| 1 | Domain-domain associations in cystic fibrosis transmembrane
conductance regulator.
Wang W, He Z, O'Shaughnessy TJ, Rux J, Reenstra WW. Alfred I. duPont Hospital for Children, Wilmington, Delaware 19803. Cystic fibrosis is caused by mutations in the cystic fibrosis
transmembrane conductance regulator (CFTR) gene. CFTR is a chloride
channel whose activity requires protein kinase A-dependent phosphorylation
of an intracellular regulatory domain (R-domain) and ATP hydrolysis at the
nucleotide-binding domains (NBDs). To identify potential sites of
domain-domain interaction within CFTR, we expressed, purified, and
refolded histidine (His)- and glutathione-S-transferase (GST)-tagged
cytoplasmic domains of CFTR. ATP-binding to his-NBD1 and his-NBD2 was
demonstrated by measuring tryptophan fluorescence quenching. Tryptic
digestion of in vitro phosphorylated his-NBD1-R and in situ phosphorylated
CFTR generated the same phosphopeptides. An interaction between NBD1-R and
NBD2 was assayed by tryptophan fluorescence quenching. Binding among all
pairwise combinations of R-domain, NBD1, and NBD2 was demonstrated with an
overlay assay. To identify specific sites of interaction between domains
of CFTR, an overlay assay was used to probe an overlapping peptide library
spanning all intracellular regions of CFTR with his-NBD1, his-NBD2, and
GST-R-domain. By mapping peptides from NBD1 and NBD2 that bound to other
intracellular domains onto crystal structures for HisP, MalK, and Rad50,
probable sites of interaction between NBD1 and NBD2 were identified. Our
data support a model where NBDs form dimers with the ATP-binding sites at
the domain-domain interface. | |
|
| ||
| 2 | Captopril inhibits the pulmonary toxicity of paraquat in rats.
Candan F, Alagozlu H. Department of Chemistry, Faculty of Science and Art, Cumhuriyet University, Sivas, Turkey. Paraquat (PQ) is a herbicide that is very toxic to all living
organisms. It generates free radicals and leads to acute or chronic lung
injury. Free radicals are often associated with fibrogenesis, which occurs
in various disease states. The purpose of this study was to determine
whether captopril prevents paraquat toxicity in lung tissue. Paraquat
alone increased the level of lipid peroxidation (LPO) and the activity of
superoxide dismutase (SOD) after 4, 12, 24 and 72 h of administration.
Also, the level of hydroxyproline showed an increase after 24 h of
paraquat administration. However, paraquat also decreased the level of
glutathione (GSH) and the activity of glutathione peroxidase (GSH-Px).
Captopril (50 mg/kg i.p.) and paraquat were simultaneously injected (40
mg/kg i.p.), and the captopril injection 1 h after paraquat ameliorated
the biochemical toxicity induced by paraquat. This was evidenced by a
significant reduction in LPO and balancing the endogenous antioxidant
capacity by normalizing the activities of SOD and GSH-Px and the GSH
content in the lung tissue. Moreover, captopril injection prevented the
increase of hydroxyproline content as an index of lung fibrosis. From
these results, the beneficial effects of captopril on paraquat toxicity
appear to be through enhancement of the endogenous antioxidant system
preventing the lung fibrosis. | |
|
| ||
| 3 | Increased plasma fatty acid concentrations after respiratory
exacerbations are associated with elevated oxidative stress in cystic
fibrosis patients.
Wood LG, Fitzgerald DA, Gibson PG, Cooper DM, Garg ML. Discipline of Nutrition and Dietetics, the University of Newcastle, New South Wales, Australia (LGW and MLG). BACKGROUND: Oxidative stress and depleted antioxidant defenses occur in
stable cystic fibrosis patients. During acute infection, the balance
between oxidants and antioxidants may be further disturbed. OBJECTIVE: We
examined the oxidative stress during acute infection in cystic fibrosis
patients by measuring 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha))
and antioxidant defenses in relation to dietary intake, fatty acid status,
immune function, and clinical status. DESIGN: Plasma concentrations of
total 8-iso-PGF(2alpha), vitamins E and C, beta-carotene, zinc, selenium,
and copper; plasma fatty acid compositions; erythrocyte glutathione
concentrations; glutathione peroxidase and superoxide dismutase activity;
sputum glutathione and 8-iso-PGF(2alpha) concentrations; lung function;
clinical symptoms; and dietary intake were measured in 15 cystic fibrosis
patients before and after 10-14 d of intravenous antibiotic treatment for
a pulmonary exacerbation. RESULTS: After treatment, respiratory status
improved (percentage of forced expiratory volume in 1 s: 60 +/- 6% at
baseline compared with 74 +/- 7% after treatment, P = 0.01), quality of
well-being improved (P = 0.001), and total plasma 8-iso-PGF(2alpha)
concentrations increased from 469 nmol/L at baseline (interquartile range:
373-554 nmol/L) to 565 nmol/L after treatment (interquartile range:
429-689 nmol/L; P = 0.008). Total energy, fat, carbohydrate, and protein
intakes per kilogram body weight also increased; however, dietary
antioxidant intake was unchanged. Plasma fatty acid concentrations
increased after treatment, strongly correlating with plasma
8-iso-PGF(2alpha) concentrations (r = 0.768, P = 0.001). There were no
significant changes in white cell counts or plasma concentrations of
vitamins E and C or beta-carotene. Erythrocyte glutathione peroxidase
activity was reduced after treatment, whereas there was no significant
change in superoxide dismutase activity. CONCLUSIONS: Oxidative stress
increased after treatment for pulmonary exacerbations and was strongly
linked to increased concentrations of plasma fatty acids. Although
intravenous antibiotic therapy and physiotherapy improved lung function
within 10-14 d of treatment, the biochemical effects of oxidation
continued further. Thus, antioxidant intervention during treatment for and
recovery from acute infection in cystic fibrosis should be considered.
| |
|
| ||
| 4 | Riboflavin deficiency in cystic fibrosis: three case reports.
McCabe H. Newcastle Nutrition, Royal Victoria Infirmary, Newcastle Upon Tyne Hospitals NHS Trust, Newcastle Upon Tyne NE1 4LP, UK. nutrition@trvi.nuth.northy.nhs.uk Three cases of clinical riboflavin deficiency are reported in children aged 2-10 years attending a regional Cystic Fibrosis clinic. Riboflavin deficiency presented as angular stomatitis in all three patients. Patients were confirmed to be riboflavin deficient by assaying the activity of erythrocyte glutathione reductase. Patients were not on routine supplements of water-soluble vitamins before presentation and were treated with riboflavin supplements as part of a water-soluble vitamin complex. At presentation, one patient had poor nutritional status, but two patients were adequately nourished, receiving overnight Gastrostomy feeds. Data on these two patients indicate an adequate dietary intake of riboflavin, suggesting a mechanism for increased requirements, inadequate absorption or utilization. Additional deficiencies of thiamin, pyridoxine and iron were also observed. This paper reports the occurrence of a vitamin deficiency not previously reported in the cystic fibrosis population. MeSH Terms:
From PubMed | |
|
| ||
| 5 | Effects of salviainolic acid A (SA-A) on liver injury: SA-A action
on hepatic peroxidation.
Liu P, Hu Y, Liu C, Liu C, Zhu D. Institute of Liver Diseases, Shanghai University of Traditional Chinese Medicine, and Shanghai Institute of Meteria Medica, Chinese Academy of Science. Shanghai, P. R. China. Background/Aims: This study aimed to investigate the actions of
salviainolic acid A (SA-A), an antiperoxidative component of Salvia
miltiorrhiza (Sm), on rat liver injury and fibrosis. Methods: Acute and
chronic rat liver injury models were established using carbon
tetrachloride (CCl4). After 48 h (acute) or during 6 weeks of CCl4
injection, rats were further divided and treated with biphenyl
dimethyl-dicarboxylate (BDD) or colchicine, as a control antifibrotic
treatment, with Sm, a herbal compound, or SA-A, a water-soluble extract of
Sm. Liver function was investigated by assessing alanine transaminase
(ALT) and aspartate transaminase (AST) activities, histological analysis,
hydroxyproline (Hyp) and malondiadehyde (MDA) content. In vitro, isolated
cultured hepatocytes were injured with CCl4 gas for 24 h, followed by
treatment with either vitamin E or various concentrations of SA-A. The
extent of hepatocyte injury was monitored by analyzing various lipid
peroxidative parameters such as superoxide dismutase (SOD), glutathione
(GSH), catalase (CAT), lactase dehydrogenase (LDH), and glutathione
peroxidase (GSH-PX) levels in hepatocyte supernatants. Results: SA-A
significantly decreased abnormal serum ALT activity both in acutely and
chronically injured rat livers, decreased abnormal serum AST activity, Hyp
and MDA content and attenuated hepatic collagen deposition. After CCl4
incubation and injury, the activities of AST, ALT CAT, GSH-PX and LDH and
MDA content in hepatocyte supernatants increased significantly, but GSH
levels decreased significantly. SA-A markedly improved these pathological
changes in a dose-dependent manner. 10-4 mol/l SA-A had stronger
inhibitory action than vitamin E. Conclusions: Our studies suggest that
SA-A has antiperoxidative effects on injured hepatocytes in liver injury
and fibrosis induced by CCl4. | |
|
| ||
| 6 | Anti-oxidant ebselen causes the resolution of experimentally
induced hepatic fibrosis in rats.
