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Biomedical subjects

Y Kim

Publications and source records attributed to Y Kim.

At least 433 records · Page 24Linked to original sources
PubMed1998

MCG simulations of myocardial infarctions with a realistic heart-torso model.

Data from simulations of the anterior myocardial infarction (AMI) and inferior myocardial infarction (IMI) are presented. One infarct located in the anterior section of the left ventricle and a second one in the inferior wall of the left ventricle were modeled. A high-resolution finite element model of a heart and torso was used in this study. Differences in the normal and infarcted fields were computed. Our data suggest that the infarcted region contribution to the total magnetic field can be accounted for by an equivalent current dipole. It might also be possible to detect an infarct from these difference fields constructed for different cases of myocardial infarction. More simulations are needed to determine the relations between infarct sizes and locations and magnetic fields. These relations might then be used to detect various cases of myocardial infarction.

Biophysical Phenomena↗
PubMed1998

MCG simulations with a realistic heart-torso model.

Magnetocardiograms (MCG's) simulated with a high-resolution heart-torso model of an adult subject were compared with measured MCG's acquired from the same individual. An exact match of the measured and simulated MCG's was not found due to the uncertainties in tissue conductivities and cardiac source positions. However, general features of the measured MCG's were reasonably represented by the simulated data for most, but not all of the channels. This suggests that the model accounts for the most important mechanisms underlying the genesis of MCG's and may be useful for cardiac magnetic field modeling under normal and diseased states. MCG's were simulated with a realistic finite-element heart-torso model constructed from segmented magnetic resonance images with 19 different tissue types identified. A finite-element model was developed from the segmented images. The model consists of 2.51 million brick-shaped elements and 2.58 million nodes, and has a voxel resolution of 1.56 x 1.56 x 3 mm. Current distributions inside the torso and the magnetic fields and MCG's at the gradiometer coil locations were computed. MCG's were measured with a Philips twin Dewar first-order gradiometer SQUID-system consisting of 31 channels in one tank and 19 channels in the other.

Adult↗
PubMed1998

Pubic arch detection in transrectal ultrasound guided prostate cancer therapy.

New biopsy techniques, increased life expectancy, and prostate-specific antigen (PSA) screening have contributed to an increase in the reported incidence of prostate cancer. Among several treatment options available to the patients, transperineal prostate brachytherapy has emerged as a medically successful, cost-effective outpatient procedure for treating localized prostate cancer. Transperineal prostate brachytherapy employs transrectal ultrasound (TRUS) as the primary imaging modality to accurately preplan and subsequently execute the placement of radioactive seeds into the prostate. Under TRUS guidance, a needle (preloaded with radioactive seeds) is inserted through a template guide, through the perineum and into a predetermined prostate target. The pubic arch, formed by the central union of pelvic bones, is a potential barrier to the passage of these needles in the prostate. A critical aspect, therefore, in the planning and execution of the brachytherapy procedure is the accurate assessment of pubic arch interference (PAI) in relation to the prostate. Traditionally, the evaluation of PAI has involved computed tomography correlate scanning or crude subjective evaluations. In this paper, we describe a new method of assessing PAI by detecting the pubic arch via image processing on the TRUS images. The PAI detection (PAID) algorithm first uses a technique known as sticks to selectively enhance the contrast of linear features in ultrasound images. Next, the enhanced image is thresholded via percentile thresholding. Finally, we fit a parabola (a model for the pubic arch) recursively to the thresholded image. Our evaluation result from 15 cases indicates that the algorithm can successfully detect the pubic arch with 90% accuracy. Based on this study, we believe that detecting the pubic arch and assessing PAI can be done practically and more accurately in the clinical setting using TRUS rather than the current available methods.

Brachytherapy↗
PubMed1998

Progressive viral-induced cirrhosis: serial MR imaging findings and clinical correlation.

PURPOSE: To determine which magnetic resonance (MR) imaging findings of cirrhosis change as disease severity progresses. MATERIALS AND METHODS: Seventy-six abdominal MR imaging studies in 38 patients (two per patient) with Child-Pugh grade A cirrhosis were retrospectively reviewed. All patients were followed up clinically and with MR imaging for 12 months or longer. MR images were used to determine volume indexes of the spleen and of each liver segment, as well as changes in hepatic contour, iron or fat deposition, and presence of varices and collateral vessels. RESULTS: During follow-up in patients with progressive cirrhosis (n = 13), the volume indexes of the anterior, posterior, and medial segments of the liver decreased significantly (P = .011, .013, .002, respectively), and the number of varices and collateral vessels increased significantly (P = .018). In patients with stable cirrhosis (n = 25), the volume indexes of the spleen, caudate lobe, and lateral segment increased significantly (P = .032, .018, .003, respectively). The atrophic index was significantly greater in progressive cirrhosis than in stable cirrhosis (P = .009). CONCLUSION: Progressive atrophy of the right hepatic lobe and the medial segment correlated with progression of clinical severity of cirrhosis, whereas increasing size of the caudate lobe and the lateral segment correlated with stability.

