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Biomedical subjects

K W Choi

Publications and source records attributed to K W Choi.

At least 55 records · Page 3Linked to original sources
PubMed1997

Preoperative evaluation of the curative resectability of gastric cancer by abdominal computed tomography and ultrasonography: a prospective comparison study.

OBJECTIVES: We compared the ability of preoperative abdominal computed tomography (CT) with that of preoperative abdominal ultrasonography (US) in predicting the extent of tumor growth and the curative resectability of gastric cancer. METHODS: Abdominal CT and US were done in 95 patients with gastric adeno-carcinoma. The radiologic findings were prospectively compared with surgical and pathologic findings. RESULTS: The sensitivities of abdominal CT and US in detecting the perigastric lymph node involvement were 26.6% and 20%, respectively. The sensitivity of abdominal CT in predicting the pancreatic invasion (60%) was better than that of abdominal US (20%). However, there were 6 false positive diagnosis of pancreatic invasion by abdominal CT; in contrast, there was no false positive diagnosis of pancreatic invasion by abdominal US. Of 95 patients who underwent surgical exploration, 14 were found to have unresectable tumors because of extragastric organ involvement and distant metastases. Abdominal CT falsely predicted 8 of 14 cases in which curative gastric resection was impossible as resectable. Moreover, abdominal CT falsely predicted 5 of 81 cases in which curative gastric resection was possible as unresectable. Abdominal US falsely predicted 12 of 14 cases in which curative surgery was impossible as resectable. CONCLUSION: Preoperative abdominal Ct and US did not accurately predict the tumor extent and the curative resectability of the gastric cancer. Especially, abdominal CT finding of pancreatic invasion by gastric cancer should not be a contraindication for surgical exploration.

Abdomen↗
PubMed1997

A case of intraductal papillary tumor of pancreas associated with mucinous ductal ectasia.

Intraductal papillary neoplasm associated with mucinous ductal ectasia is an uncommon cystic disease of the pancreas. This tumor is characterized by the multilocular cyst lined by mucin producing cells with variable degrees of atypia and ductal ectasia. In addition, this tumor has a favorable prognosis in contrast to other mucinous cystic tumor of the pancreas. Reports on intraductal mucin producing tumor are quite limited and most of them are found in Japanese literature. We report a case of intraductal papillary adenocarcinoma with marked dilatation of the pancreatic duct filled with mucin in a 72-year-old female patient.

Adenocarcinoma, Mucinous↗
PubMed1996

Independent determination of symmetry and polarity in the Drosophila eye.

In each facet of the Drosophila compound eye, a cluster of photoreceptor cells assumes an asymmetric trapezoidal pattern. These clusters have opposite orientations above and below an equator, showing global dorsoventral mirror symmetry. However, in the mutant spiny legs, the polarization of each cluster appears to be random, so that no equator is evident. The apparent lack of an equator suggests that spiny legs+ may be involved in the establishment of global dorsoventral identity that might be essential for proper polarization of the photoreceptor clusters. Alternatively, a global dorsoventral pattern could be present, but spiny legs+ may be required for local polarization of individual clusters. Using an enhancer trap strain in which white+ gene expression is restricted to the dorsal field, we show that white+ expression in spiny legs correctly respects dorsoventral position even in facets with inappropriate polarizations; the dorsoventral boundary is indeed present, whereas the mechanism for polarization is perturbed. It is suggested that the boundary is established before the action of spiny legs+ by an independent mechanism.

Animals↗
PubMed1996

Performance characteristics of recombinant enzyme immunoassay to detect antibodies to human immunodeficiency virus type 1 (HIV-1) and HIV-2 and to measure early antibody responses in seroconverting patients.

