Biomedical subjects

J Kim

Publications and source records attributed to J Kim.

At least 505 records · Page 28Linked to original sources

PubMed2000

Epitope location on tissue factor determines the anticoagulant potency of monoclonal anti-tissue factor antibodies.

Tissue factor (TF), the cellular cofactor for the serine protease factor VIIa (F.VIIa), triggers blood coagulation and is involved in the pathogenesis of various thrombosis-related disorders. Therefore, agents which specifically target tissue factor, such as monoclonal antibodies, may provide promising new antithrombotic therapy. We mapped the epitopes of several anti-TF antibodies using a panel of soluble TF mutants. They bound to three distinct TF regions. The epitope of the 7G11 antibody included Phe50 and overlapped with a TF-F.VIIa light chain contact area. The common epitope of the antibodies 6B4 and HTF1 included residues Tyr94 and Phe76 both of which make critical contacts to the catalytic domain of F.VIIa. The antibodies D3 and 5G6 had a common epitope outside the TF-F.VIIa contact region. It included residues Lys 165, Lys 166, Asn199, Arg200 and Lys201 and thus overlapped with the substrate interaction region of tissue factor. The antibodies 5G6 and D3 were potent anticoagulants when infused to flowing human blood in an ex-vivo thrombosis model. Plasma fibrinopeptide A levels and fibrin deposition were completely inhibited. In contrast, 6B4 was a weak inhibitor in this ex-vivo thrombosis model, and HTF1 displayed no inhibition at all. These disparate activities were also reflected in TF-dependent F.X activation assays performed with human plasma. The potency differences could neither be explained by the determined binding affinities nor by the on-rates of antibodies. Therefore, the results suggest that antibody binding epitope and hence the particular mechanism of inhibition, is the main determinative factor of anticoagulant potency of anti-TF antibodies.

Antibodies, Monoclonal↗

PubMed2000

Fiber size and myosin phenotypes of selected rhesus lower limb muscles after a 14-day spaceflight.

Muscle biopsies were taken from the rhesus (Macaca mulatta) soleus (Sol, a slow ankle extensor), medial gastrocnemius (MG, a fast ankle extensor), tibialis anterior (TA, a fast ankle flexor), and vastus lateralis (VL, a fast knee extensor) muscles in vivarium controls (n=5) before and after either a 14-day spaceflight (Bion 11, n=2) or a 14-day ground-based flight simulation (n=3). Myosin heavy chain (MHC) composition (gel electrophoresis), fiber type distribution (immunohistochemistry), and fiber size were determined. Although there were no significant changes, each muscle showed trends towards adaptation.

Animals↗

PubMed2000

Engineering of DNA vaccines using molecular adjuvant plasmids.

These studies support the view that additional goals of enhancing DNA vaccine technology will probably be at several levels. The ability to deliver antigens more efficiently to professional APCs is likely to have important implications for our studies of basic principles of immunology. Furthermore, there are simple practical approaches to vaccine enhancement that can be tested with the present group of DNA vaccines. These studies should include the use of cytokine molecular adjuvants as well as possible co-stimulatory molecules. It is expected that the delivery of these "adjuvanted" DNA vaccines will require additional safety evaluation; however, it is clear that studies can be easily designed to address the important safety issues associated with these novel vaccine adjuvants. Overall, the results indicate that further more precise quantitative studies and combination studies examining these additional promising adjuvant candidates are warranted.

AIDS Vaccines↗

PubMed2000

Reforming the Medicaid disproportionate share hospital program.

Since 1991, three Federal laws have sought to reform the Medicaid disproportionate share hospital (DSH) program, which is designed to help safety net hospitals. This article provides findings from a 40-State survey about Medicaid DSH and supplemental payment programs in 1997. Results indicate that the overall size of the DSH program did not grow from 1993 to 1997, but the composition of DSH revenues and expenditures changed substantially: A much higher share of the DSH funds were being paid to local hospitals and relatively less was being retained by the States. The study also revealed that large differences in States' use of DSH still persist.

Data Collection↗

PubMed1999

Modification of EWS/WT1 functional properties by phosphorylation.

