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Dalen, Helge
Publications (5 of 5) Show all publications
Hoem, D., Hostmark, J., Dalen, H. & Andren-Sandberg, A. (2008). Non-adhesive organ culture of human biliary epithelium with stroma. Scandinavian Journal of Gastroenterology, 43(4), 473-479.
Open this publication in new window or tab >>Non-adhesive organ culture of human biliary epithelium with stroma
2008 (English)In: Scandinavian Journal of Gastroenterology, ISSN 0036-5521, E-ISSN 1502-7708, Vol. 43, no 4, 473-479 p.Article in journal (Refereed) Published
Abstract [en]

Objective. Explanted tissue has been shown to keep adult human cells in organ culture with a preserved morphology for at least one month as spheres in a non-adhesive organ culture. In the present study, we explored whether also human biliary epithelium can be grown in this manner, because the result may be of interest in studies of hepato-biliary-pancreatic carciogenesis. Material and methods. Small tissue samples were obtained from the gallbladder wall of patients who had been operated upon with cholecystectomy. Fragments of about 300 µm in diameter from each patient were cultured and investigated with light microscopy at the time of explantation and after 5, 10, 20, 30 and 40 days of culture. Scanning and transmission electron microscopy were performed to demonstrate the ultrastructure. Incubation of cultured fragments with the vital dyes revealed a viable epithelium. Results. At the time of explantation, all the tissue fragments had a rough appearance with an uneven, torn periphery, while during the first few days of culture they became rounder with a smooth-looking surface covering the entire circumference. This spheroid morphology persisted for the remainder of the culture period. The core of the fragments harboured connective tissue with vascular elements, fibroblasts and leucocytes. Immunostaining for cytokeratin 7, 19 and 20 revealed a strong positive staining of the epithelium. Conclusions. These results show that biliary epithelium can be grown in vitro in a non-adhesive organ culture with their stroma. © 2008 Taylor & Francis.

Keyword
Biliary epithelium, Organ culture, Spheroide, Stroma
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-46455 (URN)10.1080/00365520701763373 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
Neuzil, J., Widen, C., Gellert, N., Swettenham, E., Zobalova, R., Dong, L.-F., . . . Witting, P. (2007). Mitochondria transmit apoptosis signalling in cardiomyocyte-like cells and isolated hearts exposed to experimental ischemia-reperfusion injury. Redox report, 12(3), 148-162.
Open this publication in new window or tab >>Mitochondria transmit apoptosis signalling in cardiomyocyte-like cells and isolated hearts exposed to experimental ischemia-reperfusion injury
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2007 (English)In: Redox report, ISSN 1351-0002, E-ISSN 1743-2928, Vol. 12, no 3, 148-162 p.Article in journal (Refereed) Published
Abstract [en]

Ischemia-reperfusion (I/R) is a condition leading to serious complications due to death of cardiac myocytes. We used the cardiomyocyte-like cell line H9c2 to study the mechanism underlying cell damage. Exposure of the cells to simulated I/R lead to their apoptosis. Over-expression of Bcl-2 and Bcl-xL protected the cells from apoptosis while over-expression of Bax sensitized them to programmed cell death induction. Mitochondria-targeted coenzyme Q (mitoQ) and superoxide dismutase both inhibited accumulation of reactive oxygen species (ROS) and apoptosis induction. Notably, mtDNA-deficient cells responded to I/R by decreased ROS generation and apoptosis. Using both in situ and in vivo approaches, it was found that apoptosis occurred during reperfusion following ischemia, and recovery was enhanced when hearts from mice were supplemented with mitoQ. In conclusion, I/R results in apoptosis in cultured cardiac myocytes and heart tissue largely via generation of mitochondria-derived superoxide, with ensuing apoptosis during the reperfusion phase. © W. S. Maney & Son Ltd.

Keyword
Apoptosis, Cardiomyocytes, Ischemia/reperfusion, Mitochondria, Superoxide
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-49610 (URN)10.1179/135100007X200227 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-12
Stroikin, Y., Dalen, H., Brunk, U. T. & Terman, A. (2005). Testing the “garbage” accumulation theory of ageing: mitotic activity protects cells from death induced by inhibition of autophagy. Biogerontology, 6(1), 39-47.
Open this publication in new window or tab >>Testing the “garbage” accumulation theory of ageing: mitotic activity protects cells from death induced by inhibition of autophagy
2005 (English)In: Biogerontology, ISSN 1389-5729, Vol. 6, no 1, 39-47 p.Article in journal (Refereed) Published
Abstract [en]

Imperfect autophagic degradation of oxidatively damaged macromolecules and organelles (so-called biological garbage) is considered an important contributor to ageing and consequent death of postmitotic (non-dividing) cells, such as neurons and cardiac myocytes. In contrast, proliferating cells apparently escape senescence by a continuous dilution and repair of damaged structures during division. Postmitotic ageing can be mimicked and studied in cultures of potentially dividing cells if their mitotic activity is inhibited. To test the garbage accumulation theory of ageing, we compared survival of density-dependent growth-arrested (confluent) and proliferating human fibroblasts and astrocytes following inhibition of autophagic sequestration with 3-methyladenine (3MA). Exposure of confluent fibroblast cultures to 3MA for two weeks resulted in a significantly increased proportion of dying cells compared to both untreated confluent cultures and dividing cells with 3MA-inhibited autophagy. Similar results were obtained when autophagic degradation was suppressed by the protease inhibitor leupeptin. In 3MA- or leupeptin-exposed cultures, dying cells were overloaded with undegraded autofluorescent material. The results support a key role of biological lysosomal garbage accumulation in the triggering of ageing and death of postmitotic cells, as well as the anti-ageing role of cell division.

