bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photochemical formation of silver‐gold (AgAu) composite colloids in solutions containing sodium alginate
Authors: Sato Tomoo , Kuroda Shigeru , Takami Akinori , Yonezawa Yoshiro , Hada Hiroshi 
Published: December 2004

AbstractPhotochemical formation of colloidal silver, colloidal gold and silver‐gold (Ag‐Au) composite colloids under mild conditions has been studied. Irradiation of either aqueous AgCIO4 or HAuCI4 solution in the presence of sodium alginate (SA) with 253.7 nm light yielded colloidal silver or gold, whose particle diamter was 10‐30 nm or 40‐60 nm, respectively. The Ag‐Au composite colloids consisting of mixtures of silver and gold domains (particle diameter 30‐150 nm) have been prepared and their extinction spectra have been examined on the basis of a conventional Mie theory in combination with an effective medium theory to estimate the optical constants of these colloids. It has been shown that the extinction spectra of the Ag‐Au composite colloids are completely different from those of Ag‐Au alloy colloids, in that the former have two extinction maxima close to the colloidal extinction bands of pure silver and gold, in contrast to a single extinction maximum of the latter. The importance of natural, high‐molecular carboxylic acids such as alginic acid in the photochemical formation of metal colloids and thin films has been stressed.
Evaluation of extraction techniques for butyltin compounds in sediment
Authors: Zhang Shuzhen , Chau Y K , Li W C , Chau A S Y 
Published: December 2004

AbstractThere have been many methods available for the determination of butyltin compounds in sediment. The variations of these methods are not in the methods of determination but rather in the extraction of these compounds from the complex matrices. All of these methods have not been critically compared or evaluated, mainly because of the lack of a suitable reference sediment for butyltin compounds.Recently, the National Research Council of Canada has introduced a reference sediment (PACS‐1) which contains certified values of butyltin compounds. The present study compares the recoveries of ten extraction techniques for butyltin species using ethylation derivatization and GC AA as the method of determination. Of these ten methods, only four were found satisfactory for extraction of the dibutyltin and tributyltin species. None of the methods evaluated, however, could quantitatively extract monobutyltin from sediment.
Crystal and molecular structures of tris (p‐methoxyphenyl)‐ and tris(2,4, 6‐trimethylphenyl)tin(IV) acetates
Authors: Wharf I , Simard M G 
Published: December 2004

AbstractThe crystal and molecular structures of tris(p‐anisyl)tin acetate (1) (p‐anisyl = p‐methoxyphenyl) and trimesityltin acetate (2) (mesityl = 2,4,6‐trimethylphenyl) have been determined. Both have monomeric structures with the acetate group acting as an asymmetric bidentate ligand. Bond valence analysis of (1) and (2) and other Ph3SnO2CR suggest however that the carboxylate ligand effectively occupies a single bonding position at tin. Thus in (1) and (2) the tin atom is in a chemical environment equivalent to that found in four‐coordinate R3Sn‐X systems based on tetrahedral geometry.
Dimerization of aldehydes to carboxylic esters catalyzed by K2[Fe(CO)4]–crown ether system
Authors: Yamashita Masakazu , Ohishi Takahiro 
Published: December 2004

AbstractK2[Fe(CO)4] (1) with a crown ether was found to be an efficient catalyst for the dimerization of aldehydes to carboxylic esters. Several aromatic aldehydes including furfural gave the corresponding esters in good yields. This reaction also proceeded intramolecularly to give phthalide from phthalaldehyde. However, aliphatic aldehydes gave aldol‐condensation products instead of the corresponding esters. In the reactions of p‐substituted benzaldehydes with 1, the reactivity decreased with increase of the electron‐releasing ability of the substituents. On the basis of these results, the reaction mechanism including the nucleophilic attack of tetracarbonylferrate dianion to the carbonyl carbon is discussed.
The neuroglia in the spinal cord of the newt, Triturus viridescens
Authors: Schonbach Christiane 
Published: December 2004

