501
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Kim G, Mehta M, Kucharczyk W, Blaser S. Spontaneous regression of a tectal mass in neurofibromatosis 1. AJNR Am J Neuroradiol 1998; 19:1137-9. [PMID: 9672027 PMCID: PMC8338634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
MR images showed an enhancing, enlarging mass in the tectum of the midbrain in a child with neurofibromatosis type 1. The mass was presumed to be a tectal glioma, which initially enlarged then regressed in size over a 3-year period and ceased to enhance. Although a tissue diagnosis was not available, we believe the temporal evolution of this lesion is strong presumptive evidence of a hamartoma. This case argues for the conservative management of patients with neurofibromatosis type 1 when possible.
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502
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Bergin A, Kim G, Price DL, Sisodia SS, Lee MK, Rabin BA. Identification and characterization of a mouse homologue of the spinal muscular atrophy-determining gene, survival motor neuron. Gene 1997; 204:47-53. [PMID: 9434164 DOI: 10.1016/s0378-1119(97)00510-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Spinal muscular atrophy (SMA), the second most common fatal, autosomal recessive disease of infants, manifests as generalized muscle weakness. The most severe form (Type I, Werdnig-Hoffmann disease) is associated with quadriplegia, respiratory muscle paralysis and death in infancy. Less severe forms are classified as Type II and Type III, based on age of onset and ultimate motor disability. Some spinal motor neurons show chromatolysis and the number of these cells is decreased. Recently, SMA has been mapped to chromosome 5q11.2-13.3 (Gilliam et al., 1990), a region that contains three candidate genes: Survival Motor Neuron (SMN) (Lefebvre et al., 1995); Neuronal Apoptosis Inhibitory Protein (NAIP) (Roy et al., 1995); and p44, a subunit of transcription factor II H (TFIIH) (Carter et al., 1995; Bürglen et al., 1997). Homozygous deletions or deleterious mutations in SMN are present in all SMA patients, and in some affected individuals, deletions have been identified in one or both of the other genes. These extensive deletions may be associated with a more severe phenotype. We have identified and characterized the mouse homologue of SMN, MoSMN, which is 82% identical to SMN at the amino-acid level. Unlike the duplicated human SMN, MoSMN is present in single copy. Like its human counterpart, MoSMN is ubiquitously expressed, but unlike SMN, MoSMN does not appear to be alternatively spliced. In-situ hybridization analysis of the mouse nervous system revealed that MoSMN mRNA is expressed in spinal cord and throughout the brain, with relatively higher levels of expression in the hippocampus and cerebellum.
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503
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Morris JR, Kim G, Barstis TLO, Mitra R, Jacobs DC. Dynamics of dissociative scattering: Hyperthermal energy collisions of state-selected OCS+ on Ag(111). J Chem Phys 1997. [DOI: 10.1063/1.474305] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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504
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Kim G, Daneman A, Alton DJ, Myers M, Sandler A, Superina R. The appearance of inverted Meckel diverticulum with intussusception on air enema. Pediatr Radiol 1997; 27:647-50. [PMID: 9252428 DOI: 10.1007/s002470050204] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This paper presents the appearances of inverted Meckel diverticulum with an irreducible intussusception on air enema in four children. The inverted Meckel diverticulum appeared as a bulbous (3) or triangular (1) filling defect in the air column projecting off the distal end of the soft tissue mass of the irreducible intussusceptum. The bulbous defect appears to be highly suggestive, and may be specific, for inverted Meckel diverticulum. Earlier recognition of the presence of the Meckel diverticulum as the lead point of the intussusception could have changed the management in two of the children.
