羟基磷灰石复合二氧化锆泡沫陶瓷的理化性能与细胞化性能

背景:研究已证实羟基磷灰石/二氧化锆泡沫陶瓷材料具有良好的促骨再生能力,但关于其遗传毒性还未见报道。目的:检测羟基磷灰石/二氧化锆泡沫陶瓷材料的孔隙率与抗压强度,以及遗传毒性与细胞毒性,探索人工诱导多能干细胞来源间充质干细胞在羟基磷灰石/二氧化锆泡沫陶瓷材料上的成骨分化能力。方法:在添加造孔剂的情况下,采用高温烧结法制备羟基磷灰石/二氧化锆泡沫陶瓷材料,检测其孔隙率与抗压强度。采用鼠伤寒沙门氏菌回复突变实验检测羟基磷灰石/二氧化锆泡沫陶瓷材料的遗传毒性。分别采用羟基磷灰石/二氧化锆泡沫陶瓷材料浸提液(实验组)、苯酚溶液(阳性对照组)、生理盐水(阴性对照组)培养L929细胞,24h后,采用CCK-8法检测细胞毒性。将人工诱导多能干细胞来源间充质干细胞接种于羟基磷灰石/二氧化锆泡沫陶瓷材料上,培养第3,7,10,14天,检测细胞碱性磷酸酶分泌量;培养第14天,免疫组织化学法检测复合体细胞Ⅰ型胶原表达,扫描电镜观察细胞黏附情况。结果与结论:①羟基磷灰石/二氧化锆泡沫陶瓷材料的孔隙率为(76.72±0.75)%,抗压强度为(11.60±1.35) MPa;②鼠伤寒沙门氏菌回复突变实验显示,羟基磷灰石/二氧化锆泡沫陶瓷材料的代谢产物无致突变、无致癌作用;③CCK-8实验显示,实验组的细胞存活率与阴性对照组比较差异无显著性意义(P> 0.05),但明显高于阳性对照组(P <0.05);④随着培养时间的延长,细胞碱性磷酸酶分泌量逐渐增加,各时间点间两两比较差异均有显著性意义(P <0.05);⑤培养第14天,大量人工诱导多能干细胞来源间充质干细胞均匀分布于羟基磷灰石/二氧化锆泡沫陶瓷材料表面,细胞形态及生长良好,并且Ⅰ型胶原表达较多;⑥结果表明,羟基磷灰石/二氧化锆泡沫陶瓷材料具备一定的抗压能力,无致突变作用和细胞毒性,可促进人工诱导多能干细胞来源间充质干细胞的成骨分化。

水产健康养殖要重视生石灰的应用

生石灰学名氧化钙,为白色或灰白色硬块,易吸水。生石灰遇水生成强碱性氢氧化钙,使池水p H值急剧上升,能快速溶解病原体细胞蛋白质膜,有较好的防治鱼虾蟹等水产养殖动物病害的作用。生石灰在水产健康养殖中的应用,具有安全、环保、副作用小等诸多优点,但由于在使用时相对于＂便捷＂药物比较费力费工,

Flow Cytometric Evidence for Hydroxyl Radical-induced Apoptosis in Tobacco Protoplasts

Protoplasts prepared from tobacco (Nicotiana tabacum L., cultivar BY-2) suspension cells have similar morphological characteristics to those in animal cells. The hallmarks of apoptosis such as condensation and peripheral distribution of nuclei, TUNEL positive reaction, and DNA ladders were observed when tobacco protoplasts were treated with the hydroxyl radical generating system (1.0 mmol/L FeSO4/0.5 mmol/L H2O2). In animals, the loss of transmembrane potential (DeltaPsi(m)) and the exposure of phospholipid phosphatidylserine (PS) are believed to be the main apoptosis events. To test whether these significant processes take place in plants, flow cytometry was used to detect annexin V binding and changes in DeltaPsi(m). Results showed that the PS turned out from inner membrane and DeltaPsi(m) gradually decreased during the apoptosis. All these apoptotic characteristics proved that hydroxyl radicals can cause typical programmed cell death (PCD) in tobacco protoplasts and this design can be served as an effective experiment system to explore the mechanism of plant apoptosis.

