Biomedical subjects

Y M Shin

Publications and source records attributed to Y M Shin.

At least 19 recordsLinked to original sources

PubMed2003

A biodegradable nanofiber scaffold by electrospinning and its potential for bone tissue engineering.

Microporous, non-woven poly( epsilon -caprolactone) (PCL) scaffolds were made by electrostatic fiber spinning. In this process, polymer fibers with diameters down to the nanometer range, or nanofibers, are formed by subjecting a fluid jet to a high electric field. Mesenchymal stem cells (MSCs) derived from the bone marrow of neonatal rats were cultured, expanded and seeded on electrospun PCL scaffolds. The cell-polymer constructs were cultured with osteogenic supplements under dynamic culture conditions for up to 4 weeks. The cell-polymer constructs maintained the size and shape of the original scaffolds. Scanning electron microscopy (SEM), histological and immunohistochemical examinations were performed. Penetration of cells and abundant extracellular matrix were observed in the cell-polymer constructs after 1 week. SEM showed that the surfaces of the cell-polymer constructs were covered with cell multilayers at 4 weeks. In addition, mineralization and type I collagen were observed at 4 weeks. This suggests that electrospun PCL is a potential candidate scaffold for bone tissue engineering.

Animals↗

PubMed2001

p16(INK4a) Promoter hypermethylation of non-tumorous tissue adjacent to gastric cancer is correlated with glandular atrophy and chronic inflammation.

The p16(INK4a) tumor suppressor gene can be inactivated by promoter region hypermethylation in many tumor types including gastric cancers. However, p16(INK4a) promoter hypermethylation in the surrounding non-tumorous tissues of gastric cancers has not been studied in detail. We therefore examined 46 gastric cancers, corresponding adjacent non-tumorous tissue samples and 8 gastric tissue samples of chronic gastritis by performing methylation-specific polymerase chain reaction, and we analyzed p16(INK4a) protein expression using immunohistochemistry and Western blot. p16(INK4a) promoter hypermethylation was observed in 43% of gastric cancers and 59% of adjacent non-tumorous tissues; however, none of the samples retrieved from the chronic gastritis patients displayed p16(INK4a) promoter hypermethylation. Gastric cancers showed an inverse correlation between vascular invasion and p16(INK4a) promoter hypermethylation, and adjacent non-tumorous tissues displayed a close association among the grade of chronic inflammation, presence of glandular atrophy and p16(INK4a) promoter hypermethylation. p16(INK4a) expression was markedly decreased in samples with p16(INK4a) promoter hypermethylation when compared with samples without p16(INK4a) promoter hypermethylation. These results suggest that p16(INK4a) promoter hypermethylation is an early and frequent event in gastric carcinogenesis and may serve as a new prognostic biomarker for the risk of gastric cancers.

Atrophy↗

PubMed2001

Slow transit constipation in children.

Patients with chronic constipation that fails to respond to treatment remain a challenge for paediatricians and surgeons. Ongoing work in our institution suggests that a number of children with intractable symptoms have slow transit constipation, which has only been described recently in paediatrics. Common features of slow transit are: delayed passage of the first meconium stool beyond 24 h of age, symptoms of severe constipation within a year, or treatment-resistant 'encopresis' at 2-3 years, soft stools despite infrequent bowel actions, and delay in colonic transit on a transit study. A proportion of children with slow transit constipation have an abnormality of intestinal innervation associated with the dysfunctional colonic motility, recognized as intestinal neuronal dysplasia (IND). Intestinal neuronal dysplasia type B, the most common variant of IND, is defined on rectal biopsy by hyperplasia of the submucosal plexus. On laparoscopic colon muscle biopsy, many specimens show reduced numbers of excitatory substance P-immunoreactive nerve fibres in the circular muscle. Functional markers of the nerves allow new diagnostic criteria to be developed which may also allow a more rational approach to treatment. The aetiology remains obscure and the optimal management poorly defined, although subtotal colectomy, proximal colostomy or appendicostomy (for antegrade enemas) have been tried. Once the anatomy and physiology of the colon in children with slow colonic transit is better understood, we will have defined not only a new form of constipation, but also will be able to consider new therapies.