Wasser S, Lim GY, Ong CN, Tan CE. Department of Pediatric Surgery, KK Women's and Children's Hospital and Department of Community, Occupational and Family Medicine, National University of Singapore, Singapore. BACKGROUND: Hepatic fibrosis occurs because of injury to the liver
parenchyma and biliary system. We have investigated the effect of an
organic selenium anti-oxidant, ebselen, in the resolution of
experimentally induced hepatic fibrosis, and evaluated its effect on
various paradigms involved in hepatic fibrosis. METHODS: Following
pretreatment with phenobarbitone, liver fibrosis was induced in male
Fischer 344 rats by using carbon tetrachloride treatment for 10 weeks.
Carbon tetrachloride-treated rats were randomly assigned into two groups:
(i) no ebselen; and (ii) ebselen administered for 3 weeks following a
10-week carbon tetrachloride treatment period. Normal controls were: (i)
neither carbon tetrachloride nor ebselen treated; or (ii) ebselen treated
for 13 weeks. Liver sections were stained with hematoxylin and eosin,
Masson trichrome and stained for reticulin by using silver impregnation.
Reverse transcription-polymerase chain reaction was used to analyze the
steady-state levels of gene(s) involved in: (i) hepatic fibrosis, namely,
transforming growth factor-beta1, procollagen I and III, tissue inhibitor
of metalloproteinase-1 and matrix metalloproteinase-13; (ii) oxidative
stress, namely, cytochrome P4502E1; and (iii) preneoplastic liver foci,
namely, the placental form of glutathione-S-transferase. RESULTS:
Histological staining showed that ebselen resolves carbon
tetrachloride-induced hepatic fibrosis. Treatment with ebselen reduced
steady-state levels of transforming growth factor-beta1, procollagen I and
III, tissue inhibitor of metalloproteinase-1, cytochrome P4502E1 and
placental form glutathione-S-transferase transcripts, and increased
transcripts of matrix metalloproteinase-13. CONCLUSION: These findings
provide evidence that ebselen significantly causes the resolution of
carbon tetrachloride-induced hepatic fibrosis in rats. | |
|
| ||
| 7 | Increased expression of cyclooxygenase-2 protein during rat
hepatocarcinogenesis caused by a choline-deficient, L-amino acid-defined
diet and chemopreventive efficacy of a specific inhibitor, nimesulide.
Denda A, Kitayama W, Murata A, Kishida H, Sasaki Y, Kusuoka O,
Tsujiuchi T, Tsutsumi M, Nakae D, Takagi H, Konishi Y.
Department of Oncological Pathology, Cancer Center, Nara Medical Univesity, 840 Shijo-cho, Kashihara, Nara 634-8521, Japan. adenda@nmu-gw.cc.naramed-u.ac.jp Expression of cyclooxygenase (COX)-2 protein during rat hepatocarcinogenesis associated with fatty change, fibrosis, cirrhosis and oxidative DNA damage, caused by a choline-deficient, L-amino acid-defined (CDAA) diet were investigated in F344 male rats, along with the chemopreventive efficacy of the specific COX-2 inhibitor, nimesulide (NIM). Nimesulide, which was administered in the diet at concentrations of 200, 400, 600 and 800 p.p.m. for 12 weeks, decreased the number and size of preneoplastic enzyme-altered liver foci, levels of oxidative DNA damage, and the grade and incidence of fibrosis in a dose-dependent manner. A preliminary long-term study of 65 weeks also revealed that 800 p.p.m. NIM decreased the multiplicity of neoplastic nodules and hepatocellular carcinomas and prevented the development of cirrhosis. Western blot analysis revealed that COX-2 protein was barely expressed in control livers and increased approximately 2.9-fold in the livers of rats fed on a CDAA diet for 12 weeks and approximately 4.5-5.4-fold in tumors, with a diameter larger than 5 mm, at 80 weeks. Immunohistochemically, COX-2 protein was positive in sinusoidal and stromal cells in fibrotic septa, which were identified by immunoelectron microscopy as Kupffer cells, macrophages, either activated Ito cells or fibroblasts, after exposure to the CDAA diet for 12 weeks, whereas it was only occasionally weakly positive in sinusoidal, probably Kupffer, cells in control livers. In neoplastic nodules in rats fed on a CDAA diet for 30 and 80 weeks, sinusoidal cells and cells with relatively large round nuclei and scanty cytoplasm were strongly positive for COX-2 protein, with the neoplastic hepatocytes in the minority of the nodules, but not the cancer cells, being moderately positive. These results clearly indicate that rat hepatocarcinogenesis, along with fatty change, fibrosis and cirrhosis, is associated with increased expression of COX-2 protein, and point to the chemopreventive efficacy of a selective COX-2 inhibitor against, at least, the early stages of hepatocarcinogenesis. MeSH Terms:
From PubMed | |
|
| ||
| 8 | The effect of melatonin on bleomycin-induced pulmonary fibrosis in
rats.
Arslan SO, Zerin M, Vural H, Coskun A. Department of Pharmacology, Faculty of Medicine, Zonguldak Karaelmas University, Zonguldak, Turkey. soarslan@lycos.com The present investigation was designed to determine the protective
effects of melatonin against bleomycin (BLM)-induced oxidant lung
toxicity. Wistar-albino rats were divided into four groups: saline (SA,
0.4 mL/animal), 1% ethanol-saline (ALC, 0.4 mL/animal), bleomycin sulphate
(BLM, 10 mg/kg), or bleomycin sulphate + melatonin (BLM, 10 mg/kg + MLT,
10 mg/kg). All injections were given intraperitoneally (i.p.), twice
weekly for a period of 3 wk (a total of seven injections for each group).
Twenty-five days after BLM treatment, pulmonary fibrosis was assessed as
hydroxyproline content in lung homogenates. Findings show that BLM-induced
pulmonary injury resulted in increases in bronchoalveolar lavage fluid
(BALF) biomarkers including total protein, lactate dehydrogenase (LDH),
glutathione-peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase
(CAT). Additionally, the levels of thiobarbituric acid reactive substances
(TBARS), an index of lipid peroxidation (LPO), were also increased in
BALF. Conversely, the level of glutathione (GSH) was reduced in BALF of
BLM-treated rats. Melatonin provided protection against BLM-induced
pulmonary fibrosis by suppressing oxidative stress. It abolished
BLM-stimulated LPO and reversed the imbalance between oxidants and
antioxidants in the BALFs. Results thus indicate that melatonin inhibits
BLM-induced lung toxicity associated with oxidative damage. | |
|
| ||
| 9 | Changes in (Na + K)-adenosine triphosphatase activity and
ultrastructure of lung and kidney associated with oxidative stress induced
by acute ethanol intoxication.
Rodrigo R, Trujillo S, Bosco C, Orellana M, Thielemann L, Araya J.
Instituto de Ciencias Biomédicas, Programa de FarmacologÃa Molecular y ClÃnica, Facultad de Medicina, Universidad de Chile, Santiago, Chile. rrogrigo@machi.med.uchile.cl STUDY AND OBJECTIVES: (Na + K)-adenosine triphosphatase (ATPase) activity, oxidative stress parameters, and morphologic characteristics of the lung and kidney of rats under acute ethanol intoxication were assessed to investigate the pathogenic mechanism of tissue damage. DESIGN AND INTERVENTIONS: Adult rats were given ethanol (5.5 g/kg) 3 h before performing the biochemical and morphologic studies. Oxidative stress was assessed by measuring the levels of reduced glutathione (GSH) and glutathione disulfide (GSSG), the activities of key antioxidant enzymes (ie, catalase [CAT], superoxide dismutase [SOD], and glutathione peroxidase [GSH-Px]) and malondialdehyde production. (Na + K)-ATPase, a membrane-bound enzyme, also was assayed. RESULTS: In the lung, ethanol increased MDA production by 60%, decreased GSH levels by 33%, decreased SOD and GSH-Px activity by 10%, and decreased (Na + K)-ATPase activity by 55%, whereas CAT activity was unaltered. Impaired surfactant secretion and cell adhesion of lung epithelial cells were found. In the kidney, ethanol did not influence the activity of (Na + K)-ATPase or lipid peroxidation, despite the reduction of both GSH and the GSH/GSSG ratio. Focally thickened glomerular basement membrane, apoptosis of foot processes, and tubulointerstitial fibrosis were found. CONCLUSIONS: These data suggest that oxidative stress plays a role in mediating the ethanol-induced down-regulation of lung (Na + K)-ATPase. GSH depletion seems to be a major determinant of this effect. Independent mechanisms seem to account for the morphologic alterations of these organs. MeSH Terms:
From PubMed | |
|
| ||
| 10 | Immunohistochemical study of hepatic oval cells in human chronic
viral hepatitis.
