bluuebunny/crossref_metadata_2025 huggingface dataset:
Tissue distribution and duration of mouse hepatitis virus in naturally infected immunocompetent ICR (CD-1) and immunodeficient athymic nude-nu mouse strains used for ovarian transplantation and in vitro fertilization
Authors: Scavizzi Ferdinando , Raspa Marcello
Published: March 2004

During a natural outbreak of mouse hepatitis virus (MHV) infection in an animal facility in Rome, 6-week-old, outbred, immunocompetent Hsd:ICR (CD-1) and immunodeficient Hsd:athymic nude-nu sentinel mice (barrier maintained) were exposed to MHV in order to study tissue distribution and duration of the virus in naturally infected mice. Infection was diagnosed by serology and by reverse transcriptase-polymerase chain reaction (RT-PCR) using primers directed to two separate but highly conserved regions of the MHV genome. Faeces, colons, spleens, lungs, brains, livers, epididymides, testes, uteri and ovaries from sentinels were tested by RT-PCR after 1, 2, 4, 6, 8 and 12 weeks. A second round of amplification with nested primers was performed to increase the sensitivity of detection. The results indicated that all the organs tested became infected with the virus at various times. Furthermore, male and female reproductive organs were infected within 6 weeks of the beginning of exposure. Investigation of MHV transmission by ovarian transplantation and by in vitro fertilization (IVF) revealed that MHV was transmitted by infected ovaries transplanted into both immunocompetent and immunodeficient mouse strains but transmission was not observed when sperm from infected testes were used for IVF. These results suggest that sperm do not transmit infection from actively infected animals and that IVF could be considered a cleansing procedure.
Rat islet isolation yield and function are donor strain dependent
Authors: de Groot M. , de Haan B. J. , Keizer P. P. M. , Schuurs T. A. , van Schilfgaarde R. , Leuvenink H. G. D.
Published: March 2004

Effective rat islet isolation is pertinent for successful islet transplantation and islet studies in vitro. To determine which rat strain yields the highest number of pure and functional islets, four commonly used rat strains were compared with regard to islet yield, islet purity and islet function. Secretory responses were assessed by stimulation with glucose, and by stimulation with glucose plus 3-isobutyl-1-methylxanthine (IBMX). We show that rat islet function and isolation yield are donor strain dependent. Albino Oxford (AO) rats donated twice as many islets than Wistar, Lewis and Sprague Dawley (SD) rats. Stimulation with glucose plus IBMX resulted in an average five-fold increase of the stimulation index of AO, Lewis, Wistar and SD rats compared to stimulation with glucose only. AO islets had improved secretory responses after a one-week culture period, but required the addition of IBMX to glucose to elicit a distinguished stimulated insulin secretion after 2 days of culture. Islets from SD rats showed inferior results with regard to purity immediately after isolation and with regard to function after short- and after long-time culture. Because Lewis islets possessed the highest secretory response to glucose (without IBMX) immediately after isolation, Lewis rats may be preferred as islet donors for immediate use. The addition of IBMX to glucose for in vitro functional testing is recommended because it elicits high insulin secretory responses of islets regardless of the rat strain. AO rats are preferred for culture experiments since the number of experimental animals is reduced two-fold compared to Lewis, Wistar and SD rats.
Dexmedetomidine Overdose in the Perioperative Setting
Authors: Jorden Victor SB , Pousman Robert M , Sanford Mary M , Thorborg Per AJ , Hutchens Michael P
Published: March 2004

OBJECTIVE

To report 3 cases of accidental dexmedetomidine overdose in the perioperative setting and review the pathophysiology of α2-agonist overdose.

CASE SUMMARIES

Three patients accidentally received overdoses of dexmedetomidine, one intraoperatively (192 μg over 20 min) and 2 postoperatively (4 and 2 rather than 0.4 and 0.2 μg/kg/h; 0.5 μg/kg/min rather than 0.5 μg/kg/h). Hemodynamic parameters remained stable for all 3 patients. The most notable sign was oversedation diagnosed either clinically or using a bispectral index monitor; Naranjo criteria suggest possible or probable association of the reactions with dexmedetomidine. In all 3 cases, oversedation resolved within one hour of drug discontinuation. There were no other sequelae, and the remainder of each patient's hospital course was unremarkable.

DISCUSSION

As of this writing, dexmedetomidine dosing in excess of the label recommendation has been reported, but accidental dexmedetomidine overdose in clinical practice has not been described. Excessive levels of sedation were the only significant finding in all 3 patients. Dexmedetomidine's short redistribution half-life of 6 minutes should lead to rapid resolution of oversedation induced by overdoses if the overall duration of infusion is short (≤8 h). While the patients reported here were hemodynamically stable, dexmedetomidine may engender significant hemodynamic changes either because of sympatholysis at normal doses or vasoconstriction at higher than recommended doses. The absence of a significant hypertensive response to high dexmedetomidine concentrations suggests that dexmedetomidine-induced hypertension may be multifactorial, not simply related to plasma drug concentrations.

CONCLUSIONS

Practitioners presented with dexmedetomidine overdose should be prepared to manage oversedation. While hemodynamic alterations may be seen with dexmedetomidine use, hypertension from high dexmedetomidine plasma concentrations is not a consistent response. Practitioners using dexmedetomidine should carefully note that dosing for this agent is described by the manufacturer in μg/kg/h, not μg/kg/min.
Intermittent Visceral Edema Induced by Long-Term Enalapril Administration
Authors: Orr Katherine K , Myers James R
Published: March 2004

OBJECTIVE

To describe a case of intermittent visceral angioedema associated with long-term enalapril use.

CASE SUMMARY

A 72-year-old white woman developed severe abdominal pain as a result of visceral angioedema associated with long-term enalapril therapy. She had been taking enalapril 20 mg/day for 9 years prior to the first reported episodes of abdominal pain.

