| 1. |
- Sodergren, Erica, et al.
(författare)
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The genome of the sea urchin Strongylocentrotus purpuratus.
- 2006
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 314:5801, s. 941-52
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Tidskriftsartikel (refereegranskat)abstract
- We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotus purpuratus, a model for developmental and systems biology. The sequencing strategy combined whole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones, aided by a pooling strategy, overcame difficulties associated with high heterozygosity of the genome. The genome encodes about 23,300 genes, including many previously thought to be vertebrate innovations or known only outside the deuterostomes. This echinoderm genome provides an evolutionary outgroup for the chordates and yields insights into the evolution of deuterostomes.
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| 2. |
- Brandhorst, Heide, et al.
(författare)
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Large-Scale Comparison of Liberase HI and Collagenase NB1 Utilized for Human Islet Isolation
- 2010
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Ingår i: Cell Transplantation. - 0963-6897 .- 1555-3892. ; 19:1, s. 3-8
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Tidskriftsartikel (refereegranskat)abstract
- For more than a decade Liberase HI was commonly used as the standard enzyme blend for clinical human islet isolation until enforced replacement by collagenase NB1 (NB1). This change resulted initially in a reduction in islet isolation outcome and transplant activities worldwide. This retrospective study was initiated to compare the efficiency of NB1 premium grade with Liberase in 197 human islet isolations. All pancreata were processed between January 2006 and June 2008 utilizing the same procedures for isolation and quality assessment except the administration of preselected lots of either Liberase (n = 101) or NB1 (n = 96). Utilizing Liberase significantly more digested tissue and purified islet yield was produced compared to NB1. In contrast, the use of NB1 was associated with significantly higher purity and glucose stimulation index during dynamic perifusion. The expression of proinflammatory markers was almost identical except tissue factor expression that was higher after utilization of Liberase. No difference was found in the percentage of pancreata fulfilling the criteria for clinical islet transplantation. The results suggest that Liberase is more efficient for pancreas dissociation than collagenase NB1 but seems to be more harmful to exocrine cells and islet tissue.
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| 3. |
- Bennet, W, et al.
(författare)
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Incompatibility between human blood and isolated islets of Langerhans: a finding with implications for clinical intraportal islet transplantation?
- 1999
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 48:10, s. 1907-1914
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Tidskriftsartikel (refereegranskat)abstract
- The remarkable difference in success rates between clinical pancreas transplantation and islet transplantation is poorly understood. Despite the same histocompatibility barrier and similar immunosuppressive treatments in both transplantation procedures, human intraportal islet transplantation has a much inferior success rate than does vascularized pancreas transplantation. Thus far, little attention has been directed to the possibility that islets transplanted into the blood stream may elicit an injurious incompatibility reaction. We have tested this hypothesis in vitro with human islets and in vivo with porcine islets. Human islets were exposed to nonanticoagulated human ABO-compatible blood in surface-heparinized polyvinyl chloride tubing loops. Heparin and/or the soluble complement receptor 1 (sCR1) TP10 were tested as additives. Adult porcine islets were transplanted intraportally into pigs, and the liver was recovered after 60 min for immunohistochemical staining. Human islets induced a rapid consumption and activation of platelets. Neutrophils and monocytes were also consumed, and the coagulation and complement systems were activated. Upon histological examination, islets were found to be embedded in clots and infiltrated with CD11+ leukocytes. Furthermore, the cellular morphology was disrupted. When heparin and sCR1 were added to the blood, these events were avoided. Porcine islets retrieved in liver biopsies after intraportal islet allotransplantation showed a morphology similar to that of human islets perifused in vitro. Thus, exposure of isolated islets of Langerhans to allogenic blood resulted in significant damage to the islets, a finding that could explain the unsatisfactory clinical results obtained with intraportal islet transplantation. Because administration of heparin in combination with a soluble complement receptor abrogated these events, such treatment would presumably improve the outcome of clinical islet transplantation by reducing both initial islet loss and subsequent specific immune responses.
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| 4. |
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| 5. |
- Brandhorst, Heide, 1962-, et al.
(författare)
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A new oxygen carrier for improved long-term storage of human pancreata before islet isolation
- 2010
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Ingår i: Transplantation. - 0041-1337 .- 1534-6080. ; 89:2, s. 155-60
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Pancreas oxygenation during cold storage has been established in islet isolation and transplantation to prevent ischemic tissue damage using perfluorodecalin (PFD) as hyperoxygen carrier. However, studies in humans and pigs provided conflicting results about the efficiency of PFD for pancreas oxygenation. The aim of this study was to compare PFD with a newly developed oxygen carrier composed of perfluorohexyloctane and polydimethylsiloxane 5 (F6H8S5) for long-term storage of human pancreata.METHODS: After 24-hr storage in preoxygenated PFD or F6H8S5, pancreata were processed using Liberase HI for pancreas dissociation and a Ficoll gradient for islet purification. Islet quality assessment was performed measuring glucose-stimulated insulin release, viability, islet ATP content, and posttransplant function in diabetic nude mice.RESULTS: Compared with PFD, F6H8S5 significantly increased the intrapancreatic partial oxygen pressure and islet ATP content. This corresponded to an increase of islet yield, recovery after culture, glucose stimulation index, viability, and improved graft function in diabetic nude mice.CONCLUSIONS: The present findings indicate clearly that F6H8S5 improves isolation outcome after prolonged ischemia compared with PFD. This observation seems to be related to the significant lipophilicity and almost pancreas-specific density of F6H8S5. Moreover, these characteristics facilitate pancreas shipment without using custom-made transport vessels as required for PFD.
