Publications by authors named "Hyo Min Lee"

20 Publications

  • Page 1 of 1

Altered communication dynamics reflect cognitive deficits in temporal lobe epilepsy.

Epilepsia 2021 Apr 11;62(4):1022-1033. Epub 2021 Mar 11.

Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada.

Objective: Although temporal lobe epilepsy (TLE) is recognized as a system-level disorder, little work has investigated pathoconnectomics from a dynamic perspective. By leveraging computational simulations that quantify patterns of information flow across the connectome, we tested the hypothesis that network communication is abnormal in this condition, studied the interplay between hippocampal- and network-level disease effects, and assessed associations with cognition.

Methods: We simulated signal spreading via a linear threshold model that temporally evolves on a structural graph derived from diffusion-weighted magnetic resonance imaging (MRI), comparing a homogeneous group of 31 patients with histologically proven hippocampal sclerosis to 31 age- and sex-matched healthy controls. We evaluated the modulatory effects of structural alterations of the neocortex and hippocampus on network dynamics. Furthermore, multivariate statistics addressed the relationship with cognitive parameters.

Results: We observed a slowing of in- and out-spreading times across multiple areas bilaterally, indexing delayed information flow, with the strongest effects in ipsilateral frontotemporal regions, thalamus, and hippocampus. Effects were markedly reduced when controlling for hippocampal volume but not cortical thickness, underscoring the central role of the hippocampus in whole-brain disease expression. Multivariate analysis associated slower spreading time in frontoparietal, limbic, default mode, and subcortical networks with impairment across tasks tapping into sensorimotor, executive, memory, and verbal abilities.

Significance: Moving beyond descriptions of static topology toward the formulation of brain dynamics, our work provides novel insight into structurally mediated network dysfunction and demonstrates that altered whole-brain communication dynamics contribute to common cognitive difficulties in TLE.
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http://dx.doi.org/10.1111/epi.16864DOI Listing
April 2021

Plasmid composition and the chpG gene determine the virulence level of Clavibacter capsici natural isolates in pepper.

Mol Plant Pathol 2020 06 20;21(6):808-819. Epub 2020 Mar 20.

Department of Horticultural Biotechnology, College of Life Sciences, Kyung Hee University, Yongin, South Korea.

The gram-positive bacterial species Clavibacter capsici causes necrosis and canker in pepper plants. Genomic and functional analyses of C. capsici type strain PF008 have shown that multiple virulence genes exist in its two plasmids. We aimed to identify the key determinants that control the virulence of C. capsici. Pepper leaves inoculated with 54 natural isolates exhibited significant variation in the necrosis. Six isolates showed very low virulence, but their population titres in plants were not significantly different from those of the highly virulent isolates. All six isolates lacked the pCM1 plasmid that carries chpG, which has been shown to be required for virulence and encodes a putative serine protease, but two of them, isolates 1,106 and 1,207, had the intact chpG elsewhere in the genome. Genomic analysis of these two isolates revealed that chpG was located in the pCM2 plasmid, and two highly homologous regions were present next to the chpG locus. The chpG expression in isolate 1,106 was not induced in plants. Introduction of chpG of the PF008 strain into the six low-virulence isolates restored their virulence to that of PF008. Our findings indicate that there are at least three different variant groups of C. capsici and that the plasmid composition and the chpG gene are critical for determining the virulence level. Moreover, our findings also indicate that the virulence level of C. capsici does not directly correlate with bacterial titres in plants.
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http://dx.doi.org/10.1111/mpp.12932DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7214350PMC
June 2020

Long-T -suppressed zero echo time imaging with weighted echo subtraction and gradient error correction.

Magn Reson Med 2020 02 10;83(2):412-426. Epub 2019 Sep 10.

Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland.

Purpose: To perform direct, selective MRI of short-T tissues using zero echo time (ZTE) imaging with weighted echo subtraction (WSUB).

Methods: Radial imaging was performed at 7T, acquiring both ZTE and gradient echo (GRE) signals created by bipolar gradients. Long-T suppression was achieved by weighted subtraction of ZTE and GRE images. Special attention was given to imperfections of gradient dynamics, to which radial GRE imaging is particularly susceptible. To compensate for gradient errors, matching of gradient history was combined with data correction based on trajectory measurement. The proposed approach was first validated in phantom experiments and then demonstrated in musculoskeletal (MSK) imaging.