AbstractThis study of the fine structure of the neuroglia in the spinal cord of the newt, Triturus viridescens, has permitted the identification of three types of glial elements. One type is the ependymal cell whose processes are rich in filaments and glycogen and end on the pia in the deeper portion of the fissures of the cord. The two other types of glial cells display some morphological similarities to typical mammalian neuroglia although they appear to be more primitive. These are the astrocytes and oligodendrocytes. The astrocytes contain glial filaments, glycogen, specialized mitochondria, few ribosomes, and probably send end feet to the surface of the cord and to the intramedullary vessels. The oligodendrocytes present some variation in morphology but always exhibit an abundance of ribosomes. They are located either near the neurons, the intramedullary vessels, the pia, or the myelin sheath.
Projections of the inferior colliculus in cat
Authors: Powell Ervin W. , Hatton James B. 
Published: December 2004

AbstractProjections of the feline inferior colliculus were studied using the Nauta‐Laidlaw method to demonstrate degenerating axons. A subtentorial stereotaxic approach was used to avoid corticofugal degeneration. Direct connections from the inferior colliculus to the anterior midline cerebellar cortex were observed. There is a topographical relationship of fibers of the brachium of the inferior colliculus and parabrachial region to the superior colliculus. A definite projection to the superior colliculi including a pathway through its commissure was found from the parabrachial region. A projection exists from the inferior colliculus to the dorsolateral portion of the central gray as far as the pretectum. There is a projection along the medial portion of the superior colliculus to the pretectum. Projections to the midbrain reticular formation, central gray and superior colliculi were substantial. Thalamic projections include a distribution of fibers to the magnocellular and rostral portion of the principal divisions of the medial geniculate body and to the lateral posterior thalamic nucleus. The rostral connections of the inferior colliculus with areas other than the medial geniculate body indicate that it may function in roles in addition to that of a mass somatomotor reflex center. Possible roles of the inferior colliculus in attention, habituation, and integration of corticovisual and auditory impulses are suggested.
A study of neuronal types in clarke's column in the adult cat
Authors: Loewy Arthur D. 
Published: December 2004

AbstractThree neuronal classes have been identified in Clarke's column in the adult cat. The smallest cells (class A) exhibit variable dendritic branching patterns. Medium‐sized neurons (class B) can be subdivided into multipolar and fusiform cells. The majority of the multipolar cells have elongated perikarya and their dendrites project in a radial fashion, while the fusiform neurons often have their long axis perpendicularly oriented. The large Clarke cells (class C) and their dendrites project in the cranio‐caudal direction. Their dendrites are generally smooth and often extend for over 1000 μ from the perikaryon, but three types of dendritic specializations have been noted: spines, branchlets and varicosities. These specializations are not strictly restricted to Clarke cells. Dendrites of all three cell types cross the nuclear boundaries. Some enter the dorsal columns via Rexed's lamina V and others enter laminae VI, VII and X.Neurons whose cell bodies lie within laminae V, VI, VII and X occasionally send dendrites into Clarke's column.Class A cells account for at least 60% of the total neuronal population of Clarke's column and outnumber the Clarke cells (class C) by approximately three to one. Class B neurons are the least common and form between 6 and 16% of the population.
Electron microscopic studies of wallerian degeneration in rat optic nerves. I. The multipotential glia
Authors: Vaughn James E. , Hinds Patricia Lowary , Skoff Robert P. 
Published: December 2004

AbstractThe development of phagocytes has been studied with the electron and light microscopes in rat optic nerves undergoing Wallerian degeneration. The postoperative survival times ranged from five hours to 250 days. This paper focuses on cells that have been designated either as multipotential glia or as a third neuroglial cell type. Such cells increase markedly in number during the first several weeks of nerve fiber degeneration while the populations of astrocytes and oligodendrocytes remain relatively stable. During this early stage of degeneration, multipotential glial cells develop very irregular shapes and have many processes and complex folds that intermingle with the degenerating nerve fibers. These cells engulf myelin fragments and nerve fibers which become enclosed within vacuoles that show acid phosphatase reaction product in specimens prepared for cytochemistry. The debris containing vacuoles can therefore be considered as phagolysosomes. In addition, the multipotential glial cells show an increase in the number of lipid inclusions over that of cells in normal material. Eventually some multipotential glial cells accumulate large quantities of lipid inclusion and come to resemble the “Gitter” cells described in classical neuropathological studies.The numerical and cytological changes occurring within the multipotential glial population indicate that these cells are an important source of phagocytes in the type of lesion which we have studied. The breakdown of degenerating myelin by multipotential glial cells, the origin of these cells and their relationship to the microglial cells stained in light microscopic preparations are discussed in detail.
Timm's sulfide silver reaction for zinc during experimental anterograde degeneration of hippocampal mossy fibers
Authors: Haug F.‐M. Š. , Blackstad T. W. , Simonsen A. H. , Zimmer J. 
Published: December 2004

