Maspin expression and its clinicopathological significance in tumorigenesis and progression of gastric cancer

AIM:To investigate maspin expression in tumorigenesis and progression of gastric cancer and to explore its relevant molecular mechanisms.METHODS:Formalin-fixed and paraffin-embedded tissues from normal mucosa (n=182), dysplasia (n=69), cancer (n=l13) of the stomach were studied for maspin expression by immunohistochemistry. Microvessel density (MVD) in gastric cancer was labeled using anti-CD34 antibody. Maspin expression was compared with clinical parameters and MVD of tumors. Caspase-3 expression was also detected in gastric carcinoma by immunohistochemistry. The relationship between Caspase-3 and maspin expression was concerned as well.RESULTS:The positive rates of maspin expression were 79.8% (145/182), 75.4%(52/69) and 50.4%(57/113) in normal mucosa, dysplasia and cancer of the stomach,respectively.Cancer less frequently expressed maspin than normal mucosa and dysplasia (P<0.05).Maspin expression showed a significantly negative association with invasive depth, metastasis, Lauren's and Nakamura's classification (P<0.05),but not with tumor size, Borrmann's classification,growth pattern or TNIVl staging (P>0.05). The positive rate of Caspase-3 was significantly lower in gastric cancer than in normal gastric mucosa (P<0.05,32.7% vs 50.4%). It was noteworthy that maspin expression was negatively correlated with MVD, but positively correlated with expression of Caspase-3 in gastric cancer (P<0.05).CONCLUSION:Down-regulated maspin expression is a late molecular event in gastric carcinogenesis. Reduced expression of maspin contributes to progression of gastric cancer probably by inhibiting cell adhesion, enhandng cell mobility,decreasing cell apoptosis and facilitating angiogenesis.Additionally altered expression of maspin underlies the molecular mechanism of differentiation of gastric cancer and supports the different histogenetic pathways of intestinal and diffuse gastric cancers. Maspin expression can be considered as an effective and objective marker to reveal biological behaviors of gastric cancer.

New mutation points in 23S rRNA gene associated with Helicobacter pyloriresistance to clarithromycin in northeast China

AIM: TO investigate the resistance rate of Helicobacter pylori(H pylori) to clarithromycin, metronidazole, amoxicillin and tetracycline to guide clinical practice, and to study the mechanism of Hpylori resistant to clarithromycin. METHODS: Thirty Hpyloristrains were isolated from the mucosa of peptic ulcer, gastric tumor and chronic gastritis patients, then the minimal inhibitory concentration (MIC) to clarithromycin, metronidazole, amoxicillin and tetracycline was evaluated by E-test method. The sequence analysis of PCR fragments was conducted in 23S rRNA gene of H pylori resistant to clarithromycin to get the resistance mechanism of the bacteria. RESULTS: Among 30 Hpyloristrains, 7 cases were resistant to clarithromycin, 12 to metronidazole, 2 to tetracycline and no strain was found to be resistant to amoxicillin. The resistance rates were 23.3%, 40%, 6.7% and 0%, respectively. Three new mutation points were found to be related to the clarithromycin resistance in Hpyloriisolates, which were G2224A, C2245T and T2289C. CONCLUSION: In northeast China, H pylori shows high resistance to metronidazole, while sensitive to amoxicillin. The mechanism of resistance to clarithromycin may be related to the mutation of G2224A, C2245T and T2289C in the 23S rRNA gene.

