bluuebunny/crossref_metadata_2025 huggingface dataset:
From Proterozoic strata to a synthesized seismic reflection trace: implications for regional seismic reflection patterns in northwestern Canada
Authors: Cook Frederick A , Siegel Samantha M
Published: March 2007

Calculation of a synthetic seismic reflection trace from detailed descriptions of exposed Proterozoic strata in northwestern Canada permits correlation of reflections on regional seismic profiles to surface outcrop. Approximately 5.4 km (composite thickness) of Paleo- and Mesoproterozoic strata are exposed in the Muskwa anticlinorium that is located within the foreland of the Cordillera in northeastern British Columbia. The Tuchodi anticline is the easternmost structure of the Muskwa anticlinorium and has the deepest levels of Proterozoic strata exposed. At this location, prominent seismic reflection layering rises toward the surface and is easily correlated to the deeper formations of the Muskwa assemblage stratigraphy. These layers are followed westward into the middle crust, where they are overlain by dramatically thickened (by about five times) strata, primarily of the Tuchodi Formation. Along the same line of section, the Muskwa assemblage reflections overlie additional subparallel layered reflections at depth whose lithology and origin are unknown. However, coupled with other observations, including regional refraction results that indicate the crustal layers have both low seismic p-wave velocities and low ratios of p- and s-velocities, regional gravity observations that indicate the layers are low density, and correlation to similar layers on other seismic profiles that exhibit characteristic seismic stratigraphic features, the subparallel layers that are present beneath the known Muskwa assemblage are most easily interpreted as layered Proterozoic (meta-) sedimentary rocks. These results provide the basis for interpreting the Muskwa anticlinorium as a crustal-scale structure that formed when a deep basin of Proterozoic strata was inverted and thrust over an ~20 km high footwall ramp during Cordilleran orogenesis.
Tectonic implications of 40Ar/39Ar muscovite dates from the Mt. Haley stock and Lussier River stock, near Fort Steele, British Columbia
Authors: Larson Kyle P , Price Raymond A , Archibald Douglas A
Published: March 2007

The Mt. Haley and Lussier River stocks are located northeast of Cranbrook, B.C. near the south end of the Western Main Ranges of the Southern Canadian Rocky Mountains. Both are multiphase, potassium-feldspar porphyritic monzonite plutons that intrude lower Paleozoic miogeoclinal strata. They crosscut and thermally overprint the Lussier River fault and the thrust and fold structures in the east flank of the Purcell anticlinorium and the west limb of the Porcupine Creek anticlinorial fan structure. Muscovite from the Mt. Haley stock yielded a 40Ar/39Ar plateau age of 108.2 ± 0.7 Ma (2σ), and a single-crystal, step-heating analysis of muscovite from a skarn in the metamorphic aureole adjacent to the Lussier River stock gave a plateau date of 108.7 ± 0.6 Ma (2σ). These dates constrain the timing of thrusting and folding in this portion of the western Rocky Mountains and of the displacement along the Lussier River – St. Mary fault to pre-middle Albian.
Multiple deformation episodes at Myra Falls volcanic-hosted massive sulfide camp, central Vancouver Island, British Columbia, Canada
Authors: Jones Sarah , Berry Ron , Sinclair Briony
Published: March 2007

A detailed deformation history for central Vancouver Island was determined at Myra Falls volcanic-hosted massive sulfide camp with early ductile deformation overprinted by several distinct episodes of brittle deformation. Brittle structures were subdivided into separate groups based on their morphology, geometry, kinematics, and crosscutting relations. The central location of this study provides a link between previous deformation studies in northern and southern Vancouver Island. Late Paleozoic northeast–southwest compression (D1) produced open upright folds with variably developed north-northwest-striking axial planar cleavage zones (S1) and subhorizontal stretching lineations (L1) subparallel to F1 fold axes. Renewed northeast–southwest compression during the collision of Wrangellia and North America produced a second foliation (S2) in localized shear zones, slightly oblique to the dominant S1 foliation. These two events are recorded throughout Vancouver Island wherever the basement is exposed. Mid-Cretaceous northeast–southwest compression during D3 produced early steep conjugate strike-slip faults (D3a), overprinted by northeast- and southwest-dipping thrust faults and bedding-parallel shears (D3b). D3 structures have been previously recognized in northern Vancouver Island but not as far south as Myra Falls. North–south extension (D4) produced east, north, and east–southeast-striking normal faults. These faults consistently crosscut earlier D1–D3 structures and reactivate steep D3a faults. Normal faulting is correlated with the development of the Upper Cretaceous Nanaimo Basin, but no faults of this age have previous been reported from onshore studies. The youngest structures at Myra Falls are large northwest-striking, northeast-dipping thrust faults and steep west- to west-northwest-striking sinistral strike-slip faults formed during the D5 event. These faults are gouge-rich, wavy anastomosing structures, with cleaved wall-rock zones up to several metres wide. The D5 faults are correlated with Eocene deformation caused by the accretion of the Pacific Rim and Crescent Terranes along the southwestern margin of Vancouver Island. Myra Falls is the northernmost location to have been reported, at which the structures formed as part of the Cowichan fold and thrust belt.
Extreme sediment delivery events recorded in the contemporary sediment record of a montane lake, southern Coast Mountains, British Columbia
Authors: Schiefer Erik , Menounos Brian , Slaymaker Olav
Published: March 2007

