Engineering hyperthermophilic pullulanase to efficiently utilize corn starch for production of maltooligosaccharides and glucose

Pullulanase is a starch-debranching enzyme that hydrolyzes side chain of starch, oligosaccharides and pullulan. Nevertheless, the limited activities of pullulanases constrain their practical application. Herein, the hyperthermophilic type II pullulanase from Pyrococcus yayanosii CH1 (PulPY2) was evolved by synergistically engineering the substrate-binding pocket and active-site lids. The resulting mutant PulPY2-M2 exhibited 5-fold improvement in catalytic efficiency (kcat/Km) compared to that of PulPY2. PulPY2-M2 was utilized to develop a one-pot reaction system for efficient production of maltooligosaccharides. The maltooligosaccharides conversion rate of PulPY2-M2 reached 96.1%, which was increased by 5.4% compared to that of PulPY2. Furthermore, when employed for glucose production, the glucose productivity of PulPY2-M2 was 25.4% and 43.5% higher than that of PulPY2 and the traditional method, respectively. These significant improvements in maltooligosaccharides and glucose production and the efficient utilization of corn starch demonstrated the potential of the engineered PulPY2-M2 in starch sugar industry.

A New-Generation Base Editor with an Expanded Editing Window for Microbial Cell Evolution In Vivo Based on CRISPR‒Cas12b Engineering

Base editors (BEs) are widely used as revolutionary genome manipulation tools for cell evolution. To screen the targeted individuals, it is often necessary to expand the editing window to ensure highly diverse variant library. However, current BEs suffer from a limited editing window of 5-6 bases, corresponding to only 2-3 amino acids. Here, by engineering the CRISPR‒Cas12b, the study develops dCas12b-based CRISPRi system, which can efficiently repress gene expression by blocking the initiation and elongation of gene transcription. Further, based on dCas12b, a new-generation of BEs with an expanded editing window is established, covering the entire protospacer or more. The expanded editing window results from the smaller steric hindrance compared with other Cas proteins. The universality of the new BE is successfully validated in Bacillus subtilis and Escherichia coli. As a proof of concept, a spectinomycin-resistant E. coli strain (BL21) and a 6.49-fold increased protein secretion efficiency in E. coli JM109 are successfully obtained by using the new BE. The study, by tremendously expanding the editing window of BEs, increased the capacity of the variant library exponentially, greatly increasing the screening efficiency for microbial cell evolution.

Simplified integration of optimal self-management behaviors is associated with improved HbA1c in patients with type 1 diabetes

PURPOSE

Living with type 1 diabetes requires burdensome and complex daily diabetes self-management behaviors. This study aimed to determine the association between integrated behavior performance and HbA1c, while identifying the behavior with the most significant impact on HbA1c.

METHODS

A simple and feasible questionnaire was used to collect diabetes self-management behavior in patients with type 1 diabetes (n = 904). We assessed six dimensions of behavior performance: continuous glucose monitor (CGM) usage, frequent glucose testing, insulin pump usage, carbohydrate counting application, adjustment of insulin doses, and usage of apps for diabetes management. We evaluated the association between these behaviors and HbA1c.

RESULTS

In total, 21.3% of patients performed none of the allotted behavior, while 28.5% of patients had a total behavior score of 3 or more. 63.6% of patients with a behavior score ≥ 3 achieved HbA1c goal, contrasting with only 30.4% of patients with a behavior score of 0-1. There was a mean 0.54% ± 0.05% decrease in HbA1c for each 1-unit increase in total behavior score after adjustment for age, family education and diabetes duration. Each behavior was independently correlated with a lower HbA1c level, with CGM having the most significant effect on HbA1c levels.

CONCLUSIONS

Six optimal self-management behaviors, especially CGM usage, were associated with improved glycemic control, emphasizing the feasibility of implementing a simplified version of DSMES in the routine clinical care.

REGISTRATION NUMBER

ClinicalTrials.gov Identifier: NCT03610984.

Effect of SIRT1 gene single-nucleotide polymorphisms on susceptibility to type 1 diabetes in a Han Chinese population

AIMS

SIRT1 deficiency has been associated with diabetes, and a variant of the SIRT1 gene has been found to be involved in human autoimmune diabetes; however, it is unclear whether this genetic variation exists in Han Chinese with type 1 diabetes (T1D) and whether it contributes to development of T1D. Therefore, we aimed to explore the association of the SIRT1 gene single-nucleotide polymorphisms (SNPs) rs10997866 and rs3818292 in a Han Chinese population with T1D.

METHODS

This study recruited 2653 unrelated Han Chinese individuals, of whom 1289 had T1D and 1364 were healthy controls. Allelic and genotypic distributions of SIRT1 polymorphisms (rs10997866 and rs3818292) were determined by MassARRAY. Basic characteristics, genotype and allele frequencies of selected SNPs were compared between the T1D patients and healthy controls. Further genotype-phenotype association analysis of the SNPs was performed on the T1D patients divided into three groups according to genotype. Statistical analyses included the chi-square test, Mann‒Whitney U test, Kruskal‒Wallis H test and logistic regression.

RESULTS

The allelic (G vs. A) and genotypic (GA vs. AA) distributions of SIRT1 rs10997866 were significantly different in T1D patients and healthy controls (P = 0.039, P = 0.027), and rs10997866 was associated with T1D susceptibility under dominant, overdominant and additive models (P = 0.026, P = 0.030 and P = 0.027, respectively). Moreover, genotype-phenotype association analysis showed the GG genotype of rs10997866 and the GG genotype of rs3818292 to be associated with higher titers of IA-2A (P = 0.013 and P = 0.038, respectively).

CONCLUSION

SIRT1 rs10997866 is significantly associated with T1D susceptibility, with the minor allele G conferring a higher risk of T1D. Moreover, SIRT1 gene rs10997866 and rs3818292 correlate with the titer of IA-2A in Han Chinese individuals with T1D.

[Progress and controversy in minimally invasive approach to radical cholecystectomy for gallbladder cancer]

Surgical treatment is one of the most important forms of treatment in patients with gallbladder cancer. With the development of minimally invasive technology, the feasibility, safety and efficacy of minimally invasive approaches such as laparoscopic or robotic-assisted radical cholecystectomy for gallbladder cancer have received continuous attention.For patients with an early T-stage (Tis or T1a), laparoscopic simple cholecystectomy is safe and economical, with a good prognosis for postoperative patients, and it has been widely accepted and performed. Radical resection of advanced gallbladder cancer requires resection of the gallbladder, its liver bed, and other neighboring invaded organs, as well as clearance of regional lymph nodes, which requires experienced gallbladder cancer treatment teams to strictly grasp the indications, select appropriate patients, and formulate a good surgical strategy to ensure the therapeutic effect. Meanwhile, robot-assisted radical resection for gallbladder cancer has been performed in a few centers and shows good clinical potential, but more high-quality studies are needed to further evaluate its value in gallbladder cancer treatment.

Carbapenem-resistant Klebsiella pneumoniae capsular types, antibiotic resistance and virulence factors in China: a longitudinal, multi-centre study

Epidemiological knowledge of circulating carbapenem-resistant Klebsiella pneumoniae (CRKP) is needed to develop effective strategies against this public health threat. Here we present a longitudinal analysis of 1,017 CRKP isolates recovered from patients from 40 hospitals across China between 2016 and 2020. Virulence gene and capsule typing revealed expansion of CRKP capsule type KL64 (59.5%) alongside decreases in KL47 prevalence. Hypervirulent CRKP increased in prevalence from 28.2% in 2016 to 45.7% in 2020. Phylogenetic and spatiotemporal analysis revealed Beijing and Shanghai as transmission hubs accounting for differential geographical prevalence of KL47 and KL64 strains across China. Moderate frequency capsule or O-antigen loss was also detected among isolates. Non-capsular CRKP were more susceptible to phagocytosis, attenuated during mouse infections, but showed increased serum resistance and biofilm formation. These findings give insight into CRKP serotype prevalence and dynamics, revealing the importance of monitoring serotype shifts for the future development of immunological strategies against CRKP infections.

[Genome-wide Mendelian randomization study of the pathogenic role of gut microbiota in benign biliary tract diseases]

Objective: To investigate the causal relationship between intestinal flora and benign biliary diseases by genome-wide Mendelian randomization. Methods: This is a retrospective observational study. The data from the genome-wide association study of the gut microbiota from 18 340 samples from the MiBioGen consortium were selected as the exposure group,and the data from the genome-wide association study of biliary tract diseases were obtained from the FinnGen consortium R8 as the outcome group. There were 1 491 cases of primary sclerosing cholangitis,32 894 cases of cholelithiasis,3 770 cases of acalculous cholecystitis,and 34 461 cases of cholecystitis. Single nucleotide polymorphisms were screened as instrumental variables,and the Mendelian randomization method was used to infer the causal relationship between exposures and outcomes. The inverse variance weighting method (IVW) was used as the main basis, supplemented by heterogeneity,pleiotropy and sensitivity tests. Results: Coprococcus 2 was associated with a reduced risk of cholelithiasis (IVW OR=0.88,95%CI:0.80 to 0.97,P=0.012) and cholecystitis (IVW OR=0.88,95%CI:0.80 to 0.97,P=0.011). Coprococcus 3 was associated with cholelithiasis (IVW OR=1.15,95%CI:1.02 to 1.30,P=0.019) and acalculous cholecystitis(IVW OR=1.48, 95%CI: 1.08 to 2.04,P=0.016) and cholecystitis (IVW OR=1.17, 95%CI: 1.02 to 1.33, P=0.020). Peptococcus was associated with an increased risk of cholelithiasis (IVW OR=1.08, 95%CI:1.02 to 1.13, P=0.005) and cholecystitis (IVW CI=1.07, 95%CI:1.02 to 1.13,P=0.010). Clostridiumsensustricto 1 was associated with an increased risk of cholelithiasis (IVW OR=1.16,95%CI:1.02 to 1.31, P=0.020) and cholecystitis (IVW OR=1.16, 95%CI:1.03 to 1.30, P=0.015). Eubacterium hallii was associated with an increased risk of primary sclerosing cholangitis (IVW OR=1.43, 95%CI: 1.03 to 1.99, P=0.033). Eubacterium ruminantium (IVW OR=0.87, 95%CI: 0.76 to 1.00, P=0.043) and Methanobrevibacter (IVW OR=0.81, 95%CI: 0.68 to 0.98, P=0.027) were associated with a reduced risk of acalculous cholecystitis. Conclusions: Eight intestinal bacterial genera maybe play pathogenic roles in benign biliary diseases. Eubacterium hallii can increase the risk of primary sclerosing cholangitis. Peptococcus and Clostridiumsensustricto 1 can increase the risk of cholelithiasis and generalized cholecystitis. Coprococcus 3 have multiple correlations with biliary stones and inflammation.

