Publications by authors named "Xinqiang Liu"

29 Publications

  • Page 1 of 1

Hierarchically hybrid biocoatings on Ti implants for enhanced antibacterial activity and osteogenesis.

Colloids Surf B Biointerfaces 2021 Aug 29;204:111802. Epub 2021 Apr 29.

Department of Orthodontics, The Affiliated Hospital of Qingdao University, Qingdao, 266003, China; School of Stomatology, Qingdao University, Qingdao, 266003, China; Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao, 266021, China. Electronic address:

Titanium (Ti) is widely applied as bone-anchoring implants in dental and orthopedic applications owing to its superior mechanical characteristics, high corrosion resistance, and excellent biocompatibility. Nevertheless, Ti-based implants with the deficiencies of insufficient osteoinduction and associated infections can result in implant failure, which significantly limits its applications in some cases. In this work, hierarchically hybrid biocoatings on Ti implants are developed by gradual incorporation of polydopamine (PDA), ZnO nanoparticles (nZnO), and chitosan (CS)/nanocrystal hydroxyapatite (nHA) via oxidative self-polymerization, nanoparticle deposition, solvent casting and evaporation methods for enhancing their antibacterial activity and osteogenesis. The modification of PDA on porous reticular Ti substrates greatly reduces the surface roughness, wettability, protein adsorption, and provides high adhesion to the deposited nZnO. Further, incorporating nZnO on PDA-coated Ti surfaces affects the surface structure and wettability, significantly inhibits the growth of both Staphylococcus aureus and Escherichia coli. Moreover, the CS/nHA-doped coating on the nZnO-modified Ti surfaces remarkably improves cytocompatibility and enhances the osteogenic differentiation of MC3T3-E1 cells by upregulating the protein expression of alkaline phosphatase. This work offers a promising alternative for developing Ti implants with long-lifetime bioactivity to achieve strong antibacterial ability and enhanced bone formation for potential dental/orthopedic applications.
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http://dx.doi.org/10.1016/j.colsurfb.2021.111802DOI Listing
August 2021

Maf1 Ameliorates Sepsis-Associated Encephalopathy by Suppressing the NF-B/NLRP3 Inflammasome Signaling Pathway.

Front Immunol 2020 23;11:594071. Epub 2020 Dec 23.

Department of Critical Care Medicine, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China.

Background: The NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome has been identified as an important mediator of blood-brain-barrier disruption in sepsis-associated encephalopathy (SAE). However, no information is available concerning the critical upstream regulators of SAE.

Methods: Lipopolysaccharide (LPS) was used to establish an model of blood-brain barrier (BBB) disruption and an model of SAE. Disruption of BBB integrity was assessed by measuring the expression levels of tight-junction proteins. NLRP3 inflammasome activation, pro-inflammatory cytokines levels, and neuroapoptosis were measured using biochemical assays. Finally, the FITC-dextran Transwell assay and Evan's blue dye assay were used to assess the effect of Maf1 on LPS-induced endothelial permeability and

Results: We found that Maf1 significantly suppressed the brain inflammatory response and neuroapoptosis induced by LPS and . Notably, Maf1 downregulated activation of the NF-B/p65-induced NLRP3 inflammasome and the expression of pro-inflammatory cytokines. In addition, we found that Maf1 and p65 directly bound to the gene promoter region and competitively regulated the function of NLRP3 in inflammations. Moreover, overexpression of NLRP3 reversed the effects of p65 on BBB integrity, apoptosis, and inflammation in response to LPS. Our study revealed novel role for Maf1 in regulating NF-B-mediated inflammasome formation, which plays a prominent role in SAE.

Conclusions: Regulation of Maf1 might be a therapeutic strategy for SAE and other neurodegenerative diseases associated with inflammation.
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http://dx.doi.org/10.3389/fimmu.2020.594071DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7785707PMC
June 2021

Elevated intracranial pressure induces IL‑1β and IL‑18 overproduction via activation of the NLRP3 inflammasome in microglia of ischemic adult rats.

Int J Mol Med 2021 01 3;47(1):183-194. Epub 2020 Nov 3.

Department of Emergency and Critical Care Medicine, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong 510080, P.R. China.

Elevated intracranial pressure (ICP) is one of the most common complications following an ischemic stroke, and has implications for the clinical and neurological outcomes. The aim of the present study was to examine whether elevated ICP may increase IL‑1β and IL‑18 secretion by activating the NOD‑like receptor protein 3 (NLRP3) inflammasome in microglia of ischemic adult rats. Sprague‑Dawley rats that underwent middle cerebral artery occlusion were used for assessment of ICP. Reactive oxygen species (ROS) production was detected, and western blotting and immunofluorescence staining were used to determine the expression levels of Caspase‑1, gasdermin D‑N domains (GSDMD‑N), IL‑1β and IL‑18 in microglial cells. ICP levels were significantly increased, which was accompanied by ROS overproduction, in the brain tissue following ischemia‑reperfusion (IR) injury in rats. Treatment with 10% hypertonic saline by intravenous injection significantly reduced the ICP and ROS levels of the rats. Furthermore, high pressure (20 mmHg) combined with oxygen‑glucose deprivation (OGD) treatment resulted in increased ROS production in BV‑2 microglial cells compared with those subjected to OGD treatment alone in vitro. Elevated pressure upregulated the expression of Caspase‑1, GSDMD‑N, IL‑18 and IL‑1β in IR‑treated or OGD‑treated microglia both in vivo and in vitro. More importantly, Caspase‑1, GSDMD‑N, IL‑18 and IL‑1β expression in microglia was significantly downregulated when elevated pressure was reduced or removed. These results suggested that elevated ICP‑induced IL‑1β and IL‑18 overproduction via activation of the NLRP3 inflammasome by ischemia‑activated microglia may augment neuroinflammation.
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http://dx.doi.org/10.3892/ijmm.2020.4779DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7723509PMC
January 2021

[Mechanism of resveratrol on ameliorating the cognitive dysfunction induced by sepsis associated encephalopathy in rats].

Zhonghua Wei Zhong Bing Ji Jiu Yi Xue 2020 Oct;32(10):1189-1193

Department of Emergency and Critical Care Medicine, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Guangzhou 510080, Guangdong, China. Corresponding author: Zeng Hongke, Email:

Objective: To explore the mechanism of resveratrol on ameliorating the cognitive dysfunction induced by sepsis associated encephalopathy (SAE) in rats.

Methods: The 12 weeks old male Sprague-dawley (SD) male rats were randomly divided into sham group, sepsis group and resveratrol group, with 30 rats in each group. The rat model of sepsis was made by injecting LPS (10 mg/kg) into tail vein. The rats in sham group was given the same amount of normal saline (NS). After LPS injection, resveratrol (8 mg×kg×d) was intraperitoneally injected once daily for 2 days in the resveratrol group; the same amount of NS was given to the sepsis group and sham group. At 24 hours after model establishment, the cognitive function of the experimental rats was assessed by the Morris water maze test. The blood-brain barrier (BBB) permeability was evaluated by the brain water content (BWC) and Evans blue (EB) test. The protein expressions of matrix metalloproteinase 9 (MMP-9), Occludin and Claudin-5 in cortical tissue were detected by Western Blot. Double immunofluorescence was used to verify the co-localization of MMP-9 protein and the marker protein of astrocyte GFAP in the cortical tissue of rats.

