bluuebunny/crossref_metadata_2025 huggingface dataset:
Hypervalent iodine in synthesis 85: An efficient method for the synthesis of N‐arylbenzimidazoles by the coppercatalyzed N‐arylation of benzimidazole with diaryliodonium salts
Authors: Zhou Tao , Chen Zhen‐Chu
Published: November 2002

N‐arylbenzimidazoles were prepared in moderate yields by copper‐catalyzed N‐arylation of benzimidazole with diaryliodonium salts. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:617–619, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10043
Synthesis and fragmentation of new 2‐phosphabicyclo[2.2.2]octene 2‐oxides
Authors: Keglevich György , Szelke Helga , Tamás Annamária , Harmat Veronika , Ludányi Krisztina , Vaskó Ágnes Gyöngyvér , Tőke László
Published: November 2002

The substitution pattern of the 2‐phosphabicyclo[2.2.2]octene framework and the skeleton itself were varied to obtain new cycloadducts usable in phosphorylations and to study their ability to undergo fragmentation. Thus, an N‐methyl and several P‐trialkylphenyl derivatives (7 and 9, respectively) were synthesized, together with two diaza species (8) whose stereostructure was evaluated by single crystal X‐ray analysis. Mechanistic studies on the UV light‐mediated photolysis of the P‐aryl phosphabicyclooctenes (9) in the presence of methanol supports the suggestion of a novel addition–elimination reaction path. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:626–632, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10052
Synthesis of 4‐phosphonyl‐1,3‐dithioles and 1,3‐dithiolanes via the Bu3P‐CS2 adduct
Authors: Xu Cheng‐Fu , Liu Yu‐Xiu , Wang Wen‐Hu , Cao Ru‐Zhen , Liu Lun‐Zu
Published: November 2002

New one‐pot syntheses of 2‐arylidene‐4‐phosphonyl‐1,3‐dithioles or 1,3‐dithiolanes were realized by reaction of the tributylphosphine‐carbon disulfide adduct with phosphonyl alkynes or phosphonyl alkenes and aldehydes in moderate yields. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:633–637, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10053
Synthesis, characterization, and biological studies of tri‐ and diorganotin(IV) complexes with 2′,4′‐difluoro‐4‐hydroxy‐[1,1′]‐biphenyle‐3‐carbolic acid: Crystal structure of [(CH3)3Sn(C13H7O3F2)]
Authors: Ahmad Fiaz , Ali Saqib , Parvez Masood , Munir Arshad , Mazhar M. , Khan Khalid M. , Shah Tasadaq Ali
Published: November 2002

Eight tri‐ and diorganotin(IV) carboxylates with general formulae R3SnL and R2SnL2 (where R = CH3, n‐C4H9, C6H5, C7H7, and L = 2′,4′‐difluoro‐4‐hydroxy‐[1,1′]‐biphenyl‐3‐carboxylic acid) were synthesized and characterized by UV–vis, IR, conductance, multinuclear (1H, 13C, and 119Sn) NMR spectroscopy, and mass spectrometry. The crystal structure of [(CH3)3Sn(C13H7O3F2)] indicates that the tin atom in the asymmetric unit exists in a trigonal bipyramidal geometry having a space group Pbca with an orthorhombic crystal system. These complexes were also screened for their antibacterial and antifungal activities. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:638–649, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10057
Synthesis of vinyl pyrophosphonate analogues of farnesyl pyrophosphate: New potential inhibitors of farnesyl protein transferase
Authors: Zgani Ibrahim , Menut Chantal , Montéro Jean Louis
Published: November 2002

The synthesis of new bioisosteric analogues of farnesyl pyrophosphate where a vinyl pyrophosphonate replaced the pyrophosphate moiety is described. These compounds have been prepared using a Horner–Wadsworth–Emmons procedure and a modified Michelson reaction. They have been evaluated for the inhibition of farnesyl protein transferase. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:654–661, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10081
1,3‐Dipolar cycloaddition of dipolar reagents to bis(styryl) sulfones
Authors: Padmavathi V. , Reddy K. Venugopal , Balaiah A. , Reddy T. V. Ramana , Reddy D. Bhaskar
Published: November 2002

Sulfonyl bis pyrazolines and isoxazolines were prepared by 1,3‐dipolar cycloaddition of nitrile imines and nitrile oxides to E,E‐bis(styryl) sulfones. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:677–682, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10087
Protection against acetaminophen hepatotoxicity by clofibrate pretreatment: Role of catalase induction
Authors: Chen Chuan , Hennig Gayle E. , Whiteley Herbert E. , Manautou José E.
Published: November 2002

Mice pretreated with the peroxisome proliferator clofibrate (CFB) are highly resistant to acetaminophen (APAP)‐induced hepatotoxicity. The objective of the present study was to investigate whether the increase in hepatic catalase activity following CFB pretreatment plays a role in this hepatoprotection. An irreversible inhibitor, 3‐amino‐1,2,4‐triazole (3‐AT), was used to modulate catalase activity. Hepatic catalase activity in mice pretreated with CFB (500 mg/kg, i.p., for 10 days) was significantly inhibited by 3‐AT (100 or 500 mg/kg, i.p.). In addition, the lower dose of 3‐AT (100 mg/kg) had minimal effect on biliary and urinary excretion of APAP metabolites generated from a nontoxic dose, suggesting that APAP metabolism was not modulated by this dose of 3‐AT. The mortality rate of corn‐oil‐pretreated mice challenged with APAP (800 mg/kg, p.o.) was significantly increased by 3‐AT (100 mg/kg, i.p.) given 1 h before APAP. As expected, CFB pretreatment conferred full protection against APAP‐induced hepatotoxicity. The same 3‐AT treatment, however, did not abolish hepatoprotection in CFB‐pretreated mice, despite the marked inhibition of hepatic catalase activity. In conclusion, these results indicate that elevated catalase activity in mice exposed to CFB does not appear to mediate the hepatoprotection, suggesting that other cellular defense mechanisms are involved. © 2002 Wiley Periodicals, Inc. J Biochem Mol Toxicol 16:227–234, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10043
Protective effect of arabic gum against cardiotoxicity induced by doxorubicin in mice: A possible mechanism of protection
Authors: Abd‐Allah Adel RA , Al‐Majed Abdulhakeem A. , Mostafa Adel M. , Al‐Shabanah Othman A. , Din Ayman Gamal El , Nagi Mahmoud N.
Published: November 2002

