[Establishment of PCR assays and genetic polymorphism analysis of genes encoding Clostridium perfringens ß2 toxin from different sources].

Objective: To establish and optimize PCR methods for the gene encoding of Clostridium perfringens ß2 toxin (cpb2) and atypical-cpb2 (aty-cpb2), analyze the epidemiological characteristics and genetic polymorphism of the cpb2 of Clostridium perfringens in 9 Chinese areas from 2016 to 2021. Methods: The cpb2 of 188 Clostridium perfringens strains were examined by PCR; the cpb2 sequences were acquired by whole-genome sequencing to analyze the genetic polymorphism. Using Mega 11 and the Makeblastdb tool, a phylogenetic tree, and cpb2-library based on 110 strains carrying the cpb2 were produced. Using the Blastn technique, a comparison was made to discover sequence similarity between consensus-cpb2 (con-cpb2) and aty-cpb2. Results: The specificity of PCR assay for the cpb2 and aty-cpb2 was verified. The PCR results for cpb2 amplification were highly consistent with the whole-genome sequencing approach (Kappa=0.946, P<0.001). A total of 107 strains from nine regions in China carried cpb2, 94 types A strains carried aty-cpb2, 6 types A strains carried con-cpb2, and 7 types F strains carried aty-cpb2. The nucleotide sequence similarity between the two coding genes was 68.97%-70.97%, and the similarity between the same coding genes was 98.00%-100.00%. Conclusions: In this study, a specific PCR method for cpb2 toxin was developed, and the previous PCR method for detecting aty-cpb2 was improved. aty-cpb2 is the primary gene encoding of ß2 toxin. There is a significant nucleotide sequence variance between the various cpb2 genotypes.

[Progress in research of Clostridium perfringens toxin].

Clostridium perfringens can produce many kinds of toxins and hydrolase, causing gas gangrene, enteritis and enterotoxemia in both human and animals. It is known that C. perfringens can produce more than 20 toxins and hydrolases. The different toxin types are associated with specific disease types. At present, molecular toxin-typing method by PCR has replaced the traditional serological typing method. In this study, we systematically summarize the types, basic characteristics, pathogenic mechanism and the relationship with disease of C. perfringens toxins to provide evidence for the establishment of rapid detection method, immune antigen screening, antibody preparation and research of related pathogenic mechanism.

Magnetic field effect on topological properties of Dirac semimetals PdTe2/PtTe2/PtSe2.

We investigated magnetic field effect on the topological properties of transition metal dichalcogenide Dirac semimetals (DSMs) PdTe2/PtTe2/PtSe2based on Wannier-function-based tight-binding (WFTB) model obtained from first-principles calculations. The DSMs PdTe2/PtTe2/PtSe2undergo a transition from DSMs into Weyl semimetals with four pairs of Weyl points (WPs) in the entire Brillouin zone by splitting Dirac points under external magnetic fieldB. The positions and energies of WPs vary linearly with the strength of theBfield under thec-axis magnetic fieldB. Under thea- andb-axisBfield, however, the positions of magnetic-field-inducing WPs deviate slightly from thecaxis, and theirkzcoordinates and energies change in a parabolic-like curve with the increasingBfield. However, the system opens an axial gap on theA-Γ axis, and the gap changes with the direction of theBfield when the out ofc-axisBfield is applied. When we further apply the magnetic field in theac,bc, andabplanes, the results are more diverse compared to the axial magnetic field. Under theacandbcplaneBfield, thekzand energies of WPs within angleθ= [0°, 90°] andθ= [90°, 180°] are mirror symmetrically distributed. The distribution of WPs shows broken rotational symmetry under theabplaneBfield due to the difference of non-diagonal part of Hamiltonian. Our theoretical findings can provide a useful guideline for the applications of DSM materials under external magnetic field in the future topological electronic devices.

Late gestational liver dysfunction and its impact on pregnancy outcomes.

