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1.
Cell Mol Biol (Noisy-le-grand) ; 66(6): 71-75, 2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-33040788

RESUMO

In this study, we investigated the effect of latanoprost on the expression of TGF- ß1 and Wnt / ß - Catenin signal pathway in the choroid of form-deprivation myopia model rats. Forty rats were randomly divided into two groups: the control group and the FDM model group. Each group had 20 rats. The FDM model group was established by feeding latanoprost daily for 28 days. 15 rats in each group were used to measure the length of the ocular axis and the level of TGF-ß1 in choroidal tissue; the remaining 5 rats in each group were used for choroidal fibroblast culture. After modeling, the rats were killed, the length of the ocular axis was measured with a vernier caliper, and the level of TGF - ß1 protein and mRNA in the choroidal tissue of each group were measured with RT-PCR method. Results showed that compared with the control group, there was a significant difference in the axial length of the FDM model group (P< 0.05). There was a significant difference in the expression of TGF- ß1 protein and mRNA between the two groups (P<0.05). The cultured cells were identified as choroidal fibroblasts by immunocytochemistry. There was no significant difference (P>0.05) in the comparison of GSK3 ß protein in choroidal fibroblasts of rats in each group. TGF-ß 1 and APC protein in FDM group were significantly lower than those in the control group (P<0.05), while dcl3, p21-gsk3 ß and ß - Catenin proteins were significantly higher (P<0.05), and there was no significant difference (P>0.05) in the ratio of various indexes protein in FDM + ddk1 group and the comparison of TGF - ß1 and APC protein in FDM + ddk1 group and FDM group The expression of dcl3, p21-gsk3 ß and ß - Catenin decreased significantly (P<0.05). There was no significant difference in the expression of GSK3 ß mRNA in the choroidal fibroblasts of each group (P>0.05). The expression of TGF - ß 1 and APC mRNA in FDM group was significantly lower than that in the control group (P<0.05), while the expression of dcl3, p21-gsk3 ß and ß-catenin mRNA in FDM + ddk1 group was significantly higher than that in the control group (P<0.05) >In FDM + ddk1 group, TGF-ß 1 and APC mRNA were significantly lower than those in FDM group (P<0.05), while dcl3, p21-gsk3 ß and ß-Catenin mRNA were significantly higher (P<0.05).

2.
Sci Rep ; 10(1): 16107, 2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-32999359

RESUMO

We first reported a phenomenon of cross-resistance to vancomycin (VCM) and daptomycin (DAP) in methicillin-resistant Staphylococcus aureus (MRSA) in 2006, but mechanisms underlying the cross-resistance remain incompletely understood. Here, we present a follow-up study aimed to investigate genetic determinants associated with the cross-resistance. Using 12 sets of paired DAP susceptible (DAPS) and DAP non-susceptible (DAPR) MRSA isolates from 12 patients who had DAP therapy, we (i) assessed susceptibility to DAP and VCM, (ii) compared whole-genome sequences, (iii) identified mutations associated with cross-resistance to DAP and VCM, and (iv) investigated the impact of altered gene expression and metabolic pathway relevant to the cross-resistance. We found that all 12 DAPR strains exhibiting cross-resistance to DAP and VCM carried mutations in mprF, while one DAPR strain with reduced susceptibility to only DAP carried a lacF mutation. On the other hand, among the 32 vancomycin-intermediate S. aureus (VISA) strains isolated from patients treated with VCM, five out of the 18 strains showing cross-resistance to DAP and VCM carried a mprF mutation, while 14 strains resistant to only VCM had no mprF mutation. Moreover, substitution of mprF in a DAPS strain with mutated mprF resulted in cross-resistance and vice versa. The elevated lysyl-phosphatidylglycerol (L-PG) production, increased positive bacterial surface charges and activated cell wall (CW) synthetic pathways were commonly found in both clinical isolates and laboratory-developed mutants that carry mprF mutations. We conclude that mprF mutation is responsible for the cross-resistance of MRSA to DAP and VCM, and treatment with DAP is more likely to select for mprF-mediated cross-resistance than is with VCM.

