| 1. |
- Daré, Elisabetta, et al.
(författare)
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Methylmercury and H2O2 provoke lysosomal damage in human astrocytoma D384 cells followed by apoptosis
- 2001
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Ingår i: Free Radical Biology & Medicine. - Linköping : Elsevier. - 0891-5849 .- 1873-4596. ; 30:12, s. 1347-1356
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Tidskriftsartikel (refereegranskat)abstract
- Methylmercury (MeHg) is a neurotoxic agent acting via diverse mechanisms, including oxidative stress. MeHg also induces astrocytic dysfunction, which can contribute to neuronal damage. The cellular effects of MeHg were investigated in human astrocytoma D384 cells, with special reference to the induction of oxidative-stress-related events. Lysosomal rupture was detected after short MeHg-exposure (1 μM, 1 h) in cells maintaining plasma membrane integrity. Disruption of lysosomes was also observed after hydrogen peroxide (H2O2) exposure (100 μM, 1 h), supporting the hypothesis that lysosomal membranes represent a possible target of agents causing oxidative stress. The lysosomal alterations induced by MeHg and H2O2 preceded a decrease of the mitochondrial potential. At later time points, both toxic agents caused the appearance of cells with apoptotic morphology, chromatin condensation, and regular DNA fragmentation. However, MeHg and H2O2 stimulated divergent pathways, with caspases being activated only by H2O2. The caspase inhibitor z-VAD-fmk did not prevent DNA fragmentation induced by H2O2, suggesting that the formation of high-molecular-weight DNA fragments was caspase independent with both MeHg and H2O2. The data point to the possibility that lysosomal hydrolytic enzymes act as executor factors in D384 cell death induced by oxidative stress.
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| 2. |
- Li, Fang-Yuan, et al.
(författare)
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Dominantly inherited familial myasthenia gravis as a separate genetic entity without involvement of defined candidate gene loci
- 2001
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Ingår i: International Journal of Molecular Medicine. - : Spandidos Publications. - 1107-3756 .- 1791-244X. ; 7:3, s. 289-294
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Tidskriftsartikel (refereegranskat)abstract
- Myasthenia gravis (MG) is a sporadic autoimmune disorder affecting neuromuscular transmission. Very rarely autoimmune myasthenia gravis may be inherited within a family. We present here the genetic analysis of a Hungarian family where nine members from two generations are affected by myasthenia gravis. Genetic characterisation of this unique Hungarian family using linkage analysis and mutation screening excludes the involvement of defined candidate gene loci. These findings point to familial MG as a separate genetic entity. Identification of the underlying genetic defect in this family may greatly enhance our understanding of the pathogenesis of myasthenia gravis.
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| 6. |
- Hertervig, Eva, et al.
(författare)
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Global dispersion of right atrial repolarization in healthy pigs and patients
- 2003
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1651-2006 .- 1401-7431. ; 37:6, s. 329-333
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Tidskriftsartikel (refereegranskat)abstract
- Objective - To investigate the feasibility of monophasic action potential ( MAP) mapping using an electro-anatomical mapping system ( CARTO) in obtaining information on global dispersion of atrial repolarization and to evaluate the role of dispersion of repolarization in the genesis of paroxysmal atrial fibrillation ( PAF). Methods and results - Right atrial MAPs were recorded from 53 +/- 18 sites in 10 healthy pigs and 33 +/- 21 sites in 6 patients with and 4 patients without history of PAF. In pigs, the global dispersions of activation time ( AT), MAP duration and end of repolarization time ( EOR), 70 +/- 8, 95 +/- 18 and 121 +/- 28 ms, respectively, were significantly greater than those among 10, 20 and 30 sites. In patients with PAF, the global dispersions of MAP duration and EOR ( 128 +/- 10 and 149 +/- 31 ms) were significantly greater than those in patients without PAF ( 84 +/- 10 and 91 +/- 17 ms). Conclusion - MAP mapping using the CARTO system was feasible in experimental and clinical settings in obtaining information on global dispersion of atrial repolarization. The number of recording sites could significantly affect repolarization parameters. The dispersions of atrial repolarization were significantly greater in patients with PAF than those without, suggesting the involvement of an increased dispersion of repolarization in the genesis of PAF.
