PubMed Health⌕ Search

Biomedical subjects

C Tagesson

Publications and source records attributed to C Tagesson.

At least 19 recordsLinked to original sources
PubMed1992

Group I phospholipase A2 mRNA expression in rat glandular stomach and pancreas. Ontogenic development and effects of cortisone acetate.

The postnatal development of group I phospholipase A2 (group I PLA2) in the glandular stomach and pancreas of neonatal rats was investigated. The amounts of group I PLA2 mRNA (and also the PLA2 enzymatic activity) in the glandular stomach mucosa increased with age in 3-60-day-old animals. This postnatal development of rat stomach group I PLA2 mRNA agreed with that of group I PLA2 mRNA of the rat pancreas, and thus seems to follow the general development of the gastrointestinal tract during the neonatal period. The latter was further supported by the finding that maturation of group I PLA2 in both the stomach and pancreas was induced precociously in rats treated with cortisone acetate. It is suggested that the stomach group I PLA2 is involved in mucosal eicosanoid production.

Animals↗
PubMed1992

Rapid and sensitive detection of hydroxyl radicals formed by activated neutrophils in the presence of chelated iron: hydroxylation of deoxyguanosine to 8-hydroxydeoxyguanosine.

Hydroxyl radicals (OH) can react with deoxyguanosine (dG) leading to the formation of 8-hydroxydeoxyguanosine (8OHdG). In this study, this has been used to detect the hydroxyl radicals formed when human polymorphonuclear leukocytes (PMNL) are stimulated with phorbol myristate acetate (PMA) in the presence of chelated iron. Reaction mixtures containing PMNL, PMA, dG and Fe-EDTA were incubated at 37 degrees C, and the formation of 8OHdG was analysed with high-performance liquid chromatography and electrochemical detection. 8OHdG formation was detected at PMA concentrations of 2 nM or higher, and half-maximal 8OHdG formation was found at around 6 nM PMA. Stimulation of 500,000 cells with 10 nM PMA for 20 min resulted in a 500 to 1000-fold increase in 8OHdG formation as compared to unstimulated cells. The 8OHdG formation decreased after addition of hydroxyl radical scavengers (sodium benzoate, dimethylsulfoxide, and mannitol) and increased after addition of platelet-activating factor (PAF), an agent known to stimulate the generation of reactive oxygen metabolites in neutrophils. These results demonstrate that hydroxylation of dG to 8OHdG can be used to determine neutrophil-generated hydroxyl radicals in different experimental systems. Since the analysis of 8OHdG is rapid, sensitive and easy, this may have wide applications in inflammation and cancer research.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1992

Cigarette smoke-induced DNA damage in cultured human lung cells: role of hydroxyl radicals and endonuclease activation.

Cigarette smoke can cause DNA single strand breaks in cultured human lung cells (T. Nakayama et al., Nature, 314 (1985) 462-464) but the mechanisms behind this DNA damage have not been clearly elucidated. In the present study we have investigated the possibility that one of the major constituents in cigarette smoke, hydroquinone, may be important for mediating smoke-induced DNA damage in the human epithelial lung cell line, A 549, and the mechanisms behind this damage. Cells were exposed to cigarette smoke, hydrogen peroxide, or hydroquinone, in the absence and presence of different inhibitors, and the resulting DNA damage was assessed either as DNA single strand break formation or formation of the oxidative DNA adduct, 8-hydroxydeoxyguanosine. It was found that (i) exposure to cigarette smoke, hydrogen peroxide or hydroquinone causes a rapid decrease in the intracellular thiol level and a considerable DNA single strand break formation, (ii) the formation of DNA single strand breaks in cells exposed to cigarette smoke is inhibited by catalase, dimethylthiourea, and o-phenantroline, suggesting that hydroxyl radicals generated from iron-catalyzed hydrogen peroxide dissociation are involved in the DNA damage, (iii) hydroquinone causes considerable DNA strand break formation that is blocked by aurintricarboxylic acid, an inhibitor of endonuclease activation, and by BAPTA, an intracellular calcium chelator, (iv) addition of hydroquinone to a smoke condensate greatly enhances its ability to cause DNA single strand breaks, and (v) smoke, but not hydroquinone, causes formation of 8-hydroxydeoxyguanosine, a DNA damage product induced by the action of hydroxyl radicals on the DNA base, deoxyguanosine. These findings suggest that the ability of cigarette smoke to cause DNA single strand breaks in cultured lung cells is due to mechanisms involving hydroxyl radical attack on DNA and endonuclease activation. They also suggest that hydroquinone is an important contributor to the DNA damaging effect of cigarette smoke on human lung cells.

