A40 GUT MICROBIOTA PROMOTES NUTRIENT AVAILABLITY AND PATHOGENESIS OF AN ATTACHING/ EFFACING BACTERIAL PATHOGEN

Background

Our gut microbiota plays an important role in protecting the gastrointestinal (GI) tract from invading enteric pathogens. Much of this colonization resistance is mediated by limiting nutrient availability, however, enteric pathogens have evolved strategies to subvert this competition, utilizing commensal metabolites to facilitate their infection. Access to nutrients is not only crucial for a pathogen’s metabolic fitness, but can also drive the expression of virulence factors, a process high in energy demands. In addition, enteric pathogens, such as the attaching and effacing (A/E) bacterium Citrobacter rodentium, must cross the colonic mucus layer that normally prevents their direct access to the underlying epithelium. Intestinal mucus is comprised of highly glycosylated mucins, with the sugar sialic acid frequently occupying the terminal position of their O-glycan side chains. We hypothesize that C. rodentium utilizes commensal-liberated mucin sugars, such as sialic acid, as nutrients and signals to promote its virulence.

Purpose

This study investigates the mechanisms by which A/E pathogens reach the colonic mucosal surface, and the role played by commensal microbes in facilitating the infection.

Method

Expression of virulence factors secreted by C. rodentium in the presence or absence of sialic acid was analyzed by SDS-PAGE and mass spectrometry. Next, we infected specific-pathogen free (SPF), germfree (GF), and previously GF C57Bl/6 mice mono-colonized with Bacteroides thetaotaomicron, a mucus-degrading commensal, to examine their susceptibility to C. rodentium and to measure the levels of free sialic acid in their feces.

Result(s)

Sensing of sialic acid by C. rodentium, was found to induce the secretion of several key virulence proteins, enhancing the pathogen’s migration across the colonic mucus layer and adhesion to the underlying epithelium. Access to sialic acid within the gut environment was enhanced in the presence of microbiota, as the levels of free sialic acid were low in GF mice. Interestingly, despite GF mice carrying very high C. rodentium burdens, passage across the mucus layer and infection of their colonic epithelium was impaired as compared to SPF mice. Notably, B. thetaotaomicron was found to degrade whole mucus in vitro, facilitating its consumption by C. rodentium for growth, while B. thetaotaomicron mono-colonized GF mice showed increased susceptibility to colonic infection by C. rodentium.

Conclusion(s)

We demonstrate that although commensal microbes promote colonization resistance, as an A/E pathogen infection establishes, specific commensal bacteria accelerate infection in the GI tract by releasing an important nutrient, ie. sialic acid, from mucus. Access to sialic acid promotes C. rodentium virulence by inducing the key virulence factors that facilitate its translocation across the mucus layer as well as adhesion to the epithelium, thereby expediting disease progression.

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CCC, CIHR, Other

Please indicate your source of funding;

CH.I.L.D. Foundation

Disclosure of Interest

None Declared

A15 GENETIC OR DIET-ASSOCIATED DEFECTS IN MUCUS FACILITATE ULCERATIVE COLITIS PATHOBIONT-DRIVEN COLITIS

Background

The Inflammatory Bowel Diseases (IBD), Crohn’s Disease (CD) and ulcerative colitis (UC) affect > 270,000 Canadians and are increasing in incidence. Ileal CD has been linked to the overgrowth of mucosal adherent E. coli. Recent studies have also implicated the adherence of Escherichia coli pathobionts to the colonic mucosa of UC patients. Using the representative UC E. coli pathobiont p19A, we recently demonstrated it aggravated chemical-induced colitis in susceptible mice, through the actions of the toxin alpha-hemolysin, and by adhering to the inflamed colonic mucosa via the adhesin FimH. It is less clear what host factors control susceptibility to the UC pathobionts. One of the potential candidates is the glycosylated mucin (Muc2) which forms the mucus layer that covers the colonic epithelium and is often impaired in UC patients.

Purpose

To define the role of mucus structure and function in determining susceptibility to the p19A pathobiont, and its ability to cause colitis in mice.

Method

In vitro growth was assessed to test p19A’s ability to utilize mucin-derived sugars as nutrients. Susceptibility to p19A was tested in two mouse models of colonic mucus impairment. The first is a mouse strain deficient in core 1 derived O-glycans in their intestinal epithelial cells (IEC C1galt1^-/-), resulting in reduced Muc2 glycosylation, and thus a thin and impaired mucus barrier. The second model involves feeding wildtype (WT) C57BL/6CR mice a fiber-free (FF) diet, resulting in a significantly thinner colonic mucus layer. The mice were subsequently orally gavaged with p19A and their susceptibility determined by p19A burdens, intestinal histopathology, inflammatory cytokine and short chain fatty acid (SCFA) production.

Result(s)

When tested in vitro, the p19A pathobiont was found to use an array of mucin-derived sugars as sole carbon source to proliferate. Following oral gavage of WT mice fed a normal diet, immunostaining identified p19A within the colonic mucus but it did not reach the colonic mucosa or cause disease. In contrast, p19A was found at the colonic mucosal surface of mucus-defective IEC C1galt1^-/- mice (as compared to IEC C1galt1^flox/flox mice) and in WT mice fed a fiber-free diet. This mucosal adherence was associated with increased body weight loss during the course of infection, as well as increased p19A burdens, colonic pathology and pro-inflammatory cytokine expression. Especially fiber-free diet-fed mice showed reduced SCFA levels in their feces at baseline. When the mice were given exogenous SCFA (tributyrin) orally, p19A infection was reduced.

