[Site-directed mutagenesis enhances the activity of dextranase from Arthrobacter oxidans KQ11].

Dextranase is an enzyme that specifically hydrolyzes the α-1, 6 glucoside bond. In order to improve the activity of dextranase from Arthrobacter oxidans KQ11, site-directed mutagenesis was used to modify the amino acids involved in the "tunnel-like binding site". A saturating mutation at position 507 was carried out on this basis. The mutant enzymes A356G, S357W, W507Y, and W507F with improved enzyme activities and catalytic efficiency were successfully obtained. Compared with wild type (WT), W507Y showed the specific activity increasing by 3.00 times, the kcat value increasing by 3.62 times, the Km value decreasing by 54%, and the catalytic efficiency (kcat/Km) increasing by 8.98 times. The three-dimensional structure analysis showed that the increase of the number of hydrogen bonds and the distance between "tunnel-like binding sites" were important factors affecting enzyme activity. Compared with WT, W507Y had a shortened distance from the residues on the other side of the "tunnel-like binding site", which made it easier to generate hydrogen binding forces. Accordingly, the substrate hydrolysis and product efflux were accelerated, which dramatically increased the enzyme activity and catalytic efficiency.

Clinical evaluation of enhanced recovery versus conventional care in the perioperative period for intradural extramedullary spinal tumors: a study protocol for a multicenter, randomized controlled trial.

BACKGROUND: This randomized clinical trial protocol aimed to investigate the comparative efficacy of an enhanced recovery after surgery (ERAS) protocol versus traditional perioperative care programs in patients with intradural extramedullary spinal tumors. METHODS: The study included 180 patients aged 18-80 years, who were randomly assigned to two groups: Group A receiving traditional perioperative care and Group B receiving accelerated rehabilitation perioperative care. The nurse responsible for patient care was informed of the group assignment, but the patients themselves remained blinded to the intervention. The primary outcome measure was the Karnofsky Performance Scale score, which assessed functional status. The secondary outcomes included the Japanese Orthopedic Association Scale, Numeric Pain Rating Scale, length of postoperative hospital stay, duration of urethral catheterization, patient satisfaction questionnaire, and complication rates. Follow-up assessments were conducted telephonically 1 month, 3 months, and 6 months after the surgery. DISCUSSION: This study protocol provided a structured approach to assess the potential benefits of ERAS during the perioperative period for patients with intradural extramedullary tumors, aiming to improve patient outcomes and overall care efficiency. TRIAL REGISTRATION: This study has been registered with the China Clinical Trials Registry (Project No: ChiCTR2200063347). Registered on September 5 2022.

Risk Factors for Post-Stroke Depression Following the Lifting of COVID-19 Restrictions.

Purpose: Research on post-stroke depression (PSD) following the lifting of coronavirus disease 2019 (COVID-19) restrictions remains sparse. This study aimed to investigate the factors associated with PSD after the easing of COVID-19 restriction measures. Patients and Methods: This cross-sectional study was conducted with 947 stroke patients (cerebral hemorrhage and cerebral infarction) meeting the inclusion criteria. Participants completed a demographic questionnaire and the Patient Health Questionnaire-9 (PHQ-9). Additionally, data were collected on C-reactive protein (CRP), homocysteine (Hcy), modified Rankin Scale (mRS), stroke site, National Institutes of Health Stroke Scale (NIHSS), thyroid-stimulating hormone (TSH), and the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification. This study assessed correlations between these indices and PSD. Results: Stroke patients with a PHQ-9 score ≥5 were identified as having PSD, with a prevalence rate of 14.15%. No significant correlation was found between previous COVID-19 infection and PSD. However, multiple regression analysis revealed associations between PSD and the following factors: TSH (OR: 0.87, 95% CI: 0.76-1), CRP levels (OR: 1.01, 95% CI: 1-1.02), family history of stroke (OR: 4.25, 95% CI: 1.66-10.88), migraine history (OR: 8.63, 95% CI: 2.49-29.85), and shorter sleep duration (OR: 0.6, 95% CI: 0.51-0.71) (all P < 0.05). Conclusion: CRP, family history of stroke, migraine, sleep duration, and TSH are identified as independent risk factors for PSD following the lifting of COVID-19 restrictions.

