bluuebunny/crossref_metadata_2025 huggingface dataset:
A Simple Compatibility Testing Protocol for Bentonite-Based Barrier Systems
Authors: Osicki RS , Fleming IR , Haug MD
Published: May 2004

This paper investigates macroscopically observable properties of bentonite. Bentonite slurries were prepared with varying pore water chemistry, using salt solutions for which compatibility problems have been shown. Using these samples, a rapid testing protocol was developed for evaluation of compatibility. Fann viscometer and filter press testing are well-established methods to examine bentonite quality and expected permeability of bentonite based barrier systems. This paper presents new research into the use of these simple tools to examine potential alteration or compatibility problems. Bentonite slurries made using the permeant of interest can be quickly evaluated for comparison with water-hydrated slurries. These results were confirmed with permeameter tests using GCLs. The permeability from the GCLs can be compared with the relative values inferred from the filter press and viscometer testing related to the double layer thickness. The authors believe that this work suggests that a few quick and simple tests can be done to evaluate potential compatibility issues with bentonite in natural form or in prefabricated geosynthetics. For industry, this will have the advantage of a very quick and cheap test that may be carried out to evaluate compatibility issues.
Porosity of Asphalt Concrete Made With Waste Shredded-Tire Rubber-Modified Binders
Authors: CÇelik ON
Published: May 2004

Most bituminous paving researchers agree that high air void content (high permeability) should be avoided in the design and construction of bituminous pavements. Void content in bituminous mixtures is one of the main approaches in determining the optimum binder content. The current design procedures and the Leeds design method provide an approach to determination of the air voids in bituminous mixtures. Because the determination of porosity in bituminous mixtures is based on a calculated value, which is dependent on the accuracy of the mix composition, it is difficult to use porosity as a crucial parameter for acceptance of constructed bituminous pavements. In fact, porosity measurements are often the source of dispute and disagreement between contractor and engineer. For this reason, it is important to develop methods for the direct measurement of porosity in the laboratory so that verification in the field can be made independent of the compaction of the mix. This paper introduces a new porosity measuring procedure based on the Leeds vacuum porosity meter and presents the results obtained from this apparatus for asphalt concrete made with shredded-rubber modified binder.
Evaluation of Hot Mix Asphalt Macro- and Microtexture
Authors: Stroup-Gardiner M , Studdard J , Wagner C
Published: May 2004

Pavement macrotexture is considered the primary factor in skid resistance at speeds over 65 km/h (40 mph). A total of 18 projects (9 Superpave and 9 Marshall mix designs) were evaluated to determine if the macrotexture of the pavement surface was influenced by gradation changes associated with the move to Superpave mix designs. The Federal Highway Administration ROSAN high-frequency laser system was used to measure macrotexture. Changes in microtexture, also a factor in skid resistance, were evaluated using a British Pendulum (BP) tester to determine the BP numbers of laboratory-compacted samples. Results indicated that the macrotexture did not change as a result of changes in mix design practices. The nominal maximum size of aggregate seemed to be the key factor in change in pavement surface macrotexture. Mixes, either Superpave or Marshall, with a nominal maximum size 9.5 mm or 12.5 mm have macrotextures of less than 0.5 mm. Based on information in the literature, the skid resistance for these Alabama pavements was estimated at 40 or higher.
Three-Dimensional Crack Detection Method for Structures Using Simulated Strain Gages and the Body Force Method
Authors: Yoshimura T , Harada T , Noguchi H , Yoshimura T
Published: May 2004

A method for estimating the stress field of an observed domain by considering the surface of a 3-dimensional object as a pseudo3-dimensional object has been proposed in a previous report by the present authors. In this method, some strain gages and the body force method are used. In this paper, the method is applied to crack detection in notched structures. A characteristic stress field attributable to the crack can be expected in the observed domain. Crack detection is then tried by showing the characteristic stress field. Detection of an ideal crack, which is a through crack or a quarter-circular crack on the hidden side, is studied using the finite-element method (FEM). Moreover, the stress fields are estimated using the present method from the FEM's stress values instead of actual stress values. In both a through crack and a quarter-circular hidden crack, the characteristic stress field can be shown; the characteristic stress field means that two stress concentrations exist along the notch. Finally, the application limits of the present method are shown.
Time-Constrained Scheduling and Module Allocation for On-Line Testability in Pipelined Data Paths
Authors: Ismaeel A , Mathew R
Published: May 2004

This paper presents an on-line testable-pipelined data path synthesis with the goal of minimizing testing time. An independent time-constrained scheduling with a module allocation algorithm for a pipelined data path is proposed. The algorithm takes any behavioral description represented as a data flow graph as input and generates a pipelined data path. The pipelined data path is composed of resources such as modules, registers, and multiplexers. Our on-line testing methodology applies to modules where multi type operations are assigned. The test is performed on each type of operation assigned to a module. The testing time is reduced by minimizing the overall number of types of operations assigned to modules. Thus, the objective is to minimize the overall number of types of operations assigned to all modules by performing pipelined data path synthesis. Experimental results confirm there can be some improvement in minimizing the overall number of types of operations assigned to all modules.
An Application of the Random Balance Method in Conjunction with the Plackett-Burman Screening Design in Metal Cutting Tests
Authors: Astakhov VP
Published: May 2004