Cell Line↗
PubMed1992

Hydrogen peroxide release and hydroxyl radical formation in mixtures containing mineral fibres and human neutrophils.

The ability of different mineral fibres (rock wool, glass wool, ceramic fibres, chrysotile A, chrysotile B, amosite, crocidolite, antophyllite, erionite, and wollastonite) to stimulate hydrogen peroxide (H2O2) and hydroxyl radical (OH.) formation in mixtures containing human polymorphonuclear leucocytes (PMNLs) was investigated. In the presence of azide, all the fibres caused considerable H2O2 formation, and about twice as much H2O2 was found in mixtures with the natural fibres (asbestos, erionite, and wollastonite) than in mixtures with the manmade fibres (rock wool, glass wool, and ceramic fibres). In the presence of externally added iron, all the fibres were found to generate OH. and the natural fibres caused about three times more OH. formation than the manmade fibres. In the absence of external iron, there was less OH. formation; however, amosite, crocidolite, antophyllite, erionite, and wollastonite still generated considerable amounts of OH., also under circumstances in which only small amounts of OH. were produced in mixtures with the manmade fibres. These findings indicate that natural fibres generate more H2O2 and OH. than manmade fibres when incubated with PMNLs in the presence of external iron. They also suggest that the natural fibres, amosite, crocidolite, antophyllite, erionite, and wollastonite may act catalytically in the dissociation of H2O2 to OH. in the absence of external iron, whereas manmade fibres such as rock wool, glass wool, and ceramic fibres, do not seem to be able to generate OH. in the absence of external iron.

Asbestos↗
PubMed1992

Platelet-activating factor (PAF-acether) formation in neonatal intestinal mucosa and in cultured intestinal epithelial cells.

We report the presence of platelet-activating factor (PAF-acether; 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) in small-intestinal and colonic mucosa of neonatal rats. The PAF-acether content was higher in the colon than in the small intestine, and was lower in the small intestine of 30-day-old animals than in 14-day-old animals. We also report that cultured intestinal epithelial cells (INT 407) produce PAF-acether when stimulated with the calcium ionophore A23187, and that homogenized INT 407 cells can degrade PAF-acether with the formation of lysoPAF-acether. These findings suggest that intestinal epithelial cells are able to produce and metabolize PAF-acether, a potent mediator of inflammation. The authors propose that this might contribute to the pathophysiology of inflammatory bowel disease.

Animals↗
PubMed1991

Demonstration of a phospholipase A2 inhibitor in human plasma and in plasma from the European hedgehog (Erinaceus europaeus).

1. Endogenous phospholipase A2 (PLA2) inhibitors in human plasma and in plasma from the hedgehog (Erinaceus europaeus) were demonstrated. 2. The PLA2 activity increased 45-fold in human plasma when a PLA2 binding factor was removed. Furthermore, two peaks of PLA2 inhibitory activity were found after DEAE-chromatography. 3. High levels of PLA2 inhibitory activity was found in plasma from the European hedgehog, E. europaeus. 4. The molecular weight was estimated to 140,000. 5. On DEAE-chromatography two peaks were found which were chromatographically similar to the PLA2 inhibitors in human plasma.

Adult↗
PubMed1991

Phospholipase C from Clostridium perfringens stimulates formation and release of platelet-activating factor (PAF-acether) in cultured intestinal epithelial cells (INT 407).

This study demonstrates the ability of phospholipase C from Clostridium perfringens to stimulate the generation of platelet-activating factor (PAF-acether) in cultured intestinal epithelial cells (INT 407). Cells were exposed to phospholipase C for up to 60 min, and the content of PAF-acether within the cells and in the extracellular medium was determined. Phospholipase C caused a time-dependent formation of PAF-acether within the cells and also release of PAF-acether to the medium. In contrast, phospholipase C did not affect the cellular acetylhydrolase activity or the ability of the cells to metabolize extracellularly added 14C-PAF-acether. These findings suggest the possibility that intestinal epithelial cells, when stimulated with a naturally occurring intestinal bacterial toxin, generate and release PAF-acether. The possibility that this might contribute to the pathophysiology of inflammatory bowel disease is discussed.

