bluuebunny/crossref_metadata_2025 huggingface dataset:
Humic colloid mediated transport of tetravalent actinides and technetium
Authors: Artinger Robert , Buckau Gunnar , Zeh P. , Geraedts K. , Vancluysen J. , Maes A. , Kim Jae-Il
Published: December 2003

The humic colloid mediated transport of tetravalent actinide and technetium ions is discussed. Numerous published and new results are used from comparable experimental systems and conditions. The results originate from investigations on two humic rich Gorleben groundwater/sediment systems under near-natural conditions. The conditioning time between groundwater and radionuclides vary from few minutes to four years. The migration time (residence time in the column) is varied from four hours to three days. The concentration of radionuclides added is varied between about 10-12and 10-4mol/L. Humic colloids in natural groundwater contain trace metal ions in varying concentrations. In addition to studying the behavior of radionuclides added to the groundwater in the laboratory, the dissociation behavior of these natural tetravalent trace metal ions is studied by scavenging dissociating ions with a cation exchanger. The results show a kinetic behavior of the trace metal ion interaction as frequently reported in the literature,i.e.with increasing contact time, slow dissociation modes are progressively populated resulting in an enhanced radionuclide transport. The strong dependency of the radionuclide transport on the radionuclide concentration shows that humic colloid mediated transport may be overestimated if radionuclide concentrations used in laboratory studies are too high. Dissociation of the natural inventory of humic associated tetravalent trace metal ions proceeds with a kinetics comparable to the radionuclides added. This, however, is only observed for a small portion of the inventory and extrapolation beyond the observation range is not permissible. Therefore, the key question for application to predictive modeling of the mobility of tetravalent radionuclides in natural groundwater is if the behavior of the natural trace element inventory is applicable or the behavior of radionuclides added in laboratory studies.
Study of hafnium complexes by time differential perturbed angular correlation technique
Authors: Das S. K. , Saha S. K.
Published: December 2003

Complexation of hafnium with two ligands viz. diethylene triamine pentaacetic acid (DTPA) and its dimethyl ester derivative (DMDTPA) has been studied by using time differential perturbed angular correlation (TDPAC) technique. Nuclear quadrupole coupling constant (ν
Q), asymmetry of the EFG (η) and the frequency distribution (δ) for these complexes have been obtained. Square antiprism structures have been suggested for these complexes using these parameters. A systematic trend of the ν
Q has been observed in these and other hafnium complexes with similar ligands and has been explained in terms of the electronegativity of the donor atoms in the ligands.
Sr3Ga4O9 – a strontium gallate with a new type of tetrahedral layer structure
Authors: Kahlenberg V. , Parise J. B.
Published: December 2003

Synthetic strontium gallate Sr3Ga4O9 is triclinic, space group P1̅ (a = 6.7490(9)Å, b = 8.0494(12)Å, c = 9.7295(15)Å, α = 85.01(2)º, β = 72.71(2)º, γ = 74.24(2)º, V = 485.7(3)Å3, Z = 2, D
calc = 4.69 g·cm-3). The structure was solved by direct methods using 2656 unique reflections and refined to a residual of R1 = 0.042 (146 parameters). The compound belongs to the group of tetrahedral single layer structures. Individual sheets are parallel to (100), thus producing a prominent cleavage. The stepped layers can be described as being built by the condensation of six tetrahedra-wide bands. The bands in turn consist of two open branched dreier single chains connected via common corners and they contain tertiary and quaternary tetrahedra Q3 and Q4 in the ratio 1:1. The stacking of the layers containing four-, six- and eight-membered rings results in a three-dimensional structure in which the strontium cations reside in the voids between the layers and are coordinated by six to seven oxygen neighbors.
Crystal structure, magnetic properties and band gap measurements of NdTe2-

x
(x=0.11(1))
Authors: Stöwe K.
Published: December 2003

As for the homologous La, Ce and Pr compounds, the X-ray diffraction single-crystal structure analysis of NdTe2 (prepared by chemical vapor transport reactions in the presence of traces of iodine) also revealed superstructure reflections, but indicating a (3x4x2) supercell of the basic anti-Fe2As type instead of a (2x2x1) supercell as for LaTe2 or a (2x2x2) supercell as for CeTe2 and PrTe2. NdTe2 crystallizes orthorhombic with the lattice parameters a = 1328.9(1) pm, b = 1767.7(2) pm and c = 1806.9(2) pm (Z = 48) in space group Amm2. Analysis by ICP-OES as well as density measurements revealed a nonstoichiometric composition (ICP-OES: NdTe1.90(2); X-ray diffraction: NdTe1.89(1)), whereas the other compounds of this series, LaTe2, CeTe2 and PrTe2, showed no defects in the tellurium sublattice. Compared to the basic anti-Fe2As structure type, the differences of this new structure lie entirely in the topology of the polyanionic square nets. Due to the presence of distortions and defects, the sheets may be regarded as revealing several different canonical entities, which are assumed by emphasizing interatomic distances below a certain limit (305 pm). These entities are [Te2] dimers, square-shaped [Te8] rings and, to a small amount, even more complicated fragments. All in all the distortions lead to a semiconducting compound (band gap ΔE = 0.14 eV), which obeys the Curie-Weiss law and reveals even at T = 2 K no indications for a magnetic ordering.
Electron crystallography of the polymethylene chain. 5. Three-dimensional structure of a Fischer-Tropsch wax
Authors: Dorset Douglas L.
Published: December 2003

The crystal structure of a Fischer-Tropsch wax, Shell Callista 158, has bee determined in three dimensions from electron diffractio intensity data. Although there is an orthorhombic layer arrangement with apparent dimensions, a = 7.42, b = 4.96, c = 94.50 Å, true lamellae cannot form, due to a ‘nematocrystalline’ arrangement of very long chain components,generating a continuous chain direction through adjacent chain layer clusters. The structure is actually a superlattice of the Pnam cell observed for high molecular weight polyethylene.
Mortality from cardiovascular disease in relation to magnetic field exposure: Findings from a study of UK electricity generation and transmission workers, 1973–1997
Authors: Sorahan Tom , Nichols Linda
Published: December 2003

Background

Experimental and epidemiological studies have indicated that magnetic field exposure might influence heart rate variability and consequent risks of arrhythmia related deaths.

