Biomedical subjects

M K Kim

Publications and source records attributed to M K Kim.

At least 19 recordsLinked to original sources

PubMed2003

Release of ciprofloxacin from poloxamer-graft-hyaluronic acid hydrogels in vitro.

Recently, in situ gel formation has extensively been studied to enhance ocular bioavailability and duration of the drug activity. In this study, we report grafting of poloxamer onto the hyaluronic acid for application of tissue engineering oriented ophthalmic drug delivery system. Graft copolymers were prepared by coupling mono amine-terminated poloxamer (MATP) with hyaluronic acid (HA) backbone using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxylsuccinimide (NHS) as coupling agents. The coupling of MATP with HA was clarified by 1H NMR and FT-IR spectroscopy. The gelation temperature of graft copolymers was dependent on the content of HA and the concentration of poloxamer. From drug release studies in vitro, ciprofloxacin was sustainedly released from the poloxamer-g-hyaluronic acid hydrogel due to the in situ gel formation of the copolymer and viscous properties of HA.

Ciprofloxacin↗

PubMed2003

Phase imaging without 2pi ambiguity by multiwavelength digital holography.

We present a phase-imaging method with an axial range that can in principle be arbitrarily large compared to the wavelength and does not involve the usual phase unwrapping by detection of phase discontinuity. The method consists of the generation and combination of two phase maps in a digital holography system by use of two separate wavelengths. For example, we reconstructed the surface of a spherical mirror with approximately 10-nm axial resolution and an axial range of approximately 3 microm.

Journal Article↗

PubMed2003

A fatal case of Vibrio vulnificus meningoencephalitis.

The objective of this paper is to report a rare case of Vibrio vulnificus presenting as meningoencephalitis without a wound infection. Vibrio vulnificus is capable of causing severe and often fatal infections in susceptible individuals. It commonly causes necrotizing wound infections, primary septicemia, and gastroenteritis. A 69-year-old man had meningoencephalitis with lesion on the red nucleus, substantia nigra, basal ganglia, and dentate nucleus as the initial clinical manifestation of a V. vulnificus infection. This is the first case of V. vulnificus infection in which MRI demonstrated the involvement of deep nuclei of the brain.

Aged↗

PubMed2002

The effect of a disrupted yhjQ gene on cellular morphology and cell growth in Escherichia coli.

The 5' upstream region of the cellulose synthase operon ( bcs operon) has been isolated by cloning from Escherichia coli. A gene encoding YhjQ is located 1.0 kb upstream of the bcs operon in E. coli. The function of YhjQ remains unknown. Insertional inactivation of the yhjQ gene causes abnormal cell division, resulting in incomplete partition of the chromosome and filamentous cells of various sizes. These results suggest that the product of yhjQ may affect normal doubling and cellular morphology.

Cell Cycle↗

PubMed2002

Specimen block counter-staining for localization of GUS expression in transgenic arabidopsis and tobacco.

A simple counter-staining procedure has been developed for comparative beta-glucuronidase (GUS) expression and anatomical localization in transgenic herbaceous arabidopsis and tobacco. This protocol provides good anatomical visualization for monitoring chimeric gene expression at both the organ and tissue levels. It can be used with different histochemical stains and can be extended to the study of woody species. The specimens are paraffin-embedded, the block is trimmed to reveal internal structure, safranin-O staining solution is briefly applied to the surface of the block, then washed off and, after drying, a drop of immersion oil is placed on the stained surface for subsequent photographic work. This gives tissue counter-staining with good structural preservation without loss of GUS staining product; moreover, sample observation is rapid and efficient compared to existing procedures.

Arabidopsis↗

PubMed2002

Relationships of urinary phyto-oestrogen excretion to BMD in postmenopausal women.

