Search PubMed⌕ Search

Biomedical subjects

M H Han

Publications and source records attributed to M H Han.

At least 19 recordsLinked to original sources
PubMed2000

Acute bilateral cerebellar infarcts in the territory of posterior inferior cerebellar artery.

The authors report 12 patients with acute bilateral cerebellar infarcts in posterior inferior cerebellar artery (PICA) territory. They found three topographic patterns: A) bilateral medial PICA in six patients; B) unilateral whole + contralateral medial PICA in four; and C) bilateral small multiple in two. Nine patients in Groups A and B had unilateral PICA or vertebral artery disease, and both patients in Group C had bilateral vertebral artery disease. These findings support that unilateral supply to both medial PICA territories may be the most relevant pathogenesis of this syndrome.

Aged↗
PubMed2000

Constitutive activation of cyclin B1-associated cdc2 kinase overrides p53-mediated G2-M arrest.

Recent studies have suggested that p53 regulates the G2 checkpoint in the cell cycle and that this function is required for the maintenance of genomic integrity. In this study, we investigated a regulatory role of p53 specifically in G2-M transition. Human bladder carcinoma cells lacking functional p53 were synchronized at G1-S, which is preceded by p53-mediated G1 arrest. p53 expression in the synchronized cells was induced by infection with a recombinant adenovirus that encodes p53. After release from the G1-S arrest, the cells progressed to S-phase and G2 but failed to enter mitosis. Biochemical analysis showed that p53 inhibits cell cycle-dependent expression of cdc2 and cyclin B1 and consequently inhibits cdc2 kinase. The role of cyclin B1-associated cdc2 kinase in p53-mediated G2-M arrest was further investigated by expression of both cyclin B1 and cdc2AF, in which inhibitory phosphorylation sites were substituted. The cells expressing both cdc2AF and cyclin B1 showed a constitutive activation of cdc2 kinase during cell cycle progression and passed through G2-M regardless of p53 expression. Therefore, inactivation of cdc2 kinase through cdc2 and cyclin B1 repression is an essential step in p53-mediated G2-M arrest.

CDC2 Protein Kinase↗
PubMed2000

Clinical feature and outcome of pediatric cerebrovascular disease: a neurosurgical series.

To investigate the clinical features and surgical outcome of pediatric cerebrovascular disease (CVD), we retrospectively reviewed 280 children (up to 15 years of age) who underwent neurosurgical procedures for CVD between 1979 and 1998. Open surgery (n=448), endovascular procedures (n=22), and stereotactic radiosurgery (n=14) were the main neurosurgical procedures adopted. Clinical features and surgical outcomes were described according to the etiology of the CVD and the number of years of management. The mean duration of follow-up was 34 months. The mean age was 7.1 years, and the male-to-female ratio was 1.2:1. The most frequent CVD was moyamoya disease (62%). The surgical mortality related to CVD was 0.7%. Eighty-seven percent had Karnofsky Performance Scale scores of more than 70. We demonstrate increasing detection rates and improving outcomes in recent years. The clinical course in this study shows that recovery from CVD in children is good after neurosurgical procedures.

Adolescent↗
PubMed2000

Diffusion-weighted MRI in cystic or necrotic intracranial lesions.

Our purpose was to investigate the signal intensities of cystic or necrotic intracranial lesions on diffusion-weighted MRI (DWI) and measure their apparent diffusion coefficients (ADC). We examined 39 cystic or necrotic intracranial lesions in 33 consecutive patients: five malignant gliomas, seven metastases, two other necrotic tumours, a haemangioblastoma, three epidermoids, an arachnoid cyst, seven pyogenic abscesses, 12 cases of cysticercosis and one of radiation necrosis. DWI was performed on a 1.5 T unit using a single-shot echo-planar spin-echo pulse sequence with b 1,000 s/mm2. The signal intensity of the cystic or necrotic portion on DWI was classified by visual assessment as markedly low (as low as cerebrospinal fluid), slightly lower than, isointense with, and slightly or markedly higher than normal brain parenchyma. ADC were calculated in 31 lesions using a linear estimation method with measurements from b of 0 and 1,000 s/ mm2. The cystic or necrotic portions of all neoplasms (other than two metastases) gave slightly or markedly low signal, with ADC of more than 2.60 x 10(-3) mm2/s. Two metastases in two patients showed marked high signal, with ADC of 0.50 x 10(-3) mm2/s and 1.23 x 10(-3) mm2/s, respectively. Epidermoids showed slight or marked high signal, with ADC of less than 1.03 x 10(-3) mm2/s. The arachnoid cyst gave markedly low signal, with ADC of 3.00 x 10(-3) mm2/s. All abscesses showed marked high signal, with ADC below 0.95 x 10(-3) mm2/s. The cases of cysticercosis showed variable signal intensity; markedly low in five, slightly low in three and markedly high in four.