The extreme sediment delivery regime of a montane catchment was examined through the analysis of recent lacustrine varve deposits recovered from a high-density sampling program. Years of anomalously high sediment yield from the Green Lake watershed were identified over a 70-year period (1930–2000) based on whole-lake varve deposit volumes. Intra-annual sediment delivery events were categorized and described for those anomalous years using historical hydroclimatic data and the stratigraphic record observed within inflow proximal sediment cores. Extreme sediment delivery coincided with high discharge conditions and elevated sediment availability resulting from (1) rapid glacier recession of the early twentieth century, (2) late-summer and autumn rainstorm-generated floods, and (3) freshet floods caused by unusual snowmelt conditions. The thickness and physical characteristics of varves vary among years that experienced different types of moderate and extreme sediment delivery events in relation to the defined average-regime depositional model. Several hydroclimatic factors can interact to produce composite varve units of anomalous thickness. In some cases, geomorphic events, such as landslides and channel changes, contributed to extreme sediment delivery in the Green Lake catchment. The interaction of these geomorphic effects, coupled with the variable nature of associated hydroclimatic functions, complicate paleoenvironmental assessments based on the lacustrine varve record.
Assessment of the relationship between emplacement of the Algoman plutons and regional deformation in the Rainy Lake region, Ontario
Authors: Czeck Dyanna M , Maes Stephanie M , Sturm Claire L , Fein Elizabeth M
Published: March 2007

The Algoman suite of granites and granodiorites, located within the Rainy Lake region of the Superior Province, intruded the Wabigoon–Quetico subprovince boundary about 2686 Ma. Deformation occurred during the late Archean collision between the Wabigoon and Wawa volcanic arcs. The Algoman plutons are the youngest rocks in the region. Their apparent lack of macroscopic deformation fabrics has led previous researchers to use their age as a constraint for the cessation of regional deformation. However, contrasting competence between the relatively rigid granites and surrounding volcanic and metasedimentary rocks suggests that obvious deformation fabrics may not be observed in the plutons even if they were present during deformation. A field, anisotropy of magnetic susceptibility (AMS), gravity inversion model, and microstructural study were undertaken on two neighboring Algoman plutons to determine their emplacement history relative to the regional deformation. There is a steep macroscopic foliation in the adjacent rocks and in parts of the plutons. The magnetic foliation is very strong and roughly coincident with the field foliations. The gravity inversion models indicate that the plutons are relatively shallow (1 km and 4.5 km at their deepest points), and their shapes are consistent with emplacement during dextral transpression. Quartz microstructures, such as undulose extinction and subgrain formation, indicate that there was some solid-state deformation accommodated by dislocation creep mechanisms. The field, AMS, gravity, and microstructural evidence indicate that the plutons were most likely emplaced syntectonically. Thus, the pluton age does not provide a conclusive constraint to the cessation of regional deformation.
The sequence and correlation of Early Ordovician (Arenig) graptolite faunas in the Richardson Trough and Misty Creek Embayment, Yukon Territory and District of Mackenzie, Canada
Authors: Jackson D E , Lenz A C
Published: March 2007

Four graptolite biozones are recorded from the Arenig portion of the Road River Group in the Richardson and Mackenzie mountains in the Yukon and Northwest Territories. In ascending order, these zones are Tetragraptus approximatus, Pendeograptus fruticosus, Didymograptus bifidus, and Parisograptus caduceus australis (new). The Castlemainian stage may be represented by nongraptolitic massive bedded chert. The Arenig–Llanvirn boundary is drawn below the first occurrence of Undulograptus austrodentatus. Fifty-four graptolite taxa are present, and 16 of these species and subspecies are recorded for the first time in this deep-water biotope, namely, Didymograptus? cf. adamantinus, D. asperus, D. dilatans, D. cf. kurcki, D. validus communis, Holmograptus aff. leptograptoides, H. sp. A, Isograptus? sp. nov. A, I. ? dilemma, Keblograptus geminus, Pseudisograptus manubriatus harrisi, Ps. m. koi, Ps. m. janus, Ps. cf. tau, Xiphograptus lofuensis, and Zygograptus cf. abnormis.
Shallow faults, Upper Cretaceous clinoforms, and the Colonsay Collapse, Saskatchewan
Authors: Gendzwill Don , Stauffer Mel
Published: March 2007

Reflection seismic data in the vicinity of the Colonsay potash mine near Saskatoon, Saskatchewan, reveal numerous shallow normal faults with vertical displacements of as much as 25 m. The faults cut the glacial deposits and Upper Cretaceous rocks to a maximum depth of about 400 m. Horizontal length ranges from a few hundred to a few thousand metres. Similar faults are also exposed in several widely separated open-pit coal mines of southern Saskatchewan and may be common elsewhere in the prairies. Such faulting is considered to be a result of Tertiary to Quaternary extensional tectonics and may have been aided in this region by the melting of gas hydrates. The study area includes the east flank of the Colonsay Collapse, a subsidence structure caused by dissolution and removal of salt in the 200 m thick Devonian Prairie Evaporite Formation. Salt was removed in two stages prior to or during early glacial time and in late-glacial time. Subsidence was gradual, with no observable faulting. A complex of clinoform structures about 120 m thick and prograding east-northeast occurs in the Upper Cretaceous Lea Park Formation in the study area and may correlate to the Alderson Member of southern Saskatchewan. Strong seismic reflections within the complex could be due to gas-filled porosity. Where undermined by salt removal in the Colonsay Collapse, the clinoform structures now form drape antiforms.
Redescription of Aigialosaurus dalmaticus Kramberger, 1892, a Cenomanian mosasauroid lizard from Hvar Island, Croatia
Authors: Dutchak Alex R , Caldwell Michael W
Published: March 2007