This papers deals with an experimental study of metal cutting, particularly gundrilling. It argues that a proper experimental methodology based on the design of experiments (DOE) is an appropriate instrument to improve productivity and efficiency of machining. A screening DOE based on the random balance method and the Plackett-Burman screening design is considered. Such a DOE is referred to as a sieve design. The proposed method has proven to be very useful at the first stage of an experimental study of complex parameters as, for example, tool life testing, where the experimentalist wishes to include into consideration many design and process parameters. Conducting a relatively simple sieve DOE, the experimentalist easily can distinguish significant factors and their interactions of any order to be used in the subsequent full block DOE. A practical example of an application using the proposed DOE, a tool life test of gundrills, is considered in detail.
Experimental Evaluation of Longitudinal Seismic Performance of Bridge Restrainers at In-Span Hinges
Authors: Vlassis AG , Maragakis E , Saiidi M
Published: May 2004

A specimen consisting of two box girder reinforced concrete blocks representing the adjacent spans of a reference bridge at an in-span hinge was constructed and tested under incrementally increasing input excitation to investigate the impact between adjacent bridge spans at in-span hinges, to evaluate the efficacy of restrainers in reducing relative displacements across the hinges, and to examine the effects of restrainer stiffness and gap on the response of the hinge-restrainer system. Cable restrainers were used to connect the two blocks, the number and gap of which were varied during the experiments. The experimental results indicated that impacts between the adjacent frames produce acceleration levels significantly higher than what is typically assumed in design. In all the restrained system cases, restrainers were capable of reducing hinge relative displacements and preventing span unseating. However, restrainer yielding occurred under strong input motions, especially when the restrainer gap was set to zero.
Detecting Overload from Strain Information during Fatigue Crack Propagation under Negative Stress Ratio
Authors: Makabe Chobin , Purnowidodo Anindito , Sueyoshi Toshiyasu , Utsunomiya Takao
Published: May 2004

In the present study, a detection method of an overload application during stress cycles under constant amplitude was investigated. Also, the effect of the tensile overload was shown at three stress ratios: R = 0, -1, and -1.5, to understand the effects of R on crack propagation after an overload. At the baseline of R = 0, after the overload, retardation in the crack propagation was observed, and the crack growth rate decreased. However, in the case of R = -1.5, the fatigue crack growth rate actually accelerated after the tensile overload. The detection of that crack propagation behavior was attempted through the information of the strain waveform h; h = εy + 1.2λx, where εx and εy are the local strains at the specimen axis, and λ is the strain range ratio Δεy/Δεx. The waveform shape of h was changed after the overloading. Also, the application of the overload could be detected by the variation of the strain range ratio λ. Especially, the present method is useful for cases of the crack propagation stage under negative R conditions.
Methodology for Determination of Electrical Properties of Soils
Authors: Rohini K , Singh DN
Published: May 2004

Efforts were made to determine electrical resistivity, capacitance, and dielectric constant of the soil mass, by conducting experiments on silty soil and white clay samples, compacted at various dry densities, water contents, and saturations. To achieve this an impedance cell and a time-domain reflectometry probe were used. Based on the study, relationships between resistivity and capacitance, with respect to saturation, dry density, and water content are developed, and the dielectric constant of the soil mass is determined. These results exhibit an excellent match with results reported in the literature. The study demonstrates the utility of the developed methodology for determining electrical properties of soils, easily and rapidly.
An Analysis of the Neural Representation of Birdsong Memory
Authors: Terpstra Nienke J. , Bolhuis Johan J. , den Boer-Visser Ardie M.
Published: May 2004

Songbirds, such as zebra finches, learn their song from a tutor early in life. Forebrain nuclei in the “song system” are important for the acquisition and production of song. Brain regions [including the caudomedial part of the neostriatum (NCM) and of the hyperstriatum ventrale (CMHV)] outside the song system show increased neuronal activation, measured as expression of immediate early genes (IEGs), when zebra finch males are exposed to song. IEG expression in the NCM in response to tutor song is significantly positively correlated with the strength of song learning (i.e., the number of elements copied). Here, we exposed three groups of adult zebra finch males to tutor song, to their own song, or to novel conspecific song. The two control groups were included to examine an alternative explanation of our previous results in terms of variation in predisposed levels of attentiveness. Expression of Zenk, the protein product of the IEGZENK, was measured in the NCM, CMHV, and hippocampus. There were no significant differences in overall Zenk expression between the three experimental groups. However, there was a significant positive correlation between Zenk expression in the NCM (but not in the other two regions) and strength of song learning in the males that were exposed to the tutor song. There was no such correlation in the other two groups. These results suggest that experience-related neuronal activation is specific to the tutor song and thus unlikely to be a result of differences in attention.
Firing Mode-Dependent Synaptic Plasticity in Rat Neocortical Pyramidal Neurons
Authors: Birtoli Barbara , Ulrich Daniel
Published: May 2004

Pyramidal cells in the mammalian neocortex can emit action potentials either as series of individual spikes or as distinct clusters of high-frequency bursts. However, why two different firing modes exist is largely unknown. In this study, we report that in layer V pyramidal cells of the rat somatosensory cortex,in vitroassociations of EPSPs with spike bursts delayed by +10 msec led to long-term synaptic depression (LTD), whereas pairings with individual action potentials at the same delay induced long-term potentiation. EPSPs were evoked extracellularly in layer II-III and recorded intracellularly in layer V neurons with the whole-cell or nystatin-based perforated patch-clamp technique. Bursts were evoked with brief somatic current injections, resulting in three to four action potentials with interspike frequencies of ∼200 Hz, characteristic of intrinsic burst firing. Burst-firing-associated LTD (Burst-LTD) was robust over a wide range of intervals between -100 and +200 msec, and depression was maximal (∼50%) for closely spaced presynaptic and postsynaptic events. Burst-LTD was associative and required concomitant activation of low voltage-activated calcium currents and metabotropic glutamate receptors. Conversely, burst-LTD was resistant to blockade of NMDA receptors or inhibitory synaptic potentials. Burst-LTD was also inducible at already potentiated synapses. We conclude that intrinsic burst firing represents a signal for resetting excitatory synaptic weights.
An Oligodendrocyte Lineage-Specific Semaphorin, Sema5A, Inhibits Axon Growth by Retinal Ganglion Cells
Authors: Goldberg Jeffrey L. , Vargas Mauricio E. , Wang Jack T. , Mandemakers Wim , Oster Stephen F. , Sretavan David W. , Barres Ben A.
Published: May 2004