A metagenomic catalog of the early-life human gut virome

Early-life human gut microbiome is a pivotal driver of gut homeostasis and infant health. However, the viral component (known as "virome") remains mostly unexplored. Here, we establish the Early-Life Gut Virome (ELGV), a catalog of 160,478 non-redundant DNA and RNA viral sequences from 8130 gut virus-like particles (VLPs) enriched or bulk metagenomes in the first three years of life. By clustering, 82,141 viral species are identified, 68.3% of which are absent in existing databases built mainly from adults, and 64 and 8 viral species based on VLPs-enriched and bulk metagenomes, respectively, exhibit potentials as biomarkers to distinguish infants from adults. With the largest longitudinal population of infants profiled by either VLPs-enriched or bulk metagenomic sequencing, we track the inherent instability and temporal development of the early-life human gut virome, and identify differential viruses associated with multiple clinical factors. The mother-infant shared virome and interactions between gut virome and bacteriome early in life are further expanded. Together, the ELGV catalog provides the most comprehensive and complete metagenomic blueprint of the early-life human gut virome, facilitating the discovery of pediatric disease-virome associations in future.

[A multiscale carotid plaque detection method based on two-stage analysis]

OBJECTIVE

To develop a method for accurate identification of multiscale carotid plaques in ultrasound images.

METHODS

We proposed a two-stage carotid plaque detection method based on deep convolutional neural network (SM-YOLO).A series of algorithms such as median filtering, histogram equalization, and Gamma transformation were used to preprocess the dataset to improve image quality. In the first stage of the model construction, a candidate plaque set was built based on the YOLOX_l target detection network, using multiscale image training and multiscale image prediction strategies to accommodate carotid artery plaques of different shapes and sizes. In the second stage, the Histogram of Oriented Gradient (HOG) features and Local Binary Pattern (LBP) features were extracted and fused, and a Support Vector Machine (SVM) classifier was used to screen the candidate plaque set to obtain the final detection results. This model was compared quantitatively and visually with several target detection models (YOLOX_l, SSD, EfficientDet, YOLOV5_l, Faster R-CNN).

RESULTS

SM-YOLO achieved a recall of 89.44%, an accuracy of 90.96%, a F1-Score of 90.19%, and an AP of 92.70% on the test set, outperforming other models in all performance indicators and visual effects. The constructed model had a much shorter detection time than the Faster R-CNN model (only one third of that of the latter), thus meeting the requirements of real-time detection.

CONCLUSION

The proposed carotid artery plaque detection method has good performance for accurate identification of carotid plaques in ultrasound images.

[Construction of an evaluation index system for the capability of comprehensive control of mountain - type zoonotic visceral leishmaniasis based on the One Health concept]

OBJECTIVE

To construct an evaluation index system for the capability of comprehensive control of mountain-type zoonotic visceral leishmaniasis based on the One Health concept, so as to provide insights into the control and elimination of mountain-type zoonotic visceral leishmaniasis using the One Health approach.

METHODS

A preliminary evaluation index system was constructed based on literature review, panel discussions and field surveys. Thirty-three experts were selected from 7 provincial disease control and prevention centers in Beijing Municipality, Hebei Province, Shanxi Province, Henan Province, Sichuan Province, Shaanxi Province and Gansu Province where mountain-type zoonotic visceral leishmaniasis was endemic, and two rounds of expert consultations were conducted to screen the indicators. The positive coefficient, degree of concentration, degree of coordination, and authority of the experts were calculated, and the normalized weights of each index were calculated with the analytic hierarchy process.

RESULTS

The response rates of questionnaires during two rounds of expert consultation were both 100.00% (33/33), and the authority coefficients of the experts were 0.86 and 0.88, respectively. The coefficients of coordination among experts on the rationality, importance, and operability of the indicators were 0.392, 0.437, 0.258, and 0.364, 0.335, 0.263, respectively (all P values < 0.05). Following screening, the final evaluation index system included 3 primary indicators, 17 secondary indicators, and 50 tertiary indicators. The normalized weights of primary indicators "external environment", "internal support" and "comprehensive control" were 16.98%, 38.73% and 44.29%, respectively. Among the secondary indicators of the primary indicator "external environment", the highest weight was seen for natural environment (66.67%), and among the secondary indicators of the primary indicator "internal support", the lowest weight was seen for the scientific research for visceral leishmaniasis control (8.26%), while other indicators had weights of 12.42% to 13.38%. Among the secondary indicators of the primary indicator "comprehensive control", the weight was 16.67% for each indicator.

CONCLUSIONS

An evaluation index system has been constructed for the capability of comprehensive control of mountain-type zoonotic visceral leishmaniasis based on the One Health concept. In addition to assessment of the effect of conventional mountain-type zoonotic visceral leishmaniasis control measures, this index system integrates the importance of top-level design, organizational management, and implementation of control measures, and includes indicators related to multi-sectoral cooperation.

Genome-wide association study identifies multiple loci influencing duck serum biochemical indicators in the laying period

1. Laying performance is an important economic trait in poultry. The blood is essential in transporting nutrients to the yolk and albumen and is necessary for egg formation.2. This study calculated the phenotypic relationships of duck egg quality, egg production efficiency and 22 serum parameters in the egg-laying stage. Using a variety of methodologies, a genome-wide association study (GWAS) was carried out to uncover the genetic foundations of the 22 serum biochemical markers of laying ducks.3. Spearman correlation coefficients between the egg production (226-329 per day) and the serum parameters were all weak, being less than 0.3. This analysis was done on 22 serum parameters, with total protein (TP), total triglycerides (TG), calcium (Ca) and phosphorous (P) having the highest correlation coefficients (r = 0.56-0.88). The coefficients for blood markers, such as total cholesterol (CHOL), total bilirubin (TBIL), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) varied from 0.70-0.94.4. Based on single-marker single-trait genome-wide analyses by a mixed linear model program of EMMAX, nine candidate genes were associated with enzyme traits (AST/ALT aspartate transaminase/glutamic-pyruvic transaminase, creatine kinase) and 19 candidate genes were associated with metabolism and protein-related serum parameters (glucose, total bile acid, uric acid (UA), albumin (ALB).5. The mvLMM (multivariate linear mixed model) of GEMMA software was used to carry out multiple trait integrated GWAS. Two candidate genes were found in the TP-TG-CA-P analysis and seven candidate genes in the CHOL_LDL-C_HDL-C_TBIL study. There was a high genetic correlation between the two groups.

An archaeal nitrile hydratase from the halophilic archaeon A07HB70 exhibits high tolerance to 3-cyanopyridine and nicotinamide

Nitrile hydratase (NHase, EC 4.2.1.84) is widely used in the industrial production of biosynthetic amide compounds. NHases obtained from prokaryotic and eukaryotic sources have been widely studied, while the NHases derived from archaeal sources have not been reported. Here, we focused on a distinctive NHase derived from a halophilic archaeon (archaeon A07HB70, A.r NHase) that thrives in high-salt environments. A notable feature of this enzyme is the natural fusion of the α subunit with the activator. A.r NHase retained 89.14 % of its activity after exposure to 4.0 M substrate and 97.52 % of its activity after exposure to 4.0 M product. These findings indicate that A.r NHase exhibits significantly higher tolerance to both substrate and product compared to NHases derived from other sources, which may be due to its unique genetic structure. The investigation of such highly stable archaeal NHase can offer a theoretical foundation for modifying NHase derived from other sources. This, in turn, would enhance the potential industrial application of NHase.

Vegetation-fire feedbacks increase subtropical wildfire risk in scrubland and reduce it in forests

Climate dictates wildfire activity around the world. But East and Southeast Asia are an apparent exception as fire-activity variation there is unrelated to climatic variables. In subtropical China, fire activity decreased by 80% between 2003 and 2020 amid increased fire risks globally. Here, we assessed the fire regime, vegetation structure, fuel flammability and their interactions across subtropical Hubei, China. We show that tree basal area (TBA) and fuel flammability explained 60% of fire-frequency variance. Fire frequency and fuel flammability, in turn, explained 90% of TBA variance. These results reveal a novel system of scrubland-forest stabilized by vegetation-fire feedbacks. Frequent fires promote the persistence of derelict scrubland through positive vegetation-fire feedbacks; in forest, vegetation-fire feedbacks are negative and suppress fire. Thus, we attribute the decrease in wildfire activity to reforestation programs that concurrently increase forest coverage and foster negative vegetation-fire feedbacks that suppress wildfire.

Graphene oxide-enhanced colorimetric detection of Mec A gene based on toehold-mediated strand displacement

Mec A, as a representative gene mediating resistance to β-lactam antibiotics in methicillin-resistant Staphylococcus aureus (MRSA), allows a new genetic analysis for the detection of MRSA. Here, a sensitive, prompt, and visual colorimetry is reported to detect the Mec A gene based on toehold-mediated strand displacement (TMSD) and the enrichment effect of graphene oxide (GO). The Mec A triggers to generate the profuse amount of signal units of single-stranded DNA (SG) composed of a long single-stranded base tail and a base head: the tail can be adsorbed and enriched on the surface of GO; the head can form a G quadruplex structure to exert catalytic function towards 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid). Therefore, through the enrichment effect of GO, the signal units SG reflects different degrees of signal amplification on different substrates (such as aqueous solution or filter membrane). This strategy demonstrates a broad linear working range from 100 pM to 1.5 nM (solution) and 1 pM to 1 nM (filter membrane), with a low detection limit of 39.53 pM (solution) and 333 fM (filter membrane). Analytical performance in real samples suggests that this developed colorimetry is endowed with immense potential for clinical detection applications.

