Biomedical subjects

K N Kim

Publications and source records attributed to K N Kim.

At least 19 recordsLinked to original sources

PubMed2006

Clinical and radiological results following cervical arthroplasty.

BACKGROUND: This was a retrospective study of clinical and radiological results of cervical arthroplasty using the Bryan cervical disc prosthesis to evaluate the efficacy of arthroplasty in clinical applications. METHODS: A total of 46 patients underwent arthroplasty of a single level using the Bryan disc prosthesis. Clinical outcome was assessed using the visual analogue scale (VAS) and the neck disability index (NDI). All patients were evaluated using preoperative and postoperative static cervical spine radiographs to compare cervical sagittal balance. Dynamic cervical spine radiographs were used to compare movement at the level of the procedure, movement at the adjacent level and movement of the whole cervical spine. FINDINGS: With the exception of four patients with aggravated neck pain, the NDI and VAS scores decreased significantly in late follow-up evaluations. The range of movement of the whole cervical spine, the functional segmental unit, and the adjacent segments were preserved after arthroplasty. The sagittal alignment of the cervical spine showed kyphosis after surgery but restored lordosis at a later time. The postulated cause of kyphotic changes include "over-milling" at the dorsal endplate, inappropriate angle of disc insertion, structural absence of lordosis in the Bryan disc, removal of posterior longitudinal ligament, and pre-existing kyphosis. CONCLUSIONS: Arthroplasty using the Bryan disc appears to be safe and provided a favorable preliminary clinical and radiological outcome. Postoperative kyphosis can be prevented by understanding the biomechanical properties of the Bryan disc. Future studies will need to address the association between postoperative kyphosis, clinical outcome and adjacent segment disease.

Adult↗

PubMed2004

Primary malignant fibrous histiocytoma extending into spinal canal through intervertebral foramina.

A 60-year-old man was referred to us because of gradual-onset radiculopathy in his left leg for 2 months. Magnetic Resonance Imaging (MRI) of the lumbar spine demonstrated a relatively homogeneous huge mass in the left paravertebral area from L1 to L3 (Fig. 1A, B). Axial MRI scan (Fig. 1C) confirmed the extension of the tumour into the adjacent spinal canal through the neural foramina, forming an extradural mass, which resulted in the compression of both the dural sac and the nerve roots. The patient was operated on by a staged-resection. First, a left retroperitoneal approach was performed for the paraspinal mass. The tumour appeared brown to tan in color and was moderately firm. Nine days after his first operation, the patient underwent a resection of the intraspinal/extradural tumour by a posterior approach. After the left L1-2 hemilaminectomy was performed, the extradural tumour was easily identified, dissected, and completely removed. Microscopically, it was a highly cellular tumour composed of anaplastic cells assuming a gigantic size with bizarre nuclei, which were admixed with inflammatory cells (Fig. 1D). The tumour cells were immunohistochemically characterized by positive staining for vimentin confirming its mesenchymal origin, and CD68 consistent with histiocyte-like qualities (Fig. 1E, F). A diagnosis of inflammatory malignant fibrous histiocytoma (MFH) could be made. Postoperatively, the patient made an uneventful recovery and received radiotherapy as an adjuvant therapy.

Histiocytoma, Benign Fibrous↗

PubMed2004

The influence of lithium fluoride on in vitro biocompatibility and bioactivity of calcium aluminate-pMMA composite cement.

The objective of this study is to assess the influence of lithium fluoride on in vitro biocompatibility and bioactivity of calcium aluminate (CA)-polymethylmethacrylate (PMMA) composite cement exhibiting quick setting time ( < 15 min), low exothermic temperature (< 47 degrees C), and high compressive strength (> 100 MPa). The biocompatibility was measured by examining cytotoxicity tests such as the agar diffusion test with L929 cell line and the hemolysis test with fresh rabbit blood. To estimate the bioactivity of CA-PMMA composite cement, we determined hydroxyapatite (HAp) formation on the surface of composite cement in the simulated body (SBF) solution by using thin-film XRD, XPS, SEM, EPMA and ICP-AES. The results of biocompatibility tests indicated that all experimental compositions of this study had no cytotoxicity and no hemolysis so that there was no cytotoxicity with regard to non-reacted monomers (MMA and TEGDMA) and lithium fluoride. The results of bioactivity tests revealed that CA-PMMA composite cement without lithium fluoride did not form HAp on its surface after 60 days of soaking in the SBF. On the other hand, LiAl2(OH)7 . 2H2O and HAp were formed on the surface of CA-PMMA composite cement including 1.0% by weight of lithium fluoride after 7 and 15 days of soaking in the SBF, respectively. The 5 microm of LiAl2(OH)7 . 2H2O and HAp mixed layers were formed on the surface of specimen after 60 days of soaking in the SBF.

