Abstract: Viral shedding of SARS-CoV-2 is a continuous dynamic process, which can be divided into latent stage, initial stage, peak stage and decreasing stage according to the characteristics of viral shedding. After being infected with SARS-CoV-2, the infected person generally stays in the latent period for 1-3 days, which is characterized by continuous negative nucleic acid test results and no infectiousness, and the risk of infection for close contacts is very low. At the initial stage of viral shedding is characterized by a rapid decline in the Ct value of nucleic acid tests in a short time, and clinical symptoms gradually appear. The infectiousness of the infected person gradually increases during this period, and the risk of infection for close contacts also gradually increases, but it is still in the early stage of infection, the possibility of viral shedding is low, and the risk of infection of secondary close contacts is low. The peak of viral shedding is characterized by low Ct value in nucleic acid test and obvious clinical symptoms; during this period, the infected person is the most infectious, and the risk of infection of the contact is the highest, so the scope of close contacts should be expanded appropriately. The decreasing period is characterized by the gradual increase of Ct value of nucleic acid test and the gradual disappearance of clinical symptoms; during this period, the infectiousness of the infected person gradually decreases to disappear. In an outbreak, an infected person in the decreasing phase is more likely to be an early infected person in the transmission chain. If infected individuals in the decreasing phase are found in an area without a SARS-CoV-2 epidemic, it suggests that the local outbreak epidemic has been spreading for some time and may be larger in scale. According to the characteristics of viral shedding, risk personnel can be determined more scientifically and accurately, so as to minimize the risk and reduce the waste of epidemic prevention resources.

OBJECTIVEMalignant transformation of epithelial cell frequently coincides with loss of E-cadherin. Here we study the expression of Snail and E-cadherin and correlate their expression with cell differentiation and in vitro invasion.

METHODSThe expression and localization of Snail and E-cadherin were studied by Northern blot and laser confocal microscopy in two normal cell lines (MDCK, NIH 3T3) and six carcinoma cell lines (A431, MCF-7, MDA-MB-453, HepG2, MDA-MB-435s, MDA-MB-231). Boyden chamber assay was done to detect the invasive ability of cells in vitro.

RESULTSSnail mRNA and protein were detected in fibroblasts NIH 3T3 and poorly differentiated carcinoma cell lines HepG2, MDA-MB-435s and MDA-MB-231. On the contrary, E-cadherin mRNA and protein were detected in normal epithelial cell line MDCK and well differentiated carcinoma cell lines A431 and MDA-MB-453. In MCF-7 cells, Snail and E-cadherin expressions were revealed both at mRNA and protein levels. The cells with higher expression of Snail had stronger ability of invasion than those with lower expression of Snail.

CONCLUSIONThere is an inverse correlation between Snail and E-cadherin expressions and their expressions are correlated with cell differentiation and tumor invasiveness.

3T3 Cells ; metabolism ; Animals ; Cadherins ; biosynthesis ; genetics ; Cell Differentiation ; Cell Line ; Cell Line, Tumor ; Cell Transformation, Neoplastic ; metabolism ; Dogs ; Epithelial Cells ; cytology ; metabolism ; Humans ; Mice ; Neoplasm Invasiveness ; Snail Family Transcription Factors ; Transcription Factors ; biosynthesis ; genetics

OBJECTIVETo evaluate the value and limitations of multislice spiral CT in diagnosing coronary artery stenoses.

METHODSA total of 65 patients with known or suspected coronary artery disease were examined by multislice spiral CT (retrospectively ECG-gating; 0.5 s rotation; one-sector reconstruction algorithm; intravenous contrast agent) and the results were compared with quantitative coronary angiography.

RESULTSIn the 889 coronary artery segments of 65 patients, 795 could be evaluated by CT (89.4%), 148 out of 167 coronary artery segments with significant stenoses (> or = 50% reduction of vessel diameter) were correctly detected by CT, 597 out of 628 coronary artery segments with normal or mild stenosis (< 50% reduction of vessel diameter) were correctly detected by CT. These values correspond to a sensitivity of 88.6%, specificity of 95.1%, positive predictive value of 82.7%, and negative predictive value of 96.9% for the detection of significant coronary artery stenosis by CT. Adding the 23 coronary artery segments with significant stenosis which could not be judged by CT, the sensitivity of CT for diagnosing coronary stenosis was 77.9%. In the 795 evaluable coronary artery segments, 78 out of 86 coronary artery segments with high-grade stenosis (> or = 75% reduction of vessel diameter) were correctly detected by CT, 692 of 709 coronary artery segments with normal or mild stenosed (< 75% reduction of vessel diameter) were correctly detected by CT. These values correspond to a sensitivity of 90.7%, specificity of 97.6%, positive predictive value of 82.1%, and negative predictive value of 98.9% for the detection of high-grade coronary artery segments stenosis by CT. Adding 13 coronary artery segments with high-grade stenosis which could not be judged by CT, the sensitivity was 78.8%.

