In vivo assessment of second generation implantable laser Doppler flowmetry fibres for bone blood flow determination.
Bibliographic record
Abstract
BACKGROUND: Standard laser Doppler flowmetry (LDF) requires application of a probe directly onto tissue for blood flow measurement. Repeated surgical exposures are necessary for assessments over time, making nonanaesthetized measurements unfeasible. Implantable fibres offer a method of assessing tissue perfusion without surgical reexposure and additional time expenditure. Prior in vivo studies showed that first generation implantable LDF fibres experienced early fatigue failure due to their percutaneous exit site, predisposing them to trauma. A second generation of implantable fibres has been developed with silastic coatings to improve durability. AIMS: This investigation determined the reliability of second generation LDF fibres' blood flow measurements compared to standard LDF probe readings, using a segmental tibial fracture model in 11 large adult dogs. METHODS: The fractures were stabilized by compression plates. LDF was used to determine cortical bone perfusion: (1) prefracture (2) postfracture (3) immediately postplating (4) at 5 weeks and (5) at 10 weeks, at four sites along the tibia. Two probe designs were used: (1) standard metal-sheathed probe (2) modified probe with a coupling unit for attachment to 1-mm, flexible silastic-coated fibres. The proximal end of the fibre was implanted in cortical bone, and the distal end subcutaneously for protection. At 5 weeks postplating, minimal surgical dissection was needed to locate the distal fibre tips for measurements. Following euthanasia after 10 weeks, lower extremity lymph nodes and soft tissues surrounding the fibres were removed for histology. RESULTS: At 5 weeks, 42 of 44 fibres (95%) implanted were intact. At 10 weeks, 75% were intact. The fibres did not incite a foreign body response at 10 weeks. At 5 weeks postplating, implantable fibre LDF values increased over acute postplating levels (p = 0.009), indicating that the fibres could detect cortical bone revascularization. Significant correlations between the standard probe and implantable fibre bone blood flow values occurred in 22% of measurements. This approaches the 33% correlation between standard probe and cerium microsphere entrapment for blood flow measurement. CONCLUSION: The second generation fibres were more durable over time than first generation fibres. While implantable fibres can assess bone blood flow without repeated tissue exposure, further modifications are needed for use in clinical settings.
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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 | 0.001 | 0.001 |
| 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 | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".