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排序方式: 共有714条查询结果,搜索用时 15 毫秒
1.
2.
Protective cytotoxic T lymphocyte responses against paramyxoviruses induced by epitope-based DNA vaccines: involvement of IFN-gamma 总被引:1,自引:0,他引:1
Hsu SC; Obeid OE; Collins M; Iqbal M; Chargelegue D; Steward MW 《International immunology》1998,10(10):1441-1447
Plasmid DNA vectors have been constructed with minigenes encoding a single
cytotoxic T lymphocyte (CTL) epitope from either the M2 protein of
respiratory syncytial virus (RSV) or from the nucleoprotein of measles
virus (MV) with or without a signal sequence (also called secretory or
leader sequence). Following intradermal immunization, plasmids in which the
CTL epitopes were expressed in-frame with the signal sequence were more
effective at inducing peptide- and virus- specific CTL responses than
plasmids expressing CTL epitopes without the signal sequence. This
immunization resulted in protection against MV-induced encephalitis and a
significant reduction in viral load following RSV challenge. The reduction
of viral load following RSV challenge was abrogated by prior injection with
anti-IFN-gamma antibodies. These results highlight the ability of
epitope-based DNA immunization to induce protective immune responses to
well-defined epitopes and indicate the potential of this approach for the
development of vaccines against infectious diseases.
相似文献
3.
4.
Quantitative analysis of MDR1 (multidrug resistance) gene expression in human tumors by polymerase chain reaction. 总被引:67,自引:6,他引:67 下载免费PDF全文
K E Noonan C Beck T A Holzmayer J E Chin J S Wunder I L Andrulis A F Gazdar C L Willman B Griffith D D Von Hoff et al. 《Proceedings of the National Academy of Sciences of the United States of America》1990,87(18):7160-7164
The resistance of tumor cells to chemotherapeutic drugs is a major obstacle to successful cancer chemotherapy. In human cells, expression of the MDR1 gene, encoding a transmembrane efflux pump (P-glycoprotein), leads to decreased intracellular accumulation and resistance to a variety of lipophilic drugs (multidrug resistance; MDR). The levels of MDR in cell lines selected in vitro have been shown to correlate with the steady-state levels of MDR1 mRNA and P-glycoprotein. In cells with a severalfold increase in cellular drug resistance, MDR1 expression levels are close to the limits of detection by conventional assays. MDR1 expression has been frequently observed in human tumors after chemotherapy and in some but not all types of clinically refractory tumors untreated with chemotherapeutic drugs. We have devised a highly sensitive, specific, and quantitative protocol for measuring the levels of MDR1 mRNA in clinical samples, based on the polymerase chain reaction. We have used this assay to measure MDR1 gene expression in MDR cell lines and greater than 300 normal tissues, tumor-derived cell lines, and clinical specimens of untreated tumors of the types in which MDR1 expression was rarely observed by standard assays. Low levels of MDR1 expression were found by polymerase chain reaction in most solid tumors and leukemias tested. The frequency of samples without detectable MDR1 expression varied among different types of tumors; MDR1-negative samples were most common among tumor types known to be relatively responsive to chemotherapy. 相似文献
5.
H L Kennedy S M Seiler M K Sprague S M Homan J A Whitlock M J Kern M G Vandormael H B Barner J E Codd V L Willman 《The American journal of cardiology》1990,65(1):14-22
The prevalence and characteristics of silent myocardial ischemia as detected by 24-hour ambulatory electrocardiography ST-segment depression were prospectively assessed in 94 patients examined early (1 to 3 months) and 184 patients examined late (12 months) after coronary artery bypass grafting (CABG), and followed for a mean of 48 +/- 11 (range 4 to 62) months. The relation of ambulatory electrocardiographic silent ischemia to evidence of completeness of revascularization as defined by cardiac angiography performed 1 and 12 months after CABG, and to prognosis by follow-up of adverse clinical events was analyzed. Silent ischemia was detected early in 20% (19 of 94) and late in 27% (50 of 184) of patients, and showed a mean frequency of episodes ranging from 6 to 10 episodes/24 hours with a mean duration ranging from 15 to 23 minutes. The circadian distribution of episodes disclosed a significant peak of ischemic activity during the period of 6 A.M. to noon and a secondary peak between 6 P.M. and midnight (p less than 0.01 and p less than 0.001, respectively). Silent ischemia was not found by univariate analysis to be associated with graft or anastomotic site occlusions, low graft flow rates, grafted arteries with significant distal residual stenoses or ungrafted stenotic native coronary arteries. Kaplan-Meier analysis of time to cardiac event showed that silent ischemia was not predictive of an adverse clinical event in the early years after CABG. Cox regression analysis of 30 covariates only disclosed age (relative risk 1.06 [95% confidence interval, 1.01 to 2.94]) as having an effect on time to adverse clinical event.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
6.
7.
