Enhanced polarization switching characteristics of HfO2 ultrathin films via acceptor-donor co-doping.

In the realm of ferroelectric memories, HfO2-based ferroelectrics stand out because of their exceptional CMOS compatibility and scalability. Nevertheless, their switchable polarization and switching speed are not on par with those of perovskite ferroelectrics. It is widely acknowledged that defects play a crucial role in stabilizing the metastable polar phase of HfO2. Simultaneously, defects also pin the domain walls and impede the switching process, ultimately rendering the sluggish switching of HfO2. Herein, we present an effective strategy involving acceptor-donor co-doping to effectively tackle this dilemma. Remarkably enhanced ferroelectricity and the fastest switching process ever reported among HfO2 polar devices are observed in La3+-Ta5+ co-doped HfO2 ultrathin films. Moreover, robust macro-electrical characteristics of co-doped films persist even at a thickness as low as 3 nm, expanding potential applications of HfO2 in ultrathin devices. Our systematic investigations further demonstrate that synergistic effects of uniform microstructure and smaller switching barrier introduced by co-doping ensure the enhanced ferroelectricity and shortened switching time. The co-doping strategy offers an effective avenue to control the defect state and improve the ferroelectric properties of HfO2 films.

Seeded growth of single-crystal black phosphorus nanoribbons.

Two-dimensional materials have emerged as an important research frontier for overcoming the challenges in nanoelectronics and for exploring new physics. Among them, black phosphorus, with a combination of a tunable bandgap and high mobility, is one of the most promising systems. In particular, black phosphorus nanoribbons show excellent electrostatic gate control, which can mitigate short-channel effects in nanoscale transistors. Controlled synthesis of black phosphorus nanoribbons, however, has remained an outstanding problem. Here we report large-area growth of black phosphorus nanoribbons directly on insulating substrates. We seed the chemical vapour transport growth with black phosphorus nanoparticles and obtain uniform, single-crystal nanoribbons oriented exclusively along the [100] crystal direction. With comprehensive structural calculations, we discover that self-passivation at the zigzag edges holds the key to the preferential one-dimensional growth. Field-effect transistors based on individual nanoribbons exhibit on/off ratios up to ~104, confirming the good semiconducting behaviour of the nanoribbons. These results demonstrate the potential of black phosphorus nanoribbons for nanoelectronic devices and also provide a platform for investigating the exotic physics in black phosphorus.

Colossal Ionic Conductivity in Interphase Strain-Engineered Nanocomposite Films.

Owing to their wide application in oxide-based electrochemical and energy devices, ion conductors have attracted considerable attention. However, the ionic conductivity of the developed systems is still too low to satisfy the low-temperature application. In this study, by developing the emergent interphase strain engineering method, we achieve a colossal ionic conductivity in SrZrO3-xMgO nanocomposite films, which is over one order of magnitude higher than that of the currently widely used yttria-stabilized zirconia below 673 K. Atomic-scale electron microscopy studies ascribe this superior ionic conductivity to the periodically well-aligned SrZrO3 and MgO nanopillars that feature coherent interfaces. Wherein, a tensile strain as large as +1.7% is introduced into SrZrO3, expanding the c-lattice and distorting the oxygen octahedra to decrease the oxygen migration energy. Combining with theoretical assessments, we clarify the strain-dependent oxygen migration path and energy and unravel the mechanisms for strain-tuned ionic conductivity. This study provides a new scope for the property improvement of wide-range ion conductors by strain engineering.

Structural Polymorphism Kinetics Promoted by Charged Oxygen Vacancies in HfO_{2}.

Defects such as oxygen vacancy are widely considered to be critical for the performance of ferroelectric HfO_{2}-based devices, and yet atomistic mechanisms underlying various exotic effects such as wake-up and fluid imprint remain elusive. Here, guided by a lattice-mode-matching criterion, we systematically study the phase transitions between different polymorphs of hafnia under the influences of neutral and positively charged oxygen vacancies using a first-principles-based variable-cell nudged elastic band technique. We find that the positively charged oxygen vacancy can promote the transition of various nonpolar phases to the polar phase kinetically, enabled by a transient high-energy tetragonal phase and extreme charge-carrier-inert ferroelectricity of the polar Pca2_{1} phase. The intricate coupling between structural polymorphism kinetics and the charge state of the oxygen vacancy has important implications for the origin of ferroelectricity in HfO_{2}-based thin films as well as wake-up, fluid imprint, and inertial switching.

