bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of Gephyrin Cluster Size and Inhibitory Synaptic Currents on Renshaw Cells by Motor Axon Excitatory Inputs
Authors: Gonzalez-Forero David , Pastor Angel M. , Geiman Eric J. , Benítez-Temiño Beatriz , Alvarez Francisco J.
Published: January 2005

Renshaw cells receive a high density of inhibitory synapses characterized by large postsynaptic gephyrin clusters and mixed glycinergic/GABAergic inhibitory currents with large peak amplitudes and long decays. These properties appear adapted to increase inhibitory efficacy over Renshaw cells and mature postnatally by mechanisms that are unknown. We tested the hypothesis that heterosynaptic influences from excitatory motor axon inputs modulate the development of inhibitory synapses on Renshaw cells. Thus, tetanus (TeNT) and botulinum neurotoxin A (BoNT-A) were injected intramuscularly at postnatal day 5 (P5) to, respectively, elevate or reduce motor axon firing activity for ∼2 weeks. After TeNT injections, the average gephyrin cluster areas on Renshaw cells increased by 18.4% at P15 and 28.4% at P20 and decreased after BoNT-A injections by 17.7% at P15 and 19.9% at P20. The average size differences resulted from changes in the proportions of small and large gephyrin clusters. Whole-cell recordings in P9-P15 Renshaw cells after P5 TeNT injections showed increases in the peak amplitude of glycinergic miniature postsynaptic currents (mPSCs) and the fast component of mixed (glycinergic/GABAergic) mPSCs compared with controls (60.9% and 78.9%, respectively). GABAergic mPSCs increased in peak amplitude to a smaller extent (45.8%). However, because of the comparatively longer decays of synaptic GABAergic currents, total current transfer changes after TeNT were similar for synaptic glycine and GABAAreceptors (56 vs 48.9% increases, respectively). We concluded that motor axon excitatory synaptic activity modulates the development of inhibitory synapse properties on Renshaw cells, influencing recruitment of postsynaptic gephyrin and glycine receptors and, to lesser extent, GABAAreceptors.
High-Threshold K+Current Increases Gain by Offsetting a Frequency-Dependent Increase in Low-Threshold K+Current
Authors: Fernandez Fernando R. , Mehaffey W. Hamish , Molineux Michael L. , Turner Ray W.
Published: January 2005

High-frequency firing neurons are found in numerous central systems, including the auditory brainstem, thalamus, hippocampus, and neocortex. The kinetics of high-threshold K+currents (IKHT) from the Kv3 subfamily has led to the proposal that these channels offset cumulative Na+current inactivation and stabilize tonic high-frequency firing. However, all high-frequency firing neurons, examined to date, also express low-threshold K+currents (IKLT) that have slower kinetics and play an important role in setting the subthreshold and filtering properties of the neuron. IKLThas also been shown to dampen excitability and is therefore likely to oppose high-frequency firing. In this study, we examined the role of IKHTin pyramidal cells of the electrosensory lobe of weakly electric fish, which are characterized by high-frequency firing, a very wide frequency range, and high levels of IKHT. In particular, we examined the mechanisms that allow IKHTto set the gain of theF-Irelationship by interacting with another low-threshold K+current. We found that IKHTincreases the gain of theF-Irelationship and influences spike waveform almost exclusively in the high-frequency firing range. The frequency dependence arises from IKHTinfluencing both the IKLTand Na+currents. IKHTthus plays a significant role in stabilizing high-frequency firing by preventing a steady-state accumulation of IKLTthat is as important as preventing Na+current inactivation.
The Micromolar Zinc-Binding Domain on the NMDA Receptor Subunit NR2B
Authors: Rachline Julie , Perin-Dureau Florent , Le Goff Anne , Neyton Jacques , Paoletti Pierre
Published: January 2005

Eukaryotic ionotropic glutamate receptor subunits possess a large N-terminal domain (NTD) distinct from the neighboring agonist-binding domain. In NMDA receptors, the NTDs of NR2A and NR2B form modulatory domains binding allosteric inhibitors. Despite a high sequence homology, these two domains have been shown to bind two ligands of strikingly different chemical nature. Whereas the NTD of NR2A binds zinc with high (nanomolar) affinity, the NTD of NR2B binds the synthetic neuroprotectant ifenprodil and its derivatives. Using both NTD-mutated/deleted receptors and isolated NTDs, we now show that the NTD of NR2B, in contrast to NR2C and NR2D, also binds zinc, but with a lower affinity. Furthermore, we present evidence that zinc and ifenprodil compete for an overlapping binding site. This modulatory binding site accounts for the submicromolar zinc inhibition of NR1/NR2B receptors. Given that zinc is accumulated and released at many glutamatergic synapses in the CNS, these findings suggest that zinc is the endogenous ligand of the NTD of both NR2A and NR2B, the two major NR2 subunits. Thus, NMDA receptors contain zinc sensors capable of detecting extracellular zinc over a wide concentration range depending on their NR2 subunit composition. The coexistence of subunit-specific zinc-binding sites of high (nanomolar) and low (micromolar) affinity on NMDA receptors raises the possibility that zinc exerts both a tonic and a phasic control of membrane excitability.
Relationship of Brain-Derived Neurotrophic Factor and Its Receptor TrkB to Altered Inhibitory Prefrontal Circuitry in Schizophrenia
Authors: Hashimoto Takanori , Bergen Sarah E. , Nguyen Quyen L. , Xu Baoji , Monteggia Lisa M. , Pierri Joseph N. , Sun Zhuoxin , Sampson Allan R. , Lewis David A.
Published: January 2005