Methods

The mortality experience of a cohort of 83,997 employees of the former Central Electricity Generating Board (CEGB) of England and Wales was investigated for the period 1973–1997. Cohort members were employed for at least 6 months from 1973 to 1982. Computerized work histories were available for 79,972 study subjects for the period 1971–1993. Detailed calculations had been performed by others to enable a novel assessment to be made of exposures to magnetic fields. Two analytical approaches were used, indirect standardization (n = 83,997) and Poisson regression (n = 79,972).

Results

Based on serial mortality rates for England and Wales, deaths from four categories of cardiovascular disease were below expectation: arrhythmia‐related disease (ICD‐9 426‐7), observed (obs) 32, expected (exp) 43.5, standardized mortality ratio (SMR) 74; acute myocardial infarction (ICD‐9 410), obs 3,320, exp 3878.3, SMR 86; atherosclerosis (ICD‐9 440), obs 25, exp 39.2, SMR 64; chronic/sub‐acute coronary disease (ICD‐9 411‐414), obs 1,552, exp 2021.7, SMR 77). No statistically significant trends were shown for risks of any of these four disease groupings to increase either with lifetime cumulative exposure to magnetic fields or with such exposures received in the most recent 5 years.

Conclusions

There are no discernible excess risks of mortality from cardiovascular diseases as a consequence of occupational exposure to magnetic fields in UK electricity generation and transmission workers. Am. J. Ind. Med. 45:93–102, 2004. © 2003 Wiley‐Liss, Inc.
Relationships between certain individual characteristics and occupational injuries for various jobs in the construction industry: A case‐control study
Authors: Chau Nearkasen , Mur Jean‐Marie , Benamghar Lahoucine , Siegfried Christian , Dangelzer Jean‐Louis , Français Martine , Jacquin Régis , Sourdot Alain
Published: December 2003

Background

There is little published about the role of individual characteristics in occupational injuries. Construction workers have a high rate of injury; we assessed 11 personal characteristics in this professional sector.

Methods

A case‐control study was conducted on 880 male workers who had had at least one occupational injury during a 2‐year period and 880 controls. A questionnaire was administered by an occupational physician. Statistical analysis was made via logistic regression method.

Results

Young age (<30 years), sleep disorders and current smoker influenced all the injuries combined. Sleep disorders and young age were common risk factors for several jobs. Physical disabilities and no sporting activity had a role in masons, and 5 years or less in present job in plumbers and electricians only. Sleep disorders influenced both the injuries with and without hospitalization; young age, current smoker, and physical disability influenced those without hospitalization only.

Conclusions

Young age, sleep disorders, smoking, disabilities, sporting activity, and experience influenced the occupational injuries. The risk for each worker depended on his job. Occupational physicians could inform the workers of these risks and encourage them to take remedial action. Am. J. Ind. Med. 45:84–92, 2004. © 2003 Wiley‐Liss, Inc.
A survey on exposure level, health status, and biomarkers in workers exposed to 1‐bromopropane
Authors: Ichihara Gaku , Li Weihua , Ding Xuncheng , Peng Simeng , Yu Xiaozhong , Shibata Eiji , Yamada Tetsuya , Wang Hailan , Itohara Seiichiro , Kanno Seiichiro , Sakai Kiyoshi , Ito Hidenori , Kanefusa Kato , Takeuchi Yasuhiro
Published: December 2003

Background

The aim of this study was to evaluate the health effects of exposure mainly to 1‐bromopropane, which is an alternative to ozone‐depleting solvents, and to establish biomarkers for assessing 1‐bromopropane exposure.

Methods

Twenty‐four female and 13 male workers of a 1‐bromopropane‐factory were interviewed, and their urine and blood samples were collected. Measured parameters included 1‐bromopropane levels in the factory, as well as individual exposure levels, urinary 1‐bromopropane levels, enzymatic activity and M subunit's concentration of serum creatine kinase (CK).

Results

Frequent symptoms reported by workers exposed to 1‐bromopropane were nose, throat, and eyes irritation or malaise and/or headache. Urinary 1‐bromopropane levels correlated significantly with individual exposure levels, but enzymatic activity or CK–M subunit did not.

Conclusions

The symptoms suggested irritation of the mucous membrane and possible adverse effects on the central nervous system. There were no severe chronic symptoms suggestive of neurological damage in workers exposed to less than 170 ppm. Urinary 1‐bromopropane level may be a good indicator of exposure. Am. J. Ind. Med. 45:63–75, 2004. © 2003 Wiley‐Liss, Inc.
Occupational fatalities of Hispanic construction workers from 1992 to 2000
Authors: Dong Xiuwen , Platner James W.
Published: December 2003

Background

Hispanic construction employment has dramatically increased, yet published data on occupational risk is lacking.

Methods

Data from the Census of Fatal Occupational Injuries (CFOI) and current population survey (CPS) were examined from 1992 to 2000. Fatality rate, relative risk (RR), and risk index were calculated using CFOI fatality data and CPS data on hours worked, adjusted to full‐time‐equivalents (FTE). Data between 1996 and 2000 were combined to allow reliable comparisons of age and occupational groups. RR and 95% confidence intervals were calculated.

