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Kothandaraman N, Bajic VB, Loganath A, Koh S, Ng J, Choolani M, Razvi K. Early detection of epithelial ovarian cancer using a proteomics-based protein-profiling approach combined with a novel selection strategy. ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2004; 33:S59-60. [PMID: 15651211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
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Kok J, Tan KH, Koh S, Cheng PS, Lim WY, Yew ML, Yeo GSH. Antenatal use of a novel vaginal birth training device by term primiparous women in Singapore. Singapore Med J 2004; 45:318-23. [PMID: 15221047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
INTRODUCTION To study the use, safety and effectiveness of a novel antenatal vaginal birth training device (EPI-NO) in primiparous women. METHODS Antenatal use of the EPI-NO vaginal birth trainer was prospectively studied in 31 primiparous booked patients who were delivered by obstetricians from July to December 2002 at the KK Women's and Children's Hospital. This was studied in relation to episiotomy rate, perineal trauma and analgesic requirements during the postpartum period. A patient questionnaire form was used to assess their perception of pain and how well they coped with its use. For comparison, perineal trauma was also studied retrospectively in 60 consecutive obstetrician-booked primiparous term patients who had normal vaginal delivery (NVD) and who did not use EPI-NO during the same study period. RESULTS The mean length of usage was for 2.1 weeks (standard deviation [sd] 1.2 weeks). The mean frequency of use was 5.3 episodes per week (sd 2.1, range 1 to 7). There was no laceration and vaginal infection arising from its usage. There was a case of minimal bleeding post-usage. There were 20 (64.5 percent) NVDs, four (12.9 percent) forceps deliveries, five vacuum deliveries (16.1 percent) and two (6.5 percent) Caesarean sections. Of the 29 vaginal delivery cases, 19 (65.5 percent) had episiotomy, eight (27.6 percent) had lacerations, and two (6.9 percent) did not sustain laceration. The reasons for episiotomy in the 19 cases were nine cases of pending tearing of vagina/perineum, nine cases of instrumental vaginal deliveries, and one to shorten second stage. There was no third degree tear. 21 (67.7 percent) out of 30 required a painkiller. The majority of patients (17; 54.8 percent) appeared to be comfortable with the use of EPI-NO. All coped well with vaginal examination after using EPI-NO perineal training. Comparing among term primiparous NVD cases with (n value equals 20) and without (n value equals 60) EPI-NO, the perineal trauma rate (90.0 percent vs 96.6 percent, p value equals 0.24) was slightly but not significantly lower in the EPI-NO group. The episiotomy rate was significantly lower (50.0 percent vs 93.3 percent, p value is less than 0.0001) and the extent of perineal trauma in the patient appeared to be less severe in cases using EPI-NO. CONCLUSION EPI-NO appeared to be safe and acceptable to the majority of users. Although birth training with EPI-NO significantly decreases the rate of episiotomies in term primiparous patients, and the degree of perineal tissue injury appeared to be less in the EPI-NO group especially among those with lacerations, the overall perineal trauma rate was slightly but not significantly lower, in view of the higher spontaneous laceration rate in the EPI-NO group.
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Kim J, Koh S, Kim YH, Park E, Yun JH, Kim IH, Kim C, Bornzin G. P-477 Longitudinal trend in abnormal breathing and heart rate variability for patients with heart failure. Europace 2003. [DOI: 10.1016/eupace/4.supplement_2.b178-c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Tomiyama K, Ishida H, Miyake M, Taki T, Koh S, Okuno T. [Surgically treated mucoepidermoid carcinoma in a 6-year-old boy; report of a case]. KYOBU GEKA. THE JAPANESE JOURNAL OF THORACIC SURGERY 2003; 56:505-8. [PMID: 12795159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
A 6-year-old boy was admitted to our hospital with a history of recurrent obstructive pneumonia and hemoptysis. A chest computed tomography (CT) showed atelectasis in the left lower lobe. Angiograpy, which was performed for the suspicion of pulmonary sequestration, showed no feeding artery and revealed bleeding from the bronchial artery in the left lower lobe. As hemoptysis would not stop, an emergency left lower lobectomy was performed. Macroscopic examination of the resected specimen revealed a mass measuring 20 x 15 x 17 mm in the S8 proximal lung parenchyma, bronchiectasis, and an abscess in the distal lung parenchyma. Histopathologic examination determined the tumor was a mucoepidermoid carcinoma. Immunohistochemical staining revealed some tumor cells were positive for CA 19-9. The child has not had a recurrence 3 years postoperatively.
