bluuebunny/crossref_metadata_2025 huggingface dataset:
Indian hedgehog gene transfer augments hematopoietic support of human stromal cells including NOD/SCID–ß2m–/– repopulating cells.
Authors: Kobune Masayoshi , Ito Yoshinori , Kawano Yutaka , Sasaki Katsunori , Uchida Hiroaki , Nakamura Kiminori , Dehari Hironari , Chiba Hiroki , Takimoto Rishu , Matsunaga Takuya , Terui Takeshi , Kato Junji , Niitsu Yoshiro , Hamada Hirofumi
Published: April 2004

Hematopoietic stem cells (HSCs) are a subset of bone marrow cells that are capable of self-renewal and of giving rise to all types of blood cells. However, the mechanisms involved in controlling the number and abilities of HSCs remain largely unknown. The Indian hedgehog (Ihh) signal has an essential role in inducing hematopoietic tissue during embryogenesis. We investigated the roles of the Ihh in coculture with CD34+ cells and human stromal cells. Ihh mRNA was expressed in primary and telomerized human (hTERT) stromal cells, and its receptor molecules were detected in CD34+ cells. Ihh gene transfer into hTERT stromal cells enhanced their hematopoietic supporting potential, which was elevated compared with control stromal cells, as indicated by the colony-forming units in culture (CFU-Cs) (26-fold ± 2-fold versus 59-fold ± 3-fold of the initial cell number; mixed colony-forming units [CFU-Mix's], 63-fold ± 37-fold versus 349-fold ± 116-fold). Engraftments of nonobese diabetic/severe combined immunodeficiency–ß2m–/– (NOD/SCID–ß2m–/–) repopulating cells (RCs) expanded on Ihh stromal cells were significantly higher compared with control coculture results, and engraftment was neutralized by addition of an antihedgehog antibody. Limiting dilution analysis indicated that NOD/SCID–ß2m–/– RCs proliferated efficiently on Ihh stromal cells, compared with control stromal cells. These results indicate that Ihh gene transfer could enhance the primitive hematopoietic support ability of human stromal cells.
Economy and culture are dead! Long live economy and culture!
Authors: Castree Noel
Published: April 2004

This essay critically evaluates the debate in human geography and cognate fields about economy-culture relationships. It takes issue with the terms of the debate, wherein different authors have sought to ground their claims about economy and culture with reference to supposed ‘ontological realities’. Building on the arguments of Don Mitchell (1995; 2000), I argue that economy and culture should be seen as two powerful ideas that help to create the realities they seem only to describe. Economy and culture cannot, I argue, be uncritically invoked by academic analysts as either objects of analysis or explanatory resources. Rather, we need to inquire into how the ideas of economy and culture are semantically ‘fixed’ and with reference to what ‘real-world’ phenomena. Taking the case of indigenous peoples' deployment of the idea of ‘cultural property’, I illustrate the kind of research agenda that follows from seeing ‘economy’ and ‘culture’ as two performative signifiers. I also challenge those involved in the economy-culture debate to take seriously their own role in sustaining, altering or eclipsing the various meanings and referents of these two powerful key words.
A Sense of Life: the future of industrial-style health care
Authors: Hunt Geoffrey
Published: April 2004

In this article I attempt to transcend the mainstream conception of health care ethics, including nursing ethics, by bringing into the foreground a tension between a sense of life and an industrial-bureaucratic style of health care, with its emphasis on the systematic and procedural work culture necessary for mass production. I use the concept of ‘a sense of life’ to draw attention to the wisdom, sensitivity and responsibility that is necessary for the authentic care of others to be given a chance in the development of modern health care. I emphasize the mindfulness that the professional requires for genuine care, and how the systematic organization of modern health care, on the whole, ignores, obstructs and even suppresses such mindfulness.
Sulfoximines: Synthesis and Catalytic Applications
Authors: Okamura Hiroaki , Bolm Carsten
Published: April 2004

Chiral sulfoximines have a stereogenic center at the sulfur atom and their use in asymmetric synthesis is well established. Recently, sulfoximines have been recognized as an interesting new class of chiral ligands, which can be applied in various asymmetric metal catalyses. This review summarizes the latest progress in synthetic methods towards sulfoximines and the application of chiral derivatives in catalytic asymmetric reactions.
Real Dimensions of the Drug Ions from Conductometric Studies of Drugs (Present as Salts) in Acetonitrile
Authors: Mandal R. , Gangopadhyay J. , Lahiri S. C.
Published: April 2004

The Λ0and association constants of salts of some widely used drugs (pharmacological agents) in acetonitrile have been determined. The division of Λ0into single ion values λ0+and λ0−has been made using λ0Na⁺and λ0Cl⁻values from the literature. The λ0+and λ0−values have been found to be considerable in acetonitrile. The results suggest that many of the drugs can be present both as dissociated ions as well as associated molecules which are capable of absorption, dissociation and conduction (of ionic forms) in the lipid layers at very low concentrations. The phenomenon of unsolvation has been utilized to calculate the real dimensions of the drug ions (cations or anions) which are difficult to calculate from bond distances due to their large size and coiled configuration in aqueous solutions.
Variational Approach to Electron Transfer in Bridged Diruthenium Complexes
Authors: Vollmer Elena , Kordel Mattias , Koslowski Thorsten
Published: April 2004

In this work, we address the energetics of electron transfer in bridged diruthenium complexes from a theoretical and numerical perspective. The electronic structure of the bridged complexes is described by a tight-binding Hamiltonian, which is extended by an on-site spin pairing energy. The coupling of the system to a polarizable solvent is taken into account by a nonretarded reaction field. The resulting nonlinear Hamiltonian is solved within the Hartree–Fock mean-field approximation, and the emerging potential energy surface is analysed using Marcus´ theory of electron transfer reactions. For the systems studied here, the charge transfer rate depends on the chemical nature of the bridge rather than the intermetal distance. We discuss the special nature of the Creutz–Taube cation, which is on the border of charge delocalization.
Indian Saints and Nation-States: Ignacio Manuel Altamirano’s Landscapes and Legends
Authors: Wright-Rios Edward
Published: April 2004

