Acceleration of an enzymatic reaction in a microchip.
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Ampyrone↗
Biomedical subjects
H B Kim
Publications and source records attributed to H B Kim.
Emission and metal- and ligand-centered-redox characteristics of the hexarhenium(III) clusters trans- and cis-[Re6(mu 3-S)8Cl4(L)2]2-, where L is a pyridine derivative or pyrazine.
Preparations of a series of face-capped octahedral hexarhenium(III) clusters having two N-heterocyclic ligands, [Bu4N]2[trans-[Re6(mu 3-S)8Cl4(L)2]] (Bu4N+ = tetra-n-butylammonium cation; L = pyrazine (1a), 4,4'-bipyridine (3a), 4-methylpyridine (5a), 4-(dimethylamino)pyridine (6a)) and their cis analogues (1b, 3b, 5b, and 6b, respectively), and their electrochemical and photophysical properties have been reported. An X-ray crystal structure determination has been carried out for 1a to confirm the trans configuration (C40H80N6S8Cl4Re6, orthorhombic, space group Cmca (No. 64), a = 19.560(5) A, b = 19.494(4) A, c = 18.592(4) A, beta = 115.76(2) degrees, Z = 4). The redox potential of the reversible ReIII6/ReIII5ReIV process of these complexes and previously reported [Bu4N]2[trans- and cis-[Re6(mu 3-S)8Cl4(4-cyanopyridine)2]] (2a and 2b, respectively) and [Bu4N]2[trans- and cis-[Re6(mu 3-S)8Cl4(pyridine)2]] (4a and 4b, respectively) in acetonitrile depends linearly on the pKa of the N-heterocyclic ligands, with the potentials being more negative with basic ligands. The ligand-centered-redox waves for 1a, 1b, 2a, and 2b were observed as split waves (delta E1/2 = 90-140 mV), the extent of the splitting being larger for the cis isomer and largest for the pyrazine complexes. Electronic interaction between the two ligands through the [Re6(mu 3-S)8]2+ core has been suggested. The second ligand-reduction wave was also observed for 3a and 3b, the potential being shifted positively to coalesce with the first reduction wave on addition of the weak proton donor imidazole. This is accounted for by the proton-coupled redox reaction at the free pyridyl site of the 4,4'-bipyridine ligands. All of the complexes show luminescence in acetonitrile at room temperature. While the complexes of pyridine and 4-methylpyridine show photophysical characteristics (lambda em 740-750 nm, phi em 0.031-0.057, tau em 4.2-6.2 microseconds) similar to those (770 nm, 0.039, and 6.3 microseconds, respectively) of [Re6(mu 3-S)8Cl6]4-, emissions of other complexes are significantly weak with lambda em, phi em, and tau em values in the ranges 763-785 nm, 0.0010-0.0017, and 0.013-0.029 microsecond, respectively. Suggestions are given for the excited states localized on the cluster core and the ligand pi* orbitals.
Journal Article↗
Effect of mitomycin-C on posterior capsule opacification in rabbit eyes.
PURPOSE: To determine whether mitomycin-C can inhibit posterior capsule opacification (PCO) without causing ocular toxicity. SETTING: Yonsei Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea. METHODS: Mitomycin-C dissolved in sodium hyaluronate (0.2 cc of 0.2 mg/mL) was injected into the empty capsular bag for 3 minutes after endocapsular phacoemulsification in rabbit eyes. Three months after surgery, the obstruction rate of visible light caused by PCO was measured using an optical power meter. RESULTS: The mean obstruction rate of visible light was 81.0% +/- 8.3% (SD) in the control group in which sodium hyaluronate without mitomycin-C was used, 30.5% +/- 10.1% in the group in which mitomycin-C was dissolved in sodium hyaluronate, and 71.9% +/- 6.8% in the group in which mitomycin-C was dissolved in a balanced salt solution. Statistically significant differences were found among all 3 groups. CONCLUSIONS: Our results suggest that the application of mitomycin-C dissolved in sodium hyaluronate effectively reduces PCO in rabbit eyes.
Adjuvants, Immunologic↗
Comparison of tear secretion and tear film instability after photorefractive keratectomy and laser in situ keratomileusis.
