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Biomedical subjects

W Y Kim

Publications and source records attributed to W Y Kim.

At least 37 records · Page 2Linked to original sources
PubMed2001

Electromechanical mapping for detection of myocardial viability in patients with ischemic cardiomyopathy.

BACKGROUND: We evaluated the ability of electromechanical mapping of the left ventricle to distinguish between nonviable and viable myocardium in patients with ischemic cardiomyopathy. METHODS AND RESULTS: Unipolar voltage amplitudes and local endocardial shortening were measured in 31 patients (mean+/-SD age, 62+/-8 years) with ischemic cardiomyopathy (ejection fraction, 30+/-9%). Dysfunctional regions, identified by 3D echocardiography, were characterized as nonviable when PET revealed matched reduction of perfusion and metabolism and as viable when perfusion was reduced or normal and metabolism was preserved. Mean unipolar voltage amplitudes and local shortening differed among normal, nonviable, and viable dysfunctional segments. Coefficient of variation for local shortening exceeded differences between groups and did not allow distinction between normal and dysfunctional myocardium. Optimum nominal discriminatory unipolar voltage amplitude between nonviable and viable dysfunctional myocardium was 6.5 mV, but we observed a great overlap between groups. Individual cutoff levels calculated as a percentage of electrical activity in normal segments were more accurate in the detection of viable dysfunctional myocardium than a general nominal cutoff level. The optimum normalized discriminatory value was 68%. Sensitivity and specificity were 78% for the normalized discriminatory value compared with 69% for the nominal value (P:<0.02). CONCLUSIONS: Endocardial ECG amplitudes in patients with ischemic cardiomyopathy display a wide scatter, complicating the establishment of exact nominal values that allow distinction between viable and nonviable areas. Individual normalization of unipolar voltage amplitudes improves diagnostic accuracy. Electroanatomic mapping may enable identification of myocardial viability.

Body Surface Potential Mapping↗
PubMed2001

Impact of bulk cardiac motion on right coronary MR angiography and vessel wall imaging.

The purpose of this study was to investigate the impact of in-plane coronary artery motion on coronary magnetic resonance angiography (MRA) and coronary MR vessel wall imaging. Free-breathing, navigator-gated, 3D-segmented k-space turbo field echo ((TFE)/echo-planar imaging (EPI)) coronary MRA and 2D fast spin-echo coronary vessel wall imaging of the right coronary artery (RCA) were performed in 15 healthy adult subjects. Images were acquired at two different diastolic time periods in each subject: 1) during a subject-specific diastasis period (in-plane velocity <4 cm/second) identified from analysis of in-plane coronary artery motion, and 2) using a diastolic trigger delay based on a previously implemented heart-rate-dependent empirical formula. RCA vessel wall imaging was only feasible with subject-specific middiastolic acquisition, while the coronary wall could not be identified with the heart-rate-dependent formula. For coronary MRA, RCA border definition was improved by 13% (P < 0.001) with the use of subject-specific trigger delay (vs. heart-rate-dependent delay). Subject-specific middiastolic image acquisition improves 3D TFE/EPI coronary MRA, and is critical for RCA vessel wall imaging.

Adult↗
PubMed2001

3D coronary vessel wall imaging utilizing a local inversion technique with spiral image acquisition.

Current 2D black blood coronary vessel wall imaging suffers from a relatively limited coverage of the coronary artery tree. Hence, a 3D approach facilitating more extensive coverage would be desirable. The straightforward combination of a 3D-acquisition technique together with a dual inversion prepulse can decrease the effectiveness of the black blood preparation. To minimize artifacts from insufficiently suppressed blood signal of the nearby blood pools, and to reduce residual respiratory motion artifacts from the chest wall, a novel local inversion technique was implemented. The combination of a nonselective inversion prepulse with a 2D selective local inversion prepulse allowed for suppression of unwanted signal outside a user-defined region of interest. Among 10 subjects evaluated using a 3D-spiral readout, the local inversion pulse effectively suppressed signal from ventricular blood, myocardium, and chest wall tissue in all cases. The coronary vessel wall could be visualized within the entire imaging volume.

