bluuebunny/crossref_metadata_2025 huggingface dataset:
Peroxide detoxification by brain cells
Authors: Dringen Ralf , Pawlowski Petra G. , Hirrlinger Johannes
Published: November 2004

Peroxides are generated continuously in cells that consume oxygen. Among the different peroxides, hydrogen peroxide is the molecule that is formed in highest quantities. In addition, organic hydroperoxides are synthesized as products of cellular metabolism. Generation and disposal of peroxides is a very important process in the human brain, because cells of this organ consume 20% of the oxygen used by the body. To prevent cellular accumulation of peroxides and damage generated by peroxide‐derived radicals, brain cells contain efficient antioxidative defense mechanisms that dispose of peroxides and protect against oxidative damage. Cultured brain cells have been used frequently to investigate peroxide metabolism of neural cells. Efficient disposal of exogenous hydrogen peroxide was found for cultured astrocytes, oligodendrocytes, microglial cells, and neurons. Comparison of specific peroxide clearance rates revealed that cultured oligodendrocytes dispose of the peroxide quicker than the other neural cell cultures. Both catalase and the glutathione system contribute to the clearance of hydrogen peroxide by brain cells. For efficient glutathione‐dependent reduction of peroxides, neural cells contain glutathione in high concentration and have substantial activity of glutathione peroxidase, glutathione reductase, and enzymes that supply the NADPH required for the glutathione reductase reaction. This article gives an overview on the mechanisms involved in peroxide detoxification in brain cells and on the capacity of the different types of neural cells to dispose of peroxides. © 2004 Wiley‐Liss, Inc.
Mitochondrial permeability transition in CNS trauma: Cause or effect of neuronal cell death?
Authors: Sullivan P.G. , Rabchevsky A.G. , Waldmeier P.C. , Springer J.E.
Published: November 2004

Experimental traumatic brain injury (TBI) and spinal cord injury (SCI) result in a rapid and significant necrosis of neuronal tissue at the site of injury. In the ensuing hours and days, secondary injury exacerbates the primary damage, resulting in significant neurologic dysfunction. It is believed that alterations in excitatory amino acids (EAA), increased reactive oxygen species (ROS), and the disruption of Ca2+ homeostasis are major factors contributing to the ensuing neuropathology. Mitochondria serve as the powerhouse of the cell by maintaining ratios of ATP:ADP that thermodynamically favor the hydrolysis of ATP to ADP + Pi, yet a byproduct of this process is the generation of ROS. Proton‐pumping by components of the electron transport system (ETS) generates a membrane potential (ΔΨ) that can then be used to phosphorylate ADP or sequester Ca2+ out of the cytosol into the mitochondrial matrix. This allows mitochondria to act as cellular Ca2+ sinks and to be in phase with changes in cytosolic Ca2+ levels. Under extreme loads of Ca2+, however, opening of the mitochondrial permeability transition pore (mPTP) results in the extrusion of mitochondrial Ca2+ and other high‐ and low‐molecular weight components. This catastrophic event discharges ΔΨ and uncouples the ETS from ATP production. Cyclosporin A (CsA), a potent immunosuppressive drug, inhibits mitochondrial permeability transition (mPT) by binding to matrix cyclophilin D and blocking its binding to the adenine nucleotide translocator. Peripherally administered CsA attenuates mitochondrial dysfunction and neuronal damage in an experimental rodent model of TBI, in a dose‐dependent manner. The underlying mechanism of neuroprotection afforded by CsA is most likely via interaction with the mPTP because the immunosuppressant FK506, which has no effect on the mPT, was not neuroprotective. When CsA was administrated after experimental SCI at the same dosage and regimen used TBI paradigms, however, it had no beneficial neuroprotective effects. This review takes a comprehensive and critical look at the evidence supporting the role for mPT in central nervous system (CNS) trauma and highlights the differential responses of CNS mitochondria to mPT induction and the implications this has for therapeutically targeting the mPT in TBI and SCI. © 2004 Wiley‐Liss, Inc.
Molecular and cellular mechanisms of neuroprotection by vascular endothelial growth factor
Authors: Sun Feng‐Yan , Guo Xin
Published: November 2004

The present view of the neuroprotective functions and mechanisms of action of vascular endothelial growth factor (VEGF) is based on studies of neuronal ischemic/hypoxic models in vivo and in vitro. Endogenous neuronal VEGF increases in the ischemic brain and plays a neuroprotective role in the pathophysiologic processes that follow stroke. Exogenous VEGF, directly administered or overexpressed by gene delivery into rat brains, reduces ischemic brain infarct and decreases hypoxic neuronal death. The main neuroprotective mechanisms of VEGF include: (1) modulation of the phosphatidylinositol 3′‐kinase (PI3K)/Akt/nuclear factor‐κB signaling pathway, inhibition of caspase‐3 activity, and reduction of ischemic neuronal apoptosis; (2) inhibition of outward delayed rectifier potassium channel currents and increase of ischemia‐induced tyrosine phosphorylation of Kv1.2 potassium channel proteins via activation of the PI3K pathway; and (3) enhancement of proliferation and migration of neural progenitors in the subventricular zone and improvement of striatal neurogenesis and maturation of newborn neurons in adult rat brains after stroke. © 2004 Wiley‐Liss, Inc.
Developing metropolitan tourism on the fringe of central London
Authors: Maitland Robert , Newman Peter
Published: November 2004