Acrylic Resins↗

PubMed2004

Effects of the interaction between the C677T 5,10-methylenetetrahydrofolate reductase polymorphism and serum B vitamins on homocysteine levels in pregnant women.

OBJECTIVE: The purpose of this study was to investigate the effect of the interaction between the C677T mutation in the 5,10-methylenetetrahydrofolate reductase (MTHFR) genotypes and serum levels of B vitamins on serum homocysteine levels in pregnant women. DESIGN: A cross-sectional study. SETTING: Ewha Womans University Hospital, Seoul, Korea. SUBJECTS: A total of 177 normal pregnant women, 24.6+/-1.1 weeks of gestation, in a 6-month period during 2001-2002. INTERVENTIONS: Serum vitamin B2, vitamin B6, and homocysteine analyses were conducted using high-performance liquid chromatography methods. Serum folate and vitamin B12 concentrations were determined using a radioimmunoassay kit. MTHFR gene mutation was investigated by the polymerase chain reaction of a genomic DNA fragment. RESULTS: Serum homocysteine was higher in women with the T/T genotype than those with the C/T or C/C genotype of the MTHFR gene (P<0.05). Serum homocysteine was negatively correlated with serum folate in all MTHFR genotypes (P<0.001), and the correlation between the two serum levels was the strongest in the T/T genotype. Serum homocysteine was higher in the subjects with the T/T MTHFR genotype only when the serum folate was below the median level. Explanatory power of B vitamin status as predictors of serum homocysteine levels was more pronounced in the T/T genotypes (68.5%) compared with the C/T (37.9%) or C/C genotypes (20.6%). CONCLUSIONS: Serum homocysteine levels in pregnant women varied significantly with MTHFR genotype and the serum B vitamin status. Higher serum folate, vitamin B2, and vitamin B12 concentrations may lessen the MTHFR genotypic effect on serum homocysteine levels.

Adult↗

PubMed2003

Intermediate filament nestin expressions in human cord blood monocytes (HCMNCs).

OBJECTS: Nestin is an intermediate protein and a well-known specific neural stem cell antigen. Some bone marrow stem cells can generate not only blood cells but also neurons and glial cells under specific culture conditions. Furthermore, in vitro cultured bone marrow stem cells also express nestin antigen. However, it is unclear whether cord blood cells also differentiate into neural cells or not. In this study, we investigated the expression of nestin on human cord blood monocytes (HCMNCs) and we discuss the relevance of this finding upon future therapeutic applications of HCMNCs in neurological diseases. METHODS: HCMNCs were prepared from normal placenta after full-term normal delivery. Immunocytochemical staining and reverse transcriptase polymerase chain reaction (RT-PCR) for nestin and CD133 antigen were performed to confirm nestin and CD133 antigen expression in the HCMNCs. RESULTS: Some nestin expressing HCMNCs were found. Immunocytochemical staining showed that some of the blood stem cell marker CD133 expressing cells co-expressed nestin. RT-PCR demonstrated nestin and CD133 mRNA in HCMNCs, but not in adult blood monocytes. Approximately, 60 +/- 8% of CD133 expressing cells expressed nestin. CONCLUSION: In the present study, we found that more than 60% of CD133 expressing HCMNCs also express nestin antigen in their cytoplasm, which supports the idea that cord blood stem cells can adopt a neuronal fate.

AC133 Antigen↗

PubMed2001

Glutamate-induced cobalt uptake reveals non-NMDA receptors in developing rat taste buds.