Redescription of the type and only specimen of Aigialosaurus dalmaticus (BSP 1902II501), an "aigialosaurian" squamate from the Cenomanian–Turonian of Hvar, Croatia, and, at the time of collection, the Italian island of Lesina, indicates that previous reviews of the specimen include erroneous anatomical interpretations. The type specimen presents a new and unique pelvic anatomy: the ilium of A. dalmaticus is an elongate element with well-developed anterior and posterior iliac processes. A scenario is presented for mosasaurid pelvic evolution, whereby the anteriorly elongate and dorsally directed ilium of mosasauroids is not derived from the forward rotation of the posterior iliac process, but rather the reduction of that process and the elaboration of the anterior iliac process. Recent phylogenetic analysis of Mosasauroidea finds A. dalmaticus to be the sistergroup to Opetiosaurus bucchichi and all other mosasaurids and "aigialosaurs." We examine the character state assignments for A. dalmaticus in that study and refute those assignments owing to the absence of preservation of all four characters states found to separate A. dalmaticus from O. bucchichi.
PI3K activation is required for PMA-directed activation of cSrc by AFAP-110
Authors: Walker Valerie G. , Ammer Amanda , Cao Zongxian , Clump Anne C. , Jiang Bing-Hua , Kelley Laura C. , Weed Scott A. , Zot Henry , Flynn Daniel C.
Published: March 2007

Activation of PKCα will induce the cSrc binding partner AFAP-110 to colocalize with and activate cSrc. The ability of AFAP-110 to colocalize with cSrc is contingent on the integrity of the amino-terminal pleckstrin homology (PH1) domain, while the ability to activate cSrc is dependent on the integrity of its SH3 binding motif, which engages the cSrc SH3 domain. The outcome of AFAP-110-directed cSrc activation is a change in actin filament integrity and the formation of podosomes. Here, we address what cellular signals promote AFAP-110 to colocalize with and activate cSrc, in response to PKCα activation or PMA treatment. Because PH domain integrity in AFAP-110 is required for colocalization, and PH domains are known to interact with both protein and lipid binding partners, we sought to determine whether phosphatidylinositol 3-kinase (PI3K) activation played a role in PMA-induced colocalization between AFAP-110 and cSrc. We show that PMA treatment is able to direct activation of PI3K. Treatment of mouse embryo fibroblast with PI3K inhibitors blocked PMA-directed colocalization between AFAP-110 and cSrc and subsequent cSrc activation. PMA also was unable to induce colocalization or cSrc activation in cells that lacked the p85α and -β regulatory subunits of PI3K. This signaling pathway was required for migration in a wound healing assay. Cells that were null for cSrc or the p85 regulatory subunits or expressed a dominant-negative AFAP-110 also displayed a reduction in migration. Thus PI3K activity is required for PMA-induced colocalization between AFAP-110 and cSrc and subsequent cSrc activation, and this signaling pathway promotes cell migration.
Significant contribution of liver nonparenchymal cells to metabolism of ammonia and lactate and cocultivation augments the functions of a bioartificial liver
Authors: Nedredal Geir I. , Elvevold Kjetil , Ytrebø Lars M. , Fuskevåg Ole-Martin , Pettersen Ingvild , Bertheussen Kjell , Langbakk Bodil , Smedsrød Bård , Revhaug Arthur
Published: March 2007

A bioartificial liver (BAL) will bridge patients with acute liver failure (ALF) to either spontaneous regeneration or liver transplantation. The nitrogen metabolism is important in ALF, and the metabolism of nonparenchymal liver cells (NPCs) is poorly understood. The scope of this study was to investigate whether cocultivation of hepatocytes with NPCs would augment the functions of a BAL (HN-BAL) compared with a BAL equipped with only hepatocytes (H-BAL). In addition, NPCs were similarly cultivated alone. The cells were cultivated for 8 days in simulated microgravity with serum-free growth medium. With NPCs, initial ammonia and lactate production were fivefold and over twofold higher compared with later time periods despite sufficient oxygen supply. Initial lactate production and glutamine consumption were threefold higher in HN-BAL than in H-BAL. With NPCs, initial glutamine consumption was two- to threefold higher compared with later time periods, whereas initial ornithine production and arginine consumption were over four- and eightfold higher compared with later time periods. In NPCs, the conversion of glutamine to glutamate and ammonia can be explained by the presence of glutaminase, as revealed by PCR analysis. Drug metabolism and clearance of aggregated gamma globulin, probes administered to test functions of hepatocytes and NPCs, respectively, were higher in HN-BAL than in H-BAL. In conclusion, NPCs produce ammonia by hydrolysis of amino acids and may contribute to the pathogenesis of ALF. High amounts of lactate are produced by NPCs under nonhypoxic conditions. Cocultivation augments differentiated functions such as drug metabolism and clearance of aggregated γ-globulin.
Development of contractile dysfunction in rat heart failure: hierarchy of cellular events
Authors: Daniels Marcel C. G. , Naya Taihei , Rundell Veronica L. M. , de Tombe Pieter P.
Published: March 2007