Results

In 2000, Hispanics constituted less than 16% of the construction workforce yet suffered 23.5% of fatal injuries. RRs were: helpers, construction trades, 2.31 (95% CI: 1.41–3.80); roofers 1.77 (95% CI: 1.38–2.28); carpenters 1.39 (95% CI: 1.08–1.79); and construction laborers 1.31 (95% CI: 1.17–1.46).

Conclusions

Hispanic construction workers consistently faced higher RRs, for every year from 1992 to 2000 and for every age group. In 2000, Hispanic construction workers were nearly twice (1.84, 95% CI: 1.60–2.10) as likely to be killed by occupational injuries as their non‐Hispanic counterparts. Am. J. Ind. Med. 45:45–54, 2004. © 2003 Wiley‐Liss, Inc.
Exposure variability: Concepts and applications in occupational epidemiology
Authors: Loomis Dana , Kromhout Hans
Published: December 2003

Background

Standard approaches to assessing exposures for epidemiologic studies tend to concentrate resources on obtaining detailed data for each study participant at the expense of characterizing within‐person variability.

Methods

This paper presents some basic, generalizeable concepts concerning exposure and its variability, describes methods that can be used to analyze, describe, and understand that variability, and reviews related implications for the design and interpretation of epidemiologic studies.

Results and Conclusions

Insufficient attention to the balance of within‐ and between‐person variation in exposure can reduce the efficiency of measurement efforts and attenuate estimates of exposure‐disease association. Exposure variability should consequently be considered carefully in the planning, analysis, and interpretation of epidemiologic studies. Greater attention to these matters can lead to more meaningful characterization of exposure itself, and, most importantly, improve the chances that epidemiologic studies can identify and accurately characterize health hazards. Am. J. Ind. Med. 45:113–122, 2004. © 2003 Wiley‐Liss, Inc.
Zur Entwicklung der Dip‐Pen‐Nanolithographie
Authors: Ginger David S. , Zhang Hua , Mirkin Chad A.
Published: December 2003

Die Möglichkeit zur gezielten Manipulation der chemischen Zusammensetzung und Struktur einer Oberfläche auf der Längenskala von 1 bis 100 nm ist von zentraler Bedeutung für einen breiten Bereich der nanotechnologischen Forschung, angefangen mit Studien zur elektronischen Leitfähigkeit, über die Katalyse hin zur biologischen Erkennung. Die Dip‐Pen‐Nanolithographie (DPN) ist eine neue Direktschreibmethode mit einem Kraftfeldmikroskop zur Erzeugung einer strukturierten chemischen Funktionalität auf einer Oberfläche im Sub‐100‐nm‐Bereich. In diesem Aufsatz stellen wir das Prinzip der DPN vor und betrachten die Entwicklungen der letzten Jahre. Die Themen erstrecken sich von der Entwicklung neuer DPN‐kompatibler Materialien über experimentelle und theoretische Untersuchungen der Prozesse, die den Spitze‐Substrat‐Transport der Tinte steuern, bis hin zur Implementierung von mikroelektromechanischen Systemen (MEMs) für DPN‐Parallelanwendungen.
A Planning Strategy for Diversity‐Oriented Synthesis
Authors: Burke Martin D. , Schreiber Stuart L.
Published: December 2003

In contrast to target‐oriented synthesis (TOS) and medicinal or combinatorial chemistry, which aim to access precise or dense regions of chemistry space, diversity‐oriented synthesis (DOS) populates chemical space broadly with small‐molecules having diverse structures. The goals of DOS include the development of pathways leading to the efficient (three‐ to five‐step) synthesis of collections of small molecules having skeletal and stereochemical diversity with defined coordinates in chemical space. Ideally, these pathways also yield compounds having the potential to attach appendages site‐ and stereoselectively to a variety of attachment sites during a post‐screening, maturation stage. The diverse skeletons and stereochemistries ensure that the appendages can be positioned in multiple orientations about the surface of the molecules. TOS as well as medicinal and combinatorial chemistries have been advanced by the development of retrosynthetic analysis. Although the distinct goals of DOS do not permit the application of retrosynthetic concepts and thinking, these foundations are being built on, by using parallel logic, to develop a complementary procedure known as forward‐synthetic analysis. This analysis facilitates synthetic planning, communication, and teaching in this evolving discipline.
Bioinspired Molecular Design of Light‐Harvesting Multiporphyrin Arrays
Authors: Choi Myung‐Seok , Yamazaki Tomoko , Yamazaki Iwao , Aida Takuzo
Published: December 2003

Recent progress in fundamental studies on multiporphyrin arrays has provided structural parameters for the molecular design of artificial light‐harvesting antennae which mimic the wheel‐like antenna complexes of photosynthetic purple bacteria. Covalent and noncovalent approaches have been employed for the construction of artificial light‐harvesting multiporphyrin arrays. Such arrays are categorized into ring‐shaped, windmill‐shaped, star‐shaped, and dendritic architectures. In particular, dendritic multiporphyrin arrays have been proven to be promising candidates for both providing a large absorption cross‐section and enabling the vectorial transfer of energy over a long distance to a designated point. Such molecular and supramolecular systems are also expected to be potent components for molecular electronics and photonic devices.
Cover Picture: The Evolution of Dip‐Pen Nanolithography (Angew. Chem. Int. Ed. 1/2004)
Authors: Ginger David S. , Zhang Hua , Mirkin Chad A.
Published: December 2003