CONCLUSIONMultislice spiral CT permits the visualization of significant coronary artery stenosis with high accuracy in case of sufficient image quality.

Adult ; Aged ; Coronary Angiography ; methods ; Coronary Stenosis ; diagnosis ; diagnostic imaging ; physiopathology ; Electrocardiography ; Female ; Humans ; Male ; Middle Aged ; Predictive Value of Tests ; Tomography, Spiral Computed ; methods

BACKGROUNDCoronary artery in-stent restenosis (ISR) and late stent thrombosis remain as important complications of stenting. The inflammation reactions to sirolimus and paclitaxel-eluting stents were investigated in a swine stenosis model induced by interleukin (IL)-1β.

METHODSMini pigs (n = 12; 2-3 months old and weighing 25-30 kg) were subjected to thoracotomy. Segments (10 mm) of the mid left anterior descending coronary artery and left circumflex coronary artery were exposed and aseptically wrapped with a cotton mesh soaked with IL-1β (5 µg). After 2 weeks, the animals were anesthetized and quantitative coronary arteriography (QCA) was performed. The stenosis sites were randomized into three groups for stent insertion: a sirolimus-eluting stent (SES) group (Firebird(TM), n = 7), a paclitaxel-eluting stent (PES) group (TAXUS(TM), n = 9), and a bare-metal stent (BMS) group (YINYITM, Dalian Yinyi Biomaterials Development Co., Ltd, China, n = 8). The three different stents were randomly implanted into stenosis segments. Expression of monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-α), P-selectin and vascular cell adhesion molecule-1 (VCAM-1) was determined by reverse transcription-coupled polymerase chain reaction (RT-PCR).

RESULTSQCA showed severe stenosis in IL-1β treated segments. The SES and PES groups showed lower 1-month angiographic late lumen loss (LLL) within the stent and the lesion compared with BMS (P < 0.05) by follow-up QCA. The SES showed lower LLL than that of PES in reducing 1-month inflammation lesions in pigs by follow-up QCA ((0.15 ± 0.06) mm vs. (0.33 ± 0.01) mm, P < 0.0001). The neointimal hyperplasia areas in SES and PES showed lower than those of BMS (SES (11.6 ± 1.7) mm(2), PES (27.2 ± 1.6) mm(2) vs. BMS (76.2 ± 1.3) mm(2), P < 0.0001). The mRNA expression of MCP-1 by RT-PCR in SES and PES showed lower than that of BMS at 30 days after stenting (SES 0.20 ± 0.03, PES 0.48 ± 0.49 vs. BMS 0.58 ± 0.07, P < 0.05). Levels of VCAM-1 in SES were significantly lower than those of PES and BMS (SES 0.35 ± 0.08 vs. PES 0.65 ± 0.13, BMS 0.70 ± 0.06, P < 0.05). Histochemical immunostaining of vessel walls showed lower inflammatory chemokine MCP-1 expression in the SES and PES groups compared with BMS.

CONCLUSIONSESs were superior in reducing 1-month angiographic LLL in inflammation lesions in pigs, strongly suggesting that SESs can suppress inflammatory reactions in ISR at multiple points.

