Terahertz metasurface for near-field beam conversion.

A uniform illumination over a screen is crucial for terahertz imaging. As such, conversion from a Gaussian beam to a flattop beam becomes necessary. Most of the current beam conversion techniques rely on bulky multi-lens systems for collimated input and operate in the far-field. We present a single metasurface lens to efficiently convert a quasi-Gaussian beam from the near-field region of a WR-3.4 horn antenna to a flattop beam. The design process is divided into three sections to minimize simulation time, and the conventional Gerchberg-Saxton (GS) algorithm is supplemented with the Kirchhoff-Fresnel diffraction equation. Experimental validation confirms that a flattop beam with an efficiency of 80% has been achieved at 275 GHz. Such high-efficiency conversion is desirable for practical terahertz systems and the design approach can be generally used for beam shaping in the near-field.

An all-graphdiyne electrochemiluminescence biosensor for the ultrasensitive detection of microRNA-21 based on target recycling with DNA cascade reaction for signal amplification.

Graphdiyne oxide quantum dots (GDYO QDs), as derivatives of graphdiyne (GDY), have excellent electroconductibility and luminous properties and can be applied as a new ECL emitter. Herein, an electrochemiluminescence (ECL) biosensor for miRNA-21 ultrasensitive determination is constructed based on AuNPs/GDY, GDYO QD and oligonucleotide signal amplification strategy that integrates DNA walker and hybridization chain reaction (HCR) amplification. As electrode substrate material, AuNPs/GDY can not only bond with the aptamer CP but can also enhance the conductivity of the interface. When miRNA-21 exists, the DNA walker process is initiated, and the signaling probes are introduced on the electrode surface, producing abundant double-stranded H1/H2; then, H3/H4 undergoes complementary base pairing with H1/H2 through HCR. With the increase in miRNA-21, the 3D DNA nanomachine is actively manipulated, resulting in a gradual increase in ECL signal. This ECL biosensor demonstrates outstanding performance in the determination of miRNA-21 in the linear range from 0.1 fM to 1 nM. This study offers a new sensitive idea for the clinical analysis of cancer biomarkers.

Superior performance of a graphdiyne self-powered biosensor with exonuclease III-assisted signal amplification for sensitive detection of microRNAs.

Graphdiyne (GDY) is an sp and sp2 co-hydrocarbon allotrope whose particular structure endows it with many fascinating properties, including abundant chemical bonds, high conjugation, natural pores, high carrier mobility, high conductivity and stability, etc. In this work, two-dimensional graphdiyne is prepared as an electrode substrate material coupling with an exonuclease III-assisted amplification strategy to construct a superior-performance self-powered biosensor based on enzymatic biofuel cells for highly sensitive detection of the tumour marker miRNA-21. Glucose oxidase (GOD) is first immobilized on the GDY/AuNP composite to prepare a bioconjugate. GDY/AuNP modified carbon cloth is used as an enzyme biofuel cell electrode, which is then modified with bilirubin oxidase as a biocathode. The bioconjugate binds to GOD through specific binding to the bioanode. When miRNA-21 is present, specific recognition by exonuclease III in the system results in cleavage of the capture probe, and miRNA-21 is recovered and involved in the cycle. The target miRNA-21 then causes corresponding changes in the open-circuit voltage of the self-powered system. Based on this, a sensitive detection method was constructed, within the scope from 0.1 fM to 0.1 nM with a shallow detection limit of 55.2 aM (S/N = 3). The new approach triumphantly has been used to detect miRNA-21 in serum, which provides a compelling new way for early diagnosis of related cancers.

Prevalence and genome characteristics of canine astrovirus in southwest China.