AbstractThe boutons of the hippocampal mossy fibers stain particularly well with Timm's sulfide silver reaction for zinc and other metals. In the present study anterograde degeneration was produced in the mossy fibers in the rat by placing lesions in the fascia dentata, after which the Timm reaction was checked at different postoperative intervals. No unequivocal changes were seen as early as five hours after operation. Barely discernible blanching of the affected parts of the mossy fiber layer was observed after seven hours, a significant reduction of stainability was present after ten hours, and a nearly complete loss after 24 hours. The latter situation persisted for the rest of the period studied, viz., up to eight days after operation.Topographical coincidence of reduced Timm staining with areas of anterograde degeneration was verified by impregnating alternating sections of the sulfide treated tissue according to the reduced silver method of Fink and Heimer. These sections moreover confirmed that the affected boutons retain their structural identity for at least several days after the disappearance of the stainability with Timm's method.These findings are compatible with the concept that the zinc may be associated with some rapidly metabolized substance directly or indirectly involved in synaptic transmission.
Enlargement of synaptic vesicles as an early sign of terminal degeneration in the rat caudate nucleus
Authors: Kawana Etsuro , Akert Konrad , Bruppacher Helene 
Published: December 2004

AbstractThe enlargement of synaptic vesicles in degenerating terminals which has recently been demonstrated in the pigeon retino‐tectal fibers as an early sign of secondary degeneration, is confirmed in the rat cortico‐caudate system. Enlarged synaptic vesicles appear already five hours postoperatively in endings which subsequently undergo the classical changes of Wallerian degeneration. Three categories of terminals, SS−, SL− and F‐terminals, are defined on the basis of shape and size of synaptic vesicles in the normal rat caudate nucleus. Only the first category is involved after cortical ablation, while the others remain unchanged.
Organization of subcortical projections of visual areas I and II in the rabbit. An experimental degeneration study
Authors: Giolli Roland A. , Guthrie Mary D. 
Published: December 2004

AbstractSections prepared by the Nauta and Nissl methods have been used to study the subcortical distribution of axon and cell degeneration in rabbits after lesions in visual areas I and II (V I and V II) of the cerebral cortex. Degeneration was limited to the side of the lesions. Following lesions of either V I or V II, two distinct groups of degenerating axons were traced caudally. (i) One of these groups projected through the optic tract and its subjacent nuclei. The terminal portions of its axons were found to form zones of pericellular fiber (or boutonal) degeneration in the thalamic reticular nucleus (TRN), the ventral and dorsal lateral geniculate nuclei (LGv, LGd), the pulvinar (Pul), the nuclei praetectalis anterior and posterior (dorsal and lateral parts respectively), the nucleus tractus opticus, and the superior colliculus (SC). In the TRN, LGd, Pul, and nuclei praetectalis anterior and posterior the zones of degeneration were disposed into distinct columns. After lesions involving V II the terminal portions of these axons were also seen to form zones of pericellular fiber degeneration in the nuclei praetectalis and posterior (ventral and medial parts respectively), the ventrolateral thalamic nucleus, and the zona incerta. (ii) The second group of degenerating axons traversed the cerebral peduncle and the terminal portions of its axons were shown to form zones of pericellular fiber degeneration in the basal pons.Retinotopically organized projections from V I were recognized in the LGv, LGd, Pul, nuclei praetectalis anterior and posterior (dorsal and lateral parts respectively), and SC; and the evidence reveals the presence of similarly organized projections from V II. Other retinotopically organized projections from the visual areas could not be demonstrated.The data support the view that the collateral branches of visual cortical axons serve as a principal source of input to some of the cellular components receiving innervation from the visual areas.Cellular degeneration was confined to the LGd and then present only with lesions involving V I. With each such lesion, the cellular degeneration formed a distinct column within the LGd, and this column and the one consisting of pericellular fiber (or boutonal) degeneration were consistently found to overlap.
Ascending brain stem projections of the anteroventral cochlear nucleus in the rhesus monkey
Authors: Strominger Norman L. , Strominger Adele I. 
Published: December 2004