OBJECTIVE: The aim of this study was to investigate the impacts of late gestational liver dysfunction and its impact on pregnancy outcomes. MATERIALS AND METHODS: The patients hospitalized for liver dysfunction in their late pregnancy between 2010-2012 were set as the observation group, and the pregnant women with normal liver function at the same period were randomly selected and set as the control group. The impacts towards the pregnancy outcomes were compared between these two groups and the impacts of different-degree transaminase increasing towards the pregnancy outcome were analyzed. RESULTS: The incidence rates of cesarean section, post-partum hemorrhage, fetal distress, premature birth, premature rupture of membranes (PROM) of the observation group and the transaminase-severely-increased group (the severe group) were higher, and the differences were statistically significant (p < 0.01 or < 0.05); while only the cesarean rate of the mild and moderate group was significantly different from the control group (p < 0.01 or < 0.05). The ratios of intrahepatic cholestasis in pregnancy (ICP), gestational hypertension + HELLP syndrome, acute fatty liver in pregnancy (AFLP) of the severe group were higher than the mild and moderate group, and the differences were statistically significant; the non-alcoholic fatty liver disease (NAFLD) group and the unknown cause group mainly showed a mildly increased transaminase; the distributions of viral hepatitis in pregnancy (VHP), post-viral-hepatitis-B cirrhosis, biliary tract disease, and infected toxic liver dysfunction in different-degree increased transaminase groups had no significant difference. CONCLUSIONS: Liver dysfunction in later pregnancy, especially with severe transaminase increase, might significantly increase the risk of adverse maternal events. The major causes of severe liver dysfunction in late pregnancy were ICP, gestational hypertensive disorders, and AFLP.

A new phase of phosphorus: the missed tricycle type red phosphorene.

We predict a new two-dimensional allotrope of phosphorus, which we call red phosphorene, by restructuring the segments of the previously proposed blue and black phosphorenes. Its atomic and electronic structures as well as the thermodynamic and dynamic stabilities are systematically studied by first-principles calculations. The results indicate that the red phosphorene is dynamically stable and possesses remarkably thermodynamical stability comparable to that of the black one. Because of the sp(3)-hybridization and the formation of a localized lone pair, red phosphorene is a semiconductor with an indirect band gap of about 1.96 eV, which can be effectively modulated by in-plane strains due to its wave-like configuration. We find that the red, black and blue phosphorenes show evident distinction in their layer thicknesses, surface work functions, and possible colors, based on which one can distinguish them in future experiments.

Effect of glutamine on intestinal barrier function following liver transplantation in rats.

OBJECTIVES: Glutamine is an important fuel for intestinal mucosal epithelial cells, and it promotes intestinal mucosal cell differentiation and proliferation. Most liver transplantation (LT) patients suffer from intestinal barrier dysfunction. Whether enteral glutamine supplementation has beneficial effects on intestinal barrier function following LT is not known. We investigated the effect of glutamine (Gln) supplementation on NF-κB and on the intestinal barrier in rats after an allogenic LT with concomitant immunosuppressive therapy. MATERIALS AND METHODS: Inbred Sprague-Dawley rats (n=40) receiving allogenic LT were randomly divided into Gln and control groups (n=20, each). Gln group rats were administered Gln (0.4 g/kg·day) by gastric infusion for 6 days, while control rats received saline. Ten rats from each group were sampled for basal parameters on the 3rd day, prior to LT. The remaining 10 from each group were sampled after receiving LT. Twenty inbred Sprague-Dawley rats were selected as donors. The 20 recipients underwent orthotopic LT after 3 days of treatment and were given immunosuppressive therapy for 6 days post-operation. They were euthanized for sample collection on the 7th day. NF-κB protein in the intestinal mucosa, portal plasma Gln, endotoxin and TNF-α levels, ileocecal sIgA content, bacterial translocation and mucosal ultrastructure were assessed. RESULTS: On the postoperative day 6, the Gln group had increased plasma Gln and ileocecal sIgA (secretory IgA). Gln group also showed improvement in mucosal microvilli structure and had reduced levels of intestinal mucosal NF-κB, portal endotoxin and TNF-α and decreased bacterial translocation as compared to the control group. CONCLUSIONS: Parenteral supplementation of glutamine ameliorated mucosal injury during allogenic LT, and improved intestinal barrier function. These findings suggest that glutamine supplementation may be an effective therapy to ensure successful recovery from liver transplantation.

L-arginine enhances arginine deiminase induced human lymphoma cell growth inhibition through NF-kBp65 and p53 expression in vitro.