DISCUSSION

Visceral angioedema associated with angiotensin-converting enzyme (ACE) inhibitors is a documented adverse effect. However, onset of symptoms has never been reported after 9 years of use. Not until 2 years after initial presentation were the symptoms correlated to enalapril administration. Since discontinuation of enalapril, the patient has not reported any symptoms for >2 years. An objective causality assessment categorized this adverse drug event as a result of enalapril as possible.

CONCLUSIONS

Development of angioedema from ACE inhibitors occurs in <1% of the population. Limited case reports have identified intermittent visceral angioedema from ACE inhibitors. However, it is important to recognize that this adverse effect can also occur in patients who have been treated with ACE inhibitor therapy for several years.
Synthetic Peptide Studies on the Severe Acute Respiratory Syndrome (SARS) Coronavirus Spike Glycoprotein: Perspective for SARS Vaccine Development
Authors: Choy Wai-Yan , Lin Shu-Guang , Chan Paul Kay-Sheung , Tam John Siu-Lun , Lo Y M Dennis , Chu Ida Miu-Ting , Tsai Sau-Na , Zhong Ming-Qi , Fung Kwok-Pui , Waye Mary Miu-Yee , Tsui Stephen Kwok-Wing , Ng Kai-On , Shan Zhi-Xin , Yang Min , Wu Yi-Long , Lin Zhan-Yi , Ngai Sai-Ming
Published: March 2004

Background: The S (spike) protein of the etiologic coronavirus (CoV) agent of severe acute respiratory syndrome (SARS) plays a central role in mediating viral infection via receptor binding and membrane fusion between the virion and the host cell. We focused on using synthetic peptides for developing antibodies against SARS-CoV, which aimed to block viral invasion by eliciting an immune response specific to the native SARS-CoV S protein.

Methods: Six peptide sequences corresponding to the surface regions of SARS-CoV S protein were designed and investigated by use of combined bioinformatics and structural analysis. These synthetic peptides were used to immunize both rabbits and monkeys. Antisera collected 1 week after the second immunization were analyzed by ELISA and tested for antibody specificity against SARS-CoV by immunofluorescent confocal microscopy.

Results: Four of our six synthetic peptides (S2, S3, S5, and S6) elicited SARS-CoV-specific antibodies, of which S5 (residues 788–820) and S6 (residues 1002–1030) exhibited immunogenic responses similar to those found in a parallel investigation using truncated recombinant protein analogs of the SARS-CoV S protein. This suggested that our S5 and S6 peptides may represent two minimum biologically active sequences of the immunogenic regions of the SARS-CoV S protein.

Conclusions: Synthetic peptides can elicit specific antibodies to SARS-CoV. The study provides insights for the future development of SARS vaccine via the synthetic-peptide-based approach.
Free radical graft copolymerization of poly(n‐butyl methacrylate) and poly(butyl acrylate) onto chlorinated rubber: Characterization and mechanical properties
Authors: Ahmed Shanaz , Radhakrishnan N. , Srinivasan K. S. V. , Sanjeevi R.
Published: March 2004

Graft copolymerization of n‐butyl methacrylate and butyl acrylate onto chlorinated rubber was carried out in solution medium (xylene) using benzoyl peroxide as initiator. The chlorinated rubber‐g‐(n‐butyl methacrylate‐co‐butyl acrylate) (CR‐g‐nBMA‐co‐BA) was isolated from the copolymerization mixture by extracting with isopropyl ether. Infrared (FT‐IR) spectra, proton nuclear magnetic resonance (1H NMR) and thermogravimetric analysis of the graft copolymer showed the occurrence of grafting. Percent grafting and grafting efficiency calculated under different experimental conditions are discussed. The mechanical properties of the grafted CR films were studied under different strain rates. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 103–110, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20003
The Analysis of the Seasonal, Spatial, and Compositional Distribution of Humic Substances in a Subtropical Shallow Lake
Authors: Mazzuoli Stefania , Loiselle Steven , Hull Vincent , Bracchini Luca , Rossi Claudio
Published: March 2004

The spatial and temporal distribution of humic substances in aquatic ecosystems can have important effects on ecosystem productivity, negatively impacting primary productivity while positively impacting secondary productivity. In the present investigation, a large shallow lake ecosystem was studied to determine the spatial and seasonal variation of the composition and concentration of humic substances. Concentrations of total dissolved organic matter, humic acid, and fulvic acid were found to display significant spatial distributions (1.3…13.5 mg/L, DOM; 0.1…5.4 mg/L, HA). The distribution is described by using mapping techniques and the analysis of the spatial distribution of the lake. An analysis of the seasonal variations also indicated the dependence of the occurrence of these compounds on meteorological and hydrological conditions.

To identify the potential sources of these organic materials, an analysis was made of the ratio of humic and fulvic acid fractions and total DOM. It was found that areas of high DOM concentration coincided with the areas of highest HA percentage of total DOM. Furthermore using the ratio of the normalised concentrations of HA, FA, and residual DOM (< 5000 g/mol) it was found that areas dominated by each are spatially distinct. This confirms the hypothesis that in these shallow lakes, photodegradation and bacterioplankton activity will create a residence time dependent zonation of each component of the total DOM.
Optimization of the Sampling Technique for the Determination of Dissolved Hydrogen in Groundwater
Authors: Heimann Axel , Marczinek Silke , Kloosb Karin , Peiffer Stefan
Published: March 2004

In this study a field‐sampling technique for dissolved hydrogen (H2) in groundwater will be presented which allows the transport of gaseous samples into the laboratory for further analysis. The method consists of transferring the headspace trapped in a gas‐sampling bulb which is continuously purged by groundwater into previously evacuated vials using a gas‐tight syringe. Three transfer steps with preceding evacuation of the vial led to a H2‐recovery of 100 % in laboratory experiments. The method has been applied to determine H2 concentrations in an aquifer contaminated with chlorinated solvents.

