Increases in concentric hypertrophy are driven by natural selection in the Spontaneously Hypertensive Rat Colony
Bibliographic record
Abstract
Background Heart failure (HF) is a global health concern that affects nearly 26 million people each year. The Spontaneously Hypertensive Rat (SHR) was established in 1963 and is the most commonly used rodent model for studying human HF. Unlike humans, the SHRs develop hypertension around their reproductive age (i.e., when animals are selected for breeding), providing the opportunity for natural selection towards adaptive traits for hypertension‐induced heart failure. Therefore, the primary objective of this review was to evaluate whether SHRs have evolved over time to the cardiac sequelae of hypertension. We hypothesized that, while the severity of hypertension will remain stable within the SHR colony, the HF phenotype will become less pronounced with time as a result of compensatory changes to manage high blood pressure. Methods We performed a retrospective review evaluating several indices of cardiovascular health in the SHR over the past 60 years. For statistical analyses, studies that met the inclusion criteria were separated into 2 cohorts: Initial (mid‐late 1900’s) and Current (early 2000’s ‐present) Colony SHRs. Wistar‐Kyoto rats (i.e., normotensive rats used to establish the SHR line via selective breeding) were used as controls to normalize changes in technique and methods that have occurred over these decades. Results Systolic blood pressure did not differ between Initial and Current Colony SHRs, indicating that the severity of hypertension had remained stable within the SHR Colony over time. Current Colony SHRs presented with increased cardiac concentric hypertrophy (i.e., elevated heart weight and posterior wall thickness). Since these changes were not observed in the Wistar‐Kyoto control rats, cardiac‐derived changes in Current Colony SHRs were unlikely due to differences in techniques, equipment, anesthesia or environmental conditions. Conclusion These findings establish that the SHR colony has evolved over time, with greater concentric hypertrophy. Using natural selection to find positive adaptive traits may be advantageous in identifying new therapeutic treatment strategies.
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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 | 0.003 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".