The cellular mechanisms underlying the development of congestive heart failure (HF) are not well understood. Accordingly, we studied myocardial function in isolated right ventricular trabeculae from rats in which HF was induced by left ventricular myocardial infarction (MI). Both early-stage (12 wk post-MI; E-pMI) and late, end-stage HF (28 wk post-Mi; L-pMI) were studied. HF was associated with decreased sarcoplasmic reticulum Ca2+ ATPase protein levels (28% E-pMI; 52% L-pMI). HF affected neither sodium/calcium exchange, ryanodine receptor, nor phospholamban protein levels. Twitch force at saturating extracellular [Ca2+] was depressed in HF (30% E-pMI; 38% L-pMI), concomitant with a marked increase in sensitivity of twitch force toward extracellular [Ca2+] (26% E-pMI; 68% L-pMI). Ca2+-saturated myofilament force development in skinned trabeculae was unchanged in E-pMI but significantly depressed in L-pMI (45%). Tension-dependent ATP hydrolysis rate was depressed in L-pMI (49%), but not in E-pMI. Our results suggest a hierarchy of cellular events during the development of HF, starting with altered calcium homeostasis during the early phase followed by myofilament dysfunction at end-stage HF.
Explaining Patterns of Neural Activity in the Primary Motor Cortex Using Spinal Cord and Limb Biomechanics Models
Authors: Trainin Ehud , Meir Ron , Karniel Amir
Published: March 2007

What determines the specific pattern of activation of primary motor cortex (M1) neurons in the context of a given motor task? We present a systems level physiological model describing the transformation from the neural activity in M1, through the muscle control signal, into joint torques and down to endpoint forces and movements. The redundancy of the system is resolved by biologically plausible optimization criteria. The model explains neural activity at both the population, and single neuron, levels. Due to the model's relative simplicity and analytic tractability, it provides intuition as to the most salient features of the system as well as a possible causal explanation of how these determine the overall behavior. Moreover, it explains a large number of recent observations, including the temporal patterns of single-neuron and population firing rates during isometric and movement tasks, narrow tuning curves, non cosine tuning curves, changes of preferred directions during a task, and changes of preferred directions due to different experimental conditions.
Apamin-Sensitive Calcium-Activated Potassium Currents (SK) Are Activated by Persistent Calcium Currents in Rat Motoneurons
Authors: Li X. , Bennett D. J.
Published: March 2007

Low voltage–activated persistent inward calcium currents (Ca PICs) occur in rat motoneurons and are mediated by Cav1.3 L-type calcium channels (L-Ca current). The objectives of this paper were to determine whether this L-Ca current activates a sustained calcium-activated potassium current (SK current) and examine how such SK currents change with spinal injury. For comparison, the SK current that produces the postspike afterhyperpolarization (mAHP) was also quantified. Intracellular recordings were made from motoneurons of adult acute and chronic spinal rats while the whole sacrocaudal spinal cord was maintained in vitro. Spikes/AHPs were evoked with current injection or ventral root stimulation. Application of the SK channel blocker apamin completely eliminated the mAHP, which was not significantly different in chronic and acute spinal rats. The Ca PICs were measured with slow voltage ramps (or steps) with TTX to block sodium currents. In chronic spinal rats, the PICs were activated at –58.6 ± 6.0 mV and were 2.2 ± 1.2 nA in amplitude, significantly larger than in acute spinal rats. Apamin significantly increased the PIC, indicating that there was an SK current activated by L-Ca currents (SKLcurrent), which ultimately reduced the net PIC. This SKLcurrent was not different in acute and chronic spinal rats. The SKAHPand the SKLcurrents were activated by different calcium currents because the mAHP/SKAHPwas blocked by the N, P-type calcium channel blocker ω-conotoxin MVIIC and was resistant to the L-type calcium channel blocker nimodipine, whereas the L-Ca and SKLcurrents were blocked by nimodipine. Furthermore, the SKAHPcurrent activated within 10 ms of the spike, whereas the SKLcurrent was delayed ∼100 ms after the onset of the L-Ca current, suggesting that the SKLcurrents were not as spatially close to the L-Ca currents. Finally, the SKLand the L-Ca currents were poorly space clamped, with oscillations at their onset and hysteresis in their activation and deactivation voltages, consistent with currents of dendritic origin. The impact of these dendritic currents was especially pronounced in 15% of motoneurons, where apamin led to uncontrollable L-Ca currents that could not be deactivated, even with large hyperpolarizations of the soma. Thus, although the SKLcurrents are fairly small, they play a critical role in terminating the dendritic L-Ca currents.
Combined Voltage and Calcium Epifluorescence Imaging In Vitro and In Vivo Reveals Subthreshold and Suprathreshold Dynamics of Mouse Barrel Cortex
Authors: Berger Thomas , Borgdorff Aren , Crochet Sylvain , Neubauer Florian B. , Lefort Sandrine , Fauvet Bruno , Ferezou Isabelle , Carleton Alan , Lüscher Hans-Rudolf , Petersen Carl C. H.
Published: March 2007

Cortical dynamics can be imaged at high spatiotemporal resolution with voltage-sensitive dyes (VSDs) and calcium-sensitive dyes (CaSDs). We combined these two imaging techniques using epifluorescence optics together with whole cell recordings to measure the spatiotemporal dynamics of activity in the mouse somatosensory barrel cortex in vitro and in the supragranular layers in vivo. The two optical signals reported distinct aspects of cortical function. VSD fluorescence varied linearly with membrane potential and was dominated by subthreshold postsynaptic potentials, whereas the CaSD signal predominantly reflected local action potential firing. Combining VSDs and CaSDs allowed us to monitor the synaptic drive and the spiking activity of a given area at the same time in the same preparation. The spatial extent of the two dye signals was different, with VSD signals spreading further than CaSD signals, reflecting broad subthreshold and narrow suprathreshold receptive fields. Importantly, the signals from the dyes were differentially affected by pharmacological manipulations, stimulation strength, and depth of isoflurane anesthesia. Combined VSD and CaSD measurements can therefore be used to specify the temporal and spatial relationships between subthreshold and suprathreshold activity of the neocortex.
Rate Coding Is Compressed But Variability Is Unaltered for Motor Units in a Hand Muscle of Old Adults
Authors: Barry Benjamin K. , Pascoe Michael A. , Jesunathadas Mark , Enoka Roger M.
Published: March 2007