The aim of this study was to investigate canine astrovirus (CaAstV) infection in southwest China. We collected 107 faecal samples from domestic dogs with obvious diarrhoea. Forty-two diarrhoeic samples (39.3 %) were positive for CaAstV by RT-PCR, and 41/42 samples showed co-infection with canine coronavirus (CCoV), canine parvovirus-2 (CPV-2) and canine distemper virus (CDV). Phylogenetic analysis based on 26 CaAstV partial ORF1a and ORF1b sequences revealed that most CaAstV strains showed unique evolutionary features. Interestingly, putative recombination events were observed among four of the five complete ORF2 sequences cloned in this study, and three of the five complete ORF2 sequences formed a single unique group, suggesting that these strains could be a novel genotype. We successfully sequenced the complete genome of one CaAstV strain (designated 2017/44/CHN), which was 6628 nt in length. The features of this genome include putative recombination events in the ORF1a, ORF1b and ORF2 genes, while the ORF2 gene had a continuous insertion of 7 aa in region II compared with the other complete ORF2 sequences available in GenBank. Phylogenetic analysis showed that 2017/44/CHN formed a single group based on genome sequences, suggesting that this strain might be a novel genotype. The results of this study revealed that CaAstV circulates widely in diarrhoeic dogs in southwest China and exhibits unique evolutionary events. To the best of our knowledge, this is the first report of recombination events in CaAstV, and it contributes to further understanding of the genetic evolution of CaAstV.

Prevalence and genomic characteristics of canine kobuvirus in southwest China.

To investigate canine kobuvirus (CaKoV) infection in southwest China, 107 fecal samples were collected from dogs with obvious diarrhea in Sichuan and Chongqing regions, China. CaKoV infection was detected in 54 diarrheic samples (50.46%) by RT-PCR targeting a partial fragment (504 bp) of the 3D gene. Comparison of these partial 3D gene sequences from 14 of these CaKoV-positive samples show 95.4%-99.0% nucleotide (nt) identity within this group, and nt identities ranging from 93.1% to 98.2% with previously reported CaKoV 3D gene sequences. Additionally, we amplified five VP1 gene sequences and analyzed the inferred phylogeny. Amino acid (aa) identities of the five VP1 gene sequences were 81.5%-89.4% with those previously reported. Furthermore, one complete CaKoV genome was successfully obtained from a positive sample and designated SMCD-59/CHN/2015. This genome consisted of 8,184 nt, and shared 92.9%-96.6% nt identity (97.6%-98.1% aa identity) with other reported CaKoV genomes. This study provides proof that CaKoV circulates in diarrheic dogs in southwest China, and that these viruses exhibit unique genetic characteristics.

EXPRESS: Enhanced intentional inhibition with increased subliminal action preparation.

Intentional inhibition, the ability to voluntarily inhibit or suspend an action preparation, is closely related to self-control. It is widely believed that subliminal stimuli can also activate action preparation, but whether intentional inhibition is enhanced or disrupted with greater subliminal action preparation remains unclear. In this study, participants voluntarily decided whether or not to perform the action in the scenario with subliminal action preparation, and the strength of the action preparation was manipulated by a precueing procedure. The results, based on behavioral measures and drift-diffusion models, showed that intentional inhibition enhanced with increasing subliminal action preparation, suggesting that as subliminal action preparation increases, people are more inclined to make inhibitory decisions. This study provides evidence for a framework in which strong subliminal action preparation induces enhanced cognitive monitoring.

Traditional Chinese Patent Medicine in the Treatment of Alzheimer's Disease: A Systematic Review and Network Meta-Analysis.