Molecular Epidemiological Analysis of Echovirus 19 Isolated From an Outbreak Associated With Hand, Foot, and Mouth Disease (HFMD) in Shandong Province of China

To elucidate the genetic characterization and molecular epidemiological features of Echovirus 19 （El9） isolates collected from an outbreak associated with hand, foot and mouth disease （HFMD） in Tai＇an city of Shandong Province of China from July to September, 2003. Methods Thirty seven Echovirus 19 isolates were isolated from stool specimens and throat swabs collected during the outbreak, then major capsid （VP1） genomic sequence was determined, and phylogenetic tree was done based on the VP1 sequences among these 37 and other El9 viruses deposited in the Genbank. Also a representative strain named CHN-SD03-TN12 was selected for sequencing of 5′-untranslated regions （5′-UTR）. Results The identity rate was about 98.9%-100% among all these 37 El9 viruses. The genetic relationships between these 37 El9 isolates and other strains reported were also depicted. The identity rate was about 78.4%-78.9% compared with El9 reference strain Burke. The substitutions in the sequence of 5′-UTR resulted in changes in the conjectural properties of 5′-UTR of El9 viruses. Condusion The genetic features of El9 viruses isolated during the outbreak in Shandong Province in 2003 may be associated with a genetic and antigenic drift that changes the virulence of the Shandong isolates, but the molecular changes in Shandong El9 viruses contributing to their phenotype remain to be further illuminated. However, the sequences described in this paper substantiate the changes taken place in capsid VPI and 5′UTR regions. These substitutions may contribute to their tropism and virulence, and play a significant role in pathogenesis and clinical manifestations of the disease.

Polymorphisms of interleukin-1B and interleukin-1 receptor antagonist genes in patients with chronic hepatitis B

AIM：To investigate the relationships between polymorphisms of interleukin-lB (IL-1B) promoter region -511CLT and interleukin-1 receptor antagonist gene (IL-1RN) and susceptibility to chronic hepatitis B in Chinese population. METHODS: Genomic DNA was extracted from the peripheral blood of 190 patients with chronic hepatitis B and 249 normal controls and then subjected to polymerase chain reaction (PCR) amplification. The PCR products were digested by restriction endonuclease AvaI. The products of digestion were subjected to 20 g/L gel electrophoresis and ethidium bromide staining. RESULTS: The frequencies of IL-1B (-511) genotypes CC, CT and TT in patients with chronic hepatitis B were 23.7%, 49.5% and 26.8%, while 26.1%, 47.4% and 26.5% respectively in controls. The results showed that there was no significant difference in the frequencies of alleles or genotypes in IL-1B between patients with chronic hepatitis B and controls. The distributions of IL-1B (-511) genotype CC were significantly different between the two subgroups (HBV-DNA ≤1×10^3 copies/mL as subgroup I, HBV-DNA> 1×10^3 copies/mL as subgroup Ⅱ) of chronic hepatitis B (P=0.029). Only four of the five kinds of polymorphism (1/1, 1/2, 2/2 and 1/4) were found in this study. The frequencies of IL-1RN genotypes 1/1, 1/2, 2/2 and 1/4 were 88.9%, 9.0%, 0.5% and 1.6% in patients with chronic hepatitis B respectively, while were 81.1%, 16.9%, 0.4% and 1.6% respectively in controls. The frequencies of genotype1/2 and IL-1RN allele 2 in patients with chronic hepatitis B were lower than those in controls (P=0.016 and P=0.029, respectively). CONCLUSION: There is an association between polyrnorphisms of the promoter region -511C/T of IL-1B and IL-1RN intron 2 and chronic hepatitis B virus infection. SubJects with IL-1RN 2 may be resistant to HBV infection, and IL-1B(-511) geNotype CC is closely related with HBV-DNA replication, which gives some new clues to the study of pathogenesis of chronic hepatitis B.

Association of polymorphisms of interleukin-18 gene promoter region with chronic hepatitis B in Chinese Han population