Analyzing the costumbrista sketches of Ignacio Manuel Altamirano as a single multi-faceted work, and comparing his treatment of popular Catholicism in different communities, this study represents a new reading of the author’s writings. It proposes that Altamirano’s juxtaposition of religion and modernity across urban-rural and ethnic continua reveals the author exploring the possibilities of Indian-centered nationalism rooted in what he describes as the innately American, independent spirit of rural indigenous Catholic practice. In short, camou- flaged in a traditional, eclectic genre, Altamirano identified the foundations of the national character in Indian popular religion long before twentieth-century indigenismo looked to contemporary Native American culture for inspiration.
Living with Dementia: Lay Definitions of Alzheimer's Disease among African American Caregivers and Sufferers
Authors: Belgrave Linda Liska , Allen‐Kelsey G. Janice , Smith Kenneth J. , Flores Maritza C.
Published: April 2004

While the medical world aggressively pursues scientific knowledge about Alzheimer's disease, sufferers and caregivers live with this ailment, not as patients, but as people going about their lives, needing and providing care. This article reports explanations of Alzheimer's from the perspectives of African American family caregivers and sufferers. Data were collected from thirty‐six families using participant observation and focus group interviews. Although caregivers sought and used medical expertise, their explanations of Alzheimer's were not only nonmedical, but not necessarily explanations of illness per se. Alzheimer's was presented instead as a way of being, predominantly characterized by views of the sufferer as childlike and by issues of continuity/discontinuity, though some saw Alzheimer's as part of a larger picture.
Clinical Pharmacology of Rapacuronium Bromide, a New Short‐Acting Neuromuscular Blocking Agent
Authors: Larijani Ghassem E. , Zafeiridis Andreas , Goldberg Michael E.
Published: April 2004

Rapacuronium is a new steroidal, nondepolarizing, neuromuscular blocking agent. It appears to be the least potent of all available nondepolarizing muscle relaxants. Its onset of action resembles that of succinylcholine, and its recovery times are shorter than those of other nondepolarizing agents. The clinical duration of rapacuronium can be shortened significantly with early (2 min) administration of neostigmine, which may be beneficial in patients with difficult airway or failed intubation. Rapacuronium appears to be free of significant cardiovascular complications.
Diagnosis and Treatment of Complicated Tubercular Meningitis
Authors: Kelly Julia J. , Horowitz Edward A. , Destache Christopher J. , Fruin Alan H. , Long Vicki A.
Published: April 2004

A 41‐year‐old woman was seen in no acute distress with an infected ventriculoperitoneal shunt. She underwent several revisions of the shunt but was readmitted to the hospital with nausea, vomiting, and neurologic sequelae. Results of spinal fluid analysis were white blood cells 68/mm3 (25% neutrophils), glucose less than 20 mg/dl, and protein 513 mg/dl. Cerebrospinal fluid, aerobic and anaerobic, and blood cultures were negative. Three weeks later the patient suffered a seizure and was prescribed antitubercular agents for a presumed diagnosis of tubercular meningitis. One week later, chest wound culture from her first visit suggested Mycobacterium tuberculosis, which was confirmed by DNA probe; cerebrospinal fluid culture eventually grew the organism. The patient fared well once she received antituberculosis agents. The time between first contact and treatment in the hospital delayed therapy.
Peripheral Neuropathy in Healthy Men Volunteers Anesthetized with 1.25 MAC Sevoflurane for 8 Hours
Authors: Goldberg Michael E. , Larijani Ghassem E. , Eger Edmond I
Published: April 2004

Two men volunteers developed peripheral neuropathy after prolonged anesthesia with 1.25 minimum alveolar concentration sevoflurane at an inflow rate of 2 L/minute of fresh gas that caused concurrent administration of relatively large doses (ppm‐hrs) of the degradation product of sevoflurane, compound A. Other similarly treated volunteers had lesser degrees of transient neuropathy. This result does not prove but raises the question of whether compound A or other factors associated with sevoflurane anesthesia can predispose patients to peripheral neuropathy.
Comparison of Five β‐Lactam Antibiotics Against Common Nosocomial Pathogens Using the Time Above MIC at Different Creatinine Clearances
Authors: Kays Michael B.
Published: April 2004

Study Objective. To compare the time above the minimum inhibitory concentration (T>MIC) for five parenteral β‐lactam antibiotics against common nosocomial bacterial pathogens at different creatinine clearances (Clcr).

Interventions. Serum concentration‐time profiles were simulated for cefepime, ceftazidime, piperacillin, piperacillin‐tazobactam, and imipenem at Clcr ranging from 120‐30 ml/minute. The MIC data for 90% of organisms (MIC90) were collected for Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Citrobacter freundii, Enterobacter aerogenes, Enterobacter cloacae, Pseudomonas aeruginosa, and oxacillin‐susceptible Staphylococcus aureus, and a weighted geometric mean MIC90 was calculated. The T>MIC was calculated as percentage of the dosing interval in which free concentrations exceeded the weighted geometric mean MIC90. A T>MIC of 70% or greater was considered desirable for all organisms except S. aureus (≥ 50%).

