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Biomedical subjects

K H Chang

Publications and source records attributed to K H Chang.

At least 109 records · Page 6Linked to original sources
PubMed1996

Cerebral sparganosis: clinical manifestations, treatment, and outcome.

Cerebral sparganosis is a rare parasitic disease caused by infestation by the plerocercoid larva of Spirometra mansoni. The authors retrospectively analyzed 17 cases of cerebral sparganosis treated at Seoul National University Hospital between 1986 and 1994. The patients' ages at diagnosis ranged from 6 to 57 years (median 32 years) and the male/female ratio was 13:4. Diagnosis was based on radiological findings, serological test results, operative findings, and histopathological examinations. Characteristic magnetic resonance (MR) findings consisted of widespread white matter degeneration and cortical atrophy, mixed-signal lesion (low in the central and high in the peripheral regions on T2-weighted images) with irregular dense enhancement of central foci and changes in the location and shape of the enhancing lesion in follow-up studies. Ten patients underwent surgical removal of the parasitic lesion, six received medical treatment alone (five with praziquantel and one with antiepileptic drugs), and one underwent insertion of a ventriculoperitoneal shunt and a course of praziquantel. Follow-up periods ranged from 13 to 111 months (mean 49 months). Seven patients who underwent complete removal of the lesion, live worm, or degenerative worm with surrounding granuloma showed a favorable course. Patients who received medical treatment alone or incomplete removal exhibited progression in their neurological deficits and their seizures could not be controlled. Medication with praziquantel seemed to have no killing effect on live worms. The authors conclude that MR imaging is the most valuable modality for the early detection of cerebral sparganosis and that complete surgical removal of granuloma together with worms, whether they are alive or degenerative, is the treatment of choice.

Adolescent↗
PubMed1996

Fibrosing inflammatory pseudotumors involving the skull base: MR and CT manifestations with histopathologic comparison.

PURPOSE: To describe the MR and CT features of fibrosing inflammatory pseudotumors of the skull base region, and to document the MR signal intensity of the lesions with histopathologic comparison. METHODS: We reviewed the MR and CT studies of five patients with pathologically proved fibrosing inflammatory pseudotumor involving the skull base. Unenhanced spin-echo T1- and T2-weighted and contrast-enhanced T1-weighted MR images were obtained at 0.5 T in three patients and at 1.5 T in two patients. MR findings were correlated with histopathologic findings in all five cases, and the enhancement pattern was compared with CT findings in three cases. RESULTS: In three cases, the cavernous sinus was involved unilaterally, with adjacent extracranial infiltrative masses. In one case, both orbits, the cavernous sinuses, and the tentorium were involved with diffuse infiltrative lesions. One patient had an infiltrative nasopharyngeal mass; and in all five patients, MR images showed localized involvement of the skull base, with bone marrow replaced by tumor. The soft-tissue lesions were hypointense on T2-weighted images in all five cases and showed homogeneous contrast enhancement. Histopathologic studies revealed scanty inflammatory cell infiltration with densely fibrotic background in all cases. The hypointensity of the lesions on T2-weighted images seemed to be related to the degree of fibrosis. CONCLUSION: Fibrosing inflammatory pseudotumor shows characteristic MR findings of infiltrative lesion with bone destruction and hypointensity on T2-weighted images. The lack of mobile protons due to the fibrotic background and/or high cellularity of the lesions may be the reason for their hypointensity and weaker enhancement on MR images.

Adult↗
PubMed1995

The C terminus of mitosin is essential for its nuclear localization, centromere/kinetochore targeting, and dimerization.

Mitosin is a novel 350-kDa nuclear phosphoprotein that dramatically relocates from the evenly nuclear distribution in S phase to the centromere/kinetochore and mitotic apparatus in M phase. The dynamic relocalization of mitosin is accompanied by the phosphorylation of itself, suggesting that mitosin plays a role in mitotic progression. The molecular basis of nuclear localization and targeting of mitosin to the centromere/kinetochore were characterized using a set of epitope-tagged deletion mutants. The data indicate that the extreme C terminus (amino acids 2,487-3,113) of mitosin has both an independent centromere/kinetochore targeting domain and an unusually spaced bipartite nuclear localization signal. Moreover, the same centromere/kinetochore targeting domain was shown to be essential for the ability of mitosin to bind to itself or other putative mitosin-associated proteins through use of the yeast two-hybrid system. These results suggest that the C terminus of the mitosin is essential for its role in influencing cell cycle progression.