OBJECTIVE: Phyto-oestrogens are plant compounds with both oestrogenic and anti-oestrogenic properties. However, it is not known whether natural phyto-oestrogens are beneficial or harmful in human osteoporosis. This study was performed to investigate the relationships between urinary phyto-oestrogens and bone mineral density (BMD) in Korean postmenopausal women. DESIGN: The subjects were classified into osteoporotic, osteopenic and normal groups according to their BMD as defined by WHO criteria. We compared the urinary phyto-oestrogens of each group and studied whether urinary phyto-oestrogens correlate with BMD. PATIENTS: The subjects were 75 Korean postmenopausal women with ages ranging from 52 to 65 years (mean 58 +/- 1.1 years). Mean number of years after menopause was 7.3 +/- 1.3. MEASUREMENTS: Twenty-four-hour urinary phyto-oestrogens were measured by gas chromatography-mass spectrometry (GCMS) and BMD by dual-energy X-ray absorptiometry (DXA, Lunar Expert-XL, Lunar Co., WI, USA). RESULTS: In Korean postmenopausal women, urinary enterolactone (1.46 +/- 1.11 micromol/day) was lower and daidzein (2.59 +/- 3.25 micromol/day) was higher than in western women, and both levels were comparable to those in Japanese women. Daily urinary excretion of genistein and apigenin were 1.09 +/- 0.912 and 0.48 +/- 0.40 micromol/day, respectively. In subjects with osteoporosis, urinary enterolactone was lower (P < 0.05) but apigenin was significantly higher (P < 0.05) than in the controls. BMD of L2-L4 correlated positively with urinary enterolactone (r = 0.388, P < 0.01), and BMD of the femoral neck and Ward's triangle correlated positively with urinary enterolactone (r = 0.271, P < 0.05 and r = 0.322, P < 0.05) but negatively with apigenin (r = -0.412, P < 0.01 and r = -0.395, P < 0.01). By multiple stepwise regression, the variables associated with spinal BMD were age, the amount of urinary apigenin and body mass index (BMI). The variables associated with femoral neck BMD were age and urinary apigenin. CONCLUSIONS: From these results, we conclude that urinary phyto-oestrogens, especially enterolactone and apigenin, are related to BMD in Korean postmenopausal women. Our results also suggest the possibility that phyto-oestrogens have differential effects on bone density. Further studies are needed to clarify the exact biological roles of phyto-oestrogenic components on bone metabolism.

4-Butyrolactone↗

PubMed2002

Analysis of errors in medical rapid prototyping models.

Rapid prototyping (RP) is a relatively new technology that produces physical models by selectively solidifying UV-sensitive liquid resin using a laser beam. The technology has gained a great amount of attention, particularly in oral and maxillofacial surgery. An important issue in RP applications in this field is how to obtain RP models of the required accuracy. We investigated errors generated during the production of medical RP models, and identified the factors that caused dimensional errors in each production phase. The errors were mainly due to the volume-averaging effect, threshold value, and difficulty in the exact replication of landmark locations. We made 16 linear measurements on a dry skull, a replicated three-dimensional (3-D) visual (STL) model, and an RP model. The results showed that the absolute mean deviation between the original dry skull and the RP model over the 16 linear measurements was 0.62 +/- 0.35 mm (0.56 +/- 0.39%), which is smaller than values reported in previous studies. A major emphasis is placed on the dumb-bell effect. Classifying measurements as internal and external measurements, we observed that the effect of an inadequate threshold value differs with the type of measurement.

Algorithms↗

PubMed2002

Comparative experiments for in vivo fibroplasia and biological stability of four porous polymers intended for use in the Seoul-type keratoprosthesis.

