Biomedical subjects

S H Choi

Publications and source records attributed to S H Choi.

At least 91 records · Page 5Linked to original sources

PubMed2001

Effects of pretreatment clinical parameters on bioactive glass implantation in intrabony periodontal defects.

BACKGROUND: The various methods for regeneration of periodontal tissue that have been developed can be classified into guided tissue regeneration and bone implantation. Since the implantation materials have shown both deficiencies and merits, dentists have begun exploring the bioactive glass first used in plastic surgery. This paper examines the effectiveness of this new material on periodontal intrabony defects. METHODS: Clinical effects of bioactive glass implantation in intrabony periodontal defects were evaluated 6 months after surgery in 38 intrabony defects from 38 patients with chronic periodontitis. Twenty-one experimental defects received bioactive glass implantation (test group), while 17 control defects were treated with a flap procedure only (control group). The criteria for comparative observation were preoperative and postoperative probing depth (PD), clinical attachment level (CAL), bone probing depth (BPD), and gingival recession. RESULTS: Reductions in PD were observed in both groups (P<0.01). The reduction in PD was significantly greater in the test group when preoperative PD exceeded 7 mm (P<0.01). Improvements in CAL were also observed in both groups (P<0.01), with the test group showing significantly greater gains (P<0.05). In those cases where preoperative CAL was less than 7 mm, there was no statistically significant difference between the two groups. Reduction in BPD was observed in both groups, with the test group showing significantly greater reduction (P <0.01). There was no significant difference in BPD change, however, when preoperative BPD was < or =7 mm. Significantly greater reduction of BPD in the test group was observed when intrabony defect depth was >4 mm (P <0.05). Significant improvements in PD, CAL, and BPD were noted in the test group when the crestal involvement exceeded 100 degrees. Correlation test between various clinical parameters indicated that greater changes in PD and CAL in the test group were observed when preoperative CAL was large (P<0.001), and greater changes in PD (P<0.05), CAL (P<0.01), and BPD (P<0.05) were noted when preoperative BPD was large. Correlation between crestal involvement and CAL change was noted only in the control group (P<0.01). High correlations were observed between PD changes and CAL changes and between CAL changes and BPD changes in both groups. CONCLUSIONS: Use of a bone substitute in a flap operation resulted in significantly greater improvements in CAL and BPD over flap operation alone and seemed to have positive effects in postoperative PD, CAL, and BPD in those cases with more severe preoperative CAL and BPD.

Adult↗

PubMed2001

A case of del(13)(q22) with multiple major congenital anomalies, imperforate anus and penoscrotal transposition.

"13q-"syndrome is known to have widely variable manifestations, including retinoblastoma, mental & growth retardation, malformation of brain & heart, anal atresia, and anomalies of the face and limbs. Here we report a case of del(13)(q22) with multiple major congenital anomalies for the first time in Korea. The patient was born at 36(+4) weeks of pregnancy by caesarian section. Birth weight was 1490g. On examination the following features were noted: - imperforate anus, ambiguous genitalia (bifid scrotum, penoscrotal transposition, hypospadia), syndactyly of toes, absence of thumbs, abnormal facies (dolichocephaly, telecanthus, large low set ears, saddle nose, high arched palate, micrognathia). Neurocranial ultrasonography showed atrophy of the corpus callosum and multiple calcifications. He died at 14 days. Post-mortem autopsy findings showed cholestasis and fatty metamorphosis of liver, abnormal lobulation (Rt:2, Lt:1) and lymphangiectasis of the lung, VSD, ASD, PDA of heart, and acute tubular necrosis of kidney. Cytogenetic studies was confirmed to 46,XY,del(13) (q22) by Giemsa banded chromosomes from peripheral blood lymphocytes.

Abnormalities, Multiple↗

PubMed2001

The role of fetal surgery in life threatening anomalies.

The development and evolution of fetal surgery and the recognition of the fetus as a patient came from two sources. First, were those obstetricians and perinatologists who detected life threatening anomalies before birth, and re-described a hidden mortality arising from death in utero. Ultrasonography, color Doppler ultrasound and ultrafast fetal magnetic resonance imaging have since enhanced the accuracy of prenatal evaluation. Second, were those pediatricians responsible for treating newborn infants with extremely serious problems, and that appeared untreatable, although, it was believed that they could have been treated at an earlier stage of development. After the natural history of several correctable lesions had been determined and the selection criteria for intervention developed, fetal surgery emerged as a means of improving the overall morbidity and mortality rates.

