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Biomedical subjects

Y T Ko

Publications and source records attributed to Y T Ko.

At least 19 recordsLinked to original sources
PubMed2002

Effect of endotoxin on expression of TNF receptors and transport of TNF-alpha at the blood-brain barrier of the rat.

The transport mechanism mediating brain uptake of tumor necrosis factor (TNF)-alpha has been studied. When (125)I-labeled rat TNF-alpha was used in internal carotid artery perfusions in rats, the cytokine showed transcytosis through the blood-brain barrier in intact form (permeability-surface area product 0.34 +/- 0.13 microl. min(-1). g(-1)). Uptake was inhibited by low nanomolar concentrations of unlabeled rat TNF-alpha. Human TNF-alpha, which does not interact with the p80 TNF receptor in rodents, showed no brain uptake. mRNA expression of both p60 and p80 receptors could be demonstrated in native brain microvessel preparations. These transcripts increased to 149% (p60) and 127% (p80) of control 4 h after a systemic immune stimulation (2 mg/kg bacterial endotoxin ip). Lipopolysaccharide treatment did not alter the rate of brain uptake of TNF-alpha measured between 4 and 24 h later. In conclusion, a receptor-mediated mechanism is responsible for the transcytosis of TNF-alpha. Saturable transport, requiring the p80 receptor, occurs at concentrations encountered under pathophysiological conditions and therefore constitutes a relevant mechanism of communication between the immune system and the brain.

Animals↗
PubMed2001

Radiologic anatomy of the rabbit liver on hepatic venography, arteriography, portography, and cholangiography.

UNLABELLED: Seo TS, Oh JH, Lee DH, et al. Radiologic anatomy of the rabbit liver on hepatic venography, arteriography, portography, and cholangiography. Invest Radiol 2001;36:186-192. RATIONALE AND OBJECTIVES: The radiologic anatomy of rabbit liver has received little study but is important in many experimental investigations. METHODS: Twenty-four rabbits were studied by using hepatic venograms, aortograms, hepatic arteriograms, cholangiograms, and portograms. RESULTS: In all cases, the right, middle, and left hepatic veins drained into the inferior vena cava just below the diaphragm, and the caudate lobe hepatic vein drained more inferiorly. The proper hepatic artery was a branch of the common hepatic artery in 96%. The first branch of the proper hepatic artery was the caudate lobe artery. The remaining main hepatic artery was divided into the right and left hepatic arteries. The left hepatic artery was further divided into the medial and lateral segmental branches in 95%. The anatomy of the portal vein or bile duct was the same as the hepatic artery in 100% of cases. CONCLUSIONS: Knowledge of the normal patterns and variations of the vessels and bile duct will be helpful for experiments of the rabbit liver in future studies.

Animals↗
PubMed2001

Sonographic findings of solid and papillary epithelial neoplasm of the pancreas.

OBJECTIVE: To evaluate the sonographic findings of solid and papillary epithelial neoplasm of the pancreas, a rare tumor occurring in young women. METHODS: The sonographic findings of 11 cases of pathologically proven solid and papillary epithelial neoplasm of the pancreas were retrospectively evaluated. RESULTS: In 6 cases (55%), combined cystic and solid portions of the masses were observed, whereas only solid-looking masses without anechoic cystic portions were seen in 4 cases (36%). One case (9%) had marginal calcification, consequently, the internal architecture was not evaluated by sonography. Internal echoes were seen in 3 of 6 cystic and solid masses. Septa were seen in 3 cases. Among 11 cases of solid and papillary epithelial neoplasm, tumor margins were well defined in 10, and tumor capsules were detected in 9 (echogenic in 7 and hypoechoic in 2). Calcifications were seen in 3 cases (27%). CONCLUSIONS: The characteristic sonographic findings of solid and papillary epithelial neoplasm were well-encapsulated, cystic, and solid masses, but sometimes the mass was seen as a pure solid-looking mass or had internal septations or calcifications.

Adult↗
PubMed2000

Survival of Pseudomonas fluorescens and Salmonella typhimurium after electron beam and gamma irradiation of refrigerated beef.

