Effect of auditory deafferentation on the synaptic connectivity of a pair of identified interneurons in adult field crickets

In adult crickets, Teleogryllus oceanicus, unilateral auditory deafferentation causes the medial dendrites of an afferent-deprived, identified auditory interneuron (Int-1) in the prothoracic ganglion to sprout and form new functional connections in the contralateral auditory neuropil. The establishment of these new functional connections by the deafferented Int-1, however, does not appear to affect the physiological responses of Int-1's homolog on the intact side of the prothoracic ganglion which also innervates this auditory neuropil. Thus it appears that the sprouting dendrites of the deafferented Int-1 are not functionally competing with those of the intact Int-1 for synaptic connections in the remaining auditory neuropil following unilateral deafferentation in adult crickets. Moreover, we demonstrate that auditory function is restored to the afferent-deprived Int-1 within 4-6 days following deafferentation, when few branches of Int-1's medial dendrites can be seen to have sprouted. The strength of the physiological responses and extent of dendritic sprouting in the deafferented Int-1 progressively increase with time following deafferentation. By 28 days following deafferentation, most of the normal physiological responses of Int-1 to auditory stimuli have been restored in the deafferented Int-1, and the medial dendrites of the deafferented Int-1 have clearly sprouted and grown across into the contralateral auditory afferent field. The strength of the physiological responses of the deafferented Int-1 to auditory stimuli and extent of dendritic sprouting in the deafferented Int-1 are greater in crickets deafferented as juveniles than as adults. Thus, neuronal plasticity persists in Int-1 following sensory deprivation from the earliest juvenile stages through adulthood.     

Effects of lingual nerve section on morphometric characteristics of reticular nucleus neurons in the kitten brain stem

Computerized morphometric techniques were used to investigate each of 23 parameters in three types of brain stem reticular nucleus neurons in Golgi-stained frontal slices from the brain of 30-day-old kittens after uni- and bilateral lingual nerve section 5–7 days after birth. Particular statistically significant differences in some parameters were discovered in all types of cell. Certain group-specific differences in parameters could be most frequently distinguished in each category: distribution of loose dendritic endings through the dendritic area in reticular neurons, length of dendritic segments in branching cells, and distribution of foci of dendritic arborization in giant multipolar neurons. Unilateral lingual nerve section results in quantitatively more marked deviation from the normal state. It was only under these circumstances, moreover, that differences in overall length of dendrites could be seen, which could indicate a difference in the surface area of the cell.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 23, No. 4, pp. 409–418, July–August, 1991.     

Kinematics of different types of locomotor movements in the deafferented rat

The kinematics of rat hindlimb movements were assessed and compared pre- and post-deafferentation during swimming, forelimb treadmill locomotion plus hindlimb swimming motion, and walking using all four limbs. All types of locomotion were characterized by an increase in the frequency of locomotor rhythm and reduced amplitude of motion at the hindlimb joints following deafferentation. The reduced change observed in the angle of the coxofemoral joint, indicative of a horizontal component in locomotor motion, was mainly brought about by less marked extension. This would confirm evidence indicating that increased load on the extremities, with its ensuing naturally-occurring afferent outflow, is accompanied by a reduced locomotor motion rate and a rise in the amplitude of the latter due to intensified extension of the limb. The increased forward carriage of the hind limb seen during the transition to four-legged locomotion persisted after deafferentation; this may be considered a sign of coordination amongst the limbs. Deafferentation led to a reduction in the MEG of muscle activity, which was found to be lowest in swimming and highest during walking. The role of the afferent inflow in shaping different types of locomotor motion is evaluated.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 4, pp. 520–525, July–August, 1987.     

Characteristics of electrotonic spread along the dendritic tree of retinal ganglion cells

Morphometric investigations of four types of dendritic trees of frog retinal ganglion cells show that these trees cannot be satisfactorily represented by an equivalent cable cylinder. In calculations of the electrotonic characteristics the geometric properties of the dendritic trees were accordingly considered. The following electrotonic characteristics were calculated for steady-state excitation: input resistances, coefficients of electrotonic transmission, and electrotonic efficiency of the bifurcations and the middle and end of the dendritic segments, as well as the electrotonic length of the dendritic tree and input resistances of the cell body. Model investigations showed that the electrotonic characteristics are determined mainly by extensiveness. The calculated values of electrotonic efficiency point to the physiological importance of the electrotonic spread of excitation in the dendrites of the retinal ganglion cells.Kaunas Medical Institute. Translated from Neirofiziologiya, Vol. 6, No. 3, pp. 304–311, May–June, 1974.     