Results: Trajectory analysis and phantom imaging demonstrated that gradient imperfections were successfully addressed. Gradient history matching enabled consistency between antiparallel projections as required for deriving zeroth-order eddy current dynamics. Trajectory measurement provided individual echo times per projection that showed considerable variation between gradient directions. In in vivo imaging of knee, ankle, and tibia, the proposed approach enabled high-resolution 3D depiction of bone, tendons, and ligaments. Distinct contrast of these structures indicates excellent selectivity of long-T suppression. Clarity of depiction also confirmed sufficient SNR of short-T tissues, achieved by high baseline sensitivity at 7T combined with high SNR efficiency of ZTE acquisition.

Conclusion: Weighted subtraction of ZTE and GRE data reconciles robust long-T suppression with fastest k-space coverage and high SNR efficiency. This approach enables high-resolution imaging with excellent selectivity to short-T tissues, which are of major interest in MSK and neuroimaging applications.
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http://dx.doi.org/10.1002/mrm.27925DOI Listing
February 2020

Variability in the Analgesic Response to Ibuprofen Is Associated With Cyclooxygenase Activation in Inflammatory Pain.

Clin Pharmacol Ther 2019 09 29;106(3):632-641. Epub 2019 Apr 29.

Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA.

The mechanisms underlying interindividual variability in analgesic efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) are not well understood. Therefore, we performed pain phenotyping, functional neuroimaging, pharmacokinetic/pharmacodynamic assessments, inflammation biomarkers, and gene expression profiling in healthy subjects who underwent surgical extraction of bony impacted third molars and were treated with ibuprofen (400 mg; N = 19) or placebo (N = 10). Analgesic efficacy was not associated with demographic or clinical characteristics, ibuprofen pharmacokinetics, or the degree of cyclooxygenase inhibition by ibuprofen. Compared with partial responders to ibuprofen (N = 9, required rescue medication within the dosing interval), complete responders (N = 10, no rescue medication) exhibited greater induction of urinary prostaglandin metabolites and serum tumor necrosis factor-α and interleukin 8. Differentially expressed genes in peripheral blood mononuclear cells were enriched for inflammation-related pathways. These findings suggest that a less pronounced activation of the inflammatory prostanoid system is associated with insufficient pain relief on ibuprofen alone and the need for additional therapeutic intervention.
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http://dx.doi.org/10.1002/cpt.1446DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6753944PMC
September 2019

Endovascular Management of Ruptured Middle Colic Artery Aneurysm and Review of the Literature.

Ann Vasc Surg 2019 Aug 22;59:310.e13-310.e16. Epub 2019 Feb 22.

Department of Radiology, Yuseong Sun Hospital, Daejeon, Republic of Korea.

A ruptured aneurysm of the middle colic artery (MCA) is extremely rare, and its etiology and optimal treatment are unclear. Previously, surgical intervention was the treatment of choice for ruptured visceral artery aneurysms. However, owing to recent advances in endovascular techniques, transcatheter arterial embolization has been recommended for the management of even ruptured splanchnic aneurysms in clinically stable patients without evidence of bowel ischemia. We report a case of a ruptured MCA aneurysm in a 52-year-old previously healthy man. Coil embolization was attempted successfully. In addition, 7 previously published cases of ruptured MCA aneurysms successfully treated by endovascular embolization were reviewed.
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http://dx.doi.org/10.1016/j.avsg.2018.12.099DOI Listing
August 2019

A connectome-based mechanistic model of focal cortical dysplasia.

Brain 2019 03;142(3):688-699

Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre and Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.

