Effects of titanium dioxide nanoparticles and lipopolysaccharide on antioxidant function of liver tissues in mice / 北京大学学报(医学版)

OBJECTIVE@#To compare the effects of different sized titanium dioxide (titanium dioxide, TiO2) on the antioxidant function of liver tissues in mice, and study the effect of TiO2 nanoparticles on the susceptibility of lipopolysaccharide (LPS) on liver tissues.@*METHODS@#Ninety 4-week-old clean-grade male ICR mice were divided into 18 groups, in which the mice were fed for different feed involving ordinary feed, nanometer TiO2 feed which meant the feed including 1% (mass fraction) TiO2 nanoparticles, and submicron TiO2 feed which meant the feed including 1% (mass fraction) TiO2 submicron particles. Respectively, they were fed for 1 month, 3 months and 6 months. On the second day after the feeding, respectively, 0 and 10 mg/kg LPS were given by gavage. The mice were harvested after 4 h and the body weight and liver weight for calculating the liver coefficient were recorded. Then the liver tissue homogenates were prepared for determining the antioxidant indexes including the total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-PX), and malondialdehyde (MDA).@*RESULTS@#The change of body weight in mice was only discovered in group fed for 1 month, which showed significant decrease of body weight in treatment groups compared with control group. And there was no significant change of the liver coefficient in each group. Compared with control groups, nanometer TiO2 groups and submicron TiO2 group, the activity of T-AOC, T-SOD and MDA of nanometer TiO2+LPS group and submicron TiO2+LPS group in which the mice were fed for 1 month and 6 months increased in different degree. And another result was also existing. The MDA activity of liver in different sized treatment groups fed for 3 months decreased. Neither significant difference between the results of different sized TiO2 treatment groups, nor significant difference among different sized TiO2 groups and the control groups were observed.@*CONCLUSION@#Longterm peroral TiO2 nanoparticles and TiO2 submicron particles are more likely to cause damage to the liver in the growing mice, and the damage may be either reductive or oxidative. In addition, small sized TiO2 can increase the susceptibility of mice liver to LPS and the susceptibility will increase with the increase of exposure time.

Research progress of synaptic vesicle recycling / 生理学报

Neurotransmission begins with neurotransmitter being released from synaptic vesicles. To achieve this function, synaptic vesicles endure the dynamic "release-recycle" process to maintain the function and structure of presynaptic terminal. Synaptic transmission starts with a single action potential that depolarizes axonal bouton, followed by an increase in the cytosolic calcium concentration that triggers the synaptic vesicle membrane fusion with presynaptic membrane to release neurotransmitter; then the vesicle membrane can be endocytosed for reusing afterwards. This process requires delicate regulation, intermediate steps and dynamic balances. Accumulating evidence showed that the release ability and mobility of synapses varies under different stimulations. Synaptic vesicle heterogeneity has been studied at molecular and cellular levels, hopefully leading to the identification of the relationships between structure and function and understanding how vesicle regulation affects synaptic transmission and plasticity. People are beginning to realize that different types of synapses show diverse presynaptic activities. The steady advances of technology studying synaptic vesicle recycling promote people's understanding of this field. In this review, we discuss the following three aspects of the research progresses on synaptic vesicle recycling: 1) presynaptic vesicle pools and recycling; 2) research progresses on the differences of glutamatergic and GABAergic presynaptic vesicle recycling mechanism and 3) comparison of the technologies used in studying presyanptic vesicle recycling and the latest progress in the technology development in this field.

Experimental studies on treatment of HSV infections with photodynamic therapy using 5-aminolevulinic acid / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To investigate in vitro and in vivo anti-human herpes simplex virus effects of photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA).</p><p><b>METHODS</b>Guinea pigs model of cutaneous herpes virus infection was applied, and Vero cells infected by HSV-I and HSV-II were used as experimental systems to observe the antiherpes effect of ALA-PDT.</p><p><b>RESULTS</b>The in vitro experiments showed that ALA-PDT has antiherpes effect on HSV-I and HSV-II, its effect was similar to that of acyclovir. The results of animal experiments showed that ALA-PDT had significant therapeutic effect on guinea pigs model of cutaneous herpes virus infection, the effect was dose-related.</p><p><b>CONCLUSION</b>ALA-PDT could be effective in treating HSV infections, which may provide a new approach to the treatment of viral infections.</p>

Analysis of human H5N1 virus hemagglutinin gene isolated from the mainland of China / 中华实验和临床病毒学杂志

<p><b>BACKGROUND</b>To analyze the genetic and antigenic characteristics of human H5N1 virus isolated from the mainland of China.</p><p><b>METHODS</b>The hemagglutinin (HA) gene of human H5N1 virus were sequenced and analyzed.</p><p><b>RESULTS</b>The results of HA gene sequencing showed that all the virus isolates belong to the same group because of the high similarity, but they were different from the virus isolated from Thailand and Vietnam. The sequence data also showed that the receptor specificity and the connecting peptide between HA1 and HA2 are still avian influenza origin.</p><p><b>CONCLUSION</b>The virus isolates from mainland of China until now belong to the same group and are different from the virus isolated from Thailand and Vietnam, and there is no evidence showing the human-avian influenza reassortant and recombination.</p>

