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Biomedical subjects

S H Chuang

Publications and source records attributed to S H Chuang.

At least 55 records · Page 3Linked to original sources
PubMed2001

Comparison of electroencephalographic dipoles of interictal spikes from prolonged scalp video-electroencephalography and magnetoencephalographic dipoles from short-term recording in children with extratemporal lobe epilepsy.

We retrospectively compared electroencephalographic (EEG) dipoles of interictal spikes from prolonged video-EEG monitoring with magnetoencephalographic dipoles from short-term recording in four children with extratemporal lobe epilepsy. We analyzed both sets of dipoles using individual interictal spikes and single moving dipole modeling and evaluated the profiles of spike appearance, dipole position, and orientation in EEG and magnetoencephalography. We obtained more than 100 magnetoencephalographic spikes in two patients who manifested frequent interictal EEG spikes throughout both day and night but fewer than 40 magnetoencephalographic spikes in two patients who had interictal EEG spikes mainly during sleep. The dipole positions of EEG and magnetoencephalography were in close proximity and included in the surgical resection area. Most of the dipoles between EEG and magnetoencephalography were oriented perpendicularly. A combination of EEG dipole analysis from prolonged video-EEG monitoring and magnetoencephalographic dipole analysis provides complementary information for presurgical evaluation in children with intractable extratemporal lobe epilepsy.

Adolescent↗
PubMed2001

Interaction between 3-(p-tolylamino)-1,5-azulenequinone and the deoxyguanosine residue in various oligonucleotides upon photolysis.

Eight single-stranded oligodeoxyribonucleotides 32P-labeled at the 5'-end were synthesized; they were annealed with the complementary oligodeoxyribonucleotides to form the corresponding double-stranded helices. These duplexes possessed standard Watson-Crick base pairs, locally perturbed sites of a base mismatch, or a bulge. Further, 5'-32P-labeled oligodeoxyribonucleotides with a hairpin loop were also synthesized. Cleavage of these single- and double-stranded oligodexyribonucleotides selectively at the deoxyguanosine residue was accomplished by use of 3-(p-tolylamino)-1,5-azulenequinone 1 upon irradiation with 350 nm UV light. The single strands were cleaved more efficiently than the double-helices. For the helices containing a deoxyguanosine residue at a bulge, at a hairpin loop or toward the end, the cleaving efficiency was increased. Computation results indicate that two possibilities exist for agent 1 to form two "Watson-Crick type" hydrogen bonds with guanine in single-stranded oligodeoxyribonucleotides; yet, only one possibility exists in duplexes.

Base Sequence↗
PubMed2001

The characteristics of phosphorus removal in an anaerobic/aerobic sequential batch biofilter reactor.

Previous research has shown that alternated anaerobic/aerobic conditions are effective in removing phosphorus from wastewater using a biofilter system. However, few studies have been conducted on the features of polyphosphate (poly-P) accumulating organisms (PAOs) in biofilm on phosphorus removal. This study investigated the characteristics of the phosphorus removal mechanism in various hydraulic loads and anaerobic/aerobic time ratios using a sequential batch biofilter reactor. The storage and release of intracellular inclusions, especially polyhydroxyalkanoates (PHAs) and poly-P, would be an important factor for phosphorus removal. Under different operating conditions, total phosphorus removal was always determined by accumulation of PHAs and phosphorus release under the anaerobic phase. The PHA accumulation under the anaerobic phase was always in proportion to the biofilm phosphorus content under aerobic conditions. The result shows PAOs activity was closely related to PHA accumulation. However, the PHA accumulation under the anaerobic phase would be dependent on the hydrolysis of the complex carbon source into short chain fatty acids (SCFA). The result would be demonstrated by the simple carbon source effect. The effect of the An/Ox time ratio on TP removal was significant. Shorter anaerobic time would result in insufficient phosphorus release and greater time would result in inactive PAOs. The appropriate An/Ox time ratio was suggested as 1/2. Comparisons of the phosphorus removal characteristics between biofilm and suspended growth under the same growth conditions are discussed in detail.

