[Analysis on the secondary attack rates of SARS-CoV-2 Omicron variant and the associated factors].

Objective: To evaluate the secondary attack rates of the SARS-CoV-2 Omicron variant and the associated factors. Methods: A total of 328 primary cases and 40 146 close contacts of the SARS-CoV-2 Omicron variant routinely detected in local areas of Jiangsu Province from February to April 2022 were selected in this study, and those with positive nucleic acid test results during 7 days of centralized isolation medical observation were defined as secondary cases. The demographic information and clinical characteristics were collected, and the secondary attack rate (SAR) and the associated factors were analyzed by using a multivariate logistic regression model. Results: A total of 1 285 secondary cases of close contacts were reported from 328 primary cases, with a SAR of 3.2% (95%CI: 3.0%-3.4%). Among the 328 primary cases, males accounted for 61.9% (203 cases), with the median age (Q1, Q3) of 38.5 (27, 51) years old. Among the 1 285 secondary cases, males accounted for 59.1% (759 cases), with the median age (Q1, Q3) of 34 (17, 52) years old. The multivariate logistic regression model showed that the higher SAR was observed in the primary male cases (OR=1.632, 95%CI: 1.418-1.877), younger than 20 years old (OR=1.766, 95%CI: 1.506-2.072),≥60 years old (OR=1.869, 95%CI: 1.476-2.365), infected with the BA.2 strain branch (OR=2.906, 95%CI: 2.388-3.537), the confirmed common cases (OR=2.572, 95%CI: 2.036-3.249), and confirmed mild cases (OR=1.717, 95%CI: 1.486-1.985). Meanwhile, the higher SAR was observed in the close contacts younger than 20 years old (OR=2.604, 95%CI: 2.250-3.015),≥60 years old (OR=1.287, 95%CI: 1.052-1.573) and exposure for co-residence (OR=27.854, 95%CI: 23.470-33.057). Conclusion: The sex and age of the primary case of the Omicron variant, the branch of the infected strain, case severity of the primary case, as well as the age and contact mode of close contacts are the associated factors of SAR.

[Correlation between preoperative inflammatory biomarkers and postoperative pneumonia or long-term prognosis in patients with esophageal cancer after neoadjuvant therapy].

Objective: To examine the correlation between neutrophil-lymphocyte ratio (NLR), lymphocyte-monocyte ratio (LMR) and neutrophil-monocyte ratio (NMR) for postoperative pneumonia or long-term overall survival in patients with esophageal cancer after neoadjuvant therapy. Methods: The clinical data of 137 patients, including 111 males and 26 females, with the age of (M(QR))61(10) years (range: 45 to 75 years), undergoing radical resection of esophageal cancer after neoadjuvant therapy admitted at Department of Thoracic Surgery, West China Hospital from January 2016 to May 2019 were analyzed retrospectively. The blood routine one or two days before surgery and the occurrence of pneumonia after surgery were collected via hospital information system. The absolute count of neutrophils, lymphocytes and monocytes was recorded, to calculate NLR, LMR and NMR. The survival of patients was recorded systematically via follow-up. In the first part, the influencing factors of postoperative inflammation were analyzed, to group the patients into two groups according to the occurrence of postoperative pneumonia. χ2 test, t-test or rank-sum test were conducted for inter-group comparison. In the second part, cutoff values of inflammatory biomarkers were obtained with the receiver operating characteristic (ROC) curve and grouped, with postoperative pneumonia as endpoint criteria. Independent factors correlated with postoperative pneumonia were determined through univariate and multivariate Logistic regression analysis. In the third part, the analysis on prognosis factors was carried on, with the survival as endpoint criteria. Cutoff values of inflammatory biomarkers were obtained with X-Tile software and grouped. The survival analysis was carried on with univariate and multivariate Cox proportional hazards regression model, and the Kaplan-Meier curve was drawn finally. The results of survival analysis were verified by Log-rank test. Results: Median follow-up time was 614 (299) days (range: 382 to 1 612 days). Cutoff values of NLR, LMR, and NMR obtained via the ROC curve were 3.0, 3.9, and 6.2, respectively. According to the multivariate Logistic regression analysis, NLR>3.0 (OR=2.740, 95% CI: 1.221 to 6.152, P=0.015) and LMR>3.9 (OR=0.140, 95% CI: 0.022 to 0.890, P=0.037) were independent prognosis factors for postoperative pneumonia in patients with esophageal cancer after neoadjuvant therapy. Cutoff values of NLR, LMR, and NMR obtained with X-Tile software were 3.3, 4.2, and 7.2, respectively. Through multivariate Cox proportional risk regression analysis, late tumor ypTNM staging (8th AJCC) (HR=2.087, 95% CI:1.079 to 4.038, P=0.029), poor pathologic response (HR=2.251, 95% CI: 1.117 to 4.538, P=0.023), and LMR>4.2 (HR=0.347, 95% CI: 0.127 to 0.946, P=0.039) could be independent prognosis factors for overall survival. Kaplan-Meier survival analysis indicated that the overall survival of patients with LMR ≤4.2 was worse (P=0.002), with the 1-year overall survival rate of 82.9%, and the 1-year overall survival rate of patients with LMR>4.2 was 94.6%. Conclusion: Preoperative LMR ≤3.9 and NLR>3.0 can be considered as independent prognosis factors for postoperative pneumonia, while LMR≤4.2 as one of independent prognosis factors for overall survival.

