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Biomedical subjects

K H Choi

Publications and source records attributed to K H Choi.

At least 163 records · Page 9Linked to original sources
PubMed1988

Choroidal hematoma and effusion: evaluation with MR imaging.

To evaluate the usefulness of magnetic resonance (MR) imagining in the evaluation of choroidal pathologic conditions, the authors studied 15 patients with either choroidal hematoma or choroidal effusion with a 1.5-T MR imager. These two lesions were reliably distinguished from each other on the basis of MR findings. Choroidal hematomas appeared as lenticular-shaped masses in the wall of the eyeball, and signal intensity depended on the age of the hematoma. Choroidal effusions appeared as crescentic or ring-shaped areas of increased signal on both T1- and T2-weighted images in an anatomic distribution corresponding to the choroidal and suprachoroidal spaces.

Adult↗
PubMed1984

Cartilage involvement in laryngeal carcinoma: correlation of CT and pathologic macrosection studies.

Fifteen patients with laryngeal epidermoid carcinoma underwent CT of the larynx prior to surgery. Whole mount sections of the extirpated larynx cut in the horizontal plane were compared with the corresponding level of the preoperative CT sections. This study in particular was designed to evaluate the accuracy of diagnosing cartilage involvement by CT and to correlate CT findings with histologic involvement. Our results indicate that CT correlates well with anatomic location of gross cartilage involvement by the tumor; however, small macroscopic invasion of the laryngeal cartilages may be difficult to diagnose with CT. Microscopic involvement of the cartilages cannot be diagnosed with CT. Decisions regarding conservation surgery cannot be based on CT evaluation alone.

Aged↗
PubMed1984

Cystic mural nodule in cerebellar hemangioblastoma: CT demonstration.

An example of a form of cystic hemangioblastoma of the cerebellum in which the mural nodule itself showed a central cystic area is presented. Although the precise etiology of the cystic component within hemangioblastoma tumor nodules is not known, it probably results from tumor degeneration. Computed tomography is valuable in identifying this feature, which, if present, is very suggestive of the diagnosis of hemangioblastoma. Other diagnostically useful CT features of hemangioblastoma that were present in this case included location of the mural nodule adjacent to the nearest pial surface, isodensity of the nodule on the preinfusion scan, and very rapid circulation of contrast material through the wall of the nodule, demonstrated by dynamic CT technique.

Adult↗
PubMed1983

Tumor formation by SV40-transformed human cells in nude mice: the role of SV40 T antigens.

Human cells transformed in vitro by SV40 rarely form tumors in nude mice. We examined whether these cells as a group are inherently nontumorigenic or whether they are potentially tumorigenic but rejected by the athymic host, possibly by nonspecific immune mechanisms. SV80 and NG8 are SV40-transformed human cell lines that express all of the transformed properties, including anchorage-independent growth, but do not form tumors in adult nude mice after injection of as many as 10(8) cells. Both the SV80 and NG8 cell lines have SV40-specific transplantation antigens which crossreact with those present on SV40-transformed (but tumorigenic) rodent cells. We found that SV80 cells, though not NG8 cells, induced progressively growing lethal tumors if the cells are injected repeatedly into neonatal nude mice. Somatic cell hybrids between SV80 or NG8 cells and a highly tumorigenic cell line derived from a human tumor continue to express the virus-induced antigens and fail to form tumors in adult nude mice. These results strongly suggest that at least for some SV40-transformed human cells, the failure to form tumors in nude mice may be due to their expression of virus-induced transplantation antigens rather than the absence of tumorigenic potential.

Animals↗
PubMed1981

Inhibition of excision-repair of ultraviolet damage in human cells by exposure to methyl methanesulfonate.

Unscheduled DNA synthesis and excision of pyrimidine dimers in human cells exposed to ultraviolet let were inhibited by exposure to methyl methanesulfonate (MMS, 1-2 mM), but repair of MMS damage was not inhibited by UV light. Because the pathways for excision of pyrimidine dimers and alkylation damage have previously been shown to be different, this observation implies a direct effect of alkylation on repair enzymes. We estimate that if inhibition is due to protein alkylation, the UV repair system must present an extremely large target to alkylation and may involve a complex of protein subunits in the order of 1 million daltons such that 1 or more alkylations occur per complex at the concentrations used. These results also indicate that the method of exposing cells to 2 DNA-damaging agents to determine whether they are repaired by common or different pathways can be quite unreliable because of other effects on the repair systems themselves.