Cell Line↗
PubMed1991

Hydrogen peroxide stimulates phospholipase A2-mediated arachidonic acid release in cultured intestinal epithelial cells (INT 407).

The mechanisms by which hydrogen peroxide and, for comparison, 4-beta-phorbol-12-myristate-13-acetate (PMA) stimulate release of radiolabeled arachidonic acid (14C-AA) in cultured intestinal epithelial cells (INT 407) were investigated. Both hydrogen peroxide and PMA caused a rapid (3 min) and dose-related intracellular release of free 14C-AA, followed by a dose- and time-dependent release of 14C-AA into the extracellular medium, but hydrogen peroxide was about 50,000 times less effective than PMA in releasing 14C-AA. No 14C-AA was released on stimulation with 4-alpha-phorbol-12,13-di-decanoate (PDD), a phorbol ester that does not activate protein kinase C. The 14C-AA release was reduced by the phospholipase A2 inhibitors nordihydroguaiaretic acid and 4-bromophenacyl bromide and by the calmodulin/protein kinase C inhibitor trifluoperazine and the protein kinase C inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7). However, H-7 was less effective than the other inhibitors in reducing the hydrogen peroxide-stimulated 14C-AA release. The hydrogen peroxide-stimulated, but not the PMA-stimulated, rapid (3 min) 14C-AA release was associated with an increased influx of extracellular calcium. Stimulation of the cells with PMA resulted in phosphorylation of a cellular protein of about 32 kDa, whereas no phosphorylation of this protein was detected after stimulation with hydrogen peroxide. Taken together, these findings indicate that (i) both PMA and hydrogen peroxide may stimulate phospholipase A2-mediated AA release from human intestinal epithelial cells; (ii) this stimulation is brought about via protein kinase C and calmodulin-mediated events; (iii) PMA-stimulated 14C-AA release is associated with phosphorylation of a 32-kDa protein, possibly lipocortin, whereas the hydrogen peroxide-stimulated release is not; and (iv) calmodulin is more important for the hydrogen peroxide-stimulated 14C-AA release than is protein kinase C. The possibility that hydrogen peroxide-evoked AA release may contribute to the mucosal abnormality in Crohn's disease is discussed.

Arachidonic Acid↗
PubMed1990

Cigarette smoke-induced DNA-damage: role of hydroquinone and catechol in the formation of the oxidative DNA-adduct, 8-hydroxydeoxyguanosine.

This study demonstrates the ability of cigarette smoke condensate to generate hydrogen peroxide and to hydroxylate deoxyguanosine (dG) residues in isolated DNA to 8-hydroxydeoxyguanosine (8-OHdG). Both the formation of hydrogen peroxide and that of 8-OHdG in DNA was significantly decreased when catalase or tyrosinase was added to the smoke condensates, and this also occurred when pure hydroquinone or catechol, two major constitutes in cigarette smoke, was used instead of smoke condensate. Moreover, pure hydroquinone and catechol both caused dose-dependent formation of hydrogen peroxide and 8-OHdG, and there was good correlation between the amounts of hydrogen peroxide and 8-OHdG formed. These findings suggest that (i) hydroquinone and catechol may be responsible for the ability of cigarette smoke to cause 8-OHdG formation in DNA, (ii) this oxidative DNA-damage is due to the action of hydroxyl radicals formed during dissociation of hydrogen peroxide and (iii) the hydrogen peroxide in cigarette smoke is generated via autooxidation of hydroquinone and catechol.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1990

Biliary excretion of different sized polyethylene glycols in the cat.

Polyethylene glycol (PEG) 900 is excreted more extensively into bile than mannitol and erythritol. In this study, the biliary recovery of intravenously injected marker molecules was analysed in anaesthetised cats with ligated renal pedicles. It was demonstrated that among polyethylene glycols sized 292-1250 Da, the species sized 1074 Da was maximally excreted in the bile. After 5 h, about 12% of the injected amount of this molecular species was recovered in bile. Both larger and smaller polyethylene glycol molecules had a lower biliary excretion. The distribution of different sized PEGs in the range 766-1250 Da in serum was fairly constant and cannot explain the recovery profile in bile. 14C-Labelled mannitol was recovered in bile to the extent of 0.7% of the amount given i.v. after 5 h, a figure that corresponds to that obtained for polyethylene glycol with a size of 370 Da. Bile/plasma ratios during steady state conditions of labelled PEG 450, PEG 900, PEG 2500 and PEG 4000 were 10, 36, 3 and 4, respectively. The results may be tentatively explained by restricted passage of the larger PEG molecules into the canaliculi, and leakage of the smaller molecules from bile back to plasma.