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505
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Lee MK, Borchelt DR, Kim G, Thinakaran G, Slunt HH, Ratovitski T, Martin LJ, Kittur A, Gandy S, Levey AI, Jenkins N, Copeland N, Price DL, Sisodia SS. Hyperaccumulation of FAD-linked presenilin 1 variants in vivo. Nat Med 1997; 3:756-60. [PMID: 9212102 DOI: 10.1038/nm0797-756] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mutations in the presenilin 1 (PS1) and presenilin 2 (PS2) genes can cause Alzheimer's disease in affected members of the majority of early-onset familial Alzheimer's disease (FAD) pedigrees. PS1 encodes an ubiquitously expressed, eight transmembrane protein. PS1 is endoproteolytically processed to an amino-terminal derivative (approximately 27-28 kDa) and a carboxy-terminal derivative (approximately 17-18 kDa). These polypeptides accumulate to saturable levels in the brains of transgenic mice, independent of the expression of PS1 holoprotein. We now document that, in the brains of transgenic mice, the absolute amounts of accumulated N- and C-terminal derivatives generated from the FAD-linked PS1 variants in which Glu replaces Ala at codon 246 (A246E) or Leu replaces Met at codon 146 (M146L) accumulate to a significantly higher degree (approximately 40-50%) than the fragments derived from wild-type PS1. Moreover, the FAD-linked deltaE9 PS1 variant, a polypeptide that is not subject to endoproteolytic cleavage in vivo, also accumulates in greater amounts than the fragments generated from wild-type human PS1. Thus, the metabolism of PS1 variants linked to FAD is fundamentally different from that of wild-type PS1 in vivo.
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506
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Kim G, Yamabe H, Imadashirakata Y, Ueda S, Sakai M, Okuma M, Ishizaki K. p53 mutation and protein overexpression in the early stages of esophageal tumorigenesis utilizing endoscopically obtained biopsy specimens. Int J Oncol 1997; 10:683-8. [PMID: 21533431 DOI: 10.3892/ijo.10.4.683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
It is unclear whether p53 abnormality in the early esophageal tumorigenesis causes clonal expansion with tumor growth. In this study, we analyzed p53 abnormalities by PCR-SSCP and immunohistochemistry in 86 esophageal endoscopic biopsy specimens. Eleven of 27 specimens (39%) of mild dysplasias showed p53 mutations. Six moderate or mild dysplasias were followed by endoscopy (average 73 weeks) and continually exhibited the same p53 mutation, but none of them showed apparent tumor growth and subepithelial epithelial invasion. These results suggest that p53 mutations occur very early in the esophageal tumorigenesis and contribute to cell proliferation, but cannot be related with malignant phenotype directly.
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507
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Kim G. An examination of the couples' match. JAMA 1997; 277:765. [PMID: 9042852 DOI: 10.1001/jama.277.9.765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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508
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Bagarazzi ML, Boyer JD, Javadian MA, Chattergoon M, Dang K, Kim G, Shah J, Wang B, Weiner DB. Safety and immunogenicity of intramuscular and intravaginal delivery of HIV-1 DNA constructs to infant chimpanzees. J Med Primatol 1997; 26:27-33. [PMID: 9271186 DOI: 10.1111/j.1600-0684.1997.tb00316.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Any global strategy for controlling the human immunodeficiency virus (HIV) epidemic is likely to rely heavily on immunization of infants and children. Given the well-documented differences in children's responses to traditional vaccines, we initiated this study to extend our findings on DNA vaccination of adult chimpanzees to immunologically immature infant chimpanzees. Our findings were consistent with our previous work in adults as we observed that the DNA vaccines used here were both well tolerated and immunogenic within weeks of the initial vaccination.
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509
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Lee MK, Slunt HH, Martin LJ, Thinakaran G, Kim G, Gandy SE, Seeger M, Koo E, Price DL, Sisodia SS. Expression of presenilin 1 and 2 (PS1 and PS2) in human and murine tissues. J Neurosci 1996; 16:7513-25. [PMID: 8922407 PMCID: PMC6579112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Mutations in genes encoding related proteins, termed presenilin 1 (PS1) and presenilin 2 (PS2), are linked to the majority of cases with early-onset familial Alzheimer's disease (FAD). To clarify potential function(s) of presenilins and relationships of presenilin expression to pathogenesis of AD, we examined the expression of PS1 and PS2 mRNA and PS1 protein in human and mouse. Semi-quantitative PCR of reverse-transcribed RNA (RT-PCR) analysis revealed that PS1 and PS2 mRNA are expressed ubiquitously and at comparable levels in most human and mouse tissues, including adult brain. However, PS1 mRNA is expressed at significantly higher levels in developing brain. In situ hybridization studies of mouse embryos revealed widespread expression of PS1 mRNA with a neural expression pattern that, in part, overlaps that reported for mRNA encoding specific Notch homologs. In situ hybridization analysis in adult mouse brain revealed that PS1 and PS2 mRNAs are enriched in neurons of the hippocampal formation and entorhinal cortex. Although PS1 and PS2 mRNA are expressed most prominently in neurons, lower but significant levels of PS1 and PS2 transcripts are also detected in white matter glial cells. Moreover, cultured neurons and astrocytes express PS1 and PS2 mRNAs. Using PS1-specific antibodies in immunoblot analysis, we demonstrate that PS1 accumulates as approximately 28 kDa N-terminal and approximately 18 kDa C-terminal fragments in brain. Immunocytochemical studies of mouse brain reveal that PS1 protein accumulates in a variety of neuronal populations with enrichment in somatodendritic and neuropil compartments.