Tests concerning the effect of different pumping techniques on H2 concentrations revealed that most reliable values were obtained with a bladder pump, while an electrically driven submersible pump generated considerable amounts of hydrogen due to electrochemical interactions with the sampled water. Concentrations of dissolved hydrogen in field and laboratory samples were about two orders of magnitude higher when sampling was performed with the electrically driven submersible pump compared to sampling with the bladder pump and a peristaltic pump.

Lab experiments with a Plexiglas reservoir to produce H2‐enriched water were used to study the effect of two tubing materials (PVC, polyamide) on H2 losses. PVC tubing turned out to allow transfer of H2‐enriched water over 25 m without significant losses, while PA‐tubing was not suitable for sampling of H2.
Peroxisome biogenesis disorders with prolonged survival: Phenotypic expression in a cohort of 31 patients
Authors: Poll‐The Bwee Tien , Gootjes Jeannette , Duran Marinus , de Klerk Johannis B.C. , Maillette de Buy Wenniger‐Prick Liesbeth J. , Admiraal Ronald J.C. , Waterham Hans R. , Wanders Ronald J.A. , Barth Peter G.
Published: March 2004

The peroxisome biogenesis disorders (PBDs) with generalized peroxisomal dysfunction include Zellweger syndrome (ZS), neonatal adrenoleukodystrophy (NALD), and infantile Refsum disease (IRD). There is clinical, biochemical, and genetic overlap among the three phenotypes, also known as Zellweger spectrum disorders. Clinical distinctions between the phenotypes are not sharply defined. Only limited sources are available to serve as a background for prognosis in PBD, especially in case of prolonged survival. We delineated the natural history of 31 PBD patients (age 1.2–24 years) through systematic clinical and biochemical investigations. We excluded classical ZS from our study, and included all patients with a biochemically confirmed generalized peroxisomal disorder over 1 year of age, irrespective of the previously diagnosed phenotype. The initial clinical suspicion, age at diagnosis, growth, development, neurological symptoms, organ involvements, and survival are summarized. Common to all patients were cognitive and motor dysfunction, retinopathy, sensorineural hearing impairment, and hepatic involvement. Many patients showed postnatal growth failure, 10 patients displayed hyperoxaluria of whom 4 had renal stones. Motor skills ranged from sitting with support to normal gait. Speech development ranged from non‐verbal expression to grammatical speech and comprehensive reading. The neurodevelopmental course was variable with stable course, rapid decline with leukodystrophy, spinocerebellar syndrome, and slow decline over a wide range of faculties as outcome profiles. At the molecular level, 21 patients had mutations in the PEX1 gene. The two most common PEX1 mutations were the G843D (c.2528G→A) missense and the c.2097insT frameshift mutation. Patients having the G843D/G843D or the G843D/c.2097insT genotypes were compared. Patients homozygous for G843D generally had a better developmental outcome. However, one patient who was homozygous for the “mild” G843D mutation had an early lethal disease, whereas two other patients had a phenotype overlapping with the G843D/c.2097insT group. This indicates that next to the PEX1 genotype other yet unknown factors determine the ultimate phenotype. © 2004 Wiley‐Liss, Inc.
NMR‐Nomenklatur: Kernspineigenschaften und Konventionen für die Angabe chemischer Verschiebungen
Authors: Berger Stefan , Zeller, Leipzig Uta
Published: March 2004

Hier wird eine vereinheitlichte Skala zur Angabe der NMR‐chemischen Verschiebungen aller Kerne relativ zur 1H‐Resonanzfrequenz von Tetramethylsilan (TMS) empfohlen. Diese Skala liefert ein genaues Verhältnis Ξ zwischen der Resonanzfrequenz eines gegebenen Kerns und der primären Referenz, der 1H‐Resonanzfrequenz von TMS in verdünnter Chloroformlösung (Volumenverhältnis φ<1:99). Die Referenzierungsverfahren werden gemeinsam mit Aspekten der praktischen Anwendung der vereinheitlichten Skala diskutiert. Ein Schwerpunkt sind die vorgeschlagenen Referenzverbindungen und die Ξ‐Werte für Sekundärreferenzen auf der vereinheitlichten Skala. Viele dieser Daten sind das Ergebnis neuer Messungen. Einige ältere Empfehlungen zur Wiedergabe chemischer Verschiebungen bleiben gültig. Die chemische Verschiebung δ wird neu definiert, um frühere Unklarheiten zu beseitigen, ohne jedoch die praktische Anwendung zu beeinflussen. Des Weiteren werden die Beziehungen zwischen der vereinheitlichten Skala und kürzlich veröffentlichten Empfehlungen für die Referenzierung in wässrigen Lösungen (speziell bei biochemischen Arbeiten) sowie die speziellen Effekte bei Festkörper‐MAS‐NMR‐Experimenten diskutiert. Insgesamt werden neun neue Empfehlungen zur chemischen Verschiebung gegeben. Darüber hinaus werden standardisierte Kernspindaten (Spinquantenzahl, Isotopen‐Häufigkeit, magnetisches Moment, gyromagnetisches Verhältnis, Rezeptivität sowie, wo angebracht, Quadrupolmoment und Linienbreitefaktor) für die stabilen (und einige instabile) Isotope aller Elemente mit einem Spin ungleich null in tabellarischer Form angegeben.
Task analysis, correspondence training, and general case instruction for teaching personal hygiene skills
Authors: Stokes John V. , Cameron Michael J. , Dorsey Michael F. , Fleming Elizabeth
Published: March 2004