OBJECTIVE: Arginine deiminase (ADI) and L-arginine (L-Arg) can act as anti-tumor agents in-vitro and in-vivo. However, the mechanism of ADI and L-Arg as anti-tumor agents has not been clearly shown. MATERIALS AND METHODS: With the goal of understanding the role of ADI and L-Arg in inhibition of cell growth, we used the Ramos human lymphoma cell line, which is known to be ADI-sensitive, and observed the p53 and NF-κBp65 protein expression after ADI and arginine treatment. After determining an optimal experimental ADI concentration (0.01 U/ml), we studied the effects of ADI treatment, when combined with different concentrations of L-arginine (control, ADI only, ADI with 10 mM/ml Arg, ADI with 30 mM/ml Arg, and ADI with 50 mM/ml Arg). An MTT assay was used to assess cell survival after treatment, Western blot analysis to determine the levels of the NF-κBp65, p53 and NO mediators and nitric oxide assays were used to determine nitrite levels. RESULTS AND CONCLUSIONS: L-arginine enhanced ADI-induced inhibited cell growth through expression of NF-κBp65 and p53 in a dose-dependent manner.

Non-covalent doping of graphitic carbon nitride with ultrathin graphene oxide and molybdenum disulfide nanosheets: an effective binary heterojunction photocatalyst under visible light irradiation.

A proof of concept integrating binary p-n heterojunctions into a semiconductor hybrid photocatalyst is demonstrated by non-covalent doping of graphite-like carbon nitride (g-C3N4) with ultrathin GO and MoS2 nanosheets using a facile sonochemical method. In this unique ternary hybrid, the layered MoS2 and GO nanosheets with a large surface area enhance light absorption to generate more photoelectrons. On account of the coupling between MoS2 and GO with g-C3N4, the ternary hybrid possesses binary p-n heterojunctions at the g-C3N4/MoS2 and g-C3N4/GO interfaces. The space charge layers created by the p-n heterojunctions not only enhance photogeneration, but also promote charge separation and transfer of electron-hole pairs. In addition, the ultrathin MoS2 and GO with high mobility act as electron mediators to facilitate separation of photogenerated electron-hole pairs at each p-n heterojunction. As a result, the ternary hybrid photocatalyst exhibits improved photoelectrochemical and photocatalytic activity under visible light irradiation compared to other reference materials. The results provide new insights into the large-scale production of semiconductor photocatalysts.

Regulation of apoptosis in human gastric cancer cell line SGC-7901 by L-arginine.

Aim: L-arginine (LArg) is an amino acid that has immunomodulating and anti-tumor effects. It is possible that anti-tumor effects of L-Arg are due to induction of apoptosis in tumor cells. The present study assessed anti-proliferating and pro-apoptotic effects of L-Arg in human gastric cancer cell line SGC7901. Methods: Cell proliferation was quantified by MTT assay. Apoptosis was assessed using flow cytometry and FITCAnnexinV/ propidium iodide staining. Expression and activation of proteins pertinent to apoptosis (Bcl2, surviving, p53, and XIAP) were studied using PCR, Western blot, and activity assays. Results: L-Arg significantly inhibited growth of SCG-7901 gastric cancer cells and down-regulated expression of anti-apoptotic gene Bcl-2 and survivin. By contrast, expression of p53 was upregulated by L-Arg. Conclusion: Regulation of apoptosis by L-Arg via down-regulation of anti-apoptotic proteins Bcl-2 and surviving, and up-regulation of pro-apoptotic protein p53 may represent the mechanism behind antitumor effects of L-Arg.

Zebrafish Noxa promotes mitosis in early embryonic development and regulates apoptosis in subsequent embryogenesis.

Noxa functions in apoptosis and immune system of vertebrates, but its activities in embryo development remain unclear. In this study, we have studied the role of zebrafish Noxa (zNoxa) by using zNoxa-specifc morpholino knockdown and overexpression approaches in developing zebrafish embryos. Expression pattern analysis indicates that zNoxa transcript is of maternal origin, which displays a uniform distribution in early embryonic development until shield stage, and the zygote zNoxa transcription is initiated from this stage and mainly localized in YSL of the embryos. The zNoxa expression alterations result in strong embryonic development defects, demonstrating that zNoxa regulates apoptosis from 75% epiboly stage of development onward, in which zNoxa firstly induces the expression of zBik, and then cooperates with zBik to regulate apoptosis. Moreover, zNoxa knockdown also causes a reduction in number of mitotic cells before 8 h.p.f., suggesting that zNoxa also promotes mitosis before 75% epiboly stage. The effect of zNoxa on mitosis is mediated by zWnt4b in early embryos, whereas zMcl1a and zMcl1b suppress the ability of zNoxa to regulate mitosis and apoptosis at different developmental stages. In addition, mammalian mouse Noxa (mNoxa) mRNA was demonstrated to rescue the arrest of mitosis when zNoxa was knocked down, suggesting that mouse and zebrafish Noxa might have similar dual functions. Therefore, the current findings indicate that Noxa is a novel regulator of early mitosis before 75% epiboly stage when it translates into a key mediator of apoptosis in subsequent embryogenesis.