Studies on Parameters Affecting Embryogenesis of Protoplasts Isolated from Suspension of Embryogenic Cells in Loblolly Pine

Protoplasts of embryogenic suspension cells of loblolly pine (Pinus taeda L).were isolated at exponential growth stage.Influences of various concentrations of basal medium,levels of BA,and concentrations of inositol on the differentiation of embryonal suspensor mass (ESM),early stage somatic embryos (ESE) ,and lae stage somatic embryos (LSE) were investigated .A study of the effect of various concentrations of LP basal medium sowed that the optimal basal medium concentration of ESM,ESE,and LSE differentiation was 1.25 LP medium.The effects of various levels of BA and inositol showed that the optimal concentrations of BA for the formation of ESM,ESE and LSE were 4 mg/L ,2mg/L and 1mg/L,respectively ,and the optimal concentrations of inositol for the ESM ,ESE and LSM formation were 400mg/L,800mg/L and 1,200mg/L,respectively.

Alterations of red blood cell immunoadherence function in hepatitis B patients

AIMS To investigate the alterations of RBC immunoadherence function in patients with various hepatitis B. METHODS RBCC3bRR,RBCICRR and serum CIC levels were measured in 42 patients with acute and chronic hepatitis B at ac- tive and convalescence stages. RESULTS RBCC3bRRs at the active/acute stage of various hepatitis were decreased.They were 13,54%±5,23% in AH, 7.61%±4.12% in AFH,and 16.18%±6.10% in CH, respectively,all of which were lower than those in normal persons (18.12%±3.91% ).At the quiescent/recovery stage of various hepatitis,the RBCC3bRRs were increased significantly.The changes of RBCICRR and serum CIC level were contrary to those of RBCC3bRR. CONCLUSIONS RBC immunoadherence function is decreased in acute and chronic hepatitis.The decrease is in direct proportion to the severity of the diseases.

Anti-CD132 Monoclonal Antibodies Inducing T Cells Apoptosis after Alloantigen Stimulation and Its Possible Clinical Applications

Aim To investigate the mechanism of anti-CD132 monoclonal antibodies (mAbs)inhibiting T cells proliferation in vitro, and their potential values for clinical use. MethodsBALB/c and C57BL/6 mice splenocytes were harvested for two-ways mixed lymphocyte culture (MLC).Anti-CD132 mAbs (final concentration 100 mg·L^(-1)) were added in MLC on day 0 (group 1) or day 3(group 2). Fluorescence activated cell sorting (FACS) was used to measure the proliferation(carboxy-fluorescein dia cetate, succinimidyl ester, CFSE), apoptosis of T cells (PE-CD3,FTTC-annexin-v), and cell cycle (pro-pidium iodide stain) . The expression of survivin in T cellswas detected by immunochemical stai-ning. Re-sults Multi-generation CFSE-labeled splenocytes werefound dividing and their fluorescent strength decreased in MLC. There was no noticeable change influorescent intensity in group 1 and group 2. On day 3, apoptosis induced by anti-CD132 mAbs wasdetected in part of T cells, but was not detected in the former two days in group 1. In group 2, thenumber of cells in M phase (activated T cells) decreased and apoptot-ic cells increased on day 4.The phenomena were not observed in control group (P < 0.01). Expression of survivin in T cells wasdetected in control group but not in groups 1 and 2. Conclusion Blockade of CD132 signaling pathwayinhibits T cell proliferation in vitro by means of inducing activated alloreactive T cell apoptosisbut not the resting T cells. Anti-CD132 mAbs may be candidates for clinical applications.

Interactions between mycoplasma lipid-associated membrane proteins and the host cells

Mycoplamas are a group of wall-less prokaryotes widely distributed in nature, some of which are pathogenic for humans and animals. There are many lipoproteins anchored on the outer face of the plasma membrane, called lipid-associated membrane proteins (LAMPs). LAMPs are highly antigenic and could undergo phase and size variation, and are recognized by the innate immune system through Toll-like receptors (TLR) 2 and 6. LAMPs can modulate the immune system, and could induce immune cells apoptosis or death. In addition, they may associate with malignant transformation of host cells and are also con-sidered to be cofactors in the progression of AIDS.