Adult↗
PubMed1998

Activity of respiratory pump and upper airway muscles during sleep onset.

Ventilation decreases at sleep onset. This change is initiated abruptly at alpha-theta electroencephalographic transitions. The aim of this study was to determine the contributions of reduced activity in respiratory pump muscles and upper airway dilator muscles to this change. Surface electromyograms over the diaphragm (Di) and intercostal muscles and fine-wire intramuscular electrodes in genioglossus (GG) and tensor palatini (TP) muscles were recorded in nine healthy young men. It was shown that phasic Di and both phasic and tonic TP activities were lower during theta than during alpha activity. Breath-by-breath analysis of the changes at alpha-theta transitions during the sleep-onset period showed a number of changes. At alpha-theta transitions, phasic activity of Di, intercostal, and GG muscles fell and rose again, and phasic and tonic activities of TP fell and remained at low levels during theta. With a state transition from theta to alpha, the phasic and tonic activities of the Di, GG, and TP increased dramatically. It is now clear that the fall in ventilation that occurs with sleep is related to a fall in activities of both upper airway dilator muscles and respiratory pump muscles.

Adolescent↗
PubMed1998

Prevalence of lower urinary tract symptoms in Korean men in a community-based study.

OBJECTIVE: The prevalence of lower urinary tract symptoms was determined in Korean men aged 50 and over. METHODS: A community-based, epidemiologic study was performed in Yonchon County, Korea. The Korean version of the International Prostate Symptom Score (I-PSS) was used to assess the severity of urinary symptoms in a representative sample of 514 men. RESULTS: Nocturia and weak stream were the most prevalent symptoms and urgency was the least. Overall, 23.2% of the men were moderately to severely symptomatic: 17.7% in the age group of 50-59 years, 23.3% in that of 60-69 years and 35.3% in that of 70 years and over. The proportion of severely symptomatic men approximately doubled with each decade of age. The 'quality of life' score showed a high correlation with the I-PSS. Our estimation indicated that in 1995 approximately 800,000 Korean men had moderate to severe lower urinary tract symptoms that were likely to be associated with benign prostatic hyperplasia. CONCLUSIONS: The prevalence of moderate to severe lower urinary tract symptoms in Korean men is substantially similar to that in Caucasians.

Aged↗
PubMed1998

Vascular endothelial growth factor mRNA in pericytes is upregulated by phorbol myristate acetate.

Increased microvascular permeability, which occurs in conditions such as the adult respiratory distress syndrome and diabetes mellitus, is related to physicochemical alterations in the microvascular barrier. We postulate that, in part, capillary pericytes affect microvascular permeability via production of a vasoactive cytokine, viz, vascular endothelial growth factor (VEGF), also known as vascular permeability factor. The goal of the present study was to evaluate the effects of phorbol myristate acetate (PMA), a substance known to produce nonhydrostatic pulmonary edema in intact animals, on VEGF gene expression in pericyte cultures. Microvascular pericytes were isolated from bovine retinas using magnetic microspheres coated with 3G5 monoclonal antibody. Pericyte identity was confirmed both morphologically and by immunostaining for alpha-smooth muscle actin and 3G5 ganglioside. The cultured pericytes were stimulated with N(omega)-nitro-L-arginine methyl ester (L-NAME, 1 x 10(-4) mmol/L), angiotensin II (1 x 10(-6) mmol/L), and PMA (5 x 10(-8) mmol/L), selected because of their ability to upregulate VEGF mRNA expressions in other cell types. Northern blot analysis was performed using [32P]dCTP labeled human VEGF cDNA (Genentech). Lane-loading differences were normalized using mouse GAPDH control cDNA probe. VEGF mRNA expression was upregulated by PMA (10(-9) to 10(-6) mol/L) in a dose-dependent manner, whereas neither L-NAME nor angiotensin II affected VEGF mRNA expression in pericytes. These results support the hypothesis that pericytes increase permeability of the endothelial barrier through increased VEGF production.

Angiotensin II↗
PubMed1998

Increase of mucous glycoprotein secretion by tumor necrosis factor alpha via a protein kinase C-dependent mechanism in cultured chinchilla middle ear epithelial cells.

