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Several γ-glutamyl compounds produced from gamma-glutamyltranspeptidase (GGT) have alluring features for food, pharmaceutical, and biotechnology applications. GGT from Bacillus altitudinis IHB B1644 was cloned, followed by an expression in pET-47b(+) Escherichia coli BL21(DE3). Recombinant GGT (Ba GGT) gene subsisted of 1755 bp encoding protein with 585 amino acids, predicted molecular weight, and theoretical pI of 63.3 kDa, and 4.92, respectively. Ectopic expression resulted in inclusion bodies formation at 37 °C. The protein was solubilized and different strategies like dialysis, rapid dilution, and on-column refolding were tried to get active recombinant protein (Ba GGT 1). To get protein in soluble fraction, GGT was over expressed at low temperature (20 °C), and IPTG concentration (0.025 mM) (Ba GGT 2). The heterodimeric enzyme consisted of molecular weight of 40, and 22 kDa for large and small subunits, respectively. The specific activities for Ba GGT 1 and Ba GGT 2 were 263.9, and 497.45 U mg−1, respectively. Ba GGT 1 and Ba GGT 2 showed optimum temperature, and pH at 37 °C and 9, respectively. K m values of 0.8 and 0.2 mM, and V max of 666.67 and 333.33 U mg−1 of protein, were calculated for Ba GGT 1 and Ba GGT 2 , respectively. The results demonstrate potential of Ba GGT in biosynthesis of γ-glutamyl compounds with industrial application. [Display omitted] • Bacillus altitudinis IHBB1644 studied for γ-glutamyltranspeptidase(GGT) expression. • Expression was performed at 37 °C,0.5 mM (BaGGT1) IPTG and 20 °C, 0.025 mM (BaGGT2). • Optimum GGT activity was observed at 37 °C and pH 9. • Difference in kinetic parameters was observed for BaGGT1 and BaGGT2. • BaGGT could be a potential candidate for industrial GGT production. [ABSTRACT FROM AUTHOR]

Objective: ɤ-glutamyltranspeptidase is an enzyme expressed in various malignancies including lung cancer. It rapidly activates non-fluorescent ɤ-glutamyl hydroxymethyl rhodamine green to highly fluorescent hydroxymethyl rhodamine green. The resultant tumor fluorescence is therefore an indicator of cellular ɤ-glutamyltranspeptidase activity. We have explored the use of ɤ-glutamyl hydroxymethyl rhodamine green as an intraoperative imaging tool for visualizing cancers. Herein, we evaluated the potential of the tumor fluorescence as a postoperative prognostic indicator. Methods: We included patients with non-small cell lung cancer who had undergone radical resection from 2012 to 2014 in the study. We assessed the fluorescence intensity of the resected tumor and normal lung tissue by ex vivo imaging using ɤ-glutamyl hydroxymethyl rhodamine green. Results: Sixty-seven patients were eligible for the study (adenocarcinomas, n = 44; squamous cell carcinoma, n = 14; other histologies, n = 8). The pathological stages were I, II, III, and IV in 39, 15, 12, and 1 patient, respectively. Based on the fluorescence of the tumor tissue, the patients were divided into high fluorescence (n = 33) and low fluorescence (n = 34) groups. The 5-year overall survival rate was significantly higher in the high fluorescence group (72.7%) compared to the low fluorescence group (47.1%, P = 0.025). Similarly, pathological stage I patients of the high fluorescence group had higher 5-year overall survival (85.7% vs. 44.4%, P = 0.009) and recurrence-free survival (76.2% vs. 44.4% P = 0.044) rates compared to those of the low fluorescence group. Conclusions: ɤ-glutamyl hydroxymethyl rhodamine green fluorescence is a good postoperative prognostic indicator in patients with non-small cell lung cancer. [ABSTRACT FROM AUTHOR]

Background: This study aimed to compare the diagnostic performance of carbohydrate-deficient transferrin (CDT) and gamma-glutamyltranspeptidase (γ-GTP) to assess the single and combined benefits of these biological markers for the detection of chronic excessive alcohol consumption in patients with alcoholic cirrhosis. Methods: Biological markers were determined in blood samples from patients with alcoholic cirrhosis (drinking group, n = 35; nondrinking group, n = 81). The prediction accuracy of %CDT alone, γ-GTP alone, and their combination for the detection of excessive alcohol consumption was determined in patients with alcoholic cirrhosis. Results: Serum total bilirubin, alanine aminotransferase, aspartate aminotransferase, γ-GTP, and alkaline phosphatase levels and %CDT were significantly higher and serum albumin levels were significantly lower in the drinking group than in the nondrinking group. The combination of %CDT and γ-GTP compared with %CDT or γ-GTP alone showed a higher prediction accuracy. The combination of %CDT and γ-GTP exhibited a higher specificity than γ-GTP alone. However, in terms of sensitivity, no significant difference was found between single or combined markers. Conclusions: The combination of %CDT and γ-GTP is considered a useful biomarker of chronic excessive alcohol consumption in patients with alcoholic cirrhosis.

