Meta-analysis with zero-event studies: a comparative study with application to COVID-19 data.

BACKGROUND: Meta-analysis is a statistical method to synthesize evidence from a number of independent studies, including those from clinical studies with binary outcomes. In practice, when there are zero events in one or both groups, it may cause statistical problems in the subsequent analysis. METHODS: In this paper, by considering the relative risk as the effect size, we conduct a comparative study that consists of four continuity correction methods and another state-of-the-art method without the continuity correction, namely the generalized linear mixed models (GLMMs). To further advance the literature, we also introduce a new method of the continuity correction for estimating the relative risk. RESULTS: From the simulation studies, the new method performs well in terms of mean squared error when there are few studies. In contrast, the generalized linear mixed model performs the best when the number of studies is large. In addition, by reanalyzing recent coronavirus disease 2019 (COVID-19) data, it is evident that the double-zero-event studies impact the estimate of the mean effect size. CONCLUSIONS: We recommend the new method to handle the zero-event studies when there are few studies in a meta-analysis, or instead use the GLMM when the number of studies is large. The double-zero-event studies may be informative, and so we suggest not excluding them.

[Clinical effects of suture anchor with V-Y tenoplasty in treating old Achilles tendon rupture].

OBJECTIVE: To explore clinical effects of suture anchor with V-Y tenoplasty for the treatment of old Achilles tendon rupture. METHODS: From May 2014 to March 2018, 26 patients with old Achilles tendon rupture treated by suture anchor with V-Y tenoplasty, including 18 males and 8 females aged from 19 to 56 years old with an average of (36.0±11.7) years old, the courses of disease ranged from 42 to 62 days with an average of (49.0±5.3) days; the distances of Achilles tendon-shortening ranged from 2 to 7 cm with an average of (4.0±1.6) cm. Postoperative complications were observed, preoperative and postoperative American Orthopaedic Foot and Ankle Soviety(AOFAS) score were used to evaluate clinical effects. RESULTS: All patients were followed up from 8 to 18 months with an average of(12.0±2.5) months. No Achilles tendon rupture occurred again. Postoperative AOFAS score at 3 months(93.37 ±3.48) was higher than before operation(57.26±5.06)(t=9.564, P<0.05), and 14 patients got excellent results, 11 moderate and 1 poor. CONCLUSIONS: Suture anchor with V-Y tenoplasty for old Achilles tendon rupture could achieve stable fixation, relieve pain, improve walking ability and quality of life, and also recover good function of ankle joint.

C1 Titanium Cables Combined with C2 Pedicle Screw-Rod Fixation for Atlantoaxial Instability Not Suitable for Placement of C1 Screws.

OBJECTIVE: We sought to develop a new posterior fusion technique composed of bilateral C1 titanium cables and C2 pedicle screw-rods for treatment of atlantoaxial instability not suitable for C1 screw placement. METHODS: A study was conducted of 18 patients with atlantoaxial instability who had C1 broken screw trajectory or anatomic anomalies. All patients underwent posterior fixation with bilateral C1 titanium cables and C2 pedicle screws. The follow-up period was a minimum 1 year. Clinical outcomes measurements included visual analog scale score for neck pain assessment, the American Spinal Injury Association Impairment Scale and Japanese Orthopaedic Association score for neurologic status and function. According to preoperative computed tomography (CT) reconstruction and CT angiography, the patients selected in this study were not suitable for C1 screw placement. Postoperative plain radiographs and CT reconstruction were performed to evaluate the reduction, bony fusion, and implant position. All outcomes were evaluated at each follow-up. RESULTS: The average clinical follow-up period was 24 months (range 12-36 months). All patients had complete neck pain relief at postoperative 6 months. Their neurologic symptoms had improved significantly at 1-year follow-up. Radiologic outcomes indicated good bony fusion and construction stability in all patients without implant failure at the last follow-up. No neural or vascular complications related to this technique were observed. CONCLUSIONS: Posterior atlantoaxial fixation using C1 titanium cables and C2 pedicle screw-rod construct appears to be an effective and safe technique for treatment of atlantoaxial instability, which could be an alternative method for cases unsuitable for C1 screw placement when using C1-C2 screw fixation.

Influence of miR-30b regulating humoral immune response by genetic difference.

Investigation of genetic difference will be beneficial to researchers to understand the origins and nature of diseases. Previous studies have revealed that L-kynurenine (L-Kyn) level was changed significantly in patient with cancer and that miR-30b play different role in tumor cells and immune cells. Moreover, it has been also conformed that miR-30b involved in the process of L-Kyn-mediated suppression of humoral immune responses induced by lipopolysaccharide (LPS) in human normal B cells separated from volunteers' peripheral blood. Nevertheless, the miR-30b role regulating humoral immune response in B lymphoma cells has been still unclear due to the genetic difference between normal cells and tumor cells. The current study demonstrated that the selected concentration of L-Kyn (100, 1000 µM) significantly reduced the immunoglobulin M secretion induced by LPS when compared with the control group in B lymphoma, CH12.LX, and BCL-1 cells, which had, at least, incomplete dependence on Aryl hydrocarbon receptor, the receptor of L-Kyn. In addition, although L-Kyn (100 µM) significantly attenuated the expression of miR-30b in BCL-1 cells rather than in CH12.LX cells, no significant differences in the strength of L-Kyn-mediated suppression of humoral immune responses induced by LPS were detected by enzyme-linked immunosorbent assay between the LPS (10 µg/ml) + L-Kyn (100 µM) group and the LPS (10 µg/ml) + L-Kyn (100 µM) + miR-30b mimics/miR-30b inhibitor group in CH12.LX and BCL-1 cells, respectively. Further data also showed that mouse Bach2 mRNA was a novel target of miR-30b. These results suggest that genetic difference among cells has a great influence on the miR-30b role in the process of L-Kyn-mediated suppression of humoral immune responses induced by LPS.

Measurement of modal birefringence in optical waveguides based on the Mach-Zehnder interferometer.

A method for measuring the birefringence in planar waveguide circuits is theoretically proposed and validated. The method is based on the Mach-Zehnder interference and by measuring the spectral shift due to orthogonal polarization states. The birefringence of a silica waveguide is measured to be 2.33 × 10(-4) at nearby 1550 nm. In addition, the birefringence variations with the wavelength and its dependence on the external stress are investigated with the proposed method experimentally. The results in measuring birefringence demonstrate a high accuracy with the order of 10(-5), a wide dynamic range from 10(-5) to 10(-3), and a characteristic of multi-wavelength evaluation.