Objective. To improve the safety and reliability of gastric ulcer treatment, the emergence of digestive endoscopy technology in recent years has become a conventional method for the diagnosis of ...peptic ulcer bleeding. Endoscopic characteristics can judge the severity of patients more accurately and comprehensively, provide a basis for follow-up treatment, and judge the prognosis. Methods. 298 patients with a suspected gastric ulcer who underwent laryngeal gastroduodenal endoscopy and confirmed gastroduodenal ulcer in our hospital in recent half a year were randomly selected. Olympus cv-170 electronic gastroscope machine was used to carry out gastroscopy for patients with gastric ulcers, analyze, and judge the number of bleeding cases in different stages of treatment, such as lesion type, lesion location, patient age, and gender. The statistics of bleeding cycle and bleeding volume, prognosis recovery, and the correlation of different risk levels were analyzed. Results. After examination and diagnosis, the patients were followed up for one year. According to the number of bleeding cases, bleeding cycle, and bleeding volume of patients with different ulcer locations in the acute stage, healing stage, and scar stage, the distribution of bleeding cases of different ulcer locations in different stages was roughly the same, and there was no significant difference. The proportion of bleeding cases in the acute stage was the highest, while the proportion in the healing stage was the lowest. The number of bleeding cases, bleeding cycle, bleeding volume, and related symptoms in patients with gastric ulcers during the treatment were significantly correlated with those in the acute stage, healing stage, and scar stage. There was no significant difference in the distribution of bleeding in one year among different stages of ulcer in the same age group, however, the bleeding in one year would be more serious with the increase of age in different age groups. Gender differences have a great impact on the bleeding of the ulcer within one year. It usually shows that the bleeding of ulcers in males is more serious than that in females. Conclusion. The location and pathological development of gastric ulcers can be found in time through gastroscopy, and the status of gastroscopy can be analyzed. Most gastric ulcers are acute bleeding. The amount of bleeding has little correlation with the stage of gastric ulcer, and it is related to the location of bleeding. The older the age, the greater the amount of bleeding, and the amount of bleeding in men is greater than that in women. In the treatment of gastric ulcers, gastroscopy, as a doctor’s examination and treatment method, effectively improves the safety and reliability of clinical treatment of gastric ulcer bleeding and reduces the adverse risk.
α-Amanitin is one of the primary toxins produced by the poisonous mushroom genus, Amanita. Because it is odorless and tasteless, it is an important cause of death from the consumption of ...misidentified mushrooms. To study the thermal stability of α-amanitin, novel cell-based assays were developed to measure the toxin’s activity, based on the inhibition of RNA polymerase II by α-amanitin. First, an MTT–formazan cell viability assay was used to measure the biological activity of α-amanitin through the inhibition of cellular activity. This method can detect 10 μg/mL of α-amanitin in a time-dependent manner. Second, a more sensitive quantitative PCR approach was developed to examine its inhibition of viral replication. The new RT-qPCR assay enabled the detection of 100 ng/mL. At this level, α-amanitin still significantly reduced adenovirus transcription. Third, a simpler GFP expression-based assay was developed with an equal sensitivity to the RT-qPCR assay. With this assay, aqueous α-amanitin heated at 90 °C for 16 h or treated in the microwave for 3 min retained its biological activity when tested in HEK293 cells, but a slight reduction was observed when tested in Vero cells. Beyond detecting the activity of α-amanitin, the new method has a potential application for detecting the activity of other toxins that are RNA polymerase inhibitors.
