Characteristics of patients with SARS-COV-2 PCR re-positivity after recovering from COVID-19.

The purpose of this study was to analyse the clinical characteristics of patients with severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) PCR re-positivity after recovering from coronavirus disease 2019 (COVID-19). Patients (n = 1391) from Guangzhou, China, who had recovered from COVID-19 were recruited between 7 September 2021 and 11 March 2022. Data on epidemiology, symptoms, laboratory test results and treatment were analysed. In this study, 42.7% of recovered patients had re-positive result. Most re-positive patients were asymptomatic, did not have severe comorbidities, and were not contagious. The re-positivity rate was 39%, 46%, 11% and 25% in patients who had received inactivated, mRNA, adenovirus vector and recombinant subunit vaccines, respectively. Seven independent risk factors for testing re-positive were identified, and a predictive model was constructed using these variables. The predictors of re-positivity were COVID-19 vaccination status, previous SARs-CoV-12 infection prior to the most recent episode, renal function, SARS-CoV-2 IgG and IgM antibody levels and white blood cell count. The predictive model could benefit the control of the spread of COVID-19.

[PVT1 Promoted the Proliferation and Migration Ability of BMSCs in Glioma C6 Microenvironment].

OBJECTIVE: To investigate the changes in the proliferation and migration ability of bone marrow mesenchymal stem cells (BMSCs) after indirect co-culturing with glioma C6 cells, and to examine the role of plasmacytoma variant translocation 1 gene ( PVT1), a long non-coding RNA (lncRNA), in these changes. METHODS: After separation, cultivation and identification of BMSCs, BMSCs of good growth condition were picked out and indirectly co-cultured with glioma C6 cells in Transwell chambers. These cells are henceforth referred to as the co-culture group. Normal BMSCs cultured separately were the control group. CCK-8 and soft agar colony formation assay were used to examine the proliferation ability of the two groups of cells. Flow cytometry was used to examine the cell cycle. Wound healing assay and Transwell assay were used to explore the migration ability of the cells. Quantitative real-time PCR (qRT-PCR) was used to examine the genetic expression level of PVT1 in the two groups. The above-mentioned tests were repeated after the co-cultured BMSCs were transfected with si- PVT1 (si- PVT1 group) and si-NC (si-NC group). In addition, qRT-PCR was done to evaluate the expression of CyclinD1, a cell cycle protein gene, and matrix metalloproteinases 2 and 9 ( MMP2 and MMP9), the migration-related genes in the si- PVT1 and si-NC transfected co-cultured BMSCs. RESULTS: The BMSCs used in the present study possess the capability of osteogeneic and adipogenic differentiation. Compared with the control group, the co-cultured BMSCs had smaller size, disorderly arrangement and the lack of intercellular contact inhibition. The proliferation and migration ability was significantly enhanced, the proportions of S and G 2 phase cells greatly increased and the expression level of PVT1 was significantly up-regulated ( P<0.05) in the co-cultured group in comparison with those of the control group. When compared with the si-NC group, the si- PVT1 group showed inhibited proliferation and migration ability of the co-cultured BMSCs; the percentage of G 1 phase cells increased, while that of S phase decreased; the expression of PVT1, CyclinD1, MMP2 and MMP9 mRNA also decreased ( P<0.05) in the si- PVT1 group. CONCLUSION: The enhanced proliferation and migration ability of BMSCs in the glioma C6 microenvironment may be associated with the up-regulated expression of PVT1 .

Co-culture with Endothelial Progenitor Cells promotes the Osteogenesis of Bone Mesenchymal Stem Cells via the VEGF-YAP axis in high-glucose environments.

Patients with type 2 diabetes mellitus (T2DM) have a high risk of fracture and experience poor bone healing. In recent years, bone mesenchymal stem cells (BMSCs) and endothelial progenitor cells (EPCs) have become the most commonly used cells in cell therapy and tissue engineering. In this study, we found that high glucose levels had a negative effect on the differentiation of BMSCs and EPCs. Considering that EPCs-BMSCs sheets can provide endothelial cells and osteoblastic cells, we transplanted cell sheets into T2DM rats with bilateral skull defects. The outcomes of the in vivo study revealed that EPCs-BMSCs sheets promoted ossification, which was verified by micro-CT and immunohistochemistry (IHC) analyses. Furthermore, we detected the VEGF content in the culture supernatant using an enzyme-linked immunosorbent assay (ELISA). The results showed that the BMSCs co-cultured with EPCs presented a higher level of VEGF than other cells. To assess the differentiation and migration of BMSCs exposed to VEGF, ALP staining, scratch assay and qRT-PCR analysis were performed. In addition, we used immunofluorescence and western blotting analysis to further explore the related mechanisms. The results showed that cells cultured with VEGF had a stronger actin cytoskeleton and a greater amount of nuclear and total YAP than cells cultured without VEGF. Taken together, our results indicate that co-culture with EPCs could promote the osteogenesis of BMSCs partially via VEGF. Furthermore, YAP and F-actin play important roles in this process.

In vitro synergistic effect of amlodipine and imipenem on the expression of the AdeABC efflux pump in multidrug-resistant Acinetobacter baumannii.

INTRODUCTION: Multidrug-resistant Acinetobacter baumannii (A. baumannii) has become one of the greatest threats worldwide to the therapeutic management of infections. Our previous research confirmed an in vitro synergistic effect of amlodipine and imipenem against A. baumannii, and this study is designed to understand its mechanism. METHODS: Sixty-four non-duplicate A. baumannii isolates were collected and tested for antimicrobial susceptibility by the disk diffusion method. PCR amplification and sequencing were used to identify the presence of the adeB, adeE, adeH, adeJ, abeM and abeS efflux pump genes. The minimal inhibitory concentrations of imipenem, imipenem+amlodipine and imipenem+carbonyl cyanide m-chlorophenyl-hydrazone against these isolates were also determined by the broth microdilution method before and after siRNA silencing of the expression of the adeABC efflux pump. RESULTS: In this study, the combination of amlodipine with imipenem showed synergistic antimicrobial activity against sixty-four A. baumannii isolates when compared with the activity of imipenem alone (p<0.025). In the multidrug-resistant group, AML was more effective than carbonyl cyanide m-chlorophenyl-hydrazone (p<0.001). The efflux pump genes adeB, adeE, adeH, adeJ, abeM and abeS were detected in 100% (4/64), 75% (48/64), 0% (0/64), 100% (64/64), 96.9% (62/64) and 96.9% (62/64) of the sixty-four A. baumannii isolates, respectively. The expression of the adeABC efflux pump genes in the multidrug-resistant group (5.05±19.25) is clearly higher than in the non-multidrug-resistant group (0.17±0.20), (p = 0.01). A gene silencing test verified that the mRNA expression levels of adeABC were decreased at 12 h and increased at 24 h, while the reversal of imipenem resistance by amlodipine disappeared at 12 h and reappeared at 24 h. CONCLUSIONS: The combination of amlodipine with imipenem exhibits an in vitro synergistic antimicrobial effect on multidrug-resistant A. baumannii, which may be due to the inhibition of the AdeABC efflux pump.