Zymograph profiling reveals a divergent evolution of sirtuin that may originate from class III enzymes.

Sirtuins are a group of NAD+-dependent deacylases that conserved in three domains of life and comprehensively involved in the regulation of gene transcription, chromosome segregation, RNA splicing, apoptosis, and aging. Previous studies in mammalian cells have revealed that sirtuins not only exist as multiple copies, but also show distinct deacylase activities in addition to deacetylation. However, the understanding of sirtuin zymographs in other organisms with respect to molecular evolution remains at an early stage. Here, we systematically analyze the sirtuin activities in representative species from archaea, bacteria, and eukaryotes, using both the HPLC assay and a 7-amino-4-methylcoumarin-based fluorogenic method. Global profiling suggests that the deacylase activities of sirtuins could be divided into three categories and reveals undifferentiated zymographs of class III sirtuins, especially for those from bacteria and archaea. Nevertheless, initial differentiation of enzymatic activity was also observed for the class III sirtuins at both paralog and ortholog levels. Further phylogenetic analyses support a divergent evolution of sirtuin that may originate from class III sirtuins. Together, this work demonstrates a comprehensive panorama of sirtuin zymographs and provides new insights into the cellular specific regulation and molecular evolution of sirtuins.

Synthesis of Calix[4]arene-Based Porous Organic Cages and Their Gas Adsorption.

Two crystalline large-sized porous organic cages (POCs) based on conical calix[4]arene (C4A) were designed and synthesized. The four-jaw C4A unit tends to follow the face-directed self-assembly law with the planar triangular building blocks such as tris(4-aminophenyl)amine (TAPA) or 1,3,5-tris(4-aminophenyl)benzene (TAPB) to generate a predictable cage with a stoichiometry of [6+8]. The formation of the large cages is confirmed through their relative molecular mass measured using MALDI-TOF/TOF spectra. The protonated molecular ion peaks of C4A-TAPA and C4A-TAPB were observed at m/z 5109.0 (calculated for C336H240O24N32: m/z 5109.7) and m/z 5594.2 (calculated for C384H264O24N24: m/z 5598.4). C4A-POCs exhibit I-type N2 adsorption-desorption isotherms with the BET surface areas of 1444.9 m2 ⋅ g-1 and 1014.6 m2 ⋅ g-1. The CO2 uptakes at 273 K are 62.1 cm3 ⋅ g-1 and 52.4 cm3 ⋅ g-1 at a pressure of 100 KPa. The saturated iodine vapor static uptakes at 348 K are 3.9 g ⋅ g-1 and 3.5 g ⋅ g-1. The adsorption capacity of C4A-TAPA for SO2 reaches to 124.4 cm3 ⋅ g-1 at 298 K and 1.3 bar. Additionally, the adsorption capacities of C4A-TAPA for C2H2, C2H4, and C2H6 were evaluated.

Antibiotic resistance of Helicobacter pylori in Chinese children: A multicenter study from 2016 to 2023.

BACKGROUND: To investigate the antibiotic resistance of Helicobacter pylori (H. pylori) strains to clarithromycin, metronidazole, amoxicillin, levofloxacin, furazolidone, and tetracycline in Chinese children. MATERIALS AND METHODS: This multicenter, retrospective study was conducted from January 2016 through May 2023. Gastric mucosa biopsies were obtained from pediatric participants who underwent upper gastrointestinal endoscopy at 96 hospitals in northern, southwestern, and southeastern China. The susceptibility of H. pylori to six commonly used antibiotics was determined by agar dilution method. RESULTS: Among the 3074 H. pylori isolates, 36.7% were resistant to clarithromycin, 77.3% to metronidazole, 16.6% to levofloxacin, and 0.3% to amoxicillin. No strains were detected to be resistant to furazolidone or tetracycline. During the 8-year study period, resistance to clarithromycin and metronidazole showed a significant upward trend, while the resistance pattern of the other antibiotics demonstrated a slight but nonsignificant fluctuation. Significant regional differences were found in the distribution of clarithromycin resistance among the northern (66.0%), southwestern (48.2%), and southeastern (34.6%) regions. The metronidazole resistance rate was significantly lower in the southeastern coastal region (76.3%) than in the other two regions (88.2% in the north and 87.7% in the southwest). Multi-drug resistance for two or more antibiotics was detected in 36.3% of the H. pylori strains, and the predominant multi-resistance pattern was the dual resistance to clarithromycin and metronidazole. CONCLUSIONS: The prevalence of H. pylori resistance to clarithromycin and metronidazole is rather high in Chinese children and has been increasing over time. A relatively high resistance rate to levofloxacin was also noticed in children, while almost all strains were susceptible to amoxicillin, furazolidone, and tetracycline. It will be of great clinical significance to continuously monitor the antibiotic-resistance patterns of H. pylori in the pediatric population.