Ma X, Qiu DK, Peng YS. Shanghai Institute of Digestive Diseases, Renji Hospital, 145 Shandong Zhong Road, Shanghai 200001, China. xiongma@netease.com AIM: To detect immunohistochemically the presence of oval cells in chronic viral hepatitis with antibody against c-kit. METHODS: We detected oval cells in paraffin embedded liver sections of 3 normal controls and 26 liver samples from patients with chronic viral hepatitis, using immunohistochemistry with antibodies against c-kit, piclass glutathione S-transferase (pi-GST) and cytokeratins 19 (CK19). RESULTS: Oval cells were not observed in normal livers. In chronic viral hepatitis, hepatic oval cells were located predominantly in the periportal region and fibrosis septa,characterized by an ovoid nucleus, small size,and scant cytoplasm. Antibody against stem cell factor receptor, c-kit, had higher sensitivity and specificity than pi-GST and CK19. About 50%-70% of c-kit positive oval cells were stained positively for either pi-GST or CK19. CONCLUSION: Oval cells are frequently detected in human livers with chronic viral hepatitis, suggesting that oval cell proliferation is associated with the liver regeneration in this condition. MeSH Terms:
From PubMed | |
|
| ||
| 11 | Tumor necrosis factor soluble receptor p55 and lipid peroxidation
in patients with acute alcoholic hepatitis.
Naveau S, Abella A, Raynard B, Balian A, Giraud V, Montembault S,
Mathurin P, Keros LG, Portier A, Capron F, Emilie D, Galanaud P, Chaput
JC. Service d'Hépato-Gastroentérologie, Hĵpital Antoine Béclère, Clamart, France. OBJECTIVES: In experimental models, liver injury induced by ethanol, cytotoxic activity of tumor necrosis factor (TNF) -alpha is principally mediated by TNF receptor p55 (TNFRp55). Among the various mechanisms underlying the toxic effects of TNF-alpha, overproduction of reactive oxygen species seems to play a key role in mediating TNF-alpha-induced cytotoxicity. The aim of this study was to evaluate, in patients with alcoholic liver disease, whether alcohol TNFRp55-mediated hepatotoxicity could account for lipid peroxidation expressed by significant increase in serum thiobarbituric reactive acid substances (TBARS) content, and could be amplified by decrease in blood total glutathione content and decrease in plasma antioxidant protective capacity. METHODS: We studied 27 patients with histological alcoholic liver disease (five fibrosis, six acute alcoholic hepatitis (AAH) without cirrhosis, four cirrhosis without AAH, and 12 cirrhosis with AAH. TNFsRp55 and TNFsRp75 plasma levels were measured using ELISA assays. Plasma lipid peroxidation was evaluated by the content of TBARS. Total glutathione (tGSH) content in blood was determined by a kinetic assay. The sensitivity of erythrocytes to an oxidative stress and the plasma antioxidant protective capacity were simultaneously determined by a simple method. RESULTS: In the 18 patients with mild or severe AAH, the plasma levels of TNFsRp55 were negatively correlated with tGSH and were positively correlated with TBARS, with total bilirubin and with discriminant function. tGSH was positively correlated with plasma selenium. The plasma levels of TNFsRp75 were positively correlated with TBARS and with total bilirubin. There was no significant correlation with the mean inhibitory 50% plasma volume or with the percentage of hemolyzed erythrocytes. CONCLUSIONS: Our data support the notions that, in patients with AAH, TNFsRp55 probably mediates cytotoxicity of TNF-alpha, and that cytotoxic effect could be amplified by tGSH depletion in enhancing lipid peroxidation. MeSH Terms:
From PubMed | |
|
| ||
| 12 | Comparative in vitro toxicity of cadmium and lead on redox cycling
in type II pneumocytes.
Tatrai E, Kovacikova Z, Hudak A, Adamis Z, Ungvary G. Fodor József National Center for Public Health, Budapest, Hungary. tatray@elender.hu Both cadmium and lead have pulmonary toxicity: cadmium can cause lung
cancer, fibrosis and emphysema; lead can induce a moderate interstitial
pulmonary fibrosis. Both metals give rise to depletion of glutathione and
depletion of the protein-bound sulfhydryl groups, and lead to the
production of reactive oxygen species. In the primary culture of type II
pneumocytes, which is one of the most important cell groups from the
aspect of glutathione metabolism and thus redox balance, the effect of
cadmium chloride and lead nitrate upon the enzymes of the glutathione
cycle, upon superoxide dismutase and upon the structure of type II
pneumocytes was examined. Depending on the concentration, cadmium
inhibited each of these parameters, whereas lead nitrate significantly
increased the activity of glutathione reductase while inhibiting other
parameters. Both metals induced damage of the membranes of type II cells,
depending on the concentration, although cadmium caused significantly more
damage than lead. The data obtained suggest that both substances cause an
imbalance in the redox cycle and diversely affect the function and
membrane structure of type II pneumocytes. MeSH Terms:
From PubMed | |
|
| ||
| 13 | Activation of Kupffer cells during the course of carbon
tetrachloride-induced liver injury and fibrosis in rats.
Luckey SW, Petersen DR. Molecular Toxicology and Environmental Health Sciences Program, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA. Kupffer cells are involved in the pathogenesis of chemically mediated
liver injury through release of biologically active mediators that promote
the pathogenic process. The purpose of this study was to elucidate
specific biochemical and molecular changes occurring in Kupffer cells
throughout a time course of carbon tetrachloride (CCl(4))-mediated liver
injury and fibrosis. Rats were administered 1 ml/kg of CCl(4) (10% v/v
olive oil) twice weekly for up to 6 weeks. Plasma alanine aminotransferase
values and hematoxylin-and-eosin- and trichrome-stained liver sections
indicated minor liver damage at 2 weeks followed by increased damage and
collagen deposition by 4 and 6 weeks. Additionally, mRNA levels in Kupffer
cells isolated from CCl(4)-treated rats demonstrated significant increases
in tumor necrosis factor alpha (TNF alpha); tumor growth factor beta;
interleukin-6 (IL-6); interleukin 1 beta; cyclooxygenase 2; CD14, and I
kappa B alpha transcripts after 2 and 4 weeks of treatment. However, the
expression of these genes at 6 weeks was similar to that of controls.
Increased gene expression of cytokines in Kupffer cells isolated from
CCl(4)-treated rats was accompanied by increases in protein production of
TNF alpha, IL-6, IL-1 beta, and interleukin 10 following
lipopolysaccharide stimulation. Further, liver sections stained for
ED2-positive cells demonstrated an increase in the number of resident
macrophages at 2 and 4 weeks with a slight decrease in ED2-positive cells
by week 6 but still significantly more than control. Analysis of reduced
glutathione (GSH) and oxidized glutathione (GSSG) indicated that Kupffer
cells from CCl(4)-treated animals exhibited a 50% decrease in GSH at 2 and
4 weeks, whereas no significant changes were observed for GSSG. In
conclusion, these data implicate Kupffer cells as a critical mediator of
the inflammatory and fibrogenic responses during CCl(4)-mediated liver
damage and provide new insight into the temporal molecular and biochemical
changes associated with the ability of these resident macrophages to
modulate liver injury. MeSH Terms:
From PubMed | |
|
| ||
| 14 | Antibodies against the carboxyl-terminal end of the Trypanosoma
cruzi ribosomal P proteins are pathogenic.
Lopez Bergami P, Scaglione J, Levin MJ. Laboratorio de Biologia Molecular de la Enfermedad de Chagas, Instituto de Investigaciones en IngenierÃa Genética y BiologÃa Molecular (INGEBI), 1428, Buenos Aires, Argentina. Sera from patients with chronic Chagas heart disease recognize the carboxyl-terminal regions of the Trypanosoma cruzi ribosomal P proteins defined by B cell epitopes P013 (EDDDDDFGMGALF) and R13 (EEEDDDMGFGLFD) corresponding to the T. cruzi ribosomal P0 (TcP0) and P2beta (TcP2beta) proteins, respectively. It has been hypothesized that both epitopes may induce antibodies that cross-react and stimulate the beta1-adrenoreceptor. However, no proof as to their pathogenicity has been obtained. We investigated the consequences of immunizing mice with either TcP0 or TcP2beta proteins. Of 24 immunized animals, 16 generated antibodies against the carboxyl-terminal end of the corresponding protein, 13 of which showed an altered ECG (P<0.001, 81%). Immunization with TcP0 induced anti-P013 antibodies that bind to and stimulate cardiac G-protein-coupled receptors and are linked to the induction of supraventricular arrhythmia, repolarization, and conduction abnormalities as monitored by serial electrocardiographic analysis. In contrast, immunization with TcP2beta generated anti-R13 antibodies with an exclusive beta1-adrenergic-stimulating activity whose appearance strictly correlated with the recording of supraventricular tachycardia and death. These findings demonstrate that anti-P antibodies are arrhythmogenic in the setting of a normal heart, since no inflammatory lesions or fibrosis were evident to light microscopic examination. MeSH Terms:
From PubMed | |
|
| ||
| 15 | Enalapril attenuates oxidative stress in diabetic rats.
de Cavanagh EM, Inserra F, Toblli J, Stella I, Fraga CG, Ferder L.
