[Effect of changes in posterior tibial slope on the mid-term clinical outcomes of Oxford unicompartmental knee arthroplasty]

Objective: To investigate the impact of changes in the posterior tibial slope (PTS) in Oxford unicompartmental knee arthroplasty (OUKA) on the mid-term clinical outcomes of postoperative patients. Methods: This study was a follow-up study. The data of 135 patients (150 knees) who underwent OUKA at the China-Japan Friendship Hospital from January 2012 to January 2013 were analyzed retrospectively. The patients were followed-up for at least ten years. According to the changes in PTS of the medial tibial plateau before and after surgery, patients were divided into three groups: group A (PTS decreased by more than 5°), group B (PTS changed by 5° or less), and group C (PTS increased by more than 5°). The Knee Society Clinical Score (KSS-C), Knee Society Functional Score (KSS-F), Oxford Knee Score (OKS), Forgotten Joint Score (FJS), and knee range of motion (ROM) among the three groups were compared at the last follow-up. Results: Prior to the final follow-up assessment, six patients expired, and an additional nine patients were lost to follow-up. A total of 120 patients (135 knees) were enrolled in this study (30 males and 90 females). The mean age was (66.29±8.62) years, and the follow-up time was (10.54±0.72) years. Group A consisted of 32 patients (34 knees), group B comprised 77 patients (90 knees), and group C included 11 patients (11 knees). One knee in group A suffered prosthesis loosening, and two knees in group C experienced postoperative bearing dislocation, one knee encountered bearing fragmentation. The incidence of postoperative complications differed significantly among the three groups (P<0.05). The preoperative OKS was (33.91±6.59) points, KSS-F was (43.46±8.99) points, KSS-C was (41.05±5.70) points and ROM was 115.23°±13.53°; after the surgery, they changed to (18.82±7.01) points, (81.51±7.34) points, (82.64±7.94) points, and 119.07°±8.62°, respectively, and all the differences were statistically significant (all P<0.001). In terms of postoperative outcomes, group A had an OKS of (21.44±8.46) points and a FJS of (63.83±11.40) points, group B had an OKS of (17.07±5.81) points and a FJS of (70.49±12.45) points, group C had an OKS of (25.09±5.07) points and a FJS score of (59.48±10.09) points; the differences among the three groups were all statistically significant (all P<0.05), but there were no significant differences in the postoperative KSS scores and ROM among the three groups (all P>0.05). Conclusions: After OUKA, better mid-term clinical outcomes are achieved when ΔPTS is<5°. Although the recommended central value for PTS in OUKA is 7° according to Oxford, it should be individualized, and it is recommended to consider the preoperative angle, with a change of less than 5° before and after surgery.

Two independent DNA repair pathways cause mutagenesis in template switching deficient Saccharomyces cerevisiae

Upon DNA replication stress, cells utilize the postreplication repair pathway to repair single-stranded DNA and maintain genome integrity. Postreplication repair is divided into 2 branches: error-prone translesion synthesis, signaled by proliferating cell nuclear antigen (PCNA) monoubiquitination, and error-free template switching, signaled by PCNA polyubiquitination. In Saccharomyces cerevisiae, Rad5 is involved in both branches of repair during DNA replication stress. When the PCNA polyubiquitination function of Rad5 s disrupted, Rad5 recruits translesion synthesis polymerases to stalled replication forks, resulting in mutagenic repair. Details of how mutagenic repair is carried out, as well as the relationship between Rad5-mediated mutagenic repair and the canonical PCNA-mediated mutagenic repair, remain to be understood. We find that Rad5-mediated mutagenic repair requires the translesion synthesis polymerase ζ but does not require other yeast translesion polymerase activities. Furthermore, we show that Rad5-mediated mutagenic repair is independent of PCNA binding by Rev1 and so is separable from canonical mutagenic repair. In the absence of error-free template switching, both modes of mutagenic repair contribute additively to replication stress response in a replication timing-independent manner. Cellular contexts where error-free template switching is compromised are not simply laboratory phenomena, as we find that a natural variant in RAD5 is defective in PCNA polyubiquitination and therefore defective in error-free repair, resulting in Rad5- and PCNA-mediated mutagenic repair. Our results highlight the importance of Rad5 in regulating spontaneous mutagenesis and genetic diversity in S. cerevisiae through different modes of postreplication repair.

Smooth muscle tumors of the gastrointestinal tract. Expression of ras P21 oncogene product and the association with clinicopathology

Quantitative analysis of ras oncogene product P21 was performed on paraffin blocks from 55 smooth muscle tumors of the gastrointestinal tract by immunofluorescence and flow cytometry. No positive evidence for P21 was found in 5 cases of normal smooth muscle tissues. Eight of 14 leiomyomas were P21 positive (57%) but all of them were lower expressed with fluorescence index (FI) < 1.25, whereas a total of 29 leiomyosarcomas and 12 potential malignant smooth muscle tumors were found to be P21 positive (100%), and the majority were overexpressed with FI > 1.25 (P < 0.005). ras P21 was overexpressed significantly in the tumors with mitotic counts of more than 1/10 high power field (P < 0.005). It was also overexpressed significantly as soon as the mild cytologic atypia of the tumor was found (P < 0.005). Five-year survival rate was significantly higher in the patients with lower-expression of ras P21 than those with overexpression (P < 0.005). It was suggested that the expression of ras oncogene product P21 could be used as an objective parameter in distinguishing malignants from benigns and predicting the prognosis of the patients with smooth muscle tumors of the gastrointestinal tract.

[Flow cytometric quantitation of p53 protein expression in gastrointestinal smooth muscle tumors: clinicopathological correlation and prognostic significance]

Quantitative analysis of p53 protein expression was performed on paraffin-embedded tissues from 55 smooth muscle tumors of the gastrointestinal tract by using immunofluorescence and flow cytometry. No positive expression was found in normal smooth muscle tissues of the gastrointestinal tract. Overexpression of p53 gene was found in a significantly higher proportion in leiomyosarcomas (90%) and potential malignant smooth muscle tumors (75%) compared to leiomyomas (14%) (P < 0.005). The quantitation of p53 expression was found to be progressively enhanced in the sequence from leiomyoma through potential malignant smooth muscle tumor to leiomyosarcoma (P < 0.005). It was also overexpressed when mitotic counts were more than 1/10HPF or the mild cytologic atypia was found (P < 0.005). Five year survival rate was significantly higher in the patients with p53 lower expression compared to the patients with over-expression (P < 0.005). These results suggested that p53 overexpression might be associated with the transformation of leiomyoma into leiomyosarcoma, and could be used as an objective parameter in distinguishing malignants from benigns and predicting prognosis of the patients with smooth muscle tumors of the gastrointestinal tract.