[Value of different endoscopic scoring methods in assessing disease activity in pediatric Crohn's disease]. / ä¸åŒå† é•œè¯„åˆ†æ³•è¯„ä¼°å„¿ç«¥å ‹ç½—æ©ç— ç–¾ç— æ´»åŠ¨åº¦çš„ä»·å€¼.

OBJECTIVES: To explore the value of different endoscopic scoring methods in assessing disease activity in pediatric Crohn's disease (CD). METHODS: A total of 70 children diagnosed with CD at the Children's Hospital of Chongqing Medical University from January 2018 to January 2023 were included. Clinical disease activity was assessed using the Pediatric Crohn's Disease Activity Index (PCDAI), while different endoscopic scores were assigned based on endoscopic findings. Spearman rank correlation analysis was used to evaluate the correlation between each endoscopic scoring method and PCDAI as well as laboratory indicators. Kappa test was used to assess the consistency between colonoscopy/capsule endoscopy scoring methods and PCDAI in determining CD activity. Receiver operating characteristic curve analysis was performed to assess the diagnostic efficacy of laboratory indicators in predicting endoscopic activity. RESULTS: The PCDAI score showed a moderate positive correlation with the scores of Crohn's Disease Endoscopic Index of Severity (CDEIS) (rs=0.696, P<0.01), Simple Endoscopic Score for Crohn's Disease (SES-CD) (rs=0.680, P<0.01), Lewis Score (rs=0.540, P<0.01), and Capsule Endoscopy-Crohn's Disease Index (CE-CD) (rs=0.502, P<0.01). The consistency between all endoscopic scoring methods and PCDAI in determining CD activity was poor (Kappa=0.069-0.226). Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), hematocrit (HCT), and serum albumin (ALB) levels showed a moderate correlation with the PCDAI score and the scores of colonoscopy scoring methods (CDEIS and SES-CD) (|rs|=0.581-0.725, P<0.01), but a weak correlation with the scores of capsule scoring methods (P<0.05). ESR and CRP had higher area under the curve (AUC) values in predicting disease activity based on PCDAI, CDEIS, SES-CD, and Lewis Score compared to HCT and ALB (P<0.05). CONCLUSIONS: CDEIS, SES-CD, Lewis Score, and CE-CD can be used to evaluate disease activity in pediatric CD, but they do not fully correspond with disease activity assessed by PCDAI. Elevated levels of ESR and CRP can predict clinical and endoscopic disease activity in children with CD.

Calix[4]arene-Derived 2D Covalent Organic Framework with an Electron Donor-Acceptor Structure: A Visible-Light-Driven Photocatalyst.

The calixarenes are ideal building blocks for constructing photocatalytic covalent organic frameworks (COFs), owing to their electron-rich and bowl-shaped π cavities that endow them with electron-donating and adsorption properties. However, the synthesis and structural confirmation of COFs based on calixarenes are still challenging due to their structural flexibility and conformational diversity. In this study, a calix[4]arene-derived 2D COF is synthesized using 5,11,17,23-tetrakis(p-formyl)-25,26,27,28-tetrahydroxycalix[4]arene (CHO-C4A) as the electron donor and 4,7-bis(4-aminophenyl)-2,1,3-benzothiadiazole (BTD) as the acceptor. The powder X-ray diffraction data and theoretical simulation of crystal structure indicate that COF-C4A-BTD exhibits high crystallinity and features a non-interpenetrating undulating 2D layered structure with AA-stacking. The density functional theory theoretical calculation, transient-state photocurrent tests, and electrochemical impedance spectroscopy confirm the intramolecular charge transfer behavior of COF-C4A-BTD with a donor-acceptor structure, leading to its superior visible-light-driven photocatalytic activity. COF-C4A-BTD exhibits a narrow band gap of 1.99 eV and a conduction band energy of -0.37 V versus normal hydrogen electrode. The appropriate energy band structure can facilitate the participation of ·O2- and h+ . COF-C4A-BTD demonstrates high efficacy in removing organic pollutants, such as bisphenol A, rhodamine B, and methylene blue, with removal rates of 66%, 85%, and 99% respectively.