The effect of a 10‐step task analysis, general case instruction, and correspondence training was evaluated for teaching appropriate personal hygiene following bowel movements. Correspondence training maintained a central role in this study. According to Israel (1978), the relationship between an individual's verbal and nonverbal behaviors is influential in self‐instruction training. Essentially, correspondence training encourages an individual to generate his or her own instructional cues; in consequence, the procedure can be instrumental in ensuring the maintenance and generalization of important verbal and nonverbal behavior. Three adults with developmental disabilities participated in this study. The dependent variables included the level of assistance required on each step of the task analysis and an end of sequence rating on a three‐point Likert‐type cleanliness scale. Results showed that all three participants learned to care for themselves appropriately following bowel movements. Moreover, the skills generalized to other settings and were maintained over a nine‐month period. The target skill was evaluated against the five criteria for a behavioral cusp and met the criteria for ‘an important behavior change’ (Bosch & Fuqua, 2001, p. 123). Copyright © 2004 John Wiley & Sons, Ltd.
Functional analysis and treatment of low‐rate problem behavior in individuals with developmental disabilities
Authors: Tarbox Jonathan , Wallace Michele D. , Tarbox Rachel S. F. , Landaburu Heidi J. , Williams W. Larry
Published: March 2004

Extensive research has validated the standard functional analysis as a useful technology for identifying the function of problem behavior in individuals with developmental disabilities. The assessment of low‐rate problem behavior is one area that has yet to receive a significant amount of research. Some problem behaviors may occur at rates too low to be observed during a standard functional analysis, despite the fact that they may be highly destructive behaviors. The current study evaluated the effectiveness of initiating functional analysis sessions contingent on the occurrence of bursts of problem behavior for producing interpretable functional analysis results. While a standard functional analysis did not produce definitive results with respect to behavioral function, the ‘low‐rate’ functional analysis produced interpretable results for all three participants. Two of the three participants were available for the evaluation of treatments based on their functional analysis results. Function‐based treatments suppressed rates of problem behavior for both participants. Copyright © 2004 John Wiley & Sons, Ltd.
Contingent electric shock (SIBIS) and a conditioned punisher eliminate severe head banging in a preschool child
Authors: Salvy Sarah‐Jeanne , Mulick James A. , Butter Eric , Bartlett Rita Kahng , Linscheid Thomas R.
Published: March 2004

We report a case in which a Self‐Injurious Behavior Inhibiting System (SIBIS) device and a conditioned punisher were utilized to decrease and maintain suppression of severe head hitting/banging in a preschool child. After an experimental evaluation conducted at the hospital, SIBIS was implemented at home. The originality of this particular SIBIS case study is that programmed and systematic effort at establishing conditioned punishment was included in the intervention. Results indicate that a zero‐level response was rapidly reached, and that the conditioned punisher (i.e. verbal prompt + movement towards the place where SIBIS was kept) was sufficient to maintain treatment effects. Continuous assessment after treatment and formal observation session at 7 months follow‐up revealed that SIBIS could be removed from the natural environment of the child while maintaining a therapeutic effect. These results were interpreted as the effects of the explicit pairing between the delivery of electric stimulations and previously neutral stimuli, which were initially ineffective to elicit any response, or to suppress SIB. Close and extended monitoring during and after treatment failed to reveal the presence of negative side effects associated with SIBIS, whereas a number of positive effects were observed. Copyright © 2004 John Wiley & Sons, Ltd.
Computational Approaches to Activity in Rhodium‐Catalysed Hydroformylation
Authors: Gleich Dieter , Hutter Jürg
Published: March 2004

In this theoretical study on rhodium‐catalysed hydroformylation we examine an unmodified hydridorhodium(I) carbonyl system a together with three variants modified by the model phosphane ligands PF3 (system b), PH3 (system c) and PMe3 (system d), which show increasing basicity on the Tolman χ parameter scale. The olefinic substrate for all systems is ethene. Based on the dissociative hydroformylation mechanism, static and dynamic quantum‐mechanical approaches are made for preequilibria and the whole catalytic cycle. Agreement with experimental results was achieved with regard to the predominance of phosphane monocoordination in systems b–d, different sensitivity of unmodified and modified systems towards hydrogen pressure and the early location of the rate‐determining step. Neither the catalytic cycle as a whole nor olefin insertion as an important selectivity‐determining step gives a clear picture of activity differences among a–d. However, the crucial first catalytic step, association of ethene to the active species [HRhL3] (L=CO, PR3), may play the key role in the experimentally observed higher activity of a and systems with less basic phosphane ligands modelled by b.
Noncentrosymmetric Organic Solids with Very Strong Harmonic Generation Response
Authors: Zhao Hong , Li Yong‐Hua , Wang Xi‐Sen , Qu Zhi‐Rong , Wang Li‐Zhong , Xiong Ren‐Gen , Abrahams Brendan F. , Xue Ziling
Published: March 2004

The molten reaction of 2‐naphthol, 4‐(aminomethyl)pyridine, and 4‐pyridinecarboxaldehyde at about 180 °C yields trans‐2,3‐dihydro‐2,3‐di(4′‐pyridyl)benzo[e]indole (1) which possesses two chiral centers, rather than an expected Betti‐type reaction product with only one chiral carbon center. The same reactions, using 3‐pyridinecarboxaldehyde, 4‐cyanobenzaldehyde, or 3‐ cyanobenzaldehyde instead of 4‐pyridinecarboxaldehyde produce the related compounds trans‐2,3‐dihydro‐2‐(4′‐pyridyl)‐3‐(3′′‐pyridyl)benzo[e]indole (2), trans‐2,3‐dihydro‐2‐(4′‐pyridyl)‐3‐(4′′‐cyanophenyl)benzo[e]indole (3), and trans‐2,3‐dihydro‐2‐(4′‐pyridyl)‐3‐(3′′‐cyanophenyl)benzo[e]indole (4), respectively. This reaction proceeds with a high degree of stereoselectivity with a trans/cis ratio of about 98:2 at elevated temperature. Compounds 1, 2, and 4 crystallize in a noncentrosymmetric space group (Pca21, Pca21, and Cc), while compound 3 has a chiral space group (P21). These successfully acentric packing arrangements are probably due to the molecule bearing both two chiral centers and potential hydrogen‐bonding groups. Furthermore, the reaction of racemic 6‐hydroxy‐2′‐methyl‐2‐naphthaleneacetic acid with ethyl‐2‐cyano‐1‐(4′‐pyridyl)acrylic acetate in the presence of piperidine gives 1‐pyridyl‐2‐ethoxycarbonyl‐3‐amino‐1H‐naphtho[2,1‐b]pyran‐2′‐methylacetic acid (5), which likewise crystallizes in a chiral space group. All of compounds are second harmonic generation (SHG) active, and have a very strong SHG response approximately about 8.0, 5.0, 12.0, 6.0, and 1.4 (for 1–5 compounds) times that of urea. Ferroelectric property measurements indicate that compounds 1, 2, 4, and 5 may display ferroelectric behavior.
Kinetic Precipitation of Solution‐Phase Polyoxomolybdate Followed by Transmission Electron Microscopy: A Window to Solution‐Phase Nanostructure
Authors: Zhu Yan , Cammers‐Goodwin Arthur , Zhao Bin , Dozier Alan , Dickey Elizabeth C.
Published: March 2004