Bacteria, Aerobic↗
PubMed1996

Infantile spasms: cerebral blood flow abnormalities correlate with EEG, neuroimaging, and pathologic findings.

This ongoing study examines abnormalities of cerebral perfusion in a consecutive series of children with infantile spasms and correlates cerebral blood flow (CBF) abnormalities with electroencephalographic (EEG), neuroimaging, and pathologic findings. A consecutive series of children with infantile spasms, diagnosed by standard clinical and EEG criteria, had cerebral perfusion studies using 99Tc-HmPAO single photon emission computed tomography (SPECT), together with neuroimaging studies using computed tomography (CT) and/or magnetic resonance imaging (MRI), interpreted independently and correlated with surgical pathologic findings. Twenty children aged 2-13 months (mean 9.3 months) were studied over a 4-year period; 60% had symptomatic infantile spasms due to cerebral dysgenesis (33%), other congenital lesions (25%), tuberous sclerosis (17%), or other causes (25%), and the remaining patients were cryptogenic (40%). CBF abnormalities were present in 85%: multifocal decrease (40%), focal increase (25%), diffuse decrease (15%), and focal increase (10%), while the remaining 15% had normal cerebral blood flow. Focal cortical lesions may lead to infantile spasms, even in cryptogenic patients diagnosed by functional neuroimaging such as 99Tc-HmPAO SPECT. In selected patients, surgical excision of the cortical lesions leads to improved seizure control and possibly outcome. The localization and surgical excision of focal cortical lesions in infantile spasms required further investigation with functional and structural neuroimaging, EEG, and intraoperative electrocorticography.

Brain↗
PubMed1995

Neuroimaging studies in children with temporal lobectomy.

Twenty-eight children with intractable seizures who subsequently underwent a temporal lobectomy were studied by electroencephalogram (EEG), prolonged video EEG telemetry, computed tomography (CT), magnetic resonance imaging (MRI), and single photon emission computed tomography (SPECT) for the localization of epileptogenic foci. MRI showed abnormalities indicating epileptogenic foci in 21/25 patients and a increased signal intensity in 7/11 patients with mesial temporal sclerosis (MTS). SPECT showed corresponding abnormalities in 17/22 patients, including an interictal decrease in regional cerebral blood flow corresponding to the epileptogenic zone in 15. CT showed localized abnormalities in 16/28. All 12 patients with benign, slow-growing neoplasms showed an abnormality on CT scan. In children, MRI is essential in localizing epileptogenic abnormalities, especially MTS and cortical dysplasia. SPECT contributes to the localization of epileptogenic foci, which are often coincident with EEG abnormalities, particularly in single pathology. CT depicts benign neoplasms with calcification in the temporal lobe, which are likely to provoke complex partial seizures.

Adolescent↗
PubMed1995

Pediatric magnetic source imaging.

Magnetic source imaging has changed the perspective of managing pediatric patients with epilepsy since its introduction into clinical imaging in the pediatric population. Magnetic source imaging can be important in understanding pediatric functional neuroanatomy and for epileptic surgery in children with intractable seizures. The use and efficacy of magnetic source imaging for surgical planning and patient management is demonstrated by case reports presented in this article.

Brain Mapping↗
PubMed1993

Comparison of sedation regimens for pediatric outpatient CT.

The purpose of this study was to compare the concurrent use of chloral hydrate (CH), intramuscular Nembutal (IMN) and intravenous Nembutal (IVN) for sedation. Data was collected on all pediatric outpatients requiring sedation for CT over a 2.5-year period. During this period, 2178 outpatients required sedation of whom, 1324 (60.8%) received IMN, 710 (32.6%) IVN and 110 (5%) CH. The overall success rate was 97% and was similar in all three groups. IVN however, produced better-quality sedation than IMN or CH. The IVN group received a significantly lower dose of Nembutal than the IMN group (p = 0.001). Patients receiving IVN had a significantly lower induction time (p = 0.0001) and total examination time (p = 0.001) than IMN or CH. There was an increased occurrence of desaturation in patients sedated with IVN, especially in those with airway obstruction. IVN sedation permits faster, more efficient and better-quality sedation for outpatient CT scanning than IMN or CH in patients requiring intravenous contrast but may not be appropriate for departments that perform relatively few sedations or lack proper resuscitation facilities.