Tumor necrosis factor alpha (TNF-alpha), originally defined by its antitumoral activity, is now recognized as a polypeptide mediator of inflammatory and cellular immune response. Recent studies have demonstrated that TNF-(alpha exists in the fluid of otitis media with effusion and, therefore, suggested its possible role in the pathogenesis of mucus hypersecretion. In this study, the effects of TNF-alpha on mucous glycoprotein (MGP) secretion from cultured chinchilla middle ear epithelial cells were examined, and TNF-alpha was found to stimulate MGP secretion in a time- and concentration-dependent manner. The action of TNF-alpha on MGP secretion was significantly and dose-dependently inhibited by TNF-alpha monoclonal antibody; this finding is suggestive of its specificity on MGP secretion. The addition of the protein kinase C inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperidine (H-7) to the culture significantly blocked TNF-alpha-induced MGP secretion, while the calmodulin inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) did not. This suggests that TNF-alpha stimulates MGP secretion via a protein kinase C-dependent mechanism.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1998

Localized form of bronchioloalveolar carcinoma: FDG PET findings.

OBJECTIVE: The aim of our study was to describe 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) findings of a localized form of bronchioloalveolar carcinoma and to compare those findings with other cell types of lung cancer. SUBJECTS AND METHODS: FDG PET was performed in 48 patients with lung cancer. The patients had carcinomas of various cell types: bronchioloalveolar carcinoma (n = 9), squamous cell carcinoma (n = 11), adenocarcinoma (n = 22), and other cell types (n = 6). Using FDG PET, we compared peak standardized uptake values among the various cell types of lung cancer. CT and pathologic findings for patients with bronchioloalveolar carcinoma were also reviewed. RESULTS: Overall, 48 malignant tumors showed a mean peak standardized uptake value of 8.0 +/- 4.1. The mean peak standardized uptake value was 3.5 +/- 2.2 for bronchioloalveolar carcinoma, 10.8 +/- 4.4 for squamous cell carcinoma, and 8.8 +/- 3.2 for adenocarcinoma. The mean peak standardized uptake value for bronchioloalveolar carcinoma was significantly lower than that for adenocarcinoma and squamous cell carcinoma (p < .001). On high-resolution CT scans, bronchioloalveolar carcinomas appeared as areas of ground-glass opacity (n = 4), as nodules (n = 2), as masses (n = 2), and as a ground-glass opacity plus consolidation (n = 1). On pathologic examination, bronchioloalveolar carcinomas were well differentiated, having moderate degrees of nuclear atypism, mild degrees of mitotic figure, desmoplasia, and necrosis. CONCLUSION: The localized form of bronchioloalveolar carcinoma shows significantly lower peak standardized uptake values than do other lung carcinomas. Thus, bronchioloalveolar carcinoma can be a potential cause of false-negative findings of malignancy on FDG PET scans. When bronchioloalveolar carcinoma is suggested, FDG PET results should be interpreted in combination with high-resolution CT findings.

Adenocarcinoma↗
PubMed1998

The history of occupational health service in Korea.

The following study was conducted to closely examine the evolution and formation of the occupational health service system in Korea during different historical periods. Korea's industrial structure has changed rapidly in the last 30 years from 1960's to 1990's, moving from a primary industry to a secondary or tertiary focused structure. Industrial accidents and occupational diseases are related closely to industrialization. Also, the new occupational health service system of each historical period has its political background. Until the mid 1980's, Korea's Occupational Health Service System was more a by-product of contemporary political, social, and economical situations rather than an effort to aggressively solve domestic industrial safety and health problems presented by laborers on the basis of academic development of industrial medicine. Therefore, the methods were to bestow a favor or one-sided. However, as Korea achieved democracy toward the end of the 1980's, it can be seen that industrial safety administration leaned toward actively dealing with the social demands of the working class.

Accidents, Occupational↗
PubMed1998

Tubulointerstitial nephritis antigen (TIN-ag) is expressed in distinct segments of the developing human nephron.