Dip‐Pen Nanolithography makes possible rapid patterning of surfaces on the nanometer scale. The cover picture clearly shows the principles of this technique: the deposition of dye molecules from an atomic force microscopy tip onto a substrate. Feymans 1960 dictum on miniturization, shown in nanometer‐sized type in the background, is proving to be once again applicable. C. A. Mirkin et al. summarize in their Review on page 30 ff. the current status of dip‐pen lithography and predict possible future developments.
Relationship of adipokinetic hormone I and II to migratory propensity in the grasshopper, Melanoplus sanguinipes
Authors: Min Kyung Jin , Taub‐Montemayor Tina E. , Linse Klaus D. , Kent Jack W. , Rankin Mary Ann
Published: December 2003

This report examines three aspects of adipokinetic hormone (AKH) involvement in migratory flight behavior in the grasshopper, Melanoplus sanguinipes. The titer of hemolymph AKH I during long‐duration tethered flight was examined using radioimmunoassay (RIA) after narrow bore RP‐HPLC. The hemolymph fraction containing AKH I was assayed using commercially available anti‐Tyr1‐AKH I serum. Titer determinations of hemolymph AKH were done at rest and after various periods of flight. The amount of AKH I released from the corpora cardiaca during flight was estimated. When resting levels of AKH I and II in corpora cardiaca (CC) of migrants and non‐migrants were examined with HPLC, no significant differences in AKH levels were detected between non‐migrants, animals that had flown for 1 h to identify them as migrants, and animals that had flown to exhaustion (i.e., voluntary cessation). CC levels of both AKH I and II were less in this species than in locusts. When the lipid mobilization in response to AKH I and II was compared in migrants (animals that had self‐identified as migrants in a 1‐h tethered flight test) and non‐migrants (animals that would not perform a 1‐h flight in a tethered flight test), the adipokinetic response to AKH I was greater in migrants than in non‐migrants, possibly indicating differences in level of sensitivity or number of receptors in the target tissues. AKH II had little effect on hemolymph lipid levels in either flight group, and may not play a significant role in lipid mobilization in this species. Arch. Insect Biochem. Physiol. 55:33–42, 2004. © 2003 Wiley‐Liss, Inc.
Pathways and destination of some male gland secretions in female Locusta migratoria migratorioides (R&F) after insemination
Authors: Lay Martin , Loher Werner , Hartmann Rüdiger
Published: December 2003

The white secretions (WS) from the tubules of the male accessory glands (AG) of Locusta migratoria are composed of peptides and proteins. The WS are transferred during mating to the female's spermatheca. They have been followed to their destinations with immunological and radioactive marker techniques. In the spermatheca, peptides are split off from WS‐protein complexes, permeate the spermathecal epithelium via glandular cells, enter the hemolymph and attach to other proteins in various target organs such as the dorsal fat body, the preterminal/terminal oocytes, and the follicular cells. In developing eggs, they concentrate at the posterior pole where sperm enters the egg, and in early embryogenesis they are found in the germ band. These results extend the functions of the spermatheca and the role of the male during the reproductive process. Arch. Insect Biochem. Physiol. 55:1–25, 2004. © 2003 Wiley‐Liss, Inc.
Stimulation of midgut stem cell proliferation by Manduca sexta α‐arylphorin
Authors: Blackburn Michael B. , Loeb Marcia J. , Clark Edward , Jaffe Howard
Published: December 2003

Extracts of the green‐colored perivisceral fat body of newly ecdysed Manduca sexta pupae stimulate mitosis in midgut stem cells of Heliothis virescens cultured in vitro. Using a combination of cation‐ and anion‐exchange chromatography, we have isolated a protein from these fat body extracts that accounts for the observed stem cell proliferation. SDS‐PAGE analysis of the protein results in a single band of 77 kDa. Sequences of tryptic peptides from this protein are identical to internal sequences of the storage hexamer α‐arylphorin. The α‐arylphorin isolated by our procedure represents a small fraction of the total arylphorin present in the fat body extract. However, it alone seems responsible for the stimulation of mitotic activity in H. virescens midgut stem cells. Arch. Insect Biochem. Physiol. 55:26–32, 2004. Published 2003 Wiley‐Liss, Inc.
Immune stimulation in the silkworm, Bombyx mori L., by CpG oligodeoxynucleotides
Authors: Kim Iksoo , Kim Sang‐Hyun , Lee Young Shin , Yun Eun Kyung , Lee Heui‐Sam , Kim Jin‐Won , Ryu Kang‐Sun , Kang Pil‐Don , Lee In Hee
Published: December 2003

Synthetic ODNs containing unmethylated CpG dinucleotides are known to stimulate immune responses in vertebrates, but so far the effect has not been studied in insects. In this report, we describe an induction of immune response following injection of oligodeoxynucleotides (ODNs) into the insect hemocoel. The fifth instar silkworm (Bombyx mori L.) larvae were injected with several synthetic ODNs containing variable number of unmethylated CpG motifs, heat‐denatured genomic DNA of B. mori itself, or intact genomic DNA to observe a new induction pattern in the insect immune mechanism. When the induction of immune response was examined based on the expression rates of genes for antibacterial peptides such as attacin and cecropin, we could confirm that it was triggered upon injection of ODNs. The expression was, however, neither dependent on numbers of CpG motifs nor methylation of CpGs in ODNs. Furthermore, it was confirmed that the presence of CpG in ODN was not involved in the induction pattern of insect immunity caused by ODNs, although it has been reported that vertebrates respond in a specific manner against invading ODNs containing CpG dinucleotides. In addition, insect immunity was not stimulated by injection of intact DNA from host. In contrast, the injection of denatured genomic DNA provoked the host immune reaction. Taken together, our data suggest that foreignness of ODNs or DNA might be a key factor in the induction of insect immunity. Arch. Insect Biochem. Physiol. 55:43–48, 2004. © 2003 Wiley‐Liss, Inc.
Determination of ampicillin and amoxycillin by flow injection chemiluminescence method based on their enhancing effects on the luminol–periodate reaction
Authors: Li Yinhuan , Tang Yuhai , Yao Hong , Fu Junmei
Published: December 2003