Animals↗
PubMed1980

Morphological changes during conversion of Clostridium saccharoperbutylacetonicum to protoplasts by sucrose-induced autolysis.

When exponentially growing cells of Clostridium saccharoperbutylacetonicum (ATCC 13564) were exposed to hypertonic concentrations of sucrose (0.3--0.5 M), rapid degradation of the cell wall occurred (sucrose-induced autolysis). The morphological changes from the original rod-shaped cells to protoplasts during the sucrose-induced autolysis were investigated by phase contrast and electron microscopy. When the cells were autolysed in the sucrose solution (0.35 M), each cell began to swell at the middle or at one pole and then formed a small bulb at the swollen part. The bulk consisted of the cytoplasm which was enveloped by the plasma membrane and extruded from the small gap produced by the degradation of the cell wall. The bulb gradually enlarged as lysis progressed, and finally became a protoplast which had no cell wall. The large pre-division cell frequently formed the bulb at the middle (septal site), while the small post-division cell formed the bulb at the pole.

Autolysis↗
PubMedDate not supplied

Differential permeability of lymphatic and blood vessels in determining the route of metastasis as demonstrated by indirect lymphography.

Indirect mammo-lymphography with serial radiograms was made on rats bearing three established rat mammary carcinomas (SMT-2A, TMT-50, MT-W9B), with the water-soluble contrast medium, Iotasul. In the lymphogenously metastasizing SMT-2A, fine lymphatic sprouts from the tumor were seen converging into an afferent lymph vessel that was extending toward a metastatic regional lymph node, in 15-30 min. For 45 min, the dye remained localized in the primary tumor with no other vascular structures or viscera visible until it emerged in the urinary bladder, indicating that Iotasul was absorbed slowly into the systemic circulation via lymphatics and diluted beyond recognition by lymph and blood, and then reconcentrated in urine. In contrast, in the hematogenously metastasizing TMT-50, Iotasul was rapidly diffused into the blood stream, revealing the inferior caval vein within 5 min, and by 15 min the heart, aorta, common carotid arteries, kidney and ureter were all clearly revealed. In the non-metastasizing MT-W9B host, several small vascular markings around the tumor were seen by 10 min and the outline of kidneys and urinary bladder in 15 min, suggesting that the dye was also absorbed through blood capillaries but somewhat slowly. Thus, the differential vascular permeability in rat mammary tumors revealed by Iotasul has not only helped to distinguish lymphatics from blood vessels, but also to correlate it with their metastatic potential.

Adenocarcinoma↗
PubMedDate not supplied

Gene polymorphisms of endothelial nitric oxide synthase and angiotensin-converting enzyme in patients with lung cancer.

The objectives of this study were to examine the possible involvement of endothelial nitric oxide synthase (ecNOS) and angiotensin-converting enzyme (ACE) genes in the genetic basis of lung cancer. Two hundred eighteen patients with lung cancer and 121 healthy subjects were included in this study. The ecNOS and ACE genotypes were determined in all subjects by polymerase chain reaction. The distribution of genotypes of ecNOS gene was significantly different in the lung cancer group than in the control population. ACE genotype distribution was not significantly different in the lung cancer group compared with the control group. These results suggest that polymorphisms of the ecNOS gene, but not the ACE gene, may be associated with the development of lung cancer.

Chi-Square Distribution↗
PubMedDate not supplied

Treatment of infections due to multiresistant Neisseria gonorrhoeae with sulbactam/ampicillin.