We investigated the performance of a double-antigen sandwich recombinant enzyme immunoassay (EIA; Abbott Laboratories, North Chicago, Ill.) and compared it with that of a synthetic-peptide-based EIA (Biochem Immunosystems, Montreal, Quebec, Canada) for the detection of human immunodeficiency type 1 (HIV-1) and HIV-2 antibodies in 2,321 clinical serum samples. The results of both EIA methods and Western blot (immunoblot) were in agreement for 1,046 HIV-1 and 10 HIV-2 specimens from a panel of known positives. From a prospective panel of 1,085 specimens, 38 proved to be positive by both EIAs and Western blot, 3 were positive by the recombinant EIA only, and 9 were positive by the peptide EIA only, for calculated specificities of 99.71 and 99.04%, respectively. Of 180 specimens from a seroconversion panel collected from 77 patients, the results for 170 were in agreement by all antibody testing methods and 10 were found to be repeat reactive for HIV antibodies by the recombinant EIA only. All 10 were initial specimens of seroconverting patients; 7 were also reactive for HIV p24 antigen. An examination of four of these sera by radioimmunoprecipitation assay showed gp120 and gp160 bands in each. Analysis of the anti-Env antibody class in three of these samples showed that one consisted of immunoglobulin M (IgM) only and two contained both IgG and IgM antibodies. Although both EIA procedures were sensitive and specific in the detection of antibodies to HIV-1 and HIV-2 and both were capable of detecting early antibodies, the recombinant assay was more sensitive for antibody detection during early seroconversion.

Evaluation Studies as Topic↗
PubMed1995

Early decisions in Drosophila eye morphogenesis.

Recent analyses have shed light on the roles of genes involved in early events of eye cell determination and the spatiotemporal control of differentiation within the eye field. These genes function at sequential steps in the programming, initiation, or progression of differentiation, highlighting an elegant orchestration of gene activities to achieve this striking developmental event. Progress has been made in the study of the coordination between cell cycle control and cell differentiation, as well as in the genetic control of morphogenetic movements within the developing eye disc.

Animals↗
PubMed1995

High incidence of resistance to multiple antimicrobials in clinical isolates of Streptococcus pneumoniae from a university hospital in Korea.

One hundred thirty-one strains of Streptococcus pneumoniae isolated from clinical specimens between January 1991 and April 1993 were serotyped and tested for susceptibility to 10 antimicrobials by the agar dilution method. Five serotypes (6A, 6B, 14, 19F, and 23F) accounted for 67% of all isolates. Seventy percent of isolates were not susceptible to penicillin, exhibiting either intermediate resistance (37%) or high-level resistance (33%); 82% of isolates from children and 59% of those from normally sterile body fluids were resistant to penicillin. A significantly increased rate of penicillin resistance (P < .01, Fisher's exact or chi 2 test) was associated with hospitalization, an age of < or = 15 years, ongoing antimicrobial therapy at the time of isolation of the organism, nosocomial acquisition, and several specific serotypes (6, 14, 19F, and 23F). No penicillin-resistant strain showed beta-lactamase activity. Various proportions of the penicillin-resistant strains also displayed resistance to cefaclor (89%), cefotaxime (82%), chloramphenicol (65%), erythromycin (52%), and ciprofloxacin (15%), but none was resistant to teicoplanin or vancomycin. The prevalence of pneumococcal resistance documented in Korea in this study is among the highest figures published to date.

Adolescent↗
PubMed1995

Evaluation of bone metastases by Tc-99m MDP imaging in patients with stomach cancer.

The authors conducted a retrospective review of 234 bone scans of stomach cancer patients who had been diagnosed at the Seoul National University Hospital. In 106 of the 234 cases (45.3%), there were abnormal bone scan results, suggestive of bone metastases. The most common site of bone metastases was the spine, followed by the ribs, pelvis, femur, and skull. These sites were similar to those known for other malignant diseases. The incidence of bone metastases increased according to the duration of disease, especially within 12 months after diagnosis in patients with stage III gastric cancer. The incidence of bone metastases increased as the clinical stage increased. However, the incidence of metastases did not relate to gastric cancer pathologic type. The authors found 6 cases of "superscan" in the 234 bone scans (2.6%). The bone scan findings correlated positively with the level of serum alkaline phosphatase.

Bone Neoplasms↗
PubMed1994

Rotation of photoreceptor clusters in the developing Drosophila eye requires the nemo gene.