Adult↗
PubMed2001

Failure of intertrochanteric fracture fixation with a dynamic hip screw in relation to pre-operative fracture stability and osteoporosis.

We have reviewed 178 intertrochanteric fractures treated by dynamic hip screw (DHS) fixation between March 1995 and December 1999 and followed for a minimum of 1 year. We used Singh's classification of the trabecular bone structure in the proximal femur as a measure of osteoporosis and also classified the fractures according to three different systems (Boyd-Griffin, Evans, AO). The postoperative radiographs were examined for loss of reduction, i.e. varus angulation >100, perforation of the femoral head, more than 20-mm extrusion of a lag screw or metal failure. We found 49 cases which showed radiographic failures. Two were stable fractures and 47 unstable fractures (Evans' classification). Unstable fractures with osteoporosis had a failure rate of more than 50%. In such cases DHS should not be the first choice for treatment.

Aged↗
PubMed2001

BCG infection in allergen-presensitized rats suppresses Th2 immune response and prevents the development of allergic asthmatic reaction.

Recent investigations demonstrate that bacille Calmette-Guerin (BCG), a potent inducer of Th1 response, infection prior to allergen sensitization inhibits Th2 immune responses to the allergen. However, it is not clear whether BCG infection in allergen-presensitized rats switches off Th2 response and prevents allergic asthmatic reaction to the subsequent allergen exposure. In this study we investigate whether BCG infection in ovalbumin (OVA)-presensitized Sprague-Dawley rats suppresses airway hyperresponsiveness and eosinophilic inflammation induced by OVA and Th2 cytokine production. BCG infection in OVA-presensitized rats significantly inhibited not only the sensitivity of airway smooth muscle to electrical field stimulation and acetylcholine but also absolute eosinophil counts in bronchoalveolar lavage fluid. As a correlate, interleukin-4 (IL-4) production significantly decreased and interferon-gamma (IFN-gamma) slightly increased, resulting in a markedly decreased ratio of IL-4-IFN-gamma in OVA-presensitized rats with BCG infection. These results indicate that BCG infection in pre-sensitized rats suppresses allergic asthmatic reaction and Th2 immune response. It is possible from these findings that BCG vaccine may be used as an immunomodulating agent for the sensitized host with preestablished Th2 memory.

Allergens↗
PubMed2001

Selection of a potential probiotic Lactobacillus strain and subsequent in vivo studies.

The probiotic potential of a Lactobacillus strain, isolated from pig faeces, was assessed as a probiotic in piglets. The strain was examined for resistance to pH 2.0, 0.5% oxgall and antibiotics, and antimicrobial activities against enteric pathogenic bacteria. The probiotic strain, L. reuteri BSA131, was administered through the feed to 25 1-month-old Landrace piglets. The piglets were divided into five groups of five piglets each and fed with different diets for 28 days. The daily consumption of L. reuteri BSA131 was assigned into two groups by the concentration of 10(6) or 10(8) freeze-dried bacteria. Fecal samples were collected before, during, and after consumption. Lactobacilli and enterobacteria cell counts were determined in the fecal samples. The liveweight gains and feed consumption of the piglets were recorded daily. This study showed that strain BSA131 enhanced liveweight gains and feed conversion rates in piglets. It also showed a significant increase in lactobacilli cell counts and decreases in enterobacterial numbers in the fecal samples. Strain BSA131 was considered to be a potential probiotic for piglets, especially after weaning.

Animal Feed↗
PubMed2001

Influence of the renin-angiotensin system on epidermal growth factor expression in normal and cyclosporine-treated rat kidney.