AIM: To investigate the polymorphisms of interleukin-18 (IL-18) gene promoters, and to disclose whether such polymorphisms are associated with susceptibility to chronic hepatitis B in Chinese Han population. METHODS: Using polymerase chain reaction with sequence specific primers (PCR-SSP) method, the single nucleotide polymorphisms (SNPs) of the promoter region of IL-18 gene at position -607 and -137 were detected in 231 patients with chronic hepatitis B and 300 normal controls. RESULTS: Allele C at position -607 in the promoter of IL-18 gene was detected in 48.7% of normal controls and 51.9% of patients, while allele A at position -607 was detected in 51.3% of normal controls and 48.1% of patients. The frequencies of -607CC, -607 CA and -607AA genotypes in normal controls were 22.0%, 53.3% and 24.7% respectively and in chronic hepatitis B patients were 26.8%, 50.2% and 23.0% respectively. Allele G at position -137 in the promoter of IL-18 gene was detected in 82.3% of normal controls and 88.5% of chronic hepatitis B patients, while allele C at position -137 was detected in 17.7% of normal controls and 11.5% of patients. The frequencies of -137GG, GC and CC genotype were 67.3%, 30.0% and 2.7% in normal controls respectively, while in chronic hepatitis B patients were 78.8%, 19.5% and 1.7% respectively. The frequency of-137GG genotype in chronic hepatitis B groups was significantly higher than that in normal controls (x2=8.55, P=0.003 <0.05), whereas the frequencies of -607C/-137C and -607A/-137C haplotypes in chronic hepatitis B groups were significantly lower than that in normal controls. The association between genotypes of IL-18 promoter region polymorphisms and HBV copies showed that the frequency of -607AA genotype in high HBV-DNA copies groups was lower than that in low HBV-DNA copies groups (x2=6.03, P=0.014 <0.05). CONCLUSION: The polymorphisms of the promoter region of IL-18 gene at position -607 and -137 are closely associated with susceptibility to chronic hepatitis B. The people with allele C at position -137 in the promoter of IL-18 gene may be protected against HBV infection; moreover AA genotype at position -607 may be closely linked to inhibit HBV-DNA replication. These findings give some new clues to the study of pathogenesis of chronic hepatitis B.

Antiproliferative effect of octreotide on gastric cancer cells mediated by inhibition of Akt/PKB and telomerase

AIM: To investigate the antiproliferative effect of octreotide,a long-acting analogue of somatostatin, on gastric cancer cell line SGC7901 and its possible molecular mechanisms.METHODS: Gastric cancer cell line SGC7901 employed in the study was treated with 0.008, 0.04, 0.2, 1, 5 and 25μg@ml-1 of octreotide respectively for 24 h to evaluate the antiproliferative effect of somatostatin analog on the tumor cells by MTT assay method. To elucidate the underlying mechanism, the cells were exposed to 1 μg@ml-1 of octreotide for 0, 12, 24 and 48 h, when their Akt/PKB and telomerase activities were respectively determined using PCR-ELSIA and nonradioactive protein kinase assay protocols. The same experimental procedures were also performed in the control cells that were treated with corresponding vehicles instead of somatostatin analog.RESULTS: After exposed to octreotide for 24 h at the concentrations of more than 1 μg@ml-1 SGC7901 cells exhibited a dose-dependent inhibition of growth with the inhibiting rate to be as high as 34.66 % when 25 μg@ml-1 of octreotide was applied. The Akt/PKB and telomerase activity of SGC7901 cells was significantly inhibited when the cells were exposed to 1 μg@ml-1 of octreotide for 12, 24 and 48 h compared with that of their control counterparts (P＜0.01),both of which exhibited in a time-dependent manner.CONCLUSION: The antiproliferative effect of octreotide on SGC7901 cells might be mediated by the inhibition of Akt/PKB and telomerase.

Single nucleotide polymorphism in DNA methyltransferase 3B promoter and its association with gastric cardiac adenocarcinoma in North China