Arabic gum (AG) is a naturally occurring compound that has been proposed to posses potent antioxidant activity. In this study, the possible effects whereby AG could protect against cardiotoxicity induced by doxorubicin (DOX) in mice were carried out. Administration of single dose of DOX (15 mg/kg, i.p.) induced cardiotoxicity 72 h, manifested biochemically by a significant elevation of serum creatine kinase (CK) (EC 2.7.3.2). In addition, cardiotoxicity was further confirmed by the significant increase in lipid peroxides measured as malondialdehyde (MDA). Administration of AG (25 g/kg) orally for 5 days before and 72 h after DOX injection produced a significant protection against cardiotoxicity induced by DOX. This was evidenced by significant reductions in serum CK and cardiac lipid peroxides. The effect of AG was examined on the superoxide anion radical generated by enzymatic and nonenzymatic methods. The results indicate that AG is a potent superoxide scavenger. The superoxide scavenging effect of AG may explain, at least in part, the protective effect of AG against cardiotoxicity induced by DOX. © 2002 Wiley Periodicals, Inc. J Biochem Mol Toxicol 16:254–259, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10046
Comparison of the characteristic of estrogenic action patterns of β‐HCH and heregulin β1 in MCF‐7 human breast cancer cells
Authors: Hatakeyama Mariko , Zou Enmin , Matsumura Fumio
Published: November 2002

In this study, we compared the estrogenic action pattern of β‐HCH to another ErbB2 activating agent, heregulin β1 (HRG), along with 17β‐estradiol and epidermal growth factor, to understand the similarities and differences of their action mechanisms. Not surprisingly, most of the initial test results indicated that the two agents, β‐HCH and HRG, are remarkably similar in several estrogenicity tests. However, in‐depth biochemical studies revealed that there are some distinct differences between these two compounds in affecting ErbB2 and ErbB3 at early stages of their action. Immunocoprecipitation and Western blot studies indicated that β‐HCH mainly promotes dimerization of ErbB2 and ErbB3 at early time points, whereas HRG causes their dimerization with a rapid and significant rise in their tyrosine phosphorylation levels. These results indicate that, while both β‐HCH and HRG act through ErbB2, their initial actions differ. To understand the long‐term consequence of such differential actions of these two agents, we tested the effect of a number of standard pathway specific inhibitors on their actions to induce foci formation after 2 weeks of exposure. The most conspicuous difference between β‐HCH and HRG in MCF‐7 foci formation test was their response to 4‐hydroxytamoxifen and LY294002, a PI3K inhibitor, i.e., the action of β‐HCH was inhibited by 4‐hydroxytamoxifen but stimulated by LY294002, whereas that of heregulin was suppressed by LY294002 but stimulated by 4‐hydroxytamoxifen. It appears, therefore, that the action of the latter relies more heavily on the PI3K route as compared to that of the former which has been shown to mainly act through p42/44 MAPK. These differences may account for their differential sensitivities to 4‐hydroxytamoxifen. © 2002 Wiley Periodicals, Inc. J Biochem Mol Toxicol 16:209–219, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10047
Phenotypic rescue after adeno‐associated virus‐mediated delivery of 4‐sulfatase to the retinal pigment epithelium of feline mucopolysaccharidosis VI
Authors: Ho Thucanh T. , Maguire Albert M. , Aguirre Gustavo D. , Surace Enrico M. , Anand Vibha , Zeng Yong , Salvetti Anna , Hopwood John J. , Haskins Mark E. , Bennett Jean
Published: November 2002

Background

Mucopolysaccharidosis VI (MPS VI), due to recessively inherited 4‐sulfatase (4S) deficiency, results in lysosomal storage of dermatan sulfate in numerous tissues. Retinal involvement is limited to the retinal pigment epithelium (RPE). This study aimed to determine whether recombinant adeno‐associated virus (AAV)‐mediated delivery of 4S would reverse the RPE pathology seen in MPS VI cats.

Methods

AAV.f4S, containing the feline 4S cDNA, was delivered unilaterally to eyes of affected cats by subretinal or intravitreal injection. Contralateral eyes received AAV with the green fluorescent protein (GFP) reporter gene as control. At 2–11 months post‐injection, the cats were sacrificed and the treatment effects were evaluated histologically.

Results

By ophthalmoscopy and histological analyses, GFP was evident as early as 4 weeks and persisted through the latest time point (11 months). Untreated and AAV.GFP‐treated diseased retinas contained massively hypertrophied RPE cells secondary to accumulation of dilated lysosomal inclusions containing dermatan sulfate. MPS VI eyes treated subretinally with AAV.f4S had minimal RPE cell inclusions and, consequently, were not hypertrophied.