BACKGROUND: Epidermal growth factor (EGF) plays an important role in renal tubular regeneration after ischemic injury in kidney. The present study reports the association between the renin-angiotensin system (RAS) and EGF, and the effect of angiotensin II blockade with losartan (LSRT) on EGF expression in an experimental model of chronic cyclosporine (CsA) nephrotoxicity in rats. METHODS: Two separate experiments were performed. In the first experiment, rats on the normal-salt diet (NSD; 0.3%) or low-salt diet (LSD; 0.05%) were treated with or without LSRT for four weeks. In the second experiment, rats on the NSD or LSD were given vehicle (VH group, olive oil, 1 mg/kg per day) or CsA (15 mg/kg per day) or CsA (15 mg/kg per day) plus LSRT (100 mg/L per day). Renal function, histopathology, TUNEL staining, plasma renin activity (PRA), and the expression of renin and EGF were studied. RESULTS: Normal rats on the LSD showed significantly increased EGF expression (cortex, 2.6-fold; medulla, 1.7-fold) and significantly decreased EGF expression with the LSRT treatment compared with the rats treated with the NSD (cortex, 74.8 vs. 10%; medulla, 22.5 vs. 5%). In contrast, the CsA-treated rats on the LSD had a significantly lower EGF expression (cortex, 98 vs. 53%; medulla, 94 vs. 14%); however, concomitant administration of LSRT increased the EGF expression (cortex, 91- vs. 3.8-fold; medulla, 19- vs. 2.4-fold) compared with the rats on the NSD. In the normal and CsA-treated LSD rats, EGF expression was well correlated with PRA. In addition, EGF expression was well correlated with the interstitial fibrosis score (r = 0.664, P < 0.01) or number of TUNEL-positive cells (r = 0.822, P < 0.01) in CsA-treated LSD rats. CONCLUSIONS: These results suggest that angiotensin II blockade with LSRT decreases EGF expression in normal rats on the LSD, but it protects EGF expression in CsA-induced nephrotoxicity. This finding provides a new perspective on the renoprotection of angiotensin II blockade in chronic CsA nephrotoxicity.

Angiotensin II↗
PubMed2001

Measurement of left ventricular volumes by 3-dimensional echocardiography with tissue harmonic imaging: a comparison with magnetic resonance imaging.

We hypothesized that tissue harmonic imaging (THI) in comparison with fundamental imaging (FI) would improve endocardial border detection, and therefore in combination with 3-dimensional echocardiography (3D echo), it would be a precise method for left ventricular (LV) volume measurement. Ten healthy subjects and 18 consecutive patients with dilated hearts underwent estimation of LV volumes by magnetic resonance imaging (MRI) and transthoracic 3D echo with THI and FI. In patients, the agreement between MRI and 3D echo was closer with THI in comparison with FI for assessment of LV volumes. Thus the mean +/- 2 SD of differences between MRI and 3D echo with THI versus FI, respectively, was -6.4 +/- 40.0 mL versus -17.4 +/- 57.6 mL (P <.01) for the end-diastolic volume (EDV), and 0.0 +/- 26.6 mL versus -8.1 +/- 35.6 mL (P <.01) for the end-systolic volume (ESV). In patients, THI in comparison with FI approximately halved observer variation on EDV and ESV. In healthy subjects, only ESV showed significantly reduced observer variation by THI. In conclusion, because THI demonstrated a clinically relevant reduction in observer variation and a closer agreement to the MRI technique in patients with dilated hearts, it should replace FI in LV volume measurements.

Adult↗
PubMed2001

Three-dimensional echocardiography with tissue harmonic imaging shows excellent reproducibility in assessment of left ventricular volumes.

We studied the reproducibility of repeated measurements of left ventricular (LV) volumes by 2-dimensional (biplane method of disks) and 3-dimensional echocardiography (coaxial scanning) with tissue harmonic imaging. Ten healthy subjects underwent estimation of LV volumes by transthoracic echocardiography twice within 1 week by 2 different operators to investigate interexamination and operator variance. In addition, the analysis of LV volume was done manually by 2 observers to assess both interobserver and intraobserver variances. With 3D echocardiography, observer variation had the greatest impact on variance. Operator variability showed important contributions to total variance with the use of 2D echocardiography. The reproducibility of 3D echocardiography and tissue harmonic imaging is excellent and comparable to magnetic resonance imaging techniques; 3D echocardiography therefore should provide a powerful tool for noninvasive LV volume estimation.