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| 7. |
- Li, Fang-Yuan
(författare)
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Genetic study of autosomal dominant progressive external ophthalmoplegia and familial myasthenia gravis : linkage analysis, candidate gene cloning and mutation detection
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Identification of genes responsible for familial human diseases is a major task of medical genetics. In this process, linkage analysis, candidate gene screening and mutation detection are the three major steps (Paper I-VI). The purpose of this study was to elucidate the genetic backgrounds of autosomal dominant progressive external ophthalmoplegia (adPEO) and familial inyasthenia gravis (FMG). The methods applied in this study for linkage analysis and repeat expansion were tested in a family with oculopharyngeal muscular dystrophy (OMPD). The results supported the linkage of this family to chromosome 14q I 1.2-q 13, which had been reported, and did not reveal any expanded CAG/CTG repeats in this family. (Paper I) A genome wide linkage screening was first applied to map the disease locus in a large Pakistani family with adPEO, commonly considered as a mitochondrial disorder because of the finding of multiple deletions of mtDNA. The disease locus was assigned to an I I cM region in chromosome 1 Oq23 -24, and taken together with previously published findings in a single Finnish family a critical region of 7 cM between DlOS198 and DIOS1795 was revealed. (Paper II) One EST (expressed sequence tag) homologous to yeast mitochondrial RNA splice 4 (MRS4) within the critical region was identified. The gene, hMRS314, was cloned and found to have two splicing forms corresponding to a 364 aa and a 177 aa form. Northern blot analysis showed that both forms are ubiquitously expressed, the 177 aa form at comparable levels in the different tissues and the 364 aa form at a relative abundance in skeletal muscle, heart and liver. The mitochondrial protein localization was demonstrated in targeting experiments and in yeast compensation experiments the growth defects of double knockouts of mrs3 degrees and 4degrees growth was restored. The yeast homologues MRS3 and 4, identified by BLAST searching, are members of the gene superfamily of mitochondrial carrier family (MCF). The conservative structure of MCF is well kept in hMRS314 as revealed by multi-alignment of hMRS3/4 with other members of MCF. DNA sequencing of this gene did not show any differences between the adPEO patients and the control. (Paper III) Another gene, Twinkle was cloned from the critical region. Twinkle encodes 684 aa while Twinky, the splice form, encodes 582 aa. BLAST searching showed homology to T7 primase/helicase, and the mitochondrial nucleoid localization demonstrated in targeting experiments. At Western blotting Twinkle was found to form high order multimers while Twinky was detected as a monomer. Multimerization is a feature of the family of ring helicase, which T7 primase/helicase belongs to. A total of 11 mutations were found in 12 families with adPEO including the two reported chromosome 10q-linked families. Targeting and multimerization experiments did not show any differences between the mutants and the wildtype. (Paper IV) A unique Hungarian family was genetically characterized, in which ten members were affected by dominantly inherited myasthenia gravis (MG). The possible involvement of known candidate genes was excluded by mutation screening and linkage analyses of gene loci reported to be mutated in the closely related congenital myasthenia syndrome or linked to MG from association studies. A variant of anticipation was observed in this family RED analysis was therefore carried out, which detected long CAG/CTG repeats in the affecteds, however the repeats were located on the normally expanded ERDA1 locus (Paper V). By genotyping a total of 695 microsatellite markers genome-widely a maximum lod score of 3.31 was obtained for D13S1265 at 0% recombination fraction, thus assigning the disease locus to 13q34 between D13S778 and D13SI315 with 5 cM distance. DNA sequencing of the coding regions of three candidate genes did not show any difference between affected patient and the control. (Paper VI)
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| 8. |
- Li, Wei, et al.
(författare)
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3-Aminopropanal, formed during cerebral ischaemia, is a potent lysosomotropic neurotoxin
- 2003
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Ingår i: Biochemical Journal. - 0264-6021 .- 1470-8728. ; 371:2, s. 429-436
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Tidskriftsartikel (refereegranskat)abstract
- Cytotoxic polyamine-derived amino aldehydes, formed during cerebral ischaemia, damage adjacent tissue (the so-called 'penumbra') not subject to the initial ischaemic insult. One such product is 3-aminopropanal (3-AP), a potent cytotoxin that accumulates in ischaemic brain, although the precise mechanisms responsible for its formation are still unclear. More relevant to the present investigations, the mechanisms by which such a small aldehydic compound might be cytotoxic are also not known, but we hypothesized that 3-AP, having the structure of a weak lysosomotropic base, might concentrate within lysosomes, making these organelles a probable focus of initial toxicity. Indeed, 3-AP leads to lysosomal rupture of D384 glioma cells, a process which clearly precedes caspase activation and apoptotic cell death. Immunohistochemistry reveals that 3-AP concentrates in the lysosomal compartment and prevention of this accumulation by the lysosomotropic base ammonia, NH3, protects against 3-AP cytotoxicity by increasing lysosomal pH. A thiol compound, N-(2-mercaptopropionyl)glycine, reacts with and neutralizes 3-AP and significantly inhibits cytoxocity. Both amino and aldehyde functions of 3-AP are necessary for toxicity: the amino group confers lysosomotropism and the aldehyde is important for additional, presently unknown, reactions. We conclude that 3-AP exerts its toxic effects by accumulating intralysosomally, causing rupture of these organelles and releasing lysosomal enzymes which initiate caspase activation and apoptosis (or necrosis if the lysosomal rupture is extensive). These results may have implications for the development of new therapeutics designed to lessen secondary damage arising from focal cerebral ischaemia.