Measurements and Main Results. Cefepime 2 g every 12 hours (Clcr ≥ 70 ml/min) and every 24 hours (Clcr ≤ 60 ml/min) achieved desirable T>MIC for all Enterobacteriaceae and S. aureus at every Clcr. Imipenem 0.5 g achieved desirable T>MIC for E. coli, K. pneumoniae, C. freundii, and S. aureus at every Clcr. However, imipenem T>MIC was less than 70% for the following regimens and organisms: S. marcescens 0.5 g every 6 hours (Clcr ≥ 90 ml/min), E. aerogenes 0.5 g every 6 hours (Clcr ≥ 80 ml/min), E. cloacae 0.5 g every 6 hours (Clcr ≥ 100 ml/min), S. marcescens 0.5 g every 8 hours (Clcr 60–70 ml/min), E. cloacae 0.5 g every 8 hours (Clcr 60–70 ml/min), and E. aerogenes 0.5 g every 8 hours (Clcr 50–70 ml/min). Ceftazidime 2 g every 8 hours (Clcr 60–100 ml/min) and every 12 hours (Clcr 40–50 ml/min) achieved desirable T>MIC for E. coli, K. pneumoniae, S. marcescens, and S. aureus only. At every dose and Clcr, piperacillin‐tazobactam achieved desirable T>MIC for S. aureus but not for any Enterobacteriaceae at Clcr > 50 ml/minute. Piperacillin did not achieve desirable T>MIC for any organism, and none of the β‐lactams attained a T>MIC of 70% or above for P. aeruginosa at any Clcr.

Conclusion. At every Clcr, cefepime achieved a desirable T>MIC for more nosocomial pathogens than any other β‐lactam evaluated. Based on pharmacodynamic data, cefepime is an appropriate empiric choice for treatment of nosocomial infections. However, when P. aeruginosa is a potential pathogen, empiric combination therapy should be considered.
Clinical Guidelines and Pharmacist Intervention Program for HIV‐Infected Patients Requiring Granulocyte Colony‐Stimulating Factor Therapy
Authors: Engles‐Horton Laura L. , Skowronski Carolyn , Mostashari Farzad , Altice Frederick L.
Published: April 2004

Guidelines, implemented by clinical pharmacists, were developed by the pharmacy and therapeutics subcommittee on a dedicated service caring for hospitalized patients with human immunodeficiency virus infection or the acquired immunodeficiency syndrome (AIDS) who required granulocyte colony‐stimulating factor (G‐CSF) therapy. Drug use and evaluation was conducted on all patients with AIDS who were prescribed G‐CSF, and education was provided to medical house staff. Clinical data from chart review and laboratory and billing data bases of the hospital medical information system were compared for the 9‐month intervention period (IP) with data from the 9‐month preintervention period (PIP). Comparing the IP and PIP, the mean number of G‐CSF doses (0.29 vs 0.51) and pharmacy costs per day ($112 vs $200) decreased, with no change in the number of patients requiring G‐CSF. The 1.3 pharmacist interventions per patient resulted in a decrease to 2.4 doses per admission from a baseline of 5.9 (p<0.0001). Mean hospital stay (11.9 vs 13.8 days) and mean number of days of neutropenia did not differ for IP and PIP groups. Effectively implemented pharmacist‐based interventions can decrease hospital costs without increasing patient morbidity.
Clinical Efficacy of Eprosartan
Authors: Weber Michael
Published: April 2004

Eprosartan is a new, structurally distinct, nonbiphenyl, nontetrazole, nonpeptide, orally active angiotensin II receptor antagonist that is highly selective for the AT1 receptor. In placebo‐controlled trials, it led to a dose‐related antihypertensive response, clinically significant reductions in blood pressure and full 24‐hour blood pressure control with once/day administration of 600 mg. Eprosartan provides clinically significant reductions in blood pressure in patients with mild to severe hypertension regardless of age, gender, and race. The antihypertensive effect of eprosartan is comparable with those of other antihypertensive agents. Whereas a relationship exists between dosage and antihypertensive effect, there is no such relationship between dosage and adverse events, the frequency of which is comparable with that with placebo.
Nitric Acid, Nitrous Acid, and Nitrogen Oxides
Authors: Thiemann Michael , Scheibler Erich , Wiegand Karl Wilhelm
Published: April 2004

The article contains sections titled:

1.Nitric Acid1.1.Introduction1.2.Properties1.3.Industrial Production1.3.1.Oxidation of Ammonia1.3.2.Oxidation and Absorption of Nitrogen Oxides1.3.3.Equipment1.3.3.1.Filters and Mixers1.3.3.2.Burners and Waste‐Heat Boilers1.3.3.3.Compressors and Turbines1.3.3.4.Heat Exchangers and Columns1.3.3.5.Construction Materials1.3.4.Processes1.3.4.1.Weak Acid Processes1.3.4.2.Concentrated Acid Processes1.4.Environmental Protection1.4.1.Wastewater1.4.2.Stack Gas1.4.2.1.Emission Limits1.4.2.2.Analysis1.4.2.3.Control of NOxEmissions1.5.Storage and Transportation1.6.Uses and Economic Aspects2.Nitrous Acid3.Nitrogen Oxides3.1.Dinitrogen Monoxide3.2.Nitrogen Monoxide3.3.Nitrogen Dioxide and Dinitrogen Tetroxide3.4.Dinitrogen Trioxide3.5.Dinitrogen Pentoxide4.Toxicology and Occupational Health
Reactive Dyes
Authors: Tappe Horst , Helmling Walter , Mischke Peter , Rebsamen Karl , Reiher Uwe , Russ Werner , Schläfer Ludwig , Vermehren Petra
Published: April 2004

The article contains sections titled:1.Introduction2.Reactive Systems2.1.Mono‐Anchor Dyes2.2.Double‐Anchor Dyes2.3.Multiple‐Anchor Dyes3.Chromogens3.1.Azo Dyes3.2.Anthraquinone Dyes3.3.Triphenodioxazine Dyes3.4.Formazan Dyes3.5.Phthalocyanine Dyes4.Synthetic Procedures5.Uses5.1.Forms of Supply5.2.Dyeing Processes
Scrapie‐specific neuronal lesions are independent of neuronal PrP expression
Authors: Jeffrey Martin , Goodsir Caroline M. , Race Richard E. , Chesebro Bruce
Published: April 2004