The Fabrication and Mechanism of a Crystalline Organic Fluorescent Probe Based on Photoinduced Electron Transfer.

The response performances of the crystalline organic fluorescence probe are highly dependent on the long-range ordered arrangement of crystalline structure. Herein, a novel organic crystalline fluorescent probe with a high quantum yield was established through the rapid self-assembly of 1,2,4,5-Tetrakis (4-carboxyphenyl) benzene (H4TCPB) and DMF molecules. Each H4TCPB, which connects to four DMF molecules through hydrogen bonds, acts as the structural unit. The building units are packed by π-π, lone pair···π, and lone pair···lone pair interactions to form solid-state crystalline materials. H4TCPB·4DMF exhibits distinct blue fluorescent under UV light, while the quantum yield is as high as 89.02% and the fluorescence lifetime is 1.95 ns. The H4TCPB·4DMF nanocrystal exhibits a specific fluorescence quench sensibility to tetracycline (TC), compared with the common chemicals and ions in environmental water. Moreover, the test results can be obtained quickly and are easily visible to the naked eye. The limit of detection for TC is as low as 12 nM in an aqueous solution. Spectral analysis and density functional theory (DFT) theoretical calculations were used to explain the fluorescence quenching mechanism of H4TCPB·4DMF toward TC, which could be attributed to the photoinduced electron transfer occurring from H4TCPB·4DMF to TC. Our work enriches the database of crystalline luminescent materials and provides theoretical support for the design and mechanical studies of organic fluorescent probes.

Antibiotic resistance of Helicobacter pylori isolated from children in Chongqing, China.

The resistance of Helicobacter pylori (H. pylori) to antibiotics has been increasing worldwide and varies across different geographic areas and times. Limited studies reported the prevalence of antibiotic resistance and its related gene mutations in children in Chongqing, a city located in southwest China. We collected 112 H. pylori strains isolated from gastric biopsies of 156 children at Children's Hospital of Chongqing Medical University and calculated resistance rates of these strains to six antibiotics. The A2143G and A2142G mutations in 23S rRNA gene, which are related to clarithromycin resistance, and Asn87 and Asp91 mutations in gyrA gene, which are related to levofloxacin resistance, were investigated in 102 strains. The resistance rates to clarithromycin, metronidazole, and levofloxacin were 47.3% (53/112), 88.4% (99/112), and 18.8% (21/112), respectively. No resistance to amoxicillin, tetracycline, and furazolidone was observed. Dual and triple resistance percentages were 37.5% (42/112) and 10.7% (12/112), respectively. The detection rate of A2143G mutation in 23S rRNA gene was 83.3% (40/48). The detection rates of mutations of Asn87 and Asp91 in gyrA gene were 52.6% (10/19) and 36.8% (7/19), respectively. Conclusion: The prevalence of H. pylori resistance to clarithromycin, metronidazole, and levofloxacin was high in children in Chongqing, China. The A2143G mutation was detected in most clarithromycin-resistant strains, and Asn87 and Asp91 of gyrA mutation points were common in levofloxacin-resistant strains. In clinical practice, anti-H. pylori therapy should be individualized based on a susceptibility test.  What is Known: • The resistance of H. pylori to antibiotics changes with the geographic areas and that in Asia the resistance rate is high. • Mutation plays a vital role in antibiotics resistance of H. pylori. What is New: • High resistance rates to single and multiple antibiotics in children of Chongqing, a city located in southwest China, were observed. • Molecular assays showed good conformance with susceptibility test results to direct antibiotic resistance of H. pylori.

[Clinical features of children with colorectal polyps and the efficacy of endoscopic treatment: an analysis of 1 351 cases]. / å„¿ç«¥ç»“ç›´è‚ æ¯è‚‰1 351ä¾‹çš„ä¸´åºŠç‰¹å¾åŠå† é•œä¸‹æ²»ç–—æ•ˆæžœåˆ†æž.

