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Biomedical subjects

B K Cho

Publications and source records attributed to B K Cho.

At least 73 records · Page 4Linked to original sources
PubMed1999

Cerebrospinal fluid shunt infection in children: efficiency of management protocol, rate of persistent shunt colonization, and significance of 'off-antibiotics' trial.

To evaluate the efficiency of our management protocol, 33 pediatric cases of bacteria-infected cerebrospinal fluid shunt were reviewed. The causative organism was staphylococcus in 23 patients. In 23 patients, shunt infection was managed according to the protocol. The complexity of the shunt system did not prolong hospitalization. Unchanged but externalized tubings showed persistent colonization despite adequate antibiotics in 10 of 21 patients. Staphylococcal infection was oxacillin-resistant in 7 of 19. The efficiency of an 'off-antibiotics' trial was minimal. Further modification of the protocol is expected to enhance efficiency of the management.

Adolescent↗
PubMed1999

A simple method of predicting hormonal outcome in children with intracranial germinoma.

Even a small intracranial germinoma (GE) frequently provokes pituitary hypofunction. We evaluated the relationships between preoperative hormonal status and hormonal outcome and between size of suprasellar mass and hormonal outcome in 22 children with intracranial pure GE to determine whether or not these can reflect the degree of hypothalamo-pituitary axis destruction. Preoperative hormonal status was graded from I to IV according to the serum prolactin level (s-PRL) and thyroid function (TF). The hormonal outcome was estimated by the type and the number of hormonal replacement medications taken on the basis of the triple load test and endocrinological examinations at the time of the last follow-up (median period: 43 months). Fifteen of the 22 patients had suprasellar lesions. All 13 patients who had diabetes insipidus (DI) at presentation needed desmopressin acetate (DDAVP) during the follow-up period. The correlation between increment of preoperative grade and the increment in the number of hormones to be replaced was statistically significant (P<0.05). This preoperative grading was a more reliable predictor than the size of suprasellar tumor. In conclusion, preoperative grading by s-PRL and TF test is useful for the prediction of posttreatment hormonal replacement in children with intracranial pure GE.

Adolescent↗
PubMed1999

Treatment of intracranial nongerminomatous malignant germ cell tumor in children: the role of each treatment modality.

To investigate the role of surgical tumor resection, radiotherapy and chemotherapy, the outcome of treatment in 17 children with nongerminomatous malignant germ cell tumor (NG-MGCT) was reviewed. The median follow-up period was 38 months after diagnosis, and the overall 3-year survival rate was 75%. Eleven patients who underwent craniospinal radiation (CSRT) did not receive chemotherapy. In 4 of them more than 90% of the tumor was removed, and they were free of disease at 16, 30, 93 and 111 months after surgery. Among the other 7, who did not undergo tumor resection (n=5) or had considerable residual tumor (n=2), 2 were disease-free at 73 and 88 months after diagnosis, and 5 died of recurrences. Of 6 patients who received cisplatin and etoposide chemotherapy in addition to CSRT, none showed intracranial recurrence, regardless of the extent of removal. The authors believe that multimodal treatment is the preferred choice and that chemotherapy plays an important role, especially when a significant amount of tumor remains after surgery. CSRT plays a major role at least in some patients. If chemotherapy is not feasible, radical removal plus CSRT seems to be an alternative.

Adolescent↗
PubMed1999

Congenital glioblastoma diagnosed by fetal sonography.

Congenital brain tumors are very rare, and 2-9% of them are accounted for by glioblastomas. We encountered a case of congenital glioblastoma detected at the 39th week of gestation by fetal sonography, which revealed a large echogenic mass in the left temporo-parietal area of the fetal brain with significant midline shift and dilatation of the contralateral lateral ventricle. A detailed sonogram obtained 7 h later showed that the mass had increased in size, and this suggested an expanding hematoma. An emergency cesarean section was performed. Postnatal MRI demonstrated an enhancing mass with a large hematoma. Biopsy revealed a malignant brain tumor. Further management was refused and the boy died 6 days after birth. The postmortem pathological diagnosis was glioblastoma. When fetal sonography demonstrates an echogenic mass, a congenital brain tumor should be considered. The mode of delivery should be determined by the nature of the mass and the condition of the fetus.

