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  • 1
    Electronic Resource
    Electronic Resource
    Destruction of external granular layer and subsequent cerebellar abnormalities (1983)
    Springer
    Acta neuropathologica 59 (1983), S. 41-47 
    Details
    ISSN: 1432-0533
    Keywords: Cytosine arabinoside ; Cerebellum ; External granular layer ; Purkinje cell ; Heterotopic granule cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study was undertaken to elucidate the relationship between the time of destruction of the external granular layer and subsequent cerebellar abnormalities. Mice were injected s. c. with 30 mg/kg body weight (b. wt.) of cytosine arabinoside on days 2, 3, and 4, on days, 4, 5, and 6, on days 7, 8, and 9, and on days 10, 11, and 12, and designated as group I, II, III, and IV, respectively. In group I, disarrangement of Purkinje cells and heterotopic granule cells in the molecular layer were observed on all lobes of cerebellum. Heterotopic granule cells were seen on all lobes in group II, whereas disarrangement of Purkinje cells was observed only in the region from the anterior to middle lobes. In group III, heterotopic granule cells were limited to the area from anterior to middle lobes, but there was no disarrangement of Purkinje cells. Group IV cerebellum did not show abnormal cytoarchitecture. Golgi-Cox studies showed abnormal arborization of Purkinje cells in each experimental group. They were arbitrarily classified into inverted Purkinje cells, lying Purkinje cells, T-shaped Purkinje cells, and poorly arborized Purkinje cells. The earlier the postnatal treatment the more severe were the abnormalities of Purkinje cell dendrite. According to the electron-microscopic study, some glomerular synaptic complexes, which are normally confined to the internal granular layer, were observed even in the molecular layer in groups I, II, and III. Some of the Purkinje cell dentritic spines did not make synapses with parallel fibers in any of the experimental groups. The results indicate that severity of abnormal arborization of Purkinje cells is dependent on the period of destruction of the external granular layer. Formation of heterotopic granule cells was dependent on the destruction of the external granular layer up to day 10 after birth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690315
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  • 2
    Electronic Resource
    Electronic Resource
    Synaptic changes in Purkinje cell dentritic spine of mouse cerebellum after neonatal administration of cytosine arabinoside (1983)
    Springer
    Acta neuropathologica 60 (1983), S. 19-23 
    Details
    ISSN: 1432-0533
    Keywords: Synapse ; Dentritic spine ; Purkinje cell ; Neuronal compensation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study was undertaken to elucidate morphological changes in the synaptic area of the Purkinje cell dendritic spines when granule cells were decreased in number. The mice were injected s. c. with 30 mg/kg b. w. of cytosine arabinoside on days 2, 3, and 4, and on days 7, 8 and 9, and were designated as group I and group II, respectively. The mice injected with saline on days 2, 3, and 4 served as control. The cerebella of the mice in each group were examined by electron microscopy on days 30, 60, and 90. Using photographs thus obtained, the synaptic length and area of Purkinje cell dendritic spines which participated in synapses with axons of granule cells were measured by computer. In the controls, these spines did not increase significantly either in synaptic length or in spine area in the duration from 30 to 90 days after birth. In the 90-day-old mice belonging to group I and group II, however, they increased by about 20% in the synaptic length and by about 35% in the spine area as compared to those in age-matched control. The elongation and enlargement show that the synaptic surface on the spine spreads to compensate for synapses lost by reduction in number of granule cells in experimental groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00685343
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  • 3
    Electronic Resource
    Electronic Resource
    Properties of mesencephalic reticulospinal neurons in the cat (1980)
    Springer
    Experimental brain research 41 (1980), S. 75-78 
    Details
    ISSN: 1432-1106
    Keywords: Mesencephalic reticulospinal neurons ; Conduction velocities ; Vestibular system, semicir cularcanal inputs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neurons that project to the spinal cord were located in the mesencephalic reticular formation outside the interstitial nucleus of Cajal in cerebellectomized cats under chloralose anesthesia. Of these neurons 40% responded only at C1 (reticulospinal N cells) and the remaining 60% responded at C4 also (reticulospinal D cells). Conduction velocities of N cells were significantly slower than those of D cells. N cells and D cells responded similarly to stimulation of the whole vestibular nerves and vestibular nuclei. However, they differ in semicircular canal inputs; N cells were more responsive to canal stimulation. Comparison of properties between mesencephalic reticulospinal and interstitiospinal neurons (Fukushima et al. 1980) showed that many reticulospinal and interstitiospinal neurons have similar properties, suggesting that functionally similar neurons may be found distributed over more than one anatomically defined cell group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236681
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of stimulation of frontal cortex, superior colliculus, and neck muscle afferents on interstitiospinal neurons in the cat (1981)
    Springer
    Experimental brain research 44 (1981), S. 143-153 
    Details
    ISSN: 1432-1106