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510
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Borchelt DR, Thinakaran G, Eckman CB, Lee MK, Davenport F, Ratovitsky T, Prada CM, Kim G, Seekins S, Yager D, Slunt HH, Wang R, Seeger M, Levey AI, Gandy SE, Copeland NG, Jenkins NA, Price DL, Younkin SG, Sisodia SS. Familial Alzheimer's disease-linked presenilin 1 variants elevate Abeta1-42/1-40 ratio in vitro and in vivo. Neuron 1996; 17:1005-13. [PMID: 8938131 DOI: 10.1016/s0896-6273(00)80230-5] [Citation(s) in RCA: 1091] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Mutations in the presenilin 1 (PS1) and presenilin 2 genes cosegregate with the majority of early-onset familial Alzheimer's disease (FAD) pedigrees. We now document that the Abeta1-42(43)/Abeta1-40 ratio in the conditioned media of independent N2a cell lines expressing three FAD-linked PS1 variants is uniformly elevated relative to cells expressing similar levels of wild-type PS1. Similarly, the Abeta1-42(43)/Abeta1-40 ratio is elevated in the brains of young transgenic animals coexpressing a chimeric amyloid precursor protein (APP) and an FAD-linked PS1 variant compared with brains of transgenic mice expressing APP alone or transgenic mice coexpressing wild-type human PS1 and APP. These studies provide compelling support for the view that one mechanism by which these mutant PS1 cause AD is by increasing the extracellular concentration of Abeta peptides terminating at 42(43), species that foster Abeta deposition.
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511
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Thinakaran G, Borchelt DR, Lee MK, Slunt HH, Spitzer L, Kim G, Ratovitsky T, Davenport F, Nordstedt C, Seeger M, Hardy J, Levey AI, Gandy SE, Jenkins NA, Copeland NG, Price DL, Sisodia SS. Endoproteolysis of presenilin 1 and accumulation of processed derivatives in vivo. Neuron 1996; 17:181-90. [PMID: 8755489 DOI: 10.1016/s0896-6273(00)80291-3] [Citation(s) in RCA: 798] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The majority of early-onset cases of familial Alzheimer's disease (FAD) are linked to mutations in two related genes, PS1 and PS2, located on chromosome 14 and 1, respectively. Using two highly specific antibodies against nonoverlapping epitopes of the PS1-encoded polypeptide, termed presenilin 1 (PS1), we document that the preponderant PS1-related species that accumulate in cultured mammalian cells, and in the brains of rodents, primates, and humans are approximately 27-28 kDa N-terminal and approximately 16-17 kDa C-terminal derivatives. Notably, a FAD-linked PS1 variant that lacks exon 9 is not subject to endoproteolytic cleavage. In brains of transgenic mice expressing human PS1, approximately 17 kDa and approximately 27 kDa PS1 derivatives accumulate to saturable levels, and at approximately 1:1 stoichiometry, independent of transgene-derived mRNA. We conclude that PS1 is subject to endoproteolytic processing in vivo.
