生物电化学仪器的发展现状与展望

电荷传递是生命运动的基本过程之一,电化学方法在生命科学中的应用为相关生命现象的研究提供了一个有效而独特的物理化学视角,并带来超出常规生物学检测的丰富信息.随着生物电化学研究的不断扩展和深化,已从早期的生物分子电化学研究深入向活体、活细胞、单活细胞水平甚至活细胞中单分子水平发展.研究者对仪器设备性能如灵敏度、分辨率(时间分辨、空间分辨和能量分辨)和操作性等提出了越来越高的要求.本文综述了生物电化学仪器在应用领域和研究领域的现状,重点介绍单细胞电化学检测系统的构建,并初步探讨国内生物电化学研究仪器的发展趋势.

Modulation of Lianbizi Injection (Andrographolide ) on Some Immune Functions

Objective: To study the effects of andrographolide on immune functions and the immune mechanism in clinical therapy.Methods: The amounts of IFN-α,IFN-γ, TNF-α, IL-8 in the peripheral blood mononuclear cells (PBMC) culture supernatants dealt with by different concentrations of LianBiZhi (LBZ) injection, the effective component of which is andrographolide, were detected by biological activity test or ELISA in vitro. The effects of LBZ injection on macrophage phagocytotic function and natural killer cells cytotoxicity were examined by means of macrophage to phagocytize cock erythrocyte and measurement of lactate dehydrogenase (LDH) activity released from the damaged cells, respectively.Results: The LBZ injection could not only enhance the phagocytosis activity of peritoneal macrophage from guinea pig to phagocytosis cock erythrocytes, but also augment the cytotoxicity mediated by natural killer cells from PBMCs.Conclusion: Andrographolide is an immunostimulant agent which can modulate both antigen specific and nonspecific immune function by means of its natural killer cells, macrophage and cytokines.

Lactobacilli,bifi dobacteria and E.coli nissle induce pro-and anti-inflammatory cytokines in peripheral blood mononuclear cells

AIM： To investigate whether the stimulation of peripheral blood mononuclear cells （PBMNC） with the cell debris and cell extraction of different probiotic strains is similar or species specific. METHODS： Three strains of bifidobacteria, 4 strains of lactobacilli, and E. coli nissle were sonicated and centrifuged in order to divide them into cell extract and cell debris. PBMNC were separated by density gradient and incubated for 36 h with either the cell debris or the cell extract of single strains of probiotic bacteria in doses from 10^2 to 10^8 CFU/mL. Cell supernatants were taken and interleukin （IL）-10, IL-1β, and tumor necosis factor （TNF）-α were determined by ELISA. RESULTS： Depending on the species super-family, the strains had different stimulation patterns. Except for both L. casei strains, the cell extract of bitTdobacteria and/actobacilli had less stimulating capacity than cell debris, whereas the cell extract of E. coli nissle had similar stimulating properties to that of the cell debris of the strain and significantly more stimulating capacity than that of bifidobacteria and lactobacilli. The cell debris of bifidobacteria stimulated more cytokine release than the cell debris of lactobacilli. The cell debris of lactobacilli did not have a stimulating capacity when lower concentrations were used. Neither cell extraction nor cell debris had an inhibitory effect on the production of the tested cytokines by stimulated PBMNC. CONCLUSION： The incubation of probiotic strains, which have been used in clinical trials for inflammatory diseases, with immunocompetent cells leads to different species specific reactions. High IL-10 response to cell debris of bifidobacteria and E. coli nissle can be found. This corresponds to positive effects of bihdobacteria and E. coli nissle in clinical trials for inflammatory bowel disease compared to negative outcomes obtained with lactobacilli.

Cytomegalovirus hepatitis and myopericarditis

Cytomegalovirus (CMV) infection in inmunocompetent hosts generally is asymptomatic or may present as a mononucleosis syndrome but rarely can lead to severe organ complications. We report a case of simultaneous hepatic and pericardic CMV infection in a 36-year old immunocompetent man. He was admitted to coronary unit with fever, chest pain radiated to shoulders, changes on electrocardiogram with diffuse ST elevation and modest laboratory elevations in the MB fraction of creatine kinase (CK-MB) of 33.77 μg/L (0.1-6.73), serum cardiac troponin T of 0.904 ng/mL (0-0.4), creatine kinase of 454 U/L (20-195) and myoglobin of 480.4 μg/L (28-72). Routine laboratory test detected an elevation of aminotransferase level: alanine aminotransferase 1445 U/L, aspartate aminotransferase 601 U/L. We ruled out other causes of hepatitis with normal results except IgM CMV. The patient was diagnosed with myopericarditis and hepatitis caused by cytomegalovirus and started symptomatic treatment with salicylic acid. In few days the laboratory findings became normal and the patient was discharged.

