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Biomedical subjects

Y Seo

Publications and source records attributed to Y Seo.

At least 73 records · Page 4Linked to original sources
PubMed1998

Proton double-quantum filtered MRI--a new method for imaging ordered tissues.

The imaging of connective tissues such as cartilage and tendons using standard MRI techniques is hampered by their low signal relative to the surrounding tissues. 1H double-quantum filtered (DQF) MRI is an imaging method that detects molecules associated with ordered structures, while the signal from isotropic fluids is filtered out, thus creating a new type of contrast. The technique is demonstrated on an intact rat tail, where the image of the tendons is highlighted. Although the signal-to-noise ratio is inferior to that in gradient-echo MRI, the contrast between the tendons and the surrounding tissues is significantly better in the DQF MRI. It is demonstrated how, by adjusting the parameters of the DQF imaging pulse sequence, one can modify the contrast and enhance the images of specific compartments within an organ. A comparison with 2H DQF imaging of the same tissue is also given.

Animals↗
PubMed1998

Selective detection of biexponential relaxation in isotropic solutions by mixed coherence filtering NMR.

This is a trial to simplize sequences to get the relaxation function f31(t), which is usually detected by the double- or triple-quantum filtered (DQF or TQF) NMR in an isotropic phase. The results indicate that only two phase cycling is needed to get the f31(t) function, which shows the advantage of S/N (signal-to-noise ratio) in a minimum acquisition time. The filtering of coherence levels in the creation time need not be limited to double- or triple-quantum coherences. An 87Rb signal from a 4% (w/w) agar powder in 500-mM RbCl solution is recorded at 130.9 MHz as a Larmor frequency using a Bruker MSL 400 spectrometer.

Chlorides↗
PubMed1998

[Transcatheter stent-graft implantation for the treatment of acute aortic dissection--rupture of aneurysm because of perigraft leakage].

An 82-year-old woman was diagnosed as having acute type B aortic dissection. At bed rest, her systolic blood pressure was kept less than 120 mmHg. Four days later the aneurysm threatened to rupture. Because she presented a high operative risk for open-chest surgery, a stent-graft was implanted across the dissection site via transcatheter. The entry site to the aneurysm was closed by the stent-graft, and postoperative aortograph demonstrated that contrast medium did not enter the false lumen except for a trivial projection. A CT scan 6 days after the stent-graft implantation unexpectedly demonstrated the false lumen not only had not thrombosed, but had expanded. As a result, 8 days after the operation the aneurysm ruptured into the left pleural cavity, and the patient died. An autopsy revealed the stent-graft was exactly implanted across the entry site, but that the diameter of the graft was slightly larger than that of the aorta. Consequently, a portion of the rim of the graft had been wraped after implantation, causing perigraft leakage. Leakage is one of the gravest complications of the stent-graft implantation, to prevent it, a new design for stent-graft device is essential.

Acute Disease↗
PubMed1998

Five new polyacetylenes from a sponge of the genus petrosia

Petrocortynes D-H, novel C46 polyacetylenes, were isolated from a sponge of the genus Petrosia collected from Keomun Island, Korea. Petrocortyne D (2) is a 4,5-dihydro derivative of a diastereomer of petrocortyne A (1), and petrocortynes E-H (3-6) possess an additional allylic-hydroxyl group. The structures of these compounds were determined by combined chemical and spectral methods, and absolute configurations of most of the asymmetric carbon centers were determined by the modified Mosher's method. Limitations on the application of Mosher's method to allylic alcohols is discussed. Petrocortynes D-H exhibited moderate cytotoxicity and inhibitory activity against PLA2.

Journal Article↗
PubMed1998

New secosteroids from a gorgonian of the genus Muricella.

Calicoferols F-I (2-5), four new 9,10-secosteroids, have been isolated from a gorgonian of the genus Muricella collected from Jaeju Island, Korea. The structures of these compounds have been determined by combined spectroscopic methods. Calicoferols exhibited significant cytotoxicity and inhibitory activity against PLA2.