Massone Institute, Institute of Cardiovascular Research, Buenos Aires, Argentina. Oxidative stress is involved in both the pathogenesis and complications of diabetes. ACE inhibitors can slow the progression of cardiac and renal impairments related to diabetes. The effect of enalapril treatment on oxidative stress and tissue injury was studied in hearts, kidneys, and livers from streptozotocin-induced diabetic rats. Twenty-four rats were divided into the following groups: streptozotocin (65 mg/kg, single intraperitoneal dose), streptozotocin+enalapril (20 mg enalapril/L drinking water), and control (intraperitoneal saline). Seven months after streptozotocin injection, organs were studied by light microscopy and collagen III immunolabeling. Tissue lesions and collagen labeling were graded by a semiquantitative score (0 to 4). Total glutathione content, glutathione redox status (reduced/oxidized glutathione), antioxidant enzyme activities, protein-associated sulfhydryls, thiobarbituric acid-reactive substances, and fluorescent chromolipids were determined in tissue homogenates. Glycemia was higher in both the streptozotocin and streptozotocin+enalapril groups relative to the control group. In the streptozotocin group, creatinine clearance and body weight were lower, and systolic blood pressure and urinary albumin excretion were higher than in the streptozotocin+enalapril and control groups. Heart, kidney, and liver lesion/labeling scores were significantly higher in the streptozotocin group compared with the streptozotocin+enalapril and control groups. Kidney and liver total glutathione was lower in the streptozotocin group relative to the control group (P<0.05). Enalapril treatment significantly attenuated the reduction of total glutathione. In the heart, kidney, and liver, both glutathione and proteins were relatively more oxidized in the streptozotocin group relative to the control group (P<0.05). Protein and glutathione oxidation were attenuated in the streptozotocin+enalapril group in the 3 tissues studied (P<0.05). Enalapril treatment attenuated the oxidation of lipids in the heart and kidney (P<0.05). Tissue fibrosis scores were inversely correlated with (1) both total glutathione and reduced/oxidized glutathione in heart, kidney, and liver and (2) glutathione reductase activity in the kidney. These results suggest that in streptozotocin-induced diabetic rats, the protective action of enalapril might be mediated, at least in part, by its effect on tissue oxidant/antioxidant status. MeSH Terms:
From PubMed | |
|
| ||
| 16 | Liver iron accumulation in chronic hepatitis C patients without HFE
mutations: relationships with histological damage, viral load and genotype
and alpha-glutathione S-transferase levels.
Giannini E, Mastracci L, Botta F, Romagnoli P, Fasoli A, Risso D,
Faravelli F, Ceppa P, Lantieri PB, Icardi GC, Testa R. Gastroenterology Unit, Department of Internal Medicine, University of Genoa, Italy. BACKGROUND: Host and viral factors have been suggested as possible causative factors for the presence of liver iron accumulation in chronic hepatitis C. However, there is no agreement regarding the influence of liver iron accumulation on the biochemical and histological severity of chronic hepatitis C. Moreover, data concerning the relationships between both viral load and genotype and liver iron accumulation are scanty. AIMS: To evaluate the biochemical, histological and virological assessment of a group of chronic hepatitis C patients without risk factors for iron overload, on the basis of the presence, degree and distribution of liver iron accumulation. METHODS: Fifty-three chronic hepatitis C patients (34 men, 19 women; age 44 +/- 11 years) with no risk factors for liver iron accumulation and showing no HFE mutations were chosen from a broader cohort of chronic hepatitis C patients. The presence, degree and distribution of liver iron accumulation were assessed using Deugnier's score. Relationships between the presence of liver iron accumulation and grading and staging were carried out separately. Hepatitis C virus RNA serum levels and viral genotype were compared in patients with or without liver iron accumulation. Alpha glutathione S-transferase serum levels were assessed in all patients. RESULTS: Overall, liver iron accumulation was mild and was present in 19 patients (36%). It was associated with male gender (P = 0.0358), and was reflected by high serum iron levels (P = 0.001) and high ferritin levels (P < 0.0001). Hepatitis C virus RNA levels and genotype were not associated with the presence of liver iron accumulation. In multivariate analysis, ferritin was the only variable significantly associated with liver iron accumulation (P < 0.0001). Grading was higher in patients with liver iron accumulation regardless of the site of iron deposition. Fibrosis was present in all patients with iron overload; these patients were more frequently cirrhotic. Moreover, patients with mesenchymal or mixed deposition had higher staging than patients with hepatocytic or no iron deposition. This feature was reflected by higher alpha-glutathione S-transferase levels. CONCLUSIONS: Liver iron accumulation is mild in chronic hepatitis C patients without HFE mutations and is mainly reflected by serum ferritin levels. Viral characteristics do not seem to play a role in iron deposition. Liver iron accumulation is associated with higher grading, advanced fibrosis and cirrhosis. Moreover, higher staging is associated with mesenchymal or mixed iron deposition. In these patients, higher alpha-glutathione S-transferase levels seem to reflect more complex damage. MeSH Terms:
From PubMed | |
|
| ||
| 17 | Prevention of hepatic cirrhosis in rats by hydroxyl radical
scavengers.
Bruck R, Shirin H, Aeed H, Matas Z, Hochman A, Pines M, Avni Y.
Department of Gastroenterology, The E. Wolfson Medical Center, Holon, Israel. rbruck@wolfson.health.gov.il BACKGROUND/AIMS: Reactive oxygen species and oxidative stress were implicated in hepatic stellate cell activation and liver fibrosis. The aim of the present study was to examine whether the administration of free radical scavengers in vivo would prevent experimentally-induced hepatic cirrhosis in rats. METHODS: Cirrhosis was induced by administration of thioacetamide (TAA; 200 mg/kg, i.p.) twice/week, for 12 weeks. Rats were treated concurrently with either dimethylsulfoxide (DMSO; 4 g/kg, s.c. or p.o.) or dimethylthiourea (DMTU; 200 mg/kg i.p.) three times a week. RESULTS: Liver fibrosis (histopathological score, spleen weight, and hepatic hydroxyproline) was abolished in rats treated with TAA and either DMSO or DMTU (P < 0.001). Accordingly, the hepatic expression of alpha smooth muscle actin, tissue inhibitor of metalloproteinase 2 and collagen alpha1 (I) gene were inhibited. The hepatic level of methane-sulfinic acid (produced by the interaction of DMSO with hydroxyl radicals) was increased in rats treated with TAA + DMSO (P = 0.0005) and decreased after pretreatment of these rats with DMTU (P = 0.008). However, the hepatic levels of malondialdehyde, lipid peroxides and protein carbonyls were not lower in the DMSO- and DMTU-treated groups. CONCLUSIONS: The administration of free radical scavengers prevented the development of TAA-induced liver cirrhosis probably associated with decreased oxidative stress. MeSH Terms:
From PubMed | |
|
| ||
| 18 | Arsenic and liver disease.
Guha Mazumder DN. Department of Medicine and Gastroenterology, Institute of Postgraduate Medical Education and Research, Calcutta. The hepatotoxic action of arsenic, when used as a therapeutic agent, has long been recognised. Data on liver involvement following chronic exposure to arsenic-contaminated water are scanty. The nature and degree of liver involvement are reported on the basis of hospital based studies in patients who consumed arsenic contaminated drinking water for one to 15 years. Two hundred forty-eight patients with evidence of chronic arsenic toxicity underwent clinical and laboratory examination including liver function tests and hepatitis B surface antigen (HBsAg) status. Liver biopsy was done in 69 cases; in 29 patients, liver arsenic content was estimated by neutron activation analysis. Hepatomegaly was present in 190 of 248 patients (76.6%). Non-cirrhotic portal fibrosis was the predominant lesion (91.3%) in liver histology. The maximum arsenic content in liver was 6 mg/kg (mean 1.46 [0.42], control value 0.16 [0.04]; p <0.001); it was undetected in 6 of 29 samples studied. The largest number of patients with liver disease due to chronic arsenicosis from drinking arsenic contaminated water are reported. Non-cirrhotic portal fibrosis is the predominant lesion in this population. Hepatic fibrosis has also been demonstrated due to long term arsenic toxicity in an animal model. Initial biochemical evidence of hepatic membrane damage, probably due to reduction of glutathione and antioxidant enzymes, may be seen by 6 months. Continued arsenic feeding resulted in fatty liver with serum aminotransferases elevated at 12 months and hepatic fibrosis at 15 months. MeSH Terms:
From PubMed | |
|
| ||
| 19 | Mitochondrial oxidative damage and myocardial fibrosis in rats
chronically intoxicated with moderate doses of ethanol.
