Biomedical subjects

Yong-Joo Kim

Publications and source records attributed to Yong-Joo Kim.

6 recordsLinked to original sources

PubMed2006

Monoclonal antibody-based competitive enzyme-linked immunosorbent assay for detecting and quantifying West Nile virus-neutralizing antibodies in horse sera.

A rapid immunoassay for detecting and quantifying West Nile virus (WNV)-neutralizing antibodies in sera was developed as an alternative to the plaque reduction neutralization test (PRNT), the gold standard test for WNV. The assay is a competitive, enzyme-linked immunosorbent assay using neutralizing monoclonal antibody 5E8 (NT-ELISA). A cutoff percent inhibition (PI) value of 35% (mean PI plus 3 standard deviations), with a specificity of 99%, was established based on analysis of 246 serum samples from horses free of WNV. The NT-ELISA detected neutralizing antibodies in all sera collected 7 or 14 days postinoculation from mice (n = 11) infected with lineage I (strain NY385-99) or II (strain B956) WNV. When sera from WNV-vaccinated horses (n = 212) were tested by NT-ELISA and PRNT, the NT-ELISA gave a positive result for 96.1% (173/180) of the PRNT-positive sera and 3.1% (1/32) of the PRNT-negative sera. Discrepancies between the two tests were observed mainly with sera with low PRNT(90) titers (expressed as the reciprocal of the highest dilution yielding > or = 90% reduction in the number of plaques) for WNV or low PIs by NT-ELISA. The overall agreement (k value) between the two tests was 0.86. A good correlation (r(2) = 0.77) was also observed between the tests for endpoint titration of sera (n = 116). In conclusion, the newly developed NT-ELISA may be a good alternative serologic assay for detecting WNV that can be used for large-scale testing of WNV-neutralizing antibodies in multiple species.

Animals↗

PubMed2006

The DE loop of the domain III of the envelope protein appears to be associated with West Nile virus neutralization.

The envelope (E) protein of WNV plays an important role in the virus neutralization. Using a mAb 5E8, a neutralizing epitope on the domain III of the E of the New York strain of WN virus was characterized. Results from neutralization-escape mutants and site-directed mutagenesis revealed that the 5E8 epitope is a highly conformation dependent epitope consisting of at least residues E330, E332 and E367 on the domain III. Besides known critical neutralizing epitopes E330 and E332, our results indicate that residue E367, a component of DE loop on the domain III, appeared to be associated with neutralization but little with neuroinvasion of the virus, as reported previously (Beasley et al., 2002).

Immunodominant Epitopes↗

PubMed2005

Bis(isothiocyanato)bis(phosphine) complexes of group 10 metals: reactivity toward organic isocyanides.

Treatment of Ni(NCS)2(PMe2Ph)2 with organic isocyanides CN-R gave five-coordinate isocyanide Ni(II) complexes, Ni(CN-R)(NCS)2(PMe2Ph)2 (R = C6H3-2,6-Me2 (1), t-Bu (2)). Interestingly, the corresponding reaction of Ni(NCS)2(P(n-Pr)3)2 with 2 equiv. of CN-t-Bu gave an unusual compound, which exists as an ion pair of the trigonal bipyramidal cation [Ni(P(n-Pr)3)2(CN-t-Bu)3]2+ (3) and the dinuclear NCS-bridged anion [Ni(1,3-micro-NCS)(NCS)3]2(2-) (4). In contrast, Pd(NCS)2(P(n-Pr)3)2 underwent substitution with 2 equiv. of CN-t-Bu to give the four-coordinate mono(isocyanide) Pd(II) complex Pd(NCS)(SCN)(CN-t-Bu)(P(n-Pr)3) (5) via phosphine dissociation. Reactions of M(NCS)2L2 (M = Pd, Pt; L = PMe3, PEt3, PMePh2, P(n-Pr)3) with two equiv. of CN-R (R = t-Bu, i-Pr, C6H3-2,6-Me2) gave the corresponding bis(isocyanide) complexes [M(CN-R)2(PR3)2](SCN)2 (7-13), except for Pd(NCS)2(PEt3)2 that reacted with CN-R' (R' = i-Pr, C6H3-2,6-Me2) and produced the mono(isocyanide) Pd(II) complexes [Pd(CN-R')(SCN)(PEt3)2](SCN) (14 and 15). Finally, treatment of M(NCS)2(PMe3)2 (M = Ni, Pd, Pt) with sterically bulky isocyanide CN-C6H3-2,6-i-Pr2 gave various products, (16-18) depending on the identity of the metal.

