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排序方式: 共有293条查询结果,搜索用时 15 毫秒
1.
Elizabeth A. Grimm William L. Crump III April Durett Jeane P. Hester Sandhya Lagoo-Deenadalayan Laurie B. Owen-Schaub 《Cancer immunology, immunotherapy : CII》1988,27(1):53-58
Summary Employing serum-free media, human peripheral blood mononuclear cells, and purified recombinant interleukin-2 (IL-2), conditions were observed in which the development of IL-2-driven cytotoxic activity was suppressed. The cytotoxic activity of such IL-2-generated lymphokine activated killing (LAK) was tested against natural killer-resistant cultured tumor cells (Daudi, Raji, and a glioma). LAK generation was inhibited by addition of some normal sera, normal platelets, or some tumor cells. Because recent reports have indicated that transforming growth factor-beta (TGF-beta)-like factors are often secreted by tumors and the acidic alpha granules of platelets and can be present in sera, we tested the effect of purified human TGF-beta on the activation of LAK. Our results indicated that TGF-beta is very suppressive for LAK induction, and can completely prevent both the IL-2-driven proliferation and cytotoxicity at concentrations as low as 5 ng/ml. Titrations of IL-2 and of TGF-beta indicated that the suppression is dose-dependent and can be avoided by employing higher levels of IL-2. It was also found that the suppressive effect of TGF-beta can be overcome by washing suppressed cell populations and further culture in low levels of IL-2. Collectively, these data indicate that TGF-beta can be a potent inhibitor of LAK generation under standard activation conditions, but that this effect is regulated by the relative level of IL-2 and may be overcome and/or reversed in vitro. 相似文献
2.
Anonymous nuclear DNA markers in the American oyster and their implications for the heterozygote deficiency phenomenon in marine bivalves 总被引:4,自引:0,他引:4
A puzzling population-genetic phenomenon widely reported in allozyme
surveys of marine bivalves is the occurrence of heterozygote deficits
relative to Hardy-Weinberg expectations. Possible explanations for this
pattern are categorized with respect to whether the effects should be
confined to protein-level assays or are genomically pervasive and expected
to be registered in both protein- and DNA-level assays. Anonymous nuclear
DNA markers from the American oyster were employed to reexamine the
phenomenon. In assays based on the polymerase chain reaction (PCR), two
DNA-level processes were encountered that can lead to artifactual genotypic
scorings: (a) differential amplification of alleles at a target locus and
(b) amplification from multiple paralogous loci. We describe symptoms of
these complications and prescribe methods that should generally help to
ameliorate them. When artifactual scorings at two anonymous DNA loci in the
American oyster were corrected, Hardy-Weinberg deviations registered in
preliminary population assays decreased to nonsignificant values.
Implications of these findings for the heterozygote-deficit phenomenon in
marine bivalves, and for the general development and use of PCR-based
assays, are discussed.
相似文献
3.
Marta Clariano Vanda Marques João Vaz Salma Awam Marta B. Afonso Maria Jesus Perry Cecília MP Rodrigues 《化学与生物多样性》2023,20(3):e202300222
Curcumin has a plethora of biological properties, making this compound potentially effective in the treatment of several diseases, including cancer. However, curcumin clinical use is compromised by its poor pharmacokinetics, being crucial to find novel analogs with better pharmacokinetic and pharmacological properties. Here, we aimed to evaluate the stability, bioavailability and pharmacokinetic profiles of monocarbonyl analogs of curcumin. A small library of monocarbonyl analogs of curcumin 1a–q was synthesized. Lipophilicity and stability in physiological conditions were both assessed by HPLC-UV, while two different methods assessed the electrophilic character of each compound monitored by NMR and by UV-spectroscopy. The potential therapeutic effect of the analogs 1a–q was evaluated in human colon carcinoma cells and toxicity in immortalized hepatocytes. Our results showed that the curcumin analog 1e is a promising agent against colorectal cancer, with improved stability and efficacy/safety profile. 相似文献
4.
