Digital polymerase chain reaction(dPCR)is a PCR technology that realizes accurate quantification of single-copy nucleic acid molecules by dividing the reaction system into tens of thousands of independent PCR reaction units for single-molecule-level amplification and integrating Poisson distribution.Due to its single-copy sensitivity and accurate quantification without the need of standard curves,dPCR has been widely used in disease diagnosis.By introducing technologies such as stepped emulsification and three-dimensional imaging,dPCR has been greatly improved in terms of accuracy,multiplexability and turnaround time,significantly enhancing its performance in clinical disease diagnosis.Based on this,this paper traced the technological development history of dPCR,gave an overview of its application in detection of tumors,infections and other diseases,and further discussed the challenges and opportunities of the development of dPCR,with the aim of providing a reference for the development and utilization of dPCR in the future,and promoting the high-quality development of molecular technology in clinical testing.

Eighteen compounds were isolated from the methanol extract of the fruits of Litsea cubeba by silica gel, ODS, Sephadex LH-20 column chromatography, semi-preparative RP-HPLC, chiral HPLC and recrystallization. Their structures were elucidated by spectroscopic analyses and by comparison with reported spectroscopic data and physicochemical properties, and the absolute configurations of the enantiomers were established by experimental and calculated electronic circular dichroism spectra. These compounds were identified as (+)-(R)-4-hydroxypiperitenone (1a), (-)-(S)-4-hydroxypiperitenone (1b), (3S,4S,6R)-3,6-dihydroxy-1-menthene (2), (4S,5R)-4-hydroxy-5-isopropyl-2-methylcyclohex-2-en-1-one (3), (R)-6-hydroxy-3-(2-hydroxypropan-2-yl)-6-methylcyclohex-2-enone (4), (4S,6R)-4-hydroxy-6-isopropyl-3-methylcyclohex-2-enone (5), (1R,3S,4R)-3-hydroxy isopulegol (6), subamone (7), (6S)-3,7-dimethyl-7-hydroxy-2(Z)-octen-6-olide (8), (6S)-6,7-dihydroxy-3,7-dimethyloct-2(Z)-enoate (9), holostylactone (10), sesamin (11), dimethylmatairesinol (12), p-hydroxybenzoylcarbinol (13), syringaldehyde (14), p-hydroxybenzaldehyde (15), 4-hydroxy-3-methoxybenzaldehyde (16), 5,4ʹ-dihydroxy-7-methoxyflavone (17). Among them, compounds 1a and 1b were a pair of new monoterpenoid enantiomers, 8 and 9 were new natural products, 2-7, 10, 11 and 17 were isolated from Litsea genus for the first time. The in vitro anti-inflammatory effects of compounds 1-17 were evaluated using lipopolysaccharide-stimulated RAW264.7 cells, the results showed that compound 14 exhibited significant anti-inflammatory activity with NO inhibitory rate of 66.27% at a concentration of 40 μmol·L^-1.

Glycosylation is one of the most important reactions in living organisms as it results in the formation of glycoconjugates with diverse biological functions. Sugar nucleotides are structurally composed of sugar and nucleoside diphosphate or monophosphate, which are widespread within a variety of biological cells. As glycosyl donors for the transglycosyl reactions catalyzed by Leloir-type glycosyltransferases, sugar nucleotides are essential for the synthesis of glycans and glycoconjugates. However, high costs and limited availability of nucleotide sugars prevent applications of biocatalytic cascades on an industrial scale. Therefore, attentions on synthetic strategies of sugar nucleotides have been increasing to achieve their wide applications in various fields. The 9 common sugar nucleotides in mammals have been fully studied with large-scale synthesis through chemical, enzymatic (chemo-enzymatic) and cell factory strategies. In addition to common sugar nucleotides, many rare sugar nucleotides are present in plants and bacteria. Although unnatural sugar nucleotides cannot be synthesized in organisms, they have great potential in research as substrates for glycosyltransferases in carbohydrate synthesis, as enzyme inhibitors in biochemical studies, and as components of glycoconjugate biosynthesis. Therefore, increasing attention has been paid to explore the efficient synthesis of unnatural sugar nucleotides. Currently, strategies for chemical synthesis of sugar nucleotides have been greatly improved, such as the use of effective catalysts for forming pyrophosphate bonds and the development of entirely new synthesis protocols. Multiple sugar nucleotides, especially unnatural sugar nucleotides, are synthesized chemically. However, chemical synthesis requires tedious protection and deprotection steps, resulting in complex steps, high cost and low yield. In contrast, enzymatic (chemo-enzymatic) and cell factory methods have significant advantages such as high yield, easy operation and easy process scale-up in the preparation of sugar nucleotides. Hence, they are prominent strategies for sugar nucleotide preparation. Herein, the biosynthesis and application of sugar nucleotides are reviewed, mainly focusing on the 9 sugar nucleotides common in mammals. The early strategies for enzymatic synthesis of sugar nucleotides generally used de novo synthesis pathway. With the discoveries of enzymes involved in salvage pathway of sugar nucleotide synthesis and the development of one-pot multienzyme (OPME) method, the synthesis of sugar nucleotides was greatly simplified. Cell factory method employs the microbial living cells as a “processing plant” by engineering their metabolic pathways through genetic engineering technology. The cell factory method has high yield, and has been applied for efficient synthesis of several sugar nucleotides. Moreover, the strategy of gram-scale synthesis of multiple rare sugar nucleotides by cascade reactions from common sugar nucleotides using sugar nucleotides synthases cloned from different sources was illustrated. In recent years, the synthesis cost of sugar nucleotides has been further reduced through various ways, such as regeneration of nucleotides, regeneration of organic cofactors, and application of immobilized enzyme technology. Furthermore, through the continuous improvement of sugar nucleotide purification process, the use of high concentration of multi-enzyme cascade and rapid non-chromatographic purification process, the synthesis of multiple sugar nucleotides and their derivatives from monosaccharides was achieved, which gradually broke the limitations of the existing strategy. With the efficient synthesis of sugar nucleotides, their applications in various fields have been increasingly explored, including the synthesis of glycans and glycoconjugates, biochemical characterization of glycosyltransferases and bioorthogonal labeling strategies, which are of great significance to the research of biochemistry, glycobiology and the development of related pharmaceutical products.