ANTITUMOR ACTIVITY OF IMMUNOCONJUGATES COMPOSED OF BOANMYCIN AND MONOCLONAL ANTIBODY

Boanmycin (bleomycin A6 . BM) . an antitumor antibiotic, was conjugated to monoclonal antibodies including R19, H 111 and CCT2. The immunoconjugates exhibited selective cytotoxicity to related target cells including cecum cancer Hce-8693 cells, liver cancer BEL-7402 cells and leukemia CEM cells. They were highly effective against related human tumor xenografts in nude mice, and the inhibition rates by the conjugates were much higher than those by free BM. The inhibition rate by R19-BM conjugate against human cecum cancer xenografts reached 90%. BY immunoelectron microscopy, CCT2-BM conjugate showed specific binding and internalization in leukemia CEM cells. The results indicate that boanmycin-monoclonal antibody immunoconjugates are highly active both in vitro and in vivo.

Cilostazol inhibits plasmacytoid dendritic cell activation and antigen presentation

Background Cilostazol, an anti-platelet drug for treating coronary heart disease, has been reported to modulate immune cell functions Plasmacytoid dendritic cells （pDCs） have been found to participate in the progression of atherosclerosis mainly through interferon ct （IFN-ct） production. Whether cilostazol influences pDCs activation is still not clear. In this study, we aimed to investigate the effects of cilostazol on cell activation and antigen presentation ofpDCs in vitro in this study. Methods Peripheral blood mononuclear cells isolated by Ficoll cen- trifugation and pDCs sorted by flow cytometry were used in this study. After pretreated with cilostazol for 2 h, cells were stimulated with CpG-A, R848 or virus for 6 h or 20 h, or stimulated with CpG-B for 48 h and then co-cultured with naive T cell for five days. Cytokines in supernatant and intracellular cytokines were analyzed by ELISA or flow cytometry respectively. Results Our data indicated that cilostazol could inhibit IFN-α and tumor necrosis factor α （TNF-α） production from pDCs in a dose-dependent manner. In addition, the ability of priming na ve T cells of pDCs was also impaired by cilostazol. The inhibitory effect was not due to cell killing since the viability of pDCs did not change upon cilostazol treatment. Conclusion Cilostazol inhibits pDCs cell activation and antigen presentation in vitro, which may explain how cilostazol protects against atherosclerosis.

Antagonistic Activity, Antimicrobial Susceptibility and Potential Virulence Factors of Enterococcus faecalis

Enterococcus faecalis isolates （87） were phenotypically and genotypically identified and subsequently subjected to the antagonism test and antimicrobial susceptibility. The lipolitic, hemolytic and DNAse activities were identified along with the genes gelE, cylL, cylS, ccf, cpd and cob that, encode virulence determinants. Thirty seven percent of isolates inhibited Listeria monocytogenes （CERELA）, Listeria innocuous （CERELA）, Staphylococcus aureus （ATCC25932）, Lactococcus lactis （IL1403）, Micrococcus luteus （ATCC 10240） and Enterococcusfaecalis （ATCC29212）. All strains were sensitive to the ampicillin antibiotic, but 47% were resistant to at least one antimicrobial agent and 6% of isolates presented multidrug resistance. Ninety seven percent of isolates contained the gelE gene, but 77% of these isolates showed gelatinase activity. Presence of cylL and cylS genes was observed in 25% of the isolates, but only 5% presented hemolytic activity. None isolates showed lipase and DNAse activities. Eight percent of isolates contained the ccf gene and 2% showed the presence of the cpd and cob genes. The ability to inhibit pathogenic bacteria, low resistance to antibiotics and absence of virulence factors make some of Enterococcusfaecalis strains characterized in the present study promising for exploitation in other applications such as probiotics in aquaculture.

Inhibitory activity of an extract from a marine bacterium Halomonas sp.HSB07 against the red-tide microalga Gymnodinium sp.(Pyrrophyta)

In recent years,red tides occurred frequently in coastal areas worldwide.Various methods based on the use of clay,copper sulfate,and bacteria have been successful in controlling red tides to some extent.As a new defensive agent,marine microorganisms are important sources of compounds with potent inhibitory bioactivities against red-tide microalgae,such as Gymnodinium sp.(Pyrrophyta).In this study,we isolated a marine bacterium,HSB07,from seawater collected from Hongsha Bay,Sanya,South China Sea.Based on its 16S rRNA gene sequence and biochemical characteristics,the isolated strain HSB07 was identified as a member of the genus Halomonas.A crude ethyl acetate extract of strain HSB07 showed moderate inhibition activity against Gymnodinium sp.in a bioactive prescreening experiment.The extract was further separated into fractions A,B,and C by silica gel column chromatography.Fractions B and C showed strong inhibition activities against Gymnodinium.This is the first report of inhibitory activity of secondary metabolites of a Halomonas bacterium against a red-tide-causing microalga.

