Azalomycin F4a targets peptidoglycan synthesis of Gram-positive bacteria revealed by high-throughput CRISPRi-seq analysis.

Azalomycin F4a is a promising 36-membered polyhydroxy macrolide that shows antibacterial activity against drug-resistant Gram-positive bacteria, but its exact working mechanism remains to be elusive. Here, we isolated the azalomycin F4a product from a Streptomyces solisilvae and demonstrated its antibacterial activity against Gram-positive pathogens including Streptococcus pneumoniae, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA). We further showed that combination of azalomycin F4a with methicillin has an additive antimicrobial effect on MRSA, where the minimal inhibitory concentrations (MIC) of methicillin to MRSA was decreased by 1000-fold in the presence of sublethal concentration of azalomycin F4a. A CRISPRi-seq based whole genome screen was employed to identify the potential targets of azalomycin F4a, which revealed that peptidoglycan synthesis (PGS) was inhibited by azalomycin F4a. Furthermore, azalomycin F4a treatment could significantly impair S. aureus biofilm formation. Our research highlights that cell wall synthesis is an additional target for novel classes of macrolide besides ribosome.

A Bacterial Quorum Sensing Regulated Protease Inhibits Host Immune Responses by Cleaving Death Domains of Innate Immune Adaptors.

Innate immune adaptor proteins are critical components of the innate immune system that propagate pro-inflammatory responses from their upstream receptors, and lead to pathogen clearance from the host. Bacterial pathogens have developed strategies to survive inside host cells without triggering the innate immune surveillance in ways that are still not fully understood. Here, it is reported that Pseudomonas aeruginosa induces its quorum sensing mechanism after macrophage engulfment. Further investigation of its secretome identified a quorum sensing regulated product, LasB, is responsible for innate immune suppression depending on the MyD88-mediated signaling. Moreover, it is showed that this specific type of pathogen-mediated innate immune suppression is due to the enzymatic digestion of the death domains of the innate immune adaptors, mainly MyD88, and attributed to LasB's large substrate binding groove. Lastly, it is demonstrated that the secretion of LasB from P. aeruginosa directly contributed to MyD88 degradation within macrophages. Hence, it is discovered an example of bacterial quorum sensing-regulated cellular innate immune suppression by direct cleavage of immune adaptors.

The role of closed-loop management of fever patients in a county-level medical community for the prevention and control of the post-coronavirus disease 2019 pandemic.

We built a closed-loop management model for patients with fever in a county-level medical community and explored the role of this model in post-coronavirus disease 2019 (COVID-19) epidemic prevention and control. The subjects included 83,791 patients with fever treated in designated hospitals between February 2020 and April 2021. A pre-hospital, in-hospital, and post-hospital management system for patients with fever in the county-level medical community was established to allow the closed-loop management of these patients. SPSS software (version 13.0) was used to analyze the methods of visiting the hospital, nucleic acid detection in the hospital, and location of the patients after the hospital visit. Chi-square tests were used to compare the methods of visiting and location after hospital visits between patients with and without an epidemiological history. The number of patients with fever in the fever clinic showed a logarithm change (R2 = 0.4710), accompanied by seasonal changes. The number of fever patients with an epidemiological history decreased logarithmically monthly (R2 = 0.8876). Among patients with fever, 99.64% sought medical treatment on their own, with relatively low proportions undergoing home quarantine and requiring centralized quarantine special vehicles. After visiting the fever clinics, 98.56% of patients isolated at home or were monitored, with small proportions of patients requiring hospital admission or centralized isolation. However, the proportions of patients with home and centralized isolation with epidemiology were relatively high, accounting for 20.55% and 27.40% of cases, respectively. Compared to the overall population of patients with fever, the difference was statistically significant (χ2 = 48.881, P = .000). The establishment of a closed-loop management model for patients with fever in a county-level medical community strengthened the management of these patients. No local cases occurred in Beilun District between March 2020 and April 2021. In the post-COVID-19 era, all medical institutions in the county-level medical community strengthened infectious disease pre-examination and triage and promoted the formation of a strategic pattern of initial diagnosis at the grassroots level, 2-way referral, upper and lower linkage, and joint epidemic prevention. This management was more conducive to COVID prevention and control by hierarchical management according to the presence or absence of an epidemiological history.

