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Biomedical subjects

S H Cho

Publications and source records attributed to S H Cho.

At least 217 records · Page 12Linked to original sources
PubMed1987

Alterations of the myocardial skeletal framework in acute myocardial infarction with and without ventricular rupture. A preliminary report.

Thinning and dilatation (expansion) of the infarct region and complete rupture of the ventricular wall are significant complications of acute transmural myocardial infarction associated with increased morbidity and mortality. The pathogenesis of these related events is unknown. Recent studies of myocardial connective tissue have delineated an extensive array of intercellular and pericellular structures which serve as a skeletal framework and which may modulate contractile activity. We have employed a modified silver impregnation method to visualize the connective tissue components by light microscopy. To explore whether the skeletal framework is altered in acute myocardial infarction with and without ventricular rupture, we studied 9 human hearts at autopsy, and 4 canine infarcts of known duration. The human infarctions included 4 nonruptured cases with infarcts 1-5 days old, and 5 ruptured cases with infarcts 3-10 days old. Sections from normal, lateral, and central infarct or ventricular rupture sites were stained with silver. The normal tissue from each heart served as a control. Silver staining was moderately decreased in the lateral infarct zones, and markedly decreased in the central non-ruptured infarct zones. In the 5 ventricular rupture cases, the rupture site had no silver staining. A similar pattern was observed in the 4 canine infarcts. Thus, we conclude that the skeletal framework is markedly altered in the central zone of acute myocardial infarction. The acute changes of silver stained connective tissue may contribute significantly to the development of infarct expansion or ventricular wall rupture.

Animals↗
PubMed1985

Isolation and quantitative analysis of phosphatidylglycerol and glycolipid molecular species using reversed-phase high-performance liquid chromatography with flame ionization detection.

Conditions are described for the quantitative analysis of phosphatidylglycerol and plant glycolipid molecular species by reversed-phase high-performance liquid chromatography employing a commercially available flame ionization detector. Direct detection on a mass basis overcomes the problem of poor detectability found with most natural lipids. Effective mobile phases composed primarily of volatile solvents are described. Splitting of the column eluate stream allows a portion of each individual molecular species to be recovered for other types of analysis.

Chromatography, Gas↗
PubMed1982

Model for cooperativity of biological membranes.

We present a mathematical model for the complex cooperativity observed in biological membranes. In our model, it is assumed that the proteins bound on the membrane are noncooperative and possess a Bohr proton. It is further assumed that the net charge of the unliganded state of the protein is different from that of the liganded state owing to the structural change upon binding the ligand. With this model, we show how an all-or-none response, a graded response, and a noncooperative response arise in the binding curve of such biological membranes. In addition, we show how an effector, which can alter the pKa involved in the binding site, induces a complex cooperativity.

Ligands↗
PubMed1982

On exploring the basis for slow and fast oscillations in cellular systems.

We show that interesting oscillatory patterns may arise from an immobilized enzyme system, when the enzyme has the properties that it is inhibited by a substrate, produces H+ and has a pH-activity curve of bell-shaped form. In agreement with experimental observations in cellular excitations, the system generates fast oscillations that are superimposed on a slow cycle, at certain salt and enzyme concentrations.

Animals↗
PubMedDate not supplied

Effects of platelet-derived growth factor-AA on the healing process of tympanic membrane perforation.

PURPOSE: Platelet-derived growth factor basic 30-kD disulfide-bonded dimer of A and B chains (PDGF-AA, PDGF AB, PDGF-BB) and a cytokine, promoting wound healing by its mitogenicity for fibroblast and by stimulating the production of fibronectin and hyaluronic acid. This article investigates the effect of PDGF on the healing process of tympanic membrane (TM) perforation. MATERIALS AND METHODS: The pars tensa of the posterior aspect of the TM of rats was excised and treated with 2 microg of PDGF-AA or placebo. The animals were killed at 3, 5, 7, 9, 11, 15, and 28 days after operation. The healing process of TM perforation was observed with a telescope and light microscope. The temporal bones were also immunohistochemically examined for PDGF-alpha receptor (PDGF-R(alpha)) and fibronectin. RESULTS: All PDGF-AA-treated TM were completely closed by 5 days after surgery, whereas some of the placebo-treated TM were not closed at 15 postoperative days. PDGF-AA induced the most prominent proliferation of the connective tissue by 9 postoperative days, after which the growth of the connective tissue decreased. By the 4th postoperative week, the PDGF-treated TM were slightly thicker than normal TM. An intense expression of fibronectin was detected in the connective tissue layer of the TM that were treated with PDGF-AA. PDGF-R(alpha) was expressed in the epithelial layer of both the PDGF-treated and control TM. CONCLUSION: These results show that PDGF-AA speeds up the healing process of TM defect, improves the rate of healing, and prevents atrophic changes in the healed TM by promoting the connective tissue growth. The use of PDGF-AA can be an effective alternative to surgery for managing TM perforations.

Animals↗
PubMedDate not supplied

Solitary giant molluscum contagiosum of the sole.

Molluscum contagiosum of the sole is extremely rare and only three cases have been reported in the literature. We report a solitary giant molluscum contagiosum on the left sole of a 5-year-old boy, which should be clinically differentiated from plantar wart, eccrine poroma, epidermal cyst, foreign body granuloma, cryptococcal infection, and pyogenic granuloma.

