C-TYPE LECTIN-2D RECEPTOR CONTRIBUTES TO HISTONE-INDUCED VASCULAR BARRIER DYSFUNCTION DURING BURN INJURY

ABSTRACT

Severe burns are associated with massive tissue destruction and cell death where nucleus histones and other damage-associated molecular patterns are released into the circulation and contribute to the pathogenesis of multiple-organ dysfunction. Currently, there is limited information regarding the pathophysiology of extracellular histones after burns, and the mechanisms underlying histone-induced vascular injury are not fully understood. In this study, by comparing the blood samples from healthy donors and burn patients, we confirmed that burn injury promoted the release of extracellular histones into the circulation, evidenced by increased plasma levels of histones correlating with injury severity. The direct effects of extracellular histones on human endothelial monolayers were examined, and the results showed that histones caused cell-cell adherens junction discontinuity and barrier dysfunction in a dose-related manner. Like burn patients, mice subjected to a scald burn covering 25% total body surface area also displayed significantly increased plasma histones. Intravital microscopic analysis of mouse mesenteric microcirculation indicated that treatment with a histone antibody greatly attenuated burn-induced plasma leakage in postcapillary venules, supporting the pathogenic role of extracellular histones in the development of microvascular barrier dysfunction during burns. At the molecular level, intrigued by the recent discovery of C-type lectin domain family 2 member D (Clec2d) as a novel receptor of histones, we tested its potential involvement in the histone interaction with endothelial cells. Indeed, we identified abundant expression of Clec2d in vascular endothelial cells. Further proximity ligation assay demonstrated a close association between extracellular histones and endothelial expressing Clec2d. Functionally, in vivo administration of an anti-Clec2d antibody attenuated burn-induced plasma leakage across mesenteric microvessels. Consistently, Clec2d knockdown in endothelial cells partially inhibited histone-induced endothelial barrier dysfunction. Together, our data suggest that burn injury-induced increases in circulating histones contribute to microvascular leakage and endothelial barrier dysfunction via a mechanism involving the endothelial Clec2d receptor.

Photolysis frequency of nitrophenols derived from ambient measurements

Nitrophenols, a class of important intermediate products from the oxidation of aromatics, can participate in photochemistry and influence the atmospheric oxidative capacity. However, the reported photolysis frequencies of nitrophenols show considerable discrepancies. Here, measurements of nitrophenol, and methyl nitrophenol using a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) at both urban and regional sites in southern China are used to constrain photolysis frequencies of nitrophenols. Considerable concentrations with a campaign average of 58 ± 32 ppt for nitrophenol and 97 ± 59 ppt for methyl nitrophenol were observed at the regional site. Based on the in-situ measurement dataset, a steady-state calculation was performed along with a zero-dimensional box model to analyze the budgets of nitrophenols. The result indicates that both primary emission and photolysis have significant impacts on nitrophenols. Primary emission contributes up to 88 % of the total nitrophenols production while photolysis accounts for up to 98 % of the total removal rate. The dominant sink of nitrophenols is photolysis with a rate of about 3.5 % ± 1.3 % of j_NO2 for nitrophenol and 2.4 % ± 1.0 % of j_NO2 for methyl nitrophenol. The results of this study suggest that using advanced mass spectrometry to accurately measure ambient nitrophenols, supplemented by an observation-based box model for budget analysis, provides an important indication for determining photolysis rate constants of nitrophenols.

Protein palmitoylation regulates extracellular vesicle production and function in sepsis