Journal Article↗

PubMed2005

Gene knockdown by large circular antisense for high-throughput functional genomics.

Single-stranded genomic DNA of recombinant M13 phages was tested as an antisense molecule and examined for its usefulness in high-throughput functional genomics. cDNA fragments of various genes (TNF-alpha, c-myc, c-myb, cdk2 and cdk4) were independently cloned into phagemid vectors. Using the life cycle of M13 bacteriophages, large circular (LC)-molecules, antisense to their respective genes, were prepared from the culture supernatant of bacterial transformants. LC-antisense molecules exhibited enhanced stability, target specificity and no need for target-site searches. High-throughput functional genomics was then attempted with an LC-antisense library, which was generated by using a phagemid vector that incorporated a unidirectional subtracted cDNA library derived from liver cancer tissue. We identified 56 genes involved in the growth of these cells. These results indicate that an antisense sequence as a part of single-stranded LC-genomic DNA of recombinant M13 phages exhibits effective antisense activity, and may have potential for high-throughput functional genomics.

Animals↗

PubMed2004

Vapochromism and its structural basis in a luminescent Pt(II) terpyridine-nicotinamide complex.

A novel Pt(II) terpyridine complex that has a nicotinamide moiety linked to the terpyridyl ligand has been synthesized in good yield and studied structurally and spectroscopically. The complex, [Pt(Nttpy)Cl](PF(6))(2) where Nttpy = 4'-(p-nicotinamide-N-methylphenyl)-2,2':6',2' '-terpyridine, is observed to be brightly luminescent in the solid state at room temperature and at 77 K. The complex exhibits reversible vapochromic behavior and crystallographic change in the presence of several volatile organic solvents. Upon exposure to methanol vapors, the complex changes color from red to orange, and a shift to higher energy is observed in the emission maximum with an increase in excited-state lifetime and emission intensity. The crystal and molecular structures of the orange and red forms, determined by single-crystal X-ray diffraction on the same single crystal, were found to be equivalent in the molecular sense and only modestly different in terms of packing. In both forms, the cationic Pt(II) complexes possess distorted square planar geometries. Analysis of the orange form's crystal packing reveals the presence of solvent molecules in lattice voids, Pt...Pt separations averaging 3.75 A and a zigzag arrangement between nearest neighbor Pt atoms, whereas the red form is devoid of solvent within the crystal lattice and contains complexes stacked with a nearly linear arrangement of Pt(II) ions having an average distance of 3.33 A. On the basis of the crystallographic data, it is evident that sorption of methanol vapor induces a change in intermolecular contacts and Pt...Pt interactions in going from red to orange. Disruption of the d(8)-d(8) metallophilic interactions consequently alters the emitting state from (3)[(d)sigma*-pi*(terpyridine)] that is formally a metal-metal-to-ligand charge transfer (MMLCT) state in the red form to one in which the HOMO corresponds to a more localized Pt(d) orbital in the red form ((3)MLCT).

Crystallography, X-Ray↗

PubMed2004

Cyclometallated Pd(II) azido complexes containing 6-phenyl-2,2'-bipyridyl or 2-phenylpyridyl derivatives: synthesis and reactivity toward organic isocyanides and isothiocyanates.

Cyclometallated palladium(II) azido complexes containing C,N,N- or C,N-donor ligands, [Pd(N(3))L](HL = 6-phenyl-2,2'-bipyridine or 2-phenylpyridyl derivatives), showed different reactivities toward organic isocyanides and isothiocyanates. In particular, aryl isocyanides (CN-Ar) underwent insertion into the orthometallated Pd-C bond on the phenyl moiety of the supporting ligand (L) in [Pd(N(3))L] or [Pd(N(3))(PR(3))L] to selectively give carbodiimido [[Pd(N=C=N-Ar)L]], imidoyl [[Pd(N(3))(-C=N-Ar)(PR(3))L]], or imidoyl carbodiimido complexes [[Pd(N=C=N-Ar)(-C=N-Ar)L] or [Pd(N=C=N-Ar)(-C=N-Ar)(PR(3))L]], depending on reaction conditions. Interestingly, reactions of [Pd(N(3))(PR(3))L] with organic isothiocyanates gave unusual dinuclear complexes [(micro-SCN(4)-R)PdL](2), exhibiting the concurrent S- and N-coordinating thio-tetrazole bridge.

Journal Article↗