Plasma homocysteine concentration is not associated with activated protein C resistance in patients investigated for hypercoagulability
Bibliographic record
Abstract
Homocysteine and activated protein C (aPC) resistance are known risk factors for thromboembolism, but how elevated homocysteine influences thrombogenicity is not fully understood. The possibility that homocysteine may exert a pro-thrombotic effect by inducing aPC resistance has been addressed, with conflicting conclusions. The aim of this study is to evaluate the possible relationship of serum homocysteine concentration to aPC resistance in a cohort of patients investigated for hypercoagulability. Laboratory records from 1011 consecutive patients referred to the Haemostasis Laboratory at the Health Sciences Centre (Winnipeg, Canada) were reviewed from February 1997 to November 2002. Homocysteine levels, normalized aPC sensitivity ratio (aPC-SR), and Factor V Leiden genotype were recorded for all 1011 patients. 394 patients had aPC-SR determined by mixing the patient plasma in 4 parts FV deficient plasma (FV-deficient-mix assay), and 617 patients had aPC-SR calculated without mixing (neat assay). Homocysteine did not significantly influence the aPC-SR when using the FV deficient assay. When aPC-SR was measured using the neat assay, homocysteine was found to correlate inversely with the degree of aPC resistance. The mean aPC-SR of FV Leiden-negative subjects measured using the neat assay was substantially lower than the expected normalized value of 1.0 that was obtained when aPC-SR was measured with the FV-deficient-mix assay. aPC resistance is common in patients being evaluated for possible hypercoagulability. In these patients, elevated plasma homocysteine levels is not associated with aPC resistance regardless of FV Leiden genotype suggesting that this is not the mechanism by which homocysteine exerts a prothrombotic effect.
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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 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".