• Journal of Korean Neurosurgical Society
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• v.46 no.1
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• pp.1-4
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• 2009

Objective: To report an unsuspected adaptive plasticity of single upper motor neurons and of primary motor cortex found after microsurgical connection of the spinal cord with peripheral nerve via grafts in paraplegics and focussed discussion of the reviewed literature. Methods: The research aimed at making paraplegics walk again, after 20 years of experimental surgery in animals. Amongst other things, animal experiments demonstrated the alteration of the motor endplates receptors from cholinergic to glutamatergic induced by connection with upper motor neurons. The same paradigm was successfully performed in paraplegic humans. The nerve grafts were put into the ventral-lateral spinal tract randomly, with out possibility of choosing the axons coming from different areas of the motor cortex. Results: The patient became able to selectively activate the re-innervated muscles she wanted without concurrent activities of other muscles connected with the same cortical areas. Conclusion: Authors believe that unlike in nerve or tendon transfers, where the whole cortical area corresponding to the transfer changes its function a phenomenon that we call "brain plasticity by areas". in our paradigm due to the direct connection of upper motor neurons with different peripheral nerves and muscles via nerve grafts motor learning occurs based on adaptive neuronal plasticity so that simultaneous contractions of other muscles are prevented. We propose to call it adaptive functional "plasticity by single neurons". We speculate that this phenomenon is due to the simultaneous activation of neurons spread in different cortical areas for a given specific movement, whilst the other neurons of the same areas connected with peripheral nerves of different muscles are not activated at the same time. Why different neurons of the same area fire at different times according to different voluntary demands remains to be discovered. We are committed to solve this enigma hereafter.

• Biomedical Science Letters
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• v.29 no.4
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• pp.330-335
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• 2023

The corazonin (Crz) gene showed two subtypes of different length at laval and pupal stage. The long subtype fade out in adult central nerve system (CNS) but the short one survive through all the life cycle from larva to adult. The short subtype has the same base sequences with mature Crz mRNA and detected in both brain and ventral nerve cord (VNC). The long one, on the contrary, was detected only in the brain tissue. As observed in above results, Crz neurons develop in different pattern in the CNS of scuttle fly and the Crz gene expresses two different subtypes. These results suggest that this neurotransmitter may perform differential neurophysiological functions in the scuttle fly. Variation in the amino acid composition of the final active undecapeptide supports in strong those possibilities. We expect further studies on the relationship between neurophysiological functions of Crz and behavioral characteristics of the scuttle fly.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.3
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• pp.284-288
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• 2018

The scuttle fly central nervous system (CNS) is unobservable during egg and larvae instar stage 1. During days 2~3 of larvae instar stage 2, the left and right hemisphere of the brain can be observed. Below the brain, the subesophageal ganglion (SOG) connects to the ventral nerve cord (VNC). During days 3~5 of larvae instar stage 3, the CNS enlarged slightly with no other changes. During days 1~3 of the pupal stage the CNS moved to the head with no distinguishable changes from the previous stage. During days 4~6 of the pupal stage, the left and right hemisphere of the brain had fused into one mass and the optic lobe (OL) located on the side of the brain completed its development. During days 7~9 of the pupal stage, the OL began to show eyeball pigment. The SOG was connected to the brain and the VNC began to separate, which was accompanied by an increase in nerve fibers. During days 10~12 of the pupal stage, the brain of the CNS and VNC was clearly distinguished and the brown pigmentation of OL became darker. During days 13~15 days of the pupal stage, the separated brain and VNC became connected by thin nerve fiber. The VNC began to separate into two with a greater increase in nerve fibers. The adult fly showed similar features to the previous stage, but the brain was located in the head and the VNC in the chest.

• Journal of Korean Neurosurgical Society
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• v.65 no.1
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• pp.138-144
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• 2022

To report two cases of type 1.5 split cord malformation (SCM), a subtype of SCM with combined characteristics of types I and II and to review the relevant literature and propose a new possible pathogenetic theory for type 1.5 SCM. A 52-year-old woman had hemicords within a single dural sac with a dorsal bony septum at the L5 level. A 9-year-old boy had hemicords within a single dural sac with a ventral bony septum and fibrous extension at the L3 level. Both patients underwent microsurgical treatments for removing the bony septum, detethering the spinal cord, and sectioning the filum terminale. The surgical procedure revealed an extradural partial bony septum and hemicords within an intact single dural sac in each patient. Both patients were discharged from the hospital without de novo nerve dysfunction. Published cases have validated that types I and II SCM can overlap. We recommend recent type 1.5 SCM as a normative terminology for this overlapping SCM and report two rare cases of this SCM. We propose an associated pathogenesis consisting of uneven distribution and regression to explain type 1.5 SCM. Furthermore, we postulate that the amount of condensing meninx primitiva might determine whether the left bony septum has fibrous extensions to the opposite dura in type 1.5 SCM.