The Drosophila eye consists of a reiterative hexagonal array of photoreceptor cell clusters, the ommatidia. During normal morphogenesis, the clusters in the dorsal or ventral halves of the disc rotate 90 degrees in opposite directions, forming mirror images across a dorsoventral equator. In the mutant nemo (nmo), there is an initial turning of approximately 45 degrees, but further rotation is blocked. Genetic mosaic analysis indicates that the nmo gene acts upon each cluster as a whole; normal nmo function in one or more photoreceptor cells appears to be sufficient to induce full rotation. The nmo gene sequence encodes a serine/threonine protein kinase homolog, suggesting that the kinase is required to initiate the second step of rotation. In another mutant, roulette, excessive rotation through varying angles occurs in many ommatidia. This defect is suppressed by nmo, indicating that nmo acts upstream in a rotation-regulating pathway.

Amino Acid Sequence↗
PubMed1994

Migration of glia along photoreceptor axons in the developing Drosophila eye.

We have identified a set of retinal basal glia, designated RBG cells, in the axon layer of the developing Drosophila eye disc. In vivo pulse labeling with bromodeoxyuridine shows that these cells originate in the optic stalk and migrate into the disc. In mutants lacking photoreceptor axons, RBG cells accumulate in the optic stalk, but do not invade the disc. The association of RBG cells with photoreceptor axons, their origin in the optic stalk, and their migration into the retina are in common with the behavior of astrocytes in the developing mammalian retina.

Animals↗
PubMed1993

Radioimmunoscintigraphy of advanced gastrointestinal carcinomas employing I-131 labeled CEA-79 monoclonal antibody.

CEA-79 is a murine IgG2a type monoclonal antibody (MoAb) generated using purified CEA from culture supernatants of a human colon cancer cell line, LS174T. The association constant and immunoreactivity of the I-131 labeled CEA-79 ranged from 2.0 to 3.2 x 10(9) l/mole, and from 54 to 74%, respectively. The purpose of this study was to evaluate the feasibility of radioimmunoscintigraphy employing MoAb CEA-79 in patients with advanced gastrointestinal carcinomas. Two mgs of MoAb CEA-79 was labeled with 111 MBq (3 mCi) of I-131, and infused intravenously in 6 stomach cancer and 16 colon cancer patients. Out of 6 patients with stomach cancer, immunoscintigraphy was able to detect the tumors in 4 cases. However, immunoscintigraphy found out tumors in all patients with colon cancer. Moreover, 1 patient with stomach cancer and 2 patients with colon cancer showed increased uptake of MoAb in the tumor lesions despite normal serum levels of CEA. We could conclude that this antibody has a potential as a new imaging agent for the diagnosis of gastrointestinal carcinoma.

Adult↗
PubMed1992

Risk of gastric cancer among Korean familial adenomatous polyposis patients. Report of three cases.

Gastric cancer has been recognized as an extracolonic manifestation in patients with familial adenomatous polyposis (FAP). In Korea, gastric cancer is the most common malignant neoplasm. In a recent survey, we collected data from 72 Korean patients with FAP. Among them, three (4.2 percent) were found to have associated gastric cancer. This incidence of gastric cancer in our series is much higher than the previous reports from Japan and other countries. The expected cumulative incidence of gastric cancer among these 72 patients was 0.44, which gives the standardized incidence ratio of 6.9 (95 percent CI, 1.4-20.1). This difference in incidence of gastric cancer was statistically significant (P less than 0.05), which implies that patients with FAP are at significantly higher risk of developing gastric cancer compared with the general population in Korea. These findings confirm an increased risk of gastric cancer in FAP patients, even in a region where gastric cancer is highly prevalent.

Adenomatous Polyposis Coli↗
PubMed1991

Deficient protein kinase C activity in turnip, a Drosophila learning mutant.

The Drosophila mutant turnip was initially isolated based on poor learning performance (Quinn, W.G., Sziber, P.P., and Booker, R. (1979) Nature 277, 212-214). Here we show that turnip is dramatically reduced in protein kinase C (PKC) activity. In addition, turnip flies are deficient in phosphorylation of a 76-kDa head membrane protein (hereafter pp76) which is a major substrate for protein kinase C in homogenates of wild-type flies. Reduced PKC activity, defective pp76 phosphorylation, and most of turnip's learning deficiency co-map genetically to a region on the X-chromosome, 18A5-18D1-2, spanned by the deletion Df(1)JA27. Apparently turnip+ is not a structural gene for PKC because Drosophila PKC genes map elsewhere in the genome. Our results suggest that turnip gene product is required for activation of PKC and that PKC plays a role in associative learning in Drosophila.