Neuroimaging studies have consistently shown distributed brain anomalies in epilepsy syndromes associated with a focal structural lesion, particularly mesiotemporal sclerosis. Conversely, a system-level approach to focal cortical dysplasia has been rarely considered, likely due to methodological difficulties in addressing variable location and topography. Given the known heterogeneity in focal cortical dysplasia histopathology, we hypothesized that lesional connectivity consists of subtypes with distinct structural signatures. Furthermore, in light of mounting evidence for focal anomalies impacting whole-brain systems, we postulated that patterns of focal cortical dysplasia connectivity may exert differential downstream effects on global network topology. We studied a cohort of patients with histologically verified focal cortical dysplasia type II (n = 27), and age- and sex-matched healthy controls (n = 34). We subdivided each lesion into similarly sized parcels and computed their connectivity to large-scale canonical functional networks (or communities). We then dichotomized connectivity profiles of lesional parcels into those belonging to the same functional community as the focal cortical dysplasia (intra-community) and those adhering to other communities (inter-community). Applying hierarchical clustering to community-reconfigured connectome profiles identified three lesional classes with distinct patterns of functional connectivity: decreased intra- and inter-community connectivity, a selective decrease in intra-community connectivity, and increased intra- as well as inter-community connectivity. Hypo-connectivity classes were mainly composed of focal cortical dysplasia type IIB, while the hyperconnected lesions were type IIA. With respect to whole-brain networks, patients with hypoconnected focal cortical dysplasia and marked structural damage showed only mild imbalances, while those with hyperconnected subtle lesions had more pronounced topological alterations. Correcting for interictal epileptic discharges did not impact connectivity patterns. Multivariate structural equation analysis provided a mechanistic model of such complex, diverging interactions, whereby the focal cortical dysplasia structural makeup shapes its functional connectivity, which in turn modulates whole-brain network topology.
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http://dx.doi.org/10.1093/brain/awz009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6391612PMC
March 2019

Effect of low-intensity resistance training with heat stress on the HSP72, anabolic hormones, muscle size, and strength in elderly women.

Aging Clin Exp Res 2017 Oct 19;29(5):977-984. Epub 2016 Nov 19.

Exercise Physiology Lab, Department of Physical Education, Graduate School, Korea University, Seoul, Republic of Korea.

Background: Several recent studies have reported that heat stress stimulates the activation of heat shock protein 72 (HSP72), leading to an increase in muscle synthesis. Some studies suggested that low-intensity resistance training combined with heat stress could improve muscle size and strength.

Aim: This study aimed to identify the effect of low-intensity resistance training with heat stress over 12 weeks on the HSP72, anabolic hormones, muscle size, and strength in elderly women.

Methods: The subjects were physically healthy women of 65-75 years, who were randomly assigned to one of three groups: a low-intensity resistance training with heating sheet group (HRT group, n = 8), a moderate-intensity resistance training (RT group, n = 6), and a heating sheet group (HEAT group, n = 7). Computed tomography scans, 1-repetition maximum (1RM), and blood samples were taken pre- and post-training.

Results: The HSP72 did not vary significantly between the different groups and times. The IGF-1 and 1RM had significantly increased in all three groups after the training (respectively, p < 0.05). Moreover, the cross-sectional area (CSA) of the quadriceps showed a significantly greater increase in the HRT group than in the HEAT group (p < 0.05).

Conclusions: We found that low-intensity training with heat stress stimulated the anabolic hormones of elderly women, improving their muscle strength and hypertrophy. We believe that low-intensity training with heat stress is an effective way to prevent muscle atrophy and to improve muscle strength in elderly women.
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http://dx.doi.org/10.1007/s40520-016-0685-4DOI Listing
October 2017

Probing signal phase in direct visualization of short transverse relaxation time component (ViSTa).

Magn Reson Med 2015 Aug 22;74(2):499-505. Epub 2014 Aug 22.

Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.

Purpose: To demonstrate the phase evolutions of direct visualization of short transverse relaxation time component (ViSTa) matches with those of myelin water.

Method: Myelin water imaging (MWI) measures short transverse signals and has been suggested as a biomarker for myelin. Recently, a new approach, ViSTa, has been proposed to acquire short T2* signals by suppressing long T1 signals. This method does not require any ill-conditioned data processing and therefore provides high-quality images. In this study, the phase of the ViSTa signal was compared with the phase of myelin water simulated by the magnetic susceptibility model of hollow cylinder.

Results: The phase evolutions of the ViSTa signal were similar to the simulated myelin water phase evolutions. When fiber orientation was perpendicular relative to the main magnetic field, both the ViSTa and the simulated myelin water phase showed large positive frequency shifts, whereas the gradient echo phase showed a slightly negative frequency shift. Additionally, the myelin water phase map generated using diffusion tensor imaging (DTI) information revealed a good match with the ViSTa phase image.

Conclusion: The results of this study support the origin of ViSTa signal as myelin water. ViSTa phase may potentially provide sensitivity to demyelination.
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http://dx.doi.org/10.1002/mrm.25416DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4336851PMC
August 2015

Aspiration pneumonia caused by fentanyl-induced cough -a case report-.

Korean J Anesthesiol 2013 Sep 25;65(3):251-3. Epub 2013 Sep 25.

