Peroxiredoxins and Hypoxia-Inducible Factor-1α in Duodenal Tissue: Emerging Factors in the Pathophysiology of Pediatric Celiac Disease Patients.

Celiac disease (CD) is an autoimmune enteropathy. Peroxiredoxins (PRDXs) are powerful antioxidant enzymes having an important role in significant cellular pathways including cell survival, apoptosis, and inflammation. This study aimed at investigating the expression levels of all PRDX isoforms (1-6) and their possible relationships with a transcription factor, HIF-1α, in the small intestinal tissue samples of pediatric CD patients. The study groups consisted of first-diagnosed CD patients (n = 7) and non-CD patients with functional gastrointestinal tract disorders as the controls (n = 7). The PRDXs and HIF-1α expression levels were determined by using real-time PCR and Western blotting in duodenal biopsy samples. It was observed that the mRNA and protein expression levels of PRDX 5 were significantly higher in the CD patients, whereas the PRDX 1, -2, and -4 expressions were decreased in each case compared to the control group. No significant differences were detected in the PRDX 3 and PRDX 6 expressions. The expression of HIF-1α was also significantly elevated in CD patients. These findings indicate, for the first time, that PRDXs, particularly PRDX 5, may play a significant role in the pathogenesis of CD. Furthermore, our results suggest that HIF-1α may upregulate PRDX-5 transcription in the duodenal tissue of CD.

Design, synthesis, and biological activity studies on benzimidazole derivatives targeting myeloperoxidase.

Myeloperoxidase (MPO) plays a key role in human antimicrobial system by oxidizing vital molecules of microorganisms in phagolysosomes through produced hypochlorous acid (HOCl). However, MPO can be released outside the phagocyte and produces reactive intermediates leading to tissue damage. MPO, as a local mediator of tissue damage, has been associated with inflammatory diseases such as renal injury, multiple sclerosis, cardiovascular and neurodegenerative diseases. Therefore, the enzyme currently draws attention as a potential therapeutic target. In this study, isomeric 1,3-dihydro-2H-benzo[d]imidazole-2-thione derivatives having amide, hydrazide and hydroxamic acid groups either on nitrogen or on sulphur atom were designed and their inhibitory activity was determined on chlorination and peroxidation cycles of MPO. Among the compounds, 2-(2-thioxo-2,3-dihydro-1H-benzo[d]imidazole-1-yl)acetohydrazide(C19) was found as the most active inhibitor on both cycles.

Oxidative and nitrosative stress markers in patients on hemodialysis and peritoneal dialysis.

AIM: The aim of this study was to evaluate the effects of hemodialysis (HD) and peritoneal dialysis (PD) treatments on oxidative and nitrosative stress markers comparatively. METHODS: Twenty HD and 20 PD patients as well as 20 healthy individuals were included in this study. Plasma advanced oxidation protein products, myeloperoxidase, thiol group and 3-nitrotyrosine (3-NT) levels were measured in all subjects. RESULTS: Plasma advanced oxidation protein products and myeloperoxidase levels were elevated by HD and PD treatments when compared to the control group. Conversely, plasma thiol group levels were decreased in HD and PD patients. 3-NT levels were increased by HD treatment only. CONCLUSIONS: The elevated plasma 3-NT levels in pre-HD and post-HD patients suggest that those patients have a considerably increased risk for nitrosative tissue injury. However, similar 3-NT levels of the control and PD groups support the advantage of PD therapy in terms of nitrosative tissue injury.

Synthesis and screening of cyclooxygenase inhibitory activity of some 1,3-dioxoisoindoline derivatives.

In this study, 15 compounds bearing N,N-phthaloylacetamide structure designed by the molecular simplification approach based on thalidomide structure were synthesized and evaluated for inhibitory potencies against cyclooxgenase (COX) isoenzymes, namely COX-1 and COX-2. The results suggested that the N,N-phthaloylacetamide structure, as a primary amide, has inhibitory activity against cyclooxygenase isoenzymes with a higher COX-1 selectivity. The conversion of the primary amide to secondary or tertiary derivatives lowered the potency but favored the COX-2 selectivity thus yielding the compounds with stronger COX-2 inhibiting activity.