Structure-oriented engineering of nitrile hydratase: Reshaping of substrate access tunnel and binding pocket for efficient synthesis of cinnamamide

Cinnamamide and its derivatives are the most common and important building blocks widely present in natural products. Currently, nitrile hydratase (NHase, EC 4.2.1.84) has been widely used in large-scale industrial production of nicotinamide and acrylamide, while its catalytic activity is extremely low or inactive for bulky nitrile substrates such as cinnamonitrile. Therefore, beneficial variant βF37P/L48P/F51N were obtained from PtNHase of Pseudonocardia thermophila JCM3095 by reshaping of substrate access tunnel and binding pocket, which exhibited 14.88-fold improved catalytic efficiency compared to the wild-type PtNHase. Structure analysis, molecular dynamics simulations and dynamical cross-correlation matrix (DCCM) analysis revealed that the introduced mutations enlarged the substrate access tunnel and binding pocket, enhanced overall anti-correlated movements of enzymes, which would promote product release during the dynamic process of catalysis. In a hydration process, the complete conversion of 5 mM cinnamonitrile was achieved by βF37P/L48P/F51N in a 50 mL reaction, with cinnamamide yield of almost 100 % and productivity of 0.736 g L-1 h-1. The study demonstrates the co-evolution of substrate access tunnel and binding pocket is an effective strategy, and provides a valuable reference for future research. Furthermore, NHases have huge potential for catalyzing bulky nitriles to form corresponding amides in large-scale industrial production.

Metabolic engineering of glycolysis in Escherichia coli for efficient production of patchoulol and τ-cadinol

Glucose metabolism suppresses the microbial synthesis of sesquiterpenes with a syndrome of "too much of a good thing can be bad". Here, patchoulol production in Escherichia coli was increased 2.02 times by engineering patchoulol synthase to obtain an initial strain. Knocking out the synthetic pathway for cyclic adenosine monophosphate relieved glucose repression and improved patchoulol titer and yield by 27.7 % and 43.1 %, respectively. A glycolysis regulation device mediated by pyruvate sensing was constructed which effectively alleviated overflow metabolism in a high-glucose environment with 10.2 % greater patchoulol titer in strain 070QA. Without fine-tuning the glucose-feeding rate, patchoulol titer further increased to 1675.1 mg/L in a 5-L bioreactor experiment, which was the highest level reported in E. coli. Using strain 070QA as a chassis, the τ-cadinol titer reached 15.2 g/L, representing the first report for microbial production of τ-cadinol. These findings will aid in the industrial production of sesquiterpene.

Genomic characterization of Salmonella isolated from retail chicken and humans with diarrhea in Qingdao, China

Salmonella, especially antimicrobial resistant strains, remains one of the leading causes of foodborne bacterial disease. Retail chicken is a major source of human salmonellosis. Here, we investigated the prevalence, antimicrobial resistance (AMR), and genomic characteristics of Salmonella in 88 out of 360 (24.4%) chilled chicken carcasses, together with 86 Salmonella from humans with diarrhea in Qingdao, China in 2020. The most common serotypes were Enteritidis and Typhimurium (including the serotype I 4,[5],12:i:-) among Salmonella from both chicken and humans. The sequence types were consistent with serotypes, with ST11, ST34 and ST19 the most dominantly identified. Resistance to nalidixic acid, ampicillin, tetracycline and chloramphenicol were the top four detected in Salmonella from both chicken and human sources. High multi-drug resistance (MDR) and resistance to third-generation cephalosporins resistance were found in Salmonella from chicken (53.4%) and humans (75.6%). In total, 149 of 174 (85.6%) Salmonella isolates could be categorized into 60 known SNP clusters, with 8 SNP clusters detected in both sources. Furthermore, high prevalence of plasmid replicons and prophages were observed among the studied isolates. A total of 79 antimicrobial resistant genes (ARGs) were found, with aac(6')-Iaa, blaTEM-1B, tet(A), aph(6)-Id, aph(3″)-Ib, sul2, floR and qnrS1 being the dominant ARGs. Moreover, nine CTX-M-type ESBL genes and the genes blaNMD-1, mcr-1.1, and mcr-9.1 were detected. The high incidence of MDR Salmonella, especially possessing lots of mobile genetic elements (MGEs) in this study posed a severe risk to food safety and public health, highlighting the importance of improving food hygiene measures to reduce the contamination and transmission of this bacterium. Overall, it is essential to continue monitoring the Salmonella serotypes, implement the necessary prevention and strategic control plans, and conduct an epidemiological surveillance system based on whole-genome sequencing.

Creation of Architecturally Minimal Transcriptionally Activating Riboswitches Responsive to Theophylline Reveals an Unconventional Design Strategy

Riboswitches are noncoding RNA switches that are largely utilized in bacteria and play a significant role in synthetic biology. Nonetheless, their natural counterparts possess lengthy sequences and intricate structures, posing challenges for their modular integration into complex gene circuits. Consequently, it is imperative to develop simplified synthetic riboswitches that can be effortlessly incorporated into gene circuits. The conventional approach to generate synthetic riboswitches entails tedious library construction and extensive screening, which frequently yields suboptimal performance. To overcome this obstacle, alternative methods are urgently needed. In this study, we created a novel approach to designing a diverse set of transcription-activating riboswitches that exhibit high performance and broad compatibility. The strategy involved starting with a synthetic theophylline RNA aptamer and designing an expression platform that forms a transcriptional terminator in its inactive state but switches to an antiterminator when it is activated. Several sequences were designed, constructed, and subjected to virtual screening, resulting in the identification of two transcription-activating riboswitches. These riboswitches were then engineered to reduce the basal leakage and increase the activation level through extending the hairpin region using a screened random sequence. These architecturally minimal synthetic riboswitches were highly adapted to different constitutive promoters in a modular manner, generating a differentially responsive output to theophylline. As a proof-of-principle, the synthetic riboswitches were applied to rewire a synthetic quorum-sensing circuit (QSC). The reprogrammed QSC successfully modulated the temporal responsive profile against the activation. This strategy is expected to expand the variety of high-performance riboswitches that are responsive to different ligands, thereby further facilitating the design of complex genetic circuits.

Discovery and Engineering of a Novel Bacterial L-Aspartate α-Decarboxylase for Efficient Bioconversion

L-aspartate α-decarboxylase (ADC) is a pyruvoyl-dependent decarboxylase that catalyzes the conversion of L-aspartate to β-alanine in the pantothenate pathway. The enzyme has been extensively used in the biosynthesis of β-alanine and D-pantothenic acid. However, the broad application of ADCs is hindered by low specific activity. To address this issue, we explored 412 sequences and discovered a novel ADC from Corynebacterium jeikeium (CjADC). CjADC exhibited specific activity of 10.7 U/mg and Km of 3.6 mM, which were better than the commonly used ADC from Bacillus subtilis. CjADC was then engineered leveraging structure-guided evolution and generated a mutant, C26V/I88M/Y90F/R3V. The specific activity of the mutant is 28.8 U/mg, which is the highest among the unknown ADCs. Furthermore, the mutant displayed lower Km than the wild-type enzyme. Moreover, we revealed that the introduced mutations increased the structural stability of the mutant by promoting the frequency of hydrogen-bond formation and creating a more hydrophobic region around the active center, thereby facilitating the binding of L-aspartate to the active center and stabilizing the substrate orientation. Finally, the whole-cell bioconversion showed that C26V/I88M/Y90F/R3V completely transformed 1-molar L-aspartate in 12 h and produced 88.6 g/L β-alanine. Our study not only identified a high-performance ADC but also established a research framework for rapidly screening novel enzymes using a protein database.

Synergetic engineering of Escherichia coli for efficient production of l-tyrosine

l-Tyrosine, an aromatic non-essential amino acid, is the raw material for many important chemical products, including levodopa, resveratrol, and hydroxytyrosol. It is widely used in the food, drug, and chemical industries. There are many studies on the synthesis of l-tyrosine by microorganisms, however, the low titer of l-tyrosine limited the industrial large-scale production. In order to enhance l-tyrosine production in Escherichia coli, the expression of key enzymes in the shikimate pathway was up- or down-regulated. The l-tyrosine transport system and the acetic acid biosynthesis pathway were modified to further enhance l-tyrosine production. In addition, the phosphoketolase pathway was introduced in combination with cofactor engineering to redirect carbon flux to the shikimate pathway. Finally, after adaptive laboratory evolution to low pH an optimal strain was obtained. The strain can produce 92.5 g/L of l-tyrosine in a 5-L fermenter in 62 h, with a yield of 0.266 g/g glucose.

Distributed genotyping and clustering of Neisseria strains reveal continual emergence of epidemic meningococcus over a century

Core genome multilocus sequence typing (cgMLST) is commonly used to classify bacterial strains into different types, for taxonomical and epidemiological applications. However, cgMLST schemes require central databases for the nomenclature of new alleles and sequence types, which must be synchronized worldwide and involve increasingly intensive calculation and storage demands. Here, we describe a distributed cgMLST (dcgMLST) scheme that does not require a central database of allelic sequences and apply it to study evolutionary patterns of epidemic and endemic strains of the genus Neisseria. We classify 69,994 worldwide Neisseria strains into multi-level clusters that assign species, lineages, and local disease outbreaks. We divide Neisseria meningitidis into 168 endemic lineages and three epidemic lineages responsible for at least 9 epidemics in the past century. According to our analyses, the epidemic and endemic lineages experienced very different population dynamics in the past 100 years. Epidemic lineages repetitively emerged from endemic lineages, disseminated worldwide, and apparently disappeared rapidly afterward. We propose a stepwise model for the evolutionary trajectory of epidemic lineages in Neisseria, and expect that the development of similar dcgMLST schemes will facilitate epidemiological studies of other bacterial pathogens.