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512
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Lindquist S, Kim G. Heat-shock protein 104 expression is sufficient for thermotolerance in yeast. Proc Natl Acad Sci U S A 1996; 93:5301-6. [PMID: 8643570 PMCID: PMC39240 DOI: 10.1073/pnas.93.11.5301] [Citation(s) in RCA: 168] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
In all organisms, mild heat pretreatments induce tolerance to high temperatures. In the yeast Saccharomyces cerevisiae, such pretreatments strongly induce heat-shock protein (Hsp) 104, and hsp104 mutations greatly reduce high-temperature survival, indicating Hsp1O4 plays a critical role in induced thermotolerance. Surprisingly, however, a heat-shock transcription factor mutation (hsf1-m3) that blocks the induction of Hsps does not block induced thermotolerance. To resolve these apparent contradictions, we reexamined Hsp expression in hsf1-m3 cells. HsplO4 was expressed at a higher basal level in this strain than in other S. cerevisiae strains. Moreover, whereas the hsf1-m3 mutation completely blocked the induction of Hsp26 by heat, it did not block the induction of Hsp1O4. HSP104 could not be deleted in hsf1-m3 cells because the expression of heat-shock factor (and the viability of the strain) requires nonsense suppression mediated by the yeast prion [PSI+], which in turn depends upon Hsp1O4. To determine whether the level of Hsp1O4 expressed in hsf1-m3 cells is sufficient for thermotolerance, we used heterologous promoters to regulate Hsp1O4 expression in other strains. In the presence of other inducible factors (with a conditioning pretreatment), low levels of Hsp1O4 are sufficient to provide full thermotolerance. More remarkably, in the absence of other inducible factors (without a pretreatment), high levels of Hsp1O4 are sufficient. We conclude that Hsp1O4 plays a central role in ameliorating heat toxicity. Because Hsp1O4 is nontoxic and highly conserved, manipulating the expression of Hsp1OO proteins provides an excellent prospect for manipulating thermotolerance in other species.
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513
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Kim G, Yurkow EJ. Chromium induces a persistent activation of mitogen-activated protein kinases by a redox-sensitive mechanism in H4 rat hepatoma cells. Cancer Res 1996; 56:2045-51. [PMID: 8616849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Chromium is an important industrial metal, an environmental pollutant, and a human carcinogen. To investigate the mechanisms of chromium-induced carcinogenesis, activation of mitogen-activated protein (MAP) kinases ERK1 and ERK2 was examined in rat hepatoma cells following exposure to hexavalent chromium (Cr(VI)). Cr(VI) was found to activate both forms of MAP kinase in a dose- and time-dependent manner. In contrast to the protein kinase C (PKC) agonist, phorbol 12-myristate 13-acetate, which induced a transient activation of MAP kinases, Cr(VI) caused persistent activation of these enzymes. Furthermore, unlike phorbol 12-myristate 13-acetate, the ability of chromium to activate MAP kinases was found to be independent of PKC since chromium-induced MAP kinase activation occurred in PKC-depleted cells. Stimulation of ERK1 and ERK2 was associated with the ability of Cr(VI) to increase cellular peroxide levels as determined using the H2O2-sensitive fluorescent probe 2',7'-dichlorofluorescein diacetate and flow cytometry. Furthermore, the activation of these kinases by chromium was enhanced in cells treated with the glutathione-depleting agent, L-buthionine-[S,R]-sulfoximine, and attenuated in cells pretreated with an agent that elevates cellular levels of glutathione (i.e., N-acetyl-L-cysteine). The ability of chromium to modulate MAP kinase activity in this manner suggests a mechanism of chromium-induced carcinogenesis that involves the persistent stimulation of cellular regulatory pathways.
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514
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Griffith BP, Brett-Smith H, Kim G, Mellors JW, Chacko TM, Garner RB, Cheng YC, Alcabes P, Friedland G. Effect of stavudine on human immunodeficiency virus type 1 virus load as measured by quantitative mononuclear cell culture, plasma RNA, and immune complex-dissociated antigenemia. J Infect Dis 1996; 173:1252-5. [PMID: 8627080 DOI: 10.1093/infdis/173.5.1252] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The antiviral effect of stavudine (2', 3'-didehydro-3'-deoxythymidine) against human immunodeficiency virus (HIV) type 1 was measured in 15 HIV-infected patients at baseline and at weeks 4, 10, 22, 34, and 52 of therapy. Patients received 0.1, 0.5, 1.0, or 2.0 mg/kg/day of stavudine. At all time points examined during the 52 weeks of therapy, the median virus titers in peripheral blood mononuclear cells were decreased 1-2 logs, and median immune complex-dissociated antigen levels were reduced 37%-67% compared with baseline values. Plasma RNA content measured by polymerase chain reaction was reduced approximately 0.5 log from baseline median values at both time points examined (weeks 10 and 52). These data demonstrate that stavudine has a substantial and durable antiviral effect.