The objective of this study was to evaluate the efficacy and safety of Chinese patent medicine compared with western medicine in the treatment of Alzheimer's disease using the Network Meta-analysis. This study retrieved relevant studies from 7 databases, and the retrieval time was from the establishment of each database to June 2022. After the screening, data extraction, and quality assessment, 47 studies were finally analyzed, involving 11 Chinese patent medicines. The results demonstrated that Chinese patent medicine intervention was superior to oral western medicine treatment in improving the patient's condition as assessed by the Mini-mental State Examination (MMSE), Activities of Daily Living (ADL), effective rate, and Alzheimer's Disease Assessment Scale-Cognitive section (ADAS-Cog). Particularly, the effect of Chinese patent medicine combined with western medicine intervention was prominent. Meanwhile, Chinese patent medicine intervention in AD did not significantly increase the risk of adverse reactions. The results of the Network Meta-analysis demonstrated that Chinese patent medicine combined with western medicine had statistically significant differences in the MMSE score, ADL score, effective rate, and ADAS-Cog score, compared with both western medicine alone and Chinese patent medicine alone. In terms of adverse reactions, the difference between Chinese patent medicine intervention and simple oral western medicine was statistically significant. The results of further ranking probability analysis demonstrated that Chinese patent medicine combined with western medicine intervention ranked first in terms of MMSE, ADL, effective rate, and ADAS-Cog. Additionally, oral Chinese patent medicine intervention alone ranked first in reducing adverse reactions. In the funnel plots of the MMSE, ADL, and effective rate, most studies were symmetrically distributed on both sides of the midline, where small sample effects and publication bias might exist to some extent. However, this conclusion still needs to be combined with clinical syndrome differentiation and treatment, and more large-sample, multi-center, high-quality studies are needed for further verification.

Construction and immunogenicity of a trypsin-independent porcine epidemic diarrhea virus variant.

Porcine epidemic diarrhea virus (PEDV) is a re-emerging enteropathogenic coronavirus that causes high mortality in neonatal piglets. The addition of trypsin plays a crucial role in the propagation of PEDV, but also increases the complexity of vaccine production and increases its cost. Previous studies have suggested that the S2' site and Y976/977 of the PEDV spike (S) protein might be the determinants of PEDV trypsin independence. In this study, to achieve a recombinant trypsin-independent PEDV strain, we used trypsin-dependent genotype 2 (G2) PEDV variant AJ1102 to generate three recombinant PEDVs with mutations in S (S2' site R894G and/or Y976H). The three recombinant PEDVs were still trypsin dependent, suggesting that the S2' site R894 and Y976 of AJ1102 S are not key sites for PEDV trypsin dependence. Therefore, we used AJ1102 and the classical trypsin-independent genotype 1 (G1) PEDV strain JS2008 to generate a recombinant PEDV carrying a chimeric S protein, and successfully obtained trypsin-independent PEDV strain rAJ1102-S2'JS2008, in which the S2 (amino acids 894-1386) domain was replaced with the corresponding JS2008 sequence. Importantly, immunization with rAJ1102-S2'JS2008 induced neutralizing antibodies against both AJ1102 and JS2008. Collectively, these results suggest that rAJ1102-S2'JS2008 is a novel vaccine candidate with significant advantages, including no trypsin requirement for viral propagation to high titers and the potential provision of protection for pigs against G1 and G2 PEDV infections.

The Characterization and Pathogenicity of a Recombinant Porcine Epidemic Diarrhea Virus Variant ECQ1.

Porcine epidemic diarrhea virus (PEDV), a re-emerging enteropathogenic coronavirus, has become the predominant causative agent of lethal diarrhea in piglets, resulting in huge economic losses in many countries. Furthermore, the rapid variability of this virus has increased the emergence of novel variants with different pathogenicities. In this study, 633 fecal samples collected from diarrheic piglets in China during 2017-2019 were analyzed, and 50.08% (317/633) of these samples were PEDV-positive. The full-length spike (S) genes of 36 samples were sequenced, and a genetic evolution analysis was performed. The results showed that thirty S genes belonged to the GII-a genotype and six S genes belonged to the GII-b genotype. From the PEDV-positive samples, one strain, designated ECQ1, was successfully isolated, and its full-length genome sequence was determined. Interestingly, ECQ1 is a recombinant PEDV between the GII-a (major parent) and GII-b (minor parent) strains, with recombination occurring in the S2 domain of the S gene. The pathogenicity of ECQ1 was assessed in 5-day-old piglets and compared with that of the strain EHuB2, a representative of GII-a PEDV. Although both PEDV strains induced similar fecal viral shedding in the infected piglets, ECQ1 exhibited lower pathogenicity than did EHuB2, as evidenced by reduced mortality and less severe pathological changes in the intestines. These data suggest that PEDV strain ECQ1 is a potential live virus vaccine candidate against porcine epidemic diarrhea.