Adult↗
PubMed1999

Neurenteric cyst: its various presentations.

Neurenteric (NE) cyst is an uncommon developmental lesion lined with epithelium of endodermal origin. To investigate the clinical manifestation and response to surgery, we retrospectively analyzed eight cases of NE cyst that has been confirmed by surgery. Four were in children. The duration of follow-up ranged from 2 to 105 (mean 38) months. One cyst was in the ventral portion of the posterior cranial fossa and the other seven were on the spinal cord. The chief complaints were motor weakness (5), pain (2), and voiding difficulty (1). In one child and three adults, the duration of symptoms was more than 3 years. Children tended to show rapid progression and excellent recovery after surgery. Although total removal of cyst was possible only in two cases, there was no recurrence. The presentation of an NE cyst may be insidious. Clinical suspicion is important for an early diagnosis and better outcome. Because of the benign course after subtotal excision, too-aggressive removal of the lesion should be avoided.

Adult↗
PubMed1999

Supratentorial primitive neuroectodermal tumor in children: clinical features, treatment outcome and prognostic factors.

To investigate clinical features, treatment outcome and prognostic factors of pediatric supratentorial primitive neuroectodermal tumors(ST-PNETs), 28 ST-PNET cases were retrospectively analyzed. The prognostic importance of age, sex, size of tumor, M stage, extent of surgical resection, histological features, immunohistochemical labelling indices (Ki-67, p53), and apoptotic index were assessed. The mean age at diagnosis was 6.8 years, and the male-to-female ratio was 18:10. The presenting symptoms in 22 cases were increased intracranial pressure and focal neurological deficits. Gross total resection was achieved in 17 cases, near-total (>90%) resection in 3, and subtotal in 7; biopsy was performed in 1 case. The mean duration of follow-up was 37 months. For 25 patients who completed planned adjuvant therapy, the 3-year survival rate was 73%. Univariate analysis showed that the presence of tumor necrosis (P=0.002) and extent of resection (P=0.04) correlated with survival. Patients with a high Ki-67 labelling index (>10%) tended to have shorter survival (P=0.095). In multivariate analysis, tumor necrosis showed statistical significance(P=0.03).

Adolescent↗
PubMed1999

Outcomes of medical treatment of neurocysticercosis: a study of 65 cases in Cheju Island, Korea.

BACKGROUND: Although cysticidal drugs hasten the death and disappearance of the parasite, the long-term prognosis of NCC is still not satisfactory. METHODS: In this study, 65 patients with active neurocysticercosis (NCC) treated with praziquantel or albendazole were retrospectively reviewed to evaluate radiological and clinical outcome. According to worm location, patients were divided into two groups: parenchymal (n = 42) and extraparenchymal NCC (n = 23). The average duration of follow-up was 23 months. RESULTS: In terms of cysticidal effectiveness (73% vs. 50%), seizure control (60% vs. 43%) and symptomatic improvement of non-seizure patients (64% vs. 44%), the outcome of treatment was better in the parenchymal NCC than in the extraparenchymal. Repeated cysticidal treatment was needed in 26% of parenchymal and 39% of extraparenchymal NCC. After treatment, 38% of parenchymal NCC complained of seizure and 35% suffered from headache. Likewise, 27% and 36% of extraparenchymal NCC complained of seizure and headache, respectively. During the follow-up, 7 of 30 patients without initial seizure developed new seizures after medical treatment. CONCLUSION: Despite the development of cysticidal drugs, a considerable number of patients suffer from late neurologic sequelae such as seizure and headache. Therefore continuous attention should be given to the patients after cysticidal treatment. Prevention by health education is emphasized.

Adolescent↗
PubMed1999

Congenital annular multiple fibrofolliculomas occurring with deformity of the ear and ventricular septal defect.