Department of Anesthesiology and Pain Medicine, Hallym University College of Medicine, Anyang, Korea.

Although fentanyl-induced cough is generally transient and benign, it can give rise to serious problems in patients to whom increasing intracranial, intraocular or intraabdominal pressures may create dangerous situations. This case demonstrates aspiration pneumonia as a complication, exhibiting severe cough induced by intravenous injection of fentanyl.
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http://dx.doi.org/10.4097/kjae.2013.65.3.251DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3790037PMC
September 2013

Mepivacaine-induced contraction involves phosphorylation of extracellular signal-regulated kinase through activation of the lipoxygenase pathway in isolated rat aortic smooth muscle.

Can J Physiol Pharmacol 2013 Apr 2;91(4):285-94. Epub 2013 Jan 2.

Department of Anesthesiology and Pain Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea.

Mepivacaine is an aminoamide local anesthetic with an intermediate duration that intrinsically produces vasoconstriction both in vivo and in vitro. This study investigated the arachidonic acid metabolic pathways involved in mepivacaine-induced contraction, and elucidated the associated cellular mechanism with a particular focus on extracellular signal-regulated kinase (ERK) in endothelium-denuded rat aorta. Isolated rat thoracic aortic rings were suspended for isometric tension recording. Cumulative mepivacaine concentration-response curves were generated in the presence or absence of the following inhibitors: quinacrine dihydrochloride, nordihydroguaiaretic acid, phenidone, AA-861, indomethacin, NS-398, SC-560, fluconazole, PD 98059, and verapamil. Mepivacaine-induced ERK phosphorylation, 5-lipoxygenase (5-LOX) expression, and cyclooxygenase (COX)-2 expression in rat aortic smooth muscle cells were detected by Western blot analysis in the presence or absence of inhibitors. Mepivacaine produced tonic contraction in isolated endothelium-denuded rat aorta. Quinacrine dihydrochloride, nordihydroguaiaretic acid, phenidone, AA-861, NS-398, PD 98059, and verapamil attenuated mepivacaine-induced contraction in a concentration-dependent manner. However, fluconazole had no effect on mepivacaine-induced contraction. PD 98059, quinacrine dihydrochloride, nordihydroguaiaretic acid, AA-861, phenidone, and indomethacin attenuated mepivacaine-induced ERK phosphorylation. Mepivacaine upregulated 5-LOX and COX-2 expression. These results suggest that mepivacaine-induced contraction involves ERK activation, which is primarily mediated by the 5-LOX pathway and in part by the COX-2 pathway.
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http://dx.doi.org/10.1139/cjpp-2012-0197DOI Listing
April 2013

Tapia's syndrome following cervical laminoplasty -A case report-.

Korean J Anesthesiol 2013 Feb 15;64(2):172-4. Epub 2013 Feb 15.

Department of Anesthesiology and Pain Medicine, College of Medicine, Hallym University, Anyang, Korea.

Tapia's syndrome is the palsy of the 10th and 12th cranial nerves, resulting in ipsilateral paralysis of the vocal cord and tongue. It is a rare complication which is related to the anesthetic airway management and positioning of the patient's head during the surgery. We describe a patient with a postoperative unilateral Tapia's syndrome, after general anesthesia, with uncomplicated endotracheal intubation. The patient's symptoms improved gradually for three months.
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http://dx.doi.org/10.4097/kjae.2013.64.2.172DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3581789PMC
February 2013

Evaluation of the neurological safety of epidurally-administered pregabalin in rats.

Korean J Anesthesiol 2012 Jan 25;62(1):57-65. Epub 2012 Jan 25.

Department of Anesthesiology and Pain Medicine, Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Korea.

Background: The primary site of action of pregabalin, i.e. the α-2-δ subunit of the voltage-dependent calcium channel, is located at the dorsal root ganglion and dorsal horn of the spinal cord. Therefore, the epidural administration of pregabalin could have advantages over oral administration. However, the possibility of its neurotoxicity should be excluded before any attempt at epidural administration. We evaluated the neuronal safety of epidurally-administered pregabalin by observing the sensory/motor changes and examining the histopathology of spinal cord in rats.