3.
Nat Biomed Eng ; 2020 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-33046865

RESUMO

Therapeutic leukaemia vaccines have shown modest potency. Here, we show that the co-encapsulation of a leukaemia-associated epitope peptide highly expressed in leukaemia patients and of the immune checkpoint inhibitor anti-programmed-cell-death-protein-1 (anti-PD-1) in degradable poly(lactic acid) microcapsules resulted in the sustained release of the peptide and of the antibody, which led to the recruitment of activated antigen-presenting cells to the injection site, their uptake of the peptide and the transportation of the anti-PD-1 antibody to lymph nodes, enhancing the expansion of epitope-specific T cells and the activation of cytotoxic T cells. After single subcutaneous injections of vaccine formulations with different epitope peptides, mice bearing leukaemia xenografts derived from humanized cell lines or from primary cells from patients showed better therapeutic outcomes than mice receiving repeated injections of free antigen, antibody and a commercial adjuvant. The sustained release of a tumour-associated peptide and of anti-PD-1 may represent a generalizable strategy for boosting antitumour immune responses to leukaemia.

4.
Comput Math Methods Med ; 2020: 8894478, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33029195

RESUMO

Heat shock proteins (HSPs) are ubiquitous in living organisms. HSPs are an essential component for cell growth and survival; the main function of HSPs is controlling the folding and unfolding process of proteins. According to molecular function and mass, HSPs are categorized into six different families: HSP20 (small HSPS), HSP40 (J-proteins), HSP60, HSP70, HSP90, and HSP100. In this paper, improved methods for HSP prediction are proposed-the split amino acid composition (SAAC), the dipeptide composition (DC), the conjoint triad feature (CTF), and the pseudoaverage chemical shift (PseACS) were selected to predict the HSPs with a support vector machine (SVM). In order to overcome the imbalance data classification problems, the syntactic minority oversampling technique (SMOTE) was used to balance the dataset. The overall accuracy was 99.72% with a balanced dataset in the jackknife test by using the optimized combination feature SAAC+DC+CTF+PseACS, which was 4.81% higher than the imbalanced dataset with the same combination feature. The Sn, Sp, Acc, and MCC of HSP families in our predictive model were higher than those in existing methods. This improved method may be helpful for protein function prediction.

5.
Biomed Res Int ; 2020: 1942849, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33029492

RESUMO

Purpose: To study the pharmacokinetics of the 6 alkaloids (aconitine, mesaconitine, hypaconitine, benzoylaconine, benzoylmesaconine, and benzoylhypaconine) in raw Aconiti Kusnezoffii Radix (Caowu) (RC) and Chebulae Fructus- (Hezi-) processed Caowu (HC) in the rats being, respectively, administrated with RC and HC in the dosage forms of powder and decoction and to demonstrate the mechanism of detoxification of HC. Methods: The rats were randomly divided into 4 groups and, respectively, given RC powder, HC powder, RC decoction, and HC decoction by intragastric administration. The contents of the 6 alkaloids in the plasma of the rats were detected at different time points by the UPLC-MS/MS method, and DAS 3.2.7 software was used to calculate, compare, and analyze the detected pharmacokinetic parameters. Results: Compared with those of the RC powder, the values of AUC0-t and C max of the HC powder were all reduced, whereas the values of t 1/2z and T max were mostly increased. Compared with those of the RC powder, the values of AUC0-t , C max, and t 1/2z of the RC decoction were decreased and the value of T max of the RC decoction was increased. Compared with those of the RC decoction, the values of AUC0-t , t 1/2z , and C max of the diester diterpenoid alkaloids of the HC decoction were all increased. However, there was no marked difference between the pharmacokinetic parameters of the HC powder and the HC decoction. Conclusions: A decrease in the level of absorption and in the rate of elimination of the alkaloids can be detected when HC is administrated in the dosage form of the powder, explaining that in traditional Mongolian medicine (TMM), the purpose of using HC in the dosage forms of pills and powder is for decreasing the toxicity and prolonging the efficacy duration of HC. Decocting can greatly decrease the plasma concentration of the diester diterpenoid alkaloids in RC and increase their rate of elimination. The influence of decocting on RC is greater than that on HC, explaining the rationality of the steaming and boiling methods for processing Caowu and the rationality of boiling Caowu for a longer time beforehand in preparing an herb decoction containing Caowu in TCM.