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Horii E, Nakamura R, Koh S, Inagaki H, Yajima H, Nakao E. Surgical treatment for chronic radial head dislocation. J Bone Joint Surg Am 2002; 84:1183-8. [PMID: 12107319 DOI: 10.2106/00004623-200207000-00014] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND The treatment of chronic radial head dislocation remains controversial. High rates of redislocation and complications have been reported after surgery. In our view, correction of malalignment with ulnar osteotomy is the key to a good surgical result. METHODS Since 1975, twenty-two patients were treated surgically for chronic radial head dislocation at our hospital. The procedure consisted of open reduction of a dislocated radial head followed by radial and/or ulnar osteotomy, with or without reconstruction of the annular ligament or by reconstruction of the annular ligament alone. The ages of the patients ranged from four to twenty years. In 1991, we modified the surgical technique by performing an oblique ulnar osteotomy with angulation and elongation and rigid plate fixation. Bone-grafting at the osteotomy site was also performed if necessary. A cast was applied with the forearm in neutral rotation and was worn for two to four weeks. Nine patients were treated with this modified technique. RESULTS The mean interval between the initial injury and the reconstructive surgery was ten months. There were no serious surgical complications. Of the thirteen patients treated before 1991, four had a good reduction and seven had redislocation. Seven patients had restricted forearm rotation postoperatively. Of the nine patients treated with the modified osteotomy since 1991, seven had a good reduction. Two patients, who had had slight radial head deformity preoperatively, had subluxation postoperatively. Two patients had restricted forearm rotation. CONCLUSIONS Since we modified our technique for ulnar osteotomy, good reduction of the radial head has been achieved without causing serious contracture. Both angulation and elongation of the ulna are required to allow the radial head to reduce.
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Koh S, Storey TW, Santos TC, Mian AY, Cole AJ. Early-life seizures in rats increase susceptibility to seizure-induced brain injury in adulthood. 1999. Neurology 2001; 57:S22-8. [PMID: 11775605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
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Sanchez RM, Koh S, Rio C, Wang C, Lamperti ED, Sharma D, Corfas G, Jensen FE. Decreased glutamate receptor 2 expression and enhanced epileptogenesis in immature rat hippocampus after perinatal hypoxia-induced seizures. J Neurosci 2001; 21:8154-63. [PMID: 11588188 PMCID: PMC6763879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2001] [Revised: 06/05/2001] [Accepted: 07/26/2001] [Indexed: 02/21/2023] Open
Abstract
Hypoxic encephalopathy is the most common cause of neonatal seizures and can lead to chronic epilepsy. In rats at postnatal days 10-12 (P10-12), global hypoxia induces spontaneous seizures and chronically decreases seizure threshold, thus mimicking clinical aspects of neonatal hypoxia. We have shown previously that the acute and chronic epileptogenic effects of hypoxia are age-dependent and require AMPA receptor activation. In this study, we aimed to determine whether hypoxia-induced seizures and epileptogenesis are associated with maturational and seizure-induced changes in AMPA receptor composition and function. Northern and Western blots indicated that glutamate receptor 2 (GluR2) mRNA and protein expression were significantly lower in neocortex and hippocampus at P10-12 compared with adult. After hypoxia-induced seizures at P10, GluR2 mRNA was significantly decreased within 48 hr, and GluR2 protein was significantly decreased within 96 hr. AMPA-induced Co(2+) uptake by neurons in hippocampal slices indicated higher expression of Ca(2+)-permeable AMPA receptors in immature pyramidal neurons compared with adult. In slices obtained 96 hr after hypoxia-induced seizures, AMPA-induced Co(2+) uptake was significantly increased compared with age-matched controls, and field recordings revealed increased tetanus-induced afterdischarges that could be kindled in the absence of NMDA receptor activation. In situ end labeling showed no acute or delayed cell death after hypoxia-induced seizures. Our results indicate that susceptibility to hypoxia-induced seizures occurs during a developmental stage in which the expression of Ca(2+)-permeable AMPA receptors is relatively high. Furthermore, perinatal hypoxia-induced seizures induce increased expression of Ca(2+)-permeable AMPA receptors and an increased capacity for AMPA receptor-mediated epileptogenesis without inducing cell death.