Methods: Sixty rats of 180-230 g were divided into three groups; 3 mg of pregabalin dissolved in 0.3 ml saline (group P, n = 20), 0.3 ml 40% alcohol (group A, n = 20), or 0.3 ml normal saline (group N, n = 20) was administered epidurally to the rats in each group. Pinch-toe test, motor function evaluation, and histopathologic examination of vacuolation, chromatolysis, meningeal inflammation, and neuritis were performed at the 1st, 3rd, 7th, and 21st day after each epidural administration.

Results: All rats enrolled in group P, like those in group N, showed neither sensory/motor dysfunction nor any histopathological abnormality over the 3-week observation period. In contrast, in group A, 80% of the rats showed abnormal response to the pinch-toe test and all rats showed decreased motor function during the entire evaluation period. In addition, all histopathologic findings of neurotoxicity were observed exclusively in group A.

Conclusions: The epidurally administered pregabalin (about 15 mg/kg) did not cause any neurotoxic evidence, in terms of both sensory/motor function evaluation and histopathological examination in rats.
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http://dx.doi.org/10.4097/kjae.2012.62.1.57DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3272531PMC
January 2012

Inappropriate elevation of bispectral index values in robot assisted thyroidectomy with electromyographic endotracheal tube -A case report-.

Korean J Anesthesiol 2011 Dec 20;61(6):511-4. Epub 2011 Dec 20.

Department of Anesthesiology and Pain Medicine, College of Medicine, Hallym University, Anyang, Korea.

We report a case of an erroneously elevated bispectral index (BIS) during robot assisted thyroidectomy using an electromyographic endotracheal tube (EMG tube), which is safe and useful for laryngeal electromyographic monitoring. Ten minutes after start of the operation, a sudden increase of BIS value up to 98 was noticed. The BIS values were not decreased to < 65 with supplemental anesthetics. The anesthetic method was changed from total intravenous anesthesia to balanced anesthesia. The BIS sensor and monitor were changed and other models were used. These interventions did not alter BIS values. BIS levels remained between 60 and 70 throughout the main procedure and intermittently increased to the mid-90s without any trace of poor signal quality. At the end of the surgery, the BIS values returned to normal range. The patient did not complain of intraoperative recall. Knowledge of potential interference from the use of an EMG tube must be considered when interpreting BIS.
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http://dx.doi.org/10.4097/kjae.2011.61.6.511DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249575PMC
December 2011

Anomalous great cardiac vein draining into the superior vena cava.

Ann Thorac Surg 2011 Jul;92(1):360

Department of Radiology, Gil Hospital, Gachon University of Medicine and Science, Incheon, Republic of Korea.

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http://dx.doi.org/10.1016/j.athoracsur.2010.12.058DOI Listing
July 2011

Establishment of the korean tolerable daily intake of bisphenol a based on risk assessments by an expert committee.

Toxicol Res 2010 Dec;26(4):285-91

Risk Analysis & Research Division, Food Safety Evaluation Department, National Institute of Food and Drug Safety Evaluation Seoul 122-704, Korea.

Recently, reproductive and neurobehavioral effects of bisphenol A (BPA) have been documented, and thus a review was requested for BPA management direction by the government. Therefore, this study was performed to establish a Korean tolerable daily intake (TDI) for BPA. An expert committee, consisting of specialists in fields such as toxicology, medicine, pharmacology, and statistics, was asked to evaluate BPA health based guidance values (HbGVs) . Although many toxicological studies were reviewed to select a point of departure (POD) for TDI, rat and mouse reproductive studies by Tyl et al. (2002, 2006) , which were performed according to GLP standards and OECD guidelines, were selected. This POD was the lowest value determined from the most sensitive toxicological test. The POD, a NOAEL of 5 mg/kg bw/day, was selected based on its systemic toxicity as critical effects. An uncertainty factor of 100 including interspecies and intraspecies differences was applied to calculate the TDI. According to the evaluation results, a TDI of BPA for Korean was suggested at 0.05 mg/kg bw/day. In addition, the BPA exposure level based on food consumption by the Korean population was estimated as 1.509 μg/kg bw/day, and the HI was evaluated at 0.03 when the TDI of 0.05 mg/kg bw/day was applied. This HI value of 0.03 indicated that hazardous effects would not be expected from BPA oral exposures. Although highly uncertain, further studies on low dose neurobehavioral effects of BPA should be performed. In addition, it is recommended that the 'as low as reasonably achievable' (ALARA) principle be applied for BPA exposure from food packaging materials in newborn infants and children.
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http://dx.doi.org/10.5487/TR.2010.26.4.285DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3834505PMC
December 2010

Residual dizziness after successful repositioning treatment in patients with benign paroxysmal positional vertigo.

