• Journal of Korean Neurosurgical Society
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• 제29권11호
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• pp.1429-1436
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• 2000

Objectives : This study was performed in cultured rat hippocampal neurons to investigate the acute electrophysiological features of ionotropic glutamate receptors which act as a major excitatory neurotransmitter in mammalian brain. Method : Glutamate receptor agonists were applied into the bath solution embedding in whole-cell patch-clamp recording of single hippocampal neuron. Results : In voltage-clamped at -60mV and the presence of 1mmol $Mg^{2+}$, extracellulary applied NMDA did not induce any inward current. Both the elimination of $Mg^{2+}$ and addition of glycine in bath, however, elicited a NMDAinduced inward current. $Mg^{2+}$ block current was increased gradually in more negative potentials from -30mV, showing a negative slope in I-V plot with $Mg^{2+}$. Glutamate-induced current represented an outward rectification. A non-NMDA receptor component occupied about 40% of glutamate-induced current in the voltage range of -80mV to +60mV. Conclusion : Present study suggests that glutamate activates acutely the non-NMDA receptors which induces an inward current in the level of resting membrane potential. This makes the membrane potential increase and can activate the NMDA receptors that permit calcium influx against $Mg^{2+}$ block. At the depolarized state of neuron, there may be recovery mechanisms of membrane potential to repolarize irrespective of voltage-dependent potassium channels in the hippocampal neurons.

• Clinical and Experimental Pediatrics
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• 제59권sup1호
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• pp.161-164
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• 2016

Guillain-$Barr{\acute{e}}$ syndrome and acute transverse myelitis manifest as demyelinating diseases of the peripheral and central nervous system. Concurrency of these two disorders is rarely documented in literature. A 4-year-old girl presenting with cough, fever, and an impaired walking ability was admitted to hospital. She had no previous complaints in her medical history. A physical examination revealed lack of muscle strength of the lower extremities and deep tendon reflexes. MRI could not be carried out due to technical problems; therefore, both Guillain-$Barr{\acute{e}}$ syndrome and acute transverse myelitis were considered for the diagnosis. Intravenous immunoglobulin treatment was started as first line therapy. Because this treatment did not relieve the patient's symptoms, spinal MRI was carried out on the fourth day of admission and demyelinating areas were identified. Based on the new findings, the patient was diagnosed with acute transverse myelitis, and high dose intravenous methylprednisolone therapy was started. Electromyography findings were consistent with acute polyneuropathy affecting both motor and sensory fibers. Therefore, the patient was diagnosed with concurrency of Guillain-$Barr{\acute{e}}$ syndrome and acute transverse myelitis. Interestingly, while concurrency of these 2 disorders is rare, this association has been demonstrated in various recent publications. Progress in diagnostic tests (magnetic resonance imaging and electrophysiological examination studies) has enabled clinicians to establish the right diagnosis. The possibility of concurrent Guillain-$Barr{\acute{e}}$ syndrome and acute transverse myelitis should be considered if recovery takes longer than anticipated.

• Archives of Plastic Surgery
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• 제34권3호
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• pp.279-284
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• 2007

Purpose: The vein graft was considered as a useful conduit for nerve defect. But the problem is that it might be collapsed in long vein graft state. A new experimental model using vein graft filled with hyaluronic acid was considered. Methods: Thirty rats were used for the experimental animal. In group I, one side of the femoral nerve was exposed and a segment was removed about 15mm. The neural gap was connected with nerve graft. In group II, the nerve gap was connected with vein graft only. In group III, the nerve gap was connected with vein graft filled with hyaluronic acid. A walking track analysis was made periodically for 2 months and NCV(nerve conduction velocity) was executed at the end of the experiment. And morphologic studies were also done for all groups Results: In a walking track analysis, the toe-spread was widen and the foot-length was lengthened. The recovery of the toe-spread and foot length was checked 2 weeks interval, periodically for two months. The SFI (sciatic function index) was $-52.5{\pm}8.2$ in group I, $-68.1{\pm}4$ in group II, $-55.3{\pm}7.9$ in group III. In electrophysiological study, NCV(nerve conduction velocity) was $26.71{\pm}3.11m/s$ in group I, $17.94{\pm}4.35m/s$ in group II, $25.69{\pm}2.81m/s$ in group III. The functional recovery in group I and III was superior to that the group II statistically(p < 0.05) Under electromicroscopic study, the number of the myelinated axons were $1419.1{\pm}240$ in group I, $921.7{\pm}176.8$ in group II, $1322.2{\pm}318$ in group III. The number of the myelinated axons were much more in group I and III than group II statistically (p<0.05). Conclusion: This study suggested that the vein graft filled with hyaluronic acid is more effective than vein graft only for the conduit of the nerve gap. It was thought that the technique could be used in clinical cases with nerve defects as an alternative method to classical nerve grafts.