Dysfunction of inhibitory neurons in the prefrontal cortex (PFC), represented by decreased expression of GABA-related genes such as the 67 kDa isoform of glutamate decarboxylase (GAD67) and parvalbumin (PV), appears to contribute to cognitive deficits in subjects with schizophrenia. We investigated the involvement of signaling mediated by brain-derived neurotrophic factor (BDNF) and its receptor tyrosine kinase TrkB in producing the altered GABA-related gene expression in schizophrenia. In 15 pairs of subjects with schizophrenia and matched control subjects, both BDNF and TrkB mRNA levels, as assessed byin situhybridization, were significantly decreased in the PFC of the subjects with schizophrenia, whereas the levels of mRNA encoding the receptor tyrosine kinase for neurotrophin-3, TrkC, were unchanged. In this cohort, within-pair changes in TrkB mRNA levels were significantly correlated with those in both GAD67and PV mRNA levels. Decreased BDNF, TrkB, and GAD67mRNA levels were replicated in a second cohort of 12 subject pairs. In the combined cohorts, the correlation between within-pair changes in TrkB and GAD67mRNA levels was significantly stronger than the correlation between the changes in BDNF and GAD67mRNA levels. Neither BDNF nor TrkB mRNA levels were changed in the PFC of monkeys after a long-term exposure to haloperidol. Genetically introduced decreases in TrkB expression, but not in BDNF expression, also resulted in decreased GAD67and PV mRNA levels in the PFC of adult mice; in addition, the cellular pattern of altered GAD67mRNA expression paralleled that present in schizophrenia. Decreased TrkB signaling appears to underlie the dysfunction of inhibitory neurons in the PFC of subjects with schizophrenia.
Specific Modulation of Na+Channels in Hippocampal Neurons by Protein Kinase Cϵ
Authors: Chen Yuan , Cantrell Angela R. , Messing Robert O. , Scheuer Todd , Catterall William A.
Published: January 2005

Acetylcholine binding to muscarinic acetylcholine receptors activates G-proteins, phospholipase C, and protein kinase C (PKC), which phosphorylates brain Na+channels and reduces peak Na+current in hippocampal neurons. Because multiple PKC isozymes with different regulatory properties are expressed in hippocampal neurons, we investigated which ones are responsible for mediating this effect. The diacylglycerol analog oleoylacetylglycerol (OAG) reduced the amplitude of Na+current in dissociated mouse hippocampal neurons by 28.5 ± 5.3% (p< 0.01). The reduction of peak Na+current was similar with Ca2+-free internal solution and in 92 nminternal Ca2+, suggesting that calcium-dependent, conventional PKC isozymes were unlikely to mediate this response. Gö6976, which inhibits conventional PKC isozymes, reduced the effect of PKC activators only slightly, whereas rottlerin, which inhibits PKCδ preferentially at 5 μm, had no effect. Ro-31-8425 (20 nm), which inhibits conventional PKC isozymes, did not reduce the response to OAG. However, higher concentrations of Ro-31-8425 (100 nmor 1 μm) that inhibit novel PKC isozymes effectively blocked OAG inhibition of Na+current. Inclusion of a selective PKCϵ-anchoring inhibitor peptide (PKCϵ-I) in the recording pipette prevented the reduction of peak Na+current by OAG, whereas an anchoring inhibitor peptide specific for PKCβ and an inactive scrambled PKCϵ-I peptide had no effect. In addition, OAG had no effect on Na+current in hippocampal neurons from PKCϵ null mice. Overall, our data from four experimental approaches indicate that anchored PKCϵ is the isozyme responsible for PKC-mediated reduction of peak Na+currents in mouse hippocampal neurons.
L1-Mediated Branching Is Regulated by Two Ezrin-Radixin-Moesin (ERM)-Binding Sites, the RSLE Region and a Novel Juxtamembrane ERM-Binding Region
Authors: Cheng Ling , Itoh Kouichi , Lemmon Vance
Published: January 2005

We investigated how the neural cell adhesion molecule L1 mediates neurite outgrowth through L1-L1 homophilic interactions. Wild-type L1 and L1 with mutations in the cytoplasmic domain (CD) were introduced into L1 knock-out neurons, and transfected neurons were grown on an L1 substrate. Neurite length and branching were compared between wild-type L1 and L1CD mutations. Surprisingly, the L1CD is not required for L1-mediated neurite outgrowth but plays a critical role in neurite branching, through both the juxtamembrane region and the RSLE region. We demonstrate that both regions serve as ezrin-moesin-radixin-binding sites. A truncation mutant that deletes 110 of 114 amino acids of the L1CD still supports neurite outgrowth on an L1 substrate, suggesting that a coreceptor binds to L1 incisand mediates neurite outgrowth and that L1-ankyrin interactions are not essential for neurite initiation or outgrowth. These data are consistent with a model in which L1 can influence L1-mediated neurite outgrowth and branching through both the L1CD and a coreceptor.
Circadian Rhythm Generation and Entrainment in Astrocytes
Authors: Prolo Laura M. , Takahashi Joseph S. , Herzog Erik D.
Published: January 2005