Strain-induced ferroelectric polarization reversal without undergoing geometric inversion in blue SiSe monolayer.

Ferroelectricity in two-dimensional (2D) systems generally arises from phonons and has been widely investigated. On the contrary, electronic ferroelectricity in 2D systems has been rarely studied. Using first-principles calculations, the ferroelectric behavior of the buckled blue SiSe monolayer under strain are explored. It is found that the direction of the out-of-plane ferroelectric polarization can be reversed by applying an in-plane strain. And such polarization switching is realized without undergoing geometric inversion. Besides, the strain-triggered polarization reversal emerges in both biaxial and uniaxial strain cases, indicating it is an intrinsic feature of such a system. Further analysis shows that the polarization switching is the result of the reversal of the magnitudes of the positive and negative charge center vectors. And the variation of buckling is found to play an important role, which results in the switch. Moreover, a non-monotonic variation of band gap with strain is revealed. Our findings throws light on the investigation of novel electronic ferroelectric systems.

Biosynthesis of α-keto acids and resolution of chiral amino acids by l-amino acid deaminases from Proteus mirabilis.

Chiral amino acids and their deamination products, α-keto acids, have important applications in food, medicine, and fine chemicals. In this study, two l-amino acid deaminase genes from Proteus mirabilis, PM473 of type Ⅰ and PM471 of type Ⅱ were cloned and expressed in Escherichia coli respectively, expected to achieve the chiral separation of amino acids. Extensive substrate preference testing showed that both deaminases had catalytic effects on the d-amino acid component of the D, l-amino acids, and PM473 has a wider catalytic range for amino acids. When D, L-Cys was used as the substrate, all L-Cys components and 75.1 % of D-Cys were converted to mercapto pyruvate, and the remaining D-Cys was a single chiral enantiomer. Molecular docking analysis showed that the interaction between the substrate and the key residues affected the stereoselectivity of enzymes. The compatibility of hydrophobicity between the binding pocket and substrate may be the basic factor that affects the substrate selectivity. This work provides an alternative method for the production of α-keto acids and the resolution of chiral amino acids.

Sliding ferroelectricity and the moiré effect in Janus bilayer MoSSe.

Two-dimensional van der Waals layered materials have attracted extensive attention in the field of low-dimensional ferroelectricity, on account of their readily delaminated structure and high-density information storage advantages. Here, we report the sliding ferroelectricity and moiré effects on the ferroelectricity in Janus bilayer MoSSe based on first-principles calculations. We focus on the changes of in-plane and out-of-plane polarizations due to sliding, and the calculations demonstrate that the in-plane and out-of-plane polarizations can be switched simultaneously by sliding. In addition, in moiré-twisted bilayer MoSSe, the complex stacking pattern and significant interlayer distance suppress the interlayer charge transfer, and the ferroelectric polarization is effectively suppressed. The polarization in the large-angle twisted structure is small but its direction can be adjusted by changing the twist angle. Our results emphasize the importance of low-dimensional ferroelectrics in van der Waals structures and pave a way for the search of sliding ferroelectric materials, as well as enriching the research on the ferroelectricity of large-angle twisted structures.

Vaccination against SARS-CoV-2 contributed to reducing the prevalence of depression in Chinese adults - A cross-sectional study.

