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Sökning: WFRF:(Alanentalo Tomas)

  • Resultat 1-10 av 12
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1.
  • Hahn, Max, et al. (författare)
  • Topologically selective islet vulnerability and self-sustained downregulation of markers for β-cell maturity in streptozotocin-induced diabetes
  • 2020
  • Ingår i: Communications Biology. - : Nature Publishing Group. - 2399-3642. ; 3:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Mouse models of Streptozotocin (STZ) induced diabetes represent the most widely used preclinical diabetes research systems. We applied state of the art optical imaging schemes, spanning from single islet resolution to the whole organ, providing a first longitudinal, 3D-spatial and quantitative account of β-cell mass (BCM) dynamics and islet longevity in STZ-treated mice. We demonstrate that STZ-induced β-cell destruction predominantly affects large islets in the pancreatic core. Further, we show that hyperglycemic STZ-treated mice still harbor a large pool of remaining β-cells but display pancreas-wide downregulation of glucose transporter type 2 (GLUT2). Islet gene expression studies confirmed this downregulation and revealed impaired β-cell maturity. Reversing hyperglycemia by islet transplantation partially restored the expression of markers for islet function, but not BCM. Jointly our results indicate that STZ-induced hyperglycemia results from β-cell dysfunction rather than β-cell ablation and that hyperglycemia in itself sustains a negative feedback loop restraining islet function recovery.
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  • Alanentalo, Tomas, et al. (författare)
  • High-resolution three-dimensional imaging of islet-infiltrate interactions based on optical projection tomography assessments of the intact adult mouse pancreas
  • 2008
  • Ingår i: Journal of Biomedical Optics. - Bellingham, WA : SPIE--the International Society for Optical Engineering. - 1083-3668 .- 1560-2281. ; 13:5, s. 054070-
  • Tidskriftsartikel (refereegranskat)abstract
    • A predicament when assessing the mechanisms underlying the pathogenesis of type-1 diabetes (T1D) has been to maintain simultaneous global and regional information on the loss of insulin-cell mass and the progression of insulitis. We present a procedure for high-resolution 3-D analyses of regions of interest (ROIs), defined on the basis of global assessments of the 3-D distribution, size, and shape of molecularly labeled structures within the full volume of the intact mouse pancreas. We apply a refined protocol for optical projection tomography (OPT)-aided whole pancreas imaging in combination with confocal laser scanning microscopy of site-directed pancreatic microbiopsies. As such, the methodology provides a useful tool for detailed cellular and molecular assessments of the autoimmune insulitis in T1D. It is anticipated that the same approach could be applied to other areas of research where 3-D molecular distributions of both global and regional character is required.
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4.
  • Alanentalo, Tomas, et al. (författare)
  • Mesoscopic Optical Imaging of the Pancreas : Revisiting Pancreatic Anatomy and Pathophysiology
  • 2021
  • Ingår i: Frontiers in Endocrinology. - : Frontiers Media S.A.. - 1664-2392 .- 1664-2392. ; 12
  • Forskningsöversikt (refereegranskat)abstract
    • The exocrine-endocrine multipart organization of the pancreas makes it an exceedingly challenging organ to analyze, quantitatively and spatially. Both in rodents and humans, estimates of the pancreatic cellular composition, including beta-cell mass, has been largely relying on the extrapolation of 2D stereological data originating from limited sample volumes. Alternatively, they have been obtained by low resolution non-invasive imaging techniques providing little detail regarding the anatomical organization of the pancreas and its cellular and/or molecular make up. In this mini-review, the state of the art and the future potential of currently existing and emerging high-resolution optical imaging techniques working in the mm-cm range with μm resolution, here referred to as mesoscopic imaging approaches, will be discussed regarding their contribution toward a better understanding of pancreatic anatomy both in normal conditions and in the diabetic setting. In particular, optical projection tomography (OPT) and light sheet fluorescence microscopy (LSFM) imaging of the pancreas and their associated tissue processing and computational analysis protocols will be discussed in the light of their current capabilities and future potential to obtain more detailed 3D-spatial, quantitative, and molecular information of the pancreas.
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5.
  • Alanentalo, Tomas, 1978- (författare)
  • Optical projection tomography based 3D-spatial and quantitative assessments of the diabetic pancreas
  • 2008
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • The gastrointestinal tract comprises a number of digestive organs including the stomach and pancreas. The stomach is involved in the digestion and short term storage of food while the pancreas is a mixed endocrine and exocrine gland which provides the body with hormones and enzymes essential for nutritional utilisation. The pancreas consists of three different cell lineages, acinar, ductal and endocrine cells. The endocrine cells, organised in the islets of Langerhans, are scattered throughout the exocrine parenchyma and regulate blood glucose levels by production of hormones such as glucagon and insulin. The Nkx family of homeodomain proteins controls numerous processes during development. Previous studies have identified two members belonging to the Nkx6 subfamily of Nkx proteins, Nkx6.1 and Nkx6.2. We have described the cloning and embryonic expression pattern of Nkx6.3. All three members of the Nkx6 gene family were shown to be expressed in partially overlapping domains during the development of the gastrointestinal tract and the central nervous system. Nkx6.2 was also identified as a transient marker for pancreatic exocrine cells. Analysing gene expression patterns and morphological features in tissues and organs is often performed by stereologic sampling which is a labour-intensive two dimensional approach that rely on certain assumptions when calculating e.g. β-cell mass and islet number in the pancreas. By combined improvements in immunohistochemical protocols, computational processing and tomographic scanning, we have developed a methodology based on optical projection tomography (OPT) allowing for 3D visualisation and quantification of specifically labelled objects within intact adult mouse organs. In the pancreas, this technique allows for spatial and quantitative measurements of total islet number and β-cell mass. We have further developed a protocol allowing for high resolution regional analyses based on global OPT assessments of the pancreatic constitution. This methodology is likely to facilitate detailed cellular and molecular analysis of user defined regions of interest in the pancreas, at the same time providing information on the overall disease state of the gland. Type 1 diabetes mellitus (T1D) can occur at any age and is characterized by the marked inability of the pancreas to secrete insulin due to an autoimmune destruction of the insulin producing β-cells. Information on the key cellular and molecular events underlying the recruitment of lymphocytes, their infiltration of the islets of Langerhans and consequent β-cell destruction is essential for understanding the pathogenesis of T1D. Using the developed methodology we have recorded the spatial and quantitative distribution of islet β-cells and infiltrating lymphocytes in the non obese diabetic (NOD) mouse model for T1D. This study shows that the smaller islets, which are predominantly organised in the periphery of the organ, are the first to disappear during the progression of T1D. The larger islets appear more resistant and our data suggest that a compensatory proliferative process is going on side by side with the autoimmune-induced β-cell destruction. Further, the formation of structures resembling tertiary lymphoid organs (TLOs) in areas apparently unaffected by insulitis suggests that local factors may provide cues for the homing of these lymphocytes back to the pancreas.