AIM:To investigate the association between single nucleotide polymorphism (SNP) in promoter of the DNA methyltrans-ferase 3B(DNMT3B) gene and risk for development and lymphatic metastasis of gastric cardiac adenocarcinoma (GCA). METHODS: The hospital based case-control study included 212 GCA patients and 294 control subjects without overt cancer. The DNMT3B SNP was genotyped by PCR and restriction fragment length polymorphism (RFLP) analysis. RESULTS: The C/C genotype was not detected in both GCA patients and controls. In control subjects, the frequency of T/T and C/T genotypes was 94.9% and 5.1% respectively, and that of T and C alleles was 97.4% and 2.6%, respectively. The genotype and allelotype distribution in the GCA patients was not significantly different from that in controls (P=0.34 and 0.33, respectively). When stratified by smoking status and family history of upper gastrointestinal cancer, significant difference in the genotype distribution was not observed between GCA patients and controls. The distribution of DNMT3B genotypes in GCA patents with or without lymphatic metastasis did not show significant difference (P= 0.42). CONCLUSION: The distribution of DNMT3B SNP in North China is distinct from that in Caucasians. Although this SNP has been associated with susceptibility to lung, head, neck and breast cancer, it may not be used as a stratification marker to predict susceptibility and lymphatic metastasis of GCA, at least in the population of North China.

No association of the matrix metalloproteinase 1 promoter polymorphism with susceptibility to esophageal squamous cell carcinoma and gastric cardiac adenocarcinoma in northern China

AIM: To investigate association of the 2Gor1Gsingle nudeotide polymorphism (SNP) in matrix metalloproteinase 1 (MMP1) promoter with susceptibility to esophageal squam-ous cell carcinoma (ESCC) and gastric cardiac adenocarcinoma (GCA) in a population of North China. METHODS: MMP1 promoter SNP was genotyped by polymerase-chain reaction (PCR)-restriction fragment length polymorphism (RFLP) analysis in 417 cancer patients (234 ESCC and 183 GCA) and 350 healthy controls. RESULTS: The genotype frequencies of the MMP1 promoter SNP in healthy controls were 55.4% (2G/2G), 30% (1G/2G) and 14.6% (1G/1G), respectively. The genotype and allelotype distribution in ESCC and GCA patients was not significantly different from that in healthy controls (all lvalues were above 0.05). Compared with the 1G/1Ggenotype, neither the 2G/2Gnor in combination with the 1G/2G genotype significantly modified the risk of developing ESCC and GCA, the adjusted odds ratio was 1.28 (95%CI = 0.78-2.09), 1.23 (95%CI = 0.38-2.05) in ESCC and 1.39 (95%CI = 0.80-2.41), 1.34 (95%CI = 0.74-2.40) in GCA, respectively. When stratified by smoking status and family history of upper gastrointestinal cancer, the 2G/2Ggenotype alone or in combination with the 1G/2G genotype also did not show any significant influence on the risk of ESCC and GCA development. In addition, influence of the MMP1 SNP on lymphatic metastasis in ESCC and GCA was also not obs-erved. CONCLUSION: The 2Gor 1GSNP in the MMP1 promoter might not modify the risk of ESCC and GCA development and might not be used as a stratification marker to predict the potential of lymphatic metastasis in these two tumor types.

Visualization of Golgia apparatus as an intracellular calcium store by laser scanning confocal microscope

Using laser scanning confocal microscopy, we have found that the in cells loaded with fluo-3/AM, highest intracellular Ca(2+) in the perinuclear region is associated with the Golgi apparatus. The spatiotemporal subcellu lar distribution of Ca(2+) in living human fibroblasts exposing to calcium-free medium in response to agonists has been investigated. PDGF, which releases Ca(2+) from intracellular stores by inositol(1, 4, 5)-trisphosphate pathway,produced a biphasic transient rise in intracellular calcium.The initial rise was resulted from a direct release of calcium from the Golgi apparatus. Calcium could be also released from and reaccumulated into the Golgi apparatus by the stimulation of thapsigargin, an inhibitor of the Ca(2+) transport ATPase of intracellular calcium store. Permeablizing the plasma membrane by 10 μM digitonin resulted in the calcium release from the Golgi apparatus and depletion of the internal calcium store. These results suggest that the Golgi apparatus plays a role in Ca(2+) regulation in signal transduction.

