bluuebunny/crossref_metadata_2025 huggingface dataset:
Transcatheter closure of postinfarction ventricular septal defects using the new Amplatzer muscular VSD occluder: Results of a U.S. Registry
Authors: Holzer Ralf , Balzer David , Amin Zahid , Ruiz Carlos E. , Feinstein Jeffrey , Bass John , Vance Michael , Cao Qi‐Ling , Hijazi Ziyad M.
Published: January 2004

The objective of this study was to assess the immediate and mid‐term results of transcatheter closure of postinfarct muscular ventricular septal defects (VSDs) using the new Amplatzer postinfarct muscular VSD device (PIMVSD). Ventricular septal rupture occurs in 0.2% of myocardial infarcts and remains associated with very high morbidity and mortality. Data were prospectively collected for 18 patients who underwent attempted device closure of postinfarction VSDs between 2000 and 2003. Five patients underwent the closure in the acute phase (within 6 days from the infarct); the remaining patients underwent closure on day 14–95 after the diagnosis of the infarct. Outcome parameters included procedural success, evidence of residual shunts on echocardiography, and occurrence of procedure‐related complications. The procedure was successful in deploying a device across the VSD in 16 of 18 patients. The 30‐day mortality was 28%. Eleven patients are still alive and have been followed up for a median of 332 days. Two patients required a second procedure to close a residual VSD. At the most recent outpatient follow‐up, the VSD was completely closed in two patients, six patients had a trivial or small residual shunt, and two patients had a moderate residual shunt. We conclude that percutaneous device closure of postinfarction VSDs using the Amplatzer PIMVSD occluder appears to be safe and effective. Further trials are required to assess long‐term efficacy and compare the results with those of surgical closure. Catheter Cardiovasc Interv 2004;61:196–201. © 2004 Wiley‐Liss, Inc.
Intracoronary brachytherapy, a promising treatment option for diabetic patients: Results from a European multicenter registry (RENO)
Authors: Naber Christoph K. , Baumgart Dietrich , Bonan Raoul , Wegscheider Karl , Serruys Patrick W. , Colombo Antonio , Silber Sigmund , Eeckhout Eric , Eggebrecht Holger , Erbel Raumund , Urban Philip
Published: January 2004

Despite advances in the interventional treatment of coronary disease, diabetics still have double the case fatality rate as nondiabetics. The purpose of this analysis from the Radiation in Europe With Novoste (RENO) registry was to assess the clinical and angiographic 6‐month outcome of diabetic patients in comparison to nondiabetic patients after localized β‐radiation. A total of 1,098 patients (83.8% with in‐stent restenosis) treated with the Novoste Beta‐Cath system in Europe were enrolled in the RENO registry. Diabetes was, irrespective of the type of lesion treated, no significant risk factor for major adverse cardiac events or target vessel revascularization. Individuals with diabetes (n = 256) and without diabetes (n = 833) displayed no significant differences concerning clinical or angiographic endpoints. Vascular brachytherapy appears to be the first technique to even out the increased risk of diabetic patients undergoing percutaneous coronary interventions in the routine clinical setting. Thus, intracoronary brachytherapy represents a promising treatment option for diabetic patients. Catheter Cardiovasc Interv 2004;61:173–178. © 2004 Wiley‐Liss, Inc.
Der Bär ist los: Chemie mit Gummibärchen
Authors: Full Roland
Published: January 2004

Das Gummibärchen birgt ein hohes Motivationspotenzial, das auch für im Chemieunterricht genutzt werden kann. Die beschriebenen Experimente wollen einen Beitrag dazu leisten, aus dem Objekt der Essbegierde ein Objekt der Wissbegierde zu machen. Die vorgestellte „Gummibärchen‐Chemie”︁ reicht von einfachen Untersuchungen zur Schwimmfähigkeit des Gummibärchens über Nachweisreaktionen seiner organischen Inhaltsstoffe bis hin zu Anwendungen aus der Bio‐ und Elektrochemie.
Kolloide: Die Welt der vernachlässigten Dimensionen
Authors: Hofmann Thilo
Published: January 2004

Aquatische Kolloide sind in allen natürlichen Gewässern vorhanden. Sie umfassen anorganische Kolloide wie Tonminerale, organische Kolloide wie Huminstoffe, Mikroorganismen und anthropogen eingetragene Kolloide wie Ruß oder Platin aus Katalysatoren. Kolloide können hydrophobe organische Schadstoffe sorbieren und transportieren oder nachteilig die Wasserqualität beeinflussen (z.B. pathogene Keime). Sie können die Leistung von Brunnen durch Verblockung der Porenräume im Grundwasser mindern. Kolloide können jedoch auch zur Sanierung von Grundwasserschadensfällen eingesetzt (Tenside) oder in der Wasseraufbereitung verwendet werden (Flockungsmittel, Katalysatoren). Kolloide entstehen oder werden mobilisiert durch Verwitterungsprozesse, Umsetzung organischer Substanzen, Auflösungs‐ und Fällungsprozesse sowie hydrochemische und hydraulische Veränderungen. Ihre Stabilität wird maßgeblich von den Oberflächeneigenschaften bestimmt. Viel versprechende neue analytische Techniken wie die Feld‐Fluss‐Fraktionierung, Laserinduzierte Breakdown‐Detektion oder Röntgenmikroskopie werden unser Verständnis von aquatischen Kolloiden in den kommenden Jahren erweitern.
Flüssigkristall‐Anzeigen
Authors: Borchard‐Tuch Claudia
Published: January 2004

