bluuebunny/crossref_metadata_2025 huggingface dataset:
A Simple and Useful Synthetic Protocol for Selective Deprotection of tert‐Butyldimethylsilyl (TBS) Ethers
Authors: Khan Abu T. , Ghosh Subrata , Choudhury Lokman H.
Published: April 2004

A wide variety of tert‐butyldimethylsilyl ethers 1 can be easily cleaved to the corresponding parent hydroxyl compound 2 in the presence of 5 mol % of acetonyltriphenylphosphonium bromide (ATPB) at room temperature. In addition, tert‐butyldiphenylsilyl ethers can also be cleaved by using 20 mol % of the same catalyst. Alkyl tert‐butyldimethylsilyl ethers can be deprotected to the hydroxyl compounds chemoselectively in the presence of aryl tert‐butyldimethylsilyl ethers. Some of the major advantages are mild reaction conditions, no aqueous workup, high efficiency and chemoselectivity and compatibility with other protecting groups; no brominations occur in the aromatic ring under these experimental conditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Cover Picture: Transition Metal‐Catalyzed Carbon−Carbon Bond Formation with Grignard Reagents − Novel Reactions with a Classic Reagent (Eur. J. Org. Chem. 10/2004)
Authors: Shinokubo Hiroshi , Oshima Koichiro
Published: April 2004

The cover picture shows a concept that the combination of a Grignard reagent (RMgX) with various transition metal catalysts opens up an opportunity to explore new reactions for carbon−carbon bond formation. Grignard reagents are the most classical organometallics and useful compounds in organic synthesis. The addition of transition metal salts to this classic reagent gives novel reaction patterns such as carbometallation, rearrangement, electron transfer, cross‐coupling, and so forth. Manganese‐, chromium‐, iron‐, and cobalt‐catalyzed carbon−carbon bond formation reactions with Grignard reagents are discussed in the Microreview by H. Shinokubo and K. Oshima on p. 2081 ff.
Catalytic epoxide oxidation: a novel access to ﬂavouring and odorant α‐diketones
Authors: Antoniotti Sylvain , Alezra Nathalie , Fernandez Xavier , Duñach Elisabet
Published: April 2004

The catalytic oxidation of epoxides to α‐diketones provides a novel access to a variety of ﬂavouring compounds and odorants. This alternative synthetic strategy involves an oxidation reaction catalysed by commercially available reagents and affords four cyclic and acyclic α‐diketones presenting interesting organoleptic properties. The availability of epoxides, easily obtained by oleﬁn epoxidation, and the possibility of obtaining α‐diketones with a variety of structures gives a high potential to this method. Copyright © 2004 John Wiley & Sons, Ltd.
Regression methods for covariate adjustment and subgroup analysis for non‐censored cost‐effectiveness data
Authors: Willan Andrew R. , Briggs Andrew H. , Hoch Jeffrey S.
Published: April 2004

The current interest in undertaking cost‐effectiveness analyses alongside clinical trials has lead to the increasing availability of patient‐level data on both the costs and effectiveness of intervention. In a recent paper, we show how cost‐effectiveness analysis can be undertaken in a regression framework. In the current paper we develop a direct regression approach to cost‐effectiveness analysis by proposing the use of a system of seemingly unrelated regression equations to provide a more general method for prognostic factor adjustment with emphasis on sub‐group analysis. This more general method can be used in either an incremental cost‐effectiveness or an incremental net‐benefit approach, and does not require that the set of independent variables for costs and effectiveness be the same. Furthermore, the method can exhibit efficiency gains over unrelated ordinary least squares regression. Copyright © 2003 John Wiley & Sons, Ltd.
Circadian variations of bone marrow engraftability
Authors: D'Hondt Lionel , McAuliffe Christina , Damon Jeffrey , Reilly Judith , Carlson Jane , Dooner Mark , Colvin Gerald , Lambert Jean‐François , Hsieh Chung‐Cheng , Habibian Houri , Stencel Kimberly , Quesenberry Peter J.
Published: April 2004

Circadian rhythms exist for hematopoiesis, but little is known about circadian variation of bone marrow engraftability and host “acceptability”. Using a B6.SJL to C57BL/6J congenic transplant model, we chose 3‐times with light on: Hours After Light Onset (HALO) 4, 8, and 12 and 3‐times with light off: HALO 16, 20, and 24. The mice were conditioned on a 12‐h light/dark cycles. Recipient mice (100 cGy) received 40 million cells. We demonstrated a significant variation of bone marrow engraftability into bone marrow, spleen, and thymus when donor animals were subjected to changes in their light/dark cycles. Two statistically significant nadirs in all three organs were observed at HALO 8 and 24 in experiments carried out in July, while an identical set of experiments in February analyzing engraftment in marrow and spleen showed nadirs at HALO 8, but not at HALO 24. Marrow progenitors from the July experiments showed nadirs at HALO 12 and 24. The percentage of progenitors in S phase peaked at HALO 8 and 24. Interestingly, there were no changes in the ability of host to accept grafts with changes in the light/dark cycles of host animals. Circadian variations of bone marrow engraftability are important and should be considered in bone marrow transplant strategies. © 2004 Wiley‐Liss, Inc.
The application of the acoustic spectrophonometer to biomolecular spectrometry: a step towards acoustic ‘fingerprinting’
Authors: Stevenson A. C. , Araya‐Kleinsteuber B. , Sethi R. S. , Mehta H. M. , Lowe C. R.
Published: April 2004