RNA editing, an essential post-transcriptional reaction occurring in double-stranded RNA (dsRNA), generates informational diversity in the transcriptome and proteome. In mammals, the main type of RNA editing is the conversion of adenosine to inosine (A-to-I), processed by adenosine deaminases acting on the RNAs (ADARs) family, and interpreted as guanosine during nucleotide base-pairing. It has been reported that millions of nucleotide sites in human transcriptome undergo A-to-I editing events, catalyzed by the primarily responsible enzyme, ADAR1. In hematological malignancies including myeloid/lymphocytic leukemia and multiple myeloma, dysregulation of ADAR1 directly impacts the A-to-I editing states occurring in coding regions, non-coding regions, and immature miRNA precursors. Subsequently, aberrant A-to-I editing states result in altered molecular events, such as protein-coding sequence changes, intron retention, alternative splicing, and miRNA biogenesis inhibition. As a vital factor of the generation and stemness maintenance in leukemia stem cells (LSCs), disordered RNA editing drives the chaos of molecular regulatory network and ultimately promotes the cell proliferation, apoptosis inhibition and drug resistance. At present, novel drugs designed to target RNA editing(e.g., rebecsinib) are under development and have achieved outstanding results in animal experiments. Compared with traditional antitumor drugs, epigenetic antitumor drugs are expected to overcome the shackle of drug resistance and recurrence in hematological malignancies, and provide new treatment options for patients. This review summarized the recent advances in the regulation mechanism of ADAR1-mediated RNA editing events in hematologic malignancies, and further discussed the medical potential and clinical application of ADAR1.

Objective:To explore effect of oleanolic acid on allergic rhinitis(AR)and its potential mechanism.Methods:Peripheral blood mononuclear cells(PBMCs)were isolated by density gradient centrifugation.Real-time quantitative PCR was used to detect expressions of Foxp3,IL-17A,Beclin1,and RORγt mRNA in nasal mucosa;flow cytometry was employed to assess proportion of Treg and Th17 cells in PBMCs;Western blot was utilized to determine expressions of RORγt,LC3-Ⅰ,LC3-Ⅱ,Beclin1,and P62 proteins in nasal mucosal.Mice were randomly divided into Control,ovalbumin(OVA),L-oleanolic acid,H-oleanolic acid,DSGC,3-MA and H-oleanolic acid+Rapa groups.Histological changes were observed by HE staining and Periodate Schiff(PAS)staining.Serological changes,expressions of IL-17A,IL-10,eosinophilic cationic protein(ECP)and anti-OVA-specific antibodies were detected by ELISA.Results:AR patients had Th17/Treg imbalance and activated autophagy.Oleanolic acid restored Th17/Treg balance and inhibited autophagy in vitro.In vivo experiments demonstrated that oleanolic acid inhibited OVA-induced allergic nasal symptoms and activation of autophagy pathway,which was same as regulation of 3-MA,while Rapa could weaken effects of high dose of oleanolic acid.Moreover,oleanolic acid reduced infiltration of different inflammatory cells of nasal lavage fluid,prevented damages to epithelial cells,and improved nasal mucosal thickness and mucus secretion.Oleanolic acid regulated balance of mouse Th17/Treg-associated cytokines expressions.Conclusion:Oleanolic acid can be used to treat AR,whose effect is realized through inhibiting autophagy to regulate Th17/Treg balance.