    Keywords: Interstitiospinal neurons ; Pericruciate cortex ; Frontal eye fields ; Superior colliculus ; Neck muscle afferents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Interstitiospinal neurons were activated by antidromic stimulation of the spinal cord ventromedial funiculus at C1 and C4 in cerebellectomized cats under chlor alose anesthesia. Neurons responding only to C1 were classified as N cells and those responding both to C1 and C4 were classified as D cells, as in previous experiments (Fukushima et al. 1980a). Vestibular branching interstitiospinal and reticulospinal neurons were also identified as in the previous experiments. Stimulation of the ipsilateral pericruciate cortex evoked firing in 31% of N cells, 41% of D cells and 35% of vestibular branching neurons, while stimulation of the contralateral cortex excited 6% of N cells, 29% of D cells and 14% of vestibular branching neurons. Response latencies ranged from 2 to 15 ms after the effective pulse. By measuring the thresholds of activation of these neurons while changing the depth of the stimulating electrodes, and by mapping the cortical areas, it was shown that the lowest threshold areas were in the frontal eye fields and the anterior sigmoid gyrus near the presylvian sulcus (Area 6). Stimulation of the latter area often evoked neck or shoulder muscle contraction. Stimulation in the deep layers of the ipsilateral superior colliculus evoked firing in about 20% of interstitiospinal neurons and about 42% of vestibular branching neurons, with typical latencies 2–3 ms after the effective pulse, while stimulation of the contralateral superior colliculus was rarely effective. N cells and D cells responded similarly. Thresholds for activation were high in the intermediate tectal layers and declined as the electrodes entered the underlying tegmentum. This suggests that the superior colliculus is not the main source of synaptic inputs to these neurons. Low threshold points were found above the deep fiber layer when stimulating electrodes were inserted into the pretectum. Stimulation of the C2 biventer cervicis nerve excited about 8% of N cells, 18% of D cells, and 15% of vestibular branching neurons bilaterally with typical latencies around 10 ms. Similar results were obtained when C2 splenius nerves were stimulated. The fibers responsible for such excitation are probably group II, since stimuli stronger than 1.8 times threshold of the lowest threshold fibers were needed to evoke excitation. Response decrement was often observed when stimuli were repeated at 1/s, while no such decrement was observed at the rate of 1/3 s. When the convergence of cortical and labyrinthine excitatory inputs was studied, 36% of interstitiospinal neurons received single inputs either from the pericruciate cortex or from the labyrinth, 22% of neurons received convergent excitation from both and the remaining 42% did not respond to either stimulus. Although vestibular branching neurons rarely received labyrinthine inputs, they frequently showed convergence of excitation to stimulation of the frontal cortex, superior colliculus and vestibular nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237335
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  • 5
    Electronic Resource
    Electronic Resource
    Responses of cat vestibular neurons to stimulation of the frontal cortex (1984)
    Springer
    Experimental brain research 56 (1984), S. 275-278 
    Details
    ISSN: 1432-1106
    Keywords: Vestibular neurons ; Vestibulocollic reflex ; Precruciate cortex ; Frontal eye fields
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To study the neural basis for the regulation of vestibulocollic reflexes during voluntary head movements, the effects of stimulation of the precruciate cortex near the presylvian sulcus (neck area of the motor cortex) and the frontal eye fields (FEF) on vestibular neurons were studied in cerebellectomized cats anesthetized with α chloralose. Neurons were recorded in the medial and descending vestibular nuclei and antidromically identified from C1. Stimulation of the FEF and precruciate cortex fired 29 and 13% of neurons that did not exhibit spontaneous activity. About 80% of spontaneously discharging neurons were influenced by stimulation of either of the two. Stimulation of the precruciate cortex or FEF suppressed or facilitated labyrinthine evoked monosynaptic activation of vestibulospinal neurons, suggesting that the frontal cortical neurons have the properties to regulate the vestibulocollic reflexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236283
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  • 6
    Electronic Resource
    Electronic Resource
    Responses of cat mesencephalic reticulospinal neurons to stimulation of superior colliculus, pericruciate cortex, and neck muscle afferents (1981)
    Springer
    Experimental brain research 44 (1981), S. 441-444 
    Details
    ISSN: 1432-1106
    Keywords: Mesencephalic reticulospinal neurons ; Superior colliculus ; Pericruciate cortex ; Neck muscle afferents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neurons were recorded extracellularly in the mesencephalic reticular formation outside the interstitial nucleus of Cajal in cerebellectomized cats anesthetized with α chloralose. Reticulospinal neurons were identified by antidromic stimulation of the upper cervical segments. Stimulation in the deep layers of the ipsilateral superior colliculus evoked firing in 36% of reticulospinal neurons. For many neurons thresholds for activation were high in the intermediate tectal layers and declined as the electrodes entered the underlying tegmentum. However, low threshold points were found above the deep fiber layer within the superior colliculus for some cells. Stimulation of the contralateral superior colliculus excited 10% of neurons and thresholds for activation were high above the deep fiber layer for all neurons. Stimulation of the ipsilateral and contralateral pericruciate cortex excited 39 and 21% of neurons, respectively. The lowest threshold area was found in the frontal eye fields. Sixteen percent of neurons received excitation from neck muscle afferents (C2 biventer-cervicis) bilaterally. Comparison of responses between mesencephalic reticulospinal neurons and interstitiospinal neurons (Fukushima et al. 1981) showed that responses of the two groups of neurons were similar when the pericruciate cortex and neck muscle afferents were stimulated. However, a difference was observed in tectal responses, since low threshold points were rarely observed above the deep fiber layer for interstitiospinal neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238838
