Search PubMed⌕ Search

Biomedical subjects

S S Yoon

Publications and source records attributed to S S Yoon.

At least 55 records · Page 3Linked to original sources
PubMed1996

Third ventriculostomy: post-operative ventricular size and outcome.

Reduction in ventricular size after third ventriculostomy often appears minimal. In order to determine if changes in ventricular size are a reliable measure of a functioning ventriculostomy, and which ventricle is more sensitive to this change, we compared pre-operative lateral and third ventricular diameter with serial post-operative axial CT and/or MRI scans in a series of 27 consecutive third ventriculostomies. Of eleven patients with aqueductal stenosis, fifteen with mass lesions and one with a Chiari I, six patients were shunted before 1 month and two refused radiographic follow-up. In the remaining nineteen patients, with an average follow-up of 20 months, the average (s.d.) third ventricular change was -30 (11)% for twelve improved patients, and +13 (18)% for the seven patients without improvement (p < 0.00001). The average (s.d.) lateral ventricular change was -23 (15)% for improved patients, and +5 (21)% for those without improvement (p < 0.005). A decrease in third ventricular size by a least 15% was seen in all significantly improved patients. Similar results were found in 9 patients with scans performed exactly one month post-operatively. Among the aqueductal stenosis patients, factors associated with failure were age > 70 years associated with symptoms of NPH, symptomatic, shunted hydrocephalus since before age 1 year and a history of meningitis. In the remaining patients, failures occurred with a history of meningitis, subdural hematoma, Chiari I malformation or following open tumor surgery or intraventricular AVM rupture. Although both the lateral and third ventricles change in diameter after third ventriculostomy, the third ventricular diameter is more reliable. As early as one month post-operatively, ventricular diameter reflects the clinical outcome of the operation. A decrease in third ventricular diameter by at least 15% was seen in all successful cases and in none of the failures.

Adolescent↗
PubMed1996

Serial measurement of interleukin-6, transforming growth factor-beta, and S-100 protein in patients with acute stroke.

BACKGROUND AND PURPOSE: Cytokine changes in patients with acute stroke have been insufficiently studied. The purpose of this study was to delineate the characteristics of serial changes of serum interleukin-6 (IL-6) and transforming growth factor-beta (TGF-beta) in patients with cerebral infarction and intracerebral hemorrhage. METHODS: We serially (within 24 hours, at day 3, and at day 7) measured the serum levels of IL-6 and TGF-beta in 29 patients with acute stroke (10 with large cortical cerebral infarction, 9 with subcortical small infarction, and 10 with intracerebral hemorrhage). As an index of brain damage. S-100 protein was also measured. Twelve age-matched healthy subjects were tested as a control. RESULTS: S-100 protein was detected in only 11 patients with large infarction or intracerebral hemorrhage. Its level peaked at day 3 in patients with infarction, whereas it peaked within 24 hours in those with intracerebral hemorrhage. The level of IL-6 was most markedly elevated at day 1, which tended to decrease thereafter. However, its level remained significantly elevated compared with that of the control group even at day 7. The level of TGF-beta was significantly decreased at day 1 and day 3 and tended to return toward the control value thereafter. The levels of both cytokines were not significantly different among the three different stroke subtypes and were not correlated with the number of blood leukocytes and platelets. CONCLUSIONS: The alteration of IL-6 and TGF-beta levels, which occurs rapidly after acute stroke regardless of the subtype, may reflect the changing immunological-inflammatory status of these patients and does not appear to reflect merely the consequence of the brain damage.

Acute Disease↗
PubMed1995

The antitumor activity of doxorubicin against drug-resistant murine carcinoma is enhanced by oral administration of a synthetic staurosporine analogue, CGP 41251.