The paper examines the growth of a ‘new tourism area’ in Islington, north London — a locality that lacks a large attraction, acknowledged distinctive heritage and has not been planned as a destination. We review supply side changes and link them to the recent literature on economic and spatial trends in cities, particularly the role of amenity. We report on a survey of Islington visitors that shows they are drawn by distinctive qualities of place rather than particular attractions. The visitors have characteristics that distinguish them from visitors to London as a whole, but we speculate that they have similarities to Islington workers and residents in their search for amenity, entertainment and high‐level consumption services. In the final section of the paper we explore the consequences of our findings for understanding the growth of urban tourism. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and Characterization of a Highly Soluble Poly[3‐(10‐hydroxydecyl)thiophene]
Authors: Paganin Luisa , Lanzi Massimiliano , Costa‐Bizzarri Paolo , Bertinelli Franco , Masi Corrado
Published: November 2004

The preparation of a regioregular HH‐TT linked poly[3‐(10‐hexanoyloxy)decyl]thiophene and its conversion to the corresponding hydroxy‐functionalized polymer is described and discussed. The hydroxydecyl polymer, highly soluble in common organic solvents, has been characterized via NMR, FT‐IR, DSC and X‐ray diffractometry.
New Copoly(bisphenol‐A)carbonates, Having Hydrophilic Porphyrin Units as End‐Groups, Synthesized by Melt‐Reacting Processes
Authors: Scamporrino Emilio , Alicata Rossana , Bazzano Sebastiano , Vitalini Daniele , Mineo Placido
Published: November 2004

The synthesis of some poly(bisphenol‐A)carbonates (PCs) containing hydrophilic porphyrin units as end groups, by thermal treatment of commercial PC and 5,10,15‐tri{p[ω‐methoxy‐poly(oxyethylene)]phenyl}20(p‐hydroxy phenyl)porphyrin (I) blends, is reported. A suitable choice of reaction temperature, molar composition and reaction time, allowing the extent of the outer‐inner transesterification reactions, leads to a gradual insertion of porphyrin units in the polymer chains. The composition of the obtained materials was inferred by GPC and MALDI‐TOF mass spectrometric analysis.
Propene‐Norbornene Copolymers: Synthesis and Microstructure
Authors: Boggioni L. , Tritto I. , Ragazzi M. , Carbone P. , Ferro D.R.
Published: November 2004

Series of propene(norbornene (P–N) copolymers were synthesized in the presence of two C2 symmetric zirconocenes, rac‐Et(Indenyl)2ZrCl2 (1) and rac‐Me2Si(Indenyl)2ZrCl2 (2), and of the Cs symmetric zirconocene Me2C(Cp)(Fluorenyl)ZrCl2 (3) with MAO as cocatalyst. P–N copolymers were characterized by 13C NMR spectroscopy, SEC, and DSC. A first assignment of the main 13C NMR signals of P–N copolymers obtained with 1 and 2 containing isolated N units was obtained on the basis of DEPT experiments and by comparison with isotactic polypropene (i‐PP) and E–N copolymer spectra. Ab initio theoretical 13C NMR chemical shifts, combined with R.I.S. statistics of the P–N chain, gave important detailed indications for the assignment of the complex 13C spectra of these copolymers. Such assignments were used to estimate the N copolymer content. The comparison of N content values obtained from the areas of different regions of the spectra reveals that 1,3 propene misinsertions are formed in greater amount as the [N]/[P] ratio of the feed increases. This may be due to the steric hindrance of the Mt–tertiary carbon bond when N is the last inserted unit, which makes difficult the next propene insertion and causes the low polymerization activities, molecular masses and Tg. The spectra of P–N copolymers obtained with 3 revealed to be even more complex. A limited assignment of the spectrum has been achieved. This allowed us to evaluate the N content in the copolymers and to evidence the low tendency of the Cs symmetric 3 to give 1,3 propene misinsertions in P–N copolymers. This is in agreement with the results observed with this catalyst in propene homopolymerization.
Recent Advances in MALDI Mass Spectrometry of Polymers
Authors: Montaudo Giorgio , Carroccio Sabrina , Montaudo Maurizio S. , Puglisi Concetto , Samperi Filippo
Published: November 2004

Matrix‐Assisted Laser Desorption/Ionization (MALDI) allows the identification of repeat units and end groups, the structural analysis of linear and cyclic oligomers, and the estimate of composition and sequence for copolymers. MALDI has also been applied to the measurement of molar mass distributions in polymers and to the study of thermal and oxidative processes in polymers. This paper illustrates the detection of self‐association in macromolecules made by coupling MALDI and Size Exclusion Chromatography (SEC), the investigation of polymer oxidation phenomena, and the characterization of copolymers formed in the processing of reactive polymer blends.
Functionalization of Styrene‐Olefin Block Copolymers by Melt Radical Grafting of Glycidyl Methacrylate and Reactive Blending with PET
Authors: Pracella Mariano , Chionna Donatella
Published: November 2004

Blocks copolymers styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene (SEBS) and styrene‐b‐(ethylene‐co‐propylene) (SEP, SEPSEP), with different styrene content and number of blocks in the chain, were functionalized with glycidyl methacrylate (GMA) by melt radical grafting. The influence of monomer concentration, radical initiator and copolymer structure on the grafting degree was examined. The grafted copolymers were characterised by DSC and capillary rheometry. Blends of PET with functionalized SEBS and SEPSEP showed a marked improvement of phase morphology and elongation at break when compared to blends with unfunctionalized copolymers.
Physical‐Mechanical and Thermal Properties of Polyethylene Toughened with Submicron BaSO4 Particles
Authors: Bianchi Francesca , Lazzeri Andrea , Pracella Mariano , D'Aquino Arianna , Ligeri Giorgio
Published: November 2004