OBJECTIVES: To study the clinical features of children with colorectal polyps and the efficacy of endoscopic treatment. METHODS: A retrospective analysis was performed on the medical data of 1 351 children with colorectal polyps who were admitted and received colonoscopy and treatment in the past 8 years, including clinical features and the pattern and outcomes of endoscopic treatment. RESULTS: Among the 1 351 children, 893 (66.10%) were boys and 981 (72.61%) had an age of 2-<7 years, and hematochezia (1 307, 96.74%) was the most common clinical manifestation. Of all the children, 89.27% (1 206/1 351) had solitary polyps, and 95.77% (1 290/1 347) had juvenile polyps. The polyps were removed by electric cauterization with hot biopsy forceps (6 cases) or high-frequency electrotomy and electrocoagulation after snare ligation (1 345 cases). A total of 1 758 polyps were resected, among which 1 593 (90.61%) were pedunculated and 1 349 (76.73%) had a diameter of <2 cm. Postoperative complications included bleeding in 51 children (3.77%), vomiting in 87 children (6.44%), abdominal pain in 14 children (1.04%), and fever in 39 children (2.89%), while no perforation was observed. The children aged <3 years had the highest incidence rates of postoperative bleeding and fever (P<0.0125), and the children with a polyp diameter of ≥2 cm had significantly higher incidence rates of postoperative bleeding, vomiting, and fever (P<0.05). CONCLUSIONS: Solitary polyps, pedunculated polyps, and juvenile polyps are common types of pediatric colorectal polyps. Electric cauterization with hot biopsy forceps or high-frequency electrotomy and electrocoagulation after snare ligation can effectively remove colorectal polyps in children, with good efficacy and few complications. Younger age and larger polyp diameter are associated with a higher risk of postoperative bleeding.

The diagnostic value of APT for food allergy in children: a systematic review and meta-analysis.

BACKGROUND: The role of atopy patch test (APT) in the diagnosis of food allergy (FA) remains largely controversial. In our meta-analysis, we aimed to evaluate the accuracy of APT for diagnosing FA in children. METHODS: Pubmed, Embase and Cochrane Library were searched for studies regarding the diagnostic value of APT for FA in children compared to oral food challenge (double-blind placebo-controlled food challenge and/or open food challenge). The last search was conducted on November 11, 2017. Two reviewers independently screened relevant studies and assessed the quality by QUADAS-2. Meta-analysis was performed to calculate the pooled sensitivity, specificity, DOR (diagnostic odds ratio), PLR (positive likelihood ratio), NLR (negative likelihood ratio) with their 95% confidence intervals (CIs). Subgroup analyses were conducted according to different food allergens, atopic dermatitis, gastrointestinal symptoms, and age younger than 3 years. RESULTS: Forty-one studies were included in the meta-analysis. The pooled sensitivity, specificity, PLR, NLR and DOR were 50.30% (95% CI 48.40%-52.30%), 86.60% (95% CI 85.30%-87.80%), 3.405 (95% CI 2.594-4.470), 0.545 (95% CI 0.469-0.634) and 7.528 (95% CI 5.507-11.206), respectively. However, for children with FA-related gastrointestinal symptoms, the pooled sensitivity and specificity were 57.40% (95% CI 52.10%-62.50%) and 91.50% (95% CI 88.30%-94.10%) respectively. CONCLUSIONS: Our findings suggest that APT is specific but not sensitive for diagnosing FA in children, especially in children with FA-related gastrointestinal symptoms.

Efficacy of Lactobacillus-supplemented triple therapy for Helicobacter pylori infection in children: a meta-analysis of randomized controlled trials.