Investigation of the geometry of the dendritic tree of retinal ganglion cells

Two parameters are proposed for classifying the structure of the dendritic trees of retinal ganglion cells: the mean distance between the ends of the terminal segments of the dendrites from the soma ( ) and the ratio between the number of horizontal and vertical dendritic segments (a). By using these parameters the dendritic trees of ganglion cells were divided into four types. To describe the two-dimensional structure of dendritic trees the following parameters are used: the distribution of intermediate and terminal dendritic segments in each series of branches depending on the angle of their orientation relative to the boundaries of the inner plexiform layer — p_Z (), q_Z (), and depending on their length — P_Z (1), q_Z (1). Histograms of these functions are given. By means of these histograms the two-dimensional structure of the dendritic tree can be drawn in such a way as to reproduce the structural features of actual dendritic trees with the accuracy of the parameters defining their appearance. The structural and functional significance of the parameters used is discussed.Kaunas Medical Institute. Translated from Neirofiziologiya, Vol. 5, No. 3, pp. 307–314, May–June, 1973.     

Dependence of efferent activity parameters on limb position during fictitious scratching in decerebrate cats

The influence of tonic afferent inflow as conditioned by ipsilateral hindlimb position on the efferent activity parameters of the spinal generator governing scratching motion was investigated in immobilized decerebrate cats. A significant correlation was observed between motor activity parameters and ensuing bouts of scratching in the absence of afferent flow (after deafferentation of the limbs). This correlation was less pronounced when afferentation remained intact and declined when the limb was shifted from the "aimed" to either the "overaimed" or "deflecting backwards" placing of the limb. The statistically significant correlations found between the parameters of different stages of motor activity and their dependence on hindlimb positions during actual scratching could be responsible for the stability of intended placing of the limbs during the performance of oscillatory movements. Hindlimb deafferentation would appear closest to "aimed" position judging by the parameters of efferent activity and the nature of correlations between them.A. A. Bogomolets Institute of Physiology. Academy of Sciences of the Ukrainian SSR. Kiev. Translated from Neirofiziologiya, Vol. 15, No. 5, pp. 636–645, September–October, 1986.     

Reflex component of the swing phase: A comparative analysis of rat locomotion before and after deafferentation

A comparative analysis was made of the kinematics of movement and EMG activity during different types of locomotion before and after bilateral deafferentation of segments L₁-S₂ of the rat spinal cord. It was found that deafferentation is accompanied by a reduction in the amplitude of locomotor movements and by a delay in both the initiation and increase in duration of flexion in the knee and ankle joints during the swing phase, without producing much effect on the time course of hip joint flexion. An increase in the F period of the swing phase, at its lowest during swimming and highest during stepping, was also discovered, which accordingly rose in step with increasingly deficient afferent inflow. Flexor activity rose especially noticeably during dragging on the limb in the swing phase post-deafferentation. The role of peripheral afferent influence in shaping the F (swing) phase is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 5, pp. 654–659, September–October, 1987.     

Dendritic action potentials of pyramidal tract neurons in the cat sensorimotor cortex

The intracellular activity of pyramidal tract neurons was studied during electrical stimulation of ventrolateral and ventroposterolateral thalamic nuclei in acute experiments on cats immobilized by myorelaxants. Somatic action potentials were observed and spontaneous spikes were also produced by single and rhythmic stimulation of the thalamic nuclei at the rate of 8–14 Hz, by iontophoretic application of strychnine, and by intracellular depolarizing current pulses. These potentials had a relatively low and variable amplitude of 5–60 mV and are presumed to be dendritic action potentials. It is postulated that these variable potentials arise in the dendrites of pyramidal neurons with multiple zones generating such activity. No interaction was observed where somatic and dendritic action potentials occur simultaneously. The possible functional role of dendritic action potentials is discussed.I. S. Beritashvili Institute of Physiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 18, No. 4, pp. 435–443, July–August, 1986.     