Amino Acid Sequence↗
PubMed1995

A comparative study on contrast enhancement between 0.5- and 2.0-Tesla field strength in rabbit VX2 carcinomas.

RATIONALE AND OBJECTIVES: Theoretically, the degree of contrast enhancement in magnetic resonance (MR) is affected by magnetic field strength. The authors conducted this study to compare the degree of MR contrast enhancement between 0.5 Tesla (T) and 2.0 T in VX carcinomas of rabbits. METHODS: In 12 rabbits with VX2 tumors, both 0.5 T and 2.0 T MR imaging was performed within 1 day before and after intravenous injection of gadopentetate dimeglumine. Each rabbit received an initial standard dose (0.1 mmol/KG) followed by and additional standard dose (total, double dose) during the MR study at each field strength. The degree of contrast enhancement in the VX2 tumors was assessed quantitatively. RESULTS: With standard and double dose studies, overall mean tumor and muscle contrast-to-noise ratio was higher at 2.0 T than 0.5 T by 95% and 81%, respectively. The double dose study showed higher contrast-to-noise ratio than the standard dose study at both field strengths. CONCLUSIONS: Results indicate that the effect of contrast enhancement increases with field strength.

Animals↗
PubMed1995

Characterization of a novel 350-kilodalton nuclear phosphoprotein that is specifically involved in mitotic-phase progression.

A gene assigned to human chromosome 1q32-41 encodes a novel protein of 3,113 amino acids containing an internal tandem repeat of 177 amino acids. The protein, which we have named "mitosin," was identified by direct binding to purified retinoblastoma protein in vitro with a region distantly related to the retinoblastoma protein-binding site of E2F-1. Mitosin is expressed throughout S, G2, and M phases of the cell cycle but is absent in G1. Its localization is dramatically reorganized from a rather homogeneous nuclear distribution in S phase to paired dots at the kinetochore/centromere region, to the spindle apparatus, and then to the midbody during M-phase progression. This spatial reorganization coincides closely with the temporal phosphorylation patterns of mitosin. Overexpression of N-terminally truncated mutants blocks cell cycle progression mainly at G2/M. These results suggest that mitosin may play an important role in mitotic-phase progression.

Amino Acid Sequence↗
PubMed1995

Contrast-enhanced MR angiography for the diagnosis of intracranial vascular disease: optimal dose of gadopentetate dimeglumine.

OBJECTIVE: Although contrast-enhanced MR angiography has been shown useful in evaluating intracranial vascular lesions, particularly those with slow flow, the optimal dose of contrast material has not been found. Accordingly, we performed a study to determine the optimal dose of gadopentetate dimeglumine for contrast-enhanced MR angiography of intracranial vascular diseases. SUBJECTS AND METHODS: In this prospective study, 152 consecutive adult patients suspected of having intracranial vascular diseases had cerebral MR angiograms. Images were obtained with a three-dimensional time-of-flight sequence with magnetization transfer saturation on a 1.5-T unit. Imaging parameters (43/8 [TR/TE], 20 degrees flip angle, 64 1-mm-thick sections) were identical in each MR angiogram. One hundred twenty-two of 152 patients were randomly assigned to receive one of four doses (0, 5, 10, or 20 ml) of gadopentetate dimeglumine for MR angiography (36, 37, 38, and 11 patients, respectively). In patients who had normal major cerebral arteries on MR angiograms, degree and extent of visualization of the cerebral veins and small intracranial arteries were rated blindly on a three-point scale, and the results were compared among the four groups given different doses of contrast material. In another 30 patients who had unenhanced and enhanced MR angiograms, the presence or absence of artifactual narrowing of the internal carotid artery or major cerebral arteries (caused by signal loss due to slow or turbulent flow seen only on unenhanced images) and the visibility of arteriovenous malformation were determined. RESULTS: In nearly all patients, regardless of the dose of contrast material, the cerebral veins were well visualized on MR images. Degree and extent of visualization of the cerebral veins appeared to depend on the dose of contrast material. In the 20-ml injection group, venous overlap limited interpretation of the small and large arteries, whereas in the 5- and 10-ml groups, the signal intensity of the veins was much less intense, causing no difficulty in interpretation. However, no significant differences in visibility of the small arteries were apparent between the unenhanced and enhanced MR angiograms, even though the small vessels were better visualized in some patients who received either 5 or 10 ml of contrast material. In six of the 30 patients who had both unenhanced and enhanced MR angiograms, the unenhanced images showed artifactual narrowing of the internal carotid or middle cerebral arteries, which proved to be normal on contrast-enhanced MR angiograms. Venous sinuses or draining veins were better delineated on contrast-enhanced MR angiograms in all six patients with arteriovenous malformation. CONCLUSION: Five to 10 milliliters of gadopentetate dimeglumine appears to be an optimal dose range for contrast-enhanced cerebral MR angiography. Use of this dose can help in differentiating true stenosis of large arteries from artifactual narrowing and in depicting small arteriovenous malformation with slow flow.

