Biomedical subjects

I H Choi

Publications and source records attributed to I H Choi.

At least 19 recordsLinked to original sources

PubMed2006

Morphometric analysis of acetabular dysplasia in cerebral palsy.

We carried out a morphometric analysis of acetabular dysplasia in patients with cerebral palsy requiring hip surgery using three-dimensional CT. We evaluated 54 hips in 27 patients. The contralateral normal hips of ten patients with unilateral Perthes' disease were used as a control group. The acetabular defects were assessed qualitatively as anterior, posterior or global. Quantitative assessments were made using three-directional acetabular indices (anterosuperior, superolateral and posterosuperior) and measured by multiplanar reformation, from which we calculated the acetabular volume. In the qualitative study, posterior defects were most common in the subluxation group whereas global defects predominated in the dislocation group. In the quantitative study, all acetabular indices in both the subluxation and dislocation groups were higher than those in the control group and the superolateral indices showed a tendency to elevation in the dislocation group. The acetabular volume was largest in the control group, smallest in the dislocation group, and intermediate between the two in the subluxation group.

Acetabulum↗

PubMed2005

Distraction osteogenesis for segmental bone defect. Physeal change after acute bone shortening followed by gradual lengthening in a rabbit tibia model.

We investigated physeal change after acute bone shortening followed by distraction osteogenesis in a rabbit tibia model. Distraction osteogenesis was performed on acutely shortened right rabbit tibia after removing a diaphyseal segment until distraction reached the length of the excised segment. Sixty animals were divided into three groups (n=20) according to the amount of shortening (20, 30, and 40% of original length) and radiographic, immunohistochemical, and histomorphometric analyses were performed to evaluate the physeal activity. The results showed no differences between groups and all animals could recover the original length without growth retardation. There was no notable venous congestion or lymphatic kinking associated with acute shortening. These results suggest that distraction osteogenesis at the primary site of shortening may have little adverse effects on the growth plate, when the shortening can provide sufficient soft tissue without vascular compromise and the amount of lengthening does not exceed that of shortening.

Animals↗

PubMed2005

Effects of chemically amended litter on broiler performances, atmospheric ammonia concentration, and phosphorus solubility in litter.

The effects of 6 different litter amendments on broiler performance, level of atmospheric ammonia (NH3) concentration, and soluble reactive phosphorus (SRP) in litter was determined. Through 3 experiments conducted on 2 different commercial farms, one chemical amendment was added to the litter and then was compared with a control. Broiler performance was not affected by any of the amendments except the ferrous sulfate amendment for which mortality was 25.5%. Application of aluminum chloride (AlCl3 x 6H2O) to the litter lowered atmospheric ammonia concentrations at 42 d by 97.2%, whereas ferrous sulfate (FeSO4 x 7H2O) lowered it by 90.77%. Ammonia concentrations were reduced by 86.18, 78.66, 75.52, and 69.00% by aluminum sulfate [alum or Al2(SO4)3 x 14H2O)], alum + CaCO3, aluminum chloride + CaCO3, and potassium permanganate (KMnO4), respectively, when compared with each control at 42 d. Each amendment except KMnO4 significantly reduced SRP contents. Alum and aluminum chloride were the effective compounds evaluated on the commercial farms with respect to reducing ammonia contents, phosphorus solubility, and mortality.

Air Pollution↗

PubMed2005

The bicompartmental acetabulum in Perthes' disease: 3D-CT and MRI study.

The bicompartmental acetabulum is one of the morphological changes which may be seen in children with Legg-Calvé-Perthes' disease. Three-dimensional CT and MRI were used to analyse the detailed morphology of the acetabulum with special reference to its inner surface, in 16 patients with Perthes' disease and a bicompartmental acetabulum.The bicompartmental appearance was seen on the coronal plane image through the acetabular fossa. The lunate surface was seen to grow laterally resulting in an increased mediolateral thickness of the triradiate cartilage. On the horizontal plane images, the acetabular fossa had deepened and had a distinct prominence at its posterior border. The combination of these morphological changes resulted in a bicompartmental appearance on plain radiography. Acetabular bicompartmentalisation appears to be the result of an imbalance of growth between the cartilage-covered lunate surface and the cartilage-devoid acetabular fossa.