Sichtbarer Ausdruck des elektronischen Zeitalters ist die fast überall anzutreffende digitale Anzeige von Daten und Bildern, und Displays sind die wichtigste und gleichzeitig auch teuerste Schnittstelle zwischen Mensch und Maschine. Allein im dritten Quartal 2003 wurden weltweit über 130 Millionen Handy‐Displays produziert.
Quecksilberentsorgung mit Bakterien
Authors: Jacoby Petra
Published: January 2004

In Zukunft könnten genmanipulierte Bakterien Abwässer von Quecksilberverbindungen reinigen. Die Mikroben wirken wie Mini‐Filter und sind in der Lage, große Mengen des toxischen Schwermetalls zu speichern.
Die Angst des Chemikers vor dem fugu
Authors: Roth Klaus
Published: January 2004

Das hochwirksame Gift des fugus faszinierte die Menschen schon seit Urzeiten. Erst 1964 gelang die Strukturaufklärung des Tetrodotoxin, das sich als eine chemisch ungewöhnliche Verbindung entpuppte. Das Gift ist ein unersetzliches Handwerkszeug bei Untersuchungen von neuronalen Prozessen, da Na+‐Kanäle hochselektiv blockiert werden können. Dass der fugu, trotz seiner Giftigkeit, seit Jahrhunderten von japanischen Gourmets als unvergleichliche Delikatesse geschätzt wird, mag uns Europäern unverständlich sein, erinnert uns aber daran, dass kulturelle Unterschiede reizvoll sind und mit Toleranz und Neugier begegnet werden sollten. Jedes Jahr findet in Shimonoseki eine Trauerfeier unter großer Beteiligung der Bevölkerung statt. Nicht wegen der menschlichen Opfer, sondern wegen der verstorbenen Fische. Shinto‐Priester beten für sie und geben eine größere Zahl gefangener fugus symbolisch als Dank an das Meer zurück.
Chemische Kampfstoffe
Authors: Hildebrandt Henry
Published: January 2004

Vergangenheitsbewältigung und aktuelle Aufgabe. Teil 2

Bis in die 1970er Jahre hinein war es weltweit üblich, ausrangierte Chemiewaffen im Meer zu versenken. Amerikaner und Russen kippten sie in der Ostsee oder im Atlantik über Bord, Briten entsorgten Nervengifte vor der irischen Küste. Italien wählte seine Adria, um die Reste seines chemischen Arsenals loszuwerden, das es im Äthiopienkrieg 1936 eingesetzt hatte.
Hsp90‐Blocker treffen Krebszellen zielsicher
Authors: Groß Michael
Published: January 2004

Hitzeschockproteine sind eine universell verbreitete Antwort der Zelle auf Hitzestress. Viele von ihnen dienen der Zelle als molekulare Chaperone, das heißt sie können andere Proteine vorübergehend an sich binden und vor der Entfaltung und Verklumpung zu unlöslichen Aggregaten schützen. Hsp90 ist ein Chaperon, dessen Funktion noch nicht vollständig aufgeklärt ist, das aber eine Schlüsselrolle im komplexen Netzwerk der zellulären Funktionen zu spielen scheint. Die von ihm behüteten Proteine sind oft wichtige Regulatoren, wie etwa Transkriptionsfaktoren oder Hormonrezeptoren.
Druck genügt
Authors: Groß Michael
Published: January 2004

Forscher am MIT haben eine neue Art von Zweikomponenten‐Kunststoff entwickelt, der sich schon bei Zimmertemperatur allein durch Druck in einen zähflüssigen Zustand versetzen und in neue Formen pressen lässt.

http://www.michaelgross.co.uk
COMSPIRA: A common approach to spiral and radial MRI
Authors: Rodríguez Ignacio , Pérez De Alejo Rigoberto , Cortijo Manuel , Ruiz‐Cabello Jesús
Published: January 2004

The choice of what type of k‐space coverage should be used depends on a given application and hardware limitations. So far, radial‐ and spiral‐collected data have physical analogies in terms of sequence design, although they have not been presented, to our best knowledge, under the same pulse sequence. A mathematical formulation behind the combination of these non‐Cartesian sampling methods under the same pulse sequence [(COMSPIRA) combined spiral and radial] is presented in this study. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 20B: 40–44, 2004.
Target field design for MAMBA step fields
Authors: Lee K.J. , Paley M.N.J. , Barber D.C. , Wilkinson I.D. , Griffiths P.D.
Published: January 2004

Multiple Acquisition with Micro‐B0 Array (MAMBA) is a class of parallel imaging techniques. Its distinguishing feature is the use of auxiliary coil arrays that introduce a stepped field within the B0 field. The steps form regions of uniform field, which then can be used to encode in one or more dimensions. The steps can also be used in conjunction with sensitivity encoding (SENSE) techniques to achieve higher acceleration factors. Step fields necessarily contain high‐order harmonics and require high currents to implement them. To reduce current demands, we have combined the pseudoinverse target field method with subset selection and Tikhonov regularization to derive coil array designs for some MAMBA configurations. We conclude that MAMBA will be most effective in long and narrow or thin and flat configurations. In these situations, our algorithm enables sparse designs with low current demands to be obtained. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 20B: 1–8, 2004.
Tissue‐equivalent phantoms for high frequencies
Authors: Beck B.L. , Jenkins K.A. , Rocca J.R. , Fitzsimmons J.R.
Published: January 2004

