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Biomedical subjects

M H Han

Publications and source records attributed to M H Han.

At least 73 records · Page 4Linked to original sources
PubMed1997

Re-evaluation of optimal dose of contrast medium for vascular enhancement in CT of the head and neck.

Adequate contrast enhancement of major neck vessels is more important than that of a tumour itself in CT of most head and neck tumours because of differentiation from neck node metastases. Our purpose was to re-evaluate the dosage of contrast medium for adequate vascular enhancement in CT of the head and neck. In a blind prospective fashion, 60 patients with a variety of head and neck lesions were randomised into three equal groups receiving 0.75, 1.0, or 1.25 ml/kg of meglumine ioglycate, 300 mg/ml. Contrast medium was administered by injector at 2 ml/s. The scan time and interscan delay were each 1 s, and total scan time 50-180 s. The scan was started immediately after administration of two-thirds of the contrast medium. The degree of vascular enhancement was assessed visually and quantitatively. We visually scored the degree of vascular enhancement as excellent (4 points), good (3), fair (2) or poor (1). For quantitative study, after measuring the CT numbers of the common or internal carotid artery (CA), internal jugular vein (IJV) and adjacent muscle at three levels, were calculated mean vessel/muscle contrast ratios. The degree of enhancement of the CA and IJV tended to increase with dose of the contrast media, but no examination was rated as showing poor enhancement in any group. The mean visual assessment scores for 0.75, 1.0, and 1.25 ml/kg were 2.7, 2.9 and 3.1, respectively; the mean ICA/muscle contrast ratios were 1.58, 1.55 and 1.63, and those of IJV/ muscle 1.65, 1.59 and 1.59. There was no significant difference between visual and quantitative assessment in any group. The results suggest that 0.75 ml/kg of contrast medium appears sufficient for vascular opacification for head and neck lesions when the CT scan can be completed in about 120 s.

Adolescent↗
PubMed1997

An experimental study of embolic effect according to infusion rate and concentration of suspension in transarterial particulate embolization.

RATIONALE AND OBJECTIVES: The authors evaluate the embolic effect according to infusion rate and concentration of particulate suspension, focusing on arterial occlusion level. METHODS: The renal arteries of 14 rabbits were embolized with 150 to 250 microns polyvinyl alcohol (PVA) particles, divided into four groups according to two different infusion rates (1 mg/second and 0.1 mg/second) and two different concentrations of suspension (10 mg/mL and 2.5 mg/mL). Arteriograms obtained immediately and a week after embolization were assessed for occlusion level. For the nephrograms obtained a week after embolization, the opacifying areas were graded from 0 to 4. Median coronal sections of each kidney specimen were investigated for the presence of peripheral infarct grossly and for the presence of PVA particles in the small artery microscopically. RESULTS: Arteriograms showed various occlusion levels. Using a 0 to 4 grading system, the opacifying area of the nephrogram obtained 1 week after embolization was noted to be smaller in the low infusion rate group (P < 0.05). In gross and microscopic pathologic examination, the number of cases with peripheral infarct or PVA particles in the small artery (< 300 microns) was greater in the group with the low infusion rate and low concentration (P < 0.05). CONCLUSIONS: In transarterial particulate embolization, slower infusion of more diluted suspension provides for a more distal arterial occlusion.

Animals↗
PubMed1997

Fibrosing inflammatory pseudotumors of the central skull base.

The most important step in the differential diagnosis of mass lesions of the central skull base is to rule out malignant neoplasms. However, nonneoplastic lesions, such as infections or nonspecific inflammatory lesions of the skull base, can mimic malignant processes. In this study, the authors analyzed seven cases of nonneoplastic noninfectious mass-forming lesions involving the central skull base. In most cases, malignant processes were suspected at the initial phase of diagnostic work-up, but subsequent histologic examinations revealed that these lesions consisted of inflammatory cells and fibrosis without neoplastic cells. Common manifestations were pain and other neurological symptoms related to the involved anatomical sites. A variety of neurological dysfunctions of the cranial nerves not including the olfactory and spinal accessory nerves were observed. No patient developed separate lesions outside the head and neck region. After the pathologic diagnosis, most of the patients were treated with oral steroid therapy, with initial doses of prednisolone, 60 to 100 mg/d. It was difficult to relate responsiveness to steroid therapy with the histologic degree of sclerosis, fibrosis, or chronicity of the disease in these cases. Otolaryngologists should be aware of this disease when making treatment decisions for their patients with skull base lesions.