Extracellular protease Vpr (Vpr), gamma-glutamyltranspeptidase (GGT; EC 2.3.2.2) and glyoxal/methylglyoxal reductase (YvgN; EC 1.1.1.21) are extracellular enzymes involved in feather degradation, which were identified by secretome analyses from an efficient feather-degrading strain Bacillus subtilis CH-1. The encoding sequences corresponding to the three secretory enzymes were cloned into vector pET22b for recombinant expression in Escherichia coli strain BL21 (DE3). Afterward, the proteins containing the C-terminal His-tag were purified using a Ni-IDA column. The optimal temperatures and pH values for protease activity of recombinant Vpr, GGT, and YvgN were identified as 45 °C/pH 7.0, 40 °C/pH 8.0, and 50 °C/pH 6.0 respectively when casein is the substrate. Furthermore, the synergistic effects of the three enzymes were studied using feather powder as substrate. Vpr was the core enzyme to hydrolyze keratin, while GGT and YvgN were coenzymes providing reducing activities for keratin decomposition. The keratinolytic activity was enhanced to about 1.4-folds when YvgN and Vpr applied together in comparison to Vpr alone. And the keratinolytic activity almost reached to 1.5-folds when all the three enzymes were combined to use. The study provides a novel perspective of the mechanism of keratin degradation by microorganisms, and thereby may also be of relevance for the design of an industrial process for enzymatic keratin degradation; however, additional experiments must be done to substantiate this conclusion. [ABSTRACT FROM AUTHOR]

Significance: Glutathione degradation has for long been thought to occur only on noncytosolic pools. This is because there has been only one enzyme known to degrade glutathione (γ-glutamyl transpeptidase) and this localizes to either the plasma membrane (mammals, bacteria) or the vacuolar membrane (yeast, plants) and acts on extracellular or vacuolar pools. The last few years have seen the discovery of several new enzymes of glutathione degradation that function in the cytosol, throwing new light on glutathione degradation. Recent Advances: The new enzymes that have been identified in the last few years that can initiate glutathione degradation include the Dug enzyme found in yeast and fungi, the ChaC1 enzyme found among higher eukaryotes, the ChaC2 enzyme found from bacteria to man, and the RipAY enzyme found in some bacteria. These enzymes play roles ranging from housekeeping functions to stress responses and are involved in processes such as embryonic neural development and pathogenesis. Critical Issues: In addition to delineating the pathways of glutathione degradation in detail, a critical issue is to find how these new enzymes impact cellular physiology and homeostasis. Future Directions: Glutathione degradation plays a far greater role in cellular physiology than previously envisaged. The differential regulation and differential specificities of various enzymes, each acting on distinct pools, can lead to different consequences to the cell. It is likely that the coming years will see these downstream effects being unraveled in greater detail and will lead to a better understanding and appreciation of glutathione degradation. Antioxid. Redox Signal. 27, 1200-1216. [ABSTRACT FROM AUTHOR]

O efeito de dietas à base de arroz-feijão sobre a atividade plasmática e hepática da gama-glutamiltranspeptidase-GGT foi avaliado em ratos jovens (Experimento A) e adultos (Experimento B). Os animais receberam dietas isocalóricas contendo três níveis de proteína de Arroz, Feijão, Arroz-Feijão ou Caseína, durante 28 dias. Com os menores níveis distintos de proteína dietética, a atividade plasmática e hepática da GGT mostrou-se significativamente elevada em relação ao grupo controle de Caseína a 25%, assemelhando-se àquela do grupo aprotéico. Essa elevação foi mais efetiva com dietas de Feijão e Arroz-feijão em ratos jovens, evidenciando que o efeito da restrição protéica é exacerbado pela baixa disponibilidade de aminoácidos sulfurados, além de um efeito diferencial com a idade. As alterações observadas sugerem uma adaptação metabólica da GGT aos níveis inadequados de proteína e sobretudo de aminoácidos sulfurados e subsidiam a hipótese de redução no nível de glutátion com dietas à base de leguminosas.Rice and bean diets increase hepatic and plasmatic activity of gammaglutamyltranspeptidase in growing rats. The effect of feeding rice and bean diets in both hepatic and plasmatic activity of gamma-glutamyltranspeptidase-(GGT-EC 2.3.2.2) activity was evaluated in growing-rats (Experiment A) and mature rats (Experiment B). During 28 days, the animals were fed with isocaloric-diets composed by tree levels of rice, bean or rice-and-bean protein. Similarly with the aproteic group, a significant increase on both the hepatic and plasmatic GGT activity were showed with the lowest leves of protein, when compared with 25% casein control group. This rise was more effective in growing-rats fed on legume-based diets (as bean or rice-and-bean diets), making evident a differential effect of age and an exacerbated effect of the protein restriction with the lowest sulfur amino acids disposal. These alterations suggest a metabolic adaptation of GGT to both the inadequate protein and sulfur-amino acid levels, thus supporting the hypothesis that the Glutathione levels may be reduced by these legume-based diets.