Saline phantoms have been used traditionally as biological mimics to load radio frequency (RF) coils during development and testing. However, the relative permittivity of biological tissues diverges from that of water as frequencies increase, resulting in saline phantoms loading coils much differently than the real biological systems. We have developed tissue‐equivalent phantoms with compartments containing gels that approach the relative permittivities and conductivities of a rat at 470 MHz. The gel characteristics are measured with a coaxial probe and the coil‐loading characteristics of the assembled phantoms are compared with real animals. It is shown that the tissue‐equivalent phantoms load coils similarly to live rats, unlike the saline phantoms. Using these tissue‐equivalent phantoms, the coil designer can be confident that when the coil leaves the laboratory to be used in the magnet, it will be optimized for the biological system of interest. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 20B: 30–33, 2004.
Design and implementation of a uniplanar gradient field coil for magnetic resonance imaging
Authors: Lemdiasov Rostislav , Ludwig Reinhold , Brevard Mat , Ferris Craig
Published: January 2004

A new approach to design uniplanar gradient coils for magnetic resonance imaging (MRI) is presented. The theoretical formulation involves a constraint cost function between the desired field in a particular region of interest in space and the current‐carrying coil plane based on Biot‐Savart's integral equation. An appropriate weight function in conjunction with linear approximation functions allows the transformation of the problem formulation into a linear matrix equation in which its iterative solution yields discrete current elements in terms of magnitude and direction within the prescribed coil plane. These current elements can be synthesized into an overall practical wire configuration by suitably adding individual wire loops. Numerical predictions and practical testing for aGygradient coil underscore the success of this approach in terms of achieving a highly linear field while maintaining low parasitic fields. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 20B: 17–29, 2004
Real‐time modulation of acoustic gradient noise in interventional MRI
Authors: Moelker Adriaan , Vogel Mika W. , Pattynama Peter M.T.
Published: January 2004

Acoustic noise is inherent to magnet resonance imaging (MRI) and poses safety risks to patients and interventional radiologists. Although a spectrum of noise reduction techniques has been implemented, new developments further increase sound levels. Silent pulse sequences based on derating gradient currents have been proposed but are limited to slow pulse sequences not suitable for interventional MRI (iMRI). However, iMRI does not continuously require fast imaging with high image update rates. Therefore, the aim of this study was to develop a tool that could remotely derate the gradient currents in real time, operated by the interventionalist. The duration of the derated gradients is increased to retain image resolution [this extends imaging time and echo time (TE)]. The experiment setup consisted of a custom‐built remote controller located in the interventional MR room. A fast spoiled gradient recalled echo (FSPGR) sequence was tested and acoustic recordings were made with a microphone in the magnet bore. An optical link sent data from the remote controller to a computer that was connected to a 1.5‐T cardiovascular MR scanner over ethernet. A software server installed on the MR system received the requests and passed these on to the integrated pulse generator in order to control the real‐time imaging. Slew rate adjustments were accomplished by calculating instruction period changes and adjusted waveform amplitudes accordingly. The experimental setup reduced the slew rate up to 16‐fold, which resulted in a considerable acoustic noise reduction of 21.1 dBA. The remote controller performed well and image quality showed no substantial qualitative changes. We made use of the previously described idea of silent pulse sequence designing. Although derating is at the expense of the image refresh rate, our real‐time slew rate reduction is compatible with the fact that iMRI procedures do not continuously require fast image update rates. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 20B: 34–39, 2004.
Connexin35/36 gap junction proteins are expressed in photoreceptors of the tiger salamander retina
Authors: Zhang Jian , Wu Samuel M.
Published: January 2004

Photoreceptors in the vertebrate retina are electrically coupled with one another. Such coupling plays important roles in visual information processing. Physiological properties of rod‐rod and rod‐cone coupling have been best studied in the salamander retina, yet the cellular and molecular basis of these electrical synapses has not been established. Recently, connexin35/36 (Cx35/36) gap junction proteins were found to be highly expressed in brain and retina, suggesting that it may mediate photoreceptor coupling. To test this idea, we examined the cellular distribution of Cx35/36 in the salamander retina. Western blot analysis showed the expression of Cx35/36 proteins, and confocal microscopy revealed characteristic punctate Cx35/36 immunoreactivity in both synaptic layers. In addition, Cx35/36‐positive plaques were detected in the outer nuclear layer (ONL) between neighboring rods, and these plaques outlined the mosaic of the rod network at a level distal to the external limiting membrane. Moreover, although Cx35/36 plaques were detected between some cones and their adjacent rods, the number and size of these plaques was smaller, and their staining intensity was diminished compared with the plaques between adjacent rods. Furthermore, Lucifer yellow injection together with confocal microscopy revealed that Cx35/36‐puncta were colocalized with finlike structures of rod cell membrane, with the ultrastructure of gap junctions between paired rod fins having been found by electron microscopy. Therefore, our findings demonstrate that Cx35/36 expression in photoreceptors is primarily located between rods and to a lesser extent between rods and cones, suggesting that Cx35/36 may participate in electrical coupling between rods and between rods and cones in the salamander retina. J. Comp. Neurol. 470:1–12, 2004. © 2004 Wiley‐Liss, Inc.
Bromodeoxyuridine administered during neurogenesis of the projection neurons causes cerebellar defects in rat
Authors: Sekerková Gabriella , Ilijic Ema , Mugnaini Enrico
Published: January 2004

