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21.
Abstract Plasmid pEJ4, which is a derivative of pUC19 containing an insert with 60-bp-long · homopurine homopyrimidine tract from sea urchin P. miliaris histone gene spacer, was studied by chemical probes of the DNA structure osmium tetroxide and glyoxal. The former probe reacts with pyrimidine bases, while the latter forms a stable product only with guanine residues. These probes can thus be applied as specific probes for the homopyrimidine and homopurine strands, respectively. At pH 6.0 the site-specific modification of the homopurine · homopyrimidine tract by both probes was observed at native superhelical density of the plasmid. In the linear plasmid under the same conditions this modification was absent; it appeared, however, at more acid pH values. In supercoiled DNA the hypersensitivity of the homopurine homopyrimidine tract to osmium tetroxide did not substantially change when pH was decreased from 6.0 to 4.0. Changes in NaCl concentration at pH 4.5 did not influence the hypersensitivity to osmium tetroxide; at pH 6.0 this hypersensitivity decreased with increasing NaCl concentration. These results thus show that the chemical probes recognize an unusual protonated structure containing unpaired bases or non-Watson-Crick base pairs. At pH 5.6 the site-specific modification occurred at or near to the middle of the homopurine · homopyrimidine tract, suggesting that a hairpin may be involved in the unusual structure under the given conditions. From the models suggested so far for the unusual structure of homopurine · homopyrimidine tracts our results fit best the protonated triplex H form suggest by V.I. Lyamichev, S.M. Mirkin and M.D. Frank-Kamenetskii, J. Biomol. Struct. Dyn. 3, 667 (1986). 相似文献
22.
Yee?Him Cheung Tenzin Gayden Philippe?M. Campeau Charles?A. LeDuc Donna Russo Van-Hung Nguyen Jiancheng Guo Ming Qi Yanfang Guan Steffen Albrecht Brenda Moroz Karen?W. Eldin James?T. Lu Jeremy Schwartzentruber David Malkin Albert?M. Berghuis Sherif Emil Richard?A. Gibbs David?L. Burk Megan Vanstone Brendan?H. Lee David Orchard Kym?M. Boycott Wendy?K. Chung Nada Jabado 《American journal of human genetics》2013,92(6):996-1000
Infantile myofibromatosis (IM) is the most common benign fibrous tumor of soft tissues affecting young children. By using whole-exome sequencing, RNA sequencing, and targeted sequencing, we investigated germline and tumor DNA in individuals from four distinct families with the familial form of IM and in five simplex IM cases with no previous family history of this disease. We identified a germline mutation c.1681C>T (p.Arg561Cys) in platelet-derived growth factor receptor β (PDGFRB) in all 11 affected individuals with familial IM, although none of the five individuals with nonfamilial IM had mutations in this gene. We further identified a second heterozygous mutation in PDGFRB in two myofibromas from one of the affected familial cases, indicative of a potential second hit in this gene in the tumor. PDGFR-β promotes growth of mesenchymal cells, including blood vessels and smooth muscles, which are affected in IM. Our findings indicate p.Arg561Cys substitution in PDGFR-β as a cause of the dominant form of this disease. They provide a rationale for further investigations of this specific mutation and gene to assess the benefits of targeted therapies against PDGFR-β in aggressive life-threatening familial forms of the disease. 相似文献
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Lipase from Burkholderia cepacia (lipase BC) and lipase B from Candida antarctica (CALB) show an increase of the transesterification activity in toluene (up to 2.4- and 1.7-fold, respectively), when lyophilized with 18-crown-6. Nevertheless, the increase was observed only for low (less than 100) 18-crown-6/lipase molar ratio, while at higher ratios, the activity decreased for both enzymes to values lower than those obtained in the absence of the additive. In 1,4-dioxane, the activation is lower for lipase BC (1.7-fold) and for CALB (1.5-fold). Concerning enantioselectivity, tested in the kinetic resolution of 6-methyl-5-hepten-2-ol, only in the case of CALB, an effect of the additive (the E value varied from about 120 to 280) was observed. In water, 4% (w/w) of 18-crown-6 caused a loss of activity in the hydrolysis of p-nitrophenyl laurate of about 88 and 99.75%, compared to that observed in the absence of the crown ether for CALB and lipase BC, respectively. These data and the conformational analysis of both lipases, carried out by FT/IR spectroscopy indicate that the enzyme inactivation in water and in organic solvents at 18-crown-6/lipase molar ratios, higher than 100 might be due to conformational changes caused by the additive. Instead, at molar ratios lower than 100, 18-crown-6 might increase the activity - particularly, in toluene - thanks to the fact that in its presence, the enzyme has an hydrogen bonds pattern, more similar to that in water. This suggests that the additive would be able to provide the enzyme with more water. 相似文献
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Cytoskeletal mechanics in adherent human airway smooth muscle cells: probe specificity and scaling of protein-protein dynamics 总被引:2,自引:0,他引:2
Puig-de-Morales M Millet E Fabry B Navajas D Wang N Butler JP Fredberg JJ 《American journal of physiology. Cell physiology》2004,287(3):C643-C654
We probed elastic and loss moduli in the adherent human airway smooth muscle cell through a variety of receptor systems, each serving as a different molecular window on cytoskeletal dynamics. Coated magnetic microbeads were attached to the cell surface via coating-receptor binding. A panel of bead coatings was investigated: a peptide containing the sequence RGD, vitronectin, urokinase, activating antibody against 1-integrin, nonactivating antibody against 1-integrin, blocking antibody against 1-integrin, antibody against 1-integrin, and acetylated low-density lipoprotein. An oscillatory mechanical torque was applied to the bead, and resulting lateral displacements were measured at baseline, after actin disruption by cytochalasin D, or after contractile activation by histamine. As expected, mechanical moduli depended strongly on bead type and bead coating, differing at the extremes by as much as two orders of magnitude. In every case, however, elastic and loss moduli increased with frequency f as a weak power law, f x1. Moreover, with few exceptions, data could be scaled such that elastic and frictional responses depended solely on the power law exponent x. Taken together, these data suggest that power law behavior represents a generic feature of underlying protein-protein dynamics. actin; cytoskeleton; magnetic twisting cytometry; scale free; viscoelasticity 相似文献
27.