A tunable acoustic biosensor for investigating the properties of biomolecules at the solid–liquid interfaces is described. In its current, format the device can be tuned to frequencies between 6.5 MHz and 1.1 GHz in order to provide a unique detection feature: a variable evanescent wave thickness at the sensor surface. The key to its successful implementation required the careful selection of antennae designs that could induce shear acoustic waves at the solid–liquid interface. This non‐contact format makes it possible to recover resonant shear acoustic waves over 100 different harmonic frequencies as a result of the electrical characteristics of the spiral coil. For testing this multifrequency sensing concept the surface of a quartz disc was exposed to solutions of immunoglobulin G (IgG) to form an adsorbed monolayer, whence protein A and IgG were added again in order to form multilayers. Spectra at frequencies between 6 and 600 MHz were generated for each successive layer and revealed two characteristic phases: an initial phase at the low megahertz frequencies consistent with the conventional Sauerbrey relation, and a possible additional phase towards the high megahertz to gigahertz frequencies, that we believe relates to the structure of the biomolecular film. This two‐phase behaviour evident from differences between high and low frequencies, rather than from any distinct frequency transition, was anticipated from the reduction in evanescent wave thickness down to nanometre dimensions, and thin film resonance phenomena that are known to occur for film and fluid systems. These measurements suggested that the single element acoustic biosensor we present here may form the basis from which to generate acoustic molecular spectra, or ‘acoustic fingerprints’, in a manner akin to optical spectroscopy. Copyright © 2004 John Wiley & Sons, Ltd.
The tunnelling conductance of molecularly ordered metalloprotein arrays
Authors: Davis J. J. , Wrathmell C. L. , Zhao J. , Fletcher J.
Published: April 2004

Metalloproteins can be self‐assembled in molecularly ordered, electrochemically addressable arrays. We report here on a study of the transport characteristics of the blue copper protein, azurin, from Pseudomonas aeruginosa, by a combination of electrochemical and scanning probe techniques (scanning tunnelling microscopy and conducting atomic force microscopy). Redox‐switchable chemisorbed molecular arrays can be formed from both wild‐type and mutant proteins using the strong affinity of cysteine residue thiolates for pristine gold surfaces. The molecular transconductance of single protein molecules within these arrays has been studied under controllable conditions where it has been additionally possible to resolve the effects of protein mechanical perturbation. Although tunnelling appears to be non‐resonant and adequately explained through the use of a square barrier model, under some conditions the contribution of the redox‐active copper centre to conductance is resolvable. Copyright © 2004 John Wiley & Sons, Ltd.
Design of a Medical Non‐Linear Drilling Device: The Influence of Twist and Wear on the Fatigue Behaviour of NiTi Wires Subjected to Bending Rotation
Authors: Wagner M. , Richter J. , Frenzel J. , Grönemeyer D. , Eggeler G.
Published: April 2004

This paper considers fundamental and experimental aspects associated with the engineering design of a medical, non‐linear drilling device which exploits shape memory pseudoelasticity of NiTi wires. For this application it is important that the NiTi wires have a good fatigue resistance. This is why the present authors have previously determined the influence of various parameters on cyclic life, crack growth and stress state of pseudoelastic wires subjected to bending rotation fatigue. The actual drilling device has to withstand twist in addition to bending rotation because the free rotation is constrained by friction between the drill head and the bone material. In addition, friction between the wire and a NiTi guiding tube results in wear and this may well promote fatigue crack nucleation. In this paper, we explain the function of the medical drill. We then report results on the effect of the additional parameters (1) twist and (2) wear on the fatigue life of thin pseudoelastic NiTi wires. We finally discuss the implications of our experimental results for the design process of the medical drilling device.
New drugs and treatment for respiratory syncytial virus
Authors: Maggon Krishan , Barik Sailen
Published: April 2004

The respiratory syncytial virus (RSV) is a global health problem affecting infants and the elderly and claiming more lives than AIDS in many parts of the world. Only two antibody drugs are approved for its prevention, and ribavarin, a relatively nonspecific antiviral, is used for treatment. In the mid‐1990s, a number of pharmaceutical and biotech companies initiated research programs against RSV. Together, the academic and the industrial R&D covered the whole spectrum of antibodies, vaccines, synthetic small molecule antiviral and antisense technology, and at one point, accounted for at least 25 active R&D programs. However, coincident to the marketing of the monoclonal antibody palivizumab (Synagis®) in 1998, a sharp decline in such projects ensued. Many companies recently cancelled RSV projects during a prioritisation of their R&D portfolios although the continuing medical need, large market size and sales projections clearly indicate that a safe and effective RSV drug or vaccine is likely to attain blockbuster status. Today RSV receives an insignificant fraction of the R&D budget compared with AIDS, for example. This article reviews the present status of the anti‐RSV regimen, covers drugs in the market and in development, and attempts to link basic research to industrial drug development, animal models of RSV, clinical trials, current clinical management, and present and future market projections. It is hoped that the unmet medical need of the victims of RSV will encourage continued involvement of the pharmaceutical and biotechnology industry in developing safe and effective prevention and treatments for RSV. Copyright © 2004 John Wiley & Sons, Ltd.
Generalized log‐rank test for mixed interval‐censored failure time data
Authors: Zhao Qiang , Sun Jianguo
Published: April 2004