Secretory Expression of E2 Main Antigen Domain of CSFV C Strain and the Establishment of Indirect ELISA Assay

The sequence encoding an E2 main antigen glycoprotein of the C strain of classical swine fever virus (CSFV) was highly expressed in the host cell E. coli BL21–CodonPlus (DE3)–RIL using the pGEX-4T-1 expression vector and the soluble recombinant product was purified with Glutathione Sepharose TM4B by centrifugation. The soluble recombinant protein showed good immune reactions and was confirmed by Western blot using anti-CSFV-specific antibodies. Then an indirect ELISA with the purified E2 protein as the coating antigen was established to detect antibody against CSFV. The result revealed that the optimal concentration of coated antigen was 0.6 μg/well and the optimal dilution of serum was 1:80. The positive cut-off value of this ELISA assay was OD tested serum / OD negative serum≥2.1. The E2-ELISA method was evaluated by comparison with the indirect hemagglutination test (IHAT). When a total of 100 field serum samples were tested the sensitivity and specificity were 90.3% and 94.7% respectively. Specificity analysis showed that there were no cross-reactions between BVD serum and the purified E2 protein in the E2-ELISA.

Bile acids as endogenous etiologic agents in gastrointestinal cancer

Bile acids are implicated as etiologic agents in cancer of the gastrointestinal (GI) tract, including cancer of the esophagus, stomach, small intestine, liver, biliary tract, pancreas and colon/rectum. Deleterious effects of bile acid exposure, likely related to carcinogenesis, include: induction of reactive oxygen and reactive nitrogen species; induction of DNA damage; stimulation of mutation; induction of apoptosis in the short term, and selection for apoptosis resistance in the long term. These deleterious effects have, so far, been reported most consistently in relation to esophageal and colorectal cancer, but also to some extent in relation to cancer of other organs. In addition, evidence is reviewed for an association of increased bile acid exposure with cancer risk in human populations, in specific human genetic conditions, and in animal experiments. A model for the role of bile acids in GI carcinogenesis is presented from a Darwinian perspective that offers an explanation for how the observed effects of bile acids on cells contribute to cancer development.

Procedure for preparing peptide-major histocompatibility complex tetramers for direct quantification of antigen-specific cytotoxic T lymphocytes

AIM： To establish a simplified method for generating peptide-major histocompatibility complex （MHC） class I tetramers.METHODS： cDNAs encoding the extracellular domain of human lymphocyte antigen （HLA）-A＊0201 heavy chain （A2） and β2-microglobulin （132m） from total RNA extracted from leukocytes of HLA-A2＋ donors were doned into separate expression vectors by reverse transcription-polymerase chain reaction. The recombinant A2 and 132m proteins were expressed in ~/a oo/i^uain BL21（DE3） and recovered from the inclusion body fraction. Soluble A2 proteins loaded with specific antigen peptides were refolded by dilution from the heavy chain in the presence of light chain 132m and HLA-A2-restricted peptide antigens. The refolded A2 monomers were biotinylated with a commercial biotinylation enzyme （BirA） and purified by low pressure anion exchange chromatography on a Q-Sepharose （fast flow） column.The tetramers were then formed by mixing A2 monomers with streptavidin-PE in a molar ratio of 4：1. Flow cytometry was used to confirm the expected tetramer staining of CD8^＋ T cells.RESULTS： Recombinant genes for HLA-A＊0201 heavy chain （A2） fused to a BirA substrate peptide （A2-BSP） and mature β2m from HLA-A2＋ donor leukocytes were successfully doned and highly expressed in E. coli, Two soluble monomeric A2-peptide complexes were reconstituted from A2-BSP in the presence of 132m and peptides loaded with either human cytomegalovirus pp65495-503 peptide （NLVPMVATV,NLV; designated as A2-NLV） or influenza virus matrix protein Mp58-66 peptide （GILGFVFTL, GIL; designated as A2-GIL）. Refolded A2-NLV or A2-GIL monomers were biotinylated and highly purified by single step anion exchange column chromatography. The tetramers were then formed by mixing the biotinylated A2-NLV or A2-GIL monomers with streptavidin-PE, leading to more than 80% multiplicationas revealed by SDS-PAGE under non-reducing, unboiled conditions. Flow cytometry revealed that these tetramers could specifically bind to CD8^＋ T cells from a HLA-A2^＋ donor,but failed to bind to those from a HLA-A2- donor.CONCLUSION： The procedure is simple and efficient for generating peptide-MHC tetramers.

