. Compared with rare drinkers in the lowest GGT quartile, the subjects in higher GGT quartiles had a higher probability of proteinuria, irrespective of alcohol consumption. An optimal cutoff level of serum GGT was 43.6 and 23.2 IU/L in men and women, respectively.

CONCLUSIONS

The subjects with higher serum GGT level had a higher probability of proteinuria, regardless of alcohol consumption, suggesting that GGT has a clinically greater impact on CKD than alcohol consumption.

Serum gamma glutamyl transferase and alanine transaminase concentrations predict endothelial dysfunction in patients with non-alcoholic steatohepatitis

PURPOSE

Cardiovascular diseases are the leading cause of death in patients with non-alcoholic steatohepatitis (NASH). We aimed to investigate the presence of endothelial dysfunction and whether serum concentrations of liver enzymes may reflect the severity of such an endothelial dysfunction in patients with NASH.

METHODS

Fifty patients with NASH diagnosed by liver biopsies and 30 healthy controls were included. Blood samples after fasting were harvested for measurements of glucose, insulin, cholesterol, triglyceride, and liver enzymes. All patients underwent transthoracic echocardiography and brachial and carotid artery Doppler ultrasonography to evaluate flow-mediated dilatation (FMD) and carotid artery intima-media thickness (CIMT).

RESULTS

Patients with NASH had impaired FMD (4.9 ± 2.8% to 9.3 ± 4.4%, P < 0.001) and higher CIMT (0.79 ± 0.16 mm to 0.64 ± 0.11 mm, P < 0.001) when compared with healthy controls. Linear regression analyses revealed that serum concentrations of gamma glutamyl transferase (GGT) and alanine transaminase (ALT) were associated with FMD and CIMT.

CONCLUSIONS

Patients with NASH have impaired FMD and increased CIMT when compared with healthy controls. In patients with NASH, serum concentrations of GGT and ALT might have a predictive value for FMD and CIMT.

Impact of gluten-free diet on cardiovascular risk factors. A retrospective analysis in a large cohort of coeliac patients

BACKGROUND

Concerns have been raised on whether a gluten-free diet affects the cardiovascular risk profile of coeliac patients.

AIMS

To assess changes of multiple cardiovascular risk factors in coeliac patients evaluated before and during a gluten-free diet.

METHODS

Retrospective analysis of the effects of 1-5 years of gluten-free diet on indicators of cardiovascular risk and on distribution in cardiovascular risk categories in 715 coeliac patients.

RESULTS

Compared to baseline, significant increases were found in body mass index (21.4±3.4 vs. 22.5±3.5; p<0.0001), total cholesterol (171.2±37.4mg/dL vs. 181.4±35.1mg/dL; p<0.0001), and γ-glutamyl transpeptidase (16.5±14.9 vs. 19.5±19.2U/L; p<0.0001). Significant reductions were found in serum triglycerides (87.9±49.5 vs. 80.2±42.8mg/dL; p<0.0001) and homocysteine (16.9±9.6 vs. 13.3±8.0μmol/L; p=0.018) during gluten-free diet. The proportion of patients included in an arbitrarily defined category of "lowest cardiovascular risk profile" decreased from 58% at baseline to 47% during gluten-free diet.

CONCLUSIONS

A gluten-free diet significantly affects cardiovascular risk factors in coeliac patients, but changes do not consistently point towards worse or better risk profiles, thus suggesting that the diet is unlikely to be atherogenic.

Association between aldehyde dehydrogenase 2 polymorphisms and the incidence of diabetic retinopathy among Japanese subjects with type 2 diabetes mellitus

Background

Mitochondrial aldehyde dehydrogenase 2 (ALDH2) detoxifies reactive aldehydes in the micro- and macrovasculature. These substrates, including methylglyoxal and 4-hydroxynonenal formed from glucose and lipids, cause protein carbonylation and mitochondrial dysfunction, forming advanced glycation end products (AGEs). The present study aimed to confirm the association between the inactive ALDH2*2 allele and diabetic retinopathy (DR).

Methods

A retrospective longitudinal analysis was conducted, among 234 Japanese patients with type 2 diabetes mellitus (DM) (156 males and 78 females) who had no DR signs at baseline and were treated for more than half a year. The ALDH2*1/*2 alleles were determined using a real-time TaqMan allelic discrimination assay. Multivariate-adjusted hazard ratios (HRs) and 95% confidential intervals (CIs) for the cumulative incidence of the development of DR were examined using a Cox proportional hazard model, taking drinking habits and the serum γ-glutamyltransferase (GGT) level into consideration.