Non-NMDA type glutamate receptors are present in rat taste buds. However, the function of those receptors is not yet known. Developmental changes in the glutamate receptors in taste cells may provide clues to their functional role. We used a cobalt staining technique to determine at which stage in development functional non-NMDA glutamate receptors first appeared. Cobalt-stained taste bud cells first appeared in 20-day-old rats. The number of cobalt-stained cells increased with age and reached a maximum at 45 days. The shape of stained cells looked similar at all age groups. Cobalt-labeled cells appeared to be correlated with synaptic, not taste, glutamate receptors.

Aging↗

PubMed2001

Dimensional changes of dental impression materials by thermal changes.

Dental impression materials for prosthodontic treatment must be easy to use, precisely replicate of oral tissue, be dimensionally stable, and be compatible with gypsum materials. The dimensional accuracy of all materials is affected by thermal changes; impression materials shrink during cooling from mouth temperature (37 degrees C) to room temperature (23 degrees C). Five kinds of light body addition-reaction silicone impression materials [Contrast (CT), Voco Co., Germany; Examix (EM), GC Co., Japan; Extrude (EX), Kerr Co., USA; Imprint II (IM), 3M Co., USA; Perfect (PF), Handae Chemical, Korea] were tested by making cylindrical specimens (6 mm diameter and 12 mm height). The thermal expansion of the impression materials was measured with a thermomechanical analyzer (TMA 2940, TA Instruments, USA) between 23-37 degrees C. Data were analyzed via the Mann-Whitney Usage Test. To simulate actual dental impressions, tooth and tray shapes were modeled to measure the linear shrinkage of impression materials at anterior and posterior locations. The thermal expansion of impression materials tested decreased as follows: CT >or= PF >or= EM >or= EX >or= IM (p < 0.05). The anterior region changed more than the posterior region for the same impression materials. The dimensional changes averaged more than 40 microm in the anterior region, but less than 40 microm in the posterior region for all materials. Thermal expansion coefficients of some impression materials were significantly different from each other (p < 0.05), and the anterior region had more dimensional change than the posterior region for the same impression materials.

Dental Impression Materials↗

PubMed2001

Research on annihilation of cancer cells by glass-ceramics for cancer treatment with external magnetic field. I. Preparation and cytotoxicity.

Ferrimagnetic glass-ceramics were prepared as a heating mediator for hyperthermia in cancer treatment. We prepared glasses in the system 40Fe2O3-30CaO-30SiO2 and precipitated ferrimagnetic crystallites through controlled two-step heat treatment. To improve the heating capability of ferrimagnetic crystallites, i.e., magnetite, generation of other crystalline phases should be prohibited. The addition of each 1% of P2O5 and B2O3 led to lowering the crystallization temperature of magnetite, which was useful to suppress the other crystalline formation. The maximum nucleating and crystal growth rates were 20.47 x 10(6)/mm2 x s at 690 degrees C and 8.125 nm/min(0.5) at 940 degrees C, respectively. After nucleation at 690 degrees C for 60 min prior to crystal growth at 940 degrees C for 2 h, samples exhibited the following properties: crystallite size of 90.5 nm, the maximum volumetric fraction of 31.1%, and saturation magnetization of 100 emu/cm2. The coercive forces were ranged between 382.0 and 388.2 Oe in all heat-treatment conditions. As a result of a preclinical evaluation of biocompatibility by agar diffusion test with L929 cells, both as-quenched and heat-treated glasses could be biocompatible.

Bone Substitutes↗

PubMed2001

Studies on the possible mechanisms of protective activity against alpha-amanitin poisoning by aucubin.