AbstractIn a series of seventeen rhesus monkeys attempts were made to produce discrete stereotaxic lesions in the anteroventral cochlear nucleus (Av). Anterograde degeneration was described in detail in four cases with lesions confined within the cochlear complex to Av. Fibers decussating at pontine levels coursed exclusively in the trapezoid body. Degenerated fibers projected: ipsi‐laterally to the lateral superior olivary nucleus; bilaterally to the preolivary nuclei; to the lateral side of the ipsilateral medial superior olive and the medial side of the contralateral medial superior olive; and to the contralateral medial trapezoid nucleus. A topographic projection upon the medial superior olive was demonstrated. Projections were bilateral but mainly crossed to the nuclei of the lateral lemniscus and central nucleus of the inferior colliculus; the posterior end of the ipsilateral ventral nucleus of the lateral lemniscus contained an island of profuse degeneration. A few fibers crossed in the commissure of the inferior colliculus. Few if any fibers from Av projected to the contralateral magnocellular medial geniculate.
An autoradiographic study of the time of final division of neurons in rat hypothalamic nuclei
Authors: Ifft Jchn D. 
Published: December 2004

AbstractAn autoradiographic study of the development of 26 nuclei in the rat hypothalamus was made by injecting pregnant rats on different days of pregnancy with tritiated thymidine. The offspring were killed postnatally and the day of gestation on which peak percentages of heavily labeled neurons occurred was considered to be the birthdate of that nucleus. Postnatal animals for the first nine days were injected and were also included in the study. Laterally placed nuclei were found to arise on the fourteenth day of gestation while medial nuclei, in general, arose on day 16. Final cell divisions occurred over a period of time but the majority took place on the days indicated. Apparently a lateromedial gradient exists in the hypothalamus, and possibly a dorsoventral gradient.
Histogenesis of the retina in the killifish, Fundulus heteroclitus
Authors: Hollyfield Joe G. 
Published: December 2004

AbstractThe order of production of retinal cells was studied in embryos of the teleost, Fundulus heteroclitus, using 3H‐thymidine radioautography. Cell division stops first in the fundus of the neuroepithelium and continues longest at the margin. In the fundus, the cells whose nuclei will reside in the inner region of the retina, near the vitreous, stop dividing before the cells whose nuclei will reside near the outer region of the retina. Thus the ganglion cells are produced first and the receptors and horizontal cells last.
Architectonics of the cerebellar nuclei in the rabbit
Authors: O′Leary James L. , Smith Jeanne Marie , Inukai Joseph , Mejia Hugo H. 
Published: December 2004