The discharge of single motor units ( n = 34) in the first dorsal interosseus muscle and the fluctuations in force during steady contractions were measured across a range of index finger abduction forces in old adults (77.1 ± 6.9 yr, n = 20). These results were compared with previously reported data on 38 motor units from young adults (25.7 ± 5.7 yr). Both minimal and peak discharge rates increased with recruitment threshold, but the strength of these relations was notably weaker for the old adults. Minimal discharge rates were similar for young and old adults ( P = 0.77), whereas peak discharge rates were lower for old adults ( P < 0.01). Consequently, the range of rate coding for each motor unit was substantially less for the old adults (7.1 pps) compared with the young adults (12.1 pps, P < 0.01). However, the variability in motor-unit discharge was similar for young and old adults; the coefficient of variation of the interspike intervals was similar at recruitment (old: 25.4%, young: 27.1%, P = 0.39) and declined with an increase in discharge rate (old: 13.2%, young: 14.2%, P = 0.21). Furthermore, the fluctuations in force during steady isometric contractions (2–95% of maximal force) were similar for young and old adults, except that the relative variability at the lowest force was greater for the old adults. A computational model of motor-unit recruitment and rate coding incorporated the experimental observations and was able to match the measured and simulated values for force steadiness across the operating range of the muscle.
Endogenous Tachykinin Release Contributes to the Locomotor Activity in Lamprey
Authors: Pérez Carolina Thörn , Hill Russell H. , Grillner Sten
Published: March 2007

Tachykinins are present in lamprey spinal cord. The goal of this study was to investigate whether an endogenous release of tachykinins contributes to the activity of the spinal network generating locomotor activity. The locomotor network of the isolated lamprey spinal cord was activated by bath-applied N-methyl-d-aspartate (NMDA) and the efferent activity recorded from the ventral roots. When spantide II, a tachykinin receptor antagonist, was bath-applied after reaching a steady-state burst frequency (>2 h), it significantly lowered the burst rate compared with control pieces from the same animal. In addition, the time to reach the steady-state burst frequency (>2 h) was lengthened in spantide II. These data indicate that an endogenous tachykinin release contributes to the ongoing activity of the locomotor network by modulating the glutamate–glycine neuronal network responsible for the locomotor pattern. We also explored the effects of a 10-min exogenous application of substance P (1 μM), a tachykinin, and showed that its effect on the burst rate depended on the initial NMDA induced burst frequency. At low initial burst rates (∼0.5 Hz), tachykinins caused a marked further slowing to 0.1 Hz, whereas at higher initial burst rates, it instead caused an enhanced burst rate as previously reported, and in addition, a slower modulation (0.1 Hz) of the amplitude of the motor activity. These effects occurred during an initial period of ∼1 h, whereas a modest long-lasting increase of the burst rate remained after >2 h.
Inhibition of Hippocampal Matrix Metalloproteinase-3 and -9 Disrupts Spatial Memory
Authors: Wright John W. , Brown Travis E. , Harding Joseph W.
Published: March 2007

Memory consolidation requires synaptic reconfiguration dependent upon extracellular matrix (ECM) molecules interacting with cell adhesion molecules. Matrix metalloproteinase (MMP) activity is responsible for transient alterations in the ECM that may be prerequisite to hippocampal-dependent learning. In support of this hypothesis we have measured increases in MMP-3 and MMP-9 levels within the hippocampus and prefrontal cortex during Morris water maze training. The present investigation extends these findings by determining that infusion of an MMP inhibitor (FN-439) into the dorsal hippocampus disrupted acquisition of this task. In vitro fluorescence enzyme assays to determine the specificity of FN-439 against the catalytic domains of MMP-3 and MMP-9 indicated mean±SEMIC50sof 16.2±7.8 and 210.5±37.8μM, respectively, while in situ zymography using hippocampal sections treated with FN-439 indicated significant reductions in MMP gelatinase activity. These results suggest that compromising the ability of the dorsal hippocampus to reconfigure ECM molecules by inhibiting MMP activity interferes with appropriate spatial memory acquisition, and support a role for hippocampal MMPs in the phenomena of spatial memory acquisition and storage.
Neurobiology of Memory and Anxiety: From Genes to Behavior
Authors: Kalueff Allan V.
Published: March 2007

Interaction of anxiety and memory represents an essential feature of CNS functioning. This paper reviews experimental data coming from neurogenetics, neurochemistry, and behavioral pharmacology (as well as parallel clinical findings) reflecting different mechanisms of memory-anxiety interplay, including brain neurochemistry, circuitry, pharmacology, neuroplasticity, genes, and gene-environment interactions. It emphasizes the complexity and nonlinearity of such interplay, illustrated by a survey of anxiety and learning/memory phenotypes in various genetically modified mouse models that exhibit either synergistic or reciprocal effects of the mutation on anxiety levels and memory performance. The paper also assesses the putative role of different neurotransmitter systems and neuropeptides in the regulation of memory processes and anxiety, and discusses the role of neural plasticity in these mechanisms.
LTP after Stress: Up or Down?
Authors: Joëls Marian , Krugers Harm J.
Published: March 2007

