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排序方式: 共有9587条查询结果,搜索用时 93 毫秒
41.
A M Paredes D T Brown R Rothnagel W Chiu R J Schoepp R E Johnston B V Prasad 《Proceedings of the National Academy of Sciences of the United States of America》1993,90(19):9095-9099
The structure of Sindbis virus was determined by electron cryomicroscopy. The virion contains two icosahedral shells of viral-encoded proteins separated by a membrane bilayer of cellular origin. The three-dimensional structure of the ice-embedded intact Sindbis virus, reconstructed from electron images, unambiguously shows that proteins in both shells are arranged with the same icosahedral lattice of triangulation number T = 4. These studies also provide structural evidence of contact between the glycoprotein and the nucleocapsid protein across the membrane bilayer. The structural organization of Sindbis virus has profound implications for the morphogenesis of the alphaviruses. The observed interactions confirm stoichiometric and specific protein associations that may be crucial for virion stability and predict a mechanism for assembly. 相似文献
42.
The role of serotonin and glutamate release in dorsal medulla (DM) for regulation of systemic arterial pressure (SAP) was examined with microdialysis and high performance liquid chromatograph in anesthetized cats. KCl-perfusion in DM increased serotonin and glutamate concentrations in DM. Perfusion of serotonin resulted in decreases in glutamate concentration and SAP. Perfusion of alaproclate, a serotonin reuptake inhibitor that produced an increase in serotonin concentration in DM, had the same results as perfusion of serotonin. In conclusion, serotonin and glutamate appeared to be tonically and endogenously released from nerve terminals in DM, and the decrease in SAP could be attributed to the decreased glutamate release resulting from inhibitory action of serotonin in DM. The putative roles of serotonin and glutamate in DM may be important in SAP regulation. 相似文献
43.
Laboratory-based surveillance and molecular epidemiology of influenza virus in Taiwan 总被引:3,自引:0,他引:3
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Shih SR Chen GW Yang CC Yang WZ Liu DP Lin JH Chiu SC Chen HY Tsao KC Huang CG Huang YL Mok CK Chen CJ Lin TY Wang JR Kao CL Lin KH Chen LK Eng HL Liu YC Chen PY Lin JS Wang JH Lin CW Chan YJ Lu JJ Hsiung CA Chen PJ Su IJ 《Journal of clinical microbiology》2005,43(4):1651-1661
A laboratory-based surveillance network of 11 clinical virological laboratories for influenza viruses was established in Taiwan under the coordination of the Center for Disease Control and Prevention (CDC), Taiwan. From October 2000 to March 2004, 3,244 influenza viruses were isolated, including 1,969 influenza A and 1,275 influenza B viruses. The influenza infections usually occurred frequently in winter in the northern hemisphere. However, the influenza seasonality in Taiwan was not clear during the four seasons under investigation. For example, the influenza A viruses peaked during the winters of 2001, 2002, and 2003. However, some isolated peaks were also found in the summer and fall (June to November) of 2001 and 2002. An unusual peak of influenza B also occurred in the summer of 2002 (June to August). Phylogenetic analysis shows that influenza A isolates from the same year were often grouped together. However, influenza B isolates from the year 2002 clustered into different groups, and the data indicate that both B/Victoria/2/87-like and B/Yamagata/16/88-like lineages of influenza B viruses were cocirculating. Sequence comparison of epidemic strains versus vaccine strains shows that many vaccine-like Taiwanese strains were circulating at least 2 years before the vaccine strains were introduced. No clear seasonality of influenza reports in Taiwan occurred in contrast to other more continental regions. 相似文献
44.
Kam KM Luey CK Tsang YM Law CP Chu MY Cheung TL Chiu AW 《Journal of clinical microbiology》2003,41(10):4502-4511
Two hundred twenty isolates of Vibrio cholerae O1 and O139 collected from 1994 to 2002 in Hong Kong were analyzed by pulsed-field gel electrophoresis (PFGE). Chromosomal DNAs from all V. cholerae isolates in agarose plugs were digested with the restriction enzyme NotI, resulting in 20 to 27 bands. Sixty distinctive PFGE patterns in the range of 10 to 300 kb were noted among 213 isolates typeable by PFGE. By comparing the common PFGE patterns obtained from four well-defined outbreaks of V. cholerae O1 and O139 with those obtained from other, epidemiologically unrelated isolates during the study period, indistinguishable and similar PFGE patterns were identified, indicating their close relatedness, in agreement with the results of epidemiological investigations. Heterogeneous PFGE patterns (with four to six banding differences), however, were identified among strains that were imported from other parts of Asia, including Indonesia, India, and Pakistan. Correlations with epidemiological information further support the usefulness of PFGE as an epidemiological tool in laboratory investigations of suspected outbreaks. Standardization of PFGE methodology will allow international comparison of fingerprint patterns and will form the basis of a laboratory network for tracking V. cholerae. 相似文献
45.