Results: Compared with the sham group, the escape latency in the sepsis group was significantly longer [48-hour escape latency (s): 56.56±6.43 vs. 36.62±3.32, 72-hour escape latency (s): 57.72±7.23 vs. 26.46±4.24, both P < 0.01], the BWC and extravasation of EB were increased [BWC: (84.56±2.03)% vs. (76.82±2.22)%, EB (μg/g): 17.56±2.28 vs. 6.25±1.36, both P < 0.01], the expression of MMP-9 protein was increased (MMP-9/β-actin: 0.73±0.01 vs. 0.24±0.01, P < 0.01), the protein expressions of Occludin and Claudin-5 were decreased (Occludin/β-actin: 0.45±0.02 vs. 0.86±0.04, Claudin-5/β-actin: 0.62±0.03 vs. 0.96±0.05, both P < 0.01). At the same time, the co-localization expression of MMP-9 protein and the astrocytes of the cortical were increased [MMP-9 fluorescence intensity (AU): 38.66±4.26 vs. 17.23±3.04, MMP-9 positive cells: (26.92±1.77)% vs. (12.82±1.46)%, both P < 0.01]. Compared with the sepsis group, the escape latency in resveratrol group was significantly shorter [48-hour escape latency (s): 41.42±6.27 vs. 56.56±6.43, 72-hour escape latency (s): 33.46±7.17 vs. 57.72±7.23, both P < 0.01], the BWC and extravasation of EB were decreased [BWC: (77.15±2.27)% vs. (84.56±2.03)%, EB (μg/g): 7.74±1.88 vs. 17.56±2.28, both P < 0.01], the expression of MMP-9 protein was decreased (MMP-9/β-actin: 0.25±0.01 vs. 0.73±0.01, P < 0.01), the protein expressions of Occludin and Claudin-5 were increased (Occludin/β-actin: 0.82±0.03 vs. 0.45±0.02, Claudin-5/β-actin: 0.92±0.04 vs. 0.62±0.03, both P < 0.01). At the same time, the co-localization expression of MMP-9 protein and the astrocytes of the cortical were decreased [MMP-9 fluorescence intensity (AU): 19.44±4.37 vs. 38.66±4.26, MMP-9 positive cells: (13.11±1.29)% vs. (26.92±1.77)%, both P < 0.01].

Conclusions: Resveratrol can inhibit the expression of MMP-9 protein in the astrocytes of the cortical cortex of rats, and then reduce the degradation of tight junction proteins of Occludin and Claudin-5, thereby reducing BBB permeability and eventually ameliorate the cognitive dysfunction induced by SAE.
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http://dx.doi.org/10.3760/cma.j.cn121430-20200720-00531DOI Listing
October 2020

A 2-kb Mycovirus Converts a Pathogenic Fungus into a Beneficial Endophyte for Brassica Protection and Yield Enhancement.

Mol Plant 2020 10 29;13(10):1420-1433. Epub 2020 Sep 29.

State Key Laboratory of Agricultural Microbiology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei Province 430070, China; The Provincial Key Lab of Plant Pathology of Hubei Province, Huazhong Agricultural University, Wuhan, China. Electronic address:

Mycoviruses are viruses that infect fungi, and hypovirulence-associated mycoviruses have the potential to control fungal diseases. However, it is unclear how mycovirus-mediated hypovirulent strains live and survive in the field, and no mycovirus has been applied for field crop protection. In this study, we found that a previously identified small DNA mycovirus (SsHADV-1) can convert its host, Sclerotinia sclerotiorum, from a typical necrotrophic pathogen to a beneficial endophytic fungus. SsHADV-1 downregulates the expression of key pathogenicity factor genes in S. sclerotiorum during infection. When growing in rapeseed, the SsHADV-1-infected strain DT-8 significantly regulates the expression of rapeseed genes involved in defense, hormone signaling, and circadian rhythm pathways. As a result, plant growth is promoted and disease resistance is enhanced. Field experiments showed that spraying DT-8 at the early flowering stage can reduce the disease severity of rapeseed stem rot by 67.6% and improve yield by 14.9%. Moreover, we discovered that SsHADV-1 could also infect other S. sclerotiorum strains on DT-8-inoculated plants and that DT-8 could be recovered from dead plants. These findings suggest that the mycoviruses may have the ability to shape the origin of endophytism. Our discoveries suggest that mycoviruses may influence the origin of endophytism and may also offer a novel strategy for disease control in which mycovirus-infected strains are used to improve crop health and release mycoviruses into the field.
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http://dx.doi.org/10.1016/j.molp.2020.08.016DOI Listing
October 2020

CRISPR-Cas12a-Assisted Genome Editing in .

Front Bioeng Biotechnol 2020 26;8:698. Epub 2020 Jun 26.

College of Life Sciences, Shanghai Normal University, Shanghai, China.

U32 is an industrial producer of rifamycin SV, whose derivatives have long been the first-line antimycobacterial drugs. In order to perform genetic modification in this important industrial strain, a lot of efforts have been made in the past decades and a homologous recombination-based method was successfully developed in our laboratory, which, however, requires the employment of an antibiotic resistance gene for positive selection and did not support convenient markerless gene deletion. Here in this study, the clustered regularly interspaced short palindromic repeat (CRISPR) system was employed to establish a genome editing system in U32. Specifically, the subsp. () gene was first integrated into the U32 genome to generate target-specific double-stranded DNA (dsDNA) breaks (DSBs) under the guidance of CRISPR RNAs (crRNAs). Then, the DSBs could be repaired by either the non-homologous DNA end-joining (NHEJ) system or the homology-directed repair (HDR) pathway, generating inaccurate or accurate mutations in target genes, respectively. Besides of , the present work may also shed light on the development of CRISPR-assisted genome editing systems in other species of the genus.
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http://dx.doi.org/10.3389/fbioe.2020.00698DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7332547PMC
June 2020

Hypercapnia exacerbates the disruption of the blood‑brain barrier by inducing interleukin‑1β overproduction in the blood of hypoxemic adult rats.

Int J Mol Med 2020 Aug 14;46(2):762-772. Epub 2020 May 14.

Department of Emergency and Critical Care Medicine, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong 510080, P.R. China.

Refractory hypoxemia is the main symptom of acute respiratory distress syndrome (ARDS). Low tidal volume ventilation is routinely applied in clinical practice to correct hypoxemia, which aims to prevent ventilator‑induced lung injury. However, this ventilation strategy inevitably leads to hypercapnia. Our previous study demonstrated that hypercapnia aggravated cognitive impairment in hypoxemic rats; however, the underlying mechanism remains unclear. The aim of the present study was to investigate whether hypercapnia exacerbates the blood‑brain barrier (BBB) disruption through inducing interleukin (IL)‑1β overproduction in the blood of hypoxemic rats. The BBB permeability in a rat model of hypercapnia/hypoxemia was evaluated. The levels of IL‑1β in the blood of rats and human whole‑blood cultures were assessed. The expression of IL‑1 receptor 1 (IL‑1R1), phosphorylated IL‑1R1‑associated kinase (p‑IRAK‑1) and tight junctional proteins in cerebral vascular endothelial cells was examined in vitro and in vivo. In addition, IL‑1Ra, an IL‑1 receptor antagonist, was used to determine whether hypercapnia affects tight junctional protein expression in hypoxic cerebral vascular endothelial cells through inducing IL‑1β overproduction. It was observed that hypercapnia alone did not disrupt the BBB, but aggravated the damage to the BBB integrity in hypoxemic rats. Hypercapnia increased IL‑1β expression in the blood of hypoxemic rats as well as in hypoxic human whole‑blood cultures. IL‑1R1 and p‑IRAK‑1 expression was increased, while that of tight junctional proteins was reduced by hypercapnia in hypoxemic cerebral vascular endothelial cells in vitro and in vivo. Additionally, the expression of tight junctional proteins was markedly increased following treatment with IL‑1Ra. These results suggest that hypercapnia‑induced IL‑1β overproduction in the hypoxemic blood may decrease tight junctional protein expression in cerebrovascular endothelial cells via the IL‑1R1/p‑IRAK‑1 pathway, further disrupting BBB integrity, and eventually resulting in increased BBB permeability.
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http://dx.doi.org/10.3892/ijmm.2020.4604DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7307827PMC
August 2020

[Effect of hypercapnia on the clinical prognosis and severity of infection in patients with severe community-acquired pneumonia].