Capacitor-parallel-amplified decoupled photoelectrochemical/electrochromic dual-mode bioassay for sensitive detection of microRNA with high reliability.

To achieve sensitive detection of low-content microRNA, photoelectrochemical/electrochromic dual-mode sensor with intrinsically low background signal has been developed, but the two detection modules are usually designed with a series-connected structure, which may cause signal interference and thus affect the detection reliability. To solve the above problems, a decoupled dual-mode bioassay for sensitive miRNA-21 detection with high reliability is constructed in this work, by selecting two capacitors to realize parallel amplification for the two detection modules, supplemented with a 3D DNA nanoring photoelectrode signal amplification strategy. The complete decoupling of the two detection modes, photoelectrochemical and electrochromic, as well as the use of digital multimeter, improves the reliability and accuracy of the sensor, and also frees it from dependence on electrochemical workstation, making detection more intuitive and faster. With simple structure, low cost, good reproducibility, high sensitivity, and easy operation, the capacitor-parallel-amplified decoupled photoelectrochemical/electrochromic dual-mode bioassay has broad application prospect in on-site point-of-care detection of diseases and low-cost clinical diagnosis. The design idea of decoupled dual-mode detector can also be extended to the construction of other dual-mode methods.

Cyclobutane-Containing Meroditerpenoids, (+)-Isoscopariusins B and C: Structure Elucidation and Biomimetic Synthesis.

(+)-Isoscopariusins B (1) and C (2), two meroditerpenoids containing a 6/6/4 tricyclic carbon skeleton and seven continuous stereocenters, were identified from Isodon scoparius. The structures were determined by nuclear magnetic resonance analysis and concise biomimetic syntheses from readily available alkene 5 in seven and six steps, respectively. An intermolecular [2+2] photocycloaddition with cooperative catalysis of a Lewis acid and an Ir photocatalyst was used to construct a cyclobutane core with four stereogenic centers.

Enhancing biosensing with fourfold amplification and self-powering capabilities: MoS2@C hollow nanorods-mediated DNA hexahedral framework architecture for amol-level liver cancer tumor marker detection.

Two-dimensional carbon-coated molybdenum disulfide (MoS2@C) hollow nanorods are combined with nucleic acid signal amplification strategies and DNA hexahedral nanoframework to construct a novel self-powered biosensing platform for ultra-sensitive dual-mode detection of tumor suppressor microRNA-199a. The nanomaterial is applied on carbon cloth and then modified with glucose oxidase or using as bioanode. A large number of double helix DNA chains are produced on bicathode by nucleic acid technologies including 3D DNA walker, hybrid chain reaction and DNA hexahedral nanoframework to adsorb methylene blue, producing high EOCV signal. Methylene blue also is reduced and an increased RGB Blue value is observed. For microRNA-199a detection, the assay shows a extensive linear range of 0.0001-100 pM with a low detection limit of 4.94 amol/L (S/N = 3). The method has been applied to the detection of actual serum samples, providing a novel method for the accurate and sensitive detection of tumor markers.

WC-High Entropy Alloy Reinforced Long Life Self-Grinding Silage Knife Prepared by Laser Cladding.