Therapy-related side effects and severe antimicrobial resistance still remain an obstacle to Helicobacter pylori eradication. This meta-analysis aimed to investigate the efficacy of Lactobacillus-supplemented triple therapy on H. pylori eradication rates and therapy-related side effects in children. Five studies involving 484 pediatric patients were included in our analysis. The pooled relative risk (RR) for eradication rates in the Lactobacillus group versus the control group was 1.19 [95% confidence interval (CI) 1.07-1.33]. In subgroup analyses based on dose and duration of Lactobacillus supplementation, the pooled RRs for eradication rates were 1.36 (95% CI 1.15-1.60) in the high-dose group, 1.08 (95% CI 0.86-1.35) in the low-dose group, 1.24 (95% CI 1.06-1.46) in the long-term group, and 1.17 (95% CI 0.96-1.44) in the short-term group. With respect to side effects, Lactobacillus supplementation significantly reduced the incidence of diarrhea (RR = 0.30, 95% CI 0.10-0.85).Conclusions: Lactobacillus, as an adjunct to triple therapy, can increase H. pylori eradication rates as well as reduce the incidence of therapy-related diarrhea in children. And a higher dose and a longer duration of supplementation may conduce to the positive impact of Lactobacillus on H. pylori eradication. What is Known: • Probiotics-supplemented triple therapy may be beneficial in improving H. pylori eradication rates and reducing therapy-related side effects in children. However, not all probiotics are beneficial to H. pylori eradication and the pooled outcomes based on different probiotics may be erroneously extrapolated to other ineffective strains. What is New: • Lactobacillus, as an adjunct to triple therapy, can increase H. pylori eradication rates as well as reduce the incidence of therapy-related diarrhea in children.

A porous aromatic framework as a versatile fiber coating for solid-phase microextraction of polar and nonpolar aromatic organic compounds.

A porous aromatic framework (PAF) derived from triphenylamine (type PAF-41) was prepared and is shown to be a viable coating for fibrous solid-phase microextraction (SPME). PAF-41 can be easily synthesized and has a high surface area, a rich π-electron structure, and electron-rich nitrogen atoms in its framework. The PAF-41-coated fibrous SPME extractor was combined with a gas chromatographic separation and flame ionization detection. The method was applied to the quantitation of some aromatic organic compounds (AOCs), including polar amphetamine and methamphetamine and nonpolar ethylbenzene, o-, m- and p-xylenes, and styrene. The method was optimized after which a linear response is found for the 10-500 ng·mL-1 amphetamine and methamphetamine concentration ranges. The limits of detection are 1.0 and 0.5 ng·mL-1; and relative standard deviations for six repeated extractions with a single fiber are 5.3 and 6.7%. The method was applied for the determination of amphetamine and methamphetamine in spiked urine samples without any pretreatment except for dilution with water. The PAF-41 modified fiber also was applied to the extraction of styrene, xylenes and ethylbenzene. The enrichment capacities of the extractor for these AOCs were superior to those of commercial SPME extractors. Graphical abstract (a) Schemetic of the PAF-41-coated solid-phase microextraction (SPME) fiber. (b) Scanning electron microscope images of the PAF-41 fiber.

[Research advances in influencing factors for immune tolerance to food allergens in children].

Food allergen-specific immune tolerance is defined as nonresponsiveness of the adaptive immune system to food antigens. Failed development or inhibition of such tolerance may cause food allergy. With the increasing incidence rate of food allergy year by year, more and more studies have found the association between food allergy and various diseases. The development of food allergen-specific immune tolerance in childhood has been taken more and more seriously. In recent years, many studies have shown that the development of food allergen-specific immune tolerance is influenced by various factors, which can be roughly divided into antigens, organisms, and environment. This article reviews the influencing factors for the development of immune tolerance to food allergens in children, in order to provide help for reducing the incidence of food allergy and improving the prognosis of food allergy.

[Clinical features and etiology of abdominal distension in children].

