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Resonance Analysis (resonance + analysis)
Kinds of Resonance Analysis Selected AbstractsMagnetic Resonance Analysis of Postsurgical Temporal LobectomyJOURNAL OF NEUROIMAGING, Issue 3 2001Taoufik M. Alsaadi MD ABSTRACT Background and Purpose. The effect of temporal lobe transection area, volume of postoperative gliosis, and surgical technique on patients' seizure-free outcome is unknown. The authors studied the effects of these variables on patients' seizure-free outcome. Methods. A retrospective review of magnetic resonance imaging examinations acquired 3 to 18 months after temporal lobe resection was carried out for 18 patients with intractable temporal lobe seizures and known postsurgical outcomes for more than 2 years. The total volume of radiologically probable gliosis evident on axial proton-density-weighted images was calculated for each patient using software on an independent console. The total area of temporal lobe surface transected by the scalpel was calculated as well, using sagittal T1-weighted images. The total volume of gliosis, the total area of transected temporal lobe, and the specific type of surgery (sparing vs no sparing of the superior temporal gyrus) were then correlated with the postsurgical outcome of the patients. An examiner with no prior knowledge of the patients' postsurgical outcomes carried out the above calculations and measurements. The patients' postoperative outcome was defined using Engel classifications, and patients were divided into two groups: group A with Engel class 1 (n= 9) and group B with Engel classes 2,4 (n= 9). Results. The mean volumes of postoperative gliosis were not significantly different between group A (3592.3 mm3) and group B (4270 mm3). The mean area of transected temporal lobe was also similar between group A (1865.2 mm2) and group B (1930 mm2). With regard to surgical technique, there were 5 subjects who had the superior temporal gyrus resected and 13 who did not. Eighty percent of patients with the superior temporal gyrus resected were Engel class 1 or 2, whereas only 20% were of Engel class 3 or 4. Conclusion. The authors found no clear association between postoperative outcome and residual temporal lobe gliosis, the surgical technique, or the total area of temporal lobe transected by the scalpel. [source] Water-soluble, thermoresponsive, hyperbranched copolymers based on PEG-methacrylates: Synthesis, characterization, and LCST behaviorJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2010Mario Luzon Abstract A series of water-soluble thermoresponsive hyperbranched copoly(oligoethylene glycol)s were synthesized by copolymerization of di(ethylene glycol) methacrylate (DEG-MA) and oligo(ethylene glycol) methacrylate (OEG-MA, Mw = 475 g/mol), with ethylene glycol dimethacrylate (EGD-MA) used as the crosslinker, via reversible addition fragmentation chain transfer polymerization. Polymers were characterized by size exclusion chromatography and nuclear magnetic resonance analyses. According to the monomer composition, that is, the ratio of OEG-MA: DEG-MA: EGD-MA, the lower critical solution temperature (LCST) could be tuned from 25 °C to 90 °C. The thermoresponsive properties of these hyperbranched copolymers were studied carefully and compared with their linear analogs. It was found that molecular architecture influences thermoresponsive behavior, with a decrease of around 5,10 °C in the LCST of the hyperbranched polymers compared with the LCST of linear chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2783,2792, 2010 [source] Synthesis and properties of biomimetic poly(L -glutamate)- b -poly(2-acryloyloxyethyllactoside)- b -poly(L -glutamate) triblock copolymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2004Chang-Ming Dong Abstract A novel class of biomimetic glycopolymer,polypeptide triblock copolymers [poly(L -glutamate),poly(2-acryloyloxyethyllactoside),poly(L -glutamate)] was synthesized by the sequential atom transfer radical polymerization of a protected lactose-based glycomonomer and the ring-opening polymerization of ,-benzyl- L -glutamate N -carboxyanhydride. Gel permeation chromatography and nuclear magnetic resonance analyses demonstrated that triblock copolymers with defined architectures, controlled molecular weights, and low polydispersities were successfully obtained. Fourier transform infrared spectroscopy of the triblock copolymers revealed that the ,-helix/,-sheet ratio increased with the poly(benzyl- L -glutamate) block length. Furthermore, the water-soluble triblock copolymers self-assembled into lactose-installed polymeric aggregates; this was investigated with the hydrophobic dye solubilization method and ultraviolet,visible analysis. Notably, this kind of aggregate may be useful as an artificial polyvalent ligand in the investigation of carbohydrate,protein recognition and for the design of site-specific drug-delivery systems. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5754,5765, 2004 [source] EthR, a repressor of the TetR/CamR family implicated in ethionamide resistance in mycobacteria, octamerizes cooperatively on its operatorMOLECULAR MICROBIOLOGY, Issue 1 2004Jean Engohang-Ndong Summary Ethionamide (ETH) is an important second-line antitubercular drug used for the treatment of patients infected with multidrug-resistant Mycobacterium tuberculosis. Although ETH is a structural analogue of isoniazid, only little cross-resistance to these two drugs is observed among clinical isolates. Both isoniazid and ETH are pro-drugs that need to be activated by mycobacterial enzymes to exert their antimicrobial activity. We have recently identified two M. tuberculosis genes, Rv3854c (ethA) and Rv3855 (ethR), involved in resistance to ETH. ethA encodes a protein that belongs to the Flavin-containing monooxygenase family catalysing the activation of ETH. We show here that ethR, which encodes a repressor belonging to the TetR/CamR family of transcriptional regulators, negatively regulates the expression of ethA. By the insertion of the ethA promoter region upstream of the lacZ reporter gene, overexpression of ethR in trans was found to cause a strong inhibition of ethA expression, independently of the presence of ETH in the culture media. Electrophoretic mobility shift assays indicated that EthR interacts directly with the ethA promoter region. This interaction was confirmed by DNA footprinting analysis, which, in addition, identified the EthR-binding region. Unlike other TetR/CamR members, which typically bind 15 bp operators, EthR recognises an unusually long 55 bp region suggesting multimerization of the repressor on its operator. Identification by primer-extension of the ethA transcriptional start site indicated that it is located within the EthR-binding region. Taken together, bacterial two-hybrid experiments and gel filtration assays suggested a dimerization of EthR in the absence of its operator. In contrast, surface plasmon resonance analyses showed that eight EthR molecules bind cooperatively to the 55 bp operator, which represents a novel repression mechanism for a TetR/CamR member. [source] Characterization of a novel NCAM ligand with a stimulatory effect on neurite outgrowth identified by screening a combinatorial peptide libraryEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2002Lars C. B. Rønn Abstract The neural cell adhesion molecule, NCAM, plays a key role in neural development and plasticity mediating cell adhesion and signal transduction. By screening a combinatorial library of synthetic peptides with NCAM purified from postnatal day 10 rat brains, we identified a nonapeptide, termed NCAM binding peptide 10 (NBP10) and showed by nuclear magnetic resonance analysis that it bound the NCAM IgI module of NCAM. NBP10 modulated cell aggregation as well as neurite outgrowth induced specifically by homophilic NCAM binding. Moreover, both monomeric and multimeric forms of NBP10 stimulated neurite outgrowth from primary hippocampal neurons. The neurite outgrowth response to NBP10 was inhibited by a number of compounds previously shown to inhibit neurite outgrowth induced by homophilic NCAM binding, including voltage-dependent calcium channel antagonists, suggesting that NBP10 induced neurite outgrowth by activating a signal transduction pathway similar to that activated by NCAM itself. Moreover, an inhibitor of intracellular calcium mobilization, TMB-8, prevented NBP10-induced neurite outgrowth suggesting that NCAM-dependent neurite outgrowth also requires mobilization of calcium from intracellular calcium stores in addition to calcium influx from extracellular sources. By single-cell calcium imaging we further demonstrated that NBP10 was capable of inducing an increase in intracellular calcium in PC12E2 cells. Thus, the NBP10 peptide is a new