When an organism is exposed to a stressful situation, corticosteroid levels in the brain rise. This rise has consequences for behavioral performance, including memory formation. Over the past decades, it has become clear that a rise in corticosteroid level is also accompanied by a reduction in hippocampal long-term potentiation (LTP). Recent studies, however, indicate that stress does not lead to a universal suppression of LTP. Many factors, including the type of stress, the phase of the stress response, the area of investigation, type of LTP, and the life history of the organism determine in which direction LTP will be changed.
Bombesin‐Like, Substance P and Vasoactive Intestinal Polypeptide Receptors in Fetal Cortical Homografts to Host Cortex and Spinal Cord
Authors: Moody Terry W. , Getz Reina L. , Goldberg William J. , Bernstein Jerald J.
Published: March 2007

Neuropeptide receptors were visualized in homografts of fetal cortex (E14) into adult rat cortex (immediate or 7 day delay) and spinal cord using in vitro autoradiographic techniques to explore the expression of peptide receptors in the same graft tissue in different central nervous system implantation sites. Receptors for bombesin (BN)‐like peptides developed in the grafts by 3 weeks postimplantation regardless of location or age of implantation pocket in host. After 4 weeks, the density of BN receptors was confined to the graft. In grafts to spinal cord, however, high densities of BN‐like receptors were not confined to the graft but were distributed throughout the spinal cord. In contrast, the density of vasoactive intestinal polypeptide (VIP) and substance P (SP) receptors was moderate and low to undetectable in the fetal grafts. The development of the peptide receptors studied was graft donor tissue specific since they
were not altered by central nervous system implantation site.
Removal and Reimplantation of the Parietal Cortex of Mice During the First Nine Days of Life: Consequences for the Barrelfield
Authors: Andrés Filipe
Published: March 2007

Vibrissal follicles on one side of the mouse whiskerpad are topologically connected to barrels in the contralateral somatosensory cortex. Barrels develop from postnatal day 3 to 6. Recently, I have observed that the barrelfields still develop in pieces of parietal cortex that were removed and reimplanted, in the same place and with the original orientation, on the day of birth, or on postnatal days 1 or 3. Now, two questions were asked: (i) Can the barrelfield form and/or remain in place after interrupting thalamocortical connections at different ages (from birth to postnatal day 9)? (ii) How does the cortex behave, in terms of cellular layers, after the interruption of thalamocortical connections?To answer these questions the parietal cortex was removed and reimplanted in the same place with the
original orientation, in 79 mice from a C3H strain Fifty‐one mice survived and were processed for histology.
Their brains were cut coronally to facilitate the identification of the limits of the reimplanted cortex and of its
cellular layering. In 29 cases the reimplanted cortex could be identified, and in 17 cases barrel‐like structures
had developed. The “barrelfields were obtained from coronal sections of each piece of reimplanted cortex, by means of a computer program which permitted reconstructing these pieces of cortex and rotating them in space. In this way, barrel‐like structures and “barrelfields” could be visualized as if obtained from sections made
tangential to the parietal cortex. “Barrelfields” were found in pieces of cortex reimplanted at different ages
up to postnatal day 9. Cortical layers appeared to be more close to normal in cases operated after postnatal
day 5.
Combined Vital Dye Labelling and Catecholamine Histofluorescence of Transplanted Ciliary Ganglion Cells
Authors: Sechrist John , Coulombe James N. , Bronner-Fraser Marianne
Published: March 2007

We have utilized the carbocyanine dye, DiI, to label suspensions of dissociated ciliary ganglion cells removed from 6 to 12 day old quail embryos. Some of the cells were injected into the trunk somites of 2.5 ‐ 3 day old chick embryos along pathways where neural crest cells migrate to form sensory and sympathetic ganglia, aortic plexuses and the adrenal medulla; the remainder of the cells were cultured to check their viability and the persistence of the DiI label. Embryos were incubated for 1 – 8 days post‐injection, fixed in 4% paraformaldehyde/0.25% glutaraldehyde and processed for cryostat sectioning. DiI‐labelled cells were readily identifiable in
culture and in sections of embryos at all stages examined. Several cell types were identified, based on their morphology and soma size. These included cells with large cell bodies and bright DiI‐labelling that appeared to be neurons and smaller, more weakly labelled cells that appeared non‐neuronal. The latter presumably had divided several times, accounting for their reduced levels of dye. Many of the DiI‐labelled cells were found in and around neural crest‐derived sympathetic ganglia, aortic plexuses and adrenomedullary cords, but were rarely observed
in dorsal root ganglia. The aldehyde fixative (Faglu mixture) used in this study reacts with catecholamines to form a bright reaction product in adrenergic cells including those in the sympathetic ganglia and the adrenal medulla. The catecholamine biproduct and the DiI in the
same cell can easily be viewed with different fluorescent filter sets. A variable number of the DiI‐labelled cells in these adrenergic sites contained catecholamines. Cells derived from younger 6 day ciliary ganglion dissociates exhibited detectable catecholamine neurotransmitters
earlier and more frequently than those derived from 8 day embryos. The presence of cells exhibiting both bright DiI and catecholamine fluorescence is consistent with previous indications that post‐mitotic ciliary ganglion neurons can undergo phenotypic conversion from cholinergic to adrenergic when transplanted to the trunk environment.
Deficits in Beam‐Walking After Neonatal Motor Cortical Lesions are not Spared by Fetal Cortical Transplants in Rats
Authors: Swenson R. S. , Danielsen E. H. , Klausen B. S. , Erlich E. , Zimmer J. , Castro A. J.
Published: March 2007