Brain↗
PubMed2000

A case of guttate psoriasis following Kawasaki disease.

We report a case of guttate psoriasis following Kawasaki disease, in a patient with Staphylococcus aureus demonstrated in a throat swab. We suggest that preceding staphylococcal infection can play a key role in the pathogenesis of some cases of guttate psoriasis, possibly by the production of superantigens.

Disease Progression↗
PubMed2000

Onychomycosis and Trichosporon beigelii in Korea.

BACKGROUND: Onychomycosis is a common superficial fungal infection. Causative organisms in onychomycosis have been extensively studied, but the role of nondermatophytes is controversial. Trichosporon beigelii is a soil and water inhabiting yeast and is occasionally found in the flora normally associated with human skin, mouth, and nails. Several reports in the literature have suggested that T. beigelii is one of the pathogens in onychomycosis. METHODS: We performed a survey of the mycologic laboratory records of patients clinically suspected of having onychomycosis from July 1996 to December 1998. RESULTS: Out of a total of 2591 nail samples examined, 1222 (47.2%) were culture positive, including 262 cases (10.1%) with T. beigelii. The overall positive rate for the KOH mount examination was 58.8%, and in the cases with T. beigelii was 89.1%. Among the age groups, the incidence rate was highest in the fifth decade (26.6%). The most common causative organism of microscopy-positive onychomycosis was Trichophyton rubrum (61.4%); the others in decreasing frequency were T. beigelii (20.4%), Candida spp. (7.3%), Trichophyton mentagrophytes (4.1%), and mixed infection (2.9%). T. beigelii was repeatedly isolated in successive nail cultures from 10 of 20 patients selected from those with T. beigelii nail infection. CONCLUSIONS: T. beigelii was the second most commonly isolated fungus in onychomycosis and had a high positive rate on KOH mount examination of the nails and successive repeated cultures. We suggest that T. beigelii might be a common pathogen of onychomycosis in Korea.

Adolescent↗
PubMed2000

Palliatively treated cerebral arteriovenous malformations: follow-up results.

The purpose of this study was to evaluate the benefits of palliative embolisation of patients with inoperable intracranial AVMs. It involved the analysis of the long-term clinical follow-up results of 27 patients with inoperable intracranial AVMs. Sixteen patients were treated medically and 11 patients received partial embolisation. The mean size of the lesions was 7.2 +/- 2.6 cm, and the mean follow-up period was 99 +/- 44 months (range 52-192 months). There were no significant statistical differences in the sex, age, size, venous drainage pattern, location of the lesions or presented symptoms. The analysis of the long-term clinical follow-up results showed no significant difference in either the risk of haemorrhage or clinical status of the patients in the two treatment groups. Of the 16 patients in the medical treatment group, 8 (50%) showed a clinical improvement, 3 no improvement and 5 (31%) deterioration. Of the 11 patients in the embolisation group, 5 (45.5%) showed clinical improvement, 3 no improvement and 3 (27.3%) deterioration (P = 0.871). Twenty-five percent (4 cases) of patients in the medical group and 45.5% (5 cases) of patients in the embolisation group suffered from haemorrhage during the follow-up period (P = 0.270). Complications related to embolisation occurred in three cases. This comparative study shows that palliative partial embolisation of intracranial AVMs, in all probability does not produce better clinical results than medical treatment.

Adult↗
PubMed2000

In vivo proton magnetic resonance spectroscopy of central neurocytomas.

OBJECTIVE: The authors report on the metabolic features of central neurocytomas observed during in vivo single-voxel proton magnetic resonance spectroscopy. METHODS: Volume-selective single-voxel proton magnetic resonance spectroscopy was performed with a 1.5-T unit using a point-resolved spectroscopy sequence (TR/TE = 2000 ms/135 and 270 ms) to obtain spectra of a single 8-cc voxel. The subjects were five patients in the Department of Neurosurgery of Seoul National University Hospital whose central neurocytomas had been diagnosed histologically. The peak intensities of compounds containing choline (Cho), N-acetylaspartate, creatine/phosphocreatine, and lactate were analyzed. RESULTS: The ratios of Cho to creatine/phosphocreatine and Cho to N-acetylaspartate were significantly higher than ratios in normal brains. A lactate signal was present, and an unidentified signal was also observed at 3.55 ppm, which might have been produced by inositol or glycine. CONCLUSION: A combination of the signal at 3.55 ppm and a prominent Cho peak seems to be a characteristic feature of central neurocytomas. Volume-selective single-voxel proton magnetic resonance spectroscopy could provide additional information to aid in diagnosing this condition.