Extracellular vesicles (EVs) are bioactive membrane-encapsulated particles generated by a series of events involving membrane budding, fission and fusion. Palmitoylation, mediated by DHHC palmitoyl acyltransferases, is a lipidation reaction that increases protein lipophilicity and membrane localization. Here, we report palmitoylation as a novel regulator of EV formation and function during sepsis. Our results showed significantly decreased circulating EVs in mice with DHHC21 functional deficiency (Zdhhc21dep/dep), compared to wild-type (WT) mice 24 h after septic injury. Furthermore, WT and Zdhhc21dep/dep EVs displayed distinct palmitoyl-proteomic profiles. Ingenuity pathway analysis indicated that sepsis altered several inflammation related pathways expressed in EVs, among which the most significantly activated was the complement pathway; however, this sepsis-induced complement enrichment in EVs was greatly blunted in Zdhhc21dep/dep EVs. Functionally, EVs isolated from WT mice with sepsis promoted neutrophil adhesion, transmigration, and neutrophil extracellular trap production; these effects were significantly attenuated by DHHC21 loss-of-function. Furthermore, Zdhhc21dep/dep mice displayed reduced neutrophil infiltration in lungs and improved survival after CLP challenges. These findings indicate that blocking palmitoylation via DHHC21 functional deficiency can reduce sepsis-stimulated production of complement-enriched EVs and attenuates their effects on neutrophil activity.

Burn Injury-Induced Extracellular Vesicle Production and Characteristics

ABSTRACT

Extracellular vesicles (EVs) are nano-sized membrane-bound particles containing biologically active cargo molecules. The production and molecular composition of EVs reflect the physiological state of parent cells, and once released into the circulation, they exert pleiotropic functions via transferring cargo contents. Thus, circulating EVs not only serve as biomarkers, but also mediators in disease processes or injury responses. In the present study, we performed a comprehensive analysis of plasma EVs from burn patients and healthy subjects, characterizing their size distribution, concentration, temporal changes, cell origins, and cargo protein contents. Our results indicated that burn injury induced a significant increase in circulating EVs, the response peaked at the time of admission and declined over the course of recovery. Importantly, EV production correlated with injury severity, as indicated by the total body surface area and depth of burn, requirement for critical care/ICU stay, hospitalization length, wound infection, and concurrence of sepsis. Burn patients with inhalation injury showed a higher level of EVs than those without inhalation injury. We also evaluated patient demographics (age and sex) and pre-existing conditions (hypertension, obesity, and smoking) and found no significant correlation between these conditions and overall EV production. At the molecular level, flow cytometric analysis showed that the burn-induced EVs were largely derived from leukocytes and endothelial cells (ECs), which are known to be activated postburn. Additionally, a high level of zona-occludens-1 (ZO-1), a major constituent of tight junctions, was identified in burn EV cargos, indicative of injury in tissues that form barriers via tight junctions. Moreover, when applied to endothelial cell monolayers, burn EVs caused significant barrier dysfunction, characterized by decreased transcellular barrier resistance and disrupted cell-cell junction continuity. Taken together, these data suggest that burn injury promotes the production of EVs containing unique cargo proteins in a time-dependent manner; the response correlates with injury severity and worsened clinical outcomes. Functionally, burn EVs serve as a potent mediator capable of reducing endothelial barrier resistance and impairing junction integrity, a pathophysiological process underlying burn-associated tissue dysfunction. Thus, further in-depth characterization of circulating EVs will contribute to the development of new prognostic tools or therapeutic targets for advanced burn care.

Validation of a modified Caprini risk assessment model in lung cancer patients undergoing surgery: Results of a multicenter cross-sectional observational study

BACKGROUND AND OBJECTIVES

Lung cancer patients slated for surgery are at high risk of venous thromboembolism (VTE). Precise risk assessment is necessary for providing proper thromboprophylaxis and reducing morbidity and mortality of VTE.

METHODS

A multicenter, observational, cross-sectional cohort study, involving patients with primary lung cancer undergoing surgery, was carried out from August 2016 to December 2019. All patients were assessed according to the Caprini risk assessment model (RAM) and a modified scoring system incorporating elevated D-dimer and new stratification of surgical time. The endpoint was confirmed VTE or patient discharge.

RESULTS

Out of 1205 patients, 87 (7.2%) were diagnosed with VTE. The area under the curve of modified scores for VTE was 0.759, which was larger than that of the original one (0.589) (p < 0.05). By modified Caprini scoring system, a higher score was associated with increased VTE risk (odds ratio [OR], 1.345; 95% confidence interval [CI], 1.197-1.512; p < 0.001), and there was an increased OR of 4.090 (95% CI, 2.472-6.768, p < 0.001) for VTE in high-risk category patients.