Adult rats that sustained unilateral motor cortical lesions at birth demonstrated deficits in traversing an elevated narrow beam. These deficits, manifested by hindlimb slips off the edge of the beam, were not spared in animals that received fetal cortical transplants into the lesion cavity immediately after lesion placement.
Fetal Medial Habenula Transplants: Innervation of the Rat Interpeduncular Nucleus
Authors: Lenn Nicholas J. , Seeley P. John , Field Pauline M. , Raisman Geoffrey
Published: March 2007

The effects of donor age and site of placement on the survival of fetal medial habenula (MH) transplants into adult rats hosts were examined. The innervation of the interpeduncular nucleus (IPN) in such cases was also examined. Explants of MH consisting of the medial‐dorsal lip of the third ventricle were held in vitro for 1—2 days. Colloidal gold conjugated to wheat germ agglutinin was added for the last 18 hours to label the cells. Four of 16 cases with E19 derived transplants contained donor neurons. Markedly larger transplants were present in 95% of 20 cases with E16 derived transplants. Sites in the ventral midbrain were successful, while limited or no survival occurred at sites more remote from IPN. Retrograde labeling of transplant neurons was present in each case studied with HRP injection into host IPN. Colloidal gold‐labeled macrophages, some oriented capillaries and GFAP‐positive processes marked the donor‐host interface. In EM the interface was evident only by the difference in tissue elements in the transplant versus host. Numerous synapses of Gray types I and II were present in the transplant. Excellent survival of MH neurons, donor/host interfaces, innervation of IPN by the transplant and fine structure in and around the transplants, all suggest that such preparations are suitable for further experimental analysis of the habenulo‐interpeduncular system.
Tectal Tissue Grafted to the Midbrain of Newborn Rats: Effect of Donor Age on the Survival, Growth and Connectivity of Transplants
Authors: Majda Bernadette T. , Harvey Alan R.
Published: March 2007

Tectal tissue from fetal (E15, E18, E20) and newborn (P0) rats was transplanted to the midbrain of newborn rats. Graft survival and size decreased with increasing donor age. Host retinal input was found in E15, E18 and E20 grafts; the specific pattern of retinal innervation was similar for all fetal donor ages.
Lesioning of the Striatum Reverses Motor Asymmetry in the6‐Hydroxydopamine Rodent Model of Parkinsonism
Authors: Friehs G. M. , Parker R. G. , He L. S. , Haines S. J. , Turner D. A. , Ebner T. J.
Published: March 2007

In the rat several paradigms of grafting of adrenal
medulla into the striatum were studied following the
induction of a parkinsonian model, using a unilateral
6‐hydroxydopamine (6‐OHDA) lesion of the substantia nigra
. Direct autologous grafting of adrenal medulla
into the caudate‐putamen complex, a radiofrequency
lesion of the striatum alone, and a radiofrequency
lesion followed by delayed grafting of adrenal medulla
were compared by analyzing rotational behavior.
Direct grafting of adrenal medulla produced an
overall reduction in apomorphine induced turning
behavior by 43.5% when compared with controls.
Radiofrequency lesioning of the striatum without
graft showed the best improvement over control
animals with a 92% reduction in the total number of
rotations induced by apomorphine. Delayed grafting
into the caudate lesion cavity also produced a
dramatic reduction in motor asymmetry but did not
improve the behavioral outcome over that of the
lesion alone. Animals receiving only radiofrequency
lesions exhibited a band of increased tyrosine
hydroxylase like immunoreactivity bordering the
lesion cavity. Graft survival was limited in the nonlesioned
animals but appeared enhanced in the
animals whose striatum was previously lesioned.
Lesion location within the striatum influenced the
behavioral outcome. Large reductions in
apomorphine‐induced rotations could result from
small lesions of the dorso‐lateral striatum. These
findings indicate that selective destruction of the
caudate‐putamen complex without tissue
transplantation produces a dramatic reduction in the
motor asymmetry of 6‐OHDA treated rats. Suggested
explanations for the decrease in induced rotational
behavior with radiofrequency lesions include a
decrease in the number of striatal dopamine
receptors following cell destruction and lesioninduced
recovery of host dopaminergic afferents.
Striatal damage in critical areas can reverse some of
the motor behavior associated with the 6‐OHDA
model and needs to be considered when evaluating
the effects of neural grafting in this model.
Autologous Adrenal Medullary, Fetal Mesencephalic, and Fetal Adrenal Brain Transplantation in Parkinson′s Disease: A Long‐Term Postoperative Follow‐Up
Authors: Madrazo Ignacio , Franco-Bourland Rebecca , Aguilera Maricarmen , Ostrosky-Solis Feggy , Madrazo Mario , Cuevas Carlos , Catrejon Hugo , Guizar-Zahagun Gabriel , Magallon Eduardo
Published: March 2007

We report on the clinical status of 5 patients with Parkinson′s disease (PD) 3 years after autologous adrenal medullary (AM)‐to‐caudate nucleus (CN) implanfion, and of 2 PD patients, 2 years after fetal ventral mesencephalon (VM)‐ and fetal adrenal (A)‐to‐CN homotransplantation. Current clinical evaluation of 4 of the AM grafted patients revealed sustained bilateral amelioration of their PD signs, most notably of rgidity, postural imbalance and gait disturbances, resulting in a substantial improvement in their quality of life. the disease‐related dystonia of one of them disappeared only 2 years after surgery. The levodopa requirements of 2 of these patients and the anticholinergic therapy of another have been reduced. In agreement with the satisfactory clinical evaluation of these 4 patients, their neuropsychological and electrophysiological improvements, initially registered 3 months after surgery, have been maintained for 3 years. After 1 year of significant recovery, the 5th patient of this group has almost returned to her preoperative state.