Aucubin, an iridoid glucoside, was investigated to determine whether it has a stimulating effect on alpha-amanitin excretion in alpha-amanitin intoxicated rats, and whether there is binding activity to calf thymus DNA. High-performance liquid chromatography (HPLC) analysis of alpha-amanitin in rat urine allowed quantitative measurement of the alpha-amanitin concentration with a detection limit of 50 ng/ml. In this system, a group treated with both alpha-amanitin and aucubin showed that alpha-amanitin was excreted about 1.4 times faster than in the alpha-amanitin only treated group. Our previous results showed that the toxicity of alpha-amanitin is due to specific inhibition of RNA polymerase activity and the resultant blockage of the synthesis of certain RNA species in the nucleus. However, no significant activity change on RNA polymerase from Hep G2 cells was observed when aucubin was treated with alpha-amanitin at any concentration tested. Nevertheless, aucubigenin inhibited both DNA polymerase (IC50, 80.5 microg/ml) and RNA polymerase (IC50, 135.0 microg/ml) from the Hep G2 cells. The potential of both alpha-amanitin and aucubin to interact with DNA were examined by spectrophotometric analysis. Alpha-Amanitin showed no significant binding capacity to calf thymus DNA, but aucubin was found to interact with DNA, and the apparent binding constant (Kapp) and apparent number of binding sites per DNA phosphate (Bapp) were 0.45 x 10(4) M(-1) and 1.25, respectively.

Amanitins↗

PubMed2001

A study of the effects of chewing patterns on occlusal wear.

The chewing cycle is a functional movement, closely related to occlusion, the neuromuscular system and the central nervous system. Although actual chewing paths are complicated and vary from individual to individual, there are two typical patterns. One is more vertical in nature and is similar to a chopping movement. The other is a more lateral type that is similar to a grinding movement. The purpose of this study was to evaluate the effects of chewing patterns on occlusal wear. Fifteen subjects exhibiting a chopping-chewing pattern and 15 subjects exhibiting a grinding-chewing pattern were selected using a jaw tracking device. The occlusal wear values, obtained by both ordinal and Woda's arbitrary scales, and frequencies of non-working facets were calculated for each group. The occlusal wear values in all teeth and in each segment, obtained by the use of the ordinal scale did not vary significantly between the chopping and the grinding type group. However, the occlusal wear values of the grinding type group in all teeth and in posterior teeth segments, obtained by the use of Woda's arbitrary scale, were significantly greater than those of the chopping type group. Frequencies of non-working facets in posterior teeth showed no significant differences between the groups.

Adult↗

PubMed2001

Current medication choices in juvenile rheumatoid arthritis II--update of a survey performed in 1993.

The documentation of treatments used for Juvenile Rheumatoid Arthritis (JRA) is important to allow for the evaluation of practice patterns for future outcome studies. A survey of nine pediatric rheumatologists was performed between September 1999 and February 2000. Each of the physicians prospectively recorded demographic and treatment information on consecutively sampled JRA patients (n=395). Pauciarticular onset JRA was present in 46%, polyarticular onset JRA in 35%, and systemic onset JRA in 19% of the children. Naproxen was the most frequently prescribed medication (55% of the patients), followed by methotrexate (MTX), which was used in 39% of the patients. Folic acid supplementation (1 mg/day) was provided to 69% of the patients treated with MTX. Etanercept was used in 11% of the children. Eleven percent of the patients received corticosteroids, and 13% of children on corticosteroids took calcium supplements. Uveitis was present in 8% and had a chronic course in 79% of those cases. Although systemic medications were used in 50% of the children with uveitis to control eye inflammation, severe damage to the eyes developed in 30% of them. Fourteen percent of the patients required gastroprotective medications. Compared with findings of a similar survey performed in 1993, there was no significant change in the frequency of use of naproxen, but nabumetone is now more often prescribed, and COX-2 inhibitors have been introduced in the therapy of JRA. Changes among second-line agents used for JRA have also occurred, although there was no change in the frequency of use of MTX or corticosteroids. JRA continues to be a treatment challenge for the practicing pediatric rheumatologist. Patients often show incomplete response to the currently available medications. Therefore, new therapeutic agents need to be evaluated for their use in JRA, and the treatment of JRA associated uveitis especially needs to be improved.

Journal Article↗

PubMed2000

Heterogeneous effects of IL-2 on collagen-induced arthritis.