AIMS: To evaluate in vivo fibroplasia and biological stability of porous polymers intended for use in the Seoul-type keratoprosthesis (S-KPro). METHODS: Four porous polymers (polypropylene, two kinds of polyethylene terephthalate (PE70 and PE50), and polyurethane) were investigated. Discs of polymers were inserted into the corneal stroma of rabbits for a 2 and 5 month period. Corneal oedema and neovascularisation were evaluated. The fibroplasia and collagen deposition were examined under light and transmission electron microscopy. S-KPros, whose skirt was made of four types of polymer, were implanted into the rabbits' eyes. The retention time and complications were evaluated. RESULTS: Neovascularisation and corneal oedema were found in all of the disc inserted eyes, but the corneal oedema subsided within 2 months in most of the eyes. The mean number of fibroblasts increased significantly in polypropylene and PE50 disc inserted eyes compared with polyurethane disc inserted eyes. Plentiful collagen deposition was also found in both polypropylene and PE50 disc inserted eyes. Mean retention time in the polypropylene SK-Pro implanted eyes was longer than that of the other eyes (20.7 weeks). The PE70 skirt induced corneal melting around the prosthesis. CONCLUSION: Polypropylene encourages fibroblast ingrowth and shows good biological stability when used as a skirt material in S-KPro.

Animals↗

PubMed2002

Clearance of quinupristin-dalfopristin (Synercid) and their main metabolites during continuous veno-venous hemofiltration (CVVH) with or without dialysis.

BACKGROUND: Quinupristin-dalfopristin (Q/D) is often utilized in critically ill patients, some of whom require CVVH. This study was undertaken to determine the clearance of O/D and their main active metabolites (RPR 100391, RP 69012, RP 12536) via CVVH in the swine model. METHODS: Q/D 7.5 mg/kg was intravenously administered over 0.5 h to 12 swine after induction of acute renal failure by ligation of the renal arteries. At 0.5 h post injection, the CVVH procedure was initiated and continued for 8 hours at the following pump rates: (1)100 mL/min, (2)180 rnL/min, and (3)100 mL/min with dialysis (flow rate: 1 L/h). Blood and ultrafiltrate samples were collected at 1 h intervals and assessed by a validated HPLC method. RESULTS: Plasma analysis suggests rapid metabolism to the main active metabolites which are appreciably cleared as demonstrated by high clearance and sieving coefficient estimates. Mean clearance estimates for RP 69012, RP 100391, and RP 12536 are 729, 777, and 578 mL/h in the 100 mL/min CVVH group, 772, 785, 685 mL/min in the 180 mL/min CVVH group, and 753, 791, 616 mL/min in the 100 mL/min CVVH group with 1 L/h dialysis, respectively. CONCLUSION: These data reveal that Q/D is rapidly metabolized and the metabolites are cleared to a large extent via CVVH. Due to the considerable contribution of the metabolites to overall in vivo activities, additional studies are required to fully quantify their removal before final dosage modifications for patients undergoing CVVH can be recommended.

Animals↗

PubMed2001

The cytoplasmic domain of FcgammaRIIA (CD32) participates in phagolysosome formation.

Signaling motifs located within the cytoplasmic domain of certain receptors contribute to lysosome fusion. Most studies have described lysosome fusion with respect to endocytic receptors. Phagolysosome fusion has not been extensively studied. To test the hypothesis that the tail of FcgammaRIIA participates in phagolysosomal fusion, a "reverse" genetic complementation system was used. It was previously shown that complement receptor type 3 (CR3) can rescue the phagocytic activity of a mutant FcgammaRIIA lacking its cytoplasmic domain (tail-minus form). This system has allowed us to study Fcgamma receptor-dependent phagocytosis and phagolysosome fusion in the presence and absence of the cytoplasmic domain of FcgammaRIIA. Fluorescent dextran was used to label lysosomes. After target internalization, wild-type FcgammaRIIA-mediated phagolysosome formation was observed as indicated by colocalization of fluorescent dextran and the phagosome. In addition, when studying mutants of FcgammaRIIA containing a full-length cytoplasmic tail with the 2 ITAM tyrosines mutated to phenylalanine, (1) phagocytosis was abolished, (2) CR3 restored phagocytosis, and (3) lysosomal fusion was similar to that observed with the wild-type receptor. In contrast, in the presence of CR3 and the tail-minus form of FcgammaRIIA, internalized particles did not colocalize with dextran. Electron microscopy revealed that the lysosomal enzyme acid phosphatase colocalized with immunoglobulin G-coated targets internalized by wild-type FcgammaRIIA but not by tail-minus FcgammaRIIA and CR3. Thus, the tail of FcgammaRIIA contributes to phagolysosome fusion by a mechanism that does not require a functional ITAM sequence.