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Abstract
Neonatal seizures caused by hypoxia can be refractory to conventional anticonvulsants. Currently, there is no effective postnatal intervention for newborn infants with hypoxic encephalopathy to prevent brain injury and long-term neurologic sequelae. We previously developed a rat model of perinatal hypoxia-induced seizures with subsequent long-term increases in seizure susceptibility and showed that these epileptogenic effects are selectively blocked by the alpha-amino-3-hydoxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor antagonist 6-nitro-7-sulfamoylbenzo(f)quinoxaline-2,3-dione. Using this model of perinatal seizures, we evaluated the efficacy of topiramate, a structurally novel anticonvulsant drug recently shown to attenuate AMPA/kainate currents. Topiramate effectively suppressed acute seizures induced by perinatal hypoxia in a dose-related manner with a calculated ED50 of 2.1 mg/kg, i.p. Furthermore, in animals that had seizures suppressed by topiramate during acute hypoxia, there were no long-term increases in susceptibility to kainate-induced seizures and seizure-induced neuronal injury. Our results suggest that topiramate may have clinical potential as a therapeutic agent for refractory seizures in human neonates.
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Yamazaki M, Koh S. [Spirochetal infection]. RYOIKIBETSU SHOKOGUN SHIRIZU 2001:395-7. [PMID: 11212756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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Duchowny M, Jayakar P, Koh S. Selection criteria and preoperative investigation of patients with focal epilepsy who lack a localized structural lesion. Epileptic Disord 2000; 2:219-26. [PMID: 11174153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Children with medically resistant epilepsy are often referred for surgical evaluation. The absence of a specific focal lesion on MRI may render the work-up difficult. In response to the need to localize the primary area of epileptogenesis, surgery protocols are being developed which rely on clinical semiology, EEG and functional imaging data. In selected cases, intracranial EEG monitoring may be required. While testing more often depends on the convergence of modalities, it is possible to localize seizure origin in the majority of children, and fully excise the epileptogenic region. This review presents the etiology and preoperative modalities available for children with intractable, non-lesional epilepsy.
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Chen WN, Oon CJ, Leong AL, Koh S, Teng SW. Expression of integrated hepatitis B virus X variants in human hepatocellular carcinomas and its significance. Biochem Biophys Res Commun 2000; 276:885-92. [PMID: 11027564 DOI: 10.1006/bbrc.2000.3562] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hepatitis B virus X protein (HBX) has been implicated in the transactivation of diverse cellular genes and possibly also the pathogenesis of human hepatocellular carcinoma (HCC). We report the characterization of HBX variants from HBV-related human hepatocellular carcinoma (HCC). These HBX variants were integrated into the host chromosomes and also expressed in the HCC tissues. In addition, we report a novel in vitro HBX activity assay based on color changes that were indicative of the beta-galactosidase enzyme activity. Conducted in wheat germ lysates, the transactivating function of either wild type or mutant HBX protein was measured through their interaction with the Early Growth Response factor 1 (Egr-1) that controls the beta-galactosidase gene. Further analysis of these HBX deletion mutants using this assay may shed new insights on the significance of various mutations occurring in HCC-associated HBX.
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Koh S, Jayakar P, Dunoyer C, Whiting SE, Resnick TJ, Alvarez LA, Morrison G, Ragheb J, Prats A, Dean P, Gilman J, Duchowny MS. Epilepsy surgery in children with tuberous sclerosis complex: presurgical evaluation and outcome. Epilepsia 2000; 41:1206-13. [PMID: 10999561 DOI: 10.1111/j.1528-1157.2000.tb00327.x] [Citation(s) in RCA: 173] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE Children with tuberous sclerosis complex (TSC) benefit from excisional surgery if seizures can be localized to a single tuber. We evaluated the role of noninvasive studies to localize the epileptogenic tuber/region (ET/R) and the outcome of focal resection. METHODS We identified 21 children with TSC, ages 3 months to 15 years (mean 4.8 years). All had video-(electroencephalogram) EEG and magnetic resonance imaging (MRI) scans, and 18 also had ictal single photon emission-computed tomography (SPECT) studies. An ET/R was localized in 17 patients. Thirteen patients underwent resection guided by intraoperative electrocorticography (n = 7) or subdural monitoring (n = 6). RESULTS Interictal EEG revealed a principal spike focus (PSF) that corresponded to the ET/R in 14 children. In seven, PSFs occurred in rhythmic runs. PSFs were not observed remote from the ET/R. Focal polymorphic slowing and attenuation occurred in the region of the PSF in 11 patients. Sixteen patients demonstrated an ictal focus corresponding to the ET/R. Ictal SPECT revealed focal hyperperfusion correlating with the ET/R in 10 patients. Although the MRIs in all children revealed multiple tubers, the ET/R corresponded to a large discrete tuber in 8 patients and a calcified tuber in 13 patients. Patchy calcified tubers were also seen elsewhere in six patients. At a mean follow-up of 26 months, 9 of the 13 children who underwent surgery were seizure-free, one had greater than 75% reduction in seizures, two were unchanged, and one was lost to follow-up. New seizures developed in one child from a contralateral tuber. CONCLUSIONS Surgical resection of an ET/R alleviates seizures in most children with TSC and intractable epilepsy. The scalp EEG and MRI help define the ET/R and improve case selection when ictal SPECT is nonlocalizing.