IL-2 is generally considered a pro-inflammatory cytokine that exacerbates Th1-mediated disease states, such as autoimmune arthritis. Consistent with this role for IL-2, recent studies from our laboratory demonstrate that IL-2 mRNA is markedly increased during the acute stage of collagen-induced arthritis (CIA), an animal model of rheumatoid arthritis. To further define the role of IL-2 in CIA, the levels of IL-2 protein and its receptor and the effects of IL-2 administration were analyzed during CIA. IL-2 protein and IL-2R were preferentially expressed at disease onset, compared with later stages of disease. Administration of recombinant human IL-2 (rhIL-2) at, or just before, disease onset exacerbated disease; surprisingly, rhIL-2 given before disease onset inhibited CIA, associated with reduced cellular and humoral responses to type II collagen. Determination of in vivo serum levels of Th1 and Th2 cytokines in response to rhIL-2 treatment demonstrated that IFN-gamma, but not IL-4, was markedly up-regulated in response to IL-2. In mice treated with anti-IFN-gamma Ab, both early and late IL-2 administration exacerbated CIA. Thus, IL-2 can have two opposite effects on autoimmune arthritis, a direct stimulatory effect and an indirect suppressive effect that is mediated by IFN-gamma.

Acute Disease↗

PubMed2000

On the mechanism of protection of distal joints after local gene transfer in collagen-induced arthritis.

Considerable interest has been generated by the observation that adenovirus-mediated gene delivery to a single arthritic joint results in suppression of arthritis in distal joints associated with the presence of small numbers of transduced cells in distal joints. It has been proposed that this is mediated by trafficking of transduced cells from the injected to distal joints. There are, however, alternative explanations that have not been explored, including the possibility that transgene protein or infectious virions circulate to distal sites. To investigate these possibilities, a replication-incompetent adenovirus encoding viral IL-10 (vIL-10) was administered to naive mice and to mice with collagen-induced arthritis by intraarticular, periarticular, or intravenous injection. In all cases, the ability to protect distal joints correlated with serum levels of vIL-10 protein. After intraarticular or intravenous injection, vIL-10 cDNA could be detected not only in distal joints, but also in the liver, which is the major target of circulating adenovirus, demonstrating that adenovirus circulating through the bloodstream is taken up by the joint tissue. Periarticular administration of adenovirus, which resulted in lower serum levels of vIL-10, protected only the injected paws and failed to induce trafficking immunoregulatory cells capable of suppressing distal disease. These observations suggest that circulating vIL-10 protein is the major mediator of distal protection. The presence of small numbers of transduced cells at distal sites can be accounted for by transduction of distal synovium after entry of adenovirus virions into the circulation.

Adenoviridae↗

PubMed2000

Glutamate-induced cobalt uptake reveals non-NMDA receptors in rat taste cells.

Taste receptor cells are chemical detectors in the oral cavity. Taste cells form synapses with primary afferent neurons that convey the gustatory information to the central nervous system. Taste cells may also synapse with other taste cells within the taste buds. Furthermore, taste cells may receive efferent connections. However, the neurotransmitters at these synapses have not been identified. Glutamate, a major excitatory neurotransmitter in other sensory organs, might act at synapses in taste buds. We used a cobalt staining technique to detect Ca(2+)-permeable glutamate receptors in taste buds and thus establish whether there might be glutamatergic synapses in gustatory end organs. When 500 microm slices of foliate and vallate papillae were briefly exposed to 1 mM glutamate in the presence of CoCl(2), a subset of spindle-shaped taste cells accumulated Co(2+). Cobalt uptake showed concentration-dependency in the range from 10 microm to 1 mM glutamate. Interestingly, higher glutamate concentrations depressed cobalt uptake. This concentration-response relation for cobalt uptake suggests that synaptic glutamate receptors, not receptors for glutamate taste, were activated. Sensory axons and adjacent non-sensory epithelium were not affected by these procedures. Glutamate-stimulated cobalt uptake in taste cells was antagonized by the non-NMDA receptor antagonist CNQX. Depolarization with 50 mM K(+) and application of NMDA (300 microM) did not increase the number of stained taste cells. This pharmacological characterization of the cobalt uptake suggests that non-NMDA receptors are present in taste cells. These receptors might be autoreceptors at afferent synapses, postsynaptic receptors of a putative efferent system, or postsynaptic receptors at synapses with other taste cells.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2000

Viral IL-10 and soluble TNF receptor act synergistically to inhibit collagen-induced arthritis following adenovirus-mediated gene transfer.

