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Modification
Kinds of Modification Terms modified by Modification Selected AbstractsOligodeoxynucleotide Duplexes Containing (5,S)-5,- C -Alkyl-Modified 2,-Deoxynucleosides: Can an Alkyl Zipper across the DNA Minor-Groove Enhance Duplex Stability?HELVETICA CHIMICA ACTA, Issue 11 2003Huldreich Trafelet A series of oligonucleotides containing (5,S)-5,- C -butyl- and (5,S)-5,- C -isopentyl-substituted 2,-deoxyribonucleosides were designed, prepared, and characterized with the intention to explore alkyl-zipper formation between opposing alkyl chains across the minor groove of oligonucleotide duplexes as a means to modulate DNA-duplex stability. From four possible arrangements of the alkyl groups that differ in the density of packing of the alkyl chains across the minor groove, three (duplex types I,III, Fig.,2) could experimentally be realized and their duplex-forming properties analyzed by UV-melting curves, CD spectroscopy, and isothermal titration calorimetry (ITC), as well as by molecular modeling. The results show that all arrangements of alkyl residues within the minor groove of DNA are thermally destabilizing by 1.5,3°/modification in Tm. We found that, within the proposed duplexes with more loosely packed alkyl groups (type- III duplexes), accommodation of alkyl residues without extended distorsion of the helical parameters of B-DNA is possible but does not lead to higher thermodynamic stability. The more densely packed and more unevenly distributed arrangement (type- II duplexes) seems to suffer from ecliptic positioning of opposite alkyl groups, which might account for a systematic negative contribution to stability due to steric interactions. The decreased stability in the type- III duplexes described here may be due either to missing hydrophobic interactions of the alkyl groups (not bulky enough to make close contacts), or to an overcompensation of favorable alkyl-zipper formation presumably by loss of structured H2O in the minor groove. [source] THE PREDICTIVE VALUE OF THE COCKCROFT-GAULT FORMULA AND THE MODIFICATION OF DIET IN RENAL DISEASE FORMULA FOR MORTALITY IN ELDERLY PEOPLEJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 5 2009Joris I. Rotmans MD No abstract is available for this article. [source] SHOULD WE PREVENT NON-THERAPEUTIC MUTILATION AND EXTREME BODY MODIFICATION?BIOETHICS, Issue 1 2008THOMAS SCHRAMME ABSTRACT In this paper, I discuss several arguments against non-therapeutic mutilation. Interventions into bodily integrity, which do not serve a therapeutic purpose and are not regarded as aesthetically acceptable by the majority, e.g. tongue splitting, branding and flesh stapling, are now practised, but, however, are still seen as a kind of ,aberration' that ought not to be allowed. I reject several arguments for a possible ban on these body modifications. I find the common pathologisation of body modifications, Kant's argument of duties to oneself and the objection from irrationality all wanting. In conclusion, I see no convincing support for prohibition of voluntary mutilations. [source] Redundant function of the heparan sulfate 6-O-endosulfatases Sulf1 and Sulf2 during skeletal developmentDEVELOPMENTAL DYNAMICS, Issue 2 2008Andreas Ratzka Abstract Modification of the sulfation pattern of heparan sulfate (HS) during organ development is thought to regulate binding and signal transduction of several growth factors. The secreted sulfatases, Sulf1 and Sulf2, desulfate HS on 6-O-positions extracellularly. We show that both sulfatases are expressed in overlapping patterns during embryonic skeletal development. Analysis of compound mutants of Sulf1 and Sulf2 derived from gene trap insertions and targeted null alleles revealed subtle but distinct skeletal malformations including reduced bone length, premature vertebrae ossification and fusions of sternebrae and tail vertebrae. Molecular analysis of endochondral ossification points to a function of Sulf1 and Sulf2 in delaying the differentiation of endochondral bones. Penetrance and severity of the phenotype increased with reduced numbers of functional alleles indicating redundant functions of both sulfatases. The mild skeletal phenotype of double mutants suggests a role for extracellular modification of 6-O-sulfation in fine-tuning rather than regulating the development of skeletal structures. Developmental Dynamics 237:339,353, 2008. © 2008 Wiley-Liss, Inc. [source] Peripheral arterial disease in diabetes,a reviewDIABETIC MEDICINE, Issue 1 2010E. B. Jude Diabet. Med. 27, 4,14 (2010) Abstract Diabetic patients are at high risk for peripheral arterial disease (PAD) characterized by symptoms of intermittent claudication or critical limb ischaemia. Given the inconsistencies of clinical findings in the diagnosis of PAD in the diabetic patient, measurement of ankle-brachial pressure index (ABI) has emerged as the relatively simple, non-invasive and inexpensive diagnostic tool of choice. An ABI < 0.9 is not only diagnostic of PAD even in the asymptomatic patient, but is also an independent marker of increased