Regulation of apoptosis in human gastric cancer cell line SGC-7901 by L-arginine.

AIM: L-arginine (L-Arg) is an aminoacid that has immunomodulating and antitumor effects. It is possible that antitumor effects of L-Arg are due to induction of apoptosis in tumor cells. The present study assessed antiproliferating and proapoptotic effects of L-Arg in human gastric cancer cell line SGC-7901. METHODS: Cell proliferation was quantified by MTT assay. Apoptosis was assessed using flow cytometry and FITC-Annexin-V/propidium iodide staining. Expression and activation of proteins pertinent to apoptosis (Bcl-2, surviving, p53, and XIAP) were studied using PCR, Western blot, and activity assays. RESULTS: L-Arg significantly inhibited growth of SCG-7901 gastric cancer cells and downregulated expression of antiapoptotic gene Bcl-2 and survivin. By contrast, expression of p53 was upregulated by L-Arg. CONCLUSION: Regulation of apoptosis by L-Arg via downregulation of antiapoptotic proteins Bcl-2 and surviving, and upregulation of proapoptotic protein p53 may represent the mechanism behind antitumor effects of L-Arg.

Fabrication of ordered NiO coated Si nanowire array films as electrodes for a high performance lithium ion battery.

Highly ordered NiO coated Si nanowire array films are fabricated as electrodes for a high performance lithium ion battery via depositing Ni on electroless-etched Si nanowires and subsequently annealing. The structures and morphologies of as-prepared films are characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. When the potential window versus lithium was controlled, the coated NiO can be selected to be electrochemically active to store and release Li+ ions, while highly conductive crystalline Si cores function as nothing more than a stable mechanical support and an efficient electrical conducting pathway. The hybrid nanowire array films exhibit superior cyclic stability and reversible capacity compared to that of NiO nanostructured films. Owing to the ease of large-scale fabrication and superior electrochemical performance, these hybrid nanowire array films will be promising anode materials for high performance lithium-ion batteries.

Magnetic and upconverted luminescent properties of multifunctional lanthanide doped cubic KGdF4 nanocrystals.

Lanthanide (Ln3+) doped KGdF4 (Ln=Yb3+, Er3+, Ho3+, Tm3+) nanocrystals with a mean diameter of approximately 12 nm were synthesized by a hydrothermal method using oleic acid as a stabilizing agent at 180 °C. The nanocrystals crystallize in the cubic phase as α-NaGdF4. When excited by a 980 nm laser, these Ln3+ doped nanocrystals exhibit multicolor up-conversion (UC) emissions in red, yellow, blue and white. The calculated color coordinates demonstrate that white UC emission (CIE-X=0.352, CIE-Y=0.347) can be obtained by varying the dopant concentrations in the Yb3+/Ho3+/Tm3+ triply-doped nanocrystals to yield different RGB emission intensities. The measured field dependence of magnetization (M-H curves) of the KGdF4 nanocrystals shows their paramagnetic characteristics that can be ascribed to the non-interacting localized nature of the magnetic moment of Gd3+ ions. Moreover, low temperature thermal treatment can enhance UC properties, magnetization and magnetic mass susceptibility of Ln3+ doped KGdF4 nanocrystals. The multifunctional Ln3+ doped KGdF4 nanocrystals have potential applications in color displays, bioseparation, and optical-magnetic dual modal nanoprobes in biomedical imaging.

Sharp corners in the cross section of ultrathin Si nanowires.

We have determined stable geometries for pristine Si nanowires grown along their 100 axis through systematic density functional studies. Strikingly, Si nanowires with diameters smaller than 1.7 nm prefer a shape that has a square cross section. This stems from dimerization between corner atoms and also from benign reconstruction patterns that maximally saturate Si dangling bonds.

[Crystal and molecular structure of the antimalarial agent alpha-(dibutylaminomethyl)-2, 7-dichloro-9-(p-chlorobenzylidene)-4- fluorenemethanol(benflumetol)].