Exploring cost-effective measure portfolios for ecosystem services optimization under large-scale vegetation restoration.

Ecosystem services-based land management incorporates environmental features and social needs, providing an important opportunity to realize global sustainability goals. Recent decades, the interaction among water-related ecosystem services (ESs) is getting ambiguous during regional vegetation restoration, which entails challenges for coordinating restoration actions, economic resources, and water-soil resources' availability. In this study, we first explored mechanism of trade-offs among five water-related ESs in the Chinese Loess Plateau under vegetation restoration. Given the decreased baseflow and its widespread trade-offs with water quality, we then developed four scenarios aiming at enhancing the baseflow and nutrient retention in a cost-effective way, by engaging a spatially explicit biophysical software tool-the RIOS model. Moreover, we selected four typical watersheds in the Loess Plateau as cases to demonstrate the differentiated information on the budget levels and the activity sites. The results indicated that, a deep mechanism of scale effects of trade-off among ESs was largely related to spatial heterogeneity rather than spatial resolution, which also affected activity portfolios under different ES scenarios. For the entire Loess Plateau, activity of forest maintenance should be concentrated on the cost-effective locations of investment for the enhancement of baseflow and nutrient retention. Under the regular budget scenarios, trade-offs only could be locally alleviated in reality, while dropping the high-cost ES objectives is an advisable strategy for minimizing investment risk. Taking conservation agricultural practices in the plain river basins should be regarded as a priority when budget can be increased. In contrast, an approach of 'governing by non-interference' for typical watersheds of re-vegetation was sensible strategy for avoiding trade-offs aggravation. These findings emphasized interrelation between the mechanism of ESs trade-offs and activity portfolios, which is an important basis for the implementation of conservation activities in real world context, and a rational reference for the simulation of desired ES goals in future studies.

Ultrahigh Oxygen Ion Mobility in Ferroelectric Hafnia.

Ferroelectrics and ionic conductors are important functional materials, each supporting a plethora of applications in information and energy technology. The underlying physics governing their functional properties is ionic motion, and yet studies of ferroelectrics and ionic conductors are often considered separate fields. Based on first-principles calculations and deep-learning-assisted large-scale molecular dynamics simulations, we report ferroelectric-switching-promoted oxygen ion transport in HfO_{2}, a wide-band-gap insulator with both ferroelectricity and ionic conductivity. Applying a unidirectional bias can activate multiple switching pathways in ferroelectric HfO_{2}, leading to polar-antipolar phase cycling that appears to contradict classical electrodynamics. This apparent conflict is resolved by the geometric-quantum-phase nature of electric polarization that carries no definite direction. Our molecular dynamics simulations demonstrate bias-driven successive ferroelectric transitions facilitate ultrahigh oxygen ion mobility at moderate temperatures, highlighting the potential of combining ferroelectricity and ionic conductivity for the development of advanced materials and technologies.

Tet-mediated DNA demethylation regulates specification of hematopoietic stem and progenitor cells during mammalian embryogenesis.

Ten-eleven translocation (Tet) enzymes promote DNA demethylation by oxidizing 5-methylcytosine. They are expressed during development and are essential for mouse gastrulation. However, their postgastrulation functions are not well established. We find that global or endothelial-specific loss of all three Tet enzymes immediately after gastrulation leads to reduced number of hematopoietic stem and progenitor cells (HSPCs) and lethality in mid-gestation mouse embryos. This is due to defects in specification of HSPCs from endothelial cells (ECs) that compromise primitive and definitive hematopoiesis. Mechanistically, loss of Tet enzymes in ECs led to hypermethylation and down-regulation of NFκB1 and master hematopoietic transcription factors (Gata1/2, Runx1, and Gfi1b). Restoring Tet catalytic activity or overexpression of these factors in Tet-deficient ECs rescued hematopoiesis defects. This establishes Tet enzymes as activators of hematopoiesis programs in ECs for specification of HSPCs during embryogenesis, which is distinct from their roles in adult hematopoiesis, with implications in deriving HSPCs from pluripotent cells.