Animals↗
PubMed1991

Atypical clinical manifestations of amebic colitis.

Amebic colitis is a disease revealing diverse clinical manifestations and endoscopic gross features and often confused with other types of colitis. In case of misdiagnosis as an idiopathic inflammatory bowel disease or delayed recognition of intestinal amebiasis, an undesirable outcome may occur resulting from erroneous administration of steroids or delayed antiamebic treatment. To demonstrate the pitfalls in the diagnosis and treatment of intestinal amebiasis, 3 cases of amebic colitis with atypical clinical manifestations are presented in this paper. In conclusion, despite the low sensitivities of routine stool examination for parasite and histopathologic confirmation in biopsy specimen, every effort must be made to find amebic trophozoites either in fresh stool or biopsy specimens for prompt and correct diagnosis of amebic colitis when we manage patients with chronic intestinal ulcerations, even though their clinical course and endoscopic findings are not typical of amebiasis. Moreover, following initial successful anti-amebic therapy, more careful clinical, endoscopical, and parasitological follow-up should be done for the early detection of recurrence.

Adult↗
PubMed1991

Temporal changes in the clinical type or diagnosis of Behçet's colitis in patients with aphthoid or punched-out colonic ulcerations.

The intestinal lesion of Behçet's colitis shows aphthoid or punched-out ulceration. However, the diagnosis of Behçet's colitis should be based on the presence of other stigmata of Behçet's syndrome, since these morphological characteristics are not pathognomonic by themselves. Furthermore, the stigmata of Behçet's syndrome could appear simultaneously or separately with intervals of several months to years. Besides, when a physician first meets patients with intestinal ulcerations of aphthoid or punched-out shape, if they do not have any stigma of Behçet's syndrome, the physician has some difficulty in making a diagnosis of Behçet's colitis. The purpose of this retrospective study was to investigate the followings: 1) The upgrade in clinical type of Behçet's colitis with the advance of time. 2) What portion of the patients with aphthoid or punched-out ulcerations, but without any other clinical feature of Behçet's syndrome, could be diagnosed as Behçet's colitis with the advance of time? During the mean follow-up period of 38.2 months, 4 (22.2%) out of 18 patients with Behçet's colitis upgraded their clinical types. In the nonspecific ileocolitis group, who had no major stigma of Behçet's syndrome on their initial visit, 3 (30%) out of 10 patients were subsequently diagnosed as Behçet's colitis during the mean follow-up period of 33.3 months. From these results, we could conclude that in possible or suspicious cases of Behçet's colitis, a more confident diagnosis could be made by close observations for new developments of major stigma of Behçet's syndrome. Even in cases of nonspecific ileocolitis, the diagnosis of Behçet's colitis could be made in a significant number of cases as time goes by.

Adolescent↗
PubMed1990

Polymorphic reticulosis with colonic lesion--a case report.

A 38-year-old man was admitted with a high fever, sore throat, and right upper quadrant pain. Nine months before his admission, he had undergone right hemicolectomy under the impression of intestinal lymphoma. But there had been no evidence of lymphoma on microscopic examination. Under the postoperative diagnosis of inflammatory bowel disease, corticosteroid therapy was tried without response. On the follow-up colonoscopic examination, an ovoid ulcer, with convergence of the surrounding mucosal folds at the descending colon and an irregularly shaped ulcer at the ileocolic anastomotic site, were found. The colonoscopic diagnosis was Behcet's colitis. After pathologic slides of biopsy and surgical specimens obtained from the palatine tonsil and colon were reviewed, the diagnosis of polymorphic reticulosis was made. The patient received anticancer chemotherapy, including cyclophophamide and glucocorticosteroid. To date, colonic involvement of polymorphic reticulosis has not been reported. Because of the similarity of the colonoscopic findings to those of Behcet's colitis, polymorphic reticulosis should be included in the differential diagnosis of inflammatory bowel disease. We assume that this is the first case of polymorphic reticulosis involving the colon with characteristic colonoscopic findings.