In mammals, the master circadian pacemaker is considered the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN consists of a heterogeneous population of neurons and relatively understudied glia. We investigated whether glia, like neurons, rhythmically express circadian genes. We generated pure cultures of cortical astrocytes fromPeriod2::luciferase(Per2::luc) knock-in mice andPeriod1::luciferase(Per1::luc) transgenic rats and recorded bioluminescence as a real-time reporter of gene activity. We found that ratPer1::lucand mousePer2::lucastroglia express circadian rhythms with a genetically determined period. These rhythms damped out after several days but were reinitiated by a variety of treatments, including a full volume exchange of the medium. If cultures were treated before damping out, the phase ofPer1::lucrhythmicity was shifted, depending on the time of the pulse relative to the peak ofPer1expression. Glial rhythms entrained to daily 1.5°C temperature cycles and were significantly sustained when cocultured with explants of the adult SCN but not with cortical explants. Thus, multiple signals, including a diffusible factor(s) from the SCN, are sufficient to either entrain or restart circadian oscillations in cortical glia.
Electrical Synapses between Dopaminergic Neurons of the Substantia Nigra Pars Compacta
Authors: Vandecasteele Marie , Glowinski Jacques , Venance Laurent
Published: January 2005

Spatiotemporal properties of dopamine release play a major role both in striatal and nigral physiology because dopamine is released from nerve terminals and dendrites of nigrostriatal dopaminergic (DA) neurons. Pioneering work revealed gap junctional communication (assessed by dye-coupling experiments) between DA cells in the substantia nigra pars compacta (SNc). However, direct evidence of functional electrical synapses between DA neurons is still lacking. In this study, gap junctional communication between DA neurons was investigated in rat brain slices. Tracer coupling was observed in postnatal day 5 (P5) to P10 and P15-P25 rats. Dual whole-cell patch-clamp recordings revealed that 96% of DA neurons were coupled by electrical synapses in P7-P10 rats, and 20% were coupled in P17-P21 rats. These electrical synapses were mainly symmetrical and displayed strong low-pass filtering properties. When spontaneous firing activity was monitored, no significant synchronization was observed. Nevertheless, an efficient modulation of the spontaneous firing frequency of the postsynaptic cell occurred during injection of hyperpolarizing and depolarizing currents in the coupled presynaptic cell. Together, these observations demonstrate the existence of a fast communication between SNc DA neurons through electrical synapses.
Modality-Specific Cognitive Function of Medial and Lateral Human Brodmann Area 6
Authors: Tanaka Satoshi , Honda Manabu , Sadato Norihiro
Published: January 2005

Despite the fact that human Brodmann area 6 (BA6), a traditional “motor” area, is active during higher motor control involving various cognitive operations, the functional specialization within BA6 in the cognitive domain is essentially unknown. Furthermore, its functional relevance in cognition has been questioned because brain activity in BA6 during cognitive tasks has often been explained away as a concomitant, latent motor process. Therefore, we examined the structural-functional relationship of human BA6 in nonmotor cognitive functions and its functional relevance using both functional magnetic resonance imaging (fMRI) and repetitive transcranial magnetic stimulation (rTMS). Subjects performed mental-operation (MO) tasks in which they serially updated verbal and spatial mental representations (MO-v and MO-s). In the fMRI experiments, activity in the medial BA6 was more increased in MO-v, whereas the activity in the lateral BA6 in both hemispheres was more in MO-s. Low-frequency rTMS to the medial BA6 disrupted only the performance of MO-v, whereas rTMS to the lateral BA6 in both hemispheres disrupted only MO-s. Hence the converging results demonstrate a functional double dissociation in which medial BA6 has a critical role in updating verbal information and lateral BA6 has a role in updating spatial information. The present study provides direct physiological evidence of modality-specific cognitive function within human BA6.
Interactive Effects of Environmental Variability and Military Training on Stream Biota of Three Headwater Drainages in Western Louisiana
Authors: Williams Lance R. , Bonner Timothy H. , Hudson James D. , Williams Marsha G. , Leavy Tracy R. , Williams Casey S.
Published: January 2005

We collected fishes and macroinvertebrates seasonally from eight headwater streams in three different drainage basins (the Red, Calcasieu, and Sabine rivers) crossing Peason Ridge Training Area in west‐central Louisiana. Peason Ridge is part of the Fort Polk military training facility. We used multivariate analyses to test the effects of physical variables (i.e., current velocity, depth, and substrate), time (seasonal variability), drainage basin, and military training activities on assemblage structure. Tributaries of the Red River had the highest gradient and were predominated by shallow, swift‐flowing runs with sandy substrates. Southern tributaries of the Calcasieu and Sabine rivers were of lower stream gradient and contained deep, sluggish runs and pools with large amounts of woody debris and silt. Fish assemblages were structured primarily by military training and drainage basin. Faunal differences among drainage basins probably reflect differences in stream gradient. Fish assemblages in tributaries of the Sabine River were less diverse and showed evidence of historical degradation. Macroinvertebrate assemblages also were structured primarily by military training but had a strong seasonal component related to their short life cycles and high seasonal turnover. In contrast to fishes, macroinvertebrate assemblages were similar among drainages. Because military training was most intense in the Red River basin, its significance in these models probably represents differences in stream gradient among the basins because we found no negative effect on stream biota resulting from current training activities. Rather, historical logging and the resultant siltation coupled with isolation of populations by reservoirs are probable explanations for the changes in fish assemblages in tributaries of the Sabine River.
Age‐0 Black Crappie Abundance and Size in Relation to Zooplankton Density, Stock Abundance, and Water Clarity in Three Florida Lakes
Authors: Dockendorf Kevin J. , Allen Micheal S.
Published: January 2005