Shiga toxin (Stx) is the key virulent factor in Shiga toxin-producing Escherichia coli (STEC). To date, three Stx1 subtypes and seven Stx2 subtypes have been described in E. coli, which differed in ...receptor preference and toxin potency. Here, we identified a novel Stx2 subtype designated Stx2h in E. coli strains isolated from wild marmots in the Qinghai-Tibetan plateau, China. Stx2h shares 91.9% nucleic acid sequence identity and 92.9% amino acid identity to the nearest Stx2 subtype. The expression of Stx2h in type strain STEC299 was inducible by mitomycin C, and culture supernatant from STEC299 was cytotoxic to Vero cells. The Stx2h converting prophage was unique in terms of insertion site and genetic composition. Whole genome-based phylo- and patho-genomic analysis revealed STEC299 was closer to other pathotypes of E. coli than STEC, and possesses virulence factors from other pathotypes. Our finding enlarges the pool of Stx2 subtypes and highlights the extraordinary genomic plasticity of E. coli strains. As the emergence of new Shiga toxin genotypes and new Stx-producing pathotypes pose a great threat to the public health, Stx2h should be further included in E. coli molecular typing, and in epidemiological surveillance of E. coli infections.
Multiple sclerosis (MS) is a chronic disease that is characterized by demyelination and axonal damage in the central nervous system. Cognitive deficits are recognized as one of the features of MS, ...and these deficits affect the patients' quality of life. Increasing evidence from experimental autoimmune encephalomyelitis (EAE), the animal model of MS, has suggested that EAE mice exhibit hippocampal impairment and cognitive deficits. However, the underlying mechanisms are still unclear. The NLRP3 inflammasome is a key contributor to neuroinflammation and is involved in the development of MS and EAE. Activation of the NLRP3 inflammasome in microglia is fundamental for subsequent inflammatory events. Activated microglia can convert astrocytes to the neurotoxic A1 phenotype in a variety of neurological diseases. However, it remains unknown whether the NLRP3 inflammasome contributes to cognitive deficits and astrocyte phenotype alteration in EAE. In this study, we demonstrated that severe memory deficits occurred in the late phase of EAE, and cognitive deficits were ameliorated by treatment with MCC950, an inhibitor of the NLRP3 inflammasome. In addition, MCC950 alleviated hippocampal pathology and synapse loss. Astrocytes from EAE mice were converted to the neurotoxic A1 phenotype, and this conversion was prevented by MCC950 treatment. IL-18, which is the downstream of NLRP3 inflammasome, was sufficient to induce the conversion of astrocytes to the A1 phenotype through the NF-κB pathway. IL-18 induced A1 type reactive astrocytes impaired hippocampal neurons through the release of complement component 3 (C3). Altogether, our present data suggest that the NLRP3 inflammasome plays an important role in cognitive deficits in EAE, possibly via the alteration of astrocyte phenotypes. Our study provides a novel therapeutic strategy for hippocampal impairment in EAE and MS.
We report a case of murine typhus in China caused by Rickettsia typhi and diagnosed by nanopore targeted sequencing of a bronchoalveolar lavage fluid sample. This case highlights that nanopore ...targeted sequencing can effectively detect clinically unexplained infections and be especially useful for detecting infections in patients without typical signs and symptoms.
Shiga toxin-producing Escherichia coli (STEC) O145 is a major serotype associated with severe human disease. Production of Shiga toxins (Stxs), especially Stx2a, is thought to be correlated with STEC ...virulence. Since stx genes are located in prophages genomes, induction of prophages is required for effective Stxs production. Here, we investigated the production of Stxs in 12 environmental STEC O145:H28 strains under stresses STEC encounter in natural habitats and performed comparative analysis with two O145:H28 clinical strains, one linked to a 2010 U.S. lettuce-associated outbreak (RM13514) and the other linked to a 2007 Belgium ice cream-associated outbreak (RM13516). Similar to the outbreak strains, all environmental strains belong to Sequence Type (ST)-78 using the EcMLST typing scheme. Although all Stx1a-prophages were grouped together, variations in Stx1a production were observed