PubMed Health⌕ Search

Biomedical subjects

C J Chung

Publications and source records attributed to C J Chung.

At least 19 recordsLinked to original sources
PubMed2001

Canines as sentinel species for assessing chronic exposures to air pollutants: part 1. Respiratory pathology.

A complex mixture of air pollutants is present in the ambient air in urban areas. People, animals, and vegetation are chronically and sequentially exposed to outdoor pollutants. The objective of this first of 2 studies is to evaluate by light and electron microscopy the lungs of Mexico City dogs and compare the results to those of 3 less polluted cities in MEXICO: One hundred fifty-two clinically healthy stray mongrel dogs (91 males/61 females), including 43 dogs from 3 less polluted cities, and 109 from southwest and northeast metropolitian Mexico City (SWMMC, NEMMC) were studied. Lungs of dogs living in Mexico City and Cuernavaca exhibited patchy chronic mononuclear cell infiltrates along with macrophages loaded with particulate matter (PM) surrounding the bronchiolar walls and extending into adjacent vascular structures; bronchiolar epithelial and smooth muscle hyperplasia, peribronchiolar fibrosis, microthrombi, and capillary and venule polymorphonuclear leukocytes (PMN) margination. Ultrafine PM was seen in alveolar type I and II cells, endothelial cells, interstitial macrophages (Mtheta), and intravascular Mtheta-like cells. Bronchoalveolar lavage showed significant numbers of alveolar macrophages undergoing proliferation. Exposure to complex mixtures of pollutants-predominantly particulate matter and ozone-is causing lung structural changes induced by the sustained inflammatory process and resulting in airway and vascular remodeling and altered repair. Cytokines released from both, circulating inflammatory and resident lung cells in response to endothelial and epithelial injury may be playing a role in the pathology described here. Deep concern exists for the potential of an increasing rise in lung diseases in child populations exposed to Mexico City's environment.

Age Distribution↗
PubMed2001

Hyperbaric spinal ropivacaine for cesarean delivery: a comparison to hyperbaric bupivacaine.

UNLABELLED: We evaluated the clinical efficacy and safety of spinal anesthesia with 0.5% hyperbaric ropivacaine compared with 0.5% hyperbaric bupivacaine for elective cesarean delivery. Sixty healthy, full-term parturients were randomly assigned to receive either 12 mg of 0.5% hyperbaric bupivacaine or 18 mg of 0.5% hyperbaric ropivacaine intrathecally. There were no significant differences in demographic or surgical variables or neonatal outcomes between groups. Onset time of sensory block to T10 or to peak level was later in the Ropivacaine group (P < 0.05). The median (range) peak level of analgesia was T3 (T1-5) in the Bupivacaine group and T3 (T1-4) in the Ropivacaine group. Time for sensory block to recede to T10 did not differ between groups. Duration of sensory block was shorter in the Ropivacaine group (188.5 +/- 28.2 min vs 162.5 +/- 20.2 min; P < 0.05). Complete motor block of the lower extremities was obtained in all patients. Ropivacaine also produced a shorter duration of motor blockade than bupivacaine (113.7 +/- 18.6 min vs 158.7 +/- 31.2 min; P < 0.000). The intraoperative quality of anesthesia was excellent and similar in both groups. Side effects did not differ between groups. Eighteen milligrams of 0.5% hyperbaric ropivacaine provided effective spinal anesthesia with shorter duration of sensory and motor block, compared with 12 mg of 0.5% hyperbaric bupivacaine when administered for cesarean delivery IMPLICATIONS: Eighteen milligrams of 0.5% hyperbaric ropivacaine provided effective spinal anesthesia with shorter duration of sensory and motor block, compared with 12mg of 0.5% hyperbaric bupivacaine when administered for cesarean delivery.

Adult↗
PubMed2001

Using CT of the cervical spine for early evaluation of pediatric patients with head trauma.