Keyword
ageing, apoptosis, astrocytes, autophagocytosis, fibroblasts, 3-methyladenine, leupeptin, mitosis
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-14212 (URN)10.1007/s10522-004-7382-y (DOI)
Available from: 2007-01-09 Created: 2007-01-09 Last updated: 2009-06-04
Terman, A., Dalen, H., Eaton, J. W., Neuzil, J. & Brunka, U. (2004). Aging of cardiac myocytes in culture - Oxidative stress, lipofuscin accumulation, and mitochondrial turnover. Annals of the New York Academy of Sciences, 1019, 70-77.
Open this publication in new window or tab >>Aging of cardiac myocytes in culture - Oxidative stress, lipofuscin accumulation, and mitochondrial turnover
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2004 (English)In: Annals of the New York Academy of Sciences, ISSN 0077-8923, E-ISSN 1749-6632, Vol. 1019, 70-77 p.Article in journal (Refereed) Published
Abstract [en]

Oxidative stress is believed to be an important contributor to aging, mainly affecting long-lived postmitotic cells such as cardiac myocytes and neurons. Aging cells accumulate functionally effete, often mutant and enlarged mitochondria, as well as an intralysosomal undegradable pigment, lipofuscin. To provide better insight into the role of oxidative stress, mitochondrial damage, and lipofuscinogenesis in postmitotic aging, we studied the relationship between these parameters in cultured neonatal rat cardiac myocytes. It was found that the content of lipofuscin, which varied drastically between cells, positively correlated with mitochondrial damage (evaluated by decreased innermembrane potential), as well as with the production of reactive oxygen species. These results suggest that both lipofuscin accumulation and mitochondrial damage have common underlying mechanisms, likely including imperfect autophagy and ensuing lysosomal degradation of oxidatively damaged mitochondria and other organelles. Increased size of mitochondria (possibly resulting from impaired fission due to oxidative damage to mitochondrial DNA, membranes, and proteins) also may interfere with mitochondrial turnover, leading to the appearance of so-called "giant" mitochondria. This assumption is based on our observation that pharmacological inhibition of autophagy with 3-methyladenine induced only moderate accumulation of large (senescent-like) mitochondria but drastically increased numbers of small, apparently normal mitochondria, reflecting their rapid turnover and suggesting that enlarged mitochondria are poorly autophagocytosed. Overall, our findings emphasize the importance of mitochondrial turnover in postmitotic aging and provide further support for the mitochondrial-lysosomal axis theory of aging.

Keyword
aging, heart, lipofuscin, lysosomes, mitochondria, oxidative stress
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-46195 (URN)10.1196/annals.1297.015 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
Stroikin, Y., Dalen, H., Lööf, S. & Terman, A. (2004). Inhibition of autophagy with 3-methyladenine results in impaired turnover of lysosomes and accumulation of lipofuscin-like material. European journal of cell biology, 83(10), 583-590.
Open this publication in new window or tab >>Inhibition of autophagy with 3-methyladenine results in impaired turnover of lysosomes and accumulation of lipofuscin-like material
2004 (English)In: European journal of cell biology, ISSN 0171-9335, Vol. 83, no 10, 583-590 p.Article in journal (Refereed) Published
Abstract [en]

Autophagy (which includes macro-, micro-, and chaperone-mediated autophagy) is an important biological mechanism for degradation of damaged/obsolete macromolecules and organelles. Ageing non-dividing cells, however, progressively accumulate oxidised proteins, defective organelles and intralysosomal lipofuscin inclusions, suggesting inherent insufficiency of autophagy. To learn more about the role of macroautophagy in the turnover of organelles and lipofuscin formation, we inhibited autophagic sequestration with 3-methyladenine (3 MA) in growth-arrested human fibroblasts, a classical model of cellular ageing. Such treatment resulted in a dramatic accumulation of altered lysosomes, displaying lipofuscin-like autofluorescence, as well as in a moderate increase of mitochondria with lowered membrane potential. The size of the late endosomal compartment appeared not to be significantly altered following 3 MA exposure. The accumulation of lipofuscin-like material was enhanced when 3 MA administration was combined with hyperoxia. The findings suggest that macroautophagy is essential for normal turnover of lysosomes. This notion is supported by reports in the literature of lysosomal membrane proteins inside lysosomes and/or late endosomes, as well as lysosomes with active hydrolases within autophagosomes following vinblastine-induced block of fusion between lysosomes and autophagosomes. The data also suggest that specific components of lysosomes, such as membranes and proteins, may be direct sources of lipofuscin.

Keyword
Ageing, Autophagocytosis, Fibroblasts, Lysosomes, 3-Methyladenine
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-14211 (URN)10.1078/0171-9335-00433 (DOI)
Available from: 2007-01-09 Created: 2007-01-09 Last updated: 2009-06-04
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