Child↗

PubMed2001

Enhanced iron uptake of Saccharomyces cerevisiae by heterologous expression of a tadpole ferritin gene.

We genetically engineered Saccharomyces cerevisiae to express ferritin, a ubiquitous iron storage protein, with the major heavy-chain subunit of tadpole ferritin. A 450-kDa ferritin complex can store up to 4,500 iron atoms in its central cavity. We cloned the tadpole ferritin heavy-chain gene (TFH) into the yeast shuttle vector YEp352 under the control of a hybrid alcohol dehydrogenase II and glyceraldehyde-3-phosphate dehydrogenase promoter. We confirmed transformation and expression by Northern blot analysis of the recombinant yeast, by Western blot analysis using an antibody against Escherichia coli-expressed TFH, and with Prussian blue staining that indicated that the yeast-expressed tadpole ferritin was assembled into a complex that could bind iron. The recombinant yeast was more iron tolerant in that 95% of transformed cells, but none of the recipient strain cells, could form colonies on plates containing 30 mM ferric citrate. The cell-associated concentration of iron was 500 microg per gram (dry cell weight) of the recombinant yeast but was 210 microg per gram (dry cell weight) in the wild type. These findings indicate that the iron-carrying capacity of yeast is improved by heterologous expression of tadpole ferritin and suggests that this approach may help relieve dietary iron deficiencies in domesticated animals by the use of the engineered yeast as a feed and food supplement.

Animals↗

PubMed2000

Expression of glucose oxidase by using recombinant yeast.

The glucose oxidase gene (GO) of Aspergillus niger was cloned into the yeast shuttle vector YEp352 with combinations of various promoters and terminators, and then used to transform Saccharomyces cerevisiae. Expressed GO was successfully secreted into culture medium due to the presence of the intrinsic signal peptide of GO. Four different promoters fused to GO were tested: bidirectional galactose dehydrogenase 1 and 10 (GAL1, GAL10) promoters, glyceraldehyde-3-phosphate dehydrogenase (GPD) promoter and an yeast hybrid ADH2-GPD promoter consisting of alcohol dehydrogenase II (ADH2) and GPD promoter. The intrinsic terminator of GO as well as the GAL7 terminator were also compared for better production of GO. Deletion of most of the terminating region from GO yielded only a slight amount of GO while the presence of either terminator greatly increased GO production. The GAL10 promoter produced the least amount of GO, GAL1 and GPD promoters were moderate, and the ADH2-GPD hybrid promoter was the best among all tested. However, the hybrid promoter was tightly regulated by the presence of an excess amount of either glucose or ethanol, and it appeared that 2% glucose and 1. 5% ethanol supplement was the best concentration for GO production. It was possible to produce 260 IU ml(-1) of GO, an equivalent of 5 g l(-1), under the presence of 2% glucose and 1.5% ethanol. UV mutagenesis of a recombinant S. cerevisiae was also applied and it further increased the yield of GO to 460 IU ml(-1) under the presence of 2% glucose and 1.5% ethanol without any changes in cell growth. Corn steep liquor which is commonly used in bioindustry is a good alternative substrate for high priced glucose for the hybrid promoter and suggests a cost effective means for commercial mass production of GO using recombinant yeast.

Biotechnology↗

PubMed1998

Immunoglobulin E-dependent active fatal anaphylaxis in mast cell-deficient mice.