Key residues of the receptor binding motif in the spike protein of SARS-CoV-2 that interact with ACE2 and neutralizing antibodies.

Coronavirus disease 2019 (COVID-19), caused by the novel human coronavirus SARS-CoV-2, is currently a major threat to public health worldwide. The viral spike protein binds the host receptor angiotensin-converting enzyme 2 (ACE2) via the receptor-binding domain (RBD), and thus is believed to be a major target to block viral entry. Both SARS-CoV-2 and SARS-CoV share this mechanism. Here we functionally analyzed the key amino acid residues located within receptor binding motif of RBD that may interact with human ACE2 and available neutralizing antibodies. The in vivo experiments showed that immunization with either the SARS-CoV RBD or SARS-CoV-2 RBD was able to induce strong clade-specific neutralizing antibodies in mice; however, the cross-neutralizing activity was much weaker, indicating that there are distinct antigenic features in the RBDs of the two viruses. This finding was confirmed with the available neutralizing monoclonal antibodies against SARS-CoV or SARS-CoV-2. It is worth noting that a newly developed SARS-CoV-2 human antibody, HA001, was able to neutralize SARS-CoV-2, but failed to recognize SARS-CoV. Moreover, the potential epitope residues of HA001 were identified as A475 and F486 in the SARS-CoV-2 RBD, representing new binding sites for neutralizing antibodies. Overall, our study has revealed the presence of different key epitopes between SARS-CoV and SARS-CoV-2, which indicates the necessity to develop new prophylactic vaccine and antibody drugs for specific control of the COVID-19 pandemic although the available agents obtained from the SARS-CoV study are unneglectable.

Rinf Regulates Pluripotency Network Genes and Tet Enzymes in Embryonic Stem Cells.

The Retinoid inducible nuclear factor (Rinf), also known as CXXC5, is a nuclear protein, but its functions in the context of the chromatin are poorly defined. We find that in mouse embryonic stem cells (mESCs), Rinf binds to the chromatin and is enriched at promoters and enhancers of Tet1, Tet2, and pluripotency genes. The Rinf-bound regions show significant overlapping occupancy of pluripotency factors Nanog, Oct4, and Sox2, as well as Tet1 and Tet2. We found that Rinf forms a complex with Nanog, Oct4, Tet1, and Tet2 and facilitates their proper recruitment to regulatory regions of pluripotency and Tet genes in ESCs to positively regulate their transcription. Rinf deficiency in ESCs reduces expression of Rinf target genes, including several pluripotency factors and Tet enzymes, and causes aberrant differentiation. Together, our findings establish Rinf as a regulator of the pluripotency network genes and Tet enzymes in ESCs.

Transactivation of Met signalling by semaphorin4D in human placenta: implications for the pathogenesis of preeclampsia.

OBJECTIVE: The signalling of the receptor tyrosine kinase Met is critical in promoting trophoblast cell invasion, and the deficiency in HGF/Met signalling is associated with preeclampsia. The semaphorin family member semaphorin4D (sema4D) and its receptor Plexin-B1 have been reported to control tumour cell invasion by coupling with Met. We hypothesized that sema4D/Plexin-B1 may promote trophoblast invasion by activating Met, and downregulation of sema4D/Plexin-B1 may account for the deficiency in Met signalling in preeclamptic placenta. METHODS: In this study, Met and Erk activation and the expression of sema4D/Plexin-B1 in normal and preeclamptic placentas were comparably measured. The role of sema4D in trophoblast cell invasion and tubulogenesis was examined in vitro using the Transwell invasion assay and tube formation assay in trophoblast-endothelial cell co-culture model. RESULTS: Met, sema4D and Plexin-B1 co-localized in various subtypes of human trophoblast cells, including villous trophoblasts and extravillous trophoblasts (EVTs). In early-onset preeclampsia (E-PE) placentas, the phosphorylated Met and Erk as well as sema4D and Plexin-B1 were much lower than those in gestational week-matched preterm-labour (PTL) placentas. In human trophoblast HTR8/SVneo cell line, sema4D could promote Met and Erk phosphorylation as well as enhance trophoblast cell invasion and tubulogenesis with endothelial cells. Moreover, the effect of sema4D on HTR8/SVneo could be blocked by knocking down Met with specific siRNA. CONCLUSION: The crosstalk between sema4D and Met could transactivate Met to promote trophoblast cell invasion and differentiation, and decreased expression of sema4D and Plexin-B1 may be responsible for the deficiency in Met signalling and the development of preeclampsia.

