IMAGING OF EARLY POST-ISLET TRANSPLANT EVENTS BY POSITRON EMISSION TOMOGRAPHY (PET)
Bibliographic record
Abstract
P685 Aims: Since the implementation of the Edmonton protocol, islet transplantation results have improved significantly. However, recipients achieve beta-cell functions of only 20% of that of healthy subjects, although most have received islets from more than one donor. This suboptimal function is the result of a loss of endocrine cells, which is thought to occur mainly as an early post-transplant event, as often reflected by a peak of C-peptide in the first hours after implantation. Imaging of the islets could be a powerful tool to assess their fate early after implantation. Methods: Sprague-Dawley (SD) rat islets (300IEq) were incubated with fluoro-deoxy-glucose (FDG) in DMEM during various incubation times and with various concentrations of FDG or glucose. After washing, radioactivity included in the islets was measured in an activimeter. After incubation, islet viability was assessed by propidium iodide/fluorescein diacetate staining. In vivo: intraportal injections of FDG alone or of radiolabeled islets (2000IEq) with or without pre-treatment with heparin were performed in SD rats (3 per group). Positron emission tomographies were performed hourly during the first 6 hours after transplantation. Radioactivity uptake was measured in liver, lung, brain, kidneys, heart and bladder and was expressed as % of uptake (radioactivity in a specific organ/total injected radioactivity). Results: In vitro: FDG uptake increased with incubation time or concentration of FDG before reaching a plateau at 60min incubation or 3MBq FDG. Uptake decreased with increasing concentrations of glucose, reflecting a competition for the same channel. Islet viability was unmodified by FDG. In vivo: after injection, all islets remained in the liver, with an uptake 4.35-fold higher compared to control injected with FDG alone (44.2% vs 10.1%). In the other organs, the uptake was similar to control. Heparin did not improve primary islet integration in the liver and did not modify the decrease of radioactivity during the 6 first hours after transplantation compared to untreated islet isotransplantations. Conclusions: Ex-vivo radio-labeling of islets and study of post-islet transplant events by positron emission tomograghy imaging is feasible. This method allows follow-up of the islets and testing of various strategies or treatments in order to improve islet implantation and survival.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".