In the transmissible spongiform encephalopathies (TSE), accumulation of the abnormal disease‐specific prion protein is associated with neurodegeneration. Previous data suggested that abnormal prion protein (PrP) could induce neuronal pathology only when neurons expressed the normal form of PrP, but conflicting evidence also has been reported. Understanding whether neuronal PrP expression is required for TSE neuropathological damage in vivo is essential for determining the mechanism of TSE pathogenesis. Therefore, these experiments were designed to study scrapie pathogenesis in vivo in the absence of neuronal PrP expression. Hamster scrapie (strain 263K) was used to infect transgenic mice expressing hamster PrP in the brain only in astrocytes. These mice previously were shown to develop clinical scrapie, but it was unclear whether the brain pathology was caused by damage to astrocytes, neurons, or other cell types. In this electron microscopic study, neurons demonstrated TSE‐specific pathology despite lacking PrP expression. Abnormal PrP was identified around astrocytes, primarily in the extracellular spaces of the neuropil, but astrocytes showed only reactive changes and no damage. Therefore, in this model the pathogenesis of the disease appeared to involve neuronal damage associated with extracellular astrocytic accumulation of abnormal PrP acting upon nearby PrP‐negative neurons or triggering the release of non‐PrP neurotoxic factors from astrocytes.
Spectroscopic imaging of arteries and atherosclerotic plaques
Authors: Colley C. S. , Kazarian S. G. , Weinberg P. D. , Lever M. J.
Published: April 2004

Fourier transform infrared (FTIR) spectroscopic imaging using a focal plane array detector has been used to study atherosclerotic arteries with a spatial resolution of 3–4 μm, i.e., at a level that is comparable with cellular dimensions. Such high spatial resolution is made possible using a micro‐attenuated total reflection (ATR) germanium objective with a high refractive index and therefore high numerical aperture. This micro‐ATR approach has enabled small structures within the vessel wall to be imaged for the first time by FTIR. Structures observed include the elastic lamellae of the tunica media and a heterogeneous distribution of small clusters of cholesterol esters within an atherosclerotic lesion, which may correspond to foam cells. A macro‐ATR imaging method was also applied, which involves the use of a diamond macro‐ATR accessory. This study of atherosclerosis is presented as an illustrative example of the wider potential of these ATR imaging approaches for cardiovascular medicine and biomedical applications. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Structure and solvation of melittin in hexafluoroacetone/water
Authors: Gerig J. T.
Published: April 2004

Intermolecular 1H{19F} and 1H{1H} nuclear Overhauser effects have been used to explore interaction of solvent components with melittin dissolved in 50% hexafluoroacetone trihydrate (HFA)/water. Standard nuclear Overhauser effect experiments and an analysis of CαH proton chemical shifts confirm that the conformation of the peptide in this solvent is α‐helical from residues Ala4 to Thr11 and from Leu13 to Arg24. The two helical regions are not collinear; the interhelix angle (144 ± 20°) found in this work is near that observed in the solid state and previous NMR studies. Intermolecular NOEs arising from interactions between spins of the solvent and the solute indicate that both fluoroalcohol and water molecules are strongly enough bound to the peptide that solvent–solute complexes persist for ≥2 ns. Preferential interactions of HFA with many hydrophobic side chains of the peptide are apparent while water molecules appear to be localized near hydrophilic side chains. These results indicate that interactions of both HFA and water are qualitatively different from those present when the peptide is dissolved in 35% hexafluoro‐2‐propanol/water, a chemically similar helix‐supporting solvent system. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
5‐Fluorouracil enhances apoptosis sensitivity of T lymphocytes mediated by CD3ε
Authors: Cheng Hong , Liu Yanxin , Liu Shilian , Zheng Dexian
Published: April 2004

Previous studies by our laboratory have reported that the T cell receptor (TCR) TCR/CD3 complex could mediate activation as well as apoptosis of T lymphocytes. Two tyrosine residues in the ITAM (immuno‐receptor tyrosine‐based activation motifs) of CD3ε were required for apoptosis signalling of Jurkat T lymphocytes. Stable cell lines TJK and T3JK produced from CD8− Jurkat T lymphocytes by transfection with wild‐type and mutant CD8ε (fusion of the extracellular and transmembrane domains of human CD8α to the intracellular domain of mouse CD3ε), were used with CD8− Jurkat T lymphocytes for studying the role of single intact CD3ε. 5‐Fluorouracil (5‐FU), a chemotherapeutic drug can induce cell death of many tumour cell lines. In the present experiments, we examined the expression of caspase‐3, p53 and Bid in the three cell lines induced by 5‐FU and/or anti‐CD8 antibody. We found high expression of p53 during activation‐induced cell death of TJK cells mediated by anti‐CD8 antibody and apoptosis of TJK and T3JK induced by 5‐FU, implicating p53 involvement in apoptosis of leukemia cells induced by anti‐CD8 antibody and 5‐FU. We also detected the active form of caspase‐3 and Bid in apoptotic leukemia cells after treatment with 5‐FU and/or anti‐CD8 antibody, indicating that the drug and antibody induced cell death through caspase‐3 and the signal pathway may involve the Bcl‐2 protein family. Our results showed that combined treatment with 5‐FU and anti‐CD8 antibody could enhance the rate of apoptosis induced by 5‐FU or anti‐CD8 antibody through increased expression of p53 and by promoting activation of caspase‐3 and Bid. This suggests that the combination of 5‐FU and anti‐CD8 antibody may play an important role in inducing apoptosis of leukemia cells. Copyright © 2004 John Wiley & Sons, Ltd.
P‐Chiral Monodentate Diamidophosphites − New and Efficient Ligands for Palladium‐Catalysed Asymmetric Allylic Substitution
Authors: Tsarev Vasily N. , Lyubimov Sergey E. , Shiryaev Alexei A. , Zheglov Sergey V. , Bondarev Oleg G. , Davankov Vadim A. , Kabro Anzhelika A. , Moiseev Sergey K. , Kalinin Valery N. , Gavrilov Konstantin N.
Published: April 2004

