bluuebunny/crossref_metadata_2025 huggingface dataset:
Catalytic features of monoclonal antibody i41SL1‐2 subunits
Authors: Hifumi Emi , Kondo Hiroyuki , Mitsuda Yukie , Uda Taizo
Published: October 2003

A monoclonal antibody (mAb), i41SL1‐2, was obtained by immunizing the peptide of complementarity‐determining region‐1 (CDRL‐1: RSSKSLLYSNGNTYLY) of a super catalytic antibody light chain, 41S‐2‐L, capable of enzymatically destroying the gp41 molecule of the HIV‐1 envelope. From the DNA and the deduced amino acid sequences of the light and heavy chain of i41SL1‐2 mAb, molecular modeling was conducted that suggested that both subunits of i41SL1‐2 mAb possess catalytic triads in their structures. Especially the light chain of i41SL1‐2 mAb possesses a characteristic catalytic triad composed of Asp1, Ser27A, and His93, whose positions are identical to the catalytic antibody light chain, VIPase, of S. Paul and colleagues (see text). The antibody gene of i41SL1‐2 light chain and VIPase belong to the same germline, bd2, suggesting that the discrete germline inherently possesses catalytic activity. Both light and heavy chains of i41SL1‐2 mAb degraded the antigenic peptide CDRL‐1 within 47 and 57 h, respectively. The catalytic reaction constant (kcat) of the light and heavy chain was 6.1 × 10−1 and 6.2 × 10−1 min−1, respectively. These are high values for the natural catalytic antibodies reported so far. The catalytic efficiency (kcat/Km) of the light and heavy chain was 3.1 × 105 and 4.9 × 104 M−1 min−1, respectively. The first cleaved bond of the antigenic peptide by subunits of i41SL1‐2 mAb was between Arg1 and Ser2 in the sequence of CDRL‐1, suggesting a serine protease character. © 2003 Wiley Periodicals. Biotechnol Bioeng 84: 485–493, 2003.
Dynamic behavior of adsorber membranes for protein recovery
Authors: Avramescu Maria‐Elena , Borneman Zandrie , Wessling Matthias
Published: October 2003

In recent years there has been a considerable interest in developing membrane chromatography systems that function as a short, wide chromatographic column in which the adsorptive packing consists of one or more microporous membranes. This study reports the use of new adsorber membranes prepared by the incorporation of various types of ion exchange resins into an EVAL porous membrane for protein recovery. The obtained heterogeneous matrixes composed of solid particles surrounded by the polymeric film possess a good accessibility for the protein to the adsorptive sites. Furthermore, small particles can be embedded into porous polymeric structures without the disadvantages of classical chromatographic columns (high pressure drop, fouling and plugging sensitivity, low flow rate), but with the advantages of membrane technology (easy scale‐up, low‐pressure drop, high flow rate). The adsorptive membranes feature high static as well as dynamic protein adsorption capacities for operating flow rates ranging from 200 to 400 L h bar per m2 and ionic strength of 20–200 mM. In a sequential desorption step by changing the pH and/or the ionic strength of the eluent, up to 90% protein recovery was obtained. Next to the separation, the mixed matrix adsorber membrane functions as a concentration medium since the protein can be concentrated up to 20‐fold in the eluent. The adsorber membranes can be reused in multiple adsorption/desorption cycles with good adsorption performances. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 564–572, 2003.
On‐line biomass monitoring of CHO perfusion culture with scanning dielectric spectroscopy
Authors: Cannizzaro Christopher , Gügerli Raphael , Marison Ian , von Stockar Urs
Published: October 2003

In this work, dielectric spectroscopy was used to monitor two CHO perfusion culture experiments (B14 and B16). The capacitance of the cell suspension was recorded every 20 minutes over an excitation frequency range of 0.2 MHz to 10.0 MHz. A phase plot of the capacitance at a low excitation frequency vs. the value at a higher frequency proved to be an accurate indicator of the major transition points of the culture, i.e., maximum cell viability, end of lactate consumption, point of zero viability. For both experiments, the capacitance signal correlated very well (R2 >0.98) with viable cell number up to concentrations of 1 × 107 cells/mL. Visual observation of the capacitance spectra indicated that changes in the capacitance relative to frequency were related to the cellular morphology. A multivariate model was developed using off‐line data that could predict the median cell diameter within a single experiment (B14) with an error of 0.34 μm (2%). Upon extension to a subsequent experiment (B16), the predicted error was 1.18 μm (9%). © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 597–610, 2003.
Purification of histidine‐tagged single‐chain Fv‐antibody fragments by metal chelate affinity precipitation using thermoresponsive copolymers
Authors: Kumar Ashok , Wahlund Per‐Olof , Kepka Cecilia , Galaev Igor Yu , Mattiasson Bo
Published: October 2003