Responses of cortical neurons to local application of excitatory amino acids to their dendrites and soma

The efficacy of excitation induced by iontophoretic application of excitatory amino acids to the soma or different parts of the dendritic tree has been compared in experiments performed on parietal cortex slices. Spike activity was recorded extracellularly from single nerve cells of layer V. In total, the responses of 125 neurons were analyzed. Upon application of glutamate and aspartate to the neuronal soma and the majority of dendrites, latencies of excitatory responses did not exceed 500 msec. In 18% of cases, neuronal responses to transmitter application to basal and apical dendrites had longer (2–3 sec) latencies. The maximum intensity of responses was observed when excitatory amino acids had been applied to the soma or proximal parts of dendrites. If applied at a distance of over 100 µm to basal and 300 µm to apical dendrites, glutamate and aspartate elicited cellular responses whose intensity was 2–3 times lower than that of the responses induced by application to the soma. The maximum distances at which somatic spike responses could be recorded were 350 µm and 800 µm for basal and apical dendrites, respectively. Different latencies of the responses to somatic and dendritic applications of excitatory amino acids in some neurons, as well as high efficacy of responses to stimulation of remote parts of dendritic tree, may indicate nonidentity of electrical properties of dendritic and somatic membranes.Neirofiziologiya/Neurophysiology, Vol. 25, No. 6, pp. 437–446, November–December, 1993.     

Aspects of synaptic reorganization in the cat sensorimotor cortex after lesion of the symmetrically contralateral hemisphere

During the course of acute experiments, response in cortico-spinal neurons (CSN) to stimulating the ipsilateral ventral thalamic nucleus was investigated by extracellular recording techniques in intact adult cats and others with lesioning inflicted on the contralateral sensorimotor cortex 6–18 months previously. An accelerated stage of growth was noted in monosynaptic IPSP and CSN with slow-conducting axons in animals with surgically-induced lesion, suggesting reorganization of synaptic contacts within the CSN somatodendritic membrane. The collision test was applied to make a complete examination of arborization and of other aspects of CSN axons, as well as the presence of collaterals running to the ventrolateral thalamic nucleus and helping to form the ipsilateral pyramidal tract. The significance is discussed of plastic synaptic rearrangement in the ipsilateral thalamo-cortical reverberating system for formation of the efferent spike train during partial interhemisphere cortical deafferentation.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 22, No. 5, pp. 612–621, September–October, 1990.     

Possible mechanisms of dendritic potential habituation in the cat association cortex

The effect of application of strychnine and calcium and of post-tetanic potentiation on the dynamics of gradual decay of dendritic potentials in the association cortex, which is regarded as monosynaptic habituation, was studied in acute experiments on cats anesthetized with pentobarbital. Despire a significant increase in amplitude of dendritic potentials after strychnine application or calcium enrichment of the physiological saline, the time course of habituation was unchanged. The course of habituation also remained unchanged during post-tetanic potentiation. It is concluded that habituation of dendritic potentials is due to processes taking place in the postsynaptic dendrite membrane itself and is independent of postsynaptic inhibition or transmitter exhaustion in presynaptic endings.I. S. Beritashvili Institute of Physiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 16, No. 2, pp. 208–213, March–April, 1984.     

Exosome-based immunotherapy

Exosomes are small membrane vesicles originating from late endosomes and secreted by hematopoietic and epithelial cells in culture. Exosome proteic and lipid composition is unique and might shed some light into exosome biogenesis and function. Exosomes secreted from professional antigen-presenting cells (i.e., B lymphocytes and dendritic cells) are enriched in MHC class I and II complexes, costimulatory molecules, and hsp70–90 chaperones, and have therefore been more extensively studied for their immunomodulatory capacities in vitro and in vivo. This review will present the main biological features pertaining to tumor or DC-derived exosomes, will emphasize their immunostimulatory function, and will discuss their implementation in cancer immunotherapy.Abbreviations APC antigen-presenting cell - ASI active specific immunotherapy - CTL cytotoxic T lymphocyte - DC dendritic cell - FDC follicular dendritic cell - MD-DC monocyte-derived dendritic cell - GMP good manufacturing procedure - HLA human leukocyte antigen - HSP heat shock protein - MHC major histocompatibility complex - MVB multivesicular body - ExAs ascitis-derived exosomes - DEX DC-derived exosome - TEX tumor cell–derived exosome This work was presented at the first Cancer Immunology and Immunotherapy Summer School, 8–13 September 2003, Ionian Village, Bartholomeio, Peloponnese, Greece.     