In this work, a new flow injection chemiluminescence method is described for the determination of ampicillin and amoxycillin. The method is based on the strong enhancing effects of these antibiotics on the luminol–periodate reaction. The present method allows the measurements of ampicillin in the range 0.02–1.0 mg/L range and amoxycillin in the range 0.1–10.0 mg/L range with the relative standard deviations within 0.8–2.0%. The sampling frequency was calculated about 90/h. The method was successfully applied to the determination of ampicillin and amoxycillin in pharmaceutical preparations. A brief discussion on the possible chemiluminescence reaction mechanism is presented. Copyright © 2003 John Wiley & Sons, Ltd.
A competitive marathon race decreases neutrophil functions in athletes
Authors: Chinda Daisuke , Nakaji Shigeyuki , Umeda Takashi , Shimoyama Tadashi , Kurakake Shigeyoshi , Okamura Noriyoshi , Kumae Takashi , Sugawara Kazuo
Published: December 2003

A full marathon is the longest running race in official track events and is a form of acute exercise. However, no studies have examined the acute neutrophil function response to a competitive marathon race. Thirty‐six male athletes who had just completed the 42.195 km course of the 50th Beppu‐Oita Mainichi Marathon were enrolled in this study. Neutrophil oxidative burst activity, phagocytic activity and expression of CD11b and CD16 per cell were measured by flow cytometry immediately before and after the marathon. Total leukocyte/neutrophil counts increased significantly (p < 0.001), whereas total oxidative burst activity per neutrophil cell decreased significantly after the race (p < 0.001). Furthermore, total phagocytic activity per neutrophil cell also decreased after the race, although it was not significant (p = 0.08). Although CD11b expression per cell did not change, the expression of CD16 per cell significantly decreased (p < 0.001) after the race. In conclusion, a competitive marathon race decreased neutrophil functions (oxidative burst activity and phagocytic activity), which may be partly due to a decrease in CD16 expression. The increase in total neutrophil counts might reflect a compensatory response to counteract the decrease in neutrophil functions. Copyright © 2003 John Wiley & Sons, Ltd.
Ecabet sodium attenuates reactive oxygen species produced by neutrophils after priming with bacterial lipopolysaccharides
Authors: Munakata Wataru , Liu Qiang , Shimoyama Tadashi , Sawaya Manabu , Umeda Takashi , Sugawara Kazuo
Published: December 2003

The pathogenic roles of reactive oxygen species (ROS) have been implicated in ulcerative colitis (UC). The aim of this study was to examine the effects of ecabet sodium on ROS produced by human neutrophils, particularly after being primed by bacterial lipopolysaccharides (LPS). Neutrophils were isolated from six healthy volunteers. Each well of a 96‐well microplate received neutrophil suspension (1.0 × 105 cells) and the plates were incubated at 37°C for 30 min with or without E. coli LPS (f.c. 0.001 ng/µL). Ecabet sodium (f.c. 0–5.0 mg/mL) was added before starting or after finishing the incubation. Neutrophils were stimulated by opsonized zymosan (OZ; 1.0 mg/mL) or calcium ionophore (A21837; 0.3 µmol/L) and luminol‐dependent chemiluminescence response was measured using a Lumi Box H‐1000. Ecabet sodium attenuated ROS production at a concentration of 5.0 mg/mL (p < 0.05) in LPS‐primed neutrophils. However, attenuating effects were not significantly different when ecabet sodium was added before or after the incubation with E. coli LPS. Ecabet sodium may have some attenuating effects on ROS produced by human neutrophils even after neutrophils are primed by bacterial LPS. These results may explain, in part, the therapeutic effects of ecabet sodium for UC. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis, stability, and protonation studies of a self‐complementary dodecamer containing the modified nucleoside 2′‐deoxyzebularine
Authors: Vives M. , Eritja R. , Tauler R. , Marquez V. E. , Gargallo R.
Published: December 2003

The nucleoside 2′‐deoxyzebularine (K) was incorporated into the self‐complementary dodecamer 5′‐CGTACGKGTACG‐3′ by solid‐phase 2‐cyanoethylphosphoramidite chemistry using dimethoxytrityl (DMT) as the 5′‐hydroxyl protecting group. Standard synthesis cycles using trichloroacetic acid and short ammonia treatment (50°C for 30 min) were found to be the optimal conditions to obtain the desired dodecamer with minimum acid and basic degradation of the acid‐ and base‐sensitive 2‐pyrimidinone residue. The protonation equilibria of the K nucleoside and of the dodecamer at 37°C were studied by means of spectroscopically monitored titrations. For the K nucleoside, a pKa value of 3.13 ± 0.09 was obtained. For the dodecamer, four acid‐base species were found in the pH range 2–12, with pKa values of 9.60 ± 0.07, 4.46 ± 0.16, and 2.87 ± 0.19. Melting experiments were carried out to confirm the proposed acid‐base concentration profiles. Finally, kinetic experiments were also carried out at several pH values to evaluate the stability of the K nucleoside and of the dodecamer. An increased stability was shown by the K nucleoside when incorporated into the dodecamer. Multivariate methods based on both hard‐ and soft‐modeling were applied for the analysis of spectroscopic data, allowing the estimation of concentration profiles and pure spectra. © 2003 Wiley Periodicals, Inc. Biopolymers 70: 27–43, 2004
Understanding the transition states of phosphodiester bond cleavage: Insights from heavy atom isotope effects
Authors: Cassano Adam G. , Anderson Vernon E. , Harris Michael E.
Published: December 2003