Metal chelate affinity precipitation (MCAP) has been successfully developed as a simple purification process for proteins that have affinity for metal ions. The present lack of widespread applications for this technique as compared to immobilized metal affinity chromatography (IMAC) may be related to the scarcity of well‐characterized metal affinity macroligands (AML) and their applications to the number of different purification systems. In the present work we describe a detailed study of a new purification system using metal‐loaded thermoresponsive copolymers as AML. The copolymers of vinylimidazole (VI) with N‐isopropylacrylamide (NIPAM) were synthesized by radical polymerization with imidazole contents of 15 and 24 mol%. When loaded with Cu(II) and Ni(II) ions the copolymers selectively precipitated extracellularly expressed histidine‐tagged single‐chain Fv‐antibody fragments (His6‐scFv fragments) from the fermentation broth free from E. coli cells. Precipitation was induced by salt at mild temperatures and the bound antibody fragments were recovered by dissolving the protein‐polymer complex in EDTA buffer and subsequent reprecipitation of the polymer. His6‐scFv fragments were purified with yields of 91 and 80% and purification folds of 16 and 21 when Cu(II) and Ni(II) copolymers were used, respectively. The protein precipitation capacity of the Ni(II) copolymer showed a dependence on the VI concentration in the copolymer. The SDS‐PAGE pattern showed significant purification of the antibody fragments. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 494–503, 2003.
Primmorphs from archaeocytes‐dominant cell population of the sponge hymeniacidon perleve: improved cell proliferation and spiculogenesis
Authors: Zhang Xiaoying , Cao Xupeng , Zhang Wei , Yu Xingju , Jin Meifang
Published: October 2003

Marine sponges (Porifera) possess an extraordinary diversity of bioactive metabolites for new drug discovery and development. In vitro cultivation of sponge cells in a bioreactor system is very attractive for the sustainable production of sponge‐derived bioactive metabolites; however, it is still a challenging task. The recent establishment of sponge primmorphs, multicellular aggregates from dissociated mixed‐cell population (MCP), has been widely acknowledged to hold great promise for cultivation in vitro. Here we present a new method to establish an in vitro sponge primmorph culture from archaeocyte‐dominant cell population (ADCP) enriched by a Ficoll gradient, rather than a mixed‐cell population (MCP). Our rationale is based upon the totipotency (the ability of a cell to differentiate into other cell types) of archaeocyte cells and the different biological functions of various sponge cell types. A sponge, Hymeniacidon perleve collected from the China Yellow Sea was used as a model system for this investigation. Distinct dynamics of primmorph formation were observed while significant increases in DNA synthesis, cell proliferation (up to threefold), and cell growth (up to fourfold) were achieved. Furthermore, a time‐dependent spiculogenesis was clearly demonstrated in our longterm culture, indicating high metabolic activity of primmorphs from the ADCP. This new method represents an important step forward to advance sponge cell culture in vitro that may lead to commercial exploitation of sponge‐derived drugs. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 583–590, 2003.
Bioscrubbing of waste gas—substrate absorber to avoid instability induced by inhibition kinetics
Authors: Oliveira Teresa A. C. , Livingston Andrew G.
Published: October 2003

The stability of a continuous stirred tank bioreactor treating a gas stream containing monochlorobenzene (MCB) was studied theoretically and experimentally. A bioreactor inoculated with Pseudomonas sp. strain JS150 was submitted to successive step disturbances in the MCB load, inducing washout and system instability. With time, and subject to high MCB concentrations in the biomedium, the microorganisms appeared to adapt to high MCB load, and needed increasingly severe shocks to induce washout. To improve the bioreactor stability, the influence of an MCB‐absorber prior to the bioreactor was investigated, using silicone oil as the absorbent for MCB. A parallel was established with the first set of experiments (no absorber). Phase plane plots showed how the presence of the absorber changed the system trajectories from washout into stable pseudo‐steady states. Experimental results confirmed the benefits of the absorber in avoiding washout under high MCB loads. At periods of low loading, MCB was desorbed from the absorber. For the same loading conditions, removal efficiencies were much higher than when no absorber was present. Elimination capacities observed in the bioreactor were much higher than those previously reported for biotrickling filters treating MCB containing gas streams: 300 to 450 g m−3 h−1. Gas inlet concentrations were in the range 12 to 65 g m−3, well above the 5 g m−3 upper limit usually suggested for biological treatment of waste gases, showing that highly concentrated gas streams may be biologically treated so long as inhibitory concentrations are not reached in the bioreactor. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 552–563, 2003.
The influence of molecular variation on protein interactions
Authors: Ho Jason G. S. , Middelberg Anton P. J.
Published: October 2003

We investigated the influence of solvation forces on protein–protein interactions for two forms of lysozyme: hen egg white (HEWL) and turkey egg white (TEWL). Turkey egg white has more surface exposed hydrophobic residues than HEWL and the protein–protein interactions of TEWL are shown to be more attractive than those of HEWL, for the conditions studied. The importance of including a solvation term in the potential of mean force model, to account for molecular variation in protein surface characteristics, is highlighted. We also show that the magnitude of this solvation term can be estimated using readily available data. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 611–616, 2003.
Swirling flow implementation in a photobioreactor for batch and continuous cultures of porphyridium cruentum
Authors: Muller‐Feuga Arnaud , Pruvost Jérémy , Le Guédes Rolland , Le Déan Loic , Legentilhomme Patrick , Legrand Jack
Published: October 2003