PURPOSE: To evaluate and compare tear secretion and tear film instability following photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). SETTING: Department of Ophthalmology, Yonsei University School of Medicine, Seoul, Korea. METHODS: In a prospective study, 36 eyes (21 patients) had PRK and 39 eyes (25 patients) had LASIK to correct myopia. Tear secretion and tear film instability were tested preoperatively and 3 and 6 months postoperatively using Schirmer test values, tear breakup time (BUT) scores, and tear osmolarity. RESULTS: Six months after surgery, the change in Schirmer test values from preoperative levels was -14.57% +/- 6.39% (SD) in the PRK eyes and -23.40% +/- 5.94% in the LASIK eyes and the change in BUT scores, -12.54% +/- 8.28% and -18.79% +/- 13.01%, respectively. The change in tear osmolarity was 14.95% +/- 6.46% and 35.63% +/- 8.51%, respectively. CONCLUSIONS: The decrease in tear secretion was greater after LASIK than after PRK at 6 months. Proper treatment of dry eye is required after LASIK and PRK, particularly in the LASIK postoperative period.
Adult↗
Conductimetric membrane strip immunosensor with polyaniline-bound gold colloids as signal generator.
For point-of-care examination, an immuno-chromatographic assay system based on conductimetric detection was investigated by utilizing, as signal generator, colloidal gold with polyaniline bound on the metal surface. Although the gold is a widely used label for antibodies to produce colorimetric signals, the tracer does not lend itself for a suitable electric conduction along the gold particles due to the presence of protein barriers (e.g. immunoglobulin and blocking agent) against electron transfer. To overcome this problem, we introduced a conducting polymer, for instance, polyaniline, as a conductivity-modulating agent on the gold surface after immobilizing an antibody specific to human albumin used as model analyte. This novel signal generator amplified the conductimetric signal 4.7 times compared with the plain gold, and the signal was also maximum 2.3-fold higher than that from the photometric system under the same analytical conditions. The latter effect resulted from an exponential pattern in the dose-response curve of the electric signal that was different from the conventional sigmoidal shape.
Aniline Compounds↗
Fetal wound repair results in scar formation in interleukin-10-deficient mice in a syngeneic murine model of scarless fetal wound repair.
BACKGROUND: Fetal dermal wound healing is characterized by minimal inflammation, restoration of normal dermal architecture, and scarless repair. The authors have shown that proinflammatory cytokines interleukin-6 (IL-6) and interleukin-8 (IL-8) are diminished during fetal wound repair. Interleukin-10 (IL-10) is an antiinflammatory cytokine that decreases production of IL-6 and IL-8. The authors hypothesized that diminished IL-6 and IL-8 and minimal inflammation may be caused by IL-10. METHODS: To test this hypothesis, the authors developed a new syngeneic murine model of fetal wound repair in which 15-day-gestation skin from either normal C57BL/6 or transgenic C57BL/6 IL-10 knockout mice was grafted to the back of the same strain adult mice. The grafts were incisionally wounded after 5 days, harvested at 1 week, and analyzed for inflammatory response and scar formation. RESULTS: Wounds in normal fetal skin grafts showed minimal inflammation and normal dermal reticular collagen pattern at the site of the wound, consistent with scarless repair. In contrast, wounds in IL-10 knockout fetal skin grafts showed significant inflammation and scar formation. CONCLUSIONS: Fetal skin grafts on adult syngeneic mice heal without inflammation or scar formation. The absence of IL-10 in fetal skin results in scar formation. Intrinsic lack of IL-10 may result in continued amplification of the inflammatory cytokine cascade, continued stimulation of fibroblasts, and abnormal collagen deposition. IL-10 is necessary for scarless wound repair to occur.
Animals↗
Intrahepatic metastasis in hepatocellular carcinoma through reversed hepatic venous flow.
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Carcinoma, Hepatocellular↗
A kinetic model for the homing and migration of prenatally transplanted marrow.