Conclusions

AAV‐mediated subretinal delivery of f4S provided correction of the disease phenotype in RPE cells of feline MPS VI, supporting the utility of AAV as a vector for the treatment of RPE‐specific as well as lysosomal storage diseases. Copyright © 2002 John Wiley & Sons, Ltd.
Polybrene and interleukin‐4: two opposing factors for retroviral transduction of bone‐marrow‐derived dendritic cells
Authors: Fresnay Stéphanie , Chalmers David E. , Ferrand Christophe , Colombain Christine , Newton Isobel , Yerly‐Motta Véronique , Lienard Agnès , Darodes de Tailly Patrick , Hervé Patrick , Tiberghien Pierre , Saas Philippe
Published: November 2002

Background

Gene transfer using retroviral transduction offers the advantage of long‐term transgene expression in developing strategies that use dendritic cells (DCs) for immunotherapy. The goal of this study was to infect DCs in an immature state in order to take advantage of their proliferating and tolerogenic potential.

Methods

Immature DCs were generated from murine bone marrow (BM) using either GM‐CSF alone or GM‐CSF plus IL‐4. The cells were transduced directly with retroviral supernatants or by co‐culture with the GP + E‐86 retroviral packaging cell line in the presence of two different cationic polymers: polybrene and protamine sulfate. Phenotypic and functional characterization of the transduced cells were then performed.

Results

Our results show a low efficiency of retroviral infection of DCs in the presence of polybrene. This cationic polymer was found to be directly cytotoxic to murine DCs and thus favored the growth of contaminating macrophages. This effect was not observed using protamine sulfate. Furthermore, stimulation by IL‐4 early in the culture increased DC differentiation, proliferation and transduction. However, we found that DCs generated in GM‐CSF plus IL‐4 presented a more mature phenotype with an enhanced allogeneic stimulating activity. Finally, we showed that DCs themselves down‐regulated transgene expression in the co‐cultured packaging cell line in a promoter‐dependent manner.

Conclusions

We have defined optimal conditions to generate and transduce murine BM‐derived DCs. This included: the use of protamine sulfate during exposure to retroviral infectious supernatant and the addition of IL‐4 at an early stage of the culture. Nevertheless, this cytokine also induced DC maturation. These findings have potential implications in experimental gene therapy. Copyright © 2002 John Wiley & Sons, Ltd.
Visual framework for development and use of constitutive models
Authors: M. A. Hashash Youssef , C. Wotring Donald , I‐Chiang Yao John , Lee Jung‐Suk , Fu Qingwei
Published: November 2002

Advanced constitutive relations are used in geotechnical engineering to capture measured soil and rock behaviour in the laboratory, and in numerical models to represent the material response. These constitutive relations have traditionally been difficult to use, understand, and develop except by a limited number of specialists. This paper describes a framework for transforming the representation of constitutive relations, as well as stress and strain quantities from a series of mathematical equations and matrix quantities to multidimensional geometric/visual objects in a dynamic interactive colour‐rich display environment. The paper proposes a shift in current approaches to the development of constitutive equations and their use in numerical simulations by taking advantage of rapid advancements in information technology and computer graphics. A novel interactive visualization development and learning environment for material constitutive relations referred to as VizCoRe is presented. Visualization examples of two constitutive relations, the linear elastic with von Mises failure criteria and the Modified Cam Clay (MCC) are shown. These include two‐ and three‐dimensional renderings of stress states and paths and yield and failure surfaces. In addition, the environment allows for the visualization of the implicit integration algorithm used for the numerical integration of both constitutive models. Copyright © 2002 John Wiley & Sons, Ltd.
An algebraic preconditioning method for M‐matrices: linear versus non‐linear multilevel iteration
Authors: Kraus J. K.
Published: November 2002

In a recent work, the author introduced a robust multilevel incomplete factorization algorithm using spanning trees of matrix graphs (Proceedings of the 1999 International Conference on Preconditioning Techniques for Large Sparse Matrix Problems in Industrial Applications, Hubert H. Humphrey Center, University of Minnesota, 1999, 251–257). Based on this idea linear and non‐linear algebraic multilevel iteration (AMLI) methods are investigated in the present paper.

In both cases, the preconditioner is constructed recursively from the coarsest to finer and finer levels. The considered W‐cycles only need diagonal solvers on all levels and additionally evaluate a second‐degree matrix polynomial (linear case), or, perform ν inner GCG‐type iterations (non‐linear case) on every other level. This involves the same type of preconditioner for the corresponding Schur complement. The non‐linear variant has the additional benefit of being free from any method parameters to be estimated. Based on the same type of approximation property similar convergence rates are obtained for linear and non‐linear AMLI, even for a very small number ν of inner iterations, e.g. ν =2,3. The presented methods are robust with respect to anisotropy and discontinuities in the coefficients of the PDEs and can also be applied to unstructured‐grid problems. Copyright © 2002 John Wiley & Sons, Ltd.
An HPLC method for the direct assay of the serotonin precursor, 5‐hydroxytrophan, in seeds of Griffonia simplicifolia
Authors: Lemaire Peter A. , Adosraku Reimmel K.
Published: November 2002

5‐Hydroxytryptophan (1) is a naturally occurring amino acid found in significant levels in seeds of Griffonia simplicifolia and used in the treatment of the numerous effects of serotonin deficiency syndrome. An HPLC method has been developed for the direct assay of 1 in seeds of G. simplicifolia which overcomes the problems associated with previous techniques. By optimising the solvent extraction procedures and the HPLC conditions, levels of 1 could be estimated following a single‐step seed extraction. The chromatographic conditions, solvent system and the extraction technique developed make this method relatively simple, fast and efficient. Using the described methods, the highest ever levels of 1 (namely, 20.83% on a fresh weight basis) have been determined in seeds of G. simplicifolia obtained in Ghana. Copyright © 2002 John Wiley & Sons, Ltd.
Anthocyanin composition of the fruit of Coriaria myrtifolia L.
Authors: Escribano‐Bailón María Teresa , Santos‐Buelga Celestino , Alonso Gonzalo L. , Salinas María Rosario
Published: November 2002