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Lin CM, Koh S, Stacey G, Yu SM, Lin TY, Tsay YF. Cloning and functional characterization of a constitutively expressed nitrate transporter gene, OsNRT1, from rice. PLANT PHYSIOLOGY 2000; 122:379-88. [PMID: 10677431 PMCID: PMC58875 DOI: 10.1104/pp.122.2.379] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/1999] [Accepted: 10/31/1999] [Indexed: 05/18/2023]
Abstract
Elucidating how rice (Oryza sativa) takes up nitrate at the molecular level could help improve the low recovery rate (<50%) of nitrogen fertilizer in rice paddies. As a first step toward that goal, we have cloned a nitrate transporter gene from rice called OsNRT1. OsNRT1 is a new member of a growing transporter family called PTR, which consists not only of nitrate transporters from higher plants that are homologs of the Arabidopsis CHL1 (AtNRT1) protein, but also peptide transporters from a wide variety of genera including animals, plants, fungi, and bacteria. However, despite the fact that OsNRT1 shares a higher degree of sequence identity with the two peptide transporters from plants (approximately 50%) than with the nitrate transporters (approximately 40%) of the PTR family, no peptide transport activity was observed when OsNRT1 was expressed in either Xenopus oocytes or yeast. Furthermore, contrasting the dual-affinity nitrate transport activity of CHL1, OsNRT1 displayed only low-affinity nitrate transport activity in Xenopus oocytes, with a K(m) value of approximately 9 mM. Northern-blot and in situ hybridization analysis indicated that OsNRT1 is constitutively expressed in the most external layer of the root, epidermis and root hair. These data strongly indicate that OsNRT1 encodes a constitutive component of a low-affinity nitrate uptake system for rice.
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Chen WN, Oon CJ, Koh S. Horizontal transmission of a hepatitis B virus surface antigen mutant. J Clin Microbiol 2000; 38:938-9. [PMID: 10722322 PMCID: PMC86257 DOI: 10.1128/jcm.38.2.938-939.2000] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Koh S, Ward SL, Lin M, Chen LS. Sleep apnea treatment improves seizure control in children with neurodevelopmental disorders. Pediatr Neurol 2000; 22:36-9. [PMID: 10669203 DOI: 10.1016/s0887-8994(99)00114-9] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Seizure disorder and sleep apnea are common chronic disorders in children, but the relationship between sleep apnea and seizure control has not been studied in the pediatric population. This retrospective review included nine children with neurodevelopmental disorders who had well-documented sleep apneic episodes and seizure disorders. Seizure frequency was reduced in five patients (56%) in the first 12 months after sleep apnea treatment without changes in their antiepileptic medications. Sleep apnea can be one of the seizure precipitants in children with epilepsy. This study indicates the importance of identifying sleep apnea when treating children with intractable epilepsy, particularly in those who are at high risk.
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Senlamai W, Bebermeyer R, Koh S. Dentistry's role in the management of obstructive sleep apnea. THE JOURNAL OF THE GREATER HOUSTON DENTAL SOCIETY 1999; 71:29-30. [PMID: 10825890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
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Koh S, Storey TW, Santos TC, Mian AY, Cole AJ. Early-life seizures in rats increase susceptibility to seizure-induced brain injury in adulthood. Neurology 1999; 53:915-21. [PMID: 10496246 DOI: 10.1212/wnl.53.5.915] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Early childhood convulsions have been correlated with the finding of subsequent hippocampal neuronal loss and memory impairment in patients with intractable temporal lobe epilepsy. There is little direct evidence, however, that links early seizures with the later development of epilepsy and selective hippocampal neuronal loss. OBJECTIVE To study the long-term effect of early seizures on later seizure-induced neuronal damage and behavior. METHODS We used a "two hit" rat seizure mode in which systemic kainate was used to induce seizures during the second week of life (P15) and again in adulthood (P45). Memory was subsequently tested using a Morris water maze, and brains were examined for histologic evidence of injury. RESULTS Although the first kainate-induced seizure is not associated with detectable injury or cell death, it predisposes animals to more extensive neuronal injury after kainate-induced seizures in adulthood. Moreover, although early-life kainate-induced seizures cause no impairment of spatial learning, animals that have early-life and adult kainate-induced seizures perform significantly worse than those that have seizures only as adults. CONCLUSIONS We concluded that early-life seizures, without causing overt cellular injury, predispose the brain to the damaging effect of seizures later in life.