Acid Phosphatase↗

PubMed2001

5,6-Diphenylpyridazine derivatives as acyl-CoA:cholesterol acyltransferase inhibitors.

Alkyl-5,6-diphenylpyridazine derivatives combining several main features of ACAT inhibitors, such as a long alkyl side chain linked to a heterocycle and the o-diphenyl system, were synthesized and tested. Moreover, modeling studies on representative terms were performed. Some compounds displayed ACAT inhibition in the micromolar range, both on the enzyme isolated from rat liver microsomes and in cell-free homogenate of murine macrophages.

Animals↗

PubMed2001

Cloning and characterization of an intracellular isoamylase gene from Pectobacterium chrysanthemi PY35.

The gene encoding an intracellular isoamylase from the Pectobacterium chrysanthemi PY35 was cloned in Escherichia coli DH5alpha and sequenced. The isoamylase gene (amyX) had an open reading frame of 1974 bp encoding 657 amino acid residues with a calculated molecular weight of 74,151 Da. The molecular weight of the enzyme was also estimated to be 74 kDa by activity staining of a SDS-PA gel. Isoamylase from P. chrysanthemi PY35 had 59% pairwise amino acid identity with glycogen debranching enzyme from E. coli and contained the four regions conserved among all amylolytic enzymes. The isoamylase was optimally active at pH 7 and 40 degrees C. AmyX hydrolyzed alpha-1,6-glycosidic linkages of amylopectin, while did not hydrolyze alpha-1,4-glycosidic linkages of amylose.

Amino Acid Sequence↗

PubMed2001

Ectopic expression of tyrosine hydroxylase in Zebrin II immunoreactive Purkinje cells in the cerebellum of the ataxic mutant mouse, pogo.

The pogo mouse is a new ataxic autosomal recessive mutant that arose in an inbred strain (KJR/MsKist) derived from a Korean wild mouse. The phenotype includes difficulty in maintaining normal posture and the inability to walk straight. Several previous studies have associated inherited ataxia with the ectopic expression of tyrosine hydroxylase (TH) in Purkinje cells. Therefore, in the present study, the distribution of TH expression was compared with that of zebrin II in Purkinje cells of adult pogo/pogo mutant mice. In normal control littermates, tyrosine hydroxylase immunoreactivity is confined to a delicate axonal plexus ramifying through the molecular layer. In pogo/pogo, in addition to the axonal plexus, TH-immunoreactive Purkinje cells were present in all lobules of the cerebellar vermis and hemispheres, distributed as series parasagittal bands. The general pattern of expression is reproducible between individuals and symmetrical about the midline. Alternating stripes of TH expression are also seen in the hemispheres, and most Purkinje cells in the paraflocculi and flocculi are immunoreactive. In pogo/+ mice, TH-immunoreactive Purkinje cells are rare. The pattern of zebrin II expression was used to map TH immunoreactive Purkinje cells in pogo/pogo mutant mice. Double immunofluorescence labeling combining anti-zebrin II fand anti-TH showed that all TH-immunoreactive Purkinje cells are zebrin II+, but that many zebrin II+ Purkinje cells within a band do not stain with anti-TH. Taken together with the morphological changes observed in the Purkinje cell axons, this suggests that abnormal Purkinje cell function may contribute to the ataxic phenotype in pogo/pogo mice.

Animals↗

PubMed2001

Antisense DNAs as multisite genomic modulators identified by DNA microarray.