The determination of enzyme activity in the organism's humours or in different tissues is an important means of detecting and following the evolution of numerous pathological states. In our study we have determined the activity of some cytolysis enzymes (lactate dehydrogenase, LDH; alanine-aminotransferase or glutamic-pyruvic transaminase, GPT; aspartate aminotransferase or glutamic-oxaloacetic transaminase, GOT; creatine kinase, CK and gammaglutamyltranspeptidase, GGT) on patients with acute coronary syndromes: angina pectoris (AP), chronic painful ischemic heart disease (CPIHD), arterial hypertension (HTN), arterial hypertension with chronic painful ischemic heart disease (HTN+CPIHD) and acute myocardial infarction (AMI). The results show that the levels of activity of cytolysis enzymes are different in patients with acute coronary syndromes (ACS). The activity of LDH, GPT, GOT, CK and GGT do not have the same values for one and the same coronary disease measured in patients from different groups of age and sexes (male and female). [ABSTRACT FROM AUTHOR]

Abstract: The factors responsible for the conjunctivitis and iritis associated with acute ocular infection and post enteric inflammatory disease are not fully known. The pro-inflammatory activity of unilateral topical application of muramyl dipeptide (MDP; the smallest bio-active Gram-positive and Gram-negative bacterial cell wall component) was investigated in adult rabbits. The resultant bilateral conjunctivitis/iritis and pyogenic responses were characterized. Bilateral symptoms were graded by slit lamp examinations; tear fluid, Schirmer tests (tear production), blood and aqueous humor (AH) samples were obtained from MDP-treated and untreated rabbits. MDP concentration, gamma-glutamyltranspeptidase activity (GGT; key enzyme in glutathione recapture, xenobiotic detoxification, eicosanoid synthesis and neutrophil function), protein concentration, and tear cell density, cytology, and immunofluorescent antibody reactivity to GGT and calreticulin (CRT; MDP-binding protein) were determined. MDP was cleared from ipsilateral tears and serum by 6 h, but was undetected in mock-treated contralateral tears. Bilateral signs of acute transient pyogenic conjunctivitis, characterized by tearing, lid edema, conjunctival hyperemia, chemosis and leukocytic infiltrate with iritis (erythema and aqueous flare) were detected. Milder symptoms occurred in the mock-treated contralateral eyes. Bilateral symptoms, tear production, tear protein, GGT activity, and mucopurulent discharge (containing up to 2.5–5.0 × 106 cells/mL) were elevated 4–8 h post MDP and resolved to near pre-treatment levels by 24 h. Tear GGT activity and protein levels were higher in MDP-treated and mock-treated contralateral eyes than in eyes of untreated adult rabbits (p's < 0.001). Elevated tear GGT activity was associated with histopathology and increased vascular and epithelial permeability to serum protein, GGT-positive epithelia cells, macrophages and heterophils. Repeat MDP applications induced recurrent induction and resolution patterns of bilateral conjunctivitis/iritis and tear GGT activity, but ipsilateral GGT responses were lower. The results suggest unilateral topical MDP application to adult rabbit eyes induces a bilateral acute pyogenic conjunctivitis/iritis (PCI) characterized by increased vascular and epithelial permeability similar to acute bacterial conjunctivitis in man. The detection of CRT/GGT positive heterophils in tears suggests efferocytosis (phagocytosis of dead/dying cells). Tear GGT activity may be a useful means to quantify MDP-induced toxicity and extraocular inflammation. [Copyright &y& Elsevier]

