| 1. |
- Nayeri, Fariba, et al.
(författare)
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An in vitro model for assessment of the biological activity of hepatocyte growth factor
- 2007
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Ingår i: Growth Factors. - : Informa UK Limited. - 0897-7194 .- 1029-2292. ; 25:1, s. 33-40
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Tidskriftsartikel (refereegranskat)abstract
- Hepatocyte growth factor (HGF) is a multifunctional growth factor with potent wound-healing properties that functions in the healing of chronic injuries. However, there may be a loss of HGF activity in certain chronic cases; this might be indicated by the presence of high amounts of HGF in body fluids and by the elevated expression of the HGF receptor in tissue biopsies. In such cases, a reliable means of assessing the activity of endogenous HGF would be valuable in allowing clinicians to decide if treatment with HGF would be useful. In this study, we developed an in vitro wound assay that used a mouse skin epithelial cell line to evaluate the biological activity of HGF. We showed that HGF accelerated the motility of the epithelial cells in a dose-dependent fashion with high sensitivity and specificity. This in vitro assay might be used to determine the activity of both endogenous and recombinant HGF.
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| 2. |
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| 3. |
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| 4. |
- Gréen,, Anna, 1973-, et al.
(författare)
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Translocation of Histone H1 Subtypes Between Chromatin and Cytoplasm During Mitosis in Normal Human Fibroblasts
- 2010
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Ingår i: Cytometry Part A. - : John Wiley & Sons. - 1552-4922 .- 1552-4930. ; 77A:5, s. 478-484
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Tidskriftsartikel (refereegranskat)abstract
- Histone H1 is an important constituent of chromatin which undergoes major structural rearrangements during mitosis. However, the role of H1, multiple H1 subtypes and H1 phosphorylation is still unclear. In normal human fibroblasts, phosphorylated H1 was found located in nuclei during prophase and in both cytoplasm and condensed chromosomes during metaphase, anaphase and telophase as detected by immunocytochemistry. Moreover, we detected remarkable differences in the distribution of the histone H1 subtypes H1.2, H1.3 and H1.5 during mitosis. H1.2 was found in chromatin during prophase, and almost solely in the cytoplasm of metaphase and early anaphase cells. In late anaphase it appeared in both chromatin and cytoplasm, and again in chromatin during telophase. H1.5 distribution pattern resembled that of H1.2, but some H1.5 remained situated in chromatin during metaphase and early anaphase. H1.3 was detected in chromatin in all cell cycle phases. We propose therefore, that H1 subtype translocation during mitosis is controlled by phosphorylation, in combination with H1 subtype inherent affinity. We conclude that H1 subtypes, or their phosphorylated variants, may be signalling molecules in mitosis or that they leave chromatin in a regulated way to give access for chromatin condensing factors or transcriptional regulators during mitosis.
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| 5. |
- Gustavsson, Johanna, 1956-, et al.
(författare)
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Localization of the insulin receptor in caveolae of adipocyte plasma membrane
- 1999
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Ingår i: The FASEB Journal. - 0892-6638 .- 1530-6860. ; 13:14, s. 1961-1971
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Tidskriftsartikel (refereegranskat)abstract
- The insulin receptor is a transmembrane protein of the plasma membrane, where it recognizes extracellular insulin and transmits signals into the cellular signaling network. We report that insulin receptors are localized and signal in caveolae microdomains of adipocyte plasma membrane. Immunogold electron microscopy and immunofluorescence microscopy show that insulin receptors are restricted to caveolae and are colocalized with caveolin over the plasma membrane. Insulin receptor was enriched in a caveolae-enriched fraction of plasma membrane. By extraction with β-cyclodextrin or destruction with cholesterol oxidase, cholesterol reduction attenuated insulin receptor signaling to protein phosphorylation or glucose transport. Insulin signaling was regained by spontaneous recovery or by exogenous replenishment of cholesterol. β-Cyclodextrin treatment caused a nearly complete annihilation of caveolae invaginations as examined by electron microscopy. This suggests that the receptor is dependent on the caveolae environment for signaling. Insulin stimulation of cells prior to isolation of caveolae or insulin stimulation of the isolated caveolae fraction increased tyrosine phosphorylation of the insulin receptor in caveolae, demonstrating that insulin receptors in caveolae are functional. Our results indicate that insulin receptors are localized to caveolae in the plasma membrane of adipocytes, are signaling in caveolae, and are dependent on caveolae for signaling.
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| 6. |
- Hollén, Elisabet, et al.
(författare)
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Coeliac children on a gluten-free diet with or without oats display equal anti-avenin antibody titres
- 2006
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 41:1, s. 42-47
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Recent studies report negligible toxicity of oats in the majority of coeliac disease (CD) patients. It has previously been shown that children with untreated CD have circulating antibodies to oats avenin. In this study we performed serial assessments of anti-avenin antibodies in children under investigation for CD on a gluten-free diet with or without oats. Material and methods. The study involved 116 children, randomized to a standard gluten-free diet or a gluten-free diet supplemented with oats. Sera were obtained from 86 children, 48 in the standard gluten-free group and 38 in the gluten-free oats group, of which 33 consumed at least 10 g of oats daily. IgA and IgG anti-avenin antibodies were monitored at 0, 3, 6 and 12 months. Nitric oxide metabolites were measured in 7 patients, with deviating antibody results. Results. There was a significant decrease in anti-avenin antibodies in both groups at the end as compared to the beginning of the study, (p<0.001), but no difference was found between the two groups. IgA titres already declined after 3 months. IgG titres, although significantly decreased, remained high in the majority of patients in both groups. Nitric oxide levels were high in four of the analysed samples. Conclusions. Oats per se, do not seem to produce a humoral immune reaction in children with CD when given in an otherwise gluten-free diet, indicating that the reaction requires gluten challenge. Anti-avenin antibodies were equal in the two study groups, and these findings strengthen the clinical impression that oats can be tolerated by the majority of patients with CD.