Biopsy, Needle↗
PubMedDate not supplied

Congenital linear steatocystoma multiplex of the nose.

We describe a case of steatocystoma multiplex with an unusual clinical manifestation. A 5-year-old girl had 8 papulonodular lesions arranged in a linear fashion on the left side of the nose. These had been present at birth. Histologically the lesions showed the typical features of steatocystoma multiplex. There was no family history of similar lesions. This is the second case of linear steatocystoma multiplex, a rare variant of steatocystoma multiplex.

Child, Preschool↗
PubMedDate not supplied

Formaldehyde exposure levels and serum antibodies to formaldehyde-human serum albumin of Korean medical students.

In our study, we estimated formaldehyde exposure levels of Korean medical students during their cadaver dissection practice hours. In addition, we examined the prevalence rates of formaldehyde-specific immunoglobulin E or immunoglobulin G antibodies and compared the results with the symptoms the students experienced as a result of formaldehyde exposure. There were 167 Korean medical students (i.e., subjects) aged 23.8+/-2.5 y (mean+/-standard deviation) and a control group of 67 premedical students aged 20.1+/-2.8 y (mean+/-standard deviation). Concentrations of formaldehyde in the cadaver dissection practice laboratory ranged from 0.194 to 11.245 mg/m3 (3.736+/-3.478 mg/m3 [mean+/-standard deviation]). Students reported by self-administered questionnaires that eye soreness (92.8%) and lacrimation (74.9%) were the most common symptoms they experienced during the laboratory sessions. One (0.6%) of the 167 medical students had a history of wheezing during dissection. Fourteen (8.4%) had specific immunoglobulin G antibody, but none had specific immunoglobulin E antibody. These results suggest that (a) Korean medical students are exposed to formaldehyde at a relatively high levels in their dissection practice hours, (b) specific immunoglobulin G is not related to adverse eye or respiratory symptoms, and (c) specific immunoglobulin E is rarely induced as a result of exposure to formaldehyde.

Antibodies↗
PubMedDate not supplied

Microencapsulation of lipid nanoparticles containing lipophilic drug.

A polymeric emulsion bead, which consists of core and capsule, was prepared. The core is composed of lipid nanoparticles containing lipophilic drug and semi-interpenetrating networks (semi-IPNs) are prepared to provide the capsule composed of sodium alginate and hydroxypropylmethyl cellulose (HPMC). The lipid nanoparticles were encapsulated into the polymeric emulsion bead with high drug loading efficiency, and lovastatin was used as a model drug. For the application as an oral drug delivery system, the enteric coating was performed with polymeric emulsion bead. The drug release pattern was controlled by the composition of capsule materials and environmental pH.

Administration, Oral↗
PubMedDate not supplied

Relationship between lateral subluxation and widening of medial joint space in Legg-Calvé-Perthes disease.

Fifty-five patients (61 affected hips and 49 unaffected hips) with Perthes disease were reviewed to evaluate the relationship between widening of medial joint space and lateral subluxation of the femoral head in radiographs. The components of the medial joint space were evaluated by using T1, T2, proton, and Gd-enhanced T1WI magnetic resonance images (MRI). The widened medial joint space in radiographs was filled with overgrown cartilage at the initial stage (27 hips) in MRI, with both overgrown cartilage and widened true medial joint space at the fragmentation stage (23 hips) and widened true medial joint space at the healing stage (11 hips). Between affected hips and unaffected hips, the mean difference of medial joint space in radiographs between hips at the initial stage and at the fragmentation stage was 2 and 4.5 mm, respectively; the mean difference in percentage of lack of coverage of the femoral head between hips at the initial stage and at the fragmentation stage was 3 and 15%, respectively. During the healing stage, widening of the medial joint space decreased or normalized because of ossification of overgrown cartilage despite the existence of lateral subluxation because of coxa magna. We concluded that widening of the medial joint space may be used as an index of lateral subluxation at only the fragmentation stage in Perthes disease.

Adolescent↗
PubMedDate not supplied

Classification of metaphyseal change with magnetic resonance imaging in Legg-Calvé-Perthes disease.

Seventy-eight patients (85 affected hips and 71 unaffected hips) with Legg-Calvé-Perthes disease were included in this study to evaluate the metaphyseal change in radiographs and magnetic resonance imaging (MRI) and to define the type of the metaphyseal cyst according to presence or absence of the epiphyseal involvement. The content of the metaphyseal cyst was evaluated by using T1,T2, proton, and gadolinium-enhanced T1-weighted MRI scans. Among 85 hips, there were no changes in 32 hips, marrow edema in 13 hips, false cyst with epiphyseal involvement in 28 hips, and true cyst without epiphyseal involvement in 12 hips. Granulation tissue was found in the false cysts and water-rich fibrotic tissue was found in the true cysts based on the MRI scans. The metaphyseal change in MRI scans was shown in 71% of groups 3 and 4 and in 35% of groups 1 and 2 according to the Catterall classification, and 52% of group A, 56% of group B, and 86% of group C according to the Herring classification. Of the 30 hips at the avascular stage, 33% showed metaphyseal cyst in MRI scans. Of the 53 hips at the fragmentation stage, 60% showed the metaphyseal cyst.

Adolescent↗