Conclusion(s)

Our results indicate that UC E. coli pathobionts are able to dwell within colonic mucus and utilize mucin sugars as nutrients. Moreover, they can reach the mucosal surface and induce colitis in hosts suffering genetic or diet-based mucus dysfunction. In part, this susceptibility reflects the important role played by mucus in the production of SCFA, suggesting potential therapeutic approaches for patients suffering UC.

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CCC, CIHR

Disclosure of Interest

None Declared

NEDD4 ameliorates myocardial reperfusion injury by preventing macrophages pyroptosis

OBJECTIVES

The inflammatory cascade and cell death post-myocardial ischemia reperfusion (MI/R) are very complex. Despite the understanding that macrophage inflammation has a pivotal role in the pathophysiology of MI/R, the contribution of macrophage inflammatory signals in tailoring the function of vascular endothelium remains unknown.

MATERIALS AND METHODS

In the present study, we analyzed the effects of NEDD4 on the NLRP3 inflammasome activation-mediated pyroptosis in vitro after an acute pro-inflammatory stimulus and in vivo in a MI/R mouse model. TTC and Evan's blue dye, Thioflavin S, immunohistochemistry staining, and ELISA were performed in wild-type and NEDD4 deficiency mice. THP-1 cells were transfected with si-NEDD4 or si-SF3A2. HEK293T cells were transfected with NEDD4 or SF3A2 overexpression plasmid. ELISA analyzed the inflammatory cytokines in the cell supernatant. The levels of NEDD4, SF3A2, and NLRP3/GSDMD pathway were determined by Western blot. Protein interactions were evaluated by immunoprecipitation. The protein colocalization in cells was monitored using a fluorescence microscope.

RESULTS

NEDD4 inhibited NLRP3 inflammasome activation and pyroptosis in THP-1 cells treated with lipopolysaccharide (LPS) and nigericin (Nig). Mechanistically, NEDD4 maintained the stability of NLRP3 through direct interaction with the SF3A2, whereas the latter association with NLRP3 indirectly interacted with NEDD4 promoting proteasomal degradation of NLRP3. Deletion of NLRP3 expression further inhibited the caspase cascade to induce pyroptosis. Interestingly, inhibiting NLRP3 inflammasome activation in THP-1 cells could prevent cardiac microvascular endothelial cells (CMECs) injury. In addition, NEDD4 deficiency decreased animal survival and increased myocardial infarct size, no-reflow area, and promoted macrophages infiltration post-MI/R.

CONCLUSIONS

NEDD4 could be a potential therapeutic target in microvascular injury following myocardial reperfusion. Video Abstract.

[Progress in perioperative management of ABO-incompatible pediatric liver transplantation]

ABO incompatible(ABO-I) liver grafts will affect the prognosis of liver transplantation. With the improvement of perioperative treatment,including plasma exchange,rituximab,splenectomy,etc.,the prognosis of ABO-I liver transplantation has been greatly improved. Because children's immune systems are not fully developed,the perioperative management of ABO-I pediatric liver transplantation is significantly different from that of adults. Reducing the perioperative anti-donor ABO antibody titer is the key to the perioperative management of ABO-I liver transplantation. This article summarizes literatures on the perioperative management of ABO-I pediatric liver transplantation, including the perioperative anti-rejection regimen in pediatric recipients of different ages, splenectomy, postoperative monitoring and postoperative complications, etc.

Low-dimensional nanomaterials as an emerging platform for cancer diagnosis and therapy

The burden of cancer is increasing, being widely recognized as one of the main reasons for deaths among humans. Despite the tremendous efforts that have been made worldwide to stem the progression and metastasis of cancer, morbidity and mortality in malignant tumors have been clearly rising and threatening human health. In recent years, nanomedicine has come to occupy an increasingly important position in precision oncotherapy, which improves the diagnosis, treatment, and long-term prognosis of cancer. In particular, LDNs with distinctive physicochemical capabilities have provided great potential for advanced biomedical applications, attributed to their large surface area, abundant surface binding sites, and good cellular permeation properties. In addition, LDNs can integrate CT/MR/US/PAI and PTT/PDT/CDT/NDDS into a multimodal theranostic nanoplatform, enabling targeted therapy and efficacy assessments for cancer. This review attempts to concisely summarize the classification and major properties of LDNs. Simultaneously, we particularly emphasize their applications in the imaging, diagnosis, and treatment of cancerous diseases.

