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Biomedical subjects

S Chuang

Publications and source records attributed to S Chuang.

At least 19 recordsLinked to original sources
PubMed1994

Localized scleroderma: imaging features.

Localized scleroderma is distinct from the diffuse form of scleroderma and does not show Raynaud's phenomenon and visceral involvement. The imaging features in 23 patients ranging from 2 to 17 years of age (mean 11.1 years) were reviewed. Leg length discrepancy and muscle atrophy were the most common findings (five patients), with two patients also showing modelling deformity of the fibula. One patient with lower extremity involvement showed abnormal bone marrow signals on MR. Disabling joint contracture requiring orthopedic intervention was noted in one patient. In two patients with "en coup de sabre" facial deformity, CT and MR scans revealed intracranial calcifications and white matter abnormality in the ipsilateral frontal lobes, with one also showing migrational abnormality. In a third patient, CT revealed white matter abnormality in the ipsilateral parietal lobe. In one patient with progressive facial hemiatrophy, CT and MR scans showed the underlying hypoplastic left maxillary antrum and cheek. Imaging studies of areas of clinical concern revealed positive findings in half our patients.

Adolescent↗
PubMed1991

Brain tumors in children and adolescents--II. The neuroanatomy of deficits in working, associative and serial-order memory.

The neuroanatomy of memory deficits was studied in 46 children and adolescents with brain tumors. CT-scan reconstructions of 88 brain regions were coded with respect to tumor and related damage, and multiple regression procedures established patterns of brain damage predictive of memory deficits. Two forms of memory revealed non-overlapping focal neuroanatomical substrates: memory for the serial order of pictures that corresponded to heard words involved structures in the limbic system and hypothalamic-pituitary axis; whereas working memory, in which each of a succession of heard words is stored in temporary memory long enough to be compared to or contrasted with incoming words, involved the pineal-habenular region and the anterior and medial thalamic nuclei. Memory for semantically-based word-picture associations, in contrast, was unaffected by tumors in several subcortical brain regions. These data bear on current analyses of the neural substrates of associative and representational memory.

Adolescent↗
PubMed1987

The surgical treatment of childhood moyamoya disease.

Moyamoya disease is a progressive disorder, predominantly seen in childhood, that can cause severe permanent disability. The search for effective treatment has largely been unsuccessful in the past, but recent efforts at surgical intervention have shown promising results. The natural history of moyamoya disease, the options for treatment, and a series of patients from the Hospital for Sick Children in Toronto are reviewed. The results of surgical treatment are encouraging and the authors believe that it should be offered to all pediatric patients in the progressive stage of the disease.

Adolescent↗
PubMed1986

Tumors and cysts.

"Congenital" tumors that cause hydrocephalus early in life are large masses and can easily be detected by ultrasound. CT is better for differentiating among the diverse types of mass lesions and is performed after screening by ultrasound. In our experience, ultrasound has proved successful for visualizing all of the intracranial cysts except those in the temporal fossa. Most patients with temporal fossa cysts, however, have other symptoms and signs, such as asymmetric head and seizures that lead to further investigation and correct diagnosis despite the failure to identify the temporal cysts by ultrasound. With newer and better ultrasound equipment, the detection of temporal fossa arachnoid cysts will be improved. We believe that neurosonography should be the initial tool for investigating infants and neonates who present with large heads or abnormally rapid increase in head size.

Brain↗
PubMed1986

Lumbo-peritoneal shunt malfunction. A new, simple and reliable CT sign.

Sixty CT scans in 31 patients who underwent lumboperitoneal shunting for communicating hydrocephalus showed that the size of the ventricles did not represent a good indicator of shunt malfunction. Instead, we discovered that the size of the basal cisterns around the brain stem enabled us to predict blockage earlier and more reliably. In a well functioning shunt, the basal cisterns are usually not visualized. In children with clinical shunt malfunction the cisterns dilate and become visible again. This occurs earlier and more frequently than ventricular enlargement. We therefore conclude that visible cisterns in association with persistent symptoms of malfunction are more reliable predictors of a true blockage that requires shunt revision than serial studies of ventricular size.

Brain↗
PubMed1986

Pediatric surgical neuroangiography. A multicentre approach.

Adult patients who require sophisticated embolization procedures are usually referred to centres where such expertise is available. Because of the special circumstances in the pediatric age group, this type of referral is often not feasible. The authors describe a model in which multiple pediatric institutions have access to sophisticated interventional neuroradiologic procedures through the collaboration of a group of neuroradiologists. The preliminary results are encouraging and appear to indicate that embolization in the pediatric age group can be safe and reliable if performed by well trained teams.

Child↗
PubMed1984

Computed tomography in Alexander's disease.

Computed tomography demonstrated contrast-enhancing lesions in the periventricular frontal regions, caudate nuclei, and thalami in an infant with Alexander's disease. The distribution of the enhancing lesions corresponded to the areas in which Rosenthal fibers were most prominent. These radiological findings have not been described in other white matter diseases; thus, they may help to distinguish Alexander's disease from Canavan's disease and decrease the necessity for diagnostic brain biopsy.

Brain↗
PubMed1983

Yeast inorganic pyrophosphatase substrate recognition.

