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Biomedical subjects

B K Cho

Publications and source records attributed to B K Cho.

At least 19 recordsLinked to original sources
PubMed2001

CD8(-) T cell transfectants that express a high affinity T cell receptor exhibit enhanced peptide-dependent activation.

T cells are activated by binding of the T cell receptor (TCR) to a peptide-major histocompatibility complex (MHC) complex (pMHC) expressed on the surface of antigen presenting cells. Various models have predicted that activation is limited to a narrow window of affinities (or dissociation rates) for the TCR-pMHC interaction and that above or below this window, T cells will fail to undergo activation. However, to date there have not been TCRs with sufficiently high affinities in order to test this hypothesis. In this report we examined the activity of a CD8-negative T cell line transfected with a high affinity mutant TCR (K(D) = 10 nM) derived from cytotoxic T lymphocyte clone 2C by in vitro engineering. The results show that despite a 300-fold higher affinity and a 45-fold longer off-rate compared with the wild-type TCR, T cells that expressed the mutant TCRs were activated by peptide. In fact, activation could be detected at significantly lower peptide concentrations than with T cells that expressed the wild-type TCR. Furthermore, binding and functional analyses of a panel of peptide variants suggested that pMHC stability could account for apparent discrepancies between TCR affinity and T cell activity observed in several prior studies.

Antigen Presentation↗
PubMed2001

Childhood meningioma: unusual location, atypical radiological findings, and favorable treatment outcome.

OBJECTS: To investigate the characteristics of childhood meningioma, especially, locations, radiological findings, pathological features (including proliferative potential) and outcome, 11 children with meningiomas were retrospectively analyzed. RESULTS: Unusual location, large size, frequent calcification, and cyst formation were characteristic radiological findings. Gross total resection was achieved in 8 patients, and there was recurrence in 2. Gamma knife radiosurgery was performed on residual and recurrent tumors. MIB-1 indices tended to be high in large tumors. Nine patients had a Karnofsky Performance Scale of more than 70 during the follow-up period of 10 months to 19.5 years. Surgical treatment rendered 4 of 5 epileptic patients seizure free. The childhood meningiomas examined had unusual locations, atypical radiological findings, and various proliferative potentials. CONCLUSIONS: Complete resection is the treatment of choice. Gamma knife radiosurgery can be a good alternative for residual tumors and small recurrent tumors. The outcome of childhood meningiomas is good after surgery.

Adolescent↗
PubMed2001

Is the re-closure of surgically induced open neural tube defect the repetition of primary neurulation? An experimental study with chick embryos.

It is well known that surgically induced open neural tube defects (ONTDs) tend to re-close in early embryonic stages. To investigate whether the process of re-closure is a repetition of primary neurulation, the morphological changes of surgically induced ONTDs were chronologically examined in early chick embryos. Longitudinal incisions of 3-somite length were made in the neural tubes of chick embryos at Hamburger and Hamilton stage 18 or 19. About half of the embryos showed complete closure of the skin on surgical microscopic examination. The re-closed neural tubes showed no remarkable differences from the controls on histological examination. The process of re-closure involved a zipper-like (ventral to dorsal) closure in the transverse sections of neural tubes. The results indicate that the re-closure of surgically induced ONTDs does not repeat the process of natural primary neurulation.

Age Factors↗
PubMed2001

Intramedullary immature teratoma in a young infant involving a long segment of the spinal cord.

Intramedullary teratoma is a rare lesion, located in the majority of cases in the lumbosacral area, and such lesions involving an extensive area of the spinal cord in young infants have seldom been reported. We present the case of a 3-month-old girl with an intramedullary spinal immature teratoma extending from C-5 to T-12, which was totally removed. The patient had suffered from paraplegia for 15 days, after which spinal MRI revealed a heterogeneously enhancing intramedullary lesion. Biopsy of the lesion demonstrated mature intestinal tissue. After total removal of the tumor, paraplegia and sphincter disturbances improved. Intramedullary teratoma should be included in the differential diagnosis of holocord tumors in young infants with rapidly progressing symptoms and if found should be radically excised. This case also emphasizes the importance of histological diagnosis and demonstrates the possibility of neurological recovery even in the case of paraplegia lasting for more than 1 month in a young infant.

Diagnosis, Differential↗
PubMed2001

Low incidence of TEL/AML1 fusion and TEL deletion in Korean childhood acute leukemia by extra-signal fluorescence in situ hybridization.