CONCLUSION

Modified Caprini RAM showed an improved prediction of high-risk patients with an elevated likelihood of postoperative VTE compared to the original one.

A large-scale genome-wide association analysis reveals QTL and candidate genes for intramuscular fat content in Duroc pigs

This study aimed at identifying genomic regions and genes associated with intramuscular fat content (IMF) in Duroc pigs using a weighted single-step GWAS. Data from 3912 pigs, of which 3770 animals were genotyped with GeneSeek Porcine 50K Bead chip, were used for the association analysis. We identified 19 genomic regions that each explained >1% of the additive genetic variance associated with IMF. Notably, a consistent QTL on SSC7 (117.42-117.92 Mb) was confirmed, explaining 3.70% of the additive genetic variance, and two genes, BDKRB2 and ATG2B, were highlighted as promising candidates for IMF. Two QTL (SSC7, 94.19-94.64 Mb; SSC14, 123.25-123.75 Mb), which harbored MED6 and MAP3K9 genes and TCF7L2 gene respectively, were newly identified as associated with IMF. In conclusion, we identified a consistent QTL and additional genomic regions and genes that contributed to the genetic variance of IMF using a large-scale sample size of genotyped pigs and genealogical information.

DHHC21 deficiency attenuates renal dysfunction during septic injury

Renal dysfunction is one of the most common complications of septic injury. One critical contributor to septic injury-induced renal dysfunction is renal vascular dysfunction. Protein palmitoylation serves as a novel regulator of vascular function. Here, we examined whether palmitoyl acyltransferase (PAT)-DHHC21 contributes to septic injury-induced renal dysfunction through regulating renal hemodynamics. Multispectral optoacoustic imaging showed that cecal ligation and puncture (CLP)-induced septic injury caused impaired renal excretion, which was improved in DHHC21 functional deficient (Zdhhc21^dep/dep) mice. DHHC21 deficiency attenuated CLP-induced renal pathology, characterized by tissue structural damage and circulating injury markers. Importantly, DHHC21 loss-of-function led to better-preserved renal perfusion and oxygen saturation after CLP. The CLP-caused reduction in renal blood flow was also ameliorated in Zdhhc21^dep/dep mice. Next, CLP promoted the palmitoylation of vascular α1-adrenergic receptor (α1AR) and the activation of its downstream effector ERK, which were blunted in Zdhhc21^dep/dep mice. Vasoreactivity analysis revealed that renal arteries from Zdhhc21^dep/dep mice displayed reduced constriction response to α1AR agonist phenylephrine compared to those from wild-type mice. Consistently, inhibiting PATs with 2-bromopalmitate caused a blunted vasoconstriction response to phenylephrine in small arteries isolated from human kidneys. Therefore, DHHC21 contributes to impaired renal perfusion and function during septic injury via promoting α1AR palmitoylation-associated vasoconstriction.

A97 TOOLS FOR DIRECT OBSERVATION AND ASSESSMENT OF COLONOSCOPY: A SYSTEMATIC REVIEW OF VALIDITY EVIDENCE

Background

An increasing focus on quality and safety in colonoscopy has led to broader implementation of competency-based educational systems that enable documentation of trainees’ achievement of the knowledge, skills, and attitudes needed for independent practice. The meaningful assessment of competence in colonoscopy is critical to this process. While there are many published tools that assess competence in performing colonoscopy, there is a wide range of underlying validity evidence. Tools with strong evidence of validity are required to support feedback provision, optimize learner capabilities, and document competence.

Aims

We aimed to evaluate the strength of validity evidence that supports available colonoscopy direct observation assessment tools using the unified framework of validity.

Methods

We systematically searched five databases for studies investigating colonoscopy direct observation assessment tools from inception until April 8, 2020. We extracted data outlining validity evidence from the five sources (content, response process, internal structure, relations to other variables, and consequences) and graded the degree of evidence, with a maximum score of 15. We assessed educational utility using an Accreditation Council for Graduate Medical Education framework and methodological quality using the Medical Education Research Quality Instrument (MERSQI).