Results

The frequency of the ALDH2*2 allele was 22.3%. Fifty-two subjects cumulatively developed DR during the follow-up period of 5.5 ± 2.5 years. The ALDH2*2 allele carriers had a significantly higher incidence of DR than the non-carriers (HR: 1.92; P = 0.02). The incidence of DR was significantly higher in the drinkers with the ALDH2*2 allele than in those with the ALDH2*1/*1 genotype (HR: 2.61; P = 0.03), while the incidence of DR in the non-drinkers did not differ significantly between the ALDH2 genotype groups (P > 0.05). The incidence of DR was significantly higher in the ALDH2*2 allele carriers with a high GGT level than in the non-carriers with a high or low GGT level (HR: 2.45; P = 0.03; and HR: 2.63; P = 0.03, respectively).

Conclusions

To the best of our knowledge, this is the first report of a significant association between the ALDH2*2 allele and the incidence of DR. These findings provide additional evidence that ALDH2 protects both microvasculature and macrovasculature against reactive aldehydes generated under conditions of sustained oxidative stress, although further investigations in larger cohorts are needed to verify the results.

Plasma gamma-glutamyltransferase is strongly determined by acylation stimulating protein levels independent of insulin resistance in patients with acute coronary syndrome

Background. Steatosis is a manifestation of the metabolic syndrome often associated with release of liver enzymes and inflammatory adipocytokines linked to cardiovascular risk. Gamma-glutamyltransferase (GGT) is one sensitive liver marker recently identified as an independent cardiovascular risk factor. Mechanisms involved in enhanced hepatic lipogenesis causing steatosis are not yet identified and are usually linked to insulin resistance (IR). Acylation stimulating protein (ASP), a potent lipogenic factor, was recently shown to increase in patients with steatosis and was implicated in its pathogenesis. Aim. To investigate the association of plasma ASP levels with liver and metabolic risk markers in acute coronary syndrome (ACS) patients. Methods. 28 patients and 30 healthy controls were recruited. Their anthropometrics, lipid profile, liver markers, insulin, and ASP levels were measured. Results. In the patients, ASP, liver, and metabolic risk markers were markedly higher than in the controls. ASP strongly predicted GGT levels (B = 0.75, P < 0.0001), followed by triglycerides (B = 0.403, P = 0.017), together determining 57.6% variation in GGT levels. Insulin and IR correlated with metabolic risk components but not with liver enzymes. Conclusion. The strong association of ASP with GGT in ACS patients suggests that ASP, independent of IR, may contribute to a vicious cycle of hepatic lipogenic stimulation and GGT release promoting atherogenesis.

Comparison of the relationships of alcoholic and nonalcoholic fatty liver with hypertension, diabetes mellitus, and dyslipidemia

We compared the relationships of alcoholic fatty liver and nonalcoholic fatty liver with hypertension, diabetes mellitus, and dyslipidemia. Using a nationwide Japanese survey, we collected data on subjects with biopsy-proven alcoholic fatty liver or nonalcoholic fatty liver. Multiple logistic regression analysis was performed to determine whether alcoholic fatty liver and nonalcoholic fatty liver are associated factors for these diseases. Data on 191 subjects (65, alcoholic fatty liver; 126, nonalcoholic fatty liver) were analyzed. Alcoholic fatty liver (odds ratio, 2.54; 95% confidence interval, 1.06–6.32; p = 0.040), age ≥55 years, and body mass index ≥25 kg/m² were correlated with hypertension, whereas nonalcoholic fatty liver (odds ratio, 2.32; 95% confidence interval, 1.08–5.20; p = 0.035) and serum γ-glutamyl transpeptidase levels ≥75 IU/l were correlated with dyslipidemia. Furthermore, we found that there were biological interactions between alcoholic fatty liver and body mass index ≥25 kg/m² in ≥55-year-old subjects (attributable proportion due to interaction, 0.68; 95% confidence interval, 0.19–1.17), as well as between alcoholic fatty liver and age ≥55 years in subjects with body mass index ≥25 kg/m² (attributable proportion due to interaction, 0.71; 95% confidence interval, 0.24–1.18). Alcoholic fatty liver was more strongly associated with hypertension than nonalcoholic fatty liver and nonalcoholic fatty liver was more strongly associated with dyslipidemia than alcoholic fatty liver. Moreover, alcoholic fatty liver, obesity, and older age may interact to influence hypertension status.