tool for the study of molecular mechanisms underlying NCAM-dependent signal transduction and neurite outgrowth, and could prove to be a useful modulator of regenerative processes in the peripheral and central nervous system. [source] Preferential phosphorus leaching from an irrigated grassland soilEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2005G. S. Toor Summary Intact lysimeters (50 cm diameter, 70 cm deep) of silt loam soil under permanent grassland were used to investigate preferential transport of phosphorus (P) by leaching immediately after application of dairy effluent. Four treatments that received mineral P fertilizer alone (superphosphate at 45 kg P ha,1 year,1) or in combination with effluent (at , 40,80 kg P ha,1 year,1) over 2 years were monitored. Losses of total P from the combined P fertilizer and effluent treatments were 1.6,2.3 kg ha,1 (60% of overall loss) during eight drainage events following effluent application. The rest of the P lost (40% of overall loss) occurred during 43 drainage events following a significant rainfall or irrigation compared with 0.30 kg ha,1 from mineral P fertilizer alone. Reactive forms of P (mainly dissolved reactive P: 38,76%) were the dominant fractions in effluent compared with unreactive P forms (mainly particulate unreactive P: 15,56%). In contrast, in leachate following effluent application, particulate unreactive P was the major fraction (71,79%) compared with dissolved reactive P (1,7%). The results were corroborated by 31P nuclear magnetic resonance analysis, which showed that inorganic orthophosphate was the predominant P fraction present in the effluent (86%), while orthophosphate monoesters and diesters together comprised up to 88% of P in leachate. This shows that unreactive P forms were selectively transported through soil because of their greater mobility as monoesters (labile monoester P and inositol hexakisphosphate) and diesters. The short-term strategies for reducing loss of P after application of dairy effluent application should involve increasing the residence time of applied effluent in the soil profile. This can be achieved by applying effluent frequently in small amounts. [source] The stress response protein Gls24 is induced by copper and interacts with the CopZ copper chaperone of Enterococcus hiraeFEMS MICROBIOLOGY LETTERS, Issue 1 2010Jivko V. Stoyanov Abstract Intracellular copper routing in Enterococcus hirae is accomplished by the CopZ copper chaperone. Under copper stress, CopZ donates Cu+ to the CopY repressor, thereby releasing its bound zinc and abolishing repressor,DNA interaction. This in turn induces the expression of the cop operon, which encodes CopY and CopZ, in addition to two copper ATPases, CopA and CopB. To gain further insight into the function of CopZ, the yeast two-hybrid system was used to screen for proteins interacting with the copper chaperone. This led to the identification of Gls24, a member of a family of stress response proteins. Gls24 is part of an operon containing eight genes. The operon was induced by a range of stress conditions, but most notably by copper. Gls24 was overexpressed and purified, and was shown by surface plasmon resonance analysis to also interact with CopZ in vitro. Circular dichroism measurements revealed that Gls24 is partially unstructured. The current findings establish a novel link between Gls24 and copper homeostasis. [source] Shed HER2 extracellular domain in HER2-mediated tumor growth and in trastuzumab susceptibility,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2010Gaia C. Ghedini The question of the serum HER2 extracellular domain (HER2/ECD) measurement for prediction of response to the anti-HER2 antibody Trastuzumab is still an open and current matter of clinical debate. To elucidate the involvement of shed HER2/ECD in HER2-driven tumor progression and in guiding therapy of individual patients, we examined biological effects exerted by elevated HER2/ECD in cancer growth and in response to Trastuzumab. To this purpose SKOV3 tumor cells were stably transfected to release a recombinant HER2/ECD molecule (rECD). Transfectants releasing high levels of 110-kDa rECD, identical in size to native HER2/ECD (nECD), grew significantly slower than did controls, which constitutively released only basal levels of nECD. While transmembrane HER2 and HER1 were expressed at equal levels by both controls and transfected