Effects of preconditioning by nasal splint and mouth breathing on emergence delirium after functional endoscopic sinus surgery in Chinese adults: a study protocol for a randomised controlled trial.

INTRODUCTION: Emergence delirium (ED) is a common adverse manifestation after general anaesthesia and may result in undesirable consequences. Its causes and mechanisms are diverse and complex, and it is still unavoidable in clinical work. There is a high incidence of ED after otorhinolaryngology surgery, which may result from the sudden loss of functional senses and discomfort of surgical organs. This study aims to test a non-invasive, non-drug treatment modality of nose clamping and mouth-breathing training before surgery to reduce ED. METHODS AND ANALYSIS: This prospective randomised controlled trial (RCT) will include 200 patients who undergo functional endoscopic sinus surgery (FESS) at Shanghai General Hospital, China. Study participants will be randomly assigned in two groups with a 1:1 ratio. The pretreatment group (P-group) will receive an intervention by nasal splint and mouth-breathing training before surgery, while the control group (C-group) will not receive any intervention; following which both groups will undergo FESS under general anaesthesia in accordance with the same anaesthesia scheme. After surgery, we will perform a single-blinded assessment of ED occurrence with stratification. IBM SPSS Statistics V.20 statistical software will be used for statistical analyses. A X2 test will be used to compare the two groups, and t-tests will determine the statistical significance of continuous variables. ETHICS AND DISSEMINATION: This RCT was designed in accordance with the principles of the Declaration of Helsinki and has been approved by the Ethics Committee of Shanghai General Hospital, ID: 2019KY039.We expect to release the original data in February 2022 on the ResMan original data sharing platform (IPD sharing platform) of the China clinical trial registry, which can be viewed at the following website:http://www.medresman.org.cn/pub/cn/proj/projectshow.aspx?proj=6293. TRIAL REGISTRATION NUMBER: ChiCTR1900024925.

Regionally infused lidocaine can dose-dependently protect the ischemic spinal cord in rabbits and may be associated with the EAA changes.

OBJECTIVE: In our previous study, we found that lidocaine, infused through the abdominal aorta, could protect the spinal cord against the ischemia-reperfusion (I/R) injury caused by aortic occlusion. However, whether lidocaine protective effects have dose-dependent properties and its underlying mechanisms still remain unclear. This study was designed to investigate whether regionally infused lidocaine could dose-dependently protect spinal cord against I/R injury in rabbits and its underlying mechanism. METHODS: 46 New Zealand white rabbits were randomized into six groups: Group NS (normal saline control); Group L10 (lidocaine 10 mg/kg); Group L20 (lidocaine 20 mg/kg); Group L40 (lidocaine 40 mg/kg); Group L80 (lidocaine 80 mg/kg) and Group Sham. In Group NS, Group L10, Group L20, Group L40 and Group L80, spinal cord ischemia was induced by infrarenal aortic occlusion for 30 min. The sham group did not receive spinal cord ischemia. During the occlusion, normal saline or lidocaine at different doses was infused continuously through a catheter into the clamped abdominal aorta respectively. Neurologic behavior functions were assessed according to the Tarlov scale system at the moments of 0, 6, 24 and 48 h after reperfusion. The neural injuries were evaluated by the histological examination and the count of normal α-motor neurons in the ventral horn. The levels of excitatory amino acids (EAAs) in the spinal cord, including glutamate (Glu) and aspartic acid (Asp), were analyzed by high performance liquid chromatography with fluorescence detection. RESULTS: The Tarlov scales in the Group L20 and the Group L40 were significantly higher than those in the Group NS at 24 and 48 h after reperfusion (P < 0.05). 12.5 % animals in Group L40 and 25 % animals in Group L20 were paraplegic versus 75 % animals in Group NS at 48 h after reperfusion (P < 0.05). The median of normal α-motor neurons in the L20, L40 and L80 groups was 7.5, 9 and 5 respectively which was significantly higher than in the NS group (count 0, P < 0.05). The levels of L-ASP and L-Glu remarkably decreased in the Group L10 and the Group L40 compared to Group NS (P < 0.05). CONCLUSIONS: These data revealed that regional administration of lidocaine through the abdominal aorta can provide dose-dependent protection on spinal cord I/R in rabbits. Inhibition of EAA release may be one of the underlying mechanisms.