Adult↗
PubMed1997

Brain abscess and brain tumor: discrimination with in vivo H-1 MR spectroscopy.

PURPOSE: To determine the ability to differentiate brain abscess from cystic or necrotic brain tumor with hydrogen-1 magnetic resonance (MR) spectroscopy. MATERIALS AND METHODS: H-1 MR spectroscopy was prospectively performed in seven consecutive patients with pyogenic brain abscess and in seven consecutive patients with necrotic or cystic brain tumor (five patients with glioblastoma and one each with pilocytic astrocytoma and metastasis from lung cancer) in whom radiologic images depicted ring-shaped areas of contrast material enhancement (indicative of a cystic or necrotic mass). Assignment of resonance peaks to metabolites was based on reports in the literature. RESULTS: In six of seven patients with abscess, there were various resonances attributed to lactate, valine, alanine, leucine, acetate, succinate, and unidentified metabolites (2.2, 2.9, 3.2, 3.4, and 3.8 ppm). In six of seven patients with tumor, there was only a resonance attributed to lactate. One patient with a tumor had an unidentified peak at 0.9 ppm (presumably attributed to lipid) in addition to the peak attributed to lactate. CONCLUSION: Spectral patterns from in vivo H-1 MR spectroscopy may permit differentiation of brain abscess from necrotic or cystic tumor.

Adult↗
PubMed1996

Cloning and characterization of cDNAs coding for heavy and light chains of a monoclonal antibody (MabA34) specific for human plasma apolipoprotein A-I.

We have determined the nucleotide (nt) sequences encoding the heavy (H)- and light (L)-chains of the Fab fragment of a murine monoclonal antibody, MabA34 (gamma1, kappa), which is specific for human plasma apolipoprotein A-I of high-density lipoproteins. The variable (V) regions of the H- and L-chains were revealed to be members of mouse H-chain subgroup II(A) and kappa L-chain subgroup II, respectively. A few unusual amino acids in the V region of the H-chain, and nt residues probably introduced by somatic mutations from germline genes were also identified.

Amino Acid Sequence↗
PubMed1996

Cloning and characterization of cDNAs coding for heavy and light chains of a monoclonal antibody (MabB23) specific for human plasma apolipoprotein B-100.

We have determined the nucleotide sequences encoding the heavy and light chains of the Fab fragment of murine monoclonal antibody MabB23(gamma2b,lambda), which is specific for human plasma apolipoprotein B-100 of low-density lipoproteins. The sequence analyses revealed that the variable regions of the heavy and light chains are members of mouse heavy-chain subgroup I(B) and lambda light-chain, respectively. A few unusual amino acids in the framework and constant regions of the heavy-chain were also noticed.

Amino Acid Sequence↗
PubMed1996

Aspergillus sinusitis: clinical aspects and treatment outcomes.