The mechanical and thermal behaviour and the morphology of High‐Density Polyethylene (HDPE), filled with different types of Barium Sulfate (BaSO4) submicron particles have been examined. Composites with a filler content in the range 5‐15 vol% were obtained with a twin screw mixer‐single screw extruder and then analyzed by means of DSC, SEM and tensile and Charpy impact tests. The effect of different surface treatments of filler particles on the composite properties has been studied. The results indicate that the addition of BaSO4 particles leads to slight increase in Young's modulus and to a decrease in the yield stress independently of surface treatment. The fracture resistance tests demonstrated a strong influence of filler content and surface agents on impact parameters. The use of BaSO4 filler appears to induce a good toughening of HDPE, especially at low volume content, while surface agents reduce particle agglomeration and decrease the adhesion between filler and polymer matrix.
Properties/Structure Relationships in Innovative PCL‐SiO2 Nanocomposites
Authors: Avella Maurizio , Bondioli Federica , Cannello Valeria , Cosco Simona , Errico Maria Emanuela , Ferrari Anna Maria , Focher Bonaventura , Malinconico Mario
Published: November 2004

Poly(caprolactone) (PCL) based nanocomposites filled with silica (SiO2) nanoparticles were prepared and the relationships between their structure and properties were investigated.

Silica nanoparticles were synthesized by Stöber method. Surface of silica nanoparticles were successively functionalized in order to promote matrix/filler compatibilization and to improve interfacial adhesion. Morphological analysis performed on the fractured surface of samples revealed that the compatibilization process permitted to obtain an homogeneous and discrete distribution of the nanoparticles into polymeric matrix. Mechanical test showed that in the presence of a strong interphase, the elastic modulus increases of about 25% than the neat polymeric matrix value. Preliminary modelling analysis was also performed in order to assess the correlation existing between a computational model and experimental data.
Polyimide‐Silica Hybrids: Spectroscopy, Morphology and Mechanical Properties
Authors: Abbate Mario , Musto Pellegrino , Ragosta Giuseppe , Scarinzi Gennaro , Mascia Leno
Published: November 2004

Polyimide/silica hybrids were prepared by a sol‐gel process and were evaluated in terms of curing behaviour, morphology and mechanical properties. The spectroscopic examination showed that the presence of the inorganic phase accelerates the imidization of the polyamic acid. Two types of morphology for the silica phase were obtained by tailoring the composition of the precursor solution mixture. The mechanical properties were found to be strongly dependent on the system morphology. The largest increase in rigidity and strength properties were achieved when the two phases were co‐continuous.
Organic‐Inorganic Hybrid Materials with the Ability to Bind Metal Ions: Calorimetric Properties and Thermostability
Authors: Sartore Luciana , Penco Maurizio , Bigotti Fabio , Pedrotti Cristian , D'Antone Salvatore
Published: November 2004

Organic‐inorganic hybrid materials with excellent heavy metal ions chelating properties were synthesized by covalent bonding of multifunctional polymers of polyamidoamine (PAA) type onto silica. Two series of polyamidoamine‐silica hybrid materials differing in the PAA chemical structure were prepared and their thermal properties were investigated. Differential Scanning Calorimetry was used to study the effects of chain immobilization and ion chelation on the glass‐transition temperature (Tg) of the polymers. The Tg of PAA‐hybrid materials was elevated with respect to ungrafted PAAs. Complex formation with metal ions such as Cu++ or Co++ caused total suppression of Tg for both linear polymers as well as the corresponding hybrid materials. Finally, the silica particles slightly influenced the decomposition temperatures of linear polymers increasing their thermal stability.
Thermal Behavior of Composites Based on Poly(vinyl alcohol) and Sugar Cane Bagasse
Authors: Grillo Fernandes Elizabeth , Cinelli Patrizia , Chiellini Emo
Published: November 2004

Poly(vinyl alcohol) (PVA) and sugar cane bagasse (SCB) mixtures have been formulated as aimed at the production of hydro‐mulching composites and melt processed biobased composite items. Glycerol and urea have been proposed as suitable plasticizers and eventually, in the case of urea, for the realization also of slow release fertilizing hydro‐mulching. The investigation of thermal stability of raw components and relevant mixture is an important parameter to be assessed in view of processing and ultimate applications. PVA/SCB composites appeared suitable for melt processing up to 200°C. The urea containing PVA/SCB composites while resulted particularly suited for hydro‐mulching applications did not appear processable from the melt, due to urea thermal instability.
Alginate/Polyvinylalcohol Blends for Agricultural Applications: Structure‐Properties Correlation, Mechanical Properties and Greenhouse Effect Evaluation
Authors: Russo Roberto , Giuliani Anna , Immirzi Barbara , Malinconico Mario , Romano Gennaro
Published: November 2004

Biodegradable blend films containing sodium alginate, polyvinyl alcohol and glycerol, for agricultural applications, were prepared by casting of aqueous solutions. Since the mechanical properties of alginate are not suitable for agricultural applications, the addition of polyvinyl alcohol and glycerol was necessary in order to improve some mechanical parameters like the strain at break. The interaction between different components was studied by thermogravimetric analysis and DSC, while mechanical parameters and the transmittance in the IR region were investigated in order to identify the compositions with suitable properties for application in agriculture.
Segmented Polyurethanes for Medical Applications: Synthesis, Characterization and in vitro Enzymatic Degradation Studies
Authors: Ciardelli Gianluca , Rechichi Alfonsina , Cerrai Piero , Tricoli Mario , Barbani Niccoletta , Giusti Paolo
Published: November 2004