Currently little is known about the mechanisms regulating the homing and the early engraftment of prenatally transplanted hematopoietic cells due to the lack of a relevant functional assay. In this study, we have defined a reproducible kinetic profile of the homing and the early engraftment events in a murine model of prenatal stem cell transplantation. Light density mononuclear cells (LDMCs) from adult C57Pep3b and SJL/J marrow were transplanted by intraperitoneal (IP) injection into C57BL/6 fetuses (10(6) LDMCs/fetus) at 14 days of gestation. The fetuses were sacrificed at early time points (1.5 to 96 hours) after transplantation. Recipient fetal liver and cord blood were analyzed for donor cell frequency and donor cell phenotype by dual color flow cytometry. Pertinent findings included the following: (1) a triphasic kinetic profile exists after in utero hematopoietic stem cell (HSC) transplantation (homing of circulating donor cells, rapid reduction of donor cell frequency, and donor cell competitive equilibration); (2) homing to the fetal liver is nonselective and reflects the phenotypic profile of the donor population; and (3) the kinetics after the prenatal transplantation of congenic or fully allogeneic cells are identical. This model will facilitate a systematic analysis of the mechanisms that regulate the homing of prenatally transplanted hematopoietic cells.
Animals↗
Analysis of Corynebacterium glutamicum methionine biosynthetic pathway: isolation and analysis of metB encoding cystathionine gamma-synthase.
The metB gene encoding cystathionine y-synthase, the second enzyme of methionine biosynthetic pathway, was isolated from a pSL109-based Corynebacterium glutamicum gene library via complementation of an Escherichia coli metB mutant. A DNA-sequence analysis of the cloned DNA identified an open-reading frame of 1161 bp which encodes a protein with the molecular weight of 41,655 comprising of 386 amino acids. The putative protein product showed good amino acid-sequence homology to its counterpart in other organisms. Introduction of a plasmid carrying the cloned metB into the C. glutamicum resulted in a 10-fold increase in cystathionine gamma-synthase activities, demonstrating the identity of the cloned gene. The C. glutamicum metB mutant which was generated by the site-specific integration of the cloned DNA into its chromosome did not lose the ability to grow on glucose minimal medium lacking supplemental methionine. The growth rate of the mutant strain was also comparable to that of the parental strain. These data indicate that, in addition to the transsulfuration pathway, other methionine biosynthetic pathways may be present in C. glutamicum.
Amino Acid Sequence↗
Postnatal booster injections increase engraftment after in utero stem cell transplantation.
BACKGROUND: The primary barrier to clinical application of in utero hematopoietic stem cell (HSC) transplantation is limited donor cell engraftment. We hypothesized that limited engraftment was due to competition between host and donor cells for available niches. We reasoned that increased engraftment might be achieved by performing multiple transplants separated by brief intervals to allow time for formation of new niches. To test this we performed multiple transplants in a congenic combination to avoid confounding immunologic effects. MATERIALS AND METHODS: C57Pep3B (H2Kb, CD45.1) mice were used as donors of adult bone marrow and C57Bl/6 (H2Kb, CD45.2) mice were used as 14-day-gestation fetal recipients. All fetuses were injected intraperitoneally with 1 x 10(6) mononuclear cells. Boosted neonates were injected at Days 2, 4, and 7 of life with 5 x 10(6) cells. All animals were analyzed for donor cell engraftment by dual-color flow cytometry using CD45 and CD45.1 antigens. Results are reported as the mean +/- SD. Statistical analysis was performed using the two-tailed Student t test with P < 0.05 considered significant. RESULTS: Postnatally boosted animals demonstrated significantly elevated levels of donor cell engraftment (3.30 +/- 0.8%; n = 8; P < 0.00001) when compared to the control animals (0.69 +/- 0.5%; n = 9) as determined by peripheral blood analysis at 6 weeks of age. This elevated level of engraftment was stable long term. CONCLUSIONS: Our results demonstrate a significant increase in donor cell engraftment with postnatal booster injections after in utero transplantation. This supports the hypothesis that a limited number of niches may be a major component of the barrier to engraftment. It also suggests that postnatal booster injections may be a viable therapeutic strategy for improving donor cell engraftment after in utero HSC transplantation.
Aging↗
Immunochromatographic membrane strip assay system for a single-class plasma lipoprotein cholesterol, exemplified by high-density lipoprotein cholesterol measurement.