Epoxide hydrolase Tyr113 His polymorphism is not associated with susceptibility to esophageal squamous cell carcinoma in population of North China

AIM: To investigate the possible association of microsomal epoxide hydrolase ( mEH) Tyr113 His polymorphism with susceptibility to esophageal squamous cell carcinoma (ESCC) in a population of North China.METHODS: The mEH-Tyr113 His genotypes were determined by polymerase-chain reaction (PCR)-restriction fragment length polymorphism (RFLP) analysis in 257 patients with esophageal squamous cell carcinoma (ESCC) and 252 healthy subjects as a control group.RESULTS: The frequencies for Tyr and His alleles were 44.2 %, 55.8 % in ESCC patients, and 44.0 % and 56.0 %in healthy subjects, respectively. No statistic difference in allele distribution was observed between ESCC patients and controls (x2=0.008, P=0.929). The overall genotype distribution difference was not observed between cancer cases and controls (x2=2.116, P=-0.347). Compared with Tyr/Tyr genotype, neither His/His genotype nor in combination with Tyr/His genotype significantly modified the risk of the development of ESCC, the adjusted odds ratio was 1.076 (95 % CI=0.850-1.361) and 0.756 (95 % CI=0.493-1.157),respectively. When stratified for sex, age, smoking status and family history of upper gastrointestinal cancer, His/His genotype alone or in combination with Tyr/His genotype also did not show any significant influence on the risk of developing ESCC.CONCLUSION: MEH Tyr113His polymorphism may not be used as a stratification marker in screening individuals at a high risk of ESCC.

Separation of the Martensite in TiNi Fiber Reinforced Aluminum Matrix Composite

The reverse martensitic transformation of TiNi shape memory alloy fibers embedded in a pure aluminum matrix was studied in this paper. Results showed that the phase composition of the TiNi alloy fibers prior to prestraining at the room temperature had a significant influence on the differential scanning calorimetry (DSC) results of the composites. By a comparison to the high temperature X-ray diffraction (XRD) results, it was confirmed that the martensite was divided into two groups: the self-accommodating martensite (SAM) and the preferentially oriented martensite (POM). The evolving process of the separation of martensite was discussed.

The thymic stromal cell line MTSC4 induced thymocyte apoptosis in a non-MHC-restricted manner

Mouse thymic stromal cell line 4 (MTSC4) is one of the stromal cell lines established in our laboratory. While losing the characteristics of epithelial cells, they express some surface markers shared with thymic dendritic cells (TDCs). To further study the biological functions of these cells, we compared the capability of MTSC4 with TDCs in the induction of thymocyte apoptosis, using thymic reaggregation culture system. Apoptosis of thymocytes induced by MTSC4 and TDCs was measured by Annexin V and PI staining and analyzed by flow cytometry. We found that MTSC4 selectively augmented the apoptosis of CD4^+8^+ (DP) thymocytes. This effect was Fas/FasL independent and could not be blocked by antibodies to MHC class Ⅰ and class Ⅱ molecules. In addition, MTSC4 enhanced the apoptosis of DP thymocytes from different strains of mice, which implies that MTSC4-induced thymocyte apoptosis is not mediated by the TCR recognition of self peptide/MHC molecules. In contrast to MTSC4, thymocyte apoptosis induced by TDCs was MHC-restricted. Thus, MHC-independent fashion of stromal-DP thymocyte interaction may be one of the ways to induce thymocyte apoptosis in thymus. Our study has also shown that the interaction of MTSC4 stromal cells and thymocytes is required for the induction of thymocyte apoptosis.

Visualization and Damage Assessment for Flooded Area

A practical method for visualizing flood area and evaluating damage is presented, which consists of two technical approaches: self\|programming and adapting commercial GIS platforms. The low\|cost and easy\|to\|use GIS\|Based model developed by self\|programming can meet current requirements of most local authorities, especially in developing countries. In this model, two cases, non\|source flood and source flood, are distinguished and the Seed\|spread algorithm suitable for source\|flood is discussed; The flood damage is assessed by overlaying the flood area range with thematic maps and other related social and economic data. and all thematic maps are converted to raster format before overlay analysis. Two measures are taken to improve the operation efficiency of speed seed\|spread algorithm. The accuracy of the model mainly depends on the resolution and precision of the DEM data, and the accuracy of registering all raster layers and the quality of attribute data.