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  • 7
    Electronic Resource
    Electronic Resource
    Location and vestibular responses of interstitial and midbrain reticular neurons that project to the vestibular nuclei in the cat (1982)
    Springer
    Experimental brain research 45 (1982), S. 303-312 
    Details
    ISSN: 1432-1106
    Keywords: Midbrain reticular formation ; Interstitio-vestibular neurons ; Vestibular system ; Semicircular canal inputs ; Axon branching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experiments were performed on cats anesthetized with a chloralose to locate neurons in and around the interstitial nucleus of Cajal (INC) that project to the vestibular nuclei, and to study labyrinthine inputs to these neurons. Neurons that project to the vestibular nuclei were identified by microstimulation confined to the vestibular nuclei on both sides. All neurons thus identified were activated antidromically from the ipsilateral (but not contralateral) vestibular nuclei. Vestibular projecting neurons were found in the INC and the reticular formation rostral, dorsal and caudal to the INC. About 23% of these neurons were vestibular branching spinal projecting neurons. The median conduction velocity of vestibular projecting neurons was estimated to be in the neighborhood of 12–16 m/s. Stimulation of the contralateral vestibular nerve evoked firing in 29% of neurons projecting to the vestibular nuclei, but not to the spinal cord. Interstitial neurons responded more frequently than reticular neurons (45% vs 11%, χ2 test, p 〈 0.001). By stimulation of individual semicircular canal nerves, it was shown that vestibular projecting neurons receive excitation from the contralateral vertical canals, but do not receive substantial inputs from the horizontal canal. Stimulation of the ipsilateral vestibular nerve excited 10% of neurons; suppression of activity was observed for six cells and four of the six were excited by stimulation of the contralateral vestibular nerve. Stimulation of ipsilateral individual semicircular canal nerves did not excite any cells tested; the activity of a few cells was suppressed by stimulation of the vertical canal nerves. One neuron received excitation from the contralateral anterior canal and suppression from the ipsilateral posterior canal. Vestibular branching spinal projecting neurons rarely received labyrinthine inputs as already reported (Fukushima et al. 1980a). These results suggest that vestibular projecting neurons may be involved in vertical vestibular reflexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235791
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  • 8
    Electronic Resource
    Electronic Resource
    Observation on the floating seaweeds of near-shore waters of southern Japan (1984)
    Springer
    Hydrobiologia 116-117 (1984), S. 408-412 
    Details
    ISSN: 1573-5117
    Keywords: floating seaweeds ; Sargassum ; southern Japan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027711
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  • 9
    Electronic Resource
    Electronic Resource
    Freeze-dried cellulose acetate membrane fine structure observation (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 3229-3243 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A freeze-dried cellulose acetate membrane fine structure was observed with an ultrathin sectioning electron microscope. The fine structure for the top surface in this membrane could be seen by lead citrate staining ultrathin sectioning. This network structure was observed among pores, which existed in porous substrate. The pore diameter in the top surface was about 50 Å, a value that agrees approximately with the value estimated by gas permeation.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.170181109
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  • 10
    Electronic Resource
    Electronic Resource
    Mixed gases separation by fine porous freeze-dried cellulose acetate membrane (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 583-594 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A Freeze-dried cellulose acetate membrane with high permeability and high separation factor was prepared. In the successive membrance process, the heat treatment temperature was 80°C for constant period of 10 min, acetone evaporation time was between 4 and 6 min, and the membrane was fixed during drying to prevent shrinkage. Gas permeabilities for such a membrane were inversely proportional to the square root of molecular weight, suggesting that the mechanism of gas flow through this membrane was Knudsen flow. Separation factors for H2—He, Ar—Kr, N2—Kr, He—Ne, H2—Ne, He—Ar, Ar—H2, He—Kr, Ar—He, and He—H2 were measured. These factors were higher than those of membranes reported already. Separation efficiency largely depended upon the combination of mixed gases. The combination of two atom molecules and one atom molecule lowered the separation efficiency compared with the combination of one atom molecule and one atom molecule.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070290213
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