Bromodeoxyuridine (BrdU) is broadly used in neuroscience to study embryonic development and adult neurogenesis. The potential toxicity of this halogenated pyrimidine analogue is frequently neglected. In this study, we administered BrdU in small doses by the progressively delayed cumulative labeling method to immunocytochemically tag different cerebellar cell types with antibodies to specific markers and BrdU in the same section. The well‐known structure of the cerebellum made it possible to ascertain several toxic effects of the treatment. Time‐pregnant rats were given five or six injections of 5 or 6 mg of BrdU (∼12–20 mg/kg) at 8‐hour intervals over 2 successive days between day 11 and 21 of pregnancy (E11–E12 to E20–E21), and the adult progeny was processed by immunocytochemistry. We demonstrate that this treatment effectively labeled distinct cerebellar cell populations but produced striking defects in the proliferation, migration, and settling of the Purkinje cells; reduced the size of the cerebellar cortex and nuclei; produced defects in the patterning of foliation; and also affected litter size, body weight, and mortality of the offspring. The observed toxic effects were consistent within individual treatment groups but varied between different treatment groups. Treatment with BrdU at the peak of neurogenesis of cerebellar projection neurons (E14) produced the most severe malformations. We observed no overt effects on the timing of neurogenesis for cerebellar neurons and glia across experimental groups. In conclusion, BrdU is a useful tool to study neural development, but its cytotoxicity represents a serious pitfall particularly when multiple doses are used to label cells. J. Comp. Neurol. 470:221–239, 2004. © 2004 Wiley‐Liss, Inc.
Altered epithelial density and expansion of bulbar projections of a discrete HSP70 immunoreactive subpopulation of rat olfactory receptor neurons in reconstituting olfactory epithelium following exposure to methyl bromide
Authors: McMillan Carr Virginia , Ring George , Youngentob Steven L. , Schwob James E. , Farbman Albert I.
Published: January 2004

A previously described subpopulation of rat olfactory receptor neurons, the 2A4(+)ORNs, is 1) distinguished by intense constitutive cytoplasmic immunoreactivity to antibodies to the 70‐kD heat shock protein (HSP70); 2) occurs sparsely but consistently through ventral and lateral olfactory epithelium (OE); and 3) projects to just two to three consistently located glomeruli in each olfactory bulb (OB) (Carr et al. [1994] J Comp Neurol 348:150–160). Immunoreactivity appears not to be stress‐related. To examine the persistence of these features following destruction and reconstitution of the OE, rats were subjected to methyl bromide‐induced OE lesion (Schwob et al. [1995] J Comp Neurol 59:15–37; Schwob et al. [1999] J Comp Neurol 412:439–457] and their OE and OBs examined with antibodies to HSP70 6–10.5 weeks postlesion. Lesioned OE showed significantly increased 2A4(+)ORN densities but no alteration of 2A4(+)ORN zonal distribution. The OBs of lesioned animals showed marked expansions of 2A4(+)ORN bulbar projections, with 2–15‐fold increases in numbers of glomeruli showing 2A4(+)axons, and projection expansions were greater in animals maintained on chronic food restriction prior to lesioning. Examination of archival 5‐month post‐MeBr lesion material indicates that altered projection patterns are maintained. J. Comp. Neurol. 469:475–493, 2004. © 2004 Wiley‐Liss, Inc.
Distribution of corticotropin‐releasing factor‐immunoreactive neurons in the central nervous system of the domestic chicken and Japanese quail
Authors: Richard Sabine , Martínez‐García Fernando , Lanuza Enrique , Davies D. Ceri
Published: January 2004

In birds, as in mammals, corticotropin‐releasing factor (CRF) is present in a number of extrahypothalamic brain regions, indicating that CRF may play a role in physiological and behavioral responses other than the control of adrenocorticotropin hormone release by the pituitary. To provide a foundation for investigation of the roles of CRF in the control of avian behavior, the distribution of CRF immunoreactivity was determined throughout the central nervous system of the domestic chicken (Gallus domesticus) and Japanese quail (Coturnix japonica). The distribution of CRF‐immunoreactive (‐ir) perikarya and fibers in the chicken and quail brain was found to be more extensive than previously reported, notably in the telencephalon. Numerous CRF‐ir perikarya and fibers were present in the hyperstriatum, hippocampus, neostriatum, lobus parolfactorius, and archistriatum, as well as in the nucleus taeniae, nucleus accumbens, and bed nucleus of the stria terminalis, which exhibited the strongest immunolabeling in the telencephalon. The presence of dense populations of CRF‐ir perikarya in the medial lobus parolfactorius, nucleus of the stria terminalis, and paleostriatum ventrale, apparently giving rise to CRF‐ir projections to the mesencephalic reticular formation, the parabrachial/pericerulear region, and the dorsal vagal complex, suggests that these telencephalic areas may constitute part of the avian “central extended amygdala.” These results have important implications for understanding the role of extrahypothalamic CRF systems in emotional responses in birds. J. Comp. Neurol. 469:559–580, 2004. © 2004 Wiley‐Liss, Inc.
Synaptic connectivity of the diffuse bipolar cell type DB6 in the inner plexiform layer of primate retina
Authors: Jusuf Patricia R. , Lee Sammy C.S. , Grünert Ulrike
Published: January 2004