Mast cells have long been believed to be the central effector cells in the development of immunoglobulin (Ig)E-dependent anaphylaxis. In this study, we investigated the role of mast cells in IgE-dependent hapten-induced active fatal anaphylaxis using mast cell-deficient WBB6F1- W/Wv (W/Wv) and congenic normal (+/+) mice. Although a 5-min delay in shock signs and death were observed in W/Wv mice, 100% fatal reactions to penicillin V (Pen V) occurred in both +/+ and W/Wv mice. Administration of monoclonal anti-IL-4 antibody completely prevented the fatal reactions, and the effect of anti-IL-4 was associated with its suppressive activity on Pen V-specific serum levels of IgE, but not IgG. The platelet-activating factor (PAF) antagonist, BN 50739, completely prevented the fatal reactions in both strains of mice. Our kinetic study revealed, in contrast to no elevation of plasma histamine level in W/Wv mice, high levels of PAF in the circulation after challenge in both +/+ and W/Wv mice, albeit to a lesser degree in the latter case. These data indicate that cells other than mast cells are sufficient to induce an IgE-dependent active fatal anaphylaxis by elaborating PAF, which is the critical mediator for fatal murine anaphylaxis.

Anaphylaxis↗

PubMed1998

Intestinal Behçet syndrome: CT features of patients with and patients without complications.

PURPOSE: To analyze the computed tomographic (CT) features of intestinal Behçet syndrome and to determine the usefulness of CT in detecting complications. MATERIALS AND METHODS: The CT scans of 28 patients with intestinal Behçet syndrome were retrospectively reviewed. Five patients had bowel perforation, and two had peritonitis. Patterns of bowel involvement, patterns of contrast enhancement, and ancillary findings were compared in patients with complications (n = 7) and patients without complications (n = 21). RESULTS: Ten patients had polypoid lesions, nine had a thickened bowel wall, and nine had both findings. Lesion enhancement was mild in eight patients (29%) and marked in 20 (71%). Polypoid lesions were more commonly seen in patients without complications (P = .020); a thickened bowel wall was more commonly seen in patients with complications (P = .030). Seventeen of 18 patients (94%) with minimal perienteric infiltration did not have complications (P = .0003), whereas all five patients with severe perienteric infiltration did have complications. CONCLUSION: In patients with known intestinal Behçet syndrome, CT can be useful in determining the extent of the lesions and in identifying cases in which complications are likely to occur.

Adult↗

PubMed1998

MR cholangiopancreatography of pancreaticobiliary diseases: comparing single-shot RARE and multislice HASTE sequences.

OBJECTIVE: In this study, we compared the single-shot rapid acquisition with relaxation enhancement (RARE) sequence with the multislice half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence to assess the ability of each technique to show various pancreaticobiliary diseases using MR cholangiopancreatography. SUBJECTS AND METHODS: MR cholangiopancreatography was performed using both the single-shot RARE and the multislice HASTE pulse sequences in 80 consecutive subjects in whom we had proof of a range of diagnoses. The study population included healthy subjects (n = 9), patients with benign lesions (n = 41), and patients with malignant lesions (n = 30). We analyzed each image using the following criteria: the cause of the lesions, the image quality (i.e., the amount of artifact and the sharpness of anatomic structures such as the right and left hepatic ducts, the extrahepatic bile duct, and the main pancreatic duct), and the reviewers' preference of images. The images were evaluated independently by two radiologists who were unaware of the results of the other cholangiopancreatographic sequence and of the diagnosis. RESULTS: Artifacts were less prominent in images that were obtained using the single-shot RARE sequence (p = .0192); however, the sharpness of anatomic structures was the same using either sequence (p = .1673). For images that were obtained using the single-shot RARE technique, the sensitivity, specificity, and accuracy in distinguishing malignant from other abnormalities were 83%, 78%, and 80%, respectively; for the multislice HASTE technique, these values were 77%, 72%, and 74%, respectively (p > .05). Disease-specific accuracy in determining the correct diagnosis was 54% and 59%, respectively (p > .05). In patients in whom all the ducts needed to be defined, the single-shot RARE technique was preferred to the multislice HASTE technique (p < .01). CONCLUSION: The single-shot RARE technique shows fewer artifacts and is preferred to the multislice HASTE technique. However, both techniques show the same degree of sharpness of anatomic structures, both are able to reveal malignant diseases, and both provide enough information to determine a specific diagnosis.