6.
Am J Emerg Med ; 2020 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-33036854

RESUMO

INTRODUCTION: The efficacy of intravenous thiamine to treat septic shock remains controversial. We conduct a systematic review and meta-analysis to explore the impact of intravenous thiamine on treatment efficacy of septic shock. METHODS: We have searched PubMed, EMbase, Web of science, EBSCO, and Cochrane library databases through June 2020 and included randomized controlled trials (RCTs) assessing the effect of intravenous thiamine on septic shock. This meta-analysis was performed using the random-effect model. RESULTS: Four RCTs were included in the meta-analysis. Overall, compared with control group in patients with septic shock, intravenous thiamine revealed no substantial impact on mortality (odd ratio [OR] = 0.87; 95% confidence interval [CI) = 0.62 to 1.21; P = 0.40), lactate change (standard mean difference [SMD] = 0.04; 95% CI = -0.28 to 0.35; P = 0.82), Sequential Organ Failure Assessment (SOFA) change (SMD = 0.02; 95% CI = -0.18 to 0.21; P = 0.87), intensive care unit (ICU) stay (SMD = -0.02; 95% CI = -0.33 to 0.30; P = 0.90) or renal replacement therapy (OR = 0.47; 95% CI = 0.07 to 3.15; P = 0.43). CONCLUSIONS: Intravenous thiamine showed no benefit over placebo in treating patients with septic shock.

7.
Materials (Basel) ; 13(20)2020 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-33081179

RESUMO

As a representative of the third generation of advanced high strength steel, the quenching and partitioning steel has excellent potential in automobile manufacturing. The characterization and analysis of the mechanical properties and microstructure of the quenching and partitioning steel during deformation is an effective way to explore the microstructure evolution and transformation-induced plasticity effects of complex phase steels. The relationship between the microstructure morphology and mechanical properties of a 1180 MPa-grade quenching and partitioning steel was investigated through interrupted uniaxial tensile tests plus quasi-situ electron backscatter diffraction measurements. A mixture of ferrite, martensite, and retained austenite was observed in the microstructure. It was found that the volume fraction of global retained austenite decreased linearly with the increase of displacement (0 mm-1.05 mm). The evolution of the retained austenite with typical crystal direction ranges with deformation was characterized. Results show that the orientation (111) and (311) account for the highest proportion of retained austenite grains in the undeformed sample and the mechanical stability of the (311) retained austenite grains is the best. Moreover, the retained austenite grains rotated significantly in the early stage of the specimen deformation process (around yielding), and the work hardening of the specimen was weak at this stage, simultaneously.