This paper considers the problem of non‐parametric treatment comparisons when mixed interval‐censored failure time data are available, which often occurs in clinical trials and epidemiological studies. By mixed interval‐censored data, we mean that the survival time of interest is observed to belong to an interval or to be right‐censored. For the problem, we generalize the most commonly used log‐rank test for right‐censored survival data. Numerical studies are conducted and reported to evaluate and compare the proposed test with the existing method, which indicate that the presented method works well. We apply the method to a data set arising from an AIDS cohort study, that motivated the study. Copyright © 2004 John Wiley & Sons, Ltd.
Conflicts of interest in data monitoring of industry versus publicly financed clinical trials
Authors: Lachin John M.
Published: April 2004

The FDA Guidance, while highly appropriate for industry sponsored trials, need not be imposed on publicly (e.g. NIH) financed clinical trials. While the potential for conflicts of interest exist in the latter, they are in general manageable and pose an acceptable low risk of threatening the integrity of a study. However, the Guidance should heighten the awareness of all investigators in public trials to the potential for the appearance of conflicts and to the need for full and open participation in the management of dualities of interest. Copyright © 2004 John Wiley & Sons, Ltd.
Playing safe and preserving integrity: making the FDA model work
Authors: Wittes Janet
Published: April 2004

The proposed FDA model for Data Monitoring Committees (DMC) includes the recommendation to separate the reporting statistician from the co‐ordinating centre statistician. The former writes reports for the DMC; the latter is the statistician responsible for the statistical design of the trial, its ongoing day‐to‐day operation, and the final analysis of the data. This model, while protecting the scientific integrity of the trial, risks producing inadequate reports to the DMC unless the reporting statistician understands the trial and the database. This brief paper describes methods by which the reporting statistician can gain the knowledge necessary to produce informative reports. It also emphasizes that reports produced for the purpose of making decisions during the course of a trial differ in purpose, and should therefore differ in form, from reports summarizing the data and results at the end of the trial. Copyright © 2004 John Wiley & Sons, Ltd.
Independence of the statistician who analyses unblinded data
Authors: Siegel Jay P. , O'Neill Robert T. , Temple Robert , Campbell Gregory , Foulkes Mary A.
Published: April 2004

This discussion considers arguments for and against separating responsibility for the unblinded interim analysis of a clinical trial from responsibility for trial management and modifications to the ongoing trial. The degree to which one or different statisticians carry out these responsibilities and thus the degree of statistician independence for the two activities can vary, but a sponsor should recognize that giving a single statistician both responsibilities might limit flexibility in managing the trial, particularly with respect to modifying an ongoing trial. Published in 2004 by John Wiley & Sons, Ltd.
The role of the unblinded sponsor statistician
Authors: Snapinn Steven , Cook Thomas , Shapiro Deborah , Snavely Duane
Published: April 2004

In clinical trials sponsored by Merck the unblinded statistician is typically an employee of the company. From a pharmaceutical industry perspective, advantages of this approach include ensuring that the unblinded statistician is knowledgeable regarding the experimental treatments, therapeutic area and study objectives; that the quality of the analysis conforms to rigorous standards; and that the allocation schedule, database and interim results are kept confidential. These advantages are felt to outweigh any potential disadvantages. Copyright © 2004 John Wiley & Sons, Ltd.
Developing scholarly teaching and the scholarship of teaching and learning through faculty learning communities
Authors: Richlin Laurie , Cox Milton D.
Published: April 2004

The scholarship of teaching and learning has been a primary motivator and focus of faculty learning communities. This chapter reports on the strategies, processes, and activities that foster this scholarship in FLCs.
A thermogravimetric analysis study of volatilization of flux mixtures used in XRF sample preparation
Authors: Loubser Maggi , Strydom Christien , Potgieter Herman
Published: April 2004

This paper deals with the thermal behaviour occurring during the formation of lithium borate glasses. Thermogravimetric analysis and differential scanning calorimetry were employed to identify reactions occurring during fusion in pure flux mixtures. The conditions around the identified reactions were reproduced in a muffle furnace to obtain larger quantities of material for further investigation using spectroscopic techniques. It was shown that above 1050°C lithium borate fluxes volatilize, which could lead to inaccurate analytical results. Copyright © 2004 John Wiley & Sons, Ltd.
Benthic primary production in two perennially ice-covered Antarctic lakes: patterns of biomass accumulation with a model of community metabolism
Authors: Hawes I. , Moorhead D. , Sutherland D. , Schmeling J. , Schwarz A.-M.
Published: April 2004

A mathematical model was used to simulate interannual patterns of biomass accumulation within benthic microbial mats of two Antarctic lakes. Lakes Hoare and Vanda are in the Dry Valley region of Southern Victoria Land, and are both perennially ice covered. The model combines experimentally derived observations of light/photosynthesis relationships and rates of respiration of mats from a range of depths in these lakes, with data on incident radiation and the optical properties of the ice and water column. The model was used to estimate daily and annual production and, using measured carbon content, the potential vertical accumulation of the mats over a year. An annual pattern of photosynthesis was predicted for both lakes, with net production from October to February and net respiration at other times. Predicted rates and patterns of net photosynthesis were remarkably similar in the two lakes, despite differences in light climate: the ice of Lake Hoare transmits 1–4% incident radiation, whereas that of Lake Vanda transmits up to 20%. Maximum daily rates of 15–20 μg carbon cm−2 were predicted to occur at approximately 10 m depth in both lakes. Maximum annual rates of carbon fixation (at 10–12 m depth) in both lakes were c. 1.2 mg carbon cm−2 equating to approximately 0.1–4 mm vertical accumulation of mat each year. Experimental studies of microbial mats in the lakes revealed horizontal laminations of similar thickness to model estimates, supporting the hypothesis that these were annual layers. Differences between model estimates and observations were found in deeper water in Lake Vanda, where considerably more material accumulated than was predicted.
Age of Pre-Break-Up Gondwana Magmatism
Authors: Riley Teal R. , Knight Kim B.
Published: April 2004