Between January and April 1984, 229 of 448 male patients with urethritis at the Choong-Ku Venereal Disease Clinic in Seoul had positive urethral cultures: 66 for penicillinase-producing Neisseria gonorrhoeae (PPNG) and 163 for non-penicillinase-producing N. gonorrhoeae (non-PPNG). Forty-five men with PPNG urethritis were enrolled in a study of the efficacy of treatment with sulbactam/ampicillin plus probenecid. Diagnosis and evaluation of cure were based on culture results. The agar-plate dilution method was used for susceptibility testing, and the chromogenic cephalosporin test was used for detection of beta-lactamases. MICs of various antibiotics for the isolates were high. MICs of sulbactam/ampicillin were 0.25-4 micrograms/ml, with an MIC90 of 4 micrograms/ml, a value 16-fold lower than that for ampicillin alone (MIC90 greater than 32 micrograms/ml). Patients were treated with 1 g of probenecid orally and either one vial of sodium sulbactam/ampicillin or two vials intramuscularly. Each vial contained 0.5 g of sodium sulbactam and 1 g of sodium ampicillin. Patients were followed up for three to five days. All patients but one were cured, and no remarkable adverse reactions were noted. The two regimens of sulbactam/ampicillin were equally effective in the treatment of uncomplicated PPNG in men.

Adult↗
PubMedDate not supplied

CT characteristics of orbital pseudotumors and other orbital inflammatory processes.

Orbital pseudotumor is a nonspecific inflammatory process of unknown etiology that may mimic a true orbital neoplasm, specifically lymphoma. It exhibits a highly variable clinical and radiographic presentation. Thirty-nine patients with a presumptive diagnosis of orbital inflammatory disease were examined with CT and evaluated with respect to 13 findings associated with inflammatory disease of the orbit. Pseudotumor was included as part of the differential diagnosis in 25 patients. Twenty-one cases received a final (clinical) diagnosis of pseudotumor. The remainder were comprised of a broad range of orbital inflammatory conditions. Key radiographic features required to entertain or exclude the diagnosis of pseudotumor included establishing the presence of an orbital mass, extraocular muscle enlargement, bony erosion, enhancement, and associated paranasal sinus disease.

Adult↗
PubMedDate not supplied

Eosinophilic cholangitis: US, CT, and cholangiography findings.

We report a case of eosinophilic cholangitis, with US, CT, and cholangiographic findings. The lesion showed marked wall thickening of cystic and common bile ducts on US and CT together with mild diffuse narrowing of the common duct on cholangiography.

Bile Ducts↗
PubMedDate not supplied

The plica syndrome: diagnostic value of MRI with arthroscopic correlation.

PURPOSE: Our goal was to evaluate the diagnostic value of MRI in plica syndrome. METHOD: MR images of a patient group (n = 55) with arthroscopically confirmed pathologic mediopatellar plicae were retrospectively analyzed and compared with those of a control group (n = 100). We obtained axial multiplanar gradient-recalled (MPGR), axial T1-weighted, and sagittal T2-weighted MR images. MR images were assessed for the width and length of all medial plicae. RESULTS: In the diagnosis of plica syndrome, sensitivity and specificity were 73 and 78% on axial MPGR images, 71 and 83% on sagittal T2-weighted images, and 95 and 72% on combination of both images, respectively. The incidence of pathologic medial plica increased with a criterion of extension beyond the medial end of the patella on axial MPGR images. CONCLUSION: MRI is a useful screening method in the diagnosis of plica syndrome.

Adolescent↗
PubMedDate not supplied

MRI of tuberculous pyomyositis.

PURPOSE: The purpose of this article is to describe the findings of MRI in tuberculous pyomyositis (PM). METHOD: The MR images of four proven cases of tuberculous PM were retrospectively reviewed and analyzed with clinical and laboratory findings. The location, signal intensity on T1- and T2-weighted spin echo images, presence of abscess, signal intensity of peripheral rim, patterns of contrast enhancement, and associated findings were evaluated. RESULTS: On MR images, all cases demonstrated low signal intensity on T1-weighted images and high signal intensity on T2-weighted images in a single muscle. Abscess was seen in all cases. Peripheral rim showed subtle hyperintensity on T1-weighted images and hypointensity on T2-weighted images. After gadolinium infusion, peripheral rim enhancement was observed in all cases. Cellulitis was associated in one case. The patients clinically presented with a palpable mass of long duration. CONCLUSION: Tuberculous PM shows characteristic findings of a well demarcated abscess with rim enhancement at MRI and can be distinguished from other soft tissue masses.