OBJECTIVE: To study the clinical features and etiology of abdominal distension in children with different ages. METHODS: A retrospective analysis was performed for the clinical data of 1 561 children who were admitted due to abdominal distension from January 2013 to October 2016, including clinical manifestations, radiological examination, pathological results, and disease diagnosis. RESULTS: Among the 1 561 children, there were 823 neonates (aged <28 days), 307 infants (aged 28 days to 1 year), 186 toddlers (aged 1-3 years), 120 preschool children (aged 3-6 years), 106 school-aged children (aged 6-12 years), and 19 adolescents (aged 12-17 years). Vomiting was the major associated symptom in neonates, infants, toddlers, and school-aged children, abdominal pain was the major associated symptom in pre-school children, and vomiting and abdominal pain were the major associated symptoms in adolescents. Hypoactive bowel sound was the major accompanying sign in neonates and infants, and abdominal tenderness was the major accompanying sign in the other four age groups. Plain abdominal radiograph showed intestinal inflation in neonates and intestinal inflation with an air-fluid level in the other five age groups. Histopathological examination was performed for 339 children and the pathological results of intestinal tissue showed small, few, or poorly developed submucosal ganglion cells in neonates, intestinal inflammation/bleeding/necrosis in infants, and appendicitis in the other age groups. Necrotizing enterocolitis was the main cause of abdominal distension in neonates (34.4%), and intestinal obstruction was the main cause in infants (36.8%), toddlers (52.2%), pre-school children (51.7%), school-aged children (62.3%), and adolescents (52.6%). CONCLUSIONS: Vomiting is a common symptom in children with abdominal distension in all age groups. Neonates and infants with abdominal distension often present with hypoactive bowel sounds, and children over 1 year old mainly suffer from abdominal tenderness. Necrotizing enterocolitis is the most common cause of neonatal abdominal distension, and abdominal distension in the other age groups is mainly attributed to intestinal obstruction.

Porous Aromatic Framework 48/Gel Hybrid Material Coated Solid-Phase Microextraction Fiber for the Determination of the Migration of Styrene from Polystyrene Food Contact Materials.

A novel solid-phase microextraction (SPME) fiber was fabricated by a porous aromatic framework 48 (PAF-48)/gel hybrid material through a sol-gel process. PAF-48 is a porous organic framework (POF) material that was polymerized from 1,3,5-triphenylbenzene. The uniform pore structure, high surface area, continuous conjugate network, and hydrophobicity make PAF-48 expected to have special abilities to absorb and extract styrene as well as some other harmful volatile aromatic compounds (VACs). The PAF-48/gel-coated fiber was explored for the extraction of styrene and six VACs (benzene, toluene, ethylbenzene, and xylenes) from aqueous food simulants followed by gas chromatography (GC) separation. The fiber was found to be very sensitive for the determination of the target molecules with wide linear ranges (0.1-200 or 500 µg·kg-1), low limits of detection (LODs, 0.003-0.060 µg·kg-1), acceptable precisions (intraday relative standard deviation, RSD < 5.9%, interday RSD < 7.3%), and long lifetime (>200 times). Particularly for styrene, the PAF-48/gel-coated fiber exhibited a much lower LOD (0.006 µg·kg-1) compared with most of the reported fibers. Moreover, the PAF-48/gel-coated fiber had a high extraction selectivity for styrene and VACs over alcohols, phenols, aromatic amines, and alkanes and show a molecular sieving effect for the different molecule sizes. Finally, the PAF-48/gel-coated SPME fiber was successfully applied in GC for the determination of the specific migrations of styrene and VACs from polystyrene (PS) plastic food contact materials (FCMs).

Fish intake during pregnancy or infancy and allergic outcomes in children: A systematic review and meta-analysis.

It has been suggested that n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs) have anti-inflammatory properties and may reduce the risk of allergic disease. Fish is a great source of n-3 LC-PUFAs. However, the effect of fish on allergic disease remains controversial. PubMed, EMBASE, and Cochrane Central Register of Controlled Trials were searched for randomized controlled trials (RCTs) and prospective cohort studies regarding the effect of fish intake during pregnancy or infancy on allergic outcomes in children. The outcomes of interest were atopy, eczema, allergic rhinitis, wheeze, asthma, and food allergy. One RCT and 17 publications from 13 prospective cohort studies were included for maternal fish intake during pregnancy, and eight publications from five prospective cohort studies for fish intake in infancy. Pooled analysis suggested that maternal fish intake during pregnancy was not associated with lower risk of any allergic outcome, both in RCT and observational studies. Consumption of fish during the first year of life reduced the risk of eczema (RR 0.61; 95% CI 0.47, 0.80; p = 0.0003; I2  = 68%) and allergic rhinitis (RR 0.54; 95% CI 0.36, 0.81; p = 0.003; I2  = 74%). Current evidence indicates that fish intake in infancy could reduce the risk of eczema and allergic rhinitis in children, whereas maternal fish intake during pregnancy does not affect any atopic outcome. The intake of fish per se in infancy, not specially n-3 LC-PUFAs, may have an allergy protective effect. High-quality and adequately powered RCTs are warranted to confirm this.