The radurization effects of gamma ray and electron beam irradiation at 1.5 and 3.0 kGy on beef steaks inoculated with Salmonella Typhimurium and Pseudomonas fluorescens were investigated during 8 days of storage at 5 degrees C. Total bacterial counts and numbers of Salmonella Typhimurium and P. fluorescens were analyzed at 2-day intervals. Total bacterial counts of samples irradiated by both gamma rays and electron beam were significantly (P < 0.05) reduced by 3.8 to 5.3 log CFU/g. Salmonella Typhimurium was not detectable during the experimental period. P. fluorescens counts of beef samples irradiated by gamma rays at both 1.5 and 3.0 kGy were not detected; however, P. fluorescens in samples irradiated by electron beam at 1.5 and 3.0 kGy was recovered after 2 days, and bacterial counts reached 7.8 and 6.9 log CFU/g, respectively. Both gamma ray and electron beam irradiation reduced total bacterial counts initially, possibly extending shelf life. Irradiation was very effective in destroying Salmonella Typhimurium; however, P. fluorescens was not completely eliminated by electron beam irradiation. Consequently, gamma ray irradiation was more effective than electron beam irradiation in the destruction of P. fluorescens.

Animals↗
PubMed2000

Treatment of prostatic abscess: value of transrectal ultrasonographically guided needle aspiration.

The purpose of this study was to assess the effectiveness of transrectal ultrasonographically guided needle aspiration in the treatment of prostatic abscess. Fourteen patients with prostatic abscess were evaluated with this technique and treated with sonographically guided needle aspiration. Using this technique, all cases (100%) had one or more hypoechoic areas within the prostate that contained inhomogeneous materials; in 10 patients (71.0%), the lesion showed internal septa or solid portion. The margins of the hypoechoic area were well defined and thick in 11 patients (79.0%) and poorly defined in 3 patients (21.0%). The estimated volume of the prostatic abscess ranged between 2 and 28 ml (mean, 12.0 ml). The presence of a pus collection within the prostate was confirmed by transrectal ultrasonographically guided aspiration in all patients. However, successful treatment of prostatic abscess with transrectal needle aspiration was done in 12 (86.0%) of 14 patients; the treatment failed in 2 (14.0%) of 14 patients. One patient was treated with perineal incision and drainage and the other with transurethral resection. The amount of pus drained ranged between 1 and 39 ml (mean, 12.0 ml). On follow-up transrectal ultrasonographic examination, no remaining abscess pocket was found within the prostate in any of the cases. One year later, the prostatic abscess recurred in one case. In conclusion, transrectal ultrasonographic guidance is useful in the diagnosis of prostatic abscess as well as in the guidance for aspiration and the drainage of such abscesses. Transrectal ultrasonographically guided needle aspiration could be an effective method for treating prostatic abscess.

Abscess↗
PubMed1999

Potentiation of hydrogen peroxide, nitric oxide, and cytokine production in RAW 264.7 macrophage cells exposed to human and commercial isolates of Bifidobacterium.

Bifidobacteria have been previously shown to stimulate immune function and this may be mediated by macrophages. The RAW 264.7 cell line was used here as a macrophage model to assess the effects of human and commercial Bifidobacterium isolates on the production nitric oxide (NO), hydrogen peroxide (H2O2) and the cytokines IL-6 and tumor necrosis factor (TNF)-alpha. Thirty three Bifidobacterium strains differentially stimulated the production of H2O2 NO, TNF-alpha, and IL-6 in a dose-dependent manner in 24-h cultures. In the presence of lipopolysaccharide (LPS) the effects of bifidobacteria on NO and H2O2 were masked and were less pronounced at the later stage of incubation. Co-stimulation of macrophages with both LPS and Bifidobacterium increased the production of IL-6 synergistically. In contrast, LPS reduced the ability of the bifidobacteria-induced macrophages to produce TNF-alpha. Our results demonstrated that both human and commercial Bifidobacterium strains can stimulate H2O2, NO, TNF-alpha, and IL-6 production, and this effect was strain-dependent. The in vitro approaches employed here should be useful in further characterization of the effects of bifidobacteria on gastrointestinal and systemic immunity.

Animals↗
PubMed1995

Characterization of the small subunit ribosomal RNA gene of the oyster parasite Haplosporidium costale.