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| 7. |
- Holmgren-Peterson, Kajsa, 1964-
(författare)
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Structure and dynamics of epithelial cells : Studied with confocal microscopy and flourescence recovery after photobleaching
- 1995
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Epithelial cells of the human body form a physical barrier to harmful agents and potential invading microorganisms. In the small intestine they must also produce enzymes for digestion of food and be able to absorb nutrients.The aim of this work was to study properties of epithelial cells in model systems using cell lines and toad bladder cells, and to study the effect of gluten intolerance (celiac disease, CD), viz. a pathological condition, on human small-intestine epithelial cells, enterocytes. Fluores-cence microscopy techniques, and primarily confocallaser scanning microscopy (CLSM), have beeen used as the major methods in the investigation. Part of the work has also been to develop, and apply, tools for measurements in confocal rnicroscopy images to obtain semi-quantitative information on structures.Fluorescence recovery after photobleaching (FRAP) was used to study the effect of maturation of small intestine-like epithelial cells. Lateral diffusion of membrane components was measured to reveal alterations in membrane fluidity induced by differentiation. No general effects on the lateral mobility of membrane components was observed, rather distinct effects were noticed on protein diffusion.Vasopressin induces the fusion of vesicles containing water channels with the apical membrane of toad bladder epithelial cells. This fusion is known to result in depolymerization of fllamentous actin (F-actin) of the cell. CLSM was used to assess where in the cell the depolymerization occurs. It was demonstrated that the depolymerization is not evenly distributed, but confined only to the apical region of the cells.In children suffering from celiac disease the mucosa of the small intestine is severely damaged. The damage at the enterocyte level is, however, less investigated. In the present work, CLSM was applied to compare the distributions ofF-actin and of glycoconjugates in enterocytes from children with CD to enterocytes from children not suffering from the disease. The results show that in children with active CD the distribution of both structures was altered, but also that compliance to a gluten-free diet results in the return to normal-looking enterocytes.
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| 8. |
- Immerstrand, Charlotte, et al.
(författare)
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Conjugated-polymer micro- and milliactuators for biological applications
- 2002
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Ingår i: MRS bulletin. - : Springer Science and Business Media LLC. - 0883-7694 .- 1938-1425. ; 27:6, s. 461-464
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Tidskriftsartikel (refereegranskat)abstract
- The development of new conjugated-polymer tools for the study of the biological realm, and for use in a clinical setting, is reviewed in this article. Conjugated-polymer actuators, based on the changes of volume of the active conjugated polymer during redox transformation, can be used in electrolytes employed in cell-culture media and in biological fluids such as blood, plasma, and urine. Actuators ranging in size from 10 μm to 100 μm suitable for building structures to manipulate single cells are produced with photolithographic techniques. Larger actuators may be used for the manipulation of blood vessels and biological tissue.
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| 9. |
- Immerstrand, Charlotte, 1974-, et al.
(författare)
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Height changes associated with pigment aggregation in Xenopus laevis melanophores
- 2004
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Ingår i: Bioscience Reports. - : Portland Press Ltd.. - 0144-8463 .- 1573-4935. ; 24:3, s. 203-214
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Tidskriftsartikel (refereegranskat)abstract
- Melanophores are pigment cells found in the skin of lower vertebrates. The brownish-black pigment melanin is stored in organelles called melanosomes. In response to different stimuli, the cells can redistribute the melanosomes, and thereby change colour. During melanosome aggregation, a height increase has been observed in fish and frog melanophores across the cell centre. The mechanism by which the cell increases its height is unknown. Changes in cell shape can alter the electrical properties of the cell, and thereby be detected in impedance measurements. We have in earlier studies of Xenopus laevis melanophores shown that pigment aggregation can be revealed as impedance changes, and therefore we were interested in investigating the height changes associated with pigment aggregation further. Accordingly, we quantified the changes in cell height by performing vertical sectioning with confocal microscopy. In analogy with theories explaining the leading edge of migrating cells, we investigated the possibility that the elevation of plasma membrane is caused by local swelling due to influx of water through HgC12-sensitive aquaporins. We also measured the height of the microtubule structures to assess whether they are involved in the height increase. Our results show that pigment aggregation in X. laevis melanophores resulted in a significant height increase, which was substantially larger when aggregation was induced by latrunculin than with melatonin. Moreover, the elevation of the plasma membrane did not correlate with influx of water through aquaporins or formation of new microtubules, Rather, the accumulation of granules seemed to drive the change in cell height.
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| 10. |
- Immerstrand, Charlotte, et al.
(författare)
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Image correlation spectroscopy for quantification of pigment aggregation
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In the skin of amphibia, fish, and other organisms, the distribution of the pigment granules within melanophores regulates skin colour. In this study we have applied Image Correlation Spectroscopy (ICS; Petersen et al. 1998; Petersen et al. 1993) to monitor the aggregation of pigment granules. Normally in ICS, images from confocallaser scanning rnicroscopy are used to calculate autocorrelation functions from which the density of fluorescent particles in the image, like membrane receptors, can be obtained. The present study differs from traditional ICS in that the images are obtained by light microscopy and then Gaussian filtered to give the particles the appropriate intensity profile required for ICS analysis. ICS appears to be more sensitive than particle counting and image mean intensity for quantification of the degree of pigment aggregation. This study demonstrates for the first time that ICS can be used to analyse the aggregation of non-fluorescent particles, such as pigment granules in Xenopus laevis melanophores.
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