In the mammalian CNS, glial cells repel axons during development and inhibit axon regeneration after injury. It is unknown whether the same repulsive axon guidance molecules expressed by glia and their precursors during development also play a role in inhibiting regeneration in the injured CNS. Here we investigate whether optic nerve glial cells express semaphorin family members and, if so, whether these semaphorins inhibit axon growth by retinal ganglion cells (RGCs). We show that each optic nerve glial cell type, astrocytes, oligodendrocytes, and their precursor cells, expressed a distinct complement of semaphorins. One of these, sema5A, was expressed only by purified oligodendrocytes and their precursors, but not by astrocytes, and was present in both normal and axotomized optic nerve but not in peripheral nerves. Sema5A induced collapse of RGC growth cones and inhibited RGC axon growth when presented as a substratein vitro. To determine whether sema5A might contribute to inhibition of axon growth after injury, we studied the ability of RGCs to extend axons when cultured on postnatal day (P) 4, P8, and adult optic nerve explants and found that axon growth was strongly inhibited. Blocking sema5A using a neutralizing antibody significantly increased RGC axon growth on these optic nerve explants. These data support the hypothesis that sema5A expression by oligodendrocyte lineage cells contributes to the glial cues that inhibit CNS regeneration.
Dose Conversion from Recombinant Human Erythropoietin to Darbepoetin alfa: Recommendations From Clinical Studies
Authors: Scott Shane D.
Published: May 2004

Recombinant human erythropoietin (r‐HuEPO, epoetin alfa), is an established and effective treatment for anemia associated with both chronic kidney disease (CKD) and cancer and has improved the management of anemia over alternatives such as transfusion. Darbepoetin alfa is a new erythropoietic agent with a 3‐fold longer half‐life and increased in vivo potency relative to r‐HuEPO. These properties allow patients to be treated with longer dosing intervals than with r‐HuEPO. Relative potency between r‐HuEPO and darbepoetin alfa is not a fixed relationship but is dependent on several factors. Clinical study results suggest that greater relative potency differences are seen between r‐HuEPO and darbepoetin alfa when the dosing intervals are longer and when r‐HuEPO dose requirements are higher. Although 200 U of r‐HuEPO contains the same peptide mass as 1 μg of darbepoetin alfa, a fixed ratio of 200:1 does not necessarily predict an appropriate dose conversion between the two drugs across the entire spectrum of dose ranges. When converting patients with CKD from r‐HuEPO to darbepoetin alfa, dosing should be based on relevant clinical data. Appropriate guidance for conversion of patients with CKD from r‐HuEPO to darbepoetin alfa is provided in the approved United States package insert for darbepoetin alfa. In patients who are prescribed darbepoetin alfa, either by conversion from r‐HuEPO or as de novo treatment, therapy should begin according to recommendations in the package insert, after which, doses should be titrated individually according to each patient's hemoglobin response. Dosing data from oncology clinical studies, although not necessarily applicable to CKD, indicate similar potency ratios between r‐HuEPO and darbepoetin alfa, and in addition affirm the finding that, as the interval between doses of darbepoetin alfa is increased, hemoglobin response is maintained.
Infant with severe penicillamine embryopathy born to a woman with Wilson disease
Authors: Pinter R. , Hogge W.A. , McPherson E.
Published: May 2004

We report a chromosomally normal infant boy with congenital diffuse cutis laxa, severe micrognathia, contractures of all limbs, and central nervous system abnormalities including agenesis of the corpus callosum, born to a woman taking D‐penicillamine (DP) for Wilson disease (WD) throughout her pregnancy. His postnatal course was remarkable for chronic lung disease, profound developmental delays, and probable cortical blindness, as well as resolution of his cutis laxa. Embryopathy is a rare complication in babies born to pregnant women treated with DP, and there have been only seven previous reports of birth defects in exposed infants (three of which had favorable postnatal outcomes). The etiology of the severe outcome in this boy is unclear, but prenatal measurement of maternal copper and zinc levels may be indicated for management. © 2004 Wiley‐Liss, Inc.
Phenotypic and molecular variability of the holoprosencephalic spectrum
Authors: Lazaro Leila , Dubourg Christéle , Pasquier Laurent , Duff Franck Le , Blayau Martine , Durou Marie‐Renée , Pintière Armelle Thomas de la , Aguilella Céline , David Véronique , Odent Sylvie
Published: May 2004