The working environment of agricultural knives is bad, which makes the knives wear out easily. A wear resistant layer of AlCoCrFeNi high entropy alloy (HEA) reinforced by tungsten carbide (WC) was prepared by laser cladding on one side of the cutting edge of a 65 Mn silage knife. Both the effects of WC addition on the microstructure and mechanical properties of AlCoCrFeNi (WC)x (x = 0, 0.1, 0.2 and 0.3 in mass percentage) alloys were investigated. All experimental alloys displayed a crystalline structure of simple body centered cubic (BCC). The hardness of the cladding layer increases with the increase of WC content, and the hardness value enhances from 740 HV0.2 to 1060 HV0.2. A self-grinding edge was formed during working for the cladded knives. The cutting quality can be improved and the service life of agricultural knives can be increased meanwhile. The weight loss rate of untreated knives was about 2.64 times that of the cladded knives after a 76 h field experiment.

Establishment of a duplex TaqMan RT-PCR for the differential detection of RHDV GI.1 and GI.2.

BACKGROUND: Rabbit haemorrhagic disease (RHD) is a highly contagious and acute fatal hepatitis of the European rabbit (Oryctolagus cuniculus), caused by a calicivirus (genus Lagovirus). Up to 2010, all RHD viruses (RHDV) isolated belonged to one genotype. In 2010, a new genotype of RHDV (RHDV2/b, currently designated GI.2 based on phylogenetic analysis) emerged in France. The aim of this study was to develop a rapid, simple, specific and sensitive TaqMan real-time PCR assay for the classic strain of RHDV and RHDV2 detection. Specific primers and probes were designed for the VP60 gene of RHDV and RHDV2 within the conserved region of viral genome. RESULTS: This study was demonstrated to be highly specific for RHDV and RHDV2, without cross-reactions with other non-targeted viruses. The detection limit of this work was 102 copies of RHDV and RHDV2, respectively. The coefficient of variation of the assay was less than 5% for both intra-assay and inter-assay. The reproducibility of method was assessed using plasmids and the coefficient of variation obtained was 0.2-3.70. Of 79 clinical samples, 68 were positive samples (86.08%), of which 60 were classic RHDV variants (75.9%), 4 were co-infected (5.06%) and 8 were RHDV2 (10.12%), those results are more sensitivity compare with conventional RT-PCR RT-PCR. CONCLUSIONS: In conclusion, this duplex TaqMan RT-qPCR based on VP60 gene of RHDV and RHDV2 could be a valuable tool in diagnose and molecular epidemiological study of the RHDV and RHDV2.

Gunao-Yizhi decoction combined with donepezil for vascular dementia: A systematic review and meta-analysis.

BACKGROUND: Gunao-Yizhi decoction has the effects of supplementing intelligence, strengthening marrow, resolving phlegm, and reducing turbidity. It is clinically used for the treatment of vascular dementia (VaD). However, there is still a lack of systematic evaluation of its efficacy and safety. This review conducted a systematic review of the current evidence on the efficacy and safety of Gunao-Yizhi decoction combined with donepezil for VaD. METHODS: China National Knowledge Infrastructure (CNKI), Wanfang database (Wanfang), Chinese Science and Technology Periodical Database (VIP), China Biology Medicine disc (CBM), MEDLINE, EMBASE, and Cochrane Library were searched for randomized controlled trials on Gunao-Yizhi decoction combined with donepezil for VaD. RevMan 5.3 software was used for data analysis. RESULTS: Twelve studies were obtained, including 1036 patients. Compared with donepezil alone, meta-analysis showed that Gunao-Yizhi decoction combined with donepezil could improve clinical efficacy, mini-mental state examination (MMSE) score, Hasegawa dementia scale (HDS), increase the level of superoxide dismutase (SOD) in serum, and reduce the level of malonaldehyde dismutas (MDA) in serum. The GRADE system was adopted to evaluate the outcome index. Clinical efficiency and the MMSE score were evaluated as very-low-quality evidence. HDS score, serum SOD level, and serum MDA level were evaluated as low-quality evidence. CONCLUSION: Gunao-Yizhi decoction combined with donepezil has a significant prevalence in the treatment of vascular dementia, with no increase in adverse events. Gunao-Yizhi decoction can be recommended for routine use in the treatment of VaD.