Results

From 10,841 records, we identified 27 studies representing 13 assessment tools (10 adult, 2 pediatric, 1 both). All tools assessed technical skills, while 10 assessed cognitive and integrative skills. Validity evidence scores ranged from 1–15. The Assessment of Competency in Endoscopy (ACE) tool, the Direct Observation of Procedural Skills (DOPS) tool, and the Gastrointestinal Endoscopy Competency Assessment Tool (GiECAT) had the strongest validity evidence, with scores of 13, 15, and 14, respectively. Most tools were easy to use and interpret and required minimal resources. MERSQI scores ranged from 9.5–11.5 (maximum score 14.5).

Conclusions

The ACE, DOPS, and GiECAT have strong validity evidence compared to other assessments. Future studies should identify barriers to widespread implementation and report on use of these tools in credentialing purposes.

Funding Agencies

None

Protein Palmitoylation in Leukocyte Signaling and Function

Palmitoylation is a post-translational modification (PTM) based on thioester-linkage between palmitic acid and the cysteine residue of a protein. This covalent attachment of palmitate is reversibly and dynamically regulated by two opposing sets of enzymes: palmitoyl acyltransferases containing a zinc finger aspartate-histidine-histidine-cysteine motif (PAT-DHHCs) and thioesterases. The reversible nature of palmitoylation enables fine-tuned regulation of protein conformation, stability, and ability to interact with other proteins. More importantly, the proper function of many surface receptors and signaling proteins requires palmitoylation-meditated partitioning into lipid rafts. A growing number of leukocyte proteins have been reported to undergo palmitoylation, including cytokine/chemokine receptors, adhesion molecules, pattern recognition receptors, scavenger receptors, T cell co-receptors, transmembrane adaptor proteins, and signaling effectors including the Src family of protein kinases. This review provides the latest findings of palmitoylated proteins in leukocytes and focuses on the functional impact of palmitoylation in leukocyte function related to adhesion, transmigration, chemotaxis, phagocytosis, pathogen recognition, signaling activation, cytotoxicity, and cytokine production.

Management strategies in a thoracic surgery ward during COVID-19 pandemic: Experience from West China Hospital

The coronavirus disease 2019 was first reported in Wuhan in December 2019 and then spread rapidly throughout the world. On March 11, 2020, the World Health Organization declared coronavirus disease 2019 a pandemic. In response to the pandemic, the management division of West China Hospital oversaw the implementation of hospital-wide emergency measures. In accordance with these measures, the hospital's thoracic surgery ward implemented a new management system by reformulating staff training plans, patient admission procedures, and other systems for managing the ward and protecting perioperative patients. Overall, the ward was successful in restoring normal working order, protecting all staff from occupational exposures, and ensuring the safety of inpatients and their families.

[Current Status of Prevention and Nursing on Venous Thromboembolism among Perioperative Patients with Lung Cancer]

BACKGROUND

The purpose of this study was to explore the status of prevention and nursing on venous thromboembolism (VTE) among perioperative patients with lung cancer in Chinese hospital.

METHODS

A self-designed questionnaire was used to investigate 108 head nurses from tertiary hospitals during the first West China Forum on Chest Enhanced Recovery After Surgery (ERAS).

RESULTS

(1) Current status of assessment tools and prevention guidelines: 97.22% of the hospitals have carried out VTE risk assessments for surgical patients with lung cancer, 67.59% of the hospitals have established the nursing prevention specifications of VTE. (2) Current status of screening, precaution and follow-up: 56.48% of the hospitals have taken different approach to screen VTE for lung cancer patients in pre-operative period. 90.74% of the hospitals and 52.78% of the hospitals had VTE prophylaxis for hospitalized and discharged patients, but only 17.59% of hospitals were followed up on the incidence of VTE for discharged patients. (3) There was no statistically significant difference in VTE prevention between different type hospitals (P>0.05). But, all patients in the specialist hospital have been fully implemented on VTE risk assessment and VTE prevention (100.00%).

CONCLUSIONS

The clinical staff have already realized the importance of VTE prevention, and the VTE prevention in perioperative patients with lung cancer has received extensive attention. But there is still lack of effective risk assessment tools and standardized guidelines of VTE prevention.