Animals↗
PubMed1990

Glucocorticoid treatment in ileal Crohn's disease: relief of symptoms but not of endoscopically viewed inflammation.

The effect of prednisolone (20-30 mg daily for six to nine weeks) was studied in eight patients with Crohn's disease and recurrent, preanastomotic ileal inflammation, in respect of symptoms, endoscopic findings and phospholipase A2 activity in the ileal mucosa. The Harvey-Bradshaw Crohn's disease activity index improved significantly, mainly because of reduced frequency of loose stools and diminution of abdominal pain. Endoscopy revealed no corresponding decrease in ileal inflammation, which in all cases persisted after treatment. The phospholipase A2 activity in the ileal mucosa was not altered by prednisolone. In two of three patients with concomitant colitis colonic inflammation improved. The study confirmed earlier reports of good symptomatic relief from glucocorticoid treatment in Crohn's disease of the small bowel, but endoscopy suggests that this improvement was not the result of resolution of small intestinal mucosal inflammation.

Adult↗
PubMed1990

Novel aspect of Crohn's disease: increased content of platelet-activating factor in ileal and colonic mucosa.

Intestinal mucosal content of platelet-activating factor (PAF-acether) was investigated in Crohn's disease. The PAF-acether content was determined in mucosal biopsies from the ileum and colon in Crohn patients (n = 13), and in normal mucosa of control patients (n = 11). PAF-acether was found in both groups and was raised in Crohn patients, both in the ileum (6.3 +/- 4.7 vs. 0.6 +/- 0.4 pmol/g; p less than 0.01) and colon (6.2 +/- 4.2 vs. 0.7 +/- 0.4 pmol/g; p less than 0.01). Colonic PAF-acether content was raised irrespective of the presence of colonic inflammation as judged macroscopically. These findings add further support to the importance of bioactive lipids in inflammatory bowel disease and suggest a possible role for PAF-acether in Crohn's disease.

Adolescent↗
PubMed1990

Phospholipase activation and arachidonic acid release in intestinal epithelial cells from patients with Crohn's disease.

A method for studying the mobilization of free arachidonic acid (AA) in viable isolated human intestinal epithelial cells has been developed and applied to the study of patients with Crohn's disease. Cells were isolated from morphologically unaffected parts of the distal ileum and incubated with 14C-AA; most of the incorporated 14C-AA was then found in phospholipids (mainly phosphatidylcholine) and in a pool of neutral lipids (mainly triacylglycerols). Cells from patients with Crohn's disease incorporated more 14C-AA into their neutral lipids than did cells from control patients. When the labeled cells were stimulated with phospholipase C from Clostridium perfringens or with the calcium ionophore A23187, they released significant amounts of AA, mainly from phosphatidylcholine. There was no difference between cells from Crohn patients and controls in the 14C-AA amounts released, but unstimulated and phospholipase C-stimulated cells from prednisolone-treated Crohn patients released less AA than cells from control patients. The A23187-stimulated AA release was completely inhibited by the phospholipase A2 inhibitor 4-bromophenacyl bromide, whereas the phospholipase C-stimulated release was not. These findings suggest that AA release in human small-intestinal epithelial cells may be caused by calcium-mediated phospholipase A2 activation or by products of microbial phospholipase C activity and that prednisolone reduces the mobilization of free AA in intestinal epithelial cells. They also illustrate the potential use of isolated epithelial cells for revealing mechanisms underlying AA release in the intestinal mucosa in different disease states.

Adult↗
PubMed1990

Phospholipase C from Clostridium perfringens stimulates phospholipase A2-mediated arachidonic acid release in cultured intestinal epithelial cells (INT 407).