We describe a 5-year-old girl who had multiple fibrofolliculomas with an unusual annular configuration, present since birth, localized to the mid-back. She had no family history of similar skin lesions. Examination showed a depigmented patch on her left buttock and other congenital anomalies, i.e. deformity of the auricle of the ear and ventricular septal defect. There has been no previous report of congenital multiple fibrofolliculomas occurring with congenital malformations such as deformity of the auricle of the ear and ventricular septal defect. The congenital occurrence and unusual configuration of the lesions in our patient may suggest a naevoid origin for these tumours.

Child, Preschool↗
PubMed1999

Evaluation of the degree of cross-linking in UV irradiated porcine valves.

A porcine heart valve was irradiated by Ultraviolet (UV) rays (10 W, 254 nm) for 2, 4, 8 and 24 hours at 4 degrees C to cross-link the structural collagen matrix. The degree of cross-linking was evaluated by assaying the released amount of hydroxyproline (Hyp) from the matrix, and comparing it with the positive controls of valves treated by glutaraldehyde (GA) solution (0.625 wt%) and the negative controls of non-treated fresh valves. The undigested weight ratio of the specimens increased by increasing the UV irradiation time. The undigested weight of the leaflets, tunica interna and tunica externa of the fresh, GA-treated and UV-irradiated specimens after collagenase digestion was compared. As UV irradiation increased, the amount of released hydroxyproline was gradually decreased until 8 hours of irradiation, after which the released hydroxyproline-reduction occurred slightly until 24 hours of irradiation time in this system. A total 47.68% of the hydroxyproline in the valve was cross-linked by UV irradiation after 24 hours, while 73.74% of the hydroxyproline in the positive control was crossed-linked. Light microscopic observation revealed that the typical crimp pattern of collagen fibers decreased and was rearranged into a dense flattened pattern as the UV irradiation induced interfibrilar cross-linking. GA-treated valves demonstrated a denser matrix pattern than the UV-irradiated specimens. Cross-linked collagenous tissue prepared by UV irradiation would be useful for improving durability and reducing the disadvantages related to using a chemical cross-linking agent.

Animals↗
PubMed1999

Viability and enzymatic activity of cryopreserved porcine heart valve.

Fibroblast viability of a natural tissue valve for replacing a defective heart valve through allograft or xenograft has been suggested to affect its clinical durability. In this study, the cell viability and enzymatic activity of porcine heart valve leaflets were examined in regard to concerning to the preservation process [variable warm ischemic time (WIT), cold ischemic time (CIT), and cryopreservation]. Porcine heart enblocs were obtained and valve dissection was performed after 2, 12, 24, or 36 hours, in respective groups A, B, C, and D, as WIT. Each group was stored for 24 hours as CIT and cryopreserved. Leaflets were dissected from a valved conduit after each process, and cell viability and enzymatic activity in the leaflet were investigated using trypan blue staining and API ZYM kits. WIT extension significantly decreased fibroblast viability (p < 0.05, 92.25 +/- 2.7% at 2 hours, 84.9 +/- 6.7% at 12 hours, 57.0 +/- 10.2% at 24 hours, 55.9 +/- 7.9% at 36 hours), while CIT for 24 hours was also influenced significantly (p < 0.05), whereas cryopreservation demonstrated no effect on cellular viability. In enzyme activity observation, several enzymes related to lipid or nucleotide degradation (esterase, esterase lipase, particularly phosphatase, phosphohydrolase) were remarkably changed following the valve-fabrication process. After 24 hours CIT, these enzymatic activities in groups B, C and D significantly increased, but the activities decreased after cryopreservation. Particularly, both the viability and enzymatic activity showed remarkable changes after CIT in group B (WIT = 12 hours). These results suggest that WIT is more important than CIT in maintaining viability of the valve, and that completing all the cryopreservation process within 12 hours after acquisition is recommended.

Animals↗
PubMed1998

A yeast surface display system for the discovery of ligands that trigger cell activation.

