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Sökning: WFRF:(Holm Lena 1951 )

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  • Holm, Lena, 1951- (författare)
  • The use of stone and hunting of reindeer a study of stone tool manufacture and hunting of large mammals in the central Scandes c. 6000-1 BC
  • 1991
  • Ingår i: digitalisering@umu. - Umeå : Umeå universitet. - 91-7174-634-X
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • <p>The thesis raises questions concerning prehistoric conditions in a high mountain region in central Scandinavia; it focuses on the human use of stone and on hunting principally of reindeer. An analysis of how the stone material was utilized and an approach to how large mammals were hunted result in a synthesis describing one interpretation of how the vast landscape of a region in the central Scandinavian high mountains was used. With this major aim as a base questions were posed concerning the human use of stone resources and possible changes in this use. Preconditions for the occurrence of large mammals as game animals and for hunting are also highlighted. A general perspective is the long time period over which possible changes in the use of stone and hunting of big game, encompassing the Late Mesolithic, Neolithic, Bronze Age and to a certain extent the Early Iron Age.</p><p>Considering the manufacture of flaked stone tools, debitage in the form of flakes from a dwelling, constitute the base where procurement and technology are essential. The occupation of the dwelling covers a period from the Late Mesolithic to the Bronze Age. Possible changes in lithic use are discussed based on an analysis of debitage which includes testing variables reflecting various steps in the process of flaked stone tool manufacture. Also, the results are discussed from a methodological aspect; the classificatory aspect of analyzing large flake assemblages is implied. The result of the flake analysis indicates differences in the use of stone from the Late Mesolithic to the Bronze Age/Early Iron Age. These differences are interpreted in a three-part chronological division and as theoretically proceeding in a manufacturing process of five steps including acquisition, reduction through three steps and use of completed tools. A pattern, dividing the Bronze Age use of stone from that of the Neolithic and Late Mesolithic is discerned and discussed in terms of changes in procurement strategies and technology. Also, social organization is touched upon.</p><p>When approaching the issue of hunting the character of data differ; archaeological and palaeo-environmental data together comprise the base for a discussion of possible changes. This is based on a theoretical model applied in a hypothetical research design. Archaeological categories of remains relevant in hunting contexts together with ethnographic and traditional hunting techniques are discussed. They constitute the base and illustrate possible variables in the testing of the hypothetical model. Changes in the Holocene climate are clear, just as changes in the archaeological record are observable. Together these circumstances indicate changes in the hunting process.</p><p>The structural changes in economy and society that occur in central and north Scandinavia during stone-using periods are discernible in the region studied here.</p>
  • Johansson, Malin E V, 1971-, et al. (författare)
  • Bacteria penetrate the inner mucus layer before inflammation in the dextran sulfate colitis model.
  • 2010
  • Ingår i: PloS one. - 1932-6203. ; 5:8
  • Tidskriftsartikel (refereegranskat)abstract
    • Protection of the large intestine with its enormous amount of commensal bacteria is a challenge that became easier to understand when we recently could describe that colon has an inner attached mucus layer devoid of bacteria (Johansson et al. (2008) Proc. Natl. Acad. Sci. USA 105, 15064-15069). The bacteria are thus kept at a distance from the epithelial cells and lack of this layer, as in Muc2-null mice, allow bacteria to contact the epithelium. This causes colitis and later on colon cancer, similar to the human disease Ulcerative Colitis, a disease that still lacks a pathogenetic explanation. Dextran Sulfate (DSS) in the drinking water is the most widely used animal model for experimental colitis. In this model, the inflammation is observed after 3-5 days, but early events explaining why DSS causes this has not been described.
  • Johansson, Malin E V, 1971-, et al. (författare)
  • The inner of the two Muc2 mucin-dependent mucus layers in colon is devoid of bacteria.
  • 2008
  • Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 1091-6490. ; 105:39, s. 15064-9
  • Tidskriftsartikel (refereegranskat)abstract
    • We normally live in symbiosis with approximately 10(13) bacteria present in the colon. Among the several mechanisms maintaining the bacteria/host balance, there is limited understanding of the structure, function, and properties of intestinal mucus. We now demonstrate that the mouse colonic mucus consists of two layers extending 150 mum above the epithelial cells. Proteomics revealed that both of these layers have similar protein composition, with the large gel-forming mucin Muc2 as the major structural component. The inner layer is densely packed, firmly attached to the epithelium, and devoid of bacteria. In contrast, the outer layer is movable, has an expanded volume due to proteolytic cleavages of the Muc2 mucin, and is colonized by bacteria. Muc2(-/-) mice have bacteria in direct contact with the epithelial cells and far down in the crypts, explaining the inflammation and cancer development observed in these animals. These findings show that the Muc2 mucin can build a mucus barrier that separates bacteria from the colon epithelia and suggest that defects in this mucus can cause colon inflammation.