OBJECTIVE: The purpose of this study was to assess the effectiveness of CT of the cervical spine in addition to radiography in pediatric patients with suspected head trauma at the time of the CT head examination. MATERIALS AND METHODS: We identified 63 pediatric patients admitted to the emergency department who had head trauma and who underwent both head CT and neck radiography. Those who underwent CT of the cervical spine at the time of the head CT examination during their initial evaluation were compared for demographics, clinical status, mechanism of injury, and number of excess radiographs (number required by protocol minus number of films obtained) required to evaluate the cervical spine with those patients who did not undergo early CT of the cervical spine. RESULTS: Twenty-one patients (33%) underwent cervical spine CT at the time of the head CT examination. The number of excess radiographs differed significantly between these patients (2.1 +/- 2.6 vs 3.6 +/- 2.7, p = 0.04) and the comparison group. Patients who did not undergo early CT for whom excess radiographs were obtained had the following characteristics: they were older than 8 years (p = 0.03), were unrestrained in a motor vehicle crash (p = 0.04), had a Glasgow coma score of 13-15 (p = 0.01), and were intubated (p = 0.02). CONCLUSION: The number of repeated radiographs required to ascertain that the cervical spine is free of injury after suspected head trauma is significantly fewer when initial CT of the neck is performed at the time of head CT examination. Including cervical spine CT in trauma protocols for subgroups of children with head injuries may lead to more effective clearance of the pediatric cervical spine.

Cervical Vertebrae↗
PubMed2000

Exposure to air pollution is associated with lung hyperinflation in healthy children and adolescents in Southwest Mexico City: a pilot study.

Air pollution produces adverse health effects. The consequences of lifelong daily exposures to atmospheric pollutants upon the respiratory apparatus of healthy children are of considerable clinical importance. We investigated the association between exposure to a highly polluted urban environment with a complex mixture of air pollutants-ozone and particulate matter the predominant ones-and chest x-ray abnormalities in 59 healthy Mexican children who are lifelong residents of Southwest Metropolitan Mexico City (SWMMC), with a negative history of tobacco exposure and respiratory illnesses. Their clinical results and x-ray findings were compared to those of 19 Mexican control children, residents of a low-pollution area, with a similar negative history of tobacco exposure and respiratory illnesses. Ozone concentrations in SWMMC exceeded the U.S. Environmental Protection Agency (U.S. EPA) National Ambient Air Quality Standard (NAAQS) for O(3): 0.08 ppm as 1-h maximal concentration, not to be exceeded more than 4 times a year, on 71% of days in 1986 and 95% in 1997, with values as high as 0.48 ppm. Ozone maximal peaks are usually recorded between 2 and 5 pm coinciding with children's outdoor physical activities. Children in the control group reported no upper or lower respiratory symptomatology. Every SWMMC child complained of upper and/or lower respiratory symptoms, including epistaxis, nasal dryness and crusting, cough, shortness of breath, and chest discomfort. Children aged 7-13 yr had the most symptomatology, while 5- to 6-year olds and adolescents with the lowest number of statistically significant outdoor exposure hours had less respiratory symptoms. Bilateral symmetric mild lung hyperinflation was significantly associated with exposure to the SWMMC atmosphere (p = .0004). Chronic and sustained inhalation of a complex mixture of air pollutants, including ozone and particulate matter (PM), is associated with lung hyperinflation, suggestive of small airway disease, in a population of clinically healthy children and adolescents. Small airways are a target of air pollutants in SWMMC children, with ozone and PM being most likely responsible, based on experimental animal, controlled-chamber, and epidemiological data available. Our main concern is the potential likelihood for the development of chronic lung disease in this highly exposed population.

Adolescent↗
PubMed2000

Imaging of congenital anomalies of the branchial apparatus.