Adolescent↗
PubMed2000

Carcinoma erysipelatoides originating from stomach adenocarcinoma.

Carcinoma erysipelatoides is an uncommon form of cutaneous metastasis, which is most commonly caused by breast carcinoma, it has rarely been linked to the primary cancers of other organs. We report a 36-year-old woman with carcinoma erysipelatoides originating from a gastric carcinoma. Immunohistochemical and morphologic studies of skin biopsies revealed that the signet ring cells in the dilated lymphatics originated from adenocarcinoma of the stomach.

Adenocarcinoma↗
PubMed2000

MR imaging features of clear-cell meningioma with diffuse leptomeningeal seeding.

Clear-cell meningioma is a rare disease entity showing a more aggressive nature, clinically, than those of other subtypes of meningioma. It occurs in younger persons and commonly in the spinal canal. The recurrence rate has been reported to be as high as 60%. We present a case of clear-cell meningioma in a 17-year-old man in whom initial MR imaging showed localized leptomeningeal enhancement that had progressed into the entire subarachnoid space after surgical resection of the primary tumor.

Adolescent↗
PubMed2000

Neck infection associated with pyriform sinus fistula: imaging findings.

BACKGROUND AND PURPOSE: Acute suppurative neck infections associated with branchial fistulas are frequently recurrent. In this study, we describe the imaging findings of acute suppurative infection of the neck caused by a third or fourth branchial fistula (pyriform sinus fistula). METHODS: Imaging findings were reviewed in 17 patients (11 female and six male patients, 2 to 49 years old) with neck infection associated with pyriform sinus fistula. Surgery or laryngoscopic examination confirmed the diagnoses. Fourteen patients had a history of recurrent neck infection and seven had cutaneous openings on the anterior portion of the neck (all lesions were on the left side). Imaging studies included barium esophagography (n = 16), CT (n = 14), MR imaging (n = 2), and sonography (n = 3). RESULTS: A sinus or fistulous tract was identified in eight of 16 patients on barium esophagograms. In 14 patients, CT studies showed the inflammatory infiltration and/or abscess formation along the course of the sinus or fistulous tract from the pyriform fossa to the thyroid gland. In nine patients, CT scans showed the entire course or a part of the sinus or fistulous tract as a tiny spot containing air. MR images showed a sinus or fistulous tract in two patients, whereas sonograms could not depict a sinus or fistulous tract in three patients. All 17 patients were treated with antibiotics. In one patient, the sinus tract was surgically excised, while 15 patients underwent chemocauterization of the sinus or fistulous tract with good outcome. Follow-up was possible for 16 of the 17 patients. CONCLUSION: When an inflammatory infiltration or abscess is present between the pyriform fossa and the thyroid bed in the lower left part of the neck, an infected third or fourth branchial fistula should be strongly suspected.

Abscess↗
PubMed1999

p53 negatively regulates cdc2 transcription via the CCAAT-binding NF-Y transcription factor.

The p53 tumor suppressor protein regulates the transcription of regulatory genes involved in cell cycle arrest and apoptosis. We have reported previously that inducible expression of the p53 gene leads to the cell cycle arrest both at G(1) and G(2)/M in association with induction of p21 and reduction of mitotic cyclins (cyclin A and B) and cdc2 mRNA. In this study, we investigated the mechanism by which p53 regulates transcription of the cdc2 gene. Transient transfection analysis showed that wild type p53 represses whereas various dominant negative mutants of p53 increase cdc2 transcription. The cdc2 promoter activity is not repressed in cells transfected with a transactivation mutant, p53(22/23). An adenovirus oncoprotein, E1B-55K inhibits the p53-mediated repression of the cdc2 promoter, while E1B-19K does not. Since the cdc2 promoter does not contain a TATA sequence, we performed deletion and point mutation analyses and identified the inverted CCAAT sequence located at -76 as a cis-acting element for the p53-mediated regulation. We found that a specific DNA-protein complex is formed at the CCAAT sequence and that this complex contains the NF-Y transcription factor. Consistently, a dominant negative mutant of the NF-YA subunit, NF-YAm29, decreases the cdc2 promoter, and p53 does not further decrease the promoter activity in the presence of NF-YAm29. These results suggest that p53 negatively regulates cdc2 transcription and that the NF-Y transcription factor is required for the p53-mediated regulation.