Animals↗
PubMed1998

Clinical significance of serum hyaluronic acid as a fibrosis marker in chronic hepatitis C patients treated with interferon-alpha: histological evaluation by a modified histological activity index scoring system.

The aim of the present study was to investigate the histological changes effected by interferon (IFN) treatment and to evaluate the clinical significance of serum hyaluronic acid (HA) as a marker of fibrosis. Forty-nine patients with chronic hepatitis C treated with IFN-alpha were divided into three groups according to the existence of viraemia: sustained complete responders (CR), complete responders with relapse (PR) and non-responders (NR). Needle biopsy sections of the liver taken before and at the end of IFN treatment were assessed according to the modified histological activity index (HAI) scoring system. Serum fibrosis markers, including HA, were measured at needle biopsies. Biopsies of CR at the end of treatment showed a significant improvement in fibrosis and necroinflammatory scores. More significant correlation was observed between fibrosis scores and serum levels of HA before IFN treatment (r = 0.607, P < 0.0001) than those between fibrosis scores, on the one hand, and peptide of type III procollagen (PIIIP; r = 0.531, P = 0.0004) or type IV collagen 7S domain (type IV-C; r = 0.241, P = 0.1062) on the other. Moreover, serum HA levels fell significantly in patients in whom fibrosis improved (P = 0.011). This is the first paper describing the advantages of the modified HAI scoring system over others in estimating the effect of IFN-alpha; the results also indicate that serum HA can be useful in monitoring liver fibrosis in chronic hepatitis C patients treated with IFN-alpha.

Adult↗
PubMed1998

Changes in sleep patterns during He-O2 saturation dives.

During simulated hyperbaric saturation diving experiments of He-O2 mixture at the depths of 150, 180 and 230 m the standard polysomnography of four divers, as well as their subjective feelings of fatigue, were recorded for 268 nights. In all three diving conditions, during the bottom period and the decompression period, wakes after sleep onset and Stage 1 sleep increased while Stage 4 sleep decreased. In deeper diving conditions stage 4 sleep tended to decrease and subjective feelings of fatigue increased. When the results are considered it can be assumed that the deeper the diving depths, the increased sleep disturbances and fatigue. However, it is believed that a fundamental sleep pattern will be maintained.

Adult↗
PubMed1998

Apoptosis following gamma knife radiosurgery in a case of acoustic schwannoma.

A 25-year-old woman with a large acoustic schwannoma underwent surgical excision 18 months after Gamma Knife radiosurgery because of transient expansion of the tumor causing ataxia. Histopathologial investigation by the TUNEL method revealed the presence of some apoptotic cells. The findings were compared with findings from a control group of 7 operated cases where radiosurgery had not been used. There was no apoptosis found in any of these cases. In addition, another case which resulted in a regrowing tumor following Gamma Knife treatment also showed no apoptosis. These findings suggest apoptosis may be a possible mechanism in reducing tumor size following Gamma Knife radiosurgery.

Adult↗
PubMed1998

NMR studies of salivary glands: from energy metabolism to morphology.

Nuclear magnetic resonance (NMR) spectroscopy has been used to study various physiological functions of salivary glands. This short review summarizes results on energy metabolism and acid-base balance (31P and 14N NMR), electrolytes transport (23Na, 39K, 35Cl and 87Rb NMR) and water transport (1H NMR). The latest development of 1H nuclear magnetic resonance imaging (MRI) allows the three-dimensional structure of salivary glands to be observed with ca. 60 microm resolution, and it is also possible to observe circulation, flow, and volume changes during secretion. The combination of NMR and MRI may open up new fields in the study of exocrine secretion.

Acid-Base Equilibrium↗
PubMed1998

Regulation of cell volume and diffusion of intracellular water in salivary acinar cells.