Acetabulum↗

PubMed2005

Use of fouling resistant nanofiltration and reverse osmosis membranes for dyeing wastewater effluent treatment.

Dyeing wastewater was post-treated by using nanofiltration (NF) and reverse osmosis (RO) membranes. To reduce membrane fouling, poly (vinyl alcohol) (PVA) with a neutral charge was coated on NF and RO membranes. The effect of surface charge and surface roughness on membrane fouling was investigated. Dyeing wastewater was pre-treated by using coagulation, activated sludge process, and MF process to investigate the effect of the pre-treatment on the membrane fouling. It is demonstrated that the extent of fouling is significantly influenced by the surface roughness and the surface charge on the NF and RO membranes. A membrane with a smooth and neutral surface was fouled less. The pre-treatment was essential for avoiding NF and RO membranes fouling. The quality of the final permeate was acceptable for water reuse.

Bioreactors↗

PubMed2004

Overexpression of LIM kinase 1 renders resistance to apoptosis in PC12 cells by inhibition of caspase activation.

LIM kinases (LIMKs) regulate actin polymerization by phosphorylating cofilin and are predominantly expressed in neural tissue. In this study, the effect of LIMK1 overexpression in PC12 cell apoptosis was investigated. PC12 cells overexpressing the wild-type LIMK1 were more resistant to serum-withdrawal-induced cell death and the level of caspase 3 activation in these cells was lower than in the control PC12 cells or than in the PC12 cells expressing a mutant LIMK1 lacking the kinase domain. The inhibition of JNK activation was observed in the PC12 cells overexpressing the wild-type LIMK1 after serum withdrawal. These results suggest that the LIMK1 might allow resistance to apoptosis in PC12 cells by inhibiting JNK activation.

Actin Cytoskeleton↗

PubMed2004

Valgus femoral osteotomy for hinge abduction in Perthes' disease. Decision-making and outcomes.

We studied, clinically and radiologically, the growth and remodelling of 21 hips after valgus femoral osteotomy with both rotational and sagittal correction for hinge abduction in 21 patients (mean age, 9.7 years) with Perthes' disease. The exact type of osteotomy performed was based on the pre-operative clinical and radiological assessment and the results of intra-operative dynamic arthrography. The mean IOWA hip score was 66 (34 to 76) before surgery and 92 (80 to 100) at a mean follow-up of 7.1 years (3.0 to 15.0). Radiological measurements revealed favourable remodelling of the femoral head and improved hip joint mechanics. Valgus osteotomy, with both rotational and sagittal correction, can improve symptoms, function and remodelling of the hip in patients with Perthes' disease.

Bone Remodeling↗

PubMed2001

Hydrogen peroxide triggers the expression of Fas/FasL in astrocytoma cell lines and augments apoptosis.

Fas expression increases in perinecrotic areas of glioblastoma. In this study the up-regulation of Fas/FasL by oxidative stress was shown. H(2)O(2) exposure increased Fas expression in two astrocytoma cell lines and cells became sensitive to agonistic anti-Fas antibody. FasL was up-regulated in astrocytoma cells. Apoptosis of Molt-4 cells was augmented by astrocytoma cells pretreated with H(2)O(2). Our findings suggest up-regulation of Fas in astrocytoma cells may lead them to be sensitive to apoptosis when cells are in oxidative stress. Whereas, the up-regulation of FasL may render astrocytoma cells cytotoxic to neighboring brain tissues and infiltrating immune cells.

Apoptosis↗

PubMed2001

Water wave communication in the genus Bombina (amphibia).

Amphibians were phylogenetically the first vertebrates to leave the aquatic environment and cope with terrestrial conditions including effects of gravity and substrate on movement and communication. Studies of extant primitive amphibians, which have conserved ancestral morphology and behavior, may help us to understand how gravitational adaptation from aquatic to terrestrial environments occurred. The anuran genus Bombina is a candidate for this type of investigation. In particular, a member of this genus, B. orientalis, is known for its low reaction threshold to minor changes of angular acceleration. We hypothesize that a heightened sensitivity to angular and mechanical accelerations evolved with wave communication. Comparisons of such behavior among B. variegata, B. bombina and B. orientalis may shed light on the evolution of reproductive systems based on water wave communication and relevant vestibular sensitivity. This may represent a transition to derived vocalization modes, which is seen in B. bombina to a certain degree.