Monodentate Co(NH3)5PPi was determined not to be a substrate for yeast inorganic pyrophosphatase while P1,P2-bidentate Co(NH3)4PPi was turned over by the enzyme at a rate of 7.5 min-1. A kinetic analysis of the substrate activities of the P1,P2-bidentate complexes, Co(en)2PPi, Cr(NH3)4PPi, Cr(H2O)(NH3)3PPi, and Cr(H2O)2(NH3)2PPi, and Cr(H2O)4PPi was carried out in order to access the potential role of the metal-water ligands in productive binding. While substitution of the H2O ligands with NH3 ligands had a minimal affect on the Km for Mg2+, the binding affinity of the complexes decreased with an increasing NH3/H2O ligand ratio as did the turnover number of the corresponding central complexes. The Co(en)2PPi complex was hydrolyzed at a rate approximately 0.6% of that for the Co(NH3)4PPi complex. The substrate activities of beta, gamma-bidentate Co(NH3)4PPPi and alpha, beta, gamma-tridentate Co(NH3)3PPP with pyrophosphatase were also tested. While both complexes were shown to bind tightly to the Mg2+-activated enzyme neither was hydrolyzed. On the other hand, in the presence of the Zn2+-activated enzyme the tridentate complex was turned over at a rate of 0.17 min-1 while the bidentate complex remained inert to hydrolysis.

Binding Sites↗
PubMed1983

Radiology of the suprapatellar region.

The gross and radiological anatomy of the suprapatellar region has been reviewed and its clinical application outlined. In most patients an accurate assessment of the presence of effusion and lipohaemarthrosis of the knee joint can be made and the possibility of excluding joint disease is discussed. In the individual patient the careful application of the radiological anatomy of this region may prevent mistakes in the localisation of various pathological processes.

Contrast Media↗
PubMed1982

Intracranial neoplasms in children: the effect of computed tomography on age distribution.

In a review of all children with brain neoplasms evaluated at a large pediatric center during a three-year period following the introduction of computed tomography (CT), a change was observed in the age distribution at the time of clinical presentation as compared with a previous series evaluated prior to the introduction of CT. In children under six years of age, there was a highly significant trend for earlier diagnosis; within this age group, relatively more children were diagnosed in the first two years of life. Between six and twelve years of age, there was no change in frequency of brain tumor diagnosis between the two series. Above age twelve, there was again noted a highly significant increase in detection of brain tumors in the more recent series. These differences between the two series may be attributed, at least in part, to earlier referral and diagnosis since the advent of CT, although other factors cannot be excluded as possible causes of the differences.

Adolescent↗
PubMed1981

The CT appearance of avulsion of the posterior vertebral apophysis. A case report.

Avulsion and posterior dislocation of the posterior dislocation of the posterior part of the vertebral apophysis is a rare condition, occurring mainly in adolescence. If the avulsed part is ossified it may be diagnosed with conventional X-rays including myelography. The present case shows that CT scan with sagittal reconstruction gives exact information of the nature of the lesion as well as its extension into the spinal canal, and that CT alone is sufficient for preoperative diagnosis.

Adolescent↗
PubMed1981

CT for trauma to the base of the skull and spine in children.

Five patients have been selected to demonstrate the diagnostic accuracy of CT in cases of traumatic damage to the base of the skull and spine in infants and children. Ct is superior to any other diagnostic radiological technique as bone and soft tissues are usually equally well demonstrated during one visit to the Radiology Department. Thus, CT is considered to be the primary investigative procedure of choice to evaluate trauma of the base of the skull and spine in infants and children.

Adolescent↗
PubMed1981

Case report. Computed tomography of the brain in severe hypoglycaemia.

Computed tomographic (CT) findings in a case of extreme hypoglycaemia induced by an overdose of chlorpropamide are described. Brain lesions tend to be preferentially localized along the boundary zones ("watersheds") between the territories of the main cerebral arteries. In our case, generalized brain damage occurred during severe hypoglycaemic coma. Neuropathological changes in this condition have been the subject of previous studies in experimental animals. Computed tomography allows follow-up studies of the human brain damaged by hypoglycaemic coma. Abnormalities revealed by CT probably represent reparative tissue reactions that indirectly reflect the extent of neuronal destruction.

Adolescent↗
PubMed1979

Normal cord in infants and children examined with computed tomographic metrizamide myelography.

Computed tomographic metrizamide myelography (CTMM) was performed on 25 infants and children and 2 adults with normal spinal cords. Both the cord and the cauda equina were precisely outlined. The most detailed information was obtained with a small window setting, with the image subsequently magnified and color-reversed. Hounsfield-unit measurements alone were inaccurate. Advantages of CTMM include: high accuracy in demonstrating the intrathecal contents of the spine; less need for general anesthesia; and the need for a smaller amount of water-soluble contrast material than in conventional myelography. In selected cases of intraspinal abnormality in children, CTMM is recommended.

Adolescent↗
PubMed1979

Computed tomographic metrizamide myelography in syringohydromyelia.

Four patients with surgically verified syringohydromyelia, including 2 with and 2 without a collapsing cord, were examined with computed tomographic metrizamide myelography (CTMM). When the cord is collapsed, or a contrast-containing cyst is observed on the scan, no further examination is necessary. If the cord is not collapsed, it is difficult to differentiate an intramedullary cyst from a tumor. Flattening of the ventral border of the cord in the supine position, coupled with an increased transverse diameter and alteration of the normally smooth, oval shape are suggestive of syringohydromyelia.

Adolescent↗