One of the most challenging topics for radiologists is congenital anomalies arising from abnormal embryogenesis of the branchial apparatus. Defects of the branchial apparatus result in a spectrum of anomalies that includes fistulas, sinuses, cysts, temporal bone anomalies, craniofacial malformations, and systemic disorders. A better understanding of the various radiologic abnormalities is aided by an understanding of their embryonic origins. This article reviews the spectrum of abnormalities that are secondary to anomalous embryogenesis of the branchial arches.

Branchial Region↗
PubMed2000

Imaging of congenital vascular and lymphatic anomalies of the head and neck.

Congenital lymphatic and vascular malformations and infantile hemangiomas can be combined under the heading of endothelial malformations. Based on their biologic behavior, endothelial malformations can be divided into two groups: infantile hemangiomas and vascular malformations. Vascular malformations can be subdivided into lymphatic, capillary, venous, and arteriovenous malformations. Often frightening for the patient and the patient's family, some endothelial malformations, however, will resolve; yet others can lead to long-term disfigurement and even can be fatal-due to airway obstruction, secondary infection, or exsanguination. When recognized early, however, the appropriate therapy, or watchful waiting, can be initiated, and the long-term physical and psychological consequences of these malformations can be minimized.

Arteriovenous Malformations↗
PubMed2000

The pediatric airway: a review of differential diagnosis by anatomy and pathology.

In children, lesions involving and affecting the airway are numerous and vary in origin. Categorizing these lesions by origin (traumatic, inflammatory, congenital or developmental, neoplastic, and vascular) or by anatomy (nasal airway and nasopharynx, oral airway and oropharynx, larynx, trachea, and extrinsic lesions) will aid in narrowing the differential diagnosis and may guide imaging.

Child↗
PubMed1999

Cervical neurofibromas in children with NF-1.

BACKGROUND: Children with neurofibromatosis type 1 (NF1) are at increased risk of developing plexiform neurofibroma throughout the body, including the cervical soft tissues. However, the incidence of cervical soft tissue tumors and the value of screening MR for children with NF1 are not known. PURPOSE: The purposes of this study were to determine the incidence and clinical significance of cervical tumors seen on MR imaging in children with NF1. MATERIALS AND METHODS: A retrospective review of the brain and orbit MR with cervical images obtained on 95 children who meet the NIH consensus criteria for NF1 and who are followed at our neurofibromatosis clinic was carried out. RESULTS: Cervical tumors were found on MR imaging in 21 of 95 (22%) children. Of 21 children with cervical tumors, 14 children were determined to be surgical candidates. In nine children, MR imaging altered the clinical management by demonstrating tumors for which surgery was indicated, but the tumors were not suspected prior to MR imaging. CONCLUSION: Cervical tumors are commonly seen in children with NF1. MR imaging may demonstrate a significant number of tumors that require surgery, but were not suspected prior to MR imaging.

Adolescent↗
PubMed1999

Magnetic resonance imaging of neuroblastoma using current techniques.

We evaluated the ability of current magnetic resonance (MR) scanning techniques to detect and stage neuroblastoma in children, using surgical and histopathologic correlation. We prospectively and retrospectively reviewed 16 MR examinations from 14 patients with neuroblastoma (13 patients) or ganglioneuroblastoma (1 patient) and compared these to computed tomography (CT) (5 patients) and pathology (all patients). Sequences included: precontrast T1-weighted and T2-weighted images, and gadolinium-enhanced T1-weighted images. The study time for each MR exam was also calculated. Five primary tumors were intrathoracic paraspinous masses, eight were adrenal, and 1 was presacral. Neural foraminal invasion was demonstrated on MR in four of 14 patients. Three of the four patients had undergone CT and neural foraminal invasion was shown in one. Vascular encasement was demonstrated in five of 14 patients on MR images. Three of the five patients had undergone CT and vascular involvement was shown in two. All cases of neural foramina invasion and vascular encasement were proven at surgery. There were no false positive or false negative MR studies of neural foraminal invasion or vascular encasement. Bone marrow invasion was shown in two of 14 patients on MR images which were confirmed by bone marrow aspirate. No false negative cases of bone marrow invasion was shown. In one patient, CT considered one neuroblastoma to be adrenal in location which was correctly shown to be intrathoracic on MR. The mean study time for MR imaging was 49 min. Current MR techniques are accurate at detecting and staging neuroblastoma, and coverage of chest, abdomen, and pelvis can be performed in less than one hour.