Palecek E 《Trends in biotechnology》2004,22(2):55-58
Rapid testing of DNA and RNA nucleotide sequences is required for various research protocols including wide-scale genetic testing, diagnostics, fast detection of biological warfare agents, environmental testing and forensic medicine. At present many laboratories are interested in research and development of an inexpensive, easy-to-use, fast-response device for this purpose. Various methods based on acoustic, electronic and optical detection of the DNA hybridization event have been reported. 相似文献
28.
Tengiz I Ercan E Aliyev E Sekuri C Duman C Altuglu I 《Current Controlled Trials in Cardiovascular Medicine》2004,5(1):10
BACKGROUND: Matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of arterial aneurysms through increased proteolysis of extracellular matrix proteins. Increased proteolysis due to elevated matrix degrading enzyme activity in the arterial wall may act as a susceptibility factor for the development of coronary aneurysms. The aim of this study was to investigate the association between MMPs and presence of coronary aneurysms. METHODS: Thirty patients with aneurysmal coronary artery disease and stable angina were enrolled into study (Group 1). Fourteen coronary artery disease patients with stable angina were selected as control group (Group 2). MMP-1, MMP-3 and C-reactive protein (CRP) were measured in peripheral venous blood and matched between the groups. RESULTS: Serum MMP-3 level was higher in patients with aneurismal coronary artery disease compared to the control group (20.23 +/- 14.68 vs 11.45 +/- 6.55 ng/ml, p = 0.039). Serum MMP-1 (13.63 +/- 7.73 vs 12.15 +/- 6.27 ng/ml, p = 0.52) and CRP levels (4.78 +/- 1.47 vs 4.05 +/- 1.53 mg/l, p = 0.13) were not significantly different between the groups. CONCLUSION: MMPs can cause arterial wall destruction. MMP-3 may play role in the pathogenesis of coronary aneurysm development through increased proteolysis of extracellular matrix proteins. 相似文献
29.
Background
Laser bio-stimulation is a well-established procedure in Medical Acupuncture. Nevertheless there is still a confusion as to whether it works or the effect is just placebo. Although a plethora of scientific papers published, showing positive clinical results, there is still a lack of objective scientific proofs about the bio-stimulation effect of lasers used in Acupuncture. The objective of this work was to design and build a body surface electrode and an amplifier for biopotential recording from acupuncture points, considered here as small localized bio-sources (SLB). The design is aimed for studying SLB potentials provoked by laser stimulus, in search for objective proofs of the bio-stimulation effect of lasers used in Medical Acupuncture. 相似文献30.
Veeraswamy RK Cella M Colonna M Unanue ER 《Journal of immunology (Baltimore, Md. : 1950)》2003,170(11):5367-5372
We isolated dendritic cells (DC) from lymphoid organs of mice bearing a transgene for a membrane-bound form of the model protein hen egg white lysozyme (HEL). DC from the spleen had a lower representation of costimulatory molecules and class II MHC molecules than those isolated from lymph nodes and thymi. Splenic DC were capable of further maturation by in vivo treatment of mice with LPS. The immature DC from spleen processed HEL and displayed the chemically dominant epitope as evidenced by FACS analysis. These immature DC also presented this epitope to CD4(+) T cells. Splenic DC from another transgenic mouse (ML-5) containing serum HEL also showed the ability to process and present Ag despite low levels of circulating HEL. In vitro-derived DC from the bone marrow (bone marrow-derived DC) of mHEL mice also displayed immature to mature features and in both cases displayed HEL peptides as well as SDS-stable MHC class II molecules. Immature bone marrow-derived DC also processed exogenous HEL. We conclude that the DC sets normally found in tissue show a scale of maturation features but even the most immature process and present peptides by MHC class II molecules. 相似文献