Vendemiale G, Grattagliano I, Altomare E, Serviddio G, Portincasa P,
Prigigallo F, Palasciano G. Dipartimento di Medicina Interna e Pubblica (DIMIMP), Univerisità di Bari, Piazza G. Cesare, 11-70124, Bari, Italy. g.vendemaile@semeiotica.uniba.it Mitochondrial oxidative balance and myocardial fibrosis were investigated in pair-fed rats received ethanol (3%) or saccharose in drinking water for 8 weeks. The concentrations of glutathione, malondialdehyde, protein carbonyls and sulfhydrils were determined. The presence and distribution of fibronectin were detected by immunohistochemistry. The myocardial concentrations of reduced glutathione and protein sulfhydrils were lower in ethanol treated rats. The oxidised/reduced glutathione ratio, the levels of malondialdehyde and protein carbonyls were higher in ethanol-treated rats. The mitochondrial amount of proteins, glutathione and protein sulfhydrils were lower in ethanol treated rats, whereas the content of protein carbonyls and malondialdehyde were higher. Accumulation of fibronectin was detected at subepicardial and subendocardial districts in ethanol-treated rats, with moderate degree of fibrosis in 20% of the cases. In conclusion, moderate ethanol consumption is associated with oxidative damage to heart mitochondria and fibronectin deposition. These oxidative and ultrastuctural changes may be assumed as basic alterations in the development of alcoholic cardiomyopathy. MeSH Terms:
From PubMed | |
|
| ||
| 20 | Mu 2 binding directs the cystic fibrosis transmembrane conductance
regulator to the clathrin-mediated endocytic pathway.
Weixel KM, Bradbury NA. Cystic Fibrosis Research Center, Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA. The cystic fibrosis transmembrane conductance regulator (CFTR) contains a conserved tyrosine-based internalization motif, (1424)YDSI, which interacts with the endocytic clathrin adaptor complex, AP-2, and is required for its efficient endocytosis. Although direct interactions between several endocytic sequences and the medium chain and endocytic clathrin adaptor complexes have been shown by protein-protein interaction assays, whether all these interactions occur in vivo or are physiologically important has not always been addressed. Here we show, using both in vitro and in vivo assays, a physiologically relevant interaction between CFTR and the mu subunit of AP-2. Cross-linking experiments were performed using photoreactive peptides containing the YDSI motif and purified adaptor complexes. CFTR peptides cross-linked a 50-kDa subunit of purified AP-2 complexes, the apparent molecular mass of mu 2. Furthermore, isolated mu 2 bound to the sorting motif, YDSI, both in cross-linking experiments and glutathione S-transferase pull-down experiments, confirming that mu 2 mediates the interaction between CFTR and AP-2 complexes. Inducible overexpression of dominant-negative mu 2 in HeLa cells results in AP-2 complexes that fail to interact with CFTR. Moreover, internalization of CFTR in mutant cells is greatly reduced compared with wild type HeLa cells. These results indicate that the AP-2 endocytic complex selectively interacts with the conserved tyrosine-based internalization signal in the carboxyl terminus of CFTR, YDSI. Furthermore, this interaction is mediated by the mu 2 subunit of AP-2 and mutations in mu 2 that block its interaction with YDSI inhibit the incorporation of CFTR into the clathrin-mediated endocytic pathway. MeSH Terms:
From PubMed | |
|
| ||
| 21 | Synergistic effects of nicotine on arecoline-induced cytotoxicity
in human buccal mucosal fibroblasts.
Chang YC, Hu CC, Tseng TH, Tai KW, Lii CK, Chou MY. Department of Dentistry, Chung Shan Medical and Dental College Hospital, Taichung, Taiwan. Areca quid chewing has been linked to oral submucous fibrosis and oral cancer. Arecoline, a major areca nut alkaloid, is considered to be the most important etiologic factor in the areca nut. In order to elucidate the pathobiological effects of arecoline, cytotoxicity assays, cellular glutathione S-transferase (GST) activity and lipid peroxidation assay were employed to investigate cultured human buccal mucosal fibroblasts. To date, there is a large proportion of areca quid chewers who are also smokers. Furthermore, nicotine, the major product of cigarette smoking, was added to test how it modulated the cytotoxicity of arecoline. At a concentration higher than 50 microg/ml, arecoline was shown to be cytotoxic to human buccal fibroblasts in a dose-dependent manner by the alamar blue dye colorimetric assay (P<0.05). In addition, arecoline significantly decreased GST activity in a dose-dependent manner (P<0.05). At concentrations of 100 microg/ml and 400 microg/ml, arecoline reduced GST activity about 21% and 46%, respectively, during a 24 h incubation period. However, arecoline at any test dose did not increase lipid peroxidation in the present human buccal fibroblast test system. The addition of extracellular nicotine acted synergistically on the arecoline-induced cytotoxicity. Arecoline at a concentration of 50 microg/ml caused about 30% of cell death over the 24 h incubation period. However, 2.5 mM nicotine enhanced the cytotoxic response and caused about 50% of cell death on 50 microg/ml arecoline-induced cytotoxicity. Taken together, arecoline may render human buccal mucosal fibroblasts more vulnerable to other reactive agents in cigarettes via GST reduction. The compounds of tobacco products may act synergistically in the pathogenesis of oral mucosal lesions in areca quid chewers. The data presented here may partly explain why patients who combined the habits of areca quid chewing and cigarette smoking are at greater risk of contracting oral cancer. MeSH Terms:
From PubMed | |
|
| ||
| 22 | Increased oxidative stress in dimethylnitrosamine-induced liver
fibrosis in the rat: effect of N-acetylcysteine and interferon-alpha.
Vendemiale G, Grattagliano I, Caruso ML, Serviddio G, Valentini AM,
Pirrelli M, Altomare E. Department of Internal and Public Medicine (DIMIMP), University of Bari, Bari, Italy. g.vendemiale@semeiotica.uniba.it Oxidative stress may represent a common link between chronic liver
damage and hepatic fibrosis. Antioxidants and interferon seem to protect
against hepatic stellate cell (HSC) activation and liver fibrosis. This
study evaluated (1) the effect of the profibrotic agent
dimethylnitrosamine (DMN) on the hepatic oxidative balance in the rat; (2)
the role played by the antioxidant agent N-acetylcysteine (NAC); and (3)
the antifibrotic effects of two different types of interferon-alpha:
recombinant alpha-2b (rIFN-alpha) and leukocyte alpha (LeIFN-alpha). Five
groups of rats received: (1) saline; (2) DMN; (3) DMN + NAC; (4) DMN +
rIFN-alpha; and (5) DMN + LeIFN-alpha. Oxidative balance was evaluated by
hepatic glutathione, TBARs, protein carbonyl, and sulfhydryl
determination. Fibrosis was determined by hepatic hydroxyproline content
and fibronectin (FN) staining (immunohistochemistry). DMN rats showed a
diffuse FN deposition, an impaired oxidative balance, and higher hepatic
hydroxyproline levels compared to that of controls. NAC administration
significantly reduced FN deposition, increased hepatic glutathione, and
decreased TBARs and protein carbonyls. Administration of IFN-alpha exerted
different effects according to the type used. Both IFNs decreased FN
deposition; however, LeIFN-alpha significantly improved histology and
oxidative parameters compared to those of untreated DMN and rats treated
with rIFN-alpha. This study shows the role of free radicals in this model
of hepatic fibrosis; the protective effect of NAC against liver fibrosis;
and the antifibrotic effect exerted by IFN-alpha (particularly
LeIFN-alpha) independent of its antiviral activity. MeSH Terms:
From PubMed | |
|
| ||
| 23 | Areca nut extract and arecoline induced the cell cycle arrest but
not apoptosis of cultured oral KB epithelial cells: association of
glutathione, reactive oxygen species and mitochondrial membrane
potential.
Chang MC, Ho YS, Lee PH, Chan CP, Lee JJ, Hahn LJ, Wang YJ, Jeng JH.
Team of Biomedical Science, Chang-Gung Institute of Nursing, Taiwan. There are 600 million betel quid (BQ) chewers in the world. BQ chewing is a major etiologic factor of oral cancer. Areca nut (AN) and arecoline may inhibit the growth of oral mucosal fibroblasts (OMF) and keratinocytes. In this study, AN extract (100-800 microg/ml) and arecoline (20-120 microM) inhibited the growth of oral KB cells by 36-90 and 15-75%, respectively. Exposure to arecoline (> 0.2 mM) for 24 h induced G(2)/M cell cycle arrest of OMF and KB cells. Areca nut extract (> 400 microg/ml) also induced G(2)/M arrest of KB cells, being preceded by S-phase arrest at 7-h of exposure. No evident sub-G(0)/G(1) peak was noted. Marked retraction and intracellular vacuoles formation of OMF and KB cells were observed. Glutathione (GSH) level, mitochondrial membrane potential (Deltabetam) and H(2)O(2) production of KB cells were measured by flow cytometry. GSH level [indicated by 5-chloromethyl-fluorescein (CMF) fluorescence] was depleted by 24-h exposure of KB cells to arecoline (0.4-1.2 mM) and AN extract (800-1200 microg/ml), with increasing the percentage of cells in low CMF fluorescence. By contrast, arecoline (0.1-1.2 mM) and AN extract (800-1200 microg/ml) induced decreasing and increasing H(2)O(2) production (by 2',7'-dichloro- fluorescein fluorescence), respectively. Hyperpolarization of Deltabetam (increasing of rhodamine uptake) was noted by 24-h exposure of KB cells to arecoline (0.4-1.2 mM) and AN extract (800-1200 microg/ml). AN extract (100- 1200 microg/ml) and arecoline (0.1-1.2 mM) induced little DNA fragmentation on KB cells within 24 h. These results indicate that AN ingredients are crucial in the pathogenesis of oral submucous fibrosis (OSF) and oral cancer by differentially inducing the dysregulation of cell cycle control, Deltabetam, GSH level and intracellular H(2)O(2) production, these events being not coupled with cellular apoptosis. MeSH Terms:
From PubMed | |
|
| ||
| 24 | Chemoprevention of aflatoxin B1-initiated and carbon
tetrachloride-promoted hepatocarcinogenesis in the rat by green tea.