Since 1996, a European network has been organized from Rennes, France and holoprosencephalic files were collected for clinical and molecular study. Familial instances of typical and atypical holoprosencephaly (HPE) were found in 30% of cases. All affected children had psychomotor delay with microcephaly, often associated with endocrine, digestive, and respiratory abnormalities, and thermal dysregulation. Among 173 subjects in the molecular study, 28 heterozygous mutations were identified (16%): 15 SHH mutations, 6 ZIC2 mutations, 5 SIX3 mutations, and 2 TGIF mutations. © 2004 Wiley‐Liss, Inc.
Further evidence of a combined effect of SERTPR and TPH on SSRIs response in mood disorders
Authors: Serretti Alessandro , Cusin Cristina , Rossini David , Artioli Paola , Dotoli Danilo , Zanardi Raffaella
Published: May 2004

We reported an independent association of the short variant of the serotonin transporter gene‐linked polymorphic region (SERTPR) and tryptophan hydroxylase (TPH) genes with antidepressant response to selective serotonin reuptake inhibitors (SSRIs). The aim of the present study was to confirm the effect of the SERTPR and TPH gene variants on the SSRIs antidepressant activity in a new sample of major and bipolar depressives. Two hundred and twenty one inpatients (major depressives = 128, bipolar disorder = 93) were treated with SSRIs (fluvoxamine or paroxetine) for 6 weeks; the severity of depressive symptoms was weekly assessed with the Hamilton Rating Scale for Depression (HAMD). SERTPR and TPH variants were determined using PCR‐based techniques, 220 subjects genotyped for SERTPR and 221 for TPH that were never included in previous studies. SERTPR*s/s variant association with a poor response to SSRI treatment was confirmed, even if with less significant P values (P = 0.034), independently from clinical variables; pooling the present sample with previous ones we observed a highly significant effect (P < 0.000001). TPH*A/A variants showed higher HAMD scores throughout the trial but with only a trend in the same direction of our previous study in terms of a worse response of A/A genotypes. Thus, the previous positive association was not fully replicated for TPH. The present independent replication confirms SERTPR variants as a liability factor for antidepressant efficacy while the TPH effect is not unequivocal. © 2004 Wiley‐Liss, Inc.
Long‐term results of bilateral pallidal stimulation in Parkinson's disease
Authors: Volkmann Jens , Allert Niels , Voges Jürgen , Sturm Volker , Schnitzler Alfons , Freund Hans‐Joachim
Published: May 2004

We followed up 11 patients for up to 5 years after bilateral pallidal deep brain stimulation for advanced Parkinson's disease. Dyskinesias remained significantly reduced until the last assessment. The initial improvement of off‐period motor symptoms and fluctuations, however, was not sustained and gradually declined. Beneficial effects of pallidal deep brain stimulation on activities of daily living in the on‐ and off‐period were lost after the first year. Replacement of pallidal electrodes into the subthalamic nucleus in four patients could restore the initial benefit of deep brain stimulation and allowed a significant reduction of dopaminergic drug therapy.
A critical period for prevention of posttraumatic neocortical hyperexcitability in rats
Authors: Graber Kevin D. , Prince David A.
Published: May 2004

Penetrating cortical trauma frequently results in delayed development of epilepsy. In the rat undercut model of neocortical posttraumatic hyperexcitability, suppression of neuronal activity by exposing the injured cortex to tetrodotoxin (TTX) in vivo for approximately 2 weeks prevents the expression of abnormal hypersynchronous discharges in neocortical slices. We examined the relationship between neuronal activity during the latent period after trauma and subsequent expression of hyperexcitability by varying the timing of TTX treatment. Partially isolated islands of rat sensorimotor cortex were treated with Elvax polymer containing TTX to suppress cortical activity and slices obtained for in vitro experiments 10 to 15 days later. TTX treatment was either started immediately after injury and discontinued after a variable number of days or delayed for a variable time after the lesion was placed. Immediate treatment lasting only 2 to 3 days and treatment delayed up to 3 days prevented hyperexcitability. Thus, there is a critical period for development of hyperexcitability in this model that depends on cortical activity. We propose that the hyperexcitability caused by partial cortical isolation may represent an early stage of posttraumatic epileptogenesis. A hypothetical cascade of events leading to subsequent pathophysiological activity is likely initiated at the time of injury but remains plastic during this critical period. Ann Neurol 2004;55:860–870
Stability and Dynamics of Domain‐Swapped Bovine‐Seminal Ribonuclease
Authors: Chakrabarti Kalyan S. , Sanjeev B. S. , Vishveshwara Saraswathi
Published: May 2004

The proteins of the ribonuclease‐A (RNase‐A) family are monomeric, with the exception of bovine‐seminal ribonuclease (BS‐RNase). BS‐RNase is formed by swapping the N‐terminal helices across the two monomeric units. A molecular‐dynamics (MD) study has been performed on the protein for a simulation time of 5.5 ns to understand the factors responsible for the stability of the dimer. Essential dynamics analysis and motional correlation of the protein atoms yielded the picture of a stabilising, yet flexible, interface. We have investigated the role of intermolecular H‐bonding, protein/water interaction, and protein/water networks in stabilising the dimer. The networks of interchain H‐bonds involving side‐chain/side‐chain or side‐chain/main‐chain (ScHB) interactions between the two chains have also been studied. The ability of protein atoms in retaining particular H2O molecules was investigated as a function of the accessible surface area (ASA), depth, and hydration parameters, as well as their participation in protein/water networks.
Mutational Analysis of a Key Residue in the Substrate Specificity of a Cephalosporin Acylase
Authors: Otten Linda G. , Sio Charles F. , van der Sloot Almer M. , Cool Robbert H. , Quax Wim J.
Published: May 2004