Different p97/VCP complexes function in retrotranslocation step of mammalian ER-associated degradation (ERAD).

Studies in yeast indicate that three specialized endoplasmic reticulum-associated degradation (ERAD) pathways, namely ERAD-L, -M, or -C, dispose substrates with structural lesions in the lumenal, transmembrane, or cytosolic domains, respectively. The ubiquitin ligase (E3) Hrd1p and its cooperating partners are required for ERAD-L and -M pathways, whereas Doa10p complex is required for the ERAD-C pathway. We investigated these pathways in mammalian cells by assessing the requirements of the mammalian ERAD E3s, gp78 and Hrd1, in degradation of four substrates each with different type of structural lesions: CD3δ, Z-variant α1-antitrypsin, tyrosinase (C89R) and mutant cystic fibrosis transmembrane conductance regulator (CFTRΔF508). We demonstrated that tyrosinase (C89R) is a substrate for Hrd1 while all others are gp78 substrates. Knockdown of Hrd1 diminished gp78 substrate levels, but silencing of gp78 had no effect on Hrd1's substrate, suggesting that the functional interaction between Hrd1 and gp78 is unidirectional. Furthermore, while Ufd1 is dispensable for gp78-mediated ERAD, it is essential for Hrd1-mediated ERAD. Interestingly, Npl4 was found to be a key component for both pathways. These results suggest that the Hrd1-mediated ERAD requires a well-established retrotranslocation machinery, the p97/VCP-Ufd1-Npl4 complex, whereas the gp78 pathway needs only p97/VCP and Npl4. In addition, the three distinct ERAD pathways described in yeast may not be strictly conserved in mammalian cells as gp78 can function on three substrates with different structural lesions.

Antioxidant activity of Vitex agnus-castus L. extracts.

The ethanol, n-hexane and water extracts of Vitex agnus-castus L. leaves and fruits were screened for antioxidant activity. The antioxidant activity of plant extracts was determined by an improved assay based on the decolorization of the radical monocation of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS.+). The water and ethanol extracts showed stronger antioxidant activity than the n-hexane extracts.

The effect of acetaminophen on oxidative modification of low-density lipoproteins in hypercholesterolemic rabbits.

Oxidative modification of low-density lipoproteins (LDL) contributes to the pathology of atherosclerosis. Antioxidants may protect LDL against oxidative modification. Acetaminophen, a widely used analgesic and antipyretic agent, has significant antioxidant properties. However, there is little evidence to suggest that acetaminophen acts as an antioxidant for LDL oxidation in vivo. In this study, we investigated the in vivo effect of acetaminophen on LDL oxidation in hypercholesterolemic rabbits. The oxidative modification of LDL was identified by conjugated dienes and thiobarbituric acid-reactive substances (TBARS). In the cholesterol group which rabbits were fed a diet contained 1% g cholesterol for 8 weeks, TBARS contents and conjugated diene levels in the plasma and isolated LDL samples significantly increased compared with the control rabbits (p<0.05). However, in the cholesterol + acetaminophen group, the TBARS contents and conjugated diene levels were significantly lower than that of the cholesterol group (p<0.05). The results from in vitro studies also demonstrated that the LDL isolated from serum was oxidized by Cu(++) ions and this oxidation reduced in the presence of acetaminophen. The reduced oxidative modification of LDL by acetaminophen may be of therapeutic value in preventing the development and progression of atherosclerosis.

Synthesis of some 2(3H)-benzoxazolone derivatives and their in-vitro effects on human leukocyte myeloperoxidase activity.