[Clinical characteristics of 18 children with chronic nonbacterial osteomyelitis]

Objective: To investigate the clinical features of children with chronic nonbacterial osteomyelitis (CNO), and raise awareness among clinicians. Methods: In this retrospective study, 18 patients with CNO who were diagnosed in Children's Hospital of Fudan University from January 2015 to December 2021 were included. Results: Eighteen children with CNO (12 males, 6 females) were identified. Their age at onset was 9 (5, 11) years, the delay in diagnosis was 2 (1, 6) months, and follow-up-was 17 (8, 34) months. The most common symptoms were fever in 14 children, as well as bone pain and (or) arthralgia in 14 children. In terms of laboratory results, normal white blood cell counts were observed at onset in 17 patients; increased erythrocyte sedimentation rate (ESR) in all patients; increased C reactive protein (CRP) over the normal value in 14 patients. Of the 18 patients, 2 had positive antinuclear antibodies, while none had positive human leukocyte antigen-B27 or rheumatoid factor. Imaging examination revealed that all the patients had symmetrical and multifocal skeletal lesions. The number of structural lesions detected by imaging investigation was 8 (6, 11). The most frequently affected bones were tibia in 18 patients and femur in 17 patients. Bone biopsy was conducted in 14 patients and acute or chronic osteomyelitis manifested with inflammatory cells infiltration were detected. Magnetic resonance imaging (MRI) found bone lesions in all the patients and bone scintigraphy were positive in 13 patients. All the patients were treated with nonsteroidal anti-inflammatory drugs, among whom 10 cases also treated with oral glucocorticoids, 9 cases with traditional disease modifying anti-rheumatic drugs, 8 cases with bisphosphonates and 6 cases with tumor necrosis factor inhibitors. The pediatric chronic nonbacterial osteomyelitis disease activity score, increased by 70% or more in 13 patients within the initial 6-month follow-up. Conclusions: The clinical manifestations of CNO are lack of specificity. The first symptom of CNO is fever, with or without bone pain and (or) arthralgia, with normal peripheral blood leukocytes, elevated CRP and (or) ESR. Whole body bone scanning combined with MRI can early detect osteomyelitis at subclinical sites, and improve the diagnostic rate of CNO.

Ablation index-guided high-power ablation for superior vena cava isolation in patients with atrial fibrillation

Background

The strategy of ablation index (AI)-guided high-power ablation seems to be a novel strategy for performing pulmonary vein isolation (PVI). An AI-guided high-power ablation strategy was used in this study to determine whether superior vena cava isolation (SVCI) after PVI was feasible and safe for patients with AF.

Methods

Data from 53 patients with AF were collected. Mapping and ablation of SVC were performed. The applied power was set at 45 W and the procedure was guided by AI. The SVC was divided into six segments in a cranial view. The RF applications and AI values in different segments were compared and analyzed. Using receiver operating characteristic (ROC) analysis, the diagnostic accuracy of AI value for predicting segment block was evaluated.

Results

Electrical SVCIs were successfully achieved in all patients. SVCI was performed by segment ablation in most cases, with RF applications in different segments. The mean AI value in non-lateral walls was higher than that of the lateral wall (392 ± 28 vs. 371 ± 37, P < 0.001). Acutely blocked sites had significantly larger AI values compared with no-blocked sites (390 ± 30 vs. 343 ± 23, P < 0.001). The optimal AI cut-off value for non-lateral segments was 379 (sensitivity: 75.9%, specificity: 100%) and for lateral segments was 345 (sensitivity: 82.3%, specificity: 100%).

Conclusion

The AI values were predictive of the acute conduction block of SVCI. With AI values of 345 and 379, respectively, conduction block was achieved in the lateral walls at a lower level than in the non-lateral walls.

Effect of ventilation mode on postoperative pulmonary complications following lung resection surgery: a randomised controlled trial

The effect of intra-operative mechanical ventilation modes on pulmonary outcomes after thoracic surgery with one-lung ventilation has not been well established. We evaluated the impact of three common ventilation modes on postoperative pulmonary complications in patients undergoing lung resection surgery. In this two-centre randomised controlled trial, 1224 adults scheduled for lung resection surgery with one-lung ventilation were randomised to one of three groups: volume-controlled ventilation; pressure-controlled ventilation; and pressure-control with volume guaranteed ventilation. Enhanced recovery after surgery pathways and lung-protective ventilation protocols were implemented in all groups. The primary outcome was a composite of postoperative pulmonary complications within the first seven postoperative days. The outcome occurred in 270 (22%), with 87 (21%) in the volume control group, 89 (22%) in the pressure control group and 94 (23%) in the pressure-control with volume guaranteed group (p = 0.831). The secondary outcomes also did not differ across study groups. In patients undergoing lung resection surgery with one-lung ventilation, the choice of ventilation mode did not influence the risk of developing postoperative pulmonary complications. This is the first randomised controlled trial examining the effect of three ventilation modes on pulmonary outcomes in patients undergoing lung resection surgery.

Closing Post-orthodontic Spaces Between Anterior Teeth Using Sequential 3D-printed Direct Composite Injection Guides

Restorative treatment of anterior teeth is sometimes required to improve esthetic and functional occlusal outcomes of orthodontic therapy. This case report presents a direct, noninvasive approach to close post-orthodontic gaps in anterior teeth using a 3D-printed composite resin injection guide with a full digital workflow. The composite injection technique using 3D-printed guides is a full digital workflow that can transfer the design precisely, save chair time, and simplify the direct composite restoration procedure.

