bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of 6‐Amino Acid Substituted Derivatives of the Highly Potent Analgesic 14‐O‐Methyloxymorphone
Authors: Schütz Johannes , Brandt Wolfgang , Spetea Mariana , Wurst Klaus , Wunder Gerhard , Schmidhammer Helmut 
Published: July 2003

AbstractThe novel morphinans 13–18, which carry amino acid substituents at C(6), with potentially limited access to the central nervous system were prepared in two steps from 14‐O‐methyloxymorphone (5). Reductive amination with amino acid tert‐butyl esters gave compounds 7–12, which were hydrolyzed with tetrafluoroboric acid. Structure elucidation (including X‐ray analysis), preliminary μ‐opioid receptor binding studies, and calculations of pharmacokinetic parameters were carried out.
Polyprenylated Phloroglucinol Derivatives from Hypericum sampsonii
Authors: Lin Yun‐Lian , Wu Yu‐San 
Published: July 2003

AbstractSix new prenylated phloroglucinol derivatives, hypersampsones A–F (1–6), were isolated from the aerial part of Hypericum sampsonii, together with 2,4,6‐trihydroxybenzophenone, 2,4,6‐trihydroxybenzophenone 4‐O‐geranyl ether, 2,4,6‐trihydroxybenzophenone 3‐C‐geranyl ether, sampsoniones D and H. Their structures were elucidated by spectroscopic methods, mainly 1D‐ and 2D‐NMR spectroscopy and mass spectrometry.
Atropisomeric PˆN Ligands for the Palladium‐Catalyzed Copolymerization of Styrene with Carbon Monoxide. Preliminary Communication
Authors: Gsponer Achim , Consiglio Giambattista 
Published: July 2003

AbstractAchiral and chiral cationic palladium catalysts, modified with atropisomeric PˆN ligands with different steric and electronic properties, can efficiently produce poly(styrene‐alt‐CO) with essentially complete regioregularity and variable tacticity, depending on the ligand geometry; the electronic effect on catalytic activity depends on the geometry of the ligand.
Synthesis, Separation, and Theoretical Studies of Chiral Biphenyl Lignans (α‐ and β‐DDB)
Authors: Chang Junbiao , Chen Rongfeng , Guo Ruiyun , Dong Chunhong , Zhao Kang 
Published: July 2003

AbstractTwo biphenyl lignans, α‐ and β‐DDB (1 and 2, respectively) were efficiently synthesized without contamination by other regio‐isomers. The different yields of the Ullmann coupling reactions for the synthesis of 1 and 2 were rationalized by calculating steric hindrance, stability, entropy change, and heat‐of‐formation values. The enantiomers of 1 and 2 were readily separated by HPLC on a chiral stationary phase. Their configurations were assigned based on the Cotton effect of the authentic natural products.
Abundance and Vertical Distribution of the Phytobenthic Community within a Pool and Riffle Sequence of an Alpine Gravel Stream
Authors: Müllner Alexandra N. , Schagerl Michael 
Published: July 2003

AbstractIn the 2nd order mountain brook “Oberer Seebach” (Austria), diatoms and cyanoprokaryotes dominate the microphytobenthos, with the diatoms forming the richest species group.Comparative investigations of different habitats clearly show seasonal variations in algal species composition and biomass throughout the year. Pool habitats hold a higher number of taxa than riffle sites. In addition, phytobiomass is two‐ to nearly fourfold higher in pools. Based on investigations of the chlorophyll‐a vertical profiles within the coarse gravel sediments, the light discontinuity layer was determined to be situated at 7–10 cm sediment depth. Vertical distribution showed a maximum of taxa a few centimeters below the sediment surface. The same diatom taxa were found throughout all sampling dates, sediment depths and sampling sites.The results of exposed perforated metal tubes clearly indicate that the occurrence of phytobenthos in aphotic zones is primarily controlled by saltatory movements of the upper sediment layers driven by discharge.
Benthic Invertebrates and Metabolism of West Carpathian (Slovakia) Rivers
Authors: Šporka Ferdinand , Krno Il'ja 
Published: July 2003