Diffuse bipolar cells in primate retina receive synaptic input from multiple cones and provide output to ganglion cells. Diffuse bipolar cells can be subdivided into six types (DB1–DB6) according to the stratification of their axon terminals in the inner plexiform layer, but their synaptic connectivity in the inner plexiform layer is not well understood. Here the stratification and synaptic connectivity of DB6 axon terminals were studied in the retinae of New World (marmoset) and Old World (macaque) monkeys. Immunohistochemical markers were applied to retinal sections. The sections were analyzed by confocal and deconvolution light microscopy as well as electron microscopy. The DB6 cells were identified with antibodies against CD15; rod bipolar cells were identified with antibodies against protein kinase Cα (PKCα); and AII amacrine cells were identified with antibodies against calretinin. The axons of DB6 and rod bipolar cells occupy distinct regions in stratum 5 of the inner plexiform layer. The distal processes of calretinin‐labeled AII cells are usually closely associated with rod bipolar axons but sometimes also with DB6 axons. Pre‐embedding immunoelectron microscopy showed that the vast majority (over 86%) of the synaptic output of DB6 cells is onto amacrine cell processes, whereas less than 14% goes to ganglion cell processes. In double‐labeled preparations DB6 axons occasionally made output onto calretinin‐labeled amacrine processes. Thus it is possible that AII cells receive some input from DB6 cells. J. Comp. Neurol. 469:494–506, 2004. © 2004 Wiley‐Liss, Inc.
Effects of two years of estrogen loss or replacement on nucleus basalis cholinergic neurons and cholinergic fibers to the dorsolateral prefrontal and inferior parietal cortex of monkeys
Authors: Tinkler Gregory Paul , Tobin Joseph Raphael , Voytko Mary Lou
Published: January 2004

The present study examined the long‐term (2 years) effects of estrogen loss or estrogen replacement therapy (ERT) on cholinergic neurons in the nucleus basalis of Meynert and on cholinergic fibers in the prefrontal and parietal cortex of adult female cynomolgus monkeys. Cholinergic fiber density in layer II of the prefrontal cortex was decreased in monkeys who were ovariectomized and treated with placebo for 2 years. In contrast, ovariectomized monkeys receiving ERT for 2 years had fiber densities that were comparable to those of intact controls. No differences in parietal cholinergic fiber density or nucleus basalis cholinergic neuron number or volume were found among intact, ovariectomized, or ERT monkeys. Our results suggest that ERT is effective in preventing region‐specific changes in cortical cholinergic fibers that result from the loss of circulating ovarian hormones. These modest but appreciable effects on cholinergic neurobiology following long‐term estrogen loss and ERT may contribute to changes in visuospatial attention function that is mediated by the prefrontal cortex. J. Comp. Neurol. 469:507–521, 2004. © 2004 Wiley‐Liss, Inc.
Expression of androgen receptor mRNA in zebra finch song system: Developmental regulation by estrogen
Authors: Kim Yong‐Hwan , Perlman William R. , Arnold Arthur P.
Published: January 2004

By using improved methods for in situ hybridization to detect expression of androgen receptor (AR) mRNA, the distribution of expression was mapped in the adult male zebra finch brain. In the neural song circuit, robust expression was found in area X of the lobus parolfactorius (LPO) as well as in other song regions previously reported. Expression was also found in many areas of the hypothalamus and dorsal thalamic nuclei, nucleus intercollicularis and ventricular areas of the midbrain, cerebellar Purkinje and granule cells, the hyperstriatum, medial neostriatum, medial LPO, and archistriatum. In juvenile males, AR mRNA expression was first detected in nucleus high vocal center (HVC) at posthatch day 9 (P9), in area X at P9–P11, and in the region of the robust nucleus (RA) in the medial archistriatum by P7. Estrogen treatment of hatchling females caused an increase in the expression of AR mRNA in HVC and area X by P11, whereas treatment of hatchling males with the aromatase inhibitor fadrozole decreased the expression of AR mRNA at P11. The present results indicate that masculine development of AR expression begins in area X and HVC before they are thought to be synaptically connected, suggesting that different song nuclei initiate sexual differentiation independently of transsynaptic masculinizing influences. The present results suggest that estrogen is necessary for full masculine AR expression in the song system and that the estrogenic regulation of AR contributes to subsequent differential actions of androgen in male and female song nuclei. J. Comp. Neurol. 469:535–547, 2004. © 2004 Wiley‐Liss, Inc.
Morphology and connections of the abdominal accessory neurons of the crayfish Cherax destructor
Authors: Drummond Joanne M. , Macmillan David L.
Published: January 2004

Associated with the abdominal muscle receptor organs of crayfish are accessory neurons that inhibit the activity of the stretch receptors. Cobalt infusion into their cut axons reveals four accessory somata associated with each hemiganglion in the abdomen of the crayfish Cherax destructor. These conform to the pattern described previously for these neurons: The cell bodies are in the ganglion posterior to the one from which they exit. We recorded intracellularly from the largest accessory neurons, Acc‐1 and Acc‐2, and stained them with intracellular dye to establish unambiguously the characteristics defining their identity and structure. We describe their branching patterns in the ganglion of origin and the ganglion of exit. This morphological information permitted us to distinguish all four accessory neurons in preparations with dye infused through their cut axons, and we propose a revised, unambiguous nomenclature for the two smaller ones. Our intracelluar recordings allowed us to reexamine the physiological relationships of Acc‐1 and Acc‐2, the only accessory neurons for which there are data in the literature. In general, the connections and inputs described in previous studies were substantiated, although there has clearly been confusion between the two, and they differ in a number of significant ways. We found that they are seldom active together, have different firing patterns, and may operate with different clusters of extensor and flexor motorneurons. The results illustrate the level at which the accessory neurons operate within the abdominal control system but do not distinguish between competing hypotheses concerning their role in behavior. The data are consistent with the view that accessory neurons assist in timing between adjacent segments. J. Comp. Neurol. 469:548–558, 2004. © 2004 Wiley‐Liss, Inc.
Presynaptic N‐methyl‐D‐aspartate receptor expression is increased by estrogen in an aromatase‐rich area of the songbird hippocampus
Authors: Saldanha Colin J. , Schlinger Barney A. , Micevych Paul E. , Horvath Tamas L.
Published: January 2004