Degradable segmented poly(ether‐ester‐urethanes) of variable segment chemistry and content were synthesized and characterized. Polycaprolactone diol, a series of poly(ether‐ester) block copolymers, and a diisocyanate giving non toxic degradation products were used to form the prepolymer. Cyclohexane dimethanol and a L–phenylalanine–based diester (Phe diester) were used as chain extenders. The influence of α‐chimotrypsin on the degradation was investigated by exposing the polymers to buffer and enzyme solutions for 12 days. The SEM, SEC, and gravimetric results showed that a significant erosion of the Phe diester containing polymer compared with the control polyurethane occurred in the presence of the enzyme but not in a normal buffer solution.
Polyurethane Based Materials for the Production of Biomedical Materials
Authors: Covolan Vera L. , Di Ponzio Roberta , Chiellini Federica , Grillo Fernandes Elizabeth , Solaro Roberto , Chiellini Emo
Published: November 2004

Polyurethanes (PUs) composed by hard and soft segments have been extensively used in the manufacturing of biocompatible prosthesis and medical devices. A broad variety of PUs can be obtained by modifying the balance between both segments. In the present work, different basically‐flexible PUs have been prepared by employing different combinations of aliphatic hexamethylene diisocyanate, poly(ethylene glycol) (Mw 400 Da), poly(ϵ‐caprolactone) diol (Mw 530 Da), and 1,4‐butanediol. Thermal analysis of the synthesized PUs demonstrated high thermal stability and the assumption of glassy state well below room temperature, in agreement with their marked flexibility. Morphological characterization of PUs films indicated that films prepared by spin coating were smoother and more homogeneous than those obtained by casting. Biological assays performed by using 3T3/BALB‐C mouse embryo fibroblast cell line confirmed the absence of toxicity and hence the biocompatibility of PU‐films.
Polyelectrolyte Membranes Based on Sulfonated Syndiotactic Polystyrene in Its Clathrate Form
Authors: Borriello A. , Lavorgna M. , Malagnino N. , Mensitieri G. , Napoletano T. , Nicolais L.
Published: November 2004

Recently, more and more attention has been focused on new techniques for energy production also in view of environmental problems. A noticeable device is small fuel cell that converts chemical energy into electric energy by electrochemical reaction of hydrogen with oxygen, and exhibits a high‐energy efficiency. Conventional small fuel cells have been classified into phosphoric acid‐type fuel cells, molten carbonate‐type fuel cells, solid oxide‐type fuel cells, solid polymer type fuel cells, etc., according to the type of electrolyte used. The target of this work is the development of a new process to build up polyelectrolyte membranes, for polymer type fuel cell (PEM), by sulfonating syndiotactic polystyrene in its clathrate form. The polyelectrolyte membranes of this paper are inexpensive and exhibit good long‐term stability and ion exchange capability.
On the Physical Parameters and Relaxation Processes in Nematic Azobenzene Polymers for Optical Nanowriting
Authors: Andreozzi Laura , Faetti Massimo , Galli Giancarlo , Giordano Marco , Palazzuoli Diego
Published: November 2004

The possibility of achieving devices for rewritable optical storage is provided by liquid‐crystalline polymers with azobenzene side groups, because they undergo photochemically induced trans‐cis reversible isomerization. In this work we overview our investigations into a nematic azobenzene‐polymethacrylate (PMA4) as a suitable material for optical nanowriting. Relaxation processes over different time‐length scales are discussed with particular reference to understanding the interplay between homogeneity at the molecular level, bit stability and working temperature range.
Physical and Chemical Characterization of Cellulose Based Textiles Modified by Periodate Oxidation
Authors: Princi Elisabetta , Vicini Silvia , Pedemonte Enrico , Proietti Noemi , Capitani Donatella , Segre Anna Laura , D'Orazio Loredana , Gentile Gennaro , Polcaro Carmen , Martuscelli Ezio
Published: November 2004

Conversion of dihydroxyl groups to dialdehyde by periodate oxidation is a useful method widely used in derivatization of cellulose to activate the polymer to further reactions as grafting polymerization. To investigate the cellulose behavior at different level of oxidation and to better understand the influence of the crystallinity on the effects induced by oxidative reactions on different cellulose materials, linen and cotton textiles have been oxidized with periodate solutions in different conditions. Oxidized cellulose samples have been characterized by several techniques: solid‐state 13C NMR, Wide Angle X‐Ray diffraction, and SEM. Moreover the mechanical properties of the untreated and oxidized yarns have been evaluated by means of tensile tests, the oxidation degree has been measured by means of the hydroxylamine hydrochloride method.
Reactive Polymeric Dyes as Textile Auxiliaries
Authors: Altomare Angelina , Ciardelli Francesco , Solaro Roberto
Published: November 2004

Commercial and synthetic azobenzene derivatives were used for the synthesis of hydrophilic polymeric dyes. Two strategies based respectively on the polymerization of dye methacrylic derivatives with different monomers and on the functionalization of reactive polymers were investigated. Polymers containing rather small amounts of the selected dyes were generally obtained, very likely because of the electron withdrawing effect of azo chromophores. Almost quantitative conversions were recorded in the reaction of commercial dyes with maleic anhydride/methyl vinyl ether alternating copolymers. Some of the prepared polymeric dyes were preliminarily tested as textile finishing agents.
Multi‐Layer Pipes for Hydrocarbons Conveyance
Authors: Bulleri Barbara , Genoni Massimo , Gallone Giuseppe , Marchetti Augusto
Published: November 2004