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6.
  • Alanentalo, Tomas, et al. (författare)
  • Quantification and 3-D imaging of the insulitis-induced destruction of β-cells in murine type 1 diabetes
  • 2010
  • Ingår i: Diabetes. - 0012-1797 .- 1939-327X. ; 59:7, s. 1756-1764
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: The aim of this study was to refine the information regarding the quantitative and spatial dynamics of infiltrating lymphocytes and remaining beta-cell volume during the progression of type 1 diabetes in the NOD mouse model of the disease.Research design and methods: Using an ex vivo technique, optical projection tomography (OPT), we quantified and assessed the 3D spatial development and progression of insulitis and beta-cell destruction in pancreas from diabetes prone NOD and non-diabetes prone congenic NOD.H-2b mice between 3 and 16 weeks of age.Results: Together with results showing the spatial dynamics of the insulitis process we provide data of beta-cell volume distributions down to the level of the individual islets and throughout the pancreas during the development and progression of type 1 diabetes. Our data provide evidence for a compensatory growth potential of the larger insulin(+) islets during the later stages of the disease around the time point for development of clinical diabetes. This is in contrast to smaller islets, which appear less resistant to the autoimmune attack. We also provide new information on the spatial dynamics of the insulitis process itself, including its apparently random distribution at onset, the local variations during its further development, and the formation of structures resembling tertiary lymphoid organs at later phases of insulitis progression.Conclusions: Our data provides a powerful tool for phenotypic analysis of genetic and environmental effects on type 1 diabetes etiology as well as for evaluating the potential effect of therapeutic regimes.
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  • Eriksson, Anna U., et al. (författare)
  • Near infrared optical projection tomography for assessments of beta-cell mass distribution in diabetes research
  • 2013
  • Ingår i: Journal of Visualized Experiments. - 1940-087X .- 1940-087X. ; 71
  • Tidskriftsartikel (refereegranskat)abstract
    • By adapting OPT to include the capability of imaging in the near infrared (NIR) spectrum, we here illustrate the possibility to image larger bodies of pancreatic tissue, such as the rat pancreas, and to increase the number of channels (cell types) that may be studied in a single specimen. We further describe the implementation of a number of computational tools that provide: 1/ accurate positioning of a specimen's (in our case the pancreas) centre of mass (COM) at the axis of rotation (AR)2; 2/ improved algorithms for post-alignment tuning which prevents geometric distortions during the tomographic reconstruction2 and 3/ a protocol for intensity equalization to increase signal to noise ratios in OPT-based BCM determinations3. In addition, we describe a sample holder that minimizes the risk for unintentional movements of the specimen during image acquisition. Together, these protocols enable assessments of BCM distribution and other features, to be performed throughout the volume of intact pancreata or other organs (e.g. in studies of islet transplantation), with a resolution down to the level of individual islets of Langerhans.
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10.
  • Hahn, Max, et al. (författare)
  • Mesoscopic 3D imaging of pancreatic cancer and Langerhans islets based on tissue autofluorescence
  • 2020
  • Ingår i: Scientific Reports. - : NATURE RESEARCH. - 2045-2322. ; 10
  • Tidskriftsartikel (refereegranskat)abstract
    • The possibility to assess pancreatic anatomy with microscopic resolution in three dimensions (3D) would significantly add to pathological analyses of disease processes. Pancreatic ductal adenocarcinoma (PDAC) has a bleak prognosis with over 90% of the patients dying within 5 years after diagnosis. Cure can be achieved by surgical resection, but the efficiency remains drearily low. Here we demonstrate a method that without prior immunohistochemical labelling provides insight into the 3D microenvironment and spread of PDAC and premalignant cysts in intact surgical biopsies. The method is based solely on the autofluorescent properties of the investigated tissues using optical projection tomography and/or light-sheet fluorescence microscopy. It does not interfere with subsequent histopathological analysis and may facilitate identification of tumor-free resection margins within hours. We further demonstrate how the developed approach can be used to assess individual volumes and numbers of the islets of Langerhans in unprecedently large biopsies of human pancreatic tissue, thus providing a new means by which remaining islet mass may be assessed in settings of diabetes. Generally, the method may provide a fast approach to provide new anatomical insight into pancreatic pathophysiology.
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  • Resultat 1-10 av 12
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