cells, activation of these molecules and of downstream ERK2 and Akt was significantly reduced only in rECD transfectants. Surface plasmon resonance analysis revealed heterodimerization of the rECD with HER1, -2, and -3. In cell growth bioassays in vitro, shed HER2 significantly blocked HER2-driven tumor cell proliferation. In mice, high levels of circulating rECD significantly impaired HER2-driven SKOV3 tumor growth but not that of HER2-negative tumor cells. In vitro and in mice, Trastuzumab significantly inhibited tumor growth due to the rECD-facilitated accumulation of the antibody on tumor cells. Globally our findings sustain the biological relevance of elevated HER2/ECD levels in the outcome of HER2-disease and in the susceptibility to Trastuzumab-based therapy. J. Cell. Physiol. 225: 256,265, 2010. © 2010 Wiley-Liss, Inc. [source] Effect of Guava (Psidium guajava L.) Leaf Extract on Glucose Uptake in Rat HepatocytesJOURNAL OF FOOD SCIENCE, Issue 5 2009Fang-Chi Cheng ABSTRACT:, People in oriental countries, including Japan and Taiwan, boil guava leaves (Psidium guajava L.) in water and drink the extract as a folk medicine for diabetes. The present study investigated the enhancement of aqueous guava leaf extract on glucose uptake in rat clone 9 hepatocytes and searched for the active compound. The extract was eluted with MeOH-H2O solutions through Diaion, Sephadex, and MCI-gel columns to separate into fractions with different polarities. The uptake test of 2-[1- 14C] deoxy-D-glucose in rat clone 9 hepatocytes was performed to evaluate the hypoglycemic effect of these fractions. The active compound was identified by nuclear magnetic resonance analysis and high-performance liquid chromatography (HPLC). The results revealed that phenolics are the principal component of the extract, that high polarity fractions of the guava leaf extract are enhancers to glucose uptake in rat clone 9 hepatocytes, and that quercetin is the major active compound. We suggest that quercetin in the aqueous extract of guava leaves promotes glucose uptake in liver cells, and contributes to the alleviation of hypoglycemia in diabetes as a consequence. [source] A simple method to discriminate between ,2 -glycoprotein I- and prothrombin-dependent lupus anticoagulantsJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 4 2003M. J. A. Simmelink Summary., Lupus anticoagulants (LAC) are a heterogeneous group of autoantibodies that prolong phospholipid-dependent clotting assays. The autoantibodies that cause LAC activity are predominantly directed against ,2 -glycoprotein I (,2GPI) or prothrombin. In the present study, we describe a method to differentiate between LAC caused by antibodies directed against ,2GPI or prothrombin. Monoclonal antibodies, affinity purified patient antibodies, and selected patient samples were used to show that in an aPTT-based clotting assay (PTT-LA; Diagnostica Stago), the use of cardiolipin vesicles in the neutralization procedure discriminates between ,2GPI- or prothrombin-dependent LAC activities. Addition of cardiolipin vesicles shortened the prolonged clotting time caused by anti-,2GPI antibodies with LAC activity, whereas this procedure further prolonged clotting times caused by antiprothrombin antibodies with LAC activity. In contrast, addition of phosphatidylcholine/phosphatidylserine vesicles corrected prolonged clotting times caused by either anti-,2GPI or antiprothrombin antibodies with LAC activity. The effects of cardiolipin (CL) on ,2GPI-induced LAC activity were specific for contact activation mediated clotting assays. Possible explanations for these findings are the relatively high affinity of ,2GPI for cardiolipin, as determined by surface plasmon resonance analysis, and inhibition by anti-,2GPI antibodies of the CL-induced prolongation of the PTT-LA. [source] Multinuclear magnetic resonance analysis of 2-(trifluoromethyl)-2-oxazolineMAGNETIC RESONANCE IN CHEMISTRY, Issue 10 2005Anthony Foris Abstract 1H, 19F, 13C, 15N, and 17O NMR chemical shifts and 1H- 1H, 1H- 19F, 1H- 13C, 19F- 13C, and 19F- 15N coupling constants are reported for 2-(trifluoromethyl)-2-oxazoline. Copyright © 2005 John Wiley & Sons, Ltd. [source] Surface Plasmon-coupled Polarized Emission of N-Acetyl- l -Trytophanamide,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2004Ignacy Gryczynski We report an observation of ultraviolet (UV) surface plasmon-coupled emission (SPCE) of N-acetyl- l -tryptophanamide (NATA). The sample was spin coated from poly(vinyl alcohol) (PVA) solution on 20 nmaluminium film deposited on a quartz substracte. The directional UV SPCE occurs within a well-defined narrow angle at 52dG from the normal to the coupling hemicylinder quartz prism. The NATA directional emission is highly p polarized as expected for surface plasmon-coupled radiation. The 10 nm protective SiO2 layer deposited on top of the aluminum film significantly neutralized the fluorophore quenching by the metal surface. SPCE of NATA demonstratees a remarkable intrinsic dispersive property,the maximum of the emission spectrum depends on the observation angle. The efficient spectral resolution of SPCE can be used in the construction of miniaturized spectrofluorometers. The observation of SPCE of tryptophan opens a new possibility for the study of many unlabeled proteins with the technique complementary to surface plasmon resonance analysis. [source] Crystal structures of the Arabidopsis thaliana proliferating cell nuclear antigen 1 and 2 proteins complexed with the human p21 C-terminal segmentPROTEIN SCIENCE, Issue 5 2009Wojciech Strzalka Abstract The proliferating cell nuclear antigen (PCNA) is well recognized as one of the essential cellular components of the DNA replication machinery in all eukaryotic organisms. Despite their prominent importance, very little biochemical and structural information about plant PCNAs is available, in comparison with that obtained from other eukaryotic organisms. We have determined the atomic resolution crystal structures of the two distinct Arabidopsis thaliana PCNAs (AtPCNA), both complexed with the C-terminal segment of human p21. Both AtPCNAs form homotrimeric ring structures, which are essentially identical to each other, including the major contacts with the p21 peptide. The structure of the amino-terminal half of the p21 peptide, containing the typical PIP box sequence, is remarkably similar to those observed in the previously reported crystal structures of the human and archaeal PCNA-PIP box complexes. Meanwhile, the carboxy-terminal halves of the p21 peptide in the plant PCNA complexes are bound to the protein in a unique manner, most probably because of crystal packing effects. A surface plasmon resonance analysis revealed high affinity between each AtPCNA and the C-terminal fragment of human p21. This result strongly suggests that the interaction is functionally significant, although no plant homologs of p21 have been identified yet. We also discovered that AtPCNA1 and AtPCNA2 form heterotrimers, implying that hetero-PCNA rings may play critical roles in cellular signal transduction, particularly in DNA repair. [source] Sterol Composition of Pneumocystis jirovecii with Blocked 14,-Demethylase ActivityTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2004JOSÉ-LUIS GINER ABSTRACT Several drugs that interact with membrane sterols or inhibit their syntheses are effective in clearing a number of fungal infections. The AIDS-associated lung infection caused by Pneumocystis jirovecii is not cleared by many of these therapies. Pneumocystis normally synthesizes distinct C28 and C29 24-alkylsterols, but ergosterol, the major fungal sterol, is not among them. Two distinct sterol compositional phenotypes were previously observed in P. jirovecii. One was characterized by ,7 C28 and C29 24-alkylsterols with only low proportions of higher molecular mass components. In contrast, the other type was dominated by high C31 and C32 24-alkylsterols, especially pneumocysterol. In the present study, 28 molecular species were elucidated by nuclear magnetic resonance analysis of a human lung specimen containing P. jirovecii representing the latter sterol profile phenotype. Fifteen of the 28 had the methyl group at C-14 of the sterol nucleus and these represented 96% of the total sterol mass in the specimen (excluding cholesterol). These results strongly suggest that sterol 14,-demethylase was blocked in these organisms. Twenty-four of the 28 were 24-alkylsterols, indicating that methylation of the C-24 position of the sterol side chain by S-adenosyl-L-methionine:sterol C-24 methyl transferase was fully functional. [source] Vibration Analysis on Incubating Eggs and Its Relation to Embryonic DevelopmentBIOTECHNOLOGY PROGRESS, Issue 3 2003Bart J. Kemps Coucke (1998) was the first to use acoustic resonance analysis