A novel protease inhibitor causes inclusion vacuole reduction and disrupts the intracellular growth of Chlamydia trachomatis.

Chlamydia (C.) trachomatis, characterized by a unique biphasic life cycle, is an obligate intracellular bacterial pathogen which is responsible for the highest number of sexually transmitted bacterial infections globally. However, its pathogenic mechanisms have not been fully elucidated because of its unique developmental cycle and obligate intracellular nature. High temperature requirement (HtrA), a critical protease and chaperone, has been previously demonstrated to be essential for several functions and the replicative phase in the C. trachomatis developmental cycle. In the current study, we designed and synthesized a novel peptidomimetic inhibitor targeting C. trachomatis HtrA (CtHtrA) using homology modeling and chemical synthesis. The inhibitor was tested in chlamydia in the mid-replicative phase and resulted in a significant loss of viable infectious progeny and diminishing inclusion size and number at a relatively low concentration. This finding not only indicates that CtHtrA plays a critical role during the replicative phase of the chlamydial developmental cycle but also reveals a useful target for the design of novel anti-chlamydial agents.

Antiangiogenic effects of AA-PMe on HUVECs in vitro and zebrafish in vivo.

Angiogenesis plays a vital role in many physiological and pathological processes and several diseases are connected with its dysregulation. Asiatic acid (AA) has demonstrated anticancer properties and we suspect this might be attributable to an effect on angio-genesis. A modified derivative of AA, N-(2α,3ß,23-acetoxyurs-12-en-28-oyl)-L-proline methyl ester (AA-PMe), has improved efficacy over its parent compound, but its effect on blood vessel development remains unclear. METHODS: In this study, we investigated the antiangiogenic activity of AA and AA-PMe in zebrafish embryos and human umbilical vein endothelial cells (HUVECs). First of all, we treated HUVECs with increasing concentrations of AA-PMe or AA, with or without vascular endothelial growth factor (VEGF) present, and assessed cell viability, tube formation, and cell migration and invasion. Quantitative real-time polymerase chain reaction and Western blot analysis were later used to determine the role of vascular endothelial growth factor receptor 2 (VEGFR2)-mediated signaling in AA-PMe inhibition of angiogenesis. We extended these studies to follow angiogenesis using Tg(fli:EGFP) transgenic zebrafish embryos. For these experiments, embryos were treated with varying concentrations of AA-PMe or AA from 24 to 72 hours postfertilization prior to morphological observation, angiogenesis assessment, and endogenous alkaline phosphatase assay. VEGFR2 expression in whole embryos following AA-PMe treatment was also determined. RESULTS: We found AA-PMe decreased cell viability and inhibited migration and tube formation in a dose-dependent manner in HUVECs. Similarly, AA-PMe disrupted the formation of intersegmental vessels, the dorsal aorta, and the posterior cardinal vein in zebrafish embryos. Both in vitro and in vivo AA-PMe surpassed AA in its ability to block angiogenesis by suppressing VEGF-induced phosphorylation of VEGFR2 and disrupting downstream extracellular regulated protein kinase and AKT signaling. CONCLUSION: For the first time, this study reveals that AA-PMe acts as a potent VEGFR2 kinase inhibitor and exerts powerful antiangiogenic activity, suggesting it to be a promising therapeutic candidate for further research.

Heterochronic truncation of odontogenesis in theropod dinosaurs provides insight into the macroevolution of avian beaks.