The replacement of metals with plastics in piping systems is a well established practice in a vast range of public and industrial applications. However, difficulties still exist, mainly related to the limited chemical resistance of the polymers commonly used in pipe manufacturing to some conveyed fluids. This prevents using plastic pipes in important applications such as the transport of liquid hydrocarbons, particularly in oil fields. The use of chemically resistant polymers, such as fluorinated polyolefins, is precluded by high cost and poor mechanical properties. Co‐extrusion of multi‐layer pipes carrying an internal chemically resistant liner can be a viable alternative capable to extend the use of plastic pipes to refining and chemical industries. An experimental PE/PA multi‐layer pipe has been developed whose resistance to diffusion and mechanical properties have been tested. Tests in real oil fields confirm the good performance of the new pipes.
Single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization of vinyl chloride catalyzed by thiourea dioxide/octyl viologen in water/tetrahydrofuran at 25 °C
Authors: Percec Virgil , Popov Anatoliy V. , Ramirez‐Castillo Ernesto
Published: November 2004

The single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization (SET–DTLRP) of vinyl chloride (VC) in H2O/tetrahydrofuran at 25 °C catalyzed by thiourea dioxide [(NH2)2CSO2] is reported. This polymerization occurs only in the presence of a basic sodium bicarbonate (NaHCO3) buffer and the electron‐transfer cocatalyst octyl viologen. The resulting poly(vinyl chloride) (PVC) has a number‐average molecular weight of 1500–7000 and a weight‐average molecular weight/number‐average molecular weight ratio of 1.5. This PVC does not contain detectable amounts of structural defects and has both active chloroiodomethyl and inactive chloromethyl chain ends. Because of possible side reactions caused by the primary sulfoxylate anion (SO), the catalytic activity of (NH2)2CSO2 in the SET–DTLRP of VC is lower than that of the single‐electron‐transfer agent sodium dithionite. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 287–295, 2005
Apparent upfreezing of stones in late‐Pleistocene coversand, Bełchatów vicinity, Central Poland
Authors: Gozdzik Jan S. , French Hugh M.
Published: November 2004

Stones lie within a well‐sorted coversand in central Poland. They are thought to have migrated to their present positions by upfreezing that occurred as permafrost aggraded beneath an accumulating dune‐sand surface. Some of the stones have risen as much as 1 m into the coversand. ‘Chimney‐like’ sedimentary structures are thought to indicate the path of upward migration. The dynamics of upfreezing in non‐frost susceptible sediment are difficult to understand without recourse to site‐specific factors. Copyright © 2004 John Wiley & Sons, Ltd.
Randomized, Double‐Blind, Placebo‐Controlled, Dose‐Escalating Study of Aerosolized Interferon Gamma‐1b in Patients With Mild to Moderate Cystic Fibrosis Lung Disease
Authors: Moss Richard B. , Mayer‐Hamblett Nicole , Wagener Jeffrey , Daines Cori , Hale Kathryn , Ahrens Richard , Gibson Ronald L. , Anderson Paula , Retsch‐Bogart George , Nasr Samya Z. , Noth Imre , Waltz David , Zeitlin Pamela , Ramsey Bonnie , Starko Karen
Published: November 2004

Interferon gamma‐1b (IFN‐γ1b) is a pleiotropic cytokine with immunomodulatory activities that could decrease bacterial burden, inflammation, and obstruction in patients with CF. Patients with CF (≥12 years old, FEV1 ≥40% predicted) were randomly assigned to sequential dose cohorts inhaling 500 μg IFN‐γ1b, 1,000 μg IFN‐γ1b, or placebo by Respirgard II® nebulizer thrice weekly for 12 weeks. Sputum bacterial density and spirometry were measured. Safety, antibiotic use, hospitalization, and sputum neutrophils, elastase, DNA, IL‐8, and myeloperoxidase were also evaluated. Sixty‐six patients (mean age, 24 years, with mean baseline FEV1 of 74 ± 20 (SD) percent predicted) were studied. One patient had bronchospasm after the first dose of IFN‐γ1b; the overall withdrawal rate was 15% (5 in the placebo group, 2 in the 500‐μg IFN‐γ1b group, and 3 in the 1,000 μg IFN‐γ1b group). The 500‐μg IFN‐γ1b dose was well‐tolerated, but the 1,000‐μg dose cohort, who had a higher baseline bacterial density than placebo patients (mean difference, 1.2 log10 CFU/g sputum, 95% confidence interval (CI), 0.1,2.8, P = 0.04), had 24% more hospitalizations for exacerbation than placebo patients (95% CI, 2,45%, P = 0.05). There was a 0.12‐l difference between the 500‐μg IFN‐γ1b and placebo groups with respect to the 12‐week change in FEV1 (active group minus placebo group, 95% CI, −0.03,0.26, P = 0.11), as compared to a 0.01‐l difference between the 1,000‐μg IFN‐γ1b and placebo groups (95% CI, −0.16,0.17, P = 0.96). No effects of IFN‐γ1b were seen in sputum bacterial density or inflammatory biomarkers at 12 weeks. Aerosolized IFN‐γ1b did not improve pulmonary function, reduce sputum bacterial density, or affect inflammatory sputum markers in patients with mild‐moderate lung disease. Pediatr Pulmonol. 2005; 39:209–218. © 2004 Wiley‐Liss, Inc.
Effect of T‐R conformational change on sickle‐cell hemoglobin interactions and aggregation
Authors: Vaiana S. M. , Rotter M. A. , Emanuele A. , Ferrone F. A. , Palma‐Vittorelli M. B.
Published: November 2004