Animal Communication↗

PubMed2001

The treatment of recurrent arthrogrypotic club foot in children by the Ilizarov method. A preliminary report.

Between 1994 and 1997 we used the Ilizarov apparatus to treat 12 recurrent arthrogrypotic club feet in nine patients with a mean age of 5.3 years (3.2 to 7). After a mean of three weeks (two to seven) for correction of the deformity and 1.5 weeks (one to four) for stabilisation in the apparatus, immobilisation in a cast was carried out for a mean of 14 weeks (7 to 24). The mean follow-up period was 35 months (27 to 57). Before operation there were one grade-II (moderate), eight grade-III (severe) and three grade-IV (very severe) club feet, according to the rating system of Dimeglio et al. After operation, all the club feet except one were grade I (benign) with a painless, plantigrade platform. Radiological assessment and functional evaluation confirmed significant improvement. Two complications occurred in one patient, namely, epiphysiolysis of the distal tibia and recurrence of the foot deformity. These results suggest that our proposed modification of the Ilizarov technique is effective in the management of recurrent arthrogrypotic club foot in young children.

Arthrogryposis↗

PubMed2000

Affinity maturation of natural antibody using a chain shuffling technique and the expression of recombinant antibodies in Escherichia coli.

The affinity of natural antibody (Ka = 8 x 10(6) M(-1)) recognizing preS1 of hepatitis B virus (HBV) was improved by replacing the heavy (H) chain gene with repertoires of VH genes, obtained from two nonimmunized donors. Two separate clones, 1C2 and 1E4, showed affinities of 2.3 x 10(7) and 5.2 x 10(7) M(-1), which were increased by factors of 2.8 and 6.5, respectively, compared to the parental clone. Recombinant scFvs (rscFvs) were expressed as fusion protein with minor coat protein, pIII, and secreted into medium after 3 h of induction with 1 mM IPTG. The expression level of functional rscFv capable of binding to preS1 reached a peak after 6-10 h (1C2) and 8-10 h (1E4) of IPTG induction, and afterwards decreased gradually. In order to achieve the overexpression of rscFv in E. coli, gene encoding scFv of 1C2 or 1E4 was inserted into pRSET vector. RscFvs were overexpressed as cytoplasmic inclusion bodies in E. coli BL 21 strain, which were denatured and carefully refolded using a continuous dialysis system. The purified recombinant fragments were pure when analyzed by SDS-PAGE and had the predicted size of 34 kDa. Clone 1E4 used the heavy chain gene belonging to family VII and subgroup III. Chain shuffling offers an alternative to random point mutation for affinity maturation of human antibody in vitro.

Amino Acid Sequence↗

PubMed2000

Diversity of the p70 killer cell inhibitory receptor (KIR3DL) family members in a single individual.

NK cells and some T cells express members of a multigenic family of killer cell inhibitory receptors (KIRs) including p70 KIR (KIR3DL) and p58 KIR (KIR2DL) family that recognize polymorphic class I MHC molecules on target cells and transmit an inhibitory signal to prevent killer cell-mediated cytoxicity. The cDNA sequences of p70 KIR family members reported so far suggest that the p70 KIR gene consists of a multigene complex and that each gene may exhibit certain degrees of polymorphism. However, it is not clear how diverse the repertoire of the p70 KIR family is, particularly in a single individual. To address this question in more detail and to determine some indication as to the origin of the diversity, we cloned p70 KIR cDNAs from a single individual. We identified nine new KIRs that are different from the previously reported ones. A comparison of the amino acid sequences with published sequences of p70 KIRs showed that two clones belonged to the KIR3DL1 family, five clones belonged to the KIR3DL2 family, one clone belonged to the KIR2DL4 family, and one clone appeared to be an alternatively spliced form of p70 KIR. These results suggested that the repertoire of p70 KIR family members in a single individual is highly diverse. It is not clear how the diverse receptors are generated in a single individual, but a comparison of amino acid sequences of p70 KIR family members suggested that some of them may be encoded by distinct genes or their alleles, while others may be generated by a recombination mechanism and/or an alternative splicing mechanism at the maturation of the mRNA transcripts.