Crappies Pomoxis spp. are popular sport fishes but are often difficult to manage due to highly variable recruitment. To assess the factors influencing recruitment, we investigated the size and abundance of age‐0 black crappie P. nigromaculatus in relation to zooplankton density, adult stock abundance, and water clarity in three productive Florida lakes. Age‐0 black crappies were collected at Lakes Wauberg, Lochloosa, and Tarpon by use of surface and bottom trawls during the spring, summer, and fall of 2000 and 2001. Zooplankton abundance was measured concurrently with trawl sampling. Early‐summer juvenile abundance was positively related to stock abundance during the previous fall among lakes, indicating a relationship between stock size and juvenile black crappie abundance. Early‐summer juvenile abundance was positively related to juvenile abundance in the fall (i.e., at the end of the first summer), suggesting that year‐class strength was set by early summer in all lakes. Lake Lochloosa had the highest crustacean zooplankton abundance in both years, but this lake had the smallest age‐0 black crappie size and intermediate age‐0 fish abundance. Thus, we found no relationship between crustacean zooplankton density and black crappie size across lakes. Reduced Secchi depths due to high chlorophyll‐a values and wind resuspension of sediments may have reduced feeding efficiency for age‐0 black crappies at Lake Lochloosa relative to the other lakes. Age‐0 black crappie abundance and size during fall were not predicted solely by food availability, stock abundance, or water clarity, suggesting that these factors interacted to influence recruitment through the first year of life.
Development of a Morphological Index of the Nutritional Status of Juvenile Largemouth Bass
Authors: Smith Chris D. , Higgins Christopher L. , Wilde Gene R. , Strauss Richard E.
Published: January 2005

We describe the morphological changes associated with starvation in larval largemouth bass Micropterus salmoides and develop bivariate and multivariate morphological indices of nutritional status. We obtained hatchery‐reared largemouth bass, raised them until completion of fin development, and divided them into two randomized experimental groups of fed and unfed fishes. Fed fishes were provided with newly hatched brine shrimp twice daily. We quantified morphological changes in body shape using 23 morphometric characters. After only 3 d of food deprivation, we were able to detect statistically significant differences in morphology between the fed and unfed fish using multivariate analysis. The magnitude of the mean difference increased over time. An unexpected result suggested that a simple, bivariate ratio of standard length to body depth at the anus was almost as efficient and robust at classifying fed and unfed largemouth bass from an independent data set as a multivariate index based on all 23 morphometric characters. The relative ease of use, combined with a small level of misclassification error rate and a firm foundation in whole‐body changes, makes these ratio indices effective tools for detecting food deprivation in larval largemouth bass.
Competition between Hatchery‐Reared and Wild Juvenile Chinook Salmon in Enclosures in the Sacramento River, California
Authors: Weber Edward D. , Fausch Kurt D.
Published: January 2005

We conducted two types of experiments in the upper Sacramento River, California, to test the effects of hatchery‐reared juvenile Chinook salmonOncorhynchus tshawytschaon the emigration, growth, and survival of their wild counterparts. In 3 years of displacement experiments, emigration rates from 8‐m2enclosures into downstream traps were similar between control enclosures that contained 40 wild fish and treatment enclosures to which 33 or 40 hatchery fish were also added. The mean number of wild fish in enclosures at the end of experiments differed by less than one fish between treatments and controls during all 3 years, indicating that hatchery fish prompted few wild fish to emigrate. In 2 years of competition experiments wherein fish could not emigrate, the enclosures contained wild fish (40 fish), wild fish plus hatchery fish (40 wild fish plus 33 or 40 hatchery fish), or wild fish at the same total density as the treatment with wild plus hatchery fish (73 or 80 wild fish). During 2001, survival and specific growth rates of wild fish were similar among treatments, probably because resources were not limiting. During 2002, survival was similar among treatments, but the mean specific growth rate was 0.008 g/d higher in the treatment with 40 wild fish than in the treatment with wild plus hatchery fish (95% confidence interval (CI), 0.005–0.011 g/d). These data indicated a negative effect on wild fish growth of adding hatchery fish. The specific growth rate in the high‐density wild fish treatment was intermediate and 0.003 g/d higher than in the treatment with hatchery fish (95% CI, −0.0005 to +0.006 g/d), providing some evidence that hatchery fish had a greater negative effect on wild fish growth than an equal density of wild fish did.
Effects of Temperature on Survival and Development of Early Life Stage Pacific and Western Brook Lampreys
Authors: Meeuwig Michael H. , Bayer Jennifer M. , Seelye James G.
Published: January 2005

We examined the effects of temperature (10, 14, 18, and 22°C) on survival and development of Pacific lampreys Lampetra tridentata and western brook lampreys L. richardsoni during embryological and early larval stages. The temperature for zero development was estimated for each species, and the response to temperature was measured as the proportion of individuals surviving to hatch, surviving to the larval stage, and exhibiting abnormalities at the larval stage (i.e., malformations of the body). The estimated temperature for zero development was 4.85°C for Pacific lampreys and 4.97°C for western brook lampreys. Survival was greatest at 18°C, followed by 14, 10, and 22°C, significant differences being observed between 22°C and the other temperatures. Overall survival was significantly greater for western brook lampreys than for Pacific lampreys; however, the overall difference in proportion of individuals surviving was only 0.02. Overall survival significantly decreased from the time of hatch (proportion surviving = 0.85) to the larval stage (0.82; i.e., during the free‐embryo stage). The proportion of individuals exhibiting abnormalities at the larval stage was greatest at 22°C, followed by 18, 10, and 14°C, significant differences being observed between 22°C and the other temperatures. These data provide baseline information on the thermal requirements of early life stage Pacific and western brook lampreys and will aid in assessment and prediction of suitable spawning and rearing habitats for these species.
A Laboratory Evaluation of Poststocking Predatory Losses for Cultured Largemouth Bass
Authors: Schlechte J. Warren , Betsill Robert K. , Buckmeier David L.
Published: January 2005