Adrenal Gland Neoplasms↗
PubMed1999

Mutant cells selected during persistent reovirus infection do not express mature cathepsin L and do not support reovirus disassembly.

Persistent reovirus infections of murine L929 cells select cellular mutations that inhibit viral disassembly within the endocytic pathway. Mutant cells support reovirus growth when infection is initiated with infectious subvirion particles (ISVPs), which are intermediates in reovirus disassembly formed following proteolysis of viral outer-capsid proteins. However, mutant cells do not support growth of virions, indicating that these cells have a defect in virion-to-ISVP processing. To better understand mechanisms by which viruses use the endocytic pathway to enter cells, we defined steps in reovirus replication blocked in mutant cells selected during persistent infection. Subcellular localization of reovirus after adsorption to parental and mutant cells was assessed using confocal microscopy and virions conjugated to a fluorescent probe. Parental and mutant cells did not differ in the capacity to internalize virions or distribute them to perinuclear compartments. Using pH-sensitive probes, the intravesicular pH was determined and found to be equivalent in parental and mutant cells. In both cell types, virions localized to acidified intracellular organelles. The capacity of parental and mutant cells to support proteolysis of reovirus virions was assessed by monitoring the appearance of disassembly intermediates following adsorption of radiolabeled viral particles. Within 2 h after adsorption to parental cells, proteolysis of viral outer-capsid proteins was observed, consistent with formation of ISVPs. However, in mutant cells, no proteolysis of viral proteins was detected up to 8 h postadsorption. Since treatment of cells with E64, an inhibitor of cysteine-containing proteases, blocks reovirus disassembly, we used immunoblot analysis to assess the expression of cathepsin L, a lysosomal cysteine protease. In contrast to parental cells, mutant cells did not express the mature, proteolytically active form of the enzyme. The defect in cathepsin L maturation was not associated with mutations in procathepsin L mRNA, was not complemented by procathepsin L overexpression, and did not affect the maturation of cathepsin B, another lysosomal cysteine protease. These findings indicate that persistent reovirus infections select cellular mutations that affect the maturation of cathepsin L and suggest that alterations in the expression of lysosomal proteases can modulate viral cytopathicity.

Animals↗
PubMed1999

Children with congenital pulmonary lymphangiectasia: after infancy.

OBJECTIVE: The objective of this original report is to describe the characteristic chest imaging findings in children with primary congenital pulmonary lymphangiectasia who survive infancy. CONCLUSION: In children with primary congenital pulmonary lymphangiectasia, increased interstitial markings decrease over time and increased hyperinflation is associated with persistent patchy areas of ground-glass opacity.

Child↗
PubMed1998

Malignant intraperitoneal neoplasms of childhood.

OBJECTIVE: The purpose of this paper is to review and categorize the CT appearances of primary and secondary intraperitoneal neoplasms in children. MATERIALS AND METHODS: We retrospectively reviewed the CT images of 14 cases of intraperitoneal neoplasms. They were reviewed for bowel wall thickening, mesenteric nodules, ascites, calcification, peritoneal nodules, omental caking, and contrast enhancement. RESULTS: Computed tomography images of 14 cases of intraperitoneal neoplasms were evaluated: rhabdomyosarcoma (5), lymphoma (3), neuroblastoma (2), germ cell tumor (1), mesothelioma (1), Wilms tumor (1), and hepatocellular carcinoma (1). Nodular enhancement was seen in all cases, ascites in most, significant bowel wall thickening only with lymphoma, and calcification only with germ cell tumors. Omental caking was present both with rhabdomyosarcoma and lymphoma. CONCLUSIONS: While rare in pediatrics, intraperitoneal neoplasms occur in children, and CT is useful in identifying these peritoneal neoplasms.