J Clin Neurol 2008 Sep 30;4(3):107-10. Epub 2008 Sep 30.

Department of Neurology, School of Medicine, Catholic University of Daegu, Daegu, Korea.

Background And Purpose: Benign paroxysmal positional vertigo (BPPV) is the most common form of vertigo. Although the repositioning maneuver dramatically improves the vertigo, some patients complain of residual dizziness. We evaluated the incidence and characteristics of persistent dizziness after successful particle repositioning and the clinical factors associated with the residual dizziness.

Methods: We performed a prospective investigation in 49 consecutive patients with confirmed BPPV. The patients were treated with a repositioning maneuver appropriate for the type of BPPV. Success was defined by the resolution of nystagmus and positional vertigo. All patients were followed up until complete resolution of all dizziness, for a maximum of 3 months. We collected data on the characteristics and duration of any residual dizziness and analyzed the clinical factors associated with the residual dizziness.

Results: Of the 49 patients, 11 were men and 38 were women aged 60.4+/-13.0 years (mean +/-SD), and 30 (61%) of them complained of residual dizziness after successful repositioning treatment. There were two types of residual dizziness: continuous lightheadedness and short-lasting unsteadiness occurring during head movement, standing, or walking. The dizziness lasted for 16.4+/-17.6 days (range=2-80 days, median=10 days). A longer duration of BPPV before treatment was significantly associated with residual dizziness (p=0.04).

Conclusions: Residual dizziness after successful repositioning was observed in two-thirds of the patients with BPPV and disappeared within 3 months without specific treatment in all cases. The results indicate that early successful repositioning can reduce the incidence of residual dizziness.
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http://dx.doi.org/10.3988/jcn.2008.4.3.107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2686873PMC
September 2008

Effects of repeated seafood consumption on urinary excretion of arsenic species by volunteers.

Arch Environ Contam Toxicol 2010 Jan 24;58(1):222-9. Epub 2009 May 24.

College of Medicine, Chung-Ang University, Seoul, Korea.

Arsenic (As) is a known human carcinogen and widely distributed in the environment. The main route of As exposure in the general population is through food and drinking water. Seafood harvested in Korea contains high-level organoarsenics such as arsenobetaine, arsenocholine, and arsenosugars, which are much less harmful than inorganic arsenics. However, for those who eat large amounts of seafood it is important to understand whether seafood consumption affects urinary levels of inorganic As metabolites such as arsenite, arsenate, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA). In this study we investigated urinary As metabolites (inorganic As, MMA[V], DMA[V]) and some biological indexes such as AST, GSH, GPX, lipid peroxidation, and uric acid in volunteer study subjects (seven males and nine females). Total urinary As metabolites were analyzed by the hydride generation method, followed by arsenic speciation using HPLC with ICP-mass spectrometry. Study subjects refrained from eating seafood for 3 days prior to the first urine collection and then ingested seafood daily for 6 consecutive days. The first voided urine of the morning was collected from each subject the first day of the consecutive 6 days of seafood ingestion but prior to the first seafood meal. The first voided urine of the morning was also collected on days 1, 2, 3, 4, 5, 6, 7, 10, and 14 after seafood ingestion. The daily mean intake of total As was 6.98 mg, comprised of 4.71 mg of seaweed (67%), 1.74 mg of flat fish (25%), and 0.53 mg of conch (8%). We observed a substantial increase in total urinary As metabolites for subjects consuming seafood from day 1, which recovered to control level at day 10. The increase in total urinary As metabolites was attributed to the increase in DMA, which is a more harmful metabolite than organoarsenics. However, no significant changes in response biological indexes were observed. These results suggest that it is necessary to evaluate As metabolism when assessing the exposure to inorganic As and potential chronic health effects of seafood consumption in Korea.
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http://dx.doi.org/10.1007/s00244-009-9333-8DOI Listing
January 2010

Epidemiology of complex regional pain syndrome: a retrospective chart review of 150 Korean patients.

J Korean Med Sci 2008 Oct;23(5):772-5

Department of Anesthesiology and Pain Medicine, Jeju National University College of Medicine, Jeju, Korea.