8.
World J Clin Cases ; 8(19): 4311-4319, 2020 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-33083390

RESUMO

BACKGROUND: Transanal minimally invasive surgery (TAMIS) is a good choice for resection of rectal neoplasms. Endoscopic mucosal resection (EMR) is also widely used in the treatment of benign rectal tumors such as rectal polyps and rectal adenomas. However, no studies have compared the outcome of TAMIS and EMR. AIM: To compare the short-term outcomes after TAMIS and EMR for rectal carcinoid and benign tumors (including rectal polyps and adenomas). METHODS: From January 2014 to January 2019, 44 patients who received TAMIS and 53 patients who received EMR at The Fifth People's Hospital of Shanghai were selected. Primary outcomes (surgical-related) were operating time, blood loss, length of postoperative hospital stay, rate of resection margin involvement and lesion fragmentation rate. The secondary outcomes were complications such as hemorrhage, urinary retention, postoperative infection and reoperation. RESULTS: No significant differences were observed in terms of blood loss (12.48 ± 8.00 mL for TAMIS vs 11.45 ± 7.82 mL for EMR, P = 0.527) and length of postoperative hospital stay (3.50 ± 1.87 d for TAMIS vs 2.72 ± 1.98 d for EMR, P = 0.065) between the two groups. Operating time was significantly shorter for EMR compared with TAMIS (21.19 ± 9.49 min vs 49.95 ± 15.28 min, P = 0.001). The lesion fragmentation rate in the EMR group was 22.6% (12/53) and was significantly higher than that (0%, 0/44) in the TAMIS group (P = 0.001). TAMIS was associated with a higher urinary retention rate (13.6%, 6/44 vs 1.9%, 1/53 P = 0.026) and lower hemorrhage rate (0%, 0/44 vs 18.9%, 10/53 P = 0.002). A significantly higher reoperation rate was observed in the EMR group (9.4%, 5/53 vs 0%, 0/44 P = 0.036). CONCLUSION: Compared with EMR, TAMIS can remove lesions more completely with effective hemostasis and lower postoperative hemorrhage and reoperation rates. TAMIS is a better choice for the treatment of rectal carcinoids.

9.
Biosens Bioelectron ; 171: 112707, 2020 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-33049565

RESUMO

In traditional homogeneous electrochemical sensing system, methylene blue was stricken with nonspecific intercalation and weak stability, inevitably distorting the diagnosis results. Given the unique catalytic activity of oxidase- and peroxidase-like nanozymes, it is interesting to develop a nanozyme-based homogeneous electrochemical biosensor. Whereas, the preparation of nanozymes with dual enzyme-like activities and two dimensional (2D) morphology is a great challenge. Herein, a soft template-directed wet chemical approach was proposed for preparation of 2D MnO2 nanoflakes, in which the morphology can be easily tuned by the template dosage. Interestingly, not only the oxidase-like activity was discovered, but 2D MnO2 nanoflakes also display a significant peroxidase-like activity. Noticeably, 2D MnO2 nanoflakes exhibit superior response to single stranded deoxyribonucleic acid (ssDNA) over double stranded DNA in the aspect of binding and catalytic activity, which triggers a highly sensitive homogeneous electrochemical detection of microRNA. This study about finding nanozymes with dual enzyme-like activities and ssDNA with inhibiting effect will set up a new avenue to extend the application range of nanozymes and throws a new light on the development of higher-performance electrochemical biosensors.

10.
Clin Neurol Neurosurg ; 198: 106181, 2020 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-33022525

RESUMO

OBJECTIVE: The loss of dopaminergic cells and excessive iron deposition in some deep brain nuclei are associated with the pathophysiology of PD, and different clinical subtypes may indicate different pathological processes. This study was designed to investigate the relationships between regional iron in the cardinal subcortical nuclei and different clinical subtypes. PATIENTS AND METHODS: Nine Arkinetic/Rigid-dominant Parkinson's disease (PDAR) patients, eight Tremor-dominant (PDTD)patients and 10 matched healthy controls were recruited for this study. The iron content in 8 cardinal subcortical nuclei was measured through SWI sequence scanning (3.0 T), and different patterns of iron deposition were analyzed not only between the PD patients and HC groups but also between the different clinical subtypes. RESULTS: Compared with the healthy controls, the iron content in the substantia nigra pars compacta(SNc), substantia nigra pars reticulata(SNr) from both the severe and milder side in PD groups were significantly increased (P < 0.01 and P < 0.02 for SNc; both P < 0.01 for SNr), and the iron content in the GP of both the severe and milder side of the PDAR patients was significantly increased compared with the PDTD patients (P < 0.01 and P = 0.02, respectively) CONCLUSION: SWI is a very good technique for the in vivo assessment of subcortical nucleus iron content, and abnormal deposition of iron in the SNc and SNr is an obvious characteristic in PD patients. Furthermore, our data indicates that PDAR patients have higher iron content in the GP than PDTD patients and HCs, indicating that abnormal iron deposition in GP is related to the phenotype of Akinetic/Rigid in PD patients.

