Yoon Hee Kim

Effects of human neural stem cell transplantation in canine spinal cord hemisection.

Abstract Objectives: Previous works have reported that the transplantation of neural stem cells (NSCs) may improve functional recovery after spinal cord injury (SCI), but these results have been mainly obtained in rat models. In the present work, the authors sought to determine whether the transplantation of human NSCs improves functional outcome in a canine SCI model and whether transplanted NSCs survive and differentiate. Methods: Human NSCs (HB1. F3 clone) were used in this work. Lateral hemisection at the L2 level was performed in dogs and either (1) Matrigel (200 μl) alone as a growth-promoting matrix or (2) Matrigel seeded with human NSCs (107 cells/200 μl) were transplanted into hemisected gaps. Using a canine hind limb locomotor scale, functional outcomes were assessed over 12 weeks. Immunofluorescence staining was performed to examine cell survival, differentiation and axonal regeneration. Results: Compared with dogs treated with Matrigel alone, dogs treated with Matrigel + human NSCs showed significantly better functional recovery (10.3 ± 0.7 versus 15.6 ± 0.7, respectively, at 12 weeks; p<0.05). Human nuclei-positive cells were found mainly near hemisected areas in dogs treated with Matrigel + NSCs. In addition, colocalization of human nuclei and neuronal nuclei or myelin basic protein was clearly observed. Moreover, the Matrigel + NSC group showed more ascending sensory axon regeneration. Conclusions: The transplantation of human NSCs has beneficial effects on functional recovery after SCI, and these NSCs were found to differentiate into mature neurons and/or oligodendrocytes. These results provide baseline data for future clinical applications.

Atorvastatin enhances hypothermia-induced neuroprotection after stroke

BACKGROUNDnBoth statin and hypothermia protect the brain from focal cerebral ischemia. In this study, we sought to determine whether statin pretreatment enhances the efficacy of hypothermia and extends the therapeutic time window of hypothermia.nnnMETHODSnRats were subjected to focal cerebral ischemia for 2 h. Initially, we tested the efficacy of atorvastatin pretreatment (1 mg/kg, daily for 10 days before ischemia) and hypothermia (32-33 degrees C for 2 h at onset of ischemia) in combination, and then we examined the effects of atorvastatin pretreatment on the therapeutic time window of hypothermia (3 or 6 h after ischemia).nnnRESULTSnBoth atorvastatin (27.5+/-4.6) and hypothermia (25.9+/-6.3%) reduced infarct volumes significantly as compared with the control group (40.5+/-3.3%; p<0.05 in each comparison). These two treatments in combination further decreased infarct volumes (13.2+/-6.3%), and remarkably reduced the staining extents of Ox-42, and of inducible nitric oxide synthase. In addition, hypothermia alone was found to be effective when applied at 3 h after ischemia, but not when applied at 6 h. However, atorvastatin pretreatment and hypothermia led to a significant reduction in infarct volumes even when hypothermia was applied at 6 h.nnnCONCLUSIONSnIt was found that atorvastatin pretreatment strongly enhances hypothermia-induced neuroprotection and extends the treatment window after stroke. Because both treatments are already known to be clinically feasible and safe, such a strategy would appear have merits for the treatment of acute stroke.

The effect on respiratory mechanics when using a Jackson surgical table in the prone position during spinal surgery