β‐Lactam acylases are crucial for the synthesis of semisynthetic cephalosporins and penicillins. Unfortunately, there are no cephalosporin acylases known that can efficiently hydrolyse the amino‐adipic side chain of Cephalosporin C. In a previous directed evolution experiment, residue Asn266 of the glutaryl acylase from Pseudomonas SY‐77 was identified as being important for substrate specificity. In order to explore the function of this residue in substrate specificity, we performed a complete mutational analysis of position 266. Codons for all amino acids were introduced in the gene, 16 proteins that could be functionally expressed in Escherichia coli were purified to homogeneity and their catalytic parameters were determined. The mutant enzymes displayed a broad spectrum of affinities and activities, pointing to the flexibility of the enzyme at this position. Mutants in which Asn266 was changed into Phe, Gln, Trp and Tyr displayed up to twofold better catalytic efficiency (kcat/Km)than the wild‐type enzyme when adipyl‐7‐aminodesacetoxycephalosporanic acid (adipyl‐7‐ADCA) was used as substrate, due to a decreased Km. Only mutants SY‐77N266H and SY‐77N266M showed an improvement of both catalytic parameters, resulting in 10‐ and 15‐times higher catalytic efficiency with adipyl‐7‐ADCA, respectively. Remarkably, the catalytic activity (kcat) of SY‐77N266M when using adipyl‐7‐ADCA as substrate was as high as when glutaryl‐7‐aminocephalosporanic acid (glutaryl‐7‐ACA) was used, and approaches commercially interesting activity. SY‐77N266Q, SY‐77N266H and SY‐77N266M mutants showed a modest improvement in hydrolysing Cephalosporin C. Since these mutants also have a good catalytic efficiency when adipyl‐7‐ADCA is used and are still active towards glutaryl‐7‐ACA, they can be regarded as broad substrate acylases. These results demonstrate that the combination of directed evolution for the identification of important positions, together with saturation mutagenesis for finding the optimal amino acid, is a very effective method for finding improved biocatalysts.
Biosynthesis of Volatiles by the MyxobacteriumMyxococcus xanthus
Authors: Dickschat Jeroen S. , Wenzel Silke C. , Bode Helge B. , Müller Rolf , Schulz Stefan
Published: May 2004

The volatiles emitted from cell cultures of myxobacteriumMyxococcus xanthuswere collected by use of a closed‐loop stripping apparatus (CLSA) and analyzed by GC‐MS. Two new natural products, (S)‐9‐methyldecan‐3‐ol ((S)‐1) and 9‐methyldecan‐3‐one (2), were identified and synthesized, together with other aliphatic ketones and alcohols, and terpenes. Biosynthesis of the two main components (S)‐1and2was examined in feeding experiments carried out with the wild‐type strain DK1622 and two mutant strains JD300 and DK11017, which are impaired in the degradation pathway from leucine to isovaleryl‐SCoA. Isovaleryl‐SCoA is used as a starter, followed by chain elongation with two malonate units. Subsequent use of methyl malonate and decarboxylation leads to (S)‐1and2. Furthermore, 3,3‐dimethylacrylic acid (DMAA) can be used by the mutant strain to form isovaleryl‐SCoA, which corroborates recent data on the detection of a novel variety of the mevalonate pathway giving rise to isovaleryl‐SCoA from HMGCoA.
Biocatalytic Asymmetric Rearrangement of a Methylene‐Interrupted Bis‐epoxide: Simultaneous Control of Four Asymmetric Centers Through a Biomimetic Reaction Cascade
Authors: Glueck Silvia M. , Fabian Walter M. F. , Faber Kurt , Mayer Sandra F.
Published: May 2004

Asymmetric enzyme‐catalyzed hydrolysis of methylene‐interrupted bis‐epoxides 1 a and 1 b catalyzed by bacterial epoxide hydrolases furnished tetrahydrofuran derivatives 2 a and 2 b through a hydrolysis–rearrangement cascade. Whereas racemic bis‐oxiranes 1 b–d underwent kinetic resolution with moderate stereoselectivities to yield products with up to 92 % ee and 66 % de: meso‐bis‐oxirane cis,cis‐1 a was transformed into (6R,7R,9S,10S)‐2 a in 94 % ee and 89 % de at high conversion (85 %) by Rhodococcus sp. CBS 717.73 as the major product. The reaction sequence resembles a biomimetic reaction cascade and provides an efficient entry into the structural core of annonaceous acetogenins with simultaneous control of four stereocenters.
The Immunogenicity of the Tumor‐Associated Antigen Lewisy May Be Suppressed by a Bifunctional Cross‐Linker Required for Coupling to a Carrier Protein
Authors: Buskas Therese , Li Yanhong , Boons Geert‐Jan
Published: May 2004

A Lewisy (Ley) tetrasaccharide modified by an artificial aminopropyl spacer was synthesized by a highly convergent approach that employed a levulinoyl ester and a 9‐fluorenylmethoxycarbonate for temporary protection of the hydroxy groups and a trichloroethyloxycarbonyl as an amino protecting group. The artificial aminopropyl moiety was modified by a thioacetyl group, which allowed efficient conjugation to keyhole limpet hemocyanin (KLH) modified by electrophilic 4‐(maleimidomethyl)cyclohexane‐1‐carboxylate (MI). Mice were immunized with the KLH–MI–Ley antigen. A detailed analysis of sera by ELISA established that a strong immunoglobulin G (IgG) antibody response was elicited against the linker region. The use of a smaller and more flexible 3‐(bromoacetamido)propionate for the attachment of Ley to KLH not only reduced the IgG antibody response against the linker but also led to a significantly improved immune response against the Ley antigen. This study shows that highly antigenic linkers suppress antibody responses to weak antigens such as self‐antigens.
Heavy Alkaline Earth Metal Pyrazolates: Synthetic Pathways, Structural Trends, and Comparison with Divalent Lanthanoids
Authors: Hitzbleck Julia , O'Brien Anna Y. , Forsyth Craig M. , Deacon Glen B. , Ruhlandt‐Senge Karin
Published: May 2004