The anthocyanin composition of the fruit of Coriaria myrtifolia L. and the changes which occur during ripening were studied using HPLC‐PAD and LC‐MS. Ten anthocyanins were detected and identified by their absorption and mass spectra as the 3‐glucoside and 3‐galactoside derivatives of delphinidin, cyanidin, petunidin, peonidin and malvidin. Fruit ripening was accompanied by substantial changes in the anthocyanin profile, with methoxylated anthocyanins, i.e. malvidin and peonidin, predominating in the final stages of ripening, and the trihydroxylated anthocyanin, delphinidin, during the earlier stages. Furthermore, galactoside derivatives were more abundant than glucosides in the ripe fruit. At full maturity, the fruits of C. myrtifolia were very rich in anthocyanins with a content of 10.7% (on a dry weight basis), a level which is higher than that found in most fruits usually considered to be anthocyanin‐rich. The ability to grow C. myrtifolia in damaged and nitrogen poor soils, together with the possibility of using this plant for the extraction of anthocyanin, makes it ideal for consolidating soils and repopulating semi‐desert or fire‐damaged areas. Copyright © 2002 John Wiley & Sons, Ltd.
Direct determination of alkaloid contents in Fumaria species by GC‐MS
Authors: Suau R. , Cabezudo B. , Rico R. , Nájera F. , López‐Romero J. M.
Published: November 2002

The isoquinoline alkaloids protopine, cryptopine, sinactine, stylopine, bicuculline, adlumine, parfumine, fumariline, fumarophycine, fumaritine, dihydrofumariline, parfumidine and dihydrosanguinarine have been determined and identified by gas chromatography–mass spectrometry in Fumaria agraria, F. bastardii, F. capreolata, F. sepium, F. densiflora, F. faurei, F. officinalis subsp. officinalis, F. parviflora, F. petteri subsp. calcarata and F. macrosepala. The chemotaxonomic significance of the results is discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Determination of the diterpenoid, kaurenoic acid, in Annona glabra by HPLC
Authors: Oliveira Brás H. , Sant'Ana Antônio Euzébio G. , Bastos Denise Z. L.
Published: November 2002

The isolation of ent‐kaur‐16‐en‐19‐oic acid (1) from the leaves and bark of Annona glabra and its determination by reversed‐phase HPLC with a photodiode array detector is described. The results indicate that 1 accumulates in the bark of the plant with only very low concentrations in the leaves. Levels of 1 varied throughout the year being highest for bark and leaves in the autumn (5.29 ± 0.23 and 0.27 ± 0.01 mg/g dry weight, respectively) and lowest in the spring for bark and in the winter for leaves (4.00 ± 0.25 and 0.11 ± 0.01 mg/g dry weight, respectively). Copyright © 2002 John Wiley & Sons, Ltd.
Investigation of Bradykinin metabolism in human and rat plasma in the presence of the dual ace/NEP inhibitors GW660511X and omapatrilat
Authors: Heudi Olivier , Ramirez‐Molina Cesar , Marshall Peter , Amour Augustin , Peace Simon , McKeown Stephen , Abou‐Shakra Fadi
Published: November 2002

Several studies have suggested that the accumulation of bradykinin, or that of one its metabolites BK1–8, is involved in the occurrence of side effects such as AE associated with the use of various ACEi. In this work a novel approach combining HPLC‐UV on‐line with oaTOF‐MS and ICPMS was applied to investigate in human and rat plasma the metabolism of labelled BK (79/81Br‐Phe5) BrBK in the presence of two new dual ACE/NEP inhibitors (GW660511X and omapatrilat) currently under clinical trial.

In human plasma the BrBK half‐life values in the absence or in the presence of GW660511X (3.8 µM) or omapatrilat (32 nM) were 38.7 ± 2.4, 51.2 ± 4.7 and 114.7 ± 9.3 min, respectively and BrBK was degraded into BrBK1–8, BrBK1–7, BrBK1–5 and Br‐Phe5. In the presence of inhibitors, however, the levels of these resultant metabolites were different. Unlike GW660511X, omapatrilat abolished the production of BrBK1–5 and BrBK1–7, suggesting a better ACE inhibition effect over GW660511X as no NEP activity was found. In addition the production of BrBK1–8 was enhanced in the presence of these inhibitors with a greater accumulation being observed with omapatrilat. The production of Br‐Phe5 was reduced with GW660511X while no significant change was observed with omapatrilat after 4 h of incubation. In rat plasma the BrBK half‐life values in the absence or in the presence of GW660511X (530 nM) or omapatrilat (50 nM) were 9.31 ± 1.7, 22.06 ± 3.1 and 25.3 ± 1.7 min, respectively and BrBK was degraded into BrBK1–8, BrBK1–7, BrBK1–5 and Br‐Phe5 plus BrBK2–9, BrBK4–8 and BrBK2–8 metabolites not found in human plasma. GW660511X and omapatrilat reduced the production of BrBK1–5 and BrBK1–7 with more effect being observed with omapatrilat. GW660511X and omapatrilat increased the production of both BrBK1–8 and Br‐Phe5 but not that of BrBK4–8 and BrBK2–8.