Extensive outpourings of basalt, and to a lesser extent rhyolite, are closely associated with continental break-up and plume–lithosphere interactions. The Gondwana supercontinent began to fragment during Early–Middle Jurassic times and was associated with the eruption of over three million km3 of dominantly basaltic magma. This intense magmatic episode is recorded in volcanic rocks of the Karoo (Africa), Ferrar (Antarctica) and Chon Aike (South America). K–Ar and Rb–Sr whole rock geochronology has consistently failed to produce reliable ages for these volcanic rocks, but in the last four years, the wider application of single grain 40Ar/39Ar and/or U–Pb geochronology has produced more robust and precise dating of the magmatism. This paper reviews the recent advances in high precision geochronology and provides a full recalibrated 40Ar/39Ar dataset. Application of these methods across the majority of the volcanic provinces indicates that approximately 80% of the volcanic rocks were erupted within a short, 3–4 Myr period at c. 182 Ma. This burst of magmatism occurred in the Karoo province at c. 183 Ma and in the Ferrar provinces at c. 180 Ma, and was dominated by mafic volcanism. This peak in volcanism is coincident with a second order mass extinction event at the end of the Pliensbachian when c. 5% of marine families were wiped out coinciding with widespread oceanic anoxia in the early Toarcian. A prolonged period of silicic volcanism occurred along the proto-Pacific margin, prior to, and during the main phase of break-up. Silicic volcanism was initially coincident with the plume related Karoo-Ferrar provinces, but continued over c. 40 Myr, associated with lithospheric extension and subduction along the proto-Pacific continental margin.
Dissolved carbohydrates in Antarctic sea ice
Authors: Herborg L.-M. , Thomas D.N. , Kennedy H. , Haas C. , Dieckmann G.S.
Published: April 2004

Concentrations of dissolved monocarbohydrates (MCHO) and polycarbohydrates (PCHO) were analysed in a variety of ice habitats from summer Weddell Sea sea ice (surface ponds, ice cores, gap layers and platelet ice). The dissolved organic carbon (DOC) pool in these habitats was also measured and the contribution of carbohydrate to this pool was assessed. The DOC concentrations within all sea ice habitats were high compared to surface seawater concentrations with values up to 958μMC being measured. Total carbohydrates (TCHO) were highest in the ice cores and platelet ice samples, up to 31% of the DOC pool, a reflection of the high algal biomass in these two habitat classes. TCHO in the other habitats ranged between 10% and 29% of DOC. The ratios of MCHO to PCHO varied considerably between the ice habitats: in surface ponds and ice cores MCHO was 70% of the TCHO pool, whereas in gap layers and platelet ice there were lower PCHO concentrations resulting in MCHO being 88% of TCHO.
Landscape development in western and central Dronning Maud Land, East Antarctica
Authors: Näslund Jens-Ove
Published: April 2004

Large-scale bedrock morphology and relief of two key areas, the Jutulsessen Nunatak and the Jutulstraumen ice stream are used to discuss glascial history and landscape development in western and central Dronning Maud Land, Antarctica. Two main landform components were identified: well-defined summit plateau surfaces and a typical alpine glacial landscape. The flat, high-elevation plateau surfaces previously were part of one or several continuous regional planation surfaces. In western Dronning Maud Land, overlying cover rocks of late Palaeozoic age show that the planation surface(s) existed in the early Permian, prior to the break-up of Gondwana. A well-develoment escarpment, a mega landform typical for passive continental margins, bounds the palaeosurface remnants to the north for a distance of at least 700 km. The Cenozoic glacial landscape, incised in the palaeosurface and escarpment, is exemplified by Jutulsessen Nunatak, where a c. 1.2 km deep glacial valley system is developed. However, the prominent Penck-Jutul Trough represents some of the deepest dissection of the palaeosurface. This originally tectonic feature is today occupied by the Jutulstraumen ice stream. New topographic data show that the bed of the Penck-Jutul Trough is situated 1.9±1.1 km below sea level, and that the total landscape relief is at least 4.2 km. Today's relief is a result of several processes, including tectonic faulting, subaerial weathering, fluvial erosion, and glacial erosion. It is probable that erosion by ice streams has deepened the tectonic troughs of Dronning Maud Land since the onset of ice sheet glaciation in the Oligocene, and continues today. An attempt is made to identify major events in the long-term landscape development of Dronning Maud Land, since the break-up of the Gondwana continent.
A New Class of Tricyclic Diterpenes from Eremophila georgei (Myoporaceae)
Authors: Syah Yana M. , Ghisalberti Emilio L. , Skelton Brian W. , White Allan H.
Published: April 2004