Adolescent↗
PubMed1995

MR imaging of central nervous system tuberculosis.

TB involving the CNS and its coverings is a complex and potentially devastating disease. The increasing incidence of this disease in both immunologically normal as well as immunologically incompetent populations makes the subject of TB one of universal concern. Although its appearance on MR is not specific, it is important in the proper clinical setting to recognize the range of possible patterns that can be observed on images. The inclusion of TB in the differential diagnosis on the basis of the patient's region of origin, the socioeconomic background of the patient, and the presence of underlying predisposing disease may potentially promote timely initiation of appropriate therapy.

Brain↗
PubMed1995

Congenital fistula from ectopic accessory parotid gland: diagnosis with CT sialography and CT fistulography.

We report a case of congenital fistula from ectopic accessory parotid gland to the cheek demonstrated by CT sialography and CT fistulography. The right parotid gland was abnormally located lateral to masseter muscle. The fistula was arising from an ectopic accessory parotid gland with ectopic duct positioned anterior to masseter muscle. CT sialography and CT fistulography were very helpful in the diagnosis and surgical planning.

Cheek↗
PubMed1995

Cystic expansile masses of the maxilla: differential diagnosis with CT and MR.

PURPOSE: To describe the CT and MR findings of various entities causing cystic expansile masses in the maxilla and the significance of the cortical bony plate between the lesions and sinus cavities in the differential diagnosis. METHODS: CT findings of 28 patients with cystic expansile masses of the maxilla, including 20 cases of maxillary mucoceles (17 postoperative mucoceles, 2 mucoceles of a septated compartment of the maxillary sinuses, and 1 maxillary antral mucocele with inflammatory ostial obstruction), 3 cases of fissural cyst, 4 cases of odontogenic cyst, and 1 case of maxillary cystic ameloblastoma, were reviewed. Six cases (4 postoperative mucoceles and 2 odontogenic cysts) were also examined with MR. RESULTS: A thin bony plate between the lesion and antral cavity was demonstrated in every extraantral lesion (ameloblastoma, fissural cysts, and odontogenic cysts) and distinguishing these abnormalities from the antral lesions (mucoceles). All mucoceles showed findings of antral lesions except 2 cases of mucoceles at the septated compartments of the sinuses, in which thin bony septa were identified between the lesions and remaining sinus cavities. Postoperative mucoceles showed hyperostotic and retracted bony walls caused by previous surgery and localized erosion of bony walls with localized bulging of the cystic masses in every case. CONCLUSION: In the differential diagnosis of cystic masses of the maxilla, careful identification of the bony walls of the antrum and bony septa may allow one to locate the origin of a mass as antral or extraantral. This is important to an appropriate differential diagnosis.

Adult↗
PubMed1995

Intracranial tuberculoma: comparison of MR with pathologic findings.