Qin G, Ning Y, Lotlikar PD. Fels Institute for Cancer Research and Molecular Biology and the Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140, USA. Chemoprevention of hepatocarcinogenesis by green tea (GT) has been examined in young male Fischer rats fed AIN-76A diet with aflatoxin B1 (AFB1) and CCl4 as the initiator and promoter, respectively. Animals were administered AFB1 (0.25 mg/kg body wt ip) twice a week for 2 weeks, and 2 weeks later, CCl4 was injected (0.8 ml/kg body wt ip) once per week for 11 weeks. Rats given 0.5% GT in their drinking water before and during initiation (0-4 wk) or during promotion (6-16 wk) or throughout the experimental period were sacrificed 24 hours after the last dose of CCl4. Bromodeoxyuridine incorporation as a measure of cell proliferation and glutathione S-transferase placentalform- and gamma-glutamyl transpeptidase-positive hepatic foci were analyzed by histochemical methods. Feeding of GT during initiation or promotion inhibited the number of glutathione S-transferase placental form- and gamma-glutamyl transpeptidase-positive hepatic foci by 30-40% and the area and volume by 50%. GT treatment throughout the period inhibited the number of both types of hepatic foci by 60% and the area and volume by 75-80%. Cell proliferation was inhibited 35% by GT given during promotion, whereas inhibition was 65% when GT was given during initiation or throughout the period. These results indicate that GT feeding inhibits initiation and promotion steps of AFB1 hepatocarcinogenesis and that the inhibition of cell proliferation is responsible for the inhibition of promotion. MeSH Terms:
From PubMed | |
|
| ||
| 25 | Attenuation by oral N-acetylcysteine of bleomycin-induced lung
injury in rats.
Cortijo J, Cerda-Nicolas M, Serrano A, Bioque G, Estrela JM, Santangelo
F, Esteras A, Llombart-Bosch A, Morcillo EJ. Dept of Pharmacology, University of València, Spain. Antioxidant therapy may be useful in diseases with impaired oxidant-antioxidant balance such as pulmonary fibrosis. This study examines the effect of N-acetylcysteine (NAC) on bleomycin-induced lung fibrosis in rats. NAC (3 mmol x kg(-1); oral) was given daily from 1 week prior to a single intratracheal instillation of bleomycin (2.5 U x kg(-1)) or saline, until 14 days postinstillation. NAC partially decreased the augmented collagen deposition in bleomycin-exposed rats (hydroxyproline content was 4,354+/-386 and 3,416+/-326 microg x lung(-1) in vehicle-treated and NAC-treated rats, respectively; p < 0.05). The histological assessment using a semiquantitative score showed less collagen deposition and inflammatory cells in NAC-treated rats compared to those receiving bleomycin alone. NAC failed to inhibit the bleomycin-induced increases in lung wet weight and in cell counts and protein levels of bronchoalveolar lavage fluid, but significantly increased total glutathione and taurine levels in bronchoalveolar lavage fluid. These results indicate that oral N-acetylcysteine improves the pulmonary antioxidant protection and may be useful in reducing lung damage produced by bleomycin. MeSH Terms:
From PubMed | |
|
| ||
| 26 | Methyl ethyl ketone peroxide ingestion: toxicity and outcome in a
6-year-old child.
Bates N, Driver CP, Bianchi A. National Poisons Information Service, Medical Toxicology Unit, London SE14 5ER United Kingdom. A 6-year-old boy developed respiratory distress, metabolic acidosis, severe esophageal and gastric burns, and a coagulopathy after ingestion of an unknown volume of methyl ethyl ketone peroxide (MEKP) in dimethyl phthalate. He was discharged from the pediatric intensive care unit 19 days postingestion but subsequently developed a stricture of the gastroesophageal junction and complete fibrosis of the middle third of the stomach, necessitating gastric resection and reconstruction. He was discharged 93 days postingestion on a program of dilation for the residual esophageal stricture. MEKP acts by initiating lipid peroxidation via free radical production that results in cellular dysfunction and death. Acetylcysteine, a glutathione precursor and possible free radical scavenger, may be of use in severe MEKP poisoning. This case demonstrates the severe effects that some industrial chemicals can have both systemically and locally at the point of contact with the gastrointestinal tract, as well as the long-term management required to ensure good quality of life. MeSH Terms:
From PubMed | |
|
| ||
| 27 | Characterization and functional implications of the RNA binding
properties of nuclear factor TDP-43, a novel splicing regulator of CFTR
exon 9.
Buratti E, Baralle FE. International Center for Genetic Engineering and Biotechnology (ICGEB) 34012 Trieste, Italy. Variations in a polymorphic (TG)m sequence near exon 9 of the human CFTR gene have been associated with variable proportions of exon skipping and occurrence of disease. We have recently identified nuclear factor TDP-43 as a novel splicing regulator capable of binding to this element in the CFTR pre-mRNA and inhibiting recognition of the neighboring exon. In this study we report the dissection of the RNA binding properties of TDP-43 and their functional implications in relationship with the splicing process. Our results show that this protein contains two fully functional RNA recognition motif (RRM) domains with distinct RNA/DNA binding characteristics. Interestingly, TDP-43 can bind a minimum number of six UG (or TG) single-stranded dinucleotide stretches, and binding affinity increases with the number of repeats. In particular, the highly conserved Phe residues in the first RRM region play a key role in nucleic acid recognition. MeSH Terms:
From PubMed | |
|
| ||
| 28 | Antioxidant status in erythrocytes of cystic fibrosis children.
Laskowska-Klita T, Chelchowska M. Department of Biochemistry, National Research Institute of Mother and Child, Warszawa, Poland. biochem@imid.med.pl Activities of superoxide dismutase, catalase and glutathione peroxidase in erythrocytes of cystic fibrosis children were studied in order to estimate the severity of their deficiency. Our results point to increased susceptibility of erythrocytes of cystic fibrosis subjects to oxidative injury and indicate that the antioxidant status of patients should be carefully monitored. MeSH Terms:
From PubMed | |
|
| ||
| 29 | Regulation of anion secretion by nitric oxide in human airway
epithelial cells.
Duszyk M. Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada. marek.duszyk@ualberta.ca Nitric oxide (NO) is continuously produced and released in human airways, but the biological significance of this process is unknown. In this study, we have used Calu-3 cells to investigate the effects of NO on transepithelial anion secretion. An inhibitor of NO synthase, NG-nitro-L-arginine methyl ester, reduced short- circuit current (I(sc)), whereas an NO donor, S-nitrosoglutathione (GSNO), increased I(sc), with an EC50 approximately 1.2 microM. The NO-activated current was inhibited by diphenylamine-2-carboxylate, clotrimazole, and charybdotoxin. Selective permeabilization of cell membranes indicated that NO activated both apical anion channels and basolateral potassium channels. An inhibitor of soluble guanylate cyclase, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, prevented activation of I(sc) by NO but not by 8-bromo-cGMP, suggesting that NO acts via a cGMP-dependent pathway. Sequential treatment of cells with forskolin and GSNO or 1-ethyl-2-benzimidazolinone and GSNO showed additive effects of these chemicals on I(sc). Interestingly, GSNO elevated intracellular Ca2+ concentration ([Ca2+]i) but had no effect on I(sc) activated by thapsigargin. These results show that NO activates transepithelial anion secretion via a cGMP-dependent pathway that involves cross talk between NO and [Ca2+]i. MeSH Terms:
From PubMed | |
|
| ||
| 30 | Role of areca nut in betel quid-associated chemical carcinogenesis:
current awareness and future perspectives.