This study aimed to elucidate the structural nature of the polydisperse, nanoscopic components in the solution and the solid states of partially reduced polyoxomolybdate derived from the {Mo132} keplerate, {(Mo)Mo5}12‐{Mo2 acetate}30. Designer tripodal hexamine‐tris‐crown ethers and nanoscopic molybdate coprecipitated from aqueous solution. These microcrystalline solids distributed particle radii between 2–30 nm as assayed by transmission electron microscopy (TEM). The solid materials and their particle size distributions were snap shots of the solution phase. The mother liquor of the preparation of the {Mo132} keplerate after three days revealed large species (r=20–30 nm) in the coprecipitate, whereas {Mo132} keplerate redissolved in water revealed small species (3–7 nm) in the coprecipitate. Nanoparticles of coprecipitate were more stable than solids derived solely from partially reduced molybdate. The TEM features of all material analyzed lacked facets on the nanometer length scale; however, the structures diffracted electrons and appeared to be defect‐free as evidenced by Moiré patterns in the TEM images. Moiré patterns and size‐invariant optical densities of the features in the micrographs suggested that the molybdate nanoparticles were vesicular.
The Advantage of Being Virtual—Target‐Induced Adaptation and Selection in Dynamic Combinatorial Libraries
Authors: Severin Kay
Published: March 2004

Numerical simulations are presented that describe the adaptive behavior of simple dynamic combinatorial libraries (DCLs) upon addition of a target. By studying the effect of various parameters such as the network topology, the initial concentrations, the association constants, and the binding affinities, general characteristics of such systems were derived. It is shown that the adaptation may lead to the amplification of molecules with a high affinity to the target, but only for specific boundary conditions. Furthermore, it is demonstrated that the selection process can be refined by using an evolutionary approach. These results are of importance for the design of selection experiments with DCLs.
Crystallization‐Induced Asymmetric Transformation of Chiral‐at‐metal Ruthenium(II) Complexes Bearing Achiral Ligands
Authors: Hamelin Olivier , Pécaut Jacques , Fontecave Marc
Published: March 2004

Recently, we observed that the enantiopure Λ form of the tributylammonium salt of the chiral anion tris[tetrachlorobenzene‐1,2‐bis(olato)]phosphate, also named Trisphat, was able to induce an efficient resolution of a Δ,Λ racemic mixture of cis‐[Ru(dmp)2(NCCH3)2](PF6)2 (dmp=2,9‐dimethyl‐1,10‐phenanthroline) due to the spontaneous and selective precipitation of the heterochiral pair [Δ‐Ru(dmp)2(CH3CN)2][Λ‐Trisphat]2. We report here that the combination of such a stereoselective precipitation process and irradiation results in the quantitative conversion of the initial [Ru(dmp)2(NCCH3)2]2+ racemate into only one of the two enantiomers. This is the first example in inorganic chemistry of an asymmetric transformation that leads to a chiral complex with no chiral ligand. Finally, three new racemic ruthenium bis(diimine) complexes, namely [Ru(dmp)2(NCCH3)Py](PF6)2 (Py=pyridine), [Ru(dmp)2(1,3‐diaminopropane)](PF6)2, and [Ru(dmp)2(ethylenediamine)](PF6)2 were synthesized. For all of them, crystallization‐induced asymmetric transformation proved to be an efficient way of obtaining the corresponding optically active chiral‐at‐metal complexes in high yields and with excellent stereoselectivities.
Greco‐Roman thought about cancer
Authors: Hajdu Steven I.
Published: March 2004

Drawing on his broad‐based international and historical perspectives in oncology while incorporating original source materials from his own large personal collection of antiquarian books concerning the area of medical history, Dr. Hajdu has kindly volunteered to author a new series on the history of oncology. We hope you enjoy his first article in this issue of Cancer.
Peripheral olfactory ensheathing cells reduce scar and cavity formation and promote regeneration after spinal cord injury
Authors: Ramer Leanne M. , Au Edmund , Richter Miranda W. , Liu Jie , Tetzlaff Wolfram , Roskams A. Jane
Published: March 2004