The Impact of Supervisor-Subordinate Incongruence in Power Distance Orientation on Subordinate Job Strain and Subsequent Job Performance.

Employee strain is estimated to cost American companies as much as $500 billion in lost productivity annually, and a leading cause of workforce stress is disagreements with other people (Cook, 2017; Mental Health America, 2017). In this study, we investigate supervisor-subordinate value incongruence as a cause of employee strain. Specifically, this study examines the effect of supervisor-subordinate power distance orientation incongruence on the subordinate's job strain which, in turn, influences the subordinate's job performance. Using a sample of 172 supervisor-subordinate dyads, we find that incongruence on power distance orientation increases subordinate job strain. Supervisor-subordinate incongruence resulted in more job strain which, in turn, resulted in lower job performance. Results reveal that the alignment of subordinates' cultural values with those of their supervisors may mitigate negative experiences and facilitate more positive work outcomes.

Reusing wasteroot of Rubia wallichiana dyeing from Monpa of Tibet in China.

Humans have dyed textiles and leather, colored food, and paint body parts using natural dyes throughout history. Natural dyes have suffered drastically due to recent socioeconomic changes and replacement with synthetic dye in the textile industry. Hence, it is urgent to study indigenous dye plants and dyeing craft in local communities to protect these resources' potential ecological, economic, and cultural values. In 11 Monpa villages of Mêdog County, South-east Tibet, China, we conducted field research to record the indigenous method of cloth dyeing using madder dye. An aqueous extract of the root of Rubia wallichiana is a traditional madder dye. In this study, we used traditional dye and ethyl alcohol extract of the residue of aqueous extract. Two fabrics were dyed with the extractions in the presence of one of the metallic mordants or biomordants. Pigment compounds from aqueous extraction of madder and ethyl alcohol extraction of recycled madder were evaluated using Phytochemical, UV-visible spectroscopy, and FTIR test. We carried out One-way ANOVA and Duncan's new multiple range method to analyze different dying approaches and conditions. The dyed fabrics were evaluated by indicators of color strength and fastness, including washing, rubbing, and perspiration. The findings revealed the potentiality of biomordants to improve the dyeing properties of madder. The dyeing properties of recycled madder were marginally better than traditional madder. The results revealed the feasibility of enhancing the dyeing property and reuse of the residue from madder dyeing. The improved dyeing and reuse of residue can improve local ecological, economic benefits, and cultural heritage while applying research findings for the subsequent commercialization of plant dyes.

Repellent, larvicidal and adulticidal activities of essential oil from Dai medicinal plant Zingiber cassumunar against Aedes albopictus.

Zingiber cassumunar is an important plant used in traditional medicine and as a natural mosquito repellent. However, the compounds responsible for the repellent activity of the plant are still unknown. The aim of the study is to identify the components of Z. cassumunar essential oil that show repellent activity against Aedes albopictus. We also evaluated the larvicidal and adulticidal activities of Z. cassumunar essential oil against Ae. albopictus. In-cage mosquito repellent experiments showed that Z. cassumunar essential oil possessed moderate repellent activity with a minimum effective dose (MED) of 0.16 ± 0.01 mg/cm2, compared to reference standard N,N-diethyl-3-methylbenzamide (DEET, 0.03 ± 0.01 mg/cm2). Bioassay-guided fractionation identified the major active compound of Z. cassumunar essential oil as (-)-terpinen-4-ol (1) (MED: 0.19 ± 0 mg/cm2). We also found that Z. cassumunar essential oil showed moderate larvicidal activity against first instar larvae of Ae. albopictus with a LC50 (50% lethal concentration) of 44.9 µg/L after 24 h. Fumigation bioassays showed that Z. cassumunar essential oil exhibits moderate adulticidal activity against Ae. albopictus with a LC50 of 5.44%, while (-)-terpinen-4-ol showed significant adulticidal activity with a LC50 of 2.10% after 24 h. This study verifies that the Z. cassumunar essential oil has mosquito repellent activity, and that (-)-terpinen-4-ol is mainly responsible for this activity. Furthermore, this study provides scientific support for the folk usage of Z. cassumunar essential oil as mosquito repellent and indicates that Z. cassumunar essential oil and (-)-terpinen-4-ol can be used as plant-derived repellents and insecticides for mosquito control.