Bacterial indole-3-lactic acid affects epithelium-macrophage crosstalk to regulate intestinal homeostasis

Tryptophan and its derivatives perform a variety of biological functions; however, the role and specific mechanism of many tryptophan derivatives in intestinal inflammation remain largely unclear. Here, we identified that an Escherichia coli strain (Ec-TMU) isolated from the feces of tinidazole-treated individuals, and indole-3-lactic acid (ILA) in its supernatant, decreased the susceptibility of mice to dextran sulfate sodium-induced colitis. Ec-TMU and ILA contribute to the relief of colitis by inhibiting the production of epithelial CCL2/7, thereby reducing the accumulation of inflammatory macrophages in vitro and in vivo. Mechanistically, ILA downregulates glycolysis, NF-κB, and HIF signaling pathways via the aryl hydrocarbon receptor, resulting in decreased CCL2/7 production in epithelial cells. Clinical evidence suggests that the fecal ILA level is negatively correlated with the progression indicator of inflammatory bowel diseases. These results demonstrate that ILA has the potential to regulate intestinal homeostasis by modulating epithelium-macrophage interactions.

Discriminating minimal residual disease status in multiple myeloma based on MRI: utility of radiomics and comparison of machine-learning methods

AIM

To explore the possibility of discriminating minimal residual disease (MRD) status in multiple myeloma (MM) based on magnetic resonance imaging (MRI) and identify optimal machine-learning methods to optimise the clinical treatment regimen.

MATERIALS AND METHODS

A total of 83 patients were analysed retrospectively. They were divided randomly into training and validation cohorts. The regions of interest were segmented and radiomics features were extracted and analysed on two sequences, including T1-weighted imaging (WI) and fat saturated (FS)-T2WI, and then radiomics models were built in the training cohort and evaluated in the validation cohort. Clinical characteristics were calculated to build a traditional model. A combined model was also built using the clinical characteristics and radiomics features. Classification accuracy was assessed using area under the curve (AUC) and F1 score.

RESULTS

In the training cohort, only the bone marrow (BM) infiltrate ratio (p=0.005) was retained after univariate and multivariable logistic regression analysis. In T1WI, the linear support vector machine (SVM) achieved the best performance compared to other classifiers, with AUCs of 0.811 and 0.708 and F1 scores of 0.792 and 0.696 in the training and validation cohorts, respectively. Similarly, in FS-T2WI sequence, linear SVM achieved the best performance with AUCs of 0.833 and 0.800 and F1 score of 0.833 and 0.800. The combined model constructed by the FS-T2WI-linear SVM and BM infiltrate ratio outperformed the traditional model (p=0.050 and 0.012, Delong test), but showed no significant difference compared with the radiomics model (p=0.798 and 0.855).

CONCLUSION

The linear SVM-based machine-learning method can offer a non-invasive tool for discriminating MRD status in MM.

Stepwise genetic modification for efficient expression of heterologous proteins in Aspergillus nidulans

Filamentous fungi are widely used in food fermentation and therapeutic protein production due to their prominent protein secretion and post-translational modification system. Aspergillus nidulans is an important model strain of filamentous fungi, but not a fully developed cell factory for heterologous protein expression. One of the limitations is its relatively low capacity of protein secretion. To alleviate this limitation, in this study, the protein secretory pathway and mycelium morphology were stepwise modified. With eGFP as a reporter protein, protein secretion was significantly enhanced through reducing the degradation of heterologous proteins by endoplasmic reticulum-associated protein degradation (ERAD) and vacuoles in the secretory pathway. Elimination of mycelial aggregation resulted in a 1.5-fold and 1.3-fold increase in secretory expression of eGFP in typical constitutive and inducible expression systems, respectively. Combined with these modifications, high secretory expression of human interleukin-6 (HuIL-6) was achieved. Consequently, a higher yield of secretory HuIL-6 was realized by further disruption of extracellular proteases. Overall, a superior chassis cell of A. nidulans suitable for efficient secretory expression of heterologous proteins was successfully obtained, providing a promising platform for biosynthesis using filamentous fungi as hosts. KEY POINTS: • Elimination of mycelial aggregation and decreasing the degradation of heterologous protein are effective strategies for improving the heterologous protein expression. • The work provides a high-performance chassis host △agsB-derA for heterologous protein secretory expression. • Human interleukin-6 (HuIL-6) was expressed efficiently in the high-performance chassis host △agsB-derA.

The metagenomic and metabolomic profile of the gut microbes in Chinese full-term and late preterm infants treated with Clostridium butyricum

The present study investigated the composition, abundance, and diversity of gut microbes in full-term and late-preterm infants from a medical center in eastern China. A total of 144 genomes of stool samples were captured for 16S rRNA metagenomic analyses. A high abundance of commensal intestinal bacteria was detected in these samples such as Phocaeicola vulgatus, Escherichia coli, and Faecalibacterium prausnitzii, indicating a relatively consistent diversity of gut microbes in the present full-term infants aged 38-40 weeks. However, late preterm infants (n = 50) with mandatory antimicrobials feeding exhibited lower diversity but a higher composition of opportunistic pathogens such as Enterococcus species. Centralized on the situation, we explored the regulatory effect of Clostridium butyricum as probiotics on these late preterm infants. The consumption of C. butyricum did not restore the composition of gut microbes altered by antimicrobials to normal levels, although several opportunistic pathogens decreased significantly after probiotic therapy including Staphylococcus aureus, Sphingomonas echinoides, and Pseudomonas putida. We also compared the effects of day-fed versus night-fed probiotics. Intriguingly, the nighttime feeding showed a higher proportion of C. butyricum compared with probiotic day-feeding. Finally, fecal metabolome and metabolites were analyzed in late preterm infants with (n = 20) or without probiotic therapy (n = 20). The KEGG enrichment analysis demonstrated that vitamin digestion and absorption, synaptic vesicle cycle, and biotin metabolism were significantly increased in the probiotic-treated group, while MSEA indicated that a series of metabolism were significantly enriched in probiotic-treated infants including glycerolipid, biotin, and lysine, indicating the complex effects of probiotic therapy on glutathione metabolism and nutrients digestion and absorption in late preterm infants. Overall, this study provided metagenomic and metabolomic profile of the gut microbes in full-term newborns and late preterm infants in eastern China. Further studies are needed to support and elucidate the role of probiotic feeding in late preterm infants with mandatory antimicrobial treatment.

Efficacy of Postoperative Radiotherapy for Patients with New N2 Descriptors of Subclassification in Completely Resected Non-Small Cell Lung Cancer: A Real-World Study

PURPOSE/OBJECTIVE(S)

Patients with N2 non-small cell lung cancer (NSCLC) were heterogeneous groups and required further stratification. The International Society for the Study of Lung Cancer (IASLC) added new descriptors of three sub-stages for stage N2 NSCLC: N2 at a single station without N1 involvement (N2a1), N2 at a single station with N1 involvement (N2a2), and N2 at multiple stations (N2b). This study aimed to investigate the efficacy of postoperative radiotherapy (PORT) for patients with these N2 descriptors.

MATERIALS/METHODS

Patients with histologically confirmed NSCLC after complete resection and divided into PORT group and non-PORT group. The primary endpoint was DFS. The second endpoints were overall survival (OS) and locoregional recurrence-free survival (LRFS). Propensity-score matching (PSM) of baseline characteristics between the PORT and non-PORT groups was used for validation.

RESULTS

Totally 1832 patients were enrolled, including 308 N2a1 patients, 682 N2a2 patients, and 842 N2b patients. The median follow-up time was 50.1 months. The survival outcomes of the PORT and non-PORT groups before PSM were shown in Table 1. For patients with N2a1, PORT could not improve the DFS (median DFS of the PORT group and the non-PORT group: not reached vs. 46.8 months, P = 0.41), OS (P = 0.85), or LRFS (P = 0.32), which were consistent with the multivariate analysis and data after the PSM. For patients with N2a2, PORT significantly improved the DFS (median DFS 29.7 vs. 22.2 months, P = 0.02), OS (P = 0.03), and LRFS (P = 0.01). The multivariate analysis and data after the PSM confirmed the benefits in DFS and LRFS, but no benefit was observed in OS (multivariate analysis: HR 0.79, P = 0.18; median OS after PSM: 103.7 vs. 63.1 months, P = 0.34). For patients with N2b, PORT could not improve the DFS (median DFS 20.6 vs. 21.2 months, P = 0.39) but significantly improved the OS (P<0.001) and LRFS (P<0.001). However, the multivariate analysis showed that PORT significantly improved DFS (HR 0.81, P = 0.03), consistent with the data after the PSM (median DFS 20.6 and 17.6 months, P = 0.04).

CONCLUSION

PORT significantly improved the DFS and LRFS in patients with N2a2 and significantly improved the DFS, LRFS, and OS in patients with N2b. Patients with N2a1 could not benefit from PORT.

Radiation Induced Lung Injury in Rats after Pre-Oxygenation Radiotherapy

PURPOSE/OBJECTIVE(S)

Deep inspiratory breath holding (DIBH) has been widely used during the radiotherapy of thoracic tumors. The main disadvantage of voluntary DIBH is the short duration of each breath hold. The hypocapnia induced by hyperoxia (oxygen concentration > 50%) pre-oxygenation (PreO2) combined with mechanical hyperventilation has been reported to prolong the duration of single breath hold, but its safety remains controversial, especially the sensitivity of lung tissue to radiation damage under hyperoxia exposure has not been elucidated. In this study, we aim to investigate the changes of radiation induced lung injury in rats after PreO2 radiation.

MATERIALS/METHODS

We evaluated the lung tissue of rats at different time points (48h, 2w, 4w, 8w, 12w) after thoracic radiation (15Gy single fraction to the right lung), and sequenced the transcriptome of lung tissue at 48 hours after irradiation. Rat cohorts (n = 7/group): 1. Control (Con); 2. Radiation group (RT); 3. Pre-oxygenation (oxygen concentration > 90%) for 8 hours before thoracic radiation (PreO2).

