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排序方式: 共有403条查询结果,搜索用时 31 毫秒
1.
Abstract: Native chemical ligation has proven to be a powerful method for the synthesis of small proteins and the semisynthesis of larger ones. The essential synthetic intermediates, which are C‐terminal peptide thioesters, cannot survive the repetitive piperidine deprotection steps of Nα‐9‐fluorenylmethoxycarbonyl (Fmoc) chemistry. Therefore, peptide scientists who prefer to not use Nα‐t‐butyloxycarbonyl (Boc) chemistry need to adopt more esoteric strategies and tactics in order to integrate ligation approaches with Fmoc chemistry. In the present work, side‐chain and backbone anchoring strategies have been used to prepare the required suitably (partially) protected and/or activated peptide intermediates spanning the length of bovine pancreatic trypsin inhibitor (BPTI). Three separate strategies for managing the critical N‐terminal cysteine residue have been developed: (i) incorporation of Nα‐9‐fluorenylmethoxycarbonyl‐S‐(N‐methyl‐N‐phenylcarbamoyl)sulfenylcysteine [Fmoc‐Cys(Snm)‐OH], allowing creation of an otherwise fully protected resin‐bound intermediate with N‐terminal free Cys; (ii) incorporation of Nα‐9‐fluorenylmethoxycarbonyl‐S‐triphenylmethylcysteine [Fmoc‐Cys(Trt)‐OH], generating a stable Fmoc‐Cys(H)‐peptide upon acidolytic cleavage; and (iii) incorporation of Nα‐t‐butyloxycarbonyl‐S‐fluorenylmethylcysteine [Boc‐Cys(Fm)‐OH], generating a stable H‐Cys(Fm)‐peptide upon cleavage. In separate stages of these strategies, thioesters are established at the C‐termini by selective deprotection and coupling steps carried out while peptides remain bound to the supports. Pilot native chemical ligations were pursued directly on‐resin, as well as in solution after cleavage/purification. 相似文献
2.
Secretion of a chemotactic factor for neutrophils and eosinophils by alveolar macrophages from asthmatic patients 总被引:10,自引:0,他引:10
Philippe Gosset Ph.C. AndrBernard Tonnel M.D. Michel Joseph Ph.D. Lionel Prin M.D. Anne Mallart M.D. Jacques Charon D.D.S. Andr Capron M.D. 《The Journal of allergy and clinical immunology》1984,74(6):827-834
The studies presented in this article demonstrate the release of an IgE-dependent chemotactic factor for polymorphonuclear neutrophils (PMN) and eosinophils by alveolar macrophages (AMs) from normal subjects (n = 15) and allergic asthmatic patients (n = 15). A 60-minute incubation of normal AMs previously sensitized by 20% nonheated allergic sera with anti-human IgE antibody or the related allergen induced the release of a chemotactic activity (CA) for PMN and eosinophils in culture supernatants. When AMs were obtained from asthmatic patients, direct incubation with anti-IgE or the related allergen induced the same CA, whereas incubation with an unrelated allergen failed to produce CA (neutrophil CA after addition of anti-IgE, 22.5 +/- 3.5 cells per high power field; with related allergen, 15.8 +/- 3.6; with unrelated allergen, 0.7 +/- 1.8; p less than 0.0001). A partial characterization of the neutrophil chemotactic factor was carried out. Enzymatic treatment by trypsin or carboxypeptidase or by heating (56 degrees C for 3 hr) failed to abolish the neutrophil CA. After gel filtration the greater part of the neutrophil CA (80%) was recovered among low-molecular-weight components (300 to 1300 daltons). A preliminary deactivation of PMN by leukotriene B4 suppressed the CA of AM supernatants. These results indicate that IgE-dependent stimulation of AMs produces a neutrophil and eosinophil CA, present in a low-molecular-weight fraction possibly related to leukotrienes, and emphasizes the role of AMs in inflammatory lung processes during allergic asthma. 相似文献
3.