Tubulointerstitial nephritis antigen (TIN-ag) is a 58 kDa glycoprotein restricted within the kidney to basement membranes underlying the epithelium of Bowman's capsule and proximal and distal tubules. Autoantibody formation against this component has been described in association with primary immune-mediated tubulointerstital nephritis, membranous nephropathy and anti-glomerular basement membrane nephritis. In the present report, the ontogeny of this protein was studied in human fetal kidney tissue by immunohistochemical analysis of immature and developing nephrons using a panel of monoclonal and polyclonal antibodies. TIN-ag is first detected in basement membranes underlying the epithelium of Bowman's capsule of early capillary loop stage glomeruli and the primitive proximal tubule. No detectable expression is observed in the basement membranes of the branching ureteric bud, nephrogenic vesicle, or comma shape and s-shape stages of nephrogenic development. Increased staining of the proximal tubular basement membrane is associated with outgrowth of the primitive tubule from the urinary pole of the developing glomerulus. In more mature fetal tubules, TIN-ag expression closely resembles that of previously reported observations in mature tissue where it is present in high amounts in the basement membranes of proximal tubules, and to a lesser extent in Bowman's capsule and distal tubules. Our results suggest that TIN-ag expression is developmentally regulated in a precise spatial and temporal pattern throughout nephrogenesis.

Antibodies, Monoclonal↗
PubMed1998

Adhesion of cultured human kidney mesangial cells to native entactin: role of integrin receptors.

Entactin is an extracellular matrix glycoprotein which binds to laminin and is found in most renal basement membranes and in the glomerular mesangial matrix. In the present study, we have characterized specific integrin receptors on cultured human mesangial cells (CHMC) responsible for adhesion to native entactin. The integrin receptors alpha 2 beta 1, alpha 3 beta 1, alpha 5 beta 1, alpha v beta 3, alpha v beta 5, and alpha 6 complexed with either beta 1 or beta 4 could be immune precipitated from detergent extracts of metabolically labeled CHMC. Adhesion assays with inhibitory anti integrin monoclonal antibodies (mab) demonstrated that CHMC use both alpha v beta 3 and a beta 1-containing integrin to bind surfaces coated with native entactin. Optimal binding of CHMC to native entactin required the participation of cations. Using wild type and mutant recombinant entactin fragments, the binding site for the alpha v beta 3 receptor was localized to the RGD sequence on the rod or E domain of entactin. CHMC adhesion to mutant full length recombinant entactin ligands lacking the E domain RGD sequence confirmed the presence of ligand binding site(s) for beta 1 integrin receptor(s). Differences in CHMC binding characteristics to recombinant and full length entactin compared to native bovine basement membrane entactin were observed. This suggests that tertiary molecular structure may contribute to entactin ligand binding properties. Primary amino acid residue sequences and tertiary structure of entactin may play roles in forming functional cell attachment sites in native basement membrane entactin.

Animals↗
PubMed1998

Manganese induced parkinsonism: a case report.

Manganese (Mn) intoxication is known to induce parkinsonism. Mn-induced parkinsonism preferentially affect the globus pallidus in contrast to idiopathic parkinsonism where degeneration predominantly involves the nigral pars compacta. We describe a 51-year-old man who had been occupationally exposed to Mn. He had parkinsonian features including masked face, resting tremor, and bradykinesia. He also had a cock walk and a particular propensity to fall in a backward gait. There was no sustained therapeutic response to levodopa. A fluorodopa PET scan was normal. This case indicates that Mn-induced parkinsonism can be differentiated from idiopathic parkinsonism in that the former has unique clinical features and a normal fluorodopa PET scan.

Humans↗
PubMed1998

Physical properties of resin-modified glass-ionomers.

The physical properties and shear bond strength of two resin-modified glass-ionomers: RMGIs (FJL and VT) and as a control, a conventional glass-ionomer: CGI (FJ), were evaluated. Ninety percent of the setting shrinkage under dry conditions and nominal hygroscopic expansion in water during 360 h occurred within the first 24 h. The nominal hygroscopic expansion of CGI was 0.38% while the RMGIs demonstrated over 1%, but considering the setting shrinkage the total hygroscopic expansion of CGI and the RMGIs were over 7 times and about 2.5 times, respectively. The thermal expansion of the RMGIs after water immersion was greater than that under dry condition. In contrast, FJ demonstrated expansion less than under dry condition. There was no significant difference between FJL and VT (P < 0.05) as regard water absorption. The shear bond strength of the RMGIs to enamel and dentin were superior to FJ, except for VT to dentin.

Absorption↗
PubMed1998

Furcation involvements: therapeutic considerations.

The successful treatment of furcation-involved multirooted teeth has been a challenge for many clinicians. Furcation lesions have been treated by osseous resection, root amputation, tooth hemisection, and other methods. Recently, guided tissue regeneration has been considered the treatment of choice, but inconsistent treatment outcomes have caused frustration for many clinicians. This article discusses the complexity of the furcation lesion, important aspects of the lesion and its relation to the tooth anatomy, and treatment options that should be considered.

Dental Implants↗