Objective: To investigate the protective effects and mechanisms of acellular nerve allografts (ANA) on motor neurons in the spinal cord anterior horn of sciatic nerve injury ( SNI) rats . Methods: SPF grade male SD rats were randomly divided into normal , model , ANA-bridged (bridge group) , and autologous nerve transplantation groups (autograft group) , with 6 rats in each group . The SNI rat model was established using the right sciatic nerve clamp method for 10 mm . In the bridge group , the ANA was bridged to the two severed ends of the injured sciatic nerve , and in the autograft group , the autologous nerves were flipped head to tail and then bridged to the two se- vered ends . A spectrophotometer was applied to determine the DNA content in normal nerves and ANA . The foot- print test was used to determine the sciatic nerve function index (SFI) of the rats in each group , the wet weight ra- tio of the anterior tibialis muscle was calculated . The morphology and structure of the anterior horn motor neurons of the spinal cord of each group were observed by HE staining. The immunofluorescence and Western blot were used to detect Apaf-1 , Caspase-3 , Bcl-2 , Bax , and Cyt-C proteins expression in the L4-6 segment of the spinal cord . Results: The DNA content in the ANA prepared in this study was significantly lower than that in normal nerves (P < 0. 05) . Compared with the normal group , the SFI and wet weight ratio of the anterior tibialis muscle were re- duced in the model group (P < 0. 001) ; compared with the model group , both SFI and wet weight ratio of the ante- rior tibialis muscle significantly increased in the bridge group and the autografts group ( P < 0. 05 , P < 0. 001) , and the SFI and wet weight ratio of the anterior tibialis muscle in the autograft group were higher than those in the bridge group (P < 0. 001 , P < 0. 01) . The results of HE staining showed that the motor neurons in the anterior horn of the spinal cord of the normal group were structurally intact and had clear cytosolic boundaries; the neurons in the model group were lysed and necrotic , with blurred cytosolic boundaries; the neurons in the bridge group were less lysed and necrotic , but the nuclear translocation phenomenon could still be seen; the neurons in the autograft group were morphologically and structurally intact with clear cytosolic boundaries . Compared with the normal group , the expression of Apaf-1 , Caspase-3 , Bax and Cyt-C proteins significantly increased in the model group (P < 0. 001 , P < 0. 01 , P < 0. 01 , P < 0. 05) . Compared with the model group , the expression of Apaf-1 , Caspase- 3 , Bax , and Cyt-C proteins significantly decreased (P < 0. 001 , P < 0. 05 , P < 0. 05 , P < 0. 05) ; but the expres- sion of Bcl-2 protein significantly increased in the bridge group and the autograft group (P < 0. 05) . The expression of Apaf-1 , Caspase-3 , Bax and Cyt-C proteins in the autografts group was lower than that in the bridge group (P < 0. 001 , P < 0. 05 , P < 0. 05 , P < 0. 05) . Conclusion ANA can exert a protective effect on motor neurons in the anterior horn of the spinal cord of SNI rats by improving the morphology and structure of neurons , increasing the ex- pression of Bcl-2 protein , but decreasing the expression of Cyt-C , Bax , Caspase-3 , and Apaf-1 proteins in the spi- nal cord . The mechanism of ANA may be related to the Bcl-2/Cyt-C/Apaf-1-mediated mitochondrial apoptosis sig- naling pathway .