In assessing risk factors of coronary heart disease, a membrane immunochromatographic system that minimizes requirements of instrument and reagent handling was investigated by utilizing high-density lipoprotein (HDL) cholesterol (HDL-C) as model analyte. The system is composed of four functional membrane strip pads connected in sequence as follows (from the bottom): immunoseparation based on the biotin-streptavidin reaction; catalytic conversion of cholesterol to hydrogen peroxide; production of a colorimetric signal; and induction of a continuous wicking of medium. For immunochromatography, a monoclonal antibody, specific to apolipoprotein B100 that is present on the surfaces of low-density lipoproteins (LDL) and very low-density lipoproteins (VLDL), with a high binding constant (5 x 10(10) L/mol), was raised and chemically conjugated to streptavidin. The conjugate was first reacted with lipoprotein particles, and this mixture was absorbed by the capillary action into the biotin pad of the system. After being transferred by medium, immunocapture of LDL and VLDL particles onto the biotin pad took place, and in situ generation of a colorimetric signal in proportion to HDL-C occurred consecutively. The capture was selective as well as effective (minimum 88% of LDL and VLDL in clinical concentration ranges), and the detection limit of the HDL-C was far lower than 20 mg per 100 mL. The same concept may also be applicable to LDL cholesterol measurement provided suitable antibodies specific to HDL and VLDL are available.
Animals↗
In utero bone marrow transplantation induces donor-specific tolerance by a combination of clonal deletion and clonal anergy.
BACKGROUND/PURPOSE: In utero bone marrow transplantation can induce donor-specific tolerance to postnatal solid organ transplantation, although the mechanisms remain poorly defined. In this study, we investigated the role of clonal deletion and clonal anergy in the maintenance of tolerance in a murine model of in utero bone marrow transplantation. METHODS: DBA/2 mice (MIs(a+)) were used as donors of adult bone marrow, and 14-day-gestation fetal Balb/c mice (MIs(a-)) were used as recipients. Tolerance was defined by donor-specific skin graft survival for more than 8 weeks. Clonal deletion was assessed by flow cytometry for Vbeta6 T cell receptor usage. A tolerant animal demonstrating partial deletion of CD4+/Vbeta6+ T cells and a nontolerant animal were selected for analysis of clonal anergy by a proliferation assay using plate-bound anti-Vbeta6 antibody for stimulation with or without exogenous interleukin-2 (IL2). RESULTS: Vbeta6+ splenocytes constituted 6.32% of CD4+ T cells in the tolerant animal compared with 9.19% in the nontolerant animal, demonstrating incomplete clonal deletion in the tolerant animal. Stimulation with plate-bound anti-Vbeta6 induced a good proliferative response in the nontolerant animal but a significantly attenuated response in the tolerant animal (P< .001), which was abrogated by the addition of IL2. CONCLUSIONS: In this murine model of in utero bone marrow transplantation, the tolerant state is characterized by partial clonal deletion of donor reactive T cells and clonal anergy of nondeleted donor reactive T cells. The anergic state can be abrogated by exogenous IL2, suggesting that the mechanism of anergy is a deficiency of IL2 production.
Animals↗
Persistent postnatal transgene expression in both muscle and liver after fetal injection of recombinant adenovirus.
BACKGROUND/PURPOSE: Immune responses to both vector and transgene antigens have limited the efficacy of postnatal gene therapy. We hypothesize that the fetal period may offer immunologic and developmental advantages for successful gene therapy. In this study we examined the efficacy, persistence, and immunologic effects of recombinant adenovirus after intramuscular delivery into fetal mice. METHODS: E1-deleted adenovirus (AdCMVlacZ) containing the beta-galactosidase marker gene was used for injection. Fetal Balb/c mice (14 to 15 days' gestation) were injected with AdCMVlacZ in 10-microL volume in either the shoulder or hindlimb musculature. Animals were killed at 18 to 20 days' gestation and up to 4 months postnatally for analysis of transgene expression and adenoviral genome persistence. RESULTS: Fetuses were injected with doses of AdCMVlacZ from 1 x 10(8) to 2 x 10(10) viral particles (n = 80). Optimal survival rate was 83% at 18 to 20 days' gestation and 55% at 4 weeks of age using a dose of 1 x 10(9) particles. Expression of beta-galactosidasae at 18 to 20 days localized to multiple muscle groups surrounding the site of injection, as well as bone marrow stroma, liver, lung, and dorsal root ganglia. Persistent muscle and liver transgene expression was observed for as long as 16 and 8 weeks, respectively, after injection. The pattern of liver expression was confined to discrete foci of hepatocytes, which appeared to increase in size in older animals. No histological evidence of muscle or liver inflammation was observed at any time after injection. No neutralizing antibodies were observed postnatally. CONCLUSIONS: Our results confirm that gene therapy in the fetus may be advantageous. Distribution of vector in the fetus at the site of injection is clearly broader than in the adult setting. Furthermore, the absence of immune response and persistence of transgene expression suggests that fetal exposure to foreign transgene and vector antigens may induce tolerance. Although we have not proven genomic integration, the histological appearance of transgene expression in the liver supports this conclusion. By understanding the mechanisms that underlie persistent transgene expression, fetal gene therapy may become a feasible strategy for the treatment of fatal genetic diseases.