Jeng JH, Chang MC, Hahn LJ. Laboratory of Dental Pharmacology and Toxicology, College of Medicine, Graduate Institute of Clinical Dental Science, National Taiwan University, No. 1 Chang-Te Street, Taipei, Taiwan. huei@ha.mc.ntu.edu.tw Betel quid (BQ)-chewing is a popular oral habit with potential links to the occurrence of oral cancer. Many of the literature-based studies reveal that areca nut (AN) extract may demonstrate mutagenic and genotoxic effects, in addition to inducing preneoplastic as well as neoplastic lesions in experimental animals. Areca nut should, thus, be highly suspected as a human carcinogen. Toxicity studies relating to AN-contained polyphenols and tannins are not conclusive, with both carcinogenic and anti-carcinogenic effects being reported. The mutagenicity and genotoxicity of areca alkaloids has been detected by many short-term assays. However, their genotoxicity to oral fibroblasts and keratinocytes, the target cells of BQ, has not been identified. It would thus appear that AN toxicity is not completely due to its polyphenol, tannin and alkaloid content. The single agent which is responsible for AN carcinogenicity awaits further clarification. Reactive oxygen species produced during auto-oxidation of AN polyphenols in the BQ-chewer's saliva, are crucial in the initiation and promotion of oral cancer. Nitrosation of areca alkaloids also produces AN-specific nitrosamines, that have been demonstrated to be mutagenic, genotoxic and are capable of inducing tumors in experimental animals. Arecaidine and AN extract are further suggested to be tumor promoters. Antioxidants such as glutathione and N-acetyl-L-cysteine can potentially prevent such AN-elicited cytotoxicity. Further studies are needed to delineate the metabolism of AN ingredient and their roles in the multi-step chemical carcinogenesis, in order to enhance the success of the future chemoprevention of oral cancer and oral submucous fibrosis. Publication Types:
From PubMed | |
|
| ||
| 31 | Antioxidant imbalance in the lungs of cystic fibrosis transmembrane
conductance regulator protein mutant mice.
Velsor LW, van Heeckeren A, Day BJ. Department of Medicine, National Jewish Medical and Research Center, Denver, Colorado 80206, USA. Recent studies suggest that the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) protein modulates epithelial reduced glutathione (GSH) transport and when defective creates an antioxidant imbalance. To test whether the CFTR protein modulates lung antioxidant defenses in vivo, epithelial lining fluid (ELF) and lung tissue from CFTR knockout (CFTR-KO) and wild-type (WT) mice were compared for GSH content and the activities of glutathione reductase, glutathione peroxidase, and gamma-glutamyltransferase. In the CFTR-KO mice, the ELF concentration of GSH was decreased (51%) compared with that in WT mice. The concentration of GSH in the lung tissue of CFTR-KO mice, however, was not significantly different from that in WT mice. The activities of glutathione reductase and glutathione peroxidase in the lung tissue of CFTR-KO mice were significantly increased compared with those in WT mice (48 and 28%, respectively). Tissue lipid and DNA oxidation were evaluated by measurement of thiobarbituric acid-reactive substances and 8-hydroxy-2'-deoxyguanosine, respectively. The levels of thiobarbituric acid-reactive substances and 8-hydroxy-2'-deoxyguanosine in the lung tissue of CFTR-KO mice were significantly increased compared with those in WT mice. These data support our hypothesis that a mutation in the CFTR gene can affect the antioxidant defenses in the lung and may contribute to the exaggerated inflammatory response observed in CF. MeSH Terms:
From PubMed | |
|
| ||
| 32 | Synthetic chloride channel restores glutathione secretion in cystic
fibrosis airway epithelia.
Gao L, Broughman JR, Iwamoto T, Tomich JM, Venglarik CJ, Forman HJ.
Department of Environmental Health Sciences, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA. Cystic fibrosis (CF), an inherited disease characterized by defective epithelial Cl- transport, damages lungs via chronic inflammation and oxidative stress. Glutathione, a major antioxidant in the epithelial lung lining fluid, is decreased in the apical fluid of CF airway epithelia due to reduced glutathione efflux (Gao L, Kim KJ, Yankaskas JR, and Forman HJ. Am J Physiol Lung Cell Mol Physiol 277: L113-L118, 1999). The present study examined the question of whether restoration of chloride transport would also restore glutathione secretion. We found that a Cl- channel-forming peptide (N-K4-M2GlyR) and a K+ channel activator (chlorzoxazone) increased Cl- secretion, measured as bumetanide-sensitive short-circuit current, and glutathione efflux, measured by high-performance liquid chromatography, in a human CF airway epithelial cell line (CFT1). Addition of the peptide alone increased glutathione secretion (181 +/- 8% of the control value), whereas chlorzoxazone alone did not significantly affect glutathione efflux; however, chlorzoxazone potentiated the effect of the peptide on glutathione release (359 +/- 16% of the control value). These studies demonstrate that glutathione efflux is associated with apical chloride secretion, not with the CF transmembrane conductance regulator per se, and the defect of glutathione efflux in CF can be overcome pharmacologically. MeSH Terms:
From PubMed | |
|
| ||
| 33 | Rethinking cystic fibrosis pathology: the critical role of abnormal
reduced glutathione (GSH) transport caused by CFTR mutation.
Hudson VM. Brigham Young University, Provo, UT 84602, USA. valerie_hudson@byu.edu Though the cause of cystic fibrosis (CF) pathology is understood to be the mutation of the CFTR protein, it has been difficult to trace the exact mechanisms by which the pathology arises and progresses from the mutation. Recent research findings have noted that the CFTR channel is not only permeant to chloride anions, but other, larger organic anions, including reduced glutathione (GSH). This explains the longstanding finding of extracellular GSH deficit and dramatically reduced extracellular GSH:GSSG (glutathione disulfide) ratio found to be chronic and progressive in CF patients. Given the vital role of GSH as an antioxidant, a mucolytic, and a regulator of inflammation, immune response, and cell viability via its redox status in the human body, it is reasonable to hypothesize that this condition plays some role in the pathogenesis of CF. This hypothesis is advanced by comparing the literature on pathological phenomena associated with GSH deficiency to the literature documenting CF pathology, with striking similarities noted. Several puzzling hallmarks of CF pathology, including reduced exhaled NO, exaggerated inflammation with decreased immunocompetence, increased mucus viscoelasticity, and lack of appropriate apoptosis by infected epithelial cells, are better understood when abnormal GSH transport from epithelia (those without anion channels redundant to the CFTR at the apical surface) is added as an additional explanatory factor. Such epithelia should have normal levels of total glutathione (though perhaps with diminished GSH:GSSG ratio in the cytosol), but impaired GSH transport due to CFTR mutation should lead to progressive extracellular deficit of both total glutathione and GSH, and, hypothetically, GSH:GSSG ratio alteration or even total glutathione deficit in cells with redundant anion channels, such as leukocytes, lymphocytes, erythrocytes, and hepatocytes. Therapeutic implications, including alternative methods of GSH augmentation, are discussed. Publication Types:
From PubMed | |
|
| ||
| 34 | S-nitrosoglutathione increases cystic fibrosis transmembrane
regulator maturation.
Zaman K, McPherson M, Vaughan J, Hunt J, Mendes F, Gaston B, Palmer LA.
Department of Pediatrics, University of Virginia, Charlottesville, Virgina 22908, USA. Endogenous S-nitrosoglutathione (GSNO) is known to increase the
expression of certain proteins at concentrations present in the normal
human airway. We hypothesized that GSNO would increase expression and
maturation of the cystic fibrosis transmembrane conductance regulator
(CFTR). Cells expressing DeltaF508 and wild type CFTR were exposed to GSNO
and analyzed for expression and maturation by Western blot analysis.
Physiologically relevant concentrations of GSNO resulted in dose- and
time-dependent increases in expression. The GSNO-induced increases were
eliminated by cycloheximide, suggesting a posttranscriptional effect.
Unlike proteasome inhibitors, GSNO resulted in an increase CFTR
maturation. The GSNO effect could be reversed by dithiothreitol and
inhibited by acivicin, a gamma glutamyl transpeptidase inhibitor. These
observations suggest that GSNO leads to maturation of mutated DeltaF508
CFTR, a process associated with restoration of CFTR function. Because
endogenous levels of GSNO are low in the cystic fibrosis (CF) airway,
these results raise the possibility that GSNO replacement therapy could be
an effective treatment for CF. MeSH Terms:
From PubMed | |
|
| ||
| 35 | The role of antioxidant vitamins (C and E), selenium and Nigella
sativa in the prevention of liver fibrosis and cirrhosis in rabbits: new
hopes.
Turkdogan MK, Agaoglu Z, Yener Z, Sekeroglu R, Akkan HA, Avci ME.
Department of Internal Medicine, Faculty of Medicine, Yuzuncu Yil University, Van, Turkey. This experiment was carried out to investigate the role of antioxidants such as vitamin C and E, selenium and Nigella sativa (NS) on the prevention of carbon tetrachloride (CCl4)-induced liver fibrosis in rabbits. It was found that superoxide dismutase (SOD) values in all of the treated groups were significantly lower than those of the control at 12th week of experiment (p < 0.05), while at 6th week and 12th week of experiment glutathione peroxidase (GSH-Px) values in the vitamin C treated group were significantly different from the control (p < 0.05). Histopathologically, hepatocellular necrosis, degeneration and advanced fibrosis were found in the control group. Lesions were minor and only confined to midzonal regions without centrilobular necrosis and fibrosis in the NS treated animals (group B). The lesions observed in the vitamin C treated animals (group C) were similar to that of the control group. Parenchymal changes with fibrosis were less in selenium and vitamin E treated animals (group D) than in those of the control group, but more obvious than in NS group. Histopathological findings demonstrate that NS might, at least partly, be successful in the prevention of liver fibrosis in rabbits. Vitamin E plus selenium had little therapeutic effect and vitamin C seemed to be ineffective, as far as the results of this study are concerned. MeSH Terms:
From PubMed | |
|
| ||
| 36 | Oxidative stress in cystic fibrosis: dietary and metabolic
factors.