The small subunit ribosomal RNA (SSU rRNA) gene of the oyster parasite Haplosporidium costale was characterized from spore DNA by polymerase chain reaction (PCR) and molecular cloning. Sequence analysis showed that identical clones were obtained from separate batches of spore samples. The gene is 1791 nucleotides in size. It has 84.5% sequence similarity to that of a related oyster parasite, Haplosporidium nelsoni, 71.8% similarity to that of its oyster host, Crassostrea virginica, and 75.4% similarity to that of another oyster parasite, Perkinsus marinus. Among the variable regions of these SSU rRNA genes, H. costale-specific primers were designed and used to confirm parasite identity by the PCR technique. A common 150 base pair amplification product was obtained from DNA samples of H. costale spore DNA, DNA prepared from tissue sections of oysters infected with H. costale plasmodia, and the H. costale SSU rRNA clone. There was no detectable product from DNA samples isolated from tissue sections of oysters infected with H. nelsoni plasmodia.

Animals↗
PubMed1994

Inhibition of yeast (1,3)-beta-glucan synthase by phospholipase A2 and its reaction products.

Fungal (1,3)-beta-glucan synthases are sensitive to a wide range of lipophilic inhibitors and it has been proposed that enzyme activity is highly sensitive to perturbations of the membrane environment. Yeast membranes were exposed to phospholipases and various lipophilic compounds, and the resultant effects on glucan synthase activity were ascertained. Glucan synthase from Saccharomyces cerevisiae was rapidly inactivated by phospholipase A2 (PLA2), and to a lesser extent by phospholipase C. Inactivation was time and dose-dependent and was protected against by EDTA and fatty-acid binding proteins (bovine and human serum albumins). Albumins also partially protected against inhibition by papulacandin B. PLA2 reaction products were structurally characterized and it was shown that fatty acids and lysophospholipids were the inhibitory moieties, with no novel inhibitory compounds apparent. Glucan synthase was inhibited by a range of fatty acids, monoglycerides and lysophospholipids. Inhibition by fatty acids was non-competitive, and progressive binding of [14C]oleic acid correlated with activity loss. Fluorescence anisotropy studies using diphenylhexatriene (DPH) confirm that fatty acids increase membrane fluidity. These results are consistent with proposals suggesting that glucan synthase inhibition is due in part to non-specific detergent-like disruption of the membrane environment, in addition to direct interactions of lipophilic inhibitors with specific target sites on the enzyme complex.

Aminoglycosides↗
PubMed1994

Use of cilofungin as direct fluorescent probe for monitoring antifungal drug-membrane interaction.

Cilofungin is an antifungal cyclopeptide which inhibits cell wall (1,3)-beta-glucan biosynthesis in fungal organisms, and its action against Candida albicans (1,3)-beta-glucan synthase has been widely studied. Since glucan synthase inactivation is thought to partially result from perturbations of the membrane lipid environment, the interaction of cilofungin with fungal membranes and phosphatidylcholine membrane vesicles was studied. Cilofungin, which contains two independent aromatic groups, has an excitation maximum of 270 nm and an emission maximum of 317 nm in aqueous solution. Comparison of the fluorescence properties of cilofungin with those of the analogs pneumocandin B0, N-acetyl-tyrosinamide, and 4-hydroxybenzamide indicated that the emission of cilofungin largely derived from the p-octyloxybenzamide side chain. Microsomal membranes from Saccharomyces cerevisiae, C. albicans, and phosphatidylcholine membrane vesicles induced a blue shift in the cilofungin emission spectrum and increased the cilofungin steady-state emission anisotropy, providing direct evidence for a cilofungin-membrane interaction. Cilofungin interacted more strongly with membranes of C. albicans than with those of S. cerevisiae, correlating with previous findings that C. albicans is far more susceptible than S. cerevisiae to the action of cilofungin. These findings support the hypothesis that drug-induced inhibition of the (1,3)-beta-glucan synthesis results from the perturbation of the membrane environment and the interaction with the glucan synthase complex combined. The study demonstrated ways in which the fluorescence properties of drugs can be used to directly evaluate drug-membrane interactions and structure-activity relationships.

Anti-Bacterial Agents↗
PubMed1994

Exophytic adenocarcinoma of the stomach: CT findings.