Context: High malaria burden has led to the increased use of insecticides in the tropics and subtropics. This study thus aimed at assessing the hematological effects alteration of pyrethroid insecticide exposure using the experimental animal model. Objective: A commonly available Electric Mosquito-Repellent Liquid pyrethroid insecticide containing prallethrin 1.6% w/w is widely used for mosquito control in Saudi Arabia. The immunotoxic effects after inhalation exposures to the preparation for a continuous period of 24, 48, and 72 h were investigated in rats. Methods and materials: Rats were exposed to prallethrin 1.6% w/w by inhalation for 72 consecutive hours. Total blood count, blood indices of creatine kinase (CK), gamma-glutamyltranspeptidase (γ-GT), superoxide dismutase (SOD), nitric oxide (NO), malondialdehyde (MDA), interleukin (IL)-2, tumor necrosis factors (TNF)α, alpha-fetoprotein (AFP), carbohydrate antigen (CA) 19.9 and carcinoembrionic antigen (CEA) were assayed. Results: The administration of prallethrin 1.6% w/w created significant increased changes in the levels of total WBC, lymphocytes, RBC, hemoglobin, packed cell volume, platelets, mean corpuscular volume, and mean corpuscular hemoglobin in rats after 24, 48, and 72 h of continuous inhalation; however, there was a significant reduction in neutrophils at transient reduction in the monocytes after 24 and 48 h to return to normal after 72 h. Significant increases in the levels of CK, γ-GT, SOD, NO, MDA, AFP, IL-2, and TNFα were recorded. CA and CEA did not exhibit any change. Conclusions: Continuous inhalation to prallethrin 1.6% insecticides poses toxicity on hematological variables. It is also concluded that pyrethroid group of insecticide may cause hematological, biochemical, cytokine disturbances and possible mutagenic damage to the tissues. [ABSTRACT FROM AUTHOR]

Abstract: Gamma-glutamyltransferase (GGT, EC 2.3.2.2) cleaves the γ-glutamyl linkage in glutathione (GSH). Three GGTs in the hemibiotrophic plant pathogen Colletotrichum graminicola were identified in silico. GGT mRNA expression was monitored by quantitative reverse-transcriptase PCR. Expression of all three genes was detected in planta during the biotrophic and necrotrophic stages of infection. Of the three GGTs, CgGGT1 mRNA (from gene GLRG_09590) was the most highly expressed. All three GGT mRNAs were up-regulated in wild type nitrogen-starved germlings in comparison to non-starved germlings. CgGGT1 was insertionally mutagenized in C. graminicola, complemented with the wild type form of the gene, and over-expressed. Enzyme assays of two independent CgGGT1 knockouts and the wild type indicated that CgGGT1 is the major GGT and accounts for 86% and 68% of total GGT activity in conidia and mycelia, respectively. The over-expressing strain had 8-fold and 3-fold more enzyme activity in conidia and mycelia, respectively, than the wild type. In an analysis of the GGT knockout, complemented and over-expressing strains, GGT1 transcript levels are highly correlated (r =0.95) with levels of total GGT enzyme activity. CgGGT1 and CgGGT2 genes in strains that had ectopic copies of CgGGT1 were not up-regulated by nitrogen-starvation, in contrast to the wild type. Deletion or over-expression of CgGGT1 had no effect on mRNA expression of CgGGT2 and CgGGT3. In broth in which 3 and 6mM glutathione (GSH) was the nitrogen source, the CgGGT1 over-expressing strain produced significantly (P <0.0001) more biomass than the wild type and complemented strains, whereas the CgGGT1Δ strains produced significantly (P <0.0001) less biomass than the wild type strain. This suggests that CgGGT1 is involved in utilizing GSH as a nitrogen source. However, deletion and over-expression of CgGGT1 had no effect on either virulence in wounded corn leaf sheaths or GSH levels in conidia and mycelia. Thus, the regulation of GSH concentration is apparently independent of CgGGT1 activity. [Copyright &y& Elsevier]