Albertini-Yagi CS Oliveira RC Vieira JE Negri EM de Oliveira LR Saldiva PH Lorenzi-Filho G 《Respiratory physiology & neurobiology》2005,145(1):101-110
The study objectives were to compare in vitro transportability and physical properties of respiratory mucus, obtained invasively by direct collection (DC) right after endotracheal intubation and non-invasively by sputum induction with 3% hypertonic saline solution inhalation (SI) 24 h before the anesthesia. Twenty-two patients with no pulmonary disease scheduled for elective abdominal surgical procedures were studied. The parameters analyzed and the main results are as follows. (1) Transportability by cilia (MCT), SI was higher than DC (0.94+/-0.25 and 0.62+/-0.25; P<0.001). There was a significant correlation between the two methods and DC could be estimated by: DC=0.21+(0.44 SI) (r=0.44; P<0.001). (2) Transportability by cough (CC), SI was higher than DC (68.23+/-32.1 and 33.58+/-19.04 mm; P=0.002). (3) Contact angle (CA), SI was lower than DC (10+/-3 degrees and 22+/-14 degrees ; P=0.025). (4) Rheological properties (no significant difference obtained between SI and DC). These results indicated that SI changes mucus physical properties and transportability in non-expectorators. 相似文献
4.
Lysis of pulmonary fibroblasts by lymphokine (IL-2)-activated killer cells—a mechanism affecting the human lung microenvironment?
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R ZAMBELLO L TRENTIN C ENTHAMMER A CIPRIANI C AGOSTINI G SEMENZATO 《Clinical and experimental immunology》1996,105(2):383-388
In this study we investigated whether IL-2-activated killer cells may bind and exert lytic activity against non-transformed lung fibroblasts. We demonstrated that human lymphokine-activated killer (LAK) cells generated in vitro following incubation with recombinant IL-2 of either peripheral blood mononuclear cells (PB-LAK) or lymphocytes obtained from bronchoalveolar lavage (BAL-LAK), but not resting cells, can lyse normal lung fibroblasts obtained from transbronchial lung biopsies in a 4-h 51Cr release assay. Both autologous and allogeneic fibroblasts were consistently lysed by LAK cells, thus suggesting that the phenomenon we observed is not MHC-restricted. Since fibroblasts can bind IL-2 through specific receptors, we evaluated whether long-term culture with rIL-2 could modulate the susceptibility to lysis of target cells. Our data showed that autologous fibroblasts were more resistant to lysis than allogeneic fibroblasts when they were cultured with rIL-2. Since LAK cells have been demonstrated to release a series of different immunomodulatory cytokines, we evaluated the effect of short-term incubation of fibroblasts with different factors, including IL-1, IL-2, IL-3, IL-4, IL-6, tumour necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ), on the binding and the lysis mediated by LAK cells. These cytokines were not directly cytotoxic on fibroblasts. Only IFN-γ was found to have a significant protective effect against the lysis. Our data support the concept that a self-directed cytotoxicity against pulmonary fibroblasts is generated during lymphocyte activation with rIL-2. 相似文献
5.
Functional mapping of the activity of the R region in the human T-cell leukemia virus type I long terminal repeat to increase gene expression 总被引:3,自引:0,他引:3
We previously demonstrated the activity of the R fragment in the long terminal repeat of human T-cell leukemia virus type I for elevation of the level of gene expression. In this study, the fragment was deleted with BAL31 nuclease to determine its functional domain. Series of the shortened R fragments were linked to the simian virus 40 promoter unit, which regulated expression of a reporter gene. Examination with the R fragments deleted from the 5 and 3 ends showed that borders of the functional domain were mapped within nucleotide positions 458 to 473 for the 5 end and nucleotide positions 559 to 594 for the 3 end, respectively. Thus we conclude that a 136-base-pair fragment corresponding to the second half of the R region was sufficient to allow elevation of the level of gene expression. 相似文献
6.
7.