AbstractWe examined benthic invertebrates and metabolism on the basis of the annual sampling of 9 types of running waters in the West Carpathians. Headwaters in general represent typical heterotrophic systems, except where they are high mountain streams, which are autotrophic. Lower down, the upper reaches of brooks are transition zones between heterotrophic and autotrophic systems. After the transition to an autotrophic system (which depends mainly on the primary producers) there is a considerable decrease in secondary production. Production is higher in the rivers of the Carpathian basin, as well as lower down the valley (submontane rivers and lower tributaries of submontane streams) where, within the autotrophic systems, there is a shift of metabolism from the bottom to the water column. The temperature days, altitude and slope of the stream and concentration of calcium influence production of macrozoobenthos.
The Choice of Standardisation Reveals a Significant Influence on the Dynamics of Bacterial Abundance in Newly Deposited River Sediments
Authors: Farnleitner Andreas H. , Kasimir Georg D. , Kavka Gerhard G. , Zechmeister Thomas C. , Mach Robert L. , Kirschner Alexander K. T. 
Published: July 2003

AbstractAfter a high water event of the River Danube in April 1994, bacterial cell numbers were determined in newly formed deposits in a backwater near Hainburg (Lower Austria) within a time course of 140 days. This data set shows that expressing bacterial numbers per fresh sediment volume, per sediment dry mass, or per pore‐water fluid volume, respectively, yield significantly different results and ecological conlusions. These findings refer particularly to intra‐study and time‐course comparisons as presented in our case. Bacterial cell numbers expressed per gram sediment dry mass revealed statistically significant differences between the beginning and the end of the study, whereas expressed per cm3 of fresh sediment or fluid volume of sediment pore water, no statistical difference could be detected. It is argued that these differences were caused by physical sediment compaction and mineralisation processes over the considered time‐course. Such mechanisms may simulate biological activity if some basic sediment parameters are neglected and thus standardisation has to be done with caution for the particular situation being observed.
Vertical Distribution of Benthic Macroinvertebrates in Riffles versus Deep Runs with Differing Contents of Fine Sediments (Weidlingbach, Austria)
Authors: Weigelhofer Gabriele , Waringer Johann 
Published: July 2003

AbstractDue to the erosiveness of their sediments, sandstone streams transport high loads of fine particles. The catchment of the Weidlingbach, a 12 km long tributary of the Danube northwest of Vienna, is dominated by calcareous sandstone, marl and slate. Mean sediment grain size ranges from 29.3 to 31.0 mm, and mean pore volume is approximately 20%. The third order study site is divided into a wide, shallow riffle section with high accumulations of fine sediments in the hyporheic zone and a narrow, deep run section with a lower percentage of fine sediments. Invertebrates were sampled to a sediment depth of 60 cm every second month using the freeze‐coring‐technique with electropositioning.Hyporheic invertebrate densities were significantly higher in sediments of the run than in those of the riffle section. Generally, hyporheic abundances decreased with increasing depth; however, the decline was more distinct within the riffle than the run section. Furthermore, we observed a strong negative correlation between the percentage of fine sediments (<2 mm) and hyporheic invertebrate densities.
The Development of a System to Assess the Ecological Quality of Streams Based on Macroinvertebrates – Design of the Sampling Programme within the AQEM Project
Authors: Hering Daniel , Buffagni Andrea , Moog Otto , Sandin Leonard , Sommerhäuser Mario , Stubauer Ilse , Feld Christian , Johnson Richard , Pinto Paulo , Skoulikidis Nikos , Verdonschot Piet , Zahrádková Svetlana 
Published: July 2003