We evaluated the therapeutic efficacy against murine drug-sensitive and drug-resistant tumor of a combination chemotherapy regimen comprising intravenous administration of doxorubicin (DXR) plus oral administration of the staurosporine analogue CGP 41251 (benzoylstaurosporine), a highly specific inhibitor of protein kinase C (PKC). In vitro studies indicated that the simultaneous presence of noncytotoxic concentrations of CGP 41251 with DXR decreased the median inhibitory concentration (IC50) about 3-fold in the drug-sensitive parental murine cell lines, CT-26P and UV2237. Similar treatment of drug-resistant variants of these tumor cell lines reversed their multiple drug resistant (MDR) phenotype (about a 5-fold increase in their sensitivity to DXR) and increased the cellular accumulation of DXR. Combination therapy in vivo with DXR and CGP 41251 significantly inhibited the SC growth of the drug-resistant CT-26R500 cell line. This effect was confirmed by the ability of this combination therapy to reduce the number of lung metastases produced by IV injection of either the drug-sensitive parental line CT-26P or the drug-resistant subline, CT-26R500. PKC activity was reduced in tumors derived from mice treated with either DXR or CGP 41251, but not from those derived from mice treated with the combination. These results reflect one of the infrequent examples of being able to modulate the sensitivity of in vivo-grown tumors to the antitumor effects of an MDR-related drug and suggest a basis for evaluation of CGP 41251 in clinical trials.

Administration, Oral↗
PubMed1994

Combined radiotherapeutic and surgical management of a spinal cord compression by extramedullary hematopoiesis in a patient with hemoglobin E beta-thalassemia.

A 22-year-old male with a history of hemoglobin E beta zero-thalassemia presented with thoracic spinal cord compression due to extramedullary hematopoietic tissue in the epidural space. Following decompressive laminectomy, this epidural mass was irradiated to 20.4 Gy in 12 fractions. The patient made a complete recovery from his neurological symptoms following treatment. Follow-up radiographs showed significant reductions in size of the extradural tumor. Results from this case supported by review of the literature suggest that radiation therapy, with or without decompressive surgery, is an effective therapy in treatment of patients with spinal cord compression due to epidural extramedullary hematopoietic tissue.

Adult↗
PubMed1993

[Seasonal distribution of chigger mites in the Kanghwa Island and Yongjong Island].

Seasonal distribution of chigger mites in the Kangwha Island and Yongjong Island was studied during the period of October 1992-August 1993. From 42 field rodents collected, 1,290 chiggers were obtained and 8 species of 4 genera were identified. In the Kanghwa Island, Leptotrombidium pallidum was the predominant species through all seasons with the percentage of 93.0%. Whereas, in the Yongjong Island, L. palpale was the predominant species with the percentage of 38.4% and L. pallidum was not found.

Animals↗
PubMed1991

ZOOM: a generic personal computer-based teaching program for public health and its application in schistosomiasis control.

Schistosomiasis, a group of parasitic diseases caused by Schistosoma parasites, is associated with water resources development and affects more than 200 million people in 76 countries. Depending on the species of parasite involved, disease of the liver, spleen, gastrointestinal or urinary tract, or kidneys may result. A computer-assisted teaching package has been developed by WHO for use in the training of public health workers involved in schistosomiasis control. The package consists of the software, ZOOM, and a schistosomiasis information file, Dr Schisto, and uses hypermedia technology to link pictures and text. ZOOM runs on the IBM-PC and IBM-compatible computers, is user-friendly, requires a minimal hardware configuration, and can interact with the user in English, French, Spanish or Portuguese. The information files for ZOOM can be created or modified by the instructor using a word processor, and thus can be designed to suit the need of students. No programming knowledge is required to create the stacks.

Computer-Assisted Instruction↗
PubMed1991

Global schistosomiasis database: practical considerations in the design of a user-friendly database.

A computerized database for monitoring global schistosomiasis data is discussed. The potential target users include schistosomiasis program managers, Ministries of Health of endemic countries, consultants, and WHO Regional Offices. The concept behind the design of the database structure, the user interface and the query interface is addressed along with a brief description of the hardware and software used. The database, holding information on 76 schistosomiasis endemic countries around the world, has been tested in the WHO Regional Offices with positive results.

Databases, Factual↗
PubMed1990

Metrifonate in the control of urinary schistosomiasis in Zanzibar.

