Reliability of the rabbit postero-lateral spinal fusion model: A meta-analysis.

The rabbit model of spinal fusion with the autogenous iliac crest bone graft (ICBG) control is widely used to evaluate bone graft substitutes and enhancers. This study examined the reliability of this model using meta-analysis. A systematic literature search from January 1995 to May 2011 identified 56 studies, involving 733 animals. The primary outcome was fusion success calculated as logit event rate. Study design, surgical technique, rabbit characteristics (gender, species, age, weight), and institution were analyzed. Overall fusion success was 52.4%. Important positive variables were time-point >4 weeks, ICBG dose >1 cm(3) , initial weight of animals ≥3 kg, level at L4-5 or L5-6, and age ≥6 months. Inter- and intra-institutional reliability was excellent. The rabbit model ICBG control group is reliable, although several factors can affect results. Fusion under normal handling occurs reliably in 5 weeks. The volume of bone graft should be >1 cm(3) but no benefits are present with >2 cm(3) . The animals should weigh a minimum of 3 kg and be at least 6 months old.

Utility of micro-ribonucleic acid profile for predicting recurrence of rectal cancer.

BACKGROUND: In early-stage rectal cancer, the surgeon must decide between the high morbidity of radical surgery and the high recurrence rates of local excision. A prognostic marker could improve patient selection and lower recurrence rates. Micro-ribonucleic acids (miRNAs), small RNAs that often inhibit tumor suppressors, have shown prognostic potential in colorectal cancer. We hypothesized that high miRNA levels in malignant tissue from early-stage rectal cancer patients could predict recurrence after local excision. MATERIALS AND METHODS: We identified 17 early-stage rectal cancer patients treated with local excision between 1990 and 2005, four of whom had recurrences. Total RNA was extracted from benign and malignant tissue and used in quantitative real-time reverse transcriptase polymerase chain reaction to probe for miR-20a, miR-21, miR-106a, miR-181b, and miR-203. MiRNA data were evaluated for association with recurrence using univariate analysis with Wilcoxon rank sum test. RESULTS: Malignant tissue in both patients who had recurrences and patients who did not have recurrences had equivalently high levels of miRNA. However, the benign tissue of patients who recurred contained significantly higher levels of all five miRNAs when compared with the benign tissue of nonrecurrent patients despite having no histological differences. CONCLUSIONS: This is the first study to show that high miRNA levels of histologically benign tissue obtained from the surgical margin of locally excised rectal cancers can predict recurrence. The malignant miRNA levels did not have predictive value. Further investigation of miRNAs is needed to explore their potential for a more accurate prognosis of rectal cancer.