Novel P*‐monodentate diamidophosphite ligands have been prepared by a one‐step phosphorylation of alcohols or amines. Both the electronic and the steric demands of the ligands have been estimated quantitatively. Neutral [Pd(allyl)Cl(L)] and cationic [Pd(allyl)(L)2]+ BF4− complexes have been obtained by starting from [Pd(allyl)Cl]2. The new ligands have demonstrated high enantioselectivity in the Pd‐catalysed allylic substitution reactions of 1,3‐diphenylallyl acetate with NaSO2pTol (up to 97% ee), PhCH2NH2 (up to 95% ee) and CH2(CO2Me)2 (up to 97% ee). Application of the P*‐monodentate diamidophosphites to the asymmetric catalytic synthesis of chiral carborane derivatives has also been demonstrated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Stereoselective Synthesis of New Higher Carbon Sugars from D‐Xylose
Authors: Liu Hong‐Min , Zou Da‐Peng , Zhang Fuyi , Zhu Wei‐Guo , Peng Tao
Published: April 2004

A simple, one‐pot multi‐step route for the synthesis of a higher carbon sugar 3 by the HDA reaction of a α,β‐unsaturated ketone prepared in situ from protected D‐xylose with PDC in C6H6 or CH3CN, followed by the reduction to the C10 higher carbon sugar derivatives 4 and 5, is described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of Glycosaminoglycan Oligosaccharides − An Unexpected Inhibitory Effect of a Remote N‐Acetyl Group upon Trichloroacetimidate‐Mediated Couplings
Authors: Lucas Ricardo , Hamza Daniel , Lubineau André , Bonnaffé David
Published: April 2004

In order to prepare biologically relevant heparan sulfate (HS) tetrasaccharide fragments containing an N‐acetylated glucosamine at the reducing end, we studied the glycosylation reaction between the 2‐azidoglucose trichloroacetimidate disaccharide donor 1 and a range of 4′‐OH‐uronyl disaccharide acceptors with an N‐acetylglucosamine at the reducing terminus. Although we tried several condensation conditions, no tetrasaccharide was formed. We show that the failure of these reactions is due to the presence of the N‐acetyl group, which inhibits the trichloroacetimidate‐mediated glycosylation, since the analogous reaction proceeds smoothly once the N‐acetyl group has been replaced by an azide. In the latter case, we show that the careful optimisation of the solvent system is a powerful way to obtain high yields and α‐stereoselectivity in coupling reactions of 1 with the 4‐OH of a GlcUA acceptor. Thus, in a THF/Et2O (9:1) system, we obtained the GlcUA‐β‐(1→4)‐GlcN3‐α‐(1→4)‐GlcUA‐β‐(1→4)‐GlcN3 tetrasaccharide 16α/β in 90% isolated yield and 92:8 α/β ratio, as compared to 57% yield and 70:30 α/β ratio when CH2Cl2 was used. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Phosphonate Aldehyde Annulation − A One‐Pot Synthesis of Hydroxycycloalkenoic Esters − Application to Analogs of Glycinoeclepin A
Authors: Kraus George A. , Choudhury Prabir K.
Published: April 2004

The reaction of ketone enolates with phosphonate aldehydes afforded cyclopentenols or cyclohexenols in a one‐pot procedure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Direct Nucleophilic Addition versus a Single‐Electron Transfer Pathway of σH Adduct Formation in Vicarious Nucleophilic Substitution of Hydrogen
Authors: Mąkosza Mieczysław , Kwast Andrzej
Published: April 2004

Two mechanistic pathways of formation of σH adducts, which are key intermediates in the vicarious nucleophilic substitution of hydrogen, namely direct nucleophilic addition of carbanions to nitroarenes and a two‐step mechanism involving an electron‐transfer process, are discussed on the basis of the existing data and results of the VNS reactions in which a radical probe — chloromethyl aryl sulfone bearing a 2,2‐dimethylcyclopropyl substituent — was used as the carbanion precursor. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Cerium(III) Triflate versus Cerium(III) Chloride: Anion Dependence of Lewis Acid Behavior in the Deprotection of PMB Ethers
Authors: Bartoli Giuseppe , Dalpozzo Renato , Nino Antonio De , Maiuolo Loredana , Nardi Monica , Procopio Antonio , Tagarelli Antonio
Published: April 2004

Cerium(III) triflate deprotects p‐methoxybenzyl ethers of simple alcohols better than the cerium(III) chloride/sodium iodide system. It can be used in 1% M instead of equimolecular amounts, giving better yields. Aromatic alcohols rearrange, but the addition of a scavenger overcomes this drawback. Unfortunately, unsaturated alcohols are deprotected with decomposition, probably due to side electrophilic additions to double bonds. A comparison between the mechanisms of cerium triflate and cerium chloride is reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Characterization and enantiomeric distribution of some terpenes in the essential oil of a Uruguayan biotype of Salvia sclarea L.
Authors: Lorenzo Daniel , Paz Daniel , Davies Philip , Villamil José , Vila Roser , Cañigueral Salvador , Dellacassa Eduardo
Published: April 2004

A biotype of clary sage (Salvia sclarea L.) growing in Uruguay was evaluated for its suitability to be cultivated in Uruguay. Essential oils from the inﬂorescences and leaves of plant harvested at full ﬂowering and early seed ripeness stages were obtained by steam distillation and characterized by GC and GC–MS (quadrupole). Twenty‐seven components (91–98% of the total composition) were identiﬁed. The oil was characterized by a high content of linalool (8–22%), linalyl acetate (39–48%) and sesquiterpenes, with germacrene D (8–20%) and (E)‐β‐caryophyllene (3–5%) as the main components. The enantiomeric distribution of α‐pinene, sabinene, β‐pinene, limonene, linalool, linalyl acetate and germacrene D was studied by multidimensional HRGC–HRGC. The development stage did not inﬂuence the oil composition or the enantiomeric distribution of the studied components of the clary sage biotype over the period of evaluation. It is concluded that clary sage can be grown as an economically viable crop in the south of Uruguay. Copyright © 2004 John Wiley & Sons, Ltd.
Essential oils of Varthemia iphionoides from Jordan
Authors: Avato P. , Raffo F. , Aldouri N. A. , Vartanian S. T.
Published: April 2004