[A prospective cohort study on socioeconomic status and risk of all-cause mortality among patients with type 2 diabetes based on latent class analysis]

Objective: To investigate the relationship between socioeconomic status (SES) and all-cause mortality in patients with type 2 diabetes. Methods: A total of 17 553 patients with type 2 diabetes were recruited under the National Basic Public Health Service Project in Changshu county, Qingjiangpu district, and Huai'an district in Huai'an city of Jiangsu province as participants. Latent class analysis was applied to classify the individuals based on five socioeconomic indicators. Then, Cox proportional hazards regression models were used to estimate the associations of different levels of SES with all-cause mortality, and stratified analysis was performed according to age and area. Results: Among 100 529.08 person-years of the fo1low-up, the median follow-up time was 5.7 years, and 1 829 deaths occurred during the follow-up period. According to the relevant results of the latent class model, the model of the "three classes" was the best. The related population was then divided into low SES (8 256 people, 47.0%), medium SES (4 427 people, 25.2%), and high SES groups (4 870 people, 27.8%). Compared to patients with high SES, the multivariate-adjusted hazard ratio (95%CI) of all-cause mortality associated with low SES for males and females were 1.84 (1.53-2.21) and 1.41 (1.51-1.72), respectively. Stratified analysis showed that the hazard ration (95%CI) of all-cause mortality associated with low SES for males and females were 1.99 (1.12-2.95) and 2.01 (1.20-3.23), respectively, in people younger than 60 years old, and were 1.90 (1.57-2.31) and 1.40 (1.13-1.73) in people over 60 years old. The HR values (95%CI) for all-cause mortality associated with low SES for the male and females were 1.54 (1.17-2.04) and 1.27 (1.02-1.59) in the urban population with 2.11 (1.55-2.85) and 2.64 (1.17-3.35) in rural population, respectively. Conclusions: Lower SES increased the risk of all-cause mortality in type 2 diabetic patients, which is more significant in younger and rural populations.

Association of usual walking with mortality in oldest old adults aged 85 years and older: a nationwide senior cohort study

Background

Current guidelines recommend moderate to vigorous intensity physical activity (MVPA) for health benefit in adults. However, it is difficult to meet the recommended minimum MVPA in “oldest old” aged over 85. Although walking is simple and easy exercise for oldest old, research on the association between walking and mortality in oldest old are lacking.

Purpose

To investigate the association between walking and the risk of all-cause and cardiovascular mortality among older adults aged 85 years and older.

Methods

7047 participants aged 85 or older underwent the Korean National Health Screening Program, including self-administered questionnaire for physical activity. Reported frequency per week of walking for at least 30 minutes increment was used to classify hours of walking per week. We computed multivariable-adjusted hazard ratios for walking and mutually adjusted for MVPA in relation to all-cause and cardiovascular mortality.

Results

The proportions of participants who engaged in walking, moderate- and vigorous-intensity physical activity were 42.5% (2996/7047), 14.7% (1037/7047) and 11.0% (773/7047), respectively. Only 7.6% (538/7047) of participants met the guidelines recommended minimum MVPA. Compared to inactive individuals, those who walked at least 1 hour per week had lower all-cause (HR 0.60 [95% CI, 0.50–0.74]) and cardiovascular mortality risk (HR 0.61 [95% CI, 0.42–0.89]). Walking 1 hour per week was still significant associated with reduction of risk for all-cause (HR 0.50 [95% CI, 0.40–0.61]) and cardiovascular mortality (HR 0.46 [95% CI, 0.30–0.70]) among participants who reported only walking without any MVPA.

Conclusions

1 hour a week of walking might be of benefit for all-cause and cardiovascular mortality in aged over 85 years, even without MVPA. Promoting walking may be a way to help oldest old avoid inactivity and encourage an active lifestyle for all-cause and cardiovascular mortality risk reduction.

Funding Acknowledgement

Type of funding sources: None.

[A multicenter epidemiological study of acute bacterial meningitis in children]