Adult↗
PubMed2001

Glucocorticoid-mediated repression of inflammatory cytokine production in fibroblast-like rheumatoid synoviocytes is independent of nuclear factor-kappaB activation induced by tumour necrosis factor alpha.

OBJECTIVE: To determine whether steroids inhibit the production of inflammatory cytokines by the inhibition of nuclear factor kappaB (NF-kappaB) activation in fibroblast-like rheumatoid synoviocytes (FLSs) under inflammatory conditions, and to determine whether steroids stimulate the induction of synthesis of the inhibitory protein IkappaB-alpha in the anti-inflammatory immune response of these cells. METHODS: Expression of the interleukin-6 (IL-6) and interleukin-1beta (IL-1beta) genes was measured by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), and the secreted IL-6 was measured with the enzyme-linked immunosorbent assay. Inhibition of the NF-kappaB activation was examined with the electrophoretic mobility shift assay (EMSA). In order to study dexamethasone (DEX)-dependent regulation of IkappaB-alpha expression, we performed Western blotting before and after stimulation with tumour necrosis factor alpha (TNF-alpha). RESULTS: The inflammatory cytokine study showed that DEX suppressed gene expression and the production of protein in FLSs. EMSA demonstrated that identical amounts of NF-kappaB were present in the nucleus of the FLSs stimulated by TNF-alpha, with or without pretreatment with DEX. Treatment of FLSs with DEX did not induce an increase in IkappaB-alpha sufficient to prevent nuclear translocation of NF-kappaB on stimulation with TNF-alpha. CONCLUSION: DEX may suppress the production of inflammatory cytokines, such as IL-6 and IL-1beta, but it neither prevents the translocation of NF-kappaB to the nucleus nor induces the synthesis of IkappaB-alpha protein in FLSs stimulated by TNF-alpha.

Arthritis, Rheumatoid↗
PubMed2001

Bowel herniation after traumatic symphysis pubis diastasis.

The authors describe a patient with small bowel herniation after traumatic symphysis disruption. Although gastrointestinal problems occur rarely with pelvic fractures, in a patient with a pubic diastasis and paralytic ileus, the development of abdominal hernia through torn peritoneum should be considered. Treatment of the patient with a pubic diastasis and a bowel problem should include early careful exploration and management of the gastrointestinal tract during pelvic surgery.

Accidental Falls↗
PubMed2001

Three dimensional echocardiography documents haemodynamic improvement by biventricular pacing in patients with severe heart failure.

OBJECTIVES: To quantify the short term haemodynamic effects of biventricular pacing in patients with heart failure and left bundle branch block by using three dimensional echocardiography. DESIGN: Three dimensional echocardiography was performed in 15 consecutive heart failure patients (New York Heart Association functional class III or IV) with an implanted biventricular pacing system. Six minute walk tests were performed to investigate the effect of biventricular pacing on exercise capacity. Data were acquired at sinus rhythm and after short term (2-7 days) biventricular pacing. RESULTS: Compared with baseline values, biventricular pacing significantly reduced left ventricular end diastolic volume (EDV) by mean (SD) 4.0 (5.1)% (p < 0.01) and end systolic volume (ESV) by 5.6 (6.4)% (p < 0.02). Mitral regurgitant fraction was significantly reduced by 11 (12.1)% (p < 0.003) and forward stroke volume (FSV) increased by 13.9 (18.6)% (p < 0.02). Exercise capacity was significantly improved with biventricular pacing by 48.4 (43.3)% (p < 0.00001). Regression analyses showed that the percentage increase in FSV independently predicted percentage improvement in walking distance (r(2) = 0.73, p < 0.0002). Both basal QRS duration and QRS narrowing predicted pacing efficacy, showing a significant correlation with %DeltaEDV, %DeltaESV, and %DeltaFSV. CONCLUSIONS: In five of 15 consecutive patients with heart failure and left bundle branch block, biventricular pacing induced a more than 15% increase in FSV, which predicted a more than 25% increase in walking distance and was accompanied by an immediate reduction in left ventricular chamber size and mitral regurgitation.