Objective:To explore the clinical characteristics and predictive factors for plastic bronchitis (PB) in children with severe Mycoplasma pneumoniae pneumonia (SMPP). Methods:A retrospective cohort enrolled children with a clinical diagnosis of SMPP who were treated at the Department of Respiratory Medicine of Tianjin Children′s Hospital Machang District from January 1, 2018, to October 31, 2023. According to the bronchoscopy and pathological examination results, the patients were divided into 142 cases in the PB group and 274 cases in the non-PB group. The clinical manifestations, laboratory data, imaging findings, and treatments were analyzed.Mann-Whitney U test and Chi-square test were used to analyze the differences between the two groups, and multivariate Logistic regression was used to analyze the risk factors. The receiver operating characteristic (ROC) curve was used to explore the predictive value of PB in SMPP. Results:Among 416 SMPP children, there were 197 males and 219 females; PB group 142 cases, non-PB group 274 cases, the age of disease onset was (6.9±2.9) years and (6.6±2.8) years in the PB group and the non-PB group respectively. The incidence of wheezing symptoms, hypoxemia, heat peak >40 ℃, the duration of fever, neutrophil-lymphocyte ratio, mean platelet volume, C-reactive protein, procalcitonin, interleukin-6, alanine transaminase, aspartate aminotransferase and ferritin were higher in the PB group (16 cases (11.3%) vs. 15 cases (5.5%), 14 cases (9.9%) vs. 12 cases (4.4%), 57 cases (40.1%) vs. 67 cases (24.5%), 10 (8, 12) vs. 9 (8, 12) d, 6.1 (4.1, 13.1)×10 9vs. 5.0 (3.7, 6.8)×10 9/L, 10.2 (9.6, 10.8) vs. 9.4 (8.9, 10.1) fl, 33.4 (16.0, 67.5) vs. 23.0 (10.4, 56.1) mg/L, 0.24 (0.12, 0.48) vs. 0.16 (0.09, 0.31) μg/L, 39.9 (25.1, 81.4) vs. 31.3 (18.3, 59.3) ng/L, 16.0 (12.0, 29.0) vs. 14.0 (10.0, 24.3) U/L, 38.5 (28.0, 52.5) vs. 33.0 (25.0, 44.0) U/L, 233 (136, 488) vs. 156 (110, 293) μg/L, χ2=4.55, 4.79, 11.00, Z=2.25, 4.00, 6.64, 2.76, 2.98, 3.09, 2.22, 2.62, 4.18, all P<0.05). Multivariate Logistic regression analysis showed that the dyspnea ( OR=2.97, 95% CI 1.35-6.55, P=0.007), the diminution of respiration ( OR=2.40, 95% CI 1.27-4.52, P=0.006), neutrophil-lymphocyte ratio (NLR) ( OR=2.07, 95% CI 1.71-2.51, P<0.001), lactate dehydrogenase (LDH) ( OR=1.01, 95% CI 1.00-1.01, P<0.001), mean platelet volume/platelet count (MPV/PLT) ( OR=1.39, 95% CI 1.13-1.71, P=0.002), pleural effusion ( OR=2.23, 95% CI 1.21-4.13, P=0.011),≥2/3 lobe consolidation ( OR=1.84, 95% CI 1.04-3.00, P=0.039) and atelectasis ( OR=1.98, 95% CI 1.02-3.48, P=0.044) were independent predictors of PB in children with SMPP. ROC curve analysis showed that the cut-off values for NLR, LDH and MPV/PLT in the diagnosis of PB were 2.79 (sensitivity 0.89, specificity 0.69, area under the curve (AUC)=0.86, P<0.001), 474 U/L (sensitivity 0.63, specificity 0.65, AUC=0.70, P=0.003) and 0.04 (sensitivity 0.75, specificity 0.53, AUC=0.68, P=0.005) respectively. Children in the PB group had longer hospital stays and corticosteroid treatment course than those in the non-PB group, the proportion of children in the PB group who received bronchoscopy treatment twice or more was higher (9 (8, 12) vs. 8 (6, 10) d, 7 (5, 8) vs. 6 (5, 7) d, 128 cases (90.1%) vs. 218 cases (79.6%), 106 cases (74.7%) vs. 54 cases (19.7%), Z=6.70, 5.06, χ2=7.48, 119.27, all P<0.05). Conclusions:The dyspnea, respiration diminution, NLR level elevation (>2.79) and pleural effusion were predictive factors for PB in children with SMPP. This provides a basis for the early identification of PB in children with SMPP.