Objective: To analyze the clinical epidemiological characteristics including composition of pathogens , clinical characteristics, and disease prognosis acute bacterial meningitis (ABM) in Chinese children. Methods: A retrospective analysis was performed on the clinical and laboratory data of 1 610 children <15 years of age with ABM in 33 tertiary hospitals in China from January 2019 to December 2020. Patients were divided into different groups according to age,<28 days group, 28 days to <3 months group, 3 months to <1 year group, 1-<5 years of age group, 5-<15 years of age group; etiology confirmed group and clinically diagnosed group according to etiology diagnosis. Non-numeric variables were analyzed with the Chi-square test or Fisher's exact test, while non-normal distrituction numeric variables were compared with nonparametric test. Results: Among 1 610 children with ABM, 955 were male and 650 were female (5 cases were not provided with gender information), and the age of onset was 1.5 (0.5, 5.5) months. There were 588 cases age from <28 days, 462 cases age from 28 days to <3 months, 302 cases age from 3 months to <1 year of age group, 156 cases in the 1-<5 years of age and 101 cases in the 5-<15 years of age. The detection rates were 38.8% (95/245) and 31.5% (70/222) of Escherichia coli and 27.8% (68/245) and 35.1% (78/222) of Streptococcus agalactiae in infants younger than 28 days of age and 28 days to 3 months of age; the detection rates of Streptococcus pneumonia, Escherichia coli, and Streptococcus agalactiae were 34.3% (61/178), 14.0% (25/178) and 13.5% (24/178) in the 3 months of age to <1 year of age group; the dominant pathogens were Streptococcus pneumoniae and the detection rate were 67.9% (74/109) and 44.4% (16/36) in the 1-<5 years of age and 5-<15 years of age . There were 9.7% (19/195) strains of Escherichia coli producing ultra-broad-spectrum β-lactamases. The positive rates of cerebrospinal fluid (CSF) culture and blood culture were 32.2% (515/1 598) and 25.0% (400/1 598), while 38.2% (126/330)and 25.3% (21/83) in CSF metagenomics next generation sequencing and Streptococcus pneumoniae antigen detection. There were 4.3% (32/790) cases of which CSF white blood cell counts were normal in etiology confirmed group. Among 1 610 children with ABM, main intracranial imaging complications were subdural effusion and (or) empyema in 349 cases (21.7%), hydrocephalus in 233 cases (14.5%), brain abscess in 178 cases (11.1%), and other cerebrovascular diseases, including encephalomalacia, cerebral infarction, and encephalatrophy, in 174 cases (10.8%). Among the 166 cases (10.3%) with unfavorable outcome, 32 cases (2.0%) died among whom 24 cases died before 1 year of age, and 37 cases (2.3%) had recurrence among whom 25 cases had recurrence within 3 weeks. The incidences of subdural effusion and (or) empyema, brain abscess and ependymitis in the etiology confirmed group were significantly higher than those in the clinically diagnosed group (26.2% (207/790) vs. 17.3% (142/820), 13.0% (103/790) vs. 9.1% (75/820), 4.6% (36/790) vs. 2.7% (22/820), χ²=18.71, 6.20, 4.07, all P<0.05), but there was no significant difference in the unfavorable outcomes, mortility, and recurrence between these 2 groups (all P>0.05). Conclusions: The onset age of ABM in children is usually within 1 year of age, especially <3 months. The common pathogens in infants <3 months of age are Escherichia coli and Streptococcus agalactiae, and the dominant pathogen in infant ≥3 months is Streptococcus pneumoniae. Subdural effusion and (or) empyema and hydrocephalus are common complications. ABM should not be excluded even if CSF white blood cell counts is within normal range. Standardized bacteriological examination should be paid more attention to increase the pathogenic detection rate. Non-culture CSF detection methods may facilitate the pathogenic diagnosis.

[Outcome of pediatric-to-adult liver transplantation:a single-center study in China]

Objective: To explore the outcome of the pediatric-to-adult liver transplantation, including postoperative complications and relevant factors which affecting graft survival. Methods: Data of 55 patients undergoing pediatric-to-adult liver transplantation at the First Affiliated Hospital of Zhejiang University between January 2015 and August 2021 were retrospectively analyzed. The donors consisted of 34 males and 21 females, and the age was (11.8±4.7) years (range: 1 to 17 years). Among the cases,17 cases (30.9%) were donation of brain death,32 cases (58.2%) were donation of cardiac death, and 6 cases (10.9%) were donation after brain death plus cardiac death. The recipients consisted of 32 males and 23 females, and the age was (51.6±10.1) years (range: 27 to 70 years). Among the recipients,10 cases (18.2%) were ABO-incompatible liver transplantation.The influencing factors of early graft survival were analyzed by Student t test,Mann-Whitney U test or χ² test,respectively.Survival curve was drawn by Kaplan-Meier method.Logistic multivariate analysis was used to analyze the independent relevant factors of early postoperative graft loss. Results: Up to October 31,2021,the follow-up time (M(IQR)) was 36.0(43.1)months(range:5.9 to 81.7 months).There were 13 cases with graft loss (two of them underwent re-transplantation due to acute liver failure).The monofactor analysis indicated that cold ischemia time and donor-recipient blood group matching were the relevant factors affecting the early graft survival rate(both P<0.05).Logistic multivariate analysis showed that cold ischemia time and history of recipient gastrointestinal bleeding were independent relevant factors(both P<0.05).Postoperative hepatic artery thrombosis occurred in 3 cases(5.5%), portal vein thrombosis diagnosed in 4 cases(7.3%), portal vein stenosis occurred in 2 cases(3.6%),biliary complications diagnosed in 7 cases(12.7%), and small liver syndrome was found in 8 cases(14.5%). Conclusions: Adult liver transplantation with pediatric donor liver is an effective method to treat end-stage liver disease.Cold ischemia time and history of recipient gastrointestinal bleeding were independent relevant factors for the early graft survival.

Epigallocatechin gallate inhibits SNARE-dependent membrane fusion by blocking trans-SNARE assembly

Insulin secretion is a signal-triggered process that requires membrane fusion between the secretory granules and plasma membrane in pancreatic β cells. The exocytosis of insulin is mediated by target-soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs) on the plasma membrane and vesicle-SNAREs on the vesicles, which assemble into a quaternary trans-SNARE complex to initiate the fusion. Expression of fusion proteins is reduced in the islets of patients with type II diabetes, indicating that SNARE-mediated fusion defect is closely related to insulin-based metabolic diseases. Previous studies have suggested that epigallocatechin gallate (EGCG) has an inhibitory effect on membrane fusion. In the present study, we performed in vitro reconstitution assays to unravel the molecular mechanisms of EGCG in SNARE-mediated insulin secretory vesicle fusion. Our data show that EGCG efficiently inhibits insulin secretory SNARE-mediated membrane fusion. Mechanistic studies indicated that EGCG blocks the formation of the trans-SNARE complex. Furthermore, calcium/synaptotagmin-7-stimulated fusion kinetics were largely reduced by EGCG, confirming that it is a potential regulator of SNARE-dependent insulin secretion. Our findings suggest that the trans-SNARE complex might be a promising target for controlling SNARE-dependent vesicle fusion.