The nucleotides of DNA and RNA are joined by phosphodiester linkages whose synthesis and hydrolysis are catalyzed by numerous essential enzymes. Two prominent mechanisms have been proposed for RNA and protein enzyme catalyzed cleavage of phosphodiester bonds in RNA: (a) intramolecular nucleophilic attack by the 2′‐hydroxyl group adjacent to the reactive phosphate; and (b) intermolecular nucleophilic attack by hydroxide, or other oxyanion. The general features of these two mechanisms have been established by physical organic chemical analyses; however, a more detailed understanding of the transition states of these reactions is emerging from recent kinetic isotope effect (KIE) studies. The recent data show interesting differences between the chemical mechanisms and transition state structures of the inter‐ and intramolecular reactions, as well as provide information on the impact of metal ion, acid, and base catalysis on these mechanisms. Importantly, recent nonenzymatic model studies show that interactions with divalent metal ions, an important feature of many phosphodiesterase active sites, can influence both the mechanism and transition state structure of nonenzymatic phosphodiester cleavage. Such detailed investigations are important because they mimic catalytic strategies employed by both RNA and protein phosphodiesterases, and so set the stage for explorations of enzyme‐catalyzed transition states. Application of KIE analyses for this class of enzymes is just beginning, and several important technical challenges remain to be overcome. Nonetheless, such studies hold great promise since they will provide novel insights into the role of metal ions and other active site interactions. © 2003 Wiley Periodicals, Inc. Biopolymers 73: 110–129, 2004
New approaches to targeting RNA with oligonucleotides: Inhibition of group I intron self‐splicing
Authors: Disney Matthew D. , Childs Jessica L. , Turner Douglas H.
Published: December 2003

RNA is one class of relatively unexplored drug targets. Since RNAs play a myriad of essential roles, it is likely that new drugs can be developed that target RNA. There are several factors that make targeting RNA particularly attractive. First, the amount of information about the roles of RNA in essential biological processes is currently being expanded. Second, sequence information about targetable RNA is pouring out of genome sequencing efforts at unprecedented levels. Third, designing and screening potential oligonucleotide therapeutics to target RNA is relatively simple. The use of oligonucleotides in cell culture, however, presents several challenges such as oligonucleotide uptake and stability, and selective targeting of genes of interest. Here, we review investigations aimed at targeting RNA with oligonucleotides that can circumvent several of these potential problems. The hallmark of the strategies discussed is the use of short oligonucleotides, which may have the advantage of higher cellular uptake and improved binding selectivity compared to longer oligonucleotides. These strategies have been applied to Group I introns from the mammalian pathogens Pneumocystis carinii and Candida albicans. Both are examples of fungal infections that are increasing in number and prevalence. © 2003 Wiley Periodicals, Inc. Biopolymers 73: 151–161, 2004
Roles of protein subunits in RNA–protein complexes: Lessons from ribonuclease P
Authors: Hsieh John , Andrews Andy J. , Fierke Carol A.
Published: December 2003

Ribonucleoproteins (RNP) are involved in many essential processes in life. However, the roles of RNA and protein subunits in an RNP complex are often hard to dissect. In many RNP complexes, including the ribosome and the Group II introns, one main function of the protein subunits is to facilitate RNA folding. However, in other systems, the protein subunits may perform additional functions, and can affect the biological activities of the RNP complexes. In this review, we use ribonuclease P (RNase P) as an example to illustrate how the protein subunit of this RNP affects different aspects of catalysis. RNase P plays an essential role in the processing of the precursor to transfer RNA (pre‐tRNA) and is found in all three domains of life. While every cell has an RNase P (ribonuclease P) enzyme, only the bacterial and some of the archaeal RNase P RNAs (RNA component of RNase P) are active in vitro in the absence of the RNase P protein. RNase P is a remarkable enzyme in the fact that it has a conserved catalytic core composed of RNA around which a diverse array of protein(s) interact to create the RNase P holoenzyme. This combination of highly conserved RNA and altered protein components is a puzzle that allows the dissection of the functional roles of protein subunits in these RNP complexes. © 2003 Wiley Periodicals, Inc. Biopolymers 73: 79–89, 2004
Hydration dependence of backbone and side chain polylysine dynamics: A 13C solid‐state NMR and IR spectroscopy study
Authors: Krushelnitsky Alexey , Faizullin Dzhigangir , Reichert Detlef
Published: December 2003

The molecular dynamics of solid poly‐L‐lysine has been studied by the following natural abundance 13C‐NMR relaxation methods: measurements of the relaxation times T1 at two resonance frequencies, off‐resonance T1ρ at two spin‐lock frequencies, and proton‐decoupled T1ρ. Experiments were performed at different temperatures and hydration levels (up to 17% H2O by weight). The natural abundance 13C‐CPMAS spectrum of polylysine provides spectral resolution of all types of backbone and side chain carbons and thus, dynamic parameters could be determined separately for each of them. At the same time, the conformational properties of polylysine were investigated by Fourier transform infrared spectroscopy. The data obtained from the different NMR experiments were simultaneously analyzed using the correlation function formalism and model‐free approach. The results indicate that in dry polylysine both backbone and side chains take part in two low amplitude motions with correlation times of the order of 10−4 s and 10−9 s. Upon hydration, the dynamic parameters of the backbone remain almost constant except for the amplitude of the slower process that increases moderately. The side chain dynamics reveals a much stronger hydration response: the amplitudes of both slow and fast motions increase significantly and the correlation time of the slow motion shortens by about five orders of magnitude, and at hydration levels of more than 10% H2O fast and slow side chain motions are experimentally indistinguishable. These changes in the molecular dynamics cannot be ascribed to any hydration‐dependent conformational transitions of polylysine because IR spectra reveal almost no hydration dependence in either backbone or side chain absorption domains. The physical nature of the fast and slow motions, their correlation time distributions, and hydration dependence of microdynamic parameters are discussed. © 2003 Wiley Periodicals, Inc. Biopolymers 73: 1–15, 2004
Synthesis of Tissues and Organs
Authors: Yannas Ioannis V.
Published: December 2003