Stocking fish into preexisting fish communities is not always successful. Although there may be many reasons why stockings fail, predation is perhaps the most likely reason. Reducing predation by allowing fish to become accustomed to their new environment before release (i.e., habituation) may improve stocking efficiency. We evaluated the effect of habituation on predation of stocked, hatchery‐reared fingerling Florida largemouth bass Micropterus salmoides floridanus (30–64 mm total length) in simple (i.e., open‐water) and structurally complex (i.e., with vegetation and cobble) habitats in indoor tanks. We found that fingerling largemouth bass survival significantly increased (P < 0.004) from 26% to 46% when fish were habituated in a predator‐free enclosure for at least 15 min. Surviving fish spent most (95%) of their time in the structurally complex habitat. However, the survival of all fish stocked in structurally complex habitat did not differ from that of all fish stocked in open water (P = 0.61). Although predation on nonhabituated, hatchery‐reared largemouth bass approached 75%, we found that short‐term habituation can enhance survival of stocked largemouth bass, as manifested by improved predator avoidance. This suggests that habituating fingerling largemouth bass before stocking may result in substantial increases in survival.
Age‐0 Gizzard Shad Abundance is Reduced in the Presence of Macrophytes: Implications for Interactions with Bluegills
Authors: Michaletz Paul H. , Bonneau Joseph L.
Published: January 2005

The abundance of gizzard shad Dorosoma cepedianum may be reduced in the presence of macrophytes, which may lessen the frequently observed negative interactions with coinhabiting bluegills Lepomis macrochirus. We used a series of experimental pond studies and a small‐lake data set to examine relationships among gizzard shad, bluegills, and macrophytes. Fall age‐0 gizzard shad abundance was lower in vegetated experimental ponds than in unvegetated ponds, but mean total length (TL) did not differ. Larval gizzard shad abundance did not differ between vegetated and unvegetated ponds, but the relative survival of age‐0 gizzard shad (ratio of fall juveniles to the total number of larvae collected) was higher in unvegetated ponds. In ponds with macrophyte coverage ranging from 0% to 100%, age‐0 gizzard shad abundance declined with increasing macrophyte coverage; however, age‐0 bluegill abundance was unrelated to macrophyte coverage. The abundance and size of age‐0 gizzard shad and age‐0 bluegills were unrelated in these ponds. By examining the small‐lake data, we found that the proportion of lakes containing gizzard shad decreased with increasing macrophyte coverage. The proportion of bluegill populations containing large adults (>203 mm TL) increased with macrophyte coverage for lakes with gizzard shad but not for lakes without gizzard shad. Although the actual mechanisms are not clear, we suggest that competitive interactions between gizzard shad and adult bluegills are density dependent and lessen with increasing macrophyte coverage because of decreasing gizzard shad abundance.
A Nonlethal, Rapid Method for Assessing the Somatic Energy Content of Migrating Adult Pacific Salmon
Authors: Crossin Glenn T. , Hinch Scott G.
Published: January 2005

Traditional methods for determining the energy content of fish involve either chemical assays of lipid and protein levels (proximate analyses) or tissue combustion (bomb calorimetry). In studies of migrating Pacific salmon Oncorhynchus spp., entire fish need to be homogenized prior to analysis, as energy reserves are stored along a head‐to‐tail gradient and change along this gradient depending on the stage of upriver migration. The logistics and costs associated with transporting carcasses to the laboratory can be prohibitive. Also, many populations of Pacific salmon are at risk of extinction, so lethal sampling is often not an option. Few reliable and practical methods exist that enable rapid and nonlethal energy determinations of large fish in the field. We evaluated a handheld microwave energy meter as a means of estimating whole‐body energy concentrations. In 2002 and 2003, we collected sockeye salmon O. nerka from several stocks during their coastal and upriver migration through the Fraser River watershed (British Columbia). For each stock, we sampled fish from various locales ranging from ocean to spawning areas. Fish somatic tissues were interrogated at four body positions; however, the two most anterior positions produced the most accurate energy information. It took less than 30 s per fish to collect these data. We found strong regression relationships between somatic lipid percentage (R2 = 0.93; P < 0.001) and gross somatic energy density (R2 = 0.94; P < 0.001) measured by whole‐carcass proximate analyses and loge transformed energy meter readings. The slopes and intercepts of these relationships did not differ among stocks or years.
Experimental study of feasibility in kinetically‐controlled reactive distillation
Authors: Chiplunkar Madhura , Hong Mooho , Malone Michael F. , Doherty Michael F.
Published: January 2005