Enemy at the gates： dendritic cells and immunity to mucosal pathogens

Dendritic cells （DC） are diverse and specialized hematopoietic cells serving as an essential bridge between innate and adaptive immunity. DC exist in all lymphoid and nonlymphoid organs and are amongst the first responders to infection at epithelial surfaces including mucosal tissues. DC of the lung, gut, and vaginal mucosa display different phenotypes and functions reflecting each unique tissue and, in contrast to their counterparts in spleen and lymph nodes, are constantly exposed to both harmful and benign factors of their environments. Mucosal DC recognize and respond to pathogens through engagement of pattern recognition receptors, and activated DC migrate to draining lymph nodes to induce adaptive immune responses. The specialized function of DC aids in the induction of immunity and pathogen control at the mucosa. Such specialization includes the potent antiviral interferon response of plasma- cytoid DC to viral nucleic acids, the ability of mucosal DC to capture organisms in the gut lumen, the capacity of DC to cross-present antigen from other infected cells, and the ability of mucosal DC to initiate lgA class switching in B cells. DC plasticity is also critical in the immune response to mucosal pathogens, as DC can respond to the microen- vironment and sense pathogen-induced stress in neighboring epithelial cells. Finally, DC interact with each other through crosstalk to promote antigen presentation and T-cell immunity. Together, these processes condition mucosal DC for the induction of a tailored immune response to pathogens.

MEKK1, MKK1/MKK2 and MPK4 function together in a mitogen-activated protein kinase cascade to regulate innate immunity in plants

Mitogen-activated protein kinase （MAPK） cascades play important roles in regulating plant innate immune responses. In a genetic screen to search for mutants with constitutive defense responses, we identified multiple alleles of mpk4 and mekkl that exhibit cell death and constitutive defense responses. Bimolecular fluorescence complemen- tation （BiFC） analysis showed that both MPK4 and MEKK1 interact with MKK1 and MKK2, two closely related MAPK kinases, mkkl and mkk2 single mutant plants do not have obvious mutant phenotypes. To test whether MKK1 and MKK2 function redundantly, mkkl mkk2 double mutants were generated. The mkkl mkk2 double mutant plants die at seedling stage and the seedling-lethality phenotype is temperature-dependent. Similar to the mpk4 and mekkl mutants, the mkkl mkk2 double mutant seedlings accumulate high levels of H202, display spontaneous cell death, constitutively express Pathogenesis Related （PR） genes and exhibit pathogen resistance. In addition, activation of MPK4 by fig22 is impaired in the mkkl mkk2 double mutants, suggesting that MKK1 and MKK2 function together with MPK4 and MEKK1 in a MAP kinase cascade to negatively regulate innate immune responses in plants.

Influence of Bioelectret Materials on cell Culture

The aim of this work is to study the effects of the electret property of natural biopolymers (such as collagen) on tissue repair. Type I collagen was prepared from pigskin,and polarized by using the TSDC (thermally stimulated depolarization current) technique. The polarized materials are used for cell culture. and then the cell growth curve is drawn. It was found that the polarized biomaterials accelerated cell differentiation. which indicates that they may be applied in the biomedical field.