BACKGROUND: SARS-CoV-2 vaccination has been reported to improve mental health. However, few relevant data were collected in China. The study aimed to evaluate the impact of SARS-CoV-2 vaccination on the risk of depression in China and risk factors contributing to depression. METHODS: This is a cross-sectional study carried out from May 2020 to July 2021. Participants were widely recruited in China to participate in the survey using an online questionnaire including Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, Athens Insomnia Scale-8.After exclusion of 105 ineligible questionnaires, 9452 participants were included in our final analysis. Chi-square test and Multivariable logistic regression analysis were used to analyze data. RESULTS: Of the 9452 participants, 7207 were vaccinated. Our results showed that the prevalence of depression decreased significantly after vaccination (56.1 % for unvaccinated participants vs. 19.7 % for vaccinated participants). The prevalence of mild, moderate and severe depression was also significantly lower in the vaccinated participants than in the unvaccinated participants (14.8 % vs 29.0 %, 2.8 % vs 13.3 %, 2.0 % vs 13.8 %, respectively). Besides, among vaccinated participants, male and aged participants had a lower chance of developing depression (AOR = 1.34; AOR = 0.63; AOR = 0.5, respectively). In addition, although with vaccination, participants with anxiety and insomnia were more likely to suffer from depression (AOR = 29.2; AOR = 11.89). LIMITATIONS: The study was a cross-sectional survey. The numbers of participants differed much in the two groups. CONCLUSIONS: The present study confirmed that SARS-CoV-2 vaccination contributed to reducing the prevalence of depression in Chinese adults. Moreover, vaccinated men and older adult participants had less prevalence of depression.

Modification of the Loop Region Near the Substrate Tunnel to Alter the Hydrolytic Process of Dextranase.

Dextranases are hydrolases that exclusively catalyze the disruption of α-1,6 glycosidic bonds. A series of variant enzymes were obtained by comparing the sequences of dextranases from different sources and introducing sequence substitutions. A correlation was found between the number of amino acids in the 397-401 region and the hydrolytic process. When there were no more than 5 amino acids in the 397-401 region, the enzyme first hydrolyzed the dextran T70 to a low molecular weight dextran with a molecular weight of about 5000, then IMOs1 appeared in the system if the degradation continued, showing a clear sequential relationship. And when there are more than 5 amino acids in the 397-401 region, IMOs were produced at the beginning of hydrolysis and continue to increase throughout the hydrolytic process. At the same time, we investigated the enzymatic properties of the variants and found that the hydrolytic rate of A-Ca was 11 times higher than that of the original enzyme. The proportion of IMOs produced by A-Ca was 80.68%, which was nearly10% higher than the original enzyme, providing a new enzyme for the industrial preparation of IMOs.

Mechanism analysis of a novel natural cationic modified dextran flocculant and its application in the treatment of blue algal blooms.

Blue algae, a type of harmful microalgae, are responsible for causing harmful algal blooms that result in severe environmental issues. To address this problem, a biopolysaccharide-based flocculant was developed for treating blue algae blooms. This flocculant was created by modifying high molecular weight dextran using the natural cationic monomer betaine (Dex-Bet), making it environmentally friendly. Various techniques were used to characterize the prepared Dex-Bet flocculant, including infrared spectroscopy (FTIR), nuclear magnetic resonance hydrogen spectroscopy (1H NMR), X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The effectiveness of the Dex-Bet flocculant was evaluated using kaolin-simulated wastewater. The results showed that the treated supernatant had a transmittance of up to 98.25 %. Zeta potential analysis revealed that the main mechanisms of flocculation were charge neutralization, charge patching, and adsorption bridging. The application of Dex-Bet in treating blue-green algae resulted in a maximum removal rate of 98.2 %. This study provides a potential flocculant for blue algae bloom treatment.

Application effect of diversified health-promoting models on rehabilitation exercises for cervical spondylotic myelopathy.

BACKGROUND: With improving living standards, the incidence of cervical spondylotic myelopathy (CSM) has become increasingly high. OBJECTIVE: The study aims to explore the effect of diversified health-promoting models on rehabilitation exercises in patients with CSM after an operation. METHOD: This was a randomized controlled trial, wherein 107 patients with CSM treated by neurosurgery were selected as the subjects. Of those, 52 patients in the control group adopted the conventional health-promoting model, while the remaining 55 patients in the intervention group adopted diversified health-promoting models. The effect of rehabilitation exercises in the two groups was evaluated according to the self-efficacy rehabilitation outcome scale, grip strength measurement of the affected limb, and Barthel index. RESULTS: At Day 3 post-operation and before discharge, the self-efficacy management of rehabilitation exercises in the intervention group was better than that of the control group (P< 0.05). The grip strength measurement of the affected limb, Japanese Orthopedic Association score of the cervical vertebra, and Barthel index of the two groups at Day 3 post-operation were lower than before the intervention and were not statistically significant (P> 0.05). However, these three items before discharge were improved when compared with those of before intervention and were statistically significant (P< 0.05). CONCLUSION: Postoperative rehabilitation exercises guided by the diversified health-promoting models for patients with CSM can improve the patients' self-efficacy management ability in rehabilitation exercises, help improve grip strength, and promote the recovery of cervical vertebra function, thereby improving the patients' quality of life.