• The Korean Journal of Physiology and Pharmacology
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• 제1권6호
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• pp.681-690
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• 1997

Loss of synaptic transmission and accumulation of extracellular $K^+([K^+]_O)$ are the key features in ischemic brain damage. Here, we examined the effects of several $K^+$channel modulators on the early ischemic changes in population spike (PS) and $[K^+]_o$ in the CA1 pyramidal layer of the rat hippocampal slice using electrophysiological techniques. After onset of anoxic aglycemia (AA), orthodromic field potentials decreased and disappeared in $3.3{\pm}0.22\;min$ $(mean{\pm}SEM,\;n=40)$. The hypoxic injury potential (HIP), a transient recovery of PS appeared at $6.0{\pm}0.25\;min$ (n=40) in most slices during AA and lasted for $3.3{\pm}0.43\;min$. $[K^+]_o$ increased initially at a rate of 0.43 mM/min (Phase 1) and later at a much faster rate (12.45 mM/min, Phase 2). The beginning of Phase 2 was invariably coincided with the disappearance of HIP. Among $K^+$ channel modulators tested such as 4-aminopyridine (0.03, 0.3 mM), tetraethylammonium (0.1 mM), NS1619 $(0.3{\sim}10\;{\mu}M)$, niflumic acid (0.1 mM), glibenclamide $(40\;{\mu}M)$, tolbutamide $(300\;{\mu}M)$ and pinacidil $(100\;{\mu}M)$, only 4-aminopyridine (0.3 mM) induced slight increase of $[K^+]_o$ during Phase 1. However, none of the above agents modulated the pattern of Phase 2 in $[K^+]_o$ in response to AA. Taken together, the experimental data suggest that 4-aminopyridine-sensitive $K^+$channels, large conductance $Ca^{2+}-activated$ $K^+$ channels and ATP-sensitive $K^+$ channels may not be the major contributors to the sudden increase of $[K^+]_o$ during the early stage of brain ischemia, suggesting the presence of other routes of $K^+$ efflux during brain ischemia.

• 대한임상검사과학회지
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• 제48권2호
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• pp.144-152
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• 2016

경동맥경화증은 대뇌혈류를 감소시킬 수 있고, 대뇌신경세포의 활성도에 영향을 미칠 수 있다. 저자들은 경동맥스텐트삽입술(carotid-artery stenting, CAS) 후 뇌혈류예비능의 회복이 뇌파의 파워스펙트럼에 미치는 영향을 조사하였다. 우선 19명의 CAS 대상자들을 모집하였다. SPECT의 subtraction imaging과 뇌파를 두 번의 시기에 검사하였다. 두 번의 시기는 CAS 시술 직전과 시술하고 1개월이 지난 시점이었다. EEG는 acetazolamide 주입 전(pre-ACZ EEG)과 주입 후(pre-ACZ EEG)에 기록하였다. 검사를 모두 하지 못했거나 뇌파기록의 질이 분석에 적절하지 못했던 환자를 제외하고 최종적으로 7명의 환자를 대상으로 연구하였다. 저자들은 각각의 대뇌 반구에서 spectral ratio (SR)를 구했다. SR은 빠른파형의 파워스펙트럼 수치를 느린파형의 파워스펙트럼 수치로 나눈 값으로 정의하였다. 또한 저자들은 저자들은 반구간인덱스(inter-hemispheric index of spectral ratio, IHISR)를 이용하여 양쪽 대뇌 반구 사이의 파워스펙트럼 수치를 비교하였고, 파워스펙트럼의 변화와 뇌혈류예비능의 변화 사이의 연관성을 관찰하였다. 총 7명의 환자 중 6명의 환자에서 CAS 시행 후 스텐트를 삽입한 쪽의 뇌혈류예비능이 호전되었다. 편측 경동맥경화증이 있었던 3명의 환자들에서는 모든 환자에서 CAS가 pre-ACZ EEG에서 SR을 증가시켰고, post-ACZ EEG의 IHISR을 증가시켰다. SR과 IHISR의 증가는 뇌혈류예비능의 증가와 연관성이 있었다. 반면에 양쪽 경동맥경화증이 있었던 나머지 환자들의 결과는 복잡한 양상을 띄었다. 경동맥협착증이 한쪽에만 있는 환자에서 pre-ACZ EEG의 SR과 post-ACZ EEG의 IHISR가 CAS를 시술한 후에 뇌혈류예비능의 변화를 평가할 수 있는 유용한 전기생리학적 지표가 될 수 있다는 것을 본 연구의 결과를 통해 알 수 있었다. 그러나 경동맥협착증이 양쪽 모두에 있었던 환자들에서는 결과가 복잡한 양상으로 나타났다. 이는 양쪽 협착이 있는 경우에는 뇌의 혈역학이 복잡하기 때문일 것으로 판단하였다.