The three-dimensional crystal and molecular structure of benflumetol(I), alpha-(dibutylaminomethyl)-2, 7-dichloro-9-(p-chlorobenzylidene)-4-fluorenemethanol, was determined by X-ray crystallography and compared with the crystal structures of the cinchona alkaloids. The aromatic rings of fluorene-phenyl system of benflumetol are twisted from each other by 52.8 degrees. The torsion angle of N-C-C-O of benflumetol is 47.6 degrees. The intramolecular aliphatic N-O distance in benflumetol is 2.709A, which is close to the N-O distance found in antimalarial cinchona alkaloids. Benflumetol contains an intramolecular hydrogen bond between the aliphatic nitrogen and oxygen atoms, no intermolecular hydrogen bond was found, which is different from the known amino alcohol antimalarials.

[Synthesis and antimalarial activities of fluorenemethanols].

For the purpose of improving the oral antimalarial activities of the fluorenemethanols (reported by us in previous articles) which were less effective by oral than by subcutaneous administration, 24 alpha-(alkylaminomethyl)-2, 7-dichloro-9-substituted benzylidene-4-fluorenemethanols (III) were synthesized. The results of preliminary screenings demonstrated that five compounds (No. 1-4, 8) exhibited significant antimalarial activities against Plasmodium berghei NK65 strain in mice by oral administration, at dose of 6.25 mg.kg-1.d-1 x 3 with suppressive rate of 100%. Further evaluation of these 5 compounds showed that 4 of them (No. 1-4) were superior to chloroquine in parallel tests, their ED50 and ED90 were 1.0, 1.6; 0.6, 0.9; 0.7, 1.5 and 0.8, 1.6 mg.kg-1.d-1 x 3 respectively, while the ED50 and ED90 of chloroquine were 1.9 and 2.9 mg.kg-1. d-1 x 3 respectively; one compound (No 8) was equal to chloroquine, its ED50 and ED90 were 1.5 and 3.2 mg.kg-1.d-1 x 3 respectively. Further assessment of these 4 compounds are in progress.

[Synthesis of 4-methyl-5-substituted phenoxy-primaquine analogues and preliminary evaluation on their antimalarial activity].

On basis of our previous work, seven 4-methyl-5-substituted phenoxy-6-methoxy-8-(1-methyl-4-amino-butylamino)-quinolines (II2-8) were synthesized and their antimalarial activities were preliminarily evaluated. The target compounds were prepared from 2-nitro-4-methoxy-5-bromo-acetanilide as previously described. The structures of II2-8 and all of the unknown intermediates were confirmed by elementary and spectral analyses. Preliminary biological evaluation revealed that all of II2-8 exhibited significant blood schizonticidal activity and were 4-8 times as effective as primaquine in causal prophylactic test in mice.

[Synthesis of 2-methyl-5-substituted phenoxy-primaquine and antimalarials activity].

In searching for efficient, safe and radically curative agent and causal prophylactics for malaria, seven 2-methyl-5-substituted phenoxy-6-methoxy-8-(1-methyl-4-aminobutylamino)-quinolines (II1-7) were synthesized and their antimalarial activities were compared with the corresponding 4-methyl substituted derivatives of primaquine. The starting material, 2-nitro-4-methoxy-5-bromo-acetanilide (III), was prepared from p-methoxy aniline through acetylation, bromination and nitration. III was then condensed with substituted phenols in the presence of potassium carbonate. The condensed products were subsequently hydrolyzed with dilute alcoholic hydrochloric acid to yield 2-nitro-4-methoxy-5-substituted phenoxy-aniline (V) which underwent Skraup's reaction with 2-butenal to provide the key intermediates 2-methyl-5-substituted phenoxy-6-methoxy-8-nitroquinolines (VI). These 8-nitroquinoline derivatives were reduced to 8-aminoquinoline derivatives (VII). The latter were condensed with 4-bromo-1-phthalimido-pentane and then hydrolyzed with hydrazine hydrate, the final products were obtained as oxalate or succinate. The structure of the target compounds and unknown intermediates were confirmed by elementary and spectral analysis. Primary biological evaluation showed that all compounds II1-7 were much less active than the 4-methyl substituted derivatives and slightly less active than primaquine in both causal prophylactic test against Plasmodium yoelii and suppressive antimalarial test against P. berhei.