Hydroxyapatite-coated cardiovascular stents.
Bibliographic record
Abstract
Description and history Extensive clinical practice supported with evidence gathered during numerous animal studies has shown that in addition to its excellent biocompatibility, hydroxyapatite (HAp, a crystalline derivative of calcium phosphate) is non-toxic and does not induce allergic or inflammatory reactions. The latest research on HAp appears to confirm that HAp crystals “do not acquire a pro-inflammatory or thrombogenic phenotype, but express markers of functioning endothelium that might contribute to angiogenesis.”1 The new generation of non-polymeric drug-eluting cardiovascular stents (as compared to polymer-coated stents) is expected to offer drug delivery solutions which will be less thrombogenic and more tolerable by the body environment (less restenotic) while, at the same time, capable of delivering the desired quantity of drugs in a manner that reflects recommendations of scientists, and responding to the reallife needs and abilities of the patient. These generic observations prompted MIV Therapeutics Inc. to consider HAp as a coating suitable for drug delivery on cardiovascular stents. Such HAp coated stents are being developed within the collaborative research and development program between University of British Columbia, and MIV Therapeutics Inc., both located in Vancouver, BC, Canada. The challenge is that the brittleness of ceramic HAp coating has to withstand deformation during stent crimping and implantation, and remain undamaged and biologically inert years after the implantation into arteries of human heart. In response to this challenge, several novel coating technologies have been developed in 20032005 for deposition of HAp ceramics on stents and other implantable medical devices, by combined efforts and ingenuity of the teams of MIV Therapeutics, Inc. and University of British Columbia. Technical specifications “Wet” chemical technologies were used for deposition of ultra-thin (0.1-0.2 μm) and micro-thin (0.3-1.0 μm) HAp coatings. The ultrathin films composed of high-density non-porous hydroxyapatite are designated primarily as a biocompatible surface modification of metallic implants, whereas the micro-thin films which possess highly porous structure were developed and evaluated also as a potential vehicle for effective and highly engineerable drug delivery. The deposition of the 0.1-0.2 μm ultra-thin films of HAp ceramics used sol-gel (SG) subjected to heat treatment at 450°C which ensured their structural integrity and necessary mechanical properties. The resulting SG-HAp Class “0” ultra-thin “passive” (drug-free) coatings are very well bonded to metal substrates such as stainless steel or Co-Cr alloys, feature acceptably smooth surface (Figure 1) and survive undamaged the stent crimping-implanting-expansion proce-
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.011 | 0.012 |
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".