Complex regional pain syndrome (CRPS) is a chronically painful and disabling disorder. However, no data are available even on the epidemiology of CRPS in Korea. This study was undertaken to retrospectively assess the epidemiologic characteristics of CRPS in 150 consecutive patients at a tertiary chronic pain center from March 2002 to February 2006. Information was obtained regarding patients' demographics, nature of injury, and treatment modalities. Seventy-one percent of patients had CRPS type I. The mean 11-point verbal numerical rating scale score at initial examinations and at the time of study were 8.0 and 5.7, respectively. Thirty-two percent of patients showed no change or increase in pain intensity during follow-up at our pain center. The mean duration of CRPS symptoms prior to our pain center evaluation and prior to the time of study were 27 months and 50 months, respectively. These patients had seen on average 5 different physicians before being referred to our center. This study shows that the majority of CRPS patients were referred to our center after more than 2 yr of symptoms. The clinical implication of such delayed transfer and strategies to avoid this problem are discussed.
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http://dx.doi.org/10.3346/jkms.2008.23.5.772DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2580014PMC
October 2008

Intravascular injection in lumbar medial branch block: a prospective evaluation of 1433 injections.

Anesth Analg 2008 Apr;106(4):1274-8, table of contents

Department of Anesthesiology and Pain Medicine, Samsung Seoul Hospital, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.

Background: The successful outcome and validity of lumbar medial branch block (MBB) are largely dependent on technique accuracy. Intravascular uptake of injectate causes a false-negative response to block and is associated with various possible complications. In the current study, we prospectively evaluated the incidence of, and the factors associated with, intravascular injection during block. In addition, we assessed the efficiencies of generally accepted safety measures, such as preinjection aspiration and intermittent fluoroscopy to avoid intravascular injections.

Methods: We prospectively examined 1433 lumbar MBBs in 456 patients performed by seven physicians. Aspiration test, spot radiography, and contrast injection under real-time fluoroscopic visualization were performed sequentially without repositioning the needle. Incidences of blood flashback and the presence of intravascular contrast spread on spot radiographic images and during real-time fluoroscopy were checked. The factors studied for intravascular injection included physician experience, patient age and sex, needle gauge, and block spinal level.

Results: No specific factors were found to affect the incidence of intravascular uptake during block. The overall incidence of intravascular uptake was 6.1% per nerve block (88/1433), and 30 of these were predicted by preinjection aspiration (sensitivity = 34.1%) and 52 by spot radiography (sensitivity = 59.1%).

Conclusions: The aspiration test with or without spot radiography frequently missed the intravascular uptake of contrast during lumbar MBBs. We strongly advocate the use of real-time fluoroscopy during contrast injection to increase diagnostic and therapeutic value and to avoid possible complications.
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http://dx.doi.org/10.1213/ane.0b013e318162c358DOI Listing
April 2008

Identification of patients with childhood moyamoya diseases showing temporary hypertension after anesthesia by preoperative multifractal Hurst analysis of heart rate variability.

J Neurosurg Anesthesiol 2006 Oct;18(4):223-9

Department of Pediatrics, College of Medicine, Hanyang University, Korea.

Objective: This study was performed to determine whether the preoperative multifractal Hurst analysis of heart rate variability might identify and characterize childhood patients with moyamoya disease (MMD) who showed temporary postoperative hypertension.

Methods: We studied 59 childhood patients with MMD. Thirty were classified as hypertensive group when the mean arterial pressure in the postoperative recovery room was 120% or greater than that during the preoperative period and 29 were classified as normotensive group. The 2 groups were compared with respect to preoperative indices of heart rate variability including frequency-domain measures, approximate entropy, and very short-term multifractal Hurst exponents of RR intervals (RRI). Using preoperative indices that showed significant differences, discriminant analysis was performed to identify postoperative hypertensive patients.

Results: Only exponents of the order > or =3 (H3alpha, H4alpha, and H5alpha) were significantly lower in the hypertensive group than in the normotensive group. Frequency-domain measures, approximate entropy, and the exponents of the order < or =2 were not significantly different in the 2 groups. Discriminant analysis using all of the three exponents correctly identified 27/30 (90%) of the postoperative hypertensive patients.

Conclusions: Preoperative very short-term multifractal Hurst analysis of RRI variability identified 90% of childhood MMD patients who developed postoperative hypertension. The preoperative characteristic of RRI variability was the reduced smoothness at the 8-second-long, local RRI regions within which a very large change of RRI occurs.
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http://dx.doi.org/10.1097/00008506-200610000-00001DOI Listing
October 2006