prior to or following the inductions. Among all stx2a positive environmental strains, only the Stx2a-prophage in cattle isolate RM9154-C1 was clustered with the Stx2a-prophages in RM13514, the Stx2a-phage induced from a STEC O104:H4 strain linked to the 2011 outbreak of enterohemorrhagic infection in Germany, and the Stx2a-prophage in STEC O157:H7 strain EDL933, a prototype of enterohemorrhagic E. coli. Furthermore, the Stx2a-prophage in RM9154-C1 shared the same chromosomal insertion site and carried the same antiterminator Q gene and the late promoter PR' as the Stx2a-prophage in RM13514. Following mitomycin C or enrofloxacin treatment, the production of Stx2a in RM9154-C1 was the highest among all environmental strains tested. In contrast, following acid challenge and recovery, the production of Stx2a in RM9154-C1 was the lowest among all the environmental strains tested, at a level comparable to the clinical strains. A significant increase in Stx2a production was detected in all strains when exposed to H2O2, although the induction fold was much lower than those by other inducers. This low-efficiency induction of Stx-prophages by H2O2, a natural inducer of Stx-prophages, supports the hypothesis of bacterial altruism in controlling Stxs production, a strategy that assures the survival of the STEC population as a whole by sacrificing a small fraction of cells for Stxs production and release. Differential induction of Stxs among strains carrying nearly identical Stx-prophages suggests a role of host bacteria in regulating Stxs production. Our study revealed diverse Stx-prophages in STEC O145:H28 strains that were genotypically indistinguishable. Identification of a cattle isolate harboring a Stx2a-prophage associated with high virulence supports the premise that cattle, a natural reservoir of STEC, serve as a source of hypervirulent STEC strains.
•Diverse Stx-prophages are present in STEC strains carrying the same genotype.•A cattle isolate harbors a Stx2a-prophage associated with high virulence.•The Stx2a-prophage associated with high virulence encodes a Q933 antiterminator.•Spontaneous production of Shiga toxin is strain-dependent following acid challenges.•H2O2 is capable of inducing the production of Stx1a and Stx2a in STEC O145:H28.
Outer membrane vesicles (OMVs) are important tools in bacterial virulence but their role in the pathogenesis of infections caused by enterohemorrhagic Escherichia coli (EHEC) O157, the leading cause ...of life-threatening hemolytic uremic syndrome, is poorly understood. Using proteomics, electron and confocal laser scanning microscopy, immunoblotting, and bioassays, we investigated OMVs secreted by EHEC O157 clinical isolates for virulence factors cargoes, interactions with pathogenetically relevant human cells, and mechanisms of cell injury. We demonstrate that O157 OMVs carry a cocktail of key virulence factors of EHEC O157 including Shiga toxin 2a (Stx2a), cytolethal distending toxin V (CdtV), EHEC hemolysin, and flagellin. The toxins are internalized by cells via dynamin-dependent endocytosis of OMVs and differentially separate from vesicles during intracellular trafficking. Stx2a and CdtV-B, the DNase-like CdtV subunit, separate from OMVs in early endosomes. Stx2a is trafficked, in association with its receptor globotriaosylceramide within detergent-resistant membranes, to the Golgi complex and the endoplasmic reticulum from where the catalytic Stx2a A1 fragment is translocated to the cytosol. CdtV-B is, after its retrograde transport to the endoplasmic reticulum, translocated to the nucleus to reach DNA. CdtV-A and CdtV-C subunits remain OMV-associated and are sorted with OMVs to lysosomes. EHEC hemolysin separates from OMVs in lysosomes and targets mitochondria. The OMV-delivered CdtV-B causes cellular DNA damage, which activates DNA damage responses leading to G2 cell cycle arrest. The arrested cells ultimately die of apoptosis induced by Stx2a and CdtV via caspase-9 activation. By demonstrating that naturally secreted EHEC O157 OMVs carry and deliver into cells a cocktail of biologically active virulence factors, thereby causing cell death, and by performing first comprehensive analysis of intracellular trafficking of OMVs and OMV-delivered virulence factors, we provide new insights into the pathogenesis of EHEC O157 infections. Our data have implications for considering O157 OMVs as vaccine candidates.