We compare the role of a conformational switch and that of a point mutation in the thermodynamic stability of a protein solution and in the consequent propensity toward aggregation. We study sickle‐cell hemoglobin (HbS), the β6 Glu‐Val point mutant of adult human hemoglobin (HbA), in its R (CO‐liganded) conformation, and compare its aggregation properties to those of both HbS and HbA in their T (unliganded) conformation. Static and dynamic light scattering measurements performed for various hemoglobin concentrations showed critical divergences with mean field exponents as temperature was increased. This allowed determining spinodal data points TS(c) by extrapolation. These points were fitted to theoretical expressions of the TS(c) spinodal line, which delimits the region where the homogeneous solution becomes thermodynamically unstable against demixing in two sets of denser and dilute mesoscopic domains, while remaining still liquid. Fitting provided model‐free numerical values of enthalpy and entropy parameters measuring the stability of solutions against demixing, namely, 93.2 kJ/mol and 314 J/°K‐mol, respectively. Aggregation was observed also for R‐HbS, but in amorphous form and above physiological temperatures close to the spinodal, consistent with the role played in nucleation by anomalous fluctuations governed by the parameter ϵ = (T − TS)/TS. Fourier transform infrared (FTIR) and optical spectroscopy showed that aggregation is neither preceded nor followed by denaturation. Transient multiple interprotein contacts occur in the denser liquid domains for R‐HbS, T‐HbS, and T‐HbA. The distinct effects of their specific nature and configurations, and those of desolvation on the demixing and aggregation thermodynamics, and on the aggregate structure are highlighted. Proteins 2005. © 2004 Wiley‐Liss, Inc.
Average peptide score: a useful parameter for identification of proteins derived from database searches of liquid chromatography/tandem mass spectrometry data
Authors: Chepanoske Cindy Lou , Richardson Bonnie E. , von Rechenberg Moritz , Peltier John M.
Published: November 2004

The quantity and variable quality of data that can be generated from liquid chromatography (LC)/mass spectrometry (MS)‐based proteomics analyses creates many challenges in interpreting the spectra in terms of the actual proteins in a complex sample. In spite of improvements in algorithms that match putative peptide sequences to MS/MS spectra, the assembly of these lists of possible or probable peptides into a ‘correct’ set of proteins is still problematic. We have observed a trend in a simple relationship, derived from standard database search outputs, which can be useful in assessing the quality of a MS/MS‐based protein identification. Specifically, the ratio of the protein score and number of non‐redundant peptides, or average peptide score (APS), can facilitate initial filtering of database search results in addition to providing a useful measure of confidence for the proteins identified. This parameter has been applied to results from the analysis of multi‐protein complexes derived from pull‐down experiments analyzed using a two‐dimensional LC/MS/MS workflow. In particular, the complex list of protein identifications derived from a drug affinity pull‐down with immobilized ampicillin and an E. coli lysate was greatly simplified by applying the APS as a filter, allowing for facile identification of the penicillin‐binding proteins known to interact with ampicillin. Furthermore, an APS threshold can be used for any data sets derived from electrospray ionization (ESI)‐ or matrix‐assisted laser desorption/ionization (MALDI)‐MS/MS experiments and is also not specific to any database search program. Copyright © 2004 John Wiley & Sons, Ltd.
Automated immobilized metal affinity chromatography/nano‐liquid chromatography/electrospray ionization mass spectrometry platform for profiling protein phosphorylation sites
Authors: Ficarro Scott B. , Salomon Arthur R. , Brill Laurence M. , Mason Daniel E. , Stettler‐Gill Michelle , Brock Ansgar , Peters Eric C.
Published: November 2004

A versatile integrated system has been developed for the automated enrichment and analysis of phosphopeptides by immobilized metal affinity chromatography/nano‐liquid chromatography/electrospray ionization mass spectrometry (IMAC/nano‐LC/ESI‐MS). This system utilizes two independently controlled high‐performance liquid chromatography (HPLC) pumps, an autosampler and microvalves to prepare and elute samples into an ion trap mass spectrometer. The use of robust reversed‐phase HPLC columns with integrated ESI emitter tips enables the reproducible detection and identification of low‐femtomole quantities of phosphopeptides. The entire system is coordinated through a simple user interface by customized software. The ruggedness of the system is demonstrated by highly reproducible analyses of single and multi‐protein digests, while its utility is demonstrated by the thorough evaluation of the relative immunoprecipitation efficiencies of several commercially available anti‐phosphotyrosine antibodies. Copyright © 2004 John Wiley & Sons, Ltd.
Validating regulatory‐compliant wide dynamic range bioanalytical assays using chip‐based nanoelectrospray tandem mass spectrometry
Authors: Wickremsinhe Enaksha R. , Ackermann Bradley L. , Chaudhary Ajai K.
Published: November 2004