OBJECTIVE: Exophytic adenocarcinomas of the stomach are tumors that have large extraluminal portions. Exophytic growth of gastric carcinoma is rare, and such tumor may be confused with gastric leiomyosarcoma. The purpose of this study was to assess the CT findings of exophytic adenocarcinoma of the stomach and to determine their value in distinguishing between it and gastric leiomyosarcoma. MATERIALS AND METHODS: Twenty patients with exophytic adenocarcinomas of the stomach confirmed by surgery or endoscopic biopsy were included in the study. CT scans were assessed retrospectively for the size, location, and character of the mass and the presence of adjacent thickening of the gastric wall and outlet obstruction. RESULTS: The masses were from 5 to 14 cm in diameter (mean, 9 cm). The mass was in the gastric antrum in 11 cases, the body of the stomach in six cases, the body and antrum in two cases, and the gastric fundus and body in one case. CT showed an exogastric mass with a variable degree of internal low density or necrosis in all 20 cases. Thickening of the gastric wall adjacent to the mass appeared to be a specific finding of exogastric adenocarcinoma (n = 14); it was not seen in reported cases of leiomyosarcoma. Gastric outlet obstruction was seen in four cases, and ulcer was detected in eight cases. The degree of low density or necrosis within the mass was minimal in eight cases, moderate in seven cases, and severe in five cases. CONCLUSION: Our results suggest that CT findings of thickening of the gastric wall adjacent to an exogastric mass, representing spread of cancer to adjacent gastric wall, and/or gastric outlet obstruction are typical of exophytic adenocarcinoma of the stomach and allow distinction between it and gastric leiomyosarcoma.

Adenocarcinoma↗
PubMed1994

Sonography of inflammatory bowel disease: findings and value in differential diagnosis.

OBJECTIVE: Inflammatory bowel diseases produce segmental or diffuse mural thickening of the intestine that can be detected and evaluated by using sonography. The purpose of this study was to evaluate the sonographic findings and determine their diagnostic value in patients with inflammatory bowel diseases. MATERIALS AND METHODS: We reviewed sonograms of 81 patients with inflammatory bowel diseases. The findings were compared with those of barium study, colonoscopy, and surgery. Forty-five patients had tuberculous enterocolitis, 13 had ulcerative colitis, eight had Crohn's disease, five had ischemic colitis, two had Behçet's syndrome, and eight had unspecified colitis. Diagnosis was based on surgical and pathologic findings in 23; results of barium study and endoscopic biopsy in 20; and results of barium study, colonoscopic findings, and clinical findings in 38. RESULTS: Seventy-two patients (89%) had sonograms that showed segmental or diffuse mural thickening and a paucity of luminal content in the involved bowel. Involved areas were the ileocecal region in the cases of tuberculous enterocolitis and Behçet's syndrome, the left side of the colon in ulcerative colitis, and the colon and terminal part of the ileum in Crohn's disease. In ischemic colitis, the distribution of involved bowel was nonspecific. Sonographic findings correlated well with the findings of barium enema or colonoscopy in terms of the involved segments of the bowel. Mesenteric lymphadenitis, omental thickening, and ascites were frequently observed in cases of tuberculous enterocolitis. CONCLUSION: Sonographic evidence of mural thickening of the bowel with a paucity of luminal content may be helpful in the detection of inflammatory bowel diseases. However, the findings are nonspecific, and the differential diagnosis must be related to the specific segment of the bowel involved.

Barium Sulfate↗
PubMed1994

Determining the site and causes of colonic obstruction with sonography.

OBJECTIVE: We studied the value of sonography in determining the site and cause of colonic obstruction. MATERIALS AND METHODS: Sonographic findings in 26 patients with known (n = 21) or suspected (n = 5) colonic obstruction on the basis of clinical findings and abdominal radiographs were correlated with radiologic and surgical findings. Colonic obstruction was proved in all with findings from surgery (n = 18) or from barium enema and CT (n = 8). Causes of the obstructions included colorectal cancer (n = 13), ileocolic intussusception (n = 11), transverse colonic adhesion (n = 1), and sigmoid volvulus (n = 1). Sonographic criterion of obstruction was the demonstration of a continuous distension of colonic loop with an abrupt transition to an empty distal colon. The value of sonography in terms of indicating the level and cause of colonic obstruction was evaluated. RESULTS: The location of colonic obstruction was established by using sonography in 22 (85%) of 26 cases, and the cause of obstruction was identified in 21 (81%) cases. Sonography depicted a mass (n = 5) or a segmental wall thickening (n = 5) in cases of colon cancer, and a target or doughnut sign in cases of ileocecal intussusception (n = 11). Sonography failed to depict the cause of obstruction in three cases of colon cancer and one case each of adhesion and sigmoid volvulus. CONCLUSION: Our experience suggests that sonography is useful for examining patients with colonic obstruction to determine the level and cause of the obstruction.