The regulation of acinar cell volume and the properties of intracellular water were investigated in perfused rat mandibular salivary glands by proton nuclear magnetic resonance (NMR) spectroscopy. Using an inversion-recovery pulse sequence, and an extracellular relaxation reagent (10 mM Gd-DTPA) to suppress the proton NMR signal from extracellular water, acinar cell volume (intracellular water content) in unstimulated glands was shown to depend upon Cl- uptake by basolateral Na+-K+-2Cl- cotransport. Muscarinic and beta-adrenoceptor stimulation induced shrinkage and swelling respectively. In pulsed-field-gradient NMR experiments, the diffusion coefficient of intracellular water was found to be more than an order of magnitude smaller than that of extracellular water. Using this intrinsic difference in diffusivity between the two compartments, cell volume regulation was investigated in intact, perfused glands in the absence of relaxation reagents. Using both NMR techniques, acinar cells in perfused glands were observed to behave like simple osmometers in response to anisosmotic media, and did not show the volume regulatory responses described in dissociated acinar cells.

Animals↗
PubMed1998

Energy consumption associated with fluid and electrolyte transport in the mandibular and parotid glands.

The driving force for Cl- secretion in the salivary acinar cell is believed to be provided by the secondary active uptake of Cl- by Na+ dependent basolateral transporters. The energy cost of primary fluid secretion should therefore reflect the ratio of Na+ entry per mole of Cl- secreted. In the present study, we measured oxygen consumption (QO2) and fluid secretion in perfused mandibular and parotid glands from the rat, and estimated the energy cost of fluid secretion as the ratio of deltaQO2/delta(fluid secretion). During acetylcholine stimulation, the energy cost of fluid secretion by secretory endpieces was higher in the parotid gland than in the mandibular gland. The excess energy cost in the parotid gland may be attributable to other costs than the fluid and electrolyte transport. During bicarbonate-free perfusion in the mandibular gland, bumetanide abolished fluid secretion and QO2 decreased by ca 35%. The remaining QO2 was attributed to Na+ transport activity by basolateral antiports. Assuming values for the energy costs of each transporter and applying these to the total energy cost of the endpieces, the fraction of the total Na+ flux due to Na+/K+/2Cl- cotransport in Na+ handling was estimated to be 0.67. On the other hand, during perfusion with bicarbonate, after subtraction of the bumetanide-sensitive QO2 and the QO2 for antiports, about 19 microl/g/min of QO2 remained, which may be due to activation of Na+/HCO3- cotransport. Thus the inclusion of bicarbonate in the perfusate appears to alter the relative contributions of the various Na+-dependent basolateral transporters to total Na+ handling.

Animals↗
PubMed1997

A sandwich enzyme immunoassay for brain S-100 protein and its forensic application.

A sensitive sandwich enzyme immunoassay for identification of brain S-100 protein in blood or bloodstains containing brain tissue is described. A polystyrene ball coated with rabbit anti-S-100 protein IgG was incubated with human S-100 protein, and then with anti-S-100 Fab'-peroxidase conjugate. Peroxidase activity bound to the polystyrene ball was assayed by fluorometry using 3-(4-hydroxyphenyl)propionic acid as the hydrogen donor. The detection limit of human S-100 protein was 0.6 pg (30 amol) per assay tube. The cross-reaction of this sandwich enzyme immunoassay to other organs was approximately 1/100 or less. Antigenic activity of S-100 protein in bloodstains containing brain extracts was detectable after storage for 36 days at room temperature. The ratio of S-100 protein to total protein (ng/mg) in bloodstains when brain tissue was mixed with normal human blood at concentrations of 5-500 mg/ml was approximately 100-fold those of other samples (liver, heart, intestine, and skeletal muscle). These results indicated that bloodstains mixed with brain tissue were clearly distinguishable from others. Thus, in forensic practice, measurement of S-100 protein or the ratio of S-100 protein to total protein is useful to identify blood and bloodstains containing brain tissue.

Blood Stains↗
PubMed1997

Overexpression of SAP-1, a transmembrane-type protein tyrosine phosphatase, in human colorectal cancers.