The intervention effect of aspirin on a lipopolysaccharide-induced preeclampsia-like mouse model by inhibiting the nuclear factor-κB pathway.

Preeclampsia is a severe pregnancy-related disorder, and patients usually present with high circulating inflammatory factor levels and excessive activation of the nuclear factor-κB (NF-κB) pathway. Administration of aspirin (ASP) is effective for preventing preeclampsia, and thus, we propose that ASP might affect placental function by regulating the NF-κB pathway. Systemic lipopolysaccharide (LPS) (20 µg/kg) was used to induce preeclampsia-like pregnant mouse model, and low-dose ASP (15.2 mg/kg) was administrated. Here, we report significantly increased circulatory expression levels of the proinflammatory cytokines tumor necrosis factor-alpha, interleukin-6, and soluble Fms-related tyrosine kinase-1 in LPS-treated pregnant mice, accompanied by kidney and placental dysfunction. Low-dose ASP treatment significantly reversed the preeclampsia-like phenotype, lowering hypertension, decreasing proteinuria, and ameliorating fetal growth retardation. Moreover, the excessive activation of NF-κB signaling in mice placentae induced by LPS was significantly reduced by ASP. In JEG-3 cells, LPS activated the NF-κB signaling pathway by upregulating the expression of cyclooxygenase-2 (COX-2) and related inflammatory factors, whereas the invasion ability of JEG-3 cells was weakened. However, ASP administration impeded NF-κB signaling activation, downregulated COX-2 and inflammatory factor expression, and rescued trophoblast invasion. This study provides new evidence that low-dose ASP is beneficial for preeclampsia prevention by inhibiting NF-κB and its downstream signaling pathways in trophoblast cells.

dNK cells facilitate the interaction between trophoblastic and endothelial cells via VEGF-C and HGF.

Decidual NK (dNK) cells, identified as CD56brightCD16-CD3-, account for ~70% of lymphocytes within the uterine wall during early pregnancy. Accumulating evidence suggests that tight interactions between placental trophoblasts and dNK cells are critical for trophoblast cell differentiation. However, the underlying mechanism remains to be explored in detail. In the present study, conditioned medium (CM) was collected from cultured primary human dNK cells. Primary cytotrophoblasts (CTBs) or the human trophoblast cell line HTR8/SVneo was treated with dNK-CM and co-cultured with human umbilical vein endothelial cells (HUVECs) in a three-dimensional Matrigel scaffold, and the formation of tube structures was dynamically monitored with live cell imaging. Trophoblast invasion was analyzed with a transwell invasion assay. The data demonstrated that the treatment of HTR8/SVneo cells or CTBs with dNK-CM remarkably promoted trophoblast invasion and tube formation in the presence of HUVECs. The epithelial marker E-cadherin was reduced, while the expression of endothelial markers NCAM, VE-cadherin and integrin ß1 was significantly promoted in the HTR8/SVneo cells upon treatment with dNK-CM. Antibody blocking experiments revealed that the dNK cells promoted trophoblast invasion through the production of IL-8 and HGF, and they induced trophoblast differentiation toward endothelial phenotype by producing VEGF-C and HGF. These results provide new evidence to clarify the finely tuned interactions between trophoblasts and dNK cells at the maternal-fetal interface.

Testosterone Represses Estrogen Signaling by Upregulating miR-22: A Mechanism for Imbalanced Steroid Hormone Production in Preeclampsia.