This study shows that the potency of GW660511X in comparison with omapatrilat is more than 100‐fold lower in human, but less than 10‐fold lower in rat plasma, suggesting that rat may not be a suitable in vivo model for the evaluation of ACE/NEP inhibition in relation to effects in humans. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Post‐synthesis incorporation of a lipidic side chain into a peptide on solid support
Authors: Douat Céline , Heitz Annie , Paris Marielle , Martinez Jean , Fehrentz Jean‐Alain
Published: November 2002

A new strategy for the synthesis of lipopeptides has been developed. Using Weinreb (N‐methoxy, N‐methyl) amide as an aldehyde function precursor on the side chains of Asp or Glu residues, this new strategy avoids the synthesis of a lipidic amino acid residue before its incorporation in the peptide sequence. The aldehyde generated on the solid support can react with ylides leading to unsaturated or saturated side chains or with various nucleophiles to yield non‐coded amino acid residues incorporated into the sequence. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
SPPS of protected peptidyl aminoalkyl amides
Authors: Karavoltsos Manolis , Mourtas Spyros , Gatos Dimitrios , Barlos Kleomenis
Published: November 2002

Monophthaloyl diamines derived from naturally occurring amino acids were attached through their free amino functions to resins of the trityl type. The phthaloyl groups were removed by hydrazinolysis, and peptide chains were assembled using Fmoc/tBu‐amino acids on the liberated amino functions. The peptidyl aminoalkyl amides obtained were cleaved from the resins by mild acidolysis, with the tBu‐side chain protection remaining intact. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
NMR studies on Ni(II) induced cyclization of a histidine‐tagged peptide
Authors: Spiga Ottavia , Bernini Andrea , Scarselli Maria , Ciutti Arianna , Giovannoni Leonardo , Laschi Franco , Bracci Luisa , Niccolai Neri
Published: November 2002

A linear decapeptide, HGASYQDLGH, was synthesized and used as a model to evaluate the effect of nickel addition upon non‐covalent backbone cyclization. The NMR data, obtained for the peptide in the presence of the metal ion, support the existence of predominant folded structures in solution, where the two His residues are maintained close to each other. These results suggest that insertion of even a single His residue at each peptide terminus can be used efficiently to reduce peptide flexibility without any backbone modification. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
A Class of Transpose Jacobian‐based NPID Regulators for Robot Manipulators with an Uncertain Kinematics
Authors: Huang C. Q. , Wang X. G. , Wang Z. G.
Published: November 2002

Transpose Jacobian‐based controllers present an attractive approach to
robot set‐point control in Cartesian space that derive the end‐effector posture
to a specified desired position and orientation with neither solving the inverse
kinematics nor computing the inverse Jacobian. By a Lyapunov function with
virtual artificial potential energy, a class of complete transpose Jacobian‐based
Nonlinear proportional‐integral‐derivative regulators is proposed in this
paper for robot manipulators with uncertain kinematics on the basis of the
set of all continuous differentiable increasing functions. It shows globally
asymptotic stability for the result closed‐loop system on the condition of
suitable feedback gains and suitable parameter selection for the corresponding
function set as well as artificial potential function, and only upper bound
on Jacobian matrix error and Cartesian dynamics parameters are needed. The
existing linear PID (LPID) regulators are the special cases of it. Nevertheless,
in the case of LPID regulators, only locally asymptotic stability is guaranteed
if the corresponding conditions are satisfied. Simulations demonstrate the
result and robustness of transpose Jacobian‐based NPID regulators. ©
2002 Wiley Periodicals, Inc.
Structural Properties of Inertia Matrix and Gravity Vector of Dynamics of Rigid Manipulators
Authors: Ignacy
Published: November 2002

In this paper, with the use of Euler‐Lagrange formalism, it has been proven
which joint variables can influence entries of the inertia matrix and the
gravity vector of dynamics of a manipulator relative to the kinematic structure
of the manipulator. Some formulas, alternative to well‐known ones, are presented
that allow us to compute the inertia matrix and the gravity vector without
using a trace operator. These formulas are computationally inexpensive and
provide an inspiration for interesting interpretations. Complexity indices
are defined that are able to evaluate the complexity of dynamics of manipulators
based on their kinematics. A key role of the accumulated pseudoinertia matrix
of the manipulator has been shown. © 2002 Wiley Periodicals, Inc.
CAT4 (Cable Actuated Truss—4 Degrees of Freedom): A Novel 4 DOF Cable Actuated Parallel Manipulator
Authors: Kossowski Craig , Notash Leila
Published: November 2002

The CAT4 (Cable Actuated Truss—4 degrees of freedom) robot is a novel,
passively jointed, parallel robot utilizing six control cables for actuation.
The architecture has been under development at the Queen's University
Robotics Laboratory. The robot utilizes a passive jointed linkage with 18
revolute joints to constrain the end effector motion and provide the desired
structural stability, restricting the end effector to 3 translational degrees
of freedom (DOF) and 1 DOF for end effector pitch. This central mechanism
together with winched cable actuation gives a number of important benefits
for applications where the advantages of a parallel robot are required in
conjunction with light weight. Six electric motor driven winches control the
length of the cable actuators that extend from the top frame to points on
the end effector raft and jointed linkage to create a stiff, but lightweight,
actuated robot. Simulation work on the robot is presented giving the kinematics,
including a computational estimate of the workspace for a specific configuration.
Results of computational simulation of the motion of the manipulator and a
discussion of the advantages and potential difficulties are also presented.
© 2002 Wiley Periodicals, Inc.
Testing membership in parenthesis languages
Authors: Parnas Michal , Ron Dana , Rubinfeld Ronitt
Published: November 2002