SAP-1 is a human transmembrane-type protein tyrosine phosphatase that is abundant in colon and pancreatic cancer cell lines. The expression of SAP-1 in surgically excised human colorectal cancer specimens has now been investigated by immunohistochemical staining and in situ hybridization. Normal colon tissue or adenomas with mild dysplasia showed no detectable expression of SAP-1. In contrast, 2 of 17 adenomas with moderate or severe dysplasia and 19 of 48 (40%) adenocarcinomas expressed SAP-1, SAP-1 was localized predominantly to the apical surface of colonic cells in adenoma tissue showing moderate dysplasia, but it was also observed in the cytoplasm and at the basal surface of both adenoma cells showing severe dysplasia and adenocarcinoma cells. In situ hybridization with a SAP-1 antisense RNA probe detected SAP-1 mRNA in 6 of 9 colorectal cancers, but not in the surrounding mesenchymal tissue or normal mucosa. Sequencing of the K-RAS gene revealed that 10 of 15 (67%) SAP-1-positive cancers contained a mutation in codon 12. The serum concentration of carcinoembryonic antigen was normal in approximately half of the patients with SAP-1-positive colorectal cancers. These results suggest that SAP-1 is frequently overexpressed in human colorectal cancers and that such overexpression may occur relatively late in the adenoma-carcinoma sequence.

Adenocarcinoma↗
PubMed1997

Stent placement for recurrent vasospastic angina resistant to medical treatment.

The successful stent placement for treatment of recurrent vasospastic angina in a patient with nonstenotic coronary arteries is described. Use of the Palmaz-Schatz stent resulted in successful vasodilation that completely prevented anginal attacks. This procedure represents an alternative treatment for patients with vasospastic angina refractory to aggressive medical therapy.

Angina Pectoris, Variant↗
PubMed1997

Micro-magnetic resonance imaging of the inner ear in the guinea pig.

We applied a magnetic resonance microscopy at 7.05 T with a gradient coil unit to image the fine structure of the guinea pig cochlea. First, a three-dimensional MR image of the surface of the cochlea was obtained to select the location of cross-sectional images. Then, cross-sectional images of the basal turn, the second turn and the apical turn of the cochlea were obtained. Based upon the different protein concentrations of the endolymph vs the perilymph, the scala vestibuli, scala tympani and the cochlear duct could be clearly distinguished. This allowed a determination of the location of both the basilar membrane and Reissner's membrane. We raise the possibility that MRM may become useful in the diagnosis of endolymphatic hydrops (Meniere's disease).

Animals↗
PubMed1997

Discrimination between the different compartments in sciatic nerve by 2H double-quantum-filtered NMR.

The 2H double-quantum-filtered (DQF) NMR spectrum of isolated rat sciatic nerve, equilibrated with deuterated saline, is composed of three quadrupolar-split water signals. On the basis of the time course of their shift by Co-EDTA2- and CoCl2, the signals with quadrupolar splittings of about 120, 470, and 9 Hz were assigned to water in the epineurium, endoneurium, and intra-axonal compartments, respectively. The signal of the bulk water, which experiences isotropic motion, was eliminated by the DQF pulse sequence. As the maximum intensities of the water signals in the three anisotropic compartments occur at different creation times, in the DQF pulse sequence, it is possible to resolve the signals and measure their properties, such as relaxation times, independently, without perturbing the system with shift reagents.

Animals↗
PubMed1997

Sesquiterpenoids of the drimane class from a sponge of the genus Dysidea.

Ten sesquiterpenoids, including seven new ones, have been isolated from an undescribed sponge of the genus Dysidea. Compounds 1-8 are sesquiterpenoids of the drimane class, while 9 and 10 are 12-norsesquiterpenoids of the same structural class. The structures of novel compounds have been determined by combined spectroscopic methods. These compounds exhibited moderate antimicrobial and enzyme inhibitory (Na+/K(+)-ATPase and PLA2) activities.

Animals↗