Preeclampsia, a multisystem syndrome occurring during mid- to late gestation in humans, is a leading cause of maternal and perinatal morbidity and mortality. Patients usually present with high circulating testosterone and reduced estradiol production, but the mechanisms remain unclear. Revealing the mechanism that modulating the imbalance of testosterone and estradiol in preeclampsia is of great value in understanding the cause of the disease. The placenta is the predominant source of steroid hormone production during gestation, and we observed markedly increased 17ß-HSD3 (17ß-hydroxysteroid dehydrogenase 3) levels and downregulated aromatase expression, the key enzymes responsible for synthesis of testosterone and estradiol, respectively, in preeclamptic placentas compared with controls. Furthermore, we found a significant upregulation of microRNA (miR)-22 in preeclamptic placentas. In a trophoblast cell line, JEG-3 cells, testosterone repressed the expression of aromatase and estrogen receptor α and the production of estradiol while promoting miR-22 expression. miR-22 directly targeted and inhibited estrogen receptor α expression while indirectly decreasing aromatase expression and estradiol production by interfering with estrogen receptor α signaling. Furthermore, inhibition of miR-22 expression significantly reversed the inhibitory effect of testosterone on de novo estradiol synthesis in human trophoblastic cells. The findings reveal a mechanism underlying the balanced production of androgen and estrogen modulated by miR-22 in the human placenta and provide new insights into the pathogenesis of preeclampsia from the aspect of endocrine regulation.

GnRH regulates trophoblast invasion via RUNX2-mediated MMP2/9 expression.

STUDY HYPOTHESIS: We hypothesized that Runt-related transcription factor 2 (RUNX2), matrix metalloproteinase (MMP)2 and MMP9 are involved in basal and gonadotrophin-releasing hormone (GnRH)-induced human extravillous trophoblast (EVT) cell invasion. STUDY FINDING: Our finding indicates that GnRH-induced RUNX2 expression enhances the invasive capacity of EVT cells by modulating the expression of MMP2 and MMP9. WHAT IS KNOWN ALREADY: GnRH is expressed in first-trimester placenta and exerts pro-invasive effects on EVT cells in vitro. RUNX2 regulates MMP2 and MMP9 expression and is often associated with invasive phenotypes. STUDY DESIGN, SAMPLES/MATERIALS, METHODS: First-trimester human placenta (n = 9) was obtained from women undergoing elective termination of pregnancy. The localization of RUNX2, MMP2 and MMP9 in first-trimester human placenta was examined by immunohistochemistry. Primary or immortalized (HTR-8/SVneo) EVT cells were treated alone or in combination with GnRH, GnRH antagonist Antide, MAPK kinase inhibitor PD98095, phosphatidylinositol 3-kinase inhibitor LY294002, MMP2/9 inhibitor or small interfering RNAs (siRNAs) targeting RUNX2, MMP2 and/or MMP9. Protein and mRNA levels were measured by western blot and RT-PCR, respectively. Cell invasiveness was evaluated by transwell Matrigel or collagen I invasion assays. MAIN RESULTS AND THE ROLE OF CHANCE: RUNX2, MMP2 and MMP9 were detected in the cell column regions of human first-trimester placental villi. GnRH treatment increased RUNX2 mRNA and protein levels in HTR-8/SVneo cells and primary EVTs, and these effects were attenuated by co-treatment with Antide, PD98095 or LY294002. Down-regulation of RUNX2 by siRNA reduced basal and GnRH-induced MMP2/9 expression and cell invasion. Moreover, pharmacological inhibition or siRNA-mediated knockdown of MMP2/9 reduced basal and GnRH-induced cell invasion. LIMITATIONS, REASONS FOR CAUTION: The lack of an in vivo model is the major limitation of our in vitro study. WIDER IMPLICATIONS OF THE FINDINGS: Our findings provide important insight into the functions of the GnRH - GnRH receptor system in early implantation and placentation. LARGE SCALE DATA: Not applicable. STUDY FUNDING AND COMPETING INTERESTS: This research was supported by Canadian Institutes of Health Research (Grant #143317) to P.C.K.L. The authors have nothing to disclose.