CLINICAL EVALUATION OF FOUR RECOMBINANT TREPONEMA PALLIDUM ANTIGEN-BASED RAPID TESTS IN THE DIAGNOSIS OF SYPHILIS

Objective To assess the sensitivity, specificity, and feasibility of 4 recombinant Treponema pallidum antigenbased rapid tests in the diagnosis of syphilis. Methods A total of 970 outpatients were selected from the Sexually Transmitted Diseases Centre of Peking Union Medical College Hospital. Venous blood was collected and serum was extracted. T. paUidum antibodies in whole blood, anticoagulant whole blood, and serum were detected using 4 recombinant T. pallidum antigen-based rapid tests. T. pallidum haemagglutination test （TPHA） was considered as the gold standard for the detection of T. pallidum specific antibodies in serum. The sensitivities and specificities of four methods were analyzed. Results The sensitivities and specificities of Abbott Determine Syphilis TP test, SD-BIOLINE Syphilis 3.0 test, VISITECT-SYPHILIS test, and Syphicheck-WB test for serum specimens were 100% and 98. 9%, 95.7% and 98.0%, 94.6% and 98.2%, 68.1% and 98.9% ; for whole blood were 74. 1% and 99. 5%, 87.9% and 99.4% , 73.2% and 99.7%, 64. 7% and 99.7%. The observed sensitivities of the 4 rapid diagnosis tests were not significantly different with TPHA （ P 〉 0.05 ）. Conclusions The 4 rapid tests show good performance and characteristics in the diagnosis of syphilis. Furthermore, they are more sensitive for serum specimens than whole blood.

Caspase Work Model During Pathogen Infection

Caspases are an evolutionarily conserved family of aspartate-specific cystein-dependent proteases with essential functions in apoptosis and normally exist in cells as inactive proenzymes. In addition to the inflammatory caspases, the initiator and effector caspases have been shown to have an important role in regulating the immune response, but are involved in different ways. We give a brief introduction on the benefit of apoptosis on the clearance of invasive pathogens, and the caspase functions involved in the immune response. Then we construct a working model of caspases during pathogen invasion. A detailed description of the three modes is given in the discussion. These three modes are regulated by different inhibitors, and there may be a novel way to treat intracellular pathogen and autoimmune diseases based on the specific inhibitors.

Enhancing rice resistance to fungal pathogens by transformation with cell wall degrading enzyme genes from Trichoderma atroviride

Three genes encoding for fungal cell wall degrading enzymes (CWDEs), ech42, nag70 and gluc78 from the biocontrol fungus Trichoderma atroviride were inserted into the binary vector pCAMBIA1305.2 singly and in all possible combinations and transformed to rice plants. More than 1800 independently regenerated plantlets in seven different populations (for each of the three genes and each of the four gene combinations) were obtained. The ech42 gene encoding for an endochitinase increased resistance to sheath blight caused by Rhizoctonia solani, while the exochitinase-encoding gene, nag70, had lesser effect. The expression level of endochitinase but exochitinase was correlated with disease resistance. Nevertheless, exochitinase enhanced the effect of endochitinase on disease resistance when the two genes co-expressed in transgenics. Resistance to Magnaporthe grisea was found in all kinds of regenerated plants including that with single gluc78. A few lines expressing either ech42 or nag70 gene were immune to the disease. Transgenic plants are being tested to further evaluate disease resistance at field level. This is the first report of multiple of expression of genes encoding CWDEs from Trichoderma atroviride that result in resistance to blast and sheath blight in rice.

Negative feedback regulation of cellular antiviral signaling by RBCKl-mediated degradation of IRF3

Viral infection causes host cells to produce type I interferons （IFNs）, which are critically involved in viral clearance. Previous studies have demonstrated that activation of the transcription factor interferon regulatory factor （IRF）3 is essential for virus-triggered induction of type I IFNs. Here we show that the E3 ubiquitin ligase RBCC protein interacting with PKC1 （RBCK1） catalyzes the ubiquitination and degradation of IRF3. Overexpression of RBCK1 negatively regulates Sendai virus-triggered induction of type I IFNs, while knockdown of RBCK1 has the opposite effect. Plaque assays consistently demonstrate that RBCKI negatively regulates the cellular antiviral response. Furthermore, viral infection leads to induction of RBCK1 and subsequent degradation of IRF3. These findings suggest that the cellular antiviral response is controlled by a negative feedback regulatory mechanism involving RBCKl-mediated ubiquitination and degradation of IRF3.