The vertebrate hippocampus (HP) is sensitive to estrogens, in part via effects on N‐methyl‐D‐aspartate (NMDA)‐type glutamate receptors (NR). Although the precise mechanism of this interaction is unclear, it constitutes a key interface in the plasticity of the adult vertebrate HP. The songbird HP expresses high levels of aromatase (estrogen synthase), suggesting that locally generated steroid may affect excitatory pathways. By using light, confocal, and electron microscopy with antibodies that specifically recognize aromatase and NR, we have 1) mapped their distribution in the zebra finch brain, 2) documented their coexpression in HP neurons, 3) studied the ultrastructure of NR‐expressing cells in the HP, and 4) tested the influence of estrogen on the cellular and subcellular characteristics of NR‐positive HP neurons. Aromatase and NR are coexpressed in HP neurons. NRs are detectable in presynaptic boutons of the songbird HP in addition to postsynaptic loci. Treatment with estrogen increased the somal size and innervation of NR‐positive neurons and the frequency of presynaptic NR. Autoreception of excitatory neurotransmission via presynaptic NR may promote the strengthening of activity‐dependent, excitatory synapses, thereby enhancing learning. NR‐mediated autoreception may underlie estrogenic enhancement of HP structural and functional plasticity. J. Comp. Neurol. 469:522–534, 2004. © 2004 Wiley‐Liss, Inc.
Activity‐dependent regulation of the potassium channel subunits Kv1.1 and Kv3.1
Authors: Lu Yong , Monsivais Pablo , Tempel Bruce L. , Rubel Edwin W
Published: January 2004

Afferent activity, especially in young animals, can have profound influences on postsynaptic neuronal structure, function and metabolic processes. Most studies evaluating activity regulation of cellular components have examined the expression of ubiquitous cellular proteins as opposed to molecules that are specialized in the neurons of interest. Here we consider the regulation of two proteins (voltage‐gated potassium channel subunits Kv1.1 and Kv3.1) that auditory brainstem neurons in birds and mammals express at uniquely high levels. Unilateral removal of the avian cochlea leads to rapid and dramatic reduction in the expression of both proteins in the nucleus magnocellularis (NM; a division of the avian cochlear nucleus) neurons as detected by immunocytochemistry. Uniform downregulation of Kv1.1 was reliable by 3 hours after cochlea removal, was sustained through 96 hours, and returned to control levels in the surviving neurons by 2 weeks. The activity‐dependent changes in Kv3.1 appear to be bimodal and are more transient, being observed at 3 hours after cochlea removal and recovering to control levels within 24 hours. We also explored the functional properties of Kv1.1 in NM neurons deprived of auditory input for 24 hours by whole‐cell recordings. Low‐threshold potassium currents in deprived NM neurons were not significantly different from control neurons in their amplitude or sensitivity to dendrotoxin‐I, a selective K+ channel antagonist. We conclude that the highly specialized abundant expression of Kv1.1 and 3.1 channel subunits is not permanently regulated by synaptic activity and that changes in overall protein levels do not predict membrane pools. J. Comp. Neurol. 470:93–106, 2004. © 2004 Wiley‐Liss, Inc.
Alterations in calretinin immunostaining in the ferret superior olivary complex after cochlear ablation
Authors: Alvarado Juan Carlos , Fuentes‐Santamaria Verónica , Henkel Craig K. , Brunso‐Bechtold Judy K.
Published: January 2004

In this study, we used image analysis to assess changes in calretinin immunoreactivity in the lateral (LSO) and medial (MSO) superior olivary nuclei in ferrets 2 months after unilateral cochlear ablations at 30–40 days of age, soon after hearing onset. These two nuclei are the first significant sites of binaural convergence in the ascending auditory system, and both receive direct projections from the deafferented cochlear nucleus. Cochlear ablation results in a decrease in the overall level of calretinin immunostaining within the LSO ipsilaterally compared with the contralateral side and with control animals and within the MSO bilaterally compared with control ferrets. In addition, the level of calretinin immunostaining ipsilaterally within neurons in the LSO was significantly less in cochlear ablated than control animals. In contrast, there was no effect of cochlear ablation on the level of calretinin immunostaining within neurons either in the contralateral LSO or in the MSO. These results are consistent with a downregulation in calretinin within the neuropil of MSO bilaterally and LSO ipsilaterally, as well as a downregulation in calretinin within somata in the ipsilateral LSO as a result of unilateral cochlear ablation soon after hearing onset. Thus, cochlear‐driven activity appears to affect calcium binding protein levels in both neuropil and neurons within the superior olivary complex. J. Comp. Neurol. 470:63–79, 2004. © 2004 Wiley‐Liss, Inc.
Response of olfactory ensheathing cells to the degeneration and regeneration of the peripheral olfactory system and the involvement of the neuregulins
Authors: Williams Sarah K. , Franklin Robin J.M. , Barnett Susan C.
Published: January 2004