  • Malmberg, Emily, 1978-, et al. (författare)
  • Increased levels of mucins in the cystic fibrosis mouse small intestine, and modulator effects of the Muc1 mucin expression.
  • 2006
  • Ingår i: American journal of physiology. Gastrointestinal and liver physiology. - 0193-1857. ; 291:2, s. G203-10
  • Tidskriftsartikel (refereegranskat)abstract
    • The mouse model (Cftr(tm1UNC)/Cftr(tm1UNC)) for cystic fibrosis (CF) shows mucus accumulation and increased Muc1 mucin mRNA levels due to altered splicing (Hinojosa-Kurtzberg AM, Johansson MEV, Madsen CS, Hansson GC, and Gendler SJ. Am J Physiol Gastrointest Liver Physiol 284: G853-G862, 2003). However, it is not known whether Muc1 is a major mucin contributing to the increased mucus and why CF/Muc1-/- mice show lower mucus accumulation. To address this, we have purified mucins from the small intestine of CF mice using guanidinium chloride extraction, ultracentrifugation, and gel filtration and analyzed them by slot blot, gel electrophoresis, proteomics, and immunoblotting. Normal and CF mice with wild-type (WT) Muc1 or Muc1-/- or that are transgenic for human MUC1 (MUC1.Tg, on a Muc1-/- background) were analyzed. The total amount of mucins, both soluble and insoluble in guanidinium chloride, increased up to 10-fold in the CF mice compared with non-CF animals, whereas the CF mice lacking Muc1 showed intermediate levels between the CF and non-CF mice. However, the levels of Muc3 (orthologue of human MUC17) were increased in the CF/Muc1-/- mice compared with the CF/MUC1.Tg animals. The amount of MUC1 mucin was increased several magnitudes in the CF mice, but MUC1 did still not appear to be a major mucin. The amount of insoluble mucus of the large intestine was also increased in the CF mice, an effect that was partially restored in the CF/Muc1-/- mice. The thickness of the firmly adherent mucus layer of colon in the Muc1-/- mice was significantly lower than that of WT mice. The results suggest that MUC1 is not a major component in the accumulated mucus of CF mice and that MUC1 can influence the amount of other mucins in a still unknown way.
  • Phillipson, Mia, et al. (författare)
  • The gastric mucus layers: constituents and regulation of accumulation.
  • 2008
  • Ingår i: American journal of physiology. Gastrointestinal and liver physiology. - 0193-1857. ; 295:4, s. G806-12
  • Tidskriftsartikel (refereegranskat)abstract
    • The mucus layer continuously covering the gastric mucosa consists of a loosely adherent layer that can be easily removed by suction, leaving a firmly adherent mucus layer attached to the epithelium. These two layers exhibit different gastroprotective roles; therefore, individual regulation of thickness and mucin composition were studied. Mucus thickness was measured in vivo with micropipettes in anesthetized mice [isoflurane; C57BL/6, Muc1-/-, inducible nitric oxide synthase (iNOS)-/-, and neuronal NOS (nNOS)-/-] and rats (inactin) after surgical exposure of the gastric mucosa. The two mucus layers covering the gastric mucosa were differently regulated. Luminal administration of PGE(2) increased the thickness of both layers, whereas luminal NO stimulated only firmly adherent mucus accumulation. A new gastroprotective role for iNOS was indicated since iNOS-deficient mice had thinner firmly adherent mucus layers and a lower mucus accumulation rate, whereas nNOS did not appear to be involved in mucus secretion. Downregulation of gastric mucus accumulation was observed in Muc1-/- mice. Both the firmly and loosely adherent mucus layers consisted of Muc5ac mucins. In conclusion, this study showed that, even though both the two mucus layers covering the gastric mucosa consist of Muc5ac, they are differently regulated by luminal PGE(2) and NO. A new gastroprotective role for iNOS was indicated since iNOS-/- mice had a thinner firmly adherent mucus layer. In addition, a regulatory role of Muc1 was demonstrated since downregulation of gastric mucus accumulation was observed in Muc1-/- mice.
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