A critical role of PUMA in maintenance of genomic integrity of murine spermatogonial stem cell precursors after genotoxic stress

Neonatal gonocytes are precursors of spermatogonial stem cells. Preserving their integrity by elimination of damaged germ cells may be crucial to avoid the transmission of genetic alterations to progeny. Using 7-irradiation, we investigated by immunohistochemistry, flow cytometry and real-time PCR components of the death machinery in neonatal gonocytes. Their death was correlated with caspase 3 activation but not with AIF translocation into the nu- cleus. The in vivo contribution of both the extrinsic and the intrinsic pathways was then investigated. We focused on the roles of TRAIL/Death Receptor 5 （DR5） and PUMA. Our results were validated using knockout mice. Whereas DR5 expression was upregulated at the cell surface after radiation, caspase 8 was not activated. However, we detected caspase 9 cleavage associated with cytochrome c release. In mice deficient for PUMA, radiation-induced gonocyte apoptosis was reduced, whereas invalidation of TRAIL had no effect. Overall, our results show that genotoxic stressinduced apoptosis of gonocytes is caspase-dependent and involves almost exclusively the intrinsic pathway. Furthermore, PUMA plays a critical role in the maintenance of genomic integrity of spermatogonial stem cell precursors.

Pivotal molecules of MHC I pathway in human primary hepatocellular carcinoma

AIM: To investigate the expression of several important molecules involved in major histocompatibility complex (MHC) class I presentation pathway in primary hepatocellular carcinoma (HCC), and to determine whether cytotoxic T lymphocyte (CTL) vaccine therapy was suitable for HCC. METHODS: Labeled streptavidin biotin(LSAB) method of immunohisto-chemistry was used to study 33 HCC tissue specimens. RESULTS: Most HCC tissues and adjacent histological normal hepatocytes expressed HLA-I antigens,TAP,and B7, expression of B7 was especially strong,and there was no significant difference between them (P>0.05). CONCLUSION: The MHC class I presentation pathway in primary hepatocellular carcinoma may not be abnormal or dysfunctional,and CTL could kill these tumor cells. Thus, it is suitable and practicable to design and construct CTL vaccine against HCC.

Overexpression of the receptor tyrosine kinase EphA4 in human gastric cancers

AIM: To clarify the expression and role of Ephrin receptor A4 (EphA4) in gastric cancer in relation to clinicopathological characteristics and the expression of fibroblast growth factor receptor 1 (FGFR1) and ephrin ligands. METHODS: Eleven gastric carcinoma cell lines, 24 paired surgical fresh specimens of gastric adenocarcinoma and adjacent nontumor tissue, 74 conventional formalin-fixed, paraffin-embedded tumor specimens, and 55 specimens spotted on tissue microarray (TMA) were analyzed. Reverse transcription-PCR (RT-PCR), real-time RT-PCR, immunohistochemistry, and cell growth assays were performed. RESULTS: Overexpression of EphA4 mRNA expres-sion was observed in 8 (73%) of 11 gastric cancer cell lines and 10 (42%) of 24 gastric cancer tissues. Over-expression of EphA4, analyzed by immunohistochemistry, was observed in 62 (48%) of 129 gastric cancer tissues. EphA4 overexpression, at the protein level, was significantly associated with depth of invasion and recurrence. EphA4 overexpression was also correlated with FGFR1 overexpression. Patients with EphA4-positive cancer had significantly shorter overall survival periods than did those with EphA4-negative cancer (P = 0.0008). The mRNAs for ephrin ligands were coexpressed in various combinations in gastric cancer cell lines and cancer tissues. Downregulation of EphA4 expression by siRNA in EphA4-overexpressing gastric cancer cell lines resulted in a significant decrease in cell growth. CONCLUSION: Our results suggest that overexpres-sion of EphA4 plays a role in gastric cancer.