Bridging of a lesion site and minimizing local damage to create an environment permissive for regeneration are both primary components of a successful strategy to repair spinal cord injury (SCI). Olfactory ensheathing cells (OECs) are prime candidates for autologous transplantation to bridge this gap, but little is known currently about their mechanism of action. In addition, OECs from the accessible lamina propria (LP) of the olfactory mucosa are a more viable source in humans but have yet to be tested for their ability to promote regeneration in established SCI models. Here, mouse LP‐OECs expressing green fluorescent protein (GFP) transplanted directly into both rat and mouse dorsolateral spinal cord lesion sites demonstrate limited migration but interact with host astrocytes to develop a new transitional zone at the lesion border. LP‐OECs also promote extensive migration of host Schwann cells into the central nervous system repair zone and stimulate angiogenesis to provide a biological scaffold for repair. This novel environment created by transplanted and host glia within the spinal cord inhibits cavity and scar formation and promotes extensive sprouting of multiple sensory and motor axons into and through the lesion site. Sixty days after rat SCI, serotonin‐ and tyrosine hydroxylase‐positive axons sprouted across the lesion into the distal cord, although axotomized rubrospinal axons did not. Thus, even in a xenotransplant paradigm, LP‐OECs work collaboratively with host glial cells to create an environment to ameliorate local damage and simultaneously promote a regenerative response in multiple axonal populations. J. Comp. Neurol. 473:1–15, 2004. © 2004 Wiley‐Liss, Inc.
Androgen receptor immunoreactivity in skeletal muscle: Enrichment at the neuromuscular junction
Authors: Monks Douglas Ashley , O'Bryant Erin Louise , Jordan Cynthia Lee
Published: March 2004

Potential cellular targets of androgen action within skeletal muscle of the rat were determined by comparing the cellular distribution of androgen receptor (AR)‐positive nuclei in the highly androgen‐responsive levator ani (LA) muscle with that of the relatively androgen‐unresponsive extensor digitorum longus (EDL) muscle. We found that androgen responsiveness correlates with AR expression in muscle fibers and not in fibroblasts. Results indicate that a much higher percentage of myonuclei in the LA are AR+ than in the EDL (74% vs. 7%), correlating with differences in androgen responsiveness. Both muscles contain an equivalent proportion of AR+ fibroblasts (∼62%). AR+ nuclei were not observed in terminal Schwann cells in either muscle. These results suggest that ARs within LA muscle fibers mediate the androgen‐dependent survival and growth of the LA muscle and its motoneurons. We also observed an unexpected enrichment of AR+ myonuclei and fibroblasts proximate to neuromuscular junctions, suggesting that ARs at muscle synapses may selectively regulate synapse‐specific genes important for the survival and growth of motoneurons. Although castration reduced the proportion of AR+ fibroblasts in both muscles, the proportion of AR+ myonuclei was reduced only in the LA. As expected, testosterone treatment prevented these effects of castration but, unexpectedly, increased the proportion of AR+ myonuclei in the EDL to above normal. These results suggest that how AR expression in skeletal muscle is influenced by androgens depends not only on the particular muscle but on the particular cell type within that muscle. J. Comp. Neurol. 473:59–72, 2004. © 2004 Wiley‐Liss, Inc.
Iminohydroxamato Early and Late Transition Metal Halide Complexes − New Precatalysts for Aluminoxane‐Cocatalyzed Olefin Insertion Polymerization
Authors: Krajete Alexander , Steiner Georg , Kopacka Holger , Ongania Karl‐Hans , Wurst Klaus , Kristen Marc O. , Preishuber‐Pflügl Peter , Bildstein Benno
Published: March 2004

We report on new families of non‐metallocene metal precatalysts for olefin polymerization with titanium, zirconium, vanadium and nickel as the active metal sites. The novel ligand design concept is based on iminohydroxamic acids and their derivatives as the principal chelating units. Various anionic and neutral [N,O] and [N,N] ligand systems are easily accessible by a modular synthetic sequence of imidoyl chlorides with substituted hydroxylamines or hydrazines, respectively. Steric protection of the metal coordination site, a necessary requirement for suppression of chain termination pathways of non‐metallocene catalysts, is brought about by bulky aryl substituents on the imino nitrogen atoms. Crystal structures of some of the hydroxamato ligands reveal interesting intermolecular hydrogen‐bridged structures, whereas in the solid‐state structure of one titanium precatalyst a five‐membered chelate was observed, in line with the design principle of these systems. Preliminary ethylene polymerization studies with methylaluminoxane‐activated metal complexes (M = Ti, Zr, V, Ni) show that the most active systems are [N,O]NiBr2 catalysts containing neutral O‐alkyl iminohydroxamate ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Carboxy Ester Hydrolysis Promoted by a Dicopper(II) Macrocyclic Polyamine Complex with Hydroxypropyl Pendant Groups
Authors: Huang Jin , Li Shu‐An , Li Dong‐Feng , Yang De‐Xi , Sun Wei‐Yin , Tang Wen‐Xia
Published: March 2004

A dinuclear CuII complex containing a hexaaza macrocyclic ligand bearing two 2‐hydroxypropyl pendants, 3,6,9,16,19,22‐hexaaza‐6,19‐bis(2‐hydroxypropyl)tricyclo[22.2.2.211,14]triaconta‐1,11,13,24,27,29‐hexaene (L), was synthesized. The title complex [Cu2(H−2L)Cl2]·6.5H2O was isolated as a blue crystal, orthorhombic, space group Fddd, with a = 16.4581(12), b = 32.248(2), c = 35.830(2) Å, V = 19017(2) Å3, Z = 16, R1 = 0.0690, and wR2 = 0.1546 [I > 2σ(I)]. The protonation constants of Cu2L were determined by potentiometric titration, and it was found that the alcoholic hydroxypropyl group of the complex Cu2L exhibits low pKa values of pKa1 = 7.31, pKa2 = 7.83 at 25 °C. The hydrolysis kinetics of 4‐nitrophenyl acetate (NA) promoted by the title complex have also been studied. The pH‐rate profile for Cu2L gave a sigmoidal curve and showed a second‐order rate constant of 0.39 ± 0.02 M−1 s−1 in 10% CH3CN/H2O(v/v), which is greater than that of the dinuclear CuII complex formed by a hexaaza macrocycle without pendants. The reason for the higher catalytic activity of the title complex is discussed. We found that the volume of nucleophile RO− can effect the hydrolysis of the carboxy ester, the nucleophilicity of RO− and the Lewis acidity of the metal macrocycle also affect the carboxy ester hydrolysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Unusual Two‐Dimensional Nickel(II) Complexes Based on [Ni(dien)]2+ and [M(CN)4]2− Building Blocks (M = Ni, Pd and Pt) − Synthesis, Structural Diversity and Magnetic Properties
Authors: Muga Iñaki , Gutiérrez‐Zorrilla Juan M. , Vitoria Pablo , Román Pascual , Lezama Luis , Beitia Javier I.
Published: March 2004