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Hoang A, Koh S, Bebermeyer R, Johnson C. A review of condensable composite. THE JOURNAL OF THE GREATER HOUSTON DENTAL SOCIETY 1999; 71:15-7. [PMID: 10825885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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Enoki H, Izawa T, Kawahara M, Komatsu M, Koh S, Kyozuka J, Shimamoto K. Ac as a tool for the functional genomics of rice. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1999; 19:605-613. [PMID: 10504582 DOI: 10.1046/j.1365-313x.1999.00549.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
To examine whether the maize autonomous transposable element Ac can be used for the functional analysis of the rice genome, we used Southern blot analysis to analyze the behaviour of Ac in 559 rice plants of four transgenic families through three successive generations. All families showed highly active transposition of Ac, and 103 plants (18.4%) contained newly transposed Ac insertions. In nine of the 12 independent transpositions analyzed, their germinal transmission was detected. Partial sequencing of 99 Ac-flanking sequences revealed that 21 clones exhibited significant similarities with protein-coding genes in databases and four of them matched rice cDNA sequences. These results indicate preferential Ac transposition into protein-coding rice genes. To examine the feasibility of PCR-based screening of gene knockouts in rice Ac plants, we prepared bulked genomic DNA from the leaves of approximately 6000 rice Ac plants and pooled the DNA according to a three-dimensional matrix. Of 14 randomly selected genes, two gene knockouts were identified, and one encoding a rice cytochrome P450 (CYP86) gene was shown to be stably inherited to the progeny. Together, these results suggest that Ac can be efficiently used for the functional analysis of the rice genome.
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Alvarez LA, Dean P, Jayakar P, Duchowny M, Resnick T, Dunoyer C, Koh S. [Epilepsy treatment by vagal stimulation]. Rev Neurol 1999; 29:385-7. [PMID: 10797931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
INTRODUCTION Vagal nerve stimulation is the latest therapeutic modality for the treatment of epilepsy. It consists of a lead implanted in the left vagal nerve which is connected to a subcutaneous stimulator implanted in the left axillary or pectorial region. DEVELOPMENT The stimulator is programmed to intermittently stimulate the vagal nerve throughout the day and a magnet also allows the patient to control the stimulation from the outside. This treatment has been used in patients with intractable partial seizures who are not candidates for epilepsy surgery. The results reported have varied but in general the procedure appears promising with at least 50% of the implanted having over 50% improvement in their seizure frequency and many having complete control without significant side effects. CONCLUSION Further review of the results are still needed to fully determine the true value of this treatment and to identify the subgroups of patients which will benefit the most.
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Koh S, Nelson MD, Kovanlikaya A, Chen LS. Anterior lumbosacral radiculopathy after intrathecal methotrexate treatment. Pediatr Neurol 1999; 21:576-8. [PMID: 10465148 DOI: 10.1016/s0887-8994(99)00040-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Intrathecal chemotherapy with methotrexate or cytosine arabinoside is the standard approach to prophylaxis and treatment of central nervous system leukemia in children. Progressive paraplegia, one of the devastating neurologic complications related to this mode of treatment, has been attributed to spinal cord toxicity. Reported are three children who developed progressive paraparesis after intrathecal methotrexate administration followed by complete or partial recovery. Gadolinium enhancement of anterior lumbosacral spinal nerve roots was demonstrated in all three patients, and an elevation of cerebrospinal fluid immunoglobulin G synthesis was evident in two patients with more severe symptoms. The clinical data suggest that anterior lumbosacral radiculopathy is also a type of neurologic complication associated with intrathecal methotrexate treatment.
