| 1. |
- 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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| 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. |
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| 4. |
- Caballero-Corbalán, José, et al.
(författare)
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Using HTK for Prolonged Pancreas Preservation Prior to Human Islet Isolation
- 2012
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Ingår i: Journal of Surgical Research. - : Elsevier BV. - 1095-8673 .- 0022-4804. ; 175:1, s. 163-168
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Tidskriftsartikel (refereegranskat)abstract
- Background. Histidine-tryptophan-ketoglutarate (HTK) has been established as an alternative to University-of-Wisconsin solution (UWS) for abdominal organ preservation, but data about HTK efficiency to preserve pancreata during prolonged cold ischemia time (CIT) are conflicting. In human islet transplantation, HTK provided similar isolation outcomes after short CIT. The present study aimed to investigate whether islets can be successfully isolated from HTK-preserved pancreata after prolonged CIT compared with UWS. Materials and Methods. Sixty-four human pancreata retrieved from donors meeting criteria for kidney donation were perfused utilizing either HTK or UWS and preserved for more or less than 10 h prior to islet isolation. Along with parameters related to isolation and islet quality assessment, the dry-to-wet weight ratio was evaluated. Results. Donor-and procurement-related factors did not vary between HTK- and UWS-perfused pancreata. The dry-to-wet weight ratio was lower in HTK-preserved pancreata indicated tissue edema (21.0% +/- 3.5% versus 24.8% +/- 2.0%, P = 0.007). Isolation-related variables differed between experimental groups after prolonged CIT with respect to purified packed tissue volume (9.1 +/- 5.0 versus 17.2 +/- 8.1 mu L/g, P = 0.004) and islet yield (1910 +/- 980 versus 3150 +/- 1420 IE/g, P = 0.012). Islet purity and survival after culture were similar after HTK or UWS perfusion. The preservation solution did not affect in vitro function and transplantability of isolated islets. Conclusions. Compared with UWS, HTK has similar efficiency to preserve human pancreata for subsequent islet isolation during <10 h CIT but seems to be limited for prolonged cold storage. (C) 2012 Elsevier Inc. All rights reserved.
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| 5. |
- Friberg, Andrew S., et al.
(författare)
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Transplanted functional islet mass : donor islet preparation, and recipitent factors influence early graft function in islet-after-kidney patients
- 2012
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Ingår i: Transplantation. - 0041-1337 .- 1534-6080. ; 93:6, s. 632-638
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Tidskriftsartikel (refereegranskat)abstract
- Background.The ability to predict clinical function of a specific islet batch released for clinical transplantation using standardized variables remains an elusive goal.Methods. Analysis of 10 donor, 7 islet isolation, 3 quality control, and 6 recipient variables was undertaken in 110 islet-after-kidney transplants and correlated to the pre- to 28-day posttransplant change in C-peptide to glucose and creatinine ratio ([DELTA]CP/GCr).Results.Univariate analysis yielded islet volume transplanted (Spearman r=0.360, P<0.001) and increment of insulin secretion (r=0.377, P<0.001) as variables positively associated to [DELTA]CP/GCr. A negative association to [DELTA]CP/GCr was cold ischemia time (r=-0.330, P<0.001). A linear, backward-selection multiple regression was used to obtain a model for the transplanted functional islet mass (TFIM). The TFIM model, composed of islet volume transplanted, increment of insulin secretion, cold ischemia time, and exocrine tissue volume transplanted, accounted for 43% of the variance of the clinical outcome in the islet-after-kidney data set.Conclusion.The TFIM provides a straightforward and potent tool to guide the decision to use a specific islet preparation for clinical transplantation.
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| 6. |
- Höst, Gunnar E., 1976-, et al.
(författare)
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Methods for investigating students’ learning and interaction with a haptic virtual biomolecular model
- 2010
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Ingår i: Contemporary Science Education Research: International Perspectives. - Ankara : Pegem Akademi. - 9786053640318 ; , s. 115-121
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Konferensbidrag (refereegranskat)abstract
- Although immersive haptic virtual technologies are emerging rapidly in modern education, few methods exist for delivering data on the pedagogical merits of such models in the molecular life sciences. This paper reports on a selection of methods that we have used to obtain and analyse data on students’ learning and interaction with a haptic virtual model of protein-ligand docking, previously designed by author PBP. The methods have been developed and employed during four consecutive years in which the model has been part of an advanced biomolecular interactions course. In this regard, we present data-collection methods that include written items, interviews, think-aloud tasks and automated time-stamped logs and, corresponding quantitative and qualitative analytical procedures such as pre/posttest statistical comparisons, word usage analysis and, visualised profiling of students’ interaction with the model. Our results suggest that these methods are useful for generating valuable information on students’ learning gain, changes in conceptual understanding, reasoning processes and patterns of interactivity with the model. Dissemination of such methods could provide an empirical contribution to the dearth of research instruments in this domain. Future research will develop these methodologies to explore the relationship between using the model and students’ conceptual and embodied learning.
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| 7. |
- Höst, Gunnar E., 1976-, et al.
(författare)
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Student Learning about Biomolecular Self-Assembly Using Two Different External Representations
- 2013
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Ingår i: CBE - Life Sciences Education. - Bethesda, USA : American Society for Cell Biology. - 1931-7913. ; 12:3, s. 471-482
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Tidskriftsartikel (refereegranskat)abstract
- Self-assembly is the fundamental but counterintuitive principle that explains how ordered biomolecular complexes form spontaneously in the cell. This study investigated the impact of using two external representations of virus self-assembly, an interactive tangible three-dimensional model and a static two-dimensional image, on student learning about the process of self-assembly in a group exercise. A conceptual analysis of self-assembly into a set of facets was performed to support study design and analysis. Written responses were collected in a pretest/posttest experimental design with 32 Swedish university students. A quantitative analysis of close-ended items indicated that the students improved their scores between pretest and posttest, with no significant difference between the conditions (tangible model/image). A qualitative analysis of an open-ended item indicated students were unfamiliar with self-assembly prior to the study. Students in the tangible model condition used the facets of self-assembly in their open-ended posttest responses more frequently than students in the image condition. In particular, it appears that the dynamic properties of the tangible model may support student understanding of self-assembly in terms of the random and reversible nature of molecular interactions. A tentative difference was observed in response complexity, with more multifaceted responses in the tangible model condition.
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