Adult↗

PubMed1997

MR imaging of segmental renal infarction: an experimental study.

An experimental study was performed in 12 rabbits to evaluate the magnetic resonance (MR) imaging findings of segmental renal infarction. Three or four MR examinations were performed at 6 h, 1 day, 3 days, 1 week, 2 weeks, and 4 weeks following the ligation of segmental artery of the left kidney. The signal intensities of the infarcted area on both T1- and T2-weighted (T1W and T2W, respectively) images were lower than those of the non-affected area in the 6 h group, and pathological examination showed mild interstitial oedema and haemorrhage. The signal intensities of the lesion became higher on T1W images and higher or mixed on T2W scans in the 1 day group, in which the pathological findings were intense interstitial haemorrhage, interstitial oedema, and early coagulative necrosis. The signal intensities of the lesion on both pulse sequences were also higher in the 3 day and 1 week groups in which pathological examination showed progressive coagulative necrosis. The signal intensities of the lesions in the 2 and 4 week groups were lower on both pulse sequences, and the pathological finding was organizing fibrosis. Post-contrast T1W images demonstrated well the extent of the infarction in all but two cases, in which the signal intensities of the lesions were higher on pre-contrast T1W scans.

Animals↗

PubMed1993

Pulmonary paragonimiasis: clinical and experimental studies.

Pulmonary paragonimiasis is a disease caused by a lung fluke. It is endemic to East Asia, but there have been several case reports in North America. Human infestation occurs by ingestion of raw or incompletely cooked freshwater crab or crayfish infected with metacercaria. A retrospective study was performed with 78 patients who lived in South Korea and had chest radiographic findings of pleuropulmonary disease; it was subsequently shown that they had paragonimiasis. The diagnosis was based on positive results of serologic tests for Paragonimus-specific antibody or on the detection of eggs in sputum samples. Radiologic findings from these 78 patients were correlated with the pathologic and radiologic findings from a study of experimentally induced pulmonary paragonimiasis in 21 cats. Findings from the correlative study document that the typical radiologic manifestations of pulmonary paragonimiasis vary with the stage of the disease. Early findings include pneumothorax or hydropneumothorax, focal airspace consolidation, and linear opacities and are caused by the migration of juvenile worms. Later findings include thin-walled cysts, dense masslike consolidation, nodules, or bronchiectasis and are due to worm cysts.

Adult↗

PubMed1993

Gliomatosis cerebri: comparison of MR and CT features.

OBJECTIVE: Gliomatosis cerebri is a diffuse infiltrative glial neoplasm frequently involving both cerebral hemispheres. Diagnosis and evaluation of its extent with CT are known to be difficult. The purpose of this study was to compare the MR and CT findings in gliomatosis cerebri. MATERIALS AND METHODS: MR images of nine patients were reviewed retrospectively and compared with CT scans. Pathology was determined by open or stereotaxic biopsy. The MR images included sagittal T1-weighted, axial proton density-weighted, and T2-weighted images. Contrast material was administered in seven patients. Unenhanced and enhanced CT scans were obtained in eight patients. RESULTS: On proton density-weighted and T2-weighted MR images, the most common findings were poorly defined bilateral areas of diffuse high signal intensity in the cerebral hemisphere. On T1-weighted images, the lesions were isointense to hypointense compared with normal brain. Enhanced T1-weighted images showed focal parenchymal enhancement in three patients and meningeal enhancement in one. On CT scans, the lesions showed poorly defined areas of subtle low density or isodensity, and appeared much smaller than those on T2-weighted MR images. Enhancement was seen in only one case. The extent of disease was evaluated much better on T2-weighted MR images than on T1-weighted MR images and CT scans. CONCLUSION: In gliomatosis cerebri, MR imaging is more sensitive than CT for detecting lesions and shows the extent of disease better than CT does. Accordingly, MR imaging should be used as a primary imaging study in the evaluation of gliomatosis cerebri.