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515
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Hussain N, Kim G, Church T, Carey W. A simplified technique for gamma-spectrometric analysis of 210Pb in sediment samples. Appl Radiat Isot 1996. [DOI: 10.1016/0969-8043(95)00319-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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516
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Kim G. Determination of titanium solubility in alpha-aluminum during high energy milling. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/0956-716x(95)00521-v] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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517
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Borchelt D, Lee M, Thinakaran G, Wong P, Slunt H, Ratovitski T, Kim G, Jenkins N, Copeland N, Price D. 95 Synthesis and metabolism of presenilin 1 with mutations linked to familial Alzheimer's disease in transgenic mice. Neurobiol Aging 1996. [DOI: 10.1016/s0197-4580(96)80097-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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518
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Kim G, Davis D. Hydrodynamic instabilities in flat-plate-type fuel assemblies. NUCLEAR ENGINEERING AND DESIGN 1995. [DOI: 10.1016/0029-5493(95)01023-b] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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519
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Kim G, Suh HH, Lee EH. Green's-function study of the electron tunneling in a double-barrier heterostructure. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:2632-2639. [PMID: 9981330 DOI: 10.1103/physrevb.52.2632] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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520
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Yurkow EJ, Kim G. Effects of chromium on basal and insulin-induced tyrosine phosphorylation in H4 hepatoma cells: comparison with phorbol-12-myristate-13-acetate and sodium orthovanadate. Mol Pharmacol 1995; 47:686-95. [PMID: 7536887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Chromium, in its various forms, is recognized both as a human carcinogen and as a nutrient essential in glucose homeostasis. Although the genotoxicity of this element is associated with its carcinogenic properties, the manner in which chromium mediates its epigenetic effects on cells, including its ability to potentiate insulin action, is not known. In the current studies, Western blotting with antiphosphotyrosine antibodies was used to study the effects of chromium on protein tyrosine phosphorylation in intact H4 rat hepatoma cells. Treatment of cells with hexavalent chromium [Cr(VI)] was found to induce the tyrosine phosphorylation of three prominent sets of proteins, having median molecular masses of 210, 125, and 87 kDa. Cr(VI) pretreatment also inhibited the insulin-induced tyrosine phosphorylation of the major substrate of the insulin receptor kinase, insulin receptor substrate-1, and its subsequent association with the 85-kDa regulatory subunit (p85) of phosphatidylinositol 3'-kinase. Furthermore, Cr(VI) was found to alter the pattern of other p85-binding (insulin-induced) phosphoproteins that were distributed throughout the soluble and particulate fractions of cells. Virtually all of the alterations in basal and insulin-induced phosphorylations associated with Cr(VI) treatment were also observed in cells treated with the protein kinase C (PKC) agonist phorbol-12-myristate-13-acetate. However, the effects of Cr(VI) were determined to be independent of PKC activity, because they were sustained in PKC-depleted cells. The pattern of phosphoproteins induced by Cr(VI) also had similarities to the pattern generated in response to the phosphatase inhibitor sodium orthovanadate. However, several specific differences, including the ability of vanadate to increase insulin receptor beta subunit autophosphorylation [i.e., an effect not observed with Cr(VI)], indicated that these agents modulate phosphorylation by distinct mechanisms. The ability of Cr(VI) to alter the phosphorylation state of key regulatory proteins in a manner similar to that of other biologically active agents suggests a mechanism by which this element can modulate the growth and metabolism of cells.
