Melamine-Containing Crystals in the Urinary Tracts of Domestic Animals: Sentinel Event?
Bibliographic record
Abstract
To the Editor.—Recent reports of contamination of food products intended for human consumption with melamine have raised numerous questions internationally regarding the possible adverse health effects of melamine consumption in humans.In the spring of 2007, melamine contamination of vegetable proteins imported from China and used in pet food manufacture led to the announcement of a massive pet food recall by the US Food and Drug Administration (FDA).1 Domestic cats and dogs developed acute renal failure and many animal deaths were reported. Although we have not seen detailed reports yet in Western medical journals of the pathology associated with melamine consumption in humans, urinary stone formation has been reported in the media.2The pathogenesis of renal toxicity associated with melamine ingestion may not have been fully elucidated yet, but intratubular crystals containing melamine were observable in routine formalin-fixed, paraffin-embedded kidney sections from domestic animals. The University of Guelph, Canada, published features of these crystals detected in cat urine, including their infrared spectral characteristics online in 2007 (http://www.labservices.uoguelph.ca/urgent.cfm, accessed October 29, 2008).We have examined formalin-fixed, paraffin-embedded renal tissue from dogs and cats that died as a result of acute renal failure after the consumption of food included in the 2007 FDA pet food recall. We believe that it may be of value for pathologists to be familiar with the histologic and chemical analytic features of the melamine-containing crystals.In routine hematoxylin-eosin– stained sections, the melamine-containing crystals are brown or green, are located within renal tubules, and have a rough surface appearance (Figure, A). The crystals are rounded, often have a radial lamellar orientation, and are brightly birefringent when viewed under polarized light. The crystals do not stain with histochemical stains commonly used for the detection of calcium (von Kossa and Alizarin red), but will stain with oil red O, a stain for lipids, which has been noted to stain many plastics (Figure, B).Infrared spectroscopy (IR) is commonly used for the chemical analysis of renal calculi, and the IR characteristics of melamine-containing crystals prepared in vitro and seen in vivo are distinct and reproducible. This technique can also be used in formalin-fixed, paraffin-embedded tissue.Calcium oxalate crystals are frequently seen in the same kidney sections that display melamine-containing crystals; however, they can be distinguished by histochemical stains or IR, if required.Physicians involved with urine analysis or renal pathology, who may be unfamiliar with the veterinary literature, may benefit from recognizing the features of the pet food–associated melamine crystals should similar crystals be present in human cases. If this should arise veterinary pathology will have played a further sentinel role in medicine. More detailed descriptions of the pet food– associated melamine-containing urinary tract crystals have been recently published.3–5
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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 | 0.002 | 0.012 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.010 | 0.006 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
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".