Gamma-glutamyltransferase (GGT, EC 2.3.2.2) cleaves the γ-glutamyl linkage in glutathione (GSH). Ascomycetes in either the Saccharomycotina or the Taphrinomycotina have one to three GGTs, whereas members of the Pezizomycotina have two to four GGTs. A Bayesian analysis indicates there are three well-supported main clades of GGTs in the Ascomycota. 1) A Saccharomycotina and a Taphrinomycotina-specific GGT sub-clade form a yeast main clade. This clade has the three relatively well-characterized fungal GGTs: ( Saccharomyces cerevisiae CIS2 and Schizosaccharomyces pombe Ggt1 and Ggt2) and most of its members have all 14 of the highly conserved and critical amino acids that are found in GGTs in the other kingdoms. 2) In contrast, a main clade (GGT3) differs in 11 of the 14 highly conserved amino acids that are found in GGTs in the other kingdoms. All of the 44 Pezizomycotina analyzed have either one or two GGT3s. 3) There is a Pezizomycotina-only GGT clade that has two well-supported sub-clades (GGT1 and GGT2); this clade differs in only two of the 14 highly conserved amino acids found in GGTs in the other kingdoms. Because the Pezizomycotina GGTs differ in apparently critical amino acids from the cross-kingdom consensus, a putative GGT from Colletotrichum graminicola, a member of the Pezizomycotina, was cloned and the protein product was expressed as a secreted protein in Pichia pastoris. A GGT enzyme assay of the P. pastoris supernatant showed that the recombinant protein was active, thereby demonstrating that CgGGT1 is a bona fide GGT. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Recent large epidemiologic population-based studies identified gamma-glutamyltransferase (GGT) as a marker for increased cervical cancer incidence. Furthermore, high levels of GGT seem to increase the risk of progression of high-grade cervical dysplasia to invasive carcinoma. Therefore, we evaluated the association between pre-therapeutic serum GGT levels, tumor stage and prognosis in patients with cervical cancer. Materials and methods: In this multi-center trial, pre-therapeutic GGT levels were examined in 692 patients with cervical cancer. GGT levels were correlated with clinico-pathological parameters. Patients were assigned to previously described GGT risk groups and uni- and multivariable survival analyses were performed. Results: GGT serum levels were associated with FIGO stage (p <0.0001) and age (r=0.2, p <0.0001) but not with lymph node involvement (p =0.85), and histological type (p =0.98). High-risk GGT group affiliation (p =0.01 and p <0.0001) was associated with poor disease-free and overall survival in a univariate analysis, but not in a multivariable Cox-regression model (p =0.59 and p =0.171). We further investigated the association between prognosis and GGT and observed a linear correlation between GGT and prognosis. Therefore we were not able to identify a clear prognostic cut-off value for GGT in patients with cervical cancer. Conclusions: High GGT – a marker for apoptosis and cervical cancer risk – is associated with advanced tumor stage in patients with cervical cancer. [Copyright &y& Elsevier]

Abstract: Gamma-glutamyltranspeptidases (γ-GTs) catalyze the transfer of the gamma-glutamyl moiety of glutathione and related gamma-glutamyl amides to water (hydrolysis) or to amino acids and peptides (transpeptidation) and play a key role in glutathione metabolism. Recently, γ-GTs have been considered attractive pharmaceutical targets for cancer and useful tools to produce γ-glutamyl compounds. To find out γ-GTs with special properties we have chosen microorganisms belonging to Geobacillus species which are source of several thermostable enzymes of potential interest for biotechnology. γ-GT from Geobacillus thermodenitrificans (GthGT) was cloned, expressed in Escherichia coli, purified to homogeneity and characterized. The enzyme, synthesized as a precursor homotetrameric protein of 61-kDa per subunit, undergoes an internal post-translational cleavage of the 61 kDa monomer into 40- and 21-kDa shorter subunits, which are then assembled into an active heterotetramer composed of two 40- and two 21-kDa subunits. The kinetic characterization of the hydrolysis reaction using l-glutamic acid γ-(4-nitroanilide) as the substrate reveals that the active enzyme has Km 7.6 μM and V max 0.36 μmol min/mg. The optimum pH and temperature for the hydrolysis activity are 7.8 and 52 °C, respectively. GthGT hydrolyses the physiological antioxidant glutathione, suggesting an involvement of the enzyme in the cellular defense mechanism against oxidative stress. Unlike other γ-GTs, the mutation of the highly conserved catalytic nucleophile, Thr353, abolishes the post-translational cleavage of the pro-enzyme, but does not completely block the hydrolytic action. Furthermore, GthGT does not show any transpeptidase activity, suggesting that the enzyme is a specialized γ-glutamyl hydrolase. The GthGT homology-model structure reveals peculiar structural features, which should be responsible for the different functional properties of the enzyme and suggests the structural bases of protein thermostability. [Copyright &y& Elsevier]