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521
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Kimura W, Kim G, Romea R, Steinhauer L, Pogorelsky I, Kusche K, Fernow R, Wang X, Liu Y. Laser Acceleration of Relativistic Electrons Using the Inverse Cherenkov Effect. PHYSICAL REVIEW LETTERS 1995; 74:546-549. [PMID: 10058785 DOI: 10.1103/physrevlett.74.546] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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522
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Kim G, Choi YW, Park PW, Chu HY, Lee EH, Arnold GB. Green's-function approach to the electronic structure of double-barrier quantum-well heterostructures. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:7582-7586. [PMID: 9974740 DOI: 10.1103/physrevb.50.7582] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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523
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Nishizaki Y, Guth PH, Kim G, Wayland H, Kaunitz JD. Pentagastrin enhances gastric mucosal defenses in vivo: luminal acid-dependent and independent effects. THE AMERICAN JOURNAL OF PHYSIOLOGY 1994; 267:G94-104. [PMID: 8048536 DOI: 10.1152/ajpgi.1994.267.1.g94] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Stimulation of acid secretion is associated with enhanced resistance of the gastric mucosa to damage by luminal acid. We studied the mechanism by which gastric mucosal defenses are modulated in a system in which mucus gel thickness, intracellular pH (pHi), gastric mucosal blood flow, and acid secretion can be measured simultaneously in vivo, using a recently developed microfluorometric technique. Intravenous infusion of pentagastrin in a dose associated with maximal acid secretion increased mucus gel thickness, pHi, and mucosal blood flow during superfusion with a neutral solution. Subsequent superfusion with an acidic buffer (pH 1.7) further increased blood flow to nearly three times basal. During superfusion with luminal acid, pHi fell more slowly and recovered toward baseline more quickly in pentagastrin-infused rats than in controls. Pretreatment with the H2-receptor antagonist cimetidine abolished the increased blood flow associated with pentagastrin, impairing pHi homeostasis, although cimetidine increased mucus gel thickness in the absence of pentagastrin. We conclude that gastric defense mechanisms at the preendothelial and postepithelial levels are enhanced during acid secretion as part of a histamine-dependent homeostatic mechanism that balances gastric protective mechanisms with acid secretion. The net result of these enhanced defenses is the preservation of gastric surface cell pHi despite the presence of a large proton gradient between lumen and blood.
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524
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Kim DK, Kim G, Gam J, Cho YB, Kim HT, Tai JH, Kim KH, Hong WS, Park JG. Synthesis and antitumor activity of a series of [2-substituted-4,5-bis(aminomethyl)-1,3-dioxolane]platinum(II) complexes. J Med Chem 1994; 37:1471-85. [PMID: 8182706 DOI: 10.1021/jm00036a013] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The synthesis, physical properties, antitumor activity, structure-activity relationships, and nephrotoxicity of a series of [2-substituted-4,5-bis(aminomethyl)-1,3-dioxolane]platinum(II) complexes are described. The 42 platinum(II) complexes having a seven-membered ring structure in this series have been prepared and characterized by 1H NMR, 13C NMR, IR, FAB-MS, and elemental analysis. All members of the series were designed to have a 1,3-dioxolane ring moiety in their carrier ligands to increase water solubility. The solubility of platinum complexes was related to the nature of leaving ligands and 2-substituents in the 4,5-bis(aminomethyl)-1,3-dioxolane carrier ligands. In general, compounds having two different R1 and R2 substituents in the 4,5-bis(aminomethyl)-1,3-dioxolane moiety were more water-soluble than those having the same substituents. Most members of this series showed the excellent antitumor activity against murine L1210 leukemia cells transplanted in mice and were superior to cisplatin and carboplatin. The (4R,5R)-stereoisomer 1a-h exhibited the higher antitumor activity than the corresponding (4S,5S)-stereoisomer 2a-h in the (1,1-cyclobutanedicarboxylato)platinum(II) complexes. The (glycolato)-platinum(II) complexes were highly cytotoxic toward four human stomach cancer cell lines, SNU-1, SNU-5, SNU-16, and NCI-N87, and among them, complexes 3d-g were even more cytotoxic than cisplatin. The (malonato)platinum(II) complex 1m and the (glycolato)platinum(II) complexes 3d-g were selected for further studies based on the greater in vivo and in vitro antitumor activity and desirable physical properties. The complexes 3e-g were almost equally cytotoxic to cisplatin toward human stomach cancer cell lines, KATO-III and MKN-45, and a human non-small cell lung cancer cell line, PC14. In contrast with cisplatin and carboplatin, five complexes selected significantly increased in life span in mice transplanted with cisplatin-resistant L1210 cells. Nephrotoxicity studies in ICR mice indicated that serum BUN and creatinine levels were not elevated when five complexes were given at a dose equal to 1.5 times the optimal dose determined in the in vivo L1210 screening system.
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525
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Hahm K, Kim G, Turck CW, Smale ST. Isolation of a murine gene encoding a nucleic acid-binding protein with homology to hnRNP K. Nucleic Acids Res 1993; 21:3894. [PMID: 8367306 PMCID: PMC309919 DOI: 10.1093/nar/21.16.3894] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
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