morbidity and mortality from cardiovascular diseases. With better understanding of the process of atherosclerosis, avenues for treatment have increased. Modification of lifestyle and effective management of the established risk factors such as smoking, dyslipidaemia, hyperglycaemia and hypertension retard the progression of the disease and reduce cardiovascular events in these patients. Newer risk factors such as insulin resistance, hyperfibrinogenaemia, hyperhomocysteinaemia and low-grade inflammation have been identified, but the advantages of modifying them in patients with PAD are yet to be proven. Therapeutic angiogenesis, on the other hand, represents a promising therapeutic adjunct in the management of PAD in these patients. Outcomes after revascularization procedures, such as percutaneous transluminal angioplasty and surgical bypasses in diabetic patients, are poorer, with increased perioperative morbidity and mortality compared with that in non-diabetic patients. Amputation rates are higher due to the distal nature of the disease. Efforts towards increasing awareness and intensive treatment of the risk factors will help to reduce morbidity and mortality in diabetic patients with PAD. [source] Interactive effect of retinopathy and macroalbuminuria on all-cause mortality, cardiovascular and renal end points in Chinese patients with Type 2 diabetes mellitusDIABETIC MEDICINE, Issue 7 2007P. C. Y. Tong Abstract Aims To examine the effect of albuminuria and retinopathy on the risk of cardiovascular and renal events, and all-cause mortality in patients with Type 2 diabetes. Methods A post-hoc analysis of 4416 Chinese patients without macrovascular complications at baseline (age 57.6 ± 13.3 years). Glomerular filtration rate (eGFR) was estimated by the abbreviated Modification of Diet in Renal Disease Study Group Formula, further adjusted for Chinese ethnicity. Clinical end points were all-cause mortality, cardiovascular events (heart failure or angina, myocardial infarction, lower limb amputation, re-vascularization procedures and stroke) and renal end points (reduction in eGFR by more than 50% or eGFR < 15 ml/min/1.73 m2 or death as a result of renal causes or need for dialysis). Results Compared with individuals without complications, subjects with retinopathy and macroalbuminuria had higher rates of cardiovascular events (14.1 vs. 2.4%), renal events (40.0 vs. 0.8%) and death (9.3 vs. 1.7%, P < 0.001). For composite event of death, cardiovascular and renal events, the presence of retinopathy, microalbuminuria alone, macroalbuminuria alone, retinopathy with microalbuminuria or retinopathy with macroalbuminuria increased the risk [hazard ratio (95% CI)] by 1.61 (1.05 to 2.47; P = 0.04), 1.93 (1.38 to 2.69; P < 0.001), 4.34 (3.02 to 6.22; P < 0.001), 2.59 [1.76 to 3.81; P < 0.001) and 6.83 (4.89 to 9.55; P < 0.001) fold, respectively. The relative excess risk as a result of interaction between retinopathy and macroalbuminuria was 15.31, implying biological interaction in the development of renal events. Conclusions In Chinese patients with Type 2 diabetes, retinopathy interacts with macroalbuminuria to increase the risk of composite cardio-renal events. [source] Demographic Factors and Their Association with Outcomes in Pediatric Submersion InjuryACADEMIC EMERGENCY MEDICINE, Issue 3 2006Lois K. Lee MD Objectives: To describe the epidemiology and outcomes of serious pediatric submersion injuries and to identify factors associated with an increased risk of death or chronic disability. Methods: A retrospective database review of 1994,2000 Massachusetts death and hospital discharge data characterized demographic factors; International Classification of Diseases, Ninth Revision (ICD-9), Clinical Modification (ICD-9-CM), or ICD-10 injury codes; and outcomes for state residents 0,19 years of age identified with unintentional submersion injuries. The authors performed logistic regression analysis to correlate outcomes with risk and demographic factors. Results: The database included 267 cases of serious submersion injury, defined as those requiring hospitalization or leading to death. Of these 267 patients, 125 (47%) drowned, 118 (44%) were discharged home, 13 (5%) were discharged home with intravenous therapy or with availability of a home health aide, and 11 (4%) were discharged to an intermediate care/chronic care facility. The authors observed a trend of improved outcome in successively younger age groups (p < 0.0001). The multivariable logistic regression analysis showed an increased likelihood of poor outcome for males compared with females (odds ratio [OR]: 2.52; 95% confidence interval [95% CI] = 1.31 to 4.84) and for African Americans compared with whites (OR: 3.47; 95% CI = 1.24 to 9.75), and a decreased likelihood of poor outcome for Hispanics compared with whites (OR: 0.056; 95% CI = 0.013 to 0.24). Conclusions: After serious pediatric submersion injuries, the overall outcome appears largely bimodal, with children primarily discharged home or dying. The observations that better outcomes occurred among younger age