Zhonghua Wei Zhong Bing Ji Jiu Yi Xue 2020 May;32(5):564-569

Department of Emergency and Critical Care Medicine, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Guangzhou 510080, Guangdong, China. Corresponding author: Zeng Hongke, Email:

Objective: To investigate the effect of hypercapnia at admission on the clinical prognosis and the severity of infection in patients with severe community-acquired pneumonia (SCAP).

Methods: The clinical data of 219 SCAP patients admitted to the department of emergency and critical care medicine of Guangdong Provincial People's Hospital from December 2017 to November 2019 were retrospectively analyzed. Based on the partial pressure of arterial carbon dioxide (PaCO) within 1 day after admission, the patients were divided into hypocapnia group [HO group, PaCO < 35 mmHg (1 mmHg = 0.133 kPa)], normal carbonation group (NC group, PaCO 35-45 mmHg) and hypercapnia group (HC group, PaCO > 45 mmHg). The clinical parameters of patients, such as gender, age, underlying diseases, white blood cell (WBC), procalcitonin (PCT), C-reactive protein (CRP), interleukin-6 (IL-6), pH value and lactate (Lac) within 1 day after admission were reviewed. The oxygenation index (PaO/FiO), pneumonia severity index (PSI) score and acute physiology and chronic health evaluation II (APACHE II) score were evaluated. The change tendencies of each index on day 1, day 3, and day 5 after admission were observed subsequently. Meanwhile, the rate of invasive mechanical ventilation (IMV), length of hospital stays and 28-day mortality among three groups were compared. Kaplan-Meier survival analysis was performed to assess the 28-day cumulative survival rate of patients with SCAP among three groups. Multivariate Logistic regression analysis was used to screen the risk factors of IMV and 28-day death in patients with SCAP.

Results: Compared with the HO group (n = 68) and NC group (n = 72), the HC group (n = 79) had higher proportion of preexisting comorbid chronic obstructive pulmonary disease (COPD) and PSI score, lower PCT, CRP, IL-6, and pH values. Compared with the HO group and NC group, there were smaller improvement trends on the levels of WBC, PCT, CRP, IL-6, PaO/FiO and Lac at day 3 and day 5 as compared with day 1 in the HC group. On the 5th day after admission, the levels of WBC, PCT, CRP, IL-6, and Lac in the HC group were significantly higher than those in the HO group and NC group [WBC (×10/L): 18.33±1.44 vs. 10.89±2.37, 11.15±1.74; PCT (μg/L): 5.04±1.18 vs. 3.46±0.87, 3.58±0.83; CRP (mg/L): 78.43±7.17 vs. 54.24±4.97, 57.93±5.39; IL-6 (ng/L): 75.35±11.92 vs. 60.11±10.27, 57.88±12.34; Lac (mmol/L): 4.36±1.24 vs. 0.78±0.39, 0.86±0.64; all P < 0.01], and the lowest in PaO/FiO was found in the HC group as compared with the HO and NC groups (mmHg: 171.31±6.73 vs. 226.68±7.36, 225.93±6.92, both P < 0.01). Compared with the HO group and NC group, the HC group had highest proportion of IMV (29.1% vs. 22.1%, 22.2%, both P < 0.01) and 28-day mortality (26.6% vs. 13.2%, 13.9%, both P < 0.01). Even when the patients with COPD were excluded from the analysis, the differences persisted among the groups. Kaplan-Meier survival analysis suggested that HC group had a higher 28-day cumulative survival rate as compared with the HO and NC groups (Log-Rank test: χ = 4.976, P = 0.026; χ = 4.629, P = 0.031). Multivariate Logistic regression analysis showed that IL-6, PSI score and hypercapnia within 1 day and PCT on the 5th day after admission were the independent risk factors of requiring IMV and 28-day death in patients with SCAP [odds ratio (OR) were 0.325, 1.229, 1.396, 1.313, respectively, all P < 0.01]. Even when patients with COPD were excluded from the analysis, the above results had not been changed.

Conclusions: Hypercapnia at admission was associated with higher proportion of IMV and 28-day mortality in patients with SCAP, which may be related to its early suppression of inflammation and then increment of infection.
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http://dx.doi.org/10.3760/cma.j.cn121430-20200122-00099DOI Listing
May 2020

Hypercapnia Exacerbates the Blood-Brain Barrier Disruption Via Promoting HIF-1a Nuclear Translocation in the Astrocytes of the Hippocampus: Implication in Further Cognitive Impairment in Hypoxemic Adult Rats.

Neurochem Res 2020 Jul 23;45(7):1674-1689. Epub 2020 Apr 23.

The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, Guangdong, People's Republic of China.

Hypercapnia in combination with hypoxemia is usually present in severe respiratory disease in the intensive care unit (ICU) and can lead to more severe cognitive dysfunction. Increasing evidence has indicated that the compromised blood-brain barrier (BBB) in the hippocampus in hypoxemia conditions can result in cognitive dysfunction. However, the role and underlying mechanism of hypercapnia in the BBB disruption remains poorly known. A rat model of hypercapnia was first established in this study by intubation and mechanical ventilation with a small-animal ventilator. After this, the cognitive function of the experimental rats was assessed by the Morris water maze test. The BBB permeability was evaluated by the Evans Blue (EB) test and brain water content (BWC). Western blot analysis was carried out to detect the protein expressions of total and nuclear hypoxia-inducible factor-1α (HIF-1α), matrixmetalloproteinase-9 (MMP-9) and Aquaporins-4 (AQP-4) in the hippocampus tissue. Double immunofluorescence further verified the protein expression of different biomarkers was localized in the astrocytes of the hippocampus. Hypercapnia alone did not disrupt the BBB, but it could further enhance the BBB permeability in hypoxemia. Concomitantly, up-regulation of nuclear HIF-1α, AQP-4, MMP-9 protein expression along with increased degradation of the occludin and claudin-5 proteins was found in the hypercapnia rat model, while the total HIF-1α remained unchanged. Interestingly, these changes were independent of the acidosis induced by hypercapnia. Of note, after premedication of 2-Methoxyestradiol (2ME2, an inhibitor of HIF-1α nuclear translocation), the disrupted BBB could be restored resulting in improvement of the cognitive impairment. Meanwhile, accumulation of nuclear HIF-1α, protein expression of AQP-4 and MMP-9 and protein degradation of the occludin and claudin-5 were decreased. Thus, our study demonstrated that hypercapnia can further disrupt the BBB through promoting HIF-1α nuclear translocation and up-regulation of AQP-4 and MMP-9 in hypoxemia. It is therefore suggested that the cascade of hypercapnia-induced nuclear HIF-1α protein translocation in hypoxia-activated astrocytes may be a potential target for ameliorating cognitive impairment.
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http://dx.doi.org/10.1007/s11064-020-03038-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7224048PMC
July 2020

Treatment with 7% and 10% CO enhanced expression of IL-1β, TNF-α, and IL-6 in hypoxic cultures of human whole blood.