Adult↗

PubMed1988

Synthesis and thromboxane A2 antagonist activity of N-benzyltrimetoquinol analogues.

It is currently believed that the platelet thromboxane A2 (TXA2/PGH2) receptor is different from the vascular TXA2/PGH2 receptor. While the majority of TXA2 receptor antagonists are structurally related to the prostaglandins, trimetoquinol (TMQ) represents a unique nonprostanoid antagonist. TMQ also possesses beta-adrenergic activity; however, an N-benzyl substituent on TMQ has been shown to impart some selectivity for platelet antiaggregatory activity versus beta-adrenergic activity. In this study, we examined the synthesis and TXA2 antagonist activity of a series of substituted N-benzyl analogues of TMQ. While these analogues showed an apparent direct correlation between platelet antiaggregatory activity and electron-donating ability of the N-benzyl substituents, no such correlation could be demonstrated for the inhibition of contractile responses. Thus, nonprostanoid TXA2 antagonists can be used to demonstrate differences between platelet and vascular TXA2/PGH2 responses.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMedDate not supplied

Application of MRI for small intestinal diseases.

Until recently, MRI has not been considered to be suitable for the evaluation of the small intestine due to artifacts associated with bowel peristalsis or respiration. However, recent advances of MR techniques enable the acquisition of clear images of the small intestine. Therefore, the purpose of this article is to review the details for the application of MRI in patients with small intestinal diseases. This article discusses bowel preparation and oral contrast agents as well as MR techniques and pulse sequences. Thereafter, the usefulness of MRI for the lesions in the peritoneal cavity or in the gastrointestinal tract are discussed. Small intestinal lesions are categorized into inflammatory, neoplastic, ischemic, and obstructive bowel diseases. In conclusion, MRI can be used as an alternate modality of choice for imaging various diseases of the small intestine.

Administration, Oral↗

PubMedDate not supplied

MR findings of hepatic cavernous hemangioma after intraarterial infusion of iodized oil.

Magnetic resonance (MR) imaging was performed on five tumors of three patients who had hepatic hemangiomas. Four tumors were given an intraarterial infusion of 3-8 ml of iodized oil, while one tumor was not. MR images were obtained at 2.0 or 0.5 T. A single spin echo sequence with TE of 30 ms and TR of 500 ms and a double echo sequence with TEs of 60 and 150 ms and TR of 2000 ms, were used to produce relatively T1-, T2-weighted, and heavily T2-weighted images, respectively. Follow-up MR imaging was done 1-5 months after infusion of iodized oil. On relatively T1-weighted images, hemangiomas showed iso- or hypointensity. On T2-weighted images, all tumors showed hyperintensity. However, on heavily T2-weighted images, tumors with iodized oil showed heterogeneous, slight hyperintensity, while tumors without iodized oil showed characteristic appearance of marked hyperintensity in hemangiomas. In hepatic cavernous hemangiomas with intraarterial infusion of iodized oil, familiarity with this unusual MR intensity of tumors on heavily T2-weighted images is useful to avoid the incorrect diagnosis and to reduce the frequency of inappropriate hepatic resection.

Female↗

PubMedDate not supplied

Peripheral cholangiocarcinoma: comparison of MRI with CT.

To evaluate the clinical utility of computed tomography (CT) and magnetic resonance imaging (MRI) in the diagnosis of peripheral cholangiocarcinoma of the liver, 11 patients with pathologically proven peripheral cholangiocarcinoma were examined with both CT and MRI. On CT scans in 10 cases, the tumors appeared as irregular, low-attenuation masses with a wide variation in heterogeneity. Contrast enhancement of the tumors was mild in nine cases and moderate in one case, at the periphery. Tumor was not identified in one case. On T1-weighted MRIs, the tumors showed low intensity in eight cases and isointensity in three cases. On T2-weighted images, the tumors showed high intensity in all 11 cases. Focal dilatation of the intrahepatic bile ducts around the tumor was seen in one case on MRIs and in four cases on CT scans. Portal vein invasion of the tumors was seen in one case, and lymphadenopathy was seen in four cases on both MRIs and CT scans. MRI was slightly superior to CT in detecting the tumors, was inferior to CT in delineating focal ductal dilatation around the tumors, and was equal to CT in assessing extent of the tumors.