groups, females, and Hispanic children, with worse outcomes in African American children, suggest that injury prevention for submersion injuries should consider differences in age, gender, and race/ethnicity. [source] Origin and palaeo-environments of calcareous sediments in the Moshaweng dry valley, southeast BotswanaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2002S. Ringrose Abstract Quaternary sedimentation in the Moshaweng dry valley of southeastern Botswana is evaluated on the basis of geomorphological evolution and sedimentological analyses. Stratigraphic evidence reveals an upper surface (1095 m) containing abundant sil-calcrete, an intermediate surface (1085 m) in which sil-calcrete underlies nodular calcrete and lower (1075 m) surface in which sil-calcrete and nodular calcrete are interbedded. This subdivision is reflected in the geochemical composition of the sediments which show an overall trend of decreasing SiO2 content (and increasing CaCO3 content) with depth from the highest to the lowest surface levels. The calcretes and sil-calcretes represent modifications of pre-existing detrital Kalahari Group sand and basal Kalahari pebbles which thinned over a Karoo bedrock high. Modification took place during wet periods when abundant Ca++ -rich groundwater flowed along the structurally aligned valley system. With the onset of drier conditions, water table fluctuations led to the precipitation of nodular calcretes in the phreatic layer to a depth of about 20 m. A major geochemical change resulted in the preferential silicification of the nodular calcrete deposits. Conditions for silica mobilization may be related to drying-induced salinity and in situ geochemical differentiation brought about by pebble dissociation towards the top of the sediment pile. As calcretization and valley formation progressed to lower levels, silica release took place on a diminishing scale. Thermoluminescence dating infers a mid-Pleistocene age for sil-calcrete formation suggesting that valley evolution and original calcrete precipitation are much older. Late stage dissolution of CaCO3 from pre-existing surface calcretes or sil-calcretes led to the formation of pedogenic case-hardened deposits during a time of reduced flow through the Moshaweng system possibly during the upper or late Pleistocene. Copyright © 2002 John Wiley & Sons, Ltd. [source] Double Modification of Electrode Surface for the Selective Detection of Epinephrine and Its Application to Flow Injection Amperometric AnalysisELECTROANALYSIS, Issue 22 2009Guang-Ri Xu Abstract A glassy carbon electrode having two polymer layers has been applied to selectively detect epinephrine. The inner layer formed by electropolymerization of macrocyclic nickel complex functioned as an electrocatalyst for epinephrine oxidation and the outer layer composed of hydrolyzed polyurethane ,-benzyl L -glutamate as a screening layer. Differential pulse voltammetry showed almost 100% recovery of epinephrine even in 100-fold excess of interferents. When applied to a dual glassy carbon electrode as an amperometric detector in flow injection analysis, a linear response over 0.1,,M and 10,,M was obtained. Recovery tested for 5-fold diluted human urine samples was 97.5%. [source] Electrochemical Aptasensor for the Determination of Cocaine Incorporating Gold Nanoparticles ModificationELECTROANALYSIS, Issue 13 2008Xiaoxia Li Abstract A novel electrochemical aptasensor incorporating a signal enhancement for the determination of cocaine was designed. Gold nanoparticles were self-assembled onto the surface of a gold electrode through 1,6-hexanedithiol. A bifunctional derivative of the 32-base cocaine-binding aptamer with a redox-active ferrocene moiety and a thiol linker group at the termini of the strand was self-assembled onto the surface of gold nanoparticles. The oxidation peak current is linearly related to the concentration of cocaine from 1.0 to 15.0,,M with a detection limit of 0.5,,M. It was found that the sensitivity of the aptasensor with gold nanoparticles modification was ca. 10-fold higher than that of the aptasensor without gold nanoparticles modification. This work demonstrates that gold nanoparticles-assembled gold electrode provides a promising platform for immobilizing aptamer and enhancing the sensitivity. [source] Immobilization and Electrochemistry of Negatively Charged Proteins on Modified Nanocrystalline Metal Oxide ElectrodesELECTROANALYSIS, Issue 12 2005Emmanuel Topoglidis Abstract The immobilization of two acidic, low isoelectric point proteins, green fluorescence protein and ferredoxin (FRD) is investigated on nanocrystalline, mesoporous TiO2 and SnO2 electrodes. Modification of these electrodes with a cationic polypeptide (poly- L -lysine) or an aminosilane prior to protein immobilization is found to enhance protein binding at least ten fold, attributed to more favorable protein/electrode electrostatic interactions. Cyclic voltammetry studies of FRD-modified SnO2 electrodes indicate reversible protein electrochemistry with a midpoint potential of ,0.59,V (vs. Ag/AgCl) and an interfacial electron