We continue the investigation of properties defined by formal languages. This study was initiated by Alon et al. [1], who described an algorithm for testing properties defined by regular languages. Alon et al. also considered several context free languages, and in particular Dyck languages, which contain strings of properly balanced parentheses. They showed that the first Dyck language, which contains strings over a single type of pairs of parentheses, is testable in time independent of n, where n is the length of the input string. However, the second Dyck language, defined over two types of parentheses, requires Ω (log n) queries. Here we describe a sublinear‐time algorithm for testing all Dyck languages. Specifically, the running time of our algorithm is Õ(n2/3/ϵ3), where ϵ is the given distance parameter. Furthermore, we improve the lower bound for testing Dyck languages to \documentclass{article}\usepackage{amsfonts,amsmath}\pagestyle{empty}\begin{document}$\tilde{\Omega}$\end{document}(n1/11) for constant ϵ. We also describe a testing algorithm for the context free language LREV = {uurvvr : u, v ∈ Σ*}, where Σ is a fixed alphabet. The running time of our algorithm is
\documentclass{article} \usepackage{amsfonts,amsmath}\pagestyle{empty} \begin{document}$\tilde{O}(\sqrt{n/\epsilon}$ \end{document},
which almost matches the lower bound given by Alon et al. [1]. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 22: 98–138, 2003
How many random edges make a dense graph hamiltonian?
Authors: Bohman Tom , Frieze Alan , Martin Ryan
Published: November 2002

This paper investigates the number of random edges required to add to an arbitrary dense graph in order to make the resulting graph hamiltonian with high probability. Adding Θ(n) random edges is both necessary and sufficient to ensure this for all such dense graphs. If, however, the original graph contains no large independent set, then many fewer random edges are required. We prove a similar result for directed graphs. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 22: 33–42, 2003
RENEWAL CONVERGENCE RATES FOR DHR AND NWU LIFETIMES
Authors: Berenhaut Kenneth S. , Lund Robert
Published: November 2002

This article studies the geometric convergence rate of a discrete
renewal sequence with decreasing hazard rate or, more generally,
new worse than used lifetimes. Several variants of these structural
orderings are considered. The results are derived from power
series methods; roots of generating functions are the prominent
issue. Optimality of the rates are considered. Examples
demonstrating the utility of the results, as well as applications
to Markov chains, are presented.
THE DEFERRAL OPTION IN LONG-TERM-CARE INSURANCE
Authors: Frostig Esther , Kliger Doron , Levikson Benny
Published: November 2002

Long-term-care (LTC) insurance contracts provide the insured
with different benefits for several nursing care levels, for
a limited number of benefit eligibility periods. A common
assumption in pricing these LTC contracts is that the insured
will exercise the right to claim benefits as soon as the
eligibility conditions are satisfied. This assumption, however,
may contradict the insured's optimization, as it might
be worthwhile not to claim when in low care levels and, by doing
so, save the option of claiming higher (more expensive) care
levels in the future. We term this option of the insured as
the deferral option. The consequence of the traditional pricing
(i.e., of ignoring the deferral option) is unexpected losses
to the insurer. The factors affecting the deferral option's
value are the risk of death, the discount factor, the benefit
levels of the different care levels, and the transition
probabilities between the different care levels.
OPTIMAL MONETARY AND FISCAL POLICIES UNDER WAGE AND PRICE RIGIDITIES
Authors: Bénassy Jean-Pascal
Published: November 2002

We study a structural dynamic monetary economy submitted to technological, monetary, and real demand shocks, and investigate the nature of optimal monetary and fiscal policies under Walrasian or preset wages and prices. If prices and wages are Walrasian, then the optimal policies are both nonactivist and derive directly from Milton Friedman's prescriptions. If prices or wages are preset, however, optimal policies, and, notably, the fiscal part, become activist and countercyclical.
EDITOR'S INTRODUCTION
Authors: Salmon Mark
Published: November 2002

The papers collected in this issue are united in a common view that it is rational to recognize that we have a poor perception of the constraints we face when making economic decisions and hence we employ decision rules that are robust. Robustness can be interpreted in different ways but generally it implies that our decision rules should not depend critically on an exact description of these constraints but they should perform well over a prespecified range of potential variations in the assumed economic environment. So, we are interested in deriving optimal and hence rational decisions where our utility or loss function incorporates the need for robustness in the face of a misspecified model. This misspecification can involve placing simple bounds on deviations from the parameters we assume for a nominal model, or misspecified dynamics, neglected nonlinearities, time variation, or quite general arbitrary misspecification in the transfer function between the input uncertainties and the output variables in which we are ultimately interested.
Examining Individuals' Desire for Shorter Commute: The Case of Proximate Commuting
Authors: Rodríguez Daniel A
Published: November 2002

Much of the theoretical and empirical debate about transport and land-use planning has focused upon the strength and vitality of the connection between the two. Studies increasingly find that this connection is weakening and thus attempts to address urban transport problems with land-use policies are ineffective. The author introduces proximate commuting, a novel employer-based program that decreases urban commuting by providing marginal accessibility improvements to its participants. With the aid of a case study involving a commercial bank in the Western Detroit Metropolitan Area, the author examines individuals' motivations for participating in a proximate-commuting program. Results show that 25% of bank tellers surveyed state that they are willing to take advantage of this accessibility-improvement program. Estimation of a discrete-choice model reveals that gender; expected improvements in accessibility; and better job prospects are three key factors explaining individuals' stated willingness to proximate commute. To the extent that these results hold more generally, they underscore the usefulness of interventions that rely on marginal improvements of home-to-work accessibility. Furthermore, the case illustrates an innovative approach for addressing transport challenges that is both politically palatable and enhances individual choices.
Recipient iNOS but Not eNOS Deficiency Reduces Luminal Narrowing in Tracheal Allografts
Authors: Minamoto Kanji , Pinsky David J.
Published: November 2002