The essential oil obtained from plants of Varthemia iphionoides growing wild in Jordan has been analysed by GC and GC–MS. The major consituents are represented by borneol (49.3%) and its acetyl and formyl esters. Copyright © 2004 John Wiley & Sons, Ltd.
Terpenoids of the volatile oil of Bursera graveolens
Authors: Yukawa Chiyoki , Iwabuchi Hisakatsu , Kamikawa Tadao , Komemushi Sadao , Sawabe Akiyoshi
Published: April 2004

In the course of studies on the constituents of the woody material of Bursera graveolens, the aroma components that provide its characteristic spicy, sweet and balsamic odor were investigated using GC/MS. Five compounds, 1–5, were isolated from the volatile oil obtained by diethyl ether extraction of B. graveolens wood chips, and their structures were elucidated by means of NMR studies. Their structures were determined as (−)‐dihydro‐α‐agarofuran (1), (−)‐5,11‐epoxy‐4α,5β,10α‐eudesm‐1‐ene (2), (−)‐4α‐hydroxydihydroagarofuran (3), (−)‐3β,4β‐oxidoagarofuran (4) and (−)‐10‐epi‐γ‐eudesmol (5). Of these, (−)‐5,11‐epoxy‐4α,5β,10α‐eudesm‐1‐ene (2) is a new sesquiterpenoid that has not previously been reported in literature, and the presence of (−)‐dihydro‐α‐agarofuran (1), (−)‐4α‐hydroxydihydroagarofuran (3), (−)‐3β,4β‐oxidoagarofuran (4) and (−)‐10‐epi‐γ‐eudesmol (5) in B. graveolens is reported for the ﬁrst time. Copyright © 2004 John Wiley & Sons, Ltd.
Enzyme‐mediated synthesis of new 1,3‐dioxane odorants related to Floropal®
Authors: Abate Agnese , Brenna Elisabetta , Fuganti Claudio , Serra Stefano
Published: April 2004

The enzyme‐mediated synthesis of enantiomerically enriched 1,3‐dioxane odorants analogous to Floropal® is here described. The complete olfactory evaluation of each sample is also reported. The addition of a single methyl group at C5 of the dioxane ring of Floropal® modiﬁes the elicited odour sensation, still preserving a pleasant character. The substitution of the methyl group at C6 with just an ethyl moiety completely changes the odour proﬁle of the molecule. Even subtler are the odour differences generated by conﬁgurational variations. Copyright © 2004 John Wiley & Sons, Ltd.
Development of hydroxyapatite bone scaffold for controlled drug release via poly(ϵ‐caprolactone) and hydroxyapatite hybrid coatings
Authors: Kim Hae‐Won , Knowles Jonathan C. , Kim Hyoun‐Ee
Published: April 2004

A scaffold‐coating design, the hydroxyapatite (HA) porous bone scaffold coated with poly(ϵ‐)caprolactone (PCL) and HA powder hybrids, was developed for use as tissue‐regeneration and controlled‐release system. An antibiotic drug, tetracycline hydrochloride (TCH), was encapsulated within the hybrid coating layer through a dip‐coating and solvent‐casting method. Coating cycle and drug loading amount differed to control the level of drug‐release rate. The HA scaffold framework, obtained by a polymeric foam reticulate method, exhibited a highly porous structure, with porosity and pore size of approximately 87% and 180 μm, respectively. The hybrid layer, consisting of PCL sheet and HA fine powders, was uniformly coated on the scaffold surface. The coating layer exhibited only PCL and HA phases and structures, revealing no chemical interaction among the coating components, as observed by X‐ray diffraction (XRD) and Fourier‐transform infrared (FTIR) analyses. The coated‐HA scaffolds showed an effective stress distribution behavior in response to an applied load, as confirmed by the compressive stress–strain curve. The mechanical properties of the coated scaffolds were improved highly with coatings; the compressive strength and elastic modulus of the cyclic coated scaffolds were ∼3–4 times, and the energy absorption were ∼8 times, higher than those without coating. These improvements were attributed mainly to the shielding of framework flaws by a flexible coating layer and partially to the thicker stems (porosity reduction). The dissolution of the coated scaffolds in a phosphate‐buffered saline (PBS) solution increased with incubation time. The drug was released sharply within the initial several hours (∼2 h), but the rate decreased further, showing a sustained release. The release amount was well controlled via coating‐cycle and initial drug loading amount, suggesting the effectiveness of the coating‐scaffold design as a drug‐delivery system. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 240–249, 2004
Leveled Steric Effect in Alkoxyamines of SG1‐Type
Authors: Acerbis Sébastien , Beaudoin Emmanuel , Bertin Denis , Gigmes Didier , Marque Sylvain , Tordo Paul
Published: April 2004

Summary: During nitroxide mediated polymerization (NMP) the polymerization time decreases with the increasing rate constant of the cleavage of the NOC bond of the dormant alkoxyamines. Hence, the knowledge of the factors influencing this cleavage is of considerable interest. Recently, we demonstrated that the influence of the nitroxyl moieties of 24 alkoxyamines on the values of the rate constant for the homolysis of the CON bond of the alkoxyamine (kd) was accounted for by a biparametric equation log kd = −3.07 × σU − 0.88 × Es − 5.88, with σU for the universal electrical effect and Es for the steric demand of the substituents bound to the nitroxyl function. During the course of the work, it was assumed for a number of molecules that the steric effect was leveled. We present herein three new SG1‐based alkoxyamines with sufficiently different steric strains to confirm the leveled steric effect.