Light is the main limiting factor in photoautotrophic‐intensive production of microorganisms, and improvement of its use is an important concern for photobioreactor design and operation. Swirling flows, which are known to improve mass and photon transfers, were applied to annular light chambers of a photobioreactor and studied by simulation and microalgal culture. Two hydrodynamic conditions were compared: axial flow generating poor radial mixing, and tangential flow generating three‐dimensional swirling motion. Batch and continuous cultures of the Rhodophyte Porphyridium cruentum were performed in a 100‐L, 1.5‐m2, fully controlled photobioreactor with eight light chambers. The inlet design of these chambers was modified to create the hydrodynamic conditions for comparison. Various intensities of swirling motion were used, characterized by the velocity factor (VF), defined as the ratio between annular chamber flow and inlet aperture sections. Experiments were performed within the range of photon flux densities (PFD) optimizing the yield of light energy transformation into living substance for the species and the temperature used. Culture kinetics with swirling flows generated by apertures of VF = 2, 4, and 9 were compared with pseudoaxial VF = 2 chosen as reference. Batch cultures with VF = 4 swirling flow showed no significant difference, whereas continuous cultures proved more discriminating. Although no significant difference was obtained for VF = 2, a 7% increase of steady‐state productivity and a 26% decrease in time required to reach this steady state were obtained with VF = 4 swirling flow. This beneficial effect of swirling flow could have accounted for increased mixing. Conversely, VF = 9 swirling flow resulted in a 9% decrease of steady‐state productivity and a 9% increase in the time required to reach this steady state, a negative effect that could have accounted for increased shear stress. CO2 bioconversion yield at steady state showed a 34% increase for VF = 4. These results suggest that swirling motion makes microalgal cultures more efficient, provided that the resulting adverse effects remain acceptable. Experimental investigation was completed by a theoretical approach in which simulation of continuous cultures of P. cruentum was based on the hydrodynamic conditions achieved in the photobioreactor. Although the results obtained with pseudoaxial flow were correctly predicted, simulations with swirling flow showed a marked enhancement of productivity not observed experimentally. The influence of side effects induced by increased mixing (particularly hydrodynamic shear stress) was considered with respect to modeling assumptions. Comparison of experimental results with theoretical simulation provided a better understanding of the mixing effect, a key factor in improving the efficiency of such bioprocesses. © 2004 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 544–551, 2003.
Minimization of carbon losses in pilot‐scale outdoor photobioreactors by model‐based predictive control
Authors: García Sánchez J. L. , Berenguel M. , Rodríguez F. , Fernández Sevilla J. M. , Brindley Alias C. , Acién Fernández F. G.
Published: October 2003

The optimization of carbon use in pilot‐scale outdoor tubular photobioreactors is investigated in this study. The behavior of a 0.20‐m3 tubular photobioreactor was studied, with and without algae, by steady‐state and pulse dynamic‐response analysis experiments. A model of the system was obtained and implemented in a programmable control unit and was used to control the reactor under normal production conditions. Results showed that, using and on–off control, the mean daily CO2 flow in the reactor was 0.86 g min−1, 19.7% of this being lost. By using a predictive control algorithm the mean daily CO2 flow was reduced to 0.74 g min−1, with losses being reduced to 15.6%. In this case, pH tracking was not adequate, especially at the beginning and end of the daylight period, because the variation in solar irradiance was not considered. Taking solar irradiance into account resulted in better performance, with mean daily CO2 flow reduced to 0.70 g min−1, and carbon losses reduced to 5.5%. pH tracking was improved and valve actuation was reduced. Improvement of pH control reduced pH gradients in the culture, which increased the photosynthesis rate and biomass productivity of the system. Biomass productivity increased from 1.28 to 1.48 g L−1 day−1 when on–off control was replaced by model‐based predictive control plus solar irradiance effect mode. Implementation of this methodology in outdoor photobioreactors can increase productivity by 15% and reduce the cost of producing biomass by >6%. Clearly, application of effective control techniques, such as model‐based predictive control (MPC), must be considered when developing these processes. © 2004 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 533–543, 2004.
Organic tissues in rotating bioreactors: fluid‐mechanical aspects, dynamic growth models, and morphological evolution
Authors: Lappa Marcello
Published: October 2003

This analysis deals with advances in tissue‐engineering models and computational methods as well as with novel results on the relative importance of “controlling forces” in the growth of organic constructs. Specifically, attention is focused on the rotary culture system, because this technique has proven to be the most practical solution for providing a suitable culture environment supporting three‐dimensional tissue assemblies. From a numerical point of view, the growing biological specimen gives rise to a moving boundary problem. A “volume‐of‐fraction” method is specifically and carefully developed according to the complex properties and mechanisms of organic tissue growth and, in particular, taking into account the sensitivity of the construct/liquid interface to the effect of the fluid‐dynamic shear stress (it induces changes in tissue metabolism and function that elicit a physiological response from the biological cells). The present study uses available data to introduce a set of growth models. The surface conditions are coupled to the transfer of mass and momentum at the specimen/culture‐medium interface and lead to the introduction of a group of differential equations for the nutrient concentration around the sample and for the evolution of tissue mass displacement. The models are then used to show how the proposed surface kinetic laws can predict (through sophisticated numerical simulations) many of the known characteristics of biological tissues grown using rotating‐wall perfused vessel bioreactors. This procedure provides a validation of the models and associated numerical method and also gives insight into the mechanisms of the phenomena. The interplay between the increasing size of the tissue and the structure of the convective field is investigated. It is shown that this interaction is essential in determining the time evolution of the tissue shape. The size of the growing specimen plays a critical role with regard to the intensity of convection and the related shear stresses. Convective effects, in turn, are found to impact growth rates, tissue size, and morphology, as well as the mechanisms driving growth. The method exhibits novel capabilities to predict and elucidate experimental observations and to identify cause‐and‐effect relationships. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 518–532, 2003.
Efficient anaerobic whole cell stereoselective bioreduction with recombinant saccharomyces cerevisiae
Authors: Katz Michael , Frejd Torbjörn , Hahn‐Hägerdal Bärbel , Gorwa‐Grauslund Marie F.
Published: October 2003