Ambulatory Care↗
PubMed1993

Bilateral basal ganglia lesions: pediatric differential considerations.

Computed tomography (CT) and magnetic resonance (MR) imaging have dramatically improved the ability to visualize the deep gray structures of the basal ganglia (primarily, the caudate nucleus, putamen, and globus pallidus). Any process that alters cerebral metabolism can lead to basal ganglia damage. This article presents the spectrum of disease that may be seen with bilateral basal ganglia abnormalities in the pediatric population. A simplified approach to the differential diagnosis of these entities is based on acute versus chronic conditions and radiologic manifestations. Acute processes include hypoxia, hypoglycemia, carbon monoxide poisoning, hemolytic-uremic syndrome, osmotic myelinolysis, and encephalitis. Chronic conditions include inherited ("inborn errors of metabolism," Huntington disease, and dysmyelinating diseases) or acquired (sequelae of acute disorders) conditions that represent abnormal biochemical or structural processes within the basal ganglia. Elimination of acute causes gives little hope for improvement. Recognition of chronic disorders is important for counseling purposes, since most of these conditions have specific patterns of inheritance.

Acute Disease↗
PubMed1992

Detection and management of gangliogliomas in children.

Forty-two children treated for gangliogliomas were reviewed to identify the best methods of detection and management. Thirty-two of the tumors were supratentorial, four infratentorial, and six were in the spinal cord. Twenty-five patients presented with seizures; the mean duration of symptoms was 5 years in contrast to 1 year in non-seizure patients. Of 31 children studied by computed tomography (CT), calcification in the tumor lesion was found in 19. Magnetic resonance imaging (MRI) showed abnormal high-signal intensity on T2 imaging in six of eight patients. All patients underwent surgical resection and were diagnosed pathologically. Twenty-four patients had total resection, and 14 underwent temporal lobectomies including hippocampectomy. The management of this tumor remains surgical resection without the need for any adjuvant therapy.

Adolescent↗
PubMed1992

Neuroimaging for investigation of seizures in children.

In patients with structural abnormalities of the brain with poor seizure control by medication, epilepsy surgery becomes a very important tool for seizure control. Numerous radiological imaging studies are being used for studying the abnormality in order to aid in the planning of surgery. Included in the radiological imaging modalities are CT, MR, and Xenon CT, SPECT and PET. In future, perfusion and diffusion MR as well as MEG mapping will become part of the investigative tool. The following paper is a summary and discussion of the usefulness of different modalities in different disease entities with a proposal for the method of investigation.

Brain Damage, Chronic↗
PubMed1990

Unilateral megalencephaly associated with neonatal high output cardiac failure.

High-flow cerebral arteriovenous fistulae are well known to present in the neonatal period with macrocephaly, cranial bruits and high-output cardiac failure. This report describes a newborn infant with such a clinical presentation, who had unilateral megalencephaly without macroscopic arteriovenous shunts. Ultrasound Doppler examination of the carotid and cerebral vessels showed diastolic flow, or a decreased pulsatility index, consistent with decreased intracranial vascular resistance. The ipsilateral cerebral arteries and veins were markedly enlarged at angiography and at post-mortem examination, but there was no arteriovenous malformation. The infant expired from high-output cardiac failure and hypoglycemia. It is postulated that the high-output cardiac failure was due to increased blood flow through the enlarged, dysplastic cerebral hemisphere.

Brain↗
PubMed1990

Unilateral megalencephaly: correlation of MR imaging and pathologic characteristics.