Adult↗
PubMed2001

Impact of acute biventricular pacing on left ventricular performance and volumes in patients with severe heart failure. A tissue doppler and three-dimensional echocardiographic study.

OBJECTIVES: We used tissue velocity imaging (TVI) and three-dimensional echocardiography to evaluate the effect of acute biventricular pacing on left ventricular (LV) performance and volumes in patients with severe heart failure and bundle branch block. BACKGROUND: Biventricular pacing causes acute hemodynamic improvement in patients with severe heart failure, and QRS duration has been used as a predictor of improved resynchronization. Tissue velocity has the potential of demonstrating the degree of LV resynchronization and three-dimensional echocardiography enables accurate quantitation of LV volumes and function. METHODS: TVI and three-dimensional echocardiography were performed during sinus rhythm and biventricular pacing in 25 consecutive patients with severe heart failure. RESULTS: Biventricular pacing significantly improved the extent of contracting myocardium in synchrony by 15.4% and the duration of contraction synchrony by 17% (p < 0.05 for both). Furthermore, end-diastolic and end-systolic volumes decreased by 7 +/- 4.5% and 13 +/- 6% (p < 0.01) and ejection fraction increased by 22.8 +/- 9% (p < 0.01). Baseline duration of QRS and the preejection period as well as the extent of myocardium with asynchronous contraction measured by TVI predicted pacing efficacy. In multivariate analysis, only the extent of myocardium with asynchronous contraction at the LV base predicted biventricular pacing efficacy. CONCLUSION: Biventricular pacing improves LV systolic performance and reduces LV volumes during short-term treatment. TVI provides important pathophysiological information on the degree of LV resynchronization and may contribute to improved patient selection.

Bundle-Branch Block↗
PubMed2001

NeuroD-null mice are deaf due to a severe loss of the inner ear sensory neurons during development.

A key factor in the genetically programmed development of the nervous system is the death of massive numbers of neurons. Therefore, genetic mechanisms governing cell survival are of fundamental importance to developmental neuroscience. We report that inner ear sensory neurons are dependent on a basic helix-loop-helix transcription factor called NeuroD for survival during differentiation. Mice lacking NeuroD protein exhibit no auditory evoked potentials, reflecting a profound deafness. DiI fiber staining, immunostaining and cell death assays reveal that the deafness is due to the failure of inner ear sensory neuron survival during development. The affected inner ear sensory neurons fail to express neurotrophin receptors, TrkB and TrkC, suggesting that the ability of NeuroD to support neuronal survival may be directly mediated through regulation of responsiveness to the neurotrophins.

Animals↗
PubMed2001

Effects of BCG infection on Schultz-Dale reaction, allergen-specific IgE levels, and Th2 immune response in sensitized rats.

BACKGROUND: BCG, a potent inducer of Th1 immune response, has been suggested to suppress Th2 response which is known to mediate IgE-mediated allergic disorders, in particular allergic asthma. Schultz-Dale reaction is known to be a model of IgE-mediated hypersensitivity. This study was done to investigate whether BCG infection suppresses the Schultz-Dale reaction by inhibiting Th2 response and allergen-specific IgE production. METHODS: Twenty-four Sprague-Dawley rats were sensitized and provoked with ovalbumin (OVA). A pretreatment of 6 x 10(4) colony forming units of BCG or saline was done 7 days before sensitization. The Schultz-Dale reaction was represented as tracheal smooth muscle contractions to 50 micrograms/mL OVA challenge in vitro. Serum OVA-specific IgE levels and IFN-gamma and IL-4 concentrations in bronchoalveolar lavage fluid (BALF) were measured. RESULTS: The Schultz-Dale reaction and serum OVA-specific IgE levels were significantly decreased in BCG infected and OVA sensitized rats compared with only sensitized rats (p < 0.01 and p < 0.05, respectively). As compared with only sensitized rats, IL-4 concentration and a ratio of IFN-gamma:IL-4 in BCG infected and OVA sensitized rats were significantly decreased (p < 0.001) and increased (p < 0.05), respectively. The Schultz-Dale reaction was correlated with OVA-specific IgE levels (r = 0.50, p < 0.05), IL-4 concentration (r = 0.69, p < 0.001), and ratio of IFN-:IL-4 (r = -0.44, p < 0.05). OVA-specific IgE levels were correlated with IL-4 concentration (r = 0.61, p < 0.01) and ratio of IFN-gamma:IL-4 (r = -0.48, p < 0.05). CONCLUSION: These findings suggest that BCG infection prior to allergen sensitization may inhibit Schultz-Dale reaction developed in the sensitized rat tracheal smooth muscle via the suppressive effects of Th2 immune response and allergen-specific IgE production.