to monitor embryo development in chicken eggs. He remarked that at around 100 hours of incubation, the course of the resonant frequency and damping changed abruptly in the case of fertile eggs. He also showed that these changes were related to a physiologic event during early embryonic development. The objective of our study is to monitor the course of the vibration parameters during the early incubation of chicken eggs and to relate these changes to egg and embryo characteristics. A total of 72 Hybro eggs were incubated vertically in a small incubator at standard conditions. Several egg parameters were measured before incubation. During the early stages of incubation the vibration behavior of these eggs was monitored. The time at which the damping of the vibration suddenly changed, the diameter of the eggs and their interaction were found to be significant explanatory variables in order to predict hatching time. A correlation coefficient r of 0.72 was obtained. [source] Structural and Biophysical Characterization of XIAP BIR3 G306E Mutant: Insights in Protein Dynamics and Application for Fragment-Based Drug DesignCHEMICAL BIOLOGY & DRUG DESIGN, Issue 3 2009Cathy D. Moore Previous reports describe modulators of X-linked inhibitor of apoptosis (XIAP),caspase interaction designed from the AVPI N-terminal peptide sequence of second mitochondria-derived activator of caspase. A fragment-based drug design strategy was initiated to identify therapeutic non-peptidomimetic antagonists of X-linked inhibitor of apoptosis protein,protein interactions. Fragments that bind to the AVPI binding site of BIR3 (bacculoviral inhibitory repeat) were identified, and to further localize the fragment binding within the AVPI binding site, a point mutation was designed which alters the dynamics of flexible loops and blocks PI region of the binding cleft, thus enabling definition of weakly bound small molecules in the AV portion of the binding cleft. Nuclear magnetic resonance analysis confirmed the G306E mutation stabilizes the AV pocket. Biophysical characterization of the mutant confirms conformation change within the PI sub-pocket as evidenced by a significant diminishment in binding affinity of AVPI mimetics, yet the binding affinity of the smaller AV mimetics is maintained or slightly improved in the mutant compared with wild-type. Additional data from non-covalent mass spectrometry analysis shows enhanced binding of AV mimetics to the G306E mutant over the wild-type. The presented data outline a protein engineering strategy that allowed mapping of AV-replacements with better sensitivity and precision. [source] Templated assembly of the pH-sensitive membrane-lytic peptide GALACHEMICAL BIOLOGY & DRUG DESIGN, Issue 6 2004D.H. Haas Abstract:, Delivery of protein or nucleic acid therapeutics into intracellular compartments may require facilitation to allow these macromolecules to cross otherwise impermeant cellular membranes. Peptides capable of forming membrane-spanning channels hold promise as just such facilitators, although the requirement for peptide oligomerization to form these channels may limit their effectiveness. Synthetic molecules containing multiple copies of membrane-active peptides attached to a template molecule in a pre-oligomerized form have attracted interest for drug-delivery applications. Using three template designs, we synthesized multimeric versions of the pH-sensitive lytic peptide GALA and compared their performance to monomeric GALA. Template assembly stabilized helix formation: templated GALA retained , -helical structure even at neutral pH, unlike monomeric GALA. In membrane leakage assays, templated GALA retained the pH sensitivity of the monomer, with improved leakage for dimeric GALA. Surprisingly, trimeric GALA was less effective, particularly when synthesized with a larger and more flexible spacer. Surface plasmon resonance analysis indicated that reversible binding of templated GALA to lipid surfaces at acidic conditions was greatly reduced compared with monomeric GALA, but that the amount of irreversibly bound material was similar. We interpreted these results to indicate that templated peptides may cyclize into ,self-satisfied' oligomeric structures, incapable of further aggregation and subsequent pore formation. Future design of templated peptides must be carefully performed to avoid this unwanted consequence. [source] | ||||||||||||||||