AbstractA correlative study utilizing Golgi and Golgi Cox sections from 6–12 day rabbits cut serially, and EM material from rabbits two to three months old.Notwithstanding differences in myelinated axon content of neuropil which affect shape and dendrite disposition of individual neurones, there were no major disparities in cellular make‐up of the cerebellar nuclei. Large and medium‐sized cells have dendrites which interdigitate in several patterns depending upon the rosette arrangements to which they belong. At the nuclear‐white matter margin dense overlapping between dendritic terminals and edge‐ramified Purkinje axons occurs. Most medium and all large cells possess centrifugal axons showing recurrent collaterals. Small cells overlapping the medium‐sized ones at 20 μ, belong largely to the short axon class, confirming early studies by Saccozzi (1887) and Lugaro (1895). Their fine axons arborize diffusely within a 250 μ perimeter.Intranuclear arbors of Purkinje axons have funnel or poplar shapes and also contribute to the edge plexus. Besides forming nids about the somata these arbors issue significant extensions along dendrites.Our EM studies bear similarities to those of Eager (′68) for cerebellar nuclei of cat, and lateral vestibular nucleus of that animal by Mugnaini, Walberg, Hauglie‐Hanssen and Brodal (′67). Terminal and passage boutons arise from myelinated axons, reaching dendrites and somata either directly or through nonmyelinated intermediaries. Terminals reminiscent of mossy and climbing fibers can be identified.Axon hillocks of large and small cells show a few synapses each.
Ultrastructural alterations in vestibular and cerebellar nuclei of the ataxic rabbit
Authors: O'Leary J. L. , Fox R. R. , Smith J. M. , Inukai J. 
Published: December 2004

AbstractUsing ultrastructural methods degenrative changes were examined in 16 ataxic (ax/ax) rabbits of The Jackson Laboratory strain. These animals were killed between 4 and 53 days after the onset of symptoms using arterial perfusion of a paraformaldehyde‐glutaraldehyde fixative made up in cacodylate buffer. Ten age matched controls were also studied.Alterations were observed in both neuropil and neurones of the involved nuclei, those in neuropil ordinarily remaining more significant throughout. The neuropil involvement focused upon astrocytes and axon terminals, the astrocytes showing both oedematous swelling and glycogen accumulation, the terminals secondary degeneration of acute and chronic types. Over time the coalescence of swollen glial processes leads to the formation of fluid filled extracellular spaces which appear to result from rupture of astrocytic membranes. That, together with the splitting of the lamellae of myelinated axons to form other lacunae, gives to the neuropil a progressively more spongioform appearance. With the disappearance of degenerating boutons, that vacuolation leads ultimately to loss of the glial investitures of the contained neurones.Large and medium‐sized nerve cells can become involved in either acute or chronic cell change. Nissl substance may undergo compaction around the nucleus, the cytoplasm becoming quite fibrillar with reduction or loss of organelles. Mitochondrial alteration may be the only marker of an involved element. Cell parts in advanced degeneration are wrapped by processes of scavenger cells and removed.Lysosomes are found in excess in degenerating nerve cells, in astrocytes and in macrophages.
Postnatal development of the cerebellar cortex in the rat. II. Phases in the maturation of Purkinje cells and of the molecular layer
Authors: Altman Joseph 
Published: December 2004

AbstractThe growth and synaptic maturation of Purkinje cells and of the molecular layer were studied in the cerebellar cortex of rats aged 0, 3, 5, 7, 10, 12, 15, 21 and 30 days with histological (including Golgi), histochemical, autoradiographic and electron microscopic techniques. Five phases were distinguished in the maturation of Purkinje cells. During the first phase, Purkinje cells become dispersed and aligned in a monolayer but as yet few or no synapses are formed. Next, two transient structures appear: a hypertrophied apical cone composed of „reticular”︁ cytoplasm, and lateral perisomatic processes which establish conspicuous asymmetrical synapses with climbing fibers. During the third phase the perisomatic processes disappear; the „reticular”︁ cytoplasm streams upward into the growing dendrites; the soma is invaded by permanent inconspicuous, symmetrical synapses of basket cells; and, finally, it is surrounded by glial processes, which marks the end of the synaptic maturation of the soma. During the fourth phase parallel fibers form synapses with dendritritic spines in the lower half of the molecular layer. During the fifth phase, which occurs after the disappearance of the external germinal layer, parallel fibers establish synapses with dendritic spines in the upper molecular layer. The „march”︁ of synaptogenesis in the molecular layer from the bottom upward is characterized by three successive events: an initial gradient in the appearance and disappearance of coated vesicles, heralding synaptogenesis; a similar subsequent trend in the formation of synapses; and finally, the interposition in the same sequence of glial processes between Purkinje cell dendrities and parallel fibers, marking the cessation of synaptogenesis.