Selective population chemotherapy using three doses of metrifonate (7.5 mg/kg body weight each time) at two-week intervals was assessed in an entire community in Kinyasini district in Zanzibar, United Republic of Tanzania. The objectives of the study were to (1) reduce the prevalence of heavy infections (defined as greater than or equal to 50 S. haematobium eggs per 10 ml of urine) by 75% in two years, and (2) reduce the overall prevalence of infection by 50% in two years. A total of 4113 people were examined at least once during the two-year period. In the initial survey the highest proportion of infected individuals was in the 10-14-year age group, and in all subsequent surveys in the 5-9-year age group. The age group with the highest proportion of heavily infected individuals was 5-9 years for all surveys. The overall reduction of prevalence of infection from survey 1 to survey 4 was 52.9% and the prevalence of heavy infection was reduced by 62.2%. The conversion rates (negative to positive in two consecutive surveys) were highest in the longest interval of 12 months and the rates of reversion (positive to negative in two consecutive surveys, without a history of treatment) were highest in the shortest interval of 4 months. Some statistically significant relationships were observed between the number of doses and the egg reduction rates. However, for the egg-negative rates, no statistically significant relationship was observed. In the 4-month interval a 67.6% egg-negative rate was observed among those who took at least one dose; with the 12-month interval a 48.3% egg-negative rate was observed. Thus, selective population chemotherapy with metrifonate was shown to reduce the prevalence and intensity of infection due to S. haematobium over a 24-month period.

Adolescent↗
PubMed1987

A case of leukemia-associated arthritis--identification of leukemic cells in synovial fluid by light microscopy.

One case of arthritis complicating leukemia is described in which leukemic cells were identified in synovial fluid by light microscopy. Although arthritis is a well-known manifestation of leukemia with an incidence of 13.5%, the pathogenesis often is unclear, and the direct demonstration of leukemic cells in synovial fluid has been very uncommon. A 16 year-old male patient was admitted due to left elbow joint pain and swelling. Synovial fluid examination revealed blast cells and this finding has directed to a final diagnosis of acute lymphoblastic leukemia.

Adolescent↗
PubMedDate not supplied

In vitro establishment of cis-diammine-dichloroplatinum(II) resistant lung cancer cell line and modulation of apoptotic gene expression as a mechanism of resistant phenotype.

After exposure of H460 cells to an increasing concentrations of cis-diammine-dichloroplatinum(II) (cisplatin, CDDP) for 6 months, cisplatin resistant cells were isolated (H460/CIS). The biologic behaviors of H460 and H460/CIS cells were tested using animal experiments. Only the resistant cells developed lung metastases despite cisplatin treatment. The characteristics of H460/CIS cells are as follows, MTT analyses revealed that H460/CIS cells were markedly resistant to cisplatin compared with their parental cells. Also, H460/CIS cells exhibited cross-resistance to DNA damaging agents such as doxorubicin (DXR) and etoposide. Cisplatin treatment dramatically increased p53 expression in parental cells but not in H460/CIS cells which expressed basal levels of p53. Without cisplatin treatment, Bcl-2 and Bax were expressed in H460/CIS cells, but not in parental cell. Our data suggested that p53, Bax and Bcl-2 were up-regulated in H460/CIS cells. These changes could explain some of the mechanisms of cisplatin resistance. Thus, H460/CIS could be useful to investigate the mechanisms of drug resistance to cisplatin including apoptotic gene expressions conferring drug resistance, thereby making progress in the treatment of cisplatin-resistant tumor cells.

Animals↗
PubMedDate not supplied

Multidisciplinary management of metastatic colorectal cancer.

When colorectal cancer metastasizes to distant organs, usually multiple sites are involved and treatment consists primarily of systemic chemotherapy and supportive care. Chemotherapeutic agents effective against metastatic colorectal cancer include 5-fluorouracil, often used in combination with leucovorin or methotrexate, and irinotecan (CPT-11). Median survival with optimal chemotherapy regimens ranges from 10 to 15 months. Less frequently, colorectal cancer metastasizes only to the liver or lung. In a minority of these cases, surgical resection can be performed and results in a median survival of 28-46 months for hepatic resections and 24-25 months for pulmonary resections. Five-year survival rates range from 24 to 38% and 21 to 44% for hepatic and pulmonary resections, respectively. For isolated liver metastases that are not surgically resectable, other regional therapies that can be considered are hepatic cryosurgery, radiofrequency ablation, and hepatic arterial infusion chemotherapy. Median survival following cryosurgery is between 26 and 30 months, while median survival following radiofrequency ablation has not been established in large series. Hepatic arterial infusion chemotherapy, especially with newer combination drug regimens, may increase survival in patients with isolated liver metastases compared to systemic chemotherapy, but this must be confirmed in randomized, prospective trials. Colorectal cancer metastases to the brain can be treated with radiation therapy or surgical resection, but median survival with treatment is less than one year.

Antineoplastic Agents↗
PubMedDate not supplied

Influence of p53 on herpes simplex virus type 1 vectors for cancer gene therapy.