HDAC(histone deacetylase)is a class of epigenetic modifying enzymes that can deacetylate proteins by altering the acetylation status of histones in the nucleus,regulating promoter activation levels,and thereby affecting downstream gene expression.However,expression changes of HDACs during endo-thelial differentiation are still unclear.This study used a three-stage method to induce human induced pluripotent stem cells(hiPSCs)to differentiate into endothelial cells,and qRT-PCR was used to detect the expression changes of class I HDAC(HDAC1,2)and class Ⅱ HDAC(HDAC4,5)genes.It was found that HDAC5 exhibits significant expression changes during endothelial differentiation.It is downreg-ulated by 90％during the mesodermal differentiation stage(P＜0.01),upregulated by 3.7-fold during the vascular precursor stage(P＜0.01),and subsequently downregulated by 70％during the late stage of endothelial differentiation(P＜0.01).Immunoblotting experiments further confirmed that HDAC5 under-goes periodic expression changes during endothelial differentiation.Mechanistic studies have shown that HDAC5 downregulation during the differentiation stage of the mesoderm is mediated by Wnt signaling.CHIR99021 treatment and overexpression of Wnt3a can activate the Wnt signaling pathway,leading to HDAC5 downregulation.Inhibiting the Wnt signaling pathway through IWP-2 promotes the recovery of HDAC5 expression.In addition,it was found that HDAC5 is mainly localized in the nucleus,and IWP-2 restores HDAC5 expression,but it remains in the cytoplasm.Further research suggests that downregu-lation of HDAC5 during mesodermal differentiation may contribute to the expression of the mesodermal marker BraT.Treatment with the HDAC inhibitor BML210 can promote early mesodermal differentiation,interfere with endothelial differentiation of vascular precursor cells,and enhance late-stage endothelial differentiation.In conclusion,HDAC5 displays a stage-specific expression during endothelial differentia-tion,and Wnt signaling activation is the main mechanism regulating the downregulation of HDAC5 during the mesoderm stage.

Objective:To understand the serological characteristics of irregular antibodies in pregnant women and explore their clinical significance.Methods:From January 2017 to March 2022,151 471 pregnant women in Women and Children's Hospital of Chongqing Medical University were enrolled in this study,microcolumn gel card test was used for irregular antibody screening,and antibody specificity identification was further performed in some antibody-positive subjects.Results:The positive rate of irregular antibody screening in the enrolled pregnant women was 0.91％(1 375/151 471),0.23％(355/151 471)was detected in the first trimester,0.05％(71/151 471)in the second trimester,and 0.63％(949/151 471)in the third trimester.The positive rate of irregular antibody screening in the third trimester was significantly higher than that in the first and second trimester,and a significant increase in the number of positive cases was found in the third trimester than that in the second trimester.The analysis of agglutination intensity of 1 375 irregular antibody screening positive results showed that the weakly positive agglutination intensity accounted for 50.11％(689/1 375),which was the highest,the suspicious positive was 18.69％(257/1 375),and the positive was 31.20％(429/1 375).The significant difference in distribution of agglutination intensity was not observed between the first trimester group and the second trimester group,however,in the third trimester,the proportion of suspicious positive and weakly positive was lower than the first trimester,while,the proportion of positive was higher than the first trimester,and the difference was statistically significant(P＜0.001).Among the irregular antibody screening positive pregnant women,the proportion of pregnant women with pregnancy number ≥ 2 was significantly higher than that with pregnancy≤1.Among 60 pregnant women who underwent antibody identification,the distributions of the antibodies were as follows:Rh blood group system accounted for 23.33％(14/60),Lewis system 43.33％(26/60),Kidd system 3.33％(2/60),MNS system 16.67％(10/60),P1PK system 1.67％(1/60),autoantibodies 1.67％(1/60),and 4 cases was unable to identify(6.67％,4/60).Among specific antibodies,the anti-Lea was the most common(30.00％),followed by anti-E(16.67％)and anti-M(16.67％).Conclusion:The differences of irregular antibody serological characteristics exist in pregnant women from different regions with different genetic backgrounds,understanding the characteristics of irregular antibody in local pregnant women is of great significance for ensuring transfusion safety in pregnant women and preventing hemolytic disease of newborn.