Cystic Adenomatoid Malformation of Lung, Congenita↗

PubMed2001

Stenting with intravenous abciximab infusion for the treatment of left main coronary artery thrombosis during coronary angioplasty.

A 67-year-old female patient complained of exertional precordial chest pain with radiation to the left shoulder occurring over a two-month period. An acute non-Q wave anterior myocardial infarction was diagnosed. On the third day of admission, coronary angiography revealed two-vessel disease with 73% luminal narrowing of the proximal left anterior descending coronary artery and 50% luminal narrowing of the mid-right coronary artery. The initial attempt to implant a NIR stent (Boston Scientific/Scimed, Inc., Maple Grove, Minnesota) was unsuccessful. We report on the successful rescue implantation of two MAC (Maximum Arterial re-Creation) stents (Advanced Medical Technologies, Germany), in conjunction with the infusion of abciximab for the treatment of an abrupt closure due to thrombus of the left main coronary artery.

Abciximab↗

PubMed2001

Phenolic toxicity--detection and classification through the use of a recombinant bioluminescent Escherichia coli.

A genetically engineered Escherichia coli strain, DPD2540, containing a fabA::luxCDABE fusion that gives a bioluminescent output when membrane fatty acids are limited was used to determine the extent to which phenolics result in the limitation of membrane fatty acids. Tested phenolics were found to be classifiable into two groups according to the bioluminescent response they elicited and their pKa. A dose-dependent bioluminescent response, due to fatty acid limitation, was seen for phenolics with pKa values greater than seven, which exist mainly in the protonated form (HA), while no significant bioluminescent response was seen, compared with the control, for phenolics with pKa values lower than seven, which exist almost entirely as A-. A newly modified distribution model for phenolic compounds in the cellular membrane is proposed and used to predict the bioluminescent response induced by group I phenolics and the cellular toxicity for both groups. The [HA]*, obtained with this model, shows good correlation with the various bioluminescent responses produced by group I phenolics. It was also found that the distribution ratio between the medium and the cell membrane, K1, calculated as well using the proposed model, is a good representative parameter for the cellular toxicity of the phenolic compounds according to their substituted groups when compared with the conventional method of using the octanol-water partition coefficient, log Kow. As a new parameter, the critical concentration was also shown to be a good representative of the cellular toxicity for group I phenolics to the Escherichia coli cells.

Escherichia coli↗

PubMed2001

Monitoring and classification of toxicity using recombinant bioluminescent bacteria.

Recombinant bioluminescent biosensing cells were used to detect and classify toxicity caused by various chemicals in water environments. Classification of the toxicity was realized based upon the chemicals' actions of toxicity by using DNA-, oxidative- and membrane-damage sensitive strains. Tested samples contained a single chemical or mixture of chemicals in media, wastewater, or river water. Finally, it is suggested that this method for classification of toxic chemicals in wastewater or other aqueous systems may be adopted for primary screening steps of the samples and can give useful information about the samples' characteristics.

Bacteria↗

PubMed2001

Therapeutic effect of bee venom in sows with hypogalactia syndrome postpartum.

The objective of this study was to determine the clincotherapeutic effect of whole bee venom in hypogalactic sows postpartum. Sows after parturition were assigned to treated and nontreated control groups. In the treated group, 22 sows were bee acupunctured once a day for 3 consecutive days. Honeybees (Apis mellifera L.) for bee acupuncture were about 15 days after metamorphosis. One live bee was used to sting the acupoints known as Yang-ming (ST-18, 1.5 cm lateral to the base of the last 2 pairs of teats) and Jiao-chao (GV-1, at the indentation between the base of tail and the anus). In the control group, 20 sows were intramuscularly injected with a standard dosage of penicillin G (400,000 IU/head) once a day for 3 consecutive days. At post-treatment, 85.0% of the drug-treated control and 90.9% of the bee venomtreated group recovered from hypogalactia syndrome. The advantages of apitherapy were that the patients did not have stress because they were not restrained for a long period. The result suggested that apitherapy using bee venom is an effective treatment for sows with hypogalactia syndrome postpartum.

Acupuncture Points↗

PubMed2001

Prophylactic effect of plaster and cataplasm contained ketoprofen in rats with adjuvant arthritis.