Herpes simplex virus type 1 (HSV 1) vectors are under investigation for use in gene therapy for colorectal cancer liver metastases. Approximately 60% of colorectal cancers possess p53 mutations, and p53 mutations can cause tumor cell resistance to radiation therapy and chemotherapy. p53 is also known to co-localize with at least one HSV 1 protein and influence HSV 1 gene expression. The purpose of this study was to determine if the loss or mutation of p53 in tumor cells alters the cytotoxicity of HSV 1 vectors. HSV 1 vector-mediated in vitro cytotoxicity assays were performed using stable transfectants of SAOS-2-LM2 cells and WiDr cells that express no p53, wild-type p53, mutant p53, or both wild-type p53 mutant p53. All stable transfectants were equally susceptible to HSV 1 vector cytotoxicity, and cell lines with mutant p53 were not resistant to HSV 1 vectors. These results provide additional rationale for the application of HSV 1 vector gene therapy for colorectal cancer.

Animals↗
PubMedDate not supplied

Limbic system abnormalities associated with mesial temporal sclerosis: a model of chronic cerebral changes due to seizures.

In a landmark 1966 study, widespread cerebral abnormalities were discovered at histopathologic examination of autopsied brains from patients with long-standing temporal lobe epilepsy. In the brains diagnosed with mesial temporal sclerosis (MTS), these abnormalities involved not only the hippocampus but also other structures of the limbic system and medial temporal lobe. Many of these changes are evident at magnetic resonance imaging. Because many of these abnormalities are found within limbic structures along a known neuroanatomic pathway (the Papez circuit), they suggest a pattern of cerebral damage related to the physiologic interconnections between the hippocampus and associated limbic structures. It appears that limbic damage associated with MTS more often affects the structures most closely connected to the hippocampus along the Papez circuit. The frequency and widespread distribution of these cerebral abnormalities suggest that MTS is not limited to the medial temporal lobe but instead represents a limbic system disorder.

Amygdala↗
PubMedDate not supplied

Behavior of murine renal carcinoma cells grown in ectopic or orthotopic sites in syngeneic mice.

We examined whether the organ microenvironment modulates the metastatic behavior and the response to doxorubicin (DXR) in murine renal carcinoma (RENCA) cells. Tumor cells were injected into kidney (orthotopic) and subcutis (ectopic) of syngeneic mice. Lung metastases developed in up to 57% (17/30) of animals having kidney tumors but not in those with skin tumors. Tumors growing in the kidney were more resistant to DXR than tumors growing in the subcutis when mice were given intravenous injections of DXR (8 mg/kg) on days 8 and 15 after implantation. In addition, tumor cells cultured from kidney tumors were initially more resistant to DXR than tumor cells cultured from subcutis tumors. After tumor cells were passaged in vitro, all cells exhibited a similar sensitivity to DXR. Additionally, we examined the expression levels of mdr1, EGFR and type IV collagenase by an in situ mRNA hybridization technique. A higher mRNA expression for type IV collagenase and EGFR was found in kidney tumors than in subcutis tumors. These results demonstrate that the organ environment influences the drug responsiveness and the expression of metastasis-related genes in murine renal carcinoma cells.

Animals↗
PubMedDate not supplied

Tumor site-dependent differential modulation of systemic immunity in RENCA bearing mice.

Renal cell carcinoma (RCC) is a highly metastatic cancer which is known to be immunogenic and responsive to immunotherapies using cytokines. The effect of tumor site (organ microenvironment) on the biologic behavior of murine RCC cell line (RENCA) was examined by observing systemic immunomodulations. Reduction of the spleen size observed in tumor bearing mice correlated with a significant decrease in splenic nucleated cell numbers. In the mice bearing RENCA cell tumors in the renal subcapsule, a significant increase of splenic T cell blastogenesis against Con-A (234% of naive control) was observed with reduction of NK activity (45% of naive control). The changes in T cell blastogenesis and NK activity observed in subcutis (s.c.) inoculated RENCA tumor bearers were less significant. However, macrophage functioning and proportions in the spleen were significantly increased only in s.c. tumor bearers. Data indicated tumor site-dependent differential modulation of systemic immunity in RENCA bearing mice which suggests that immunotherapy for RCC should consider not only the tumor but also the tumor's microenvironment.

Animals↗