Antisense oligodeoxynucleotides can selectively block disease-causing genes, and cancer genes have been chosen as potential targets for antisense drugs to treat cancer. However, nonspecific side effects have clouded the true antisense mechanism of action and hampered clinical development of antisense therapeutics. Using DNA microarrays, we have conducted a systematic characterization of gene expression in cells exposed to antisense, either exogenously or endogenously. Here, we show that in a sequence-specific manner, antisense targeted to protein kinase A RIalpha alters expression of the clusters of coordinately expressed genes at a specific stage of cell growth, differentiation, and activation. The genes that define the proliferation-transformation signature are down-regulated, whereas those that define the differentiation-reverse transformation signature are up-regulated in antisense-treated cancer cells and tumors, but not in host livers. In this differentiation signature, the genes showing the highest induction include genes for the G proteins Rap1 and Cdc42. The expression signature induced by the exogenously supplied antisense oligodeoxynucleotide overlaps strikingly with that induced by endogenous antisense gene overexpression. Defining antisense DNAs on the basis of their effects on global gene expression can lead to identification of clinically relevant antisense therapeutics and can identify which molecular and cellular events might be important in complex biological processes, such as cell growth and differentiation.

Adenocarcinoma↗

PubMed2001

Compaction in preimplantation mouse embryos is regulated by a cytoplasmic regulatory factor that alters between 1- and 2-cell stages in a concentration-dependent manner.

Present studies were performed to investigate what factors affect the morphogenesis of preimplantation mouse embryos, and to find the action mechanism of that factor by using cytoplasm removal and its reconstitution from a different developmental stage embryo. Half (HP group) or one-third of cytoplasm (TP group) was removed from 1-cell mouse embryos by micromanipulation, and their morphogenesis and genome expression were compared with sham-operated embryos (SP group). The compaction and blastocoel formation of embryos in both the HP and TP groups were accelerated in time and cell stage when compared with those of the SP group. However, the total activity and time of RNA synthesis, and gene expression of ZO-1alpha+ isoform were not different. To change the cytoplasm composition without altering the nucleus/cytoplasmic ratio, half a 1-cell embryo with both pronuclei was reconstituted with the half enucleated cytoplasm of 1-cell embryo (P + P group), 2-cell (P + 2 group) or 4-cell (P + 4 group) by electrofusion. Embryonic compaction, timing of RNA synthesis, and stage-specific gene expression of the ZO-1alpha(+) isoform in the P + 2 and P + 4 groups were accelerated in time and cell stage than that in the P + P group, but not different between the P + 2 and P + 4 groups. In addition, a blastomere of 2-cell embryo was reconstituted with the enucleated cytoplasm of 1-cell embryo (2 + P group) or 2-cell (2 + 2 group) in equal volume by electrofusion. Also, the karyoplast of 2-cell was fused with the enucleated 1-cell embryo (2 + PP group). Embryonic development, total activity of RNA synthesis, and gene expression of the ZO-1alpha(+) isoform of embryos in the 2 + P and 2 + PP groups were delayed when compared with those of the 2 + 2 group. Also, the phenomena of compaction and blastocoel formation were delayed in the development time and cell stage. From these results, the nucleus/cytoplasm ratio was found to have no direct effect on the regulation of embryonic morphogenesis, although it accelerated compaction and blastocoel formation. However, cytoplasmic factors that altered between 1- and 2-cell stages regulate embryonic morphogenesis, especially compaction, of preimplantation mouse embryos in concentration-dependent manner.

Animals↗

PubMed2001

CD99 expression is positively regulated by Sp1 and is negatively regulated by Epstein-Barr virus latent membrane protein 1 through nuclear factor-kappaB.