Opposing cells often communicate signalling events using multivalent interactions between receptors present on their cell surface. For example, T cells are typically activated when the T cell receptor (TCR) and its associated costimulatory molecules are multivalently engaged by the appropriate ligands present on an antigen presenting cell. In this report, yeast expressing high cell-surface levels of a TCR ligand (a recombinant antibody to the TCR Vbeta domain) were shown to act as 'pseudo' antigen presenting cells and induce T cell activation as monitored by increased levels of CD25 and CD69 and by downregulation of cell surface TCR. Similar levels of T cell activation could occur even when a 30-fold excess of irrelevant yeast was present, suggesting that such a yeast display system, by virtue of its ability to present ligands multivalently, may be used in highly sensitive procedures to identify novel polypeptides that interact multivalently with cell surface receptors and thereby trigger specific cellular responses.

Animals↗
PubMed1998

Targeting T cells against brain tumors with a bispecific ligand-antibody conjugate.

High-affinity receptors expressed on the surface of some tumors can be exploited by chemically conjugating the ligand for the receptor and an antibody against immune effector cells, thus redirecting their cytolytic potential against the tumor. Ovarian carcinomas and some brain tumors express the high-affinity folate receptor (FR). In this report, a transgenic mouse model that generates endogenously arising choroid plexus tumors was used to show that folate/anti-T-cell receptor antibody conjugates can direct infiltration of T cells into solid brain tumor masses. An engineered single-chain Fv form of the anti-T-cell receptor antibody KJ16 was conjugated with folate, to produce a bispecific agent that was substantially smaller than most previously characterized bispecific antibodies. Folate conjugation to the antibody increased T-cell infiltration into the tumors by 10- to 20-fold, and significantly prolonged survival of the mice.

Animals↗
PubMed1998

Targeting tumor cells with bispecific antibodies and T cells.

It has been known for some time that mammalian immune systems are capable of eliminating large tumor burdens. Redirecting the immune response of a patient to an established tumor has now become the focus of various therapeutic strategies. In this report, two projects toward this goal are described. The first project involves the development of a transgenic mouse model for T cell directed therapeutics. These mice express specific T cell receptor alpha and beta transgenes on a background in which the recombinational-activating-gene-1 (RAG) has been knocked out. The mice express cytotoxic T cells but not either T helper cells or B cells. Despite these deficiencies, the animals are capable of eliminating tumors that express the appropriate peptide/major histocompatibility complex ligand that is recognized by the alphabeta transgenic T cell receptor. Human tumors grow as transplants in these mice, thereby allowing various agents that redirect the endogenous T cells against human tumors to be tested. The second project involves a description of such agents: bispecific antibodies that simultaneously bind to an immune effector cell and a tumor cell. The bispecific antibody described here consists of folate attached to anti-T cell receptor antibodies, or their fragments. A single-chain Fv coupled with folate can redirect the lysis of human tumor cells that bear the high affinity folate receptor. Preliminary in vivo data showed that the folate/antibody conjugates were also capable of mediating rejection of the human tumor. This transgenic mouse model should now allow the evaluation and optimization of bispecific agents that can redirect a patient's own T cell response.

Amino Acid Sequence↗
PubMed1998

Cell kinetics of surgically induced spinal open neural tube defect in chick embryos.

In an attempt to understand cell kinetics of open neural tube defects (ONTDs) in the embryonic stages, chronological changes of cell proliferation and cell death patterns in the surgically induced spinal ONTDs of chick embryos were investigated using proliferating cell nuclear antigen (PCNA) staining and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL) method. ONTDs were induced at Hamburger and Hamilton stages 17-19. Compared with the control group, the surgery group showed a lower PCNA labeling index for 5 days after surgery and demonstrated more TUNEL-positive cells at 6 h, 3 and 5 days after surgery. Decreased cell proliferation and enhanced apoptosis were seen in the ventral as well as in the dorsal spinal cord. These results partly explain the functional deficits of ONTDs.

Animals↗