Esophagogastric junction outflow obstruction is often associated with coexistent abnormal esophageal body motility and abnormal bolus transit

Currently, the diagnosis of esophageal motility disorders is in part based upon a hierarchical algorithm in which abnormalities of the esophagogastric junction (EGJ) is prioritized. An important metric in evaluating the EGJ is the integrated relaxation pressure (IRP). Patients who do not have achalasia but are found to have an elevated IRP are diagnosed with EGJ outflow obstruction. It has been our observation that a subset of these patients also has a second named motility disorder and may also have abnormal bolus transit. The aim of this study is to determine the frequency of abnormal body motility and or abnormal bolus movement in patients with EGJ outflow obstruction. Further, in an effort to evaluate the potential clinical value in measuring bolus transit as a complement to esophageal manometry, specifically in patients with EGJ outflow obstruction, we analyzed the presenting symptoms of these patients. A total of 807 patients with a mean age of 53 years completed esophageal function testing with impedance monitoring and high-resolution manometry between January 2012 and October 2016. There were 74 patients with achalasia who were excluded from the study. Of the remaining 733 patients, 138 (19%) had an elevated IRP and were given a diagnosis of EGJ outflow obstruction. Among these patients, 56 (40%) were diagnosed with an abnormal motility pattern to liquids (ineffective esophageal motility = 28, distal esophageal spasm = 19, Jackhammer = 6), of which 44 (76%) had abnormal bolus transit to liquids, viscous, or both. In contrast, there were 82 patients with EGJ outflow obstruction and normal esophageal motility, of which 33 (40%) had abnormal bolus transit. Patients with preserved esophageal motility and EGJ outflow obstruction were then evaluated. Of the 733 patients, 299 (40%) had intact esophageal motility. Of the 299 patients with normal esophageal motility, 56 patients had an elevated IRP, of which 16 (28%) had abnormal bolus transit. There were 243 (33%) patients with intact esophageal motility and normal IRP. Of these, 56 (23%) patients had abnormal bolus transit. Among patients with abnormal bolus transit, the two most commonly presenting symptoms were dysphagia and heartburn. A substantial percentage of patients with EGJ outflow obstruction have abnormal esophageal body motility and or abnormal bolus transit. The clinical implications of EGJ outflow obstruction need to be further elucidated as current criteria do not allow for the description of other abnormalities in esophageal motility and bolus transit among patients who are given the diagnosis of EGJ outflow obstruction.

[Determination of trace Pb and Cd in water treatment reagent by graphite furnace atomic absorption spectrometry]

The optimum conditions for the determination of trace Pb and Cd in water treatment reagent by graphite furnace atomic absorption spectrometry were studied in detail in this paper. The results show that the long and tedious pretreatment process was cut down by calibrating background with D2 lamp and NH4H2PO4 as matrix modifier. The determination limits were 0.65 microgram.L-1 and 0.12 microgram.L-1 for (Pb and Cd) and linear ranges were 0-50 micrograms.L-1, 0-20 micrograms.L-1 for Pb and Cd, respectively. Rate of recovery was 90%-110%. This method is accurate, quick and simple, and can be used successfully to determine actual samples.

[Intrahepatic portal vein compliance in cirrhosis]

OBJECTIVE

To elaborate the effects of increase in portal flow on intrahepatic vein compliance with isolated perfused cirrhotic model (IPCM).

METHOD

Cirrhosis was induced by CCl(4) in 80 Wistar rats, which were divided into two groups A and B, by portal with/without hepato-artery. Portal flow was increased and hemodynamic parameters were recorded and analysed.

RESULT

In group A, compared with 1.65 +/- 0.28 kPa at basal control, portal pressure was elevated from 2.55 +/- 0.40 kPa to 3.96 +/- 0.67 kPa. Q(35)-Q(55) flow rates were raised from 35 to 55 ml/min, respectively. A correlation existed between portal flows and pressures (r = 0.985, P < 0.01). The low flow rate of 15 ml/min at Q(15) caused a irreversible model injury. A largest flow rate in IPCM was, less than in IPRL. In group B, no low flow-injury was found.