Chronic airway rejection is characterized by prolonged inflammation, epithelial damage, and eventual luminal obliterative bronchiolitis (OB). In cardiac allografts, the inducible nitric oxide synthase (iNOS) promotes acute rejection but paradoxically reduces neointimal formation, the hallmark of chronic rejection. The specific roles of NOS isoforms in modulating lymphocyte traffic and airway rejection are not known. Using a double lumen mouse tracheal transplant model, tracheal grafts from B10.A (allo) or C57BL/6J (iso) mice were transplanted into cyclosporine-treated wild-type (WT) iNOS−/− or endothelial NOS (eNOS)−/− recipients. OB was observed in WT tracheal allografts at 3 weeks (53 ± 2% luminal occlusion vs. 17 ± 1% for isografts, P < 0.05) with sites of obstructive lesion formation coinciding with areas of CD3+ CD8+ T cell–rich lymphocytic bronchitis. In contrast, allografts in iNOS−/− recipients exhibited reductions in local expression of proinflammatory chemokines and cytokines, graft T cell recruitment and apoptosis, and luminal obliteration (29 ± 2%, P < 0.05 vs. WT allografts). Recipient eNOS deficiency, however, suppressed neither chemokine expression, lymphocyte infiltration, nor airway occlusion (54 ± 2%). These data demonstrate that iNOS exacerbates luminal obliteration of airway allografts in contrast with the known suppression by iNOS of cardiac allograft vasculopathy. Because iNOS−/− airways transplanted into WT allograft hosts are not protected from rejection, these data suggest that iNOS expressed by graft-infiltrating leukocytes exerts the dominant influence on airway rejection.
Raf-1 Antagonizes Erythroid Differentiation by Restraining Caspase Activation
Authors: Kolbus Andrea , Pilat Sandra , Husak Zvenyslava , Deiner Eva Maria , Stengl Gabriele , Beug Hartmut , Baccarini Manuela
Published: November 2002

The Raf kinases are key signal transducers activated by mitogens or oncogenes. The best studied Raf isoform, Raf-1, was identified as an inhibitor of apoptosis by conventional and conditional gene ablation in mice. c-raf-1−/− embryos are growth retarded and anemic, and die at midgestation with anomalies in the placenta and fetal liver. Here, we show that Raf-1–deficient primary erythroblasts cannot be expanded in culture due to their accelerated differentiation into mature erythrocytes. In addition, Raf-1 expression is down-regulated in differentiating wild-type cells, whereas overexpression of activated Raf-1 delays differentiation. As recently described for human erythroid precursors, we find that caspase activation is necessary for the differentiation of murine fetal liver erythroblasts. Differentiation-associated caspase activation is accelerated in erythroid progenitors lacking Raf-1 and delayed by overexpression of the activated kinase. These results reveal an essential function of Raf-1 in erythropoiesis and demonstrate that the ability of Raf-1 to restrict caspase activation is biologically relevant in a context distinct from apoptosis.
Age at First Viral Infection Determines the Pattern of T Cell–mediated Disease during Reinfection in Adulthood
Authors: Culley Fiona J. , Pollott Joanne , Openshaw Peter J.M.
Published: November 2002

Infants experiencing severe respiratory syncytial virus (RSV) bronchiolitis have an increased frequency of wheeze and asthma in later childhood. Since most severe RSV infections occur between the 8th and 24th postnatal week, we examined whether age at first infection determines the balance of cytokine production and lung pathology during subsequent rechallenge. Primary RSV infection in newborn mice followed the same viral kinetics as in adults but was associated with reduced and delayed IFN-γ responses. To study rechallenge, mice were infected at 1 day or 1, 4, or 8 weeks of age and reinfected at 12 weeks. Neonatal priming produced more severe weight loss and increased inflammatory cell recruitment (including T helper 2 cells and eosinophils) during reinfection, whereas delayed priming led to enhanced interferon γ production and less severe disease during reinfection. These results show the crucial importance of age at first infection in determining the outcome of reinfection and suggest that the environment of the neonatal lung is a major determinant of cytokine production and disease patterns in later life. Thus, simply delaying RSV infection beyond infancy might reduce subsequent respiratory morbidity in later childhood.
In Vivo Activation of cAMP Signaling Induces Growth Arrest and Differentiation in Acute Promyelocytic Leukemia
Authors: Guillemin Marie-Claude , Raffoux Emmanuel , Vitoux Dominique , Kogan Scott , Soilihi Hassane , Lallemand-Breitenbach Valérie , Zhu Jun , Janin Anne , Daniel Marie-Thérèse , Gourmel Bernard , Degos Laurent , Dombret Hervé , Lanotte Michel , de Thé Hugues
Published: November 2002

Differentiation therapy for acute myeloid leukemia uses transcriptional modulators to reprogram cancer cells. The most relevant clinical example is acute promyelocytic leukemia (APL), which responds dramatically to either retinoic acid (RA) or arsenic trioxide (As2O3). In many myeloid leukemia cell lines, cyclic adenosine monophosphate (cAMP) triggers growth arrest, cell death, or differentiation, often in synergy with RA. Nevertheless, the toxicity of cAMP derivatives and lack of suitable models has hampered trials designed to assess the in vivo relevance of theses observations. We show that, in an APL cell line, cAMP analogs blocked cell growth and unraveled As2O3-triggered differentiation. Similarly, in RA-sensitive or RA-resistant mouse models of APL, continuous infusions of 8-chloro-cyclic adenosine monophosphate (8-Cl-cAMP) triggered major growth arrest, greatly enhanced both spontaneous and RA- or As2O3-induced differentiation and accelerated the restoration of normal hematopoiesis. Theophylline, a well-tolerated phosphodiesterase inhibitor which stabilizes endogenous cAMP, also impaired APL growth and enhanced spontaneous or As2O3-triggered cell differentiation in vivo. Accordingly, in an APL patient resistant to combined RA–As2O3 therapy, theophylline induced blast clearance and restored normal hematopoiesis. Taken together, these results demonstrate that in vivo activation of cAMP signaling contributes to APL clearance, independently of its RA-sensitivity, thus raising hopes that other myeloid leukemias may benefit from this therapeutic approach.
Cross-linking the B7 Family Molecule B7-DC Directly Activates Immune Functions of Dendritic Cells
Authors: Nguyen Loc T. , Radhakrishnan Suresh , Ciric Bogoljub , Tamada Koji , Shin Tahiro , Pardoll Drew M. , Chen Lieping , Rodriguez Moses , Pease Larry R.
Published: November 2002