The first example of a new class of tricyclic diterpenes together with two new
viscidanes have been isolated from a variety
ofEremophila georgei. The structures of the viscidane
compounds were assigned on the basis of spectroscopic data and comparison with
model compounds. The structure and relative stereochemistry of the lactone
(2), which represents a new diterpene skeleton, were established by
spectroscopic and X-ray crystallographic methods. The derivation of (2) from a
viscidane is suggested.
Modular construction of a signaling scaffold: MORG1 interacts with components of the ERK cascade and links ERK signaling to specific agonists
Authors: Vomastek Tomas , Schaeffer Hans-Joerg , Tarcsafalvi Adel , Smolkin Mark E. , Bissonette Eric A. , Weber Michael J.
Published: April 2004

Signal transduction occurs by the reversible assembly of oligomeric protein complexes that include both enzymatic proteins and proteins without known enzymatic activity. These nonenzymatic components can serve as scaffolds or anchors and regulate the efficiency, specificity, and localization of the signaling pathway. Here we report the identification of MORG1 (mitogen-activated protein kinase organizer 1), a member of the WD-40 protein family that was isolated as a binding partner of the extracellular signal-regulated kinase (ERK) pathway scaffold protein MP1. MORG1 specifically associates with several components of the ERK pathway, including MP1, Raf-1, MEK, and ERK, and stabilizes their assembly into an oligomeric complex. MORG1 facilitates ERK activation when cells are stimulated with lysophosphatidic acid, phorbol 12-myristate 13-acetate, or serum, but not in response to epidermal growth factor. Suppression of MORG1 by short interfering RNA leads to a marked reduction in ERK activity when cells are stimulated with serum. We propose that MORG1 is a component of a modular scaffold system that participates in the regulation of agonist-specific ERK signaling.
Close agreement between the orientation dependence of hydrogen bonds observed in protein structures and quantum mechanical calculations
Authors: Morozov Alexandre V. , Kortemme Tanja , Tsemekhman Kiril , Baker David
Published: April 2004

Hydrogen bonding is a key contributor to the exquisite specificity of the interactions within and between biological macromolecules, and hence accurate modeling of such interactions requires an accurate description of hydrogen bonding energetics. Here we investigate the orientation and distance dependence of hydrogen bonding energetics by combining two quite disparate but complementary approaches: quantum mechanical electronic structure calculations and protein structural analysis. We find a remarkable agreement between the energy landscapes obtained from the electronic structure calculations and the distributions of hydrogen bond geometries observed in protein structures. In contrast, molecular mechanics force fields commonly used for biomolecular simulations do not consistently exhibit close correspondence to either quantum mechanical calculations or experimentally observed hydrogen bonding geometries. These results suggest a route to improved energy functions for biological macromolecules that combines the generality of quantum mechanical electronic structure calculations with the accurate context dependence implicit in protein structural analysis.
Fluid-dynamical basis of the embryonic development of left-right asymmetry in vertebrates
Authors: Cartwright Julyan H. E. , Piro Oreste , Tuval Idan
Published: April 2004

Experimental work in developmental biology has recently shown in mice that fluid flow driven by rotating cilia in the node, a structure present in the early stages of growth of vertebrate embryos, is responsible for determining the normal development of the left-right axis, with the heart on the left of the body, the liver on the right, and so on. The role of physics, in particular, of fluid dynamics, in the process is one of the important questions that remain to be answered. We show with an analysis of the fluid dynamics of the nodal flow in the developing embryo that the leftward flow that has been experimentally observed may be produced by the monocilia driving it being tilted toward the posterior. We propose a model for morphogen transport and mixing in the nodal flow and discuss how the development of left-right asymmetry might be initiated.
Arylamine N-Acetyltransferase Is Required for Synthesis of Mycolic Acids and Complex Lipids in Mycobacterium bovis BCG and Represents a Novel Drug Target
Authors: Bhakta Sanjib , Besra Gurdyal S. , Upton Anna M. , Parish Tanya , Sholto-Douglas-Vernon Carolyn , Gibson Kevin J.C. , Knutton Stuart , Gordon Siamon , daSilva Rosangela P. , Anderton Matthew C. , Sim Edith
Published: April 2004

Mycolic acids represent a major component of the unique cell wall of mycobacteria. Mycolic acid biosynthesis is inhibited by isoniazid, a key frontline antitubercular drug that is inactivated by mycobacterial and human arylamine N-acetyltransferase (NAT). We show that an in-frame deletion of Mycobacterium bovis BCG nat results in delayed entry into log phase, altered morphology, altered cell wall lipid composition, and increased intracellular killing by macrophages. In particular, deletion of nat perturbs biosynthesis of mycolic acids and their derivatives and increases susceptibility of M. bovis BCG to antibiotics that permeate the cell wall. Phenotypic traits are fully complemented by introduction of Mycobacterium tuberculosis nat. We infer from our findings that NAT is critical to normal mycolic acid synthesis and hence other derivative cell wall components and represents a novel target for antituberculosis therapy. In addition, this is the first report of an endogenous role for NAT in mycobacteria.
Ribosomal S6 Kinase as a Mediator of Keratinocyte Growth Factor-induced Activation of Akt in Epithelial Cells
Authors: Pan Zhong-Zong , Devaux Yvan , Ray Prabir
Published: April 2004