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| 9. |
- Li, Wei, 1962-, et al.
(författare)
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Alpha-tocopherol and astaxanthin decrease macrophage infiltration, apoptosis and vulnerability in atheroma of hyperlipidaemic rabbits
- 2004
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Ingår i: Journal of Molecular and Cellular Cardiology. - : Elsevier BV. - 0022-2828 .- 1095-8584. ; 37:5, s. 969-978
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Tidskriftsartikel (refereegranskat)abstract
- The composition of atherosclerotic plaques, not just macroscopical lesion size, has been implicated in their susceptibility to rupture and the risk of thrombus formation. By focusing on the quality of lipids, macrophages, apoptosis, collagen, metalloproteinase expression and plaque integrity, we evaluated the possible anti-atherosclerotic effect of the antioxidants α-tocopherol and astaxanthin in Watanabe heritable hyperlipidemic (WHHL) rabbits. Thirty-one WHHL rabbits were divided into three groups and were fed a standard diet, as controls (N =10), or a standard diet with the addition of 500 mg α-tocopherol per kg feed (N =11) or 100 mg astaxanthin per kg feed (N =10) for 24 weeks. We found that both antioxidants, particularly astaxanthin, significantly decreased macrophage infiltration in the plaques although they did not affect lipid accumulation. All lesions in the astaxanthin-treated rabbits were classified as early plaques according to the distribution of collagen and smooth muscle cells. Both antioxidants also improved plaque stability and significantly diminished apoptosis, which mainly occurred in macrophages, matrix metalloproteinase three expressions and plaque ruptures. Although neither antioxidant altered the positive correlations between the lesion size and lipid accumulation, the lesion size and apoptosis were only positively correlated in the control group. Astaxanthin and α-tocopherol may improve plaque stability by decreasing macrophage infiltration and apoptosis in this atherosclerotic setting. Apoptosis reduction by α-tocopherol and astaxanthin may be a new anti-atherogenic property of these antioxidants. © 2004 Elsevier Ltd. All rights reserved.
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| 10. |
- Li, Wei, 1962-, et al.
(författare)
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Apoptotic Death of Inflammatory Cells in Human Atheroma
- 2001
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Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - : Ovid Technologies (Wolters Kluwer Health). - 1079-5642 .- 1524-4636. ; 21:7, s. 1124-1130
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Tidskriftsartikel (refereegranskat)abstract
- Although the accumulation of cholesterol and other lipidic material is unquestionably important in atherogenesis, the reasons why this material progressively accumulates, rather than being effectively cleared by phagocytic cells such as macrophages, are not completely understood. We hypothesize that atheromatous lesions may represent "death zones" that contain toxic materials such as oxysterols and in which monocytes/macrophages become dysfunctional and apoptotic. Indeed, cathepsins B and L, normally confined to the lysosomal compartment, are present in the cytoplasm and nuclei of apoptotic (caspase-3-positive) macrophages within human atheroma. The possible involvement of oxysterols is suggested by experiments in which cultured U937 and THP-1 cells exposed to 7-oxysterols similarly undergo marked lysosomal destabilization, caspase-3 activation, and apoptosis. Like macrophages within atheroma, intralysosomal cathepsins B and L are normally present in the cytoplasm and nuclei of these oxysterol-exposed cells. Lysosomal destabilization, cathepsin release, and apoptosis may be causally related, because inhibitors of cathepsins B and L suppress oxysterol-induced apoptosis. Thus, toxic materials such as 7-oxysterols in atheroma may impair the clearance of cholesterol and other lipidic material by fostering the apoptotic death of phagocytic cells, thereby contributing to further development of atherosclerotic lesions.
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