In many human cancers, tumor-specific chromosomal rearrangements are known to create chimeric products with the ability to transform cells. The EWS/WT1 protein is such a fusion product, resulting from a t(11;22) chromosomal translocation in desmoplastic small round cell tumors, where 265 aa from the EWS amino terminus are fused to the DNA binding domain of the WT1 tumor suppressor gene. Herein, we find that EWS/WT1 is phosphorylated in vivo on serine and tyrosine residues and that this affects DNA binding and homodimerization. We also show that EWS/WT1 can interact with, and is a substrate for, modification on tyrosine residues by c-Abl. Tyrosine phosphorylation of EWS/WT1 by c-Abl negatively regulates its DNA binding properties. These results indicate that the biological activity of EWS/WT1 is closely linked to its phosphorylation status.

Animals↗

PubMed1999

Strategies for supercritical fluid extraction of hyoscyamine and scopolamine salts using basified modifiers.

The supercritical fluid extraction behaviors of hyoscyamine and scopolamine were investigated and found to be highly dependent upon the chemical nature of the compounds. Free bases of hyoscyamine and scopolamine were freely soluble in supercritical CO2 with increasing temperature and pressure; however, the salts of these alkaloids were not soluble under any experimental conditions. It was found that alkaline modifiers such as methanol basified with diethylamine could enhance the solubilities and extraction yields of these alkaloids from plant matrices as compared to other modifiers.

Atropine↗

PubMed1999

Restricted immunoglobulin variable region (Ig V) gene expression accompanies secondary rearrangements of light chain Ig V genes in mouse plasmacytomas.

The many binding studies of monoclonal immunoglobulin (Ig) produced by plasmacytomas have found no universally common binding properties, but instead, groups of plasmacytomas with specific antigen-binding activities to haptens such as phosphorylcholine, dextrans, fructofuranans, or dinitrophenyl. Subsequently, it was found that plasmacytomas with similar binding chain specificities not only expressed the same idiotype, but rearranged the same light (V(L)) and heavy (V(H)) variable region genes to express a characteristic monoclonal antibody. In this study, we have examined by enzyme-linked immunosorbent assay five antibodies secreted by silicone-induced mouse plasmacytomas using a broader panel of antigens including actin, myosin, tubulin, single-stranded DNA, and double-stranded DNA. We have determined the Ig heavy and light chain V gene usage in these same plasmacytomas at the DNA and RNA level. Our studies reveal: (a) antibodies secreted by plasmacytomas bind to different antigens in a manner similar to that observed for natural autoantibodies; (b) the expressed Ig heavy genes are restricted in V gene usage to the V(H)-J558 family; and (c) secondary rearrangements occur at the light chain level with at least three plasmacytomas expressing both kappa and lambda light chain genes. These results suggest that plasmacytomas use a restricted population of B cells that may still be undergoing rearrangement, thereby bypassing the allelic exclusion normally associated with expression of antibody genes.

Amino Acid Sequence↗

PubMed1999

Evidence for autoregulation of cystathionine gamma-synthase mRNA stability in Arabidopsis.

Control of messenger RNA (mRNA) stability serves as an important mechanism for regulating gene expression. Analysis of Arabidopsis mutants that overaccumulate soluble methionine (Met) revealed that the gene for cystathionine gamma-synthase (CGS), the key enzyme in Met biosynthesis, is regulated at the level of mRNA stability. Transfection experiments with wild-type and mutant forms of the CGS gene suggest that an amino acid sequence encoded by the first exon of CGS acts in cis to destabilize its own mRNA in a process that is activated by Met or one of its metabolites.

Amino Acid Sequence↗

PubMed1999

Molecular genetics of chromosome translocations involving EWS and related family members.

Many types of sarcomas are characterized by specific chromosomal translocations that appear to result in the production of novel, tumor-specific chimeric transcription factors. Many of these show striking similarities: the emerging picture is that the amino-terminal domain of the fusion product is donated by the Ewing's sarcoma gene (EWS) or a related member from the same gene family, whereas the carboxy-terminal domain often consists of a DNA-binding domain derived from one of a number of transcription factors. Given the observation that the different translocation partners of the EWS protooncogene are associated with distinct types of sarcomas, the functional consequence of fusing EWS (or a related family member) to a different DNA-binding domain can only be understood in the context of functional studies that define the specificity of action of the different fusion products. An understanding of the molecular structure and function of these translocations provides new methods for diagnosis and novel targets for therapeutics.