The keratinocyte growth factor receptor (KGFR) is a member of the fibroblast growth factor receptor (FGFR) superfamily. The proximal signaling molecules of FGFRs are much less characterized compared with other growth factor receptors. Using the yeast two-hybrid assay, we have identified ribosomal S6 kinase (RSK) to be a protein that associates with the cytoplasmic domain of the KGFR. The RSK family of kinases controls multiple cellular processes, and our studies for the first time show association between the KGFR and RSK. Using a lung-specific inducible transgenic system we have recently demonstrated protective effects of KGF on the lung epithelium and have demonstrated KGF-induced activation of the prosurvival Akt pathway both in vivo and in vitro. Here we show that a kinase inactive RSK mutant blocks KGF-induced Akt activation and KGF-mediated inhibition of caspase 3 activation in epithelial cells subjected to oxidative stress. It was recently shown that RSK2 recruits PDK1, the kinase responsible for both Akt and RSK activation. When viewed collectively, it appears that the association between the KGFR and RSK plays an important role in KGF-induced Akt activation and consequently in the protective effects of KGF on epithelial cells.
Neoteny or not? The distribution of the hypophysial duct within the Galaxioidea
Authors: Suter H. C. , Kennedy M. , Young G.
Published: April 2004

The hypophysial duct, a hollow tube of tissue linking the pituitary gland and the buccal cavity, was found in adults of all the galaxiid genera examined except Aplochiton and Paragalaxias. The pituitary structure in these genera, however, indicated that the duct was probably once present and has been subsequently lost. The duct was absent in the other galaxioid families, Retropinnidae and Lepidogalaxiidae. Mapping the distribution of the duct onto a DNA sequence‐based phylogeny suggests that the embryological duct was retained in a galaxiid ancestral to Aplochiton, with subsequent losses in Aplochiton and Paragalaxias.
Self‐esteem, perception of relationships, and emotional distress: A cross‐cultural study
Authors: Abe Jo Ann A.
Published: April 2004

This study examined the relative importance of self‐esteem, family cohesion, and support from friends in predicting depressed mood and anxiety in Japanese and American college students. Contrary to expectations, self‐esteem was the strongest predictor of emotional distress in both groups of students. Nevertheless, consistent with predictions derived from Markus and Kitayama's theory of self‐construals, family cohesion accounted for a significantly larger percentage of the variance in predicting emotional distress in Japan than in the United States. In both countries, the relations between support from friends and the measures of emotional distress were entirely mediated by self‐esteem. However, among Japanese students, family cohesion accounted for additional significant variance in predicting the measures of emotional distress, even after controlling for self‐esteem.
The Power‐law Mathematical Model for Blood Damage Prediction: Analytical Developments and Physical Inconsistencies
Authors: Grigioni Mauro , Daniele Carla , Morbiducci Umberto , D’Avenio Giuseppe , Di Benedetto Giacomo , Barbaro Vincenzo
Published: April 2004

Abstract:  Blood trauma caused by medical devices is a major concern. Complications following the implantation/application of devices such as prosthetic heart valves, cannulae, blood pumps, tubing, and throttles lead to sublethal and lethal damage to platelets and erythrocytes.

This damage is provided by the alterations in fluid dynamics, providing a mechanical load on the blood corpuscle's membrane by means of the shear stress. An appropriate quantification of the shear‐induced hemolysis of artificial organs is thought to be useful in the design and development of such devices in order to minimize device‐induced blood trauma. To date, a power‐law mathematical relationship using the time of exposure of a blood corpuscle to a certain mechanical load and the shear stress itself (derived under the peculiar condition of uniform shear stress) has served as a basic model for the estimation of the damage to blood, investigated by means of numerical and/or experimental fluid dynamical techniques. The aim of the present article is to highlight the effect of a time‐varying mechanical loading acting on blood cells based on the usual power‐law model; furthermore, the effect of the loading history of a blood particle is discussed, showing how the past history of the shear acting on a blood corpuscle is not taken into account, as researchers have done until now. The need for a reassessment of the power‐law model for potential blood trauma assessment is discussed by using a mathematical formulation based on the hypotheses of the existence of damage accumulation for blood with respect to time and with respect to shear stress, to be applied in complex flow fields such as the ones established in the presence of artificial organs.
Automatic System for Noninvasive Blood Pressure Determination in Rotary Pump Recipients
Authors: Schima Heinrich , Boehm Herbert , Huber Leopold , Schmallegger Helmut , Vollkron Michael , Hiesmayr Michael , Noisser Robert , Wieselthaler Georg
Published: April 2004

Abstract:  In patients with implanted rotary pumps, the arterial pressure pulsatility is usually far lower than in normal individuals. Depending on the remaining degree of pulsatility, cuff‐based systems such as the classical Riva–Rocci‐determination of arterial blood pressure and correlated sounds or pressure measurements based on cuffpressure oscillations become inaccurate or even impossible. Therefore, a system was developed which evaluates the flow in the radial artery using an ultrasound wristwatch sensor, and this additional information is used for pressure determination. A computerized data acquisition and cuff‐control system based on a PC using Matlab software, a wristwatch ultrasound device, and a compressor‐driven pressure cuff was set up. The cuff was controlled for automatic inflation and deflation cycles. Cuff pressure and arterial flow was recorded. Several algorithm strategies were developed, which gave data for systolic blood pressure and heart rate together with a reliability index for data quality. Finally, the new algorithms were implemented in a microcontroller system. Comparisons with invasive measurements showed excellent correlation with systolic blood pressure (mean ΔP −0.3 mm Hg, n = 28). During exercise of rotary pump patients and therefore enhanced pulsatility the difference from manual evaluation was −2.1 mm Hg (n = 18). In conclusion, adaptation of the classical cuff‐pressure method with ultrasound evaluation of peripheral flow allows reliable determination of blood pressure in patients with low pulsatility resulting from implanted rotary cardiac assist pumps. By development of a wristwatch sensor and an automatic control system a robust method for daily use could be  developed.
Role of oxidative stress in intermittent hypoxia‐induced immediate early gene activation in rat PC12 cells
Authors: Yuan Guoxiang , Adhikary Gautam , McCormick Andrew A. , Holcroft John. J. , Kumar Ganesh K. , Prabhakar Nanduri R.
Published: April 2004