PURPOSE: To compare the MR signal intensity patterns and enhancement pattern of intracranial tuberculomas with their histopathologic features. METHODS: MR images of six patients with surgically proved intracranial tuberculoma were reviewed retrospectively and were compared with histologic findings of the resected specimen. Detailed histologic examination was performed to look for the extent and characteristics of caseation necrosis, fibrosis, and inflammatory cellular infiltrates at each area of different signal intensities and at the enhancing areas on MR. Signal intensities for T1- and T2-weighted images were compared with normal gray matter. RESULTS: On T1-weighted images, the granulomas showed a slightly hyperintense rim surrounded by a complete or partial rim of slight hypointensity and central isointensity or mixed isointensity and hyperintensity in five patients and homogeneous isointensity in one patient. Histologically, the zone of central isointensity or mixed intensity corresponded to caseation necrosis plus adjacent cellular infiltrates. The hyperintense and hypointense rims corresponded to the layers of collagenous fiber and the layers of the inflammatory cellular infiltrates, respectively. On T2-weighted images, the entire portion of the granuloma showed slightly heterogeneous isointensity or hypointensity with small markedly hypointense foci in five patients, and a hyperintense center surrounded by a hypointense rim in one patient. Histologic layers were not discriminated on T2-weighted images. On postcontrast T1-weighted images, there were single or multiple conglomerate ring enhancements within a tuberculoma in all six patients, corresponding to the layers of both collagenous and inflammatory cells. CONCLUSION: Combination of the described signal intensity patterns and conglomerate ringlike enhancing appearance of the lesion is characteristic of tuberculoma, and may play an important role in differentiating intracranial tuberculomas from other ring-enhancing brain lesions.

Adult↗
PubMed1994

Pharmaceutical application of LC-MS. 1--Characterization of a famotidine degradate in a package screening study by LC-APCI MS.

The application of LC-MS to characterize low-level degradates in pharmaceutical dosage formulations is a new and challenging field. In a package screening study, a low-level degradate of famotidine (1, 3-[[[2-[[aminoiminomethyl]-amino]-4-thiazolyl]methyl] thio]-N-(aminosulphonyl)-propanimid-amide, an H2-receptor antagonist, molecular weight: 337) was detected by HPLC in film-coated tablets packaged in child-resistant (CR) foil pouches which were stressed at 40 degrees C/75% relative humidities (RH) for 4 months. LC-atmospheric pressure chemical ionization (APCI) mass spectrometry using positive ion mode yielded a molecular weight of 349 for the degradate, suggesting that it was formed by the addition of one carbon to the famotidine molecule. A detailed analysis of the positive product ion mass spectrum of the protonated degradate ion in a LC-MS-MS study indicated that the carbon was added to the side of N-(aminosulphonyl)-propanimid-amide of famotidine. The structure of the degradate was determined to be 2, which was confirmed by LC-APCI MS and HPLC study of the product formed from the reaction of famotidine with formaldehyde--a one-carbon reagent.

Chromatography, High Pressure Liquid↗
PubMed1994

Initial and follow-up brain MRI findings and correlation with the clinical course in Wilson's disease.

We performed pretreatment brain MRIs in 25 patients with neurologically symptomatic Wilson's disease (WD) and clinical and MRI follow-up in 16 of them. All 25 pretreatment MRIs revealed abnormalities, with abnormal high-signal intensity (HSI) in bilateral thalami being the most common (92%). HSI lesions in the brainstem (84%) and the basal ganglia (72%) were also common. Brain atrophy was present in 88% of the 25 patients. In the follow-up period of 5 to 24 months, during which the patients were treated with D-penicillamine, both HSI lesions and neurologic symptoms improved in 88% of the 16 patients, but the brain atrophy did not change.

Adolescent↗
PubMed1994

Traumatic pseudoaneurysm of the intracavernous ICA presenting with massive epistaxis: imaging diagnosis and endovascular treatment.

Traumatic pseudoaneurysm of the intracavernous internal carotid artery (ICA) is a very rare cause of epistaxis but is a life-threatening clinical situation when left untreated. The authors have experienced four cases of traumatic pseudoaneurysm involving the intracavernous ICA. Delayed massive epistaxes developed 1 to 8 months after trauma and initial transient epistaxis in all four patients. Three of the cases were successfully managed by the detachable balloon occlusion (DBO) of the ICA along with the aneurysm openings. In one case, a large pseudoaneurysm destroying a large area of the central skull base with peripheral blood clot was demonstrated on computed tomography, magnetic resonance imaging, and angiography; this patient died due to massive epistaxis before the trial of DBO. Imaging findings of pseudoaneurysms involving the intracavernous ICA in the four cases are described, and the role of endovascular treatment is discussed.

Accidental Falls↗
PubMed1994

Cerebral paragonimiasis in early active stage: CT and MR features.