POSTOPERATIVE EVALUATION OF TENSION-FREE VAGINAL TAPE PROCEDURE

Objective To study the outcome of tension-free vaginal tape (TVT) for the treatment of stress urinary incontinence (SUI) in women with cystocele. Methods Forty-two patients with SUI confirmed by urodynamics underwent the TVT procedure under local anesthesia. A prolapse repair was done simultaneously. Results Mean TVT operation time was 26.29 minutes. Mean blood loss was 29.86 mL. Eighty-eight percent of the patients were able to micturate spontaneously within 12 hours and residual urine was less than 100 mL. And 12% of the patients had to use indwelling catheter for 3-11 days. Average hospital stay was 2.91 days. Eighty-eight percent of patients were discharged within 2 days. All patients were followed up (an average of 10.26 months). According to subjective and objective assessment of the outcome, 39 patients (93%) were cured, another 3 patients (7%) were significantly improved and none was failed. There were no major complications such as bladder injury occurred. Conclusion TVT procedure is a minimal invasive, effective, and safe surgery for treatment of SUI.

A Model of the Circumstellar Envelope of Luminous Blue Variables

The continuum energy distributions of the luminous blue variables R127 and R110 in the outburst phase are fitted with a circumstellar envelope model. Both stars show two peaks in their continuum, one near 1250? and the other in the optical band. We suggest that their UV and optical fluxes may have different origins: the UV flux comes from the central star while the optical flux comes from an expanding circumstellar envelope. We construct a model for LBVs consisting of two LTE atmosphere models with different temperatures, and find it to be in agreement with the observed spectral energy distributions of R127 and R110. According to our numerical experiments, R127's continuum is composed of fluxes from a circumstellar envelope of Teff = 8000 K, R = 485R⊙, and log g = 1, and from a central star of Teff = 17?000 K, R = 135R⊙, and log g = 2.5 with a permeating factor f = 0.5; while R110's continuum can be fitted by a circumstellar envelope of Teff = 7000 K, R = 350R⊙, and log g = 0.5, and a central star of Teff = 25?000 K, R = 27R⊙, and log g = 3.0 with a permeating factor f = 0.65. Both models show that the non-spherically symmetric, optically thick regions are formed surrounding the central star in the outburst phase. The light of the central star is shielded by the circumstellar envelope so that the visual brightness increases with the decrease/increase of the temperature/radius of the optically thick regions.

mRNA Expression of Vimentin Gene in Lens of Transgenic Mouse and DNA Amplification in Human Cataracts

Purpose:To investigate the role of vimentin gene in cataractogenesis.Methods:The12.7kb chicken vimentin genes were microinjected into the male pronuclei of 918 fertilized mice eggs.841injected embryos were transferred into oviducts of pseudopregnant recipient females.of which 12pregnant mice gave birth to 49offsping mice.The integration and expression of exogenous gene in the offsping were analysed by Southern and Northern blot byhridizations,In the human senile cataract,the lens vimentin gene was analyzed with the chicken vi-mentin gene probe.Results:It showed that four of F1offspring were transgenic mice in which the chicken vimenttin gene was integrated in their genomes.The transgenic band was12kb,similar to the12.7kb chicken vimentin fragment injected.One2kbvi-mentin mRNAwas visualized on E2 mouse lens blot.which revealed that the chicken vimentin gene was efficiently expressed in this transgenic mouse.In the humansenile cataract lens,12kb BamHI-restricted vimentin fragments displayed a stronger hybridization signal than that of the control lens in Southern blot anal-ysis,It implies that the Formation of human senile cataract may be associated with the amplification of vimentin gene.Conclusions:We have successfully developed four transgenic mice bearing chicken vimentin gene and having mRNA expression which can be used for further study.It is to be observed if the normal lens cell function is affected by the expressed product and cataract occurs in our transgenic mice.The cause of the gene ampli-fication in human ctaract remains for further investigation.Eye Science 1995;11:113-116.