Aged↗

PubMedDate not supplied

Abdominal cavernous Iymphangiomas: CT findings.

Two adult patients with histopathologically proved cavernous lymphangiomas and one adult patient with lymphangiomas of strongly presumed cavernous type by cytologic and computed tomographic findings are reported. On computed tomograms, multiple, aggregated, small, and tiny cysts without a solid portion, along the lymphatic channels are characteristic computed tomographic findings for cavernous lymphangiomas.

Abdominal Neoplasms↗

PubMedDate not supplied

Diagnostic pitfalls in the cholangiographic diagnosis of choledochoceles: cholangiographic quality and its effect on visualization.

BACKGROUND: We wanted to establish reasonable cholangiographic diagnostic criteria by determining the sensitivity of cholangiography in detecting choledochoceles and those factors that could compromise visualization of choledochoceles. METHODS: Over 4 years, 21 patients (seven male, 14 female; mean age = 67 years) were confirmed as having choledochoceles on endoscopic retrograde cholangiopancreatography (ERCP). Cholangiographic diagnosis was made by following three criteria: a radiolucent halo around the distal common bile duct (CBD), bulbous dilatation of the distal CBD, and the presence of sequential morphologic changes on serial cholangiography. Any two or more combinations of these three criteria were considered enough to diagnose a choledochocele on cholangiography. We compared cholangiographic imaging findings with the ERCP results. RESULTS: Of 21 patients with choledochoceles, nine (43%) were correctly diagnosed on cholangiography. A radiolucent halo was present in six (28%) patients; four of these cases showed optimal duodenal filling, one showed faint duodenal filling, and one showed poor duodenal filling. The shapes of the distal CBD were bulbous, conelike, and blunt. Morphologic changes such as collapsing and bulging of the choledochocele could be seen in 12 (57%) patients on serial cholangiography. Waists were seen in 11 (52%), pseudowebs in four (19%), and wrinkling of the distal CBD in seven (33%). CONCLUSION: Cholangiography should be obtained with optimal timing and adequate conditions to diagnose choledochocele correctly.

Aged↗

PubMedDate not supplied

Focal hepatic nodules after transcatheter oily chemoembolization; detection with spiral CT versus conventional CT.

BACKGROUND: The objective of this study was to determine if spiral computed tomography (CT) results in increased rate of detection of focal hepatic nodules containing iodized oil after transcatheter oily chemoembolization when compared with conventional CT. METHODS: Spiral CT with single 24-s breath-hold technique was compared with conventional sequential CT in 42 patients with suspected hepatocellular carcinomas. Two sets of CT scans obtained after transcatheter oily chemoembolization were independently reviewed by two radiologists. The slice thickness was 10 mm for both data sets. The number and sizes of focal hepatic nodules containing iodized oil were documented. All 42 patients had at least hepatic nodule. The lesion size varied from 2 mm to 12 cm. RESULTS: In six of the 42 patients, more hepatic nodules could be identified on spiral CT compared with conventional CT. When scans with spiral CT were used, 107 nodules were detected, whereas 98 nodules were detected with conventional CT. Overall, nine (9%) more nodules were detected with spiral CT (p = .002). If lesions larger than 2 cm are excluded, nine (15%) more lesions were detected with spiral CT (p = .002). CONCLUSION: Spiral CT results in increased rate of detection of focal hepatic nodules after transcatheter oily chemoembolization, particularly in lesions smaller than 2 cm.

Antibiotics, Antineoplastic↗