J Int Med Res 2020 Apr;48(4):300060520912105

Department of Emergency and Critical Care Medicine, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China.

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http://dx.doi.org/10.1177/0300060520912105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7144675PMC
April 2020

GlnR Dominates Rifamycin Biosynthesis by Activating the Cluster Genes Transcription Both Directly and Indirectly in .

Front Microbiol 2020 3;11:319. Epub 2020 Mar 3.

College of Life Sciences, Shanghai Normal University, Shanghai, China.

Because of the remarkable efficacy in treating infections, rifamycin and its derivatives are still first-line antimycobacterial drugs. It has been intensely studied to increase rifamycin yield from , and nitrate is found to provide a stable and remarkable stimulating effect on the rifamycin production, a phenomenon known as "nitrate-stimulating effect (NSE)". Although the NSE has been widely used for the industrial production of rifamycin, its detailed molecular mechanism remains ill-defined. And our previous study has established that the global nitrogen regulator GlnR may participate in the NSE, but the underlying mechanism is still enigmatic. Here, we demonstrate that GlnR directly controls rifamycin biosynthesis in and thus plays an essential role in the NSE. Firstly, GlnR specifically binds to the upstream region of , which leads us to uncover that has its own promoter. As RifZ is a pathway-specific activator for the whole cluster, GlnR indirectly upregulates the whole cluster transcription by directly activating the expression. Secondly, GlnR specifically binds to the upstream region of , which is also characterized to have its own promoter. It is well-known that RifK is a 3-amino-5-hydroxybenzoic acid (AHBA, the starter unit of rifamycin) synthase, thus GlnR can promote the supply of the rifamycin precursor by directly activating the transcription. Notably, GlnR and RifZ independently activate the transcription through binding to different sites in promoter region, which suggests that the cells have a sophisticated regulatory mechanism to control the AHBA biosynthesis. Collectively, this study reveals that GlnR activates the cluster transcription in both direct (for and ) and indirect (for the whole cluster) manners, which well interprets the phenomenon that the NSE doesn't occur in the null mutant. Furthermore, this study deepens our understanding about the molecular mechanism of the NSE.
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http://dx.doi.org/10.3389/fmicb.2020.00319DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7062684PMC
March 2020

Single-cell transcriptomics reveals the alteration of peripheral blood mononuclear cells driven by sepsis.

Ann Transl Med 2020 Feb;8(4):125

Department of Emergency and Critical Care Medicine, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, China.

Background: Sepsis is a serious systemic inflammatory response syndrome caused by infection, with an extremely high mortality rate. Peripheral blood mononuclear cells (PBMCs) played a key role in the immune response against infection, whose components and functions were altered radically in Sepsis. Here, we wondered to characterize the alteration of PBMCs in sepsis at the single-cell transcriptional level.

Methods: We isolated PBMCs from seven septic patients and four donors. Based on BD Rhapsody, PBMCs were generated by single-cell RNA sequencing, and cell types were clustered and named by unsupervised clustering and annotation analysis.

Results: PBMCs were profiled for 6 kinds of cell types, the biological properties of T cell and monocytes were shown in a detailed manner. We noticed that monocytes could be clustered into 6 subsets, with great heterogeneity in the alteration of composition, gene profile, and signaling pathways driven by sepsis. Moreover, the expression of representative genes was high associated with septic clinical indicators in clusters of monocytes, such as NEAT1.

Conclusions: Although the study was preliminary, we revealed sepsis-specific alteration of PBMCs and associated pathways. These results give a panoramic picture of PBMCs in composition, genes profiles, and pathway signatures that are driven by sepsis, which offers a unique perspective to understand disease progression or treatment in clinical practice.
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http://dx.doi.org/10.21037/atm.2020.02.35DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7049046PMC
February 2020

NLRP3 inflammasome mediates M1 macrophage polarization and IL-1β production in inflammatory root resorption.

J Clin Periodontol 2020 04 7;47(4):451-460. Epub 2020 Feb 7.

Department of Orthodontics, The Affiliated Hospital of Qingdao University, Qingdao, China.

Aims: To explore the involvement of NOD-like receptor protein 3 (NLRP3) inflammasome and M1 macrophage in root resorption (RR).

Methods: A rat RR model was established by excessive orthodontic force. After different force-loading time, the expression levels of NLRP3, caspase-1, and interleukin-1β (IL-1β) and distribution of M1 macrophages were analysed by immunohistochemistry and immunofluorescence staining in vivo. Then, the mechanism of NLRP3 activation was further verified by macrophage and human periodontal ligament cell (hPDLC) co-culture system in vitro. The production levels of NLRP3, caspase-1, pro-caspase-1, and IL-1β in M1 macrophages in the co-culture system were detected by Western blot, and the polarization of CD68+IL-1β+ M1 macrophages was detected by immunofluorescence staining.

Results: In the rat RR model, NLRP3, caspase-1, IL-1β, and M1 macrophages were expressed in periodontal ligament, mainly concentrated around RR areas. Force-pre-treated hPDLCs promoted M1 macrophage polarization and the production of NLRP3, caspase-1, and IL-1β in M1 macrophages in co-culture system. When MCC950, an inhibitor of NLRP3 inflammasome, was added, NLRP3 activation and M1 macrophage polarization were inhibited.

Conclusions: In periodontal tissues, hPDLCs stimulated by force promoted M1 macrophage polarization and increased IL-1β production by activating NLRP3 inflammasome in M1 macrophages, thus initiating the occurrence of RR.
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http://dx.doi.org/10.1111/jcpe.13258DOI Listing
April 2020

The Subtilisin-Like Protease Bcser2 Affects the Sclerotial Formation, Conidiation and Virulence of .

Int J Mol Sci 2020 Jan 17;21(2). Epub 2020 Jan 17.

State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China.

, a ubiquitous necrotrophic plant-pathogenic fungus, is responsible for grey mold and rot disease in a very wide range of plant species. Subtilisin-like proteases (or subtilases) are a very diverse family of serine proteases present in many organisms and are reported to have a broad spectrum of biological functions. Here, we identified two genes encoding subtilisin-like proteases ( and ) in the genome of both of which contain an inhibitor I9 domain and a peptidase S8 domain. The expression levels of and increased during the sclerotial forming stage, as well as during a later stage of hyphal infection on leaves, but the up-regulation of was significantly higher than that of . Interestingly, deletion of had no effect on the fungal development or virulence of However, deletion of or double deletion of and severely impaired the hyphal growth, sclerotial formation and conidiation of . We also found that and / could not form complete infection cushions and then lost the ability to infect intact plant leaves of and tomato but could infect wounded plant tissues. Taken together, our results indicate that the subtilisin-like protease is crucial for the sclerotial formation, conidiation, and virulence of .
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http://dx.doi.org/10.3390/ijms21020603DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7013506PMC
January 2020

Multiple Effects of Mechanical Stretch on Myogenic Progenitor Cells.

Stem Cells Dev 2020 03 19;29(6):336-352. Epub 2020 Feb 19.

Department of Stomatology Medical Center, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao, China.