Bifurcation studies predict limited ranges of feasibility for products in certain reactive distillations. These are closely related to the bifurcations in the singular points of dynamic models for simple reactive distillation (isobaric open evaporation with liquid phase reaction). A new dynamic model is described with constant vapor rate together with an experimental study for the reactive distillation of acetic acid with isopropanol to produce isopropyl acetate, catalyzed by Amberlyst‐15 ion‐exchange resin. An experimental apparatus with real‐time measurement of liquid compositions based on Fourier transform infrared (FTIR) spectroscopy is described, and used to follow the composition dynamics at several initial conditions and Damköhler numbers (Da). The experimental results match model predictions that show four regions of behavior. For Da ≈ 1, these show a stable node at acetic acid and several other fixed points as saddles. However, near Da ≈ 2, both isopropanol and acetic acid are stable nodes and a quaternary singular point appears. The presence of two stable nodes requires the presence of a distillation boundary and, therefore, a limited feasibility for the bottom product compositions from continuous reactive distillation. For the reaction rates studied, the model predictions are closely consistent with the experimental findings, and are robust to variations in the vapor rate. These experiments are among the first to analyze the dynamics and feasibility in a kinetically‐controlled reactive distillation and are consistent with previous studies for the reaction equilibrium limit, indicating the formation of a reactive azeotrope. © 2005 American Institute of Chemical Engineers AIChE J, 51: 464–479, 2005
Resistivity and thermal reproducibility of carbon black and metallic powder filled silicone rubber heaters
Authors: Park Eun‐Soo , Wook Jang Lee , Yoon Jin‐San
Published: January 2005

Flexible heaters were prepared by extruding platinum‐catalyzed silicone rubber composites with conductive carbon black (CB) and metallic fillers. The conductor resistivity of the extruded heaters decreased in order of conductive titanium dioxide (TiO2) > aluminum powder ≈ zinc powder > copper powder. Thermoelectric switching phenomena were investigated for the silicone rubber/CB/metallic powder systems. The positive temperature coefficient effect was dependent mainly on the CB content rather than on the content of the metallic powders. Resistivity and thermal reproducibility of the extruded heaters were also investigated by periodically applying AC voltage of 110 V. The heaters containing copper and TiO2 powders exhibited excellent electrical reproducibility. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1122–1128, 2005
Conformational investigations on analogs of inflammation response inducing chemotactic tripeptide fMLP
Authors: Rathore Ravindranath Singh
Published: January 2005

Conformations of three analogs of for–L‐Met–L‐Leu–L‐Phe–OH (fMLP), which initiates inflammatory response by interaction with the formyl peptide receptor (FPR), have been investigated by the application of the X‐ray crystallographic technique. The investigated analogs of fMLP peptides are as follows: for–L‐Met‐1–amino‐1–cyclooctane–carbonyl(Ac8c)–L‐Phe–OMe (1); for–L‐Met–L‐Leu–L‐p‐iodo‐Phe–OH (2); and for–L‐Met–di‐n‐propylglycyl(Dpg)–L‐Phe–OMe (3). The peptide backbone in 1 and 3 is constrained at position 2 of fMLP by the introduction of Cα,α‐disubstituted glycines. In peptide 2, Phe–OMe is substituted by p‐iodo‐Phe–OH. Crystal structures reveal an overall folded conformation adopted by 1 and 2. The former is folded in the type II β‐turn, which is stabilized by an intramolecular 1 ← 4 (formyl) CO · · · HN (Phe) hydrogen bond, whereas the latter is folded in an open turn without any intramolecular hydrogen bond. On the other hand, peptide 3 has an extended conformation, and two different molecules (3a, 3b) in a crystallographic asymmetric unit form an antiparallel β‐sheet‐like structure. In 1 and 3, residues Ac8c and Dpg adopt left‐handed helical and fully extended (C5) conformations, respectively. The cyclooctane ring in Ac8c acquires a boat‐chair conformation. Crystal packing of 1 is characterized by the association of aliphatic‐aromatic rings via a CH · · · π interaction. In the crystal of 2, contrary to the usual observations, peptides are interlinked via networks of head‐to‐tail hydrogen bond and π · · · π interactions, which are generally observed to be mutually exclusive. The structure–function mechanism of the ligand–receptor interaction is discussed. © 2005 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 80: 651–664, 2005

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Incidence and follow‐up of patients with focal prostate carcinoma in 2 screening rounds after an interval of 4 years
Authors: Postma Rensbe , de Vries Shijn H. , Roobol Monique J. , Wildhagen Mark F. , Schröder Fritz H. , van der Kwast Theo H.
Published: January 2005

BACKGROUND

Focal carcinoma detected by needle biopsy has been a common finding since prostate‐specific antigen (PSA)‐based screening was introduced. Clinicopathologic features in patients with focal prostate carcinoma who underwent radical prostatectomy (RP) or who were treated with watchful waiting (WW) were analyzed to detect clinical predictors for disease progression during follow‐up.

METHODS

Patients were selected from the European Randomized Screening study for Prostate Cancer. Focal carcinoma on sextant biopsy was defined as ≤ 3.0 mm involvement by tumor in 1 biopsy core lacking Gleason pattern 4 or 5. PSA doubling time was used in the WW group as a marker of disease progression.

RESULTS

The proportion of patients with focal prostate carcinoma increased significantly from 16% in the first screening round to 29% in the second screening round. One hundred eighteen men underwent RP, and 108 men were treated with WW. The median tumor volume was 0.13 mL. PSA level and prostate volume were predictive for tumor volume in a multivariate regression analysis. A PSA density cut‐off level of ≤ 0.1 ng/mL/cm3 predicted organ‐confined tumor (< 0.5 mL) in 94% of patients. Positive surgical margins were predictive for PSA recurrence. Four patients in the RP group had PSA recurrence at follow‐up. PSA doubling times < 2 years, < 3 years, and < 4 years were noted in 4.9%, 14.6%, and 22.0% of patients in the WW group, respectively.