Intermittent hypoxia (IH) occurs in many pathophysiological conditions. The molecular mechanisms associated with IH, however, have received little attention. Previous studies have reported that the c‐fos gene via formation of activator protein‐1 (AP‐1) transcription factor contributes to adaptive responses to continuous hypoxia. In the present study, using a cell culture model we examined whether IH activates c‐fos and AP‐1 and if so, by what mechanisms. Experiments were performed on rat phaeochromocytoma cells exposed to 21% O2 (normoxia) or 60 and 120 cycles of IH, each cycle consisting 15 s of hypoxia followed by 4 min of normoxia. IH resulted in a significant elevation of c‐fos mRNA as well as transcriptional activation. IH was more potent and induced a longer lasting activation of c‐fos than comparable cumulative duration of continuous hypoxia. IH increased AP‐1 activity and tyrosine hydroxylase (TH) mRNA, an AP‐1‐regulated downstream gene, and these effects were prevented by antisense c‐fos. Superoxide dismutase mimetic, a potent scavenger of superoxide anions, prevented IH‐induced c‐fos, AP‐1 and TH activations. IH increased superoxide anion levels in mitochondria as evidenced by decreased aconitase enzyme activity and increased levels of hydrogen peroxide, a stable dismutated product of superoxide anions. Complex I of the mitochondrial electron transport chain was markedly inhibited in IH exposed cells. Pharmacological inhibitors of complex I mimicked the effects of IH during normoxia and occluded the effects of IH on c‐fos activation, suggesting the involvement of the mitochondrial electron transport chain in the generation of superoxide anions during IH. These results suggest IH‐induced c‐fos‐mediated transcriptional activation involves oxidative stress.
Amino terminal glutamate residues confer spermine sensitivity and affect voltage gating and channel conductance of rat connexin40 gap junctions
Authors: Musa Hassan , Fenn Edward , Crye Mark , Gemel Joanna , Beyer Eric C. , Veenstra Richard D.
Published: April 2004

Connexin40 (Cx40) contains a specific binding site for spermine (affinity ∼100 μm) whereas connexin43 (Cx43) is unaffected by identical concentrations of intracellular spermine. Replacement of two unique glutamate residues, E9 and E13, from the cytoplasmic amino terminal domain of Cx40 with the corresponding lysine residues from Cx43 eliminated the block by 2 mm spermine, reduced the transjunctional voltage (Vj) gating sensitivity, and reduced the unitary conductance of this Cx40E9,13K gap junction channel protein. The single point mutations, Cx40E9K and Cx40E13K, predominantly affected the residual conductance state (Gmin) and Vj gating properties, respectively. Heterotypic pairing of Cx40E9,13K with wild‐type Cx40 in murine neuro2A (N2A) cells produced a strongly rectifying gap junction reminiscent of the inward rectification properties of the Kir (e.g. Kir2.x) family of potassium channels. The reciprocal Cx43K9,13E mutant protein exhibited reduced Vj sensitivity, but displayed much less rectification in heterotypic pairings with wtCx43, negligible changes in the unitary channel conductance, and remained insensitive to spermine block. These data indicate that the connexin40 amino terminus may form a critical cytoplasmic pore‐forming domain that serves as the receptor for Vj‐dependent closure and block by intracellular polyamines. Functional reciprocity between Cx40 and Cx43 gap junctions involves other amino acid residues in addition to the E or K 9 and 13 loci located on the amino terminal domain of these two connexins.
Locomotor‐dependent and ‐independent components to hypocretin‐1 (orexin A) regulation in sleep–wake consolidating monkeys
Authors: Zeitzer Jamie M. , Buckmaster Christine L. , Lyons and David M. , Mignot Emmanuel
Published: April 2004

The hypocretin system is involved in the integration of hypothalamic functions with sleep and wake. Hypocretin‐1 release peaks at the end of the active period in both diurnal and nocturnal species. A role for hypocretin‐1 in the generation of locomotor activity has been suggested by electrophysiological and neurochemical studies in rodents, dogs and cats. These species, however, do not consolidate wake into a single, daily bout and manipulations of locomotion elicit changes in wakefulness, making it difficult to parse the relative contribution of these two factors. We have examined the relationship between locomotion and hypocretin‐1 in a wake‐consolidating animal, the squirrel monkey (Saimiri sciureus). Strikingly, we found that restricting locomotion to 17% of usual activity had no significant effect on the normal diurnal rise in cerebrospinal fluid (CSF) hypocretin‐1, despite an associated increase in CSF cortisol. Increasing locomotion to greater than baseline activity did not significantly increase CSF hypocretin‐1 concentrations, but did appear to have a positive modulatory effect on CSF hypocretin‐1. In this wake‐consolidating animal, locomotion is not necessary for CSF hypocretin‐1 to increase throughout the daytime, but high levels of locomotion are likely to provide a small positive feedback onto the hypocretin system.
Density‐dependent changes of the pore properties of the P2X2 receptor channel
Authors: Fujiwara Yuichiro , Kubo Yoshihiro
Published: April 2004