transfer rate constant of 0.45,s,1. [source] Diagnosis Clusters for Emergency MedicineACADEMIC EMERGENCY MEDICINE, Issue 12 2003Debbie A. Travers RN Objectives: Aggregated emergency department (ED) data are useful for research, ED operations, and public health surveillance. Diagnosis data are widely available as The International Classification of Diseases, version, 9, Clinical Modification (ICD-9-CM) codes; however, there are over 24,000 ICD-9-CM code-descriptor pairs. Standardized groupings (clusters) of ICD-9-CM codes have been developed by other disciplines, including family medicine (FM), internal medicine (IM), inpatient care (Agency for Healthcare Research and Quality [AHRQ]), and vital statistics (NCHS). The purpose of this study was to evaluate the coverage of four existing ICD-9-CM cluster systems for emergency medicine. Methods: In this descriptive study, four cluster systems were used to group ICD-9-CM final diagnosis data from a southeastern university tertiary referral center. Included were diagnoses for all ED visits in July 2000 and January 2001. In the comparative analysis, the authors determined the coverage in the four cluster systems, defined as the proportion of final diagnosis codes that were placed into clusters and the frequencies of diagnosis codes in each cluster. Results: The final sample included 7,543 visits with 19,530 diagnoses. Coverage of the ICD-9-CM codes in the ED sample was: AHRQ, 99%; NCHS, 88%; FM, 71%; IM, 68%. Seventy-six percent of the AHRQ clusters were small, defined as grouping <1% of the diagnosis codes in the sample. Conclusions: The AHRQ system provided the best coverage of ED ICD-9-CM codes. However, most of the clusters were small and not significantly different from the raw data. [source] Prevalence of epilepsy and seizures in the Navajo Nation 1998,2002EPILEPSIA, Issue 10 2009Karen Parko Summary Purpose:, To determine the prevalence of epilepsy and seizures in the Navajo. Methods:, We studied 226,496 Navajo residing in the Navajo Reservation who had at least one medical encounter between October 1, 1998 and September 30, 2002. We ascertained and confirmed cases in two phases. First, we identified patients with International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes signifying epilepsy or seizures using Indian Health Service (IHS) administrative data. Second, we reviewed medical charts of a geographic subpopulation of identified patients to confirm diagnoses and assess the positive predictive value of the ICD-9-CM codes in identifying patients with active epilepsy. Results:, Two percent of Navajo receiving IHS care were found to have an ICD-9-CM code consistent with epilepsy or seizures. Based on confirmed cases, the crude prevalence for the occurrence of any seizure (including febrile seizures and recurrent seizures that may have been provoked) in the geographic subpopulation was 13.5 per 1,000 and the crude prevalence of active epilepsy was 9.2 per 1,000. Prevalence was higher among males, children under 5 years of age, and older adults. Discussion:, The estimated prevalence of active epilepsy in the Navajo Nation is above the upper limit of the range of reported estimates from other comparable studies of U.S. communities. [source] Reprogramming of a Malonic N-Heterocyclic Carbene: A Simple Backbone Modification with Dramatic Consequences on the Ligand's Donor PropertiesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2010Vincent César Abstract Reaction of N,N, -dimesitylformamidine with dimethylmalonyl dichloride in dichloromethane in the presence of an excess of triethylamine gives the 2-chloro-4,5-dioxohexahydropyrimidine 1. The corresponding diamidocarbene 3 is generated in situ by further deprotonation with KHMDS at ,40 °C and identified by trapping with S8 to give the fully characterized (including X-ray structure) sulfur adduct 4. It also reacts with [RhCl(cod)]2 to yield the NHC complex [RhCl(3)(cod)] (5) (characterized also by X-ray structure). The donor properties of 3 were evaluated against the established IR [,(CO)] scale from [RhCl(3)(CO)2] (6). The average value of ,(CO) = 2045 cm,1 indicates that the diamidocarbene 3 is much less nucleophilic than structurally relevant six-membered NHCs including the anionic diaminocarbenes previously reported in our group. [source] Redox Modification of EMACs Through the Tuning of Ligands: Heptametal(II) Complexes of Pyrazine-Modulated Oligo-,-pyridylamido LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2009Rayyat Huseyn Ismayilov Abstract Using pyrazine-modulated oligo-,-pyridylamido ligands N2 -(pyrazin-2-yl)- N6 -[6-(pyrazin-2-ylamino)pyridin-2-yl]pyridine-2,6-diamine (H3pzpz) and N2 -(pyrazin-2-yl)- N6 -[6-(pyridin-2-ylamino)pyridin-2-yl]pyridine-2,6-diamine (H3tpz), linear heptametal(II) extended metal atom chains (EMACs) [M7(,7 -L)4X2] [L = pzpz3,, M = NiII, X = Cl, (1), NCS, (2); M = CrII, X = Cl, (3), NCS, (4); L = tpz3,, M = CrII, X = Cl, (5), NCS, (6)] were synthesized and structurally characterized. Electrochemical studies showed that heptanickel(II) complexes can undergo one reversible