11.
Sci Rep ; 10(1): 17479, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-33060660

RESUMO

Genome engineering is a rapidly evolving field that benefits from the availability of different tools that can be used to perform genome manipulation tasks. We describe here the development of the Flp-TAL recombinases that can target genomic FRT-like sequences in their native chromosomal locations. Flp-TAL recombinases are hybrid enzymes that are composed of two functional modules: a variant of site-specific tyrosine recombinase Flp, which can have either narrow or broad target specificity, and the DNA-binding domain of the transcription activator-like effector, TAL. In Flp-TAL, the TAL module is responsible for delivering and stabilizing the Flp module onto the desired genomic FRT-like sequence where the Flp module mediates recombination. We demonstrate the functionality of the Flp-TAL recombinases by performing integration and deletion experiments in human HEK-293 cells. In the integration experiments we targeted a vector to three genomic FRT-like sequences located in the ß-globin locus. In the deletion experiments we excised ~ 15 kilobases of DNA that contained a fragment of the integrated vector sequence and the neighboring genome sequence. On average, the efficiency of the integration and deletion reactions was about 0.1% and 20%, respectively.

12.
J Med Virol ; 2020 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-33090532

RESUMO

While the coronavirus disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) continues to wreak havoc, there is little known about the susceptibility of the livestock and companion animals relative to humans. Here, we explore the susceptibility of companion and agricultural animals, in the light of the existing information on natural infections, experimental infections, serosurveillance, and in vitro protein-homology binding interaction studies of the SARS-CoV-2 with the proposed receptor Angiotensin-converting enzyme 2 (ACE2) from diverse animal species. This article is protected by copyright. All rights reserved.

13.
Elife ; 92020 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-33021199

RESUMO

Neuroregeneration is a dynamic process synergizing the functional outcomes of multiple signaling circuits. Channelrhodopsin-based optogenetics shows the feasibility of stimulating neural repair but does not pin down specific signaling cascades. Here, we utilized optogenetic systems, optoRaf and optoAKT, to delineate the contribution of the ERK and AKT signaling pathways to neuroregeneration in live Drosophila larvae. We showed that optoRaf or optoAKT activation not only enhanced axon regeneration in both regeneration-competent and -incompetent sensory neurons in the peripheral nervous system but also allowed temporal tuning and proper guidance of axon regrowth. Furthermore, optoRaf and optoAKT differ in their signaling kinetics during regeneration, showing a gated versus graded response, respectively. Importantly in the central nervous system, their activation promotes axon regrowth and functional recovery of the thermonociceptive behavior. We conclude that non-neuronal optogenetics targets damaged neurons and signaling subcircuits, providing a novel strategy in the intervention of neural damage with improved precision.