[Arrhythmia after a positive head-up tilt table test].

OBJECTIVE: to study the characteristics of arrhythmia after a positive head-up tilt table test (HUTT). METHODS: head-up tilt table test (BHUT) or sublingual nitroglycerin-provocation head-up tilt table test (SNHUT) were performed in 1374 patients at the Second Xiangya Hospital of Central South University from March of 2001 to August of 2009. Arrhythmias were recorded in 169 patients after a positive HUTT [57 male, age 6 - 65 years, 86 children < 18 years, mean age (23.1 ± 14.8) years]. RESULTS: arrhythmias developed in 75 patients (44.38%) post a positive BHUT and in 94 patients (55.62%) post a positive SNHUT. Major types of arrhythmias were sinus bradycardia (143/169, 84.62%), junctional escape rhythm (55/169, 32.54%) and sinus arrest (26/169, 15.38%). Sinus bradycardia was more common in adult (P < 0.01). Occurrence of junctional escape rhythm and sinus arrest was not affected by age, gender and test mode. Arrhythmia and the manifestation of syncope or pre-syncope occurred simultaneously in 77 (45.56%) patients and mainly in BHUT, while arrhythmia appeared later than the syncope manifestation in 92 (54.44%) patients and mainly in SNHUT (P < 0.05). Arrhythmia and blood pressure reduction occurred simultaneously in 84 (53.50%) cases and mainly in BHUT, while arrhythmia appeared later than reduction of blood pressure in 73 (46.50%) cases and mainly in SNHUT (P < 0.01). CONCLUSIONS: (1) the common types of arrhythmia were sinus bradycardia, junctional escape rhythm and sinus arrest after a positive HUTT. Occurrence of sinus arrest was not affected by age, gender and test mode. (2) In BHUT, arrhythmia occurred mostly simultaneously with the manifestation of syncope or pre-syncope and blood pressure reduction, while arrhythmia appeared later in SNHUT.

[Clinical analysis of vasovagal syncope in children].

OBJECTIVE: To study the changes in clinical features of vasovagal syncope (VVS) in children. METHODS: From January 2000 to September 2009, 841 children with unexplained syncope or prodromata were enrolled. They were assigned to two groups according to the period of visiting hospital: group A (from January 2000 to December 2004, n=129) and group B (from January 2005 to September 2009, n=712). They were assigned to three age groups: 4-6 years old, 7-10 years old and 11-18 years old. A head-up tilt table test (HUTT) was performed on all the subjects. RESULTS: The total positive rate of HUTT was 45.3% (381/841). Compared with that in group A, the positive rate of HUTT in group B increased significantly (47.5% vs 33.3%; P<0.05). The positive rate of HUTT in female children was significantly higher than that in male children (49.3% vs 37.9%; P<0.05). The positive rate of HUTT increased with age and it was the highest in children at age of 11-18 years (49.2%), followed by in children at age of 7-10 years (44.1%) and 4-6 years (37.1%) (P<0.05). The children at age of 7-10 years and 11-18 years from group B showed significantly higher positive rate of HUTT than those from group A (46.2% vs 27.8%; 54.0% vs 32.6%, P<0.05). Vasodepressor type was the most common response type (70.9%) shown by HUTT compared with mixed type (25.5%) and cardioinhibitory type (3.6%) (P<0.05). The proportion of children with vasodepressor response type in group B was significantly higher than that in group A (72.5% vs 58.1%; P<0.05). CONCLUSIONS: There were obvious changes in the prevalence of VVS and response types before and after five years, suggesting that the development of VVS may be attributed to many factors, such as social factors, mental factor and life style.