The fit of the rate constant for the homolysis of the CON bond of the alkoxyamines (kds) with the equation log kd = −0.37 × σU − 0.88 × Es when a leveled steric effect is assumed.

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The fit of the rate constant for the homolysis of the CON bond of the alkoxyamines (kds) with the equation log kd = −0.37 × σU − 0.88 × Es when a leveled steric effect is assumed.
Copolymerization of Ethylene Carbonate and 1,2‐Propylene Carbonate with Tetramethylene Urea and Characterization of the Polyurethanes
Authors: Ubaghs Luc , Novi Christina , Keul Helmut , Höcker Hartwig
Published: April 2004

Summary: Tetramethylene urea (TeU, 1) is successfully copolymerized with 1,2‐propylene carbonate (PC, 2) leading to a polyurethane ($\overline M _{\rm n}$ = 12 200; $\overline M _{\rm w}$ 18 400; $\overline M _{\rm w} /\overline M _{\rm n}$ = 1.50) with a Tm of 145.7 °C and a Tg of 53.7 °C. Mechanistic studies with a blocked isocyanate model compound revealed that, at no stage of the reaction is the TeU ring opened to form an isocyanate. Hence, a well‐underlined mechanism for the copolymerization is proposed. Furthermore, TeU is successfully copolymerized with mixtures of PC and ethylene carbonate (EC, 3). From NMR spectroscopic data of the polyurethanes obtained, it is concluded that PC is less reactive than EC. However, it is possible to increase the PC content in poly(TeU‐EC‐stat‐TeU‐PC) by increasing the PC/EC ratio in the feed. 13C NMR spectroscopy reveals that a random copolymer is obtained. This conclusion is supported by differential scanning calorimetry (DSC) data, which show a continuous decrease in Tm with increasing PC content.

Tm was found to decrease with increasing PC content.

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Tm was found to decrease with increasing PC content.
Synthesis of Poly(ethylene oxide)s with 1,2,4‐Triazol‐4‐yl End Groups – Macroligands for Bistable Metal‐Polymer Complexes
Authors: Saf Robert , Schwarzenbacher Gerald , Mirtl Christian , Hayn Gertraud , Hobisch Josefine , Gatterer Karl
Published: April 2004

Summary: Poly(ethylene oxide) methyl ether 4H‐1,2,4‐triazol‐4‐yl (1) has been synthesized as a novel macroligand. ESI‐MS (electrospray ionisation mass spectrometry), MALDI‐TOF (matrix‐assisted laser desorption ionisation time‐of‐flight) MS as well as NMR spectroscopy were used for the accurate determination of number‐average molecular weights ($\overline M _{\rm n}$), the crucial parameter for subsequent synthesis of metal‐polymer complexes of four different samples 1a–d. Reaction of polymer 1a with [Fe(H2O)6](nps)2 (nps = 3‐nitrophenylsulfonate) gave [Fe(1a)3](nps)2, a bistable metal‐polymer complex that exhibited low‐spin (LS) to high‐spin (HS) transitions around T1/2 = 257 K, accompanied by a change in colour from violet (LS) to slightly yellow (HS).

The structure of [Fe(1a)3](nps)2 and its magnetic properties.

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The structure of [Fe(1a)3](nps)2 and its magnetic properties.
Heterogeneity Features of Bulk Atom Transfer Radical Polymerization of Methyl Methacrylate in an Ampoule Reactor
Authors: Wang Aileen R. , Zhu Shiping
Published: April 2004

Summary: This work demonstrated the severity of heterogeneity issues with ampoule reactors in bulk atom transfer radical polymerization of methyl methacrylate. The kinetic data of CuII concentration, monomer conversion, and polymer molecular weight varied from location to location along the ampoule. However, the polymer molecular weight versus conversion data from different locations fell into a single theoretical line. All locations except for the bottom part of the ampoule produced polymers having narrow molecular weight distribution.

Conversion versus time at different locations for the ATRP of MMA at 70 °C.

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Conversion versus time at different locations for the ATRP of MMA at 70 °C.
Molecular weight determination of coordination and organometallic oligomers by T1 and NOE constant measurements: concepts and challenges
Authors: Harvey Pierre D.
Published: April 2004

This paper describes how to determine molecular weights of coordination and organometallic polymers (or rather oligomers) in solution using spin‐lattice relaxation time (T1) and Nuclear Overhauser Enhancement constant (ηNOE) measurements. The methodology is explained using simple organometallic‐complexes such as M(CN‐t‐Bu)4+ complexes (M = Cu, Ag). Very good results are obtained for oligomers that exhibit a rigid structure. Conversely, very poor results are extracted when the materials show flexible chains in the backbone. The typical examples for rigid and flexible oligomers are the {Ag(dmb)2+}n (dmb = 1,8‐diisocyano‐p‐menthane), and {Pd2(dmb)2(diphos)2+}n (diphos = dppa, dppb, dpppent, and dpph) as well as {Pd2(diphos)2(dmb)2+}n (diphos = dppe, dppr, and dpppR; R = O(CH2)2O‐naphthyl), respectively.
Synthesis and lithographic applications of highly metallized cluster‐based polyferrocenylsilanes
Authors: Chan Wing Yan , Cheng Alison Y. , Clendenning Scott B. , Manners Ian
Published: April 2004

We report the use of a cobalt‐clusterized polyferrocenylsilane (Co‐PFS) as a precursor to patterned ferromagnetic ceramics. Co‐PFS was synthesized. Functioning as a negative resist, Co‐PFS lines with widths of 10‐300 μm were patterned using UV‐photolithography, while features as small as 500 nm were afforded by electron‐beam lithography. Subsequent pyrolytic treatment of the lithographically patterned Co‐PFS yielded ferromagnetic ceramics containing Fe/Co nanoparticles. Due to its high metal‐loading, Co‐PFS is a good etch resist for oxygen and hydrogen plasma reactive ion etching. Reactive ion etching of a thin film of Co‐PFS in a secondary magnetic field allowed direct access to ferromagnetic ceramic films, providing a viable alternative to pyrolysis.
Induction Melting of NiTi Shape Memory Alloys – The Influence of the Commercial Crucible Graphite on Alloy Quality
Authors: Frenzel J. , Neuking K. , Eggeler G.
Published: April 2004

The present work studies the performance of three different kinds of commercial crucible graphite materials used during inductive melting of NiTi‐shape memory alloys (SMAs).