The prevalence of
-positive bacteria in 5,169 domestic animal-derived samples collected by USDA Food Safety and Inspection Service between October 2018 and May 2019 was investigated. A procedure ...including enriched broth culture and real-time PCR targeting
to
were used for the screening. Fifteen positive isolates were identified, including one plasmid-borne
-positive
strain, EC2492 (reported elsewhere) and 14
-positive strains from poultry (1), catfish (2), and chicken rinse (11) samples, resulting in an overall prevalence of
-positive bacteria 0.29% in all meat samples tested. Analysis of 16S rRNA and whole genome sequences revealed that all 14 strains belonged to
. Data from phylogenetic analysis of seven housekeeping genes, including
, and
, indicated that nine strains belonged to
and five strains belonged to
. Antimicrobial tests showed that almost all
-positive strains exhibited high resistance to colistin with MICs ≥ 128mg/L, except for one
strain, which showed a borderline resistance with a MIC of 2 mg/L. A segment containing two adjacent
and
lik
genes was found in two
and one
strains and a variety of IS-like elements were found in the flanking regions of this segment. A
-related lipid A phosphoethanolamine transferase gene was present in all 14
strains, while an additional
-related lipid A phosphoethanolamine transferase gene was found in 5
strains only. In addition to
genes, other antimicrobial resistance genes, including
,
,
,
,
,
,
,
, and
were observed in chromosomes of some
strains. The relative high prevalence of chromosome-borne
genes and the close proximity of various IS elements to these genes highlights the need for continued vigilance to reduce the mobility of these colistin-resistance genes among food animals.
Innovative 3D materials with the switchable wetting surface attract significant attention due to their application in oil/water separation. Herein, a fast pH‐responsive and highly effective melamine ...foam (MF) grafted with poly (2‐dimethylaminoethyl methacrylate) is prepared by surface‐initiated chain transfer radical polymerization. The as‐prepared MF displays superhydrophilic and superoleophobic surface in strong acid solution while it becomes superhydrophobic in neutral or basic solution. Therefore, it can be rapid to selectively absorb different types of oils from the oil–water mixture with a great absorption capacity of 54–117 g g−1 and automatically desorb oil in less than 60 s with a desorption efficiency of 99% (dichloromethane) in acid solution. Moreover, the as‐prepared MF possesses excellent recyclability, and the absorption capacity and the desorption efficiency are almost unchanged after 15 cycles. The pH‐sensitive MF with switchable wetting surfaces has great potential for the oily water separation.
The melamine foam (MF) modified by poly(2‐dimethylaminoethyl methacrylate) is successfully prepared by surface‐initiated chain transfer radical polymerization. The surface of the modified MF shows pH‐induced switchable wettability and the excellent oil absorption–desorption recyclability can be developed for applications in oil/water separation and oil recovery.
Shiga toxin (Stx) is the key virulence factor in Shiga toxin producing Escherichia coli (STEC), which can cause diarrhea and hemorrhagic colitis with life-threatening complications. Stx comprises two ...toxin types, Stx1 and Stx2. Several Stx1/Stx2 subtypes have been identified in E. coli, which are variable in sequences, toxicity and host specificity. Here, we report the identification of a novel Stx2 subtype, designated Stx2k, in E. coli strains widely detected from diarrheal patients, animals, and raw meats in China over time. Stx2k exhibits varied cytotoxicity in vitro among individual strains. The Stx2k converting prophages displayed considerable heterogeneity in terms of insertion site, genetic content and structure. Whole genome analysis revealed that the stx2k-containing strains were genetically heterogeneous with diverse serotypes, sequence types, and virulence gene profiles. The nine stx2k-containing strains formed two major phylogenetic clusters closely with strains belonging to STEC, enterotoxigenic E. coli (ETEC), and STEC/ETEC hybrid. One stx2k-containing strain harbored one plasmid-encoded heat-stable enterotoxin sta gene and two identical copies of chromosome-encoded stb gene, exhibiting STEC/ETEC hybrid pathotype. Our finding enlarges the pool of Stx2 subtypes and highlights the extraordinary genomic plasticity of STEC strains. Given the wide distribution of the Stx2k-producing strains in diverse sources and their pathogenic potential, Stx2k should be taken into account in epidemiological surveillance of STEC infections and clinical diagnosis.
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