oxidation at +0.46 V for 1 and +0.52 V for 2. Chromium(II) species 3 exhibited two reversible, one-electron oxidation peaks at +0.61 and +0.88 V, and 5 exhibited three reversible, one-electron oxidation peaks at +0.40, +0.68 and +1.07 V. The redox peaks shifted positively when axial ligands changed from chloride to thiocyanate anions, at +0.67 and +0.92 V for 4 and +0.44, +0.73 and +1.11 V for 6. The introduction of electron-withdrawing pyrazine rings to the spacer ligand retarded oxidation of the heptametal EMACs and stabilized the complexes. In nickel(II) species 1 and 2, both terminal nickel atoms exist in spin state S = 1 whereas all the inner nickel atoms exist in spin state S = 0. Temperature-dependent magnetic research revealed an antiferromagnetic interaction between the two terminal atoms through a superexchange pathway along metal cores with a parameter of about,4 cm,1. Chromium(II) species 3,6 showed a localized structure consisting of three quadruple Cr,Cr bonds and a single terminal CrII atom. Magnetic study revealed a quintet ground state resulting from the isolated, high-spin CrII atom.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] The contribution of the intrinsic excitability of vestibular nucleus neurons to recovery from vestibular damageEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2002Cynthia L. Darlington Abstract Damage to the peripheral vestibular system results in a syndrome of ocular motor and postural abnormalities that partially and gradually abate over time in a process known as ,vestibular compensation'. The first, rapid, phase of compensation has been associated with a recovery of spontaneous resting activity in the ipsilateral vestibular nucleus complex (VNC), as a consequence of neuronal and synaptic plasticity. Increasing evidence suggests that normal VNC neurons in labyrinthine-intact animals, as well as ipsilateral VNC neurons following unilateral vestibular deafferentation (UVD), rely to some extent on intrinsic pacemaker activity provided by voltage-dependent conductances for their resting activity. Modification of this intrinsic pacemaker activity may underlie the recovery of resting activity that occurs in ipsilateral VNC neurons following UVD. This review summarizes and critically evaluates the ,intrinsic mechanism hypothesis', identifying discrepancies amongst the current evidence and suggesting experiments that may test it further. [source] Electrochemically Deposited Ca(OH)2 Coatings as a Bactericidal and Osteointegrative Modification of Ti ImplantsADVANCED ENGINEERING MATERIALS, Issue 3 2009Claus Moseke Coating of metallic implants with CaP is a common method of improving osseointegration of the device. In this study Ca(OH)2 coatings are analyzed combining the advantage of initial bacteriocidity with,after conversion of the hydroxide to hydroxyapatite in physiological media,good osteoconductivity. [source] Putative reaction mechanism of heterologously expressed octopine dehydrogenase from the great scallop, Pecten maximus (L)FEBS JOURNAL, Issue 24 2007Andre Müller cDNA for octopine dehydrogenase (ODH) from the adductor muscle of the great scallop, Pecten maximus, was cloned using 5,- and 3,-RACE. The cDNA comprises an ORF of 1197 nucleotides and the deduced amino acid sequence encodes a protein of 399 amino acids. ODH was heterologously expressed in Escherichia coli with a C-terminal penta His-tag. ODH,5His was purified to homogeneity using metal,chelate affinity chromatography and Sephadex G-100 gel filtration. Recombinant ODH had kinetic properties similar to those of wild-type ODH isolated from the scallop's adductor muscle. Site-directed mutagenesis was used to elucidate the involvement of several amino acid residues for the reaction catalyzed by ODH. Cys148, which is conserved in all opine dehydrogenases known to date, was converted to serine or alanine, showing that this residue is not intrinsically important for catalysis. His212, Arg324 and Asp329, which are also conserved in all known opine dehydrogenase sequences, were subjected to site-directed mutagenesis. Modification of these residues revealed their importance for the catalytic activity of the enzyme. Conversion of each of these residues to alanine resulted in strong increases in Km and decreases in kcat values for pyruvate and l -arginine, but had little effect on the Km and kcat values for NADH. Assuming a similar structure for ODH compared with the only available structure of a bacterial opine dehydrogenase, these three amino acids may function as a catalytic triad in ODH similar to that found in lactate dehydrogenase or malate dehydrogenase. The carboxyl group of pyruvate is then stabilized by Arg324. In addition to orienting the substrate, His212 will act as an acid,base catalyst by donating a proton to the carbonyl group of pyruvate. The acidity of this histidine is further increased by the proximity of Asp329. [source] Dynamic Magnetic Properties of Ferroic Films, Multilayers, and Patterned ElementsADVANCED FUNCTIONAL MATERIALS, Issue 15 2010Robert L. Stamps Abstract Modification and control of material