Mechanically stretched skeletal muscle undergoes dramatic shifts in structure, mass, and function. In vitro tensile strain models have demonstrated that myogenic progenitor cells, including satellite cells and myoblasts, are highly mechanosensitive cells, and respond to mechanical strain in a wide variety of aspects. However, the experimental results from different researchers and laboratories are not always in support of each other. Moreover, some specific molecules or signaling pathways were reported to play distinct roles in stretched myogenic cells, according to the statements of different studies. The purpose of this review is to integrate the researches conducting in vitro culture of satellite cells or myoblasts and exploring their mechanoresponses using in vitro stretching apparatus. These responses will be categorized into several groups, such as activation, proliferation, myogenic differentiation, cellular damage or apoptosis, properties of plasma membrane, transdifferentiation, reorientation, etc. In addition, detailed experimental designs like culturing conditions and straining regimens will be displayed and compared, to interpret some contradictory statements in different studies. Furthermore, the currently known interconnections among some mechanosensitive pathways will be pictured to give a better understanding about the complex regulations of myogenic cell responses to mechanical stretch. Hopefully, by summarizing the published studies about mechanoresponses of myogenic progenitor cells, future directions, and perspectives would be made clearer to researchers in this field.
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http://dx.doi.org/10.1089/scd.2019.0286DOI Listing
March 2020

Peri-operative risk factors for in-hospital mortality in acute type A aortic dissection.

J Thorac Dis 2019 Sep;11(9):3887-3895

Department of Intensive Care Unit 1, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, China.

Background: Acute type A aortic dissection (TAAD) is cardiovascular emergency and requires surgical interventions. In-hospital mortality rate of surgical-treated TAAD patients remains high. We aim to examine the prognostic implications of peri-operative parameters to identify high-risk patient for in-hospital mortality.

Methods: A total of 264 surgically treated TAAD patients were included in this study. The association between in-hospital mortality and peri-operative parameters were examined.

Results: Thirty patients (11.36%) died during hospitalization. Patients with higher Apache II score had a significantly higher rate of in-hospital mortality when compared with patients scored ≤20 in unadjusted model [Score 21-25: HR =12.9 (1.7-100.8), P=0.0148; Score >25: HR =94.5 (12.6-707.6), P<0.0001]. Patients with Sbp >120 mmHg, Cr >200 mmol/L (both at admission and after surgery), BUN >8.2 mmol/L (both at admission and after surgery), AST >80 µ/L, aortic cross-clamping time >120 min and cardiopulmonary bypass time (CPBT) >230 min were also significantly related to higher rate of in-hospital mortality in univariate analysis. In multivariable analysis, APACHE II score [Score 21-25: HR =9.5 (1.2-74.4), P=0.032; Score >25: HR =51.0 (6.7-387.7), P=0.0001], AST >80 µmol/L [HR =2.3 (1.1-4.8), P=0.0251], aortic cross-clamping time >120 min (HR =2.9 (1.1-7.7), P=0.0315) remained significant in predicting TAAD in-hospital mortality.

Conclusions: APACHE II score could be a useful tool to predict TAAD in-hospital mortality. AST >80 µ/L and aortic cross-clamping time >120 min were also independent predictors.
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http://dx.doi.org/10.21037/jtd.2019.09.11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6790434PMC
September 2019

Dental Follicle Stem Cells: Tissue Engineering and Immunomodulation.

Stem Cells Dev 2019 08 7;28(15):986-994. Epub 2019 May 7.

1Department of Orthodontics, the Affiliated Hospital of Qingdao University; School of Stomatology, Qingdao University, Qingdao, China.

Dental follicle stem cells (DFSCs), which are the stem cells present in the dental follicle tissue of the tooth germ and are derived from the neural crest, are direct precursor cells of periodontal tissues and can form the periodontal ligament, cementum, and alveolar bone proper in the late stage of tooth development. DFSCs have the ability to achieve osteogenic, adipogenic, chondrogenic, neural, and cardiomyocytic differentiation in a specific induced environment. Recently, isolated dental follicle epithelial stem cells from DFSCs were also found to have the ability to form salivary gland cells and ductal cells. In recent years, DFSCs have also been reported to play an active role in the treatment of inflammatory diseases and autoimmune diseases in animal models. Therefore, DFSCs could not only be used as a good seed source for tissue regeneration but also provide new treatment strategies for autoimmune diseases. The study of DFSCs in tissue regeneration and immunoregulation has developed from in vitro experiments to animal experiments. In this review, we will discuss recent advances in our understanding of DFSCs in tissue regeneration and immunomodulation. We expect DFSCs to be considered for stem cell-based therapies in the future.
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http://dx.doi.org/10.1089/scd.2019.0012DOI Listing
August 2019

[β1 receptor blocker decreases the myocardial inflammation in the sepsis adult rats through inhibition of TLR4/NF-ΚB signaling pathway].

Zhonghua Wei Zhong Bing Ji Jiu Yi Xue 2019 Feb;31(2):193-197

Department of Emergency and Critical Care Medicine, Guangdong Provincial People's Hospital and Guangdong Academy of Medical Sciences, Guangzhou 510080, Guangdong, China.

Objective: To explore whether β1 receptor blocker could decrease the myocardial inflammation through the Toll-like receptor 4/nuclear factor-ΚB (TLR4/NF-ΚB) signaling pathway in the sepsis adult rats.

Methods: Sixty male Wistar rats (250-300 g) aged 3 months old were allocated to four groups by random number table (n = 15): sham operation group (S group), sepsis model group (CLP group), β1 receptor blocker esmolol intervention group (ES group), and inhibitor of the TLR4 E5564 intervention group (E5564 group). The rat sepsis model was established by cecal ligation and puncture (CLP); S group of rats underwent only an incision. Rats in S group, CLP group and E5564 group were subcutaneous injected with 0.9% sodium chloride (NaCl) 2.0 mL/kg. Besides, the rats in ES group were injected with esmolol (15 mg×kg×h) by micro pump through the caudal vein. The rats in E5564 group were injected with E5564 (0.3 mg×kg×h) by micro pump through the caudal vein 1 hour before the CLP surgery. Samples were collected 6 hours after the modelling in each group. The average arterial pressure (MAP) and cardiac output index (CI) were monitored by PU electrical conduction ECG monitor. The levels of serum cardiac troponin I (cTnI), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were detected by enzyme linked immunosorbent assay (ELISA). The expressions of TLR4, NF-ΚB p65, IL-1β, TNF-α in myocardial tissue was detected by Western Blot.

Results: There was no significant difference in MAP in each group. Compared with the S group, the CI in the CLP group was significantly decreased, the levels of serum cTnI, IL-1β, TNF-α were significantly increased, the protein expressions of myocardial tissue TLR4, NF-ΚB p65, IL-1β and TNF-α were significantly increased. Compared with the CLP group, the CI in the ES group and E5564 group were significantly increased (mL×s×m: 58.6±4.3, 58.9±4.4 vs. 41.2±3.9, both P < 0.01), the levels of serum cTnI, IL-1β and TNF-α were significantly decreased [cTnI (μg/L): 1 113.81±26.64, 1 115.74±25.90 vs. 1 975.96±42.74; IL-1β (ng/L): 39.6±4.3, 38.9±4.4 vs. 61.2±3.9; TNF-α (ng/L): 43.1±2.8, 48.7±2.6 vs. 81.3±4.4, all P < 0.01], the protein expressions of myocardial tissue NF-ΚB p65, IL-1β, TNF-α were significantly decreased (NF-ΚB p65/β-actin: 0.31±0.03, 0.43±0.04 vs. 0.85±0.08; IL-1β/β-actin: 0.28±0.05, 0.32±0.03 vs. 0.71±0.06; TNF-α/β-actin: 0.18±0.04, 0.28±0.03 vs. 0.78±0.07, all P < 0.01), but there was no significant difference in protein expression of TLR4 (TLR4/β-actin: 0.89±0.07, 0.87±0.09 vs. 0.95±0.09, both P > 0.05). There was no significant difference in CI, the levels of serum cTnI, IL-1β, TNF-α, and the protein expressions of myocardial tissue TLR4, NF-ΚB p65, IL-1β, TNF-α between ES group and E5564 group (all P > 0.05).

