Indian Hedgehog (IHH) signaling, a key regulator of skeletal development, is highly activated in cartilage and bone tumors. Yet deletion of Ptch1, encoding an inhibitor of IHH receptor Smoothened (SMO), in chondrocyte or osteoblasts does not cause tumorigenesis. Here, we show that Ptch1 deletion in mice Prrx1+mesenchymal stem/stromal cells (MSCs) promotes MSC proliferation and osteogenic and chondrogenic differentiation but inhibits adipogenic differentiation. Moreover, Ptch1 deletion led to development of osteoarthritis-like phenotypes, exostoses, enchondroma, and osteosarcoma in Smo-Gli1/2-dependent manners. The cartilage and bone tumors are originated from Prrx1+ lineage cells and express low levels of osteoblast and chondrocyte markers, respectively. Mechanistically, Ptch1 deletion increases the expression of Wnt5a/6 and leads to enhanced β-Catenin activation. Inhibiting Wnt/β-Catenin pathway suppresses development of skeletal anomalies including enchondroma and osteosarcoma. These findings suggest that cartilage/bone tumors arise from their early progenitor cells and identify the Wnt/β-Catenin pathway as a pharmacological target for cartilage/bone neoplasms.
Background/Aims: Acute kidney injury (AKI) is common following cardiac surgery and predicts a poor outcome. However, the early detection of AKI has proved elusive and most cases are diagnosed only following a significant rise in serum creatinine (SCr). We compared a panel of early biomarkers of AKI for the detection of AKI in patients undergoing heart surgery. This study included serum cystatin C (CyC) and urinary levels of neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), retinol-binding protein (RBP) and N-acetyl-β-D-glucosaminidase (NAG). Methods: We retrospectively identified 15 patients undergoing open cardiac surgery who developed AKI within 72 h postoperatively. For these, we identified 15 matched controls also having undergone surgery but without AKI. Serial serum and urine samples had prospectively been postoperatively obtained from all patients at 0, 2, 4, 6, 10, 24, 48 and 72 h after admission to the intensive care unit. AKI was defined as a >50% increase in SCr. CyC was measured by nephelometry, while NGAL, IL-18, and RBP were measured by ELISA and NAG was measured by spectrophotometry. The urinary biomarkers were normalized to urinary creatinine (UCr) concentration. Each marker was assessed at each time point for its predictive value using receiver operating characteristic curves to predict AKI. Results: Following the exclusion of 1 case due to a urinary tract infection, the final cohort consisted of 29 patients aged 62.9 ± 13.7 years with baseline SCr of 73.2 ± 11.9 µmol/l. While there were no differences in the demographics between cases and controls, the aortic clamp time was predictably higher in AKI cases than in controls (60.6 ± 13.9 vs. 43.0 ± 9.2 min, p < 0.05). Each biomarker differed significantly between cases and controls for at least one time point. The optimal area under the curve (AUC) was for CyC at 10 h (sensitivity 0.71, specificity 0.92, cutoff 1.31 mg/l), NGAL at 0 h (sensitivity 0.84, specificity 0.80, cutoff 49.15 µg/g UCr), IL-18 at 2 h (sensitivity 0.85, specificity 0.73, cutoff 285.65 ng/g UCr), RBP at 0 h (sensitivity 0.75, specificity 0.67, cutoff 2,934.65 µg/g UCr) and NAG at 4 h (sensitivity 0.86, specificity 0.67, cutoff 37.05 U/mg UCr). Using a combination of all 5 biomarkers analyzed at the optimal time point as above, we were able to obtain an AUC of 0.98 (0.93–1.02, p < 0.001) in this limited sample. Conclusion: The use of serum and urinary biomarkers for the prediction of AKI in patients undergoing cardiac surgery is highly dependent on the sampling time. Of the evaluated markers urinary NGAL had the best predictive profile. The previously unstudied marker of urinary RBP showed similar predictive power as more established markers. By combining all 5 studied biomarkers we were able to predict significantly more cases, suggesting that the use of more than one marker may be beneficial clinically.
<b><i>Background/Aims:</i></b> Cardiac surgery-associated severe acute kidney injury (SAKI) is associated with high mortality and poor quality of life. A prognostic score for SAKI may enable prevention of complications. Methods: This observational study of 2,552 patients undergoing cardiac surgery from January 2006 to December 2011 in our institution established associations between predictor variables and postoperative SAKI from a cohort of 1,692 patients and developed a clinical score that was assessed in a validation cohort of 860 patients. <b><i>Results:</i></b> Postoperative SAKI occurred in 262 patients (10.3%). We identified 7 independent and significant risk factors in the derivation model (adjusted OR 95% CI): age ≥81 years (vs. age < 40 years, 4.30, 1.52–12.21), age 61–80 years (vs. age < 40 years, 2.84, 1.24–6.52), age 41–60 years (vs. age < 40 years, 1.62, 0.68–3.87), hypertension (1.65, 1.13–2.39), previous cardiac surgery (3.62, 1.27–10.32), hyperuricemia (2.02, 1.40–2.92), prolonged operation time (1.32, 1.17–1.48), postoperative central venous pressure < 6 mm H<sub>2</sub>O (3.53, 2.38–5.23), and low postoperative cardiac output (4.78, 2.97–7.69). The 7-variable risk prediction model had acceptable performance characteristics in the validation cohort (C statistic 0.80, 95% CI 0.74–0.85). The difference in the C statistic was 0.21 (95% CI 0.12–0.29, <i>p</i> < 0.001) compared with the Cleveland Clinic score. <b><i>Conclusion:</i></b> We developed and validated a practical risk prediction model for SAKI after cardiac surgery based on routinely available perioperative clinical and laboratory data. The prediction model can be easily applied at the bedside and provides a simple and interpretable estimation of risk.
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