Suppression of charge movement in frog skeletal muscle by D600 总被引:2,自引:0,他引:2
Summary Charge movements in intact frog twitch fibres were studied using a three-microelectrode voltage-clamp technique. When high potassium solution was applied transiently to the muscle fibres at low temperature in the presence of D600, the fibres became paralysed and, concomitantly, charge movement disappeared. The amount of charge suppressed by the paralysis treatment was about 70–100% of that in control experiments. This paralysing action of D600 is not shared by its derivative D890. The requirement of conditioning potassium contracture is, most likely, related to prolonged membrane depolarization, as voltage-clamped depolarization to 0 mV lasting tens of seconds also suppressed charge movement. When paralysed fibres were warmed, the main charge component (Q
) was reprimed. By contrast, the hump charge component (Q
was only reprimed in some of the fibres. Other than by warming, as paralysed fibre could be revived by stimulating it with large suprathreshold pulses but not by voltage-clamped hyperpolarization to –160 mV for tens of seconds. The paralysing action of D600 described here appears to be unrelated to its ability in blocking Ca2+ channels. 相似文献
46.
Krushkal J; Xiong M; Ferrell R; Sing CF; Turner ST; Boerwinkle E 《Human molecular genetics》1998,7(9):1379-1383
Elevated blood pressure is an important risk factor for renal-, cerebro-
and cardiovascular diseases. We used an efficient discordant sib-pair
ascertainment scheme to investigate the impact of the distal end of the
long arm of human chromosome 5 (chromosomal region 5q31.1-qter) containing
genes for the alpha1B and beta2 adrenergic receptors and the dopamine
receptor type 1A on variation of systolic blood pressure in young
Caucasians. We measured eight highly polymorphic markers spanning this
positional candidate gene-rich region in 427 individuals from 55
three-generation pedigrees containing 69 discordant sibling pairs, and
calculated multipoint identity by descent (MIBD) probabilities. The results
of genetic linkage and association tests indicate that the region between
markers D5S2093 and D5S462 is significantly linked to one or more
polymorphic genes influencing interindividual variation in systolic blood
pressure levels. Since the alpha1B adrenergic receptor and dopamine
receptor type 1A genes are located close to these markers, these data
suggest that genetic variation in one or both of these G protein-coupled
receptors, which participate in the control of vascular tone, plays an
important role in influencing interindividual variation in systolic blood
pressure levels.
相似文献
47.
Molyneux G Gibson FM Gordon-Smith EC Pilling AM Liu KC Rizzo S Sulsh S Turton JA 《International journal of experimental pathology》2005,86(6):415-430
Mitomycin (MMC), like many antineoplastic drugs, induces a predictable, dose-related, bone marrow depression in man and laboratory animals; this change is generally reversible. However, there is evidence that MMC may also cause a late-stage or residual bone marrow injury. The present study in female CD-1 mice investigated the haematological and bone marrow changes induced by MMC in a repeat dose study lasting 50 days. Control and MMC-treated mice were dosed intraperitoneally on eight occasions over 18 days with vehicle, or MMC at 2.5 mg/kg, autopsied (n = 6-12) at 1, 7, 14, 28, 42 and 50 days after the final dose and haematological changes investigated. Femoral nucleated bone marrow cell counts and levels of apoptosis were also evaluated and clonogenic assays carried out; serum levels of FLT3 ligand (FL) were assessed. At day 1 post-dosing, MMC induced significant reductions in RBC, Hb and haematocrit (HCT) values, and there were decreases in reticulocyte, platelet, and femoral nucleated cell counts (FNCC); neutrophil, lymphocyte and monocyte values were also significantly reduced. On days 7 and 14 post-dosing, all haematological parameters showed evidence of a return towards normal values, but at these times, and at day 28, values for RBC and FNCC remained significantly reduced in comparison with controls. At days 42 and 50 post-dosing, many haematological parameters in MMC-treated mice had returned to control levels; however, there remained evidence of late-stage effects on RBC, Hb and HCT values, and FNCC also continued to be significantly decreased. Results for granulocyte-macrophage colony-forming units and erythroid colonies showed a profound decrease immediately post-dosing, but a return to normal values was evident at day 50. Serum FL concentrations demonstrated very significant increases in the immediate post-dosing period, but a return to normal was seen at day 50 post-dosing; a relatively similar pattern was seen in the number of apoptotic femoral marrow nucleated cells. The histopathological examination of kidney tissues from MMC animals at day 42 and 50 post-dosing showed evidence of hydronephrosis with cortical glomerular/tubular atrophy and degeneration. It is therefore concluded that MMC administered on eight occasions over 18 days to female CD-1 mice at 2.5 mg/kg induced profound changes in haematological and bone marrow parameters in the immediate post-dosing period with a return to normal levels at day 50 post-dosing; however, there was evidence of mild but significant late-stage/residual effects on RBC and FNCC, and on cells of the erythroid lineage in the bone marrow. 相似文献
48.