Effect of vitamin A and Zn supplementation on indices of vitamin A status, haemoglobin level and defecation of children with persistent diarrhea.

To investigate the effect of vitamin A and Zn supplementation on vitamin A status, haemoglobin level and defecation of children with persistent diarrhea, a total of 160 paediatric patients were randomly assigned to one of four intervention groups: daily supplementation of 1,500 IU VA for 14 days; daily Zn supplementation for 14 days; daily supplementation with both VA and Zn for 14 days; no supplementation. One hundred twenty-seven children with persistent diarrhea finished intervention (33 were lost to follow-up). Among the 127 children, 41 (32.28%) had anaemia, 104 (81.89%) had a VA deficiency and 38 (29.92%) had an iron insufficiency. Supplementation with VA or VA + Zn enhanced the serum VA levels and ameliorated anaemia. Supplementation with Zn and VA + Zn for 5 days significantly improved defecation, where the VA + Zn treatment resulted in superior outcomes. After 14 days of intervention, the total effectiveness rates were 93.94%, 96.77% and 96.67% in the three groups, significantly greater than that of the non-supplementation group (72.73%). These results indicate that single VA or concurrent VA + Zn supplementation can improve vitamin A status, haemoglobin level and defecation. However, concurrent VA + Zn supplementation is the optimal option and can shorten the duration of persistent diarrhea and markedly improve nutritional status. (www.clinicaltrials.gov registration number: ChiCTR-IOR-14005498).

Vitamin A deficiency impacts the structural segregation of gut microbiota in children with persistent diarrhea.

To investigate whether gut microbiota is associated with vitamin A nutritional levels in children with persistent diarrhea, a total of 59 pediatric patients with persistent diarrhea aged 1-12 months were selected from the Department of Gastroenterology at the Children's Hospital of Chongqing Medical University, China. Subjects were hospitalized and divided into VA-deficient (n = 30) and VA-normal (n = 29) groups according to their venous serum retinol levels. Fecal samples from all 59 subjects were collected immediately after admission and analyzed by Illumina MiSeq for 16S rRNA genes to characterize the overall microbiota of the samples. The gut microbiota of the VA-deficient and VA-normal groups were compared using a bioinformatic statistical approach. The Shannon index (p = 0.02), Simpson index (p = 0.01) and component diagram data indicated significantly lower diversity in the VA-deficient than the VA-normal group. A metagenome analysis (LEfSe) and a differentially abundant features approach using Metastats revealed that Escherichia coli and Clostridium butyricum were the key phylotypes of the VA-normal group, while Enterococcus predominated the VA-deficient group. In conclusion, the diversity of gut microbiota and the key phylotypes are significantly different in children with persistent diarrhea at different VA nutritional levels.

Combinatorial Biosynthesis of 3-O-Carbamoylmaytansinol by Rational Engineering of the Tailoring Steps of Ansamitocins.

Currently, most maytansine-containing antibody-drug conjugates (ADCs) in clinical trials are prepared with DM1 or DM4, which in turn is synthesized mainly from ansamitocin P-3 (AP-3), a bacterial maytansinoid, isolated from Actinosynnema pretiosum. However, due to the high self-toxicity of AP-3 to A. pretiosum, the yield of AP-3 has been difficult to improve. Herein, a new maytansinoid with much lower self-toxicity to A. pretiosum, 3-O-carbamoylmaytansinol (CAM, 3), was designed and generated by introducing the 3-O-carbamoyltransferase gene asc21b together with the N-methyltransferase genes from exogenous maytansinoid gene clusters into the 3-O-acyltransferase gene (asm19) deleted mutant HGF052. Meanwhile, two new shunt products, 20-O-demethyl-19-dechloro-N-demethyl-4,5-desepoxy-CAM (4) and 20-O-demethyl-N-demethyl-4,5-desepoxy-CAM (5) were identified from the recombinant strain. Furthermore, by screening of liquid fermentation media, overexpression of bottleneck tailoring enzymes and the pathway-specific activator, the titer of CAM reached 498 mg/L in the engineered strain. Since the 3-O-carbamoyl group of CAM can be removed by chemical cleavage as AP-3 to produce maytansinol, our work suggests that CAM may be a promising alternative to AP-3 in the future development of ADCs.