Case presentation of Campylobacter rectus leading to pneumonia and literature review.

Pneumonia caused by Campylobacter rectus is very rare. Herein, we describe the treatment course and experiences of a patient with pneumonia caused by Campylobacter rectus. A 64-year-old woman with intermittent hemoptysis and part lung necrosis indicated by radiography was admitted to our hospital on March 15, 2021. After admission, a CT (Computer tomography)-guided percutaneous lung biopsy was identified as Campylobacter rectus positive by bacterial culture and metagenomic sequencing. The hemoptysis resolved, and the lesions in the right lower lung were gradually absorbed after treatment with anti-Campylobacter rectus drugs. In cases of pneumonia which unresolved by initial therapy and associated with more severe oral hygiene problems, the possibility of infection with oral pathogens (eg, Campylobacter rectus) should be considered. This case suggests that bacterial culture and metagenomic sequencing of the diseased tissue, particularly anaerobic culture, helps to clarify the etiological diagnosis.

Biosynthesis, Characterization, and Bioactivity of L-Alanyl-L-tyrosine in Promoting Melanin Synthesis.

L-Alanyl-L-tyrosine (L-Ala-Tyr) is a dipeptide formed by the condensation of L-alanine methyl ester and L-tyrosine. After entering the body, it can be rapidly broken down to release tyrosine. In this study, L-Ala-Tyr was successfully prepared by using α-ester acyltransferase as biocatalyst and alanine methyl ester (L-Ala-OMe) and tyrosine (L-Tyr) as acyl donor and nucleophile, respectively. The dipeptide yield was increased from 15 to 50% by optimizing the conditions: boric acid-borax (0.2 mol/L), 30°C, pH 9.5, 2:1 acyl donor to nucleophile ratio, DES (ChCl/urea), and 15%(v/v) water content. The catalytic product is then isolated and purified. The structure of the product was identified by high-performance liquid chromatography, mass spectrometry, proton nuclear magnetic resonance, and carbon spectroscopy. Its biological activity was preliminarily determined by the B16-F10 mouse melanoma cell model. The results showed that the purity of L-Ala-Tyr prepared by the separation and purification method of this study was 96.8%, and the mass spectrometry and nuclear magnetic resonance spectroscopy showed that the structure of the peptide was consistent with the expected structure. In addition, the preliminary physiological activity identification results show that L-Ala-Tyr has no toxic effect on cells in the concentration range of 100-800 µmol·L-1, and at the optimal concentration, compared with the positive control 8-methoxypsoralen, it can promote the production of melanin.

Bibliometric Analysis of Global Trends in Research on Seasonal Variations in Gut Microbiota from 2012 to 2022.

Seasons are the important influencing factor for gut microbiota, which in turn affects the ecology and evolution of the host. The seasonal variation in gut microbiota has increasingly attracted the attention of researchers and professionals worldwide. However, studies of seasonal variations in gut microbiota have not been systematically analyzed by bibliometrics or visual analysis. This study is based on 271 publications from 2012 to 2022 in the Web of Science Core Collection database (WOSCC) to analyze hot spots and trends in this field. The collaborations between different countries, institutions, authors, journals, and keywords were bibliometrically analyzed using Excel, CiteSpace (Version 6.2. R4), and VOSviewer (version 1.6.19) software. The number of publications has been increasing rapidly and shows a general upward trend. China and the Chinese Academy of Sciences are the country and institution contributing the most, respectively. The research hotspots and trends mainly include the diversity of gut microbiota communities in different seasons, the relationship between diet and gut microbiota in seasonal changes, and the relationship between gut microbiota and evolutionary adaptation in seasonal changes. This is the first bibliometric and visualization analysis of seasonal variations in gut microbiota, which may advance this field and lay the foundation for future research.