Assembly-promoting protein Munc18c stimulates SNARE-dependent membrane fusion through its SNARE-like peptide

Intracellular vesicle fusion requires the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and their cognate Sec1/Munc18 (SM) proteins. How SM proteins act in concert with trans-SNARE complexes to promote membrane fusion remains incompletely understood. Munc18c, a broadly distributed SM protein, selectively regulates multiple exocytotic pathways, including GLUT4 exocytosis. Here, using an in vitro reconstituted system, we discovered a SNARE-like peptide (SLP), conserved in Munc18-1 of synaptic exocytosis, is crucial to the stimulatory activity of Munc18c in vesicle fusion. The direct stimulation of the SNARE-mediated fusion reaction by SLP further supported the essential role of this fragment. Interestingly, we found SLP strongly accelerates the membrane fusion rate when anchored to the target membrane but not the vesicle membrane, suggesting it primarily interacts with t-SNAREs in cis to drive fusion. Furthermore, we determined the SLP fragment is competitive with the full-length Munc18c protein and specific to the cognate v-SNARE isoforms, supporting how it could resemble Munc18c’s activity in membrane fusion. Together, our findings demonstrate that Munc18c facilitates SNARE-dependent membrane fusion through SLP, revealing that the t-SNARE-SLP binding mode might be a conserved mechanism for the stimulatory function of SM proteins in vesicle fusion.

P02.01.B The telomere maintenance mechanism spectrum and its dynamics in gliomas

The activation of the telomere maintenance mechanism (TMM) is one of the critical drivers of cancer cell immortality. In gliomas, TERT expression and TERT promoter mutation are considered to reliably indicate telomerase activation, while ATRX mutation indicates alternative lengthening of telomeres (ALT). However, these relationships have not been extensively validated in tumor tissues. Here, we show through the direct measurement of telomerase activity and ALT in a large set of glioma samples that the TMM in glioma cannot be defined in the dichotomy of telomerase activity and ALT, regardless of TERT expression, TERT promoter mutation and ATRX mutation. Moreover, we observed that a considerable proportion of gliomas lack both telomerase activity and ALT (Neither group). And this Neither group exhibited evidence of slow growth potential. From a set of longitudinal samples from a separate cohort of glioma patients, we discovered that the TMM is not fixed but changes with glioma progression. Collectively, these results suggest that the TMM is a dynamic entity and that reflects the plasticity of the oncogenic biological status of tumor cells and that the TMM should be defined by the direct measurement of telomerase enzyme activity and evidence of ALT.

Seroprevalence of antibodies to classical swine fever virus and porcine reproductive and respiratory syndrome virus in healthy pigs in Hunan Province, China

Classical swine fever (CSF) and porcine reproductive and respiratory syndrome (PRRS) are responsible for major economic losses and represent a threat to the swine industry worldwide. Routine surveillance serology for CSF and PRRS viruses is critical to maintaining the health status of sow farms in Hunan Province, which is one of the top pig production provinces in China. The aim of our study was to investigate the serological statistics of CSF virus (CSFV) and PRRS virus (PRRSV) in Hunan Province. The cohort serum samples were collected from vaccinated and unvaccinated pigs. Our findings showed that the average rates of CSFV and PRRSV antibody seropositivity were 82.2% (95% CI: 80.1-84.3) and 84.8% (95% CI: 82.5-87.1), respectively, in the immunized group and that these rates were higher than those in the unvaccinated group (58.6% for CSFV and 47.8% for PRRSV). Additionally, the level of CSFV antibody in piglet serum declined gradually with age, whereas PRRSV-specific antibody level increased initially (1 to 2 weeks old) and then declined with age (2 to 4 weeks old). In summary, we investigated the difference in CSFV/PRRSV antibody levels among piglets at various weeks old (1 to 4 weeks) to further establish the duration of maternal immunity in piglets. In addition, routine monitoring of CSFV/PRRSV antibodies in immunized pigs was carried out to evaluate the efficacy of vaccination.

[A descriptive analysis of tea consumption in adult twins in China]

Objective: To describe the distribution characteristics of tea consumption in adult twins recruited in the Chinese National Twin Registry (CNTR) and provide clues to genetic and environmental influences on tea consumption. Methods: Enrolled in CNTR during 2010-2018, 25 264 twin pairs aged 18 years and above were included in subsequent analysis. Random effect models were used to estimate tea consumption in the population and regional distribution characteristics. The concordance rate of the behavior and difference in consumption volume of tea within pairs were also described. Results: The mean age of all subjects was (35.38±12.45) years old. The weekly tea consumers accounted for 17.0%, with an average tea consumption of (3.36±2.44) cups per day. The proportion of weekly tea consumers was higher among males, 50-59 years old, southern, urban, educated, and the first-born in the twin pair (P<0.05), and lower among unmarried individuals (P<0.001). Within-pair analysis showed that the concordance rate of tea consumption of monozygotic (MZ) twins was higher than that of dizygotic (DZ) twins and the overall heritability of tea consumption was 13.45% (11.38%-15.51%). Stratified by the characteristics mentioned above, only in males, the concordance rate of MZ showed a tendency to be greater than that of DZ (all P<0.05). The differences in consumption volume of tea within twin pairs were minor in MZ among males (P<0.05), while the differences were not significant in female twins. Conclusion: There were discrepancies in the distribution of tea consumption among twins of different demographic and regional characteristics. Tea consumption was mainly influenced by environmental factors and slightly influenced by genetic factors. The size of genetic factors varied with gender, age, and region, and gender was a potential modified factor.