AbstractThe EU Water Framework Directive (WFD) requires river assessment systems based on benthic invertebrates. The AQEM project is developing, at a European scale, such a methodology, based on a comparison of communities of reference streams and degraded streams. The project is focussing on three main impact types: morphological degradation, organic pollution and acidification.This paper presents the outline of the AQEM project with special emphasis on:– an overview of assessment systems with benthic invertebrates presently applied in Europe– an overview of stream typology approaches in Europe– the selection process of the stream types investigated in AQEM– the criteria used to select reference sites– the design of the sampling programme– the microhabitat‐based sampling method applied in AQEM– the links and possibilities of integration between AQEM and existing assessment systems.
Organic Matter Dynamics and Invertebrate Functional Groups in a Mountain Stream in the West Tatra Mountains, Poland
Authors: Galas Joanna , Dumnicka Elżbieta 
Published: July 2003

AbstractInvestigations were carried out at two sites on a low order mountain stream in order to characterise the role of macroinvertebrates in organic matter decomposition. Total benthic organic matter content ranged from 6 to 1304 g AFDM m−2. The fine fraction constituted more than 50% of the total POM at both sites in all seasons, except for autumn. In transported POM the coarse fraction dominated and its highest values were noted in May, after the snow melt season. The density of bottom fauna was five times higher on the sandy‐gravel bottom than on the stony bottom. In both habitats, gathering collectors and scrapers were most abundant; shredders constituted only a few percent of the benthic community in the stony habitat. Our results indicate that the role of shredders is small, and mechanical fragmentation and microbial activity are mainly responsible for fine particle formation.
Spatial Autocorrelation and Fractal Dimension of Alga Species Assemblage in a Gravel Stream of Central Europe
Authors: Komárek Ondrřej 
Published: July 2003

AbstractThe relationship of benthic diatom species to sampling scale was studied in two Moravian rivers that differ in substrate and discharge. Number of cells per mm2 of each species was used for statistical analysis. The distribution of abundance of benthic algae follows a fractal pattern, because it exhibits the same detail over a continuum of scales. DCA first axis score, variogram and fractal dimension were used for spatial autocorrelation estimation. The fractal dimensions obtained are generally close to 2, implying weak spatial dependence. The fractal dimension was not a constant function of scale, implying that patterns of spatial variation at one scale cannot be extrapolated to other scales. The results suggest that appropriate distances among samples of benthic algae must be considered.
Clogging Processes in Hyporheic Interstices of an Impounded River, the Danube at Vienna, Austria
Authors: Blaschke Alfred Paul , Steiner Karl‐Heinz , Schmalfuss Roland , Gutknecht Dieter , Sengschmitt Dieter 
Published: July 2003

AbstractStream‐aquifer interactions are influenced significantly by riverbed clogging processes. Detailed field observations have been made in the “Freudenau reservoir” of the Danube at Vienna. Different types of clogged layers have been observed. Multi‐level‐piezometers below the riverbed indicate that the overall clogging process consists of several clogging cycles of a few weeks each initiated by floods until a stable state is reached. Minor flood events cause a temporary increase in the leakage coefficient followed by a new decrease approaching the original level after a few weeks. Major flood events tended to add a sediment layer which re‐initiated the clogging process leading over to a lower level of the leakage coefficient. The computation of the water balance of the two reservoirs of the New Danube indicated a reduction of the seepage rate by about 40% to 60% over a period of 4.5 years. Undisturbed riverbed sediment samples taken by an innovative freeze‐panel‐sampling method demonstrate that the depth of the clogged layer is about 2 cm for two of the clogging types (external clogging and armour layer clogging). Video techniques were used to identify the different types of clogged layers and their variability in time and space. Additionally, this technique facilitated observations of macrozoobenthos organism activities in the hyporheic interstices.
Retention of Coarse Particulate Organic Matter on the Sediments of Njoro River, Kenya
Authors: Magana Adiel Micheni , Bretschko Gernot 
Published: July 2003