Abscess↗
PubMedDate not supplied

Chondroblastoma: MR characteristics with pathologic correlation.

PURPOSE: The purpose of this study was to describe the MR findings of chondroblastoma with pathologic correlation. METHOD: In 22 patients with pathologically proven chondroblastoma, MR signal characteristics were correlated with pathological findings. RESULTS: On T2-weighted images, 12 (55%) lesions were hyperintense with hypointense areas in 9 lesions, whereas 10 (45%) were hypointense. Therefore, 19 of 22 (86%) lesions with pathologic correlation had hypointense areas entirely (n = 10) or partly (n = 9) on T2-weighted images. On gadolinium-enhanced images, 13 (59%) lesions showed lobular enhancement and 9 (41%) showed marginal and septal enhancement. Low signal intensity on T2-weighted MR images was most strongly associated with an abundance of immature chondroid matrix, hypercellularity of the chondroblasts, calcifications, and hemosiderin on histology. CONCLUSION: Chondroblastoma was found to show hypointense portions on T2-weighted images. Signal intensity on T1- and T2-weighted MR images in chondroblastoma was dependent on the amounts of histopathological components.

Adolescent↗
PubMedDate not supplied

N-butyl-2-cyanoacrylate pulmonary embolism after endoscopic injection sclerotherapy for gastric variceal bleeding.

PURPOSE: The purpose of this work was to describe the radiologic and clinical manifestations of n-butyl-2-cyanoacrylate pulmonary embolism (PE) after endoscopic injection sclerotherapy (EIS) for gastric variceal bleeding. METHOD: From 1992 to 1999, the medical records of 140 patients who had undergone EIS using n-butyl-2-cyanoacrylate were reviewed for identification of respiratory symptoms and amount of injection, and their pre- and postprocedure chest radiographs were reviewed to identify PE. In patients with PE, pre- and postprocedure chest radiographs (6/6), chest CT scans (3/6), lung perfusion scans (3/6), and follow-up chest radiographs (6/6) were analyzed retrospectively. RESULTS: Radiographically evident PE was observed in 6 (4.3%) of 140 patients. In comparison with patients without emboli, these patients received a higher mean volume of injection (4.2 vs. 1.8 ml) (p = 0.0011). Four of the six patients with pulmonary emboli had respiratory symptoms. Chest radiographs and CT scans showed unusual tubular or nodular, radiopaque pulmonary emboli along the pulmonary vessels. Multiple peripheral, wedge-shaped, subsegmental perfusion defects were seen on perfusion lung scans. In five of six patients, the radiographic abnormalities showed complete or partial resolution. There were no fatalities directly associated with PE. CONCLUSION: Radiographically evident PEs are uncommonly observed following EIS and appear to be more common in patients receiving a higher volume of liquid acrylate. Affected patients were either mildly symptomatic or asymptomatic, and there were no direct fatalities of this complication.

Adolescent↗
PubMedDate not supplied

Unusual acute encephalitis involving the thalamus: imaging features.

OBJECTIVE: To describe the brain CT and MR imaging findings of unusual acute encephalitis involving the thalamus. MATERIALS AND METHODS: We retrospectively reviewed the medical records and CT and/or MR imaging findings of six patients with acute encephalitis involving the thalamus. CT (n=6) and MR imaging (n=6) were performed during the acute and/or convalescent stage of the illness. RESULTS: Brain CT showed brain swelling (n=2), low attenuation of both thalami (n=1) or normal findings (n=3). Initial MR imaging indicated that in all patients the thalamus was involved either bilaterally (n=5) or unilaterally (n=1). Lesions were also present in the midbrain (n=5), medial temporal lobe (n=4), pons (n=3), both hippocampi (n=3) the insular cortex (n=2), medulla (n=2), lateral temporal lobe cortex (n=1), both cingulate gyri (n=1), both basal ganglia (n=1), and the left hemispheric cortex (n=1). CONCLUSION: These CT or MR imaging findings of acute encephalitis of unknown etiology were similar to a combination of those of Japanese encephalitis and herpes simplex encephalitis. In order to document the specific causative agents which lead to the appearance of these imaging features, further investigation is required.

Acute Disease↗