[Value of metagenomic next-generation sequencing in the etiology diagnosis of bacterial meningitis in children]

Objective: To explore the value of metagenomic next-generation sequencing (mNGS) in the etiology diagnosis of bacterial meningitis in children. Methods: The etiological results of 189 children diagnosed with "bacterial meningitis" or "purulent meningitis" or "central nervous system infection" in the Children's Hospital of Fudan University from 1st January 2019 to 31st December 2020 were analyzed retrospectively. The cerebrospinal fluid (CFS) of the children with bacterial meningitis was detected by culture and mNGS respectively, and the difference of pathogen detection rate between the 2 methods was analyzed. According to the age at the time of visit, the children were divided into neonatal group (≤28 days of age) and non-neonatal group (>28 days of age), and χ² test was used to compare the positive rate between the 2 groups. Taking CFS culture as the gold standard, the sensitivity and specificity of mNGS in the diagnosing of bacterial meningitis in children were analyzed. Results: Among these 189 children with bacterial meningitis, 116 were males and 73 were females. A total of 76 strains of pathogens were detected in blood and (or) CSF cultures, of which 50 strains (65.8%) were Gram-positive bacteria; among those, 18 strains (23.7%) of Streptococcus agalactiae, 17 strains (19.7%) of Escherichia coli and 15 strains (19.7%) of Streptococcus pneumoniae were detected with higher detection rate. The infection rate of Gram-positive bacteria in the non-neonatal group was higher than that in the neonatal group (76.0% (38/50) vs. 50.0% (13/26), χ²=5.24, P=0.020).The same CSF samples of 48 cases were tested by mNGS and culture at the same time, and the detection rate of mNGS was higher than that of CSF culture (20 cases (41.7%) vs. 12 cases (25.0%), χ²=16.45, P<0.001). The consistency of mNGS and culture results was 79.2% (38/48), and the same pathogen was detected in 11 children with both positive mNGS and CSF culture. Taking the results of CSF culture as the gold standard, the sensitivity of mNGS in the diagnosing of bacterial meningitis was 91.7%, and the specificity was 75.0%. Conclusions: The mNGS technology can improve the pathogen detection rate of bacterial meningitis in children, and has a high consistency with CSF culture. In suspected cases where the pathogen cannot be identified by traditional methods, CSF mNGS should be considered timely.

Characteristics of Radiation-Related Intracranial Aneurysms: A Multicenter Retrospective Study

BACKGROUND AND PURPOSE

Intracranial aneurysms, a rare complication of radiation therapy, have been reported mainly in case reports or case series. We performed a multicenter, retrospective cohort study to investigate the characteristics of radiation-induced intracranial aneurysms.

MATERIALS AND METHODS

Data on 2641 patients with intracranial aneurysms were retrospectively collected from 3 hospitals between January 2005 and June 2014. An additional 1519 patients were recruited from a single center between July 2014 and March 2020. Aneurysms in patients with a history of radiation therapy for at least 6 months were defined as radiation-related aneurysms. Patients' demographic profiles, clinical characteristics, and aneurysm parameters detected on CTA were compared between radiation-related and control groups.

RESULTS

Of the 4160 patients, the average age was 57.9 (SD, 13.5) years, 2406 (57.8%) were women, 477 (11.5%) had multiple aneurysms, 3009 (72.3%) had SAH, and 34 (0.8%) had radiation-related aneurysms. The male-to-female ratio in the radiation-related group was significantly higher than that in the control group (2.4:1 versus 0.72:1, P = .001). The mean age of the radiation-related group was significantly younger than in the control group (51.4 [SD, 15.0] years versus 58.2 [SD, 13.5] years, P = .003). More patients in the radiation-related group presented with SAH than in the control group (without age and sex matching, 88.2% versus 72.2%, P = .037; with age and sex matching, 88.2% versus 58.8%, P = .006). Of the 4813 intracranial aneurysms, only 43 (0.9%) aneurysms were categorized as in the radiation-related group, whereas 4770 (99.1%) aneurysms constituted the control group. Compared with the control group, there was a significantly higher proportion of sidewall aneurysms (46.5% versus 32.3%, P = .048) and a predilection for aneurysms involving the ICA and posterior circulation arteries (72.1% versus 52.2%, P = .046) in the radiation-related group.

CONCLUSIONS

Compared with the control group, radiation-related aneurysms are more prone to occur in men and young patients, with a higher percentage of sidewall aneurysms located in the ICA and posterior circulation arteries. Furthermore, SAH is highly prevalent in patients with radiation-induced aneurysms, indicating that dedicated screening for aneurysms after radiation therapy is necessary, but further studies are needed to determine when and how to screen.

