Effects of Acute and Chronic Cyclophosphamide Treatment on Meiotic Progression and the Induction of DNA Double-Strand Breaks in Rat Spermatocytes1
Bibliographic record
Abstract
Male rats treated with cyclophosphamide, an alkylating agent commonly used clinically in both acute and chronic regimens, present with damaged male germ cells and abnormal progeny outcome. The extent and type of damage induced by cyclophosphamide largely depend on the germ cell type exposed to the drug and its ability to respond to insult. In the present study, the response of pachytene spermatocytes to damage was evaluated by assessing their ability to undergo meiotic G2/MI transition following exposure to acute or chronic cyclophosphamide. Male rats were given an acute high dose (70 mg/kg, once) or chronic low doses (6 mg/kg, daily for 5-6 wk) of cyclophosphamide. Pachytene spermatocytes were isolated, cultured, and induced to undergo G2/MI transition with okadaic acid. To determine the effect of DNA damage on meiotic progression, induction of DNA double-strand breaks was detected after each treatment regimen by the formation of foci of phosphorylated histone H2AX. The transition from G2 to MI was impaired after acute cyclophosphamide treatment; this impairment in the progression of pachytene spermatocytes was correlated with extensive DNA double-strand breaks. In contrast, despite the presence of significant levels of DNA damage, meiotic progression was not impaired in spermatocytes after chronic cyclophosphamide exposure. We suggest that the cell cycle impairment induced after acute cyclophosphamide treatment could be mediated by a G2/M checkpoint activated in response to DNA damage. The absence of impairment after chronic treatment raises concern about the functionality of defense mechanisms in male germ cells after repeated exposure to low doses of genotoxic agents.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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 | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".