The 2 homotransplanted patients also showed sustained bilateral improvement of their PD signs. Two years after surgery, the most improved signs of the fetal VM case were rigidity, bradykinesia, postural imbalance, gait disturbances and facial expression. The fetal A case has only shown amelioration of rigidity and bradykinesia. Neither of them has shown significant neuropsychological changes. Their current levodopa requirements are less than before surgery.

The improvements shown here by PD patients after brain tissue grafts go beyond those obtained using any other therapeutic approach, when levodopa fails. Although more studies and the development of these procedures are obviously required, these initial human trials appear to be resisting the test of time.
New Surgical Approach To Overcome The Inability Of InjuredMammalian Axons To Grow Within Their Environment
Authors: Solomon Arieh , Lavie Vered , Ben-Bassat Sjana , Belkin Michael , Schwartz Michal
Published: March 2007

We present a new method for creating
conditions conducive to axonal growth in
injured optic nerves of adult rabbits. The
surgical approach consists of making a cavity in
the adult rabbit optic nerve, into which a piece of
nitrocellulose soaked with conditioned medium
originating from regenerating fish optic nerves
is implanted. In addition, daily irradiation (10
days, 5 min, 35 mW) with low energy He‐Ne
laser is carried out. Such a combined treatment
may open a door to neurobiologists and
clinicians, hoping to unravel the enigma of
mammalian CNS regeneration.
Is Phaseolus vulgaris Leucoagglutinin (PHA‐L) a Useful Markerfor Labeling Neural Grafts?
Authors: Kott J. N. , Westrum L. E. , Bhatia A. M.
Published: March 2007

The lectin Phaseolus vulgaris leucoagglutinin
(PHA‐L) has come into wide use as an anterograde
neuroanatomical tracer. The ability of this
lectin to fill entire neurons and remain in place
over long periods suggested it might be an ideal
marker for donor cells to be grafted into hosts
for long survival periods. We have used the lectin
PHA‐L to mark fetal rat olfactory bulb (OB)
cells prior to grafting into host rat OBs. Hosts
were sacrificed at various times up to 9 weeks after
grafting, and tissue was immunohistochemically
processed for PHA reactivity. After 2 and 4
weeks survival, sparse patterns of labeled cells
were observed within the host OBs. However, after
9 weeks survival, few if any labeled cells were
visible within host tissue. We conclude that
PHA‐L may be a less than satisfactory marker
for fetal rat cells (other than astrocytes) which
are to be identified in host tissue after a period of
several weeks.
Fetal Transplant‐Induced Restoration of Spatial Memory in Rats with Lesions of the Nucleus Basalis of Meynert
Authors: Santucci Anthony C. , Kanof Philip D. , Haroutunian Vahram
Published: March 2007

Bilateral lesions of the nucleus basalis of Meynert (nbM) in rats produced mnemonic deficits when subjects were tested on tests of spatial memory over a period of 3 to 7.5 months postoperatively. The transplantation of cholinergic‐rich, fetal ventral forebrain tissue to either two or four frontoparietal cortical sites normalized performance on the spatial memory tasks. However, which transplant condition yielded recovery depended upon the nature of the task and/or posttransplantation interval. When assessed 8 months following transplant surgery, cortical choline acetyltransferase and acetylcholinesterase activity levels in both transplant groups were comparable to those values found in sham‐operated animals. These data indicate that fetal transplants can reverse the mnemonic deficits and restore cortical cholinergic neurochemical activity to near‐normal levels in rats with nbM lesions.
An Evaluation of the Possible Protective Effects of Neonatal Striatal TransplantsAgainst Kainic Acid‐Induced Lesions
Authors: Nash David R. , Kaplan Stanley M. , Norman Andrew B. , Sanberg Paul R.
Published: March 2007

The present study examined the recent report
that transplantation of neonatal striatal tissue
into kainic acid (KA) lesioned striatum protected
the contralateral striatum from a subsequent KA
lesion. We did not find a significant difference in
the survival rate of animals that received
neonatal striatal transplants into a KA lesioned
striatum followed by a subsequent lesion of the
contralateral striatum compared to those
animals that received bilateral KA‐induced
striatal lesions alone. The tissue transplants did
not protect against the degeneration of striatal
neurons induced by KA. Indeed, the survival
rate was very low (25%) in the transplant groups.
A second experiment was also performed to
examine whether a neonatal striatal transplant
might reduce the severe syndrome of aphagia
and adipsia associated with KA lesions of the
striatum. Animals that received the neonatal
striatal transplants showed increased aphagia
and adipsia compared to animals only receiving
the KA lesion. Again, the transplant group had a
very low survival rate (10%). The present study
was unable to confirm that neonatal striatal
transplants protect against KA lesions either by
themselves or in conjunction with a recent KA
lesion.