J R Weiss K J Kopecky J Godwin J Anderson C L Willman K B Moysich M L Slovak A Hoque C B Ambrosone 《Leukemia》2006,20(12):2169-2171
8.
A DNA endonuclease, isolated from the nuclei of normal human and xeroderma
pigmentosum complementation group A (XPA) cells, which recognizes
predominately pyrimidine dimers, was examined for the mechanism by which it
locates sites of damage on UVC-irradiated DNA. In reaction mixtures with
low ionic strengths (i.e. lacking KCl), the normal and XPA endonuclease
locate sites of UV damage on both naked and reconstituted nucleosomal DNA
by different mechanisms. On both of these substrates, the normal
endonuclease acts by a processive mechanism, meaning that it binds
non-specifically to DNA and scans the DNA for sites of damage, whereas the
XPA endonuclease acts by a distributive one, meaning that it randomly
locates sites of damage on DNA. However, while both the normal and XPA
endonucleases can incise UVC irradiated naked DNA, they differ in ability
to incise damaged nucleosomal DNA. The normal endonuclease showed increased
activity on UVC treated nucleosomal DNA compared with naked DNA, whereas
the XPA endonuclease showed decreased activity on the damaged nucleosomal
substrate. Since a processive mechanism of action is sensitive to the ionic
strength of the micro-environment, the KCl concentration of the reaction
was increased. At 70 mM KCI, the normal endonuclease switched to a
distributive mechanism of action and its ability to incise damaged
nucleosomal DNA also decreased. These studies show that there is a
correlation between the ability of these endonucleases to act by a
processive mechanism and their ability to incise damaged nucleosomal DNA;
the normal endonuclease, which acts processively, can incise damaged
nucleosomal DNA, whereas the XPA endonuclease, which acts distributively,
is defective in ability to incise this substrate.
相似文献
9.
Epidemiological evidence indicates that aflatoxin B1 (AFB1) intake is
associated with an increased risk of hepatocellular carcinoma (HCC). The
hepatocarcinogenesis is initiated by covalent binding of AFB1 to cellular
DNA. To determine whether nutritional factors and hormonal status may
influence the binding of AFB1 to hepatic DNA, a cross- sectional study was
performed on a total of 42 male asymptomatic hepatitis B surface antigen
(HBsAg) carriers and 43 male non-carriers in a cohort study on the
multistage development of HCC in Taiwan. The major AFB1-DNA adduct in vivo,
AFB1-N7-guanine, was measured by high- performance liquid chromatography in
urine. Urinary AFB1-N7-guanine was detectable in 40% of the subjects. HBsAg
carriers had a higher detection rate of urinary AFB1-DNA adducts than
non-carriers and the difference was statistically significant after
multivariate adjustment. After taking into account the total AFB1 urinary
metabolite level, chronic HBsAg carrier status, and other potential
confounders, plasma levels of cholesterol, alpha-tocopherol, and alpha- and
beta-carotene were positively associated with the detection rate of the
AFB1-DNA adducts in a dose-dependent manner, whereas plasma lycopene level
was inversely related to the presence of the adducts in urine. The
association of urinary AFB1-DNA adducts with the plasma levels of
cholesterol, alpha-tocopherol, lycopene, and alpha- and beta-carotene was
observed at both low and high exposure levels of AFB1. There was a
synergistic interaction of plasma alpha-tocopherol with alpha- and beta-
carotene on the adduct levels. No association with the adducts was found
for plasma levels of retinol and testosterone. This study demonstrated
different associations of antioxidant vitamins with AFB1- DNA adduct
formation. The data consistent with our previous finding in cultured
woodchuck hepatocytes that alpha-tocopherol and beta-carotene enhanced
AFB1-DNA adduct formation suggest that prospective investigation of the
relationship between plasma micronutrients and risk of AFB1-related HCC is
warranted.
相似文献
10.
LO Larsson MW Bentzon K Berg Kelly L Mellander B-E Skoogh I-L Strannegård A Lind 《Acta paediatrica (Oslo, Norway : 1992)》1994,83(10):1091-1094
We studied 3592 Swedish schoolchildren, 8 or 9 years old, examined for palpable submandibular, cervical and supraclavicular lymph nodes. All children were skin tested with 2 TU PPD RT23 and with 0.1 μ g of Mycobacterium avium sensitin or 0.1 μ g of M. scrofulaceum sensitin. A total of 991 children had palpable lymph nodes in any of the three locations. Among them, 811 had lymph nodes in one location, 162 in two locations and 18 in three. In 312 children, the lymph nodes were ± 5 mm in size in any location. The most common location was submandibular. Boys had a significantly higher prevalence of palpable lymph nodes than girls. There was also seasonal variation. Children infected by atypical mycobacteria (sensitin reaction ±6 mm) did not have a higher prevalence of palpable lymph nodes than those not infected. 相似文献