Myeloperoxidase (MPO), a heme protein expressed by polymorphonuclear leukocytes, generates potent oxidants which are proposed to contribute to tissue damage during inflammation and certain pathogenesis such as neurodegenerative disorders. In this study, twenty omega-[2-oxo-3H-benzoxazol-3-yl]-N-phenylacetamide and propionamide derivatives having substituents of different lipophilic and electronic nature on the N-phenyl ring were synthesized to evaluate the inhibitory effects on in vitro leukocyte MPO chlorinating activity. The most active compounds in the series were the derivatives bearing 2-methyl and 4-nitro substituent on the N-phenyl ring.

The in vitro effects of Hypericum species on human leukocyte myeloperoxidase activity.

Myeloperoxidase (MPO) is a major component of the antimicrobial system of polymorphonuclear neutrophils. The heme enzyme MPO catalyzes the conversion of hydrogen peroxide and chloride to hypochlorous acid. Hypochlorous acid is the major strong oxidant produced by neutrophils and may contribute to inflammatory tissue damage. It was reported that certain antiinflammatory drugs are capable of inhibiting MPO activity and this inhibition may account for their antiinflammatory effect. Hypericum L. is a genus of about 400 species, widespread throughout the world. Some species of genus exhibit a significant antiinflammatory activity beside their several pharmacological properties such as antidepressant, diuretic, antihelmintic, and antibacterial. In this study, we investigated the in vitro effects of three Hypericum species, which exhibit antiinflammatory activity, on human polymorphonuclear leukocyte MPO activity. We found that each extract of Hypericum species reduced the peroxidative and chlorinating activity of human leukocyte MPO in concentration-dependent manner. The antiinflammatory activity of these species may be related with inhibition of MPO activity.

Serum biotinidase activity in children with chronic liver disease and its clinical significance.

BACKGROUND: Biotinidase is the enzyme responsible for liberating the vitamin biotin from biocytin and dietary protein-bound vitamin. Individuals lacking biotinidase activity become biotin deficient. Because the liver is the major source of plasma biotinidase, chronic liver diseases can lead to decreased serum biotinidase activity and biotin deficiency. The aim of this study is to determine serum biotinidase activity values in children with chronic liver disease and to investigate the relation among enzyme activity, certain liver function tests, and degree of liver damage. METHOD: In this study, using a spectrophotometric method, biotinidase activity was determined in sera from 62 children with chronic liver diseases (median age, 9.73 years; range, 8 months to 18 years) and from 27 healthy controls. Diagnoses of the patient group were as follows: noncirrhotic chronic hepatitis B virus infection (n = 12), metabolic liver diseases (n = 16), autoimmune hepatitis (n = 6), intrahepatic and extrahepatic cholestasis (n = 14), fulminant hepatitis (n = 5), cryptogenic cirrhosis n = 5), prehepatic portal hypertension (n = 4). Meanwhile, serum albumin, total bilirubin, alkaline phosphatase, alanine aminotransferase, and gamma-glutamyltransferase concentrations and prothrombine time were determined for each patient and the results were correlated with serum biotinidase activity. RESULTS: There was significant difference between mean enzyme activity of the controls (7.6 +/- 1.2 nmol x min(-1) x mL(-1)) and of all patients with chronic liver disease (6.3 +/- 2.5 nmol x min(-1) x mL(-1)) ( P < 0.05). Serum biotinidase activity in patients with noncirrhotic chronic liver diseases (chronic viral hepatitis, prehepatic portal hypertension, glycogen storage disease, Gaucher disease) was within the normal ranges. However, serum biotinidase activity in patients with cirrhosis and Wilson disease was significantly less than that of the control group ( P < 0.05). The lowest enzyme activities were detected in patients with fulminant hepatitis. CONCLUSION: In this study, serum biotinidase activity was significantly lower in patients with cirrhosis, particularly in the patients with decompensated cirrhosis and fulminant hepatitis who exhibited no clinical symptoms related to biotin deficiency. The decreased serum biotinidase activity in chronic liver diseases was associated with severe impairment of hepatocellular function.