AP-1 Transcription Factors c-FOS and c-JUN Mediate GnRH-Induced Cadherin-11 Expression and Trophoblast Cell Invasion.

GnRH is expressed in first-trimester human placenta and increases cell invasion in extravillous cytotrophoblasts (EVTs). Invasive phenotypes have been reported to be regulated by transcription factor activator protein 1 (AP-1) and mesenchymal cadherin-11. The aim of our study was to investigate the roles of AP-1 components (c-FOS/c-JUN) and cadherin-11 in GnRH-induced cell invasion in human EVT cells. Phosphorylated c-FOS and phosphorylated c-JUN were detected in the cell column regions of human first-trimester placental villi by immunohistochemistry. GnRH treatment increased c-FOS, c-JUN, and cadherin-11 mRNA and protein levels in immortalized EVT (HTR-8/SVneo) cells. Moreover, GnRH treatment induced c-FOS and c-JUN protein phosphorylation and nuclear accumulation. Pretreatment with antide, a GnRH antagonist, attenuated GnRH-induced cadherin-11 expression. Importantly, basal and GnRH-induced cadherin-11 expression and cell invasion were reduced by small interfering RNA-mediated knockdown of c-FOS, c-JUN, and cadherin-11 in HTR-8/SVneo cells. Our results suggest that GnRH induces the expression and phosphorylation of the AP-1 transcription factors c-FOS and c-JUN in trophoblast cells, which contributes to GnRH-induced elevation of cadherin-11 expression and cell invasion.

[Oral health status and its correlation with oral health knowledge among middle-aged people in Dongxiang, Bonan, and Yugur].

OBJECTIVE: To provide basic data for the prevention of oral diseases in minorities by investigating the oral health status and behavior related to oral health knowledge of individuals aged 35 to 44 years in Dongxiang, Bonan, and Yugur. METHODS: The caries and periodontal health of 445 individuals aged 35 to 44 years were examined according to the method and criterion prescribed by the World Health Organization and the Third National Oral Health Epidemiologic Investigation. A questionnaire survey on related oral health knowledge and behavior was conducted. RESULTS: The crown caries prevalence rate in Dongxiang, Baoan, and Yugur were 48.28%, 79.47%, and 67.11%, respectively; the root caries prevalence rates were 38.62%, 69.54%, and 42.95%, respectively. The rates of gum bleeding in Dongxiang, Bonan, and Yugur were 86.90%, 90.07%, and 65.77%, respectively. The rates of dental calculus in Dongxiang, Bonan, and Yugur were 99.31%, 100.00%, 99.33%, respectively, and the rates of periodontal bags were 68.97%, 67.55%, and 43.62%, respectively. Only 69.84% of the respondents brush their teeth every day; 94.90% of the respondents do not floss. Only 20.19% of the respondents contact a doctor for a toothache, and 42.23% of the respondents have never seen a dentist. CONCLUSION: Caries morbidity is high among the respondents aged 35 to 44 years from Dongxiang, Bonan, and Yugur. The periodontal health status and oral hygiene of the respondents are poor, and behavior related to oral health knowledge is insufficient. Thus, more attention must be provided to the prevention and control of caries and periodontal diseases among middle-aged people in the area.

[A study of association between the interleukin-1 single nucleotide polymorphism and risk of chronic periodontitis among the Hui and Dongxiang minorities in Gansu province].

OBJECTIVE: To examine and analyze the interleukin (IL)-1B gene single nucleotide polymorphism (SNP) at positions +3954, and explore the association between SNP and risk of chronic periodontitis (CP) among the Hui and Dongxiang minorities in Gansu province. METHODS: CP group consisted of 215 patients from Hui and Dongxiang and healthy control group consisted of 219 subjects. Anti-coagulated peripheral blood sample was obtained from each subject and genomic DNA was extracted from each sample. SNP at IL-1B+3954 were analyzed by standard polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. RESULTS: Statistically significant differences were found in genotype and allele frequencies between CP group and healthy control group. The exist of position alleles C increased the incidence of CP. The trend of frequency distribution of gene polymorphism above in Dongxiang was the same as that of Hui. CONCLUSION: The present study reveals that IL-1B+3954C/T genotypes are significantly associated with the risk of CP. These results indicate that genetic polymorphism is significantly associated with the risk of CP among the Hui and Dongxiang minorities in Gansu province.