Alternative Splicing↗

PubMed2000

Light chain of natural antibody plays a dominant role in protein antigen binding.

Examinations of the contribution and the specificity of heavy (H) and light (L) chains of natural antibodies to antigen binding may help us to better understand antigen recognition and the development of naive B cells. We previously generated natural Fab antibody fragments reactive to preS1 of HBV using a naive, non-immunized Fab antibody library derived from peripheral B cells of a normal healthy volunteer. We now constructed expression vectors for the Fd (VH + CH1), L chain, and scFv fragments using the sequences encoding parental Fabs as a source of natural antibody genes. The recombinant antibody fragments were expressed as inclusion bodies in E. coli BL21 (DE) cells. When denatured and then refolded, the antibody fragments retained their binding properties. Recombinant L chains and scFvs exhibited three- to 40-fold higher affinities (in the order of 10(7) M(-1)) over the parental Fabs, whereas the affinities of Fds (in the order of 10(5) M(-1)) were much lower compared to the parental Fabs. The results obtained from sandwich ELISA revealed that the L chains bound the virus more efficiently than Fds. Additional experiments were performed to evaluate the specificity of the recombinant fragments for surface proteins of HBV. Fds and L chains were reactive towards HBsAg and the preS2 peptide as well as preS1 and showed patterns of epitope recognition quite different from those of parental Fabs. The data presented here demonstrate that the prominence of the L chain in determining protein binding activity is a property of natural antibodies and is quite unlike the antibodies induced by immunization, and that the specificity of Fab is not determined by the individual antibody chain but by the correct pairing of H and L chain.

Antibody Affinity↗

PubMed2000

Vascular proliferation and blood supply during distraction osteogenesis: a scanning electron microscopic observation.

This scanning electron microscopic study examined the spatial and temporal features of proliferating vessels of regenerating bone tissue and blood supply during distraction osteogenesis. A rat model of tibial lengthening was used with a protocol divided into a latency period of 7 days, a distraction period that lasted 14 days with a daily distraction rate of 0.5 mm in two steps, and a consolidation period of 21 days. Vascular casting was done on the hindlimbs before osteotomy and on postoperative days 7, 14, 21, 28, and 42. Scanning electron microscopic findings were correlated with radiological and histological observations. On days 7 and 14, the proliferation of periosteal vessels was pronounced and there was distinct subperiosteal bone formation on the osteotomized surfaces. On day 21, vascular branches from the medullary canal of the host bone formed a vascular network, which gave rise to multiple axial, straight vascular branches, running parallel to the direction of distraction, toward the interzone, in accordance with the progress of mineralization. On day 28, the periosteum provided vascularization to the peripheral side of the interzone whereas the center of the interzone was still relatively avascular. On day 42, the periosteal and medullary vascular channels were completely connected at the distraction site including the interzone, which was occupied by developing and mature bone trabeculae. These results suggest that vascular proliferation occurs actively during the latency and distraction periods and then gradually decreases over time. A close temporal and spatial relationship exists between formation of regenerated bone and vascular proliferation of the periosteum and medullary canal.

Animals↗

PubMed2000

Seasonal biochemical plasticity of a flight muscle in a bat, Murina leucogaster.

Cellular and biochemical responses of the pectoral muscle to variation in seasonal activity were studied in the bat, Murina leucogaster ognevi. We collected bats in mid-hibernation (February), end-hibernation (April), and mid-summer (August) to track major activity periods in their annual cycle. Our findings indicated that myofiber cross-sectional area decreased to 68% between mid- and end-hibernation, but returned to the winter level in mid-summer. Total soluble protein and total RNA concentrations were not altered over these sampling periods. Oxidative potential gauged by citrate synthase activity increased 1.47-fold from mid- to end-hibernation and then remained at the similar level in mid-summer. Glycolytic potential gauged by lactate dehydrogenase activity changed little between mid- and end-hibernation but increased 1.42-fold in summer, compared with the winter level. Thus, the myofibers underwent disuse atrophy during hibernation, while enzymatic catalytic function recovered towards the level of mid-summer.