Forty-three bronchoalveolar lavage (BAL) specimens from 40 immunocompromised patients were studied for the presence of cytomegalovirus (CMV) by rapid diagnostic methods. DNA in situ hybridization, cytology, and immunofluorescence were compared to conventional cell culture. Eleven (25%) of the 43 BAL samples grew CMV in culture. In situ hybridization detected 6 of these 11 for sensitivity, specificity, and predictive values of positive and negative of 55%, 94%, 75%, and 86%, respectively. Cytology had a sensitivity of 73% and specificity of 100%. Six Papanicolaou-stained cytospins were screened cytologically versus one hybridization cytospin, and the higher sensitivity of cytology may reflect this extensive sampling. The immunofluorescent method had a sensitivity equal to that of cytology (73%): however, the specificity (72%) was significantly less than that of either the probe or cytology. These data suggest that although in situ hybridization can be a rapid, useful method for detecting CMV in BAL specimens, cytology appears to be a more sensitive method. 相似文献
8.
Helmut Kreppel Franz -Xaver Reichl Ladislaus Szinicz Burckhard Fichtl Wolfgang Forth 《Archives of toxicology》1990,64(5):387-392
The efficacy ofdl-dimercaptopropanol (British Anti-Lewisite, BAL),dl-dimercaptopropanesulfonate (DMPS), and meso-dimercaptosuccinic acid (DMS A) was compared in reducing the acute As2O3 toxicity in mice. Mice were treated with a single equimolar dose of a dithiol compound (0.7 mmol/kg i.p.) 0.5 or 30 min after the s.c. injection of various doses of As2O3. Both DMPS and DMSA were significantly (p<0.05) more effective in mice treated 0.5 min after the poisoning if compared to BAL on an equimolar level. The highest potency ratio (PR) (LD50 with treatment/LD5o without treatment) was found in animals injected with DMSA (PR=8.6). The corresponding value for DMPS was 4.2, and for BAL 2.1, respectively. In animals treated 30 min after poisoning the efficacy of DMPS (PR = 2.6) was similar to the efficacy of DMSA 2.4, both being only slightly superior to BAL 2.O. DMPS and DMSA were found to be much less toxic than BAL. The LD50 of arsenic was 0.057 mmol/kg. The efficacy of BAL, DMPS, and DMSA in reducing the tissue content of arsenic following acute As2O3 poisoning was investigated in mice (n=6/group) and guinea pigs (n=3-4/group). The animals were injected s.c. with 0.043 mmol/kg As2O3 (containing a tracer dose of74As(III)). Thirty minutes later the antidotes were administered A were more effective in reducing the arsenic content of tissues than BAL. Moreover, BAL caused accumulation of the toxicant in the brain. It is concluded that the recommendation of BAL as drug of choice in acute arsenic poisoning needs to be carefully re-evaluated. 相似文献
9.
本文采用3-氨基邻苯二甲酰肼增强化学发光(CL)的方法检测8例特发性肺纤维化(IPE)患者和10例正常对照的肺灌洗液(BAL)全细胞的CL。IPF患者BAL细胞的自发发光显著高于对照(P<0.01),而其刺激发光竟高达对照的11倍(P<0.001),说明IPF患者肺组织的炎症细胞释放大量的反应性氧中间物(ROI),后者可能是造成肺损害的原因。此外还对5例IPF患者接受激素治疗前后BAL细胞的CL进行了比较,3例接受激素后临床明显好转,其BAL细胞的CL较治疗前显著下降(P<0.05),2例治疗后无好转的患者其BAL的CL与治疗前相比无显著性变化(P>0.05)。本文以化学发光的方法研究和探讨了特发性肺纤维化的发病机制。 相似文献
10.
支气管肺泡灌洗是用液体直接灌注,将支气管、肺泡内的分泌物、积滞物通过稀释、吸引迅速排除,起到了类似外科清创、引流排毒的作用,并以此缓解气道阻塞、改善呼吸功能、控制感染。该项技术在肺部疾病的诊断和治疗应用方面已成为主要手段之一。由于该项技术较为安全且相对无损伤,在肺科领域得到了较为广泛的应用,并日益受到临床的高度重视。该文对支气管肺泡灌洗术在小儿肺部疾病方面的临床应用研究进展进行了综述。 相似文献