Two series of heavy alkaline earth metal pyrazolates, [M(Ph2pz)2(thf)4] 1 a–c (Ph2pz=3,5‐diphenylpyrazolate, M=Ca, Sr, Ba; THF=tetrahydrofuran) and [M(Ph2pz)2(dme)n] (M=Ca, 2 a, Sr, 2 b, n=2; M=Ba, 2 c, n=3; DME=1,2‐dimethoxyethane) have been prepared by redox transmetallation/ligand exchange utilizing Hg(C6F5)2. Compounds 1 a and 2 b were also obtained by redox transmetallation with Tl(Ph2pz). Alternatively, direct reaction of the alkaline earth metals with 3,5‐diphenylpyrazole at elevated temperatures under solventless conditions yielded compounds 1 a–c and 2 a–c upon extraction with THF or DME. By contrast, [M(Me2pz)2(Me2pzH)4] 3 a–c (M=Ca, Sr, Ba; Me2pzH=3,5‐dimethylpyrazole) were prepared by protolysis of [M{N(SiMe3)2}2(thf)2] (M=Ca, Sr, Ba) with Me2pzH in THF and by direct metallation with Me2pzH in liquid NH3/THF. Compounds 1 a–c and 2 a–c display η2‐bonded pyrazolate ligands, while 3 a,b exhibit η1‐coordination. Complexes 1 a–c have transoid Ph2pz ligands and an overall coordination number of eight with a switch from mutually coplanar Ph2pz ligands in 1 a,b to perpendicular in 1 c. In eight coordinate 2 a,b the pyrazolate ligands are cisoid, whilst 2 c has an additional DME ligand and a metal coordination number of ten. By contrast, 3 a,b have octahedral geometry with four η1‐Me2pzH donors, which are hydrogen‐bonded to the uncoordinated nitrogen atoms of the two trans Me2pz ligands. The application of synthetic routes initially developed for the preparation of lanthanoid pyrazolates provides detailed insight into the similarities and differences between the two groups of metals and structures of their complexes.
Separation‐Friendly Mitsunobu Reactions: A Microcosm of Recent Developments in Separation Strategies
Authors: Dandapani Sivaraman , Curran Dennis P.
Published: May 2004

The Mitsunobu reaction is famous for its scope and power, but infamous for its separation headaches. Typically, the target product is enticed away from the reagent‐derived byproducts by careful chromatography. The use of polymer‐bound Mitsunobu reagents solves only half of the problem, because polymer‐bound diethyl azodicarboxylate (DEAD) and phosphine reagents cannot be employed simultaneously. This article classifies, compares, and contrasts various emerging strategies for product isolation in Mitsunobu reactions. Because so many different strategies have been used, the Mitsunobu reaction is a microcosm for the new field of strategy level separations.
Vinculin is proteolyzed by calpain during platelet aggregation: 95 kDa cleavage fragment associates with the platelet cytoskeleton
Authors: Serrano Katherine , Devine Dana V.
Published: May 2004

The focal adhesion protein vinculin contributes to cell attachment and spreading through strengthening of mechanical interactions between cell cytoskeletal proteins and surface membrane glycoproteins. To investigate whether vinculin proteolysis plays a role in the influence vinculin exerts on the cytoskeleton, we studied the fate of vinculin in activated and aggregating platelets by Western blot analysis of the platelet lysate and the cytoskeletal fractions of differentially activated platelets. Vinculin was proteolyzed into at least three fragments (the major one being ∼95 kDa) within 5 min of platelet activation with thrombin or calcium ionophore. The 95 kDa vinculin fragment shifted cellular compartments from the membrane skeletal fraction to the cortical cytoskeletal fraction of lysed platelets in a platelet aggregation‐dependent manner. Vinculin cleavage was inhibited by calpeptin and E64d, indicating that the enzyme responsible for vinculin proteolysis is calpain. These calpain inhibitors also inhibited the translocation of full‐length vinculin to the cytoskeleton. We conclude that cleavage of vinculin and association of vinculin cleavage fragment(s) with the platelet cytoskeleton is an activation response that may be important in the cytoskeletal remodeling of aggregating platelets. Cell Motil. Cytoskeleton 58:242–252, 2004. © 2004 Wiley‐Liss, Inc.
Curcumin inhibits cell motility and alters microfilament organization and function in prostate cancer cells
Authors: Holy Jon
Published: May 2004