Beaks are innovative structures characterizing numerous tetrapod lineages, including birds, but little is known about how developmental processes influenced the macroevolution of these important structures. Here we provide evidence of ontogenetic vestigialization of alveoli in two lineages of theropod dinosaurs and show that these are transitional phenotypes in the evolution of beaks. One of the smallest known caenagnathid oviraptorosaurs and a small specimen of the Early Cretaceous bird Sapeornis both possess shallow, empty vestiges of dentary alveoli. In both individuals, the system of vestiges connects via foramina with a dorsally closed canal homologous to alveoli. Similar morphologies are present in Limusaurus, a beaked theropod that becomes edentulous during ontogeny; and an analysis of neontological and paleontological evidence shows that ontogenetic reduction of the dentition is a relatively common phenomenon in vertebrate evolution. Based on these lines of evidence, we propose that progressively earlier postnatal and embryonic truncation of odontogenesis corresponds with expansion of rostral keratin associated with the caruncle, and these progenesis and peramorphosis heterochronies combine to drive the evolution of edentulous beaks in nonavian theropods and birds. Following initial apomorphic expansion of rostral keratinized epithelia in perinatal toothed theropods, beaks appear to inhibit odontogenesis as they grow postnatally, resulting in a sequence of common morphologies. This sequence is shifted earlier in development through phylogeny until dentition is absent at hatching, and odontogenesis is inhibited by beak formation in ovo.

General Anesthetics Regulate Autophagy via Modulating the Inositol 1,4,5-Trisphosphate Receptor: Implications for Dual Effects of Cytoprotection and Cytotoxicity.

General anesthetics are both neuroprotective and neurotoxic with unclear mechanisms. General anesthetics may control cell survival via their effects on autophagy by activation of type 1 inositol triphosphate receptor (InsP3R-1). DT40 or SH-SY5Y cells with only or over 99% expression of InsP3R-1 were treated with isoflurane or propofol. Cell viability was determined by MTT reduction or LDH release assays. Apoptosis was determined by measuring Caspase-3 or by TUNEL assay. Autophagy activity was determined by measuring LC3 II and P62. We evaluated mitochondrial integrity using MitoTracker Green and cytosolic ATP levels. Fura2-AM was used to measure the concentrations of cytosolic calcium ([Ca2+]c). Propofol significantly increased peak and integrated calcium response (P < 0.001) in cells with InsP3R-1 but not in cells with triple knockout of InsP3R. Both propofol and isoflurane increased autophagy induction (P < 0.05) in an mTOR- and InsP3R- activity dependent manner. Short exposure to propofol adequately activated InsP3-1 to provide sufficient autophagy for cytoprotection, while prolonged exposure to propofol induced cell apoptosis via impairment of autophagy flux through over activation of InsP3-1. Propofol damaged mitochondria and decreased cytosolic ATP. The effects of general anesthetics on apoptosis and autophagy are closely integrated; both are caused by differential activation of the type 1 InsP3R.

Denervation stage differentially influences resistance to neuromuscular blockers in rat gastrocnemius.

BACKGROUND: Muscle denervation was common in clinical surgery patients, which was mostly caused by trauma, paraplegia, and other factors. Denervated muscle in patients could lead to significant differential reaction to neuromuscle blockers due to the time of denervation and affected muscle area. We tested the hypothesis that resistance to non-depolarizing muscle relaxants (NDMRs) changes with time, and is related to the expression of immature and total acetylcholine receptors (AChRs). MATERIALS AND METHODS: The study evaluated the effect change of neuromuscular blockers in tibial nerve transected rat model. To determine 50% effective dose of NDMRs and succinycholine at 1, 7, 14, 28, and 35 days after denervation, action potential amplitude was monitorted by intracellular recording method. The messenger DNA that encodes the AChR-γ and AChR-ε subunits and the protein of the -γ and -ε subunits were quantified in the gastrocnemius by reverse transcription-polymerase chain reaction and western blotting respectively. Receptor number and pharmacodynamic changes was analyzed by correlation and regression analysis. RESULTS: Increased AChR-γ correlated with total AChRs, suggesting that the up-regulated AChRs may contain the immature isoform. The 50% effective dose of vecuronium and atracurium increased 1.2- to 1.5-fold at all time periods and correlated significantly with AChRs and AChR-γ. CONCLUSIONS: After denervation, resistance to NDMRs occurred earlier, was more marked from 14 days, and changes in resistance to NDMRs in skeletal muscle after nerve injury is dependent on the level of expression of immature and total AChRs. Denervation time should be of concern when such patients undergo surgery.