In this study we examined the proliferative response of olfactory ensheathing cells (OECs) to olfactory receptor neuron injury induced by zinc sulfate (ZnSO4) irrigation and related the response of OECs within the peripheral system to the inflammatory response induced by injury and the expression profile of neuregulins. After ZnSO4 treatment, degeneration in the epithelium is reproducible and rapid, with regeneration following after 4 days, and is morphologically complete by 5 weeks. Changes in the olfactory bulb are less dramatic, although degeneration of both the outer and the glomerular layers occurred. Treatment also induced a marked inflammatory response in both the epithelium and the bulb. Unlike Schwann cell changes associated with Wallerian degeneration, OECs did not proliferate or obviously migrate within the olfactory system in response to axonal loss, suggesting that the new nerves generated from the epithelium regrow back through conduits already formed by the glia. Expression of neuregulin 1α was maintained in the nerve by OECs, and changes in neuregulin 1 mRNA and erbB2 mRNA expression were detected, indicating that these growth factors may play a role in the regeneration of the peripheral olfactory system but not in OEC proliferation. J. Comp. Neurol. 470:50–62, 2004. © 2004 Wiley‐Liss, Inc.
Characterization of neuropeptide Y Y2 and Y5 receptor expression in the mouse hypothalamus
Authors: Fetissov Sergueï O. , Byrne Leah C. , Hassani Hessameh , Ernfors Patrik , Hökfelt Tomas
Published: January 2004

Neuropeptide Y (NPY) neurons abundantly innervate the hypothalamus, where NPY is involved in the regulation of a broad range of homeostatic functions. In the present work we studied NPY Y2 and Y5 receptor (R) gene expression in the mouse hypothalamus by using immunohistochemical detection of β‐galactosidase (β‐gal), a gene reporter molecule for Y2R and Y5R in Y2R‐knockout (KO) and Y5R‐KO mice, respectively. With this approach, cells normally expressing Y2R or Y5R are immunopositive for β‐gal. In the hypothalamus of the Y2R‐KO mouse, β‐gal immunoreactivity (‐ir) was found in numerous neurons of the medial preoptic nucleus as well as in the lateral anterior, periventricular, dorsomedial, tuberal, perifornical, and arcuate nuclei. Most of the dopaminergic neurons in the A13 dorsal hypothalamic group were β‐gal positive, whereas other hypothalamic dopaminergic neurons rarely displayed β‐gal‐ir. In the arcuate nucleus, most of the β‐gal‐positive neurons expressed NPY, but colocalizations with β‐endorphin were also found; in the tuberal and perifornical nuclei, many β‐gal‐positive neurons contained nitric oxide synthase. β‐Gal‐ir was also found in other forebrain regions of the Y2R‐KO mouse, including the amygdala, thalamic nuclei, hippocampal CA3 area, and cortex. In the hypothalamus of the Y5R‐KO mouse, β‐gal‐positive neurons were found mainly in the arcuate nucleus and contained β‐endorphin. The present data show that Y2R and Y5R are expressed in distinct groups of hypothalamic neurons. High levels of Y2R expression in the preoptic nuclei suggest an involvement of Y2R in the regulation of reproductive behavior, whereas Y2R expression in the arcuate, dorsomedial, and perifornical nuclei may be relevant to feeding and body weight control. The finding that A13 dopaminergic neurons express Y2R suggests a new mechanism putatively involved in the central control of feeding, in which NPY can modulate dopamine secretion. The distribution of Y5R expression supports earlier evidence for involvement of this receptor in control of feeding and body weight via NPY's action on proopiomelanocortin‐expressing neurons. J. Comp. Neurol. 470:256–265, 2004. © 2004 Wiley‐Liss, Inc.
Fos expression in otolith‐related brainstem neurons of postnatal rats following off‐vertical axis rotation
Authors: Lai Chun‐Hong , Tse Yiu‐Chung , Shum Daisy K.Y. , Yung Ken K.L. , Chan Ying‐Shing
Published: January 2004

To determine the critical time of responsiveness of developing otolith organ‐related brainstem neurons and their distribution, Fos protein expression in response to off‐vertical axis rotations (OVAR) was mapped in conscious Sprague Dawley rats from P5 to adulthood. OVAR was used to activate sequentially all utricular hair cells per 360° revolution. We detected the coding of horizontal head positions in otolith organ‐related neurons within the vestibular nucleus as early as P7. In the vestibular nuclear complex and its subgroups, the density of Fos‐immunoreactive (Fos‐ir) neurons increased steadily with age and reached the adult level by P21. In both labyrinthectomized rats subjected to OVAR and normal rats kept stationary, labeled neurons were found sporadically in the aforementioned brain regions in each age group, confirming that Fos labeling observed in neurons of normal experimental rats subjected to OVAR was due to otolith organ stimulation. Whereas OVAR‐induced Fos‐ir neurons were also first observed in vestibular‐related brain areas, such as the prepositus hypoglossal nucleus, gigantocellular reticular nucleus, and locus coeruleus, of normal experimental rats at P7, those in the inferior olive were observed only from P14 onward. This indicates the unique maturation time of inferior olivary neurons in gravity‐related spatial coding. In general, age‐dependent increase in OVAR‐induced Fos‐ir neurons was observed in brain areas that received otolith inputs. The locus coeruleus was exceptional in that prominent OVAR‐induced Fos‐ir neuronal number did not change with maturation, and this was well above the low but significant number of Fos‐ir neurons in control preparations. Taken together, our results suggest that neuronal subpopulations within the developing network of the horizontal otolith system provide an anatomical basis for the postnatal development of otolith organ‐related sensorimotor functions. J. Comp. Neurol. 470:282–296, 2004. © 2004 Wiley‐Liss, Inc.
In vitro analysis of mechanisms underlying age‐dependent failure of axon regeneration
Authors: Hafidi Aziz , Grumet Martin , Sanes Dan H.
Published: January 2004