Introduction: Hepatocellular carcinoma (HCC) is one of the complications associated with liver cirrhosis (LC). The main objective of the present study was to describe the levels of the serological markers alpha-fetoprotein (AFP) and gamma-glutamyltranspeptidase (GGT) in patients with LC and/or HCC. Methods: Cross sectional study that included 99 patients with a diagnosis of LC and/or HCC. Results: 66 (66.7%) patients had a diagnosis of LC, 23 (23.2%) had LC alongside with HCC and 10 (10.1%) had HCC without LC. AFP levels were higher in individuals with HCC associated with LC when compared with those with LC only (20 and 2.93 ng/ mL, p <0.05), the levels of GGT were also higher in patients with HCC associated with LC (208 and 109 IU/L, p <0.05). Not a single patient with HCC had normal levels of AFP and GGT simultaneously. Conclusions: In patients with HCC associated with LC levels of AFP and GGT were significantly higher than those found in individuals with LC only. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this work was to analyze the effect of diets that contain several oils whose composition in fatty acids were different, on the kinetic parameters of the gamma-glutamyltranspeptidase (GGTP) and the lipoperoxidation of the epididymis because GGTP controls the level of the glutathione that is an molecule that regulates the level of oxidation protecting the maturation and survival of sperm in the lumen of the epididymis. The caput portion of the epididymis was chosen because the epithelium of this segment synthesizes GGTP. Weaned BALB-c mice were fed a commercial or semi-synthetic diet that contained 5% added olein. The mice were maintained on corn oil or fish oil diet for the first 4–8 months of age. The kinetic variables of the GGTP enzyme, analyzed by means of multiple regression analysis using dummy variables, showed that values were similar in olein and corn oil samples, whereas in samples from the fish oil fed group the enzyme behaved as that in animals maintained on commercial diets. Although there were no variations in maximum velocity (V m) of the enzyme, the K m value, was greater (P <0.0001) for the mice fed the olein and corn diets. These groups contained greater percentages of the monounsaturated fatty acids, palmitoleic (16:1 n-7) and oleic acid, 18:1 n-9. Similarly, the amount of lipid peroxidation was also greater in the olein and corn oil groups with respect to commercial and fish groups. The significant increment in K m of GGTP in the olein and corn groups was correlated with greater amount of monounsaturated fatty acids and lipid peroxidation in the epididymis. In conclusion, modifications of dietary lipid sources differentially modulated the epididymis tissue fatty acid profile, lipid peroxidation amounts, and the K m of GGTP. These effects may alter the metabolism of the natural substrate of GGTP, glutathione, a tripeptide with a powerful antioxidant activity, which is necessary in maintaining the oxidative state of the sperm microenvironment, thereby favoring maturation of the male gametes. [Copyright &y& Elsevier]

Abstract: Gamma-glutamyltranspeptidase (GGT) is a well known cell plasma membrane and serum circulating enzyme. In clinical chemistry, GGT is used as a marker of alcohol consumption and drug uptake. Serum GGT activity varies in hepatobiliary diseases and cancer. This enzyme is involved in glutathione (GSH) metabolism, which is generally associated with antioxidant properties. However, in recent years, findings from our group and from others showed that GGT-catalysed extracellular metabolism of GSH leads, in the presence of iron, to the generation of reactive oxygen species (ROS). It was demonstrated that those highly reactive species oxidise lipids, cell surface protein thiols or activate transcriptional factors such as Nuclear Factor κB (NFκB). The objective of the present work is to determine whether the red blood cells are targets for plasma GGT-initiated pro-oxidant reaction. The results obtained demonstrate that the GGT/GSH/iron system oxidises isolated erythrocyte membranes. A significant release of haemoglobin and a decrease of erythrocyte deformability are also observed. In addition, in vivo studies showed a relationship between plasma GGT activity and erythrocyte deformability in 20 studied subjects. In conclusion, GGT-mediated ROS production is able to oxidise erythrocytes and thus disturbs their functions. [ABSTRACT FROM AUTHOR]

The pharmacokinetics of norethisterone have been studied in 8 women during and one month after treatment with rifampicin (450-600 mg/day). Rifampicin caused a significant reduction in the A. U. C. of a single dose of 1 mg norethisterone from 37.8±13.1 to 21.9±5.9 ng/ml X h (p<0.01). The plasma norethisterone half life (β-phase) was also reduced from 6.2±1.7 to 3.2±1.0 h (p<0.0025). In one additional woman on long term oral contraceptive therapy the 12 hour plasma norethisterone concentration was reduced by rifampicin from 12.3 ng/ml to 2.3 ng/ml. Rifampicin caused a significant increase in antipyrine clearance, 6β-hydroxycortisol excretion and plasma gamma-glutamyltranspeptidase activity but there were no significant correlations between changes in these indices of liver microsomal enzyme induction. There was a significant correlation between the percentage increase in antipyrine clearance and the percentage decrease in norethisterone A. U. C. during rifampicin. The changes in norethisterone pharmacokinetics during rifampicin therapy are compatible with the known enzyme inducing effect of rifampicin. [ABSTRACT FROM AUTHOR]