The mechanisms by which phospholipase C from Clostridium perfringens stimulates release of arachidonic acid (AA) in cultured intestinal epithelial cells (INT-407) were investigated. INT-407 cells were first allowed to incorporate 14C-labeled AA into their phospholipids; the labeled cells were then exposed to phospholipase C, and the release of free 14C-AA was determined. Phospholipase C caused a rapid (3 min) intracellular rise of free 14C-AA, followed by a considerable, dose- and time-dependent release of 14C-AA into the extracellular medium. For comparison, the calcium ionophore A23187 also caused a rapid mobilization of free 14C-AA, but a much lower extracellular 14C-AA release than phospholipase C during longer (1 h) incubation. The 14C-AA release was accompanied by a degradation of 14C-myo-inositol-labeled phosphatidylinositols and was reduced by the protein kinase C inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7). Both phospholipase C- and A23187-stimulated 14C-AA release was associated with degradation of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol and was reduced by nordihydroguaiaretic acid and 4-bromophenacyl bromide, two known phospholipase A2 inhibitors. In addition, the 14C-AA release was reduced by the calmodulin inhibitors trifluoperazine, compound 48/80, and N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide (W-7). These findings indicate that phospholipase C from C. perfringens stimulates phospholipase A2-mediated AA release from human intestinal epithelial cells and suggest that this stimulation is brought about via processes involving phosphatidylinositol breakdown and activation of calmodulin and protein kinase C. It is possible that this phospholipase C-evoked AA release may contribute to the mucosal pathologic condition in diseases with altered intestinal microbial flora.

Arachidonic Acids↗
PubMed1989

Isolation and characterization of phospholipase A2 from rat lung with affinity chromatography and two-dimensional gel electrophoresis.

A phospholipase A2 (PLA2, EC 3.1.1.4) from rat lung has been isolated and characterized. PLA2 was purified with ion-exchange and affinity chromatography and the purified enzyme was characterized with regard to pH optimum and calcium dependence. The isolated enzyme was also analyzed with two-dimensional gel electrophoresis and identified by Western immunoblots. The enzyme activity was found to be highest at pH 9.5-10.0, with a requirement for calcium, and the molecular mass was estimated to be 12 kDa by means of SDS-polyacrylamide gel electrophoresis. The two-dimensional gel electrophoresis analysis revealed two isoforms of PLA2 with isoelectric points of 7.8 and 9.5. On DEAE-Sepharose, PLA2 eluted as two peaks, one in the flow-through fraction and the other with increased salt concentration. Both peaks contained the same two PLA2 isoforms, as judged by two-dimensional gel electrophoresis. These results demonstrate the presence in rat lung of two isoforms of a calcium-dependent 12 kDa PLA2 with alkaline pH optimum. Using two-dimensional gel electrophoresis, this enzyme can be identified also in rat bronchoalveolar lavage fluid.

Animals↗
PubMed1989

Cigarette smoke potentiates the DNA-damaging effect of manmade mineral fibers.

Epidemiological and experimental studies suggest that manmade mineral fibers (MMMFs) have DNA-damaging and carcinogenic properties. To investigate the hypothesis that cigarette smoke can potentiate MMMF-induced DNA damage, we exposed isolated calf thymus DNA to cigarette smoke condensate and/or three different types of MMMFs: rockwool, glasswool, and ceramic fibers. As an index of DNA damage, the hydroxyl radical-generated formation of 8-hydroxydeoxyguanosine (8OHdG) from deoxyguanosine (dG) was used. All the three fiber types, as well as cigarette smoke condensate alone, caused hydroxylation of dG residues in DNA, and, when smoke was combined with each of the different fibers, rockwool caused a synergistically increased formation of 8OHdG. We suggest that 1) iron-containing MMMFs such as rockwool are able to enhance synergistically cigarette smoke-induced DNA-damage and 2) this damage is caused by hydroxyl radicals.

DNA Damage↗
PubMed1989

Increased peritoneal permeability in acute experimental pancreatitis.

The peritoneal permeability to differently sized dextran molecules; Mw 4,000, 10,000, 20,000, and 40,000 was investigated in rats with bile-induced acute pancreatitis. Following intraperitoneal deposition, repeated blood samples for measurement of the different dextrans were collected. The results showed increased peritoneal permeability to molecules between 4,000-20,000 daltons in animals with pancreatitis, whereas there was no significant difference for molecules of 40,000 daltons compared to healthy control animals. Also, the passage of phospholipase A2 (Mw 14,000) over the peritoneal membrane was increased during pancreatitis. It is suggested that the transperitoneal route may be of pathophysiological importance in the development of the systemic components of severe acute pancreatitis.

Acute Disease↗