• Journal of Chest Surgery
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• v.20 no.3
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• pp.439-450
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• 1987

The arterial blood pressure response elicited by stimulating the peripheral afferent fibers of different groups and origins was studied in cats. Experimental animals were anesthetized with a-chloralose [60mg/kg] and artificially ventilated with a respirator. The lumbosacral spinal cord was exposed through a laminectomy and L7 ventral root was isolated. The sural, medial gastrocnemius and common peroneal nerves were also exposed in the hindlimb. The arterial blood pressure was monitored continuously while the exposed peripheral nerves and L7 ventral root were being stimulated. Then, spinal lesions were made on the dorsolateral sulcus area, dorsolateral funiculus and other areas at the thoracolumbar junction. The arterial blood pressure responses were compared before and after making spinal lesions. The following results were obtained. 1. The mean arterial blood pressure was elevated from 103*7.3 to 129*8, 1 [mean*S.E.] mmHg [p<0.001] during stimulation of the sural nerve with C-strength [1000T], 20Hz. Stimulation with Ad-strength, 1Hz resulted in the depression of the arterial pressure by 8 mmHg [p<0.01]. 2. Stimulation of the medial gastrocnemius nerve with Ad-strength did not elicit any significant change in arterial blood pressure. Stimulation with C-strength, 20 Hz induced a pressor response from 102*6.2 to 117*6.4 mmHg [p<0.01] while that with C-strength, 1Hz induced a depressor response from 104*6.1 to 93*4.9 mmHg [p<0.001]. 3. A pressor response by 56 [from 107*7 5 to 163*9.4] mmHg [p<0.001] was induced during stimulation of the common peroneal nerve with C-strength, 20Hz stimuli. Stimulation with A4-strength, 1Hz depressed the arterial blood pressure from 111~9.3 to 94*7.8 mmHg [P<0.005]. The activation of the ventral root afferent fibers with C-strength, 20 Hz stimuli induced a pressor response by 22 mmHg [from 115*9.4 to 137*8.6 mmHg] [p<0.001]. 4. The pressor response elicited during stimulation of the sural nerve was abolished by making lesions on the dorsolateral sulcus area bilaterally. With the medial gastrocnemius nerve, the pressor response had not been abolished completely by the dorsolateral sulcus lesions. The pressor response disappeared completely with addition of the bilateral dorsolateral funiculus lesions. 5. The depressor response induced by stimulation of the sciatic nerve with Ad-strength, 1Hz was decreased by making lesions on the dorsolateral funiculus. 6. From the above results it is concluded that the difference in the blood pressure responses to the activation of the muscular afferent and the cutaneous afferent fibers is responsible for the groups of afferent fibers and the spinal ascending pathways.

• Toxicological Research
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• v.13 no.4
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• pp.317-322
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• 1997

Acute delayed neurotoxicity of KH-502 [O.O-Diethyl O-(1-phenyyl-3-trifluoromethyl-5-pyrazoyl) thiophosphoric acid ester], an insecticide synthesized newly in Korea, was studied in White Leghorn hens. The doses were determined on the basis of preliminary $LD_{50}$ study. High, middle and low doses were determined to be 1123 mg/kg, 762 mg/kg and 518 mg/kg, respectively. The animals were pretreated with atropine (30 mg/kg) prior to administration of KH-502. The chemical was administrated at the first and 21st day of the study. As positive controls, animals were admlnistrated with triorthocresylphosphate (TOCP 1000 mg/kg and 500 mg/kg). Animals administrated with TOCP or KH-502 were sacrificed by perfusion-fixation at 21st and 42nd day of the study, respectively. The central and peripheral nerve tissues were routinely treated for microscopic observation. As results, eight, three, one, and one chickens died within 2 day after adminiatration with signs of cholinergic acute toxicity in high, middle low and TOCP dose-group (500 mg/kg), respectively. No abnormal clinical signs were observed in the survived chickens administrated with KH-502 in the duration of the study. The chickens in positive control groups showed ataxia and incoordination at the 14th day after administration of TOCP. From necropsy, macroscopic changes were not observed in all groups including positive control groups. Histopathologically, oxonal swelling with myelin loss, focal gliosis, distention around axonal space were observed in the spinal cords of the chickens administrated with TOCP 1000 mg/kg. The lesions were distinct in the dorsal and lateral funiculi of cervical spinal cord, in the lateral and ventral funiculi of thoracic spinal cord and in ventral funiculi of lumbosacral spinal cord. Axonal swelling and mlcrogliosis were infrequently observed in the chickens of other groups including negative control one. However, they were nonspecifically distributed in the spinal cords. In this study, we concluded that the new chemical, KH-502 did not have acute delayed neurotoxicity in White Leghorn hens.