Gamma-glutamyltransferase and risk of cardiovascular disease mortality in people with and without diabetes: pooling of three British Health Surveys

BACKGROUND & AIMS

The relation between gamma-glutamyltransferase (GGT) and mortality risk has been little explored in people with diabetes. We examined (a) the association of GGT with cardiovascular disease (CVD) and all-cause mortality in people with and without diabetes; and (b) the predictive validity observed when adding GGT to a CVD risk algorithm.

METHODS

Participants were 17,852 adults from three British cohorts representative of the general population in England (N=1) and Scotland (N=2). Follow-up was to December 2009 (Scottish cohorts) and February 2008 (English cohort). Cox models were used to compute the hazard ratio (HR) and 95% confidence interval (95% CI) for a standard deviation (SD) increase log(e)(GGT) in relation to mortality according to diabetes status. The value of adding GGT to a CVD risk engine was assessed through c-statistic and relative integrated discrimination improvement.

RESULTS

In an analytical sample of 17,852 participants, 583 (3.3%) had baseline diabetes. During 10.1 years of follow-up, there were 235 deaths from all causes (77 from CVD) in diabetics. Corresponding results for non-diabetics were 2859 and 719. The age- and sex-adjusted HR (95%CI) for a one SD increase in log(e)(GGT) in relation to CVD mortality risk in participants with diabetes was 1.43 (1.13-1.81) and in those without diabetes was 1.27 (1.18-1.37). Corresponding results for total mortality were 1.24 (1.08-1.44) and 1.30 (1.25-1.34). Thus, there was no evidence that diabetes status modified the strength of the GGT-mortality relationship (p value for interaction ≥0.16). Adding GGT to model with classical predictors only marginally enhanced the prediction of CVD in both people with and without diabetes.

CONCLUSIONS

Higher GGT levels are a risk factor for all-cause and cardiovascular disease death in people with and without diabetes. However, knowledge of GGT does not improve cardiovascular predictions beyond traditional risk factors.

γ-Glutamyltranspeptidases: sequence, structure, biochemical properties, and biotechnological applications

γ-Glutamyltranspeptidases (γ-GTs) are ubiquitous enzymes that catalyze the hydrolysis of γ-glutamyl bonds in glutathione and glutamine and the transfer of the released γ-glutamyl group to amino acids or short peptides. These enzymes are involved in glutathione metabolism and play critical roles in antioxidant defense, detoxification, and inflammation processes. Moreover, γ-GTs have been recently found to be involved in many physiological disorders, such as Parkinson's disease and diabetes. In this review, the main biochemical and structural properties of γ-GTs isolated from different sources, as well as their conformational stability and mechanism of catalysis, are described and examined with the aim of contributing to the discussion on their structure-function relationships. Possible applications of γ-glutamyltranspeptidases in different fields of biotechnology and medicine are also discussed.

Cardioprotective effect of a combination of Rho-kinase inhibitor and p38 MAPK inhibitor on cardiovascular remodeling and oxidative stress in Dahl rats

AIM

Rho-kinase plays a critical role in various cellular functions. p38 mitogen-activated protein kinase (p38 MAPK) plays a central role in the inflammatory cytokine response to immune challenge. We evaluated the effects of a combination of fasudil, a Rho-kinase inhibitor, and FR167653, a p38 MAPK inhibitor, on cardiovascular remodeling, inflammation, and oxidative stress in Dahl salt-sensitive hypertensive (DS) rats.

METHODS

DS and Dahl salt-resistant (DR) rats were fed a high-salt diet at 6 weeks of age. Vehicle, fasudil (100 mg/kg per day), FR167653 (2 mg/kg per day), and a combination of fasudil and FR167653 were administered to 6-week-old DS rats for 5 weeks.

RESULTS

At the age of 11 weeks, in the left ventricle, DS rats were characterized by increased myocardial fibrosis, phosphorylation of p38 MAPK, and myosin phosphatase targeting subunit (MYPT-1), and NAD(P)H oxidase p22(phox), p47(phox), gp91(phox), tumor necrosis factor-α and interleukin-1β expression compared with DR rats. Fasudil improved cardiovascular remodeling, inflammation, NAD(P)H oxidase subunits, and phosphorylation of p38 MAPK and MYPT-1. FR167653 also similarly ameliorated these indices but not MYPT-1 phosphorylation. Compared with either agent alone, a combination of fasudil and FR167653 was more effective for the improvement of myocardial damage, inflammation and oxidative stress.

CONCLUSION

These findings suggest that the Rho-kinase and p38 MAPK pathways may play a pivotal role in ventricular hypertrophy; thus, we obtained the first evidence that a combination of Rho-kinase inhibitor and p38 MAPK inhibitor may provide a potential therapeutic target in hypertension with cardiovascular remodeling.