Adenosine Triphosphatases↗

PubMed2000

Anuran metamorphosis: a model for gravitational study on motor development.

Limbs and supporting structures of an organism experience a full weight of its own when it lands from water, because neutral buoyancy in the aquatic habitat will be no longer available in the terrestrial world. Metamorphosis of anuran amphibians presents a good research model to examine how this transition from non-loading to weight-loading affects development of motor capacity at the time of their first emergence on land. Our video analysis of the transitional anurans, Rana catesbeiana, at Gosner stage 46 (the stage of complete transformation) demonstrated that the take-off speed increased 1.23-fold after the first six hours of weight-loading on the wet ground. It did not increase further during the following three days of loading, and was close to the level of mature frogs with different body mass. During development of larvae in deep water with no chance of landing through metamorphosis, both tension and power of a hindlimb anti-gravity muscle increased 5-fold between stages 37 and 46. However, the muscle contractility increased more rapidly when the larvae could access the wet ground by their natural landing behavior after stages 41-42. Muscle power, one of major factors affecting locomotory speed, was 1.29-fold greater in the loaded than in the non-loaded larvae at the transitional stage. Thus, weight-loading had a potentially significant effect on the elevation of motor capacity, with a similar extent of increment in locomotory speed and muscle power during the last stages of metamorphosis. Such a motor adjustment of the froglets in a relatively short transitional period would be important for effective ecological interactions and survival in their inexperienced terrestrial life.

Animals↗

PubMed2000

MR imaging of changes of the growth plate after partial physeal removal and fat graft interposition in rabbits.

RATIONALE AND OBJECTIVES: The most important complication of skeletal injuries involving the growth plate is growth disturbance. The purpose of this study was to evaluate MR features of growth plate modification after fat graft interposition in growth plate injury and to correlate these findings with pathological findings. METHODS: A growth plate injury model was used in 12 skeletally immature rabbits. A longitudinal drill hole 5 mm in diameter was created in the central part of the growth plate in the distal femur, bilaterally. One side was filled with autologous fat, and the contralateral defect was left empty as a control. Magnetic resonance imaging was obtained 1, 3, and 6 months after surgery, and routine histological study was performed. The authors evaluated sequential changes in MR images and the histological basis of MR findings. RESULTS: In grafted femur, the signal intensity of the grafted area was lower than that of the surrounding bone on T2-weighted images at 1 month. The growth plate defect at 3 to 6 months was modified and had a proximally tapering appearance. The ratio of the growth plate defect was smaller in the grafted femur than in the control femur after surgery. Histologically, the fat-grafted area was replaced by fibrous connective tissue. In the control femur, a bony bridge was rectangular in the longitudinal direction and showed isosignal intensity with a rim of low signal intensity on T1-weighted imaging. Histologically, the defect was filled with mature fatty marrow with new bone formation in the control femur. CONCLUSIONS: The proximally pointing appearance and the low signal intensity of the grafted area on MR suggested fibrous degeneration of grafted fat that prevented solid bony bridge formation in experimentally induced growth plate injury.

Adipose Tissue↗

PubMed2000

The Sprengel deformity. Morphometric analysis using 3D-CT and its clinical relevance.

We evaluated scapular dysplasia and malposition in 15 patients with the Sprengel deformity using three-dimensional CT (3D-CT). The shape, height-to-width ratio, the areas of both scapulae, the anterior curvature of the supraspinous portion and glenoid version were assessed on scapular posterior, medial and inferior views. The degree of rotation and superior displacement were measured on the trunk posterior view. The omovertebral connection was also assessed and correlated with the operative findings. Most of the affected scapulae had a characteristic shape with a decrease in the height-to-width ratio and were larger than the contralateral scapulae. There was an inverse relationship between scapular rotation and superior displacement. The typical curve of the supraspinous portion of the scapula was seen in only three cases. There was no significant difference in glenoid version. The point of tethering of the omovertebral connection may determine the shape, rotation and superior displacement of the scapula. 3D-CT was helpful in delineating the deformity in detail, and in planning scapuloplasty.

Child↗