RESULTS

The inflammatory exudation emerged in the pulmonary interstitium at 48 hours, and reached the most serious alveolitis after four weeks of irradiation (the comparison of alveolitis scores in RT4w vs Con4w and PreO2(4w) vs Con4w, P<0.001) on hematoxylin-eosin staining. While the alveolitis scores in RT group and PreO2 group were not statistically different at each time point. Masson staining showed that the pulmonary fibrosis in the RT group and the PreO2 group reached an obvious pathological change at 12 weeks after irradiation, but the difference between the two groups was not significant. Transcriptome sequencing showed that the number of differential genes in PreO2 vs Con was 559 (302 up-regulated genes and 257 down-regulated genes). The GO enrichment analysis indicated that chromosome segregation was the most significant functional item with P value in the comparative analysis, and the KEGG enrichment analysis suggested that cell division was the most significant enrichment pathway of these differential genes. While there was a small quantity of differential genes in PreO2 vs RT group (3 up-regulated genes and 12 down-regulated genes). Pentose and glucuronate conversions were the most significant enrichment pathway of these differential genes.

CONCLUSION

This study demonstrated that PreO2 radiotherapy did not increase the severity of radiation induced lung injury in rats compared to conventional radiotherapy. Further study should be conducted to confirm these results and to investigate the regulatory mechanism of pneumonia caused by PreO2 radiotherapy.

Inter-fraction Dynamics during Adaptive Hypofractionated Radiotherapy for Brain Metastases with a MR LINAC

PURPOSE/OBJECTIVE(S)

This study examined the displacement and deformation in brain metastases (BMs) during adaptive hypofractionated radiotherapy (HFRT) on a magnetic resonance imaging linear accelerator (MR LINAC). In addition, the contouring variability between enhanced T1 (T1+c) and T2/FLAIR (T2f) sequence to define gross tumor volume (GTV) was compared.

MATERIALS/METHODS

Patients with 1-3 BMs and treated with MR LINAC were enrolled. T1+c sequence was acquired at initial planning, while T2/T2f was acquired during each fraction. GTV at initial planning (GTVi) and fraction 1-n (GTV1-n) were contoured in all images. Dice similarity coefficient (DSC) was used to quantify the contouring variability between different sequences at initial planning. The three-dimensional coordinate values of geometric centers of GTVi and GTV1-n were recorded and the distance was calculated. Statistical analysis was performed using two-sided paired t-test.

RESULTS

Between December 2019 and October 2022, 19 patients with 22 BMs were analyzed. The median age was 64 y (37-84 y) and the major primary tumor was lung cancer (89.5%). The median dose was 52 Gy in 13 fractions (30 Gy/5f- 60 Gy/20 f). The median GTVi on T1c, T2f and T2 sequences were 6.70cc (0.41-84.85 cc), 6.70 cc (0.35-84.14 cc, p = 0.924) and 6.16 cc (0.32-79.44 cc, p = 0.117), respectively. The mean DSC was 0.95 (0.76-1.00) and 0.86 (0.64-0.97) when comparing GTVi on T1c/T2f and T1c/T2, respectively. All of the lesions achieved volume reduction during HFRT and the mean reduction rate was 28.8% (4.8%-71.0%) at the end of HFRT. 54.5% of the BMs were reduced by more than 20%. The median treatment course and BED to get 20% reduction was 2/3 (40%-93%) and 40.8 Gy (24.5-67.5 Gy), respectively. The median shift of center of GTV1-n was 0.8 mm (0-2.5mm). The center of 7 lesions (31.8%) deviated more than 1mm from GTVi.

CONCLUSION

GTV contouring variability was seen between T1c, T2f and T2 sequences. The coincidence of T1+c and T2f was better than T1+c and T2 in BMs. Since reductions in volume and changes of lesion center was observed during HFRT, the use of MR-guided radiation therapy (RT) and treatment adaptation is needed. The optimal timing for treatment plan modification might be when the course of treatment reaches 2/3 for most large BMs. Further research to find out patients who may benefit form MR-guided adaptive RT is ongoing.

Resource allocation of rural institutional elderly care in China's new era: spatial-temporal differences and adaptation development

OBJECTIVES

In the new era of China, to ensure that rural residents can get the corresponding institutional elderly services equally, it is necessary to investigate the current situation of resource allocation of rural institutional elderly care and make corresponding adaptation suggestions.

STUDY DESIGN

This research discusses the characteristics and evolution pattern of rural aging, the resource allocation of rural elderly care institutions, and the adaptation degree of rural institutional elderly care resource and aging.

METHODS

The research methodology consists of the following stages: entropy-based Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS), kernel density estimation, coupling coordination, spatial autocorrelation, and Theil index decomposition.

RESULTS

The degree of aging in rural areas of China is rising, and the whole population has entered a moderate aging society, showing the spatial characteristics of 'high in the east and low in the west'. The resource allocation of rural institutional elderly care in China is at a low level, and the absolute differences among provinces tend to reduce over time, and the overall resource allocation level tends to decline. The provinces that were in the mismatched adaptation relationship in the early stage have improved; however, the number of provinces with mismatched adaptability has continued to increase. The local spatial autocorrelation of resource adaptation verifies that the middle and lower reaches of the Yangtze River as the core form a hot spot, and during the observation period, the spatial agglomeration effect of the core is strengthened. The Theil index decomposition of resource adaptation indicates that the within-group differences between the eastern and western regions is significantly higher than that between the northeastern and central regions.

CONCLUSIONS

First, special attention should be paid to preventing the resource allocation of rural institutional elderly care in the eastern and western regions from falling again. Second, to avoid more and more low-adapted provinces falling into the 'mismatch dilemma' with the deepening of the aging degree. Third, strengthen cooperation among regions and promote the coordinated development of resource allocation of institutional elderly care in various regions. Fourth, the priority of institutional elderly care balanced development should be given to the eastern region and western region, thus weakening the overall difference.

Chemoradiotherapy Combined with Nab-Paclitaxel plus Cisplatin in Patients with Locally Advanced Borderline Resectable or Unresectable Esophageal Squamous Cell Carcinoma: A Phase I/II Study

PURPOSE/OBJECTIVE(S)

To evaluate the efficacy and safety of nanoparticle albumin-bound paclitaxel (nab-PTX) plus cisplatin as the regimen of conversional chemoradiotherapy (cCRT) in locally advanced borderline resectable or unresectable esophageal squamous cell carcinoma (ESCC).

MATERIALS/METHODS

Patients with locally advanced ESCC (cT3-4, Nany, M0-1, M1 was limited to lymph node metastasis in the supraclavicular area) were enrolled. All the patients received the cCRT of nab-PTX plus cisplatin. After the cCRT, those resectable patients received esophagectomy; those unresectable patients continued to receive the definitive chemoradiotherapy (dCRT). The locoregional control (LRC), overall survival (OS), progression-free survival (PFS), distant metastasis free survival (DMFS), pathological complete response (pCR), R0 resection rate and adverse events (AEs) were calculated.

RESULTS

A total of 45 patients with ESCC treated from October 2019 to May 2021 were finally included. The median follow-up time was 30.3 months. The LRC, OS, EFS, DMFS at 1and 2 years were 81.5%, 86.6%, 64.3%, 73.2% and 72.4%, 68.8%, 44.8%, 52.7% respectively. 21 patients (46.7%) received conversional chemoradiotherapy plus surgery (cCRT+S). The pCR rate and R0 resection rate were 47.6% and 84.0%. The LRC rate at 1 and 2 years were 95.0%, 87.1% in cCRT+S patients and 69.3%, 58.7% in dCRT patients respectively (HR, 5.14; 95% CI, 1.10-23.94; P = 0.021). The OS rate at 1 and 2 years were 95.2% and 84.2% in resectable patients compared to 78.8% and 54.4% in unresectable patients (HR, 3.41; 95% CI, 1.10-10.61; P = 0.024). The toxicities during chemoradiotherapy were tolerated, the most common grade 3-4 toxicities were radiation esophagitis (15.6%).

CONCLUSION

Nab-PTX plus cisplatin were effective and safe as the regimen of conversional chemoradiotherapy of ESCC. The patients receiving conversional chemoradiotherapy plus surgery (cCRT+S) were prone to have a better survival.

Clinical Outcomes with Thoracic Radiotherapy for Extensive-Stage Small-Cell Lung Cancer in the Era of Immunotherapy: A Retrospective Analysis

PURPOSE/OBJECTIVE(S)

Chemo-immunotherapy has shown significant benefits for extensive-stage small-cell lung cancer (ES-SCLC), which prolonged overall survival (OS) of nearly 2-4.5 months compared with platinum-based chemotherapy alone. However, thoracic radiotherapy (TRT), was not allowed to be used in previous trials. This retrospective study aimed to evaluate the safety and efficiency of TRT for ES-SCLC patients in the era of Immunotherapy.

MATERIALS/METHODS

We retrospectively reviewed ES-SCLC patients treated with chemo-immunotherapy between 2017 and 2021 in our center. Patients who accepted consolidative or salvage TRT were included. The overall survival, progression-free survival (PFS), local progression-free survival (LPFS), and distant progression free-survival (DPFS) were calculated using the Kaplan-Meier method. Toxicity was recorded based on CTCAE 5.0 scale.

RESULTS

We finally enrolled 30 patients in our study. The median follow-up time was 26.0 months (95% confidence interval, 18.2-33.8 months). 26(86.7%) patients have undergone first-line chemotherapy and immunotherapy, while 4(13.3%) have undergone immunotherapy as a second-line agent. 23(76.6%) patients achieved CR/PR/SD to initial systematic therapy. All patients were treated with TRT with a median dose of 51 Gy (24-60.2 Gy). The median interval between TRT and immunotherapy was 35 days. Median OS was 26 months (95% confidence interval, 17.8-34.2 months) and median PFS was 8 months (95% confidence interval, 5.3-10.7 months). 2-year OS, PFS, and DPFS were 51.4%, 21.4%, and 27.4%, respectively. 18 months LPFS was 59.6%. There was no ≥ G3 radiation-related adverse event except 2(6.7%) G3 esophagitis. G1-2 pneumonitis was reported in 8(26.7%) patients.