Investigation of Argentinean Plant Extracts for Their Antibacterial Activity

Plants of Baccharis （Asteraceae） genus are commonly known in Argentina as ＂carqueja＂. The antimicrobial activity and minimal inhibitory concentration of B. articulata, B. trimera and B. crispa aqueous and ethanolic extracts were evaluated by using the micro-well dilution method. Previously, the components of extracts were analyzed by spectroscopial means. Gram-positive bacteria were more sensitive to Baccharis species extracts than Gram-negative bacteria. Out of 3 plant species, B. trimera showed significant antibacterial activity and aqueous and ethanolic extracts were active against Staphylococcus aureus （MIC = 2,500 μg/mL and 1,250 μg/mL, respectively） and Listeria monocytogenes （MIC = 625 μg/mL and 625 μg/mL, respectively）. All ethanolic extracts inhibited the growth of the selected Gram-positive （MIC values ranged between 625 μg/mL and 1,250 μg/mL）. Therefore, all Gram-negative bacteria were resistant to the ethanolic and aqueous extracts tested. One flavone, genkawanin, was identified from the three ethanolic extracts as the responsible of antibacterial activity. Two terpenes, hawtriwaic acid and bacrispine, were identified from ethanolic extract of B. crispa and B. trimera as the responsibles of antibacterial activity. These preliminary studies corroborated the antimicrobial activity of the selected plants used in folklore medicine. Therefore, they could be potential sources of new antimicrobial agents used in treatment of infectious diseases.

TLR4 -2242 T→C variant increases transcriptional activity of its promoter

Objective:To investigate the effects of -2242,-1892 and -1837 single nucleotide polymorphisms(SNPs) on toll-like receptor 4(TLR4) promoter activity.Methods:Polymerase chain reaction(PCR) and site direct mutation technology were used to construct TLR4 basic promoter and -2242C,-1892A and -1837G mutate promoter plasmids.Dual-Luciferase Reporter assay system was used to detect the activity of constructed promoter following human embryonic kidney(HEK) 293 cells were transiently cotransfected with the constructed plasmids and the control plasmid pRL-CMV.Results:In HEK293 cells,the activity of -2242C mutate promoter was higher than -2242T promoter,and there was no significant difference when both -1892A and -1837G mutate promoter compared with -1892G and -1837A promoter,respectively.Conclusion:It is implied that -2242T→C base variation can enhance the activity of TLR4 promoter,while -1892 and -1837 SNPs have no effect on TLR4 promoter activity.

The relations between density of FACs in the Plasma Sheet Boundary Layers and Kp index

We have studied 172 field-aligned currents （FACs） cases observed by the ClusterlI satellites when they crossed the plasma sheet boundary layer （PSBL） in the magnetotail from July to October 2001. We mainly analyzed the relationship between the characteristic of FACs at the PSBL in magnetotail and the Kp index. The main results indicated the followings： 1） In the different geomagnetic activity levels, the relative occurrence of FACs in PSBL increased monotonically with geomagnetic activity. 2） The density of FACs in PSBL increased monotonically with Kp index. In the storm main phase, the density of FACs increased dramatically, the maximum FACs approximately equaled 19.05 nA m-2 while Kp equaled 5.3） The variation of FACs density in PSBL was consistent with the variation of the Kp index. However, when AE〈800 nT, FACs density in PSBL increased with increasing AE, and when AE〉800 nT, it decreased with increasing AE. Therefore, our results suggested that the FACs density in PSBL had a closer correlation with Kp index.

Super-resolution imaging and tracking of TGF-β receptor II on living cells

Single-particle tracking photoactivated local- ization microscopy （sptPALM） has recently emerged as a powerful tool for high-density imaging and tracking of individual molecules in living cells. In this work, we have monitored and compared the diffusion dynamics of TGF-β type II receptor （TβRII） at high expression level using both traditional single-particle tracking （SPT） and sptPALM. The ligand-induced aggregation of TβRII oligomers was further indicated by sptPALM. Due to the capacity of distinguishing and tracking single molecules within diffraction limit, sptPALM outperforms traditional SPT by providing more accurate biophysical information,