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排序方式: 共有216条查询结果,搜索用时 15 毫秒
1.
A new mouse TCR V gamma gene that shows remarkable evolutionary conservation. 总被引:15,自引:1,他引:14 下载免费PDF全文
We have identified a new mouse T-cell receptor V gamma gene segment, V gamma 4.4, which frequently undergoes rearrangements in AKR thymomas, and at a lower frequency in fetal thymocytes. V gamma 4.4 is the fourth and the most 5' V gene segment in the gamma 4 cluster, being 7.3 kb from V gamma 4.3. Surprisingly, V gamma 4.4 is more homologous to eight human V gamma genes than to the other mouse V gamma genes. It has only a 38% nucleotide and 21% amino acid sequence homology to the most homologous mouse V gamma gene (V gamma 4.1), whereas these homologies to the human V gamma 8 gene are as high as 68% and 48% respectively. 相似文献
2.
Dolores G. Evans Ph.D. Doyle J. Evans Jr. Tuomo K. Karjalainen Chao-Hung Lee 《Current microbiology》1991,23(2):71-74
Experiments were performed to study the effect of glucose on the production of the fimbrial colonization factor CFA/II of enterotoxigenicEscherichia coli (ETEC). The production of the CFA/II antigen was examined by electron microscopy, quantitative ELISA, and hemagglutination. The results showed that addition of 1% glucose to the growth medium drastically decreased CFA/II production, whereas addition of glycerol or sodium acetate did not have any effect. Bacteria grown in the presence of 1% glucose were essentially devoid of CFA/II fimbriae when examined under the electron microscope. Addition of 1 mM cAMP reversed the repressive effect of glucose, suggesting that the glucose suppression on CFA/II synthesis is via the mechanism of catabolite repression. 相似文献
3.
Abrogation of simian virus 40 DNA-mediated transformation of primary C57BL/6 mouse embryo fibroblasts by exposure to a simian virus 40-specific cytotoxic T-lymphocyte clone. 总被引:4,自引:3,他引:1 下载免费PDF全文
Primary mouse embryo fibroblasts of C57BL/6 origin (B6/MEF) were transformed in vitro by transfection with simian virus 40 (SV40) DNA. The transformation frequency was markedly reduced if the SV40 DNA-transfected cultures were briefly exposed to K11 cells, an SV40-specific clone of cytotoxic T lymphocytes. This abrogation of SV40 transformation in vitro by cytotoxic T-lymphocyte clone K11 was specific, since transformation of B6/MEF cells by adenovirus type 5 DNA was not affected. The approach described here should serve as an ideal model of dissecting immunological events during in vivo tumorigenesis. 相似文献
4.
Normal T cell development is possible without ''functional'' gamma chain genes. 总被引:15,自引:2,他引:13 下载免费PDF全文
The T cell-specific gamma gene family is organized into four V, J and C gene segments containing clusters (gamma 1, gamma 2, gamma 3, gamma 4) in germline DNA. We found that the V, J and C elements of gamma 2 are physically linked on a stretch of 6 kb of DNA while those of gamma 3 are found within a 15-kb region. Rearrangements take place only within the clusters, explaining the rigid rearrangement patterns seen in T lymphocytes. New V gamma, J gamma and C gamma gene segments were discovered and characterized allowing the better understanding of the potential germline diversity of the gamma gene family. No correlation with T cell function, i.e. cytolytic or helper, and the type of the productive gamma rearrangement could be established. In contrast we found that functional T cell clones have been able to mature without any functional gamma chain genes. 相似文献
5.
6.
OBJECTIVE--To determine whether patients with multiple myeloma treated in three consecutive clinical trials of chemotherapy of the Finnish Leukaemia Group during 1979-85 had a more favourable prognosis than both patients treated in the trial area before the trials and those treated in the rest of Finland. DESIGN--Comparison of the time trend in survival of patients living in the trial area with that of patients living in the rest of Finland. SETTING--Trial area covered 17 of the 21 main hospital districts in Finland (serving more than two thirds of patients with multiple myeloma). PATIENTS--663 Men and 690 women in the trial area and 318 men and 307 women in the reference area aged under 71 in whom multiple myeloma was diagnosed during 1959-85. In the trial area the disease was diagnosed in 455 men and 493 women in 1959-78 and in 208 men and 197 women in 1979-85; in the reference area it was diagnosed in 234 men and 227 women in 1959-78 and in 84 men and 80 women in 1979-85. MAIN OUTCOME MEASURES--Five year cumulative relative survival rates during 1959-85, annual relative survival rates in the first seven years of follow up during 1979-85, and fitted annual relative survival rates in the first five years of follow up during 1959-85. RESULTS--During the first two years of follow up the annual relative survival rates did not differ between the two areas, but in the next five years of follow up patients in the trial area did better than those in the reference area. For cases diagnosed in 1979-85 the difference in the five year cumulative relative survival rates between patients in the trial area and those in the reference area was 10%, those in the trial area doing better. Generalised proportional hazards regression analysis of the first five years of follow up showed that the patients in the trial area had a survival advantage over those in the reference area. The model with the best fit included year of follow up, time of diagnosis, the joint effect of year of follow up and time of diagnosis, and the joint effect of area and time of diagnosis. CONCLUSION--The patients in the trial area benefited from the clinical trials, which suggests that the use of a treatment protocol improves the end results of treatment. In other words, the results favour a systematic treatment schedule in preference to a schedule determined by the free choice of a clinician. 相似文献
7.