In this study we investigate the NADPH‐dependent stereoselective reduction of the bicyclic diketone bicyclo[2.2.2]octane‐2,6‐dione (BCO2,6D) to the chiral ketoalcohol (1R,4S,6S)‐6‐hydroxybicyclo[2.2.2]octane‐2‐one (BCO2one6ol). Our aim was to develop a whole cell batch process for reduction of carbonyl substrates with (i) a high cosubstrate yield (formed product/consumed cosubstrate) and (ii) a high conversion rate under anaerobic conditions with Saccharomyces cerevisiae as biocatalyst and glucose as cosubstrate. Five open reading frames (ORFs), YMR226c, YDR368w, YOR120w, YGL157w, and YGL039w, encoding reductases involved in the conversion of BCO2,6D were identified using cell‐free extract from strains belonging to the ExClone collection (yeast ORF expression clones; ResGen, Invitrogen Corp., UK). We report the one‐step purification and characterization of three major BCO2,6D reductases, YMR226cp, YDR368wp (YPR1p), and YOR120wp (GCY1p). The reductases were overexpressed under a strong constitutive promoter and the impact on cosubstrate yield, conversion time, glucose consumption rate, and reduction rate was investigated when reductases were overexpressed either alone or in combination with low phosphoglucose isomerase activity (encoded by YBR196c). Combining overexpression of BCO2,6D reductase with reduced glycolytic rate (low phosphoglucose isomerase activity) offers a fast whole cell stereoselective bioreduction system useful for facilitated anaerobic batch conversions. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 573–582, 2003.
Use of complex DNA and antibody microarrays as tools in functional analyses
Authors: Bauer Andrea , Beckmann Boris , Busold Christian , Brandt Ole , Kusnezow Wlad , Pullat Janne , Aign Verena , Fellenberg Kurt , Fleischer Robert , Jacob Anette , Frohme Marcus , Hoheisel Jörg D.
Published: October 2003

While the deciphering of basic sequence information on a genomic scale is yielding complete genomic sequences in ever‐shorter intervals, experimental procedures for elucidating the cellular effects and consequences of the DNA‐encoded information become critical for further analyses. In recent years, DNA microarray technology has emerged as a prime candidate for the performance of many such functional assays. Technically, array technology has come a long way since its conception some 15 years ago, initially designed as a means for large‐scale mapping and sequencing. The basic arrangement, however, could be adapted readily to serve eventually as an analytical tool in a large variety of applications. On their own or in combination with other methods, microarrays open up many new avenues of functional analysis. Copyright © 2003 John Wiley & Sons, Ltd.
Transient expression of doublecortin during adult neurogenesis
Authors: Brown Jason P. , Couillard‐Després Sébastien , Cooper‐Kuhn Christiana M. , Winkler Jürgen , Aigner Ludwig , Kuhn H. Georg
Published: October 2003

During development of the central nervous system, expression of the microtubule binding protein doublecortin (DCX) is associated with migration of neuroblasts. In addition to this developmental role, expression of DCX remains high within certain areas of the adult mammalian brain. These areas, mainly the dentate gyrus and the lateral ventricle wall in conjunction with the rostral migratory stream and olfactory bulb, retain the capacity to generate new neurons into adulthood. Adult neurogenesis is typically detected by incorporation of bromodeoxyuridine (BrdU) into dividing cells and colabeling of BrdU‐positive cells with markers for mature neurons. To elucidate whether DCX could act as an alternative indicator for adult neurogenesis, we investigated the temporal expression pattern of DCX in neurogenic regions of the adult brain. Analysis of newly generated cells showed that DCX is transiently expressed in proliferating progenitor cells and newly generated neuroblasts. As the newly generated cells began expressing mature neuronal markers, DCX immunoreactivity decreased sharply below the level of detection and remained undetectable thereafter. The transient expression pattern of DCX in neuronal committed progenitor cells/neuroblasts indicates that DCX could be developed into a suitable marker for adult neurogenesis and may provide an alternative to BrdU labeling. This assumption is further supported by our observation that the number of DCX‐expressing cells in the dentate gyrus was decreased with age according to the reduction of neurogenesis in the aging dentate gyrus previously reported. J. Comp. Neurol. 467:1–10, 2003. © 2003 Wiley‐Liss, Inc.
Green fluorescent protein expression and colocalization with calretinin, parvalbumin, and somatostatin in the GAD67‐GFP knock‐in mouse
Authors: Tamamaki Nobuaki , Yanagawa Yuchio , Tomioka Ryohei , Miyazaki Jun‐Ichi , Obata Kunihiko , Kaneko Takeshi
Published: October 2003