Chiu TT Rogers MS Law EL Briton-Jones CM Cheung LP Haines CJ 《Human reproduction (Oxford, England)》2002,17(6):1591-1596
BACKGROUND: The follicular microenvironment is an important determinant of oocyte development. The aim of this study was to examine whether the myo-inositol (MI) content in human follicular fluid (FF) was associated with better oocyte quality. METHODS: A total of 53 patients treated with IVF was recruited to a prospective observational study. FF and serum samples collected were divided into two groups: group A consisted of FF associated with matured and fertilized oocytes, whilst group B was from follicles with immature and unfertilized oocytes. RESULTS: Patient's age, total ampoules of HMG used, days of stimulation, basal levels of FSH, estradiol (E(2)) levels on the day of HCG, and serum MI content were not significantly different between the two groups. FF volume and its MI content were significantly higher in group A compared with group B (P < 0.05). The levels of MI in FF were positively correlated with the amount of E(2) in their corresponding FF samples and also correlated with embryo quality. CONCLUSIONS: We propose that higher concentrations of MI and E(2) in human FF appear to play a role in follicular maturity and provide a marker of good quality oocytes. 相似文献
49.
Chuen -Mao Yang Hui -Liang Tsao Chi -Tso Chiu Lir -Wan Fan Sheu -Meei Yu 《Pflügers Archiv : European journal of physiology》1996,432(4):708-716
The effects of increases in cellular adenosine 3′5′-cyclic monophosphate (cAMP) on 5-hydroxytryptamine-(5-HT-) induced generation
of inositol phosphates (IPs) and increases in intracellular Ca2+ ([Ca2+]i) were investigated using canine cultured tracheal smooth muscle cells (TSMCs). Cholera toxin and forskolin induced concentration-
and time-dependent cAMP formation with half-maximal effects (−logEC50) produced at concentrations of 7.0 ± 0.5 and 4.9 ± 0.4 respectively. Pretreatment of TSMCs with either forskolin or dibutyryl
cAMP inhibited 5-HT-stimulated responses. Even after treatment for 24h, these agents still inhibited the 5-HT-induced Ca2+ mobilization. The inhibitory effects of these agents produced both depression of the maximal response and a shift to the
right of the concentration response curves of 5-HT. The water-soluble forskolin analogue L-858051 [7-deacetyl-7β-(γ-N-methylpiperazino)-butyryl forskolin] significantly inhibited the 5-HT-stimulated accumulation of IPs. In contrast, the addition
of 1,9-dideoxy forskolin, an inactive forskolin analogue, had little effect on this response. Moreover, SQ-22536 [9-(tetrahydro-2-furanyl)-9-H-purin-6-amine], an inhibitor of adenylate cyclase, and both H-89 [N-(2-aminoethyl)-5-isoquinolinesulphonamide] and HA-1004[N-(2-guanidinoethyl)-5-isoquinolinesulphonamide], inhibitors of cAMP-dependent protein kinase (PKA), attenuated the ability
of forskolin to inhibit the 5-HT-stimulated accumulation of IPs. These results suggest that activation of cAMP/PKA was involved
in these inhibitory effects of forskolin. The AlF4
−-induced accumulation of IPs was inhibited by forskolin, suggesting that G protein(s) are directly activated by AlF4
−- and uncoupled from phospholipase C by forskolin treatment. These results suggest that activation of cAMP/PKA might inhibit
the 5-HT-stimulated phosphoinositide breakdown and consequently reduce the [Ca2+]i increase or inhibit both responses independently.
Received: 14 March 1996/Accepted: 10 April 1996 相似文献
50.
INTRODUCTIONAdultRespiratoryDistressSyndrome(ARDS)isanacuteprogressiverespiratoryfailurecausedbymanyreasons.Thetherapeuticactionofthissyndromeisuncertain,becausethemechanismisnotwellknown.Thatis,theprognosisiscritical,themortailityisquiteheigh(50%f)ti--63'Butintherecenttenyears,manyscholarsinourcountryhavehadmuchexperienceintheaspectofusinganisodaminetorescueARDSpatientsandhavedecreasedthemortality(')'Howeveverthescholarsexplaintheprincipleofitindifferentways'Thechangesofmicrovascula… 相似文献