CONCLUSIONS

The median tumor volume was small (0.13 mL). A comparison between PSA recurrence in the RP group and PSA doubling time in the WW group showed a significantly more favorable outcome after RP if a PSA doubling time of < 3 years or < 4 years was chosen as a marker for disease progression in the WW group. A WW policy with delayed curative intent may be recommended in patients ages 55–75 years with focal carcinoma and PSA density < 0.1 ng/mL/cm3. Cancer 2005. © 2005 American Cancer Society.
Interactive measurement and characterization of DNA molecules by analysis of AFM images
Authors: Marek J. , Demjénová E. , Tomori Z. , Janáček J. , Zolotová I. , Valle F. , Favre M. , Dietler G.
Published: January 2005

Background

In the past few years, computer‐based analysis of atomic‐force microscopic images has acquired increasing importance for studying biomolecules such as DNA. On the one hand, fully automated methods do not allow analysis of complex shapes; on the other hand, manual methods are usually time consuming and inaccurate. The semiautomated approach presented in this report overcomes the drawbacks of both methods.

Methods

Two kinds of images were analyzed: computer‐generated filaments that modeled circular DNA molecules on a surface and real atomic‐force microscopic images of DNA molecules adsorbed on an appropriate substrate surface.

Results

The algorithm was tested on a group of 140 simulated and 189 real plasmids with a nominal length of 913 nm. The accuracy of the length measurement was statistically evaluated on the ensemble of molecules, with particular attention to the influence of the noise. Mean contour lengths of 912 ± 5 nm and 910 ± 47 nm were found for simulated and real plasmids, respectively. The measured end‐to‐end distance of λ‐DNA molecules as a function of their contour length is reported, from which it is possible to estimate the stiffness of the DNA molecules adsorbed onto a surface; the value obtained for the DNA persistence length (42 ± 5 nm) is consistent with values measured by other imaging techniques.

Conclusions

An interactive algorithm for DNA molecule measurements based on the detection of the filament ridge line in a digitized image is presented. The simulation of artificial filaments combined with the experimental data demonstrates that the proposed method can be a valuable tool for the DNA contour length evaluation, especially in the case of complex shapes where the use of automatic methods is not possible. © 2005 Wiley‐Liss, Inc.
Quantification of gliadin levels to the picogram level by flow cytometry
Authors: Capparelli Rosanna , Ventimiglia Ilaria , Longobardo Luigi , Iannelli Domenico
Published: January 2005

Background

Celiac disease is a widely prevalent enteropathy caused by intolerance to gliadin, one of the gluten proteins. We developed two methods for the analysis of gliadin levels. Both methods use flow cytometry and rat antibodies against a 16‐residue peptide of gliadin. The peptide is common to the α‐, β‐, γ‐, and ω‐gliadins.

Methods

In the one‐site assay, the antigen (gliadin standard or food extract) was adsorbed on 3‐μm latex particles. Sensitized particles were then incubated, in this order, with rat anti‐gliadin peptide antibodies and anti‐rat immunoglobulin G antibodies labeled with fluorescein isothiocyanate. In the two‐site assay, the antigen was trapped on the latex particles by rat anti‐gliadin antibodies and then measured by the same antibodies labeled with fluorescein.

Results

Detection limits were 1 ng/ml for the one‐site assay and 10 pg/ml for the two‐site assay. The two‐site assay displayed gliadin at concentrations above the limit proposed by the Codex Alimentarius in 2 of 40 gluten‐free products.

Conclusion

There is a growing concern that gliadin, even when present in gluten‐free foods within the limit fixed by the Codex Alimentarius, over the long term may become toxic to patients with celiac disease. The techniques described in this study provide an opportunity to further decrease the acceptable limit of gliadin in gluten‐free foods. © 2005 Wiley‐Liss, Inc.
Variational data assimilation for Hamiltonian problems
Authors: Watkinson L. R. , Lawless A. S. , Nichols N. K. , Roulstone I.
Published: January 2005

We investigate the conservation properties of Hamiltonian systems in variational data assimilation. We set up a four‐dimensional data assimilation scheme for the two‐body (Kepler) system using a symplectic scheme to model the non‐linear problem. We use our completed scheme to investigate the observability of the system and the effect of different background constraints. We find that the addition of these constraints gives an improved solution for the cases we have investigated. Copyright © 2005 John Wiley & Sons, Ltd.
Laboratory for internal gravity‐wave dynamics: the numerical equivalent to the quasi‐biennial oscillation (QBO) analogue
Authors: Wedi Nils P. , Smolarkiewicz Piotr K.
Published: January 2005

We have extended the classical terrain‐following coordinate transformation of Gal–Chen and Somerville to a broad class of time‐dependent vertical domains. The proposed extension facilitates modelling of undulating vertical boundaries in various areas of computational fluid dynamics. The theoretical development and the efficient numerical implementation have been documented in the context of the generic Eulerian/semi‐Lagrangian, non‐oscillatory forward in time (NFT), nonhydrostatic model framework. In particular, it allows the simulation of stratified flows with intricate geometric, time‐dependent boundary forcings, either at the top or at the bottom of the domain. We have applied our modelling framework in the direct numerical simulation of the celebrated laboratory experiment of Plumb and McEwan creating the numerical equivalent to their quasi‐biennial oscillation (QBO) analogue. The QBO represents a conspicuous example of a fundamental dynamical mechanism with challenging detail, which is difficult to deduce from experimental evidence alone. A series of 2D and 3D simulations demonstrate the ability to reproduce the laboratory results. The numerical experiments identify the developing periodically reversing mean flow pattern primarily as a wave–wave mean flow interaction‐driven phenomenon. The results not only enhance the confidence in the numerical approach but further elevate the importance of the laboratory setup in its fundamental similarity to the atmosphere, while allowing the study of the principal atmospheric mechanisms and their numerical realizability in a confined ‘laboratory’ environment. Copyright © 2005 John Wiley & Sons, Ltd.
Angiopoietin 1 prevents retinal detachment in an aggressive model of proliferative retinopathy, but has no effect on established neovascularization
Authors: Nambu Hiroyuki , Umeda Naoyasu , Kachi Shu , Oshima Yuji , Akiyama Hideo , Nambu Rie , Campochiaro Peter A.
Published: January 2005