Adenocarcinoma↗
PubMed1994

Bilateral primary pigmented nodular adrenocortical disease--a case of report describing a rare cause of Cushing's syndrome.

A case of Cushing's syndrome due to bilateral pigmented nodular adrenal disease in a 35-year-old male is presented. The adrenals showed multiple, black, variable sized nodules. Histologically the cells contained lipofuscin and either had a clear cytoplasm or an eosinophilic cytoplasm with a prominent nucleus. Lymphocytic infiltration and fatty metaplasia within the nodules are two of the prominent histological features. There is extreme internodular atrophy which suggests that primary pigmented nodular adrenocortical disease is a non-adrenocorticotropic hormone dependent condition. Since the disorder appears to involve primarily the cortex of both adrenals, the treatment of choice is bilateral adrenalectomy followed by steroid replacement. The characteristic clinicopathological manifestations that separate this diagnosis from other types of adrenal disease are also discussed. This is the first reported case in Korea to be documented with the pertinent clinicopathological findings.

Adipose Tissue↗
PubMed1994

Sonography and color Doppler imaging of Budd-Chiari syndrome of membranous obstruction of the inferior vena cava.

We examined 18 patients with Budd-Chiari syndrome (membranous obstruction of the hepatic IVC). IVC obstruction was detected by sonography in 17 cases (94%). The causes were a web in 10 cases and a fibrous cord in four cases. In three cases, the cause was unspecified. Obliteration of the hepatic veins or intrahepatic collateral vessels or both was delineated in 16 cases (89%). With seven cases of color Doppler imaging, there was no detectable color or Doppler signal within the IVC, and the direction of hepatic venous blood flow through intravenous communications was fairly well demonstrated in all cases. In four cases of follow-up color Doppler imaging, the patency of the IVC was well demonstrated. Sonography is useful in detecting obstruction of the hepatic IVC and in demonstrating the hepatic venous obstruction and intrahepatic collateral vessels. Color Doppler sonography is useful in demonstrating the direction of blood flow through interconnecting vessels and in evaluating the patency of the IVC after treatment.

Adolescent↗
PubMed1993

Carcinoma of the ampulla of Vater: sonographic and CT diagnosis.

Twenty patients with carcinoma of the ampulla of Vater were studied with sonography (N = 9) or both sonography and CT (N = 11). The tumor was shown by sonography in 16 patients (80%) as a small, round or oval, fairly well delineated mass in between the dilated distal common bile duct and duodenum which was delineated owing to luminal fluid or gas (N = 13); or as a polypoid mass within the dilated distal common bile duct resulting in abrupt obstruction (N = 3). In the remaining four patients, the mass was not delineated. Bile ducts were dilated down to the level of mass or ampullary region in all cases (100%), while the pancreatic duct was dilated in five cases (45%). We believe that sonography is the technique of initial choice in the diagnosis of carcinoma of the ampulla of Vater by identifying the mass at the distal end of the dilated common bile duct and/or pancreatic duct.

Adenocarcinoma↗
PubMed1993

Small intestinal phytobezoars: sonographic detection.

Three cases of small intestinal phytobezoar, suggested by sonography and later confirmed at surgery, are reported. Sonographic findings of bezoar were intraluminal mass presenting as an arc-like surface echo casting clear posterior acoustic shadow within the lumen of the dilated small bowel. Compression of the mass with a transducer induced fluid shift around the mass. We propose that diagnosis of bezoars can be suggested on the basis of sonographic findings.

Aged↗
PubMed1993

Small bowel obstruction: sonographic evaluation.

Results of 54 sonographic examinations of patients referred for suspected or known small intestinal obstruction were retrospectively correlated with surgical findings, and the diagnostic value of sonography regarding presence, level, and cause of obstruction was compared with that of plain abdominal radiography. The diagnosis of obstruction was correct in 89% of cases with sonography and in 71% with plain radiography. The level of obstruction was correctly predicted in 76% of cases with sonography and in 51% with plain radiography. The cause of obstruction was correctly predicted in 20% of cases with sonography and in 2% with plain radiography. The authors conclude that use of sonography in evaluating patients with bowel obstruction may be helpful in confirmation of the presence of obstruction, in determination of the level of obstruction, and in identification of the cause of obstruction.

Adolescent↗