Adenoviridae↗
The role of ultrasonography in fetal surgery and invasive fetal procedures.
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Congenital Abnormalities↗
Spectrum of opportunistic infections and malignancies in patients with human immunodeficiency virus infection in South Korea.
To determine the frequency and types of major opportunistic diseases in patients with HIV infection in South Korea, we reviewed the medical records of 173 HIV-infected patients. The patients were seen from 1985 to 1998 at a referral hospital for AIDS in South Korea. Most patients (85%) were male, and 107 (62%) were infected by heterosexual contacts. CD4+ lymphocyte counts at presentation were <200/microL in 27% of the patients. Tuberculosis was the most frequent opportunistic infection (25% of patients), followed by candidiasis (21%), herpes zoster (20%), Pneumocystis carinii pneumonia (10%), cytomegalovirus disease (9.8%). There were no cases of toxoplasmosis. Kaposi's sarcoma developed in 3 patients (1.7%), and non-Hodgkin's lymphoma, in 2 (1.2%). Eleven patients (6.4%) developed peripheral neuropathy, and 8 (4.6%) had HIV encephalopathy. Tuberculosis was the single most important HIV-related infection in South Korean patients.
AIDS-Related Opportunistic Infections↗
Expression and distribution of extracellular matrices during corneal wound healing after keratomileusis in rabbits.
We compared the corneal wound healing responses of keratomileusis and keratectomy in rabbits. A single pass of thin lamellar keratectomy was performed with a microkeratome in rabbits. The lenticule was repositioned with a hinge in one group and discarded in the other. With immunofluorescence techniques, we studied the appearance and distribution of fibronectin, fibrinogen and type III collagen at follow-up intervals from 1 h to 3 months. Fibronectin and fibrinogen began to deposit on the periphery of the denuded stroma 3 h after induced injury and diminished once reepithelialization had completed in both groups. In the corneas with attached lenticules, type III collagen was detected 7 days after surgery and lasted for at least 3 months. Type III collagen was detected only in the periphery of the interface and not in its center. These findings suggest that fibronectin and fibrinogen may play roles in epithelial healing after in situ keratomileusis in rabbits. Stromal healing of collagen seems to take place 7 days after keratomileusis and to last for several months. No deposits of new collagens in the center of the interface between lenticule and stromal bed may explain the optical clarity in the keratomileusis.
Animals↗
An aural myiasis case in a 54-year-old male farmer in Korea.
A 54-year-old male farmer residing in Chunchon, Korea, complaining of blood tinged discharge and tinnitus in the left ear for two days, was examined in August 16, 1996. Otoscopic examination revealed live maggots from the ear canal. The patient did not complain of any symptoms after removal of maggots. Five maggots recovered were identified as the third stage larvae of Lucilia sericata (Diptera: Calliphoridae). This is the first record of aural myiasis in Korea.
Animals↗
The effect of the haptic portion of intraocular lens on the development of posterior capsular opacification in rabbit.
Using a white rabbit model, the effect of the haptic portion of the intraocular lens (IOL) and intracapsular ring on the development of posterior capsular opacification (PCO) after extracapsular cataract extraction (ECCE) with phacoemulsification was studied. Implantation of both the intracapsular ring and IOL developed less PCO than implantation of the IOL alone. ECCE followed by implantation of the intracapsular ring alone also developed less PCO than ECCE alone. Through this experimental work in a rabbit model, it could be conceived that the haptic portion of IOL and the intracapsular ring can prevent the development of PCO.
Animals↗