Vascular endothelial growth factor (VEGF) plays a central role in vasoproliferative diseases in the retina, however, other gene products modulate its effects. The angiopoietins are particularly important in this regard. Angiopoietin 2 (Ang2) collaborates with VEGF to stimulate neovascularization (NV) in some situations, but in other situations causes regression of NV. Ang2 also causes a transient increase in vascular density during retinal vascular development. In this study, we sought to determine if Ang1 has similar activities. The effects of Ang1 were tested in double transgenic mice with inducible expression of Ang1. Increased expression of Ang1 in the retina during retinal vascular development did not cause a detectable alteration in vascular density. Also, unlike Ang2, increased expression of Ang1 had no effect on established retinal or choroidal NV. However, when Ang1 expression was initiated simultaneously with that of VEGF, it strongly suppressed VEGF‐induced NV and prevented retinal detachment. These data indicate that the timing of Ang1 expression is a critical determinate of its effects on VEGF‐induced NV in the retina; it effectively blocks the initiation and progression of NV, but cannot reverse established NV or reduce leakage from NV. These data suggest that increased expression of Ang1 may be a good strategy for prophylaxis of retinal NV, but is unlikely to be effective as monotherapy of established NV. © 2005 Wiley‐Liss, Inc.
Catalytic 1,3‐Cyclohexadiene Homopolymerization and Regioselective Copolymerization with Ethylene
Authors: Heiser Dirk E. , Okuda Jun , Gambarotta Sandro , Mülhaupt Rolf
Published: January 2005

Summary: 1,3‐Cyclohexadiene (CHD) was homo‐ and copolymerized by means of diimine nickel complexes and various substituted titanium based half‐sandwich complexes activated with methylaluminoxane (MAO). Soluble polycyclohexadienes were produced with the constrained geometry catalyst [Me2Si(NtBu)(Me4Cp)]TiCl2 (CBT) (Cp = cyclopentadienyl, Me = methyl). Only in the presence of CBT/MAO soluble high molecular weight CHD copolymers with ethylene were obtained. The CHD incorporation was varied between 0 and 12.3 mol‐%. According to NMR analysis the CHD/ethylene copolymerization is highly regioselective, accounting for exclusive formation of 1,4‐cyclohexene units randomly distributed in the polyethylene backbone.

13C NMR spectra of 1,4‐poly(1,3‐cyclohexadiene‐co‐ethylene) with 6.8 mol‐% CHD content in the copolymer.

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13C NMR spectra of 1,4‐poly(1,3‐cyclohexadiene‐co‐ethylene) with 6.8 mol‐% CHD content in the copolymer.
Novel Partially Fluorinated Copolymers: Evidence of the Effect of Fluorine on the Reactivity of the Unfluorinated Comonomer Units
Authors: Lazzari Massimo , Scalarone Dominique , Castelvetro Valter , Signori Francesca , Chiantore Oscar
Published: January 2005

Summary: A conventional free‐radical polymerization of vinyl or propenyl ethers with acrylic or methacrylic monomers with fluorine substitution either in the main chain or in the ester groups has permitted us to obtain a series of copolymers with substantially different fluorine contents and distributions to be obtained. Such copolymers were considered as model compounds to offer new valuable insights as to the influence of fluorinated moieties on the overall stability and, more specifically, on their reactivity with atmospheric oxygen under environmental‐like conditions. Depending on the relative position of the fluorine atoms with respect to the common active center of oxidation, the influence ranges from a simple slowing down of the process to a complete redirection towards an otherwise secondary mechanism of oxidation.

FT‐IR spectra of the carbonyl region of three novel fluorinated copolymers after oxidation.

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FT‐IR spectra of the carbonyl region of three novel fluorinated copolymers after oxidation.
Differential pattern of hand‐tapping compromise in vascular versus idiopathic parkinsonism: A study based on computerized movement analysis
Authors: Bäzner Hansjörg , Schanz Jurik , Blahak Christian , Grips Eva , Wöhrle Johannes C. , Hennerici Michael
Published: January 2005

We tested the characteristics and the differential pattern of upper extremity motor compromise, comparing hand tapping in patients with subcortical vascular encephalopathy (SVE; n = 18), idiopathic Parkinson's disease (PD; n = 18), and in healthy controls (n = 18). Both patient groups showed significant compromise in hand tapping compared with that in controls, with higher coefficients of variability (CV) regarding tapping amplitude and angular velocity, determined using a computerized movement analysis system. A differential tapping pattern in both patient groups could be demonstrated in that patients with PD showed lower tapping amplitudes than patients with SVE. Both patient groups displayed abnormalities in tapping rhythmicity compared with that in the control group. © 2005 Movement Disorder Society