Unilateral megalencephaly is a rare and poorly understood malformation resulting in the enlargement of all or part of a cerebral hemisphere. The clinical and radiologic features of 12 patients with unilateral megalencephaly are presented; pathologic correlation was available in four. All patients had seizures and developmental delay. Two were in congestive heart failure as a result of arteriovenous shunting through the abnormal hemisphere. The affected hemispheres showed a wide spectrum of involvement. Anomalies of neuronal migration were present, and there was a roughly inverse correlation between the severity of hemispheric involvement and the magnitude of enlargement. This correlation is explained via a proposed mechanism of a mild hemispheric insult in the middle-to-late second trimester. One patient had an extremely anomalous hemisphere that did not have characteristics of a neuronal migration anomaly and may have been a hamartomatous malformation. Our correlation of the clinical, radiologic, and pathologic features of unilateral megalencephaly, together with a theory of pathogenesis, should help elucidate this rare malformation.

Adolescent↗
PubMed1989

Computed tomography in intracranial, supratentorial metastases in children.

This study compares the CT characteristics in a consecutive sample of supratentorial metastases (n = 31) with primary tumors of the same location (n = 49) in childhood. Postcontrast CT was performed in all but one of the metastases cases. In all but one of these children the location and type of primary tumor was known at time of occurrence of cerebral metastasis. Primary CNS tumors (n = 12) had a higher incidense of supratentorial metastatic spread than tumor originating elsewhere. Three children had diffuse subarachnoid seeding, while 28 had solid tumors (21 solitary, 7 multiple). The predilection location for the solid metastases was the gray-white matter junction (n = 12). The following CT findings were significantly less frequent in metastases than in primary tumors (P less than 0.05): Midline location, calcification and cyst formation. On the other hand bleeding, pronounced contrast enhancement and location in the gray-white matter junction were more frequent in the metastatic group (P less than 0.05).

Brain Neoplasms↗
PubMed1988

MR of neuronal migration anomalies.

Migration anomalies are congenital malformations caused by insults to migrating neuroblasts during the third to fifth gestational months. Included in this group are agyria, pachygyria, polymicrogyria, unilateral megalencephaly, schizencephaly, and gray matter heterotopias. Patients who have these conditions present clinically with developmental delay and seizures, and abnormal motor skills are noted in the more severely affected infants. To determine the utility of MR as a method for imaging in these patients, we used MR to evaluate 13 patients who had the full spectrum of migration anomalies. MR was more sensitive than CT in detecting these anomalies because of its better contrast between gray and white matter. We found that MR was particularly more sensitive in detecting schizencephaly, where recognizing the presence of gray matter lining the cleft is critical to distinguishing that disease from porencephaly, and in detecting polymicrogyria, where critical details of cortical architecture are obscured on CT by the overlying bone. Multiplanar capabilities were also found to be essential, since narrow clefts may not be detected when the imaging plane is parallel to the cleft. MR should be the primary imaging method for infants who have seizures or developmental delay.

Adolescent↗
PubMed1988

Sonographic evaluation of spinal cord birth trauma with pathologic correlation.

Birth trauma to the spinal cord is a serious potential complication of delivery. Determining the presence, severity, and extent of injury poses a difficult problem because of the often confusing clinical setting. Myelography has been recommended for assessing spinal cord birth trauma but is invasive and may not be helpful. The role of sonography in evaluating spinal cord birth trauma has not been previously described. We assessed the value of sonography in four patients, three of whom also had CT metrizamide myelography. Autopsy correlation was available in three patients. Sonography was able to easily demonstrate the cord configuration, allowing for multiple assessments over time. Internal cord echogenicity was helpful in a case of hematomyelia and in demonstrating the changes of myelomalacia. Sonography is useful in evaluating neonates with severe spinal cord injury; it obviates the need for myelography and also may allow less severely injured patients to be assessed more frequently.

Birth Injuries↗
PubMed1985

Microsurgical recovery of a migrated balloon from the internal carotid artery of a child.

A child developed a traumatic intrapetrous internal carotid aneurysm after a routine myringotomy. The aneurysm was treated by occlusion of the internal carotid artery by the detachable balloon technique. Unfortunately, both balloons migrated and ischemic sequelae resulted when one of the balloons became lodged in the bifurcation of the internal carotid artery. The balloon was successfully retrieved during an emergency microsurgical embolectomy, and the child's neurological deficit was reversed. The management of both the intrapetrous aneurysm and the balloon migration are discussed.

Aneurysm↗