γ‐aminobutyric acid (GABA)ergic neurons in the central nervous system regulate the activity of other neurons and play a crucial role in information processing. To assist an advance in the research of GABAergic neurons, here we produced two lines of glutamic acid decarboxylase–green fluorescence protein (GAD67‐GFP) knock‐in mouse. The distribution pattern of GFP‐positive somata was the same as that of the GAD67 in situ hybridization signal in the central nervous system. We encountered neither any apparent ectopic GFP expression in GAD67‐negative cells nor any apparent lack of GFP expression in GAD67‐positive neurons in the two GAD67‐GFP knock‐in mouse lines. The timing of GFP expression also paralleled that of GAD67 expression. Hence, we constructed a map of GFP distribution in the knock‐in mouse brain. Moreover, we used the knock‐in mice to investigate the colocalization of GFP with NeuN, calretinin (CR), parvalbumin (PV), and somatostatin (SS) in the frontal motor cortex. The proportion of GFP‐positive cells among NeuN‐positive cells (neocortical neurons) was approximately 19.5%. All the CR‐, PV‐, and SS‐positive cells appeared positive for GFP. The CR‐, PV, and SS‐positive cells emitted GFP fluorescence at various intensities characteristics to them. The proportions of CR‐, PV‐, and SS‐positive cells among GFP‐positive cells were 13.9%, 40.1%, and 23.4%, respectively. Thus, the three subtypes of GABAergic neurons accounted for 77.4% of the GFP‐positive cells. They accounted for 6.5% in layer I. In accord with unidentified GFP‐positive cells, many medium‐sized spherical somata emitting intense GFP fluorescence were observed in layer I. J. Comp. Neurol. 467:60–79, 2003. © 2003 Wiley‐Liss, Inc.
Synapse replacement in the striatum of the adult rat following unilateral cortex ablation
Authors: McNeill Thomas H. , Brown Sally A. , Hogg Elizabeth , Cheng Heng‐Wei , Meshul Charles K.
Published: October 2003

Defining the selective pattern of synapse replacement that occurs in different areas of the damaged brain is essential for predicting the limits of functional compensation that can be achieved after various types of brain injury. Here we describe the time course of dendritic reorganization, spine loss and recovery, and synapse replacement in the striatum following a unilateral cortex ablation. We found that the time course for the transient loss and recovery of dendritic spines on medium spiny I (MSI) neurons, the primary postsynaptic target for corticostriatal axons, paralleled the time course for the removal of degenerating axon terminals from the neuropil and the formation of new synapses on MSI neurons. Reinnervation of the deafferented striatum occurred chiefly by axon terminals that formed asymmetric synapses with dendritic spines of MSI neurons, and the mean density of asymmetric synapses recovered to 86% of the sham‐operated rat value by 30 days postlesion. In addition, the synaptic circuitry of the reconstructed striatum was characterized by an increase in the number of multiple synaptic boutons (MSBs), i.e., presynaptic axon terminals that make contact with more than one dendritic spine. Whether the postsynaptic contacts of MSBs are formed with the dendritic spines of the same or a different parent dendrite in the striatum is unknown. Nevertheless, these data suggest that the formation of MSBs is an essential part of the compensatory response to the loss of input from the ipsilateral cortex following the aspiration lesion and may serve to modulate activity‐dependent adaptive changes in the reconstructed striatum that can lead to functional recovery. J. Comp. Neurol. 467:32–43, 2003. © 2003 Wiley‐Liss, Inc.
Brain‐derived neurotrophic factor regulates expression of vasoactive intestinal polypeptide in retinal amacrine cells
Authors: Cellerino Alessandro , Arango‐González Blanca , Pinzón‐Duarte Germán , Kohler Konrad
Published: October 2003

Brain‐derived neurotrophic‐factor (BDNF) is expressed in the retina and controls the development of subtypes of amacrine cells. In the present study we investigated the effects of BDNF on amacrine cells expressing vasoactive intestinal polypeptide (VIP). Rats received three intraocular injections of BDNF on postnatal days (P) 16, 18, and 20. The animals were sacrificed on P22, P40, P60, P80, and P120, and VIP expression in their retinas was detected by immunohistochemistry (P22, P40) and by radioimmunoassay (RIA; P22, P40, P60, P80, P120) to assess the time course of BDNF effects on VIP. A significant increase in the density of VIP‐positive amacrine cells was detected in BDNF‐treated retinas, and VIP concentration was up‐regulated by 150% both at P22 and at P40 with respect to untreated controls. VIP concentration then slowly declined in the treated retinas over a period of 3 months; however, a statistically significant increase of 50% was still detectable on P120. The impact of endogenous BDNF on the regulation of VIP expression in the retina was analyzed in mice homozygous for a targeted deletion of the BDNF gene locus (bdnf−/−). VIP immunohistochemistry revealed a marked reduction of VIP‐positive amacrine cells and of VIP‐immunopositive processes in the inner plexiform layer of the BDNF knockout mice. Mice lacking BDNF expressed only 5% of the VIP protein in their retinas compared with the retinas of wild‐type mice as measured by RIA. Our data show that BDNF is a major regulator of VIP expression in retinal amacrine cells and exerts long‐lasting effects on VIP content. J. Comp. Neurol. 467:97–104, 2003. © 2003 Wiley‐Liss, Inc.
Organization of somatosensory cortex in the laboratory rat (Rattus norvegicus): Evidence for two lateral areas joined at the representation of the teeth
Authors: Remple Michael S. , Henry Erin C. , Catania Kenneth C.
Published: October 2003

