Characterization of phosphorus content of biological samples by ICP-DRC-MS: potential tool for cancer research
Bibliographic record
Abstract
Phosphorus and sulfur are detected as phosphorus oxide and sulfur oxide ions (PO+ and SO+), produced by oxidation reactions with O2 performed in the reaction cell of the inductively coupled plasma dynamic reaction cell mass spectrometer (ICP-DRC-MS), at sub-ng mL−1 detection limits. This allows pM mL−1 detection of phospho-proteins, with S used as an internal standard (see ref. 9). The method was applied to digests (in HCl) of in-vitro tyrosine kinase assays, both as an evaluation of kinase autophosphorylation and phosphorylation of substrate. Detecting the phosphorus/sulfur ratio (via measured PO+/SO+) in cell cultures is shown to provide a distinguishable difference between malignant cell lines and primary cultures. The PO+/SO+ ratio for human colorectal adenocarcinoma (CRC) tissue samples compared with matched normal (N) tissue samples from the same patients is shown to be higher, at (PO+/SO+)CRC/(PO+/SO+)N = 1.75 ± 0.18 (n = 4). Samples used in this analysis were of needle biopsy amounts (0.2–0.5 mg), with a greater than 70% tumor burden in CRC. The phospho-protein phosvitin is detected directly from dried one-dimensional polyacrylamide gels using laser ablation ICP-MS by detecting phosphorus at sub-nM amounts. The phosphorus detection limit for direct ablation, assessed from ablating gel doped with P and blank gel, is 0.6 µg g−1 in gel. Direct detection of sulfur from the gels is obscured by the high sulfur background for the blank gels, which is attributed to the sulfur-containing catalysts used in polymerization and to sodium dodecyl sulfate (SDS) used for protein denaturing.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".