The detection of cancer markers is of great significance for the early diagnosis and subsequent treatment of cancer.However,the existing traditional detection methods have some limitations,especially in the early stages of cancer,thus is often difficult to detect in a timely and accurate manner.As an efficient detection technique,electrochemical sensors can meet the requirement of accurate detection of various cancer markers,provide strong support for early diagnosis of cancer,and have broad application prospects.MXene is a new two-dimensional material,which is widely used in electrochemical sensors because of its unique properties such as high electron transfer ability,high conductivity,large specific surface area,good biocompatibility and hydrophilicity and abundant surface chemical groups,etc.This paper reviewed the applications of electrochemical biosensors based on MXene composites in cancer marker detection in recent years,introduced the function of MXene in electrochemical biosensor,and discussed challenges and future development trends of MXene in the early diagnosis of cancer,aiming to provide reference for early detection of cancer.

Objective To investigate the incidence rate,clinical characteristics,and prognosis of neonatal stroke in Shenzhen,China.Methods Led by Shenzhen Children's Hospital,the Shenzhen Neonatal Data Collaboration Network organized 21 institutions to collect 36 cases of neonatal stroke from January 2020 to December 2022.The incidence,clinical characteristics,treatment,and prognosis of neonatal stroke in Shenzhen were analyzed.Results The incidence rate of neonatal stroke in 21 hospitals from 2020 to 2022 was 1/15 137,1/6 060,and 1/7 704,respectively.Ischemic stroke accounted for 75％(27/36);boys accounted for 64％(23/36).Among the 36 neonates,31(86％)had disease onset within 3 days after birth,and 19(53％)had convulsion as the initial presentation.Cerebral MRI showed that 22 neonates(61％)had left cerebral infarction and 13(36％)had basal ganglia infarction.Magnetic resonance angiography was performed for 12 neonates,among whom 9(75％)had involvement of the middle cerebral artery.Electroencephalography was performed for 29 neonates,with sharp waves in 21 neonates(72％)and seizures in 10 neonates(34％).Symptomatic/supportive treatment varied across different hospitals.Neonatal Behavioral Neurological Assessment was performed for 12 neonates(33％,12/36),with a mean score of(32±4)points.The prognosis of 27 neonates was followed up to around 12 months of age,with 44％(12/27)of the neonates having a good prognosis.Conclusions Ischemic stroke is the main type of neonatal stroke,often with convulsions as the initial presentation,involvement of the middle cerebral artery,sharp waves on electroencephalography,and a relatively low neurodevelopment score.Symptomatic/supportive treatment is the main treatment method,and some neonates tend to have a poor prognosis.

Objective To investigate the dosimetric effects of different calculation grid size(CGS)in helical tomotherapy(HT)planning system on stereotactic body radiation therapy(SBRT)for non-small cell lung cancer(NSCLC).Methods Nine NSCLC patients receiving radiation therapy for the first time at some hospital from March 2019 to December 2022 were selected as the subjects.SBRT planning was carried out through the HT system with three different CGS plans(Fine,Normal,and Coarse)and the same pitch,modulation factor(MF)and optimization conditions,and the target area indexes of the three CGS plans were compared including conformity index(CI),homogeneity index(HI),dosimetric parameters of the organ at risk(OAR),point dose verification pass rate,treatment time,number of monitor units and Sinograms.SPSS 22.0 was used for statistical analysis.Results For target area HI,there weres significant differences between CGS Fine plan and Coarse plan and between CGS Normal plan and Coarse plan(P＜0.05),while no statistical differences were found between CGS Fine plan and Normal plan(P＞0.05).For target area CI,there were significant differences between CGS Fine plan and Coarse plan(P＜0.05),while no statistical differences were found between CGS Fine plan and Normal plan and between CGS Normal plan and Coarse plan(P＞0.05).For OAR dosimetric parameters,CGS Fine plan and Coarse plan had significant differences in heart Dmax and Dmean,esophageal Dmax and Dmean,V5,V20,V30 and Dmean of the whole lung and affected lung,V5 and Dmax of the affected lung and heart V10 and V30(P＜0.05),CGS Normal plan and Coarse plan had obvious differences in esophageal Dmax(P＜0.05),and the remained dosimetric parameters were not statistically significant(P＞0.05).Fine,Normal and Coarse plans had the point dose verifica-tion pass rates being 0.96％,1.50％and 1.77％,respectively.In terms of treatment time and number of monitor units,there were significant differences between Fine plan and Coarse plan(P＜0.05)while no statistical differences were found between Fine and Normal plans and between Normal and Coarse plans(P＞0.05).Sinograms analyses showed Fine plan had evenly distributed segment color gradient,Coarse plan had areas of very dark and very light color gradients and Normal plan was somewhere in between.Conclusion Low CGS has to be used as much as possible to obtain accurate dose distribution during SBRT planning for NSCLC patients,which contributes to the execution of the radiation therapy plan and the prevention of ad-verse effects.[Chinese Medical Equipment Journal,2024,45(2):52-57]