TEL/AML1 fusion in acute leukemia results from cryptic translocation of chromosome 12 and 21, the presence of which suggests a favorable prognosis. The incidence of TEL/AML1 fusion in B-lineage ALL is approximately 25%, but the incidence in Korea has not yet been reported. To investigate the incidence of TEL/AML1 fusion and TEL deletion, bone marrow specimens from 77 Korean children with newly diagnosed acute leukemia were analyzed by FISH. We applied extra-signal FISH to discriminate a true TEL/AML1 fusion from a false-positive fusion signal. To determine the cut-off value of the TEL/AML1 fusion signal, 20 normal bone marrow specimens and 28 normal peripheral blood specimens were also analyzed. The frequency of patients with TEL/AML1 fusion was 13.3% (4 cases) among 30 B-lineage ALL and 9.5% among 42 ALL. One TEL/AML1 fusion-positive patient was also found among 4 acute biphenotypic leukemias. TEL/AML1 fusion was not found in any samples from patients with T-lineage ALL or AML. The incidence of TEL deletion was 6.7% (2 cases) among 30 B-lineage ALL and 4.8% among 42 ALL. The incidences of TEL/AML1 fusion and TEL deletion in Korean children with acute leukemia appear to be lower than those in other countries, suggesting a racial difference.

Core Binding Factor Alpha 2 Subunit↗
PubMed2001

Differences in antigen recognition and cytolytic activity of CD8(+) and CD8(-) T cells that express the same antigen-specific receptor.

CD8(+) and CD8(-) T cell lines expressing the same antigen-specific receptor [the 2C T cell receptor (TCR)] were compared for ability to bind soluble peptide-MHC and to lyse target cells. The 2C TCR on CD8(-) cells bound a syngeneic MHC (K(b+))-peptide complex 10-100 times less well than the same TCR on CD8(+) cells, and the CD8(-) 2C cells lysed target cells presenting this complex very poorly. Surprisingly, however, the CD8(-) cells differed little from CD8(+) cells in ability to bind an allogeneic MHC (L(d+))-peptide complex and to lyse target cells presenting this complex. The CD8(+)/CD8(-) difference provided an opportunity to estimate how long TCR engagements with peptide-MHC have to persist to initiate the cytolytic T cell response.

Animals↗
PubMed2001

Dependence of lymphopenia-induced T cell proliferation on the abundance of peptide/ MHC epitopes and strength of their interaction with T cell receptors.

Factors that affect naive T cell proliferation in syngeneic lymphopenic hosts were investigated. 2C T cell receptor (TCR) transgenic T cells lacking both CD8 and CD4 survived but hardly proliferated. Proliferation of CD8(+) 2C cells was proportional to the abundance of cognate peptide/MHC complexes and was severely inhibited by injection of anti-CD8 antibody. Weakly reactive self-peptides slightly enhanced CD8(+) 2C cell proliferation whereas a potent agonist peptide promoted much more rapid proliferation, but inflammation-stimulating adjuvant had only a small effect on the rate of cell proliferation. The findings suggest that under uniform lymphopenic conditions, the widely different rates of proliferation of T cells expressing various TCR, or the same TCR in the presence or absence of CD8, reflect the strength of interaction between TCR and MHC associated with particular self-peptides.

Animals↗
PubMed2001

Gangliocytoma of the spinal cord: a case report.

We present a case of intramedullary spinal gangliocytoma in a 7-year-old girl who presented with scoliosis and progressive weakness of both legs. The tumour involved the whole spinal cord and medulla oblongata and was composed of inner cystic and outer solid components. On MRI, the solid portion of the lesion showed strong enhancement at the thoracolumbar level and mild enhancement at the cervical and medullary levels. Histological examination of the surgical specimen showed neoplastic ganglion cells arranged irregularly in benign normocellular glial background, which made a diagnosis of gangliocytoma.

Female↗
PubMed2001

Intractable epilepsy associated with brain tumors in children: surgical modality and outcome.

OBJECTS: The aim of this study was to evaluate the role of surgical modality in children with brain tumors and intractable epilepsy. METHODS: Twenty-three patients who were treated for brain tumors and intractable epilepsy between January 1985 and March 1998 were retrospectively reviewed. The most common tumors were dysembryoplastic neuroepithelial tumors (n=9), oligodendrogliomas (n=6), and gangliogliomas (n=5). Six patients exhibited cortical dysplasia. The mean duration of follow-up was 43.4 months (range 12 to 125 months). Seizure outcome was more favorable (Engel's classes I and II) in patients with a complete resection of tumor (14/14 vs 6/9 for incomplete resection; P<0.05). There was no significant difference in seizure outcome between lesionectomy (n=13) and epilepsy surgery (n=10). The likelihood of requiring postoperative antiepileptic drugs was not influenced by the extent of resection or type of surgery. CONCLUSIONS: On the basis of this study, we conclude that the complete resection of these tumors can be an appropriate initial treatment for children with brain tumors who experience intractable epilepsy.

Adolescent↗
PubMed2001

Radical excision of pediatric craniopharyngioma: recurrence pattern and prognostic factors.