Conclusions: β1 receptor blocker esmolol may inhibit myocardial inflammatory response in sepsis adult rats through TLR4/NF-ΚB signaling pathway, thereby alleviating sepsis-induced myocardial injury.
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http://dx.doi.org/10.3760/cma.j.issn.2095-4352.2019.02.014DOI Listing
February 2019

Insight into the Molecular Mechanism of the Transcriptional Regulation of Operon in .

Front Microbiol 2018 20;9:264. Epub 2018 Feb 20.

CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.

In , transcription is promptly regulated by the global nitrogen regulator GlnR. Although the GlnR binding -element has been characterized in promoter, consisting of three GlnR boxes of , , and , its role in GlnR-mediated transcriptional regulation remains unclear. Here, we showed that GlnR had different binding affinity against each pair of GlnR binding sites in promoter (i.e., , , and sites), and GlnR was able to bind and , respectively, but not alone. Consistently, was not a typical GlnR binding site and further experiments showed that was non-essential for GlnR-mediated binding and transcriptional regulation . To uncover the physiological role of the three GlnR boxes, we then mutated the wild-type promoter to a typical GlnR-binding motif containing two GlnR boxes (), and found although the transcription of the mutated promoter could still be activated by GlnR, its increasing rate was less than that of the wild-type. Based on these findings, one could conclude that the three GlnR boxes assisted GlnR in more promptly activating transcription in response to nitrogen limitation, facilitating bacterial growth under nitrogen stresses.
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http://dx.doi.org/10.3389/fmicb.2018.00264DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5826061PMC
February 2018

A feedback regulatory model for RifQ-mediated repression of rifamycin export in Amycolatopsis mediterranei.

Microb Cell Fact 2018 Jan 29;17(1):14. Epub 2018 Jan 29.

CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 500 Caobao Road, Shanghai, 200233, China.

Background: Due to the important role of rifamycin in curing tuberculosis infection, the study on rifamycin has never been stopped. Although RifZ, which locates within the rifamycin biosynthetic cluster, has recently been characterized as a pathway-specific regulator for rifamycin biosynthesis, little is known about the regulation of rifamycin export.

Results: In this work, we proved that the expression of the rifamycin efflux pump (RifP) was regulated by RifQ, a TetR-family transcriptional regulator. Deletion of rifQ had little impact on bacterial growth, but resulted in improved rifamycin production, which was consistent with the reverse transcription PCR results that RifQ negatively regulated rifP's transcription. With electrophoretic mobility shift assay and DNase I Footprinting assay, RifQ was found to directly bind to the promoter region of rifP, and a typical inverted repeat was identified within the RifQ-protected sequences. The transcription initiation site of rifP was further characterized and found to be upstream of the RifQ binding sites, well explaining the RifQ-mediated repression of rifP's transcription in vivo. Moreover, rifamycin B (the end product of rifamycin biosynthesis) remarkably decreased the DNA binding affinity of RifQ, which led to derepression of rifamycin export, reducing the intracellular concentration of rifamycin B as well as its toxicity against the host.

Conclusions: Here, we proved that the export of rifamycin B was repressed by RifQ in Amycolatopsis mediterranei, and the RifQ-mediated repression could be specifically relieved by rifamycin B, the end product of rifamycin biosynthesis, based on which a feedback model was proposed for regulation of rifamycin export. With the findings here, one could improve the antibiotic yield by simply inactivating the negative regulator of the antibiotic transporter.
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http://dx.doi.org/10.1186/s12934-018-0863-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5787919PMC
January 2018

RifZ (AMED_0655) Is a Pathway-Specific Regulator for Rifamycin Biosynthesis in Amycolatopsis mediterranei.

Appl Environ Microbiol 2017 04 31;83(8). Epub 2017 Mar 31.

State Key Laboratory of Genetic Engineering, Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai, China

Rifamycin and its derivatives are particularly effective against the pathogenic mycobacteria and Although the biosynthetic pathway of rifamycin has been extensively studied in , little is known about the regulation in rifamycin biosynthesis. Here, an transposon system was employed to identify genes involved in the regulation of rifamycin production in U32. In total, nine rifamycin-deficient mutants were isolated, among which three mutants had the transposon inserted in (, encoding a LuxR family regulator). The gene was further knocked out via homologous recombination, and the transcription of genes in the rifamycin biosynthetic gene cluster ( cluster) was remarkably reduced in the null mutant. Based on the cotranscription assay results, genes within the cluster were grouped into 10 operons, sharing six promoter regions. By use of electrophoretic mobility shift assay and DNase I footprinting assay, RifZ was proved to specially bind to all six promoter regions, which was consistent with the fact that RifZ regulated the transcription of the whole cluster. The binding consensus sequence was further characterized through alignment using the RifZ-protected DNA sequences. By use of bionformatic analysis, another five promoters containing the RifZ box (CTACC-N8-GGATG) were identified, among which the binding of RifZ to the promoter regions of both and () was further verified. As RifZ directly regulates the transcription of all operons within the cluster, we propose that RifZ is a pathway-specific regulator for the cluster. To this day, rifamycin and its derivatives are still the first-line antituberculosis drugs. The biosynthesis of rifamycin has been extensively studied, and most biosynthetic processes have been characterized. However, little is known about the regulation of the transcription of the rifamycin biosynthetic gene cluster ( cluster), and no regulator has been characterized. Through the employment of transposon screening, we here characterized a LuxR family regulator, RifZ, as a direct transcriptional activator for the cluster. As RifZ directly regulates the transcription of the entire cluster, it is considered a pathway-specific regulator for rifamycin biosynthesis. Therefore, as the first regulator characterized for direct regulation of cluster transcription, RifZ may provide a new clue for further engineering of high-yield industrial strains.
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http://dx.doi.org/10.1128/AEM.03201-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5377510PMC
April 2017

Histone H3 Lysine 9 Methyltransferase DIM5 Is Required for the Development and Virulence of Botrytis cinerea.

Front Microbiol 2016 22;7:1289. Epub 2016 Aug 22.

State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China; Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural UniversityWuhan, China.