The effect of phenobarbital (PB) on liver cells treated with 3′-methyl-4-dimethylaminoazobenzene (3′-Me-DAB) was studied using primary cultures of normal adult rat liver cells. Following a 1-day attachment period, primary liver cell cultures were treated with 0.24 m M 3′-Me-DAB for 6 days, and then treated with or without PB at 0.75, 1.5 and 3 m M for 19 days. Similarly, control cultures were treated with 0.5% dimethylsulfoxide (DMSO), a solvent for 3′-Me-DAB, for 6 days, and then treated with or without PB in the same way. Each treatment was done on 8 cultures. Chromosome analysis and cytochemical assay for gamma-glutamyltranspeptidase (GGT) activity were carried out on the carcinogen-treated and control cultures between 1 and 2 months after initiation of primary culture. Chromosomal abnormalities were detected in 23 of 32 carcinogen-treated cultures and also in 2 of 28 control cultures tested. However, GGT positive cells were detected only in the carcinogen-treated cultures at a frequency of 22/32. Of the 23 carcinogen-treated cultures with chromosomal abnormalities, 18 contained GGT positive cells. These results show a good correlation between chromosomal abnormality and acquisition of GGT activity at culture dish level. Furthermore, in the carcinogen-treated cultures, PB treatment caused a dose-dependent increase in the number of GGT positive cultures and in the percentage of GGT positive cells in each culture, and also caused a dose-dependent increase in the number of cultures with chromosomal abnormalities. [ABSTRACT FROM AUTHOR]

The risk of developing gastric cancer is strongly linked to Helicobacter pylori (H. pylori) infection. Alternatively, autophagy is a conserved response that is important in cellular homeostasis and provides protection against bacterial infections. Although H. pylori is typically considered an extracellular bacterium, several reports indicate that it internalizes, possibly to avoid exposure to antibiotics. Mechanisms by which H. pylori manipulates host cell autophagic processes remain unclear and, importantly, none of the available studies consider a role for the secreted H. pylori virulence factor gamma-glutamyltranspeptidase (HpGGT) in this context. Here, we identify HpGGT as a novel autophagy inhibitor in gastric cells. Our experiments revealed that deletion of HpGGT increased autophagic flux following H. pylori infection of AGS and GES-1 gastric cells. In AGS cells, HpGGT disrupted the late stages of autophagy by preventing degradation in lysosomes without affecting lysosomal acidification. Specifically, HpGGT impaired autophagic flux by disrupting lysosomal membrane integrity, which leads to a decrease in lysosomal cathepsin B activity. Moreover, HpGGT was necessary for efficient internalization of the bacteria into gastric cells. This important role of HpGGT in internalization together with the ability to inhibit autophagy posits HpGGT as a key virulence factor in the development of gastric cancer. [ABSTRACT FROM AUTHOR]

O efeito de dietas à base de arroz-feijão sobre a atividade plasmática e hepática da gama-glutamiltranspeptidase-GGT foi avaliado em ratos jovens (Experimento A) e adultos (Experimento B). Os animais receberam dietas isocalóricas contendo três níveis de proteína de Arroz, Feijão, Arroz-Feijão ou Caseína, durante 28 dias. Com os menores níveis distintos de proteína dietética, a atividade plasmática e hepática da GGT mostrou-se significativamente elevada em relação ao grupo controle de Caseína a 25%, assemelhando-se àquela do grupo aprotéico. Essa elevação foi mais efetiva com dietas de Feijão e Arroz-feijão em ratos jovens, evidenciando que o efeito da restrição protéica é exacerbado pela baixa disponibilidade de aminoácidos sulfurados, além de um efeito diferencial com a idade. As alterações observadas sugerem uma adaptação metabólica da GGT aos níveis inadequados de proteína e sobretudo de aminoácidos sulfurados e subsidiam a hipótese de redução no nível de glutátion com dietas à base de leguminosas.

Aim: To assess the prognostic value of the pretreatment serum γ-glutamyltranspeptidase (GGT) level in patients with primary liver cancer (PLC). Methods: Relevant studies were systematically searched online on Web of Science, PubMed, and Embase databases published until 9 October 2018. The end points were overall survival (OS), recurrence-free survival (RFS), and disease-free survival (DFS). Meta-analysis was conducted using hazard ratio (HR), and its 95% confidence interval (CI) as effect measure. Results: A total of 33 eligible studies with 9238 patients with PLC were included in this meta-analysis. The synthesized analysis showed that that higher serum GGT level was significantly related to poorer OS (HR: 1.79, 95% CI: 1.66-1.93, P <0.01), RFS (HR: 1.60, 95% CI: 1.46-1.77, P <0.01), and DFS (HR: 1.52, 95% CI: 1.33-1.73, P <0.01) of patients with PLC. Subgroup analyses demonstrated that the negative prognostic impact of higher serum GGT level on OS and RFS was still of significance regardless of ethnicity, pathological type, sample size, cut-off value, first-line treatment, and analysis type. Conclusion: The pretreatment serum GGT might be a predictive factor of poor prognosis for PLC patients., (© 2018 The Author(s).)

