首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   16篇
  完全免费   7篇
  2017年   1篇
  2016年   1篇
  2015年   1篇
  2014年   1篇
  2012年   1篇
  2010年   1篇
  2008年   2篇
  2007年   2篇
  2004年   4篇
  2003年   1篇
  2002年   1篇
  1999年   1篇
  1998年   1篇
  1994年   1篇
  1993年   2篇
  1982年   1篇
  1975年   1篇
排序方式: 共有23条查询结果,搜索用时 62 毫秒
1.
We have probed the structure of the C4 and V3 domains of human immunodeficiency virus type 1 gp120 by immunochemical techniques. Monoclonal antibodies (MAbs) recognizing an exposed gp120 sequence, (E/K)VGKAMYAPP, in C4 were differentially sensitive to denaturation of gp120, implying a conformational component to some of the epitopes. The MAbs recognizing conformation-sensitive C4 structures failed to bind to a gp120 mutant with an alteration in the sequence of the V3 loop, and their binding to gp120 was inhibited by both V3 and C4 MAbs. This implies an interaction between the V3 and C4 regions of gp120, which is supported by the observation that the binding of some MAbs to the V3 loop was often enhanced by amino acid changes in an around the C4 region.  相似文献
2.
We have analyzed a panel of eight murine monoclonal antibodies (MAbs) that depend on the V2 domain for binding to human immunodeficiency virus type 1 (HIV-1) gp120. Each MAb is sensitive to amino acid changes within V2, and some are affected by substitutions elsewhere. With one exception, the MAbs were not reactive with peptides from the V2 region, or only poorly so. Hence their ability to bind recombinant strain IIIB gp120 depended on the preservation of native structure. Three MAbs cross-reacted with strain RF gp120, but only one cross-reacted with MN gp120, and none bound SF-2 gp120. Four MAbs neutralized HIV-1 IIIB with various potencies, and the one able to bind MN gp120 neutralized that virus. Peptide serology indicated that antibodies cross-reactive with the HxB2 V1 and V2 regions are rarely present in HIV-1-positive sera, but the relatively conserved segment between the V1 and V2 loops was recognized by antibodies in a significant fraction of sera. Antibodies able to block the binding of V2 MAbs to IIIB or MN gp120 rarely exist in sera from HIV-1-infected humans; more common in these sera are antibodies that enhance the binding of V2 MAbs to gp120. This enhancement effect of HIV-1-positive sera can be mimicked by several human MAbs to different discontinuous gp120 epitopes. Soluble CD4 enhanced binding of one V2 MAb to oligomeric gp120 but not to monomeric gp120, perhaps by inducing conformational changes in the oligomer.  相似文献
3.
The reactivities of a panel of 14 monoclonal antibodies (MAbs) with monomeric gp120 derived from 67 isolates of human immunodeficiency virus type 1 of clades A through F were assessed by using an antigen-capture enzyme-linked immunosorbent assay. The MAbs used were all raised against gp120 or gp120 peptides from clade B viruses and were directed at a range of epitopes relevant to human immunodeficiency virus type 1 neutralization: the V2 and V3 loops, discontinuous epitopes overlapping the CD4-binding site, and two other discontinuous epitopes. Four of the five V3 MAbs showed modest cross-reactivity within clade B but very limited reactivity with gp120s from other clades. These reactivity patterns are consistent with the known primary sequence requirements for the binding of these MAbs. One V3 human MAb (19b), however, was much more broadly reactive than the others, binding to 19 of 29 clade B and 10 of 12 clade E gp120s. The 19b epitope is confined to the flanks of the V3 loop, and these sequences are relatively conserved in clade B and E viruses. In contrast to the limited reactivity of V3 MAbs, CD4-binding site MAbs were much more broadly reactive across clades, two of these MAbs (205-46-9 and 21h) being virtually pan-reactive across clades A through F. Another human MAb (A-32) to a discontinuous epitope was also pan-reactive. The CD4-binding site is strongly conserved between clades; but when considering the epitopes near the CD4-binding site, clade D gp120 appears to be the most closely related to clade B and clade E appears to be the least related. A tentative rank order for these epitopes is B/D-A/C-E/F. V2 MAbs reacted sporadically within and between clades, and no clear pattern was observable. While results from binding assays do not predict neutralization serotypes, they suggest that there may be antigenic subtypes related, but not identical, to the genetic subtypes.  相似文献
4.