Curcumin is a dietary phytochemical associated with anti‐tumorigenic effects, but the mechanisms by which it inhibits cancer cell growth and metastasis are not completely understood. For example, little information is available regarding the effects of curcumin on cytoskeletal organization and function. In this study, time‐lapse video and immunofluorescence labeling methods were used to demonstrate that curcumin significantly alters microfilament organization and cell motility in PC‐3 and LNCaP human prostate cancer cells in vitro. Curcumin rapidly arrests cell movements and subsequently alters cell shape in the highly motile PC‐3 cell line, but has a less noticeable effect on the relatively immobile LNCaP cell line. Stress fibers are augmented, and the overall quantity of f‐actin appears to increase in both types of cells following curcumin treatment. Cytochalasin B (CB) disrupts microfilament organization in both cell lines, and causes vigorous membrane blebbing in PC‐3 cells, but not LNCaP cells. Pre‐treatment of cells with curcumin suppresses changes in microfilament organization caused by CB, and blocks PC‐3 membrane blebbing. At least some of the effects of curcumin appear to be mediated by protein kinase C (PKC), as treatment with the PKC inhibitor bisindolylmaleimide inhibits the ability of curcumin to block CB‐induced membrane blebbing. These findings demonstrate that curcumin exerts significant effects on the actin cytoskeleton in prostate cancer cells, including altering microfilament organization and function. This is a novel observation that may represent an important mechanism by which curcumin functions as a chemopreventative agent, and as an inhibitor of angiogenesis and metastasis. Cell Motil. Cytoskeleton 58:253–268, 2004. © 2004 Wiley‐Liss, Inc.
Reducing the time interval between cycles using standard doses of docetaxel and lenogastrim support
Authors: Culine Stéphane , Romieu Gilles , Fabbro Michel , Becht Catherine , Cupissol Didier , Guillemare Catherine , Bleuse Jean‐Pierre , Lotz Véronique , Gourgou Sophie
Published: May 2004

BACKGROUND

As a single agent, 100 mg/m2 of docetaxel every 3 weeks remains the standard schedule in the first‐line treatment for metastatic disease. At this dose level, the major limiting toxicity is neutropenia. The current study was conducted to assess the feasibility of reducing time intervals between cycles while delivering standard doses of docetaxel with granulocyte–colony‐stimulating factor (G‐CSF; lenograstim).

METHODS

In the first part of the study, 24 patients were randomized to receive 1 of 4 schedules: 100 mg/m2 of docetaxel every 21 days without lenograstim; 100 mg/m2 of docetaxel every 18 days with lenograstim; 100 mg/m2 of docetaxel every 14 days with lenograstim; or 100 mg/m2 of docetaxel every 10 days with lenograstim. In the second part of the study, 15 additional patients were included to confirm the feasibility of the recommended interval between cycles.

RESULTS

Of the 39 patients treated, 14 patients (36%) withdrew from therapy because of Grade 3 (according to standard World Health Organization criteria) nonhematologic limiting toxicities. Only 3 patients were treated in the 10‐day interval arm and were withdrawn because of toxicity—1 patient had Grade 3 asthenia after the second cycle and 2 patients had Grade 3 dermatitis after 4 cycles. Of the 24 patients treated in the 14‐day intervals, Grade 3 limiting toxicities occurred in 8 patients (33%), including dermatitis in 3 patients; diarrhea, myalgia/arthralgia, or asthenia in 4 patients; and ungual toxicity in 1 patient.

CONCLUSIONS

Introduction of G‐CSF (lenograstim) as primary prophylaxis allowed the administration of docetaxel every 14 days with manageable toxicities. Further studies are now required to assess the impact in terms of response rates and survival in patients with cancer. Cancer 2004. © 2004 American Cancer Society.
Differential expression of 5HT‐1A, α1b adrenergic, CRF‐R1, and CRF‐R2 receptor mRNA in serotonergic, γ‐aminobutyric acidergic, and catecholaminergic cells of the rat dorsal raphe nucleus
Authors: Day Heidi E.W. , Greenwood Benjamin N. , Hammack Sayamwong E. , Watkins Linda R. , Fleshner Monika , Maier Steven F. , Campeau Serge
Published: May 2004

The dorsal raphe nucleus (DR) has a topographic neuroanatomy consistent with the idea that different parts of this nucleus subserve different functions. Here we use dual in situ hybridization to describe the rostral‐caudal neurochemical distribution of three major cell groups, serotonin (5‐hydroxytryptamine; 5‐HT), γ‐aminobutyric acid (GABA), and catecholamine, and their relative colocalization with each other and mRNA encoding four different receptor subtypes that have been described to influence DR responses, namely, 5HT‐1A, α1b adrenergic (α1b ADR), and corticotropin‐releasing factor type 1 (CRF‐R1) and 2 (CRF‐R2) receptors. Serotonergic and GABAergic neurons were distributed throughout the rostral‐caudal extent of the DR, whereas catecholaminergic neurons were generally restricted to the rostral half of the nucleus. These phenotypes essentially represent distinct cell populations, because the neurochemical markers were rarely colocalized. Both 5HT‐1A and α1b ADR mRNA were highly expressed throughout the DR, and the vast majority of serotonergic neurons expressed both receptors. A smaller percentage of GABAergic neurons also expressed 5HT‐1A or α1b ADR mRNA. Very few catecholaminergic cells expressed either 5HT‐1A or α1b ADR mRNA. CRF‐R1 mRNA was detected only at very low levels within the DR, and quantitative colocalization studies were not technically feasible. CRF‐R2 mRNA was mainly expressed at the middle and caudal levels of the DR. At midlevels, CRF‐R2 mRNA was expressed exclusively in serotonin neurons, whereas, at caudal levels, approximately half the CRF‐R2 mRNA was expressed in GABAergic neurons. The differential distribution of distinct neurochemical phenotypes lends support to the idea of functional differentiation of the DR. J. Comp. Neurol. 474:364–378, 2004. © 2004 Wiley‐Liss, Inc.
Expression ofDbx1,Neurogenin 2,Semaphorin 5A,Cadherin 8, andEmx1distinguish ventral and lateral pallial histogenetic divisions in the developing mouse claustroamygdaloid complex
Authors: Medina Loreta , Legaz Isabel , González Gertrudis , De Castro Fernando , Rubenstein John L.R. , Puelles Luis
Published: May 2004