Automated chip‐based infusion nanoelectrospray ionization coupled to tandem mass spectrometry (nanoESI‐MS/MS) was used to validate a bioanalytical assay conforming to United States Food and Drug Administration (FDA) regulatory guidelines and Good Laboratory Practices (GLP). Reboxetine was used as the analyte fortified in dog plasma along with an analog internal standard (IS). The best nanoESI response for reboxetine was observed with 90% acetonitrile (ACN)/water without any mobile phase modifiers. The analyte and IS were extracted from dog plasma samples by liquid‐liquid extraction (LLE). The supernatant was concentrated to dryness and redissolved in 90% ACN/water for nanoESI. Selected reaction monitoring (SRM) data were collected for all samples to generate ion current profiles with a base width of approximately 20 s. Selectivity experiments showed no interferences in blank plasma samples. Interferences as a result of in‐source collision‐induced dissociation of metabolites were not an issue due to the previously documented metabolism of reboxetine. Matrix suppression was evaluated across multiple lots of dog plasma as well as over different animal species (rabbit, rat, mouse) and different anticoagulants (heparin, EDTA). Matrix suppression ranged from approximately 30–60% across the different lots, species etc.; however, in all instances, the analyte and the IS were suppressed by similar amounts, suggesting the similarity in ionization properties between the two. A three‐batch validation was performed (each batch consisting of four different concentrations, six replicates of each concentration) and demonstrated inter‐assay accuracy (% relative error; RE) of less than ±8% and an inter‐assay precision (% relative standard deviation; RSD) of less than 7%, thus meeting regulatory guidelines. A comparison of analyses by nanoESI‐MS/MS and liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS) showed that nanoESI‐MS/MS had a greater slope for the calibration standard curve compared to LC/MS/MS, indicating greater sensitivity for the former technique. It is also noteworthy that the amount of sample infused during nanoESI‐MS/MS was approximately 80‐fold less compared to the amount of sample injected during LC/MS/MS. The absence of carryover (attributed to the lack of a common fluid path) in the nanoESI technique enabled the extension of the assay linear dynamic range to 500 000‐fold, and the possibility of analyzing samples in a single batch without the need for re‐analysis of samples with high concentrations. This technology offers the possibility for increased throughput for studies supporting drug development by providing fast data turnaround for assays conforming to regulatory guidelines and GLPs. Copyright © 2004 John Wiley & Sons, Ltd.
Further studies on the fragmentation of protonated ions of peptides containing aspartic acid, glutamic acid, cysteine sulfinic acid, and cysteine sulfonic acid
Authors: Men Lijie , Wang Yinsheng
Published: November 2004

Here we examined the fragmentation, on a quadrupole ion‐trap mass spectrometer, of the protonated ions of a group of peptides containing one arginine and two different acidic amino acids, one being aspartic acid (Asp) or glutamic acid (Glu) and the other being cysteine sulfinic acid [C(SO2H)] or cysteine sulfonic acid [C(SO3H)]. Our results showed that, upon collisional activation, the cleavage of the peptide bond C‐terminal to C(SO2H) is much more facile than that of the peptide bond C‐terminal to Asp, Glu, or C(SO3H). There is no significant difference, however, in susceptibility to cleavage of peptide bonds that are C‐terminal to Asp, Glu, and C(SO3H). To understand these experimental observations, we carried out B3LYP/6‐31G* density functional theory calculations for a model cleavage reaction of GXG → b2 + Gly, in which X is Asp, Glu, C(SO2H), or C(SO3H). Our calculation results showed that the cleavage reaction is thermodynamically more favorable when X = C(SO2H) than when X = Asp or C(SO3H). We attributed the less facile cleavage of the amide bond after Glu to that the formation of a six‐membered ring b ion for Glu‐bearing peptides is kinetically not as favorable as the formation of a five‐membered ring b ion for peptides containing the other three acidic amino acids. The results from this study may provide useful tools for peptide sequencing. Copyright © 2004 John Wiley & Sons, Ltd.
An age‐adjusted bootstrap‐based Poly‐k test
Authors: Moon Hojin , Ahn Hongshik , Kodell Ralph L.
Published: November 2004

The assumption of an asymptotic normal distribution of some test statistics may be invalid in certain dose–response trend tests. For instance, the survival‐adjusted Cochran–Armitage test, known as the Poly‐k test, is asymptotically standard normal under the null hypothesis. However, the asymptotic normality is not valid if there is a deviation from the tumour onset distribution that is assumed in this test or if the competing risks survival rates differ across groups. We develop an age‐adjusted bootstrap‐based method to assess the significance of assumed asymptotic normal tests for animal carcinogenicity data. The proposed method differs from conventional bootstrap methods in the aspect of preserving the mortality rate in each dose group under the null hypothesis of equal tumour incidence rates among the groups. We investigate an empirical distribution of the Poly‐3 (P3) trend test statistic using the proposed age‐adjusted bootstrap‐based method and compare it with the P3 test statistic referenced to the assumed standard normal distribution. A simulation study is conducted to evaluate the robustness of these tests to various Weibull‐family tumour onset distributions. The proposed method is applied to National Toxicology Program data sets to evaluate a dose‐related trend of a test substance on the incidence of neoplasms. Published in 2004 by John Wiley & Sons, Ltd.
The future for treatment by bone marrow transplantation for adrenoleukodystrophy, metachromatic leukodystrophy, globoid cell leukodystrophy and Hurler syndrome
Authors: Krivit W. , Lockman L. A. , Watkins P. A. , Hirsch J. , Shapiro E. G.
Published: November 2004

Within the past decade, bone marrow transplantation has been applied to over 200 patients worldwide with the intention of treating storage diseases. Bone marrow transplantation has provided a method for treatment of adrenoleukodystrophy, metachromatic leukodystrophy, globoid cell leukodystrophy and Hurler syndrome. After engraftment, significant improvement in the clinical course of each of these diseases occurs. Survival data of engrafted patients are superior to those of non‐transplanted. Engraftment and the resulting enzymatic reconstitution are concordant. Outcomes based on neuropsychological tests indicate continued maintenance and in some cases increase in cognitive function. Magnetic resonance imaging as well as spectroscopic examinations of the brain provide further evidence that positive changes occur in the central nervous system following long‐term engraftment. A better quality of life follows engraftment. Greater gains from use of bone marrow transplantation for these particular storage diseases will occur in the future. Earlier diagnosis will allow bone marrow transplantation in the presymptomatic stage at a younger age, providing an enhancement of positive effects noted from such treatment. At the same time, advances in bone marrow technology will serve to reduce the risk factors involved with the bone marrow transplantation process itself. These two factors taken together will be more than additive in providing benefits from use of bone marrow transplantation.
Neuropsychological outcomes of several storage diseases with and without bone marrow transplantation
Authors: Shapiro E. G. , Lockman L. A. , Balthazor M. , Krivit W.
Published: November 2004