CONCLUSION

TRT is well-tolerated and effective for selected ES-SCLC patients in the modern era of immunotherapy. Prospective trials are still needed to further evaluate the combination of TRT and immunotherapy for patients with ES-SCLC.

The KRAS-Variant and Cetuximab in HPV-Positive Oropharyngeal Cancer in NRG/RTOG 1016

PURPOSE/OBJECTIVE(S)

NRG/RTOG 1016 was a non-inferiority phase III trial comparing radiation with cisplatin versus cetuximab monotherapy for patients with HPV-positive oropharyngeal squamous cell carcinoma (SCC). The trial did not meet the non-inferiority criteria for overall survival (OS) and had significantly worse progression-free survival (PFS) and locoregional failure (LRF) in patients treated with cetuximab. Based on prior evidence that HNSCC patients with a germ-line mutation in KRAS (the KRAS-variant) had a positive response to radiation with cisplatin plus cetuximab without increased toxicity, samples from RTOG 1016 were used to test the protocol-specified hypothesis that KRAS-variant patients will have better outcomes when receiving IMRT + cetuximab monotherapy compared to IMRT + cisplatin.

MATERIALS/METHODS

The KRAS-variant was tested in 562 samples at MiraDx, a CLIA-certified laboratory. OS, PFS, LRF, and distant metastases (DM) were as defined per the RTOG 1016 protocol, and hazard ratios (HRs) were estimated by (cause-specific) Cox models. Negative binomial regression was used to model the number of treatment-related acute and late (≤ and > 180 days from end of treatment, respectively) grade 3-5 adverse events. To assess the predictive role of the KRAS-variant, all models included KRAS, assigned treatment, and their interaction, with the interaction tested at two-sided 0.05. HRs and toxicity ratios are expressed as IMRT + cetuximab / IMRT + cisplatin.

RESULTS

The prevalence of the KRAS-variant was 16% with similar patient and tumor characteristics and well-balanced treatment arms for variant and non-variant patients. Median follow-up was 8.6 years. There was no significant interaction between KRAS and treatment for OS (p = 0.99), PFS (p = 0.56), LRF (p = 0.09), or DM (p = 0.19) (Table 1). In KRAS-variant patients the mean acute and late toxicity ratios were 0.53 (95% CI 0.36, 0.80) and 1.62 (95% CI 0.57, 4.62). In non-variant patients, the mean acute and late toxicity ratios were 0.80 (95% CI 0.67, 0.95) and 0.55 (95% CI 0.35, 0.87), respectively. The interaction of KRAS and treatment was not significant for acute (p = 0.07) or late toxicity (p = 0.07).

CONCLUSION

While this study does not directly refute prior evidence that KRAS-variant patients benefit from radiation + cisplatin and cetuximab, this study does not support the hypothesis that the KRAS-variant is a predictive biomarker of improved outcome in HPV+ oropharyngeal SCC patients treated with IMRT + cetuximab alone, and suggests that for KRAS-variant patients, potential benefits in LRF and acute toxicity with cetuximab may be offset by worse DM and worse late toxicity.

Retrospective study of preservation and transection of the round ligament of uterus during laparoscopic transabdominal preperitoneal inguinal hernia repair in adult women

PURPOSE

The processing of the round ligament of uterus in laparoscopic transabdominal preperitoneal (TAPP) repair of inguinal hernia in women has contended. This study aimed to explore whether there is any difference in the surgical outcome and postoperative complications between the two processing modalities, preservation, and transection of the round ligament of uterus, in adult female inguinal hernia patients undergoing TAPP.

METHODS

Retrospective analysis of 84 female patients (117 sides) who underwent TAPP in XXX Hospital from July 2013 to August 2022. Patient characteristics and technical details of the surgical procedure were collected and divided into two groups according to whether the round ligament of uterus was severed intraoperatively or not. There were 52 cases (77 sides) in the group with preservation of the round ligament of uterus and 32 cases (40 sides) in the group with transection of the round ligament of uterus, comparing the general condition, surgical condition, and the occurrence of postoperative related complications between the 2 groups.

RESULTS

The operative time for unilateral primary inguinal hernia was (129.2 ± 35.1) and (89.5 ± 42.6) minutes in the preservation and transection groups, respectively. There were no statistical differences between the two groups in terms of age, length of hospital stay, ASA, BMI, history of lower abdominal surgery, type and side of hernia, intraoperative bleeding, and time to surgery for primary bilateral hernia (P > 0.05). In addition, there was likewise no statistical difference in the occurrence of postoperative Clavien-Dindo classification, VAS, seroma, mesh infection, labia majora edema, chronic pain or abnormal sensation in the inguinal region, and hernia recurrence in the two groups as well (P > 0.05).

CONCLUSION

There is no evidence that the transection of the round ligament of the uterus during TAPP has an impact on postoperative complications in patients. However, given the important role of the uterine round ligament in the surgical management of patients with uterine prolapse and the high incidence of uterine prolapse in older women, hernia surgeons should also be aware of the need to protect the round ligament of uterus in older women.

Whole genome sequence-based characterization of virulence and antimicrobial resistance gene profiles of Staphylococcus aureus isolated from food poisoning incidents in eastern China

Staphylococcus aureus is an opportunistic foodborne pathogen occasionally isolated from diarrhea patients. In recent years, increasing studies have reported the detection of S. aureus in food poisoning incidents due to food contamination in the North and South of China. However, the epidemiology and genetic characteristics of S. aureus from food poisoning incidents in Eastern China remain unknown. The present study examined the genetic characteristics, antimicrobial resistance, and virulent factors of multidrug-resistant S. aureus isolated from 22 food poisoning incidents reported by the hospitals and health centers in Eastern China from 2011 to 2021. A total of 117 resistant and enterotoxigenic S. aureus isolates were collected and sequenced, among which 20 isolates were identified as methicillin resistant. Genetic analysis revealed 19 distinct CC/ST types, with CC6, CC22, CC59, CC88, and CC398 being the most frequent variants in methicillin-resistant S. aureus (MRSA). A considerable shift in CC types from CC1 to CC398 between 2011 and 2021 was observed in this study, indicating that CC398 may be the main epidemic strain circulating in the current food poisoning incidents. Additionally, genes for enterotoxins were detected in 55 isolates, with a prevalence of 27.8% (27/97) for methicillin-sensitive variants and 35.0% (7/20) for MRSA. The scn gene was detected in 59.0% of the isolates, demonstrating diverse contaminations of S. aureus among livestock-to-human transmission. Of the 117 isolates, only ten isolates displayed multi-drug resistance (MDR) to penicillin, tetracycline, and macrolides. None of the 117 foodborne S. aureus isolates tested positive for vanA in this study. Together, the present study provided phylogenetic characteristics of S. aureus from food poisoning incidents that emerged in Eastern China from 2011 to 2021. Our results suggested that these diarrhea episodes were hypotonic and merely transient low-MDR infections, however, further research for continued surveillance given the detection of virulence and antimicrobial resistance determinants is required to elucidate the genomic characteristics of pathogenic S. aureus in food poisoning incidents in the context of public health.

[Genetic analysis of a family with hereditary hemorrhagic telangiectasia caused by endoglin gene mutation]

Objective: To explore the genetic characteristics of a family with hereditary hemorrhagic telangiectasia (HHT) caused by endoglin (ENG) gene mutations. Methods: A total of 17 individuals from a 3-generation HHT family attending the First Affiliated Hospital of Dali University were selected as the research subjects. Clinical data and familial disease status of the HHT family proband were collected. Whole exome sequencing technology was used to screen for suspected pathogenic genes in the proband, and Sanger sequencing was used for family validation. Results: The proband and her mother had recurrent epistaxis and skin mucosal telangiectasia, and enhanced CT scans of the chest of the proband and her mother, daughter, and cousin indicated the presence of varying degrees of pulmonary arteriovenous malformations. The results of the full exon sequencing results showed that the proband carried the ENG gene c.579_599del non-shift deletion mutation, and Sanger sequencing showed that the mother, daughter, and cousin carried the same mutation. Conclusion: ENG gene c.579_ 599del mutation may be the genetic basis of HHT in this family.

Bevacizumab biosimilar candidate TAB008 compared to Avastin® in patients with locally advanced, metastatic EGFR wild-type non-squamous non-small cell lung cancer: a randomized, double-blind, multicenter study

BACKGROUND

Bevacizumab (Avastin®) is a monoclonal antibody targeting the vascular endothelial growth factor (VEGF). Used alone or in combination with chemotherapy and/or immunotherapy, Avastin® has shown promising efficacy in many cancers. This study compared the efficacy and safety of TAB008 with Avastin® sourced from the EU (bevacizumab-EU), in patients with non-squamous non-small cell lung cancer (nsNSCLC).

METHOD

In this randomized, double-blind, multicenter, phase III similarity study, treatment naïve for metastatic lung cancer., EGFR wild-type, locally advanced, metastatic, or recurrent non-squamous, non-small cell, lung cancer (nsNSCLC) patients were enrolled and randomized (1:1) into TAB008 or Avastin® groups. Patients received TAB008 or Avastin® 15 mg/kg intravenously plus paclitaxel/carboplatin for 4-6 cycles followed by TAB008 or Avastin® 7.5 mg/kg until disease progression, unacceptable toxicity or death. The primary endpoint compared the objective response rate (ORR) within 6 cycles as read by an independent radiological review committee (IRRC). Secondary endpoints compared disease control rate (DCR) Within 6 cycles, duration of response (DoR), progression-free survival (PFS), a year overall survival rate (OSR), overall survival (OS), safety, immunogenicity, and steady-state pharmacokinetics.