AbstractRetention of benthic organic matter (BOM) on the sediment surface of the Njoro River, Kenya was investigated between February 1998 and June 1999 at two sites, differing in channel morphology and riparian vegetation density and composition i.e. open‐canopy and closed‐canopy sites. Monthly accumulation of benthic organic matter (BOM) was highly variable, ranging from 97.3 to 6691.8 and from 206.6 to 1936.3 g ash free dry weight m−2 (AFDW) with a mean ± CL of 1133.3 ± 794.5 and 834.9 ± 275.8 g AFDW m−2 at the closed and open canopy sites, respectively. Pools retained higher amounts of particulate organic matter than riffles. Surprisingly, differences in retention of BOM at the two sites were not significant. Temporal distribution of benthic organic matter showed no distinct relationship with throughfall and bank runoff input patterns of particulate organic matter. Wood debris comprised 47% and 36% while leaves comprised 34% and 31% of the total BOM at the closed and open canopy sites, respectively; the rest was fruits and fine benthic organic matter (FBOM > 0.1 mm but < 1 mm). Out of 19 plant species recorded at both sites, only 8 species reflected their contribution in BOM with Syzygium cordatum contributing over 80% of the identifiable leaf litter. It is presumed that the variations in spatial and temporal distribution of BOM at the two sites is due to differences in discharge regimes, retention structures and riparian vegetation characteristics.
Biocompatibility and other properties of acrylic bone cements prepared with antiseptic activators
Authors: de la Torre B. , Fernández M. , Vázquez B. , Collía F. , de Pedro J. A. , López‐Bravo A. , San Román J. 
Published: July 2003

AbstractAcrylic bone cements prepared with activators of reduced toxicity have been formulated with the aim of improving the biocompatibility of the final material. The activators used were N,N‐dimethylaminobenzyl alcohol (DMOH) and 4,4′‐dimethylamino benzydrol (BZN). The toxicity, cytotoxicity, and antiseptic action of these activators were first studied. DMOH and BZN presented LD50 values 3–4 times higher than DMT, were less cytotoxic against polymorphonuclear leucocytes, and possessed an antimicrobial character, with a high activity against the most representative microorganisms involved in postoperative infections. The properties of the acrylic bone cements formulated with DMOH and BZN were evaluated to determine the influence of these activators on the curing process and the physicochemical characteristics of the cements. A decrease of the peak temperature was observed for the curing with DMOH or BZN with respect to that of one commercially available formulation (CMW 3). However, residual monomer content and mechanical properties in tension and compression were comparable to those of CMW 3. The biocompatibility of acrylic bone cements containing DMOH or BZN was studied and compared with CMW 3. To that end, intramuscular and intraosseous implantation procedures were carried out and the results were obtained from the histological analysis of the surrounding tissues at different periods of time. Implantation of rods of cement into the dorsal muscle of rats showed the presence of a membrane of connective tissue, which increased in collagen fibers with time of implantation, for all formulations. The intraosseous implantation of the cements in the dough state in the femur of rabbits, revealed a higher and early osseous neoformation, with the presence of osteoid material surrounding the rest of the cured material, for the cement prepared with the activator BZN in comparison with that obtained following the implantation of the cement cured with DMOH or DMT (CMW 3). © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 66B: 502–513, 2003
Long‐term wear of ceramic matrix composite materials for hip prostheses under severe swing phase microseparation
Authors: Stewart Todd D. , Tipper Joanne L. , Insley Gerard , Streicher Robert M. , Ingham Eileen , Fisher John 
Published: July 2003