Symbolism that describes the synthetic processes for chemical compounds has been used to describe, in qualitative terms, the synthesis of tissues and organs at the correct anatomical site. The synthetic process is summarized in the reaction diagram, a shorthand representation of the reactants, reactor, and products. Analysis of a large number of independent protocols has led to identification of the simplest synthetic pathways for two organs that have been studied extensively: skin and peripheral nerves. These apparently irreducible reaction diagrams for the two organs are not only simple but surprisingly similar, a fact suggesting the existence of general rules for the synthesis of other organs as well. The only two reactants that are required are an active scaffold (a macromolecular network synthesized as a highly porous analogue of the extracellular matrix) and a seeding of epithelial cells of the organ being synthesized. Scaffolds possessed biological (regenerative) activity provided that they were capable of blocking the contraction process that leads to closure of the injured site. Such activity requires that the density of ligands for binding of contractile cells on the scaffold maintains a sufficiently high level over the period of synthesis.
Recognition of Planar and Nonplanar Ligands in the Malachite Green–RNA Aptamer Complex
Authors: Flinders Jeremy , DeFina Steven C. , Brackett David M. , Baugh Chris , Wilson Charles , Dieckmann Thorsten
Published: December 2003

Ribonucleic acids are an attractive drug target owing to their central role in many pathological processes. Notwithstanding this potential, RNA has only rarely been successfully targeted with novel drugs. The difficulty of targeting RNA is at least in part due to the unusual mode of binding found in most small‐molecule–RNA complexes: the ligand binding pocket of the RNA is largely unstructured in the absence of ligand and forms a defined structure only with the ligand acting as scaffold for folding. Moreover, electrostatic interactions between RNA and ligand can also induce significant changes in the ligand structure due to the polyanionic nature of the RNA. Aptamers are ideal model systems to study these kinds of interactions owing to their small size and the ease with which they can be evolved to recognize a large variety of different ligands. Here we present the solution structure of an RNA aptamer that binds triphenyl dyes in complex with malachite green and compare it with a previously determined crystal structure of a complex formed with tetramethylrosamine. The structures illustrate how the same RNA binding pocket can adapt to accommodate both planar and nonplanar ligands. Binding studies with single‐ and double‐substitution mutant aptamers are used to correlate three‐dimensional structure with complex stability. The two RNA–ligand complex structures allow a discussion of structural changes that have been observed in the ligand in the context of the overall complex structure. Base pairing and stacking interactions within the RNA fold the phosphate backbone into a structure that results in an asymmetric charge distribution within the binding pocket that forces the ligand to adapt through a redistribution of the positive partial charge.
Fungal Aerobic Reductive Dechlorination of Ethyl 2‐Chloroacetoacetate by Saccharomyces cerevisiae: Mechanism of a Novel Type of Microbial Dehalogenation
Authors: Jörg Gerhard , Bertau Martin
Published: December 2003

Saccharomyces cerevisiae reduces the β‐keto ester ethyl 2‐chloroacetoacetate to the respective chiral cis‐ and trans‐β‐hydroxy esters. In the course of chiral reduction, competing dehalogenation of the xenobiotic substrate to ethyl acetoacetate occurs, in a reaction mediated by cytosolic glutathione (GSH). Mechanistically, the dechlorination is a novel type of glutathione‐dependent dehalogenation catalysed by an as yet unidentified glutathione‐dependent dehalogenase. The first step consists of a nucleophilic replacement of the chloride substituent by glutathione. In the subsequent enzyme‐catalysed step, a second glutathione molecule liberates the dehalogenation product by thiolytic attack at the thioether bridge, resulting in a net transfer of two electrons to the substrate and in the formation of glutathione disulfide (GSSG). Being effective under aerobic conditions and catalysed by a fungus, this reductive dechlorination of an aliphatic substrate is an outstanding example of a novel, glutathione‐mediated microbial dehalogenation.
Structure Investigation of TiIV‐BODOLates Involved in the Catalytic Asymmetric Reduction of Ketones Using Catecholborane
Authors: Sarvary Ian , Norrby Per‐Ola , Frejd Torbjörn
Published: December 2003

The complexes formed by the reaction of [Ti(OiPr)4] and bicyclo‐octanediols (BODOLs) 1 and 2 (1:1) are useful as chiral catalysts in asymmetric reductions and were investigated by 1H NMR spectroscopy and computational methods. A consistent picture emerged of head‐to‐tail dimers being kept together via a Ti‐O‐Ti‐O μ‐oxo bridge similar to the Ti‐tartrates but different from the corresponding Ti‐BINOLates and Ti‐TADDOLates.
Acid–Base Sensors Based on Novel Quinone‐Type Dyes
Authors: Elhabiri Mourad , Siri Olivier , Sornosa‐Tent Alejandra , Albrecht‐Gary Anne‐Marie , Braunstein Pierre
Published: December 2003