properties through careful manipulation of geometry on nano- and sub-nanometer length scales is a cornerstone of modern materials science and technology. An exciting area in which these concepts have provided exceptional advances has been magnetoelectronics and nanomagnetism. Important scales in magnetic metals are conduction spin diffusion lengths and distances over which local moments correlate. Advanced techniques now allow for the creation of structures patterned on these length scales in three dimensions. The focus of this article is on magnetic structures whose dynamic properties can be strongly modified by ion bombardment and lithographic patterning. Examples are given of how microwave frequency properties can be tuned with external fields, how factors controlling magnetic switching can be controlled, and how manipulation of magnetic domain walls can be used to reveal new and surprising phenomena. [source] Immunomodulatory effects of probiotic bacteria DNA: IL-1 and IL-10 response in human peripheral blood mononuclear cellsFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2003Karen Manon Lammers Abstract A new therapeutic approach for inflammatory bowel diseases is based on the administration of probiotic bacteria. Prokaryotic DNA contains unmethylated CpG motifs which can activate immune responses, but it is unknown whether bacterial DNA is involved in the beneficial effects obtained by probiotic treatment. Peripheral blood mononuclear cells (PBMC) from healthy donors were incubated with pure DNA of eight probiotic strains and with total bacterial DNA from human feces collected before and after probiotic ingestion. Cytokine production was analyzed in culture supernatants. Modification of human microflora after probiotic administration was proven by polymerase chain reaction analysis. Here we show that Bifidobacterium genomic DNA induced secretion of the antiinflammatory interleukin-10 by PBMC. Total bacterial DNA from feces collected after probiotic administration modulated the immune response by a decrease of interleukin-1, and an increase of interleukin-10. [source] Modification of the diel vertical migration of Bythotrephes longimanus by the cold-water planktivore, Coregonus artediFRESHWATER BIOLOGY, Issue 5 2008JOELLE D. YOUNG Summary 1. The weak diel vertical migration observed in the large cladoceran Bythotrephes longimanus seems contradictory to the predator-avoidance hypothesis that predicts large zooplankton should have long migration amplitudes. However, cold-water planktivores, especially Coregonus spp., are a main source of mortality for Bythotrephes and hence a deeper migration would result in a greater overlap with these hypolimnetic planktivores. We hypothesized that Coregonus artedi (cisco) modifies the normal vertical migration pattern of Bythotrephes, such that the latter stays higher in the water column during the day and thus migrates less extremely at night. 2. The vertical distribution of Bythotrephes during the day was determined from single visits to six lakes in Ontario, Canada, all of which contain warm-water, epilimnetic planktivores but differing in whether they contain cisco. One lake of each fish type was sampled day and night every 2,3 weeks over the ice-free season to examine daytime depths and migration amplitude. 3. The vertical migration of Bythotrephes differed in the presence and absence of cisco. In the lakes with cisco, there were significantly fewer Bythotrephes in the hypolimnion and they were higher in the water column during the day. Migration amplitude was smaller in the cisco than in the non-cisco lake. These observations were not attributable to differences in physical factors, and, although not conclusively attributable to cisco, are consistent with an effect of cisco. 4. We suggest that diurnal depth selection by Bythotrephes in lakes containing cisco is a trade-off between the risk of predation by warm- versus cold-water predators, balanced by the benefits of increased temperature and feeding rates near the surface. Even in lakes without cisco, however, the vertical migration of Bythotrephes was less than expected, suggesting that diurnal depth selection is a balance between the risk from warm-water planktivores and access to sufficient light to feed effectively. [source] Fluorescent Imaging: Surface Modification of Exfoliated Layered Gadolinium Hydroxide for the Development of Multimodal Contrast Agents for MRI and Fluorescence Imaging (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 21 2009Mater. The synthesis of a new stable colloid of fluorescent LGdH layers through a newly developed surface modification method is reported by Y.