Three novel polymeric compounds [Ni(dien)Ni(CN)4]n(H2O)n (1), [Ni(dien)Pd(CN)4]n (2), and [Ni(dien)Pt(CN)4]n (3) were synthesised by reaction of [{Ni(dien)(H2O)}2(μ‐ox)](PF6)2 with [M(CN)4]2− (M = Ni, Pd, Pt) in aqueous solution. The structure of these compounds contains two [Ni(dien)]2+ cationic units bridged by two [M(CN)4]2− anions in a cis fashion, generating a square‐shaped [Ni2−M2] metal core. The different linking modes between the cores afford a 2D bilayer with encapsulated water in compound 1 and corrugated layers in compounds 2 and 3. These coordination modes are compared to the different bridging modes of tetracyanometalate‐containing compounds retrieved from the CSD database. The three compounds present a very weak antiferromagnetic coupling between the octahedrally coordinated NiII ions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
One‐Pot Synthesis of 1,6‐Diiodo‐2,3,4,5‐tetracarba‐nido‐hexaboranes(6) and Mechanistic Studies on the Reaction System Alkynes/BI3/NaK2.8
Authors: Nie Yong , Schwiegk Stefan , Pritzkow Hans , Siebert Walter
Published: March 2004

Attempts to prepare the tetracarba‐nido‐octaborane(8) derivative (EtC)4(BI)4 (4) by treatment of 3‐hexyne with BI3 (2 equiv.) and NaK2.8 led to 2,3,4,5‐tetraethyl‐1,6‐diiodo‐2,3,4,5‐tetracarba‐nido‐hexaborane(6) (2a) as the predominant product with trace quantities of 4 as well as 2,3‐diethyl‐1,4,5,6,7‐pentaiodo‐2,3‐dicarba‐closo‐heptaborane(7) (5). Starting at −78 °C, reactions of 3‐hexyne, 2‐butyne or diphenylacetylene, respectively, with BI3 (1 equiv.) and NaK2.8 afforded the corresponding 1,6‐diiodo‐2,3,4,5‐tetracarba‐nido‐hexaboranes(6) 2a−c as the single carborane products. In the cases of 3‐hexyne and diphenylacetylene, the formation of hexaorganylbenzene derivatives was also detected. To confirm the formation of 4 and 5, the independent dehalogenation of cis‐3,4‐bis(diiodoboryl)‐3‐hexene (3) with NaK2.8 has been studied, which indeed affords 4 and 5, with the former being the predominant product. A mechanism for the formation of 2a has been proposed, which involves iodoboration of the alkyne to give the borylalkene 1a. This is followed by deiodination, presumably yielding the iodoborirene derivative 7, which easily dimerizes to form the 1,4‐diboracyclo‐2,5‐hexadiene derivative 8. Subsequent rearrangement leads to the final C4B2‐nido‐carborane 2a. To determine the stereochemistry of 1a, its pyridine adduct 9 (and the isomer 9′) and catechol derivative 10 (and the isomer 10′), and the diisopropylamino derivative 11 have also been prepared. The new compounds have been characterized by MS and NMR spectroscopy, and the structures of 2a, 3, 9 and 9′ were confirmed by single‐crystal X‐ray analyses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Nucleobase Oxidation of DNA by (Terpyridyl)chromium(III) Derivatives
Authors: Vaidyanathan Vaidyanathan Ganesan , Nair Balachandran Unni
Published: March 2004

The chromium(III) complexes [Cr(ttpy)2](ClO4)3 (1) and [Cr(Brphtpy)2](ClO4)3 (2), containing the terpyridyl derivatives ttpy and Brphtpy [ttpy = p‐tolylterpyridine; Brphtpy = (p‐bromophenyl)terpyridine] have been synthesized and characterized by ESI‐MS, electronic spectroscopy, and cyclic voltammetry. Absorption titration and thermal denaturation studies reveal that both complexes are moderate binders of calf thymus DNA (CT DNA), while viscosity measurements show that they bind with partial intercalation. Binding of the two chromium complexes to DNA and mononucleotides dGMP, dAMP, dCMP, and dTMP decreases the emission intensity of complex 2. However, the emission intensity of complex 1 is quenched only by DNA and the nucleotides dGMP and dAMP. Excited state potentials of both 1 and 2 have been estimated to be 1.65 and 1.85 V vs. NHE. These results demonstrate that 2 is a stronger photooxidant than 1, and other (diimine)chromium complexes, and that it can oxidize nucleobases. The photonuclease activity of 1 and 2 has been confirmed by gel electrophoresis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Theoretical Investigation of Group 4 Constrained‐Geometry Complexes Featuring Phosphazene and Phosphinimido Arms
Authors: Truflandier Lionel , Marsden Colin J. , Freund Christelle , Martin‐Vaca Blanca , Bourissou Didier
Published: March 2004

Density functional calculations are reported for the neutral and cationic forms of the “CpPN” zirconium complexes E and F featuring a phosphazene and phosphinimido pendant arm, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Activation of H2 and CO by Sulfur‐Rich Nickel Model Complexes for [NiFe] Hydrogenases and CO Dehydrogenases
Authors: Sellmann Dieter , Prakash Raju , Heinemann Frank W.
Published: March 2004