Background Respiratory dynamics may be monitored and evaluated indirectly by measuring the peak inspiratory pressure and plateau pressure. In this study, the respiratory dynamics of patients undergoing spinal surgery using a Jackson surgical table were observed with a device after converting their position from supine to prone. The effects of the dynamic compliance and airway resistance were observed from the changes in peak inspiratory pressure and plateau. Methods Twenty five patients were selected as subjects scheduled to undergo lumbar spine surgery. After intubation, the patients were ventilated mechanically with a tidal volume of 10 ml/kg and a respiration rate of 10/min. Anesthesia was maintained with sevoflurane 1.5%, nitrous oxide 2 L/min and oxygen 2 L/min. The peak inspiratory pressure, plateau pressure, resistance, compliance, arterial oxygen tension, carbon dioxide tension, heart rate and arterial blood pressure were measured at 10 minutes after the induction of anesthesia. These parameters were measured again 10 minutes after placing the patient in the prone position. Results The prone position did not significantly affect the arterial oxygen tension, carbon dioxide tension, blood pressure and heart rate, but significantly increased the peak inspiratory pressure and resistance and decreased the dynamic compliance. Conclusions The peak inspiratory pressure was increased using a Jackson surgical table to minimize the abdominal pressure when converting from the supine to prone position. This might be due to a decrease in lung and chest compliance as well as an increase in airway resistance.

Sevoflurane Exposure during the Critical Period Affects Synaptic Transmission and Mitochondrial Respiration but Not Long-term Behavior in Mice

Background: Anesthesia during the synaptogenic period induces dendritic spine formation, which may affect neurodevelopment. The authors, therefore, evaluated whether changes in synaptic transmission after dendritic spine formation induced by sevoflurane were associated with long-term behavioral changes. The effects of sevoflurane on mitochondrial function were also assessed to further understand the mechanism behind spinogenesis. Methods: Postnatal day 16 to 17 mice were exposed to sevoflurane (2.5% for 2u2009h), and synaptic transmission was measured in the medial prefrontal cortex 6u2009h or 5 days later. The expression of postsynaptic proteins and mitochondrial function were measured after anesthesia. Long-term behavioral changes were assessed in adult mice. Results: Sevoflurane increased the expression of excitatory postsynaptic proteins in male and female mice (n = 3 to 5 per group). Sevoflurane exposure in male mice transiently increased miniature excitatory postsynaptic current frequency (control: 8.53u2009±u20092.87; sevoflurane: 11.09u2009±u20092.58) but decreased miniature inhibitory postsynaptic current frequency (control: 10.18u2009±u20094.66; sevoflurane: 6.88u2009±u20092.15). Unexpectedly, sevoflurane increased miniature inhibitory postsynaptic current frequency (control: 1.81u2009±u20091.11; sevoflurane: 3.56u2009±u20091.74) in female mice (neurons, n = 10 to 21 per group). Sevoflurane also increased mitochondrial respiration in male mice (n = 5 to 8 per group). However, such changes from anesthesia during the critical period did not induce long-term behavioral consequences. Values are presented as mean ± SD. Conclusions: Sevoflurane exposure during the critical period induces mitochondrial hyperactivity and transient imbalance of excitatory/inhibitory synaptic transmission, without long-lasting behavioral consequences. Further studies are needed to confirm sexual differences and to define the role of mitochondrial activity during anesthesia-induced spine formation.