First Report on the Occurrence of Cucumber mosaic virus on Fragaria ananassa in China.

More than 20 viruses are known to infect strawberry (Fragaria ananassa), and a substantial number of these include new viruses identified since 2000 that can contribute to disease complexes (2). The most serious virus related losses in commercial strawberries are caused by aphid transmitted viruses (3,4,5). A survey was undertaken from 2012 to 2013 to investigate virus prevalence in commercial strawberries in rural areas of Hebei Province around Beijing, China, that were exhibiting virus symptoms. Visual observations revealed that the incidence of virus-like symptoms ranged from 30 to 50% of the plants and these symptoms included yellowing, leaf malformation, sometimes combined with severe stunting and deformed flowers or fruits. Leaf samples were tested for Strawberry vein banding virus (SVBV), Strawberry mottle virus (SMoV), Strawberry mild yellow edge virus (SMYEV), and Strawberry crinkle virus (SCV), which are the four most prevalent aphid-transmitted viruses in single or mixed infections (2). Testing was conducted by RT-PCR using total RNA extracted from fresh symptomatic strawberry leaves (3). SVBV was detected in 58 of 190 samples, but all of the samples tested negative for SMoV, SMYEV, and SCV. Aphids were present on many of the plants, so the samples were tested for Cucumber mosaic virus (CMV) because CMV is prevalent in Beijing gardens and farms, and recently had been shown to infect maize in China (5). This RT-PCR was carried out with the CMV primer pair CM420-F (5'-TGATTCTACCGTGTGGGTGA-3') and CM420-R (5'-CCGTAAGCTGGATGGACAAC-3') to amplify a portion of the capsid protein coding region and the conserved 3'non-translated regions of the genomic RNAs. This test revealed the presence of 43 CMV-positives out of 190 samples, and only 16 of these samples were co-infected with both SVBV and CMV. Samples infected with CMV only had leaf malformations and yellowing, while no CMV was found in symptomless samples. One of the amplified, CMV-specific DNA fragments was sequenced directly from the PCR product and showed 93.8% nucleotide sequence identity and 100% amino acid sequence identity to the CMV subgroup I (GenBank Accession No. D10538) (1). Subsequent ELISA tests for the CMV presence verified the RT-PCR results (Agdia, Elkhart, IN), and transmission electron microscopy observations revealed 28 nm spherical particles characteristic of CMV in strawberry samples tested positive for CMV. However, we were unable to detect either CMV or SVBV in 89 of the 169 samples from symptomatic plants, which suggested possible presence of the other pathogen(s). To the best of our knowledge, this is the first report of natural infections of CMV in strawberry plants. These data suggests that CMV is a potential threat to strawberry production. References: (1) M. Q. K. Andrew et al. Virus taxonomy: IXth Report of the ICTV, 970, Elsevier, 2012. (2) R. R. Martin and I. E. Tzanetakis. Plant Dis. 97:1358, 2013. (3) J. R. Thompson et al. J. Virol. Methods 111:85, 2003. (4) I. E. Tzanetakis et al. Plant Dis. 90:1343, 2006. (5) R. Wang et al. J. Phytopathol. 161: 880, 2013.

[Experimental study for repair of cranial defects with bone marrow stromal cells and modified alginate].