This study demonstrates that prophylactic effect of plaster and cataplasm contained ketoprofen in adjuvant arthritis therapy by X-ray. Adjuvant arthritis was induced by a single injection of Freund's complete adjuvant. Mature female Sprague-Dawley rats were designated to 3 groups such as nontreated control, plaster-treated (PT) and cataplasm-treated (CT), each of which was composed of ten animals. The PT and the CT groups showed reduced primary paw swelling, but secondary paw swelling was not affected. Bony changes were observed in all regions of the femur and tibia of the nonadjuvant-injected leg and the adjuvant-injected leg. The mean radiographic scores of the PT and the CT groups were significantly lower than those of the control group from day 0 to 7 of the experimental period (P<0.05, P<0.01). The CT rats showed reduced poly-arthritis development than the PT rats. Our results suggest that radiographic assessment of bony changes is more suitable for measuring changes in long bones such as femur or tibia than in vertebrae. The prophylactic effect of CT prominently suppressed edematous swelling and bony changes in arthritic limb compared with PT.

Animals↗

PubMed2000

Survival and stability of bifidobacteria loaded in alginate poly-l-lysine microparticles.

Bifidobacteria-loaded alginate microparticles were prepared by spraying a mixture of alginate and bifidobacteria culture using an air atomization method. Survival and stability of bifidobacteria loaded in microparticles were then evaluated. Survival of bifidobacteria from alginate poly-l-lysine microparticles was significantly increased when MRS broth or yeast extract was added in simulated intestinal fluid (pH 6.8). The number of bifidobacteria gradually increased for 8 h (10(8) cfu/g) and then reached about 10(9)-10(10) cfu/g when incubated over 12 h in intestinal fluid containing 0.5% yeast extract and 0.05% L-cysteine. The survival of bifidobacteria was highly dependent on the pH of the exposing media. When the bifidobacteria was immobilized with alginate or even poly-l-lysine treatment, the survival of bifidobacteria was highly enhanced in the low pH conditions (ca. > 10(8) vs. < 10(3) cfu/g). The stability of free flowing bifidobacteria-loaded alginate poly-l-lysine microparticles was significantly improved during storage at 4 degrees C in a refrigerator when compared to bifidobacteria cultures. The bifidobacteria-loaded alginate poly-l-lysine microparticles could be applied to various dairy products.

Alginates↗

PubMed2000

Expression of brain/kidney protein in Müller cells of rat retina following transient ischemia.

We have investigated the expression and cellular localization of brain/kidney (B/K) protein in the rat retina following transient ischemia. In the normal retina, strong B/K immunoreactivity was localized to some ganglion cells. In addition, a few radial Muller cell processes showed B/K immunoreactivity. Following ischemia and reperfusion, most B/K-labeled ganglion cells were lost, whereas between 1 day and 2 weeks post-lesion B/K immunoreactivity appeared in many more Muller cell processes with increasing intensity. Quantitative evaluation by immunoblotting confirmed that B/K expression then decreased progressively, to 35% of control values at four weeks post-lesion. Our findings suggest that Muller cells are involved in the pathophysiology of retinal ischemia through the expression of B/K following transient ischemia.

Animals↗

PubMed2000

Phosphatidylinositol 3-kinase stimulates muscle differentiation by activating p38 mitogen-activated protein kinase.

The activation of both phosphatidylinositol 3-kinase (PI3-kinase) and p38 mitogen-activated protein kinase (p38 MAPK) is required for muscle differentiation. However, it is not known whether the signals from these two kinases interact during this process. In this work, we have investigated this using H9c2 cardiac myoblasts. The p38 MAPK-specific inhibitor SB203580 blocked muscle differentiation and suppressed the expression of myogenin and myosin heavy chain in a concentration-dependent manner. Consistent with this, expression of a wild-type p38 MAPK (Ha-p38) or a constitutively active MAPK kinase 6 (MKK6(glu)) promoted the rate of differentiation into multinucleated myotubes. LY294002, a PI3-kinase inhibitor, suppressed in a dose-dependent manner not only muscle differentiation but also activation of p38 MAPK. In addition, expression of a constitutively active form of PI3-kinase (p110*) enhanced myotube formation and p38 MAPK activation, while expression of a dominant negative form of PI3-kinase (Deltap85) attenuated these responses. Furthermore, SB203580 suppressed differentiation of H9c2 cells expressing p110*. Interestingly, LY294002 also suppressed differentiation of H9c2 cells expressing Ha-p38 or MKK6(glu). However, SB203580 did not affect PI3-kinase activity, suggesting that PI3-kinase myogenic signaling to p38 MAPK is unidirectional. Taken together, we concluded that PI3-kinase activates p38 MAPK, which in turn stimulates muscle differentiation, but that p38 MAPK does not substitute for PI3-kinase in this process.