Wood LG, Fitzgerald DA, Gibson PG, Cooper DM, Collins CE, Garg ML.
Discipline of Nutrition and Dietetics, University of Newcastle, Callaghan, New South Wales, Australia. OBJECTIVE: To examine oxidative stress in CF by measuring 8-iso-PGF2alpha and antioxidant defenses, in relation to dietary intake, immune function and clinical status. METHODS: We measured total plasma concentrations of 8-iso-PGF2alpha and dietary antioxidants (vitamin E, vitamin C, beta-carotene), erythrocyte antioxidant enzyme activities (glutathione peroxidase and superoxide dismutase), lung function and dietary intake in 21 CF subjects and 21 healthy age- and gender-matched controls. RESULTS: Total plasma 8-iso-PGF2alpha concentration (median [quartile 1-quartile 3]) was significantly higher in CF subjects compared to controls (214 pg/mL (155-331) vs. 135 pg/mL (101-168), p = 0.001). Neutrophil, monocyte and total white cell counts were elevated in the CF group and these correlated with 8-iso-PGF2alpha concentration. Despite similar dietary intake, lower plasma antioxidant concentrations were observed in the CF group (vitamin E, p < 0.001, vitamin C, p = 0.004, beta-carotene, p = 0.001). 8-iso-PGF2alpha correlated negatively with plasma vitamin E, C and beta-carotene concentrations. CONCLUSION: Oxidative stress is increased in CF patients, despite normal dietary antioxidant intake. The immune response appears to be a key factor causing oxidative stress. Antioxidant intervention aimed at reducing oxidative stress in CF needs to be assessed. MeSH Terms:
From PubMed | |
|
| ||
| 37 | Adenylate kinase as a virulence factor of Pseudomonas
aeruginosa.
Markaryan A, Zaborina O, Punj V, Chakrabarty AM. Department of Microbiology & Immunology, University of Illinois College of Medicine, 835 South Wolcott Ave., Chicago, IL 60612, USA. Adenylate kinase (AK; ATP:AMP phosphotransferase, EC 2.7.4.3) is a ubiquitous enzyme that contributes to the homeostasis of adenine nucleotides in eukaryotic and prokaryotic cells. AK catalyzes the reversible reaction Mg. ATP + AMP <--> Mg. ADP + ADP. In this study we show that AK secreted by the pathogenic strains of Pseudomonas aeruginosa appears to play an important role in macrophage cell death. We purified and characterized AK from the growth medium of a cystic fibrosis isolate strain of P. aeruginosa 8821 and hyperproduced it as a fusion protein with glutathione S-transferase. We demonstrated enhanced macrophage cell death in the presence of both the secreted and recombinant purified AK and its substrates AMP plus ATP or ADP. These data suggested that AK converts its substrates to a mixture of AMP, ADP, and ATP, which are potentially more cytotoxic than ATP alone. In addition, we observed increased macrophage killing in the presence of AK and ATP alone. Since the presence of ATPase activity on the macrophages was confirmed in the present work, external macrophage-effluxed ATP is converted to ADP, which in turn can be transformed by AK into a cytotoxic mixture of three adenine nucleotides. Evidence is presented in this study that secreted AK was detected in macrophages during infection with P. aeruginosa. Thus, the possible role of secreted AK as a virulence factor is in producing and keeping an intact pool of toxic mixtures of AMP, ADP, and ATP, which allows P. aeruginosa to exert its full virulence. MeSH Terms:
From PubMed | |
|
| ||
| 38 | 5'-Methylthioadenosine administration prevents lipid peroxidation
and fibrogenesis induced in rat liver by carbon-tetrachloride
intoxication.
Simile MM, Banni S, Angioni E, Carta G, De Miglio MR, Muroni MR,
Calvisi DF, Carru A, Pascale RM, Feo F. Department of Biomedical Sciences, University of Sassari, Italy. BACKGROUND: 5'-Methylthioadenosine (MTA), a product of S-adenosylmethionine (SAM) catabolism, could undergo oxidation by mono-oxygenases and auto-oxidation. MTA and SAM effects on oxidative liver injury were evaluated in CCl4-treated rats. METHODS: Male Wistar rats were killed 1-48 h after poisoning with a single intraperitoneal CCl4 dose (0.15 ml/100 g) or with the same dose twice a week for 14 weeks. Daily doses of MTA or SAM (384 micromol/kg), started 1 week before acute CCl4 administration or with chronic treatment, were continued up to the time of sacrifice. RESULTS: Acute and chronic CCl4 intoxication decreased MTA and, to a lesser extent, SAM and reduced glutathione (GSH) liver levels. MTA administration increased liver MTA without affecting SAM and GSH. SAM treatment caused complete/partial recovery of these compounds. MTA and, to a lesser extent, SAM prevented an increase in liver phospholipid hydroperoxides in acutely and chronically intoxicated rats and in prolyl hydroxylase activity and trichrome-positive areas in chronically treated rats. MTA prevented upregulation of Tgf-beta1, Collagen-alpha1 (I) and Tgf-alpha genes in liver of chronically intoxicated rats, and TGF-beta1-induced transdifferentiation to myofibroblasts and growth stimulation by platelet-derived growth factor-b of stellate cells in vitro. CONCLUSIONS: MTA and SAM protect against oxidative liver injury through partially different mechanisms. MeSH Terms:
From PubMed | |
|
| ||
| 39 | Relationship of fiber surface iron and active oxygen species to
expression of procollagen, PDGF-A, and TGF-beta(1) in tracheal explants
exposed to amosite asbestos.
Dai J, Churg A. Department of Pathology, University of British Columbia, Vancouver, British Columbia, Canada. To investigate the role of iron and active oxygen species (AOS) in asbestos-induced fibrosis, we loaded increasing amounts of Fe(II)/Fe(III) onto the surface of amosite asbestos fibers and then applied the fibers to rat tracheal explants. Explants were harvested after 7 d in air organ culture. Asbestos by itself doubled procollagen gene expression, and a further increase was seen with increasing iron loading; actual collagen content measured as hydroxyproline was increased in a similar pattern. Iron loading also increased gene expression of platelet-derived growth factor (PDGF)-A and transforming growth factor (TGF)-beta(1). Neither asbestos alone nor iron-loaded asbestos affected gene expression of PDGF-B, tumor necrosis factor-alpha, or TGF-alpha. The AOS scavenger tetramethylthiourea or treatment of fibers with the iron chelator deferoxamine prevented asbestos-induced increases in procollagen, PDGF-A, and TGF-beta gene expression, whereas glutathione had no effect. The proteasome inhibitor MG-132 abolished asbestos-induced increases in procollagen gene expression but did not affect increases in PDGF-A or TGF-beta(1) expression, whereas the extracellular signal-regulated protein kinase (ERK) inhibitor PD98059 had exactly the opposite effect. We conclude that surface iron as well as the iron-catalyzed generation of AOS play a role in asbestos-induced matrix (procollagen) production and that this process is driven in part through oxidant-induced nuclear factor kappa B activation. Surface iron and AOS also play a role in PDGF-A and TGF-beta gene expression, but through an ERK-dependent mechanism. MeSH Terms:
From PubMed | |
|
| ||
| 40 | Sequential changes in hepatocarcinogenesis induced by
diethylnitrosamine plus thioacetamide in Fischer 344 rats: induction of
gankyrin expression in liver fibrosis, pRB degradation in cirrhosis, and
methylation of p16(INK4A) exon 1 in hepatocellular carcinoma.
Park TJ, Kim HS, Byun KH, Jang JJ, Lee YS, Lim IK. Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon, Korea. To clarify the sequential changes in pRB and p16 during different stages of hepatocarcinogenesis such as fibrosis, cirrhosis, hepatocellular adenoma (HCA), and hepatocellular carcinoma (HCC), male Fischer 344 rats were singly injected with diethylnitrosamine (DEN), immediately followed with phenobarbital for 1 wk and then thioacetamide (TAA) for 39 wk in drinking water. Rats were killed at 9, 20, 30, and 40 wk after DEN initiation and changes of pRB level, p16 gene hypermethylation, and in vivo gankyrin expression were examined. Histologic examination showed stepwise appearances of fibrosis, cirrhosis, HCA, and HCC at weeks 9, 20, 30, and 40, respectively. Hypermethylation of p16 exon 1 was not found until HCA but appeared in 50% of the rats with HCC accompanied by complete los | |