Severed axons of the inferior colliculus (IC) commissure can regenerate across a lesion in organotypic cultures from postnatal day (P) 6 gerbils, but this regenerative capacity is lost by P12 (Hafidi et al. [ 1995] J Neurosci 15:1298–1307, [1999] J Neurobiol 41:267–280). In the present study, we examined the mechanisms underlying this age‐dependent failure of axons to regenerate. In P6–P12 heterochronic cultures, the P12 axons failed to cross the lesion site and project to the contralateral P6 IC lobe. In contrast, axons originating from the P6 lobe could regenerate through the lesion and invade the contralateral P12 IC lobe. To determine whether this age‐dependent change in regenerative capacity can develop in organotypic cultures, IC slices with an intact commissure were obtained from P6 animals, grown in vitro for 6 days, and then lesioned at the commissure. In these slices, axon regeneration failure was similar to that observed in normal P12 tissue. Several in vitro treatments enhanced axon regeneration: removal of the entire midline region, inhibition of protein synthesis at the lesion site, and exposure to ABC chondroitinase. Furthermore, when the injured commissural axons were provided with a carpet of C6‐R cells (a radial glia‐like cell line), significantly more axons projected to the contralateral lobe of the IC. Taken together, these results suggest that the maturation of nonneuronal cells within the lesion site lead to failed axon regeneration in mature animals, and show that ameliorative strategies can be evaluated in vitro. J. Comp. Neurol. 470:80–92, 2004. © 2004 Wiley‐Liss, Inc.
Characterization of synaptogyrin 3 as a new synaptic vesicle protein
Authors: Belizaire Roger , Komanduri Cheryl , Wooten Kerry , Chen Ming , Thaller Christina , Janz Roger
Published: January 2004

Synaptogyrins comprise a family of tyrosine‐phosphorylated proteins with two neuronal (synaptogyrins 1 and 3) and one ubiquitous (cellugyrin) isoform. Previous studies have indicated that synaptogyrins are involved in the regulation of neurotransmitter release. Synaptogyrin 1 is a synaptic vesicle protein; cellugyrin, by contrast, is absent from synaptic vesicles. In an effort to further characterize the synaptogyrin family, we studied the distribution of the synaptogyrin 3 protein in the nervous system. Subcellular fractionation and immunoprecipitation of synaptic vesicles from mouse brain showed that synaptogyrin 3 is associated with synaptic vesicles and that synaptogyrins 1 and 3 can reside on the same synaptic vesicle. Immunofluorescent staining of cultured hippocampal neurons confirmed the synaptic localization of synaptogyrin 3. Analysis of the relative distributions of synaptogyrins 1 and 3 in mouse brain revealed a more restricted expression pattern for synaptogyrin 3 compared to the ubiquitous distribution of synaptogyrin 1. Strong synaptogyrin 3 labeling was observed in the mossy fiber region of the hippocampus, substantia nigra pars reticulata, pallidum, and deep cerebellar nuclei. By comparison, the striatum and reticular and ventral posterolateral thalamic nuclei, which all showed synaptogyrin 1 labeling, contained significantly less synaptogyrin 3. Finally, we used in situ hybridization experiments to correlate synaptogyrin 3 mRNA in cell bodies with synaptogyrin 3 protein at synapses. Altogether, our data indicate that neuronal synaptogyrins are differentially expressed protein isoforms that may represent functionally distinct populations of synapses and/or synaptic vesicles. J. Comp. Neurol. 470:266–281, 2004. © 2004 Wiley‐Liss, Inc.
Re‐evaluation of the afferent connections of the pituitary in the weakly electric fish Apteronotus leptorhynchus: An in vitro tract‐tracing study
Authors: Corrêa Sônia A.L.
Published: January 2004

The pituitary plays a key role in the interaction between the brain and the endocrine system. We re‐examined the afferent connections of the pituitary in the weakly electric fish Apteronotus leptorhynchus using the in vitro application of dextran‐tetramethylrhodamine to the pituitary. The resultant retrograde labeling was analyzed. Application of the tracer to the rostral part, but not the caudal part, of the pituitary labels hypothalamic cells in the anterior division of the periventricular nucleus, the suprachiasmatic nucleus, and the nucleus tuberis lateralis pars anterior. Application of the tracer to either the rostral or caudal parts of the pituitary labels hypothalamic cells in the posterior division of the periventricular nucleus (RPPp), the nucleus hypothalamus caudalis (Hc), the nucleus hypothalamus anterioris, the ventral hypothalamic nucleus, and the central nucleus of the inferior lobe. Furthermore, cells in the rostral two‐thirds of the brainstem reticular formation (RF) project to the entire rostrocaudal extent of the pituitary. The largest projections to the pituitary are from Hc, PPp, and RF. Of the cells in Hc that project to the pituitary, almost all (96%) are small and the remainder are medium‐sized. Of the cells in PPp that project to the pituitary, about half are small or medium‐sized (44% and 56%, respectively). In Hc and PPp, about one‐third to one‐half of the cells that project to the pituitary are markedly elongated. The cells in RF that project to the pituitary are small (4%), medium‐sized (89%), or large (7%) and about four‐fifths of these cells are markedly elongated. With regard to the RF projections, the pituitary may receive copies of motor instructions and sensory information supplied by collaterals of the descending and ascending projection systems of RF cells. Thus, the ongoing motor activity of the animal and the ensuing sensory feedback from this activity could directly influence the pituitary. J. Comp. Neurol. 470:39–49, 2004. © 2004 Wiley‐Liss, Inc.