Ligand‐gated ion channels underlie and play important roles in synaptic transmission, and it is generally accepted that the ion channel pores have a rigid structure that enables strict regulation of ion permeation. One exception is the P2X ATP‐gated channel. After application of ATP, the ion selectivity of the P2X2 channel time‐dependently changes, i.e. permeability to large cations gradually increases, and there is significant cell‐to‐cell variation in the intensity of inward rectification. Here we show P2X2 channel properties are correlated with the expression level: increasing P2X2 expression level in oocytes increases permeability to large cations, decreases inward rectification and increases ligand sensitivity. We also observed that the inward rectification changed in a dose‐dependent manner, i.e. when low concentration of ATP was applied to an oocyte with a high expression level, the intensity of inward rectification of the evoked current was weak. Taken together, these results show that the pore properties of P2X2 channel are not static but change dynamically depending on the open channel density. Furthermore, we identified by mutagenesis study that Ile328 located at the outer mouth of the pore is critical for the density‐dependent changes of P2X2. Our findings suggest synaptic transmission can be modulated by the local density‐dependent changes of channel properties caused, for example, by the presence of clustering molecules.
Novel KChIP2 isoforms increase functional diversity of transient outward potassium currents
Authors: Decher Niels , Barth Andreas S. , Gonzalez Teresa , Steinmeyer Klaus , Sanguinetti Michael C.
Published: April 2004

Kv4.3 channels conduct transient outward K+ currents in the human heart and brain where they mediate the early phase of action potential repolarization. KChIP2 proteins are members of a new class of calcium sensors that modulate the surface expression and biophysical properties of Kv4 K+ channels. Here we describe three novel isoforms of KChIP2 with an alternatively spliced C‐terminus (KChIP2e, KChIP2f) or N‐terminus (KChIP2g). KChIP2e and KChIP2f are expressed in the human atrium, whereas KChIP2g is predominantly expressed in the brain. The KChIP2 isoforms were coexpressed with Kv4.3 channels in Xenopus oocytes and currents recorded with two‐microelectrode voltage‐clamp techniques. KChIP2e caused a reduction in current amplitude, an acceleration of inactivation and a slowing of the recovery from inactivation of Kv4.3 currents. KChIP2f increased the current amplitude and slowed the rate of inactivation, but did not alter the recovery from inactivation or the voltage of half‐maximal inactivation of Kv4.3 channels. KChIP2g increased current amplitudes, slowed the rate of inactivation and shifted the voltage of half‐maximal inactivation to more negative potentials. The biophysical changes induced by these alternatively spliced KChIP2 proteins differ markedly from previously described KChIP2 proteins and would be expected to increase the diversity of native transient outward K+ currents.
In vivo and in vitro studies onAnaplasma phagocytophiluminfection of the myeloid cells of a patient with chronic myelogenous leukaemia and human granulocytic ehrlichiosis
Authors: Bayard-Mc Neeley M , Bansal A , Chowdhury I , Girao G , Small C B , Seiter K , Nelson J , Liveris D , Schwartz I , Mc Neeley D F , Wormser G P , Aguero-Rosenfeld M E
Published: April 2004

Aims:The occurrence of human granulocytic ehrlichiosis (HGE) in a patient with chronic myelogenous leukaemia (CML) provided an opportunity to study whetherAnaplasma phagocytophilum, the aetiological agent of HGE, infects mature or immature cells, both in vivo and in vitro.

Methods:Diagnosis of HGE was confirmed by culture, polymerase chain reaction (PCR), detection of intragranulocytic inclusions, and serology. The infection rates of different myelogenous stages of granulocytic differentiation were determined by microscopy.Anaplasma phagocytophiluminfection of the bone marrow was analysed by PCR, culture, and microscopy. In addition, the in vitro growth ofA phagocytophilumin the patient’s granulocytes and in HL-60 cells (a promyelocytic leukaemia cell line) was compared.

Results:Pretreatment blood smears showed that mature granulocytic cells had a higher infection rate withA phagocytophilumthan did immature cells. In the original inoculation of the patient’s cells into HL-60 cells to isolateA phagocytophilum, the bacterium grew faster in the patient’s leukaemic cells than in HL-60 cells.Anaplasma phagocytophiluminclusions were rarely seen in bone marrow granulocytes and PCR was negative. In vitro, twoA phagocytophilumisolates grew faster in the patient’s granulocytes than in HL-60 cells.

Conclusions:The superior growth in CML cells compared with HL-60 cells suggests thatA phagocytophilumpreferentially infects mature granulocytes. The higher infection rate of the patient’s mature versus immature granulocytes before treatment and the minimal level of infection of the patient’s bone marrow support this. It is possible that the primary site of infection in HGE is the peripheral mature granulocytic population.
A patient with a VEGF and endostatin producing gastrointestinal autonomic nerve tumour
Authors: Hansma A H G , van Hensbergen Y , Kuenen B C , van Diest P J , Hanemaaijer R , Meijer S , Pinedo H M , Hoekman K
Published: April 2004

Tumour associated neovascularisation has been characterised as chaotic and insufficient. This report details the results of the analysis of angiogenic factors in tumour cyst fluid, pleural fluid, and blood from a patient with a gastrointestinal autonomic nerve tumour. The tumour produced vascular endothelial growth factor and endostatin in large quantities, which may explain the dysfunctional angiogenesis and tendency to bleeding seen in this tumour type.