CONCLUSION

Portal vein compliance of liver is decreased markedly in cirrhotic portal hypertension, but hepatic flow is increased. There are likely some compensative relations between portal and hepato-arterial system.

[Studies of loss of heterozygosity(LOH) in Chinese human gastric cancer tissues]

OBJECTIVE

To identify the LOH frequency in Chinese gastric cancer samples and locate lost region of gastric cancer-related tumor suppressor gene.

METHODS

Thirty microsatellite markers were used to examine 42 cases of tumor-normal paired gastric cancer tissues for LOH on all chromosomes (except Y) using polymerase chain reaction(PCR).

RESULTS

The total frequency of LOH in 42 gastric cancer was 27.7%. High frequencies of LOH (> or = 40%) were observed at loci D3S1067, D3S1577, D6S430, D15S205, D17S945, and D5S407, D2S136, D2S147, D13S175, D14S68, D8S279 loci had LOH frequency > or = 30%. Significantly more LOH cases were observed in the poorly differentiated type and the signet-cell type than in well differentiated type of gastric cancers (P = 0.00699 and 0.0001). The incidence of LOH in signet-cell cancer was even significantly higher than that in poorly differentiated gastric carcinomas(P = 0.0019). LOH was not found in 4 cases with well differentiated gastric cancer.

CONCLUSION

The most common LOH occurred at D3S1577, D3S1067, D5S407, D6S430, D8S279, D15S205 and D17S945 might imply the existence of potential tumor suppressor genes of gastric cancer.

An EPROM-based heart-rate meter with wide range and multifunctions

A digital heart-rate meter has been developed to display instantaneous as well as average heart-rate of 4 or 8 beats. The display resolution is 1 beat min-1 (BPM) in the range of 13-362 BPM, and 8 BPM in the range of up to 999 BPM. The whole circuit consists of 10 general-purpose integrated circuits (including LCDs). Two EPROM 2716 chips are preprogrammed with heart-rate data. A 12-bit binary counter, which sums the clock pulses between beat-to-beat intervals, is used to address the EPROMs to send appropriate data to the LCD display. We conclude that, with the resolution of 1 BPM, the relationship between the counting clock frequency f and upper display limit f' and lower display limit f" are: f' approximately square root 60f; f" = 60f/Nmax Where Nmax is the capacity of the EPROMs. To extend the dislay range, two clock frequencies, i.e. 256 Hz and 2048 Hz, are generated and switched automatically according to the heart-rate measured. The former is for the heart-rate less than 120 BPM, and the latter is for that higher than 120BPM.

[Effect of Na2SeO3 on the damages of genetic materials induced by MNNG in children's foreskin fibroblasts in vitro]

In order to study the effect of selenium on anticarcinogenesis, micronuclei (MN) and chromosome aberrations (CA) were used as the indexes to reflect the damages on the genetic materials induced by MNNG in children's foreskin fibroblasts in vitro. In the MN test, the final concentrations of Na2SeO3 were 10(-7), 10(-6), 10(-5) and 10(-4) M and MNNG, 10(-5)M. In the CA test, Na2SeO3 were used in 10(-7), 10(-6) and 10(-5)M and MNNG, 10(-6)M as the final concentrations. Relative to the time of MNNG treatment, the cells were exposed to Na2SeO3 4 hours before and at the same time as with the carcinogen. The results showed that the MN% (number of cells out of one thousand MN) was reduced from 4.31 +/- 0.91% to 1.55 +/- 0.54% and 1.54 +/- 0.54% (P less than 0.05), respectively. The CA% (the percentage of the cell with CA) was reduced from 86 +/- 7% to 34 +/- 9% and 33 +/- 9% (P less than 0.05), respectively. However there was no like results when the cells were treated with Na2SeO3 and MNNG simultaneously. Na2SeO3 had no significant protective effects on the cells when the concentration was 10(-7)M. If the dose was 10(-4)M or more, Na2SeO3 became toxic to the cells. The results suggested that the protection of Na2SeO3 on the damages of genetic materials induced by MNNG be time and dose dependent.