• The Korean Journal of Zoology
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• v.33 no.4
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• pp.454-460
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• 1990

The effed of acrylamide on the nervous system has heen morphologically studied using light and electron microscopes. The light micrographs on central and pedpheral nervous tissues of mouse treated with acrylamide monomer showed total vacuolation of spinal cord, cell degradation containing neuron and neuroglia, and distal nerve fiber degeneration. The electron micrographs showed ultrastrudural changes. Abnormal mitochondria in neuron, splitting of myelin sheath in lumbar ventral root nerve, partial disintergration of myelin sheath and axoplasmic degeneration in sciatic nerve, and overafl polyneuropathies in nervous system were observed. These results suggest that acrylarnide intoxicated mouse shows distal behavioral neuropathy as an earlist clinical sign, but the initial effect of acrylamide on the nervous system seems to appear at nearly the same time in both central and peripheral nervous systems.

• Journal of Korean Medicine Rehabilitation
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• v.20 no.4
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• pp.1-15
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• 2010

Objectives : This study was performed to evaluate the effects of Hwangryunhaedok-tang(Huanglianjiedu-tang HHT) water extract on locomotor dysfunction induced by spinal cord injury(SCI) in rats. Methods : SCI was induced by mechanical contusion following laminectomy of 10th thoracic vertebra in Sprague-Dawley rats. HHT was orally given once a day for 14 days after SCI. Neurological behavior was examined with the Basso-Beattie-Bresnahan locomotor rating scale. Tissue damage and nerve fiber degeneration were examined with cresyl violet and luxol fast blue staining. Using immunohistochemisty, cellular damage to neurons and nerve fibers were examined against Bax and MAP-2. As inflammatory response markers, iNOS and COX-2 expressions were also examined. Results : 1. HHT ameliorated the locomotor dysfunction of the SCI-induced rats. 2. HHT attenuated the reduction of motor neurons in the ventral horn of the SCI-induced rat spinal cord. 3. HHT significantly reduced the number of Bax positive cells in the peri-lesion of the SCI-induced rat spinal cord. 4. HHT attenuated the reduction of MAP-2 positive cells in the peri-lesion of the SCI-induced rat spinal cord. 5. HHT significantly reduced the number of iNOS and COX-2 positive cells in the peri-lesion of the SCI-induced rat spinal cord. Conclusions : These results suggest that HHT improves the locomotor dysfunction of SCI by protecting motor neurons from cell death through anti-inflammatory effect.

• The Korean Journal of Physiology
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• v.21 no.1
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• pp.67-77
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• 1987

Effect of intravenously injected clonidine on the flexion reflex was studied in 15 decerebrated and spinalized cats. The flexion reflex was elicited by electrical stimulation of the tibial nerve or the common peroneal nerve and it was recorded as single unit activity from filaments of the L6 or L7 ventral roots. In order to obtain the late flexion reflex discharges, $A{\delta}$ and C afferent fibers were stimulated with single or train electrical pulses respectively. The flexion reflex, especially the late component, was markedly inhibited after intravenous administration of clonidine. The clonidine-induced inhibition of the flexion reflex was compared before and after treatment of the animals respectively with yohimbine and naloxone. The inhibitory effect on the flexion reflex of clonidine was not altered by naloxone, a ${\mu}-opioid$ receptor blocker, whereas it was completely blocked by yohimbine, an ${\alpha}_2-adrenergic$ antagonist. These results indicate that clonidine inhibits the flexion reflex through excitation of ${\alpha}_2-adrenoceptors$ even at the spinal cord level.

• Biomedical Science Letters
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• v.26 no.3
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• pp.217-225
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• 2020

Scuttle fly which moves abruptly after standing for a while and stop suddenly to rush off again, is a fly species in the Phoridae family. This species like rotten organic materials and it is known to proliferate even in the industrial materials including organic solvents. These characteristic behaviors of the scuttle fly seem to be related to muscular and nervous system or neurotransmitters. Thus, we focused at the neurotransmitter, corazonin (Crz) that is known to be related to resistance to stress and investigated the developmental process of the neurons in the scuttle fly. Corazonin is a neuropeptide being expressed in the central nervous system (CNS) and is known to control mainly physiological functions and behaviors. Its many functions that have been proposed are still in controversy. In this studies, we found that there are three groups of corazoninergic neurons in the larval CNS of the scuttle fly and these neurons undergo distinguishable changes through metamorphic process compared to different fly species. Larva has 3 pairs of Crz neurons at the dorsolateral area of the brain, 1 pair at the dorsomedial brain and 8 pairs at the ventral nerve cord.