Phosphate and calcium uptake by mitochondria and by perfused rat liver induced by the synergistic action of glucagon and vasopressin. 下载免费PDF全文
F L Bygrave L Lenton J G Altin B A Setchell A Karjalainen 《The Biochemical journal》1990,267(1):69-73
Co-administration of glucagon and vasopressin to rat liver perfused with buffer containing 1.3 mM-Ca2+ induces a 4-fold increase in Pi in the subsequently isolated mitochondria (from approx. 9 to approx. 40 nmol/mg of mitochondrial protein). This increase is not attributable to PPi hydrolysis, and is not observed if the perfusate Ca2+ is lowered from 1.3 mM to 50 microM. The increase in mitochondrial Pi closely parallels that of mitochondrial Ca2+; when the increase in Pi and Ca2+ accumulation is maximal, the molar ratio is close to that in Ca3(PO4)2. Measurement of changes in the perfusate Pi revealed that, whereas administration of glucagon or vasopressin alone brought about a rapid decline in perfusate Pi, the largest decrease (reflecting net retention of Pi by the liver) was observed when the hormone was co-administered in the presence of 1.3 mM-Ca2+. The synergistic action of glucagon plus vasopressin was nullified by lowering the perfusate Ca2+ to 50 microM. The data provide evidence that, whereas glucagon may be able to alter Pi fluxes directly in intact liver, any alterations induced by vasopressin are indirect and result only from its action of mobilizing Ca2+. 相似文献
8.
The interactions between phytoplankton and zooplankton were studied in two large lakes in the Saimaa lake system, Finland. Both are subjected to substantial waste water loading, and exhibit a clear trophic gradient between the loaded and unloaded areas. The phytoplankton and zooplankton were compared in terms of composition, abundance and biomass at 34–39 stations located in different parts of the lakes. At least four mechanisms were thought to affect the composition of plankton communities: (1) the amount of nutrients (trophic gradient), (2) grazing of algae by herbivores, (3) the effect of the algal species composition on feeding by zooplankters (large, colonial algae in the more loaded parts of the lakes) and (4) the regeneration and reorganization of nutrients. 相似文献
9.
WhileEscherichia coli is common as a commensal organism in the distal ileum and colon, the presence of colonization factors (CF) on pathogenic strains ofE. coli facilitates attachment of the organism to intestinal receptor molecules in a species- and tissue-specific fashion. After the initial adherence, colonization occurs, and the involvement of additional virulence determinants leads to illness. EnterotoxigenicE. coli (ETEC) is the most extensively studied of the five categories ofE. coli that cause diarrheal disease, and has the greatest impact on health worldwide. ETEC can be isolated from domestic animals and humans. The biochemistry, genetics, epidemiology, antigenic characteristics, and cell and receptor binding properties of ETEC have been extensively described. Another major category, enteropathogenicE. coli (EPEC), has virulence mechanisms, primarily effacement and cytoskeletal rearrangement of intestinal brush borders, that are distinct from ETEC. An EPEC CF receptor has been purified and characterized as a sialidated transmembrane glycoprotein complex directly attached to actin, thereby associating CF-binding with host-cell response. Three, additional categories ofE. coli diarrheal disease, their colonization factors and their host cell receptors are discussed. It appears that biofilms exist in the intestine in a manner similar to oral bacterial biofilms, and thatE. coli is part of these biofilms as both commensals and pathogens.Abbreviations CF
colonization factor
- CFA
Colonization Factor Antigen
- CS
coli-surface-associated antigen
- EAggEC
enteroaggregativeE. coli
- ECDD
E. coli diarrheal disease
- EHEC
enterohemorrhagicE. coli
- EIEC
enteroinvasiveE. coli
- EPEC
enteropathogenicE. coli
- ETEC
enterotoxigenicE. coli
- Gal
galactose
- GalNAc
N-acetyl galactosamine
- LT
heat-labile toxin
- NeuAc
N-acetyl neuraminic acid
- PCF
Putative colonization factor
- RBC
red blood cells
- SLT
Shiga-like toxin
- ST
heat-stable toxin 相似文献
10.
The nuclear 18S, 5.8S and 25S rRNA genes exist as thousands of rDNA repeats in the Scots pine genome. The number and location
of rDNA loci (nucleolus organizers, NORs) were studied by cytological methods, and a restriction map from the coding region
of the Scots pine rDNA repeat was constructed using digoxigenin-labeled flax rDNA as a probe. Based on the maximum number
of nucleoli and chromosomal secondary constrictions, Scots pine has at least eight NORs in its haploid genome. The size of
the Scots pine rDNA repeat unit is approximately 27 kb, two- or threefold larger than the typical angiosperm rDNA unit, but
similar in size to other characterized conifer rDNA repeats. The intergenic spacer region (IGS) of the rDNA repeat unit in
Scots pine is longer than 20 kb, and the transcribed spacer regions surrounding the 5.8S gene (ITS1 and ITS2) span a region
of 2.9 kb. Restriction analysis revealed that although the coding regions of rDNA repeats are homogeneous, heterogeneity exists
in the intergenic spacer region between individuals, as well as among the rDNA repeats within individuals. 相似文献