Lateral somatosensory areas have not been explored in detail in rats, and theories on the organization of this region are based largely on anatomical tracing experiments. We investigated the topography of this region by using microelectrode recordings, which were related to flattened cortical sections processed for cytochrome oxidase (CO). Two lateral somatosensory areas were identified, each containing a complete representation of the body. A larger, more medial representation formed a mirror image of S1 along the rostrocaudal axis of the head region corresponding to the previously identified secondary somatosensory area (S2). A smaller, more lateral representation formed a mirror image of S2 along the rostrocaudal axis of the forelimb and hindlimb regions and likely corresponds to the parietal ventral area (PV) identified in other mammals. We also investigated the representation of the dentition and identified regions of cortex responsive to tooth stimulation. The lower incisor representation was rostral to the lower lip region of S1, and the upper incisor representation was lateral to the buccal pad region of S1. The upper and lower incisors flanked the tongue representation. An additional large region of far lateral cortex responded to both incisors. Finally, five CO‐dense modules were consistently identified rostral and lateral to the S1 face representation, which we refer to as OM1, OM2, OM3, FM, and HM. These modules closely correspond to the physiologically identified areas representing the lower incisor (OM1) and tongue (OM2) regions of S1 and the mixed tooth (OM3), forelimb (FM1), and hindlimb (HM) representations of S2 and PV. J. Comp. Neurol. 467:105–118, 2003. © 2003 Wiley‐Liss, Inc.
Cell surface carbohydrates and glomerular targeting of olfactory sensory neuron axons in the mouse
Authors: Lipscomb Brian W. , Treloar Helen B. , Klenoff Jason , Greer Charles A.
Published: October 2003

Cell surface carbohydrates have been implicated in axon guidance and targeting throughout the nervous system. We have begun to test the hypothesis that, in the olfactory system, a differential distribution of cell surface carbohydrates may influence olfactory sensory neuron (OSN) axon targeting. Specifically, we have examined the spatial distribution of two different plant lectins, Ulex europaeus agglutinin (UEA) and Dolichos biflorus agglutinin (DBA), to determine whether they exhibit differential and reproducible projections onto the main olfactory bulb. Each lectin exhibited a unique spatial domain of glomerular labeling that was consistent across animals. UEA labeling was strongest in the ventral aspect of the olfactory bulb; DBA labeling was strongest in the dorsal aspect of the olfactory bulb. Some evidence for colocalization was present where these two borders intersected. Large areas of the glomerular layer were not labeled by either lectin. To determine whether patterns of lectin labeling were reproducible at the level of individual glomeruli, UEA labeling was assessed relative to M72‐IRES‐taulacZ‐ and P2‐IRES‐taulacZ‐labeled axons. Although glomeruli neighboring these two identified glomeruli were consistently labeled with UEA, none of the lacZ positive axons was lectin labeled. Labeling of vomeronasal sensory neuron axons in the accessory olfactory bulb was more uniform for the two lectins. These data are the first to show a differential distribution of UEA vs. DBA labeling in the main olfactory bulb and are consistent with the hypothesis that a differential distribution of cell surface carbohydrates, a glycocode, may contribute to the targeting of OSN axons. J. Comp. Neurol. 467:22–31, 2003. © 2003 Wiley‐Liss, Inc.
Development of a sexually dimorphic neuromuscular system in male rats after spinal transection: Morphologic changes and implications for estrogen sites of action
Authors: Hebbeler Sara L. , Sengelaub Dale R.
Published: October 2003

The lumbar spinal cord of rats contains the sexually dimorphic, steroid‐sensitive spinal nucleus of the bulbocavernosus (SNB). In male rats, SNB motoneurons exhibit a biphasic pattern of dendritic growth, having an initial period of exuberant growth followed by a period of retraction to mature lengths by 7 weeks of age. This growth is steroid dependent: dendrites fail to grow after castration, but growth is supported in castrates treated with estradiol. In this experiment, we examined whether supraspinal afferent input by means of descending spinal tracts to the SNB was involved in the normal postnatal development of SNB motoneurons, and whether the effect of estradiol on SNB dendritic growth could be explained by an indirect action of estradiol on supraspinal afferents. Motoneuron morphology was assessed in normal males, early‐ or late‐postnatally transected males, castrated males left untreated or treated with estradiol, and transected castrates treated with estradiol. SNB motoneurons were retrogradely labeled with cholera toxin–horseradish peroxidase during both the growth and retraction phases of dendritic development and reconstructed in three dimensions. The removal of supraspinal afferents resulted in extremely local effects within the developing SNB arbor, as well as transient alterations in somal growth. Furthermore, spinal transection did not block the trophic effect of estradiol on supporting SNB dendritic growth, indicating that estrogens do not act by means of supraspinal input to support SNB motoneuron development. J. Comp. Neurol. 467:80–96, 2003. © 2003 Wiley‐Liss, Inc.
Nicotinic acetylcholine receptor distribution in relation to spinal neurotransmission pathways
Authors: Khan Imran , Osaka Hitoshi , Stanislaus Shanaka , Calvo Rosa M. , Deerinck Tom , Yaksh Tony L. , Taylor Palmer
Published: October 2003