B7-DC molecules are known to function as ligands on antigen-presenting cells (APCs), enhancing T cell activation. In this study, cross-linking B7-DC with the monoclonal antibody sHIgM12 directly potentiates dendritic cell (DC) function by enhancing DC presentation of major histocompatibility complex–peptide complexes, promoting DC survival; and increasing secretion of interleukin (IL)-12p70, a key T helper cell type 1 promoting cytokine. Furthermore, ex vivo treatment of DCs or systemic treatment of mice with sHIgM12 increases the number of transplanted DCs that reach draining lymph nodes and increases the ability of lymph node APCs to activate naive T cells. Systemic administration of the antibody has an equivalent effect on DCs transferred at a distant site. These findings implicate B7-DC expressed on DCs in bidirectional communication. In addition to the established costimulatory and inhibitory functions associated with B7-DC, this molecule can also function as a conduit for extracellular signals to DCs modifying DC functions.
Effects of hyperfine structure on the relaxation of alkali-metal resonance levels
Authors: E L Lewis  , C S Wheeler
Published: November 2002

The effects of nuclear spin on the observed relaxation constants of2P1/2,3/2alkali-metal resonance levels are calculated. While the primary interest is in obtaining correction factors for the Hanle effect measurements, the nuclear spin effects on experimental measurements by other techniques are also discussed and it is shown that some apparent discrepancies in the literature may be resolved. The experimental data for sodium and rubidium perturbed by the rare gases are discussed critically as examples of small and large fine structure respectively.
Solvability of linear systems of PDE’s with constant coefficients
Authors: Zhou Ding-Xuan
Published: November 2002

In this paper we investigate the solvability of linear systems of partial differential equations with constant coefficients in a field of positive characteristic. In particular, we prove that consistence and compatibility are equivalent, which answers a question of Ehrenpreis and extends a result of Jia. The problem of uniqueness is also considered.
Note on Heath-Brown’s estimate for Heilbronn’s exponential sum
Authors: Yu Hong
Published: November 2002

We show that
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper S Subscript h Baseline left-parenthesis a right-parenthesis equals sigma-summation Underscript n equals 1 Overscript p Endscripts e left-parenthesis StartFraction a n Superscript h p Baseline Over p squared EndFraction right-parenthesis much-less-than left-parenthesis h comma p minus 1 right-parenthesis p Superscript 11 slash 12">

S
h

(
a
)
=

∑

n
=
1

p

e
(

a

n

h
p

p
2

)
≪
(
h
,
p
−
1
)

p

11

/

12

S_h(a)=\sum ^p_{n=1}e(\frac {an^{hp}}{p^2})\ll (h,p-1)p^{11/12}

, which generalizes Heath-Brown’s estimate for Heilbronn’s exponential sum

S
1

(
a
)

S_1(a)

. We also give a simple proof of a crucial lemma in Heath-Brown’s work.
Cubic reciprocity and generalised Lucas-Lehmer tests for primality of 𝐴.3ⁿ±1
Authors: Berrizbeitia Pedro , Berry T.
Published: November 2002

Cubic reciprocity is used to derive primality tests analogous to the Lucas-Lehmer test for integers of the form

A

.3
n

±
1

A.3^n \pm 1

. The test for

A

.3
n

−
1

A.3^n-1

is a minor improvement on a test derived by Williams by other means; the test for

A

.3
n

+
1

A.3^n+1

seems to be new.
On the disjointness problem for Gaussian automorphisms
Authors: Lemańczyk M. , Parreau F.
Published: November 2002

If

T

σ
1

T_{\sigma _1}

,

T

σ
2

T_{\sigma _2}

are two Gaussian automorphisms, where

σ
1

\sigma _1

and

σ
2

\sigma _2

are concentrated on independent sets, then we have a dichotomy: either they are spectrally disjoint or they have a common factor. As an application, we construct non-rigid automorphisms which are spectrally determined.
On permutation representations of polyhedral groups
Authors: Sury B.
Published: November 2002

We answer affirmatively the following question of Derek Holt: Given integers

l
,
m
,
n
≥
2

l,m,n \geq 2

, can one, in a simple manner, find a finite set

Ω
\Omega

and permutations

a
,
b

a,b

such that

a
a

has order

l
l

,

b
b

has order

m
m

and

a
b

ab

has order

n
n

? The method of proof enables us to prove more general results (Theorems 2 and 3).
On the structure of periodic modules over tame algebras
Authors: Skowroński Andrzej
Published: November 2002

We describe the structure of stable tubes in the Auslander–Reiten quivers of tame algebras formed by indecomposable modules which do not lie on infinite short cycles. In particular, we prove that all algebras whose module categories have no infinite short cycles are of linear growth.
On equivariant slice knots
Authors: Cha Jae , Ko Ki
Published: November 2002

We suggest a method to detect that two periodic knots are not equivariantly concordant, using surgery on factor links. We construct examples which satisfy all known necessary conditions for equivariant slice knots— Naik’s and Choi-Ko-Song’s improvements of classical results on Seifert forms and Casson-Gordon invariants of slice knots — but are not equivariantly slice.