Development of activity in intercostal-muscle motor nuclei in the thoracic section (intact and deafferentated) of the spinal cord

During a respiratory period there is regular recruitment of units with different characteristics of impulse discharge in the motor nuclei of the intercostal muscles. The unit discharges terminate randomly. After bilateral deafferentation of the thoracic section the frequency of impulses of intercostal motor units (MU), the regularity of their recruitment, and the sequence of activity of expiratory and inspiratory motor nuclei were nearly normal. Hence it is concluded that segmental afferentation is not necessary for coordinated activity of the two nuclei in normal respiration.Institute of Problems of Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 3, No. 2, pp. 194–199, March–April, 1971.     

Limb movement,intensity of integral afferent impulses from limb receptors,and level of primary afferent terminal polarization during locomotion in cats decerebrated at high level

The relationship between parameters of electrical muscle activity, changes at hindlimb joint angles, intensity of integral afferent flow, and dorsal root potential during real-life locomotion was investigated in cats decerebrated at high level. Characteristics of rear limb movements before and after deafferentation were described. It was found that afferent activity during locomotion motion consists, of two components — a tonic and a periodic phasic stage. Three main waves may be distinguished in the latter, each of which gives rise to associated changes in the level of primary afferent terminal polarization. These changes in turn are summated with the effects produced by the central generator. Correlations, between the parameters of these processes were investigated and the mechanisms underlying afferent control of locomotion generator function discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 1, pp. 119–127, January–February, 1988.     

Correlation between the kinematics of hindlimb movement and efferent activity in the decerebrate cat during scratching

The statistical relationship was investigated between temporal and amplitude parameters of scratching motion performed by the hindlimb and those of muscular activity during naturally-occurring scratching in the course of experiments on decerebrate cats. The factors mainly determining movement parameters, such as amplitude or the speed and duration of a specific phase were found to be the intensity of EMG activity displayed by scratching and aiming muscles and the duration of aiming muscle activity. Findings from experiments involving limb deafferentation showed that the statistical relationship between the parameters of motion and muscular electrical activity reflect certain patterns of scratch generator operation. Certain relationships linking parameters of electrical activity changed due to the effects of afferent signals.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 4, pp. 525–533, July–August.     

Ganglioside sialidase activity in bovine neuronal perikarya

Neuronal perikarya were isolated, using bulk preparative procedures, from bovine brains. Synaptosomes, neuronal perikarya, and brain homogenates had similar ganglioside patterns, with the synaptosomes containing at least four times more total ganglioside per mg protein than the neuronal perikarya and twice that of the homogenate. Synaptosomes had 26–33 nmol total sialic acid/mg protein, while the neurons had only 15–17 nmol. Determination of ganglioside sialidase activity showed that neuronal perikarya had very low levels (negligible), in comparison with synaptosomes or whole-brain homogenates. Trypsin treatment during the isolation procedure enhanced sialidase activity two-to threefold in the particulate fraction of the whole-brain homogenate. Determination of the distribution of sialidase activity in the fractions obtained during the isolation of the neuronal perikarya showed that the sialidase activity was associated with the myelin, broken-off dendritic processes, and glial-cell fractions that banded in the less dense sucrose.     

Dendritic structure in neurons of embryo amygdala grafts

Brain preparations stained by Golgi's technique in grafts of rat embryo basolateral amygdaloid nucleus were transplanted into the intact brain and the cavity produced by electrolytic destruction of the adult rat amygdala, revealing two types of neurons — sparsely and densely arborizing cells. It was found from comparing grafted with intact units that length and arborization of the cell had increased in sparsely arborizing cells after grafting, whereas the cell body had decreased in size and dendrites lengthened in densely arborizing units; neuronal arborization had also increased considerably. It was found from analyzing polar histograms of dendritic density distribution that neurites of transplanted neurons are selectively orientated depending on the area where the graft has united with the host brain. Altered neuronal geometry is assumed to be a factor determining the graft's ability to contribute to compensatory functions of the lesioned brain.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 22, No. 5, pp. 579–586, September–October, 1990.     

Zooplankton in a quasi-stable phase in an endorheic lake (Lake Chilwa,Malawi)

Lake Chilwa, a fairly large, turbid, brackish and very shallow endorheic lake in Malawi, Central Africa, dried up completely in 1968 and filled up again in the following wet season. Compared with the zooplankton in the drying, filling and post-filling phases (1966–1971), differences in their composition, density, distribution and reproduction were found in 1975–1976, a year when the lake was 1–2 metres deeper. This situation is discussed in relation to environmental factors, fish predation and the supply of detritus from the surrounding Typha swamp, to illustrate the relative stability of the zooplankton populations in periods between lake recessions.University of Malawi