Base Sequence↗
PubMed1999

Zn2+ differentially modulates kinetics of GABA(C) vs GABA(A) receptors in carp retinal bipolar cells.

GABA(C) and GABA(A) receptors co-exist in retinal bipolar cells. In the present study the effects of zinc on the kinetics of currents mediated by GABA(C) and GABA(A) receptors were investigated in isolated carp bipolar cells, using whole-cell patch-clamp technique. We observed for the first time that zinc exerted opposite effects on kinetics of the GABA(C) and GABA(A) responses: zinc significantly slowed down activation and desensitization of the GABA(C) response, but accelerated those of the GABA(A) response; zinc dramatically accelerated deactivation of the GABA(C) response, whereas it had no apparent effect on deactivation of the GABA(A) response. These results suggest that zinc may be functionally important in regulating retinal signal transmission.

Animals↗
PubMed1999

Sequential change of MR signal intensity of the brain after manganese administration in rabbits. Correlation with manganese concentration and histopathologic findings.

RATIONALE AND OBJECTIVES: High signal intensity in the basal ganglia on T1-weighted MR imaging has been reported in chronic manganese (Mn) poisoning. However, the exact meaning of the high signal intensity remains unclear: does it result from Mn itself, secondary pathologic changes of the brain tissue, or both? The goal of this study was to evaluate the sequential change of MR signal intensity and to correlate the MR intensity of the globus pallidus and the hypothalamus with the Mn concentration in the blood and the brain tissue, and with the histopathologic findings. METHODS: Ten milligrams per kilogram of Mn was administered once a week for 4 weeks to 14 rabbits. The rabbits in the control group (n = 2) were killed without Mn administration; those in group I (n = 4) were killed 1 day after the completion of Mn administration, those in group II (n = 4) were killed at 4 weeks, and those in group III (n = 6) were killed at 8 weeks. Sequential MR imaging, blood and tissue concentration measurement, and pathologic examination were performed. Sequential changes of the percent contrasts, contrast-to-noise ratios, and T1 relaxation times were analyzed with blood and tissue concentrations and histopathologic findings. RESULTS: The signal intensity of the basal ganglia on T1-weighted imaging was highest 1 day after cessation of Mn administration and sequentially washed out. The contrast, contrast-to-noise ratio, and T1 relaxation time showed significant correlations with blood concentration. Only the T1 relaxation time of the globus pallidus showed a significant correlation with tissue concentration. Histopathologic examination disclosed mild abnormalities in the globus pallidus, thalamus, and hypothalamus. CONCLUSIONS: The high signal intensity on T1-weighted MR imaging presumably indicates mainly the exposure marker of Mn, although mild pathologic findings were observed.

Animals↗
PubMed1999

Craniofacial arteriovenous malformation: preoperative embolization with direct puncture and injection of n-butyl cyanoacrylate.

PURPOSE: To evaluate the use of n-butyl cyanoacrylate (NBCA) for preoperative embolization of craniofacial arteriovenous malformation. MATERIALS AND METHODS: Fourteen patients with craniofacial arteriovenous malformation (forehead [n = 9], deep facial [n = 3], occipital [n = 1], or lip [n = 1] lesion) were treated with injection of NBCA. Forehead lesions were supplied by ophthalmic (n = 6) and/or superficial temporal arteries (n = 7); and facial and scalp lesions, by bilateral internal maxillary (n = 4), facial (n = 2), and/or occipital arteries (n = 1). Lesions were percutaneously punctured with a 20-gauge needle in the area of arteriovenous connection. Direct angiography was performed before and after compression of venous drainage, and NBCA diluted 30%-50% with iodized oil was injected during venous compression. RESULTS: Postembolization arteriograms showed that six lesions were completely devascularized after single or multiple (one to nine) injections, and five were effectively devascularized (> or = 90%). Although three lesions were 60%-70% devascularized after injection, two of these were successfully extirpated with no notable blood loss. In nine patients, the ophthalmic arterial supply had disappeared after embolization. There were no procedure-related complications. CONCLUSION: Direct-puncture embolization with NBCA is an effective and safe technique for preoperative devascularization of craniofacial arteriovenous malformation. For safe and effective devascularization, compression of draining venous channels is thought to be important.

Adolescent↗