Anisotropy and Dissipation of Turbulence and Their Effects on Solar Models

Based on a dynamic model for turbulent convection, we investigate the effects of dissipation and anisotropy of the turbulence on the convective energy transport. We introduce two time scales to describe the dissipation of the turbulence, and approximate the anisotropy of the turbulence by Rotta's proposal of 'return to isotropy'. The improved turbulence model results in an equation to determine the temperature gradient in the convection zone, which is of similar form as that of the MLT. We apply the improved MLT to solar models, and find that the increases of the anisotropy and decreases of the dissipation of the turbulence reduce the value of the convection parameter a, because these processes enhance the convective energy transfer rate. Compared with the observed solar p-mode frequencies, it is plausible that the dissipation of the turbulence in the solar convection zone should be fairly strong, while the degree of anisotropy of the turbulence plays a less significant role on the structure of the solar convection zone.

THE PAIRS OF COOKS IN THE ROYAL DINING HALL AND THE AKITI CALENDAR DURING ?ULGI 45 – 48

Wu Yuhong published an article on the animals issued to the 6-uz-ga institution and its two cooks, in addition to two articles on the Calendar starting from the Month of Akiti in Puzris-Dagan, in 1996, 2000 and 2002. From 2006, more and more Puzris-Dagan texts have been available to us through BDTNS and CDLI online, and this situation urged us to revise and make a complete archive of the four pairs of cooks （muhaldim） working in the e-uz-ga dining hall,

基于氮,膦配体多孔有机聚合物材料的设计合成及其催化应用

多孔有机聚合物(porous organic polymers,POPs)是近年来涌现出的由纯粹的有机分子砌块,通过共价键连接而成的一类具有高比表面积、丰富的孔结构、低骨架密度和良好热稳定性的新型材料。而N,P配体在均相过渡金属络合物催化的氢甲酰化反应、偶联反应、加氢反应、硅氢加成反应,CO2环加成等反应中具有重要的应用,通过合理的设计和修饰N,P配体的电子效应和立体结构,可有效地调控目标产物的收率和选择性。得益于有机合成策略的多样性,POPs材料也具有合成路径及构建方式多样,可较为方便地在聚合物骨架中定点引入特定功能位点的特点,这为基于N,P配体均相过渡金属催化剂的多相化提供了全新的思路与契机。本文将对国内国外相关课题组及本课题组在基于N,P配体POPs材料的设计合成及其催化应用方面所做的工作进行简要的总结归纳,并对该方向进行相应的工业应用前景展望。

A Genome Sequence of Novel SARS-CoV Isolates: the Genotype, GD-Ins29, Leads to a Hypothesis of Viral Transmission in South China

We report a complete genomic sequence of rare isolates (minor genotype) of the SARS-CoV from SARS patients in Guangdong, China, where the first few cases emerged. The most striking discovery from the isolate is an extra 29-nucleotide sequence located at the nucleotide positions between 27,863 and 27,864 (referred to the complete sequence of BJ01) within an overlapped region composed of BGI-PUP5 (BGI-postulated uncharacterized protein 5) and BGI-PUP6 upstream of the N (nucleocapsid) protein. The discovery of this minor genotype, GD-Ins29, suggests a significant genetic event and differentiates it from the previously reported genotype, the dominant form among all sequenced SARS-CoV isolates. A 17-nt segment of this extra sequence is identical to a segment of the same size in two human mRNA sequences that may interfere with viral genome replication and transcription in the cytosol of the infected cells. It provides a new avenue for the exploration of the virus-host interaction in viral evolution, host pathogenesis, and vaccine development.