Cerebral protective effect of nicorandil premedication on patients undergoing liver transplantation.

BACKGROUND: Neurological injury is a common complication in the early period after liver transplantation, posing an enormous obstacle to treatment efficiency and patient survival. Nicorandil is a mitochondrial ATP-sensitive potassium channel (mitoKATP) opener. It has been reported to be effective in reducing brain injury in recent studies. However, it is still unclear whether nicorandil has cerebral protective effect in patients undergoing liver transplantation. METHODS: Fifty patients scheduled for liver transplantation were randomly divided into a nicorandil group (group N) (n=25), in which patients received 10 mg nicorandil through a nasogastric tube 30 minutes before induction of anesthesia, and a control group (group C) (n=25) who received 10 mL normal saline. The Mini-Mental State Examination (MMSE) was performed before anesthesia (day 0), and on days 3 and 7 after surgery. Blood samples were obtained before induction of anesthesia (T1), and at 12 (T2) and 36 hours (T3) after surgery for determination of serum neuron-specific enolase (NSE) and S100ß protein (S100ß) concentrations. RESULTS: During surgery, 5 patients in each group were eliminated due to severe reperfusion or renal insufficiency. Therefore, 20 patients remained in each group. The MMSE scores after operation were significantly lower than those before operation in group C. However, there was no difference at days 3 and 7 compared with day 0 in group N. Serum NSE concentrations after surgery were significantly higher than baseline (at T1) in both groups, except at T3 in group N. Serum S100ß concentration after surgery was significantly higher than baseline (at T1) in both groups. The MMSE scores at days 3 and 7 in group N were significantly higher than those in group C. The concentrations of serum NSE and S100ß at T2 and T3 in group N were significantly lower than those in group C. CONCLUSIONS: Oral nicorandil, as a premedication before liver transplantation, improves postoperative MMSE scores. It also attenuates the increase of NSE and S100ß in blood, indicating its cerebral protective effect.

A single small dose of ketamine prevents lung injury following hepatic ischemia-reperfusion in rabbits.

BACKGROUND: Previous studies demonstrated that large-dose ketamine alleviated lipopolysaccharide-induced lung injury. We investigated whether a single small dose of ketamine could attenuate lung injury induced by hepatic ischemia-reperfusion (HIR) and, if so its underlying mechanisms. METHODS: Thirty male New Zealand rabbits were randomized into three groups (n = 10 each): sham group (Group S), control group (Group C), and ketamine group (Group K). In Group S, hepatic portal vein (HPV) and inferior vena cava (IVC) were left unclamped and 0.9% saline 1 mL/kg was given intravenously. In Group K, ketamine 0.5 mg/kg (0.5 mg/mL) was given intravenously 10 minutes before cross-clamping of the HPV and the IVC. In Group C, 0.9% saline was given 10 minutes before the cross-clamping. The HPV and the IVC were cross-clamped with bulldog clamps and unclamped 60 minutes later in the Group K and the Group C. Blood pressure and pulse rate were recorded throughout the procedure. Rabbits were sacrificed 6 hours postoperatively. Lung W/D ratio was calculated and expression of tumor necrosis factor-α mRNA, intracellular adhesion molecule-1 mRNA, and nuclear factor kappa B (NF-κB)/p65 were quantitatively analyzed. Accumulation of neutrophils in lung tissues was also observed. RESULTS: Small dose of ketamine alleviated the pulmonary edema, but not the systemic hypotension, induced by cross-clamping of the IVC and the HPV. Pretreatment with ketamine significantly reduced the increments of tumor necrosis factor-α mRNA, intracellular adhesion molecule-1 mRNA, and NF-κB/p65; and inhibited the aggregation of neutrophils in lung tissues following HIR. CONCLUSION: 0.5 mg/kg ketamine pretreatment showed significant protective effect on acute lung injury induced by HIR, which might be mediated by the NF-κB pathway.