Animals↗
PubMed2000

Noninvasive coronary vessel wall and plaque imaging with magnetic resonance imaging.

BACKGROUND: Conventional x-ray angiography frequently underestimates the true burden of atherosclerosis. Although intravascular ultrasound allows for imaging of coronary plaque, this invasive technique is inappropriate for screening or serial examinations. We therefore sought to develop a noninvasive free-breathing MR technique for coronary vessel wall imaging. We hypothesized that such an approach would allow for in vivo imaging of coronary atherosclerosis. METHODS AND RESULTS: Ten subjects, including 5 healthy adult volunteers (aged 35+/-17 years, range 19 to 56 years) and 5 patients (aged 60+/-4 years, range 56 to 66 years) with x-ray-confirmed coronary artery disease (CAD), were studied with a T2-weighted, dual-inversion, fast spin-echo MR sequence. Multiple adjacent 5-mm cross-sectional images of the proximal right coronary artery were obtained with an in-plane resolution of 0.5x1.0 mm. A right hemidiaphragmatic navigator was used to facilitate free-breathing MR acquisition. Coronary vessel wall images were readily acquired in all subjects. Both coronary vessel wall thickness (1.5+/-0.2 versus 1.0+/-0.2 mm) and wall area (21.2+/-3.1 versus 13.7+/-4.2 mm(2)) were greater in patients with CAD (both P:<0.02 versus healthy adults). CONCLUSIONS: In vivo free-breathing coronary vessel wall and plaque imaging with MR has been successfully implemented in humans. Coronary wall thickness and wall area were significantly greater in patients with angiographic CAD. The presented technique may have potential applications in patients with known or suspected atherosclerotic CAD or for serial evaluation after pharmacological intervention.

Adipose Tissue↗
PubMed2000

Luminescent ruthenium(II) bipyridyl-phosphonic acid complexes: pH dependent photophysical behavior and quenching with divalent metal ions.

The synthesis, redox behavior, and photophysical properties of a series of Ru(II) bipyridyl complexes having diimine ligands with phosphonate and phosphonic acid substituents are presented. The phosphonate-containing ligands examined include diethyl 4-(2,2'-bipyrid-4-yl)benzylphosphonate (bpbzp), diethyl 4-(2,2'-bipyrid-4-yl)-phenylphosphonate (bppp), and 4,4'-(diethyl phosphonato)-2,2'-bipyridine (bpdp), and the [(bpy)2Ru(L)](PF6)2 complexes of both the diethyl phosphonate and the phosphonic acid were prepared. The Ru(III/II) potentials are more positive for the phosphonate complexes than for the phosphonic acids, and the first reduction is localized on the phosphonate-containing ligand for the bppp and bpdp complexes. The first reduction of the phosphonic acid complexes is at more negative potentials and cannot be distinguished from bpy reduction. For the bppp and bpdp complexes luminescence arises from a Ru(d pi)-->bpy-phosphonate (pi*) MLCT state; the phosphonic acid complexes luminescence at higher energies from a MLCT state not clearly isolated on one ligand. Iron(III) and copper(II) complex with and very efficiently quench the luminescence of all the phosphonic acid complexes in nonaqueous solvents. The quenching mechanism is discussed on the basis of luminescence decay and picosecond transient absorption measurements.

Journal Article↗