Adult↗
PubMed1989

Evaluation of omeprazole as a treatment for gastric and prepyloric ulcer in Korean patients.

The healing efficacy of omeprazole was assessed in 57 Korean patients with endoscopically-proven gastric (GU) and/or prepyloric (PPU) ulcers of at least 5 mm diameter. Fifty-three patients presented with GU, two with PPU and two with both types of ulcer. The maximum ulcer diameter was 5-10 mm in 27 patients and greater than 10 mm in 30 patients. All patients received 20 mg of omeprazole each morning for 4-8 weeks depending on ulcer healing. Ulcer healing rates were comparable using both 'intention to treat' (IT) and 'per protocol' (PP) analyses. Following the IT approach 82% (47 of 57) of patients were healed at 4 weeks and 98% (56 of 57) at 8 weeks. Following the PP approach, the corresponding healing rates were 83% (44 of 53) and 98% (55 of 56), respectively. Smoking was found to have a significant effect on ulcer healing at 4 weeks (P = 0.03), with 96% (26 of 27) of non/occasional smokers healed versus only 69% (18 of 26) of daily/heavy smokers. Ulcer size did not have a significant effect on healing, however. Ulcer symptoms, reported by all patients at entry, disappeared rapidly after commencement of omeprazole therapy. Only four patients reported mild symptoms at 4 weeks and no symptoms were reported at 8 weeks. No clinically significant changes in haematology or clinical chemistry (other than a rise in leucocytes in one patient) and no serious adverse events were observed. In conclusion, omeprazole 20 mg each morning was found to be safe and highly effective for treatment of gastric and prepyloric ulcer in Korean patients, producing a 98% healing rate. Symptom relief was rapid and the drug was well tolerated.

Adult↗
PubMed1988

Influence of dietary fat, caloric restriction, and voluntary exercise on N-nitrosomethylurea-induced mammary tumorigenesis in rats.

The effect of dietary fat, energy restriction, and exercise on N-nitrosomethylurea (NMU:CAS:684-93-5)-induced mammary tumorigenesis in female F344 rats was investigated. Rats were fed the NIH-07 diet until N-nitrosomethylurea administration on Day 50 of age, when they were transferred to six treatment groups. Three sedentary groups were fed either high-fat (20%, w/w), medium-fat (10%), or low-fat (5%) diets ad libitum (HFAL, MFAL, LFAL, respectively); two sedentary groups were fed high fat and medium fat diets restricted to 75% of the food consumed by their ad libitum counterparts (HFR, MFR), and one group was fed a HFAL diet but allowed free access to an activity wheel (HFEX). Tumor yields among the three ad libitum sedentary groups were significantly greater in the HFAL and MFAL groups when compared to the LFAL group. Dietary restriction reduced tumor yields by more than 90% of ad libitum controls regardless of fat intake. Voluntary exercise reduced tumor yields and delayed time of tumor appearance in HFEX animals to levels similar to those found in LFAL animals. Animals with voluntary access to exercise wheels averaged between 1.03 and 2.85 miles/day, consumed more food (+18%), and exhibited greater weight gain (+13%) than their sedentary counterparts. Restricted animals exhibited significantly decreased body weight gains (-15%) compared to their ad libitum counterparts, but no differences in weight gains were detected among the HFAL, MFAL, and LFAL groups, despite widely varying amounts of fat intake. Body composition studies indicated that body fat content was not influenced by the quantity of fat consumed in the diet, but was significantly reduced by caloric restriction (-20 to 26%) and exercise (-20%). While the precise mechanisms underlying the tumor-promoting effects of HFAL diets and the antipromoting effects of energy restriction and exercise remain to be elucidated, available evidence suggests that these effects are not due to alterations in energy homeostasis per se, but may instead be exerted indirectly, and perhaps independently via endocrine, paracrine, or neurohormonal mechanisms.

Animals↗