The purpose of our study was to investigate the pattern of recurrence and the prognostic factors for recurrence of pediatric craniopharyngiomas after radical excision. A series of 36 patients with craniopharyngiomas (21 boys and 15 girls; age range 1-15 years; mean 7.3 years) were reviewed. All patients had undergone radical excision without radiotherapy. The mean follow-up period was 52 months (range 1-149 months). Tumors recurred in 14 patients within 83 months (mean 31.4 months). The overall 5-year recurrence-free survival rate was 55%. Regular neuroimaging follow-up detected tumor recurrence while the lesions were still small before symptoms developed (P<0.05). At the first surgical procedure, the optic nerve/chiasm (n=23) was the most common adhesion site. The most frequent sites of recurrence were the optic nerve/chiasm (n=6) and the pituitary fossa (n=6). Tumor location was the single significant clinical predictor of recurrence. The 5-year recurrence-free survival rate was 39% for those who had an intrasellar tumor component and 81% for those who did not (P<0.05). The Ki-67 labeling indices (LIs) of primary tumors did not have prognostic value for recurrence. Recurrent tumors tended to have higher Ki-67 LIs than their primary counterparts. On the basis of this study, we concluded that craniopharyngiomas with intrasellar components should be followed cautiously and the necessity for regular follow-up should be emphasized, even when the tumor is "totally" resected.

Adolescent↗
PubMed2001

External compression of bronchus by aneurysm from divided major aortopulmonary collateral artery after unifocalization.

The right ventricle to pulmonary artery connection with an extracardiac conduit, left pulmonary artery reconstruction, ligation of patent ductus arteriosus, and take-down of right Blalock--Taussig shunt were performed on a 1-year-8-month-old boy who had pulmonary atresia, ventricular septal defect, patent ductus arteriosus, and major aortopulmonary collateral arteries. He previously underwent the unifocalization and right modified Blalock--Taussig shunt at 9 months of age. He repeatedly had a difficulty in weaning from the mechanical ventilator. After removing the aneurysm from the divided major aortopulmonary collateral artery that compressed the left main bronchus externally, it was possible to wean him from the mechanical ventilator.

Aortic Aneurysm↗
PubMed2001

Biological behavior and tumorigenesis of subependymal giant cell astrocytomas.

In spite of the benign nature of subependymal giant cell astrocytomas (SEGAs), some show massive hemorrhage, rapid growth, and tumor recurrence. This led us to investigate the biological behavior, cell dynamics, and tumorigenesis of SEGAs. All patients (4 men and 3 women; age range, 6-27 years; mean, 13.6 years) had features of tuberous sclerosis complex and obstructive hydrocephalus. One patient had intratumoral bleeding. In two patients, sequential neuroimaging showed a subependymal nodule growing to become a SEGA. All underwent surgical resection without radiation therapy. One tumor recurred and was treated surgically. There were no postoperative deaths. The presence of cytologic atypia, mitoses and vascular proliferation had no implication in terms of the clinical course. MIB-1 labeling indices were low (mean, 0.9), indicating low proliferative potential. Unexpectedly, bcl-2 staining was sparse and bax staining predominated in majority of cases. However, the mean value of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling index was low. Immunohistochemically, tumors were positive for both glial and neuronal markers. In the majority of our cases, the expression of p53 was low. Only one tumor was focally positive for tuberin. SEGAs have low proliferative potential and apoptotic activity, and exhibit features of mixed glial-neuronal differentiation. In contrast to p53, tuberin is suggested to be the tumor suppressor in this tumor.

Adult↗
PubMed2001

Contact dermatitis in Korean dental technicians.

The high risk of occupational contact dermatitis in dental personnel are well accepted throughout the world. There are few reports concerning occupational skin disease in dental personnel in Korea. The purposes of this study were to investigate the frequency, characteristics and causative factors of contact dermatitis in Korean dental technicians. Recording of personal history, physical examination and patch tests with the Korean standard series and dental screening series were performed in 49 dental technicians. Most of the subjects were exposed to a variety of compounds, including acrylics, metals, plaster, alginate, etc. 22 (44.9%) subjects had contact dermatitis, present or past, and the site involved was the hand in all 22. The most common clinical feature of hand dermatitis was itching (77.3%); scaling, fissuring and erythema were other common clinical features. Metals, including potassium dichromate (24.5%), nickel sulfate (18.4%), mercury ammonium chloride (16.3%), cobalt chloride (12.2%) and palladium chloride (10.2%), showed high positive rates in patch test results of 49 dental technicians. 7 positive reactions to the various acrylics were found in 3 subjects. In our study, the frequency and clinical features of the contact dermatitis showed a similarity to other reports, though the patch test results were somewhat different; a higher patch-positive reaction to metals and a relatively lower patch-positive reaction to acrylics than the patch test results reported in Europe.

Adult↗