B J Crump J E Cubbon M F Drummond R A Hawkes M D Marchment 《BMJ (Clinical research ed.)》1991,302(6792):1582-1584
OBJECTIVE--To estimate the financial effect of random yearly variations in need for services on fundholding practices with various list sizes. DESIGN--A simulation model was derived using historical data on general practitioner referrals for the 113 surgical procedures covered by the general practitioner fund, combined with data on the hospital prices for those procedures. PATIENTS--Resident population of Central Birmingham Health Authority. MAIN OUTCOME MEASURES--Expected expenditure on the relevant surgical procedures for the whole district and for practices with list sizes of 9000, 12,000, 15,000, 18,000, 21,000, or 24,000 for each of 100 simulated years. RESULTS--By using average hospital prices for the West Midlands region the mean (SD) annual expenditure for the 179,400 residents was 4,832,471 pounds (87,149 pounds); the random variation between the 5th and 95th most expensive years was 5.7% of the mean cost. For a practice with a list size of 9000 the values were 244,891 pounds (18,349 pounds), with a variation of 27.5%. With a list size of 24,000 the values were 652,762 pounds (32,512 pounds), with a variation of 15.3%. CONCLUSIONS--Random variations in need for inpatient services will have a significant financial impact on the practice fund. The problem will be particularly great for smaller practices. Additional measures are required to ensure that the scheme is not undermined and that the potential benefits are secured. 相似文献
5.
Data obtained from 423 individuals were analyzed for mode of inheritance of extra triradii on palmar interdigital area II and IV separately, and in combination. It indicates that a single dominant allele A for extra triradius in the area II, and an allele D in the area IV, may be responsible for the presence of the patterns in the respective area, with 75 to 80 per cent penetrance. There are numbers of individuals in which extra triradii are present in both interdigital areas II and IV. The mode of inheritance has been estimated from the data obtained and was found to have co-dominant alleles A and D for the presence in their respective areas. Further analysis revealed the existence of three alleles. A and D for presence, and 0 for absence. The alleles A and D are co-dominant, if combined in the genotype AD, but either allele is dominant in heterozygous combination with 0. 相似文献
6.
G Ghiselli W L Crump A M Gotto 《Biochemical and biophysical research communications》1986,139(1):122-128
Rat apoA-IV complexes with dimyristoyl phosphatidylcholine (apoA-IV-DMPC) have been prepared and their ability to bind to purified rat liver plasma membranes investigated. Binding equilibrium at 37 degrees C was reached in 30 minutes. Saturation binding experiments and subsequent analysis of the results with Scatchard plots gave results consistent with the presence of a single saturable binding site. DMPC or POPC unilamellar vesicles could not compete with apoA-IV-DMPC for binding; apoA-I-DMPC competed only partially. ApoE-poor HDL effectively competed with apoA-IV-DMPC. The fact that binding could be greatly reduced (greater than 70%) by preincubating the membrane with pronase (18 micrograms/ml), supports the conclusion that a membrane protein is involved in binding. Based on these results, we speculate that the rapid catabolism of apoA-IV in plasma may be mediated by a specific uptake mechanism in the liver. The implications of these results support the hypothesis that apoA-IV is involved in reverse cholesterol transport. 相似文献
7.
We have developed a specific and sensitive radioimmunoassay for rat apolipoprotein A-IV (apoA-IV). The protocol includes treatment of the samples for 1 h at 60 degrees C with 0.7% Tween 20. Under these conditions, linear logit-log plots have been obtained for apoA-IV in lymph and plasma lipoprotein fractions as well as for purified apoA-IV. The sensitivity of the assay is to 20 ng. Absolute mass values obtained with the assay were validated by comparison with values obtained with an independent method of colorimetric reading of apoA-IV separated by polyacrylamide gel electrophoresis from plasma high density lipoproteins. The concentration of apoA-IV in fasting plasma averaged 10.2 mg/dl and in the mesenteric duct lymph 15.8 and 12.6 mg/dl during the fasting and the fat absorption states, respectively. 相似文献
8.
Sampling properties of DNA sequence data in phylogenetic analysis 总被引:20,自引:6,他引:20
We inferred phylogenetic trees from individual genes and random samples of
nucleotides from the mitochondrial genomes of 10 vertebrates and compared
the results to those obtained by analyzing the whole genomes. Individual
genes are poor samples in that they infrequently lead to the whole-genome
tree. A large number of nucleotide sites is needed to exactly determine the
whole-genome tree. A relatively small number of sites, however, often
results in a tree close to the whole-genome tree. We found that blocks of
contiguous sites were less likely to lead to the whole-genome tree than
samples composed of sites drawn individually from throughout the genome.
Samples of contiguous sites are not representative of the entire genome, a
condition that violates a basic assumption of the bootstrap method as it is
applied in phylogenetic studies.
相似文献
9.
10.
Robert Gramling Kathi L Heffner William MP Klein Laura E Zajac Mary Roberts Charles B Eaton 《BioPsychoSocial medicine》2010,4(1):11