Objective To improve the efficiency of skin soft tissueexpansion with the overlapping tissue expansion techniques. Methods From June 2003 to March 2005, 5 cases of skin soft tissue defects were treated with the overlapping tissue expansion techniquetwo overlapped expanders in one soft tissue pocket, which was different from the traditional technique——one expander in one soft tissue pocket. Five patients included 3 males and 2 females, aging from 11 to 28 years. The defect was caused by scar of forearm in 2 cases, by melanotic nevus in 1 caseand by cicatricial baldness in 2 cases. The disease course was 1.5 to 24 years. Thedefect size ranged from 12 cm×5 cm to 13 cm×12 cm. Results Skin expansion process was satisfactory and skin defect was completely repaired with the expanded skin tissue in one operation in 5 cases. After operation, the wound of donor-recipient site healed by first intention. All patients were followed up from 3 to 15months, no contracture, pigmentation and scar occurred at the expanded skin area. The long-term appearances were satisfactory. Conclusion Compare with the traditional tissue expansion techniques, the new overlapping tissue expansion techniques can apparently improve the efficiency of skin soft tissue expansion. Itis suitable for the patients whose expandable skin is limited or no more skin tissue can be dissected near the skin defect and who need more expandable skin torepair skin defect.
ObjectiveTo investigate the effects of smoking combined with intermittent hypoxia on the pathophysiology of lung tissue and thoracic aorta, and the endothelial injury.MethodsTwenty-four rats (SPF, female, six weeks old) were divided randomly into 4 groups (n=6). The control group was given false smoking and normal oxygen exposure, the smoking-exposed group was exposed in smoking, the intermittent hypoxia group was exposed in intermittent hypoxia environment, and the overlap group was exposed to smoking and intermittent hypoxia. After 8 weeks, body weight, right ventricular hypertrophy index (RVHI), the pathological changes of lung tissue and thoracic aorta were measured, and the level of endothelin-1 (ET-1), endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1α (SDF-1α) in serum of rats were evaluated.ResultsRVHI of rats in the smoking-exposed group, intermittent hypoxia group, overlap group were higher than that in the control group. In addition, RVHI in the overlap group was higher than that in the smoking-exposed group, intermittent hypoxia group (all P<0.05). The levels of ET-1, VEGF and SDF-1α in the serum of the smoking-exposed group, intermittent hypoxia group and overlap group were higher than those in the control group, while the level of eNOS was lower than that in the control group, (all P<0.05), the most significant difference was between control group and the overlap group. Pathological observation of lung tissue and thoracic aorta showed obvious emphysema in the smoking-exposed group and overlap group, which was more obvious in the overlap group than that in the smoking-exposed group (all P<0.05). Lung interstitial inflammatory infiltration, bronchial wall lymphocyte hyperplasia and pulmonary fibrosis were shown in different degrees in the smoking-exposed group, intermittent hypoxia group and overlap group, and the pulmonary arteriole wall showed thickening, fibrosis and peripheral inflammatory infiltration also were found in these groups. Thoracic aorta in the smoking-exposed group, intermittent hypoxia group and overlap group showed different degrees of endothelial cell injury, middle membrane thickening, and collagen fiber hyperplasia. The pathological features of the overlap group were most obvious compared to the other two groups.ConclusionsSmoking and intermittent hypoxia exposure can lead to different degrees of lung tissue and vascular endothelial injury and decrease of vascular endothelial protective factors in rats, resulting in dysfunction of vascular endothelial cells, which leads to the structural remodeling of pulmonary arterioles and aorta, such as thickening, fibrosis, etc. Combined smoking and intermittent hypoxia exposure can lead to more serious pathological damage.
This study introduced the inverse probability weight and overlap weight by propensity score and how to test the balance and estimate the effect after weighting. Four R packages that can be used for propensity score weight analysis were introduced and compared.
Objective To compare the ability of three propensity score weighting methods to balance the covariates and the advantages and disadvantages to estimate the treatment effects when dealing with multiple treatment data under different sample sizes. Methods Monte Carlo simulation was used to generate data sets and the advantages and disadvantages of balancing covariates and estimating the treatment effects of three propensity score weighting methods, Logistic-IPTW, Logistic-OW and GBM-OW were compared. The evaluation index of covariate equilibrium level was the absolute standard mean difference. The evaluation indexes of effect estimation included the point estimate of treatment effect, root mean square error and confidence interval coverage. Results Compared with Logistic-IPTW and Logistic-OW, GBM-OW was better in effect estimation and had a smaller root mean square error in five scenarios where covariates were related to treatment factors and outcome variables with different varying degrees of complexity. In terms of covariate equilibrium, all three methods had good effects. GBM-OW method performed better when the overlap of propensity score distribution of multiple treatment data was relatively low and covariables had increasingly complex nonlinear relationships with treatment factors and outcome variables. Conclusion When dealing with multiple treatment data, GBM-OW method has advantages over the other two methods when there is nonlinearity and/or interaction between covariates and treatment factors and outcome variables. Using this method, the effect estimation is closer to the real value, which is a better choice.
ObjectiveTo investigate the extent of overlap between Chinese systematic reviews (SRs) and Cochrane SRs in the field of stroke. MethodsThe CNKI, WanFang Data, CBM and Cochrane Library databases were searched to collect Chinese SRs and Cochrane SRs in the field of stroke published from 2012 to 2022. By extracting population (P), intervention (I), comparison (C), and outcome (O) of all interventional SRs in the stroke field to analyse the extent of overlap of SRs. The basic information and research information of SRs with overlapping PICOs were further extracted to conduct descriptive analysis. ResultsA total of 1 303 SRs were included, involving 1 192 Chinese SRs and 111 Cochrane SRs in the field of stroke. The overlapping analysis found that 128 Chinese SRs overlapped with 29 (26.1%) of the 111 Cochrane SRs. Most (127/128, 99.2%) Chinese SRs were published later than Cochrane SRs. The year of publication of overlapping SRs showed a trend of increasing year by year. ConclusionThe SR work carried out by scholars in China has the problem of overlapping studies that cannot be ignored, and the lack of strict regulation and guidance in methods such as registration, protocol writing, and literature search has resulted in a great waste of resources. It is necessary to further strengthen regulatory constraints and guidance, adhere to problem orientation and quality awareness, strengthen SR training, and reduce overlapping research.
The overlap of literature in umbrella reviews can affect the reliability and accuracy of research conclusions, leading to results with a higher risk of bias. Therefore, it becomes crucial to assess the degree of overlapping and how to handle it. In order to avoid redundant calculations and reduce the risk of bias, researchers need to quantify the degree of literature overlap and adopt corresponding processing strategies. This paper provides a detailed introduction to the calculation methods of overlapping and different strategies for handling overlapping, aiming to provide a reference and guidance for domestic scholars' understanding and application of this method.