14.
BMC Pediatr ; 20(1): 477, 2020 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-33050899

RESUMO

BACKGROUND: Epilepsy is one of the most common neurological problems among children. The aim of this survey was to assess the knowledge and attitude among preschool staff in Shanghai regarding epilepsy. METHODS: A cross-sectional survey was carried out among the staff at selected preschools. A stratified random sampling method was first used to identify suitable subjects. Data were obtained using a self-completed questionnaire. A standardized collection of demographic information was performed, and participants were given a questionnaire about their knowledge and attitudes regarding epilepsy. RESULTS: A total of 1069 subjects completed the questionnaire. In this survey, 387 (36.2%) staff members had previously participated in related training. 17.6% of teachers knew how to provide appropriate first aid for seizures. Correct responses regarding first aid for seizures, such as laying the person on his or her side (24.9%), moving harmful objects out of the way (20.7%), protecting the head (36.1%), waiting until the seizure ends (7.9%), and dialing the emergency number (40.1%), were low. The staff members had different attitudes towards children with epilepsy: some subjects had a positive attitude, some had a negative attitude. CONCLUSIONS: The level of first-aid knowledge among preschool staff in Shanghai relevant to epilepsy was low. There is an urgent need to educate staff about epilepsy and appropriate first-aid practices for seizures.

15.
Artigo em Inglês | MEDLINE | ID: mdl-33026144

RESUMO

There is a need for biosensing systems that can be operated at the point-of-care (POC) for disease screening and diagnostics and health monitoring. In spite of this, simple to operate systems with the required analytical sensitivity and specificity in clinical samples, using a sample-in-answer-out approach, remain elusive. Reported here is an electrochemical bio-barcode assay (e-biobarcode assay) that integrates biorecognition with signal transduction using molecular (DNA/protein) machines and signal readout using nanostructured electrodes. The e-biobarcode assay eliminates multistep processing and uses a single step for analysis following sample collection into the reagent tube. A clinically relevant performance for the analysis of prostate specific antigen (PSA) in undiluted and unprocessed human plasma: a log-linear range of 1 ng mL-1 -200 ng mL-1 and a LOD of 0.4 ng mL-1 , was achieved. The e-biobarcode assay offers a realistic solution for biomarker analysis at the POC.

16.
BMC Cancer ; 20(1): 949, 2020 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-33008330

RESUMO

BACKGROUND: Breast cancer is the leading cause of cancer mortality in women worldwide. Therefore, it is of great significance to identify the biological mechanism of tumorigenesis and explore the development of breast cancer to achieve a better prognosis for individuals suffering from breast cancer. MicroRNAs (miRNAs) have become a hot topic in cancer research, but the underlying mechanism of its involvement in cancer remains unclear. METHODS: The miRNA profile between breast cancer stem cells (BCSCs, CD44+CD24-/low) and control MCF-7 breast cancer cells was obtained in a previous study. Based on biological analysis, miR-20b-5p was hypothesized to be a key factor due to the malignant behavior of BCSCs. Then, agomir-20b-5p and antagomir-20b-5p were transfected into MCF-7 and T47D breast cancer cells to detect cell migration, wound healing and proliferation, and lentivirus vectors silencing or overexpressing miR-20b-5p were transfected into T47D-CSCs to detect proliferation and apoptosis. The effect of miR-20b-5p on xenograft growth was investigated in vivo by transfection of a lentivirus-overexpression vector into T47D cells. The target genes were predicted by the online programs picTar, miRanda and TargetScan and verified by dual luciferase assay, and changes in protein expression were detected by western blot. RESULTS: MiR-20b-5p had the highest degree in both the miRNA-gene network and miRNA-GO network to regulate BCSCs. Overexpression of miR-20b-5p significantly promoted the migration and wound healing ability of MCF-7 cells and T47D cells compared with the control (P < 0.05). In addition, miR-20b-5p facilitated the proliferation of MCF-7 cells and T47D-CSCs (P < 0.05) and inhibited the apoptosis of T47D-CSCs (P < 0.05). Moreover, miR-20b-5p promoted xenograft growth compared with the control group (P < 0.05). Accordingly, potential targets of both CCND1 and E2F1 were predicted by bioinformatics analysis. MiR-20b-5p directly targeted both CCND1 and E2F1 in a dual luciferase assay, while antagomir-20b-5p downregulated the protein levels of CCND1 and E2F1. CONCLUSIONS: Oncogenic miR-20b-5p was confirmed to promote the malignant behaviors of breast cancer cells and BCSCs. The underlying mechanism lies in that miR-20b-5p overall enhanced both CCND1 and E2F1 targets via bidirectional regulation probably involving direct downregulation and indirect upregulation.