OBJECTIVE: The primary aim of this investigation was to determine whether expanded BMSCs in vitro mixed with modified alginate gelatin could repair critical defects in rats without the addition of exogenous growth or bone morphogenetic factors. METHODS: Bone marrow stem cells from syngeneic rats cultured in vitro and mixed with modified alginate gel to paint the cranial critical size defect. A full-thickness cranial plate defect was created without damage of dura mater. Modified alginate gelatin with or without BMSCs were painted over the cranial defects. Animals being made cranial defect but received no implant served as sham-operated controls. Craniotomy defects were divided into three groups, which included defects left unpainted (group I, n=6), defects painted with modified alginate gelatin alone (group II, n=6), and defects painted with a modified alginate mixed with BMSCs (group III, n=6). A total of 18 implant experiments were carried out, with postsurgical radiographic and histological analysis completed at 12 week. RESULTS: None of the implants exhibited extrusion or infection. Radiographs showed a likely increased calcification in group III, without finally new calcification in group I and in group II. Histology showed that group I and group II were featured by thinning of the bone at the edges of the defect margins with minimal bone growth inward and dense fibrous tissue with rudimentary alginate material spanning the intervenient gap. The results demonstrated that a great amount of new bone in growth took place in BMSCs-alginate group, stemming from cranial defect edges and proceeding inward. CONCLUSION: Transplantation of syngeneic BMSCs with alginate gel can serve as an example of a cell-based treatment for skeletal reformation and would be especially useful for augmenting or regenerating bone in skeletal defects. So syngeneic BMSCs with alginate gel demonstrate a potential technique to regenerate a variety of skeletal defects that occur in different clinical scenaries.

[Expression of platelet derived growth factor receptor-beta in fibroblasts of keloid].

OBJECTIVE: To investigate the expression and distribution of platelet derived growth factor receptor-beta(PDGFR-beta) in normal skin and keloid and to discuss its biological function in keloid formation. METHODS: 1. To detect the expression and distribution of PDGFR-beta in normal skin and keloid tissue by immunohistochemistry; 2. To detect the receptor expression in vitro by Flow cytometry (FCM); 3. To detect the subcellular distribution of receptor by Laser confocal microscope. RESULTS: 1. Immunohistochemistry showed that normal skin and keloid tissue were almost the same in expression but different in distribution of PDGFR-beta; 2. There was more expression of PDGFR-beta in normal fibroblasts than that in keloid fibroblasts in vitro by FCM; 3. Laser confocal microscope revealed that the PDGFR-beta concentrated on the surface of cell membrane in keloid fibroblasts, but in normal skin fibroblasts, the receptors were coagulated on the nuclear membrane and intranucleus. CONCLUSION: Compared with the fibroblasts in vivo, there was a difference of the PDGFR-beta expression in fibroblasts in vitro, more expression of PDGFR-beta in normal fibroblast than that in keloid fibroblast in vitro; and the subcellular distribution of PDGFR-beta was different in normal skin and keloid fibroblasts. The characteristics of the expression and distribution of PDGFR-beta in keloid may contribute to the formation of keloid.

[The experimental study on optimal cell density and formation time of tissue engineered autologous cartilage].

OBJECTIVE: This paper aims to investigate the suitable cell density and the best formation time of tissue engineered autologous cartilage and to provide theoretical basis and parameters for clinical application. METHODS: The chondrocytes isolated from mini swines' ears were mixed with injectable biocompatible matrix (Pluronic), and the density of cell suspensions were 10, 20, 30, 40, 50, 60, 70 x 10(4)/ml. The chondrocyte-polymer constructs were subcutaneously injected into the abdomen of autologous swine. The specimens were observed grossly and histologically after 6 weeks, and investigated the suitable cell density. Then the chondrocyte-polymer constructs with suitable cell density were transplanted into the abdomen of autologous swine and evaluated grossly and histologically in 1, 3, 6, 9, 15 weeks after transplantation to investigate the best formation time of tissue engineered cartilage. RESULTS: The experiments demonstrated that the tissue engineered autologous cartilage was similar to the natural cartilage on animals with normal immune system in histological characteristics. The optimal chondrocyte density is 50 x 10(6)/ml, and the proper harvest time is the sixth week. CONCLUSION: With tissue engineering skills, we have identified the optimal chondrocyte density and the proper harvest time.

[Cultivation of cicatricial fibroblasts and kinetics of growth].

The fibroblasts from normal skin, hypertrophic scar and keloid were cultured in vitro and their growth property was compared. The results showed that there was similar density-dependent inhibition in these three strains, and there were no morphological differences among them. But, in normal skin, fibroblasts were parallelly arranged, showing "fingerprint" and marked polarization, while that in hypertrophic scar and keloid presented crisscross and overlapping with less polarization. All of three strains had same growth kinetics, i.e. the cell growth curve, DNA synthesis and mitosis index were similar during their logarithmic phase.