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Oon CJ, Chen WN, Lim N, Koh S, Lim GK, Leong AL, Tan GS. Hepatitis B virus variants with lamivudine-related mutations in the DNA polymerase and the 'a' epitope of the surface antigen are sensitive to ganciclovir. Antiviral Res 1999; 41:113-8. [PMID: 10320044 DOI: 10.1016/s0166-3542(99)00007-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lamivudine is a new antiviral agent effective against hepatitis B viral (HBV) infections but can result in virus-drug resistance associated with mutations in the conserved 'YM552DD' motif of the HBV DNA polymerase. Due to their overlapping coding regions in the HBV genome, mutations in the DNA polymerase may result in substitutions in the hepatitis B surface antigen (HBsAg), albeit outside the antigenic 'a' epitope. Here we report the identification of a novel type of lamivudine-related mutations located in both the polymerase (YM552DD-->Y1552DD) and the 'a' epitope of HBsAg (Gly130-->Asp130). The same virus carried a HBsAg Gly145-->Arg145 mutation prior to therapy. Both the wild type HBV and lamivudine-related mutants with the Gly145-->Arg145 HBsAg mutation were suppressed following ganciclovir treatment, indicating a beneficial additive effect of both drugs against different forms of HBV mutants.
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Koh S, Jayakar P, Resnick T, Alvarez L, Liit RE, Duchowny M. The localizing value of ictal SPECT in children with tuberous sclerosis complex and refractory partial epilepsy. Epileptic Disord 1999; 1:41-6. [PMID: 10937131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Although multiple cortical tubers are a hallmark of tuberous sclerosis complex (TSC), seizures often originate from a single tuber, making excisional surgery a therapeutic option for intractable patients. To assess the role of ictal single photon emission computed tomography (SPECT) in defining the epileptogenic tuber, we reviewed videoelectroencephalography (V/EEG) data, magnetic resonance imaging (MRI) and SPECT scans of 15 patients (aged 3 months to 15 years, mean 5.1) with medically resistant partial seizures and TSC. SPECT scans were performed using Tc-99m-hexamethylpropyleneamine oxime (HMPAO) injected within 30 seconds of electrographic seizure onset and were graded on a scale from 1 to 5 (1 weakly perfused, 5 strongly perfused). The scalp EEG revealed localized seizure origin in ten patients; five had concordant hyperperfused SPECT regions consisting of comma-shaped areas surrounding hypoperfused areas in the candidate tuber. Strongly hyperperfused regions (grade 3-5) were noted in two patients whose ictal EEG patterns were characterized by sustained, rhythmic fast activity or spiking. The other five patients had nonlocalizing or poorly sustained ictal EEG patterns; one patient in this group had focal hyperperfusion. Invasive EEG recordings in two patients revealed propagated EEG patterns that correlated with the ictal SPECT findings. These findings indicate a strong correlation between ictal SPECT and ictal scalp EEG, especially when there are sustained rhythmic fast ictal EEG patterns.
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Chan JT, Koh S. Latex hypersensitivity and dentistry. THE JOURNAL OF THE GREATER HOUSTON DENTAL SOCIETY 1999; 70:14-6. [PMID: 10686896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
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75
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Kim JS, Koh S, Shin HJ, Lee DS, Lee SY. Biochemical characterization of a UDP-sugar pyrophosphorylase from Thermus caldophilus GK24. Biotechnol Appl Biochem 1999; 29 ( Pt 1):11-7. [PMID: 9889080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
An extremely thermostable UDP-GlcNAc pyrophosphorylase has been purified from Thermus caldophilus GK24 by chromatographic methods including ion-exchange, hydrophobic interaction, and affinity chromatographies. The specific activity of the enzyme was enriched 41.8-fold, with a recovery of 2%. The molecular mass of the enzyme was 41 kDa by SDS/PAGE and 45 kDa by gel-filtration chromatography. The activity was maximum at 86 degrees C and its half-life at 95 degrees C was 30 min. Its optimum pH was 6.9 in the presence of Mg2+ ions. A biochemical study showed that UDP-GlcNAc pyrophosphorylase activity could be enhanced by fructose 1-phosphate, a precursor of UDP-GlcNAc. The enzyme showed a broad substrate specificity with sugar 1-phosphates, including glucose 1-phosphate, GlcNAc-1-P and xylose 1-phosphate. The enzyme was therefore named UDP-sugar pyrophosphorylase. The N-terminal and internal peptide sequences were determined and compared with known sequences from various sources. It was found that N-terminal sequence is similar to that of UDP-GlcNAc and UDP-glucose pyrophosphorylases from other bacterial sources.
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