DNA-Binding Proteins↗

PubMed1999

Octamer-based genome scanning distinguishes a unique subpopulation of Escherichia coli O157:H7 strains in cattle.

Multilocus-genotyping methods have shown that Escherichia coli O157:H7 is a geographically disseminated clone. However, high-resolution methods such as pulse-field gel electrophoresis demonstrate significant genomic diversity among different isolates. To assess the genetic relationship of human and bovine isolates of E. coli O157:H7 in detail, we have developed an octamer-based genome-scanning methodology, which compares the distance between over-represented, strand-biased octamers that occur in the genome. Comparison of octamer-based genome-scanning products derived from >1 megabase of the genome demonstrated the existence of two distinct lineages of E. coli O157:H7 that are disseminated within the United States. Human and bovine isolates are nonrandomly distributed among the lineages, suggesting that one of these lineages may be less virulent for humans or may not be efficiently transmitted to humans from bovine sources. Restriction fragment length polymorphism analysis with lambdoid phage genomes indicates that phage-mediated events are associated with divergence of the lineages, thereby providing one explanation for the degree of diversity that is observed among E. coli O157:H7 by other molecular-fingerprinting methods.

Animals↗

PubMed1999

Induction of mouse Ca(2+)-sensitive chloride channel 2 gene during involution of mammary gland.

To understand molecular mechanisms that regulate mammary gland involution, we identified involution-induced cDNA clones by suppression subtractive hybridization methods. Nucleotide sequencing of a clone revealed that it was 97% identical to Ca(2+)-sensitive chloride channel 1 (mCLCA1) gene that has been identified in lung tissue. We concluded that our clone was derived from different gene with mCLCA1 and named it mCLCA2. We confirmed that expression of mCLCA2 gene was predominant in mammary gland while mCLCA1 mRNA was mainly detected in lung tissues by RT-PCR. Northern analysis showed that the mCLCA2 gene was induced at involution phase compared to pregnant and lactating phases of mammary gland. Under serum starvation, HC11 mammary epithelial cells showed DNA fragmentation and induction of mCLCA2 expression.

Amino Acid Sequence↗

PubMed1999

SHC-alpha5beta1 integrin interactions regulate breast cancer cell adhesion and motility.

The oncogenic SHC proteins are signaling substrates for most receptor and cytoplasmic tyrosine kinases (TKs) and have been implicated in cellular growth, transformation, and differentiation. In tumor cells overexpressing TKs, the levels of tyrosine phosphorylated SHC are chronically elevated. The significance of amplified SHC signaling in breast tumorigenesis and metastasis remains unknown. Here we demonstrate that seven- to ninefold overexpression of SHC significantly altered interactions of cells with fibronectin (FN). Specifically, in human breast cancer cells overexpressing SHC (MCF-7/SHC) the association of SHC with alpha5beta1 integrin (FN receptor) was increased, spreading on FN was accelerated, and basal growth on FN was reduced. These effects coincided with an early decline of adhesion-dependent MAP kinase activity. Basal motility of MCF-7/SHC cells on FN was inhibited relative to that in several cell lines with normal SHC levels. However, when EGF or IGF-I was used as the chemoattractant, the locomotion of MCF-7/SHC cells was greatly (approx fivefold) stimulated, while it was only minimally altered in the control cells. These data suggest that SHC is a mediator of the dynamic regulation of cell adhesion and motility on FN in breast cancer cells.

Adaptor Proteins, Signal Transducing↗

PubMed1999

Expression of BDNF and TrkB mRNAs in the crista neurosensory epithelium and vestibular ganglia following ototoxic damage.