Animals↗

PubMed2000

A planar pCO2 sensor with enhanced electrochemical properties.

To develop planar microchemical pCO2 sensing devices with improved electrochemical properties, we combined two advanced technologies. One is a differential sensor arrangement to simplify the microfabrication procedure by employing pH-sensitive gas-permeable membranes, and the other is the use of an enzyme (carbonic anhydrase) to shorten total measurement time by accelerating the rate of CO2 hydration. The adhesion of the polyurethane-matrix gas-permeable membrane is enhanced significantly by incorporating a silanizing reagent (silicon tetrachloride), improving the stability and extending sensor lifetime. The proposed differential pCO2 microelectrodes exhibited significantly improved performance in their preconditioning period, response and recovery times, stability, response slope, and lifetime.

Biosensing Techniques↗

PubMed2000

Transforming growth factor-beta induces apoptosis in activated murine T cells through the activation of caspase 1-like protease.

Transforming growth factor-beta (TGF-beta) has been known as a potent immunosuppressive cytokine that can induce apoptosis in lymphoid cells. We established an IL-2-independent cell line, CTLL-2A, from murine T cell line CTLL-2. CTLL-2A expressed higher levels of CD95, CD69, and CD18 molecules than CTLL-2 did, suggesting a more activated state in CTLL-2A than in the CTLL-2 by phenotype. Exposing both CTLL-2 and CTLL-2A to TGF-beta results in differential apoptosis patterns defined by DNA fragmentation and plasma membrane alteration. Among the bcl-2 family members, bcl-2, bcl-w, and bcl-x(L) were also differently expressed in these two cell lines. In CTLL-2A, bcl-x(L) was amplified as a major anti-apoptotic molecule, and TGF-beta-induced cell death was more enhanced than in the original cell line. Caspase 1-like protease was activated by TGF-beta treatment and consequently it cleaved bcl-x(L) in CTLL-2A. TGF-beta-induced DNA fragmentation and cleavage of bcl-x(L) were inhibited by pretreatment with tetra peptide caspase 1 inhibitor, YVAD.cmk. These findings suggest that TGF-beta induces cell death in activated murine T cells through cleavage of bcl-x(L) via activated caspase 1-like protease, which may act as an important executor in that process.

Animals↗

PubMed2000

Hydrophobic ion pair formation between leuprolide and sodium oleate for sustained release from biodegradable polymeric microspheres.

Leuprolide acetate, an analogue of luteinizing hormone-releasing hormone (LH-RH), was hydrophobically ion paired with a long chain fatty acid, sodium oleate, in an aqueous solution. Solution behaviors of the complex formed between leuprolide and sodium oleate were investigated in terms of aqueous solubility, turbidity, particle size, and zeta potential as a function of molar ratio between the two species. It was found that with increasing the stoichiometric molar amounts of sodium oleate to leuprolide approached up to 2.5-3, the solution became gradually turbid with increasing particle sizes, indicating leuprolide precipitation as a result of hydrophobic ion pairing. On the other hand, beyond that critical molar ratio range, the solution turned into clear with much reduced particle size, indicative of micelle formation. The hydrophobically modified leuprolide-oleate complex was lyophilized and directly encapsulated within biodegradable poly(D, L-lactic-co-glycolic acid) (PLGA) microspheres via a single oil-in-water (O/W) emulsion method. Microsphere morphology, leuprolide release behavior, and polymer mass erosion profiles were examined in comparison to the PLGA microspheres prepared with free leuprolide.

Delayed-Action Preparations↗

PubMed2000

Cytoprotective effect of arginine deiminase on taxol-induced apoptosis in DU145 human prostate cancer cells.

We purified and partially sequenced a cytostatic protein from the ASC-17D Sertoli cell-conditioned media (rSCCM) showing a molecular weight of 90 kDa with homodimeric composition. N-terminal amino acid analysis revealed that the protein was homologous to the arginine deiminase (ADI) of Mycoplasma arginini. We found ADI enzyme activity in rSCCM and the abolishment of the growth inhibitory effect by the supplement of L-arginine. Thus, we confirmed that the cytostatic activity in rSCCM was due to the depletion of extracellular L-arginine by ADI. Apparent increase of cell death or DNA fragmentation was not observed in DU145 cells cultured in the presence of ADI. Incubation of DU145 cancer cells with taxol resulted in a marked DNA fragmentation, whereas pretreatment with ADI or cycloheximide protected the cells from taxol-induced apoptosis. Preincubation of the cells with ADI inhibited S35-methionine incorporation into protein synthesis in a dose dependent manner. These data suggest that ADI-induced arginine depletion may inhibit protein synthesis, and result in the protection of apoptotic cell death that requires new protein synthesis.