Ordered stereom structure in sea urchin tubercles: High capability for energy dissipation

Tubercles in sea urchin shells serve as a base on the test plates connecting the spine; these undergo compressive or impact stress from the spines. As the volume fraction of the ordered stereom structure in a tubercle increases, the compressive load-displacement curves are gradually characterized by the typical behavior of ceramic foams. Although this ordered stereom structure only exhibits an average porosity of 50.6%, it also exhibits high fracture resistance and energy dissipation capacity. Such remarkable behavior of the ordered stereom structure is attributed to its unique hierarchical microstructure. Specifically, at the macroscale, the stereom structure is periodic. It has uniformly distributed pores that are typically round, which can effectively reduce the stress concentration around the pores, and the ordered arrangement of the trabeculae along the axial direction of the tubercle bears the most compressive stress. The trabeculae present a bottleneck shape with a specific dimension, ensuring the best fracture resistance with a relatively higher porosity. Furthermore, crack deflection in the trabeculae changes the local fracture mode of the mineral, thereby increasing the crack surface area. STATEMENT OF SIGNIFICANCE: The connecting bases of the spines in sea urchin shell, known as tubercle, effectively undergo the compressive stress or impact stress from the spines. An ordered stereom structure is found in the tubercle, and it shows an excellent fracture resistance and energy dissipation capacity. Such a fantastic behavior of the ordered stereom structure mainly takes advantage of its unique hierarchical microstructure. The stereom structure presents a periodic structure on macroscale, the trabeculae show a bottleneck shape with a specific dimension to guarantee the best fracture resistance with a relatively higher porosity, and the soft fillers among CaCO₃ nanoparticles in a trabecula cause consecutive crack deflections.

Scintillation light detection in the 6-m drift-length ProtoDUNE Dual Phase liquid argon TPC

DUNE is a dual-site experiment for long-baseline neutrino oscillation studies, neutrino astrophysics and nucleon decay searches. ProtoDUNE Dual Phase (DP) is a 6  ×  6  ×  6 m 3 liquid argon time-projection-chamber (LArTPC) that recorded cosmic-muon data at the CERN Neutrino Platform in 2019-2020 as a prototype of the DUNE Far Detector. Charged particles propagating through the LArTPC produce ionization and scintillation light. The scintillation light signal in these detectors can provide the trigger for non-beam events. In addition, it adds precise timing capabilities and improves the calorimetry measurements. In ProtoDUNE-DP, scintillation and electroluminescence light produced by cosmic muons in the LArTPC is collected by photomultiplier tubes placed up to 7 m away from the ionizing track. In this paper, the ProtoDUNE-DP photon detection system performance is evaluated with a particular focus on the different wavelength shifters, such as PEN and TPB, and the use of Xe-doped LAr, considering its future use in giant LArTPCs. The scintillation light production and propagation processes are analyzed and a comparison of simulation to data is performed, improving understanding of the liquid argon properties.

Feasibility of an ultra-low dose contrast media protocol for coronary CT angiography

AIM

To evaluate the feasibility of an ultra-low volume contrast media (CM) protocol for coronary computed tomography angiography (CTA).

MATERIALS AND METHODS

In total, 214 patients receiving coronary CTA were enrolled prospectively and divided into group A (n=107) receiving a conventional dose of CM and group B (n=107) receiving an ultra-low dose. CT values of the right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX) were measured and radiation doses recorded. The image quality was compared between the groups. Changes in renal function indices and proteinuria before, 24, and 72 hours after coronary CTA among those with chronic kidney disease (CKD) were also assessed.

RESULTS

There were significant differences in CT values and radiation doses between groups A and B. In group A, the average RCA, LAD, and LCX CT values were 412.5 ± 79.2, 423.5 ± 73.7, and 422.0 ± 88.1 HU, respectively. In group B, the average RCA, LAD, and LCX CT values were 275.2 ± 16.2, 277.8 ± 16.4, and 278.9 ± 16.5 HU, respectively. The radiation dose in the ultra-low protocol recipients (118.70 ± 18.52 mGy·cm) was significantly lower than that used in conventional coronary CTA (131.75 ± 20.96 mGy·cm). The image quality of group B was comparable to that of group A, satisfying the diagnostic requirement. In patients with mild CKD, there were no significant differences in renal functions after coronary CTA.

CONCLUSION

An ultra-low CM protocol was established for coronary CTA, providing comparable image quality and diagnostic yields but significantly lower radiation dose compared with a conventional protocol. This new protocol might be applicable to patients with mild CKD.

Templated freezing: a simple method may increase gripping force of the clamp on the tendon

Purpose

To evaluate the effectiveness of combining a customized mold with frozen conventional clamps against other freezing and non-freezing methods.

Methods

Forty-five porcine and 45 chicken tendons were evenly divided into five groups (n = 9 + 9/group): control group, non-freezing with gauze placed between tendon and clamp (gauze), non-freezing with suture fixation at tendon ends (suture), freezing with dry ice pocket placed at the clamps (pocket), and freezing using a templated liquid nitrogen clamp with a customized mold (mold). Tension tests were used to measure failure modes and loads.

Result

Slippage and avulsion were observed in non-freezing groups with significantly lower failure loads compared to freezing methods. With freezing, rupture occurred near the central point only in the mold group. The failure loads for porcine tendons in the mold group were higher (2121.651 ± 73.101 N) than the pocket group (1746.337 ± 68.849 N). The failure loads of chicken tendons in the mold (243.552 ± 15.881 N) and pocket groups (260.647 ± 22.161 N) were not statistically different.

Conclusion

Freezing clamps represent the better choice for soft tissue clamping. The customized mold method could improve gripping effectiveness.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03209-y.