Child↗
PubMed1998

The efficacy of intrathecal neostigmine, intrathecal morphine, and their combination for post-cesarean section analgesia.

UNLABELLED: We designed this study to evaluate the postoperative analgesic efficacy and safety of intrathecal (i.t.) neostigmine, i.t. morphine, and their combination in patients undergoing cesarean section under spinal anesthesia. Seventy-nine term parturients were randomly divided into four groups to receive isotonic sodium chloride solution 0.2 mL, neostigmine 25 microg, morphine 100 microg, or the combination of i.t. neostigmine 12.5 microg and morphine 50 microg with i.t. 0.5% hyperbaric bupivacaine 12 mg. There were no significant differences among the four groups with regard to spinal anesthesia, maternal blood pressure and heart rate, or fetal status. Postoperative analgesia was provided by i.v. patient-controlled analgesia (PCA) using fentanyl and ketorolac. Compared with the saline group, the time to first PCA use was significantly longer in the neostigmine group (P < 0.001), with lower 24-h analgesic consumption (P < 0.001). Nausea and vomiting were the most common side effects of i.t. neostigmine (73.7%). Analgesic effectiveness was similar between the neostigmine and morphine groups. Compared with the neostigmine group, the combination group had significantly prolonged analgesic effect and reduced 24-h PCA consumption (P < 0.05) with less severity of nausea and vomiting (P = 0.058). Compared with the morphine group, the combination group tended to have prolonged times to first PCA use (P = 0.054) with a lower incidence of pruritus (P < 0.03). IMPLICATIONS: Intrathecal (i.t.) neostigmine 25 microg produced postoperative analgesia for cesarean section similar to that of i.t. morphine 100 microg, but with a high incidence of nausea and vomiting. The combination of i.t. neostigmine 12.5 microg and i.t. morphine 50 microg may produce better postoperative analgesia with fewer side effects than i.t. neostigmine 25 microg or i.t. morphine 100 microg alone.

Adult↗
PubMed1998

Intraperitoneal rhabdomyosarcoma in children: incidence and imaging characteristics on CT.

OBJECTIVE: The purpose of this study was to determine the incidence and CT imaging features of intraperitoneal rhabdomyosarcoma in children. CONCLUSION: Approximately 10% of children with rhabdomyosarcoma may have intraperitoneal neoplastic involvement either at the time of diagnosis or subsequently. On CT, intraperitoneal rhabdomyosarcomas are associated with ascites, enhancing nodules, masses, a pseudomyxoma peritonei-like appearance, and omental caking.

Adolescent↗
PubMed1998

Ehrlichiosis: findings on chest radiographs in three pediatric patients.

OBJECTIVES: Ehrlichiosis is a newly recognized tick-borne infection affecting both children and adults. The disease is usually mild, with flulike symptoms, but can be fatal. We present the chest radiographs and, in one case, the chest CT scan of all recognized pediatric cases of ehrlichiosis to date from our institution. CONCLUSION: Ehrlichiosis should be included in the differential diagnosis of acutely ill pediatric patients with a history of possible tick exposure and radiographic patterns of interstitial prominence, alveolar opacities, or consolidation that may be associated with pleural effusion.

Adolescent↗
PubMed1998

Spinal intradural cerebellar ectopia.

An ectopic cerebellum, as in Chiari malformations and ectopic cerebellar dysplastic tissue, is a common finding; however, the presence of an organized ectopic cerebellum is exceedingly rare. We describe the MR imaging, surgical, and histologic appearance of an intraspinal ectopic cerebellum in an infant.

Cerebellum↗