Seventy-two cases of Aspergillus sinusitis were analyzed during a period of 14 years from January 1980 through October 1993. There were 60 cases of primary type and 12 cases of secondary type. The maxillary and ethmoid sinuses were most commonly affected in both primary and secondary types. The sphenoid sinus was commonly involved in secondary type. Fourteen (23%) cases of primary type and 4 (33%) cases of secondary type demonstrated sinus wall destruction on computed tomography or magnetic resonance images. Seventy percent of primary type and all cases of secondary type showed focal or diffuse areas of increased attenuation in the soft tissue mass on computed tomography scans. Sixteen cases assessed by magnetic resonance imaging showed decreased signal intensities on T1-weighted images and markedly reduced signal intensities on T2-weighted images. Fifty-nine (98%) of 60 cases of primary type were noninvasive, and 1 was invasive. In secondary type, 10 (83%) of 12 patients had noninvasive disease. The most common coexisting disease in secondary aspergillosis was diabetes mellitus. Thickened mucosa with necrotic brownish green material, which was the most common finding in both types, was found in 33 patients with primary type and in 5 with secondary type. Surgery was performed in most cases, among which 4 patients received chemotherapy after surgery with amphotericin B with or without flucytosine. All patients were cured without recurrence during a mean follow-up period of 13 months.

Adolescent↗
PubMed1996

Laryngeal tuberculosis: CT findings.

OBJECTIVE: The purpose of this study was to evaluate the CT findings of laryngeal tuberculosis (TB). SUBJECTS AND METHODS: CT scans, laryngoscopic examinations, and chest radiographs of 12 patients (21-63 years old) with histologically (n = 8) or bacteriologically (n = 4) confirmed laryngeal TB were retrospectively reviewed. RESULTS: Bilateral diffuse thickening of the vocal cords and diffuse thickening and increased density of the aryepiglottic folds and paralaryngeal tissues were present in all patients. Diffuse thickening of the epiglottis was observed in seven patients. In four patients, a focal mass was noted in the anterior portions of the vocal cords (n = 3) or tip of the epiglottis (n =1). Destruction or sclerosis of cartilage was not found. Subglottic extension of the lesion was suspected in only one patient. Enlarged cervical lymph nodes were found in five patients. On laryngoscopic examinations, swelling of the vocal cords (n = 12) or epiglottis (n = 6) was present in all patients and was bilateral in nine patients. Vocal cord mobility was impaired in only one patient. Radiographic findings consistent with active pulmonary TB were present in all patients. CONCLUSION: Although the CT appearances of laryngeal TB are not specific, the possibility of laryngeal TB should be raised when bilateral and diffuse laryngeal lesions are encountered without destruction of the laryngeal architecture in patients with pulmonary TB.

Adult↗
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

Characterization of a murine-human chimeric antibody with specificity for the pre-S2 surface antigen of hepatitis B virus expressed in baculovirus-infected insect cells.

We have produced and characterized a murine-human chimeric antibody with specificity for the pre-S2 surface antigen of hepatitis B virus (HBV) in baculovirus-infected insect cells. Recombinant baculovirus carrying the cDNA coding for the heavy or light chain of the chimeric antibody was constructed and co-infected into insect cells. The chimeric antibody (BV-S2) expressed in the cells was purified by an affinity chromatography on Protein A-Sepharose 4B column and characterized by N-terminal amino acid sequencing, affinity determination for pre-S2 peptide, endoglycosidase digestion and Clq binding assay, which were then compared with those of the chimeric antibody H69K that has the same amino acid sequence as BV-S2, but produced from transfected murine myeloma cells. The N-linked glycosylation of the BV-S2 antibody was also analyzed by culturing the baculovirus-infected cells in the presence of tunicamycin. The results showed that the BV-S2 was secreted following correct removal of the leader peptides, contained N-linked carbohydrate at the heavy chain, and had the same binding affinity and Clq binding ability as H69K, suggesting that the BV-S2 chimeric antibody is functional and thus may be useful in the prevention of HBV infection.

Animals↗
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

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

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

Cloning and characterization of cDNAs coding for heavy and light chains of a monoclonal antibody specific for the S antigen of hepatitis B virus.

The nucleotide (nt) sequences encoding the variable regions of the heavy and light chains of a murine monoclonal antibody (mAb) have been determined. The mAb recognizes a disulfide-bond-dependent conformational epitope on the hepatitis B virus surface antigen. The sequence analyses revealed that the variable regions of the heavy and light chains are members of mouse heavy-chain subgroup II(A) and kappa light-chain subgroup III, respectively.

Amino Acid Sequence↗