Difficult back , turns into "less difficult back" by ultrasonography

Despite the accumulation of medical experience, better training, advanced equipment and safer local anesthetics, the incidence of neurological complications after central neuraxial blockade has not decreased [1]. Several explanations have been suggested, including the increased popularity of regional anesthesia as well as the increasing prevalence of risk factors (e.g., obesity [2], diabetes [3], and potent anticoagulant [4]). n nNeurological complications after a central neuroaxial blockade can occur due to non-anesthetic or probable anesthetic causes. Non-anesthetic causes include surgical position, trauma, and compression by tourniquet or casts, etc. Probable anesthetic causes include traumatic injury during needle or catheter insertion, spinal cord ischemia, infection and toxicity of anesthetic drugs. n nAmong the probable anesthetic causes, traumatic injury needs special attention. Needle trauma can easily lead to neurological complications. Multiple traumatic attempts during needle placement are widely known to be related to higher incidence of epidural hematoma [3,5]. The Norwegian Association of Anaesthesiologist guidelines for central neuraxial blockade in patients with potential bleeding problems specifically mention the need for a competent and atraumatic anesthesiologist [3]. Owens et al. [6] reviewed six reports of spinal hematomas after spinal anesthesia. In the five cases for which comments were available, four of the five were termed a difficult tap. n nAlso, multiple needle attempts can cause postdural puncture headaches [7] and is a contributing factor for postoperative back pain [8,9]. It is known to be the main cause of patient dissatisfaction and refusal for additional central neuraxial blocks [10]. n nAccordingly, in order to prevent a less experienced provider from performing a prolonged, traumatic and painful procedure, it is necessary to precisely identify a difficult back. Identification can also provide an opportunity to switch the type of anesthesia in advance. n nAnesthesiologists have long recognized the importance of identifying patients with significant risks prior to treatment, including difficult airways [11], protamine anaphylaxis [12] and malignant hyperthermia [13]. n nHowever, in spite of the risks of severe complications, very few studies evaluate the factors that can potentially cause technical problems when performing a central neuraxial blockade. n nIn the Korean Journal of Anesthesiology, Kim et al. [14] studied 253 patients scheduled for elective surgery under spinal or epidural blockade. Kim et al. [14] evaluated the predictors of a difficult back by using the number of attempts during a neuraxial block as a measure of difficulty. They reported that the depth of the subarachnoid or epidural space and the providers level of experience are related to the difficulty in performing a neuraxial blockade. However, one must consider the method used in order to measure the depth of the subarachnoid or epidural space in the Kim et al. [14] study. Kim et al. [14] measured the depth of the subarachnoid or epidural space by measuring the length from the skin to the needle hub and subtracting this from the total length of the needle. This cannot be considered as an objective measurement. n nFirstly, the approach method was not unified. The authors mentioned that the approach method was not considered due to the point that using only one approach method is not only impractical, but it is also impossible to perform a precise median or paramedian approach in discusssion section. n nAlthough this is somewhat true, the insertion depth would mostly be deeper in the paramedian approach. Furthermore, the insertion depth would mostly be deeper in the paramedian approach. The needle insertion site can also affect the depth of the needle due to the large lumbar interspinous space. The insertion angle of the needle is also important since even a small change in angle can affect the needle trajectory. Different block patterns used by different anesthesiologists can also reduce the objectivity of measurements. n nThe depth of the subarachnoid or epidural space can be measured accurately by MRI or ultrasound with the patient in the same position. Objectivity can be achieved even when measuring with the needle if the needle trajectory is controlled by adjusting the insertion point and angle by ultrasound as shown in the study conducted by Balki et al. [15]. n nIn previous studies that identify factors related to difficult central neuraxial blocks, many researchers regard the quality of anatomical landmarks (related to BMI) and the distance from skin to subarachnoid or epidural space as the predictor of difficulty [16-19]. n nPoor landmark can especially interfere with accurate interspace identification and lead to conus medullaris injury [20-22]. The classical teaching is that the spinal cord ends at L1-2, but it has been known for over half a century that this is the mean position of a normal distribution. Several series describe the spinal cord extending to the body of L3 in 1-3% of patients, and to L2 or lower in almost 50% of patients, with increased variability in women [23]. As suspected by many clinicians, precise lumbar interspace identification by palpation is prone to error. Broadbent et al. [24] confirmed this, showing that anesthetists were 29% accurate, as determined by MRI. n nRecent studies clearly show that ultrasound-guided techniques can reduce the technical difficulty of neuraxial blockade in patients with difficult anatomic landmarks even in the hands of experienced anesthesiologists [25-31]. Although the relatively deep epidural space and interfering bone structures limit the potential of ultrasound-guided epidural puncture, benefits such as the estimation of the depth to the intrathecal or epidural space can be quite useful [32]. Accurate identification of the intervertebral levels may also reduce the risk of conus medullaris injury. n nIn summary, the attempt by Kim et al. [14] to investigate difficulty predictors during central neuraxial block is quite meaningful for a safer and higher quality neuraxial block. We also believe that ultrasonography can definitely help to solve Kim et al.s and our concern.