Following ototoxic lesion with the aminoglycoside gentamicin, the vestibular neurosensory epithelia undergo degeneration and then limited spontaneous regeneration. The spatio-temporal expression of brain-derived neurotrophic factor (BDNF) and of its high affinity receptor (trkB) mRNA was investigated in the vestibular end organs and ganglia of chinchillas following gentamicin ototoxicity. In the vestibular ganglia of untreated chinchillas, the level of expression of BDNF mRNA is low. At 1 and 2 weeks after intraotic treatment with gentamicin, BDNF mRNA levels in the vestibular ganglia were elevated significantly compared to untreated chinchillas and chinchillas 4 weeks after treatment. At 4 weeks after gentamicin treatment, BDNF mRNA levels were at intact levels of expression. In the crista ampullaris, high levels of BDNF transcripts were found in the untreated chinchillas. At 1 and 2 weeks after treatment, when only supporting cells are present in the crista, BDNF mRNA was undetectable. Four weeks after aminoglycoside treatment BDNF mRNA was present in the epithelium but at lower levels than in the intact epithelium. In contrast to its ligand, high levels of trkB mRNA hybridization were present in the vestibular ganglia of untreated chinchillas and trkB mRNA levels did not change following gentamicin treatment. In the vestibular epithelia, trkB mRNA was not detected either in the intact epithelium or after gentamicin ototoxicity. These data suggest that BDNF may be involved in the maintenance of the vestibular ganglia and contribute to neurite outgrowth to new and repaired hair cells following ototoxic damage.

Animals↗

PubMed1999

Inhibitory effects of chlorophyllin on 7,12-dimethylbenz[a]anthracene-induced bacterial mutagenesis and mouse skin carcinogenesis.

Chlorophyllin (CHL), a water-soluble derivative of chlorophyll, has been used for the treatment of several abnormal human conditions without apparent toxicity. Recent studies have revealed that CHL has the excellent chemopreventive potential. In the present investigation, we have found the inhibitory activities of CHL against 7,12-dimethylbenz[a]anthracene (DMBA)-induced mutagenesis in Salmonella typhimurium TA100 and also on DMBA-initiated and 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-promoted mouse skin tumor formation. The incidence and the multiplicity of skin tumors were not significantly decreased in mice by a single topical application of CHL prior to the DMBA treatment, but there was a marked suppression of papillomagenesis in mice treated with CHL during the promotional stage. Furthermore, the formation of DMBA-induced papillomagenesis was reduced in all mice that had received CHL for 6 weeks following treatment with TPA for 6, 18 and 24 weeks. These results indicate that CHL can inhibit both tumor promotion and the progression of papillomagenesis in the two-stage mouse skin carcinogenesis induced by DMBA and TPA.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1999

HIV-1 DNA vaccines and chemokines.

DNA vaccines have a demonstrated ability to induce humoral and cellular immune responses in animal models and humans. The technology, although it dates back to the 1950's, has had an insurgence of interest within the past few years following concurrent research papers. The basic technology is being applied broadly to viral, bacterial and parasitic infections. It has also been demonstrated that genes delivered via plasmid expression vectors result in expression of functional proteins in the inoculated host. Further, injection of plasmids encoding cytokine, chemokine or co-stimulatory molecules, also referred to as immunomodulatory plasmids can lead to the further expansion of this technology to include directed immunology. We have been developing DNA technology specifically with a focus as a vaccine against HIV-1 infection. We report that such vaccines can stimulate immune responses in a variety of relevant animal systems including humoral and cellular responses as well as the production of beta-chemokines. We describe that the beta-chemokines can both modulate the immune response induced by DNA vaccines and be modulated by the DNA vaccines in the murine and chimpanzee models as well as in humans.

AIDS Vaccines↗

PubMed1999

Overexpression of phospholipase C-gamma1 suppresses UVC-induced apoptosis through inhibition of c-fos accumulation and c-Jun N-terminal kinase activation in PC12 cells.