[Study of dental caries and correlated factors of 12-year-old children in Dongxiang, Baoan and Yugu races].

OBJECTIVE: To investigate the epidemiology of dental caries and its correlated factors of 12-year-old children in Dongxiang, Baoan and Yugu races. METHODS: According to the method of third national oral health epidemiologic investigation, 448 12-year-old children in Dongxiang, Baoan and Yugu races were randomly collected and the epidemiological investigation of dental caries, oral bacteriological detection and oral hygiene behavior were carried out. RESULTS: 1) The caries prevalence rate of Dongxiang, Baoan and Yugu races were 40.52%, 44.29%, 46.45%, respectively. The average caries of Dongxiang, Baoan and Yugu races were 0.92, 0.90, 1.13, respectively. 2) The main ranks of Streptococcus mutans in saliva were class 2 and class 3 in Dongxiang and Baoan races. However, it was class 0 or class 1 in Yugu race. The level of Streptococcus mutans in dental plaque was higher in Dongxiang and Baoan races than in Yugu race. 3) The children's everyday brushing rate was higher in Yugu race than in Dongxiang and Baoan races (P<0.01). But there were no difference between Dongxiang and Baoan races. CONCLUSION: The caries prevalence rates of 12-year-old children in Dongxiang, Baoan and Yugu races are high. The main factors of high caries prevalence rate were low brushing rate and dental plaque couldn't be removed effectively. Oral health education should be strengthened in the three race areas.

[Effects of patient-controlled analgesia with small dose ketamine combined with morphine and the influence thereof on plasma beta-endorphin level in patients after radical operation for esophageal carcinoma].

OBJECTIVE: To evaluate the effects of patient-controlled analgesia (PCA) with small dose ketamine combined with morphine on analgesia and influence thereof on the plasma beta-endorphin (EP) level in the patients after radical operation for esophageal carcinoma. METHODS: Thirty ASAI-II patients, aged 35-65, weighing 42-75 kg, with visual analogue score>or=3, undergoing elective radical operation for esophageal carcinoma under general anesthesia received intravenous morphine 2 - 3 mg were randomly divided into 2 equal groups: group m receiving morphine 0.02 mg.kg(-1).h(-1), and with group mk receiving morphine 0.02 mg.kg(-1).h(-1) combined with ketamine 0.08 mg.kg(-1).h(-1) for 50 h. In the course of treatment the patients received intravenous injection of morphine 2-3 mg when the VAS was >or=3. VAS was recorded 4, 8, 20, 24, and 48 h after operation. The amount of morphine used after operation, PCA button pressing times (effective/active), side effects, and vital signs including pulse, saturation of blood oxygen, respiratory rate, heart rate, and average arterial pressure were recorded. Central venous blood samples were collected when entering the operation room (T0), by the end of operation (T1), and 6 h (T2), 24 h (T3), and 48 h (T4) after operation respectively to examine the beta-endorphin level. RESULTS: During the period 4-48 h after operation the VAS scores of the group mk were significantly lower than those of the group m in activity state (all P<0.05) and were not significantly different those of the group m at resting state (all P>0.05). The total amount of morphine consumed and the actual PCA button pressing times were significantly less in the group mk than in the group m (both P<0.05). The incidence rates of nausea, vomiting, and pruritus of the group mk were all significantly lower than those of the group m (all P<0.05). There were not significant differences in the incidence rates of dreaming and pseudoesthesia between these 2 groups. All the vital signs were stable in the 2 groups. The plasma beta-EP levels at the time point T1 of these 2 groups were both significantly higher than those at T0 (both P<0.05). The plasma beta-endorphin levels at T2-4 of the group mk decreased gradually from the level at T1 to the level at T0, and the plasma beta-endorphin levels of the group m rapidly decreased from the level at T0 to the T0 level and remained at this level to the 48 h after operation. CONCLUSION: The combination of small dose of ketamine with morphine provides optimal analgesia with low side-effect rate and little effect on the plasma beta-EP level.