Review on recent advances in the properties, production and applications of microbial dextranases.

Dextranase is a type of hydrolase that is responsible for catalyzing the breakdown of high-molecular-weight dextran into low-molecular-weight polysaccharides. This process is called dextranolysis. A select group of bacteria and fungi, including yeasts and likely certain complex eukaryotes, produce dextranase enzymes as extracellular enzymes that are released into the environment. These enzymes join dextran's α-1,6 glycosidic bonds to make glucose, exodextranases, or isomalto-oligosaccharides (endodextranases). Dextranase is an enzyme that has a wide variety of applications, some of which include the sugar business, the production of human plasma replacements, the treatment of dental plaque and its protection, and the creation of human plasma replacements. Because of this, the quantity of studies carried out on worldwide has steadily increased over the course of the past couple of decades. The major focus of this study is on the most current advancements in the production, administration, and properties of microbial dextranases. This will be done throughout the entirety of the review.

Rational design of a self-assembly promoting fusion domain enhances high molecular weight levan synthesis by levansucrase SacB.

The catalytic product of levansucrase from Bacillus subtilis (SacB) is mainly composed of 10 % high molecular weight levan (HMW, ~2000 kDa) and 90 % low molecular weight levan (LMW, ~7000 Da). In order to achieve efficient production of food hydrocolloid, high molecular weight levan (HMW), with the help of molecular dynamics simulation software, a protein self-assembly element, Dex-GBD, was found and fused with the C-terminus of SacB to construct a novel fusion enzyme, SacB-GBD. The product distribution of SacB-GBD was reversed compared with SacB, and the proportion of HMW in the total polysaccharide was significantly increased to >95 %. We then confirmed that the self-assembly was responsible for the reversal of the SacB-GBD product distribution by the simultaneous modulation of SacB-GBD particle size and product distribution by SDS. The hydrophobic effect may be the main driver of self-assembly as analyzed by molecular simulations and hydrophobicity determination. Our study provides an enzyme source for the industrial production of HMW and provides a new theoretical basis for guiding the molecular modification of levansucrase towards the size of the catalytic product.

Evaluation of root position during orthodontic treatment via multiple intraoral scans with automated registration technology.

INTRODUCTION: This study aimed to introduce a method for dynamically monitoring root position with intraoral scans using automated crown registration and root segmentation with artificial intelligence technology and to evaluate its accuracy using a novel semiautomatic root apical distance measurement procedure. METHODS: The sample consisted of 412 teeth from 16 patients whose intraoral scans and cone-beam computed tomography (CBCT) were obtained before and after treatment. Crowns from intraoral scans and roots segmented from CBCT with artificial intelligence technology before treatment were registered, integrated, and divided into individual teeth. With an automated registration program, the virtual root was constructed by crown registration before and after treatment. The distance deviation of the root position at the apex between the virtual root and the actual root, which served as a control, was measured and decomposed into the distance deviation in the mesiodistal and buccolingual directions. RESULTS: The shell deviation of crown registration between CBCT and oral scan before treatment was 0.19 ± 0.04 mm and 0.22 ± 0.04 mm in the maxilla and mandible, respectively. The apical root position distance deviations were 0.27 ± 0.12 mm in the maxilla and 0.31 ± 0.11 mm in the mandible. There was no significant difference between root position in mesiodistal and buccolingual directions. CONCLUSIONS: Applying automated crown registration and root segmentation with artificial intelligence technology in this study improved the accuracy and efficiency of monitoring root position. In addition, the innovative semiautomatic distance measurement procedure can more precisely distinguish the root position discrepancy.

Osthole relieves skin damage and inhibits chronic itch through modulation of Akt/ZO-3 pathway in atopic dermatitis.