One low‐density extruded graphite and two isostatically pressed graphite‐materials with different porosity and purity were used for melting NiTi‐SMAs from pure Ni and Ti raw materials. The use of a low grade, lower density graphite crucible led to a high carbon contamination of the alloy. Much better results were obtained using graphite crucibles with higher density and higher purity. But in all cases, the first use of a graphite crucible leads to a higher carbon pickup than the second time of utilization. This can be explained by the formation of a protective TiC rich layer on the surface of the crucible during its first contact with the NiTi melt which acts as a diffusion‐barrier later on. Furthermore, attention has to be paid to the thermal conductivity of the graphite. Using a material with a low thermal conductivity may lead to the formation of cracks at the pouring‐lip of the crucible during casting. This may lead to spalling off of crucible material and can enhance the risk of non‐metallic inclusions in the alloy.
Influence of compression aging on phase transition temperatures in single crystalline Ni‐rich NiTi shape memory alloys
Authors: Michutta J. , Yawny A. , Carroll M. C. , Somsen Ch. , Eggeler G.
Published: April 2004

The present paper considers the phase transition behavior of a single crystal Ni‐rich NiTi alloy which was compression aged to produce one single family of Ni4Ti3 precipitates.

The single crystal material was produced in a two stage process.

Polycrystalline material was first melted under an inert atmosphere and remelted when single crystals were produced. Compression aging treatments in <111>‐orientation were carried out in order to suppress all but one family of Ni4Ti3‐precipitates which nucleate and grow on {111}‐planes of the B2 matrix. The objective of this study is to investigate the influence of Ni4Ti3‐precipitates on the martensitic transformation behavior. It was previously shown that grain boundaries provide heterogeneous nucleation sites for the formation of Ni4Ti3; this results in heterogeneous microstructures which undergo multiple step martensitic transformations. Single crystals avoid grain boundaries and the present study aims at clarifying how homogeneously precipitated particles affect martensitic transformations.
PM‐Composites with Nickel‐Titanium Shape Memory Alloys
Authors: Theisen W. , Schuermann A.
Published: April 2004

Starting from NiTi‐powders, composites of nickel‐titanium shape memory alloys (NiTi‐SMA) and different stainless steels as well as of different NiTi‐SMAs were produced by using the process of hot isostatic pressing (HIP). Metallographic investigations focussed on the interface between NiTi‐SMA and stainless steel with special emphasis placed on the characterization of the typical structure of the diffusion zones in both components.
Proximal nerve elongation vs. nerve grafting in repairing segmental nerve defects in rabbits
Authors: Baoguo Jiang , Shibata Minoru , Matsuzaki Hironori , Takahashi Hideaki E.
Published: April 2004

If segmental nerve defects could be repaired by elongating the proximal or distal segments, nerve grafting might be unnecessary. We elongated a 40‐mm proximal segment of an injured median nerve, in the rabbit right forelimb, at a rate of 1 mm/day for 10 days in 10 rabbits and for 15 days in another 10. On the left forelimb of the same rabbits, a 10‐ for 15‐mm segment of the median nerve was removed, and a 10‐ for 15‐mm segment, respectively, of the tibial nerve was grafted in its place. Four months after the initial surgery, nerve conduction velocity (NCV), contractile strength of the flexor digitorum superficialis (FDS), axon count, and axon diameter did not differ significantly between the 10‐mm groups but were better in the 15‐mm grafted group. Elongating the proximal nerve segment may be an alternative to grafting in repairing segmental defects of less than 10 mm. © 2004 Wiley‐Liss, Inc.
A human murine mammary tumour virus‐like agent is an unconvincing aetiological agent for human breast cancer
Authors: Mant Christine , Cason John
Published: April 2004

There has recently been renewed interest in both the scientific literature, and in the media, that a human relative (HMLV) of murine mammary tumour virus (MMTV) may be implicated in the aetiology of up to 42% of sporadic cases of human breast cancer. Such reports are potentially of considerable clinical significance, as aside from the small percentage of genetically acquired breast cancers, the cause of sporadic cases of breast cancer is completely unknown. Indeed, convincing proof of an infectious cause for human breast malignancies would permit the development of new preventative measures, treatment modalities and raise the possibility of prophylactic and therapeutic vaccines. Here we review the historical background for a retroviral cause of human breast cancers and give an up‐to‐date critique of the most recent research findings. We conclude that the available evidence for an infectious aetiology of human breast cancers is unconvincing. Amongst the many cognate arguments against an infective hypothesis for sporadic cases of human breast cancer are the facts that: (i) human tissues lack the appropriate cell‐surface receptor for entry of MMTVs/HMLVs; (ii) unlike all other virally caused human malignancies, immunodeficiency does not predispose to an increased incidence, or prevalence, of human breast cancers; and, (iii) reports of PCR amplification of MMTV/HMLV sequences from breast cancers have been robustly disputed by four independent laboratories. Indeed positive PCR results may be readily explained by the mis‐amplification of host genomic DNA. Hence, the burden of proof currently lies with those who champion a viral cause for sporadic cases of breast cancer. Copyright © 2004 John Wiley & Sons, Ltd.