AbstractThe purpose of this study was to evaluate the long‐term wear performance of alumina matrix composite (AMC) heads against alumina matrix composite inserts and alumina matrix composite heads against alumina (Al) inserts with the use of a hip‐joint simulator incorporating severe swing phase joint microseparation. The wear of AMC on Al produced an average wear rate of 0.61 mm3/million cycles over the 5‐million‐cycle test duration. The wear of AMC on AMC produced an average wear rate of 0.16 mm3/million cycles over the 5‐million‐cycle test duration. Both the AMC on alumina and AMC on AMC produced significantly lower wear than previously tested HIPed alumina, where an average wear rate of 1.84 mm3/million cycles was reported over 5 million cycles. The wear mechanisms and wear debris of AMC on AMC and AMC on Al were similar to those observed in previous alumina retrieval studies with stripe wear caused by intragranular fracture and wear debris consisting of predominantly uniform 10–20‐nm‐sized particles and a few irregular particles up to 3 μm in size. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 66B: 567–573, 2003
Autologous bone versus calcium‐phosphate ceramics in treatment of experimental bone defects
Authors: Bloemers Frank W. , Blokhuis Taco J. , Patka Peter , Bakker Fred C. , Wippermann Burkhard W. , Haarman Henk J.Th.M. 
Published: July 2003

AbstractAutologous bone grafting is currently considered the treatment of choice for correction of large bone defects. However, to avoid morbidity associated with autologous bone harvesting many artificial bone‐substitute materials have been developed over the years. A new generation of resorbable materials is emerging, with promising results so far. In order to investigate the possibility to use one of these new materials as an alternative with better results than hydroxyapatite, an experimental study was performed. A new resorbable calcium phosphate particles and paste forms, the latter of which hardens in situ after application. In 28 sheep, a 3‐cm segmental tibial defect was made and intramedullary fixed by an interlocking nail. Twelve weeks after defect filling, radiological, biomechanical, and histological examinations were performed. Mean radiographic and biomechanical tests results were compared with the Mann‐Whitney test. Significance was set at p < 0.05. Radiographically, the resorbable paste group performed better than all other groups. Biomechanical investigations showed a higher torsional stiffness (p = 0.049) for the resorbable calcium‐phosphate paste group in comparison with autologous bone. On histological examination, no adverse effects were observed in the calcium‐phosphate groups. Resorbtion by osteoclasts was seen in the resorbable implants. In conclusion, the current study shows an advantageous radiological and mechanical outcome for resorbable calcium phosphates. This indicates that these new materials might be a potential alternative for autologous bone grafting in humans. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 66B: 526–531, 2003
Enzymatic synthesis of l‐tryptophan and 5prime‐hydroxy‐l‐tryptophan labeled with deuterium and tritium at the alpha‐carbon position
Authors: Boroda E. , Rakowska S. , Kański R. , Kańska M. 
Published: July 2003

AbstractThe enzymatic synthesis of l‐tryptophan and its derivative 5′‐hydroxy‐l‐tryptophan labeled with deuterium and tritium at the α‐carbon position is reported. The mixture containing S‐methyl‐l‐cysteine, indole or 5‐hydroxyindole dissolved in deuteriated or tritiated water has been converted to [2‐2H]‐l‐tryptophan, [2‐3H]‐l‐tryptophan, 5′‐hydroxy‐[2‐2H]‐l‐tryptophan, and 5′‐hydroxy‐[2‐3H]‐l‐tryptophan, respectively, in a one‐pot reaction using the enzyme tryptophanase. The same reaction carried out in heavy water with THO added yielded either doubly labeled [2‐2H/3H]‐l‐tryptophan or 5′‐hydroxy‐[2‐2H/3H]‐l‐tryptophan. Copyright © 2003 John Wiley & Sons, Ltd.
A general method for the fluorine‐18 labelling of fluoroquinolone antibiotics
Authors: Langer Oliver , Mitterhauser Markus , Wadsak Wolfgang , Brunner Martin , Müller Ulrich , Kletter Kurt , Müller Markus 
Published: July 2003