Atopic dermatitis (AD) is the most prevalent chronic inflammatory skin condition and significantly reduces quality of life. Tight junction (TJ), which is located directly beneath the stratum corneum, maintains skin barrier function and aids in the identification of the cell's "territory". We evaluated seventeen TJ related genes to explore AD related alterations of TJ. Remarkably, we found that the expression of ZO-3, a gene that had not been linked to the development of TJ in AD, was significantly down-regulated in the skin of AD mice and patients. siRNA mediated knock-down of ZO-3 significantly decreased transepithelial electrical resistance in HaCaT cells, demonstrating that ZO-3 is essential to epidermal barrier function. In addition to ZO-3 downregulation, protein kinase B (Akt) phosphorylation was increased in the skin of AD mice. We further confirmed an inverse relationship between Akt phosphorylation and ZO-3 expression in AD using HaCaT cells and mouse model. Finally, we tested the efficacy of osthole as a treatment for AD in mice and HaCaT cells. Osthole inhibits Akt phosphorylation, and thereby enhances ZO-3 expression in mouse models of AD, resulting in greatly lessened AD associated skin damage and chronic itch, and osthole also increased the expression of ZO-3 in HaCaT cells by inhibiting the phosphorylation of Akt. Together, we established that ZO-3 is essential for the development of TJ in AD skin and HaCaT cells, and our findings provide fresh support for osthole's ability to protect ZO-3 expression and the epidermal barrier in AD.

Xp21 DNA microdeletion syndrome in a Chinese family: clinical features show retinitis pigmentosa and chronic granuloma.

Xp21 DNA microdeletion syndrome is a very rare disease characterized by retinitis pigmentosa (RP), chronic granulomatous disease (CGD), and McLeod syndrome (MLS). Due to the complex and diverse clinical manifestations, early diagnosis remains a challenge for many physicians. In this study, for the purpose of determining the pathogenic gene variants and definitive diagnosis in a patient medically backgrounded with RP and CGD from a normal Chinese family, whole-exome sequencing (WES) was performed in this proband and copy number variation (CNV) was further verified in other family members by qPCR. A genetic evaluation revealed that the short arm of the X chromosome in the proband had a deletion CNV Xp21.1p11.4 (37431123-38186681) of approximately 0.755 Mb in size, and contained three contiguous OMIM genes as X-linked Kx blood group antigen (XK), cytochrome b-245 beta chain (CYBB), and RP GTPase regulator (RPGR). The qPCR results confirmed the copy number loss in Xp21.1p11.4 present in the proband and his unaffected mother. According to the American College of Medical Genetics and Genomics (ACMG) guidelines for the CNV interpretation, the deletion of this segment was a pathogenic variant. Our results provided evidence that CNV deletion of Xp21.1p11.4 in the short arm of the X chromosome was a pathogenic variant in such Chinese RP and CGD family, and the McLeod phenotype was not yet available. This study suggests that genetic testing is essential for a definitive diagnosis, which should better assist physicians in prediction, diagnosis, genetic counseling, and guidance for Xp21 DNA microdeletion syndrome.

Development of thermostable dextranase from Streptococcus mutans (SmdexTM) through in silico design employing B-factor and Cartesian-ΔΔG.

The thermal stability of enzymes dramatically limits their application in the industrial field. Based on the crystal structure, we conducted a semi-rational design according to the B-factor and free energy values to improve the stability of dextranase from Streptococcus mutans (SmdexTM). The B-factor values of Asn102, Asn503, Asp501 and Asp500 were the highest predicted by B-FITTER. Then Rosetta was used to simulate the saturation mutations of Asn102, Asn503, Asp501 and Asp500. The mutated amino acid was designed according to the change of acG. The results showed that the thermal stability of N102P, N102C, D500G, and D500T was improved, and the half-lives of N102P/D500G and N102P/D500T at 45 °C were increased to 3.14 times and 2.44 times, respectively. Analyzing the interaction of amino acids by using Discovery Studio 4.5, it was observed that the thermal stability of dextranase was improved due to the increase in hydrophobicity and the number of hydrogen bonds of the mutant enzyme. The catalytic efficiency of N102P/D500T was increased. Compared with the hydrolyzed products of SmdexTM, the mutant enzymes do not change the specificity of hydrolysates.