RESULTS

A total of 549 nsNSCLC patients were enrolled (277 in TAB008 group and 272 in Avastin® group). In the full analysis set, ORRs were 55.957% for TAB008 and 55.720% for Avastin®, and the ORR ratio was 1 (90% CI 0.89-1.14), well within the predefined equivalence margin of 0.75-1.33. No significant differences were found in DCR within 6 cycles (95.703% vs 95.367%, p = 0.8536), DoR (8.17 vs 7.3 months, p = 0.3526), PFS (9.10 vs. 7.97 months, p = 0.9457), 1 year overall survival rate (66.2% vs 68%, p = 0.6793), or OS (20.4 vs 17.6 months, p = 0.6549). Serious adverse events (SAEs) occurred in 37.55% (104/277) of patients in the TAB008 group and 34.32% (93/271) in the Avastin® group. Anti-drug antibodies were reported in 3 of 277 (1.08%) TAB008 patients, and 5 of 271 (1.85%) Avastin® patients, neutralizing antibody (Nab) was positive in 1 patient on Avastin®, which became negative upon follow-up. The steady-state trough concentrations (Cssmin) were 106.13 μg/mL in TAB008 group and 96.03 μg/mL in Avastin® groups, with the treatment group ratio of LS geometric means fully contained within the bioequivalence limits of 80.00-125.00% (90% CI was 101.74-120.05%).

CONCLUSIONS

TAB008 is similar to Avastin® in terms of efficacy, safety, and pharmacokinetic parameters, with comparable immunogenicity.

TRIAL REGISTRATION

ClinicalTrials.gov number; NCT05427305.

Characterization of microbial community and antibiotic resistome in intra urban water, Wenzhou China

The present study investigated the water quality index, microbial composition and antimicrobial resistance genes in urban water habitats. Combined chemicals testing, metagenomic analyses and qualitative PCR (qPCR) were conducted on 20 locations, including rivers from hospital surrounds (n = 7), community surrounds (n = 7), and natural wetlands (n = 6). Results showed that the indexes of total nitrogen, phosphorus, and ammonia nitrogen of hospital waters were 2-3 folds high than that of water from wetlands. Bioinformatics analysis revealed a total of 1,594 bacterial species from 479 genera from the three groups of water samples. The hospital-related samples had the greatest number of unique genera, followed by those from wetlands and communities. The hospital-related samples contained a large number of bacteria associated with the gut microbiome, including Alistipes, Prevotella, Klebsiella, Escherichia, Bacteroides, and Faecalibacterium, which were all significantly enriched compared to samples from the wetlands. Nevertheless, the wetland waters enriched bacteria from Nanopelagicus, Mycolicibacterium and Gemmatimonas, which are typically associated with aquatic environments. The presence of antimicrobial resistance genes (ARGs) that were associated with different species origins in each water sample was observed. The majority of ARGs from hospital-related samples were carried by bacteria from Acinetobacter, Aeromonas and various genera from Enterobacteriaceae, which each was associated with multiple ARGs. In contrast, the ARGs that were exclusively in samples from communities and wetlands were carried by species that encoded only 1 to 2 ARGs each and were not normally associated with human infections. The qPCR showed that water samples of hospital surrounds had higher concentrations of intI1 and antimicrobial resistance genes such as tetA, ermA, ermB, qnrB, sul1, sul2 and other beta-lactam genes. Further genes of functional metabolism reported that the enrichment of genes associated with the degradation/utilization of nitrate and organic phosphodiester were detected in water samples around hospitals and communities compared to those from wetlands. Finally, correlations between the water quality indicators and the number of ARGs were evaluated. The presence of total nitrogen, phosphorus, and ammonia nitrogen were significantly correlated with the presence of ermA and sul1. Furthermore, intI1 exhibited a significant correlation with ermB, sul1, and bla_SHV, indicating a prevalence of ARGs in urban water environments might be due to the integron intI1's diffusion-promoting effect. However, the high abundance of ARGs was limited to the waters around the hospital, and we did not observe the geographical transfer of ARGs along with the river flow. This may be related to water purifying capacity of natural riverine wetlands. Taken together, continued surveillance is required to assess the risk of bacterial horizontal transmission and its potential impact on public health in the current region.

[Pulmonary vein stenosis with pulmonary infarction secondary to primary mediastinal seminoma: a case report]

Pulmonary vein stenosis is a rare condition that is often underdiagnosed and misdiagnosed. The clinical and radiologic manifestations are unspecific such as cough, hemoptysis and pulmonary lesions and are therefore difficult to distinguished with pneumonia and tuberculosis. The present study is a successful case report of pulmonary vein stenosis and pulmonary infraction secondary to mediastinal seminoma. This case suggested that pulmonary vein stenosis should be considered when a mediastinal mass is accompanied by pulmonary opacites that cannot be explained by common causes such as infection.

[Activation of GABAergic neurons in the zona incerta accelerates anesthesia induction with sevoflurane and propofol without affecting anesthesia maintenance or awakening in mice]

OBJECTIVE

To explore the regulatory effects of GABAergic neurons in the zona incerta (ZI) on sevoflurane and propofol anesthesia.

METHODS

Forty-eight male C57BL/6J mice divided into 8 groups (n=6) were used in this study. In the study of sevoflurane anesthesia, chemogenetic experiment was performed in 2 groups of mice with injection of either adeno-associated virus carrying hM3Dq (hM3Dq group) or a virus carrying only mCherry (mCherry group). The optogenetic experiment was performed in another two groups of mice injected with an adeno-associated virus carrying ChR2 (ChR2 group) or GFP only (GFP group). The same experiments were also performed in mice for studying propofol anesthesia. Chemogenetics or optogenetics were used to induce the activation of GABAergic neurons in the ZI, and their regulatory effects on anesthesia induction and arousal with sevoflurane and propofol were observed; EEG monitoring was used to observe the changes in sevoflurane anesthesia maintenance after activation of the GABAergic neurons.

RESULTS

In sevoflurane anesthesia, the induction time of anesthesia was significantly shorter in hM3Dq group than in mCherry group (P < 0.05), and also shorter in ChR2 group than in GFP group (P < 0.01), but no significant difference was found in the awakening time between the two groups in either chemogenetic or optogenetic tests. Similar results were observed in chemogenetic and optogenetic experiments with propofol (P < 0.05 or 0.01). Photogenetic activation of the GABAergic neurons in the ZI did not cause significant changes in EEG spectrum during sevoflurane anesthesia maintenance.

CONCLUSION

Activation of the GABAergic neurons in the ZI promotes anesthesia induction of sevoflurane and propofol but does not affect anesthesia maintenance or awakening.

[A region-level contrastive learning-based deep model for glomerular ultrastructure segmentation on electron microscope images]

OBJECTIVE

We propose a novel region- level self-supervised contrastive learning method USRegCon (ultrastructural region contrast) based on the semantic similarity of ultrastructures to improve the performance of the model for glomerular ultrastructure segmentation on electron microscope images.

METHODS

USRegCon used a large amount of unlabeled data for pre- training of the model in 3 steps: (1) The model encoded and decoded the ultrastructural information in the image and adaptively divided the image into multiple regions based on the semantic similarity of the ultrastructures; (2) Based on the divided regions, the first-order grayscale region representations and deep semantic region representations of each region were extracted by region pooling operation; (3) For the first-order grayscale region representations, a grayscale loss function was proposed to minimize the grayscale difference within regions and maximize the difference between regions. For deep semantic region representations, a semantic loss function was introduced to maximize the similarity of positive region pairs and the difference of negative region pairs in the representation space. These two loss functions were jointly used for pre-training of the model.

RESULTS

In the segmentation task for 3 ultrastructures of the glomerular filtration barrier based on the private dataset GlomEM, USRegCon achieved promising segmentation results for basement membrane, endothelial cells, and podocytes, with Dice coefficients of (85.69 ± 0.13)%, (74.59 ± 0.13)%, and (78.57 ± 0.16)%, respectively, demonstrating a good performance of the model superior to many existing image-level, pixel-level, and region-level self-supervised contrastive learning methods and close to the fully- supervised pre-training method based on the large- scale labeled dataset ImageNet.

CONCLUSION

USRegCon facilitates the model to learn beneficial region representations from large amounts of unlabeled data to overcome the scarcity of labeled data and improves the deep model performance for glomerular ultrastructure recognition and boundary segmentation.

Counteraction of stability-activity trade-off of Nattokinase through flexible region shifting

The widespread trade-off between stability and activity severely limits enzyme evolution. Although some progresses have been made to overcome this limitation, the counteraction mechanism for enzyme stability-activity trade-off remains obscure. Here, we clarified the counteraction mechanism of the Nattokinase stability-activity trade-off. A combinatorial mutant M4 was obtained by multi-strategy engineering, exhibiting a 20.7-fold improved half-life; meanwhile, the catalytic efficiency was doubled. Molecular dynamics simulation revealed that an obvious flexible region shifting in the structure of mutant M4 was occurred. The flexible region shifting which contributed to maintain the global structural flexibility, was considered to be the key factor for counteracting the stability-activity trade-off. Further analysis illustrated that the flexible region shifting was driven by region dynamical networks reshaping. This work provided deep insight into the counteraction mechanism of enzyme stability-activity trade-off, suggesting that flexible region shifting would be an effective strategy for enzyme evolution through computational protein engineering.

Phylogenetic analysis of the origin and spread of plague in Madagascar

BACKGROUND

Plague is a zoonotic disease caused by the bacterium Yersinia pestis, highly prevalent in the Central Highlands, a mountainous region in the center of Madagascar. After a plague-free period of over 60 years in the northwestern coast city of Mahajanga, the disease reappeared in 1991 and caused several outbreaks until 1999. Previous research indicates that the disease was reintroduced to the city of Mahajanga from the Central Highlands instead of reemerging from a local reservoir. However, it is not clear how many reintroductions occurred and when they took place.