Viral IL-10 (vIL-10) and soluble TNF receptor (sTNFR) are anti-inflammatory proteins that can suppress collagen-induced arthritis (CIA). These and related proteins have shown efficacy in the treatment of human rheumatoid arthritis; however, neither alone is able to completely suppress disease. Furthermore, they have short half-lives, necessitating frequent administration. To determine the ability of these proteins to act synergistically following gene transfer, arthritis was induced in DBA/1 male mice by immunization with type II collagen on days 0 and 21. Mice were injected i.v. either before disease onset (day 20) or after disease onset (day 28) with 1010 particles of adenovirus encoding vIL-10, a soluble TNF receptor-IgG1 fusion protein (sTNFR-Ig), a combination of both vectors, or a control vector lacking a transgene. Significant synergism was observed with the combination of vIL-10 and sTNFR-Ig, with a substantial reduction in both the incidence and severity of disease as well as inhibition of progression of established disease. sTNFR-Ig alone had no effect on CIA. vIL-10 alone inhibited disease when given before disease onset, but had minimal effect on established disease. Both proteins inhibited spleen cell proliferation and IFN-gamma secretion in response to stimulation with type II collagen, but only vIL-10 reduced the synovial mRNA levels of the proinflammatory cytokines IL-1beta, TNF-alpha, and IL-6. These findings demonstrate that vIL-10 and sTNFR-Ig act synergistically in suppressing CIA and suggest that gene transfer offers a potential therapeutic modality for the treatment of arthritis.

Adenoviridae↗

PubMed2000

Effect of external stresses on calcium phosphate glass investigated by IR spectroscopy.

The effect of external stress on calcium phosphate glasses was investigated because they experience high stress in practical uses such as mastication. In order to understand the structural change of calcium phosphate glasses caused by an applied stress, the IR reflection peak shift of the phosphate structural band of the calcium phosphate glass fiber due to a bending stress was measured. The peak shift represents the change of the P-O-P bond angle. The IR reflection peak of the phosphate structural bands near approximately 1300 and approximately 910 cm(-1) shifted to a higher wavenumber under tensile stress and to a lower wavenumber under compressive stress when calcium phosphate fiber with a uniform structure was employed. This indicates that the P-O-P bond angle increases under tensile stress and decreases under compressive stress. The extents of both peak shifts were larger with a lower [corrected] Ca/P ratio than with a higher [corrected] Ca/P ratio. Therefore, phosphate glass with a higher Ca/P ratio is expected to withstand loads under external stress.

Biocompatible Materials↗

PubMed2000

Effect of iron state on crystallization and dissolution in Fe2O3-CaO-SiO2 glasses.

The possibility of iron-containing glasses as thermoseeds for hyperthermia of bone tumor was reported previously. There is, however, no report about the effect of iron state on the crystallization of magnetite and the resultant properties. The iron states were determined by Mössbauer spectroscopy in Fe2O3-CaO-SiO2 system. It was found that the higher CaO content interrupts the crystallization of magnetite crystallites as well as the oxidation of iron, that is, the transformation from Fe3+ to Fe2+. A sample containing large amounts of Fe2+ showed the faster increment of temperature when the alternating magnetic field was applied. In order to use the thermoseed for a hyperthermia, we can say that the composition with low CaO content is most useful.

Journal Article↗

PubMed2000

A study on the mandibular movement of anterior openbite patients.

The purpose of this study was to compare the mandibular movements of anterior openbite patients using those of normal bite (angle class I) patients, to ascertain which components of mandibular movement are different in the two groups, and to use this information for occlusal treatment. The Saphon Visi-trainer Model 3 and the Denar Pantronic were used to record mandibular movement and a Pantronic survey was performed using an arbitrary hinge axis, according to manufacturer's instructions. The subjects were 43 adults and included 28 subjects presenting with acceptable normal occlusion (angle class I) with no sign of TM dysfunction syndrome (TMD) and 15 subjects with anterior openbite with no anterior guidance. In the anterior openbite group, the average anterior and lateral condylar inclination, maximum opening and the distance between the intercuspal position with retruded contact position distance (anterior-posterior) were significantly lower than normal. The results suggest that in openbite patients the condyle inclination is flatter and the function of the TMJ is more restricted than in the mandibular movements of the normal group. It is hoped that these results will be useful for the correction of the anterior openbite condition.

Adolescent↗