We present a detailed study on the acid–base behaviour of a family of “potentially antiaromatic” p‐benzoquinonediimine ligands. These 12π electron molecules can be considered as constituted of two chemically connected but electronically not conjugated 6π‐electron subunits. Upon successive protonation, “mono” and “double” cyanine‐type chromophores are generated in solution and allow a precise and sensitive spectrophotometric detection. These molecules represent a new class of tunable quinones whose electronic and structural properties can be triggered by proton input, as established by a complete physico‐chemical study involving a combination of potentiometric and spectrophotometric methods (absorption and emission).
Chiral Xyliphos Complexes for the Catalytic Imine Hydrogenation Leading to the Metolachlor Herbicide: Isolation of Catalyst–Substrate Adducts
Authors: Dorta Romano , Broggini Diego , Stoop Robert , Rüegger Heinz , Spindler Felix , Togni Antonio
Published: December 2003

Iridium complexes relevant to the catalytic enantioselective hydrogenation of 2‐methyl‐6‐ethylphenyl‐1′‐methyl‐2′‐methoxyethylimine (MEA‐imine, 1) in the Syngenta Metolachlor (3) process were prepared and characterized. Reaction of the diphosphane (S)‐1‐[(R)‐2‐(diphenylphosphanyl)ferrocenyl]ethyldi(3,5‐xylyl)phosphane ((S)‐(R)‐Xyliphos, (S)‐(R)‐4) with [Ir2(μ‐Cl)2(cod)2] (cod=1,5‐cyclooctadiene) afforded [Ir(Cl)(cod){(S)‐(R)‐4}] (7), which reacted with AgBF4 to form [Ir(cod){(S)‐(R)‐4}]BF4 (8). Complexes 7 and 8 reacted with iodide to yield [Ir(I)(cod){(S)‐(R)‐4}] (9). When 9 was treated with one and two equivalents of HBF4, two isomers of the cationic IrIII iodo hydrido complex [Ir(I)(H)(cod){(S)‐(R)‐4}]BF4 were isolated (10 and 11, respectively). Complex 9 was oxidized with one equivalent of I2 to give the iodo‐bridged dinuclear species [Ir2I2(μ‐I)3{(S)‐(R)‐4}2)]I (12). [Ir2(μ‐Cl)2(coe)4] (coe=cyclooctene) reacted with (S)‐(R)‐4 to yield the chloro‐bridged dinuclear complex [Ir2(μ‐Cl)2{(S)‐(R)‐4}2] (13). Complexes 7–12 were structurally characterized by single‐crystal X‐ray diffraction and tested as single‐component catalyst precursors for enantioselective hydrogenation of MEA‐imine. Complex 10 and dinuclear complex 12 gave the best catalytic results. Efforts were also directed at isolating substrate– or product–catalyst adducts: Treatment of 8 with 2,6‐dimethylphenyl‐1′‐methyl‐2′‐methoxyethylimine (DMA‐imine, 14, a model for 1) under H2 allowed four isomers of [Ir(H)2{(S)‐(R)‐4}(14)]BF4 (18–21) to be isolated. These analytically pure isomers were fully characterized by 2D NMR techniques. X‐ray structural analysis of an IrI–imine adduct, namely, [Ir(C2H4)2(14)]BF4 (25), which was prepared by reacting [IrCl(C2H4)4] with [Ag(14)2]BF4 (16), confirmed the κ2 coordination mode of imine 14.
A Unique Binaphthyl Strapped Iron–Porphyrin Catalyst for the Enantioselective Epoxidation of Terminal Olefins
Authors: Rose Eric , Ren Qi‐Zhi , Andrioletti Bruno
Published: December 2003

A new chiral binaphthyl‐strapped iron–porphyrin 4 b that exhibits unprecedented catalytic activity toward the enantioselective epoxidation of terminal olefins was synthesized. Typical enantiomeric excesses (ee) of 90 % were measured with a maximum of 97 % for the epoxidation of styrene, whereas the turnover numbers (TON) averaged 16 000.
Polyoxotungstate Photoinduced Alkylation of Electrophilic Alkenes by Cycloalkanes
Authors: Dondi Daniele , Fagnoni Maurizio , Molinari Alessandra , Maldotti Andrea , Albini Angelo
Published: December 2003

Alkyl radical obtained by irradiation of tetrabutylammonium decatungstate in acetonitrile in the presence of cycloalkanes (C5H10, C6H12, C7H14) are efficiently trapped by electrophilic alkenes (acrylonitrile, isopropylydenmalonitrile, isopropylydencyanoacetate) to give the corresponding alkylated aliphatic nitriles. The reaction can be carried out up to complete conversion of the alkene with reasonable (in most cases 60–65 %) yields. Addition of the radicals to the alkene is followed by electron transfer from reduced decatungstate regenerating the sensitizer (turn over number up to 60). Steady‐state measurements, EPR evidence, deuteration experiments and attempted intramolecular trapping of the adduct radical support the mechanistic proposal.
Ruthenium‐Catalyzed One‐Pot Double Allylation/Cycloisomerization of 1,3‐Dicarbonyl Compounds Leading to exo‐Methylenecyclopentanes
Authors: Yamamoto Yoshihiko , Nakagai Yu‐ichiro , Itoh Kenji
Published: December 2003

The ruthenium‐catalyzed one‐pot double allylation/cycloisomerization of 1,3‐diketones and methyl acetoacetate gave exo‐methylenecyclopentanes in moderate to good yields with high isomer selectivity. The double allylation step effectively proceeded in the presence of a RuII precatalyst, [Cp*RuCl(cod)], in 1,2‐dichloroethane at 90 °C. The subsequent cycloisomerization was carried out upon addition of triethylsilane as a hydride source without purification of a 1,6‐diene intermediate. Detailed inspections of the reaction by 1H NMR spectroscopy disclosed that triethylsilyl methyl ether plays an important role for the conversion of a ruthenium(IV) allyl complex formed in the double allylation step into a ruthenium(II) species required for the cycloisomerization.