-S. Yoon et al. on page 3375. This new method involves layer exfoliation, anion exchange, and PEG coating. The efficient MRI contrast-enhancement of these LGdH layers, both in vitro and in vivo, demonstrates their potential utility as a multimodal probe combining optical and MR imaging. [source] Surface Modification of Exfoliated Layered Gadolinium Hydroxide for the Development of Multimodal Contrast Agents for MRI and Fluorescence ImagingADVANCED FUNCTIONAL MATERIALS, Issue 21 2009Young-su Yoon Abstract A novel method for modifying the surface of magnetic-resonance-contrasting layered gadolinium hydroxide (LGdH) is developed providing them with water- and bio-compatibility and acid-resistance, all of which are essential for medical applications. A stable colloid of exfoliated layers is synthesized by exchanging interlayer anions of LGdH with oleate ions. The delaminated layers are successively coated with phospholipids with poly(ethylene glycol) tail groups, and their effectiveness as a contrast agent for magnetic resonance imaging (MRI) is demonstrated. The adaptability of this surface modification approach for incorporating functional molecules and fabricating a fluorescent colloid of LGdH, which has the potential utility as a multimodal probe, is also demonstrated. This result provides a novel approach for expanding the applications of layered inorganic materials and developing a new class of MRI contrast agents. [source] Influence of Dielectric Surface Chemistry on the Microstructure and Carrier Mobility of an n-Type Organic SemiconductorADVANCED FUNCTIONAL MATERIALS, Issue 15 2009Parul Dhagat Abstract This paper examines the microstructure evolution of 3,4,9,10-perylene-tetracarboxylic bis-benzimidazole (PTCBI) thin films resulting from conditions imposed during film deposition. Modification of the silicon dioxide interface with a hydrophobic monolayer (octadecyltrichlorosilane (OTS-18)) alters the PTCBI growth habit by changing the unit cell contact plane. PTCBI films deposited on oxide surface have an orientation of (011), while films atop OTS-treated oxide surface have a preferred orientation of (001). The quality of the self assembled monolayer does not appear to influence the PTCBI growth preference significantly yet it enhances the carrier mobility, suggesting that charge traps are adequately passivated due to uniform monolayer coverage. High-quality monolayers result in n-type carrier mobility values of 0.05,cm2V,1s,1 Increasing the substrate temperature during PTCBI film deposition correlates with an increase in mobility that is most significant for films deposited on OTS-treated surface. [source] Luminescent Colloidal Dispersion of Silicon Quantum Dots from Microwave Plasma Synthesis: Exploring the Photoluminescence Behavior Across the Visible SpectrumADVANCED FUNCTIONAL MATERIALS, Issue 5 2009Anoop Gupta Abstract Aiming for a more practical route to highly stable visible photoluminescence (PL) from silicon, a novel approach to produce luminescent silicon nanoparticles (Si-NPs) is developed. Single crystalline Si-NPs are synthesized by pyrolysis of silane (SiH4) in a microwave plasma reactor at very high production rates (0.1,10,g,h,1). The emission wavelength of the Si-NPs is controlled by etching them in a mixture of hydrofluoric acid and nitric acid. Emission across the entire visible spectrum is obtained by varying the etching time. It is observed that the air oxidation of the etched Si-NPs profoundly affects their optical properties, and causes their emission to blue-shift and diminish in intensity with time. Modification of the silicon surface by UV-induced hydrosilylation also causes a shift in the spectrum. The nature of the shift (red/blue) is dependent on the emission wavelength of the etched Si-NPs. In addition, the amount of shift depends on the type of organic ligand on the silicon surface and the UV exposure time. The surface modification of Si-NPs with different alkenes results in highly stable PL and allows their dispersion in a variety of organic solvents. This method of producing macroscopic quantities of Si-NPs with very high PL stability opens new avenues to applications of silicon quantum dots in optoelectronic and biological fields, and paves the way towards their commercialization. [source] Control of Charge Transport in Iridium(III) Complex-Cored Carbazole Dendrimers by Generation and Structural ModificationADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Salvatore Gambino Abstract Here, the charge transporting properties of a family of highly phosphorescent iridium(III) complex-cored carbazole dendrimers designed to have improved charge transport by incorporating carbazole units into the dendrons are studied. Firstly, the effect of the dendrimer generation and the role of dendron for materials with one dendron per ligand of the core are considered. It is shown, in contrast to previously reported light-emitting dendrimers, that in this case the carbazolyl-based dendrons have an active role in charge transport. Next, the effect on the charge transport of attaching two dendrons per ligand to the dendrimer core is explored. In this latter case, for the so called "double dendron" material a highly non-dispersive charge transport behavior is observed, together with a time-of-flight mobility of the order of 10,3,cm2 V,1,s,1. Furthermore the lowest energetic disorder parameter (,) ever reported for a solution-processed conjugated organic material is found, ,,< ,20 meV. [source] Dramatic Morphology Control in the Fabrication