AbstractFluoroquinolones are an important class of antibiotic agents with a broad spectrum of antibacterial activity. Labelling of fluoroquinolones with fluorine‐18 is of interest for the performance of pharmacokinetic measurements and the visualization of bacterial infections in humans with positron emission tomography. A two‐step radiosynthetic pathway to prepare fluorine‐18‐labelled ciprofloxacin (1‐cyclopropyl‐6‐[18F]fluoro‐1,4‐dihydro‐4‐oxo‐7‐(1‐piperazinyl)‐quinoline‐3‐carboxylic acid) has previously been developed. In the present work this approach was applied to the preparation of the structurally related compounds [18F]norfloxacin (1‐ethyl‐6‐[18F]fluoro‐1,4‐dihydro‐4‐oxo‐7‐(1‐piperazinyl)‐quinoline‐3‐carboxylic acid) and [18F]pefloxacin (1‐ethyl‐6‐[18F]fluoro‐1,4‐dihydro‐7‐(4‐methyl‐1‐piperazinyl)‐4‐oxo‐quinoline‐3‐carboxylic acid). The first step of the radiosynthesis consisted of a 18F for 19F exchange reaction on a 7‐chloro‐substituted precursor molecule, followed by coupling reactions with the amines piperazine or 1‐methylpiperazine. Starting from 51–58 GBq of [18F]fluoride 1.9–2.0 GBq of [18F]norfloxacin or [18F]pefloxacin, ready for intravenous injection, could be obtained in a synthesis time of 130 min (3.5–3.8% overall radiochemical yield). Moreover, the preparation of [18F]levofloxacin ((‐)‐(S)‐9‐[18F]fluoro‐2,3‐dihydro‐3‐methyl‐10‐(4‐methyl‐1‐piperazinyl)‐7‐oxo‐7H‐pyrido[1,2,3‐de]‐1,4‐benzoxazine‐6‐carboxylicacid) was attempted but failed to afford the desired product in practical amounts. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis of 1‐[4‐(m‐tolyl)amino‐6‐quinazolinyl]‐3‐[14C]‐methyl triazene: a radiolabeled probe for the combi‐targeting concept
Authors: Matheson Stephanie L. , Mzengeza Shadreck , Jean‐Claude Bertrand J. 
Published: July 2003

AbstractThe synthesis of 1‐[4‐(m‐tolyl)amino‐6‐quinazolinyl]‐3‐[14C]‐methyl triazene (SMA41) is described. This triazene was designed to be hydrolyzed under physiological conditions to N4‐m‐tolyl‐quinazoline‐4,6‐diamine (SMA52), a moderate inhibitor of the epidermal growth factor receptor (EGFR) and the DNA alkylating species [14C]‐methyldiazonium. A radiolabeled probe was needed to test the hypothesis that in situ hydrolysis of SMA41 may induce alkylation of the ATP binding site of EGFR. 14C‐SMA41 was obtained with a radiochemical yield of 21% and a specific activity of 54.6 mCi/mmol, as determined by HPLC quantitation and scintillation counting. Radio‐TLC analyses showed 98% radiochemical purity. Copyright © 2003 John Wiley & Sons, Ltd.
A novel probe for imaging amyloid‐β: Synthesis of F‐18 labelled BF‐108, an Acridine Orange analog
Authors: Shimadzu Hiroshi , Suemoto Takahiro , Suzuki Masako , Shiomitsu Tsuyoshi , Okamura Nobuyuki , Kudo Yukitsuka , Sawada Tohru 
Published: July 2003

AbstractThe synthesis of 3‐(2‐[18F]fluoroethyl)ethylamino‐6‐diethylaminoacridine ([18F]BF‐108), a potential positron‐labelled probe for imaging amyloid‐β is described. The precursor tosylate derivative was fluorinated with [18F]KF/ Kryptofix 222 in acetonitrile, and the crude product was purified by semi‐preparative HPLC to give the radiolabelled BF‐108. The radiochemical purity was >95% and the maximum specific activity was 33.9 TBq/mmol at the end of the synthesis (EOS). The synthesis time was 130 min from the end of bombardment (EOB). Copyright © 2003 John Wiley & Sons, Ltd.