Efficient and quick inactivation of SARS coronavirus and other microbes exposed to the surfaces of some metal catalysts / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To study the two metal catalysts Ag/Al2O3 and Cu/Al2O3 that interdict the transmission pathway for SARS and other respiratory infectious diseases.</p><p><b>METHODS</b>Two metal catalysts Ag/Al2O3 and Cu/Al2O3 were pressed into wafers. One hundred microL 10(6) TCID50/mL SARS-CoV, 100 microL 10(6) PFU/mL recombinant baculovirus expressing hamster's prion protein (haPrP) protein and roughly 10(6) E. coli were slowly dropped onto the surfaces of the catalyst wafers and exposed for 5 and 20 min, respectively. After eluted from the surfaces of wafers, the infectivity of viruses and propagation of bacteria were measured. The expression of PrP protein was determined by Western blot. The morphological changes of bacteria were observed by electronic microscopy.</p><p><b>RESULTS</b>After exposure to the catalysts surfaces for 5 and 20 min, the infectivity of SARS-CoV in Vero cells and baculovirus in Sf9 cells dropped down to a very low and undetectable level, and no colony was detected using bacteria culture method. The expression of haPrP protein reduced to 21.8% in the preparation of Sf9 cells infected with recombinant baculovirus exposed for 5 min and was undetectable exposed for 20 min. Bacterial membranes seemed to be cracked and the cytoplasm seemed to be effluent from cell bodies.</p><p><b>CONCLUSION</b>Exposures to the surfaces of Ag/Al2O3 and Cu/Al2O3 destroy the replication and propagation abilities of SARS-CoV, baculovirus and E. coli. Inactivation ability of metal catalysts needs to interact with air, utilizing oxygen molecules in air. Efficiently killing viruses and bacteria on the surfaces of the two metal catalysts has a promising potential for air-disinfection in hospitals, communities, and households.</p>

SARS patients-derived human recombinant antibodies to S and M proteins efficiently neutralize SARS-coronavirus infectivity / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To develop a specific SARS virus-targeted antibody preparation for emergent prophylaxis and treatment of SARS virus infection.</p><p><b>METHODS</b>By using phage display technology, we constructed a naive antibody library from convalescent SARS patient lymphocytes. To obtain the neutralizing antibody to SARS virus surface proteins, the library panning procedure was performed on purified SARS virions and the specific Fab antibody clones were enriched by four rounds of repeated panning procedure and screened by highthroughput selection. The selected Fab antibodies expressed in the periplasma of E. coli were soluble and further purified and tested for their binding properties and antiviral function to SARS virus. The functional Fab antibodies were converted to full human IgG antibodies with recombinant baculovirus/insect cell systems and their neutralizing activities were further determined.</p><p><b>RESULTS</b>After four rounds of the panning, a number of SARS-CoV virus-targeted human recombinant Fab antibodies were isolated from the SARS patient antibody library. Most of these were identified to recognize both natural and recombinant SARS spike (S) proteins, two Fab antibodies were specific for the virus membrane (M) protein, only one bound to SARS-CoV nucleocapsid protein. The SARS-CoV S and M protein-targeted Fab or IgG antibodies showed significant neutralizing activities in cytopathic effect (CPE) inhibition neutralization test, these antibodies were able to completely neutralize the SARS virus and protect the Vero cells from CPE after virus infection. However, the N protein-targeted Fab or IgG antibodies failed to neutralize the virus. In addition, the SARS N protein-targeted human Fab antibody reacted with the denatured N proteins, whereas none of the S and M protein specific neutralizing antibodies did. These results suggested that the S and M protein-specific neutralizing antibodies could recognize conformational epitopes which might be involved in the binding of virions to cellular receptors and the fusion activity of the virus.</p><p><b>CONCLUSION</b>The SARS-CoV spike protein and membrane proteins are able to elicite efficient neutralizing antibodies in SARS patients. The neutralizing antibodies we generated in this study may be more promising candidates for prophylaxis and treatment of SARS infection.</p>

Anti-SARS virus activities of different recombinant human interferons in cell culture system / 中华实验和临床病毒学杂志

<p><b>BACKGROUND</b>To study the anti-SARS virus activities of different recombinant human interferons on the cell culture system.</p><p><b>METHODS</b>Anti-SARS virus activities of interferons were determined by using CPE inhibition test in human skeletal muscle sarcoma (Rda) cell culture.</p><p><b>RESULTS</b>The average minimum amount of interferon alpha 2b, alpha 1b, beta 1b or omega 1b to inhibit 50% CPE in Rda cell culture was (160.5+/-129.5) IU/ml, (149.0+/-71.7) IU/ml, (69.5+/-61.5) IU/ml, (87.3+/-47.1) IU/ml, respectively or (0.6+/-0.5) ng/ml, (10.6+/-5.1) ng/ml, (3.5+/-3.1) ng/ml, (0.9+/-0.5) ng/ml, respectively.</p><p><b>CONCLUSION</b>All the tested recombinant interferons showed anti-SARS virus activities on the Rda cell culture with different sensitivities.</p>