of Porous Polymer Films,ADVANCED FUNCTIONAL MATERIALS, Issue 22 2008Luke A. Connal Abstract Highly ordered, porous honeycomb films are prepared by the breath-figure (BF) technique using dendron-functionalized star polymers as precursors. By changing the nature of the dendritic end groups, dramatically different porous morphologies can be produced. Three series of star polymers are prepared with both the size of the 2,2-bis(methoxy)propionic acid (bis-MPA)-based dendron end group and the dendron functionality being varied. Star polymers end-functionalized with acetonide-protected dendrons (generations 1 to 4) are initially prepared and the acetonide groups subsequently deprotected to yield hydroxyl-functionalized star polymers. Modification of these hydroxyl groups with pentadecafluorooctanoyl chloride yields a third series of functionalized star polymers. The resulting star polymers have surface groups with very different polarity and by utilizing these star polymers to form honeycomb films by the BF technique, the morphology produced is dramatically different. The star polymers with amphiphilic character afford interconnected porous morphologies with multiple layers of pores. The star polymers with pentadecafluorooctanoyl end groups show highly ordered monolayers of pores with extremely thin walls and represent a new porous morphology that has previously not been reported. The ability to prepare libraries of different dendronized star polymers has given further insights into the BF technique and allows the final porous morphology to be controllably tuned utilizing the functional chain ends and generation number of the dendronized star polymers. [source] Fabrication of Reversibly Crosslinkable, 3-Dimensionally Conformal Polymeric Microstructures,ADVANCED FUNCTIONAL MATERIALS, Issue 20 2008Luke A. Connal Abstract Multifaceted porous materials were prepared through careful design of star polymer functionality and properties. Functionalized core crosslinked star (CCS) polymers with a low glass transition temperature (Tg) based on poly(methyl acrylate) were prepared having a multitude of hydroxyl groups at the chain ends. Modification of these chain ends with 9-anthracene carbonyl chloride introduces the ability to reversibly photocrosslink these systems after the star polymers were self-assembled by the breath figure technique to create porous, micro-structured films. The properties of the low Tg CCS polymer allow for the formation of porous films on non-planar substrates without cracking and photo-crosslinking allows the creation of stabilized honeycomb films while also permitting a secondary level of patterning on the film, using photo-lithographic techniques. These multifaceted porous polymer films represent a new generation of well-defined, 3D microstructures. [source] Synthesis and Optical Properties of KYF4/Yb, Er Nanocrystals, and their Surface Modification with Undoped KYF4,ADVANCED FUNCTIONAL MATERIALS, Issue 19 2008Helmut Schäfer Abstract KYF4/Yb3+, Er3+ nanocrystals with a mean diameter of approximately 13,nm were synthesized at 200,°C in the high boiling organic solvent N -(2-hydroxyethyl)ethylenediamine (HEEDA). The particles crystallize in the cubic phase known from , -NaYF4 and form transparent colloidal solutions in tetraethylene glycol (TEG) or propanol. Solutions containing 1,wt % of the nanocrystals in TEG display visible upconversion emission upon continuous wave (CW) excitation at 978,nm. Growing undoped KYF4 on the surface of the KYF4/Yb3+, Er3+ nanocrystals increases the upconversion efficiency by more than a factor of 20. The XRD data of these particles, display a slight increase in the mean particle size from 13 to 15.5,nm, indicating that only a part of the subsequently added KYF4 shell material is deposited onto the particle surface. Nevertheless the performed surface modification obviously leads to core/shell structured particles. [source] Interface Modification to Improve Hole-Injection Properties in Organic Electronic Devices,ADVANCED FUNCTIONAL MATERIALS, Issue 8 2006A. Choulis Abstract The performance of organic electronic devices is often limited by injection. In this paper, improvement of hole injection in organic electronic devices by conditioning of the interface between the hole-conducting layer (buffer layer) and the active organic semiconductor layer is demonstrated. The conditioning is performed by spin-coating poly(9,9-dioctyl-fluorene- co - N - (4-butylphenyl)-diphenylamine) (TFB) on top of the poly(3,4-ethylene dioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) buffer layer, followed by an organic solvent wash, which results in a TFB residue on the surface of the PEDOT:PSS. Changes in the hole-injection energy barriers, bulk charge-transport properties, and current,voltage characteristics observed in a representative PFO-based (PFO: poly(9,9-dioctylfluorene)) diode suggest that conditioning of PEDOT:PSS surface with TFB creates a stepped electronic profile that dramatically improves the hole-injection properties of organic electronic devices. [source] | |||||||||||||||||||||||||||||||