Epstein-Barr virus (EBV)-encoded latent membrane protein-1 (LMP1) is highly expressed in Hodgkin and Reed-Sternberg (H-RS) cells from patients with EBV-associated Hodgkin disease. It was previously demonstrated that CD99 can be negatively regulated by LMP1 at the transcriptional level, and the decreased expression of CD99 in a B lymphocyte cell line generates H-RS-like cells. In this study, detailed dissection of the CD99 promoter region was performed to search regulatory factor(s) involved in the expression of the gene. Using various mutant constructs containing deletions in the promoter region, it was revealed that the maximal promoter activity was retained on 5'-deletion to the position -137 from the transcriptional initiation site. Despite the presence of multiple putative Sp1-binding sites in the promoter region, the site located at -95 contributes heavily as a positive cis-acting element to its basal promoter activity. However, on examination of the involvement of the positive-acting Sp1-binding site of the promoter for the repressive activity of LMP1, it appeared to be dispensable. Instead, the repressive effect was mapped to the nuclear factor (NF)-kappaB activation domains in the cytoplasmic carboxyl terminus of LMP1 despite the absence of the NF-kappaB consensus sequences in the CD99 promoter region. Furthermore, the decreased CD99 promoter activity by LMP1 was markedly restored when NF-kappaB activity was inhibited. Taken together, these data suggest that Sp1 activates, whereas LMP1 represses, transcription from the CD99 promoter through the NF-kappaB signaling pathway, and they might aid in the understanding of the molecular mechanisms of viral pathogenesis in EBV-positive Hodgkin disease. (Blood. 2001;97:3596-3604)

12E7 Antigen↗

PubMed2001

Formulation of a reservoir-type testosterone transdermal delivery system.

A reservoir-type transdermal delivery system of testosterone (TS) was developed using an ethanol/water (70:30) cosolvent system as the vehicle. The maximum permeation rate achieved by 70% (v/v) of ethanol was further increased from 2.69 to 47.83 microg/cm(2)/h with the addition of 1.0% dodecylamine as the skin permeation enhancer. The permeation rate of TS through the ethylene vinyl acetate (EVA) membrane was observed to increase as the vinyl acetate content in the copolymer increased. Addition of 1.0% (w/w) gelling agent, hydroxypropyl methlycellulose (HPMC), in the reservoir formulation resulted in desirable rheological properties with an insignificant effect on the skin permeation rate of TS. Thus, a new transdermal delivery system for TS was formulated using EVA membrane coated with a pressure-sensitive adhesive (Duro-Tak 87-2510) and HPMC as a gelling agent. This experimental patch showed comparable plasma concentration profiles in the in vivo study when compared with a commercial product, Androderm(R). Moreover, the results suggested the possibility of further enhancing the permeation rate of TS by controlling the composition of the reservoir formulation.

Administration, Cutaneous↗

PubMed2001

The role of peripheral N-methyl-D-aspartate receptors in Freund's complete adjuvant induced mechanical hyperalgesia in rats.

We investigated the role of excitatory amino acid receptors in mechanical hyperalgesia induced by subcutaneous injection of Freund's complete adjuvant (FCA) into the rat hind paw. In normal rats, an intraplantar (i.pl.) injection of L-glutamate, but not of D-glutamate (3 pmol/0.1 ml each) produced a mechanical hyperalgesia in the hind paw with a lowered paw-withdrawal threshold to pressure. In rats that developed mechanical hyperalgesia associated with inflammation in the hind paw following i.pl. injection of FCA (0.15 ml), the injection of N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801 (1 pmol/0.1 ml) into the inflamed paw increased the paw pressure threshold. On the other hand, the injection of non-NMDA receptor antagonist, 6-cyano-7-nitroqiunoxaline-2,3-dione (CNQX, 10 pmol/0.1 ml) into the inflamed paw had no effect on FCA-induced lowering of the paw pressure threshold. The results suggest that NMDA, but not non-NMDA receptors play a substantial role in mediating the development of mechanical hyperalgesia induced in the inflamed paw following i.pl. FCA injection.

6-Cyano-7-nitroquinoxaline-2,3-dione↗