Neuronal nicotinic receptors (nAChR) are pentameric assemblies of subunits of a gene family where specified combinations of α and β subunits form functional receptors. To extend our understanding of the role of spinal nAChR in the processing of sensory stimuli and regulation of autonomic and motor responses, we initiated investigations to localize nAChR subunit expression within discrete spinal regions and cell types. High‐affinity epibatidine binding was present in the superficial dorsal and ventral horns, the mediolateral and central canal regions. RT‐PCR identified transcripts for α3, α4, α5, β2, and β4 in both spinal cord parenchyma and dorsal root ganglia (DRG). Our affinity‐purified antibodies against α3, α4, α5, β2, and β4 subunits identified specific protein bands of appropriate molecular mass (preadsorbed with the respective antigens) in specific tissues and cells that express nicotinic receptors, including the spinal cord and DRG neurons. Having established the absence of crossreactivity with related subunits, specific fluorescence labeling of nerve terminals and cell bodies was achieved and correlated with the distribution of defined marker proteins and nicotinic receptor binding sites determined autoradiographically. Our findings indicate that α3, α4, α5, β2, and β4 subunits are all expressed on primary afferents (IB4‐positive terminals) in the spinal cord. The predominant presynaptic (synaptophysin colocalization) labeling is in the superficial layer of the dorsal horn. These receptor subunits, except for β4, are also present in postsynaptic autonomic (anti‐bNOS‐positive) and somatic motor neurons (anti‐VAChT‐positive). The α3, α5, and β2 subunits showed additional staining in glial (anti‐GFAP‐positive) cells. These studies reveal a dense and distinguishable distribution of nAChR subunits in the spinal cord and point toward future therapeutic targeting for specific spinal actions. J. Comp. Neurol. 467:44–59, 2003. © 2003 Wiley‐Liss, Inc.
Spatial representation of odorant structure in the moth antennal lobe: A study of structure–response relationships at low doses
Authors: Meijerink Jocelijn , Carlsson Mikael A. , Hansson Bill S.
Published: October 2003

How odorant structure and concentration are spatially represented within the primary olfactory integration center, the antennal lobe (AL) or olfactory bulb (OB) in invertebrates and vertebrates, respectively, is currently a topic of high interest. Here, we show the spatial representation of odorant structure in the antennal lobe of the moth Spodoptera littoralis by imaging calcium activity evoked by straight chain aliphatic alcohols and aldehydes at low doses. Activity patterns of a given odor were most similar to compounds with the same functional group, differing in chain length by only one carbon atom. A chain length dependency was present as the most activated glomerulus in the lobe shifted from a medial to a lateral position with increasing chain length of the molecule. Statistical analysis revealed that in both classes of chemicals the chain length of the molecule was represented in a similar way. No topographically fixed domains were observed for any of the classes. However, activity patterns evoked by lower chain length molecules were spatially more distinct than patterns evoked by higher chain length molecules. The number of activated glomeruli for both classes of chemicals increased with increasing chain length to reach a maximum at eight or nine C atoms followed by a decrease as the chain length further increased. J. Comp. Neurol. 467:11–21, 2003. © 2003 Wiley‐Liss, Inc.
Expression of constitutively active p21H‐rasval12 in postmitotic pyramidal neurons results in increased dendritic size and complexity
Authors: Alpár Alán , Palm Kirstin , Schierwagen Andreas , Arendt Thomas , Gärtner Ulrich
Published: October 2003

The small G protein p21Ras is a critical molecular switch for relaying neurotrophic actions and is essential for normal functioning and plasticity of the nervous system. In this study, the morphogenetic effects of p21Ras were investigated on neurons in vivo. Morphological changes of layers II/III and Vb commissural pyramidal neurons of the primary somatosensory cortex were analyzed in transgenic mice expressing permanently active p21H‐RasVal12 in postmitotic neurons. Pyramidal cells were retrogradely labelled with biotinylated dextran amine and subsequently traced using Neurolucida. Compared with wild‐type mice, transgenic animals showed a significant increase in the surface area and volume of basal dendrites on the proximal and intermediate segments in layers II/III and on further distal segments in layer V. In addition, the surface area and volume of the trunk and of the proximal segments of oblique branches of apical dendrites were enlarged in both layers. Sholl analyses of basal and apical dendrites showed a significant increase in dendritic complexity of layer V neurons. A positive correlation was observed between the size of the basal dendrite and the neuronal soma size in the transgenic population, indicating that growth‐promoting effects of p21H‐RasVal12 affect both cellular compartments in parallel. However, the dendritic surface correlated with the number of tips and dendritic stem diameter in both wild‐type and transgenic populations, demonstrating that these relations represent rather conservative design principles in dendritic morphology. The data presented here suggest an important role of p21Ras‐dependent signaling in the final differentiation and maintenance of dendritic morphology. J. Comp. Neurol. 467:119–133, 2003. © 2003 Wiley‐Liss, Inc.
Coupling of mapped wave infinite elements and plane wave basis finite elements for the Helmholtz equation in exterior domains
Authors: Sugimoto Rie , Bettess Peter
Published: October 2003