Lambdoid Coliphage HK139 Integrates Between his and supD   总被引:1,自引:0,他引:1       下载免费PDF全文
Phage HK139 is UV inducible and lambda homoimmune and has the host range of phi80. It can recombine with lambda as well as with phi80, and in the prophage form it is found integrated between the loci his and supD.  相似文献
5.
The objective of this study is to develop a portable device for quantifying the velocity-dependent properties of spastic elbow muscles. Based on a motor-driven system, validation tests of the portable system such as accuracy and response of sensors were first examined. Furthermore, simulated modules (inertia, damper and spring) as well as elbow joints (15 control and 15 hemiplegic subjects) were manually stretched under four different frequencies (1/3, 1/2, 1 and 3/2 Hz) through 60 degrees range of motion. Joint resistance and displacement during sinusoidal stretch were collected for further analysis. Two quantitative parameters (i.e., viscous components under each frequency and averaged viscosity across four frequencies) were derived to estimate the velocity-dependent properties of elbow joint. Tests of simulated modules confirm the manual stretch protocol and data analysis are valid in estimating the velocity-dependent component during a sinusoidal stretch. Compared to normal control, viscous component in each stretch frequency and averaged viscosity were significantly higher in subjects with spasticity (P < 0.001). The viscous component and averaged viscosity were found highly correlated with the modified Ashworth scale. These findings suggest that measurements of viscous component and averaged viscosity during manual sinusoidal stretching using the portable device could be clinically useful in evaluating spasticity.  相似文献
6.
The coding domain of the herpes simplex virus type 1 (HSV-1) alpha22 gene encodes two proteins, the 420-amino-acid infected-cell protein 22 (ICP22) and U(S)1.5, a protein colinear with the carboxyl-terminal domain of ICP22. In HSV-1-infected cells, ICP22 and U(S)1.5 are extensively modified by the U(L)13 and U(S)3 viral protein kinases. In this report, we show that in contrast to other viral proteins defined by their properties as alpha proteins, U(S)1.5 becomes detectable and accumulated only at late times after infection. Moreover, significantly more U(S)1.5 protein accumulated in cells infected with a mutant lacking the U(L)13 gene than in cells infected with wild-type virus. To define the role of viral protein kinases on the accumulation of U(S)1.5 protein, rabbit skin cells or Vero cells were exposed to recombinant baculoviruses that expressed U(S)1.5, U(L)13, or U(S)3 proteins under a human cytomegalovirus immediate-early promoter. The results were as follows. (i) Accumulation of the U(S)1.5 protein was reduced by concurrent expression of the U(L)13 protein kinase and augmented by concurrent expression of the U(S)3 protein kinase. The magnitude of the reduction or increase in the accumulation of the U(S)1.5 protein was cell type dependent. The effect of U(L)13 kinase appears to be specific inasmuch as it did not affect the accumulation of glycoprotein D in cells doubly infected by recombinant baculoviruses expressing these genes. (ii) The reduction in accumulation of the U(S)1.5 protein was partially due to proteasome-dependent degradation. (iii) Both U(S)1.5 and U(L)13 proteins activated caspase 3, indicative of programmed cell death. (iv) Concurrent expression of the U(S)3 protein kinase blocked activation of caspase 3. The results are concordant with those published elsewhere (J. Munger and B. Roizman, Proc. Natl. Acad. Sci. USA 98:10410-10415, 2001) that the U(S)3 protein kinase can block apoptosis by degradation or posttranslational modification of BAD.  相似文献
7.
Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) has been recently used to identify disease markers by directly profiling and quantifying the peptide/proteins in biological samples under different physiological or experimental conditions. The information of reproducibility of such quantitative profiling method has not been available. It is important to evaluate and reduce error from technical variation. In this study, an unbiased signal acquisition strategy was used to evaluate the effects of three sample-matrix spotting methods and two matrix chemicals, α-cyano-4-hydroxycinnamic acid (CHCA) and sinapinic acid, on the reproducibility of the peptide/protein signal intensities. The sandwich spotting method using 0.1% nitrocellulose coating film and CHCA gave the best quantitative results for the standard peptides and proteins with mass<66.5 kDa. The normalized signal intensities of the standard peptides and proteins were directly proportional to their concentrations with intra-assay (within-day) coefficient of variations (CVs) ranging from 6.5% to 17%. When analyzing serum peptides <6000 m/z, the interassay (between-days) CVs of all the evaluated peptide peaks were <15%. These data indicate that with the right MS analysis conditions, MALDI-TOF MS appears to be a feasible tool for directly profiling and quantifying the peptide/ proteins in biological samples.  相似文献
8.
Although most patients with early-stage nasopharyngeal carcinoma (NPC) can be cured by radiotherapy, there is a high recurrence rate in patients with advanced NPC. We attempted to identify proteomic patterns in sera for predicting tumor recurrence. Pretreatment sera were collected from 64 NPC patients with complete remission after radiotherapy. Serum proteins were profiled by SELDI ProteinChip technology, and correlated with local/distant recurrence. Forty proteomic features were significantly different between the patient groups with and without tumor recurrence. Univariate analyses showed that 32 of them were significantly associated with time to first recurrence. Multivariate Cox-regression analyses identified International Union Against Cancer (UICC) stage and two proteomic features with mass/charge (m/z) values of 8808 and 6626 as independent prognostic indicators for tumor recurrence. The hazard ratios were 2.0 (95% confidence interval, CI 1.3–3.2) and 0.79 (95% CI 0.64–0.96) for a double of peak intensity of proteomic feature m/z 8808 and m/z 6626, respectively. These two proteomic features were also independent prognosticators for overall survival. A decision tree was constructed to predict the tumor recurrence by using UICC stage, proteomic feature m/z 8808, and proteomic feature m/z 6626, and evaluated by Leave-One-Out crossvalidation. Kaplan-Meier analysis confirmed that the decision tree could predict both recurrencefree survival and overall survival. The positive and negative predictive values for tumor recurrence within 4 yr were 74 and 89%, respectively. A serum proteomic pattern comprising features m/z 8808 and m/z 6626 is a potential surrogate marker of disease recurrence after radiotherapy in NPC.  相似文献
9.
10.
DNA frayed wires are a novel, multistranded form of DNA that arises from interactions between single-stranded oligodeoxyribonucleotides with the general sequence d(N(x)G(y)) or d(G(y)N(x)), where y > 10 and x > 5. Frayed wires exhibit greater stability with respect to thermal and chemical denaturation than single- or double-stranded DNA molecules and, thus, may have potential usefulness for DNA drug delivery. However, the stability and uptake of frayed wires have not been investigated in biological systems. Our objective was to examine the cellular uptake and stability of frayed wires in cultured hepatic cells. In these studies, the parent oligonucleotide d(A(15)G(15)) was used to form DNA frayed wires (DNA(FW)) while a random 30-mer oligonucleotide was used as the control nonaggregated DNA (DNA(SS)). Uptake and metabolism studies of DNA(FW) were performed in cultured human hepatoma, HepG2 cells and compared to DNA(SS). Our results indicate that DNA(FW) are not cytotoxic and that their intracellular uptake in HepG2 cells is 2-3.5-fold greater than that of DNA(SS) within the first 2 h (p < 0.05). Similarly, nuclear localization of DNA(FW) is 10-13-fold higher than that of DNA(SS) (p < 0.05). As both internalized and extracellular DNA(FW) appear to be more stable in vitro than DNA(SS), the enhanced uptake may be due to either increased stability or enhanced intracellular transport. These studies also indicate that uptake of DNA(FW) likely occurs via active processes such as receptor-mediated endocytosis similar to mechanisms which have been proposed for DNA(SS). The internalization pathways of DNA(FW) may differ somewhat from that of DNA(SS) insofar as chloroquine does not appear to alter DNA(FW) uptake and degradation, as is the case with DNA(SS).  相似文献
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号