Histone methylation is widely present in animals, plants and fungi, and the methylation modification of histone H3 has important biological functions. Methylation of Lys9 of histone H3 (H3K9) has been proven to regulate chromatin structure, gene silencing, transcriptional activation, plant metabolism, and other processes. In this work, we investigated the functions of a H3K9 methyltransferase gene BcDIM5 in Botrytis cinerea, which contains a PreSET domain, a SET domain and a PostSET domain. Characterization of BcDIM5 knockout transformants showed that the hyphal growth rate and production of conidiophores and sclerotia were significantly reduced, while complementary transformation of BcDIM5 could restore the phenotypes to the levels of wild type. Pathogenicity assays revealed that BcDIM5 was essential for full virulence of B. cinerea. BcDIM5 knockout transformants exhibited decreased virulence, down-regulated expression of some pathogenic genes and drastically decreased H3K9 trimethylation level. However, knockout transformants of other two genes heterochromatin protein 1 (HP1) BcHP1 and DNA methyltransferase (DIM2) BcDIM2 did not exhibit significant change in the growth phenotype and virulence compared with the wild type. Our results indicate that H3K9 methyltransferase BcDIM5 is required for H3K9 trimethylation to regulate the development and virulence of B. cinerea.
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http://dx.doi.org/10.3389/fmicb.2016.01289DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4992730PMC
September 2016

[Esmolol improves clinical outcome and tissue oxygen metabolism in patients with septic shock through controlling heart rate].

Zhonghua Wei Zhong Bing Ji Jiu Yi Xue 2015 Sep;27(9):759-63

Objective: To investigate whether esmolol could improve clinical outcome and tissue oxygen metabolism by controlling heart rate (HR) in patients with septic shock.

Methods: A single-center double-blinded randomized controlled trial was conducted. The patients suffering from septic shock received 6-hour early goal directed herapy (EGDT) with pulmonary artery wedge pressure ≥ 12 mmHg (1 mmHg = 0.133 kPa) or central venous pressure CVP) ≥ 12 mmHg requiring norepinephrine to maintain mean arterial pressure (MAP) ≥ 65 mmHg and HR ≥ 95 bpm admitted to intensive care unit (ICU) of Guangdong General Hospital from September 2013 to September 2014 were enrolled. They were randomly divided into esmolol group and control group by computer-based random number generator. All patients received conventional basic treatment, while those in the esmolol group received in addition persistent esmolol infusion by micro pump with dosage of 0.05 mg · kg(-1) · min(-1) with the dosage adjusted to maintain HR lower than 100 bpm within 24 hours. The patients in control group did not receive drug intervention for HR. The primary end-points consisted of length of stay in ICU and 28-day mortality. The secondary end-points included hemodynamic parameters [HR, MAP, CVP, cardiac index (CI), stroke volume index (SVI), systemic vascular resistance index (SVRI)] and tissue oxygen metabolism parameters [central venous oxygen saturation (ScvO2), lactate level (Lac)] before and 24, 48, 72 hours after the treatment.

Results: A total of 48 patients with septic shock were enrolled with 24 patients in esmolol group and 24 in control group. (1) The primary end-points: compared with control group, the length of stay in the ICU in the esmolol group was significantly shortened (days: 13.75 ± 8.68 vs. 21.70 ± 6.06, t = 3.680, P = 0.001), and 28-day mortality was significantly lowered [25.0% (6/24) vs. 62.5% (15/24 ), χ2 = 6.857, P = 0.009]. (2) The secondary end-points: there were no significant difference in the hemodynamic and tissue metabolism parameters before treatment between two groups. No significant difference was found between before and after treatment of all above parameters in control group. HR and Lac in the esmolol group were obviously declined, SVI, SVRI, SCvO2 were gradually increased, but no significant difference in MAP, CVP, and CI was found. Compared with the control group, HR in the esomolol group was significantly lowered (bpm: 84.4 ± 3.5 vs. 111.2 ± 7.2, P < 0.01), SVRI and ScvO2 were significantly increased from 24 hours [SVRI (kPa · s · L(-1) ·m(-2)): 137.9 ± 1.6 vs. 126.9 ± 1.3, ScvO2: 0.652 ± 0.017 vs. 0.620 ± 0.017, both P < 0.01]; SVI was significantly increased (mL/m2: 39.9 ± 2.2 vs. 36.8 ± 1.7, P < 0.01) and Lac level significantly declined from 48 hours (mmol/L: 2.8 ± 0.3 vs. 3.4 ± 0.3, P < 0.01).

Conclusion: The results demonstrate that HR controlled by a titrated esmolol infusion given to septic shock patients was associated with an improvement in tissue metabolism, reduction in the length of ICU stay and lowering of 28-day mortality.
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September 2015

High secretory production of an alkaliphilic actinomycete xylanase and functional roles of some important residues.

World J Microbiol Biotechnol 2014 Jul 11;30(7):2053-62. Epub 2014 Mar 11.

State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100, People's Republic of China.

Using native signal peptide, an alkaliphilic actinomycete xylanase XynK was overexpressed in Escherichia coli and secreted into the culture medium completely. At its optimum catalytic temperature of 55 °C, the cellulose-free xylanase exhibits high activity and stability at pH 7.0-11.0. In comparison with the well-studied actinomycete xylanase from Streptomyces lividans, as an alkaliphilic xylanase, XynK exhibited different biochemical and catalytic characteristics. With the aid of site-directed mutagenesis, some residues were demonstrated to be important to the activity, stability, or substrate binding of the enzyme. The pH stability of mutants H131S and W135A both decreased obviously under high pH values. Combined with their K(m) parameters and homology model analysis, His131 was proposed to be important to both substrate binding and enzyme catalyzing, whereas Trp135 significantly influenced enzyme stability. Good stability under alkaline condition, as well as high secretory expression implies good potentials of the alkaline xylanase in various industrial applications. In addition, results from site-directed mutagenesis provide useful information for further pH stability mechanisms investigation.
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http://dx.doi.org/10.1007/s11274-014-1630-3DOI Listing
July 2014

Close relationship of a novel Flavobacteriaceae α-amylase with archaeal α-amylases and good potentials for industrial applications.

Biotechnol Biofuels 2014 Jan 31;7(1):18. Epub 2014 Jan 31.

State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, People's Republic of China.

Background: Bioethanol production from various starchy materials has received much attention in recent years. α-Amylases are key enzymes in the bioconversion process of starchy biomass to biofuels, food or other products. The properties of thermostability, pH stability, and Ca-independency are important in the development of such fermentation process.

Results: A novel Flavobacteriaceae Sinomicrobium α-amylase (FSA) was identified and characterized from genomic analysis of a novel Flavobacteriaceae species. It is closely related with archaeal α-amylases in the GH13_7 subfamily, but is evolutionary distant with other bacterial α-amylases. Based on the conserved sequence alignment and homology modeling, with minor variation, the Zn2+- and Ca2+-binding sites of FSA were predicated to be the same as those of the archaeal thermophilic α-amylases. The recombinant α-amylase was highly expressed and biochemically characterized. It showed optimum activity at pH 6.0, high enzyme stability at pH 6.0 to 11.0, but weak thermostability. A disulfide bond was introduced by site-directed mutagenesis in domain C and resulted in the apparent improvement of the enzyme activity at high temperature and broad pH range. Moreover, about 50% of the enzyme activity was detected under 100°C condition, whereas no activity was observed for the wild type enzyme. Its thermostability was also enhanced to some extent, with the half-life time increasing from 25 to 55 minutes at 50°C. In addition, after the introduction of the disulfide bond, the protein became a Ca-independent enzyme.

Conclusions: The improved stability of FSA suggested that the domain C contributes to the overall stability of the enzyme under extreme conditions. In addition, successfully directed modification and special evolutionary status of FSA imply its directional reconstruction potentials for bioethanol production, as well as for other industrial applications.
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http://dx.doi.org/10.1186/1754-6834-7-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3922116PMC
January 2014

Characterization of a novel metagenome-derived 6-phospho-β-glucosidase from black liquor sediment.