Angioplasty, Balloon, Coronary ; adverse effects ; Animals ; Coronary Restenosis ; prevention & control ; Drug-Eluting Stents ; adverse effects ; Inflammation ; prevention & control ; Interleukin-1beta ; pharmacology ; Male ; Paclitaxel ; administration & dosage ; Sirolimus ; administration & dosage ; Swine

Background and Objectives: Osteoblasts are derived from bone marrow mesenchymal stem cells (BMMSCs) and playimportant role in bone remodeling. While our previous studies have investigated the cell subtypes and heterogeneity in osteoblasts and BMMSCs separately, cell-to-cell communications between osteoblasts and BMMSCs in vivo in humans have not been characterized. The aim of this study was to investigate the cellular communication between human primary osteoblasts and bone marrow mesenchymal stem cells. Methods: and Results: To investigate the cell-to-cell communications between osteoblasts and BMMSCs and identifynew cell subtypes, we performed a systematic integration analysis with our single-cell RNA sequencing (scRNA-seq) transcriptomes data from BMMSCs and osteoblasts. We successfully identified a novel preosteoblasts subtype which highly expressed ATF3, CCL2, CXCL2 and IRF1. Biological functional annotations of the transcriptomes suggested that the novel preosteoblasts subtype may inhibit osteoblasts differentiation, maintain cells to a less differentiated status and recruit osteoclasts. Ligand-receptor interaction analysis showed strong interaction between mature osteoblasts and BMMSCs. Meanwhile, we found FZD1 was highly expressed in BMMSCs of osteogenic differentiation direction. WIF1 and SFRP4, which were highly expressed in mature osteoblasts were reported to inhibit osteogenic differentiation. We speculated that WIF1 and sFRP4 expressed in mature osteoblasts inhibited the binding of FZD1 to Wnt ligand in BMMSCs, thereby further inhibiting osteogenic differentiation of BMMSCs. Conclusions Our study provided a more systematic and comprehensive understanding of the heterogeneity of osteogenic cells. At the single cell level, this study provided insights into the cell-to-cell communications between BMMSCs and osteoblasts and mature osteoblasts may mediate negative feedback regulation of osteogenesis process.

Objectives: To analyze and understand the risk factors related to HIV new infections among men who have sex with men (MSM). Methods: A longitudinal observational study among MSM was conducted to collect information on HIV related behaviors and sero-conversion. Univariate and multivariate generalized estimating equations (GEE) were used to discuss the risk factors for HIV new infection. Results: A total number of 4 305 MSM were followed during 2013-2015. Among those self-reported MSM who are seeking partners on the Interner tended to have higher proportion on receptive anal intercourse and consistent condom use during anal intercourse than the subgroups seeking their partners in gay bars or bathrooms. HIV incidence among followed MSM during the study period appeared as 4.3/100 person years, with adjusted RR (aRR) of HIV infection for receptive anal intercourse as group 2.20 (95% CI: 1.49-3.24) times than that of insertion anal intercourse group. Those who used rush-poppers (aRR=1.55, 95% CI: 1.10-2.17), unprotected anal intercourse (aRR=2.24, 95%CI: 1.62-3.08), and those with syphilis infection (aRR=2.95, 95%CI: 2.00-4.35) were also risk factors for HIV new infections. After controlling other factors, the relationship between the ways of seeking partners and HIV new infection was not statistical significant. Conclusion: Risk factors for HIV new infection among MSM appeared complex and interactive, suggesting that further studies are needed to generate tailored strategies for the prevention of HIV epidemic among MSM population.
Adult ; Cohort Studies ; HIV Infections/diagnosis* ; Homosexuality, Male ; Humans ; Incidence ; Male ; Risk Factors ; Risk-Taking ; Sexual Behavior ; Sexual Partners ; Sexual and Gender Minorities ; Surveys and Questionnaires ; Unsafe Sex

Objective:To observe the stability of severe acute respiratory syrdrome coronavirus （SARS-CoV-2） in cell cultures at different temperatures so as to provide basic data and scientific basis for the research and control of COVID-19 epidemic. Methods:The Vero E6 cells inoculated with SARS-CoV-2. According to TCID₅₀， SARS-CoV-2 with different dilution （10^-1， 10^-3， 10^-5， 10^-6）were stored at 37 °C， 22.5 °C， and 4 °C for one to seven days， and then infectious titer was determined by micro cytopathogenic effect assay， observing cytopathic effect （CPE）， and real-time fluorescence quantitative testing. Results:SARS-CoV-2 was stable under 4 °C. The infectivity of high concentration （10^-1 dilution） under 22.5 °C for seven days gradually decreased， while lower concentration completely lost infectivity after one day. The virus lost infectivity when stored at 37 °C for more than one day. Conclusion:SARS-CoV-2 is highly stable at 4 °C， sensitive to heat， and related to virus concentration.