18.
Nanotechnology ; 31(50): 505403, 2020 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-33021223

RESUMO

In this paper, we report a simple hydrothermal method for preparation of ultrathin carbon-coated CdS (CdS@C) nanobelts. The CdS@C nanobelts show superior electrochemical properties as an anode material for Li-ion batteries. The optimized CdS@C composites deliver a reversible capacity around 910 mAhg-1 and 48 mAhg-1 at 0.1 Ag-1 and 30.0 Ag-1, respectively. Moreover, the optimized nanobelts are also potential materials for Na storage. A stable capacity around 240 mAhg-1 is obtained at 0.1 Ag-1, even after 100 cycles.

19.
Sci Rep ; 10(1): 16907, 2020 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-33037239

RESUMO

Staphylococcus aureus strains that are susceptible to the ß-lactam antibiotic oxacillin despite carrying mecA (OS-MRSA) cause serious clinical problems globally because of their ability to easily acquire ß-lactam resistance. Understanding the genetic mechanism(s) of acquisition of the resistance is therefore crucial for infection control management. For this purpose, a whole-genome sequencing-based analysis was performed using 43 clinical OS-MRSA strains and 100 mutants with reduced susceptibility to oxacillin (MICs 1.0-256 µg/mL) generated from 26 representative OS-MRSA strains. Genome comparison between the mutants and their respective parent strains identified a total of 141 mutations in 46 genes and 8 intergenic regions. Among them, the mutations are frequently found in genes related to RNA polymerase (rpoBC), purine biosynthesis (guaA, prs, hprT), (p)ppGpp synthesis (relSau), glycolysis (pykA, fbaA, fruB), protein quality control (clpXP, ftsH), and tRNA synthase (lysS, gltX), whereas no mutations existed in mec and bla operons. Whole-genome transcriptional profile of the resistant mutants demonstrated that expression of genes associated with purine biosynthesis, protein quality control, and tRNA synthesis were significantly inhibited similar to the massive transcription downregulation seen in S. aureus during the stringent response, while the levels of mecA expression and PBP2a production were varied. We conclude that a combination effect of mecA upregulation and stringent-like response may play an important role in acquisition of ß-lactam resistance in OS-MRSA.

20.
Cell Mol Immunol ; 2020 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-33037400

RESUMO

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been redetected after discharge in some coronavirus disease 2019 (COVID-19) patients. The reason for the recurrent positivity of the test and the potential public health concern due to this occurrence are still unknown. Here, we analyzed the viral data and clinical manifestations of 289 domestic Chinese COVID-19 patients and found that 21 individuals (7.3%) were readmitted for hospitalization after detection of SARS-CoV-2 after discharge. First, we experimentally confirmed that the virus was involved in the initial infection and was not a secondary infection. In positive retests, the virus was usually found in anal samples (15 of 21, 71.4%). Through analysis of the intracellular viral subgenomic messenger RNA (sgmRNA), we verified that positive retest patients had active viral replication in their gastrointestinal tracts (3 of 16 patients, 18.7%) but not in their respiratory tracts. Then, we found that viral persistence was not associated with high viral titers, delayed viral clearance, old age, or more severe clinical symptoms during the first hospitalization. In contrast, viral rebound was associated with significantly lower levels of and slower generation of viral receptor-binding domain (RBD)-specific IgA and IgG antibodies. Our study demonstrated that the positive retest patients failed to create a robust protective humoral immune response, which might result in SARS-CoV-2 persistence in the gastrointestinal tract and possibly in active viral shedding. Further exploration of the mechanism underlying the rebound in SARS-CoV-2 in this population will be crucial for preventing virus spread and developing effective vaccines.

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