Appl Environ Microbiol 2013 Apr 18;79(7):2121-7. Epub 2013 Jan 18.

State Key Laboratory of Microbial Technology, Shandong University, Jinan, People's Republic of China.

The enzyme 6-phospho-β-glucosidase is an important member of the glycoside hydrolase family 1 (GH1). However, its catalytic mechanisms, especially the key residues determining substrate specificity and affinity, are poorly understood. A metagenome-derived gene sequence, encoding a novel 6-phospho-β-glucosidase designated Pbgl25-217, was isolated and characterized. The optimal conditions for enzymatic activity were 37°C and pH 7; Ca(2+), Mg(2+), and Mn(2+) stabilized the activity of Pbgl25-217, whereas Ni(2+), Fe(2+), Zn(2+), Cu(2+), and Fe(3+) inhibited its activity. The Km and Vmax of Pbgl25-217 were 4.8 mM and 1,987.0 U mg(-1), respectively. Seven conserved residues were recognized by multiple alignments and were tested by site-directed mutagenesis for their functions in substrate recognition and catalytic reaction. The results suggest that residues S427, Lys435, and Tyr437 act as "gatekeepers" in a phosphate-binding loop and play important roles in phosphate recognition. This functional identification may provide insights into the specificity of 6-phospho-β-glycosidases in GH1 and be useful for designing further directed evolution.
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http://dx.doi.org/10.1128/AEM.03528-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3623223PMC
April 2013

Analysis of the effect of CPP-ACP tooth mousse on enamel remineralization by circularly polarized images.

Angle Orthod 2010 Sep;80(5):933-8

Department of Orthodontics, The Affiliated Hospital of Medical College, Qingdao University, Qingdao, China.

Objective: To evaluate the effect of casein phosphopeptide-amorphous calcium phosphate tooth mousse on the remineralization of bovine incisor by circularly polarized images.

Methods: Eighty bovine incisors, each with a 4 x 4 mm artificially demineralized area, were used. The samples were divided into four groups: Group A, casein phosphopeptide-amorphous calcium phosphate tooth mousse; Group B, fluoride toothpaste; Group C, casein phosphopeptide-amorphous calcium phosphate tooth mousse and fluoride toothpaste; and Group D, no treatment. Circularly polarized images were taken after the specimens were treated for 3, 6, 9, or 12 weeks, and the size of the demineralized area and the mean grey level were measured. Data analysis was done using repeated measures variance analysis. Pearson correlation coefficients were computed to evaluate the correlation between the size of the demineralized area and the mean grey level.

Results: In all four groups, the size of the demineralized area and the mean grey level declined with time. The size of the demineralized area of Group C was significantly smaller than that of Group A at the end of the third and sixth weeks (P = .039, P = .000, respectively), and the mean grey level of Group C was lower than that of Group A at the end of the 6th and 12th weeks (P = .037, P = .004, respectively). At the end of the 6th, 9th, and 12th weeks, the size of the demineralized area of Group C was smaller (P = .000, P = .005, P = .005, respectively) and the mean grey level was lower (P = .000) than those of Group B. No statistically significant correlations were detected between the size of the demineralized area and the mean grey level.

Conclusion: Casein phosphopeptide-amorphous calcium phosphate tooth mousse can reduce the size and mean grey level of demineralized areas and promote the remineralization of bovine enamel. Combined application with fluoride toothpaste strengthens the effect.
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http://dx.doi.org/10.2319/110509-624.1DOI Listing
September 2010

Adsorption of Rh(III) complexes from chloride solutions obtained by leaching chlorinated spent automotive catalysts on ion-exchange resin Diaion WA21J.

J Hazard Mater 2010 Jul 1;179(1-3):104-12. Epub 2010 Mar 1.

Key Laboratory of Ecological and Recycling Metallurgy, Ministry of Education of China, Beijing 100083, China.

It was found that Rh, Pd and Pt contained in the spent ceramic automotive catalysts could be effectively extracted by dry chlorination with chlorine. In order to concentrate Rh(III) ions contained in the chloride solutions obtained, thermodynamic and kinetics studies for adsorption of Rh(III) complexes from the chloride solutions on an anionic exchange resin Diaion WA21J were carried out. Rh, Pd, Pt, Al, Fe, Si, Zn and Pb from the chloride solution could be adsorbed on the resin. The distribution coefficients (K(d)) of Rh(III) decreased with the increase in initial Rh(III) concentration or in adsorption temperature. The isothermal adsorption of Rh(III) was found to fit Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich models under the adsorption conditions. The maximum monolayer adsorption capacities Q(max) based on Langmuir adsorption isotherms were 6.39, 6.61 and 5.81 mg/g for temperatures 18, 28 and 40 degrees C, respectively. The apparent adsorption energy of Rh was about -7.6 kJ/mol and thus Rh(III) adsorption was a physical type. The experimental data obtained could be better simulated by pseudo-first-order kinetic model and the activation energy obtained was 6.54 J/mol. The adsorption rate of Rh(III) was controlled by intraparticle diffusion in most of time of adsorption process.
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http://dx.doi.org/10.1016/j.jhazmat.2010.02.064DOI Listing
July 2010

Adsorption of Pd(II) complexes from chloride solutions obtained by leaching chlorinated spent automotive catalysts on ion exchange resin Diaion WA21J.

J Colloid Interface Sci 2010 May 25;345(1):12-8. Epub 2010 Jan 25.

Key Laboratory of Ecological and Recycling Metallurgy, Ministry of Education of China, Beijing 100083, China.

It was found that Rh, Pd and Pt contained in the spent ceramic automotive catalysts could be effectively extracted by dry chlorination with chlorine. In order to concentrate Pd(II) contained in the chloride solution obtained from the dry chlorination process, thermodynamic and kinetics studies for adsorption of Pd(II) complexes from the chloride solutions on anionic exchange resin Diaion WA21J were carried out. It was found that Pd, Pt, Rh, Al, Fe, Si, Zn and Pb from the chloride solution could be adsorbed on the resin. The isothermal adsorption of Pd(II) was found to fit Freundlich, Langmuir and Dubinin-Kaganer-Radushkevich models under the adsorption conditions. The adsorption of Pd(II) on the resin was favorable according to the values of 1/n and R(L) from Freundlich and Langmuir adsorption isotherms, respectively. The maximum monolayer adsorption capacities Q(max) based on Langmuir adsorption isotherms were 5.70, 4.84 and 4.05 mg/g and the corresponding value X(m) based on Dubinin-Kaganer-Radushkevich were 5.55, 4.69 and 4.01 mg/g at temperatures 18 degrees C, 28 degrees C and 40 degrees C, respectively. The apparent adsorption energies (E(ad)) based on Dubinin-Kaganer-Radushkevich isotherm were -15.43, -16.22 and -23.57 kJ/mol for the temperatures 18 degrees C, 28 degrees C and 40 degrees C, respectively. Chemical adsorption was a main mechanism involved in the adsorption process. Pd(II) adsorption on the resin could be accelerated by increasing the adsorption temperature. The adsorption of Pd(II) from the chloride solution on the resin underwent pseudo-first order kinetic process and the apparent adsorption activation energy E(a) was 15.0 kJ/mol. The intra-particle diffusion was a main rate controlling step in the Pd(II) adsorption process under the adsorption conditions.
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http://dx.doi.org/10.1016/j.jcis.2010.01.049DOI Listing
May 2010