OBJECTIVE: Diagnosis of cerebral paragonimiasis in its early active stage is important because curative chemotherapy is possible. Accordingly, this study was undertaken to evaluate the CT and MR features of early active cerebral paragonimiasis. MATERIALS AND METHODS: We retrospectively reviewed the CT scans (n = 29) and MR images (n = 7) of the brain in 20 patients between 7 and 59 years old who had cerebral paragonimiasis in the early active stage. The diagnosis was based on a positive antibody test by enzyme-linked immunosorbent assay (ELISA) for paragonimiasis in serum and CSF. The diagnosis was confirmed surgically in seven patients. RESULTS: The most common and characteristic imaging finding was a conglomerate of ringlike enhancing lesions (grape-cluster appearance) with surrounding edema in one cerebral hemisphere in 11 patients (55%). Other nonspecific findings included a solitary ringlike lesion (n = 4) or irregular enhancing lesions (n = 2), localized hemorrhage with (n = 3) or without (n = 2) enhancing lesions, and a poorly defined non-hemorrhagic, nonenhancing lesion (n = 1). CONCLUSION: CT and MR findings of clustered ring-enhancing lesions, seen in approximately half of the cases of early cerebral paragonimiasis, are suggestive of cerebral paragonimiasis.

Adolescent↗
PubMed1994

Germinomas of the basal ganglia and thalamus: MR findings and a comparison between MR and CT.

OBJECTIVE: The purpose of this study was to describe the MR imaging appearance of germinomas in the basal ganglia and thalamus and to compare the MR findings with CT findings. MATERIALS AND METHODS: Eleven MR studies of 10 patients with pathologically proved germinomas in the basal ganglia or thalamus were retrospectively reviewed. In nine of the 10, the MR findings were compared with CT findings. All patients were male, and all except one were in their second decade of life. All the tumors were located in paraventricular areas. RESULTS: Most of the tumors were 4-7 cm in diameter. MR images showed that the tumors were mostly cystic in five patients, mostly solid with cystic components in four, and solid without cystic components in one. The solid portion mostly was isointense relative to the cerebral cortex for all MR pulse sequences. The cystic portion was hyperintense relative to CSF on T1- and T2-weighted images. MR images showed intratumoral hemorrhage in seven patients. It appeared as an area of hyperintensity on T1- and T2-weighted images in five patients and as a fluid-fluid level with marked hypointensity on T2-weighted images in two. Hemorrhage was not visualized on CT scans in any patient. Flecked or amorphous calcifications visualized on CT scans in two patients were hardly detectable on MR images. Peritumoral edema was usually minimal. CT scans and MR images obtained after injection of contrast material both showed heterogeneous and dense enhancement in the solid portions of the tumors. CONCLUSION: MR images of germinoma in the basal ganglia and thalamus show a large paraventricular mass. Cystic areas, focal hemorrhages, and minimal surrounding edema are common. Unlike CT, MR imaging allows characterization of intratumoral hemorrhage.

Adolescent↗
PubMed1994

[Continuing hospice care of cancer--a three-year experience].

The hospice at Mackay Memorial Hospital was established in February 1990. A group of team workers including physicians, nurses, social workers and the clergy were involved in this holistic care program for terminal cancer patients. Four hundred and seventy-nine patients were eligible for the program up to February 1993. Regarding duration of stay, 62.5% of patients resided for 14 days. Those surviving under 90 days constituted 75.5% of patients. Fifty-one point eight percent of patients died in the hospice and 18.2% died at home soon after being discharged from the hospice. Pain is the most common symptom among the patients. Treatment strategies vary according to the three-step-ladder protocol designed by WHO. Total pain relief was achieved in 80% of patients. Opportune private talking and family conferences formed the basis of the "peer model". Through this model, treatment decisions including physical, psychosocial and spiritual issues were made. Before the peer model, only 36 (10.3%) patients agreed with the idea of hospice care, while 257 (73.6%) patients agreed after the model was established. Awareness of dying was evident in 412 (86%) patients. Two hundred and eighty (68%) patients became aware of the prospect of death through guessing, while the other 132 (32%) patients were informed by medical staff. Problems encountered by the team workers included 1) needs in education and training, 2) psychological pressure, 3) management of loss and grief, 4) needs in supportive system and 5) troubles caused by families' lying to patients. The team workers were satisfied with the quality of care in 38.4% of patients and fairly satisfied with 30.7% of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