Neuropsychological assessment is essential in providing documentation of the untreated natural history of storage diseases associated with dementia and quantifying the effectiveness of treatment on central nervous system function. Baseline characterization and outcome of bone marrow transplantation (BMT) for three leukodystrophies and three mucopolysaccharidoses are presented. Results suggests that BMT for Hurler syndrome, adrenoleukodystrophy, and globoid cell leukodystrophy can be effective in preventing dementia if done early enough in the disease. Sanfilippo and Hunter syndromes do not benefit and BMT is not recommended. For metachromatic leukodystrophy, BMT is not recommended for symptomatic early‐onset forms of the disease. Further longitudinal follow‐up is needed to determine whether the benefits outweigh the risks of BMT for late‐onset and preclinical metachromatic leukodystrophy.
Disorders of mitochondrial long‐chain fatty acid oxidation
Authors: Pollitt R. J.
Published: November 2004

The oxidation of long‐chain fatty acids requires a series of enzymes which are located in or on the mitochondrial membranes. These include carnitine palmitoyltransferases I and II, a carnitine‐acylcarnitine translocase and, newly discovered, very long‐chain acyl‐CoA dehydrogenase and the mitochondrial trifunctional protein. These last two chain‐shorten acyl‐CoA esters to the point where they can be transferred to the more soluble medium‐ and short‐chain‐specific enzymes within the mitochondrial matrix. The disorders of long‐chain fatty acid oxidation show a rather similar range of clinical and biochemical features, though with different emphasis in the different conditions. Patients with severe defects usually present early with acute attacks of hypoketotic hypoglycaemia and impaired liver function, or with cardiomyopathy or cardiac arrhythmia. In milder variants, skeletal myopathy with intermittent myoglobinuria develops later in life. 3‐Hydroxyacyl‐CoA dehydrogenase deficiency is unusual in producing peripheral neuropathy and retinitis pigmentosa. Treatment is based on the avoidance of fasting and replacement of normal dietary fat by medium‐chain triglyceride, the medium‐chain fatty acids entering the mitochondria in a carnitine‐independent manner and bypassing the long‐chain part of the spiral. Diagnosis must ultimately be based on direct assay of the enzyme involved, but preliminary indicators may come from determination of carnitine and intermediate metabolites in plasma, urinary organic acid profiling, and radioisotopic screening assays with lymphocytes or cultured fibroblasts.
Treatment of cystic fibrosis based on understanding CFTR
Authors: Smith A. E.
Published: November 2004

In the five years since the gene associated with cystic fibrosis was isolated, rapid progress has been made in understanding the structure and function of CFTR, the gene product. Based on the knowledge that CFTR is a cAMP‐regulated chloride channel in the apical surface of epithelia in many tissues, new approaches to treating CF disease have emerged. These include development of agents to open alternative chloride channels, to relocate mutant CFTR, which commonly is mislocalized because of a trafficking defect, and to deliver CFTR using protein or gene therapy. Although the underlying basis of each of these approaches is now well understood, major practical problems face each of them. Nevertheless, it is difficult not to be optimistic that new therapies will emerge.
Carrier screening in the community
Authors: Brock D. J. H.
Published: November 2004

A number of different models of cystic fibrosis (CF) carrier screening have now been tested in pilot trials. Apart from opportunistic and cascade testing (which are strictly speaking not true forms of screening), the major programmes have been directed either to young adults in primary care or to pregnant women in antenatal clinics. Only in the latter form of screening has sufficient data been collected to allow conclusions to be reached on the optimum mode of delivery. It seems very probable that when CF carrier screening passes into routine service, it will be the antenatal couple model that is used.
Glycine andl‐carnitine therapy in 3‐methylcrotonyl‐CoA carboxylase deficiency
Authors: Rutledge S. L. , Berry G. T. , Stanley C. A. , van Hove J. L. K. , Millington D.
Published: November 2004

Genetic deficiency of 3‐methylcrotonyl‐CoA carboxylase (3‐MCC) is a rare inborn error of leucine metabolism producing an organic acidaemia. With accumulation of 3‐methylcrotonyl‐CoA, there is increased production of 3‐hydroxyisovaleric acid, the glycine conjugate (3‐methylcrotonylglycine), and the carnitine conjugate (3‐hydroxyisovalerylcarnitine). These conjugates represent endogenous detoxification products. We studied excretion rates of these conjugates at baseline and with glycine and carnitine therapy in an 8‐year‐old girl with 3‐MCC deficiency. Her preadmission diet was continued. Plasma and urine samples were obtained after 24h of each of the following:l‐carnitine 100mg/kg per day and glycine 100, 175 and 250mg/kg per day. Plasma and urinary carnitine levels were reduced by 80% and 50%, respectively with abnormal urinary excretion patterns. These normalized with carnitine therapy. Acylcarnitine excretion increased with carnitine therapy. The glycine conjugate, 3‐methylcrotonylglycine (3‐MCG), was the major metabolite excreted at all times and its excretion increased with glycine therapy. Clearly, in 3‐MCC deficiency the available glycine and carnitine pools are not sufficient to meet the potential for conjugation of accumulated metabolites, suggesting a possible therapeutic role for glycine and carnitine therapy in this disorder.