Reactions of the trinuclear complexes [Ni(RS3)]3 [HS32− = bis(2‐mercaptophenyl)sulfide(2−) (1a) or siS32− = bis(2‐mercapto‐3‐trimethylsilylphenyl)sulfide(2−) (1b)] with nucleophiles L (L = NHPnPr3, NHPCy3, NHSPh2, PnPr3) afforded the corresponding mononuclear complexes [Ni(L)(RS3)] [R = si = SiMe3; L = NHPnPr3 (2b); L = NHPCy3 (3a,b); L = NHSPh2 (4a,b); L = PnPr3 (5a)]. X‐ray structural determinations showed that 2b, 3a, 3b, 4a, and 5a exhibit tetrahedrally distorted planar [Ni(L)(RS3)] fragments. Complex 2b dimerizes through intermolecular N−H···N hydrogen bonding. In contrast to 2b, complexes 3a and 4a exhibit intramolecular hydrogen bonds between thiol groups and NH protons. Complexes 2−4 possess weakly acidic NH protons and undergo D+/NH exchange reactions with D2O or CD3OD. Complexes 2−4 and [Ni(StBu)(RS3)]− (9a,b) also catalyze D2/H+ exchange in [D8]THF/H2O under an elevated pressure of D2 (18 bar), as confirmed by 1H NMR spectroscopy. It is proposed that D2 heterolysis is achieved through attack of the Lewis‐acidic nickel centers and the Brönsted‐basic sulfur atoms at an η2‐D2 ligand. Complexes 9a and 9b are the first sulfur‐only nickel complexes that enable the modeling of the [NiFe] hydrogenase catalyzed D2/H+ exchange reaction. Evidence for labile five‐coordinate [Ni(CO)(L)(RS3)] has been found in the reaction between [Ni(L)(RS3)] complexes and CO. The CO adducts of complexes with nitrogenous ligands L such as N3−, NHPR3 (R = nPr3, Cy3), or NHSPh2 showed rapid consecutive reactions. The reaction between Et4N[Ni(N3)(siS3)] (8b) and CO gave Et4N[Ni(NCO)(siS3)] (10b), whereas reactions between 2−4 and CO afforded only 1a or 1b. Mechanisms are suggested which have the formation of reactive five‐coordinated [Ni(CO)(L)(RS3)] intermediates in common. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Switch of the Lowest Excited‐States of Terpyridylplatinum(II) Acetylide Complexes Bearing Amino or Azacrown Moieties by Proton and Cations
Authors: Yang Qing‐Zheng , Tong Qing‐Xiao , Wu Li‐Zhu , Wu Zi‐Xin , Zhang Li‐Ping , Tung Chen‐Ho
Published: March 2004

The investigation of the synthesis and unique photophysical properties of two terpyridylplatinum(II) acetylide complexes [Pt(terpy)(C≡CC6H4‐4‐R)] where terpy is 2,2′:6′,2′′‐terpyridyl and R = N(CH3)2(1) orN‐15‐monoazacrown‐5 (2) has been carried out. These complexes exhibit an absorption band in the region of 460−650 nm in neutral or basic solution that corresponds to a ligand‐to‐ligand charge transfer (LLCT) transition from the amino‐substituted acetylide to the terpyridyl acceptor. In acidic solutions the complexes show the lowest‐energy absorption band at 380−500 nm, which is assignable to a dπ(Pt)→π*(terpy) metal‐to‐ligand charge transfer (MLCT) transition. In acidic media the complexes are emissive with quantum yields of 1 × 10−3to 2 × 10−3, and lifetimes of 20−50 ns. Compound2may complex metal cations through its azacrown ether moiety. For Na+, Ba2+, Ca2+and Mg2+, a 1:1 binding mode with logKs of 2.52 to 4.18 was observed. As in the case of acidic solution, the cation‐bound complex also features the lowest‐lying MLCT excited state. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Differential mutagen sensitivity of peripheral blood lymphocytes from smokers and nonsmokers: Effect of human cytomegalovirus infection
Authors: Albrecht Thomas , Deng Cheng Zong , Abdel‐Rahman Sherif Z. , Fons Michael , Cinciripini Paul , El‐Zein Randa A.
Published: March 2004

We used the mutagen sensitivity assay to test the hypothesis that human cytomegalovirus (HCMV) infection modifies the sensitivity of cells to genetic damage from genotoxic agents. Chromosome aberration (CA) frequency in peripheral blood lymphocytes (PBLs) from 20 smokers who were matched with 20 nonsmokers by age (± 5 years), sex, and ethnicity was evaluated following in vitro exposure to bleomycin and/or HCMV infection. Bleomycin induced significant (P < 0.05) concentration‐dependent increases in the frequency of aberrant cells, chromatid‐type damage (breaks), and chromosome‐type aberrations (deletions, rearrangements) in PBLs. The baseline (background) CA frequency was similar in both smokers and nonsmokers. Significantly higher frequencies of aberrant cells (P < 0.05) were observed in PBLs from smokers compared to nonsmokers at all bleomycin concentrations tested (10, 30 and 100 μg/ml). Infection of PBLs with HCMV induced a significant (P < 0.05) twofold increase in the frequency of CA (primarily chromatid breaks) in PBLs, regardless of the smoking status. PBLs from smokers and nonsmokers infected with HCMV prior to challenge with bleomycin demonstrated significant (P < 0.05) concentration‐dependent increases in the levels of aberrant cells, chromatid‐type damage (breaks), and chromosome‐type aberrations (deletions, rearrangements) compared to noninfected cells challenged with bleomycin. The frequency of induced CA was consistently higher for PBLs derived from smokers relative to nonsmokers (P = 0.06 and 0.002). These data indicate that, individually, both smoking and HCMV infection significantly enhance the sensitivity of PBLs to bleomycin‐induced genetic damage. More importantly, the data also suggest that smoking and HCMV infection interact synergistically to enhance the sensitivity of PBLs to such damage. Environ. Mol. Mutagen. 43:169–178, 2004. © 2004 Wiley‐Liss, Inc.