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| 6. |
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| 7. |
- Brandhorst, Heide, et al.
(författare)
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New class of oxygen carriers improves islet isolation from long-term stored rat pancreata
- 2008
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Ingår i: Transplantation Proceedings. - : Elsevier BV. - 0041-1345 .- 1873-2623. ; 40:2, s. 393-394
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Pancreas shipment is frequently associated with prolonged ischemia deteriorating islet graft function. The strategy to prevent ischemic damage utilizing perfluorodecalin (PFD) for human pancreas oxygenation does not seem to improve isolation outcome. The present study investigated the efficiency of perfluorohexyloctane (F6H8), a hyperoxygen carrier characterized by low specific density (1.33 g/cm3) and lipophilic qualities, to facilitate islet isolation from long-term stored rat pancreata. MATERIALS AND METHODS: Prior to islet isolation, pancreata were intraductally flushed in situ with Kyoto solution (KS) and stored for 24 hours in KS, oxygenated PFD, or F6H8. RESULTS: Islet isolation performed after 24-hour storage in KS failed completely. The intrapancreatic pO2 in PFD- and F6H8-incubated pancreata was almost the same. In correspondence, the ATP content and viability of isolated islets were similar as well. In contrast, islet yield and in vitro function were significantly reduced after storage in PFD compared with F6H8. CONCLUSION: This study suggested that islet isolation performed after long-term pancreas preservation can be significantly improved utilizing semifluorinated alkanes as oxygen carriers.
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| 8. |
- Brandhorst, H., et al.
(författare)
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Quality of Isolated Pig Islets Is Improved Using Perfluorohexyloctane for Pancreas Storage in a Split Lobe Model
- 2013
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Ingår i: Cell Transplantation. - 0963-6897 .- 1555-3892. ; 22:8, s. 1477-1483
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Tidskriftsartikel (refereegranskat)abstract
- Pancreas transportation between donor center and islet production facility is frequently associated with prolonged ischemia impairing islet isolation and transplantation outcomes. It is foreseeable that shipment of pig pancreases from distant centralized biosecure breeding facilities to institutes that have a long-term experience in porcine islet isolation is essentially required in future clinical islet xenotransplantation. Previously, we demonstrated that perfluorohexyloctan (F6H8) is significantly more efficient to protect rat and human pancreata from ischemically induced damage compared to perfluorodecalin (PFD). To evaluate the effect of F6H8 on long-term stored pig pancreases in a prospective study, we utilized the split lobe model to minimize donor variability. Retrieved pancreases were dissected into the connecting and splenic lobe, intraductally flushed with UW solution and immersed alternately in either preoxygenated F6H8 or PFD for 8-10 h. Prior to pancreas digestion, the intrapancreatic pO(2) and the ratio of ATP-to-inorganic phosphate was compared utilizing P-31-NMR spectroscopy. Isolated islets were cultured for 2-3 days at 37 degrees C and subjected to quality assessment. Pancreatic lobes stored in preoxygenated F6H8 had a significantly higher intrapancreatic pO(2) compared to pancreata in oxygen-precharged PFD (10.11 +/- 3.87 vs. 1.64 +/- 1.13 mmHg, p < 0.05). This correlated with a higher ATP-to-inorganic phosphate ratio (0.30 +/- 0.04 vs. 0.14 +/- 0.01). No effect was observed concerning yield and purity of freshly isolated islets. Nevertheless, a significantly improved glucose-stimulated insulin response, increased viability and postculture survival (57.2 +/- 5.7 vs. 39.3 +/- 6.4%, p < 0.01) was measured in islets isolated from F6H8-preserved pancreata. The present data suggest that F6H8 does not increase islet yield but improves quality of pig islets isolated after prolonged cold ischemia.
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| 9. |
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| 10. |
- Brandhorst, Heide, 1962-, et al.
(författare)
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The importance of tryptic-like activity in purified enzyme blends for efficient islet isolation
- 2009
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Ingår i: Transplantation. - 0041-1337 .- 1534-6080. ; 87:3, s. 370-5
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The isolation of islets from the human pancreas critically depends on an efficient enzyme blend. Previous studies have solely focused on the presence of collagenase and neutral protease/thermolysin. Despite improved characterization of these components, the lot-related variability in efficacy still persists suggesting that additional so far disregarded enzymes are required for efficient islet cleavage. METHODS: Varying activities of a tryptic-like enzyme were identified within collagenase NB1 lots, which were selected according to a matched ratio between tryptic-like and collagenase activity (TLA-ratio). Rat and human pancreata were processed with current standard procedures. RESULTS: Increasing the TLA-ratio from 1.3% to 10% reduced pancreas dissociation time in rats by 50% without affecting islet yield, viability, or posttransplant function in diabetic nude mice. Enhancing the TLA-ratio from 1.3% to 12.6% for human pancreas processing resulted in a significant reduction of recirculation time and increased incrementally human islet yield without affecting purity, in vitro function or recovery after culture. Optimized pancreas digestion correlated with a higher percentage of islet preparations fulfilling quality criteria for clinical transplantation. CONCLUSIONS: We conclude that TLA is an effective component that should be included in moderate amounts in enzyme blends for human islet isolation to optimize the efficiency and minimize the lot-related variability.
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