Ultraviolet-C (UVC) irradiation induces DNA damage and UVC-irradiated cells undergo cell growth arrest to repair the damaged DNA or the induction of apoptosis to prevent the risk of neoplastic transformation. Phospholipase C-gamma1 (PLC-gamma1) is a mediator of growth factor induced-signal cascade, catalyzing the hydrolysis of phosphatidyl 4,5-bisphosphate to generate second messengers, diacylglycerol and inositol 1,4,5-trisphosphate (IP(3)). PLC-gamma1 is activated by phosphorylation of tyrosine residues upon occupation of cell surface receptors by growth factors and plays an important role in controlling cellular proliferation and differentiation. In this study, we found that PLC-gamma1 was tyrosine phosphorylated within 2.5 min after UVC irradiation. To investigate the role of UVC-induced tyrosine phosphorylation of PLC-gamma1, we compared the effect of UVC between PLC-gamma1 overexpressing cells and empty vector transfected cells. Overexpression of PLC-gamma1 inhibited UVC-induced sub-diploid peak and DNA fragmentation. Northern blot analysis revealed that UVC-induced c-fos mRNA accumulation was inhibited in PLC-gamma1 overexpressing cells, while c-jun expression was not affected. In addition, UVC-induced activation of c-Jun N-terminal kinase (JNK) was significantly suppressed in PLC-gamma1 overexpressing cells. These results suggest that PLC-gamma1 may associate with the protective function against the UVC-induced cell death progression via the inhibition of accumulation of c-fos mRNA and the inhibition of JNK kinase activity.

Animals↗

PubMed1999

Cloning and characterization of a nuclear S6 kinase, S6 kinase-related kinase (SRK); a novel nuclear target of Akt.

Akt is stimulated by several growth factors, and mediates their cell survival signals. Recent studies have shown that Akt may play an intermediate role between phosphatidylinositol 3-kinase (PI3K) and p70 S6 kinase (p70S6K). Here we show that a novel nuclear p70S6K-related kinase (SRK) exists and that its in vivo function is also augmented by over-expression of Akt. Conceptual translation of the SRK cDNA revealed that the catalytic domain of SRK was highly homologous to that of p70S6K, and that the treatment of wortmannin or rapamycin strongly inhibited the phosphorylation and the activation of SRK, as in p70S6K. However, the N- and C-terminal domains of SRK were quite different from those of p70S6K. In immunolocalization analyses, we demonstrated a constitutive nuclear localization of SRK and the presence of a nuclear localization signal in its C-terminus. In vitro S6 phosphotransferase activities of SRK were stimulated with a slower kinetics by a variety of agonists to p70S6K. Interestingly, over-expression of the proto-oncogene Akt resulted in EGF-independent activation of SRK, while over-expression of kinase-dead Akt actually had an inhibitory effect. This relationship between Akt and SRK suggests that SRK may be a novel target of Akt and perhaps an important downstream component in the nuclear function of Akt.

Catalytic Domain↗

PubMed1999

Anatomical characteristics and three-dimensional model of the dog dorsal lateral geniculate body.

The morphological and laminar characteristics of the dorsal lateral geniculate nucleus (LGN) and medial interlaminar nucleus (MIN) of the domestic dog (Canis familiaris) were studied by three-dimensional computer reconstruction of labeled retinal afferents following intraocular HRP injections. As previously reported, the dog LGN consisted of layers A, A1, C, C1, C2, and C3. Layers A, C, and C2 receive contralateral-eye inputs, and layers A1 and C1 ipsilateral inputs. The dog MIN was found to have four orderly interdigitating layers; layers 1, 2, 3, and 4, medial to lateral. MIN layers 1 and 3 received contralateral inputs, and layers 2 and 4 ipsilateral inputs. Layer 1 had the largest soma of all LGN/MIN layers. LGN layer A was partially separated into medial and lateral subdivisions by a cleft free of somata. The overall three-dimensional shape of the lateral geniculate body was like the letter C, with the convex part of the C directed posteriorly. The relative volume of the MIN was smaller than in the cat; the canine MIN comprised 8.3% of the combined volume of layers A, A1 and the MIN, while that of the cat comprised 14.2% as estimated from Sanderson's map. The volume of all contralateral-eye layers, combining both LGN and MIN, was 31.2 mm(3) (78%), and that for ipsilateral layers was 8.6 mm(3) (22%). The ratio of ipsilateral to contralateral laminar volumes is much lower in the dog than in the cat.

Animals↗