We studied the lateral and ventral pallial divisions of the claustroamygdaloid complex by means of analysis of expression patterns of the developmental regulatory genesTbr1,Dbx1,Neurogenin 2,Emx1,Cadherin 8, andSemaphorin 5Ain mouse developing telencephalon, from embryonic day 12.5 until birth. Our results indicate that these genes help to distinguish distinct lateral and ventral pallial histogenetic divisions in the embryonic telencephalon.Tbr1is broadly expressed in both lateral and ventral pallial histogenetic divisions (the lateroventral migratory stream plus the mantle) during early and intermediate embryonic development; its signal becomes weak in parts of the mantle during late embryonic development.Dbx1is strongly and specifically expressed in progenitor cells (ventricular zone) of the ventral pallium during early embryonic development, but there is no signal of this gene in the rest of the pallium nor the subpallium.Neurogenin 2andSemaphorin 5Aare both expressed in a ventral subdivision of the lateroventral migratory stream (called by us the ventral migratory stream). Further, specific nuclei of the claustral complex and pallial amygdala show strong expression ofNeurogenin 2and/orSemaphorin 5A, including the ventromedial claustrum and endopiriform nuclei, the lateral and basomedial amygdalar nuclei, the anterior and posteromedial cortical amygdalar areas, plus the amygdalo‐hippocampal area. We interpret these nuclei or areas of the claustroamygdaloid complex as possible derivatives of the ventral pallium. In contrast, during embryonic development the dorsolateral claustrum, the basolateral amygdalar nucleus, and the posterolateral cortical amygdalar area do not express or show weak expression ofNeurogenin 2orSemaphorin 5A, but express selectively and stronglyCadherin 8plusEmx1, and may be derivatives of the lateral pallium. The lateral pallial and ventral pallial divisions of the claustroamygdaloid complex appear to have some different sets of connections, although this requires further investigation. J. Comp. Neurol. 474:504–523, 2004. © 2004 Wiley‐Liss, Inc.
Peptidomics of CNS‐associated neurohemal systems of adult Drosophila melanogaster: A mass spectrometric survey of peptides from individual flies
Authors: Predel Reinhard , Wegener Christian , Russell William K. , Tichy Shane E. , Russell David H. , Nachman Ronald J.
Published: May 2004

Neuropeptides are important messenger molecules that influence nearly all physiological processes. In insects, they can be released as neuromodulators within the central nervous system (CNS) or as neurohormones into the hemolymph. We analyzed the peptidome of neurohormonal release sites and associated secretory peptidergic neurons of adult Drosophila melanogaster. MALDI‐TOF mass spectrometric analyzes were performed on single organs or cell cluster from individual flies. This first peptidomic characterization in adult fruit flies revealed 32 different neuropeptides. Peptides not directly predictable from previously cloned or annotated precursor genes were sequenced by tandem mass spectrometry. These peptides turned out to be either intermediate products of neuropeptide processing or shorter versions of known peptides. We found that the peptidome of the CNS‐associated neurohemal organs is tagma‐specific in Drosophila. Abdominal neurohemal organs and their supplying peptidergic neurons contain the capa gene products periviscerokinins and pyrokinin‐1, thoracic neurohemal organs contain FMRFamides, and the neurohemal release sites of the brain contain pyrokinin‐12‐15, pyrokinin‐2, corazonin, myosuppressin, and sNPF as their major putative release products. Our results show that peptidomic approaches are well suited to study differential neuropeptide expression or posttranslational modifications in morphologically defined parts of the nervous system and in a developmental and physiological context in animals as small as Drosophila melanogaster. J. Comp. Neurol. 474:379–392, 2004. © 2004 Wiley‐Liss, Inc.
Development and morphology of Class II Kenyon cells in the mushroom bodies of the honey bee, Apis mellifera
Authors: Farris Sarah M. , Abrams Andrew I. , Strausfeld Nicholas J.
Published: May 2004

Class II Kenyon cells, defined by their early birthdate and unique dendritic arborizations, have been observed in the mushroom bodies of evolutionarily divergent insects. In the fruit fly Drosophila melanogaster, Class II (also called clawed) Kenyon cells are well known for their extensive reorganization that occurs during metamorphosis. The present account reports for the first time the occurrence of mushroom body reorganization during metamorphosis in holometabolous insect species outside of the Diptera. In the honey bee, Apis mellifera, Class II Kenyon cells show signs of degeneration and undergo a subtle reshaping of their axons during metamorphosis. Unlike in Drosophila, reorganization of Class II Kenyon cells in the honey bee does not involve the loss of axon branches. In contrast, the mushroom bodies of closely related hymenopteran species, the polistine wasps, undergo a much more dramatic restructuring near the end of metamorphosis. Immunohistochemistry, dextran fills, and Golgi impregnations illuminate the heterogeneous nature of Class II Kenyon cells in the developing and adult honey bee brain, with subpopulations differing in the location of dendritic arbors within the calyx, and branching pattern in the lobes. Furthermore, polyclonal antibodies against the catalytic subunit of Drosophila protein kinase A (anti‐DC0) label an unusual and previously undescribed trajectory for these neurons. The observed variations in morphology indicate that subpopulations of Class II Kenyon cells in the honey bee can likely be further defined by significant differences in their specific connections and functions within the mushroom bodies. J. Comp. Neurol. 474:325–339, 2004. © 2004 Wiley‐Liss, Inc.