Background and Aims: Insulin resistance and cytokine production are key mechanisms leading to fatty change in the liver and may produce nonalcoholic steatohepatitis (NASH). Oxidative stress may also contribute to clinical progression from simple fatty liver (FL) to NASH. A therapy for insulin resistance and antioxidant has been applied to treat NASH, yet these treatments are not fully established. In the present study, we have evaluated whether an antioxidant agent, glutathione, prevents the development of NASH from FL., Materials and Methods: Five patients with FL and 10 with NASH were enrolled in the study. Three hundred milligrams per day of glutathione was given orally to patients with nonalcoholic fatty liver disease (NAFLD) every day, and an oxidative stress marker and biochemical tests were analyzed before treatment and 1 and 3 months after starting the treatment. We measured serum levels of 8-hydroxy-2-deoxyguanosine (8-OHdG) and gamma-glutamyltranspeptidase (GGT). Immunohistochemistry for glutathione was performed on formalin fixed liver specimens obtained from liver biopsies., Results: Before treatment, the NASH group had higher serum 8-OHdG and lower serum glutathione levels than the FL group. Immunohistochemistry revealed that a strong expression of glutathione was observed in zone 3 in both NASH and FL before treatment. Serum levels of alanine transaminase and 8-OHdG were significantly decreased after treatment in the NASH group. Gamma-glutamyltranspeptidase was decreased after treatment, although the decrease was statistically not significant., Discussion: The present pilot study demonstrated that antioxidant therapy with glutathione may reduce the pathological oxidative stress in the liver in NASH, preventing the progression from NAFLD to NASH., How to Cite This Article: Irie M, Sohda T, Anan A, Fukunaga A, Takata K, Tanaka T, Yokoyama K, Morihara D, Takeyama Y, Shakado S, Sakisaka S. Reduced Glutathione suppresses Oxidative Stress in Nonalcoholic Fatty Liver Disease. Euroasian J Hepato-Gastroenterol 2016;6(1):13-18., Competing Interests: Source of support: Nil Conflict of interest: None

Abstract: Both elevated liver enzymes and a family history of diabetes mellitus (FHDM) are independent risk factors for type 2 diabetes. This study evaluates the epidemiological association between elevated liver enzymes and FHDM. Subjects included 3512 women workers without diabetes, hepatitis, a smoking habit, or a history of alcohol intake. Blood samples and personal data were collected from all subjects. Subjects with FHDM had a higher mean body mass index (BMI: 23.9kg/m2 vs. 23.4kg/m2; p =0.003). Laboratory testing also revealed higher mean fasting plasma glucose (FPG: 5.67mmol/L vs. 5.22mmol/L; p <0.001), asparate aminotransferase (AST: 20.0IU/L vs. 19.2IU/L; p =0.049), alanine aminotransferase (ALT: 18.4IU/L vs. 16.7IU/L; p =0.004), gamma-glutamyltranspeptidase (GGT: 24.1IU/L vs. 20.5IU/L; p <0.001), and triglycerides (TG: 1.09mmol/L vs. 1.00mmol/L; p =0.011) for FHDM subjects, when adjusted for age and BMI. Multiple linear regression analysis revealed that FHDM, age, BMI, FPG, and TG were correlated with GGT (p =0.004 for FHDM; p <0.001 for age, BMI, FPG, and TG). Elevated liver enzymes were associated with FHDM. In particular, elevated GGT was related to FHDM, independent of the other variables. Elevated liver enzymes, probably due to fat deposition in the liver, may play a role in increasing the risk of diabetes in individuals with FHDM. [Copyright &y& Elsevier]

The enzyme γ-glutamyltranspeptidase 1 (GGT1) is a conserved member of the N-terminal nucleophile hydrolase family that cleaves the γ-glutamyl bond of glutathione and other γ-glutamyl compounds. In animals, GGT1 is expressed on the surface of the cell and has critical roles in maintaining cysteine levels in the body and regulating intracellular redox status. Expression of GGT1 has been implicated as a potentiator of asthma, cardiovascular disease, and cancer. The rational design of effective inhibitors of human GGT1 (hGGT1) has been delayed by the lack of a reliable structural model. The available crystal structures of several bacterial GGTs have been of limited use due to differences in the catalytic behavior of bacterial and mammalian GGTs. We report the high resolution (1.67 Å) crystal structure of glutamate-bound hGGT1, the first of any eukaryotic GGT. Comparisons of the active site architecture of hGGT1 with those of its bacterial orthologs highlight key differences in the residues responsible for substrate binding, including a bimodal switch in the orientation of the catalytic nucleophile (Thr-381) that is unique to the human enzyme. Compared with several bacterial counterparts, the lid loop in the crystal structure of hGGT1 adopts an open conformation that allows greater access to the active site. The hGGT1 structure also revealed tightly bound chlorides near the catalytic residue that may contribute to catalytic activity. These are absent in the bacterial GGTs. These differences between bacterial and mammalian GGTs and the new structural data will accelerate the development of new therapies for GGT1-dependent diseases.