The theory for coupling of mapped wave infinite elements and special wave finite elements for the solution of the Helmholtz equation in unbounded domains is presented. Mapped wave infinite elements can be applied to boundaries of arbitrary shape for exterior wave problems without truncation of the domain. Special wave finite elements allow an element to contain many wavelengths rather than having many finite elements per wavelength like conventional finite elements. Both types of elements include trigonometric functions to describe wave behaviour in their shape functions. However the wave directions between nodes on the finite element/infinite element interface can be incompatible. This is because the directions are normally globally constant within a special finite element but are usually radial from the ‘pole’ within a mapped wave infinite element. Therefore forcing the waves associated with nodes on the interface to be strictly radial is necessary to eliminate this internode incompatibility. The coupling of these elements was tested for a Hankel source problem and plane wave scattering by a cylinder and good accuracy was achieved. This paper deals with unconjugated infinite elements and is restricted to two‐dimensional problems. Copyright © 2003 John Wiley & Sons, Ltd.
Interior point optimization and limit analysis: an application
Authors: Pastor Joseph , Thai The‐Hung , Francescato Pascal
Published: October 2003

The well‐known problem of the height limit of a Tresca or von Mises vertical slope of height h, subjected to the action of gravity stems naturally from Limit Analysis theory under the plane strain condition. Although the exact solution to this problem remains unknown, this paper aims to give new precise bounds using both the static and kinematic approaches and an Interior Point optimizer code. The constituent material is a homogeneous isotropic soil of weight per unit volume γ. It obeys the Tresca or von Mises criterion characterized by C cohesion. We show that the loading parameter to be optimized, γh/C, is found to be between 3.767 and 3.782, and finally, using a recent result of Lyamin and Sloan (Int. J. Numer. Meth. Engng. 2002; 55: 573), between 3.772 and 3.782. The proposed methods, combined with an Interior Point optimization code, prove that linearizing the problem remains efficient, and both rigorous and global: this point is the main objective of the present paper. Copyright © 2003 John Wiley & Sons, Ltd.
A novel approach to the convexity control of interpolant curves
Authors: Duan Qi , Wang Liqiu , Twizell E. H.
Published: October 2003

A method is presented for controlling the convexity of interpolant curves based on a rational cubic interpolating function with quadratic denominator. The key idea is that the uniqueness of the interpolating function for the given data is replaced by the uniqueness of the interpolating function for the given data and the parameters, so that for the given data the shape of the interpolating curve can be modified by selecting suitable parameters. Necessary and sufficient conditions are given for adjusting the convexity of the interpolating curve for given data. Examples are given and the optimal error estimation is given. Copyright © 2003 John Wiley & Sons, Ltd.
Thermal avalanche for blowup solutions of semilinear heat equations
Authors: Quirós Fernando , Rossi Julio D. , Vázquez Juan Luis
Published: October 2003

We consider the semilinear heat equation ut = Δu + up both in ℝN and in a bounded domain with homogeneous Dirichlet boundary conditions, with 1 < p < ps where ps is the Sobolev exponent. This problem has solutions with finite‐time blowup; that is, for large enough initial data there exists T < ∞ such that u is a classical solution for 0 < t < T, while it becomes unbounded as t ↗ T. In order to understand the situation for t > T, we consider a natural approximation by reaction problems with global solution and pass to the limit. As is well‐known, the limit solution undergoes complete blowup: after it blows up at t = T, the continuation is identically infinite for all t > T.

We perform here a deeper analysis of how complete blowup occurs. Actually, the singularity set of a solution that blows up as t ↗ T propagates instantaneously at time t = T to cover the whole space, producing a catastrophic discontinuity between t = T− and t = T+. This is called the “avalanche.” We describe its formation as a layer appearing in the limit of the natural approximate problems. After a suitable scaling, the initial structure of the layer is given by the solution of a limit problem, described by a simple ordinary differential equation. As t proceeds past T, the solutions of the approximate problems have a traveling wave behavior with a speed that we compute. The situation in the inner region depends on the type of approximation: a conical pattern is formed with time when we approximate the power up by a flat truncation at level n, while for tangent truncations we get an exponential increase in time and a diffusive spatial pattern. © 2003 Wiley Periodicals, Inc.
Local minimizers with vortices to the Ginzburg‐Landau system in three dimensions
Authors: Montero J. Alberto , Sternberg Peter , Ziemer William P.
Published: October 2003

We construct local minimizers to the Ginzburg‐Landau energy in certain three‐dimensional domains based on the asymptotic connection between the energy and the total length of vortices using the theory of weak Jacobians. Whenever there exists a collection of locally minimal line segments spanning the domain, we can find local minimizers with arbitrarily assigned degrees with respect to each segment. © 2003 Wiley Periodicals, Inc.
Pseudoholomorphic strips in symplectizations II: Fredholm theory and transversality
Authors: Abbas Casim
Published: October 2003

This paper is part of a larger program, the investigation of the chord problem in three dimensional contact geometry. The main tool will be pseudoholomorphic strips in the symplectisation of a three dimensional contact manifold with two totally real submanifolds L0, L1 as boundary conditions. The submanifolds L0 and L1 do not intersect transversally. In this paper we will develop a nonlinear Fredholm theory that guarantees the existence of a family of embedded pseudoholomorphic strips near a given one with suitable properties. © 2003 Wiley Periodicals, Inc.