METHODOLOGY/PRINCIPAL FINDINGS

In this study we applied a Bayesian phylogeographic model to detect and date migrations of Y. pestis between the two locations that could be linked to the re-emergence of plague in Mahajanga. Genome sequences of 300 Y. pestis strains sampled between 1964 and 2012 were analyzed. Four migrations from the Central Highlands to Mahajanga were detected. Two resulted in persistent transmission in humans, one was responsible for most of the human cases recorded between 1995 and 1999, while the other produced plague cases in 1991 and 1992. We dated the emergence of the Y. pestis sub-branch 1.ORI3, which is only present in Madagascar and Turkey, to the beginning of the 20th century, using a Bayesian molecular dating analysis. The split between 1.ORI3 and its ancestor lineage 1.ORI2 was dated to the second half of the 19th century.

CONCLUSIONS/SIGNIFICANCE

Our results indicate that two independent migrations from the Central Highlands caused the plague outbreaks in Mahajanga during the 1990s, with both introductions occurring during the early 1980s. They happened over a decade before the detection of human cases, thus the pathogen likely survived in wild reservoirs until the spillover to humans was possible. This study demonstrates the value of Bayesian phylogenetics in elucidating the re-emergence of infectious diseases.

Molecular Characteristics of Methicillin-Resistant and Susceptible Staphylococcus aureus from Pediatric Patients in Eastern China

Staphylococcus aureus is an opportunistic pathogen that causes invasive infections in humans. In recent years, increasing studies have focused on the prevalence of S. aureus infections in adults; however, the epidemiology and molecular characteristics of S. aureus from Chinese pediatric patients remain unknown. The present study examined the population structure, antimicrobial resistance, and virulent factors of methicillin-resistant and -susceptible S. aureus isolated from Chinese pediatric patients from one medical center in eastern China. A total of 81 cases were screened with positive S. aureus infections among 864 pediatric patients between 2016 and 2022 in eastern China. Molecular analysis showed that ST22 (28.4%) and ST59 (13.6%) were the most typical strains, and associations between different clonal complex (CC) types/serotype types (ST) and the age of pediatric patients were observed in this study. CC398 was the predominant type in neonates under 1 month of age, while CC22 was mainly found in term-infant (under 1 year of age) and toddlers (over 1 year of age). Additionally, 17 S. aureus isolates were resistant to at least three antimicrobials and majority of them belonged to CC59. The blaZ gene was found in 59 isolates and mecA gene was present in 26 strains identified as methicillin-resistant. Numerous virulent factors were detected in S. aureus isolated from present pediatric patients. Remarkably, lukF-PV and lukS-PV were dominantly carried by CC22, tsst-1 genes were detected in CC188, CC7, and CC15, while exfoliative toxin genes were found only in CC121. Only 41.98% of the S. aureus isolates possessed scn gene, indicating that the sources of infections in pediatric patients may include both human-to-human transmissions as well as environmental and nosocomial infections. Together, the present study provided a phylogenetic and genotypic comparison of S. aureus from Chinese pediatric patients in Suzhou city. Our results suggested that the colonization of multi-drug resistant isolates of S. aureus may raise concern among pediatric patients, at least from the present medical center in eastern China.

[Analysis of the pathogenesis and risk factors of gallstone]

Objective: To explore the pathogenesis and risk factors of gallstone formation. Methods: The findings of hepatobiliary ultrasound and related data were collected from healthy subjects who underwent a physical examination at Xuanwu Hospital of Capital Medical University from January 2012 to December 2021. A total of 98 344 healthy subjects were included in the study,including 48 241 males and 50 103 females,with a ratio of 1∶1.03,aged (42.0±15.6)years(range:14 to 97 years). The gender,age,body mass index,waist circumference,systolic pressure,diastolic pressure,ALT,AST,total bilirubin,fasting blood glucose,triglyceride,total cholesterol,low-density lipoprotein,high-density lipoprotein were collected.Healthy subjects were required to sit for at least 10 minutes before blood pressure was measured.Rresults of fasting venous blood were collected after 8 to 12 hours on an empty stomach.According to the presence of gallstones by ultrasound results, healthy subjects were divided into study group and control group. Data were analyzed by rank-sum tests and χ² test, and risk factors for gallstone formation were explored by Logistic regression analysis. Results: The incidence of gallstones in this group was 5.42%(5 333/98 344). Among them,the incidence of gallstones in people aged 60 years and above was significantly higher than that in people under 60 years old(15.31%(2 348/15 334) vs. 3.60%(2 985/83 010), χ²=3 473.46,P<0.05).The healthy subjects were divided by age for every 10 years,and the results showed that the incidence of gallstones increased with age. The incidence of gallstones in females was 5.68%(2 844/50 103),greater than 5.16%(2 489/48 241) in males(χ²=11.81,P<0.05). Among them,1 478 cases underwent gallbladder surgical resection due to gallstones,and the operation rate was 27.71%. The operation rate reached the peak between 60 and <70 years old,and decreased after 70 years old. The results of the multivariate analysis showed that,female(OR=1.38, P<0.01),age(OR=1.58, P<0.01),body mass index≥24 kg/m²(OR=1.31, P<0.01),waist circumference≥85 cm(OR=1.24, P<0.01),fasting blood glucose>6.1 mmol/L(OR=1.18,P<0.01),total cholesterol≥5.18 mmol/L(OR=0.87, P=0.019),low-density lipoprotein≥3.37 mmol/L(OR=1.15,P=0.001) were the risk factors for gallstone formation;high-density lipoprotein≥1.55 mmol/L(OR=0.87, P<0.01) was a protective factor for gallstone formation. Conclusions: The incidence of gallstones increases with age in male and female. Gender,age,body mass index,waist circumferenc,fasting blood glucose,total cholesterol,LDL,and HDL are related factors with gallstone formation.

Genomic Analysis Revealed the International and Domestic Transmission of Carbapenem-Resistant Klebsiella pneumoniae in Chinese Pediatric Patients

Carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a severe threat to public health worldwide. Based on the genomic analysis of 198 CRKP isolates collected at Shanghai Children's Medical Center over the last 8 years (2013 to 2021), we reported the clinical risk, genetic diversity, and prevalence of antimicrobial resistance (AMR) of CRKP in pediatric patients at the genomic level. We found that the blaNDM genes were the predominant carbapenemase genes, followed by blaKPC-2 and blaIMP. All of the carbapenemases were disseminated mainly by four main types of plasmids, among which one plasmid was associated with a higher risk of bloodstream infections. Notably, we tracked disease outbreaks caused by recent introductions of ST14 CRKP from southeast Asia or western countries, and we reported frequent, repetitive introductions of ST11 from other domestic hospitals that were associated interhospital movement of the patients. The cocirculation of K. pneumoniae and AMR plasmids in hospitals highlights the importance of genome sequencing for monitoring and controlling CRKP infections. IMPORTANCE Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection in pediatric patients differs from that in adults patients in terms of both genetic and phenotypic features, which remain to be elucidated. We present a summary of prevalent CRKP isolates from Chinese pediatric patients over 8 years, demonstrating the prevalence and clinical importance of New Delhi metallo-β-lactamase genes in pediatric patients, mainly describing the genomic features of two predominant CRKP clones (ST11 and ST14) in Chinese children, and identifying four carbapenemase-encoding plasmids that contribute to the transmission of most carbapenemase genes in hospitals. Overall, our research provides valuable information about the international and domestic transmission of CRKP isolates that are prevalent in Chinese children and shows the urgent need for genome sequencing-based surveillance systems for monitoring the transmission of CRKP.

Uniaxial cyclic stretch enhances osteogenic differentiation of OPLL-derived primary cells via YAP-Wnt/β-catenin axis

The pathogenesis of posterior longitudinal ligament ossification (OPLL) remains inadequately understood. Mechanical stimulation is one of the important pathogenic factors in OPLL. As one of the mechanical stimulation transduction signals, the yes-associated protein (YAP) interacts with the Wnt/β-catenin signalling pathway, which plays an important role in osteogenic differentiation. This study aimed to demonstrate the role of YAP-Wnt/β-catenin axis in cell differentiation induced by mechanical stress. Primary cells extracted from posterior longitudinal ligament tissues from OPLL or non-OPLL patients were subjected to sinusoidal uniaxial cyclic stretch (5 %, 0.5 Hz, 3 d). The expression of runt-related transcription factor 2, collagen I, osterix, osteocalcin and alkaline phosphatase were compared between the static and the experimental groups. In addition, the cytoskeleton was detected using phalloidin staining while YAP phosphorylation states and nuclear location were identified using immunofluorescence. The results showed that mechanical stretching loading increased the expression of osteogenic genes and proteins in the OPLL group, while it had no significant effect on the control group. When OPLL cells were stretched, YAP exhibited an obvious nuclear translocation and the Wnt/β-catenin pathway was activated. Knocking down YAP or β-catenin could weaken the impact upon osteogenic differentiation induced by mechanical stimulation. YAP-mediated mechanical stimulation promoted osteogenic differentiation of OPLL cells through Wnt/β-catenin pathway and this progress was independent of the Hippo pathway.

[Prevalence and molecular characterization of Cryptosporidium in captive-bred Mustela putorius furo in Jiangsu Province]

OBJECTIVE

To investigate the prevalence and molecular features of Cryptosporidium in captive-bred Mustela putorius furo in Jiangsu Province.

METHODS

A total of 290 fresh stool samples were collected from a ferret farm in Jiangsu Province on May 2017, and the small subunit rRNA (SSU rRNA) gene of Cryptosporidium was amplified in stool samples using nested PCR assay. The actin, cowp and gp60 genes were amplified in positive samples and sequenced to characterize Cryptosporidium species/genotypes.

RESULTS

A total of 18 stool samples were tested positive for Cryptosporidium SSU rRNA gene, with a detection rate of 6.2%. Sequence and phylogenetic analyses of SSU rRNA, actin and cowp genes characterized Cryptosporidium isolated from captive-bred ferrets as Cryptosporidium sp. ferret genotype. In addition, gp60 gene was amplified in 10 out of 18 stool samples tested positive for Cryptosporidium.

CONCLUSIONS

Cryptosporidium is widely prevalent in captive-bred ferrets in Jiangsu Province, and Cryptosporidium sp. ferret genotype is the only Cryptosporidium genotype in ferrets.