Amino Acid Sequence↗

PubMed2000

Glutamate and aspartate impair memory retention and damage hypothalamic neurons in adult mice.

We examined the effects of systemic administration of monosodium glutamate (MSG) or aspartate (ASP) on the memory retention and neuronal damage in the brains of adult mice. Compared with the control mice, a single intraperitoneal injection of either 4.0 mg/g MSG or 0.5 mg/g ASP after acquisition trial significantly shortened the response latency in the passive avoidance test, accompanying by the transient weight loss. Histopathological analysis of the brains of these mice revealed that neurons in the arcuate nucleus of hypothalamus were damaged markedly by MSG (4.0 mg/g) or ASP (0.5 mg/g). Other brain areas including cerebral cortex and hippocampus did not show any pathological changes. These findings suggest that systemic administration of MSG or ASP could impair memory retention and damage hypothalamic neurons in adult mice.

Animals↗

PubMed2000

Effects of Polycomb group mutations on the expression of Ultrabithorax in the Drosophila visceral mesoderm.

The Polycomb group (PcG) genes encode repressors of many developmental regulatory genes including homeotic genes and are known to act by modifying chromatin structure through complex formation. We describe how Ultrabithorax (Ubx) expression is affected by the PcG mutants in the visceral mesoderm. Mutant embryos of the genes extra sex combs (esc), Polycomb (Pc), additional sex combs (Asx) and pleiohomeotic (pho) were examined. In each mutation, Ubx was ectopically expressed outside of their normal domains along the anterior-posterior axis in the visceral mesoderm, which is consistent with the effect of PcG proteins repressing the homeotic genes in other tissues. All of these four PcG mutations exhibit complete or partial lack of midgut constriction. However, two thirds of esc mutant embryos did not show Ubx expression in parasegment 7 (PS7). Even in the embryos showing ectopic Ubx expression, the level of Ubx expression in the PcG mutations was weaker than that in normal embryos. We suggest that in PcG mutations the ectopic Ubx expression is caused by lack of PcG repressor proteins, while the weaker or lack of Ubx expression is due to the repression of Ubx by Abd-B protein which is ectopically expressed in PcG mutations as well.

Animals↗

PubMed2000

Antisense oligonucleotide of clusterin mRNA induces apoptotic cell death and prevents adhesion of rat ASC-17D Sertoli cells.

Clusterin has been known to play important roles in cell-cell and/or cell-substratum interactions. Recently we reported the transient expression of clusterin in pancreatic endocrine cells during the early developmental stages and suggested a role in aggregating the endocrine cells for islet formation. In the present study, we have investigated the involvement of clusterin in cell-substratum interaction by the inhibition of clusterin synthesis using antisense oligonucleotide. The expression of clusterin was transiently increased as early as 2-8 h after plating the ASC-17D Sertoli cells to the culture flask, which was the period of cell attachment. In addition, up-regulation of clusterin mRNA was so much greater when the Sertoli cells were plated on the petri dish for the bacterial culture instead of in a animal cell culture flask that therefore, the cells failed to attach to it. These findings suggested that interruption of cell to plate substratum interaction might lead to over-expression of clusterin from Sertoli cells to induce cell to cell aggregation or, perhaps, to re-establish attachment with the substratum. Transfection of ASC-17D Sertoli cells with a 20-base antisense oligonucleotide against clusterin mRNA resulted in extracellular release of LDH and DNA fragmentation. Sertoli cell death by antisense oligonucleotide of clusterin was sequence specific and dose dependent. Treatment of antisense oligonucleotide induced a marked reduction of synthesis for clusterin protein, but not for clusterin mRNA expression, suggesting the translational suppression of clusterin by antisense oligonucleotide. Further, microscopic observation showed that more noticeable cell death was induced by treating the antisense prior to plating the cells than by treating after cell attachment to the plate. From these results, we speculate that down-regulation of clusterin expression in the anchorage-dependent Sertoli cells prevents them from attaching to the plate, and therefore induces cell death.

Animals↗